JPH11267500A - Water absorbent and absorptive product using that - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart an excellent antibacterial effect and absorption characteristics to absorptive products even when a resin is assembled in high resin concn. into the products by using a water absorbent containing an antibacterial agent and having specified absorption magnification under pressure and a specified water absorption rate. SOLUTION: This absorbent used in an absorbing body of a sanitary material such as paper diaper and sanitary napkin is prepared from a water-absorbing resin which contains an antibacterial agent and satisfies the conditions of >=25 (g/g) absorption magnification under pressure and a water absorption rate between >=20 sec and <=50 sec. The such water-absorbing resin is obtd. by a manufacturing method of the surface crosslinking treatment of a specified water- absorbing resin precursor under specified conditions. As the water-absorbing resin precursor for example, partially neutralized crosslinked polyacrylic acids and hydrolyzed starch-acrylonitrile grafted polymer can be used. As the antibacterial agent, quaternary ammonium salt-based compds. and/or biguanide compds. are used. The antibacterial agent is incorporated by 0.001 to 5 pts.wt. to 100 pts.wt. of the water absorbent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to a water-absorbing agent and an absorbent article using the water-absorbing agent. More particularly, it is excellent when used in an absorbent for sanitary materials such as disposable diapers, sanitary napkins and incontinence pads. And a water-absorbing agent capable of imparting antibacterial function and water-absorbing properties.

[0002]

2. Description of the Related Art In recent years, water-absorbent resins have been widely used as one of the constituent materials of sanitary materials such as disposable diapers, sanitary napkins and incontinence pads for the purpose of absorbing body fluids.

Examples of the water-absorbing resin include a crosslinked product of a partially neutralized polyacrylic acid, a hydrolyzate of a starch-acrylonitrile graft polymer, a neutralized product of a starch-acrylic acid graft polymer, and vinyl acetate-acrylic acid. Saponified ester copolymer, cross-linked carboxymethyl cellulose,
Hydrolyzate of acrylonitrile copolymer or acrylamide copolymer or cross-linked product thereof, cross-linked product of cationic monomer, cross-linked isobutylene-maleic acid copolymer, cross-linking of 2-acrylamido-2-methylpropane sulfonic acid and acrylic acid The body is known.

[0004] Conventionally, the water-absorbing properties desired for the above-mentioned water-absorbing resin include high absorption capacity when contacted with an aqueous liquid such as a body fluid, excellent water absorption rate, liquid permeability, gel strength of a swollen gel,
A suction amount or the like for sucking water from a base material containing an aqueous liquid has been proposed.

[0005] In addition, various attempts have conventionally been made to add an antibacterial compound to the water-absorbing resin to give the resin an additional function.

Examples of these include disposable diapers containing a resin containing benzalkonium chloride and / or chlorhexidine gluconate in a water-absorbing resin (JP-A-63-135).
No. 501), an antibacterial resin composition in which an antibacterial agent is dissolved or dispersed in a volatile solvent is attached to a water-absorbent resin, and then the volatile solvent is removed to form an antibacterial coating on the surface of the water-absorbent resin. Production method (JP-A-3-59075) Water-absorbing resin containing phosphate with antibacterial property (JP-A-5-1790)
No. 53, JP-A-7-165981) chlorhexidine,
An antibacterial water-absorbing composition containing or carrying an antibacterial component comprising a polymethylenebiguanidine organic acid salt and a quaternary ammonium organic acid salt (JP-A-9-248454) is known.

In recent years, absorbent articles such as disposable diapers have become thinner, and the amount of water-absorbing resin used in the absorbent layer has tended to increase. That is, in the absorbent layer of an absorbent article such as a disposable diaper, the weight ratio of the water-absorbent resin to the total amount of the water-absorbent resin and the fiber base (hereinafter, may be referred to as resin concentration) is 0.
Three or more, and even more than 0.5 are becoming mainstream. However, it has been found that there is still a problem when such a water-absorbent resin is used for an absorbent article such as a paper diaper having a high resin concentration simply by adding an antibacterial compound to the water-absorbent resin. That is, the present inventors have conducted a detailed study on a water-absorbent resin containing an antibacterial agent, and as a result, generally, an absorbent article such as a diaper using a water-absorbent resin containing an antibacterial agent has a high antibacterial property when the resin concentration is high. It has been found that there is a tendency that the absorption characteristics such as the return amount are greatly reduced as compared with the case where a water-absorbing resin to which no agent is added is used. It has also been found that depending on the type of the water-absorbing resin, the antibacterial performance may not be sufficiently imparted to the entire diaper.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a water-absorbing agent capable of imparting excellent antibacterial action and excellent absorption characteristics even when incorporated into an absorbent article such as a diaper at a high resin concentration. It is to provide a manufacturing method.

Another object of the present invention is to provide an absorbent article having excellent antibacterial performance and excellent absorption properties and having a high resin concentration.

[0010]

DISCLOSURE OF THE INVENTION The present inventors provide a water absorbing agent,
As a result of intensive studies from the viewpoint of excellent antibacterial properties and excellent absorption characteristics when incorporating a high resin concentration into absorbent articles such as diapers, the above-mentioned object was found when an antibacterial agent and a water-absorbent resin having specific physical properties were combined. Have been achieved, and the present invention has been completed.

That is, the water-absorbing agent of the invention according to claim 1 is:
It is characterized by comprising a water-absorbing agent containing an antibacterial agent and having an absorption capacity under pressure of 25 (g / g) or more and a water absorption speed of 20 seconds or more and 50 seconds or less.

[0012] The method for producing a water-absorbing agent according to the present invention is characterized in that an antibacterial agent is added to a water-absorbing resin having an absorption capacity under pressure of 25 (g / g) or more and a water absorption rate of 20 seconds to 50 seconds. This is a method for producing a water absorbing agent characterized by the following.

