WO2022145274A1 - 農業用保水材およびその製造方法 - Google Patents

農業用保水材およびその製造方法 Download PDF

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Publication number
WO2022145274A1
WO2022145274A1 PCT/JP2021/047069 JP2021047069W WO2022145274A1 WO 2022145274 A1 WO2022145274 A1 WO 2022145274A1 JP 2021047069 W JP2021047069 W JP 2021047069W WO 2022145274 A1 WO2022145274 A1 WO 2022145274A1
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Prior art keywords
water
absorbent resin
retaining material
less
mol
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PCT/JP2021/047069
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English (en)
French (fr)
Japanese (ja)
Inventor
正博 馬場
結稀 藤井
裕典 三枝
利典 加藤
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株式会社クラレ
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Priority claimed from JP2020219318A external-priority patent/JP2024022704A/ja
Priority claimed from JP2020219320A external-priority patent/JP2024022705A/ja
Application filed by 株式会社クラレ filed Critical 株式会社クラレ
Publication of WO2022145274A1 publication Critical patent/WO2022145274A1/ja

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    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G24/00—Growth substrates; Culture media; Apparatus or methods therefor
    • A01G24/30—Growth substrates; Culture media; Apparatus or methods therefor based on or containing synthetic organic compounds
    • A01G24/35—Growth substrates; Culture media; Apparatus or methods therefor based on or containing synthetic organic compounds containing water-absorbing polymers
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G24/00—Growth substrates; Culture media; Apparatus or methods therefor
    • A01G24/40—Growth substrates; Culture media; Apparatus or methods therefor characterised by their structure
    • A01G24/42—Growth substrates; Culture media; Apparatus or methods therefor characterised by their structure of granular or aggregated structure
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G7/00—Botany in general

Definitions

  • the present invention relates to a water-retaining material for agriculture and a method for producing the same.
  • Patent Documents 1 and 2 disclose that a water-absorbent resin containing a polyacrylic acid salt gel as a main component can be used as a water-retaining material for agriculture.
  • Patent Document 3 discloses polyvinyl alcohol-based water-absorbent resin particles having complicated surface shape characteristics.
  • Patent Document 4 discloses an aggregated polyacrylic acid-based water-absorbent resin obtained by a reverse-phase suspension polymerization method, and discloses that this resin has high liquid-permeable performance and can be suitably used for sanitary material applications.
  • Patent Document 5 discloses a polyvinyl alcohol-based water-absorbent resin having specific pores, and discloses that this resin has excellent absorbability of water and liquid fertilizer and can be suitably used for agriculture.
  • Patent Document 6 an example in which a polymer containing an acrylic acid unit as a main component is used as a soil water-retaining material (Patent Document 6), and a polymer containing an acrylic acid unit and / or a sulfonic acid group-containing acrylamide monomer unit as a main component is water-absorbent.
  • An example of using a resin Patent Document 7
  • an example of using a polymer particle of 2-acrylamide-2-methylpropanesulfonic acid as a salt-resistant water-absorbing agent with an average particle size of 50 ⁇ m or less on a volume basis Patent Document 7
  • Document 8 an example of using a polymer particle of 2-acrylamide-2-methylpropanesulfonic acid as a salt-resistant water-absorbing agent with an average particle size of 50 ⁇ m or less on a volume basis
  • the water absorption rate of the water-absorbent resin is very important in addition to the water retention amount of the water-absorbent resin and the water supply to the plant.
  • a seeder is used to sow soil, water, and seeds containing a water-absorbent resin in the seedling raising box that flows by a conveyor. If the water absorption of the soil containing the water-absorbent resin is not completed before sowing the seed paddy, the seed paddy may flow or sink and affect the growth. From the viewpoint of work efficiency, the nursery box flows at a very high speed, so that the water-absorbent resin is required to absorb water at a very high speed.
  • water-absorbent resins for sanitary products have been actively studied, and one of the methods is Various methods have been proposed to prevent the occurrence of "mamako" (a phenomenon in which fine particles associate with each other through water and become lumpy when the water-absorbent resin comes into contact with water), which is one of the causes of the reduction in water absorption rate. ing.
  • Patent Document 9 a method of foaming with a foaming agent at the time of polymerization or crosslinking to knead air bubbles into a gel
  • Patent Document 9 a method of adding a monomer to a fine particle dispersion during turbid polymerization and aggregating the gel
  • Patent Document 10 a method of granulating fine particles with an aqueous solution and drying them
  • the polyacrylic acid-based water-absorbent resin disclosed in Patent Documents 1, 2 and 4 has a significantly reduced water-absorbing performance due to the calcium salt contained in the soil, and thus is agricultural.
  • the amount of water absorption is not sufficient, and it is difficult to develop a stable amount of water absorption for a long period of time.
  • the vinyl alcohol-based water-absorbent resin disclosed in Patent Documents 3 and 5 a further improved water absorption rate may be required.
  • the water-absorbent resins disclosed in Patent Documents 1, 2, 4 and 6 to 10 are used for agriculture, the water-absorbing power may be too strong and the amount of water supplied to plants may not be sufficient.
  • the vinyl alcohol-based water-absorbent resin disclosed in Patent Document 3 may be required to have a further improved water absorption rate.
  • the problem to be solved by the present invention is to solve the above-mentioned problems, that the water absorption rate is excellent, the water absorption amount is sufficiently high even in the presence of a calcium salt, and the water absorption amount does not easily decrease for a long period of time. It is to provide water retention materials for agriculture.
  • the present inventors have repeated detailed studies on agricultural water-retaining materials and have completed the present invention. That is, the present invention includes the following preferred embodiments.
  • An agricultural water-retaining material containing a water-absorbent resin containing a water-absorbent resin.
  • the water-absorbent resin has 0.1 mol% or more and 50 mol% or less of ionic groups with respect to all the constituent units of the water-absorbent resin.
  • Rate of change of D 10 (D 10 of water-retaining material after applying ultrasonic waves) / (D 10 of water-retaining material before applying ultrasonic waves) Is 1 or less, water retention material.
  • Water retention material [6]
  • the water-absorbent resin comprises one or more selected from the group consisting of a vinyl alcohol-based polymer, an acrylic acid-based polymer, an acrylamide-based polymer, and a methacrylic acid-based polymer.
  • the process includes a coagulation step of agglomerating the water-absorbent resin existing as primary particles by contacting them in a swollen state, and a drying step of drying the agglomerated water-absorbent resin under a pressure of 0.2 MPa or less.
  • the method for producing a water-retaining material according to any one of [1] to [10].
  • an agricultural water-retaining material having an excellent water absorption rate, a sufficiently high water absorption amount even in the presence of a calcium salt, and the water absorption amount does not easily decrease for a long period of time.
  • the agricultural water-retaining material of the present invention contains a water-absorbent resin.
  • the present invention is characterized in that the water-absorbent resin has an ionic group of 0.1 mol% or more and 50 mol% or less with respect to all the constituent units of the water-absorbent resin.
  • the rate of change of the volume-based 10% particle diameter D 10 of the water-retaining material before and after applying ultrasonic waves in the water-retaining material swelling test Is also characterized by being 1 or less.
  • the volume-based 10% particle diameter means a particle diameter in which the ratio of particles smaller than this is 10% on a volume basis.
  • a D 10 change rate of 1 or less can be achieved, for example, by the presence of the water-absorbent resin as an agglomerate in the water-retaining material.
  • the water-absorbent resin in the water-retaining material, exists as an agglomerate of particles, preferably as an agglomerate of primary particles.
  • primary particles mean particles that are not agglomerated.
  • the present inventors show that the water-retaining material has the above-mentioned characteristics, so that the water-retaining material exhibits an excellent water absorption rate and a sufficiently high water absorption amount even in the presence of a calcium salt.
  • a calcium salt was found to be difficult to decrease over a long period of time.
  • the reason is not clear, but the following reasons are presumed as a non-limiting mechanism of action. Since the water-retaining material of the present invention contains a water-absorbent resin, it swells when it absorbs water. On the other hand, since the cohesive force of the water-absorbent resin in the water-retaining material is moderately weak, the water-retaining material disintegrates with expansion.
  • the surface area of the water-absorbent resin that comes into contact with water increases, so it is presumed that the water absorption rate increases. Further, the water-absorbent resin surface is in contact with water because the water-absorbent resin has an ionic group content that is not too high, that is, an ionic group content of 50 mol% or less with respect to all the constituent units of the water-absorbent resin. Not only does it absorb water rapidly, but water can also enter the voids of the water-absorbent resin inside the water-retaining material well, and as a result, the surface area of the water-absorbent resin expanded due to the collapse of the water-retaining material is brought into contact with water.
  • the water absorption rate will be significantly faster because it can be used more effectively. Furthermore, since the water-absorbent resin has the above-mentioned specific ionic group content, ionic cross-linking due to the calcium salt and the ionic group is unlikely to occur, so that the water absorption of the water-retaining material is sufficient even in the presence of the calcium salt. It is presumed that the amount of water absorption is high and the amount of water absorption is unlikely to decrease over a long period of time.
  • the state of the water-retaining material at the initial stage of water absorption is reproduced by dispersing the water-retaining material in a medium in which the water-retaining material does not absorb much liquid, instead of a medium (for example, water) that is quickly absorbed by the water-retaining material.
  • a medium for example, water
  • a 20% by mass sodium chloride aqueous solution is used as such a medium that is not so absorbed.
  • the water-retaining material can be made to absorb the liquid, whereby the state of swelling and disintegration of the water-retaining material can be reproduced.
  • the water retention material swelling test can be carried out by the following procedure.
  • the water-retaining material as a sample is dispersed in a dispersion medium, and for example, using a laser diffraction / scattering type particle size distribution measuring device, a volume-based 10% particle size D 10 (D 10 of the water-retaining material before applying ultrasonic waves). Equivalent to).
  • the water-retaining material is swelled by absorbing the dispersion medium into the water-retaining material by ultrasonic irradiation for 5 minutes, and then the volume-based 10% particle diameter D 10 of the water-retaining material (of the water-retaining material after applying ultrasonic waves). (Equivalent to D10 ) is measured. The measurement conditions are shown below.
  • the present inventors have found that among the water-absorbent resin particles forming the water-retaining material, particles having a relatively small particle size are one of the factors that determine the water absorption rate of the entire water-retaining material. Therefore, in the present invention, D 10 is used as a constituent requirement for achieving an excellent water absorption rate.
  • the rate of change of the volume-based 10% particle diameter D 10 of the water-retaining material before and after applying ultrasonic waves is 1 or less. If the rate of change of D 10 is greater than 1, it is difficult to obtain the desired water absorption rate.
  • the rate of change of D 10 is preferably 0.95 or less, more preferably 0.94 or less, more preferably 0.93 or less, more preferably 0.92 or less, more preferably 0.91 or less, still more preferably 0. It is .90 or less, more preferably 0.85 or less, particularly preferably 0.80 or less, and particularly more preferably 0.75 or less.
  • the lower limit of the rate of change of D 10 is not particularly limited.
  • the rate of change of D 10 is, for example, 0.30 or more.
  • the rate of change of D 10 is, for example, the presence of the water-absorbent resin as an aggregate in the water-retaining material, the adjustment of the binder amount, pressure, temperature or the amount of the plasticizer in the step of aggregating the water-absorbent resin, and the aggregated water-absorbent resin.
  • the pressure, temperature or amount of plasticizer in the drying step or by adjusting the particle size or shape of the water-absorbent resin particles before aggregation, it can be adjusted to the lower limit value or more and the upper limit value or less.
  • the maximum particle size on the smallest particle size side in the state after applying ultrasonic waves is preferably 1 ⁇ m or more, more preferably 5 ⁇ m or more, still more preferably 10 ⁇ m or more, and particularly preferably 30 ⁇ m or more. It is preferably 1000 ⁇ m or less, more preferably 500 ⁇ m or less, still more preferably 200 ⁇ m or less, and particularly preferably 100 ⁇ m or less.
  • the maximum particle size is 0.011 ⁇ m, 0.013 ⁇ m, 0.015 ⁇ m, 0.017 ⁇ m, 0.02 ⁇ m, 0.023 ⁇ m, 0.026 ⁇ m, 0.03 ⁇ m, 0.034 ⁇ m, 0.039 ⁇ m, 0.044 ⁇ m, 0.051 ⁇ m, 0.058 ⁇ m, 0.067 ⁇ m, 0.076 ⁇ m, 0.087 ⁇ m, 0.1 ⁇ m, 0.115 ⁇ m, 0.131 ⁇ m, 0.15 ⁇ m, 0.172 ⁇ m, 0.197 ⁇ m, 0.226 ⁇ m, 0.
