JPH0317844B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a novel powdery crosslinked carboxyl group-containing copolymer suitable for use as a thickener for various aqueous solutions. Conventionally, in order to produce such a polymer, a monomer having two or more ethylenically unsaturated groups in an α/β-unsaturated carboxylic acid such as acrylic acid, such as polyallyl ether of sucrose, hexaallyltri Methylene torsulfone, methylene bisacrylamide, triallyl cyanurate (U.S. Patent No.
2923692), tetraallyl silicon (U.S. Patent No.
No. 2985631), triallyl phosphate (U.S. Patent No.
3426004), tetraallyloxyethane (Tokuko Sho
56-443) etc. is known.
However, these polymers could not be said to be fully satisfactory in terms of performance. The present inventors have conducted intensive research on a new method for producing a crosslinked carboxyl group-containing water-soluble copolymer that has better thickening performance than conventionally known crosslinked copolymers. A method of crosslinking by copolymerizing an α/β-unsaturated carboxylic acid such as the following with a polymerizable monomer having a glycidyl group, and then reacting the carboxyl group and glycidyl group in the resulting polymer at an appropriate temperature. I found out. The thus obtained cross-linked copolymer, after being dissolved in water and neutralized to pH around 7 with an appropriate base, exhibits extremely high viscosity at a lower concentration than conventionally known copolymers, and can be used outdoors. It becomes a gel-like product that has good stability even when left for a long time and has plastic flow characteristics with a high yield value. The crosslinked water-soluble copolymer obtained by the present invention can be used as a solid suspension stabilizer for plaster, cement, etc., as a thickener for water-soluble paints and emulsion paints, as a sizing agent for printing in the textile industry, and in other fields. Useful as thickeners, gelling agents, dispersants, and adhesives in The polymerizable monomer having a glycidyl group used in the present invention is a monomer containing one or more epoxy groups and one or more ethylenically unsaturated groups, and is soluble in an organic solvent inert to this reaction system. If you have them, you can use them all. Specifically, they include glycidyl esters such as glycidyl acrylate, glycidyl methacrylate, glycidyl crotonate, and glycidyl oleate, and glycidyl ethers such as vinyl glycidyl ether, isopropenyl glycidyl ether, allyl glycidyl ether, and butenyl glycidyl ether. Particularly good results are obtained when using glycidyl acrylate and glycidyl methacrylate, which is economical. In order to obtain the desired thickening properties of the crosslinked water-soluble copolymer to be produced, the amount of these polymerizable monomers having glycidyl groups is determined, although it will of course vary depending on the type of crosslinking agent and other conditions. is in the range of 0.05 to 10% by weight based on the mixed monomer, preferably
It ranges from 0.1 to 3% by weight. The optimum amount to be added is determined depending on various conditions, and if it is added in excess, three-dimensionalization may progress too much and an insoluble gel may be produced. Furthermore, if the amount used is too small, there will be no effect and the liquid will exhibit properties similar to those without any crosslinking agent. The α/β-unsaturated carboxylic acids used in the present invention include acrylic acid, methacrylic acid, crotonic acid,
It is one type or a mixture of two or more types selected from the group consisting of maleic acid, itaconic acid, fumaric acid, sorbic acid, and other olefinic unsaturated carboxylic acids. Among these, acrylic acid is particularly preferred because it is inexpensive, easily available, and provides a polymer with excellent performance. The copolymerization reaction is carried out using a known organic radical catalyst in a solvent that dissolves the polymerizable monomer having α/β-unsaturated carboxylic acid and glycidyl groups, but does not substantially dissolve the resulting polymer, and is carried out at 20°C to The temperature is preferably 120°C, preferably 30°C to 90°C. Examples of solvents that can be used in the present invention include organic solvents that are inert to the copolymerization reaction itself, such as hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, chlorobenzene, ethylene dichloride, methyl isobutyl ketone, etc. Any mixture of the above solvent and other solvents can be used as long as it dissolves the monomer and does not substantially dissolve the copolymer. For example, benzene-dioxane mixtures and chlorobenzene-methanol mixtures can also be used advantageously. However, industrially, good results are always obtained when one selected from the group consisting of benzene, chlorobenzene, ethylene dichloride, etc. or a mixture thereof is used. The above-mentioned known organic radical catalysts are α・
α′-azobisisobutyronitrile (hereinafter referred to as AIBN), benzoyl peroxide, 2.2′-azobis2.4
