JP2675729C - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION       [0001]     [Industrial applications]   The present invention relates to a method for producing a water absorbent resin. More specifically, under pressure
Even when no pressure is applied, it shows a high absorption, especially when used for sanitary materials
And a method for producing the same.       [0002]     [Prior art]   In recent years, with the aim of absorbing body fluids, paper diapers and sanitary napkins
Water-absorbing resins are widely used as one of the constituent materials of raw materials.       [0003]   Examples of these water-absorbing resins include cross-linked polyacrylic acid partially neutralized products (particularly,
JP-A-55-84304, JP-A-55-108407, JP-A-55-1334
No. 13), a hydrolyzate of a starch-acrylonitrile graft polymer (Japanese Unexamined Patent Publication No.
No. 43995), neutralized starch-acrylic acid graft polymer (JP-A-51-12).
No. 5468), a saponified vinyl acetate-acrylate copolymer (Japanese Patent Laid-Open No.
No. 2-14689), acrylonitrile copolymer or acrylamide copolymer
Hydrolyzate (JP-A-53-15959) or cross-linked form thereof, cation
Crosslinked product of a reactive monomer (JP-A-58-154709, JP-A-58-154710)
No.) are known.       [0004]   Desirable properties of the water-absorbent resin include high absorption capacity and excellent contact with aqueous liquid
Water absorption rate, liquid permeability, gel strength of swollen gel, water absorption from base material containing aqueous liquid Raising suction force and the like can be mentioned. However, the relationship between these properties is not always correct.
Does not show a correlation, for example, the higher the absorption capacity, the higher the liquid permeability, gel strength, water absorption
Physical properties such as speed are reduced.       [0005]   As a method of improving the water absorption properties of such a water absorbent resin in a well-balanced manner,
A technique for cross-linking the resin near its surface is known, and various methods have been proposed so far.
Have been.       [0006]   For example, a method using a polyhydric alcohol as a cross-linking agent (JP-A-58-18023)
No. 3, JP-A-61-16903), polyvalent glycidyl compounds, polyaziridination
Compound, polyamine compound, polyisocyanate compound
-189103), a method using glyoxal (JP-A-52-117393)
), A method using a polyvalent metal (JP-A-51-136588, JP-A-61-257)
No. 235, JP-A-62-7745), a method using a silane coupling agent (particularly,
JP-A-61-211305, JP-A-61-252212, JP-A-61-264
No. 006), a method using an epoxy compound and a hydroxy compound (JP-A No. 2-13)
No. 2103), a method using an alkylene carbonate (DE-4020780)
Etc. are known. In addition, a method in which an inert inorganic powder is present during the crosslinking reaction (see
60-163956, JP-A-60-255814), divalent alcohol is present
(JP-A-1-292004), a method in which water and an ether compound are present
The method (Japanese Patent Laid-Open No. 2-153903) is also known.       [0007]   By these methods, the balance of various properties of the water-absorbent resin is somewhat improved.
However, it is still not enough, and higher quality is required. Especially near
For years, the absorption capacity under no pressure, which is one of the basic physical properties of conventional water-absorbent resin, has been maintained at a high level.
As it is, a resin with excellent absorption characteristics under pressure, especially absorption capacity under pressure is required
It has become. Of course, the absorption capacity under no pressure and the absorption capacity under pressure are also generally
This is a conflicting relationship, and this is the case with the water-absorbent resin surface cross-linking technology known so far.
At present, it was not possible to respond to these advanced needs.       [0008]     [Problems to be solved by the invention]   Accordingly, an object of the present invention is to provide a water absorbent resin and a method for producing the same.
Another object of the present invention is to exhibit a high absorption capacity under pressure as well as under no pressure,
A water-absorbent resin that exhibits particularly excellent performance when used as a raw material, and a method for producing the same are provided.
To provide.       [0009]     Means for Solving the Invention   The present inventors have further improved the water-absorbing properties of the water-absorbing resin to achieve the above object.
