JPH05295175A - Polychloroprene rubber composition - Google Patents

Abstract

PURPOSE:To obtain the objective compsn. suitable as a sheath material of a cabtyre cable, etc. CONSTITUTION:100 pts.wt. rubber component comprising 60-90wt.% polychloroprene rubber and 10-40wt.% syndiotactic 1,2-polybutadiene, 10-50 pts.wt. carbon black having a mean particle size of 85mum or smaller, and a small amt. of a vulcanizing agent are mixed and kneaded to give the compsn.

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,
Because of its excellent chemical resistance, it is widely used as a sheath material for, for example, a captyre cable. Since the cabtyre rubber is mainly used as a cable for temporary construction sites, it is susceptible to various external damages during its use. Therefore, a high degree of mechanical strength is required for the sheath material of the cable.

In order to meet the demand for improvement in mechanical strength, various polychloroprene rubbers have been conventionally compounded with various reinforcing materials. Among them, carbon black is widely used because it has the largest reinforcing effect. is there.

However, when a large amount of carbon black is mixed and kneaded for the purpose of improving the mechanical strength of the polychloroprene rubber, problems such as a decrease in scorch resistance due to an increase in Mooney viscosity of the unvulcanized rubber occur. .. In recent years, it has been demanded that the sheath material of a captyre cable has good electric insulation to prevent an electric leakage accident. However, when a large amount of carbon black is blended with polychloroprene rubber and used as a sheath material. That is, the sheath material exhibits an unfavorable phenomenon that its electrical insulating property is deteriorated.

When a small amount of carbon black is added to solve these problems, the scotch resistance and electric insulation of the polychloroprene rubber composition are improved, but on the other hand, the mechanical strength is lowered and the extrusion molding is performed. There is a problem in that the shape retention during extrusion molding is inferior, that is, the deformation and sagging of the molded product sometimes occur.

These problems are contradictory issues regarding the amount of carbon black to be added, and a polychloroprene rubber composition which has solved these contradictory issues has not yet been found.

[0007]

DISCLOSURE OF THE INVENTION In the present invention, as a result of intensive studies in view of the present situation, a polychloroprene rubber composition having excellent mechanical strength and electrical insulation and having good extrusion moldability was developed. It was done.

[0008]

Means and Actions for Solving the Problems The present invention comprises 100 parts by weight of a mixture of 60 to 90 parts by weight of polychloroprene rubber and 10 to 40 parts by weight of syndiotactic 1,2-polybutadiene, and an average particle size of 85 mμ or less. 10 to 50 parts by weight of carbon black and a small amount of a vulcanizing agent are mixed and kneaded.

As the polychloroprene rubber in the present invention, those commercially available in general can be used. For example, Neoprene TW (trade name, manufactured by Showa Denko KK) or SKYPREN E-33 (Dupont ( Co., Ltd., trade name) can be listed.

The syndiotactic 1,2-polybutadiene is 1,2 obtained by polymerizing butadiene.
It is a thermoplastic polybutadiene containing 90% or more of bonds, and is commercially available, for example, under the trade name of JSR RB (manufactured by Nippon Rubber Co., Ltd.), RB810, 820, 830.
And the like, and RB820 is particularly suitable for improving the blendability with polychloroprene rubber and the mechanical strength.

The present invention comprises 90/1 of the above polychloroprene rubber and syndiotactic 1,2-polybutadiene.
It is compounded in a ratio of 0 to 60/40 because the reason is that when the polychloroprene rubber is less than 60 parts by weight and the syndiotactic 1,2-polybutadiene exceeds 40 parts by weight. The scorch resistance of the polychloroprene rubber composition decreases. On the contrary, when the syndiotactic 1,2-polybutadiene is less than 10 parts by weight and the polychloroprene rubber is more than 90 parts by weight, it is impossible to obtain sufficient mechanical strength of the obtained polychloroprene rubber. This is because.

The carbon black used in the present invention is limited to those having an average particle size of 85 mm or less because the carbon black having an average particle size of more than 85 mμ is used. This is because the obtained chloroprene rubber composition cannot obtain sufficient mechanical strength, and as such carbon black,
For example, DIA BLACK SH (manufactured by Mitsubishi Kasei Co., Ltd., trade name, average particle size 22 to 30 mμ) or Asahi # 55 (manufactured by Asahi Carbon Co., Ltd., trade name, average particle size 49 to 84 mμ) is commercially available. ing.