  • the maximum particle size is at least the lower limit value and at least the upper limit value, a more preferable water absorption rate can be easily obtained.
  • the maximum particle size can be adjusted to be equal to or higher than the lower limit value and lower than the upper limit value by adjusting the particle size of the water-absorbent resin particles before aggregation, for example.
  • the water-absorbent resin contained in the water-retaining material exists as an aggregate of primary particles.
  • the average particle size of the primary particles of the water-absorbent resin contained in the water-retaining material is preferably 1 ⁇ m or more, more preferably 10 ⁇ m or more, still more preferably 30 ⁇ m or more, particularly preferably 50 ⁇ m or more, preferably 2000 ⁇ m or less, more preferably 2000 ⁇ m or less. It is 1000 ⁇ m or less, more preferably 700 ⁇ m or less, and particularly preferably 150 ⁇ m or less.
  • the average particle diameter of the primary particles is at least the lower limit value and at least the upper limit value, a more preferable water absorption rate can be easily obtained.
  • the average particle diameter of the primary particles is at least the above lower limit value, it is easy to suppress the generation of dust during the production of the water retention material.
  • the average particle size of the primary particles can be measured, for example, using an electron microscope or a sieve with a specific opening.
  • the water-absorbent resin contained in the water-retaining material is 0.1 mol% or more, preferably 0.5 mol% or more, more preferably 1.0 mol% or more, still more preferably 2 with respect to all the constituent units of the water-absorbent resin. It has an ionic group of 0.0 mol% or more, particularly preferably 3.0 mol% or more.
  • the "constituent unit” means a repeating unit that constitutes the water-absorbent resin. When the ionic group content is at least the above lower limit value, the water-absorbent resin tends to have a higher water absorption amount or water absorption rate.
  • the water-absorbent resin is 50 mol% or less, preferably 40 mol% or less, more preferably 30 mol% or less, still more preferably 20 mol% or less, and particularly preferably 10 mol% or less, based on all the constituent units of the water-absorbent resin.
  • the ionic group content is not more than the above upper limit value, the water-absorbent resin tends to maintain an excellent liquid absorption amount or liquid absorption rate even in the presence of divalent ions (for example, calcium ions) contained in the soil. This liquid absorption amount or liquid absorption rate is unlikely to decrease over a long period of time, and decomposition of the water-absorbent resin by ultraviolet rays is unlikely to occur.
  • the content of ionic groups in the water-absorbent resin and the content of various structural units described later are, for example, solid 13 C-NMR (nuclear magnetic resonance spectroscopy), FTIR (Fourier transform infrared spectroscopy) or acid base. It can be measured by titration or the like. Further, the content of the ionic group in the water-absorbent resin and the content of various structural units described later are, for example, the compounding ratio of the monomer that brings about the ionic group and the monomer that forms various structural units, and those at the time of reaction. It can be adjusted by adjusting the consumption rate or reactivity ratio, reaction temperature, solvent and the like.
  • the ionic group may exist as an ionic group or a derivative thereof.
  • the ionic group is preferably a carboxyl group, a sulfonic acid group, an ammonium group or a salt thereof, more preferably a carboxyl group, an ammonium group or a salt thereof, and particularly preferably a carboxyl group or a salt thereof. Therefore, in a preferred embodiment of the present invention, the water-absorbent resin has one or more selected from the group consisting of a carboxyl group, a sulfonic acid group and an ammonium group as an ionic group.
  • the above-mentioned ionic group content is the content of the ionic group and its derivative or The content of the derivative of the ionic group.
  • the water retention material preferably has a water content of 11% by mass or more and 50% by mass or less and a bulk density of 0.20 g / mL or more and 1.25 g / mL or less.
  • the water content of the water-retaining material of the present invention is preferably 11% by mass or more, more preferably 15% by mass or more, more preferably 16% by mass or more, still more preferably 20% by mass or more.
  • the water content of the water-retaining material of the present invention is preferably 50% by mass or less, more preferably 40% by mass or less, more preferably 33% by mass or less, still more preferably 30% by mass or less.
  • the water-absorbent resins contained in the water-retaining material are less likely to stick to each other, are less likely to form a lump, and are likely to secure a sufficient contact area with water, so that a desired water absorption rate can be easily obtained. ..
  • the water content of the water-retaining material is, for example, the type and content of the ionic group of the water-absorbent resin contained in the water-retaining material; the drying conditions at the time of manufacturing the water-absorbent resin contained in the water-retaining material; the storage conditions of the water-retaining material, etc. as appropriate. By adjusting, it can be adjusted within the above range.
  • the water content can be measured using a halogen moisture meter, for example, by the method described in Examples described later.
  • the bulk density of the water-retaining material of the present invention is preferably 0.20 g / mL or more, more preferably 0.30 g / mL or more, and further preferably 0.35 g / mL or more.
  • the bulk density of the water-retaining material is at least the above lower limit value, the water-retaining material is less likely to float on water, and it is easy to secure a sufficient contact area with water, so that a desired water absorption rate can be easily obtained.
  • dust is less likely to be generated, so that the handleability tends to be excellent.
  • the bulk density of the water-retaining material of the present invention is preferably 1.25 g / mL or less, more preferably 0.95 g / mL or less, still more preferably 0.70 g / mL or less.
  • the bulk density of the water-retaining material is not more than the upper limit, it is difficult for the water-retaining material to be densely filled, and it is easy to secure sufficient water permeability, so that a desired water absorption rate can be easily obtained. Further, when the bulk density of the water-retaining material is not more than the upper limit value, this occurrence is unlikely to occur as it is when mixed with water.
  • the bulk density of the water-retaining material is, for example, the particle size and shape of the water-absorbent resin contained in the water-retaining material; the water content of the water-retaining material; It can be adjusted within the above range by appropriately adjusting the type and amount of the above, pressure, etc.).
  • the bulk density can be measured, for example, by the method described in Examples described later.
  • the water-absorbent resin contained in the water-retaining material has an ionicity of 0.1 mol% or more and 50 mol% or less with respect to all the constituent units of the water-absorbent resin.
  • the water content of the agricultural water-retaining material having a group is preferably 11% by mass or more, preferably 50% by mass or less, and the bulk density is preferably 0.20 g / mL or more, preferably 1.25 g / mL or less. It was found that the water-retaining material showed a better water absorption rate.
  • the water-absorbent resin absorbs water by having an ionic group content that is not too high, that is, an ionic group content of 50 mol% or less with respect to all the constituent units of the water-absorbent resin.
  • the elastic modulus of the water-retaining material is high, it is considered that the water-retaining material is less likely to cause gel blocking, and the water absorption rate is increased by ensuring the water permeability.
  • having an appropriate water content improves the mobility of the polymer chains of the water-absorbent resin in the water-retaining material, thereby suppressing the decrease in water permeability between the water-absorbent resins and increasing the water absorption rate. ..
  • the water-retaining material can efficiently absorb water by ensuring the water permeability between the resins in the water-retaining material by having an appropriate bulk density.
  • the water-retaining material before being used as an agricultural water-retaining material that is, at the time of storage (for example, in a storage container) and immediately before being used in combination with a medium or the like described later, satisfies the above water content and bulk density. Is preferable.
  • the water retention material preferably passes through a sieve with a nominal opening of 3000 ⁇ m, more preferably passes through a sieve with a nominal opening of 2000 ⁇ m, more preferably passes through a sieve with a nominal opening of 1500 ⁇ m, and particularly preferably passes through a sieve with a nominal opening of 1000 ⁇ m. It has a particle size that passes through a sieve, preferably does not pass through a sieve with a nominal opening of 10 ⁇ m, more preferably does not pass through a sieve with a nominal opening of 50 ⁇ m, and more preferably does not pass through a sieve with a nominal opening of 100 ⁇ m, particularly preferably.
  • the water retention material has a particle size that does not pass through a sieve with a nominal opening of 200 ⁇ m.
  • the water retention material has a particle size that passes through a sieve with a nominal opening of 3000 ⁇ m and does not pass through a sieve with a nominal opening of 10 ⁇ m.
  • the water-retaining material has such a particle size, it is easy to obtain better handleability and better water absorption rate.
  • the water-absorbent resin preferably has a crosslinked structure from the viewpoint of suppressing elution of the water-absorbent resin due to irrigation.
  • the water-absorbent resin When the water-absorbent resin has a crosslinked structure, the water-absorbent resin becomes a gel state at the time of water absorption.
  • the form of the crosslinked structure is not particularly limited, and examples thereof include a crosslinked structure formed by an ester bond, an ether bond, an acetal bond, a carbon-carbon bond, and the like.
  • the water-absorbent resin contained in the water-retaining material is not particularly limited. From the viewpoint of ease of production and water retention, the water-absorbent resin is preferably one or more selected from the group consisting of vinyl alcohol-based polymers, acrylic acid-based polymers, acrylamide-based polymers and methacrylic acid-based polymers. It contains, more preferably one or more selected from the group consisting of vinyl alcohol-based polymers and acrylamide-based polymers, and more preferably composed of vinyl alcohol-based polymers or acrylamide-based polymers.
  • the vinyl alcohol-based polymer means a polymer having the highest content of a structural unit derived from vinyl alcohol (hereinafter referred to as “vinyl alcohol unit”) among all the structural units. This also applies to acrylic acid-based polymers, acrylamide-based polymers and methacrylic acid-based polymers.
  • vinyl alcohol-based polymer As an example of the vinyl alcohol-based polymer [hereinafter, may be referred to as vinyl alcohol-based polymer (A)], polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, and their vinyl alcohol units are acetalized by an acetal agent. It can be mentioned as a polymer.
  • the content of the vinyl alcohol polymer (A) in the water-absorbent resin is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. , 100% by mass.
  • the vinyl alcohol-based polymer (A) comprises a copolymer of a vinyl alcohol unit and a monomer constituent unit having an ionic group or a derivative thereof.
  • the ionic group or a derivative thereof contained in the vinyl alcoholic polymer (A) is preferably a carboxyl group, a sulfonic acid group, an ammonium group, or a salt thereof, and more preferably a carboxyl group, an ammonium group, or a salt thereof. And particularly preferably a carboxyl group or a salt thereof.
  • the content of the copolymer in the vinyl alcohol-based polymer (A) is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more. Yes, especially preferably 100% by mass.
  • the vinyl alcohol-based polymer (A) When the vinyl alcohol-based polymer (A) has a carboxyl group, a sulfonic acid group and an ammonium group as ionic groups, the vinyl alcohol-based polymer (A) may be, for example, (i-1) a carboxyl group or a sulfonic acid group. And a saponified product of a polymer of one or more selected from the group consisting of a monomer having an ammonium group and a derivative of the monomer and a vinyl ester; and the like.
  • the monomer having a carboxyl group is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, maleic acid, and itaconic acid.
  • examples of the derivative of the monomer having a carboxyl group include anhydrate, an esterified product, and a neutralized product of the monomer, and examples thereof include methyl acrylate, methyl methacrylate, monomethyl maleate, and itaconic acid. Dimethyl acid, maleic anhydride and the like can be used. Therefore, in one embodiment of the present invention, the vinyl alcohol-based polymer (A) contains one or more monomer constituent units selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid and derivatives thereof. include.
  • the monomer having a sulfonic acid group is not particularly limited, and examples thereof include vinyl sulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, p-styrenesulfonic acid and the like. be able to.
  • examples of the derivative of the monomer having a sulfonic acid group include an esterified product of the monomer and a neutralized product, and examples thereof include sodium vinyl sulfonate and 2-acrylamide-2-methylpropane sulfonic acid. Sodium, sodium p-styrene sulfonate and the like can be used.
  • the monomer having an ammonium group is not particularly limited, and examples thereof include diallyldimethylammonium chloride, vinyltrimethylammonium chloride, allyltrimethylammonium chloride, p-vinylbenzyltrimethylammonium chloride, and 3. -(Methalamide) propyltrimethylammonium chloride and the like can be mentioned.
  • Examples of the derivative of the monomer having an ammonium group include amines of the monomers, and examples thereof include diallylmethylamine, vinylamine, allylamine, p-vinylbenzyldimethylamine, and 3- (methacrylamide). Propyldimethylamine and the like can be used.
  • the vinyl ester is not particularly limited, and examples thereof include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl stearate, vinyl benzoate, vinyl trifluoroacetate, and vinyl acetate.
