JP2009203383A - Absorbent resin particle and absorbent article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide absorbent resin particles which have a high absorption capacity under load and absorb a liquid at a high absorption speed under load, and to provide an absorbent article whose surface has high dry feeling. <P>SOLUTION: The absorbent resin particles (D) include a crosslinked polymer (A1) comprising, as essential constitutive units, a water-soluble vinyl monomer (a1) and/or a hydrolyzable vinyl monomer (a2) and an internal crosslinking agent (b), and composite particles (C), obtained by applying a hydrophilic substance (B) on a portion or the whole of the surface of each crosslinked polymer (A2) particle comprising, as essential constitutive units, a water-soluble vinyl monomer (a1) and/or a hydrolyzable vinyl monomer (a2) and an internal crosslinking agent (b) or by impregnating the crosslinked polymer (A2) particle with the hydrophilic substance (B). The absorbent resin particles are characterized by having such a structure that a portion or the whole of the composite particle (C) is included in the absorbent resin particle (D). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to absorbent resin particles and absorbent articles.

In order to improve the liquid absorption rate of the absorbent resin particles, it has been proposed to increase the surface area of the absorbent resin particles and increase the contact surface with the liquid {for example, by making fine silicon dioxide particles coalesced Granulated absorbent resin particles (Patent Document 1), absorbent resin particles having air bubbles introduced therein (Patent Document 2)}. Further, an absorbent resin particle in which an interface is formed by a hydrophobic material and an apparent surface area is increased is also known (Patent Document 3).
Japanese Patent Laid-Open No. 8-253597 JP 2002-212331 A JP 2005-97569 A

In the conventional absorbent resin particles having an increased surface area, the absorbent resin particles may absorb less under load than the absorbent resin particles having the same particle size without increasing the surface area. There is a problem that the absorption speed of the liquid is slow. And when this absorbent resin particle is applied to an absorbent article, there exists a problem that the dry feeling of the surface of an absorbent article may worsen.
That is, an object of the present invention is to provide absorbent resin particles having a high absorption amount under load and a high absorption rate of liquid under load, and an absorbent article having a high dry feeling on the surface of the absorbent article. It is to be.

The inventor of the present invention has arrived at the present invention as a result of intensive studies to achieve the above object.
That is, the characteristic of the absorbent resin particles of the present invention is that the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the crosslinked polymer (A1) having the internal crosslinking agent (b) as essential constituent units. When,
Water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) and hydrophilic polymer (A2) on part or all of the surface of crosslinked polymer (A2) particles having internal crosslinking agent (b) as essential constituent units B) an absorbent resin particle (D) containing or coated with or impregnated composite particles (C), wherein part or all of the composite particles (C) are contained inside the absorbent resin particles (D). The gist is that it has a structure to include.

A feature of the method for producing absorbent resin particles of the present invention is that a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) and a cross-linked polymer (A2) having an internal cross-linking agent (b) as essential constituent units. ) Composite particles (C) in which a part or all of the surface of the particles is coated or impregnated with a hydrophilic substance (B);
The water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the crosslinked polymer (A1) having the internal crosslinking agent (b) as essential constituent units are mixed and kneaded to obtain absorbent resin particles (D Or a part of the surface of the crosslinked polymer (A2) particles having the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the internal crosslinking agent (b) as essential constituent units, or Essential composition of water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) and internal cross-linking agent (b) in the presence of composite particles (C) that are all coated or impregnated with hydrophilic substance (B) The gist is that it includes a step of polymerizing as a unit to obtain a crosslinked polymer (A1) and obtaining absorbent resin particles (D).

  The absorptive resin particles of the present invention exhibit the effects that the absorption amount under load is high and the absorption rate of the liquid under load is fast. Therefore, when this absorbent resin particle is applied to an absorbent article, the effect of being excellent in the dry feeling of the surface of an absorbent article is brought about.

  The method for producing absorbent resin particles of the present invention can easily produce absorbent resin particles having a high absorption amount under load and a high liquid absorption rate under load. Therefore, when the absorbent resin particles produced by the production method of the present invention are applied to an absorbent article, the effect of being excellent in the dry feeling of the surface of the absorbent article is brought about.

  The crosslinked polymer (A1) and the crosslinked polymer (A2) include a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) and an internal crosslinking agent (b) as essential constituent units. If it is, there will be no restriction | limiting in particular, Well-known thing {For example, the polymer etc. of the following (1)-(16)}] can be used as it is. Note that “water-soluble” means a property of dissolving at least 100 g in 100 g of water at 25 ° C. The term “hydrolyzable” means the property of being hydrolyzed by the action of water at 50 ° C. and, if necessary, the catalyst (acid or base, etc.) to make it water-soluble (hydrolysis is still a vinyl monomer, as a crosslinked polymer) It may be from.)

(1) A starch-acrylic acid (salt) graft-crosslinked copolymer described in JP-B-53-46199 or JP-B-53-46200.
(2) Crosslinked polyacrylic acid (salt) obtained by aqueous solution polymerization (adiabatic polymerization, thin film polymerization, spray polymerization, etc.) described in JP-A-55-133413.
(3) Cross-linked polyacrylic acid (salt) obtained by reverse phase suspension polymerization described in JP-B-54-30710, JP-A-56-26909, or JP-A-11-5808.
(4) A saponified product of a copolymer of a vinyl ester and an unsaturated carboxylic acid or a derivative thereof described in JP-A-52-14689 or JP-A-52-27455.
(5) A copolymer of acrylic acid (salt) and a sulfo (sulfonate) group-containing monomer described in JP-A-58-2312 or JP-A-61-36309.

(6) A saponified product of crosslinked isobutylene-maleic anhydride copolymer described in US Pat. No. 4,389,513.
(7) A starch-acrylonitrile copolymer hydrolyzate described in JP-A-46-43995.
(8) Crosslinked carboxymethylcellulose as described in US Pat. No. 4,650,716 and the like.
(9) A polyalkylene (ethylene, propylene, etc.) glycol cross-linked product as described in the latest trend of polymer gels (CMC Publishing Co., Ltd., published in 2004).
(10) A crosslinked polyvinyl alcohol as described in the latest trend of polymer gels (CMC Publishing, published in 2004).
(11) A starch radiation cross-linked product described in JP-A-2003-48997.
(12) A carboxyl group-containing crosslinked cellulose described in JP-A-9-85080.
(13) A polyamino acid radiation cross-linked product described in JP-A-10-251402.
(14) The crosslinked polyaspartic acid described in JP-A-2002-179770.
(15) A polyvalent metal ion cross-linked product of a polysaccharide described in JP-A No. 2001-120992.

(16) JP-A-2003-057422, JP-A-2003-082250, JP-A-2003-165683, JP-A-2003-176421, JP-A-2003-183528, JP-A-2003-192732 JP, 2003-225565, JP 2003-238696, JP 2003-335970, JP 2004-009673, JP 2004-121400, JP 2004-123835, JP JP 2005-075982, JP 2005-095759, JP 2005-186015, JP 2005-186016, JP 2006-110545, JP 2006-122737, JP 2006. -131767, JP 2006 160774, JP 2006-206777, JP 2006-219661, JP-performance water-absorbent resin described in 2007-069161, etc. {crosslinked polyacrylic acid (salt)}.

Among these, (1), (2), (3) and (16) are preferable, (1), (2) and (16) are more preferable, and (2) and (16) are particularly preferable.
The crosslinked polymer (A2) may be surface-crosslinked, but is preferably not surface-crosslinked.

