JPS5885210A - Semiconductive molded article capable of thermally recovering - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-recoverable semiconductive molded article.

Conventionally, tape or the like has often been used for the internal semiconductive layer or the external semiconductive layer of the power cable joint.

Recently, semiconductive heat-shrinkable tubes have come into use due to their advantages such as smoothness of the surface after molding and ease of processing. Conventionally, semiconductive heat-shrinkable tubes have been made by blending a large amount of conductive carbon black with polyolefin resin. Normally, the conductivity required for a semiconducting layer is about 102 to 10'Ω·m in terms of volume resistivity.

When kneading conductive carbon black into resin, 40 to 70 parts by weight of a7ethylene carbon, which is well known as conductive carbon black, and 60 to 80 parts by weight of HAF carbon, which is usually used for reinforcement, etc. More mixing was needed. However, when carbon black is mixed, the viscosity increases when the materials are mixed, making processing for producing molded products extremely difficult. Furthermore, the elongation of the material itself is extremely reduced, making it extremely brittle as a molded product, and the expansion ratio for creating shrink-molded products becomes small, and in extreme cases, it cannot expand, making shrink-molded products cannot be created. The present invention is intended to improve this drawback, and its gist is to create a cross-linked resin composition containing 10-40 parts by weight of conductive carbon black per 100 parts by weight of a resin containing polycaprolactone as a main component. The present invention is a heat-recoverable semiconductive molded product in which strain caused by deformation under heating remains at room temperature.

It is a crystalline polymer. It was discovered that when conductive carbon black is blended with this polycaprolactone, good conductivity can be obtained with a small amount of carbon black, and the composition has excellent thermal recovery properties (strain due to deformation under heating at room temperature). For example, when a molded product is in the form of a tube, it can be given heat-shrinkable properties if the molded product expands under heating and the strain remains at room temperature. Examples 1 to 5 show formulation examples of resin compositions for the molded products.

The mixing torque at 180°C was smaller than Comparative Examples 1 to 5, which were low-density polyethylene mixed with the same carbon black and had similar conductivity, and the crosstalk torque was small, making processing easier. . Furthermore, a tube with an inner diameter of 10 m and a wall thickness of 2 uL was extruded and the electron beam was emitted for 25 m.
After being crosslinked by rad irradiation, the tube was heated at 150° C. and expanded by applying pressure inside the tube. Example 1~
It can be seen that the products using the present invention, such as No. 5, can be expanded to a greater extent than those having the same conductivity, such as Comparative Examples 1 to 5. (Tables 1 and 2) Furthermore, even if a mixture of not only polycaprolactone but also polyolefins such as ethylene propylene copolymer or ethylene-vinyl acetate copolymer is used as the resin, the results will be uniform as in Examples 6 to 8. The results of the present invention can be expected. However, when the amount of polyolefins is 50 parts by weight, the properties of the polyolefins become dominant as in Comparative Examples 6 to 8, and the resistance becomes large when the amount of carbon is used to maintain the same kneading torque and expansion ratio as in the examples. Therefore, the effects of the present invention cannot be expected. (Table 3) Crosslinking methods include high-energy ray irradiation crosslinking such as electron beam irradiation and gamma ray irradiation, chemical crosslinking in which a crosslinking agent such as an organic peroxide is mixed in advance, and heating is performed during molding, and water and moisture irradiation. A method such as that described in Japanese Patent Publication No. 48-1711, U.S. Pat. No. 3,075,948, in which a reactive group that reacts to cause a crosslinking reaction is introduced in advance, and after molding, it is exposed to moisture and crosslinked. It can also be taken away. Furthermore, the effects of the present invention are not impaired by the addition of anti-aging agents, ultraviolet absorbers, processing aids, flame retardants, etc., which are usually added for the purpose of preventing deterioration, improving weather resistance, etc.

) Table 2 WX-R: Anti-aging agent 2.4 Dithiobisdiphenol (manufactured by Sumitomo Chemical, trade name) PE DFD2005: Low density polyethylene (manufactured by Nippon Unicar, trade name) EVA D2011: Ethylene-vinyl acetate copolymer ( (manufactured by Juju Chemical, trade name) Mixing torque was measured at 180℃-4゜r using a Brabender.
Plaxel H-7 = Polycaprolactone molecular weight 70,000 (manufactured by Daicel Chemical, trade name) Plaxel H-4: Polycaprolactone molecular weight 40,000 (manufactured by Daicel Chemical, trade name) Denka Black: Acetylene carbon (Department of Electrochemistry,
Product name) Geest 300: HAF Carbon (Tokai Electrode Department,
Product name)

Claims (3)

[Claims] (1) Polymer 100 mainly composed of polycaprolactone
10 to 40 parts by weight of conductive carbon black
1. A heat-recoverable semiconductive molded article, which is a crosslinked molded article of a resin composition containing parts by weight, and is characterized in that distortion due to deformation under heating remains at room temperature. (2) A heat-recoverable semiconductive molded article according to claim (1), wherein the crosslinking is performed by irradiation with electron beams or γ-rays. (3) The heat-recoverable semiconductive molded article according to claim (1), wherein the polycaprolactone has a molecular weight of 40,000 or more.