JPH03224628A - Base for gel - Google Patents

Abstract

PURPOSE:To improve the water and heat resistances and durability of a base for gel and to prepare high strength gel by forming the base with a polyvinyl alcohol-based polymer having >=55% syndiotacticity. CONSTITUTION:Vinyl ester having a bulky side chain or vinyl ester having high polarity, e.g., vinyl trifluoroacetate or vinyl ester represented by formula I (where R<1> is H or hydrocarbon, each of R<2> and R<3> is hydrocarbon and R<2> and R<3> may bond to each other to form cyclic hydrocarbon or R<1>, R<2> and R<3> may bond all together to form cyclic hydrocarbon) is saponified to synthesize a polyvinyl alcohol-based polymer having >=55% syndiotacticity. This polymer is molded into a sheet shape, etc., and cross-linked with radiation to form a base for gel.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-strength gel base material with excellent water resistance, heat resistance, and durability.

LJLLL1 set gels, especially polymer gels using water as a medium, have been known for a long time and have been applied in real life. Among them, the application to products has been very early, and various natural polymer gels are being used.

Recently, super absorbent gel, which is typified by disposable diapers and sanitary products,
Progress is being made in the development of gels that immobilize enzymes and bacterial cells, as well as biocompatible gels that can be used in contact lenses, artificial muscles, artificial organs, etc.

Furthermore, the development of basic gel science, represented by the discovery of the phase transition phenomenon of gels, has led to the development of new applications of gels as cutting-edge technology, such as functional gels such as sensor functional separation membranes, release control membranes, switches, actuators, etc. It suggests sex.

On the other hand, when looking at the polymeric compounds that are the base materials for gels, there are natural polymers represented by gelatin and various sugars, and synthetic polymers such as polyacrylic acid, polydihydroxyethyl methacrylate, polyacrylamide, and polyvinyl alcohol. However, recent new uses include gel strength,
Water resistance, heat resistance and durability are often required,
There is a need for a gel base material that can meet these requirements.

Problems to be Solved by the Invention Under these circumstances, the present invention seeks to provide a gel base material that is excellent in water resistance, heat resistance, and durability, and provides a high-strength gel.

As a result of intensive studies aimed at solving the above problem, the inventors of the present invention have found that a polyvinyl alcohol-based polymer containing 55% or more of syndiotuftin tea is excellent as a gel base material, and achieves the above problem. This discovery led to the completion of the present invention.

Here, the syndiotufting tea of the present invention is da-D
Fully saponified polyvinyl alcohol dissolved in MSO (
In the case of a partially saponified product, the triad tactility (measured on a completely saponified product) is determined from the NMR spectrum measurement of hydroxyl group protons, that is, isotufty city (I), heterotufty city (H).
and syndiotactic city (S) to i=I+H
/2, s = S + H/ 2, syndiotacticity calculated as:
(S). Note that i represents isotafticity.

Polyvinyl alcohol-based polymers have been used as base materials for gels since they can produce gels with high strength. The polyvinyl alcohol polymers conventionally used are so-called attack polymers, which have a syndiotacticity of approximately 53%. The gel base material of the present invention is a polyvinyl alcohol polymer containing 55% or more of syndiotuftin, and the gel using this polymer as a base material is a conventional polyvinyl alcohol polymer base material. Reflecting the fact that syndiotuftin tea is more expensive than gel, it is characterized by high water resistance, high heat resistance, high durability, and high strength.

The present invention will be explained in detail below.

The gel base material of the present invention is characterized by being a polyvinyl alcohol polymer with higher syndiotufting properties than the polyvinyl alcohol polymers used in conventional gels made of polyvinyl alcohol. In order to fully exhibit the effect of increasing syndiotuftin tea, it is necessary to increase the syndiotuftin tea content to 55% or more, preferably 57% or more, and more preferably 60% or more. Increasing the syndiotuftin tea improves the strength, melting point, water resistance, heat resistance, etc. of the gel, but if the syndiotuftin tea increases too much, problems may occur during gel manufacturing and processing processes. Because it is difficult to manufacture the polyvinyl alcohol polymer itself, syndiotuftin tea is 75%
% or less.

