JP2002336694A - Aqueous solution absorbing material and sanitary goods - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous solution absorbing material having higher gel strength and absorption capacity than a conventional material and useful as the aqueous solution absorbing material of sanitary goods such as sanitary items and a paper diaper or others and to provide sanitary goods using the absorbing material. SOLUTION: The aqueous solution absorbing material comprises an organic- inorganic composite polyacrylamide hydrogel containing (A) a polymer of an acrylamide compound, (B) a water-swellable clay mineral which is uniformly dispersible in water and (C) water as constituents and including the component (C) in a three-dimensional network comprising the components (A) and (B) and/or a dried body of the hydrogel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a composition comprising (A) a polymer of an acrylamide compound, (B) a water-swellable clay mineral which can be uniformly dispersed in water, and (C) water. An aqueous solution-absorbing material comprising an organic / inorganic composite polyacrylamide-based aqueous gel and / or a dried product thereof, wherein (C) is contained in a three-dimensional network comprising (A) and (B). . The aqueous solution-absorbing material comprising the organic / inorganic composite polyacrylamide-based aqueous gel and / or its dried product according to the present invention has higher gel strength and aqueous solution-absorbing ability than conventional, and is a sanitary article such as a sanitary article or a disposable diaper. Useful as an absorbent material for other aqueous solutions.

[0002]

2. Description of the Related Art In sanitary articles, disposable diapers or other sanitary articles which absorb water-soluble body fluids, water-absorbing resins are often used as constituent materials instead of conventional pulp and water-absorbing paper. As such a water absorbent resin,
For example, a hydrolyzate of starch-acrylonitrile graft polymer (JP-B-49-43395), a hydrolyzate of acrylonitrile copolymer or acrylamide copolymer (JP-B-53-15959),
A crosslinked product of a polyacrylate, a hydrolyzate of a crosslinked product of an acrylamide copolymer, and a neutralized product of a crosslinked isobutylene-maleic anhydride copolymer are known.

[0003] Such a water-absorbing resin is generally obtained by slightly crosslinking a water-soluble resin to make it insoluble in water. Known methods of crosslinking include a method of adding an organic crosslinking agent during the polymerization of a hydrophilic monomer and crosslinking at the same time as the polymerization, and a method of reacting a water-soluble polymer with an organic crosslinking agent to perform intermolecular crosslinking. I have.

[0004] The water-absorbing resins obtained by these cross-linking methods use as little as possible a cross-linking agent in order to enhance the absorption capacity. However, there are drawbacks such as low absorption capacity, and easy deformation and flow under pressure, so-called gel blocks.

Furthermore, water-soluble components coexist inside the water-absorbent resin, which causes a decrease in absorption rate and a decrease in stability of the water-absorbing gel due to elution of the water-soluble components after absorption. On the other hand, when the crosslinking density is increased by increasing the amount of the crosslinking agent used, if the overall crosslinking is performed at a high density, the absorption capacity, which is the basic performance of the water-absorbing resin, is not preferable.

As a method for solving these problems, a method of crosslinking the surface of the powdery water-absorbing polymer particles with a crosslinking agent (JP-B-60-18690, JP-B-61-1986) has heretofore been used.
No. 48521), a method for improving the surface cross-linking method of water-absorbing resin particles (Japanese Patent Publication No. 6-39487, Japanese Patent Publication No. Hei 6-39487).
No. 74331, U.S. Pat. No. 5,314,420), a method of using trimethylolpropane triacrylate as a crosslinking agent (WO 94/20547), and the like are being studied. However, there is a need for the development of absorbent sanitary materials having higher gel strength and absorption capacity, especially for adult sanitary goods which are subjected to a large pressure or a large throughput.

[0007]

The problem to be solved by the present invention is to provide a gel which has a greater gel strength and absorption capacity than conventional, which is useful as a sanitary product such as a sanitary product, a disposable diaper, or other aqueous solution absorbent. An object of the present invention is to provide an aqueous solution absorbing material and a sanitary article using the same.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that organic and organic compounds obtained by polymerizing an acrylamide compound in the presence of water and a water-swellable clay. The present inventors have found that an inorganic composite polyacrylamide-based aqueous gel and / or a dried product thereof can be an excellent aqueous solution-absorbing material that has solved the above problems, and have completed the present invention.

