JP2003165883A - Water-absorbing polymer and absorbing article using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-absorbing polymer well balanced in dryness and water-absorbing performance under pressure. <P>SOLUTION: This water-absorbing polymer comprises (A) a crosslinked polymer containing a (meth)acrylic acid (salt) as a main component and having ≤1.8 fractal order and (B) a surface modifier. It is preferable that the component B is a binding group capable of chemically bonding to the crosslinked polymer (A) and the surface tension of the component B is 10-30 dyne/cm and the component B is an organic compound (B1) having a hydrocarbon group which may have fluorine atom or a silicone compound (B2). This absorbing article is obtained by using the water-absorbing polymer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water-absorbent polymer and an absorbent article using the same. More specifically, it relates to a water-absorbing polymer that exhibits excellent water-absorbing performance and an absorbent article using the same.

[0002]

2. Description of the Related Art The higher the absorption capacity of a water-absorbent resin, the stronger the affinity of the water-absorbent resin with water. There has been a problem that uniform penetration into the entire water-absorbent resin particles is hindered. In order to solve this problem, it has been proposed to improve the dryness of the water-absorbent resin having an increased absorption capacity, and, for example, the water-absorbent resin particles and the like are known.

Water-absorbent resin particles obtained by mixing fine powdery hydrophobic silica having an average particle diameter of 0.05 μm or less and a specific surface area of 50 m ² / g or more (Patent Document 1). Water-absorbent resin particles obtained by adding inorganic powder such as hydrous silicon dioxide (white carbon, kaolin, clay, etc.), hydrous aluminum oxide, hydrous titanium oxide (Patent Document 2). Water-absorbent resin particles obtained by mixing stearic acid and inorganic powder and coating the surface with stearic acid (Patent Document 3).

[0004]

[Patent Document 1] JP-A-56-1333028

[Patent Document 2] JP-A-59-80459

[Patent Document 3] JP-A-63-105064

[0005]

However, in the above, although the dryness can be improved by adding the hydrophobic silica, the surface of the resin particles is covered with the hydrophobic silica, so that there is a problem that the absorption performance under pressure is deteriorated. Furthermore, since fine powdery silica is mixed, there is a problem that a large amount of dust is generated during the production of the water absorbent resin and the absorbent body. Further, in the above, when the inorganic powder is not hydrophobic (the same problem as in the case of the hydrophobic inorganic powder),
Although the absorption performance under pressure does not decrease so much, the dryness is insufficient, and further, since the inorganic powder is in the form of fine powder, a large amount of dust is generated as described above.
Further, in the above, there is a problem that the dryness is not sufficient, and the high-melting point organic compound and stearic acid impair the absorbability of the water-absorbent resin particles, so that the absorbency under load is lowered. As described above, in any case, it was difficult to balance the dryness and the absorption performance under pressure. That is, an object of the present invention is to provide a water-absorbing polymer having excellent water absorption performance under pressure and dryness.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the use of a specific water-absorbing polymer provides excellent water absorption under pressure and excellent dryness. The invention was reached. That is, the present invention is characterized by comprising a cross-linked polymer (A) having (meth) acrylic acid (salt) as a main constituent unit and a fractal order of 1.80 or less, and a surface modifier (B). And a water-absorbent polymer and an absorbent article using the same.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION (Meth) acrylic acid (salt) means acrylic acid, methacrylic acid, acrylic acid salt and methacrylic acid salt. As acrylate and methacrylate, alkali metal of acrylic acid or methacrylic acid (for example, lithium, potassium and sodium)
Salts, alkaline earth metal (eg, magnesium and calcium, etc.) salts, ammonium salts and the like are used. Of these, alkali metal salts are preferable, sodium salts, lithium salts and potassium salts are more preferable, sodium salts and lithium salts are particularly preferable, and sodium salts are most preferable.

If the cross-linked polymer (A) has (meth) acrylic acid (salt) as a main constituent unit, (meth)
It is possible to copolymerize acrylic acid (salt) with another vinyl monomer that is copolymerizable. Other copolymerizable vinyl monomers include, but are not limited to, copolymerizable monomers (hydrophilic vinyl monomers and hydrophobic vinyl monomers) and crosslinkable monomers.

The hydrophilic vinyl monomer is not particularly limited, but a vinyl monomer having at least one water-soluble group can be used. Examples of the water-soluble group, such as carboxyl (salt) group (-CO ₂ M), (poly) oxyethylene group _{{- (CH 2 CH 2 O} ) n-H}, sulfo (salt) group (-SO ₃ M ), a group consisting of a sulfonic acid ester (salt) (-OSO ₃ M), phosphono (salt) group (-PO (O
M) ₂ ), hydroxyl group (—OH), amino group (—NR ₂ ), amide group (—CONR ₂ ), primary ammonio group (—N ⁺ H ₃ ), secondary ammonio group (—N) ⁺ RH ₂ ), a tertiary ammonio group (—N ⁺ R ₂ H) and a quaternary ammonium salt group (—NR ₃ X) (quaternary ammonio group:
—N ⁺ R ₃ ) and the like. In addition, M represents a hydrogen atom, an alkali metal, an alkaline earth metal, or ammonium, R represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms which may contain a hetero atom, and X represents a counter ion (for example, Fluorine ion, chlorine ion, bromine ion, sulfate ion, methosulfate, nitrate ion, perchlorate ion, hydrogen sulfate ion, paratoluenesulfonate ion, oxalate ion, acetate ion, malate ion, citrate ion and tartrate ion Etc.), and n represents an integer of 1 to 30.

As the hydrophilic vinyl monomer, for example,
The following (i) anionic vinyl monomer, (ii) nonionic vinyl monomer, and (iii) cationic vinyl monomer are used. (I) an anionic vinyl monomer (i-1) monomers of monomer 4 to 30 carbon atoms can be used with a carboxyl (salt) group (-CO ₂ M), for example, unsaturated monocarboxylic acids (e.g., crotonic acid And cinnamic acid); unsaturated dicarboxylic acids (eg, maleic acid, fumaric acid, citraconic acid, itaconic acid, etc.); and monoalkyl (C 1-8) esters of the unsaturated dicarboxylic acids (eg, maleic acid mono). Butyl ester, fumaric acid monobutyl ester, maleic acid ethyl carbitol monoester, fumaric acid ethyl carbitol monoester, citraconic acid monobutyl ester, itaconic acid glycol monoester and the like).

(I-2) Sulfo (salt) group (-SO ₃ M)
A vinyl monomer having 2 to 30 carbon atoms can be used, and examples thereof include an aliphatic vinyl sulfonic acid or an aromatic vinyl sulfonic acid (for example, vinyl sulfonic acid, (meth) allyl sulfonic acid, styrene sulfonic acid and α-methyl). Styrene sulfonic acid, etc.); (meth) acrylic 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) acrylamido-2-hydroxypropanesulfonic acid); and alkyl (having 3 to 7 carbon atoms).
18) (Meth) allyl sulfosuccinate and the like.

(I-3) Sulfonate esterified product of vinyl monomer hydroxyalkyl (C 2-6) (meth) acrylate having a group (--OSO ₃ M) consisting of sulfonic acid ester (salt) {(meth) acryloyloxy Alkylsulfate} [for example, sulfuric acid esterified product of hydroxyethyl (meth) acrylate {(meth) acryloyloxyethylsulfate}, etc.]; poly (polymerization degree n = 2 to 30) oxyalkylene (wherein the alkylene group has 2 carbon atoms) 4, and the polymerization form is a single or random and / or block) sulfuric acid esterified product of mono (meth) acrylate [eg, poly (n = 5-15) oxypropylene monomethacrylate sulfuric acid esterified product];
And compounds represented by formula (1), (2) or (3).

[0013]

[Chemical 1]

[0014]

[Chemical 2]

[0015]

[Chemical 3]

In the general formulas (1) to (3), R represents a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. R'is a hydrogen atom, or a carbon atom which may be substituted with a fluorine atom.
Represents an alkyl group, an alkali metal, an alkaline earth metal or ammonium. AO represents an oxyalkylene group having 2 to 4 carbon atoms, and when n is 2 or more, two or more AOs may be the same or different, and if different, they may be random, block or a mixture thereof. Ar represents a benzene ring, and M represents a hydrogen atom, an alkali metal, an alkaline earth metal or ammonium. n represents an integer of 1 to 50.

(I-4) Phosphono (salt) group (--PO (O
M) ₂ ) having a vinyl monomer (meth) hydroxyalkyl acrylate (having 2 to 2 carbon atoms)
6) Phosphoric acid monoester {(meth) acryloyloxyalkyl (alkyl carbon number 2 to 6) phosphate}
[For example, monophosphate of hydroxyethyl (meth) acrylate {(meth) acryloyloxyethyl phosphate} and the like], phosphoric acid diester of hydroxyalkyl (meth) acrylate (having 2 to 6 carbon atoms) [eg, phenyl-2-acryloyl Roxyethyl phosphate, etc.] and alkyl (meth) acrylate (alkyl having 2 to 2 carbon atoms)
6) Phosphonic acid [eg, 2-acryloyloxyethylphosphonic acid] and the like can be mentioned.

(I-5) Vinyl monomer having the salt of (i-1) to (i-4) Alkali metal salt (sodium salt, potassium salt, etc.), alkaline earth metal salt (calcium salt, magnesium salt, etc.) ),
Ammonium salt [ammonium salt, tetraalkyl (alkyl having 1 to 8 carbon atoms) ammonium salt (for example, tetramethylammonium salt, trimethylethylammonium salt, tetraoctylammonium salt, etc.)], organic amine salt [having 2 to 8 carbon atoms] Alkanolamine salts (eg,
Monoethanolamine salt, diethanolamine salt, triethanolamine salt, tetraethanolammonium salt, etc.), polyalkylene (alkylene carbon number 1-8) polyamine (amino group number 2-10) (for example, diethylenetriamine, triethylenetetramine, etc.) or Derivatives thereof [alkylated products having 1 to 8 carbon atoms, 2 to 12 carbon atoms]
Alkylene oxide adduct (1 to 30 mol), etc.],
And a vinyl monomer having a salt such as a lower alkylamine having 1 to 4 carbon atoms] corresponding to the above vinyl monomer.

(Ii) Nonionic monomer (ii-1) vinyl monomer having hydroxyl group (-OH) monoethylenically unsaturated alcohol [eg (meth) allyl alcohol and (meth) propenyl alcohol]; and divalent A monoethylenically unsaturated carboxylic acid ester of a polyol having a valence of 6 or more (for example, an alkylene glycol having 2 to 20 carbon atoms, glycerin, polyalkylene (2 to 4 carbon atoms) glycol (molecular weight 106 to 2000), or the like) or Monoethylenically unsaturated ether [eg, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, triethylene glycol (meth) acrylate, poly-oxyethylene-
Oxypropylene (random and / or block) glycol mono (meth) allyl ether (the terminal hydroxyl group may be etherified or esterified), etc.] and the like.

(Ii-2) Vinyl monomer having a (poly) oxyethylene group {-(CH ₂ CH ₂ O) nH} A vinyl monomer having a (poly) oxyethylene group of n = 1 to 30 can be used. , 2-hydroxyl (meth) acrylate, diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, hexaethylene glycol mono (meth) acrylate, decaethylene glycol mono (meth) Examples thereof include acrylate, polyethylene glycol (degree of polymerization: 16) mono (meth) acrylate, maleic acid di (hydroxyethyloxyethyl) ester, and hexaethylene glycol mono (meth) propenyl ether.

(Ii-2) a group consisting of amide (--CON
R ₂₎ vinyl monomers (meth) acrylamide with, N- alkyl (carbon number 1
8) (Meth) acrylamide [eg, N-methylacrylamide etc.], N, N-dialkyl (C1-8)
Acrylamide [eg, N, N-dimethylacrylamide, N, N-di-n- or i-propylacrylamide, etc.], N-hydroxyalkyl (C 1 to C 8) (meth) acrylamide [eg, N-methylol (meta )
Acrylamide, N-hydroxyethyl (meth) acrylamide and the like]; N, N-dihydroxyalkyl (carbon number 1 to 8) (meth) acrylamide [eg, N, N-dihydroxyethyl (meth) acrylamide and the like] and vinyl lactam [eg. , N-vinylpyrrolidone, etc.] and the like.

(Ii-3) A vinyl monomer having an amino group (-NR ₂ ) Amino group-containing ester of monoethylenically unsaturated mono- or di-carboxylic acid, for example, dialkyl (having 1 to 8 carbon atoms).
Aminoalkyl (C2-10) (meth) acrylate, dihydroxyalkyl (C1-8) aminoalkyl (C2-10) (meth) acrylate and morpholinoalkyl (C1-8) (meth) acrylate Etc. [eg, dimethylaminoethyl (meth) acrylate, diethylamino (meth) acrylate, di (hydroxyethyl) aminoethyl (meth) acrylate, morpholinoethyl (meth) acrylate, dimethylaminoethyl fumarate, etc.]; monoethylenically unsaturated Amino group-containing amide of mono- or di-carboxylic acid, for example, dialkyl (C1-8) aminoalkyl (C2-10)
(Meth) acrylamide and the like [for example, dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide and the like]; Heterocyclic vinyl compound [for example, vinylpyridine such as 2-vinylpyridine and 4-vinylpyridine, N-vinyl Imidazole, N-vinylpyrrolidone and the like]; and diallylamine and the like.

