JPH0596159A - Water absorbing body and its production, and water absorbing agent and its production - Google Patents

Abstract

PURPOSE:To provide a water-absorbing body being physically and chemically stable, in which migration or falling in a cellulosic fiber of a water absorptive resin grain hardly occurs, therefore having excellent absorptivity. CONSTITUTION:The water absorptive body contains absorptive resin grains having an acid group such as carboxylic group at the surface, cellulosic fiber and a cationic high molecular compound of >=200wt. average molecular wt., and the water-absorptive resin grains are stuck to a cellulose powder by a cationic high molecular compound in the presence of water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel water absorbing body and a method for producing the same. More specifically, the present invention relates to a novel water absorbent that is composed of a mixture of cellulose fibers and water absorbent resin particles and is chemically and physically stable even after absorbing liquid, and a method for producing the same. The present invention relates to a novel water absorbing agent, an absorber containing the same, and a method for producing them. More specifically, the present invention relates to a novel water-absorbing agent, which has excellent water-absorbing properties by itself, and exhibits an extremely excellent effect when compounded with a cellulose fiber, an absorber containing the same, and a method for producing them.

[0002]

2. Description of the Related Art In recent years, a water-absorbent resin that absorbs several tens to several hundreds of times its own weight of water has been developed, and in the fields of sanitary materials such as sanitary products and disposable diapers, agricultural and horticultural fields, foods for keeping freshness, etc. Various water-absorbent resins have been used for applications requiring water absorption or water retention, such as fields, industrial fields such as dew condensation prevention, and cold insulation materials. As the water-absorbent resin, a cross-linked acrylate polymer or a cross-linked starch-acrylate graft polymer is known.

Since the water-absorbent resin is generally in powder form,
It is rarely used alone, is mixed with hydrophilic cellulose fibers such as crushed pulp and paper, and is used as a water absorbent for diapers (US Pat. No. 38882).
57). In applications where a large amount of water is absorbed in a short period of time, such mixing is particularly necessary in order to prevent the water-absorbing resin alone from being absorbed in a short period of time and preventing the water from spreading. Cellulose fiber retains a powdery water-absorbent resin, or it takes time for the water-absorbent resin to absorb ambient water, and thus retains water around the water-absorbent resin particles before that, or , Has a function of evenly distributing water to the water-absorbent resin particles distributed by the capillary phenomenon.

[0004]

However, when the water absorbent obtained by the above-mentioned known technique is used, for example, as a water absorbent of a paper diaper, when the ratio of the water absorbent resin particles becomes high, the binding force between the cellulose fibers becomes large. Due to its weakness, the swelled water-absorbent resin may move or fall off after absorbing urine during actual use, resulting in a problem that the water-absorbing performance is not as high as expected, and water-absorbent resin particles due to certain components in urine. However, there was a problem that the performance as designed was not obtained due to the decomposition of

The present invention provides a water-absorbing material which is physically and chemically stable, and in which the water-absorbent resin particles do not easily move or fall off in the cellulose fiber, and therefore have excellent water-absorbing properties. The task is to do. Another object of the present invention is to provide a method for easily producing such a water absorbing body.

[0006]

In order to solve the above problems, the present invention comprises water-absorbent resin particles having an acidic group on the surface, cellulose fibers and a cationic polymer compound having a weight average molecular weight of 2000 or more. And a water absorbent body. This water absorbent may be a mixture of water absorbent resin particles, cellulose fibers and a cationic polymer compound.

In order to solve the above problems, the present invention also provides a water-absorbing agent obtained by treating water-absorbing resin particles having an acidic group on the surface with a cationic polymer compound having a weight average molecular weight of 2000 or more, and Provided is a water absorber comprising cellulose fibers. This water absorber may be a mixture of a water absorbing agent and cellulose fibers. In order to solve the above problems, the present invention mixes water-absorbent resin particles having an acidic group on the surface, cellulose fibers and a cationic polymer compound having a weight average molecular weight of 2000 or more in a gas phase, and mixing the mixture with the gas phase. Provided is a method for producing a water absorber for papermaking.

In order to solve the above problems, the present invention also provides a water-absorbing agent obtained by treating water-absorbent resin particles having an acidic group on the surface with a cationic polymer compound having a weight average molecular weight of 2000 or more, and cellulose. Provided is a method for producing a water absorbent body, in which fibers are mixed in a gas phase and the mixture is formed into a paper in the gas phase. This invention is a water-absorbing agent characterized by comprising a water-absorbing cross-linked polymer and a polyamide polyamine epihalohydrin resin; a method for producing a water-absorbing agent characterized by mixing a water-absorbing cross-linked polymer with a polyamide polyamine epihalohydrin resin; An absorbent body comprising a water absorbing agent of the present invention and a cellulose fiber; and a method for producing an absorbent body, which comprises dry-mixing the water absorbing agent of the present invention and a cellulose fiber, and then compressing the obtained mixture. Is.

The water absorbent resin which can be used in the present invention is required to have an acidic group. Examples of such an acidic group include a carboxyl group. Examples of the water absorbent resin having a carboxyl group on the surface include, for example, acrylate cross-linked polymer, vinyl alcohol-acrylate cross-linked copolymer, starch-acrylate cross-linked polymer, maleic anhydride grafted polyvinyl alcohol. Examples thereof include crosslinked products and carboxymethylcellulose alkali salt crosslinked products, which are preferably used in the present invention. The amount of acidic groups contained in the water absorbent resin is not particularly limited, but the water absorbent resin 1
It is preferable that 0.01 equivalent or more of the acidic group be present per 00 g. Suitable water-absorbent resin particles are, for example, JP-A-57-34101, JP-B-58-35605, JP-B-62-16135, and JP-B-2-143.
61, JP 62-144748 A, JP 62-54751 A, JP 63-21902 A, and the like. Particularly preferred are acrylate cross-linked polymer particles having a neutralization degree of 50 to 95 mol% from the viewpoint of water absorption performance, and the polymerization method is not particularly limited.