  • vinyl acetate and the like can be mentioned, and vinyl acetate is preferable.
  • the saponified product of (i-1) is, for example, a known polymerization of one or more selected from the group consisting of a monomer having a carboxyl group and a derivative of the monomer and a vinyl ester using a known polymerization initiator. It can be produced by carrying out a reaction and then carrying out a saponification reaction by a known method.
  • a part or all of the ionic group (for example, carboxyl group) contained in the vinyl alcohol polymer (A) is in the form of a salt (carboxylate when the ionic group is a carboxyl group). May be.
  • salt counter cations are alkali metal ions such as lithium ion, sodium ion, potassium ion, rubidium ion, and cesium ion; alkaline earth metal ions such as magnesium ion, calcium ion, strontium ion, and barium ion; Examples thereof include aluminum ions and other metal ions such as zinc ions; onium cations such as ammonium ions, imidazoliums, pyridiniums, and phosphonium ions; and the like.
  • potassium ion, ammonium ion, calcium ion, and magnesium ion are preferable from the viewpoint of easily obtaining a more preferable water absorption amount or water absorption rate.
  • Potassium ions and ammonium ions are more preferable from the viewpoint of plant growth, and calcium ions are more preferable from the viewpoint of easily maintaining the amount of liquid absorbed or the rate of liquid absorption even when in contact with divalent ions contained in the soil.
  • the above (i-1) has a carboxyl group.
  • a method (I) using a neutralized product of a monomer; a method (III) of producing a vinyl alcohol-based polymer (A) having a carboxyl group and then neutralizing the polymer (A) in the above (i-1) can be mentioned. Above all, the above method (III) is preferable.
  • the content of the ionic group in the vinyl alcohol-based polymer (A) is 0.1 mol% or more, preferably 1 mol% or more, more preferably 1 mol% or more, based on all the constituent units of the vinyl alcohol-based polymer (A). 3 mol% or more, more preferably 4 mol% or more, particularly preferably 5 mol% or more, 50 mol% or less, preferably 40 mol% or less, more preferably 30 mol% or less, still more preferably 25 mol% or less. It is even more preferably 20 mol% or less, particularly preferably 15 mol% or less, and even more preferably 10 mol% or less.
  • the vinyl alcohol-based polymer (A) tends to have a higher water absorption amount or water absorption rate.
  • the vinyl alcohol-based polymer (A) maintains an excellent liquid absorption amount or liquid absorption rate even when in contact with divalent ions contained in the soil. The liquid absorption amount or the liquid absorption rate is unlikely to decrease over a long period of time, and the vinyl alcohol-based polymer (A) is less likely to be decomposed by ultraviolet rays.
  • the amount of the carboxyl group derived from acrylic acid or a salt thereof among the above-mentioned carboxyl groups is the total constituent unit of the vinyl alcohol-based polymer. On the other hand, it is preferably 20 mol% or less, more preferably 15 mol% or less, particularly preferably 10 mol% or less, and may be 0 mol%.
  • the amount of the carboxyl group derived from acrylic acid or a salt thereof among the above-mentioned carboxyl groups is not more than the upper limit value, more excellent weather resistance (particularly ultraviolet resistance) can be easily obtained.
  • the ionic groups contained in the vinyl alcohol polymer (A) are in the form of derivatives, and in a more preferred embodiment, the ionicity contained in the vinyl alcohol polymer (A). Most of the groups are in the form of derivatives, and in one particularly preferred embodiment, all of the ionic groups contained in the vinyl alcohol polymer (A) are in the form of derivatives.
  • the "constituent unit” means a repeating unit constituting the polymer.
  • the vinyl alcohol unit is "1 unit” and two vinyl alcohol units are acetalized. The structure is counted as "2 units”.
  • the content of the vinyl alcohol unit of the vinyl alcohol-based polymer (A) is preferably more than 20 mol%, more preferably 50 mol% or more, still more preferably 50 mol% or more, based on all the constituent units of the vinyl alcohol-based polymer (A). Is 60 mol% or more, preferably 98 mol% or less, more preferably 95 mol% or less, still more preferably 90 mol% or less.
  • the content of the vinyl alcohol unit can be measured by FTIR, solid 13 C-NMR, or the like as described above, but it can also be calculated from the consumption of acetic anhydride when reacted with a certain amount of acetic anhydride.
  • the vinyl alcohol-based polymer (A) contains other structural units other than the vinyl alcohol unit.
  • examples of the above other structural units include vinyl acetate and structural units derived from vinyl carboxylate such as vinyl pivalate; structural units derived from olefins such as ethylene, 1-butene, and isobutylene; acrylic acid and its derivatives, methacrylic acid. Examples thereof include acid and its derivatives, acrylamide and its derivatives, methacrylic acid and its derivatives, maleic acid and its derivatives, and structural units derived from maleimide derivatives and the like.
  • the other constituent units may contain one type or a plurality of types.
  • the content of the other structural units is preferably 50 mol% or less, more preferably 30 mol% or less, still more preferably 20 mol% or less, and further, with respect to all the structural units of the vinyl alcohol-based polymer (A). More preferably 10 mol% or less, particularly preferably 5 mol% or less, preferably 0.1 mol% or more, more preferably 0.5 mol% or more, still more preferably 1 mol% or more, still more preferably 2 It is mol% or more, particularly preferably 3 mol% or more.
  • the content of the other structural units is at least the lower limit value and at least the upper limit value, it is easy to obtain a better water absorption amount or water absorption rate of the water retention material of the present invention.
  • the viscosity average degree of polymerization of the vinyl alcohol polymer (A) is not particularly limited, but is preferably 20000 or less, more preferably 10000 or less, still more preferably 4000 or less, and particularly preferably 3000 or less from the viewpoint of ease of production. be.
  • the viscosity average degree of polymerization is preferably 100 or more, more preferably 200 or more, still more preferably 400 or more.
  • the viscosity average degree of polymerization of the vinyl alcohol polymer (A) can be measured by a method based on JIS K 6726.
  • the measurement of the viscosity average degree of polymerization is carried out. It can be done after cutting the structure.
  • the cutting can be performed by a general method (for example, hydrolysis using an acid or an alkali).
  • the vinyl alcohol-based polymer (A) preferably contains a crosslinked structure from the viewpoint of suppressing elution of the vinyl alcohol-based polymer due to irrigation.
  • the form of the crosslinked structure is not particularly limited, and examples thereof include a crosslinked structure formed by an ester bond, an ether bond, an acetal bond, a carbon-carbon bond, and the like.
  • the presence or absence of the crosslinked structure in the vinyl alcohol polymer (A) can be examined, for example, by the elution rate in hot water or dimethyl sulfoxide at 100 ° C.
  • the elution rate represented by the ratio of the mass of the eluted sample to the mass of the sample is a certain value or less (for example, 90% by mass or less). With the presence, the existence of the crosslinked structure can be confirmed.
  • ester bond when the vinyl alcohol polymer (A) has a carboxyl group as an ionic group, an ester formed between the hydroxyl group and the carboxyl group of the vinyl alcohol polymer (A). Bonding can be mentioned.
  • the ether bond include an ether bond formed by dehydration condensation between the hydroxyl groups of the vinyl alcohol polymer (A).
  • Another example of the ether bond is an ether bond formed when a polyvalent epoxy compound having a plurality of epoxy groups in one molecule is used in the production of the vinyl alcohol polymer (A). can.
  • the acetal bond when an aldehyde having a carboxyl group is used in the production of the vinyl alcohol polymer (A), the hydroxyl groups of the two vinyl alcohol polymers (A) are acetalized with the aldehyde.
  • the acetal bond formed by the reaction can be mentioned.
  • Another example of the acetal bond is an acetal bond formed when a polyvalent aldehyde compound having a plurality of aldehyde groups in one molecule is used in the production of the vinyl alcohol polymer (A). can.
  • the carbon-carbon bond is, for example, carbon-carbon formed by coupling between carbon radicals of the vinyl alcohol-based polymer (A), which is generated when the vinyl alcohol-based polymer (A) is irradiated with an active energy ray. Bonding can be mentioned.
  • These crosslinked structures may contain one type or a plurality of types. Of these, a crosslinked structure with an ester bond or an acetal bond is preferable from the viewpoint of ease of production, and a crosslinked structure with an acetal bond is more preferable from the viewpoint of maintaining water retention during seedling raising and UV resistance.
  • Such a crosslinked structure may be formed at the same time as the acetalization reaction in the step of acetalizing at least a part of the vinyl alcohol units by, for example, one or more selected from the polyvalent aldehyde compound, or may be formed at the same time as the acetalization reaction step.
  • the cross-linking agent may be further added before the coagulation step described later to be formed before the coagulation step, or the cross-linking agent may be further added in the coagulation step at the same time as the coagulation step. It may be formed or may be formed after the aggregation step by further adding a cross-linking agent after the aggregation step. In the present invention, it is preferable to form a crosslinked structure by further adding a crosslinking agent.
  • Examples of the cross-linking agent include a polyvalent epoxy compound and a polyvalent aldehyde compound, and among them, a polyvalent aldehyde compound is preferable.
  • Examples of the polyvalent epoxy compound include bifunctional epoxy compounds such as ethylene glycol diglycidyl ether.
  • Examples of the polyhydric aldehyde compound include glyoxal, malonaldehyde, succinaldehyde, glutaaldehyde, 1,9-nonandial, adipaldehyde, malealdehyde, tartaraldehyde, citraldehyde, phthalaldehyde, isophthalaldehyde, and terephthalaldehyde.
  • Bifunctional aldehydes can be mentioned.
  • a polyvalent aldehyde compound When a polyvalent aldehyde compound is used as a cross-linking agent, the hydroxyl group of one of the two vinyl alcoholic polymers (A) undergoes an acetalization reaction with one aldehyde group of the polyvalent aldehyde compound, and also Two acetal bonds can be introduced by the hydroxyl group of the other of the two vinyl alcohol-based polymers (A) undergoing an acetalization reaction with another aldehyde group of the polyvalent aldehyde compound. ..
  • the amount of the cross-linking agent in the vinyl alcohol-based polymer (A) is preferably 0.001 mol% or more, more preferably 0, from the viewpoint of easily maintaining water retention in the soil. It is 005 mol% or more, more preferably 0.01 mol% or more, still more preferably 0.03 mol% or more, preferably 0.5 mol% or less, more preferably 0.4 mol% or less, still more preferably. It is 0.3 mol% or less.
  • acrylic acid-based polymer which may contain the water-absorbent resin in the present invention
  • the structural unit derived from acrylic acid or an acrylic acid derivative (hereinafter referred to as “acrylic acid-derived structural unit”) is the most among all the structural units. Contains in high content.
  • raw materials for acrylic acid-based polymers include acrylic acid, sodium acrylate, potassium acrylate, calcium acrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec acrylate.
  • acrylic acid-based polymers include those obtained by copolymerizing one or more of these monomers with at least one other monomer copolymerizable by a known method.
  • examples of other monomers capable of copolymerization include monomers that bring about other structural units other than acrylic acid-derived structural units, which will be described later.
  • the content of the acrylic acid-based polymer in the water-absorbent resin is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, and 100% by mass. May be.
  • a part or all of the ionic group (for example, carboxyl group) contained in the acrylic acid-based polymer is in the form of a salt (carboxylate when the ionic group is a carboxyl group). May be good.
  • salt counter cations are alkali metal ions such as lithium ion, sodium ion, potassium ion, rubidium ion, and cesium ion; alkaline earth metal ions such as magnesium ion, calcium ion, strontium ion, and barium ion; Examples thereof include aluminum ions and other metal ions such as zinc ions; onium cations such as ammonium ions, imidazoliums, pyridiniums, and phosphonium ions; and the like.
  • potassium ion, ammonium ion, calcium ion, and magnesium ion are preferable from the viewpoint of easily obtaining a more preferable water absorption amount or water absorption rate.
  • Potassium ions and ammonium ions are more preferable from the viewpoint of plant growth, and calcium ions are more preferable from the viewpoint of easily maintaining the amount of liquid absorbed or the rate of liquid absorption even when in contact with divalent ions contained in the soil.
  • the content of the ionic group in the acrylic acid-based polymer is 0.1 mol% or more, preferably 1 mol% or more, more preferably 3 mol% or more, and further, with respect to all the constituent units of the acrylic acid-based polymer. It is preferably 4 mol% or more, particularly preferably 5 mol% or more, 50 mol% or less, preferably 40 mol% or less, more preferably 30 mol% or less, still more preferably 25 mol% or less, still more preferably 20. It is mol% or less, particularly preferably 15 mol% or less, and even more preferably 10 mol% or less.
