JPS6234326B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention applies acrylic acid to recycled rubber obtained by recycling natural rubber, polyisoprene rubber, styrene-butadiene rubber, copolymer rubber of ethylene and α-olefin, isoprene-isobutylene copolymer rubber, or vulcanizates thereof. The present invention relates to a method for obtaining a modified rubber by graft polymerizing or a derivative thereof. It has been known that natural rubber undergoes graft polymerization with vinyl monomers in the presence of a polymerization catalyst in its solution or latex state, and furthermore, when rubber is masticated with methyl methacrylate in a nitrogen stream, a graft polymer can be obtained. It is also known that
When masticating in air, the radicals generated by cutting the polymer chains due to mechanical shearing force react preferentially with oxygen in the air, stabilizing the radicals, resulting in less interaction with monomers. Graft polymerization is not initiated, and even if a polymerization initiator is present, graft polymerization is similarly not initiated due to the influence of oxygen. Modified rubber is produced by graft polymerization in a solid phase in air. The current situation is that this is difficult. The purpose of the present invention is to solve the above-mentioned problems and provide a method for easily producing a useful modified rubber with excellent adhesiveness and tensile strength by graft polymerization in solid phase air. It is. The present inventors have conducted intensive research on graft polymerization of acrylic acid or its derivatives with rubber through mechanochemical reactions using various organic peroxides as polymerization initiators, and have found that the temperature at which the half-life is 1 minute is When an organic peroxide with a temperature of 190 to 230°C and an amount of active oxygen in the molecule of 8 to 12% is used as a polymerization initiator, it is unexpectedly possible to use a kneading roll machine, Banbury mixer, or kneader in the air. Kneading is carried out in a kneading machine such as a kneading machine, and then heat treatment is carried out in the kneading machine, or heat treatment is carried out by transferring the kneaded material to another heating machine, whereby the graft polymerization reaction is carried out, and the adhesion and tensile strength are improved. It was discovered for the first time that a modified rubber for adhesion with excellent properties could be easily obtained. The present invention provides at least one rubber selected from natural rubber, polyisoprene rubber, styrene-butadiene rubber, copolymer rubber of ethylene and α-olefin, isoprene-isobutylene copolymer rubber, and recycled rubber of these rubbers with acrylic acid or When a derivative is graft-polymerized in the presence of an organic peroxide as a polymerization initiator, the organic peroxide preferably has a half-life of 1 minute at a temperature of 190 to 230°C and is contained in the molecule. In addition to using a substance with an active oxygen content in the range of 8 to 12%,
An adhesive with excellent adhesion and tensile strength, characterized by graft polymerization by kneading and heat treatment at 130 to 160°C, especially in solid phase and air, rather than in an organic solvent liquid phase or nitrogen stream. This is a method for producing modified rubber for use in industrial applications. In the present invention, the organic peroxide used as a polymerization initiator has a half-life of 1 minute (hereinafter simply referred to as half-life) of 190 to 230°C, and an amount of active oxygen contained in the molecule of 8 to 230°C. 2,5-dimethyl-2,
5-di(tert-butylperoxy)hexyne-
Examples include 3,1,1,3,3-tetramethylbutyl hydroperoxide, p-menthane hydroperoxide, and diisopropylbenzene hydroperoxide. Does the half-life exceed 230℃?190
An organic peroxide with a temperature below 0.degree. C. acts on rubber decomposition rather than a graft polymerization reaction, and an organic peroxide with an amount of active oxygen outside the above range also does not efficiently produce modified rubber. Among the organic peroxides used in the present invention, those with a half-life close to 190°C and an active oxygen amount close to 10% are more effective in acting on the graft polymerization reaction, and are therefore preferable. The amount of organic peroxide used is preferably in the range of 0.5 to 3 parts by weight per 100 parts by weight of the rubber to be modified. If the amount of organic peroxide is less than 0.5 parts by weight, the graft polymerization reaction is difficult to occur, and if it exceeds 3 