JP5162160B2 - Absorbent resin particles, production method thereof, absorbent body containing the same, and absorbent article - Google Patents

Description

  The present invention relates to absorbent resin particles, a production method thereof, an absorbent body including the same, and an absorbent article.

Examples of the water-absorbing agent having a good gel flow rate include a water-absorbing agent obtained by mixing a crosslinked polymer and water-insoluble spherical single particles (Patent Document 1), a crosslinked polymer and a cationic polymer compound. A water-absorbing agent obtained by mixing (Patent Document 2) is known.
JP 2003-225565 A JP 2003-062460 A

When a conventional water-absorbing agent is applied to an absorbent article {paper diaper, sanitary napkin, etc.}, even if initially exhibiting good absorption characteristics {absorption speed, surface dryness, etc.} There is a problem of getting worse. Therefore, when such an absorbent article is used for a long time, there is a problem that leakage occurs or the skin is fogged.
An object of the present invention is to provide absorbent resin particles that can maintain good absorption characteristics even when used for a long time when applied to absorbent articles.

The characteristic of the absorbent resin particle of the present invention is that the water-soluble vinyl monomer (a1) and / or the crosslinked polymer particle (A) obtained by polymerizing the hydrolyzable vinyl monomer (a2) and the crosslinking agent (b) The absorbent resin particles obtained by mixing the water-insoluble spherical single particles (c) and the binder (d) and heat-treating at 40 to 150 ° C.,
The gist of the present invention is that the gel flow rate retention ratio (GR) represented by the following formula is 50 to 100%.

Gel flow rate retention (GR) = (G2) × 100 / (G1)

(G2) is the gel flow rate immediately after being immersed in physiological saline for 24 hours (ml / min), and (G1) is the gel flow rate immediately after being immersed in physiological saline for 30 minutes (ml / min). ).

The gist of the absorbent body of the present invention is that it comprises the above-described absorbent resin particles and a fibrous material.
The gist of the absorbent article of the present invention is that the absorbent article is provided.

A feature of the method for producing 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 crosslinking agent (b) are subjected to a polymerization reaction so that the crosslinked polymer particles (A). (1) to obtain
The point is that it includes the step (2) of mixing the crosslinked polymer particles (A), the water-insoluble spherical single particles (c) and the binder (d), and heat-treating at 40 to 150 ° C. to obtain absorbent resin particles. To do.

  The absorbent resin particles of the present invention can maintain excellent absorption characteristics even when used for a long time when applied to absorbent articles. Therefore, even if the absorbent article to which the absorbent resin particles of the present invention are applied is used for a long time, there is no concern about leakage or fogging.

  The water-soluble vinyl monomer (a1) is not particularly limited, and known {e.g., vinyl monomers disclosed in Japanese Patent No. 3648553, Japanese Patent Laid-Open No. 2003-165883, Japanese Patent Laid-Open No. 2005-75982, Japanese Patent Laid-Open No. 2005-95759} can be used. .

  The hydrolyzable vinyl monomer (a2) means a vinyl monomer that becomes a water-soluble vinyl monomer (a1) by hydrolysis, and is not particularly limited (for example, Japanese Patent No. 3648553, Japanese Patent Application Laid-Open No. 2003-16583, Japanese Patent Application Laid-Open No. 2003-16583). 2005-75982, JP-A-2005-95759} vinyl monomers, and the like can be used. The hydrolysis of the hydrolyzable vinyl monomer may be performed either during the polymerization, after the polymerization, or both of them, but is preferably after the polymerization from the viewpoint of the molecular weight of the resulting absorbent resin particles.

  Of these, water-soluble vinyl monomers (a1) are preferred from the viewpoint of absorption characteristics, etc., more preferably anionic vinyl monomers, and more preferably carboxy (salt) groups, sulfo (salt) groups, amino groups, carbamoyl groups. Vinyl monomers having an ammonio group or a mono-, di- or tri-alkyl ammonio group, then preferably vinyl monomers having a carboxy (salt) group or a carbamoyl group, particularly preferably (meth) acrylic acid (salt) and (Meth) acrylamide, next particularly preferably (meth) acrylic acid (salt), most preferably acrylic acid (salt).

  The “carboxy (salt) group” means “carboxy group” or “carboxylate group”, and the “sulfo (salt) group” means “sulfo group” or “sulfonate group”. Moreover, (meth) acrylic acid (salt) means acrylic acid, acrylate, methacrylic acid or methacrylate, and (meth) acrylamide means acrylamide or methacrylamide. Examples of the salt include an alkali metal (such as lithium, sodium and potassium) salt, an alkaline earth metal (such as magnesium and calcium) salt, an ammonium (NH 4) salt, and the like. Among these salts, alkali metal salts and ammonium salts are preferable from the viewpoint of absorption characteristics and the like, more preferably alkali metal salts, and particularly preferably sodium salts.

  When either the water-soluble vinyl monomer (a1) or the hydrolyzable vinyl monomer (a2) is used as a structural unit, each may be used alone as a structural unit, or two or more kinds may be used as a structural unit if necessary. The same applies when (a1) and (a2) are used as structural units. Further, when the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as structural units, the content molar ratio (a1 / a2) is preferably 75/25 to 99/1, more preferably. 85/15 to 95/5, particularly preferably 90/10 to 93/7, and most preferably 91/9 to 92/8. Within this range, the absorption performance is further improved.

As a structural unit of the absorbent resin particles, in addition to the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), other vinyl monomers (a3) copolymerizable therewith can be used as the structural unit. .
Other vinyl monomers (a3) that can be copolymerized are not particularly limited and are known {for example, the hydrophobicity of Japanese Patent No. 3648553, JP-A No. 2003-165883, JP-A No. 2005-75982, JP-A No. 2005-95759} Vinyl monomers can be used.
When the other monomer (a3) is used as a structural unit, the content (mol%) of the other monomer (a3) unit is the number of moles of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit. Is preferably from 0.01 to 5, more preferably from 0.05 to 3, then preferably from 0.08 to 2, particularly preferably from 0.1 to 1.5. From the viewpoint of absorption characteristics, etc., the content of the other monomer (a3) unit is most preferably 0 mol%.

The cross-linking agent (b) is not particularly limited, and known {for example, an internal cross-linking agent described in Japanese Patent No. 3648553, JP-A No. 2003-165883, JP-A No. 2005-75982, JP-A No. 2005-95759} can be used.
Among these, from the viewpoint of absorption characteristics, an internal cross-linking agent having two or more ethylenically unsaturated groups is preferable, more preferably a poly (meth) allyl ether of a polyol having 2 to 10 carbon atoms, particularly preferably a triary. Rucyanurate, triallyl isocyanurate, tetraallyloxyethane and pentaerythritol triallyl ether, most preferably pentaerythritol triallyl ether.

  The content (mol%) of the crosslinking agent (b) unit is preferably 0.001 to 5, more preferably, based on the number of moles of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit. Is 0.005 to 3, particularly preferably 0.01 to 1. Within this range, the absorption characteristics are further improved.

  The water-insoluble spherical single particles (c) are not particularly limited as long as they are water-insoluble spherical single particles except for metal single particles, and may be either organic single particles or inorganic single particles. Metal single particles are not preferable because they may decompose the absorbent resin particles due to metal oxidation / reduction reactions when they contact the absorbent resin particles and water.

Organic single particles include: (i) organic single particles consisting only of hydrocarbons, (ii) organic single particles consisting of carbon atoms, hydrogen atoms and oxygen atoms, (iii) carbon atoms, hydrogen atoms, oxygen atoms and nitrogen atoms. And (iv) other organic single particles can be used.
The organic single particles preferably have a melting temperature equal to or higher than the drying temperature in order to prevent the organic single particles from melting in the drying step when producing the absorbent resin particles. The melting temperature (° C.) of the organic single particles is 130-300 are preferable, More preferably, it is 150-250.

(I) Examples of the organic single particles made of only hydrocarbons include single particles made of polyethylene, polypropylene, polystyrene, poly-p-xylylene, or polybutadiene.

(Ii) Organic single particles composed of carbon atoms, hydrogen atoms and oxygen atoms include polyacrylate, polymethacrylate, polyvinyl acetate, polyvinyl ether, thermoplastic polyester, polycarbonate, polyphenylene oxide, epoxy resin or acid-modified polyolefin. Particles and the like. The acid-modified polyolefin is a resin in which a carboxy group (—COOH), 1,3-oxo-2-oxapropylene (—COOCO—) or the like is introduced into the polyolefin {maleic acid-modified polyethylene, maleic acid-modified polypropylene, ethylene-acrylic. Acid copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, maleated polybutadiene, ethylene-vinyl acetate copolymer, and maleated product of ethylene-vinyl acetate copolymer} .

(Iii) Examples of the organic single particles composed of carbon atoms, hydrogen atoms, oxygen atoms, and nitrogen atoms include single particles composed of polyacrylonitrile, polyamide, or thermoplastic polyurethane.

(Iv) Other organic single particles may be obtained by copolymerizing two or more of polyvinyl chloride, polyvinylidene chloride, fluororesin, polysulfone, chlorinated polyethylene, or monomers constituting these resins. Single particles or the like.

  The weight average molecular weight of the organic single particle is preferably 1000 to 150,000, and more preferably 1000 to 10,000. The weight average molecular weight is a value measured by polystyrene permeation by a gel permeation chromatography (GPC) method.

  The inorganic single particles may be either natural inorganic single particles or synthetic inorganic single particles, oxides {silicon oxide, aluminum oxide, iron oxide, titanium oxide, magnesium oxide, zirconium oxide, etc.}, carbides {silicon carbide and aluminum carbide Etc.} or single particles made of nitride {titanium nitride, etc.}.

  Of the water-insoluble spherical single particles, inorganic single particles are preferable, single particles composed of oxides are more preferable, and silicon oxide single particles are particularly preferable. Among the silicon oxide single particles, amorphous silicon oxide single particles are most preferable.

