JPH04334539A - Hydrogel - Google Patents

Abstract

PURPOSE:To obtain a hydrogel having high strength and good elasticity by constituting the same from carboxyl group modified polyvinyl alcohol and a polyamine compound. CONSTITUTION:A polyamine compound (e.g. polyethylene-imine) is added to carboxyl group modified polyvinyl alcohol in a ratio of 0.05-30wt.% to be reacted therewith. The obtained hydrogel can easily control gel strength and water content and has high strength and good elasticity and is also excellent in safety. Especially, the hydrogel can be adapted to the medical field because the sterilized one can be easily prepared. As a concrete use, there is a medical material such as an artificial muscle, an artificial skin, a catheter, an anti- thrombogenic material, a drug sustained release carrier or an enzyme or bacterial cell immobilizing carrier. Further, the hydrogel can be adapted to a field requiring high water retentivity such as a water holding material, heat insulating material, an insulating heating medium, artificial bog moss, artificial soil for hydroponics, an artificial bait for fishery, a soil conditioner, an algicidal material, an antistaining material or an aroma sustained release carrier.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to hydrogels. More specifically, it relates to a novel polyvinyl alcohol (hereinafter abbreviated as PVA) hydrogel that has a high water retention rate, high strength, and exhibits rubber-like elasticity, and can be applied to fields such as fisheries, agriculture, civil engineering, and medicine.

0002

BACKGROUND OF THE INVENTION In recent years, the functions of hydrogels, which are molded bodies that do not dissolve in water in a hydrated state and have appropriate mechanical strength, have attracted attention, and the development of their applications has been studied. For example, medical materials such as soft contact lenses, pharmaceutical removable carriers, biological repair materials, artificial tendons, artificial skin, water retention materials, heat carriers for cold storage, artificial sphagnum moss, artificial soil for hydroponic cultivation, artificial bait for fishing, Possible industrial uses include soil improvement materials. Raw materials for such hydrogels include natural polymers such as starch, gelatin, and agar, and hydrophilic or water-soluble synthetic polymers such as PVA, polyacrylic acid, polyacrylamide, polyhydroxyethyl methacrylate, polyvinyl methyl ether, and polyvinyl pyrrolidone. is used. Agar gel production is well-known as an easy method for producing hydrogels. That is, to hot water or boiling water at 80-90°C,
0.1% by weight (hereinafter abbreviated as wt%) or more, for example 1
After dissolving ~10 wt% of agar, a hydrogel with a water content of about 90 to 99 wt% can be easily obtained by allowing it to cool to room temperature. Also known is a method in which boric acid, a boric acid aqueous solution, borax, a borax aqueous solution, or the like is added to a PVA aqueous solution to immediately gel it. Among these, PVA is the most excellent hydrogel raw material that has high mechanical strength even in a water-containing state, and has been studied extensively. For example, in Japanese Patent Application Laid-Open No. 60-177066,
A method for obtaining a high-strength PVA hydrogel is disclosed by freezing a concentrated aqueous solution of PVA at a low temperature of -5°C or lower for 5 hours or more, and then allowing it to crystallize at a relatively low temperature of 10°C or lower for 10 hours or more. There is. Also, JP-A-61-252
Publication No. 261 states that after dissolving PVA in a mixed solvent of water and an organic solvent, it is frozen and crystallized in a -20°C freezer for 3 hours, and then washed with water to obtain a tensile strength of 10K.
A method for obtaining a PVA hydrogel with a water content of 50 to 98 wt% and a water content of 50 to 98 wt% is disclosed. In addition, as a method for obtaining sterile gel, conventionally, a PVA aqueous solution or a PVA suspension aqueous solution containing propylene glycol, etc. was heated at 120°C.
, a method using pressurized steam treatment for 30 minutes, or a method in which the produced hydrogel was treated in an autoclave. Therefore, there were problems in terms of quality or performance as a hydrogel.

0003

[Problems to be Solved by the Invention] An object of the present invention is to provide a hydrogel that does not have any of the above problems.

