WO2019059019A1 - Water-absorbing resin composition and production method therefor - Google Patents

Water-absorbing resin composition and production method therefor Download PDF

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Publication number
WO2019059019A1
WO2019059019A1 PCT/JP2018/033395 JP2018033395W WO2019059019A1 WO 2019059019 A1 WO2019059019 A1 WO 2019059019A1 JP 2018033395 W JP2018033395 W JP 2018033395W WO 2019059019 A1 WO2019059019 A1 WO 2019059019A1
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Prior art keywords
water
resin composition
absorbent resin
weight
crosslinked polymer
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PCT/JP2018/033395
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French (fr)
Japanese (ja)
Inventor
宮島　徹
佑介 松原
艶ブン 王
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Ｓｄｐグローバル株式会社
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Priority to CN201880060747.2A priority Critical patent/CN111094441B/en
Priority to JP2019543557A priority patent/JPWO2019059019A1/en
Publication of WO2019059019A1 publication Critical patent/WO2019059019A1/en
Priority to JP2022205177A priority patent/JP2023029421A/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
    • C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
    • C08F20/04—Acids, Metal salts or ammonium salts thereof
    • C08F20/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
    • 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
    • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/24—Acids; Salts thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof

Definitions

  • the present invention relates to a water absorbent resin composition and a method for producing the same.
  • a water absorbent resin mainly composed of hydrophilic fibers such as pulp and acrylic acid (salt) is widely used as an absorbent. From the viewpoint of improving Quality of Life (QOL) in recent years, the demand for these sanitary materials has shifted to lighter and thinner ones, and along with this, it has become desirable to reduce the amount of hydrophilic fibers used. .
  • the crosslink density of the water absorbing resin surface is increased by crosslinking the surface of the water absorbing resin, deformation of the swelling gel surface is suppressed, and gel gaps are efficiently formed.
  • a method is already known (see, for example, Patent Document 1).
  • the surface cross-linking alone was not sufficient to make the liquid permeability between the swollen gels sufficient.
  • An object of the present invention is to provide a water-absorbent resin which is excellent in blocking resistance at the time of initial swelling, and excellent in liquid permeability between swollen gels and water absorption performance under load.
  • the present invention relates to a water-soluble vinyl monomer (a1) and / or a cross-linked polymer (A) comprising a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis and a cross-linking agent (b)
  • a water-absorbent resin composition comprising a water-insoluble alumina-containing fine particle (c) and a water-soluble aluminum salt (d), and having a surface aluminum coverage of 60 to 100% of the crosslinked polymer (A);
  • An aqueous solution containing 0.05 to 5% by weight based on the weight of the crosslinked polymer (A) is added, and then the crosslinked polymer (A) is surface-crosslinked.
  • Surface aluminum coverage Is a
  • the water-absorbent resin composition of the present invention and the water-absorbent resin composition obtained by the production method of the present invention have an initial stage by covering at least a part of the surface with water-insoluble alumina-containing fine particles and a water-soluble aluminum salt. Blocking resistance at the time of swelling is high, and liquid permeability between the swollen gels is very excellent. Therefore, stable absorption performance (for example, liquid diffusivity, absorption rate, absorption amount, etc.) is exhibited stably in various usage conditions.
  • the water-absorbent resin composition of the present invention comprises a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis and a crosslinking agent (b) as essential constitutional units. It contains a crosslinked polymer (A), water-insoluble alumina-containing fine particles (c) and a water-soluble aluminum salt (d).
  • water-soluble vinyl monomer (a1) in the present invention there is no particular limitation on the water-soluble vinyl monomer (a1) in the present invention, and known monomers, for example, at least one water-soluble substituent disclosed in paragraphs 0007 to 0023 of Patent No. 3648553 and ethylenic non Vinyl monomers having a saturated group (for example, anionic vinyl monomers, nonionic vinyl monomers and cationic vinyl monomers), anionic vinyl monomers disclosed in paragraphs 0009 to 0024 of JP-A No.
  • nonionic Vinyl monomer and cationic vinyl monomer selected from the group consisting of carboxy group, sulfo group, phosphono group, hydroxyl group, carbamoyl group, amino group and ammonio group disclosed in paragraphs 0041 to 0051 of JP-A-2005-75982 At least one Vinyl monomer having can be used.
  • a vinyl monomer (a2) [hereinafter, also referred to as a hydrolyzable vinyl monomer (a2), which becomes a water-soluble vinyl monomer (a1) by hydrolysis].
  • a vinyl monomer having at least one hydrolysable substituent which becomes a water-soluble substituent by hydrolysis disclosed in paragraphs 0024 to 0025 of Japanese Patent No. 3648553, JP-A
  • At least one hydrolyzable substituent [1,3-oxo-2-oxapropylene (-CO-O-CO-) group, an acyl group and a cyano group disclosed in paragraphs 0052 to 0055 of the publication No. 2005-75982.
  • the water-soluble vinyl monomer means a vinyl monomer which dissolves at least 100 g in 100 g of water at 25 ° C.
  • the hydrolysability in a hydrolysable vinyl monomer (a2) means the property which is hydrolyzed by the effect
  • the hydrolysis of the hydrolyzable vinyl monomer (a2) may be performed during polymerization, after polymerization, or both of them, but after polymerization is preferable from the viewpoint of the absorption performance of the resulting water-absorbent resin composition.
  • water-soluble vinyl monomers (a1) are preferable from the viewpoint of absorption performance and the like, and anionic vinyl monomers, carboxy (salt) groups, sulfo (salt) groups, amino groups, carbamoyl groups and ammonio groups are more preferable.
  • vinyl monomers having a mono-, di- or tri-alkylammonio group more preferably vinyl monomers having a carboxy (salt) group or carbamoyl group, particularly preferably (meth) acrylic acid (salt) and (meth) ) Acrylamide, in particular (meth) acrylic acid (salt), most preferred acrylic acid (salt).
  • (meth) acrylic acid (salt) means acrylic acid, acrylic acid salt, methacrylic acid or methacrylic acid salt
  • (meth) acrylamide means acrylamide or methacrylamide.
  • alkali metal (lithium, sodium and potassium etc.) salt, alkaline earth metal (magnesium and calcium etc.) salt, ammonium (NH 4 ) salt etc. are mentioned.
  • alkali metal salts and ammonium salts are preferable from the viewpoint of absorption performance and the like, more preferable are alkali metal salts, and particularly preferable are sodium salts.
  • a water-soluble vinyl monomer (a1) or a hydrolyzable vinyl monomer (a2) When either a water-soluble vinyl monomer (a1) or a hydrolyzable vinyl monomer (a2) is used as a structural unit, one type may be used alone as a structural unit, and two or more types may also be used as a structural unit as necessary. good. The same applies to the case where the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as structural units.
  • their content molar ratio [(a1) / (a2)] is preferably 75/25 to 99/1. And more preferably 85/15 to 95/5, particularly preferably 90/10 to 93/7, and most preferably 91/9 to 92/8. Within this range, the absorption performance is further improved.
  • water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) as the structural unit of the crosslinked polymer (A), other vinyl monomers (a3) copolymerizable with these as the structural unit Can.
  • the other vinyl monomers (a3) may be used alone or in combination of two or more.
  • Aliphatic ethylenic monomers having 2 to 20 carbon atoms Alkenes (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.); and alkadienes (butadiene, isoprene etc.), etc.
  • the content (mol%) of the other vinyl monomer (a3) units is based on the total number of moles of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit from the viewpoint of absorption performance etc. It is preferably 0 to 5, more preferably 0 to 3, particularly preferably 0 to 2, particularly preferably 0 to 1.5, and the content of the other vinyl monomer (a3) unit is preferably from the viewpoint of absorption performance and the like. Most preferably, it is 0 mol%.
  • the crosslinking agent (b) is not particularly limited and is known (for example, it reacts with a crosslinking agent having two or more ethylenic unsaturated groups disclosed in paragraphs 0031 to 0034 of Japanese Patent No. 3648553, a water-soluble substituent).
  • JP-A 2003-165883 having at least one functional group and at least one crosslinking agent having at least one ethylenically unsaturated group, and at least two functional groups capable of reacting with a water-soluble substituent
  • Crosslinking agents such as disclosed crosslinkable vinyl monomer) can be used to.
  • a crosslinking agent having two or more ethylenically unsaturated groups is preferable, and poly (meth) allyl ether of polyhydric alcohol having 2 to 40 carbon atoms, more preferably carbon number is more preferable.
  • the crosslinking agent (b) may be used alone or in combination of two or more.
  • the content (mol%) of the crosslinker (b) unit is (a1) to (a1) when the other vinyl monomer (a3) of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit is used It is preferably 0.001 to 5, more preferably 0.005 to 3, particularly preferably 0.01 to 1, based on the total number of moles of (a3). Within this range, the absorption performance is further improved.
  • crosslinked polymer (A) As a method of producing the crosslinked polymer (A), known solution polymerization (diathermal polymerization, thin film polymerization, spray polymerization method, etc .; JP-A-55-133413, etc.), known suspension polymerization method, reverse phase polymerization, etc.
  • a water-containing gel polymer (consisting of a cross-linked polymer and water) obtained by turbid polymerization (JP-B 54-30710, JP-A 56-26909, JP-A 1-5 808, etc.) may be used if necessary. It can be obtained by heat drying and crushing.
  • the crosslinked polymer (A) may be used alone or in combination of two or more.
  • the solution polymerization method is preferable, and the aqueous solution polymerization method is particularly preferable since it is not necessary to use an organic solvent etc. and advantageous in terms of production cost, and the water retention amount is large and water soluble.
  • the aqueous solution adiabatic polymerization method is most preferable because a water-absorbent resin with a small amount of components is obtained, and temperature control at the time of polymerization is unnecessary.
  • aqueous solution polymerization When aqueous solution polymerization is performed, a mixed solvent containing water and an organic solvent can be used, and as the organic solvent, methanol, ethanol, acetone, methyl ethyl ketone, N, N-dimethylformamide, dimethyl sulfoxide and two or more of them can be used.
  • the amount (% by weight) of the organic solvent used is preferably 40 or less, more preferably 30 or less based on the weight of water.
  • a catalyst When a catalyst is used for the polymerization, conventionally known catalysts for radical polymerization can be used.
  • azo compounds azobisisobutyronitrile, azobiscyanovaleric acid and 2,2'-azobis (2-amidinopropane) hydrochloride are used.
  • inorganic peroxides eg hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate
  • organic peroxides benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, succinic acid peroxide Oxides and di (2-ethoxyethyl) peroxydicarbonate etc
  • redox catalysts sulfites or bisulfites of alkali metals, ammonium sulfite, ammonium bisulfite and ascorbic acid etc, reducing agents and persulfates of alkali metals, Oxidation of ammonium persulfate, hydrogen peroxide and organic peroxides And the like, and the like.
  • the amount (% by weight) of the radical polymerization catalyst used is the water soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), and the other vinyl monomers (a3) of (a1) to (a3) Based on the total weight, 0.0005 to 5 is preferable, and more preferably 0.001 to 2.
  • a polymerization control agent such as a chain transfer agent may be used in combination, and specific examples thereof include sodium hypophosphite, sodium phosphite, alkyl mercaptan, alkyl halide, thiocarbonyl compound Etc. These polymerization control agents may be used alone, or two or more of these may be used in combination.
  • the use amount (% by weight) of the polymerization control agent is the water soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), and the other vinyl monomers (a3) of (a1) to (a3) Based on the total weight, 0.0005 to 5 is preferable, and more preferably 0.001 to 2.
  • the polymerization may be carried out in the presence of a conventionally known dispersant or surfactant, if necessary.
  • a hydrocarbon solvent such as xylene, normal hexane and normal heptane which are conventionally known.
  • the polymerization initiation temperature can be appropriately adjusted depending on the type of catalyst used, but it is preferably 0 to 100 ° C., more preferably 2 to 80 ° C.
  • the solvent is preferably distilled off after the polymerization.
  • the content (% by weight) of the organic solvent after distillation is preferably 0 to 10, more preferably 0 to 5, particularly preferably, based on the weight of the crosslinked polymer (A). Is 0-3, most preferably 0-1. Within this range, the absorption performance of the water-absorbent resin composition is further improved.
  • the water content after distillation is preferably 0 to 20, more preferably 1 to 10, particularly preferably 2 to 9, based on the weight of the crosslinked polymer (A). Most preferably, it is 3-8. Within this range, the absorption performance is further improved.
  • the water-containing gel-like product (hereinafter abbreviated as water-containing gel) in which the crosslinked polymer (A) contains water can be obtained by the polymerization method described above, and the crosslinked polymer (A) can be obtained by further drying the water-containing gel. You can get it.
  • an acid group-containing monomer such as acrylic acid or methacrylic acid
  • the water-containing gel may be neutralized with a base.
  • the neutralization degree of the acid group is preferably 50 to 80 mol%. When the degree of neutralization is less than 50 mol%, the tackiness of the resulting water-containing gel polymer may be high, and the workability at the time of production and use may be deteriorated.
  • the water retention amount of the water-absorbent resin composition obtained may be reduced.
  • the degree of neutralization exceeds 80%, the pH of the obtained resin may be high, which may cause the safety of the skin of the human body.
  • the neutralization may be carried out at any stage after the polymerization of the crosslinked polymer (A) in the production of the water-absorbent resin composition, and for example, a method such as a method of neutralizing in the state of a water-containing gel is preferred. It is illustrated as As a base to be neutralized, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates such as sodium carbonate, sodium hydrogencarbonate and potassium carbonate can usually be used.
  • the water-containing gel obtained by polymerization can be shredded if necessary.
  • the size (longest diameter) of the shredded gel is preferably 50 ⁇ m to 10 cm, more preferably 100 ⁇ m to 2 cm, and particularly preferably 1 mm to 1 cm. Within this range, the drying property in the drying step is further improved.
  • the shredding can be performed by a known method, and shredding can be performed using a shredding apparatus (for example, a beck mill, a rubber chopper, a farm mill, a mincing machine, an impact crusher and a roll crusher) or the like.
  • a shredding apparatus for example, a beck mill, a rubber chopper, a farm mill, a mincing machine, an impact crusher and a roll crusher
  • the content of organic solvent and the moisture, infrared moisture measuring instrument is obtained from the weight loss of the measurement sample when heated.
  • a method of distilling off the solvent (including water) in the water-containing gel As a method of distilling off the solvent (including water) in the water-containing gel, a method of distilling (drying) with hot air at a temperature of 80 to 230 ° C., a thin film drying method by a drum dryer heated to 100 to 230 ° C. (Heating) reduced-pressure drying method, lyophilization method, infrared ray drying method, decantation and filtration can be applied.
  • a crosslinked polymer (A) After drying the water-containing gel to obtain a crosslinked polymer (A), it can be further pulverized.
  • a grinding method for example, a hammer type crusher, an impact type crusher, a roll crusher, a shet type crusher, etc.
  • the particle size of the pulverized crosslinked polymer can be adjusted by sieving, if necessary.
  • the weight-average particle size ( ⁇ m) of the cross-linked polymer (A) optionally sieved is preferably 100 to 800, more preferably 200 to 700, next preferably 250 to 600, particularly preferably 300 to 500, most preferably Preferably it is 350-450. Within this range, the absorption performance is further improved.
  • the weight-average particle size is determined using the low tap test sieve shaker and standard sieves (JIS Z8801-1: 2006) according to Perry's Chemical Engineers Handbook 6th Edition (McGrow Hill Book, Inc. 1984) , Page 21). That is, JIS standard sieves are combined in the order of 1000 ⁇ m, 850 ⁇ m, 710 ⁇ m, 500 ⁇ m, 425 ⁇ m, 355 ⁇ m, 250 ⁇ m, 150 ⁇ m, 125 ⁇ m, 75 ⁇ m and 45 ⁇ m from the top, and a pan. About 50 g of the measurement particles are placed in the uppermost sieve and shaken for 5 minutes with a low tap test sieve shaker.
  • the weight of the measurement particles on each sieve and receiver is weighed, and the weight fraction of the particles on each sieve is determined by taking the total as 100% by weight. After plotting the weight fraction on the vertical axis), a line connecting points is drawn to obtain a particle size corresponding to 50% by weight of the weight fraction, which is defined as a weight average particle size.
  • the ratio (% by weight) is preferably 3 or less, more preferably 1 or less.
  • the content of the fine particles can be determined using a graph created when determining the above-described weight average particle diameter.
  • the shape of the crosslinked polymer (A) is not particularly limited, and examples thereof include irregularly crushed, scaly, pearly and rice grains. Among these, from the viewpoint of good interlocking with the fibrous material in paper diaper applications and the like and no concern of detachment from the fibrous material, the irregularly crushed material is preferable.
  • the crosslinked polymer (A) may contain some other components such as a residual solvent and a residual crosslinking component as long as the performance is not impaired.
  • the water-absorbent resin composition of the present invention preferably has a structure in which the surface of the crosslinked polymer (A) is crosslinked by the organic surface crosslinking agent (e).
  • the organic surface crosslinking agent (e) include known polyvalent glycidyl compounds, polyvalent amines, polyvalent aziridine compounds and polyvalent isocyanate compounds described in JP-A-59-189103, JP-A-58-180233, etc.
  • polyhydric alcohols described in JP-A-61-16903 silane coupling agents described in JP-A-61-211305 and JP-A-61-252212, described in JP-A-5-508425.
  • organic surface cross-linking agents of polyvalent oxazoline compounds described in JP-A No. 11-240959, etc. can be used.
  • these surface crosslinking agents polyvalent glycidyl compounds, polyhydric alcohols and polyhydric amines are preferable from the viewpoint of economy and absorption characteristics, and polyvalent glycidyl compounds and polyhydric alcohols are more preferable, and polyvalent glycidyl compounds are more preferable.
  • Glycidyl compounds most preferably ethylene glycol diglycidyl ether.
  • the organic surface crosslinking agent (e) may be used alone or in combination of two or more.
  • the amount (% by weight) of the organic surface crosslinking agent (e) used is not particularly limited because it can be variously changed depending on the type of the surface crosslinking agent, the conditions for crosslinking, and the target performance. From the viewpoint of absorption characteristics, etc., 0.001 to 3 is preferable based on the weight of the water absorbent resin composition, more preferably 0.005 to 2, and particularly preferably 0.01 to 1.5.
  • the surface crosslinking of the crosslinked polymer (A) can be carried out by mixing the crosslinked polymer (A) and the organic surface crosslinking agent (e) and heating.
  • a mixing method of the crosslinked polymer (A) and the organic surface crosslinking agent (e) a cylindrical mixer, screw mixer, screw extruder, turbulizer, Nauta mixer, double-arm kneader, Cross-linked polymer (A) and organic using mixing equipment such as flow type mixer, V type mixer, minced mixer, ribbon type mixer, air flow type mixer, rotary disk type mixer, conical blender and roll mixer
  • the method of mixing uniformly with the surface crosslinking agent (e) is mentioned.
  • the organic surface crosslinking agent (e) may be used after being diluted with water and / or any solvent.
  • the temperature at the time of mixing the crosslinked polymer (A) and the organic surface crosslinking agent (e) is not particularly limited, it is preferably 10 to 150 ° C., more preferably 20 to 100 ° C., particularly preferably 25 to 80 ° C. is there.
  • the heating temperature is preferably 100 to 180 ° C., more preferably 110 to 175 ° C., particularly preferably 120 to 170 ° C. from the viewpoint of the breakage resistance of the resin particles.
  • the heating time can be appropriately set according to the heating temperature, but is preferably 5 to 60 minutes, more preferably 10 to 40 minutes, from the viewpoint of absorption performance. It is also possible to further crosslink the surface of the water-absorbent resin obtained by surface cross-linking, using an organic surface cross-linking agent of the same or different type as the organic surface cross-linking agent used first.
  • the particle size is adjusted by sieving as required.
  • the average particle size of the obtained particles is preferably 100 to 600 ⁇ m, more preferably 200 to 500 ⁇ m.
  • the content of the fine particles is preferably small, the content of particles of 100 ⁇ m or less is preferably 3% by weight or less, and the content of particles of 150 ⁇ m or less is more preferably 3% by weight or less.
  • the water-absorbent resin composition of the present invention contains water-insoluble alumina-containing fine particles (c).
  • the water-insoluble alumina-containing particles (c) include alumina (aluminum oxide) particles, alumina-modified silica particles, boehmite particles, aluminum hydroxide particles, aluminum phosphate particles, and aluminosilicate particles such as zeolite and montmorillonite.
  • Alumina fine particles and alumina-modified silica fine particles are preferable, and alumina-modified silica fine particles are more preferable, from the viewpoints of easy availability, easy handling, and absorption performance.
  • one type may be used alone, or two or more types may be used in combination.
  • alumina-modified silica generally refers to fine particles having a structure in which at least a portion of the surface of the fine silica particles is coated with alumina.
  • the water-insoluble alumina-containing fine particles (c) in the present invention are preferably spherical or amorphous particles having an average primary particle size of 1 to 100 nm. When the particles are spherical or amorphous, the powder flowability of the water-absorbent resin composition becomes good.
  • the average primary particle diameter of the water-insoluble alumina-containing fine particles (c) is preferably 2 to 80 nm, more preferably 3 to 60 nm, particularly preferably 5 to 50 nm, and most preferably 5 to 20 nm. If the average primary particle size is smaller than 1 nm, the absorption characteristics of the water-absorbent resin composition under load may be deteriorated.
  • the measurement of the average primary particle size of the water-insoluble alumina-containing fine particles (c) may be performed by a conventionally known method, for example, individual particles of 100 or more particles from an image of 50,000 times with a transmission electron microscope Method of measuring the particle diameter from the average of the longest diameter and the shortest diameter of the particle to obtain the average value, a method using a scattering type particle size distribution measuring apparatus using dynamic light scattering or laser diffraction method, or spherical particles The method etc. which are calculated from the specific surface area by BET method are mentioned. When using a commercial item, its catalog value can be substituted.
  • the water-absorbent resin composition of the present invention can be obtained by mixing the crosslinked polymer (A) and the water-insoluble alumina-containing fine particles (c).
  • a mixing method a cylindrical mixer, a screw mixer, a screw extruder, a turbulizer, a Nauta mixer, a double arm kneader, a fluid mixer, a V mixer, a mince mixer, a ribbon type
  • the method include uniform mixing using known mixing devices such as mixers, air-flow mixers, rotary disk mixers, conical blenders and roll mixers.
  • the water-insoluble alumina-containing fine particles (c) may be added simultaneously with the water and / or the solvent.
  • a dispersion in which water-insoluble alumina-containing fine particles (c) are dispersed in water and / or a solvent can be added. From the viewpoint, it is preferable to add a dispersion, and it is more preferable to add an aqueous dispersion. When adding a dispersion, it is preferable to add by spraying or dripping.
  • the content of water-insoluble alumina-containing microparticles (c) in the dispersion is preferably 5 to 70% by weight based on the total weight of the dispersion, More preferably, it is 10 to 60% by weight.
  • the dispersion of the water-insoluble alumina-containing fine particles (c) may be a dispersion obtained by directly granulating the raw material in water and / or a solvent according to a method known in the prior art, and A dispersion obtained by mechanical dispersion in a solvent may be used. From the viewpoint of the stability of the dispersion, it is preferable to use a dispersion obtained by directly granulating the raw material in water and / or a solvent and granulating it.
  • a dispersion of the water-insoluble alumina-containing fine particles (c) can be obtained as a commercial colloidal liquid (sol).
  • the dispersion may contain, if necessary, additives such as any stabilizer.
  • the stabilizer examples include commercially available surfactants and dispersants, commercially available acid compounds [phosphoric acid (salt), boric acid (salt), alkali metal (salt) and alkaline earth metal (salt), hydroxy carbon Acids (salts), fatty acids (salts), etc.] can be mentioned.
  • the temperature when mixing the crosslinked polymer (A) and the water-insoluble alumina-containing fine particles (c) is preferably 10 to 150 ° C., more preferably 20 to 100 ° C., particularly preferably 25 to 80 ° from the viewpoint of absorption performance. ° C.
  • the heating temperature is preferably 25 to 180 ° C., more preferably 30 to 175 ° C., particularly preferably 35 to 170 ° C. from the viewpoint of the breakage resistance of the resin particles.
  • heating at 180 ° C. or lower indirect heating using steam is possible, which is advantageous in equipment.
  • the water and the solvent to be used in combination may be excessively left in the water absorbent resin, and the absorption performance may be deteriorated.
  • the amount of water and solvent remaining in the water-absorbent resin is preferably 1 to 10 parts by weight per 100 parts by weight of the water-absorbent resin.
  • the amount of water and solvent remaining in the water-absorbent resin can be obtained by a heating loss method in accordance with JIS K 0067-1992 (Method for testing weight loss and residue of chemical products).
  • the heating time can be appropriately set by the heating temperature, but from the viewpoint of absorption performance, preferably 5 to 60 minutes, More preferably, it is 10 to 40 minutes.
  • the water-absorbent resin composition of the present invention may be sieved to adjust the particle size after mixing the crosslinked polymer (A) and the water-insoluble alumina-containing fine particles (c).
  • the average particle size of the particles obtained by adjusting the particle size is preferably 100 to 600 ⁇ m, more preferably 200 to 500 ⁇ m.
  • the content of the fine particles is preferably small, the content of particles of 100 ⁇ m or less is preferably 3% by weight or less, and the content of particles of 150 ⁇ m or less is more preferably 3% by weight or less.
  • the content of the water-insoluble alumina-containing fine particles (c) can be adjusted according to the application of the water-absorbent resin composition, but based on the weight of the crosslinked polymer (A).
  • 0.01 to 1% by weight is preferable, more preferably 0.02 to 0.8% by weight, and particularly preferably 0.05 to 0.5% by weight.
  • the liquid permeability of the water-absorbent resin composition becomes good, which is further preferable.
  • the water absorbent resin composition of the present invention contains a water soluble aluminum salt (d).
  • water-soluble aluminum salts (d) include aluminates (sodium aluminate, potassium aluminate, and hydrates thereof, etc.), sulfates of aluminum and double salts thereof (aluminum sulfate, potassium aluminum sulfate, sodium aluminum sulfate) And their hydrates], chlorides of aluminum [aluminium chloride, polyaluminium chloride, and hydrates thereof], and organic acid salts of aluminum [aluminium lactate, aluminum acetate, and hydrates thereof] Etc.
  • One kind of (d) may be used alone, or two or more kinds may be used in combination.
  • the water-soluble aluminum salt (d) in the present invention is preferably a crystalline salt having a water solubility of 10 g / 100 g H 2 O or more at 20 ° C.
  • the water solubility of the water-soluble aluminum salt (d) is more preferably 20 g / 100 g H 2 O or more, still more preferably 25 g / 100 g H 2 O or more.
  • the water solubility is smaller than 10 g / 100 g H 2 O, uniform mixing with the crosslinked polymer (A) is difficult, and the liquid permeability of the water-absorbent resin composition is deteriorated.