  • the acrylic acid-based polymer tends to have a higher water absorption amount or water absorption rate.
  • the acrylic acid-based polymer can easily maintain an excellent liquid absorption amount or liquid absorption rate even when in contact with divalent ions contained in the soil. This liquid absorption amount or liquid absorption rate is unlikely to decrease over a long period of time, and decomposition of the acrylic acid-based polymer by ultraviolet rays is unlikely to occur.
  • the amount of the carboxyl group derived from acrylic acid or a salt thereof among the above-mentioned carboxyl groups is based on all the constituent units of the acrylic acid-based polymer. It is preferably 20 mol% or less, more preferably 15 mol% or less, particularly preferably 10 mol% or less, and may be 0 mol%.
  • the amount of the carboxyl group derived from acrylic acid or a salt thereof among the above-mentioned carboxyl groups is not more than the upper limit value, more excellent weather resistance (particularly ultraviolet resistance) can be easily obtained.
  • more than half of the ionic groups contained in the acrylic acid polymer are in the form of derivatives, and in a more preferred embodiment, most of the ionic groups contained in the acrylic acid polymer are derivatives. It is a form, and in a particularly preferable embodiment, all of the ionic groups contained in the acrylic acid-based polymer are in the form of a derivative.
  • the content of the acrylic acid-derived structural unit of the acrylic acid-based polymer is preferably more than 20 mol%, more preferably 50 mol% or more, still more preferably 60 mol% with respect to all the structural units of the acrylic acid-based polymer.
  • the above is preferably 98 mol% or less, more preferably 95 mol% or less, still more preferably 90 mol% or less.
  • the acrylic acid-based polymer contains other structural units other than the acrylic acid-derived structural unit.
  • Examples of the above other building blocks include vinyl alcohol units; building blocks derived from vinyl carboxylates such as vinyl acetate and vinyl pivalate; building blocks derived from olefins such as ethylene, 1-butene, and isobutylene; methacrylic acid and Derivatives thereof, acrylamide and its derivatives, methacrylic acid and its derivatives, maleic acid and its derivatives, structural units derived from maleimide derivatives and the like; and the like can be mentioned.
  • the other constituent units may contain one type or a plurality of types.
  • the content of the other structural units is preferably 50 mol% or less, more preferably 30 mol% or less, still more preferably 20 mol% or less, still more preferably 20 mol% or less, based on all the structural units of the acrylic acid-based polymer. 10 mol% or less, particularly preferably 5 mol% or less, preferably 0.1 mol% or more, more preferably 0.5 mol% or more, still more preferably 1 mol% or more, still more preferably 2 mol% or more. , Particularly preferably 3 mol% or more.
  • the content of the other structural units is at least the lower limit value and at least the upper limit value, it is easy to obtain a better water absorption amount or water absorption rate of the water retention material of the present invention.
  • the weight average molecular weight of the acrylic acid-based polymer is not particularly limited, but from the viewpoint of ease of production, it is preferably 1,000,000 or less, more preferably 5,000,000 or less, still more preferably 3,000,000 or less. Below, it is particularly preferably 1,000,000 or less. On the other hand, from the viewpoint of the mechanical properties of the acrylic acid-based polymer and the elution resistance to water, the weight average molecular weight is preferably 1000 or more, more preferably 5000 or more, still more preferably 10,000 or more.
  • the weight average molecular weight of the acrylic acid-based polymer can be measured by, for example, GPC.
  • the weight average molecular weight should be measured after cutting the crosslinked structure. Can be done.
  • the cutting can be performed by a general method (for example, hydrolysis using an acid or an alkali).
  • the acrylic acid-based polymer preferably contains a crosslinked structure from the viewpoint of suppressing elution of the acrylic acid-based polymer due to irrigation.
  • the form of the cross-linked structure is not particularly limited, and examples thereof include a cross-linked structure using a general cross-linking agent.
  • the presence or absence of the crosslinked structure in the acrylic acid-based polymer can be examined by, for example, the elution rate in hot water or dimethyl sulfoxide at 100 ° C.
  • the crosslinked structure may be formed at the same time as the copolymerization reaction in the copolymerization step of, for example, the monomer which brings about the structural unit derived from acrylic acid and the monomer which brings about the structural unit other than the structural unit derived from acrylic acid, or the copolymerization reaction. It may be formed before the aggregation step by further adding a cross-linking agent before the aggregation step described later in another step other than the step, or it may be formed by further adding the cross-linking agent in the aggregation step. It may be formed at the same time, or may be formed after the aggregation step by further adding a cross-linking agent after the aggregation step. In the present invention, it is preferable to form a crosslinked structure by further adding a crosslinking agent.
  • cross-linking agents examples include N, N'-methylenebisacrylamide, divinylbenzene, ethylene glycol diglycidyl ether, pentaerythritol triallyl ether, pentaerythritol triacrylate, pentaerythritol tetraacrylate, 1,6-hexanediol diacrylate, 1,9-Nonandiol diacrylate, 1,10-decanediol diacrylate, neopentyl glycol diacrylate, 2-hydroxy-3-methacrylicpropyl acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, trimethyl propanetriacrylate and Tris- (2-acryloxyethyl) isocyanurate and the like can be mentioned.
  • the amount of the cross-linking agent in the acrylic acid-based polymer is preferably 0.001 mol% or more, more preferably 0.01 mol%, from the viewpoint of easily maintaining water retention in the soil.
  • the above is more preferably 1.0 mol% or more, still more preferably 2.0 mol% or more, preferably 10 mol% or less, more preferably 5 mol% or less, still more preferably 3 mol% or less.
  • acrylic acid-based polymer examples include a crosslinked product of an acrylic acid-sodium acrylate copolymer.
  • Commercially available products include highly absorbent polymers (acrylic acid salt type, manufactured by Wako Pure Chemical Industries, Ltd.), Acrihope (registered trademark) (manufactured by Nippon Shokubai Co., Ltd.), and Sunwet (registered trademark) (Sanyo Chemical Industries, Ltd.). Made) and the like.
  • the acrylamide-based polymer that may be contained in the water-absorbent resin in the present invention contains a structural unit derived from acrylamide or an acrylamide derivative (hereinafter referred to as "acrylamide-derived structural unit") at the highest content among all the structural units.
  • acrylamide-derived structural unit a structural unit derived from acrylamide or an acrylamide derivative
  • examples of raw materials for acrylamide-based polymers include acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, N-alkylacrylamide, and trimethyl [3- (acryloylamino) propyl] aminium chloride.
  • Examples of the acrylamide-based polymer include those obtained by copolymerizing one or more of these monomers with at least one other monomer copolymerizable by a known method.
  • Examples of other monomers capable of copolymerization include monomers that bring about other structural units other than the acrylamide-derived structural units, which will be described later.
  • the content of the acrylamide polymer in the water-absorbent resin is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, and 100% by mass. There may be.
  • some or all of the ionic groups (eg, carboxyl groups) of the acrylamide polymer may be in the form of salts (carboxylates if the ionic groups are carboxyl groups).
  • salt counter cations are alkali metal ions such as lithium ion, sodium ion, potassium ion, rubidium ion, and cesium ion; alkaline earth metal ions such as magnesium ion, calcium ion, strontium ion, and barium ion; Examples thereof include aluminum ions and other metal ions such as zinc ions; onium cations such as ammonium ions, imidazoliums, pyridiniums, and phosphonium ions; and the like.
  • potassium ion, ammonium ion, calcium ion, and magnesium ion are preferable from the viewpoint of easily obtaining a more preferable water absorption amount or water absorption rate.
  • Potassium ions and ammonium ions are more preferable from the viewpoint of plant growth, and calcium ions are more preferable from the viewpoint of easily maintaining the amount of liquid absorbed or the rate of liquid absorption even when in contact with divalent ions contained in the soil.
  • the content of the ionic group in the acrylamide-based polymer is 0.1 mol% or more, preferably 1 mol% or more, more preferably 3 mol% or more, still more preferably 3 mol% or more, based on all the constituent units of the acrylamide-based polymer. 4 mol% or more, particularly preferably 5 mol% or more, 50 mol% or less, preferably 40 mol% or less, more preferably 30 mol% or less, still more preferably 25 mol% or less, still more preferably 20 mol%.
  • it is particularly preferably 15 mol% or less, and further particularly preferably 10 mol% or less.
  • the acrylamide-based polymer tends to have a higher water absorption amount or water absorption rate.
  • the content of the ionic group is not more than the upper limit, the acrylamide polymer can easily maintain an excellent liquid absorption amount or liquid absorption rate even when in contact with divalent ions contained in the soil. The amount of liquid absorbed or the rate of liquid absorption is unlikely to decrease over a long period of time, and decomposition of the acrylamide polymer by ultraviolet rays is unlikely to occur.
  • the amount of the carboxyl group derived from acrylamide or a salt thereof among the above-mentioned carboxyl groups is preferably 20 with respect to all the constituent units of the acrylamide-based polymer. It is mol% or less, more preferably 15 mol% or less, particularly preferably 10 mol% or less, and may be 0 mol%.
  • the amount of the carboxyl group derived from acrylamide or a salt thereof among the above-mentioned carboxyl groups is not more than the upper limit value, more excellent weather resistance (particularly ultraviolet resistance) can be easily obtained.
  • more than half of the ionic groups contained in the acrylamide polymer are in the form of derivatives, and in a more preferred embodiment, most of the ionic groups contained in the acrylamide polymer are in the form of derivatives. Yes, and in one particularly preferred embodiment, all of the ionic groups contained in the acrylamide polymer are in the form of derivatives.
  • the content of the acrylamide-derived structural unit of the acrylamide-based polymer is preferably more than 20 mol%, more preferably 50 mol% or more, still more preferably 60 mol% or more with respect to all the structural units of the acrylamide-based polymer. It is preferably 98 mol% or less, more preferably 95 mol% or less, still more preferably 90 mol% or less.
  • the acrylamide-based polymer contains other structural units other than the acrylamide-derived structural unit.
  • Examples of the above other building blocks include vinyl alcohol units; building blocks derived from vinyl carboxylates such as vinyl acetate and vinyl pivalate; building blocks derived from olefins such as ethylene, 1-butene, and isobutylene; acrylic acid and Derivatives thereof, methacrylic acid and its derivatives, methacrylicamide and its derivatives, maleic acid and its derivatives, structural units derived from maleimide derivatives and the like; and the like can be mentioned.
  • the other constituent units may contain one kind or a plurality of kinds.
  • the content of the other structural units is preferably 50 mol% or less, more preferably 30 mol% or less, still more preferably 20 mol% or less, still more preferably 10 with respect to all the structural units of the acrylamide-based polymer.
  • Mol% or less particularly preferably 5 mol% or less, preferably 0.1 mol% or more, more preferably 0.5 mol% or more, still more preferably 1 mol% or more, still more preferably 2 mol% or more, Particularly preferably, it is 3 mol% or more.
  • the content of the other structural units is at least the lower limit value and at least the upper limit value, it is easy to obtain a better water absorption amount or water absorption rate of the water retention material of the present invention.
  • the weight average molecular weight of the acrylamide polymer is not particularly limited, but from the viewpoint of ease of production, it is preferably 1,000,000 or less, more preferably 5,000,000 or less, still more preferably 3,000,000 or less. , Particularly preferably 1,000,000 or less.
  • the weight average molecular weight is preferably 1000 or more, more preferably 5000 or more, still more preferably 10,000 or more.
  • the weight average molecular weight of the acrylamide polymer can be measured by, for example, GPC.
  • the weight average molecular weight can be measured after the crosslinked structure is cut. ..
  • the cutting can be performed by a general method (for example, hydrolysis using an acid or an alkali).
  • the acrylamide polymer preferably contains a crosslinked structure from the viewpoint of suppressing elution of the acrylamide polymer due to irrigation.
  • the form of the cross-linked structure is not particularly limited, and examples thereof include a cross-linked structure using a general cross-linking agent.
  • the presence or absence of the crosslinked structure in the acrylamide-based polymer can be examined by, for example, the elution rate in hot water or dimethyl sulfoxide at 100 ° C.