The shape of the water-absorbent resin particles used in the present invention may be spherical, scaly, pulverized amorphous or granular. The size of the particles is preferably in the range of 10 to 1000 μm, more preferably in the range of 20 to 840 μm. Particles of less than 10 μm may cause so-called gel blocks when the water-absorbent resin particles in the water absorbent swell, and particles of more than 1000 μm may give the water absorbent a rugged feel during use.

In the present invention, a method of mixing the water absorbing agent obtained by previously treating the surface of the water absorbent resin particle with the cationic polymer compound and the cellulose fiber may be used, but a step of previously treating the surface of the water absorbent resin particle is provided. However, the water-absorbent resin particles, a method of mixing the cationic polymer compound and the cellulose fiber or a method of mixing the cellulose fiber previously treated with the cationic polymer compound and the water-absorbent resin particles may be the same. The effect can be obtained.

The cationic polymer compound used in the present invention is a compound capable of reacting with an acidic group such as a carboxyl group of a water absorbent resin to form an ionic bond,
And a cationic polymer compound having a weight average molecular weight of at least 2000, and a weight average molecular weight of 5,000.
The above is preferable, and the one having a weight average molecular weight of 10,000 or more is more preferable. Weight average molecular weight 20 used in the present invention
The cationic polymer compound of 00 or more is not limited to those showing a single maximum value (peak) in the molecular weight analysis by gel permeation chromatography, and a weight average even if it shows a plurality of maximum values (peak). Molecular weight is 2000
The above is sufficient. If a cationic polymer compound having a weight average molecular weight of less than 2000 is used, or if an anionic polymer compound or a nonionic polymer compound is used without using the cationic polymer compound, the adhesion to the cellulose fiber is insufficient and water absorption is caused. There is a problem that the water absorbent resin sometimes moves or falls off.

In the present invention, as the cationic polymer compound, a compound containing at least one selected from a primary amino group, a secondary amino group, a tertiary amino group and salts thereof is preferably used. In this case, the salt of amino group is a salt of amino group nitrogen neutralized with an inorganic acid or an organic acid. Examples of the inorganic acid that can be used for neutralization include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid and the like,
Examples of the organic acid include formic acid, acetic acid, propionic acid, p-toluenesulfonic acid and the like.

Specific examples of the cationic polymer compound include, for example, polyethyleneimine, modified polyethyleneimine crosslinked with epihalohydrin to a water-soluble range, polyamine, polyamidoamine modified by grafting ethyleneimine, and protonated polyamide. Amine, polyether amine, polyvinyl amine, modified polyvinyl amine, polyalkyl amine, polyamide polyamine epihalohydrin, polyvinyl imidazole, polyvinyl pyridine, polyvinyl imidazoline, polyvinyl tetrahydropyridine, polydialkylaminoalkyl vinyl ether, polydialkylaminoalkyl (meth) acrylate, poly Cationic polyelectrolytes such as allylamine and salts thereof.

The amount of the cationic polymer compound used is preferably 0.1 to 3 relative to 100 parts by weight of the water absorbent resin particles.
It is in the range of 0 parts by weight, more preferably in the range of 0.3 to 20 parts by weight, and most preferably in the range of 0.5 to 10 parts by weight. If the amount of the cationic polymer compound is less than 0.1 parts by weight, the water-absorbent resin may not be sufficiently modified, and if the amount exceeds 30 parts by weight, the effect corresponding to the added amount cannot be obtained. In some cases, it is also economically disadvantageous. The cationic polymer compound is water-soluble, powder,
It is used in the form of being dissolved in an aqueous solution, a mixed solvent of water and a hydrophilic organic solvent such as ethanol, or in the form of reacting with water-absorbent resin particles.

There are no particular restrictions on the means for incorporating the cationic polymer compound into the water absorbent body, as long as the cationic polymer compound can be arranged so as to serve as a binder for the water-absorbent resin particles and the cellulose fibers. The cationic polymer compound may be added as a powder as it is, and after being dissolved or dispersed in a vehicle such as water or an organic solvent to form a liquid substance, the liquid substance is sprayed or immersed in the liquid substance. Alternatively, a method of drying to remove the vehicle may be used if necessary. A preferred method is to obtain a water-absorbing agent by previously mixing the water-absorbing resin particles and the cationic polymer compound to obtain a water-absorbing agent having the surface of the water-absorbing resin particles treated, and further dry-mixing this with cellulose fibers to obtain a water-absorbing material. Is. For mixing the water-absorbent resin particles and the cationic polymer compound, for example, an apparatus such as a high speed stirring mixer, an air flow mixer, a tumbling mixer, a kneader or the like can be used. During the mixing, it is possible to coexist with an organic powder such as cellulose powder or an inorganic powder such as fine particle silica. Further, the treated water-absorbent resin particles may be dried if necessary.

The treatment of the water-absorbent resin particles with the cationic polymer compound is carried out, for example, by mixing the water-absorbent resin particles and the cationic polymer compound in the presence of water and contacting them for 10 seconds to 60 minutes. .. Alternatively, water or an aqueous liquid is added after previously mixing the water-absorbent resin particles and the cationic polymer compound particles, the water-absorbent resin particles,
By mixing the cationic polymer compound particles and the cellulose fiber in advance and then adding water or an aqueous liquid, the reaction between the water absorbent resin particles and the cationic polymer compound can be caused. In the latter case, the addition of water or the like does not necessarily have to be performed prior to the use of the water-absorbing material, and it is also possible to absorb water when using the water-absorbing material. The treatment with the molecular compound and the fixation with the cellulose fiber occur simultaneously when the water absorbent is used.

In the present invention, the aqueous liquid containing the cationic polymer compound, water, or the aqueous liquid containing no cationic polymer compound is mixed with the water-absorbent resin particles in various forms. For example, the water-absorbent resin particles are dipped in the liquid, mixed with the liquid droplets, or sprayed with the liquid to form a mist and mixed. Polyamide polyamine epihalohydrin resin used in the present invention,
For example, a resin obtained by reacting a condensation polymer of a polyalkylene polyamine and a polycarboxylic acid with epihalohydrin, and more specifically, a polyamide polyamine epichlorohydrin resin obtained by reacting a condensation product of diethylenetriamine and adipic acid with epichlorohydrin can be exemplified.

