JP2022075672A - Manufacturing method of absorbent article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an absorbent article excellent in shape retention properties of an absorber even when an external force is applied.

SOLUTION: Provided is a manufacturing method of an absorbent article including an absorber which contains water absorbing resin particles (P) including a water-soluble vinyl monomer (a1) and/or a hydrolysable vinyl monomer (a2) and a crosslinked polymer (A) containing a crosslinking agent (b) as an indispensable constituent, a liquid diffusion member (B) and a 0.05-20 wt.% gel particle shape retaining agent (C) based on the weight of (B), that is, the absorber in which (C) is a cationic organic polymer (c2) preferably with a number-average molecular weight of 400000-950000, such as poly(dimethylaminoethyl methacrylate), sulfate, or the like. The manufacturing method of the absorbent article includes a step to homogeneously mix the gel particle shape retaining agent (C) with the water absorbing resin particles (P) before constituting the absorber, and a step to adhere what is obtained by homogeneously mixing (C) and (P) onto the surface of the liquid diffusion member (B).

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to an absorbent article. More specifically, children's disposable diapers, adult disposable diapers, medical blood-retaining agents, pet sheets, panty liners, incontinence pads, sweat-absorbing sheets, medical blood-absorbing articles, wound protectants, wound healing agents and surgical wastewater treatment agents. And the like.

Absorbent articles having an aqueous liquid absorber in which crosslinked polymer particles such as water-absorbent resin particles and hydrophilic fibers such as pulp are mixed, and a tissue or non-woven fabric arranged on the upper surface of the aqueous liquid absorber are widely known. (See, for example, Patent Document 1). An absorbent article having such a structure has an excellent absorbing ability, but in actual use, the attached absorbent article moves or a constant force is continuously or discontinuously applied to the absorber. If the absorber after absorption of the liquid is torn or twisted, the ability to repeatedly absorb the liquid is lowered, which causes a problem of liquid leakage and skin rash and the like.

A technology to improve the adhesion and entanglement between water-absorbent resin particles and pulp by optimizing the composition of the hot-melt adhesive used to fix the absorber in order to suppress the decrease in absorption capacity due to tearing or twisting of the absorber. (See, for example, Patent Document 2). However, in this method, the shape retention of the absorber is not sufficient, and the effect of suppressing the deterioration of the absorption performance due to the tearing or twisting of the absorber is not sufficient.

Japanese Patent No. 3916852 Japanese Patent No. 5404959

An object of the present invention is to provide a method for producing an absorbent article having excellent shape retention of an absorber even when a force is applied from the outside.

A water-absorbent resin having a water-soluble vinyl monomer (a1) and / or a cross-linked polymer (A) containing a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis and a cross-linking agent (b) as essential constituent units. An absorber containing 0.05 to 20% by weight of a gel particle shape-retaining agent (C) based on the weight of the particles (P), the liquid diffusing member (B), and the liquid diffusing member (B). The gel particle shape-retaining agent (C) is an absorber, which is a cationic organic polymer (c2) having a number average molecular weight of 400,000 to 5 million and having a structural unit represented by the following general formula (1). A step of uniformly mixing a gel particle shape-retaining agent (C) with a water-absorbent resin particle (P) before forming an absorber, and a gel particle shape-retaining agent. A method for producing an absorbent article, which comprises a step of uniformly mixing (C) and water-absorbent resin particles (P) and adhering the mixture to the surface of the liquid diffusion member (B).

［式中、Ｒ^１及びＲ^２は、同一又は異なって、水素原子または炭素数１～４のアルキル基であり、Ｒ^３は水素原子またはメチル基であり、Ｑは炭素数１～４のアルキレン基であり、Ｘは酸素原子またはイミノ基であり、Ｚ^－はブレンステッド酸の共役塩基を表す。］

[In the formula, R ¹ and R ² are the same or different, an alkyl group having a hydrogen atom or 1 to 4 carbon atoms, R ³ is a hydrogen atom or a methyl group, and Q is an alkylene having 1 to 4 carbon atoms. A group, X is an oxygen atom or an imino group, and Z ^- represents a conjugated base of Bronsted acid. ]

The absorbent article of the present invention uses a cationic organic polymer (c2) having a cationic group, which is a salt of an amino group (am), as a gel particle shape-retaining agent (C) in the above-mentioned structure, especially in the absorber. By using it as an essential component, it has excellent absorbency shape retention even when an external force is applied, and even if a constant force is continuously or discontinuously applied to the absorber, compared to conventional absorbent articles. The absorber does not rupture or twist, there is little liquid leakage due to a decrease in absorption capacity, and it is unlikely to cause skin rash or the like.

The absorbent article of the present invention is a vinyl monomer (a2) that becomes a water-soluble vinyl monomer (a1) and / or a water-soluble vinyl monomer (a1) by hydrolysis (hereinafter, also referred to as a hydrolyzable vinyl monomer (a2)). Further, it comprises an absorber containing a water-absorbent resin particle (P) having a cross-linking polymer (A) having a cross-linking agent (b) as an essential constituent unit and a liquid diffusion member (B), and the absorber is provided. Further, it contains a gel particle shape-retaining agent (C).

In the absorbent article of the present invention, as described above, the composition containing the water-absorbent resin particles (P) and the liquid diffusion member (B) is referred to as an absorber.

The crosslinked polymer (A) contained in the water-absorbent resin particles (P) contains a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) and a crosslinking agent (b) as essential constituent units.

The water-soluble vinyl monomer (a1) in the present invention is not particularly limited, and is a known monomer, for example, at least one water-soluble substituent disclosed in paragraphs 0007 to 0023 of Japanese Patent No. 36485553 and ethylenia-free. Vinyl monomers having a saturated group (for example, anionic vinyl monomers, nonionic vinyl monomers and cationic vinyl monomers), anionic vinyl monomers and nonionic vinyl monomers disclosed in paragraphs 0009 to 0024 of JP-A-2003-165883. Select from the group consisting of a sex vinyl monomer, a cationic vinyl monomer, and a carboxy group, a sulfo group, a phosphono group, a hydroxyl group, a carbamoyl group, an amino group, and an ammonio group disclosed in paragraphs 0041 to 0051 of JP-A-2005-75982. A vinyl monomer having at least one of these can be used.

The hydrolyzable vinyl monomer (a2) is not particularly limited, and for example, at least one hydrolyzable substituent which becomes a water-soluble substituent by hydrolysis disclosed in paragraphs 0024 to 0025 of Japanese Patent No. 3648553 is used. A vinyl monomer having at least one hydrolyzable substituent [1,3-oxo-2-oxapropylene (-CO-O-CO-) disclosed in paragraphs 0052 to 0055 of JP-A-2005-75982. ) Group, acyl group, cyano group, etc.] can be used. The water-soluble vinyl monomer is a concept well known to those skilled in the art, but when expressed using a quantity, it means, for example, a vinyl monomer that dissolves at least 100 g in 100 g of water at 25 ° C. Further, the hydrolytic property of the hydrolyzable vinyl monomer (a2) is a concept well known to those skilled in the art, but more specifically, for example, by the action of water and, if necessary, a catalyst (acid or base, etc.). It means the property of being hydrolyzed and becoming water-soluble. The hydrolyzable vinyl monomer (a2) may be hydrolyzed during or after the polymerization, or both of them, but it is preferable after the polymerization from the viewpoint of the absorption performance of the obtained water-absorbent resin particles.

Of these, the water-soluble vinyl monomer (a1) is preferable from the viewpoint of absorption performance and the like, and the above-mentioned anionic vinyl monomer, carboxy (salt) group, sulfo (salt) group, amino group and carbamoyl group are more preferable. Vinyl monomers having an ammonio group or a mono-, di- or tri-alkylammonio group, more preferably a vinyl monomer having a carboxy (salt) group or a carbamoyl group, particularly preferred are (meth) acrylic acid (salt) and (Meta) acrylamide, particularly preferred is (meth) acrylic acid (salt), most preferred is acrylic acid (salt).

In addition, "carboxy (salt) group" means "carboxy group" or "carboxylate group", and "sulfo (salt) group" means "sulfo group" or "sulfonate group". Further, (meth) acrylic acid (salt) means acrylic acid, acrylate, methacrylic acid or methacrylamide, and (meth) acrylamide means acrylamide or methacrylamide. Examples of the salt include alkali metal (lithium, sodium, potassium, etc.) salt, alkaline earth metal (magnesium, calcium, etc.) salt, ammonium (NH ₄ ) salt, and the like. Of these salts, alkali metal salts and ammonium salts are preferable, and alkali metal salts are more preferable, and sodium salts are particularly preferable, from the viewpoint of absorption performance and the like.

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

As a constituent unit of the crosslinked polymer (A), in addition to the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), another vinyl monomer (a3) copolymerizable with these shall be a constituent unit. Can be done. As the other vinyl monomer (a3), one type may be used alone, or two or more types may be used in combination.

The other copolymerizable vinyl monomer (a3) is not particularly limited, and is known (for example, the hydrophobic vinyl monomer disclosed in paragraphs 0028 to 0029 of Japanese Patent No. 36485553, JP-A-2003-165883). Hydrophobic vinyl monomers (such as the vinyl monomers disclosed in paragraph 0025 and paragraph 0058 of JP-A-2005-75982) can be used, and specifically, for example, the following vinyl monomers (i) to (iii) and the like can be used. Can be used.
(I) Aromatic ethylenic monomer having 8 to 30 carbon atoms Styrene such as styrene, α-methylstyrene, vinyltoluene and hydroxystyrene, halogen substituted styrene such as vinylnaphthalene and dichlorostyrene and the like.
(Ii) Alkene (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.); and alkaziene (butadiene and isoprene, etc.) having 2 to 20 carbon atoms.
(Iii) Alicyclic ethylenic monomer having 5 to 15 carbon atoms Monoethylene unsaturated monomer (pinene, limonene, indene, etc.); and polyethylene vinyl monomer [cyclopentadiene, bicyclopentadiene, etylidene norbornene, etc.] and the like.

The content (mol%) of the other vinyl monomer (a3) unit is based on the total number of moles of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit from the viewpoint of absorption performance and the like. It is preferably 0 to 5, more preferably 0 to 3, particularly preferably 0 to 2, particularly preferably 0 to 1.5, and the content of other vinyl monomer (a3) units is high from the viewpoint of absorption performance and the like. Most preferably, it is 0 mol%.

The cross-linking agent (b) is not particularly limited and reacts with a cross-linking agent having two or more ethylenically unsaturated groups and a water-soluble substituent disclosed in paragraphs 0031 to 0034 of Japanese Patent No. 3648553 (for example). JP-A-2003-165883, a cross-linking agent having at least one functional group to be obtained and having at least one ethylenically unsaturated group and a cross-linking agent having at least two functional groups capable of reacting with a water-soluble substituent. A cross-linking agent having two or more ethylenically unsaturated groups, a cross-linking agent having an ethylenically unsaturated group and a reactive functional group, and a cross-linking agent having two or more reactive substituents disclosed in paragraphs 0028 to 0031. , A cross-linking agent of the cross-linking vinyl monomer disclosed in paragraph 0059 of JP-A-2005-75982 and the cross-linking vinyl monomer disclosed in paragraphs 0015 to 0016 of JP-A-2005-59559) can be used. .. Of these, a cross-linking agent having two or more ethylenically unsaturated groups is preferable from the viewpoint of absorption performance and the like, and more preferable is a poly (triallyl cyanurate, triallyl isocyanurate and a polyol having 2 to 40 carbon atoms). Meta) Allyl ethers, particularly preferred are triallyl cyanurate, triallyl isocyanurate, tetraallyloxyetane, polyethylene glycol diallyl ether and pentaerythritol triallyl ether, most preferably pentaerythritol triallyl ether. The cross-linking agent (b) may be used alone or in combination of two or more.

The content (mol%) of the cross-linking agent (b) unit is (a1) when other vinyl monomers (a3) of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit are also used. Based on the total number of moles of (a3), 0.001 to 5, more preferably 0.005 to 3, and particularly preferably 0.01 to 1. Within this range, the absorption performance is further improved.

Examples of the polymerization method of the crosslinked polymer (A) include known solution polymerization (adiabatic polymerization, thin film polymerization, spray polymerization, etc .; JP-A No. 55-133413, etc.) and known reverse phase suspension polymerization (Tokusho). 54-30710, JP-A-56-26909, JP-A No. 1-5808, etc.).

The crosslinked polymer (A) can be obtained by polymerizing a monomer composition containing a water-soluble vinyl monomer (a1) and / or a hydrolyzable vinyl monomer (a2) and a crosslinking agent (b) as essential constituents. Can be done. Among the polymerization methods, the solution polymerization method is preferable because it does not require the use of an organic solvent and is advantageous in terms of production cost, and the aqueous solution polymerization method and the aqueous solution polymerization method are more preferable because of the entanglement with the liquid diffusion member (B). It is a reverse phase suspension polymerization method.

