JP3648553B2 - Absorbent resin particles, absorbent body and absorbent article using the same - Google Patents

Description

The present invention relates to absorbent resin particles, an absorbent body using the same, and an absorbent article.

A cross-linked polymer having an increased absorption amount by a method of optimizing by changing the amount of polymerization initiator, polymerization temperature and polymerization concentration, or a method using a chain transfer agent such as thiol is known (Patent Document 1). In addition, many cross-linked polymers whose absorption amount under load is increased by a method of treating the vicinity of the surface of polymer particles have been proposed (Patent Documents 2 and 3, etc.). Moreover, the crosslinked polymer which improved the absorption rate by making a polymer particle porous is proposed (patent document 4 etc.).
JP-A-3-179008 Japanese Patent No. 267529 European Patent Publication No. 618005A JP 2002-212331 A

Absorbent articles (such as disposable diapers) that use conventional cross-linked polymers cause a decrease in the amount of absorbed liquid and the absorption speed when the user sits or lies down while wearing it. It was easy to cause problems such as more. And the absorbent article which does not have such problems, such as a mole, and the absorbent resin particle which can be used for this are strongly desired.
That is, an object of the present invention is to provide absorbent resin particles that exhibit high absorption performance (absorption amount and absorption rate) in any state and can be used for absorbent articles that are less likely to cause leakage. .

  As a result of intensive studies to achieve the above object, the present inventors have found that absorbent resin particles having a specific structure can solve the above problems, and have reached the present invention.

  That is, the characteristic of the absorbent resin particles of the present invention is that the water-soluble vinyl monomer (a1) and / or the vinyl monomer (a2) which becomes (a1) by hydrolysis and the internal crosslinking agent (b) are essential structural units. Absorbent resin particles comprising a polymer (A) and a hydrophobic substance (C), wherein the absorbent resin particles have a structure comprising part or all of (C) inside. The gist.

The absorbent resin particles of the present invention are remarkably excellent in the balance between the water retention performance (water retention amount) and the water-containing gel particles (the gel-like product formed by absorbing the absorbent resin particles) and the absorption time. Shows a light feel after absorption.
Therefore, when the absorbent resin particles of the present invention are applied to absorbent articles such as paper diapers and sanitary napkins, they exhibit excellent absorption performance (absorption amount and absorption rate) in any state and are less likely to cause leakage. An absorbent article is obtained. Furthermore, this absorbent article exhibits the characteristic that the liquid to be absorbed is unlikely to return in any state.

First, the crosslinked polymer (A) will be described.
The water-soluble vinyl monomer (a1) is not particularly limited, and a vinyl monomer having at least one water-soluble substituent and an ethylenically unsaturated group can be used.

Examples of the water-soluble substituent include a carboxyl (salt) group (—CO ₂ M), a sulfo (salt) group (—SO ₃ M), a group consisting of a sulfonate ester (salt) (sulfooxy (salt) group, —OSO ₃ M), a phosphono (salt) group (—PO (OM) ₂ ), a hydroxyl group (—OH), an amino group (—NR ₂ ), an amide group (carbamoyl group, —CONR ₂ ), an ammonio group (—NH ₃ · Y) and a secondary, tertiary or quaternary ammonio group (-NR ₃ · Y), and the like. Here, the carboxyl (salt) group is used to mean a group (metal carboxylate group or ammonium carboxylate group) comprising a carboxyl group or a carboxylate. The same is true for other groups.

M represents a hydrogen atom, an alkali metal (such as lithium, sodium and potassium) atom, an alkaline earth metal (such as magnesium and calcium) atom or ammonium (NH ₄ ), and R may include a hydrogen atom or a hetero atom. Good hydrocarbon group having 1 to 7 carbon atoms (such as methyl, ethyl, propyl, butyl, benzyl, hydroxyethyl, trifluoromethyl and chloroethyl), Y is a counter anion of ammonium cation (chlorine ion, bromine ion, methosulfate ion and Sulfate ion).

As the water-soluble vinyl monomer (a1), the following (i) anionic vinyl monomer, (ii) nonionic vinyl monomer and (iii) cationic vinyl monomer can be used.
(I) The anionic vinyl monomer may be a salt, and examples of the anionic vinyl monomer that is a salt include alkali metal salts (sodium salt and potassium salt), alkaline earth metal salts (calcium salt and magnesium salt). Etc.), ammonium salts [ammonium salts, tetraalkyl (alkyl group having 1 to 8 carbon atoms) ammonium salts (tetramethylammonium etc.), etc.], organic amine salts and the like. In addition, as organic amine salt which comprises organic amine salt, C1-C8 alkylamine, C2-C8 alkanolamine, polyalkylene (C1-C8 of alkylene) polyamine (2-10 amino groups) ) Or a derivative of polyalkylene polyamine [compound alkylated with an alkyl group having 1 to 8 carbon atoms, or a compound to which an alkylene oxide having 2 to 12 carbon atoms is added (average number of moles added per amino group is 1 to 1) 30 mol) and the like.

(I) Anionic vinyl monomer (i-1) As a vinyl monomer having a carboxyl (salt) group (—CO ₂ M), a vinyl group-containing carboxylic acid (salt) having 3 to 30 carbon atoms is used. Saturated monocarboxylic acids (such as (meth) acrylic acid, (meth) acrylates, crotonic acid and cinnamic acid); unsaturated dicarboxylic acids (such as maleic acid, maleate, fumaric acid, citraconic acid and itaconic acid); and Monoalkyl (carbon number 1 to 8) ester of unsaturated dicarboxylic acid (maleic acid monobutyl ester, fumaric acid monobutyl ester, maleic acid ethyl carbitol monoester, fumaric acid ethyl carbitol monoester, citraconic acid monoester Butyl ester and itaconic acid glycol monoester).

(I-2) As a vinyl monomer having a sulfo (salt) group (—SO ₃ M), a vinyl group-containing sulfonic acid (salt) having 2 to 30 carbon atoms or the like is used, and an aliphatic or aromatic vinyl sulfonic acid. (Vinyl sulfonic acid, (meth) allyl sulfonic acid, styrene sulfonic acid, α-methylstyrene sulfonic acid, etc.); (meth) acryloyl-containing alkyl sulfonic acid ((meth) acryloxypropyl sulfonic acid, 2-hydroxy-3- ( (Meth) acryloxypropylsulfonic acid, 2- (meth) acryloylamino-2,2-dimethylethanesulfonic acid, 3- (meth) acryloxyethanesulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid and 3- (meth) acrylamide-2-hydroxypropanesulfonic acid, etc.); and alkyl (3 to 1 carbon atoms) ) (Meth) allyl sulfosuccinate esters. In the present invention, for example, expressions such as (meth) acrylic ..., (meth) allyl ..., in the case of (meth) acrylic ..., represent acrylic ... or methacryl ..., (meth) allyl ... In the case of, it represents allyl · · or methallyl · ·.

(I-3) As a vinyl monomer having a group (sulfooxy group, —OSO ₃ M) comprising a sulfonic acid ester (salt), a sulfated product of hydroxyalkyl (having 2 to 6 carbon atoms) (meth) acrylate [hydroxyethyl (Meth) acrylate sulfate ester etc.]; poly (degree of polymerization 2 to 30) oxyalkylene (the number of carbon atoms of the alkylene group is 2 to 4, and the polymerization form is single or random and / or block) mono (meth) acrylate And the compounds represented by the general formula (5), (6) or (7), and the like. [Poly (polymerization degree 5-15) oxypropylene monomethacrylate sulfate ester etc.];

In general formulas (5) to (7), R represents a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. R ′ represents a hydrogen atom, an alkyl group having 1 to 15 carbon atoms which may be substituted with a fluorine atom, an alkali metal (lithium, sodium, potassium, etc.) atom, an alkaline earth metal (magnesium, calcium, etc.) atom or ammonium. Represent. OA represents an oxyalkylene group having 2 to 4 carbon atoms. When n is 2 or more, the 2 or more OA may be the same or different, and when they are different, they may be random, block, or a mixture thereof. Ar represents a benzene ring, and M represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, or ammonium. n represents an integer of 1 to 50.
Examples of the alkyl group include methyl, ethyl, propyl, t-butyl, 2-ethylhexyl, dodecanyl and pentadecanyl.
Examples of the alkyl group which may be substituted with a fluorine atom include methyl, ethyl, t-butyl, 2-ethylhexyl, pentadecanyl, trifluoromethyl and pentafluoroethyl.
Examples of the oxyalkylene group include oxyethylene, oxypropylene, and oxybutylene.

(I-4) As a vinyl monomer having a phosphono (salt) group (—PO (OM) ₂ ), a phosphoric acid monoester [(meth) acrylic acid of hydroxyalkyl (carbon number 2 to 6)] (meth) acrylate Hydroxyethyl monophosphate and the like], phosphoric acid diester (phenyl-2-acryloyloxyethyl phosphate and the like) of hydroxyalkyl (meth) acrylic acid (2 to 6 carbon atoms) and alkyl (meth) acrylate (2 to 2 carbon atoms) 6) Phosphonic acid [2-acryloyloxyethylphosphonic acid and the like] and the like.

(Ii) Nonionic vinyl monomer (ii-1) As the vinyl monomer having a hydroxyl group (—OH), monoethylenically unsaturated alcohol having 3 to 15 carbon atoms [(meth) allyl alcohol and (meth) propenyl alcohol, etc. And 2-6 valent polyols (C2-C20 alkylene glycol, glycerin, sorbitan, diglycerin, pentaerythritol, polyalkylene (C2-C4) glycol (weight average molecular weight 100-2000), etc.) A monoethylenically unsaturated carboxylic acid ester or a monoethylenically unsaturated ether is included.
Specific examples thereof include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, triethylene glycol (meth) acrylate, poly-oxyethylene-oxypropylene (random and / or block, weight average molecular weight 100 to 2000). Mono (meth) allyl ether (the terminal hydroxyl group is etherified or esterified with an alkyl group having 1 to 4 carbon atoms (such as methyl, ethyl and butyl) or a saturated fatty acid having 2 to 3 carbon atoms (such as acetic acid and propionic acid). May be included).

(Ii-2) Examples of vinyl monomers having a group consisting of amide (carbamoyl group, —CONR ₂ ) include (meth) acrylamide, N-alkyl (C 1-8) (meth) acrylamide [N-methylacrylamide, etc.] N, N-dialkyl (alkyl having 1 to 8 carbon atoms) acrylamide [N, N-dimethylacrylamide, N, N-di-n- or i-propylacrylamide and the like], N-hydroxyalkyl (1 to 8 carbon atoms) ) (Meth) acrylamide [N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, etc.]; N, N-dihydroxyalkyl (1 to 8 carbon atoms) (meth) acrylamide [N, N-dihydroxyethyl ( Meta) acrylamide etc.].
In addition to these, a vinyl lactam having 5 to 10 carbon atoms (N-vinylpyrrolidone or the like) can be used as the vinyl monomer having an amide group.

(Ii-3) As the vinyl monomer having an amino group (—NR ₂ ), an amino group-containing ester of a monoethylenically unsaturated mono- or dicarboxylic acid and a monoethylenically unsaturated mono- or dicarboxylic acid An amino group-containing amide can be used.
Examples of the amino group-containing ester of monoethylenically unsaturated mono- or di-carboxylic acid include dialkyl (alkyl having 1 to 8 carbon atoms) aminoalkyl (2 to 10 carbon atoms) (meth) acrylate, di (hydroxyalkyl) ( C1-C8) aminoalkyl (alkyl C2-C10) esters and morpholinoalkyl (C1-C8) esters can be used, such as dimethylaminoethyl (meth) acrylate, diethylamino (meth) acrylate, morpholinoethyl. (Meth) acrylate, dimethylaminoethyl fumarate, dimethylaminoethyl malate and the like can be mentioned.
As the amino group-containing amide of monoethylenically unsaturated mono- or di-carboxylic acid, monoalkyl (2 to 10 carbon atoms) (meth) acrylamide or the like is used, and dimethylaminoethyl (meth) acrylamide and diethylaminoethyl (meta) ) Acrylamide and the like.
In addition to these, vinyl pyridine (4-vinyl pyridine, 2-vinyl pyridine, etc.) can also be used as the vinyl monomer having an amino group.

(Iii) Cationic vinyl monomer (iii-1) A vinyl monomer having an ammonio group (—NH ₃ .Y) includes an ammonio group-containing ester of a monoethylenically unsaturated mono- or di-carboxylic acid [ammonioalkyl ( C2-C10) (meth) acrylate {ammonioethyl (meth) acrylate, chloride, etc.}] and monoethylenically unsaturated mono- or di-carboxylic acid-containing amide [ammonioalkyl (carbon number 2) To 10) (meth) acrylamide {ammonioethyl (meth) acrylamide / methosulphate etc.} and the like].

(Iii-2) As a vinyl monomer having a mono- or di-alkylammonio group (—NRH ₂ • Y or —NR ₂ H • Y), an alkylammoni of a monoethylenically unsaturated mono- or di-carboxylic acid O group-containing ester [monoalkyl (C1-4) ammonioalkyl (C2-10) (meth) acrylate {methylammonioethyl (meth) acrylate chloride and t-butylammonioethyl (meth) acrylate)・ Methosulfate etc.} and dialkyl (alkyl having 1 to 4 carbon atoms) ammonioalkyl (2 to 10 carbon atoms) (meth) acrylate {dimethylammonioethyl (meth) acrylate chloride and methyl t-butylammonioethyl ( Meth) acrylate, bromide, etc.}] and monoethylenically unsaturated mono Or an alkylammonio group-containing amide of di-carboxylic acid [monoalkyl (1 to 4 carbon atoms) ammonioalkyl (2 to 10 carbon atoms) (meth) acrylamide {methylammonioethyl (meth) acrylamide chloride and butylammoni Oethyl (meth) acrylamide chloride, etc.} and dialkyl (alkyl having 1 to 4 carbon atoms) ammonioalkyl (2 to 10 carbon atoms) (meth) acrylamide {dimethylammonioethyl (meth) acrylamide chloride and methylpropylammoni Oethyl (meth) acrylamide, methosulphate, etc.}.