  • (d) is non-crystalline, elution of the aluminum water-soluble salt easily occurs at the time of swelling of the water-absorbent resin, and the absorption performance is deteriorated. Therefore, (d) is preferably crystalline. If (d) is a highly water-soluble crystalline salt, the surface of the water-absorbent resin is likely to be coated with microcrystalline aluminum water-soluble salt, and the liquid permeability is particularly excellent.
  • water-soluble aluminum salts (d) aluminum sulfates and double salts thereof are preferred from the viewpoint of high crystallinity and high water solubility and easy availability, aluminum sulfate 14-18 hydrate and aluminum sodium sulfate More preferred is dodecahydrate.
  • the water-absorbent resin composition of the present invention can be obtained by mixing the crosslinked polymer (A) and the water-soluble aluminum salt (d).
  • a mixing method a cylindrical mixer, a screw mixer, a screw extruder, a turbulizer, a Nauta mixer, a double arm kneader, a fluid mixer, a V mixer, a mince mixer, a ribbon type
  • the method include uniform mixing using known mixing devices such as mixers, air-flow mixers, rotary disk mixers, conical blenders and roll mixers.
  • the water-soluble aluminum salt (d) In mixing the crosslinked polymer (A) and the water-soluble aluminum salt (d), it is preferable to add the water-soluble aluminum salt (d) while stirring the crosslinked polymer (A).
  • the water-soluble aluminum salt (d) to be added may be added simultaneously with the water and / or the solvent.
  • a solution of water-soluble aluminum salt (d) dissolved in water and / or solvent is added from the viewpoint of workability and liquid permeability. It is further preferred to add an aqueous solution dissolved in a solvent containing water.
  • the content of the water-soluble aluminum salt (d) contained in the solution is preferably 5 to 70% by weight based on the total weight of the solution, more preferably 10 to It is 60% by weight.
  • the temperature at which the cross-linked polymer (A) and the water-soluble aluminum salt (d) are mixed is not particularly limited, but is preferably 10 to 150 ° C., more preferably 20 to 100 ° C., particularly preferably 25 to 80 ° C. .
  • the heating temperature is preferably 25 to 180 ° C., more preferably 30 to 175 ° C., particularly preferably 35 to 170 ° C. from the viewpoint of the breakage resistance of the resin particles.
  • the heating temperature is preferably 25 to 180 ° C., more preferably 30 to 175 ° C., particularly preferably 35 to 170 ° C. from the viewpoint of the breakage resistance of the resin particles.
  • indirect heating using steam is possible, which is advantageous in equipment.
  • the water and the solvent to be used in combination may be excessively left in the water absorbent resin, and the absorption performance may be deteriorated.
  • the amount of water and solvent remaining in the water-absorbent resin is preferably 1 to 10 parts by weight per 100 parts by weight of the water-absorbent resin.
  • the amount of water and solvent remaining in the water-absorbent resin can be obtained by a heating loss method in accordance with JIS K 0067-1992 (Method for testing weight loss and residue of chemical products).
  • the heating time can be appropriately set according to the heating temperature, but from the viewpoint of absorption performance, preferably 5 to 60 minutes, further Preferably, it is 10 to 40 minutes.
  • a water-absorbent resin obtained by mixing a crosslinked polymer (A) and a water-soluble aluminum salt (d) is further surface-treated with a water-soluble aluminum salt of the same or different type as the water-soluble aluminum salt used first. It is also possible.
  • the water-absorbent resin composition of the present invention may be sieved to adjust the particle size after mixing the crosslinked polymer (A) and the water-soluble aluminum salt (d).
  • the average particle size of the particles obtained by adjusting the particle size is preferably 100 to 600 ⁇ m, more preferably 200 to 500 ⁇ m.
  • the content of the fine particles is preferably small, the content of particles of 100 ⁇ m or less is preferably 3% by weight or less, and the content of particles of 150 ⁇ m or less is more preferably 3% by weight or less.
  • the content of the water-soluble aluminum salt (d) can be adjusted according to the application of the water-absorbent resin composition, but based on the weight of the crosslinked polymer (A). 0.05 to 5% by weight, more preferably 0.1 to 4% by weight, and particularly preferably 0.2 to 3% by weight. Within this range, the liquid permeability of the water-absorbent resin composition becomes good, which is further preferable.
  • water-soluble aluminum salt (d) is a hydrate, it is based on the mass except hydration water.
  • the water-absorbent resin composition of the present invention can be obtained by mixing the crosslinked polymer (A) with the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d). (C) and the water-soluble aluminum salt (d) may be added simultaneously or separately to the crosslinked polymer (A). It is preferable to simultaneously add from the viewpoint of coating uniformity and liquid permeability.
  • the simultaneous addition means that they are added at one time or separately in each step such as the above-mentioned drying, grinding, surface crosslinking and the like.
  • the surface of the crosslinked polymer (A) has a structure crosslinked by the organic surface crosslinking agent (e), the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d)
  • the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) are preferably added simultaneously with or before the addition of the organic surface crosslinking agent (e), and at least one of the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) is organically crosslinked
  • the surface aluminum coverage of the crosslinked polymer (A) is 60 to 100%.
  • the surface aluminum coverage is preferably 65 to 100%, more preferably 70 to 100%, and particularly preferably 75 to 100%, from the viewpoints of blocking resistance and liquid permeability and gel strength in initial swelling.
  • the addition amount of the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) can be adjusted to the above-mentioned range.
  • the surface aluminum coverage is an index showing the coating state by the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) and can be measured by aluminum element mapping using energy dispersive X-ray analysis described later. .
  • the water-absorbent resin composition of the present invention may further contain a polyhydric alcohol (f) having 4 or less carbon atoms.
  • a polyhydric alcohol (f) having 4 or less carbon atoms include ethylene glycol, propylene glycol, 1,3-propanediol, glycerin, 1,4-butanediol and the like. Among these, propylene glycol and glycerin are preferable in terms of safety and availability, and propylene glycol is more preferable.
  • one type may be used alone, or two or more types may be used in combination.
  • the amount (% by weight) of the polyhydric alcohol (f) having 4 or less carbon atoms is preferably 0.05 to 5 based on the weight of the crosslinked polymer (A) from the viewpoint of absorption performance and liquid permeability. It is preferably 0.1 to 3, particularly preferably 0.2 to 2.
  • the polyhydric alcohol (f) having 4 or less carbon atoms When the polyhydric alcohol (f) having 4 or less carbon atoms is contained, it may be added in any step, but from the viewpoint of liquid permeability, addition simultaneously with the water-soluble aluminum salt (d) is more preferable, and water insoluble It is particularly preferable to simultaneously add the alumina-containing fine particles (c), the water-soluble aluminum salt (d) and the organic surface crosslinking agent (e).
  • the deposition rate of the water-soluble aluminum salt (d) on the surface of the water-absorbent resin can be controlled, and the coverage and liquid permeability are improved.
  • the water absorbent resin composition of the present invention may further contain a hydrophobic substance (g).
  • the hydrophobic substance (g) includes a hydrophobic substance containing a hydrocarbon group (g1), a hydrophobic substance containing a hydrocarbon group having a fluorine atom (g2), and a hydrophobic substance having a polysiloxane structure (g3) Etc. are included.
  • hydrophobic substance (g1) containing a hydrocarbon group polyolefin resin, polyolefin resin derivative, polystyrene resin, polystyrene resin derivative, wax, long chain fatty acid ester, long chain fatty acid and salts thereof, long chain aliphatic alcohol, long And chain aliphatic amides and mixtures of two or more thereof.
  • the weight of the polyolefin resin is an olefin having 2 to 4 carbon atoms ⁇ ethylene, propylene, isobutylene, isoprene, etc. ⁇ as an essential constituent monomer (the content of the olefin is at least 50% by weight based on the weight of the polyolefin resin)
  • Polymers having an average molecular weight of 1,000 to 1,000,000 eg, polyethylene, polypropylene, polyisobutylene, poly (ethylene-isobutylene) and isoprene etc.
  • a polyolefin resin derivative a polymer having a weight average molecular weight of 1000 to 1,000,000 obtained by introducing a carboxy group (-COOH), 1,3-oxo-2-oxapropylene (-COCOO-) or the like into a polyolefin resin ⁇ eg polyethylene heat Degradation body, polypropylene thermal degradation body, maleic acid modified polyethylene, chlorinated polyethylene, maleic acid modified polypropylene, ethylene-acrylic acid copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, maleated And polybutadiene, ethylene-vinyl acetate copolymer, and maleated ethylene-vinyl acetate copolymer, etc. ⁇ .
  • polystyrene resin a polymer having a weight average molecular weight of 1,000 to 1,000,000 can be used.
  • polystyrene resin derivative a polymer having a weight average molecular weight of 1000 to 1,000,000 and a polymer having a weight average molecular weight of 1000 to 1,000,000, in which styrene is an essential constituent monomer (the content of styrene is at least 50% by weight based on the weight of the polystyrene derivative) And maleic anhydride copolymer, styrene-butadiene copolymer, and styrene-isobutylene copolymer.
  • Waxes include waxes having a melting point of 50 to 200 ° C. (eg, paraffin wax, beeswax, carbana wax, tallow, etc.).
  • esters of fatty acids having 8 to 30 carbon atoms and alcohols having 1 to 12 carbon atoms ⁇ eg methyl laurate, ethyl laurate, methyl stearate, ethyl stearate, methyl oleate, oleic acid Ethyl, glycerine laurate monoester, glycerine stearate monoester, glycerine oleate monoester, pentaerythritol dilaurate monoester, pentaerythritol stearate monoester, pentaerythritol oleate monoester, sorbit laurate monoester, Sorbit stearic acid monoester, Sorbit oleic acid monoester, Sucrose palmitic acid monoester, Sucrose palmitic acid diester, Sucrose palmitic acid triester, Sucrose stearic acid moester
  • long chain fatty acids and salts thereof include fatty acids having 8 to 30 carbon atoms (eg, lauric acid, palmitic acid, stearic acid, oleic acid, dimer acid and behenic acid etc.), and salts thereof include zinc, calcium, Salts with magnesium or aluminum (hereinafter abbreviated as Zn, Ca, Mg and Al, respectively) ⁇ eg, Ca palmitate, Al palmitate, Ca stearate, Mg stearate, Al stearate etc. ⁇ can be mentioned.
  • fatty acids having 8 to 30 carbon atoms eg, lauric acid, palmitic acid, stearic acid, oleic acid, dimer acid and behenic acid etc.
  • salts thereof include zinc, calcium, Salts with magnesium or aluminum (hereinafter abbreviated as Zn, Ca, Mg and Al, respectively) ⁇ eg, Ca palmitate, Al palmitate, Ca stearate, Mg stearate, Al stearate etc. ⁇ can be
  • the long chain aliphatic alcohol includes aliphatic alcohols having 8 to 30 carbon atoms (eg, lauryl alcohol, palmityl alcohol, stearyl alcohol, oleyl alcohol etc.). From the viewpoint of moisture resistance of the absorbent article, palmityl alcohol, stearyl alcohol and oleyl alcohol are preferable, and stearyl alcohol is more preferable.
  • an amidated compound of a long chain aliphatic primary amine having 8 to 30 carbon atoms and a carboxylic acid having a hydrocarbon group having 1 to 30 carbon atoms, ammonia, or a primary amine having 1 to 7 carbon atoms Amidated with a long chain fatty acid having 8 to 30 carbon atoms, an amidated long chain aliphatic secondary amine having at least one aliphatic chain having 8 to 30 carbon atoms and a carboxylic acid having 1 to 30 carbon atoms,
  • An amidated product of a secondary amine having two aliphatic hydrocarbon groups having 1 to 7 carbon atoms and a long chain fatty acid having 8 to 30 carbon atoms can be mentioned.
  • amidated compound of a long-chain aliphatic primary amine having 8 to 30 carbon atoms and a carboxylic acid having a hydrocarbon group having 1 to 30 carbon atoms one obtained by reacting a primary amine and a carboxylic acid at a ratio of 1 to 1 : It is divided into the thing which reacted by 2.
  • a product reacted at 1: 1 acetic acid N-octylamide, acetic acid N-hexacosylamide, heptacosanoic acid N-octylamide, heptacosanoic acid N-hexacosylamide and the like can be mentioned.
  • Examples of the reaction at 1: 2 include diacetic acid N-octylamide, diacetic acid N-hexacosylamide, diheptacosanic acid N-octylamide, and diheptacosanic acid N-hexacosylamide.
  • the primary amine and the carboxylic acid are reacted at 1: 2, the carboxylic acids used may be the same or different.
  • the amidated product of ammonia or a primary amine having 1 to 7 carbon atoms and a long chain fatty acid having 8 to 30 carbon atoms the product obtained by reacting ammonia or a primary amine with carboxylic acid in a ratio of 1: 1 can be used. It is divided into the reaction products.
  • a product reacted at 1: 1 nonanoic acid amide, nonanoic acid methylamide, nonanoic acid N-heptylamide, heptacosanoic acid amide, heptacosanoic acid N-methylamide, heptacosanoic acid N-heptylamide and heptacosanoic acid N-hexacosylamide Etc.
  • Examples of the amidated compound of a long chain aliphatic secondary amine having at least one aliphatic chain having 8 to 30 carbon atoms and a carboxylic acid having 1 to 30 carbon atoms include acetic acid N-methyloctylamide and acetic acid N-methylhexaco Luamide, acetic acid N-octylhexacosylamide, acetic acid N-dihexacosylamide, heptacosanoic acid N-methyloctylamide, heptacosanoic acid N-methylhexacosylamide, heptacosanoic acid N-octylhexacosylamide and heptacosane Acid N-dihexacosylamide and the like.
  • nonanoic acid N-dimethylamide nonanoic acid N-methylheptylamide
  • Nonanoic acid N-diheptylamide, heptacosanoic acid N-dimethylamide, heptacosanoic acid N-methylheptylamide, heptacosanoic acid N-diheptylamide and the like can be mentioned.
  • hydrophobic substance (g2) containing a hydrocarbon group having a fluorine atom perfluoroalkanes, perfluoroalkenes, perfluoroaryls, perfluoroalkylethers, perfluoroalkylcarboxylic acids, perfluoroalkylalcohols and two of them Mixtures of species or more are included.
  • hydrophobic substance (g3) having a polysiloxane structure examples include polydimethylsiloxane, polyether-modified polysiloxane ⁇ polyoxyethylene-modified polysiloxane and poly (oxyethylene ⁇ oxypropylene) -modified polysiloxane etc. ⁇ , carboxy-modified polysiloxane, Epoxy-modified polysiloxane, amino-modified polysiloxane, alkoxy-modified polysiloxane and the like and mixtures thereof are included.
  • the HLB value of the hydrophobic substance (g) is preferably 1 to 10, more preferably 2 to 8, and particularly preferably 3 to 7. Within this range, the blocking resistance at the time of initial swelling is further improved.
  • the HLB value means the hydrophilic-hydrophobic balance (HLB) value, and can be determined by the Oda method (new surfactant introduction, page 197, published by Takehiko Fujimoto, Sanyo Chemical Industries, Ltd., published in 1981). .
  • hydrophobic substances (g1) containing a hydrocarbon group are preferable, and long chain fatty acid esters, long chain fatty acids and salts thereof, Long-chain aliphatic alcohols and long-chain aliphatic amides, more preferably Sorbit stearic acid ester, sucrose stearic acid ester, stearic acid, stearic acid Mg, stearic acid Ca, stearic acid Zn and stearic acid Al, particularly preferably Sucrose stearate and Mg stearate, most preferably sucrose stearate.
  • the amount (% by weight) of the hydrophobic substance (g) is preferably 0.001 to 1 based on the weight of the crosslinked polymer (A) from the viewpoint of absorption performance and blocking resistance at the time of initial swelling, more preferably Is from 0.005 to 0.5, particularly preferably from 0.01 to 0.3.
  • the hydrophobic substance (g) When the hydrophobic substance (g) is contained, it may be added in any step, but is added prior to the addition of the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) from the viewpoint of absorption performance.
  • the hydrophobic substance (g) is preferably the surface crosslinked by the organic surface crosslinking agent (e). More preferably it is added before.
  • the water-absorbent resin composition of the present invention may contain, if necessary, additives (for example, known preservatives (described in JP-A 2003-225565 and JP-A 2006-131767) and the like, fungicides, antibacterial agents, Antioxidants, UV absorbers, colorants, fragrances, deodorants, liquid flow improvers, organic fibrous materials and the like can also be included.
  • additives for example, known preservatives (described in JP-A 2003-225565 and JP-A 2006-131767) and the like, fungicides, antibacterial agents, Antioxidants, UV absorbers, colorants, fragrances, deodorants, liquid flow improvers, organic fibrous materials and the like can also be included.
  • the content (% by weight) of the additive is preferably 0.001 to 10, more preferably 0.01 to 5, particularly preferably 0.01 to 5 based on the weight of the crosslinked polymer (A).
  • it is 0.05 to 1, most preferably 0.1 to 0.5.
  • the crosslinked polymer (A) is surface-treated using an aqueous colloidal solution of water-insoluble alumina-containing fine particles (c) and an aqueous solution of a water-soluble aluminum salt (d), and then surface cross-linked.
  • aqueous colloidal solution of the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) are as described above.
  • an aqueous colloid solution of water-insoluble alumina-containing fine particles (c), a water-soluble aluminum salt (d) It is further preferable to carry out heat treatment after simultaneously adding the aqueous solution of (a), the organic surface crosslinking agent (e) and the polyhydric alcohol having 4 or less carbon atoms.
  • the water retention amount (g / g) of the water-absorbent resin composition of the present invention and the water-absorbent resin composition obtained by the production method of the present invention (hereinafter referred to as the water-absorbent resin composition of the present invention without distinction) It can be measured by the method described later and is preferably 28 or more, more preferably 33 or more, and still more preferably 35 or more from the viewpoint of the amount of absorption of diapers.
  • the upper limit is preferably 60 or less, more preferably 55 or less, and still more preferably 50 or less from the viewpoint of the amount of absorption under load.
  • the water retention amount can be appropriately adjusted by the amount (% by weight) of the crosslinking agent (b) and the organic surface crosslinking agent (e).
  • the gel flow rate (ml / min) of the water-absorbent resin composition of the present invention can be measured by the method described later, and is preferably 5 to 300 from the viewpoint of diaper absorption rate, and 10 to 280 is more preferable. Preferred and particularly preferred is 15 to 250. It is empirically known that the gel flow rate is contrary to the water retention amount, and there are cases where a high water retention amount is required or a high gel flow rate is required depending on the configuration of the diaper.
  • the apparent density (g / ml) of the water-absorbent resin composition of the present invention is preferably 0.50 to 0.80, more preferably 0.52 to 0.75, particularly preferably 0.54 to 0.70. is there. When it is in this range, the anti-crash resistance of the absorbent article is further improved.
  • the apparent density of the water absorbing resin composition is measured at 25 ° C. in accordance with JIS K7365: 1999.
  • the blocking ratio at the initial swelling of the water-absorbent resin composition of the present invention is preferably 0 to 50%, more preferably 0 to 40%, and particularly preferably 0 to 30%. Within this range, the liquid diffusivity is sufficiently ensured in the absorber, and the absorption performance is stabilized.
  • the gel strength (kN / m 2 ) of the water-absorbent resin composition of the present invention is preferably 2.5 or more, more preferably 2.7 or more. Within this range, the liquid permeability under load is sufficiently ensured, and the absorption performance is stabilized.
  • An absorbent can be obtained using the water-absorbent resin composition of the present invention.
  • a water-absorbent resin composition may be used alone, or may be used as an absorber together with other materials.
  • Other materials include fibrous materials and the like.
  • the structure, manufacturing method and the like of the absorber when used together with the fibrous material are the same as those of known ones (Japanese Patent Application Laid-Open Nos. 2003-225565, 2006-131767 and 2005-097569, etc.) is there.
  • Preferred as the fibrous material are cellulose fibers, organic synthetic fibers, and a mixture of cellulose fibers and organic synthetic fibers.
  • cellulosic fibers include natural fibers such as fluff pulp, and cellulosic chemical fibers such as viscose rayon, acetate and cupra.
  • natural fibers such as fluff pulp
  • cellulosic chemical fibers such as viscose rayon, acetate and cupra.
  • organic synthetic fibers include polypropylene fibers, polyethylene fibers, polyamide fibers, polyacrylonitrile fibers, polyester fibers, polyvinyl alcohol fibers, polyurethane fibers and heat fusible composite fibers (the above-mentioned fibers having different melting points) Fibers in which at least two of them are combined with a sheath-core type, eccentric type, parallel type, etc., fibers obtained by blending at least two of the above fibers, and fibers obtained by modifying the surface layer of the above fibers).
  • fibrous materials preferred are cellulose-based natural fibers, polypropylene-based fibers, polyethylene-based fibers, polyester-based fibers, heat-sealable composite fibers and mixed fibers thereof, and more preferred are fibers obtained It is a fluff pulp, a heat-fusible composite fiber, and a mixed fiber thereof in that it is excellent in the shape-retaining property after water absorption of the water-absorbing agent.
  • the length and thickness of the fibrous material are not particularly limited, and can be suitably used if the length is in the range of 1 to 200 mm and the thickness is in the range of 0.1 to 100 denier.
  • the shape is also not particularly limited as long as it is fibrous, and thin cylindrical, split yarn, staple, filament, web and the like are exemplified.
  • the weight ratio of the water-absorbent resin composition to the fibers is preferably 40/60 to 90/10. More preferably, it is 70/30 to 80/20.
  • An absorbent article can be obtained using the water absorbent resin of the present invention. Specifically, the above-mentioned absorber is used.
  • the absorbent articles are applicable not only to sanitary goods such as disposable diapers and sanitary napkins, but also to various uses such as absorption of various aqueous liquids to be described later, use as a holding agent, use as a gelling agent, and the like.
  • the method for producing the absorbent article and the like are the same as known ones (described in JP-A-2003-225565, JP-A-2006-131767 and JP-A-2005-097569).
  • ⁇ Method of measuring absorption under load> In a cylindrical plastic tube (inner diameter: 25 mm, height: 34 mm) having a nylon mesh of 63 ⁇ m (JIS Z8801-1: 2006) attached to the bottom, 250 to 500 ⁇ m using a 30 mesh sieve and a 60 mesh sieve After weighing 0.16 g of the measurement sample sifted into a range and arranging the cylindrical plastic tube vertically so that the measurement sample has a substantially uniform thickness on a nylon mesh, a weight (weight: 210.6 g, outer diameter: 24.5 mm,).
  • a pressure shaft 9 (weight) in which a circular wire mesh 8 (150 ⁇ m mesh, 25 mm diameter) is vertically bonded to the surface of the swollen gel particles 2 22 g, 47 cm in length, was placed so that the wire mesh and the swollen gel particles were in contact with each other, and further, a weight 10 (88.5 g) was placed on the pressure shaft 9 and allowed to stand for 1 minute.
  • the cock 7 is opened, and the time (T1; seconds) required for the liquid level in the filtration cylinder to change from 60 ml division line 4 to 40 ml division line 5 is measured, and gel flow rate (ml / min) I asked for.
  • ⁇ Method of measuring surface aluminum coverage Fix 10 samples or more of the measurement sample sieved in the range of 250 to 500 ⁇ m using a 30 mesh sieve and a 60 mesh sieve on a sample stand with a carbon tape so that the particles do not overlap with each other. It was set in a JEOL field emission scanning electron microscope “JSM-7000” attached with a line analysis (EDS analysis) apparatus. The magnification was increased by 150 times, one particle was displayed on the screen, and EDS analysis was performed in the elemental mapping mode.
  • the detection area of aluminum which is the target element is S1
  • the detection area of the feature element of the water-absorbent resin composition sodium when the main component of the water-absorbent resin composition is polyacrylic acid sodium salt
  • the detection area is S0.
  • Example 1 Acrylic acid (a1-1) ⁇ Mitsubishi Chemical Co., Ltd., purity 100% ⁇ 131 parts, Crosslinking agent (b-1) ⁇ pentaerythritol triallyl ether, 0.40 parts of Diso-Ltd. ⁇ , deionized water 362 The part was kept at 3 ° C. with stirring and mixing. After nitrogen is introduced into this mixture to make the amount of dissolved oxygen 1 ppm or less, 0.5 part of 1% aqueous hydrogen peroxide solution, 1 part of 2% aqueous ascorbic acid solution and 2% 2,2'-azobisamidinopropane One part of aqueous dihydrochloride solution was added and mixed to initiate polymerization. After the temperature of the mixture reached 80 ° C., a hydrogel was obtained by polymerizing at 80 ⁇ 2 ° C. for about 5 hours.
  • the water-absorbent resin composition (P-1) was obtained.
  • Example 2 While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c) Al-L7 (made by Taki Chemical Co., Ltd.) 4.0 parts as ethylene, 0.1 part of ethylene glycol diglycidyl ether as organic surface crosslinking agent (e), as polyhydric alcohol having 4 or less carbon atoms (f) A mixed solution of 0.5 parts of propylene glycol and 1.1 parts of water, and 0.6 parts of sodium aluminum sulfate dodecahydrate as a water-soluble aluminum salt (d), and a polyhydric alcohol having 4 or less carbon atoms A mixed solution of 0.5 parts of propylene glycol as (f) and 1.4 parts of water is simultaneously added, uniformly mixed, and then heated at 130 ° C.
  • Example 3 While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c) Al-C20 (manufactured by Taki Chemical Co., Ltd.) as 1.5 parts, ethylene part diglycidyl ether as an organic surface crosslinking agent (e) 0.1 parts, as a polyhydric alcohol having 4 or less carbon atoms (f) Mixed liquid of 0.8 parts of propylene glycol and 1.3 parts of water, and 0.6 parts of sodium aluminum sulfate dodecahydrate as water-soluble aluminum salt (d), polyhydric alcohol having 4 or less carbon atoms A mixed solution of 0.5 parts of propylene glycol as (f) and 1.4 parts of water is simultaneously added, mixed uniformly, and then heated at 130 ° C. for 30 minutes to obtain To give a water absorbent resin composition (P-3). ⁇ Proper
  • Example 4 While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c) 3.0 parts of Vyral AS-L10 (manufactured by Taki Chemical Co., Ltd.), 0.1 parts of ethylene glycol diglycidyl ether as an organic surface crosslinking agent (e), and a polyhydric alcohol having 4 or less carbon atoms (f) A mixed solution of 0.5 parts of propylene glycol and 1.1 parts of water, and 0.6 parts of sodium aluminum sulfate dodecahydrate as a water-soluble aluminum salt (d), and a polyhydric alcohol having 4 or less carbon atoms A mixed solution of 0.5 parts of propylene glycol as (f) and 1.4 parts of water is simultaneously added, mixed uniformly, and then heated at 130 ° C. for 30 minutes to obtain To give a water absorbent
  • Example 5 While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c) 1.0 part of LUDOX CL (manufactured by Sigma Aldrich Japan Co., Ltd.) as a component, 0.1 part of ethylene glycol diglycidyl ether as an organic surface crosslinking agent (e), propylene as a polyhydric alcohol having 4 or less carbon atoms (f) A mixed solution of 1.0 part of glycol and 1.6 parts of water is added, mixed uniformly, heated at 130 ° C.
