JPS6255542B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides high melting point isotactic poly-α-
This invention relates to a new method for producing a rubber composition with high elastic modulus and excellent tear resistance, which is made by blending olefin with rubber. In recent years, vulcanized rubber having a higher elastic modulus than the commonly used vulcanized rubber has become desired in certain fields. In this case, it is desirable that the physical properties of the rubber other than the elastic modulus are comparable to those of conventional vulcanized rubber, and that the processability in producing vulcanized rubber products is excellent. As a method to increase the elastic modulus of vulcanized rubber,
A method of mixing high elastic modulus substances (carbon black, resin, etc.) with rubber in the form of powder or fibers has been used. However, such a method is not sufficient in terms of dispersibility of the high modulus material, processability of the mixture, and vulcanized physical properties other than modulus, such as tear resistance. Recently, in an attempt to improve the elastic modulus and strength of rubber by microdispersing a resin in a rubber matrix, rubber compositions containing highly crystalline 1,2-syndiotactic polybutadiene have been shown to exhibit high elastic modulus. discloses that a rubber composition with excellent tear resistance and well-balanced physical properties can be obtained by a specific manufacturing method. For example, a two-stage polymerization method in which 1,3-butadiene is cis-1,4-polymerized and then 1,2-polymerized (Japanese Patent Publication No. 49-17666;
17667) or 1,2-syndiotactic polybutadiene powder is mixed with rubber and then treated at a temperature 5°C or more higher than the melting point of 1,2-syndiotactic polybutadiene (around 200°C) to form a string or sheet. Method of extruding into shapes (Japanese Patent Application Laid-open No. 53-126050)
There is. However, in the former case, it is difficult to control the physical properties of the polymer mixture, and the rubber is limited to cis-1,4-polybutadiene. In the latter case, various rubbers can be used, but special processing conditions such as high temperatures are required for rubber processing, and 1,2-syndiotactic polybutadiene easily gels at high temperatures. However, it is difficult to control the processing temperature. Furthermore, since the melting point of 1,2-syndiotactic polybutadiene is around 200°C, there is a practical problem when a high operating temperature higher than the melting point is required. The present inventors have achieved high elastic modulus by incorporating a crystalline polymer with better heat resistance than 1,2-syndiotactic polybutadiene without limiting the rubber used or requiring special processing conditions. As a result of intensive studies to obtain a rubber composition with high melting point and excellent tear resistance, we found that
- Olefin is blended into rubber in a specific way,
The inventors have discovered that a rubber composition with a high elastic modulus and excellent tear resistance can be industrially advantageously produced by microdispersing the rubber composition, leading to the present invention. That is, the present invention provides a high elastic modulus product characterized by mixing a rubber solution with a suspension dispersion obtained by stirring and dispersing a fine powder high-melting point isotactic poly-α-olefin with an average particle size of 200μ or less in an organic solvent. A method for producing a rubber composition having the following. The present invention will be explained in detail below. The high melting point isotactic poly-α-olefin used in the present invention is an isotactic poly-α-olefin having a melting point of 150°C or higher, preferably 160°C or higher. If the melting point is lower than 150°C, it will melt under the rubber vulcanization conditions, making it impossible to obtain good physical properties. Specific examples include isotactic propylene, polyallylcyclopentane, polyallylcyclohexane, polyallylbenzene,
Poly(3-methyl-1-butene), poly(3-cyclohexyl-1-butene), poly(4-phenyl-1-butene), poly(3-methyl-1-pentene), poly(4-methyl- 1-pentene), poly(3-methyl-1-hexene), poly(4-methyl-1-hexene), polyvinylcyclopentane and copolymers of propylene and allylbenzene,
Examples include copolymers of α-olefin and other α-olefins, such as copolymers of (3-methyl-1-butene) and 1-butene. Among these, isotactic polypropylene and poly(4-methyl-1-pentene) are preferred. It is preferable to use isotactic polypropylene especially for applications requiring tensile strength, and poly(4-methyl-1-pentene) for applications requiring particularly tear strength. Poly(4-methyl-1-pentene) can be synthesized, for example, using a Ziegler-Natsuta catalyst consisting of triethylaluminum-titanium tetrachloride (for example, Brit. P. 944055 (1963)). Melting point is 200
℃ or higher. Because poly(4-methyl-1-pentene) is highly crystalline, it is poorly soluble in ordinary hydrocarbon and halogenated hydrocarbon solvents near nitrogen temperatures.
