JP2002053762A - Organic and inorganic composite hydrogel and its producing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel organic and inorganic composite hydrogel which is excellent in uniformity, transparence, mechanical properties, water absorption properties and swell and shrink characteristics, its producing method, and a dried product obtained by removing water from the organic and inorganic composite hydrogel. SOLUTION: The organic and inorganic composite hydrogel comprises (A) a water-soluble organic polymer, (B) a water swelling clay mineral which is possible to uniformly disperse in water, and (C) water as three constituting components, and (C) the water being included into a three-dimensional network comprising the components (A) and (B). Its producing method comprises specified requirements and a dried product is obtained by removing the water from the organic and inorganic composite hydrogel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a water-soluble organic polymer, a water-swellable clay mineral which can be uniformly dispersed in water, and water. The present invention relates to an organic / inorganic composite hydrogel in which water is contained in a three-dimensional network of minerals, a dried product thereof, and a method for producing the same.

[0002]

2. Description of the Related Art Gels have properties intermediate between those of liquids and solids.
The solvent is stably incorporated into the medium. In particular, gels using water as a solvent (hereinafter referred to as hydrogels or aqueous gels) are important constituent materials in living organisms, and have been used in the pharmaceutical, medical and food fields such as food and packaging, sanitary products, cosmetics, and agriculture. (Gel Handbook, edited by Yoshihito Nagata and Kanji Kajiwara, NTT Co., Ltd., 1997
Year).

[0003] Hydrogels contain at least two components. That is, a three-dimensional mesh and water bridged in various ways. As a constituent component of the three-dimensional network, any of an organic compound and an inorganic substance can be used. For example, in a hydrogel of an organic compound, an organic polymer or an organic molecule is cross-linked by a covalent bond, a hydrogen bond, an ionic bond, a hydrophobic bond, or forms a three-dimensional network by using a physical entanglement or microcrystal as a cross-linking point. ing.

Specifically, organic molecules forming a three-dimensional network include ovalbumin and serum albumin, which are cross-linked by hydrophobic bonds, and gelatin, agarose, and alkaline-earth metal ions formed by helix formation. Polyacrylic acid and polystyrene sulfonic acid, which form a polymer, two kinds of polymers (polycation and polyanion) complexed by ionic bond, fully saponified polyvinyl alcohol crosslinked by hydrogen bond, etc., heat, radiation, light, Many are known in which cross-links are formed by covalent bonds between organic polymers by irradiating plasma or adding an organic cross-linking agent.

[0005] On the other hand, as the inorganic substance forming a three-dimensional network, a metal oxide prepared by hydrolysis polycondensation of metal alkoxide (so-called sol-gel reaction) and a layered clay mineral having cations between layers are known. Thus, a three-dimensional network is formed by agglomeration of fine particles due to ionic interaction or the like, and a gel comprising an inorganic substance and water is prepared.

Since inorganic hydrogels have low strength and low elongation and are brittle, they are rarely used as a single hydrogel material. On the other hand, organic compounds,
In particular, hydrogels consisting of a three-dimensional network of organic polymers formed by covalent bonds and water are softer because they have better mechanical properties than inorganic hydrogels and have the potential to demonstrate the properties of organic polymers in hydrogels. Applications are being explored in a wide range of industrial fields as materials and functional gel materials.

In order to expand the usefulness of such an organic crosslinked hydrogel, the uniformity, transparency, mechanical properties, mechanical properties, etc. of the gel are further improved, and the absorption (water absorption) properties are further improved. There is a need for the development of new hydrogels that more effectively express the properties of organic polymers in hydrogels.

[0008]

The object of the present invention is to provide a novel organic / inorganic composite hydrogel having excellent uniformity, transparency, mechanical properties, water absorption, and swelling / shrinking properties. It is an object of the present invention to provide a production method and a dried organic / inorganic composite hydrogel obtained by removing water from the hydrogel.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a water-soluble organic polymer, a water-swellable clay mineral which can be uniformly dispersed in water, and water are essential. A novel hydrogel that incorporates water into a three-dimensional network in which organic polymers and clay minerals are compounded at the molecular level as a component of (hereinafter referred to as an organic-inorganic composite hydrogel)
Was obtained, and the present invention was completed.

That is, the present invention provides (A) a water-soluble organic polymer, and (B) a water-swellable clay mineral which can be uniformly dispersed in water.
(C) An organic / inorganic hybrid hydrogel containing three components of water as constituents, and (C) contained in a three-dimensional network composed of (A) and (B).

The present invention also relates to (B) a water-swellable clay mineral /
(A) An organic-inorganic hybrid hydrogel in which the weight ratio of the water-soluble organic polymer is 0.01 to 10 and (C) is contained in a three-dimensional network composed of (A) and (B). . Further, the present invention is the organic / inorganic composite hydrogel, wherein (A) the water-soluble organic polymer is an organic polymer obtained by polymerizing an acrylamide derivative and / or a methacrylamide derivative.

[0012] The present invention also provides a method for preparing the above-mentioned organic / inorganic composite hydrogel, which has a critical temperature (Tc) at which the transparent and / or volume swelling state is reversibly changed to a opaque and / or volume shrinking state at a high temperature side. ) Is an organic-inorganic composite hydrogel characterized by having The present invention, in particular,
The volume ratio of the hydrogel around the critical temperature in water is 10
An organic / inorganic composite hydrogel characterized by the above.

Further, the present invention relates to {C / (A + B)} × 1
The water content defined by 00 is from 600 to 1000% by weight,
A tensile break load of 0.1 N or more, a tensile break elongation of 100% or more, and a tensile elongation of 100% were measured using a hydrogel having an initial sectional area of 0.237 cm ^2.
%, Wherein the water content {Cmax / (A + B)} × 100 at equilibrium swelling in water at 20 ° C. is 2000% by weight or more. Organic-inorganic composite gel,
(A) 10 times the amount (weight ratio) of water-soluble organic polymer (C)
Contains water and has a visible light transmittance of 80% at a thickness of 25 mm
The organic / inorganic composite gel described above is included.

The present invention also includes a dried organic / inorganic composite hydrogel obtained by removing water from the above-mentioned organic / inorganic composite hydrogel.

Furthermore, the present invention provides a homogeneous solution comprising (A ') a monomer of a water-soluble organic polymer (A), (B) a water-swellable clay mineral which can be uniformly dispersed in water, and (C) water. Is prepared,
A method for producing an organic-inorganic composite hydrogel, which comprises polymerizing (A ′) in the presence of (B).

The present invention also relates to (A '), (B) and (C)
A homogeneous solution containing (A ′), (B), (C) water and an organic solvent miscible with water is prepared, further comprising an organic solvent miscible with water; A method for producing an organic / inorganic hydrogel, wherein the polymerization of (A ′) is carried out in the presence of

Further, the present invention relates to these production methods,
(B) a method for producing an organic-inorganic composite hydrogel in which the weight ratio of the water-swellable clay mineral / (A ′) water-soluble organic polymer (A) monomer is 0.01 to 10;
(A ′) A method for producing an organic / inorganic hybrid hydrogel, wherein the monomer of the water-soluble organic polymer (A) contains an acrylamide derivative and / or a methacrylamide derivative.

The present invention also relates to a critical temperature (Tc) at which the resulting organic / inorganic composite hydrogel is transparent and / or swelled at a low temperature and reversibly changes to an opaque and / or volume shrunk at a high temperature. And a method for producing an organic-inorganic composite hydrogel characterized by having
A method for producing an organic-inorganic composite hydrogel, characterized in that the volume ratio of the hydrogel before and after the critical temperature of the inorganic composite hydrogel in water is 10 or more.

Further, the present invention relates to {C / (A + B)} × 10
The water content defined as 0 is 600 to 1000% by weight, and the initial breaking area is measured using a hydrogel having 0.237 cm ² , the tensile breaking load is 0.1N or more, the tensile breaking elongation is 100% or more, And 100% tensile elongation
For producing an organic / inorganic composite hydrogel having a load of 0.01 N or more at 200 ° C., and a water content {Cmax / (A + B)} × 100 at equilibrium swelling in water at 20 ° C. of 2000
% By weight or more.

