WO2021131898A1 - Method for manufacturing water absorbing resin particles, and method for manufacturing polymer particles - Google Patents

Method for manufacturing water absorbing resin particles, and method for manufacturing polymer particles Download PDF

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Publication number
WO2021131898A1
WO2021131898A1 PCT/JP2020/046732 JP2020046732W WO2021131898A1 WO 2021131898 A1 WO2021131898 A1 WO 2021131898A1 JP 2020046732 W JP2020046732 W JP 2020046732W WO 2021131898 A1 WO2021131898 A1 WO 2021131898A1
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particle group
polymer particle
mass
sieve
surface cross
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PCT/JP2020/046732
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French (fr)
Japanese (ja)
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志保 岡澤
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住友精化株式会社
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Publication of WO2021131898A1 publication Critical patent/WO2021131898A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating

Definitions

  • the present invention relates to a method for producing water-absorbent resin particles and a method for producing polymer particles.
  • an absorber containing water-absorbent resin particles has been used as an absorbent article for absorbing a liquid (for example, urine) containing water as a main component.
  • the water-absorbent resin particles in the absorber are required to have excellent liquid diffusivity in addition to having a high water absorption amount.
  • the liquid diffusibility generally tends to decrease as the proportion of fine powder in the water-absorbent resin particles increases. That is, the fine powder in the water-absorbent resin particles tends to block the path for the liquid to diffuse when swollen, and tends to cause so-called "gel blocking".
  • the fine powder is removed as described above, the number of water-absorbent resin particles that become the product decreases. Therefore, in order not to deteriorate the productivity, it is required to utilize the fine powder in the product. Therefore, it is required to obtain excellent water absorption characteristics while utilizing fine powder, and as the water absorption characteristics, for example, in consideration of the usage mode in which the water absorption resin particles are pressurized, excellent water absorption characteristics under pressure are obtained. Is required.
  • the present inventor focused on utilizing fine powder that passes through a sieve having a mesh size of 212 ⁇ m or less, and obtained water-absorbent resin particles having excellent water absorption characteristics under pressure by using such fine powder. I was inspired. On the other hand, the present inventor obtains one obtained by subjecting each of a plurality of polymer particle groups classified by a sieve having a mesh size of 212 ⁇ m or less to surface cross-linking and then subjecting fine powder to surface cross-linking. It has been found that by mixing the polymer particle group with another polymer particle group, it is possible to obtain water-absorbent resin particles having excellent water-absorbing properties under pressure while utilizing fine powder.
  • One aspect of the present invention is the polymer particle group A2 obtained by subjecting the polymer particle group A1 remaining on the sieve S1 to surface cross-linking when the polymer particle group is classified by the sieve S1 having a mesh size of 212 ⁇ m or less.
  • a method for producing a water-absorbent resin particle which comprises a step of obtaining the sex resin particle.
  • polymer particles having excellent water absorption characteristics under pressure can be obtained by subjecting fine powder passing through a sieve having a mesh size of 212 ⁇ m or less to surface cross-linking under specific conditions. It was.
  • Another aspect of the present invention is that when the polymer particle group is classified by a sieve having a mesh size of 212 ⁇ m or less, the polymer particle group B1 that has passed through the sieve and the surface cross-linking agent are mixed at 0 to 20 ° C.
  • the present invention provides a method for producing polymer particles, which comprises a step of subjecting the polymer particle group B1 to surface crosslinks.
  • Another aspect of the present invention is the polymer particle group B1 that has passed through the sieve when the polymer particle group is classified by a sieve having a mesh size of 212 ⁇ m or less using a surface cross-linking agent solution containing alcohol and water.
  • a method for producing polymer particles which comprises a step of subjecting a surface crosslink and has a volume ratio of the alcohol to water of 0.25 to 2.00.
  • the materials exemplified in the present specification may be used alone or in combination of two or more.
  • the content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified.
  • “Saline” refers to a 0.9% by mass sodium chloride aqueous solution.
  • Room temperature means 25 ° C.
  • a particle group which is an aggregate of particles may be described as "particle”.
  • CRC is an abbreviation for Centrifuge Retention Capacity (centrifuge holding capacity).
  • the CRC can be measured by the method described in Examples described later with reference to the EDANA method (NWSP 241.0.R2 (15), page.769-778).
  • the absorption ratio (AAP) under pressurization of 4.83 kPa (0.7 psi) can be measured by the method described in the column of [Example] described later.
  • the CRC and the absorption ratio under pressurization of 4.83 kPa the measured value at room temperature can be used.
  • the mass of the polymer particle group (for example, the expression such as "100 parts by mass of the polymer particle group" below) is the solid content of the polymer particle group. Means.
  • the method for producing the water-absorbent resin particles according to the present embodiment is when the polymer particle group is classified by a sieve S1 having a mesh size of 212 ⁇ m or less.
  • the polymer particle group A2 obtained by surface cross-linking the polymer particle group A1 remaining on the sieve S1 and the polymer particle group A2 having a mesh size of 212 ⁇ m or less were used to classify the polymer particle group, the polymer particle group passed through the sieve S2.
  • the present invention comprises a mixing step of obtaining water-absorbent resin particles (water-absorbent resin particle group) by mixing the polymer particle group B1 obtained by subjecting the polymer particle group B1 with a surface-crosslinked polymer particle group B2.
  • suitable surface cross-linking can be performed on each of the polymer particle group A1 and the polymer particle group B1.
  • suitable surface cross-linking By mixing the polymer particle group A2 and the polymer particle group B2 obtained by performing suitable surface cross-linking, for example, a uniform surface cross-linking state can be achieved in the entire water-absorbent resin particles.
  • the factors capable of obtaining excellent water absorption characteristics are not limited to the above-mentioned contents.
  • the suitable surface cross-linking conditions for the polymer particle group A1 and the polymer particle group B1 are the same, the same conditions may be used for the surface cross-linking after classification.
  • the mixing amount of the polymer particle group B2 is preferably less than 50 parts by mass, more preferably 45 parts by mass or less, further preferably 40 parts by mass or less, and 35 parts by mass or less from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is particularly preferable, 33 parts by mass or less is extremely preferable, 30 parts by mass or less is very preferable, 25 parts by mass or less is even more preferable, 20 parts by mass or less is further preferable, 15 parts by mass or less is particularly preferable, and 12 parts by mass or less. Is extremely preferable.
  • the mixing amount of the polymer particle group B2 is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, from the viewpoint of enhancing the utilization efficiency of the fine powder. 9 parts by mass or more is extremely preferable, 10 parts by mass or more is very preferable, and 11 parts by mass or more is even more preferable. From these viewpoints, the mixing amount of the polymer particle group B2 is preferably 1 part by mass or more and less than 50 parts by mass, more preferably 5 to 30 parts by mass, and further preferably 10 to 20 parts by mass.
  • the CRC of the polymer particle group A2 is preferably in the following range.
  • the CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 27 g / g or more, particularly preferably 28 g / g or more, extremely preferably 29 g / g or more, and very preferably 30 g / g or more.
  • 31 g / g or more is even more preferable
  • 33 g / g or more is further preferable
  • 35 g / g or more is particularly preferable
  • 36 g / g or more is extremely preferable.
  • the CRC is preferably 60 g / g or less, more preferably 55 g / g or less, further preferably 50 g / g or less, particularly preferably 45 g / g or less, extremely preferably 40 g / g or less, and very preferably 38 g / g or less. .. From these viewpoints, the CRC is preferably 20 to 60 g / g, more preferably 20 to 50 g / g, and even more preferably 25 to 40 g / g.
  • the absorption ratio (AAP) of the polymer particle group A2 under pressurization of 4.83 kPa is preferably 6.0 g / g or more, more preferably 6.5 g / g or more, further preferably 7.0 g / g or more, and 7. 5 g / g or more is particularly preferable, 8.0 g / g or more is extremely preferable, 8.5 g / g or more is very preferable, 9.0 g / g or more is further preferable, 10.0 g / g or more is further preferable, and 10.0 g / g or more is further preferable.
  • the upper limit of the absorption ratio (AAP) of the polymer particle group A2 under pressure of 4.83 kPa is, for example, 40.0 g / g or less, 35.0 g / g or less, 30.0 g / g or less, 25.0 g / g or less. Or, it may be 20.0 g / g or less.
  • the CRC of the polymer particle group B2 is preferably in the following range.
  • the CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 30 g / g or more, particularly preferably 31 g / g or more, extremely preferably 32 g / g or more, and very preferably 33 g / g or more. , 34 g / g or more is even more preferable.
  • the CRC is preferably 60 g / g or less, more preferably 55 g / g or less, further preferably 50 g / g or less, particularly preferably 45 g / g or less, extremely preferably 40 g / g or less, and very preferably 35 g / g or less. .. From these viewpoints, the CRC is preferably 20 to 60 g / g, more preferably 20 to 50 g / g, and even more preferably 30 to 40 g / g.
  • the absorption ratio (AAP) of the polymer particle group B2 under pressure of 4.83 kPa is preferably 8.0 g / g or more, more preferably 9.0 g / g or more, further preferably 10.0 g / g or more, and 12. 0 g / g or more is particularly preferable, 15.0 g / g or more is extremely preferable, 18.0 g / g or more is very preferable, and 19.0 g / g or more is even more preferable.
  • the upper limit of the absorption ratio (AAP) of the polymer particle group B2 under pressure of 4.83 kPa is, for example, 40.0 g / g or less, 35.0 g / g or less, 30.0 g / g or less, 25.0 g / g or less. Or, it may be 20.0 g / g or less.
  • At least two or more polymer particle groups among the classified groups may be surface-crosslinked and mixed with each other. In this case, all of the classifieds may be mixed with each other, and some of the classified polymer particle groups may not be mixed.
  • the temperature at which the polymer particle group A2 and the polymer particle group B2 are mixed in the mixing step may be 5 ° C. or higher and lower than 100 ° C., 5 to 90 ° C., or 5 to 80 ° C.
  • the polymer particle group A2 is a polymer particle group obtained by subjecting the polymer particle group A1 remaining on the sieve S1 to surface cross-linking when the polymer particle group is classified by a sieve S1 having a mesh size of 212 ⁇ m or less. ..
  • the polymer particle group B2 is a polymer particle group obtained by subjecting the polymer particle group B1 that has passed through the sieve S2 to surface cross-linking when the polymer particle group is classified by a sieve S2 having a mesh size of 212 ⁇ m or less.
  • the polymer particle group to be classified using the sieve S1 or the sieve S2 is a polymer particle that has passed through the sieve when the polymer particle group is classified with a sieve having an opening of 850 ⁇ m or more from the viewpoint of removing coarse particles. It may be a group.
  • the polymer particle group to be classified using the sieve S1 or the sieve S2 has a weight remaining on the sieve when the polymer particle group is classified with a sieve having an opening of 45 ⁇ m or less from the viewpoint of removing extremely small fine powder. It may be a coalesced particle group.
  • the polymer particle group A1 and the polymer particle group B1 may be obtained by classifying the same polymer particle group from each other, or may be obtained by classifying different polymer particle groups from each other.
  • the sieve S1 and the sieve S2 are the same sieve (the same product).
  • the sieve S1 and the sieve S2 may be different sieves or the same sieves.
  • the polymer particle group C is classified by a sieve S1 (the sieve S1 and the sieve S2 are the same sieves) before the mixing step to classify the polymer.
  • the classification step I for obtaining the particle group A1 and the polymer particle group B1 may be provided.
  • the method for producing the water-absorbent resin particles according to the second embodiment includes a classification step IIa for obtaining the polymer particle group A1 by classifying the polymer particle group D1 with a sieve S1 before the mixing step, and a polymer particle group.
  • a classification step IIb for obtaining the polymer particle group B1 by classifying the polymer particle group D2 different from D1 with a sieve S2 may be provided.
  • the meshes of the sieve S1 and the sieve S2 may be the same or different from each other.
  • the sieves S1 and S2, which are different sieves from each other may be classified (the sieve S2 may be a sieve different from the sieve S1).
  • one of the classification step IIa and the classification step IIb was performed using the sieves S1 and S2 which are the same sieves (same thing) as each other.
  • the other of the classification step IIa and the classification step IIb may be performed later (that is, the classification may be repeated with the same sieve).
  • the polymer particle group D1 and the polymer particle group D2 in the method for producing water-absorbent resin particles according to the second embodiment are different polymer particle groups from each other.
  • the polymer particle group D1 and the polymer particle group D2 may be a polymer particle group produced under the same conditions.
  • the polymer particle group of one of the polymer particle group D1 and the polymer particle group D2 is a polymer particle group obtained by subjecting the other of the polymer particle group D1 and the polymer particle group D2 to various treatments. Good.
  • the polymer particle group of one of the polymer particle group D1 and the polymer particle group D2 is before or after various treatments of the other polymer particle group of the polymer particle group D1 and the polymer particle group D2. It may be a polymer particle group different from the later polymer particle group.
  • the polymer particle group to be classified can be classified into a plurality of polymer particle groups, and the sieve S1 or the sieve S2 may be used to classify the polymer particle group into two polymer particle groups. It may be classified into three or more polymer particle groups by a plurality of sieves containing.
  • the polymer particle group C may be classified into the polymer particle group A1 and the polymer particle group B1 by a sieve S1.
  • the polymer particle group D1 may be classified into two by a sieve S1, and the polymer particle group D1 may be classified into two by a plurality of sieves including the sieve S1. It may be classified into three or more.
  • the polymer particle group D2 may be classified into two by a sieve S2, and the polymer particle group D2 may be classified into two by a plurality of sieves including the sieve S2. It may be classified into three or more.
  • a sieve having a mesh size of 212 ⁇ m or less As the sieve having a mesh size of 212 ⁇ m or less (sieve S1 and sieve S2), a sieve having a mesh size of 212 ⁇ m or less specified in JIS Z8801-1 may be used.
  • the mesh size of the sieve may be 180 ⁇ m or less.
  • the mesh size of the sieve may be 45 ⁇ m or more, 75 ⁇ m or more, 90 ⁇ m or more, 106 ⁇ m or more, 125 ⁇ m or more, 150 ⁇ m or more, or 180 ⁇ m or more.
  • the CRC of the polymer particle group to be classified using the sieve S1 or the sieve S2 is preferably in the following range.
  • the CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 30 g / g or more, particularly preferably 35 g / g or more, from the viewpoint of easily increasing the absorption amount when used in an absorbent article. 39 g / g or more is extremely preferable.
  • the CRC is preferably 80 g / g or less, preferably 70 g / g or less, further preferably 60 g / g or less, particularly preferably 55 g / g or less, and particularly preferably 50 g / g or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is extremely preferable, 45 g / g or less is very preferable, and 40 g / g or less is even more preferable. From these viewpoints, the CRC is preferably 20 to 80 g / g, more preferably 25 to 60 g / g, and even more preferably 30 to 50 g / g.
  • the medium particle size of the polymer particle group to be classified using the sieve S1 or the sieve S2 is preferably in the following range.
  • the medium particle size is from the viewpoint that it is easy to obtain excellent water absorption characteristics under pressure in the water-absorbent resin particles, and from the viewpoint that it is easy to maintain good absorption performance when used in an absorbent article by avoiding gel blocking. , 200 ⁇ m or more is preferable, 230 ⁇ m or more is more preferable, and 250 ⁇ m or more is further preferable.
  • the medium particle size is preferably 600 ⁇ m or less, more preferably 550 ⁇ m or less, further preferably 500 ⁇ m or less, particularly preferably 450 ⁇ m or less, and extremely preferably 400 ⁇ m or less, from the viewpoint of easily keeping the tactile sensation soft when used in an absorbent article. .. From these viewpoints, the medium particle size is preferably 200 to 600 ⁇ m, more preferably 230 to 500 ⁇ m, and even more preferably 250 to 400 ⁇ m.
  • the medium particle size is preferably 260 ⁇ m or more, more preferably 280 ⁇ m or more, further preferably 300 ⁇ m or more, particularly preferably 330 ⁇ m or more, and particularly preferably 350 ⁇ m or more, from the viewpoint of easily obtaining more excellent water absorption characteristics under pressure in the water-absorbent resin particles. Is extremely preferable.
  • the medium particle size is preferably 350 ⁇ m or less, more preferably 320 ⁇ m or less, further preferably 300 ⁇ m or less, particularly preferably 280 ⁇ m or less, and extremely preferably 260 ⁇ m or less, from the viewpoint of easily obtaining a more excellent CRC in the water-absorbent resin particles.
  • the medium particle size can be measured by the method described in the [Example] column described later.
  • the medium particle size is a mass-based particle size, and a measured value at room temperature can be used.
  • the method for producing the water-absorbent resin particles according to the present embodiment includes a surface cross-linking step I in which the polymer particle group A1 is surface-crosslinked to obtain the polymer particle group A2 before the mixing step and after the classification step.
  • a surface cross-linking step II in which the polymer particle group B1 is surface-crosslinked to obtain the polymer particle group B2 may be provided.
  • the conditions for surface cross-linking in the surface cross-linking step I and the surface cross-linking step II may be the same as each other or may be different from each other.
  • the amount of the surface cross-linking agent used in the surface cross-linking step II is the surface in the surface cross-linking step I from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. It may be larger than the amount of the cross-linking agent used.
  • the surface cross-linking conditions in the surface cross-linking step II are compared with the surface cross-linking conditions in the surface cross-linking step I from the viewpoint of easily obtaining excellent water absorption characteristics under pressure, and the surface of the particles in the polymer particle group with respect to the inside It is preferable that the absorption rate of the cross-linking agent is slow.
  • the polymer particle group B1 which is a fine powder tends to have a higher absorption rate of the surface cross-linking agent than the polymer particle group A1, but in the polymer particle group B1, the absorption rate of the surface cross-linking agent to the inside of the particles is lowered.
  • the mixing temperature of the surface cross-linking agent in the surface cross-linking step II may be lower than the mixing temperature of the surface cross-linking agent in the surface cross-linking step I from the viewpoint of easily reducing the absorption rate of the surface cross-linking agent into the inside of the particles (mixing). Details of the temperature will be described later).
  • the amount of alcohol used in the surface cross-linking step II is such that the amount of alcohol that is difficult to be absorbed inside the particles increases, so that the absorption rate of the surface cross-linking agent into the inside of the particles tends to decrease. (As the amount used, for example, "volume ratio of alcohol to water" or "amount of alcohol used in the surface cross-linking agent solution” described later can be used).
  • the polymer particle group can be surface-crosslinked using a surface cross-linking agent for performing surface cross-linking.
  • a surface cross-linking agent for example, a compound containing two or more functional groups (reactive functional groups, for example, hydroxyl groups) having reactivity with a functional group derived from an ethylenically unsaturated monomer can be used.
  • the surface cross-linking agent include polyols such as 1,4-butanediol, diethylene glycol, triethylene glycol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; (poly) ethylene glycol diglycidyl ether.
  • Haloepoxy compounds such as; compounds having two or more reactive functional groups such as isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; 3-methyl-3-oxetanemethanol, 3-ethyl-3-oxetanemethanol , 3-butyl-3-oxetanemethanol, 3-methyl-3-oxetaneethanol, 3-ethyl-3-oxetaneethanol, 3-butyl-3-oxetaneethanol and other oxetane compounds; Oxazoline compounds; ethylene carbonate, propylene carbonate, 4,5-dimethyl-1,3-diox
  • the surface cross-linking agent may be used alone or in combination of two or more.
  • the surface cross-linking agent preferably contains a carbonate compound, more preferably contains an alkylene carbonate, and further preferably contains an ethylene carbonate, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • the polymer particle group can be surface-crosslinked using the following amount of the surface cross-linking agent for 100 parts by mass of the polymer particle group.
  • the amount of the surface cross-linking agent used is preferably in the following range with respect to 100 parts by mass of the polymer particle group.
  • the amount of the surface cross-linking agent used is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, still more preferably 0.05 parts by mass or more, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • 0.1 parts by mass or more is particularly preferable, 0.3 parts by mass or more is extremely preferable, 0.5 parts by mass or more is very preferable, 0.8 parts by mass or more is even more preferable, and 1.0 parts by mass or more is further preferable.
  • 1.2 parts by mass or more is particularly preferable, and 1.4 parts by mass or more is extremely preferable.
  • the amount of the surface cross-linking agent used is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 5 parts by mass or less, and particularly preferably 4 parts by mass or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • the amount of the surface cross-linking agent used is preferably 0.005 to 10 parts by mass, more preferably 0.01 to 10 parts by mass, further preferably 0.01 to 5 parts by mass, and 0.01 to 3 parts. Parts by mass are particularly preferable, parts by mass of 0.1 to 3 are extremely preferable, and parts by mass of 0.5 to 3 are very preferable.
  • the amount of the surface cross-linking agent used is preferably 1 to 10 parts by mass.
  • the amount of the surface cross-linking agent used may be 1.4 parts by mass or less, 1.2 parts by mass or less, 1 part by mass or less, or 0.9 parts by mass or less.
  • the surface cross-linking step it is possible to carry out surface cross-linking on 100 parts by mass of the polymer particle group B1 using the surface cross-linking agent solution (liquid containing the surface cross-linking agent) containing each of the above-mentioned amounts of the surface cross-linking agent.
  • 100 parts by mass of the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing 1 part by mass or more (for example, 1 to 10 parts by mass) of the surface cross-linking agent.
  • the polymer particle group can be surface-crosslinked by using the following amount of a carbonate compound (for example, alkylene carbonate) with respect to 100 parts by mass of the polymer particle group.
  • a carbonate compound for example, alkylene carbonate
  • the amount of the carbonate compound used is preferably in the following range with respect to 100 parts by mass of the polymer particle group.
  • the amount of the carbonate compound used is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, further preferably 0.1 part by mass or more, and 0, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • .3 parts by mass or more is particularly preferable, 0.5 parts by mass or more is extremely preferable, 0.6 parts by mass or more is very preferable, 0.7 parts by mass or more is further preferable, and 0.8 parts by mass or more is further preferable. , 0.9 parts by mass or more is particularly preferable.
  • the amount of the carbonate compound used is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 5 parts by mass or less, particularly preferably 4 parts by mass or less, and 3 parts by mass from the viewpoint of easily obtaining an appropriate CRC.
  • the following is extremely preferable, 2 parts by mass or less is very preferable, and 1 part by mass or less is even more preferable.
  • the amount of the carbonate compound used is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, further preferably 0.01 to 3 parts by mass, and 0.1 to 3 parts by mass. Parts are particularly preferable, and 0.5 to 3 parts by mass are extremely preferable.
  • the amount of the carbonate compound used is preferably 0.5 to 10 parts by mass.
  • the amount of the carbonate compound used may be 0.9 parts by mass or less, 0.7 parts by mass or less, or 0.5 parts by mass or less.
  • 100 parts by mass of the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing each of the above-mentioned amounts of the carbonate compound, for example, 0.5 parts by mass.
  • a surface cross-linking agent solution containing each of the above-mentioned amounts of the carbonate compound for example, 0.5 parts by mass.
  • 100 parts by mass of the polymer particle group B1 can be surface-crosslinked.
  • the polymer particle group and the surface cross-linking agent may be mixed at the following mixing temperature to perform surface cross-linking on the polymer particle group.
  • the mixing temperature of the polymer particle group and the surface cross-linking agent in the surface cross-linking step is preferably in the following range.
  • the mixing temperature is preferably 0 ° C. or higher, more preferably 1 ° C. or higher, further preferably 3 ° C. or higher, particularly preferably 5 ° C. or higher, and exceeding 5 ° C. or higher from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is extremely preferable, 10 ° C.
  • the mixing temperature is preferably 50 ° C. or lower, more preferably 45 ° C. or lower, further preferably 40 ° C. or lower, particularly preferably 35 ° C. or lower, and extremely preferably 30 ° C. or lower, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. , Less than 30 ° C. is very preferable, 25 ° C. or lower is even more preferable, less than 25 ° C. is further preferable, 20 ° C. or lower is particularly preferable, less than 20 ° C. is extremely preferable, 18 ° C. or lower is very preferable, and 15 ° C.
  • the mixing temperature is preferably 0 to 50 ° C., more preferably 5 to 30 ° C., and even more preferably 10 to 25 ° C.
  • the mixing temperature is also preferably 0 to 20 ° C.
  • the mixing temperature may exceed 15 ° C. or higher, may be 20 ° C. or higher, may exceed 20 ° C. or higher, and may be 22 ° C. or higher.
  • the polymer particle group B1 and the surface cross-linking agent can be mixed at the above-mentioned mixing temperatures to perform surface cross-linking on the polymer particle group B1.
  • the polymer particle group B1 and the surface can be cross-linked.
  • the cross-linking agent can be mixed at 20 ° C. or lower (for example, 0 to 20 ° C.) to perform surface cross-linking on the polymer particle group B1.
  • the surface cross-linking step may be carried out in the presence of water, and the presence of water in the range of 1 to 200 parts by mass with respect to 100 parts by mass of the monomer (for example, ethylenically unsaturated monomer) in the polymer particle group. You may go below. By adjusting the amount of water in the surface cross-linking step, the cross-linking in the vicinity of the particle surface can be adjusted.
  • the polymer particle group can be surface-crosslinked using a surface cross-linking agent solution containing at least one selected from the group consisting of a water-soluble organic solvent and water.
  • a water-soluble organic solvent include alcohol and the like.
  • alcohols lower alcohols such as methanol, ethanol, propanol and isopropanol; ketones such as acetone; ethers such as dioxane; amides such as N, N-dimethylformamide; sulfoxides such as dimethyl sulfoxide; ethylene glycol, Examples thereof include polyhydric alcohols such as propylene glycol.
  • the alcohol at least one selected from the group consisting of a compound having two or more (for example, two) hydroxyl groups and a compound having one hydroxyl group may be used.
  • the alcohol preferably contains at least one selected from the group consisting of propylene glycol and isopropanol, and more preferably isopropanol, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • the water-soluble organic solvent may be a compound corresponding to the above-mentioned surface cross-linking agent.
  • the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing isopropanol.
  • the surface cross-linking step it is possible to carry out surface cross-linking on the polymer particle group using a surface cross-linking agent solution containing alcohol, and the polymer particle group using the surface cross-linking agent solution containing the following amount of alcohol.
  • a surface cross-linking agent solution containing alcohol can contain at least one selected from the group consisting of alcohols that are surface cross-linking agents and alcohols that are not surface cross-linking agents.
  • the amount of alcohol used in the surface cross-linking agent solution is preferably in the following range based on the total mass of the surface cross-linking agent solution or the total amount of the surface cross-linking agent, alcohol and water that do not correspond to alcohol.
  • the amount of alcohol used is preferably 10% by mass or more, more preferably 12% by mass or more, further preferably 15% by mass or more, and particularly preferably 17% by mass or more, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. 18% by mass or more is extremely preferable, 20% by mass or more is very preferable, 22.5% by mass or more is further preferable, 25% by mass or more is further preferable, 27.5% by mass or more is particularly preferable, and 30% by mass or more. Is extremely preferable.
  • the amount of alcohol used is preferably 80% by mass or less, more preferably 75% by mass or less, further preferably 70% by mass or less, and particularly preferably 65% by mass or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. 60% by mass or less is extremely preferable, 55% by mass or less is very preferable, and 52% by mass or less is even more preferable. From these viewpoints, the amount of alcohol used is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, further preferably 20 to 60% by mass, and particularly preferably 30 to 55% by mass. The amount of alcohol used is also preferably 20 to 80% by mass.
  • the amount of alcohol used may be 31% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, 50% by mass or more, or 51% by mass or more.
  • the amount of alcohol used may be 51% by mass or less, 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 31% by mass or less.
  • the surface cross-linking step it is possible to carry out surface cross-linking on the polymer particle group B1 by using the above-mentioned surface cross-linking agent solution containing each amount of alcohol used, for example, 20% by mass or more of alcohol (for example, 20 to 20 to 20).
  • the polymer particle group B1 can be surface-crosslinked using a surface-crosslinking agent solution containing 80% by mass).
  • the volume ratio of alcohol to water is preferably in the following range.
  • the volume ratio is preferably 0.10 or more, more preferably 0.20 or more, further preferably 0.25 or more, particularly preferably 0.30 or more, and 0. 35 or more is extremely preferable, 0.40 or more is very preferable, and 0.45 or more is even more preferable.
  • the volume ratio is preferably 2.00 or less, more preferably 1.80 or less, further preferably 1.50 or less, particularly preferably 1.40 or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. 30 or less is extremely preferable, and 1.20 or less is very preferable.
  • the volume ratio is preferably 0.10 to 2.00, more preferably 0.25 to 1.50, and even more preferably 0.45 to 1.20.
  • the volume ratio is also preferably 0.25 to 2.00.
  • the volume ratio may be 0.50 or more, 0.70 or more, 0.90 or more, 1.00 or more, 1.10 or more, or 1.20 or more.
  • the volume ratio may be less than 1.20, 1.10 or less, 1.00 or less, 0.90 or less, 0.70 or less, 0.50 or less, or 0.30 or less.
  • the amount of alcohol used includes the amount of surface cross-linking agent used.
  • the volume ratio may be a volume ratio at 20 ° C. and can be calculated based on the density of alcohol and water at 20 ° C.
  • the density of propylene glycol is 1.04 g / cm 3
  • the density of isopropanol is 0.79 g / cm 3
  • the surface cross-linking step may be an embodiment in which the polymer particle group B1 is subjected to surface cross-linking using a surface cross-linking agent solution containing alcohol and water, and the volume ratio of alcohol to water is each of the above-mentioned volume ratios, for example.
  • the volume ratio of alcohol to water may be 0.25 or more (for example, 0.25 to 2.00).
  • the amount of alcohol used is preferably in the following range with respect to 100 parts by mass of the polymer particle group.
  • the amount of alcohol used is preferably 0.1 part by mass or more, more preferably 0.15 part by mass or more, further preferably 0.25 part by mass or more, and 0. 5 parts by mass or more is particularly preferable, 0.6 parts by mass or more is extremely preferable, 0.75 parts by mass or more is very preferable, 1 part by mass or more is further preferable, and 1.25 parts by mass or more is further preferable. 5 parts by mass or more is particularly preferable, 1.75 parts by mass or more is extremely preferable, 2 parts by mass or more is very preferable, 2.25 parts by mass or more is further preferable, and 2.5 parts by mass or more is further preferable.
  • the amount of alcohol used is preferably 5 parts by mass or less, more preferably 4.5 parts by mass or less, further preferably 4 parts by mass or less, and 3.5 parts by mass or less from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is particularly preferable, 3 parts by mass or less is extremely preferable, and 2.6 parts by mass or less is very preferable. From these viewpoints, the amount of alcohol used is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 4 parts by mass, and even more preferably 1 to 3 parts by mass. The amount of alcohol used is 2.5 parts by mass or less, 2 parts by mass or less, 1.5 parts by mass or less, 1.1 parts by mass or less, 0.8 parts by mass or less, or 0.6 parts by mass or less. May be good.
  • the amount of alcohol used includes the amount of surface cross-linking agent used.
  • the surface cross-linking step it is possible to carry out surface cross-linking on 100 parts by mass of the polymer particle group B1 using the above-mentioned surface cross-linking agent solution containing each amount of alcohol, for example, 0.6 parts by mass or more.
  • 100 parts by mass of the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing (for example, 0.6 to 5 parts by mass) alcohol.
  • the treatment temperature in the surface cross-linking step is appropriately set according to the surface cross-linking agent used, and may be 20 to 250 ° C.
  • the treatment temperature in the surface cross-linking step is preferably a temperature lower than the boiling point or decomposition temperature of the surface cross-linking agent.
  • the treatment time is preferably 1 to 200 minutes, more preferably 5 to 100 minutes, further preferably 5 to 60 minutes, and particularly preferably 5 to 45 minutes.
  • the surface-crosslinked polymer particle group may be classified by a sieve having an opening of 850 ⁇ m from the viewpoint of removing coarse particles.
  • the surface-crosslinked polymer particle group may be classified by a sieve having a mesh size of 45 ⁇ m from the viewpoint of removing extremely small fine powder.
  • the polymer particles (polymer) comprising a surface cross-linking step of subjecting the polymer particle group B1 that has passed through the sieve when the polymer particle group is classified by a sieve having a mesh size of 212 ⁇ m or less.
  • a method for producing the particle group B2) can be provided. It can be said that the method for producing the polymer particles is a method for producing fine powder or a method for cross-linking fine powder.
  • the method for producing polymer particles according to the present embodiment it is possible to obtain polymer particles having excellent water absorption characteristics under pressure as fine powders having excellent water absorption characteristics, and the fine powders can be effectively utilized. Can be done.
  • polymer particles having excellent CRC in addition to excellent water absorption characteristics under pressure can be obtained as fine powder having excellent water absorption characteristics.
  • the same conditions as the above-mentioned conditions for the surface cross-linking step of the water-absorbent resin particle manufacturing method according to the present embodiment can be arbitrarily set. Can be used.