That is, the present invention comprises three components of (A) a polymer of an acrylamide-based compound, (B) a water-swellable clay mineral which can be uniformly dispersed in water, and (C) water, as constituent components. An aqueous solution-absorbing material comprising an organic / inorganic composite polyacrylamide-based aqueous gel in which (C) is contained in a three-dimensional network composed of (A) and (B) and / or a dried product thereof.

The present invention also relates to an organic / inorganic composite polymer obtained by polymerizing (A) an acrylamide compound in the coexistence of (B) a water-swellable clay mineral which can be uniformly dispersed in water and (C) water. An aqueous solution-absorbing material containing an acrylamide-based aqueous gel and / or a dried product thereof as a constituent.

More specifically, the aqueous solution-absorbing material of the present invention has an organic / inorganic composite polyacrylamide-based aqueous gel having a weight ratio of a water-swellable clay mineral / acrylamide-based compound polymer which can be uniformly dispersed in water. An aqueous solution absorbing material of 0.01 to 10 or an aqueous solution absorbing material in which a water-swellable clay mineral capable of being uniformly dispersed in water is particularly a water-swellable smectite, or an organic / inorganic composite polyacrylamide-based aqueous gel at 20 ° C. An aqueous solution absorbing material characterized in that the weight at the time of equilibrium swelling is at least 20 times the weight of the dried body.

The present invention also relates to an organic / inorganic hybrid polyacrylamide-based aqueous gel (having a diameter of 5.5 mm, containing 10 times the weight (weight ratio) of a polymer of an acrylamide-based compound).
(A length of 30 mm), even if it is compressed to a thickness of 1/3 or less in the thickness direction, its shape is not destroyed.
Organic / inorganic hybrid polyacrylamide-based aqueous gel containing water of 0 times (weight ratio) (5.5 mm in diameter, 30 m in length)
m) includes an aqueous solution-absorbing material characterized in that its shape is not destroyed even when it is stretched to a length of twice or more in the length direction.

Further, the present invention relates to an organic / inorganic composite polyacrylamide-based aqueous gel (having a diameter of 5.5 mm, containing 10 times the weight (weight ratio) of a polymer of an acrylamide-based compound).
An aqueous solution-absorbing material characterized in that its shape is not destroyed even if it is bent at an angle of 100 degrees or more at the length center point, and a sanitary article using these aqueous solution-absorbing materials. Including.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention comprises three components, (A) a polymer of an acrylamide compound, (B) a water-swellable clay mineral which can be uniformly dispersed in water, and (C) water. (C) in the three-dimensional network consisting of (A) and (B)
And an aqueous solution-absorbing material comprising an organic / inorganic composite polyacrylamide-based aqueous gel and / or a dried product thereof as a component, and a sanitary article using the same.

Examples of the (A) acrylamide compound used in the present invention include acrylamide, N-methylacrylamide, N-ethylacrylamide, N-cyclopropylacrylamide, N-isopropylacrylamide, methacrylamide, and N-methylmethacryl. Amide, N-cyclopropylmethacrylamide, N-isopropylmethacrylamide, N, N-dimethylacrylamide, N-methyl-N-ethylacrylamide,

N-methyl-N-isopropylacrylamide, N-methyl-Nn-propylacrylamide,
N, N-diethylacrylamide, N- (hydroxymethyl) acrylamide, diacetoneacrylamide, N
-Acryloylpyrrolidin, N-acryloylpiperidin, N-acryloylmethyl homopiperadin, N
-Acryloylmethylpiperazine and the like. These compounds can be used alone or in combination of two or more.

The water-swellable clay mineral (B) which can be uniformly dispersed in water, which is used in the present invention, among the clay minerals, is finely and uniformly dispersible in water and has the property of dissolving or swelling in water. In particular, a layered clay mineral that can be uniformly dispersed in water at a molecular (single layered) or near-molecular level is preferred. For example, water-swellable smectite and water-swellable mica are used. Specifically, water-swellable hectorite containing sodium as an interlayer ion, water-swellable montmorillonite, water-swellable saponite,
And water-swellable synthetic mica.