parts by weight, the reaction becomes too vigorous and control of the reaction is often difficult, which is not preferable. Examples of acrylic acid derivatives include methacrylic acid, methyl methacrylate, ethyl methacrylate, and butyl methacrylate. The properties of the resulting modified rubber can be changed by selecting the type and amount of acrylic acid or acrylic acid derivative, but it is preferably used in an amount of 10 to 50 parts by weight per 100 parts by weight of the rubber to be modified. This is a preferable range because the modified rubber for adhesives with excellent adhesive properties and tensile strength obtained by the method of the present invention has both preferable rubber-like elasticity and thermoplasticity as described below. It is not particularly limited to this. Next, the operation for producing modified rubber in the present invention will be described. The rubber to be modified and acrylic acid or an acrylic acid derivative are kneaded using a rubber kneading machine such as a kneading roll machine, a Banbury mixer, or a kneader. There is no particular limit to this kneading temperature, but usually
The temperature is 40-80℃. Next, add a polymerization initiator and disperse it uniformly. Heat treatment can be continued by raising the temperature of the kneaded material in a kneader to 130-160°C and heating it for 20-30 minutes, or by taking out the kneaded material and forming it into a plate shape in another air oven or in a press. The graft polymerization reaction is completed by heating at 130 to 160°C for 20 to 30 minutes. The modified rubber obtained in the present invention has both rubber-like elasticity and thermoplasticity, and has various fluidities ranging from soft to hard. These properties can be varied depending on the type of rubber used and the type and amount of acrylic acid or acrylic acid derivative. Such modified rubber has desirable properties as a pressure-sensitive adhesive composition, an adhesive composition, or a molding material. Tests on the modified rubber of the present invention were conducted in the following manner. Fluidity was measured using a Koka-type flow tester at the outflow start temperature at a heating rate of 1°C/min and a load of 85.7 kg/ ^cm2 , and the elastic modulus and glass transition temperature at 20°C were measured using a torsion pendulum type viscoelasticity measuring device. Measured. The amount of graft polymerization is 3 times the modified rubber with hot water.
After extraction for 1 day, extraction was further performed with methanol for 1 day, and the amount is expressed as the added weight parts of acrylic acid or its derivatives based on 100 parts by weight of the rubber after extraction. Adhesive strength is 50 when bonded with a bonding area of 25mm x 25mm.
Shear peeling was carried out at a pulling rate of mm/min. In the present invention, by adding an organic peroxide with a half-life of 190 to 230°C and an amount of active oxygen in the molecule of 8 to 12% as a polymerization initiator, we have achieved The graft polymerization reaction of acrylic acid or its derivatives to rubber in the solid phase has been successfully carried out, and the manufacturing equipment is extremely advantageous because it can be used as is, using the equipment widely used in the rubber industry. In addition, the resulting modified rubber has both rubber-like elasticity and thermoplasticity, and has a range of hardness and fluidity, so it can be applied to adhesives, adhesives, molding materials, and other industrial materials. . EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Examples 1, 2, 3 Comparative Examples 1 to 6 100 parts by weight of recycled butyl rubber obtained by recycling automobile butyl tube waste (trade name: butyl recycled rubber, manufactured by Hayakawa Rubber Co., Ltd.) was wound around a kneading roll machine and the roll temperature was After roll kneading at 60°C with or without the addition of 30 parts by weight of methacrylic acid, organic peroxide was added as a polymerization initiator to regenerated butyl rubber 100%.
After adding 1 part by weight to each part by weight and further kneading to uniformly disperse the mixture, the kneaded product was taken out and heat treated in a press at 150°C for 20 minutes to obtain a modified rubber. The results are shown in Table 1. As shown in Table 1, when an organic peroxide with a half-life of 190 to 230°C and an amount of active oxygen in the range of 8 to 12% is used as a polymerization initiator, a graft polymerization reaction occurs. On the other hand, it can be seen that this reaction does not occur with other organic peroxides.