When performing aqueous solution polymerization, a mixed solvent containing water and an organic solvent can be used, and the organic solvent includes methanol, ethanol, acetone, methyl ethyl ketone, N, N-dimethylformamide, dimethyl sulfoxide, and two or more of these. Can be mentioned as a mixture of.
In the case of aqueous solution polymerization, the amount (% by weight) of the organic solvent used is preferably 40 or less, more preferably 30 or less, based on the weight of water.

When an initiator is used for polymerization, conventionally known initiators for radical polymerization can be used. For example, azo compounds [azobisisobutyronitrile, azobiscyanovaleric acid and 2,2'-azobis (2-amidinopropane)) can be used. Hydrochloride, etc.], Inorganic peroxides (hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, etc.), organic peroxides [benzoyl peroxide, dit-butyl peroxide, cumene hydroperoxide, succinic acid, etc.] Acid peroxides and di (2-ethoxyethyl) peroxydicarbonates, etc.] and redox catalysts (alkali metal sulfites or bisulfites, reducing agents such as ammonium sulfite, ammonium bicarbonate and ascorbic acid, and alkali metal persulfates. (Combined with an oxidizing agent such as a salt, ammonium persulfate, hydrogen peroxide and an organic peroxide) and the like. These catalysts may be used alone or in combination of two or more of them.
The amount (% by weight) of the radical polymerization initiator used is (a1) to (a3) when other vinyl monomers (a3) of the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are also used. Based on the total weight of the above, 0.0005 to 5 is preferable, and 0.001 to 2 is more preferable.

At the time of polymerization, a polymerization control agent typified by a chain transfer agent may be used in combination, and specific examples thereof include sodium hypophosphite, sodium phosphite, alkyl mercaptans, and alkyl halides. , Thiocarbonyl compounds and the like. These polymerization control agents may be used alone or in combination of two or more of them.
The amount (% by weight) of the polymerization control agent used is that of the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2), and when other vinyl monomers (a3) are also used, the amounts thereof are (a1) to (a3). , 0.0005 to 5, more preferably 0.001 to 2, based on the total weight.

When a suspension polymerization method or a reverse phase suspension polymerization method is used as the polymerization method, the polymerization may be carried out in the presence of a dispersant or a surfactant, if necessary. Further, in the case of the reverse phase suspension polymerization method, the polymerization can be carried out using a hydrocarbon solvent such as xylene, normal hexane and normal heptane.

The polymerization start temperature can be appropriately adjusted depending on the type of catalyst used, but is preferably 0 to 100 ° C, more preferably 2 to 80 ° C.

When a solvent (organic solvent, water, etc.) is used for the polymerization, it is preferable to distill off the solvent after the polymerization. When the solvent contains an organic solvent, the content (% by weight) of the organic solvent after distillation is preferably 0 to 10, more preferably 0 to 5, and particularly preferably 0 to 5, based on the weight of the crosslinked polymer (A). Is 0 to 3, most preferably 0 to 1. Within this range, the absorption performance of the water-absorbent resin particles is further improved.

When water is contained in the solvent, the water content (% by weight) after distillation is preferably 0 to 20, more preferably 1 to 10, particularly preferably 2 to 9, based on the weight of the crosslinked polymer (A). Most preferably, it is 3 to 8. Within this range, the absorption performance is further improved.

By the above-mentioned polymerization method, a water-containing gel-like substance (that is, a cross-linked polymer (A) which is a water-containing gel-like substance; hereinafter abbreviated as a water-containing gel) can be obtained. Further, the dried crosslinked polymer (A) can be obtained by drying the hydrogel.
When an acid group-containing monomer such as acrylic acid or methacrylic acid is used as the water-soluble vinyl monomer (a1), the water-containing gel may be neutralized with a base. The degree of neutralization of the acid group is preferably 50 to 80 mol%. When the degree of neutralization is less than 50 mol%, the adhesiveness of the obtained hydrogel polymer may be high, and the workability during production and use may be deteriorated. Further, the amount of water retention of the obtained water-absorbent resin particles may decrease. On the other hand, when the degree of neutralization exceeds 80%, the pH of the obtained resin becomes high, and there may be a concern about the safety of the human body on the skin.
The neutralization may be performed at any stage after the polymerization of the crosslinked polymer (A) in the production of the water-absorbent resin particles, and for example, a method of neutralizing in the state of a hydrogel is preferable. Illustrated.
As the base to be neutralized, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates such as sodium carbonate, sodium hydrogencarbonate and potassium carbonate can be usually used.

The hydrogel obtained by polymerization can be shredded as needed. The size (longest diameter) of the gel after shredding is preferably 50 μm to 10 cm, more preferably 100 μm to 2 cm, and particularly preferably 1 mm to 1 cm. Within this range, the drying property in the drying step is further improved.

Shredding can be performed by a known method, and can be shredded using a normal shredding device {for example, a Beck's mill, a rubber chopper, a pharma mill, a minced machine, an impact crusher and a roll crusher}. ..

As a method for distilling off the solvent (including water), a method of distilling off (drying) with hot air at a temperature of 80 to 230 ° C., a thin film drying method using a drum dryer heated to 100 to 230 ° C., etc. (heating). ) Vacuum drying method, freeze drying method, infrared drying method, decantation, filtration, etc. can be applied.

The water-containing gel can be dried to obtain a crosslinked polymer (A), and then dried and then pulverized. The crushing method is not particularly limited, and a normal crushing device {for example, a hammer type crusher, an impact type crusher, a roll type crusher, a shet airflow type crusher} or the like can be used. The particle size of the pulverized crosslinked polymer can be adjusted by sieving or the like, if necessary.

The weight average particle size (μm) of the crosslinked polymer (A) when screened as necessary is preferably 100 to 800, more preferably 200 to 700, then preferably 250 to 600, and particularly preferably 300 to 500. Most preferably, it is 350 to 450. Within this range, the absorption performance is further improved, the entanglement with the liquid diffusion member (B) is also improved, and the shape retention is good.

The weight average particle size was determined by using a low-tap test sieve shaker and a standard sieve (JIS Z8801-1: 2006), Perry's Chemical Engineers Handbook 6th Edition (McGlow Hill Book Canvas, 1984). , Page 21). That is, the JIS standard sieves are combined in the order of 1000 μm, 850 μm, 710 μm, 500 μm, 425 μm, 355 μm, 250 μm, 150 μm, 125 μm, 75 μm and 45 μm, and the saucer from the top. Place about 50 g of the measurement particles in the uppermost sieve and shake with a low-tap test sieve shaker for 5 minutes. Weigh the measured particles on each sieve and saucer, and set the total to 100% by weight to obtain the weight fraction of the particles on each sieve. ), The vertical axis is the weight fraction}, then a line connecting each point is drawn to obtain the particle diameter corresponding to the weight fraction of 50% by weight, and this is used as the weight average particle diameter.

Further, when pulverized, the smaller the content of the fine particles contained in the crosslinked polymer (A) after pulverization, the better the absorption performance. Therefore, the total weight of the crosslinked polymer (A) is 106 μm or less (preferably 150 μm). The content (% by weight) of the fine particles (below) is preferably 3 or less, more preferably 1 or less. The content of the fine particles can be determined by using the graph created when determining the weight average particle diameter described above.

When pulverized, the shape of the crosslinked polymer (A) after pulverization is not particularly limited, and examples thereof include amorphous crushed form, phosphorus fragment form, pearl form, and rice granules. Of these, the amorphous crushed form is preferable from the viewpoint of good entanglement with the liquid diffusion member (B) and no fear of falling off from the fibrous material.

The crosslinked polymer (A) may contain some other components such as a residual solvent and a residual crosslinked component as long as the performance is not impaired.

The crosslinked polymer (A) preferably contains a hydrophobic substance (g) from the viewpoint of surface modification and liquid permeability.

Examples of the hydrophobic substance (g) include a hydrophobic substance containing a hydrocarbon group (g1), a hydrophobic substance containing a hydrocarbon group having a fluorine atom (g2), and a hydrophobic substance having a polysiloxane structure (g3). Etc. are included.

Examples of the hydrophobic substance (g1) containing a hydrocarbon group include polyolefin resins, polyolefin resin derivatives, polystyrene resins, polystyrene resin derivatives, waxes, long-chain fatty acid esters, long-chain fatty acids and salts thereof, long-chain aliphatic alcohols, and long chains. Chain fatty acid amides and mixtures of two or more of these are included.

As the polyolefin resin, the weight of an olefin having 2 to 4 carbon atoms {ethylene, propylene, isobutylene, isoprene, etc.} as an essential constituent monomer (the content of the olefin is at least 50% by weight based on the weight of the polyolefin resin). Polymers having an average molecular weight of 10 to 1,000,000 {for example, polyethylene, polypropylene, polyisobutylene, poly (ethylene-isobutylene), isoprene, etc.} can be mentioned.

As the polyolefin resin derivative, a polymer having a weight average molecular weight of 10 to 1,000,000 in which a carboxy group (-COOH), 1,3-oxo-2-oxapropylene (-COOCO-), etc. are introduced into a polyolefin resin {for example, polyethylene heat Attenuated product, heat-decomposed product of polypropylene, maleic acid-modified polyethylene, chlorinated polyethylene, maleic acid-modified polypropylene, ethylene-acrylic acid copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, maleinized Polybutadiene, ethylene-vinyl acetate copolymer, maleinate of ethylene-vinyl acetate copolymer, etc.} can be mentioned.

As the polystyrene resin, a polymer having a weight average molecular weight of 10 to 1,000,000 can be used.

As the polystyrene resin derivative, a polymer having a weight average molecular weight of 10 to 1,000,000 containing styrene as an essential constituent monomer (the content of styrene is at least 50% by weight based on the weight of the polystyrene derivative) {for example, styrene-. Maleic anhydride copolymer, styrene-butadiene copolymer, styrene-isobutylene copolymer, etc.} can be mentioned.

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

Examples of the long-chain fatty acid ester include esters of fatty acids having 8 to 30 carbon atoms and alcohols having 1 to 12 carbon atoms {for example, methyl laurate, ethyl laurate, methyl stearate, ethyl stearate, methyl oleate, oleic acid. Ethyl, glycerin lauric acid monoester, glycerin stearate monoester, glycerin oleic acid monoester, pentaerythlit lauric acid monoester, pentaerythlit lauric acid monoester, pentaerythlit oleic acid monoester, sorbit lauric acid monoester, Solbit stearate monoester, sorbit oleic acid monoester, sucrose palmitic acid monoester, sucrose palmitate diester, sucrose palmitate triester, sucrose stearate monoester, sucrose stearate diester, sucrose stearate tri. Esters, beef fat, etc.} can be mentioned.

Examples of the long-chain fatty acid and its salt include fatty acids having 8 to 30 carbon atoms {for example, lauric acid, palmitic acid, stearic acid, oleic acid, dimer acid, behenic acid, etc.}, and examples thereof include zinc, calcium, and the like. Examples thereof include salts with magnesium or aluminum (hereinafter abbreviated as Zn, Ca, Mg, Al, respectively) {for example, Ca palmitate, Al palmitate, Ca stearate, Mg stearate, Al stearate, etc.}.

Examples of the long-chain fatty alcohol include fatty alcohols having 8 to 30 carbon atoms {for example, lauryl alcohol, palmityl alcohol, stearyl alcohol, oleyl alcohol, etc.}. From the viewpoint of leakage resistance of the absorbent article, palmityl alcohol, stearyl alcohol, and oleyl alcohol are preferable, and stearyl alcohol is more preferable.

The long-chain fatty acid amide is an amidate of a long-chain fatty acid primary amine having 8 to 30 carbon atoms and a carboxylic acid having a hydrocarbon group having 1 to 30 carbon atoms, ammonia or a primary amine having 1 to 7 carbon atoms. And an amidate of a long-chain fatty acid having 8 to 30 carbon atoms, an amidate of a long-chain aliphatic secondary amine having at least one aliphatic chain having 8 to 30 carbon atoms and a carboxylic acid having 1 to 30 carbon atoms, and Examples thereof include amidates of a secondary amine having two aliphatic hydrocarbon groups having 1 to 7 carbon atoms and a long-chain fatty acid having 8 to 30 carbon atoms.

As an amidate of a long-chain aliphatic primary amine having 8 to 30 carbon atoms and a carboxylic acid having a hydrocarbon group having 1 to 30 carbon atoms, a reaction of a primary amine and a carboxylic acid in a ratio of 1: 1 and 1 : Divided into those that reacted in 2. Examples of the 1: 1 reaction include acetic acid N-octylamide, acetate N-hexacosylamide, heptacosanoic acid N-octylamide, and heptacosanoic acid N-hexacosylamide. Examples of the 1: 2 reaction include diacetic acid N-octylamide, diacetic acid N-hexacosylamide, diheptacosanoic acid N-octylamide and diheptacosanoic acid N-hexacosylamide. When the primary amine and the carboxylic acid are reacted in a ratio of 1: 2, the carboxylic acid used may be the same or different.