[
0004

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors have developed a carboxyl group-modified PV.
A hydrogel consisting of A and a polyamine compound was found. The present invention will be explained in detail below. The viscosity average degree of polymerization (hereinafter abbreviated as polymerization degree) of the carboxyl group-modified PVA used in the present invention is preferably 500 or more, more preferably 1500 or more, and even more preferably 4000 or more. PV
The higher the degree of polymerization of A, the higher the strength of the hydrogel. If the degree of polymerization is lower than 500, the strength of the gel will be insufficient and the gel will lose its shape or collapse during repeated use, which is not preferable. The degree of saponification of PVA is preferably 88 to 100 mol%, more preferably 90 to 99 mol%, and 95 to 99 mol%.
More preferred is mole %. If the degree of saponification of PVA is less than 88 mol%, it will swell or dissolve significantly in water at room temperature, and the strength of the hydrogel in a water-containing state will also be extremely reduced.

Polyamine compounds used in the present invention include polyethyleneimine, polyethyleneamines [chain aliphatic polyamine H2N (CH2CH2
NH)nH, n=1: ethylenediamine, n=2: diethylenetriamine, n=3: triethylenetetramine,
n=4: tetraethylenepentamine, n=5: pentaethylenehexamine], cycloaliphatic polyamines such as menthene diamine, isophorone diamine, derivatives or modified products thereof, aromatic compounds such as metaphenylene diamine, diaminodiphenylsulfone Examples include polyamines, modified products thereof, aliphatic polyamide amines, and the like. Among these amine compounds, polyethyleneimine is particularly preferred. As polyethyleneimine, the following chemical formula 1
It is represented by , and has a molecular weight of about 300 to 100,000.

[Chemical formula 1]