In the present invention, the water-swellable clay is particularly preferably dissolved in water. Here, dissolution means a state in which there is no large clay mineral aggregate such as a clay mineral precipitate or a cloudy aqueous solution. More preferably 1
Those having a thickness of about 10 to about 10 nanometers (thickness), particularly preferably those having a thickness of about 1 or 2 layers.

The ratio of polyacrylamide and clay mineral contained in the organic / inorganic composite polyacrylamide-based aqueous gel and / or its dried product used in the present invention may be such that the above properties can be achieved. The weight ratio of the clay mineral / polyacrylamide is preferably from 0.01 to 10, more preferably from 0.03 to 3, although it depends on the type of the clay mineral and is not necessarily limited.
2.0, particularly preferably 0.05 to 1.0.

If the weight ratio of clay mineral / polyacrylamide is less than 0.01, the aqueous gel intended for the present invention cannot be formed. If it exceeds 10, the aqueous gel becomes brittle or a large amount of water is used in production. The problem arises.

The organic / inorganic composite polyacrylamide-based aqueous gel used in the present invention comprises (A) a polymer of an acrylamide-based compound, (B) a water-swellable clay mineral which can be uniformly dispersed in water, and (C) water. And (C) in the three-dimensional network consisting of (A) and (B). This organic / inorganic composite polyacrylamide-based aqueous gel is an aqueous gel obtained by radical polymerization of an acrylamide-based compound in the presence of a water-swellable clay finely dispersed in water, and is one or two layers, or 1 to 10 layers. It is presumed that the clay mineral dispersed on the order of nanometers acts as a crosslinking agent for the acrylamide compound, and has a structure in which the acrylamide polymer and the clay mineral are uniformly compounded in a water-swelled state.

The above-mentioned radical polymerization reaction can be carried out by a known method such as the presence of a peroxide and / or ultraviolet irradiation in the absence of molecular oxygen. Further, the polymerization reaction can be accelerated by heating or irradiation with ultraviolet rays. The radical polymerization initiator and the catalyst can be appropriately selected from known and commonly used radical polymerization initiators and catalysts.

Specifically, water-soluble peroxides such as potassium peroxodisulfate and ammonium peroxodisulfate, and water-soluble azo compounds (eg, VA)
-044, V-50, manufactured by Wako Pure Chemical Industries, Ltd.). As the catalyst, N, N, N ', N'-tetramethylethylenediamine, β-dimethylaminopropionitrile and the like are used. The polymerization temperature can be set in the range of 0 ° C. to 100 ° C. according to the type of the polymerization catalyst or the initiator. The polymerization time also varies depending on the catalyst, the initiator and the polymerization temperature, but is generally in the range of several tens of seconds to several hours.

In the radical polymerization reaction, a known polyacrylamide-based aqueous gel can be prepared in the form of fine particles by further coexisting a known surfactant. The aqueous solution-absorbing material of the present invention comprises an organic / inorganic composite polyacrylamide-based aqueous gel obtained by polymerizing an acrylamide-based compound in the presence of water-swellable clay and water and / or a dried product thereof, and an organic crosslinking agent Is not particularly required, but an organic crosslinking agent may be contained together with the above components depending on the use.

The concentration of the organic crosslinking agent contained is not particularly limited and can be selected according to the purpose. As these organic crosslinking agents, conventionally known N, N'-methylenebisacrylamide, N, N'-propylenebisacrylamide, di (acrylamidomethyl) ether, 1,2-diacrylamidoethylene glycol, 1,3- Diacryloylethylene urea, ethylene diacrylate, N, N'-
Examples thereof include bifunctional compounds such as diallyl tartardiamide and N, N'-bisacrylylcystamine, and trifunctional compounds such as triallyl cyanurate and triallyl isocyanurate.