  These water-insoluble spherical single particles may be a mixture of two or more kinds, or two or more kinds may be complexed {eg, zeolite and talc}.

  The pH {10 wt% aqueous solution, 25 ° C} of the water-insoluble spherical single particle (c) is preferably from 3 to 11, more preferably from 4 to 10, particularly preferably from 5 to 9. Within this range, the stability of the water-insoluble spherical single particles (c) is further improved. {In particular, in the case of inorganic single particles, secondary aggregation is further difficult. }.

  The primary particle diameter (nm) of the water-insoluble spherical single particle (c) is preferably 5 to 6000, more preferably 7 to 1000, and particularly preferably 15 to 50. Within this range, the absorption performance is further improved. The primary particle diameter is obtained by analyzing an image with an electron microscope {for example, a microscope with an image analysis device manufactured by Keyence Corporation: 3D Real Surface View Microscope VE-9800, 25 ° C.}.

  The secondary particle diameter (nm) of the water-insoluble spherical single particle (c) is preferably 6 to 7000, more preferably 30 to 2000, and particularly preferably 40 to 120. Within this range, the absorption characteristics are further improved. The secondary particle diameter is obtained by image analysis with an electron microscope {for example, a microscope with an image analysis device manufactured by Keyence Corporation: 3D real surface view microscope VE-9800, 25 ° C.}.

  The degree of association of the water-insoluble spherical single particles (c) is preferably 1 to 5, more preferably 1 to 2.7, and particularly preferably 1 to 1.7. Within this range, the absorption characteristics are further improved. The degree of association is a value obtained by (secondary particle diameter) / (primary particle diameter).

The specific surface area (m ² / g) of the water-insoluble spherical single particle (c) is preferably 1 to 380, more preferably 10 to 300, and particularly preferably 50 to 200. Within this range, the absorption characteristics are further improved. The specific surface area is measured according to JIS Z8830: 2001 (nitrogen, volume method, multipoint method).

The water-insoluble spherical single particle (c) can be easily obtained from the market. For example, the following products {chemical composition, pH (10 wt%, 25 ° C), primary particle size (nm), secondary particle size (nm) ), Specific surface area (m ² / g)} and the like.

-PL-1 {Aqueous dispersion of silicon oxide (concentration of silicon oxide 12% by weight), 7, 15, 40, 200}, PL-2L {Aqueous dispersion of silicon oxide (of silicon oxide) Concentration, 20% by weight), 7, 15, 30, 170}, PL-3 {silicon oxide aqueous dispersion (silicon oxide concentration 20% by weight), 7, 35, 70, 80}, PL-7 {silicon oxide Aqueous dispersion (silicon oxide concentration 20 wt%), 7, 70, 120, 40}, PL-20 {silicon oxide aqueous dispersion (silicon oxide concentration 24 wt%), 7, 220, 370, 10 }, SP-03B {silicon oxide, 7, 200, 300, 12}

・ Nippon Aerosil Co., Ltd. (Aerosil is a registered trademark of Degussa Aktiengesellschaft)
Aerosil 50 {silicon oxide, 5, 30,-, 50}, Aerosil 130 {silicon oxide, 4, 16,-, 130}, Aerosil 200 {silicon oxide, 4, 12,-, 200}, Aerosil 200V {silicon oxide 4, 12,-, 200}, Aerosil 200CF {silicon oxide, 4, 12,-, 200}, Aerosil 200FAD {silicon oxide, 4, 12,-, 200}, Aerosil 300 {silicon oxide, 4, 7, -, 300}, Aerosil 300CF {silicon oxide, 4, 7,-, 300}, Aerosil 380 {silicon oxide, 4, 7,-, 380}

・ Product made by Nissan Chemical Industries, Ltd. (Snowtex is a registered trademark of Nissan Chemical Industries, Ltd.)
SNOWTEX XS {Aqueous dispersion of silicon oxide (concentration of silicon oxide 20% by weight), 9, 5,-,-}, SNOXTEX OXS {Aqueous dispersion of silicon oxide (concentration of silicon oxide 10% by weight), 3 5,-,-}, Snowtex S {silicon oxide aqueous dispersion (silicon oxide concentration 30% by weight), 10, 10,-,-}, Snowtex OS {silicon oxide aqueous dispersion (silicon oxide , 3, 10,-,-}, Snowtex 20 {silicon oxide aqueous dispersion (silicon oxide concentration 20% by weight), 10, 15,-,-}, Snowtex 30 {Oxidation Aqueous dispersion of silicon (concentration of silicon oxide 30% by weight), 10, 15,-,-}, Snowtex 40 {Aqueous dispersion of silicon oxide (concentration of silicon oxide 40% by weight), 10, 15,-, -}, Snowtex O { Aqueous dispersion of silicon fluoride (concentration of silicon oxide 20% by weight), 3, 15,-,-}, Snowtex N {Aqueous dispersion of silicon oxide (concentration of silicon oxide 20% by weight), 10, 15,- ,-}, SNOWTEX C {silicon oxide aqueous dispersion (silicon oxide concentration 20% by weight), 10, 15,-,-}, SNOWTEX AK {silicon oxide aqueous dispersion (silicon oxide concentration 19% by weight) %), 5, 15, −, −}, SNOWTEX 50 {aqueous dispersion of silicon oxide (concentration of silicon oxide 48% by weight), 9, 25, −, −}, SNOWTEX O-40 {of silicon oxide Aqueous dispersion (silicon oxide concentration 40% by weight), 3, 25,-,-}, Snowtex CM {Silicon oxide aqueous dispersion (silicon oxide concentration 30% by weight), 10, 25,-,-} , Snowtex 20L {Silicon oxide water Spray (concentration of silicon oxide 20% by weight), 10, 45,-,-}, Snowtex OL {silicon oxide aqueous dispersion (concentration of silicon oxide 20% by weight), 3, 45,-,-}, Snowtex XL {Aqueous dispersion of silicon oxide (concentration of silicon oxide 40% by weight), 10, 50,-,-}, Snowtex ZL {Aqueous dispersion of silicon oxide (concentration of silicon oxide 40% by weight), 10 , 85,-,-}, MP-2040 {Aqueous dispersion of silicon oxide (concentration of silicon oxide 40% by weight), 9,200,-,-}, MP-4540M {Aqueous dispersion of silicon oxide (silicon oxide) Concentration of 40% by weight), 9, 450,-,-}

-AZ Electronic Materials Co., Ltd. (KLEBOSOL is a registered trademark of Azette Electronic Materials USA Corporation)
KLEBOSOL 30CAL25 {Aqueous dispersion of silicon oxide (concentration of silicon oxide 30% by weight) 4, 25,-, 130}, KLEBOSOL 30HB50K {Aqueous dispersion of silicon oxide (concentration of silicon oxide 30% by weight), 3, 50 ,-, 60}, KLEBOSOL 30HB25K {Aqueous dispersion of silicon oxide (concentration of silicon oxide 30% by weight), 3, 25,-, 130}, KLEBOSOL 30N50 {Aqueous dispersion of silicon oxide (concentration of silicon oxide 30% by weight) %) 10, 50,-, 60}

・ Mitsui Chemicals Co., Ltd. (Kemipearl is a registered trademark of Mitsui Chemicals, Inc.)
Chemipearl W401 {Polyolefin aqueous dispersion (polyolefin concentration 40% by weight), 9,1000,-,-}, Chemipearl W4005 {Polyolefin aqueous dispersion (polyolefin concentration 40% by weight), 11, 600,-,- }, Chemipearl WF640 {Polyolefin aqueous dispersion (polyolefin concentration 40% by weight), 11, 1000,-,-}, Chemipearl W700 {Polyolefin aqueous dispersion (polyolefin concentration 40% by weight), 10, 1000,- ,-}, Chemipearl W900 {Polyolefin aqueous dispersion (polyolefin concentration 40 wt%), 11, 600,-,-}, Chemipearl W950 {Polyolefin aqueous dispersion (polyolefin concentration 40 wt%), 11,600 ,-,-}, Chemipearl WP100 {Polyolefin Aqueous dispersion (concentration of 40 wt% of a polyolefin), 11,1000, -, -}, Chemipearl V300 {aqueous dispersion of the polyolefin (concentration 40 wt% of a polyolefin), 8,6000, -, -}

  The content (% by weight) of the water-insoluble spherical single particles (c) is based on the weight of the water-soluble vinyl monomer (a1), hydrolyzable vinyl monomer (a2), other monomer (a3) and crosslinking agent (b) If no degradable vinyl monomer or other monomer is used, these weights are not included. same as below. } Is preferably 0.01 to 1, more preferably 0.05 to 0.75, and particularly preferably 0.1 to 0.5. Within this range, the absorption characteristics and the mechanical strength of the absorbent resin particles are further improved.

  The binder (d) exhibits a role for fixing the water-insoluble spherical single particles (c) on the surface of the absorbent resin particles. Examples of the binder (d) include polyvalent glycidyl, polyvalent amine, polyvalent isocyanate, polyhydric alcohol, alkoxysilane, and polyvalent aziridine.

  As polyvalent glycidyl, ethylene glycol diglycidyl ether, polyoxyethylene glycol diglycidyl ether, glycerin diglycidyl ether, diglycerin diglycidyl ether, propylene glycol diglycidyl ether, polyoxypropylene glycol diglycidyl ether, polyglycerin diglycidyl ether , Polyglycerin triglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, resorcin diglycidyl ether, bisphenol A diglycidyl ether, trimethylolpropane diglycidyl ether and trimethylol Propane triglycidylate Etc. The.