[0006] The amount of the polyamine compound added to the carboxyl group-modified PVA varies depending on the mechanical strength required of the hydrogel, but is preferably 0.05 to 30 wt%. Liquid low molecular weight polyamine compounds can be used as they are, but high molecular weight polyamine compounds are
It is preferable to use it as a 0 wt % aqueous solution. In the present invention, it is presumed that the COOH group in the carboxyl group-modified PVA and the NH2 group in the polyamine compound form an ionic complex to produce a gel. The crosslinking reaction of carboxyl-modified PVA with a polyamine compound occurs easily even at room temperature, and the gel formation time and gel hardness can be controlled by the blending ratio of carboxyl-modified PVA and polyamine compound. This makes it possible to obtain even harder hydrogels. By performing heat treatment at a temperature of 100° C. or higher in an autoclave, an even harder hydrogel can be obtained by reacting the carboxyl group-modified PVA aqueous solution with the polyamine compound. As a method for obtaining the sterilized hydrogel of the present invention, carboxyl group-modified P
VA aqueous solution and polyamine compound in an autoclave
21°C for 20 minutes, 116°C for 30 minutes or 105°C
An example of this method is heating for 45 minutes. Further, by adding a porous substance to the hydrogel of the present invention, the strength of the hydrogel can be increased and the processability can be improved. The porous material may be either inorganic or organic. The particle size of the porous material is 0.1 to 200 μm.
Something of a certain degree is good. If the particle size is larger than 200 μm, repeated use may cause the gel to lose its shape or collapse. The amount of the porous substance added is preferably 1 to 200 wt%, more preferably 50 to 100 wt%, based on the carboxyl group-modified PVA. If the amount added exceeds 200 wt%, it may cause the gel to lose its shape or collapse. Examples of organic porous materials include polyacrylamide, polyimide resin, nylon powder, vinyl chloride resin powder, methacrylic resin powder,
Preferable examples include methyl methacrylate polymer beads, acrylic bead polymers, MBS resins, powdered NBR, polyethylene wax, polyethylene powder, fine particulate ultra-high molecular weight polyolefin powders, and fluororesin powders. Preferred inorganic porous materials include aluminum silicate, mica, magnesium oxide, white carbon, and activated carbon. Addition of these organic or inorganic porous substances has a great effect on increasing the strength of the hydrogel and improving the processability of the hydrogel. Water is preferred as a solvent for gelling carboxyl group-modified PVA in an autoclave. high temperature using an autoclave,
When reacting carboxyl group-modified PVA with a polyamine compound under high pressure, there is no problem with heat in the case of inorganic porous materials, but in the case of organic porous materials, the melting point of the polymer must be taken into consideration. It is necessary to set the temperature. In addition, when cooling the hydrogel in the ice chamber of a refrigerator or freezer, monohydric alcohol, polyhydric alcohol, glucose, sucrose, etc. are added to the carboxyl group-modified PVA aqueous solution to prevent the water in the hydrogel from freezing and causing the hydrogel to become rigid. May be added. These additives can be adsorbed onto organic or inorganic porous materials to provide suitable hydrogels. After producing the hydrogel in the autoclave, excess water or the above additives are removed, such as by filtration. Furthermore, the water content of the hydrogel can be adjusted to any desired water content by press filtration, centrifugation, or the like. When gelation is promoted at high temperatures, a hydrogel with a high degree of crosslinking can be obtained by adding a decomposition inhibitor for carboxyl group-modified PVA. The amount of decomposition inhibitor added is 0 for carboxyl group-modified PVA.
．． 1 to 5 wt% is preferable. If it is less than 0.1 wt%, there will be no decomposition inhibiting effect, and if it is more than 5 wt%, the strength of the hydrogel will be weakened. Furthermore, a water-absorbing resin such as sodium polyacrylate, isobutylene-maleic anhydride copolymer, or a water-absorbing gel may be added. The hydrogel of the present invention can be used unpackaged, encapsulated in a film or bag made of vinyl chloride, polyethylene, etc., or packaged. In the present invention, when preparing an aqueous solution containing carboxyl group-modified PVA, an inorganic or organic porous substance, and a metal salt compound with boric acid as a crosslinking agent, carboxyl group-modified PVA powder and crosslinking agent powder are prepared. , an inorganic or organic porous substance, a polyhydric alcohol, etc., are placed in an autoclave, and then a predetermined amount of water is added and dissolved by heating, whereby a hydrogel can be easily obtained. Furthermore, in order to obtain a better hydrogel, a greater improvement effect can be obtained if an organic or inorganic porous substance is treated with a monohydric or polyhydric alcohol in advance and then added. The hydrogel of the present invention has non-flowability, non-adhesiveness, high water content, and excellent mechanical strength. In addition, since the hydrogel itself has a fresh feel and extremely elasticity similar to konnyaku, it can be used as an ice pack with high elasticity, such as an ice pack.
It can be used as an alternative to ice bags. Further, the hydrogel of the present invention can be used in various fields because the hardness of the hydrogel can be adjusted by adjusting the amount of boric acid or an inorganic or organic porous substance added.

[0007]

[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples in any way. In the following examples, [parts] and [%] mean [parts by weight] and [% by weight], respectively, unless otherwise specified. Example 1 Carboxyl group-modified PVA (saponification degree 98.6 mol%,
Polymerization degree 1750, itaconic acid modification degree 1 mol%) and 10 parts of pure polyethyleneimine (manufactured by Nippon Shokubai Chemical Co., Ltd., trade name Epomin P-1000) with a molecular weight of 70,000 and 99 parts of water were used. A hydrogel was obtained by reacting at 90°C for 30 minutes. The obtained hydrogel was transparent and had a high water content and had konjac-like elasticity. Example 2 Carboxyl group-modified PVA (saponification degree 98.5 mol%,
Polymerization degree 1750, maleic anhydride modification degree 2 mol%)
A transparent hydrogel was obtained by reacting 95 parts of a 0% aqueous solution, 5 parts of the pure polyethyleneimine used in Example 1, 100 parts of water, and 2 parts of polyethylene glycol having a molecular weight of 600 at room temperature. The obtained hydrogel had an elastic body similar to konnyaku. Example 3 Carboxyl group-modified PVA (saponification degree 98.5 mol%,
Degree of polymerization: 4150, degree of itaconic acid modification: 1 mol%)
A hydrogel was obtained by heating 90 parts of the aqueous solution, 10 parts of the pure polyethyleneimine used in Example 1, and 1 part of the polyethylene glycol used in Example 2 at 60° C. for 1 hour. The resulting hydrogel had elasticity similar to konnyaku. This hydrogel was placed in a polyethylene bag, sealed, and placed in an ice chamber of a refrigerator to cool overnight to create an ice pack. When this ice pack was tested for repeated use, it was found to be in good condition with no syneresis and no deformation at all.