  • the crosslinked structure may be formed at the same time as the copolymerization reaction in the copolymerization step of, for example, the monomer resulting in the acrylamide-derived structural unit and the monomer resulting in other structural units other than the acrylamide-derived structural unit, or may be formed at the same time as the copolymerization reaction step. In another step, it may be formed before the aggregation step by further adding a cross-linking agent before the aggregation step described later, or it may be formed at the same time as the aggregation step by further adding a cross-linking agent in the aggregation step. It may be formed after the aggregation step by further adding a cross-linking agent after the aggregation step. In the present invention, it is preferable to form a crosslinked structure by further adding a crosslinking agent.
  • cross-linking agents examples include N, N'-methylenebisacrylamide, divinylbenzene, ethylene glycol diglycidyl ether, pentaerythritol triallyl ether, pentaerythritol triacrylate, pentaerythritol tetraacrylate, 1,6-hexanediol diacrylate, 1,9-Nonandiol diacrylate, 1,10-decanediol diacrylate, neopentyl glycol diacrylate, 2-hydroxy-3-methacrylicpropyl acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, trimethyl propanetriacrylate and Tris- (2-acryloxyethyl) isocyanurate and the like can be mentioned.
  • the amount of the cross-linking agent in the acrylamide-based polymer is preferably 0.001 mol% or more, more preferably 0.005 mol% or more, from the viewpoint of easily maintaining water retention in the soil. More preferably 0.01 mol% or more, still more preferably 0.03 mol% or more, preferably 0.5 mol% or less, more preferably 0.4 mol% or less, still more preferably 0.3 mol. % Or less.
  • the acrylamide-based polymer include a crosslinked product of an acrylamide-acrylic acid-sodium acrylate copolymer and a crosslinked product of an acrylamide-acrylic acid-potassium acrylate copolymer.
  • examples of commercially available products include Miracle-Gro (registered trademark) water storing crystal (manufactured by ScottsMiracle-Gro) and Aquasorb (registered trademark) (manufactured by SNF Holding Company).
  • methacrylic acid-based polymer that may be contained in the water-absorbent resin in the present invention
  • the structural unit derived from methacrylic acid or a methacrylic acid derivative (hereinafter referred to as “methacrylic acid-derived structural unit”) is the most among all the structural units. Contains high content.
  • Examples of raw materials for methacrylic acid-based polymers include methacrylic acid, sodium methacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, propyl methacrylate, isopropyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and methacrylic acid ( 2-Ethylhexyl), methacrylic acid (t-butylcyclohexyl), benzyl methacrylate and methacrylic acid (2,2,2-trifluoroethyl) and trimethyl [3- (methacryloylamino) propyl] aminium chloride can be mentioned. ..
  • Examples of the methacrylic acid-based polymer include those obtained by copolymerizing one or more of these monomers with at least one other monomer copolymerizable by a known method.
  • Examples of other monomers capable of copolymerization include monomers that bring about other structural units other than the methacrylic acid-derived structural units, which will be described later.
  • the content of the methacrylic acid polymer in the water-absorbent resin is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, and 100% by mass. May be.
  • a part or all of the ionic group (for example, carboxyl group) contained in the methacrylic acid polymer is in the form of a salt (carboxylate when the ionic group is a carboxyl group). May be good.
  • salt counter cations are alkali metal ions such as lithium ion, sodium ion, potassium ion, rubidium ion, and cesium ion; alkaline earth metal ions such as magnesium ion, calcium ion, strontium ion, and barium ion; Examples thereof include aluminum ions and other metal ions such as zinc ions; onium cations such as ammonium ions, imidazoliums, pyridiniums, and phosphonium ions; and the like.
  • potassium ion, ammonium ion, calcium ion, and magnesium ion are preferable from the viewpoint of easily obtaining a more preferable water absorption amount or water absorption rate.
  • Potassium ions and ammonium ions are more preferable from the viewpoint of plant growth, and calcium ions are more preferable from the viewpoint of easily maintaining the amount of liquid absorbed or the rate of liquid absorption even when in contact with divalent ions contained in the soil.
  • the content of the ionic group in the methacrylic acid-based polymer is 0.1 mol% or more, preferably 1 mol% or more, more preferably 3 mol% or more, and further, with respect to all the constituent units of the methacrylic acid-based polymer. It is preferably 4 mol% or more, particularly preferably 5 mol% or more, 50 mol% or less, preferably 40 mol% or less, more preferably 30 mol% or less, still more preferably 25 mol% or less, still more preferably 20. It is mol% or less, particularly preferably 15 mol% or less, and even more preferably 10 mol% or less.
  • the methacrylic acid-based polymer tends to have a higher water absorption amount or water absorption rate.
  • the content of the ionic group is not more than the upper limit, the methacrylic acid-based polymer can easily maintain an excellent liquid absorption amount or liquid absorption rate even when in contact with divalent ions contained in the soil. This liquid absorption amount or liquid absorption rate is unlikely to decrease over a long period of time, and decomposition of the methacrylic acid-based polymer by ultraviolet rays is unlikely to occur.
  • the amount of the carboxyl group derived from methacrylic acid or a salt thereof among the above-mentioned carboxyl groups is relative to all the constituent units of the methacrylic acid-based polymer. It is preferably 20 mol% or less, more preferably 15 mol% or less, particularly preferably 10 mol% or less, and may be 0 mol%.
  • the amount of the carboxyl group derived from methacrylic acid or a salt thereof among the above-mentioned carboxyl groups is not more than the upper limit value, more excellent weather resistance (particularly ultraviolet resistance) can be easily obtained.
  • more than half of the ionic groups contained in the methacrylic acid polymer are in the form of derivatives, and in a more preferred embodiment, most of the ionic groups contained in the methacrylic acid polymer are derivatives. In one particularly preferred embodiment, all of the ionic groups contained in the methacrylic acid polymer are in the form of derivatives.
  • the content of the methacrylic acid-derived structural unit of the methacrylic acid-based polymer is preferably more than 20 mol%, more preferably 50 mol% or more, still more preferably 60 mol% with respect to all the structural units of the methacrylic acid-based polymer.
  • the above is preferably 98 mol% or less, more preferably 95 mol% or less, still more preferably 90 mol% or less.
  • the methacrylic acid-based polymer contains other structural units other than the methacrylic acid-derived structural unit.
  • Examples of the above other building blocks include vinyl alcohol units; building blocks derived from vinyl carboxylates such as vinyl acetate and vinyl pivalate; building blocks derived from olefins such as ethylene, 1-butene, and isobutylene; acrylic acids and Constituent units derived from its derivatives, acrylamide and its derivatives, methacrylicamide and its derivatives, maleic acid and its derivatives, maleimide derivatives and the like; and the like can be mentioned.
  • the other constituent units may contain one type or a plurality of types.
  • the content of the other structural units is preferably 50 mol% or less, more preferably 40 mol% or less, still more preferably 30 mol% or less, still more preferably 30 mol% or less, based on all the structural units of the methacrylic acid-based polymer. 20 mol% or less, particularly preferably 10 mol% or less, preferably 0.1 mol% or more, more preferably 0.5 mol% or more, still more preferably 1 mol% or more, still more preferably 2 mol% or more. , Particularly preferably 3 mol% or more.
  • the content of the other structural units is at least the lower limit value and at least the upper limit value, it is easy to obtain a better water absorption amount or water absorption rate of the water retention material of the present invention.
  • the weight average molecular weight of the methacrylic acid polymer is not particularly limited, but from the viewpoint of ease of production, it is preferably 1,000,000 or less, more preferably 5,000,000 or less, still more preferably 3,000,000 or less. Below, it is particularly preferably 1,000,000 or less. On the other hand, from the viewpoint of the mechanical properties of the methacrylic acid polymer and the elution resistance to water, the weight average molecular weight is preferably 1000 or more, more preferably 5000 or more, still more preferably 10,000 or more.
  • the weight average molecular weight of the methacrylic acid polymer can be measured by, for example, GPC.
  • the weight average molecular weight should be measured after the crosslinked structure is cut. Can be done.
  • the cutting can be performed by a general method (for example, hydrolysis using an acid or an alkali).
  • the methacrylic acid-based polymer preferably contains a crosslinked structure from the viewpoint of suppressing elution of the methacrylic acid-based polymer due to irrigation.
  • the form of the cross-linked structure is not particularly limited, and examples thereof include a cross-linked structure using a general cross-linking agent.
  • the presence or absence of the crosslinked structure in the methacrylic acid-based polymer can be examined by, for example, the elution rate in hot water or dimethyl sulfoxide at 100 ° C.
  • the crosslinked structure may be formed at the same time as the copolymerization reaction in the copolymerization step of, for example, a monomer which brings about a structural unit derived from methacrylic acid and a monomer which brings about a structural unit other than the structural unit derived from methacrylic acid, or the copolymerization reaction. It may be formed before the aggregation step by further adding a cross-linking agent before the aggregation step described later in another step other than the step, or it may be formed by further adding the cross-linking agent in the aggregation step. It may be formed at the same time, or it may be formed after the aggregation step by further adding a cross-linking agent after the aggregation step. In the present invention, it is preferable to form a crosslinked structure by further adding a crosslinking agent.
  • cross-linking agents examples include N, N'-methylenebisacrylamide, divinylbenzene, ethylene glycol diglycidyl ether, pentaerythritol triallyl ether, pentaerythritol tri and tetraacrylate, 1,6-hexanediol diacrylate, 1,9.
  • Nonandiol diacrylate 1,10-decanediol diacrylate, neopentyl glycol diacrylate, 2-hydroxy-3-methacrylicpropyl acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, trimethylolpropane triacrylate and tris- ( 2-Acryloxyethyl) isocyanurate and the like can be mentioned.
  • the amount of the cross-linking agent in the methacrylic acid-based polymer is preferably 0.001 mol% or more, more preferably 0.005 mol%, from the viewpoint of easily maintaining water retention in the soil.
  • the above is more preferably 0.01 mol% or more, still more preferably 0.03 mol% or more, preferably 0.5 mol% or less, more preferably 0.4 mol% or less, still more preferably 0.3. It is less than mol%.
  • methacrylic acid-based polymer examples include a crosslinked product of a methacrylic acid-sodium methacrylate copolymer and a crosslinked product of a methacrylic acid-sodium methacrylate-acrylic acid copolymer.
  • the water-retaining material of the present invention may optionally contain an additive in addition to the water-absorbent resin.
  • additives are polysaccharides such as starch, modified starch, sodium alginate, chitin, chitosan, cellulose and derivatives thereof; ethylene-propylene copolymer, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene.
  • additives may be used alone or in combination of two or more. Further, all the resins listed as examples of additives are different from the water-absorbent resin of the present invention.
  • the total content thereof may be as long as it does not impair the effect of the present invention, and is usually 20% by mass or less, preferably 15% by mass or less, based on the total mass of the water-retaining material. More preferably, it is 10% by mass or less, for example, 5% by mass or less.
  • a component in a water-retaining material or a medium described later that is, a water-absorbent resin, an optional additive described above, or an optional component (Z) described later], or a component used in a manufacturing process described later (for example, a water-absorbent resin, etc.)
  • the content or mass is based on the dry mass.
  • the "dry state” means a state in which the constituent component does not contain a volatile component such as water or an organic solvent. For example, they can be put into a dry state by vacuum drying at 40 ° C. until the mass of each of the constituents becomes constant.
  • the agricultural water-retaining material of the present invention can be used as a medium in combination with an arbitrary component (Z) as needed, and among them, for example, it can be used as a medium for raising seedlings. Therefore, in one embodiment, the water-retaining material of the present invention is for raising seedlings. Since the water-retaining material of the present invention can exhibit an excellent water absorption rate, when used as a medium, it suppresses a decrease in water utilization efficiency due to water flowing out before the water-retaining material absorbs water during irrigation. be able to.
  • the medium may exhibit a sufficient water absorption rate. can.
  • Examples of such an arbitrary component (Z) include resins other than the water-absorbent resin contained in the water-retaining material, hilling, other optional components described later, and combinations thereof.
  • Resin other than water-absorbent resin examples include polyethylene, polypropylene, alkyd resin, phenolic resin, polyethylene glycol, and polyurethane. These resins can be used alone or in combination of two or more.
  • the total content thereof is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less, based on the total mass of the medium.
  • the roots grow in the gaps of the hilling soil so that the roots can be appropriately entangled with each other, and the excellent drainage and air permeability of the medium can be easily obtained.
  • the hilling is not particularly limited, and for example, one kind of commercially available hilling can be used alone or in combination of two or more kinds.
  • other optional components described later may be attached to the soil by a conventional method (for example, a method of spraying a solution or dispersion of the other optional components on the soil and then drying it) and using the soil.
  • the soil is granular.
