JP2003088551A - Absorber and absorptive article using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absorber capable of attaining a reduction in thickness without causing a problem in actual use and an absorptive article using it. SOLUTION: This absorber comprises a water absorptive resin in which the pressure water absorption amount of artificial urine after 30 seconds from water absorption start is 10 g/g or less, and the amount of pressure water absorption of artificial urine after 30 minutes from water absorption start is 20 g/g or more, and a hydrophilic fiber. The water absorptive resin is subjected to hydrophobic treatment, and preferably subjected to surface crosslinking. In this absorber, the ratio of the water absorptive resin is set to 30 wt.% or more and less than 100 wt.% of the total weight of the absorber. The absorber is retained between a liquid permeable sheet and a liquid impermeable sheet to constitute the absorptive article.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an absorbent body used for sanitary materials such as disposable diapers, incontinence pads and sanitary napkins, and absorbent articles using the same.

[0002]

2. Description of the Related Art Absorbent articles such as disposable diapers, incontinence pads, sanitary napkins and the like have a flexible liquid-permeable sheet placed on the side contacting the body and a liquid-impermeable sheet placed on the opposite side in contact with the body. It has a structure in which an absorbent body that absorbs and holds an aqueous liquid such as urine or body fluid is held between the absorbent sheet and the elastic sheet.

The absorbent body is composed of hydrophilic fibers such as cotton-like pulp obtained from wood and a water-absorbent resin. The aqueous liquid passes through the liquid-permeable sheet made of a non-woven fabric or the like and is absorbed by the absorber. The absorbed aqueous liquid is temporarily retained by the hydrophilic fibers and transferred to and retained by the water absorbent resin.

The hydrophilic fiber and the water absorbent resin in the absorbent body have different roles in absorbing and retaining the aqueous liquid.

First, the hydrophilic fiber has a feature that it has a small amount of water absorption per unit amount and easily releases the absorbed aqueous liquid when pressure is applied, but has a very high water absorption rate and good liquid diffusion property. There is. Therefore, the hydrophilic fibers have a role of retaining the aqueous liquid until the water-absorbent resin absorbs the aqueous liquid and diffusing the aqueous liquid in the absorber. Furthermore, the swollen water-absorbent resin is also deformed to close the gaps between the particles and prevent gel blocking which impedes the flow of liquid through the gaps between the particles.

On the other hand, the water-absorbent resin is characterized by a large amount of water absorption per unit amount. Therefore, the water absorbent resin has a role of absorbing and holding the aqueous liquid held and diffused by the hydrophilic fibers.

Due to such a difference in characteristics, the ratio of the hydrophilic fiber and the water-absorbent resin in the absorber is such that the absorption of the aqueous liquid
It is a factor that greatly affects the water absorption characteristics of the absorber, such as diffusivity and the amount of reversion. That is, when the ratio of the hydrophilic fibers is large, the absorber has a good diffusibility of the aqueous liquid, but has a small water absorption amount and a large amount of reversion. vice versa,
When the ratio of the water-absorbent resin is large, the amount of water absorption is large, and the amount of reversion is small, but gel blocking due to the water-absorbent resin is likely to occur, so that the diffusibility of the aqueous liquid deteriorates,
The absorber cannot be used effectively.

In recent years, absorbent articles such as disposable diapers, incontinence pads and sanitary napkins have been made thinner. That is, in the absorbent body composed of the hydrophilic fiber and the water absorbent resin,
By reducing the proportion of hydrophilic fibers that are bulky and have a low ability to retain an aqueous liquid, and increase the proportion of a water absorbent resin that is low in volume and has a high ability to retain an aqueous liquid, the water absorption of the absorbent article is reduced. Without making it thinner.

[0009]

However, if the proportion of the water-absorbent resin in the absorbent is increased to make the absorbent article thinner, gel blocking is likely to occur relatively early from the start of water absorption for the reasons described above. However, the diffusivity of the aqueous liquid is deteriorated, and the absorber is not effectively used, and the aqueous liquid is absorbed only in a small area of the absorber. Therefore, in an actual use state, the total amount of the aqueous liquid that can be absorbed by the absorber becomes small, so that there is a problem that the amount of reversion increases without being completely absorbed, and urine leaks.

Therefore, it is an object of the present invention to provide an absorber that can be made thinner without causing problems in actual use and an absorbent article using the same.

[0011]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that the amount of pressurized water absorption at the initial stage of water absorption and the amount of pressurized water absorption at the latter stage of water absorption, and the water absorption of the absorbent article. Focusing on the relationship with the characteristics, the absorption of water under pressure at the beginning of water absorption is below a specific value, and the absorption of water under pressure at a later stage of water absorption is greater than a specific value, and the absorbent contains a hydrophilic fiber, The inventors have found that the above problems can be solved and have completed the present invention.

That is, according to the present invention, 30 times from the start of water absorption.
A water absorbent resin having a pressurized water absorption of 10 g / g or less of artificial urine after 20 seconds and a pressurized water absorption of 20 g / g or more of artificial urine after 30 minutes from the start of water absorption, and a hydrophilic fiber An absorber is provided.

The water-absorbent resin used in the present invention has an artificial urine pressurized water absorption amount of 5 g / g or less 30 seconds after the start of water absorption, and an artificial urine pressurized water absorption amount of 30 g / g after 30 minutes from the start of water absorption. The amount is preferably g or more, and the saturated water absorption amount with respect to physiological saline is preferably 40 g / g or more.

The weight average particle diameter of the water absorbent resin used in the present invention is preferably 200 to 600 μm.

Further, the water-absorbent resin used in the present invention is preferably subjected to a hydrophobic treatment, and in addition to the hydrophobic treatment, surface cross-linking is preferable.

In the absorber of the present invention, the proportion of the water-absorbent resin is 30% by weight or more and 100% by weight of the total weight of the absorber.
The range is preferably less than. On the other hand, the absorbent article of the present invention, between the liquid permeable sheet and the liquid impermeable sheet,
It is characterized by holding the above-mentioned absorber.

In the absorbent article (absorbent body) of the present invention, the water-absorbent resin having the above-mentioned characteristics is used. In the actual use condition, the absorbent article has excellent diffusibility and suppresses the amount of reversion, and the absorbent article. It becomes possible to achieve a thinner absorber.

That is, the hydrophilic fiber has a very high water absorption rate of the aqueous liquid and is excellent in diffusibility but has a low retention capacity, while the water absorbent resin is excellent in the retention capability of the aqueous liquid, but the diffusibility is high. Inferior to. Therefore, it is preferable that the hydrophilic fiber absorbs the aqueous liquid and diffuses it, especially in the initial stage when the absorbent article absorbs the aqueous liquid, and the water-absorbent resin does not hinder the absorption and diffusion functions of the hydrophilic fiber as much as possible. Is desirable. Since the water-absorbent resin used in the present invention has a low initial absorption rate, the hydrophilic fiber is used to widely diffuse the aqueous liquid in the initial absorption stage, and then the aqueous liquid is rapidly absorbed from the hydrophilic fiber. . Therefore, when the absorbent article absorbs the aqueous liquid, the rapid absorption / diffusion function of the hydrophilic fiber and the high retention capacity of the water absorbent resin for the aqueous liquid can be effectively utilized. As a result, the absorbent article (absorbent body) has excellent performance (water absorption property) such as very high liquid diffusivity and water absorption,
It is possible to reduce the thickness of the absorbent article (absorbent body) while suppressing the occurrence of problems in actual use.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The absorbent body of the present invention and an absorbent article using the same will be described below. Note that examples of the absorbent article include a diaper, an incontinence pad, a sanitary napkin, and the like, but the present invention is not limited to these.