  • high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm fine particles containing water-insoluble alumina
  • c 1.0 part of LUDOX CL (manufactured by Sigma Aldrich Japan Co., Ltd.) as a component
  • e
  • Example 6 While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c) 0.75 parts of LUDOX CL-P (Grace Corporation) as a component, 0.1 parts of ethylene glycol diglycidyl ether as an organic surface crosslinking agent (e), propylene glycol as a polyhydric alcohol having 4 or less carbon atoms (f) A mixed solution of 1.0 part and 1.6 parts of water, 0.6 part of sodium aluminum sulfate dodecahydrate as water-soluble aluminum salt (d), polyhydric alcohol having 4 or less carbon atoms (f) The mixed solution of 0.5 parts of propylene glycol as a mixture and 1.4 parts of water is simultaneously added, mixed uniformly, and then heated at 130 ° C.
  • Comparative Example 1 A water-soluble aluminum salt (d) was added to 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 while stirring at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm). 1.2 parts of sodium aluminum sulfate dodecahydrate, 0.1 parts of ethylene glycol diglycidyl ether as organic surface crosslinking agent (e), propylene glycol as a polyhydric alcohol having 4 or less carbon atoms (f). A mixed solution of 5 parts and 1.1 parts of water was added and uniformly mixed, followed by heating at 130 ° C. for 30 minutes to obtain a water-absorbent resin composition (R-1) for comparison.
  • R-1 water-absorbent resin composition
  • Comparative Example 2 While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c 1.0 part of LUDOX CL (manufactured by Sigma Aldrich Japan Co., Ltd.), 0.1 part of ethylene glycol diglycidyl ether as organic surface crosslinking agent (e), and polyhydric alcohol having 4 or less carbon atoms (f) A mixed solution of 1.0 part of propylene glycol and 1.6 parts of water is added and uniformly mixed, and then heated at 130 ° C. for 30 minutes to obtain a water-absorbent resin composition (R-2) for comparison Obtained.
  • R-2 water-absorbent resin composition
  • Example 3 Except that, in Example 1, 1.0 part of LUDOX CL (manufactured by Sigma Aldrich Japan Co., Ltd.) as water-insoluble alumina-containing fine particles (c) is changed to 1.0 part of LUDOX HS-30 (manufactured by Sigma Aldrich Japan Co., Ltd.) In the same manner as in Example 1, a water-absorbent resin composition (R-3) for comparison was obtained.
  • the water-absorbent resin composition of the present invention is high in blocking resistance, liquid permeability and gel strength in initial swelling, and therefore, when applied to various absorbers, it has a large amount of absorption and is excellent in reversion and surface dry feeling.
  • Paper diapers such as children's paper diapers and adult paper diapers
  • napkins such as sanitary napkins
  • paper towels such as incontinent pads and surgical under pads
  • pet sheets It is suitably used for sanitary products such as (pet urine absorbing sheet) and is particularly suitable for disposable diapers.
  • the water-absorbent resin composition of the present invention is not only used for sanitary products but also for pet urine absorbents, urine gelling agents for portable toilets, freshness maintenance agents such as fruits and vegetables, drip absorbers for meats and fishes and shellfishes, disposables It is useful also for various uses, such as thermal insulation, a gelling agent for batteries, a water retention agent such as plants and soils, an anti-condensing agent, a water blocking material and a packing material, and artificial snow.

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Abstract

Provided is a water-absorbing resin which, in the initial stage of swelling, has excellent blocking resistance and which is excellent in terms of liquid passability through swollen gel particles and water absorption performance under load. The present invention relates to a water-absorbing resin composition which comprises: a crosslinked polymer (A) comprising a water-soluble vinyl monomer (a1) and/or a vinyl monomer (a2), which becomes the water-soluble vinyl monomer (a1) upon hydrolysis, and a crosslinking agent (b) as essential constituent units; water-insoluble alumina-containing fine particles (c); and a water-soluble aluminum salt (d). The crosslinked polymer (A) has a degree of surface coverage with aluminum of 60-100%.

Description

吸水性樹脂組成物及びその製造方法Water-absorbent resin composition and method for producing the same
　本発明は吸水性樹脂組成物及びその製造方法に関する。 The present invention relates to a water absorbent resin composition and a method for producing the same.
　紙おむつ、生理用ナプキン、失禁パット等の衛生材料には、パルプ等の親水性繊維とアクリル酸（塩）等とを主原料とする吸水性樹脂が吸収体として幅広く利用されている。近年のＱＯＬ（Ｑｕａｌｉｔｙ　Ｏｆ　Ｌｉｆｅ）向上の観点からこれら衛生材料はより軽量かつ薄型のものへと需要が遷移しており、これに伴って親水性繊維の使用量低減が望まれるようになってきた。そのため、これまで親水性繊維が担ってきた吸収体中での液拡散性や初期吸収の役割を吸水性樹脂それ自体に求められるようになり、加重下での吸液性及び膨潤したゲル間の通液性の高い吸水性樹脂が必要とされるようになった。 BACKGROUND OF THE INVENTION In sanitary materials such as paper diapers, sanitary napkins, incontinence pads, etc., a water absorbent resin mainly composed of hydrophilic fibers such as pulp and acrylic acid (salt) is widely used as an absorbent. From the viewpoint of improving Quality of Life (QOL) in recent years, the demand for these sanitary materials has shifted to lighter and thinner ones, and along with this, it has become desirable to reduce the amount of hydrophilic fibers used. . Therefore, it becomes possible for the water absorbent resin itself to be required to play the role of liquid diffusibility and initial absorption in the absorbent which the hydrophilic fiber has hitherto played, and it is possible to absorb the liquid under load and between the swollen gel A highly water-absorbent resin having high liquid permeability has been required.
　膨潤ゲル間の通液性を向上させる手法として、吸水性樹脂の表面を架橋することにより吸水性樹脂表面の架橋密度を高め、膨潤ゲル表面の変形を抑制し、ゲル間隙を効率的に形成する方法が既に知られている（例えば、特許文献１参照）。しかしながら表面架橋だけでは膨潤ゲル間の通液性は十分満足いくものではなかった。 As a method to improve the liquid permeability between the swelling gels, the crosslink density of the water absorbing resin surface is increased by crosslinking the surface of the water absorbing resin, deformation of the swelling gel surface is suppressed, and gel gaps are efficiently formed. A method is already known (see, for example, Patent Document 1). However, the surface cross-linking alone was not sufficient to make the liquid permeability between the swollen gels sufficient.
　膨潤ゲル間の通液性を向上させる手法として（１）シリカ及びタルク等の無機化合物を添加することにより物理的なスペースを形成させる方法、（２）変性シリコーン等の表面自由エネルギーの小さい疎水性高分子で表面処理することにより、膨潤ゲル同士の合着を抑制してゲル間隙を形成させる方法及び（３）硫酸アルミニウムや乳酸アルミニウム等を添加する方法が既に知られている（例えば、特許文献２、特許文献３及び特許文献４参照）。しかしながらこれらの方法では、初期膨潤時の耐ブロッキング性が不十分であるため、パルプ等の親水性繊維を減らした場合に、吸収体中で液拡散性が不足する部位が生じ、吸収性能が安定しない問題があった。このため吸水性樹脂には更なるゲル間通液性の改善が求められていた。 As a method to improve the liquid permeability between swelling gels (1) A method of forming physical space by adding an inorganic compound such as silica and talc, (2) Hydrophobicity with small surface free energy such as modified silicone There is already known a method of forming gel gaps by suppressing adhesion of swelling gels by surface treatment with a polymer, and (3) a method of adding aluminum sulfate, aluminum lactate or the like (eg, patent documents 2, Patent Document 3 and Patent Document 4). However, in these methods, since the blocking resistance at the time of initial swelling is insufficient, when hydrophilic fibers such as pulp are reduced, there occur regions where the liquid diffusivity is insufficient in the absorber, and the absorption performance is stable. There was no problem. For this reason, the water-absorbent resin has been required to further improve the gel-to-gel flowability.
国際公開第００／０５３６６４号パンフレット WO 00/053664 pamphlet 特開２０１２－１６１７８８号公報JP 2012-161788 A 特開２０１３－１３３３９９号公報JP 2013-133399 A 特開２０１４－５１２４４０号公報JP, 2014-512440, A
　本発明の目的は、初期膨潤時の耐ブロッキング性に優れ、膨潤したゲル間の通液性及び荷重下での吸水性能に優れた吸水性樹脂を提供することである。 An object of the present invention is to provide a water-absorbent resin which is excellent in blocking resistance at the time of initial swelling, and excellent in liquid permeability between swollen gels and water absorption performance under load.
　本発明は、水溶性ビニルモノマー（ａ１）及び／又は加水分解により水溶性ビニルモノマー（ａ１）となるビニルモノマー（ａ２）、並びに架橋剤（ｂ）を必須構成単位とする架橋重合体（Ａ）と、水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）とを含み、架橋重合体（Ａ）の表面アルミ二ウム被覆率が６０～１００％である吸水性樹脂組成物、及び
　前記架橋重合体（Ａ）に、水不溶性アルミナ含有微粒子（ｃ）を架橋重合体（Ａ）の重量に基づいて０．０１～１重量％含有する水性コロイド液、及び水溶性アルミニウム塩（ｄ）を架橋重合体（Ａ）の重量に基づいて０．０５～５重量％含有する水溶液、を添加した後、架橋重合体（Ａ）を表面架橋することを特徴とする、架橋重合体（Ａ）の表面アルミ二ウム被覆率が６０～１００％である吸水性樹脂組成物の製造方法である。 The present invention relates to a water-soluble vinyl monomer (a1) and / or a cross-linked polymer (A) comprising a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis and a cross-linking agent (b) A water-absorbent resin composition comprising a water-insoluble alumina-containing fine particle (c) and a water-soluble aluminum salt (d), and having a surface aluminum coverage of 60 to 100% of the crosslinked polymer (A); An aqueous colloidal solution containing 0.01 to 1% by weight of water-insoluble alumina-containing fine particles (c) based on the weight of the crosslinked polymer (A), and a water-soluble aluminum salt (d) in the crosslinked polymer (A) An aqueous solution containing 0.05 to 5% by weight based on the weight of the crosslinked polymer (A) is added, and then the crosslinked polymer (A) is surface-crosslinked. Surface aluminum coverage Is a method for producing a water-absorbent resin composition having a content of 60 to 100%.
　本発明の吸水性樹脂組成物及び本発明の製造方法により得られる吸水性樹脂組成物は、その表面の少なくとも一部が水不溶性アルミナ含有微粒子及び水溶性アルミニウム塩で被覆されていることにより、初期膨潤時の耐ブロッキング性が高く、膨潤ゲル間の通液性が非常に優れる。そのため、様々の使用状況においても安定して優れた吸収性能（例えば液拡散性、吸収速度及び吸収量等）を発揮する。 The water-absorbent resin composition of the present invention and the water-absorbent resin composition obtained by the production method of the present invention have an initial stage by covering at least a part of the surface with water-insoluble alumina-containing fine particles and a water-soluble aluminum salt. Blocking resistance at the time of swelling is high, and liquid permeability between the swollen gels is very excellent. Therefore, stable absorption performance (for example, liquid diffusivity, absorption rate, absorption amount, etc.) is exhibited stably in various usage conditions.
ゲル通液速度を測定するための濾過円筒管を模式的に表した断面図である。It is sectional drawing which represented typically the filtration cylindrical tube for measuring gel permeation speed. ゲル通液速度を測定するための加圧軸及びおもりを模式的に表した斜視図である。It is the perspective view which represented typically the pressurization axis | shaft for measuring gel permeation speed, and weight.
　本発明の吸水性樹脂組成物は、水溶性ビニルモノマー（ａ１）及び／又は加水分解により水溶性ビニルモノマー（ａ１）となるビニルモノマー（ａ２）、並びに架橋剤（ｂ）を必須構成単位とする架橋重合体（Ａ）と、水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）とを含む。 The water-absorbent resin composition of the present invention comprises a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis and a crosslinking agent (b) as essential constitutional units. It contains a crosslinked polymer (A), water-insoluble alumina-containing fine particles (c) and a water-soluble aluminum salt (d).
　本発明における水溶性ビニルモノマー（ａ１）としては特に限定はなく、公知のモノマー、例えば、特許第３６４８５５３号公報の０００７～００２３段落に開示されている少なくとも１個の水溶性置換基とエチレン性不飽和基とを有するビニルモノマー（例えばアニオン性ビニルモノマー、非イオン性ビニルモノマー及びカチオン性ビニルモノマー）、特開２００３－１６５８８３号公報の０００９～００２４段落に開示されているアニオン性ビニルモノマー、非イオン性ビニルモノマー及びカチオン性ビニルモノマー並びに特開２００５－７５９８２号公報の００４１～００５１段落に開示されているカルボキシ基、スルホ基、ホスホノ基、水酸基、カルバモイル基、アミノ基及びアンモニオ基からなる群から選ばれる少なくとも１種を有するビニルモノマーが使用できる。 There is no particular limitation on the water-soluble vinyl monomer (a1) in the present invention, and known monomers, for example, at least one water-soluble substituent disclosed in paragraphs 0007 to 0023 of Patent No. 3648553 and ethylenic non Vinyl monomers having a saturated group (for example, anionic vinyl monomers, nonionic vinyl monomers and cationic vinyl monomers), anionic vinyl monomers disclosed in paragraphs 0009 to 0024 of JP-A No. 2003-165883, nonionic Vinyl monomer and cationic vinyl monomer, and selected from the group consisting of carboxy group, sulfo group, phosphono group, hydroxyl group, carbamoyl group, amino group and ammonio group disclosed in paragraphs 0041 to 0051 of JP-A-2005-75982 At least one Vinyl monomer having can be used.
　加水分解により水溶性ビニルモノマー（ａ１）となるビニルモノマー（ａ２）［以下、加水分解性ビニルモノマー（ａ２）ともいう。］は特に限定はなく、公知｛例えば、特許第３６４８５５３号公報の００２４～００２５段落に開示されている加水分解により水溶性置換基となる加水分解性置換基を少なくとも１個有するビニルモノマー、特開２００５－７５９８２号公報の００５２～００５５段落に開示されている少なくとも１個の加水分解性置換基［１，３－オキソ－２－オキサプロピレン（－ＣＯ－Ｏ－ＣＯ－）基、アシル基及びシアノ基等］を有するビニルモノマー｝のビニルモノマー等が使用できる。なお、水溶性ビニルモノマーとは、２５℃の水１００ｇに少なくとも１００ｇ溶解するビニルモノマーを意味する。また、加水分解性ビニルモノマー（ａ２）における加水分解性とは、水及び必要により触媒（酸又は塩基等）の作用により加水分解され、水溶性になる性質を意味する。加水分解性ビニルモノマー（ａ２）の加水分解は、重合中、重合後及びこれらの両方のいずれで行っても良いが、得られる吸水性樹脂組成物の吸収性能の観点から、重合後が好ましい。 A vinyl monomer (a2) [hereinafter, also referred to as a hydrolyzable vinyl monomer (a2), which becomes a water-soluble vinyl monomer (a1) by hydrolysis]. There is no particular limitation, and publicly known {for example, a vinyl monomer having at least one hydrolysable substituent which becomes a water-soluble substituent by hydrolysis disclosed in paragraphs 0024 to 0025 of Japanese Patent No. 3648553, JP-A At least one hydrolyzable substituent [1,3-oxo-2-oxapropylene (-CO-O-CO-) group, an acyl group and a cyano group disclosed in paragraphs 0052 to 0055 of the publication No. 2005-75982. Vinyl monomers having a group etc.] can be used. The water-soluble vinyl monomer means a vinyl monomer which dissolves at least 100 g in 100 g of water at 25 ° C. Moreover, the hydrolysability in a hydrolysable vinyl monomer (a2) means the property which is hydrolyzed by the effect | action of water and the catalyst (acid or base etc. if necessary), and becomes water solubility. The hydrolysis of the hydrolyzable vinyl monomer (a2) may be performed during polymerization, after polymerization, or both of them, but after polymerization is preferable from the viewpoint of the absorption performance of the resulting water-absorbent resin composition.
　これらの内、吸収性能等の観点から好ましいのは水溶性ビニルモノマー（ａ１）、より好ましいのはアニオン性ビニルモノマー、カルボキシ（塩）基、スルホ（塩）基、アミノ基、カルバモイル基、アンモニオ基又はモノ－、ジ－若しくはトリ－アルキルアンモニオ基を有するビニルモノマー、更に好ましいのはカルボキシ（塩）基又はカルバモイル基を有するビニルモノマー、特に好ましいのは（メタ）アクリル酸（塩）及び（メタ）アクリルアミド、とりわけ好ましいのは（メタ）アクリル酸（塩）、最も好ましいのはアクリル酸（塩）である。 Among these, water-soluble vinyl monomers (a1) are preferable from the viewpoint of absorption performance and the like, and anionic vinyl monomers, carboxy (salt) groups, sulfo (salt) groups, amino groups, carbamoyl groups and ammonio groups are more preferable. Or vinyl monomers having a mono-, di- or tri-alkylammonio group, more preferably vinyl monomers having a carboxy (salt) group or carbamoyl group, particularly preferably (meth) acrylic acid (salt) and (meth) ) Acrylamide, in particular (meth) acrylic acid (salt), most preferred acrylic acid (salt).
　なお、「カルボキシ（塩）基」は「カルボキシ基」又は「カルボキシレート基」を意味し、「スルホ（塩）基」は「スルホ基」又は「スルホネート基」を意味する。また、（メタ）アクリル酸（塩）はアクリル酸、アクリル酸塩、メタクリル酸又はメタクリル酸塩を意味し、（メタ）アクリルアミドはアクリルアミド又はメタクリルアミドを意味する。また、塩としては、アルカリ金属（リチウム、ナトリウム及びカリウム等）塩、アルカリ土類金属（マグネシウム及びカルシウム等）塩及びアンモニウム（ＮＨ４）塩等が挙げられる。これらの塩の内、吸収性能等の観点から、アルカリ金属塩及びアンモニウム塩が好ましく、更に好ましいのはアルカリ金属塩、特に好ましいのはナトリウム塩である。 Here, "carboxy (salt) group" means "carboxy group" or "carboxylate group", and "sulfo (salt) group" means "sulfo group" or "sulfonate group". Also, (meth) acrylic acid (salt) means acrylic acid, acrylic acid salt, methacrylic acid or methacrylic acid salt, and (meth) acrylamide means acrylamide or methacrylamide. Moreover, as a salt, alkali metal (lithium, sodium and potassium etc.) salt, alkaline earth metal (magnesium and calcium etc.) salt, ammonium (NH 4 ) salt etc. are mentioned. Among these salts, alkali metal salts and ammonium salts are preferable from the viewpoint of absorption performance and the like, more preferable are alkali metal salts, and particularly preferable are sodium salts.
　水溶性ビニルモノマー（ａ１）又は加水分解性ビニルモノマー（ａ２）のいずれかを構成単位とする場合、それぞれ１種を単独で構成単位としてもよく、また、必要により２種以上を構成単位としても良い。また、水溶性ビニルモノマー（ａ１）及び加水分解性ビニルモノマー（ａ２）を構成単位とする場合も同様である。また、水溶性ビニルモノマー（ａ１）及び加水分解性ビニルモノマー（ａ２）を構成単位とする場合、これらの含有モル比［（ａ１）／（ａ２）］は、７５／２５～９９／１が好ましく、更に好ましくは８５／１５～９５／５、特に好ましくは９０／１０～９３／７、最も好ましくは９１／９～９２／８である。この範囲内であると、吸収性能が更に良好となる。 When either a water-soluble vinyl monomer (a1) or a hydrolyzable vinyl monomer (a2) is used as a structural unit, one type may be used alone as a structural unit, and two or more types may also be used as a structural unit as necessary. good. The same applies to the case where the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as structural units. When the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are constituent units, their content molar ratio [(a1) / (a2)] is preferably 75/25 to 99/1. And more preferably 85/15 to 95/5, particularly preferably 90/10 to 93/7, and most preferably 91/9 to 92/8. Within this range, the absorption performance is further improved.
　架橋重合体（Ａ）の構成単位として、水溶性ビニルモノマー（ａ１）及び加水分解性ビニルモノマー（ａ２）の他に、これらと共重合可能なその他のビニルモノマー（ａ３）を構成単位とすることができる。その他のビニルモノマー（ａ３）は１種を単独で用いても、２種以上を併用してもよい。 In addition to the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), as the structural unit of the crosslinked polymer (A), other vinyl monomers (a3) copolymerizable with these as the structural unit Can. The other vinyl monomers (a3) may be used alone or in combination of two or more.
　共重合可能なその他のビニルモノマー（ａ３）としては特に限定はなく、公知（例えば、特許第３６４８５５３号公報の００２８～００２９段落に開示されている疎水性ビニルモノマー、特開２００３－１６５８８３号公報の００２５段落及び特開２００５－７５９８２号公報の００５８段落に開示されているビニルモノマー等）の疎水性ビニルモノマー等が使用でき、具体的には例えば下記の（ｉ）～（ｉｉｉ）のビニルモノマー等が使用できる。
（ｉ）炭素数８～３０の芳香族エチレン性モノマー
　スチレン、α－メチルスチレン、ビニルトルエン及びヒドロキシスチレン等のスチレン、並びにビニルナフタレン、並びにジクロルスチレン等のスチレンのハロゲン置換体等。
（ｉｉ）炭素数２～２０の脂肪族エチレン性モノマー
　アルケン（エチレン、プロピレン、ブテン、イソブチレン、ペンテン、ヘプテン、ジイソブチレン、オクテン、ドデセン及びオクタデセン等）；並びにアルカジエン（ブタジエン及びイソプレン等）等。
（ｉｉｉ）炭素数５～１５の脂環式エチレン性モノマー
　モノエチレン性不飽和モノマー（ピネン、リモネン及びインデン等）；並びにポリエチレン性ビニルモノマー［シクロペンタジエン、ビシクロペンタジエン及びエチリデンノルボルネン等］等。 There is no particular limitation on the copolymerizable other vinyl monomer (a3), and known vinyl monomers (for example, hydrophobic vinyl monomers disclosed in Japanese Patent No. 3648553, paragraphs 0028 to 0029, JP-A No. 2003-165883 Hydrophobic vinyl monomers etc. such as vinyl monomers disclosed in paragraph 0025 and paragraph 0058 of JP-A-2005-75982 can be used. Specifically, for example, vinyl monomers of the following (i) to (iii) Can be used.
(I) Aromatic ethylenic monomers having 8 to 30 carbon atoms Styrene, styrene such as α-methylstyrene, vinyl toluene and hydroxystyrene, vinyl naphthalene, halogen-substituted styrene such as dichlorostyrene, and the like.
(Ii) Aliphatic ethylenic monomers having 2 to 20 carbon atoms: Alkenes (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.); and alkadienes (butadiene, isoprene etc.), etc.
(Iii) Alicyclic ethylenic monomers having 5 to 15 carbon atoms Monoethylenically unsaturated monomers (pinene, limonene, indene etc.); and polyethylene vinyl monomers [cyclopentadiene, bicyclopentadiene, ethylidene norbornene etc.] etc.
　その他のビニルモノマー（ａ３）単位の含有量（モル％）は、吸収性能等の観点から、水溶性ビニルモノマー（ａ１）単位及び加水分解性ビニルモノマー（ａ２）単位の合計モル数に基づいて、０～５が好ましく、更に好ましくは０～３、特に好ましくは０～２、とりわけ好ましくは０～１．５であり、吸収性能等の観点から、その他のビニルモノマー（ａ３）単位の含有量が０モル％であることが最も好ましい。 The content (mol%) of the other vinyl monomer (a3) units is based on the total number of moles of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit from the viewpoint of absorption performance etc. It is preferably 0 to 5, more preferably 0 to 3, particularly preferably 0 to 2, particularly preferably 0 to 1.5, and the content of the other vinyl monomer (a3) unit is preferably from the viewpoint of absorption performance and the like. Most preferably, it is 0 mol%.
　架橋剤（ｂ）としては特に限定はなく公知（例えば、特許第３６４８５５３号公報の００３１～００３４段落に開示されているエチレン性不飽和基を２個以上有する架橋剤、水溶性置換基と反応し得る官能基を少なくとも１個有してかつ少なくとも１個のエチレン性不飽和基を有する架橋剤及び水溶性置換基と反応し得る官能基を少なくとも２個有する架橋剤、特開２００３－１６５８８３号公報の００２８～００３１段落に開示されているエチレン性不飽和基を２個以上有する架橋剤、エチレン性不飽和基と反応性官能基とを有する架橋剤及び反応性置換基を２個以上有する架橋剤、特開２００５－７５９８２号公報の００５９段落に開示されている架橋性ビニルモノマー並びに特開２００５－９５７５９号公報の００１５～００１６段落に開示されている架橋性ビニルモノマー）の架橋剤等が使用できる。これらの内、吸収性能等の観点から、エチレン性不飽和基を２個以上有する架橋剤が好ましく、更に好ましいのは、炭素数２～４０の多価アルコールのポリ（メタ）アリルエーテル、炭素数２～４０の多価アルコールの（メタ）アクリレート、炭素数２～４０の多価アルコールの（メタ）アクリルアミド、特に好ましいのは炭素数２～４０の多価アルコールのポリアリルエーテル、最も好ましいのはペンタエリスリトールトリアリルエーテルである。架橋剤（ｂ）は１種を単独で用いても、２種以上を併用してもよい。 The crosslinking agent (b) is not particularly limited and is known (for example, it reacts with a crosslinking agent having two or more ethylenic unsaturated groups disclosed in paragraphs 0031 to 0034 of Japanese Patent No. 3648553, a water-soluble substituent). JP-A 2003-165883 having at least one functional group and at least one crosslinking agent having at least one ethylenically unsaturated group, and at least two functional groups capable of reacting with a water-soluble substituent, The crosslinking agent having two or more ethylenic unsaturated groups, the crosslinking agent having an ethylenic unsaturated group and a reactive functional group, and the crosslinking agent having two or more reactive substituents, disclosed in paragraphs 0028 to 0031 of And crosslinkable vinyl monomers disclosed in paragraph [0059] of JP-A-2005-75982 and steps 0015 to 0016 of JP-A-2005-95759. Crosslinking agents such as disclosed crosslinkable vinyl monomer) can be used to. Among them, in view of absorption performance etc., a crosslinking agent having two or more ethylenically unsaturated groups is preferable, and poly (meth) allyl ether of polyhydric alcohol having 2 to 40 carbon atoms, more preferably carbon number is more preferable. (Meth) acrylate of polyhydric alcohol of 2 to 40, (meth) acrylamide of polyhydric alcohol of 2 to 40 carbon atoms, particularly preferably polyallyl ether of polyhydric alcohol of 2 to 40 carbon atoms, most preferably Pentaerythritol triallyl ether. The crosslinking agent (b) may be used alone or in combination of two or more.