  • a surface cross-linking agent solution containing each of the above-mentioned amounts of the surface cross-linking agent used for the surface cross-linking agent in the method for producing water-absorbent resin particles is used, and the opening is 212 ⁇ m.
  • the embodiment may include a step of subjecting 100 parts by mass of the polymer particle group B1 that has passed through the sieve to surface crosslink when the polymer particle group is classified by the following sieve, for example, 1 part by mass or more (for example, 1). It may be an embodiment including a step of subjecting 100 parts by mass of the polymer particle group B1 to surface cross-linking using a surface cross-linking agent solution containing ( ⁇ 10 parts by mass) of the surface cross-linking agent.
  • a surface cross-linking agent solution containing each of the above-mentioned amounts of the carbonate compound (for example, alkylene carbonate) used for the carbonate compound in the method for producing water-absorbent resin particles is used to open the openings.
  • the embodiment may include a step of surface cross-linking 100 parts by mass of the polymer particle group B1 that has passed through the sieve when the polymer particle group is classified with a sieve of 212 ⁇ m or less, for example, 0.5 parts by mass or more.
  • An embodiment may include a step of surface cross-linking 100 parts by mass of the polymer particle group B1 with a surface cross-linking agent solution containing a carbonate compound (for example, alkylene carbonate) of (for example, 0.5 to 10 parts by mass). ..
  • a carbonate compound for example, alkylene carbonate
  • the polymer particle group B1 that has passed through the sieve and the surface cross-linking agent are combined with a water-absorbent resin.
  • the embodiment may include a step of subjecting the polymer particle group B1 to surface cross-linking by mixing at each of the above-mentioned mixing temperatures in the method for producing particles.
  • the polymer particle group B1 and the surface cross-linking agent are heated to 20 ° C. or lower (
  • it may be an embodiment including a step of subjecting the polymer particle group B1 to surface cross-linking by mixing at 0 to 20 ° C.).
  • a polymer particle group that has passed through the sieve when the polymer particle group is classified by a sieve having a mesh size of 212 ⁇ m or less using a surface cross-linking agent solution containing isopropanol It may be an embodiment including a step of subjecting B1 to surface cross-linking.
  • the above-mentioned amounts of alcohol used in the method for producing the water-absorbent resin particles (the total mass of the surface cross-linking agent solution, or the surface cross-linking agent, alcohol and water which do not correspond to alcohol).
  • the polymer particle group is classified with a sieve having a mesh size of 212 ⁇ m or less by using a surface cross-linking agent solution containing alcohol (the amount used based on the total amount of the above and the amount used with respect to 100 parts by mass of the polymer particle group).
  • the embodiment may include a step of subjecting the polymer particle group B1 that has passed through the sieve to crosslink the surface.
  • a surface crosslinking agent solution containing 20% by mass or more (for example, 20 to 80% by mass) of alcohol may be provided, which may include a step of subjecting 100 parts by mass of the polymer particle group B1 to surface cross-linking. It may be an embodiment including a step of subjecting 100 parts by mass of the polymer particle group B1 to surface crosslinks using the above.
  • the polymer passed through the sieve.
  • the embodiment may include a step of subjecting the particle group B1 to surface crosslink, and the volume ratio of the alcohol to water may be each of the above-mentioned volume ratios in the method for producing the water-absorbent resin particles, for example, 0.25 or more ( For example, it may be 0.25 to 2.00).
  • the method for producing water-absorbent resin particles according to the present embodiment is a cross-linking weight for obtaining a polymer particle group to be classified using a sieve S1 or a sieve S2 before a classification step, a surface cross-linking step and a mixing step. It may be provided with a polymerization step to obtain a coalesced gel. In the polymerization step, for example, a monomer composition containing an ethylenically unsaturated monomer can be polymerized.
  • the monomer composition may contain water, an organic solvent, and the like.
  • the monomer composition may be a monomer aqueous solution.
  • Examples of the polymerization method of the monomer composition include an aqueous solution polymerization method and a bulk polymerization method. Among these, the aqueous solution polymerization method is preferable from the viewpoint that good water absorption characteristics (excellent water absorption characteristics under pressure, etc.) can be easily obtained and the polymerization reaction can be easily controlled. In the following, a case where the aqueous solution polymerization method is used as an example of the polymerization method will be described.
  • ethylenically unsaturated monomer a water-soluble ethylenically unsaturated monomer can be used.
  • the ethylenically unsaturated monomer include ⁇ , ⁇ -unsaturated carboxylic acids such as (meth) acrylate, maleic acid, maleic anhydride, and fumaric acid, and carboxylic acid-based monomers such as salts thereof; Nonionic monomers such as meta) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, polyethylene glycol mono (meth) acrylate; N, N -Amino group-containing unsaturated monomers such as diethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylamide, and quaternary products
  • the ethylenically unsaturated monomer preferably contains at least one (meth) acrylic acid compound selected from the group consisting of (meth) acrylic acid and salts thereof from the viewpoint of industrial availability.
  • the ethylenically unsaturated monomer may contain both (meth) acrylic acid and a salt of (meth) acrylic acid.
  • salts of ⁇ , ⁇ -unsaturated carboxylic acid include alkali metal salts (sodium salt, potassium salt, etc.), alkaline earth metal salts (calcium salt, etc.) and the like.
  • the ethylenically unsaturated monomer having an acid group may have the acid group neutralized in advance with an alkaline neutralizer.
  • alkaline neutralizing agent include alkali metal salts such as sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide and potassium carbonate; ammonia and the like.
  • the alkaline neutralizer may be used in the form of an aqueous solution in order to simplify the neutralization operation.
  • the acid group may be neutralized before the polymerization of the ethylenically unsaturated monomer as a raw material, or during or after the polymerization.
  • the degree of neutralization of the ethylenically unsaturated monomer by the alkaline neutralizer is from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained by increasing the osmotic pressure, and the excess alkaline neutralizer. From the viewpoint of suppressing defects caused by the presence of, 10 to 100 mol%, 30 to 90 mol%, 40 to 85 mol%, or 50 to 80 mol% is preferable.
  • the "neutralization degree” is the neutralization degree for all the acid groups of the ethylenically unsaturated monomer.
  • the content of the (meth) acrylic acid compound is preferably in the following range based on the total mass of the monomer composition.
  • the content of the (meth) acrylic acid compound is 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, or from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. , 35% by mass or more is preferable.
  • the content of the (meth) acrylic acid compound is 60% by mass or less, 55% by mass or less, 50% by mass or less, less than 50% by mass from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained. It is preferably 45% by mass or less, or 40% by mass or less. From these viewpoints, the content of the (meth) acrylic acid compound is preferably 10 to 60% by mass.
  • the content of the (meth) acrylic acid compound is the total amount of the monomers contained in the monomer composition and / or the total amount of the ethylenically unsaturated monomer contained in the monomer composition. The following range is preferable with reference to.
  • the content of the (meth) acrylic acid compound is preferably 50 mol% or more, 70 mol% or more, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more.
  • the monomer contained in the monomer composition and / or the ethylenically unsaturated monomer contained in the monomer composition is substantially composed of a (meth) acrylic acid compound (substantially).
  • 100 mol% of the monomer contained in the monomer composition and / or the ethylenically unsaturated monomer contained in the monomer composition is a (meth) acrylic acid compound). It may be.
  • the content of the structural unit derived from the (meth) acrylic acid compound is the above-mentioned (meth) acrylic acid based on the total mass of the structural units constituting the water-absorbent resin particles.
  • the content of the compound (the total amount of monomers contained in the monomer composition and / or the total amount of ethylenically unsaturated monomers contained in the monomer composition was used as a reference (meth). ) Content of acrylic acid compound) is preferably in each of the above ranges.
  • the monomer composition may contain a polymerization initiator.
  • the polymerization of the monomer contained in the monomer composition may be started by adding a polymerization initiator to the monomer composition and, if necessary, heating, irradiating with light or the like.
  • the polymerization initiator include a photopolymerization initiator and a radical polymerization initiator, and a water-soluble radical polymerization initiator is preferable.
  • the polymerization initiator preferably contains at least one selected from the group consisting of azo compounds and peroxides from the viewpoint of easily obtaining good water absorption characteristics (water absorption characteristics under pressure, etc.), and contains peroxides. Is more preferable.
  • Examples of the azo compound include 2,2'-azobis [2- (N-phenylamidino) propane] dihydrochloride and 2,2'-azobis ⁇ 2- [N- (4-chlorophenyl) amidino] propane ⁇ dihydrochloride.
  • the azo compounds are 2,2'-azobis (2-methylpropionamide) dihydrochloride and 2,2'-azobis (2-) from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained.
  • Peroxides include persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate; methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, t-butyl. Examples thereof include organic peroxides such as peroxyacetate, t-butylperoxyisobutyrate, and t-butylperoxypivalate.
  • the peroxide preferably contains at least one selected from the group consisting of potassium persulfate, ammonium persulfate, and sodium persulfate from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained.
  • the content of the polymerization initiator is preferably in the following range with respect to 1 mol of the (meth) acrylic acid compound.
  • the content of the polymerization initiator is 0.001 mmol or more, 0.003 mmol or more, 0 from the viewpoint of easily obtaining good water absorption characteristics (water absorption characteristics under pressure, etc.) and shortening the polymerization reaction time. .015 mmol or more, 0.03 mmol or more, 0.06 mmol or more, 0.08 mmol or more, 0.1 mmol or more, 0.15 mmol or more, 0.2 mmol or more, or 0.25 mmol or more is preferable. ..
  • the content of the polymerization initiator is 5 mmol or less, 4 mmol or less, 2 mmol or less from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained and a rapid polymerization reaction can be easily avoided. It is preferably 1 mmol or less, or 0.8 mmol or less. From these viewpoints, the content of the polymerization initiator is preferably 0.001 to 5 mmol.
  • the monomer composition may contain a reducing agent.
  • the reducing agent include sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, L-ascorbic acid and the like.
  • a polymerization initiator and a reducing agent may be used in combination.
  • the monomer composition may contain an oxidizing agent.
  • the oxidizing agent include hydrogen peroxide, sodium perborate, perphosphoric acid and salts thereof, potassium permanganate and the like.
  • the monomer composition may contain an internal cross-linking agent.
  • the obtained cross-linking polymer can have a cross-linking structure by the internal cross-linking agent in addition to the self-cross-linking structure by the polymerization reaction as the internal cross-linking structure.
  • Examples of the internal cross-linking agent include compounds having two or more reactive functional groups (for example, polymerizable unsaturated groups).
  • Examples of the internal cross-linking agent include di or tri (meth) acrylic acid esters of polyols such as (poly) ethylene glycol, (poly) propylene glycol, trimethylolpropane, glycerin polyoxyethylene glycol, polyoxypropylene glycol, and (poly) glycerin.
  • unsaturated polyesters obtained by reacting the above polyol with an unsaturated acid (maleic acid, fumaric acid, etc.); (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin.
  • Glycidyl group-containing compounds such as diglycidyl ether and glycidyl (meth) acrylate; bisacrylamides such as N, N'-methylenebis (meth) acrylamide; di or tri (meth) obtained by reacting polyepoxide with (meth) acrylic acid.
  • the internal cross-linking agent has good water absorption characteristics (water absorption characteristics under pressure, etc.).
  • polyethylene glycol di (meth) acrylate trimethylolpropantri (meth) acrylate
  • polyethylene glycol diglycidyl ether trimethylolpropantri (meth) acrylate
  • polyethylene glycol diglycidyl ether ethylene glycol diglycidyl ether
  • polypropylene glycol diglycidyl ether ethylene glycol diglycidyl ether
  • poly glycerinji preferably contains at least one selected from the group consisting of glycidyl ethers.
  • the content of the internal cross-linking agent is preferably in the following range with respect to 1 mol of the (meth) acrylic acid compound.
  • the content of the internal cross-linking agent is 0.01 mmol or more, 0.05 mmol or more, 0.08 mmol or more, 0.1 mmol or more from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained. , 0.15 mmol or more, or 0.2 mmol or more is preferable.
  • the content of the internal cross-linking agent is preferably 10 mmol or less, 8 mmol or less, 5 mmol or less, 3 mmol or less, or 2 mmol or less from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained. .. From these viewpoints, the content of the internal cross-linking agent is preferably 0.01 to 10 mmol.
  • the monomer composition may contain additives such as a chain transfer agent, a thickener, and an inorganic filler as components different from the above-mentioned components.
  • a chain transfer agent include thiols, thiol acids, secondary alcohols, hypophosphorous acid, phosphorous acid, achlorine and the like.
  • the thickener include carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyethylene glycol, polyacrylic acid, neutralized polyacrylic acid, polyacrylamide and the like.
  • the inorganic filler include metal oxides, ceramics, and viscous minerals.
  • a polymerization method for aqueous solution polymerization As a polymerization method for aqueous solution polymerization, a static polymerization method in which the monomer composition is polymerized without stirring (for example, a static state); a stirring polymerization method in which the monomer composition is polymerized while stirring in a reaction apparatus. And so on.
  • a static polymerization method when the polymerization is completed, a single block-shaped gel occupying substantially the same volume as the monomer composition present in the reaction vessel is obtained.
  • the form of polymerization may be batch, semi-continuous, continuous, or the like.
  • the polymerization reaction can be carried out while continuously supplying the monomer composition to the continuous polymerization apparatus to continuously obtain a gel.
  • the polymerization temperature varies depending on the polymerization initiator used, but from the viewpoint of rapidly advancing the polymerization, increasing the productivity by shortening the polymerization time, removing the heat of polymerization, and facilitating the smooth reaction, 0 to 0 to It is preferably 130 ° C. or 10 to 110 ° C.
  • the maximum value of the polymerization temperature may be 25 ° C. or higher, 30 ° C. or higher, 40 ° C. or higher, 50 ° C. or higher, or 60 ° C. or higher.
  • the maximum value of the polymerization temperature may be 110 ° C. or lower, 105 ° C. or lower, 100 ° C. or lower, or 95 ° C. or lower.
  • the maximum value of the polymerization temperature may be 25 to 110 ° C.
  • the polymerization time is appropriately set depending on the type and amount of the polymerization initiator used, the reaction temperature, and the like, but is preferably 1 to 200 minutes or 5 to 100 minutes.
  • the method for producing the water-absorbent resin particles according to the present embodiment includes a rough crushing step of coarsely crushing the crosslinked polymer gel obtained in the polymerization step to obtain a coarse crushed product (for example, a gel coarse crushed product), and a drying of the coarse crushed product.
  • a drying step of obtaining a dried product and a crushing step of crushing the dried product to obtain a crushed product may be provided.
  • These dried products or pulverized products can be used as a polymer particle group to be classified using a sieve S1 or a sieve S2.
  • a kneader pressurized kneader, double-armed kneader, etc.
  • a meat chopper a cutter mill, a pharma mill, or the like
  • a pharma mill a pharma mill, or the like
  • a dried product for example, gel dried product
  • a dried product can be obtained by removing liquid components (water, etc.) in the pyroclastic material by heating and / or blowing air.
  • the drying method may be natural drying, heat drying, blast drying, vacuum drying or the like.
  • the drying temperature is, for example, 70 to 250 ° C.
  • Crushers in the crushing process include roller mills (roll mills), stamp mills, jet mills, high-speed rotary crushers (hammer mills, pin mills, rotor beater mills, etc.), container-driven mills (rotary mills, vibration mills, planetary mills, etc.). ) And so on.
  • the water-absorbent resin particles according to the present embodiment can be obtained by the method for producing the water-absorbent resin particles according to the present embodiment.
  • the water-absorbent resin particles according to the present embodiment preferably have a structural unit derived from an ethylenically unsaturated monomer from the viewpoint of easily obtaining excellent water-absorbing properties under pressure.
  • the water-absorbent resin particles according to the present embodiment are crosslinked polymers (crosslinked weights having structural units derived from ethylenically unsaturated monomers) obtained by polymerizing a monomer containing an ethylenically unsaturated monomer. It is preferable to include coalescence).
  • the above-mentioned ethylenically unsaturated monomer related to the monomer composition in the polymerization step can be used.
  • the ethylenically unsaturated monomer preferably contains at least one compound selected from the group consisting of (meth) acrylic acid and a salt thereof from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
  • Examples of the shape of the water-absorbent resin particles according to the present embodiment include substantially spherical, crushed, and granular shapes.
  • the water-absorbent resin particles according to the present embodiment may be any water-absorbent resin particles as long as they can retain water, and the liquid to be absorbed may contain water.
  • the water-absorbent resin particles according to the present embodiment can absorb body fluids such as urine, sweat, and blood (for example, menstrual blood).
  • the water-absorbent resin particles according to the present embodiment can be used as a constituent component of the absorber.
  • This embodiment can be used in the fields of, for example, sanitary materials such as disposable diapers and sanitary products; agricultural and horticultural materials such as water retention agents and soil conditioners; and industrial materials such as water stop agents and dew condensation inhibitors.
  • the water-absorbent resin particles according to the present embodiment are gel stabilizers; metal chelating agents (ethylenediaminetetraacetic acid and salts thereof, diethylenetriamine-5 acetic acid and salts thereof (for example, diethylenetriamine-5sodium acetate), etc.); fluidity improvers (lubricant).
  • metal chelating agents ethylenediaminetetraacetic acid and salts thereof, diethylenetriamine-5 acetic acid and salts thereof (for example, diethylenetriamine-5sodium acetate), etc.
  • fluidity improvers lubricant
  • Other components such as may be further contained.
  • Other components may be located inside, on the surface, or both of crosslinked polymers having structural units derived from ethylenically unsaturated monomers.
  • the water-absorbent resin particles according to the present embodiment may contain inorganic particles arranged on the surface of a crosslinked polymer having a structural unit derived from an ethylenically unsaturated monomer.
  • the inorganic particles can be arranged on the surface of the crosslinked polymer.
  • the inorganic particles include silica particles such as amorphous silica.
  • the CRC of the water-absorbent resin particles according to this embodiment is preferably in the following range.
  • the CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 30 g / g or more, particularly preferably 31 g / g or more, extremely preferably 32 g / g or more, and very preferably 33 g / g or more.
  • 35 g / g or more is even more preferable
  • 38 g / g or more is further preferable
  • 40 g / g or more is particularly preferable
  • 45 g / g or more is extremely preferable.
  • the CRC is preferably 60 g / g or less, more preferably 55 g / g or less, further preferably 50 g / g or less, and particularly preferably 46 g / g or less. From these viewpoints, the CRC is preferably 20 to 60 g / g, more preferably 20 to 55 g / g, and even more preferably 30 to 50 g / g.
  • the absorption ratio (AAP) of the water-absorbent resin particles according to the present embodiment under pressurization of 4.83 kPa is preferably 8.3 g / g or more, more preferably 8.5 g / g or more, and further preferably 9.0 g / g or more.
  • 10.0 g / g or more is particularly preferable, 15.0 g / g or more is extremely preferable, 16.0 g / g or more is very preferable, 17.0 g / g or more is even more preferable, and 18.0 g / g or more is preferable. Is more preferable.
  • the upper limit of the absorption ratio (AAP) of the water-absorbent resin particles under pressure of 4.83 kPa is, for example, 40.0 g / g or less, 35.0 g / g or less, 30.0 g / g or less, 25.0 g / g or less, Alternatively, it may be 20.0 g / g or less.
  • the absorber according to the present embodiment contains the water-absorbent resin particles according to the present embodiment.
  • the absorber according to the present embodiment may contain a fibrous substance, for example, a mixture containing water-absorbent resin particles and the fibrous substance.
  • the structure of the absorber may be, for example, a structure in which the water-absorbent resin particles and the fibrous material are uniformly mixed, and the water-absorbent resin particles are sandwiched between the fibrous material formed in a sheet or layer. It may be a configuration or another configuration.
  • the fibrous material examples include finely pulverized wood pulp; cotton; cotton linter; rayon; cellulosic fibers such as cellulose acetate; synthetic fibers such as polyamide, polyester and polyolefin; and a mixture of these fibers.
  • the fibrous material may be used alone or in combination of two or more.
  • hydrophilic fibers can be used as the fibrous material.
  • the mass ratio of the water-absorbent resin particles in the absorber may be 2 to 100% by mass, 10 to 80% by mass, or 20 to 60% by mass with respect to the total of the water-absorbent resin particles and the fibrous material.
  • the content of the water-absorbent resin particles in the absorber is preferably 100 to 1000 g, more preferably 150 to 800 g, and even more preferably 200 to 700 g per 1 m 2 of the absorber from the viewpoint of easily obtaining sufficient water absorption characteristics.
  • the content of the fibrous substance in the absorber is preferably 50 to 800 g, more preferably 100 to 600 g, and even more preferably 150 to 500 g per 1 m 2 of the absorber from the viewpoint of easily obtaining sufficient water absorption characteristics.
  • the fibers may be adhered to each other by adding an adhesive binder to the fibrous material.
  • the adhesive binder include heat-sealing synthetic fibers, hot melt adhesives, and adhesive emulsions.
  • the adhesive binder may be used alone or in combination of two or more.
  • the heat-bondable synthetic fiber examples include a total fusion type binder such as polyethylene, polypropylene, and an ethylene-propylene copolymer; a non-total fusion type binder having a side-by-side or core-sheath structure of polypropylene and polyethylene.
  • a total fusion type binder such as polyethylene, polypropylene, and an ethylene-propylene copolymer
  • non-total fusion type binder having a side-by-side or core-sheath structure of polypropylene and polyethylene.
  • hot melt adhesives examples include ethylene-vinyl acetate copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, and styrene-ethylene-propylene-styrene block copolymer.
  • a mixture of a base polymer such as amorphous polypropylene and a tackifier, a plasticizer, an antioxidant and the like.
  • Examples of the adhesive emulsion include polymers of at least one monomer selected from the group consisting of methyl methacrylate, styrene, acrylonitrile, 2-ethylhexyl acrylate, butyl acrylate, butadiene, ethylene, and vinyl acetate.
  • the absorber according to the present embodiment may contain an inorganic powder (for example, amorphous silica), a deodorant, an antibacterial agent, a fragrance, and the like.
  • an inorganic powder for example, amorphous silica
  • the absorber may contain inorganic powder in addition to the inorganic particles in the water-absorbent resin particles.
  • the shape of the absorber according to the present embodiment may be, for example, a sheet shape.
  • the thickness of the absorber (for example, the thickness of the sheet-shaped absorber) may be, for example, 0.1 to 20 mm and 0.3 to 15 mm.
  • the absorbent article according to the present embodiment includes an absorber according to the present embodiment.
  • the absorbent article according to the present embodiment is a core wrap that retains the shape of the absorber; a liquid permeable sheet that is arranged on the outermost side of the side where the liquid to be absorbed enters; Examples thereof include a liquid permeable sheet arranged on the outermost side on the opposite side.
  • absorbent articles include diapers (for example, paper diapers), toilet training pants, incontinence pads, sanitary materials (sanitary napkins, tampons, etc.), sweat pads, pet sheets, simple toilet materials, animal excrement treatment materials, and the like. ..
  • FIG. 1 is a cross-sectional view showing an example of an absorbent article.
  • the absorbent article 100 shown in FIG. 1 includes an absorber 10, core wraps 20a and 20b, a liquid permeable sheet 30, and a liquid permeable sheet 40.
  • the liquid permeable sheet 40, the core wrap 20b, the absorbent body 10, the core wrap 20a, and the liquid permeable sheet 30 are laminated in this order.
  • the absorber 10 has a water-absorbent resin particle 10a according to the present embodiment and a fiber layer 10b containing a fibrous material.
  • the water-absorbent resin particles 10a are dispersed in the fiber layer 10b.
  • the core wrap 20a is arranged on one side of the absorber 10 (upper side of the absorber 10 in FIG. 1) in contact with the absorber 10.
  • the core wrap 20b is arranged on the other side of the absorber 10 (lower side of the absorber 10 in FIG. 1) in contact with the absorber 10.
  • the absorber 10 is arranged between the core wrap 20a and the core wrap 20b.
  • Examples of the core wraps 20a and 20b include tissues, non-woven fabrics and the like.
  • the core wrap 20a and the core wrap 20b have, for example, a main surface having the same size as the absorber 10.
  • the liquid permeable sheet 30 is arranged on the outermost side on the side where the liquid to be absorbed enters.
  • the liquid permeable sheet 30 is arranged on the core wrap 20a in contact with the core wrap 20a.
  • Examples of the liquid permeable sheet 30 include non-woven fabrics made of synthetic resins such as polyethylene, polypropylene, polyester and polyamide, and porous sheets.
  • the liquid permeable sheet 40 is arranged on the outermost side of the absorbent article 100 on the opposite side of the liquid permeable sheet 30.
  • the liquid impermeable sheet 40 is arranged under the core wrap 20b in contact with the core wrap 20b.
  • liquid impermeable sheet 40 examples include a sheet made of a synthetic resin such as polyethylene, polypropylene, and polyvinyl chloride, and a sheet made of a composite material of these synthetic resins and a non-woven fabric.
  • the liquid permeable sheet 30 and the liquid permeable sheet 40 have, for example, a main surface wider than the main surface of the absorber 10, and the outer edges of the liquid permeable sheet 30 and the liquid permeable sheet 40 are It extends around the absorber 10 and the core wraps 20a, 20b.
  • the magnitude relationship between the absorbent body 10, the core wraps 20a and 20b, the liquid permeable sheet 30, and the liquid permeable sheet 40 is not particularly limited, and is appropriately adjusted according to the use of the absorbent article and the like. Further, the method of retaining the shape of the absorber 10 using the core wraps 20a and 20b is not particularly limited, and as shown in FIG. 1, the absorber may be wrapped by a plurality of core wraps, and the absorber is wrapped by one core wrap. But it may be.
  • the present embodiment it is possible to provide a liquid absorbing method using the water-absorbent resin particles, the absorbent body or the absorbent article according to the present embodiment.
  • the liquid absorbing method according to the present embodiment includes a step of bringing the liquid to be absorbed into contact with the water-absorbent resin particles, the absorber or the absorbent article according to the present embodiment.
  • the present invention is not limited to the following experimental examples. If the temperature at the time of the experimental operation is not described below, the experimental operation can be performed at room temperature.
  • the obtained hydrogel was sequentially put into a meat chopper 12VR-750SDX manufactured by Kiren Royal Co., Ltd. and subdivided.
  • the diameter of the hole in the plate located at the tip of the meat chopper was 6.4 mm.
  • This subdivided particulate hydrogel was spread and placed on a wire mesh having an opening of 0.8 cm ⁇ 0.8 cm, and then dried with hot air at 160 ° C. for 60 minutes to obtain a dried product.
  • the dried product was crushed using a centrifugal crusher (Resch, ZM200, screen diameter 1 mm, 6000 rpm), and the amorphous crushed polymer particles ( ⁇ ) (dry weight loss) were passed through a sieve having an opening of 850 ⁇ m. 1.8% by mass) was obtained.
  • the CRC of the polymer particles ( ⁇ ) was 39 g / g
  • the medium particle size was 352 ⁇ m
  • the proportion of polymer particles as a fraction) was 30% by mass.
  • the obtained hydrogel was sequentially put into a meat chopper 12VR-750SDX manufactured by Kiren Royal Co., Ltd. and subdivided.
  • the diameter of the hole in the plate located at the tip of the meat chopper was 6.4 mm.
  • This subdivided particulate hydrogel was spread and placed on a wire mesh having an opening of 0.8 cm ⁇ 0.8 cm, and then dried with hot air at 160 ° C. for 60 minutes to obtain a dried product.
  • the dried product was crushed using a centrifugal crusher (Resch, ZM200, screen diameter 1 mm, 12000 rpm), and the amorphous crushed polymer particles ( ⁇ ) (dry weight loss) were passed through a sieve having an opening of 850 ⁇ m. : 1.2% by mass) was obtained.
  • the CRC of the polymer particles ( ⁇ ) was 51 g / g
  • the medium particle size was 254 ⁇ m
  • the mass ratio in the particle size range of “more than 0 ⁇ m and less than 180 ⁇ m” passeded through a sieve having an opening of 180 ⁇ m).
  • the proportion of polymer particles as a fraction) was 35% by mass.
  • the mass ratio of the polymer particles ( ⁇ ) and the polymer particles ( ⁇ ) in the particle size range of “more than 0 ⁇ m and less than 180 ⁇ m” was calculated by the following procedure. Using a continuous fully automatic sonic vibration type sieving measuring instrument (Robot Shifter RPS-205, manufactured by Seishin Enterprise Co., Ltd.), JIS standard meshes of 850 ⁇ m, 500 ⁇ m, 425 ⁇ m, 300 ⁇ m, 250 ⁇ m, 180 ⁇ m and 106 ⁇ m, and a saucer. The particle size distribution of 10 g of the polymer particles was measured in.
  • the mass of the particles remaining on each sieve was calculated as a mass percentage with respect to the total amount, and the particle size distribution was obtained.
  • the mass ratio in the particle size range of "more than 0 ⁇ m and less than 180 ⁇ m" was calculated based on the total amount of particles remaining on the sieve and the saucer having a mesh size of 180 ⁇ m.
  • the medium particle diameters of the polymer particles ( ⁇ ) and the polymer particles ( ⁇ ) were calculated by the following procedure. With respect to the above particle size distribution, by integrating the masses of the particles remaining on the sieve in order from the one with the largest particle diameter, the relationship between the mesh size of the sieve and the integrated value of the mass percentage of the particles remaining on the sieve is logarithmic. Plotted on probability paper. By connecting the plots on the probability paper with a straight line, the particle size corresponding to the cumulative mass percentage of 50% by mass was obtained as the medium particle size.
  • Example 2 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1b) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 3 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1c) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 4 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1d) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 5 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1e) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 6 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1f) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 7 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1g) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 8 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1h) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 9 After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1i) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 10 After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-2a) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 11 After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-2b) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 12 After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-1e) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 13 After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-1f) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
  • Example 15 90 parts by mass of polymer particles (X12) and 10 parts by mass of polymer particles (X13) are put into a 100 mL mayonnaise bottle, and then uniformly mixed by shaking with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. Water-absorbent resin particles were obtained.
  • Example 17 90 parts by mass of polymer particles (X22) and 10 parts by mass of polymer particles (X23) are put into a 100 mL mayonnaise bottle, and then uniformly mixed by shaking with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. Water-absorbent resin particles were obtained.
  • the CRC was measured by the following procedure with reference to the EDANA method (NWSP 241.0.R2 (15), page.769-778).
  • the CRC of the above-mentioned water-absorbent resin particles ( ⁇ ) and water-absorbent resin particles ( ⁇ ) was also measured in the same manner. The measurement was carried out in an environment where the temperature was 25 ° C. ⁇ 2 ° C. and the humidity was 50% ⁇ 10%.
  • a non-woven fabric with a size of 60 mm x 170 mm (product name: Heat Pack MWA-18, manufactured by Nippon Paper Papylia Co., Ltd.) was folded in half in the longitudinal direction to adjust the size to 60 mm x 85 mm.
  • a 60 mm ⁇ 85 mm non-woven fabric bag was produced by crimping the non-woven fabrics to each other on both sides extending in the longitudinal direction with a heat seal (a crimped portion having a width of 5 mm was formed on both sides along the longitudinal direction). 0.2 g of the particles to be measured were precisely weighed and contained inside the non-woven fabric bag. Then, the non-woven fabric bag was closed by crimping the remaining one side extending in the lateral direction with a heat seal.
  • the entire non-woven fabric bag was completely moistened by floating the non-woven fabric bag on 1000 g of physiological saline contained in a stainless steel vat (240 mm ⁇ 320 mm ⁇ 45 mm) without folding the non-woven fabric bag.
  • a stainless steel vat 240 mm ⁇ 320 mm ⁇ 45 mm
  • the non-woven fabric bag was taken out from the physiological saline solution. Then, the non-woven fabric bag was put in a centrifuge (manufactured by Kokusan Co., Ltd., model number: H-122). After the centrifugal force in the centrifuge reached 250 G, the non-woven fabric bag was dehydrated for 3 minutes. After dehydration, the mass Ma of the non-woven fabric bag containing the mass of the gel was weighed. The non-woven fabric bag was subjected to the same operation as described above without accommodating the particles to be measured, and the mass Mb of the non-woven fabric bag was measured.
  • AAP absorption magnification
  • the weight 112 includes a disc portion 112a, a rod-shaped portion 112b extending from the center of the disc portion 112a in a direction perpendicular to the disc portion 112a, and a cylindrical portion 112c having a through hole inserted into the rod-shaped portion 112b in the center. have.
  • the disk portion 112a of the weight 112 has a diameter substantially equal to the inner diameter of the cylinder 114 so that it can be moved in the longitudinal direction of the cylinder 114 inside the cylinder 114.
  • the diameter of the cylindrical portion 112c is smaller than the diameter of the disc portion 112a.
