JP2541694B2 - Absorber and absorbent article - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel thin absorber mainly composed of a water-absorbent polymer and hydrophilic fibers, and an absorbent article using the same.

(Prior Art) Most of the absorbent articles for absorbent articles such as disposable paper diapers and sanitary napkins currently on the market have been changed to composites of hydrophilic fibers such as cotton pulp and paper and water-absorbent polymer. There is. As the function required for these absorbents using a relatively large amount of water-absorbent polymer, the absorption capacity,
Thinness, light weight and shape retention are mentioned, and it is necessary to satisfy all of these.

However, although the absorbers currently used are almost satisfactory in absorption capacity, they are not satisfactory in thinness, light weight and shape retention, and therefore, they are thin and lightweight and have a satisfactory absorption capacity for manufacturers and consumers. It was not possible to make a large leak-free absorbent article.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide a novel absorbent body and absorbent article. Another object of the present invention is to provide an absorber and an absorbent article that are thin and lightweight, have a large absorption capacity, and have little leakage.

The inventors of the present invention have intensively studied an absorber to complete this thin and lightweight absorbent article having a large absorption capacity and little leakage. As a result, the absorption amount under pressure of the absorber, the drop rate of the water-absorbent polymer and the wet swelling. The present invention could be completed by using an absorber whose rate is controlled within a specific range.

(Means for Solving the Problems) These objects are 5 to 500 per 100 parts by weight of a water-absorbent polymer which is a cross-linked polymer of a water-soluble ethylenic monomer containing acrylic acid or acrylic acid as a main component. An absorbent body composed of hydrophilic fibers in the range of parts by weight, the absorption amount under pressure to physiological saline of the absorbent body is in the range of 11 to 25 g / g,
Further, it is achieved by an absorber characterized in that the falling rate of the water-absorbent polymer is 45% or less and the wet swelling rate is 200% or more.

These objects are an absorbent article comprising a liquid-permeable front material, a liquid-impermeable back material, and an absorbent layer sandwiched between them, and part or all of the absorbent layer is the same as in the above item 1.
Absorbent article (second invention)
Also achieved by.

(Function) An important point in the present invention is a thin absorber having an excellent absorption capacity because it is an absorber mainly composed of a water-absorbing polymer,
In addition, the liquid absorbs and diffuses without causing gel blocking, and the water-absorbent polymer does not fall off even after absorbing the liquid.

That is, since the falling rate of the water-absorbent polymer is small, the absorbent body is not destroyed even after absorbing the liquid, and therefore the wicking speed of the absorbent body is reduced even when the liquid is absorbed again for the second or third order. The absorber can quickly absorb urine and menstrual blood without. Therefore, it is possible to obtain an absorbent article with little leakage and a soft feeling. In addition, the absorption amount under pressure of the absorber is important in making an absorbent article because the absorber cannot be made lighter if it is too small or too large, or the absorber breaks and leaks. Is a factor. If the wet swelling rate is too small, liquid absorption and diffusion will be delayed, and leakage will occur, so that it cannot be practically thinned and is not put to practical use. Therefore, it becomes possible to produce a thin and lightweight absorbent article without discomfort for the first time by using an absorbent body having a well-balanced wet swelling rate, absorbed amount under pressure, and falling rate.

Therefore, a further important point of the present invention is that the absorbent is a mixture of the water-absorbing polymer and the synthetic pulp (weight ratio 100: 1 to 30) in the presence of water, and the hydrophilic fiber is the weight of the water-absorbing polymer. ratio
It is mixed in the range of 100: 5 to 500, preferably 100: 10 to 200, and the mixture has a density of 0.1 to 1.0 g / cm ³ , preferably 0.1 to 0.
That is, it was heated and compressed to 5 g / cm ³ .

In order to suppress the falling rate of the water-absorbent polymer, for example, a method of fixing the water-absorbent polymer using various binders, or a method of enclosing the water-absorbent polymer in the fiber matrix has been proposed, in these methods In the obtained absorbent body, there is usually a trade-off relationship between the falling rate of the water-absorbent polymer and the absorption amount under pressure.

Therefore, the above-mentioned physical properties of the currently marketed absorber; the absorption amount of physiological saline under pressure is in the range of 11 to 25 g / g, the dropout rate of the water-absorbent polymer is 45% or less, and the wet swelling rate is 200
There is no one that satisfies all% or more.