The amidate of ammonia or a primary amine having 1 to 7 carbon atoms and a long-chain fatty acid having 8 to 30 carbon atoms is 1: 2 with a 1: 1 reaction of ammonia or a primary amine with a carboxylic acid. It is divided into those that have reacted. The 1: 1 reaction products include nonanoic acid amide, nonanoic acid methylamide, nonanoic acid N-heptylamide, heptacosanoic acid amide, heptacosanoic acid N-methylamide, heptacosanoic acid N-heptylamide and heptacosanoic acid N-hexacosylamide. And so on. The 1: 2 reaction was dinonanoic acid amide, dinonanoic acid N-methylamide, dinonanoic acid N-heptylamide, dioctadecanoic acid amide, dioctadecanic acid N-ethylamide, dioctadecanic acid N-heptylamide, diheptacosanoic acid amide. , Diheptacosanoic acid N-methylamide, diheptacosanoic acid N-heptylamide, diheptacosanoic acid N-hexacosylamide and the like. As for the product obtained by reacting ammonia or a primary amine with a carboxylic acid in a ratio of 1: 2, the carboxylic acid used may be the same or different.

Examples of the amidate of a long-chain aliphatic secondary amine having at least one aliphatic chain having 8 to 30 carbon atoms and a carboxylic acid having 1 to 30 carbon atoms include N-methyloctylamide acetate and N-methylhexakoshi acetate. Luamide, N-octylhexacosylamide acetate, N-dihexacosylamide acetate, N-methyloctylamide heptacosanoic acid, N-methylhexacosylamide heptacosanoic acid, N-octylhexacosylamide heptacosanoate and heptacosane Acid N-dihexacosylamide and the like can be mentioned.

Examples of the amidate of the secondary amine having two aliphatic hydrocarbon groups having 1 to 7 carbon atoms and the long chain fatty acid having 8 to 30 carbon atoms include nonanoic acid N-dimethylamide and nonanoic acid N-methylheptylamide. Examples thereof include nonanoic acid N-diheptylamide, heptacosanoic acid N-dimethylamide, heptacosanoic acid N-methylheptylamide and heptacosanoic acid N-diheptylamide.

Hydrophobic substances (g2) containing a hydrocarbon group having a fluorine atom include perfluoroalkane, perfluoroalkene, perfluoroaryl, perfluoroalkyl ether, perfluoroalkylcarboxylic acid, perfluoroalkyl alcohol and 2 of these. A mixture of seeds or more is included.

Examples of the hydrophobic substance (g3) having a polysiloxane structure include polydimethylsiloxane, polyether-modified polysiloxane {polyoxyethylene-modified polysiloxane and poly (oxyethylene / oxypropylene) -modified polysiloxane}, carboxy-modified polysiloxane, and the like. Includes epoxy-modified polysiloxanes, amino-modified polysiloxanes, alkoxy-modified polysiloxanes and the like, and mixtures thereof.

The HLB value of the hydrophobic substance (g) is preferably 1 to 10, more preferably 2 to 8, and particularly preferably 3 to 7. Within this range, the leak resistance of the absorbent article becomes even better. The HLB value means a hydrophilic-hydrophobic balance (HLB) value, and is obtained by the Oda method (Introduction to New Surfactants, p. 197, Takehiko Fujimoto, published by Sanyo Chemical Industries, Ltd., 1981). ..

Among the hydrophobic substances (g), the hydrophobic substance (g1) containing a hydrocarbon group is preferable, and more preferably a long-chain fatty acid ester, a long-chain fatty acid and a salt thereof, from the viewpoint of leakage resistance of the absorbent article. Long-chain aliphatic alcohols and long-chain aliphatic amides, more preferably sorbit stearic acid ester, sucrose stearic acid ester, stearic acid, Mg stearate, Ca stearate, Zn stearate and Al stearate, particularly preferably. Sucrose stearic acid ester and stearic acid Mg, most preferably sucrose stearic acid monoester.

The water-absorbent resin particles of the present invention preferably have a structure in which the surface of the crosslinked polymer (A) is crosslinked by the surface crosslinking agent (d). By cross-linking the surface of the crosslinked polymer (A), the gel strength of the water-absorbent resin particles can be improved, and the desirable water-retaining amount of the water-absorbent resin particles and the absorption amount under load can be satisfied. Examples of the surface cross-linking agent (d) include polyvalent glycidyl compounds, polyvalent amines, polyvalent aziridine compounds and polyhydric isocyanate compounds described in JP-A-59-189103, and JP-A-58-180233. And the polyhydric alcohol of JP-A-61-16903, the silane coupling agent described in JP-A-61-21305 and JP-A-61-252212, and described in JP-A-5-508425. Uses alkylene carbonates, polyvalent oxazoline compounds described in JP-A-11-240959, and surface cross-linking agents of JP-A-51-136588 and JP-A-61-257235 (polyvalent metals, etc.). can. Among these surface cross-linking agents, polyhydric glycidyl compounds, polyhydric alcohols and polyhydric amines are preferable, and polyhydric glycidyl compounds and polyhydric alcohols are more preferable, and polyhydric alcohols are particularly preferable, from the viewpoint of economic efficiency and absorption characteristics. Valuable glycidyl compounds, most preferably ethylene glycol diglycidyl ethers. One type of surface cross-linking agent may be used alone, or two or more types may be used in combination.

In the case of surface cross-linking, the amount (% by weight) of the surface cross-linking agent used is not particularly limited because it can be variously changed depending on the type of the surface cross-linking agent, the conditions for cross-linking, the target performance, etc. From the viewpoint and the like, it is preferably 0.001 to 3, more preferably 0.005 to 2, and particularly preferably 0.01 to 1.5 with respect to 100 parts by weight of the crosslinked polymer (A).

The surface cross-linking of the cross-linked polymer (A) can be carried out by mixing the cross-linked polymer (A) and the surface cross-linking agent (d) and heating as necessary. As a method of mixing the crosslinked polymer (A) and the surface crosslinking agent (d), a cylindrical mixer, a screw type mixer, a screw type extruder, a turbulizer, a Nauter type mixer, a double arm type kneader, and a flow Cross-linking polymer (A) and surface cross-linking using a mixer such as a type mixer, V-type mixer, minced mixer, ribbon type mixer, air flow type mixer, rotary disk type mixer, conical blender and roll mixer. Examples thereof include a method of uniformly mixing the agent (d). At this time, the surface cross-linking agent (d) may be diluted with water and / or any solvent before use.

The temperature at which the crosslinked polymer (A) and the surface crosslinking agent (d) are mixed is not particularly limited, but is preferably 10 to 150 ° C, more preferably 20 to 100 ° C, and particularly preferably 25 to 80 ° C. ..

After mixing the crosslinked polymer (A) and the surface crosslinking agent (d), heat treatment is performed. The heating temperature is preferably 100 to 180 ° C., more preferably 110 to 175 ° C., and particularly preferably 120 to 170 ° C. from the viewpoint of breakage resistance of the resin particles. Indirect heating using steam is possible if the heating is 180 ° C or lower, which is advantageous in terms of equipment, and if the heating temperature is lower than 100 ° C, the absorption performance may deteriorate. The heating time can be appropriately set depending on the heating temperature, but is preferably 5 to 60 minutes, more preferably 10 to 40 minutes from the viewpoint of absorption performance. It is also possible to further surface-crosslink the water-absorbent resin obtained by surface-crosslinking with a surface-crosslinking agent of the same type or different from the surface-crosslinking agent used first.

After the surface of the crosslinked polymer (A) is crosslinked with the surface crosslinking agent (d), the particle size is adjusted by sieving if necessary. The average grain diameter of the obtained particles is preferably 100 to 600 μm, more preferably 200 to 500 μm. The content of the fine particles is preferably small, the content of the particles of 100 μm or less is preferably 3% by weight or less, and the content of the particles of 150 μm or less is more preferably 3% by weight or less.

The water-absorbent resin particles (P) may contain a cationic organic polymer (c) having a molecular weight of less than 1 million.
As the cationic organic polymer (c), an organic polymer having a cationic group (amino group, ammonio group, imino group, iminium group, phosphino group, phosphonium group, sulfonium group, etc.) can be used, and it is easy to synthesize. From the viewpoint of the above, a polymer having an amino group and / or an ammonio group as a cationic group is preferable.

Among the polymers having an amino group and / or the ammonio group, the cationic organic polymer having an amino group can be obtained by polymerizing a monomer having an amino group, and the cationic organic polymer containing an ammonio group (c). ) Is a method of polymerizing a monomer having an ammonio group, a method of reacting a cationic organic polymer having an amino group with an electromotive reagent, and a method of reacting a monomer having an amino group with a salvage reagent. It can be obtained by a polymerization method. Polymers with amino and ammonio groups can be obtained by combining these methods.
As the electrophilic reagent, a compound described later can be used. Only one type of these electrophiles may be used, or two or more types may be used in combination.

Examples of the cationic organic polymer (c) include polyallylamine, polydiallylamine, poly (N-alkylallylamine), poly (alkyldiallylamine), monoallylamine-diallylamine copolymer, N-alkylallylamine-monoallylamine copolymer, and mono. Allylamine-dialkyldiallylammonium salt / copolymer, diallylamine-dialkyldiallylammonium salt / copolymer, polyaminoethyl (meth) acrylate, polydimethylaminoethyl (meth) acrylate, polydiethylaminoethyl (meth) acrylate, polydimethylaminoethyl (Meta) acrylamide, homopolymer of alkylaminoethyl (meth) acrylate quaternary salt, alkylaminoethyl (meth) acrylate quaternary salt-acrylamide / copolymer, linear polyethylene imine, branched chain polyethylene imine, polyethylene Examples thereof include polyamines, polypropylene polyamines, polyamide polyamines, polyether polyamines, polyvinylamines, polyamide polyamines / epichlorohydrin resins, and polyamidins. Further, an aminated modified product obtained by reacting formaldehyde and diethylamine with polyacrylamide or polymethacrylamide can also be mentioned.

The cationic organic polymer (c) having an amino group and / or an ammonio group polymerizes a monomer having an amino group and / or a monomer having an ammonio group by a known polymerization method (method described in, etc.). It can also be obtained from the market as a polymer flocculant and a dye fixing agent.

The cationic organic polymer (c) may be in the form of a salt with an anion which is a conjugate base of a strong acid. Examples of the strong acid include inorganic acids and organic acids. Among the inorganic acid and the organic acid, a strong acid having a molecular weight of 30 to 300 is preferable, and preferred strong acids are hydrochloric acid (molecular weight: 36, pKa: -7) and hydrobromic acid (molecular weight: 81, pKa:-). 9), hydroiodic acid (molecular weight: 128, pKa: -10), sulfuric acid (molecular weight: 98, pKa: -10), nitric acid (molecular weight: 63, pKa: -1.5), perchloric acid (molecular weight: -1.5). 100, pKa: -10), tetrafluoroboric acid (molecular weight: 88, pKa: -4.9), hexafluorophosphate (molecular weight: 146, pKa: -20), trifluoroacetic acid (molecular weight: 114, pKa :: 0.2), methanesulfonic acid (molecular weight: 96, pKa: -1.9), paratoluenesulfonic acid (molecular weight: 172, pKa = -2.8), trifluoromethanesulfonic acid (molecular weight: 150, pKa:- 13), camphorsulfonic acid (molecular weight: 232, pKa: −1.2) and the like.

When the cationic group of the cationic organic polymer (c) forms a salt, the method of forming the salt with the acidic compound is, for example, the amino group contained in the cationic organic polymer (c) and the electrophoretic reagent { It may be reacted with an organic halide (methyl chloride, ethyl chloride, methyl bromide, ethyl bromide, etc.), dialkyl carbonate (dimethyl carbonate, diethyl carbonate, etc.) and sulfuric acid ester (dimethyl sulfate, diethyl sulfate, etc.)}. , Amino group or Ammonio group may be neutralized with an acidic compound. The formation of the salt can also be polymerized by using a monomer having an amino group or an ammonio group as a salt.
The reaction between the amino group and the electrophilic reagent can be carried out by mixing the amino group-containing monomer or polymer with the electrophobic reagent in the presence of water or any solvent and heating as necessary. Alternatively, neutralization of the ammonio group with an acidic compound can be carried out by mixing the amino or ammonio group-containing monomer or polymer with the acidic compound in the presence of water or any solvent.

As the cationic organic polymer (c), a polymer having an ammonio group is preferable from the viewpoint of enhancing the liquid permeability of the water-absorbent resin particles, and the ammonio group is more preferably a salt with a conjugate base of a strong acid, and the molecular weight is more preferable. It is particularly preferably a salt with a conjugate base of 30-300 strong acids.