As a result of intensive studies, two or more types of cross-linking agents with different solubility parameters
Water absorption characteristics by crosslinking with a specific temperature range, especially under no pressure
While maintaining a high absorption capacity under high pressure, a resin with excellent absorption capacity under pressure
The present inventors have found that the present invention can be obtained, and have completed the present invention.       [0010]   That is, the present invention provides a water-absorbent resin as a base polymer having a carboxyl group.
The powder was treated with a solubility parameter (SP value) of 12.5 [(cal / cm^Three)^1/2]that's all
A first crosslinking agent capable of reacting with a carboxyl group in the solution, and a solubility parameter (SP value
) 12.5 [(cal / cm^Three)^1/2] Which can react with a carboxyl group in less than
Water-absorbent resin mixed with a crosslinking agent and heat-treated at a temperature of 160 ° C. or more
And the absorption capacity of physiological saline is 45 (g / g) or more,
Amorphous crushed water-absorbent resin having an absorption capacity of 30 (ml / g) or more (however,
One or more glycidyl phosphonates and polymers represented by general formula (1)
A mixture of one or more other reactive compounds capable of reacting with the functional groups in the
Excludes materials whose surface has been modified. ).     Embedded imageWherein R is alkyl, alkenyl or optionally unsubstituted Or aryl. )       [0011]   Hereinafter, the present invention will be described in more detail.       [0012]   The water absorbent resin used for the base polymer that can be used in the present invention is water.
A conventionally known resin that absorbs a large amount of water and forms a hydrogel in
It is necessary to have a boxyl group. Such resins include Polyac
Crosslinked product of partially neutralized lylic acid, hydrolysis of starch-acrylonitrile graft polymer
Pulverized product, partially neutralized starch-acrylic acid graft polymer, vinyl acetate-acrylic acid
Saponified acrylate copolymer, acrylonitrile copolymer or acrylic
Hydrolysates of amide copolymers or cross-linked products thereof, and carboxyl group-containing cross-linked polymers
Examples include modified vinyl alcohol and crosslinked isobutylene-maleic anhydride copolymer.
I can do it.       [0013]   The water absorbing resin used for such a base polymer is generally an unsaturated carboxylic acid, for example,
For example, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid,
Rotonic acid, itaconic acid, β-acryloxypropionic acid and their neutralized products
It is obtained by polymerizing a monomer component essentially containing at least one selected from the group consisting of:
Preferred monomer components are acrylic acid, methacrylic acid and their neutralized products.       [0014]   In the present invention, the water-absorbing resin used for the base polymer is, if necessary, another monomer.
May be used in combination with the above unsaturated carboxylic acid for polymerization. Specific examples of other monomers
As vinyl sulfonic acid, styrene sulfonic acid, 2- (meth) acrylamide
Do-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid
Acid, anionic unsaturated monomer such as 2- (meth) acryloylpropanesulfonic acid
And its salts: acrylamide, methacrylamide, N-ethyl (meth) a
Acrylamide, Nn-propyl (meth) acrylamide, N-isopropyl (
(Meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydro
Xyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate G, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol
Coal mono (meth) acrylate, vinylpyridine, N-vinylpyrrolidone, N
Nonionic parents such as acryloylpiperidine and N-acryloylpyrrolidine
Aqueous group-containing unsaturated monomer; N, N-dimethylaminoethyl (meth) acrylate
, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylamido
Propyl (meth) acrylate, N, N-dimethylaminopropyl (meth)
Examples include cationic unsaturated monomers such as acrylamide and their quaternary salts.
be able to.       [0015]   The amount of carboxyl groups in the water-absorbent resin used for the base polymer is
There is no limitation on the carboxy content per 100 g of the water-absorbent resin as the base polymer.
It is preferred that at least 0.01 equivalent of the hydroxyl group be present. For example, in the polyacrylic acid part
In the case of the crosslinked hydrate, the ratio of the unneutralized polyacrylic acid is 1 to 60 mol%.
And more preferably in the range of 10 to 50 mol%.
No.       [0016]   The water-absorbing resin used for the base polymer is also a self-crosslinking type that does not use a crosslinking agent.