As an absorber satisfying all these physical properties, a mixture of a water-absorbing polymer and a synthetic pulp (polymerization ratio 100: 1 to 30) in the presence of water and a hydrophilic fiber have a weight ratio of 100 to the water-absorbing polymer:
The mixture is mixed in the range of 10 to 200, and the mixture has a density of 0.1 to 0.5 g / cm ^3.
It is the one that has been heated and compressed.

The water-absorbing polymer in the present invention may be any one as long as it generally has water-absorbing property, for example, (meth) acrylic acid or a salt thereof as a main component, and a water-soluble ethylene obtained by optionally adding a crosslinking agent. In addition to (crosslinked) polymers of water-soluble unsaturated monomers, crosslinked products of polyethylene oxide, polyvinylpyrrolidone, sulfonated polystyrene and polyvinylpyridine, saponified starch-poly (meth) acrylonitrile graft polymer, starch-poly (meth) ) Acrylic acid (and its salt) graft copolymer (and its crosslinked product), starch-poly (meth) acrylic ester graft copolymer (and its crosslinked product), starch-poly (meth) acrylic ester graft copolymer And the like. Preferably, it is a (crosslinked) polymer of a water-soluble ethylenically unsaturated monomer containing acrylic acid or an acrylic acid salt as a main component, more preferably acrylic acid (salt) crosslinked polymer, Either may be used. In addition, these water-absorbing polymers have 2
You may use 1 or more types. The water-absorbing polymer used is 5 g / g
Or more, preferably 20 to 80 g / g, most preferably 35 to 60 g / g
It is capable of absorbing the physiological saline solution and is substantially dry particles. The water-absorbent polymer usually contains a certain amount of water due to its characteristics, but "substantially dry" as used herein means a state in which the particles cannot stick to each other under a normal atmosphere. The shape of the particles may be spherical, granular, irregular, powdery or fibrous such as foam, and may be a single particle or a granulated product. It may have a crosslinking density gradient in the vicinity. In the case of powder, the particle size is preferably such that the weight average particle size is 10 to 1,000 microns, preferably 100 to 700 microns.

Examples of the hydrophilic fibers used in the present invention include wood pulp fibers such as mechanical pulp, chemical pulp, semi-chemical pulp, and dissolving pulp from wood, artificial cellulose fibers such as rayon and acetate, and the like. In the present invention, these hydrophilic fibers are nylon,
It may partially contain synthetic fibers such as polyester and polyolefin. An example of a preferred hydrophilic fiber is wood pulp fiber. The amount of hydrophilic fiber used is 10
It is in the range of 5 to 500 parts by weight, preferably 10 to 200 parts by weight, per 0 parts by weight.

In the present invention, synthetic pulp may be used in combination with the hydrophilic fiber. The amount used is water-absorbent polymer 10
It is 1 to 30 parts by weight, preferably 5 to 25 parts by weight per 0 parts by weight. The synthetic pulp used in the present invention is a thermoplastic resin formed into a pulp and is known per se.
As the thermoplastic resin, polyolefin, polyester,
Examples of polyacrylonitrile and other hydrophobic thermoplastic resins include polyethylene, polypropylene,
From one or more α-olefins such as ethylene-propylene copolymer, ethylene-1-butene copolymer, propylene-1-butene copolymer, ethylene-4-methyl-1-pentene copolymer The following polyolefins are preferable because their hydrophilicity can be significantly improved. A method for producing synthetic pulp from a thermoplastic resin is disclosed in, for example, Japanese Patent Publication No. 47-
21,898, Japanese Patent Publication No. 47-32,133 and Japanese Patent Publication No. 52-47,049
No. This product is available under trade names such as SWP (manufactured by Mitsui Petrochemical Co., Ltd.) and PULPEX (manufactured by Hercules).

 The absorber of the present invention can be obtained, for example, by the following method.

(1) 100 parts by weight of water-absorbent polymer and synthetic pulp 1 to 30
These are mixed while adding 1 to 40 parts by weight of water to 1 part by weight, and the resulting mixture is dry mixed with 5 to 500 parts by weight of hydrophilic fibers such as pulverized pulp to 100 parts by weight of the water-absorbent polymer. After forming into a web by heating, the density is 0.1 to 0.5 by heat compression.
(2) 100 parts by weight of the water-absorbent polymer was mixed with 1 to 30 parts by weight of synthetic pulp moistened with 1 to 40 parts by weight of water to obtain an absorber of g / cm ³ . The mixture is dry-mixed with 5 to 500 parts by weight of hydrophilic fibers such as crushed pulp with respect to 100 parts by weight of the water-absorbent polymer and molded into a web, and then an absorbent having a density of 0.1 to 0.5 g / cm ³ is formed by heat compression. And the like.

