JP3077294B2 - Water-absorbing resin composition and absorbent article using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-absorbent resin composition and an absorbent article using the same. More specifically, the present invention relates to a water-absorbent resin having an improved diffusion rate and an absorbent article using the same, which has excellent absorbability.

[0002]

2. Description of the Related Art In recent years, water-absorbent resins have been used not only in the field of sanitary materials such as sanitary products and disposable diapers, but also in water-stopping agents, dew condensation inhibitors,
Further, synthetic resins are being put to practical use for industrial uses such as a freshness preservative and a solvent dehydrating agent, greening, agricultural and horticultural uses, and the range of application is expected to be further expanded in the future. Examples of this type of water-absorbing resin include a hydrolyzate of a starch-acrylonitrile graft copolymer, a cross-linked carboxymethyl cellulose, a cross-linked polyacrylic acid (salt), an acrylic acid (salt) -vinyl alcohol copolymer, and polyethylene oxide. Crosslinked products and the like are known.

[0003] However, these water-absorbing resins have a low water-absorbing capacity or a low water-absorbing or diffusion rate even if the water-absorbing ability is high, or a so-called "mamako" when mixed with water. (Water swelling unevenness)
There was a drawback that water could not be absorbed efficiently and a long time was required for water absorption. Here, the water absorption speed is the water absorption speed of the resin itself, and is the speed at which the resin is absorbed so as not to "crank". The diffusion speed indicates the diffusivity of the liquid to the entire resin particles. This is a value measured by an apparatus as described later in the present invention, and is a so-called “mamako”, which is different from the water absorption rate.

Various improvements have been proposed for these disadvantages of the water-absorbent resin. However, as a promising method, the vicinity of the surface of the water-absorbent resin is reacted with a specific crosslinking agent or treated with a specific compound. Accordingly, a method of increasing the crosslink density near the surface or making the surface hydrophobic is known.

For example, a method of treating a water-absorbing resin with a polyvalent glycidyl compound is disclosed in JP-B-60-18690, JP-B-61-48521, and JP-B-62-16135.
JP, JP-A-60-147475, JP-A-60-147475
JP-A-163956, JP-A-2-1841 and the like, and a method of treating a water-absorbent resin with a polyhydric alcohol is disclosed in JP-B-63-19215 and the like. JP-A-1-1263 discloses a method of impregnating a water-absorbent resin with a monomer having a high viscosity and polymerizing the resin in the vicinity of the surface.
No. 14, etc. Also, Japanese Unexamined Patent Publication No.
No. 305 and JP-A-61-252212 disclose a method of treating a water-absorbing resin with a silane coupling agent.

[0006]

However, as far as the present inventors know, a water absorbing resin satisfying all of the absorption capacity, absorption rate, diffusion rate and the like has not been obtained by the conventional method.

An object of the present invention is to provide a water-absorbent resin composition having a significantly improved diffusion rate without reducing the water-absorbing ability of the water-absorbent resin.

[0008]

[Means for Solving the Problems]

[Summary of the Invention] <Summary> The present invention provides a water-absorbent resin composition in which the diffusion rate is greatly improved without lowering the water-absorbing ability of the water-absorbent resin.

The present inventors have made various studies to solve the above-mentioned problems of the water-absorbing resin. As a result, the carboxyl group and / or the carboxylate group treated with the silane coupling agent in the presence of water were obtained. The present inventors have found that a water-absorbent resin composition obtained from a water-absorbent resin containing silica and silica solves the above problems, and have completed the present invention.

That is, according to the present invention, a water-absorbent resin having a carboxyl group and / or a carboxylate group is prepared by adding a water-absorbent resin having a general formula of 0.001 to 10 parts by weight per 100 parts by weight of the resin in the presence of water.

XR _3-n SiY _n (wherein, X represents a group having a functional group capable of reacting with the functional group of the water-absorbing resin, R represents an organic group, Y represents a hydrolyzable group, And n is an integer of 1 to 3), and 100
The average particle size of 0.05 to 5 parts by weight per part by weight is 0.0
A water-absorbent resin composition comprising ultrafine particles of 5 μm or less and silica having a non-hydrophobic surface, and an absorbent article using the same.

[Specific description of the invention] <Water-absorbing resin> The water-absorbing resin used in the present invention has a general formula in the presence of water.