Rather than internal crosslinks having two or more polymerizable unsaturated groups or two or more reactive groups
It is desirable that the agent is copolymerized or reacted in a very small amount. These internal crosslinking agents
Examples of the body include, for example, N, N'-methylenebis (meth) acrylamide,
I) Ethylene glycol di (meth) acrylate, (poly) propylene glycol
Rudi (meth) acrylate, trimethylolpropane tri (meth) acrylate
, Glycerin tri (meth) acrylate, glycerin acrylate methacrylate
EO modified trimethylolpropane tri (meth) acrylate, pentaerythris
Litol tetra (meth) acrylate, dipentaerythritol hexa (meth)
Acrylate, triallyl cyanurate, triallyl isocyanurate, tria
Ryl phosphate, triallylamine, poly (meth) allyloxyalkane,
Re) Ethylene glycol diglycidyl ether, glycerol diglycidyl ether
Ter, ethylene glycol, polyethylene glycol, propylene glycol, Glycerin, pentaerythritol, ethylenediamine, polyethyleneimine,
Glycidyl (meth) acrylate can be exemplified. Also inside these
Two or more crosslinking agents may be used. However, the water absorption properties of the resulting water absorbent resin
From the essential use of a compound having two or more polymerizable unsaturated groups as an internal crosslinking agent
It is preferable that the amount used is 0.005 to 2 with respect to the monomer component.
Mol%, more preferably 0.01 to 1 mol%.       [0017]   In order to obtain a water-absorbent resin used as a base polymer in the present invention, the above-mentioned monomer is polymerized.
In this case, bulk polymerization or precipitation polymerization can be performed, but performance and weight
Because of the ease of control, the polymerization of aqueous solution and reverse phase suspension
Preferably       [0018]   The shape of the water-absorbing resin used for the base polymer obtained by these polymerization methods is indeterminate
Various types such as crushed, spherical, fibrous, rod-like and substantially spherical are preferably used in the present invention.
It can be applied to sanitary materials such as liquid diffusibility, difficulty in moving and falling off pulp.
Considering that it is an amorphous crushed product obtained by aqueous solution polymerization and having an average particle size of 10
Those having a thickness of 0 to 1000 μm, especially 300 to 600 μm, are most preferable.       [0019]   The water-absorbent resin as a base polymer has a water content of 1 to 50%, preferably 1 to 50%.
-20%, more preferably 1-10%, which can be handled as a powder. powder
If not, both the first crosslinking agent and the second crosslinking agent used in the present invention are basebodies.
Not only does it penetrate into the water-absorbent resin used for the rimer and lower the water absorption capacity,
In some cases, the absorption characteristics underneath do not improve.       [0020]   The first crosslinking agent that can be used in the present invention has a solubility parameter (SP value) of 1
2.5 [(cal / cm^Three)^1/2The above can react with a carboxyl group
. The solubility parameter (SP value) is generally used as a factor indicating the polarity of a compound.
In the present invention, the polymer handbook, 3rd edition (WILEY INTER) is used.
Dissolution of solvent described in VII-527 to 539) Degree parameter δ [(cal / cm^Three)^1/2] Shall apply and this table
For the cross-linking agents not described, refer to VII-524 Small in the same handbook.
Substituting Hoy's cohesive energy constant described in VII-525 into the equation
Value δ [(cal / cm^Three)^1/2] Shall apply.       [0021]   Such a solubility parameter (SP value) 12.5 [(cal / cm^Three)^1/2]
As the first crosslinking agent capable of reacting with the carboxyl group as described above, ethylene glycol,
Propylene glycol, glycerin, pentaerythritol, sorbitol,
Tilene carbonate, propylene carbonate and the like are exemplified, and selected from these groups.