The (iii) The cationic vinyl monomer (iii-1) a primary ammonio group (-N ⁺ H _3), second
A vinyl monomer (ii-3) having a primary ammonio group (-N ⁺ RH ₂ ) or a tertiary ammonio group (-N ⁺ R ₂ H) with a protonic acid (for example, hydrofluoric acid, hydrochloric acid, bromic acid, sulfuric acid). , Sodium hydrogensulfate, nitric acid, perchloric acid, methylsulfate, paratoluenesulfonic acid, oxalic acid,
Neutralized with acetic acid, malic acid, citric acid, tartaric acid, etc. (for example, dialkyl (C1-8) aminoalkyl (C2-10) (meth) acrylate / protonate, dihydroxyalkyl (carbon number) 1-8) Aminoalkyl (C2-10) (meth) acrylate / protonate, morpholinoalkyl (C1-8) (meth) acrylate / protonate, etc. [eg, dimethylaminoethyl (meth) acrylate] -Hydrochloride, diethylamino (meth) acrylate bromate, di (hydroxyethyl) aminoethyl (meth) acrylate-perchlorate, morpholinoethyl (meth) acrylate-acetate,
Dimethylaminoethyl fumarate, tartrate, etc.]; Dialkyl (C1 to C8) aminoalkyl (C2 to C1)
0) (meth) acrylamide / protonate, etc. [eg, dimethylaminoethyl (meth) acrylamide / sulfate, diethylaminoethyl (meth) acrylamide /
Oxalate, etc.]; 2-vinylpyridine / hydrofluoride, 4-vinylpyridine / hydrochloride, N-vinylimidazole / nitrate, N-vinylpyrrolidone / methylsulfate, etc.]; and diallylamine / hydrochloride, etc. Can be mentioned.

(Iii-2) Quaternary ammonium salt group (-NR ₃ X) (quaternary ammonio group: -N)
A vinyl monomer (ii-3) or (iii-1) having ⁺ R ₃ ) with an alkylating agent having 1 to 8 carbon atoms (for example, methyl chloride, ethyl bromide, dimethylsulfate, ethylene oxide, benzyl chloride and dimethyl carbonate). Quaternized with a quaternizing agent (for example, trimethylaminoethyl (meth) acrylate chloride, methyldiethylaminoethyl (meth) acrylate methosulfate, trimethylaminoethyl (meth) acrylamide chloride, diethylbenzylaminoethyl) (Meth) acrylamide chloride} and the like.

As the hydrophobic vinyl monomer, (iv)
Aromatic ethylenic monomer having 8 to 30 carbon atoms, (v) aliphatic ethylenic monomer having 2 to 20 carbon atoms, (vi) alicyclic ethylenic monomer having 5 to 15 carbon atoms, and (vi
i) (Meth) acrylic acid alkyl ester (having 4 to 50 carbon atoms in the alkyl group) and the like can be used. Examples of (iv) aromatic ethylenic monomers include styrene, α-methylstyrene, vinyltoluene, hydroxystyrene, vinylnaphthalene, and dichlorostyrene. (V)
Examples of the aliphatic ethylenic monomer include alkenes [ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.] and alkadienes [butadiene, isoprene, etc.] and the like. Examples of (vi) alicyclic ethylenic monomers include monoethylenically unsaturated monomers [pinene, limonene, indene, etc.] and polyethylene vinyl polymerizable monomers [cyclopentadiene, bicyclopentadiene, ethylidene norbornene, etc.] and the like. Examples of (vii) (meth) acrylic acid alkyl ester include n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate and eicosyl (meth). ) Acrylate and the like.

These copolymerizable monomers may be used either individually or in combination of two or more. Of these, hydrophilic vinyl monomers are preferable, and (i) anionic vinyl monomers and (ii) nonionic vinyl monomers,
Particularly preferably, (i-1) carboxyl (salt) group (-C
O ₂ M) monomer having, (i-2) sulfo (vinyl monomer and a sulfonate) group (-SO ₃ M) (II-
Vinyl monomers having 2) consisting of an amide group (-CONR _2), more particularly preferably (ii-2) a vinyl monomer having made of amide (-CONR _2), most preferably (meth) acrylamide.

When a copolymerizable monomer is used, the content (% by weight) of the copolymerizable monomer unit is preferably 0.001 to 10 based on the weight of the (meth) acrylic acid (salt) unit. , More preferably 0.05 to 7, particularly preferably 0.03 to 5, and most preferably 0.01 to 3. That is, in this case, the content (% by weight) of the copolymerizable monomer unit is preferably 0.001 or more, and more preferably 0.001 or more based on the weight of the (meth) acrylic acid (salt) unit.
05 or more, particularly preferably 0.03 or more, most preferably 0.01 or more, and preferably 10 or less, more preferably 7 or less, particularly preferably 5 or less, most preferably 3 or less.

Examples of the crosslinkable monomer include a crosslinker having two or more ethylenically unsaturated groups, a crosslinker having an ethylenically unsaturated group and a reactive functional group, and two or more reactive functional groups. The cross-linking agent and the like that it has can be used. The ethylenically unsaturated group means a double bond structure between carbon atoms, and vinyl, (meth) acryloyl, allyl, propenyl and the like are used. The reactive functional group means a functional group capable of reacting with a carboxyl group, such as glycidyl, isocyanato, and N-.
Methylol, hydroxyl group and the like are used.

Examples of the cross-linking agent having two or more ethylenically unsaturated groups include N, N'-methylenebis (meth).
Acrylamide, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, glycerin (di or tri) acrylate, trimethylolpropane triacrylate, diglycerin (di, tri or tetra) ( (Meth) acrylate, pentaerythritol (di, tri or tetra) (meth) acrylate, triallylamine, triallyl cyanurate, triallyl isocyanurate, tetraallyloxyethane, pentaerythritol (di, tri or tetra) allyl ether, divinylbenzene , Diallyloxybenzene, dipropenyloxybenzene, triallyloxybenzene and diallylbenzene.

Examples of the cross-linking agent having an ethylenically unsaturated group and a reactive group include glycidyl (meth) acrylate, isocyanatoethyl (meth) acrylate, glycidyl vinyl ether, glycidyl allyl ether and N-methylol (meth) acrylamide. Etc.

Examples of the cross-linking agent having two or more reactive functional groups include ethylene glycol, diethylene glycol, glycerin, propylene glycol, diethanolamine, trimethylolpropane, polyethyleneimine, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether and propylene. Examples thereof include glycol diglycidyl ether and glycerin (di or tri) glycidyl ether.

These crosslinking agents may be used either individually or in combination of two or more. Of these, the ethylenically unsaturated group is 2
A cross-linking agent having one or more is preferable, and more preferably N,
N'-methylenebis (meth) acrylamide, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, glycerin (di or tri) acrylate, trimethylolpropane triacrylate, diglycerin ( Di, tri or tetra) (meth) acrylate, pentaerythritol (di, tri or tetra) (meth) acrylate, triallylamine, triallyl cyanurate, triallyl isocyanurate, tetraallyloxyethane, pentaerythritol (di, tri or Tetra) allyl ether, divinylbenzene, diallyloxybenzene, dipropenyloxybenzene, triallyloxybenzene and diallylbenzene, particularly preferably N, N′-methyl. Down bisacrylamide, ethylene glycol diacrylate, trimethylol propane triacrylate, tetra allyloxy ethane, pentaerythritol allyl ether and triallyl amine.

When the crosslinkable monomer is used, the content (% by weight) of the crosslinkable monomer unit is preferably 0.001 to 10 based on the weight of the (meth) acrylic acid (salt) unit. , More preferably 0.005 to 5, particularly preferably 0.007 to 1, and most preferably 0.01 to 1. That is, in this case, the content (% by weight) of the crosslinkable monomer unit is preferably 0.001 or more, more preferably 0.005 or more, based on the weight of the (meth) acrylic acid (salt) unit. It is particularly preferably 0.007 or more, most preferably 0.01 or more, preferably 10 or less, more preferably 5 or less, particularly preferably 1 or less, most preferably 1 or less.

The fractal order of the crosslinked polymer (A) is
1.8 or less, preferably 1.8 to 0.1, more preferably 1.8 to 1.0, and particularly preferably 1.8 to
1.2, even more preferably 1.8 to 1.4, most preferably 1.8 to 1.6. When the fractal order is in this range, only the surface area can be increased without reducing the particle size, which is preferable.

The fractal order is one of the indexes showing the shape of particles and represents the degree of unevenness on the particle surface. A small fractal order means that the particles have many surface irregularities and a large specific surface area. On the other hand, if the resin particles are true spheres having no irregularities on the surface, the fractal order is 2.
Increasing the specific surface area is effective for increasing the water absorption rate of the water-absorbent polymer. The specific surface area can be increased by decreasing the particle size or increasing the surface irregularities. However, the particle size of the water-absorbent polymer is largely regulated by its use, and further, when the particle size is reduced, the adhesiveness between the particles is increased and the permeability to the entire water-absorbent polymer is impaired. There is a limit to reducing the specific surface area to increase the specific surface area, and it is desirable to increase the specific surface area by increasing the unevenness of the surface.

The fractal order is determined as follows. A scanning electron micrograph of the crosslinked polymer (A) particles,
Images are taken at 20, 40, 80, 150 and 300 times magnification. The grain contour length and grain projected area are obtained for each of these photographs. The points obtained from each photograph are plotted on the XY coordinates with the common logarithm of the grain outline length as the X-axis and the common logarithm of the grain projection area as the Y-axis, and the straight line passing through the points is found by the least squares method. The slope of the straight line drawn by the least-squares method is taken as the fractal order, and the average value of five randomly sampled particles is taken as the fractal order.

The crosslinked polymer (A) can be obtained by, for example, stirring in a hydrophobic organic solvent with (meth) acrylic acid (salt), and optionally other copolymerizable vinyl monomer, polymerization initiator and chain transfer. It can be produced by continuously supplying the agent and / or the graft base material and carrying out reverse phase suspension polymerization (JP-A No. 13-2935, etc.). As the hydrophobic organic solvent, any conventionally known organic solvent can be used as long as it is an organic solvent that is hardly soluble in water, for example, having 5 carbon atoms.
To hydrocarbons (pentane, cyclohexane, normal hexane, normal heptane, toluene, xylene and octadecane). When a hydrophobic organic solvent is used, the amount used is 50 to 50% based on the weight of water.
1000% by weight is preferable, and more preferably 100 to
It is 600% by weight, particularly preferably 200 to 400% by weight. That is, in this case, the amount (% by weight) of the hydrophobic organic solvent used is preferably 50 or more, more preferably 100 or more, and particularly preferably 20 based on the weight of water.
It is 0 or more, preferably 1000 or less, more preferably 600 or less, and particularly preferably 400 or less. As the water, ion-exchanged water is preferable.

The polymerization initiator is not particularly limited and conventionally known ones can be used. For example, an azo type initiator, a peroxide type initiator, a redox type initiator and an organic halogen compound initiator can be used. Examples of the azo initiator include azobisisobutyronitrile, azobiscyanovaleric acid and salts thereof, 2,2′-azobis (2-amidinopropane) hydrochloride and 2,2′-azobis (2-methyl-N). -(2-hydroxyethyl) propionamide, etc. Examples of the peroxide-based initiator include:
Inorganic peroxides [eg hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate, etc.], organic peroxides [eg benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, succinic acid] Peroxide and di (2-ethoxyethyl) peroxydicarbonate and the like] and the like. Examples of redox initiators include reducing agents such as alkali metal sulfites or bisulfites, ammonium sulfite, ammonium bisulfite, ferric chloride, ferric sulfate and / or ascorbic acid, and alkali metal peroxides. Examples thereof include those which are combined with an oxidizing agent such as a sulfate, ammonium persulfate, hydrogen peroxide and / or an organic peroxide. The organic halogen compound initiator is a halogenated alkyl, halogenated alkyl phenyl ketone, halogenated alkyl carboxylic acid, and halogenated alkyl carboxylic acid alkyl ester selected from the group consisting of 1 to 10 or more halogens and 1 to 1 carbon atoms. Fifteen or more organic halogen compounds are used, and examples thereof include tetrachloromethane, trichlorobromomethane, trichloroiodomethane, dichloromethylphenyl ketone, 1-bromo-1-methylethylcarboxylic acid, and an alkyl group having 1 to 1 carbon atoms. 1-Bromo-1-methylethylcarboxylic acid alkyl ester of 8 (for example, methyl 1-bromo-1-methylethylcarboxylic acid,
Ethyl 1-bromo-1-methylethylcarboxylate, 1-
Bromo-1-methylethylcarboxylate octyl and 1-
Bromo-1-methylethylcarboxylic acid lauryl) and the like.

These initiators may be used alone or in combination of two or more. Among these, azo type initiators, redox type initiators and a combination thereof are preferable.
When the polymerization initiator is used, the amount (% by weight) of the polymerization initiator used is 0.00 based on the total weight of all the monomers {(meth) acrylic acid (salt) and other vinyl monomers}.
5 to 0.5 is preferable, and more preferably 0.007 to
0.4, particularly preferably 0.009 to 0.3. That is, in this case, the amount of the polymerization initiator used (% by weight) is
Based on the total weight of all the monomers, it is preferably 0.005 or more, more preferably 0.007 or more, particularly preferably 0.009 or more, and preferably 0.5 or less,
It is more preferably 0.4 or less, and particularly preferably 0.3 or less.

As the graft base material, natural sugars such as starch and cellulose (potato starch, corn starch, rice starch, etc.) or modified products thereof (pregelatinized starch, oxidized starch, hydroxyethyl cellulose, etc.)
Alkyl ether cellulose, carboxyalkyl cellulose, etc.) Monovalent alcohol alkylene oxide adducts (methanol ethylene oxide adducts, ethanol ethylene oxide adducts, partially dispersed alcohol ethylene oxide adducts, etc. Carbon number of the monohydric alcohol Is preferably 1 to 5, and the alkylene group of the alkylene oxide preferably has 2 to 4 carbon atoms),
Polyvinyl alcohol (partially saponified water-soluble polyvinyl alcohol is preferred, and the saponification degree is 50 mol% to 10
Water-soluble polyvinyl alcohol having a degree of polymerization of about 200 to 1000 at 0 mol% is more preferable), and polyester (di- or tri-methacrylic acid ester of polyol (ethylene glycol, trimethylolpropane, glycerin, etc.), unsaturated polyester (the above-mentioned. Water-soluble or water-dispersible synthetic resins such as those obtained by reacting a polyol with an unsaturated fatty acid such as maleic acid). When a graft base material is used, the content (% by weight) of the graft base material is preferably 0.1 to 3.0, more preferably 0.3 to 2. based on the total weight of all the monomers. 7, particularly preferably 0.5 to 2.0. That is, in this case, the content (% by weight) of the graft base material is preferably 0.1 or more, more preferably 2.7 or more, and particularly preferably 0.5, based on the total weight of all the monomers. Or more, and preferably 3.0 or less,
It is more preferably 2.7 or less, and particularly preferably 2.0 or less.

