JPH0593113A - Radiation-resistant elastomer composition - Google Patents

Abstract

PURPOSE:To prepare the title compsn. excellent in radiation resistance, processibility, and elasticity at a low cost by compounding an ethylene-propylene rubber with an ultraviolet absorber having tetramethylpiperidyl groups at both molecular ends. CONSTITUTION:The title compsn. is prepd. by compounding 100 pts.wt. ethylene- propylene rubber (e.g. an ethylene-propylene copolymer or an ethylene-propylene- diene terpolymer) with 0.1-50 pts.wt. ultraviolet absorber having tetramethylpiperidyl groups at both molecular ends (e.g. a compd. of formula I or II). The compsn. is free from blooming, thus preventing degradation in finish, and has an improve radiation resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation resistant elastomer composition which is used as a jacket for electric wires and cables (hereinafter simply referred to as "cable").

[0002]

2. Description of the Related Art A cable used in a radiation environment such as a nuclear power plant is required to have radiation resistance.
In particular, the control cables for manipulator operations for handling nuclear fuel and maintaining the core are exposed to extremely high radiation, and therefore higher radiation resistance is required.

This radiation resistance is mainly borne by an outer sheath (sheath), and as a polymer material for the outer sheath of this type of cable, conventionally, polyetheretherketone has been disclosed in Japanese Utility Model Publication No. 60-84024. (Hereinafter referred to as PEEK) is well known. However, this PEEK is expensive and has a problem of poor workability. In addition,
Elasticity is also required as a cable material.

Therefore, an object of the present invention is to provide a radiation resistant elastomer composition which has high radiation resistance, is inexpensive, and has excellent processability and elasticity.

[0005]

In order to solve the above problems, in the present invention, 100 parts by weight of ethylene / propylene rubber (hereinafter abbreviated as EP rubber) and tetramethylpiperidyl at both ends of the structural formula are used. The ultraviolet absorber having a group is added in an amount of 0.1 to 50 PHR.

The details will be described below.

The EP rubber in the present invention is a copolymer of ethylene and propylene (EPR) or a terpolymer (ER) obtained by adding a diene monomer to the copolymer.
PT) can be used, for example, EPT
1045 (trade name, manufactured by Mitsui Petrochemical Co., Ltd.) can be mentioned.

Further, the ultraviolet absorber having a tetramethylpiperidyl group at both ends in the structural formula in the present invention may be a compound represented by the following chemical formula 3 or chemical formula 4, for example, the chemical formula 3 Examples thereof include Sanol LS770 (trade name manufactured by Sankyo Co., Ltd.), and those shown by Chemical Formula 4 include Sumisorb TM-061 (trade name manufactured by Sumitomo Chemical Co., Ltd.).

[0009]

[Chemical 3]

[0010]

[Chemical 4]

The compounding ratio of the ultraviolet absorber represented by the above formula (3) or (4) to 100 parts by weight of EP rubber is
0.1 to 50 PHR, preferably 0.1 to 3 PHR for the chemical formula 3 UV absorber and 2 to 50 PHR for the chemical formula 4 UV absorber.

When the amount of the ultraviolet absorbent is less than the above range, the elongation is lowered and the resin is cured by receiving radiation. On the other hand, if it exceeds the above range, bloom (deposition on the surface) occurs, which is not preferable in appearance.

[0013]

In the elastomer composition according to the present invention having such a constitution, the radiation resistance is improved by adding the above-mentioned required amount of the ultraviolet absorber having tetramethylpiperidyl groups at both terminals of the structural formula.

[0014]

EXAMPLES The elastomer compositions of Examples 1 to 5 and Comparative Examples 1 to 6 were kneaded and prepared at the blending ratio (parts by weight) shown in Table 1 or Table 2. The kneading preparation, as a primary kneading,
With a test roll of 150 mmφ, 12 without cross-linking agent
Knead at 0 ° C for 20 minutes, then as secondary kneading, increase the temperature to 5
The temperature was lowered to 0 ° C., a crosslinking agent was added, and the mixture was kneaded for 10 minutes.

In Comparative Examples 6 and 7, a benzophenone-based UV absorber represented by the formula (5) below (Sumisorb 130 manufactured by Sumitomo Chemical Co., Ltd.) or a benzotriazole-based UV absorber represented by the formula (6) below. Each agent (Sumitomo Chemical 200, manufactured by Sumitomo Chemical Co., Ltd.) was used.

[0016]

[Chemical 5]

[0017]

[Chemical 6]

The resin composition thus obtained has a thickness of 1 mm,
Inner dimensions: 15mm x 150mm, put in a metal frame, 15
After press-crosslinking at 0 kgf / cm ² × 170 ° C. × 20 minutes,
By pressure cooling, a test sheet having a thickness of 1 mm × a length of 150 mm × a width of 150 mm was obtained.

The finished appearance (presence or absence of bloom) of this sheet was observed, and the elongation (El) at each γ-ray irradiation dose ( ⁶⁰ Co as a radiation source, dose rate 0.8 MR / hr. In air, at room temperature) and The results of measuring the tensile strength (Ts) are shown in the lower columns of Table 1 and Table 2. In the table, the units of El and Ts are% and kg / mm ² , circles and double circles are good, x is bad, blank is not measurable, and “original” is that without gamma irradiation. . The tensile test was performed according to JIS K6301 at a tensile speed of 200 mm / min.

[0020]

[Table 1]

[0021]

[Table 2]

From the results of this test, it can be understood that the elastomer composition according to the present invention is excellent in finishability and radiation resistance without generation of bloom at a specific blending ratio. Therefore, it can be sufficiently satisfied as an insulation coating for radiation-resistant electric wires and cables.

[0023]

Since the present invention is configured as described above, the radiation resistance is improved without suppressing the generation of bloom and causing the deterioration of the finishability.

Claims (3)

[Claims] 1. A radiation resistant elastomer composition comprising 100 parts by weight of ethylene / propylene rubber and 0.1 to 50 PHR of an ultraviolet absorber having a tetramethylpiperidyl group at both ends of the structural formula. 2. The ultraviolet absorbent is an ultraviolet absorbent represented by the following formula, and the compounding ratio thereof is 0.1 to 3 P.
The radiation resistant elastomer composition according to claim 1, which is HR. [Chemical 1] 3. The ultraviolet absorbent is an ultraviolet absorbent represented by the following formula, and the compounding ratio thereof is 2 to 50 PH.
The radiation resistant elastomer composition according to claim 1, which is R. [Chemical 2]