Further, the present invention provides that (C) water containing 10 times the amount (by weight) of the water-soluble organic polymer and (C) water, and that the visible light transmittance at a thickness of 25 mm is 80% or more. It includes a method for producing a characteristic organic / inorganic composite gel.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The (A) water-soluble organic polymer referred to in the present invention includes not only a water-soluble organic polymer but also an organic polymer capable of swelling in water. The water solubility and water swellability may be achieved under specific polymer concentration, temperature, pressure conditions, or in the presence of other additional components. The water-soluble organic polymer may be a polymer of a single monomer or a copolymer obtained by polymerizing a plurality of types of monomers.

The (A) water-soluble organic polymer used in the present invention preferably has an interaction with (B) a water-swellable clay mineral which can be uniformly dispersed in water, for example, hydrogen bond and ionic bond with (B). And those having a functional group capable of forming a coordination bond, a covalent bond, and the like.

Specific examples of the organic polymer having these functional groups include organic polymers having an amide group, an amino group, a hydroxyl group, a tetramethylammonium group, a silanol group, an epoxy group, and the like. Further, as the water-soluble organic polymer used in the present invention, those having functionality are particularly preferred. For example, the polymer properties (for example, hydrophilicity and hydrophobicity) in an aqueous solution are determined by LCST (lower critical solution temperature,
Organic polymers having the property of changing significantly due to slight temperature changes before and after the lower critical solution temperature).

As specific examples of (A) the water-soluble organic polymer,
Acrylamide, N-substituted acrylamide derivatives, N,
Water-soluble organic polymers obtained by polymerizing one or more selected from N-disubstituted acrylamide derivatives, N-substituted methacrylamide derivatives, and N, N-disubstituted methacrylamide derivatives are exemplified. It is also possible to use the above-mentioned monomer in combination with another organic monomer as long as a uniform organic / inorganic composite hydrogel is formed.

Examples of such water-soluble organic polymers include poly (acrylamide), poly (N-methylacrylamide), poly (N-ethylacrylamide), and poly (N-methylacrylamide).
Cyclopropylacrylamide), poly (N-isopropylacrylamide), poly (methacrylamide), poly (N-methylmethacrylamide), poly (N-cyclopropylmethacrylamide), poly (N-isopropylmethacrylamide),

Poly (N, N-dimethylacrylamide), poly (N, N-dimethylaminopropylacrylamide), poly (N-methyl-N-ethylacrylamide), poly (N-methyl-N-isopropylacrylamide), poly (N-methyl-N-isopropylacrylamide) (N-methyl-NN-propylacrylamide), poly (N, N-diethylacrylamide),
Examples thereof include poly (N-acryloylpyrrolidin), poly (N-acryloylpiperidin), poly (N-acryloylmethylhomopiperadin), and poly (N-acryloylmethylpiperadin).

As the water-soluble organic polymer (A) used in the present invention, in addition to those that dissolve and swell in water, those that dissolve or swell in a mixed solvent of water and an organic solvent miscible with water. May be. As a mixed solvent of water and an organic solvent miscible with water, a mixture of water and one or more organic solvents miscible with water (forming a homogeneous phase) is used. Examples of these organic solvents include polar solvents such as methanol, acetone, methyl ethyl ketone, and tetrahydrofuran. The mixing ratio of water and these organic solvents can be arbitrarily selected as long as the water-swellable clay (B) can be uniformly dispersed.

The (B) water-swellable clay mineral which can be uniformly dispersed in water as referred to in the present invention is a clay mineral which swells in water and can be uniformly dispersed. ) Or a layered clay mineral that can be uniformly dispersed at a level close thereto. For example, water-swellable smectite and water-swellable mica are used, and specifically, water-swellable hectorite containing sodium as an interlayer ion, water-swellable montmorillonite, water-swellable saponite, water-swellable synthetic mica, and the like. No.

In the present invention, the water-swellable clay mineral needs to be finely and uniformly dispersed in an aqueous solution before the monomer of the water-soluble organic polymer is polymerized. Is desirable. 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, it is dispersed with a thickness of about 1 to 10 layers on the nanometer level, and particularly preferably, it is dispersed with a thickness of about 1 or 2 layers.

The water (C), which is a constituent of the present invention, may be water or a mixed solvent of water and an organic solvent miscible with water, wherein the water-swellable clay mineral and the organic monomer are uniformly dispersed. Is used. When a mixed solvent is used, an organic solvent is contained in the gel in addition to water, but for convenience, these are all referred to as a hydrogel.

The organic / inorganic composite hydrogel of the present invention comprises (C) a three-dimensional network of (A) a water-soluble organic polymer and (B) a water-swellable clay mineral which can be uniformly dispersed in water.
A structure in which water is taken in is formed. That is,
(A) and (B) are complexed at the molecular level in water, so that (A) is bridged by (B) or (B)
Is characterized in that a three-dimensional crosslinked product consisting of (A) and (B), which is bridged by (A), contains water.

That is, the organic / inorganic composite hydrogel of the present invention is a hydrogel that can be formed without an organic crosslinking agent, and is an organic polymer obtained by adding an organic crosslinking agent to a conventionally known organic monomer and polymerizing it. It has excellent properties different from a crosslinked hydrogel (hereinafter referred to as an organic crosslinked hydrogel).

The dried organic / inorganic composite hydrogel of the present invention also needs to form such an organic / inorganic composite hydrogel once, and by drying them, the dried organic / inorganic composite hydrogel is obtained. can get.

For example, as shown in Comparative Examples 5 to 8,
When the respective aqueous solutions (A) and (B) are prepared and then simply mixed, the organic / inorganic composite hydrogel of the present invention cannot be obtained even if the components have the same composition as the present invention.

The ratio of (A) the water-soluble organic polymer to the (B) water-swellable clay mineral which can be uniformly dispersed in water in the organic / inorganic composite hydrogel of the present invention is composed of (A) and (B). It is sufficient that an organic / inorganic hydrogel having a three-dimensional network is prepared, and it differs depending on the type of (A) or (B) to be used, and is not necessarily limited. The weight ratio of / A is 0.01 to 10, more preferably 0.03 to 2.0, and particularly preferably 0.1 to 1.0.

When the weight ratio of B / A is less than 0.01, the gel properties of the present invention are often not sufficient, and when it exceeds 10, the obtained hydrogel becomes brittle or a large amount of water is used. This causes a problem in manufacturing. On the other hand, the ratio of (C) water to (A + B) can be arbitrarily set in a wide range from 0 to a very large value depending on the purpose by adjusting the amount of water in the polymerization process or by swelling and drying thereafter.

The maximum amount of water contained in the organic / inorganic composite hydrogel obtained in the present invention, that is, the maximum water absorption (Cmax) at the time of equilibrium swelling is determined by the types and ratios of the components A and B, temperature and pH The organic / inorganic composite hydrogel of the present invention is characterized in that the Cmax is larger than that of a conventional organic crosslinked hydrogel, although it varies depending on the environmental conditions and the like.

In general, as B / A increases, Cmax decreases. The maximum amount of (C) under a certain condition (equilibrium swelling water absorption Cmax) is measured by keeping the organic-inorganic composite hydrogel in an excess of water for a long time under the condition. For example, when an organic-inorganic composite hydrogel synthesized at a certain water content is held in excess water at a temperature of 20 ° C.,
Water is further incorporated into the hydrogel and eventually reaches equilibrium swelling (maximum swelling) at 20 ° C.

Therefore, the time dependence of the swelling of the hydrogel and the water content at the time of equilibrium swelling can be known by taking out the hydrogel immersed in excess water occasionally and measuring the weight. Water content at equilibrium swelling [｛Cmax / (A +
B)｝ × 100] varies depending on the component types and compositions of A and B as described above, and depending on environmental conditions such as temperature, pH, or salt concentration, and for example, from a low value of 100% by weight or less to 100,000% by weight or more. It is possible to change to high values of.

The organic / inorganic composite hydrogel of the present invention is characterized in that Cmax is larger than that of a conventional organic cross-linked hydrogel. When the organic / inorganic composite hydrogel of the present invention is equilibrium-swelled at, for example, 20 ° C., ｛Cmax
/ (A + B)｝ × 100] is usually 2000% by weight or more, more preferably 3000% by weight or more,
Particularly preferably, the content is 4000% by weight or more.