The weight ratio α of the water-absorbing resin to the total amount of the water-absorbing resin and the fiber base material is as follows.
An absorbent article comprising an absorbent layer containing an absorbent having a particle size of 0.3 or more, a liquid-permeable topsheet, and a liquid-impermeable backsheet, comprising an antibacterial agent and having an absorption capacity under pressure of 25.
(g / g) or more and a water-absorbing agent having a water absorption speed of 20 seconds or more and 50 seconds or less.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The water-absorbing resin which can be used in the present invention satisfies the two conditions of an absorption capacity under pressure of 25 (g / g) or more and a water absorption rate of 20 seconds to 50 seconds. When the value of the absorption capacity under pressure is less than 25 (g / g), even when the water absorption rate satisfies the value range of the present invention, in combination with the antibacterial agent, the return amount when the absorbent article is formed. It is not preferable because it cannot be reduced. Preferably, the resin has an absorption capacity under pressure of 30 (g / g) or more, more preferably 32 (g / g) or more. The water absorption speed is 20 seconds or more and 50 seconds or less, preferably 25 seconds or more and 45 seconds or less. When the water absorption rate exceeds 50 seconds, the amount of return in the case of an absorbent article cannot be reduced when combined with an antibacterial agent. If the time is shorter than 20 seconds, a stable antibacterial action may not be imparted to the absorbent article.

Such a water-absorbent resin is generally obtained by a production method in which a specific water-absorbent resin precursor is subjected to surface crosslinking under specific conditions. The above water-absorbent resin precursor preferably has an average particle size in the range of 150 μm to 600 μm, more preferably an average particle size in the range of 200 μm to 400 μm, and has a specific surface area of 0.025 by the so-called BET method. m ² or more
It is about 0.035m ² or less.

The water-absorbing resin precursor is synthesized, for example, by aqueous solution polymerization or reverse phase suspension polymerization. Specific examples of the water-absorbent resin precursor include, for example, a crosslinked product of partially neutralized polyacrylic acid, a hydrolyzate of starch-acrylonitrile graft polymer, a neutralized product of starch-acrylic acid graft polymer, and acetic acid. Saponified vinyl-acrylate copolymer, hydrolyzate of acrylonitrile copolymer or acrylamide copolymer or cross-linked product thereof, carboxyl group-containing cross-linked polyvinyl alcohol-modified product, cross-linked isobutylene-maleic anhydride copolymer, etc. Is mentioned.

The above-mentioned water-absorbing resin precursor includes, for example, unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, β-acryloyloxypropionic acid, and the like. After polymerizing or copolymerizing one or more monomers selected from neutralized products of the above, the polymer is subjected to operations such as pulverization and classification as necessary to adjust the average particle size to the above. can get. Among the above monomers, (meth) acrylic acid and their neutralized products are more preferable.

Further, the water-absorbing resin precursor may be a copolymer of the above monomer and another monomer copolymerizable with the monomer. As the other monomer, specifically,
For example, vinyl sulfonic acid, styrene sulfonic acid, 2-
(Meth) acrylamide-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, 2-
Anionic unsaturated monomers such as (meth) acryloylpropanesulfonic acid and salts thereof; acrylamide, methacrylamide, N-ethyl (meth) acrylamide, N
-N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) ) Nonionic hydrophilic group-containing unsaturated monomers such as acrylate, polyethylene glycol mono (meth) acrylate, vinylpyridine, N-vinylpyrrolidone, N-acryloylpiperidine, N-acryloylpyrrolidine; N, N-dimethylaminoethyl ( (Meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, and quaternary salts thereof And cationic unsaturated monomers such.

It is essential that the water absorbing resin precursor is internally crosslinked by reacting or copolymerizing with a crosslinking agent having a plurality of polymerizable unsaturated groups or a plurality of reactive groups. Specific examples of the crosslinking agent include N, N'-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, and trimethylolpropane. Di (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, glycerin acrylate methacrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meta) ) Acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, triallylamine, poly (meth) allyloxyalkane, (poly) ethylene glycol Chole diglycidyl ether, glycerol diglycidyl ether,
Ethylene glycol, polyethylene glycol, propylene glycol, glycerin, pentaerythritol,
Ethylenediamine, polyethyleneimine, glycidyl (meth) acrylate and the like can be mentioned. These crosslinking agents may be used alone or as a mixture of two or more. Among the compounds exemplified above, it is more preferable to use a compound having a plurality of polymerizable unsaturated groups as a crosslinking agent.

The amount of the crosslinking agent used is preferably in the range of 0.01 mol% to 2 mol% with respect to the total amount of the above monomers,
More preferably, it is in the range of 3 mol% to 0.2 mol%.

At the start of the polymerization, for example, potassium persulfate, ammonium persulfate, sodium persulfate,
t-butyl hydroperoxide, hydrogen peroxide, 2,
A radical polymerization initiator such as 2′-azobis (2-amidinopropane) dihydrochloride or an active energy ray such as an ultraviolet ray or an electron beam can be used. When an oxidizing radical polymerization initiator is used, redox polymerization may be performed using a reducing agent such as sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, or L-ascorbic acid in combination. The amount of these polymerization initiators used is preferably in the range of 0.001 mol% to 2 mol%, more preferably in the range of 0.01 mol% to 0.5 mol%.

It is also preferable to use a method in which a foaming agent such as a carbonate or an azo compound, an inert gas, or the like is added to the monomer during polymerization, and the resulting water-absorbent resin precursor has a porous structure to adjust the specific surface area. .

The above-mentioned water-absorbent resin precursor may be granulated in a predetermined shape, or may be in various shapes such as spherical, scale-like, irregularly crushed, and granular. Further, the water absorbing resin precursor may be primary particles,
Granules of secondary particles may be used.

The above-mentioned water-absorbent resin precursor preferably has an average particle size in the range of 150 μm to 600 μm, more preferably an average particle size in the range of 200 μm to 400 μm,
The specific surface area by the so-called BET method is 0.025 m ² or more and 0.035 m ²
It is about the following.

By using these particles and cross-linking the vicinity of the surface described below, a water-absorbing resin having a water absorption rate of 20 seconds to 50 seconds, preferably 25 to 40 seconds can be obtained.