The absorbent article of the present invention comprises a liquid permeable sheet (top sheet) capable of passing an aqueous liquid,
It has a structure in which an absorber that absorbs / holds the aqueous liquid is held between the liquid impermeable sheet (back sheet) that does not pass the aqueous liquid. The liquid permeable sheet is
The liquid-impermeable sheet is arranged on the side that contacts the body, and the liquid-impermeable sheet is arranged on the side that does not contact the body.

Examples of the liquid permeable sheet include, but are not limited to, a nonwoven fabric made of polyethylene, polypropylene, polyester, polyamide or the like, or a porous synthetic resin sheet.

Examples of the liquid impermeable sheet include, but are not limited to, synthetic resin films made of polyethylene, polypropylene, polyvinyl chloride, etc., and films made of a composite material of these synthetic resins and nonwoven fabric. Absent.

The absorbent body of the present invention is composed of hydrophilic fibers and a water absorbent resin. The proportion of the water-absorbent resin in the absorbent is 30% by weight or more and less than 100% by weight, preferably 4% by weight of the total weight of the absorbent so as to achieve a thin absorbent article.
0% by weight or more and less than 100% by weight, more preferably 50
The amount is not less than 100% by weight and most preferably not less than 100% by weight. As the structure of the absorbent body, for example, a mixing structure in which a water absorbent resin and hydrophilic fibers are uniformly blended, a sandwich structure in which a water absorbent resin is held between layered hydrophilic fibers, or a water absorbent resin and hydrophilic fibers are used. Examples include, but are not limited to, tissue wrapped structures. The absorbent body of the present invention may include synthetic fibers as a reinforcing material.

Known hydrophilic fibers include cellulosic fibers such as cotton-like pulp, mechanical pulp, chemical pulp and semi-chemical pulp obtained from wood, and artificial cellulose fibers such as rayon and acetate. It may also contain synthetic fibers such as polyamide, polyester and polyolefin. The hydrophilic fiber is not limited to these.

The water absorbent resin used in the present invention has a pressurized water absorption of artificial urine of 30 g 30 seconds after the start of water absorption.
g or less, preferably 5 g / g or less, more preferably 0.1 to 5 g / g, and the pressurized water absorption of artificial urine 30 minutes after the start of water absorption is 20 g / g or more, preferably 3
It is 0 g / g or more, more preferably 30 to 70 g / g is used. The water-absorbent resin used in the present invention has a saturated water absorption amount of 40 g / g or more relative to physiological saline.
Preferably 40-100 g / g, more preferably 40-
90 g / g, more preferably 40 to 80 g / g. This is because if the pressurized water absorption amount or the saturated water absorption amount after a lapse of a certain time from the start of water absorption is too low, the absorption amount of the absorber becomes too low, and the object of the present invention cannot be achieved.

Here, the pressurized water absorption amount for artificial urine and the saturated water absorption amount for physiological saline in the present invention refer to those measured by the method described later. The artificial urine referred to in the present invention is 1 part by weight of NaCl, 0.03 parts by weight of CaCl ₂ .2H ₂ O, MgCl ₂ and 100 parts by weight of distilled water,
The ₂ · 6H ₂ O refers to one obtained by dissolving 0.06 parts by weight, and the physiological saline in the present invention refers to a 0.9 wt% aqueous sodium chloride solution.

The water-absorbent resin is mainly used for absorbent articles such as paper diapers, and it is necessary to absorb a large amount of aqueous liquid without inhibiting the diffusion of the aqueous liquid in the composite with hydrophilic fibers. . Further, when the absorbent article is used, some load is applied to the water absorbent resin, so the water absorbent resin used for the absorbent article has the above-mentioned performance under a certain amount of pressure. Required.

On the other hand, in the water absorbent resin used in the present invention, the amount of water absorbed under pressure 30 seconds after the start of water absorption is relatively small, so gel blocking is less likely to occur, and the diffusion of the aqueous liquid is dominant immediately after the start of water absorption. It has a performance that water absorption becomes dominant 30 minutes after the start of water absorption. Therefore, the absorbent body of the present invention is configured based on the evaluation in consideration of the composite state of the water absorbent resin and the hydrophilic fiber,
It has excellent diffusivity and is extremely practical with suppressed reversion. Further, as a result of having such characteristics, when the absorbent body of the present invention is used in an absorbent article, the aqueous liquid can be sufficiently diffused and absorbed even if the ratio of the water-absorbent resin is increased. It is possible to achieve a thin absorbent article while avoiding problems.

The water-absorbent resin used in the present invention preferably has a weight-average particle size of 200 to 600 μm, and 300 to 600 μm, in order to suppress the occurrence of gel blocking and the feeling of foreign matter felt by the user. The range of 600 μm is more preferable. When the weight average particle diameter of the water-absorbent resin is smaller than 200 μm, the small particles are present in a large proportion, and not only the handling property of the powder is deteriorated due to powder standing but also gel blocking is likely to occur. Not preferred as it is difficult to achieve. On the other hand, when the weight average particle diameter of the water-absorbent resin is larger than 600 μm, when the water-absorbent resin is used in an absorbent article such as a diaper, the user may feel a foreign substance and comfortably use the absorbent article. It is not preferable because it cannot be done.

The water absorbent resin used in the present invention includes:
Examples thereof include cross-linked polyacrylic acid partially neutralized products, neutralized products of starch-acrylic acid graft polymers, and hydrolyzates of starch-acrylonitrile graft polymers.

One such water-absorbent resin is selected from unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid and itaconic acid, or neutralized products thereof. It can be obtained by polymerizing or copolymerizing the above monomers, and then subjecting the polymer to operations such as pulverization and classification as necessary to adjust the weight average particle diameter to a desired value. As the monomer, acrylic acid and its neutralized product are preferable because they are inexpensive and easily available.

The polymerization method which can be adopted as the method for producing the water-absorbent resin used in the present invention is not particularly limited, and various generally known polymerization methods such as the reverse phase suspension polymerization method and the aqueous solution polymerization method are used. Legal can be adopted.

1 of production of water-absorbent resin used in the present invention
An exemplary reverse phase suspension polymerization method is described below.

In the reverse phase suspension polymerization method, polymerization is carried out in the presence of a dispersion stabilizer in a state where an aqueous monomer solution is dispersed in an organic solvent, for example, by using a polymerization initiator.

A hydrocarbon solvent is used as the organic solvent. The hydrocarbon solvent used here is an aliphatic hydrocarbon solvent or an alicyclic hydrocarbon solvent. Examples of the aliphatic hydrocarbon solvent include n-hexane and n-heptane. Examples of the alicyclic hydrocarbon solvent include cyclopentane, methylcyclopentane, cyclohexane and methylcyclohexane.
Among these hydrocarbon solvents, preferable ones are n-hexane, n-heptane, and cyclohexane, which have industrially constant quality, are easily available, and are inexpensive. The hydrocarbon solvent may be used as a mixture of two or more kinds.