  • the cylinder 114 Although one end of the cylinder 114 is open, it is shielded by a wire mesh 116, and the other end of the cylinder 114 is open so that the weight 112 can be inserted. Inside the cylinder 114, 0.90 g of particles 120 to be measured were uniformly sprayed on the wire mesh 116. Then, after the weight 112 is inserted into the cylinder 114 and the weight 112 is placed on the measurement target particle 120, the total mass of the measurement device 110 (the total mass of the measurement device 110 and the measurement target particle 120 before liquid absorption). Wa [g] was measured.
  • the above-mentioned measuring device 110 was placed on the filter paper 150 to absorb the liquid under a load. After 1 hour, the measuring device 110 was lifted, and the total mass of the measuring device 110 (total mass of the measuring device 110 and the measurement target particle 120 after absorbing the liquid) Wb [g] was measured.
  • each of the plurality of polymer particle groups obtained by classification was surface-crosslinked and then mixed.
  • a plurality of polymer particle groups obtained by classifying after the surface cross-linking without classifying before the surface cross-linking were mixed. It can be seen that excellent water absorption characteristics under pressure can be obtained.
  • the mixing temperature of the surface cross-linking agent and the amount of alcohol used in the surface cross-linking applied to the polymer particle group remaining on the sieve having a mesh size of 212 ⁇ m or less are under pressure. It can be seen that it does not significantly affect the water absorption characteristics of.
  • surface cross-linking applied to the polymer particle group passing through a sieve having a mesh size of 212 ⁇ m or less surface cross-linking applied to the polymer particle group passing through a sieve having a mesh size of 212 ⁇ m or less. It can be seen that the mixing temperature of the surface cross-linking agent and the amount of alcohol used in the above contribute greatly to the water absorption characteristics under pressure.
  • the amount of the surface cross-linking agent used in the surface cross-linking applied to the polymer particle group passing through the sieve having a mesh size of 212 ⁇ m or less is the water absorption characteristic under pressure. It can be seen that it greatly contributes to.
  • 10 Absorbent, 10a ... Water-absorbent resin particles, 10b ... Fiber layer, 20a, 20b ... Core wrap, 30 ... Liquid permeable sheet, 40 ... Liquid permeable sheet, 100 ... Absorbent article, 110 ... Measuring device, 112 ... Weight, 112a ... Disc, 112b ... Rod, 112c ... Cylindrical, 114 ... Cylindrical, 116 ... Wire mesh, 120 ... Particles to be measured, 130 ... Stainless steel, 140 ... Glass filter, 150 ... Filter paper.

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Abstract

This method for manufacturing water absorbing resin particles comprises a step for obtaining water absorbing resin particles 10a by mixing together a polymeric particle group A2 and a polymeric particle group B2. The polymeric particle group A2 is obtained by performing surface crosslinking on a polymeric particle group A1 which is left on a sieve S1, with a mesh opening of 212 μm or smaller, when a polymeric particle group has been sorted with the sieve S1. The polymer particle group B2 is obtained by performing surface crosslinking on a polymer particle group B1 that has passed through a sieve S2, with a mesh opening of 212 μm or smaller, when a polymer particle group is sorted with the sieve S2.

Description

吸水性樹脂粒子の製造方法及び重合体粒子の製造方法Method for producing water-absorbent resin particles and method for producing polymer particles
　本発明は、吸水性樹脂粒子の製造方法及び重合体粒子の製造方法に関する。 The present invention relates to a method for producing water-absorbent resin particles and a method for producing polymer particles.
　従来、水を主成分とする液体（例えば尿）を吸収するための吸収性物品には、吸水性樹脂粒子を含有する吸収体が用いられている。吸収体中の吸水性樹脂粒子には、吸水量が高いことに加えて液拡散性が優れていることが求められる。液拡散性は、一般的に、吸水性樹脂粒子中の微粉の割合が大きくなると低下する傾向にある。すなわち、吸水性樹脂粒子中の微粉は、膨潤すると液体が拡散するための通り道を塞ぎやすく、いわゆる「ゲルブロッキング」を起こしやすい。吸水性樹脂粒子がゲルブロッキングを起こしてしまうと、吸収体中における液体の拡散性が悪くなるため、本来の吸収体の性能が充分に発揮されずに液体の逆戻り量も多くなる。そのため、吸水性樹脂粒子から微粉を除去することが行われている（例えば、下記特許文献１参照）。 Conventionally, an absorber containing water-absorbent resin particles has been used as an absorbent article for absorbing a liquid (for example, urine) containing water as a main component. The water-absorbent resin particles in the absorber are required to have excellent liquid diffusivity in addition to having a high water absorption amount. The liquid diffusibility generally tends to decrease as the proportion of fine powder in the water-absorbent resin particles increases. That is, the fine powder in the water-absorbent resin particles tends to block the path for the liquid to diffuse when swollen, and tends to cause so-called "gel blocking". When the water-absorbent resin particles cause gel blocking, the diffusibility of the liquid in the absorber deteriorates, so that the original performance of the absorber is not sufficiently exhibited and the amount of liquid reversion increases. Therefore, fine powder is removed from the water-absorbent resin particles (see, for example, Patent Document 1 below).
特表２０１０－５２２７７９号公報Special Table 2010-522779
　一方、上述のように微粉を除去すると、製品になる吸水性樹脂粒子が減ることから、生産性を悪化させないためには、微粉を製品に活用することが求められる。そのため、微粉を活用しつつ優れた吸水特性を得ることが求められ、吸水特性としては、例えば、吸水性樹脂粒子が加圧される使用態様を考慮して、加圧下における優れた吸水特性を得ることが求められる。 On the other hand, if the fine powder is removed as described above, the number of water-absorbent resin particles that become the product decreases. Therefore, in order not to deteriorate the productivity, it is required to utilize the fine powder in the product. Therefore, it is required to obtain excellent water absorption characteristics while utilizing fine powder, and as the water absorption characteristics, for example, in consideration of the usage mode in which the water absorption resin particles are pressurized, excellent water absorption characteristics under pressure are obtained. Is required.
　本発明の一側面は、微粉を活用しつつ、加圧下における優れた吸水特性を有する吸水性樹脂粒子を得ることが可能な吸水性樹脂粒子の製造方法を提供することを目的とする。本発明の他の一側面は、吸水特性に優れた微粉として、加圧下における優れた吸水特性を有する重合体粒子を得ることが可能な重合体粒子の製造方法を提供することを目的とする。 One aspect of the present invention is to provide a method for producing water-absorbent resin particles capable of obtaining water-absorbent resin particles having excellent water-absorbing properties under pressure while utilizing fine powder. Another aspect of the present invention is to provide a method for producing polymer particles capable of obtaining polymer particles having excellent water absorption characteristics under pressure as fine powder having excellent water absorption characteristics.
　本発明者は、目開き２１２μｍ以下の篩を通過する微粉を活用することに着目した上で、このような微粉を用いて、加圧下における優れた吸水特性を有する吸水性樹脂粒子を得ることに着想した。これに対し、本発明者は、目開き２１２μｍ以下の篩で分級された複数の重合体粒子群のそれぞれに対して表面架橋を施した後、微粉に対して表面架橋を施して得られる一の重合体粒子群と、他の重合体粒子群とを混合することにより、微粉を活用しつつ、加圧下における優れた吸水特性を有する吸水性樹脂粒子を得ることができることを見出した。 The present inventor focused on utilizing fine powder that passes through a sieve having a mesh size of 212 μm or less, and obtained water-absorbent resin particles having excellent water absorption characteristics under pressure by using such fine powder. I was inspired. On the other hand, the present inventor obtains one obtained by subjecting each of a plurality of polymer particle groups classified by a sieve having a mesh size of 212 μm or less to surface cross-linking and then subjecting fine powder to surface cross-linking. It has been found that by mixing the polymer particle group with another polymer particle group, it is possible to obtain water-absorbent resin particles having excellent water-absorbing properties under pressure while utilizing fine powder.
　本発明の一側面は、目開き２１２μｍ以下の篩Ｓ１で重合体粒子群を分級した際に当該篩Ｓ１上に残存する重合体粒子群Ａ１に表面架橋を施して得られる重合体粒子群Ａ２と、目開き２１２μｍ以下の篩Ｓ２で重合体粒子群を分級した際に当該篩Ｓ２を通過した重合体粒子群Ｂ１に表面架橋を施して得られる重合体粒子群Ｂ２と、を混合することにより吸水性樹脂粒子を得る工程を備える、吸水性樹脂粒子の製造方法を提供する。 One aspect of the present invention is the polymer particle group A2 obtained by subjecting the polymer particle group A1 remaining on the sieve S1 to surface cross-linking when the polymer particle group is classified by the sieve S1 having a mesh size of 212 μm or less. Water absorption by mixing with the polymer particle group B2 obtained by subjecting the polymer particle group B1 that has passed through the sieve S2 to surface cross-linking when the polymer particle group is classified by the sieve S2 having a mesh size of 212 μm or less. Provided is a method for producing a water-absorbent resin particle, which comprises a step of obtaining the sex resin particle.
　このような吸水性樹脂粒子の製造方法によれば、微粉を活用しつつ、加圧下における優れた吸水特性を有する吸水性樹脂粒子を得ることができる。 According to such a method for producing water-absorbent resin particles, it is possible to obtain water-absorbent resin particles having excellent water-absorbing properties under pressure while utilizing fine powder.
　また、本発明者は、目開き２１２μｍ以下の篩を通過する微粉に対して特定の条件で表面架橋を施すことにより、加圧下における優れた吸水特性を有する重合体粒子を得ることができることを見出した。 Further, the present inventor has found that polymer particles having excellent water absorption characteristics under pressure can be obtained by subjecting fine powder passing through a sieve having a mesh size of 212 μm or less to surface cross-linking under specific conditions. It was.
　本発明の他の一側面は、目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した重合体粒子群Ｂ１と、表面架橋剤と、を０～２０℃で混合して前記重合体粒子群Ｂ１に表面架橋を施す工程を備える、重合体粒子の製造方法を提供する。 Another aspect of the present invention is that when the polymer particle group is classified by a sieve having a mesh size of 212 μm or less, the polymer particle group B1 that has passed through the sieve and the surface cross-linking agent are mixed at 0 to 20 ° C. The present invention provides a method for producing polymer particles, which comprises a step of subjecting the polymer particle group B1 to surface crosslinks.
　本発明の他の一側面は、アルコール及び水を含有する表面架橋剤溶液を用いて、目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した重合体粒子群Ｂ１に表面架橋を施す工程を備え、前記水に対する前記アルコールの体積比が０．２５～２．００である、重合体粒子の製造方法を提供する。 Another aspect of the present invention is the polymer particle group B1 that has passed through the sieve when the polymer particle group is classified by a sieve having a mesh size of 212 μm or less using a surface cross-linking agent solution containing alcohol and water. Provided is a method for producing polymer particles, which comprises a step of subjecting a surface crosslink and has a volume ratio of the alcohol to water of 0.25 to 2.00.
　これらの重合体粒子の製造方法によれば、吸水特性に優れた微粉として、加圧下における優れた吸水特性を有する重合体粒子を得ることが可能であり、微粉を有効に活用することができる。 According to the method for producing these polymer particles, it is possible to obtain polymer particles having excellent water absorption characteristics under pressure as fine powders having excellent water absorption characteristics, and the fine powders can be effectively utilized.
　本発明の一側面によれば、微粉を活用しつつ、加圧下における優れた吸水特性を有する吸水性樹脂粒子を得ることが可能な吸水性樹脂粒子の製造方法を提供することができる。本発明の他の一側面によれば、吸水特性に優れた微粉として、加圧下における優れた吸水特性を有する重合体粒子を得ることが可能な重合体粒子の製造方法を提供することができる。 According to one aspect of the present invention, it is possible to provide a method for producing water-absorbent resin particles capable of obtaining water-absorbent resin particles having excellent water-absorbing properties under pressure while utilizing fine powder. According to another aspect of the present invention, it is possible to provide a method for producing polymer particles capable of obtaining polymer particles having excellent water absorption characteristics under pressure as fine powder having excellent water absorption characteristics.
吸収性物品の一例を示す断面図である。It is sectional drawing which shows an example of an absorbent article. 加圧下における吸水特性の測定方法を説明するための図面である。It is a drawing for demonstrating the measuring method of the water absorption characteristic under pressure.
　以下、本発明の実施形態について詳細に説明する。但し、本発明は、以下の実施形態に限定されるものではなく、その要旨の範囲内で種々変形して実施することができる。 Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.
　本明細書において、「アクリル」及び「メタクリル」を合わせて「（メタ）アクリル」と表記する。「アクリレート」及び「メタクリレート」も同様に「（メタ）アクリレート」と表記する。本明細書に段階的に記載されている数値範囲において、ある段階の数値範囲の上限値又は下限値は、他の段階の数値範囲の上限値又は下限値と任意に組み合わせることができる。本明細書に記載されている数値範囲において、その数値範囲の上限値又は下限値は、［実施例］の欄に示されている値に置き換えてもよい。「水溶性」とは、２５℃において水に５質量％以上の溶解性を示すことをいう。本明細書に例示する材料は、１種単独で用いられてもよく、２種以上を組み合わせて用いられてもよい。組成物中の各成分の含有量は、組成物中に各成分に該当する物質が複数存在する場合、特に断らない限り、組成物中に存在する当該複数の物質の合計量を意味する。「生理食塩水」とは、０．９質量％塩化ナトリウム水溶液をいう。「室温」は、２５℃を意味する。本明細書において、粒子の集合体である粒子群を「粒子」と記載している場合もある。 In this specification, "acrylic" and "methacryl" are collectively referred to as "(meth) acrylic". Similarly, "acrylate" and "methacrylate" are also referred to as "(meth) acrylate". In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value of the numerical range of one step can be arbitrarily combined with the upper limit value or the lower limit value of the numerical range of another step. In the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the [Example] column. "Water-soluble" means that it exhibits a solubility in water of 5% by mass or more at 25 ° C. The materials exemplified in the present specification may be used alone or in combination of two or more. The content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified. "Saline" refers to a 0.9% by mass sodium chloride aqueous solution. "Room temperature" means 25 ° C. In the present specification, a particle group which is an aggregate of particles may be described as "particle".
　ＣＲＣは、Ｃｅｎｔｒｉｆｕｇｅ　Ｒｅｔｅｎｔｉｏｎ　Ｃａｐａｃｉｔｙ（遠心分離機保持容量）の略称である。ＣＲＣは、ＥＤＡＮＡ法（ＮＷＳＰ　２４１．０．Ｒ２（１５）、ｐａｇｅ．７６９～７７８）を参考に、後述する実施例に記載の方法によって測定できる。４．８３ｋＰａ（０．７ｐｓｉ）加圧下の吸収倍率（ＡＡＰ）は、後述する［実施例］の欄に記載の方法によって測定できる。ＣＲＣ、及び、４．８３ｋＰａ加圧下の吸収倍率としては、室温における測定値を用いることができる。 CRC is an abbreviation for Centrifuge Retention Capacity (centrifuge holding capacity). The CRC can be measured by the method described in Examples described later with reference to the EDANA method (NWSP 241.0.R2 (15), page.769-778). The absorption ratio (AAP) under pressurization of 4.83 kPa (0.7 psi) can be measured by the method described in the column of [Example] described later. As the CRC and the absorption ratio under pressurization of 4.83 kPa, the measured value at room temperature can be used.
　重合体粒子群の質量を基準とした各成分の使用量において重合体粒子群の質量（例えば、下記「１００質量部の重合体粒子群」等の表現）は、重合体粒子群の固形分量を意味している。固形分量は、下記式から算出できる。
　　固形分量＝重合体粒子群の質量×｛１－（乾燥減量［％］／１００）｝ In the amount of each component used based on the mass of the polymer particle group, the mass of the polymer particle group (for example, the expression such as "100 parts by mass of the polymer particle group" below) is the solid content of the polymer particle group. Means. The solid content can be calculated from the following formula.
Solid content = mass of polymer particle group x {1- (dry weight loss [%] / 100)}
　乾燥減量は、次の手順で測定できる。粒子２．０ｇをアルミニウムホイールケース（８号。恒量：Ｗ１［ｇ］）にとり、全体量Ｗ２［ｇ］を精秤する。内温を１０５℃に設定した熱風乾燥機（例えば、ＡＤＶＡＮＴＥＣ社製、型式：ＦＶ－３２０）で２時間乾燥させた後、デシケーター中で放冷し、乾燥後の全体量Ｗ３［ｇ］を測定する。そして、下記式から乾燥減量を算出する。
　　乾燥減量［質量％］＝〔｛（Ｗ２－Ｗ１）－（Ｗ３－Ｗ１）｝／（Ｗ２－Ｗ１）〕×１００ The dry weight loss can be measured by the following procedure. Take 2.0 g of particles in an aluminum wheel case (No. 8, constant amount: W1 [g]) and weigh the total amount W2 [g] precisely. After drying for 2 hours in a hot air dryer (for example, manufactured by ADVANTEC, model: FV-320) whose internal temperature is set to 105 ° C., the mixture is allowed to cool in a desiccator, and the total amount W3 [g] after drying is measured. To do. Then, the dry weight loss is calculated from the following formula.
Loss on drying [mass%] = [{(W2-W1)-(W3-W1)} / (W2-W1)] x 100
　本実施形態（後述の第１実施形態及び第２実施形態を包含する。以下同様）に係る吸水性樹脂粒子の製造方法は、目開き２１２μｍ以下の篩Ｓ１で重合体粒子群を分級した際に当該篩Ｓ１上に残存する重合体粒子群Ａ１に表面架橋を施して得られる重合体粒子群Ａ２と、目開き２１２μｍ以下の篩Ｓ２で重合体粒子群を分級した際に当該篩Ｓ２を通過した重合体粒子群Ｂ１に表面架橋を施して得られる重合体粒子群Ｂ２と、を混合することにより吸水性樹脂粒子（吸水性樹脂粒子群）を得る混合工程を備える。 The method for producing the water-absorbent resin particles according to the present embodiment (including the first embodiment and the second embodiment described later; the same applies hereinafter) is when the polymer particle group is classified by a sieve S1 having a mesh size of 212 μm or less. When the polymer particle group A2 obtained by surface cross-linking the polymer particle group A1 remaining on the sieve S1 and the polymer particle group A2 having a mesh size of 212 μm or less were used to classify the polymer particle group, the polymer particle group passed through the sieve S2. The present invention comprises a mixing step of obtaining water-absorbent resin particles (water-absorbent resin particle group) by mixing the polymer particle group B1 obtained by subjecting the polymer particle group B1 with a surface-crosslinked polymer particle group B2.
　本実施形態に係る吸水性樹脂粒子の製造方法によれば、微粉（重合体粒子群Ｂ１）を活用しつつ、加圧下における優れた吸水特性（例えば、４．８３ｋＰａ加圧下の吸収倍率（ＡＡＰ））を有する吸水性樹脂粒子を得ることができる。本実施形態に係る吸水性樹脂粒子の製造方法によれば、表面架橋前に分級することなく表面架橋後に分級して得られた複数の重合体粒子群を混合した場合と比較して、加圧下における優れた吸水特性を得ることができる。本実施形態に係る吸水性樹脂粒子の製造方法によれば、加圧下における優れた吸水特性に加えて優れたＣＲＣを有する吸水性樹脂粒子を得ることもできる。 According to the method for producing water-absorbent resin particles according to the present embodiment, excellent water absorption characteristics under pressure (for example, absorption ratio (AAP) under pressure of 4.83 kPa) while utilizing fine powder (polymer particle group B1). ) Can be obtained. According to the method for producing water-absorbent resin particles according to the present embodiment, as compared with the case where a plurality of polymer particle groups obtained by classifying after surface cross-linking without classifying before surface cross-linking are mixed, under pressure. Excellent water absorption characteristics can be obtained. According to the method for producing water-absorbent resin particles according to the present embodiment, it is possible to obtain water-absorbent resin particles having excellent CRC in addition to excellent water-absorbing characteristics under pressure.
　このような吸水性樹脂粒子を得ることが可能な要因は、例えば、下記のとおりであると推測される。すなわち、重合体粒子群Ａ１と重合体粒子群Ｂ１とで好適な表面架橋の条件が異なる場合、表面架橋前に分級することなく表面架橋を行うと、これらの重合体粒子群のいずれかに対して好適な表面架橋が施せない。一方、本実施形態に係る吸水性樹脂粒子の製造方法では、重合体粒子群Ａ１と重合体粒子群Ｂ１とで好適な表面架橋の条件が異なる場合であっても、分級後に表面架橋を行うことにより、表面架橋の条件を互いに異ならせることで、重合体粒子群Ａ１及び重合体粒子群Ｂ１のそれぞれに好適な表面架橋を施すことができる。好適な表面架橋を施して得られる重合体粒子群Ａ２と重合体粒子群Ｂ２とを混合することにより、例えば、吸水性樹脂粒子の全体において均等な表面架橋状態を達成できる。例えば、重合体粒子群Ｂ１の表面架橋の条件を調整することで重合体粒子群Ｂ１の表面架橋剤の吸収速度を変更した上で表面架橋を施した重合体粒子群Ｂ２と、重合体粒子群Ａ２と、を混合することにより、吸水性樹脂粒子の全体において均等な表面架橋状態を達成できる。但し、優れた吸水特性を得ることが可能な要因は上述の内容に限定されない。なお、重合体粒子群Ａ１と重合体粒子群Ｂ１とで好適な表面架橋の条件が互いに同等である場合には、分級後の表面架橋において互いに同等の条件を用いてよい。 It is presumed that the factors that make it possible to obtain such water-absorbent resin particles are as follows, for example. That is, when the suitable surface cross-linking conditions are different between the polymer particle group A1 and the polymer particle group B1, if the surface cross-linking is performed without classifying before the surface cross-linking, the surface cross-linking is performed on any of these polymer particle groups. Therefore, suitable surface cross-linking cannot be performed. On the other hand, in the method for producing water-absorbent resin particles according to the present embodiment, even if the suitable surface cross-linking conditions are different between the polymer particle group A1 and the polymer particle group B1, surface cross-linking is performed after classification. Therefore, by making the conditions of surface cross-linking different from each other, suitable surface cross-linking can be performed on each of the polymer particle group A1 and the polymer particle group B1. By mixing the polymer particle group A2 and the polymer particle group B2 obtained by performing suitable surface cross-linking, for example, a uniform surface cross-linking state can be achieved in the entire water-absorbent resin particles. For example, the polymer particle group B2 and the polymer particle group which have been subjected to surface cross-linking after changing the absorption rate of the surface cross-linking agent of the polymer particle group B1 by adjusting the surface cross-linking condition of the polymer particle group B1. By mixing A2 and A2, a uniform surface cross-linked state can be achieved over the entire water-absorbent resin particles. However, the factors capable of obtaining excellent water absorption characteristics are not limited to the above-mentioned contents. When the suitable surface cross-linking conditions for the polymer particle group A1 and the polymer particle group B1 are the same, the same conditions may be used for the surface cross-linking after classification.
　混合工程においては、１００質量部の重合体粒子群Ａ２と、下記範囲の重合体粒子群Ｂ２と、を混合することが好ましい。重合体粒子群Ｂ２の混合量は、加圧下における優れた吸水特性を得やすい観点から、５０質量部未満が好ましく、４５質量部以下がより好ましく、４０質量部以下が更に好ましく、３５質量部以下が特に好ましく、３３質量部以下が極めて好ましく、３０質量部以下が非常に好ましく、２５質量部以下がより一層好ましく、２０質量部以下が更に好ましく、１５質量部以下が特に好ましく、１２質量部以下が極めて好ましい。重合体粒子群Ｂ２の混合量は、微粉の活用効率を高める観点から、１質量部以上が好ましく、３質量部以上がより好ましく、５質量部以上が更に好ましく、７質量部以上が特に好ましく、９質量部以上が極めて好ましく、１０質量部以上が非常に好ましく、１１質量部以上がより一層好ましい。これらの観点から、重合体粒子群Ｂ２の混合量は、１質量部以上５０質量部未満が好ましく、５～３０質量部がより好ましく、１０～２０質量部が更に好ましい。 In the mixing step, it is preferable to mix 100 parts by mass of the polymer particle group A2 and the polymer particle group B2 in the following range. The mixing amount of the polymer particle group B2 is preferably less than 50 parts by mass, more preferably 45 parts by mass or less, further preferably 40 parts by mass or less, and 35 parts by mass or less from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is particularly preferable, 33 parts by mass or less is extremely preferable, 30 parts by mass or less is very preferable, 25 parts by mass or less is even more preferable, 20 parts by mass or less is further preferable, 15 parts by mass or less is particularly preferable, and 12 parts by mass or less. Is extremely preferable. The mixing amount of the polymer particle group B2 is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, from the viewpoint of enhancing the utilization efficiency of the fine powder. 9 parts by mass or more is extremely preferable, 10 parts by mass or more is very preferable, and 11 parts by mass or more is even more preferable. From these viewpoints, the mixing amount of the polymer particle group B2 is preferably 1 part by mass or more and less than 50 parts by mass, more preferably 5 to 30 parts by mass, and further preferably 10 to 20 parts by mass.
　重合体粒子群Ａ２のＣＲＣは、下記の範囲が好ましい。ＣＲＣは、２０ｇ／ｇ以上が好ましく、２５ｇ／ｇ以上がより好ましく、２７ｇ／ｇ以上が更に好ましく、２８ｇ／ｇ以上が特に好ましく、２９ｇ／ｇ以上が極めて好ましく、３０ｇ／ｇ以上が非常に好ましく、３１ｇ／ｇ以上がより一層好ましく、３３ｇ／ｇ以上が更に好ましく、３５ｇ／ｇ以上が特に好ましく、３６ｇ／ｇ以上が極めて好ましい。ＣＲＣは、６０ｇ／ｇ以下が好ましく、５５ｇ／ｇ以下がより好ましく、５０ｇ／ｇ以下が更に好ましく、４５ｇ／ｇ以下が特に好ましく、４０ｇ／ｇ以下が極めて好ましく、３８ｇ／ｇ以下が非常に好ましい。これらの観点から、ＣＲＣは、２０～６０ｇ／ｇが好ましく、２０～５０ｇ／ｇがより好ましく、２５～４０ｇ／ｇが更に好ましい。 The CRC of the polymer particle group A2 is preferably in the following range. The CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 27 g / g or more, particularly preferably 28 g / g or more, extremely preferably 29 g / g or more, and very preferably 30 g / g or more. , 31 g / g or more is even more preferable, 33 g / g or more is further preferable, 35 g / g or more is particularly preferable, and 36 g / g or more is extremely preferable. The CRC is preferably 60 g / g or less, more preferably 55 g / g or less, further preferably 50 g / g or less, particularly preferably 45 g / g or less, extremely preferably 40 g / g or less, and very preferably 38 g / g or less. .. From these viewpoints, the CRC is preferably 20 to 60 g / g, more preferably 20 to 50 g / g, and even more preferably 25 to 40 g / g.
　重合体粒子群Ａ２の４．８３ｋＰａ加圧下の吸収倍率（ＡＡＰ）は、６．０ｇ／ｇ以上が好ましく、６．５ｇ／ｇ以上がより好ましく、７．０ｇ／ｇ以上が更に好ましく、７．５ｇ／ｇ以上が特に好ましく、８．０ｇ／ｇ以上が極めて好ましく、８．５ｇ／ｇ以上が非常に好ましく、９．０ｇ／ｇ以上がより一層好ましく、１０．０ｇ／ｇ以上が更に好ましく、１１．０ｇ／ｇ以上が特に好ましく、１２．０ｇ／ｇ以上が極めて好ましく、１４．０ｇ／ｇ以上が非常に好ましい。重合体粒子群Ａ２の４．８３ｋＰａ加圧下の吸収倍率（ＡＡＰ）の上限は、例えば、４０．０ｇ／ｇ以下、３５．０ｇ／ｇ以下、３０．０ｇ／ｇ以下、２５．０ｇ／ｇ以下、又は、２０．０ｇ／ｇ以下であってよい。 The absorption ratio (AAP) of the polymer particle group A2 under pressurization of 4.83 kPa is preferably 6.0 g / g or more, more preferably 6.5 g / g or more, further preferably 7.0 g / g or more, and 7. 5 g / g or more is particularly preferable, 8.0 g / g or more is extremely preferable, 8.5 g / g or more is very preferable, 9.0 g / g or more is further preferable, 10.0 g / g or more is further preferable, and 10.0 g / g or more is further preferable. 11.0 g / g or more is particularly preferable, 12.0 g / g or more is extremely preferable, and 14.0 g / g or more is very preferable. The upper limit of the absorption ratio (AAP) of the polymer particle group A2 under pressure of 4.83 kPa is, for example, 40.0 g / g or less, 35.0 g / g or less, 30.0 g / g or less, 25.0 g / g or less. Or, it may be 20.0 g / g or less.
　重合体粒子群Ｂ２のＣＲＣは、下記の範囲が好ましい。ＣＲＣは、２０ｇ／ｇ以上が好ましく、２５ｇ／ｇ以上がより好ましく、３０ｇ／ｇ以上が更に好ましく、３１ｇ／ｇ以上が特に好ましく、３２ｇ／ｇ以上が極めて好ましく、３３ｇ／ｇ以上が非常に好ましく、３４ｇ／ｇ以上がより一層好ましい。ＣＲＣは、６０ｇ／ｇ以下が好ましく、５５ｇ／ｇ以下がより好ましく、５０ｇ／ｇ以下が更に好ましく、４５ｇ／ｇ以下が特に好ましく、４０ｇ／ｇ以下が極めて好ましく、３５ｇ／ｇ以下が非常に好ましい。これらの観点から、ＣＲＣは、２０～６０ｇ／ｇが好ましく、２０～５０ｇ／ｇがより好ましく、３０～４０ｇ／ｇが更に好ましい。 The CRC of the polymer particle group B2 is preferably in the following range. The CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 30 g / g or more, particularly preferably 31 g / g or more, extremely preferably 32 g / g or more, and very preferably 33 g / g or more. , 34 g / g or more is even more preferable. The CRC is preferably 60 g / g or less, more preferably 55 g / g or less, further preferably 50 g / g or less, particularly preferably 45 g / g or less, extremely preferably 40 g / g or less, and very preferably 35 g / g or less. .. From these viewpoints, the CRC is preferably 20 to 60 g / g, more preferably 20 to 50 g / g, and even more preferably 30 to 40 g / g.
　重合体粒子群Ｂ２の４．８３ｋＰａ加圧下の吸収倍率（ＡＡＰ）は、８．０ｇ／ｇ以上が好ましく、９．０ｇ／ｇ以上がより好ましく、１０．０ｇ／ｇ以上が更に好ましく、１２．０ｇ／ｇ以上が特に好ましく、１５．０ｇ／ｇ以上が極めて好ましく、１８．０ｇ／ｇ以上が非常に好ましく、１９．０ｇ／ｇ以上がより一層好ましい。重合体粒子群Ｂ２の４．８３ｋＰａ加圧下の吸収倍率（ＡＡＰ）の上限は、例えば、４０．０ｇ／ｇ以下、３５．０ｇ／ｇ以下、３０．０ｇ／ｇ以下、２５．０ｇ／ｇ以下、又は、２０．０ｇ／ｇ以下であってよい。 The absorption ratio (AAP) of the polymer particle group B2 under pressure of 4.83 kPa is preferably 8.0 g / g or more, more preferably 9.0 g / g or more, further preferably 10.0 g / g or more, and 12. 0 g / g or more is particularly preferable, 15.0 g / g or more is extremely preferable, 18.0 g / g or more is very preferable, and 19.0 g / g or more is even more preferable. The upper limit of the absorption ratio (AAP) of the polymer particle group B2 under pressure of 4.83 kPa is, for example, 40.0 g / g or less, 35.0 g / g or less, 30.0 g / g or less, 25.0 g / g or less. Or, it may be 20.0 g / g or less.
　後述の分級工程において三つ以上の重合体粒子群に分級された場合、分級されたうちの少なくとも二つ以上の重合体粒子群に対して表面架橋を施して互いに混合すればよい。この場合、分級されたうちの全てを互いに混合してよく、分級された一部の重合体粒子群を混合しなくてもよい。 When classified into three or more polymer particle groups in the classification step described later, at least two or more polymer particle groups among the classified groups may be surface-crosslinked and mixed with each other. In this case, all of the classifieds may be mixed with each other, and some of the classified polymer particle groups may not be mixed.
　混合工程において重合体粒子群Ａ２と重合体粒子群Ｂ２とを混合する際の温度は、５℃以上１００℃未満、５～９０℃、又は、５～８０℃であってよい。 The temperature at which the polymer particle group A2 and the polymer particle group B2 are mixed in the mixing step may be 5 ° C. or higher and lower than 100 ° C., 5 to 90 ° C., or 5 to 80 ° C.