The organic / inorganic composite polyacrylamide-based aqueous gel used in the present invention and / or its dried product have the characteristics that the polymerization yield is high and there is almost no water-soluble component inside the aqueous gel. This is confirmed by the high polymerization yield after washing with water. Such a result is presumed to be due to the fact that the finely dispersed clay layer acts as an effective crosslinking agent in the polymerization of the acrylamide compound in the presence of the water-swellable clay mineral. Such a low content of water-soluble components inside the aqueous gel is effective for improving the safety, stability, dry feeling, etc. of the absorbent material.

In the aqueous solution absorbing material of the present invention, an organic / inorganic composite polyacrylamide-based aqueous gel and / or a dried product thereof are used as constituents. That is, a dried body substantially free of water or an aqueous gel containing water at or below equilibrium swelling is selected and used according to the purpose. It is also possible to use a combination of dried bodies and aqueous gels having different moisture contents.

The organic / inorganic composite polyacrylamide-based aqueous gel and / or its dried product is polymerized to have a shape and size suitable for an aqueous solution-absorbing material used for sanitary products such as sanitary products and disposable diapers, or It is then processed and used. For example, since the absorption rate of water depends on the shape and size of the gel or dried product, it is effective to make the absorption rate as small as possible and as large as possible in order to increase the absorption rate. For example, in the radical polymerization reaction, a known surfactant is further coexisted to prepare a polyacrylamide-based aqueous gel in the form of fine particles on the order of microns.

The organic / inorganic composite polyacrylamide-based aqueous gel used in the present invention and / or its dried product is characterized by a high water absorption relative to the weight of the dried product. In general, the gel strength decreases when the water absorption is increased, but the organic / inorganic composite polyacrylamide-based aqueous gel in the present invention is
Compared to aqueous gels obtained using conventional organic crosslinking agents,
It has high water absorption and high gel strength.

The water absorption of the organic / inorganic composite polyacrylamide-based aqueous gel used in the present invention, when equilibrated and swollen in water at 20 ° C., is usually at least 20 times, more preferably at least 30 times, particularly preferably at least 30 times the dry weight. Absorbs 40 or more times more water or aqueous solution.

Having a high water absorption can prevent liquid leakage when the aqueous solution absorbing material is used, and can reduce the amount of the aqueous solution absorbing material used in sanitary articles, thereby reducing bulk and cost. There is an effect that can be done. In addition, as the physical properties of the aqueous solution absorbing material, those having toughness after absorbing moisture are preferable, for example, compressed or stretched,
Preferably, it is not easily broken when bent. When an aqueous gel having such excellent mechanical properties is used as an aqueous solution absorbing material, gel blocking during absorption is unlikely to occur.

The aqueous solution-absorbing material comprising the organic / inorganic composite polyacrylamide-based aqueous gel and / or its dried product according to the present invention exhibits good mechanical properties even after absorbing water, and is, for example, subject to compression, tensile or bending deformation. Has toughness to withstand. More specifically, an organic / inorganic composite polyacrylamide-based aqueous gel having a diameter of 5.5 mm and a length of 30 mm containing 10 times (weight ratio) water of a polymer of an acrylamide-based compound (polyacrylamide-based component) is used. It has the characteristic that the shape is not destroyed even if it is compressed and deformed to a thickness of 1/3 or less, particularly preferably 1/5 or less in the thickness direction.

Similarly, an organic / inorganic hybrid polyacrylamide compound having a diameter of 5.5 mm and a length of 30 mm containing water in an amount 10 times (by weight) the polymer of the acrylamide compound (polyacrylamide component). The aqueous gel has a characteristic that its shape is not destroyed even if it is stretched and deformed to a length of at least twice in the length direction, particularly preferably to a length of at least four times.

Furthermore, an organic / inorganic hybrid polyacrylamide-based aqueous gel having a diameter of 5.5 mm and a length of 30 mm containing water in an amount 10 times (by weight) the polymer of the acrylamide-based compound (polyacrylamide-based component) is used. It has a feature that the shape is not destroyed even if it is bent and deformed to an angle of 100 degrees or more at the center point of the length, particularly preferably to an angle of 150 degrees or more.