-dimethylvaleronitrile, cumene hydroperoxide, tertiary butyl hydroperoxide, etc. The amount of these organic radical catalysts used varies depending on their type and temperature, but is usually in the range of 0.1 to 10% by weight, preferably in the range of 0.3 to 3% by weight based on the total amount of copolymerization raw materials. It is. If too much catalyst is used, the polymerization reaction will proceed extremely quickly, making it difficult to remove heat and making it impossible to maintain the desired temperature. In the present invention, an α/β-unsaturated carboxylic acid monomer and a polymerizable monomer having a glycidyl group are usually copolymerized, but if necessary, polymerization that can be copolymerized with the above two types of monomers is carried out. It is also possible to use sexual monomers. Methyl acrylate as a polymerizable monomer,
Good results may be obtained using alkyl acrylates such as ethyl acrylate. The copolymer in the present invention is usually produced according to the following formulation. The raw material monomer, copolymerization catalyst, and organic solvent are charged into a reactor equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a cooling tube. At this time, although the concentration of the copolymerization raw material varies depending on various conditions, it is suitably in the range of 20% by weight or less, preferably in the range of 5 to 15% by weight. If the concentration becomes very high, as the polymerization reaction progresses, precipitation of the polymer will become significant, making it difficult to remove heat from the system and making it impossible to uniformly stir the reactants. Next, nitrogen gas is blown into the solvent in order to remove oxygen dissolved in the upper space of the reaction vessel and in the raw materials. The polymerization reaction is initiated by heating to a predetermined temperature of 20° C. to 120° C. in a water bath or the like, and the inside of the reaction system gradually changes from an initial transparent homogeneous solution to a white slurry. In addition, apart from the above-mentioned method, a polymerizable monomer having a glycidyl group as a crosslinking agent can also be continuously added to the polymerization system as the polymerization progresses. After the polymerization reaction is completed, the precipitate is filtered,
Thoroughly wash with a suitable solvent and dry at a temperature of 50°C to 160°C. In this way, the crosslinked water-soluble copolymer is obtained in the form of a fine white powder with a low bulk specific gravity. In addition, since the crosslinking reaction of the polymer proceeds simultaneously during the drying process, an appropriate temperature range is determined as described above. Low-temperature drying under reduced pressure does not allow the crosslinking reaction to proceed, resulting in a product with low viscosity, while at high temperatures there is a risk that the polymer may undergo a decomposition reaction. Furthermore, if a large amount of water or α/β-unsaturated carboxylic acid as a raw material is present during drying, the resulting polymer may form lumps or become insoluble in water. Therefore, it is necessary to completely remove unreacted monomers in the step. By dissolving the crosslinked polymer obtained by the above treatment method in a large amount of water and neutralizing the carboxyl groups in the polymer to a pH of around 7 with an appropriate base, the aqueous solution exhibits the highest viscosity. The crosslinked water-soluble copolymer can be used at a concentration of 1% or less in water to obtain the desired viscosity, and its remarkable thickening effect is a major feature. Any known base can be used as a neutralizing agent; in addition to inorganic bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and ammonium hydroxide, organic bases such as triethanolamine and triethylamine are also used. It is possible. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Example 1 A three-dimensional acrylic acid polymer was produced according to the following recipe. Acrylic acid 30 parts Glycidyl methacrylate 0.2 parts Benzene 270 parts AIBN 0.3 parts The reaction was carried out at 60° C. for 3 hours under a nitrogen atmosphere.
The copolymer product was obtained as a white slurry, which was cooled, filtered, and thoroughly washed with benzene, the solvent used in the polymerization reaction. The cake was then dried at about 110°C to obtain a water-soluble copolymer in the form of a fine white powder. The powder was dispersed in a large amount of pure water (ion-exchanged water) and neutralized to pH 7 using an aqueous sodium hydroxide solution to prepare a viscous solution with a concentration of 0.3% by weight. When the solution was measured using a B-type rotational viscometer at 25° C. and a rotational speed of 6 rpm, the viscosity was 55,000 centipoise. Example 2 A white water-soluble polymer was obtained according to the method shown in Example 1 with the exact same recipe except that the following solvent was used instead of benzene. However, the solvent used in each reaction was used to wash the produced copolymer. These powders were dispersed in a large amount of pure water (ion-exchanged water) and neutralized to pH 7 using an aqueous sodium hydroxide solution to prepare a viscous solution with a concentration of 0.3% by weight. The viscosity of the solution was measured using a B-type rotational viscometer at 25°C and a rotational speed of 6 rpm, and the results shown in Table 1 were obtained.