Examples of the monomer aqueous solution include unsaturated carboxylic acid aqueous solutions. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, β-hydroxyacrylic acid, β-acryloxypropionic acid and salts thereof. The concentration of the monomer in the aqueous monomer solution is, for example, 10% by weight to saturated weight%, and more preferably 25% by weight to saturated weight%.

Examples of the salt constituting the unsaturated carboxylic acid salt include an alkali metal salt, an alkaline earth metal salt and an ammonium salt, but sodium is particularly preferable.
Alkali metal salts such as potassium are used.

The unsaturated carboxylic acid aqueous solution may contain a copolymerization component other than the unsaturated carboxylic acid monomer. Examples of the copolymerization component include (meth) acrylamide, N
-Nonionic hydrophilic group-containing monomer such as substituted (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethyleneglycol (meth) acrylate, polyethyleneglycol (meth) acrylate An amino group-containing unsaturated monomer such as N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide or their 4
Examples thereof include graded products, but the copolymerization component is not particularly limited. In addition, starch, cellulose and derivatives thereof, water-soluble polyacrylic acid (salt) and cross-linked products thereof, and hydrophilic polymers such as polyvinylpyrrolidone and polyvinyl alcohol may be added to these unsaturated carboxylic acid solutions. Good.

Examples of the dispersion stabilizer include nonionic surfactants such as sorbitan fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, sorbitol fatty acid ester, polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether. . Two or more kinds of such dispersion stabilizers may be mixed and used.

A polymer dispersion aid may be used together with the dispersion stabilizer. These may be used in combination with the surfactant before the polymerization or may be added after the polymerization. As the polymer dispersion aid, for example, ethyl cellulose, ethyl hydroxyethyl cellulose, oxidation-modified polyethylene, maleic anhydride-modified polyethylene, maleic anhydride-modified polybutadiene, maleic anhydride-modified EPDM (ethylene propylene diene terpolymer), etc. are used. .

The amount of the dispersion stabilizer and / or polymer dispersion aid used is usually 0.1 to 5% by weight, preferably 0.2 to 3% by weight, of the unsaturated carboxylic acid aqueous solution. If the amount used is less than 0.1% by weight, the dispersion will be insufficient. On the contrary, even if it exceeds 5% by weight, the effect corresponding to it cannot be obtained.

As the polymerization initiator, generally used water-soluble radical polymerization initiators such as potassium persulfate, ammonium persulfate and sodium persulfate are suitable, and they are used as a redox type polymerization initiator in combination with these. It is also possible. The amount of these polymerization initiators used is preferably in the range of 0.001 mol% to 2 mol% with respect to the monomer, and more preferably in the range of 0.01 mol% to 0.5 mol%.

The polymerization temperature is usually 20 to 110 ° C., preferably 40 to 80 ° C., though it varies depending on the kind of the polymerization initiator used. If the polymerization temperature is lower than 20 ° C,
It is not economical because the polymerization rate decreases and the polymerization time becomes long. On the other hand, when the polymerization temperature is higher than 110 ° C, it is difficult to remove the heat of polymerization and it becomes difficult to carry out a smooth polymerization reaction. .

The water absorbent resin used in the present invention is preferably crosslinked inside by reacting or copolymerizing with a crosslinking agent having a plurality of polymerizable unsaturated groups or a plurality of reactive groups. . Further, the water absorbent resin may be a self-crosslinking type that does not require a crosslinking agent.

Examples of the cross-linking agent include, for example, polymerizable cross-linking agents such as ethylene glycol, propylene glycol,
Di- or tri (meth) acrylic esters of polyols such as trimethylolpropane, glycerin, polyoxyethylene glycol, polyoxypropylene glycol, polyglycerin; reacting the polyols with unsaturated acids such as maleic acid and fumaric acid Unsaturated polyesters obtained by the reaction; bisacrylamides such as N, N'-methylenebis (meth) acrylamide; ditri (meth) acrylic acid esters obtained by reacting polyepoxide with (meth) acrylic acid; tolylenediene Carbamine esters of di (meth) acrylic acid obtained by reacting polyisocyanates such as isocyanate and hexamethylene diisocyanate with hydroxyethyl (meth) acrylate; allylated starch, allylated cellulose, diallylphthalate Over DOO, N, N ', N "- triallyl diisocyanate rate, and divinylbenzene.

Among these, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, propylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, diallyl phthalate, N, N ', N "-triallyl isocyanate Nurate, N, N'-methylenebisacrylamide and the like are usually used.

On the other hand, the cross-linking agent utilizing the reaction with the carboxyl group in the unsaturated carboxylic acid or its polymer is, for example, a diglycidyl ether compound, an isocyanate compound or a haloepoxy compound, among which diglycidyl is particularly preferable. Ether compounds are suitable.

Specific examples of the diglycidyl ether compound include (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, and (poly) glycerin diglycidyl ether. Among them, polyethylene glycol diglycidyl ether is most preferable. Gives good results. Examples of the haloepoxy compound include epichlorohydrin, epibromhydrin, α-methylepichlorohydrin and the like. Examples of the isocyanate compound include 2,4-tolylene isocyanate and hexamethylene diisocyanate. These crosslinking agents may be used alone or in combination of two or more. Among the exemplified compounds, it is more preferable to use a compound having a plurality of polymerizable unsaturated groups as a crosslinking agent.

The amount of the cross-linking agent that cross-links the inside of the water absorbent resin is 0.001 to 3% by weight, preferably 0.003 to 2% by weight based on the total amount of the monomers used for producing the water absorbent resin.
%, And more preferably 0.005 to 1% by weight. When the amount of the cross-linking agent used is less than 0.001% by weight, the gel strength of the water-absorbent resin at the time of water absorption is lowered and the purpose cannot be achieved. On the other hand, when it exceeds 3% by weight, the water absorption amount is extremely lowered, which is preferable. Absent.

The water-absorbent resin used in the present invention is preferably subjected to a hydrophobic treatment or, in addition to the hydrophobic treatment, surface-crosslinked.

Here, when the hydrophobic treatment is applied, the water-absorbent resin is less likely to swell at the initial water absorption and gel blocking is less likely to occur, so that the diffusibility of the aqueous liquid is improved. On the other hand, surface cross-linking means cross-linking the surface layer of the water-absorbent resin particles to increase the degree of cross-linking of the surface layer as compared with the inner layer. Therefore, the particles subjected to surface cross-linking have higher surface layer strength than those not subjected to surface cross-linking, and thus are less likely to be deformed even when a liquid is taken into the particles, and gel blocking is less likely to occur. As a result, the diffusivity at the time of absorbing water can be improved, the absorber can be effectively used, and the amount of reversion can be reduced. Therefore, if hydrophobic treatment or surface cross-linking is performed, the diffusion of the liquid can be dominated at the initial stage of water absorption, and the pressurized water absorption amount and the saturated water absorption amount after a certain time (for example, 30 minutes) has elapsed from the water absorption start. It will be possible to secure a large amount.

The hydrophobic treatment may be carried out, for example, by dissolving a hydrophobic material in various solvents, or by melting it by heating, spraying and drying the water-absorbent resin for coating, or during the production of the water-absorbent resin. It can be performed by polymerizing and coating in the presence of a hydrophobic material. In the present invention, the hydrophobic treatment method is not limited to these.

The amount of the hydrophobic material added varies depending on the type, but is 0.001 to 100 parts by weight of the water absorbent resin.
A range of 10 parts by weight is preferred. If the amount used is less than 0.001 part by weight, the effect will be insufficient, and conversely, if it exceeds 10 parts by weight, the corresponding economical effect will not be seen.