The organic / inorganic composite hydrogel of the present invention also has a feature that the swelling (water absorption) rate is larger than that of a conventional organic crosslinked hydrogel. This is presumed to be due to the fact that the three-dimensional crosslinking between (A) and (B) does not impair the water absorption properties of (A) and is formed uniformly. Further, when (A) has a property of swelling and shrinking due to a temperature change as described below, it has a feature that not only swelling but also shrinking speed is large.

The organic / inorganic composite hydrogel of the present invention comprises:
Critical temperature (Tc) at which it is transparent and / or swollen on the low temperature side and opaque and / or volume shrunk on the high temperature side
And those having a characteristic that the transparency and the volume can be reversibly changed by a temperature change above and below Tc.

Such an organic / inorganic composite hydrogel is
The organic polymer can be prepared using an organic polymer exhibiting LCST (lower critical solution temperature) in an aqueous solution. The Tc of the organic / inorganic composite hydrogel may be the same temperature or change as the LCST of the organic polymer.

The organic / inorganic hybrid hydrogel of the present invention has a higher water absorption, a higher transparency, and a higher volume ratio and higher transparency when expanded and contracted before and after Tc, compared to the conventional organic crosslinked hydrogel. Changes, large swelling and / or shrinking rates, and some or all of the characteristics such as excellent mechanical and mechanical properties.

For example, in the case of an organic cross-linked hydrogel, when the cross-linking agent concentration is increased and the cross-link density is increased, cross-linking becomes non-uniform and transparency may be lost (Comparative Example 4 and
T.Tanaka, Scientific Ameri
can, 244, 110-123, 1981), the organic-inorganic composite hydrogel of the present invention using the same organic polymer does not lose uniformity and shows high transparency.

Specifically, the organic / inorganic composite hydrogel of the present invention contains (A) 10 times (weight ratio) of water-soluble organic polymer (by weight) (C) water-containing organic / inorganic composite having a thickness of 25 mm. 80% light transmittance of visible light in inorganic composite hydrogel
And more preferably 85% or more, particularly preferably 90% or more. Also, a dried product obtained by drying the organic / inorganic composite hydrogel can have transparency because the water-swellable clay mineral is finely dispersed.

In addition, since the organic / inorganic composite hydrogel of the present invention retains a clear transition characteristic at Tc, as shown in FIG. 1, an organic crosslinked hydrogel having a relatively high crosslink density (Comparative Example 4) is obtained at around Tc. While there is almost no change in transparency,
It has higher mechanical properties and reversibly shows a high change in transparency around Tc (Example 1).

Further, regarding the swelling and shrinking of the hydrogel before and after Tc, as shown in FIG. 2, the organic / inorganic composite hydrogel (Example 1) shrinks and shrinks compared to the organic crosslinked hydrogel (Comparative Example 4) It has the characteristic that the volume ratio at the time is high. The volume ratio of the organic / inorganic composite hydrogel of the present invention at the time of swelling and at the time of contraction can be set according to the purpose. In general, the volume ratio of swelling / shrinking is higher than that of an organic crosslinked hydrogel using the same water-soluble organic polymer. The ratio is large, usually 10 or more,
Preferably it is 20 or more, more preferably 30 or more.

The organic / inorganic composite hydrogel of the present invention comprises:
Those having excellent mechanical properties such as strength, elongation, and toughness are included. In particular, it is characterized by including those having excellent mechanical properties, in addition to the above-mentioned properties such as high water absorbency, transparency and transparency change and volume change. Since the mechanical properties of the organic / inorganic composite hydrogel vary depending on the water content of the hydrogel, the mechanical properties and mechanical properties of the organic / inorganic composite hydrogel of the present invention were tested using a hydrogel having a water content within a certain range. It is expressed by the result.

Specifically, {C / (A + B)} × 100 is 600 to 1000, that is, (C) a hydrogel containing 600 to 1000% by weight of water based on the organic and inorganic components (A + B), or (A) water-soluble organic polymer 1
It is represented by the result of a test using a solution containing 0 times (weight ratio) (C) water.

Furthermore, since the organic-inorganic composite hydrogel of the present invention has a large elongation at break and the cross-sectional area changes during the test, the cross-sectional area (initial cross-sectional area) of the hydrogel at the start of the test is 0.237 cm ² (radius). (Corresponding to a circle of 0.275 cm) was used as the test material.

The organic / inorganic composite hydrogel of the present invention has the above water content and initial cross-sectional area, ie, {C / (A + B)}.
A water content defined by × 100 is 600 to 1000% by weight, and a tensile breaking load measured using a hydrogel having an initial cross-sectional area of 0.237 cm ² is 0.1 N or more, preferably 0.5 N or more. Preferably 1N or more, particularly preferably 2N or more are included.

The organic / inorganic composite hydrogel of the present invention has a tensile elongation at break of 100% or more, more preferably 200% or more, and still more preferably 300% or more, as measured using the hydrogel having the above water content and initial cross-sectional area. % Or more, particularly preferably 500% or more, and the load at a tensile elongation of 100% is 0.01 N or more, more preferably 0.05 N or more, and particularly preferably 0.1 N or more. Things included.

On the other hand, the organic crosslinked hydrogels shown in Comparative Example 3, Comparative Example 4, and Comparative Examples 9 to 12 are extremely weak as compared with the organic / inorganic composite hydrogel of the present invention, and can be mounted on the chuck in the tensile test. In most cases, it is brittle and cannot be made.
Even if the device was devised, the physical properties could not be measured due to destruction immediately after the test.

The organic / inorganic hybrid hydrogel of the present invention exhibits good mechanical properties even when absorbing water, and has, for example, toughness that resists compression, tension, or bending deformation. Specifically, (A) 10 to water-soluble organic polymer
An organic / inorganic composite hydrogel having a diameter of 5.5 mm and a length of 30 mm containing twice the amount (weight ratio) of water (C) was added in the thickness direction.
Compression deformed to a thickness of 以下 or less, preferably to a thickness of １ ／ or less, and / or stretched and deformed to a length of 2 times or more, preferably 4 times or more in the length direction. thing,
And / or those whose shape is not destroyed by bending at an angle of 100 degrees or more at the center point of the length, preferably at an angle of 150 degrees or more.

On the other hand, (B) an organic cross-linked gel having the same composition except that an organic cross-linking agent was used instead of the water-swellable clay mineral was obtained by any or all of the above-mentioned deformation operations.
Cracks are generated, destroying the shape or causing defects.

The organic / inorganic composite hydrogel of the present invention needs to have a three-dimensional network composed of an organic polymer and a clay mineral, and can be produced by the following method. After preparing a homogeneous solution containing (A ′) a monomer of the water-soluble organic polymer (A), (B) a water-swellable clay mineral which can be uniformly dispersed in water, and (C) water, coexistence of (B) The polymerization of (A ′) is performed below. As a result, a fine composite of (A) and (B) at the molecular level is achieved, and the organic and
An inorganic composite hydrogel is obtained.

Specifically, a solution having a composition containing (A ′), (B) and (C) as essential components is used, and (A ′) is radically polymerized in the presence of (B) finely dispersed in water. A method for producing an organic-inorganic composite hydrogel, wherein clay minerals uniformly dispersed at a nanometer level of preferably 1 to 10 layers, more preferably about 1 or 2 layers act as a crosslinking agent for (A '). (A) and (B) show a method of polymerizing and forming a three-dimensional network in (C).

The above 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. As the radical polymerization initiator and the catalyst, known and commonly used radical polymerization initiators and catalysts can be appropriately selected and used. Preferably, those having water dispersibility and uniformly contained in the entire system are used.

Specifically, water-soluble peroxides such as potassium peroxodisulfate and ammonium peroxodisulfate, and water-soluble azo compounds such as V
In addition to A-044, V-50, and V-501 (all manufactured by Wako Pure Chemical Industries, Ltd.), a water-soluble radical initiator having a polyethylene oxide chain is exemplified. On the other hand, as the catalyst, tertiary amine compounds N, N, N ′,
N′-tetramethylethylenediamine, β-dimethylaminopropionitrile and the like are preferably used.