[Table] Example 3 According to the method shown in Example 1, a three-dimensional acrylic acid copolymer was produced using the following recipe. Acrylic acid 30 parts Polymerizable glycidyl compound Ethylene dichloride shown in Table 2 270 parts AIBN 0.3 parts The reaction was carried out at 60° C. for 3 hours under a nitrogen atmosphere.
After cooling, it was filtered and further washed thoroughly with ethylene dichloride, which was the solvent used in the polymerization reaction. The cake was then dried at about 110°C to obtain a water-soluble copolymer in the form of a fine white powder. The powder was dispersed in a large amount of pure water (ion-exchanged water) and neutralized to pH 7 using an aqueous sodium hydroxide solution to prepare a viscous solution with a concentration of 0.3% by weight. The viscosity of the solution was measured using a B-type rotational viscometer at 25°C and a rotational speed of 6 rpm, and the results shown in Table 2 were obtained.

[Table] Example 4 A white water-soluble copolymer was obtained according to the method shown in Example 1 with the same recipe except that the type and amount of polymerization catalyst added and the polymerization temperature were changed as shown in Table 3. The results shown are obtained.

[Table] Example 5 30 parts of acrylic acid, 340 parts of ethylene dichloride,
0.3 parts of AIBN was charged into a reaction vessel and polymerized at 60°C under a nitrogen atmosphere. After the polymerization was started, a mixed solution consisting of 0.4 parts of glycidyl methacrylate and 100 parts of ethylene dichloride, which had been previously purged with nitrogen, was added dropwise over about 1 hour. Thereafter, polymerization was continued for 3 hours. Thereafter, the process was carried out in the same manner as in Example 3 to determine the viscosity.
A white, fine, water-soluble copolymer of 70,500 centipoise was obtained. Comparative Example 1 A fine white water-soluble copolymer was obtained using the same recipe as in Example 1 except that glycidyl methacrylate was changed to triallyl phosphate or tetraallyloxyethane. The viscosity of each copolymer produced is
It was 45,000, 53,000 centipoise. When these viscous liquids and the viscous liquid obtained in Example 1 were left outdoors for one week, the crosslinking agent using triallyl phosphate was 1000 centipoise, and the one using tetraallyloxyethane was 1800 centipoise. In contrast, that obtained in Example 1 was 15,000 centipoise.

Claims (1)

[Claims] 1 α/β-unsaturated carboxylic acid monomer 99.95-90
Weight% and polymerizable monomer with glycidyl group
0.05 to 10% by weight is copolymerized in the presence of a radical polymerization catalyst in an inert solvent that dissolves the monomer but does not dissolve the resulting copolymer, and then heat-treats the resulting polymer. A method for producing a crosslinked carboxyl group-containing water-soluble copolymer for use as a thickener. 2. The method according to claim 1, wherein the α/β-unsaturated carboxylic acid monomer is acrylic acid. 3. The method according to claim 1, wherein the polymerizable monomer glycidyl methacrylate has a glycidyl group. 4. The method according to claim 1, wherein the radical polymerization catalyst is α·α'-azobisisobutyronitrile. 5. The method according to claim 1, wherein the inert solvent is benzene. 6. The method according to claim 1, wherein the inert solvent is chlorobenzene. 7. The method according to claim 1, wherein the inert solvent is ethylene dichloride. 8. The method according to claim 1, wherein the inert solvent is a mixture of two or more selected from the group consisting of benzene, chlorobenzene, and ethylene dichloride. 9. The method according to claim 1, wherein the heat treatment is performed at a temperature of 50 to 160°C.