  As polyvalent amine, ethylenediamine, diethanolamine, triethanolamine, diethylenetriamine, triethylenetetramine, propylenediamine, 1,4-butanediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, Decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tetradecamethylenediamine, hexadecamethylenediamine, 1-amino-2,2-bis (aminomethyl) butane, tetraaminomethane, norbornenediamine, 1,4-diamino Cyclohexane, 1,3,5-triaminocyclohexane, isophoronediamine, 1,1,1-tris (2′-aminomethyl) ethane, tetrakis (2′-aminomethyl) Tan, 1,1,1-tris (2′-aminoethyl) ethane, tetrakis (2′-aminoethyl) ethane, 1,1,1-tris (2′-aminopropyl) ethane, tetrakis (2′-amino) Propyl) methane, 1,1,1-tris (2′-aminobutyl) ethane, tetrakis (2′-aminobutyl) methane, 1,2,3-tris (aminomethyl) benzene, 1,2,4-tris Examples include (aminomethyl) benzene and 1,2,5-tris (aminomethyl) benzene.

  Examples of the polyvalent isocyanate include hexamethylene diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), and 4,4-diphenylmethane diisocyanate. (MDI), p-phenylene diisocyanate, m-phenylene diisocyanate, 1,5-naphthylene diisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate and Bicycloheptane triisocyanate etc. are mentioned.

  As polyhydric alcohols, diethylene glycol, ethylene glycol, propylene glycol, glycerin, pentaerythritol, sorbitol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polyglycerin, 1,3-butane Diol, 1,4-butanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,6-hexanediol, 2,5-hexanediol , Trimethylolpropane and polyvinyl alcohol.

  As alkoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropylmethyldimethoxysilane, aminosilane , 3-phenylaminopropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-gridoxypropyltrimethoxysilane, 3-gridoxypropyltriethoxysilane, 3-gridoxypropylmethyldimethoxysilane, 3-gridoxypropyl Methyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, bis (3- (triethoxysilyl) propyl) disulfide, bis (3- (triethoxysilyl) propyl) tetra Rufide, vinyltriacetoxysilane, vinyltris (methoxyethoxy) silane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, allyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyl Dimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, N- (1,3-dimethylbutylidene) -3 -Aminopropyltriethoxysilane, isobutyltrimethoxysilane, cyclohexylmethyldimethoxysilane, n-decyltrimethoxysilane, diisopropyldimethoxysilane, n Propyltrimethoxysilane, diisobutyldimethoxysilane, ethyltrimethoxysilane, dimethyldimethoxysilane, n-octyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, methyl Examples include triphenoxysilane, tetraethoxysilane, bis (trimethoxysilyl) hexane, diphenyldimethoxysilane, trifluoropropyltrimethoxysilane, and 3-chloropropyltrimethoxysilane.

Examples of the polyvalent aziridines include 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate] and 4,4′-bis (ethyleneiminocarbonylamino) diphenylmethane.
In addition, the surface crosslinking agent mentioned later can be used as it is as binder (d).

  Among these binders, polyhydric glycidyl, polyhydric amine, polyhydric isocyanate, polyhydric alcohol and alkoxysilane are preferable from the viewpoint of absorption characteristics, and more preferably polyhydric glycidyl, polyhydric amine and polyhydric isocyanate, particularly Preferred are polyvalent glycidyl and polyvalent amine, most preferably polyvalent glycidyl.

  A surface cross-linking agent described later may be included in the binder (d), or a surface cross-linking agent may be used as the binder (d). In particular, as described later, when the crosslinked polymer particles (A) that are not surface-crosslinked are used, a surface crosslinking agent is included in the binder (d), or a surface crosslinking agent is used as the binder (d). The water-insoluble spherical single particles (c) can be fixed with the binder (d) and at the same time surface-crosslinked.

  The content (% by weight) of the binder (d) is based on the weight of the water-soluble vinyl monomer (a1), the hydrolyzable vinyl monomer (a2), the other monomer (a3) and the crosslinking agent (b). 001 to 0.5 is preferable, 0.03 to 0.3 is more preferable, and 0.005 to 0.15 is particularly preferable. Within this range, the absorption characteristics are further improved.

  From the viewpoint of absorption characteristics, the gel flow rate retention rate (%) of the absorbent resin particles of the present invention is preferably 50 to 100, more preferably 60 to 100, particularly preferably 70 to 100, and most preferably 80 to 100. 100.

  The gel flow rate retention rate (%) is determined by the gel flow rate (G1) (ml / min) immediately after the measurement sample is immersed in physiological saline for 30 minutes, and the measurement sample is immersed in physiological saline for 24 hours. The gel flow rate (G2) (ml / min) immediately after measurement is measured and determined from the following equation.

Gel flow rate retention (GR) = (G2) × 100 / (G1)

<Measurement method of gel flow rate (see FIGS. 1 and 2)>
A hydrogel particle (2) is prepared by immersing 0.32 g of a measurement sample in 150 ml of physiological saline (1; salt concentration of 0.9% by weight) for 30 minutes or 24 hours.
The cylinder (3) standing upright (diameter (inner diameter) 25.4 mm, length 40 cm, and scale lines (4, 5) are provided at positions 40 ml and 60 ml from the bottom. }, The cock (7) is closed in a filtration cylindrical tube having a wire mesh {6; opening 106 μm, JIS Z8801-1: 2006} and an openable / closable cock {7; inner diameter 5 mm, length 10 cm}. In this state, the prepared hydrogel particles (2) were transferred together with physiological saline, and then a circular wire mesh {8; mesh size 150 μm, diameter 25 mm} was perpendicular to the wire mesh surface on the water-containing gel particles (2). A pressure shaft (9; weight 22 g, length 47 cm) to be attached to the wire is placed so that the wire mesh and the hydrogel particles are in contact with each other, and a weight {10; 88.5 g} is placed on the pressure shaft (9), Let stand for 1 minute.

  Subsequently, the cock (6) is opened, and the time (T1; seconds) required for the liquid level in the filtration cylindrical tube to change from the 60 ml scale line (4) to the 40 ml scale line (5) is measured. Determine the rate (ml / min). The temperature of the physiological saline used and the measurement atmosphere is 25 ° C. ± 2 ° C.

Gel flow rate (ml / min) = 20 ml × 60 / (T1-T2)

  T2 is a time measured by the same operation as described above when no measurement sample is present.

  The absorbent resin particles of the present invention preferably contain a hydrophobic substance (e). When the hydrophobic substance (e) is included, the absorption characteristics are further improved. Examples of the hydrophobic substance (e) include a hydrophobic substance containing a hydrocarbon group, a hydrophobic substance containing a hydrocarbon group having a fluorine atom, and a hydrophobic substance having a polysiloxane structure.

  Examples of the hydrophobic substance containing a hydrocarbon group include polyolefin resins, polyolefin resin derivatives, polystyrene resins, polystyrene resin derivatives, waxes, long chain fatty acid esters, long chain fatty acids, and mixtures of two or more thereof.

  As the polyolefin resin, an olefin having 2 to 4 carbon atoms {ethylene, propylene, isobutylene, isoprene, etc.} as an essential constituent monomer (the olefin content is at least 50% by weight based on the weight of the polyolefin resin) And polymers having an average molecular weight of 1,000 to 1,000,000 {for example, polyethylene, polypropylene, polyisobutylene, poly (ethylene-isobutylene), isoprene, etc.}.

  Examples of the polyolefin resin derivative include polymers having a weight average molecular weight of 1,000 to 1,000,000 introduced by introducing a carboxyl group (—COOH), 1,3-oxo-2-oxapropylene (—COOCO—) or the like into a polyolefin resin {for example, polyethylene heat Degradation, polypropylene thermal degradation, maleic acid modified polyethylene, chlorinated polyethylene, maleic acid modified polypropylene, ethylene-acrylic acid copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, maleation Polybutadiene, ethylene-vinyl acetate copolymer, and maleated product of ethylene-vinyl acetate copolymer}.

  As the polystyrene resin, a polymer having a weight average molecular weight of 1,000 to 1,000,000 can be used.

  As the polystyrene resin derivative, a polymer having a weight average molecular weight of 1,000 to 1,000,000 (for example, styrene-containing styrene as an essential constituent monomer (the content of styrene is at least 50% by weight based on the weight of the polystyrene derivative)). Maleic anhydride copolymer, styrene-butadiene copolymer, styrene-isobutylene copolymer, etc.}.

  Examples of the wax include waxes having a melting point of 50 to 200 ° C. (for example, paraffin wax, beeswax, carbana wax, beef tallow, etc.).

  As long-chain fatty acid esters, esters of fatty acids having 8 to 25 carbon atoms and alcohols having 1 to 5 carbon atoms {for example, methyl laurate, ethyl laurate, methyl stearate, ethyl stearate, methyl oleate, oleic acid Ethyl, glycerin lauric acid monoester, glycerin stearic acid monoester, glycerin oleic acid monoester, pentaerythritol lauric acid monoester, pentaerythritol stearate monoester, pentaerythritol oleic acid monoester, sorbit lauric acid monoester, Sorbite stearic acid monoester, sorbite oleic acid monoester, beef tallow and the like}.

  Examples of the long chain fatty acid include fatty acids having 8 to 25 carbon atoms (for example, lauric acid, lauric acid, stearic acid, oleic acid, dimer acid, and behenic acid).

  Examples of the mixture of two or more of these include a mixture of a polyolefin resin and a polystyrene resin derivative {for example, a mixture of polyethylene and a styrene-maleic anhydride copolymer}.

  Examples of the hydrophobic substance containing a hydrocarbon group having a fluorine atom include perfluoroalkane, perfluoroalkene, perfluoroaryl, perfluoroalkyl ether, perfluoroalkyl carboxylic acid, perfluoroalkyl alcohol, and two or more kinds thereof. Mixtures and the like are included.

  As perfluoroalkanes, alkanes having 4 to 42 fluorine atoms and 1 to 20 carbon atoms {for example, trifluoromethane, pentafluoroethane, pentafluoropropane, heptafluoropropane, heptafluorobutane, nonafluorofluorohexane, tridecafluoro Octane and heptadecafluorododecane, etc.}.