XR _3-n SiY _n (wherein, X represents a group having a functional group capable of reacting with the functional group of the water-absorbing resin, R represents an organic group, Y represents a hydrolyzable group, And n is an integer of 1 to 3).

In the present invention, the water-absorbing resin treated with the silane coupling agent must be a water-absorbing resin containing a carboxyl group or a carboxylate group.
Examples of such a water-absorbent resin include, for example, acrylic acid (salt) polymer, methacrylic acid (salt) polymer, acrylic acid (salt) / methacrylic acid (salt) copolymer, starch / acrylic acid (salt) graft copolymer. Polymer, saponified starch / acrylic acid ester graft copolymer, saponified starch / methacrylic acid ester graft copolymer, saponified acrylic acid / vinyl acetate copolymer, methacrylic acid ester / vinyl acetate copolymer Combined saponified product, starch / acrylonitrile graft copolymer saponified product, starch /
Saponified acrylamide graft copolymer, starch /
A crosslinked product of each polymer such as a saponified acrylonitrile / 2-acrylamide-2-methylpropanesulfonic acid graft copolymer, a saponified starch / acrylonitrile / vinylsulfonic acid graft copolymer, and further crosslinked with acrylic acid. Examples include crosslinked products of polyethylene oxide and sodium carboxymethylcellulose.

<Silane Coupling Agent> An important feature of the present invention is that the water-absorbing resin is treated with a silane coupling agent in the presence of water.

The silane coupling agent used in the present invention has the general formula

XR _3-n SiY _n (wherein, X represents a group having a functional group capable of reacting with the functional group of the water-absorbing resin, R represents an organic group, Y represents a hydrolyzable group, And n is an integer of 1 to 3). Here, the group X having a functional group capable of reacting with the functional group of the water-soluble resin includes an organic group having a glycidyl group, an amino group or a mercapto group, and the organic group R includes, for example, a methyl group and an ethyl group. And the like. Examples of the hydrolyzable group Y include an alkoxy group and an acetoxy group.

Examples of the silane coupling agent (I) include γ-glycidoxypropyltrimethoxysilane,
γ-glycidoxypropylmethyldiethoxysilane, β
-(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, γ
-Chloropropylmethyldimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride and the like.

The amount of the silane coupling agent used in the present invention varies somewhat depending on the type of water-absorbing resin, the amount of water to be present, and the like. %, Preferably 0.01 to 3% by weight. If the amount is too small, the effect of improving the water absorption rate and gel strength will not be obtained, and if it is too large, the water absorption capacity of the treated resin will decrease.

Further, in the present invention, if a treatment is carried out by adding dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, etc., which are generally known as a silanol condensation catalyst, together with the silane coupling agent, It is possible to effectively obtain a superabsorbent polymer having a controlled water absorption rate. The amount of the silanol condensation catalyst to be used is generally 0.1 to 500% by weight, preferably 1 to 100% by weight, based on the silane coupling agent.

<Water> The treatment of the water-absorbent resin with the silane coupling agent in the present invention is essentially performed in the presence of water. Even if the silane coupling agent treatment is performed in the absence of water, the intended purpose cannot be achieved. The water may be present in a form in which the superabsorbent polymer contains a predetermined amount of water in advance, or in a form in which water is additionally added.

The amount of water present in the present invention is 0.5 to 300% by weight, preferably 5 to 300% by weight, based on the superabsorbent polymer.
100% by weight. If the amount of water is too small, the superabsorbent polymer does not swell during the treatment, so that the reaction with the silane coupling agent does not effectively proceed, and the treatment takes a long time, and is disadvantageous in industrial practice. Becomes On the other hand, if the amount of water is too large, the gel strength of the obtained resin is improved, but the effect of improving the water absorption rate by the silane coupling agent is reduced, and a large amount of the silane coupling agent is required, and the water absorption capacity of the resin is increased. Also decrease.

<Treatment Method> The treatment with the silane coupling agent in the presence of water can be carried out in various modes. Examples of the treatment mode include, for example, a method in which a mixture of a water-absorbent resin, water, and a silane coupling agent is reacted under stirring, and a mixture of a water-absorbent resin, water, and a silane coupling agent in an inert solvent, in a slurry state. And a method in which a water-absorbent resin, water and a silane coupling agent are mixed in an inert solvent, and the inert solvent is removed, followed by a reaction.