The absorbent obtained in this manner, the amount of physiological saline absorbed under pressure is 11 to 25 g / g, preferably 12 to 20 g / g, and the loss rate of the water-absorbent polymer is 45% or less. ,Preferably
30% or less, and wet swelling rate of 200% or more, preferably 220
It had a physical property of up to 600%.

The absorption amount was changed to 30 by changing the mixing ratio.
Although a substance having g / g or more appears, such a substance is not preferable because the wetting stability / absorption efficiency of the absorbent body is lowered due to the above reason. If the dropout rate of the water-absorbent polymer is more than 45%, it is not preferable because, for example, when used in a disposable diaper, the absorbent body is destroyed when the diaper is worn by the movement of the baby and leaks. When the amount of absorption under pressure is less than 11 g / g, the absorbing ability of the absorber is insufficient, and the absorber cannot be made thin and lightweight, which is not preferable. Considering various points above,
It is most desirable that the absorbent material has physical properties such that the absorption amount under pressure is in the range of 11 to 25 g / g, the loss rate of the water-absorbent polymer is 45% or less, and the wet swelling rate is 200% or more. Can be said.

As a method for applying the absorbent body of the present invention satisfying all the absorbent physical properties to an absorbent article, it may be sandwiched between a liquid-permeable sheet and a liquid-impermeable sheet which are other constituent elements of the absorbent article. Alternatively, as the absorbent layer, cotton-like pulp or a known absorbent and the absorbent of the present invention may be used in combination.

The liquid-impermeable sheet used in the present invention is a sheet of a soft synthetic resin such as polyethylene, polypropylene, vinyl chloride resin, nylon, and vinylon, and the liquid-permeable surface material is, for example, natural fiber. (For example, wood or cotton fiber), synthetic fiber (for example, polyester or polyolefin fiber), or a non-woven fabric or woven fabric made of a combination of natural fiber and synthetic fiber, perforated plastic film, porous foam, reticulated foam, etc. Can be mentioned.

The embodiment of the absorbent body and the absorbent article of the present invention has been described above, but the embodiment is not limited to this description, and the embodiment can be arbitrarily changed within the scope of the gist.

(Examples) Hereinafter, examples will be described. In addition, the following reference example,
"Parts" in Examples and Comparative Examples are "parts by weight" unless otherwise specified.

(Performance test) The obtained absorber was evaluated by the following method.

1. 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 0.9% concentration of physiological saline 3 and physiological saline of the container 4. Conduit 5 in the water storage
The reverse funnel 6 communicating with the reverse funnel 6 is connected to the glass filter 7. The absorber 8 is placed on the filter 7 and the weight 9 is placed on the absorber 8.
Was placed, and after 30 minutes, the absorption amount (g / g) of the absorber under a load of 30 g / cm ² was measured. The absorber used was one that had been previously cut into a circle with a diameter of 5.5 mm.

2. Wet swelling rate When measuring the amount of absorption under pressure, measure the dry height of the absorber under a load of 30 g / cm ² , and set the thickness as x (mm). Next, 30 g of swollen absorbent body after absorption measurement under pressure /
Wet height under cm ² load is measured and its thickness is y (m
m). The value obtained by dividing y by x was taken as the wet swelling rate (%).

3. Drop-off rate of water-absorbent polymer In a 100 cc beaker, cut the absorbent body cut into 2 cm x 4 cm to 100
It was thrown while stirring in a cc physiological saline solution (using a 45 mm stirrer and stirring at 100 rpm). After 10 minutes of stirring, the absorber was taken out, the weight of the water-absorbent polymer dropped into the physiological saline was measured, and the amount of the water-absorbent polymer dropped out was measured by the following formula.

Reference Example 1 Sodium acrylate 74.98 mol%, acrylic acid 25 mol% and trimethylolpropane triacrylate,
37% aqueous solution of 0.02 mol% acrylate monomer
4,000 parts were polymerized with 2.0 parts of sodium persulfate and 0.08 part of 1-ascorbic acid under stirring in a nitrogen atmosphere to obtain a gel-like water-containing polymer finely divided into particles having a particle size of about 5 mm. This gel-like water-containing polymer was dried with a hot air dryer at 150 ° C, crushed with a hammer crusher, and sieved with a 20-mesh wire mesh to give 20
The material passed through the mesh was collected (average particle size: 405 microns).
Next, 0.5 part of glycerin, 2 parts of water and 2 parts of ethyl alcohol were added to 100 parts of the fraction and mixed, and then heat treated at 210 ° C. to obtain a water-absorbing polymer A in which the vicinity of the surface was secondarily crosslinked. . The amount of physiological saline absorbed by this product was 50 g / g.