　架橋剤（ｂ）単位の含有量（モル％）は、水溶性ビニルモノマー（ａ１）単位及び加水分解性ビニルモノマー（ａ２）単位の、その他のビニルモノマー（ａ３）を用いる場合は（ａ１）～（ａ３）の、合計モル数に基づいて、０．００１～５が好ましく、更に好ましくは０．００５～３、特に好ましくは０．０１～１である。この範囲であると、吸収性能が更に良好となる。 The content (mol%) of the crosslinker (b) unit is (a1) to (a1) when the other vinyl monomer (a3) of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit is used It is preferably 0.001 to 5, more preferably 0.005 to 3, particularly preferably 0.01 to 1, based on the total number of moles of (a3). Within this range, the absorption performance is further improved.
　架橋重合体（Ａ）の製造方法としては、公知の溶液重合（断熱重合、薄膜重合及び噴霧重合法等；特開昭５５－１３３４１３号公報等）や、公知の懸濁重合法や逆相懸濁重合（特公昭５４－３０７１０号公報、特開昭５６－２６９０９号公報及び特開平１－５８０８号公報等）によって得られる含水ゲル重合体（架橋重合体と水とからなる。）を必要により加熱乾燥、粉砕することで得ることができる。架橋重合体（Ａ）は、１種単独でも良いし、２種以上の混合物であっても良い。 As a method of producing the crosslinked polymer (A), known solution polymerization (diathermal polymerization, thin film polymerization, spray polymerization method, etc .; JP-A-55-133413, etc.), known suspension polymerization method, reverse phase polymerization, etc. A water-containing gel polymer (consisting of a cross-linked polymer and water) obtained by turbid polymerization (JP-B 54-30710, JP-A 56-26909, JP-A 1-5 808, etc.) may be used if necessary. It can be obtained by heat drying and crushing. The crosslinked polymer (A) may be used alone or in combination of two or more.
　重合方法の内、好ましいのは溶液重合法であり、有機溶媒等を使用する必要がなく生産コスト面で有利なことから、特に好ましいのは水溶液重合法であり、保水量が大きく、且つ水可溶性成分量の少ない吸水性樹脂が得られ、重合時の温度コントロールが不要である点から、水溶液断熱重合法が最も好ましい。 Among the polymerization methods, the solution polymerization method is preferable, and the aqueous solution polymerization method is particularly preferable since it is not necessary to use an organic solvent etc. and advantageous in terms of production cost, and the water retention amount is large and water soluble. The aqueous solution adiabatic polymerization method is most preferable because a water-absorbent resin with a small amount of components is obtained, and temperature control at the time of polymerization is unnecessary.
　水溶液重合を行う場合、水と有機溶媒とを含む混合溶媒を使用することができ、有機溶媒としては、メタノール、エタノール、アセトン、メチルエチルケトン、Ｎ，Ｎ－ジメチルホルムアミド、ジメチルスルホキシド及びこれらの２種以上の混合物を挙げられる。
　水溶液重合を行う場合、有機溶媒の使用量（重量％）は、水の重量を基準として４０以下が好ましく、更に好ましくは３０以下である。 When aqueous solution polymerization is performed, a mixed solvent containing water and an organic solvent can be used, and as the organic solvent, methanol, ethanol, acetone, methyl ethyl ketone, N, N-dimethylformamide, dimethyl sulfoxide and two or more of them can be used. A mixture of
When aqueous solution polymerization is performed, the amount (% by weight) of the organic solvent used is preferably 40 or less, more preferably 30 or less based on the weight of water.
　重合に触媒を用いる場合、従来公知のラジカル重合用触媒が使用可能であり、例えば、アゾ化合物［アゾビスイソブチロニトリル、アゾビスシアノ吉草酸及び２，２’－アゾビス（２－アミジノプロパン）ハイドロクロライド等］、無機過酸化物（過酸化水素、過硫酸アンモニウム、過硫酸カリウム及び過硫酸ナトリウム等）、有機過酸化物［過酸化ベンゾイル、ジ－ｔ－ブチルパーオキサイド、クメンヒドロパーオキサイド、コハク酸パーオキサイド及びジ（２－エトキシエチル）パーオキシジカーボネート等］及びレドックス触媒（アルカリ金属の亜硫酸塩又は重亜硫酸塩、亜硫酸アンモニウム、重亜硫酸アンモニウム及びアスコルビン酸等の還元剤とアルカリ金属の過硫酸塩、過硫酸アンモニウム、過酸化水素及び有機過酸化物等の酸化剤との組み合わせよりなるもの）等が挙げられる。これらの触媒は、単独で使用してもよく、これらの２種以上を併用しても良い。
　ラジカル重合触媒の使用量（重量％）は、水溶性ビニルモノマー（ａ１）及び加水分解性ビニルモノマー（ａ２）の、その他のビニルモノマー（ａ３）を用いる場合は（ａ１）～（ａ３）の、合計重量に基づいて、０．０００５～５が好ましく、更に好ましくは０．００１～２である。 When a catalyst is used for the polymerization, conventionally known catalysts for radical polymerization can be used. For example, azo compounds [azobisisobutyronitrile, azobiscyanovaleric acid and 2,2'-azobis (2-amidinopropane) hydrochloride are used. Etc.], inorganic peroxides (eg hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate), organic peroxides [benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, succinic acid peroxide Oxides and di (2-ethoxyethyl) peroxydicarbonate etc] and redox catalysts (sulfites or bisulfites of alkali metals, ammonium sulfite, ammonium bisulfite and ascorbic acid etc, reducing agents and persulfates of alkali metals, Oxidation of ammonium persulfate, hydrogen peroxide and organic peroxides And the like, and the like. These catalysts may be used alone, or two or more of these may be used in combination.
The amount (% by weight) of the radical polymerization catalyst used is the water soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), and the other vinyl monomers (a3) of (a1) to (a3) Based on the total weight, 0.0005 to 5 is preferable, and more preferably 0.001 to 2.
　重合時には、必要に応じて連鎖移動剤等の重合コントロール剤を併用しても良く、これらの具体例としては、次亜リン酸ナトリウム、亜リン酸ナトリウム、アルキルメルカプタン、ハロゲン化アルキル、チオカルボニル化合物等が挙げられる。これらの重合コントロール剤は、単独で使用してもよく、これらの２種以上を併用しても良い。
　重合コントロール剤の使用量（重量％）は、水溶性ビニルモノマー（ａ１）及び加水分解性ビニルモノマー（ａ２）の、その他のビニルモノマー（ａ３）を用いる場合は（ａ１）～（ａ３）の、合計重量に基づいて、０．０００５～５が好ましく、更に好ましくは０．００１～２である。 At the time of polymerization, if necessary, a polymerization control agent such as a chain transfer agent may be used in combination, and specific examples thereof include sodium hypophosphite, sodium phosphite, alkyl mercaptan, alkyl halide, thiocarbonyl compound Etc. These polymerization control agents may be used alone, or two or more of these may be used in combination.
The use amount (% by weight) of the polymerization control agent is the water soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), and the other vinyl monomers (a3) of (a1) to (a3) Based on the total weight, 0.0005 to 5 is preferable, and more preferably 0.001 to 2.
　重合方法として懸濁重合法又は逆相懸濁重合法をとる場合は、必要に応じて、従来公知の分散剤又は界面活性剤の存在下に重合を行っても良い。また、逆相懸濁重合法の場合、従来公知のキシレン、ノルマルヘキサン及びノルマルヘプタン等の炭化水素系溶媒を使用して重合を行うことができる。 When the suspension polymerization method or the reverse phase suspension polymerization method is employed as the polymerization method, the polymerization may be carried out in the presence of a conventionally known dispersant or surfactant, if necessary. In the case of reverse phase suspension polymerization, polymerization can be carried out using a hydrocarbon solvent such as xylene, normal hexane and normal heptane which are conventionally known.
　重合開始温度は、使用する触媒の種類によって適宜調整することができるが、０～１００℃が好ましく、更に好ましくは２～８０℃である。 The polymerization initiation temperature can be appropriately adjusted depending on the type of catalyst used, but it is preferably 0 to 100 ° C., more preferably 2 to 80 ° C.
　重合に溶媒（有機溶媒及び水等）を使用する場合、重合後に溶媒を留去することが好ましい。溶媒に有機溶媒を含む場合、留去後の有機溶媒の含有量（重量％）は、架橋重合体（Ａ）の重量に基づいて、０～１０が好ましく、更に好ましくは０～５、特に好ましくは０～３、最も好ましくは０～１である。この範囲であると、吸水性樹脂組成物の吸収性能が更に良好となる。 When a solvent (such as an organic solvent and water) is used for the polymerization, the solvent is preferably distilled off after the polymerization. When the solvent contains an organic solvent, the content (% by weight) of the organic solvent after distillation is preferably 0 to 10, more preferably 0 to 5, particularly preferably, based on the weight of the crosslinked polymer (A). Is 0-3, most preferably 0-1. Within this range, the absorption performance of the water-absorbent resin composition is further improved.
　溶媒に水を含む場合、留去後の水分（重量％）は、架橋重合体（Ａ）の重量に基づいて、０～２０が好ましく、更に好ましくは１～１０、特に好ましくは２～９、最も好ましくは３～８である。この範囲であると、吸収性能が更に良好となる。 When the solvent contains water, the water content after distillation (% by weight) is preferably 0 to 20, more preferably 1 to 10, particularly preferably 2 to 9, based on the weight of the crosslinked polymer (A). Most preferably, it is 3-8. Within this range, the absorption performance is further improved.
　前記の重合方法により架橋重合体（Ａ）が水を含んだ含水ゲル状物（以下、含水ゲルと略記する）を得ることができ、更に含水ゲルを乾燥することで架橋重合体（Ａ）を得ることができる。
　水溶性ビニルモノマー（ａ１）としてアクリル酸やメタクリル酸等の酸基含有モノマーを用いる場合、含水ゲルを塩基で中和しても良い。酸基の中和度は、５０～８０モル％であることが好ましい。中和度が５０モル％未満の場合、得られる含水ゲル重合体の粘着性が高くなり、製造時及び使用時の作業性が悪化する場合がある。更に得られる吸水性樹脂組成物の保水量が低下する場合がある。一方、中和度が８０％を超える場合、得られた樹脂のｐＨが高くなり人体の皮膚に対する安全性が懸念される場合がある。
　なお、中和は、吸水性樹脂組成物の製造において、架橋重合体（Ａ）の重合以降のいずれの段階で行ってもよく、例えば、含水ゲルの状態で中和する等の方法が好ましい例として例示される。
　中和する塩基としては、水酸化ナトリウム、水酸化カリウム等のアルカリ金属水酸化物や、炭酸ナトリウム、炭酸水素ナトリウム、炭酸カリウム等のアルカリ金属炭酸塩を通常使用できる。 The water-containing gel-like product (hereinafter abbreviated as water-containing gel) in which the crosslinked polymer (A) contains water can be obtained by the polymerization method described above, and the crosslinked polymer (A) can be obtained by further drying the water-containing gel. You can get it.
When an acid group-containing monomer such as acrylic acid or methacrylic acid is used as the water-soluble vinyl monomer (a1), the water-containing gel may be neutralized with a base. The neutralization degree of the acid group is preferably 50 to 80 mol%. When the degree of neutralization is less than 50 mol%, the tackiness of the resulting water-containing gel polymer may be high, and the workability at the time of production and use may be deteriorated. Furthermore, the water retention amount of the water-absorbent resin composition obtained may be reduced. On the other hand, when the degree of neutralization exceeds 80%, the pH of the obtained resin may be high, which may cause the safety of the skin of the human body.
The neutralization may be carried out at any stage after the polymerization of the crosslinked polymer (A) in the production of the water-absorbent resin composition, and for example, a method such as a method of neutralizing in the state of a water-containing gel is preferred. It is illustrated as
As a base to be neutralized, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates such as sodium carbonate, sodium hydrogencarbonate and potassium carbonate can usually be used.
　重合によって得られる含水ゲルは、必要に応じて細断することができる。細断後のゲルの大きさ（最長径）は５０μｍ～１０ｃｍが好ましく、更に好ましくは１００μｍ～２ｃｍ、特に好ましくは１ｍｍ～１ｃｍである。この範囲であると、乾燥工程での乾燥性が更に良好となる。 The water-containing gel obtained by polymerization can be shredded if necessary. The size (longest diameter) of the shredded gel is preferably 50 μm to 10 cm, more preferably 100 μm to 2 cm, and particularly preferably 1 mm to 1 cm. Within this range, the drying property in the drying step is further improved.
　細断は、公知の方法で行うことができ、細断装置（例えば、ベックスミル、ラバーチョッパ、ファーマミル、ミンチ機、衝撃式粉砕機及びロール式粉砕機）等を使用して細断できる。 The shredding can be performed by a known method, and shredding can be performed using a shredding apparatus (for example, a beck mill, a rubber chopper, a farm mill, a mincing machine, an impact crusher and a roll crusher) or the like.
　なお、有機溶媒の含有量及び水分は、赤外水分測定器［例えば、（株）ＫＥＴＴ社製ＪＥ４００等：１２０±５℃、３０分、加熱前の雰囲気湿度５０±１０％ＲＨ、ランプ仕様１００Ｖ、４０Ｗ］により加熱したときの測定試料の重量減量から求められる。 In addition, the content of organic solvent and the moisture, infrared moisture measuring instrument [for example, JET400 manufactured by KETT Co., Ltd .: 120 ± 5 ° C, 30 minutes, atmospheric humidity before heating 50 ± 10% RH, lamp specification 100 V , 40 W] is obtained from the weight loss of the measurement sample when heated.
　含水ゲル中の溶媒（水を含む）を留去する方法としては、８０～２３０℃の温度の熱風で留去（乾燥）する方法、１００～２３０℃に加熱されたドラムドライヤー等による薄膜乾燥法、（加熱）減圧乾燥法、凍結乾燥法、赤外線による乾燥法、デカンテーション及び濾過等が適用できる。 As a method of distilling off the solvent (including water) in the water-containing gel, a method of distilling (drying) with hot air at a temperature of 80 to 230 ° C., a thin film drying method by a drum dryer heated to 100 to 230 ° C. (Heating) reduced-pressure drying method, lyophilization method, infrared ray drying method, decantation and filtration can be applied.
　含水ゲルを乾燥して架橋重合体（Ａ）を得た後、更に粉砕することができる。粉砕方法については、特に限定はなく、粉砕装置（例えば、ハンマー式粉砕機、衝撃式粉砕機、ロール式粉砕機及びシェット気流式粉砕機）等が使用できる。粉砕された架橋重合体は、必要によりふるい分け等により粒度調整できる。 After drying the water-containing gel to obtain a crosslinked polymer (A), it can be further pulverized. There is no particular limitation on the grinding method, and a grinding device (for example, a hammer type crusher, an impact type crusher, a roll crusher, a shet type crusher, etc.) can be used. The particle size of the pulverized crosslinked polymer can be adjusted by sieving, if necessary.
　必要によりふるい分けされた架橋重合体（Ａ）の重量平均粒子径（μｍ）は、１００～８００が好ましく、更に好ましくは２００～７００、次に好ましくは２５０～６００、特に好ましくは３００～５００、最も好ましくは３５０～４５０である。この範囲であると、吸収性能が更に良好となる。 The weight-average particle size (μm) of the cross-linked polymer (A) optionally sieved is preferably 100 to 800, more preferably 200 to 700, next preferably 250 to 600, particularly preferably 300 to 500, most preferably Preferably it is 350-450. Within this range, the absorption performance is further improved.
　なお、重量平均粒子径は、ロータップ試験篩振とう機及び標準ふるい（ＪＩＳ　Ｚ８８０１－１：２００６）を用いて、ペリーズ・ケミカル・エンジニアーズ・ハンドブック第６版（マックグローヒル・ブック・カンバニー、１９８４、２１頁）に記載の方法で測定される。すなわち、ＪＩＳ標準ふるいを、上から１０００μｍ、８５０μｍ、７１０μｍ、５００μｍ、４２５μｍ、３５５μｍ、２５０μｍ、１５０μｍ、１２５μｍ、７５μｍ及び４５μｍ、並びに受け皿、の順に組み合わせる。最上段のふるいに測定粒子の約５０ｇを入れ、ロータップ試験篩振とう機で５分間振とうさせる。各ふるい及び受け皿上の測定粒子の重量を秤量し、その合計を１００重量％として各ふるい上の粒子の重量分率を求め、この値を対数確率紙［横軸がふるいの目開き（粒子径）、縦軸が重量分率］にプロットした後、各点を結ぶ線を引き、重量分率が５０重量％に対応する粒子径を求め、これを重量平均粒子径とする。 The weight-average particle size is determined using the low tap test sieve shaker and standard sieves (JIS Z8801-1: 2006) according to Perry's Chemical Engineers Handbook 6th Edition (McGrow Hill Book, Inc. 1984) , Page 21). That is, JIS standard sieves are combined in the order of 1000 μm, 850 μm, 710 μm, 500 μm, 425 μm, 355 μm, 250 μm, 150 μm, 125 μm, 75 μm and 45 μm from the top, and a pan. About 50 g of the measurement particles are placed in the uppermost sieve and shaken for 5 minutes with a low tap test sieve shaker. The weight of the measurement particles on each sieve and receiver is weighed, and the weight fraction of the particles on each sieve is determined by taking the total as 100% by weight. After plotting the weight fraction on the vertical axis), a line connecting points is drawn to obtain a particle size corresponding to 50% by weight of the weight fraction, which is defined as a weight average particle size.
　また、架橋重合体（Ａ）に含まれる微粒子の含有量は少ない方が吸収性能が良好となるため、架橋重合体（Ａ）の合計重量に占める１０６μｍ以下（好ましくは１５０μｍ以下）の微粒子の含有率（重量％）は３以下が好ましく、更に好ましくは１以下である。微粒子の含有量は、上記の重量平均粒子径を求める際に作成するグラフを用いて求めることができる。 In addition, the smaller the content of the fine particles contained in the crosslinked polymer (A), the better the absorption performance, so the inclusion of fine particles of 106 μm or less (preferably 150 μm or less) in the total weight of the crosslinked polymer (A) The ratio (% by weight) is preferably 3 or less, more preferably 1 or less. The content of the fine particles can be determined using a graph created when determining the above-described weight average particle diameter.
　架橋重合体（Ａ）の形状については特に限定はなく、不定形破砕状、リン片状、パール状及び米粒状等が挙げられる。これらのうち、紙おむつ用途等での繊維状物とのからみが良く、繊維状物からの脱落の心配がないという観点から、不定形破砕状が好ましい。 The shape of the crosslinked polymer (A) is not particularly limited, and examples thereof include irregularly crushed, scaly, pearly and rice grains. Among these, from the viewpoint of good interlocking with the fibrous material in paper diaper applications and the like and no concern of detachment from the fibrous material, the irregularly crushed material is preferable.
　なお、架橋重合体（Ａ）は、その性能を損なわない範囲で残留溶媒や残存架橋成分等の他の成分を多少含んでも良い。 The crosslinked polymer (A) may contain some other components such as a residual solvent and a residual crosslinking component as long as the performance is not impaired.
　本発明の吸水性樹脂組成物は、架橋重合体（Ａ）の表面が有機表面架橋剤（ｅ）により架橋された構造を有することが好ましい。架橋重合体（Ａ）の表面を架橋することにより吸水性樹脂組成物のゲル強度を向上させることができ、吸水性樹脂組成物の望ましい保水量と荷重下における吸収量とをより一層満足させることができる。有機表面架橋剤（ｅ）としては、公知（特開昭５９－１８９１０３号公報に記載の多価グリシジル化合物、多価アミン、多価アジリジン化合物及び多価イソシアネート化合物等、特開昭５８－１８０２３３号公報及び特開昭６１－１６９０３号公報の多価アルコール、特開昭６１－２１１３０５号公報及び特開昭６１－２５２２１２号公報に記載のシランカップリング剤、特表平５－５０８４２５号公報に記載のアルキレンカーボネート、特開平１１－２４０９５９号公報に記載の多価オキサゾリン化合物等）の有機表面架橋剤等が使用できる。これらの表面架橋剤のうち、経済性及び吸収特性の観点から、多価グリシジル化合物、多価アルコール及び多価アミンが好ましく、更に好ましいのは多価グリシジル化合物及び多価アルコール、特に好ましいのは多価グリシジル化合物、最も好ましいのはエチレングリコールジグリシジルエーテルである。有機表面架橋剤（ｅ）は１種を単独で用いても良いし、２種以上を併用しても良い。 The water-absorbent resin composition of the present invention preferably has a structure in which the surface of the crosslinked polymer (A) is crosslinked by the organic surface crosslinking agent (e). By crosslinking the surface of the crosslinked polymer (A), the gel strength of the water absorbent resin composition can be improved, and the desired water retention amount of the water absorbent resin composition and the absorption amount under load can be further satisfied. Can. Examples of the organic surface crosslinking agent (e) include known polyvalent glycidyl compounds, polyvalent amines, polyvalent aziridine compounds and polyvalent isocyanate compounds described in JP-A-59-189103, JP-A-58-180233, etc. And polyhydric alcohols described in JP-A-61-16903, silane coupling agents described in JP-A-61-211305 and JP-A-61-252212, described in JP-A-5-508425. And the organic surface cross-linking agents of polyvalent oxazoline compounds described in JP-A No. 11-240959, etc. can be used. Among these surface crosslinking agents, polyvalent glycidyl compounds, polyhydric alcohols and polyhydric amines are preferable from the viewpoint of economy and absorption characteristics, and polyvalent glycidyl compounds and polyhydric alcohols are more preferable, and polyvalent glycidyl compounds are more preferable. Glycidyl compounds, most preferably ethylene glycol diglycidyl ether. The organic surface crosslinking agent (e) may be used alone or in combination of two or more.
　表面架橋をする場合、有機表面架橋剤（ｅ）の使用量（重量％）は、表面架橋剤の種類、架橋させる条件、目標とする性能等により種々変化させることができるため特に限定はないが、吸収特性の観点等から、吸水性樹脂組成物の重量に基づいて、０．００１～３が好ましく、更に好ましくは０．００５～２、特に好ましくは０．０１～１．５である。 When surface crosslinking is performed, the amount (% by weight) of the organic surface crosslinking agent (e) used is not particularly limited because it can be variously changed depending on the type of the surface crosslinking agent, the conditions for crosslinking, and the target performance. From the viewpoint of absorption characteristics, etc., 0.001 to 3 is preferable based on the weight of the water absorbent resin composition, more preferably 0.005 to 2, and particularly preferably 0.01 to 1.5.
　架橋重合体（Ａ）の表面架橋は、架橋重合体（Ａ）と有機表面架橋剤（ｅ）とを混合し、加熱することで行うことができる。架橋重合体（Ａ）と有機表面架橋剤（ｅ）との混合方法としては、円筒型混合機、スクリュー型混合機、スクリュー型押出機、タービュライザー、ナウター型混合機、双腕型ニーダー、流動式混合機、Ｖ型混合機、ミンチ混合機、リボン型混合機、気流型混合機、回転円盤型混合機、コニカルブレンダー及びロールミキサー等の混合装置を用いて架橋重合体（Ａ）と有機表面架橋剤（ｅ）とを均一混合する方法が挙げられる。この際、有機表面架橋剤（ｅ）は、水及び／又は任意の溶剤で希釈して使用しても良い。 The surface crosslinking of the crosslinked polymer (A) can be carried out by mixing the crosslinked polymer (A) and the organic surface crosslinking agent (e) and heating. As a mixing method of the crosslinked polymer (A) and the organic surface crosslinking agent (e), a cylindrical mixer, screw mixer, screw extruder, turbulizer, Nauta mixer, double-arm kneader, Cross-linked polymer (A) and organic using mixing equipment such as flow type mixer, V type mixer, minced mixer, ribbon type mixer, air flow type mixer, rotary disk type mixer, conical blender and roll mixer The method of mixing uniformly with the surface crosslinking agent (e) is mentioned. At this time, the organic surface crosslinking agent (e) may be used after being diluted with water and / or any solvent.
　架橋重合体（Ａ）と有機表面架橋剤（ｅ）とを混合する際の温度は特に限定されないが、１０～１５０℃が好ましく、更に好ましくは２０～１００℃、特に好ましくは２５～８０℃である。 Although the temperature at the time of mixing the crosslinked polymer (A) and the organic surface crosslinking agent (e) is not particularly limited, it is preferably 10 to 150 ° C., more preferably 20 to 100 ° C., particularly preferably 25 to 80 ° C. is there.
　架橋重合体（Ａ）と有機表面架橋剤（ｅ）とを混合した後、通常、加熱処理を行う。加熱温度は、樹脂粒子の耐壊れ性の観点から好ましくは１００～１８０℃、更に好ましくは１１０～１７５℃、特に好ましくは１２０～１７０℃である。１８０℃以下の加熱であれば蒸気を利用した間接加熱が可能であり設備上有利であり、１００℃未満の加熱温度では吸収性能が悪くなる場合がある。また、加熱時間は加熱温度により適宜設定することができるが、吸収性能の観点から、好ましくは５～６０分、更に好ましくは１０～４０分である。表面架橋して得られる吸水性樹脂を、最初に用いた有機表面架橋剤と同種又は異種の有機表面架橋剤を用いて、更に表面架橋することも可能である。 After mixing the crosslinked polymer (A) and the organic surface crosslinking agent (e), heat treatment is usually performed. The heating temperature is preferably 100 to 180 ° C., more preferably 110 to 175 ° C., particularly preferably 120 to 170 ° C. from the viewpoint of the breakage resistance of the resin particles. In the case of heating at 180 ° C. or lower, indirect heating using steam is possible, which is advantageous in equipment, and the absorption performance may be deteriorated at a heating temperature of less than 100 ° C. The heating time can be appropriately set according to the heating temperature, but is preferably 5 to 60 minutes, more preferably 10 to 40 minutes, from the viewpoint of absorption performance. It is also possible to further crosslink the surface of the water-absorbent resin obtained by surface cross-linking, using an organic surface cross-linking agent of the same or different type as the organic surface cross-linking agent used first.
　架橋重合体（Ａ）の表面を有機表面架橋剤（ｅ）により架橋した後、必要により篩別して粒度調整される。得られた粒子の平均粒経は、好ましくは１００～６００μｍ、更に好ましくは２００～５００μｍである。微粒子の含有量は少ない方が好ましく、１００μｍ以下の粒子の含有量は３重量％以下であることが好ましく、１５０μｍ以下の粒子の含有量が３重量％以下であることが更に好ましい。 After crosslinking the surface of the crosslinked polymer (A) with the organic surface crosslinking agent (e), the particle size is adjusted by sieving as required. The average particle size of the obtained particles is preferably 100 to 600 μm, more preferably 200 to 500 μm. The content of the fine particles is preferably small, the content of particles of 100 μm or less is preferably 3% by weight or less, and the content of particles of 150 μm or less is more preferably 3% by weight or less.