In the present invention, the amount of the polyamide polyamine epihalohydrin resin is preferably in the range of 0.01 to 30 parts by weight based on 100 parts by weight of the dried water-absorbing crosslinked polymer. The range is more preferably 0.1 to 20 parts by weight, and most preferably 0.5 to 10 parts by weight. If the amount is less than 0.01 part by weight, the water-absorbing crosslinked polymer may not be sufficiently modified, and if the amount exceeds 30 parts by weight, the effect corresponding to the added amount may not be obtained. It is also economically disadvantageous.

The water absorbing agent of the present invention can be obtained by adding and mixing a polyamide polyamine epihalohydrin resin to a water-absorbing crosslinked polymer. The time of addition to the water-absorbing cross-linked polymer is not particularly limited as long as it does not hinder the manufacturing process of the water-absorbing agent, and for example, to the water-absorbing cross-linked polymer in the state of hydrous gel, or drying this After that, it is also possible to add and mix after performing dry pulverization or in the granulation step. At this time, the mixing is preferably performed in the presence of water. Therefore, the polyamide polyamine epichlorohydrin resin is more preferably added to and mixed with the water-absorbing crosslinked polymer in the state of an aqueous solution. In the present invention, the aqueous solution containing the polyamide polyamine epichlorohydrin resin can be added under various mixing conditions such as an aqueous solution form, a droplet form, and a mist (microdroplet). Further, a hydrophilic organic solvent such as ethanol may be included in the aqueous solution. To mix the water-absorbing crosslinked polymer and the polyamide polyamine epihalohydrin resin,
Devices such as a high speed stirring mixer, an air flow mixer, a tumbling mixer, and a kneader can be used. During the mixing, it is possible to coexist with an organic powder such as cellulose powder or an inorganic powder such as fine particle silica. Further, the obtained water absorbing agent may be dried if necessary.

In order to obtain a water absorbent body from the above water-absorbent resin particles (or water-absorbing agent) and cellulose fibers, for example, a method in which the water-absorbent resin particles are sprinkled on a paper or mat made of cellulose fibers and sandwiched between them if necessary, Known means for obtaining a water absorbent body can be appropriately selected, such as a method of uniformly blending cellulose fibers and water-absorbent resin particles. Preferred is a method in which the water-absorbent resin particles and the cellulose fibers are mixed in a gas phase (so-called dry mixing), and then paper-making is performed in the gas phase, followed by compression. By this method, it is possible to remarkably prevent the water absorbent resin particles from falling off from the cellulose fibers. The compression may be performed under heating, and the temperature range is, for example, 50 to 200 ° C.

Cellulose fibers that can be used in the present invention include, for example, mechanical pulp from wood,
Examples thereof include wood pulp fibers such as chemical pulp, semi-chemical pulp and dissolving pulp, and artificial cellulose fibers such as rayon and acetate. A preferred cellulose fiber is wood pulp fiber. These cellulose fibers may partially contain synthetic fibers such as polyethylene, polypropylene, nylon and polyester.

The water absorbent body of the present invention comprises the water absorbent resin particles 10
˜95% by weight and cellulose fibers 5 to 90% by weight (total 100% by weight of water-absorbent resin particles and cellulose fibers). In particular, in the range where the ratio of the cellulose fibers is low (for example, 5 to 60% by weight), the weight of the water absorber is 1/2 to 1/3 lighter than that of the conventional one (80 to 90% by weight of the cellulose fibers). And exhibits the same or higher water absorption performance. The water absorbent body of the present invention can have a density of 0.01 to 0.50 g / cm ³ , for example.

The water absorber of the present invention is not limited by its shape or the distribution state of each component in the water absorber.
Therefore, it is possible to adopt a conventionally known method adopted to obtain a water absorbent having a shape convenient for use in a disposable diaper, a sanitary napkin, etc., for example, a sheet shape or a web shape. In the present invention, the water-absorbent resin particles may be treated with, for example, a cross-linking agent that cross-links the surface of the water-absorbent resin particles with a covalent bond before the treatment with the cationic polymer compound. In the process of researching the water absorbent of the present invention, the inventors have found a novel method for producing a water absorbent having excellent water absorbing properties and also having excellent affinity with cellulose fibers. Such a water-absorbing agent is obtained by treating the surface of a water-absorbent resin particle having an acidic group with a cross-linking agent having two or more functional groups capable of reacting with the acidic group to form a covalent bond to form a part of the acidic group. Weight average molecular weight of 2 which is capable of forming an ionic bond by reacting the particles with an acidic group.
It can be obtained by the method for producing a water-absorbing agent which is mixed with 000 or more cationic polymer compounds. During this treatment, the covalently crosslinked layer must not be bonded to all the acidic groups on the particle surface, and some acidic groups must be left for ionic crosslinking. The amount of the crosslinking agent used is appropriately in the range of 0.01 to 10 parts by weight with respect to 100 parts by weight of the water absorbent resin. If the amount of the cross-linking agent is less than 0.01 parts by weight, the crosslinking may be insufficient, and if it exceeds 10 parts by weight, the residual amount of the acidic groups capable of ionic bonding may be insufficient. In the step of forming the crosslinked layer by this covalent bond, the amount of the aqueous liquid containing the crosslinking agent does not cover all the surfaces of the water absorbent resin particles (for example, the weight ratio of the crosslinking agent to the water absorbent resin is within the above range). It is important that they are used in different amounts and mixed. The mixture of the water-absorbent resin particles and the cross-linking agent is heat-treated at a temperature in the range of 40 to 250 ° C for 1 to 120 minutes to form a cross-linked layer by covalent bonds on the surface of the water-absorbent resin particles. Mixing the aqueous liquid containing the cross-linking agent and the water-absorbent resin particles can be carried out in various forms (for example, immersing the particles in an aqueous solution of the cross-linking agent, mixing droplets of the aqueous solution with the particles, or spraying the aqueous solution). It is carried out by forming a mist and mixing it with particles). For this mixing, for example,
Devices such as a high speed stirring mixer, an air flow mixer, a tumbling mixer, and a kneader can be used. During the mixing, it is possible to coexist with an organic powder such as cellulose powder or an inorganic powder such as fine particle silica. The water-absorbent resin particles after the treatment may be dried if necessary.