  The shape of the crosslinked polymer (A2) particles is not limited as long as it is particulate, but is preferably indefinite (crushed), true spherical, plate-like, and rod-like, and more preferably indefinite (crushed), true spherical or A plate shape, particularly preferably an irregular shape (crushed shape) or a plate shape.

  The particle size range of the crosslinked polymer (A2) particles can be adjusted by a known method (sieving, sieving after pulverization, etc.) and the like.

  The weight average particle diameter (μm) of the crosslinked polymer (A2) particles is preferably 1 to 800, more preferably 10 to 350, particularly preferably 20 to 180, and most preferably 30 to 100. Within this range, the moisture resistance of the absorbent article is further improved.

  The weight average particle size is measured by measuring the particle size distribution of the measurement sample, and plotting the relationship between the cumulative content and the particle size on logarithmic probability paper {horizontal axis: particle size, vertical axis: cumulative content (wt%)}. The particle size corresponding to a cumulative content of 50% by weight is obtained. The particle size distribution is measured in accordance with JIS Z8815-1994. For example, sieves with an inner diameter of 150 mm and a depth of 45 mm {openings: 710 μm, 500 μm, 300 μm, 150 μm and 106 μm} are used with a narrow opening sieve. Overlay, put 50 g of measurement sample on top of 710 μm sieve with widest opening, sieve for 10 minutes with sieve shaker, measure weight of measurement sample remaining on each sieve, It is measured by determining the weight percent of the measurement sample remaining on each sieve based on the weight of the measurement sample.

As the hydrophilic substance (B), a solid or liquid that can be at least partially dissolved in water at 25 ° C. can be used.
The solubility (g / ml) of the hydrophilic substance (B) in water at 25 ° C. is preferably at least 0.001, more preferably 0.01 to 10, particularly preferably 0.1 to 1. Within this range, the moisture resistance of the absorbent article is further improved.

  When the hydrophilic substance (B) is a liquid, the hydrophilic substance (B) has a viscosity (mPa · s) at 25 ° C. of preferably 10 to 4000, more preferably 100 to 3000, and particularly preferably 500 to 2000. Within this range, the surface dryness of the absorbent article is further improved.

  10-20 are preferable, as for the HLB value of a hydrophilic substance (B), More preferably, it is 12-18, Most preferably, it is 13-17. Within this range, the surface dry feeling of the absorbent article is further improved. The HLB value is from Davis's HLB (Takehiko Fujimoto, “Introduction to New Surfactant”, Sanyo Kasei Kogyo Co., Ltd., August 1992, 3rd edition, page 132; New Introduction to Surface Active Agents "Copyright 1985, SANYO CHEMICAL INDUSTRIES, LTD, page 132).

Hydrophilic solids include inorganic solids and organic solids.
As the inorganic solid, metal salts (sodium hydrogen carbonate, sodium carbonate, sodium hydrogen sulfite, sodium sulfite, sodium hydrogen sulfate, sodium sulfate, potassium hydrogen carbonate, potassium carbonate, calcium carbonate, calcium sulfate and the like) can be used.

  Examples of organic solids include natural polymers {saccharides (such as sucrose and glucose)}, synthetic polymers (such as polyvinyl alcohol, vinyl acetate, poly (meth) acrylic acid (uncrosslinked), polyethylene glycol, and polypropylene glycol). It is done.

  Examples of the hydrophilic liquid include the above-described synthetic polymer oligomers (ethylene glycol, ethylene glycol oligomers (n = 2 to 6), propylene glycol and propylene glycol oligomers (n = 2 to 6), and the like). .

  Of these hydrophilic substances, hydrophilic solids are preferred from the viewpoint of the absorption rate of the liquid under load, more preferably organic solids, particularly preferably polyvinyl alcohol, poly (meth) acrylic acid and polypropylene glycol, and then Polyvinyl alcohol and poly (meth) acrylic acid are preferred, and poly (meth) acrylic acid is most preferred.

  When the composite particles (C) are obtained by coating or impregnating the hydrophilic polymer (B) on part or all of the surface of the crosslinked polymer (A2) particles, the hydrophilic polymer (B) is dissolved or emulsified in a solvent. -It can be used as a liquid by dispersing or heating to the melting point or higher of the hydrophilic substance (B).

Solvents include water and volatile organic solvents. The volatile organic solvent preferably has a vapor pressure (Pa) at 20 ° C. of 0.13 to 5.3, more preferably 0.15 to 4.5, particularly from the viewpoint of easy removal. It is preferably 0.23 to 3.8. Examples of volatile organic solvents include alcohols having 1 to 3 carbon atoms (such as methanol, ethanol and isopropyl alcohol), hydrocarbons having 5 to 8 carbon atoms (such as pentane, hexane, cyclohexane and toluene), and ethers having 2 to 4 carbon atoms. (Dimethyl ether, diethyl ether, tetrahydrofuran, etc.), C3-C4 ketones (acetone, methyl ethyl ketone, etc.), C3-C5 esters (ethyl formate, ethyl acetate, isopropyl acetate, diethyl carbonate, etc.) and the like. . When water and / or a volatile organic solvent is used, the content (% by weight) thereof is preferably 1 to 900, more preferably 5 to 700, particularly preferably based on the weight of the hydrophilic substance (B). Is 10-400. When water and a volatile organic solvent are used, the amount of water used (% by weight) is preferably 50 to 98, more preferably 60 to 95, particularly preferably 70, based on the weight of water and the volatile organic solvent. ~ 90.
When a solvent is used for coating or impregnation, it is preferable to distill off the solvent.

  “Coating or impregnating the hydrophilic substance (B) on part or all of the surface of the crosslinked polymer (A2) particles” means that the hydrophilic substance (B) is present on the surface of the crosslinked polymer (A2) particles. For example, it means that it may not be the entire surface, and it may exist inside the surface. That is, it means that the hydrophilic substance (B) is present on at least a part of the surface of the crosslinked polymer (A2) particles.

In order to coat or impregnate the hydrophilic substance (B) on part or all of the surface of the crosslinked polymer (A2) particles, the liquid is sprayed on the crosslinked polymer (A2) particles, or the crosslinked polymer is applied to the liquid. (A2) This can be achieved by dipping the particles. The crosslinked polymer (A2) particles may be contacted with a solid hydrophilic substance (B) or an emulsified dispersion of (B), and then heated or heated to the melting point of (B) or coated or impregnated. .
Examples of the mixing device applicable to spraying, dipping, or contact include a nauter mixer and a turbulizer.

  The content (% by weight) of the hydrophilic substance (B) is preferably 0.0001 to 10, more preferably 0.005 to 5, particularly preferably 0.07 to 5, based on the weight of the composite particles (C). 3, most preferably 0.1-1. Within this range, the surface dry feeling of the absorbent article is further improved.

  The content (% by weight) of the crosslinked polymer (A2) particles is preferably from 1 to 60, more preferably from 10 to 50, and particularly preferably from 20 to 40, based on the weight of the crosslinked polymer (A1). Within this range, the surface dryness of the absorbent article is further improved.