As the chain transfer agent, pyrogallol, p-
Methoxyphenol, gallic acid, gallic acid ester, tannic acid, flavonoids, thiourea, etc., may be used alone or in combination of two or more kinds. When a chain transfer agent is used, the added amount (% by weight) of the chain transfer agent is preferably 0.001 to 30 and more preferably 0.05 to 20 based on the weight of (meth) acrylic acid (salt). , Particularly preferably 0.1 to 10. That is, in this case, the addition amount (% by weight) of the chain transfer agent is preferably 0.001 or more, more preferably 0.05 or more, and particularly preferably 0, based on the weight of the (meth) acrylic acid (salt). 0.1 or more, preferably 30 or less, more preferably 20 or less, particularly preferably 10 or less.

In the reverse phase suspension polymerization, a conventionally known dispersant (eg, sucrose ester dispersant, phosphate ester dispersant, sorbitan dispersant) is used, and a mixture of at least one of these is used. The polymerization can be carried out below. When a dispersant is used, the amount (% by weight) of the dispersant used is preferably 0.001 to 10, more preferably 0.005 to 8, and particularly preferably 0.005 based on the weight of the hydrophobic organic solvent. It is 01-5. That is, in this case, the amount (% by weight) of the dispersant used is preferably 0.001 or more, and more preferably 0.001 or more, based on the weight of the hydrophobic organic solvent.
It is 005 or more, particularly preferably 0.01 or more, and preferably 10 or less, more preferably 8 or less, and particularly preferably 5 or less.

The reverse phase suspension polymerization is preferably carried out in two steps. By carrying out in two steps, the fractal order of the crosslinked polymer (A) tends to be 1.8 or less. First
In the reverse phase suspension polymerization of the stage (hereinafter, abbreviated as prior suspension polymerization), for example, a part of the monomer aqueous solution is supplied to the suspension organic polymerization in a hydrophobic organic solvent containing a dispersant.
The aqueous monomer solution is a solution of (meth) acrylic acid (salt) and, if necessary, other vinyl monomer, a graft base material, a polymerization initiator and / or a chain transfer agent dissolved in the total amount of water required for the polymerization. is there. The amount of water (weight ratio) required for the polymerization is usually 0.1 to the hydrophobic organic solvent.
2.0, preferably 0.3 to 1.3. That is,
The amount of water (weight ratio) is usually 0.
1 or more, preferably 0.3 or more, and usually 2.0
The following is preferably 1.3 or less.

In this suspension polymerization, it is possible to supply a predetermined amount of monomer aqueous solution into a hydrophobic organic solvent and then raise the temperature to carry out polymerization (batch supply polymerization), but this is maintained under polymerization conditions. It is preferable to carry out suspension polymerization (sequential supply polymerization) while successively supplying an aqueous monomer solution into a hydrophobic organic solvent. In this preliminary suspension polymerization, it is preferable to control the supply rate and stirring strength of the monomer aqueous solution so that the monomer aqueous solution is dispersed as fine droplets (diameter of about 1 to 9 μm). The concentration (% by weight) of the aqueous monomer solution to be subjected to this preliminary suspension polymerization is preferably 0.1 to 40, and more preferably 1 to 25, based on the weight of the total aqueous monomer solution.

Following the preceding suspension polymerization, a second-stage reverse phase suspension polymerization is carried out. In the second stage suspension polymerization, the polymerization rate of the monomer used in the preceding suspension polymerization is at least 10% by weight.
To reach after. For that purpose, preferably 3 minutes or more, particularly preferably 5 minutes or more after the supply of the aqueous monomer solution in the preceding reverse phase suspension polymerization is completed,
It is preferred to initiate the second stage reversed phase suspension polymerization. Since the productivity tends to decrease when this time is long, the time is preferably 60 minutes or less at the longest, more preferably 30 minutes or less. The polymerization rate here is weight% with respect to the charged monomer amount of the produced polymer. That is, {(weight of charged monomer)-(weight of residual monomer)} × 100 / (weight of charged monomer).

The suspension polymerization in the second stage is carried out by maintaining the hydrophobic organic solvent containing the polymer produced in the preceding suspension polymerization under the polymerization conditions and successively supplying the remaining monomer aqueous solution thereto. The supply of the aqueous monomer solution in the second stage suspension polymerization is at least 10% or more (preferably 40% or more, particularly preferably 6%) of the total polymerization time of the second stage.
0% or more). The total polymerization time is the time until the degree of polymerization (polymerization rate) of the resin particles produced from the initiation of the second stage polymerization reaches 98% by weight, preferably 98.5% by weight, or the polymerization operation is terminated. Means the shorter of the time to. The total polymerization time varies depending on the type of the initiator and the like, but is usually 2 to 8 hours.

In both the preceding reversed phase suspension polymerization and the second-stage reversed phase suspension polymerization, the aqueous monomer solution is usually fed continuously at a constant rate, but the feeding rate may be changed if desired. In addition, the supply of the monomer aqueous solution can be interrupted midway. In the suspension polymerization of the second stage, the fed monomer aqueous solution is absorbed by the polymer already present in the hydrophobic organic solvent to grow it, or the polymer produced from the fed monomer aqueous solution is already absorbed. It is considered that the particles grow by coalescing with the existing polymer. Therefore, the feed rate and stirring strength of the monomer aqueous solution are
It is preferable to carry out so that the aqueous monomer solution is sufficiently dispersed. Generally, it is preferable to maintain the stirring state of the pre-suspension polymerization, and more preferably, in the pre-suspension polymerization, (meth) acrylic acid (salt) and optionally other vinyl monomers copolymerizable with each other are formed into fine droplets (diameter). About 1-9 μm)
Is to maintain the stirring strength controlled so as to disperse as.

If desired, the aqueous monomer solution and a portion of the hydrophobic organic solvent may be premixed and then fed into the hydrophobic organic solvent maintained under the polymerization conditions. The polymerization reaction is usually carried out at 40 to 150 ° C, though it depends on the polymerization initiator. If the temperature is too high, the self-crosslinking becomes active, and the water absorption performance of the polymer produced is deteriorated. On the other hand, if the temperature becomes too low, not only the polymerization takes a long time, but also sudden polymerization may be caused to form a lump. A suitable polymerization temperature is 60 to 90 ° C., and it is particularly preferable to carry out under reflux conditions of a hydrophobic organic solvent.

The monomer concentration of the aqueous monomer solution (% by weight), that is, the ratio of the total monomer weight to the weight of the aqueous monomer solution (weight of total monomer / weight of aqueous monomer solution:
%), Preferably 10 to 45, more preferably 12 to 40, and particularly preferably 15 to 35.
That is, the monomer concentration of the aqueous monomer solution (% by weight)
Is preferably 10 or more, more preferably 12 or more,
It is particularly preferably 15 or more, preferably 45 or less, more preferably 40 or less, particularly preferably 35 or less. In addition, all the monomers mean (meth) acrylic acid (salt), a copolymerization monomer, and a crosslinkable monomer. Within this range, in addition to being efficient in removing water later, the side chains such as self-crosslinking do not occur and the molecular weight distribution of the main chain is narrowed, and the absorption capacity of the finally obtained water-absorbent polymer is increased. Is more preferred, which is preferable.

Further, the crosslinked polymer (A) can be subjected to a surface crosslinking treatment with a surface crosslinking agent, if necessary. Cross-linking the surface of the particles of (A) with a surface cross-linking agent is preferable because the water absorption rate is further improved and the water absorption amount under pressure is further increased. In the case where the surface cross-linking treatment is carried out, the polymer before the surface cross-linking treatment is referred to as a pre-surface cross-linking polymer (A ′) in order to distinguish it from the cross-linked polymer (A) after the surface cross-linking treatment.

The surface cross-linking agent is, for example, JP-A-59.
-189103 and the like, polyvalent glycidyl, JP-A-58-180233 and JP-A-61-1690.
Polyhydric alcohols, polyhydric amines, polyhydric aziridines and polyhydric isocyanates described in JP-A No. 3-21, JP-A-61-21.
1305 and JP-A-61-252212, and other silane coupling agents, and JP-A-51-1
Examples thereof include polyvalent metals described in JP-A-36588 and JP-A-61-257235. Among these surface cross-linking agents, a water-absorbing polymer that forms a strong covalent bond with a carboxyl (salt) group and is excellent in both the water absorption rate and the water absorption amount under pressure, and the crosslinking reaction is carried out at a relatively low temperature. From the standpoint that it can be carried out in, and is economical, polyvalent glycidyl, polyvalent amine and silane coupling agent is preferable, more preferably polyvalent glycidyl and silane coupling agent, particularly preferably polyvalent glycidyl. .

When the surface cross-linking treatment is carried out, the amount (% by weight) of the surface cross-linking agent can be variously changed depending on the kind of the surface cross-linking agent, the conditions for cross-linking, the target performance, etc., but is not particularly limited. From the viewpoint of water absorption performance, it is preferably 0.001 to 3, more preferably 0.005 to 2, and particularly preferably 0.01 to 1, based on the weight of the surface-crosslinked prepolymer (A ′). That is, in this case, the amount (% by weight) of the surface-crosslinking agent is preferably 0.001 or more, more preferably 0.005 or more, and particularly preferably 0, based on the weight of the surface-crosslinking prepolymer (A ′). 0.01 or more, preferably 3 or less, more preferably 2 or less,
It is particularly preferably 1 or less.

The surface cross-linking treatment is carried out before drying the water-containing resin (WA) containing the polymer (A ') before surface cross-linking and water,
It may be performed at any stage during the drying of (WA) and after the drying of (WA), but from the viewpoint of easy adjustment of the crosslinking conditions for the target performance, during the drying of (WA) or ( The post-drying stage of WA) is preferred. The surface cross-linking treatment may be carried out before the surface cross-linking polymer (A ′) is treated with the surface modifier (B), simultaneously with the treatment with (B) or after the treatment with (B). May be performed at any stage.

As a method for carrying out this surface cross-linking treatment, a conventionally known method can be applied. For example, a mixed solution of a surface cross-linking agent, water and an organic solvent is added to the pre-surface-crosslinking polymer (A ').
Alternatively, a method of mixing with a water-containing resin (WA) and reacting with heating may be mentioned. The amount (% by weight) of water used during the surface cross-linking treatment is the surface cross-linking agent before the surface cross-linking polymer (A ′).
From the viewpoint of moderate penetration into the interior, it is preferably from 1 to 10, more preferably from 1 to 8, and particularly preferably from 2 to 7, based on the weight of the surface-crosslinked prepolymer (A ′). That is, the amount of water (% by weight) used in the surface cross-linking treatment is based on the weight of the pre-surface cross-linking polymer (A ′),
It is preferably 1 or more, particularly preferably 2 or more, and preferably 10 or less, more preferably 8 or less, and particularly preferably 7 or less.

As the type of organic solvent used in the surface cross-linking treatment, conventionally known hydrophilic solvents can be used, and the degree of penetration of the surface cross-linking agent into the pre-surface-crosslinking polymer (A ′), A hydrophilic organic solvent which can be appropriately selected in consideration of the reactivity of the surface cross-linking agent and is soluble in water, such as methanol or diethylene glycol, is preferable. Such solvents may be used alone or in combination of two or more. The amount of the organic solvent used (% by weight) can be variously changed depending on the kind of the solvent, but it is preferably 1 to 20 and more preferably 1 to 15 based on the weight of the surface-crosslinking prepolymer (A ′). , Particularly preferably 1 to 10.

The ratio of the solvent to water can be arbitrarily changed, and the amount of solvent used (% by weight) is preferably 20 to 80, more preferably 25 to 75, based on the weight of water. It is particularly preferably 30 to 70.
That is, the amount (% by weight) of the solvent used is preferably 20 or more, more preferably 25 or more, particularly preferably 30 or more, and preferably 80 or less, more preferably 75 or less, based on the weight of water. And particularly preferably 70 or less. The reaction temperature (° C) of the surface cross-linking treatment is 8
0 to 200 is preferable, and 90 to 18 is more preferable.
0, particularly preferably 100 to 160. That is,
The reaction temperature (° C.) of the surface cross-linking treatment is preferably 80 or higher, more preferably 90 or higher, particularly preferably 100.
It is above, and preferably 200 or less, more preferably 180 or less, and particularly preferably 160 or less. The reaction time (minutes) of the surface crosslinking treatment can be changed depending on the reaction temperature, but is preferably 3 to 60, more preferably 4 to 50, and particularly preferably 5 to 40. That is, the reaction time (minute) of the surface cross-linking treatment is preferably 3 or more, more preferably 4 or more, particularly preferably 5 or more, and preferably 60 or less, more preferably 5 or more.
It is 0 or less, particularly preferably 40 or less. A surface-crosslinking polymer (A) obtained by surface-crosslinking with a surface-crosslinking agent or a water-containing resin comprising the same and water is used for the surface-crosslinking agent of the same kind or a different surface-crosslinking agent of the same type, and additional surface-crosslinking agent. Can also be applied.