The cross-linking agent is not particularly limited as long as it is a compound having two or more functional groups capable of reacting with the acidic groups of the water absorbent resin to form a covalent bond, and the two or more functional groups. The groups need not be the same as each other. Examples of such a functional group include an epoxy group, an aldehyde group,
Examples include hydroxyl groups. As the cross-linking agent, for example,
Polyglycidyl ethers such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether and glycerin triglycidyl ether; haloepoxy compounds such as epichlorohydrin and α-methylchlorohydrin; polyaldehydes such as glutaraldehyde and glyoxal; glycerin, pentaerythritol, Examples thereof include polyols such as ethylene glycol and polyethylene glycol, which may be used alone or in combination of two or more kinds. The cross-linking agent is preferably water-soluble, and is used in the form of being dissolved in an aqueous solution or a mixed solvent of water and a hydrophilic organic solvent such as ethanol.

The water-absorbing material of the present invention is less likely to fall off from the cellulose fiber, move in the cellulose fiber or decompose the water-absorbing resin particle even after the water-absorbing resin particle absorbs water and swells. It has excellent properties and can be used for various purposes. Examples of fields of use include the following. (1) Water absorbent body for absorbent articles Paper diapers, sanitary napkins, incontinence pads, medical pads and the like.

(2) Absorbent / water-retaining body for agricultural and horticultural use Substitutes for water moss, soil reforming / improving materials, water-retaining materials, agricultural chemical efficacy sustaining materials, etc. (3) Water absorbers for construction Dew condensation prevention materials for interior wall materials, cement curing materials, etc. (4) Others Release control materials, cold insulation materials, disposable body warmers, sludge coagulation materials, food freshness retention materials, drip absorption materials, etc.

[0028]

When the cationic polymer compound, the water absorbent resin particles and the cellulose fiber are contained in the presence of water, the cationic polymer compound acts as a binder (binder) between the water absorbent resin particle and the cellulose fiber. Because it works like
The water-absorbent resin particles adhere to the cellulose fibers via the cationic polymer compound. By sticking in this way, it becomes difficult for the water-absorbent resin particles to move in the cellulose fibers or drop out from the cellulose fibers even when absorbing water. Moreover, decomposition of the water absorbent resin can be prevented.

[0029]

EXAMPLES Specific examples and comparative examples of the present invention will be shown below, but the present invention is not limited to the following examples.
In the following, mere “%” means “% by weight” and “part” means “part by weight”. -Synthesis example of water absorbent resin- Sodium acrylate 74.95 mol%, acrylic acid 2
37% of acrylate type monomer consisting of 5 mol% and 0.05 mol% of trimethylolpropane triacrylate
% Aqueous solution of 4000 parts was polymerized with 2.0 parts of ammonium persulfate and 0.08 parts of L-ascorbic acid in a nitrogen atmosphere at 30 to 80 ° C. to obtain a gel-like water-containing crosslinked polymer. The resulting hydrogel crosslinked polymer was dried with a hot air dryer at 150 ° C., crushed with a hammer mill, and sieved with a 20 mesh (Tyler's standard sieve. The same applies below) wire mesh to obtain a 20 mesh passing product. .. This is called water-absorbent resin particle (a).

-Production Example 1- 100 parts of the water-absorbent resin particles (a) was mixed with glycerin of 0.
After 5 parts, 2 parts of water and 2 parts of ethyl alcohol were added and mixed, the mixture was heated at 210 ° C. for 10 minutes to obtain a water-absorbing polymer A in which the vicinity of the surface was secondarily crosslinked. Further, with respect to 100 parts of the resulting water-absorbent polymer A, polymine SK (modified polyethyleneimine, weight average molecular weight of about 100,000, BASF
20% aqueous solution) (manufactured by the same company) was added and mixed, heated and dried at 120 ° C. for 10 minutes, and sieved with a 20 mesh sieve to obtain a 20-mesh passed product. Water absorbent (1-
Say 1).

-Production Example 2- 100 parts of the water-absorbent polymer A obtained in Production Example 1,
15 parts of Polymin SN (modified polyethyleneimine, weight average molecular weight of about 100,000, manufactured by BASF, 20% aqueous solution) is spray mixed, dried by heating at 120 ° C. for 10 minutes, sieved with a 20 mesh sieve and passed through 20 mesh. I got a thing. This is called a water absorbing agent (1-2).

-Preparation Example 3-For 100 parts of the water-absorbent polymer A obtained in Preparation Example 1,
A water absorbing agent (1-3) was obtained by adding and mixing 5 parts of a 30% aqueous solution of Epomin P-1000 (polyethyleneimine, weight average molecular weight of about 70,000, manufactured by Nippon Shokubai Co., Ltd.). -Production Example 4-Epomin P-1 was added to 100 parts of the water-absorbent resin particles (a).
000 (polyethyleneimine, weight average molecular weight of about 70,000,
33.4 parts of a 30% aqueous solution (made by Nippon Shokubai Co., Ltd.) was added and mixed, and the mixture was dried by heating at 120 ° C. for 20 minutes and sieved with a 20 mesh sieve to obtain a 20 mesh passed product. This is called a water absorbing agent (1-4).

-Preparation Example 5-For 100 parts of the water-absorbent polymer A obtained in Preparation Example 1,
A water absorbing agent (1-5) was obtained by adding 1.7 parts of a 30% aqueous solution of Epomin P-1000 (polyethyleneimine, weight average molecular weight of about 70,000, manufactured by Nippon Shokubai Co., Ltd.). -Production Example 6-For 100 parts of the water-absorbent polymer A obtained in Production Example 1,
10 parts of a 30% aqueous solution of Epomin SP-200 (polyethyleneimine, weight average molecular weight of about 10,000, manufactured by Nippon Shokubai Co., Ltd.) was added and mixed, and after heating and drying at 120 ° C. for 20 minutes, it was sieved with a 20 mesh sieve. 20 mesh pass particles were obtained. This is called a water absorbing agent (1-6).