  The absorptive resin particles of the present invention have a structure including a part or all of the composite particles (C) inside. The structure including all of the composite particles (C) inside means a state in which the composite particles (C) are completely embedded in the absorbent resin particles. On the other hand, the structure containing a part of the composite particles (C) inside means a state in which at least a part of the composite particles (C) is in contact with the cross-linked polymer (A1) and does not fall off from the cross-linked polymer (A1). However, the composite particles (C) and the cross-linked polymer (A1) are not in separate states.

  The absorbent resin particles of the present invention preferably further contain a diffusion penetrant (E). When the diffusion penetrant (E) is contained, the absorption performance (absorption amount and absorption rate) under load is further improved. The diffusion penetrant (E) is an additive for improving the diffusibility and penetrability of the liquid inside the absorbent resin particles, and is a conventionally known surfactant or the like (for example, Patent Document 3, “Water-soluble high Surfactant described in “Molecular Technology” published by CMC Publishing in May 2000 and “Applied Technology of Surfactant” published by CMC Publishing in December 2002 can be used.

  When the crosslinked polymer (A1) and / or the crosslinked polymer (A2) is obtained by aqueous solution polymerization, among the surfactants, anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric ones. Surfactants can be used. Of these, anionic surfactants and nonionic surfactants are preferred from the viewpoint of the surface dry feeling of the absorbent article, and more preferred are alkyl (ether) sulfate esters, alkyl (or alkylphenyl) sulfonates. Alkyl (ether) phosphate ester salts, fatty acid salts and polyhydric alcohol fatty acid esters, particularly preferably sodium lauryl sulfate, sodium lauryl phosphate, sodium dodecylbenzenesulfonate, sodium diethylhexylsulfosuccinate, sodium lauryl phosphate, laurin Sodium sorbate, sorbitan lauric acid (mono / di) ester, sorbitan palmitic acid (mono / di) ester, sorbitan stearic acid (mono / di) ester, sorbitan oleic acid (mono / di) ester and sorbitan palm (Mono / di) ester, sorbitan laurate (mono / di) esters, most preferably sodium dodecyl benzene sulfonate, hexyl sodium sulfosuccinate to diethyl.

  When the crosslinked polymer (A1) and / or the crosslinked polymer (A2) is obtained by emulsion polymerization or reverse phase suspension polymerization, the diffusion penetrant (E) may be emulsion polymerization or reverse phase suspension polymerization. The same surfactant as the surfactant used (emulsifier / dispersant) is not preferred. This is because even if such a same surfactant is used as the diffusion penetrant (E), it is considered that the diffusibility and penetrability of the liquid are unlikely to be improved inside the absorbent resin particles. In this case, an anionic surfactant and a cationic surfactant that are different from the surfactant used in emulsion polymerization or reverse phase suspension polymerization are preferred, and a different anionic surfactant is more preferred. The different anionic surfactants are preferably the same as those exemplified in the aqueous solution polymerization.

As an HLB value of a diffusion penetrant (E), 6-18 are preferable, More preferably, it is 7-15, Most preferably, it is 8-12. Within this range, the surface dry feeling of the absorbent article is further improved.
The diffusion penetrant (E) can also be used in a form dissolved and / or emulsified in a solvent.

  When the diffusion penetrant (E) is contained, the content (% by weight) of (E) is preferably 0.001-1 based on the weight of the crosslinked polymer (A1), more preferably 0.01- 0.5, particularly preferably 0.05 to 0.1. Within this range, the surface dryness when applied to an absorbent article is further improved.

  When the diffusion penetrant (E) is contained, it is preferably present inside the absorbent resin particles, and more preferably present on the surface (interface) of the crosslinked polymer (A2) particles.

  The absorbent resin particles are preferably (1) a composite gel (C), a crosslinked polymer (A1) {a hydrogel containing a crosslinked polymer (A1) and water. Are mixed and kneaded to obtain absorbent resin particles, or (2) a water-soluble vinyl monomer (a1) and / or a vinyl monomer that becomes (a1) by hydrolysis in the presence of the composite particles (C) ( It is produced by a method in which a2) and the internal crosslinking agent (b) are polymerized as essential constituent units to obtain a crosslinked polymer (A1) and to obtain absorbent resin particles.

  The method of mixing and kneading the crosslinked polymer (A1) and the composite particles (C) is such that the composite particles (C) are present inside the crosslinked polymer (A1) {preferably the crosslinked polymer (A1) As long as the composite particles (C) are buried in the interior of the material, there is no limitation. However, the composite particle (C) contains not the cross-linked polymer (A1) {aggregate of dried bodies} but a hydrogel of the cross-linked polymer (A1) {cross-linked polymer (A1) and water. } Or (A1) is preferably mixed with the polymerization liquid, and more preferably mixed with the hydrogel (A1). In addition, it is preferable to mix uniformly so that mixing may be carried out.

  The timing for mixing and kneading the composite particles (C) and the crosslinked polymer (A1) is not particularly limited, but during the polymerization step of the crosslinked polymer (A1), immediately after the polymerization step, during pulverization (mincing) of the hydrogel. And during the drying of the hydrogel. Among these, from the viewpoint of surface dryness when applied to an absorbent article, it is preferable immediately after the polymerization step of the cross-linked polymer (A1) and during the crushed (minced) step of the hydrated gel, more preferably crushed of the hydrated gel. (Minch) In process.

  As the mixing / kneading device, when mixing and kneading during pulverization (mincing) of the hydrogel, ordinary devices such as a Bex mill, rubber chopper, pharma mill, mincing machine, impact pulverizer, and roll pulverizer can be used. . When mixing and kneading in the polymerization solution, a device having a relatively high stirring force such as a homomixer or a biomixer can be used. Moreover, when mixing and kneading in the course of drying the hydrogel, a kneading apparatus such as an SV mixer can also be used.

  In the case of containing the diffusion penetrant (E), as a method for containing the diffusion penetrant (E), (1) after mixing the crosslinked polymer (A2) particles and the diffusion penetrant (E), A method of preparing composite particles (C) by coating or impregnating the surface with a hydrophilic substance (B); (2) a crosslinked polymer (A1) and / or composite particles (C) and a diffusion penetrant (E). A method of mixing and kneading these after mixing; (3) A method of mixing and kneading the cross-linked polymer (A1), composite particles (C) and diffusion penetrant (E); (4) Composite particles (C) The method of mixing immediately after the superposition | polymerization process of the crosslinked polymer (A1) performed in presence of this, and the crushing (mincing) process of a hydrous gel etc. are included.

  As an apparatus containing the diffusion penetrant (E), an apparatus used for mixing and kneading the composite particles (C) and the crosslinked polymer (A1) can be used.

  When the absorbent resin particles obtained by mixing and kneading the composite particles (C) and the cross-linked polymer (A1) or polymerizing in the presence of the composite particles (C) contain water (in the case of hydrogel particles) If necessary, the hydrogel particles can be chopped (crushed) by a known method or the like. The size (longest diameter) of the hydrogel particles after chopping (crushing) is preferably 50 μm to 10 cm, more preferably 100 μm to 2 cm, and particularly preferably 1 mm to 1 cm. Within this range, the drying property in the drying process is further improved.

  The absorbent resin particles can be pulverized and / or adjusted in particle size by a known method. When the absorbent resin particles contain a solvent, it is preferable to pulverize and / or adjust the particle size after the solvent is distilled off (dried).

  The weight average particle diameter (μm) of the absorbent resin particles is preferably 100 to 800, more preferably 200 to 500, and particularly preferably 300 to 400. Within this range, handling properties (powder fluidity of absorbent resin particles, etc.) are further improved. In addition, a weight average particle diameter can be measured like the case of a crosslinked polymer (A2).