As the hydrophobic material, a material substantially insoluble in water, for example, n-dodecane, n-hexadecane, n-
Higher aliphatic hydrocarbons such as heptadecane, dodecane-1-
Higher aliphatic compounds such as higher aliphatic alcohols such as oat, hexadecan-1-ol, sorbitan fatty acid ester, polyglycerin fatty acid ester, sorbitol fatty acid ester, sucrose fatty acid ester; lauric acid amide, oleic acid Higher fatty acid amides such as amide and erucic acid amide; polyethylene, polypropylene, ethylene / vinyl acetate copolymer, oxidation modified polyethylene, maleic anhydride modified polyethylene, maleic anhydride modified polybutadiene, maleic anhydride modified EP
DM (Ethylene / Propylene / Diene / Terpolymer)
Polyolefins such as nylon; Polyamides such as nylon; Polyesters such as polyethylene terephthalate; Cellulose derivatives such as cellulose acetate, cellulose propionate, cellulose butyrate, ethyl cellulose, benzyl cellulose, ethyl hydroxyethyl cellulose; hydrophobic such as hydrophobic silica Inorganized powders and the like are included. These may be used alone or 2
It is also possible to use a combination of more than one type. Among them, fatty acid esters are preferable, and especially HLB is 5 or less,
Fatty acid esters having an HLB of 4 or less, and more preferably an HLB of 3 or less are preferred.

As the surface cross-linking agent, one capable of reacting with the carboxyl group in the water absorbent resin is used. For example,
(Poly) ethylene glycol diglycidyl ether,
Epoxy compounds such as (poly) glycerol polyglycidyl ether, (poly) propylene glycol diglycidyl ether, glycidol; halogenated epoxy compounds such as epichlorohydrin, epibromhydrin, α-methylepichlorohydrin; (poly) Ethylene glycol, (poly) propylene glycol, 1,3-propanediol, (poly) glycerin, diols, pentanediols, hexanediols, cyclohexanediols, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, Polyhydric alcohol compounds such as pentaerythritol and sorbitol; ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexami , Polyethylenimine, polyamide polyamine and other polyvalent amine compounds; 2,4-tolylene diisocyanate, hexamethylene diisocyanate and other polyvalent isocyanate compounds; 1,2-ethylenebisoxazoline and other polyvalent oxazoline compounds; γ-glycidoxy Silane coupling agents such as propyltrimethoxysilane and γ-aminopropyltrimethoxysilane; hydroxides such as aluminum, magnesium and titanium, and polyvalent metal compounds such as chlorides, and the like, but are not particularly limited. Absent

Of the above surface cross-linking agents, epoxy compounds and polyhydric alcohol compounds are more preferably used.
These surface cross-linking agents may be used alone or in combination of two or more.

The amount of the surface cross-linking agent used is 0.01 to 5% by weight, preferably 0.02, based on the total amount of the above monomers.
-4% by weight, more preferably 0.03-3% by weight. If the amount of the cross-linking agent used is less than 0.01% by weight, the gel strength of the water-absorbent resin at the time of absorbing water may be lowered and the purpose may not be achieved. On the other hand, if it is more than 5% by weight, the water absorption amount may be extremely lowered, which is not preferable.

The timing of adding the surface cross-linking agent is not particularly limited as long as it is after the polymerization of the monomer, but it is preferable to add it in the presence of water. Regarding the amount of water, 1 to 300 parts by weight, relative to 100 parts by weight of the water-absorbent resin solid content,
It is preferably 5 to 200 parts by weight.

The surface cross-linking agent may be added, for example, by distilling off a certain amount of water from the water-containing polymer immediately after completion of the polymerization, or by adding the surface cross-linking agent to a water absorbent resin powder in a small amount of water. Examples thereof include a method of uniformly adding the compound by spraying, but the method is not particularly limited.

[0060]

EXAMPLES Hereinafter, the present invention will be described together with Examples and Comparative Examples. Prior to that, a production example of a water absorbent resin used in each Example and Comparative Example will be described, and then each Example and Comparative Example. The measurement method for the measurement items in 1. will be described.

Production Example 1 : 1000 ml equipped with a stirrer, reflux condenser, dropping funnel, thermometer and nitrogen gas introducing pipe
Add 500 n-heptane to a 5-necked cylindrical round bottom flask.
ml was added. To this, 1.38 g of hexaglyceryl monobehenylate having an HLB of 13.1 was added and dispersed,
After the temperature was raised to 50 ° C. to dissolve it, it was cooled to 30 ° C.

On the other hand, a 500 ml Erlenmeyer flask was prepared, and 92 g of 80 wt% acrylic acid aqueous solution was added. While cooling with ice from the outside, 102.2 g of a 30 wt% sodium hydroxide aqueous solution was added dropwise to neutralize 75 mol% to prepare a partially neutralized acrylic acid aqueous solution. Furthermore, 0.46 g of hydroxyethyl cellulose was added,
It was dissolved by stirring for 2 hours. Then, 50.3 g of water and 0.11 g of potassium persulfate as a polymerization initiator were added to obtain a monomer aqueous solution.

Next, the above-mentioned aqueous monomer solution was added to and dispersed in the above-mentioned five-necked cylindrical round-bottomed flask under agitation, the system was sufficiently replaced with nitrogen, and then the temperature was raised to 70 ° C. The polymerization reaction was carried out for a time. After the completion of the polymerization, water was distilled off from the hydrous gel-like substance by azeotropic distillation with n-heptane. To the dehydrated hydrated gel-like substance, 92.0 mg of ethylene glycol diglycidyl ether dissolved in 4.6 g of water was added, and the mixture was heated at 80 ° C. for 2 hours.
Held for hours. Then, 0.92 g of powdery ethyl cellulose dispersed in 50 ml of n-heptane was added, and the mixture was further held for 1 hour. Then, excess water and n-heptane were removed by distillation, dried, and classified with a 850 μm sieve to obtain a water absorbent resin (A).

Production Example 2 : A water absorbent resin (B) was obtained in the same manner as in Production Example 1 except that 0.92 g of powdered maleic anhydride modified polyethylene was used in place of ethyl cellulose.

Production Example 3 : HL in place of ethyl cellulose
A water absorbent resin (C) was obtained in the same manner as in Production Example 1 except that 0.92 g of sorbitan trioleate having B of 1.8 was used.

Production Example 4 : 1000 ml equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer and a nitrogen gas introducing pipe
Add 500 n-heptane to a 5-necked cylindrical round bottom flask.
ml was added. To this, 1.38 g of hexaglyceryl monopehenylate having an HLB of 13.1 was added and dispersed,
After the temperature was raised to 50 ° C. to dissolve it, it was cooled to 30 ° C.

On the other hand, two 500 ml Erlenmeyer flasks were prepared, and first, 92 g of an 80 wt% acrylic acid aqueous solution was added. While cooling with ice from the outside, 102.2 g of a 30 wt% sodium hydroxide aqueous solution was added dropwise to neutralize 75 mol% to prepare a partially neutralized acrylic acid aqueous solution. Further, 50.3 g of water and 0.11 g of potassium persulfate as a polymerization initiator were added to prepare a monomer aqueous solution (a) for the first stage polymerization. Next, in another 500 ml Erlenmeyer flask, 119.1 g of 80 wt% acrylic acid aqueous solution was added.
Then, while cooling as described above, 132.2 g of 30 wt% sodium hydroxide aqueous solution was added dropwise to neutralize 75 mol%, and further, 27.4 g of water and potassium persulfate 0.1
4 g was added, and this was used as a monomer aqueous solution (b) for the second stage polymerization.