The crosslinked polymer (A) thus obtained
Particles of the crosslinked polymer (A) are obtained by drying the hydrated gel-like resin (1) and further pulverizing it as necessary to adjust the particle size. As a method for drying, a usual method can be applied, for example, 80 to
Method of drying with hot air at a temperature of 230 ° C., 100 to 230
Examples thereof include a thin film drying method using a drum dryer heated to ° C, a (heating) vacuum drying method, a freeze drying method, and an infrared drying method. The crushing method is also not particularly limited, and examples thereof include a hammer type crusher, an impact type crusher, a roll type crusher, and a method using a Schette air flow type crusher. The shape of the cross-linked polymer (A) after pulverization is not particularly limited, and irregular crushed shapes, flaky shapes, pearl shapes, rice granules, granulated granules, tufts, grape bunches and aggregates thereof, etc. Can be mentioned. The dried and / or crushed crosslinked polymer is sieved to adjust the particle size, if necessary.

The size of the crosslinked polymer (A) is not particularly limited, but 90% by weight or more (preferably 93% by weight or more, more preferably 95% by weight) of the total weight of the crosslinked polymer (A).
The particle diameter of (above) is preferably 37 to 1000 μm, more preferably 53 to 840 μm, and particularly preferably 105 to 840 μm. That is, the particle diameter (μm) of the crosslinked polymer (A) is preferably 37 or more, more preferably 53 or more, particularly preferably 105 or more, and preferably 1000 or less, more preferably 8 or more.
It is 40 or less. The weight average particle diameter (μm) of the crosslinked polymer (A) is preferably 200 to 700, particularly preferably 250 to 600, and most preferably 260 to 399. That is, the weight average particle diameter of the crosslinked polymer (A) (μ
m) is preferably 200 or more, particularly preferably 250.
As described above, it is preferably 260 or more, 700 or less, particularly preferably 600 or less, and most preferably 399 or less.

The particle size described here was measured by using a low tap test sieve shaker and a JIS standard sieve defined in JIS Z8801-1976, Perry's Chemical Engineers Handbook, 6th edition (McGlow-Hill.
Book Company, 1984, page 21). The weight average particle diameter of the crosslinked polymer (A) is, for example, 840 μm from the top of a JIS standard sieve, 71
0 μm, 500 μm, 420 μm, 350 μm, 250
.mu.m and 149 .mu.m, and a saucer in this order. Approximately 50 g of (A) particles on the uppermost 840 μm sieve
, And let it soak for 5 minutes with a low tap test sieve shaker. Weigh the resin particles on each sieve and pan,
The weight fraction is calculated with the total as 100%, and the 50% by weight particle diameter on a weight basis is taken as the weight average particle diameter.

Absorption capacity (g / g) of the crosslinked polymer (A) with respect to physiological saline (0.9 wt% sodium chloride aqueous solution)
g) (by the following measuring method) is preferably 30 or more, more preferably 35 to 80, and particularly preferably 40.
~ 70. That is, the absorption capacity (g / g) of the crosslinked polymer (A) with respect to physiological saline is preferably 30 or more, more preferably 35 or more, particularly preferably 40 or more, and further preferably 80 or less, particularly preferably Is 70 or less.

<Measurement Method of Absorption Capacity> A tea bag (length 20 cm, width 10 cm) made of a non-woven fabric is provided with JIS.
1.00 g of a sample adjusted to have a particle size of 840 to 149 μm with a standard sieve is weighed and put in 500 ml of physiological saline (0.9 wt% sodium chloride aqueous solution) for 60 minutes. Then, the tea bag is taken out from the physiological saline, suspended for 15 minutes to drain water, and then the weight (X) is measured, and the absorption capacity (g / g) is calculated from the following formula.

[Equation 1]

Under pressure against saline (20 g / cm
Absorption capacity (g / g) of the crosslinked polymer (A) in ² )
(By the following measuring method) is preferably 15 or more, more preferably 20 to 60, and particularly preferably 25 to 6.
0, most preferably 30 to 45. That is, the water absorption capacity (g / g) of the crosslinked polymer (A) under pressure against physiological saline is preferably 15 or more, more preferably 20 or more, particularly preferably 25 or more, most preferably 30 or more, Further, it is more preferably 60 or less, particularly preferably 60 or less, and most preferably 45 or less.

<Measurement method of absorption capacity under pressure> Cylindrical plastic tube (inner diameter: 30) with a nylon net having an opening of 63 μm (JIS8801-1976) attached on the bottom surface.
mm, height 60 mm), weigh 0.10 g of the sample, arrange the plastic tube vertically and arrange it on the nylon net so that the sample has a substantially uniform thickness.
The outer diameter is 29.5 mm x 22 m so that the load is / cm ^2.
Place an m-thick weight. Next, a petri dish (diameter: 12) containing 60 ml of physiological saline (saline concentration: 0.9% by weight).
cm), a plastic tube containing the sample and the weight is immersed vertically with the nylon net side facing downward, and left to stand. After 60 minutes, the sample and the plastic tube containing the weight are weighed, and the weight of the sample that absorbs physiological saline and increases is calculated. The 10-fold value of the increased weight after 10 minutes was the initial absorption capacity (g / g) under pressure for physiological saline, and the 10-fold value of the increased amount after immersion for 60 minutes was the absorption capacity under pressure for physiological saline ( g / g).

The surface modifier (B) is in a state of being attached (physically adsorbed) or fixed (chemically bonded) to the surface of the crosslinked polymer (A), thereby modifying the surface of (A), A) between particles made of a water-containing gel-like resin that absorbs water to form,
It can be used without limitation as long as it can impart water permeability. Here, the surface modifier (B) modifies the surface state of the crosslinked polymer (A) to improve the dryness performance while maintaining the absorption performance under pressure, whereas the surface crosslinking agent is , The surface of the crosslinked polymer (A) is crosslinked to improve the absorption performance under pressure. Further, the surface tension of the surface modifier (B) is 10 to 30 dyne / cm, whereas the surface tension of the surface cross-linking agent is 40 to 200 dyne / c.
It is clearly different in that it is m.

The surface modifier (B) preferably has a bonding group capable of chemically bonding with the crosslinked polymer (A), and examples of bonding modes include hydrogen bond, ionic bond and covalent bond. In addition, (B) may have not only one type of bonding group but also two or more types of bonding group. (A)
When it has a bonding group capable of chemically bonding with (B), (B) can be stably present on the surface of (A), so that the effect of permeation between particles made of a water-containing gel-like resin is likely to be sustained.

As the bonding group bonded by a hydrogen bond, a hydroxyl group (--OH), a group consisting of an ether bond (--O--), a carboxyl (salt) group (--CO ₂ M), a group consisting of a carboxylic acid anhydride ( -CO ₂ -CO-), sulfo (salt) group (-
SO ₃ M), a group consisting of a sulfuric acid ester (salt) (-OSO ₃
M) and a phosphono (salt) group (—PO (OM) ₂ ) and the like. In addition, M represents a hydrogen atom, an alkali metal, an alkaline earth metal, or ammonium. The oxygen atom in these bonding groups hydrogen-bonds with the hydrogen atom in the carboxyl group in the crosslinked polymer (A). Furthermore, when the bonding group is a hydroxyl group, a carboxyl group, a sulfo group, a group consisting of a sulfuric ester, or a phosphono group, the hydrogen atom in the bonding group is the oxygen atom and hydrogen in the carboxyl group in the crosslinked polymer (A). Join.

As the bonding group bonded by an ionic bond, an amino group (-NH ₂ ), an alkylamino group (-NHR),
Dialkylamino group (-NR _2), consisting of an amide bond group (-CONH _2, -CONHR or -CONR ₂₎ and an imide bond group (-CONHCO- or -CO-
NR-CO-) and the like. In addition, R in parentheses represents a C1-C30 (preferably 1-20, more preferably 1-18) alkyl group, an alkenyl group, an aryl group, an alkenyl group, or the like. The nitrogen atom in these bonding groups forms a salt with the carboxyl group in the crosslinked polymer (A) to form an ionic bond.

The linking group bonded by a covalent bond is a carboxyl (salt) group (-COOM) in the crosslinked polymer (A).
A functional group or the like that can chemically react with and bond with is used. For example, epoxy group (addition reaction with carboxyl group to form ester bond), hydroxyl group (esterification reaction with carboxyl group to form ester bond), amino group (amidation reaction with carboxyl group to form amide bond) And an isocyanate group (which reacts with a carboxyl group to form an amide bond via a mixed acid anhydride). Among these bonding groups, from the viewpoint of easiness of reaction, a bonding group bonded by a hydrogen bond and a bonding group bonded by an ionic bond are preferable, and more preferably a hydroxyl group, a group consisting of an ether bond, an amino group, an alkylamino group. , A dialkylamino group, a carboxyl (salt) group, a sulfo (salt) group, a sulfate ester (salt) group and a phosphono (salt) group, particularly preferably a hydroxyl group, an ether bond group, an amino group, a carboxyl (salt) A group consisting of a group, a sulfo (salt) group, a sulfate ester (salt) and a phosphono (salt) group.

The number of bonding groups in the surface modifier (B) is 1 to
20 is preferable, 5 to 18 is more preferable, 7 to 16 is particularly preferable, and 10 to 15 is most preferable. When the number of bonding groups is within this range, (B) tends to exist more stably and uniformly on the surface of the crosslinked polymer (A).

The surface tension (25 ° C., dyne / cm) of the surface modifier (B) is preferably 10 to 30, more preferably 11 to 28, particularly preferably 13 to 27, and most preferably 15 to 26. is there. That is, the surface modifier (B)
The surface tension (dyne / cm) of is preferably 10 or more,
More preferably 11 or more, particularly preferably 13 or more,
It is most preferably 15 or more, preferably 30 or less, more preferably 28 or less, particularly preferably 27 or less, and most preferably 26 or less. When the surface tension is within this range, the permeability between the particles of the water-containing gel-like resin is further improved, and when applied to the absorbent article, the dryness of the absorbent article tends to be further improved. The surface tension is determined by the ring method (C. Hub, S. G. Mason, Col.
Loid & polymer Science, Volume 253 (1974), page 566) (measurement temperature 25 ° C.).

As the surface modifier (B), for example, an organic compound (B1) having a hydrocarbon group which may contain a fluorine atom and a silicone compound (B2) can be used. The hydrocarbon group which may contain a fluorine atom has 3 to 20,000 carbon atoms (preferably 8 to 15.0).
00, more preferably 12 to 10,000 hydrocarbon groups and 3 to 60 fluorine atoms (preferably 10 to 5).
0, more preferably 15-40) and 1-30 carbon atoms
(Preferably 5 to 25, more preferably 8 to 20) and the like are used.

As the hydrocarbon group, an aliphatic hydrocarbon group and an aromatic hydrocarbon group can be used. The aliphatic hydrocarbon has 3 to 20,000 carbon atoms (preferably 8 to 1 carbon atoms).
5,000, more preferably 12 to 10,000, alkyl group and 3 to 20,000 carbon atoms (preferably 8 to 10).
15,000, more preferably 12-10,000)
Alkylene group having 3 to 20,000 carbon atoms (preferably 8 to 15,000, more preferably 12 to 10,000)
0) alkenyl group having 3 to 20,000 carbon atoms (preferably 8 to 15,000, more preferably 12 to 10,
000) alkenylene group and the like are used.

The aromatic hydrocarbon group has 6 to 2 carbon atoms.
50,000 (preferably 8 to 15,000, more preferably 10 to 10,000) aryl groups, and 6 to 30,000 carbon atoms (preferably 8 to 15,000, more preferably 10 to 10,000). ) The arylene group and the like are used.

Examples of the alkyl group include propyl group, butyl group, pentyl group, hexyl group, octyl group,
Dodecyl group, stearyl group, eicosyl group, triacontyl group and polyethylene (carbon number 4 to 20,000, preferably 8 to 15,000, more preferably 12 to 1)
10,000) or polypropylene (6 to 20,000 carbon atoms)
0, preferably 9 to 15,000, more preferably 1
2-10,000) and a hydrocarbon group obtained by removing one hydrogen atom. Examples of the alkylene group include a propylene group, a butylene group, a hexylene group, an octylene group, a dodecylene group, an octadecylene group, an eicosylene group and a polyethylene (having 4 to 20,000 carbon atoms, preferably 8 to 15,000 carbon atoms, more preferably 12 carbon atoms). -10,0
00) or polypropylene (having 6 to 20,000 carbon atoms, preferably 9 to 15,000, more preferably 12 to 1)
And a hydrocarbon group obtained by removing two hydrogen atoms from (0000).

Examples of the alkenyl group include a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, an octenyl group, a dodecenyl group, an octadecenyl group, an eicosenyl group, a triacontenyl group and a thermal degradation product of polyethylene (having 4 to 4 carbon atoms). 20,000, preferably 8 to 15,000
0, more preferably 12 to 10,000) or a thermal degradation product of polypropylene (having 6 to 20,000 carbon atoms, preferably 9 to 15,000, more preferably 12 to 10,000).
And a hydrocarbon group obtained by removing one hydrogen atom from 0). Examples of the alkenylene group include, for example, a propenylene group, a butenylene group, a hexenylene group, an octenylene group,
Dodecenylene group, octadecenylene group, eicosenylene group, triacontenylene group and thermal degradation product of polyethylene (carbon number 4 to 20,000, preferably 8 to 15,000).
0, more preferably 12 to 10,000) or a thermal degradation product of polypropylene (having 6 to 20,000 carbon atoms, preferably 9 to 15,000, more preferably 12 to 10,000).
Hydrocarbon groups obtained by removing two hydrogen atoms from 0) are mentioned.