　本発明の吸水性樹脂組成物は、水不溶性アルミナ含有微粒子（ｃ）を含む。水不溶性アルミナ含有微粒子（ｃ）としては、アルミナ（酸化アルミニウム）微粒子、アルミナ変性シリカ微粒子、ベーマイト微粒子、水酸化アルミニウム微粒子、リン酸アルミニウム微粒子、ゼオライトやモンモリロナイト等のアルミノケイ酸塩微粒子等が挙げられ、入手の容易性や扱いやすさ、吸収性能の観点から、アルミナ微粒子及びアルミナ変性シリカ微粒子が好ましく、更に好ましいのはアルミナ変性シリカ微粒子である。（ｃ）は１種を単独で用いても良いし、２種以上を併用しても良い。ここで、アルミナ変性シリカとは、一般にシリカ微粒子の表面の少なくとも一部がアルミナで被覆された構造を有する微粒子を指す。 The water-absorbent resin composition of the present invention contains water-insoluble alumina-containing fine particles (c). Examples of the water-insoluble alumina-containing particles (c) include alumina (aluminum oxide) particles, alumina-modified silica particles, boehmite particles, aluminum hydroxide particles, aluminum phosphate particles, and aluminosilicate particles such as zeolite and montmorillonite. Alumina fine particles and alumina-modified silica fine particles are preferable, and alumina-modified silica fine particles are more preferable, from the viewpoints of easy availability, easy handling, and absorption performance. As (c), one type may be used alone, or two or more types may be used in combination. Here, alumina-modified silica generally refers to fine particles having a structure in which at least a portion of the surface of the fine silica particles is coated with alumina.
　本発明における水不溶性アルミナ含有微粒子（ｃ）は、平均一次粒子径１～１００ｎｍの球状又は不定形の粒子であることが好ましい。球状又は不定形の粒子であると、吸水性樹脂組成物の粉体流動性が良好となる。水不溶性アルミナ含有微粒子（ｃ）の平均一次粒子径は、好ましくは２～８０ｎｍであり、更に好ましくは３～６０ｎｍ、特に好ましくは５～５０ｎｍ、最も好ましくは５～２０ｎｍである。平均一次粒子径が１ｎｍより小さいと吸水性樹脂組成物の荷重下での吸収特性が悪化する場合がある。また１００ｎｍより大きいと吸水性樹脂組成物の通液性が悪化する場合がある。
　なお、水不溶性アルミナ含有微粒子（ｃ）の平均一次粒子径の測定は従来公知の方法で行えばよく、例えば、透過型電子顕微鏡での５万倍の画像から１００個以上の粒子について個々の粒子の最長径と最短経との平均から粒子径を実測してその平均値を求める方法や、動的光散乱やレーザー回折法を用いた散乱式粒度分布測定装置を用いる方法、球状粒子である場合ＢＥＴ法による比表面積から算出する方法等が挙げられる。市販品を使用する場合には、そのカタログ値で代用できる。なお、測定により求める場合に測定方法により有意な相違がある場合は、上述の透過型電子顕微鏡を用いる方法による。この方法では粒子数をカウントして、個数基準平均粒子径が得られる。 The water-insoluble alumina-containing fine particles (c) in the present invention are preferably spherical or amorphous particles having an average primary particle size of 1 to 100 nm. When the particles are spherical or amorphous, the powder flowability of the water-absorbent resin composition becomes good. The average primary particle diameter of the water-insoluble alumina-containing fine particles (c) is preferably 2 to 80 nm, more preferably 3 to 60 nm, particularly preferably 5 to 50 nm, and most preferably 5 to 20 nm. If the average primary particle size is smaller than 1 nm, the absorption characteristics of the water-absorbent resin composition under load may be deteriorated. When the particle diameter is larger than 100 nm, the liquid permeability of the water-absorbent resin composition may be deteriorated.
The measurement of the average primary particle size of the water-insoluble alumina-containing fine particles (c) may be performed by a conventionally known method, for example, individual particles of 100 or more particles from an image of 50,000 times with a transmission electron microscope Method of measuring the particle diameter from the average of the longest diameter and the shortest diameter of the particle to obtain the average value, a method using a scattering type particle size distribution measuring apparatus using dynamic light scattering or laser diffraction method, or spherical particles The method etc. which are calculated from the specific surface area by BET method are mentioned. When using a commercial item, its catalog value can be substituted. In addition, when there exists significant difference by a measurement method, when calculating | requiring by measurement, it is by the method of using the above-mentioned transmission electron microscope. In this method, the number of particles is counted to obtain a number-based average particle diameter.
　本発明の吸水性樹脂組成物は、架橋重合体（Ａ）と水不溶性アルミナ含有微粒子（ｃ）とを混合することで得ることができる。混合方法としては、円筒型混合機、スクリュー型混合機、スクリュー型押出機、タービュライザー、ナウター型混合機、双腕型ニーダー、流動式混合機、Ｖ型混合機、ミンチ混合機、リボン型混合機、気流型混合機、回転円盤型混合機、コニカルブレンダー及びロールミキサー等の公知の混合装置を用いて均一混合する方法が挙げられる。 The water-absorbent resin composition of the present invention can be obtained by mixing the crosslinked polymer (A) and the water-insoluble alumina-containing fine particles (c). As a mixing method, a cylindrical mixer, a screw mixer, a screw extruder, a turbulizer, a Nauta mixer, a double arm kneader, a fluid mixer, a V mixer, a mince mixer, a ribbon type Examples of the method include uniform mixing using known mixing devices such as mixers, air-flow mixers, rotary disk mixers, conical blenders and roll mixers.
　架橋重合体（Ａ）と水不溶性アルミナ含有微粒子（ｃ）との混合は、架橋重合体（Ａ）の撹拌下に水不溶性アルミナ含有微粒子（ｃ）を加えることが好ましい。加えられる水不溶性アルミナ含有微粒子（ｃ）は、水及び／又は溶剤と同時に添加しても良い。水不溶性アルミナ含有微粒子（ｃ）を水及び／又は溶剤と同時に添加する場合、水不溶性アルミナ含有微粒子（ｃ）を水及び／又は溶剤に分散した分散液を添加することができ、作業性等の観点から分散液を添加することが好ましく、水分散液を添加することが更に好ましい。分散液を添加する場合、噴霧又は滴下して添加することが好ましい。 In mixing the crosslinked polymer (A) with the water-insoluble alumina-containing fine particles (c), it is preferable to add the water-insoluble alumina-containing fine particles (c) while stirring the crosslinked polymer (A). The water-insoluble alumina-containing fine particles (c) to be added may be added simultaneously with the water and / or the solvent. When water-insoluble alumina-containing fine particles (c) are added simultaneously with water and / or a solvent, a dispersion in which water-insoluble alumina-containing fine particles (c) are dispersed in water and / or a solvent can be added. From the viewpoint, it is preferable to add a dispersion, and it is more preferable to add an aqueous dispersion. When adding a dispersion, it is preferable to add by spraying or dripping.
　水不溶性アルミナ含有微粒子（ｃ）の分散液を用いる場合、分散液に含まれる水不溶性アルミナ含有微粒子（ｃ）の含有量は、分散液の合計重量に対して５～７０％重量％が好ましく、更に好ましくは１０～６０重量％である。 When a dispersion of water-insoluble alumina-containing microparticles (c) is used, the content of water-insoluble alumina-containing microparticles (c) in the dispersion is preferably 5 to 70% by weight based on the total weight of the dispersion, More preferably, it is 10 to 60% by weight.
　水不溶性アルミナ含有微粒子（ｃ）の分散液は、従来公知の方法により水及び／又は溶剤中で素原料を反応させ直接造粒して得られる分散液を用いてもよいし、微粒子を水及び／又は溶剤中に機械的に分散して得られる分散液を用いてもよい。
　分散液の安定性の観点から、水及び／又は溶剤中で素原料を反応させ直接造粒して得られる分散液を用いることが好ましい。水不溶性アルミナ含有微粒子（ｃ）の分散液は、水性コロイド液（ゾル）として市販品を入手することができる。
　なお分散液には、必要に応じて任意の安定化剤等の添加剤が含まれていても良い。安定化剤としては、例えば、市販の界面活性剤や分散剤、市販の酸化合物［リン酸（塩）、ホウ酸（塩）、アルカリ金属（塩）及びアルカリ土類金属（塩）、ヒドロキシカルボン酸（塩）、脂肪酸（塩）等］が挙げられる。 The dispersion of the water-insoluble alumina-containing fine particles (c) may be a dispersion obtained by directly granulating the raw material in water and / or a solvent according to a method known in the prior art, and A dispersion obtained by mechanical dispersion in a solvent may be used.
From the viewpoint of the stability of the dispersion, it is preferable to use a dispersion obtained by directly granulating the raw material in water and / or a solvent and granulating it. A dispersion of the water-insoluble alumina-containing fine particles (c) can be obtained as a commercial colloidal liquid (sol).
The dispersion may contain, if necessary, additives such as any stabilizer. Examples of the stabilizer include commercially available surfactants and dispersants, commercially available acid compounds [phosphoric acid (salt), boric acid (salt), alkali metal (salt) and alkaline earth metal (salt), hydroxy carbon Acids (salts), fatty acids (salts), etc.] can be mentioned.
　架橋重合体（Ａ）と水不溶性アルミナ含有微粒子（ｃ）を混合する際の温度は、吸収性能の観点から、１０～１５０℃が好ましく、更に好ましくは２０～１００℃、特に好ましくは２５～８０℃である。 The temperature when mixing the crosslinked polymer (A) and the water-insoluble alumina-containing fine particles (c) is preferably 10 to 150 ° C., more preferably 20 to 100 ° C., particularly preferably 25 to 80 ° from the viewpoint of absorption performance. ° C.
　架橋重合体（Ａ）と水不溶性アルミナ含有微粒子（ｃ）を混合した後、更に加熱処理を行ってもよい。加熱温度は、樹脂粒子の耐壊れ性の観点から好ましくは２５～１８０℃、更に好ましくは３０～１７５℃、特に好ましくは３５～１７０℃である。１８０℃以下の加熱であれば蒸気を利用した間接加熱が可能であり設備上有利である。また、加熱を行わない場合、併用する水及び溶剤が吸水性樹脂中に過剰に残存することとなり、吸収性能が悪くなる場合がある。吸水性樹脂中に残存する水、溶剤の量としては、吸水性樹脂１００重量部あたり、１～１０重量部が好ましい。吸水性樹脂中に残存する水、溶剤の量は、ＪＩＳＫ００６７－１９９２（化学製品の減量及び残分試験法）に準拠し、加熱減量法により得ることができる。
　架橋重合体（Ａ）と水不溶性アルミナ含有微粒子（ｃ）との混合後に加熱する場合、加熱時間は加熱温度により適宜設定することができるが、吸収性能の観点から、好ましくは５～６０分、更に好ましくは１０～４０分である。架橋重合体（Ａ）と水不溶性アルミナ含有微粒子（ｃ）とを混合して得られる吸水性樹脂を、最初に用いた水不溶性アルミナ含有微粒子と同種又は異種の水不溶性アルミナ含有微粒子を用いて、更に表面処理することも可能である。 After mixing the crosslinked polymer (A) and the water-insoluble alumina-containing fine particles (c), heat treatment may be further performed. The heating temperature is preferably 25 to 180 ° C., more preferably 30 to 175 ° C., particularly preferably 35 to 170 ° C. from the viewpoint of the breakage resistance of the resin particles. In the case of heating at 180 ° C. or lower, indirect heating using steam is possible, which is advantageous in equipment. In addition, when the heating is not performed, the water and the solvent to be used in combination may be excessively left in the water absorbent resin, and the absorption performance may be deteriorated. The amount of water and solvent remaining in the water-absorbent resin is preferably 1 to 10 parts by weight per 100 parts by weight of the water-absorbent resin. The amount of water and solvent remaining in the water-absorbent resin can be obtained by a heating loss method in accordance with JIS K 0067-1992 (Method for testing weight loss and residue of chemical products).
In the case of heating after mixing of the crosslinked polymer (A) and the water-insoluble alumina-containing fine particles (c), the heating time can be appropriately set by the heating temperature, but from the viewpoint of absorption performance, preferably 5 to 60 minutes, More preferably, it is 10 to 40 minutes. A water-absorbent resin obtained by mixing the crosslinked polymer (A) and the water-insoluble alumina-containing fine particles (c) with the water-insoluble alumina-containing fine particles of the same or different type as the water-insoluble alumina-containing fine particles used first It is also possible to surface-treat.
　本発明の吸水性樹脂組成物は、架橋重合体（Ａ）と水不溶性アルミナ含有微粒子（ｃ）との混合後に、篩別して粒度調整して用いても良い。粒度調整して得られた粒子の平均粒経は、好ましくは１００～６００μｍ、更に好ましくは２００～５００μｍである。微粒子の含有量は少ない方が好ましく、１００μｍ以下の粒子の含有量は３重量％以下であることが好ましく、１５０μｍ以下の粒子の含有量が３重量％以下であることが更に好ましい。 The water-absorbent resin composition of the present invention may be sieved to adjust the particle size after mixing the crosslinked polymer (A) and the water-insoluble alumina-containing fine particles (c). The average particle size of the particles obtained by adjusting the particle size is preferably 100 to 600 μm, more preferably 200 to 500 μm. The content of the fine particles is preferably small, the content of particles of 100 μm or less is preferably 3% by weight or less, and the content of particles of 150 μm or less is more preferably 3% by weight or less.
　本発明の吸水性樹脂組成物において、水不溶性アルミナ含有微粒子（ｃ）の含有量は、吸水性樹脂組成物の用途に応じて調整することができるが、架橋重合体（Ａ）の重量に基づいて、０．０１～１重量％が好ましく、更に好ましくは０．０２～０．８重量％、特に好ましくは０．０５～０．５重量％である。この範囲にあると吸水性樹脂組成物の通液性が良好となり更に好ましい。 In the water-absorbent resin composition of the present invention, the content of the water-insoluble alumina-containing fine particles (c) can be adjusted according to the application of the water-absorbent resin composition, but based on the weight of the crosslinked polymer (A). Thus, 0.01 to 1% by weight is preferable, more preferably 0.02 to 0.8% by weight, and particularly preferably 0.05 to 0.5% by weight. Within this range, the liquid permeability of the water-absorbent resin composition becomes good, which is further preferable.
　本発明の吸水性樹脂組成物は、水溶性アルミニウム塩（ｄ）を含む。水溶性アルミニウム塩（ｄ）としては、アルミン酸塩［アルミン酸ナトリウム、アルミン酸カリウム、及びこれらの水和物等］、アルミニウムの硫酸塩及びその複塩［硫酸アルミニウム、硫酸カリウムアルミニウム、硫酸ナトリウムアルミニウム及びこれらの水和物等］、アルミニウムの塩化物［塩化アルミニウム、ポリ塩化アルミニウム、及びこれらの水和物等］、及びアルミニウムの有機酸塩［乳酸アルミニウム、酢酸アルミニウム、及びこれらの水和物等］等が挙げられる。（ｄ）は１種を単独で用いても良いし、２種以上を併用しても良い。 The water absorbent resin composition of the present invention contains a water soluble aluminum salt (d). Examples of water-soluble aluminum salts (d) include aluminates (sodium aluminate, potassium aluminate, and hydrates thereof, etc.), sulfates of aluminum and double salts thereof (aluminum sulfate, potassium aluminum sulfate, sodium aluminum sulfate) And their hydrates], chlorides of aluminum [aluminium chloride, polyaluminium chloride, and hydrates thereof], and organic acid salts of aluminum [aluminium lactate, aluminum acetate, and hydrates thereof] Etc. One kind of (d) may be used alone, or two or more kinds may be used in combination.
　本発明における水溶性アルミニウム塩（ｄ）は、２０℃で１０ｇ／１００ｇＨ２Ｏ以上の水溶解度を持つ結晶性の塩であることが好ましい。
　水溶性アルミニウム塩（ｄ）の水溶解度は、より好ましくは２０ｇ／１００ｇＨ２Ｏ以上であり、更に好ましくは２５ｇ／１００ｇＨ２Ｏ以上である。水溶解度が１０ｇ／１００ｇＨ２Ｏより小さいと、架橋重合体（Ａ）との均一混合が難しくなり吸水性樹脂組成物の通液性が悪化する。 The water-soluble aluminum salt (d) in the present invention is preferably a crystalline salt having a water solubility of 10 g / 100 g H 2 O or more at 20 ° C.
The water solubility of the water-soluble aluminum salt (d) is more preferably 20 g / 100 g H 2 O or more, still more preferably 25 g / 100 g H 2 O or more. When the water solubility is smaller than 10 g / 100 g H 2 O, uniform mixing with the crosslinked polymer (A) is difficult, and the liquid permeability of the water-absorbent resin composition is deteriorated.
　（ｄ）が非結晶性であると、吸水性樹脂の膨潤時にアルミニウム水溶性塩の溶出が起こりやすく吸収性能が悪化するため、（ｄ）は結晶性であることが好ましい。（ｄ）が水高溶解性の結晶性の塩であれば、吸水性樹脂の表面がアルミニウム水溶性塩の微結晶で被覆されやすくなり、通液性に特に優れる。 When (d) is non-crystalline, elution of the aluminum water-soluble salt easily occurs at the time of swelling of the water-absorbent resin, and the absorption performance is deteriorated. Therefore, (d) is preferably crystalline. If (d) is a highly water-soluble crystalline salt, the surface of the water-absorbent resin is likely to be coated with microcrystalline aluminum water-soluble salt, and the liquid permeability is particularly excellent.
　水溶性アルミニウム塩（ｄ）のうち、結晶性で水溶性が高く、かつ入手が容易である観点から、アルミニウムの硫酸塩及びその複塩が好ましく、硫酸アルミニウム１４～１８水和物及び硫酸アルミニウムナトリウム１２水和物が更に好ましい。 Among the water-soluble aluminum salts (d), aluminum sulfates and double salts thereof are preferred from the viewpoint of high crystallinity and high water solubility and easy availability, aluminum sulfate 14-18 hydrate and aluminum sodium sulfate More preferred is dodecahydrate.
　本発明の吸水性樹脂組成物は、架橋重合体（Ａ）と水溶性アルミニウム塩（ｄ）とを混合することで得ることができる。混合方法としては、円筒型混合機、スクリュー型混合機、スクリュー型押出機、タービュライザー、ナウター型混合機、双腕型ニーダー、流動式混合機、Ｖ型混合機、ミンチ混合機、リボン型混合機、気流型混合機、回転円盤型混合機、コニカルブレンダー及びロールミキサー等の公知の混合装置を用いて均一混合する方法が挙げられる。 The water-absorbent resin composition of the present invention can be obtained by mixing the crosslinked polymer (A) and the water-soluble aluminum salt (d). As a mixing method, a cylindrical mixer, a screw mixer, a screw extruder, a turbulizer, a Nauta mixer, a double arm kneader, a fluid mixer, a V mixer, a mince mixer, a ribbon type Examples of the method include uniform mixing using known mixing devices such as mixers, air-flow mixers, rotary disk mixers, conical blenders and roll mixers.
　架橋重合体（Ａ）と水溶性アルミニウム塩（ｄ）との混合は、架橋重合体（Ａ）の撹拌下に水溶性アルミニウム塩（ｄ）を加えることが好ましい。加えられる水溶性アルミニウム塩（ｄ）は、水及び／又は溶剤と同時に添加しても良い。水溶性アルミニウム塩（ｄ）を水及び／又は溶剤と同時に添加する場合、作業性及び通液性等の観点から水溶性アルミニウム塩（ｄ）を水及び／又は溶剤に溶解した溶液を添加することができ、水を含有する溶媒に溶解した水溶液を添加することが更に好ましい。溶液を添加する場合、噴霧又は滴下して添加することが好ましい。 In mixing the crosslinked polymer (A) and the water-soluble aluminum salt (d), it is preferable to add the water-soluble aluminum salt (d) while stirring the crosslinked polymer (A). The water-soluble aluminum salt (d) to be added may be added simultaneously with the water and / or the solvent. When water-soluble aluminum salt (d) is added simultaneously with water and / or solvent, a solution of water-soluble aluminum salt (d) dissolved in water and / or solvent is added from the viewpoint of workability and liquid permeability. It is further preferred to add an aqueous solution dissolved in a solvent containing water. When adding a solution, it is preferable to add by spraying or dripping.
　水溶性アルミニウム塩（ｄ）の溶液を用いる場合、溶液に含まれる水溶性アルミニウム塩（ｄ）の含有量は、溶液の合計重量に対して５～７０％重量％が好ましく、更に好ましくは１０～６０重量％である。 When a solution of the water-soluble aluminum salt (d) is used, the content of the water-soluble aluminum salt (d) contained in the solution is preferably 5 to 70% by weight based on the total weight of the solution, more preferably 10 to It is 60% by weight.
　架橋重合体（Ａ）と水溶性アルミニウム塩（ｄ）を混合する際の温度は特に限定されないが、１０～１５０℃が好ましく、更に好ましくは２０～１００℃、特に好ましくは２５～８０℃である。 The temperature at which the cross-linked polymer (A) and the water-soluble aluminum salt (d) are mixed is not particularly limited, but is preferably 10 to 150 ° C., more preferably 20 to 100 ° C., particularly preferably 25 to 80 ° C. .
　架橋重合体（Ａ）と水溶性アルミニウム塩（ｄ）を混合した後、更に加熱処理を行ってもよい。加熱温度は、樹脂粒子の耐壊れ性の観点から好ましくは２５～１８０℃、更に好ましくは３０～１７５℃、特に好ましくは３５～１７０℃である。１８０℃以下の加熱であれば蒸気を利用した間接加熱が可能であり設備上有利である。また、加熱を行わない場合、併用する水及び溶剤が吸水性樹脂中に過剰に残存することとなり、吸収性能が悪くなる場合がある。吸水性樹脂中に残存する水、溶剤の量としては、吸水性樹脂１００重量部あたり、１～１０重量部が好ましい。吸水性樹脂中に残存する水、溶剤の量は、ＪＩＳＫ００６７－１９９２（化学製品の減量及び残分試験法）に準拠し、加熱減量法により得ることができる。
　架橋重合体（Ａ）と水溶性アルミニウム塩（ｄ）との混合後に加熱する場合、加熱時間は加熱温度により適宜設定することができるが、吸収性能の観点から、好ましくは５～６０分、更に好ましくは１０～４０分である。架橋重合体（Ａ）と水溶性アルミニウム塩（ｄ）とを混合して得られる吸水性樹脂を、最初に用いた水溶性アルミニウム塩と同種又は異種の水溶性アルミニウム塩を用いて、更に表面処理することも可能である。 After mixing the crosslinked polymer (A) and the water-soluble aluminum salt (d), heat treatment may be further performed. The heating temperature is preferably 25 to 180 ° C., more preferably 30 to 175 ° C., particularly preferably 35 to 170 ° C. from the viewpoint of the breakage resistance of the resin particles. In the case of heating at 180 ° C. or lower, indirect heating using steam is possible, which is advantageous in equipment. In addition, when the heating is not performed, the water and the solvent to be used in combination may be excessively left in the water absorbent resin, and the absorption performance may be deteriorated. The amount of water and solvent remaining in the water-absorbent resin is preferably 1 to 10 parts by weight per 100 parts by weight of the water-absorbent resin. The amount of water and solvent remaining in the water-absorbent resin can be obtained by a heating loss method in accordance with JIS K 0067-1992 (Method for testing weight loss and residue of chemical products).
When heating is carried out after mixing of the crosslinked polymer (A) and the water-soluble aluminum salt (d), the heating time can be appropriately set according to the heating temperature, but from the viewpoint of absorption performance, preferably 5 to 60 minutes, further Preferably, it is 10 to 40 minutes. A water-absorbent resin obtained by mixing a crosslinked polymer (A) and a water-soluble aluminum salt (d) is further surface-treated with a water-soluble aluminum salt of the same or different type as the water-soluble aluminum salt used first. It is also possible.
　本発明の吸水性樹脂組成物は、架橋重合体（Ａ）と水溶性アルミニウム塩（ｄ）との混合後に、篩別して粒度調整して用いても良い。粒度調整して得られた粒子の平均粒経は、好ましくは１００～６００μｍ、更に好ましくは２００～５００μｍである。微粒子の含有量は少ない方が好ましく、１００μｍ以下の粒子の含有量は３重量％以下であることが好ましく、１５０μｍ以下の粒子の含有量が３重量％以下であることが更に好ましい。 The water-absorbent resin composition of the present invention may be sieved to adjust the particle size after mixing the crosslinked polymer (A) and the water-soluble aluminum salt (d). The average particle size of the particles obtained by adjusting the particle size is preferably 100 to 600 μm, more preferably 200 to 500 μm. The content of the fine particles is preferably small, the content of particles of 100 μm or less is preferably 3% by weight or less, and the content of particles of 150 μm or less is more preferably 3% by weight or less.
　本発明の吸水性樹脂組成物において、水溶性アルミニウム塩（ｄ）の含有量は、吸水性樹脂組成物の用途に応じて調整することができるが、架橋重合体（Ａ）の重量に基づいて、０．０５～５重量％が好ましく、更に好ましくは０．１～４重量％、特に好ましくは０．２～３重量％である。この範囲にあると吸水性樹脂組成物の通液性が良好となり更に好ましい。ここで、水溶性アルミニウム塩（ｄ）が、水和物である場合、水和水を除く質量を基準とする。 In the water-absorbent resin composition of the present invention, the content of the water-soluble aluminum salt (d) can be adjusted according to the application of the water-absorbent resin composition, but based on the weight of the crosslinked polymer (A). 0.05 to 5% by weight, more preferably 0.1 to 4% by weight, and particularly preferably 0.2 to 3% by weight. Within this range, the liquid permeability of the water-absorbent resin composition becomes good, which is further preferable. Here, when water-soluble aluminum salt (d) is a hydrate, it is based on the mass except hydration water.
　本発明の吸水性樹脂組成物は、架橋重合体（Ａ）と、水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）を混合することにより得ることができるが、水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）は、架橋重合体（Ａ）に同時に添加してもよいし、別々に添加してもよい。被覆均一性及び通液性の観点から、同時に添加されることが好ましい。同時に添加とは、上述の乾燥、粉砕、表面架橋等の各工程において一度に又は別々に添加されることを意味する。
　架橋重合体（Ａ）の表面が有機表面架橋剤（ｅ）により架橋された構造を有する場合、水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）は、前記の有機表面架橋剤（ｅ）での表面架橋の前、後のいずれの段階で行ってもよいが、吸水性樹脂組成物の加圧下での吸収性能の観点から、水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）の少なくとも一方は有機表面架橋剤（ｅ）の添加と同時又は以前に添加することが好ましく、水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）の少なくとも一方を有機表面架橋剤（ｅ）の添加と同時に添加することが更に好ましく、水不溶性アルミナ含有微粒子（ｃ）、水溶性アルミニウム塩（ｄ）及び有機表面架橋剤（ｅ）を同時に添加することが特に好ましい。これら３成分を表面架橋前に添加、特に同時に添加することで、驚くべきことに表面架橋層に水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）の複合被膜が形成され、初期膨潤における耐ブロッキング性や通液性及びゲル強度を更に高めることができることを見出した。 The water-absorbent resin composition of the present invention can be obtained by mixing the crosslinked polymer (A) with the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d). (C) and the water-soluble aluminum salt (d) may be added simultaneously or separately to the crosslinked polymer (A). It is preferable to simultaneously add from the viewpoint of coating uniformity and liquid permeability. The simultaneous addition means that they are added at one time or separately in each step such as the above-mentioned drying, grinding, surface crosslinking and the like.
