JP3466318B2 - Water-absorbing agent composition, method for producing the same, and absorbent article containing these water-absorbing agent compositions - 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 absorbing agent composition and a method for producing the same.

More specifically, the present invention not only excels in the absorption characteristics of body fluids such as urine, blood and secretory fluids and excels in gel stability, but also excels in hygroscopic fluidity, antistatic performance and rust prevention effect. The present invention also relates to a water-absorbing agent composition and a method for producing the same, and further, the present invention provides an excellent effect of improving various physical properties in surface cross-linking of a water-absorbent resin and a safety in which the residual amount of the surface cross-linking agent is greatly reduced. excellent water-absorbing composition and relates to their preparation, as well as the present invention relates to absorb article you containing these water-absorbent agent composition.

[0003]

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

Examples of water-absorbing polymers developed to date include, for example, crosslinked polyacrylic acid partially neutralized products (JP-A-55-84304, JP-A-55-108407, JP-A-55-133413). , A hydrolyzate of a starch-acrylonitrile graft polymer (JP-A-46-43995).
No.), a neutralized product of a starch-acrylic acid graft polymer (JP-A-51-125468), and a saponified product of a vinyl acetate-acrylic acid ester copolymer (JP-A-52-14689).
No.), a hydrolyzate of an acrylonitrile copolymer or an acrylamide copolymer (JP-A-53-15959).
Alternatively, these crosslinked products and carboxymethylcellulose crosslinked products (US Pat. Nos. 4,650,716 and 4,689,408).
No.), a crosslinked body of a cationic monomer (JP-A-58-15).
4709, JP-A-58-154710, US Pat.
906717, US Pat. No. 5,075,399, European Patent No. 0304143), crosslinked isobutylene-maleic anhydride copolymer (US Pat. No. 4,389,513), and copolymerized crosslinked body of 2-acrylamido-2-methylpropanesulfonic acid and acrylic acid (European). Japanese Patent No. 0068189) and the like are known.

Desirable properties of these water-absorbent polymers are high absorption capacity when contacted with an aqueous liquid, excellent absorption rate, liquid permeability, gel strength of swollen gel, and water from a substrate containing an aqueous liquid. Examples include the amount of suction to be sucked up. However, the relationship between these characteristics does not necessarily show a positive correlation, and for example, the higher the absorption capacity, the lower the physical properties such as liquid permeability, gel strength, and absorption rate.

Therefore, as a method of improving various water absorption characteristics of such a water absorbing polymer in a well-balanced manner, a technique of further cross-linking the vicinity of the surface of the water absorbing polymer is known, and various methods have been proposed so far. .

For example, a method using a polyhydric alcohol as a cross-linking agent (JP-A-58-180233 and JP-A-61).
No. 16903), polyhydric glycidyl compounds, polyhydric aziridine compounds, polyhydric amine compounds, polyhydric isocyanate compounds (JP-A-59-189103), and glyoxal (JP-A-52-117393).
No.), a method using a polyvalent metal (JP-A-51-13658).
No. 8, JP-A-61-257235, JP-A-62-77.
45), a method using a silane coupling agent (JP-A-61-211305, JP-A-61-252212,
JP-A-61-264006), a method using a monoepoxy compound (JP-A-60-98121), and a method using an epoxy group-containing polymer (US Pat. No. 4,758,617).
No.), a method using an epoxy compound and a hydroxy compound (JP-A-2-132103), a method using an alkylene carbonate (DE-4020780), and the like are known. Further, a method of allowing an inert inorganic powder to exist during the crosslinking reaction (Japanese Patent Laid-Open No. 163956/1985, Japanese Patent Laid-Open No. 60-2 / 1985)
No. 55814), a method in which a divalent alcohol is present (JP-A-1-292004), a method in which water and an ether compound are present (JP-A-2-153903), and an alkylene oxide addition of a monovalent alcohol. Of organic compounds, organic acid salts, lactams, etc. (European Patent No. 0555692)
No.), etc. are also known.

By these methods, although the balance of physical properties of the water-absorbent polymer and the absorption amount under pressure can be improved to some extent, the effect of improving the physical properties is still insufficient. Moreover, since the cross-linking agent used for the cross-linking treatment near the surface of the water-absorbent polymer easily remains on the resin surface, a safety problem newly occurs depending on the type of the cross-linking agent, such as when using an epoxy compound. There was an occasion. Therefore, a method of reducing the residual surface cross-linking agent (Japanese Patent Laid-Open No. 3-195705) has been proposed, but it requires an extremely complicated process and the effect of reducing the residual surface cross-linking agent is insufficient.

Another problem is that the resulting water-absorbent polymer itself tends to absorb moisture, which results in a decrease in hygroscopic fluidity under high temperature and high humidity, which is a work problem, and corrosion of the device due to rust. However, it was difficult to handle because it was easily charged. Further, as another problem, when the liquid to be absorbed is blood, the absorption amount of the water-absorbing polymer decreases because the blood component surrounds the individual water-absorbing polymer particles during absorption of the blood and prevents absorption. In particular, it has been the current situation that the use of the water-absorbing polymers known so far does not always give satisfactory results in applications such as sanitary napkins.

Therefore, a method of adding a specific compound such as salt or polyether to the water-absorbent polymer for the purpose of improving the absorbency of the water-absorbent polymer to blood (JP-A-58).
No. 501107, JP-A-55-50357, JP-A-54-70694, US Reissue Patent 33839, European Patent 0009977, US Pat. No. 4,190,563, etc.) have also been proposed. Indeed, although in this case the coagulation of the water-absorbent polymers is prevented to some extent,
In actuality, the expected effect cannot be obtained because the water absorption amount of the water-absorbent polymer itself is lowered or the suction amount for blood is insufficient.

As described above, the conventional water-absorbing polymer has a problem of safety in that the physical properties are not sufficiently improved by the surface cross-linking and the epoxy compound added near the surface remains. As another problem, the conventional water-absorbent polymer is not only insufficient in water-absorbing properties, particularly the blood-absorbing property, but also has a problem that fluidity is lowered after moisture absorption of particles, rust is generated due to surface water, and charging is caused. , Not always satisfactory.

[0012]

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art by a novel water-absorbing agent composition, a method for producing the same, and a water-absorbing structure containing the same. An absorbent article is provided. The water-absorbent composition of the present invention has excellent absorption properties and safety for blood and the like, and is therefore suitable for diapers, sanitary napkins, and jigs for incontinence and body fluids such as wound protection materials and wound healing materials. It is preferably applied to the absorbent article or biotechnology application.

[0013]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a water-absorbing agent composition containing a polyamino acid (salt) and a water-absorbing polymer can be applied to body fluids such as blood. Not only excellent in various absorption properties, but also extremely excellent properties in gel stability, rust prevention effect, fluidity after moisture absorption, antistatic effect, etc., and
The present inventors have found that the addition of polyamino acid (salt) at the time of surface cross-linking of the water-absorbent polymer has excellent physical properties and the residual surface cross-linking agent can be significantly reduced, and has completed the present invention.

That is, the present invention provides "(1) Water-soluble unsaturated monomer
-Absorbing polymer having a crosslinked structure obtained by polymerizing a polymer
A water absorbing agent composition containing: a water absorbing agent composition containing a polyamino acid (salt) and a water absorbing polymer. (2) Insoluble in water
Water absorption with cross-linked structure obtained by polymerizing saturated monomer
A water absorbing agent composition containing a polymer, the water absorbing polymer
In the vicinity of the surface of the water-absorbing agent, the water absorbing agent composition has an absorption amount of at least 25 g / g for 60 minutes under normal pressure in physiological saline (0.9 wt% sodium chloride aqueous solution) , and 10 in 20 ml of physiological saline. If the amount of suction per minute is small
Also 14 g / g , and a suction amount for 10 minutes with respect to 20 ml of bovine blood is at least 7 g / g. (3)
It has a crosslinked structure obtained by polymerizing water-soluble unsaturated monomers.
A method of producing a water-absorbing agent composition containing a water-absorbing polymer,
Preparation of water-absorbent agent composition admixing a carboxyl group-containing water-absorbent polymer over to <br/> polyamino acid (salt) aqueous solution having a crosslinked structure. (4) Obtained by polymerizing a water-soluble unsaturated monomer
Water-absorbing agent composition containing water-absorbing polymer having cross-linked structure
A method for producing a water-absorbing agent composition, which comprises polymerizing a water-soluble unsaturated monomer in the presence of a polyamino acid (salt) and a crosslinking agent. (5) 10 to 95 parts by weight of the water absorbent composition according to any one of claims 1 to 4 and 90 to hydrophilic fibers.
Absorbent comprising a water-absorbing structure containing 5 parts by weight
Goods. Is provided.