-Production Example 7-To 100 parts of the water-absorbent resin particles (a), 8 parts of a 10% aqueous solution of ethylene glycol diglycidyl ether (Denacol EX-810 manufactured by Nagase Kasei Co., Ltd.) was added and mixed, and then 120 Heat treatment was performed at 30 ° C. for 30 minutes to obtain a water-absorbent polymer B in which the vicinity of the surface was secondarily crosslinked. The property of the water-absorbent polymer B was powder. Further, the resulting water absorbent polymer B1
Dimethylaminoethyl acrylate-
Acrylamide-acrylic acid copolymer powder (dimethylaminoethyl acrylate / acrylamide / acrylic acid = 30/60/10 molar ratio, weight average molecular weight about 10
3 parts by weight of a product passing through 100,000 mesh) was added and mixed to obtain a water absorbing agent (1-7).

-Production Example 8-The water-absorbent polymer A obtained in Production Example 1 was classified with 60 to 100 mesh to obtain a water-absorbent polymer C (particle size 250 to 149 μm).
m) was obtained. Furthermore, 3 parts of Epomine P-1000 (polyethyleneimine, weight average molecular weight of about 70,000, manufactured by Nippon Shokubai Co., Ltd.) was added to 100 parts of the obtained water-absorbent polymer C.
Add 10 parts of 0% aqueous solution, mix, heat and dry at 120 ° C. for 10 minutes, and sift through a 20-mesh screen to 20
A mesh pass product was obtained. This is called a water absorbing agent (1-8).

-Production Example 9- The water-absorbent polymer A obtained in Production Example 1 was classified with 100 mesh to obtain a water-absorbent polymer D (particle size 149 μm or less). Further, 10 parts of a 30% aqueous solution of Epomine P-1000 (polyethyleneimine, weight average molecular weight of about 70,000, manufactured by Nippon Shokubai Co., Ltd.) was added to 100 parts of the resulting water-absorbent polymer D and mixed, and at 120 ° C. After heating and drying for 10 minutes, it was sieved with a 20-mesh sieve to obtain a 20-mesh pass product. This is called a water absorbing agent (1-9).

-Production Example 10-For 100 parts of the water-absorbent polymer A obtained in Production Example 1,
7.5 parts of a 40% aqueous solution of polyallylamine hydrochloride (PAA-HCL-10L, weight average molecular weight of about 60,000, manufactured by Nitto Boseki Co., Ltd.) was added and mixed, and the mixture was heated and dried at 120 ° C. for 10 minutes, and then 20 mesh. 20 by sieving with a sieve
A mesh pass product was obtained. This is called a water absorbing agent (1-10).

-Production Example 11- Epomin P-1 was added to 100 parts of the water-absorbent resin particles (a).
000 (polyethyleneimine, weight average molecular weight of about 70,000,
10 parts of a 30% aqueous solution (manufactured by Nippon Shokubai Co., Ltd.) was added and mixed, and the mixture was heated and dried at 120 ° C. for 10 minutes, and then sieved with a 20 mesh sieve to obtain a 20 mesh passed product.
This is called a water absorbing agent (1-11).

-Production Example 12-For 100 parts of the water-absorbent polymer A obtained in Production Example 1,
Polyethyleneimine Polyethyleneglycol block copolymer (ethyleneimine / ethyleneglycol = 50 /
12.5 parts of a 40% aqueous solution having a molar ratio of 50 and a weight average molecular weight of about 80,000) was added and mixed, dried by heating at 120 ° C. for 10 minutes, and sieved with a 20-mesh sieve to give 20
Particles that passed through the mesh were obtained. This is called a water absorbing agent (1-12).

Production Example 13-For 100 parts of the water-absorbent polymer A obtained in Production Example 1,
20 parts of a 30% aqueous solution of Epomin P-1000 (polyethyleneimine, weight average molecular weight of about 70,000, manufactured by Nippon Shokubai Co., Ltd.) was added and mixed, and after heating and drying at 120 ° C. for 10 minutes, it was sieved with a 20 mesh sieve. A 20-mesh pass product was obtained. In addition to this, Aerosil 20
0 (manufactured by Nippon Aerosil Co., Ltd., ultrafine silicon oxide) was added and mixed in an amount of 1.0 part. This is called a water absorbing agent (1-13).

-Comparative Production Example 1- The water absorbent resin particles (a) were used as a comparative water absorbing agent (1-1). -Comparative Production Example 2-The water-absorbent polymer A obtained in Production Example 1 was sieved with a 20-mesh sieve to obtain a 20-mesh pass product. This is referred to as a comparative water absorbing agent (1-2).

-Comparative Production Example 3- 10 parts of a 30% aqueous solution of ethylenediamine was added to and mixed with 100 parts of the water-absorbing polymer A obtained in Production Example 1, and 12
The mixture was heat-treated at 0 ° C. for 10 minutes and sieved with a 20-mesh sieve to obtain a 20-mesh pass product. This is referred to as a comparative water absorbing agent (1-3).

-Comparative Production Example 4- To 100 parts of the water-absorbent polymer A obtained in Production Example 1, 10% of a 30% aqueous solution of Epomine SP-012 (polyethyleneimine, weight average molecular weight about 1200, manufactured by Nippon Shokubai Co., Ltd.) was used. The mixture was added and mixed in parts, heated and dried at 120 ° C. for 10 minutes, and then sieved with a 20-mesh sieve to obtain a 20-mesh passed product. This is referred to as a comparative water absorbing agent (1-4).

-Comparative Production Example 5-N-based on 100 parts of the water-absorbent polymer A obtained in Production Example 1
-100 powders (nonionic acrylamide polymer having a weight average molecular weight of about 17,000,000, manufactured by Mitsui Cyanamid Co., Ltd., 100-mesh pass product) were added and mixed in an amount of 3 parts.
This is called a comparative water absorbing agent (1-5).

Comparative Production Example 6 With respect to 100 parts of the water-absorbing crosslinked polymer (a), 10 parts of water and an epichlorohydrin-ethylenediamine reaction solution (3 parts of epichlorohydrin, 0.49 parts of ethylenediamine, 30 parts of methanol) were mixed by stirring. A comparative water-absorbing agent (1-6) was obtained by adding and mixing a mixed solution consisting of 2 parts of the mixture which had been left to stand for 15 hours at a temperature of 50 ° C. and a weight average molecular weight of 980).