One or more of them can be used. Preferably a solubility parameter
-(SP value) 13.0 [(cal / cm^Three)^1/2].       [0022]   The second crosslinking agent that can be used in the present invention has a solubility parameter (SP value) of 1
2.5 (cal / cm^Three)^1/2Can react with carboxyl groups in less than
Physically, diethylene glycol, triethylene glycol, tetraethylene glycol
Recall, dipropylene glycol, tripropylene glycol, 1,3-buta
Diol, 1,4-butanediol, 1,5-pentanediole, 2,4-pe
Tandiol, 1,6-hexanediol, 2,5-hexanediol, tri
Methylolpropane, diethanolamine, triethanolamine, ethylene glycol
Recall diglycidyl ether, polyethylene glycol diglycidyl ether
, Glycerol polyglycidyl ether, diglycerol polyglycidyl ether
Polyglycidyl ether, polyglyceryl ether, propylene glycol diglyci
Zyl ether, polypropylene glycol diglycidyl ether, ethylene dia
Min, diethylenetriamine, triethylenetetramine, 2,4-tolylenediamine
Socyanate, hexamethylene diisocyanate, 4,5-dimethyl-1,3-
Examples include dioxolan-2-one, epichlorohydrin, epibromohydrin and the like.
One or more selected from these groups can be used. Preferably
Is the solubility parameter (SP value) 9.5 to 12.0 [(cal / cm^Three)^1/2]of
Is in the range.       [0023]   In the present invention, as the crosslinking agent, one or two selected from the group of the first crosslinking agents described above.
It is necessary to use one or more selected from the group consisting of at least one kind and the second crosslinking agent.
It is. Use only one kind of primary crosslinking agent or one kind of secondary crosslinking agent, or primary crosslinking
The combination of two or more cross-linking agents selected from the group consisting of
However, a water-absorbent resin having excellent absorption characteristics under pressure cannot be obtained.       [0024]   In selecting the first and second cross-linking agents, the solubility of the first cross-linking agent should be selected.
The difference between the solubility parameter (SP value) and the solubility parameter (SP value) of the second crosslinking agent is 2 [
(Cal / cm^Three)^1/2] Is preferably selected. Solubility parameter
Difference (SP value) is 2 [(cal / cm^Three)^1/2Less than two types of crosslinking
The effect of using a water-absorbing agent is difficult to appear.
There are things. More preferably, the solubility parameter of the first crosslinking agent (SP value)
The difference between the solubility parameter (SP value) of the second crosslinking agent and that of the second crosslinking agent is 3 [(cal / cm^Three)^1/2
] Is selected.       [0025]   The first crosslinking agent preferably has a molecular weight of 200 or less,
The crosslinking agent preferably has a molecular weight of 350 or less. Molecular weight of primary crosslinking agent
Is more than 200, the first crosslinking agent is used as a base polymer for the water-absorbing resin.
The water-absorbing resin obtained is easy to stay near the surface without penetrating from the surface to the inside.
Absorption characteristics under pressure may not be easily improved. In addition, the molecular weight of the second crosslinking agent is 350
In the case of exceeding the value, the water does not substantially penetrate into the water-absorbing resin as the base polymer and remains the same.
In some cases, the absorption characteristics of the resulting water-absorbent resin under pressure are hardly improved. Preferably
Are those having a molecular weight of 150 or less as the first crosslinking agent, and
Has a molecular weight of 150 to 300.       [0026]   The amount of the first and second crosslinking agents used in the present invention depends on the crosslinking agent used.
However, it is usually different from 100 parts by weight of the solid content of the water-absorbent resin as the base polymer.
On the other hand, 0.001 to 10 parts by weight of the first crosslinking agent and 0.001 to 10 parts by weight of the second crosslinking agent Range of parts. If the amount of the first and second crosslinking agents exceeds 10 parts by weight, it is uneconomical
In addition to achieving the optimum crosslinking effect that is the object of the present invention,
It tends to be excessive, and if the amount is less than 0.001 part by weight, water absorption under pressure
It is difficult to obtain the effect of improving various characteristics. Preferably 0.01 to 8 parts by weight of the first crosslinking agent,
The second crosslinking agent is in the range of 0.001 to 1 part by weight, more preferably 0.1 to 1 part by weight.
5 parts by weight, 0.005 to 0.5 parts by weight of the second crosslinking agent.       [0027]   In the present invention, the water-absorbing resin as the base polymer and the first and second crosslinking agents
When mixing is used, it is preferable to use water. In the present invention, the water used
The amount varies depending on the type, particle size and moisture content of the water-absorbent resin as the base polymer
Is 20 parts by weight per 100 parts by weight of the solid content of the powder of the water absorbent resin as the base polymer.