　重合体粒子群Ａ２は、目開き２１２μｍ以下の篩Ｓ１で重合体粒子群を分級した際に当該篩Ｓ１上に残存する重合体粒子群Ａ１に表面架橋を施して得られる重合体粒子群である。重合体粒子群Ｂ２は、目開き２１２μｍ以下の篩Ｓ２で重合体粒子群を分級した際に当該篩Ｓ２を通過した重合体粒子群Ｂ１に表面架橋を施して得られる重合体粒子群である。篩Ｓ１又は篩Ｓ２を用いた分級の対象である重合体粒子群は、粗大粒子を取り除く観点から、目開き８５０μｍ以上の篩で重合体粒子群を分級した際に当該篩を通過した重合体粒子群であってもよい。篩Ｓ１又は篩Ｓ２を用いた分級の対象である重合体粒子群は、極めて小さい微粉を取り除く観点から、目開き４５μｍ以下の篩で重合体粒子群を分級した際に当該篩上に残存する重合体粒子群であってもよい。 The polymer particle group A2 is a polymer particle group obtained by subjecting the polymer particle group A1 remaining on the sieve S1 to surface cross-linking when the polymer particle group is classified by a sieve S1 having a mesh size of 212 μm or less. .. The polymer particle group B2 is a polymer particle group obtained by subjecting the polymer particle group B1 that has passed through the sieve S2 to surface cross-linking when the polymer particle group is classified by a sieve S2 having a mesh size of 212 μm or less. The polymer particle group to be classified using the sieve S1 or the sieve S2 is a polymer particle that has passed through the sieve when the polymer particle group is classified with a sieve having an opening of 850 μm or more from the viewpoint of removing coarse particles. It may be a group. The polymer particle group to be classified using the sieve S1 or the sieve S2 has a weight remaining on the sieve when the polymer particle group is classified with a sieve having an opening of 45 μm or less from the viewpoint of removing extremely small fine powder. It may be a coalesced particle group.
　重合体粒子群Ａ１及び重合体粒子群Ｂ１は、互いに同一の重合体粒子群を分級して得られてよく、互いに異なる重合体粒子群を分級して得られてもよい。互いに同一の重合体粒子群を分級する場合、篩Ｓ１及び篩Ｓ２は互いに同一の篩（同一物）である。互いに異なる重合体粒子群を分級する場合、篩Ｓ１及び篩Ｓ２は、互いに異なる篩であってよく、互いに同一の篩であってもよい。 The polymer particle group A1 and the polymer particle group B1 may be obtained by classifying the same polymer particle group from each other, or may be obtained by classifying different polymer particle groups from each other. When classifying polymer particle groups that are the same as each other, the sieve S1 and the sieve S2 are the same sieve (the same product). When classifying polymer particle groups different from each other, the sieve S1 and the sieve S2 may be different sieves or the same sieves.
　第１実施形態に係る吸水性樹脂粒子の製造方法は、混合工程の前に、重合体粒子群Ｃを篩Ｓ１（篩Ｓ１及び篩Ｓ２は互いに同一の篩である）で分級することにより重合体粒子群Ａ１及び重合体粒子群Ｂ１を得る分級工程Ｉを備えてよい。第２実施形態に係る吸水性樹脂粒子の製造方法は、混合工程の前に、重合体粒子群Ｄ１を篩Ｓ１で分級することにより重合体粒子群Ａ１を得る分級工程ＩＩａと、重合体粒子群Ｄ１とは異なる重合体粒子群Ｄ２を篩Ｓ２で分級することにより重合体粒子群Ｂ１を得る分級工程ＩＩｂと、を備えてよい。第２実施形態に係る吸水性樹脂粒子の製造方法において、篩Ｓ１及び篩Ｓ２の目開きは、互いに同一であってよく、互いに異なっていてもよい。第２実施形態に係る吸水性樹脂粒子の製造方法において、互いに異なる篩である篩Ｓ１及び篩Ｓ２で分級してよい（篩Ｓ２は、篩Ｓ１とは異なる篩であってよい）。また、第２実施形態に係る吸水性樹脂粒子の製造方法において、互いに同一の篩（同一物）である篩Ｓ１及び篩Ｓ２を用いて、分級工程ＩＩａ及び分級工程ＩＩｂのうちの一方を行った後に分級工程ＩＩａ及び分級工程ＩＩｂのうちの他方を行ってもよい（すなわち、同一の篩で繰り返し分級を行ってよい）。 In the method for producing water-absorbent resin particles according to the first embodiment, the polymer particle group C is classified by a sieve S1 (the sieve S1 and the sieve S2 are the same sieves) before the mixing step to classify the polymer. The classification step I for obtaining the particle group A1 and the polymer particle group B1 may be provided. The method for producing the water-absorbent resin particles according to the second embodiment includes a classification step IIa for obtaining the polymer particle group A1 by classifying the polymer particle group D1 with a sieve S1 before the mixing step, and a polymer particle group. A classification step IIb for obtaining the polymer particle group B1 by classifying the polymer particle group D2 different from D1 with a sieve S2 may be provided. In the method for producing water-absorbent resin particles according to the second embodiment, the meshes of the sieve S1 and the sieve S2 may be the same or different from each other. In the method for producing water-absorbent resin particles according to the second embodiment, the sieves S1 and S2, which are different sieves from each other, may be classified (the sieve S2 may be a sieve different from the sieve S1). Further, in the method for producing water-absorbent resin particles according to the second embodiment, one of the classification step IIa and the classification step IIb was performed using the sieves S1 and S2 which are the same sieves (same thing) as each other. The other of the classification step IIa and the classification step IIb may be performed later (that is, the classification may be repeated with the same sieve).
　第２実施形態に係る吸水性樹脂粒子の製造方法における重合体粒子群Ｄ１及び重合体粒子群Ｄ２は、互いに異なる重合体粒子群である。重合体粒子群Ｄ１と重合体粒子群Ｄ２は、同一条件で製造された重合体粒子群であってもよい。重合体粒子群Ｄ１及び重合体粒子群Ｄ２のうちの一方の重合体粒子群は、重合体粒子群Ｄ１及び重合体粒子群Ｄ２の他方に各種処理を施して得られる重合体粒子群であってよい。また、重合体粒子群Ｄ１及び重合体粒子群Ｄ２のうちの一方の重合体粒子群は、重合体粒子群Ｄ１及び重合体粒子群Ｄ２のうちの他方の重合体粒子群の各種処理前又は処理後の重合体粒子群とは異なる重合体粒子群であってよい。 The polymer particle group D1 and the polymer particle group D2 in the method for producing water-absorbent resin particles according to the second embodiment are different polymer particle groups from each other. The polymer particle group D1 and the polymer particle group D2 may be a polymer particle group produced under the same conditions. The polymer particle group of one of the polymer particle group D1 and the polymer particle group D2 is a polymer particle group obtained by subjecting the other of the polymer particle group D1 and the polymer particle group D2 to various treatments. Good. Further, the polymer particle group of one of the polymer particle group D1 and the polymer particle group D2 is before or after various treatments of the other polymer particle group of the polymer particle group D1 and the polymer particle group D2. It may be a polymer particle group different from the later polymer particle group.
　上述の各分級工程では、分級対象の重合体粒子群を複数の重合体粒子群に分級できればよく、篩Ｓ１又は篩Ｓ２で二つの重合体粒子群に分級してよく、篩Ｓ１又は篩Ｓ２を含む複数の篩で三つ以上の重合体粒子群に分級してもよい。例えば、第１実施形態に係る吸水性樹脂粒子の製造方法における分級工程Ｉでは、重合体粒子群Ｃを篩Ｓ１で重合体粒子群Ａ１及び重合体粒子群Ｂ１の二つに分級してよい。第２実施形態に係る吸水性樹脂粒子の製造方法における分級工程ＩＩａでは、篩Ｓ１で重合体粒子群Ｄ１を二つに分級してよく、篩Ｓ１を含む複数の篩で重合体粒子群Ｄ１を三つ以上に分級してよい。第２実施形態に係る吸水性樹脂粒子の製造方法における分級工程ＩＩｂでは、篩Ｓ２で重合体粒子群Ｄ２を二つに分級してよく、篩Ｓ２を含む複数の篩で重合体粒子群Ｄ２を三つ以上に分級してよい。 In each of the above-mentioned classification steps, it is sufficient that the polymer particle group to be classified can be classified into a plurality of polymer particle groups, and the sieve S1 or the sieve S2 may be used to classify the polymer particle group into two polymer particle groups. It may be classified into three or more polymer particle groups by a plurality of sieves containing. For example, in the classification step I in the method for producing water-absorbent resin particles according to the first embodiment, the polymer particle group C may be classified into the polymer particle group A1 and the polymer particle group B1 by a sieve S1. In the classification step IIa in the method for producing water-absorbent resin particles according to the second embodiment, the polymer particle group D1 may be classified into two by a sieve S1, and the polymer particle group D1 may be classified into two by a plurality of sieves including the sieve S1. It may be classified into three or more. In the classification step IIb in the method for producing water-absorbent resin particles according to the second embodiment, the polymer particle group D2 may be classified into two by a sieve S2, and the polymer particle group D2 may be classified into two by a plurality of sieves including the sieve S2. It may be classified into three or more.
　目開き２１２μｍ以下の篩（篩Ｓ１及び篩Ｓ２）としては、ＪＩＳ　Ｚ８８０１－１に規定された目開き２１２μｍ以下の篩を用いてよい。篩の目開きは、１８０μｍ以下であってよい。篩の目開きは、４５μｍ以上、７５μｍ以上、９０μｍ以上、１０６μｍ以上、１２５μｍ以上、１５０μｍ以上、又は、１８０μｍ以上であってよい。 As the sieve having a mesh size of 212 μm or less (sieve S1 and sieve S2), a sieve having a mesh size of 212 μm or less specified in JIS Z8801-1 may be used. The mesh size of the sieve may be 180 μm or less. The mesh size of the sieve may be 45 μm or more, 75 μm or more, 90 μm or more, 106 μm or more, 125 μm or more, 150 μm or more, or 180 μm or more.
　篩Ｓ１又は篩Ｓ２を用いた分級の対象である重合体粒子群のＣＲＣは、下記の範囲が好ましい。ＣＲＣは、吸収性物品に用いた際に吸収量を高めやすい観点から、２０ｇ／ｇ以上が好ましく、２５ｇ／ｇ以上がより好ましく、３０ｇ／ｇ以上が更に好ましく、３５ｇ／ｇ以上が特に好ましく、３９ｇ／ｇ以上が極めて好ましい。ＣＲＣは、加圧下における優れた吸水特性を得やすい観点から、８０ｇ／ｇ以下が好ましく、７０ｇ／ｇ以下が好ましく、６０ｇ／ｇ以下が更に好ましく、５５ｇ／ｇ以下が特に好ましく、５０ｇ／ｇ以下が極めて好ましく、４５ｇ／ｇ以下が非常に好ましく、４０ｇ／ｇ以下がより一層好ましい。これらの観点から、ＣＲＣは、２０～８０ｇ／ｇが好ましく、２５～６０ｇ／ｇがより好ましく、３０～５０ｇ／ｇが更に好ましい。 The CRC of the polymer particle group to be classified using the sieve S1 or the sieve S2 is preferably in the following range. The CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 30 g / g or more, particularly preferably 35 g / g or more, from the viewpoint of easily increasing the absorption amount when used in an absorbent article. 39 g / g or more is extremely preferable. The CRC is preferably 80 g / g or less, preferably 70 g / g or less, further preferably 60 g / g or less, particularly preferably 55 g / g or less, and particularly preferably 50 g / g or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is extremely preferable, 45 g / g or less is very preferable, and 40 g / g or less is even more preferable. From these viewpoints, the CRC is preferably 20 to 80 g / g, more preferably 25 to 60 g / g, and even more preferably 30 to 50 g / g.
　篩Ｓ１又は篩Ｓ２を用いた分級の対象である重合体粒子群の中位粒子径は、下記の範囲が好ましい。中位粒子径は、吸水性樹脂粒子において加圧下における優れた吸水特性を得やすい観点、及び、ゲルブロッキングを回避することにより、吸収性物品に用いた際に吸収性能を良好に保ちやすい観点から、２００μｍ以上が好ましく、２３０μｍ以上がより好ましく、２５０μｍ以上が更に好ましい。中位粒子径は、吸収性物品に用いた際の触感を柔らかく保ちやすい観点から、６００μｍ以下が好ましく、５５０μｍ以下がより好ましく、５００μｍ以下が更に好ましく、４５０μｍ以下が特に好ましく、４００μｍ以下が極めて好ましい。これらの観点から、中位粒子径は、２００～６００μｍが好ましく、２３０～５００μｍがより好ましく、２５０～４００μｍが更に好ましい。中位粒子径は、吸水性樹脂粒子において加圧下における更に優れた吸水特性を得やすい観点から、２６０μｍ以上が好ましく、２８０μｍ以上がより好ましく、３００μｍ以上が更に好ましく、３３０μｍ以上が特に好ましく、３５０μｍ以上が極めて好ましい。中位粒子径は、吸水性樹脂粒子において更に優れたＣＲＣを得やすい観点から、３５０μｍ以下が好ましく、３２０μｍ以下がより好ましく、３００μｍ以下が更に好ましく、２８０μｍ以下が特に好ましく、２６０μｍ以下が極めて好ましい。中位粒子径は、後述する［実施例］の欄に記載の方法によって測定できる。中位粒子径としては、質量基準の粒子径であり、室温における測定値を用いることができる。 The medium particle size of the polymer particle group to be classified using the sieve S1 or the sieve S2 is preferably in the following range. The medium particle size is from the viewpoint that it is easy to obtain excellent water absorption characteristics under pressure in the water-absorbent resin particles, and from the viewpoint that it is easy to maintain good absorption performance when used in an absorbent article by avoiding gel blocking. , 200 μm or more is preferable, 230 μm or more is more preferable, and 250 μm or more is further preferable. The medium particle size is preferably 600 μm or less, more preferably 550 μm or less, further preferably 500 μm or less, particularly preferably 450 μm or less, and extremely preferably 400 μm or less, from the viewpoint of easily keeping the tactile sensation soft when used in an absorbent article. .. From these viewpoints, the medium particle size is preferably 200 to 600 μm, more preferably 230 to 500 μm, and even more preferably 250 to 400 μm. The medium particle size is preferably 260 μm or more, more preferably 280 μm or more, further preferably 300 μm or more, particularly preferably 330 μm or more, and particularly preferably 350 μm or more, from the viewpoint of easily obtaining more excellent water absorption characteristics under pressure in the water-absorbent resin particles. Is extremely preferable. The medium particle size is preferably 350 μm or less, more preferably 320 μm or less, further preferably 300 μm or less, particularly preferably 280 μm or less, and extremely preferably 260 μm or less, from the viewpoint of easily obtaining a more excellent CRC in the water-absorbent resin particles. The medium particle size can be measured by the method described in the [Example] column described later. The medium particle size is a mass-based particle size, and a measured value at room temperature can be used.
　本実施形態に係る吸水性樹脂粒子の製造方法は、混合工程の前、かつ、分級工程の後に、重合体粒子群Ａ１に表面架橋を施して重合体粒子群Ａ２を得る表面架橋工程Ｉと、重合体粒子群Ｂ１に表面架橋を施して重合体粒子群Ｂ２を得る表面架橋工程ＩＩと、を備えてよい。表面架橋工程Ｉ及び表面架橋工程ＩＩにおける表面架橋の条件は、互いに同一であってよく、互いに異なってもよい。 The method for producing the water-absorbent resin particles according to the present embodiment includes a surface cross-linking step I in which the polymer particle group A1 is surface-crosslinked to obtain the polymer particle group A2 before the mixing step and after the classification step. A surface cross-linking step II in which the polymer particle group B1 is surface-crosslinked to obtain the polymer particle group B2 may be provided. The conditions for surface cross-linking in the surface cross-linking step I and the surface cross-linking step II may be the same as each other or may be different from each other.
　粒径が小さいほど重合体粒子群の総比表面積が大きいことから、表面架橋工程ＩＩにおける表面架橋剤の使用量は、加圧下における優れた吸水特性を得やすい観点から、表面架橋工程Ｉにおける表面架橋剤の使用量よりも多くてよい。 Since the smaller the particle size, the larger the total specific surface area of the polymer particle group, the amount of the surface cross-linking agent used in the surface cross-linking step II is the surface in the surface cross-linking step I from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. It may be larger than the amount of the cross-linking agent used.
　また、表面架橋工程ＩＩにおける表面架橋の条件は、加圧下における優れた吸水特性を得やすい観点から、表面架橋工程Ｉにおける表面架橋の条件と比較して、重合体粒子群における粒子の内部に対する表面架橋剤の吸収速度が遅い条件であることが好ましい。微粉である重合体粒子群Ｂ１は重合体粒子群Ａ１と比較して表面架橋剤の吸収速度が速い傾向があるものの、重合体粒子群Ｂ１において粒子の内部に対する表面架橋剤の吸収速度を低下させることによって粒子の表面において表面架橋剤が均一に拡散し、表面全体において均一な架橋を達成できると推測される。例えば、表面架橋工程ＩＩにおける表面架橋剤の混合温度は、粒子の内部に対する表面架橋剤の吸収速度を低下させやすい観点から、表面架橋工程Ｉにおける表面架橋剤の混合温度よりも低くてよい（混合温度の詳細については後述する）。表面架橋工程ＩＩにおけるアルコールの使用量は、粒子の内部に吸収されづらいアルコールの使用量が増えることにより、粒子の内部に対する表面架橋剤の吸収速度を低下させやすい観点から、表面架橋工程Ｉにおけるアルコールの使用量よりも多くてよい（使用量としては、例えば、後述の「水に対するアルコールの体積比」又は「表面架橋剤溶液におけるアルコールの使用量」を用いることができる）。 Further, the surface cross-linking conditions in the surface cross-linking step II are compared with the surface cross-linking conditions in the surface cross-linking step I from the viewpoint of easily obtaining excellent water absorption characteristics under pressure, and the surface of the particles in the polymer particle group with respect to the inside It is preferable that the absorption rate of the cross-linking agent is slow. The polymer particle group B1 which is a fine powder tends to have a higher absorption rate of the surface cross-linking agent than the polymer particle group A1, but in the polymer particle group B1, the absorption rate of the surface cross-linking agent to the inside of the particles is lowered. It is presumed that this allows the surface cross-linking agent to diffuse uniformly on the surface of the particles, and uniform cross-linking can be achieved over the entire surface. For example, the mixing temperature of the surface cross-linking agent in the surface cross-linking step II may be lower than the mixing temperature of the surface cross-linking agent in the surface cross-linking step I from the viewpoint of easily reducing the absorption rate of the surface cross-linking agent into the inside of the particles (mixing). Details of the temperature will be described later). The amount of alcohol used in the surface cross-linking step II is such that the amount of alcohol that is difficult to be absorbed inside the particles increases, so that the absorption rate of the surface cross-linking agent into the inside of the particles tends to decrease. (As the amount used, for example, "volume ratio of alcohol to water" or "amount of alcohol used in the surface cross-linking agent solution" described later can be used).
　表面架橋工程では、表面架橋を行うための表面架橋剤を用いて、重合体粒子群に表面架橋を施すことができる。表面架橋剤としては、例えば、エチレン性不飽和単量体由来の官能基との反応性を有する官能基（反応性官能基。例えば水酸基）を２個以上含有する化合物を用いることができる。表面架橋剤としては、１，４－ブタンジオール、ジエチレングリコール、トリエチレングリコール、トリメチロールプロパン、グリセリン、ポリオキシエチレングリコール、ポリオキシプロピレングリコール、ポリグリセリン等のポリオール類；（ポリ）エチレングリコールジグリシジルエーテル、（ポリ）グリセリンジグリシジルエーテル、（ポリ）グリセリントリグリシジルエーテル、（ポリ）プロピレングリコールポリグリシジルエーテル、（ポリ）グリセロールポリグリシジルエーテル等のポリグリシジル化合物；エピクロルヒドリン、エピブロムヒドリン、α－メチルエピクロルヒドリン等のハロエポキシ化合物；２，４－トリレンジイソシアネート、ヘキサメチレンジイソシアネート等のイソシアネート化合物等の反応性官能基を２個以上有する化合物；３－メチル－３－オキセタンメタノール、３－エチル－３－オキセタンメタノール、３－ブチル－３－オキセタンメタノール、３－メチル－３－オキセタンエタノール、３－エチル－３－オキセタンエタノール、３－ブチル－３－オキセタンエタノール等のオキセタン化合物；１，２－エチレンビスオキサゾリン等のオキサゾリン化合物；エチレンカーボネート、プロピレンカーボネート、４，５－ジメチル－１，３－ジオキソラン－２－オン、４，４－ジメチル－１，３－ジオキソラン－２－オン、４－エチル－１，３－ジオキソラン－２－オン、４－ヒドロキシメチル－１，３－ジオキソラン－２－オン、１，３－ジオキサン－２－オン、４－メチル－１，３－ジオキサン－２－オン、４，６－ジメチル－１，３－ジオキサン－２－オン、１，３－ジオキソパン－２－オン等のカーボネート化合物（例えばアルキレンカーボネート）；ビス［Ｎ，Ｎ－ジ（β－ヒドロキシエチル）］アジプアミド等のヒドロキシアルキルアミド化合物などが挙げられる。表面架橋剤は、１種単独で用いられてもよく、２種以上を組み合わせて用いられてもよい。表面架橋剤は、加圧下における優れた吸水特性を得やすい観点から、カーボネート化合物を含むことが好ましく、アルキレンカーボネートを含むことがより好ましく、エチレンカーボネートを含むことが更に好ましい。 In the surface cross-linking step, the polymer particle group can be surface-crosslinked using a surface cross-linking agent for performing surface cross-linking. As the surface cross-linking agent, for example, a compound containing two or more functional groups (reactive functional groups, for example, hydroxyl groups) having reactivity with a functional group derived from an ethylenically unsaturated monomer can be used. Examples of the surface cross-linking agent include polyols such as 1,4-butanediol, diethylene glycol, triethylene glycol, trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, and polyglycerin; (poly) ethylene glycol diglycidyl ether. , (Poly) glycerin diglycidyl ether, (poly) glycerin triglycidyl ether, (poly) propylene glycol polyglycidyl ether, (poly) glycerol polyglycidyl ether and other polyglycidyl compounds; Haloepoxy compounds such as; compounds having two or more reactive functional groups such as isocyanate compounds such as 2,4-tolylene diisocyanate and hexamethylene diisocyanate; 3-methyl-3-oxetanemethanol, 3-ethyl-3-oxetanemethanol , 3-butyl-3-oxetanemethanol, 3-methyl-3-oxetaneethanol, 3-ethyl-3-oxetaneethanol, 3-butyl-3-oxetaneethanol and other oxetane compounds; Oxazoline compounds; ethylene carbonate, propylene carbonate, 4,5-dimethyl-1,3-dioxolan-2-one, 4,4-dimethyl-1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan -2-one, 4-hydroxymethyl-1,3-dioxolan-2-one, 1,3-dioxane-2-one, 4-methyl-1,3-dioxane-2-one, 4,6-dimethyl- Carbonate compounds such as 1,3-dioxane-2-one and 1,3-dioxopan-2-one (for example, alkylene carbonate); hydroxyalkylamide compounds such as bis [N, N-di (β-hydroxyethyl)] adipamide And so on. The surface cross-linking agent may be used alone or in combination of two or more. The surface cross-linking agent preferably contains a carbonate compound, more preferably contains an alkylene carbonate, and further preferably contains an ethylene carbonate, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
　上述の表面架橋工程では、１００質量部の重合体粒子群に対して下記使用量の表面架橋剤を用いて重合体粒子群に表面架橋を施すことができる。表面架橋剤の使用量は、１００質量部の重合体粒子群に対して下記の範囲が好ましい。表面架橋剤の使用量は、加圧下における優れた吸水特性を得やすい観点から、０．００５質量部以上が好ましく、０．０１質量部以上がより好ましく、０．０５質量部以上が更に好ましく、０．１質量部以上が特に好ましく、０．３質量部以上が極めて好ましく、０．５質量部以上が非常に好ましく、０．８質量部以上がより一層好ましく、１．０質量部以上が更に好ましく、１．２質量部以上が特に好ましく、１．４質量部以上が極めて好ましい。表面架橋剤の使用量は、加圧下における優れた吸水特性を得やすい観点から、１０質量部以下が好ましく、８質量部以下がより好ましく、５質量部以下が更に好ましく、４質量部以下が特に好ましく、３質量部以下が極めて好ましく、２質量部以下が非常に好ましく、１．５質量部以下がより一層好ましい。これらの観点から、表面架橋剤の使用量は、０．００５～１０質量部が好ましく、０．０１～１０質量部がより好ましく、０．０１～５質量部が更に好ましく、０．０１～３質量部が特に好ましく、０．１～３質量部が極めて好ましく、０．５～３質量部が非常に好ましい。表面架橋剤の使用量は、１～１０質量部であることも好ましい。表面架橋剤の使用量は、１．４質量部以下、１．２質量部以下、１質量部以下、又は、０．９質量部以下であってもよい。表面架橋工程では、上述の各使用量の表面架橋剤を含有する表面架橋剤溶液（表面架橋剤を含有する液）を用いて１００質量部の重合体粒子群Ｂ１に表面架橋を施すことが可能であり、例えば、１質量部以上（例えば１～１０質量部）の表面架橋剤を含有する表面架橋剤溶液を用いて１００質量部の重合体粒子群Ｂ１に表面架橋を施すことができる。 In the above-mentioned surface cross-linking step, the polymer particle group can be surface-crosslinked using the following amount of the surface cross-linking agent for 100 parts by mass of the polymer particle group. The amount of the surface cross-linking agent used is preferably in the following range with respect to 100 parts by mass of the polymer particle group. The amount of the surface cross-linking agent used is preferably 0.005 parts by mass or more, more preferably 0.01 parts by mass or more, still more preferably 0.05 parts by mass or more, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. 0.1 parts by mass or more is particularly preferable, 0.3 parts by mass or more is extremely preferable, 0.5 parts by mass or more is very preferable, 0.8 parts by mass or more is even more preferable, and 1.0 parts by mass or more is further preferable. Preferably, 1.2 parts by mass or more is particularly preferable, and 1.4 parts by mass or more is extremely preferable. The amount of the surface cross-linking agent used is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 5 parts by mass or less, and particularly preferably 4 parts by mass or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Preferably, 3 parts by mass or less is extremely preferable, 2 parts by mass or less is very preferable, and 1.5 parts by mass or less is even more preferable. From these viewpoints, the amount of the surface cross-linking agent used is preferably 0.005 to 10 parts by mass, more preferably 0.01 to 10 parts by mass, further preferably 0.01 to 5 parts by mass, and 0.01 to 3 parts. Parts by mass are particularly preferable, parts by mass of 0.1 to 3 are extremely preferable, and parts by mass of 0.5 to 3 are very preferable. The amount of the surface cross-linking agent used is preferably 1 to 10 parts by mass. The amount of the surface cross-linking agent used may be 1.4 parts by mass or less, 1.2 parts by mass or less, 1 part by mass or less, or 0.9 parts by mass or less. In the surface cross-linking step, it is possible to carry out surface cross-linking on 100 parts by mass of the polymer particle group B1 using the surface cross-linking agent solution (liquid containing the surface cross-linking agent) containing each of the above-mentioned amounts of the surface cross-linking agent. For example, 100 parts by mass of the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing 1 part by mass or more (for example, 1 to 10 parts by mass) of the surface cross-linking agent.
　上述の表面架橋工程では、１００質量部の重合体粒子群に対して下記使用量のカーボネート化合物（例えばアルキレンカーボネート）を用いて重合体粒子群に表面架橋を施すことができる。カーボネート化合物の使用量は、１００質量部の重合体粒子群に対して下記の範囲が好ましい。カーボネート化合物の使用量は、加圧下における優れた吸水特性を得やすい観点から、０．０１質量部以上が好ましく、０．０５質量部以上がより好ましく、０．１質量部以上が更に好ましく、０．３質量部以上が特に好ましく、０．５質量部以上が極めて好ましく、０．６質量部以上が非常に好ましく、０．７質量部以上がより一層好ましく、０．８質量部以上が更に好ましく、０．９質量部以上が特に好ましい。カーボネート化合物の使用量は、適正なＣＲＣを得やすい観点から、１０質量部以下が好ましく、８質量部以下がより好ましく、５質量部以下が更に好ましく、４質量部以下が特に好ましく、３質量部以下が極めて好ましく、２質量部以下が非常に好ましく、１質量部以下がより一層好ましい。これらの観点から、カーボネート化合物の使用量は、０．０１～１０質量部が好ましく、０．０１～５質量部がより好ましく、０．０１～３質量部が更に好ましく、０．１～３質量部が特に好ましく、０．５～３質量部が極めて好ましい。カーボネート化合物の使用量は、０．５～１０質量部であることも好ましい。カーボネート化合物の使用量は、０．９質量部以下、０．７質量部以下、又は、０．５質量部以下であってもよい。表面架橋工程では、上述の各使用量のカーボネート化合物を含有する表面架橋剤溶液を用いて１００質量部の重合体粒子群Ｂ１に表面架橋を施すことが可能であり、例えば、０．５質量部以上（例えば０．５～１０質量部）のカーボネート化合物を含有する表面架橋剤溶液を用いて１００質量部の重合体粒子群Ｂ１に表面架橋を施すことができる。 In the above-mentioned surface cross-linking step, the polymer particle group can be surface-crosslinked by using the following amount of a carbonate compound (for example, alkylene carbonate) with respect to 100 parts by mass of the polymer particle group. The amount of the carbonate compound used is preferably in the following range with respect to 100 parts by mass of the polymer particle group. The amount of the carbonate compound used is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, further preferably 0.1 part by mass or more, and 0, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. .3 parts by mass or more is particularly preferable, 0.5 parts by mass or more is extremely preferable, 0.6 parts by mass or more is very preferable, 0.7 parts by mass or more is further preferable, and 0.8 parts by mass or more is further preferable. , 0.9 parts by mass or more is particularly preferable. The amount of the carbonate compound used is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 5 parts by mass or less, particularly preferably 4 parts by mass or less, and 3 parts by mass from the viewpoint of easily obtaining an appropriate CRC. The following is extremely preferable, 2 parts by mass or less is very preferable, and 1 part by mass or less is even more preferable. From these viewpoints, the amount of the carbonate compound used is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, further preferably 0.01 to 3 parts by mass, and 0.1 to 3 parts by mass. Parts are particularly preferable, and 0.5 to 3 parts by mass are extremely preferable. The amount of the carbonate compound used is preferably 0.5 to 10 parts by mass. The amount of the carbonate compound used may be 0.9 parts by mass or less, 0.7 parts by mass or less, or 0.5 parts by mass or less. In the surface cross-linking step, 100 parts by mass of the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing each of the above-mentioned amounts of the carbonate compound, for example, 0.5 parts by mass. Using the surface cross-linking agent solution containing the above (for example, 0.5 to 10 parts by mass) of the carbonate compound, 100 parts by mass of the polymer particle group B1 can be surface-crosslinked.