Examples of the aryl group include phenyl group, benzyl group, ethylphenyl group, tetradecylphenyl group, nonylphenyl group, dimethylphenyl group, diethylphenyl group, diheptylphenyl group, dinonylphenyl group and dinonylphenyl group. Examples thereof include a phenyl group, a tolyl group, a mesityl group, a cumenyl group, a tolyl group, a xylyl group, a naphthyl group, an anthryl group and a phenanthryl group. Examples of the arylene group include phenylene group, ethylphenylene group, tetradecylphenylene group, nonylphenylene group, dimethylphenylene group, diethylphenylene group, diheptylphenylene group, dinonylphenylene group, dinonylphenylphenylene group, tolylene group, Mesitylene group, cumenylene group, tolylene group, xylylene group,
Naphthylene group, anthrylene group, phenanthrylene group and bisphenol (bisphenol, bisphenol A
And bisphenol F, etc.) and the like, residues excluding phenolic hydroxyl groups.

Of these, aliphatic hydrocarbon groups are preferred from the viewpoint of lower surface tension, more preferably alkyl groups, alkylene groups, alkenyl groups and alkenylene groups, and particularly preferably pentyl groups, hexyl groups, octyl groups. , Dodecyl group, stearyl group, triacontyl group, octylene group, dodecylene group, hydrocarbon group obtained by removing 2 hydrogen atoms from polyethylene or polypropylene, 2 hydrogen atoms from polyethylene thermal degradation product or polypropylene thermal degradation product Hydrocarbon groups removed, particularly preferably octyl group, dodecyl group, stearyl group, triacontyl group, dodecylene group, hydrocarbon groups obtained by removing two hydrogen atoms from polyethylene or polypropylene, thermal degradation products of polyethylene and heat of polypropylene. Hydrocarbonized water with two hydrogen atoms removed from the degraded product Group, most preferably dodecyl group, stearyl group, triacontyl group, polyethylene two hydrogen atoms from or polypropylene except hydrocarbon group,
It is a hydrocarbon group obtained by removing two hydrogen atoms from a thermal degradation product of polyethylene or a thermal degradation product of polypropylene.

As the fluorine-containing hydrocarbon group, a fluorine-containing aliphatic hydrocarbon group and a fluorine-containing aromatic hydrocarbon group can be used. As the fluorine-containing aliphatic hydrocarbon group,
Perfluoroalkyl group (having 1 to 30 carbon atoms, preferably 5 to 25, more preferably 8 to 20), perfluoroalkyl (having 1 to 30 carbon atoms, preferably 5 to 25, more preferably 8 to 20) -alkylene Group (1 to 2 carbon atoms
0, preferably 1-10, more preferably 2-8),
A perfluoroalkylene group (having 1 to 30 carbon atoms, preferably 5 to 25, more preferably 8 to 20), a perfluoroalkenyl group (having 3 to 30 carbon atoms), a perfluoroalkenylene group (having 3 to 30 carbon atoms) and the like. Used. As the fluorine-containing aromatic hydrocarbon group, a perfluoroaryl group (having 6 to 30 carbon atoms), a perfluoroarylene group (having 6 to 30 carbon atoms) and the like are used.

Examples of the perfluoroalkyl group include a trifluoromethyl group, a pentafluoroethyl group,
Pentafluoropropyl group (pentafluoroethylmethyl group, etc.), heptafluoropropyl group, heptafluorobutyl group (heptafluoromethyl group, etc.), nonafluorohexyl group (nonafluorobutylethyl group, etc.), tridecafluorooctyl group (tri Decafluorohexylethyl group, etc.) and a heptadecafluorododecyl group (heptadecafluorooctylbutyl group, etc.) and the like. Examples of the perfluoroalkylalkylene group include a pentafluoroethyl-ethylene group, a heptafluoropropyl-ethylene group, a nonafluorobutyl-ethylene group, a tridecafluorohexyl-ethylene group, and a heptadecafluorooctyl-ethylene group. .

Examples of the perfluoroalkylene group include difluoromethylene group, tetrafluoroethylene group, hexafluoropropylene group, octafluorobutylene group, dodecafluorohexylene group, hexadecafluorooctylene group and tetracosafluorododecylene group. Groups and the like. As a perfluoroalkenyl group,
Examples thereof include a pentafluoropropenyl group, a heptafluorobutenyl group, a nonafluoropentenyl group, an undecafluorohexenyl group, a pentadecaoctenyl group, a tricosadodecenyl group, and a nonapentacontafluorotriacontenyl group. . Examples of the perfluoroalkenylene group include a tetrafluoropropenylene group, a hexafluorobutenylene group, a decafluorohexenylene group, a tetradecafluorooctenylene group, a docosafluorododecenylene group, and an octapentacontafluorotricontenylene group. Groups and the like.

Examples of the perfluoroaryl group include a pentafluorophenyl group, a heptafluoromethylphenyl group, a nonafluoroethylphenyl group, a tritriacontafluorotetradecylphenyl group, a nonafluorodimethylphenyl group, and a tridecafluorodiethylphenyl group. And tritriacontafluorodiheptylphenyl group and the like. Examples of the perfluoroarylene group include a tetrafluorophenylene group, hexafluoromethylphenylene group, octafluoroethylphenylene group, ditriacontafluorotetradecylphenylene group, octafluorodimethylphenylene group, dodecafluorodiethylphenylene group and ditriacontaene group. A fluorodiheptyl phenylene group etc. are mentioned.

Of these, from the viewpoint of surface tension, those having 2 or more carbon atoms are preferable, those having 3 or more carbon atoms are more preferable, and fluorine-containing aliphatic hydrocarbon group (pentafluoropropyl group, hepta) is particularly preferable. Fluoropropyl group, heptafluorobutyl group, nonafluorohexyl group, tridecafluorooctyl group, heptadecafluorododecyl group, nonafluorobutyl-ethylene group, tridecafluorohexyl-ethylene group, heptadecafluorooctyl-ethylene group, tetra Fluoroethylene group,
Hexafluoropropylene group, octafluorobutylene group, dodecafluorohexylene group, hexadecafluorooctylene group, tetracosafluorododecylene group, nonafluoropentenyl group, undecafluorohexenyl group, pentadecaoctenyl group, tricosad Decenyl group,
Nonapentacontafluorotriacontenyl group, hexafluorobutenylene group, decafluorohexenylene group,
Tetradecafluorooctenylene group, docosafluorododecenylene group and octapentacontafluorotricontenylene group) and fluorine-containing aromatic hydrocarbon group (heptafluoromethylphenyl group, nonafluoroethylphenyl group, tritriacontafluorotetra) Decylphenyl group, nonafluorodimethylphenyl group, tridecafluorodiethylphenyl group, tritriacontafluorodiheptylphenyl group, hexafluoromethylphenylene group, octafluoroethylphenylene group, ditriacontafluorotetradecylphenylene group, octafluorodimethyl A phenylene group, a dodecafluorodiethylphenylene group and a ditriacontafluorodiheptylphenylene group).

Among the organic compounds (B1) having a hydrocarbon group which may contain a fluorine atom, those not containing a fluorine atom are, for example, those having a hydroxyl group as a bonding group, for example, octyl. alcohol,
Examples include octylene diol, triacontyl alcohol, octenyl alcohol, triacontenyl alcohol and octenylene diol. Moreover, as a thing which has a group which consists of an ether bond as a coupling group, for example, octyl alcohol ethylene oxide (1-20
Adduct, octylenediol ethylene oxide (1 to 20) adduct, triacontyl alcohol ethylene oxide (1 to 20) adduct, octenyl alcohol ethylene oxide (1 to 20) adduct, triaconte Nyl alcohol ethylene oxide (1-20
Individual) adduct and octenylene diol ethylene oxide (1 to 20) adduct.

Examples of those having a carboxyl group as a bonding group include octanecarboxylic acid, octanedicarboxylic acid and triacontanecarboxylic acid. Moreover, as a thing which has a group which consists of carboxylic acid anhydride as a coupling group, for example, polyethylene-maleic acid modified | denatured product (weight average molecular weight by gel permeation chromatography (abbreviated as Mw hereafter) is 500-3.
50,000, preferably 600 to 15,000, more preferably 800 to 10,000, that is, 500 or more, preferably 600 or more, more preferably 800 or more, and 30,000 or less, preferably 15,000 or less, More preferably 10,000 or less) and a polypropylene-maleic acid modified product (Mw 500 to 30,000).
0, preferably 600 to 15,000, more preferably 800 to 10,000, that is, 500 or more, preferably 600 or more, more preferably 800 or more, and 30,000 or less, preferably 15,000 or less, more preferably Is 10,000 or less) and the like. In addition, examples of those having a sulfo group or a phosphono group as a bonding group include octylsulfonic acid and triacontylphosphonic acid. In addition, examples having an amino group as a bonding group include octylamine, dioctylamine, triacontylamine, triacontylmethylamine, and octylenediamine.

Further, as a group having an amide bond as a bonding group, for example, a modified product of polyethylene-maleic acid amide (Mw 500 to 30,000, preferably 600 to 15,000, more preferably 800 to 1)
10,000, ie 500 or more, preferably 600
Or more, more preferably 800 or more, or 30,000
Or less, preferably 15,000 or less, more preferably 10,000 or less) and a polypropylene-maleic acid amide modified product (Mw 500 to 30,000, preferably 6).
00-15000, more preferably 800-10,0
00, that is, 500 or more, preferably 600 or more,
More preferably 800 or more and 30,000 or less,
Preferably 15,000 or less, more preferably 10.0
00 or less) and the like. In addition, a polyethylene-maleic acid imide-modified product (Mw 500 to 30,000, preferably 600 to 15,000, more preferably 80) as a group having an imide bond as a bonding group.
0 to 10,000, that is, 500 or more, preferably 600 or more, more preferably 800 or more, and 30,
000 or less, preferably 15,000 or less, more preferably 10,000 or less) and a polypropylene-maleic acid imide modified product (Mw 500 to 30,000, preferably 600 to 15,000, more preferably 800 to
10,000, ie 500 or more, preferably 60
0 or more, more preferably 800 or more, and 30,000
0 or less, preferably 15,000 or less, and more preferably 10,000 or less). Further, examples having an epoxy group as a bonding group include octyl glycidyl ether, octylene diglycidyl ether, and triacontyl glycidyl ether.

Among the organic compounds (B1) having a hydrocarbon group which may contain a fluorine atom, those containing a fluorine atom include those having a hydroxyl group as a bonding group, for example, nonafluorohexyl alcohol. ,
Dodecafluorohexylene diol, tetracosafluoro dodecylene diol, decafluorohexenyl alcohol, tetrafluorophenol, tetrafluorofusihydroxybenzene, tri (triacontafluoroheptyl) phenol and tri (triacontafluoroheptyl) dihydroxybenzene To be

As a group having an ether bond as a bonding group, for example, nonafluorohexyl alcohol ethylene oxide (1 to 20) adduct,
Dodecafluorohexylene diol ethylene oxide (1 to 20) adduct, tetracosafluoro dodecylene diol ethylene oxide (1 to 20) adduct, decafluorohexenyl alcohol ethylene oxide (1 to 20) adduct, tetra Fluorophenol ethylene oxide (1 to 20) adduct, tetrafluoro fujihydroxybenzene ethylene oxide (1 to 20)
Individual) adduct, tri (triacontafluoroheptyl) phenol ethylene oxide (1 to 20) adduct and tri (triacontafluoroheptyl) dihydroxybenzene ethylene oxide (1 to 20) adduct, and the like.

Examples of those having a carboxyl group as a bonding group include nonafluorohexanecarboxylic acid and dodecafluorohexanedicarboxylic acid. In addition, examples having a sulfo group or a phosphono group as a bonding group include nonafluorohexyl sulfonic acid and nonafluorohexyl phosphonic acid. In addition, examples of those having a group consisting of a carboxylate as a bonding group include nonafluorohexanecarboxylic acid sodium salt and dodecafluorohexanedicarboxylic acid disodium salt.

Examples of compounds having an amino group as a bonding group include nonafluorohexylamine, di (nonafluorohexyl) amine, dodecafluorohexylenediamine, tetracosafluorododecylenediamine and decafluorohexenylamine. Can be mentioned. In addition, examples having an epoxy group as a bonding group include nonafluorohexyl glycidyl ether and dodecafluorohexylene glycidyl ether.

Among these (B), from the viewpoint of surface tension and easiness of bond formation, a bonding group (hydroxyl group, group consisting of ether bond, carboxyl (salt)) bonded by hydrogen bond.
Group, a group consisting of a carboxylic acid anhydride, a sulfo (salt) group, a group consisting of a sulfuric acid ester (salt) and a phosphono (salt) group, and a bonding group (amino group, alkylamino group, dialkylamino group) which is bonded by an ionic bond. , A group consisting of an amide bond and a group consisting of an imide bond), and more preferably triacontyl alcohol, triacontenyl alcohol, triacontyl alcohol ethylene oxide (1 to 20) adduct, triacontenyl. Alcohol ethylene oxide (1 to 20) adduct, triacontylcarboxylic acid, polyethylene-maleic acid modified product, polypropylene-maleic acid modified product, triacontylphosphonoic acid, dioctylamine, triacontylamine, triacontylmethyl Amine, polyethylene-maleic acid amide Objects, polypropylene - maleic acid amide-modified products, polyethylene - maleimide-modified products,
Polypropylene-maleic acid imide modified product, nonafluorohexyl alcohol, dodecafluorohexylene diol, tetracosafluoro dodecylene diol, decafluorohexenyl alcohol, tetrafluorophenol, tetrafluorofudihydroxybenzene, tritriacontafluoroheptylphenol, tri Triacontafluoroheptyldihydroxybenzene, nonafluorohexyl alcohol ethylene oxide (1-20
Adduct, dodecafluorohexylenediol ethylene oxide (1 to 20) adduct, tetracosafluorododecylene diol ethylene oxide (1 to 20)
Adducts, decafluorohexenyl alcohol ethylene oxide (1 to 20) adducts, tetrafluorophenol ethylene oxide (1 to 20) adducts, tetrafluorofusihydroxybenzene ethylene oxide (1 to 20) adducts, tritoria Contafluoroheptylphenol ethylene oxide (1 to 20) adduct, tritriacontafluoroheptyldihydroxybenzene ethylene oxide (1 to 20) adduct, nonafluorohexylcarboxylic acid, dodecafluorohexylenecarboxylic acid, nonafluorohexylsulfone Acid, nonafluorohexylphosphonic acid, sodium nonafluorohexylcarboxylate, sodium dodecafluorohexylene dicarboxylate, nonafluorohexylamine, dinonafluorohexyla Down a dodecafluoro hexane diamine, tetracosanol fluoro-dodecylcarbamoyl diamine and decafluoro hexenyl amine.