The polymerization temperature can be set in the range of 0 ° C. to 100 ° C. according to the type of the polymerization catalyst and the initiator. The polymerization time also varies depending on the polymerization conditions such as the catalyst, initiator, polymerization temperature, and amount (thickness) of the polymerization solution, and can be generally carried out for several tens seconds to several hours. In order to uniformly conduct polymerization in the entire system, for example, (A ′) and a polymerization initiator dissolved in water are added to a mixture obtained by uniformly mixing (B) and water in advance to prepare a uniform solution. It is effective to take measures such as taking a method of adding a polymerization catalyst dissolved in water.

In the above radical polymerization reaction, it is also possible to coexist a known surfactant to produce the resulting organic / inorganic composite hydrogel in the form of fine particles. In the polymerization of the organic / inorganic composite hydrogel of the present invention, the polymerization yield of (A ′) is high, and the water-soluble organic polymer obtained by polymerization is incorporated into the hydrogel together with the clay mineral and elutes as a water-soluble component. The amount is small. This is confirmed by the high polymerization yield after water washing. These results are presumed to be due to the effect of the finely dispersed clay layer acting as an effective crosslinking agent for the water-soluble organic polymer in the polymerization of (A ′) in the presence of (B).

Further, in the present invention, for the purpose of improving the characteristics of the organic / inorganic composite hydrogel, an organic crosslinking agent may be contained in the aqueous solution together with the essential components (A ′) and (B), if necessary. good. The concentration of the organic crosslinking agent contained is not particularly limited, and can be selected according to the purpose. Organic crosslinking agents that can be included as needed include N, N′-methylenebisacrylamide, N, N′-propylenebisacrylamide, di (acrylamidomethyl) ether, 1,2-di Bifunctional compounds such as acrylamide ethylene glycol, 1,3-diacryloylethylene urea, ethylene diacrylate, N, N′-diallyl tartardiamide, N, N′-bisacrylylcystamine, triallyl cyanurate, Trifunctional compounds such as triallyl isocyanurate are exemplified.

In the production of the organic / inorganic composite hydrogel of the present invention, hydrogels having various shapes can be prepared by changing the shape of the container. For example, an organic / inorganic composite hydrogel having an arbitrary shape such as a fiber shape, a rod shape, a flat plate shape, a columnar shape, a spiral shape, and a spherical shape can be prepared.

The organic / inorganic composite hydrogel and the dried product thereof according to the present invention may contain, if necessary, other than (A), (B) and (C), for example, anionic activators, organic dyes and organic pigments. An organic molecule such as an organic molecule, a water-soluble polymer or a fibrous substance that does not dissolve in water, carbon, an inorganic fine particle component such as silica or titania, and the like can be contained at any stage of production. Further, it can be combined with other materials (dispersion, lamination, etc.) according to the purpose.

The present invention includes a dried organic / inorganic composite hydrogel obtained by removing water from the organic / inorganic composite hydrogel of the present invention. The method for removing water is not particularly limited, but can be performed by appropriately changing conditions such as temperature, air flow, and reduced pressure. Specifically, a hot air circulation dryer, a reduced pressure dryer, or the like is used. The amount of water removed from the hydrogel is also not particularly limited, and can be arbitrarily prepared from those from which water is completely removed to those from which water is left as necessary.

Although the dried organic-inorganic composite hydrogel of the present invention contains a clay mineral, it can be transparent because the clay mineral is finely dispersed. Therefore,
When a colored aqueous solution or the like is absorbed in a hydrogel or a dried product thereof, it is characterized in that the state of absorption can be detected by light transmission or light reflection. Also, when another organic component or inorganic component is dispersed in the hydrogel in advance, there is an advantage that the dispersion state can be clearly understood.

The organic / inorganic composite hydrogel can be pulverized, classified, shaped, etc. from the hydrogel or during the drying or as a dried gel, and can be in a form suitable for transportation, processing and intended use. Specifically, it is in the form of a sphere, scale, powder, film, fiber, pellet, or the like. Regarding the size, for example, in the case of powder, those having an average particle size of usually 10 to 1000 μm are used,
There is no particular limitation.

The dried organic / inorganic composite hydrogel is composed of water,
It can be reversibly returned to the hydrogel again by contact with water such as aqueous solution and humidity. The novel organic compounds of the present invention
The inorganic composite hydrogel and its dried product are useful in a wide range of fields such as daily necessities, medicine / medical care, agriculture, civil engineering, and industrial fields.

[0070]

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.

(Example 1) As a clay mineral, [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 before use. The organic monomer is N-
Isopropylacrylamide (IPAA: Kojin Co., Ltd.)
Manufactured by Toshiba) in a mixed solvent of toluene and hexane (1/10 weight
Ratio) and purified to colorless needle crystals before use
Was.

As the polymerization initiator, potassium peroxodisulfate (PPS: manufactured by Kanto Chemical Co., Ltd.) was prepared by adding PPS / water = 0.3
It was diluted with pure water at a ratio of 84/20 (g / g) and used as an aqueous solution. As the catalyst, N, N, N ', N'-tetramethylethylenediamine (TMEDA: manufactured by Kanto Chemical Co., Ltd.) was diluted at a ratio of TMEDA / water = 160 μl / 20 g and used. As the water, pure water obtained by distilling ion-exchanged water was used. All water was used after bubbling high purity nitrogen for at least 3 hours to remove the contained oxygen.

In a constant temperature chamber at 20 ° C., a flat-bottomed glass container having an inner diameter of 25 mm and a length of 80 mm whose inside was replaced with nitrogen was placed
16.96 g of pure water and a Teflon (registered trademark) stirrer were put therein, and 0.662 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, 2.0 g of IPAA was added and stirred for 5 minutes to obtain a colorless and transparent solution. Next, an aqueous solution of PPS 1.0
6 g and 2.0 g of TMEDA aqueous solution were added with stirring, and
The mixture was further stirred for about 2 seconds to obtain (D) a colorless transparent solution. (D)
A portion (3 ml × 3) was transferred to three glass tube containers having a closed bottom with an inner diameter of 5.5 mm and a length of 150 mm so as not to be exposed to oxygen. The polymerization was carried out by standing still.

The remaining solution (D) was also placed in a flat-bottomed glass container.
The mixture was allowed to stand at 0 ° C. for 15 hours to carry out polymerization. The operations from the preparation of the solution to the polymerization were all performed in a nitrogen atmosphere in which oxygen was cut off. After 15 hours, elastic, tough, colorless, transparent and uniform columnar and rod-like gels were formed in the flat bottom glass container and the glass tube container, and were carefully removed from both containers.

No uneven or opaque aggregation due to clay minerals or the like was observed in the gel. The gel was dried to a constant weight with a vacuum dryer at 100 ° C., and it was found that the hydrogel contained {C / (A + B)} × 100 = 750% by weight of water. The following purification operation was repeated three times on the removed hydrogel to obtain a purified hydrogel.

The purification is carried out by immersing in 2 L of water for 2 days and then immersing in 1 L of water at 70 ° C. for 2 hours and removing.
Was repeated. The purified hydrogel was dried at 100 ° C. under reduced pressure to obtain a dried hydrogel from which water was removed. It was confirmed that when the dried gel was immersed in water at 20 ° C., it returned to an elastic hydrogel having the same shape as before drying.

The dried gel was measured for Fourier transform infrared absorption spectrum (FT-IR) by the KBr method (Fourier transform infrared spectrophotometer FT / IR manufactured by JASCO Corporation).
-550), infrared absorption specific to poly (N-isopropylacrylamide) (eg, 1460 cm ⁻¹ , 1
550 cm ⁻¹ , 1650 cm ⁻¹ , 2920 cm ⁻¹ , 29
70cm ^-1) and Laponite XLG inherent infrared absorption (e.g. 460cm ^-1, 650cm ^-1, 1005c
m ^-1 ) was observed.

Thermogravimetric analysis of the dried gel (TG-DTA220, manufactured by Seiko Instruments Inc .:
The temperature was raised to 600 ° C. at a rate of 10 ° C./min), and B / A = 0.
333 (weight ratio) was obtained.