  The absorbent resin particles preferably have a smaller content of fine particles from the viewpoint of absorption performance. The content of fine particles of 150 μm or less (preferably 106 μm) or less in the total particles of the absorbent resin particles is preferably 3% by weight or less, more preferably 1% by weight or less. The content of the fine particles can be determined using a plot created when determining the above weight average particle diameter.

  The shape of the absorbent resin particles is not particularly limited, and examples thereof include an irregularly crushed shape, a flake shape, a pearl shape, and a rice grain shape. Among these, from the viewpoint of good entanglement with a fibrous material when applied to a paper diaper and the like and no fear of dropping off from the fibrous material, an amorphous crushed shape is preferable.

  The absorbent resin particles can be surface-crosslinked by a known method or the like as necessary.

The water content (% by weight) of the absorbent resin particles of the present invention is preferably from 1 to 15, more preferably from 2 to 12, particularly from the viewpoint of workability, texture, moisture resistance, etc. when applied to absorbent articles. Preferably it is 4-10. Within this range, the absorbent resin particles are prevented from being destroyed by impact, and workability and the like are further improved.
The moisture content is not determined only by the drying process, but is adjusted by a surface cross-linking process, a hydration process, and the like performed as necessary. The water content is determined from the weight loss rate before and after drying at 120 ± 5 ° C. for 30 minutes.

  A known additive can be added to the absorbent resin particles of the present invention at any stage as necessary. Examples of additives that can be used include antiseptics, fungicides, antibacterial agents, antioxidants, ultraviolet absorbers, colorants, fragrances, deodorants, and organic fibrous materials.

When the additive is added, the total additive amount (% by weight) of the additive varies depending on the use, but is preferably 10 ^{−6 to} 20 and more preferably 10 ⁻⁵ to 10 based on the weight of the absorbent resin particles. Especially preferably, it is 10 ^<-4 > -5. Within this range, an antibacterial action and the like can be imparted without reducing the absorption performance of the absorbent resin particles.

  The absorbent resin particles of the present invention can be manufactured to various absorbents by a known method to produce an absorbent article having excellent absorption performance.

  The amount (% by weight) of the absorbent resin particles of the present invention to the absorber can be variously changed according to the type and size of the absorber and the target absorption performance, but the absorbent resin particles and the fibrous material 30-95 are preferable based on the total weight of, more preferably 40-94, particularly preferably 50-93. Within this range, the absorbent capacity of the resulting absorber is further improved.

  The absorbent body using the absorbent resin particles of the present invention can be used even if it absorbs liquid {absorbed liquid (body fluid such as sweat, urine and blood, and water such as seawater, groundwater and muddy water)}. Therefore, when applied to sanitary goods such as disposable diapers and sanitary napkins, it exhibits not only excellent absorption performance but also excellent characteristics that the liquid to be absorbed is difficult to reverse even under pressure.

  As an absorbent article, an absorbent article provided with an absorber, a liquid permeable sheet, and a breathable back sheet is preferable, and more preferably an absorbent article as a sanitary article. Hygiene products include paper diapers (children's disposable diapers and adult disposable diapers, etc.), napkins (such as sanitary napkins), paper towels, pads (such as incontinence pads and surgical underpads), and pet sheets (pet urine absorbing sheets). Etc. Of these hygiene articles, they are more suitable for disposable diapers. Further, even among paper diapers, the surface dryness value measured by the SDME method is optimal for paper diapers requiring a value of 50% or more, more preferably 55% or more.

<Surface dryness value by SDME method>
The surface dryness value by the SDME method is measured by the following procedure using an SDME (Surface Dryness Measurement Equipment) tester (manufactured by WK system).
A paper diaper (artificial urine enough to cover the paper diaper (0.03% by weight of calcium chloride, 0.08% by weight of magnesium sulfate, 0.8% by weight of sodium chloride and 99.% of ion-exchanged water). 09% by weight) and left on top for 60 minutes to set a 0% dryness value, and then set the detector of the SDME tester to a dry paper diaper (paper diaper was heated at 80 ° C. for 2 hours) Set 100% dryness and calibrate the SDME tester.

  Next, a metal ring (inner diameter 70 mm, outer diameter 80 mm length 50 mm, weight 300 g) is set at the center of the paper diaper to be measured, and 80 ml of artificial urine is injected. Immediately after injection, the metal ring is removed, and an SDME detector is set in contact with the paper diaper at the center of the paper diaper, and measurement is started. The value 3 minutes after the start of measurement is taken as the surface dryness value by SDME.

  The absorbent resin particles of the present invention are not only used for sanitary products as described above, but also pet urine absorbents, urine gelling agents for portable toilets, freshness preservation agents such as fruits and vegetables, drip absorbents for meat and seafood, cold insulation agents, It is also useful for various applications such as disposable body warmers, battery gelling agents, water retention agents such as plants and soil, anti-condensation agents, water-stopping materials and packing materials, and artificial snow.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Hereinafter, unless otherwise specified, parts indicate parts by weight and% indicates% by weight.

<Production Example 1>
In a glass reaction vessel, 77 parts of sodium acrylate, 22.85 parts of acrylic acid, 0.15 part of N, N′-methylenebisacrylamide, 299.54 parts of deionized water, and 0.25 parts of dichlorotris (triphenylphosphine) ruthenium. 001 parts were charged, and the temperature of the contents was kept at 3 ° C. while stirring and mixing. Nitrogen was introduced into the contents to make the dissolved oxygen amount 1 ppm or less, 0.3 part of 1% aqueous solution of hydrogen peroxide, 0.8 part of 0.2% aqueous solution of ascorbic acid and 2,2′-azobisamidinopropane By adding and mixing 0.8 parts of a 2% aqueous solution of dihydrochloride, the polymerization is started, and after the reaction solution reaches 80 ° C., it is polymerized at a polymerization temperature of 80 ± 2 ° C. for about 5 hours, thereby producing a crosslinked polymer. A hydrous gel (1) was obtained. The water content (120 ± 5 ° C. × 30 minutes) was 75%.

  400 parts of hydrous gel (1) was kneaded at 25 ° C. for 5 minutes with a mincing machine (hole diameter of eye plate: 6 mm, 12VR-400K manufactured by Iizuka Kogyo Co., Ltd.), and then the conditions of 135 ° C. and wind speed of 2.0 m / sec. And dried with a vent type band dryer. This dried product is pulverized with a commercially available juicer mixer (Matsushita Electric Industrial Co., Ltd., Fiber Mixer MX-X57), adjusted to a particle size of 250 to 106 μm using a sieve with openings of 250 and 106 μm, and a crosslinked polymer ( a2-1) Particles were obtained. The weight average particle diameter of the crosslinked polymer (a2-1) particles was 180 μm.

<Production Example 2>
Crosslinked polymer (a2-2) particles were obtained in the same manner as in Production Example 1, except that “the sieves with openings of 250 and 106 μm” were changed to “screens with openings of 63 and 25 μm”. The weight average particle diameter of the crosslinked polymer (a2-2) particles was 30 μm.

<Production Example 3>
Crosslinked polymer (a2-3) particles are obtained in the same manner as in Production Example 1, except that the amount of N, N′-methylenebisacrylamide used is changed from “0.15 parts” to “0.3 parts”. It was. The weight average particle diameter of the crosslinked polymer (a2-3) particles was 180 μm.