The water-absorbent resin particles can be obtained by mixing the crosslinked polymer (A) and the cationic organic polymer (c). As a mixing method of the cationic organic polymer (c), a cylindrical mixer, a screw type mixer, a screw type extruder, a turbulizer, a Nauter type mixer, a double arm type kneader, a fluid type mixer, and a V type mixing are used. Examples thereof include a method of uniformly mixing using a known mixing device such as a machine, a minced mixer, a ribbon type mixer, an air flow type mixer, a rotary disk type mixer, a conical blender and a roll mixer.

For mixing the crosslinked polymer (A) and the cationic organic polymer (c), it is preferable to add the cationic organic polymer (c) to the crosslinked polymer (A) under stirring. The cationic organic polymer (c) to be added may be added at the same time as water and / or a solvent.
When the cationic organic polymer (c) is added at the same time as water and / or a solvent, a solution in which the cationic organic polymer (c) is dissolved in water and / or a solvent or a cationic organic polymer (c) is added to water and / or a solvent. It is preferable to add the dispersion dispersed in the water, and it is more preferable to add the dispersion from the viewpoint of workability and the like. When adding a solution or dispersion, it is preferable to add by spraying or dropping.

When an aqueous solution in which the cationic organic polymer (c) is dissolved in water is used, the content of the cationic organic polymer (c) contained in the aqueous solution is preferably 5 to 70% by weight based on the total weight of the aqueous solution. It is preferably 10 to 60% by weight.

As the aqueous solution obtained by dissolving the cationic organic polymer (c) in water, an aqueous solution obtained after polymerizing the above-mentioned monomer composition in water may be used, and the cationic organic polymer (c) may be used, for example, by an impeller type. An aqueous solution obtained by dissolving in water by a method such as a method of dissolving in water using a mixing container equipped with a stirrer may be used.
The aqueous solution may contain an additive such as an arbitrary stabilizer, if necessary. Examples of the stabilizer include commercially available chelating agents [diethylenetriamine (salt), triethylenetetramine (salt), ethylenediaminetetraacetic acid (salt), citric acid (salt), tartrate acid (salt), malic acid (salt), etc.]. , Commercially available inorganic reducing agents [sulfuric acid (salt), hydrogen sulfite (salt), phosphite (salt) and hypophosphite (salt), etc.], commercially available pH adjusters [phosphate (salt), boric acid ( Salt), alkali metal (salt) and alkaline earth metal (salt), etc.], commercially available antioxidants [vitamin C (ascorbic acid), vitamin E (tocopherol), dibutyl hydroxytoluene (also called BHT), butyl hydroxyanisole (Also also referred to as BHA), sodium erythorbate, propyl desalted acid, sodium sulfite, etc.].

The temperature at which the crosslinked polymer (A) and the cationic organic polymer (c) are mixed is not particularly limited, but is preferably 10 to 150 ° C, more preferably 20 to 100 ° C, and particularly preferably 25 to 80 ° C. ..

After mixing the crosslinked polymer (A) and the cationic organic polymer (c), further heat treatment may be performed. The heating temperature is preferably 25 to 180 ° C., more preferably 30 to 175 ° C., and particularly preferably 35 to 170 ° C. from the viewpoint of fracture resistance of the resin particles. Indirect heating using steam is possible if the heating is 180 ° C or lower, which is advantageous in terms of equipment. Further, when the heating is not performed, the water and the solvent used in combination may remain excessively in the water-absorbent resin, and the absorption performance may be deteriorated.
When heating is performed after mixing the crosslinked polymer (A) and the cationic organic polymer (c), the heating time can be appropriately set depending on the heating temperature, but from the viewpoint of absorption performance, it is preferably 5 to 60 minutes, further. It is preferably 10 to 40 minutes. The water-absorbent resin obtained by mixing the crosslinked polymer (A) and the cationic organic polymer (c) is further surface-treated with a cationic organic polymer of the same kind or different from the first used cationic organic polymer. It is also possible to do.

The content of the cationic organic polymer (c) in the water-absorbent resin particles (P) can be adjusted according to the use of the water-absorbent resin particles, but the crosslinked polymer (A) and the cationic organic polymer (c) can be adjusted. ), It is preferably 0.01 to 5% by weight, more preferably 0.1 to 3% by weight. Within this range, the water-absorbent resin particles have good liquid permeability and shape retention, which is more preferable.

The surface of the water-absorbent resin particles (P) can be further coated with an inorganic powder. Examples of this preferred inorganic powder include glass, silica gel, silica sol, silica, clay, carbon fiber, kaolin, talc, mica, bentonite, sericite, asbestos and silas). Of the inorganic powders, silica sol, silica and talc are preferred.

The shape of the inorganic powder may be amorphous (crushed), spherical, film-shaped, rod-shaped, fibrous or the like, but amorphous (crushed) or spherical is preferable, and spherical is more preferable. ..

The content (% by weight) of the inorganic powder is preferably 0.01 to 3.0, more preferably 0.05 to 1.0, and then preferably 0., based on the weight of the crosslinked polymer (A). It is 07 to 0.8, particularly preferably 0.10 to 0.6, and most preferably 0.15 to 0.5. Within this range, the anti-fog resistance of the absorbent article becomes even better.

The water-absorbent resin particles (P) include other additives {for example, known (for example, JP-A-2003-225565, JP-A-2006-131767, etc.) preservatives, fungicides, antibacterial agents, antioxidants, ultraviolet rays. It can also contain absorbents, colorants, fragrances, deodorants, organic fibrous materials, etc.}. When these additives are contained, the content (% by weight) of the additives is preferably 0.001 to 10, more preferably 0.01 to 5, particularly preferably 0.01 to 5, based on the weight of the crosslinked polymer (A). It is preferably 0.05 to 1, most preferably 0.1 to 0.5.

The water-absorbent resin particles (P) may be crosslinked polymer particles that absorb 40 times their own weight of physiological saline in 40 to 150 seconds, more preferably 55 to 120 seconds, and particularly preferably 65 to 110 seconds. preferable. Within this range, the anti-fog resistance of the absorbent article becomes even better. By adjusting the content of the hydrophobic substance (g), the average particle size of the crosslinked polymer, and the apparent density within the above-mentioned preferable ranges, the absorption time of the physiological saline can be adjusted within the preferable range, and the crosslinked polymer particles (A) can be adjusted. By adjusting the apparent density of the particles, the weight average particle size of the crosslinked polymer particles, and the like to the above-mentioned preferable ranges, it can be adjusted to a more preferable range. The absorption time of the physiological saline solution is the time measured by the following method in a room at 25 ± 2 ° C. and a humidity of 50 ± 10%. The temperature of the physiological saline solution to be used is adjusted in advance to 25 ° C ± 2 ° C before use.

<Measurement of absorption time of saline>
Place 1.00 g of the measurement sample in a 100 ml beaker and add 40 g of physiological saline (salt concentration 0.9% by weight). The mixture is allowed to stand without stirring, and the time until the physiological saline solution is completely absorbed (the beaker is slightly tilted at the end of water absorption to check the liquid residue) is measured and used as the absorption time (t1). The temperature of the physiological saline used and the measurement atmosphere shall be 25 ° C ± 2 ° C.

The water retention amount (g / g) of the water-absorbent resin particles (P) is preferably 25 to 60, more preferably 26 to 55, and particularly preferably 27 to 50, from the viewpoint of the antifogging resistance of the absorbent article. The amount of water retained in the crosslinked polymer particles is measured by the following method.

<Measurement method of water retention amount of water-absorbent resin particles (P)>
Put 1.00 g of the measurement sample in a tea bag (length 20 cm, width 10 cm) made of a nylon net with an opening of 63 μm (JIS Z8801-1: 2006), and put 1,000 ml of physiological saline (salt concentration 0.9% by weight). Immerse in it for 1 hour without stirring, then hang it for 15 minutes to drain it. Then, the tea bag is placed in a centrifuge, dehydrated at 150 G for 90 seconds to remove excess physiological saline, the weight (h1) including the tea bag is measured, and the water retention amount is calculated from the following formula.
Water retention (g / g) = (h1)-(h2)
The temperature of the physiological saline used and the measurement atmosphere shall be 25 ° C ± 2 ° C.
The weight of the tea bag after centrifugal dehydration is measured in the same manner as above except that the measurement sample is not used (h2).

The gel elastic modulus (N / m ² ) of the 30-fold swelling gel obtained by absorbing 30 parts by weight of artificial urine by 1 part by weight of the water-absorbent resin particles (P) is preferably 2,000 to 3,000, more preferably 2,000 to 3,000. Is 2,025 to 2,950, particularly preferably 2,050 to 2,900, and most preferably 2,075 to 2,850. Within this range, when the absorbent resin particles (P) of the present invention are applied to an absorbent article, further excellent leakage resistance is exhibited. The gel elastic modulus (N / m ² ) is a value obtained by the following measuring method.

<Measurement method of gel elastic modulus>
Artificial urine [200 parts by weight of urea, 80 parts by weight of sodium chloride, 8 parts by weight of magnesium sulfate (7-hydrate), 3 parts by weight of calcium chloride (dihydrate), 2 parts by weight of ferric sulfate (7-hydrate), ion 9704 parts by weight of exchanged water] Weigh 60.0 g into a 100 ml beaker (inner diameter 5 cm), weigh 2.0 g of the measurement sample in the same manner as described in JIS K7224-1996, and put it into the beaker. Create a 30-fold swelling gel. To prevent the swelling gel from drying, wrap it in a beaker containing a 30-fold swelling gel, and leave the beaker in an atmosphere of 40 ± 2 ° C for 3 hours and then in an atmosphere of 25 ± 2 ° C for 0.5 hours. After that, the wrap is removed, and the gel elasticity of the 30-fold swelling gel is measured using a card meter (for example, Card Meter Max ME-500 manufactured by Aitec Techno Engineering Co., Ltd.). The conditions of the card meter are as follows.
・ Pressure sensitive shaft: 8mm
・ Spring: for 100g ・ Load: 100g
・ Rising speed: 1 inch / 7 seconds ・ Test properties: Breaking ・ Measurement time: 6 seconds ・ Measurement atmosphere temperature: 25 ± 2 ° C

In the absorbent body of the absorbent article of the present invention, the liquid diffusion member (B) is a member for diffusing the absorbed liquid, and examples thereof include hydrophilic fibers and synthetic fibers. As hydrophilic fibers, various fluff pulps, cotton-like pulps, and other hydrophilic fibers that have been conventionally used in absorbent articles {raw materials (conifers, broadleaf trees, etc.), manufacturing methods [chemical pulps, semi-chemical pulps, and chemithermomechanicals]. Pulp (CTMP), etc.], the bleaching method is not particularly limited}, and the form is not particularly limited, such as a sheet-like material such as tissue. Further, the synthetic fiber can be used alone or in combination with the above-mentioned fluff pulp, cotton-like pulp and the like, and may be in the form of a non-woven fabric sheet. Examples of the synthetic fiber include polyolefin fiber (polyethylene fiber, polypropylene fiber, etc.), polyester fiber (polyethylene terephthalate fiber, etc.), polyolefin / polyester composite fiber, polyamide fiber, polyacrylonitrile fiber, and the like.

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

In the absorbent body of the absorbent article of the present invention, the water-absorbent resin particles (P) and the liquid diffusion member (B) may be uniformly mixed, or one of them may be unevenly distributed.
The absorber is composed of water-absorbent resin particles (P) and hydrophilic fibers or synthetic fibers which are liquid diffusion members (B), and (1) hydrophilicity composed of pulp or the like arranged in layers. A form in which water-absorbent resin particles (P) are dispersed between layers of fibers or synthetic fibers; (2) hydrophilic fibers made of pulp, heat-sealing fibers, etc., synthetic fibers and water-absorbent resin particles (P) Mixed form; (3) Two or more sheets of water-absorbent paper or a non-woven fabric, and if necessary, a form in which water-absorbent resin particles (P) are sandwiched together with hydrophilic fibers can be mentioned. Further, the diffusible member (B) may be used as a surface sheet on the uppermost surface of the absorber.

The amount of the water-absorbent resin particles (P) of the present invention added to the absorber can be variously varied depending on the type and size of the absorber and the target absorption performance, and is 10 based on the weight of the absorber. It is preferably ~ 95% by weight, more preferably 30 to 95% by weight, and particularly preferably 50 to 95% by weight. Within this range, the absorptive capacity of the obtained absorber tends to be further improved.

In order to improve the shape retention before and during the use of the absorber, the fibers may be adhered to each other by adding an adhesive binder. Examples of such adhesive binders include heat-fusing synthetic fibers, hot melt adhesives, adhesive emulsions and the like.

Examples of the heat-bondable synthetic fiber include a total fusion type binder such as polyethylene, polypropylene, and an ethylene-propylene copolymer, and a non-total fusion type binder having a side-by-side or core-sheath structure of polypropylene and polyethylene. In the above-mentioned non-zen'yū type binder, only the polyethylene portion is heat-sealed.