The dried organic / inorganic composite polyacrylamide-based aqueous gel used in the aqueous solution-absorbing material of the present invention is obtained by drying the organic / inorganic composite polyacrylamide-based aqueous gel obtained by polymerization, or optionally before and after drying. It is obtained by processing such as pulverization and classification. Drying can be performed by a known and commonly used drying method, for example, circulating hot air drying, drying under reduced pressure, and the like. In addition, the shape of the dried body or the aqueous gel is also not particularly limited, such as a sphere, a scale, an amorphous powder, a film, and a fiber, and the size is also, for example, in the case of a powder, the average particle size is usually 10 to 10. Those having a size of 1,000 μm are used, but are not particularly limited.

The organic / inorganic composite polyacrylamide-based aqueous gel used for the aqueous solution-absorbing material of the present invention and / or its dried product contains a clay mineral, but since the clay mineral is finely dispersed, the aqueous solution-absorbing material Can be transparent. Therefore, when absorbing a colored aqueous solution or body fluid, the state of absorption can be detected by light transmission or light reflection. Also, when another organic component or inorganic component is previously dispersed in the aqueous gel, there is an advantage that the dispersion state can be clearly understood.

As the aqueous solution-absorbing material of the present invention, an organic / inorganic composite polyacrylamide-based aqueous gel and / or a dried product thereof may be used alone, but if necessary, other water-soluble polymer, hydrophilic polymer, hydrophobic polymer, etc. May be used in combination with a hydrophilic polymer, a surfactant, an inorganic filler and the like.

The organic / inorganic composite polyacrylamide-based aqueous gel and / or its dried product may be granular, flaky, fibrous,
In addition to being processed into an arbitrary shape such as a film, it can be used in combination with other materials (dispersion, lamination, etc.), and if necessary, an anionic activator (eg: alkyl sulfate) or urea.
Denaturing agents such as formamide, antioxidants (eg, 2-mercaptoethanol), water-soluble polymers (eg, polyvinyl alcohol, polyethylene glycol), agarose,
Wetting agents (eg glycerin), bactericides, coloring agents, fragrances,
Components such as a deodorant, an inorganic powder, and an organic fibrous substance can be used by being included in the aqueous gel and the dried body at any stage.

The aqueous solution-absorbing material of the present invention having the above-mentioned characteristics can be effectively used for sanitary articles such as disposable diapers and sanitary articles. Such sanitary articles are preferably used in the form of commercially available sanitary articles in combination with other known materials and components. For example, in a disposable diaper, a porous, highly hydrophobic nonwoven fabric is arranged on the surface in contact with the skin to prevent stuffiness of the skin, and a cotton-like pulp is arranged as a primary absorbent under the nonwoven fabric to improve the absorption speed. Alternatively, the aqueous solution-absorbing material of the present invention is disposed below in the form of a powder or a thin film so as to increase the amount of absorption, and in close contact with the primary absorbent.

In addition, the area around the disposable diaper is prevented from leaking urine by using a contractible rubber or a fixing adhesive tape. In the case of sanitary napkins, the aqueous solution-absorbing material of the present invention is powdered, mixed with pulp, processed into a sheet, laminated with rayon pulp or absorbent paper, and the surface layer is covered with nonwoven fabric or polyethylene laminated paper. With such a structure, the body fluid such as blood can be rapidly absorbed. Further, the aqueous solution absorbing material of the present invention can absorb not only an aqueous solution such as water or a body fluid, but also an organic solvent mixed with or dissolved in water, and is also useful for absorption separation and recovery thereof. .

[0041]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

Examples 1-4 The clay minerals include [Mg
_5.34Li_0.66Si₈O₂₀(OH)₄] Na⁺
_0.66Water-swellable synthetic hectorite having the composition of
(Laponite XLG, manufactured by Nippon Silica Co., Ltd.)
Vacuum-dried at 2 ° C. for 2 hours. As an organic monomer,
In Example 1, N, N-dimethylacrylamide (DMA
A: Wako Pure Chemical Industries, Ltd.)
Implemented Ilmorpholin (ACMO: Kojin Co., Ltd.)
In Example 3, N, N-diethylacrylamide (DEAA:
Wako Pure Chemical Industries, Ltd.)
Using pillacrylamide (IPAA: manufactured by Kojin Co., Ltd.)
Was.