Reference Example 2 Sodium acrylate 74.95 mol% Acrylic acid 25 mol% and trimethylolpropane triacrylate 0.05
37% aqueous solution of acrylate monomer consisting of mol% 4,00
0 part was polymerized with 2.0 parts of sodium persulfate and 0.08 part of 1-ascorbic acid under stirring in a nitrogen atmosphere to give a particle size of about
A gel-like water-containing polymer finely divided into 5 mm was obtained. The gel-like water-containing polymer was dried with a hot air dryer at 150 ° C., pulverized with a hammer pulverizer, sieved with a 20-mesh wire mesh, and the 20-mesh passing product was collected to obtain a water-absorbing polymer B (average). A particle size of 350 microns) was obtained. The amount of physiological saline absorbed by this product was 46 g / g.

Reference Example 3 100 parts of the water-absorbent polymer B obtained in Reference Example 2 was mixed with 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. to obtain a water-absorbing polymer C in which the vicinity of the surface was secondarily crosslinked. The amount of saline absorption of this product
It was 43 g / g.

Reference Example 4 The water-absorbent polymer C obtained in Reference Example 3 was classified with 6 to 100 mesh to separate the water-absorbent polymer D (particle size 250 to 149 microns). The amount of physiological saline absorbed by this product was 42 g / g.

Example 1 100 parts by weight of water-absorbent polymer A and synthetic pulp (trade name: S
WP “UL-415”: Mitsui Petrochemical Co., Ltd. 25 parts by weight 25
The mixture was mixed while adding parts by weight of water. Then mix 12
5 parts by weight of pulverized pulp was dry-mixed in a mixer, and air-paper was formed on a wire screen by using a batch type air-paper making device to obtain a web having dimensions of 14 cm × 40 cm and basis weight of 0.047 g / cm ² . The obtained web is compressed and heated at 150 ° C for 10 minutes,
An absorber (1) of the present invention having a density of 0.16 g / cm ³ was obtained. The absorbent body (1) thus obtained had an absorption amount under pressure of 16.5 g / g, a loss rate of the water-absorbent polymer was 19%, and a wet swelling rate was 256%.

Example 2 In the same manner as in Example 1, except that the amount of water was changed to 32 parts by weight, the amount of synthetic pulp was changed to 17 parts by weight, and the amount of ground pulp was changed to 133 parts by weight, the basis weight was 0.051 g / cm ² , An absorber (2) of the present invention having a density of 0.13 g / cm ³ was obtained. The absorbent (2) thus obtained had a pressure absorption of 16.0 g / g, a water-absorbent polymer dropout rate of 22%, and a wet swelling rate of 210%.

Example 3 To 100 parts by weight of the water-absorbent polymer A, 7 parts by weight of synthetic pulp moistened with 5 parts by weight of water in advance was added and mixed. The mixture is dry mixed in a mixer with 67 parts by weight of crushed pulp, and air-processed on a wire screen using a batch-type air-papermaking machine, dimensions 14 cm x 40 cm, basis weight 0.042 g / c.
and the web of the m ^2. Compress the resulting web at 150 ° C for 10
Absorbent body (3) of the present invention having a density of 0.20 g / cm ³ by heating for ³ minutes
I got The absorption amount under pressure of the obtained absorbent body (3) is 15.8 g /
g, the falling rate of the water-absorbent polymer was 20%, and the wet swelling rate was 270%.

Example 4 100 parts by weight of water-absorbent polymer C and synthetic pulp (trade name: S
WP “UL-415”: Mitsui Petrochemical Co., Ltd. 13 parts by weight 20 parts
The mixture was mixed while adding parts by weight of water. Then mix 10
Dry mixing was performed with 0 part by weight of crushed pulp in a mixer, and air-making was performed on a wire screen using a batch-type air-making machine to obtain a web having dimensions of 14 cm × 40 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 embossed at 150 ° C. for 1 minute to give a basis weight of 0.054 g / cm ² and a density of 0.27 g / cm ³ of the present invention. Absorbents (4)
I got The absorption amount under pressure of the obtained absorbent body (4) is 14.4 g /
g, the falling rate of the water-absorbent polymer was 6%, and the wet swelling rate was 300%.