(Iii-3) As a vinyl monomer having a trialkylammonio group (—NR ₃ · Y), the vinyl monomer having an amino group is an alkylating agent having 1 to 8 carbon atoms (methyl chloride, dimethyl sulfate, benzyl chloride). And quaternized with quaternizing agents such as dimethyl carbonate (trimethylammonioethyl (meth) acrylate / chloride, methyldiethylammonioethyl (meth) acrylate / methosulphate, trimethylammonioethylmalate / Chloride, trimethylammonioethyl (meth) acrylamide chloride, diethylbenzylammonioethyl (meth) acrylamide chloride} and the like. In addition to these, N-vinylpyridinium salts (N-vinylpyridinium chloride, N-methyl-2-vinylpyridinium chloride, etc.) can also be used.

10-20 are preferable, as for the HLB value of a water-soluble vinyl monomer, More preferably, it is 11.5-20, Most preferably, it is 13-20.
In the present invention, the HLB value is the value of Davis's HLB (Takehiko Fujimoto, “Introduction to New Surfactant”, Sanyo Kasei Kogyo Co., Ltd., August 1992, 3rd edition, page 132; Takehiko Fujimoto, “New Introduction to Surface Active Agents”, Copyright 1985, SANYO CHEMICAL INDUSTRIES, LTD, p. 132).

The vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis is not particularly limited, but a vinyl monomer having at least one hydrolyzable substituent which becomes a water-soluble substituent by hydrolysis is used. it can.
Examples of the hydrolyzable substituent include a group containing an acid anhydride (1,3-oxo-1-oxapropylene group, —COO—CO—), a group containing an ester bond (alkyloxycarbonyl, vinyloxycarbonyl, allyloxy). Carbonyl or propenyloxycarbonyl, -COOR) and a cyano group.
R is an alkyl group having 1 to 3 carbon atoms (methyl, ethyl and propyl), vinyl, allyl and propenyl.

Examples of the vinyl monomer having a group containing an acid anhydride include dicarboxylic acid anhydrides having 4 to 20 carbon atoms, and examples thereof include maleic anhydride, itaconic anhydride, and citraconic anhydride.
Examples of vinyl monomers having a group containing an ester include lower alkyl (carbon number 1 to 3) esters of monoethylenically unsaturated carboxylic acid (such as methyl (meth) acrylate and ethyl (meth) acrylate), monoethylenically unsaturated monomers. Examples thereof include esters of saturated alcohol [vinyl acetate, (meth) allyl acetate, etc.].
As a vinyl monomer which has a cyano group, a C3-C6 vinyl group containing nitrile compound etc. [(meth) acrylonitrile, 5-hexene nitrile, etc.] etc. are mentioned.

Hydrolysis of the hydrolyzable substituent may be performed either during polymerization, after polymerization, or both of them, but is preferably after polymerization from the viewpoint of the molecular weight of the resulting crosslinked polymer.
When either vinyl monomer (a1) or (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.
Of these, the water-soluble vinyl monomer (a1) is preferred, more preferably an anionic vinyl monomer, particularly preferably a carboxyl (salt) group, a sulfo (salt) group, an amino group, a group consisting of an amide, an ammonio group or a mono- , Vinyl monomers having a di- or tri-alkylammonio group, then preferably vinyl monomers having a carboxyl (salt) group or a group comprising an amide, more particularly preferably (meth) acrylic acid (salt) and ( Meth) acrylamide, more particularly preferably (meth) acrylic acid (salt), and most preferably acrylic acid (salt).

When the water-soluble vinyl monomer (a1) and the vinyl monomer (a2) are used as structural units, the content weight ratio (a1 / a2) is preferably 75/25 to 99/1, and more preferably 85/15 to 95. / 5, particularly preferably 90/10 to 93/7, most preferably 91/9 to 92/8. Within this range, the absorption performance (especially the absorption amount and the absorption rate) is further improved.

As the vinyl monomer used as the structural unit of the crosslinked polymer (A), in addition to the vinyl monomer (a1) and / or (a2), another vinyl monomer (a3) copolymerizable with these can be used as the structural unit. It can be.
Examples of other copolymerizable vinyl monomers (a3) include hydrophobic vinyl monomers, but are not limited thereto.
As the other vinyl monomer (a3), the following vinyl monomers (i) to (iii) are used.

(I) an aromatic ethylenic monomer having 8 to 30 carbon atoms;
Styrene such as styrene, α-methylstyrene, vinyltoluene and hydroxystyrene, and halogen substituted products of styrene such as vinylnaphthalene and dichlorostyrene.
(Ii) an aliphatic ethylene monomer having 2 to 20 carbon atoms;
Alkenes [ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.]; and alkadienes [butadiene, isoprene, etc.] and the like.
(Iii) an alicyclic ethylene monomer having 5 to 15 carbon atoms;
Monoethylenically unsaturated monomers [such as pinene, limonene and indene]; and polyethylene-based vinyl polymerizable monomers [such as cyclopentadiene, bicyclopentadiene and ethylidene norbornene].

  When the other copolymerizable vinyl monomer (a3) is used as a structural unit, the content (% by weight) of (a3) is 0.01 to based on the total weight of the vinyl monomers (a1) and (a2). 5, more preferably 0.05 to 3, particularly preferably 0.08 to 2, and most preferably 0.1 to 1.5. Within this range, the absorption performance (especially the absorption amount and the absorption rate) is further improved.

  As the internal cross-linking agent (b), an internal cross-linking agent (b1) having two or more ethylenically unsaturated groups, a water-soluble substituent of the water-soluble vinyl monomer (a1) and / or a hydrolysis of the vinyl monomer (a2). Internal cross-linking agent (b2) having at least one functional group capable of reacting with the water-soluble substituent to be generated and having at least one ethylenically unsaturated group, and water-soluble substitution of water-soluble vinyl monomer (a1) An internal cross-linking agent (b3) having at least two functional groups capable of reacting with a water-soluble substituent formed by hydrolysis of the group and / or vinyl monomer (a2) can be used.

  (I) As an internal crosslinking agent (b1) having two or more ethylenically unsaturated groups, bis (meth) acrylamide having 8 to 12 carbon atoms, poly (meth) acrylate of a polyol having 2 to 10 carbon atoms, carbon number A poly (meth) allyl ether of 2 to 10 polyallylamine and a polyol having 2 to 10 carbon atoms is used, and N, N′-methylenebis (meth) acrylamide, ethylene glycol di (meth) acrylate, poly (degree of polymerization 2) -5) ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, glycerin (di or tri) acrylate, trimethylolpropane triacrylate, diallylamine, triallylamine, triallyl cyanurate, triallyl isocyanurate, tetraary Roxyethane, pentaerythrito Dialdiallyl ether, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, and diglycerin di (meth) acrylate.

(Ii) having at least one functional group capable of reacting with the water-soluble substituent of the water-soluble vinyl monomer (a1) and / or the water-soluble substituent generated by hydrolysis of the vinyl monomer (a2) and having at least one Examples of the internal crosslinking agent (b2) having an ethylenically unsaturated group include an ethylenically unsaturated compound having an epoxy group having 6 to 8 carbon atoms, an ethylenically unsaturated compound having a hydroxyl group having 4 to 8 carbon atoms, and the number of carbon atoms. Ethylenically unsaturated compounds having 4 to 8 isocyanato groups are used, and specific examples thereof include glycidyl (meth) acrylate, N-methylol (meth) acrylamide, hydroxyethyl (meth) acrylate and isocyanatoethyl ( And (meth) acrylate.

(Iii) Internal cross-linking agent having at least two functional groups capable of reacting with water-soluble substituents of water-soluble vinyl monomer (a1) and / or water-soluble substituents generated by hydrolysis of vinyl monomer (a2) ( b3) include polyhydric alcohols, polyglycols, polyamines, polyaziridines and polyisocyanates described in JP-A-58-180233 (corresponding to US Pat. No. 4,666,983) and JP-A-59-189103. Etc. can be used. Examples of the polyvalent glycidyl compound include ethylene glycol diglycidyl ether and glycerin diglycidyl ether. Examples of the polyvalent amine compound include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and polyethyleneimine. As a polyvalent aziridine compound, trade name: Chemitite PZ-33 {2,2-bishydroxymethylbutanol-tris (3- (1-aziridinyl) propionate)}, trade name: Chemitite HZ-22 {1,6-hexa Methylenediethylene urea} and trade name: Chemite DZ-22 {diphenylmethane-bis-4, 4′-N, N′-diethylene urea} (these are trade names manufactured by Nippon Shokubai Chemical Industry Co., Ltd.). Examples of the polyvalent isocyanate compound include 2,4-tolylene diisocyanate and hexamethylene diisocyanate.
These internal crosslinking agents may be used alone or in combination of two or more.

  Among the internal cross-linking agents (b), from the viewpoint of absorption performance (particularly absorption amount and absorption rate), the internal cross-linking agent (b1) having two or more ethylenically unsaturated groups is preferable, and more preferably 2 carbon atoms. Poly (meth) allyl ethers of 10 to 10 polyols, particularly preferably triallyl cyanurate, triallyl isocyanurate, tetraallyloxyethane and pentaerythritol triallyl ether, most preferably pentaerythritol triallyl ether.

  The content (% by weight) of the internal crosslinking agent (b) is 0.001 to 5 based on the total weight of the vinyl monomers (a1) and / or (a2) and other vinyl monomers (a3) used as necessary. Is more preferable, 0.002 to 2 is more preferable, and 0.003 to 1.6 is particularly preferable. Within this range, the absorption performance (especially the absorption amount and the absorption rate) is further improved.

The crosslinked polymer (A) is further added with additives described later {preservatives, fungicides, antibacterial agents, antioxidants, ultraviolet absorbers, colorants, fragrances, deodorants, organic fibrous materials, etc.}. It can be contained if necessary.
When these additives are contained, the content (% by weight) of the additives is preferably 0.001 to 10, more preferably 0.01 to 5, particularly preferably based on the weight of the crosslinked polymer (A). Preferably it is 0.05 to 1, most preferably 0.1 to 0.5.

As a polymerization form of the crosslinked polymer (A), a conventionally known method can be used, and a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a reverse phase suspension polymerization method can be applied. Further, the shape of the polymerization solution at the time of polymerization may be a thin film shape, a spray shape, or the like. As a polymerization control method, an adiabatic polymerization method, a temperature control polymerization method, an isothermal polymerization method, or the like can be applied.
When applying the suspension polymerization method or the reverse phase suspension polymerization method as the polymerization method, conventionally known dispersants (such as sucrose ester, phosphate ester and sorbitan ester) and protective colloid (Poval, α) -Olefin-maleic anhydride copolymer, polyethylene oxide, etc.) can be used. In the case of the reverse phase suspension polymerization method, the polymerization can be carried out using a conventionally known solvent such as cyclohexane, normal hexane, normal heptane, toluene and xylene.
Among the polymerization methods, the solution polymerization method is preferable, and an aqueous solution polymerization method is particularly preferable because it is not necessary to use an organic solvent and is advantageous in terms of production cost.

A polymerization initiator can be used for the polymerization of the crosslinked polymer (A). The polymerization initiator is not particularly limited and conventionally known ones can be used. (I) An azo initiator, (ii) a peroxide initiator, (iii) a redox initiator, and (iv) an organic halogen compound start An agent etc. can be used.
(I) As the azo initiator, azobisisobutyronitrile, azobiscyanovaleric acid and its salt, 2,2'-azobis (2-amidinopropane) hydrochloride and 2,2'-azobis (2-methyl-) N- (2-hydroxyethyl) propionamide and the like can be mentioned.
(Ii) Peroxide initiators include inorganic peroxides [hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, etc.], organic peroxides [benzoyl peroxide, di-t-butyl peroxide] , Cumene hydroperoxide, succinic acid peroxide, di (2-ethoxyethyl) peroxydicarbonate, and the like].

(Iii) As the redox initiator, at least one reducing agent such as alkali metal sulfite, alkali metal bisulfite, ammonium sulfite, ammonium bisulfite, ferric chloride, ferric sulfate, and ascorbic acid; Examples thereof include those comprising a combination of at least one oxidizing agent such as alkali metal persulfate, ammonium persulfate, hydrogen peroxide and organic peroxide.
(Iv) As an organic halogen compound initiator, 1 to 10 halogen atoms, 1 to 1 carbon atoms selected from the group consisting of alkyl halides, halogenated alkylphenyl ketones, halogenated alkylcarboxylic acids and halogenated alkylcarboxylic acid alkyl esters 15 organic halogen compounds are used, and tetrachloromethane, trichlorobromomethane, trichloroiodomethane, dichloromethylphenylketone, 1-bromo-1-methylethylcarboxylic acid, and alkyl group having 1 to 12 carbon atoms 1-bromo. -1-methylethylcarboxylic acid alkyl esters (methyl 1-bromo-1-methylethylcarboxylate, ethyl 1-bromo-1-methylethylcarboxylate, octyl 1-bromo-1-methylethylcarboxylate and 1-bromo- 1-methylethylcarboxylic acid Glycoluril), and the like.

  Of these, (i) azo initiators, (ii) peroxide initiators, or (iii) redox initiators are preferred, and (i) azo initiators or (ii) peroxide initiators are more preferred. And (iii) redox initiator.