As the silicone compound (B2), a modified silicone having a bonding group is used. The modified silicone is a silicone oil in which various organic groups are introduced into a part of the methyl groups of dimethylsiloxane to impart chemical reactivity, etc., and the structure has a side chain introduction type (side chain of polysiloxane depending on the introduction position of the organic group). With an organic group introduced in),
Both ends introduced type (organic groups introduced at both ends of polysiloxane), one end introduced type (organic groups introduced at one end of polysiloxane), side chain both ends type (side chain of polysiloxane and (Introducing an organic group at both ends)). Of these, any type may be used.

As the silicone compound (B2), polyether-modified silicone oil (polyethylene oxide-modified silicone and polyethylene oxide / polypropylene oxide-modified silicone, for example, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-351 <surface tension 22. 0
Dyne / cm, viscosity 100 cSt>, KF-352 <surface tension 23.1 dyne / cm, viscosity 1600 cSt>,
KF-353 <20.2 dynes / cm, viscosity 400 cS
t>, KF-615A, manufactured by Toray Dow Corning Silicone Co., Ltd., trade name: BY-16-004, SH3746.
<Surface tension 19.8 dynes / cm, viscosity 120 cSt
>, SF8410 <surface tension 24.8 dynes / cm, viscosity 2900 cSt>), carboxyl-modified silicone oil (for example, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: X-22-
162C <surface tension 20.1 dynes / cm, viscosity 207
cSt>, X-22-3701E <surface tension 25.3 dyne / cm, viscosity 3000 cSt>, X-22-371.
0 <surface tension 19.7 dynes / cSt, viscosity 50 cSt
>, Manufactured by Toray Dow Corning Silicone Co., Ltd., product name:
BY-16-750 <surface tension 20.0 dynes / cm,
Viscosity 125 cSt>, SF8418 <surface tension 25.0
Dyne / cm, viscosity 2500 cSt>), alkyl-modified silicone oil (eg, Shin-Etsu Chemical Co., Ltd., trade name: KF-412, KF-413 <surface tension 20.1 dyne / cm, viscosity 100 cSt>, KF-414 < Surface tension of 19.3 dyne / cm, viscosity of 100 cSt>, manufactured by Toray Dow Corning Silicone, trade name: SH20
3 <surface tension 22.0 dynes / cm, viscosity 1200 cS
t>, SH230 <surface tension 21.8 dyne / cm, viscosity 1400 cSt>, SF8416 <surface tension 21.0.
Dyne / cm, viscosity 900 cSt>), epoxy-modified silicone oil (for example, manufactured by Shin-Etsu Chemical Co., Ltd., trade name:
KF-105 <surface tension 22.2 dynes / cm, viscosity 1
5cSt>, X-22-163A <surface tension 21.6 dynes / cm, viscosity 30cSt>, X-22-163C <
Surface tension 20.0 dyne / cm, viscosity 103 cSt>,
KF-1001 <surface tension 27.5 dynes / cm, viscosity 19000 cSt>, X-22-169B <surface tension 1
9.0 dynes / cm, viscosity 56 cSt>, manufactured by Toray Dow Corning Silicone, trade name: BY16-855
D <surface tension 22.1 dynes / cm, viscosity 10 cSt
>, SF8411 <surface tension 26.1 dynes / cm, viscosity 8000 cSt>, BY16-839 <surface tension 2
5.9 dynes / cm, viscosity 6000 cSt>, SF84
21 <surface tension 23.1 dynes / cm, viscosity 3500c
St>), amino-modified silicone oil (for example, Shin-Etsu Chemical Co., Ltd., trade name: KF-880 <surface tension 21.
3 dynes / cm, viscosity 650 cSt>, KF-859 <
Surface tension 20.4 dyne / cm, viscosity 60 cSt>, K
F-867 <Surface tension 22.1 dynes / cm, viscosity 13
00cSt>, KF-8003 <surface tension 22.0 dynes / cm, viscosity 1850 cSt>, KF-8004 <surface tension 21.4 dies / cm, viscosity 800 cSt>, manufactured by Toray Dow Corning Silicone, trade name: BY -1
6-853C <surface tension 21.5 dyne / cm, viscosity 1
0cSt>, BY16-208 <surface tension 25.3 dyne / cm, viscosity 3000 cSt>, BY16-209 <
Surface tension 21.0 dyne / cm, viscosity 500 cSt>,
BY16-850 <surface tension 22.1 dynes / cm, viscosity 1100 cSt>, BY16-872 <surface tension 2
8.5 dynes / cm, viscosity 20000 cSt>) and alkoxy-modified silicone oil (eg, Shin-Etsu Chemical Co., Ltd., trade names: KF-857, KF-862, KF-8).
001) and the like. Of these, polyether-modified silicone oil is preferable, and polyethylene oxide-modified silicone is more preferable, because it is available at a relatively low cost. The surface tension and the viscosity are the values measured at 25 ° C.

The viscosity (cSt) of the surface modifier (B) at 25 ° C. is preferably 10 to 2,000, more preferably 20 to 1, from the viewpoint of uniform mixing with the crosslinked polymer (A). 500, particularly preferably 20 to 1000. That is, the viscosity (cSt) at 25 ° C. of the surface modifier (B) is preferably 10 or more, more preferably 20 or more, and preferably 2,000 or less, more preferably 1,500 or less, and particularly preferably Preferably 100
It is 0 or less. If it is less than this range, (B) tends to penetrate into the crosslinked polymer (A), and the desired effect tends to be difficult to be exhibited. On the other hand, if this range is exceeded,
It tends to be unfavorable in terms of uniform mixing with (A).

Two or more kinds of these surface modifiers (B) can be used in combination. The surface modifier (B) can also be used in the form of being dissolved or emulsified in water and / or a volatile solvent. As a volatile solvent, vapor pressure at 20 ° C (mmH
g) is preferably 17.5 to 700, more preferably 20 to 600, and particularly preferably 30 to 500. That is, the vapor pressure of the volatile solvent (20 ° C, m
mHg) is preferably 17.5 or more, more preferably 20 or more, particularly preferably 30 or more, and 70
It is preferably 0 or less, more preferably 600 or less, and particularly preferably 500 or less. Examples of the volatile solvent include alcohols (methanol, ethanol, isopropyl alcohol, etc.), hydrocarbons (hexane, cyclohexane, toluene, etc.), ethers (diethyl ether, tetrahydrofuran, etc.), ketones (acetone, methyl ethyl ketone, etc.), esters (acetic acid, etc.). Ethyl, isopropyl acetate, diethyl carbonate, etc.) and the like. When water and a volatile solvent are used, the amount (% by weight) of these is preferably 1 to 900, more preferably 5 to 700, and particularly preferably 10 based on the weight of (B).
~ 400. That is, in this case, the usage amount (% by weight) of water and the volatile solvent was 1 based on the weight of (B).
The above is preferable, more preferably 5 or more, particularly preferably 10 or more, and preferably 900 or less, more preferably 700 or less, and particularly preferably 400 or less.

The HLB of the surface modifier (B) is preferably 7-18, more preferably 8-18, and particularly preferably 10-18. When the HLB is within this range, the water absorption rate (particularly the initial water absorption amount under pressure) and the water absorption capacity under pressure are further improved, and particles of a water-absorbing polymer having a better moisture absorption blocking performance are easily obtained.

The amount (% by weight) of the surface modifier (B) used is
Based on the weight of the crosslinked polymer (A), it is preferably 0.001 to 3, more preferably 0.005 to 2, particularly preferably 0.07 to 1.5, and most preferably 0.1 to 1.
It is 0. That is, the amount of the surface modifier (B) used (% by weight) was 0.00 based on the weight of the crosslinked polymer (A).
1 or more, more preferably 0.005 or more,
It is particularly preferably 0.07 or more, most preferably 0.1 or more, and preferably 3 or less, more preferably 2
Or less, particularly preferably 1.5 or less, and most preferably 1.
It is 0 or less. If it is less than this range, a difference in effect is less likely to appear with the water-absorbent polymer not treated with (B). on the other hand,
If it exceeds this range, it tends to be unfavorable in terms of powder fluidity.

The water-absorbent polymer of the present invention may be composed of the cross-linked polymer (A) and the surface modifier (B).
(B) is preferably present near the surface of
It is desirable to mix and process (A) and (B) after the polymerization of. When (A) is obtained by reverse phase suspension polymerization, during the polymerization step, immediately after the polymerization step, and during the dehydration step (water content: 10% by weight).
During the process of dehydration before and after), immediately after the dehydration process, during the process of separating the water-absorbent resin obtained by the polymerization and the organic solvent used for the polymerization, immediately before the surface crosslinking treatment step, during the surface crosslinking treatment step, and the surface crosslinking treatment step. Immediately after or during the drying step (the step of drying to 10% by weight or less), there may be mentioned a method of mixing and treating (B). Among these, from the viewpoint of uniformly treating the particle surface of (A), a step of separating the water absorbent resin obtained by the polymerization and the organic solvent used for the polymerization immediately after the polymerization step, during the dehydration step, immediately after the dehydration step. It is preferable to mix / treat the intermediate group immediately before the surface cross-linking treatment step, during the surface cross-linking treatment step, immediately after the surface cross-linking treatment step, or during the drying step. From the viewpoint of easiness of binding with, more preferably immediately after the polymerization step, during the dehydration step, immediately after the dehydration step, during the step of separating the water-absorbent resin obtained by the polymerization and the organic solvent used for the polymerization, surface crosslinking treatment It is a mixing treatment immediately before the step, during the surface crosslinking treatment step or immediately after the surface crosslinking treatment step, particularly preferably during the dehydration step, immediately before the surface crosslinking treatment step, during the surface crosslinking treatment step or immediately after the surface crosslinking treatment step. by doing That.

That is, the step of mixing and treating (A) and (B) may be performed at any stage, but it is preferably performed before, during or after the removal of water from the water-containing resin (WA), From the viewpoint of easiness of bonding between the bonding group in the surface modifier (B) and the crosslinked polymer (A), it is more preferable that the water content of the water-containing resin (WA) is 10% by weight or more, that is, water. It is a stage before or during the removal.

As a method of mixing and treating the crosslinked polymer (A) and the surface modifier (B), (B) is previously added at a high concentration (for example, 5 to 20% by weight based on the particles of (A)). Add to (A) at room temperature and mix for 10 minutes or more to prepare a masterbatch. Add (B) masterbatch to (A) at room temperature so as to obtain a predetermined addition amount and mix for 10 minutes or more. -The method of treating, the method of adding or spraying (B) at room temperature while stirring (A), mixing and treating, etc. are mentioned. Mixing of crosslinked polymer (A) and surface modifier (B)
The industrial equipment for treatment is not particularly limited, but for example, conical blender, nauter mixer, double-arm kneader, V-type mixer, fluidized bed type mixer, turbulizer, screw type line blending device. Mechanical mixing devices such as a ribbon mixer and a mortar mixer are preferably used.

The surface modifier (B) has a viscosity of 1,000 to
In the case of 2,000 cSt or more, in addition to using water and / or a volatile solvent, the crosslinked polymer (A) and / or the modifier (B) is heated (30 to 200 ° C., preferably 40 to
160 ° C., more preferably 50 to 120 ° C., that is, 30 ° C. or higher, preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and 200 ° C. or lower, preferably 160
(A) and (B) can be mixed and treated after the temperature is lower than or equal to ° C, more preferably lower than or equal to 120 ° C. When the cross-linked polymer (A) is a cross-linked polymer in which the surface of the particle is surface-crosslinked with a surface cross-linking agent, (B) may be added to the surface cross-linking agent solution. When the bonding mode of the bonding group of (B) is mainly a covalent bond, it is preferable to perform a heating reaction by mixing (A) and (B) and then providing a heating step. The heating temperature (° C) is preferably 80 to 200, more preferably 90 to 160, and particularly preferably 1
It is 00-140. That is, the heating temperature (° C) is 8
It is preferably 0 or more, more preferably 90 or more, particularly preferably 100 or more, and preferably 200 or less, more preferably 160 or less, particularly preferably 14 or less.
It is 0 or less. The reaction time (minute) can be changed depending on the reaction temperature, but is preferably 3 to 60, more preferably 5 to 40, and particularly preferably 8 to 30. That is, the reaction time (minute) is preferably 3 or more, more preferably 5 or more, particularly preferably 8 or more, and preferably 60 or less, more preferably 40 or less, and particularly preferably 30 or less. The fractal order does not change before and after the addition of (B). When the bonding mode of the bonding group in (B) is mainly hydrogen bond or mainly ionic bond, (A)
After mixing (B) and (B), there is no need to provide a step of heating.

If necessary, an additive (C) can be added to the water-absorbent polymer comprising the crosslinked polymer (A) and the surface modifier (B) of the present invention. As the additive (C), a water-absorbent polymer or an ordinary additive used in absorbent articles can be used. , Fragrances, deodorants, inorganic powders and organic fibrous substances can be used. Examples of preservatives include preservatives such as salicylic acid, sorbic acid, dehydroacetic acid and methylnaphthoquinone, and bactericidal agents such as chloramine B and nitrofurazone. Examples of the fungicide include butyl p-oxybenzoate and the like, and examples of the antibacterial agent include benzalkonium chloride salt and chlorhexidine gluconate. As an antioxidant, triethylene glycol-bis- [3- (3-t-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-
Examples thereof include hindered phenol antioxidants such as 4-hydroxybenzylphosphonate-diethyl ester, amine antioxidants such as n-butylamine, triethylamine and diethylaminomethylmethacrylate, and mixtures of two or more thereof.