The above water-absorbing resin precursor generally has an absorption capacity under pressure that does not satisfy the range in the present invention.
For this reason, it is necessary to make the crosslink density near the surface of the water-absorbent resin precursor higher than that inside by using a surface crosslinker. That is, a water-absorbent resin that can be used in the present invention can be obtained by crosslinking the vicinity of the surface of the water-absorbent resin precursor using a specific surface cross-linking agent.

That is, the water-absorbent resin according to the present invention is preferably a water-absorbent resin precursor obtained by the above-mentioned aqueous solution polymerization, that is, having an average particle size in the range of 150 μm to 600 μm.
More preferably, those obtained by adjusting by polymerization, classification and the like so that the average particle diameter is in the range of 200 μm to 400 μm are heat-treated in the presence of a surface cross-linking agent, and then subjected to a specific pressure. It is obtained by processing so as to have an absorption capacity value.

The surface cross-linking agent has a functional group of the water-absorbent resin precursor, for example, a functional group capable of reacting with an acidic group. Examples of the surface cross-linking agent include well-known cross-linking agents which are usually used for the purpose. You.

When the functional group of the water absorbent resin precursor is, for example, a carboxyl group, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, Dipropylene glycol, 2,2,4-trimethyl-1,3-pentadiol, polypropylene glycol, glycerin, polyglycerin, 2-butene-
1,4-diol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,2
Polyhydric alcohol compounds such as cyclohexanedimethanol, 1,2-cyclohexanol, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethyleneoxypropylene block copolymer, pentaerythritol and sorbitol; ethylene glycol diglycidyl Ether, polyethylene diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polyhydric epoxy compounds such as glycidol; ethylenediamine, diethylenetriamine, Triethylenetetramine, tetraethylenepentamine, pentae Renhekisamin, polyallylamine, polyamine compounds such as polyethyleneimine; 2,4
Polyvalent isocyanate compounds such as tolylene diisocyanate and hexamethylene diisocyanate; polyvalent oxazoline compounds such as 1,2-ethylenebisoxazoline;
1,3-dioxolan-2-one, 4-methyl-1,3
-Dioxolan-2-one, 4,5-dimethyl-1,3
Dioxolan-2-one, 4,4-dimethyl-1,3
-Dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-
Dioxolan-2-one, 1,3-dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,
6-dimethyl-1,3-dioxan-2-one, 1,3
Alkylene carbonate compounds such as dioxopan-2-one; epichlorohydrin, epibromohydrin, α
-A haloepoxy compound such as methyl epichlorohydrin;
Zinc, calcium, magnesium, aluminum, iron,
Polyhydric metal compounds such as hydroxides and chlorides such as zirconium; γ-glycidoxypropyltrimethoxysilane, γ
Silane coupling agents such as -aminopropyltriethoxysilane; and one or more silane coupling agents. Preferably, polyhydric alcohol compounds, polyamine compounds, polyepoxy compounds, and alkylene compounds
It contains at least one member selected from the group consisting of carbonate compounds.

The amount of the surface cross-linking agent used depends on the compound to be used and the combination thereof, but is preferably in the range of 0.001 to 5 parts by weight based on 100 parts by weight of the solid content of the water-absorbing resin precursor. And more preferably in the range of 0.01 to 1 part by weight. By using the above surface cross-linking agent, the water-absorbing resin precursor, that is, the cross-linking density near the surface of the water-absorbing resin can be higher than the inside, and the value of the absorption capacity under pressure required for the resin of the present invention is increased. What you have. When the amount of the surface cross-linking agent exceeds 10 parts by weight, not only is it uneconomical, but also because the amount of the surface cross-linking agent becomes excessive in forming the optimum cross-linked structure in the water-absorbing resin, the absorption capacity is increased. Is undesirably reduced. In addition, the amount of the surface crosslinking agent used is 0.001
When the amount is less than part by weight, the value of the absorbency against pressure of the water-absorbent resin may not be easily improved.

When mixing the water-absorbing resin precursor and the surface crosslinking agent, it is preferable to use water as a solvent. The amount of water used depends on the type and particle size of the water-absorbing resin precursor, but is 0% based on 100 parts by weight of the solid content of the water-absorbing resin precursor.
And preferably not more than 20 parts by weight, more preferably in the range of 0.5 to 10 parts by weight.

When mixing the water-absorbing resin precursor with the surface crosslinking agent, a hydrophilic organic solvent may be used as a solvent, if necessary. As the above hydrophilic organic solvent,
For example, lower alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol; ketones such as acetone;
Ethers such as dioxane and tetrahydrofuran;
Amides such as N-dimethylformamide; sulfoxides such as dimethyl sulfoxide; and the like. The amount of the hydrophilic organic solvent used depends on the type and particle size of the water-absorbing resin precursor, but is preferably 20 parts by weight or less, and more preferably 0.1 part by weight, based on 10 parts by weight of the solid content of the water-absorbing resin precursor. More preferably, it is within the range of 10 to 10 parts by weight.

When mixing the water-absorbing resin precursor and the surface cross-linking agent, for example, after dispersing the water-absorbing resin precursor in the above-mentioned hydrophilic organic solvent, the surface cross-linking agent is mixed. However, the mixing method is not particularly limited. Among various mixing methods, a method in which a surface cross-linking agent dissolved in water and / or a hydrophilic organic solvent, if necessary, is directly sprayed or dropped onto the water-absorbent resin precursor and mixed. In the case of mixing using water, fine powder insoluble in water, a surfactant or the like may be allowed to coexist.

The mixing device used for mixing the water-absorbent resin precursor and the surface crosslinking agent preferably has a large mixing force in order to uniformly and surely mix the two. As the mixing device, for example, a cylindrical mixer,
Double wall conical mixer, V-shaped mixer, ribbon mixer,
Suitable examples include a screw mixer, a fluid-type furnace rotary desk mixer, an airflow mixer, a double-arm kneader, an internal mixer, a pulverizing kneader, a rotary mixer, and a screw extruder.