It is not more than 0.5 parts by weight, preferably 0.5 to 10 parts by weight.       [0028]   In the present invention, the first and second powders of the water-absorbent resin as the base polymer are used.
When mixing with a two-crosslinking agent, a hydrophilic organic solvent may be used. Hydrophilicity used
Organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol
, Iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol
Lower alcohols such as coal and t-butyl alcohol; ketones such as acetone;
Ethers such as dioxane and tetrahydrofuran; N, N-dimethylformamid
Amides such as dimethyl sulfoxide; and sulfoxides such as dimethyl sulfoxide.
You. In the present invention, the amount of the hydrophilic organic solvent used is
The optimum amount varies depending on the type and particle size of the water-absorbent resin, but usually the base polymer
20 parts by weight or less based on 100 parts by weight of the solid content of the water absorbent resin
Or 0.1 to 10 parts by weight.       [0029]   In the present invention, the first and second crosslinks with the powder of the water absorbent resin as the base polymer
In order to maximize the water absorption property under pressure obtained by the present invention,
If necessary, first and second crosslinking agents containing water and / or a hydrophilic organic solvent
The water-absorbent resin as a polymer is sprayed or dropped and mixed. Also use water for mixing In this case, a water-insoluble particulate powder may coexist.       [0030]   The preferred mixing device used for the mixing is large to ensure uniform mixing.
It is necessary to be able to create mixing power. A mixing device that can be used in the present invention
For example, cylindrical mixer, double-wall conical mixer, V-shaped mixer, ribbon-type mixer
Machine, screw type mixer, fluidized furnace rotary desk type mixer, air flow type mixer,
Double arm type kneader, internal mixer, pulverization type kneader, rotary mixer and screw
Mold extruder and the like.       [0031]   In the present invention, the water-absorbing resin as the base polymer is mixed with the first and second crosslinking agents.
After that, heating is further performed to crosslink the vicinity of the surface.       [0032]   When a heat treatment is performed after adding the crosslinking agent in the present invention, the heat treatment temperature is 160 ° C.
That is all. If the heat treatment temperature is lower than 160 ° C, the heat treatment takes a long time and productivity is high.
In addition to causing a decrease in the quality, uniform cross-linking is achieved with both the first and second cross-linking agents.
As a result, a resin having high water absorption properties under pressure, which is the object of the present invention, cannot be obtained. Better
Preferably, the heat treatment temperature is 170 to 230 ° C, more preferably 180 to 220 ° C.
Range.       [0033]   The heat treatment can be performed using a usual dryer or heating furnace, and the groove-type mixed drying
Dryer, rotary dryer, desk dryer, fluidized bed dryer, flash dryer, and red
An outside line dryer can be exemplified.       [0034]   Above water-absorbent resin obtained by the production method of the present invention, for example, under no pressure of physiological saline
Absorption capacity under pressure of 45 (g / g) and 30 (ml / g)
g) It shows unprecedented excellent physical properties as described above.       [0035]   Conventionally, if the absorption capacity under no pressure is increased, the absorption capacity under pressure is reduced,
Conversely, increasing the absorption capacity under pressure increases the absorption capacity under no pressure. However, the water-absorbent resin obtained in the present invention has no pressure and no pressure.
It shows excellent absorption characteristics in both rolling and reduction. Although the cause is not clear,
Mix water-absorbent resin as reminder with two or more types of cross-linking agents having different solubility parameters.
By cross-linking in a specific temperature range, the
The optimized distribution of the cross-linking agent and the rapid cross-linking reaction between
Crosslinks with a unique density gradient that were not achieved by the method in
It is presumed that it is formed near the surface. Also the base poly
The shape of the water-absorbent resin used as the mer is an irregularly crushed one as described above.
In addition to the above-mentioned excellent absorption properties, the liquid has good diffusion properties and can move and fall off the pulp.
