JPH05320425A - Polychloroprene rubber composition - Google Patents

Abstract

PURPOSE:To improve extrusion moldability and mechanical and electrical insulation properties by blending a polychloroprene rubber, a carbon black having a specific particle size, a fiber and a vulcanizing agent. CONSTITUTION:100 pts.wt. polychroloprene rubber is compounded with 10-50 pts.wt. carbon black having an average particle size of 85mum or less, 0.5-3 pts.wt. at least one fiber selected from among carbon, ceramic and aramid fibers and a small amount of vulcanizing agent, optionally together with a vulcanization accelerator, a softener and a filler, and kneaded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polychloroprene rubber composition suitable as a sheath material for captyre cables and the like.

[0002]

2. Description of the Related Art Generally, polychloroprene rubber has oil resistance,
Since it has excellent chemical resistance, it is widely used as a sheath material for, for example, a captyre cable. Since this cabtire cable is mainly used as a cable for temporary construction sites, it is susceptible to various external damages during its use. Therefore, the sheath material of the cable requires a high degree of mechanical performance.

In order to meet the demand for such mechanical performance,
Conventionally, various reinforcing agents have been added to polychloroprene rubber. Among them, carbon black is widely used because it has the largest reinforcing effect.

However, when a large amount of carbon black is mixed and kneaded with polychloroprene rubber for the purpose of improving the mechanical performance as described above, problems such as deterioration of scorch resistance due to increase in Mooney viscosity of unvulcanized rubber occur. Occurs. Further, in recent years, it has also been required that the sheath material of a captyre cable has good electric insulation in order to prevent an electric leakage accident. However, the sheath material made of the polychloroprene rubber composition in which a large amount of carbon black is blended with the polychloroprene rubber has a low electric insulating property, and is also not preferable in this respect.

When the carbon black is blended with the polychloroprene rubber to improve its mechanical strength as described above, a sufficient amount of mechanical strength is imparted to the resulting composition when the amount of the blend is small. In addition, the obtained composition exhibits a phenomenon of deformation or sagging during extrusion molding, resulting in deterioration of shape retention of the extrusion molded article. In addition, when compounded in a large amount, scorch resistance and electrical insulation are inferior, which causes a contradictory problem based on the compounding amount of carbon black, and a polychloroprene rubber composition that solves these contradictory problems has not yet been found. Of.

[0006]

DISCLOSURE OF THE INVENTION In the present invention, as a result of intensive studies in view of the present situation, as a result of improving extrusion moldability,
The molded product has developed a polychloroprene rubber composition having excellent mechanical performance and electrical insulation.

[0007]

The polychloroprene rubber composition of the present invention comprises carbon blacks 10 to 5 having an average particle diameter of 85 mμ or less with respect to 100 parts by weight of polychloroprene rubber.
0 parts by weight, 0.5 to 3 parts by weight of a mixture of any one or two or more kinds of fibers selected from the group of carbon fibers, ceramic fibers and aramid fibers and a small amount of a vulcanizing agent are mixed and kneaded. It is characterized by being harmonized.

[0008]

In the present invention, as the polychloroprene rubber, those commercially available may be used, for example, Neoprene TW (trade name, manufactured by Showa Denko KK and DuPont), SKYPRENE E-33 (Toso (stock) ) Company name, trade name).

In the present invention, carbon black is added for reinforcement, but the shape is limited to those having an average particle diameter of 85 mμ or less. The reason is that the mechanical performance of the polychloroprene rubber composition is not sufficiently improved when an average particle size of more than 85 mμ is used.

Examples of the carbon black include Diablack SH (manufactured by Mitsubishi Kasei Co., Ltd., trade name average particle size 22 to 30 mμ), Asahi # 55 (manufactured by Asahi Carbon Co., Ltd.,
The average particle size of the product is 49 to 84 mμ).

In the invention, therefore, the amount of the carbon black compounded is 10 to 100 parts by weight of polychloroprene rubber.
It is limited to 50 parts by weight, but the reason is that when it is less than 10 parts by weight, the mechanical performance of the obtained polychloroprene rubber composition is not improved, and when it is blended in a large amount exceeding 50 parts by weight. Is because the electrical insulation of the above composition is reduced.

In the present invention, in particular, one kind of fiber selected from the group of carbon fiber, ceramic fiber and aramid fiber or a mixed fiber of two or more kinds is added, but these fibers should be blended. This is because the mechanical performance of the polychloroprene rubber composition can be remarkably improved.

However, the blending amount of these fibers is also limited to 0.5 to 30 parts by weight with respect to 100 parts by weight of polychloroprene rubber, and when it is less than 0.5 parts by weight, the polychloroprene obtained is obtained. This is because the improvement in mechanical strength of the rubber composition is thin, and the mechanical elongation of the composition obtained is reduced when the rubber composition is compounded in a large amount in excess of 30 parts by weight.

Further, in the present invention, a small amount of a vulcanizing agent is added for vulcanization. Examples of the vulcanizing agent include zinc oxide, magnesium oxide and lead oxide. It is preferable to use magnesium oxide together.