In the present invention, polyamino acid (salt)
Is a polyamino acid and / or a polyamino acid salt.

The present invention will be described in more detail below. The water-absorbent polymer useful in the present invention is a conventionally known resin which absorbs a large amount of water, preferably 10 to 100 times as much physiological saline as water, to form a substantially water-insoluble hydrogel. Such a compound is, for example, a partially neutralized crosslinked polyacrylic acid polymer (US Pat. Nos. 4,625,001, 4,654,039, 5,250,640, and 5,527).
5773, EP 456136, etc.), cross-linked and partially neutralized starch-acrylic acid graft polymer (US Pat. No. 4,076,663), cross-linked isobutylene-
Maleic acid copolymer (US Pat. No. 4,389,513),
Saponified vinyl acetate-acrylic acid copolymer (US Pat. No. 4,124,748), acrylamide (co) polymer hydrolyzate (US Pat. No. 3,959,569), acrylonitrile polymer hydrolyzate (US Pat. No. 3,93,509).
9), carboxymethyl cellulose crosslinked products (US Pat. No. 4,650,716) and the like.

Among these water-absorbing polymers, the preferable one is a polyacryl obtained by polymerizing a water-soluble unsaturated monomer containing acrylic acid (salt) as a main component in the presence of a crosslinking agent or a polysaccharide if necessary. It is an acid salt cross-linked polymer. As the polyacrylate cross-linked polymer, it is preferable that 50 to 90 mol% of the acid groups in the polymer are neutralized, and examples of the salt include alkali metal salts, ammonium salts, amine salts and the like. You can Further, a method for obtaining an acrylate suitable for polymerization of a water-absorbing polymer is disclosed in US Pat.
338810 and European Patent 0574260.

In the present invention, when a water-absorbing polymer is obtained by polymerizing a water-soluble unsaturated monomer containing acrylic acid and / or its salt as a main component, it may be used in combination with the above acrylic acid or its salt, if necessary. The hydrophobic unsaturated monomer may be copolymerized.

Specific examples of the other unsaturated monomer used include methacrylic acid, maleic acid, β-acryloyloxypropionic acid, vinylsulfonic acid, styrenesulfonic acid, 2- (meth) acrylamido-2-methyl. Anionic unsaturated monomers such as propanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid and salts thereof; acrylamide, methacrylamide, N-ethyl (meth) acrylamide, N -N-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N
-Dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, vinyl pyridine, N-vinyl pyrrolidone, N -Nonionic hydrophilic group-containing unsaturated monomers such as acryloyl piperidine and N-acryloyl pyrrolidine; N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethyl Cationic unsaturated monomers such as aminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide and quaternary salts thereof; hydrophobic non-ionic monomers such as isobutylene and stearyl (meth) acrylate. And the like can be mentioned sum monomer. The amount of the monomers other than acrylic acid used is usually 0 to 50 mol%, preferably 0 to 30 mol%, and more preferably 0 to 10 mol% in the total amount of the monomers.

The water-absorbing polymer used in the present invention has a cross-linking structure, and as a method of introducing it, a self-cross-linking type without a cross-linking agent or two or more polymerizable unsaturated groups / or 2 groups is used. Examples thereof include those that copolymerize or react with an internal cross-linking agent having one or more reactive groups / or a combination thereof. Of these, those obtained by copolymerizing or reacting with an internal crosslinking agent are preferable.

Specific examples of these internal crosslinking agents include, for example, N, N'-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate and tri. Methylolpropane tri (meth) acrylate, trimethylolpropane di (meth) acrylate,
Glycerin tri (meth) acrylate, glycerin acrylate methacrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, triary Lucyanurate, triallyl isocyanurate, triallyl phosphate, triallylamine, poly (meth) allyloxyalkane, (poly) ethylene glycol diglycidyl ether, glycerol diglycidyl ether,
Ethylene glycol, polyethylene glycol, propylene glycol, glycerin, pentaerythritol,
Examples thereof include ethylenediamine, polyethyleneimine, and glycidyl (meth) acrylate. These internal crosslinking agents may be used in combination of two or more kinds. Among these internal cross-linking agents, it is preferable to essentially use a compound having two or more polymerizable unsaturated groups from the water-absorbing property of the resulting water-absorbing polymer, and the amount of the monomer component is On the other hand, it is usually in the range of 0.005 to 3 mol%, more preferably 0.01 to 1.5 mol%, still more preferably 0.03 to 0.3 mol%.

During the polymerization, starch or cellulose is used.
Derivatives of starch, starch and cellulose, polyvinyl alcohol
Hydrophilic polymers such as cross-linked products of polyacrylic acid (salt) and polyacrylic acid (salt), chain transfer agents such as hypophosphorous acid (salt), foaming agents such as surfactants and carbonates, etc. May be added. Compounds added to these monomers are U.S. Pat. Nos. 4,076,663, 4,286082, and 432.
No. 0040, No. 4833222, No. 5118719
Nos. 5149750, 5154713, 52
64495 and European Patents 03729831 and 04.
No. 96594 is exemplified.

When the monomers are polymerized to obtain the water-absorbing polymer used in the present invention, bulk polymerization or precipitation polymerization can be carried out, but in view of performance and ease of polymerization control, simple polymerization is possible. It is preferable to carry out aqueous solution polymerization or reverse phase suspension polymerization using the monomer as an aqueous solution.

The concentration of the aqueous solution is 10 to 70% by weight,
It is preferably 20% by weight to a saturated concentration. The polymerization method is described in, for example, US Pat.
No. 376323, No. 4446261, No. 455293
No. 8, No. 462501, No. 4654393, No. 4
683274, 4690996, 472164
No. 7, No. 4769427, No. 4738867, No. 47
No. 48076, No. 4873299, No. 4985514
No. 5124416, No. 5247225, No. 52
No. 50640 is exemplified.

In these methods, the initiation of polymerization is
Potassium persulfate, ammonium persulfate, sodium persulfate, t-butyl hydroperoxide, hydrogen peroxide,
Although radical polymerization initiators such as 2,2′-azobis (2-amidinopropane) dihydrochloride and active energy rays such as ultraviolet rays and electron beams can be used, it is preferable to use radical polymerization initiators. When an oxidizing radical polymerization initiator is used, redox polymerization may be performed by using a reducing agent such as sodium sulfite, sodium hydrogen sulfite, ferrous sulfate and L-ascorbic acid (salt) together. The amount of these polymerization initiators and reducing agents used is based on all monomers,
Usually 0.001 to 2 mol%, preferably 0.01 to 0.
It is in the range of 5 mol%.

When the monomer is an aqueous solution, the gelled polymer after polymerization is preferably dried. The drying method used is hot air drying, drying with specific steam (US Pat. No. 490202), microwave drying (US Pat. No. 50).
75344), vacuum drying, drum dryer drying, azeotropic dehydration in a hydrophobic organic solvent, and the like, preferably 70 to 300 ° C., more preferably 100 to 25.
It is dried in the range of 0 ° C. Further, the gel polymer may be further neutralized prior to drying, and US Pat.
The gel polymer may be subdivided in advance by a method such as No. 73, or the supply to the dryer may be controlled by the method such as US Pat. No. 5,229,487.

The shape of the water-absorbent polymer obtained by the above polymerization is irregular crushed shape, spherical shape, fibrous shape, rod shape, substantially spherical shape,
Various things such as a flat shape can be preferably used in the present invention, and may be integrally fixed to a fibrous base material or a porous base material. Furthermore, these water-absorbent polymers may be porous, foamed, or granulated.