Example 5 An absorbent body (5) of the present invention having a basis weight of 0.044 g / cm ² and a density of 0.22 g / cm ³ was obtained in the same manner as in Example 4 except that the amount of crushed pulp was 66 parts by weight. The absorbent body (5) thus obtained had an absorption amount under pressure of 17.3 g / g, a falling rate of the water absorbent polymer was 7%, and a wet swelling rate was 325%.

Example 6 The amount of synthetic pulp was 15 parts by weight, and the amount of ground pulp was 34.
The basis weight is 0.029 g / c in the same manner as in Example 4 except that parts by weight are used.
An absorber (6) of the present invention having m ² and a density of 0.30 g / cm ³ was obtained. The absorbent body (6) thus obtained had an absorption capacity under pressure of 16.3 g / g, a loss rate of the water-absorbent polymer was 19%, and a wet swelling rate was 300%.

Example 7 100 parts by weight of water-absorbent polymer C and synthetic pulp (trade name: S
WP "UL-415": 20 parts by weight of 12 parts by Mitsui Petrochemical Co., Ltd.
The mixture was mixed while adding parts by weight of water. Then mix 13
1 part by weight of pulverized pulp was dry-mixed in a mixer, and air-paper-making was carried out on a wire screen using a batch-type air-making machine to obtain a web having dimensions of 14 cm × 40 cm. The upper and lower surfaces of the resultant web was nipped with a tissue paper having a basis weight of 0.0013 g / cm ^2, and 1 minute embossing press Thereafter 0.99 ° C., basis weight 0.047 g / cm ^2, the present invention a density 0.24 g / cm ³ Absorbents (7)
I got The obtained absorbent body (7) has an absorption amount under pressure of 12.5 g /
g, the falling rate of the water-absorbent polymer was 8%, and the wet swelling rate was 275%.

Example 8 The amount of synthetic pulp was 5 parts by weight, and the amount of ground pulp was 10 parts.
The basis weight is 0.050 g / same as in Example 7 except that 0 part by weight is used.
An absorber (8) of the present invention having a cm ² density of 0.25 g / cm ³ was obtained. The absorbent body (8) obtained had an absorption capacity under pressure of 15.3 g / g, a falling rate of the water absorbent polymer was 13%, and a wet swelling rate was 225%.

Example 9 The amount of synthetic pulp was 23 parts by weight, and the amount of ground pulp was 13 parts.
The basis weight is 0.060 g / same as in Example 7 except that the amount is 3 parts by weight.
An absorber (9) of the present invention having a cm ² density of 0.30 g / cm ³ was obtained. The absorbent body (9) obtained had an absorption amount under pressure of 13.5 g / g, a falling rate of the water absorbent polymer was 12%, and a wet swelling rate was 400%.

Example 10 The amount of synthetic pulp was 24 parts by weight and the amount of ground pulp was 16 parts.
The basis weight is 0.070 g / in the same manner as in Example 7 except that the amount is 7 parts by weight.
An absorbent body (10) of the present invention having a cm ² density of 0.35 g / cm ³ was obtained. The absorbent body (10) obtained had an absorption capacity under pressure of 12.3 g / g, a falling rate of the water-absorbent polymer was 15%, and a wet swelling rate was 400%.

Example 11 An absorbent body (11) of the present invention having a basis weight of 0.044 g / cm ² and a density of 0.33 g / cm ³ was obtained in the same manner as in Example 9 except that the amount of crushed pulp was 67 parts by weight. The absorbent body (11) obtained had an absorption capacity under pressure of 14.2 g / g, and a water-absorbent polymer dropout rate was 10% and a wet swelling rate was 333%.

Example 12 100 parts by weight of water-absorbent polymer D and synthetic pulp (trade name: S
WP "UL-415": Mitsui Petrochemical Co., Ltd. 13 parts by weight was mixed while adding 20 parts by weight of a 30% aqueous solution of polyaluminum chloride. Then, the mixture is dry-mixed with 100 parts by weight of crushed pulp in a mixer, and air-paper-formed on a wire screen using a batch-type air-papermaking device, and the dimensions are 14 cm × 40 cm.
The web of. The top and bottom surfaces of the obtained web are 0.0013
Nip it with tissue paper of g / cm ² and then at 150 ℃ for 1
Embossing press for minutes, basis weight 0.042 g / cm ² , density 0.21 g /
A cm ³ absorbent body (12) of the present invention was obtained. The resulting absorber (1
The absorption amount under pressure of 2) was 13.2 g / g, the falling rate of the water-absorbent polymer was 5%, and the wet swelling rate was 350%.