Example 4 Carboxyl group-modified PVA (saponification degree 98.8 mol%,
85 parts of a 5% aqueous solution of polyethyleneimine (polymerization degree 8000, itaconic acid modification degree 1 mol%), 13 parts of the 5% aqueous solution of polyethyleneimine used in Example 1, and 2 parts of the polyethylene glycol used in Example 2 were reacted at 50°C. A hydrogel was obtained. The resulting hydrogel had elasticity similar to konnyaku. Example 5 Carboxyl group-modified PVA (saponification degree 98.6 mol%,
Degree of polymerization 12000, degree of itaconic acid modification 1 mol%) 3%
70 parts of aqueous solution, polyethyleneimine with a molecular weight of 10,000 (manufactured by Nippon Shokubai Chemical Co., Ltd., trade name: Epomin SP-2)
00) and 2 parts of the polyethylene glycol used in Example 2 were reacted at 50°C to obtain a hydrogel. The resulting hydrogel had elasticity similar to konnyaku. Example 6 Carboxyl group-modified PVA (saponification degree 98.9 mol%,
Degree of polymerization: 18,000, degree of itaconic acid modification: 98.5 mol%)
A hydrogel was obtained in the same manner as in Example 5, except that 70 parts of a 3% aqueous solution of . The resulting hydrogel had elasticity similar to konnyaku. Example 7 5 of carboxyl group-modified PVA used in Example 2
% aqueous solution, 79 parts of the 5% aqueous solution of polyethyleneimine used in Example 1, and 1 part of the fragrance were reacted at room temperature for 60 minutes.
Moreover, a hydrogel was obtained that did not show syneresis at all even when strongly shaken. When we conducted a standing test on this fragrance-emitting hydrogel, we found that 6
The condition remained good for more than 0 days. Example 8 2 of carboxyl group-modified PVA used in Example 1
80 parts of 0% aqueous solution, 20 parts of polyethyleneimine with a molecular weight of 10,000 (manufactured by Nippon Shokubai Chemical Co., Ltd., trade name: Epomin SP-200) and 1 part of polyethylene glycol with a molecular weight of 1,000 were mixed in a stainless steel autoclave.
A hydrogel was obtained by reacting at 21° C. for 30 minutes. The obtained hydrogel was a konjac-like elastic body. In addition, a limulus test was conducted and the result was (-). This shows that it is sterile.

Comparative Example 1 Unmodified PVA (saponification degree 98.6 mol%, polymerization degree 175
0), 0.35 g of boric acid, and 70 g of distilled water were placed in an Erlenmeyer flask and dissolved by heating at 90° C. for 6 hours to obtain a crosslinked gel. The resulting gel was brittle and easily disintegrated when pinched with fingertips.

0010

Effects of the Invention The hydrogel of the present invention, which is composed of carboxyl group-modified PVA and a polyamine compound, allows easy control of gel strength and gel water content, and is also excellent in safety. In particular, since sterilized hydrogels can be easily produced, they are expected to be used in the medical field. Specific uses include medical materials such as artificial muscles, artificial skin, catheters, antithrombotic materials, sustained release carriers for pharmaceuticals, and carriers for immobilizing enzymes and bacterial cells, as well as water retention materials and cold storage materials. High water retention rate is required for materials such as wood, heat medium for cold storage, artificial sphagnum moss, artificial soil for hydroponic cultivation, artificial bait for fishing, soil conditioner, algae prevention material, antifouling material, and slow-release carrier for aromatics. It is possible to expand into industrial fields.

Claims (2)

[Claims] 1. A hydrogel comprising carboxyl group-modified polyvinyl alcohol and a polyamine compound. 2. The hydrogel according to claim 1, which is sterilized.