Next, in the above five-necked cylindrical round bottom flask,
The total amount of the monomer aqueous solution (a) for the first-stage polymerization was added and dispersed under stirring, the system was sufficiently replaced with nitrogen, and then the temperature was raised to 70 ° C. to carry out a polymerization reaction for 1 hour. Then, the polymerization slurry liquid was cooled to 40 ° C., and the monomer aqueous solution (b) for the second stage polymerization was added. After the whole amount was added, the inside of the system was sufficiently replaced with nitrogen again, the temperature was raised to 70 ° C., and the second stage polymerization reaction was carried out for 1 hour. After the completion of the second-stage polymerization, water was distilled off from the hydrous gel together with n-heptane by heating. 211.0 mg of ethylene glycol diglycidyl ether dissolved in 10.5 g of water was added to the dehydrated hydrogel, and the mixture was kept at 80 ° C. for 2 hours. Then, powdered maleic anhydride modified polyethylene dispersed in 50 ml of n-heptane was added to 2.
1 g was added and kept for another 1 hour. Then, excess water and n-heptane are removed by distillation and dried,
A water-absorbent resin (D) was obtained by classification with a 0 μm sieve.

Production Example 5 : A water absorbent resin (E) was obtained in the same manner as in Production Example 4 except that 1.0 g of powdery hydrophobic silica was used in place of the maleic anhydride-modified polyethylene.

Production Example 6 : 1000 ml equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer and a nitrogen gas introducing pipe
Add 500 n-heptane to a 5-necked cylindrical round bottom flask.
ml was added. 0.92 g of sucrose fatty acid ester having an HLB of 3.0 was added to and dispersed in this, and the temperature was raised to 55 ° C. to dissolve it, followed by cooling to 30 ° C.

On the other hand, a 500 ml Erlenmeyer flask was prepared, and 92 g of 80 wt% acrylic acid aqueous solution was added. While cooling with ice from the outside, 102.2 g of a 30 wt% sodium hydroxide aqueous solution was added dropwise to neutralize 75 mol% to prepare a partially neutralized acrylic acid aqueous solution. To this, 0.46 g of hydroxyethyl cellulose was added,
It was dissolved by stirring for 2 hours. Then, 50.3 g of water and 0.11 g of potassium persulfate as a polymerization initiator were added to obtain a monomer aqueous solution.

Next, the above-mentioned aqueous monomer solution was added to and dispersed in a five-necked cylindrical round-bottomed flask under stirring, the system was sufficiently replaced with nitrogen, and the temperature was raised to 70 ° C. for 1 hour. A polymerization reaction was carried out. After the polymerization is completed, the water content of the water-containing gel is n-
It was distilled off by heating together with heptane. 92.0 mg of ethylene glycol diglycidyl ether dissolved in 4.6 g of water was added to the dehydrated hydrous gel, and the mixture was kept at 80 ° C. for 2 hours. Then, excess water and n-heptane were removed by distillation, dried, and classified with a 850 μm sieve to obtain a water absorbent resin (F).

Production Example 7 : 1000 ml equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer and a nitrogen gas introducing pipe
Add 500 n-heptane to a 5-necked cylindrical round bottom flask.
ml was added. 0.92 g of sucrose fatty acid ester having an HLB of 3.0 was added to and dispersed in this, and the temperature was raised to 55 ° C. to dissolve it, followed by cooling to 30 ° C.

On the other hand, two 500 ml Erlenmeyer flasks were prepared, and first, 92 g of 80 wt% acrylic acid aqueous solution was added. While cooling with ice from the outside, 102.2 g of a 30 wt% sodium hydroxide aqueous solution was added dropwise to neutralize 75 mol% to prepare a partially neutralized acrylic acid aqueous solution. Further, 50.3 g of water and 0.11 g of potassium persulfate as a polymerization initiator were added to prepare a monomer aqueous solution (a) for the first stage polymerization. Next, in another 500 ml Erlenmeyer flask, 119.1 g of 80 wt% acrylic acid aqueous solution was added.
Then, while cooling as described above, 132.2 g of 30 wt% sodium hydroxide aqueous solution was added dropwise to neutralize 75 mol%, and further, 27.4 g of water and potassium persulfate 0.1
4 g was added, and this was used as a monomer aqueous solution (b) for the second stage polymerization.

Next, the total amount of the monomer aqueous solution (a) for the first-stage polymerization was added to and dispersed in a five-necked cylindrical round-bottomed flask, and the system was sufficiently replaced with nitrogen. The temperature was raised to 70 ° C. and the polymerization reaction was carried out for 1 hour. Then, the polymerization slurry liquid was cooled to 40 ° C., and the monomer aqueous solution (b) for the second stage polymerization was added. After the whole amount was added, the inside of the system was sufficiently replaced with nitrogen again, the temperature was raised to 70 ° C., and the second stage polymerization reaction was carried out for 1 hour. After the completion of the second-stage polymerization, the water content of the hydrogel was n-
It was distilled off by heating together with heptane. 211.0 mg of ethylene glycol diglycidyl ether dissolved in 10.5 g of water was added to the dehydrated hydrogel, and the mixture was kept at 80 ° C. for 2 hours. Then, excess water and n-heptane were removed by distillation, dried, and classified with a 850 μm sieve to obtain a water absorbent resin (G).

Production Example 8 : As an operation after completion of the second-stage polymerization, 211.0 m of ethylene glycol diglycidyl ether dissolved in 10.5 g of water in a dehydrated hydrous gel-like material.
After adding 2g and holding at 80 ℃ for 2 hours,
The same procedure as in Production Example 7 except that 0.92 g of powdery ethyl cellulose in which 1 n-heptane was dispersed was added and held for 1 hour, and then excess water and n-heptane were removed by distillation and drying. The operation was performed to obtain a water absorbent resin (H).

Production Example 9 : 1000 ml equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer and a nitrogen gas introducing pipe
Add 500 n-heptane to a 5-necked cylindrical round bottom flask.
ml was added. To this, 1.38 g of hexaglyceryl monopehenylate having an HLB of 13.1 was added and dispersed,
After the temperature was raised to 50 ° C. to dissolve it, it was cooled to 30 ° C.