The inert solvent used in each of these cases includes, for example, alcohols such as methanol and ethanol; ketones such as acetone and methyl ethyl ketone;
Ethers such as diethyl ether, dibutyl ether, dioxane, and tetrahydrofuran; n-pentane, n-
Hexane, n-heptane, cyclohexane, benzene,
Hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as carbon tetrachloride, methylene chloride, chloroform and ethylene dichloride. One of these inert solvents may be used, or two or more of them may be appropriately used in combination.

The amount of the inert solvent used varies depending on the type of the water-absorbing resin, the type of the inert solvent, and the like.
0 to 500% by weight. When the amount of the inert solvent used is small, the amount of substances handled in the treatment is reduced, and the volume efficiency of the treatment device and the like is improved, but the dispersibility of the water-absorbent resin during the treatment is deteriorated, and the water absorption performance is distributed. , An effective dispersion method is needed. On the other hand, if the amount of the inert solvent used is too large, the treatment reaction tends to proceed, but on the other hand, the amount of substances to be handled increases, the volumetric efficiency of the apparatus and the like deteriorates, and the treatment cost increases. Becomes

In the present invention, the treatment temperature with the silane coupling agent in the presence of water includes the type of the silane coupling agent, the amount of the silanol condensation catalyst, the type and amount of the inert solvent,
It differs depending on the amount of water and the type of water-absorbing resin, and cannot be specified unconditionally. However, it is usually appropriately selected from the range of 20 to 180 ° C, preferably 50 to 150 ° C. Although the treatment time with the silane coupling agent cannot be specified unconditionally, it is usually in the range of 0.5 to 6 hours. Completion of the treatment with the silane coupling agent performed as necessary is achieved by maintaining the treatment temperature at a high temperature of, for example, 100 ° C. or higher, or by removing water by evaporation. The resin treated with the silane coupling agent
As it is or after removing water, washing with an inert solvent is optionally performed.

<Ultrafine silica and composition> The ultrafine silica used in the present invention has an average particle diameter of 0.05.
μ, preferably 0.02 μ or less. If the average particle diameter exceeds 0.05 μ, the effect of improving the diffusion rate is difficult to be obtained, and in order to sufficiently exert the effects of the present invention, the amount of addition must be increased, which is economically disadvantageous.

The mixing ratio of the water-absorbent resin treated with the silane coupling agent and the ultrafine silica varies depending on the particle size and shape of the water-absorbent resin.
Usually, it is 0.05 to 5% by weight, preferably 0.1 to 2.5% by weight. If the mixing amount of the ultrafine silica particles is less than 0.05% by weight, a sufficient effect cannot be obtained. On the other hand, if it exceeds 5% by weight, the effect corresponding to the added amount cannot be obtained, and the water absorption may be impaired. Further, even in the case of ultrafine silica, if the surface is made hydrophobic, the effect of improving the diffusion rate cannot be obtained, and on the contrary, the diffusion rate may be impaired. Also, when other inorganic powders are used instead of silica, the effect of improving the diffusion rate cannot be obtained.

The composition according to the present invention can be obtained, for example, by preferably uniformly mixing and dispersing a predetermined amount of the above-mentioned specific ultrafine-particle silica in the above-mentioned water-absorbing resin. The mixing and dispersion can be performed by various conventionally known methods and means, but can be easily performed by using a mixer generally used for powder mixing. The addition of a third component such as a fragrance, a deodorant, a chelating agent, or a bactericide to the composition according to the present invention is not excluded unless the object and effects of the present invention are significantly impaired. .

The composition of the present invention thus obtained is
Since the diffusion rate is greatly improved without impairing the various water absorbing properties of the water-absorbing resin, it can be effectively used for various sanitary materials, particularly absorbent articles represented by disposable diapers and sanitary articles.

<Absorptive Article> As the absorbent article using the water-absorbent resin composition according to the present invention, it is used for all absorbent articles from simple ones as described later in the present invention to commercially available ones. can do. Taking a disposable diaper as an example, the structure is a disposable diaper having a liquid-permeable sheet on the front surface and a liquid-impermeable sheet on the back surface, and a water-absorbing layer containing a water-absorbing resin located between the two sheets. It is provided.

