JPS62124135A - Heat-resistant polyolefin resin composition - Google Patents

Abstract

PURPOSE:To obtain a composition giving a molded article resistant to blooming and having high heat-resistance, by compounding a polyethylene resin or a copolymer resin composed mainly of ethylene with a polybutene and an antioxidant. CONSTITUTION:100pts.wt. of a resin containing 65-90(wt)% polyethylene resin or copolymer resin composed mainly of ethylene and 10-35% polybutene is compounded with >=0.5% antioxidant such as a compound containing phenolic group, thioether group, phosphorous acid group, etc. The composition is crosslinked to form a molded article.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a heat-resistant polyolefin resin composition.

[Prior Art] Recently, wires and cables used for electronic and electrical equipment, and tubes used for covering terminals, require not only good physical properties but also a high degree of heat resistance. This is becoming more and more common.

Heat resistance here refers to satisfying two conditions: (+) small deformation at high temperatures, and (2) small deterioration of properties due to deterioration even if exposed to high temperature atmosphere for a long time. be.

Polyethylene resins and copolymer resins mainly composed of ethylene have good mechanical and electrical properties, but the above (1)
) Crosslinking using peroxide or crosslinking by irradiation with high-energy radiation is adopted to achieve the condition (2) above, and the use of antioxidants and inhibitors to suppress radical reactions to achieve the condition (2) above. has been adopted.

[Problem to be solved by the invention] Regarding the latter, however, the effect improves as the amount of antioxidant added increases, but if the amount added exceeds the solubility in the resin, the antioxidant precipitates on the resin surface (this This phenomenon is called blooming or migration), which impairs the appearance and poses the problem of contamination to those who handle it.

The present invention has been made based on the above, and aims to provide a heat-resistant polyolefin resin composition that has a high degree of heat resistance and does not cause blooming of antioxidants.

[Means for Solving the Problems] The resin composition of the present invention has a resin content of 100 parts by weight containing 65 to 90% by weight of polyethylene resin or a copolymer resin mainly composed of ethylene and 10 to 35% by weight of polybutene. On the other hand, it is characterized by containing an antioxidant in an amount of 0.5 M% or more.

In the present invention, the polyethylene resin includes low, medium,
Any high density polyethylene may be used.

As a copolymer resin mainly composed of ethylene, ethylene-
Examples include propylene copolymer, ethylene-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and the like.

These resins can be used alone or in combination of two or more.

Polybutene is H3CH3 It is expressed as

The weight ratio of polyethylene resin or ethylene-based copolymer resin/polybutene is 65/35 to 90/1.
The content of polybutene must be within the range of 10
If it is less than 35% by weight, there is almost no effect of inhibiting the blooming of the antioxidant, and if it exceeds 35% by weight, the deformation at high temperatures becomes large and the heat resistance decreases.

As antioxidants, phenol group, thioether group,
There are many types that contain phosphorous acid or a combination of these.

It is necessary to add 0.5 parts by weight or more of the antioxidant to 100 parts by weight of the resin, and if it is less than this, no effect of suppressing thermal deterioration will be observed.

The molded article obtained from the resin composition of the present invention can improve heat deformation resistance, chemical resistance, etc. by crosslinking.

Crosslinking methods include heating crosslinking by adding organic peroxide,
Examples include irradiation crosslinking with ionizing radiation.

As an organic peroxide, dicumyl peroxide, 1.3
-bis-(t-butylperoxy-isopropyl)-benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexane, 2゜5-dimethyl-2,5-
Examples include di(t-butylperoxy)-hexyne-3.

When performing irradiation crosslinking, a polyfunctional monomer is added in an amount of 0.5 to 10 mm in order to enable crosslinking at a low radiation dose and to prevent deterioration of the resin and antioxidant due to ionizing radiation. is common.

In the present invention, fillers, colorants, lubricants, flame retardants, etc. that do not impair heat resistance may be added in addition to the above-mentioned components.

[Example] A resin composition was prepared by kneading various components in a roll mill at the mixing ratios shown in Table 1, and the resin composition was mixed at 180°C-10 minutes and 100 kg/cTrl'. A crosslinked sheet was prepared by press molding to a thickness of 5 mm.

The evaluation results for coma are shown in the lower column of Table 1.

The evaluation was based on the following.

Heating deformation rate: 150℃ according to J l5K6723
-1 kg-1 hour.

Aging properties: Tensile properties were measured at the initial stage and after aging at 158°C for 7 days, and changes were determined.

Blooming property: The surface of the sample was visually observed after being left at 60°C for 10 days.

[Effects of the Invention] As explained above, by using the resin composition of the present invention, it is possible to obtain a polyolefin resin molded article that has heat resistance and is free from blooming.

Claims (1)

[Claims] (1) 65 to 90% by weight of polyethylene resin or copolymer resin mainly composed of ethylene and 10 to 35% of polybutene
A heat-resistant polyolefin resin composition characterized in that it contains an antioxidant in an amount of 0.5% by weight or more based on 100 parts by weight of the resin content.