After mixing the water-absorbing resin precursor and the surface cross-linking agent, a heat treatment is performed to crosslink the vicinity of the surface of the water-absorbing resin precursor. The temperature of the heat treatment depends on the surface cross-linking agent used, but is preferably from 40 ° C. to 250 ° C. When the treatment temperature is lower than 40 ° C., a uniform crosslinked structure is not formed, so that a water-absorbent resin having an absorption capacity under pressure falling within the range of the present invention may not be obtained. Processing temperature
If the temperature exceeds 250 ° C., the water-absorbent resin may be deteriorated, and the performance of the water-absorbent resin may be reduced.

The above-mentioned heat treatment can be performed using a usual dryer or heating furnace. Examples of the dryer include a groove-type mixing dryer, a rotary dryer, a desk dryer, a fluidized-bed dryer, a flash dryer, and an infrared dryer.

In order to obtain a water-absorbent resin which can be used in the present invention, the absorbency against pressure is 25 (g / g) or more, preferably 30 (g / g) or more.
It is essential to control the above-mentioned cross-linking agent, mixing method, heating temperature, treatment time and the like so as to be not less than (g / g), more preferably not less than 32 (g / g).

The water-absorbing agent of the present invention can be obtained by adding an antibacterial agent to the water-absorbing resin having an absorption capacity under pressure of 25 (g / g) or more and a water absorption rate of 20 seconds to 50 seconds obtained above. .

The antibacterial agents that can be used in the present invention include:
Alcohol compounds such as, but not limited to, known compounds having antibacterial properties, such as, but not limited to, 2-bromo-2-nitro-1, 3-propanediol, and N- (2-hydroxypropyl) -aminomethanol; Phenol, 3-methyl-4-
Isopropylphenol, 2-isopropyl-5-methylphenol, o-phenylphenol, sodium o-phenylphenol, 4-chloro-3, 5-dimethylphenol, p-chlorom-cresol, tribromophenol,
Phenolic compounds such as 4-chloro-2-phenylphenol; carboxylic compounds such as undecylenic acid compounds, sorbic acid, potassium sorbate, and caprylic acid; ester compounds such as fatty acid monoglycerides and p-hydroxybenzoic acid esters; Ether compounds such as 2,4,4'-trichloro-2'-hydroxydiphenyl ether; 2,4,5,
6-tetrachloroisophthalonitrile, 1,2-dibromo-2,4
Nitrile compounds such as -dicyanobtan; halogen antibacterial agents such as chlorinated isocyanuric acid, α-chloronaphthalene, polyvinylpyrrolidone iodine; (2-pyridylthio-1
-Oxide), 2.3.5.6-tetrachloro-4 (methylsulfonyl) pyridine and other pyridine / quinoline antibacterial agents; hexahydro-1,3,5-tris (2-hydroxyethyl) -S-
Triazine compounds such as triazine; 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 1 And isothiazolone compounds such as 2-benzothiazolone; imidazole / thiazole compounds such as 2- (4-thiocyanomethylthio) benzimidazole, 2- (4′-thiazolyl) benzimidazole and 2-methoxycarbonylaminobenzimidazole; Anilide compounds such as 4,4-trichlorocarbanilide and 3-trifluoromethyl-4,4'-dichlorocarbanilide; polyhexamethylene biguanidine hydrochloride, polyhexamethylene biguanidine gluconate, chlorhexidine hydrochloride Biguanide compounds such as salts and chlorhexidine gluconate; disulfides such as bis (dimethylthiocarbamoyl) disulfide Compounds: polyglucosamine, chitosan, aminoglycoside ST
Carbohydrate compounds such as -7; tropolone antibacterial agents such as hinokitiol; alkylbenzyldimethylammonium salts (such as benzalkonium chloride), alkyldimethylammonium chloride, didecyldimethylammonium chloride, didecyldimethylammonium gluconate, and cetyl Dimethylbenzylammonium chloride, octadecylamine acetate, 3- (trimethoxysilyl) propyldimethyloctadecylammonium chloride, poly [polymethylene (dimethyliminio) chloride], poly [oxyethylene (dimethyliminio) ethylene (dimethyliminio) ethylene Quaternary ammonium salt compounds such as dichloride], alkyldi (aminoethyl)
Amphoteric and anionic surfactant compounds represented by glycine, aliphatic monoglyceride, etc .; inorganic compounds such as titanium oxide, apatite, silica gel, ceramic, calcium phosphate, zirconium phosphate, etc. carrying silver, copper, etc. can do.

Among these, a water-soluble and water-dispersible antibacterial agent is particularly preferably used from the viewpoint of imparting a stable antibacterial property to an absorbent article. Among them, a quaternary ammonium salt compound and a biguanide compound are particularly preferred. Is preferably used. Also, these quaternary ammonium salt compounds,
As the biguanide compound, both inorganic acid salts and organic acid salts can be preferably used.

Although such a water-soluble and water-dispersible antibacterial agent dissolves and disperses in an aqueous liquid such as urine, a general water-absorbing resin containing the antibacterial agent can be added to an absorbent article such as a disposable diaper. When used at a high height, the so-called return amount increases, which may cause discomfort to the wearer. The absorbent of the present invention solves the above problems by specifying the physical properties of the water-absorbent resin before mixing the antibacterial agent, and can impart excellent antibacterial properties and absorbent properties to the absorbent article, It is preferably used for absorbent articles having a high resin concentration.

