JPS62112604A - Production of hydrogel - Google Patents

Abstract

PURPOSE:To produce a hydrogel which has good transparency and causes extremely small syneresis both at low temperature and at high temperature, by allowing an aqueous solution of an acetoacetylated water-soluble polymeric compound to gel by crosslinking with a specified crosslinking agent at room temperature. CONSTITUTION:An acetoacetylated water-soluble polymeric compound (e.g., PVA) is allowed to gel by crosslinking by mixing it with a crosslinking agent therefor [e.g., N-beta-(aminoethyl)-gamma aminopropyltrimethoxysilane]. Conventional natural gel products such as agar-agar or alginic acid require a step of dissolution by heating and, besides, the obtained gels have drawbacks of fragility, weakness and extremely poor transparency. A hydrogel obtained by adding boric acid or borax to a PVA solution has drawbacks of weakness and syneresis upon freeze-thaw cycle or upon prolonged storage at high temperature. According to the process of this invention, the obtained gel is advantageous in that it can be produced at room temperature and has good transparency and causes extremely low syneresis both at low temperature and at high temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective] The present invention relates to a method for producing an aqueous gel that can be produced at room temperature, has good transparency, and has extremely low water repellency at both low and high temperatures.

[Prior art and drawbacks]

When a few percent of agar is placed in water, heated and dissolved to form an aqueous solution, and then cooled, it gels into a pudding-like aqueous gel.

In addition, gelatin, alginic acid, carrageenan, etc. can be similarly gelatinized to obtain an aqueous gel.

These natural product gels require a step of heating and dissolving. Moreover, there is a drawback that the resulting gel is brittle and soft. Also, transparency is extremely poor. Gelatin also has the disadvantage of producing a glue odor. Also, when boric acid or borax is added to an aqueous solution of polyvinyl alcohol, an aqueous gel is obtained, but it is extremely soft, and if it freezes and thaws, remains at high temperature for a long time, or repeats freezing and high humidity, it will cause syneresis. There are drawbacks to doing so. Furthermore, there is a manufacturing disadvantage in that gelation tends to occur locally and it is difficult to obtain a uniform aqueous gel.

Means for Solving Problem C] In order to solve the above-mentioned problems, the present inventors have conducted extensive research on aqueous gels.

As a result, they discovered that aqueous solutions of acetoacetylated products of various water-soluble polymer compounds quickly gelled at room temperature with a specific crosslinking agent, producing a transparent aqueous gel.
The invention has been completed.

That is, the present invention is a method for producing an aqueous gel characterized by mixing an acetoacetylated water-soluble polymer compound, its crosslinking agent, and water to form a crosslinked gel.

The acetoacetylated water-soluble polymer compound used in the present invention is acetoacetylated water-soluble polymer compound such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose boxymethyl cellulose, or starch.

These can be used alone or in combination.

Taking polyvinyl alcohol as an example, methods for acetoacetylation of water-soluble polymer compounds include a method in which polyvinyl alcohol is dispersed in an acetic acid solvent, and a diketene represented by the following formula is added thereto. There is a method in which polyvinyl alcohol is dissolved in a solvent such as dimethyl formaldehyde or dioxane in advance and diketene is added thereto, and a method in which polyvinyl alcohol is brought into direct contact with diketene gas or liquid diketene.

The degree of acetoacetylation of the acetoacetylated water-soluble polymer compound is 1 mol% to 15 mol%, preferably 2 mol% to 1
A range of 2 mol% is suitable.

If it is less than 1 mol %, the crosslinking reaction will be difficult to proceed, making it difficult to obtain an aqueous gel, and if it exceeds 15 mol %, it will become difficult to dissolve in water depending on the type of water-soluble polymer compound, which is not preferable.

The crosslinking agents used in the present invention include compounds having an amine group, a compound having an aldehyde group, a compound having a dorazid group, a compound having an epoxy group, a compound having a methylol group, and metals such as titanium, zirconium, and aluminum. Examples include alkoxides and metal chelates. These may be used alone or in combination.

The compound having an amine group as a crosslinking agent used in the present invention has the general formula: %Formula% CH2 C112 NII2 , X and YltM number>
-cs-treated and having a molecular weight of 100 to 100,000, cycloaliphatic polyamines such as polyethyleneimine, diethylenetriamine, and triethylenetetramine, cyclic aliphatic polyamines such as menzendiamine and isophoronediamine, and derivatives or modified products thereof; Aromatic polyamines such as metaphenylene diamine and diaminodiphenylsulfone and modified products thereof, aliphatic polyamide amines and aminosilane compounds such as N-β(aminoethyl)γ-aminopropyltrimethoxysilane and γ-aminopropyltrimethoxysilane are used. suitable.

Compounds having an aldehyde group used in the present invention include monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, crotonaldehyde, benzaldehyde, and formamide; dialdehydes such as powdered glyoxal, malondialdehyde, glutaraldehyde, and terephthalaldehyde; Acrolein copolymerized acrylic resin is suitable. Among these, powdered glyoxal and glutaraldehyde are particularly preferred.