Among the shapes of these water-absorbent polymers, when the surface-crosslinking described later is carried out, from the viewpoints of absorption speed, wicking characteristics, improvement of absorption under pressure, reduction of residual surface-crosslinking agent, etc., it is preferably spherical or amorphous. Crushed water-absorbing polymer, particularly preferably amorphous crushed polymer obtained by aqueous solution polymerization and having an average particle size of 200 to 600 μm
It is preferable to use a water-absorbent polymer in which the weight of the resin having a particle size of less than 150 μm is 10% by weight or less. If the average particle size is less than 200 μm, it may be difficult to improve the absorption capacity under pressure. If it exceeds 600 μm, the absorption speed may be slow and it may take a long time to reach the saturated absorption amount. Further, when the resin having a particle diameter of less than 150 μm exceeds 10% by weight,
Note that it may be difficult to reduce the amount of the residual crosslinking agent. In addition, if an irregularly crushed shape is used as the shape, in addition to the above-mentioned excellent absorption characteristics, the safety is also high, and further, the diffusibility of the liquid is good, and the migration / dropping from the pulp is small, and the conventionally known water absorption The water absorbent composition may be particularly suitable for sanitary materials, which is not present in the water-soluble polymer.

Further, when the surface cross-linking described later is carried out, the water-absorbent polymer used in the present invention has a water content of 1 to 50%, preferably 1 to 20%, more preferably 1 to 10% and can be handled as a powder. Is. When the water content exceeds 50%, the surface cross-linking agent used in the present invention penetrates into the water-absorbing polymer. Therefore, even if polyamino acid (salt) is used, not only the absorption capacity is lowered but also the wicking property and pressure are increased. The absorption characteristics of may not be improved.

In the present invention, for example, a polyamino acid (salt) is essentially added to the water absorbing polymer obtained as described above to obtain a water absorbing agent composition.

The polyamino acid (salt) that can be used in the present invention is a dimer or more homopolymer or copolymer in which α-amino acids such as aspartic acid and lysine, β-amino acids and γ-amino acids are linked by peptide bonds. A polymer can be exemplified, and the D-form, L-form and DL-form are not particularly limited. Specifically, polyglycine, polyalanine, polyvaline, polyleucine, polyisoleucine, polyphenylalanine, polytyrosine, polyoxyproline, polyproline, polyserine, polythreonine, polytyrosine, polycysteine, polycystine, polymethionine, polytryptophan. , Polyaspartic acid, polyglutamic acid,
Examples thereof include polylysine, polyarginine, polyhistidine, salts thereof, and copolymers thereof. Among these, preferable polyamino acids (salts) include poly (diaminomonocarboxylic acid (salt)) such as polylysine and polylysine hydrochloride, polyaspartic acid, sodium polyaspartate, polyglutamic acid, sodium polyglutamate and the like. Polymers of these basic amino acids or acidic amino acids, such as aminodicarboxylic acids (salts), and salts thereof. As the molecular weight of the polyamino acid (salt) that can be used in the present invention, those having a low molecular weight called a dimeric polypeptide and having a molecular weight of several millions can be preferably used, and more preferable molecular weight is About 1 to 1,000,000, more preferably 100
It is about 0 to 500,000.

The water absorbing agent composition of the present invention essentially comprises the above water absorbing polymer and polyamino acid (salt),
The preferable ratio varies depending on the purpose of use, but the polyamino acid (salt) is 0.00 relative to 100 parts by weight of the water-absorbing polymer.
It is in the range of 5 to 30 parts by weight. If the amount of the polyamino acid (salt) is less than 0.005 parts by weight, the effect of the present invention is difficult to obtain, and if the amount is more than 30 parts by weight, the effect corresponding to the added amount is obtained. Not only
It is not preferable because the absorption characteristics may rather deteriorate.
Further, when a polyamino acid (salt) is essentially added to the surface cross-linking described later, the amount of the polyamino acid (salt) used varies depending on the cross-linking agent used for cross-linking in the vicinity of the surface, but the solid content of the water-absorbent polymer is 100% by weight. Usually 0.005 per part
-8 parts by weight, preferably 0.01-5 parts by weight, more preferably 0.1-3 parts by weight. When the amount is less than 0.005 parts by weight, it is difficult to obtain the effect of improving the wicking property or the absorption property under pressure and the effect of reducing the residual amount of the surface crosslinking agent.

In the present invention, a method of adding a polyamino acid (salt) to a water-absorbent polymer to obtain a water-absorbing agent composition is exemplified by a method of adding a polyamino acid (salt) in the step of obtaining a water-absorbent polymer. This can be adopted, and for example, the polyamino acid (salt) may be mixed in advance with the monomer aqueous solution before the polymerization, and the polyamino acid (salt) may be mixed in the reaction liquid during or after the polymerization. As another method, a method of post-adding to the water-absorbent polymer can also be adopted, but as a method of adding the polyamino acid (salt) to the water-absorbent polymer in a dry state, for example, both are mechanically mixed by a powder method. Dry blending or a method of adding and mixing one or both of them in the form of an aqueous dispersion or an aqueous solution may be used. Among these methods, the method of adding and mixing the polyamino acid (salt) in the form of an aqueous liquid to the water-absorbing polymer in a dry state is preferable from the viewpoint of the absorption characteristics of the resulting water-absorbing agent composition.

When the polyamino acid (salt) is added as an aqueous liquid, water alone or a mixture of water and a hydrophilic organic solvent can be used as the aqueous liquid, and the amount of the aqueous liquid is 100% of the solid content of the water-absorbing polymer. The amount is in the range of 0.1 to 50 parts by weight, preferably 1 to 30 parts by weight with respect to parts by weight. The hydrophilic organic solvent used is methyl alcohol,
Ethyl alcohol, n-propyl alcohol, iso-
Propyl alcohol, n-butyl alcohol, iso-
Lower alcohols such as butyl alcohol and t-butyl alcohol; ketones such as acetone; ethers such as dioxane, tetrahydrofuran and alkoxy (poly) ethylene glycol; amides such as N, N-dimethylformamide; sulfoxides such as dimethyl sulfoxide. Can be mentioned.

Further, in the present invention, when the polyamino acid (salt) is added to and mixed with the water-absorbent polymer in the form of an aqueous liquid, the water-absorbent agent composition after mixing is subjected to heat treatment, if necessary. Although the temperature of the heat treatment varies depending on the amount of the aqueous liquid added, the heating is usually performed in the range of 50 to 250 ° C. under the conditions such that the obtained water-absorbing agent composition of the present invention is obtained in a substantially dry state. It is preferably treated. Further, the heat treatment can be carried out using an ordinary dryer or a heating furnace, for example, a groove type mixing dryer, a rotary dryer, a desk dryer, a fluidized bed dryer, a gas stream type dryer, Examples thereof include an infrared dryer and the like.

Next, the surface cross-linking method of the present invention will be further described.

As described above, in the present invention, a method of obtaining a water absorbing agent composition by adding and mixing a polyamino acid (salt) in the form of an aqueous liquid to a water absorbing polymer in a dry state is preferable. Is a carboxyl group-containing water-absorbing polymer, it is preferable to add a cross-linking agent capable of reacting with a carboxyl group when the polyamino acid (salt) aqueous liquid is added and mixed to the water-absorbent polymer.
In the present invention, by using a polyamino acid (salt) for surface cross-linking, the absorption property under physiological saline and blood is particularly excellent, and the amount absorbed under pressure is particularly excellent, and the residual surface cross-linking agent is reduced and the safety is high. It is possible to obtain the water absorbent composition of That is, in the present invention, it was found that by adding the polyamino acid (salt) during the surface cross-linking of the water-absorbing polymer, various physical properties are excellent and the residual surface cross-linking agent is significantly reduced.

In the present invention, when a water-absorbing agent composition is obtained at the time of surface cross-linking by adding a cross-linking agent and a polyamino acid (salt), the water-absorbent polymer is mixed with the cross-linking agent or poly-amino acid (salt) by cyclohexane or pentane. The water-absorbing polymer may be dispersed in an organic solvent such as, but in order to maximize the features of the present invention, the following (1) to
The method (4) and the like can be preferably exemplified.

(1) A method in which a cross-linking agent containing water and / or a hydrophilic organic solvent and a polyamino acid (salt) are mixed in advance, if necessary, and then the mixture is sprayed or added dropwise to the water-absorbent polymer.

(2) A method in which a polyamino acid (salt) is mixed in advance with a water-absorbent polymer, and then a cross-linking agent containing water and / or a hydrophilic organic solvent is sprayed or added dropwise if necessary.