  The perfluoroalkene includes alkenes having 4 to 42 fluorine atoms and 2 to 20 carbon atoms (for example, trifluoroethylene, pentafluoropropene, trifluoropropene, heptafluorobutene, nonafluorofluorohexene, tridecafluorooctene and hepta Decafluorododecene etc.}.

  Perfluoroaryl includes aryl having 4 to 42 fluorine atoms and 6 to 20 carbon atoms (for example, trifluorobenzene, pentafluorotoluene, trifluoronaphthalene, heptafluorobenzene, nonafluorofluoroxylene, tridecafluorooctylbenzene and Heptadecafluorododecylbenzene, etc.}.

  Examples of perfluoroalkyl ether include ethers having 2 to 82 fluorine atoms and 2 to 40 carbon atoms (for example, ditrifluoromethyl ether, dipentafluoroethyl ether, dipentafluoropropyl ether, diheptafluoropropyl ether, diheptafluoro). Butyl ether, dinonafluorofluorohexyl ether, ditridecafluorooctyl ether, diheptadecafluorododecyl ether, etc.}.

  Examples of perfluoroalkylcarboxylic acids include carboxylic acids having 3 to 41 fluorine atoms and 1 to 21 carbon atoms (for example, pentafluoroethanoic acid, pentafluoropropanoic acid, heptafluoropropanoic acid, heptafluorobutanoic acid, nonafluorofluorohexane). Acid, tridecafluorooctanoic acid, heptadecafluorododecanoic acid, and salts of these metals (alkali metal and alkaline earth metal etc.), etc.}.

  Perfluoroalkyl alcohols include alcohols having 3 to 41 fluorine atoms and 1 to 20 carbon atoms (for example, pentafluoroethanol, pentafluoropropanol, heptafluoropropanol, heptafluorobutanol, nonaflufluorohexanol, tridecafluorooctanol and Heptadecafluorododecanol and the like} and ethylene oxide (1 to 20 mol per 1 mol of alcohol) adduct of this alcohol.

  Examples of the mixture of two or more of these include a mixture of perfluoroalkylcarboxylic acid and perfluoroalkyl alcohol {for example, a mixture of pentafluoroethanoic acid and pentafluoroethanol, etc.}.

  Examples of the hydrophobic substance having a polysiloxane structure include polydimethylsiloxane, polyether-modified polysiloxane {polyoxyethylene-modified polysiloxane and poly (oxyethylene / oxypropylene) -modified polysiloxane, etc.}, carboxy-modified polysiloxane, and epoxy-modified polysiloxane. Examples include siloxane, amino-modified polysiloxane, alkoxy-modified polysiloxane, and the like, and mixtures thereof.

  The position of the organic group (modified group) of the modified silicone {polyether-modified polysiloxane, carboxy-modified polysiloxane, epoxy-modified polysiloxane, amino-modified polysiloxane, etc.} is not particularly limited, but the side chain of polysiloxane, polysiloxane Both ends of the polysiloxane, one end of the polysiloxane, and both the side chain and both ends of the polysiloxane may be used. Among these, from the viewpoint of absorption characteristics and the like, both the side chain of polysiloxane and the side chain and both ends of polysiloxane are preferred, and both the side chain and both ends of polysiloxane are more preferred.

  Examples of the organic group (modified group) of the polyether-modified polysiloxane include a group containing a polyoxyethylene group or a poly (oxyethylene / oxypropylene) group. The content (pieces) of oxyethylene groups and / or oxypropylene groups contained in the polyether-modified polysiloxane is preferably 2 to 40, more preferably 5 to 30, particularly preferably per molecule of the polyether-modified polysiloxane. 7-20, most preferably 10-15. Within this range, the absorption characteristics are further improved. Moreover, when it contains an oxyethylene group and an oxypropylene group, the content (% by weight) of the oxyethylene group is preferably 1 to 30, more preferably 3 to 25, and particularly preferably 5 based on the weight of the polysiloxane. ~ 20. Within this range, the absorption characteristics are further improved.

The polyether-modified silicone can be easily obtained from the market. For example, the following products {modified position, type of oxyalkylene} can be preferably exemplified.
* Shin-Etsu Chemical Co., Ltd. KF-945 {side chain, oxyethylene and oxypropylene}, KF-6020 {side chain, oxyethylene and oxypropylene}, X-22-6191 {side chain, oxyethylene and oxypropylene} X-22-4922 {side chain, oxyethylene and oxypropylene}, X-22-4272 {side chain, oxyethylene and oxypropylene}, X-22-6266 {side chain, oxyethylene and oxypropylene}

FZ-2110 {both ends, oxyethylene and oxypropylene}, FZ-2122 {both ends, oxyethylene and oxypropylene}, FZ-7006 {both ends, oxyethylene and oxypropylene}, manufactured by Toray Dow Corning Co., Ltd. FZ-2166 {both ends, oxyethylene and oxypropylene}, FZ-2164 {both ends, oxyethylene and oxypropylene}, FZ-2154 {both ends, oxyethylene and oxypropylene}, FZ-2203 {both ends, oxy Ethylene and oxypropylene} and FZ-2207 {both ends, oxyethylene and oxypropylene}

  The organic group (modified group) of the carboxy-modified polysiloxane includes a group containing a carboxy group, and the organic group (modified group) of the epoxy-modified polysiloxane includes a group containing an epoxy group. Examples of the organic group (modified group) of polysiloxane include groups containing amino groups (1, 2, and tertiary amino groups). The organic group (modified group) content (g / mol) of these modified silicones is preferably 200 to 11000, more preferably 600 to 8000, and particularly preferably 1000 to 4000 as carboxy equivalent, epoxy equivalent or amino equivalent. It is. Within this range, the absorption characteristics are further improved. The carboxy equivalent is measured according to “16. Total acid value test” of JIS C2101: 1999. Moreover, an epoxy equivalent is calculated | required based on JISK7236: 2001. The amino equivalent is measured according to “8. Potentiometric titration method (base number / hydrochloric acid method)” of JIS K2501: 2003.

The carboxy-modified silicone can be easily obtained from the market. For example, the following products {modified position, carboxy equivalent (g / mol)} can be preferably exemplified.
* Shin-Etsu Chemical Co., Ltd. X-22-3701E {side chain, 4000}, X-22-162C {both ends, 2300}, X-22-3710 {single end, 1450}

-BY 16-880 {side chain, 3500}, BY 16-750 {both ends, 750}, BY 16-840 {side chain, 3500}, SF8418 {side chain, 3500} manufactured by Toray Dow Corning Co., Ltd.

Epoxy-modified silicones can be easily obtained from the market. For example, the following products {modified position, epoxy equivalent} can be preferably exemplified.
・ X-22-343 {side chain, 525}, KF-101 {side chain, 350}, KF-1001 {side chain, 3500}, X-22-2000 {side chain, 620} manufactured by Shin-Etsu Chemical Co., Ltd. X-22-2046 {side chain, 600}, KF-102 {side chain, 3600}, X-22-4741 {side chain, 2500}, KF-1002 {side chain, 4300}, X-22-3000T {Side chain, 250}, X-22-163 {both ends, 200}, KF-105 {both ends, 490}, X-22-163A {both ends, 1000}, X-22-163B {both ends, 1750}, X-22-163C {both ends, 2700}, X-22-169AS {both ends, 500}, X-22-169B {both ends, 1700}, X-22-173DX {single end, 4500} , X-22-9002 { Side chain, both ends, 5000}

-FZ-3720 {side chain, 1200}, BY 16-839 {side chain, 3700}, SF 8411 {side chain, 3200}, SF 8413 {side chain, 3800}, SF 8421 {manufactured by Toray Dow Corning Co., Ltd. Side chain, 11000}, BY 16-876 {side chain, 2800}, FZ-3736 {side chain, 5000}, BY 16-855D {side chain, 180}, BY 16-8 {side chain, 3700}

The amino-modified silicone can be easily obtained from the market. For example, the following products {modified position, amino equivalent} can be preferably exemplified.
-Shin-Etsu Chemical Co., Ltd. KF-865 {side chain, 5000}, KF-864 {side chain, 3800}, KF-859 {side chain, 6000}, KF-393 {side chain, 350}, KF-860 {Side Chain, 7600}, KF-880 {Side Chain, 1800}, KF-8004 {Side Chain, 1500}, KF-8002 {Side Chain, 1700}, KF-8005 {Side Chain, 11000}, KF-867 {Side Chain, 1700}, X-22-3820W {Side Chain, 55000}, KF-869 {Side Chain, 8800}, KF-861 {Side Chain, 2000}, X-22-3939A {Side Chain, 1500} , KF-877 {side chain, 5200}, PAM-E {both ends, 130}, KF-8010 {both ends, 430}, X-22-161A {both ends, 800}, X-22-161B {both Terminal 1500 }, KF-8012 {both ends, 2200}, KF-8008 {both ends, 5700}, X-22-1660B-3 {both ends, 2200}, KF-857 {side chain, 2200}, KF-8001 { Side chain, 1900}, KF-862 {side chain, 1900}, X-22-9192 {side chain, 6500}

-FZ-3707 {side chain, 1500}, FZ-3504 {side chain, 1000}, BY 16-205 {side chain, 4000}, FZ-3760 {side chain, 1500}, FZ manufactured by Toray Dow Corning Co., Ltd. -3705 {side chain, 4000}, BY 16-209 {side chain, 1800}, FZ-3710 {side chain, 1800}, SF 8417 {side chain, 1800}, BY 16-849 {side chain, 600}, BY 16-850 {side chain, 3300}, BY 16-879B {side chain, 8000}, BY 16-892 {side chain, 2000}, FZ-3501 {side chain, 3000}, FZ-3785 {side chain, 6000}, BY 16-872 {side chain, 1800}, BY 16-213 {side chain, 2700}, BY 16-203 {side chain, 1900}, BY 16-898 {side chain, 2900 BY 16-890 {side chain, 1900}, BY 16-893 {side chain, 4000}, FZ-3789 {side chain, 1900}, BY 16-871 {both ends, 130}, BY 16-853C {both Terminal 360}, BY 16-853U {both ends, 450}

  Examples of the mixture include a mixture of polydimethylsiloxane and carboxyl-modified polysiloxane, and a mixture of polyether-modified siloxane and amino-modified siloxane.