As described above, the gel obtained in the present example is a hydrogel comprising an organic polymer (poly (N-isopropylacrylamide)), a clay mineral and water, having a component ratio according to the charged composition. A colorless, transparent, and uniform hydrogel can be obtained without adding a cross-linking agent in the synthesis of an organic polymer. By immersing a dried gel (solid) obtained by removing water from the hydrogel into water It was concluded that a three-dimensional network in which the organic polymer and the clay mineral were complexed at the molecular level was formed in water from the fact that the hydrogel returned to the original shape again. In addition,
The organic polymer synthesized under the same conditions except that no clay mineral coexisted became an aqueous polymer solution and did not become a hydrogel.

An unpurified rod-shaped organic / inorganic composite hydrogel (cross-sectional area = 0.237 cm ² ) was tested without any slippage at the chuck portion (Table top universal testing machine AGS-, manufactured by Shimadzu Corporation). H), and a tensile test was performed at a distance between scores of 20 mm and a tensile speed of 100 mm / min. As a result, the breaking load was 1.1 N, the breaking elongation was 550%, and the load at 100% tensile elongation was 0. 09
N.

After purifying a rod-shaped organic / inorganic composite hydrogel cut to a length of 10 mm, the rod was immersed in water at six temperatures ranging from 20 ° C. to 50 ° C., allowed to stand for one day, and its volume was measured. Changes in swelling and shrinking with temperature were measured. FIG. 1 shows the results together with the results of Comparative Example 4 (organic crosslinked hydrogel).

The organic / inorganic composite hydrogel obtained in this example has the above toughness and the critical temperature (T
c), swelling at a temperature below Tc, and shrinking at a temperature below Tc. The volume ratio between swelling and shrinking at 20 ° C. and 50 ° C. showed a high value of 24.

After purifying the columnar organic-inorganic composite hydrogel taken out of the flat bottom glass container, the temperature was 20 ° C. to 50 ° C.
What was immersed in water at the temperature of 5 points was cut out at a thickness of 2 mm, and the light transmittance was measured using NDH-300A manufactured by Nippon Denshoku Industries Co., Ltd. The results are shown in FIG. 2 together with the results of Comparative Example 4. The organic / inorganic composite hydrogel obtained in this example shows a clear change in transparency at the boundary of Tc.
The film became highly transparent at a temperature of c or lower and became opaque (cloudy) at a temperature of Tc or lower.

Examples 2 to 4 Clay mineral (Laponite X)
LG) in an amount of 0.132 g (Example 2), 0.264 g
(Example 3) Polymerization was carried out in the same manner as in Example 1 except that the amount was changed to 1.322 g (Example 4) to prepare an organic / inorganic composite hydrogel. In Examples 2 to 4, colorless and transparent uniform hydrogels were obtained at room temperature.

The results of the hydrogel evaluation measured in the same manner as in Example 1 are shown below. {C / (A + B)} × 100 is 940% by weight (Example 2), 880% by weight (Example 3), 600% by weight (Example 4), and the B / A ratio is 0.1%.
065 (Example 2), 0.135 (Example 3), 0.6
6 (Example 4).

When the temperature of the obtained hydrogel was increased, all of them had a critical temperature (Tc) around 35 ° C.
When the temperature was equal to or less than c, the film was colorless and transparent. The volume ratio between the times of swelling and shrinking in water at 20 ° C. and 50 ° C. was 31 (Example 2) and 13 (Example 4). The shrinkage occurred in a short time within 1 minute due to the temperature change, and the swelling occurred in a shorter time than in Comparative Example 3.

The results of the tensile test were as follows: breaking load was 0.65 N (Example 3), 7.0 N (Example 4), breaking elongation was 430% (Example 3), 650% (Example 4). The load at an elongation of 100% was 0.033 N (Example 3) and 0.40 N (Example 4). Further, after cutting the obtained hydrogel into 5 mm squares, the water content of the hydrogel which was equilibrium-swelled in water at 20 ° C. ΔCmax /
(A + B)｝ × 100 is 11300% by weight (Example 2), 7200% by weight (Example 3), 5000% by weight
(Example 4).

(Examples 5 to 7) As the organic monomer, the IPAA described above was used in Example 5, N, N-dimethylacrylamide (DMAA: Wako Pure Chemical Industries, Ltd.) was used in Example 6, and NAA was used in Example 7. , N-diethylacrylamide (DEAA: Wako Pure Chemical Industries, Ltd.) was used. In addition,
DMAA and DEAA were used after removing the polymerization inhibitor using a silica gel column (manufactured by Merck) at a volume of 80 ml per 100 ml of organic monomer.

In a constant temperature chamber at 20 ° C., a flat-bottomed glass container having an inner diameter of 25 mm and a length of 80 mm whose inside was replaced with nitrogen was placed
18.96 g of pure water and a stirrer made of Teflon were added, and 0.662 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. 2.0 g of IPAA (Example 5) or D
2.0 g of MAA (Example 6) or 2.0 g of DEAA
(Example 7) was added and the mixture was stirred until a colorless and transparent solution was obtained.

To this, 160 μl of TMEDA was added, followed by stirring with 1.06 g of an aqueous PPS solution, followed by stirring for 5 minutes to obtain a colorless and transparent solution (D ′). (D ′) The stirrer was removed from the solution, the solution was sealed, and the solution was allowed to stand at 20 ° C. to gel the entire system (the contents did not move even when the container was placed horizontally). All of the above operations were performed in a nitrogen atmosphere in which oxygen was cut off. Then, while maintaining the N ₂ atmosphere, 70 ℃
And left standing for 2 hours in a water bath to polymerize. After 2 hours, the columnar gel formed in the flat bottom glass container was carefully removed from the container.

In Examples 5 and 7, a uniform opaque gel having elasticity and toughness was obtained. In Example 6, a transparent gel having elasticity and toughness was obtained. No heterogeneous or opaque aggregation due to clay minerals or the like was observed in the cloudy gel.

ΔC / (A) measured in the same manner as in Example 1.
+ B) Δ × 100 was 750% by weight in all cases, and B / A was 0.33 in all cases, indicating that the organic / inorganic composite hydrogel was composed of an organic polymer, a clay mineral, and water. The cloudy hydrogels of Example 5 and Example 7 did not change to transparent even when the temperature was lowered. In addition, the transparent hydrogel of Example 6 remained transparent without becoming cloudy even when the temperature was changed from 0 to 70 ° C.

Examples 8 to 12 As organic monomers,
In Example 8, the N-isopropylacrylamide (IPAA) was used. In Example 9, the N, N-dimethylacrylamide (DMAA) was used. In Example 10, the N, N-diethylacrylamide (DEAA) was used. In Example 11, acryloylmorpholine (ACMO; manufactured by Kojin Co., Ltd.) was used, and in Example 12, N, N-dimethylaminopropylacrylamide (DMAPA; manufactured by Kojin Co., Ltd.) was used.

Note that IPAA (Embodiment 8)
0.75 times (weight ratio) of toluene was added, the mixture was dissolved at 40 ° C., and after returning to room temperature, 7.5 times (weight ratio) of hexane was added and stirred well to obtain needle-like colorless crystals. . Finally, IPAA obtained by removing the solvent by filtration and vacuum drying at room temperature
It was used. DMAA (Example 9), DEAA (Example 10) and ACMO (Example 11) were used in the same manner as in Examples 6 and 7 except that the polymerization inhibitor was removed.

For DMAPA (Example 12), acetone was added by 20% by volume of DMAPA to lower the viscosity, then the polymerization inhibitor was removed with an activated alumina column (80 cc / 100 ml monomer), and then the acetone was removed with a rotary evaporator. Used.

All the water used was pure water obtained by distilling ion-exchanged water, and high-purity nitrogen gas was bubbled therein for at least 3 hours to remove the contained oxygen. In this example, all operations before polymerization (all operations from solution preparation to removal of the hydrogel) were performed in a nitrogen atmosphere or a nitrogen stream from which oxygen was removed. The preparation of the catalyst and the aqueous solution of the initiator was also performed in a nitrogen atmosphere in which oxygen was cut off in the same manner as 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 8 from which the dissolved oxygen had been removed was added.
Put 5.3 g and a Teflon stirrer, and stir 2.9
8 g of Laponite XLG was added little by little while taking care not to introduce air bubbles, to prepare a colorless and transparent solution. This was added to 9.0 g of IPAA (Example 8) or 9.0 A of DMAA.
g (Example 9) or 9.0 g of DEAA (Example 1)
0), or 9.0 g of ACMO (Example 11), or DM
9.0 g of APA (Example 12) was added, and the mixture was stirred until a uniform transparent solution was obtained.