Incidentally, DMAA, ACMO and DEAA were both silica gel columns (manufactured by Merck) with organic monomers 1
It was used after removing the polymerization inhibitor in a volume of 80 ml to 00 ml. IPAA was recrystallized using a mixed solvent of toluene and hexane (1/10 weight ratio) to be purified into colorless needle crystals before use.

As the polymerization initiator, potassium peroxodisulfate (PPS: manufactured by Kanto Chemical Co., Ltd.) was used as a stock solution by quantifying it with a microsyringe. The catalyst is N, N,
N ', N'-tetramethylethylenediamine (TMED
A: Kanto Chemical Co., Ltd.) TMEDA / water = 160μ
It was diluted and used at a rate of 1/20 g. Examples 1 to 4
The water used in any of the above was pure water obtained by distilling ion-exchanged water, and was used after bubbling high-purity nitrogen for at least 3 hours to remove the contained oxygen.

In all examples of the present invention, all operations before and after the polymerization (all operations until the aqueous gel is taken out) were performed in a nitrogen atmosphere or a nitrogen stream from which oxygen was removed. The preparation of the catalyst and the aqueous initiator solution was carried out in a nitrogen atmosphere in which oxygen was cut off in the same manner as in the above operation.

In a two-necked flask whose inside was replaced with nitrogen and placed in a water bath at 20 ° C., pure water 5 from which the dissolved oxygen had been removed was added.
6.88 g and a Teflon (registered trademark) stirrer were put in, and 1.986 g of Laponite XLG was added little by little while stirring so as to prevent air bubbles from entering, thereby preparing a colorless and transparent solution. To this, 5.25 g of DMAA (Example 1:
XLG / DMAA = 0.378 weight ratio) or ACMO
7.5 g (Example 2: XLG / ACMO = 0.265 weight ratio) or 6.75 g of DEAA (Example 3: XLG /
DEAA = 0.294 weight ratio) or IPAA 6.0 g
(Example 4: XLG / IPAA = 0.331 weight ratio) was added and the mixture was stirred until a colorless and transparent solution was obtained.

Next, the flask was cooled in an ice bath, 48 μl of TMEDA which had been separately cooled in an ice bath was added thereto, and the mixture was stirred for 30 seconds. 3.18 g was added with stirring and stirred for 30 seconds to obtain a colorless and transparent solution. After the solution was kept for 1 minute, it was allowed to stand in a warm water bath at 20 ° C. for 8 hours to complete the polymerization. An elastic organic / inorganic composite polyacrylamide-based aqueous gel in which the entire system was gelled (the contents did not move even when the container was placed sideways) was obtained in the flask.

No aggregation due to heterogeneous or opaque clay minerals or polymers was observed in the gel. As for the transparency of the aqueous gel immediately after the polymerization, Examples 1, 2, and 4 were uniformly transparent, and Example 3 was uniformly translucent. Washing the gel
After the obtained gel was weighed and cut into about 5 mm squares, swelling in a large amount of water at 5 ° C and vacuum drying at 80 ° C were repeated twice. Then, it was vacuum-dried at 100 ° C. for 8 hours to obtain a dried aqueous gel, and the yield after purification was determined from the weight of the dried aqueous gel.
The yields after purification in Examples 1 to 4 were all as high as 99% by weight or more.

The obtained dried aqueous gel was pulverized to an average particle diameter of about 300 μm and then equilibrium-swelled in water at 20 ° C.
The weight of the resulting swell-equilibrated aqueous gel is 52 times (Example 1), 41 times (Example 2), 35 times (Example 3), 60 times (Example 4) the corresponding dry weight, It showed high water absorption.