  Of these hydrophobic substances (e), a hydrophobic substance having a polysiloxane structure is preferable from the viewpoint of absorption characteristics and the like, more preferably modified silicone, particularly preferably polyether-modified polysiloxane, amino-modified polysiloxane and carboxy. Modified polysiloxanes, then preferably amino-modified and carboxyl-modified polysiloxanes, most preferably carboxyl-modified polysiloxanes.

The viscosity (mPa · s, 25 ° C.) of the hydrophobic substance having a polysiloxane structure is preferably 10 to 5000, more preferably 15 to 3000, and particularly preferably 20 to 1500. Within this range, the absorption characteristics are further improved. The viscosity is JIS Z8803-1991 “Viscosity of liquid”. Cone and cone-measured according to the viscosity measurement method using a flat plate rotational viscometer {for example, E-type viscometer with temperature adjusted to 25.0 ± 0.5 ° C. (RE80L, Toki Sangyo Co., Ltd., radius 7 mm) , Angle 5.24 × 10 ⁻² rad cone). }

The HLB value of the hydrophobic substance (e) is preferably 1 to 10, more preferably 1.5 to 9, and particularly preferably 2 to 8. Within this range, the absorption characteristics are further improved.
The HLB value means a hydrophilic-hydrophobic balance (HLB) value, and is determined by the Oda method (new introduction to surfactants, page 197, Takehiko Fujimoto, Sanyo Chemical Industries, Ltd., published in 1981). .

  When the hydrophobic substance (e) is included, the content (% by weight) of the hydrophobic substance (e) is determined based on the water-soluble vinyl monomer (a1), hydrolyzable vinyl monomer (a2), other monomers (a3) and Based on the weight of the crosslinking agent (b), 0.001-1 is preferable, 0.003-0.2 is more preferable, and 0.005-0.02 is particularly preferable. Within this range, the absorption characteristics are further improved.

  The absorbent resin particles of the present invention may contain other additives (for example, known preservatives, fungicides, antibacterial agents, antioxidants, ultraviolet rays (for example, JP 2003-225565 A, JP 2006-131767 A). Absorbers, colorants, fragrances, deodorants, inorganic powders, organic fibrous materials, etc.}.

  100-800 are preferable, as for the weight average particle diameter (micrometer) of the absorptive resin particle | grains of this invention, More preferably, it is 200-500, Most preferably, it is 300-400. Within this range, the absorption performance is further improved.

  In addition, the weight average particle diameter is determined by using a conventional method, for example, a low-tap test sieve shaker and a standard sieve (JIS Z8801-1: 2006), Perry's Chemical Engineers Handbook, 6th edition (Mac Glow Hill). * Book cum bunny, 1984, p. 21). That is, a JIS standard sieve is 1000 μm from the top, 850 μm, 710 μm, 500 μm, 425 μm, 355 μm, 250 μm and 150 μm, and the order of the saucer, or 500 μm, 355 μm, 250 μm, 150 μm, 125 μm, 75 μm and 45 μm from the top Combine in order. About 50 g of the measured particles are put in the uppermost screen and shaken for 5 minutes with a low-tap test sieve shaker. Weigh the measured particles on each sieve and the pan, and calculate the weight fraction of the particles on each sieve with the total as 100% by weight. This value is the logarithmic probability paper {the horizontal axis is the sieve aperture (particle size ), The vertical axis is plotted in the weight fraction}, a line connecting the points is drawn, and the particle diameter corresponding to the weight fraction of 50% by weight is obtained, and this is defined as the weight average particle diameter.

  In addition, since the absorption performance is better when the content of fine particles is smaller, the content of fine particles of 106 μm or less (preferably 150 μm or less) in the total particles is preferably 3% by weight or less, more preferably 1% by weight or less. It is. 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 particle of the present invention is not particularly limited, and examples thereof include an irregular crushed shape, a flake shape, a pearl shape, and a rice grain shape. Among these, when applied to a paper diaper or the like, from the viewpoint of good entanglement with the fibrous material, no fear of dropping off from the fibrous material, and from the viewpoint of absorption performance, an irregularly crushed shape and a pearl shape are preferable.

  The absorbent resin particle of the present invention is a step of obtaining a crosslinked polymer particle (A) by polymerizing a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) and a crosslinking agent (b) (1 And a step (2) of mixing the crosslinked polymer particles (A), the water-insoluble spherical single particles (c) and the binder (d), and heat-treating as necessary to obtain absorbent resin particles. It is preferable to do.

  Step (1) is a known aqueous solution polymerization {adiabatic polymerization, thin film polymerization, spray polymerization method, etc .; JP-A-55-133413, etc.}, or known reverse-phase suspension polymerization {JP-B-54-30710, JP No. 56-26909 and Japanese Patent Laid-Open No. 1-5808}.

  The crosslinked polymer particles (A) can be subjected to a surface crosslinking treatment with a surface crosslinking agent, if necessary. As the surface crosslinking agent, known {for example, JP 59-189103, JP 58-180233, JP 61-16903, JP 61-2111305, JP 61-252212, Surface cross-linking agents {polyvalent glycidyl, polyhydric alcohol, polyvalent amine, polyvalent aziridine, polyvalent isocyanate, silane coupling agent and polyvalent metal of JP-A-51-136588 and JP-A-61-257235} Etc.} can be used. Of these surface cross-linking agents, from the viewpoints of economy and absorption characteristics, polyvalent glycidyl, polyvalent amine and silane coupling agent are preferred, more preferred are polyvalent glycidyl and silane coupling agent, and particularly preferred are polyvalent glycidyl. Most preferred is ethylene glycol diglycidyl ether.

  In the case of surface cross-linking treatment, the amount (% by weight) of the surface cross-linking agent is not particularly limited because it can be variously changed depending on the type of surface cross-linking agent, the conditions for cross-linking, the target performance, etc. In view of the above, based on the weight of the water-soluble vinyl monomer (a1), the hydrolyzable vinyl monomer (a2), the other monomer (a3) and the crosslinking agent (b), 0.001 to 3 is preferable, and more preferable. Is 0.005 to 2, particularly preferably 0.01 to 1.

  In the case of performing the surface cross-linking treatment, a known method {for example, Japanese Patent No. 3648553, JP-A No. 2003-165883, JP-A No. 2005-75982, JP-A No. 2005-95759} can be applied.

  In the step (2), as a method (order) of mixing the crosslinked polymer particles (A), the water-insoluble spherical single particles (c) and the binder (d), (2-1) the crosslinked polymer particles (A), Method of mixing water-insoluble spherical single particles (c) and binder (d) at the same time; (2-2) Crosslinking polymer particles (A) and water-insoluble spherical single particles (c) are mixed, A method of mixing the binder (d); (2-3) A method of mixing the water-insoluble spherical single particles (c) and the binder (d) and then mixing the mixture and the crosslinked polymer particles (A). And (2-4) a method of mixing the crosslinked polymer particles (A) and the binder (d) and then mixing the mixture and the water-insoluble spherical single particles (c). Among these, (2-1), (2-2), and (2-3) are preferable from the viewpoint of absorption characteristics, and (2-1) is more preferable.

  The water-insoluble spherical single particle (c) may be used in any form of a solid (powder) or a dispersion, but is preferably used in a dispersion from the viewpoint of uniformity. When used as a dispersion, water or the like is preferable as the solvent.

  The binder (d) is preferably used in the form of a solution, an emulsion or a dispersion. When used as a solution, emulsion or dispersion, the solvent is preferably water, alcohol {ethylene glycol, diethylene glycol or the like}, and the like.

  The use amount (% by weight) of the water-insoluble spherical single particles (c) is preferably 0.01 to 1, more preferably 0.05 to 0.75, especially based on the weight of the crosslinked polymer particles (A). Preferably it is 0.1-0.5. Within this range, the absorption characteristics and the mechanical strength of the absorbent resin particles are further improved.

  The used amount (% by weight) of the binder (d) is preferably 0.001 to 0.5, more preferably 0.003 to 0.3, particularly preferably based on the weight of the crosslinked polymer particles (A). 0.005 to 0.15. Within this range, the absorption characteristics are further improved.

  The mixing temperature (° C.) is preferably 30 to 150, more preferably 40 to 120, and particularly preferably 50 to 100. Within this range, it becomes easier to mix evenly and the absorption characteristics are further improved.

  As a mixing device, a known device {double-arm kneader, internal mixer (Banbury mixer), self-cleaning mixer, gear compounder, screw-type extruder, screw-type kneader, mincing machine, turbulizer, cylindrical mixing Machine, V-shaped mixer, ribbon-type mixer, screw-type mixer, double-arm-type mixer, pulverizing-type kneader, groove-type mixer, vertical-type mixer, etc.} can be used. These can be used in combination.

  In order to increase the reactivity between the crosslinked polymer particles (A) and the binder (d), a reaction catalyst may be used or heat treatment may be performed. It does not restrict | limit especially as a reaction catalyst, Any of an acid catalyst, a basic catalyst, and a metal catalyst may be sufficient.

  Examples of the acid catalyst, the basic catalyst, and the metal catalyst are known {eg, JP 2001-011119 A, JP 2003-119386 A, JP 2002-317047 A, JP 2000-044686 A, etc.}. The reaction catalysts described can be used.