  When a polymerization initiator is used, the amount (% by weight) of the polymerization initiator used is as follows: vinyl monomer (a1) and / or (a2), other vinyl monomer (a3) used if necessary, and internal crosslinking agent (b) Is preferably 0.005 to 0.5, more preferably 0.007 to 0.4, and particularly preferably 0.009 to 0.3.

  In the polymerization of the crosslinked polymer (A), the hydrophobic substance (C) or the material (D) described later is replaced with the vinyl monomer (a1) and / or (a2), (a3) and (b), or a solvent. The polymer may be dissolved or dispersed in the polymer.

The hydrogel {including the crosslinked polymer (A) and water} obtained by polymerization can be crushed as necessary. The size (longest diameter) of the hydrogel after 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 crushing can be performed by a known method, and for example, the crushing can be performed using a normal apparatus such as a Bex mill, a rubber chopper, a pharma mill, a mincing machine, an impact crusher, and a roll crusher.

When using a solvent (including water) for the polymerization of the crosslinked polymer (A), the solvent can be distilled off after the polymerization.
When the solvent contains an organic solvent, the content (% by weight) of the organic solvent after distillation is preferably from 10 to 0.01, more preferably from 5 to 0. 0, based on the weight of the crosslinked polymer (A). 05, particularly preferably 3 to 0.1, most preferably 1 to 0.5. Within this range, the absorption performance (particularly the water retention amount) of the absorbent resin particles is further improved.
Moreover, when water is included in the solvent, the water content (% by weight) after the distillation is preferably 0 to 20, more preferably 0 to 10, particularly preferably 0 to 0, based on the weight of the crosslinked polymer (A). 5, most preferably 0-2. Within this range, the absorption performance (particularly the water retention amount) and the handling properties after drying (such as the powder flowability of the crosslinked polymer particles) are further improved.
In addition, the content and water content of the organic solvent are an infrared moisture measuring device (JE400 manufactured by KETT Co., Ltd.): 120 ± 5 ° C., 30 minutes, atmospheric humidity before heating 50 ± 10% RH, lamp specification 100V, 40W ) Is obtained from the weight loss of the crosslinked polymer (A) before and after heating.
The method of distilling off the solvent is a method of distilling (drying) with hot air at a temperature of 80 to 230 ° C., a thin film drying method using a drum dryer or the like heated to 100 to 230 ° C., (heating) vacuum drying method, freeze drying Ordinary methods such as a method, a drying method using infrared rays, decantation and filtration may be used.

Furthermore, the crosslinked polymer (A) can be pulverized after drying.
In the case of pulverization, the weight average particle size (μm) of the crosslinked polymer after pulverization is preferably 100 to 800, more preferably 200 to 500, and particularly preferably 300 to 400. Within this range, handling properties after pulverization (powder fluidity of crosslinked polymer particles, etc.) are further improved.

The weight average particle size is plotted on a logarithmic probability paper with the particle size distribution of the crosslinked polymer as the particle size on the horizontal axis and the content on the vertical axis on the weight basis. It depends on how you ask.
The particle size distribution was measured in accordance with JIS Z8815-1994, and 710 μm, 500 μm, 300 μm, 150 μm, and 106 μm aperture sieves having an inner diameter of 150 mm and a depth of 45 mm were stacked on top of each other with a narrow aperture sieve. Place 50 g of the measurement sample on the 710 μm sieve with the widest opening at the top, sieve for 10 minutes with a sieve vibrator, and measure the weight of the measurement sample remaining on each sieve. It is measured by determining the weight percent of the measurement sample remaining on each sieve based on weight.

The smaller the content of fine particles, the better the absorption performance, and the content of fine particles of 106 μm or less in the total particles is preferably 3% by weight or less, more preferably the content of fine particles of 150 μm or less in the total particles is 3% by weight. It is as follows.
The content of the fine particles can be obtained by using a plot created when obtaining the above weight average particle diameter.

The pulverization method is not particularly limited, and usual devices such as a hammer pulverizer, an impact pulverizer, a roll pulverizer, and a shet airflow pulverizer can be used.
The obtained pulverized product is sieved as necessary to adjust the particle size.
The shape of the crosslinked polymer 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 the fibrous material for use in paper diapers and the like and no fear of dropping off from the fibrous material, an irregular crushed shape is preferable.

  The hydrophobic substance (C) includes a hydrophobic substance (C1) containing a hydrocarbon group, a hydrophobic substance (C2) containing a hydrocarbon group having a fluorine atom, and a hydrophobic substance (C3) having a polysiloxane structure. Etc. can be used. Of these, the hydrophobic substance (C3) having a polysiloxane structure is preferable from the viewpoint of the anti-moisture resistance of the absorbent article.

  Examples of the hydrophobic substance (C1) containing a hydrocarbon group include polyolefin resins, polyolefin resin derivatives, polystyrene resins, polystyrene resin derivatives, waxes, long chain fatty acid ester resins, long chain fatty acids, and mixtures of two or more thereof. included.

  As the polyolefin resin, a weight average comprising an olefin having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene or isoprene as an essential constituent monomer (the olefin content is at least 50% by weight based on the weight of the polyolefin resin). A polymer having a molecular weight of 1,000 to 1,000,000 can be used, and examples thereof include polyethylene, polypropylene, polyisobutylene, poly (ethylene-isobutylene), and isoprene.

  As the polyolefin resin derivative, a polymer having a weight average molecular weight of 1,000 to 1,000,000 (acid-modified polyolefin resin) obtained by introducing a carboxyl group (—COOH), 1,3-oxo-2-oxapropylene (—COOCO—), or the like into the polyolefin resin. Polyethylene thermal degradation product, polypropylene thermal degradation product, maleic acid modified polyethylene, chlorinated polyethylene, maleic acid modified polypropylene, ethylene-acrylic acid copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride Examples thereof include acid copolymers, maleated polybutadiene, ethylene-vinyl acetate copolymers, and maleated products of ethylene-vinyl acetate copolymers. In the case of a copolymer with ethylene or butylene, the content of ethylene or butylene is preferably 60 to 99.9 mol% based on the number of moles of the constituent monomers.

As the polystyrene, 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 as styrene as an essential monomer (the content of styrene is at least 50% by weight based on the weight of the polystyrene derivative) can be used. -Maleic anhydride copolymer, styrene-butadiene copolymer, styrene-isobutylene copolymer and the like.

  As the wax, a wax having a melting point of 50 to 200 ° C. can be used, and examples thereof include paraffin wax, beeswax, carbana wax, and beef tallow.

  As long-chain fatty acid esters, esters of fatty acids having 8 to 25 carbon atoms and alcohols having 1 to 5 carbon atoms can be used, such as methyl laurate, ethyl laurate, methyl stearate, ethyl stearate, methyl oleate, Ethyl oleate, glycerol laurate monoester, glycerol stearate monoester, glycerol oleate monoester, pentaerythritol laurate monoester, pentaerythritol stearate monoester, pentaerythritol oleate monoester, sorbit laurate monoester Examples thereof include esters, sorbite stearic acid monoester, sorbite oleic acid monoester, and beef tallow.

  As the long chain fatty acid, a fatty acid having 8 to 25 carbon atoms can be used, and examples thereof include lauric acid, stearic acid, oleic acid, dimer acid, and behenic acid.

  Of the hydrophobic substance (C1) containing a hydrocarbon group, a polyolefin resin, a wax, and a long-chain fatty acid ester are preferable, more preferably a polyolefin resin and a wax, particularly preferably, from the viewpoint of the moisture resistance of the absorbent article. Wax, most preferably paraffin wax.

  Examples of the hydrophobic substance (C2) containing a hydrocarbon group having a fluorine atom include perfluoroalkane, perfluoroalkene, perfluoroaryl, perfluoroalkyl ether, perfluoroalkyl carboxylic acid, perfluoroalkyl alcohol, and those 2 A mixture of seeds or more is included.

  As perfluoroalkanes, alkanes having 4 to 42 fluorine atoms and 1 to 20 carbon atoms can be used. Trifluoromethane, pentafluoroethane, pentafluoropropane, heptafluoropropane, heptafluorobutane, nonafluorohexane, trideca Examples include fluorooctane and heptadecafluorododecane.

  As the perfluoroalkene, alkene having 4 to 42 fluorine atoms and 2 to 20 carbon atoms can be used, and trifluoroethylene, pentafluoropropene, trifluoropropene, heptafluorobutene, nonafluorohexene, tridecafluorooctene and Heptadecafluorododecene and the like can be mentioned.

  As perfluoroaryl, aryl having 4 to 42 fluorine atoms and 6 to 20 carbon atoms can be used. Trifluorobenzene, pentafluorotoluene, trifluoronaphthalene, heptafluorobenzene, nonafluoroxylene, tridecafluorooctylbenzene And heptadecafluorododecylbenzene.

  As perfluoroalkyl ether compounds, ethers having 2 to 82 fluorine atoms and 2 to 40 carbon atoms can be used, such as ditrifluoromethyl ether, dipentafluoroethyl ether, dipentafluoropropyl ether, diheptafluoropropyl ether, Examples include diheptafluorobutyl ether, dinonafluorohexyl ether, ditridecafluorooctyl ether, and diheptadecafluorododecyl ether.

  As the perfluoroalkyl carboxylic acid, carboxylic acid having 3 to 41 fluorine atoms and 1 to 21 carbon atoms can be used, such as pentafluoroethanoic acid, pentafluoropropanoic acid, heptafluoropropanoic acid, heptafluorobutanoic acid, nonafluoro. Examples include hexanoic acid, tridecafluorooctanoic acid, heptadecafluorododecanoic acid, and salts of these metals (such as alkali metals and alkaline earth metals).

  As the perfluoroalkyl alcohol, alcohol having 3 to 41 fluorine atoms and 1 to 20 carbon atoms can be used, such as pentafluoroethanol, pentafluoropropanol, heptafluoropropanol, heptafluorobutanol, nonafluorohexanol, and tridecafluorooctanol. And heptadecafluorododecanol and the like, and besides these, these ethylene oxide (1 to 20) adducts and the like can be mentioned.

  Of the hydrophobic substance (C2) containing a hydrocarbon group having a fluorine atom, perfluoroalkyl ether, perfluoroalkyl carboxylic acid and perfluoroalkyl alcohol are preferable from the viewpoint of the anti-moisture resistance of the absorbent article. Preferred are perfluoroalkyl ethers and perfluoroalkyl carboxylic acids, particularly preferred are perfluoroalkyl carboxylic acids, and most preferred are pentafluoropropanoic acid.

As the hydrophobic substance (C3) having a polysiloxane structure, silicone and modified silicone can be used. Polydimethylsiloxane, polyether modified polysiloxane {polyoxyethylene modified polysiloxane and poly (oxyethylene oxypropylene) modified poly Siloxane etc.}, carboxyl-modified polysiloxane, epoxy-modified polysiloxane, amino-modified polysiloxane, alkoxy-modified polysiloxane and the like, and mixtures thereof.
Of the hydrophobic substance (C3) having a polysiloxane structure, silicones and modified silicones are preferable from the viewpoint of the anti-moisture resistance of the absorbent article, etc., then preferably modified silicones, more preferably polyether-modified polysiloxanes, amino acids. Modified polysiloxanes and carboxyl-modified polysiloxanes, particularly preferably polyether-modified polysiloxanes and amino-modified polysiloxanes, most preferably amino-modified polysiloxanes.

  When using the modified silicone, the position for introducing the organic group (modified group) is not particularly limited, but the side chain of the polysiloxane, both ends of the polysiloxane, one end of the polysiloxane, the side chain of the polysiloxane Either of both ends may be used. Of these, from the viewpoint of the anti-moisture resistance of the absorbent article, both the polysiloxane side chain and the polysiloxane side chain and both ends are preferred, and more preferably both the polysiloxane side chain and both ends. It is.

  Examples of the organic group (modified group) of the polyether-modified polysiloxane include a group containing a polyoxyethylene group and 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 moisture resistance of the absorbent article is 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 moisture resistance of the absorbent article is further improved.

The organic group (modified group) of the carboxyl-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 (KOHmg / g) of these modified silicones is preferably 400 to 10,000, more preferably 600 to 5,000, particularly preferably 800 to 3,000 as carboxy equivalent, epoxy equivalent or amino equivalent. , And most preferably 1000-1500. That is, the lower limit of the organic group content (KOHmg / g) of these modified silicones is preferably 400, more preferably 600, particularly preferably 800, most preferably 1000, as carboxy equivalent, epoxy equivalent or amino equivalent. Similarly, the upper limit is preferably 10,000, more preferably 5000, particularly preferably 3000, and most preferably 1500. Within this range, the moisture resistance of the absorbent article is further improved.

  Examples of the organic group (modified group) of the alkoxy-modified polysiloxane include alkoxy groups such as methoxy, ethoxy, butoxy, octyloxy, undodecyloxy, hexadecyloxy, and octadecyloxy. As carbon number of an alkoxy group, 1-40 are preferable, More preferably, it is 5-30, Most preferably, it is 10-20, Most preferably, it is 12-18. Within this range, the moisture resistance of the absorbent article is further improved.

  The viscosity (mPa · s) at 25 ° C. of the hydrophobic substance (C) is preferably 10 to 2,000, more preferably 15 to 1,500, and particularly preferably 20 to 1000. That is, the lower limit of the viscosity (mPa · s) at 25 ° C. of the hydrophobic substance (C) is preferably 10, more preferably 15, particularly preferably 20, and similarly the upper limit is preferably 2,000. It is preferably 1,500, particularly preferably 1000. Within this range, the moisture resistance of the absorbent article is further improved.

  The HLB value of the hydrophobic substance (C) is preferably 1 to 10, more preferably 2 to 8, particularly preferably 3 to 6. That is, the lower limit of the HLB value of (C) is preferably 1, more preferably 2, particularly preferably 3, and similarly the upper limit is preferably 10, more preferably 8, particularly preferably 6. Within this range, the moisture resistance of the absorbent article is further improved.