When the surface of the crosslinked polymer (A) has a structure crosslinked by the organic surface crosslinking agent (e), the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) Although it may be carried out at any stage before or after surface crosslinking in e), from the viewpoint of the absorption performance under pressure of the water-absorbent resin composition, the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt At least one of (d) is preferably added simultaneously with or before the addition of the organic surface crosslinking agent (e), and at least one of the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) is organically crosslinked It is more preferable to add simultaneously with the addition of the agent (e), and it is particularly preferable to simultaneously add the water-insoluble alumina-containing fine particles (c), the water-soluble aluminum salt (d) and the organic surface crosslinking agent (e). Preferred. The addition of these three components before surface crosslinking, in particular simultaneously, surprisingly forms a composite film of water-insoluble alumina-containing fine particles (c) and a water-soluble aluminum salt (d) in the surface crosslinked layer, and causes initial swelling. Were found to be able to further enhance the blocking resistance, the liquid permeability and the gel strength.
　本発明の吸水性樹脂組成物は、架橋重合体（Ａ）の表面アルミニウム被覆率が６０～１００％である。表面アルミニウム被覆率は、初期膨潤における耐ブロッキング性や通液性及びゲル強度の観点から６５～１００％であることが好ましく、更に好ましくは７０～１００％、特に好ましくは７５～１００％である。表面アルミニウム被覆率を６０～１００％とするには、水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）の添加量を上述の範囲に調節することにより行うことができる。表面アルミニウム被覆率は水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）による被覆状態を示す指標で、後述のエネルギー分散型Ｘ線分析法を用いたアルミニウム元素マッピングにより測定することができる。 In the water-absorbent resin composition of the present invention, the surface aluminum coverage of the crosslinked polymer (A) is 60 to 100%. The surface aluminum coverage is preferably 65 to 100%, more preferably 70 to 100%, and particularly preferably 75 to 100%, from the viewpoints of blocking resistance and liquid permeability and gel strength in initial swelling. In order to make the surface aluminum coverage 60 to 100%, the addition amount of the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) can be adjusted to the above-mentioned range. The surface aluminum coverage is an index showing the coating state by the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) and can be measured by aluminum element mapping using energy dispersive X-ray analysis described later. .
　本発明の吸水性樹脂組成物は、更に炭素数４以下の多価アルコール（ｆ）を含んでもよい。炭素数４以下の多価アルコール（ｆ）としては、エチレングリコール、プロピレングリコール、１，３－プロパンジオール、グリセリン、１，４－ブタンジオール等が挙げられる。これらの内、安全性や入手の容易さの観点から、プロピレングリコール及びグリセリンが好ましく、更に好ましいのはプロピレングリコールである。（ｆ）は１種を単独で用いても良いし、２種以上を併用しても良い。 The water-absorbent resin composition of the present invention may further contain a polyhydric alcohol (f) having 4 or less carbon atoms. Examples of the polyhydric alcohol (f) having 4 or less carbon atoms include ethylene glycol, propylene glycol, 1,3-propanediol, glycerin, 1,4-butanediol and the like. Among these, propylene glycol and glycerin are preferable in terms of safety and availability, and propylene glycol is more preferable. As (f), one type may be used alone, or two or more types may be used in combination.
　炭素数４以下の多価アルコール（ｆ）の使用量（重量％）は、吸収性能及び通液性の観点から架橋重合体（Ａ）の重量に基づいて、０．０５～５が好ましく、更に好ましくは０．１～３、特に好ましくは０．２～２である。 The amount (% by weight) of the polyhydric alcohol (f) having 4 or less carbon atoms is preferably 0.05 to 5 based on the weight of the crosslinked polymer (A) from the viewpoint of absorption performance and liquid permeability. It is preferably 0.1 to 3, particularly preferably 0.2 to 2.
　炭素数４以下の多価アルコール（ｆ）を含む場合、任意の工程で添加してもよいが、通液性の観点から水溶性アルミニウム塩（ｄ）と同時に添加することが更に好ましく、水不溶性アルミナ含有微粒子（ｃ）、水溶性アルミニウム塩（ｄ）及び有機表面架橋剤（ｅ）を同時に添加することが特に好ましい。（ｆ）を用いることにより、水溶性アルミニウム塩（ｄ）の吸水性樹脂表面への析出速度を制御でき、被覆率及び通液性が向上する。 When the polyhydric alcohol (f) having 4 or less carbon atoms is contained, it may be added in any step, but from the viewpoint of liquid permeability, addition simultaneously with the water-soluble aluminum salt (d) is more preferable, and water insoluble It is particularly preferable to simultaneously add the alumina-containing fine particles (c), the water-soluble aluminum salt (d) and the organic surface crosslinking agent (e). By using (f), the deposition rate of the water-soluble aluminum salt (d) on the surface of the water-absorbent resin can be controlled, and the coverage and liquid permeability are improved.
　本発明の吸水性樹脂組成物は、更に疎水性物質（ｇ）を含有してもよい。疎水性物質（ｇ）としては、炭化水素基を含有する疎水性物質（ｇ１）、フッ素原子をもつ炭化水素基を含有する疎水性物質（ｇ２）及びポリシロキサン構造をもつ疎水性物質（ｇ３）等が含まれる。 The water absorbent resin composition of the present invention may further contain a hydrophobic substance (g). The hydrophobic substance (g) includes a hydrophobic substance containing a hydrocarbon group (g1), a hydrophobic substance containing a hydrocarbon group having a fluorine atom (g2), and a hydrophobic substance having a polysiloxane structure (g3) Etc. are included.
　炭化水素基を含有する疎水性物質（ｇ１）としては、ポリオレフィン樹脂、ポリオレフィン樹脂誘導体、ポリスチレン樹脂、ポリスチレン樹脂誘導体、ワックス、長鎖脂肪酸エステル、長鎖脂肪酸及びその塩、長鎖脂肪族アルコール、長鎖脂肪族アミド及びこれらの２種以上の混合物等が含まれる。 As a hydrophobic substance (g1) containing a hydrocarbon group, polyolefin resin, polyolefin resin derivative, polystyrene resin, polystyrene resin derivative, wax, long chain fatty acid ester, long chain fatty acid and salts thereof, long chain aliphatic alcohol, long And chain aliphatic amides and mixtures of two or more thereof.
　ポリオレフィン樹脂としては、炭素数２～４のオレフィン｛エチレン、プロピレン、イソブチレン及びイソプレン等｝を必須構成単量体（オレフィンの含有量はポリオレフィン樹脂の重量に基づいて、少なくとも５０重量％）としてなる重量平均分子量１０００～１００万の重合体｛たとえば、ポリエチレン、ポリプロピレン、ポリイソブチレン、ポリ（エチレン－イソブチレン）及びイソプレン等｝が挙げられる。 The weight of the polyolefin resin is an olefin having 2 to 4 carbon atoms {ethylene, propylene, isobutylene, isoprene, etc.} as an essential constituent monomer (the content of the olefin is at least 50% by weight based on the weight of the polyolefin resin) Polymers having an average molecular weight of 1,000 to 1,000,000 (eg, polyethylene, polypropylene, polyisobutylene, poly (ethylene-isobutylene) and isoprene etc.) can be mentioned.
　ポリオレフィン樹脂誘導体としては、ポリオレフィン樹脂にカルボキシ基（－ＣＯＯＨ）や１，３－オキソ－２－オキサプロピレン（－ＣＯＯＣＯ－）等を導入した重量平均分子量１０００～１００万の重合体｛たとえば、ポリエチレン熱減成体、ポリプロピレン熱減成体、マレイン酸変性ポリエチレン、塩素化ポリエチレン、マレイン酸変性ポリプロピレン、エチレン－アクリル酸共重合体、エチレン－無水マレイン酸共重合体、イソブチレン－無水マレイン酸共重合体、マレイン化ポリブタジエン、エチレン－酢酸ビニル共重合体及びエチレン－酢酸ビニル共重合体のマレイン化物等｝が挙げられる。 As a polyolefin resin derivative, a polymer having a weight average molecular weight of 1000 to 1,000,000 obtained by introducing a carboxy group (-COOH), 1,3-oxo-2-oxapropylene (-COCOO-) or the like into a polyolefin resin {eg polyethylene heat Degradation body, polypropylene thermal degradation body, maleic acid modified polyethylene, chlorinated polyethylene, maleic acid modified polypropylene, ethylene-acrylic acid copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, maleated And polybutadiene, ethylene-vinyl acetate copolymer, and maleated ethylene-vinyl acetate copolymer, etc.}.
　ポリスチレン樹脂としては、重量平均分子量１０００～１００万の重合体等が使用できる。　 As the polystyrene resin, a polymer having a weight average molecular weight of 1,000 to 1,000,000 can be used.
ポリスチレン樹脂誘導体としては、スチレンを必須構成単量体（スチレンの含有量は、ポリスチレン誘導体の重量に基づいて、少なくとも５０重量％）としてなる重量平均分子量１０００～１００万の重合体｛たとえば、スチレン－無水マレイン酸共重合体、スチレン－ブタジエン共重合体及びスチレン－イソブチレン共重合体等｝が挙げられる。 As a polystyrene resin derivative, a polymer having a weight average molecular weight of 1000 to 1,000,000 and a polymer having a weight average molecular weight of 1000 to 1,000,000, in which styrene is an essential constituent monomer (the content of styrene is at least 50% by weight based on the weight of the polystyrene derivative) And maleic anhydride copolymer, styrene-butadiene copolymer, and styrene-isobutylene copolymer.
　ワックスとしては、融点５０～２００℃のワックス｛たとえば、パラフィンワックス、ミツロウ、カルバナワックス及び牛脂等｝が挙げられる。 Waxes include waxes having a melting point of 50 to 200 ° C. (eg, paraffin wax, beeswax, carbana wax, tallow, etc.).
　長鎖脂肪酸エステルとしては、炭素数８～３０の脂肪酸と炭素数１～１２のアルコールとのエステル｛たとえば、ラウリン酸メチル、ラウリン酸エチル、ステアリン酸メチル、ステアリン酸エチル、オレイン酸メチル、オレイン酸エチル、グリセリンラウリン酸モノエステル、グリセリンステアリン酸モノエステル、グリセリンオレイン酸モノエステル、ペンタエリスリットラウリン酸モノエステル、ペンタエリスリットステアリン酸モノエステル、ペンタエリスリットオレイン酸モノエステル、ソルビットラウリン酸モノエステル、ソルビットステアリン酸モノエステル、ソルビットオレイン酸モノエステル、ショ糖パルミチン酸モノエステル、ショ糖パルミチン酸ジエステル、ショ糖パルミチン酸トリエステル、ショ糖ステアリン酸モノエステル、ショ糖ステアリン酸ジエステル、ショ糖ステアリン酸トリエステル及び牛脂等｝が挙げられる。 As long-chain fatty acid esters, esters of fatty acids having 8 to 30 carbon atoms and alcohols having 1 to 12 carbon atoms {eg methyl laurate, ethyl laurate, methyl stearate, ethyl stearate, methyl oleate, oleic acid Ethyl, glycerine laurate monoester, glycerine stearate monoester, glycerine oleate monoester, pentaerythritol dilaurate monoester, pentaerythritol stearate monoester, pentaerythritol oleate monoester, sorbit laurate monoester, Sorbit stearic acid monoester, Sorbit oleic acid monoester, Sucrose palmitic acid monoester, Sucrose palmitic acid diester, Sucrose palmitic acid triester, Sucrose stearic acid moester Ester, sucrose stearic acid diester, sucrose stearic acid triester, and beef tallow} and the like.
　長鎖脂肪酸及びその塩としては、炭素数８～３０の脂肪酸｛たとえば、ラウリン酸、パルミチン酸、ステアリン酸、オレイン酸、ダイマー酸及びベヘニン酸等｝が挙げられ、その塩としては亜鉛、カルシウム、マグネシウム又はアルミニウム（以下、それぞれＺｎ、Ｃａ、Ｍｇ、Ａｌと略す）との塩｛たとえば、パルミチン酸Ｃａ、パルミチン酸Ａｌ、ステアリン酸Ｃａ、ステアリン酸Ｍｇ、ステアリン酸Ａｌ等｝が挙げられる。 Examples of long chain fatty acids and salts thereof include fatty acids having 8 to 30 carbon atoms (eg, lauric acid, palmitic acid, stearic acid, oleic acid, dimer acid and behenic acid etc.), and salts thereof include zinc, calcium, Salts with magnesium or aluminum (hereinafter abbreviated as Zn, Ca, Mg and Al, respectively) {eg, Ca palmitate, Al palmitate, Ca stearate, Mg stearate, Al stearate etc.} can be mentioned.
　長鎖脂肪族アルコールとしては、炭素数８～３０の脂肪族アルコール｛たとえば、ラウリルアルコール、パルミチルアルコール、ステアリルアルコール、オレイルアルコール等｝が挙げられる。吸収性物品の耐モレ性の観点等から、パルミチルアルコール、ステアリルアルコール、オレイルアルコールが好ましく、さらに好ましくはステアリルアルコールである。 The long chain aliphatic alcohol includes aliphatic alcohols having 8 to 30 carbon atoms (eg, lauryl alcohol, palmityl alcohol, stearyl alcohol, oleyl alcohol etc.). From the viewpoint of moisture resistance of the absorbent article, palmityl alcohol, stearyl alcohol and oleyl alcohol are preferable, and stearyl alcohol is more preferable.
　長鎖脂肪族アミドとしては、炭素数８～３０の長鎖脂肪族一級アミンと炭素数１～３０の炭化水素基を有するカルボン酸とのアミド化物、アンモニア又は炭素数１～７の１級アミンと炭素数８～３０の長鎖脂肪酸とのアミド化物、炭素数８～３０の脂肪族鎖を少なくとも１つ有する長鎖脂肪族二級アミンと炭素数１～３０のカルボン酸とのアミド化物及び炭素数１～７の脂肪族炭化水素基を２個有する二級アミンと炭素数８～３０の長鎖脂肪酸とのアミド化物が挙げられる。 As the long chain aliphatic amide, an amidated compound of a long chain aliphatic primary amine having 8 to 30 carbon atoms and a carboxylic acid having a hydrocarbon group having 1 to 30 carbon atoms, ammonia, or a primary amine having 1 to 7 carbon atoms Amidated with a long chain fatty acid having 8 to 30 carbon atoms, an amidated long chain aliphatic secondary amine having at least one aliphatic chain having 8 to 30 carbon atoms and a carboxylic acid having 1 to 30 carbon atoms, An amidated product of a secondary amine having two aliphatic hydrocarbon groups having 1 to 7 carbon atoms and a long chain fatty acid having 8 to 30 carbon atoms can be mentioned.
　炭素数８～３０の長鎖脂肪族一級アミンと炭素数１～３０の炭化水素基を有するカルボン酸とのアミド化物としては、１級アミンとカルボン酸とが１：１で反応した物と１：２で反応した物に分けられる。１：１で反応した物としては、酢酸Ｎ－オクチルアミド、酢酸Ｎ－ヘキサコシルアミド、ヘプタコサン酸Ｎ－オクチルアミド及びヘプタコサン酸Ｎ－ヘキサコシルアミド等が挙げられる。１：２で反応したものとしては、二酢酸Ｎ－オクチルアミド、二酢酸Ｎ－ヘキサコシルアミド、ジヘプタコサン酸Ｎ－オクチルアミド及びジヘプタコサン酸Ｎ－ヘキサコシルアミド等が挙げられる。なお、１級アミンとカルボン酸とが１：２で反応した物の場合、使用するカルボン酸は、同一でも異なっていてもよい。 As an amidated compound of a long-chain aliphatic primary amine having 8 to 30 carbon atoms and a carboxylic acid having a hydrocarbon group having 1 to 30 carbon atoms, one obtained by reacting a primary amine and a carboxylic acid at a ratio of 1 to 1 : It is divided into the thing which reacted by 2. As a product reacted at 1: 1, acetic acid N-octylamide, acetic acid N-hexacosylamide, heptacosanoic acid N-octylamide, heptacosanoic acid N-hexacosylamide and the like can be mentioned. Examples of the reaction at 1: 2 include diacetic acid N-octylamide, diacetic acid N-hexacosylamide, diheptacosanic acid N-octylamide, and diheptacosanic acid N-hexacosylamide. In the case where the primary amine and the carboxylic acid are reacted at 1: 2, the carboxylic acids used may be the same or different.
　アンモニア又は炭素数１～７の１級アミンと炭素数８～３０の長鎖脂肪酸とのアミド化物としては、アンモニア又は１級アミンとカルボン酸とが１：１で反応した物と１：２で反応した物に分けられる。１：１で反応した物としては、ノナン酸アミド、ノナン酸メチルアミド、ノナン酸Ｎ－ヘプチルアミド、ヘプタコサン酸アミド、ヘプタコサン酸Ｎ－メチルアミド、ヘプタコサン酸Ｎ－ヘプチルアミド及びヘプタコサン酸Ｎ－ヘキサコシルアミド等が挙げられる。１：２で反応したものとしては、ジノナン酸アミド、ジノナン酸Ｎ－メチルアミド、ジノナン酸Ｎ－ヘプチルアミド、ジオクタデカン酸アミド、ジオクタデカン酸Ｎ－エチルアミド、ジオクタデカン酸Ｎ－ヘプチルアミド、ジヘプタコサン酸アミド、ジヘプタコサン酸Ｎ－メチルアミド、ジヘプタコサン酸Ｎ－ヘプチルアミド及びジヘプタコサン酸Ｎ－ヘキサコシルアミド等が挙げられる。なお、アンモニア又は１級アミンとカルボン酸とが１：２で反応した物としては、使用するカルボン酸は、同一でも異なっていてもよい。 As the amidated product of ammonia or a primary amine having 1 to 7 carbon atoms and a long chain fatty acid having 8 to 30 carbon atoms, the product obtained by reacting ammonia or a primary amine with carboxylic acid in a ratio of 1: 1 can be used. It is divided into the reaction products. As a product reacted at 1: 1, nonanoic acid amide, nonanoic acid methylamide, nonanoic acid N-heptylamide, heptacosanoic acid amide, heptacosanoic acid N-methylamide, heptacosanoic acid N-heptylamide and heptacosanoic acid N-hexacosylamide Etc. As a product reacted 1: 2: dinonanoic acid amide, dinonanoic acid N-methylamide, dinonanoic acid N-heptylamide, dioctadecanoic acid amide, dioctadecanoic acid N-ethylamide, dioctadecanoic acid N-heptylamide, diheptacosanoic acid amide And diheptacosanoic acid N-methylamide, diheptacosanoic acid N-heptylamide, and diheptacosanoic acid N-hexacosylamide. In addition, as a product in which ammonia or a primary amine and a carboxylic acid are reacted at 1: 2, the carboxylic acid to be used may be the same or different.
　炭素数８～３０の脂肪族鎖を少なくとも１つ有する長鎖脂肪族二級アミンと炭素数１～３０のカルボン酸とのアミド化物としては、酢酸Ｎ－メチルオクチルアミド、酢酸Ｎ－メチルヘキサコシルアミド、酢酸Ｎ－オクチルヘキサコシルアミド、酢酸Ｎ－ジヘキサコシルアミド、ヘプタコサン酸Ｎ－メチルオクチルアミド、ヘプタコサン酸Ｎ－メチルヘキサコシルアミド、ヘプタコサン酸Ｎ－オクチルヘキサコシルアミド及びヘプタコサン酸Ｎ－ジヘキサコシルアミド等が挙げられる。 Examples of the amidated compound of a long chain aliphatic secondary amine having at least one aliphatic chain having 8 to 30 carbon atoms and a carboxylic acid having 1 to 30 carbon atoms include acetic acid N-methyloctylamide and acetic acid N-methylhexaco Luamide, acetic acid N-octylhexacosylamide, acetic acid N-dihexacosylamide, heptacosanoic acid N-methyloctylamide, heptacosanoic acid N-methylhexacosylamide, heptacosanoic acid N-octylhexacosylamide and heptacosane Acid N-dihexacosylamide and the like.
　炭素数１～７の脂肪族炭化水素基を２個有する二級アミンと炭素数８～３０の長鎖脂肪酸とのアミド化物としては、ノナン酸Ｎ－ジメチルアミド、ノナン酸Ｎ－メチルヘプチルアミド、ノナン酸Ｎ－ジヘプチルアミド、ヘプタコサン酸Ｎ－ジメチルアミド、ヘプタコサン酸Ｎ－メチルヘプチルアミド及びヘプタコサン酸Ｎ－ジヘプチルアミド等が挙げられる。 As an amidated compound of a secondary amine having two aliphatic hydrocarbon groups having 1 to 7 carbon atoms and a long chain fatty acid having 8 to 30 carbon atoms, nonanoic acid N-dimethylamide, nonanoic acid N-methylheptylamide, Nonanoic acid N-diheptylamide, heptacosanoic acid N-dimethylamide, heptacosanoic acid N-methylheptylamide, heptacosanoic acid N-diheptylamide and the like can be mentioned.
　フッ素原子をもつ炭化水素基を含有する疎水性物質（ｇ２）としては、パーフルオロアルカン、パーフルオロアルケン、パーフルオロアリール、パーフルオロアルキルエーテル、パーフルオロアルキルカルボン酸、パーフルオロアルキルアルコール及びこれらの２種以上の混合物等が含まれる。 As the hydrophobic substance (g2) containing a hydrocarbon group having a fluorine atom, perfluoroalkanes, perfluoroalkenes, perfluoroaryls, perfluoroalkylethers, perfluoroalkylcarboxylic acids, perfluoroalkylalcohols and two of them Mixtures of species or more are included.
　ポリシロキサン構造をもつ疎水性物質（ｇ３）としては、ポリジメチルシロキサン、ポリエーテル変性ポリシロキサン｛ポリオキシエチレン変性ポリシロキサン及びポリ（オキシエチレン・オキシプロピレン）変性ポリシロキサン等｝、カルボキシ変性ポリシロキサン、エポキシ変性ポリシロキサン、アミノ変性ポリシロキサン、アルコキシ変性ポリシロキサン等及びこれらの混合物等が含まれる。 Examples of the hydrophobic substance (g3) having a polysiloxane structure include polydimethylsiloxane, polyether-modified polysiloxane {polyoxyethylene-modified polysiloxane and poly (oxyethylene · oxypropylene) -modified polysiloxane etc.}, carboxy-modified polysiloxane, Epoxy-modified polysiloxane, amino-modified polysiloxane, alkoxy-modified polysiloxane and the like and mixtures thereof are included.
　疎水性物質（ｇ）のＨＬＢ値は、１～１０が好ましく、さらに好ましくは２～８、特に好ましくは３～７である。この範囲であると、初期膨潤時の耐ブロッキング性がさらに良好となる。なお、ＨＬＢ値は、親水性－疎水性バランス（ＨＬＢ）値を意味し、小田法（新・界面活性剤入門、１９７頁、藤本武彦、三洋化成工業株式会社発行、１９８１年発行）により求められる。 The HLB value of the hydrophobic substance (g) is preferably 1 to 10, more preferably 2 to 8, and particularly preferably 3 to 7. Within this range, the blocking resistance at the time of initial swelling is further improved. The HLB value means the hydrophilic-hydrophobic balance (HLB) value, and can be determined by the Oda method (new surfactant introduction, page 197, published by Takehiko Fujimoto, Sanyo Chemical Industries, Ltd., published in 1981). .
　疎水性物質（ｇ）のうち、初期膨潤時の耐ブロッキング性の観点から、炭化水素基を含有する疎水性物質（ｇ１）が好ましく、より好ましくは長鎖脂肪酸エステル、長鎖脂肪酸及びその塩、長鎖脂肪族アルコール並びに長鎖脂肪族アミドであり、さらに好ましくはソルビットステアリン酸エステル、ショ糖ステアリン酸エステル、ステアリン酸、ステアリン酸Ｍｇ、ステアリン酸Ｃａ、ステアリン酸Ｚｎ及びステアリン酸Ａｌ、特に好ましくはショ糖ステアリン酸エステル及びステアリン酸Ｍｇであり、最も好ましくはショ糖ステアリン酸エステルである。 Among the hydrophobic substances (g), from the viewpoint of blocking resistance at the time of initial swelling, hydrophobic substances (g1) containing a hydrocarbon group are preferable, and long chain fatty acid esters, long chain fatty acids and salts thereof, Long-chain aliphatic alcohols and long-chain aliphatic amides, more preferably Sorbit stearic acid ester, sucrose stearic acid ester, stearic acid, stearic acid Mg, stearic acid Ca, stearic acid Zn and stearic acid Al, particularly preferably Sucrose stearate and Mg stearate, most preferably sucrose stearate.
　疎水性物質（ｇ）の使用量（重量％）は、吸収性能及び初期膨潤時の耐ブロッキング性の観点から架橋重合体（Ａ）の重量に基づいて、０．００１～１が好ましく、更に好ましくは０．００５～０．５、特に好ましくは０．０１～０．３である。 The amount (% by weight) of the hydrophobic substance (g) is preferably 0.001 to 1 based on the weight of the crosslinked polymer (A) from the viewpoint of absorption performance and blocking resistance at the time of initial swelling, more preferably Is from 0.005 to 0.5, particularly preferably from 0.01 to 0.3.
　疎水性物質（ｇ）を含む場合、任意の工程で添加してもよいが、吸収性能の観点から水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）の添加より前に添加されることが好ましく、架橋重合体（Ａ）の表面が有機表面架橋剤（ｅ）により架橋された構造を有する場合、疎水性物質（ｇ）は前記の有機表面架橋剤（ｅ）での表面架橋の前に添加されることが更に好ましい。 When the hydrophobic substance (g) is contained, it may be added in any step, but is added prior to the addition of the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) from the viewpoint of absorption performance. In the case where the surface of the crosslinked polymer (A) has a structure crosslinked by the organic surface crosslinking agent (e), the hydrophobic substance (g) is preferably the surface crosslinked by the organic surface crosslinking agent (e). More preferably it is added before.
　本発明の吸水性樹脂組成物は、必要に応じて、添加剤（例えば、公知（特開２００３－２２５５６５号及び特開２００６－１３１７６７号等に記載）の防腐剤、防かび剤、抗菌剤、酸化防止剤、紫外線吸収剤、着色剤、芳香剤、消臭剤、通液性向上剤及び有機質繊維状物等）を含むこともできる。これらの添加剤を含有させる場合、添加剤の含有量（重量％）は、架橋重合体（Ａ）の重量に基づいて、０．００１～１０が好ましく、更に好ましくは０．０１～５、特に好ましくは０．０５～１、最も好ましくは０．１～０．５である。 The water-absorbent resin composition of the present invention may contain, if necessary, additives (for example, known preservatives (described in JP-A 2003-225565 and JP-A 2006-131767) and the like, fungicides, antibacterial agents, Antioxidants, UV absorbers, colorants, fragrances, deodorants, liquid flow improvers, organic fibrous materials and the like can also be included. When these additives are contained, the content (% by weight) of the additive is preferably 0.001 to 10, more preferably 0.01 to 5, particularly preferably 0.01 to 5 based on the weight of the crosslinked polymer (A). Preferably, it is 0.05 to 1, most preferably 0.1 to 0.5.