  Among these catalysts, acid catalysts include mineral acids {such as sulfuric acid and hydrochloric acid}, carboxylic acids {such as acetic acid, chloroacetic acid, citric acid, formic acid, propionic acid, succinic acid and maleic acid}, sulfonic acids {methanesulfonic acid and p-toluenesulfonic acid}, phosphate esters {monooctyl phosphate, monopropyl phosphate and monolauryl phosphate, etc.}, phosphate diesters {dioctyl phosphate, dipropyl phosphate and dilauryl phosphate} are preferable, and more preferable. Are mineral acids, carboxylic acids and sulfonic acids, particularly preferably mineral acids and sulfonic acids.

  In addition, basic catalysts include alkali hydroxides {sodium hydroxide and potassium hydroxide} and amines {ethylenediamine, hexanediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, piperidine, metaphenylenediamine, ethanolamine and Triethylamine, etc.} is preferred, more preferably sodium hydroxide, potassium hydroxide, ethylenediamine, hexadiamine, diethylenetriamine, ethanolamine and triethylamine, particularly preferably sodium hydroxide, potassium hydroxide and triethylamine.

Examples of the metal catalyst include titanium compounds {tetraisopropoxytitanium, tetranormalbutoxytitanium, tetrakis (2-ethylhexyloxy) titanium, tetrastearyloxytitanium, etc.}, and aluminum compounds {triethoxyaluminum, triisopropoxyaluminum, mono Secondary butoxydipropoxyaluminum and trisecondary butoxyaluminum etc.} are preferred, more preferably tetraisopropoxytitanium, tetranormalbutoxytitanium, tetrakis (2-ethylhexyloxy) titanium,
Triethoxyaluminum, triisopropoxyaluminum, monosecondary butoxydipropoxyaluminum and trisecondary butoxyaluminum, particularly preferably tetraisopropoxytitanium, tetranormalbutoxytitanium, triethoxyaluminum and triisopropoxyaluminum.

  When a reaction catalyst is used, the amount (% by weight) of the reaction catalyst used is preferably 0.01 to 1, more preferably 0.03 to 0.5, particularly preferably 0, based on the weight of the binder (d). 0.05 to 0.1. Within this range, the reactivity between the crosslinked polymer particles (A) and the binder (d) is further improved.

  When heat-processing, 30-150 are preferable, as for heating temperature (degreeC), More preferably, it is 40-120, Most preferably, it is 50-100. Within this range, the reactivity between the crosslinked polymer particles (A) and the binder (d) is further improved. Further, the heating time (minutes) is preferably 10 to 300, more preferably 20 to 180, and particularly preferably 30 to 60. Within this range, the reactivity between the crosslinked polymer particles (A) and the binder (d) is further improved.

  In the step (2), it is preferable to mix the hydrophobic substance (e) together with the mixture of the crosslinked polymer particles (A), the water-insoluble spherical single particles (c) and the binder (d).

  The hydrophobic substance (e) is preferably used in the form of a solution, an emulsion or a dispersion. When used as a solution, emulsion or dispersion, the solvent is preferably water, alcohol {methanol, ethanol, ethylene glycol, diethylene glycol, etc.} and the like.

  When the hydrophobic substance (e) is used, the usage amount (% by weight) of the hydrophobic substance (e) is preferably 0.001 to 1, more preferably, based on the weight of the crosslinked polymer particles (A). It is 0.003-0.2, Most preferably, it is 0.005-0.02. Within this range, the absorption characteristics are further improved.

  The absorbent resin particles of the present invention can be used as an absorbent body together with a fibrous material. The structure and production method of the absorber are the same as those known in the art (Japanese Patent Laid-Open No. 2003-225565, Japanese Patent Laid-Open No. 2006-131767, Japanese Patent Laid-Open No. 2005-097569, etc.). Moreover, it is preferable that this absorber comprises absorbent articles {paper diapers, sanitary napkins, etc.}.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Unless otherwise specified, “part” means “part by weight” and “%” means “% by weight”. The gel flow rate retention rate was measured by the method described above, and the water retention amount, the absorption amount under load, and the performance of the disposable diaper were evaluated by the following methods.

<Measurement method of water retention>
1.00 g of a measurement sample is put into a tea bag (20 cm long, 10 cm wide) made of a nylon net having a mesh size of 63 μm (JIS Z8801-1: 2006), and 1,000 ml of physiological saline (saline concentration 0.9% by weight). After being immersed in the inside for 1 hour without stirring, it was suspended for 15 minutes and drained. Thereafter, each tea bag was 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 to obtain the water retention amount from the following formula. In addition, the temperature of the used physiological saline and measurement atmosphere was 25 degreeC +/- 2 degreeC.

Water retention amount (g / g) = (h1)-(h2)

  (H2) is the weight of the tea bag measured by the same operation as described above when there is no measurement sample.

<Measurement method of absorption under load>
Weighing 0.16 g of a measurement sample screened at 250 to 500 μm in a cylindrical plastic tube (inner diameter: 25 mm, height: 34 mm) with a nylon mesh of 63 μm mesh (JIS Z8801-1: 2006) attached to the bottom. After the cylindrical plastic tube is placed vertically and the measurement sample is arranged on the nylon net so as to have a substantially uniform thickness, a weight (weight: 310.6 g, outer diameter: 24.5 mm) is placed on the measurement sample. Was put on. After measuring the weight (M1) of the entire cylindrical plastic tube, a cylindrical type containing a measurement sample and a weight in a petri dish (diameter: 12 cm) containing 60 ml of physiological saline (salt concentration 0.9% by weight). The plastic tube was set up vertically and immersed with the nylon mesh side as the bottom surface and allowed to stand for 60 minutes. After 60 minutes, pull up the cylindrical plastic tube from the petri dish, tilt it diagonally, remove the dripping water drops, weigh the entire cylindrical plastic tube containing the measurement sample and weight (M2), and From this, the amount of absorption under pressure was determined. In addition, the temperature of the used physiological saline and measurement atmosphere was 25 degreeC +/- 2 degreeC.

Absorption under load (g / g) = {(M2)-(M1)} / 0.16

<Example 1>
Water-soluble vinyl monomer (a1-1) {acrylic acid, manufactured by Mitsubishi Chemical Corporation, purity 100%} 131 parts, crosslinking agent (b-1) {pentaerythritol triallyl ether, manufactured by Daiso Corporation} 0.44 parts And 362 parts of deionized water were kept at 3 ° C. with stirring and mixing. After flowing nitrogen into this mixture to reduce the dissolved oxygen amount to 1 ppm or less, 0.5 part of 1% aqueous hydrogen peroxide solution, 1 part of 2% aqueous ascorbic acid solution and 2% 2,2′-azobisamidinopropane Polymerization was started by adding and mixing 0.1 part of a dihydrochloride aqueous solution. After the temperature of the mixture reached 80 ° C., a water-containing gel was obtained by polymerization at 80 ± 2 ° C. for about 5 hours.

  Next, while this hydrated gel was chopped with a mincing machine (12VR-400K manufactured by ROYAL), 180 parts of 30% aqueous sodium hydroxide solution was added and mixed and neutralized to obtain a neutralized gel. Further, the neutralized gel was dried with a ventilation band dryer {140 ° C., wind speed 2 m / sec} to obtain a dried product. The dried product was pulverized with a juicer mixer (Osterizer BLENDER manufactured by Oster Co., Ltd.) and then sieved to adjust the particle size to a particle size range of 710 to 150 μm to obtain crosslinked polymer particles {dried particles} (A1). . Next, 100 parts of the crosslinked polymer particles {dried particles} (A1) were stirred at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed: 2000 rpm), and an aqueous dispersion of water-insoluble spherical single particles (c1) was added thereto. {PL-1, an aqueous dispersion of spherical silicon oxide manufactured by Fuso Chemical Industries, Ltd., primary particle size 15 nm, concentration 12%} 2.5 parts, binder (d1) {containing ethylene glycol diglycidyl ether at a concentration of 10% Water / methanol mixed solution (water / methanol = 70/30)} 1.5 parts and uniformly mixed, and then allowed to stand at 150 ° C. for 30 minutes to obtain the absorbent resin particles (1) of the present invention. Got.

<Example 2>
Water-soluble vinyl monomer (a1-1) {acrylic acid} 131 parts water-soluble vinyl monomer (a1-2) {sodium acrylate} 123.14 parts and water-soluble vinyl monomer (a1-1) {acrylic acid} 36. It was changed to 69 parts, the cross-linking agent (b-1) {pentaerythritol triallyl ether} 0.44 parts was changed to the cross-linking agent (b-2) {ethylene glycol diglycidyl ether} 0.3 parts, 1. 362 parts of ionic water were changed to 333 parts, and 30% aqueous sodium hydroxide solution was not added, mixed, or neutralized, water dispersion of water-insoluble spherical single particles (c1) (concentration 12%) 5 parts of an aqueous dispersion of water-insoluble spherical single particles (c2) {Snowtex OXS, an aqueous dispersion of spherical silicon oxide manufactured by Nissan Chemical Industries, Ltd., primary particle diameter 5 nm, concentration 10%} 3 Was changed to, in the same manner as in Example 1 to obtain an absorbent resin particles of the present invention (2).

<Example 3>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water dispersion of water-insoluble spherical single particles (c3) {Snowtex XL, water of spherical silicon oxide manufactured by Nissan Chemical Industries, Ltd. In the same manner as in Example 1, except that the dispersion, primary particle diameter 45 nm, concentration 20%} was changed to 5 parts, and the amount of binder (d1) used was changed from 1.5 parts to 5 parts. Absorbent resin particles (3) were obtained.

<Example 4>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water dispersion of water-insoluble spherical single particles (c4) {PL-20, spherical silicon oxide water manufactured by Fuso Chemical Industries, Ltd. Example 1 except that the dispersion, primary particle size 220 nm, concentration 20%} was changed to 0.05 parts, and the amount of binder (d1) used was changed from 1.5 parts to 0.01 parts. Thus, absorbent resin particles (4) of the present invention were obtained.