  • the particle size of the granular soil is preferably 0.2 to 20 mm, more preferably 0.5 to 10 mm, and particularly preferably 1 to 5 mm.
  • a commercially available granular hilling can be sieved and used.
  • a granulation method such as a compression granulation method, an extrusion granulation method, a rolling granulation method, or a fluidized bed granulation method can be used.
  • the particle size of the granular soil can be measured by the following method.
  • the diameter of each particle is measured using a caliper, and the average value is taken as the particle size of the granular culture soil. If the particle is not spherical, the average value of the longest side and the shortest side is taken as the diameter of the particle.
  • the content of the soil is preferably 20 to 99.9999% by mass, more preferably 70 to 99.95% by mass, and particularly preferably 80 to 99.9, based on the total mass of the medium. It is by mass, most preferably 90 to 99.8% by mass.
  • optional ingredients examples include peat, grass charcoal, peat, peat moss, coco peat, rice husks, fertilizer materials, charcoal, diatomaceous earth calcined grains, shell fossil powder, shell powder, crab shells, VA mycorrhizal fungi, microbial materials, etc. Fauna and flora; vermiculite, pearlite, bentonite, natural zeolite, synthetic zeolite, peat, fly ash, rock wool, kaolinite, smectite, montmorillonite, sericite, chlorite, gloconite and talc and other minerals; fertilizer and these The combination of can be mentioned.
  • the medium may be disinfected or sterilized as needed, or may be used with a pH regulator or pesticide.
  • the total content may be as long as it does not impair the effect of the present invention, and is usually 50% by mass or less, preferably 30% by mass or less, based on the total mass of the medium. be.
  • fertilizers are nitrogen-based fertilizers, phosphorus-based fertilizers, and potassium-based fertilizers; essential elements for plants such as calcium, magnesium, sulfur, iron, copper, manganese, zinc, boron, molybdenum, chlorine, and nickel.
  • nitrogen-based fertilizers include sulfur-an, salt-an, glass-an, sodium nitrate, lime nitrate, ammonia fertilizer, urea, lime nitrogen, ammonia lime nitrate, ammonia sodium nitrate and fertilizer with nitrate; phosphorus.
  • system fertilizers include perphosphate lime, heavy perphosphate lime, molten phosphoric acid fertilizer, rotten phosphate fertilizer, roasted phosphorus, heavy roasted phosphorus, phosphorus star, bitter soil perphosphate, mixed phosphate fertilizer, etc.
  • By-product phosphoric acid fertilizer and high-concentration phosphoric acid can be mentioned;
  • potassium-based fertilizer include potassium sulfate, potassium chloride, potassium sulfate bitter soil, potassium carbonate, potassium bicarbonate and potassium silicate and the like. Can be done.
  • These fertilizers may be used in the form of solids, pastes, liquids, solutions, etc., or may be used as coated fertilizers.
  • pesticides include insecticides, fungicides, insecticides, herbicides, rodenticides, preservatives, plant growth regulators and the like.
  • the fertilizer is used as a coated fertilizer.
  • the coated fertilizer is a fertilizer coated with resin.
  • This resin may be, for example, a polyolefin.
  • the coated fertilizer can be supplied to the medium over time as the resin is decomposed. Further, when mat seedlings are produced using granular coated fertilizer, the strength of the obtained mat seedlings tends to be high.
  • the particle size of the coated fertilizer is preferably 1 mm to 10 mm, more preferably 3 mm to 6 mm.
  • the content of the coated fertilizer in the medium is preferably 10 to 99.99% by mass, more preferably 15 to 90% by mass, particularly preferably 20 to 80% by mass, and most preferably 30 to 60% by mass. %.
  • the water-retaining material of the present invention When the water-retaining material of the present invention is used in combination with an arbitrary component (Z), the water-retaining material and the component (Z) are mixed or used, or the water-retaining material of the present invention is contained and the component (Z) is contained. After budding in a medium, the water-retaining material of the present invention can be sprinkled on the medium for use.
  • the mixing method is not particularly limited.
  • the water retention material and the component (Z) may be mixed by a general method.
  • the sprinkling time is not particularly limited, but it is preferable that the plant is vulnerable to drought during the seedling raising period (approximately one month after sowing).
  • the amount of the water-retaining material varies depending on the type of the component (Z) to be combined, but is usually 0.0001% by mass or more with respect to the total mass of the entire medium. It is 20% by mass, preferably 0.05% by mass to 15% by mass, and more preferably 0.1% by mass to 10% by mass.
  • Seed paddy is often sown in a paddy rice seedling box into which a paddy rice seedling medium has been introduced.
  • the amount of seed paddy is 100 to 500 g per box of paddy rice seedling raising box (length 28 cm ⁇ width 58 cm).
  • the water-retaining material of the present invention can be arbitrarily mixed with the component (Z) and used as a medium for sowing seed rice.
  • This medium may be used for either bed soil (soil introduced into the paddy rice seedling box before sowing seed rice) or soil covering (soil covered from above after sowing seed rice), or both. May be good.
  • composition of the medium may be the same or different for the bed soil and the soil cover.
  • water-retaining material of the present invention or a mixture of the water-retaining material of the present invention and the component (Z) may be sprinkled on the medium in which the seed paddy has sprouted.
  • the water absorption time (T2) of the water retention material is preferably 10 seconds or less, more preferably 7 seconds or less, still more preferably 5 seconds or less.
  • the water absorption time (T2) of the water-retaining material is the water absorption time measured by the measuring method described in Examples described later.
  • the degree of improvement in water absorption rate is preferably 1.0 or more, more preferably 2.0 or more, still more preferably 3.0 or more.
  • the degree of improvement in water absorption rate is a value calculated from the water absorption time (T1) measured by the measurement method described in Examples described later.
  • the water absorption time (T1) of the water retention material is preferably 200 seconds or less, more preferably 30 seconds or less, still more preferably 20 seconds or less.
  • the water absorption time (T1) is the water absorption time measured by the measuring method described in Examples described later.
  • the water absorption amount of the water-retaining material in the presence of the calcium salt is preferably 4 g / g or more, more preferably 6 g / g or more, still more preferably 8 g / g or more.
  • the amount of water absorbed in the presence of the calcium salt of the water-retaining material can be measured by a liquid absorption test using an aqueous solution of calcium chloride as described in Examples described later.
  • the water-retaining material of the present invention is, for example, Manufactured by a manufacturing method including a coagulation step of agglomerating a water-absorbent resin existing as primary particles by contacting them in a swollen state, and a drying step of drying the agglomerated water-absorbent resin under a pressure of 0.2 MPa or less.
  • this manufacturing method may be referred to as a manufacturing method according to the first embodiment of the present invention.
  • the primary particles will be described.
  • particles that are not aggregated are referred to as "primary particles" for convenience.
  • particles obtained by melting or dissolving a water-absorbent resin in a solvent and then drying and pulverizing particles obtained by polymerizing a monomer in a melted or dissolved state in a solvent, drying and pulverizing, or (coagulation). It refers to a commercially available water-absorbent resin (not an aggregate) or particles obtained by crushing it.
  • the primary particles are not limited to spherical particles, but may be irregular particles such as those obtained by pulverization.
  • the particle size of the primary particles is as described in the above-mentioned explanation of "agricultural water retention material”.
  • the water-absorbent resin existing as the primary particles is agglomerated by contacting them in a swollen state.
  • a water-absorbent resin in which the average particle size of the primary particles is adjusted by pulverization and / or sieving may be used, if necessary.
  • any of the above-mentioned additives may be mixed with the water-absorbent resin before the aggregation step, at the same time as the aggregation step, or after the aggregation step.
  • the water content of the water-absorbent resin existing as primary particles before swelling the water-absorbent resin is preferably 15% by mass or less, more preferably 13% by mass or less, still more preferably 10% by mass. % Or less, particularly preferably 5% by mass or less.
  • the lower limit of the water content is not particularly limited and is 0% by mass or more.
  • the water content can be calculated using the mass of the water-absorbent resin and the mass of the water-absorbent resin after it has been dried until it becomes dry.
  • the water-absorbent resin existing as primary particles is swollen with a swelling solvent (for example, water, methanol, ethanol, propanol, dimethyl sulfoxide, N-methylpyrrolidone or acetic acid, preferably water).
  • a swelling solvent for example, water, methanol, ethanol, propanol, dimethyl sulfoxide, N-methylpyrrolidone or acetic acid, preferably water.
  • the water-absorbent resin can be uniformly swelled by spraying the swelling solvent in a mist state using a spray or the like.
  • the amount of the swelling solvent to be sprayed is preferably 1% by mass to 500% by mass, more preferably 5% by mass, based on the mass of the water-absorbent resin, from the viewpoint of easily obtaining a preferable particle size and / or cohesive force of the water-retaining material. It is ⁇ 100% by mass, more preferably 10% by mass to 50% by mass.
  • the resin After spraying, the resin is agitated to improve the uniformity of swelling, but agitation with a high shear force, for example, a stirrer equipped with a stirring blade that rotates at high speed, causes crushing or disintegration of once agglomerated particles.
  • a high shear force for example, a stirrer equipped with a stirring blade that rotates at high speed
  • stirring with a low shearing force for example, stirring by a method of putting in a bag and shaking, or stirring with a conical mixer or the like is preferable.
  • the shear force is preferably 10000 MPa or less, more preferably 100 MPa or less, still more preferably 1 MPa or less.
  • the contact time is preferably 0.001 seconds or longer, more preferably 0.1 seconds or longer, still more preferably 1 second or longer.
  • any additive may be added before the agglomeration step or at the same time as the agglomeration step, and the strength of the agglomeration of the water-absorbent resin can be adjusted by adding a binder.
  • binders include polymer components other than water-absorbent resins, such as polyvinyl alcohol, ethylene-vinyl alcohol copolymers, polyvinyl butyral, starch, cellulose, polyethylene oxide, polyethylene glycol, carboxymethyl cellulose, polyacrylic acid and salts thereof. , Polyacrylamide, acrylic acid and its salts and copolymers of acrylamide, styrene butadiene rubber and the like.
  • One type of binder may be used alone, or two or more types may be used in combination.
  • the amount of the binder added is usually 10% by mass or less, preferably 5% by mass or less, more preferably 5% by mass or less, based on the total mass of the water-absorbent resin, the swelling solvent, the binder, and any additive other than the binder if present. It is 1% by mass or less, more preferably 0.5% by mass or less, and may be 0% by mass.
  • the aggregated water-absorbent resin is dried using a dryer under a pressure of 0.2 MPa or less, preferably 0.15 MPa or less, more preferably 0.1 MPa or less, for example, under vacuum.
  • a general dryer can be used, and examples thereof include a conical dryer and a hot air dryer.
  • the drying temperature depends on the water-absorbent resin used, but is usually 20 to 150 ° C, preferably 40 to 100 ° C.
  • the drying time may be appropriately selected so that the obtained water-retaining material is in a dry state, and is usually 1 to 1440 minutes, preferably 5 to 720 minutes. Further, if necessary, any of the above-mentioned additives may be mixed with the aggregated water-absorbent resin before the drying step, at the same time as the drying step, or after the drying step.
  • the swelling solvent may be completely removed, but from the viewpoint of suppressing disintegration, a part of the swelling solvent may remain.
  • the amount of the swelling solvent to be left is preferably 50% by mass or less with respect to the mass of the water-absorbent resin.
  • the production method may further include a cross-linking step of cross-linking the water-absorbent resin before the agglomeration step, at the same time as the agglomeration step, or after the agglomeration step. From the viewpoint of easily obtaining an excellent water absorption rate, it is preferable to include a cross-linking step of cross-linking the water-absorbent resin before the aggregation step. In this case, the crosslinked water-absorbent resin is agglomerated by contacting it in a swollen state, but the cohesive force is not excessively strong.
  • the expansion and disintegration of the water-retaining material proceed in a well-balanced manner during water absorption, and a more preferable water absorption rate can be obtained. Further, it becomes easy to increase the proportion of the crosslinked structure on the surface of the water-absorbent resin, and as a result, from the viewpoint of easily obtaining a low elution rate of the water-absorbent resin from the water-retaining material and / or from the viewpoint of easily obtaining uniform cross-linking, cross-linking is performed. It is preferable that the particle size of the water-absorbent resin to be made is not more than a specific value. The particle size of the water-absorbent resin to be crosslinked can be adjusted to a desired value by sieving.
  • the particle size of the water-absorbent resin to be crosslinked is preferably 2000 ⁇ m or less, more preferably 1000 ⁇ m or less, still more preferably 700 ⁇ m or less, and particularly preferably 150 ⁇ m or less.