The isotactic polypropylene used in the present invention is usually polymerized using, for example, a Ziegler-Natsuta catalyst (see, for example, G. Natsutta "Stereo Regular Polymerization", Pergamon Press).
, (1967)). The melting point is 150℃ or higher and the isotactic polymer content is 90% or higher. Preferably, the atactic polymer is separated and removed. In the present invention, the rubbers to be mixed with the isotactic poly-α-olefin having a high melting point are polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, butadiene-pentadiene-styrene rubber, ethylene-propylene copolymer rubber, and isobutylene-isoprene rubber. Examples include copolymer rubber and natural rubber, among which polyisoprene rubber, polybutadiene rubber, and styrene-butadiene rubber are preferred. The mixing method of the present invention employs a special method in which fine powder high melting point isotactic poly-α-olefin with an average particle size of 200 μm or less is dispersed in an organic solvent and mixed with a rubber solution. By this method, the polymer is uniformly mixed in the rubber in the form of fine particles, thereby achieving the object of the present invention. The fine powder high melting point isotactic poly-α-olefin used in the present invention with an average particle size of 200μ or less is obtained by adding powder or pellets of high melting point isotactic poly-α-olefin to an organic solvent and swelling it. A method in which the swollen product is vigorously stirred mechanically with an aqueous surfactant solution and then heated by steam ventilation to remove the organic solvent (powderization method), or isotactic poly-α-olefin is polymerized using a Ziegler-Natsuta catalyst. It can be obtained by a method of selecting particles having a particle size of 200 μm or less from the resulting fine powder slurry polymer (selection method), but is not limited to these methods. The high melting point isotactic poly-α-olefin used in the present invention must be a fine powder with an average particle size of 200 μm or less. If the average particle size exceeds 200μ, dispersion into rubber is poor and the physical properties of the rubber composition are significantly deteriorated. The preferred average particle size is 100μ or less, more preferably 50μ or less. In case of the above powdering method
It is possible and preferable to make the thickness 50μ or less. Examples of the organic solvent in which the fine powder high melting point isotactic poly-α-olefin is stirred and dispersed include solvents such as hydrocarbons and halogenated hydrocarbons. Specific examples include benzene, toluene, xylene, tetralin, hexane, heptane, octane, cyclohexane, methylene chloride, methylene dichloride, ethane tribromide, chlorobenzene, prombenzene, o-dichlorobenzene, and mixtures thereof. Among these, benzene, toluene,
Boiling points of hexane, heptane, cyclohexane, etc.