The blending ratio of carbon black is limited to 10 to 50 parts by weight with respect to 100 parts by weight of the mixture of polychloroprene rubber and syndiotactic 1,2-polybutadiene. The reason is that when the amount is less than 10 parts by weight, the mechanical strength of the obtained polychloroprene rubber composition cannot be improved, and when it exceeds 50 parts by weight, the electrical insulating property of the rubber composition is increased. This is because the

In the present invention, a small amount of a vulcanizing agent is added to the composition as described above for vulcanization. As the vulcanizing agent, for example, zinc oxide, magnesium oxide or zinc oxide can be used. .. Among these, it is preferable to use zinc oxide and magnesium oxide in combination.

Further, the polychloroprene rubber composition of the present invention may also be a vulcanization accelerator such as ethylene thiourea (Kawaguchi Chemical Co., Ltd., trade name: Axel), tetrathiuram disulfide (Ouchi Shinko Co., Ltd., trade name). Noxcellar TT), a softening agent such as an alkylnaphthalene resin (manufactured by Kenrich Chemical Co., trade name Kenflex A) and a filler such as hard clay (manufactured by Vanderbilt Co., USA, trade name dexclay), talc, calcium carbonate, etc. You may mix.

[0016]

【Example】

[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 give a polychloroprene rubber composition of the present invention and a comparison. Example A polychloroprene rubber composition was obtained.

Regarding the performance of the polychloroprene rubber composition of the present invention and the polychloroprene rubber composition of Comparative Examples thus obtained, the scorch resistance, the deformation rate of the unvulcanized composition, the tensile strength, the elongation, the volume resistivity and the electric wire Abrasivity was measured. 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. The syndiotactic 1,2-polybutadiene, Asahi Thermal, zinc oxide and magnesium oxide are products of the following companies. The performance of the polychloroprene rubber composition was measured based on the method shown below.

Note (1) Syndiotactic 1,2-polybutadiene:
JSR RB820 (Nippon Synthetic Rubber Co., Ltd., trade name) (2) Asahi Thermal: Asahi Carbon Co., Ltd. carbon black, average particle size 90 to 206 mμ (3) Zinc oxide: No. 1 zinc flower (Mitsui Kinzoku Co., Ltd.) , Trade name) (4) Magnesium oxide: Kyowamag 150 (Kyowa Chemical Co., Ltd., trade name) (5) Scorch resistance A Mooney scorch test was conducted according to JIS K6300. That is, 125 ° C small rotor (MS125 ° C)
The 5-point up time (t ₅ ) of the Mooney scorch time of the unvulcanized composition was measured with the above to determine the scorch resistance. If the 5-point up time (t ₅ ) is too short, storch is generated during storability and extrusion.

(6) Deformation rate of unvulcanized rubber composition The deformation rate of the unvulcanized rubber composition was measured, and the shape-preserving property of the extrusion-molded product was determined by the magnitude of the deformation rate. The deformation ratio of the unvulcanized rubber composition was measured by the following method. That is, a 10 mm long × 10 mm wide × 10 mm thick test piece was taken from the dough immediately after kneading, and a load of 100 g / cm ² was applied to this test piece for 10 minutes at 100 ° C., and the thickness after loading 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.

(7) Tensile Strength and Elongation The unvulcanized rubber composition was vulcanized at 150 ° C. for 20 minutes to a thickness of ² at a molding temperature of 150 ° C. and a molding pressure of 150 kg / mm 2.
I got a mm sheet. A No. 3 dumbbell piece was cut out from this sheet according to JIS K6301, and the tensile strength and elongation were measured.

(8) Electric Insulation Property The volume resistivity of the test piece obtained according to JIS K6911 was measured.

(9) Abrasion resistance of electric wire A conductor having a cross-sectional area of 5.5 mm ² was coated with a polychloroprene rubber composition to a thickness of 3 mm, and this was coated at 150 ° C.
After vulcanizing for 20 minutes, cut into 30 cm length and
The amount of wear (cc) after 400 rpm was measured by a SK3005 magnet wear tester.

As is clear from Table 1, Examples (1)-
The polychloroprene rubber composition of the present invention shown in (5) has good scorch resistance, a small unvulcanized rubber deformation rate, a large mechanical strength and elongation, and excellent electrical insulation and wear resistance. I showed that. On the other hand, it was confirmed that the comparative polychloropyrene rubber composition was inferior to any performance of the polychloroprene rubber composition of the present invention.

[0026]

According to the polychloroprene rubber composition of the present invention, since it has excellent mechanical performance and electrical performance without impairing the extrusion moldability, by using it for a sheath material such as a cabtire cable, 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.

Claims (1)

[Claims] 1. 60 to 90 parts by weight of polychloroprene rubber and 10 to 4 syndiotactic 1,2-polybutadiene.
A polychloroprene rubber composition comprising 100 parts by weight of a mixture with 0 parts by weight and 10 to 50 parts by weight of carbon black having an average particle diameter of 85 mμ and a small amount of a vulcanizing agent and kneading the mixture.