(3) A method in which a cross-linking agent containing water and / or a hydrophilic organic solvent, if necessary, is directly sprayed or added dropwise to the water-absorbent polymer, and then the polyamino acid (salt) is mixed.

(4) A method in which a cross-linking agent containing water and / or a hydrophilic organic solvent and a polyamino acid (salt) are sprayed or added dropwise to a water-absorbent polymer at the same time in parallel with two nozzles or the like, if necessary.

Further, in these methods, as described above, the cross-linking agent or the polyamino acid (salt) is mixed with the water-absorbent polymer as a solution using water or a hydrophilic organic solvent rather than dry blending. preferable. Further, among these methods (1) to (4), the method (1) in which the crosslinking agent and the polyamino acid (salt) are mixed in advance is preferable from the viewpoint of the water absorption property and the effect of reducing the residual amount of the crosslinking agent.

From the viewpoint of the effect of surface cross-linking, water-insoluble fine particle powder or a surfactant may be allowed to coexist when the polyamino acid (salt) or cross-linking agent is mixed.
Inorganic acids and organic acids exemplified in No. 295 may be further added. The inorganic acids exemplified in Japanese Patent Application No. 6-20295 are phosphoric acid, sulfuric acid, hydrochloric acid and the like, and the organic acids are organic acids such as citric acid, lactic acid and succinic acid, preferably saturated organic carboxylic acids. .

Crosslinking agent and polyamino acid (salt) in the present invention
When water is added to obtain a water absorbing agent composition at the time of surface crosslinking, it is preferable to use water. In the present invention, the amount of water used varies depending on the type and particle size of the water-absorbent polymer and the water content, but per 100 parts by weight of the solid content of the water-absorbent polymer,
It is in the range of 0.5 to 5 parts by weight, preferably 0.5 to 3 parts by weight. In addition, in the present invention, the hydrophilic organic solvent described above may be used when the water-absorbent polymer and the crosslinking agent / polyamino acid (salt) are mixed. The optimal amount of the hydrophilic organic solvent used varies depending on the type and particle size of the water-absorbing polymer, but is usually 0 to 10 parts by weight, preferably 0.1 part by weight based on 100 parts by weight of the solid content of the water-absorbing polymer. It is in the range of 1 to 5 parts by weight.

Further, a suitable mixing device used for the above-mentioned mixing is required to be able to generate a large mixing force in order to ensure uniform mixing. Examples of the mixing device that can be used in the present invention include a cylindrical mixer, a double-walled cone mixer, a high-speed stirring mixer, a V-shaped mixer, a ribbon mixer, a screw-type mixer, Fluidized furnace rotary desk type mixers, airflow type mixers, twin-arm type kneaders, internal mixers, crushing type kneaders, rotary type mixers and screw type extruders. .

Crosslinking agent and polyamino acid (salt) in the present invention
When a water-absorbing agent composition is obtained by adding the above to the surface-crosslinking, it is preferable to perform heat treatment. In the present invention, after mixing the water-absorbent polymer with the crosslinking agent and the polyamino acid (salt),
Preferably, the cross-linking agent and the polyamino acid (salt) are mixed in advance by the mixing method of the above (1), and then the mixture is mixed with the water-absorbent polymer, and then further heat treatment is preferably performed depending on the type of the cross-linking agent. Crosslinks near the surface.

When heat treatment is performed, the treatment temperature is 80 to 3
00 ° C is preferred. When the heat treatment temperature is lower than 80 ° C., the heat treatment takes a long time to cause not only a decrease in productivity, but also uniform surface cross-linking is not achieved, and the wicking property and the water absorption property under pressure which are the objects of the present invention are high. A water absorbing agent composition may not be obtained in some cases, and the crosslinking agent is more likely to remain. The heat treatment temperature depends on the type of crosslinking agent used,
Preferably 100 to 230 ° C, more preferably 160 to
It is in the range of 220 ° C. For the heat treatment, the above-mentioned ordinary dryer or heating furnace is used.

In the present invention, the crosslinker capable of reacting with the carboxyl group which can be used together with the polyamino acid (salt) is usually a known ionic or covalent crosslinker used for the above purpose. It is illustrated. Examples of the cross-linking agent include ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, 1,3-propanediol, dipropylene glycol, 2,2,4-trimethyl-1, 3-pentadiol, polypropylene glycol, glycerin, polyglycerin, 2-butene-1,4
-Diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,2-cyclohexanol, trimethylolpropane, diethanolamine, triethanolamine, poly Polyhydric alcohol compounds such as oxypropylene, oxyethyleneoxypropylene block copolymer, pentaerythritol and sorbitol; ethylene glycol diglycidyl ether, polyethylene diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether , Propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycidyl, γ-
Epoxy compounds such as glycidoxypropyltrimethoxysilane; polyvalent amine compounds such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyamide polyamine polyethyleneimine, and those polyvalent amines and haloepoxy compounds A polycondensate of 2,4-tolylene diisocyanate, hexamethylene diisocyanate, etc .; a polyvalent oxazoline compound such as 1,2-ethylenebisoxazoline; γ-glycidoxypropyltrimethoxysilane, γ-aminopropyl Silane coupling agent such as trimethoxysilane;
1,3-dioxolan-2-one, 4-methyl-1,3
-Dioxolan-2-one, 4,5-dimethyl-1,3
-Dioxolan-2-one, 4,4-dimethyl-1,3
-Dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl-1,3-
Dioxolan-2-one, 1,3-dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,
6-dimethyl-1,3-dioxan-2-one, 1,3
-Alkylene carbonate compounds such as dioxopan-2-one; epichlorohydrin, epibromhydrin, α
-Haloepoxy compounds such as methylepichlorohydrin;
Zinc, calcium, magnesium, aluminum, iron,
Examples thereof include one or more selected from hydroxides such as zirconium and polyvalent metal compounds such as chlorides. And, among these crosslinking agents, polyhydric alcohols, epoxy compounds, alkylene carbonate compounds,
One or more selected from polyvalent amine compounds and their epihalohydrin condensates are preferred. Among the above crosslinking agents, the effect of reducing the residual crosslinking agent, which is one of the objects of the present invention, becomes greater when an epoxy compound is used as an essential component of the crosslinking agent. Is preferably applied. In addition, Japanese Patent Application No. 4-33
Even when two or more kinds of cross-linking agents having different solubility parameter ranges as shown in No. 6392 are used in combination, the preferable effect of the present invention can be obtained. This Japanese Patent Application No. 4-33639
The first cross-linking agent in No. 2 is one capable of reacting with a carboxyl group at a solubility parameter (SP value) of 12.5 [(cal / cm ³ ) ^1/2 ] or more. The solubility parameter (SP value) is generally used as a factor representing the polarity of a compound, and in the present invention, the solubility parameter δ [of the solvent described in Polymer Handbook Third Edition (published by WILEY INTERSCIENCE) VII-527-539]. (Cal / cm ³ ) ^1/2 ] shall be applied, and for cross-linking agents not listed in this table, Hoy's described in VII-525 in the Small's formula in VII-524 of the same handbook. The value δ [(cal / c
m ³ ) ^1/2 ] shall apply.

Such a solubility parameter (SP value) 1
Examples of the first cross-linking agent capable of reacting with a carboxyl group at 2.5 [(cal / cm ³ ) ^1/2 ] or more include ethylene glycol, propylene glycol, glycerin, polyglycerin, pentaerythritol, sorbitol, ethylene carbonate, propylene carbonate. And the like, and one or more selected from these groups can be used. Preferably, the solubility parameter (SP value)
13.0 to 18.0 [(cal / cm ³ ) ^1/2 ]. Further, among these first crosslinking agents, those having a molecular weight of 200 or less, more preferably 50 to 150, are preferably used.