Hydrocarbon compounds having a temperature of 120° C. or lower are particularly preferred in terms of solvent recovery. On the other hand, as a solvent for dissolving rubber, any organic solvent that dissolves rubber can be used, and although it does not necessarily have to match the organic solvent in which the isotactic poly-α-olefin is dispersed, it is preferable to match it. is industrially advantageous. In the present invention, suspension dispersion refers to a state in which the fine particles of the polymer do not swell or have a low degree of swelling, and are diluted and suspended in a solvent, with the solvent simply acting as a dilution and dispersion medium. means. The concentration of polymer to be suspended and dispersed is usually 0.1 to 25
% by weight, preferably in the range of 0.1 to 10% by weight. The suspension dispersion can be obtained by mechanically mixing and stirring a finely powdered high melting point isotactic poly-α-olefin in an organic solvent. In order to prevent the agglomeration of fine powder and maintain a good dispersion state, for example, high-speed stirring with a toothed disk impeller blade or vigorous stirring at 2000 rpm or more using a Homomixer MV-H manufactured by Tokushu Kika Kogyo. It is preferable to do so. There are no particular restrictions on the temperature conditions at this time, but
It can usually be carried out at a temperature of 0 to 100°C. Examples of the rubber solution of the present invention include a rubber solution obtained by dissolving solid rubber in an organic solvent, and a rubber polymer solution obtained by polymerizing monomers in an organic solvent. This rubber polymer solution may contain a polymerization terminator or anti-aging agent, or may be diluted with a solvent. The solid content concentration of the rubber solution is usually 0.5 to 40% by weight, preferably 1 to 20% by weight. In the present invention, high melting point isotactic poly
Suspension and dispersion of α-olefin in an organic solvent and mixing with the rubber solution can be carried out by a commonly used method such as a method using a propeller type or turbine type stirrer. From the standpoint of efficient mixing, it is more preferable to use a high-speed stirrer as described in the section on suspension and dispersion preparation. The mixing order may be any method in which the rubber solution is added to the suspension of the high melting point isotactic poly-α-olefin that is stirred and dispersed, the reverse method, or both methods are mixed simultaneously. There are no particular restrictions on the mixing temperature, but it can usually be carried out at 0 to 100°C. The mixing time is not particularly limited as long as it is sufficient to uniformly mix both. There is no limit to the mixing ratio of high melting point isotactic poly-α-olefin and rubber, but in order to obtain a vulcanized rubber with high elastic modulus and excellent tear resistance,
High melting point isotactic poly-α- in the product
The olefin content is preferably 2 to 40% by weight. It is particularly preferably in the range of 3 to 30% by weight, and more preferably in the range of 3 to 25% by weight. If the content is less than 2% by weight, the effect of improving elastic modulus and tear resistance will be small, and if it exceeds 40% by weight, processability will deteriorate. The rubber composition after mixing can be recovered by a conventional method for recovering rubbery polymers. For example, methods include contacting with a large amount of non-solvent, or adding a surfactant and contacting with steam. The rubber composition obtained by the present invention can be used alone or in combination with other rubbers for rubber applications. Other rubbers used here include polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, ethylene-propylene rubber, butyl rubber,
Although natural rubber and the like are available, diene rubber or natural rubber is particularly preferred. When the rubber composition of the present invention is used for rubber applications, reinforcing agents and compounding agents that are commonly incorporated into rubber can be used. Furthermore, the processing and vulcanization methods used are those commonly used for rubber. Next, the present invention will be explained in detail with reference to Examples. Example 1 A swollen polymer prepared by swelling 1 part by weight of poly(4-methyl-1-pentene) (manufactured by ICI, melting point 235°C) with 20 parts by weight of toluene was mixed in a potassium rosinate aqueous solution using a high-speed mixer (Tokushu Kikaku Co., Ltd.). The mixture was stirred at 10,000 rpm (industrial homomixer MV-H type). In the latter half of the stirring, steam ventilation was performed to remove the solvent. In this case, potassium rosinate is poly(4-methyl-1
- Pentene) 3g was used per 1g. The powder thus obtained was recovered, washed with water, and then dried.
The average particle size was 20μ. This fine powder was mixed with n-hexane solvent (dispersion concentration
1.5% by weight) plus high speed mixer (10000rpm)
A hexane solution (solid content concentration 10% by weight) of polyisoprene rubber (IR-2200 manufactured by Nippon Gosei Rubber Co., Ltd.) was added in a suspended state while stirring and dispersing the mixture. Add a small amount of 2,6 di-t-butyl-p to the mixture.