(Example 1-1) 100 parts of the water-absorbing agent (1-1) obtained in Production Example 1 and 100 parts of crushed pulp were dry-mixed in a mixer, and then on a wire screen using a batch type air papermaking machine. Air-machined into a size of 10 cm ×
It was a 20 cm web. The upper and lower surfaces of the obtained web are sandwiched between tissue papers having a basis weight of 0.0013 g / cm ² ,
After that, hot pressing is performed at a temperature of 150 ° C. and a pressure of 2 kg / cm ² for 1 minute to obtain a basis weight of about 0.05 g / cm ² and a density of about 0.17 g / cm ² .
A water absorber (1-1) of this invention having a size of cm ³ was obtained.

(Examples 1-2 to 1-13 and Comparative Example 1)
-1 to 1-6) The water-absorbing agent (1-
2) to (1-13) and the comparative water-absorbing crosslinked polymer particles (1-1) to (1-6) obtained in Comparative Production Examples 1 to 6 were used to absorb water in the same manner as in Example 1-1. Body (1-2) ~ (1
-13) and comparative water absorbents (1-1) to (1-6) were obtained. The water absorbent and the water absorbent were used so that they had the same number.

(Example 1-14) 100 parts of the water-absorbing agent (1-11) obtained in Production Example 11 and 100 parts of crushed pulp were dry-mixed in a mixer, and then on a wire screen using a batch type air papermaking machine. Air papermaking to size 10
The web was cm × 20 cm. The upper and lower surfaces of the obtained web were sandwiched between tissue papers having a basis weight of 0.0013 g / cm ² , and then pressed at room temperature under a pressure of 2 kg / cm ² for 1 minute to obtain a basis weight of about 0.05 g / cm ² , Density about 0.07g / cm ³
Thus, the water absorbent (1-14) of the present invention was obtained.

(Example 1-15) 20 parts of the water absorbing agent (1-3) obtained in Production Example 3 and 180 parts of crushed pulp were dry-mixed in a mixer, and then on a wire screen using a batch type air papermaking machine. Pneumatic papermaking, size 10cm x 2
The web was 0 cm. The upper and lower surfaces of the obtained web are sandwiched between tissue papers having a basis weight of 0.0013 g / cm ² ,
After that, hot pressing is performed at a temperature of 150 ° C. and a pressure of 2 kg / cm ² for 1 minute to obtain a basis weight of about 0.05 g / cm ² and a density of about 0.12 g / cm ² .
A water absorber (1-15) of this invention having a size of cm ³ was obtained.

Comparative Example 1-7 An example except that the comparative water absorbent (1-2) obtained in Comparative Production Example 2 was used in place of the water absorbent (1-3) in Example 1-15. 1-15
Same as above, basis weight about 0.05g / cm ² , density about 0.12
A comparative water absorbent (1-7) having g / cm ³ was obtained. (Example 1-16) Water absorbing agent (1-3) 4 obtained in Production Example 3
0 part and 160 parts of crushed pulp were dry-mixed in a mixer, and then air-paper-formed on a wire screen using a batch-type air-papermaking machine to obtain a web having dimensions of 10 cm × 20 cm. The upper and lower surfaces of the obtained web have a basis weight of 0.0013 g.
/ Cm ² tissue paper, then temperature 1
Hot pressing was performed at 50 ° C. and a pressure of 2 kg / cm ² for 1 minute to obtain a water absorbent body (1-16) of the present invention having a basis weight of about 0.05 g / cm ² and a density of about 0.14 g / cm ³ .

(Example 1-17) To 100 parts of crushed pulp
On the other hand, Epomin P-1000 (weight average molecular weight of about 70,000
0.4% of polyethyleneimine, manufactured by Nippon Shokubai Co., Ltd.
750 parts of the aqueous solution was impregnated and dried by heating at 120 ° C.
And the water-absorbent polymer A1 obtained in Production Example 1
Dry mix 100 parts in a mixer, then batch type air
Air papermaking on a wire screen using a papermaking machine
To obtain a web having a size of 10 cm × 20 cm. Obtained Hue
0.0013g / cm basis weight²The tissue bag
It is clamped with a taper and then pressure is 2 kg / cm at room temperature.²1 minute
Pressed for between, basis weight about 0.05g / cm ², Density about 0.0
7 g / cm³ The water absorbent (1-17) of this invention was obtained.

(Examples 1-18 to 1-34 and Comparative Examples 1-8 to 1-14) The water absorbers obtained in Examples 1-1 to 1-17 and Comparative Examples 1-1 to 1-7 ( 1-1) to (1-
17) and the comparative water absorbers (1-1) to (1-7) were evaluated by the following methods to evaluate the absorption characteristics of the water absorber. The results are shown in Tables 1 and 2. (Absorbed amount under pressure) As shown in FIG. 1, a container 4 equipped with an outside air suction pipe 2 placed on a balance 1 and containing a physiological saline 3 of 0.9% concentration, and a container 4 of this container 4 An apparatus comprising a reverse funnel 6 communicating with a physiological saline storage section through a conduit 5 and a plate (aperture plate) 7 having a liquid supply hole with a diameter of 10 mm fixed to the center of the top of the reverse funnel 6 is used. Then, the water absorbing body 8 is placed on the perforated plate 7, the weight 9 is placed on the water absorbing body 8, and the amount of absorption of the water absorbing body under 30 g / cm ² load after 30 minutes (absorption under pressure) is determined. It was measured. In addition, the water absorbent used had been previously cut into a circle having a diameter of 9 cm.

(Release rate of water-absorbent agent) While stirring 100 cc of physiological saline in a 100 cc beaker (using a 45 mm stirrer and stirring at 100 rpm), a water absorbent cut into 2 cm x 4 cm was charged. After 10 minutes of stirring, the water absorbing body was taken out, the weight of the water absorbing agent dropped into the physiological saline was measured, and the drop rate of the water absorbing agent was determined by the following formula 1. In addition, in the number 1,
The amount of the water absorbing agent corresponds to the total amount of the water absorbing resin and the cationic polymer compound.