　表面架橋工程では、重合体粒子群と表面架橋剤とを下記混合温度で混合して重合体粒子群に表面架橋を施してよい。表面架橋工程における重合体粒子群と表面架橋剤との混合温度（混合時の温度。例えば、重合体粒子群と表面架橋剤溶液との混合温度）は、下記の範囲が好ましい。混合温度は、加圧下における優れた吸水特性を得やすい観点から、０℃以上が好ましく、１℃以上がより好ましく、３℃以上が更に好ましく、５℃以上が特に好ましく、５℃以上を超えることが極めて好ましく、１０℃以上が非常に好ましく、１０℃以上を超えることがより一層好ましく、１５℃以上が更に好ましい。混合温度は、加圧下における優れた吸水特性を得やすい観点から、５０℃以下が好ましく、４５℃以下がより好ましく、４０℃以下が更に好ましく、３５℃以下が特に好ましく、３０℃以下が極めて好ましく、３０℃未満が非常に好ましく、２５℃以下がより一層好ましく、２５℃未満が更に好ましく、２０℃以下が特に好ましく、２０℃未満が極めて好ましく、１８℃以下が非常に好ましく、１５℃以下がより一層好ましい。これらの観点から、混合温度は、０～５０℃が好ましく、５～３０℃がより好ましく、１０～２５℃が更に好ましい。混合温度は、０～２０℃であることも好ましい。混合温度は、１５℃以上を超えてよく、２０℃以上であってよく、２０℃以上を超えてよく、２２℃以上であってよい。表面架橋工程では、重合体粒子群Ｂ１と表面架橋剤とを上述の各混合温度で混合して重合体粒子群Ｂ１に表面架橋を施すことが可能であり、例えば、重合体粒子群Ｂ１と表面架橋剤とを２０℃以下（例えば０～２０℃）で混合して重合体粒子群Ｂ１に表面架橋を施すことができる。 In the surface cross-linking step, the polymer particle group and the surface cross-linking agent may be mixed at the following mixing temperature to perform surface cross-linking on the polymer particle group. The mixing temperature of the polymer particle group and the surface cross-linking agent in the surface cross-linking step (temperature at the time of mixing, for example, the mixing temperature of the polymer particle group and the surface cross-linking agent solution) is preferably in the following range. The mixing temperature is preferably 0 ° C. or higher, more preferably 1 ° C. or higher, further preferably 3 ° C. or higher, particularly preferably 5 ° C. or higher, and exceeding 5 ° C. or higher from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is extremely preferable, 10 ° C. or higher is very preferable, 10 ° C. or higher is even more preferable, and 15 ° C. or higher is even more preferable. The mixing temperature is preferably 50 ° C. or lower, more preferably 45 ° C. or lower, further preferably 40 ° C. or lower, particularly preferably 35 ° C. or lower, and extremely preferably 30 ° C. or lower, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. , Less than 30 ° C. is very preferable, 25 ° C. or lower is even more preferable, less than 25 ° C. is further preferable, 20 ° C. or lower is particularly preferable, less than 20 ° C. is extremely preferable, 18 ° C. or lower is very preferable, and 15 ° C. or lower is very preferable. Even more preferable. From these viewpoints, the mixing temperature is preferably 0 to 50 ° C., more preferably 5 to 30 ° C., and even more preferably 10 to 25 ° C. The mixing temperature is also preferably 0 to 20 ° C. The mixing temperature may exceed 15 ° C. or higher, may be 20 ° C. or higher, may exceed 20 ° C. or higher, and may be 22 ° C. or higher. In the surface cross-linking step, the polymer particle group B1 and the surface cross-linking agent can be mixed at the above-mentioned mixing temperatures to perform surface cross-linking on the polymer particle group B1. For example, the polymer particle group B1 and the surface can be cross-linked. The cross-linking agent can be mixed at 20 ° C. or lower (for example, 0 to 20 ° C.) to perform surface cross-linking on the polymer particle group B1.
　表面架橋工程は、水の存在下で行ってよく、重合体粒子群における１００質量部の単量体（例えばエチレン性不飽和単量体）に対して１～２００質量部の範囲の水の存在下で行ってよい。表面架橋工程における水分量を調整することによって粒子表面近傍における架橋を調整できる。 The surface cross-linking step may be carried out in the presence of water, and the presence of water in the range of 1 to 200 parts by mass with respect to 100 parts by mass of the monomer (for example, ethylenically unsaturated monomer) in the polymer particle group. You may go below. By adjusting the amount of water in the surface cross-linking step, the cross-linking in the vicinity of the particle surface can be adjusted.
　表面架橋工程では、水溶性有機溶媒及び水からなる群より選ばれる少なくとも一種を含有する表面架橋剤溶液を用いて重合体粒子群に表面架橋を施すことができる。水溶性有機溶媒としては、アルコール等が挙げられる。アルコールとしては、メタノール、エタノール、プロパノール、イソプロパノール等の低級アルコール類；アセトン等のケトン類；ジオキサン等のエーテル類；Ｎ，Ｎ－ジメチルホルムアミド等のアミド類；ジメチルスルホキシド等のスルホキシド類；エチレングリコール、プロピレングリコール等の多価アルコール類などが挙げられる。アルコールとしては、水酸基を２個以上（例えば２個）有する化合物、及び、水酸基を１個有する化合物からなる群より選ばれる少なくとも一種を用いてよい。アルコールは、加圧下における優れた吸水特性を得やすい観点から、プロピレングリコール及びイソプロパノールからなる群より選ばれる少なくとも一種を含むことが好ましく、イソプロパノールを含むことがより好ましい。水溶性有機溶媒は、上述の表面架橋剤に該当する化合物であってもよい。表面架橋工程では、例えば、イソプロパノールを含有する表面架橋剤溶液を用いて重合体粒子群Ｂ１に表面架橋を施すことができる。 In the surface cross-linking step, the polymer particle group can be surface-crosslinked using a surface cross-linking agent solution containing at least one selected from the group consisting of a water-soluble organic solvent and water. Examples of the water-soluble organic solvent include alcohol and the like. As alcohols, lower alcohols such as methanol, ethanol, propanol and isopropanol; ketones such as acetone; ethers such as dioxane; amides such as N, N-dimethylformamide; sulfoxides such as dimethyl sulfoxide; ethylene glycol, Examples thereof include polyhydric alcohols such as propylene glycol. As the alcohol, at least one selected from the group consisting of a compound having two or more (for example, two) hydroxyl groups and a compound having one hydroxyl group may be used. The alcohol preferably contains at least one selected from the group consisting of propylene glycol and isopropanol, and more preferably isopropanol, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. The water-soluble organic solvent may be a compound corresponding to the above-mentioned surface cross-linking agent. In the surface cross-linking step, for example, the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing isopropanol.
　表面架橋工程では、アルコールを含有する表面架橋剤溶液を用いて重合体粒子群に表面架橋を施すことが可能であり、下記使用量のアルコールを含有する表面架橋剤溶液を用いて重合体粒子群に表面架橋を施すことができる。表面架橋剤溶液は、表面架橋剤であるアルコール、及び、表面架橋剤ではないアルコールからなる群より選ばれる少なくとも一種を含むことができる。 In the surface cross-linking step, it is possible to carry out surface cross-linking on the polymer particle group using a surface cross-linking agent solution containing alcohol, and the polymer particle group using the surface cross-linking agent solution containing the following amount of alcohol. Can be surface crosslinked. The surface cross-linking agent solution can contain at least one selected from the group consisting of alcohols that are surface cross-linking agents and alcohols that are not surface cross-linking agents.
　表面架橋剤溶液におけるアルコールの使用量は、表面架橋剤溶液の全質量、又は、アルコールに該当しない表面架橋剤、アルコール及び水の合計量を基準として下記の範囲が好ましい。アルコールの使用量は、加圧下における優れた吸水特性を得やすい観点から、１０質量％以上が好ましく、１２質量％以上がより好ましく、１５質量％以上が更に好ましく、１７質量％以上が特に好ましく、１８質量％以上が極めて好ましく、２０質量％以上が非常に好ましく、２２．５質量％以上がより一層好ましく、２５質量％以上が更に好ましく、２７．５質量％以上が特に好ましく、３０質量％以上が極めて好ましい。アルコールの使用量は、加圧下における優れた吸水特性を得やすい観点から、８０質量％以下が好ましく、７５質量％以下がより好ましく、７０質量％以下が更に好ましく、６５質量％以下が特に好ましく、６０質量％以下が極めて好ましく、５５質量％以下が非常に好ましく、５２質量％以下がより一層好ましい。これらの観点から、アルコールの使用量は、１０～８０質量％が好ましく、２０～７０質量％がより好ましく、２０～６０質量％が更に好ましく、３０～５５質量％が特に好ましい。アルコールの使用量は、２０～８０質量％であることも好ましい。アルコールの使用量は、３１質量％以上、３５質量％以上、４０質量％以上、４５質量％以上、５０質量％以上、又は、５１質量％以上であってよい。アルコールの使用量は、５１質量％以下、５０質量％以下、４５質量％以下、４０質量％以下、３５質量％以下、又は、３１質量％以下であってよい。表面架橋工程では、上述の各使用量のアルコールを含有する表面架橋剤溶液を用いて重合体粒子群Ｂ１に表面架橋を施すことが可能であり、例えば、アルコールを２０質量％以上（例えば２０～８０質量％）含有する表面架橋剤溶液を用いて重合体粒子群Ｂ１に表面架橋を施すことができる。 The amount of alcohol used in the surface cross-linking agent solution is preferably in the following range based on the total mass of the surface cross-linking agent solution or the total amount of the surface cross-linking agent, alcohol and water that do not correspond to alcohol. The amount of alcohol used is preferably 10% by mass or more, more preferably 12% by mass or more, further preferably 15% by mass or more, and particularly preferably 17% by mass or more, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. 18% by mass or more is extremely preferable, 20% by mass or more is very preferable, 22.5% by mass or more is further preferable, 25% by mass or more is further preferable, 27.5% by mass or more is particularly preferable, and 30% by mass or more. Is extremely preferable. The amount of alcohol used is preferably 80% by mass or less, more preferably 75% by mass or less, further preferably 70% by mass or less, and particularly preferably 65% by mass or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. 60% by mass or less is extremely preferable, 55% by mass or less is very preferable, and 52% by mass or less is even more preferable. From these viewpoints, the amount of alcohol used is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, further preferably 20 to 60% by mass, and particularly preferably 30 to 55% by mass. The amount of alcohol used is also preferably 20 to 80% by mass. The amount of alcohol used may be 31% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, 50% by mass or more, or 51% by mass or more. The amount of alcohol used may be 51% by mass or less, 50% by mass or less, 45% by mass or less, 40% by mass or less, 35% by mass or less, or 31% by mass or less. In the surface cross-linking step, it is possible to carry out surface cross-linking on the polymer particle group B1 by using the above-mentioned surface cross-linking agent solution containing each amount of alcohol used, for example, 20% by mass or more of alcohol (for example, 20 to 20 to 20). The polymer particle group B1 can be surface-crosslinked using a surface-crosslinking agent solution containing 80% by mass).
　アルコール及び水を含有する表面架橋剤溶液を用いて重合体粒子群に表面架橋を施す場合、水に対するアルコールの体積比（アルコールの体積／水の体積）は、下記の範囲が好ましい。体積比は、加圧下における優れた吸水特性を得やすい観点から、０．１０以上が好ましく、０．２０以上がより好ましく、０．２５以上が更に好ましく、０．３０以上が特に好ましく、０．３５以上が極めて好ましく、０．４０以上が非常に好ましく、０．４５以上がより一層好ましい。体積比は、加圧下における優れた吸水特性を得やすい観点から、２．００以下が好ましく、１．８０以下がより好ましく、１．５０以下が更に好ましく、１．４０以下が特に好ましく、１．３０以下が極めて好ましく、１．２０以下が非常に好ましい。これらの観点から、体積比は、０．１０～２．００が好ましく、０．２５～１．５０がより好ましく、０．４５～１．２０が更に好ましい。体積比は、０．２５～２．００であることも好ましい。体積比は、０．５０以上、０．７０以上、０．９０以上、１．００以上、１．１０以上、又は、１．２０以上であってよい。体積比は、１．２０未満、１．１０以下、１．００以下、０．９０以下、０．７０以下、０．５０以下、又は、０．３０以下であってよい。アルコールの使用量は、表面架橋剤の使用量を含む。体積比は、２０℃における体積比であってよく、２０℃におけるアルコール及び水の密度に基づき算出できる。例えば、プロピレングリコールの密度は１．０４ｇ／ｃｍ３であり、イソプロパノールの密度は０．７９ｇ／ｃｍ３である。表面架橋工程は、アルコール及び水を含有する表面架橋剤溶液を用いて重合体粒子群Ｂ１に表面架橋を施し、水に対するアルコールの体積比が上述の各体積比である態様であってよく、例えば、水に対するアルコールの体積比が０．２５以上（例えば０．２５～２．００）である態様であってよい。 When surface cross-linking is performed on a polymer particle group using a surface cross-linking agent solution containing alcohol and water, the volume ratio of alcohol to water (volume of alcohol / volume of water) is preferably in the following range. The volume ratio is preferably 0.10 or more, more preferably 0.20 or more, further preferably 0.25 or more, particularly preferably 0.30 or more, and 0. 35 or more is extremely preferable, 0.40 or more is very preferable, and 0.45 or more is even more preferable. The volume ratio is preferably 2.00 or less, more preferably 1.80 or less, further preferably 1.50 or less, particularly preferably 1.40 or less, from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. 30 or less is extremely preferable, and 1.20 or less is very preferable. From these viewpoints, the volume ratio is preferably 0.10 to 2.00, more preferably 0.25 to 1.50, and even more preferably 0.45 to 1.20. The volume ratio is also preferably 0.25 to 2.00. The volume ratio may be 0.50 or more, 0.70 or more, 0.90 or more, 1.00 or more, 1.10 or more, or 1.20 or more. The volume ratio may be less than 1.20, 1.10 or less, 1.00 or less, 0.90 or less, 0.70 or less, 0.50 or less, or 0.30 or less. The amount of alcohol used includes the amount of surface cross-linking agent used. The volume ratio may be a volume ratio at 20 ° C. and can be calculated based on the density of alcohol and water at 20 ° C. For example, the density of propylene glycol is 1.04 g / cm 3 , and the density of isopropanol is 0.79 g / cm 3 . The surface cross-linking step may be an embodiment in which the polymer particle group B1 is subjected to surface cross-linking using a surface cross-linking agent solution containing alcohol and water, and the volume ratio of alcohol to water is each of the above-mentioned volume ratios, for example. , The volume ratio of alcohol to water may be 0.25 or more (for example, 0.25 to 2.00).
　アルコールの使用量は、１００質量部の重合体粒子群に対して下記の範囲が好ましい。アルコールの使用量は、加圧下における優れた吸水特性を得やすい観点から、０．１質量部以上が好ましく、０．１５質量部以上がより好ましく、０．２５質量部以上が更に好ましく、０．５質量部以上が特に好ましく、０．６質量部以上が極めて好ましく、０．７５質量部以上が非常に好ましく、１質量部以上がより一層好ましく、１．２５質量部以上が更に好ましく、１．５質量部以上が特に好ましく、１．７５質量部以上が極めて好ましく、２質量部以上が非常に好ましく、２．２５質量部以上がより一層好ましく、２．５質量部以上が更に好ましい。アルコールの使用量は、加圧下における優れた吸水特性を得やすい観点から、５質量部以下が好ましく、４．５質量部以下がより好ましく、４質量部以下が更に好ましく、３．５質量部以下が特に好ましく、３質量部以下が極めて好ましく、２．６質量部以下が非常に好ましい。これらの観点から、アルコールの使用量は、０．１～５質量部が好ましく、０．５～４質量部がより好ましく、１～３質量部が更に好ましい。アルコールの使用量は、２．５質量部以下、２質量部以下、１．５質量部以下、１．１質量部以下、０．８質量部以下、又は、０．６質量部以下であってもよい。アルコールの使用量は、表面架橋剤の使用量を含む。表面架橋工程では、上述の各使用量のアルコールを含有する表面架橋剤溶液を用いて１００質量部の重合体粒子群Ｂ１に表面架橋を施すことが可能であり、例えば、０．６質量部以上（例えば０．６～５質量部）のアルコールを含有する表面架橋剤溶液を用いて１００質量部の重合体粒子群Ｂ１に表面架橋を施すことができる。 The amount of alcohol used is preferably in the following range with respect to 100 parts by mass of the polymer particle group. The amount of alcohol used is preferably 0.1 part by mass or more, more preferably 0.15 part by mass or more, further preferably 0.25 part by mass or more, and 0. 5 parts by mass or more is particularly preferable, 0.6 parts by mass or more is extremely preferable, 0.75 parts by mass or more is very preferable, 1 part by mass or more is further preferable, and 1.25 parts by mass or more is further preferable. 5 parts by mass or more is particularly preferable, 1.75 parts by mass or more is extremely preferable, 2 parts by mass or more is very preferable, 2.25 parts by mass or more is further preferable, and 2.5 parts by mass or more is further preferable. The amount of alcohol used is preferably 5 parts by mass or less, more preferably 4.5 parts by mass or less, further preferably 4 parts by mass or less, and 3.5 parts by mass or less from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. Is particularly preferable, 3 parts by mass or less is extremely preferable, and 2.6 parts by mass or less is very preferable. From these viewpoints, the amount of alcohol used is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 4 parts by mass, and even more preferably 1 to 3 parts by mass. The amount of alcohol used is 2.5 parts by mass or less, 2 parts by mass or less, 1.5 parts by mass or less, 1.1 parts by mass or less, 0.8 parts by mass or less, or 0.6 parts by mass or less. May be good. The amount of alcohol used includes the amount of surface cross-linking agent used. In the surface cross-linking step, it is possible to carry out surface cross-linking on 100 parts by mass of the polymer particle group B1 using the above-mentioned surface cross-linking agent solution containing each amount of alcohol, for example, 0.6 parts by mass or more. 100 parts by mass of the polymer particle group B1 can be surface-crosslinked using a surface cross-linking agent solution containing (for example, 0.6 to 5 parts by mass) alcohol.
　表面架橋工程における処理温度は、使用する表面架橋剤に応じて適宜設定され、２０～２５０℃であってよい。表面架橋工程における処理温度は、表面架橋剤の沸点又は分解温度より低い温度であることが好ましい。処理時間は、１～２００分が好ましく、５～１００分がより好ましく、５～６０分が更に好ましく、５～４５分が特に好ましい。表面架橋が施された重合体粒子群は、粗大粒子を取り除く観点から、目開き８５０μｍの篩で分級されてもよい。表面架橋が施された重合体粒子群は、極めて小さい微粉を取り除く観点から、目開き４５μｍの篩で分級されてもよい。 The treatment temperature in the surface cross-linking step is appropriately set according to the surface cross-linking agent used, and may be 20 to 250 ° C. The treatment temperature in the surface cross-linking step is preferably a temperature lower than the boiling point or decomposition temperature of the surface cross-linking agent. The treatment time is preferably 1 to 200 minutes, more preferably 5 to 100 minutes, further preferably 5 to 60 minutes, and particularly preferably 5 to 45 minutes. The surface-crosslinked polymer particle group may be classified by a sieve having an opening of 850 μm from the viewpoint of removing coarse particles. The surface-crosslinked polymer particle group may be classified by a sieve having a mesh size of 45 μm from the viewpoint of removing extremely small fine powder.
　本実施形態によれば、目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した重合体粒子群Ｂ１に表面架橋を施す表面架橋工程を備える、重合体粒子（重合体粒子群Ｂ２）の製造方法を提供することができる。当該重合体粒子の製造方法は、微粉の製造方法又は微粉の架橋方法であるともいえる。本実施形態に係る重合体粒子の製造方法によれば、吸水特性に優れた微粉として、加圧下における優れた吸水特性を有する重合体粒子を得ることが可能であり、微粉を有効に活用することができる。本実施形態に係る重合体粒子の製造方法によれば、吸水特性に優れた微粉として、加圧下における優れた吸水特性に加えて優れたＣＲＣを有する重合体粒子を得ることもできる。 According to the present embodiment, the polymer particles (polymer) comprising a surface cross-linking step of subjecting the polymer particle group B1 that has passed through the sieve when the polymer particle group is classified by a sieve having a mesh size of 212 μm or less. A method for producing the particle group B2) can be provided. It can be said that the method for producing the polymer particles is a method for producing fine powder or a method for cross-linking fine powder. According to the method for producing polymer particles according to the present embodiment, it is possible to obtain polymer particles having excellent water absorption characteristics under pressure as fine powders having excellent water absorption characteristics, and the fine powders can be effectively utilized. Can be done. According to the method for producing polymer particles according to the present embodiment, polymer particles having excellent CRC in addition to excellent water absorption characteristics under pressure can be obtained as fine powder having excellent water absorption characteristics.
　本実施形態に係る重合体粒子の製造方法の表面架橋工程における表面架橋の条件としては、本実施形態に係る吸水性樹脂粒子の製造方法の表面架橋工程に関して上述した条件と同一の条件を任意に用いることができる。 As the surface cross-linking condition in the surface cross-linking step of the polymer particle manufacturing method according to the present embodiment, the same conditions as the above-mentioned conditions for the surface cross-linking step of the water-absorbent resin particle manufacturing method according to the present embodiment can be arbitrarily set. Can be used.
　例えば、本実施形態に係る重合体粒子の製造方法は、吸水性樹脂粒子の製造方法における表面架橋剤に関する上述の各使用量の表面架橋剤を含有する表面架橋剤溶液を用いて、目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した１００質量部の重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよく、例えば、１質量部以上（例えば１～１０質量部）の表面架橋剤を含有する表面架橋剤溶液を用いて１００質量部の重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよい。 For example, in the method for producing polymer particles according to the present embodiment, a surface cross-linking agent solution containing each of the above-mentioned amounts of the surface cross-linking agent used for the surface cross-linking agent in the method for producing water-absorbent resin particles is used, and the opening is 212 μm. The embodiment may include a step of subjecting 100 parts by mass of the polymer particle group B1 that has passed through the sieve to surface crosslink when the polymer particle group is classified by the following sieve, for example, 1 part by mass or more (for example, 1). It may be an embodiment including a step of subjecting 100 parts by mass of the polymer particle group B1 to surface cross-linking using a surface cross-linking agent solution containing (~ 10 parts by mass) of the surface cross-linking agent.
　本実施形態に係る重合体粒子の製造方法は、吸水性樹脂粒子の製造方法におけるカーボネート化合物に関する上述の各使用量のカーボネート化合物（例えばアルキレンカーボネート）を含有する表面架橋剤溶液を用いて、目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した１００質量部の重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよく、例えば、０．５質量部以上（例えば０．５～１０質量部）のカーボネート化合物（例えばアルキレンカーボネート）を含有する表面架橋剤溶液を用いて１００質量部の重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよい。 In the method for producing polymer particles according to the present embodiment, a surface cross-linking agent solution containing each of the above-mentioned amounts of the carbonate compound (for example, alkylene carbonate) used for the carbonate compound in the method for producing water-absorbent resin particles is used to open the openings. The embodiment may include a step of surface cross-linking 100 parts by mass of the polymer particle group B1 that has passed through the sieve when the polymer particle group is classified with a sieve of 212 μm or less, for example, 0.5 parts by mass or more. An embodiment may include a step of surface cross-linking 100 parts by mass of the polymer particle group B1 with a surface cross-linking agent solution containing a carbonate compound (for example, alkylene carbonate) of (for example, 0.5 to 10 parts by mass). ..
　本実施形態に係る重合体粒子の製造方法は、目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した重合体粒子群Ｂ１と、表面架橋剤と、を吸水性樹脂粒子の製造方法における上述の各混合温度で混合して重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよく、例えば、重合体粒子群Ｂ１と表面架橋剤とを２０℃以下（例えば０～２０℃）で混合して重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよい。 In the method for producing polymer particles according to the present embodiment, when the polymer particle group is classified by a sieve having a mesh size of 212 μm or less, the polymer particle group B1 that has passed through the sieve and the surface cross-linking agent are combined with a water-absorbent resin. The embodiment may include a step of subjecting the polymer particle group B1 to surface cross-linking by mixing at each of the above-mentioned mixing temperatures in the method for producing particles. For example, the polymer particle group B1 and the surface cross-linking agent are heated to 20 ° C. or lower ( For example, it may be an embodiment including a step of subjecting the polymer particle group B1 to surface cross-linking by mixing at 0 to 20 ° C.).
　本実施形態に係る重合体粒子の製造方法は、イソプロパノールを含有する表面架橋剤溶液を用いて、目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよい。 In the method for producing polymer particles according to the present embodiment, a polymer particle group that has passed through the sieve when the polymer particle group is classified by a sieve having a mesh size of 212 μm or less using a surface cross-linking agent solution containing isopropanol. It may be an embodiment including a step of subjecting B1 to surface cross-linking.
　本実施形態に係る重合体粒子の製造方法は、吸水性樹脂粒子の製造方法におけるアルコールに関する上述の各使用量（表面架橋剤溶液の全質量、又は、アルコールに該当しない表面架橋剤、アルコール及び水の合計量を基準とした使用量、及び、１００質量部の重合体粒子群に対する使用量）のアルコールを含有する表面架橋剤溶液を用いて、目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよく、例えば、アルコールを２０質量％以上（例えば２０～８０質量％）含有する表面架橋剤溶液を用いて１００質量部の重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよく、０．６質量部以上（例えば０．６～５質量部）のアルコールを含有する表面架橋剤溶液を用いて１００質量部の重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよい。 In the method for producing the polymer particles according to the present embodiment, the above-mentioned amounts of alcohol used in the method for producing the water-absorbent resin particles (the total mass of the surface cross-linking agent solution, or the surface cross-linking agent, alcohol and water which do not correspond to alcohol). The polymer particle group is classified with a sieve having a mesh size of 212 μm or less by using a surface cross-linking agent solution containing alcohol (the amount used based on the total amount of the above and the amount used with respect to 100 parts by mass of the polymer particle group). The embodiment may include a step of subjecting the polymer particle group B1 that has passed through the sieve to crosslink the surface. For example, a surface crosslinking agent solution containing 20% by mass or more (for example, 20 to 80% by mass) of alcohol. A surface cross-linking agent solution containing 0.6 parts by mass or more (for example, 0.6 to 5 parts by mass) of alcohol may be provided, which may include a step of subjecting 100 parts by mass of the polymer particle group B1 to surface cross-linking. It may be an embodiment including a step of subjecting 100 parts by mass of the polymer particle group B1 to surface crosslinks using the above.
　本実施形態に係る重合体粒子の製造方法は、アルコール及び水を含有する表面架橋剤溶液を用いて、目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した重合体粒子群Ｂ１に表面架橋を施す工程を備える態様であってよく、水に対するアルコールの体積比は、吸水性樹脂粒子の製造方法における上述の各体積比であってよく、例えば、０．２５以上（例えば０．２５～２．００）であってよい。 In the method for producing polymer particles according to the present embodiment, when a polymer particle group is classified with a sieve having a mesh size of 212 μm or less using a surface cross-linking agent solution containing alcohol and water, the polymer passed through the sieve. The embodiment may include a step of subjecting the particle group B1 to surface crosslink, and the volume ratio of the alcohol to water may be each of the above-mentioned volume ratios in the method for producing the water-absorbent resin particles, for example, 0.25 or more ( For example, it may be 0.25 to 2.00).
　本実施形態に係る吸水性樹脂粒子の製造方法に関するこれら以外の他の各条件についても、本実施形態に係る重合体粒子の製造方法の表面架橋工程で任意に採用することができる。 Other conditions other than these regarding the method for producing water-absorbent resin particles according to the present embodiment can also be arbitrarily adopted in the surface cross-linking step of the method for producing polymer particles according to the present embodiment.
　本実施形態に係る吸水性樹脂粒子の製造方法は、分級工程、表面架橋工程及び混合工程の前に、篩Ｓ１又は篩Ｓ２を用いた分級の対象である重合体粒子群を得るための架橋重合体ゲルを得る重合工程を備えてよい。重合工程では、例えば、エチレン性不飽和単量体を含有する単量体組成物を重合することができる。 The method for producing water-absorbent resin particles according to the present embodiment is a cross-linking weight for obtaining a polymer particle group to be classified using a sieve S1 or a sieve S2 before a classification step, a surface cross-linking step and a mixing step. It may be provided with a polymerization step to obtain a coalesced gel. In the polymerization step, for example, a monomer composition containing an ethylenically unsaturated monomer can be polymerized.
　単量体組成物は、水、有機溶媒等を含有してよい。単量体組成物は、単量体水溶液であってよい。単量体組成物の重合方法としては、水溶液重合法、バルク重合法等が挙げられる。これらの中では、良好な吸水特性（加圧下における優れた吸水特性等）が得られやすい観点、及び、重合反応の制御が容易である観点から、水溶液重合法が好ましい。以下においては、重合方法の一例として水溶液重合法を用いた場合について説明する。 The monomer composition may contain water, an organic solvent, and the like. The monomer composition may be a monomer aqueous solution. Examples of the polymerization method of the monomer composition include an aqueous solution polymerization method and a bulk polymerization method. Among these, the aqueous solution polymerization method is preferable from the viewpoint that good water absorption characteristics (excellent water absorption characteristics under pressure, etc.) can be easily obtained and the polymerization reaction can be easily controlled. In the following, a case where the aqueous solution polymerization method is used as an example of the polymerization method will be described.
　エチレン性不飽和単量体としては、水溶性エチレン性不飽和単量体を用いることができる。エチレン性不飽和単量体としては、（メタ）アクリル酸、マレイン酸、無水マレイン酸、フマル酸等のα，β－不飽和カルボン酸、及び、その塩などのカルボン酸系単量体；（メタ）アクリルアミド、Ｎ，Ｎ－ジメチル（メタ）アクリルアミド、２－ヒドロキシエチル（メタ）アクリレート、Ｎ－メチロール（メタ）アクリルアミド、ポリエチレングリコールモノ（メタ）アクリレート等の非イオン性単量体；Ｎ，Ｎ－ジエチルアミノエチル（メタ）アクリレート、Ｎ，Ｎ－ジエチルアミノプロピル（メタ）アクリレート、ジエチルアミノプロピル（メタ）アクリルアミド等のアミノ基含有不飽和単量体、及び、その第４級化物；ビニルスルホン酸、スチレンスルホン酸、２－（メタ）アクリルアミド－２－メチルプロパンスルホン酸、２－（メタ）アクリロイルエタンスルホン酸、及び、それらの塩等のスルホン酸系単量体などが挙げられる。エチレン性不飽和単量体は、工業的に入手が容易である観点から、（メタ）アクリル酸及びその塩からなる群より選ばれる少なくとも一種の（メタ）アクリル酸化合物を含むことが好ましい。エチレン性不飽和単量体は、（メタ）アクリル酸、及び、（メタ）アクリル酸の塩の双方を含んでよい。α，β－不飽和カルボン酸（（メタ）アクリル酸等）の塩としては、アルカリ金属塩（ナトリウム塩、カリウム塩等）、アルカリ土類金属塩（カルシウム塩等）などが挙げられる。 As the ethylenically unsaturated monomer, a water-soluble ethylenically unsaturated monomer can be used. Examples of the ethylenically unsaturated monomer include α, β-unsaturated carboxylic acids such as (meth) acrylate, maleic acid, maleic anhydride, and fumaric acid, and carboxylic acid-based monomers such as salts thereof; Nonionic monomers such as meta) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, N-methylol (meth) acrylamide, polyethylene glycol mono (meth) acrylate; N, N -Amino group-containing unsaturated monomers such as diethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylamide, and quaternary products thereof; vinyl sulfonic acid, styrene sulfone. Examples thereof include acids, 2- (meth) acrylamide-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, and sulfonic acid-based monomers such as salts thereof. The ethylenically unsaturated monomer preferably contains at least one (meth) acrylic acid compound selected from the group consisting of (meth) acrylic acid and salts thereof from the viewpoint of industrial availability. The ethylenically unsaturated monomer may contain both (meth) acrylic acid and a salt of (meth) acrylic acid. Examples of salts of α, β-unsaturated carboxylic acid ((meth) acrylic acid, etc.) include alkali metal salts (sodium salt, potassium salt, etc.), alkaline earth metal salts (calcium salt, etc.) and the like.
　酸基を有するエチレン性不飽和単量体（（メタ）アクリル酸等）は、酸基が予めアルカリ性中和剤により中和されていてよい。アルカリ性中和剤としては、水酸化ナトリウム、炭酸ナトリウム、炭酸水素ナトリウム、水酸化カリウム、炭酸カリウム等のアルカリ金属塩；アンモニアなどが挙げられる。アルカリ性中和剤は、中和操作を簡便化するために水溶液の状態にして用いてもよい。酸基の中和は、原料であるエチレン性不飽和単量体の重合前に行ってもよく、重合中又は重合後に行ってもよい。 The ethylenically unsaturated monomer having an acid group ((meth) acrylic acid, etc.) may have the acid group neutralized in advance with an alkaline neutralizer. Examples of the alkaline neutralizing agent include alkali metal salts such as sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide and potassium carbonate; ammonia and the like. The alkaline neutralizer may be used in the form of an aqueous solution in order to simplify the neutralization operation. The acid group may be neutralized before the polymerization of the ethylenically unsaturated monomer as a raw material, or during or after the polymerization.
　アルカリ性中和剤によるエチレン性不飽和単量体の中和度は、浸透圧を高めることで良好な吸水特性（加圧下における吸水特性等）が得られやすい観点、及び、余剰のアルカリ性中和剤の存在に起因する不具合を抑制する観点から、１０～１００モル％、３０～９０モル％、４０～８５モル％、又は、５０～８０モル％が好ましい。「中和度」は、エチレン性不飽和単量体が有する全ての酸基に対する中和度とする。 The degree of neutralization of the ethylenically unsaturated monomer by the alkaline neutralizer is from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained by increasing the osmotic pressure, and the excess alkaline neutralizer. From the viewpoint of suppressing defects caused by the presence of, 10 to 100 mol%, 30 to 90 mol%, 40 to 85 mol%, or 50 to 80 mol% is preferable. The "neutralization degree" is the neutralization degree for all the acid groups of the ethylenically unsaturated monomer.