  • the particle size of the water-absorbent resin to be crosslinked is preferably 5000 ⁇ m or less, more preferably 3000 ⁇ m or less, and particularly preferably 2000 ⁇ m or less.
  • the particle size when the cross-linking step is carried out at the same time as the coagulation step refers to the particle size at the time when the cross-linking step and the coagulation step are completed.
  • the water-retaining material of the present invention can also be produced, for example, by a production method including a coagulation step in which water-absorbent resins existing as particles are agglomerated by contacting them in a swollen state.
  • this manufacturing method may be referred to as a manufacturing method according to the second embodiment of the present invention.
  • the "particles" in the production method of the second embodiment include non-aggregated particles such as the primary particles in the production method of the first embodiment, and aggregates in which the primary particles are aggregated (scientifically, secondary particles). Any of the particles (sometimes called) are included as a concept. That is, in the production method of the second embodiment, the "particles" include non-aggregated particles, aggregated particles in which non-aggregated particles are aggregated, or non-aggregated particles and aggregated particles. It is also possible to use any of the mixtures of.
  • the particles include, for example, particles obtained by polymerizing in a suspended or emulsified state, particles obtained by spray-drying a resin solution, commercially available particulate water-absorbent resin, or particles obtained by crushing them. , Primary particles used in the production method of the first embodiment, particles in which primary particles are aggregated, a mixture thereof, and the like.
  • the particles may be not only spherical particles such as those obtained by polymerization in a suspended or emulsified state, but also irregularly shaped particles such as those obtained by grinding.
  • the particle size of the particles is preferably 1 ⁇ m or more, more preferably 10 ⁇ m or more, still more preferably 30 ⁇ m or more, particularly preferably 50 ⁇ m or more, preferably 3000 ⁇ m or less, more preferably 1000 ⁇ m or less, still more preferably 600 ⁇ m or less, and particularly preferably. Is 300 ⁇ m or less.
  • the average particle diameter of the particles is at least the lower limit value and at least the upper limit value, a more preferable water absorption rate can be easily obtained. Further, when the average particle diameter of the particles is at least the above lower limit value, it is easy to suppress the generation of dust during the production of the water-retaining material.
  • the average particle size of the particles can be measured, for example, using an electron microscope or a sieve with a specific opening.
  • the water-absorbent resin existing as particles is agglomerated by contacting them in a swollen state.
  • a water-absorbent resin in which the average particle size of the particles is adjusted by pulverization and / or sieving may be used, if necessary.
  • any of the above-mentioned additives may be mixed with the water-absorbent resin before the aggregation step, at the same time as the aggregation step, or after the aggregation step.
  • the water content of the water-absorbent resin existing as particles before swelling the water-absorbent resin is preferably 15% by mass or less, more preferably 13% by mass or less, and particularly preferably 10% by mass. It is as follows. When the water content is not more than the upper limit value, good handleability can be easily obtained.
  • the lower limit of the water content is not particularly limited and is 0% by mass or more.
  • the water content can be calculated using the mass of the water-absorbent resin and the mass of the water-absorbent resin after it has been dried until it becomes dry, and can be calculated, for example, by the method described in Examples described later.
  • the swelling solvent used in the aggregation step of the production method of the second embodiment, the swelling method, the amount of the swelling solvent with respect to the mass of the water-absorbent resin, the stirring method, the stirrer, and the shearing force at the time of stirring are determined by the manufacturing method of the first embodiment. It is possible to adopt the same process as the aggregation process of.
  • Any additive may be added before the agglomeration step or at the same time as the agglomeration step, and the strength of the agglomeration of the water-absorbent resin can be adjusted by adding a binder.
  • a binder As the type and amount of the binder that can be used, those of the production method of the first embodiment can be adopted.
  • the production method may further include a cross-linking step of cross-linking the water-absorbent resin before the agglomeration step, at the same time as the agglomeration step, or after the agglomeration step. From the viewpoint of easily obtaining an excellent water absorption rate, it is preferable to include a cross-linking step of cross-linking the water-absorbent resin before the aggregation step. In this case, the crosslinked water-absorbent resin is agglomerated by contacting it in a swollen state, but the cohesive force is not excessively strong.
  • the expansion and disintegration of the water-retaining material proceed in a well-balanced manner during water absorption, and a more preferable water absorption rate can be obtained. Further, it becomes easy to increase the proportion of the crosslinked structure on the surface of the water-absorbent resin, and as a result, from the viewpoint of easily obtaining a low elution rate of the water-absorbent resin from the water-retaining material and / or from the viewpoint of easily obtaining uniform cross-linking, cross-linking is performed. It is preferable that the particle size of the water-absorbent resin to be made is not more than a specific value. The particle size of the water-absorbent resin to be crosslinked can be adjusted to a desired value by sieving.
  • the particle size of the water-absorbent resin to be crosslinked is preferably 3000 ⁇ m or less, more preferably 1000 ⁇ m or less, still more preferably 600 ⁇ m or less, and particularly preferably 300 ⁇ m or less.
  • the particle size of the water-absorbent resin to be crosslinked is preferably 5000 ⁇ m or less, more preferably 3000 ⁇ m or less, and particularly preferably 2000 ⁇ m or less.
  • the particle size when the cross-linking step is carried out at the same time as the coagulation step refers to the particle size at the time when the cross-linking step and the coagulation step are completed.
  • Peak derived from methyl carbon of vinyl ester group of vinyl acetate unit (usually observed at 10 to 30 ppm), peak derived from methylene carbon of ethylene unit (usually observed at 30 to 50 ppm), acrylic acid And ions contained in the resin from the peak derived from the carbonyl carbon of the methacrylic acid unit (usually observed at 170-180 ppm) and the peak derived from the carbonyl carbon of the acrylamide unit (usually observed at 160-180 ppm).
  • a water-retaining material as a sample is dispersed in a dispersion medium, and a laser diffraction / scattering type particle size distribution measuring device LA-950V2 (manufactured by Horiba Seisakusho) is used to measure the average particle size and volume-based 10% particle size D 10 (ultrasonic waves). (Equivalent to D10 of the water - retaining material before application) was measured. Next, the water-retaining material is swelled by absorbing the dispersion medium into the water-retaining material by ultrasonic irradiation for 5 minutes, and then the volume-based 10% particle diameter D 10 of the water-retaining material (of the water-retaining material after applying ultrasonic waves).
  • the rate of change of the volume-based 10% particle diameter D 10 of the water-retaining material before and after applying ultrasonic waves was calculated by the following formula.
  • Each of the above-mentioned measurements was performed twice for one sample, and the obtained measured value and the average value of the D 10 rate of change were adopted as the measured value and the D 10 rate of change for the sample.
  • Water absorption time (T1) water absorption speed improvement> 0.12 g of a water-retaining material was put into a petri dish having a diameter of 3.5 cm, and 3.0 g of pure water was added with a pipette over 0.5 seconds. The time from when the water was added until the water-retaining material absorbed water and the water surface disappeared was measured. The shorter this time, the faster the water absorption rate of the water retention material. Further, in order to evaluate the degree of improvement in the water absorption rate due to the D 10 change rate of the water retention material being 1 or less, as shown in the following formula, the D 10 change rate of the water retention material is 1 or less as the water absorption rate improvement degree.
  • Water absorption time (T2)> Put Xg of water-retaining material evenly in a petri dish with a diameter of 3.5 cm so that the mass of the water-absorbent resin is 0.12 g, and add pure water Yg with a pipette so that the water content is 3 mL together with the water contained in the water-retaining material. I put it all at once. The time from when the water was added until the water-retaining material absorbed water and the water surface disappeared was measured and used as the water absorption time (T2). The shorter this time, the faster the water absorption rate of the water retention material.
  • Water-absorbent resin As the water-absorbent resin (A1), Aquasorb 3005KB (acrylamide-based polymer, non-aggregate particulate matter, average particle diameter 644 ⁇ m, crosslinked structure) manufactured by SNF Holding Company was used. The content of the ionic group with respect to all the constituent units of the water-absorbent resin (A1) was 22 mol%. As the water-absorbent resin (A2), Aquasorb 3005KB (acrylamide-based polymer, non-aggregate particulate matter, average particle diameter 644 ⁇ m, crosslinked structure) manufactured by SNF Holding Company was used. The content of the ionic group with respect to all the constituent units of the water-absorbent resin (A2) was 22 mol%. An acrylic acid-based polymer (particulate) was used as the water-absorbent resin (C1). The content of the ionic group with respect to all the constituent units of the water-absorbent resin (C1) was 54 mol%.
  • a vinyl alcohol-based polymer [water-absorbent resin (B1)] was synthesized by the following procedure. 9030 g of vinyl acetate, 18.15 g of methyl acrylate, and 3810 g of methanol were introduced into a reactor equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, and an initiator addition port, and the reaction was carried out for 30 minutes while nitrogen bubbling. The inside of the vessel was replaced with an inert gas. The temperature of the reactor was started using a water bath, and when the internal temperature of the reactor reached 60 ° C., 2.40 g of azobisisobutyronitrile (AIBN) was added as an initiator to initiate polymerization. ..
  • AIBN azobisisobutyronitrile
  • the progress of the polymerization was confirmed from the solid content concentration by appropriately sampling, and the consumption rate, which is the total mass of vinyl acetate and methyl acrylate consumed by the polymerization, with respect to the total mass of the introduced vinyl acetate and methyl acrylate was calculated. I asked.
  • the consumption rate reached 4% by mass
  • the internal temperature of the reactor was cooled to 30 ° C. to terminate the polymerization. It was connected to a vacuum line, and the residual vinyl acetate was distilled off under reduced pressure at 30 ° C. together with methanol. While visually checking the inside of the reactor, when the viscosity increased, distillation was continued while appropriately adding methanol to obtain polyvinyl acetate containing 5.2 mol% of acrylic acid-derived structural units.
  • the content of acrylic acid-derived structural units was measured using solid 13 C-NMR.
  • 360 g of the obtained polyvinyl acetate containing a structural unit derived from acrylic acid and 6552 g of methanol were added to the same reactor as described above, and the obtained polyvinyl acetate containing a structural unit derived from acrylic acid was dissolved.
  • the temperature of the reactor was started by using a water bath, and the reactor was heated with stirring until the internal temperature of the reactor reached 70 ° C.
  • 280.8 g of a methanol solution of sodium hydroxide metal-caustic, concentration 15% by mass
  • polyvinyl alcohol (b1) polyvinyl alcohol containing 5.2 mol% of acrylic acid-derived structural units.
  • the washed polymer is introduced into a three-neck separable flask equipped with a reflux condenser and a stirring blade, 245 g of methanol, 40.8 g of pure water, and 24.35 g of 50% by mass potassium hydroxide are added, and the temperature is 65 ° C. It was allowed to react for 2 hours. After the reaction, the polymer was taken out by filtration, and then the collected polymer was dispersed in 330 g of methanol, stirred for 30 minutes, and filtered for washing. Washing was repeated twice. The washed polymer was vacuum dried at 40 ° C. for 12 hours to obtain the desired water-absorbent resin (B1). The content of the ionic group with respect to all the constituent units of the water-absorbent resin (B1) was 5 mol%.
  • a vinyl alcohol-based polymer [water-absorbent resin (B2)] was synthesized by the following procedure. 9030 g of vinyl acetate, 18.15 g of methyl acrylate, and 3810 g of methanol were introduced into a reactor equipped with a stirrer, a reflux cooling tube, a nitrogen introduction tube, and an initiator addition port, and the reaction was carried out for 30 minutes while nitrogen bubbling. The inside of the vessel was replaced with an inert gas. The temperature of the reactor was started using a water bath, and when the internal temperature of the reactor reached 60 ° C., 2.40 g of azobisisobutyronitrile (AIBN) was added as an initiator to initiate polymerization. ..
  • AIBN azobisisobutyronitrile
  • the progress of the polymerization was confirmed from the solid content concentration by appropriately sampling, and the consumption rate, which is the total mass of vinyl acetate and methyl acrylate consumed by the polymerization, with respect to the total mass of the introduced vinyl acetate and methyl acrylate was calculated. I asked.
  • the consumption rate reached 4% by mass
  • the internal temperature of the reactor was cooled to 30 ° C. to terminate the polymerization. It was connected to a vacuum line, and the residual vinyl acetate was distilled off under reduced pressure at 30 ° C. together with methanol. While visually checking the inside of the reactor, when the viscosity increased, distillation was continued while appropriately adding methanol to obtain polyvinyl acetate containing 5.2 mol% of acrylic acid-derived structural units.