- It was poured into a large amount of methanol containing cresol and coagulated. After drying the coagulated rubber composition in vacuum for a day and night, it was compounded according to the formulation shown in Table 1. After press curing at 145℃ for 20 minutes,
Tensile tests and tear tests were conducted according to JISK6301 to measure physical properties. The results are shown in Table 2. It can be seen that this rubber composition has good tear resistance and high elastic modulus. Table 1 Polymer 100 parts by weight Carbon black ISAF 50 Aromatic oil JSR AROMA 10 Zinc Flower 5 Stearic acid 1 Antioxidant 810-NA 1 Vulcanization accelerator CZ 1.5 Sulfur 2.5 Example 2 Polypropylene (Mitsubishi Yuka Co., Ltd. ), a swollen polymer swollen with 20 parts by weight of toluene was stirred with an aqueous potassium rosinate solution in a high-speed mixer (10,000 rpm). In the latter half of stirring, steam ventilation was performed to remove the solvent. In this case, 3 g of rosin potassium was used per 1 g of polypropylene. The powder thus obtained was collected and dried. Average particle size 25μ
It was hot. The obtained fine powder was added to n-hexane solvent (dispersion concentration 1.5% by weight), and while stirring and dispersing with a high-speed mixer (10000 rpm), a hexane solution of polyisoprene rubber (IR-2200) (polymer concentration 10 % by weight) and stirred and mixed. Post-treatment and blending of the mixture were carried out in the same manner as in Example 1. The results are shown in Table 2. It can be seen that this composition has good tear resistance and high modulus. Example 3 The same procedure as in Example 2 was carried out except that a toluene solution of BR01 (polybutadiene rubber manufactured by Nippon Synthetic Rubber Co., Ltd.) was used instead of the n-hexane solution of IR-2200 used in Example 2. It can be seen that this composition also has good tear resistance and high elastic modulus. Example 4 Instead of n-hexane solution of IR-2200
The same procedure as in Example 1 was conducted except that a toluene solution of SBR#1500 was used and the content of poly(4-methyl-1-pentene) in the rubber composition was 10% by weight. Comparative Examples 1 to 3 IR-2200, BR01, without mixing poly(4-methyl-1-pentene) or polypropylene
SBR#1500 was compounded according to the compounding recipe shown in Table 1. However, vulcanization is at IR-2200, and BR01 is at 145℃.
x 20 minutes, SBR#1500 is 145℃ x 60 minutes. Comparative Example 4 This is an example in which 10% by weight of polypropylene having an average particle size of 25μ obtained by the method of Example 2 was kneaded with IR-2200. This method has little effect on improving the modulus of elasticity and can only produce a rubber composition whose tensile strength is significantly reduced. Example 5 The same procedure as in Example 1 was carried out except that the content of poly(4-methyl-1-pentene) in the rubber composition was 10% by weight. Example 6 The same procedure as in Example 3 was carried out except that the content of isotactic polypropylene in the rubber composition was changed to 5% by weight. Comparative Example 5 The same procedure as in Example 2 was carried out except that an isotactic polypropylene powder having an average particle size of 350 μm was used. As in Comparative Example 4, only a rubber composition with little effect of improving the elastic modulus and with a large decrease in tensile strength was obtained. 【table】

Claims (1)

[Scope of Claims] 1. After mixing a suspension dispersion of finely powdered high-melting point isotactic poly-α-olefin with an average particle size of 200μ or less in an organic solvent with stirring and dispersion, and a rubber solution, a polymer mixture is mixed. 1. A method for producing a rubber composition having a high elastic modulus containing a high melting point isotactic poly-α-olefin, which comprises recovering the isotactic poly-α-olefin. 2. The method for producing a rubber composition according to claim 1, wherein the isotactic poly-α-olefin with a high melting point is poly(4-methyl-1-pentene). 3. The method for producing a rubber composition according to claim 1, wherein the isotactic poly-α-olefin having a high melting point is isotactic polypropylene. 4. The method for producing a rubber composition according to claim 1, wherein the rubber is polyisoprene rubber, polybutadiene rubber, or styrene-butadiene rubber. 5. The method for producing a rubber composition according to claim 1, wherein the content of the high melting point isotactic poly-α-olefin in the rubber composition is 2 to 40% by weight.