　（メタ）アクリル酸化合物の含有量は、単量体組成物の全質量を基準として下記の範囲が好ましい。（メタ）アクリル酸化合物の含有量は、加圧下における優れた吸水特性を得やすい観点から、１０質量％以上、１５質量％以上、２０質量％以上、２５質量％以上、３０質量％以上、又は、３５質量％以上が好ましい。（メタ）アクリル酸化合物の含有量は、良好な吸水特性（加圧下における吸水特性等）が得られやすい観点から、６０質量％以下、５５質量％以下、５０質量％以下、５０質量％未満、４５質量％以下、又は、４０質量％以下が好ましい。これらの観点から、（メタ）アクリル酸化合物の含有量は、１０～６０質量％が好ましい。 The content of the (meth) acrylic acid compound is preferably in the following range based on the total mass of the monomer composition. The content of the (meth) acrylic acid compound is 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, or from the viewpoint of easily obtaining excellent water absorption characteristics under pressure. , 35% by mass or more is preferable. The content of the (meth) acrylic acid compound is 60% by mass or less, 55% by mass or less, 50% by mass or less, less than 50% by mass from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained. It is preferably 45% by mass or less, or 40% by mass or less. From these viewpoints, the content of the (meth) acrylic acid compound is preferably 10 to 60% by mass.
　（メタ）アクリル酸化合物の含有量は、単量体組成物に含有される単量体の合計量、及び／又は、単量体組成物に含有されるエチレン性不飽和単量体の合計量を基準として下記の範囲が好ましい。（メタ）アクリル酸化合物の含有量は、５０モル％以上、７０モル％以上、９０モル％以上、９５モル％以上、９７モル％以上、又は、９９モル％以上が好ましい。単量体組成物に含有される単量体、及び／又は、単量体組成物に含有されるエチレン性不飽和単量体は、実質的に（メタ）アクリル酸化合物からなる態様（実質的に、単量体組成物に含有される単量体、及び／又は、単量体組成物に含有されるエチレン性不飽和単量体の１００モル％が（メタ）アクリル酸化合物である態様）であってもよい。本実施形態に係る吸水性樹脂粒子において、（メタ）アクリル酸化合物に由来する構造単位の含有量は、吸水性樹脂粒子を構成する構造単位の全質量を基準として、上述の（メタ）アクリル酸化合物の含有量（単量体組成物に含有される単量体の合計量、及び／又は、単量体組成物に含有されるエチレン性不飽和単量体の合計量を基準とした（メタ）アクリル酸化合物の含有量）に関する上述の各範囲であることが好ましい。 The content of the (meth) acrylic acid compound is the total amount of the monomers contained in the monomer composition and / or the total amount of the ethylenically unsaturated monomer contained in the monomer composition. The following range is preferable with reference to. The content of the (meth) acrylic acid compound is preferably 50 mol% or more, 70 mol% or more, 90 mol% or more, 95 mol% or more, 97 mol% or more, or 99 mol% or more. The monomer contained in the monomer composition and / or the ethylenically unsaturated monomer contained in the monomer composition is substantially composed of a (meth) acrylic acid compound (substantially). In addition, 100 mol% of the monomer contained in the monomer composition and / or the ethylenically unsaturated monomer contained in the monomer composition is a (meth) acrylic acid compound). It may be. In the water-absorbent resin particles according to the present embodiment, the content of the structural unit derived from the (meth) acrylic acid compound is the above-mentioned (meth) acrylic acid based on the total mass of the structural units constituting the water-absorbent resin particles. The content of the compound (the total amount of monomers contained in the monomer composition and / or the total amount of ethylenically unsaturated monomers contained in the monomer composition was used as a reference (meth). ) Content of acrylic acid compound) is preferably in each of the above ranges.
　単量体組成物は、重合開始剤を含有してよい。単量体組成物に含まれる単量体の重合は、単量体組成物に重合開始剤を添加し、必要により加熱、光照射等を行うことで開始してよい。重合開始剤としては、光重合開始剤、ラジカル重合開始剤等が挙げられ、水溶性ラジカル重合開始剤が好ましい。重合開始剤は、良好な吸水特性（加圧下における吸水特性等）が得られやすい観点から、アゾ系化合物及び過酸化物からなる群より選ばれる少なくとも一種を含むことが好ましく、過酸化物を含むことがより好ましい。 The monomer composition may contain a polymerization initiator. The polymerization of the monomer contained in the monomer composition may be started by adding a polymerization initiator to the monomer composition and, if necessary, heating, irradiating with light or the like. Examples of the polymerization initiator include a photopolymerization initiator and a radical polymerization initiator, and a water-soluble radical polymerization initiator is preferable. The polymerization initiator preferably contains at least one selected from the group consisting of azo compounds and peroxides from the viewpoint of easily obtaining good water absorption characteristics (water absorption characteristics under pressure, etc.), and contains peroxides. Is more preferable.
　アゾ系化合物としては、２，２’－アゾビス［２－（Ｎ－フェニルアミジノ）プロパン］二塩酸塩、２，２’－アゾビス｛２－［Ｎ－（４－クロロフェニル）アミジノ］プロパン｝二塩酸塩、２，２’－アゾビス｛２－［Ｎ－（４－ヒドロキシフェニル）アミジノ］プロパン｝二塩酸塩、２，２’－アゾビス［２－（Ｎ－ベンジルアミジノ）プロパン］二塩酸塩、２，２’－アゾビス［２－（Ｎ－アリルアミジノ）プロパン］二塩酸塩、２，２’－アゾビス（２－アミジノプロパン）二塩酸塩、２，２’－アゾビス｛２－［Ｎ－（２－ヒドロキシエチル）アミジノ］プロパン｝二塩酸塩、２，２’－アゾビス［２－（５－メチル－２－イミダゾリン－２－イル）プロパン］二塩酸塩、２，２’－アゾビス［２－（２－イミダゾリン－２－イル）プロパン］二塩酸塩、２，２’－アゾビス［２－（４，５，６，７－テトラヒドロ－１Ｈ－１，３－ジアゼピン－２－イル）プロパン］二塩酸塩、２，２’－アゾビス［２－（５－ヒドロキシ－３，４，５，６－テトラヒドロピリミジン－２－イル）プロパン］二塩酸塩、２，２’－アゾビス｛２－［１－（２－ヒドロキシエチル）－２－イミダゾリン－２－イル］プロパン｝二塩酸塩、２，２’－アゾビス［２－（２－イミダゾリン－２－イル）プロパン］二硫酸塩二水和物、２，２’－アゾビス［Ｎ－（２－カルボキシエチル）－２－メチルプロピオンアミジン］四水和物、２，２’－アゾビス［２－メチル－Ｎ－（２－ヒドロキシエチル）プロピオンアミド］等が挙げられる。アゾ系化合物は、良好な吸水特性（加圧下における吸水特性等）が得られやすい観点から、２，２’－アゾビス（２－メチルプロピオンアミド）二塩酸塩、２，２’－アゾビス（２－アミジノプロパン）二塩酸塩、２，２’－アゾビス｛２－［１－（２－ヒドロキシエチル）－２－イミダゾリン－２－イル］プロパン｝二塩酸塩、及び、２，２’－アゾビス［Ｎ－（２－カルボキシエチル）－２－メチルプロピオンアミジン］四水和物からなる群より選ばれる少なくとも一種を含むことが好ましい。 Examples of the azo compound include 2,2'-azobis [2- (N-phenylamidino) propane] dihydrochloride and 2,2'-azobis {2- [N- (4-chlorophenyl) amidino] propane} dihydrochloride. Salt, 2,2'-azobis {2- [N- (4-hydroxyphenyl) amidino] propane} dihydrochloride, 2,2'-azobis [2- (N-benzylamidino) propane] dihydrochloride, 2 , 2'-azobis [2- (N-allylamidino) propane] dihydrochloride, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis {2- [N- (2) -Hydroxyethyl) amidino] propane} dihydrochloride, 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2-( 2-Imidazoline-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (4,5,6,7-tetrahydro-1H-1,3-diazepine-2-yl) propane] dihydrochloride Salt, 2,2'-azobis [2- (5-hydroxy-3,4,5,6-tetrahydropyrimidine-2-yl) propane] dihydrochloride, 2,2'-azobis {2- [1-( 2-Hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2, 2'-azobis [N- (2-carboxyethyl) -2-methylpropion amidine] tetrahydrate, 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide] and the like can be mentioned. Be done. The azo compounds are 2,2'-azobis (2-methylpropionamide) dihydrochloride and 2,2'-azobis (2-) from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained. Amidinopropane) dihydrochloride, 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, and 2,2'-azobis [N -(2-carboxyethyl) -2-methylpropion amidine] It is preferable to contain at least one selected from the group consisting of tetrahydrate.
　過酸化物としては、過硫酸カリウム、過硫酸アンモニウム、過硫酸ナトリウム等の過硫酸塩類；メチルエチルケトンパーオキシド、メチルイソブチルケトンパーオキシド、ジ－ｔ－ブチルパーオキシド、ｔ－ブチルクミルパーオキシド、ｔ－ブチルパーオキシアセテート、ｔ－ブチルパーオキシイソブチレート、ｔ－ブチルパーオキシピバレート等の有機過酸化物類などが挙げられる。過酸化物は、良好な吸水特性（加圧下における吸水特性等）が得られやすい観点から、過硫酸カリウム、過硫酸アンモニウム、及び、過硫酸ナトリウムからなる群より選ばれる少なくとも一種を含むことが好ましい。 Peroxides include persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate; methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, t-butyl. Examples thereof include organic peroxides such as peroxyacetate, t-butylperoxyisobutyrate, and t-butylperoxypivalate. The peroxide preferably contains at least one selected from the group consisting of potassium persulfate, ammonium persulfate, and sodium persulfate from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained.
　重合開始剤の含有量は、（メタ）アクリル酸化合物１モルに対して、下記の範囲が好ましい。重合開始剤の含有量は、良好な吸水特性（加圧下における吸水特性等）が得られやすい観点、及び、重合反応時間を短縮する観点から、０．００１ミリモル以上、０．００３ミリモル以上、０．０１５ミリモル以上、０．０３ミリモル以上、０．０６ミリモル以上、０．０８ミリモル以上、０．１ミリモル以上、０．１５ミリモル以上、０．２ミリモル以上、又は、０．２５ミリモル以上が好ましい。重合開始剤の含有量は、良好な吸水特性（加圧下における吸水特性等）が得られやすい観点、及び、急激な重合反応を回避しやすい観点から、５ミリモル以下、４ミリモル以下、２ミリモル以下、１ミリモル以下、又は、０．８ミリモル以下が好ましい。これらの観点から、重合開始剤の含有量は、０．００１～５ミリモルが好ましい。 The content of the polymerization initiator is preferably in the following range with respect to 1 mol of the (meth) acrylic acid compound. The content of the polymerization initiator is 0.001 mmol or more, 0.003 mmol or more, 0 from the viewpoint of easily obtaining good water absorption characteristics (water absorption characteristics under pressure, etc.) and shortening the polymerization reaction time. .015 mmol or more, 0.03 mmol or more, 0.06 mmol or more, 0.08 mmol or more, 0.1 mmol or more, 0.15 mmol or more, 0.2 mmol or more, or 0.25 mmol or more is preferable. .. The content of the polymerization initiator is 5 mmol or less, 4 mmol or less, 2 mmol or less from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained and a rapid polymerization reaction can be easily avoided. It is preferably 1 mmol or less, or 0.8 mmol or less. From these viewpoints, the content of the polymerization initiator is preferably 0.001 to 5 mmol.
　単量体組成物は、還元剤を含有してよい。還元剤としては、亜硫酸ナトリウム、亜硫酸水素ナトリウム、硫酸第１鉄、Ｌ－アスコルビン酸等が挙げられる。重合開始剤と還元剤とを併用してよい。 The monomer composition may contain a reducing agent. Examples of the reducing agent include sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, L-ascorbic acid and the like. A polymerization initiator and a reducing agent may be used in combination.
　単量体組成物は、酸化剤を含有してよい。酸化剤としては、過酸化水素、過ホウ酸ナトリウム、過リン酸及びその塩、過マンガン酸カリウム等が挙げられる。 The monomer composition may contain an oxidizing agent. Examples of the oxidizing agent include hydrogen peroxide, sodium perborate, perphosphoric acid and salts thereof, potassium permanganate and the like.
　単量体組成物は、内部架橋剤を含有してよい。内部架橋剤を用いることにより、得られる架橋重合体が、その内部架橋構造として、重合反応による自己架橋構造に加え、内部架橋剤による架橋構造を有することができる。 The monomer composition may contain an internal cross-linking agent. By using the internal cross-linking agent, the obtained cross-linking polymer can have a cross-linking structure by the internal cross-linking agent in addition to the self-cross-linking structure by the polymerization reaction as the internal cross-linking structure.
　内部架橋剤としては、反応性官能基（例えば重合性不飽和基）を２個以上有する化合物等が挙げられる。内部架橋剤としては、（ポリ）エチレングリコール、（ポリ）プロピレングリコール、トリメチロールプロパン、グリセリンポリオキシエチレングリコール、ポリオキシプロピレングリコール、（ポリ）グリセリン等のポリオールのジ又はトリ（メタ）アクリル酸エステル類；上記ポリオールと不飽和酸（マレイン酸、フマル酸等）とを反応させて得られる不飽和ポリエステル類；（ポリ）エチレングリコールジグリシジルエーテル、（ポリ）プロピレングリコールジグリシジルエーテル、（ポリ）グリセリンジグリシジルエーテル、グリシジル（メタ）アクリレート等のグリシジル基含有化合物；Ｎ，Ｎ’－メチレンビス（メタ）アクリルアミド等のビスアクリルアミド類；ポリエポキシドと（メタ）アクリル酸とを反応させて得られるジ又はトリ（メタ）アクリル酸エステル類；ポリイソシアネート（トリレンジイソシアネート、ヘキサメチレンジイソシアネート等）と（メタ）アクリル酸ヒドロキシエチルとを反応させて得られるジ（メタ）アクリル酸カルバミルエステル類；アリル化澱粉；アリル化セルロース；ジアリルフタレート；Ｎ，Ｎ’，Ｎ”－トリアリルイソシアヌレート；ジビニルベンゼン；ペンタエリスリトール；エチレンジアミン；ポリエチレンイミンなどが挙げられる。内部架橋剤は、良好な吸水特性（加圧下における吸水特性等）が得られやすい観点から、ポリエチレングリコールジ（メタ）アクリレート、トリメチロールプロパントリ（メタ）アクリレート、（ポリ）エチレングリコールジグリシジルエーテル、（ポリ）プロピレングリコールジグリシジルエーテル、及び、（ポリ）グリセリンジグリシジルエーテルからなる群より選ばれる少なくとも一種を含むことが好ましい。 Examples of the internal cross-linking agent include compounds having two or more reactive functional groups (for example, polymerizable unsaturated groups). Examples of the internal cross-linking agent include di or tri (meth) acrylic acid esters of polyols such as (poly) ethylene glycol, (poly) propylene glycol, trimethylolpropane, glycerin polyoxyethylene glycol, polyoxypropylene glycol, and (poly) glycerin. Classes; unsaturated polyesters obtained by reacting the above polyol with an unsaturated acid (maleic acid, fumaric acid, etc.); (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin. Glycidyl group-containing compounds such as diglycidyl ether and glycidyl (meth) acrylate; bisacrylamides such as N, N'-methylenebis (meth) acrylamide; di or tri (meth) obtained by reacting polyepoxide with (meth) acrylic acid. Meta) acrylic acid esters; di (meth) acrylic acid carbamil esters obtained by reacting polyisocyanates (tolylene diisocyanate, hexamethylene diisocyanate, etc.) with hydroxyethyl (meth) acrylic acid; allylated starch; allyl Cellified cellulose; diallyl phthalate; N, N', N "-triallyl isocyanurate; divinylbenzene; pentaerythritol; ethylenediamine; polyethyleneimine, etc. The internal cross-linking agent has good water absorption characteristics (water absorption characteristics under pressure, etc.). ) Is easily obtained, polyethylene glycol di (meth) acrylate, trimethylolpropantri (meth) acrylate, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerinji. It preferably contains at least one selected from the group consisting of glycidyl ethers.
　内部架橋剤の含有量は、（メタ）アクリル酸化合物１モルに対して下記の範囲が好ましい。内部架橋剤の含有量は、良好な吸水特性（加圧下における吸水特性等）が得られやすい観点から、０．０１ミリモル以上、０．０５ミリモル以上、０．０８ミリモル以上、０．１ミリモル以上、０．１５ミリモル以上、又は、０．２ミリモル以上が好ましい。内部架橋剤の含有量は、良好な吸水特性（加圧下における吸水特性等）が得られやすい観点から、１０ミリモル以下、８ミリモル以下、５ミリモル以下、３ミリモル以下、又は、２ミリモル以下が好ましい。これらの観点から、内部架橋剤の含有量は、０．０１～１０ミリモルが好ましい。 The content of the internal cross-linking agent is preferably in the following range with respect to 1 mol of the (meth) acrylic acid compound. The content of the internal cross-linking agent is 0.01 mmol or more, 0.05 mmol or more, 0.08 mmol or more, 0.1 mmol or more from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained. , 0.15 mmol or more, or 0.2 mmol or more is preferable. The content of the internal cross-linking agent is preferably 10 mmol or less, 8 mmol or less, 5 mmol or less, 3 mmol or less, or 2 mmol or less from the viewpoint that good water absorption characteristics (water absorption characteristics under pressure, etc.) can be easily obtained. .. From these viewpoints, the content of the internal cross-linking agent is preferably 0.01 to 10 mmol.
　単量体組成物は、必要に応じて、上述の各成分とは異なる成分として、連鎖移動剤、増粘剤、無機フィラー等の添加剤を含有してよい。連鎖移動剤としては、チオール類、チオール酸類、第２級アルコール類、次亜リン酸、亜リン酸、アクロレイン等が挙げられる。増粘剤としては、カルボキシメチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、メチルセルロース、ポリエチレングリコール、ポリアクリル酸、ポリアクリル酸中和物、ポリアクリルアミド等が挙げられる。無機フィラーとしては、金属酸化物、セラミック、粘度鉱物等が挙げられる。 If necessary, the monomer composition may contain additives such as a chain transfer agent, a thickener, and an inorganic filler as components different from the above-mentioned components. Examples of the chain transfer agent include thiols, thiol acids, secondary alcohols, hypophosphorous acid, phosphorous acid, achlorine and the like. Examples of the thickener include carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polyethylene glycol, polyacrylic acid, neutralized polyacrylic acid, polyacrylamide and the like. Examples of the inorganic filler include metal oxides, ceramics, and viscous minerals.
　水溶液重合の重合方式としては、単量体組成物を撹拌しない状態（例えば、静置状態）で重合する静置重合方式；反応装置内で単量体組成物を撹拌しながら重合する撹拌重合方式等が挙げられる。静置重合方式では、重合完了時、反応容器中に存在した単量体組成物と略同じ体積を占める単一のブロック状のゲルが得られる。 As a polymerization method for aqueous solution polymerization, a static polymerization method in which the monomer composition is polymerized without stirring (for example, a static state); a stirring polymerization method in which the monomer composition is polymerized while stirring in a reaction apparatus. And so on. In the static polymerization method, when the polymerization is completed, a single block-shaped gel occupying substantially the same volume as the monomer composition present in the reaction vessel is obtained.
　重合の形態は、回分、半連続、連続等であってよい。例えば、静置重合方式を連続重合にて行う場合、連続重合装置に単量体組成物を連続的に供給しながら重合反応を行い、連続的にゲルを得ることができる。 The form of polymerization may be batch, semi-continuous, continuous, or the like. For example, when the static polymerization method is carried out by continuous polymerization, the polymerization reaction can be carried out while continuously supplying the monomer composition to the continuous polymerization apparatus to continuously obtain a gel.
　重合温度は、使用する重合開始剤によって異なるが、重合を迅速に進行させ、重合時間を短くすることにより生産性を高めると共に、重合熱を除去して円滑に反応を行いやすい観点から、０～１３０℃又は１０～１１０℃が好ましい。重合温度の最大値は、２５℃以上、３０℃以上、４０℃以上、５０℃以上、又は、６０℃以上であってよい。重合温度の最大値は、１１０℃以下、１０５℃以下、１００℃以下、又は、９５℃以下であってよい。これらの観点から、重合温度の最大値は、２５～１１０℃であってよい。重合時間は、使用する重合開始剤の種類及び量、反応温度等に応じて適宜設定されるが、１～２００分又は５～１００分が好ましい。 The polymerization temperature varies depending on the polymerization initiator used, but from the viewpoint of rapidly advancing the polymerization, increasing the productivity by shortening the polymerization time, removing the heat of polymerization, and facilitating the smooth reaction, 0 to 0 to It is preferably 130 ° C. or 10 to 110 ° C. The maximum value of the polymerization temperature may be 25 ° C. or higher, 30 ° C. or higher, 40 ° C. or higher, 50 ° C. or higher, or 60 ° C. or higher. The maximum value of the polymerization temperature may be 110 ° C. or lower, 105 ° C. or lower, 100 ° C. or lower, or 95 ° C. or lower. From these viewpoints, the maximum value of the polymerization temperature may be 25 to 110 ° C. The polymerization time is appropriately set depending on the type and amount of the polymerization initiator used, the reaction temperature, and the like, but is preferably 1 to 200 minutes or 5 to 100 minutes.
　本実施形態に係る吸水性樹脂粒子の製造方法は、重合工程で得られた架橋重合体ゲルを粗砕して粗砕物（例えばゲル粗砕物）を得る粗砕工程と、粗砕物を乾燥して乾燥物を得る乾燥工程と、乾燥物を粉砕して粉砕物を得る粉砕工程と、を備えてよい。これらの乾燥物又は粉砕物は、篩Ｓ１又は篩Ｓ２を用いた分級の対象である重合体粒子群として用いることができる。 The method for producing the water-absorbent resin particles according to the present embodiment includes a rough crushing step of coarsely crushing the crosslinked polymer gel obtained in the polymerization step to obtain a coarse crushed product (for example, a gel coarse crushed product), and a drying of the coarse crushed product. A drying step of obtaining a dried product and a crushing step of crushing the dried product to obtain a crushed product may be provided. These dried products or pulverized products can be used as a polymer particle group to be classified using a sieve S1 or a sieve S2.
　粗砕工程における粗砕装置としては、例えば、ニーダー（加圧式ニーダー、双腕型ニーダー等）、ミートチョッパー、カッターミル、ファーマミル等を用いることができる。 As the crushing device in the crushing step, for example, a kneader (pressurized kneader, double-armed kneader, etc.), a meat chopper, a cutter mill, a pharma mill, or the like can be used.
　乾燥工程では、粗砕物中の液体成分（水等）を加熱及び／又は送風により除去することで乾燥物（例えばゲル乾燥物）を得ることができる。乾燥方法は、自然乾燥、加熱乾燥、送風乾燥、減圧乾燥等であってよい。乾燥温度は、例えば７０～２５０℃である。 In the drying step, a dried product (for example, gel dried product) can be obtained by removing liquid components (water, etc.) in the pyroclastic material by heating and / or blowing air. The drying method may be natural drying, heat drying, blast drying, vacuum drying or the like. The drying temperature is, for example, 70 to 250 ° C.
　粉砕工程における粉砕機としては、ローラーミル（ロールミル）、スタンプミル、ジェットミル、高速回転粉砕機（ハンマーミル、ピンミル、ロータビータミル等）、容器駆動型ミル（回転ミル、振動ミル、遊星ミル等）などが挙げられる。 Crushers in the crushing process include roller mills (roll mills), stamp mills, jet mills, high-speed rotary crushers (hammer mills, pin mills, rotor beater mills, etc.), container-driven mills (rotary mills, vibration mills, planetary mills, etc.). ) And so on.
　本実施形態に係る吸水性樹脂粒子は、本実施形態に係る吸水性樹脂粒子の製造方法により得られる。本実施形態に係る吸水性樹脂粒子は、加圧下における優れた吸水特性を得やすい観点から、エチレン性不飽和単量体に由来する構造単位を有することが好ましい。本実施形態に係る吸水性樹脂粒子は、エチレン性不飽和単量体を含有する単量体を重合させて得られる架橋重合体（エチレン性不飽和単量体に由来する構造単位を有する架橋重合体）を含むことが好ましい。エチレン性不飽和単量体としては、重合工程における単量体組成物に関する上述のエチレン性不飽和単量体を用いることができる。エチレン性不飽和単量体は、加圧下における優れた吸水特性を得やすい観点から、（メタ）アクリル酸及びその塩からなる群より選ばれる少なくとも１種の化合物を含むことが好ましい。 The water-absorbent resin particles according to the present embodiment can be obtained by the method for producing the water-absorbent resin particles according to the present embodiment. The water-absorbent resin particles according to the present embodiment preferably have a structural unit derived from an ethylenically unsaturated monomer from the viewpoint of easily obtaining excellent water-absorbing properties under pressure. The water-absorbent resin particles according to the present embodiment are crosslinked polymers (crosslinked weights having structural units derived from ethylenically unsaturated monomers) obtained by polymerizing a monomer containing an ethylenically unsaturated monomer. It is preferable to include coalescence). As the ethylenically unsaturated monomer, the above-mentioned ethylenically unsaturated monomer related to the monomer composition in the polymerization step can be used. The ethylenically unsaturated monomer preferably contains at least one compound selected from the group consisting of (meth) acrylic acid and a salt thereof from the viewpoint of easily obtaining excellent water absorption characteristics under pressure.
　本実施形態に係る吸水性樹脂粒子の形状としては、略球状、破砕状、顆粒状等が挙げられる。本実施形態に係る吸水性樹脂粒子は、水を保水可能であればよく、吸液対象の液は水を含むことができる。本実施形態に係る吸水性樹脂粒子は、尿、汗、血液（例えば経血）等の体液を吸液できる。本実施形態に係る吸水性樹脂粒子は、吸収体の構成成分として用いることができる。本実施形態は、例えば、紙おむつ、生理用品等の衛生材料；保水剤、土壌改良剤等の農園芸材料；止水剤、結露防止剤等の工業資材などの分野において用いることができる。 Examples of the shape of the water-absorbent resin particles according to the present embodiment include substantially spherical, crushed, and granular shapes. The water-absorbent resin particles according to the present embodiment may be any water-absorbent resin particles as long as they can retain water, and the liquid to be absorbed may contain water. The water-absorbent resin particles according to the present embodiment can absorb body fluids such as urine, sweat, and blood (for example, menstrual blood). The water-absorbent resin particles according to the present embodiment can be used as a constituent component of the absorber. This embodiment can be used in the fields of, for example, sanitary materials such as disposable diapers and sanitary products; agricultural and horticultural materials such as water retention agents and soil conditioners; and industrial materials such as water stop agents and dew condensation inhibitors.
　本実施形態に係る吸水性樹脂粒子は、ゲル安定剤；金属キレート剤（エチレンジアミン４酢酸及びその塩、ジエチレントリアミン５酢酸及びその塩（例えばジエチレントリアミン５酢酸５ナトリウム）等）；流動性向上剤（滑剤）などの他成分を更に含んでよい。他成分は、エチレン性不飽和単量体に由来する構造単位を有する架橋重合体の内部、表面上、又は、これらの両方に配置され得る。 The water-absorbent resin particles according to the present embodiment are gel stabilizers; metal chelating agents (ethylenediaminetetraacetic acid and salts thereof, diethylenetriamine-5 acetic acid and salts thereof (for example, diethylenetriamine-5sodium acetate), etc.); fluidity improvers (lubricant). Other components such as may be further contained. Other components may be located inside, on the surface, or both of crosslinked polymers having structural units derived from ethylenically unsaturated monomers.
　本実施形態に係る吸水性樹脂粒子は、エチレン性不飽和単量体に由来する構造単位を有する架橋重合体の表面上に配置された無機粒子を含んでよい。例えば、架橋重合体と無機粒子とを混合することにより、架橋重合体の表面上に無機粒子を配置することができる。無機粒子としては、例えば、非晶質シリカ等のシリカ粒子が挙げられる。 The water-absorbent resin particles according to the present embodiment may contain inorganic particles arranged on the surface of a crosslinked polymer having a structural unit derived from an ethylenically unsaturated monomer. For example, by mixing the crosslinked polymer and the inorganic particles, the inorganic particles can be arranged on the surface of the crosslinked polymer. Examples of the inorganic particles include silica particles such as amorphous silica.
　本実施形態に係る吸水性樹脂粒子のＣＲＣは、下記の範囲が好ましい。ＣＲＣは、２０ｇ／ｇ以上が好ましく、２５ｇ／ｇ以上がより好ましく、３０ｇ／ｇ以上が更に好ましく、３１ｇ／ｇ以上が特に好ましく、３２ｇ／ｇ以上が極めて好ましく、３３ｇ／ｇ以上が非常に好ましく、３５ｇ／ｇ以上がより一層好ましく、３８ｇ／ｇ以上が更に好ましく、４０ｇ／ｇ以上が特に好ましく、４５ｇ／ｇ以上が極めて好ましい。ＣＲＣは、６０ｇ／ｇ以下が好ましく、５５ｇ／ｇ以下がより好ましく、５０ｇ／ｇ以下が更に好ましく、４６ｇ／ｇ以下が特に好ましい。これらの観点から、ＣＲＣは、２０～６０ｇ／ｇが好ましく、２０～５５ｇ／ｇがより好ましく、３０～５０ｇ／ｇが更に好ましい。 The CRC of the water-absorbent resin particles according to this embodiment is preferably in the following range. The CRC is preferably 20 g / g or more, more preferably 25 g / g or more, further preferably 30 g / g or more, particularly preferably 31 g / g or more, extremely preferably 32 g / g or more, and very preferably 33 g / g or more. , 35 g / g or more is even more preferable, 38 g / g or more is further preferable, 40 g / g or more is particularly preferable, and 45 g / g or more is extremely preferable. The CRC is preferably 60 g / g or less, more preferably 55 g / g or less, further preferably 50 g / g or less, and particularly preferably 46 g / g or less. From these viewpoints, the CRC is preferably 20 to 60 g / g, more preferably 20 to 55 g / g, and even more preferably 30 to 50 g / g.
　本実施形態に係る吸水性樹脂粒子の４．８３ｋＰａ加圧下の吸収倍率（ＡＡＰ）は、８．３ｇ／ｇ以上が好ましく、８．５ｇ／ｇ以上がより好ましく、９．０ｇ／ｇ以上が更に好ましく、１０．０ｇ／ｇ以上が特に好ましく、１５．０ｇ／ｇ以上が極めて好ましく、１６．０ｇ／ｇ以上が非常に好ましく、１７．０ｇ／ｇ以上がより一層好ましく、１８．０ｇ／ｇ以上が更に好ましい。吸水性樹脂粒子の４．８３ｋＰａ加圧下の吸収倍率（ＡＡＰ）の上限は、例えば、４０．０ｇ／ｇ以下、３５．０ｇ／ｇ以下、３０．０ｇ／ｇ以下、２５．０ｇ／ｇ以下、又は、２０．０ｇ／ｇ以下であってよい。 The absorption ratio (AAP) of the water-absorbent resin particles according to the present embodiment under pressurization of 4.83 kPa is preferably 8.3 g / g or more, more preferably 8.5 g / g or more, and further preferably 9.0 g / g or more. Preferably, 10.0 g / g or more is particularly preferable, 15.0 g / g or more is extremely preferable, 16.0 g / g or more is very preferable, 17.0 g / g or more is even more preferable, and 18.0 g / g or more is preferable. Is more preferable. The upper limit of the absorption ratio (AAP) of the water-absorbent resin particles under pressure of 4.83 kPa is, for example, 40.0 g / g or less, 35.0 g / g or less, 30.0 g / g or less, 25.0 g / g or less, Alternatively, it may be 20.0 g / g or less.
　本実施形態に係る吸収体は、本実施形態に係る吸水性樹脂粒子を含有する。本実施形態に係る吸収体は、繊維状物を含有していてもよく、例えば、吸水性樹脂粒子及び繊維状物を含む混合物である。吸収体の構成としては、例えば、吸水性樹脂粒子及び繊維状物が均一混合された構成であってよく、シート状又は層状に形成された繊維状物の間に吸水性樹脂粒子が挟まれた構成であってもよく、その他の構成であってもよい。 The absorber according to the present embodiment contains the water-absorbent resin particles according to the present embodiment. The absorber according to the present embodiment may contain a fibrous substance, for example, a mixture containing water-absorbent resin particles and the fibrous substance. The structure of the absorber may be, for example, a structure in which the water-absorbent resin particles and the fibrous material are uniformly mixed, and the water-absorbent resin particles are sandwiched between the fibrous material formed in a sheet or layer. It may be a configuration or another configuration.
　繊維状物としては、微粉砕された木材パルプ；コットン；コットンリンター；レーヨン；セルロースアセテート等のセルロース系繊維；ポリアミド、ポリエステル、ポリオレフィン等の合成繊維；これらの繊維の混合物などが挙げられる。繊維状物は、１種単独で用いられてもよく、２種以上を組み合わせて用いられてもよい。繊維状物としては、親水性繊維を用いることができる。 Examples of the fibrous material include finely pulverized wood pulp; cotton; cotton linter; rayon; cellulosic fibers such as cellulose acetate; synthetic fibers such as polyamide, polyester and polyolefin; and a mixture of these fibers. The fibrous material may be used alone or in combination of two or more. As the fibrous material, hydrophilic fibers can be used.