It is preferable that the above problem can be reduced by controlling the release rate by supporting these antibacterial agents on a single substance. The carrier in this case is silicon dioxide, titanium dioxide, aluminum oxide, magnesium oxide, zinc oxide, clay, talc, calcium phosphate,
Zirconium phosphate, barium phosphate, silicic acid or its salt, clay, diatomaceous earth, silica gel, zeolite, bentonite, kaolin, hydroxyapatite, hydrotalcite, vermiculite, perlite, isolite, activated clay, silica sand, silica stone, Strontium ore,
Inorganic powders such as fluorite, bauxide, and glass; polyethylene, polypropylene, polyvinyl chloride, polystyrene,
Nylon, melamine resin, polymethyl methacrylate,
Organic powders such as starch, dextrin, cyclodextrin, cellulose, ethylcellulose, wood flour, activated carbon, tea leaves and the like can be exemplified, and one or more of these can be used. Preferred are inorganic powders such as zeolite, titanium oxide, apatite, silica gel, ceramic, silicic acid or a salt thereof, glass, calcium phosphate, zirconium phosphate and the like, and among them, poorly soluble phosphates are preferred.

The amount of these antibacterial agents used varies depending on the desired antibacterial function, but the amount of addition is preferably in the range of 0.001 to 5 parts by weight based on 100 parts by weight of the water-absorbent resin solids.

As a method of adding these antibacterial agents,
As a desired amount of antimicrobial agent is added to the water-absorbent resin, a method of spraying or mixing the antimicrobial agent directly onto the water-absorbent resin, dissolving or dispersing the antimicrobial agent in water, an aqueous liquid or various organic solvents, or the like. The method can be exemplified by a method of directly spraying or dripping and mixing the water-absorbent resin with the water-absorbent resin, a method of directly mixing a powder in which an antibacterial agent is previously supported on various inorganic or organic powders with the water-absorbent resin, or the like. In addition, it is also possible to adopt a method of adding an antibacterial agent at the time of polymerization of the water-absorbing resin, or a method of adding an antibacterial agent to the gel after polymerization. It is necessary to perform a surface cross-linking treatment or the like so as to fall within the range of the speed.

In the present invention, when the water-absorbing resin and the antibacterial agent are mixed, the amount of water, steam, or an aqueous liquid composed of water and a hydrophilic organic solvent used as needed depends on the type and particle size of the water-absorbing resin. The optimal amount is different, but usually
In the case of water, based on 100 parts by weight of the solid content of the water absorbent resin,
It is 10 parts by weight or less, preferably in the range of 1 to 5 parts by weight. Similarly, the amount of the hydrophilic organic solvent used is generally 10 parts by weight or less, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the solid content of the water-absorbent resin.

Various inorganic powders may be further added to the above water absorbing agent. Specific examples of the inorganic powder include metal oxides such as silicon dioxide and titanium oxide, silicic acids (salts) such as natural zeolite and synthetic zeolite, kaolin, talc, clay, bentonite and the like. Among them, silicon dioxide and silicic acid (salt) are more preferable, and the average particle diameter measured by the Coulter counter method is 20%.
Silicon dioxide and silicic acid (salt) of 0 μm or less are more preferred. The amount used depends on the combination of the water-absorbing agent and the inorganic powder, etc., but is 0.001 part by weight per 100 parts by weight of the water-absorbing agent.
10 to 10 parts by weight, more preferably 0.01 to 5 parts by weight. The method of mixing the water-absorbent resin and the inorganic powder is not particularly limited, and for example, a dry blending method, a wet mixing method, or the like can be employed, but the dry blending method is more preferable.

The water-absorbing agent obtained by the above production method is
A water-absorbing agent containing an antibacterial agent and having an absorption capacity under pressure of 25 (g / g) or more and a water absorption rate of 20 seconds to 50 seconds.

Further, in the absorbent article of the present invention, the weight ratio α of the water-absorbent resin to the total amount of the water-absorbent resin and the fibrous base material is 0.5.
An absorbent article comprising an absorbent layer containing an absorbent body that is 3 or more, a liquid-permeable top sheet, and a liquid-impermeable back sheet, which contains an antibacterial agent and has an absorption capacity under pressure of 25 (g / g). g)
It is characterized by including a water-absorbing agent having a water absorption speed of 20 seconds or more and 50 seconds or less. When the weight ratio α of the water-absorbent resin to the total amount of the water-absorbent resin and the fiber base material is less than 0.3, the amount of the water-absorbent resin used is relatively small, and the antibacterial function may not be sufficiently exerted. Will be many.

As described above, the water-absorbing agent of the present invention can stably impart an antibacterial function to an absorbent article, and exhibits excellent absorption performance that the amount of return is small even when the resin concentration is high. Specific examples of such absorbent articles include hygiene materials such as adult paper diapers, which have been growing rapidly in recent years, diapers for children, sanitary napkins, so-called incontinence pads, and the like, and are particularly limited to these. However, the water-absorbing agent present in the absorbent article has a very excellent and stable antibacterial function, and has a small amount of return and a remarkable dry feeling. The burden can be greatly reduced.

[0051]

The water-absorbing agent of the present invention can stably impart antibacterial performance, and in this case, the problem of an increase in the amount of return, which has been a problem in conventional absorbent articles having a high resin concentration, is solved. It is a new water absorbing agent. Although the cause is not clear, the antibacterial agent is applied only to the water-absorbent resin having a specific absorption capacity under pressure and absorption rate, so that the antibacterial agent when contacted with urine under high resin concentration This is probably because the optimal balance between the release of the agent and its absorption has been achieved.

The absorbent article of the present invention contains the water-absorbing agent of the present invention, and can impart excellent antibacterial function and absorption properties. Therefore, paper diapers, sanitary napkins, adult incontinence pads, adult diapers, and the like. It is particularly suitable for use as a sanitary material, and can maintain an excellent wearing feeling over a long period of time.

[0053]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The various properties of the water-absorbent resin were measured by the following methods.

(A) Absorption capacity 0.2 g of the water-absorbing resin (or water-absorbing agent) was added to a nonwoven fabric bag (60 m
m × 60 mm) and immersed in a 0.9% by weight aqueous sodium chloride solution (physiological saline). After 60 minutes, the bag was lifted, and after draining with a centrifuge at 250 G for 3 minutes, the weight W1 (g) of the bag was measured. Further, the same operation was performed without using a water absorbing agent, and the weight W0
(G) was measured. Then, from these weights W1 and W0, the following formula: absorption capacity (g / g) = (weight W1 (g) −weight W0 (g)) /
The absorption capacity (g / g) was calculated according to the weight (g) of the water absorbent resin.