<Example 5>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water dispersion of water-insoluble spherical single particles (c5) {PL-7, water of spherical silicon oxide manufactured by Fuso Chemical Co., Ltd. Example 1 except that the dispersion was changed to a primary particle diameter of 70 nm, concentration 20%} 0.25 parts, and the amount of binder (d1) used was changed from 1.5 parts to 0.03 parts. Thus, absorbent resin particles (5) of the present invention were obtained.

<Example 6>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water dispersion of water-insoluble spherical single particles (c6) {PL-2L, spherical silicon oxide water manufactured by Fuso Chemical Industry Co., Ltd. In the same manner as in Example 1, except that the dispersion, the primary particle diameter 15 nm, the concentration 20%} was changed to 3.75 parts, and the amount of the binder (d1) used was changed from 1.5 parts to 3 parts. Absorbent resin particles (6) of the present invention were obtained.

<Example 7>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water-insoluble spherical single particles (c7) {AEROSIL300, spherical silicon oxide manufactured by Nippon Aerosil Co., Ltd., primary particle diameter 7 nm} 0.05 The absorbent resin particles (7) of the present invention were obtained in the same manner as in Example 1 except that the amount of the binder (d1) was changed from 1.5 parts to 0.05 parts. .

<Example 8>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water-insoluble spherical single particles (c8) {AEROSIL 380, spherical silicon oxide manufactured by Nippon Aerosil Co., Ltd., primary particle diameter 7 nm} 0.5 Absorbent resin particles (8) of the present invention were obtained in the same manner as in Example 1, except that the part was changed to the part.

<Example 9>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water dispersion of water-insoluble spherical single particles (c9) {KLEBOSOL30CAL25, aqueous dispersion of spherical silicon oxide manufactured by AZ Electronic Materials Co., Ltd. The absorbent resin particles (9) of the present invention were obtained in the same manner as in Example 1 except that the primary particle diameter was 25 nm and the concentration was changed to 30%} 0.334 part.

<Example 10>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water dispersion of water-insoluble spherical single particles (c10) {Chemipearl W401, water-dispersed spherical particles of polyolefin manufactured by Mitsui Chemicals, Inc. The absorbent resin particles (10) of the present invention were obtained in the same manner as in Example 1 except that the primary particle diameter was changed to 1 μm and the concentration was 40%} 0.25 parts.

<Example 11>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water dispersion of water-insoluble spherical single particles (c11) {Chemical WP100, water-dispersed spherical particles of polyolefin manufactured by Mitsui Chemicals, Inc. Absorbent resin particles (11) of the present invention were obtained in the same manner as in Example 1 except that the primary particle diameter was changed to 1 μm and the concentration was 40%} 0.25 parts.

<Example 12>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water dispersion of water-insoluble spherical single particles (c12) {Chemical V300, water-dispersed spherical particles of polyolefin manufactured by Mitsui Chemicals, Inc. The absorbent resin particles (12) of the present invention were obtained in the same manner as in Example 1 except that the primary particle diameter was changed to 6 μm and the concentration was 40%} 0.25 parts.

<Example 13>
2.5 parts of an aqueous dispersion {solid content 12%} of water-insoluble spherical single particles (c1) is mixed with water of water-insoluble spherical single particles (c13) {AEROSIL200, spherical silicon oxide manufactured by Nippon Aerosil Co., Ltd., primary particle diameter 12 nm}. Absorbent resin particles (13) of the present invention were obtained in the same manner as in Example 1, except that the dispersion (concentration: 30%) was changed to 0.334 parts.

<Example 14>
After 121.2 parts of cyclohexane and 0.9 part of sorbitan monostearate were uniformly dissolved, nitrogen gas was blown to adjust the amount of dissolved oxygen to 1 ppm or less to adjust the reaction solvent. On the other hand, 70 parts of 25% aqueous sodium hydroxide solution was added to a mixed liquid of 45 parts of acrylic acid and 6.4 parts of water under ice cooling to neutralize 70 mol% of the carboxy group. Subsequently, 0.0054 part of ethylene glycol diglycidyl ether, 0.0546 part of sodium hypophosphite and 0.031 part of 2,2′-azobisamidinopropane dihydrochloride were added and dissolved to prepare a monomer solution. .

  Next, while stirring the reaction solvent, the monomer solution was dispersed therein, and then the temperature of the dispersion was heated to 60 ° C. while bubbling nitrogen, followed by polymerization for 2 hours while maintaining the temperature at 60 ± 2 ° C. Water-containing gel particles were obtained. Then, it heated from 60 degreeC to 80 degreeC, water was distilled off by azeotropy of cyclohexane and water, and the water | moisture content in a water-containing gel particle was 20%. Next, after the precipitated hydrogel particles are separated from the cyclohexane phase by decantation, the separated hydrogel particles are dried under reduced pressure (80 to 90 ° C., 0.01 MPa) to obtain crosslinked polymer particles {dried particles} (A2). Obtained. While 30 parts of the crosslinked polymer particles {dry particles} (A2) were stirred at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), an aqueous dispersion of water-insoluble spherical single particles (c1) {concentration 12% } After adding 0.75 part and 0.45 part of binder (d1) while spraying with a two-fluid sprayer and mixing uniformly, the mixture is allowed to stand at 140 ° C. for 30 minutes to obtain the absorbent resin particles ( 14) was obtained.

<Example 15>
While 100 parts of the crosslinked polymer particles {Dry particle} (A1) obtained in Example 1 were stirred at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), the concentration of the surface crosslinking agent {ethylene glycol diglycidyl ether was increased. 1.5 parts of a water / methanol mixed solution (water / methanol = 70/30)} contained at 10% is added to the crosslinked polymer particles {dried particles} (A1) and mixed uniformly. Then, crosslinked polymer particles {dried particles} (A3) were obtained. Next, the aqueous dispersion {concentration 12%} of the water-insoluble spherical single particles (c1) while the crosslinked polymer particles {dried particles} (A3) were stirred at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm). 2.5 parts, 0.15 part of binder (d2) {3-aminopropyltrimethoxysilane} and 0.15 part of acid catalyst {aqueous solution containing p-toluenesulfonic acid at a concentration of 0.1%} The resultant was added to the coalesced particles {dry particles} (A3), mixed uniformly, and then allowed to stand at 80 ° C. for 30 minutes to obtain absorbent resin particles (15) of the present invention.

<Example 16>
The absorbent resin particles (16 of the present invention) were obtained in the same manner as in Example 15 except that 0.15 part of the binder (d2) was changed to 0.15 part of the binder (d3) {3-glycoxypropyltrimethoxysilane}. )

<Example 17>
0.15 part of binder (d2) was changed to 0.15 part of binder (d4) {hexamethylene diisocyanate}, 0.15 part of acid catalyst was a basic catalyst {aqueous solution containing triethylamine at a concentration of 0.1%} Absorbent resin particles (17) of the present invention were obtained in the same manner as in Example 15 except that the amount was changed to 0.15 part.

<Example 18>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water dispersion of water-insoluble spherical single particles (c14) {Chemipearl W4005, aqueous dispersion of polyolefin manufactured by Mitsui Chemicals, Ltd., primary Other than changing particle size 600nm, concentration 40%} 0.25 parts, changing binder (d2) 0.15 parts to binder (d5) {ethylenediamine} 0.1 parts, not using acid catalyst The absorbent resin particles (18) of the present invention were obtained in the same manner as in Example 15.

<Example 19>
Water dispersion of water-insoluble spherical single particles (c1) {concentration 12%} 2.5 parts of water-insoluble spherical single particles (c15) {AEROSIL 50, spherical silicon oxide manufactured by Nippon Aerosil Co., Ltd., primary particle diameter 30 nm} 0.3 Absorbent resin particles (19) of the present invention were obtained in the same manner as in Example 15 except that the parts were changed to parts.

<Example 20>
When adding 2.5 parts of aqueous dispersion {concentration 12%} of water-insoluble spherical single particles (c1) and 1.5 parts of binder (d1), hydrophobic substance (e1) {BY16-849, Absorbent resin particles (20) of the present invention were obtained in the same manner as in Example 1 except that 2 parts of a methanol solution (silicone concentration: 1%) of amino-modified silicone manufactured by Toray Dow Corning Co., Ltd. was also added.

<Example 21>
When 2.5 parts of aqueous dispersion {concentration 12%} of water-insoluble spherical single particles (c1) and 1.5 parts of binder (d1) are added, the hydrophobic substance (e2) {X-22- 3701E, Shin-Etsu Chemical Co., Ltd. carboxyl-modified silicone} methanol solution (silicone concentration: 1%) 0.5 parts was added in the same manner as in Example 1 except that the absorbent resin particles (21) of the present invention were used. Obtained.

<Example 22>
When adding 2.5 parts of aqueous dispersion {concentration 12%} of water-insoluble spherical single particles (c1) and 1.5 parts of binder (d1), hydrophobic substance (e3) {FZ-3504, Absorbent resin particles (22) of the present invention were obtained in the same manner as in Example 1 except that 20 parts of a methanol solution (silicone concentration: 1%) of amino-modified silicone manufactured by Toray Dow Corning Co., Ltd. was also added.

<Example 23>
0.15 part of binder (d2) was changed to 0.15 part of binder (d4) {hexamethylene diisocyanate}, 0.15 part of acid catalyst was a basic catalyst {aqueous solution containing triethylamine at a concentration of 0.1%} Changed to 0.15 parts, added 2.5 parts of aqueous dispersion of water-insoluble spherical single particles (c1) {concentration 12%}, 0.15 parts of binder (d4) and 0.15 parts of basic catalyst In addition to the addition of 0.3 part of a methanol solution (silicone concentration 1%) of the hydrophobic substance (e4) {BY 16-879B, amino-modified silicone manufactured by Toray Dow Corning Co., Ltd.} In the same manner as in No. 15, absorbent resin particles (23) of the present invention were obtained.