The second cross-linking agent has a solubility parameter (SP value) of less than 12.5 [(cal / cm ³ ) ^1/2 ] and can react with a carboxyl group. Specifically, diethylene glycol, triethylene glycol,
Tetraethylene glycol, dipropylene glycol,
Tripropylene glycol, 1,3-butanediol,
1,4-butanediol, 1,5-pentanediol,
2,4-Pentanediol, 1,6-hexanediol, 2,5-hexanediol, trimethylolpropane, diethanolamine, triethanolamine, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, polyglycerol Polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, ethylenediamine, diethylenetriamine, triethylenetetramine, 2,4-tolylene diisocyanate, hexamethylene diisocyanate, 4,5-dimethyl-1,3-
Dioxan-2-one, epichlorohydrin, epibromohydrin, etc. can be illustrated, and 1 type (s) or 2 or more types selected from these groups can be used. Preferably, the solubility parameter (SP value) is 9.5 or more and 12.0.
It is in the range of less than [(cal / cm ³ ) ^1/2 ]. Further, among these second cross-linking agents, the molecular weight is preferably 350.
Below, those of 150 to 300 are more preferably used. In selecting the first cross-linking agent and the second cross-linking agent, the difference in solubility parameter (SP value) between the first cross-linking agent and the second cross-linking agent is 2 [(cal / cm ³ ) ^1/2 ] or more. Furthermore, it is preferable to select ³ or more [(cal / cm ³ ) ^1/2 ].

In the present invention, the amount of the cross-linking agent used together with the polyamino acid (salt) varies depending on the kind of the cross-linking agent used, but the solid content of the water-absorbent polymer of the present invention is 1
0.001 to 10 parts by weight, preferably 0.005 to 8 parts by weight, more preferably 0.01
It is in the range of from 5 to 5 parts by weight, most preferably from 0.01 to 2 parts by weight, and if the amount is within this range, the water absorption is excellent in wicking properties for physiological saline and blood and in absorption properties under pressure. An agent composition is obtained. When the amount used exceeds 10 parts by weight, not only is it uneconomical, but it tends to be an excessive amount for achieving a proper crosslinking effect, and the crosslinking agent tends to remain even if a polyamino acid (salt) is used. On the contrary, 0.0
When the amount is less than 01 parts by weight, it is difficult to obtain the effect of improving the wicking property and the absorption property under pressure. When the first crosslinking agent and the second crosslinking agent are used in combination by the method described in Japanese Patent Application No. 4-336392, the amount of the first crosslinking agent is 100 parts by weight of the solid content of the water absorbent resin. On the other hand, normally 0.
001 to 10 parts by weight, preferably 0.01 to 8 parts by weight,
The amount of the second crosslinking agent is usually 0.001 to 10 parts by weight, preferably 0.001 to 1 part by weight, more preferably 0.005 to 5 parts by weight.
It is in the range of 0.5 parts by weight.

Crosslinking agent and polyamino acid (salt) according to the present invention
When a water-absorbing agent composition is obtained at the time of surface cross-linking with the addition of polyamino acid, the distribution of the cross-linking agent can be optimized by the effect of polyamino acid (salt). It is possible to obtain a water-absorbing agent composition having a high absorption capacity, and it is possible to greatly reduce the residual amount of the crosslinking agent. Conventionally, when a highly reactive one such as an epoxy compound is used as the surface cross-linking agent, residual of several tens to 1000 ppm order has occurred, but in the present invention, the residual amount reduction is greatly reduced to the water absorption characteristics. An excellent water absorbing agent composition can be efficiently obtained in terms of process. Although the cause of this is not clear, mixing the polyamino acid (salt) and the cross-linking agent into the water-absorbent polymer and heat-treating it causes no adverse effect on the cross-linking agent itself, and thus, in the vicinity of the surface of the water-absorbent polymer. It is speculated that the distribution of the cross-linking agent is optimized and a uniform cross-linking reaction occurs rapidly, so the residual amount of cross-linking agent is significantly reduced and cross-links with a uniform density gradient are formed near the particle surface. To be done.

As described above, the water absorbing agent composition of the present invention obtained by adding a polyamino acid (salt) to a water absorbing polymer by various methods in the presence or absence of a crosslinking agent,
It excels not only in the absorption characteristics of body fluids such as urine, blood, and secretory fluids, but also in the gel stability, as well as hygroscopic fluidity, antistatic performance
It is possible to obtain a novel water-absorbing agent composition which is also excellent in rust prevention effect. Furthermore, when a water-absorbing agent composition is obtained at the time of surface cross-linking by adding a cross-linking agent and a polyamino acid (salt) in the present invention, the effect of improving the physical properties by surface cross-linking is excellent and the surface cross-linking agent such as an epoxy compound remains. A water-absorbing agent composition having a significantly reduced amount and excellent in safety can be obtained.

In addition to the water-absorbing agent composition containing the polyamino acid (salt) and the water-absorbing polymer obtained as described above, a new water-absorbing agent composition and water-absorbing agent using these water-absorbing agent compositions are also provided. The present invention also provides an elastic structure and an absorbent article. In the present invention, a water-absorbing agent composition having a remarkably excellent suction amount for physiological saline and bovine blood has been newly found.

Up to now, the amount of suction for artificial urine is 14 g
It has been proposed that a water-absorbing agent of 1 g / g or more can reduce the leakage of a paper diaper (JP-A-63-21902), a water-absorbing material having an excellent absorption capacity for blood (JP-A-6-25543, etc.) and the like. ing. However, these known techniques do not always satisfy the liquid suction force (suction amount) for highly viscous liquids such as blood and menstrual blood, and loose feces. A water-absorbing agent composition having the above problems has been found. In particular, when the sanitary napkin or diaper having a high blending ratio of the water absorbing composition, particularly when the content of the water absorbing composition in the water absorbing structure is 50% by weight or more, the water absorbing composition of the present invention is It was also found in the present invention that the balance of the normal pressure absorption amount with respect to physiological saline, the suction amount, and the suction amount with respect to bovine blood is important.

Therefore, according to the present invention, the absorption amount of the physiological saline at normal pressure is at least 25 g / g, the suction amount of the physiological saline is 14 g / g or more, and the suction amount of bovine blood is at least 7 g / g. The present invention also provides a water-absorbing agent composition, a water-absorbing structure containing the same, and an absorbent article.

In the water absorbing agent composition of the present invention, the amount of suction for physiological saline and the amount of suction for bovine blood carry the water absorbing agent composition when the absorbent article is a sanitary material such as a disposable diaper or a sanitary napkin. Quickly absorbs urine and blood diffused in the hydrophilic fiber material, stably maintains the diffusivity of the hydrophilic fiber material over time, and there is no discomfort to the skin.
This is an essential factor for obtaining an absorbent article with little return of urine or blood. Further, it has been found that especially when the suction amount for bovine blood is more than 7 g / g, the compounding ratio of the water absorbing agent composition in the water absorbing structure can be significantly increased (50% by weight or more). . Although the cause of this is not clear, in the case of a viscous liquid such as blood, it is presumed that the ratio of interparticle blocks caused by the high concentration of the water-absorbent composition in the water-absorbing structure is further increased, and the wicking characteristics for bovine blood. It is presumed that the difference between is more important.

Further, in the water-absorbent composition of the present invention, the absorption amount at normal pressure of physiological saline is preferably at least 3.
5 g / g, the suction amount for physiological saline is preferably 17
It is more than g / g, and the suction amount for bovine blood is preferably at least 10 g / g, which is an extremely high value which has never been obtained. In addition, in the present invention, when a water absorbing agent composition is obtained at the time of surface cross-linking by adding a crosslinking agent and a polyamino acid (salt), the water absorbing agent composition of the present invention has an absorption capacity under pressure of 30.
(Ml / g) or more, and even when the epoxy compound is used as the surface cross-linking agent, the residual amount is reduced to 2 ppm or less.

In the water-absorbent composition of the present invention, the amount of physiological saline absorbed at normal pressure is an important factor in that it affects the absorption capacity of the absorbent article, but this amount of absorption should be increased. In that case, there is a trade-off relationship between the amount of suction and the amount of suction, such that the amount of suction decreases and the performance of the absorbent article is adversely affected. Therefore, the present invention having excellent absorption characteristics which has never been obtained for the first time is obtained by using the water-absorbing agent composition of the present invention in which the absorption amount and the suction amount are controlled within specific ranges, respectively, with the hydrophilic fiber in a specific compounding ratio. Thus, it becomes possible to obtain the water absorbent structure and the absorbent article.