Polyvinyl alcohol polymers with such high syndiotacticity cannot be obtained by saponification of polyvinyl acetate, which is a common method for producing polyvinyl alcohol. The polyvinyl alcohol polymer with high non-diotactic protein used in the present invention has the following general formula [+
], saponification of polymers of vinyl esters with bulky side chains or highly polar vinyl esters such as vinyl esters represented by trifluoroacetate, vinyl trichloroacetate, vinyl formate, or polyvinyl esters such as t-butyl vinyl ether and trimethyl vinyl ether. Obtained by decomposition of ether.

3 (wherein R1 represents a hydrogen atom or a hydrocarbon group,
R1 and R3 each represent a hydrocarbon group, R'' and R3 represent a cyclic hydrocarbon group formed together, or R1, R1 and R3 represent a cyclic hydrocarbon group formed together R1, Rffi and R3 of the general formula [I] may represent each or together, for example, a lower alkyl group such as methyl, ethyl, propyl, butyl; phenyl, etc. Aryl group; preferably a hydrocarbon group having 1 to 18 carbon atoms such as cycloalkyl such as cyclohexyl.

Among these, it is easy to obtain a polymer with high syndiotacticity and a high degree of polymerization, and the decomposition reaction is easy, and the resulting polyvinyl alcohol polymer has good water resistance. Polyvinyl alcohol polymers from homopolymers or copolymers are preferably used.

Specific examples of vinyl esters include vinyl pivalate, vinyl dimethylethyl acetate, vinyl dimethylpropyl acetate, vinyl diethylmethyl acetate, vinyl triethyl acetate,
Trialkyl vinyl acetate such as tripropyl vinyl acetate and vinyl versatate; dialkyl vinyl acetate such as dimethyl vinyl acetate and diethyl vinyl acetate; cyclovinyl acetate such as methylcyclohexyl vinyl acetate; Examples include vinyl esters having alkyl, and vinyl pivalate and vinyl versatate are particularly preferred.

In the case of a copolymer, the comonomer units are divided into units that produce vinyl alcohol units by saponification and other units. The former units are copolymerized for the purpose of controlling toughness, and are copolymerized with vinyl esters such as vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl laurate, vinyl stearate, and vinyl benzoate. The amount of copolymerization is determined in relation to the amount of syndiotacticity. On the other hand, the latter comonomer is copolymerized mainly for the purpose of modification, and is used within a range that does not impair the spirit of the present invention, that is, 20 mol% or less, preferably 10 mol% or less, more preferably 5 mol% or less. Ru. Examples of such units include olefins such as ethylene, propylene, l-butene, and isobutyne, acrylic acid and its salts, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, and n-acrylate. -butyl, i-butyl acrylate,
Acrylic acid esters such as t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate, methacrylic acid and its salts, methyl methacrylate, ethyl methacrylate, methacrylic acid n
-Propyl, i-propyl methacrylate, n-butyl methacrylate, methacrylic acid layer -butyl, t-methacrylate
-Butyl, methacrylic acid esters such as 2-ethylhexyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate, acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetone acrylamide, acrylamide propanesulfonic acid and its salts, acrylamide propyldimethylamine and its salts or its quaternary salts, acrylamide derivatives such as N-methylolacrylamide and its derivatives, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid, its salts, methacrylamide propyldimethylamine and its salts or its quaternary salts, methacrylamide derivatives such as N-methylolacrylamide and its derivatives, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether , vinyl ethers such as i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether, nitriles such as acrylonitrile and methacrylonitrile, and vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride. , allyl compounds such as allyl acetate and allyl chloride, maleic acid and its salts or its esters, itaconic acid and its salts or its esters, vinyl silyl compounds such as vinyltrimethoxysolane, and isopropenyl acetate.