<Production Example 4>
The amount of N, N′-methylenebisacrylamide used was changed from “0.15 parts” to “0.3 parts”, “screening with openings of 250 and 106 μm” and “screening with openings of 150 and 45 μm”. A crosslinked polymer (a2-4) particle was obtained in the same manner as in Production Example 1 except that The weight average particle diameter of the crosslinked polymer (a2-4) particles was 100 μm.

<Production Example 5>
145.4 parts of acrylic acid was diluted with 9.4 parts of water and neutralized by adding 242.3 parts of 25% aqueous sodium hydroxide while cooling to 30-20 ° C. To this solution, 0.09 part of ethylene glycol diglycidyl ether, 0.0146 part of sodium hypophosphite monohydrate and 0.0727 part of potassium persulfate were added and dissolved, and a biomixer (Nippon Seiki Co., Ltd.) was added at 25 ° C. A monomer aqueous solution was obtained by stirring and dispersing for 2 minutes using ABM-2 manufactured by the company.

  Next, 624 parts of cyclohexane was placed in a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas introduction tube, and polyoxyethylene octylphenyl ether phosphate (Daiichi Kogyo Seiyaku Co., Ltd., Commodity) (Name: Prisurf A210G) 1.56 parts was added and dissolved, and then purged with nitrogen while stirring, and the temperature was raised to 70 ° C. Then, the monomer aqueous solution was dropped at 6.6 parts / min for 6 minutes while being kept at 70 ° C. and held at 75 ° C. for 15 minutes, and then the remaining monomer aqueous solution was kept at 6.6 parts / min for 54 minutes. It was dripped. Then, after aging at 75 ° C. for 30 minutes, the water content of the resin is about 20% by azeotroping water with cyclohexane (infrared moisture meter: FD-100 type, manufactured by Kett, measured at 180 ° C. for 20 minutes). Removed until When the stirring was stopped after cooling to 30 ° C., the resin particles settled, the resin particles and the cyclohexane layer were separated by decantation, filtered and dried under reduced pressure at 80 ° C., and sieved with openings of 250 and 106 μm. By using it and adjusting to a particle size of 250 to 106 μm, crosslinked polymer (a2-5) particles were obtained. The weight average particle diameter of the crosslinked polymer (a2-5) particles was 180 μm.

<Production Example 6>
The cross-linked polymer (a2−2) was prepared in the same manner as in Production Example 5 except that “the sieve with openings of 250 and 106 μm” was changed to “the sieve with openings of 150 and 45 μm” and adjusted to a particle size of 250 to 106 μm. 6) Particles were obtained. The weight average particle diameter of the crosslinked polymer (a2-6) particles was 100 μm.

<Production Example 7>
In the same manner as in Production Example 5, except that “1.56 parts of polyoxyethylene octylphenyl ether phosphate” was changed to “2.34 parts of polyoxyethylene octylphenyl ether phosphate”, a crosslinked polymer ( a2-7) Particles were obtained. The weight average particle diameter of the crosslinked polymer (a2-7) particles was 180 μm.

<Production Example 8>
To 5 parts of the crosslinked polymer (a2-1) particles obtained in Production Example 1, 0.005 part of hydrophilic substance (b1) {polyethylene glycol (Sanyo Chemical Industries, Ltd. product: PEG-2000; HLB10) is added to methanol 10 10 parts is added, and the mixture is stirred for 2 minutes with a biomixer (ABM-2 type, manufactured by Nippon Seiki Co., Ltd.) at 25 ° C. and then dried at 60 ° C. for 1 hour to obtain composite particles (c1 )

<Production Example 9>
To 5 parts of the crosslinked polymer (a2-2) particles obtained in Production Example 2, 10.005 parts of the hydrophilic substance (b1) is added, and the biomixer (ABM-2 type manufactured by Nippon Seiki Co., Ltd.) is added at 25 ° C. The mixture was stirred for 2 minutes and then dried at 60 ° C. for 1 hour to obtain composite particles (c2).

<Production Example 10>
To 5 parts of the crosslinked polymer (a2-3) particles obtained in Production Example 3, 0.05 part of hydrophilic substance (b2) {polyoxyethylene alkyl ether sodium sulfate (Sanyo Chemical Industries, Ltd. product: Sandet EN; HLB17) 10.05 parts of a solution prepared by dissolving 10 parts of methanol in methanol}, and stirring for 2 minutes at 25 ° C. with a biomixer (ABM-2 type manufactured by Nippon Seiki Co., Ltd.), followed by drying at 60 ° C. for 1 hour. And composite particles (c3) were obtained.

<Production Example 11>
10.05 parts of hydrophilic substance (b2) is added to 5 parts of the crosslinked polymer (a2-4) particles obtained in Production Example 4, and the biomixer (ABM-2 type, manufactured by Nippon Seiki Co., Ltd.) is added at 25 ° C. The mixture was stirred for 2 minutes and then dried at 60 ° C. for 1 hour to obtain composite particles (c4).

<Production Example 12>
While stirring 50 parts of the crosslinked polymer (a2-5) particles obtained in Production Example 5 at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), the hydrophilic substance (b3) {high-purity aqueous potassium hydroxide solution (Tsurumi Soda Co., Ltd. product: CLEARCUT-S; HLB15, concentration 48%) 2 parts were added while being sprayed and mixed, and then dried at 60 ° C. for 1 hour to obtain composite particles (c5).

<Production Example 13>
“Crosslinked polymer (a2-5) particles obtained in Production Example 5” was changed to “Crosslinked polymer (a2-6) particles obtained in Production Example 6”, and “Hydrophilic substance (b3)” Except for changing to "Hydrophilic substance (b4) {potassium aluminum sulfate (Takasugi Pharmaceutical Co., Ltd .: Alum, HLB14) 0.5 part in 5 parts of water}", in the same manner as in Production Example 12, Composite particles (c6) were obtained.

<Production Example 14>
To 5 parts of the crosslinked polymer (a2-7) particles obtained in Production Example 7, 10.05 parts of the hydrophilic substance (b1) is added and added to a biomixer (ABM-2 type manufactured by Nippon Seiki Co., Ltd.) at 25 ° C. The mixture was stirred for 2 minutes and then dried at 60 ° C. for 1 hour to obtain composite particles (c7).

<Example 1>
400 parts hydrogel (1) obtained in Production Example 1, 40 parts of composite particles (c1) obtained in Production Example 8 and diffusion penetrant (e1) {Sanyo Kasei Kogyo Anionic Surfactant: Sanmorin OT70; HLB17: “Sanmorin” is a registered trademark of the same company. } After 0.4 parts were kneaded at 25 ° C. for 5 minutes with a minced machine (hole diameter of the countersunk plate: 6 mm, manufactured by Iizuka Kogyo Co., Ltd., 12VR-400K), It dried with the ventilation type band dryer, and obtained the dried body. The dried product was pulverized with a commercially available juicer mixer {Matsushita Electric Industrial Co., Ltd., Fiber Mixer MX-X57}, adjusted to a particle size of 850 to 106 μm using a sieve with an opening of 850 and 106 μm, and then 100 parts of this dried product was mixed. Spray two parts of ethylene glycol diglycidyl ether 10% water / methanol mixed solution (weight ratio of water / methanol = 70/30) while stirring at high speed (high speed stirring turbulizer manufactured by Hosokawa Micron: 2000 rpm). Then, the mixture was left to stand at 140 ° C. for 30 minutes to cross-link the surface to obtain the absorbent resin particles (1) of the present invention. The weight average particle diameter of the absorbent resin particles (1) was 375 μm.