  The content (% by weight) of the hydrophobic substance (C) is preferably 0.001 to 3, more preferably 0.005 to 2, particularly preferably 0.07, based on the weight of the crosslinked polymer (A). ~ 1.5, most preferably 0.1-1. That is, the lower limit of the content (% by weight) of (C) is preferably 0.001, more preferably 0.005, particularly preferably 0.07, and most preferably 0.00, based on the weight of (A). 1 and similarly, the upper limit is preferably 3, more preferably 2, particularly preferably 1.5, and most preferably 1. Within this range, the absorption amount under diffusion and the water retention amount are further improved.

  If the absorbent resin particle of the present invention has a structure comprising part or all of the hydrophobic substance (C) inside the absorbent resin particle, how the hydrophobic substance (C) is contained. It does not matter. However, the structure including part or all of the hydrophobic substance (C) inside the absorbent resin particles includes (1) the connecting portion (RC) made of (C) inside the absorbent resin particles. Or (2) the inside of the absorbent resin particles with the material (D) coated or impregnated with the hydrophobic substance (C) on part or all of the surface of the hydrophilic material (d1) or the hydrophobic material (d2) The structure comprising is preferred.

(1) The structure including the connecting portion (RC) made of (C) inside the absorbent resin particles will be described.
The connecting portion (RC) is a sandwich composed of (A)-(C)-(A) formed by contacting at least half the total surface area of the hydrophobic substance (C) with the crosslinked polymer (A). Means structure.
When the hydrophobic substance (C) is present only on the surface of the absorbent resin particles, a two-layer structure consisting of (A)-(C) is formed, but consisting of (A)-(C)-(A). It does not have a sandwich structure. That is, such a two-layer structure is not included in the connecting portion (RC) in the present invention.
Therefore, the structure including the connecting portion (RC) inside the absorbent resin particle is a structure in which this sandwich structure {(A)-(C)-(A)} is present inside the absorbent resin particle. means.
The hydrophobic substance (C) is preferably also present on a part of the surface of the absorbent resin particle, more preferably (C) is present on the surface of the absorbent resin particle, C) and (C) inside the absorbent resin particles are continuously connected.

The shape of the connecting portion (RC) is not particularly limited, but from the viewpoint of the anti-moisture resistance of the absorbent article, a layered shape, a planar shape, a rod shape, a tubular shape, a spherical shape, a mesh shape, and combinations thereof are preferable, and more preferably Layered and planar, more preferably layered. The size of the continuous part (RC) (longest part: unit μm) preferably includes 10 to 1000 linear parts, more preferably 50 to 800, particularly preferably 100 to 700, and most preferably 200 to 600. Is included. Within this range, the moisture resistance of the absorbent article is further improved.
The shape and the size of the continuous part (RC) are the same as those of the hydrophobic substance (C2) in which the hydrophobic substance (C) contains a hydrocarbon group having a fluorine atom and / or the hydrophobic substance (C3) having a polysiloxane structure. In this case, for example, measurement can be performed by mapping fluorine atoms and / or silicon atoms with an electron microanalyzer (EPMA) (for example, JXA-8621MX manufactured by JEOL Ltd.). When the hydrophobic substance (C) is a hydrophobic substance (C1) containing a hydrocarbon group, the absorbent resin particles of the present invention are cut with a microtome and cut with a nonpolar solvent such as hexane and / or dimethyl ether. After washing the cross section, it can be measured by observing with a SEM (scanning electron microscope).

  When the absorbent resin particles have a structure including a connecting portion (RC), the absorbent resin particles are (1) formed with the connecting portion (RC) and then mixed with the crosslinked polymer (A). It can be manufactured by a method, or (2) a method of forming the connecting portion (RC) while manufacturing (A).

In the method (1), the connecting portion (RC) can be formed by processing the hydrophobic substance (C) into a pulverized product, bead, rod or fiber. The weight average particle size (μm) of the pulverized film is preferably 20 to 1000, more preferably 50 to 500, and particularly preferably 100 to 400. The weight average particle diameter (μm) of the beads is preferably 0.5 to 100, more preferably 2 to 300, and particularly preferably 5 to 100. The rod-like length (μm) is preferably 20 to 1000, more preferably 50 to 500, particularly preferably 100 to 400, and the diameter (μm) is preferably 0.5 to 50, more preferably 1 to 30. Especially preferably, it is 2-15. The fibrous length (μm) is preferably 20 to 1000, more preferably 50 to 500, particularly preferably 100 to 400, and the diameter (μm) is preferably 0.5 to 50, more preferably 1 -30, particularly preferably 2-15. Within these ranges, the moisture resistance of the absorbent article is further improved.

Examples of the connecting part (RC1) made of the hydrophobic substance (C1) containing a hydrocarbon group include beads such as polystyrene beads and polyethylene beads, and polyethylene films (for example, SE625M, UB-1 manufactured by Tamapoly) and polystyrene films. (For example, Asahi Kasei Co., Ltd. product: OPS etc.) The pulverized product (weight average particle size 20-1000 micrometers) etc. of a film etc. are mentioned. As the connection part (RC3) made of the hydrophobic substance (C3) containing polysiloxane, silicone beads {for example, GE Toshiba Silicones Co., Ltd .: Tospearl 240 (amorphous silicone resin fine powder, weight average particle diameter 4 μm), Tospearl 3120 (true spherical silicone resin fine powder, weight average particle diameter 12 μm), Tospearl 145 (true spherical silicone resin fine powder, weight average particle diameter 4.5 μm), etc.}. As the connection part (RC2) made of a hydrophobic substance (C2) containing a hydrocarbon group having a fluorine atom, a fluorine film {eg, Asahi Glass Co., Ltd .: FLUON PTFE (polytetrafluoroethylene film), FLUON PFA (four A film of a copolymer of ethylene fluoride and perfluoroethylene), FLUON AFLAS (a film of a copolymer of tetrafluoroethylene and propylene), etc.} (weight average particle diameter 20 to 1000 μm), etc. .
Among these, from the viewpoint of the anti-absorption property of the absorbent article, a crushed film is preferable, and a crushed fluorine film is more preferable.

As a method of mixing the crosslinked polymer (A) and the connecting portion (RC), the hydrophobic substance (C) is present in the crosslinked polymer (A) {that is, the crosslinked polymer (A) and the hydrophobic portion (C) are hydrophobic. There is no limitation as long as the substance (C) is mixed so as to have a sandwich structure.
However, the connecting portion (RC) is preferably not mixed with the dried polymer of the cross-linked polymer (A), but mixed with the hydrogel of (A) or the polymerization liquid of (A), and more preferably the hydrous of (A). To be mixed with the gel. In addition, it is preferable to mix uniformly so that mixing may be carried out.
When the crosslinked polymer (A) is obtained by the aqueous solution polymerization method, the timing of mixing and kneading the connecting portion (RC) and (A) is not particularly limited, but during the polymerization process, immediately after the polymerization process, the hydrogel is crushed. (Minced) and during drying of the hydrogel. Among these, from the viewpoint of the anti-moisture resistance of the absorbent article, it is preferable to be immediately after the polymerization process and during the hydrogel crushing (mincing) process, and more preferably during the hydrogel crushing (mincing) process.

  When the crosslinked polymer (A) is obtained by the reverse phase suspension polymerization method or emulsion polymerization, the timing of mixing the connecting portion (RC) and (A) is not particularly limited, but during the polymerization step {(A) Forming the connecting part (RC) while producing}, immediately after the polymerization process, during the dehydration process (during the process of dehydrating to about 10% by weight of water), immediately after the dehydration process, during the process of separating and distilling the organic solvent used for the polymerization And during the drying of the hydrogel. Among these, from the viewpoint of the anti-moisture resistance of the absorbent article, it is preferable during the polymerization step, immediately after the polymerization step, during the dehydration step, immediately after the dehydration step, and during the step of separating and distilling off the organic solvent used for the polymerization. Is immediately after the polymerization step during the polymerization step.

  In the case of mixing during the drying of the hydrogel, a normal apparatus such as a bex mill, rubber chopper, pharma mill, mincing machine, impact pulverizer, and roll pulverizer can be used. When mixing 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 in drying of a hydrogel, kneading apparatuses, such as SV mixer, can also be used.

(2) In the method of forming the connecting part (RC) while producing the crosslinked polymer (A), the connecting part (RC) is formed by polymerizing (A) in the presence of the hydrophobic substance (C). Is done. Further, the hydrophobic substance (C) is dissolved or emulsified (dispersed) in the polymer solution of the crosslinked polymer (A), and the connecting portion is formed while (C) is precipitated as the polymerization of (A) proceeds. You can also.

The hydrophobic substance (C) can be used in a form dissolved and / or emulsified in water and / or a volatile solvent (however, no emulsifier is used). As the volatile solvent, those having a vapor pressure (Pa) at 20 ° C. of 0.13 to 5.3 are preferable, more preferably 0.15 to 4.5, and particularly preferably, from the viewpoint of easy removal. Is from 0.23 to 3.8.
Examples of the volatile solvent 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 and the like), ketones having 3 to 4 carbon atoms (such as acetone and methyl ethyl ketone), and esters having 3 to 5 carbon atoms (such as ethyl formate, ethyl acetate, isopropyl acetate and diethyl carbonate). When water and / or a volatile solvent is used, the amount (% by weight) of these used is preferably 1 to 900, more preferably 5 to 700, particularly preferably based on the weight of the hydrophobic substance (C). 10-400. When water and a volatile solvent are used, the amount (% by weight) of water used is preferably 50 to 98, more preferably 60 to 95, particularly preferably 70 to 90, based on the weight of water and the volatile solvent. It is.

(2) A material (D) obtained by coating or impregnating a hydrophobic substance (C) on part or all of the surface of the hydrophilic material (d) or the hydrophobic material (d2) is contained in the absorbent resin particles. The structure will be described.
As the material (D), a hydrophilic material (d1) or a hydrophobic material (d2) coated with or impregnated with a hydrophobic substance (C) can be used.
Examples of the hydrophilic material (d1) include a hydrophilic organic polymer (d11) and a hydrophilic inorganic substance (d12).
Examples of the hydrophilic organic polymer (d11) include polymer electrolytes {cross-linked polymer (A), etc.], cellulose (pulp, cotton, sawdust, straw, etc.), wool, microfibrils, and bacterial cellulose.
Examples of the hydrophilic inorganic substance (d12) include glass, silica gel, silica, and clay.

The hydrophobic material (d2) includes a hydrophobic organic polymer (d21) and a hydrophobic inorganic substance (d22).
As the hydrophobic organic polymer (d21), a synthetic resin having a weight average molecular weight of 1,000 to 1,000,000 can be used. Resins, polyester resins, polyamide resins, epoxy resins, urethane resins, and the like are used.
Examples of the polystyrene resin include polystyrene, styrene-ethylene copolymer, styrene-butadiene copolymer and the like.
Examples of the polyethylene resin include high-density polyethylene and low-density polyethylene.
Examples of the polypropylene resin include polypropylene and ethylene-propylene copolymer.
Examples of the acrylic resin include polymers such as methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic ester of a long-chain alkyl alcohol having 8 to 22 carbon atoms.
Examples of the polyester resin include polyethylene terephthalate and polybutadiene terephthalate.
Nylon etc. are mentioned as a polyamide resin.
Examples of the epoxy resin include a cured product of a normal epoxy resin.
Examples of the urethane resin include a cured product of a normal polyol isocyanate.
Examples of the hydrophobic inorganic substance (d22) include carbon fiber, kaolin, talc, mica, bentonite, sericite, asbestos and shirasu.
Of these, the hydrophilic material (d1) is preferable, the hydrophilic organic polymer (d11) is more preferable, and cellulose and polymer electrolyte are particularly preferable.

  The shape of the hydrophilic material (d1) and the hydrophobic material (d2) may be any of an irregular shape (crushed shape), a true spherical shape, a film shape, a rod shape, a fiber shape, etc., but the irregular shape (crushed shape) or film The shape is preferable, and the shape is more preferably indefinite (crushed).

The volume average particle size (μm) of the hydrophilic material (d1) and the hydrophobic material (d2) is preferably from 1 to 1000, more preferably from 5 to 500, particularly preferably from 10 to 250, more particularly preferably from 15 to 150. Most preferably, it is 20-100. Within this range, the moisture resistance of the absorbent article is further improved.
In addition, a volume average particle diameter is measured by the light-scattering method (solvent: methanol) based on JISZ8825-1: 2001.

When the material (D) is a material in which the hydrophobic material (C2) is coated or impregnated with the hydrophobic material (d2), the hydrophobic substance (C) to be coated or impregnated may be the resistance to leakage of the absorbent article. In view of the above, among the hydrophobic substances (C1) containing hydrocarbon groups, polyolefin resins, waxes and long-chain fatty acid esters are preferable, more preferably waxes and long-chain fatty acid esters, particularly preferably waxes, most preferably Paraffin wax. Similarly, among the hydrophobic substances (C2) containing a hydrocarbon group having a fluorine atom, perfluoroalkanes and perfluoroalkyl ethers are preferable, perfluoroalkyl ethers are more preferable, and dipentafluoropropyl is particularly preferable. Ether, diheptafluoropropyl ether, diheptafluorobutyl ether and dinonafluorohexyl ether, most preferably diheptafluoropropyl ether and diheptafluorobutyl ether. Similarly, among the hydrophobic substance (C3) having a polysiloxane structure, polydimethylsiloxane and alkoxy-modified polysiloxane are preferable, and polydimethylsiloxane is more preferable.
Of these hydrophobic substances, the hydrophobic substance (C3) having a polysiloxane structure is preferable.