On the other hand, two 500 ml Erlenmeyer flasks were prepared, and first, 92 g of an 80 wt% acrylic acid aqueous solution was added. While cooling with ice from the outside, 102.2 g of a 30 wt% sodium hydroxide aqueous solution was added dropwise to neutralize 75 mol% to prepare a partially neutralized acrylic acid aqueous solution. Further, 50.3 g of water and 0.11 g of potassium persulfate as a polymerization initiator were added to prepare a monomer aqueous solution (a) for the first stage polymerization. Next, in another 500 ml Erlenmeyer flask, 119.1 g of 80 wt% acrylic acid aqueous solution was added.
Then, while cooling as described above, 132.2 g of a 30 wt% sodium hydroxide aqueous solution was added dropwise to neutralize 75 mol%, and further, 27.4 g of water, potassium persulfate 0.14
g was added, and this was added to the aqueous monomer solution (b) for the second stage polymerization.
And

Then, the total amount of the monomer aqueous solution (a) for the first stage polymerization was added to and dispersed in a five-necked cylindrical round-bottomed flask, and the system was sufficiently replaced with nitrogen. The temperature was raised to 70 ° C. and the polymerization reaction was carried out for 1 hour. Then, the polymerization slurry liquid was cooled, and the previously cooled monomer aqueous solution (b) for the second stage polymerization was added. After the entire amount was added, the inside of the system was sufficiently replaced with nitrogen, and then the bath temperature was maintained at 70 ° C. to carry out the second-stage polymerization reaction for 1 hour. After the completion of the second-stage polymerization, water was distilled off from the hydrous gel together with n-heptane by heating. 211.0 mg of ethylene glycol diglycidyl ether dissolved in 10.5 g of water was added to the dehydrated hydrogel.
Hold at 80 ° C. for 2 hours. Then excess water and n-
Heptane was removed by distillation, dried, and classified with a 850 μm sieve to obtain a water absorbent resin (I).

Production Example 10 : 1000 m equipped with stirrer, reflux condenser, dropping funnel, thermometer and nitrogen gas introducing pipe
50 mL of n-heptane was added to a 5-necked, round-bottomed, round-bottomed flask.
0 ml was added. To this, 1.84 g of sorbitan monolaurate having an HLB of 8.7 was added and dispersed, the temperature was raised to 50 ° C. to dissolve, and then the mixture was cooled to 30 ° C.

On the other hand, a 500 ml Erlenmeyer flask was prepared, and 92 g of 80 wt% acrylic acid aqueous solution was added. While cooling with ice from the outside, 102.2 g of a 30 wt% sodium hydroxide aqueous solution was added dropwise to neutralize 75 mol% to prepare a partially neutralized acrylic acid aqueous solution. Furthermore, 50.3 g of water and 0.
11 g was added to obtain an aqueous monomer solution.

Next, the above-mentioned aqueous monomer solution was added to and dispersed in a five-necked cylindrical round-bottomed flask under stirring, the system was sufficiently replaced with nitrogen, and the temperature was raised to 70 ° C. for 1 hour. A polymerization reaction was carried out. After the polymerization is completed, the water content of the water-containing gel is n-
It was distilled off by heating together with heptane. 92.0 mg of ethylene glycol diglycidyl ether dissolved in 4.6 g of water was added to the dehydrated hydrous gel, and the mixture was kept at 80 ° C. for 2 hours. Then, excess water and n-heptane were removed by distillation, dried, and classified with a 850 μm sieve to obtain a water absorbent resin (J).

Pressurized water absorption: Pressurized water absorption after 30 seconds and 30 minutes from the start of water absorption was measured by using a measuring apparatus X having a schematic configuration in FIG.

The measuring apparatus X shown in FIG. 1 comprises a balance 1, a bottle 2 placed on the balance 1, an air suction pipe 3, a conduit 4, a glass filter 5, and a glass filter 5 on the glass filter 5. It is composed of the measuring unit 6 placed. The balance 1 is connected to a computer 7 so that the weight change can be recorded in seconds or minutes. The bottle 2 holds the artificial urine 8 in its inside, and the air suction pipe 3 is put in the opening portion at the top thereof, while the conduit 4 is provided in the body portion.
Is attached. The lower end of the air suction tube 3 is submerged in the artificial urine 8. The diameter of the glass filter 5 is 25
mm. As the glass filter 5, the glass filter No. of Mutual Physics and Chemistry Glass Research Institute was used. 1 (pore size 100 ~
160 μm) was used. The bottle 2 and the glass filter 5 are in communication with each other by the conduit 4. Further, the glass filter 5 is fixed at a position slightly higher than the lower end of the air suction pipe 3. The measuring unit 6 is a cylinder 6
0, a nylon mesh 61 attached to the bottom of the cylinder 60, and a weight 62. The inner diameter of the cylinder 60 is 2 cm. Nylon mesh 61 is 200
It is formed in a mesh (mesh size 75 μm). Then, a predetermined amount of the water absorbent resin 9 is placed on the nylon mesh 61.
Are evenly sprinkled. The weight 62 is placed on the water absorbent resin 9 so that a load of 5 g can be uniformly applied to the water absorbent resin 9.

In the measuring device X having such a structure, first, a predetermined amount of artificial urine 8 and the air suction tube 3 are put in the bottle 2 to prepare for the measurement. As artificial urine 8, distilled water 593
4.6 g, NaCl 60 g, CaCl ₂ .2H ₂ O
1.8g, consists of MgCl ₂ · 6H2O 3.6g,
The one colored with Food Blue No. 1 was used. Then the cylinder 6
0.10 g of the water absorbent resin 9 was evenly spread on the nylon mesh 61 of No. 0, and the weight 62 was placed on the water absorbent resin 9. The measurement part 6 was placed on the glass filter 5 so that the center part thereof coincided with the center part of the glass filter 5.

On the other hand, when the computer 7 connected to the electronic balance 1 is started and water starts to be absorbed continuously,
Based on the value obtained from the balance 1, the reduced weight of the artificial urine 8 in the bottle 2 (the weight of the artificial urine 8 absorbed by the water-absorbent resin 9) Wa (g) is calculated in minutes, preferably seconds. Recorded in. 30 seconds after starting water absorption and 30
The water absorption under pressure of the water-absorbent resin 9 after a minute is calculated by multiplying the weight Wa (g) at each time point by the weight of the water-absorbent resin 9 (0.10
Obtained by dividing by g).

Saturated water absorption : 2.0 g of water-absorbent resin, 50
Saline (0.9 wt% Na in a 0 ml beaker)
Cl aqueous solution), and the mixture was gently stirred for 1 hour to be sufficiently swollen. On the other hand, 75 μm standard sieve (JIS-
The weight Wb (g) of Z8801-1982 was measured, and the aqueous solution containing the swollen gel was filtered through a 75 μm standard sieve. A 75 μm standard sieve was left for 30 minutes in a state where the angle formed with respect to the horizontal was about 30 degrees, and excess physiological saline was removed from the water absorbent resin. The weight Wc (g) of the sieve containing the swollen gel was measured, and the weight Wc
The saturated water absorption was calculated by dividing the value obtained by subtracting the weight Wb (g) of the 75 μm standard sieve from the value (g) by the weight of the water absorbent resin (2.0 g).

Weight average particle diameter : 100 g of the water-absorbent resin was weighed and the weight was defined as the charged amount Wd (g). JIS-Z
8 standard sieves corresponding to 8801-1982 (opening 850
μm, 500 μm, 355 μm, 300 μm, 250 μ
m, 180 μm, 106 μm, stacked in the order of the bottom container), the water-absorbent resin was placed in the top sieve, and the weight of the sieve containing the water-absorbent resin was vibrated for 10 minutes using a low-tap type sieve vibrator. We (g) was measured. The weight ratio of the water-absorbent resin remaining on each sieve is the weight We of the sieve containing the water-absorbent resin.
The weight Wf (g) of the sieve is subtracted from (g) to measure the weight Wg (g) of the water-absorbent resin remaining on the sieve, and then the weight Wf
It was calculated by dividing g (g) by the charged amount Wd (g) and multiplying by 100. Then, the weight of the water-absorbent resin remaining on each sieve was measured, and based on the result, the weight average particle diameter at which the integrated weight becomes 50% by weight of the total weight was calculated by the following formula.