<Example 2>
“Composite particle (c1)” was changed to “Composite particle (c2)”, “Diffusion penetrant (e1) 0.4 part” was changed to “Diffusion penetrant (e1) 0.8 part”, In addition, the absorbent resin particles of the present invention were the same as in Example 1 except that the sieves having an aperture of 850 and 106 μm were changed to the sieves having an aperture of 500 and 106 μm and adjusted to a particle size of 500 to 106 μm. (2) was obtained. The weight average particle diameter of the absorbent resin particles (2) was 300 μm.

<Example 3>
The absorbent resin of the present invention was the same as in Example 1 except that “composite particles (c1)” was changed to “composite particles (c3)” and that “diffusion penetrant (e1)” was not used. Particles (3) were obtained. The weight average particle diameter of the absorbent resin particles (3) was 377 μm.

<Example 4>
Absorbent resin particles (4) of the present invention were obtained in the same manner as in Example 1 except that “composite particles (c1)” were changed to “composite particles (c4)”. The weight average particle diameter of the absorbent resin particles (4) was 375 μm.

<Example 5>
The absorbent resin of the present invention was the same as in Example 1 except that “composite particles (c1)” was changed to “composite particles (c5)” and that “diffusion penetrant (e1)” was not used. Particles (5) were obtained. The weight average particle diameter of the absorbent resin particles (5) was 376 μm.

<Example 6>
“Composite particle (c1)” was changed to “composite particle (c6)”, and “diffusion penetrant (e1)” was changed to “diffusion penetrant (e2) {manufactured by Sanyo Chemical Industries, Ltd .: Sannonic SS-70; HLB12, a nonionic surfactant: “Sannonic” is a registered trademark of the same company. }] Was obtained in the same manner as in Example 1 except that the absorbent resin particles (6) of the present invention were obtained. The weight average particle diameter of the absorbent resin particles (6) was 375 μm.

<Example 7>
“Diffusion penetrant (e1)” is “Diffusion penetrant (e3) {manufactured by Sanyo Chemical Industries, Ltd .: NAROACTY ID50; HLB10, nonionic surfactant:“ NAROACTY ”is a registered trademark of the same company. }] Was obtained in the same manner as in Example 1 except that the absorbent resin particles (7) of the present invention were obtained. The weight average particle diameter of the absorbent resin particles (7) was 374 μm.

<Example 8>
“Composite particle (c1)” was changed to “composite particle (c2)”, “Diffusion penetrant (e1)” was changed to “Diffusion penetrant (e4) {manufactured by Sanyo Chemical Industries, Ltd .: NAROACTY ID40; HLB8, Absorbent resin particles (8) of the present invention were obtained in the same manner as in Example 1 except that it was changed to "Nonionic surfactant}". The weight average particle diameter of the absorbent resin particles (8) was 375 μm.

<Example 9>
Absorbent resin particles (9) of the present invention were obtained in the same manner as in Example 1, except that the composite particles (c1) were changed from “40 parts” to “60 parts”. The weight average particle diameter of the absorbent resin particles (9) was 375 μm.

<Example 10>
Example 1 except that the composite particles (c1) were changed from “40 parts” to “10 parts” and the diffusion penetrant (e1) was changed from “0.4 parts” to “0.14 parts”. Similarly, the absorbent resin particle (10) of this invention was obtained. The weight average particle diameter of the absorbent resin particles (10) was 374 μm.

<Example 11>
Example except that “composite particle (c1) 40 parts” was changed to “composite particle (c7) 20 parts” and “diffusion penetrant (e1)” was changed to “diffusion penetrant (e3)” In the same manner as in No. 1, absorbent resin particles (11) of the present invention were obtained. The weight average particle diameter of the absorbent resin particles (11) was 375 μm.

<Example 12>
In a glass reaction vessel, 77 parts of sodium acrylate, 22.85 parts of acrylic acid, 0.15 part of N, N′-methylenebisacrylamide, 299.54 parts of deionized water, 0. 7 parts of dichlorotris (triphenylphosphine) ruthenium. 001 parts and 25 parts of composite particles (c3) were charged, and the temperature of the contents was kept at 3 ° C. while stirring and mixing. After flowing nitrogen into the contents to make the dissolved oxygen amount 1 ppm or less, 0.3 part of 1% aqueous solution of hydrogen peroxide, 0.8 part of 0.2% aqueous solution of ascorbic acid and 2,2′-azobis After adding and mixing 0.8 parts of a 2% aqueous solution of amidinopropane dihydrochloride to initiate polymerization and reaching 80 ° C., polymerization was performed at a polymerization temperature of 80 ± 2 ° C. for about 5 hours to obtain a hydrous gel. 0.125 parts of the diffusion penetrant (e2) is added to 400 parts of this hydrogel {water content 75%}, and 5 min at 25 ° C with a mincing machine (diameter hole diameter: 6 mm, 12VR-400K manufactured by Iizuka Kogyo Co., Ltd.). After kneading for 1 minute, it was dried with an aeration type band dryer under conditions of 135 ° C. and a wind speed of 2.0 m / sec to obtain a dried product. The dried product was pulverized with a commercially available juicer mixer {Matsushita Electric Industrial Co., Ltd., Fiber Mixer MX-X57}, adjusted to a particle size of 850 to 150 μm using a sieve with an opening of 850 and 150 μm, and then 100 parts of this dried product. Spray two parts of ethylene glycol diglycidyl ether 10% water / methanol mixed solution (water / methanol weight ratio = 70/30) while stirring at high speed (high speed stirring turbulizer manufactured by Hosokawa Micron: 2000 rpm). Then, the mixture was left to stand at 140 ° C. for 30 minutes to cross-link the surface to obtain the absorbent resin particles (12) of the present invention. The weight average particle diameter of the absorbent resin particles (12) was 400 μm.

<Example 13>
145.4 parts of acrylic acid was diluted with 9.4 parts of water, and neutralized by adding 242.3 parts of 25% aqueous sodium hydroxide while cooling to 20-30 ° C. To this solution was added 0.09 part of ethylene glycol diglycidyl ether, 0.0146 part of sodium hypophosphite monohydrate, 0.0727 part of potassium persulfate and 0.57 part of a diffusion penetrant (e1). After dissolution, 20 parts of composite particles (c4) were added, and the mixture was stirred and dispersed at 25 ° C. with a biomixer (ABM-2 type, manufactured by Nippon Seiki Co., Ltd.) to obtain a monomer aqueous dispersion.