The water absorbent structure of the present invention comprises 10 to 95 parts by weight of the water absorbent composition of the present invention and 90 to 5 parts by weight of hydrophilic fibers.
It is preferably composed of 50 to 95 parts by weight of the water absorbent composition and 50 to 5 parts by weight of hydrophilic fibers, and these forms a matrix in a state of being mixed with each other or dispersed in a fiber sheet.

Hydrophilic fibers useful in the water absorbent structure of the present invention include, for example, ground wood pulp air-laid.
The shape of the bat is preferable, and the structure thereof is, for example, US Pat.
It is well known in the field of manufacturing diapers as disclosed in JP-A-610678. In the present invention, in addition to the crushed pulp as hydrophilic fibers, cotton linters, European Patent Nos. 0429112 and 0427 are also used.
Examples thereof include crosslinked cellulose fibers described in No. 316, rayon, cotton, wool, acetate, vinylon and the like.

The formation of the water-absorbing structure of the present invention is possible in any number of ways, including the methods currently used in the manufacture of diapers that are commercially available, and any suitable method of forming the water-absorbing structure can be used. Examples are, for example, US Pat. Nos. 4,578,068, 4,666,975, 4,673,402, and 468.
No. 5915, No. 4765780, No. 504702.
No. 3 and No. 5156902.

The water-absorbent structure thus obtained is preferably compression molded to have a density of 0.06 to 0.5 g / cc. In the present invention, the thickness of the water-absorbing structure containing the water-absorbing agent composition in a relatively high concentration is relatively thin, and the absorbent capacity can be efficiently exhibited. Therefore, the density is not within this range. preferable. If the density exceeds this range, the water-absorbent structure becomes hard, and if it is lower than this range, the absorption efficiency of the water-absorbent structure decreases, which is not preferable. Thus, the water absorbent structure of the present invention may have an average thickness of less than 40 mm, preferably less than 10 mm, more preferably less than 5 mm.
Furthermore, the basis weight of the water absorbent structure in the present invention is 0.01
A range of ˜0.20 g / cm 2 is preferred.
When the grammage is smaller than this range, the strength of the water-absorbent structure is insufficient, which is not preferable, and when the grammage is larger than that range, the water-absorbent structure becomes hard and may not be preferable for application to absorbent articles.

Further, in the present invention, in the water-absorbing structure comprising the water-absorbing agent composition and the hydrophilic fiber, 100 weight of the hydrophilic fiber is used for the purpose of improving the shape retention of the water-absorbing structure when absorbing water. Up to 40 parts by weight of thermoplastic fibers per part can be included in the water-absorbing structure.
Examples of such thermoplastic fibers include polyethylene, polypropylene, polyester fibers, polyester, polyamide, copolymers of bicomponent fibers, and the like, and composite fibers of these.

The water-absorbent structure of the present invention thus obtained can be sandwiched and fixed between a liquid-permeable surface material and a liquid-impermeable back material to obtain the absorbent article of the present invention. it can. Further, the absorbent article of the present invention may include a large number of members known in the art, such as a diffusion layer, leg elastic members, waist elastic members, and tape. The absorbent article of the present invention includes a diaper, training pants, a sanitary napkin,
It can be applied to various products that need to absorb a large amount of liquid, such as surgical pads, wound protection materials, incontinence clothing, and pet sheets.

Further, with respect to the water absorbent composition or the water absorbent structure obtained in the present invention, a deodorant, a fragrance, an inorganic powder, a foaming agent, a pigment, a dye, a hydrophilic short fiber, a plasticizer, a binder, an interface. A new function may be added by adding a compound such as an activator, a fertilizer, an oxidizing agent, a reducing agent, water, or a salt. Also,
The water absorbing agent composition of the present invention may be further granulated or molded.

It should be noted that such a compound is described in US Pat.
No. 367, No. 4190563, No. 4500670,
No. 4693713, No. 4812486, No. 4863.
No. 989, No. 4929717, No. 4959060,
No. 4972019, No. 5078992, No. 5229
488 and European Patents 0009977 and 04930.
No. 11 and the like are exemplified. The granulation method is exemplified in US Pat. No. 4,734,478, European Patents 0450922, 480031 and the like.

[0069]

EXAMPLES Examples will be shown below, but the present invention is not limited to these examples. In the following examples, all parts and% are parts by weight and% by weight, unless otherwise specified.

The absorption amount of the water-absorbent agent composition against normal saline at normal pressure, the suction amount against physiological saline solution, and the suction amount against bovine blood were measured by the following methods. In addition, the fluidity after moisture absorption, the rust preventive effect, the gel stability, the antistatic performance, the amount of the residual crosslinking agent, and the absorption capacity under pressure in the present invention were also measured by the methods described below.

(1) A water absorbent composition having an absorption amount of about 0.2 g for physiological saline was uniformly put in a non-woven tea bag type bag (40 mm × 150 mm), and a large excess of physiological saline (0.9 wt. % Saline) to swell the composition for 60 minutes, and then the tea bag type bag containing the swollen gel is pulled up for 5 seconds and placed on 24 sheets of toilet paper (57 mm × 50 mm, 19 g / square meter). Draining was performed for 10 seconds, and the weight was measured. The weight of the water-absorbent composition is calculated by subtracting the blank weight W0 from the weight W1 of the tea bag bag containing the swelling gel as the blank W0 after the liquid absorption of only the tea bag bag, according to (Equation 1). The absorption amount (g / g) of the water absorbent composition was calculated by dividing by.

[0072]

[Equation 1]

(2) A 16-layered toilet paper (55 mm × 75 mm, 19 g / dip) in which 20 ml of physiological saline solution in a dish having an inner diameter of 95 mm was dipped with a water-absorbing agent composition having a suction amount of about 1 g for physiological saline solution. Swelling gel was sampled and weighed. The weight of the swollen gel after absorbing the liquid was divided by the weight of the original water-absorbing agent composition to calculate the suction amount (g / g) of the water-absorbing agent composition with respect to physiological saline.

(3) Aspiration amount for bovine blood Instead of physiological saline, bovine blood (cattle blood (freeze-dried product; Wako Code No. 029-07071: "Wako Pure Chemical Industries, Ltd.") was diluted with a predetermined amount of pure water. The amount of suction (g / g) for bovine blood was calculated in the same manner as the amount of suction for physiological saline described in (2) above, except that the dissolved amount was used.

(4) 2 g of the water-absorbent composition was placed in a fluid aluminum cup (bottom diameter 50 mm, height 23 mm) after moisture absorption, and kept in a thermo-hygrostat at 25 ° C. and 50% RH for 1.5 hours. After allowing to stand to absorb moisture, the aluminum cup was taken out, and the aluminum cup was tilted at an inclination angle of 30 ° to compare the fluidity of the water absorbing agent compositions after moisture absorption.

(5) Anti-corrosion effect and gel stability 1 g of the water-absorbent composition was added to 25 cc of physiological saline in a container with a polypropylene lid having a diameter of 55 mm and a height of 70 mm to swell the resulting gel. The iron clips were dipped so that they were sufficiently dipped, and allowed to stand at room temperature for 3 days to compare the formation of rust in the gel. At the same time, the gel stability was visually compared.

(6) Antistatic performance 10 g of the water-absorbent agent composition was used in a plastic bag with a zipper (Unipack E
-4: Production Made in Japan: 140 mm x 100 mm x 0.0
4 mm), the bag was closed, and the bag was shaken vigorously up and down for 1 minute, and the state of adhesion of the water absorbing agent composition inside the plastic bag was visually observed and evaluated.

(7) Amount of residual surface cross-linking agent (in the case of epoxy compound) 2.0 g of the water absorbing agent composition was added to a 100 ml beaker,
2 ml of a composition liquid consisting of methanol / water = 2/1% by weight is added, the container is covered and left for 1 hour. 5 ml of methanol was added to the beaker and filtered, 1.0 g of the filtrate was placed in a 50 ml eggplant flask, and 0.05 ml of 12 wt% aqueous nicotinamide solution was added. Attach the air-cooled tube to the eggplant-shaped flask and heat for 30 minutes in a boiling water bath. The reaction solution was filtered using filter paper, and the filtrate was analyzed by high performance liquid chromatography. On the other hand, the same operation was performed by adding a known amount of a cross-linking agent without using the water-absorbing agent composition, and the obtained calibration curve was used as an external standard, considering the dilution ratio of the filtrate, in the water-absorbing agent composition. The residual surface crosslinking agent amount (ppm) was determined.