　吸収体における吸水性樹脂粒子の質量割合は、吸水性樹脂粒子及び繊維状物の合計に対して、２～１００質量％、１０～８０質量％又は２０～６０質量％であってよい。 The mass ratio of the water-absorbent resin particles in the absorber may be 2 to 100% by mass, 10 to 80% by mass, or 20 to 60% by mass with respect to the total of the water-absorbent resin particles and the fibrous material.
　吸収体における吸水性樹脂粒子の含有量は、充分な吸水特性を得やすい観点から、吸収体１ｍ２当たり、１００～１０００ｇが好ましく、１５０～８００ｇがより好ましく、２００～７００ｇが更に好ましい。吸収体における繊維状物の含有量は、充分な吸水特性を得やすい観点から、吸収体１ｍ２あたり、５０～８００ｇが好ましく、１００～６００ｇがより好ましく、１５０～５００ｇが更に好ましい。 The content of the water-absorbent resin particles in the absorber is preferably 100 to 1000 g, more preferably 150 to 800 g, and even more preferably 200 to 700 g per 1 m 2 of the absorber from the viewpoint of easily obtaining sufficient water absorption characteristics. The content of the fibrous substance in the absorber is preferably 50 to 800 g, more preferably 100 to 600 g, and even more preferably 150 to 500 g per 1 m 2 of the absorber from the viewpoint of easily obtaining sufficient water absorption characteristics.
　吸収体の使用前及び使用中における形態保持性を高めるために、繊維状物に接着性バインダーを添加することによって繊維同士を接着させてもよい。接着性バインダーとしては、熱融着性合成繊維、ホットメルト接着剤、接着性エマルジョン等が挙げられる。接着性バインダーは、１種単独で用いられてもよく、２種以上を組み合わせて用いられてもよい。 In order to improve the shape retention before and during use of the absorber, the fibers may be adhered to each other by adding an adhesive binder to the fibrous material. Examples of the adhesive binder include heat-sealing synthetic fibers, hot melt adhesives, and adhesive emulsions. The adhesive binder may be used alone or in combination of two or more.
　熱融着性合成繊維としては、ポリエチレン、ポリプロピレン、エチレン－プロピレン共重合体等の全融型バインダー；ポリプロピレンとポリエチレンとのサイドバイサイド又は芯鞘構造からなる非全融型バインダーなどが挙げられる。上述の非全融型バインダーにおいては、ポリエチレン部分のみ熱融着することができる。 Examples of the heat-bondable synthetic fiber include a total fusion type binder such as polyethylene, polypropylene, and an ethylene-propylene copolymer; a non-total fusion type binder having a side-by-side or core-sheath structure of polypropylene and polyethylene. In the above-mentioned non-total fusion type binder, only the polyethylene portion can be heat-sealed.
　ホットメルト接着剤としては、例えば、エチレン－酢酸ビニルコポリマー、スチレン－イソプレン－スチレンブロックコポリマー、スチレン－ブタジエン－スチレンブロックコポリマー、スチレン－エチレン－ブチレン－スチレンブロックコポリマー、スチレン－エチレン－プロピレン－スチレンブロックコポリマー、アモルファスポリプロピレン等のベースポリマーと、粘着付与剤、可塑剤、酸化防止剤等との混合物が挙げられる。 Examples of hot melt adhesives include ethylene-vinyl acetate copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, and styrene-ethylene-propylene-styrene block copolymer. , A mixture of a base polymer such as amorphous polypropylene and a tackifier, a plasticizer, an antioxidant and the like.
　接着性エマルジョンとしては、例えば、メチルメタクリレート、スチレン、アクリロニトリル、２ーエチルヘキシルアクリレート、ブチルアクリレート、ブタジエン、エチレン、及び、酢酸ビニルからなる群より選ばれる少なくとも一種の単量体の重合物が挙げられる。 Examples of the adhesive emulsion include polymers of at least one monomer selected from the group consisting of methyl methacrylate, styrene, acrylonitrile, 2-ethylhexyl acrylate, butyl acrylate, butadiene, ethylene, and vinyl acetate.
　本実施形態に係る吸収体は、無機粉末（例えば非晶質シリカ）、消臭剤、抗菌剤、香料等を含有してもよい。吸水性樹脂粒子が無機粒子を含む場合、吸収体は、吸水性樹脂粒子中の無機粒子とは別に無機粉末を含有してよい。 The absorber according to the present embodiment may contain an inorganic powder (for example, amorphous silica), a deodorant, an antibacterial agent, a fragrance, and the like. When the water-absorbent resin particles contain inorganic particles, the absorber may contain inorganic powder in addition to the inorganic particles in the water-absorbent resin particles.
　本実施形態に係る吸収体の形状は、例えばシート状であってよい。吸収体の厚さ（例えば、シート状の吸収体の厚さ）は、例えば０．１～２０ｍｍ、０．３～１５ｍｍであってよい。 The shape of the absorber according to the present embodiment may be, for example, a sheet shape. The thickness of the absorber (for example, the thickness of the sheet-shaped absorber) may be, for example, 0.1 to 20 mm and 0.3 to 15 mm.
　本実施形態に係る吸収性物品は、本実施形態に係る吸収体を備える。本実施形態に係る吸収性物品は、吸収体を保形するコアラップ；吸液対象の液が浸入する側の最外部に配置される液体透過性シート；吸液対象の液が浸入する側とは反対側の最外部に配置される液体不透過性シート等が挙げられる。吸収性物品としては、おむつ（例えば紙おむつ）、トイレトレーニングパンツ、失禁パッド、衛生材料（生理用ナプキン、タンポン等）、汗取りパッド、ペットシート、簡易トイレ用部材、動物***物処理材などが挙げられる。 The absorbent article according to the present embodiment includes an absorber according to the present embodiment. The absorbent article according to the present embodiment is a core wrap that retains the shape of the absorber; a liquid permeable sheet that is arranged on the outermost side of the side where the liquid to be absorbed enters; Examples thereof include a liquid permeable sheet arranged on the outermost side on the opposite side. Examples of absorbent articles include diapers (for example, paper diapers), toilet training pants, incontinence pads, sanitary materials (sanitary napkins, tampons, etc.), sweat pads, pet sheets, simple toilet materials, animal excrement treatment materials, and the like. ..
　図１は、吸収性物品の一例を示す断面図である。図１に示す吸収性物品１００は、吸収体１０と、コアラップ２０ａ，２０ｂと、液体透過性シート３０と、液体不透過性シート４０と、を備える。吸収性物品１００において、液体不透過性シート４０、コアラップ２０ｂ、吸収体１０、コアラップ２０ａ、及び、液体透過性シート３０がこの順に積層している。図１において、部材間に間隙があるように図示されている部分があるが、当該間隙が存在することなく部材間が密着していてよい。 FIG. 1 is a cross-sectional view showing an example of an absorbent article. The absorbent article 100 shown in FIG. 1 includes an absorber 10, core wraps 20a and 20b, a liquid permeable sheet 30, and a liquid permeable sheet 40. In the absorbent article 100, the liquid permeable sheet 40, the core wrap 20b, the absorbent body 10, the core wrap 20a, and the liquid permeable sheet 30 are laminated in this order. In FIG. 1, there is a portion shown so that there is a gap between the members, but the members may be in close contact with each other without the gap.
　吸収体１０は、本実施形態に係る吸水性樹脂粒子１０ａと、繊維状物を含む繊維層１０ｂと、を有する。吸水性樹脂粒子１０ａは、繊維層１０ｂ内に分散している。 The absorber 10 has a water-absorbent resin particle 10a according to the present embodiment and a fiber layer 10b containing a fibrous material. The water-absorbent resin particles 10a are dispersed in the fiber layer 10b.
　コアラップ２０ａは、吸収体１０に接した状態で吸収体１０の一方面側（図１中、吸収体１０の上側）に配置されている。コアラップ２０ｂは、吸収体１０に接した状態で吸収体１０の他方面側（図１中、吸収体１０の下側）に配置されている。吸収体１０は、コアラップ２０ａとコアラップ２０ｂとの間に配置されている。コアラップ２０ａ，２０ｂとしては、ティッシュ、不織布等が挙げられる。コアラップ２０ａ及びコアラップ２０ｂは、例えば、吸収体１０と同等の大きさの主面を有している。 The core wrap 20a is arranged on one side of the absorber 10 (upper side of the absorber 10 in FIG. 1) in contact with the absorber 10. The core wrap 20b is arranged on the other side of the absorber 10 (lower side of the absorber 10 in FIG. 1) in contact with the absorber 10. The absorber 10 is arranged between the core wrap 20a and the core wrap 20b. Examples of the core wraps 20a and 20b include tissues, non-woven fabrics and the like. The core wrap 20a and the core wrap 20b have, for example, a main surface having the same size as the absorber 10.
　液体透過性シート３０は、吸収対象の液が浸入する側の最外部に配置されている。液体透過性シート３０は、コアラップ２０ａに接した状態でコアラップ２０ａ上に配置されている。液体透過性シート３０としては、ポリエチレン、ポリプロピレン、ポリエステル、ポリアミド等の合成樹脂からなる不織布、多孔質シートなどが挙げられる。液体不透過性シート４０は、吸収性物品１００において液体透過性シート３０とは反対側の最外部に配置されている。液体不透過性シート４０は、コアラップ２０ｂに接した状態でコアラップ２０ｂの下側に配置されている。液体不透過性シート４０としては、ポリエチレン、ポリプロピレン、ポリ塩化ビニル等の合成樹脂からなるシート、これらの合成樹脂と不織布との複合材料からなるシートなどが挙げられる。液体透過性シート３０及び液体不透過性シート４０は、例えば、吸収体１０の主面よりも広い主面を有しており、液体透過性シート３０及び液体不透過性シート４０の外縁部は、吸収体１０及びコアラップ２０ａ，２０ｂの周囲に延在している。 The liquid permeable sheet 30 is arranged on the outermost side on the side where the liquid to be absorbed enters. The liquid permeable sheet 30 is arranged on the core wrap 20a in contact with the core wrap 20a. Examples of the liquid permeable sheet 30 include non-woven fabrics made of synthetic resins such as polyethylene, polypropylene, polyester and polyamide, and porous sheets. The liquid permeable sheet 40 is arranged on the outermost side of the absorbent article 100 on the opposite side of the liquid permeable sheet 30. The liquid impermeable sheet 40 is arranged under the core wrap 20b in contact with the core wrap 20b. Examples of the liquid impermeable sheet 40 include a sheet made of a synthetic resin such as polyethylene, polypropylene, and polyvinyl chloride, and a sheet made of a composite material of these synthetic resins and a non-woven fabric. The liquid permeable sheet 30 and the liquid permeable sheet 40 have, for example, a main surface wider than the main surface of the absorber 10, and the outer edges of the liquid permeable sheet 30 and the liquid permeable sheet 40 are It extends around the absorber 10 and the core wraps 20a, 20b.
　吸収体１０、コアラップ２０ａ，２０ｂ、液体透過性シート３０、及び、液体不透過性シート４０の大小関係は、特に限定されず、吸収性物品の用途等に応じて適宜調整される。また、コアラップ２０ａ，２０ｂを用いて吸収体１０を保形する方法は、特に限定されず、図１に示すように複数のコアラップにより吸収体を包んでよく、１枚のコアラップにより吸収体を包んでもよい。 The magnitude relationship between the absorbent body 10, the core wraps 20a and 20b, the liquid permeable sheet 30, and the liquid permeable sheet 40 is not particularly limited, and is appropriately adjusted according to the use of the absorbent article and the like. Further, the method of retaining the shape of the absorber 10 using the core wraps 20a and 20b is not particularly limited, and as shown in FIG. 1, the absorber may be wrapped by a plurality of core wraps, and the absorber is wrapped by one core wrap. But it may be.
　本実施形態によれば、本実施形態に係る吸水性樹脂粒子、吸収体又は吸収性物品を用いた吸液方法を提供することができる。本実施形態に係る吸液方法は、本実施形態に係る吸水性樹脂粒子、吸収体又は吸収性物品に吸液対象の液を接触させる工程を備える。本実施形態によれば、吸液への樹脂粒子、吸収体及び吸収性物品の応用を提供することができる。 According to the present embodiment, it is possible to provide a liquid absorbing method using the water-absorbent resin particles, the absorbent body or the absorbent article according to the present embodiment. The liquid absorbing method according to the present embodiment includes a step of bringing the liquid to be absorbed into contact with the water-absorbent resin particles, the absorber or the absorbent article according to the present embodiment. According to this embodiment, it is possible to provide application of resin particles, an absorber and an absorbent article to a liquid absorbent.
　以下、実験例を用いて本発明の内容を更に詳細に説明するが、本発明は以下の実験例に限定されるものではない。以下において実験操作時の温度を記載していない場合には、室温において当該実験操作を行うことができる。 Hereinafter, the content of the present invention will be described in more detail using experimental examples, but the present invention is not limited to the following experimental examples. If the temperature at the time of the experimental operation is not described below, the experimental operation can be performed at room temperature.
＜未表面架橋の重合体粒子の作製＞
（アクリル酸部分中和液の調製）
　攪拌機を備えた内径１１ｃｍ、内容積２Ｌの丸底円筒型セパラブルフラスコに５００ｇ（６．９４モル）の１００％アクリル酸を入れた。このアクリル酸を撹拌しながらセパラブルフラスコ内にイオン交換水４２８．２７ｇを加えた後、氷浴下で４３９．４１ｇの４８質量％水酸化ナトリウムを滴下することにより、単量体濃度４５．０４質量％のアクリル酸部分中和液（中和率７５．９３モル％）１３６７．６８ｇを調製した。本操作を５回繰り返し、後述の重合に用いた。 <Preparation of unsurface-crosslinked polymer particles>
(Preparation of partial neutralization solution of acrylic acid)
500 g (6.94 mol) of 100% acrylic acid was placed in a round bottom cylindrical separable flask having an inner diameter of 11 cm and an internal volume of 2 L equipped with a stirrer. After adding 428.27 g of ion-exchanged water into the separable flask while stirring this acrylic acid, 439.41 g of 48% by mass sodium hydroxide was added dropwise under an ice bath to give a monomer concentration of 45.04. 1376.68 g of a mass% acrylic acid partial neutralizing solution (neutralization rate 75.93 mol%) was prepared. This operation was repeated 5 times and used for the polymerization described later.
（製造例Ｉ）
　単量体濃度４５．０４質量％のアクリル酸部分中和液（中和率７５．９３モル％）２３２０．１６ｇにイオン交換水３３７．１３ｇ及びポリエチレングリコールジアクリレート（ｎ＝９）２．４２ｇを加えて反応液（単量体水溶液）を得た。次に、この反応液を窒素ガス雰囲気下で３０分間脱気した。次いで、開閉可能な蓋付きのシグマ型羽根を２本有するジャケット付きステンレス製双腕型ニーダーに上記反応液を供給し、反応液を３０℃に保ちながら反応系を窒素ガス置換した。続いて、反応液を撹拌しながら、２．０質量％の過硫酸ナトリウム水溶液７７．１０ｇ及び０．５質量％のＬ－アスコルビン酸水溶液１３．１９ｇを加えたところ、凡そ１分後に重合が開始した。そして、３０～９０℃で重合を行い、重合を開始して６０分後に含水ゲルを取り出した。 (Manufacturing Example I)
337.13 g of ion-exchanged water and 2.42 g of polyethylene glycol diacrylate (n = 9) were added to 2320.16 g of a partially neutralized acrylic acid solution (neutralization rate 75.93 mol%) having a monomer concentration of 45.04% by mass. In addition, a reaction solution (monomer aqueous solution) was obtained. Next, the reaction solution was degassed in a nitrogen gas atmosphere for 30 minutes. Next, the reaction solution was supplied to a stainless steel double-armed kneader with a jacket having two sigma-type blades with openable and closable lids, and the reaction system was replaced with nitrogen gas while keeping the reaction solution at 30 ° C. Subsequently, 77.10 g of a 2.0 mass% sodium persulfate aqueous solution and 13.19 g of a 0.5 mass% L-ascorbic acid aqueous solution were added while stirring the reaction solution, and the polymerization started after about 1 minute. did. Then, the polymerization was carried out at 30 to 90 ° C., and 60 minutes after the start of the polymerization, the hydrogel was taken out.
　得られた含水ゲルを喜連ローヤル株式会社製のミートチョッパー１２ＶＲ－７５０ＳＤＸに順次投入して細分化した。ミートチョッパーの尖端に位置するプレートの穴の径は６．４ｍｍであった。この細分化された粒子状含水ゲルを目開き０．８ｃｍ×０．８ｃｍの金網上に広げて配置した後、１６０℃で６０分間熱風乾燥して乾燥物を得た。 The obtained hydrogel was sequentially put into a meat chopper 12VR-750SDX manufactured by Kiren Royal Co., Ltd. and subdivided. The diameter of the hole in the plate located at the tip of the meat chopper was 6.4 mm. This subdivided particulate hydrogel was spread and placed on a wire mesh having an opening of 0.8 cm × 0.8 cm, and then dried with hot air at 160 ° C. for 60 minutes to obtain a dried product.
　以上の操作を合計３回繰り返すことにより、以下の実験に充分な量の乾燥物を得た。 By repeating the above operation a total of 3 times, a sufficient amount of dried product was obtained for the following experiments.
　次いで、遠心粉砕機（Ｒｅｔｓｃｈ社製、ＺＭ２００、スクリーン口径１ｍｍ、６０００ｒｐｍ）を用いて乾燥物を粉砕し、目開き８５０μｍの篩を通過させた不定形破砕状の重合体粒子（α）（乾燥減量：１．８質量％）を得た。このとき、重合体粒子（α）のＣＲＣは３９ｇ／ｇであり、中位粒子径は３５２μｍであり、「０μｍを超え１８０μｍ未満」の粒子径範囲の質量割合（目開き１８０μｍの篩を通過した分画である重合体粒子の割合）は３０質量％であった。さらに、不定形破砕状の重合体粒子（α）を目開き１８０μｍの篩で分級することにより、目開き１８０μｍの篩を通過しなかった分画（篩上に残存した分画。表１中、「１８０μｍ　оｎ」、以下同様）である重合体粒子（Ａ１－１）、及び、目開き１８０μｍの篩を通過した分画（表１中、「１８０μｍ　ｐａｓｓ」、以下同様）である重合体粒子（Ｂ１－１）を得た。 Next, the dried product was crushed using a centrifugal crusher (Resch, ZM200, screen diameter 1 mm, 6000 rpm), and the amorphous crushed polymer particles (α) (dry weight loss) were passed through a sieve having an opening of 850 μm. 1.8% by mass) was obtained. At this time, the CRC of the polymer particles (α) was 39 g / g, the medium particle size was 352 μm, and the mass ratio in the particle size range of “more than 0 μm and less than 180 μm” (passed through a sieve having an opening of 180 μm). The proportion of polymer particles as a fraction) was 30% by mass. Further, by classifying the amorphous crushed polymer particles (α) with a sieve having a mesh size of 180 μm, a fraction that did not pass through the sieve having a mesh size of 180 μm (fraction remaining on the sieve. In Table 1, Polymer particles (A1-1) which are "180 μm оn", the same applies hereinafter) and polymer particles (A1-1) which are fractions (in Table 1, "180 μm pass", the same applies hereinafter) which have passed through a sieve having a mesh size of 180 μm. B1-1) was obtained.
（製造例ＩＩ）
　単量体濃度４５．０４質量％のアクリル酸部分中和液（中和率７５．９３モル％）２７８４．１９ｇにイオン交換水４０６．４９ｇ及びポリエチレングリコールジアクリレート（ｎ＝９）０．９７ｇを加えて反応液（単量体水溶液）を得た。次に、この反応液を窒素ガス雰囲気下で３０分間脱気した。次いで、開閉可能な蓋付きのシグマ型羽根を２本有するジャケット付きステンレス製双腕型ニーダーに上記反応液を供給し、反応液を３０℃に保ちながら反応系を窒素ガス置換した。続いて、反応液を撹拌しながら、２．０質量％の過硫酸ナトリウム水溶液９２．５２ｇ及び０．５質量％のＬ－アスコルビン酸水溶液１５．８３ｇを加えたところ、凡そ１分後に重合が開始した。そして、３０～９０℃で重合を行い、重合を開始して６０分後に含水ゲルを取り出した。 (Production Example II)
406.49 g of ion-exchanged water and 0.97 g of polyethylene glycol diacrylate (n = 9) were added to 2784.19 g of a partially neutralized acrylic acid solution (neutralization rate 75.93 mol%) having a monomer concentration of 45.04% by mass. In addition, a reaction solution (monomer aqueous solution) was obtained. Next, the reaction solution was degassed in a nitrogen gas atmosphere for 30 minutes. Next, the reaction solution was supplied to a stainless steel double-armed kneader with a jacket having two sigma-type blades with openable and closable lids, and the reaction system was replaced with nitrogen gas while keeping the reaction solution at 30 ° C. Subsequently, while stirring the reaction solution, 92.52 g of a 2.0 mass% sodium persulfate aqueous solution and 15.83 g of a 0.5 mass% L-ascorbic acid aqueous solution were added, and the polymerization started after about 1 minute. did. Then, the polymerization was carried out at 30 to 90 ° C., and 60 minutes after the start of the polymerization, the hydrogel was taken out.
　得られた含水ゲルを喜連ローヤル株式会社製のミートチョッパー１２ＶＲ－７５０ＳＤＸに順次投入して細分化した。ミートチョッパーの尖端に位置するプレートの穴の径は６．４ｍｍであった。この細分化された粒子状含水ゲルを目開き０．８ｃｍ×０．８ｃｍの金網上に広げて配置した後、１６０℃で６０分間熱風乾燥して乾燥物を得た。 The obtained hydrogel was sequentially put into a meat chopper 12VR-750SDX manufactured by Kiren Royal Co., Ltd. and subdivided. The diameter of the hole in the plate located at the tip of the meat chopper was 6.4 mm. This subdivided particulate hydrogel was spread and placed on a wire mesh having an opening of 0.8 cm × 0.8 cm, and then dried with hot air at 160 ° C. for 60 minutes to obtain a dried product.
　次いで、遠心粉砕機（Ｒｅｔｓｃｈ社製、ＺＭ２００、スクリーン口径１ｍｍ、１２０００ｒｐｍ）を用いて乾燥物を粉砕し、目開き８５０μｍの篩を通過させた不定形破砕状の重合体粒子（β）（乾燥減量：１．２質量％）を得た。このとき、重合体粒子（β）のＣＲＣは５１ｇ／ｇであり、中位粒子径は２５４μｍであり、「０μｍを超え１８０μｍ未満」の粒子径範囲の質量割合（目開き１８０μｍの篩を通過した分画である重合体粒子の割合）は３５質量％であった。さらに、不定形破砕状の重合体粒子（β）を目開き１８０μｍの篩で分級することにより、目開き１８０μｍの篩を通過しなかった分画（篩上に残存した分画）である重合体粒子（Ａ１－２）、及び、目開き１８０μｍの篩を通過した分画である重合体粒子（Ｂ１－２）を得た。 Next, the dried product was crushed using a centrifugal crusher (Resch, ZM200, screen diameter 1 mm, 12000 rpm), and the amorphous crushed polymer particles (β) (dry weight loss) were passed through a sieve having an opening of 850 μm. : 1.2% by mass) was obtained. At this time, the CRC of the polymer particles (β) was 51 g / g, the medium particle size was 254 μm, and the mass ratio in the particle size range of “more than 0 μm and less than 180 μm” (passed through a sieve having an opening of 180 μm). The proportion of polymer particles as a fraction) was 35% by mass. Further, by classifying the amorphous crushed polymer particles (β) with a sieve having a mesh size of 180 μm, the polymer which is a fraction (fraction remaining on the sieve) that did not pass through the sieve having a mesh size of 180 μm. Particles (A1-2) and polymer particles (B1-2), which are fractions that passed through a sieve having a mesh size of 180 μm, were obtained.
（粒度分布）
　重合体粒子（α）及び重合体粒子（β）における「０μｍを超え１８０μｍ未満」の粒子径範囲の質量割合は次の手順で算出した。連続全自動音波振動式ふるい分け測定器（ロボットシフター　ＲＰＳ－２０５、株式会社セイシン企業製）を用いて、ＪＩＳ規格の目開き８５０μｍ、５００μｍ、４２５μｍ、３００μｍ、２５０μｍ、１８０μｍ及び１０６μｍの篩、並びに、受け皿で重合体粒子１０ｇの粒度分布を測定した。各篩上に残った粒子の質量を全量に対する質量百分率として算出し粒度分布を求めた。目開き１８０μｍの篩及び受け皿に残存した粒子の合計量に基づき「０μｍを超え１８０μｍ未満」の粒子径範囲の質量割合を算出した。 (Particle size distribution)
The mass ratio of the polymer particles (α) and the polymer particles (β) in the particle size range of “more than 0 μm and less than 180 μm” was calculated by the following procedure. Using a continuous fully automatic sonic vibration type sieving measuring instrument (Robot Shifter RPS-205, manufactured by Seishin Enterprise Co., Ltd.), JIS standard meshes of 850 μm, 500 μm, 425 μm, 300 μm, 250 μm, 180 μm and 106 μm, and a saucer. The particle size distribution of 10 g of the polymer particles was measured in. The mass of the particles remaining on each sieve was calculated as a mass percentage with respect to the total amount, and the particle size distribution was obtained. The mass ratio in the particle size range of "more than 0 μm and less than 180 μm" was calculated based on the total amount of particles remaining on the sieve and the saucer having a mesh size of 180 μm.
（中位粒子径）
　重合体粒子（α）及び重合体粒子（β）の中位粒子径は次の手順で算出した。上記の粒度分布に関して、篩上に残存した粒子の質量を粒子径の大きい方から順に積算することにより、篩の目開きと、篩上に残った粒子の質量百分率の積算値との関係を対数確率紙にプロットした。確率紙上のプロットを直線で結ぶことにより、積算質量百分率５０質量％に相当する粒子径を中位粒子径として得た。 (Medium particle size)
The medium particle diameters of the polymer particles (α) and the polymer particles (β) were calculated by the following procedure. With respect to the above particle size distribution, by integrating the masses of the particles remaining on the sieve in order from the one with the largest particle diameter, the relationship between the mesh size of the sieve and the integrated value of the mass percentage of the particles remaining on the sieve is logarithmic. Plotted on probability paper. By connecting the plots on the probability paper with a straight line, the particle size corresponding to the cumulative mass percentage of 50% by mass was obtained as the medium particle size.
＜表面架橋された重合体粒子の作製＞
（製造例１）
　重合体粒子（Ａ１－１）２５質量部に、エチレンカーボネート（ＥＣ）０．０７８３質量部、プロピレングリコール（ＰＧ）０．１２５質量部、及び、脱イオン水０．５質量部からなる表面架橋剤溶液を２２℃で混合して混合物を得た。この混合物を２００℃で３５分間加熱処理した後、目開き８５０μｍの篩で分級することにより、目開き８５０μｍの篩を通過した分画として、表面架橋された重合体粒子（Ａ２－１ａ）を得た。 <Preparation of surface-crosslinked polymer particles>
(Manufacturing Example 1)
A surface cross-linking agent consisting of 25 parts by mass of polymer particles (A1-1), 0.0783 parts by mass of ethylene carbonate (EC), 0.125 parts by mass of propylene glycol (PG), and 0.5 parts by mass of deionized water. The solution was mixed at 22 ° C. to give a mixture. This mixture is heat-treated at 200 ° C. for 35 minutes and then classified with a sieve having an opening of 850 μm to obtain surface-crosslinked polymer particles (A2-1a) as a fraction that has passed through a sieve having an opening of 850 μm. It was.
（製造例２）
　表面架橋剤溶液の混合温度を５℃に変更したこと以外は製造例１と同様に実施し、表面架橋された重合体粒子（Ａ２－１ｂ）を得た。 (Manufacturing Example 2)
The same procedure as in Production Example 1 was carried out except that the mixing temperature of the surface cross-linking agent solution was changed to 5 ° C. to obtain surface-crosslinked polymer particles (A2-1b).
（製造例３）
　プロピレングリコールの使用量を０．６２５質量部に変更したこと以外は製造例１と同様に実施し、表面架橋された重合体粒子（Ａ２－１ｃ）を得た。 (Manufacturing Example 3)
The same procedure as in Production Example 1 was carried out except that the amount of propylene glycol used was changed to 0.625 parts by mass to obtain surface-crosslinked polymer particles (A2-1c).
（製造例４）
　重合体粒子（Ａ１－１）を重合体粒子（Ａ１－２）に変更したこと以外は製造例１と同様に実施し、表面架橋された重合体粒子（Ａ２－２ａ）を得た。 (Manufacturing Example 4)
The same procedure as in Production Example 1 was carried out except that the polymer particles (A1-1) were changed to the polymer particles (A1-2) to obtain surface-crosslinked polymer particles (A2-2a).
（製造例５）
　重合体粒子（Ａ１－１）を重合体粒子（Ｂ１－１）に変更したこと以外は製造例１と同様に実施し、表面架橋された重合体粒子（Ｂ２－１ａ）を得た。 (Manufacturing Example 5)
The same procedure as in Production Example 1 was carried out except that the polymer particles (A1-1) were changed to the polymer particles (B1-1) to obtain surface-crosslinked polymer particles (B2-1a).
（製造例６）
　エチレンカーボネートの使用量を０．１５６６質量部に変更したこと以外は製造例５と同様に実施し、表面架橋された重合体粒子（Ｂ２－１ｂ）を得た。 (Manufacturing Example 6)
The same procedure as in Production Example 5 was carried out except that the amount of ethylene carbonate used was changed to 0.1566 parts by mass to obtain surface-crosslinked polymer particles (B2-1b).
（製造例７）
　エチレンカーボネートの使用量を０．２３４９質量部に変更したこと以外は製造例５と同様に実施し、表面架橋された重合体粒子（Ｂ２－１ｃ）を得た。 (Manufacturing Example 7)
The same procedure as in Production Example 5 was carried out except that the amount of ethylene carbonate used was changed to 0.2349 parts by mass to obtain surface-crosslinked polymer particles (B2-1c).
（製造例８）
　表面架橋剤溶液の混合温度を５℃に変更したこと以外は製造例５と同様に実施し、表面架橋された重合体粒子（Ｂ２－１ｄ）を得た。 (Manufacturing Example 8)
The same procedure as in Production Example 5 was carried out except that the mixing temperature of the surface cross-linking agent solution was changed to 5 ° C. to obtain surface-crosslinked polymer particles (B2-1d).
（製造例９）
　表面架橋剤溶液の混合温度を１５℃に変更したこと以外は製造例５と同様に実施し、表面架橋された重合体粒子（Ｂ２－１ｅ）を得た。 (Manufacturing Example 9)
The same procedure as in Production Example 5 was carried out except that the mixing temperature of the surface cross-linking agent solution was changed to 15 ° C. to obtain surface-crosslinked polymer particles (B2-1e).
（製造例１０）
　プロピレングリコールの使用量を０．２５０質量部に変更したこと以外は製造例５と同様に実施し、表面架橋された重合体粒子（Ｂ２－１ｆ）を得た。 (Manufacturing Example 10)
The same procedure as in Production Example 5 was carried out except that the amount of propylene glycol used was changed to 0.250 parts by mass to obtain surface-crosslinked polymer particles (B2-1f).
（製造例１１）
　プロピレングリコールの使用量を０．６２５質量部に変更したこと以外は製造例５と同様に実施し、表面架橋された重合体粒子（Ｂ２－１ｇ）を得た。 (Manufacturing Example 11)
The same procedure as in Production Example 5 was carried out except that the amount of propylene glycol used was changed to 0.625 parts by mass to obtain surface-crosslinked polymer particles (B2-1 g).
（製造例１２）
　プロピレングリコール０．１２５質量部をイソプロパノール（ＩＰＡ）０．１９７質量部（水酸基の総量（物質量）はプロピレングリコール０．１２５質量部と同等）に変更したこと以外は製造例５と同様に実施し、表面架橋された重合体粒子（Ｂ２－１ｈ）を得た。 (Manufacturing Example 12)
The same procedure as in Production Example 5 was carried out except that 0.125 parts by mass of propylene glycol was changed to 0.197 parts by mass of isopropanol (IPA) (the total amount of hydroxyl groups (amount of substance) was equivalent to 0.125 parts by mass of propylene glycol). , Surface crosslinked polymer particles (B2-1h) were obtained.
（製造例１３）
　プロピレングリコール０．１２５質量部をイソプロパノール０．３９５質量部に変更したこと以外は製造例５と同様に実施し、表面架橋された重合体粒子（Ｂ２－１ｉ）を得た。 (Manufacturing Example 13)
The same procedure as in Production Example 5 was carried out except that 0.125 parts by mass of propylene glycol was changed to 0.395 parts by mass of isopropanol to obtain surface-crosslinked polymer particles (B2-1i).