  Subsequently, 624 parts of cyclohexane was put into a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas introduction tube, and polyoxyethylene octylphenyl ether phosphate ester (Daiichi Kogyo Seiyaku Co., Ltd., trade name: (Plysurf A210G) 1.56 parts was added and dissolved, and after purging with nitrogen while stirring, the temperature was raised to 70 ° C. Then, while maintaining the temperature at 70 ° C., the monomer aqueous dispersion was dropped at 6.6 parts / minute for 6 minutes and held at 75 ° C. for 15 minutes, and then the remaining monomer aqueous dispersion was 54 parts at 6.6 parts / minute. Added dropwise over a period of minutes. Thereafter, aging was performed at 75 ° C. for 30 minutes. Thereafter, water was removed by azeotropy with cyclohexane until the water content of the resin became about 20% (infrared moisture meter: FD-100 type, manufactured by Kett, measured at 180 ° C., 20 minutes). When the stirring was stopped after cooling to 30 ° C., the resin particles settled, and the resin particles and cyclohexane were separated by decantation. After adding 80 parts of the resin particles and 140 parts of cyclohexane to a reaction vessel, and adding 3.4 parts of a cyclohexane solution containing 0.4% glycerin polyglycidyl ether, the mixture is heated at 60 ° C. and held for 30 minutes. Further heating and holding under reflux of cyclohexane for 30 minutes. Next, the resin particles were separated by filtration and dried under reduced pressure at 80 ° C. to obtain absorbent resin particles (13) of the present invention. The weight average particle diameter of the absorbent resin particles (13) was 352 μm. In addition, content of a crosslinked polymer (a2-4) particle | grain is 9.7 weight% based on the weight of a crosslinked polymer (A1).

<Comparative Example 1>
Absorbent resin particles (H1) for comparison were obtained in the same manner as in Example 1 except that “composite particles (c1)” and “diffusion penetrant (e1)” were not used. The weight average particle diameter of the absorbent resin particles (H1) was 374 μm.

<Comparative Example 2>
Absorbent resin particles (H2) for comparison were obtained in the same manner as in Example 1 except that “composite particles (c1)” were not used. The weight average particle diameter of the absorbent resin particles (H2) was 374 μm.

<Comparative Example 3>
Absorbent resin particles (H3) for comparison in the same manner as in Example 1, except that “composite particles (c1)” were changed to “crosslinked polymer (a2-2) particles” obtained in Production Example 2. Got. The weight average particle diameter of the absorbent resin particles (H3) was 376 μm.

<Comparative example 4>
Absorbent resin particles for comparison (H4) for comparison in the same manner as in Example 1, except that “composite particles (c1)” were changed to “crosslinked polymer (a2-7) particles” obtained in Production Example 7. Got. The weight average particle diameter of the absorbent resin particles (H4) was 375 μm.

<Comparative Example 5>
Absorbent resin particles (H5) for comparison were obtained in the same manner as in Example 1, except that “40 parts of composite particles (c1)” was changed to “3 parts of composite particles (c2)”. The weight average particle diameter of the absorbent resin particles (H5) was 375 μm.

<Comparative Example 6>
Absorbent resin particles (H6) for comparison were obtained in the same manner as in Example 11 except that “composite particles (c3)” and “diffusion penetrant (e2)” were not used. The weight average particle diameter of the absorbent resin particles (H6) was 376 μm.

<Comparative Example 7>
Absorbent resin particles (H7) for comparison were obtained in the same manner as in Example 11 except that “composite particles (c3)” were not used. The weight average particle diameter of the absorbent resin particles (H7) was 374 μm.

<Comparative Example 8>
Absorbent resin particles for comparison (H8) for comparison in the same manner as in Example 11, except that “composite particles (c3)” were changed to “crosslinked polymer (a2-4) particles” obtained in Production Example 4. Got. The weight average particle diameter of the absorbent resin particles (H8) was 375 μm.

<Comparative Example 9>
Liquid obtained by dissolving 0.005 part of a hydrophobic substance {amino-modified silicone (product of Shin-Etsu Chemical Co., Ltd .: KF-861)} in 10 parts of methanol in 5 parts of the crosslinked polymer (a2-1) particles obtained in Production Example 1. After stirring for 2 minutes with a biomixer (ABM-2 type, manufactured by Nippon Seiki Co., Ltd.) at 25 ° C., it was dried at 60 ° C. for 1 hour to obtain a hydrophobic treatment material.

  400 parts of the hydrogel obtained in Production Example 1, 40 parts of the hydrophobic treatment material and 0.4 part of the diffusion penetrant (e1) are added to a mincing machine (hole diameter of the eye plate: 6 mm, 12VR-400K manufactured by Iizuka Kogyo Co., Ltd.). The mixture was kneaded at 25 ° C. for 5 minutes and then dried with an aeration band dryer under conditions of 135 ° C. and a wind speed of 2.0 m / sec to obtain a dried product. This dried product was pulverized with a commercially available juicer mixer {Matsushita Electric Industrial Co., Ltd., Fiber Mixer MX-X57}, adjusted to a particle size of 250 to 600 μm using a sieve having openings of 600 and 250 μm, and Spray two parts of ethylene glycol diglycidyl ether 10% water / methanol mixed solution (water / methanol weight ratio = 70/30) while stirring at high speed (high speed stirring turbulizer manufactured by Hosokawa Micron: 2000 rpm). Then, the mixture was left to stand at 140 ° C. for 30 minutes to cross-link the surface to obtain comparative absorbent resin particles (H9). The weight average particle diameter of the absorbent resin particles (H9) was 375 μm.

  About the absorptive resin particle obtained by the Example and the comparative example, the water retention amount, absorption amount under load, absorption time, and absorption time under load were measured, and it showed in Table 1.

<Measurement method of water retention>
After putting 1.00 g of a measurement sample into a tea bag (20 cm long, 10 cm wide) made of a nylon net having a mesh size of 63 μm and immersing in 1000 cc of physiological saline (salt concentration 0.9%) for 1 hour without stirring. After suspending for 15 minutes and draining, the tea bags were placed in a centrifuge, centrifuged at 150 G for 90 seconds to remove excess physiological saline, and the weight (h1) including the tea bag was measured. On the other hand, the tea bag weight (h2) was determined by the same operation except that no measurement sample was added. And water retention amount (g / g) was calculated | required by deducting weight (h2) from weight (h1). The physiological saline used and the temperature of the measurement atmosphere were 25 ° C. ± 2 ° C.

<Measurement method of absorption under load>
Weighing 0.1 g of a measurement sample in a cylindrical plastic tube (inner diameter 30 mm, height 60 mm) with a nylon mesh with a mesh opening of 63 μm (conforming to JIS Z8801-1: 2006) on the bottom, the plastic tube is vertical. A measurement sample was arranged on a nylon net so as to have a substantially uniform thickness, and a weight of 29.5 mm × 22 mm in outer diameter was placed on the measurement sample so as to obtain a load of 40 g / cm ² . In a petri dish (diameter: 12 cm) containing 60 ml of physiological saline (salt concentration 0.9%), place a plastic tube containing a measurement sample and a weight vertically, immerse the nylon mesh side on the bottom, and let it stand, After 60 minutes, the plastic tube containing the sample and the weight is weighed, and the weight of the measurement sample that has absorbed physiological saline is calculated. The value 10 times the increased weight is the absorbed amount under load with respect to physiological saline (g / G). The physiological saline used and the temperature of the measurement atmosphere were 25 ° C. ± 2 ° C.

<Measurement method of absorption time>
After weighing 1.0 g of the measurement sample into a 100 ml graduated cylinder, 100 ml of physiological saline is poured into the graduated cylinder at once, and reading of the volume occupied by the measurement sample (scale of the graduated cylinder corresponding to the upper end of the measurement sample) is started. did. Since the measurement sample swells due to the absorption of physiological saline, the volume occupied by the measurement sample increases, but reading of this volume is continued every minute, and the change in value for 5 minutes becomes ± 0. (The measurement sample reaches a saturated swelling state that can no longer absorb physiological saline after a certain period of time). Then, the horizontal axis represents time, the vertical axis represents the volume occupied by the measurement sample, and a graph representing the volume-time relationship is created. The volume (saturation swelling degree) when the change in the value for 5 minutes becomes ± 0. As 100 volume%, the time corresponding to 70 volume% with respect to the saturation swelling degree was defined as the absorption time (minutes). The physiological saline used and the temperature of the measurement atmosphere were 25 ° C. ± 2 ° C.