Even less, not in the conventionally known water-absorbent resin, particularly suitable for sanitary materials and water-absorbent resin
Can be.       [0036]   Further deodorant, fragrance, inorganic powder, foaming agent, pigment to the water absorbent resin obtained in the present invention,
New functions by adding dyes, hydrophilic short fibers, fertilizers, oxidizing agents, reducing agents, water, salts, etc.
Can also be added.       [0037]     【The invention's effect】   According to the method of the present invention, absorption fold under no pressure, which is one of the basic physical properties of the water absorbent resin
Resin with excellent absorption characteristics under pressure, especially absorption capacity under pressure while maintaining high ratio
Can be easily manufactured.       [0038]   The water absorbing resin of the present invention has a high absorption capacity under no pressure, and an absorption capacity under pressure.
It also has excellent characteristics such as liquid diffusibility, difficulty in moving and falling from pulp, etc.
It is particularly suitable for use in sanitary materials such as disposable diapers and sanitary napkins.
It is.       [0039]     【Example】   Hereinafter, the present invention will be described in detail with reference to Examples, but the scope of the present invention is not limited to these Examples.
It is not limited to only.       [0040]   Various properties of the water absorbent resin were measured by the following methods.       [0041]   (A) Absorption capacity (no pressure applied)   0.2 g of water-absorbent resin is evenly distributed in a non-woven tea bag type bag (40 * 150 mm).
The solution was put in a container and immersed in a 0.9% by weight aqueous solution of sodium chloride (physiological saline). 3
0 minutes later, pull out the tea bag type bag, drain for a certain period of time,
Weight W₁Was measured. Perform the same operation without using a water-absorbent resin.
Mushroom weight W₀Was calculated, and the absorption capacity was calculated by the following (Equation 1).       [0042]     (Equation 1)       [0043]   (B) Absorption capacity under pressure   The absorption capacity under pressure is measured using the apparatus shown in FIG. The upper mouth of Bullet 1
2. Plug 3 into 2 and set the measuring table 4 and the air port 5 at the same height. Central part of measuring table 4
The filter paper 7 is placed on a glass filter 6 having a diameter of 70 mm. 55mm in diameter
The nonwoven fabric 8 is fixed to the lower end of the support cylinder 10 and the water-absorbent resin A 0.2 g is placed on the nonwoven fabric 8
And evenly spray 20g / cm^TwoA load 9 is applied. This non-woven fabric-water absorbing tree
Put the grease-load together with the supporting cylinder on the filter paper 7 on the glass filter 6, and in 30 minutes
Artificial urine (composition: urea 1.9%, NaCl 0.8%, CaCl_Two
0.1% and MgSO_Four0.1%) (Aml) and the following (Equation 2)
The absorption capacity under pressure (ml / g) was determined.       [0044]     (Equation 2)       Absorption capacity under pressure (ml / g) = A (ml) /0.2 (g) Formula (2)       [0045]   (C) Suction force   Pour 20 ml of artificial urine from the top of the tissue paper and remove the base material containing artificial urine.
It was made and 1 g of the water-absorbing resin was placed on the substrate. After 10 minutes, the swollen gel is collected.
The tissue was taken and weighed to determine the suction force (g / g) of the liquid from the tissue paper.
.       [0046]   (D) Absorption amount of the absorber under pressure   Take out the core from a commercial children's paper diaper (L size) and replace it with pulp 30
A core containing 7.5 g of the water-absorbing resin is inserted between g. This test diaper (
W₀g) 20g / cm^TwoPut on artificial urine with a load of 60 minutes and pull up after 60 minutes.
After draining, the weight of the diaper (W₁g) was measured. W₁More W₀Subtract the value of
Thus, the absorption amount (g) of the absorber under pressure was obtained.       [0047] [Reference example]   5500 g of an aqueous solution of sodium acrylate having a neutralization rate of 75 mol% (simple
Monomer concentration 33%) and N, N'-methylenebisacrylamide as a crosslinking agent.
After dissolving 58 g and degassing with nitrogen gas for 30 minutes, two sigma-type blades with an inner volume of 10 L
Feed into a reactor covered with a jacketed stainless steel double-arm kneader
The temperature of the monomer was maintained at 30 ° C., and the reaction system was further substituted with nitrogen.       [0048]   Next, 2.4 g of ammonium persulfate and 0.12 g of 1-ascorbic acid were added.