[0089]

[Equation 1]

In the formula, A is the weight sequentially accumulated from the coarser particle size distribution, and the accumulated weight is less than 50% by weight, and 5
It is the integrated value (g) when the integrated value of the point closest to 0% by weight was obtained, and B is the opening (μm) of the knot when the integrated value was obtained. Further, D is the integrated value (g) when the integrated weights are sequentially added from the coarser particle size distribution, and the integrated value of the integrated weight of 50% by weight or more and the point closest to 50% by weight is obtained. Yes, and C is a node opening (μm) when the integrated value is obtained.

Amount of reversion and diffusion length : The amount of reversion and the diffusion length were measured in the state of the absorbent article. The absorbent article is
It was produced by sandwiching the absorbent body with a non-woven fabric having a size of 40 cm × 12 cm and a weight of 1 g, and a polyethylene sheet having the same size and the same weight. The absorbent body was obtained by dry-mixing a water-absorbent resin and crushed pulp (hydrophilic fiber) using a mixer, and had a size of 40 cm × 12 cm and a weight of 1 g.
After spraying on the tissue of No. 1, stack the tissue of the same size and weight into a sheet,
It was manufactured by applying a load of kPa and pressing.

150 ml of artificial urine near the center of the absorbent article
Was poured over 1 minute and left for 5 minutes. Then 10c
Filter paper (Toyo filter paper No. 2) cut into m x 10 cm 20
The sheets were stacked and placed near the center of the absorbent article, and a 3.5 kg weight (bottom surface = 10 cm × 10 cm) was placed on the absorbent article and weighted for 3 minutes. The amount of artificial urine absorbed in the filter paper was measured, and this was used as the amount of reversion. Further, with respect to the artificial urine absorbed in the absorbent article, the spread of the absorbent article in the longitudinal direction was measured, and this was taken as the diffusion length.

Example 1 With respect to the water absorbent resin (A) obtained in Production Example 1, the pressurized water absorption amount after 30 seconds, the pressurized water absorption amount after 30 minutes, the saturated water absorption amount, and The weight average particle diameter was measured. On the other hand, using 8 g of the water-absorbent resin and 18 g of crushed pulp obtained in Production Example 1, the weight was 26 g and the ratio of the water-absorbent resin was 30 g by the method described above.
After producing an absorber having a weight percentage, an absorbent article was produced from this absorber and the amount of reversion and the diffusion length were measured.
The results of these measurements are shown in Table 1.

Example 2 As Example 1 except that an absorbent body was prepared by using 15 g of the water absorbent resin and 10 g of crushed pulp in Example 1 and having a weight of 25 g and a ratio of the water absorbent resin of 60% by weight. An absorbent article was prepared in the same manner, and the amount of reversion and the diffusion length were measured. The results are shown in Table 2.

Example 3 With respect to the water absorbent resin (B) obtained in Production Example 2, the pressurized water absorption amount after 30 seconds, the pressurized water absorption amount after 30 minutes, the saturated water absorption amount, and The weight average particle diameter was measured. On the other hand, using 8 g of the water-absorbent resin and 18 g of crushed pulp obtained in Production Example 2, the weight was 26 g and the ratio of the water-absorbent resin was 30 g by the method described above.
After producing an absorber having a weight percentage, an absorbent article was produced from this absorber and the amount of reversion and the diffusion length were measured.
The results of these measurements are shown in Table 1.

Example 4 Example 3 was the same as Example 3 except that 15 g of the water absorbent resin and 10 g of crushed pulp were used to prepare an absorber having a weight of 25 g and a water absorbent resin ratio of 60% by weight. An absorbent article was prepared in the same manner, and the amount of reversion and the diffusion length were measured. The results are shown in Table 2.

Example 5 With respect to the water absorbent resin (C) obtained in Production Example 3, the pressurized water absorption amount after 30 seconds, the pressurized water absorption amount after 30 minutes, the saturated water absorption amount, and The weight average particle diameter was measured. On the other hand, using 8 g of the water absorbent resin and 18 g of crushed pulp obtained in Production Example 3, the weight was 26 g and the ratio of the water absorbent resin was 30 g by the above-mentioned method.
After producing an absorber having a weight percentage, an absorbent article was produced from this absorber and the amount of reversion and the diffusion length were measured.
The results of these measurements are shown in Table 1.

Example 6 As Example 5 except that an absorbent body was prepared by using 15 g of the water absorbent resin and 10 g of crushed pulp in Example 5 and having a weight of 25 g and a ratio of the water absorbent resin of 60% by weight. An absorbent article was prepared in the same manner, and the amount of reversion and the diffusion length were measured. The results are shown in Table 2.

Example 7 With respect to the water absorbent resin (D) obtained in Production Example 4, the pressurized water absorption amount after 30 seconds, the pressurized water absorption amount after 30 minutes, the saturated water absorption amount, and The weight average particle diameter was measured. On the other hand, using 8 g of the water-absorbent resin obtained in Production Example 4 and 18 g of crushed pulp, the weight was 26 g and the ratio of the water-absorbent resin was 30 g by the method described above.
After producing an absorber having a weight percentage, an absorbent article was produced from this absorber and the amount of reversion and the diffusion length were measured.
The results of these measurements are shown in Table 1.

Example 8 Example 7 was the same as Example 7 except that 15 g of the water absorbent resin and 10 g of crushed pulp were used to prepare an absorber having a weight of 25 g and a water absorbent resin ratio of 60% by weight. An absorbent article was prepared in the same manner, and the amount of reversion and the diffusion length were measured. The results are shown in Table 2.

Example 9 With respect to the water absorbent resin (E) obtained in Production Example 5, the pressurized water absorption amount after 30 seconds, the pressurized water absorption amount after 30 minutes, the saturated water absorption amount, and The weight average particle diameter was measured. On the other hand, using 8 g of the water-absorbent resin and 18 g of crushed pulp obtained in Production Example 5, the weight was 26 g and the ratio of the water-absorbent resin was 30 g by the method described above.
After producing an absorber having a weight percentage, an absorbent article was produced from this absorber and the amount of reversion and the diffusion length were measured.
The results of these measurements are shown in Table 1.

Example 10 Example 9 was repeated except that an absorbent body having a weight of 25 g and a ratio of the water absorbent resin of 60% by weight was prepared by using 15 g of the water absorbent resin and 10 g of crushed pulp in Example 9. An absorbent article was prepared in the same manner, and the amount of reversion and the diffusion length were measured. The results are shown in Table 2.

Example 11 With respect to the water absorbent resin (C) obtained in Production Example 6, the amount of pressurized water absorption after 30 seconds, the amount of pressurized water absorption after 30 minutes, the saturated water absorption amount, and The weight average particle diameter was measured. On the other hand, using 8 g of the water absorbent resin and 18 g of crushed pulp obtained in Production Example 6, the weight was 26 g and the ratio of the water absorbent resin was 3 g by the above-mentioned method.
After producing an absorber of 0% by weight, an absorbent article was produced from this absorber and the amount of reversion and the diffusion length were measured. The results of these measurements are shown in Table 1.

Example 12 In Example 11, 15 g of the water absorbent resin and 10 g of crushed pulp were used, and the weight was 25 g.
An absorbent article was produced in the same manner as in Example 11 except that an absorber having a water absorbent resin content of 60% by weight was produced, and the amount of reversion and the diffusion length were measured. The results are shown in Table 2.