The weight ratio of XLG / monomer was 0.1.
331. Then, the flask was cooled in an ice bath, and TMEDA 72 μm, which had been separately cooled in an ice bath, was used.
1 and stirred for 30 seconds, and then similarly separately,
3. The same PPS aqueous solution as in Example 1 which was cooled in an ice bath.
77 g was added with stirring, and the mixture was stirred for 30 seconds to obtain a uniform transparent solution. The solution was left standing in a 15 ° C. water bath for 20 hours to complete the polymerization.

In each of Examples 8 to 12, an elastic hydrogel 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 heterogeneous or opaque aggregation of clay minerals or polymers was found in the hydrogel. The transparency of the hydrogel obtained by polymerization is determined by the ice bath temperature (about 1 ° C).
As a result, Examples 8, 9, 11, and 12 were uniformly transparent, and Example 10 was uniformly translucent.

The transmittance of visible light of the hydrogel cut to a thickness of 25 mm was measured using NDH-3 manufactured by Nippon Denshoku Industries Co., Ltd.
As a result of measurement using 00A, the total transmittance was 95% (Example 8), 81% (Example 9), 40% (Example 10),
It was 85% (Example 11) and 90% (Example 12).

Next, the ice bath was changed to a warm water bath at 50 ° C., and the change in transparency was examined. In Examples 9, 11 and 12, the transparency was hardly changed, but in Examples 8 and 10, the total transmittance was changed to opaque with a total transmittance of 10% or less.

On the other hand, a hydrogel obtained by polymerization was cut into a rod shape having a diameter of 5.5 mm and a length of 30 mm, and was compressed to 1/3 and 1/5 in the thickness direction. Test to stretch to 4 times and 10 at center of length
A test for bending deformation at 0, 150 and more angles was performed. As a result, in each of the samples of Examples 9 to 12, in the above-mentioned test, the shape was not broken, cracks occurred, or defects did not occur, and the samples returned to the original state.

Further, in the bending deformation test, even in the case of a deformation of 180 ° or more, none of them was broken or cracked, and returned to the original state after the test. Further, the obtained hydrogel was 5.5 mm in diameter (0.237 cm ^{2 in} cross-sectional area) and 50 in length.
mm, the upper and lower 10 mm are not damaged and are sandwiched between round sandpapers so as not to slip, and using the same tensile test apparatus as in Example 1, at a distance between gauge points = 30 mm and a pulling speed = 100 mm / min. A tensile test was performed.

As a result, in Example 8, the breaking load was 2.9.
N, the breaking elongation was 1001%, and the load at 100% tensile elongation was 0.103N. In Example 9, the breaking load was 2.4N, the breaking elongation was 1112%, and the tensile elongation was 100%.
%, The breaking load was 4.8 N, the breaking elongation was 892%, and the tensile elongation was 1 in Example 10.
The load at 00% was 0.173N.

The water content {Cmax / (A + B)} × 100 contained in the hydrogel obtained by cutting the obtained hydrogel into 5 mm square and swelling equilibrium in water at 20 ° C. is 62.
00% by weight (Example 8), 5000% by weight (Example 9), 3700% by weight (Example 10), 4700% by weight
(Example 11). The weight of the dried product obtained by purification in the same manner as in Example 1 was measured, and the polymerization yield of the monomer was 99% or more in all of Examples 8 to 11,
High yields were shown.

(Example 13) Acrylamide (AA) purified using ethanol and toluene as organic monomers
M: manufactured by Kanto Chemical Co., Ltd.) 3.15 g, water-swellable clay mineral XLG 2.8 g (XLG /
Monomer = 0.89 weight ratio), using a total of 50 g as water, and using potassium peroxodisulfate as an initiator in 0.1 g.
A polymerization experiment and an evaluation test were performed in the same manner as in Example 8, except that 05 g was used, N, N'-methylenebisacrylamide was used as a catalyst, and 40 μl of the polymerization temperature was set to 23 ° C.

As a result, a transparent (organic / inorganic) composite hydrogel having a transparency (total transmittance) at a measurement temperature of 1 ° C. and a toughness of 85% at a thickness of 25 mm and having a toughness was obtained. Even when the temperature for measuring the transparency was set to 50 ° C., the total transmittance hardly changed.

(Example 14) 1.788 g of XLG was used as a clay mineral, and an organic crosslinking agent (N, N'-methylenebisacrylamide: BIS: manufactured by Kanto Chemical Co., Ltd.) was used in combination with 0.5% of organic monomer Preparation of a polymerization solution, polymerization experiment and evaluation test were carried out in the same manner as in Example 9 except that mol% was used and the polymerization temperature was 30 ° C.

As a result, a transparent and tough organic-inorganic composite hydrogel gel was obtained. The total transmittance at a thickness of 25 mm (measuring temperature 1 ° C.) was 90%, and the transparency was hardly changed even when the measuring temperature was 50 ° C. A rod-shaped hydrogel cut to 5.5 mm in diameter and 30 mm in length was subjected to a compression deformation test up to 1/5 in the thickness direction, and to a length of 4 mm.
In each of the double stretching deformation test and the bending deformation test up to 180 degrees at the center of the length, the shape was not broken and returned to the original shape after the test.

(Examples 15 to 17) A mixed solvent of water and methanol was used instead of water, and the mixed solvent ratio (weight ratio) of water: methanol was 80:20 (Example 15).
A polymerization experiment was performed in the same manner as in Example 2 except that the ratios were 0:40 (Example 16), 40:60 (Example 17), and the polymerization temperature was 15 ° C.

As a result, in each of Examples 15 to 17, poly (N-isopropylacrylamide) and XL
A uniform and tough organic-inorganic composite hydrogel composed of G, water and methanol was obtained. The transparency of the hydrogel after polymerization (measured at an ice bath temperature of about 1 ° C.) was determined in Example 15.
Was transparent and Examples 16 and 17 were opaque. In particular, Example 17 was completely white.

Thereafter, purification was carried out in the same manner as in Example 1 using pure water. After purification, Tc was measured using an organic / inorganic composite hydrogel swollen in water at 20 ° C. while changing the water temperature. As a result, all of the organic / inorganic composite hydrogels obtained in Examples 15 to 17 exhibited a critical temperature (Tc) at 33 ° C., below which colorless and transparent and swollen, and above Tc, white and opaque. Changes to
Volume contraction occurred.

From the above results, it was shown that the organic / inorganic composite hydrogel of the present invention can be obtained even when a mixed solvent of water and an organic solvent miscible with water is used. As a result of thermogravimetric analysis of the dried product, B / A (weight ratio) was 0.066 in all cases.

(Examples 18 to 21) In Example 18, except that the polymerization temperature was 50 ° C., Example 8 and Example 19
Then, polymerization was carried out in the same manner as in Example 9, Example 20, Example 10 and Example 21 in Example 11, and a uniform organic / inorganic composite hydrogel having toughness was obtained in each case.

The transparency at the polymerization temperature immediately after the polymerization was transparent in Examples 19 and 21, and Example 18 and Example 2 were transparent.
At 0, it was white and opaque. Then, when cooled to 1 ° C., Examples 18, 19 and 21 are transparent,
Example 20 was opaque to translucent. The resulting hydrogel was cut to a thickness of 25 mm and the total transmittance of visible light measured at 1 ° C. was 84% (Example 18), 93% (Example 19), 30% (Example 20), 88% (Example 2
1).

Example 22 As an organic monomer, N-
4.5 g of isopropylacrylamide (IPAA),
3.9 N, N-dimethylacrylamide (DMAA)
Water (85.3) was prepared in the same manner as in Example 8 except that 4 g was used.
g), XLG (2.98 g), TMEDA (72 μm)
l), a homogeneous solution containing PPS (4.77 g as an aqueous solution) was prepared and polymerized at 15 ° C. A resilient, uniform, translucent hydrogel was obtained.