(B) Absorption Capacity Under Pressure First, a measuring apparatus used for measuring the absorption capacity under pressure will be briefly described below with reference to FIG.

As shown in FIG. 1, the measuring device is a balance 1
And a container 2 having a predetermined capacity mounted on the balance 1, an outside air suction pipe 3, a conduit 4, a glass filter 6, and a measuring unit 5 mounted on the glass filter 6. I have. The container 2 has an opening 2a at the top and an opening 2b at the side surface thereof.
The outside air suction pipe 3 is fitted into the opening a, and the conduit 4 is attached to the opening 2b. The container 2 contains a predetermined amount of physiological saline solution 11 (aqueous solution of 0.9% by weight of sodium chloride). The lower end of the outside air suction pipe 3 is submerged in the physiological saline 11. The glass filter 6 has a diameter of 70 mm. The container 2 and the glass filter 6 are in communication with each other by the conduit 4. The upper part of the glass filter 6 is fixed at a position slightly higher than the lower end of the outside air suction pipe 3. The measuring unit 5 includes a filter paper 7, a support cylinder 8, a wire mesh 9 attached to a bottom of the support cylinder 8,
And a weight 10. Then, the measuring unit 5 places the filter paper 7 and the support cylinder 8 (that is, the wire mesh 9) on the glass filter 6 in this order, and places the weight 10 inside the support cylinder 8, that is, on the wire mesh 9. It has been. The support cylinder 8 has an inner diameter of 60 mm. The wire mesh 9 is made of stainless steel and has a mesh of 400 mesh (mesh size of 38 μm).
m). Then, a predetermined amount of a water-absorbing resin (or a water-absorbing agent) is evenly spread on the wire mesh 9. The weight of the weight 10 is adjusted so that a load of 20 g / cm 2 can be uniformly applied to the wire mesh 9, that is, the water-absorbing resin.

The absorption capacity under pressure was measured using the measuring apparatus having the above-mentioned configuration. The measuring method will be described below.

First, predetermined preparation operations such as putting a predetermined amount of physiological saline 11 into the container 2 and fitting the outside air suction pipe 3 into the container 2 were performed. Next, the filter paper 7 was placed on the glass filter 6. On the other hand, in parallel with these mounting operations, 0.9 g of a water-absorbing resin (or water-absorbing agent) is evenly spread on the inside of the support cylinder, that is, on the wire mesh 9, and a weight 10 is placed on the water-absorbing resin.
Was placed.

Next, on the filter paper 7, the supporting cylinder 8 on which the wire netting 9, that is, the water-absorbent resin and the weight 10 was placed, was placed.

The weight W2 (g) of the physiological saline solution 11 absorbed by the water-absorbing resin was measured using the balance 1 for 60 minutes after the support cylinder 8 was placed on the filter paper 7. Then, from the above weight W2, the absorption capacity under pressure (g) 60 minutes after the start of absorption according to the following equation: absorption capacity under pressure (g / g) = weight W2 (g) / weight of water absorbent resin (g) / g)
Was calculated.

(B) Water Absorption Rate In a 100 ml beaker, 50 g of physiological saline (0.9% aqueous NaCl solution) adjusted to 30 ° C. and a stirrer are put in advance, and the mixture is stirred with a magnetic stirrer at a speed of 600 rpm.
When 2 g of the water-absorbent resin is introduced into the mixture, gelation occurs, the fluidity of the liquid decreases, and the vortex around the stirring center disappears. The time required until the rotating stirrer, which was initially visible, disappeared due to the rise of the vortex when the vortex disappeared after the sample was introduced was measured, and this was taken as the water absorption rate.

(C) Antibacterial test (water-absorbing agent) 0.1 g of a test sample was placed in a 15-ml test tube, and LB broth (DIFCO LABORATORIES) containing about 1 × 10 6 Escherichia coli / ml therein.
6 ml) to swell. This sample is shake-cultured at 37 ° C., sampled for 2 hours, and sampled 100 μl after 24 hours. If necessary, this is serially diluted with LB BROTH, uniformly applied to an LB BROTH agar medium in an amount of 100 μl each, and cultured at 37 ° C. overnight. After culturing, the number of colonies is counted and multiplied by a dilution factor to obtain the number of viable bacteria. When a test sample containing no antibacterial agent was used as a blank, the viable cell count was 4 × 10 ＾ 6 cells / ml after 2 hours, and 2 × 10 6 cells after 24 hours.
＾ 9 / ml.

(D) Return amount of absorbent article 50 parts by weight of water-absorbent resin and 50 parts by weight of ground wood pulp
Dry mixing was performed using a mixer. Next, the resulting mixture was air-formed on a wire screen formed into a 400 mesh (mesh size of 38 μm) using a batch-type air-forming device to form a web having a size of 100 mm × 100 mm. . Further, the web is subjected to a pressure of 2 kg / cm2.
For 5 seconds to obtain an absorbent having a basis weight of about 360 g / m2.

Subsequently, a back sheet (liquid-impermeable sheet) made of liquid-impermeable polypropylene, the above-described absorber, and a top sheet (liquid-permeable sheet) made of liquid-permeable polypropylene were placed in this order. By mounting, an absorbent article was obtained. The weight of this absorbent article is 3.6
g.

In the above absorbent article, artificial urine (2.0 g of KCl, 2.0 g of Na ₂ SO ₄ , 0.8 g of NH ₄ H ₂ P in 1 L of ion-exchanged water)
O ₄ , 0.15 g (NH ₄ ) ₂ HPO ₄ , 0.19 g CaCl ₂ , 0.23 g MgCl ₂
One minute after the addition of 40 g, a kitchen towel was folded into four pieces, placed on the top sheet, and a load of 10 kg was applied for 1 minute to check the return amount.