When the material (D) is a material in which the hydrophilic material (d1) is coated or impregnated with the hydrophobic material (C), the hydrophobic substance (C) to be coated or impregnated may be the resistance to leakage of the absorbent article. From the viewpoints of the above, among the hydrophobic substances (C1) containing a hydrocarbon group, polyolefin resin derivatives, wax derivatives and long-chain fatty acid sells are preferable, more preferably wax derivatives and long-chain fatty acid ssells, particularly preferably long-chains. Fatty acid esters, most preferably pentaerythritol oleic acid monoester and sorbit oleic acid monoester. Similarly, among the hydrophobic substance (C2) containing a hydrocarbon group having a fluorine atom, perfluoroalkyl carboxylic acid and perfluoroalkyl alcohol are preferable, and more preferably perfluoroalkyl carboxylic acid metal salt and perfluoroalkyl. Alkyl alcohol, particularly preferably a perfluoroalkylcarboxylic acid metal salt. Similarly, among the hydrophobic substance (C3) having a polysiloxane structure, polyether-modified polysiloxane, carboxyl-modified polysiloxane, epoxy-modified polysiloxane, and amino-modified polysiloxane are preferable, and carboxyl-modified polysiloxane is more preferable. Epoxy-modified polysiloxanes and amino-modified polysiloxanes, particularly preferably carboxyl-modified polysiloxanes and amino-modified polysiloxanes, most preferably amino-modified polysiloxanes.
Of these hydrophobic substances, the hydrophobic substance (C3) having a polysiloxane structure is preferable.

  The content (% by weight) of the hydrophobic substance (C) in the material (D) is preferably 0.001 to 3, more preferably 0.005 to 1, particularly preferably based on the weight of (D). It is 0.07 to 0.5, most preferably 0.1 to 0.3. Within this range, the moisture resistance of the absorbent article is further improved.

  The content (% by weight) of the material (D) is preferably from 0.1 to 50, more preferably from 0.5 to 20, particularly preferably from 1 to 10, based on the weight of the crosslinked polymer (A). Preferably it is 2-4. Within this range, the moisture resistance of the absorbent article is further improved.

  When the absorbent resin particles have a structure containing the material (D), the absorbent resin particles are (1) a method of mixing and kneading the material (D) and the crosslinked polymer (A), or (2) It can be produced by a method of polymerizing the crosslinked polymer (A) in the presence of the material (D).

(1) The mixing method of the crosslinked polymer (A) and the material (D) is such that the material (D) exists inside the crosslinked polymer (A) {preferably the crosslinked polymer (A) and the material. If (D) is mixed so that it has a sandwich structure, there is no limitation.
However, the material (D) is not a dried product of the crosslinked polymer (A), but is preferably mixed with the hydrogel (A) or the polymerization liquid (A), more preferably the hydrogel of (A). Is to be mixed with. In addition, it is preferable to mix uniformly so that mixing may be carried out.
Although there is no restriction | limiting in particular as timing which mixes material (D) and (A), It is the same as the case where a connection part (RC) is mixed.
As the mixing / kneading apparatus, the same apparatus as used for mixing the connecting portion (RC) can be used.

  (2) In the method of polymerizing the crosslinked polymer (A) in the presence of the material (D), the material (D) can be emulsified or dispersed in the polymerization solution of the crosslinked polymer (A) and polymerized. .

When the hydrophobic material (C) is coated or impregnated on part or all of the surface of the hydrophilic material (d1) or the hydrophobic material (d2), the hydrophobic material (C) is dissolved or emulsified / dispersed in a solvent. Alternatively, it can be used as a liquid by heating to a melting point of (C) or higher and melting.
In order to coat or impregnate the hydrophobic substance (C) on the hydrophilic material (d1) or the hydrophobic material (d2), the liquid is sprayed on (d1) or (d2), or (d1) or This can be achieved by dipping (d2). In addition, after contacting the emulsified dispersion of the solid hydrophobic substance (C) or (C) with the hydrophilic material (d1) or the hydrophobic material (d2), the coating is heated to the melting point of (C) or higher. Or it can also be impregnated.
When a solvent is used for coating or impregnation, the solvent is preferably distilled off. In this case, the content (% by weight) of the organic solvent after distillation is preferably 10 to 0.01, more preferably 5 to 0.05, particularly preferably based on the weight of the material (D). 3 to 0.1, most preferably 1 to 0.5. Within this range, the moisture resistance (particularly the amount of water retained) of the absorbent article is further improved. When water is contained in the solvent, the water content (% by weight) after distillation is preferably 0 to 20, more preferably 0 to 10, particularly preferably 0 to 5, based on the weight of the material (D). Most preferably, it is 0-2. Within this range, the moisture resistance (particularly the amount of water retained) of the absorbent article is further improved.
The method for distilling off and the method for measuring the solvent content are the same as in the case of the crosslinked polymer (A).
The solvent that can be used is not particularly limited as long as it dissolves (C), but the above-mentioned water and / or volatile solvent are preferable.
As a mixing apparatus applicable to spraying, dipping, or contact, a nauter mixer, a turbulizer, and the like can be given.

In the case of hydrogel particles containing water in the absorbent resin particles, the hydrogel can be crushed as necessary. The size (longest diameter) of the hydrogel particles after 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 crushing method can employ the same method as that for the crosslinked polymer (A).

When a solvent (including a volatile solvent) is used for production of the absorbent resin particles, the solvent can be distilled off after the polymerization.
When the solvent contains an organic solvent, the content (% by weight) of the organic solvent after distillation is preferably 10 to 0.01, more preferably 5 to 0.05, based on the weight of the absorbent resin particles. Particularly preferred is 3 to 0.1, and most preferred is 1 to 0.5. Within this range, the absorption performance (particularly the water retention amount) of the absorbent resin particles is further improved.

Further, when water is contained in the solvent, the water content (% by weight) after the distillation is preferably 0 to 20, more preferably 0 to 10, particularly preferably 0 to 5, based on the weight of the absorbent resin particles. Most preferably, it is 0-2. Within this range, the absorption performance (particularly the water retention amount) and the handling properties after drying (powder fluidity of the absorbent resin particles, etc.) are further improved.
In addition, the content of the organic solvent and the method for measuring the water content and the method for distilling off the solvent are the same as in the case of the crosslinked polymer (A).

The absorbent resin particles can be pulverized. When the absorbent resin particles contain a solvent, the solvent is preferably pulverized after being distilled off (dried).
When pulverizing, the weight average particle size (μm) after pulverization is preferably 100 to 800, more preferably 200 to 500, and particularly preferably 300 to 400. Within this range, handling properties after pulverization (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 (A).

The smaller the content of fine particles, the better the absorption performance, and the content of fine particles of 106 μm or less in the total particles is preferably 3% by weight or less, more preferably the content of fine particles of 150 μm or less in the total particles is 3% by weight. It is as follows. The content of the fine particles can be obtained by using a plot created when obtaining the above weight average particle diameter.
For pulverization and particle size adjustment, the same method as in the case of the crosslinked polymer (A) can be employed.
The shape of the absorbent resin particles 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, from the viewpoint of good entanglement with the fibrous material for use in paper diapers and the like and no fear of dropping off from the fibrous material, an irregular crushed shape is preferable.

  The absorbent resin particles can be subjected to surface crosslinking as necessary. As the crosslinking agent (surface crosslinking agent) for performing the surface crosslinking, the same as the internal crosslinking agent (b) can be used. As the surface cross-linking agent, from the viewpoint of the absorption performance of the absorbent resin particles, the water-soluble substituent of the water-soluble vinyl monomer (a1) and / or the water-soluble substituent generated by hydrolysis of the vinyl monomer (a2) is reacted. The cross-linking agent (b3) having at least two functional groups that can be used is preferable, more preferably polyvalent glycidyl, particularly preferably ethylene glycol diglycidyl ether and glycerin diglycidyl ether, and most preferably ethylene glycol diglycidyl ether.

  In the case of surface cross-linking, the content (% by weight) of the surface cross-linking agent is the total weight of the vinyl monomers (a1) and / or (a2), the internal cross-linking agent (b) and other vinyl monomers (a3) used as necessary. Is preferably 0.001 to 7, more preferably 0.002 to 5, particularly preferably 0.003 to 4. That is, in this case, the upper limit of the content (% by weight) of the surface cross-linking agent is preferably 7 based on the total weight of (a1) and / or (a2), (b) and (a3), more preferably 5, particularly preferably 4. Similarly, the lower limit is preferably 0.001, more preferably 0.002, and particularly preferably 0.003. In this range, the absorption performance is further improved. Surface cross-linking can be achieved by a method of spraying or impregnating absorbent particles with an aqueous solution containing a surface cross-linking agent, followed by heat treatment (100 to 200 ° C.).

The absorbent resin particles of the present invention preferably further contain a diffusion penetrant (E) as a constituent component. When the diffusion penetrant (E) is included, the absorption performance (absorption amount and absorption rate) 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, “the latest technology of water-soluble polymer” CMC Published in May 2000; or “surfactant application technology” described in CMC publication December 2002 issue). When the crosslinked polymer (A) is obtained by aqueous solution polymerization, among the surfactants, anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants can be used, One or more of these may be used in combination.

  Examples of the anionic surfactant include ether carboxylic acids having 12 to 300 carbon atoms or salts thereof, [polyoxyethylene (polymerization degree = 1 to 5) sodium lauryl ether acetate and polyoxyethylene (polymerization degree = 1 to 5) lauryl. Sulfosuccinic acid disodium etc.], C12-C300 alkyl (ether) sulfate ester salt [sodium lauryl sulfate, polyoxyethylene (degree of polymerization = 1-5) sodium lauryl sulfate, polyoxyethylene (degree of polymerization = 1-5) ) Triethanolamine lauryl sulfate and polyoxyethylene (degree of polymerization = 1-5) coconut oil fatty acid monoethanolamide sodium sulfate], alkyl (or alkylphenyl) sulfonate having 12 to 24 carbon atoms [sodium dodecylbenzenesulfonate, Diethylhexyl sulfosuccinate sodium Etc.], alkyl (ether) phosphate ester salts having 12 to 300 carbon atoms [sodium lauryl phosphate and polyoxyethylene (degree of polymerization = 1-100) sodium lauryl ether phosphate, etc.], fatty acid salts having 12 to 24 carbon atoms [Sodium laurate and triethanolamine laurate, etc.], acylated amino acid salt [coconut oil fatty acid methyl taurine sodium, coconut oil fatty acid sarcosine sodium, coconut oil fatty acid sarcosine triethanolamine, N-coconut oil fatty acid acyl-L-glutamic acid tri Ethanolamine, N-coconut oil fatty acid acyl-L-glutamic acid sodium and lauroylmethyl-β-alanine sodium etc.] and others [sulfoxysuccinic acid polyoxyethylene (degree of polymerization = 1-5) lauroylethanolamide disodium etc.] It is done.

  Nonionic surfactants include aliphatic alcohol (12 to 24 carbon atoms) alkylene oxide (2 to 5 carbon atoms) adduct (degree of polymerization = 1 to 5) [addition of lauryl alcohol ethylene oxide (degree of polymerization = 3). ) Product, oleyl alcohol ethylene oxide addition (polymerization degree = 3) product and McCoal alcohol ethylene oxide addition (polymerization degree = 3) product], polyoxyalkylene (2-8 carbon atoms, polymerization degree = 1-5) higher fatty acid (C12-24) ester [polyethylene glycol monostearate (polymerization degree = 3), polyethyleneglycol distearate (polymerization degree = 3), etc.], polyvalent (2-10 valent) alcohol fatty acid (carbon number 8-24) ) Esters [glyceryl monostearate, ethylene glycol monostearate, sorbitan lauric acid ( No / di) ester, sorbitan palmitic acid (mono / di) ester, sorbitan stearic acid (mono / di) ester, sorbitan oleic acid (mono / di) ester, sorbitan coconut oil (mono / di) ester, etc.], polyoxy Alkylene (carbon number 2-8, polymerization degree = 1-5) polyhydric (2-10 valent) alcohol higher fatty acid (carbon number 8-24) ester [polyoxyethylene (degree of polymerization = 2) sorbitan lauric acid (mono / Di) ester, polyoxyethylene (degree of polymerization = 2) sorbitan palmitic acid (mono / di) ester, polyoxyethylene (degree of polymerization = 3) sorbitan stearic acid (mono / di) ester, polyoxyethylene (degree of polymerization = 3) ) Sorbitan oleic acid (mono / di) ester, polyoxyethylene (degree of polymerization = 2) lauric acid (mono / di) Steal, polyoxyethylene (degree of polymerization = 3) stearic acid (mono / di) ester, polyoxyethylene (degree of polymerization = 3) oleic acid (mono / di) ester, dioleic acid methyl glucoside, etc.], fatty acid alkanolamide [1 : 1 type coconut oil fatty acid diethanolamide, 1: 1 type lauric acid diethanolamide, etc.], polyoxyalkylene (2 to 8 carbon atoms, degree of polymerization = 1 to 5) alkyl (1 to 22 carbon atoms) phenyl ether (polyoxy Ethylene (degree of polymerization = 2) nonylphenyl ether, etc., polyoxyalkylene (carbon number 2-8, degree of polymerization = 1-5) alkyl (carbon number 8-24) amino ether, alkyl (carbon number 8-24) dialkyl (C1-C6) amine oxide [lauryl dimethylamine oxide etc.] etc. are mentioned. In the above, (mono / di) ester means monoester or diester. The same applies to the following.

  Further, as the cationic surfactant, quaternary ammonium salts [stearyl trimethyl ammonium chloride, behenyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, ethyl lanolin sulfate fatty acid aminopropylethyl dimethyl ammonium, etc.] and amine salts [diethylamino stearate] Ethylamide lactate, dilaurylamine hydrochloride, oleylamine lactate, etc.].