The polyvinyl alcohol-based polymer used as the base material for the gel of the present invention may be 55% or more of syndiotuftin tea as described above, but it may be 55% of syndiotuftin tea or more because it has particularly excellent hot water resistance. The vinyl ester unit represented by the above general formula [1] is 0.
A polyvinyl alcohol-based polymer having a content in the range of 0.01 mol% or more and 90 mol% or less, preferably 0.01 mol% or more and 70 mol% or less, is used. If the vinyl ester unit exceeds 90 mol%, the water content of the gel will decrease, and the gel strength will also decrease.On the other hand, if it is less than 0.01 mol%, the solubility of the polyvinyl alcohol polymer itself may be affected. Both are unfavorable as the performance is lowered.

The degree of polymerization of the polyvinyl alcohol polymer also affects the gel performance obtained in the present invention. From the viewpoint of gel strength and processing properties, the degree of polymerization is such that the intrinsic viscosity of polyvinyl acetate obtained by acetylating a polyvinyl alcohol polymer in benzene at 30°C is 0.3 di2/g or more, preferably 0.3 di2/g or more.
65 dC/g or more, more preferable L < Ha 0.98 dQ
/g or more, Mari 9. Odi! /g or less.

Gel as used in the present invention is a general term for chemically crosslinked or physically crosslinked polymer compounds containing water and organic solvents, and the gel base material of the present invention is particularly suitable for aqueous, nomethylsulfokind, dimethylformamide, It is preferably used for gels based on organic solvents such as dimethylacetamide, glycerin, ethylene glycol, and diethylene glycol.

Gels using the gel base material of the present invention can be prepared by various methods, such as a method in which a polyvinyl alcohol polymer is formed into a sheet shape, a sphere shape, etc., and then crosslinked with radiation or peroxide. , a method of cooling or freeze-gelling a solution or a swollen product of the polymer with a solvent (including a method of repeating freeze-thaw), suspension polymerization or precipitation polymerization to obtain a precursor of the polyvinyl alcohol polymer of the present invention, such as Examples include a method in which particles of polyvinyl pivalate are prepared and then saponified.

The gel base material of the present invention may be used alone or in combination with other polymers, including ordinary polyvinyl alcohol polymers, as long as the purpose of the present invention is not impaired.

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not in any way limited by the Examples. Note that "part" in the examples refers to 1 unless otherwise specified.
1 copy.

Example 1 A reaction vessel equipped with a stirrer was charged with 600 parts of vinyl pivalate monomer and 200 parts of methanol, and the system was purged with nitrogen by nitrogen gas bubbling. Separately, add 0.0% of 2,2'-azobisisobutyronitrile as an initiator to methanol.
A solution containing 0,712 parts was prepared, and the solution was replaced with nitrogen by bubbling with nitrogen gas. Raise the temperature of the reaction vessel to an internal temperature of 60℃.
When the temperature reached ℃, the initiator was dissolved and a methanol solution was injected to start polymerization. After 1.50 minutes, the polymerization rate was 4.
When the concentration reached 2%, the polymerization was stopped by cooling, and unreacted vinyl pivalate monomer was removed under reduced pressure while occasionally adding t-butanol to obtain a polyvinyl pivalate monobutanol solution. Subsequently, t-butanol was removed under reduced pressure to obtain a 45.7 vt % solution of vinyl polypivalate in tetrahydrofuran.

Next, add this solution 2 to a reactor equipped with a stirrer and a reflux condenser.
Measure out 1.9 parts, heat to 60°C, flush with nitrogen gas, maintain at 60°C, and add 21 parts of a separately prepared 25% methanol solution of potassium hydroxide that has been replaced with nitrogen. and stirred thoroughly. The system gelled in about 20 minutes, but after further holding at 60°C for 100 minutes, acetic acid 6.8
1 part with 20 parts of methanol to neutralize the potassium hydroxide. Subsequently, after pulverizing the gel, Soxhlet washing with methanol was performed to obtain polyvinyl alcohol. After adding 10 parts of acetic anhydride and 2 parts of pyridine to 0.5 parts of the obtained polyvinyl alcohol and sealing the tube, 12 parts of polyvinyl alcohol was added.
Acetylation was achieved by heating at 0°C for 8 hours. The obtained polyvinyl acetate was precipitated in n-hexane and purified by repeating reprecipitation twice in an acetone/n-hexane system. When the obtained polyvinyl alcohol was dissolved in d,-DMSO and NMR was measured, it was found that it contained 996 mol% of vinyl alcohol units, 0.4 mol% of vinyl pivalate units, and the syndiotacticity was 61.7. %Met. Further, the polyvinyl acetate obtained by acetylation was measured in benzene at 30° C. [η] was 1.17 d12/g.