After 1 minute, polymerization started, and after 16 minutes, the peak temperature in the reaction system was 83 ° C.
, And the hydrogel polymer is subdivided into a diameter of about 5 mm.
60 minutes after the start, the hydrogel polymer was taken out.       [0049]   The obtained granulated hydrogel polymer was spread on a 50-mesh wire mesh,
It dried with hot air at 90 degreeC for 90 minutes. Pulverize the dried product using a vibration mill, and
Classify into a crushed, irregularly shaped base polymer having an average particle size of 400 μm. A water-absorbent resin powder (1) was obtained.       [0050] Embodiment 1   100 parts of powdery water-absorbent resin (1) as base polymer obtained in Reference Example 1
1 part of glycerin (SP value δ = 16.5) as a first crosslinking agent, and a second crosslinking agent
Ethylene glycol diglycidyl ether (SP value δ = 10.2) 0.0
5 parts, 3 parts of water and 1 part of ethyl alcohol were mixed with a cross-linking agent composition solution to obtain
The resulting mixture was heated at 195 ° C. for 40 minutes. Properties of the obtained water-absorbent resin (1)
Table 1 shows the performance evaluation results.       [0051] Embodiment 2   100 parts of powdery water-absorbent resin (1) as base polymer obtained in Reference Example 1
2 parts of ethylene carbonate (SP value δ = 14.7) as a first crosslinking agent,
Glycerol polydiglycidyl ether (SP value δ = 10.8
) A crosslinker composition solution consisting of 0.1 part, 4 parts of water and 1 part of isopropyl alcohol
After mixing, the resulting mixture was heated at 180 ° C. for 60 minutes. The resulting water-absorbing tree
Table 1 shows the performance evaluation results of the fat (2).       [0052] Embodiment 3   100 parts of powdery water-absorbent resin (1) as base polymer obtained in Reference Example 1
3 parts of propylene glycol (SP value δ = 12.6) as a first crosslinking agent,
Propylene glycol diglycidyl ether (SP value δ = 10
. 1) mixing a cross-linking agent composition solution consisting of 0.1 part, water 5 parts and methanol 2 parts,
The obtained mixture was heated at 195 ° C. for 40 minutes. The obtained water absorbent resin (3)
Table 1 shows the results of the performance evaluation.       [0053] Embodiment 4   100 parts of powdery water-absorbent resin (1) as base polymer obtained in Reference Example 1
2 parts of ethylene glycol (SP value δ = 14.6) as a first crosslinking agent, 0.1 part of diethylenetriamine (SP value δ = 10.7) as a crosslinking agent, 2 parts of water
And a cross-linking agent composition solution consisting of 1 part of isopropyl alcohol.
The mixture was heat-treated at 180 ° C. for 60 minutes. Performance evaluation of the obtained water absorbent resin (4)
The results are shown in Table 1.       [0054] [Comparative Example 1]   100 parts of powdery water-absorbent resin (1) as base polymer obtained in Reference Example 1
1 part of glycerin (SP value δ = 16.5), 3 parts of water and 1 part of ethyl alcohol
Parts of the crosslinking agent composition, and heat-treating the resulting mixture at 195 ° C. for 40 minutes.
I understood. Table 1 shows the performance evaluation results of the obtained comparative water absorbent resin (1).       [0055] [Comparative Example 2]   100 parts of powdery water-absorbent resin (1) as base polymer obtained in Reference Example 1
In addition, ethylene glycol diglycidyl ether (SP value δ = 10.2) 0.05
Parts, 3 parts of water and 1 part of ethyl alcohol by mixing a crosslinker composition solution.
