JPH0328242A - Rubber composition reinforced with fine particle - Google Patents

Abstract

PURPOSE:To obtain a rubber composition improved in strengths, heat resistance and oil resistance by mixing a diene rubber with carbon black and spherical fine acrylonitrile particles of a specified particle diameter. CONSTITUTION:A solution of an acrylonitrile polymer is brought into contact with a nonsolvent of the acrylonitrile polymer by dispersion with a spray nozzle or the like to obtain spherical fine acrylonitrile particles of a mean particle diameter of 1-30mum. 50-80wt.% diene rubber (e.g. acrylonitrile/butadiene copolymer rubber) is mixed with 1-30wt.% carbon black and 5-40wt.% said particles to obtain a rubber composition reinforced with the fine particles and having a tensile strength >=300kg/cm<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyacrylonitrile-based fine particle reinforced rubber composition having excellent strength, heat resistance, and oil resistance.

(Prior Art) As a general method of increasing the strength of rubber, a method of embedding various reinforcing materials into rubber is known. However, these methods require a very complicated process because the long fiber female reinforcing material is first knitted into a woven tube or IJS, and then rubber is lined thereon. Therefore, if it were possible to reinforce rubber products by dispersing short fibers into rubber, the manufacturing process for the assembly would be to mix rubber, additives, and reinforcing short fibers, and then extrude or injection mold the mixture. It is expected that this method will be greatly simplified compared to the method using a woven or knitted fabric made of long fibers as described above.

For this purpose, for example, Japanese Patent Application Laid-Open No. 57-1063
No. 2 and Japanese Unexamined Patent Publication No. 58-103539 disclose techniques for reinforcing diene thread rubber with microorganic short fibers. However, in these methods, in order to produce a reinforcing effect, the glass transition temperature of the amorphous part must be below 30°C or above 120°C, the melting point of the crystalline part must be above 160°C, and the average short fiber length must be 0.8~3
It is necessary to add a special form of ultrafine fibre, with an average short fiber diameter of α02 to α8 μm. Specific examples of polymers constituting the microorganic fibers include intact polypropylene, poly-4-methyl-1-bentene, polyvinylidene fluoride, polyvinylidene chloride, poly-p-tert-butylstyrene, and poly-p. −
Chlorostyrene, polydichlorostyrene, poly-alpha-methylstyrene, poly-p-phenylstyrene, poly-10-vinylbenzyl alcohol, polyvinylnaphthalene, polyoxymethylene, polybisphenol A carbonate , 1.4 poly-2.5 dimethylbutadiene, etc. are only exemplified.

The technology of reinforcing the rubber composition by mixing organic short fibers into the rubber composition is already known, but when short fibers are added to rubber, the dispersibility of the short fibers into the rubber is always a problem. becomes. Therefore, there is a need for a technique for reinforcing rubber with a reinforcing material that can be easily dispersed into the rubber.

(Problems to be Solved by the Invention) In view of the above-mentioned current situation, the present inventors have developed a method for diene rubber as disclosed in the above-mentioned Korean Patent Publication No. 57-10652 and Japanese Patent Application Laid-open No. 58-103559. As a result of extensive research into what kind of organic reinforcing agent other than short microorganic fibers could be blended to create a reinforced rubber composition with excellent tensile strength, we found that diene thread rubber, carbon plaque, and acrylonitrile-based fine particles were combined with specific organic reinforcing agents. The present invention was achieved by discovering that the desired objective could be achieved by combining and blending the components in proportions within a range.

(Means for Solving the Problems) The gist of the present invention is that diene rubber 50-80
The present invention provides an acrylonitrile-based fine particle reinforced rubber composition comprising 1 liter of carbon black, 1 to 30 parts by weight of carbon black, and 5 to 40 parts by weight of true spherical acrylonitrile particles having an average particle size of 1 to 30 μm.

The acrylonitrile fine particles used in the present invention must have an average particle diameter in the range of 1 to 30 μm. When the average particle diameter is less than 1 μm, the fine particles tend to aggregate, and even if the particles are perfectly spherical, their dispersibility in rubber is significantly reduced.

If the average particle diameter exceeds 30 μm, the effective surface area of the particles is relatively reduced, and a sufficient reinforcing effect cannot be obtained.

In addition, the polymer composition constituting the acrylonitrile-based fine particles used should have 90 acrylonitrile units in view of its heat resistance. It is preferable that it is F4 or higher.

If the content of the characteristic particles in the acrylonitrile-based fine particle reinforced rubber composition is less than 5% by weight, there will be almost no reinforcing effect, while if the content exceeds 40% by weight, the resulting acrylonitrile-based fine particle reinforced rubber composition will have poor processability in the kneading process. It's bad and not good.