  In addition, as the amphoteric surfactant, betaine-type amphoteric surfactant [coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, Lauryl hydroxysulfobetaine and lauroylamidoethylhydroxyethylcarboxymethylbetaine hydroxypropyl sodium phosphate etc.] and amino acid type amphoteric surfactants [sodium β-laurylaminopropionate etc.] and the like.

  Of these diffusion penetrants (E), anionic surfactants and nonionic surfactants are preferable from the viewpoint of the anti-moisture properties of the absorbent article, and more preferably alkyl (ether) sulfate ester salts, alkyl ( Or alkylphenyl) sulfonate, alkyl (ether) phosphate ester salt, fatty acid salt and polyhydric alcohol fatty acid ester, particularly preferably sodium lauryl sulfate, sodium lauryl phosphate, sodium dodecylbenzenesulfonate, sodium diethylhexylsulfosuccinate Sodium lauryl phosphate, sodium laurate, 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 Rubitan'yashi oil (mono / di) ester, sorbitan laurate (mono / di) esters, most preferably sodium dodecyl benzene sulfonate, hexyl sodium sulfosuccinate to diethyl.

  When the crosslinked polymer (A) is obtained by emulsion polymerization or reverse phase suspension polymerization, the diffusion penetrant (E) is a surfactant (emulsification) used during emulsion polymerization or reverse phase suspension polymerization. -The same surfactant as (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 hardly 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 the diffusion penetrant (E), one having a higher difference in HLB value from the hydrophobic substance (C) is preferable. The difference in HLB between (C) and (E) is preferably 1 to 10, more preferably 2 to 8, particularly preferably 3 to 7. Within this range, the moisture resistance of the absorbent article is further improved.
The HLB value of the diffusion penetrant (E) is preferably 5 to 12, more preferably 6 to 11, particularly preferably 7 to 10, and most preferably 8 to 9. Within this range, the moisture resistance of the absorbent article is further improved.

  When the diffusion penetrant (E) is contained, the content (% by weight) of (E) is preferably 0.001 to 3, more preferably 0.005, based on the weight of the crosslinked polymer (A). 1, particularly preferably 0.07 to 0.5, most preferably 0.1 to 0.3. Within this range, the moisture resistance of the absorbent article is further improved.

When the diffusion penetrant (E) is contained, it is preferably present inside the crosslinked polymer (A), more preferably present on the surface of the connecting portion (RC) or the material (D).
In the case of the aqueous solution polymerization method, the timing of adding the diffusion penetrant (E) is not particularly limited, but examples include during the polymerization step, immediately after the polymerization step, during crushing (minching) of the hydrogel and during drying of the hydrogel. Among these, from the viewpoint of the anti-moisture resistance of the absorbent article, it is preferably immediately after the polymerization step and during the crushing (mincing) step of the hydrogel, and more preferably immediately after the polymerization step.
In the case of reverse phase suspension polymerization or emulsion polymerization, the diffusion penetrant (E) is added immediately after the polymerization step, during the dehydration step (during the step of dehydrating to about 10% by weight of water), immediately after the dehydration step, and polymerization. And the like, during the step of separating and distilling off the organic solvent used in the above, and during the drying of the hydrogel. Among these, from the viewpoint of the resistance to absorption of the absorbent article and the stability during polymerization, immediately after the polymerization process, during the dehydration process, immediately after the dehydration process and during the process of separating and distilling the organic solvent used for the polymerization are preferable. More preferably, it is immediately after the polymerization step, during the dehydration step, immediately after the dehydration step, and during the step of separating and distilling the organic solvent used for the polymerization.
As a method for containing the diffusion penetrant (E) and a device used therefor, a method of mixing the connecting portion (RC) or the material (D) and the crosslinked polymer (A), a device used therefor, and the like are used. it can.
In order for the diffusion penetrant (E) to be present on the surface of the connecting part (RC) or the material (D), after containing (E), the connecting part (RC) {or hydrophobic substance (C)} or A method of mixing the material (D) can be applied.

  The diffusion penetrant (E) can be used in a form dissolved and / or emulsified in water and / or a volatile solvent. The volatile solvent is the same as in the case of the hydrophobic substance (C), and the preferred range and use amount are also the same.

The absorption amount (ml) under diffusion of the absorbent resin particles of the present invention is preferably 40 to 70, more preferably 45 to 65, and particularly preferably 50 to 60. Within this range, when the absorbent resin particles of the present invention are applied to an absorbent article, more excellent resistance to leakage is exhibited.
The absorption amount (ml) of the absorbent resin particles under diffusion is a value determined by the following measurement method.
Measurement method: 1.25 g of the measurement sample (3) is placed in a wire cylinder (2) in a filtration cylindrical container (2) having a wire mesh (1) (aperture 150 μm) at the bottom of a vertically standing cylinder (inner diameter 60 mm, length 50 mm). 1) Throw up to a uniform thickness on top, with a feed pipe (4) (inner diameter 4 mm, length 50 mm) placed perpendicular to the top surface of the disk and with an inner hole penetrating the bottom surface of the disk Place the disk (5) (59 mm in diameter, 4 mm in thickness, 29 g in weight) on the measurement sample (3) so that the bottom surface of the disk (5) and the measurement sample (3) are in contact with each other. After putting a ring-shaped weight (6) (outer diameter 50 mm, inner hole diameter 16 mm, weight 150 g) on the upper surface, physiological saline (25 ° C.) was continuously poured from the input pipe (4) at a rate of 10 ml / min. Necessary from the start of pouring until the saline begins to leak from the wire mesh (1) Measuring the time (T), calculates the diffusion under absorption from the formula (1). However, if the poured physiological saline reaches the line 5 mm below the top of the charging pipe (4) before leaking from the wire mesh (1), the measurement is stopped at this point and it is recorded that measurement is impossible. .

The measurement of the absorption amount under diffusion will be described in detail as follows. 1 and 2 are a front view and a perspective transparent view, respectively, schematically showing the device used for measuring the absorption amount under diffusion.
The apparatus used for measuring the amount of absorption under diffusion consists of a filtering cylindrical container (2), a disk with a feeding tube (5), and a ring weight (6) (see FIGS. 1 and 2). Furthermore, a syringe, a beaker, a metering pump or the like for pouring physiological saline at a constant speed is necessary, and a metering pump is preferable from the viewpoint of accuracy.
The cylinder constituting the filtration cylindrical container (2) is not limited in material as long as the inner diameter is 60 mm and the length is 50 mm, but is transparent from the viewpoint of internal observation (polyvinyl chloride, polycarbonate, polypropylene, polyethylene, etc.) Is preferred. The bottom of the cylinder is closed with a wire mesh (1) having an opening of 150 μm, and has a structure in which physiological saline can pass but measurement sample (3) cannot pass. The wire mesh conforms to JIS Z8801-1: 2000.
The disk constituting the disk (5) with the input pipe (4) has a diameter of 59 mm, a thickness of 4 mm, and a weight of 29 g (including the weight of the input pipe (4)), and is a transparent material from the viewpoint of internal observation. Is preferred. At the center of the disk, an input tube (4) having an inner diameter of 4 mm and a length of 50 mm is arranged perpendicular to the upper surface of the disk, and the inner hole of the input tube (4) penetrates to the bottom surface of the disk. Thus, the physiological saline poured into the input tube (4) is poured into the measurement sample below the disk (5). The disk (5) with the input tube can hold the measurement sample (3) between the bottom surface of the disk and the top surface of the wire mesh (1) by being inserted into the filtering cylindrical container (2).
The ring-shaped weight (6) has an outer diameter of 50 mm, an inner hole diameter of 16 mm, and a weight of 150 g, and the input tube (4) of the disk with input tube (5) penetrates the ring-shaped (donut-shaped) inner hole. A load is applied to the upper surface of the disk. The material of the ring-shaped weight (6) is preferably made of metal (such as steel, copper, stainless steel and lead) from the viewpoint of space.
As the syringe and beaker, a normal instrument used in a chemical experiment can be used, and as the metering pump, a gear pump, a tube pump, a syringe pump, or the like can be used.

  In the measurement, first, the cylindrical filtering container (2) is fixed so that the tube axis direction is vertical (the direction of gravity), and then 1.25 g of the measurement sample (3) is evenly distributed (distributed) on the wire mesh (1). And a disc (5) with a feeding tube is placed on the measurement sample (3) so that the bottom of the disc is in contact with the measurement sample (3). Further, a ring weight (6) is placed on the upper surface of the disk (5).

  Next, physiological saline is continuously poured into the charging tube (4) at a rate of 10 ml / min. At this time, the physiological saline poured into the charging pipe (4) is not subjected to pressure other than atmospheric pressure and the column pressure of physiological saline. When a metering pump or a syringe is used, the outer diameter of the injection nozzle to the charging pipe (4) is preferably about 3 mm or less so that the discharge pressure of the metering pump is not applied.

Then, the time (T) from the start of pouring physiological saline to the start of leakage from the wire mesh (1) is measured, and the absorbed amount under diffusion is calculated from the equation (1). If physiological saline reaches the 5 mm line from the upper end of the input pipe (4) before it stays in the input pipe (4) and leaks from the wire mesh (1), the measurement is stopped at this point. Record that absorption under diffusion is not measurable.
The physiological saline used and the temperature of the measurement atmosphere are 25 ± 2 ° C.

The absorbent resin particles of the present invention preferably have an absorption time (Z) (unit: minute) of 0.5 to 3.5, more preferably 0.6 to 3, and then preferably 0.7 to 3.5. 2.5, particularly preferably 0.8 to 2, and most preferably 0.9 to 1.8.
The absorbent resin particles of the present invention preferably satisfy the formulas (2) and (3).

（ｈ２）は、測定試料の無い場合について上記と同様の操作により計測したティーバックの重量である。 The water retention amount (X) is the water retention amount (g / g) of the absorbent resin particles after being immersed in physiological saline for 1 hour, and is measured by the following method.
<Measurement method of water retention amount (X)>
Place 1.00 g of a measurement sample in a tea bag (20 cm long, 10 cm wide) made of a 250 mesh nylon net and immerse it in 1,000 cc of physiological saline (salt concentration 0.9 wt%) for 1 hour without stirring. After that, hang for 15 minutes and drain. Then, the tea bag is placed in a centrifuge, centrifuged at 150G for 90 seconds to remove excess physiological saline, and the weight (h1) including the tea bag is measured to obtain the water retention amount (X) from the following equation. . The temperature of the physiological saline used and the measurement atmosphere is 25 ° C. ± 2 ° C.

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

The water retention amount (X) preferably satisfies the formula (8) instead of the formula (2), more preferably satisfies the formula (9), particularly preferably satisfies the formula (10), most preferably the formula (11) is satisfied. When these formulas are satisfied, it becomes easier to manufacture an absorbent article that exhibits higher absorption performance in any state and is less likely to cause leakage.

  The liquid flow rate (Y) is a flow rate (ml / min) of physiological saline under a load of 21.4 Pa after 1 hour of immersing the absorbent resin particles in physiological saline, and is measured by the following method. The

<Measurement method of liquid flow rate (Y)>
A hydrogel particle is prepared by immersing 0.32 g of a measurement sample in 50 ml of physiological saline for 1 hour.
On the other hand, a cock (inner diameter: 5 mm, length: 10 cm) of a closed chromatograph tube (diameter (inner diameter): 25.4 mm, length: 35 cm) with a cock and a capacity scale (opening: 10 to 15 μm) ), And the chromatograph tube is fixed vertically (in the direction of gravity) with this cock on the bottom.
Next, the above hydrogel particles are transferred to a chromatograph tube together with physiological saline, and a pressure shaft (weight: 15) with a circular wire mesh (diameter 25 mm) having an opening of 150 μm (JIS Z8801-1: 2000) at one end is vertically attached. 0.5 g, length: 31.5 cm) is placed so that the wire mesh is on the water-containing gel particle side, and a weight (91.5 g) is further placed thereon and allowed to stand for 1 minute.
Open the cock at the bottom of the chromatograph tube, measure the time (T1; seconds) required for the liquid level in the tube to change from 60 ml to 40 ml, and obtain the liquid flow rate (Y, ml / min) from the following equation. The physiological saline used and the temperature of the measurement atmosphere are 25 ° C. ± 2 ° C.

（Ｔ２）は、測定試料の無い場合について上記と同様の操作により計測した時間である。すなわち、コック及び容量目盛が付いたフィルター閉じ込み型クロマトグラフ管に生理食塩水５０ｍｌを入れ、管内の液量が６０ｍｌから４０ｍｌになるのに要する時間（Ｔ２；秒）である。

(T2) is the time measured by the same operation as described above when no measurement sample is present. That is, it is the time (T2; seconds) required for 50 ml of physiological saline to be put into a closed filter chromatograph tube with a faucet and volumetric scale, and the amount of liquid in the tube be changed from 60 ml to 40 ml.

The absorption time (Z) is the absorption time (min) until it reaches 70% by volume of the saturation swelling degree in physiological saline, and is measured by the following method.
<Measurement method of absorption time (Z)>
After putting 1.0 g of a measurement sample into a 100 ml graduated cylinder, 100 ml of physiological saline is added all at once, and the volume occupied by the swelled measurement sample is read every minute (the graduated cylinder corresponding to the uppermost end of the swelled measurement sample). The measurement is performed for 5 minutes until the change in the measured value becomes ± 0 (the measurement sample absorbs physiological saline and gradually swells to increase its volume, A saturated swelling state is reached after a certain time.) Then, a volume-time graph in which time is plotted on the horizontal axis and volume of the measurement sample swollen on the vertical axis is created, and the volume (saturated swelling degree) when the change in measured value for 5 minutes becomes ± 0 is 100 volumes. %, A time corresponding to 70% by volume with respect to the saturation swelling degree is defined as an absorption time (Z).
The physiological saline used and the temperature of the measurement atmosphere are 25 ° C. ± 2 ° C.