Example 13 100 parts by weight of water-absorbent polymer B and synthetic pulp (trade name: S
WP “UL-415”: Mitsui Petrochemical Co., Ltd. 13 parts by weight was mixed while adding 20 parts by weight of a 1% by weight aqueous solution of ethylene glycol diglycidyl ether (Nagase Kasei Co., Ltd .: Denacol EX-810). . Then, the mixture is dry mixed in a mixer with 67 parts by weight of crushed pulp, air-making on a wire screen using a batch type air-making machine,
The web was 14 cm × 40 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, emboss press for 1 minute at 150 ℃, basis weight 0.047g /
An absorber (13) of the present invention having a cm ² density of 0.23 g / cm ³ was obtained. The absorbent body (13) obtained had an absorption amount under pressure of 13.7 g / g, a falling rate of the water absorbent polymer was 3%, and a wet swelling rate was 250%.

Example 14 In the same manner as in Example 8 except that the amount of synthetic pulp was changed to 7 parts by weight in Example 8, the basis weight was 0.043 g / cm ² and the density was 0.22.
An absorbent body (14) of the present invention with g / cm ³ was obtained. The absorbent body (14) obtained had an absorption capacity under pressure of 15.3 g / g, a falling rate of the water-absorbent polymer was 14%, and a wet swelling rate was 300%.

Example 15 100 parts by weight of water-absorbent polymer C and synthetic pulp (trade name: S
WP “UL-415”: Mitsui Petrochemical Co., Ltd. 13 parts by weight 20 parts
The mixture was mixed while adding parts by weight of water. Then mix 10
Dry mixing was performed with 0 part by weight of crushed pulp in a mixer, and air-making was performed on a wire screen using a batch-type air-making machine to obtain a web having dimensions of 14 cm × 40 cm. The upper and lower surfaces of the obtained web are sandwiched between tissue papers with a basis weight of 0.002 g / cm ² , and then embossed at 200 ° C for 10 seconds to obtain a basis weight.
An absorber (15) of the present invention having a density of 0.052 g / cm ² and a density of 0.26 g / cm ³ was obtained. The obtained absorbent body (15) has an absorption amount under pressure of 14.5 g /
g, the falling rate of the water-absorbent polymer was 11%, and the wet swelling rate was 300%.

Example 16 100 parts by weight of water-absorbent polymer C and synthetic pulp (trade name: S
WP “UL-415”: 20 parts by weight of 10 parts by Mitsui Petrochemical Co., Ltd.
The mixture was mixed while adding parts by weight of water. Then mix 13
Dry mixing was performed with 3 parts by weight of crushed pulp in a mixer, and air-making was carried out on a wire screen using a batch-type air-making machine to obtain a web having dimensions of 14 cm × 40 cm. The upper and lower surfaces of the obtained web are sandwiched between tissue papers having a basis weight of 0.002 g / cm ² , and then embossed at 150 ° C for 10 minutes to obtain a basis weight.
The absorbent body (16) of the present invention having a density of 0.092 g / cm ² and a density of 0.23 g / cm ³ was obtained. The amount of absorption of the obtained absorbent body (16) under pressure is 13.5 g /
g, the falling rate of the water-absorbent polymer was 29%, and the wet swelling rate was 350%.

Example 17 100 parts by weight of water-absorbent polymer A and 8 parts by weight of synthetic pulp
20 parts by weight of water was added and mixed. The mixture was dry mixed with 70 parts by weight of ground pulp in a mixer and then air-papered onto a wire mesh screen to give a web. Separately, a web composed of 35 parts by weight of crushed pulp and 0.7 parts by weight of synthetic pulp was prepared, and both sides of the web were sandwiched by two pieces of the same to obtain a web having dimensions of 14 cm × 40 cm and basis weight of 0.046 g / cm ² . The obtained web was sandwiched between embossing hot presses and heated at 150 ° C. for 1 minute to obtain an absorber (17) of the present invention having a density of 0.23 g / cm ³ . The absorbent body (17) obtained had an absorption capacity under pressure of 13.5 g / g, a falling rate of the water absorbent polymer was 20%, and a wet swelling rate was 352%.