As the UV absorber, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2-
(3,5-di-t-butyl-2-hydroxyphenyl)
Benzotriazole, 2- (3,5-di-t-butyl-
Benzotriazole-based UV absorbers such as 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 benzophenone-based UV absorbers, 2-ethoxy-
Examples include oxalic acid anilide-based UV absorbers such as 2'-ethyloxalic acid bisanilide, and mixtures of two or more of these. Examples of the colorant include inorganic pigments such as carbon black, titanium oxide and ferrite, organic pigments such as azo lake, benzimidazolone and phthalocyanine, and dyes such as nigrosine and aniline. Examples of the fragrance include natural flavors such as musk, Avies oil and turpentine, and synthetic flavors such as menthol, citral, p-methylacetophenone and floral. Examples of the deodorant include zeolite, silica, flavonoid, cyclodextrin and the like.

As the inorganic powder, calcium carbonate, kaolin, talc, mica, bentonite, clay, sericite, asbestos, glass fiber, carbon fiber, glass powder, glass balloon, silas balloon, coal powder, metal powder, ceramic powder, Examples thereof include silica, zeolite and slate powder. The shape may be arbitrary, and the number average particle diameter determined by the light scattering method is preferably 0.1 μm to 1 mm.

Examples of the organic fibrous substances include natural fibers [cellulose (cotton, sawdust, straw, etc.) and other grass charcoal, wool, microfibrils and bacterial cellulose], artificial fibers (cellulosics such as rayon and acetate). , Synthetic fibers (polyamide, polyester, acrylic, etc.), pulp [mechanical pulp (ground wood pulp and asplund ground wood, etc.), chemical pulp (sulfurous acid pulp, soda pulp, sulfate pulp,
Nitric acid pulp and chlorine pulp, etc.), semi-chemical pulp,
Examples thereof include recycled pulp (for example, mechanically crushed or crushed paper produced by making pulp once, or recycled wastepaper pulp that is mechanically crushed or crushed waste paper).

When the additive (C) is used, the amount (% by weight) of these varies depending on the use, but the cross-linked polymer (A) is used.
0.01-20, more preferably 0.02-10, particularly preferably 0.03-
8 That is, in this case, the amount (% by weight) of the additive (C) was 0. 0, based on the weight of the crosslinked polymer (A).
01 or more, more preferably 0.02 or more,
It is particularly preferably 0.03 or more, preferably 20 or less, more preferably 10 or less, and particularly preferably 8
It is the following.

When the additive (C) is used, it can be added at any stage. Examples of the method of adding include the following. A method of previously mixing the additive (C) with the crosslinked polymer (A). A method in which the surface modifier (B) is mixed with the additive (C), and then the cross-linked polymer (A) is mixed and treated. A method of adding the additive (C) while mixing the crosslinked polymer (A) and the surface modifier (B). A method in which the cross-linked polymer (A) is treated with the surface modifier (B) and then the additive (C) is added and mixed. Among these methods, and method are preferable,
The methods of and are more preferred.

The degree of dust generation (CPM) of the water-absorbent polymer is 60.
The following is preferred, 35 or less is more preferred, 25 or less is particularly preferred, and 10 or less is most preferred. The dust generation rate of the water-absorbent polymer is an index of suspended dust contained in the resin. The relative concentration of suspended dust is displayed as an integrated value of the amount of scattered light (1 cpm when the stearic acid particles having an average particle diameter of 0.3 μm are 0.01 mg / m ³ ).

<Measurement Method of Dust Degree> A suction port of a 1-liter suction bottle and a digital dust meter (for example, MOD manufactured by Shibata Kagaku: MOD
EL P-5) inlet and inner diameter 7mm, length 10cm
Connect with a glass tube. From the upper mouth of the suction bottle, 20 g of the sample is dropped into the suction bottle using a funnel. The number of dust particles generated per minute from the dropped sample was measured using a digital dust meter, and this value was used as the dust generation rate (unit: CPM, 1 CPM).
= 0.001 mg / m ³ , the measurement range of MODEL P-5 is 0.01 to 100 mg / m ³ ).

The water-absorbent polymer of the present invention is suitable for absorbent articles and the like which require water absorption and / or water retention.
It is most suitable for sanitary items such as disposable diapers (children's paper diapers and adult paper diapers), sanitary napkins, incontinence pads, breast pads, surgical underpads and pet sheets.
In addition, freshness retention material, cold insulation material, desiccant, drip absorbent,
It is also extremely useful for various applications such as anti-condensation agents, water retention agents for plants and soil, coagulants such as sludge, water blocking and packing materials for civil engineering and construction, water blocking materials for electric cables and optical fiber cables, and artificial snow. is there.

The SDME dryness (%) of the absorbent article using the water-absorbent polymer of the present invention is preferably 80 or less,
More preferably 70 or less, particularly preferably 60 or less,
Most preferably, it is 50 or less, and from the viewpoint of cost and the like, it is preferably 5 or more, more preferably 10 or more, particularly preferably 15 or more, and most preferably 20 or more. SDME dryness is an index that quantifies the wetness of the surface of the absorbent article by the light scattering method. When the surface of the absorbent article is in the dry state, the incident light is almost totally reflected and the surface of the absorbent article is in the wet state. In this case, the principle that incident light is diffusely reflected is applied.

<SDME Dryness> A scanner of an SDME tester (for example, Systems Engineering Co., Ltd.) is placed on an absorbent article (for example, a disposable diaper) soaked in water so that the whole can be used, and a 100% dryness value is set. , Then, the detector of SDME tester 1
Place on an absorbent article (diaper) dried at 00 ° C. for 5 hours, set 0% dryness, and calibrate the SDME tester. Next, a cylinder having an inner diameter of 6.0 cm and a height of 4.0 cm is placed in the center of the absorbent article, and 80 ml of artificial urine is put into the cylinder so that the absorbent absorbs the artificial urine. Leave it for 30 minutes as it is, and add 80 ml of artificial urine again in the same manner. Two
One second after the artificial urine charged the second time was absorbed by the absorber, the scanner was set in the center of the absorber, and the light reflectance of the surface of the center of the absorbent article was measured for 5 minutes. ). The artificial urine is an aqueous solution having the following composition.

[0112] Sodium chloride 0.03% by weight Magnesium sulfate 0.08% by weight Sodium chloride 0.80% by weight Urea 2.00% by weight Ion-exchanged water 97.09% by weight

[0113]

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Unless otherwise specified, parts are parts by weight and% is% by weight.
Indicates. Moreover, the fractal order, the weight average particle diameter, the initial absorption amount under pressure, the absorption capacity under pressure, the dust generation degree, and the SDME dryness of the absorbent article prepared using the water-absorbent polymer were measured by the following methods.

<Fractal Order> Scanning electron micrographs of one sample are taken at magnifications of 20, 40, 80, 150 and 300 times. The grain contour length and grain projected area were determined for each of these photographs. Next, XY where the common logarithm of the particle contour length is the X axis and the common logarithm of the particle projected area is the Y axis
The points (5 points) obtained from each photograph were plotted on the coordinates, and the points were connected by a straight line by the least square method, and the slope of this straight line was calculated. Further, a straight line was drawn for each of the four resin particles taken out randomly, and the inclination thereof was determined. The average value of the slopes of the straight lines was calculated for these 5 particles, and this was taken as the fractal order.

<Weight average particle size> JIS standard sieve (JIS8
801-1976) from above, 840 μm, 710 μm
m, 500 μm, 420 μm, 350 μm, 250 μm
And 149 μm, and a saucer in this order. About 50 g of the particles of (A) were placed in the uppermost 840 μm sieve and allowed to permeate for 5 minutes with a low tap test sieve shaker. The weight of the resin particles on each sieve and the pan was weighed, and the total was taken as 100% to obtain the weight fraction.

<Initial Absorption Amount Under Pressurization and Absorption Ability Under Pressurization> Sample 0. 1 g is weighed, the plastic tube is made vertical, and the sample is arranged on a nylon net so that the sample has a substantially uniform thickness. The sample has an outer diameter of 29.5 mm × so that the load is 20 g / cm ^2.
Place a 22 mm weight. Saline (salt concentration 0.9
%) A plastic tube containing the sample and the weight is immersed in a petri dish (diameter: 12 cm) containing 60 ml with the nylon net side facing down and left to stand. 10 minutes later and 60
After a minute, the sample and the plastic tube containing the weight are weighed, the weight of the sample absorbed by physiological saline is calculated, and the increased weight is calculated 10 minutes after the initial absorption of physiological saline under pressure. Magnification (g / g), the 10-fold increase after 60 minutes is the absorption capacity under pressure against physiological saline (g
/ G).

<Measurement method of absorption capacity under normal pressure> Opening 6
Tea bag made of 3 μm (JIS8801-1976) nylon net (length 20 cm, width 10 cm)
1.00 g of a sample adjusted to a particle size of 840 to 149 μm with a JIS standard sieve was weighed and put into a physiological saline solution (0.
Immersion in 500 ml of 9 wt% sodium chloride aqueous solution) for 60 minutes. Then, the tea bag is taken out from the physiological saline, suspended for 15 minutes to drain water, and then the weight (X) is measured, and the absorption capacity (unit: g / g) is calculated from the following formula.

[Equation 2]

<Dust generation degree> A suction port of a 1-liter suction bottle and a suction port of a digital dust meter (MODEL P-5 manufactured by Shibata Scientific Co., Ltd.) are connected with a glass tube having an inner diameter of 7 mm and a length of 10 cm. From the mouth of the top of the suction bottle, use a funnel to sample 20g
Drop into a suction bottle. The number of dust particles generated per minute from the dropped sample was measured using a digital dust meter, and this value was used as the dust generation degree (unit: CPM, 1 CPM = 0.001 mg).
/ M ³ , and the measurement range was 0.01 to 100 mg / m ³ ).

<SDME Dryness> A scanner of an SDME tester (manufactured by Systems Engineering Co., Ltd.) is placed on an absorbent article (diaper) soaked in water so that the whole can be used, a 100% dryness value is set, and then, The detector of the SDME tester was placed on an absorbent article (diaper) dried at 100 ° C. for 5 hours to set 0% dryness, and the SDME tester was calibrated. Next, in the center of the absorbent article, the inner diameter is 6.0 cm and the height is 4.0 c.
A cylinder of m is placed, and 80 ml of artificial urine is put into the cylinder so that the absorbent absorbs the artificial urine. Leave it for 30 minutes,
Again, add 80 ml of artificial urine in the same manner. One second after the second-time artificial urine was absorbed by the absorber, the scanner was set in the center of the absorber, and the light reflectance of the surface of the center of the absorbent article was measured for 5 minutes. ). The artificial urine used here is an aqueous solution having the following composition.

[0120] Sodium chloride 0.03% by weight Magnesium sulfate 0.08% by weight Sodium chloride 0.80% by weight Urea 2.00% by weight Ion-exchanged water 97.09% by weight

<Manufacturing method of absorbent article (paper diaper)> A commercially available paper diaper (Mummy Poco: manufactured by Unicharm Co., Ltd.) is used to peel off the adhered sheet, and the pulp (P1) of the absorbent layer is peeled from the inside. Got Then, 12 g of pulp (P1) was mixed with 9 g of the water-absorbent polymer while being defibrated by hand so that the maximum diameter was 1.5 cm, and 15 × 45c
After being piled up to a size of m, the water-absorbent polymer and the pulp are mixed by pressing with a heater plate press machine N4008-00 manufactured by NPA System Co., Ltd. at 25 K at 8 Kg / cm ² for 30 seconds. The obtained absorber layer was obtained. This absorber layer was returned to the inside of the diaper from which the pulp had been taken out, and the peeled sheet was adhered by sealing using a heat sealer FI-K600-5W manufactured by FUJI IMPULSE. Then absorbent articles (paper diapers)
The whole was pressed again at 25 ° C. at 8 kg / cm ² for 30 seconds to obtain an absorbent article (paper diaper).

<Example 1> While cooling a mixed liquid of 207.7 parts of acrylic acid and 13.5 parts of water to 30 to 20 ° C, 2
346.2 parts of 5% sodium hydroxide aqueous solution was added.
An aqueous monomer solution was prepared by adding 0.10 part of potassium persulfate and 0.020 part of sodium hypophosphite to the resulting solution. Then, in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas introduction tube, cyclohexane 6 was added.
After adding 24 parts, 1.56 parts of polyoxyethylene noctyl phenyl ether phosphate (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Blysurf A210G) was added and dissolved, and then nitrogen was added while stirring at 400 rpm. After introducing the gas, the temperature was raised to 70 ° C. Then, the adjusted monomer aqueous solution was added dropwise at 6.6 parts / minute for 6 minutes while maintaining the temperature at 70 ° C. After the dropping was completed, the mixture was kept at 75 ° C. for 15 minutes and then dropped at 6.6 parts / minute over 54 minutes. Then, it was aged at 75 ° C. for 30 minutes. Then, water was removed by azeotropic distillation with cyclohexane until the water content of the resin reached about 20% (measured with an infrared moisture meter (FD-100 type, manufactured by Kett)). When the mixture was cooled to 30 ° C. and the stirring was stopped, the resin particles settled, so the resin particles were separated from the cyclohexane by decantation.