(8) Absorption capacity under pressure The absorption capacity under pressure is measured using the apparatus shown in FIG. That is, the upper opening 2 of the buret 1 is capped 3 and the measuring table 4
And set the air port 5 at a constant height. The filter paper 7 is placed on the glass filter 6 having a diameter of 70 mm in the center of the measuring table 4. The non-woven fabric 8 is fixed to the lower end of the support cylinder 10 having a diameter of 55 mm, 0.76 g of the water-absorbent composition is evenly dispersed on the non-woven fabric 8, and a load 9 of 20 g / cm ² is further applied.
A value (Aml) of 0.9 wt% aqueous sodium chloride solution (physiological saline) absorbed by placing this non-woven fabric-water-absorbent composition-load together with the supporting cylinder on the filter paper 7 on the glass filter-6 for 30 minutes. Was measured and divided by the weight of the original water-absorbing agent composition (0.76 g) as shown in (Equation 2) to obtain the absorption capacity under pressure (ml / g).

[0080]

[Equation 2]

Reference Example 1 4.4 g of an internal cross-linking agent polyethylene glycol diacrylate was dissolved in 5500 g of an aqueous solution of sodium acrylate having a neutralization ratio of 75 mol% (monomer concentration: 33%). After degassing, 2.4 g of sodium persulfate and 0.12 g of 1-ascorbic acid were added to carry out polymerization. When the polymerization was completed, the obtained water-containing gel cross-linked polymer was further subdivided and dried in a hot air dryer at 150 ° C. until the water content of the water-containing gel cross-linked polymer was 5% or less. After crushing the dried product with a roll granulator, the ASTM 20 mesh wire mesh passing product is fractionated, and the water content is 400 μm in average particle size, and the proportion of the resin having a particle size of less than 150 μm is 4% by weight. A polymer (1) was obtained.

Reference Example 2 7 g of an internal cross-linking agent, trimethylolpropane triacrylate, was dissolved in 5500 g of an aqueous solution of sodium acrylate having a neutralization rate of 75 mol% (monomer concentration: 38%) and degassed with nitrogen gas. After the addition, 2.3 g of potassium persulfate and 0.11 g of 1-ascorbic acid were added to carry out polymerization. When the polymerization was completed, the obtained water-containing gel-like cross-linked polymer was further subdivided and dried in a hot air dryer at 150 ° C. until the water content of the water-containing gel-like cross-linked polymer was 5% or less. After crushing the dried product with a roll granulator, the ASTM 20 mesh wire mesh passing product is fractionated to give an irregular crushed water-absorbing property in which the ratio of the resin having an average particle size of 380 μm and a particle size of less than 150 μm is 5% by weight. A polymer (2) was obtained.

Reference Example 3 With respect to 100 parts of the water-absorbent polymer (1) obtained in Reference Example 1, 0.5 part of glycerin as the first crosslinking agent and 0.05 parts of ethylene glycol diglycidyl ether as the second crosslinking agent. Part, water 3 parts, and an aqueous liquid consisting of 0.75 parts of isopropyl alcohol were added and mixed, and the obtained mixture was heat-treated at 200 ° C. for 35 minutes to obtain an irregularly crushed water-absorbing polymer (3).

(Example 1) Water absorbing polymer (2) 100
Parts, sodium polyaspartate (molecular weight 10
000) 1 part and an aqueous liquid consisting of 5 parts of water were added and mixed to obtain a water absorbing agent composition (1) of the present invention.

(Example 2) Water absorbing polymer (1) 100
0.5 part by weight of glycerin as the first cross-linking agent, 0.05 part of ethylene glycol diglycidyl ether as the second cross-linking agent, 3 parts of water, and 0.75 of isopropyl alcohol.
Parts, sodium polyaspartate (molecular weight 5000)
An aqueous liquid consisting of 0.5 parts was added and mixed, and the resulting mixture was heat-treated at 200 ° C. for 33 minutes to obtain a water absorbing agent composition (2) of the present invention.

(Example 3) Water absorbing polymer (3) 100
5 parts by weight of polyaspartic acid (molecular weight 50,000)
Parts, 10 parts of polylysine hydrochloride (molecular weight 2000), and 1 part of sodium polyglutamate (molecular weight 100000) are each added by dry blending to obtain the water-absorbing agent compositions (3), (4) and (5) of the present invention. It was

(Example 4) Water absorbing composition (1) of the present invention
To (5) and comparative water absorbent compositions (1) to (3), the water-absorbent polymers (1) to (3) are used, and the absorption amount at normal pressure for physiological saline solution, the suction amount for physiological saline solution, Table 1 shows the measurement results of the suction amount for bovine blood, the fluidity after moisture absorption, the anticorrosive effect, and the antistatic performance. It can be seen that the water absorbent composition of the present invention is also excellent in hygroscopic fluidity, antirust effect, antistatic performance and the like.

(Example 5) Water absorbing composition (1) of the present invention
100 parts and 100 parts of crushed pulp are dry-mixed, then air-paper-formed and compressed to have a density of 0.15 g / cc and a basis weight of 0.05 g.
A water-absorbent structure (1) of the present invention of / cm 2 was obtained.

Example 6 Except that the water absorbent composition (1) in Example 5 was replaced with the water absorbent compositions (2) to (5) and the comparative water absorbent compositions (1) to (3). Is Example 5
Similarly to the above, the water absorbent structures (2) to (5) of the present invention having a density in the range of about 0.13 to 0.17 g / cc and a basis weight of 0.047 to 0.053 g / square centimeter and the comparison Water absorbent structures (1) to (3) were obtained.

(Example 7) From the water-absorbent structures (1) to (5) and the comparative water-absorbent structures (1) to (3) obtained in Examples 5 and 6, respectively, a water-absorbent structure having a diameter of 5 cm was obtained. The body was punched out, and each was used as a sample piece. When 10 cc of bovine blood was dropped onto each of the sample pieces, all the water-absorbent structures of the present invention showed better results in the absorption rate than the comparative water-absorbent structures. As is apparent from these results, the water-absorbing structure containing the water-absorbing agent composition of the present invention shows an excellent absorption amount for bovine blood, and the water-absorbing structure of the present invention has been developed so far. Therefore, it is possible to provide an excellent absorbent article that does not have such a structure. (Example 8) 75 parts of the water-absorbent agent composition (1) of the present invention was pulverized with 25 parts of thermoplastic pulp (ES fiber: manufactured by Chisso Corporation: 1.5d, 10).
(10 mm) were dry-mixed, air-pressed and heat-compressed to obtain a water-absorbent structure (6) of the present invention having a density of 0.18 g / cc and a basis weight of 0.05 g / cm 2.

(Example 9) In place of the water absorbent composition (1) of the present invention in Example 8, the absorption amount at normal pressure for physiological saline solution, the suction amount for physiological saline solution, and the suction amount for bovine blood were changed. Using different water absorbent compositions, the same operation as in Example 8 was carried out, and the water absorbent structures (7) to (8) and the comparative water absorbent structure (4) of the present invention having substantially the same density and basis weight were obtained. ~ (6) was created.

(Example 10) The water-absorbing structures (6) to (8) of the present invention and the comparative water-absorbing structures (4) to (6) obtained in Examples 8 and 9 were used. Absorbent articles (1) to (3) and comparative absorbent articles (1) to (3) were prepared by the following operations. That is, liquid-permeable polypropylene topsheet, 2 sheets of tissue paper, 12c
Water-absorbent structure cut into mx 40 cm (weight approx. 24
g), a disposable diaper consisting of a liquid impermeable polyethylene backsheet with leg gathers and waist gathers and two tape fasteners was hand assembled by fastening the individual components with double sided tape.
The total weight of the diaper was about 45 g.

(Example 11) Absorbent articles (1) to (3) of the present invention obtained in Example 10 and comparative absorbent article (1).
Each of 30 (30) of (3) was randomly attached to 10 babies and monitored. After the test, each absorbent article was collected, and the leakage rates were compared, and the results are shown in Table 2. From this result, it is clear that in the water-absorbent structure containing the water-absorbent agent composition at a relatively high concentration, even if the suction amount for physiological saline is 14 g / g or more, the suction amount for bovine blood is 7 g / Those less than g do not show satisfactory performance. Therefore, the present invention also provides a means for selecting a water-absorbing agent composition effective for improving the performance of an absorbent article containing the water-absorbing agent composition in a high concentration.