This polyvinyl alcohol was dissolved in DMSO/water = 8°/20
(weight ratio) in a mixed solvent to prepare a 5wt% and 2vt% solution, and the solution was left at -10°C for 3 hours to obtain a gel. After 3 hours, the gel was immediately transferred to a 20°C bath and the melting temperature of the gel was measured. The measurement was carried out using a test tube with a diameter of 6.35aua and a weight of 1.06cm on the top of the gel prepared in a test tube with an inner diameter of 12.8I.
The melting temperature was measured by placing a steel ball of 100 g in weight and raising the temperature at a rate of 0.4 to 0.5° C./min, and setting the temperature at which the entire steel ball was buried in the gel as the melting temperature. The results are shown in Table I.

Comparative Example 1 [η] = 1.15dff as polyvinyl alcohol
/g.

Saponification degree 99.5%, syndiotacticity -53%
A gel was prepared in the same manner as in Example 1, except that a gel was used, and the melting point was measured. The results are summarized in Table 1.

Table 1 As is clear from the above results, the gel using the gel base material of the present invention has a higher melting temperature and excellent heat resistance than the conventional polyvinyl alcohol polymer gel. Another major feature of the present invention is that a high solvent content gel can be prepared by using the base material of the present invention.

Example 2 A reaction vessel equipped with a stirrer was charged with 870 parts by weight of vinyl pivalate monomer and 130 parts of methanol, and the system was purged with nitrogen by nitrogen gas bubbling. Separately, 2,2-azobisisobutyronitrile o as an initiator in methanol,
A solution in which the ogo part was dissolved was prepared, and the solution was replaced with nitrogen by bubbling with nitrogen gas. Raise the temperature of the reaction vessel until the internal temperature reaches 60℃.
When the temperature reached ℃, a methanol solution containing an initiator was injected to start polymerization. After 220 minutes, when the polymerization rate reached 30%, the polymerization was stopped by cooling, and after removing unreacted vinyl pivalate monomer under reduced pressure, methyl ethyl ketone was added to obtain a 20 part concentration polyvinyl pivalate solution in methyl ethyl ketone. .

Next, 15% of this solution was placed in a reactor equipped with a stirrer and a reflux condenser.
Weigh out 0 parts, 90 parts of methyl ethyl ketone and 60 parts of methanol, heat them to 60°C, flush them with nitrogen gas, hold them at 60°C, and then prepare separately prepared 25% potassium hydroxide which has been replaced with nitrogen. 63.6 parts of methanol solution was added and thoroughly stirred. The system gelled in about 13 minutes, but after being held at 60° C. for an additional 15 minutes, 25 parts of acetic acid was added along with 10 parts of methanol to neutralize the potassium hydroxide. Subsequently, after pulverizing the gel, Soxhlet washing with methanol was performed to obtain polyvinyl alcohol. 10 parts of acetic anhydride and 2 parts of pyridine were added to 0.5 parts of the obtained polyvinyl alcohol, the tube was sealed, and the tube was heated at 120° C. for 8 hours to acetylate. The obtained polyvinyl acetate was precipitated in n-hexane and purified by repeating reprecipitation twice in an acetone-n-hexane system. The obtained polyvinyl alcohol is d,
- When dissolved in DMSO and measured by NMR, it contained 80.6 mol% of vinyl alcohol units, 19.4 mol% of vinyl piperate units, and 6 mol% of syndiotuftin tea.
It was 1.5%. In addition, polyvinyl acetate obtained by acetylation was measured in benzene at 30°C [η is 1.75 dc/g
Met.