As the water-absorbing layer, a water-absorbing resin is uniformly sprayed between two sheet-like cotton-like pulp sheets, the cotton-like pulp is embossed, and a water-absorbing layer wrapped with tissue is used. Mix the flocculent pulp and the water-absorbent resin uniformly, wrap it with a tissue, place the flocculent pulp on it, and wrap it with a tissue. Spread the water-absorbent resin evenly between the pulp in two layers, emboss this cotton-like pulp, wrap the tissue with a water-absorbent layer, and put the water-absorbent resin between the sheet-like cotton-like pulp. Sprinkle evenly, place a tissue on it, place another piece of cotton pulp, emboss, and wrap the tissue with a water-absorbing layer.

[0030]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The artificial urine absorption capacity of the water-absorbent resin composition,
The diffusion rate was measured according to the following method. The evaluation of the absorbent article using the water-absorbent resin composition was carried out by measuring the absorption time, return amount, and diffusivity of the following diaper components by artificial urine.

<Artificial urine composition> Urea 1.94% Sodium chloride 0.80% Calcium chloride 0.06% Magnesium sulfate 0.11% Pure water 97.09%

<Artificial urine water absorption capacity>
Mesh nylon bag (20cm x 10cm size)
And immersed in 1 liter of artificial urine having the above composition for 30 minutes. (At the same time, soak a blank nylon bag)
After 30 minutes, the weight of the artificial urine absorbed by 1 g of the water-absorbent resin was determined as the liquid absorption amount by lifting the nylon bag, draining the water for 15 minutes, measuring the weight, and correcting the blank.

<Diffusion rate> The diffusion rate was measured using the apparatus shown in FIG. 1.0 g of the water-absorbent resin is placed on the nonwoven fabric on the support plate with small holes. The amount of water-absorbent resin absorbing artificial urine when it was brought into contact with artificial urine from the lower surface was measured. 2 after the start
The amount of artificial urine absorbed per minute was defined as the diffusion rate. Table 2 shows the artificial urine water absorption capacity and diffusion rate of each water absorbent resin composition.

<Evaluation of Absorbent Article> Cotton-like pulp processed into a sheet (basis weight 150 g / m ² , 350 c
(size of mx 120 cm) were prepared, 5 g of various water-absorbent resins or a water-absorbent resin composition were evenly dispersed in the meantime, and the cotton-like pulp was embossed to form a water-absorbent layer. This water-absorbing layer is divided into two tissues (basis weight 20 g /
m ² , 350 cm × 120 cm), a polyethylene sheet was placed below, a top sheet removed from a commercially available diaper was placed above, and the polyethylene sheet and the top sheet were heat-sealed to produce an absorber.

Thereafter, 50 ml of artificial urine was absorbed from the central part three times (total 150 ml) at 30 minute intervals, and 50 g / cm after 60 minutes (the time required for the third absorption was measured and taken as the absorption time). ^The artificial urine returned for 3 minutes at the pressure of ² was absorbed by the filter paper, and the absorbed artificial urine was used as the return amount.
After the measurement of the return amount, the diffusion distance of the artificial urine in the water-absorbent resin layer in the absorber was measured, and the result was defined as the diffusivity. Table 2 shows the evaluation of the three diaper constructs having an absorption time, a return amount, and a diffusivity.

<Production Example 1> 121 g of cyclohexane was put into a 500 ml four-necked round bottom flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas inlet tube, and 0.9 g of sorbitan monostearate was added. Then, nitrogen gas was blown in to dissolve dissolved oxygen.

Separately, in a 300 ml conical beaker, 70.0 g of a 25% aqueous solution of sodium hydroxide was added to a mixture of 45 g of acrylic acid and 6.4 g of water under ice-cooling to reduce 70% of the carboxyl groups. Neutralized. In this case, the monomer concentration in the aqueous solution corresponds to 45% by weight as the monomer concentration after neutralization. Then, N,
After adding 0.0048 g of N'-methylenebisacrylamide, 0.0109 g of sodium hypophosphite, and 0.0312 g of potassium persulfate as a polymerization initiator and dissolving them, nitrogen gas was blown out to expel dissolved oxygen.