Example 18 100 parts by weight of water-absorbent polymer D and 20 parts by weight of synthetic pulp
20 parts by weight of water was added and mixed. The mixture was dry mixed with 18 parts by weight of crushed pulp, and then air-formed on a wire mesh screen to obtain a web. This product was sandwiched between tissues with a basis weight of 0.0013 / cm ² and then embossed at 150 ° C for 1 minute to produce a basis weight of 0.019g / cm ² and a density of 0.25g / cm ^3.
An absorbent body (18) of the present invention was obtained. The resulting absorbent body (18)
Absorbency under pressure of 18.0 g / g, the loss rate of the absorbent polymer is 35
%, The wet swelling ratio was 375%.

Example 19 100 parts by weight of water-absorbent polymer A and synthetic pulp (trade name: S
WP “UL-415”: Mitsui Petrochemical Co., Ltd. 13 parts by weight 10
The mixture was mixed while adding parts by weight of water. The mixture is then sandwiched between two webs of 33 parts by weight ground pulp,
A web having dimensions of 14 cm × 40 cm and a basis weight of 0.052 g / cm ^{2 was} prepared. The obtained web was sandwiched between embossing hot presses and heated at 150 ° C. for 1 minute to obtain an absorbent body (19) of the present invention having a density of 0.17 g / cm ³ . The absorption capacity under pressure of the obtained absorbent body (19) is 12.5 g /
g, the falling rate of the water-absorbent polymer was 33%, and the wet swelling rate was 233%.

Example 20 100 parts by weight of water-absorbent polymer C and synthetic pulp (trade name: S
WP "UL-415": 20 parts by weight of 20 parts by Mitsui Petrochemical Co., Ltd.
The mixture was mixed while adding parts by weight of water. Then mix 60
Dry mixing was carried out in a mixer with crushed pulp of 1 part by weight, and air-making was carried out on a wire screen using a batch type air-making machine to obtain a web having dimensions of 14 cm × 40 cm. Then, put a web consisting of 30 parts by weight of crushed pulp on one side of the web,
Furthermore, after sandwiching the upper and lower surfaces of the obtained web with a tissue having a basis weight of 0.0013 g / cm ² , the web is passed between heating rollers and heated at 200 ° C. for 20 seconds to obtain a basis weight of 0.048 g / cm ² and a density of 0.16. g
An absorbent body (20) of the present invention having a density of / cm ³ was obtained. The absorbent body (20) thus obtained had an absorption amount under pressure of 12.2 g / g, a falling rate of the water absorbent polymer was 14%, and a wet swelling rate was 210%.

Comparative Example 1 100 parts by weight of water-absorbent polymer C and synthetic pulp (trade name: S
WP “UL-415”: 20 parts by weight of 33 parts by Mitsui Petrochemical Co., Ltd.
The mixture was mixed while adding parts by weight of water. Then mix 10
Dry mixing was performed with 0 part by weight of crushed pulp in a mixer, and air-making was performed on a wire screen using a batch-type air-making machine to obtain a web having dimensions of 14 cm × 40 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 embossed for 1 minute at 150 ° C to obtain a basis weight.
A comparative absorber (1) having a density of 0.048 g / cm ² and a density of 0.24 g / cm ³ was obtained. Absorption amount under pressure of the obtained comparative absorbent body (1) 10.2 g /
g, the falling rate of the water-absorbent polymer was 17%, and the wet swelling rate was 250%.

Comparative Example 2 100 parts by weight of water-absorbent polymer C and synthetic pulp (trade name: S
WP “UL-415”: 20 parts by 66 parts by weight of Mitsui Petrochemical Co., Ltd.
The mixture was mixed while adding parts by weight of water. Then mix 10
Dry mixing was performed with 0 part by weight of crushed pulp in a mixer, and air-making was performed on a wire screen using a batch-type air-making machine to obtain a web having dimensions of 14 cm × 40 cm. The resulting sandwiched the upper and lower surfaces of the web with a basis weight 0.0013 g / cm ² of tissue paper, and 1 minute embossing press Thereafter 0.99 ° C., basis weight 0.056 g / cm ^2, compared the absorption of density 0.28 g / cm ³ Body (2) was obtained. Absorption amount under pressure of the obtained comparative absorbent body (2) 8.8 g / g,
The water-absorbent polymer had a falling rate of 5% and a wet swelling rate of 275%.

Comparative Example 3 100 parts by weight of water-absorbent polymer C and 100 parts by weight 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, and the dimensions were measured.
A 14 cm x 40 cm web was used. 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 embossed at 150 ° C for 1 minute to obtain a basis weight of 0.043 g / c.
A comparative absorber (3) having m ² and a density of 0.17 g / cm ³ was obtained. The comparative absorbent body (3) obtained had an absorption amount under pressure of 13.8 g / g, a falling rate of the water absorbent polymer was 76%, and a wet swelling rate was 240%.