No aggregation due to heterogeneous or opaque clay minerals or polymers was observed in the hydrogel.
Cut the hydrogel obtained by polymerization to a width of 25 mm,
As a result of measuring the transparency while changing the temperature, a change (LCST) from semi-transparent (total transmittance of about 40 to 35%) to opaque (total transmittance of 5% or less) was obtained at about 40 ° C to 50 ° C. occured. In Example 8 using IPAA alone, 32 ° C.
At 34 ° C., the change shifted from a transparent state (total transmittance: 90%) to an opaque state (total transmittance: 6%) rapidly, and the change shifted to a higher temperature side and became wider.

On the other hand, a hydrogel obtained by polymerization was cut into a rod shape having a diameter of 5.5 mm and a length of 30 mm, and was compressed to 1/3 and 1/5 in the thickness direction. Test to stretch to 4 times and 100 at center of length
, 150 ° and more. As a result, in each of the tests, the shape returned to its original state without being destroyed, cracked, or broken. In the bending deformation test, 180
After the test, the specimen returned to the original state without breaking, cracking, etc.

(Examples 23 and 24) The amounts of the water-swellable clay mineral XLG and the organic monomer IPAA were determined. In Example 23, XLG = 2.98 g, IPAA = 0.45 g, XLG /
IPAA = 6.62 weight ratio, and in Example 24, XLG = 0.0596 g, IPAA = 4.5 g, XLG
An experiment was performed in the same manner as in Example 8 except that / IPAA was set to 0.013. As a result, Example 2
In both Example 3 and Example 24, a homogeneous solution could be prepared, and as a result of polymerization, a uniform transparent gel was obtained. The total transmittance of the gel cut to a thickness of 25 mm was 95.1% (Example 23) and 9
8.2% (Example 24).

(Examples 25 and 26) Instead of XLG as a water-swellable clay mineral, Example 25 uses XLS (XLS
In which 6% by weight of sodium pyrophosphate was added with a deflocculant: Nippon Silica Kogyo Co., Ltd .; in Example 26, synthetic smectite SWN (manufactured by Corp Chemical Co., Ltd.) was used. An experiment was performed in the same manner as described above. As a result, in both Example 25 and Example 26, a homogeneous solution could be prepared, and as a result of polymerization, a uniform transparent gel was obtained. The total transmittance of the gel cut to a thickness of 25 mm is 90.
4% (Example 25) and 83.8% (Example 26).

Comparative Example 1 Polymerization was carried out at 20 ° C. for 15 hours in the same manner as in Example 1 except that no clay mineral was added. For both flat bottom glass containers and glass tube containers,
Only a colorless and transparent solution of poly (N-isopropylacrylamide) dissolved in water was obtained, and no gel was formed. When the temperature of the solution was raised, a polymer gel which became cloudy at about 32 ° C. or higher was obtained in a state separated from water, and when the temperature was lowered to 20 ° C., the solution returned to an aqueous solution again.

Incidentally, the confirmation of the polymer in the obtained solution was 5
L, diluted in water and kept in a water bath at 50 ° C. to make the lysate cloudy and aggregated, and centrifuged (20 ° C., 10,000 rpm,
(60 minutes), and further subjected to reprecipitation and purification using water, acetone, and hexane, followed by analysis of the sample (infrared absorption spectrum measurement, nuclear magnetic resonance spectrum measurement).

(Comparative Example 2) NaOH was added to adjust pH 11
Polymerization was carried out in the same manner as in Comparative Example 1, except that the colorless transparent solution of poly (N-isopropylacrylamide) was obtained as in Comparative Example 1, and no gel was formed. From this, the pH accompanying the addition of the clay mineral of Example 1 was obtained.
It was confirmed that there was no effect of the increase.

(Comparative Examples 3 and 4) Without using a clay mineral, after adding an IPAA monomer, an organic crosslinking agent was added to the IPAA.
20 ° C. in the same manner as in Example 1 except that 1 mol% (Comparative Example 3) and 5 mol% (Comparative Example 4) of AA were used.
For 15 hours. Organic crosslinking agents include N,
N'-methylenebisacrylamide (BIS) (manufactured by Kanto Chemical Co., Ltd.) was used as it was. In Comparative Example 3, a colorless transparent gel was obtained, and in Comparative Example 4, a cloudy gel was obtained. As a result of measurement in the same manner as in Example 1, {C / (A)} × 1
00 was 990% by weight (Comparative Example 3) and 935% by weight (Comparative Example 4), confirming that it was an organic crosslinked hydrogel.

In Comparative Example 3, Tc was around 33 ° C.
It was transparent and swelled at a temperature lower than Tc, and clouded and contracted at a temperature higher than Tc. The volume ratio between swelling and shrinking at 20 ° C. and 50 ° C. was about 8. On the other hand, in Comparative Example 4, even when the temperature was changed, all were in a cloudy state. Although it swelled on the low temperature side and contracted on the high temperature side at about 33 ° C., the volume ratio between swelling and shrinking at 20 ° C. and 50 ° C. was about 5
Met. FIGS. 1 and 2 show the state of changes in volume and total transmittance due to a temperature change in Comparative Example 4 together with the results of Example 1. FIG.

(Comparative Examples 5 and 6) 1 g of the poly (N-isopropylacrylamide) obtained in Comparative Example 1 was added to 10 g of water.
Mineral solution (Laponite XLG)
0.331 g (Comparative Example 5) or 0.066 g (Comparative Example 6) was added with stirring to prepare a composite composed of an organic polymer, a clay mineral, and water having the same composition as in Examples 1 and 2. In all cases, however, no hydrogel with uniform toughness was obtained.

(Comparative Example 7) Clay was added to a transparent aqueous solution obtained by dissolving 0.15 g of poly (N, N-diethylacrylamide) obtained in the same manner as in Comparative Example 1 except that DEAA monomer was used in 14.85 g of water. Minerals (Laponite XLG)
A clear solution in which 0.2 g was dissolved in 9.8 g of water was added while gradually stirring to prepare a mixture. When the aqueous solution of XLG is added up to 0.88 g (B / A = 0.117),
A white floating substance precipitated in the solution depending on the amount of XLG added, and turned into a cloudy solution. When the addition was further continued, for example, even when the added amount was 3.88 g (B / A = 0.517), the mixture remained a cloudy solution.

These turbid mixed solutions are heterogeneous solutions in which white aggregates are suspended in water.
It was observed that the turbidity further increased at a temperature higher than the temperature of ℃. However, in each case, a uniform hydrogel was not obtained. Further, even when the amount of added clay or the concentration of the initial polymer solution was increased, a uniform and tough hydrogel as obtained in the examples could not be obtained.

Comparative Example 8 A mixture containing an organic polymer, a clay mineral and water was prepared in the same manner as in Comparative Example 7, except that an aqueous solution of poly (N, N-diethylacrylamide) was gradually added to 10 g of an aqueous solution of XLG. Prepared. The addition and mixing resulted in a cloudy solution, and heating to a temperature higher than Tc only resulted in a heterogeneous solution with further increased cloudiness. In each case, a hydrogel with uniform toughness was not obtained.

(Comparative Examples 9 to 12) DEAA (Comparative Examples 9 and 10) or ACMO (Comparative Examples 11 and 12) was added without using a clay mineral, and an organic crosslinking agent N, N'-methylenebisacrylamide was used. (BIS) for DEAA or AC
Except for using 1 mol% (Comparative Examples 9 and 11) and 5 mol% (Comparative Examples 10 and 12) of MO, the same procedure as in Example 10 or Example 11 was carried out for 20 hours in a water bath at 15 ° C. To complete the polymerization.

In each of Comparative Examples 9 to 12, a hydrogel was obtained in which the entire system was gelled (the contents did not move even when the container was turned sideways) in the flask. No non-uniform aggregation was observed in the hydrogel.
The transparency of the hydrogel obtained by polymerization is determined by the ice bath temperature (about 1
° C), Comparative Examples 9 and 11 were uniformly transparent,
Comparative Examples 10 and 12 were opaque. The light transmittance of visible light of the hydrogel cut to a thickness of 25 mm was measured using Nippon Denshoku Industries Co., Ltd. NDH-300A,
Total transmittance 98% (Comparative Example 9), 24% (Comparative Example 1)
0), 98% (Comparative Example 11) and 22% (Comparative Example 12).