REFERENCE EXAMPLE 1 To 5500 parts by weight of an aqueous solution of sodium acrylate having a neutralization rate of 75 mol% (monomer concentration: 33%), 5.00 parts by weight of polyethylene glycol diacrylate (average number of moles of ethylene oxide added: 8) A portion was dissolved to prepare a reaction solution. Next, this reaction solution was degassed for 30 minutes under a nitrogen gas atmosphere. Next, the reaction solution was supplied to a reactor formed by attaching a lid to a jacketed stainless steel double-armed kneader having two sigma-type blades and having an internal volume of 10 L, and while maintaining the reaction solution at 30 ° C., the system was purged with nitrogen. The gas was replaced. Subsequently, while stirring the reaction solution, 2.46 parts by weight of sodium persulfate and 0.10 parts by weight of L-ascorbic acid were added, and polymerization started about 1 minute later. Then, polymerization was carried out at 30 ° C. to 80 ° C., and 60 minutes after the initiation of the polymerization, the hydrogel polymer was taken out. The obtained hydrogel polymer was subdivided into a diameter of about 5 mm. The finely divided hydrogel polymer was spread on a 50-mesh wire net and dried with hot air at 150 ° C. for 90 minutes. Next, the dried product was pulverized using a vibration mill and further classified with a 20-mesh wire net to obtain an irregularly crushed water-absorbent resin precursor (a) having an average particle size of 280 μm.

The obtained water-absorbent resin precursor (a) was composed of 100 parts by weight of propylene glycol, 0.05 parts by weight of ethylene glycol diglycidyl ether, 3 parts by weight of water, and 1 part by weight of isopropyl alcohol. The surface crosslinking agent was mixed. The mixture was heated at 210 ° C. for 45 minutes to obtain a water-absorbent resin (1). This water-absorbent resin (1) has an absorption capacity of 32 (g / g) and an absorption capacity under pressure of 3
6 (g / g), water absorption rate was 32 seconds.

Reference Example 2 75 mol% in Reference Example 1
The monomer concentration of the aqueous solution of sodium acrylate having a neutralization rate of 38% was set to 38%, the cross-linking agent polyethylene glycol diacrylate was changed to trimethylolpropane triacrylate to 1.75 g, and the grinding conditions of the vibration mill were changed.
An amorphous crushed water-absorbent resin precursor (b) having an average particle size of 350 μm was obtained. A surface cross-linking agent consisting of 1 part by weight of propylene glycol, 0.05 part by weight of ethylene glycol diglycidyl ether, 3 parts by weight of water, and 1 part by weight of isopropyl alcohol is mixed with 100 parts by weight of the water absorbent resin precursor (b). did. The mixture was heated at 210 ° C. for 40 minutes to obtain a water-absorbent resin (2). This water-absorbent resin (2) has an absorption capacity of 30 (g / g) and an absorption capacity under pressure of 33.
(g / g) and the water absorption rate was 44 seconds.

[Reference Example 3] The amount of the crosslinking agent trimethylolpropane triacrylate in Reference Example 2 was changed to 3.50 g, and the pulverization conditions of the vibration mill were changed to obtain an amorphous crushed water-absorbent resin having an average particle size of 410 μm. A precursor (c) was obtained. A surface cross-linking agent composed of 0.5 parts by weight of glycerin, 2 parts by weight of water, and 0.5 parts by weight of isopropyl alcohol was mixed with 100 parts by weight of the water absorbent resin precursor (c). 210 above mixture
By heating at 50 ° C. for 50 minutes, a comparative water absorbent resin (1) was obtained. The absorption capacity of this comparative water absorbent resin (1) is
The absorption capacity under pressure was 30 (g / g), the absorption capacity under pressure was 29 (g / g), and the water absorption rate was 60 seconds.

REFERENCE EXAMPLE 4 In the reference example 2, the conditions of the vibration mill were further changed to obtain an irregularly crushed water-absorbent resin precursor (c) having an average particle size of 120 μm. A surface cross-linking agent composed of 1 part by weight of glycerin, 2 parts by weight of water, and 1 part by weight of isopropyl alcohol was mixed with 100 parts by weight of the water absorbent resin precursor (c). The mixture was heat-treated at 210 ° C. for 40 minutes to obtain a comparative water-absorbent resin (2). The absorption capacity of this comparative water absorbent resin (2) was 29 (g / g), the absorption capacity under pressure was 27 (g / g), and the water absorption rate was 15 seconds.

[Reference Example 5] The water-absorbent resin precursor (a) obtained in Reference Example 1 was used as a comparative water-absorbent resin (3), and its physical properties were measured. The absorption capacity was 41 (g / g). The absorption capacity under pressure was 9 (g / g), and the water absorption rate was 36 seconds.

Example 1 A water-absorbing agent (1) was obtained by mixing 100 parts by weight of the water-absorbing resin (1) obtained in Reference Example 1 with 2 parts by weight of a 10% aqueous solution of benzalkonium chloride as an antibacterial agent. .
Table 1 summarizes various physical properties of the water absorbing agent (1).

Example 2 An antibacterial agent having 100 parts by weight of the water-absorbent resin (1) obtained in Reference Example 1 and benzalkonium chloride supported on a sparingly soluble phosphate (Lasa Industries Co., Ltd., Lasap
QP) (1.0 part by weight) was mixed to obtain a water absorbing agent (2). Table 1 similarly summarizes various physical properties of the water absorbing agent (2).

Example 3 100 parts by weight of the water-absorbent resin (2) obtained in Reference Example 2 was mixed with 2 parts by weight of a 10% aqueous solution of chlorohexidine gluconate as an antibacterial agent, and then silicon dioxide (Nippon Aerosil) was used as an inorganic powder. Aerosil 20
0) was added in an amount of 0.5 part by weight to obtain a water absorbing agent (3). Water absorbing agent (3)
Are summarized in Table 1.