　本発明の製造方法は、前記架橋重合体（Ａ）を、水不溶性アルミナ含有微粒子（ｃ）の水性コロイド液及び水溶性アルミニウム塩（ｄ）の水溶液を用いて表面処理した後、表面架橋する。水不溶性アルミナ含有微粒子（ｃ）の水性コロイド液及び水溶性アルミニウム塩（ｄ）の具体例は前述の通りである。それらの添加量や添加方法等についても前述の通りであるが、通液性の観点から、架橋重合体（Ａ）に水不溶性アルミナ含有微粒子（ｃ）の水性コロイド液、水溶性アルミニウム塩（ｄ）の水溶液、有機表面架橋剤（ｅ）、炭素数４以下の多価アルコールを同時に添加した後、加熱処理を行うことが更に好ましい。 In the production method of the present invention, the crosslinked polymer (A) is surface-treated using an aqueous colloidal solution of water-insoluble alumina-containing fine particles (c) and an aqueous solution of a water-soluble aluminum salt (d), and then surface cross-linked. Specific examples of the aqueous colloidal solution of the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) are as described above. The addition amounts and addition methods thereof are also as described above, but from the viewpoint of liquid permeability, an aqueous colloid solution of water-insoluble alumina-containing fine particles (c), a water-soluble aluminum salt (d) It is further preferable to carry out heat treatment after simultaneously adding the aqueous solution of (a), the organic surface crosslinking agent (e) and the polyhydric alcohol having 4 or less carbon atoms.
　本発明の吸水性樹脂組成物及び本発明の製造方法により得られる吸水性樹脂組成物（以下、これらを区別せず本発明の吸水性樹脂組成物と称す）の保水量（ｇ／ｇ）は、後述する方法で測定することができ、オムツの吸収量の観点から好ましくは２８以上であり、３３以上が更に好ましく、３５以上がより更に好ましい。また、上限値は、荷重下での吸収量の観点から、６０以下が好ましく、５５以下がさらに好ましく、５０以下がより更に好ましい。保水量は、架橋剤（ｂ）、有機表面架橋剤（ｅ）の使用量（重量％）で適宜調整することができる。 The water retention amount (g / g) of the water-absorbent resin composition of the present invention and the water-absorbent resin composition obtained by the production method of the present invention (hereinafter referred to as the water-absorbent resin composition of the present invention without distinction) It can be measured by the method described later and is preferably 28 or more, more preferably 33 or more, and still more preferably 35 or more from the viewpoint of the amount of absorption of diapers. The upper limit is preferably 60 or less, more preferably 55 or less, and still more preferably 50 or less from the viewpoint of the amount of absorption under load. The water retention amount can be appropriately adjusted by the amount (% by weight) of the crosslinking agent (b) and the organic surface crosslinking agent (e).
　本発明の吸水性樹脂組成物のゲル通液速度（ｍｌ／分）は、後述する方法で測定することができ、オムツの吸収速度の観点から好ましくは５～３００であり、１０～２８０が更に好ましく、特に好ましくは、１５～２５０である。ゲル通液速度は保水量と相反することが経験的に知られており、オムツの構成により高保水量が求められる場合と高ゲル通液速度が求められる場合とがある。 The gel flow rate (ml / min) of the water-absorbent resin composition of the present invention can be measured by the method described later, and is preferably 5 to 300 from the viewpoint of diaper absorption rate, and 10 to 280 is more preferable. Preferred and particularly preferred is 15 to 250. It is empirically known that the gel flow rate is contrary to the water retention amount, and there are cases where a high water retention amount is required or a high gel flow rate is required depending on the configuration of the diaper.
　本発明の吸水性樹脂組成物の見掛け密度（ｇ／ｍｌ）は、０．５０～０．８０が好ましく、更に好ましくは０．５２～０．７５、特に好ましくは０．５４～０．７０である。この範囲であると、吸収性物品の耐カブレ性が更に良好となる。吸水性樹脂組成物の見掛け密度は、ＪＩＳ　Ｋ７３６５：１９９９に準拠して、２５℃で測定される。 The apparent density (g / ml) of the water-absorbent resin composition of the present invention is preferably 0.50 to 0.80, more preferably 0.52 to 0.75, particularly preferably 0.54 to 0.70. is there. When it is in this range, the anti-crash resistance of the absorbent article is further improved. The apparent density of the water absorbing resin composition is measured at 25 ° C. in accordance with JIS K7365: 1999.
　本発明の吸水性樹脂組成物の初期膨潤時のブロッキング率は、０～５０％が好ましく、更に好ましくは０～４０％、特に好ましくは０～３０％である。この範囲であると、吸収体中で液拡散性が十分確保され、吸収性能が安定する。 The blocking ratio at the initial swelling of the water-absorbent resin composition of the present invention is preferably 0 to 50%, more preferably 0 to 40%, and particularly preferably 0 to 30%. Within this range, the liquid diffusivity is sufficiently ensured in the absorber, and the absorption performance is stabilized.
　本発明の吸水性樹脂組成物のゲル強度（ｋＮ／ｍ２）は、２．５以上が好ましく、更に好ましくは２．７以上である。この範囲であると、荷重下での通液性が十分確保され、吸収性能が安定する。 The gel strength (kN / m 2 ) of the water-absorbent resin composition of the present invention is preferably 2.5 or more, more preferably 2.7 or more. Within this range, the liquid permeability under load is sufficiently ensured, and the absorption performance is stabilized.
　本発明の吸水性樹脂組成物を用いて吸収体を得ることができる。吸収体としては、吸水性樹脂組成物を単独で用いても良く、他の材料と共に用いて吸収体としても良い。
　他の材料としては繊維状物等が挙げられる。繊維状物と共に用いた場合の吸収体の構造及び製造方法等は、公知のもの（特開２００３－２２５５６５号公報、特開２００６－１３１７６７号公報及び特開２００５－０９７５６９号公報等）と同様である。 An absorbent can be obtained using the water-absorbent resin composition of the present invention. As an absorber, a water-absorbent resin composition may be used alone, or may be used as an absorber together with other materials.
Other materials include fibrous materials and the like. The structure, manufacturing method and the like of the absorber when used together with the fibrous material are the same as those of known ones (Japanese Patent Application Laid-Open Nos. 2003-225565, 2006-131767 and 2005-097569, etc.) is there.
　上記繊維状物として好ましいのは、セルロース系繊維、有機系合成繊維及びセルロース系繊維と有機系合成繊維との混合物である。 Preferred as the fibrous material are cellulose fibers, organic synthetic fibers, and a mixture of cellulose fibers and organic synthetic fibers.
　セルロース系繊維としては、例えばフラッフパルプ等の天然繊維、ビスコースレーヨン、アセテート及びキュプラ等のセルロース系化学繊維が挙げられる。このセルロース系天然繊維の原料（針葉樹及び広葉樹等）、製造方法（ケミカルパルプ、セミケミカルパルプ、メカニカルパルプ及びＣＴＭＰ等）及び漂白方法等は特に限定されない。 Examples of cellulosic fibers include natural fibers such as fluff pulp, and cellulosic chemical fibers such as viscose rayon, acetate and cupra. There are no particular limitations on the raw materials (softwood and hardwoods, etc.) of this cellulose-based natural fiber, the production method (chemical pulp, semichemical pulp, mechanical pulp, CTMP, etc.) and the bleaching method.
　有機系合成繊維としては、例えばポリプロピレン系繊維、ポリエチレン系繊維、ポリアミド系繊維、ポリアクリロニトリル系繊維、ポリエステル系繊維、ポリビニルアルコール系繊維、ポリウレタン系繊維及び熱融着性複合繊維（融点の異なる上記繊維の少なくとも２種を鞘芯型、偏芯型、並列型等に複合化された繊維、上記繊維の少なくとも２種をブレンドした繊維及び上記繊維の表層を改質した繊維等）が挙げられる。 Examples of organic synthetic fibers include polypropylene fibers, polyethylene fibers, polyamide fibers, polyacrylonitrile fibers, polyester fibers, polyvinyl alcohol fibers, polyurethane fibers and heat fusible composite fibers (the above-mentioned fibers having different melting points) Fibers in which at least two of them are combined with a sheath-core type, eccentric type, parallel type, etc., fibers obtained by blending at least two of the above fibers, and fibers obtained by modifying the surface layer of the above fibers).
　これらの繊維状物の内で好ましいのは、セルロース系天然繊維、ポリプロピレン系繊維、ポリエチレン系繊維、ポリエステル系繊維、熱融着性複合繊維及びこれらの混合繊維であり、更に好ましいのは、得られた吸水剤の吸水後の形状保持性に優れるという点で、フラッフパルプ、熱融着性複合繊維及びこれらの混合繊維である。 Among these fibrous materials, preferred are cellulose-based natural fibers, polypropylene-based fibers, polyethylene-based fibers, polyester-based fibers, heat-sealable composite fibers and mixed fibers thereof, and more preferred are fibers obtained It is a fluff pulp, a heat-fusible composite fiber, and a mixed fiber thereof in that it is excellent in the shape-retaining property after water absorption of the water-absorbing agent.
　上記繊維状物の長さ、太さについては特に限定されず、長さは１～２００ｍｍ、太さは０．１～１００デニールの範囲であれば好適に使用することができる。形状についても繊維状であれば特に限定されず、細い円筒状、スプリットヤーン状、ステープル状、フィラメント状及びウェブ状等が例示される。 The length and thickness of the fibrous material are not particularly limited, and can be suitably used if the length is in the range of 1 to 200 mm and the thickness is in the range of 0.1 to 100 denier. The shape is also not particularly limited as long as it is fibrous, and thin cylindrical, split yarn, staple, filament, web and the like are exemplified.
　吸水性樹脂組成物を、繊維状物と共に吸収体とする場合、吸水性樹脂組成物と繊維の重量比率（吸水性樹脂組成物の重量／繊維の重量）は４０／６０～９０／１０が好ましく、更に好ましくは７０／３０～８０／２０である。 When the water-absorbent resin composition is used as an absorbent together with the fibrous material, the weight ratio of the water-absorbent resin composition to the fibers (weight of water-absorbent resin composition / weight of fibers) is preferably 40/60 to 90/10. More preferably, it is 70/30 to 80/20.
　本発明の吸水性樹脂を用いて吸収性物品を得ることができる。具体的には、上記吸収体を用いる。吸収性物品としては、紙おむつや生理用ナプキン等の衛生用品のみならず、後述する各種水性液体の吸収や保持剤用途、ゲル化剤用途等の各種用途に使用されるものとして適用可能である。吸収性物品の製造方法等は、公知のもの（特開２００３－２２５５６５号公報、特開２００６－１３１７６７号公報及び特開２００５－０９７５６９号公報等に記載のもの）と同様である。 An absorbent article can be obtained using the water absorbent resin of the present invention. Specifically, the above-mentioned absorber is used. The absorbent articles are applicable not only to sanitary goods such as disposable diapers and sanitary napkins, but also to various uses such as absorption of various aqueous liquids to be described later, use as a holding agent, use as a gelling agent, and the like. The method for producing the absorbent article and the like are the same as known ones (described in JP-A-2003-225565, JP-A-2006-131767 and JP-A-2005-097569).
　以下、実施例及び比較例により本発明を更に説明するが、本発明はこれらに限定されるものではない。以下、特に定めない限り、部は重量部、％は重量％を示す。なお、吸水性樹脂組成物の生理食塩水に対する保水量、荷重下吸収量及びゲル通液速度、表面アルミニウム被覆率、初期膨潤時のブロッキング率、ゲル強度は以下の方法により測定した。 EXAMPLES The present invention will be further described by the following Examples and Comparative Examples, but the present invention is not limited thereto. Hereinafter, unless otherwise specified, parts indicate parts by weight and% indicates% by weight. The water retention amount, absorption amount under load, gel flow rate, surface aluminum coverage, blocking rate at initial swelling, gel strength of the water-absorbent resin composition to a saline solution were measured by the following methods.
＜保水量の測定方法＞
　目開き６３μｍ（ＪＩＳ　Ｚ８８０１－１：２００６）のナイロン網で作製したティーバッグ（縦２０ｃｍ、横１０ｃｍ）に測定試料１．００ｇを入れ、生理食塩水（食塩濃度０．９％）１，０００ｍｌ中に無撹拌下、１時間浸漬した後引き上げて、１５分間吊るして水切りした。その後、ティーバッグごと、遠心分離器にいれ、１５０Ｇで９０秒間遠心脱水して余剰の生理食塩水を取り除き、ティーバックを含めた重量（ｈ１）を測定し次式から保水量を求めた。なお、使用した生理食塩水及び測定雰囲気の温度は２５℃±２℃であった。
保水量（ｇ／ｇ）＝（ｈ１）－（ｈ２）
　なお、（ｈ２）は、測定試料の無い場合について上記と同様の操作により計測したティーバックの重量である。 <Measurement method of water retention amount>
In a tea bag (length 20 cm, width 10 cm) prepared with a nylon mesh with an opening of 63 μm (JIS Z8801-1: 2006), 1.00 g of the measurement sample is placed, and in 1,000 ml of physiological saline (saline concentration 0.9%) After immersion for 1 hour with no stirring, it was pulled up and suspended for 15 minutes to drain. Thereafter, each tea bag was placed in a centrifuge and centrifuged at 150 G for 90 seconds to remove excess saline, and the weight (h1) including the tea bag was measured to determine the water retention amount from the following equation. In addition, the temperature of the used physiological saline and measurement atmosphere was 25 degreeC +/- 2 degreeC.
Water holding capacity (g / g) = (h1)-(h2)
In addition, (h2) is the weight of the tea bag measured by the same operation as described above when there is no measurement sample.
＜荷重下吸収量の測定方法＞
　目開き６３μｍ（ＪＩＳ　Ｚ８８０１－１：２００６）のナイロン網を底面に貼った円筒型プラスチックチューブ（内径：２５ｍｍ、高さ：３４ｍｍ）内に、３０メッシュふるいと６０メッシュふるいを用いて２５０～５００μｍの範囲にふるい分けした測定試料０．１６ｇを秤量し、円筒型プラスチックチューブを垂直にしてナイロン網上に測定試料がほぼ均一厚さになるように整えた後、この測定試料の上に分銅（重量：２１０．６ｇ、外径：２４．５ｍｍ、）を乗せた。この円筒型プラスチックチューブ全体の重量（Ｍ１）を計量した後、生理食塩水（食塩濃度０．９％）６０ｍｌの入ったシャーレ（直径：１２ｃｍ）の中に測定試料及び分銅の入った円筒型プラスチックチューブを垂直に立ててナイロン網側を下面にして浸し、６０分静置した。６０分後に、円筒型プラスチックチューブをシャーレから引き上げ、これを斜めに傾けて底部に付着した水を一箇所に集めて水滴として垂らすことで余分な水を除去した後、測定試料及び分銅の入った円筒型プラスチックチューブ全体の重量（Ｍ２）を計量し、次式から荷重下吸収量を求めた。なお、使用した生理食塩水及び測定雰囲気の温度は２５℃±２℃であった。
荷重下吸収量（ｇ／ｇ）＝｛（Ｍ２）－（Ｍ１）｝／０．１６ <Method of measuring absorption under load>
In a cylindrical plastic tube (inner diameter: 25 mm, height: 34 mm) having a nylon mesh of 63 μm (JIS Z8801-1: 2006) attached to the bottom, 250 to 500 μm using a 30 mesh sieve and a 60 mesh sieve After weighing 0.16 g of the measurement sample sifted into a range and arranging the cylindrical plastic tube vertically so that the measurement sample has a substantially uniform thickness on a nylon mesh, a weight (weight: 210.6 g, outer diameter: 24.5 mm,). After weighing the entire weight (M1) of this cylindrical plastic tube, a cylindrical plastic containing the measurement sample and weight in a petri dish (diameter: 12 cm) containing 60 ml of physiological saline (0.9% salt concentration) The tube was stood vertically, dipped on the nylon mesh side as the lower surface, and allowed to stand for 60 minutes. After 60 minutes, the cylindrical plastic tube was pulled up from the petri dish, and this was inclined to collect water attached to the bottom at one place and dripped as water droplets to remove excess water, and then the measurement sample and weight entered The weight (M2) of the entire cylindrical plastic tube was measured, and the amount of absorption under load was determined from the following equation. In addition, the temperature of the used physiological saline and measurement atmosphere was 25 degreeC +/- 2 degreeC.
Absorption under load (g / g) = {(M2)-(M1)} / 0.16
＜ゲル通液速度の測定方法＞
　図１及び図２で示される器具を用いて以下の操作により測定した。
　測定試料０．３２ｇを１５０ｍｌ生理食塩水１（食塩濃度０．９％）に３０分間浸漬して膨潤ゲル粒子２を調製した。そして、垂直に立てた円筒３｛直径（内径）２５．４ｍｍ、長さ４０ｃｍ、底部から６０ｍｌの位置及び４０ｍｌの位置にそれぞれ目盛り線４及び目盛り線５が設けてある。｝の底部に、金網６（目開き１０６μｍ、ＪＩＳ Ｚ８８０１－１：２００６）と、開閉自在のコック７（通液部の内径５ｍｍ）とを有する濾過円筒管内に、コック７を閉鎖した状態で、調製した膨潤ゲル粒子２を生理食塩水と共に移した後、この膨潤ゲル粒子２の上に円形金網８（目開き１５０μｍ、直径２５ｍｍ）が金網面に対して垂直に結合する加圧軸９（重さ２２ｇ、長さ４７ｃｍ）を金網と膨潤ゲル粒子とが接触するように載せ、更に加圧軸９におもり１０（８８．５ｇ）を載せ、１分間静置した。引き続き、コック７を開き、濾過円筒管内の液面が６０ｍｌ目盛り線４から４０ｍｌ目盛り線５になるのに要する時間（Ｔ１；秒）を計測し、次式よりゲル通液速度（ｍｌ／分）を求めた。
　ゲル通液速度（ｍｌ／分）＝２０ｍｌ×６０／（Ｔ１－Ｔ２）
　なお、使用する生理食塩水及び測定雰囲気の温度は２５℃±２℃で行い、Ｔ２は測定試料の無い場合について上記と同様の操作により計測した時間である。 <Method of measuring gel flow rate>
It measured by the following operations using the instrument shown by FIG. 1 and FIG.
Swelled gel particles 2 were prepared by immersing 0.32 g of the measurement sample in 150 ml of physiological saline 1 (saline concentration: 0.9%) for 30 minutes. A scale 4 and a scale 5 are respectively provided at a vertically standing cylinder 3 {diameter (inner diameter) 25.4 mm, length 40 cm, 60 ml from the bottom and 40 ml from the bottom. } In the state which closed the cock 7 in the filtration cylindrical pipe which has the wire mesh 6 (aperture 106 μm, JIS Z8801-1: 2006) and the openable / closable cock 7 (inner diameter 5 mm of the liquid passing portion) at the bottom of}. After transferring the prepared swollen gel particles 2 together with physiological saline, a pressure shaft 9 (weight) in which a circular wire mesh 8 (150 μm mesh, 25 mm diameter) is vertically bonded to the surface of the swollen gel particles 2 22 g, 47 cm in length, was placed so that the wire mesh and the swollen gel particles were in contact with each other, and further, a weight 10 (88.5 g) was placed on the pressure shaft 9 and allowed to stand for 1 minute. Subsequently, the cock 7 is opened, and the time (T1; seconds) required for the liquid level in the filtration cylinder to change from 60 ml division line 4 to 40 ml division line 5 is measured, and gel flow rate (ml / min) I asked for.
Gel flow rate (ml / min) = 20 ml x 60 / (T1-T2)
In addition, the temperature of the physiological saline to be used and measurement atmosphere was 25 degreeC +/- 2 degreeC, and T2 is the time measured by operation similar to the above about the case without a measurement sample.
＜表面アルミニウム被覆率の測定方法＞
　カーボンテープを貼った試料台に３０メッシュふるいと６０メッシュふるいを用いて２５０～５００μｍの範囲にふるい分けした測定試料を１０粒以上、粒子同士が重ならないように固定し、Ｏｘｆｏｒｄ社製エネルギー分散型Ｘ線分析（ＥＤＳ分析）装置を付属した、ＪＥＯＬ社製電界放出型走査電子顕微鏡「ＪＳＭ－７０００」にセットした。倍率を１５０倍にし、粒子１粒を画面に表示し、元素マッピングモードでＥＤＳ分析を行った。対象元素であるアルミニウムの検出面積をＳ１、吸水性樹脂組成物の特徴元素（吸水性樹脂組成物の主成分がポリアクリル酸ナトリウム塩である場合は、ナトリウム）の検出面積をＳ０とし、次式から表面アルミニウム被覆率を求めた。
　表面アルミニウム被覆率（％）＝（Ｓ１／Ｓ０）×１００
　１種類の測定試料につき無作為に５粒の測定を行い、算術平均値を測定試料の被覆率とした。なお、検出面積Ｓ０及びＳ１として、それぞれの検出強度の頻度分布をヒストグラムとして出力した値を用いた。 <Method of measuring surface aluminum coverage>
Fix 10 samples or more of the measurement sample sieved in the range of 250 to 500 μm using a 30 mesh sieve and a 60 mesh sieve on a sample stand with a carbon tape so that the particles do not overlap with each other. It was set in a JEOL field emission scanning electron microscope “JSM-7000” attached with a line analysis (EDS analysis) apparatus. The magnification was increased by 150 times, one particle was displayed on the screen, and EDS analysis was performed in the elemental mapping mode. Assuming that the detection area of aluminum which is the target element is S1, and the detection area of the feature element of the water-absorbent resin composition (sodium when the main component of the water-absorbent resin composition is polyacrylic acid sodium salt), the detection area is S0. The surface aluminum coverage was determined from.
Surface aluminum coverage (%) = (S1 / S0) × 100
Five particles were measured at random for one type of measurement sample, and the arithmetic mean value was taken as the coverage of the measurement sample. In addition, the value which output frequency distribution of each detection intensity as a histogram was used as detection area S0 and S1.
＜初期膨潤時のブロッキング率（％）＞
　吸水性樹脂のうち、目開き４．０ｍｍ、直径８ｃｍの金属ふるいを５回タッピングしてパスする粒子を測定試料とした。この測定試料１．５ｇを、直径５ｃｍ、高さ７ｃｍのＰＰ（ポリプロピレン）製ディスポカップに均一になるように入れて、生理食塩水０．１４ｇを均一にスプレー添加し１分間静置した。４．０ｍｍの金属ふるいで５回タッピングして、金属ふるいに残った測定試料の重量（ＯＷ）を計測し、金属ふるいに残った測定試料と通過した測定試料の合計重量（ＴＷ）を計測し、次式から初期膨潤時のブロッキング率（％）を算出した。
　（初期膨潤時のブロッキング率（％））＝（ＯＷ）×１００／（ＴＷ）
１種類の測定試料につき３回の測定を行い、算術平均値を測定試料のブロッキング率とした。 <Blocking rate at initial swelling (%)>
Among the water-absorbent resins, particles which pass by tapping a metal sieve having an opening of 4.0 mm and a diameter of 8 cm five times were used as measurement samples. 1.5 g of this measurement sample was uniformly placed in a PP (polypropylene) disposable cup having a diameter of 5 cm and a height of 7 cm, 0.14 g of physiological saline was uniformly sprayed, and allowed to stand for 1 minute. Tapping five times with a 4.0 mm metal sieve to measure the weight (OW) of the measurement sample left on the metal sieve, and measure the total weight (TW) of the measurement sample left on the metal sieve and the measurement sample passed. The blocking ratio (%) at initial swelling was calculated from the following equation.
(Blocking ratio at initial swelling (%)) = (OW) × 100 / (TW)
Three measurements were performed for one type of measurement sample, and the arithmetic mean value was taken as the blocking rate of the measurement sample.
＜ゲル強度の測定方法＞
　人工尿［尿素２００重量部、塩化ナトリウム８０重量部、硫酸マグネシウム７水和物８重量部、塩化カルシウム２水和物３重量部、硫酸第二鉄７水和物２重量部、イオン交換水９７０４重量部］６０．０ｇを１００ｍｌビーカー（内径５ｃｍ）に量り取り、ＪＩＳ　Ｋ７２２４－１９９６に記載された操作と同様にして、測定試料２．０ｇを精秤して上記ビーカーに投入し、３０倍膨潤ゲルを作成した。この膨潤ゲルが乾燥しないように３０倍膨潤ゲルの入ったビーカーにラップをし、このビーカーを４０±２℃の雰囲気下で３時間、さらに２５±２℃の雰囲気下で０．５時間静置した後、ラップを取り外し、３０倍膨潤ゲルのゲル強度をカードメーター（たとえば、株式会社アイテックテクノエンジニアリング製カードメーター・マックスＭＥ－５００）を用いて測定した。なおカードメーターの条件は以下の通りである。
・感圧軸：８ｍｍ
・スプリング：１００ｇ用
・荷重：１００ｇ
・上昇速度：１インチ／７秒
・試験性質：破断
・測定時間：６秒
・測定雰囲気温度：２５±２℃   <Method of measuring gel strength>
Artificial urine [200 parts by weight of urea, 80 parts by weight of sodium chloride, 8 parts by weight of magnesium sulfate heptahydrate, 3 parts by weight of calcium chloride dihydrate, 2 parts by weight of ferric sulfate heptahydrate, ion exchanged water 9704 [Weighing parts] Weigh 60.0 g in a 100 ml beaker (inner diameter 5 cm), precisely weigh 2.0 g of the measurement sample, and put it in the beaker in the same manner as the operation described in JIS K7224-1996. I made a gel. Wrap the beaker with a 30-fold swelling gel so that this swelling gel does not dry, and allow this beaker to stand for 3 hours in an atmosphere of 40 ± 2 ° C, and for 0.5 hour in an atmosphere of 25 ± 2 ° C. Then, the wrap was removed, and the gel strength of the 30-fold swelling gel was measured using a card meter (for example, Card Meter Max ME-500 manufactured by ITEC Techno Engineering Co., Ltd.). The conditions for the card meter are as follows.