On the other hand, in Comparative Examples 9 to 12, polymerization was carried out under the above conditions using a glass tube having an inner diameter of 5.5 mm and a length of 150 mm as a polymerization vessel to obtain a rod-shaped organic crosslinked hydrogel. Cut out the obtained hydrogel into a rod shape with a length of 30 mm and compress it to 1/3 in the thickness direction, stretch it up to 2 times in the length direction, and bend and deform it to an angle of 100 degrees at the center point of the length A test was conducted.

As a result, in each of the samples of Comparative Examples 9 to 12, in the above test, cracks were generated, the shape was broken, and defects were generated. Further, the hydrogels obtained in Comparative Examples 9 to 12 were 5.5 mm in diameter (0.237 c in cross-sectional area).
m ² ), carefully cut out to 50mm in length, 10m up and down
m is sandwiched between round sandpapers without damaging and slipping, and a tensile test is performed using the same tensile test device as in Example 1 at a distance between gauge points of 30 mm and a tensile speed of 100 mm / min. However, the sample was fragile and most of the sample was broken before mounting on the chuck. In addition, even a device lightly attached to the chuck was broken immediately after the test, and no physical property value was obtained.

Comparative Examples 13 and 14: 5.5 mm inner diameter,
Except for using a glass tube container with a length of 150 mm,
In Comparative Example 13, a rod-shaped organic crosslinked hydrogel having an outer diameter of 5.5 mm was obtained by polymerization in the same manner as in Comparative Example 3 and in Comparative Example 14 in Comparative Example 4. A test to cut out the obtained hydrogel to a length of 30 mm and compress it to 1/3 in the thickness direction, a test to stretch to 2 times in the length direction, and a test to bend and deform to an angle of 100 degrees at the center of the length. went.

As a result, in each of the samples of Comparative Examples 13 and 14, in the above test, cracks were generated, the shape was broken, and defects were generated. Furthermore, cut out to a length of 50 mm, sandwiched by round sandpaper so that the upper and lower 10 mm were not damaged and slipped, and using the same tensile test apparatus as in Example 1, the distance between the gauges was 30 mm and the pulling speed was 1
An attempt was made to carry out a tensile test at 00 mm / min. However, the samples were brittle and any of the samples broke before being mounted on the chuck, and no physical property values were obtained.

Further, the obtained organic cross-linked hydrogel was added to about 5
Water content in the organic crosslinked hydrogel equilibrium-swelled in water at 20 ° C. after cutting into mm square water content {Cmax / (A)}
× 100 was 1500% by weight (Comparative Example 13) and 800% by weight (Comparative Example 14).

[0138]

According to the present invention, uniformity, transparency, mechanical properties,
Novel organic / inorganic hybrid hydrogel having excellent functions such as mechanical properties, water absorption, and swelling / shrinking properties, a method for producing the same, and an organic / inorganic composite obtained by removing water from the hydrogel.
A dried inorganic composite hydrogel can be provided.

The organic / inorganic composite hydrogel obtained in the present invention includes a tough and tough hydrogel, a transparent or uniform white hydrogel, a transparent and / or volume-swelled state at a low temperature, and an opaque and And / or a material having a critical temperature (Tc) that reversibly changes to a volume contraction state.
It can be reversibly converted back into a hydrogel by immersion in water, and is useful in a wide range of fields such as daily necessities, medicine / medical care, agriculture, civil engineering, and industrial fields.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in volume of an organic-inorganic composite hydrogel obtained in Example 1 and an organic cross-linked hydrogel obtained in Comparative Example 4 during swelling and contraction in water depending on temperature. The vertical axis indicates the volume (mm ³ ) of the hydrogel, and the horizontal axis indicates the temperature (° C.).

FIG. 2 is a graph showing changes in transparency of the organic / inorganic composite hydrogel obtained in Example 1 and the organic crosslinked hydrogel obtained in Comparative Example 4 depending on the temperature. The vertical axis indicates the total transmittance (%) and the horizontal axis indicates the temperature (° C.).

Claims (18)

[Claims] 1. A composition comprising three components of (A) a water-soluble organic polymer, (B) a water-swellable clay mineral which can be uniformly dispersed in water, and (C) water. An organic / inorganic hybrid hydrogel in which (C) is contained in a three-dimensional network consisting of B). 2. The organic / inorganic hybrid hydrogel according to claim 1, wherein the weight ratio of (B) a water-swellable clay mineral / (A) a water-soluble organic polymer is 0.01 to 10. 3. The organic / inorganic hybrid hydrogel according to claim 1, wherein (A) the water-soluble organic polymer is an organic polymer obtained by polymerizing an acrylamide derivative and / or a methacrylamide derivative. 4. A material having a critical temperature (Tc) that is transparent and / or volume swelled on a low temperature side and reversibly changes to an opaque and / or volume shrunk state on a high temperature side. 3. The organic / inorganic composite hydrogel according to any one of 3. 5. The organic / inorganic hybrid hydrogel according to claim 4, wherein the volume ratio of the hydrogel before and after the critical temperature (Tc) in water is 10 or more. 6. Measured using a hydrogel having a water content defined by {C / (A + B)} × 100 of 600 to 1000% by weight and an initial sectional area of 0.237 cm ² .
The tensile breaking load is 0.1 N or more, the tensile breaking elongation is 100% or more, and the load at 100% tensile elongation is 0.01 N or more, characterized by the above-mentioned. Organic / inorganic composite hydrogel. 7. The method according to claim 1, wherein the water content at equilibrium swelling in water at 20 ° C. {Cmax / (A + B)} × 100 is 2000% by weight or more. Organic-inorganic composite gel. 8. A method according to claim 1, wherein (A) contains 10 times (weight ratio) of water-soluble organic polymer (weight ratio), (C) water, and has a visible light transmittance of 80% or more at a thickness of 25 mm. Claim 1
5. The organic-inorganic composite gel according to any one of 5. 9. A dried organic / inorganic composite hydrogel obtained by removing water from the organic / inorganic composite hydrogel according to any one of claims 1 to 8. 10. A homogeneous solution comprising (A ′) a monomer of a water-soluble organic polymer (A), (B) a water-swellable clay mineral capable of being uniformly dispersed in water, and (C) water, A method for producing an organic-inorganic composite hydrogel, which comprises polymerizing (A ') in the presence of (B). 11. The organic / inorganic hydrogel according to claim 10, wherein the homogeneous solution containing (A ′), (B) and (C) further contains an organic solvent miscible with water. Production method. 12. The weight ratio of the (B) water-swellable clay mineral / (A ′) monomer of the water-soluble organic polymer (A) is 0.01 to 0.01.
The method for producing an organic-inorganic hybrid hydrogel according to claim 10 or 11, wherein 13. The organic compound according to claim 10, wherein (A ′) the monomer of the water-soluble organic polymer (A) contains an acrylamide derivative and / or a methacrylamide derivative. -A method for producing an inorganic composite hydrogel. 14. The obtained organic / inorganic hybrid hydrogel has a critical temperature (Tc) that is transparent and / or volume-swelled on a low temperature side and reversibly changes to an opaque and / or volume-shrinked state on a high temperature side. 11. The method according to claim 10, wherein
14. The method for producing an organic-inorganic composite hydrogel according to any one of items 13 to 13. 15. The method for producing an organic / inorganic composite hydrogel according to claim 14, wherein the volume ratio of the obtained organic / inorganic composite hydrogel before and after the critical temperature (Tc) in water is 10 or more. . 16. The obtained organic / inorganic hybrid hydrogel has a water content defined by {C / (A + B)} × 100 of 600 to 1000% by weight and an initial cross-sectional area of 0.237c.
It was measured using hydrogels m ^2, and tensile breaking load of 0.1N or more, a tensile elongation at break of 100% or more, and a tensile load at 100% elongation of claims 10 to 14 is at least 0.01N The method for producing an organic / inorganic composite hydrogel according to any one of the above. 17. The water content of the obtained organic / inorganic composite hydrogel at equilibrium swelling in water at 20 ° C. ΔCm
The method for producing an organic-inorganic composite gel according to any one of claims 10 to 14, wherein ax / (A + B)｝ x100 is 2000% by weight or more. 18. The obtained organic / inorganic composite hydrogel contains (A) 10 times (weight ratio) of water-soluble organic polymer (weight ratio), (C) water, and has a thickness of 25 mm. The light transmittance is 80% or more.
The method for producing an organic-inorganic composite gel according to any one of 0 to 14.