[0054]

[Equation 1]

[0055]

[Table 1]

[0056]

[Table 2]

As is clear from Tables 1 and 2, the water absorbing body using the water absorbing agent obtained by the production method of the present invention has an excellent absorption amount under pressure, and the falling rate of the water absorbing agent is remarkably improved. There is. (Production Example 2-1) Synthesis example of water-absorbent crosslinked polymer (2-a) Sodium acrylate 74.98 mol%, acrylic acid 2
39 of an acrylate-based monomer consisting of 5 mol% and 0.02 mol% of trimethylolpropane triacrylate
% Aqueous solution of 4000 parts and 1.0 part of ammonium persulfate and 0.05 part of L-ascorbic acid were polymerized in a nitrogen atmosphere at 30 to 80 ° C. to obtain a gel-like water-containing crosslinked polymer. The obtained water-containing gel polymer was dried with a hot air dryer at 150 ° C., then crushed with a hammer mill and sieved with a 20 mesh wire netting to obtain a 20 mesh passing product (hereinafter referred to as a water-absorbing crosslinked polymer (2-a I said)).

Example 2-1 Water-absorbing crosslinked polymer (2-
To 100 parts of a), 9 parts of a 12% aqueous solution of a polyamide polyamine epichlorohydrin resin (“Kaimen 557H” manufactured by Dick Hercules) was added and mixed to obtain a water absorbing agent (2-1) of the present invention. (Example 2-2) To 100 parts of the water-absorbing crosslinked polymer (2-a), 6 parts of a 15% aqueous solution of a polyamide polyamine epichlorohydrin resin (“Epinoc P130” manufactured by Dick Hercules Co., Ltd.) was added and mixed. A water absorbing agent (2-2) was obtained.

(Example 2-3) Water-absorbing crosslinked polymer (2-
To a), 7 parts of a 15% aqueous solution of polyamide polyamine epichlorohydrin resin (“SUMIREZ RESIN 650” manufactured by Sumitomo Chemical Co., Ltd.) was added and mixed, and the water absorbing agent (2-
3) was obtained. (Example 2-4) To 100 parts of the water-absorbing crosslinked polymer (2-a), 22 parts of a 30% aqueous solution of a polyamide polyamine epichlorohydrin resin (“Epinox P130” manufactured by Dick Hercules Co., Ltd.) was added and mixed, and at 120 ° C. After heat treatment for 5 minutes, the water absorbing agent (2-4) of the present invention was obtained.

Example 2-5 Water-absorbing crosslinked polymer (2-
b) (Nippon Shokubai Chemical Co., Ltd. “Aqualic C
20 parts of a 30% aqueous solution of polyamide polyamine epichlorohydrin resin was added to and mixed with a mixture of 100 parts of "A" 50 mesh passed product) and 10 parts of cellulose powder ("CF-11" manufactured by Whatman). (2-5) was obtained.

Example 2-6 Water-absorbing crosslinked polymer (2-
c) ("Sunwet IM-1000" manufactured by Sanyo Kasei Co., Ltd.)
16 parts of a 30% aqueous solution of polyamide polyamine epichlorohydrin resin (“SUMIREZ RESIN 650” manufactured by Sumitomo Chemical Co., Ltd.) was added and mixed with 100 parts of the water absorbent (2-6) of the present invention.

(Comparative Example 2-1) Water-absorbing crosslinked polymer (2-
a) To 100 parts, 8 parts of 10% aqueous solution of ethylene glycol diglycidyl ether (“Denacol EX810” manufactured by Nagase Kasei Co., Ltd.) was added and mixed, and heat treated at 120 ° C. for 10 minutes to prepare a comparative water absorbing agent (2-1). Got (Comparative Example 2-2) 100 parts of water-absorbing crosslinked polymer (2-a) was stirred and mixed with 10 parts of water and an epichlorohydrin-ethylenediamine reaction solution (3 parts of epichlorohydrin, 0.49 parts of ethylenediamine, 30 parts of methanol). 50 ° C
Comparative water-absorbing agent (2-2) was obtained by adding and mixing a mixed solution consisting of 2 parts of the mixture left to stand for 15 hours at the above temperature). (Example 2-7) Comparison of water absorbing agents Water absorbing agents (2-1) to (2-6) of this invention and comparative water absorbing agents (2-1), (2-2) and comparative water absorbing agent (2-
3) [Water-absorbing crosslinked polymer (2-a)] The water-absorbing properties of each of them were compared by the following method. The results are shown in Table 3. (Water absorption capacity) About 0.2 g of a water absorbing agent is uniformly put in a non-woven tea bag type bag (40 mm x 150 mm), immersed in a large excess of physiological saline (0.9% saline) and left for 30 minutes. After that, drain the tea bag type bag containing the swelling gel,
The weight was measured. The absorption weight of only the tea bag type bag was used as a blank, and the value obtained by subtracting the value obtained by subtracting the blank weight from the weight after water absorption was divided by the weight of the water absorbing agent was taken as the water absorption ratio (g.
/ G). (Amount of suction) 1 g of water absorbent was added to artificial urine (composition: 1.9% urea,
Add to 16 sheets of toilet paper (55 mm x 75 mm) soaked in 20 ml of an aqueous solution containing 0.8% salt, 0.1% calcium chloride and 0.1% magnesium sulfate.
After the liquid was absorbed for 0 minutes, the swollen gel was collected, and its weight was taken as the suction amount (g / g).

[0063]

[Table 3]

Example 2-8 Preparation of Absorber 100 parts of the water-absorbing agent (2-1) of the present invention and 100 parts of crushed pulp are dry-mixed in a mixer, and then a wire screen is prepared using a batch type air papermaking machine. An air papermaking process was performed on the above to obtain a web having dimensions of 10 cm × 20 cm. The upper and lower surfaces of the obtained web are sandwiched between tissue papers having a basis weight of 0.0013 g / cm ² , and then the temperature is 150 ° C and the pressure is 2 kg / cm.
^It was hot-pressed at ² for 1 minute to obtain an absorbent body (2-1) of the present invention having a basis weight of about 0.05 g / cm ² . Similarly, using the water absorbing agents (2-2) to (2-6) of the present invention and the comparative water absorbing agents (2-1) to (2-3), the absorbent body (2
-2) to (2-6) and comparative absorbers (2-1) to (2)
-3) was obtained. (Example 2-9) Evaluation of absorber The obtained absorbers (2-1) to (2-6) and comparative absorbers (2-1) to (2-3) of the present invention were subjected to the above method. It evaluated and evaluated the absorption characteristic of the absorber. The results are shown in Table 4.