As the compound having a hydrazide group used in the present invention, dihydrazide compounds to polyhydrazide compounds are suitable; for example, dihydrazide compounds, organic salts of dihydrazide compounds such as formic acid and oxalic acid, methyl, ethyl, propyl, etc. of dihydrazide compounds, butyl,
monosubstituted with allyl, asymmetric disubstituted with 1,1-dimethyl, 1,1-diethyl, 4-n-butyl-methyl, and 1,2-dimethyl, 1,2-diethyl, 1,2-
Examples include symmetrically disubstituted compounds such as diisopropyl.

Particularly suitable hydrazide group-containing compounds are carbodihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sepacic acid dihydrazide, dotecaniic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, glycolic acid dihydrazide, polyhydrazide Acrylic acid hydrazide, etc.

The compound having an epoxy group used in the present invention includes:
Gepoxy compounds or polyepoxy compounds are suitable, such as ethylene glycol glycidyl ether, polyethylene glycol glycidyl ether, propylene glycol glycidyl ether, polypropylene glycol glycidyl ether, neopentyl glycol glycidyl ether, glycerol glycidyl ether, trimethylolpropane glycidyl ether, penta These include erythritol glycidyl ether, diglycerol glycidyl ether, sorbitol glycidyl ether, bisphenol A/epichlorohydrin type epoxy resin, and the like.

As the compound having a methylol group used in the present invention, a butylated urea resin initial condensate and a methylated or butylated melamine resin initial condensate are suitable.

The metal alkoxides used in the present invention include tetraethyl titanate, tetraethyl titanate, tetrabutyl titanate, tetra 2-ethylhexyl titanate, tetraethyl zirconate, tetrapropyl zirconate, tetrabutyl zirconate, and tetra 2-ethylhexyl. Zirconate, aluminum isopropylate,
Mono-5ec-butoxyaluminum diisopropylate and aluminum 5ec-butyrate are preferred.

The metal chelates used in the present invention include titanium lactate, di-propoxy bis(acetylacetone) titanate, di-n-butoxy bis(triethanolamine) titanate, tetraoctylene glycol titanate, zirconium tetraacetylacetonate, Ethyl acetoacetate aluminum diisopropylate, aluminum tris(ethyl acetoacetate)
is suitable.

Although it is a guess, a water-soluble polymer compound having an acetoacetyl group in the molecule and a compound containing an amine group may cross each other through a reaction mechanism as shown in the following formula? ! It forms a structure and gels by incorporating water to produce an aqueous gel.

A water-soluble polymer compound having an acetoacetyl group in the molecule and a compound containing an aldehyde group form a cross-linked structure through the reaction mechanism shown in the following formula, and gel by incorporating water, forming an aqueous gel. generate.

Shin 3 1; tl 3
A water-soluble polymer compound having an acetoacetyl group in the CH3CH3 molecule and a hydrazide group-containing compound form a crosslinked structure by a reaction mechanism as shown in the following formula, although it is a guess, and an aqueous gel is produced in the same manner as above. .

-O? “° 1 C83CH3 ↓ CH3CH3 Although it is a guess, a water-soluble polymer compound having an acetoacetyl group in the molecule and an epoxy group-containing compound form a crosslinked structure by the reaction mechanism shown in the following formula, to produce an aqueous gel.

CH3 Kano Kano CH3 Although it is a guess, the water-soluble polymer compound having 7 cetyl groups in the molecule and the methylol group-containing compound form a crosslinked structure by the reaction Bm structure as shown in the following formula, and the same as above. Produces an aqueous gel.

1.　　　　　　　c-.

CH3CH3 ↓ 111! A water-soluble polymer compound having an acetoacetyl group in the molecule and a metal alkoxide or metal chelate form a crosslinked structure as shown in the following formula, and an aqueous gel is produced in the same manner as described above.

All of the above reactions do not require any heating and proceed rapidly at room temperature to produce a transparent aqueous gel.

The aqueous gel of the present invention can contain an HA agent, an ultraviolet absorber, an antioxidant, a pH adjuster, etc. depending on the purpose.

These reactions proceed in 2 to 3 seconds at air temperature, producing an aqueous gel. Of course, the gelation time can be freely adjusted by adjusting the type and degree of acetoacetylation of the acetoacetylated polymer compound, the type and ratio of crosslinking agent used, the solution temperature and pH of both, and the like.

In addition, powdered acetoacetylated polymer compound,
An aqueous gel can be produced by mixing a powdered crosslinking agent, adding an appropriate amount of water when necessary, and stirring and dissolving the mixture. Furthermore, even when either one is an aqueous solution, an aqueous gel can be produced simply by mixing and stirring the two.