(Examples 5 to 8) DMAA (Example 5),
ACMO (Example 6), DEAA (Example 7), IPA
A (Example 8) is a colorless and transparent aqueous solution containing a clay mineral, an organic monomer, TMEDA, and PPS prepared in the same manner as in Examples 1 to 4 except that 6.0 g of all of A (Example 8) is used. Was placed in a glass tube container with a stopper and polymerized at 20 ° C. for 8 hours in the same manner with blocking oxygen to obtain a uniform and elastic organic / inorganic composite polyacrylamide-based aqueous gel.

The aqueous gel contained water ten times as large as the polyacrylamide component. A rod-shaped aqueous gel having an outer diameter of 5.5 mm was taken out from the glass tube, and the length was 30 mm.
Using a sample cut to 1/3 and 1/5 compression in the thickness direction, 2 and 4 times stretching in the length direction, and 100 and 150 degrees at the center of the length And a test for bending deformation at an angle larger than that. As a result, in each of the samples of Examples 5 to 8, in the above-mentioned test, the shape was not broken, cracks were generated, and no loss occurred, and the samples returned to the original state. In each of the bending deformation tests, even if the deformation was 180 degrees or more, the specimen returned to the original state without breaking or cracking.

(Examples 9 to 14) The amount of clay mineral (Laponite XLG) was 0.396 g (Examples 9 and 10: XLG
/ IPAA = 0.066 weight ratio), 0.792 g (Example 11, 12: XLG / IPAA = 0.132 weight ratio), 3.564 g (Examples 13, 14: XLG / IP)
AA = 0.594 weight ratio), except that
11 and 13 are the same as those of the fourth embodiment.
Polymerization of Nos. 2 and 14 was carried out in the same manner as in Example 8 to prepare an organic / inorganic composite polyacrylamide-based aqueous gel.

In each of Examples 9 to 14, a transparent uniform aqueous gel was obtained at 20 ° C. The weight of the aqueous gel equilibrated and swollen in 20 ° C. water measured in the same manner as in Example 4 was
The corresponding dry weight was 112 times (Example 9), 71 times (Example 11) and 54 times (Example 13). In Examples 10, 12, and 14, in the compression, stretching, and bending deformation tests under the same conditions as in Example 8 using a rod-shaped aqueous gel having a length of 30 mm, any of the samples of Examples 10, 12, and 14 was used. Also, the shape returned to its original state without being destroyed, cracked or chipped. In each of the bending deformation tests, no destruction or cracking occurred even at a deformation of 180 ° or more, and the test piece returned to the original state after the test.

(Comparative Examples 1-4) Without using a clay mineral,
After adding IPAA, an organic crosslinking agent N, N'-methylenebisacrylamide (BIS) (manufactured by Kanto Chemical Co., Ltd.)
The experiment of Comparative Examples 1 and 2 was performed in the same manner as in Example 4 except that 1 mol% (Comparative Examples 1 and 3) and 5 mol% (Comparative Examples 2 and 4) of IPAA were used. The experiments of Comparative Examples 3 and 4 were carried out in the same manner as in Example 8, and both were polymerized at 20 ° C. for 8 hours to obtain an aqueous gel.

In Comparative Examples 1 and 3, a colorless transparent gel was obtained, and in Comparative Examples 2 and 4, a cloudy gel was obtained. Each gel was brittle without toughness. It is considered that the gel became clouded because the crosslink density became non-uniform in the system by increasing the concentration of the crosslinker, resulting in a non-uniform crosslink structure that caused scattering on the visible light scale. The weight of the aqueous gel equilibrated and swollen in 20 ° C. water measured in the same manner as in Example 4 was 15 times (Comparative Example 1) and 8 times (Comparative Example 2) the corresponding dry weight.

In Comparative Examples 3 and 4, a rod-shaped aqueous gel having a length of 30 mm was used in the same manner as in Example 8.
Under the same conditions as described above, compression, stretching, and bending deformation tests were performed. As a result, in each of Comparative Examples 3 and 4, compression deformation in the thickness direction 1/3, stretching deformation in the length direction 2 times, and 1% in the length center point.
Cracks and shapes were all destroyed by the bending deformation of 00 degrees.