[0065]

[Table 4]

As is clear from Table 4, the absorbent body of the present invention has an excellent absorbency under pressure, and the falling rate of the water absorbing agent is remarkably improved.

[0067]

The water absorbent body of the present invention has an excellent effect that the swollen water-absorbent resin particles do not drop out or move. The water absorption body of the present invention remarkably improves the twisting and the like that tend to occur after the liquid absorption in the conventional water absorption body. Therefore, the water absorbent body of the present invention is particularly useful for absorbent articles such as disposable diapers, sanitary napkins, incontinence pads and the like.

According to the manufacturing method of the present invention, such an excellent water absorber can be easily produced. The water-absorbing agent of the present invention has not only the effect of exhibiting excellent water-absorbing properties by itself, but also the excellent effect that, when compounded with cellulose fibers, the swollen water-absorbing agent does not fall off or migrate. Is. And the absorber of this invention,
Since the water absorbing agent does not move or drop off even after absorbing the liquid, it is possible to remarkably improve the wrinkling of the absorbent body, which has been common in the past. Therefore, the water absorbing agent and the absorbent obtained by the present invention are particularly useful for absorbent articles such as disposable diapers, sanitary napkins and incontinence pads.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for measuring an absorption amount of a water absorbent body under pressure.

[Explanation of symbols]

 1 Balance 2 Outside air suction pipe 3 Saline 4 Container 5 Conduit 6 Reverse funnel 7 Opening plate 8 Water absorber 9 Weight

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI technical display location C08L 101/00 LSY 7167-4J (72) Inventor Tadao Shimomura 5-8 Nishimitabicho, Suita City, Osaka Prefecture No. 8 at Central Research Laboratory of Nippon Shokubai Co., Ltd. (72) Tadanori Sano No. 5-8 Nishimitabicho, Suita City, Osaka Pref.

Claims (23)

[Claims] 1. Water-absorbent resin particles having an acidic group on the surface,
A water absorbing body comprising cellulose fibers and a cationic polymer compound having a weight average molecular weight of 2000 or more. 2. The water absorber according to claim 1, which is a mixture of water-absorbent resin particles, cellulose fibers and a cationic polymer compound. 3. A water absorbent comprising a water absorbing agent obtained by treating water absorbent resin particles having an acidic group on the surface with a cationic polymer compound having a weight average molecular weight of 2000 or more, and a cellulose fiber. 4. The water absorbing body according to claim 3, which is a mixture of a water absorbing agent and cellulose fibers. 5. Water-absorbent resin particles, which are cross-linked with a cross-linking agent having a part of the acidic groups on the surface thereof and having two or more functional groups capable of reacting with the acidic groups to form a covalent bond. The water absorbent body according to any one of claims 1 to 4, which is 6. Water-absorbent resin particles 10 to 95% by weight and cellulose fibers 5 to 90% by weight (total 100% by weight of water-absorbent resin particles and cellulose fibers).
The water absorbent body according to any one of 1 to 3. 7. The water absorbing body according to claim 1, wherein the amount of the cationic polymer compound is in the range of 0.1 to 30 parts by weight with respect to 100 parts by weight of the water absorbent resin particles. 8. The cationic polymer compound contains at least one selected from a primary amino group, a secondary amino group, a tertiary amino group and salts thereof, any one of claims 1 to 7. The water absorbent body according to crab. 9. The water absorbing body according to claim 8, wherein the cationic polymer compound is at least one selected from polyethyleneimine, polyamidoamine, polyetheramine, polyvinylamine, polyamidopolyamine epihalohydrin and polyallylamine. 10. The water absorbent body according to claim 1, wherein the cellulose fiber is a wood pulp fiber. 11. A water-absorbing body, wherein water-absorbent resin particles having an acidic group on the surface, cellulose fibers and a cationic polymer compound having a weight average molecular weight of 2000 or more are mixed in a gas phase, and the mixture is formed into a paper in the gas phase. Production method. 12. A water absorbing agent obtained by treating water-absorbent resin particles having an acidic group on the surface with a cationic polymer compound having a weight average molecular weight of 2000 or more, and cellulose fiber are mixed in a gas phase, and the mixture is mixed. A method for producing a water-absorbing material which is produced in the gas phase. 13. Water-absorbent resin particles, which are crosslinked with a crosslinking agent having a part of the acidic groups on the surface thereof and having two or more functional groups capable of reacting with the acidic groups to form a covalent bond. The method for producing a water absorbent body according to claim 11 or 12, which comprises: 14. The method according to claim 11, wherein after the paper is made, the paper is sandwiched between tissue papers and pressed to integrate them.
2. The method for producing a water absorbent body according to 2. 15. The method for producing a water absorbent body according to claim 14, wherein the water absorbent body is heated during pressurization. 16. A water-absorbing agent comprising a water-absorbing crosslinked polymer and a polyamide polyamine epihalohydrin resin. 17. The water absorbing agent according to claim 16, wherein the water-absorbing cross-linked polymer is an acrylate cross-linked polymer. 18. A method for producing a water absorbing agent, which comprises mixing a polyamide polyamine epihalohydrin resin with a water-absorbing cross-linked polymer. 19. The method according to claim 1, wherein the mixing is performed in the presence of water.
8. The method for producing the water absorbing agent according to item 8. 20. An absorber comprising the water absorbing agent according to claim 16 and a cellulose fiber. 21. The absorbent body according to claim 20, wherein the cellulose fiber is a wood pulp fiber. 22. A method for producing an absorbent body, which comprises dry-mixing the water absorbing agent according to claim 16 and cellulose fibers and compressing the resulting mixture. 23. The method for producing an absorbent body according to claim 22, wherein the compression is performed under heating.