The contents of the conical beaker having a capacity of 300 ml were added to the contents of the four-necked round bottom flask, dispersed by stirring, and the temperature of the flask was raised by an oil bath while bubbling nitrogen gas. 55 ℃
After reaching the vicinity, the internal temperature rose rapidly, and 75 minutes after
Reached. Next, the internal temperature is maintained at 65 to 70 ° C,
The mixture was reacted for 1 hour with stirring. In addition, stirring is 250
Performed at rpm.

When the stirring was stopped after the reaction for 1 hour, the wet polymer particles settled at the bottom of the round-bottomed flask, and thus could be easily separated from the cyclohexane phase by decantation. The obtained resin was transferred to a reduced-pressure drier, heated to 80 to 90 ° C. and dried to obtain a smooth water-absorbent resin A.

<Production Example 2> After taking out the resin obtained by polymerization in Production Example 1 for 1 hour, the oil bath was heated to 100 ° C., and azeotropic dehydration was carried out for 4 hours. . When the stirring was stopped, the resin particles settled at the bottom of the round bottom flask, so that the resin particles could be easily separated from the cyclohexane phase by decantation. As a result of analyzing the water content of the obtained wet resin, 2
It was 2% by weight.

Next, the rotor was put in, and the content was 200 ml.
60 g of this wet polymer (50 g of dry polymer), 60 g of cyclohexane, 0.025 g of γ-glycidoxypropyltrimethoxysilane as a silane coupling agent (0.05% by weight of polymer), and As a silanol condensation catalyst, 0.05 g of di-n-butyltin dilaurate (based on 200% by weight of a silane coupling agent) was added, mixed, treated at 60 ° C. for 30 minutes, heated to 105 ° C., and then treated for 1 hour. The resulting resin is transferred to a vacuum dryer, heated to 80 to 90 ° C. and dried,
A smooth water-absorbent resin B was obtained.

<Production Example 3> 50 g of methanol was added to 50 g of the resin obtained by polymerization in Production Example 1, and water 1 was stirred.
0 g and ethylene glycol diglycidyl ether 0.0
A mixed solution with 5 g was added, mixed, attached to an evaporator, heated to 105 ° C., and treated for 1 hour. The obtained resin was transferred to a reduced-pressure drier, heated to 80 to 90 ° C. and dried to obtain a smooth water-absorbent resin C.

<Production Example 4> 121 g of cyclohexane was placed in a 500-ml four-necked round-bottomed flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas inlet tube, and sorbitan monostearate (HLB4.7) 0 was added. After adding and dissolving 0.9 g, nitrogen gas was blown in to expel dissolved oxygen.

Separately, 46.7 g of a 25% aqueous solution of sodium hydroxide was added to a mixture of 30 g of acrylic acid and 44.7 g of water in a conical beaker having a capacity of 300 ml under ice-cooling to reduce 70% of the carboxyl groups. Neutralized. In this case, the monomer concentration in the aqueous solution corresponds to 45% by weight as the monomer concentration after neutralization. Next, 0.042 g of N, N'-methylenebisacrylamide as a cross-linking agent and 0.104 g of potassium persulfate as a polymerization initiator were added and dissolved, and nitrogen gas was blown out to expel dissolved oxygen.

The contents of the conical beaker having a capacity of 300 ml were added to the contents of the four-necked round bottom flask, dispersed by stirring, and the temperature of the flask was raised by an oil bath while bubbling nitrogen gas. 55 ℃
After reaching the vicinity, the internal temperature rises rapidly, and 73 minutes after a few minutes
Reached. Next, the internal temperature is maintained at 65 to 70 ° C,
The mixture was reacted for 1 hour with stirring. In addition, stirring is 250
Performed at rpm.

After the reaction for 1 hour, when the stirring was stopped, the wet polymer particles settled at the bottom of the round bottom flask, and could be easily separated from the cyclohexane phase by decantation. The obtained resin was transferred to a reduced-pressure drier, heated to 80 to 90 ° C. and dried to obtain a smooth water-absorbent resin D.