<Absorption time under load>
1.0 g of a measurement sample is weighed into a 100 ml graduated cylinder (inner diameter 27 mm), and a weight {G2 glass filter (Sakai Glass Tech Co., Ltd., thickness 5 mm, diameter 50 mm) is prepared in a disk with a diameter of 26 mm. A weight prepared by gluing. } Was placed on the measurement sample such that the glass filter surface was in contact with the measurement sample, and the absorption time under load (minutes) was determined in the same manner as the absorption time measurement method.

<Example 14>
A mixture obtained by mixing 100 parts of fluff pulp and 100 parts of the absorbent resin particles (1) of the present invention obtained in Example 1 with an airflow type mixing device is uniformly laminated so as to have a basis weight of about 400 g / m ^2. And it pressed for 30 seconds with the pressure of 5 Kg / cm < ² >, and the absorber (1) was obtained. Absorber (1) is cut into a 14cm x 36cm rectangle, and water absorbent paper (basis weight 15.5g / m ² , Oji Paper Co., Ltd., Napier Tissue Soft Slim) is placed on the top and bottom of each. Furthermore, by placing a polyethylene sheet (Canno Shokai Co., Ltd., poly sheet, thickness 0.03 mm) on the back and a polyethylene non-woven fabric (basis weight 20.0 g / m ² , DuPont, Tyvek) on the surface, a paper diaper (1) was created.

<Examples 15 to 26>
Paper diapers (2) to (13) were further produced in the same manner as in Example 14 except that the absorbent resin particles (1) were changed to any of the absorbent resin particles (2) to (13).

<Example 27>
After forming a layer of 50 parts of fluff pulp, 100 parts of the absorbent resin particles (2) obtained in Example 2 were uniformly dispersed, and a layer of 50 parts of fluff pulp was laminated thereon to form a sandwich structure. The absorber (14) was obtained by pressing at a pressure of 5 Kg / cm ² for 30 seconds. Absorber (14) is cut into a 14cm x 36cm rectangle, and water-absorbent paper (basis weight 15.5g / m ² , Oji Paper Co., Ltd., Napier Tissue Soft Slim) is placed on the top and bottom of each. Furthermore, by placing a polyethylene sheet (Canno Shokai Co., Ltd., poly sheet, thickness 0.03 mm) on the back and a polyethylene non-woven fabric (basis weight 20.0 g / m ² , DuPont, Tyvek) on the surface, a paper diaper (14) was created.

<Comparative Examples 10-18>
Comparative paper diapers (H1) to (H9) were prepared in the same manner as in Example 14 except that the absorbent resin particles (1) were changed to any of the absorbent resin particles (H1) to (H9). did.

  For the paper diapers (1) to (14) and (H1) to (H9), the amount of absorption until leakage, the surface dryness, and the surface dryness value by SDME were measured and are shown in Table 2.

<Absorption amount until leakage>
After placing a paper diaper (140 mm x 360 mm) on an acrylic board (140 mm x 360 mm, weight 0.5 kg), one end (upper end) of the short side (140 mm) of the paper diaper is fixed to the acrylic board with gum tape (paper diaper and gum tape) The acrylic plate was fixed at an angle of 45 degrees so that one end (upper end) on which the diaper was fixed was at the top. Then, artificial urine (0.03% by weight of calcium chloride, 0.08% by weight of magnesium sulfate, 0% by weight of sodium chloride) was placed 30 mm from the upper end {330 mm from the other end (lower end)} and 70 mm from both ends of the long side. 0.8 wt% and ion-exchanged water 99.09 wt%) was poured at a rate of 150 g / min with a dropping pump (manufactured by Sakai Sangyo Co., Ltd., trade name CP-21). The end point was the time when the artificial urine leaked from the lower end of the disposable diaper, and the amount of artificial urine poured from the beginning to the end of the pouring was defined as the “absorption amount until leakage”.

<Dry surface>
After measuring the amount of absorption until leakage, within 30 seconds, the surface of this paper diaper {250 mm from the top, 10 mm from the bottom, and 20 mm from both ends of the long side} is a 100 mm × 100 mm acrylic plate (45 g) And a 3 kg weight was placed on it and allowed to stand for 3 minutes. Subsequently, the acrylic board and the weight were removed, and within 30 seconds, the place where the acrylic board was covered was subjected to finger touch judgment by 10 panelists, and evaluated in the following four stages. The average value of 10 persons was calculated | required and this was made into the surface dry feeling.

2: Good dry feeling 1: Slightly moist but satisfactory level of dry feeling 0: Poor dry feeling, damp or wet, no wet feeling

  The absorbent resin particles of the present invention can be made into an absorbent article excellent in surface dry feeling by being applied to various absorbers. In particular, sanitary items such as paper diapers (children's disposable diapers and adult disposable diapers, etc.), napkins (such as sanitary napkins), paper towels, pads (such as incontinence pads and surgical underpads), and pet sheets (pet urine absorbing sheets) Suitable for supplies, and even for disposable diapers. The absorbent resin particles of the present invention are not only sanitary products, but also pet urine absorbents, urine gelling agents for portable toilets, freshness-preserving agents such as fruits and vegetables, meat and seafood drip absorbents, cold insulation agents, disposable warmers It is also useful for various applications such as battery gelling agents, water retention agents such as plants and soil, anti-condensation agents, water-stopping materials and packing materials, and artificial snow.

Claims (6)

A crosslinked polymer (A1) having the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the internal crosslinking agent (b) as essential constituent units;
Water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) and hydrophilic polymer (A2) on a part or all of the surface of crosslinked polymer (A2) particles having internal crosslinking agent (b) as essential constituent units Absorbent resin particles (D) comprising composite particles (C) coated or impregnated with B),
Absorbent resin particles having a structure containing part or all of the composite particles (C) inside the absorbent resin particles (D). The absorbent resin particle according to claim 1, wherein the hydrophilic substance (B) has an HLB value of 10 to 20. The absorbent resin particle according to claim 1, wherein the hydrophilic substance (B) is a polymer electrolyte. The absorbent resin particle according to any one of claims 1 to 3, further comprising a diffusion penetrant (E). An absorbent article using the absorbent resin particles according to any one of claims 1 to 4. Water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) and hydrophilic polymer (A2) on a part or all of the surface of crosslinked polymer (A2) particles having internal crosslinking agent (b) as essential constituent units Composite particles (C) coated or impregnated with B);
The water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the crosslinked polymer (A1) having the internal crosslinking agent (b) as essential constituent units are mixed and kneaded to obtain absorbent resin particles (D Or a part of the surface of the crosslinked polymer (A2) particles having the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the internal crosslinking agent (b) as essential constituent units, or Essential composition of water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) and internal cross-linking agent (b) in the presence of composite particles (C) that are all coated or impregnated with hydrophilic substance (B) A method for producing absorbent resin particles, comprising a step of obtaining a crosslinked polymer (A1) by polymerization as a unit and obtaining absorbent resin particles (D).