  • the content of acrylic acid-derived structural units was measured using solid 13 C-NMR.
  • 360 g of the obtained polyvinyl acetate containing a structural unit derived from acrylic acid and 6552 g of methanol were added to the same reactor as described above, and the obtained polyvinyl acetate containing a structural unit derived from acrylic acid was dissolved.
  • the temperature of the reactor was started by using a water bath, and the reactor was heated with stirring until the internal temperature of the reactor reached 70 ° C.
  • 280.8 g of a methanol solution of sodium hydroxide metal-caustic, concentration 15% by mass
  • polyvinyl alcohol (b2) polyvinyl alcohol containing 5.2 mol% of acrylic acid-derived structural units was obtained.
  • the washed polymer is introduced into a three-neck separable flask equipped with a reflux condenser and a stirring blade, 245 g of methanol, 40.8 g of pure water, and 24.35 g of 50% by mass potassium hydroxide are added, and the temperature is 65 ° C. It was allowed to react for 2 hours. After the reaction, the polymer was taken out by filtration, and then the collected polymer was dispersed in 330 g of methanol, stirred for 30 minutes, and filtered for washing. Washing was repeated twice. The washed polymer was vacuum dried at 40 ° C. for 12 hours to obtain the desired water-absorbent resin (B2). The content of the ionic group with respect to all the constituent units of the water-absorbent resin (B2) was 5 mol%.
  • Examples 1 to 3 Sieved particles were collected from the water-absorbent resin (A1) using a sieve with a nominal opening of 53 ⁇ m.
  • the particle size of the collected particles is described as the particle size of " ⁇ 53" for convenience.
  • the particle size of the sieved particles is similarly described using the value of the nominal opening of the sieve.
  • Example 1 All the pure water was absorbed by the water-absorbent resin (A1) in the bag. Then, after vacuum drying at 40 ° C. for 12 hours, a sieve having a nominal opening of 300 ⁇ m, a sieve having a nominal opening of 600 ⁇ m, a sieve having a nominal opening of 1000 ⁇ m and a sieve having a nominal opening of 1400 ⁇ m were used, and the particle size was used as Example 1. Particles having a particle diameter of 300 ⁇ m to 600 ⁇ m, particles having a particle diameter of 600 ⁇ m to 1000 ⁇ m as Example 2, and particles having a particle diameter of 1000 ⁇ m to 1400 ⁇ m were obtained as Example 3, respectively.
  • Examples 4-6 Particles having a particle diameter of 53 ⁇ m to 106 ⁇ m were collected from the water-absorbent resin (A1) using a sieve having a nominal opening of 53 ⁇ m and a sieve having a nominal opening of 106 ⁇ m. Aggregates were obtained in the same manner as in Examples 1 to 3 except that 28 g of the collected particles and 12 g of pure water were used. At this time, all the pure water was absorbed by the water-absorbent resin (A1) in the bag. Then, after vacuum drying at 40 ° C.
  • Example 4 Particles having a particle diameter of 300 ⁇ m to 600 ⁇ m, particles having a particle diameter of 600 ⁇ m to 1000 ⁇ m as Example 5, and particles having a particle diameter of 1000 ⁇ m to 1400 ⁇ m were obtained as Example 6, respectively.
  • Examples 7-8 Particles having a particle diameter of 212 ⁇ m or more were collected from the water-absorbent resin (A1) using a sieve having a nominal opening of 212 ⁇ m. Aggregates were obtained in the same manner as in Examples 1 to 3 except that 28 g of the collected particles and 12 g of pure water were used. At this time, all the pure water was absorbed by the water-absorbent resin (A1) in the bag. Then, after vacuum drying at 40 ° C.
  • particles having a particle diameter of 600 ⁇ m to 1000 ⁇ m were used as Example 7 using a sieve having a nominal opening of 600 ⁇ m, a sieve having a nominal opening of 1000 ⁇ m, and a sieve having a nominal opening of 1400 ⁇ m.
  • particles having a particle diameter of 1000 ⁇ m to 1400 ⁇ m were obtained.
  • Examples 9-10 Particles having a particle diameter of 53 ⁇ m to 106 ⁇ m were collected from the water-absorbent resin (B1) using a sieve having a nominal opening of 53 ⁇ m and a sieve having a nominal opening of 106 ⁇ m. Aggregates were obtained in the same manner as in Examples 1 to 3 except that 28 g of the collected particles and 12 g of pure water were used. At this time, all the pure water was absorbed by the water-absorbent resin (A1) in the bag. Then, after vacuum drying at 40 ° C.
  • particles having a particle diameter of 300 ⁇ m to 600 ⁇ m were used as Example 9 using a sieve having a nominal opening of 300 ⁇ m, a sieve having a nominal opening of 600 ⁇ m, and a sieve having a nominal opening of 1000 ⁇ m.
  • particles having a particle diameter of 600 ⁇ m to 1000 ⁇ m were obtained.
  • Example 11 Particles having a particle diameter of 300 ⁇ m to 600 ⁇ m were collected from the water-absorbent resin (B1) using a sieve having a nominal opening of 300 ⁇ m and a sieve having a nominal opening of 600 ⁇ m. Aggregates were obtained in the same manner as in Examples 1 to 3 except that 28 g of the collected particles and 12 g of pure water were used. At this time, all the pure water was absorbed by the water-absorbent resin (A1) in the bag. Then, after vacuum drying at 40 ° C. for 12 hours, particles having a particle diameter of 600 ⁇ m to 1000 ⁇ m were obtained using a sieve having a nominal opening of 600 ⁇ m and a sieve having a nominal opening of 1000 ⁇ m.
  • Comparative Example 1 Using a sieve having a nominal opening of 300 ⁇ m and a sieve having a nominal opening of 600 ⁇ m, particles having a particle diameter of 300 ⁇ m to 600 ⁇ m were obtained from the water-absorbent resin (A1).
  • Comparative Example 5 Particles having a particle diameter of 106 ⁇ m to 212 ⁇ m were collected from the water-absorbent resin (C1) using a sieve having a nominal opening of 106 ⁇ m and a sieve having a nominal opening of 212 ⁇ m. Aggregates were obtained in the same manner as in Examples 1 to 3 except that 28 g of the collected particles and 12 g of pure water were used. At this time, all the pure water was absorbed by the water-absorbent resin (A1) in the bag. Then, after vacuum drying at 40 ° C. for 12 hours, particles having a particle size of 300 ⁇ m to 600 ⁇ m were obtained using a sieve having a nominal opening of 300 ⁇ m and a sieve having a nominal opening of 600 ⁇ m.
  • the water-absorbent resin having an ionic group of 0.1 mol% or more and 50 mol% or less with respect to all the constituent units of the water-absorbent resin constitutes a water-retaining material having a D10 change rate of 1 or less.
  • the fact that the water absorption rate was significantly improved was the degree of improvement in the water absorption rate [specifically, the ratio of the water absorption time (T1) of Example 1 or 4 to the water absorption time (T1) of Comparative Example 1 (Example). Water absorption rate improvement degree described in row 1 or 4), ratio of water absorption time (T1) of Example 2 or 5 or 7 to water absorption time (T1) of Comparative Example 2 (row of Example 2 or 5 or 7).
  • the water-retaining material of the example also showed a higher absorption amount of calcium chloride aqueous solution than the water-retaining material of the comparative example. This indicates that the water-retaining material of the present invention has a sufficiently high water absorption even in the presence of a calcium salt. In addition, the amount of water absorbed by the water-retaining material of the present invention in the presence of a calcium salt was unlikely to decrease over a long period of time.
  • Example 12 Sieved particles were collected from the water-absorbent resin (A2) using a sieve having a nominal opening of 106 ⁇ m for the water-absorbent resin (A2).
  • the particle size of the collected particles is described as the particle size of " ⁇ 106" for convenience. In the following, the particle size of the sieved particles is similarly described using the value of the nominal opening of the sieve.
  • the water-absorbent resin (A2) was water-containing at this point, and the water content was 15% by mass. The shape was particulate.
  • water-absorbent resin (A2) having a particle size of 106 ⁇ m or less and a water content of 15% by mass is placed in a bag having a length of 28 cm and a width of 20 cm, and 1.5 g of pure water is sprayed little by little each time. I shook it. At this time, instead of applying pressure to the resins to knead them, the bags were filled with air and rotated to be shaken. As a result, particles of the water-absorbent resin (A2) further contained in water were obtained. All the pure water was absorbed by the water-absorbent resin (A2) in the bag. The obtained water-containing water-absorbent resin was used as a water-retaining material for evaluation.
  • Examples 13-14 The sieve used for classification was appropriately changed to obtain a water-absorbent resin (A2) having the particle size shown in Table 2 in the same manner as in Example 12. Next, a water-retaining material was obtained in the same manner as in Example 12 except that the amount of the water-absorbent resin (A2) mixed with water was changed as shown in Table 2 according to the water content of the water-absorbent resin (A2). rice field.
  • Example 15 The water-absorbent resin (B2) was classified by a sieve having a nominal opening of 106 ⁇ m and a sieve having a nominal opening of 250 ⁇ m to obtain a water-absorbent resin (B2) having a particle size of 106 ⁇ m to 250 ⁇ m.
  • the water-absorbent resin (B2) was water-containing at this point, and the water content was 4% by mass.
  • the shape was particulate. 27 g of a water-absorbent resin (B2) having a particle size of 106 ⁇ m to 250 ⁇ m and a water content of 4% by mass was placed in the same bag as that used in Example 12, and 3 g of pure water was sprayed little by little each time.
  • Examples 16-20 The sieve used for classification was appropriately changed to obtain a water-absorbent resin (B2) having the particle size shown in Table 2 in the same manner as in Example 15. Next, a water-retaining material was obtained in the same manner as in Example 15 except that the amount of the water-absorbent resin (B2) mixed with water was changed as shown in Table 2 according to the water content of the water-absorbent resin (B2). rice field.
  • the water-retaining material of the present invention has an excellent water absorption rate, exhibits a sufficiently high water absorption amount even in the presence of a calcium salt, and the water absorption amount does not easily decrease over a long period of time, so that it can be suitably used as a water-retaining material for agriculture.

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024024706A1 (ja) * 2022-07-27 2024-02-01 三洋化成工業株式会社 植物育成用吸水性樹脂組成物

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0279911A (ja) * 1988-09-14 1990-03-20 Sanyo Chem Ind Ltd 土壌保水剤および保水方法
JPH08256592A (ja) * 1995-03-24 1996-10-08 Showa Denko Kk 人工培土
JP2007513205A (ja) * 2003-12-05 2007-05-24 株式会社日本触媒 吸水性樹脂を主成分とする粒子状植物育成用保水材
JP2010041999A (ja) * 2008-07-17 2010-02-25 Iej:Kk 植物マット
JP2015083693A (ja) * 2010-04-07 2015-04-30 株式会社日本触媒 ポリアクリル酸（塩）系吸水性樹脂粉末の製造方法及びポリアクリル酸（塩）系吸水性樹脂粉末
CN106010559A (zh) * 2016-05-31 2016-10-12 山东胜伟园林科技有限公司 一种含有膨润土的盐碱地玉米用保水剂及其制备方法
JP2018145326A (ja) * 2017-03-07 2018-09-20 株式会社クラレ 吸水性樹脂

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0279911A (ja) * 1988-09-14 1990-03-20 Sanyo Chem Ind Ltd 土壌保水剤および保水方法
JPH08256592A (ja) * 1995-03-24 1996-10-08 Showa Denko Kk 人工培土
JP2007513205A (ja) * 2003-12-05 2007-05-24 株式会社日本触媒 吸水性樹脂を主成分とする粒子状植物育成用保水材
JP2010041999A (ja) * 2008-07-17 2010-02-25 Iej:Kk 植物マット
JP2015083693A (ja) * 2010-04-07 2015-04-30 株式会社日本触媒 ポリアクリル酸（塩）系吸水性樹脂粉末の製造方法及びポリアクリル酸（塩）系吸水性樹脂粉末
CN106010559A (zh) * 2016-05-31 2016-10-12 山东胜伟园林科技有限公司 一种含有膨润土的盐碱地玉米用保水剂及其制备方法
JP2018145326A (ja) * 2017-03-07 2018-09-20 株式会社クラレ 吸水性樹脂

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024024706A1 (ja) * 2022-07-27 2024-02-01 三洋化成工業株式会社 植物育成用吸水性樹脂組成物

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