<Production Example 5> Without taking out the resin obtained by polymerization in Production Example 4, after polymerization for 1 hour, the oil bath was continuously heated to 100 ° C., and azeotropic dehydration was carried out for 4 hours. . When the stirring was stopped, the resin particles settled at the bottom of the round bottom flask, so that the resin particles could be easily separated from the cyclohexane phase by decantation. As a result of analyzing the water content of the obtained wet resin, 1
7% by weight. Next, the rotor 20
In a 0 ml eggplant-shaped flask, 60 g of this wet polymer
(50 g of dry polymer), 60 g of cyclohexane,
As a silane coupling agent, 0.025 g of γ-glycidoxypropyltrimethoxysilane (based on polymer 0.0
5% by weight), and di-n- as a silanol condensation catalyst.
0.05 g of butyltin dilaurate (based on 200% by weight of the silane coupling agent) was added and mixed.
After the minute treatment, the temperature was raised to 105 ° C., followed by treatment for 1 hour. The obtained resin was transferred to a reduced-pressure drier, heated to 80 to 90 ° C. and dried to obtain a smooth water-absorbent resin E.

<Production Example 6> To 50 g of the resin obtained by polymerization in Production Example 1, 50 g of methanol was added, and water was added under stirring.
0 g and ethylene glycol diglycidyl ether 0.0
A mixed solution with 5 g was added, mixed, attached to an evaporator, heated to 105 ° C., and treated for 1 hour. The obtained resin was transferred to a reduced-pressure drier, heated to 80 to 90 ° C. and dried to obtain a smooth water-absorbent resin F.

<Examples 1 to 10 and Comparative Examples 1 to 13> The water absorbing resins A to F (100
g) shows various types of ultrafine silica and other inorganic powders.
The mixture was added in the amount shown in 1 and mixed uniformly to prepare a water-absorbent resin composition. The types and amounts of the water-absorbent resin, ultrafine silica or other inorganic powder used are as shown in Table 1.

Table 2 shows the artificial urine water absorption capacity and diffusion rate of the water-absorbent resin composition or the water-absorbent resin of Table 1, and the absorption time of an absorbent article using the resin composition or the resin.
It shows the results of measuring the return amount and the diffusivity.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

The water-absorbent resin composition according to the present invention has a greatly improved diffusion rate without lowering the water-absorbing ability of the water-absorbent resin, and an absorbent article using the same. Shows excellent absorption.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an apparatus used for measuring a water absorption rate of a superabsorbent polymer.

[Description of Signs] 1 Superabsorbent polymer (1 g) 2 Support plate with small holes 3 Nonwoven fabric 4 Artificial urine 5 Buret 6 Rubber stopper 7 Valve 8 Valve 9 Air inlet

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Sueichi Kato 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Yuka Co., Ltd. In Yokkaichi Research Institute, Inc. (56) References JP-A-62-36410 (JP, A) 60-147475 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 1/00-101/16 C08K 3/00-13/08

Claims (4)

(57) [Claims] 1. A carboxyl group and / or a carboxyl group
A water-absorbing resin having a salt group in the presence of water,
00 parts by weight per the general formula ## EQU1 ## XR _3-n SiY n (wherein 0.001-10 parts by weight, X is a functional group capable of reacting with the functional groups of the water-absorbent resin
Represents a group having, R represents an organic group, Y and ones represents a hydrolyzable group, and n is treated with a silane coupling agent represented by a 1 to 3) integer, the one 100
The average particle size of 0.05 to 5 parts by weight per part by weight is 0.0
5 [mu] m following the form of ultrafine particles, water absorbent resin composition whose surface is composed of silica is hydrophobic. 2. A carboxyl group and / or a carboxyl group.
A water-absorbing resin having a salt group in the presence of water,
0.001 to 10 parts by weight of the general formula : XR _3-n SiY _n (wherein X represents a group having an epoxy group, and R represents a lower alcohol )
Y represents a hydrolyzable group, and n represents 1
A silane coupling agent represented by the following formula:
And 100 parts by weight of this
5-5 parts by weight of ultrafine particles having an average particle size of 0.05 μm or less
Water-absorbing tree composed of silica, non-hydrophobic surface
Fat composition. 3. A method in which a water-absorbent resin treated with a silane coupling agent is used in an amount of 0.01 to 100 parts by weight of the water-absorbent resin.
The water-absorbent resin composition according to claim 1 or 2, wherein the water-absorbent resin composition is treated with up to 3 parts by weight of a silane coupling agent. 4. An absorbent article comprising the water-absorbent resin composition according to claim 1 .