The acrylonitrile-based particles used in the present invention can be produced by dissolving an acrylonitrile-based polymer in a suitable solvent, dispersing it using a spray nozzle, etc., and coagulating it by contacting it with a non-solvent for the acrylonitrile-based polymer. This kind of technology is disclosed in Japanese Unexamined Patent Application Publication No. 1986-2-
No. 270631, JP-A-63-99238, JP-A-6
It is disclosed in publications such as No. 3-105054 and Japanese Unexamined Patent Publication No. 63-11-3043.

1. The diene rubbers used in the present invention include natural rubber, synthetic polyisoprene rubber, butyl rubber, halogenated butyl rubber, polyptadiene rubber, styrene-butadiene copolymer rubber, acryloni, IJ-butadiene copolymer rubber, and ethylene. Examples include -propylene-diene copolymer rubber, but acrylonitributadiene copolymer rubber is particularly preferred from the viewpoint of interfacial affinity with acrylonitrile-based fine particles.

The carbon black used in the present invention is not particularly limited, but examples thereof include rubber furnace carbon black (8PF, FBF, GBF). The carbon black content in the acrylonitrile-based fine particle reinforced rubber composition is carbon plaque 1 to 30.
It is necessary to have a heavy JJk%.

When the carbon black content is less than 1% by weight, the molded product obtained from the acrylonitrile-based fine particle reinforced rubber compound not only has a low tensile strength but also has significantly poor weather resistance. On the other hand 3
If the weight exceeds 0 weight t4, the workability is poor (unfavorable).

The acrylonitrile-based fine particle-reinforced rubber composition of the present invention may further contain compounding agents such as a vulcanizing agent, a promoter, a filler such as silica, and a softening agent within the range of usual formulations.

The acrylonitrile-based fine particle reinforced rubber introduction product of the present invention is
The above-mentioned I19 acrylonitrile-based fine particles, diene thread rubber, and carbon black are further added with various additives as required, subjected to pull heat treatment, and mixed in a mixer while vulcanizing.
Obtained by extrusion molding or injection molding.

(Example) Hereinafter, the present invention will be explained in detail according to Examples.

Examples 1 to 6, Comparative Examples 1 to 6 Rubber, fine particles, carbon black, and additives were mixed at the compounding ratio shown in Table 1, kneaded at 160°C for 20 minutes with a Banbury mixer, and then extruded at 160°C to obtain a diameter 3ms
, cut into 8 m long strands. This was further extruded into a sheet at 160° C. in order to sample a dumbbell test piece according to the test method described in J.Eng. SL6301. The physical properties and shape of the short fibers subjected to the test and the tensile test of the obtained rubber sheet were conducted in accordance with J.K. SK6501.

Table 1 The results are shown in Table 2.

In addition, the acrylonitrile-based fine particles in the table are disclosed in Japanese Unexamined Patent Publication No. 152
It was manufactured by the method disclosed in Japanese Patent No. -270631.

Table 2 Example 4, Comparative Example 4 The dumbbell test pieces used in Example 1 and Comparative Example 3 were
Placed in the dryer at °C. As a result of comparing the time at which the tensile strength retention rate becomes 50 or more at this time, the test piece of Example 1 was 1.4 times longer than the test piece of Comparative Example 3, and the acrylonitrile fine particle reinforcement of the present invention It was found that the rubber braided material also has excellent heat resistance.

Example 5, Comparative Example 5 The dumbbell test pieces used in Example 1 and Comparative Example 3 were
It was subjected to an oil resistance test at 40°C for 22 hours in accordance with K6501. As a result, the tensile strength retention rate of Example 1 was 6
On the other hand, the tensile strength retention rate of Comparative Example 3 was 58, and the swelling oil was 123, indicating that the acrylonitrile-based fine particle reinforced rubber composition of the present invention also has excellent oil resistance. I understand.

(Effects of the Invention) As described above, the acrylonitrile thread particle-reinforced rubber composition according to the present invention can be easily produced through a simple process, and the manufacturing process is significantly shorter than that of conventional fiber-reinforced rubber compositions. In addition to being simplified, the acrylonitrile-based fine particle reinforced rubber assembly has high tensile strength, heat resistance, and oil resistance, making it suitable for use in various rubber products such as hoses, packing, vibration isolating materials, and rubber materials. Since it shows suitability as a raw material, the industrial benefits are truly great.

Out wish Man Mitsubishi Rayon Co., Ltd.

Claims (1)

[Scope of Claims] 1. Acrylonitrile system consisting of 50-80% by weight of diene rubber, 1-30% by weight of carbon black, and 5-40% by weight of spherical acrylonitrile-based fine particles with an average particle diameter of 1-30 μm. Fine particle reinforced rubber composition. 2. The rubber composition according to claim 1, which has a tensile strength of 300 kg/cm^2 or more.