Hot melt adhesives include base polymers such as ethylene-vinyl acetate copolymer, styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, and amorphous polypropylene, as well as tackifiers, plasticizers, and antioxidants. And so on.

Adhesive emulsions include, for example, polymers of at least one monomer selected from the group consisting of methyl methacrylate, styrene, acrylonitrile, 2-ethylhexyl acrylate, butyl acrylate, butadiene, ethylene, and vinyl acetate. Be done. These adhesive binders may be used alone or in combination of two or more.

In the present invention, the gel particle shape-retaining agent (C) is eluted by contact with the aqueous liquid and diffused together with the aqueous liquid. The water-absorbent resin particles that are in contact with the aqueous liquid in which the shape-retaining agent is eluted absorb water and become gel particles, and the shape-retaining agent adheres to the surface of the gel particles, which has the effect of increasing the adhesive strength between the gel particles. It is expected to have excellent shape retention. From the viewpoint of elution property, the gel particle shape-retaining agent (C) preferably has a solubility in water (25 ° C.) of 5 g or more / 100 g of water.

In the present invention, the gel particle shape-retaining agent (C) has _two -NH groups and _two -NH monoalkyl (1 to 4 carbon atoms) substituents (that is, one of the _two hydrogen atoms of -NH is an alkyl group. At least one amino selected from the group consisting of a substituted group) and a -NH ₂ dialkyl (1 to 4 carbon atoms) substituent (ie, a group in which two hydrogen atoms of -NH ₂ are substituted with an alkyl group). It is a cationic organic polymer (c2) having a cationic group which is a salt of a group (am) (substituated or unsubstituted -NH ₂ groups are also simply referred to as amino groups (am) below).

Specific examples of the amino group (am) include _-NH2 group, methylamino group, ethylamino group, propylamino group, n-butylamino group, 1-methylpropylamino group and 2-methylpropylamino group. Groups, tertiary butylamino groups, dimethylamino groups, diethylamino groups, dibutylamino groups and the like can be mentioned.
Examples of the salt of the amino group (am) include a group obtained by neutralizing the amino group (am) with an acid (preferably Lewis acid and Bronsted acid).

Among the acids that neutralize the amino group (am), examples of Lewis acid include halogenated typical element compounds such as boron trifluoride and aluminum chloride, and typical element-containing trifrates such as scandium trifurate, and Bren. Examples of the stead acid include an inorganic acid and an organic acid.
Inorganic acids include oxo acids (perchloric acid, nitric acid, sulfuric acid, phosphoric acid, tetrafluoroboric acid, hexafluorophosphate and boric acid, etc.) and hydrogen halides (hydrogen fluoride, hydrochloride, hydrobromic acid, etc.). And hydrogen cyanide, etc.), and examples of the organic acid include organic carboxylic acids (acetic acid, trifluoroacetic acid, etc.) and organic sulfonic acids {aliphatic sulfonic acid (methanesulfonic acid, trifluoromethanesulfonic acid, etc.), alicyclic type. Examples thereof include sulfonic acid (camper sulfonic acid, etc.) and aromatic sulfonic acid (paratoluene sulfonic acid, etc.)}. Of these, Bronsted acid is preferable.

The acid that neutralizes the amino group (am) is preferably a strong acid having a molecular weight of 30 to 300, and preferably a strong acid having a molecular weight of 35 to 200. In the present invention, the strong acid means an acid having a pKa of 1 or less (preferably 0 or less) (aqueous solution, 25 ° C.).

As the strong acid, the above-mentioned strong acid can be preferably mentioned, and hydrochloric acid (molecular weight: 36, pKa: -7), sulfuric acid (molecular weight: 98, pKa: -10), methanesulfonic acid (molecular weight: 96, pKa:-) can be mentioned. 1.9) is more preferable.

The cationic organic polymer (c2) is a monomer composition containing the cationic monomer having the amino group (am) and / or the cationic monomer having the salt of the amino group (am) as an essential component. A polymer or a salt thereof. The cationic organic polymer (c2) may be a polymer of a monomer composition or a salt of a polymer of the monomer composition as long as it has a cationic group which is a salt of the amino group (am). May be. For example, when the monomer composition is a monomer composition containing a cationic monomer having a salt of the amino group (am) as an essential component, the polymer (c2) is the monomer composition. On the other hand, when the monomer composition is a monomer composition containing a cationic monomer having an amino group (am) as an essential component, the polymer (c2) is this polymer. It may be a salt of a polymer of the monomeric composition. Further, for example, the monomer composition is a monomer composition containing a cationic monomer having an amino group (am) and a cationic monomer having a salt of an amino group (am) as components. In some cases, the polymer (c2) may be a polymer of this monomeric composition or a salt thereof. The cationic group of the polymer (c2) is a salt thereof if the cationic monomer has the amino group (am), and / or the salt of the amino group (am) in which the cationic monomer has the amino group (am). If it has, it is the salt.

Examples of the cationic monomer include a -NH ₂ group-containing group (for example, an aminoalkyl (1 to 4 carbon atoms) group) and a -NH ₂ group monoalkyl (1 to 4 carbon atoms) substituent (for example, 1 to 4 carbon atoms). Alkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) group and dialkyl (1 to 4 carbon atoms) substituent (for example, dialkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) Examples thereof include a cationic monomer having at least one amino group (am) selected from the group consisting of a group (group), and more specifically, for example, an amino group (am) -containing (meth) acrylate and an amino group (am). ) Containing (meth) acrylic acid amide, amino group (am) -containing vinyl compound and the like can be mentioned.
Examples of the amino group (am) -containing (meth) acrylate include aminoalkyl (1 to 4 carbon atoms) (meth) acrylate (aminoethyl (meth) acrylate, aminopropyl (meth) acrylate, etc.) and alkyl (1 to 4 carbon atoms). ) Aminoalkyl (1 to 4 carbon atoms) (meth) acrylate (methylaminoethyl (meth) acrylate, ethylaminoethyl (meth) acrylate, methylaminopropyl (meth) acrylate, ethylaminopropyl (meth) acrylate and tertiary butyl Aminoethyl (meth) acrylate, etc.) and dialkyl (1 to 4 carbon atoms) Aminoalkyl (1 to 4 carbon atoms) (meth) acrylate (dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dibutylaminoethyl ( Examples thereof include (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, dibutylaminopropyl (meth) acrylate, etc.), and examples of the amino group (am) -containing (meth) acrylamide include aminoalkyl (carbon). Numbers 1 to 4) (meth) acrylamide (aminoethyl (meth) acrylamide, aminopropyl (meth) acrylamide, etc.), alkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide (methylamino) Ethyl (meth) acrylamide, ethylaminoethyl (meth) acrylamide, methylaminopropyl (meth) acrylamide, ethylaminopropyl (meth) acrylamide, tertiary butylaminoethyl (meth) acrylamide, etc.) and dialkyl (1 to 4 carbon atoms) Aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide (dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dibutylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) Acrylamide, dibutylaminopropyl (meth) acrylamide, etc.) and the like, and examples of the amino group (am) -containing vinyl compound include p-aminostyrene, 2-vinylpyridine, vinylaniline, and (meth) allylamine.
These cationic monomers may be used alone or in combination of two or more.

As the cationic monomer, among the above-mentioned amino group (am) -containing (meth) acrylate and the above-mentioned amino group (am) -containing (meth) acrylamide, aminoalkyl (carbons 1 to 4) (meth) Acrylic, Alkyl (1 to 4 carbon atoms) Aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, Dialkyl (1 to 4 carbon atoms) Aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, Aminoalkyl (carbon) Numbers 1 to 4) (meth) acrylamide, alkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide and dialkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) ( Meta) acrylamide is preferred, and aminoethyl (meth) acrylate and N, N-dimethylaminoethyl (meth) acrylate are even more preferred.

The cationic organic polymer (c2) consists of a group consisting of ₂ -NH groups, ₂ monoalkyl (1 to 4 carbon atoms) substituents of -NH and ₂ dialkyl (1 to 4 carbon atoms) substituents of -NH. When a monomer composition containing a cationic monomer having a salt of at least one selected amino group (am) as an essential constituent is polymerized, the cationic monomer is the above-mentioned amino group. Examples thereof include salts of the monomers having (am), and examples thereof include salts in which the cationic monomer having the amino group (am) is neutralized with the Lewis acid or the Bronsted acid.

Examples of the monomer constituting the monomer composition together with the cationic monomer include the water-soluble vinyl monomer (a1), the other copolymerizable vinyl monomer (a3), and the hydrolyzable. The same as the vinyl monomer (a2) can be mentioned, and among them, (meth) acrylic acid (salt) and (meth) acrylamide are preferable.

The proportion of the cationic monomer contained in the monomer composition which is a raw material of the cationic organic polymer (c2) is 50 mol based on the total number of moles of the monomers contained in the monomer composition. % Or more, preferably 60 mol% or more from the viewpoint of blocking resistance of the water-absorbent resin.

The cationic organic polymer (c2) is a known polymerization of a monomer composition containing a cationic monomer having an amino group (am) and / or a cationic monomer having a salt of an amino group (am). In addition to being obtained by polymerization by a method, it can also be obtained from the market as a polymer flocculant and a dye fixing agent.
Known methods for polymerizing a monomer composition containing a cationic monomer include an emulsion polymerization method using an organic solvent and / or water, a suspension polymerization method, and a solution polymerization method, among which an aqueous solution is used. In the case of the polymerization method, an aqueous solution of a monomer composition having a monomer concentration of usually 10 to 80% by weight is subjected to a known polymerization catalyst {for example, persulfates such as ammonium persulfate and potassium persulfate under an inert gas atmosphere. Organic peroxides such as benzoyl peroxide; azo compounds such as 2,2'-azobis (amidinopropane) hydrochloride, azobiscyanovaleric _acid ; peroxides such as redox catalyst ₍ H2O2 and potassium persulfate). A method of polymerizing at about 20 to 100 ° C. for several hours by adding a compound and a reducing agent such as sodium bisulfite and ferrous sulfate) etc. can be mentioned.

When the monomer composition contains a cationic monomer having an amino group (am) as a cationic monomer, the cationic organic polymer (c2) is obtained by polymerizing the monomer composition. The polymer can be obtained by further neutralizing the polymer with the Lewis acid or the Bronsted acid.
Neutralization with Lewis acid or Bronsted acid can be performed by mixing the polymer obtained by polymerizing the monomer composition by the above method and the acid by a known method, and the polymer and the acid can be used. It is preferable to mix with and in an aqueous solution containing a polymer.

The cationic organic polymer (c2) preferably has a structural unit represented by the following general formula (1).

In the general formula (1), R ¹ and R ² are the same or different, and are hydrogen atoms or alkyl groups having 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group and a tertiary butyl group. However, a hydrogen atom or a methyl group is preferable from the viewpoint of absorption performance and the like. R ³ is a hydrogen atom or a methyl group, and a methyl group is preferable from the viewpoint of the polymerizable property of the monomer composition.

Q is an alkylene group having 1 to 4 carbon atoms, and examples thereof include a methylene group, an ethylene group, a 1,2-propylene group, a 1,3-propylene group and a 1,4-butylene, and polymerization of a monomer composition. An ethylene group is preferable from the viewpoint of properties and the like.
X is an oxygen atom or an imino group, preferably an oxygen atom.
Z ⁻ represents a conjugate base of Bronsted acid, and examples of the Bronsted acid include the same Bronsted acid as described above, and preferred ones are also the same.

The structural unit represented by the general formula (1) is the above-mentioned aminoalkyl (carbon number 1 to 4) (meth) acrylate, alkyl (carbon number 1 to 4) aminoalkyl (carbon number 1 to 4) (meth) acrylate. , Dialkyl (1 to 4 carbon atoms) Aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, Aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide, Alkyl (1 to 4 carbon atoms) Aminoalkyl (carbon number 1 to 4) Structure derived from at least one cationic monomer selected from the group consisting of 1 to 4) (meth) acrylamide and dialkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide. It is a unit.

The cationic organic polymer (c2) having a structural unit represented by the general formula (1) is the above-mentioned aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, alkyl (1 to 4 carbon atoms) aminoalkyl (carbon). Numbers 1 to 4) (meth) acrylate, dialkyl (number of carbons 1 to 4) aminoalkyl (number of carbons 1 to 4) (meth) acrylate, aminoalkyl (number of carbons 1 to 4) (meth) acrylamide, alkyl (number of carbons) 1 to 4) At least one selected from the group consisting of aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide and dialkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide. A method for polymerizing a monomer composition containing a cationic monomer, the above-mentioned aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, alkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms). (Meta) acrylate, dialkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide, alkyl (1 to 4 carbon atoms) amino At least one cationic monomer selected from the group consisting of alkyl (1 to 4 carbon atoms) (meth) acrylamide and dialkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide. A method for polymerizing a monomer composition containing a neutralizing salt of Brenstead acid or the above-mentioned aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, alkyl (1 to 4 carbon atoms) aminoalkyl (carbon number of carbon atoms). 1 to 4) (meth) acrylate, dialkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide, alkyl (1 carbon number) ~ 4) At least one cation selected from the group consisting of aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide and dialkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide. It can be obtained by a method of further neutralizing a polymer obtained by polymerizing a monomer composition containing a sex monomer with Bronsted acid or the like.