<Example 24>
The water dispersion {concentration 12%} of the water-insoluble spherical single particle (c1) 2.5 parts was changed to 0.25 part of the water dispersion {concentration 40%} of the water-insoluble spherical single particle (c3), binder ( d2) Water dispersion of water-insoluble spherical single particles (c3) {concentration 40%} 0 except that 0.15 part was changed to 0.1 part of binder (d5) {ethylenediamine} and no acid catalyst was used. When adding 25 parts and 0.1 part of binder (d5), a methanol solution of the hydrophobic substance (e5) {KF-8005, amino-modified silicone manufactured by Shin-Etsu Chemical Co., Ltd.} (silicone concentration 1%) ) Absorbent resin particles (24) of the present invention were obtained in the same manner as in Example 15 except that 0.1 part was also added.

<Example 25>
When adding 2.5 parts of aqueous dispersion {concentration 12%} of water-insoluble spherical single particles (c1) and 1.5 parts of binder (d1), the hydrophobic substance (e6) {X-22- 163, Absorbent resin particles (25) of the present invention were obtained in the same manner as in Example 1 except that 10 parts of a methanol solution (epoxy modified silicone manufactured by Shin-Etsu Chemical Co., Ltd.) 10 parts was also added. .

<Comparative Example 1>
Absorbent resin particles (H1) for comparison were obtained in the same manner as in Example 1 except that the binder (d1) was not used.

<Comparative example 2>
Absorbent resin particles (H2) for comparison were obtained in the same manner as in Example 15 except that the binder (d2) and the acid catalyst were not used.

<Comparative Example 3>
Absorbent resin particles (H3) for comparison were obtained in the same manner as in Example 18 except that the binder (d5) was not used.

<Comparative example 4>
Absorbent resin particles (H4) for comparison were obtained in the same manner as in Example 19 except that the binder (d2) and the acid catalyst were not used.

<Comparative Example 5>
Absorbent resin particles (H5) for comparison were obtained in the same manner as in Example 21 except that the binder (d1) was not used.

<Comparative Example 6>
Absorbent resin particles (H6) for comparison were obtained in the same manner as in Example 23 except that the binder (d4) and the basic catalyst were not used.

  For the absorbent resin particles obtained in Examples 1 to 25 and Comparative Examples 1 to 6, the gel permeation rate retention rate and the performance evaluation result {water retention amount, absorption amount under load} are shown in Tables 1 to 3 {numbers relating to structural units. Represents parts by weight. }.

  As can be seen from Tables 1 to 3, the absorbent resin particles (Examples 1 to 25) of the present invention had a remarkably high gel flow rate retention compared to the absorbent resin particles of Comparative Examples 1 to 6. Subsequently, it was evaluated what absorption characteristics would be exhibited when applied to an absorbent article when the gel flow rate retention rate was high.

<Preparation of absorbent articles (paper diapers)>
100 parts of fluff pulp and 100 parts of an evaluation sample {absorbent resin particles} were mixed with an airflow type mixing apparatus {Pad former manufactured by Autech Co., Ltd.} to obtain a mixture. m ² and so as to uniformly acrylic plate stacked on (thickness 4 mm), and pressed for 30 seconds at a pressure of 5Kg / cm ^2, to obtain an absorbent. The absorbent body is cut into a 14 cm × 36 cm rectangle, and water absorbent paper (basis weight: 15.5 g / m ² , manufactured by Advantech Co., Ltd., filter paper No. 2) having the same size as the absorbent body is arranged above and below each. A paper diaper was prepared by arranging a polyethylene sheet (polyethylene film UB-1 manufactured by Tamapoly Co., Ltd.) on the back surface and a non-woven fabric (basis weight 20 g / m ² , Eltas Guard manufactured by Asahi Kasei Co., Ltd.) on the surface.

About this paper diaper, the surface dryness value by SDME was evaluated, and the result was shown in Tables 4 and 5.
<Surface dryness value by SDME method>
A disposable diaper (artificial urine (0.03% by weight of potassium chloride, 0.08% by weight of magnesium sulfate, 0.08% by weight of magnesium sulfate, 0.8% by weight of sodium chloride) in which the detector of the SDME (Surface Dryness Measurement Equipment) tester (manufactured by WK system) is sufficiently moistened. % And deionized water 99.09% by weight) and a paper diaper was soaked for 60 minutes. }, A 0% dryness value was set, and then the detector of the SDME tester was prepared by drying a paper diaper {paper diaper at 80 ° C. for 2 hours by heating. } Was set to 100% dryness, and the SDME tester was calibrated. Next, a metal ring (inner diameter 70 mm, length 50 mm) is set in the center of the paper diaper to be measured, and 80 ml of artificial urine is injected, until the artificial urine is completely absorbed from the start of injection until the gloss due to the artificial urine cannot be confirmed. } Was measured, and this value was taken as the absorption rate (1). When the artificial urine has been absorbed, immediately remove the metal ring, place an SDME detector in the center of the paper diaper, start measuring the surface dryness value, and measure the value 5 minutes after the start of measurement as the surface dryness value (1). did.

  After measuring the surface dryness value (1), leave it for 24 hours, and after 24 hours, inject 80 ml of artificial urine again and measure the time from the start of injection until the artificial urine is completely absorbed. Was the absorption rate (2), and the surface dryness value (2) was obtained in the same manner as described above. The artificial urine, measurement atmosphere, and standing atmosphere were 25 ± 5 ° C. and 65 ± 10% RH.

  As can be seen from Tables 4 to 5, the absorbent article using the absorbent resin particles of the present invention has an absorption rate (2) and a surface dryness value (2) as compared to the absorbent article using the comparative absorbent resin particles. ) Was significantly better. That is, the absorbent resin particles of the present invention were able to maintain excellent absorption characteristics even when used for a long time when applied to absorbent articles. Therefore, even if the absorbent article to which the absorbent resin particles of the present invention are applied is used for a long time, it is easily predicted that there is no risk of leakage or fogging.

  The absorbent resin particles of the present invention can be applied to an absorbent body containing absorbent resin particles and a fibrous material, and absorbent articles {paper diapers, sanitary napkins, and medical blood retaining bodies comprising the absorbent body. It is useful for the agent}. In addition, pet urine absorbent, urine gelling agent for portable toilets, freshness preservation agent for fruits and vegetables, drip absorbent for meat and seafood, cooler, disposable warmer, battery gelling agent, water retention agent for plants and soil, dew condensation It can also be used in various applications such as inhibitors, water-stopping agents, packing agents and artificial snow.

It is sectional drawing which represented typically the filtration cylindrical tube for measuring a gel flow rate. It is the perspective view which represented typically the pressurization axis | shaft for measuring a gel liquid flow rate, and a weight.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Saline 2 Hydrous gel particle 3 Cylinder 4 60 ml scale line 5 40 ml scale line 6 Wire mesh 7 Cock 8 Circular wire mesh 9 Pressure shaft 10 Weight

Claims (12)

Cross-linked polymer particles (A) obtained by polymerizing water-soluble vinyl monomer (a1) and / or hydrolyzable vinyl monomer (a2) and cross-linking agent (b), water-insoluble spherical single particles (c) and binder Absorbent resin particles obtained by mixing (d) with heat treatment at 40 to 150 ° C.,
Absorbent resin particles having a gel flow rate retention ratio (GR) represented by the following formula of 50 to 100%.

Gel flow rate retention (GR) = (G2) × 100 / (G1)

(G2) is the gel flow rate immediately after being immersed in physiological saline for 24 hours (ml / min), and (G1) is the gel flow rate immediately after being immersed in physiological saline for 30 minutes (ml / min). ). The absorbent resin particle according to claim 1, wherein the binder (d) is at least one selected from the group consisting of polyvalent glycidyl, polyvalent amine, polyvalent isocyanate, polyhydric alcohol and alkoxysilane. Based on the weight of the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the crosslinking agent (b), the content of the water-insoluble spherical single particles (c) is 0.01 to 1% by weight, The absorbent resin particle according to claim 1 or 2, wherein the content of the binder (d) is 0.001 to 0.5% by weight. Furthermore, the absorptive resin particle in any one of Claims 1-3 containing hydrophobic substance (e). The content of the hydrophobic substance (e) is 0.001 to 1% by weight based on the weight of the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) and the crosslinking agent (b). Item 5. Absorbent resin particles according to Item 4. An absorbent comprising the absorbent resin particles according to any one of claims 1 to 5 and a fibrous material. An absorbent article comprising the absorbent body according to claim 6. A step (1) of obtaining a crosslinked polymer particle (A) by polymerizing a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) and a crosslinking agent (b);
A step (2) in which the crosslinked polymer particles (A), the water-insoluble spherical single particles (c) and the binder (d) are mixed and heat-treated at 40 to 150 ° C. to obtain absorbent resin particles. A method for producing absorbent resin particles. The step (2) is a step in which the crosslinked polymer particles (A), the water-insoluble spherical single particles (c) and the binder (d) are simultaneously mixed and heat-treated to obtain absorbent resin particles. Production method. Based on the weight of the crosslinked polymer particles (A), the amount of water-insoluble spherical single particles (c) used is 0.01 to 1% by weight, and the amount of binder (d) used is 0.001 to 0.5% by weight. The manufacturing method according to claim 8 or 9. The production according to any one of claims 8 to 10, wherein the step (2) mixes the hydrophobic substance (e) with the mixing of the crosslinked polymer particles (A), the water-insoluble spherical single particles (c) and the binder (d). Method. The production method according to claim 11, wherein the amount of the hydrophobic substance (e) used is 0.001-1 based on the weight of the crosslinked polymer particles (A).

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