This PVA was dissolved in DMSO at 90°C to prepare an 8vt% solution, which was cast into a petri dish and left at 20°C for 3 hours to obtain a gel film. Subsequently, the operation of immersing it in a large amount of distilled water was repeated, and the solvent was replaced with water to obtain an aqueous gel. This gel was heated in 121'C water for 30 minutes, but no change was observed in the morphology of the gel, confirming that this gel had extremely excellent hot water resistance.

Example 3 150 parts of the methyl ethyl ketone solution of vinyl polypivalate obtained in Example 2, 90 parts of methyl ethyl ketone, and 60 parts of methanol were weighed into a reactor equipped with a stirrer and a reflux condenser, heated to 60°C, and nitrogen gas was added. After purging with nitrogen and holding at 60°C, separately adjusted and purging with nitrogen.
% of potassium hydroxide dissolved in methanol was added and stirred thoroughly. After maintaining the temperature at 60°C for 13 minutes, 25 parts of acetic acid was immediately added together with 10 parts of methanol to neutralize the potassium hydroxide.

Subsequently, after pulverizing the gel, Soxhlet washing with methanol was performed to obtain polyvinyl alcohol. 10 parts of acetic anhydride and 2 parts of pyridine were added to 0.5 parts of the obtained polyvinyl alcohol, the tube was sealed, and the tube was heated at 120° C. for 8 hours to acetylate. The obtained polyvinyl acetate was precipitated in n-hexane and purified by repeating reprecipitation twice in an acetone-n-hexane system. The obtained polyvinyl alcohol was dsDMs
When dissolved in O and subjected to NMR analysis, it was found to contain 53 mol% of vinyl alcohol units, 47 mol% of vinyl pivalate units, and diotacticity of 61.5%.

Further, [η] of the polyvinyl acetate obtained by acetylation was measured in benzene at 30° C. and was 1.75 dQ/g.

,: Dissolve the PVA at 90℃.
A wt% solution was prepared, cast in a Petri dish, and left at 20°C for 3 hours to obtain a gel film. Subsequently, the operation of immersing it in a large amount of distilled water was repeated, and the solvent was replaced with water to obtain an aqueous gel. This gel was heated in water at 121° C. for 30 minutes, but the morphology of the gel did not change at all, confirming that this gel had extremely excellent resistance to hot water.

According to the present invention, a gel having superior strength, water resistance, and heat resistance can be obtained compared to conventional gels based on polyvinyl alcohol polymers. Furthermore, the gel base material of the present invention is extremely useful as a base material for high solvent content gels. This is a gel base material containing 55
This effect was achieved for the first time by using a polyvinyl alcohol-based polymer of 55% or more, and this effect was particularly achieved by using a polyvinyl alcohol polymer with a polyvinyl alcohol content of 55% or more and a vinyl ester unit represented by the general formula [1] above. This is noticeable when a polyvinyl alcohol-based polymer containing .

The gel obtained using the base material of the present invention takes advantage of the above characteristics to be used in gels that immobilize enzymes and bacterial cells, contact lenses, etc.
It is used for biocompatible gels used in artificial muscles, artificial organs, etc., base materials for patches, sensors, functional separation membranes, release control membranes, functional gels for switches, actuators, etc.

Claims (2)

[Claims] (1) A gel base material made of a polyvinyl alcohol polymer with syndiotacticity of 55% or more. (2) The gel base material according to claim 1, comprising a polyvinyl alcohol polymer containing vinyl ester units represented by the following general formula [I]. [I]▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^1 represents a hydrogen atom or a hydrocarbon group,
R^2 and R^3 each represent a hydrocarbon group,
Or does R^2 and R^3 represent a cyclic hydrocarbon group formed together; R^1, R^2 and R^
3 represents a cyclic hydrocarbon group formed by joining together. )