The cationic organic polymer (c2) preferably has a number average molecular weight of 10,000 or more, more preferably 15,000 to 5,000,000, still more preferably 30,000 to 4,000,000, and even more preferably 5. It is 10,000 to 1,000,000, most preferably 400,000 to 950,000. If the number average molecular weight is less than 10,000, the liquid permeability of the water-absorbent resin particles and the blocking property of the gel may deteriorate. The number average molecular weight of the cationic organic polymer (c2) is, for example, manufactured by gel permeation chromatography (Agileant Technology Co., Ltd.) equipped with a multi-angle light scattering detector (DAWN HELEOS II manufactured by Shoko Scientific Co., Ltd.). , 1200 series) (hereinafter abbreviated as GPC-MALS) was used, an aqueous solution containing 0.5 M acetic acid and 0.2 M sodium nitrate was used as a solvent, the sample concentration was 0.2% by weight, and the column stationary phase was used. Uses a polymer-based filler (OHpak SB-806M HQ manufactured by Shoko Scientific Co., Ltd.), and the column temperature is measured at 40 ° C. This measurement condition is given as an example, and is not limited to this.

The content of the gel particle shape-retaining agent (C) is preferably 0.01 to 5% by weight with respect to the weight of the water-absorbent resin particles (P) from the viewpoint of shape retention and repeated liquid absorption rate. It is more preferably 0.05 to 3% by weight, and most preferably 0.1 to 1% by weight.

The absorber in the absorbent article of the present invention preferably contains the gel particle shape-retaining agent (C) in a portion through which the liquid passes, for example, a portion in which the liquid diffusible member (B) is present. The gel particle shape-retaining agent (C) may be in contact with the water-absorbent resin particles (P) at the time of water absorption, and may not be present on the surface of the resin particles before water absorption. From the viewpoint of shape retention, the gel particle shape-retaining agent (C) is preferably contained in the absorber before water absorption, and is applied to tissues, non-woven fabrics, water-absorbent resin particles, hydrophilic fibers, and synthetic fibers. It is more preferable to keep it.

For example, the gel particle shape-retaining agent (C) can be mixed with the liquid-diffusing member (B) to obtain a liquid-diffusing member (B) containing the gel particle shape-retaining agent (C). It is preferably obtained by contacting the gel particle shape-retaining agent (C) -containing aqueous solution with the liquid diffusible member (B) and then removing the water. By mixing the gel particle shape-retaining agent (C) in this way, the gel particle shape-retaining agent (C) is incorporated into the surface or the inside of the liquid diffusible member (B). It is preferable that at least the surface of the liquid diffusible member (B) is adhered, and more preferably, most of the liquid diffusible member (B) is attached to the surface.

For mixing the liquid diffusible member (B) and the gel particle shape retaining agent (C), an aqueous solution or dispersion containing the gel particle shape retaining agent (C) is dropped, applied, sprayed, etc. on the surface of the liquid diffusible member (B). How to do it, etc. The gel particle shape-retaining agent (C) may be added at the same time as water and / or a solvent.
When the gel particle shape-retaining agent (C) is added at the same time as water and / or a solvent, a solution in which the cationic organic polymer (c2) is dissolved in water and / or a solvent or a cationic organic polymer (c2) is added in water and / or. It is preferable to add the dispersion dispersed in the solvent, and it is more preferable to add the dispersion from the viewpoint of workability and the like. When adding a solution or dispersion, it is preferable to add by spraying or dropping.

When the cationic organic polymer (c2) is added as a dispersion, it is a dispersion in oil in which the cationic organic polymer (c2) is dispersed in a hydrophobic solvent in that blocking of the water-absorbent resin composition can be suppressed. Is preferable.
When the cationic organic polymer (c2) is a dispersion in oil dispersed in a hydrophobic solvent, the content of the cationic organic polymer (c2) contained in the dispersion is the hydrophobic solvent and the cationic organic polymer (c2). It is preferably 5 to 70% by weight, more preferably 10 to 60% by weight, based on the total weight of the dispersion containing the above.
The dispersed particle size of the cationic organic polymer (c2) dispersed in the hydrophobic solvent preferably has a volume average particle size of 0.1 nm to 1 mm, more preferably 1 nm to 100 μm. The volume average particle size of the cationic organic polymer (c2) is determined by, for example, a dynamic light scattering method using a laser diffraction / scattering type particle size distribution measuring device (for example, LA-950 and SZ-100; both manufactured by HORIBA, Ltd.). Be measured.

The dispersion of the cationic organic polymer (c2) in oil using a hydrophobic solvent is a method of mechanically mixing the cationic organic polymer (c2) in a dispersion medium using a known disperser such as a homogenizer and a dissolver. It can be carried out by a known method such as a method of emulsion polymerization or suspension polymerization of a monomer which is a constituent component of the cationic organic polymer (c2) in a dispersion medium.
The dispersion may contain any dispersant and additives such as stabilizers, if necessary.

The method for bringing the liquid diffusible member (B) into contact with the gel particle shape-retaining agent (C) -containing aqueous solution is not particularly limited. A method of immersing the liquid diffusible member (B) in the gel particle shape-retaining agent (C) -containing aqueous solution, or dropping, applying, spraying, etc. the gel particle shape-retaining agent (C) -containing aqueous solution on the surface of the liquid diffusible member (B). The method and the like can be mentioned. Thus, it is preferable to apply or spray the gel particle shape-retaining agent (C) on the surface of the liquid diffusion member (B) in advance before forming the absorber. As a method for constructing the absorber, a known method can be used. For example, the absorber can be manufactured by a known manufacturing method (Japanese Patent Laid-Open Nos. 2013-255565, 2014-233447, 2003-225565). No., JP-A-2006-131767, JP-A-2005-097569, etc.).

The concentration of the gel particle shape-retaining agent (C) in the gel particle shape-retaining agent (C) -containing aqueous solution is preferably 0.01 to 50% by mass, more preferably 0.1 to 35% by mass, and further preferably 0.2. ~ 25. In the case of immersion, the lower the solution concentration, the easier it is to add, and in the case of coating or spraying, the higher the solution concentration is, from the viewpoint of shortening the drying time.

In the present invention, the content of the gel particle shape-retaining agent (C) is preferably 0.05 to 20% by mass, more preferably 0.05 to 20% by mass, based on the total weight of the liquid diffusion member (B), from the viewpoint of shape retention and absorption performance. It is preferably 0.5 to 15% by mass, and particularly preferably 2 to 10% by mass.

Water when contacted as an aqueous solution may be removed, or may be used as it is without being removed. The method for removing water is not particularly limited. For example, there is a method in which an appropriate amount of the gel particle shape-retaining agent (C) of the present invention is brought into contact with the liquid diffusible member (B), followed by squeezing, centrifugal dehydration, heating, and drying to remove water. The heating temperature is preferably 15 to 80 ° C, more preferably 20 to 60 ° C. From the viewpoint of suppressing coloration, the heating and drying time is preferably 15 minutes or more by blowing air at a temperature close to room temperature, and more preferably 1 hour or more. If the drying time is 1 hour or more, it will be in a dry state to the extent that there is no problem in actual use.

In the absorbent article of the present invention, since the absorber contains the gel particle shape-retaining agent (C) during absorption of an aqueous liquid, the absorbent resin particles are characterized by excellent shape retention. Due to its excellent shape retention, the absorber has excellent shape retention even when an external force is applied, and even if a constant force is continuously or discontinuously applied to the absorption site, the absorption part may be torn or twisted. It is possible to suppress liquid leakage and the accompanying skin rash.

The absorber in the absorbent article of the present invention exhibits a silky feel even when it absorbs a liquid to be absorbed (body fluid such as sweat and urine, and water such as seawater, groundwater and muddy water). When this absorber is applied to sanitary products such as disposable diapers, it has excellent shape retention even when external force is applied after absorption, and absorbs even if a constant force is continuously or discontinuously applied to the absorber. The body does not tear or twist, there is little liquid leakage due to a decrease in absorption capacity, and it is unlikely to cause skin irritation. Therefore, an absorbent article exhibiting high absorption performance can be easily manufactured.

As the absorbent article, an absorbent article provided with an absorbent body and a breathable back sheet is preferable, and an absorbent article as a hygienic article is more preferable. Examples of hygienic products include paper diapers (children's paper diapers, adult paper diapers, etc.), paper towels, pads (pads for incontinence, surgical underpads, etc.), pet sheets (pet urine absorption sheets, etc.) and the like. Of these hygienic items, disposable diapers are more suitable. As the constitution and manufacturing method of these absorbent articles, known ones can be applied.

For example, by combining the above-mentioned absorber and the impermeable sheet, an absorbent article such as a disposable paper diaper can be formed.

Examples of the material of the impermeable sheet include a synthetic resin film made of polyethylene, polypropylene, ethylene vinyl acetate, polyvinyl chloride and the like, a film made of a composite material of these synthetic resins and a non-woven fabric, and the above-mentioned synthetic resin. Examples thereof include a film made of a composite material of and woven fabric. This impermeable sheet may have the property of allowing vapor to pass through.

The absorbent article of the present invention is not limited to the above-mentioned hygiene products, but is also used as a pet urine absorbent, a urine gelling agent for portable toilets, a freshness-preserving agent for fruits and vegetables, a drip absorbent for meat and seafood, and an ice pack. , Disposable body warmers, gelling agents for batteries, water retention agents for plants and soil, dew condensation prevention agents, water blocking materials and packing materials, artificial snow, and the like.

Hereinafter, the present invention will be further described with reference to Examples, but the present invention is not limited thereto. Hereinafter, unless otherwise specified,% indicates weight% and parts indicate parts by weight.

<Production example of crosslinked polymer particles>
<Manufacturing example 1>
Water-soluble vinyl monomer (a1) {acrylic acid} 155 parts (2.15 mol parts), cross-linking agent (b) {pentaerythritol triallyl ether} 0.6225 parts (0.0024 mol parts) and deionized water 340. Twenty-seven parts were kept at 3 ° C. while stirring and mixing. After inflowing nitrogen into this mixture to reduce the amount of dissolved oxygen to 1 ppm or less, 0.62 parts of a 1% hydrogen peroxide solution and 1.1625 parts of a 2% ascorbic acid aqueous solution and 2% of 2,2'-azobis [ 2-325 parts of 2-methyl-N- (2-hydroxyethyl) -propionamide] aqueous solution was added and mixed to initiate polymerization. After the temperature of the mixture reached 90 ° C., the mixture was polymerized at 90 ± 2 ° C. for about 5 hours to obtain a hydrogel (1).
Next, while shredding 502.27 parts of this hydrogel (1) with a mincing machine, 128.42 parts of a 48.5% sodium hydroxide aqueous solution was added and mixed, and then the hydrophobic substance (g) {Mg stearate was added. } 1.9 parts were added and mixed to obtain a shredded gel (2). Further, the shredded gel (2) was dried with a ventilation type band dryer {150 ° C., wind speed 2 m / sec} to obtain a dried product. The dried product was pulverized with a juicer mixer and then adjusted to a particle size of 150 to 710 μm using a sieve having a mesh size of 150, 300, 500, 600 and 710 μm to obtain dried product particles. While stirring 100 parts of the dried body particles at high speed, 5 parts of a 2% water / methanol mixed solution of ethylene glycol diglycidyl ether (water / methanol weight ratio = 70/30) is added while spraying and mixed, and 150 parts are mixed. It was allowed to stand at ° C. for 30 minutes and surface-crosslinked to obtain water-absorbent resin particles (P-1). The weight average particle diameter of the water-absorbent resin particles (P-1) was 400 μm, and the apparent density was 0.58 g / ml. The weight average particle size and the apparent density were measured by the following methods.

<Measurement of weight average particle size>
Standard sieves with openings of 1000 μm, 850 μm, 710 μm, 500 μm, 425 μm, 355 μm, 250 μm, 150 μm, 125 μm, 75 μm and 45 μm were stacked in order and combined on a saucer. About 50 g of water-absorbent resin particles were placed on the uppermost sieve and shaken with a low-tap test sieve shaker for 5 minutes. Weigh the particles remaining on each sieve and saucer, and calculate the weight fraction of the particles on each sieve with the total as 100% by weight. Particle size), the vertical axis is the weight fraction}, then a line connecting each point was drawn to obtain the particle size corresponding to the weight fraction of 50% by weight, and this was taken as the weight average particle diameter.

<Measurement of apparent density>
It was measured according to JIS K7365: 1999 in an environment of 25 ° C.