(Example 12) With respect to 100 parts of the water-absorbent polymer (1) obtained in Reference Example 1, 0.5 part of glycerin was used as the first crosslinking agent and 0.05 parts of ethylene glycol diglycidyl ether was used as the second crosslinking agent. Part, water 3 parts, isopropyl alcohol 0.75 part, and polyaspartic acid (molecular weight 10000) 0.5 part were added and mixed, and the resulting mixture was heat treated at 200 ° C. for 33 minutes to give the present invention. A water absorbent composition (6) was obtained. The results of measuring the absorption capacity, the absorption capacity under pressure, the suction amount for physiological saline, the suction amount for bovine blood, and the residual epoxy crosslinking agent amount of the obtained water absorbing agent composition (6) are shown in Table 3. The composition (6) has excellent physical properties and the residual epoxy crosslinking agent content is 2
It was very low as ppm.

Comparative Example 1 Comparative water absorbing agent composition (4) was obtained by carrying out surface cross-linking of water absorbing polymer (1) in the same manner as in Example 12 except that polyaspartic acid was not used. Various physical properties of the obtained comparative water-absorbing agent composition (4) are shown in Table 3. In comparison with the water-absorbing agent composition (6) using polyaspartic acid, the physical properties such as the absorption amount under pressure are inferior. However, the residual epoxy crosslinking agent was very high at 15 ppm.

Example 13 To 100 parts of the water-absorbing polymer (3) obtained in Reference Example 3, 5 parts of polyaspartic acid (molecular weight 50000) and 1 part of polyglutamic acid (molecular weight 100000) were added to 10 parts of water. After being dissolved and added and mixed as an aqueous solution, the obtained mixture was dried at 120 ° C. to obtain water-absorbing agent compositions (7) and (8) of the present invention.
Physical properties of the resulting water absorbent compositions (7) and (8) are shown in Table 3, and the water absorbent polymer (3) containing no polyamino acid.
Compared with the above, the amount of sucked bovine blood was significantly improved, and the residual epoxy crosslinking agent was significantly reduced to 5 ppm. As in the case of Example 4 described above, the water-absorbing polymer (3) was evaluated as a comparative water-absorbing agent composition (3) for comparison, and various physical properties thereof are shown in Table 3.

Example 14 In Reference Example 2, 104.5 g (5% based on the solid content of the monomer) of sodium polyaspartate (molecular weight 10,000) was dissolved in the aqueous solution of sodium acrylate to dissolve the monomer at the time of polymerization. Sodium polyaspartate was added to. Less than,
Polymerization was carried out in the same manner as in Reference Example 2, and then similarly hydrogel-like crosslinked polymer was subdivided, dried and pulverized to give a water absorbing composition (9) containing sodium polyaspartate.
Got The water-absorbing agent composition (9) obtained had almost the same absorption capacity as compared with the water-absorbing polymer (2) in which sodium polyaspartate was not used for polymerization, but the fluidity after moisture absorption, the rust preventive effect, The gel stability and antistatic performance were excellent, and the water-soluble component by pH titration was about 4% by weight less than that of the water-absorbent polymer (2), which was good.

(Example 15) In Example 14, the amount of sodium polyaspartate dissolved in the sodium acrylate aqueous solution was 23 g (based on the monomer solid content of 1 g).
%) To obtain a water absorbing agent composition (10) containing sodium polyaspartate.
The water-absorbing agent composition (10) obtained had almost the same absorption capacity as compared with the water-absorbing polymer (2) in which sodium polyaspartate was not used for the polymerization, but the fluidity after moisture absorption,
The anticorrosion effect, gel stability, and antistatic performance were slightly excellent, and the water-soluble component by pH titration was about 2% by weight less than that of the water-absorbent polymer (2).

[0099]

The effect of the polyamino acid (salt) in the water absorbent composition of the present invention is not clear, but there is no problem in terms of safety and hygiene of the polyamino acid (salt), and a small amount is added to the water absorbing polymer. A new water-absorbing agent composition that is excellent in absorption characteristics of body fluids such as urine, blood, and secretory fluid, particularly in blood absorption specificity, and also excellent in gel stability, fluidity after moisture absorption, antistatic performance, and anticorrosive effect. It is to provide things.
Further, in the surface cross-linking of the water-absorbent polymer, the polyamino acid (salt) also has an excellent effect of improving various physical properties, and also provides a water-absorbing agent composition in which the residual surface cross-linking agent is significantly reduced.

Therefore, the water-absorbent composition of the present invention can be used as a diaper, a sanitary napkin, and an absorbent article for body fluids such as jigs and wound protection materials for incontinent persons, wound healing materials, or biotechnology applications. It is preferably applied to, and greatly contributes to the development of this industry.

[0101]

[Table 1]

[0102]

[Table 2]

[0103]

[Table 3]

[Brief description of drawings]

FIG. 1 is a device for absorption capacity under pressure used in the present invention. (Explanation of symbols) 1 ... Bullet 2 ... Buret upper end 3 ... Plug 4 ... Measuring stand 5 ... Air intake 6 ... Glass filter 7 ... Filter paper 8 ...・ Nonwoven fabric 9 ・ ・ ・ Load 10 ・ ・ ・ Supporting cylinder

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ishi ▲ Saki ▼ Kunihiko 1 992, Nishi-oki, Akihama, Aboshi-ku, Himeji-shi, Hyogo Prefecture, Nihon Catalyst Co., Ltd. 1 Nishi-oki No. 992 Address, Nippon Shokubai Co., Ltd., Polymer Research Laboratory (56) References JP-A-7-216101 (JP, A) JP-A-7-224163 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) C08L 1/00-101/16

Claims (8)

(57) [Claims] 1. A polymer obtained by polymerizing a water-soluble unsaturated monomer.
A water absorbing agent composition containing a water absorbing polymer having a cross-linked structure
A water-absorbing agent composition comprising a polyamino acid (salt) and a water-absorbing polymer. Wherein said polyamino acid (salt), poly aspartic acid (salt), polyglutamic acid (salt), polylysine water absorption in claim 1 is at least one selected from (salts) serial <br/> mounting Agent composition. 3. Obtained by polymerizing a water-soluble unsaturated monomer.
A water absorbing agent composition containing a water absorbing polymer having a cross-linked structure
Therefore, the vicinity of the surface of the water-absorbent polymer is further cross-linked.
The physiological saline solution of the water absorbing agent composition (0.9 wt% sodium chloride
Amount of absorption for 60 minutes at atmospheric pressure for at least 25 g / g for aqueous thorium solution, 1 for 20 ml of physiological saline
At least 14g / g of suction volume for 0 minutes and 20 bovine blood
A water absorbing agent composition having a suction amount for 10 minutes per ml of at least 7 g / g. 4. 20 g / cm ² of the water absorbent composition (about
Absorption <br/> yield ratio of 30 minutes under pressure in corresponding to 1.96 kPa) is, water-absorbent agent composition according to any one of claims 1 to 3 is 30 ml / g or more with respect to physiological saline. 5. Obtained by polymerizing a water-soluble unsaturated monomer
Water-absorbing agent composition containing water-absorbing polymer having cross-linked structure
A method for producing a water-absorbing agent composition, which comprises adding and mixing a polyamino acid (salt) aqueous solution to a carboxyl group-containing water-absorbing polymer having a crosslinked structure . 6. The method of claim wherein the aqueous solution comprising a crosslinking agent capable of further reacting with Cal <br/> Bokishiru group water-absorbing polymer 5
A method for producing the described water-absorbing agent composition. 7. A polymer obtained by polymerizing a water-soluble unsaturated monomer.
Water-absorbing agent composition containing water-absorbing polymer having cross-linked structure
A method for producing a water-absorbing agent composition, which comprises polymerizing a water-soluble unsaturated monomer in the presence of a polyamino acid (salt) and a crosslinking agent. 8. A claim 1 water-absorbent agent composition 10 to 95 parts by weight and hydrophilic fibers 90 to 5 parts by weight according to any of the 4
An absorbent article comprising a water-absorbing structure containing the same .