80 parts of the resin particles and 14 parts of cyclohexane
0 part and 0 parts were placed in an eggplant flask, and 0.35% by weight of glycerin polyglycidyl ether (Nagase Kasei Co., Ltd., trade name: Denacol EX-314) and a perfluoroalkylethylene oxide adduct (Dainippon Ink and Chemicals, Inc.
Product name: Megafac F-142D, surface tension: 19.
0) Cyclohexane solution containing 0.025% by weight 3.4
After adding the parts, the mixture was heated at 60 ° C. and held for 30 minutes, and then further heated and kept under reflux of cyclohexane for 30 minutes. Next, the resin particles were collected by filtration and dried under reduced pressure at 80 ° C. to obtain a water absorbent polymer (E1).
The water-absorbent polymer (E1) had a fractal order of 1.8 and a weight average particle diameter of 355 μm. Water-absorbing polymer (E1)
Table 1 shows the performance evaluation results of the absorbent articles prepared using (E1) and (E1).

Example 2 In Example 1, a polypropylene maleic anhydride modified product [Sanyo Kasei Co., Ltd., trade name: Umex 100TS, surface tension 26.0] is used in place of the perfluoroalkylethylene oxide adduct. In the same manner as in Example 1, a water absorbent polymer (E2) of the present invention was obtained. The fractal order of the obtained (E2) was 1.8 and the weight average particle diameter was 355 μm. Table 1 shows the performance evaluation results of the absorbent articles produced using the obtained (E2) and (E2).

<Example 3> In Example 1, except that an ethylene oxide-modified silicone [Shin-Etsu Chemical Co., Ltd., trade name: KF-351, surface tension 22.0] is used in place of the perfluoroalkylethylene oxide adduct. In the same manner as in Example 1, a water absorbent polymer (E3) of the present invention was obtained. The fractal order of the obtained (E3) was 1.8 and the weight average particle size was 355 μm. Table 1 shows the performance evaluation results of the absorbent articles obtained by using the obtained (E3) and (E3).

Example 4 Acrylic acid (145.4 parts) was diluted with 9.4 parts of water and cooled to 30 to 20 ° C. for 25 hours.
% Sodium hydroxide aqueous solution 242.3 parts was added to neutralize. Ethylene glycol diglycidyl ether (Denacol EX-810, manufactured by Nagase Kasei Co., Ltd.) was added to this solution.
0.0727 parts, and sodium hypophosphite monohydrate to 0.0
146 parts and 0.0727 parts of potassium persulfate were added and dissolved to obtain a monomer aqueous solution. 624 parts of cyclohexane was placed in a four-necked round bottom flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas introduction tube, and polyoxyethylene octyl phenyl ether phosphate (Daiichi Kogyo Seiyaku Co., Ltd. product as a dispersant was added to this. Blysurf A210G)
1.56 parts was added, and the mixture was stirred at 470 rpm for dispersion. After the flask was replaced with nitrogen, the temperature was raised to 75 ° C. and cyclohexane was distilled off. The aqueous monomer solution prepared above was added dropwise thereto at 6.6 parts / minute for 6 minutes. After the dropping was completed, the mixture was kept at 75 ° C. for 15 minutes and then dropped at 6.6 parts / minute over 54 minutes. After the dropping was completed, the mixture was kept at 75 ° C. for 30 minutes, and then dehydrated until the water content of the resin particles produced by azeotropic distillation with cyclohexane became about 20%. 80 parts of the resin particles and 140 parts of cyclohexane were placed in an eggplant flask, and glycerin polyglycidyl ether (trade name: Denacol EX-31, manufactured by Nagase Chemicals Co., Ltd.) was placed in the flask.
4) 0.35% by weight and perfluoroalkylethylene oxide adduct (Dainippon Ink and Chemicals, trade name: Megafac F-142D, surface tension: 19.0) 0.025
After adding 3.4 parts by weight of a cyclohexane solution, the mixture was heated at 60 ° C. for 30 minutes and then further heated and kept under reflux of cyclohexane for 30 minutes. Next, the resin particles were collected by filtration and dried under reduced pressure at 80 ° C. to obtain a water absorbent polymer (E4). The water-absorbent polymer (E4) has a fractal order of 1.6 and a weight average particle size of 2
It was 50 μm. Absorbent polymer (E4) and (E4)
Table 1 shows the performance evaluation results of the absorbent article prepared by using.

Example 5 145.4 parts of acrylic acid was diluted with 9.4 parts of water and cooled to 30 to 20 ° C. for 25 hours.
% Sodium hydroxide aqueous solution 242.3 parts was added to neutralize. 0.04 parts of N, N'-methylenebisacrylamide and 0.01 part of sodium hypophosphite monohydrate were added to this solution.
46 parts and 0.0727 parts of potassium persulfate were added and dissolved to obtain a monomer aqueous solution. Stirrer, reflux condenser,
Into a four-necked round bottom flask equipped with a thermometer and a nitrogen gas introduction tube, 624 parts of cyclohexane was placed, and polyoxyethylene octylphenyl ether phosphate (Daiichi Kogyo Seiyaku Co., Ltd., Blysurf A210G) as a dispersant was added to this.
56 parts was added and the mixture was dispersed by stirring at 470 rpm. After the flask was replaced with nitrogen, the temperature was raised to 75 ° C. and cyclohexane was distilled off. The aqueous monomer solution prepared above was added dropwise thereto at 6.6 parts / minute for 6 minutes. 75 ° C after dropping
After being held for 15 minutes, the solution was added dropwise at 6.6 parts / minute over 54 minutes. After keeping the temperature at 75 ° C for 30 minutes after the dropping,
The resin particles produced by azeotroping with cyclohexane were dehydrated until the water content became about 20%. 80 parts of the resin particles and 140 parts of cyclohexane were placed in an eggplant-shaped flask, and glycerin polyglycidyl ether (Nagase Kasei Kogyo Co., Ltd., trade name: Denacol EX-314) 0.3 was placed in the flask.
5% by weight and perfluoroalkyl ethylene oxide adduct (Dainippon Ink and Chemicals, Inc., trade name: Megafac F-
142D, surface tension: 19.0) After adding 3.4 parts of a cyclohexane solution containing 0.025% by weight, the mixture was heated at 60 ° C. and held for 30 minutes, and then further heated and refluxed with cyclohexane for 30 minutes. Held Next, the resin particles were collected by filtration and dried under reduced pressure at 80 ° C. to obtain a water absorbent polymer (E5). The water-absorbent polymer (E5) had a fractal order of 1.6 and a weight average particle diameter of 250 μm. Table 1 shows the performance evaluation results of the absorbent articles prepared using the absorbent polymers (E5) and (E5).

Example 6 In Example 1, instead of the perfluoroalkylethylene oxide adduct, a polyether-modified silicone [Shin-Etsu Chemical Co., Ltd., trade name: K
F-353, surface tension 20.2], but in Example 1
In the same manner as described above, a water absorbent polymer (E6) of the present invention was obtained.
The fractal order of the obtained (E6) was 1.8 and the weight average particle diameter was 355 μm. Obtained (E6) and (E
Table 1 shows the performance evaluation results of the absorbent article prepared by using 6).
Shown in.

Example 7 In Example 1, instead of the perfluoroalkyl ethylene oxide adduct, an epoxy-modified silicone [Shin-Etsu Chemical Co., Ltd., trade name: X-2
2-163B, surface tension 21.0] was used to obtain a water absorbent polymer (E7) of the present invention in the same manner as in Example 1. The thus obtained (E7) had a fractal order of 1.8 and a weight average particle diameter of 355 μm. Table 1 shows the performance evaluation results of the absorbent articles obtained using the obtained (E7) and (E7).

<Example 8> In Example 1, an amino-modified silicone was used instead of the perfluoroalkylethylene oxide adduct [Shin-Etsu Chemical Co., Ltd., trade name: KF-8.
80, surface tension 21.3] and ethylene oxide-modified silicone [Shin-Etsu Chemical Co., Ltd., trade name: KF-351, surface tension 22.0] mixed at a ratio of 10: 1 and Example 1. Similarly, a water absorbent polymer (E8) of the present invention was obtained. The fractal order of the obtained (E8) was 1.8 and the weight average particle diameter was 355 μm. Table 1 shows the performance evaluation results of the absorbent articles obtained by using the obtained (E8) and (E8).

Comparative Example 1 A water absorbent polymer (E6) was obtained in the same manner as in Example 1 except that the perfluoroalkylethylene oxide adduct was not added.
The water-absorbent polymer (E6) had a fractal order of 1.8 and a weight average particle diameter of 355 μm. Water-absorbing polymer (E6)
Table 1 shows the results of performance evaluation of the absorbent article prepared by using (E6).

<Comparative Example 2> In Example 1, the perfluoroalkyl ethylene oxide adduct was not added, and
After drying under reduced pressure at 0 ° C., 0.02 part of inorganic silicon dioxide was added to obtain a water absorbent polymer (E7). Water-absorbing polymer (E
The fractal order of 7) is 1.8 and the weight average particle size is 355.
was μm. Table 1 shows the results of performance evaluation of absorbent articles prepared using the water-absorbent polymers (E7) and (E7).

Comparative Example 3 95 parts of sodium acrylate, 27 parts of acrylic acid, 0.3 part of N, N′-methylenebisacrylamide and 43 parts of deionized water were placed in a glass reaction vessel.
Charge 0 parts and stir and mix while keeping the temperature of the contents at 5 ° C.
Kept at. After flowing nitrogen into the contents,
% Aqueous solution and 1 part of 0.3% aqueous solution of ascorbic acid were added to initiate polymerization. The temperature started to rise 10 minutes after the addition of hydrogen peroxide and ascorbic acid, and reached 60 ° C. 40 minutes after the temperature started to rise. Further, polymerize at 60 ° C for 12 hours to obtain a water-containing resin (W
A1) was obtained. This water-containing resin (WA1) is added to 130 to 15
Dry with hot air at 0 ° C for 20 minutes, crush with a juicer mixer and pass through a 150 mesh JIS standard sieve 2
The particle size was adjusted by obtaining particles that passed through a 0-mesh JIS standard sieve to obtain a water-absorbent polymer of 105 to 840 μm.

An infrared moisture meter (F
The water content measured with a D-100 type, manufactured by Kett) was 15%. 100 parts of the water-absorbent resin particles obtained were placed in a table-top kneader (PN-1 type, manufactured by Irie Shokai), and a perfluoroalkylethylene oxide adduct [Dainippon Ink and Chemicals, Megafac F-142D, surface tension 19 was added thereto. ．
0] 0.02 part was added, and the mixture was heated at 25 ° C. for 30 minutes for 50 r.
Stirred at pm. While stirring 100 g of the resulting water-absorbent resin particles with a table-type kneader at 50 rpm, 1 part of a 10% aqueous solution of ethylene glycol diglycidyl ether was sprayed, and the vicinity of the surface was crosslinked by heat treatment at about 140 ° C. for 30 minutes. A treated water-absorbent polymer was obtained. Further, the mixture was heated at about 140 ° C. to adjust the water content to 5% to obtain a water absorbent polymer (E8). The water-absorbent polymer (E8) had a fractal order of 1.9 and a weight average particle diameter of 390 μm. Table 1 shows the performance evaluation results of the absorbent articles prepared using the water-absorbent polymers (E8) and (E8).

<Comparative Example 4> In Comparative Example 3, a perfluoroalkylethylene oxide adduct was not added, and a polypropylene-maleic anhydride modified product [SANYO CHEMICAL INDUSTRIES, LTD.
Product name: Umex 100TS, surface tension 26.0]
Except that the water-absorbing polymer (E
8) was obtained. The water-absorbent polymer (E9) had a fractal order of 1.9 and a weight average particle diameter of 390 μm. Table 1 shows the results of performance evaluation of absorbent articles prepared using the water-absorbent polymers (E9) and (E9).

Comparative Example 5 A water absorbent polymer (E10) was obtained in the same manner as in Example 5, except that the perfluoroalkylethylene oxide adduct was not added. The fractal order of the water absorbent polymer (E10) is 1.
6, the weight average particle diameter was 250 μm. Table 1 shows the performance evaluation results of the absorbent articles prepared using the water-absorbent polymers (E6) and (E6).

[0137]

[Table 1] * The particle size of all the water-absorbent polymers of Examples and Comparative Examples is 1
The particle size of 05-840 μm was 95% or more.

As can be seen from Table 1, the water-absorbing polymers of the present invention (Examples 1 to 8) have an absorption capacity under pressure equal to or higher than those of Comparative Examples 1 to 5 and have good absorption. SDME dryness is shown. Further, the initial absorption amount under pressure and dust generation of the water-absorbent polymer of the present invention show values superior to those of Comparative Examples. Further, the water-absorbent polymer of the present invention has a higher dust generation degree and SDME than Comparative Examples 3 and 4 which have a large fractal order.
The dryness is equal to or higher than that, and the absorption performance under pressure (initial absorption amount and absorption capacity) is excellent.

[0139]

The water-absorbent polymer of the present invention exerts an extremely excellent effect on dryness while maintaining the absorbability under pressure, which is essential for water-absorbent resins. Further, it exhibits an excellent effect in terms of dust generation.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) A61F 13/53 A61F 13/18 307B C08K 5/00 A41B 13/02 D C08L 101/00 F term (reference) 3B029 BA17 4C003 AA24 4J002 BB21X BG01W CH01X CP03X CP18X GB00

Claims (4)

[Claims] 1. A cross-linked polymer (A) having (meth) acrylic acid (salt) as a main constituent unit and a fractal order of 1.8 or less, and a surface modifier (B). Water-absorbing polymer. 2. The surface modifier (B) has a bonding group capable of chemically bonding to the crosslinked polymer (A), and the surface tension of (B) is 10 to 30 dynes / cm. The water-absorbing polymer described. 3. The water absorbent polymer according to claim 1, wherein the surface modifier (B) is an organic compound (B1) having a hydrocarbon group which may contain a fluorine atom or a silicone compound (B2). . 4. An absorbent article comprising the water-absorbent polymer according to claim 1.