<Manufacturing example 2>
"Adjust to a particle size of 150 to 710 μm using a sieve with a mesh opening of 150, 300, 500, 600, 710 μm" is adjusted to a particle size of 150 to 500 μm using a sieve with a mesh opening of 150, 300, 500 μm. , A water-absorbent resin particles (P-2) were obtained in the same manner as in Production Example 1. The weight average particle diameter of the water-absorbent resin particles (P-2) measured in the same manner as in Production Example 1 was 300 μm, and the apparent density was 0.66 g / ml.

<Manufacturing example 3>
Water-absorbent resin particles (P-3) were obtained in the same manner as in Production Example 1 except that the hydrophobic substance (g) was not used. The weight average particle diameter of the water-absorbent resin particles (P-3) measured in the same manner as in Production Example 1 was 400 μm, and the apparent density was 0.64 g / ml.

<Manufacturing example 4>
145.4 parts of acrylic acid was diluted with 9.4 parts of water and neutralized by adding 242.3 parts of a 25% aqueous sodium hydroxide solution while cooling to 30 to 20 ° C. To this solution, 0.09 part of ethylene glycol diglycidyl ether, 0.0146 part of sodium hypophosphate monohydrate and 0.0727 part of potassium persulfate were added and dissolved, and a biomixer (Nippon Seiki Co., Ltd.) was added at 25 ° C. It was stirred and dispersed for 2 minutes with ABM-2 type manufactured by the same company to obtain an aqueous monomer solution.

Next, 624 parts of cyclohexane was placed in a reaction vessel equipped with a stirrer, a reflux cooler, a thermometer and a nitrogen gas introduction tube, and the polyoxyethylene octylphenyl ether phosphate ester (Daiichi Kogyo Seiyaku Co., Ltd., Commodity) was placed therein. Name: Plysurf A210G) After 1.56 parts were added and dissolved, nitrogen was replaced with stirring, and the temperature was raised to 70 ° C. Then, while keeping the temperature at 70 ° C., the aqueous monomer solution was added dropwise at 6.6 parts / minute for 6 minutes and held at 75 ° C. for 15 minutes, and then the remaining aqueous monomer solution was added at 6.6 parts / minute for 54 minutes. Dropped. Then, after aging at 75 ° C. for 30 minutes, the water content of the resin is about 20% by azeotropic boiling with cyclohexane (infrared moisture meter: FD-100 type, manufactured by Kett, measured at 180 ° C. for 20 minutes). It was removed until it became. When the mixture was cooled to 30 ° C. and stirring was stopped, the water-containing absorbent resin particles settled. Therefore, the absorbent resin particles and the cyclohexane layer were separated by decantation, separated by filtration, dried under reduced pressure at 80 ° C., and dried. Obtained particles. While stirring 100 parts of the dried body particles at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), 0.06 part of ethylene glycol diglycidyl ether as a surface cross-linking agent (d) and 0.42 parts of methanol were added. A mixed solution containing 0.18 parts of ion-exchanged water was added, and the mixture was uniformly mixed and then heated at 135 ° C. for 30 minutes to obtain surface-crosslinked water-absorbent resin particles (P-4). The weight average particle diameter of the water-absorbent resin particles (P-4) measured in the same manner as in Production Example 1 was 320 μm, and the apparent density was 0.50 g / ml.

<Manufacturing example 5>
A dispersion in oil of the cationic polymer (c2) was produced according to the method described in Japanese Patent Publication No. 54-37986. That is, 300 g of aminoethyl methacrylate methanesulfonate was dissolved in 200 g of ion-exchanged water to prepare a monomer aqueous solution. Separately, 430 g of IP solvent (isoparaffin manufactured by Idemitsu Kosan Co., Ltd.) was placed in 2 L corben, 70 g of polyoxyethylene sorbitan monostearate was dissolved, and the previously prepared monomer aqueous solution was emulsified and dispersed while continuing stirring. Nitrogen gas was passed through this emulsion for 30 minutes, and 3 mL of a 10 wt% acetone solution (catalyst solution) of azobisdimethylvaleronitrile was added while stirring at 50 ° C. on a water bath to initiate polymerization. After the reaction for 4 hours, 3 mL of the above catalytic solution was added, and the mixture was further stirred at 50 ° C. for 2 hours and then allowed to cool. The dispersion in oil of the cationic polymer (number average molecular weight 4 million, solid content concentration 30%) ) Was obtained. Let this dispersion in oil be (c2-1).

<Manufacturing example 6>
In Production Example 5, the same operation as in Production Example 5 was carried out except that the aminoethyl methacrylate methanesulfonate was changed to the aminoethyl methacrylate camphor sulfonate, and the dispersion of the cationic polymer in oil (number). An average molecular weight of 5 million and a solid content concentration of 30%) were obtained. Let this dispersion in oil be (c2-2).

<Manufacturing example 7>
An aqueous solution containing the cationic polymer (c2) was produced. That is, 50 parts of dimethylaminoethyl methacrylate / sulfate, 150 parts of ion-exchanged water, and 0.03 part of sodium hypophosphate monohydrate were added to a 500 mL separable flask and stirred well. After adding 1.5 parts of a 2% 2,2'-azobisamidinopropane dihydrochloride aqueous solution as an initiator while inflowing nitrogen into this mixture and substituting nitrogen in the reaction system, the temperature is 75 ° C. for 5 hours. The reaction was carried out to obtain an aqueous solution (solid content concentration 25%) containing a cationic organic polymer (c2-3). The number average molecular weight of the cationic organic polymer (c2-3) contained in the aqueous solution was 400,000.

<Reference manufacturing example 8>
In Production Example 7, the same operation as in Production Example 7 was performed except that the amount of sodium hypophosphite monohydrate used was changed from 0.03 part to 0.4 part, and the cationic organic polymer (c2- An aqueous solution containing 4) (solid content concentration 25%) was obtained. The number average molecular weight of the cationic organic polymer (c2-4) contained in the aqueous solution was 15,000.

<Manufacturing example 9>
In Production Example 7, the dimethylaminoethyl methacrylate / sulfate was changed to aminoethyl methacrylate / methanesulfonate, and 1.5 parts of the 2,2'-azobisamidinopropanedihydrochloride aqueous solution was changed to 1.0 part. The same operation as in Production Example 7 was carried out to obtain an aqueous solution (solid content concentration 25%) containing the cationic organic polymer (c2-5). The number average molecular weight of the cationic organic polymer (c2-5) contained in the aqueous solution was 950,000.

<Manufacturing example 10>
The cationic organic polymer obtained in Production Example 7 while stirring 100 parts of the water-absorbent resin particles (P-1) obtained in Production Example 1 at high speed (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm). 1.68 parts of an aqueous solution (solid content concentration 25%) containing c2-3) was added and uniformly mixed. It was heated at 80 ° C. for 30 minutes to obtain water-absorbent resin particles (P-5).

<Manufacturing example 11>
In Production Example 10, the water-absorbent resin particles (P-1) are changed to the water-absorbent resin particles (P-2), and the aqueous solution (solid content concentration 25%) containing the cationic organic polymer (c2-3) is 1. The same operation as in Production Example 10 was performed except that 68 parts were changed to 3.5 parts of the aqueous solution (solid content concentration 25%) containing the cationic organic polymer (c2-5) obtained in Production Example 9. Water-absorbent resin particles (P-6) were obtained.

<Manufacturing example 12>
In Production Example 10, 1.68 parts of an aqueous solution (solid content concentration 25%) containing a cationic organic polymer (c2-3) was added to the oil of the aminoethyl methacrylate methanesulfonate polymer prepared in Production Example 5. The same operation as in Production Example 10 was carried out except that the dispersion was changed to 3.0 parts of the dispersion (c2-1) to obtain water-absorbent resin particles (P-7).

<Manufacturing example 13>
In Production Example 10, 1.68 parts of an aqueous solution (solid content concentration 25%) containing a cationic organic polymer (c2-3) was added to the oil of the aminoethyl methacrylate camphor sulfonate polymer prepared in Production Example 6. The same operation as in Production Example 10 was performed except that the dispersion (c2-2) was changed to 3.0 parts. Water-absorbent resin particles (P-8) were obtained.

<Manufacturing Comparative Example 1>
The water-absorbent resin particles (P-1) obtained in Production Example 1 were used as they were as water-absorbent resin particles (R-1) for comparison.

<Manufacturing Comparative Example 2>
In Production Example 10, 1.68 parts of an aqueous solution (solid content concentration 25%) containing a cationic organic polymer (c2-3) was added to a polydiallyldimethylammonium chloride aqueous solution (manufactured by Senka Co., Ltd., molecular weight 950,000, solid content concentration 18%). ) The same operation as in Production Example 10 was carried out except for the change to 4.5 parts, and water-absorbent resin particles (R-2) for comparison were obtained.

Performance of the water-absorbent resin particles (P-1) to (P-8) of Production Examples 1 to 4, 10 to 13 and the water-absorbent resins (R-1) to (R-2) of Production Comparative Examples 1 to 2. As an evaluation result, the time to absorb 40 times the weight of the saline solution [physiological saline (40 times) absorption time], the amount of water retention and the gel elasticity were measured by the following methods, and together with the weight average particle size and the apparent density. It is described in Table 1.

<Measurement of saline (40 times) absorption time>
40 g of physiological saline (salt concentration 0.9% by weight) was added to each of the 100 ml beakers containing 1.00 g of the water-absorbent resin particles (P). After that, stand still without stirring, measure the time until the saline solution is completely absorbed (tilt the beaker a little at the end of water absorption to check the liquid residue), and absorb the saline solution (40 times). It was time. The physiological saline used and the temperature of the measurement atmosphere were 25 ° C ± 2 ° C.

<Measurement of water retention>
Put 1.00 g of water-absorbent resin particles (P) in a tea bag (length 20 cm, width 10 cm) made of a nylon net with a mesh opening of 63 μm (JIS Z8801-1: 2006), and saline solution (salt concentration 0.9 weight). %) Immersed in 1,000 ml for 1 hour without stirring. Then, it was lifted from the saline solution, hung for 15 minutes, drained, placed in a centrifuge with the tea bag, and dehydrated at 150 G for 90 seconds to remove excess saline solution. The weight (h1) including the tea bag after dehydration was measured. Further, the weight of the tea bag operated in the same manner except that the crosslinked polymer particles were not added was measured (h2), and the water retention amount was determined from the following formula.
Water retention (g / g) = (h1)-(h2)
The temperature of the physiological saline used and the measurement atmosphere was 25 ° C ± 2 ° C.

<Measurement of gel elastic modulus>
Artificial urine [200 parts by weight of urea, 80 parts by weight of sodium chloride, 8 parts by weight of magnesium sulfate (7 water salt), 3 parts by weight of calcium chloride (dihydrate), 2 parts by weight of ferric sulfate (7 water salt), ion 9704 parts by weight of exchanged water] Weigh 60.0 g into a 100 ml beaker (inner diameter 5 cm), and weigh 2.0 g of water-absorbent resin particles (P) in the same manner as described in JIS K7224-1996. It was put into a beaker to make a 30-fold swelling gel. Next, the beaker containing the 30-fold swelling gel was wrapped and allowed to stand in an atmosphere of 40 ± 2 ° C for 3 hours and then in an atmosphere of 25 ± 2 ° C for 0.5 hours, and then the gel elasticity of the 30-fold swelling gel was obtained. The rate was measured using a card meter Max ME-500 manufactured by Aitec Techno Engineering Co., Ltd. under the following conditions.
(Conditions for card meter)
・ Pressure sensitive shaft: 8mm
・ Spring: for 100g ・ Load: 100g
・ Rising speed: 1 inch / 7 seconds ・ Test properties: Breaking ・ Measurement time: 6 seconds ・ Measurement atmosphere temperature: 25 ± 2 ° C

<Reference manufacturing example 14>
8 g / of 25 wt% cationic organic polymer (c2-4) aqueous solution on non-woven fabric (b-1) {nonwoven fabric grain: 25 g / m ² , manufactured by Toyobo Co., Ltd. 2.2T 44-SMK} which is a diffusible member (B). The non-woven fabric (b-5) was obtained by spraying uniformly so as to be ^m2 .

<Reference manufacturing example 15>
8 g of a 25 wt% cationic organic polymer (c2-4) aqueous solution on a water-permeable sheet (b-2) {meshing 15.5 g / m ² , manufactured by Advantech, filter paper No. 2} which is a diffusible member (B). A water-permeable sheet (b-6) was obtained by spraying uniformly at / m ² .

<Reference manufacturing example 16>
10 parts of a 30 wt% cationic organic polymer (c2-1) aqueous solution was uniformly added to 100 parts of the hydrophilic fiber (b-3) {fluff pulp} which is the diffusible member (B) by spraying, and the hydrophilic fiber ( b-7) was obtained.