(Comparative Examples 5 and 6) Without using a clay mineral,
After adding the DMAA monomer, the organic crosslinking agent N, N'-
Methylene bisacrylamide (BIS) (manufactured by Kanto Chemical Co., Ltd.) was added in the same manner as in Example 5 except that 1 mol% (Comparative Example 5) and 5 mol% (Comparative Example 6) of DMAA or IPAA were added. The experiments of Comparative Examples 5 and 6 were performed, and 2
Polymerization was carried out at 0 ° C. for 8 hours to obtain an aqueous gel. In Comparative Example 5, a colorless and transparent gel was obtained, and in Comparative Example 6, a cloudy gel was obtained. However, each gel was a brittle gel without toughness.

Using a rod-shaped aqueous gel having a length of 30 mm in the same manner as in Example 5, compression, stretching and bending deformation tests were performed under the same test conditions as in Example 5. As a result, in each of Comparative Examples 5 and 6, cracks were caused by compression deformation in the thickness direction of 1/3, extension deformation in the length direction by 2 times, and bending deformation of 100 degrees at the center of the length. Or the shape was destroyed.

[0059]

The absorbent sanitary material comprising the organic / inorganic composite polyacrylamide-based aqueous gel and / or the dried product thereof according to the present invention is superior to the conventional aqueous gel in liquid absorbency in a dried gel product, Further, it is excellent in durability against mechanical deformation such as pressure, tension and bending in a gel state, and is useful as an aqueous solution absorbing material, particularly an aqueous solution absorbing material for sanitary goods.

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Claims (9)

[Claims] 1. A composition comprising (A) a polymer of an acrylamide-based compound, (B) a water-swellable clay mineral which can be uniformly dispersed in water, and (C) water as constituents. An organic / inorganic composite polyacrylamide-based aqueous gel containing (C) in a three-dimensional network consisting of (B) and / or
Alternatively, an aqueous solution-absorbing material whose dried body is a constituent. 2. An organic / inorganic composite polyacrylamide-based aqueous solution obtained by polymerizing (A) an acrylamide-based compound in the presence of (B) a water-swellable clay mineral which can be uniformly dispersed in water and (C) water. An aqueous solution-absorbing material comprising a gel and / or a dried product thereof as a constituent. 3. The weight ratio of (B) a water-swellable clay mineral which can be uniformly dispersed in water / (A) a polymer of an acrylamide-based compound is 0.01 to 10; 2. The aqueous solution absorbing material according to item 1. 4. The aqueous solution-absorbing material according to claim 1, wherein (B) the water-swellable clay mineral capable of being uniformly dispersed in water is a water-swellable smectite. 5. The weight of the organic / inorganic composite polyacrylamide aqueous gel at the time of equilibrium swelling at 20 ° C. is 2% of the weight of the dry body.
The aqueous solution-absorbing material according to any one of claims 1 to 4, wherein the ratio is 0 or more. 6. An organic / inorganic composite polyacrylamide-based aqueous gel (5.5 mm in diameter and 30 in length) containing water (A) in an amount 10 times (by weight) the amount of a polymer of the acrylamide-based compound
mm), the shape is not destroyed even when compressed to a thickness of 1/3 or less in the thickness direction.
The aqueous solution-absorbing material according to any one of Items 1 to 4. 7. An organic / inorganic hybrid polyacrylamide-based aqueous gel (5.5 mm in diameter and 30 in length) containing water (A) 10 times the amount (by weight) of a polymer of an acrylamide-based compound.
The aqueous solution-absorbing material according to any one of claims 1 to 4, wherein the shape is not destroyed even if (mm) is stretched twice or more in the length direction. 8. An organic / inorganic hybrid polyacrylamide-based aqueous gel (5.5 mm in diameter, 30 in length) containing (A) 10 times the amount (by weight) of water of a polymer of an acrylamide-based compound.
The aqueous solution-absorbing material according to any one of claims 1 to 4, wherein the shape of the aqueous solution is not destroyed even when (mm) is bent at an angle of 100 degrees or more at the length center point. 9. A sanitary article using the aqueous solution-absorbing material according to any one of claims 1 to 8.