Others In addition to the above components, the polychloroprene rubber composition of the present invention may optionally contain a vulcanization accelerator such as ethylenethiourea (Kawaguchi Chemical Co., Ltd., trade name Axel 22), tetramethylthiuram. Disulfide (manufactured by Ouchi Shinko Co., Ltd., trade name Nox Cler TT), nickel dibutyldithiocarbamate (manufactured by Ouchi Shinko Co., Ltd., Nocrac NBC), softeners such as alkylnaphthalene resin (Kenrich Chemical Co., Ltd., You may mix | blend brand name Kenflex A), a filler, for example, hard clay (made by Vanderbilt Co., USA, brand name Dekin clay), talc, calcium carbonate, and the like.

[0016]

EXAMPLES [Examples (1) to (5) and Comparative Examples (1) to
(7)] Based on the composition shown in Table 1, the respective components were sufficiently kneaded with a Banbury mixer to obtain a polychloroprene rubber composition of the present invention and a polychloroprene rubber composition of a comparative example.

The properties of the polychloroprene rubber composition of the present invention and the polychloroprene rubber composition of Comparative Example thus obtained are as follows: scorch resistance, unvulcanized product deformation rate, tensile strength, elongation volume resistivity and electric wire. Abrasivity was measured respectively. The results are as shown in Table 1.

[0018]

[Table 1] The numerical values of the compositions in Table 1 are all parts by weight.

Each component having the composition shown in the table is a product by a company shown in (A) below, and the performance of the polychloroprene rubber composition was measured based on the method shown in (B) below.

Note (A) (1) Carbon fiber: Branock (manufactured by Nippon Oil Co., Ltd., trade name) (2) Ceramic fiber: Ibiral (manufactured by Ibiden, trade name) (3) Aramid fiber: (Dupont (4) Asahi Thermal: Asahi Carbon Black Co., Ltd., carbon black average particle size 90 to 206 mμ (5) Zinc oxide: No. 1 zinc white (Mitsui Kinzoku Co., Ltd., trade name) (6) Oxidation Magnesium: Kyomag 150 (Kyowa Chemical Co., Ltd., trade name) Note (B) (1) Scorch property: According to JIS K6300, Mooney and scorch tests were conducted. That is, 125 ° C small rotor (MS125
5) of the unvulcanized rubber composition Mooney Scotch time
The point-up time (t ₅ ) was measured to determine the scorch resistance. If this 5-point increase (t ₅ ) is too short, scorch will occur during storage and extrusion.

(2) Deformation rate of unvulcanized rubber composition The deformation rate of the unvulcanized rubber composition was measured, and the shape-preserving property of the extruded product was judged by the magnitude of the deformation rate. The deformation rate of the unvulcanized rubber composition was measured by the following method. That is, a test piece having a length of 10 mm, a width of 10 mm, and a thickness of 10 mm was cut out from the kneading material immediately after kneading, and a load of 100 g / cm ² was applied to the dust test piece at 100 ° C. for 10 minutes, and the thickness after the load was measured .. Based on this measured value, the deformation rate was calculated by the following formula.

Deformation rate = initial thickness-thickness after loading / initial thickness × 100 If this deformation rate exceeds 30%, deformation or sagging occurs during extrusion.

(3) Tensile Strength and Elongation The unvulcanized rubber composition was vulcanized at 150 ° C. for 20 minutes to obtain a sheet having a thickness of ² mm under the conditions of a molding temperature of 150 ° C. and a molding pressure of 150 kg / mm ² . .. From this sheet JIS K6
A No. 3 bendal piece was cut out in accordance with 301, and the tensile strength and the elongation were measured.

(4) Electric insulation The volume resistivity of the test piece obtained according to JIS K6911 was measured.

(5) Abrasion resistance of electric wire An unvulcanized rubber composition was extrusion-coated to a thickness of 3 mm around an electric conductor having a cross-sectional area of 5.5 mm ^2.
After vulcanization at 20 ° C. for 20 minutes, it was cut into a length of 30 cm to obtain a test piece. Then, the abrasion amount (cc) of the test piece after rubbing under the condition of 400 rpm was measured by a JIS K3005 magnet abrasion tester.

As is clear from Table 1, Examples (1) to
The polychloroprene rubber composition of the present invention shown in (5) has a good durability scorch property, a small deformation ratio of the unvulcanized rubber composition, a large mechanical strength and elongation, and an electrical insulating property and wear resistance. It was shown to have excellent properties. In contrast, the polychloroprene rubber composition of Comparative Example was found to be inferior to any performance of the polychloroprene rubber composition of the present invention.

[0027]

The polychloroprene rubber composition of the present invention has excellent mechanical performance and electrical performance without impairing extrusion moldability, and is therefore suitable as a sheath material for cabtire cables and the like. The degree of damage to the sheath when the cable is used can be greatly reduced, and since it has excellent electrical insulation properties, it is industrially useful, such that there is no electrical leakage accident.

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Claims (1)

[Claims] 1. Carbon blacks 10 to 5 having an average particle diameter of 85 mμ or less based on 100 parts by weight of polychloroprene rubber.
0 to 3 parts by weight of a fiber selected from the group consisting of carbon fibers, ceramic fibers, and aramid fibers, and 0.5 to 3 parts by weight of a mixture of two or more kinds, and a small amount of a vulcanizing agent, respectively. A polychloroprene rubber composition characterized by being kneaded together.