Example 13 With respect to the water absorbent resin (G) obtained in Production Example 7, the pressurized water absorption amount after 30 seconds, the pressurized water absorption amount after 30 minutes, the saturated water absorption amount, and The weight average particle diameter was measured. On the other hand, using 8 g of the water-absorbent resin and 18 g of crushed pulp obtained in Production Example 7, the weight was 26 g and the ratio of the water-absorbent resin was 3 by the method described above.
After producing an absorber of 0% by weight, an absorbent article was produced from this absorber and the amount of reversion and the diffusion length were measured. The results of these measurements are shown in Table 1.

Example 14 In Example 13, 15 g of the water absorbent resin and 10 g of crushed pulp were used, and the weight was 25 g.
An absorbent article was produced in the same manner as in Example 13 except that an absorber having a water absorbent resin content of 60% by weight was produced, and the amount of reversion and the diffusion length were measured. The results are shown in Table 2.

Example 15 With respect to the water absorbent resin (H) obtained in Production Example 8, the amount of pressurized water absorption after 30 seconds, the amount of pressurized water absorption after 30 minutes, the saturated water absorption amount, and The weight average particle diameter was measured. On the other hand, using 8 g of the water-absorbent resin obtained in Production Example 8 and 18 g of crushed pulp, the weight was 26 g and the ratio of the water-absorbent resin was 3 by the method described above.
After producing an absorber of 0% by weight, an absorbent article was produced from this absorber and the amount of reversion and the diffusion length were measured. The results of these measurements are shown in Table 1.

Example 16 In Example 15, 15 g of water absorbent resin and 10 g of ground pulp were used to weigh 25 g,
An absorbent article was produced in the same manner as in Example 15 except that an absorbent body containing 60% by weight of the water absorbent resin was produced, and the amount of reversion and the diffusion length were measured. The results are shown in Table 2.

[Comparative Example 1] With respect to the water absorbent resin (I) obtained in Production Example 9, the pressurized water absorption amount after 30 seconds, the pressurized water absorption amount after 30 minutes, the saturated water absorption amount, and The weight average particle diameter was measured. On the other hand, by using 8 g of the water-absorbent resin and 18 g of crushed pulp obtained in Production Example 9, the weight was 26 g and the ratio of the water-absorbent resin was 30 g by the method described above.
After producing an absorber having a weight percentage, an absorbent article was produced from this absorber and the amount of reversion and the diffusion length were measured.
The results of these measurements are shown in Table 1.

[Comparative Example 2] Comparative Example 1 except that in Comparative Example 1 15 g of water-absorbent resin and 10 g of crushed pulp were used to prepare an absorber having a weight of 25 g and a water-absorbent resin content of 60% by weight. An absorbent article was prepared in the same manner, and the amount of reversion and the diffusion length were measured. The results are shown in Table 2.

Comparative Example 3 With respect to the water absorbent resin (J) obtained in Production Example 10, the amount of pressurized water absorption after 30 seconds, the amount of pressurized water absorption after 30 minutes, the saturated water absorption amount, and The weight average particle diameter was measured. On the other hand, by using 8 g of the water-absorbent resin and 18 g of crushed pulp obtained in Production Example 10 and after producing an absorber having a weight of 26 g and a water-absorbent resin ratio of 30% by weight by the above-mentioned method, An absorbent article was prepared from the absorber and the amount of reversion and the diffusion length were measured. The results of these measurements are shown in Table 1.

[Comparative Example 4] Comparative Example 3 except that in Comparative Example 3 15 g of water-absorbent resin and 10 g of crushed pulp were used to prepare an absorber having a weight of 25 g and a water-absorbent resin content of 60% by weight. An absorbent article was prepared in the same manner, and the amount of reversion and the diffusion length were measured. The results are shown in Table 2.

[0113]

[Table 1]

[0114]

[Table 2]

As is clear from Tables 1 and 2, the absorbent article using the water-absorbent resin has a small amount of pressurized water absorption 30 seconds after the start of water absorption and a large amount of pressurized water absorption 30 minutes after the start of water absorption. Indicates that the amount of reversion is small and the diffusion length is large. Such a tendency appears in both cases where the concentration of the water absorbent resin in the absorber is 30% by weight and 60% by weight. As described above, the absorbent article using the water-absorbent resins (A) to (H) having a small initial water absorption amount and a large final water absorption amount exhibits excellent diffusivity even if the ratio of the resin in the absorber is large. In addition, it was confirmed that the amount of reversion also decreased.

[0116]

As described above, the absorbent article of the present invention is
Even if the ratio of the water absorbent resin in the absorber is large, not only the excellent diffusivity is exhibited, but also the amount of reversion is small. Therefore, the absorbent article of the present invention can exhibit excellent performance (water absorption property) capable of preventing leakage and giving a dry feeling in an actual use state.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an apparatus for measuring a pressurized water absorption amount.

[Explanation of symbols]

X measuring device 1 Balance 2 bottles 3 Air suction pipe 4 conduits 5 glass filters 6 measuring section 60 cylinders (of measuring part) 61 Nylon mesh (of measurement part) 62 Weight (of measurement part) 7 computer 8 artificial urine 9 Water absorbent resin

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08J 3/24 A61F 13/18 303 5/04 CEP 305 // C08L 101: 00 330 (72) Inventor Fujikake Masato 1-Irifune-cho, Shirima-ku, Himeji-shi, Hyogo Sumitomo Seika Chemical Co., Ltd. Functional Resin Research Laboratory F-term (reference) 3B029 BA17 4C003 AA09 AA12 DA04 4C098 AA09 CC03 DD05 DD06 DD10 DD13 DD14 DD23 DD24 DD25 DD26 DD27 DD28 DD29 DD30 4F070 AA03 AA29 AB03 AB08 AB13 AC87 AC89 AE08 GA06 GC01 4F072 AA02 AB03 AD01 AD09 AD52 AD53 AG04 AL01

Claims (8)

[Claims] 1. The pressurized water absorption amount of the artificial urine after 30 seconds from the start of water absorption is 10 g / g or less,
An absorbent body containing a hydrophilic fiber and a water-absorbent resin in which the pressurized water absorption amount of artificial urine after 20 minutes is 20 g / g or more. 2. The artificial urine has a pressurized water absorption of 5 g / g or less 30 seconds after the water absorption of the water-absorbent resin is started, and the artificial urine pressurized water absorption is 30 minutes after the water absorption is started.
The absorbent body according to claim 1, which is g / g or more. 3. The absorbent body according to claim 1, wherein the water absorption resin has a saturated water absorption amount of 40 g / g or more with respect to a physiological saline solution. 4. The weight average particle diameter of the water absorbent resin is 20.
Any one of claims 1 to 3, which is 0 to 600 μm.
Absorber according to item 1. 5. The water absorbent resin is subjected to a hydrophobic treatment,
The absorber according to any one of claims 1 to 4. 6. The water-absorbent resin is surface-crosslinked,
The absorber according to claim 5. 7. The absorber according to claim 1, wherein the ratio of the water absorbent resin is in the range of 30% by weight or more and less than 100% by weight of the total weight of the absorber. 8. An absorbent article, characterized in that the absorbent body according to any one of claims 1 to 7 is held between a liquid permeable sheet and a liquid impermeable sheet.