（製造例１４）
　重合体粒子（Ａ１－１）を重合体粒子（Ｂ１－２）に変更したこと以外は製造例１と同様に実施し、表面架橋された重合体粒子（Ｂ２－２ａ）を得た。 (Manufacturing Example 14)
The same procedure as in Production Example 1 was carried out except that the polymer particles (A1-1) were changed to the polymer particles (B1-2) to obtain surface-crosslinked polymer particles (B2-2a).
（製造例１５）
　重合体粒子（Ａ１－１）を重合体粒子（Ｂ１－２）に変更し、プロピレングリコールの使用量を０．６２５質量部に変更したこと以外は製造例１と同様に実施し、表面架橋された重合体粒子（Ｂ２－２ｂ）を得た。 (Manufacturing Example 15)
The same procedure as in Production Example 1 was carried out except that the polymer particles (A1-1) were changed to the polymer particles (B1-2) and the amount of propylene glycol used was changed to 0.625 parts by mass, and the surface was crosslinked. Polymer particles (B2-2b) were obtained.
（製造例１６）
　重合体粒子（Ａ１－１）を重合体粒子（α）に変更したこと以外は製造例１と同様に実施し、表面架橋された重合体粒子（Ｘ１１）を得た。 (Manufacturing Example 16)
The same procedure as in Production Example 1 was carried out except that the polymer particles (A1-1) were changed to the polymer particles (α), and surface-crosslinked polymer particles (X11) were obtained.
（製造例１７）
　重合体粒子（Ｘ１１）を目開き８５０μｍの篩及び目開き１８０μｍの篩で分級することにより、目開き８５０μｍの篩を通過し、かつ、目開き１８０μｍの篩を通過しなかった分画（篩上に残存した分画）である重合体粒子（Ｘ１２）を得た。 (Manufacturing Example 17)
By classifying the polymer particles (X11) with a sieve having an opening of 850 μm and a sieve having an opening of 180 μm, the fractions (on the sieve) that passed through the sieve having an opening of 850 μm and did not pass through the sieve having an opening of 180 μm. Polymer particles (X12), which are the fractions remaining in the above, were obtained.
（製造例１８）
　重合体粒子（Ｘ１１）を目開き８５０μｍの篩及び目開き１８０μｍの篩で分級することにより、目開き８５０μｍの篩及び目開き１８０μｍの篩を通過した分画である重合体粒子（Ｘ１３）を得た。 (Manufacturing Example 18)
By classifying the polymer particles (X11) with a sieve having an opening of 850 μm and a sieve having an opening of 180 μm, polymer particles (X13) which are fractions passed through a sieve having an opening of 850 μm and a sieve having an opening of 180 μm are obtained. It was.
（製造例１９）
　重合体粒子（Ａ１－１）を重合体粒子（β）に変更したこと以外は製造例１と同様に実施し、表面架橋された重合体粒子（Ｘ２１）を得た。 (Manufacturing Example 19)
The same procedure as in Production Example 1 was carried out except that the polymer particles (A1-1) were changed to the polymer particles (β) to obtain surface-crosslinked polymer particles (X21).
（製造例２０）
　重合体粒子（Ｘ２１）を目開き８５０μｍの篩及び目開き１８０μｍの篩で分級することにより、目開き８５０μｍの篩を通過し、かつ、目開き１８０μｍの篩を通過しなかった分画（篩上に残存した分画）である重合体粒子（Ｘ２２）を得た。 (Manufacturing Example 20)
By classifying the polymer particles (X21) with a sieve having an opening of 850 μm and a sieve having an opening of 180 μm, a fraction (on the sieve) that has passed through a sieve having an opening of 850 μm and has not passed through a sieve having an opening of 180 μm. Polymer particles (X22), which are the fractions remaining in the above, were obtained.
（製造例２１）
　重合体粒子（Ｘ２１）を目開き８５０μｍの篩及び目開き１８０μｍの篩で分級することにより、目開き８５０μｍの篩及び目開き１８０μｍの篩を通過した分画である重合体粒子（Ｘ２３）を得た。 (Manufacturing Example 21)
By classifying the polymer particles (X21) with a sieve having an opening of 850 μm and a sieve having an opening of 180 μm, polymer particles (X23) which are fractions passed through a sieve having an opening of 850 μm and a sieve having an opening of 180 μm are obtained. It was.
＜評価用吸水性樹脂粒子の準備＞
（実験例１）
　重合体粒子（Ａ２－１ａ）９０質量部及び重合体粒子（Ｂ２－１ａ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 <Preparation of water-absorbent resin particles for evaluation>
(Experimental Example 1)
After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1a) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例２）
　重合体粒子（Ａ２－１ａ）９０質量部及び重合体粒子（Ｂ２－１ｂ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 2)
After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1b) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例３）
　重合体粒子（Ａ２－１ａ）９０質量部及び重合体粒子（Ｂ２－１ｃ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 3)
After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1c) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例４）
　重合体粒子（Ａ２－１ａ）９０質量部及び重合体粒子（Ｂ２－１ｄ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 4)
After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1d) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例５）
　重合体粒子（Ａ２－１ａ）９０質量部及び重合体粒子（Ｂ２－１ｅ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 5)
After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1e) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例６）
　重合体粒子（Ａ２－１ａ）９０質量部及び重合体粒子（Ｂ２－１ｆ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 6)
After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1f) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例７）
　重合体粒子（Ａ２－１ａ）９０質量部及び重合体粒子（Ｂ２－１ｇ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 7)
After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1g) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例８）
　重合体粒子（Ａ２－１ａ）９０質量部及び重合体粒子（Ｂ２－１ｈ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 8)
After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1h) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例９）
　重合体粒子（Ａ２－１ａ）９０質量部及び重合体粒子（Ｂ２－１ｉ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 9)
After putting 90 parts by mass of polymer particles (A2-1a) and 10 parts by mass of polymer particles (B2-1i) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例１０）
　重合体粒子（Ａ２－２ａ）９０質量部及び重合体粒子（Ｂ２－２ａ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 10)
After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-2a) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例１１）
　重合体粒子（Ａ２－２ａ）９０質量部及び重合体粒子（Ｂ２－２ｂ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 11)
After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-2b) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例１２）
　重合体粒子（Ａ２－２ａ）９０質量部及び重合体粒子（Ｂ２－１ｅ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 12)
After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-1e) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例１３）
　重合体粒子（Ａ２－２ａ）９０質量部及び重合体粒子（Ｂ２－１ｆ）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 13)
After putting 90 parts by mass of polymer particles (A2-2a) and 10 parts by mass of polymer particles (B2-1f) into a 100 mL mayonnaise bottle, shake with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. To obtain water-absorbent resin particles.
（実験例１４）
　吸水性樹脂粒子として上述の重合体粒子（Ｘ１１）を準備した。 (Experimental Example 14)
The above-mentioned polymer particles (X11) were prepared as water-absorbent resin particles.
（実験例１５）
　重合体粒子（Ｘ１２）９０質量部及び重合体粒子（Ｘ１３）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 15)
90 parts by mass of polymer particles (X12) and 10 parts by mass of polymer particles (X13) are put into a 100 mL mayonnaise bottle, and then uniformly mixed by shaking with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. Water-absorbent resin particles were obtained.
（実験例１６）
　吸水性樹脂粒子として上述の重合体粒子（Ｘ２１）を準備した。 (Experimental Example 16)
The above-mentioned polymer particles (X21) were prepared as water-absorbent resin particles.
（実験例１７）
　重合体粒子（Ｘ２２）９０質量部及び重合体粒子（Ｘ２３）１０質量部を１００ｍＬのマヨネーズ瓶に投入した後、ペイントシェーカー（株式会社東洋精機製作所製）にて３０分振盪することにより均一混合して吸水性樹脂粒子を得た。 (Experimental Example 17)
90 parts by mass of polymer particles (X22) and 10 parts by mass of polymer particles (X23) are put into a 100 mL mayonnaise bottle, and then uniformly mixed by shaking with a paint shaker (manufactured by Toyo Seiki Seisakusho Co., Ltd.) for 30 minutes. Water-absorbent resin particles were obtained.
＜吸水特性の評価＞
　上述の各製造例の重合体粒子、並びに、各実験例の吸水性樹脂粒子について下記の吸水特性を測定した。上述の各製造例の重合体粒子の測定結果を表１に示す。上述の各実験例の吸水性樹脂粒子の測定結果を表２に示す。 <Evaluation of water absorption characteristics>
The following water absorption characteristics were measured for the polymer particles of each of the above-mentioned production examples and the water-absorbent resin particles of each experimental example. Table 1 shows the measurement results of the polymer particles of each of the above-mentioned production examples. Table 2 shows the measurement results of the water-absorbent resin particles of each of the above-mentioned experimental examples.
（ＣＲＣ）
　ＥＤＡＮＡ法（ＮＷＳＰ　２４１．０．Ｒ２（１５）、ｐａｇｅ．７６９～７７８）を参考にＣＲＣを下記の手順で測定した。上述の吸水性樹脂粒子（α）及び吸水性樹脂粒子（β）のＣＲＣについても同様に測定した。測定は、温度２５℃±２℃、湿度５０％±１０％の環境下で行った。 (CRC)
The CRC was measured by the following procedure with reference to the EDANA method (NWSP 241.0.R2 (15), page.769-778). The CRC of the above-mentioned water-absorbent resin particles (α) and water-absorbent resin particles (β) was also measured in the same manner. The measurement was carried out in an environment where the temperature was 25 ° C. ± 2 ° C. and the humidity was 50% ± 10%.
　６０ｍｍ×１７０ｍｍの大きさの不織布（製品名：ヒートパックＭＷＡ－１８、日本製紙パピリア株式会社製）を長手方向に半分に折ることで６０ｍｍ×８５ｍｍの大きさに調整した。長手方向に延びる両辺のそれぞれにおいて不織布同士をヒートシールで圧着することにより６０ｍｍ×８５ｍｍの不織布バッグを作製した（幅５ｍｍの圧着部を長手方向に沿って両辺に形成した）。不織布バッグの内部に測定対象粒子を０．２ｇ精秤し収容した。その後、短手方向に延びる残りの一辺をヒートシールで圧着することにより不織布バッグを閉じた。 A non-woven fabric with a size of 60 mm x 170 mm (product name: Heat Pack MWA-18, manufactured by Nippon Paper Papylia Co., Ltd.) was folded in half in the longitudinal direction to adjust the size to 60 mm x 85 mm. A 60 mm × 85 mm non-woven fabric bag was produced by crimping the non-woven fabrics to each other on both sides extending in the longitudinal direction with a heat seal (a crimped portion having a width of 5 mm was formed on both sides along the longitudinal direction). 0.2 g of the particles to be measured were precisely weighed and contained inside the non-woven fabric bag. Then, the non-woven fabric bag was closed by crimping the remaining one side extending in the lateral direction with a heat seal.
　不織布バッグが折り重ならない状態で、ステンレス製バット（２４０ｍｍ×３２０ｍｍ×４５ｍｍ）に収容された生理食塩水１０００ｇ上に不織布バッグを浮かべることにより、不織布バッグの全体を完全に湿らせた。不織布バッグを生理食塩水に投入してから１分後にスパチュラにて不織布バッグを生理食塩水に浸漬することにより、ゲルが収容された不織布バッグを得た。 The entire non-woven fabric bag was completely moistened by floating the non-woven fabric bag on 1000 g of physiological saline contained in a stainless steel vat (240 mm × 320 mm × 45 mm) without folding the non-woven fabric bag. One minute after the non-woven fabric bag was put into the physiological saline solution, the non-woven fabric bag was immersed in the physiological saline solution with a spatula to obtain a non-woven fabric bag containing the gel.
　不織布バッグを生理食塩水に投入してから３０分後（浮かべた時間１分、及び、浸漬時間２９分の合計）に生理食塩水の中から不織布バッグを取り出した。そして、遠心分離機（株式会社コクサン製、型番：Ｈ－１２２）に不織布バッグを入れた。遠心分離機における遠心力が２５０Ｇに到達した後、３分間不織布バッグの脱水を行った。脱水後、ゲルの質量を含む不織布バッグの質量Ｍａを秤量した。測定対象粒子を収容することなく不織布バッグに対して上述の操作と同様の操作を施し、不織布バッグの質量Ｍｂを測定した。下記式に基づきＣＲＣを算出した。Ｍｃは、測定に用いた測定対象粒子の質量０．２ｇの精秤値である。
　　ＣＲＣ［ｇ／ｇ］　＝　｛（Ｍａ－Ｍｂ）－Ｍｃ｝／Ｍｃ Thirty minutes after the non-woven fabric bag was put into the physiological saline solution (a total of 1 minute of floating time and 29 minutes of immersion time), the non-woven fabric bag was taken out from the physiological saline solution. Then, the non-woven fabric bag was put in a centrifuge (manufactured by Kokusan Co., Ltd., model number: H-122). After the centrifugal force in the centrifuge reached 250 G, the non-woven fabric bag was dehydrated for 3 minutes. After dehydration, the mass Ma of the non-woven fabric bag containing the mass of the gel was weighed. The non-woven fabric bag was subjected to the same operation as described above without accommodating the particles to be measured, and the mass Mb of the non-woven fabric bag was measured. The CRC was calculated based on the following formula. Mc is a precise value of 0.2 g of the mass of the particle to be measured used for the measurement.
CRC [g / g] = {(Ma-Mb) -Mc} / Mc
（加圧下吸収倍率（ＡＡＰ））
　図２に示す測定装置１１０を用いて４．８３ｋＰａ加圧下の吸収倍率（ＡＡＰ）を測定した。まず、４．８３ｋＰａの圧力になるように調整した重り１１２（断面：円形）、（内径）６０ｍｍのプラスチック製の円筒１１４、及び、円筒１１４の一端（底面）に配置された４００メッシュ（目開き３８μｍ）の金網１１６を備える測定装置１１０を準備した。重り１１２は、円板部１１２ａと、円板部１１２ａに垂直な方向に円板部１１２ａの中央から延びる棒状部１１２ｂと、棒状部１１２ｂに挿入される貫通孔を中央に有する円柱部１１２ｃと、を有している。重り１１２の円板部１１２ａは、円筒１１４の内部において円筒１１４の長手方向に移動可能であるように円筒１１４の内径と略同等の径を有している。円柱部１１２ｃの径は円板部１１２ａの径よりも小さい。円筒１１４の一端は、開放されているものの金網１１６に遮蔽されており、円筒１１４の他端は、重り１１２が挿入できるように開放されている。円筒１１４の内部において金網１１６上に０．９０ｇの測定対象粒子１２０を均一に散布した。そして、円筒１１４の内部に重り１１２を挿入して測定対象粒子１２０上に重り１１２を載せた後、測定装置１１０の全体の質量（測定装置１１０及び吸液前の測定対象粒子１２０の総質量）Ｗａ［ｇ］を測定した。 (Absorption ratio under pressure (AAP))
The absorption magnification (AAP) under a pressure of 4.83 kPa was measured using the measuring device 110 shown in FIG. First, a weight 112 (cross section: circular) adjusted to a pressure of 4.83 kPa, a plastic cylinder 114 with an (inner diameter) of 60 mm, and a 400 mesh (opening) arranged at one end (bottom surface) of the cylinder 114. A measuring device 110 provided with a wire mesh 116 of 38 μm) was prepared. The weight 112 includes a disc portion 112a, a rod-shaped portion 112b extending from the center of the disc portion 112a in a direction perpendicular to the disc portion 112a, and a cylindrical portion 112c having a through hole inserted into the rod-shaped portion 112b in the center. have. The disk portion 112a of the weight 112 has a diameter substantially equal to the inner diameter of the cylinder 114 so that it can be moved in the longitudinal direction of the cylinder 114 inside the cylinder 114. The diameter of the cylindrical portion 112c is smaller than the diameter of the disc portion 112a. Although one end of the cylinder 114 is open, it is shielded by a wire mesh 116, and the other end of the cylinder 114 is open so that the weight 112 can be inserted. Inside the cylinder 114, 0.90 g of particles 120 to be measured were uniformly sprayed on the wire mesh 116. Then, after the weight 112 is inserted into the cylinder 114 and the weight 112 is placed on the measurement target particle 120, the total mass of the measurement device 110 (the total mass of the measurement device 110 and the measurement target particle 120 before liquid absorption). Wa [g] was measured.
　直径１５０ｍｍのステンレスシャーレ１３０の凹部における底面の中央に直径９０ｍｍ、厚さ７ｍｍのガラスフィルター１４０（ＩＳＯ４７９３　Ｐ－２５０）を置いた後、水面がガラスフィルター１４０の上面と同じ高さになるように０．９０質量％の塩化ナトリウム水溶液（２５℃±２℃）を加えた。ガラスフィルター１４０上に直径９０ｍｍの１枚のろ紙１５０（ＡＤＶＡＮＴＥＣ東洋株式会社、製品名：（Ｎｏ．３）、厚さ０．２３ｍｍ、保留粒子径５μｍ）を載せ、表面が全て濡れるようにし、かつ、過剰の液を除いた。そして、ろ紙１５０上に上述の測定装置１１０を載せ、液を荷重下で吸収させた。１時間後、測定装置１１０を持ち上げ、測定装置１１０の全体の質量（測定装置１１０及び吸液後の測定対象粒子１２０の総質量）Ｗｂ［ｇ］を測定した。 After placing a glass filter 140 (ISO4793 P-250) with a diameter of 90 mm and a thickness of 7 mm in the center of the bottom surface of the recess of the stainless steel dish 130 with a diameter of 150 mm, 0 so that the water surface is at the same height as the upper surface of the glass filter 140. A 90% by mass aqueous sodium chloride solution (25 ° C ± 2 ° C) was added. A sheet of filter paper 150 (ADVANTEC Toyo Co., Ltd., product name: (No. 3), thickness 0.23 mm, reserved particle diameter 5 μm) with a diameter of 90 mm is placed on the glass filter 140 so that the entire surface is wet and the surface is completely wet. , Excess liquid was removed. Then, the above-mentioned measuring device 110 was placed on the filter paper 150 to absorb the liquid under a load. After 1 hour, the measuring device 110 was lifted, and the total mass of the measuring device 110 (total mass of the measuring device 110 and the measurement target particle 120 after absorbing the liquid) Wb [g] was measured.
　そして、Ｗａ及びＷｂから、下記式に基づき４．８３ｋＰａ加圧下の吸収倍率（ＡＡＰ）［ｇ／ｇ］を算出した。
　　ＡＡＰ［ｇ／ｇ］＝（Ｗｂ［ｇ］－Ｗａ［ｇ］）／０．９０［ｇ］ Then, the absorption ratio (AAP) [g / g] under the pressure of 4.83 kPa was calculated from Wa and Wb based on the following formula.
AAP [g / g] = (Wb [g] -Wa [g]) /0.90 [g]
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　実験例１と実験例１５との対比、及び、実験例１０と実験例１７との対比によれば、分級して得られた複数の重合体粒子群のそれぞれに表面架橋を施した後に混合した場合（実験例１、１０）には、表面架橋前に分級することなく表面架橋後に分級して得られた複数の重合体粒子群を混合した場合（実験例１５、１７）と比較して、加圧下における優れた吸水特性が得られることが分かる。 According to the comparison between Experimental Example 1 and Experimental Example 15 and the comparison between Experimental Example 10 and Experimental Example 17, each of the plurality of polymer particle groups obtained by classification was surface-crosslinked and then mixed. In the case (Experimental Examples 1 and 10), as compared with the case (Experimental Examples 15 and 17), a plurality of polymer particle groups obtained by classifying after the surface cross-linking without classifying before the surface cross-linking were mixed. It can be seen that excellent water absorption characteristics under pressure can be obtained.
　製造例１と製造例２、３との対比によれば、目開き２１２μｍ以下の篩上に残存する重合体粒子群に施す表面架橋における表面架橋剤の混合温度及びアルコールの使用量が、加圧下における吸水特性に大きな影響を与えないことが分かる。一方、製造例５と製造例８、９との対比、及び、製造例５と製造例１０、１１との対比によれば、目開き２１２μｍ以下の篩を通過した重合体粒子群に施す表面架橋における表面架橋剤の混合温度及びアルコールの使用量が、加圧下における吸水特性に大きく寄与することが分かる。同様に、製造例５と製造例６、７との対比によれば、目開き２１２μｍ以下の篩を通過した重合体粒子群に施す表面架橋における表面架橋剤の使用量が、加圧下における吸水特性に大きく寄与することが分かる。 According to the comparison between Production Example 1 and Production Examples 2 and 3, the mixing temperature of the surface cross-linking agent and the amount of alcohol used in the surface cross-linking applied to the polymer particle group remaining on the sieve having a mesh size of 212 μm or less are under pressure. It can be seen that it does not significantly affect the water absorption characteristics of. On the other hand, according to the comparison between Production Example 5 and Production Examples 8 and 9, and the comparison between Production Example 5 and Production Examples 10 and 11, surface cross-linking applied to the polymer particle group passing through a sieve having a mesh size of 212 μm or less. It can be seen that the mixing temperature of the surface cross-linking agent and the amount of alcohol used in the above contribute greatly to the water absorption characteristics under pressure. Similarly, according to the comparison between Production Examples 5 and 6 and 7, the amount of the surface cross-linking agent used in the surface cross-linking applied to the polymer particle group passing through the sieve having a mesh size of 212 μm or less is the water absorption characteristic under pressure. It can be seen that it greatly contributes to.
　製造例５と製造例１２、１３との対比によれば、目開き２１２μｍ以下の篩を通過した重合体粒子群に、イソプロパノールを用いて表面架橋を施す場合、プロピレングリコールを用いて表面架橋を施す場合と比較して、加圧下における吸水特性が大きく向上しづらいことが分かる。一方、実験例１と実験例８、９との対比によれば、これらの製造例の重合体粒子群と、目開き２１２μｍ以下の篩上に残存する重合体粒子群に表面架橋を施して得られる重合体粒子群と、を混合する場合では、イソプロパノールを用いた表面架橋を施して得られる重合体粒子群を用いることにより、プロピレングリコールを用いて表面架橋を施す場合と比較して、加圧下における吸水特性が大きく向上することが分かる。 According to the comparison between Production Examples 5 and 12 and 13, when surface cross-linking is performed using isopropanol on a group of polymer particles that have passed through a sieve having a mesh size of 212 μm or less, surface cross-linking is performed using propylene glycol. It can be seen that it is difficult to greatly improve the water absorption characteristics under pressure as compared with the case. On the other hand, according to the comparison between Experimental Example 1 and Experimental Examples 8 and 9, the polymer particle group of these production examples and the polymer particle group remaining on the sieve having a mesh size of 212 μm or less are surface-crosslinked. In the case of mixing with the polymer particle group to be obtained, by using the polymer particle group obtained by surface cross-linking with isopropanol, the pressure is increased as compared with the case of surface cross-linking with propylene glycol. It can be seen that the water absorption characteristics in the above are greatly improved.
　１０…吸収体、１０ａ…吸水性樹脂粒子、１０ｂ…繊維層、２０ａ，２０ｂ…コアラップ、３０…液体透過性シート、４０…液体不透過性シート、１００…吸収性物品、１１０…測定装置、１１２…重り、１１２ａ…円板部、１１２ｂ…棒状部、１１２ｃ…円柱部、１１４…円筒、１１６…金網、１２０…測定対象粒子、１３０…ステンレスシャーレ、１４０…ガラスフィルター、１５０…ろ紙。 10 ... Absorbent, 10a ... Water-absorbent resin particles, 10b ... Fiber layer, 20a, 20b ... Core wrap, 30 ... Liquid permeable sheet, 40 ... Liquid permeable sheet, 100 ... Absorbent article, 110 ... Measuring device, 112 ... Weight, 112a ... Disc, 112b ... Rod, 112c ... Cylindrical, 114 ... Cylindrical, 116 ... Wire mesh, 120 ... Particles to be measured, 130 ... Stainless steel, 140 ... Glass filter, 150 ... Filter paper.

Claims (15)

  1. 　目開き２１２μｍ以下の篩Ｓ１で重合体粒子群を分級した際に当該篩Ｓ１上に残存する重合体粒子群Ａ１に表面架橋を施して得られる重合体粒子群Ａ２と、
    　目開き２１２μｍ以下の篩Ｓ２で重合体粒子群を分級した際に当該篩Ｓ２を通過した重合体粒子群Ｂ１に表面架橋を施して得られる重合体粒子群Ｂ２と、を混合することにより吸水性樹脂粒子を得る工程を備える、吸水性樹脂粒子の製造方法。     When the polymer particle group is classified by the sieve S1 having a mesh size of 212 μm or less, the polymer particle group A2 remaining on the sieve S1 is surface-crosslinked to obtain the polymer particle group A2.
    Water absorption by mixing with the polymer particle group B2 obtained by subjecting the polymer particle group B1 that has passed through the sieve S2 to surface cross-linking when the polymer particle group is classified by the sieve S2 having a mesh size of 212 μm or less. A method for producing water-absorbent resin particles, which comprises a step of obtaining resin particles.
  2. 　重合体粒子群Ｃを前記篩Ｓ１（前記篩Ｓ１及び前記篩Ｓ２は互いに同一の篩である）で分級することにより前記重合体粒子群Ａ１及び前記重合体粒子群Ｂ１を得る工程と、
    　前記重合体粒子群Ａ１に表面架橋を施して前記重合体粒子群Ａ２を得る工程と、
    　前記重合体粒子群Ｂ１に表面架橋を施して前記重合体粒子群Ｂ２を得る工程と、を更に備える、請求項１に記載の吸水性樹脂粒子の製造方法。     A step of obtaining the polymer particle group A1 and the polymer particle group B1 by classifying the polymer particle group C with the sieve S1 (the sieve S1 and the sieve S2 are the same sieves).
    A step of subjecting the polymer particle group A1 to surface cross-linking to obtain the polymer particle group A2,
    The method for producing water-absorbent resin particles according to claim 1, further comprising a step of subjecting the polymer particle group B1 to surface cross-linking to obtain the polymer particle group B2.
  3. 　前記重合体粒子群Ｃを前記篩Ｓ１で前記重合体粒子群Ａ１及び前記重合体粒子群Ｂ１の二つに分級する、請求項２に記載の吸水性樹脂粒子の製造方法。 The method for producing water-absorbent resin particles according to claim 2, wherein the polymer particle group C is classified into two, the polymer particle group A1 and the polymer particle group B1, by the sieve S1.
  4. 　重合体粒子群Ｄ１を前記篩Ｓ１で分級することにより前記重合体粒子群Ａ１を得る工程と、
    　前記重合体粒子群Ａ１に表面架橋を施して前記重合体粒子群Ａ２を得る工程と、
    　前記重合体粒子群Ｄ１とは異なる重合体粒子群Ｄ２を前記篩Ｓ２で分級することにより前記重合体粒子群Ｂ１を得る工程と、
    　前記重合体粒子群Ｂ１に表面架橋を施して前記重合体粒子群Ｂ２を得る工程と、を更に備える、請求項１に記載の吸水性樹脂粒子の製造方法。     A step of obtaining the polymer particle group A1 by classifying the polymer particle group D1 with the sieve S1 and a step of obtaining the polymer particle group A1.
    A step of subjecting the polymer particle group A1 to surface cross-linking to obtain the polymer particle group A2,
    A step of obtaining the polymer particle group B1 by classifying the polymer particle group D2 different from the polymer particle group D1 with the sieve S2.
    The method for producing water-absorbent resin particles according to claim 1, further comprising a step of subjecting the polymer particle group B1 to surface cross-linking to obtain the polymer particle group B2.
  5. 　前記篩Ｓ１及び前記篩Ｓ２の前記目開きが互いに同一である、請求項４に記載の吸水性樹脂粒子の製造方法。 The method for producing water-absorbent resin particles according to claim 4, wherein the meshes of the sieve S1 and the sieve S2 are the same as each other.
  6. 　１００質量部の前記重合体粒子群Ａ２と、５０質量部未満の前記重合体粒子群Ｂ２と、を混合する、請求項１～５のいずれか一項に記載の吸水性樹脂粒子の製造方法。 The method for producing water-absorbent resin particles according to any one of claims 1 to 5, wherein 100 parts by mass of the polymer particle group A2 and less than 50 parts by mass of the polymer particle group B2 are mixed.
  7. 　前記吸水性樹脂粒子が、エチレン性不飽和単量体に由来する構造単位を有する、請求項１～６のいずれか一項に記載の吸水性樹脂粒子の製造方法。 The method for producing water-absorbent resin particles according to any one of claims 1 to 6, wherein the water-absorbent resin particles have a structural unit derived from an ethylenically unsaturated monomer.
  8. 　前記エチレン性不飽和単量体が、（メタ）アクリル酸及びその塩からなる群より選ばれる少なくとも１種の化合物を含む、請求項７に記載の吸水性樹脂粒子の製造方法。 The method for producing water-absorbent resin particles according to claim 7, wherein the ethylenically unsaturated monomer contains at least one compound selected from the group consisting of (meth) acrylic acid and a salt thereof.
  9. 　前記重合体粒子群Ｂ１と表面架橋剤とを０～２０℃で混合して前記重合体粒子群Ｂ１に表面架橋を施す、請求項１～８のいずれか一項に記載の吸水性樹脂粒子の製造方法。 The water-absorbent resin particles according to any one of claims 1 to 8, wherein the polymer particle group B1 and the surface cross-linking agent are mixed at 0 to 20 ° C. to perform surface cross-linking on the polymer particle group B1. Production method.
  10. 　０．５～１０質量部のカーボネート化合物を含有する表面架橋剤溶液を用いて１００質量部の前記重合体粒子群Ｂ１に表面架橋を施す、請求項１～９のいずれか一項に記載の吸水性樹脂粒子の製造方法。 The water absorption according to any one of claims 1 to 9, wherein 100 parts by mass of the polymer particle group B1 is surface-crosslinked with a surface cross-linking agent solution containing 0.5 to 10 parts by mass of a carbonate compound. Method for producing sex resin particles.
  11. 　アルコール及び水を含有する表面架橋剤溶液を用いて前記重合体粒子群Ｂ１に表面架橋を施し、
    　前記水に対する前記アルコールの体積比が０．２５～２．００である、請求項１～１０のいずれか一項に記載の吸水性樹脂粒子の製造方法。     The polymer particle group B1 was surface-crosslinked using a surface cross-linking agent solution containing alcohol and water.
    The method for producing water-absorbent resin particles according to any one of claims 1 to 10, wherein the volume ratio of the alcohol to water is 0.25 to 2.00.
  12. 　アルコールを２０～８０質量％含有する表面架橋剤溶液を用いて前記重合体粒子群Ｂ１に表面架橋を施す、請求項１～１１のいずれか一項に記載の吸水性樹脂粒子の製造方法。 The method for producing water-absorbent resin particles according to any one of claims 1 to 11, wherein the polymer particle group B1 is surface-crosslinked using a surface cross-linking agent solution containing 20 to 80% by mass of alcohol.
  13. 　イソプロパノールを含有する表面架橋剤溶液を用いて前記重合体粒子群Ｂ１に表面架橋を施す、請求項１～１２のいずれか一項に記載の吸水性樹脂粒子の製造方法。 The method for producing water-absorbent resin particles according to any one of claims 1 to 12, wherein the polymer particle group B1 is subjected to surface cross-linking using a surface cross-linking agent solution containing isopropanol.
  14. 　目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した重合体粒子群Ｂ１と、表面架橋剤と、を０～２０℃で混合して前記重合体粒子群Ｂ１に表面架橋を施す工程を備える、重合体粒子の製造方法。 When the polymer particle group was classified with a sieve having a mesh size of 212 μm or less, the polymer particle group B1 that passed through the sieve and the surface cross-linking agent were mixed at 0 to 20 ° C. and surfaced on the polymer particle group B1. A method for producing polymer particles, which comprises a step of subjecting a crosslink.
  15. 　アルコール及び水を含有する表面架橋剤溶液を用いて、目開き２１２μｍ以下の篩で重合体粒子群を分級した際に当該篩を通過した重合体粒子群Ｂ１に表面架橋を施す工程を備え、
    　前記水に対する前記アルコールの体積比が０．２５～２．００である、重合体粒子の製造方法。     A step of surface cross-linking the polymer particle group B1 that has passed through the sieve when the polymer particle group is classified by a sieve having a mesh size of 212 μm or less using a surface cross-linking agent solution containing alcohol and water is provided.
    A method for producing polymer particles, wherein the volume ratio of the alcohol to water is 0.25 to 2.00.
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JP2004002891A (en) * 1994-10-26 2004-01-08 Nippon Shokubai Co Ltd Pelletized particle of water absorptive resin, absorptive article containing the particle and methgod for producing the pelletized particle of the water absorptive resin
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