[Table] Examples 4, 5, 6 Comparative Example 7 2,5-dimethyl-2,5-di(tert-butylperoxy) was added as a polymerization initiator to 100 parts by weight of the same recycled butyl rubber as in Examples 1, 2, and 3. ) Using 1 part by weight of hexyne-3, methacrylic acid, methyl methacrylate, and butyl methacrylate were each 0,
Kneading was performed in the same manner as in Example 1 except that the amounts were changed to 10, 30, and 50 parts by weight, and the heat treatment was performed by taking out the kneaded product, forming it into a plate shape, and then heating it in an air oven at 140° C. for 30 minutes. Various properties of the obtained modified rubber are shown in Table 2. This shows that, with the exception of Comparative Example 7, graft polymerization occurs between the recycled butyl rubber and these acrylic acid derivatives in the solid phase and in the air, as in Example 1.

[Table] Example 7 Natural rubber (RSS#3), styrene-butadiene rubber (SBR1507 manufactured by Japan Synthetic Rubber Co., Ltd.), ethylene propylene rubber (trade name EPT1045 manufactured by Mitsui Petrochemical Industries, Ltd.), butyl rubber (manufactured by Nippon Butyl Co., Ltd.) (trade name IIR268), 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3,1,1,3,3- as a polymerization initiator.
The same treatment as in Example 1 was carried out except that tetramethylbutyl hydroperoxide or diisopropylbenzene hydroperoxide was used. All of the obtained modified rubbers were found to be more resistant to the Koka flow tester than rubber to which no methacrylic acid was added. The temperature at the start of outflow increased by 50 to 80°C, and the graft polymerization rate was 20 to 25 parts by weight, showing both rubber-like elasticity and thermoplastic properties. Comparative Example 8 The same rubber as in Example 1 was treated in the same manner as in Example 1 except that benzoyl peroxide, dicumyl peroxide, or di-tert-butyl peroxide was used as a polymerization initiator, but the resulting rubber All of the rubbers exhibited runoff onset temperatures that were almost the same as those of rubbers to which no methacrylic acid was added, and no graft polymerization occurred. Example 8 Comparative Example 9 100 parts by weight of recycled butyl rubber obtained from automobile butyl tube waste (trade name: butyl recycled rubber, manufactured by Hayakawa Rubber Co., Ltd.) was heated at 50 to 70°C without or with the addition of 30 parts by weight of methacrylic acid. After kneading with a kneader, 2,5-dimethyl-2.5-di(tert-
1 part by weight of (butylperoxy)hexyne-3 was added and further kneaded to achieve uniform dispersion. Thereafter, the temperature of the kneader was raised to 150°C and kneading was continued for 20 minutes to complete the reaction. The temperature at which methacrylic acid was added (Example 8) to which 30 parts by weight was added was 70% compared to the temperature at which methacrylic acid was added (Comparative Example 9).
℃ rose, and the graft polymerization rate was also 22 parts by weight in the latter case. Table 3 shows the physical properties of the rubber obtained in both cases and the adhesion properties when adherends were concrete mortar, plywood, and steel plates.

【table】

Claims (1)

[Scope of Claims] 1. At least one rubber selected from natural rubber, polyisoprene rubber, styrene-butadiene rubber, copolymer rubber of ethylene and α-olefin, isoprene-isobutylene copolymer rubber, and recycled rubber of these rubbers, and acrylic. In graft polymerizing an acid or a derivative thereof in the presence of an organic peroxide as a polymerization initiator, the organic peroxide is preferably one whose half-life is 190 to 230°C and whose intramolecular The active oxygen content is in the range of 8 to 12%, and the mixture is kneaded and heat-treated at 130 to 160°C, especially in the solid phase and in air, rather than in the liquid phase of an organic solvent or in a nitrogen stream. A method for producing a modified rubber for adhesive use, which is characterized by graft polymerization and has excellent adhesive properties and tensile strength.