<Reference manufacturing example 17>
1000 parts of 2 wt% cationic organic polymer (c2-4) aqueous solution of "nonwoven fabric (b-4) {nonwoven fabric grain: 22 g / m ² , manufactured by HAVIX Corporation, thermal bonded non-woven fabric S2260}" which is a diffusible member (B). After immersing in the cloth for 1 hour, the diffusible member (B) was taken out and dried in a circulating air dryer at 40 ° C. for 1 hour to obtain a non-woven fabric (b-8).

<Example 1>
Non-woven fabric (b-1) which is a non-woven fabric (b-1) uniformly diffusible member (B) so that the water-absorbent resin particles (P-5) have a grain size of 200 g / m ² , {non-woven fabric grain: 25 g / m ² , manufactured by Toyobo Co., Ltd. 2.2T. 44-SMK} was sprinkled by hand, and water was uniformly sprayed from above to a concentration of 17.5 g / m ² to obtain an absorber (1). The absorbent body (1) is cut into a rectangle of 10 cm × 40 cm, and the absorbent body (1) is a water-permeable sheet (b-2) which is a diffusible member (B) having the same size as the absorbent body (1). An absorber (1-1) was obtained by sandwiching it with filter paper No. 2}, 15.5 g / m ² , manufactured by Advantech. Furthermore, as a back sheet, a polyethylene sheet (polyethylene film UB-1 manufactured by Tamapoli) is placed on the back surface, and a non-woven fabric (b-1) (nonwoven fabric basis weight: 25 g / m ² , 2.2T 44-SMK manufactured by Toyobo Co., Ltd.) is placed on the outermost surface. The absorbent article (1) was prepared by the above.

<Reference example 2>
The same as in Example 1 except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-1) and the non-woven fabric (b-1) was changed to the non-woven fabric (b-5). An absorbent article (2) was prepared.

<Reference example 3>
Example 1 except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-1) and the water-permeable sheet (b-2) was changed to the water-permeable sheet (b-6). The absorbent article (3) was prepared in the same manner as above.

<Reference example 4>
The water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-1), and 17.5 g / m ² of water was changed to 8 g / m ² of a 25 wt% cationic organic polymer (c2-4) aqueous solution. An absorbent article (4) was prepared in the same manner as in Example 1 except that the above was changed to.

<Example 5>
20 parts of the hydrophilic fiber (b-3) {fluff pulp} and 80 parts of the water-absorbent resin particles (P-5) are mixed by an air flow type mixer {padformer} to obtain a mixture, and then this mixture is obtained. Is evenly laminated on an acrylic plate (thickness 4 mm) so as to have a grain size of 250 g / m ² , and water is sprayed evenly from above so as to be 17.5 g / m ² , and 30 at a pressure of 5 kg / cm ² . Pressing for seconds gave the absorber (2). This absorber (2) is cut into a rectangle of 10 cm x 40 cm, and a water-permeable sheet (b- ² ) of the same size as the absorber is placed above and below each. No. 2} was placed to obtain an absorber (2-1). Furthermore, as a back sheet, a polyethylene sheet (polyethylene film UB-1 manufactured by Tamapoli) is placed on the back surface, and a non-woven fabric (b-1) {nonwoven fabric basis weight: 25 g / m ² , 2.2T 44-SMK manufactured by Toyobo Co., Ltd.} is placed on the front surface. The absorbent article (5) was prepared by the above. The weight ratio of the water-absorbent particles to the hydrophilic fibers (weight of the water-absorbent resin particles / weight of the hydrophilic fibers) was 80/20.

<Reference example 6>
Example 5 except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-1) and the hydrophilic fibers (b-3) were changed to the hydrophilic fibers (b-7). The absorbent article (6) was prepared in the same manner as above.

<Example 7>
Absorbency in the same manner as in Example 5, except that "nonwoven fabric (b-1)" was changed to "nonwoven fabric (b-4) {nonwoven fabric basis weight: 22 g / m ² , manufactured by HAVIX Corporation, thermal bond non-woven fabric S2260}". Article (7) was prepared.

<Example 8>
The absorbent article was changed from 20 parts to 50 parts of the hydrophilic fiber (b-3) and from 80 parts to 50 parts of the water-absorbent resin particles (P-5) in the same manner as in Example 5. (8) was prepared.

<Reference example 9>
The water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-1), and 17.5 g / m ² of water was changed to 8 g / m ² of a 25 wt% cationic organic polymer (c2-4) aqueous solution. The absorbent article (9) was prepared in the same manner as in Example 5 except for the modification.

<Example 10>
The absorbent article (10) was prepared in the same manner as in Example 1 except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-6).

<Reference example 11>
Example 5 except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-1) and the water-permeable sheet (b-2) was changed to the water-permeable sheet (b-6). The absorbent article (11) was prepared in the same manner as above.

<Reference example 12>
The water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-1), and the non-woven fabric (b-1) placed on the outermost surface (nonwoven fabric grain: 25 g / m ² , manufactured by Toyobo Co., Ltd. 2.2T) An absorbent article (12) was prepared in the same manner as in Example 5, except that 44-SMK) was changed to a non-woven fabric (b-5).

<Example 13>
The absorbent article (13) was prepared in the same manner as in Example 5 except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-7).

<Example 14>
The absorbent article (14) was prepared in the same manner as in Example 5 except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-8).

<Reference example 15>
Example 5 except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-3) and the water-permeable sheet (b-2) was changed to the water-permeable sheet (b-6). The absorbent article (15) was prepared in the same manner as above.

<Reference example 16>
An absorbent article (16) was prepared in the same manner as in Reference Example 15 except that the water permeable sheet (b-6) was changed to a non-woven fabric (b-8).

<Reference example 17>
Examples except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (P-3) and the non-woven fabric (b-1) arranged on the outermost surface was changed to the non-woven fabric (b-8). The absorbent article (17) was prepared in the same manner as in 5.

<Comparative Example 1>
An absorbent article (H1) was prepared in the same manner as in Example 1 except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (R-1).

<Comparative Example 2>
An absorbent article (H2) was prepared in the same manner as in Example 5 except that the water-absorbent resin particles (P-5) were changed to the water-absorbent resin particles (R-2).

Examples 1, Reference Examples 2 to 4, Example 5, Reference Example 6, Examples 7 to 8, Reference Example 9, Example 10, Reference Examples 11 and 12, Examples 13 and 14, Reference Examples 15 to 17 obtained. With respect to the absorbed absorbent articles (1 to 17) obtained and the comparative absorbent articles (H1, H2) obtained in Comparative Examples 1 and 2, the shape retention and the leakage performance after the absorber breakage test were evaluated by the following methods. The results are shown in Table 2.

<Measurement of shape retention>
Examples 1, Reference Examples 2 to 4, Example 5, Reference Example 6, Examples 7 to 8, Reference Example 9, Example 10, Reference Examples 11 and 12, Examples 13 and 14, Reference Examples 15 to 17 and The central portion of each of the absorber articles obtained in Comparative Examples 1 and 2 was cut into 8 cm × 3 cm with scissors, and each was placed in a 10 cm × 14 cm zippered bag. After filling the bags with nitrogen gas and chucking the bags, each bag was shaken by hand 10 times for 10 seconds. The chuck was opened and 12 g of saline was absorbed into the cut sample. Five minutes after the saline solution was added, the bag was filled with nitrogen gas again, chucked, and then shaken by hand 20 times for 20 seconds for each bag. After that, the shape of the cut sample was confirmed, and the evaluation was performed by dividing the sample into 1 to 5 points based on the following criteria.
1: Disjointed form;
2: A form in which most of the disjointed parts are partly lumpy parts;
3: A form in which the disjointed part and the mass part are half and half;
4: A form in which most of the mass parts are disjointed parts;
5: Form of one mass.

<Leakage performance after absorber breakage test>
Examples 1, Reference Examples 2 to 4, Example 5, Reference Example 6, Examples 7 to 8, Reference Example 9, Example 10, Reference Examples 11 and 12, Examples 13 and 14, Reference Examples 15 to 17 and A metal ring (inner diameter 70 mm, length 50 mm) is set in the center of each of the absorber articles obtained in Comparative Examples 1 and 2, 80 ml of artificial urine is injected, and when the artificial urine is completely absorbed, the gloss due to the artificial urine is increased. Until it could not be confirmed}, the metal ring was immediately removed and left for 5 minutes. The operation of holding both ends (10 cm side) of the absorbent article and bending it so as to fold the central portion is repeated 50 times to break the absorbent body swelling portion in the central portion. After that, set both ends (10 cm side) of the absorbent article up and down on a plate inclined at an angle of 45 degrees, and set it 5 cm below the top of the absorber (position 5 cm from the 10 cm side toward the center). 40 ml of artificial urine is dropped onto the portion (position 5 cm from the side of 40 cm toward the center) at a flow rate of 10 ml / sec using a dropping funnel. After 5 minutes, 40 ml of artificial urine is dropped again by the same operation, and the same operation is repeated every 5 minutes until the artificial urine leaks from the absorber, and the number of drops at the time of leakage is recorded.
The artificial urine, the measurement atmosphere, and the neglected atmosphere were performed at 25 ± 5 ° C. and 65 ± 10% RH.

As can be seen from Table 2, the absorbent article of the present invention was superior in the absorbent body retention after swelling as compared with the absorbent article for comparison. Therefore, when the absorbent article of the present invention is used, it is excellent in the shape retention of the absorber and the absorbency of the aqueous liquid even when a force is applied from the outside, and a constant force is continuously or discontinuously applied to the absorption site. However, it is easily predicted that the absorbing portion will not be torn or twisted, that there will be no liquid leakage due to a decrease in absorption capacity, and that the accompanying skin irritation will not occur.

The absorbent article of the present invention is useful for children's disposable diapers, adult disposable diapers, pet sheets, panty liners, incontinence pads, sweat absorbing sheets, medical blood absorbent articles, wound protectants, wound healing agents, surgical waste liquid treatment agents and the like. Is.

Claims (7)

A water-absorbent resin having a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) that becomes a water-soluble vinyl monomer (a1) by hydrolysis and a cross-linked polymer (A) having a cross-linking agent (b) as an essential constituent unit. An absorber containing 0.05 to 20% by weight of a gel particle shape-retaining agent (C) based on the weight of the particles (P), the liquid diffusing member (B), and the liquid diffusing member (B). The gel particle shape-retaining agent (C) is an absorber, which is a cationic organic polymer (c2) having a number average molecular weight of 400,000 to 5 million and having a structural unit represented by the following general formula (1). A step of uniformly mixing a gel particle shape-retaining agent (C) with a water-absorbent resin particle (P) before forming an absorber, and a gel particle shape-retaining agent. A method for producing an absorbent article, which comprises a step of uniformly mixing (C) and water-absorbent resin particles (P) and adhering the mixture to the surface of the liquid diffusion member (B).

[In the formula, R ¹ and R ² are the same or different, an alkyl group having a hydrogen atom or 1 to 4 carbon atoms, R ³ is a hydrogen atom or a methyl group, and Q is an alkylene having 1 to 4 carbon atoms. A group, X is an oxygen atom or an imino group, and Z ^- represents a conjugated base of Bronsted acid. ] The structural unit represented by the general formula (1) is aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, alkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, dialkyl. (1 to 4 carbon atoms) Aminoalkyl (1 to 4 carbon atoms) (meth) acrylate, aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide, alkyl (1 to 4 carbon atoms) Aminoalkyl (1 to 4 carbon atoms) 4) A structural unit derived from at least one cationic monomer selected from the group consisting of (meth) acrylamide and dialkyl (1 to 4 carbon atoms) aminoalkyl (1 to 4 carbon atoms) (meth) acrylamide. The manufacturing method according to claim 1. The production according to claim 1 or 2, wherein the cationic organic polymer (c2) is polydimethylaminoethyl methacrylate / sulfate, polyaminoethyl methacrylate / methanesulfonate, or polyaminoethyl methacrylate / camphor sulfonate. Method. The production method according to any one of claims 1 to 3, wherein the gel particle shape-retaining agent (C) has a number average molecular weight of 400,000 to 950,000. The production method according to any one of claims 1 to 4, wherein the content of the gel particle shape-retaining agent (C) is 2 to 10% by weight based on the weight of the liquid diffusible member (B). In the step of uniformly mixing the gel particle shape-retaining agent (C) and the water-absorbent resin particles (P) and adhering them to the surface of the liquid diffusion member (B), the gel particle shape-retaining agent (C) and the water-absorbent resin particles are attached. The production method according to any one of claims 1 to 5, which is a step of sprinkling a uniformly mixed mixture of (P) on a non-woven fabric which is a liquid diffusion member (B). In the step of uniformly mixing the gel particle shape-retaining agent (C) and the water-absorbent resin particles (P) and adhering them to the surface of the liquid diffusion member (B), the gel particle shape-retaining agent (C) and the water-absorbent resin particles are attached. The production method according to any one of claims 1 to 5, which is a step of mixing a uniform mixture of (P) with hydrophilic fibers which are liquid diffusion members (B).