The resulting mixture was heated at 195 ° C. for 40 minutes. The comparative water-absorbent resin obtained (2)
Table 1 shows the results of the performance evaluation.       [0056] [Comparative Example 3]   100 parts of powdery water-absorbent resin (1) as base polymer obtained in Reference Example 1
1 part of glycerin (SP value δ = 16.5) as a first crosslinking agent, and a second crosslinking agent
Ethylene glycol diglycidyl ether (SP value δ = 10.2) 0.0
5 parts, 3 parts of water and 1 part of ethyl alcohol were mixed with a cross-linking agent composition solution to obtain
The resulting mixture was heated at 140 ° C. for 40 minutes. The obtained comparative water absorbent resin (3
Table 1 shows the results of the performance evaluations.       [0057] [Comparative Example 4]   100 parts of powdery water-absorbent resin (1) as base polymer obtained in Reference Example 1
1 part of 1,3-butanediol (SP value δ = 11.6), ethylene glycol 0.05 parts of diglycidyl ether (SP value δ = 10.2), 3 parts of water and ethyl
A crosslinker composition solution consisting of 1 part of alcohol is mixed, and the resulting mixture is heated at 195 ° C. for 4 hours.
Heat treatment was performed for 0 minutes. Table 1 shows the performance evaluation results of the obtained comparative water absorbent resin (4).
Indicated.       [0058] [Comparative Example 5]   100 parts of powdery water-absorbent resin (1) as base polymer obtained in Reference Example 1
Glycerin (SP value δ = 16.5) 1 part, ethylene carbonate (SP value δ
= 14.7) A crosslinker composition solution consisting of 2 parts, 5 parts of water and 1 part of ethyl alcohol
After mixing, the resulting mixture was heated at 195 ° C. for 40 minutes. Obtained comparative suction
Table 1 shows the performance evaluation results of the aqueous resin (5).       [0059]     [Table 1]

[Brief description of the drawings]   FIG. 1 is a cross-sectional view of an absorption capacity measurement device under pressure used in the present invention. You.     (Explanation of symbols)     1 ... Bullet     2 ... Upper end of bullet     3 ... stopper     4 ... Measuring table     5 ... Air intake     6 ... Glass filter     7 Filter paper     8 ... non-woven fabric     9 ... Load   10 Support cylinder

Claims (1)

Claims: 1. A powder of a water-absorbing resin as a base polymer having a carboxyl group is carboxyl with a solubility parameter (SP value) of 12.5 [(cal / cm ³ ) ^1/2 ] or more. Mixed with a first crosslinking agent capable of reacting with a group and a second crosslinking agent capable of reacting with a carboxyl group with a solubility parameter (SP value) of less than 12.5 [(cal / cm ³ ) ^1/2 ], at least 160 ° C. A method for producing a water-absorbent resin, wherein the method comprises heat-treating at a temperature of 3 ° C. 2. A solubility parameter (SP value) of 13.0 [SP] as a first crosslinking agent.
(Cal / cm ³ ) ^1/2 ] or more. 3. A solubility parameter (SP value) of 9.5 to 1 as a second crosslinking agent.
2. The method according to claim 1, wherein a material in the range of 2.0 [(cal / cm ³ ) ^1/2 ] is used. 4. The method according to claim 1, wherein the difference between the solubility parameter (SP value) of the first crosslinking agent and the solubility parameter (SP value) of the second crosslinking agent is 2 [(cal / cm ³ ) ^1/2 ] or more. The method of claim 1, wherein a second crosslinking agent is selected. 5. The method according to claim 1, wherein the first crosslinking agent has a molecular weight of 200 or less and the second crosslinking agent has a molecular weight of 350 or less. 6. The method according to claim 1, wherein the first crosslinking agent is used in an amount of 0.1 to 5 parts by weight and the second crosslinking agent is used in an amount of 0.005 to 0.5 parts by weight based on 100 parts by weight of the water-absorbing resin as the base polymer. The described method. 7. An irregularly crushed water-absorbing resin having an absorption capacity of physiological saline of 45 (g / g) or more and an absorption capacity of artificial urine under pressure of 30 (ml / g) or more (however, Except those whose surface has been modified with a mixture of one or more glycidyl phosphonates of the formula (1) and one or more other reactive compounds capable of reacting with the functional groups in the polymer .). Embedded image Wherein R is optionally substituted alkyl, alkenyl or aryl.