・ Pressure sensitive axis: 8 mm
・ Spring: For 100 g ・ Load: 100 g
-Rising speed: 1 inch / 7 seconds-Test properties: Break-Measuring time: 6 seconds-Measuring atmosphere temperature: 25 ± 2 ° C
＜実施例１＞
　アクリル酸（ａ１－１）｛三菱化学株式会社製、純度１００％｝１３１部、架橋剤（ｂ－１）｛ペンタエリスリトールトリアリルエーテル、ダイソ－株式会社製｝０．４４部及び脱イオン水３６２部を攪拌・混合しながら３℃に保った。この混合物中に窒素を流入して溶存酸素量を１ｐｐｍ以下とした後、１％過酸化水素水溶液０．５部、２％アスコルビン酸水溶液１部及び２％の２，２’－アゾビスアミジノプロパンジハイドロクロライド水溶液１部を添加・混合して重合を開始させた。混合物の温度が８０℃に達した後、８０±２℃で約５時間重合することにより含水ゲルを得た。 Example 1
Acrylic acid (a1-1) {Mitsubishi Chemical Co., Ltd., purity 100%} 131 parts, Crosslinking agent (b-1) {pentaerythritol triallyl ether, 0.40 parts of Diso-Ltd.}, deionized water 362 The part was kept at 3 ° C. with stirring and mixing. After nitrogen is introduced into this mixture to make the amount of dissolved oxygen 1 ppm or less, 0.5 part of 1% aqueous hydrogen peroxide solution, 1 part of 2% aqueous ascorbic acid solution and 2% 2,2'-azobisamidinopropane One part of aqueous dihydrochloride solution was added and mixed to initiate polymerization. After the temperature of the mixture reached 80 ° C., a hydrogel was obtained by polymerizing at 80 ± 2 ° C. for about 5 hours.
　次にこの含水ゲルをミンチ機（ＲＯＹＡＬ社製１２ＶＲ－４００Ｋ）で細断しながら、４８．５％水酸化ナトリウム水溶液１０８部を添加して混合・中和し、中和ゲル（中和度：７２％）を得た。更に中和した含水ゲルを通気型乾燥機｛２００℃、風速２ｍ／秒｝で乾燥し、乾燥体を得た。乾燥体をジューサーミキサー（Ｏｓｔｅｒ社製ＯＳＴＥＲＩＺＥＲ　ＢＬＥＮＤＥＲ）にて粉砕した後、ふるい分けして、目開き７１０～１５０μｍの粒子径範囲に調整して、架橋重合体（Ａ－１）を得た。 Next, while this water-containing gel is shredded with a mincing machine (12 VR-400 K manufactured by ROYAL), 108 parts of a 48.5% aqueous sodium hydroxide solution is added to mix and neutralize, and the neutralized gel (degree of neutralization: 72%). Furthermore, the neutralized water-containing gel was dried by a ventilated drier {200 ° C., wind speed 2 m / sec} to obtain a dried product. The dried product was pulverized with a juicer mixer (OSTERIZER BLENDER manufactured by Oster) and sieved to adjust to a particle diameter range of 710 to 150 μm to obtain a crosslinked polymer (A-1).
　ついで、得られた架橋重合体（Ａ－１）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、これに水不溶性アルミナ含有微粒子（ｃ）としてのＬＵＤＯＸ　ＣＬ（シグマアルドリッチジャパン株式会社製）１．０部、有機表面架橋剤（ｅ）としてのエチレングリコールジグリシジルエーテル０．１部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール１．０部、及び水１．６部を混合した混合液と、水溶性アルミニウム塩（ｄ）としての硫酸ナトリウムアルミニウム１２水和物０．６部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール０．５部及び水１．４部を混合した混合液を同時に添加し、均一混合した後、１３０℃で３０分間加熱して、本発明の吸水性樹脂組成物（Ｐ－１）を得た。
＜ＬＵＤＯＸ　ＣＬの性状＞
アルミナ変性シリカの水分散コロイド液
固形分濃度３０％
個数基準平均一次粒子径１２ｎｍ Next, while stirring 100 parts of the obtained crosslinked polymer (A-1) at high speed (high speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed: 2000 rpm), LUDOX CL (as water-insoluble alumina-containing fine particles (c)) 1.0 part of Sigma-Aldrich Japan Co., Ltd., 0.1 part of ethylene glycol diglycidyl ether as organic surface crosslinking agent (e), and 1.0 part of propylene glycol as polyhydric alcohol having 4 or less carbon atoms (f) And a mixed solution of 1.6 parts of water, 0.6 parts of sodium aluminum sulfate dodecahydrate as water-soluble aluminum salt (d), and propylene glycol as polyhydric alcohol (f) having 4 or less carbon atoms The mixed solution of 0.5 part and 1.4 part of water is simultaneously added and uniformly mixed, and then heated at 130 ° C. for 30 minutes to obtain the present invention. The water-absorbent resin composition (P-1) was obtained.
<Properties of LUDOX CL>
30% solid concentration of aqueous dispersion colloidal solution of alumina modified silica
Number-based average primary particle size 12 nm
＜実施例２＞
　実施例１と同様にして得られた架橋重合体（Ａ－１）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、これに水不溶性アルミナ含有微粒子（ｃ）としてのバイラールＡｌ－Ｌ７（多木化学株式会社製）４．０部、有機表面架橋剤（ｅ）としてのエチレングリコールジグリシジルエーテル０．１部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール０．５部、及び水１．１部を混合した混合液と、水溶性アルミニウム塩（ｄ）としての硫酸ナトリウムアルミニウム１２水和物０．６部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール０．５部及び水１．４部を混合した混合液を同時に添加し、均一混合した後、１３０℃で３０分間加熱して、本発明の吸水性樹脂組成物（Ｐ－２）を得た。
＜バイラールＡｌ－Ｌ７の性状＞
アルミナの水分散コロイド液
固形分濃度７％
個数基準平均一次粒子径５－１０ｎｍ範囲内 Example 2
While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c) Al-L7 (made by Taki Chemical Co., Ltd.) 4.0 parts as ethylene, 0.1 part of ethylene glycol diglycidyl ether as organic surface crosslinking agent (e), as polyhydric alcohol having 4 or less carbon atoms (f) A mixed solution of 0.5 parts of propylene glycol and 1.1 parts of water, and 0.6 parts of sodium aluminum sulfate dodecahydrate as a water-soluble aluminum salt (d), and a polyhydric alcohol having 4 or less carbon atoms A mixed solution of 0.5 parts of propylene glycol as (f) and 1.4 parts of water is simultaneously added, uniformly mixed, and then heated at 130 ° C. for 30 minutes to obtain the present invention. Water absorbent resin composition (P-2) was obtained.
<Properties of Viral Al-L7>
Aqueous dispersion of alumina in colloidal liquid solid concentration 7%
Number based average primary particle diameter in the range of 5-10 nm
＜実施例３＞
　実施例１と同様にして得られた架橋重合体（Ａ－１）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、これに水不溶性アルミナ含有微粒子（ｃ）としてのバイラールＡｌ－Ｃ２０（多木化学株式会社製）１．５部、有機表面架橋剤（ｅ）としてのエチレングリコールジグリシジルエーテル０．１部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール０．８部、及び水１．３部を混合した混合液と、水溶性アルミニウム塩（ｄ）としての硫酸ナトリウムアルミニウム１２水和物０．６部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール０．５部及び水１．４部を混合した混合液を同時に添加し、均一混合した後、１３０℃で３０分間加熱して、本発明の吸水性樹脂組成物（Ｐ－３）を得た。
＜バイラールＡｌ－Ｃ２０の性状＞
アルミナの水分散コロイド液
固形分濃度２０％
個数基準平均一次粒子径１５－２０ｎｍ範囲内 Example 3
While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c) Al-C20 (manufactured by Taki Chemical Co., Ltd.) as 1.5 parts, ethylene part diglycidyl ether as an organic surface crosslinking agent (e) 0.1 parts, as a polyhydric alcohol having 4 or less carbon atoms (f) Mixed liquid of 0.8 parts of propylene glycol and 1.3 parts of water, and 0.6 parts of sodium aluminum sulfate dodecahydrate as water-soluble aluminum salt (d), polyhydric alcohol having 4 or less carbon atoms A mixed solution of 0.5 parts of propylene glycol as (f) and 1.4 parts of water is simultaneously added, mixed uniformly, and then heated at 130 ° C. for 30 minutes to obtain To give a water absorbent resin composition (P-3).
<Properties of Viral Al-C20>
20% solid content concentration of alumina dispersed in water
Number based average primary particle diameter within 15-20 nm range
＜実施例４＞
　実施例１と同様にして得られた架橋重合体（Ａ－１）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、これに水不溶性アルミナ含有微粒子（ｃ）としてのバイラールＡＳ－Ｌ１０（多木化学株式会社製）３．０部、有機表面架橋剤（ｅ）としてのエチレングリコールジグリシジルエーテル０．１部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール０．５部、及び水１．１部を混合した混合液と、水溶性アルミニウム塩（ｄ）としての硫酸ナトリウムアルミニウム１２水和物０．６部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール０．５部及び水１．４部を混合した混合液を同時に添加し、均一混合した後、１３０℃で３０分間加熱して、本発明の吸水性樹脂組成物（Ｐ－４）を得た。
＜バイラールＡＳ－Ｌ１０の性状＞
ムライトの水分散コロイド液
固形分濃度１０％
個数基準平均一次粒子径５－５０ｎｍ範囲内 Example 4
While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c) 3.0 parts of Vyral AS-L10 (manufactured by Taki Chemical Co., Ltd.), 0.1 parts of ethylene glycol diglycidyl ether as an organic surface crosslinking agent (e), and a polyhydric alcohol having 4 or less carbon atoms (f) A mixed solution of 0.5 parts of propylene glycol and 1.1 parts of water, and 0.6 parts of sodium aluminum sulfate dodecahydrate as a water-soluble aluminum salt (d), and a polyhydric alcohol having 4 or less carbon atoms A mixed solution of 0.5 parts of propylene glycol as (f) and 1.4 parts of water is simultaneously added, mixed uniformly, and then heated at 130 ° C. for 30 minutes to obtain To give a water absorbent resin composition (P-4).
<Properties of Viral AS-L10>
10% solid concentration of aqueous dispersion of mullite in water
Number based average primary particle diameter within 5-50 nm range
＜実施例５＞
　実施例１と同様にして得られた架橋重合体（Ａ－１）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、これに水不溶性アルミナ含有微粒子（ｃ）としてのＬＵＤＯＸ　ＣＬ（シグマアルドリッチジャパン株式会社製）１．０部、有機表面架橋剤（ｅ）としてのエチレングリコールジグリシジルエーテル０．１部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール１．０部、及び水１．６部を混合した混合液を添加し、均一混合した後、１３０℃で３０分間加熱し、室温まで冷却した後、更に高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら水溶性アルミニウム塩（ｄ）としての硫酸ナトリウムアルミニウム１２水和物０．６部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール０．５部及び水１．４部を混合した混合液を同時に添加し、均一混合した後、１３０℃で３０分間加熱して、本発明の吸水性樹脂組成物（Ｐ－５）を得た。 Example 5
While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c) 1.0 part of LUDOX CL (manufactured by Sigma Aldrich Japan Co., Ltd.) as a component, 0.1 part of ethylene glycol diglycidyl ether as an organic surface crosslinking agent (e), propylene as a polyhydric alcohol having 4 or less carbon atoms (f) A mixed solution of 1.0 part of glycol and 1.6 parts of water is added, mixed uniformly, heated at 130 ° C. for 30 minutes, cooled to room temperature, and then stirred at high speed (high speed stirrer made by Hosokawa Micron Bulizer: 0.6 parts of sodium aluminum sulfate dodecahydrate as water-soluble aluminum salt (d) while rotating at 2000 rpm), charcoal A mixed solution of 0.5 parts of propylene glycol as a polyhydric alcohol (f) having a prime number of 4 or less and 1.4 parts of water is simultaneously added and uniformly mixed, and then heated at 130 ° C. for 30 minutes. The water-absorbent resin composition (P-5) was obtained.
＜実施例６＞
　実施例１と同様にして得られた架橋重合体（Ａ－１）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、これに水不溶性アルミナ含有微粒子（ｃ）としてのＬＵＤＯＸ　ＣＬ－Ｐ（グレース社製）０．７５部、有機表面架橋剤（ｅ）としてのエチレングリコールジグリシジルエーテル０．１部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール１．０部、及び水１．６部を混合した混合液と、水溶性アルミニウム塩（ｄ）としての硫酸ナトリウムアルミニウム１２水和物０．６部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール０．５部及び水１．４部を混合した混合液を同時に添加し、均一混合した後、１３０℃で３０分間加熱して、本発明の吸水性樹脂組成物（Ｐ－６）を得た。
＜ＬＵＤＯＸ　ＣＬ－Ｐの性状＞
アルミナ変性シリカの水分散コロイド液
固形分濃度４０％
個数基準平均一次粒子径２２ｎｍ Example 6
While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c) 0.75 parts of LUDOX CL-P (Grace Corporation) as a component, 0.1 parts of ethylene glycol diglycidyl ether as an organic surface crosslinking agent (e), propylene glycol as a polyhydric alcohol having 4 or less carbon atoms (f) A mixed solution of 1.0 part and 1.6 parts of water, 0.6 part of sodium aluminum sulfate dodecahydrate as water-soluble aluminum salt (d), polyhydric alcohol having 4 or less carbon atoms (f) The mixed solution of 0.5 parts of propylene glycol as a mixture and 1.4 parts of water is simultaneously added, mixed uniformly, and then heated at 130 ° C. for 30 minutes to obtain the water absorption of the present invention Functional resin composition (P-6) was obtained.
<Properties of LUDOX CL-P>
Aqueous dispersion of alumina modified silica in water 40% solid concentration
Number-based average primary particle diameter 22 nm
＜比較例１＞
　実施例１と同様にして得られた架橋重合体（Ａ－１）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、これに、水溶性アルミニウム塩（ｄ）としての硫酸ナトリウムアルミニウム１２水和物１．２部、有機表面架橋剤（ｅ）としてのエチレングリコールジグリシジルエーテル０．１部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール０．５部、及び水１．１部を混合した混合液を添加し、均一混合した後、１３０℃で３０分間加熱して、比較用の吸水性樹脂組成物（Ｒ－１）を得た。 Comparative Example 1
A water-soluble aluminum salt (d) was added to 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 while stirring at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm). 1.2 parts of sodium aluminum sulfate dodecahydrate, 0.1 parts of ethylene glycol diglycidyl ether as organic surface crosslinking agent (e), propylene glycol as a polyhydric alcohol having 4 or less carbon atoms (f). A mixed solution of 5 parts and 1.1 parts of water was added and uniformly mixed, followed by heating at 130 ° C. for 30 minutes to obtain a water-absorbent resin composition (R-1) for comparison.
＜比較例２＞
　実施例１と同様にして得られた架橋重合体（Ａ－１）１００部を高速攪拌（細川ミクロン製高速攪拌タービュライザー：回転数２０００ｒｐｍ）しながら、これに、水不溶性アルミナ含有微粒子（ｃ）としてのＬＵＤＯＸ　ＣＬ（シグマアルドリッチジャパン株式会社製）１．０部、有機表面架橋剤（ｅ）としてのエチレングリコールジグリシジルエーテル０．１部、炭素数４以下の多価アルコール（ｆ）としてのプロピレングリコール１．０部、及び水１．６部を混合した混合液を添加し、均一混合した後、１３０℃で３０分間加熱して、比較用の吸水性樹脂組成物（Ｒ－２）を得た。 Comparative Example 2
While stirring 100 parts of the crosslinked polymer (A-1) obtained in the same manner as in Example 1 at a high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), fine particles containing water-insoluble alumina (c 1.0 part of LUDOX CL (manufactured by Sigma Aldrich Japan Co., Ltd.), 0.1 part of ethylene glycol diglycidyl ether as organic surface crosslinking agent (e), and polyhydric alcohol having 4 or less carbon atoms (f) A mixed solution of 1.0 part of propylene glycol and 1.6 parts of water is added and uniformly mixed, and then heated at 130 ° C. for 30 minutes to obtain a water-absorbent resin composition (R-2) for comparison Obtained.
＜比較例３＞
　実施例１において、水不溶性アルミナ含有微粒子（ｃ）としてのＬＵＤＯＸ　ＣＬ（シグマアルドリッチジャパン株式会社製）１．０部をＬＵＤＯＸ　ＨＳ－３０（シグマアルドリッチジャパン株式会社製）１．０部に変更する以外は、実施例１と同様の操作を行い、比較用の吸水性樹脂組成物（Ｒ－３）を得た。
＜ＬＵＤＯＸ　ＨＳ－３０の性状＞
シリカの水分散コロイド液
固形分濃度３０％
個数基準平均一次粒子径１２ｎｍ Comparative Example 3
Except that, in Example 1, 1.0 part of LUDOX CL (manufactured by Sigma Aldrich Japan Co., Ltd.) as water-insoluble alumina-containing fine particles (c) is changed to 1.0 part of LUDOX HS-30 (manufactured by Sigma Aldrich Japan Co., Ltd.) In the same manner as in Example 1, a water-absorbent resin composition (R-3) for comparison was obtained.
<Properties of LUDOX HS-30>
30% solid concentration of colloidal silica liquid dispersed in water
Number-based average primary particle size 12 nm
　実施例１～６の吸水性樹脂組成物（Ｐ－１）～（Ｐ－６）及び比較例１～３の吸水性樹脂組成物（Ｒ－１）～（Ｒ－３）についての性能（保水量、荷重下吸収量及びゲル通液速度）、表面アルミニウム被覆率、初期膨潤時のブロッキング率、ゲル強度の評価結果を表１に示す。 Performance of water-absorbent resin compositions (P-1) to (P-6) of Examples 1 to 6 and water-absorbent resin compositions (R-1) to (R-3) of Comparative Examples 1 to 3 Table 1 shows the evaluation results of the amount of water, absorption under load and gel flow rate), surface aluminum coverage, blocking ratio at initial swelling, and gel strength.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１の結果から、実施例、比較例を通して保水量は良好であり有意な差は見られないが、実施例は荷重下吸収量とゲル通液性がともに良好であった。また、実施例は表面アルミニウム被覆率が高く、初期膨潤時のブロッキング率は有意に低い値を示した。更に、実施例はゲル強度が特に良好であった。一方、水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）を併用しない態様である比較例は、いずれも、初期膨潤時のブロッキング率は有意に高い値を示した。また、たとえ表面アルミニウム被覆率が高くても（比較例１）、荷重下吸収量とゲル通液性がともに低い値であった。 From the results in Table 1, the water retention amount was good through the Examples and Comparative Examples, and no significant difference was observed. However, in Examples, the absorption amount under load and the gel permeability were both good. In addition, in the examples, the surface aluminum coverage was high, and the blocking ratio at initial swelling showed a significantly low value. Furthermore, the examples had particularly good gel strength. On the other hand, in all of the comparative examples in which the water-insoluble alumina-containing fine particles (c) and the water-soluble aluminum salt (d) were not used in combination, the blocking ratio at initial swelling showed a significantly high value. Moreover, even if the surface aluminum coverage was high (comparative example 1), the absorption amount under load and the gel permeability were both low values.
　本発明の吸水性樹脂組成物は、初期膨潤における耐ブロッキング性や通液性及びゲル強度が高いため、各種の吸収体に適用することにより、吸収量が多く、逆戻り性や表面ドライ感に優れた吸収性物品にすることができることから、紙おむつ（子供用紙おむつ及び大人用紙おむつ等）、ナプキン（生理用ナプキン等）、紙タオル、パッド（失禁者用パッド及び手術用アンダーパッド等）及びペットシート（ペット尿吸収シート）等の衛生用品に好適に用いられ、特に紙おむつに最適である。なお、本発明の吸水性樹脂組成物は衛生用品のみならず、ペット尿吸収剤、携帯トイレの尿ゲル化剤、青果物等の鮮度保持剤、肉類及び魚介類のドリップ吸収剤、保冷剤、使い捨てカイロ、電池用ゲル化剤、植物及び土壌等の保水剤、結露防止剤、止水材やパッキング材並びに人工雪等、種々の用途にも有用である。 The water-absorbent resin composition of the present invention is high in blocking resistance, liquid permeability and gel strength in initial swelling, and therefore, when applied to various absorbers, it has a large amount of absorption and is excellent in reversion and surface dry feeling. Paper diapers (such as children's paper diapers and adult paper diapers), napkins (such as sanitary napkins), paper towels, pads (such as incontinent pads and surgical under pads), and pet sheets. It is suitably used for sanitary products such as (pet urine absorbing sheet) and is particularly suitable for disposable diapers. In addition, the water-absorbent resin composition of the present invention is not only used for sanitary products but also for pet urine absorbents, urine gelling agents for portable toilets, freshness maintenance agents such as fruits and vegetables, drip absorbers for meats and fishes and shellfishes, disposables It is useful also for various uses, such as thermal insulation, a gelling agent for batteries, a water retention agent such as plants and soils, an anti-condensing agent, a water blocking material and a packing material, and artificial snow.
１　生理食塩水
２　含水ゲル粒子
３　円筒
４　底部から６０ｍｌの位置の目盛り線
５　底部から４０ｍｌの位置の目盛り線
６　金網
７　コック
８　円形金網
９　加圧軸
１０　おもり Reference Signs List 1 saline 2 water-containing gel particles 3 cylinder 4 graduation line at a position of 60 ml from the bottom 5 graduation line at a position of 40 ml from the bottom 6 wire mesh 7 cock 8 circular wire mesh 9 pressing shaft 10 weight 10 weight

Claims (12)

  1. 　水溶性ビニルモノマー（ａ１）及び／又は加水分解により水溶性ビニルモノマー（ａ１）となるビニルモノマー（ａ２）、並びに架橋剤（ｂ）を必須構成単位とする架橋重合体（Ａ）と、水不溶性アルミナ含有微粒子（ｃ）及び水溶性アルミニウム塩（ｄ）とを含み、架橋重合体（Ａ）の表面アルミ二ウム被覆率が６０～１００％である吸水性樹脂組成物。 Water-insoluble vinyl monomer (a1) and / or vinyl monomer (a2) that becomes water-soluble vinyl monomer (a1) by hydrolysis, and crosslinked polymer (A) containing a crosslinking agent (b) as an essential constituent unit A water-absorbent resin composition comprising alumina-containing fine particles (c) and a water-soluble aluminum salt (d), and having a surface aluminum coverage of 60 to 100% of the crosslinked polymer (A).
  2. 　水不溶性アルミナ含有微粒子（ｃ）が平均一次粒子径１～１００ｎｍの球状又は不定形の粒子である請求項１記載の吸水性樹脂組成物。 The water-absorbent resin composition according to claim 1, wherein the water-insoluble alumina-containing fine particles (c) are spherical or amorphous particles having an average primary particle diameter of 1 to 100 nm.
  3. 　水不溶性アルミナ含有微粒子（ｃ）がアルミナ変性シリカである請求項１又は２記載の吸水性樹脂組成物。 The water-absorbent resin composition according to claim 1 or 2, wherein the water-insoluble alumina-containing fine particles (c) are alumina-modified silica.
  4. 　水溶性アルミニウム塩（ｄ）が２０℃で１０ｇ／１００ｇＨ２Ｏ以上の水溶解度を持つ結晶性の塩である請求項１～３のいずれか記載の吸水性樹脂組成物。 The water-absorbent resin composition according to any one of claims 1 to 3, wherein the water-soluble aluminum salt (d) is a crystalline salt having a water solubility of 10 g / 100 g H 2 O or more at 20 ° C.
  5. 　水溶性アルミニウム塩（ｄ）が硫酸イオンを有する請求項１～４のいずれか記載の吸水性樹脂組成物。 The water-absorbent resin composition according to any one of claims 1 to 4, wherein the water-soluble aluminum salt (d) has a sulfate ion.
  6. 　架橋重合体（Ａ）の重量に基づいて、水不溶性アルミナ含有微粒子（ｃ）の含有量が０．０１～１重量％、水溶性アルミニウム塩（ｄ）の含有量が０．０５～５重量％である請求項１～５のいずれか記載の吸水性樹脂組成物。 The content of the water-insoluble alumina-containing fine particles (c) is 0.01 to 1% by weight, and the content of the water-soluble aluminum salt (d) is 0.05 to 5% by weight based on the weight of the crosslinked polymer (A) The water-absorbent resin composition according to any one of claims 1 to 5, which is
  7. 　架橋重合体（Ａ）の表面が有機表面架橋剤（ｅ）により架橋された構造を有する請求項１～６のいずれかに記載の吸水性樹脂組成物。 The water-absorbent resin composition according to any one of claims 1 to 6, wherein the surface of the crosslinked polymer (A) has a structure crosslinked by the organic surface crosslinking agent (e).
  8. 　更に炭素数４以下の多価アルコール（ｆ）を含有する請求項１～７のいずれか記載の吸水性樹脂組成物。 The water-absorbent resin composition according to any one of claims 1 to 7, further comprising a polyhydric alcohol (f) having 4 or less carbon atoms.
  9. 　更に疎水性物質（ｇ）を含有する請求項１～８のいずれか記載の吸水性樹脂組成物。 The water-absorbent resin composition according to any one of claims 1 to 8, further comprising a hydrophobic substance (g).
  10. 　水溶性ビニルモノマー（ａ１）及び／又は加水分解により水溶性ビニルモノマー（ａ１）となるビニルモノマー（ａ２）、並びに架橋剤（ｂ）を必須構成単位とする架橋重合体（Ａ）に、水不溶性アルミナ含有微粒子（ｃ）を架橋重合体（Ａ）の重量に基づいて０．０１～１重量％含有する水性コロイド液、及び水溶性アルミニウム塩（ｄ）を架橋重合体（Ａ）の重量に基づいて０．０５～５重量％含有する水溶液、を添加した後、架橋重合体（Ａ）を表面架橋することを特徴とする、架橋重合体（Ａ）の表面アルミ二ウム被覆率が６０～１００％である吸水性樹脂組成物の製造方法。 Water insoluble in a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis and a crosslinked polymer (A) containing a crosslinking agent (b) as an essential constituent unit Aqueous colloidal liquid containing 0.01 to 1% by weight of alumina-containing fine particles (c) based on the weight of the crosslinked polymer (A), and based on the weight of the crosslinked polymer (A) with the water-soluble aluminum salt (d) After adding an aqueous solution containing 0.05 to 5% by weight, the cross-linked polymer (A) is surface-crosslinked, and the surface aluminum coverage of the cross-linked polymer (A) is 60 to 100. % Of the water-absorbent resin composition.
  11. 　架橋重合体（Ａ）に水不溶性アルミナ含有微粒子（ｃ）の水性コロイド液、水溶性アルミニウム塩（ｄ）及び有機表面架橋剤（ｅ）を同時に添加した後、表面架橋する請求項１０記載の製造方法。 The method according to claim 10, wherein an aqueous colloidal solution of water-insoluble alumina-containing fine particles (c), a water-soluble aluminum salt (d) and an organic surface crosslinking agent (e) are simultaneously added to the crosslinked polymer (A) and then surface crosslinked. Method.
  12. 　架橋重合体（Ａ）に水不溶性アルミナ含有微粒子（ｃ）の水性コロイド液、水溶性アルミニウム塩（ｄ）の水溶液、有機表面架橋剤（ｅ）及び炭素数４以下の多価アルコール（ｆ）を同時に添加した後、表面架橋する請求項１０又は１１に記載の製造方法。

          An aqueous colloidal solution of water-insoluble alumina-containing fine particles (c), an aqueous solution of a water-soluble aluminum salt (d), an organic surface crosslinking agent (e) and a polyhydric alcohol having 4 or less carbon atoms (f) The method according to claim 10 or 11, wherein surface crosslinking is carried out after the simultaneous addition.

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