Comparative Example 4 100 parts by weight of water absorbent polymer C, synthetic pulp (“UL415”) 1
3 parts by weight and 100 parts by weight 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 14 cm × 40 cm. The top and bottom surfaces of the obtained web are 0.0013 g / cm basis weight.
Sandwiched by ^two of the tissue paper, and 1 minute embossing press Thereafter 0.99 ° C., basis weight 0.049 g / cm ^2, density of 0.25 g / cm ³
Comparative absorbent body (4) was obtained. The obtained comparative absorber (4)
Absorbency under pressure of 10.9g / g, the loss rate of the water-absorbent polymer is 53
%, The wet swelling ratio was 250%.

Comparative Example 5 100 parts by weight of water-absorbent polymer C and synthetic pulp (trade name: S
WP “UL-415”: Mitsui Petrochemical Co., Ltd. 13 parts by weight 20 parts
The mixture was mixed while adding parts by weight of water. Then mix 10
Dry mixing was performed with 0 part by weight of crushed pulp in a mixer, and air-making was performed on a wire screen using a batch-type air-making machine to obtain a web having dimensions of 14 cm × 40 cm. The upper and lower surfaces of the obtained web are sandwiched between tissue papers having a basis weight of 13 g / cm ² , and then heated at 150 ° C for 10 minutes to obtain a basis weight of 0.050 g / cm ² ,
A comparative absorber (5) having a density of 0.08 g / cm ³ was obtained. The comparative absorbent body (5) thus obtained had an absorption amount under pressure of 13.9 g / g, a falling water polymer removal rate of 56%, and a wet swelling rate of 100%.

Example 21 Liquid-permeable polypropylene topsheet, two tissues, absorbent body (1) of the present invention (15 g in weight) cut into 9 cm × 35 cm, liquid-impermeable polyethylene backsheet containing leg gathers and two tapes A disposable diaper consisting of a fastener was assembled by hand by fastening the individual components with double-sided tape. The total weight of the diaper is 33
It was g.

The obtained diaper was attached to a one-year-old child (body weight: 10 kg) and compared with a currently marketed diaper (total weight: 50 g). The diaper using the absorbent body of the present invention shows shape retention after urine absorption. Remarkably excellent and less leaky.

Example 22 A disposable diaper using an absorbent body having various properties was prepared in the same manner as in Example 21. These diapers were tested by a panel of 7 mothers for about a month. Each panelist randomly received and tested 30 diapers. After the test, each diaper was collected, and the leakage rate and the shape retention of the absorbent body were compared. The results are shown in Table 1. It can be seen that the absorbent article using the absorbent body of the present invention has excellent absorption characteristics.

(Effects of the invention) Since the absorbent body obtained in the present invention has the above-mentioned constitution, it is used in absorbent articles in the field of medical protection materials such as sanitary napkins, paper diapers, incontinence pads, breast milk pads and medical pads. Best for absorbers. Further, it can be used for various purposes requiring water retention / absorption such as a freshness-retaining material, an agricultural / horticultural water retaining material, and an industrial water absorbing material.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an absorption amount measuring device under pressure used in the present invention.

Continuation of the front page (56) Reference JP-A 63-288258 (JP, A) JP-A 63-122452 (JP, A) JP-A 61-296162 (JP, A) JP-A 2-74254 (JP , A)

Claims (3)

(57) [Claims] 1. A hydrophilic fiber in the range of 5 to 500 parts by weight per 100 parts by weight of a water-absorbent polymer which is a cross-linked polymer of a water-soluble ethylenic monomer containing acrylic acid or an acrylic acid salt as a main component. Which is an absorbent body, wherein the absorption amount of the absorbent body under pressure against physiological saline is in the range of 11 to 25 g / g, and the loss rate of the water-absorbent polymer is 45% or less, and the wet swelling rate. Is 200% or more. 2. 1 to 30 parts by weight per 100 parts by weight of the water-absorbent polymer.
The absorbent body according to claim 1, wherein a part by weight of synthetic pulp is blended. 3. An absorbent article comprising a liquid-permeable front material, a liquid-impermeable back material, and an absorbent layer sandwiched therebetween, wherein part or all of the absorbent layer is claimed. Two
An absorbent article, which is the absorbent body according to 1.