JPS61204247A - Polyolefin composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition having excellent heat-resistance and voltage-resistance and suitable for the distributor cap and rotor of an automobile, by adding a small amount of a foaming agent to a composition composed of a polyolefin and silica at a specific ratio. CONSTITUTION:The objective composition is produced by compounding (A) 100pts.wt. of a composition composed of (i) 95-40wt%, preferably 90-40% polyolefin (preferably propylene polymer) and (ii) 5-60%, preferably 10-60% silica (preferably having an average particle diameter of 1-50mu) with (B) 0.05-0.5pts. of a foaming agent (e.g. azodicarbonamide).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a voltage-resistant composition containing a polyolefin, an inorganic filler, and a blowing agent, and in particular, a composition containing silica and a blowing agent for automobile distributor caps and rotors. The present invention relates to a polyolefin composition with good heat resistance and voltage resistance suitable for various uses.

Conventional technology Attempts have been made to add arc resistance and tracking resistance to polyester resins, phenolic resins, polyolefin resins, etc., by adding inorganic fillers to them for use as structural materials and insulating materials for electrical components such as automobiles. . However, the performance required of modern automotive die repeater caps and rotors has increased due to higher voltage resistance and higher voltage applied to accommodate new pollution prevention technology and higher engine performance. Durability against heat is required. For this purpose, large amounts of inorganic fillers are added or the wall thickness of the molded product is made thicker, but this creates voids inside the molded product and causes sink marks on the surface of the molded product. However, the voltage resistance was rather deteriorated. Japanese Patent Laid-Open No. 53-50251 describes a technology for foam molding to prevent the occurrence of cracks and sink marks in molded products by adding inorganic fillers or increasing the wall thickness of the molded product.
No., JP-A-59-20533, JP-A-59-2293
No. 6, etc., but none of these techniques has been recognized or obtained with good voltage resistance and heat resistance suitable for use in automobile distributor caps and rotors.

Problems to be Solved by the Invention The present invention solves the above-mentioned problems, that is, prevents the generation of voids inside the molded product when manufacturing the molded product from a polyolefin composition containing an inorganic filler, and prevents sink marks and scratches on the surface of the molded product. The object of the present invention is to provide a polyolefin composition for manufacturing automotive distributor caps and rotors that has good voltage resistance and heat resistance and prevents the occurrence of such occurrence.

The present invention has been completed by discovering a polyolefin composition suitable for automotive distributor caps and rotors that can prevent voids inside molded products and greatly improve voltage resistance and heat resistance.

That is, the present invention provides a voltage-resistant polyolefin composition tt#O consisting of 100 parts by weight of a composition containing 95 to 40% by weight of polyolefin, 5 to 60% by weight of silica, and 0.05 to 0.5 parts by weight of a blowing agent. It is a thing.

The configuration of the present invention will be explained in detail below.

Polyolefins used in the present invention include high-, medium-, and low-pressure polyethylene, polypropylene, polymers such as polybutene-1, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-α- Olefin elastomers such as olefin copolymers, one of these polymers and elastomers
A species or a mixture of two or more species. Among these polymers, propylene-based polymers such as polypropylene, propylene-ethylene random or block copolymers, and propylene-1-butene copolymers are particularly effective; It is preferable to use 'l? Ni: It is preferable to use it in a range of 90 to 40%. In addition, modified polyolefin chlorinated polyethylene, SIR is added to the above olefin resin.

Polyimbutylene, polybutadiene, etc. may be added as a modifier. Other colorants, nucleating agents, anti-aging agents, ultraviolet absorbers, flame retardants, crosslinking aids, foaming aids,
Additives such as lubricants may also be added.

The silica used in the composition of the present invention may be either mechanically pulverized naturally occurring quartz or the like, or synthetic silica. The average particle diameter is 1 to 50 μm, and the amount added is 5 to 60% by weight, particularly preferably 10 to 60% by weight, based on the polyolefin. If it is more than 60% by weight, the moldability will be poor, and if it is less than 10% by weight, the heat resistance and voltage resistance will be poor.

The blowing agent used in the present invention is preferably a thermally decomposable blowing agent that decomposes when heated to relatively rapidly generate gas, such as azodicarbonamide, hydradicarbonamide, dinitron pentametherenetetramine, P, P/-oxybis It is a mixture of 11 or 2 or more types of benzenesulfonyl hydrazide and the like. The amount of the blowing agent can be selected depending on the desired expansion ratio of the foam, but in the foam of the present invention, it is 0.0 parts by weight per 100 parts by weight of the polyolefin resin composition.
It is preferable to add 5 to 0.5 parts by weight in order to exhibit voltage resistance and heat resistance.

In the present invention, the polyolefin is mixed with silica, a blowing agent, and other additives depending on the required IC, and then granulated using various extruders. Of course, this step requires granulation at a resin temperature that is about 20-50°C lower than the decomposition temperature of the blowing agent. A molded article can be molded from the obtained pellet by injection molding, extrusion molding, etc., but it may also be directly molded from a mixture of each component. For foam molding, either the masterbatch method or the triblend method may be used.

Effects of the Invention Molded articles made from the polyolefin composition of the present invention have good voltage resistance and heat resistance, and can be used in applications requiring high voltage resistance, such as dies, IJ computer caps, and four-piece caps.

Examples Examples of the present invention are shown below. The test method in the examples is as follows.

1] Measurement of withstand voltage (promotion): A test piece with a thickness of 12 saa was subjected to a frequency of 700 a7s and a voltage of 25 KV.

Measured at a temperature of 100℃ 2) Heat resistance 2ls'l'MD-648(
6.4% thick test piece, thermal degradation temperature (nDr) measured at 264 psi) Examples 1-5, Comparative Examples 1-7 Polypropylene (MI:20) and silica (average particle size 2
To 100 parts by weight of a mixture consisting of After melt mixing at ~200°C, it was granulated.

The resulting nine pellets were injected into a cylinder at a temperature of 250°C and an injection pressure of 6
A test piece was molded under injection conditions of 0.0 kg and 7 m', and the withstand voltage and
Heat resistance was measured. The results are shown in Table 1 below.

For comparison, similar evaluations were conducted without using silica or foaming agent gold, and with other inorganic fillers, and the results are also listed in Table 1.

From this table, it can be seen that if only polyolefin was used, electricity would be applied in just one hour, but the presence of silica and a blowing agent significantly improves the electrical resistance and heat resistance.

Table 1

Claims (1)

[Claims] 100 parts by weight of a composition of 95-40% by weight of polyolefin and 5-60% by weight of silica and 0.05-0.5% blowing agent
A voltage-resistant polyolefin composition, characterized in that it is made by blending parts by weight.