According to the production method of the present invention, there is no need for the process of heating and melting and then cooling to gel, as is the case with V-ten and carrageenan, and by simply stirring and mixing at room temperature, the product can be odorless, strong, and elastic. A transparent aqueous gel is obtained, and it is an excellent aqueous gel that does not release water even when frozen and thawed, kept at high temperatures, or repeatedly subjected to high temperatures and freezing.

The hardness of Erero aqueous gel can be adjusted from fluid and soft to tough and elastic hard by adjusting the type and ratio of crosslinking agent, solution concentration of both, PTL, etc. Can be controlled over a wide range. Therefore, the aqueous gel obtained by the production method of the present invention is
It can be used in a wide range of applications, including cushioning materials, excipients, poultices, soundproofing materials, heat insulation materials, bacterial culture media, and product window samples.

The present invention will be explained by giving Examples and Comparative Examples.

Example 1 Degree of acetoacetylation: 5.5 mol%, degree of saponification: 99 mol%
, N-
10 parts by weight of a 10% aqueous solution of β(aminoethyl)γaminopropyltrimethoxysilane was added, stirred and mixed at room temperature, and poured into a 100m x 100IRIR x 25mm container, resulting in an excellently transparent aqueous gel. It was returned.

At this time, the pH of the solution before gelation was 93, and the gelation time was 4.
It was a minute. Further, the penetration depth into the gel after leaving this gel at room temperature for one week was 311111 (static load of 2009/d). Furthermore, when this gel was left in a freezer at -20° C. for 24 hours to freeze and then thawed to room temperature, there was no syneresis at all. Further, when this gel was left in a thermostatic oven at 70° C. for 24 hours, there was no syneresis at all.

〔Test method〕

1) Gelation time: The time required for the viscosity of the mixture to reach 500 to 100 OCP (liter non-stirable range) at room temperature (25° C.) after adding and mixing the crosslinking agent.

2) Transparent Visual judgment O: Transparent △: Translucent Agent addition mixing 1
Weekly v! 2) 4) After leaving the water syneresis gel 100Q in a sealed state under the specified conditions,
The amount of separated water is measured and expressed as a percentage of the initial gel weight.

Freeze-thaw syneresis - After freezing by leaving in a freezer at 20°C for 24 hours, and thawing at room temperature, the water separation rate (%) High-temperature syneresis Water separation rate (%) after being placed in a constant temperature machine at 70°C for 24 hours Examples 2 to 10 Aqueous gels were obtained in the same manner as in Example 1 using the following aqueous solutions of acetoacetylated water-soluble polymer compounds and the following crosslinking agent aqueous solutions in combination as shown in Table 1. Its properties are shown in Table 1.

<Aqueous solution of acetoacetylated water-soluble polymer compound) Static PVA (acetoacetylated polyvinyl alcohol aqueous solution used in Example 1) AA-based 11EC (acetoacetylated and droxyethyl cellulose with degree of acetoacetylation of 4.1 mol%) (2% aqueous solution of
(2% aqueous solution of acetoacetylated methylcellulose) AA-based CHC (2% aqueous solution of J levoxymethyl cellulose with acetoacetylation degree of 3.8 mol%) 5% aqueous solution of solubilized starch) [Aqueous solution of crosslinking agent] AEAPT14S (10% aqueous solution of N-β(aminoethyl)γ-aminopropyltrimethoxysilane) GX (10% aqueous solution of glyoxal) COH
D (5% aqueous solution of carboxyhydrazide) PPGGE (10% aqueous solution of polypropylene glycol glycidyl ether) Bt-HE (10% aqueous solution of butylated melamine resin) TAT (10% aqueous solution of di-n-butoxybis(triethanolamine) titanate) % aqueous solution] 1'LA (10% aqueous solution of ditanium lactate) (blank below) Procedural amendment (spontaneous) December 23, 1985 1 Indication of case 1985 Patent application No. 252488 2 Name of invention Aqueous Relationship with Dell's Manufacturing Method 3 Amendment Case Patent Applicant 4 Agent 540 5 Subject of Amendment (1) Column 6 "Detailed Explanation of the Invention" of the Letter of Indication 6 Contents of Amendment (1) ) On page 16, line 7 of the specification, "for 10 parts by weight" is corrected to "for 190 parts by weight."

that's all

Claims (1)

[Scope of Claims] 1. A method for producing an aqueous gel, which comprises mixing an acetoacetylated water-soluble polymer compound, its crosslinking agent, and water to form a crosslinked gel. 2 The water-soluble polymer compound is polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, carboxymethyl cellulose,
The method for producing an aqueous gel according to claim 1, wherein the aqueous gel is one or more selected from starches. 3. The crosslinking agent is selected from compounds having an amine group, compounds having an aldehyde group, compounds having a hydrazide group, compounds having an epoxy group, compounds having a methylol group, metal alkoxides such as titanium, zirconium, aluminum, and metal chelates. The method for producing an aqueous gel according to claim 1, wherein the number of aqueous gels is one or more.