  It is preferable to satisfy Formula (12) instead of Formula (3), more preferably to satisfy Formula (13), particularly preferably to satisfy Formula (14), and most preferably to satisfy Formula (15). It is. When these formulas are satisfied, it becomes easier to produce an absorbent article that exhibits higher absorption performance in any state and is less likely to cause leakage.

  Furthermore, in Formula (3), it is preferable to satisfy Formula (16), more preferably to satisfy Formula (17), particularly preferably to satisfy Formula (18), and most preferably to satisfy Formula (19). It is. When these formulas are satisfied, it becomes easier to produce an absorbent article that exhibits higher absorption performance in any state and is less likely to cause leakage.

The water content (% by weight) of the absorbent resin particles of the present invention is preferably from 1 to 12, more preferably from 2 to 10, particularly from the viewpoint of workability, texture, moisture resistance, etc. when applied to absorbent articles. Preferably it is 4-8. 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 the surface cross-linking process and the hydration process. Further, the moisture content can be measured by the weight reduction rate after drying treatment (120 ± 5 ° C., 30 minutes, etc.) in the same manner as the method for measuring moisture.

In the absorbent resin particles of the present invention, if necessary, at any stage {polymerization step of cross-linked polymer (A), crushing step, drying step, pulverization step, surface cross-linking step and / or before and after these steps, etc.} Additives can be added.
As additives, antiseptics, fungicides, antibacterial agents, antioxidants, ultraviolet absorbers, colorants, fragrances, deodorants and organic fibrous materials can be used, and one or more of these can be used. May be used in combination.

Examples of the preservative include preservatives such as salicylic acid, sorbic acid, dehydroacetic acid and methylnaphthoquinone, and bactericides such as chloramine B and nitrofurazone.
Examples of fungicides include butyl p-oxybenzoate.
Examples of the antibacterial agent include benzalkonium chloride salt and chlorhexidine gluconate.

  Antioxidants include triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenylpropionate) and 3,5-di-t-butyl-4-hydroxybenzyl Examples include hindered phenol antioxidants such as phosphonate-diethyl ester and amine antioxidants such as n-butylamine, triethylamine and diethylaminomethyl methacrylate.

  Examples of the ultraviolet absorber include 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3,5-di Benzotriazole ultraviolet absorbers such as -t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole and 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole; 2- (4 , 6-Diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol and other triazine-based UV absorbers; 2-hydroxy-4-n-octyloxybenzophenone and other benzophenones And oxalic acid anilide ultraviolet absorbers such as 2-ethoxy-2′-ethyloxalic acid bisanilide, etc. That.

Examples of the colorant include inorganic pigments such as titanium oxide and ferrite, organic pigments such as azo lake, benzimidazolone and phthalocyanine, and dyes such as nigrosine and aniline.
As a fragrance | flavor, natural fragrance | flavors, such as a fragrance | flavor, abies oil, and turpentine oil, and synthetic fragrance | flavors, such as menthol, citral, p-methylacetophenone, and floral, etc. are mentioned.
Examples of the deodorant include zeolite, silica, flavonoid, cyclodextrin and the like.

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

By applying the absorbent resin particles of the present invention to various absorbers, absorbent articles having excellent absorption performance can be produced.
As a method of applying the absorbent resin particles to the absorbent body, (1) a method in which the absorbent resin particles are dispersed between layers of fibrous materials composed of pulp or the like arranged in a layer; (2) pulp, heat A method of mixing a fibrous material composed of fusible fibers and the like and absorbent resin particles; (3) a method of sandwiching absorbent resin particles together with fibrous materials, if necessary, using two or more water-absorbing papers and nonwoven fabrics; Etc.

  As the fibrous material, fibrous materials conventionally used for absorbent articles such as various fluff pulps and cotton-like pulps can be used. There are no particular restrictions on the raw materials (conifers, hardwoods, etc.), production methods [craft pulp, chemical pulp, semi-chemical pulp, chemithermomechanical pulp (CTMP), etc.], bleaching methods and the like. As the fibrous material, in addition to the organic fibrous material described above, a synthetic fiber that does not swell in water can be used alone or in combination with the above fluff pulp or cotton pulp, if necessary. Examples of synthetic fibers include polyolefin fibers (polyethylene fibers and polypropylene fibers, etc.), polyester fibers (polyethylene terephthalate fibers, etc.), polyolefin / polyester composite fibers, polyamide fibers, and polyacrylonitrile fibers.

The length and thickness of the fibrous material are not particularly limited. Usually, the length is 1 to 200 mm, and the thickness is preferably 0.1 to 100 denier (0.11 to 110 dtex).
The shape is not particularly limited as long as it is fibrous, and examples thereof include a web shape, a thin cylindrical shape, a cut split yarn shape, a staple shape, and a filament shape.

  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 to 95 is preferable, more preferably 40 to 94, and particularly preferably 50 to 93, based on the total weight of 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 has a light touch even when it absorbs liquids to be absorbed (body fluids 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.
Therefore, by using the absorbent resin particles of the present invention, it is possible to easily manufacture an absorbent article that exhibits high absorption performance in any state.
That is, even when a load is applied such as when the user is sitting or lying down, the amount of absorption and the absorption speed do not decrease, and as a result, problems such as leakage are very unlikely to occur.

The absorbent article is preferably an absorbent article including an absorbent body, a liquid permeable sheet, and a breathable back sheet, and more preferably an absorbent article as a sanitary article.
Sanitary goods include paper diapers (children's diapers and adult paper diapers, etc.), napkins (sanitary napkins, etc.), paper towels, pads (incontinence pads, surgical underpads, etc.) and pet sheets (pet urine absorbing sheets). Etc. Of these hygiene articles, they are more suitable for disposable diapers. Furthermore, 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 (the paper diaper was heated and dried 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 5 minutes after the start of measurement is defined as the surface dryness value by SDME.

  The absorbent resin particles of the present invention are used not only for hygiene products as described above, but also for pet urine absorbent, urine gelling agent for portable toilets, freshness retaining agents such as fruits and vegetables, drip absorbents for meat and seafood, cold insulation It is also useful for various applications such as agents, disposable warmers, gelling agents for batteries, water retention agents for 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.

<Synthesis of hydrous gel polymer (AA-1)>
In a glass reaction vessel, 77 parts of sodium acrylate, 22.85 parts of acrylic acid, 0.15 part of N, N′-methylenebisacrylamide and 293 parts of deionized water, 0.001 part of dichlorotris (triphenylphosphine) ruthenium The contents were 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 By adding and mixing 0.8 part of a 2% aqueous solution of amidinopropane dihydrochloride to initiate polymerization, the reaction solution reached 80 ° C, and then polymerized at a polymerization temperature of 80 ± 2 ° C for about 5 hours to crosslink. A hydrogel polymer (AA-1) comprising the polymer (A1) was obtained. The water content (120 ± 5 ° C. × 30 minutes) was 74.6%.

<Preparation of material (DD11)>
A solution prepared by dissolving 0.0005 part of amino-modified silicone (Shin-Etsu Chemical Co., Ltd. product: KF354) in 10 parts of methanol is added to 5 parts of clay (ROCKWOOD ADDIIVES LIMITEDED: LAPONIPE XLG), and a biomixer (Japan) is added at 25 ° C. After stirring for 2 minutes with ABM-2 (manufactured by Seiki Co., Ltd.), it was dried at 60 ° C. for 1 hour to obtain a hydrophobically treated material (DD11).

<Preparation of material (DD12)>
Add 5 parts of pulp (Nippon Paper Chemical Co., Ltd. product: KC Flock W-400G) and 0.0005 part of dimethyl silicone (manufactured by Dow Corning Toray, trade name: SH200) in 10 parts of methanol. The mixture was 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 a hydrophobically treated material (DD12).

<Preparation of material (DD13)>
A solution prepared by dissolving 0.0005 part of dimethyl silicone (trade name: SH200, manufactured by Toray Dow Corning Silicone Co., Ltd.) in 10 parts of methanol is added to 5 parts of silica (Nippon Aerogel Co., Ltd. product: Aerogel 200PE). The mixture was stirred for 2 minutes with a mixer (ABM-2 type, manufactured by Nippon Seiki Co., Ltd.) and then dried at 60 ° C. for 1 hour to obtain a hydrophobic treatment material (DD13).

<Preparation of material (DD14)>
A liquid prepared by dissolving 0.0005 part of liquid paraffin (viscosity: 50 mPa · s) in 10 parts of cyclohexane was added to 5 parts of clay (manufactured by ROCKWOODS ADDIIVES LIMITTED): Biomixer (Nippon Seiki Co., Ltd.) Manufactured by ABM-2 type) for 2 minutes and dried at 60 ° C. for 1 hour to obtain a hydrophobically treated material (DD14).

<Preparation of material (DD15)>
A solution obtained by dissolving 0.0005 parts of carbokill-modified wax (manufactured by Sanyo Chemical Industries, Ltd., trade name: Sun Wax 165-P) in 5 parts of pulp (Nippon Paper Chemical Co., Ltd. product: KC Flock W-400G) in 10 parts of cyclohexane The mixture was added and stirred at 25 ° C. for 2 minutes with a biomixer (ABM-2 type, manufactured by Nippon Seiki Co., Ltd.) and then dried at 60 ° C. for 1 hour to obtain a hydrophobic treatment material (DD15).

<Preparation of material (DD16)>
A solution prepared by dissolving 0.0005 parts of carbokill-modified wax (manufactured by Sanyo Chemical Industries, Ltd., trade name: Sun Wax 165-P) in 10 parts of cyclohexane is added to 5 parts of silica (Nippon Aerogel product: Aerogel 200PE). After stirring for 2 minutes with a biomixer at 25 ° C., drying was performed at 60 ° C. for 1 hour to obtain a hydrophobically treated material (DD16).

<Example 1>
To 400 parts of the hydrogel polymer (AA-1), 40 parts of the material (DD11) and a diffusion penetrant (E1) (Sanyo Kasei Kogyo Co., Ltd .: Sanmorin OT70, an anionic surfactant) 0.4 part are added. After kneading for 5 minutes at 25 ° C. in a machine (hole diameter of the eye plate: 6 mm, 12VR-400K manufactured by Iizuka Kogyo Co., Ltd.), it is dried with a ventilated band dryer under conditions of 135 ° C. and a wind speed of 2.0 m / sec. A dried polymer was obtained.
This polymer dried product was pulverized with a commercially available juicer mixer and adjusted to a particle size of 250 to 600 μm using a sieve having an opening of 600 and 250 μm, and then 100 parts of this polymer was stirred at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron). 2 parts of a 10% water / methanol mixed solution of ethylene glycol diglycidyl ether (water / methanol weight ratio = 70/30) while being sprayed and mixed, and mixed at 140 ° C. for 30 minutes. The absorbent resin particle (1) was obtained by standing still and heat-crosslinking.

<Example 2>
Absorbent resin particles (2) were obtained in the same manner as in Example 1 except that the material (DD12) was used instead of the material (DD11).

<Example 3>
Absorbent resin particles (3) were obtained in the same manner as in Example 1 except that the material (DD13) was used instead of the material (DD11).

<Example 4>
Absorbent resin particles (4) were obtained in the same manner as in Example 1 except that the material (DD14) was used instead of the material (DD11).

<Example 5>
Absorbent resin particles (5) were obtained in the same manner as in Example 1 except that the material (DD15) was used instead of the material (DD11).

<Example 6>
Absorbing resin particles (6) were obtained in the same manner as in Example 1 except that the material (DD16) was used instead of the material (DD11).

<Example 7>
Example in which the diffusion penetrant (E2) (manufactured by Sanyo Kasei Kogyo Co., Ltd .: NAROACTY ID50, nonionic surfactant) was used in place of the diffusion penetrant (E1) (manufactured by Sanyo Chemical Industries Co., Ltd .: Sanmorin OT70) In the same manner as in No. 1, absorbent resin particles (7) were obtained.

<Example 8>
Instead of the material (DD11), the material (DD12) is replaced with the diffusion penetrant (E1) (manufactured by Sanyo Chemical Industries, Ltd .: Sanmorin OT70). Absorbent resin particles (8) were obtained in the same manner as in Example 1 except that was used.

<Example 9>
Absorbent resin particles (9) were obtained in the same manner as in Example 1 except that the weight of the material (DD11) was changed to 5.4 parts.

<Example 10>
40 parts of the material (DD11) used was replaced with 2.7 parts, and 0.4 parts of the diffusion penetrant (E1) (Sanyo Kasei Kogyo Co., Ltd .: Sanmorin OT70) was replaced with 0.14 parts. Except that, the absorbent resin particles (10) were obtained in the same manner as in Example 1.

<Example 11>
400 parts of water-containing gel polymer (AA-1), 40 parts of silicone beads (Toshiba Silicone Co., Ltd .: Tospearl average particle diameter 2 μm) and diffusion penetrant (E2) (Sanyo Chemical Industries Co., Ltd .: NAROACTY ID50) 0.4 After mixing and kneading for 5 minutes at 25 ° C in a mincing machine (diameter hole diameter: 6mm, Iizuka Kogyo Co., Ltd. 12VR-400K), aeration type under conditions of 135 ° C and wind speed of 2.0m / sec. It dried with the band dryer and obtained the polymer dried material.
This polymer dried product was pulverized with a commercially available juicer mixer and adjusted to a particle size of 250 to 600 μm using a sieve having an opening of 600 and 250 μm, and then 100 parts of this was stirred at a high speed (high speed stirring turbine manufactured by Hosokawa Micron). 2 parts of a 10% water / methanol mixed solution of ethylene glycol diglycidyl ether (weight ratio of water / methanol = 70/30) was added while spraying and mixing. The absorbent resin particle (11) was obtained by standing still for minutes and carrying out heat crosslinking.