Example 4 100 parts by weight of the water-absorbent resin (2) obtained in Reference Example 2 was mixed with 5 parts by weight of a 10% aqueous solution of polyhexamethylenebiguanidine hydrochloride as an antibacterial agent. I got Table 1 similarly summarizes various physical properties of the water absorbing agent (4).

Example 5 0.7 part by weight of a 30% aqueous solution of didecyldimethylammonium gluconate as an antibacterial agent was mixed with 100 parts by weight of the water-absorbent resin (2) obtained in Reference Example 2, and I got Table 1 similarly summarizes various physical properties of the water absorbing agent (5).

Comparative Example 1 100 parts by weight of the comparative water-absorbing resin (1) obtained in Reference Example 3 was mixed with 2 parts by weight of a 10% aqueous solution of benzalkonium chloride as an antibacterial agent. ) Got. Table 1 summarizes various physical properties of the comparative water absorbing agent (1).

Comparative Example 2 100 parts by weight of the comparative water-absorbent resin (1) obtained in Reference Example 3 was mixed with 2 parts by weight of a 10% aqueous solution of chlorohexidine gluconate as an antibacterial agent. I got Table 1 summarizes various physical properties of the comparative water absorbing agent (2).

Comparative Example 3 100 parts by weight of the comparative water-absorbing resin (2) obtained in Reference Example 4 was mixed with 2 parts by weight of a 10% aqueous solution of benzalkonium chloride as an antibacterial agent. ) Got. Table 1 summarizes various physical properties of the comparative water absorbing agent (3).

Comparative Example 4 100 parts by weight of the comparative water-absorbent resin (3) obtained in Reference Example 5 was mixed with 2 parts by weight of a 10% aqueous solution of benzalkonium chloride as an antibacterial agent. )
I got Table 1 summarizes various physical properties of the comparative water absorbing agent (3).

Comparative Example 5 The comparative water absorbing resin (1) obtained in Reference Example 3 was used as a comparative water absorbing agent (5). Table 1 summarizes various physical properties of the comparative water absorbing agent (5).

Example 6 50 parts by weight of the water-absorbing agent (1) obtained in Example 1 and 50 parts by weight of ground wood pulp were dry-mixed using a mixer. Next, the resulting mixture was air-formed on a wire screen formed into a 400 mesh (mesh size: 38 μm) using a batch-type air-forming device to form a web having a size of 120 mm × 400 mm. . Further, the web was pressed at a pressure of 2 kg / cm2 for 5 seconds to obtain an absorbent having a basis weight of about 0.047 g / cm2.

Subsequently, a back sheet (liquid-impermeable sheet) made of liquid-impermeable polypropylene and having a so-called leg gather, the above-described absorber, and a top sheet made of liquid-permeable polypropylene (liquid-permeable polypropylene) Sheets) were adhered to each other in this order using a double-sided tape, and two so-called tape fasteners were attached to the adhered product, thereby obtaining an absorbent article (that is, a paper diaper) (1). The weight of this absorbent article (1) is 46 g
Met.

The above-mentioned absorbent article (1) was used overnight as a monitor for a one-year-old girl and collected the next day. Absorber part (so-called core part) consisting of water absorbent and wood pulp
Cut into a size of 5 x 20 cm, put in a sterilized beaker, pour 200 ml of sterilized saline, and stir at 37 ° C for 2 hours.
Let stand for hours. Two hours later, the supernatant was sampled, diluted with sterile physiological saline if necessary, and 100 µl of the diluted solution was applied to an agar medium. After culturing overnight at 37 ° C., the number of colonies was counted, and the number of bacteria propagated was determined by multiplying the dilution ratio. The viable cell count in the core was 2 × 10 4 cells / ml.

Comparative Example 6 A comparative absorbent article (1) was obtained in the same manner as in Example 6, except that the absorbent used for the absorbent article was changed to the comparative absorbent (3). The viable count of the bacteria in the core was 6 × 10 6 / ml.

Comparative Example 7 In Comparative Example 6, the absorbent used for the absorbent article was changed to the comparative water absorbent (5) to obtain a comparative absorbent article (2), and the same operation was performed. The viable count of the bacteria in the core was 1 × 10 9 / ml.

[0087]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a measuring device used for measuring an absorption capacity under pressure, which is one of the properties exhibited by a water absorbing agent (water absorbing resin).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Balance 2 Container 3 External air suction pipe 4 Conduit 5 Measurement part 6 Glass filter 7 Filter paper 8 Support cylinder 9 Wire mesh 10 Weight 11 Physiological saline

Claims (8)

[Claims] Claims: 1. An antimicrobial agent containing an absorption capacity under pressure of 25 (g / g).
A water-absorbing agent having a water absorption speed of 20 seconds or more and 50 seconds or less. 2. The water-absorbing agent according to claim 1, wherein the antibacterial agent is water-soluble or water-dispersible. 3. The water absorbing agent according to claim 1, wherein the antibacterial agent is a quaternary ammonium salt compound and / or a biguanide compound. 4. The water-absorbing agent according to claim 1, wherein the antibacterial agent is carried on a powder. 5. The water absorbing agent according to claim 1, wherein the powder is a sparingly soluble phosphate. 6. An antibacterial agent is added in an amount of 0.001 to 100 parts by weight of the water absorbing agent.
2. The water-absorbing agent according to claim 1, wherein the amount is in the range of 5 to 5 parts by weight. 7. A method for producing a water-absorbing agent, comprising adding an antimicrobial agent to a water-absorbing resin having an absorption capacity under pressure of 25 (g / g) or more and a water absorption speed of 20 seconds to 50 seconds. 8. An absorbent layer containing an absorbent having a weight ratio α of the water-absorbent resin to the total amount of the water-absorbent resin and the fiber substrate of 0.3 or more, a liquid-permeable topsheet, and a liquid-impermeable backside. An absorbent article comprising a sheet, which contains an antibacterial agent, has an absorption capacity under pressure of 25 (g / g) or more, and has a water absorption rate of 20 seconds or more.
An absorbent article comprising a water absorbing agent for 0 seconds or less.