<Example 12>
Absorbent resin particles (12) were obtained in the same manner as in Example 11 except for using a pulverized product of polyethylene film (a polyethylene film manufactured by Tamapoly Co., Ltd., having a thickness of 30 μm and an opening of 250 μm) instead of silicone beads. .

<Example 13>
400 parts of a hydrogel polymer (AA-1), 40 parts of a wax emulsion (trade name Chemipearl S650, manufactured by Mitsui Chemicals, Inc.) and a diffusion penetrant (E2) (manufactured by Sanyo Chemical Industries, Ltd .: NAROACTY ID50) 0.4 Part, and kneaded for 5 minutes at 25 ° C in a minced machine (diameter hole diameter: 6mm, 12VR-400K manufactured by Iizuka Kogyo Co., Ltd.), and then ventilated band under conditions of 135 ° C and wind speed of 2.0m / sec. It dried with the dryer and obtained the polymer dried material.
This polymer dried product was pulverized with a commercially available juicer mixer and adjusted to a particle size of 30 to 60 mesh using a sieve having a mesh opening of 590 and 250 μm, and then 100 parts of this was stirred at a high speed (a high-speed stirrer made by Hosokawa Micron). 2 parts of a 10% water / methanol mixed solution of ethylene glycol diglycidyl ether (water / methanol weight ratio = 70/30) was added while spraying and mixing at 140 ° C. Absorbent resin particles (13) were obtained by standing still for 30 minutes and crosslinking by heating.

<Example 14>
Absorbent resin particles (14) were obtained in the same manner as in Example 13, except that 40 parts of the wax emulsion was replaced with 1.7 parts.

<Example 15>
Except for replacing 40 parts of the wax emulsion with 0.14 parts and using 0.4 parts of the diffusion penetrating agent (E1) (manufactured by Sanyo Chemical Industries, Ltd .: Sanmorin OT70) with 0.14 parts, In the same manner as in Example 13, absorbent resin particles (15) were obtained.

<Example 16>
In a glass reaction vessel, 77 parts of sodium acrylate, 22.85 parts of acrylic acid, 0.15 part of N, N′-methylenebisacrylamide and 293 parts of deionized water, 0.001 part of dichlorotris (triphenylphosphine) ruthenium Then, 0.2 part of a hydrophobic substance (C11) (manufactured by Sanyo Chemical Industries, Ltd .: NAROACTY ID20: nonionic surfactant) was 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 part of 2% aqueous solution of amidinopropane dihydrochloride, polymerization is started and the temperature reaches 80 ° C., and then polymerized at a polymerization temperature of 80 ± 2 ° C. for about 5 hours to form a crosslinked polymer (A2) A hydrogel polymer (AA-2) comprising: To 400 parts of this hydrogel polymer (AA-2), 0.4 parts of diffusion penetrant (E2) (Sanyo Kasei Kogyo Co., Ltd .: NAROACTY ID50) is added, and a mincing machine (hole diameter of the eye plate: 6 mm, Iizuka After being kneaded at 25 ° C. for 5 minutes using a 12VR-400K manufactured by Kogyo Co., Ltd., 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 polymer product.
The polymer dried product was pulverized with a commercially available juicer mixer, adjusted to a particle size of 250 to 600 μm using a sieve having an opening of 600 and 250 μm, and then 100 parts of this polymer was stirred at a high speed (high speed stirring turbulizer manufactured by Hosokawa Micron). 2 parts of a 10% water / methanol mixed solution of ethylene glycol diglycidyl ether (water / methanol weight ratio = 70/30) while being sprayed and mixed, and mixed at 140 ° C. for 30 minutes. The absorbent resin particle (16) was obtained by standing still and heat-crosslinking.

<Example 17>
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. In this solution, 0.09 part of ethylene glycol diglycidyl ether (manufactured by Nagase Chemical Industries, Denacol EX-810), 0.0146 part of sodium hypophosphite monohydrate, 0.0727 part of potassium persulfate and Diffusion penetrant (E1) (Sanyo Kasei Kogyo Co., Ltd .: Sanmorin OT70) 0.57 part is added and dissolved, 8.5 parts of (DD15) material is added, and a biomixer (ABM, Nippon Seiki Co., Ltd.) is added. -Type 2), the mixture was stirred and dispersed for 2 minutes to obtain a monomer aqueous solution. 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: (Blysurf A210G) 1.56 parts was added and dissolved, and then purged with nitrogen while stirring, and then heated to 70 ° C. Then, while maintaining the temperature at 70 ° C., the adjusted monomer aqueous solution was dropped at 6.6 parts / minute for 6 minutes and held at 75 ° C. for 15 minutes, and then the remaining monomer aqueous solution was added at 6.6 parts / minute for 54 minutes. It was dripped over. 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, the resin particles settled, and the resin particles and cyclohexane were separated by decantation, and 80 parts of the resin particles and 140 parts of cyclohexane were placed in a reaction vessel, and glycerin polyglycidyl ether was added thereto. (Nagase Kasei Kogyo Co., Ltd., trade name: Denacol EX-314) After adding 3.4 parts of cyclohexane solution containing 0.4%, heating at 60 ° C. and holding for 30 minutes, further heating to reflux cyclohexane Then, the resin particles were obtained by filtration and dried under reduced pressure at 80 ° C. to obtain absorbent resin particles (17).

<Example 18>
Absorbent resin particles (18) were obtained in the same manner as in Example 17, except that the material (DD16) was used instead of the material (DD15).

<Example 19>
Absorbent resin particles (19) were obtained in the same manner as in Example 17, except that a wax emulsion (trade name Chemipearl S650, manufactured by Mitsui Chemicals, Inc.) was used instead of the material (DD15).

<Example 20>
The amount used of the material (DD15) 8.5 parts is replaced with 3.5 parts, and the amount of the diffusion penetrant (E1) (Sanyo Kasei Kogyo Co., Ltd .: Sanmorin OT70) used 0.57 parts is replaced with 0.17 parts. Absorbent resin particles (20) were obtained in the same manner as Example 17 except that.

<Comparative Example 1>
Comparative absorbent resin particles (1 ′) were obtained in the same manner as in Example 1 except that the material (D) and the diffusion penetrant (E1) were not added to the hydrogel polymer (AA-1).

<Comparative example 2>
Comparative absorbent resin particles (2 ′) were obtained in the same manner as in Example 1 except that only the diffusion penetrant (E1) was not added to the hydrogel polymer (AA-1).

<Comparative Example 3>
Comparative absorbent resin particles (3 ′) were obtained in the same manner as in Example 1 except that pulp (Nippon Paper Chemical Co., Ltd. product: KC Flock W-400G) was used instead of the material (DD12).

<Comparative example 4>
Comparative absorbent resin particles (4 ′) were obtained in the same manner as in Example 1 except that silica (Nihon Aerogel product: Aerogel 200PE) was used instead of the material (DD13).

<Comparative Example 5>
Comparative absorbent resin particles (5 ′) were obtained in the same manner as in Example 17 except that the material (DD15) and the diffusion penetrant (E1) (Sanmorin OT70) were not added.

<Comparative Example 6>
Comparative absorbent resin particles (6 ′) were obtained in the same manner as in Example 17 except that the material (DD15) was not added.

<Comparative Example 7>
Comparative absorbent resin particles (7 ′) were obtained in the same manner as in Example 17, except that pulp (Nippon Paper Chemicals Co., Ltd. product: KC Flock W-400G) was used instead of the material (DD15).

<Comparative Example 8>
Comparative absorbent resin particles (8 ′) were obtained in the same manner as in Example 17 except that silica (Nippon Aerogel product: Aerogel 200PE) was used instead of the material (DD15).

  Absorption amount under diffusion of absorbent resin particles (1) to (20) and comparative absorbent resin particles (1 ′) to (8 ′) (Q) {As a metering pump, a dripping pump manufactured by Sakai Sangyo Co., Ltd., trade name CP- 21 was used. }, Evaluation of the results of evaluating the water retention amount (X), the liquid passing rate under load (Y), and the absorption time (min) (Z) until reaching the saturation volume of 70% in physiological saline by the above method The results are shown in Tables 1 and 2.

<Example 21>
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. Then, pressing was performed at a pressure of 5 kg / cm ² for 30 seconds to obtain an absorbent body (B1) of Example 13. The obtained absorbent body (B1) is cut into a rectangle of 14 cm × 36 cm, and water absorbent paper (basis weight 15.5 g / m ² ) having the same size as the absorbent body is arranged above and below each of the absorbent bodies (B1). A disposable diaper (1) was prepared by placing a polyethylene sheet used on the back side and a polyethylene non-woven fabric (basis weight 20.0 g / m ² ) on the surface.

<Examples 22 to 40>
Similarly, absorbent bodies (B2) to (B20) are prepared using the absorbent resin particles (2) to (20) instead of the absorbent resin particles (1), and further the paper diapers (2) to (20). It was created.

<Example 41>
After forming a layer of 50 parts of fluff pulp, 100 parts of the absorbent resin particles (2) obtained in Example 2 are uniformly dispersed, and a layer of 50 parts of fluff pulp is further laminated thereon to form a sandwich structure. The absorber (B21) was obtained by pressing at a pressure of 5 kg / cm ² for 30 seconds. The obtained absorbent body (B21) is cut into a 14 cm × 36 cm rectangle, and water absorbent paper (basis weight: 15.5 g / m ² ) having the same size as the absorbent body is arranged above and below each of the absorbent bodies (B21). The disposable diaper (21) was created by arrange | positioning the polyethylene sheet currently used on the back surface and the nonwoven fabric made from polyethylene (basis weight 20.0g / m < ² >) on the surface.

<Comparative Examples 9-16>
A comparative absorbent ( B1 ′) to (B8 ′) were prepared, and disposable diapers (1 ′) to (8 ′) were prepared.

  About the created paper diapers (1) to (21) and (1 ′) to (8 ′), the amount of absorption until leakage and the surface dryness were measured by the following method, and the surface dryness value by SDME was measured by the above method, The measurement results are shown in Table 3.

<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 is fixed in a state of being inclined at 45 degrees so that one end (upper end) to which the diaper is fixed becomes the upper part. 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%) were added at a rate of 100 g / min with a dropping pump (manufactured by Sakai Sangyo Co., Ltd., trade name CP-21). The point in time when artificial urine leaked from the lower end of the disposable diaper was taken as the end point, the amount of artificial urine charged until it leaked was determined, and this was taken as the amount of absorption until leakage.

<Dry surface>
Using the paper diaper after measuring the amount of absorption until leakage, the dry feeling of the surface of the paper diaper was determined by touching with 10 panelists and evaluated in the following four stages. The average of 10 persons was calculated | required and it was set as the surface dry feeling.
○: Good dry feeling △: Slightly damp but satisfactory level of dry feeling ×: Poor dry feeling, damp or wet, no dry feeling

The absorbent resin particle of the present invention can be made into an absorbent article in which the liquid to be absorbed is difficult to be absorbed by being applied to various absorbers. In particular, hygiene of 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) It is 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.

It is the front sectional view showing typically the measuring device for measuring the amount of absorption under diffusion. It is the perspective transmission figure which showed typically the measuring apparatus for measuring the amount of absorption under diffusion.

Explanation of symbols

1 Wire mesh 2 Cylinder 3 Measurement sample 4 Input tube 5 Disc 6 Ring weight

Claims (12)

A water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) which becomes (a1) by hydrolysis and a crosslinked polymer (A) having an internal crosslinking agent (b) as essential constituent units and a hydrophobic substance (C); Absorbent resin particles comprising the absorbent resin particles, wherein the absorbent resin particles have a structure including part or all of (C). The structure comprising a part or all of the hydrophobic substance (C) inside the absorbent resin particles is a structure comprising a connecting part (RC) comprising (C) inside the absorbent resin particles. Item 10. Absorbent resin particles according to Item 1. The structure comprising a part or all of the hydrophobic substance (C) inside the absorbent resin particles has a hydrophobic substance (on the whole or part of the surface of the hydrophilic material (d1) or the hydrophobic material (d2)). The absorbent resin particle according to claim 1, wherein the absorbent resin particle has a structure comprising a material (D) coated or impregnated with C) inside the absorbent resin particle. The absorbent resin particle according to claim 1, wherein the hydrophobic substance (C) has an HLB value of 1 to 10. The absorbent resin particle according to claim 1, wherein the hydrophobic substance (C) is silicone or modified silicone. The absorbent resin particle according to claim 1, further comprising a diffusion penetrant (E) as a constituent component. The absorbent resin particle according to claim 1, which has an absorption amount under diffusion of 40 to 70 ml. The absorptive resin particle according to claim 1, wherein the absorption time (Z) until the saturation swelling degree in physiological saline reaches 70% by volume is 0.5 to 3.5 minutes. The absorptive resin particle of Claim 1 formed by satisfy | filling Formula (2) and (3).

In the formula, (X) is the water retention amount (g / g) of the absorbent resin particles after being immersed in physiological saline for 1 hour, and (Y) is 21 after the absorbent resin particles are immersed in physiological saline for 1 hour. The physiological saline flow rate (ml / min) under a load of 4 Pa. Moreover, (Z) is an absorption time (minute) until it reaches 70 volume% of the saturation swelling degree in physiological saline. Furthermore, the absorptive resin particle of Claim 9 formed by satisfy | filling Formula (4).

An absorbent comprising the absorbent resin particles according to claim 1 and a fibrous material. An absorbent article comprising the absorbent body according to claim 11.

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