JPH0724897A - Manufacture of electric insulator - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing an electric insulator of fluorine rubber having excellent extrusion processability, no contact of molded forms after extrusion molding, and excellent extrusion external appearance. CONSTITUTION:10-less than 100 pts.wt. of fluorine resin powder having a particle size of 100mum or less is mixed with 100 pts.wt. of fluorine rubber at a temperature of a melting point or lower of the resin, and extrusion molded at a temperature of the melting point or higher of the resin.

Description

Detailed Description of the Invention

[0001]

The present invention has excellent extrusion processability,
The present invention relates to a method for producing a fluororubber-based electrical insulator in which molded products do not adhere to each other after extrusion molding.

[0002]

2. Description of the Related Art Fluorine rubber is used for gaskets, packings, hoses and the like by taking advantage of its excellent heat resistance, oil resistance and chemical resistance. However, when such a fluororubber is used for an electric wire or a heat shrinkable tube, the fluororubber alone has a weak mechanical strength and cannot be used as it is. Therefore, for example, as disclosed in Japanese Patent Publication No. 2-17341, a crystalline polymer is added to fluororubber to improve the mechanical properties of fluororubber. And as the crystalline polymer, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-
A crystalline fluororesin such as a hexafluoropropylene copolymer or a polyvinylidene fluoride-fluoroolefin copolymer is used.

[0003]

When extruding a fluororubber mixed with such a fluororesin, there is a problem that the compact immediately after the extrusion is adhered. When a fluororubber mixed with such a fluororesin is used for the wire coating, the coating of the wires wound on the drum after extrusion will stick to each other, and if the adhesion is severe, the coating will break when the wire is pulled out. I will end up. Further, if the electric wires bundled after being made into a product are in close contact with each other, it is difficult to pull out the electric wires when they are used, and the workability becomes extremely poor.

In order to solve such a problem, powder of talc or the like has been hitherto dusted or silicone oil or the like has been applied to the surface. However, such a measure does not look good as an electric wire and has a commercial value. To lower.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and provides a method for producing a fluororubber-based electric insulator which has excellent extrusion processability and does not adhere to each other after extrusion molding. The characteristic is that 100 parts by weight of fluororubber are mixed with 10 parts by weight or more and less than 100 parts by weight of fluororesin powder having a particle size of 100 μm or less at a temperature not higher than the melting point of the fluororesin, and a temperature not lower than the melting point of the fluororesin. It is in extrusion molding.

[0006]

When the fluororubber and the fluororesin are mixed, the temperature is usually higher than the melting point of the fluororesin, but in the present invention, the temperature is lower than the melting point of the fluororesin.
Use powder of 100 μm or less. When the mixture mixed by such a method is extrusion-molded at a temperature higher than the melting point of the fluororesin, it is mysterious that there is no adhesion between the coatings after the extrusion-molding, and the extrusion-processability is very good. Found. It may be because the mixing at low temperature reduces the tackiness of the fluororubber, but the reason is not clear.

As the fluororubber to be used, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-propylene copolymer, etc. Is used.

Examples of the fluororesin include polyvinylidene fluoride, polyvinylidene fluoride-fluoroolefin copolymer, ethylene-tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-chlorotrifluoroethylene. A copolymer, a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, a polytetrafluoroethylene or the like is used.

It is necessary that the particle size of the fluororesin is 100 μm or less, and if it is larger than this, the appearance of the molded product is deteriorated.
Further, the addition amount of the fluororesin must be 10 parts by weight or more and less than 100 parts by weight with respect to 100 parts by weight of the fluororubber. Ten
If it is less than 100 parts by weight, the adhesion of the molded product cannot be prevented, and if it is more than 100 parts by weight, the low temperature characteristics deteriorate, and it cannot be used as an electrical insulator. The extrusion temperature of the molded body needs to be equal to or higher than the melting point of the fluororesin. Extrusion with a good appearance cannot be performed at a temperature below the melting point of the fluororesin.

The fluororubber molding of the present invention may contain inorganic fillers and compounding agents which are usually added to fluororubbers. For example, talc, clay, calcium carbonate, silica, magnesium oxide, zinc oxide, lead oxide,
Examples include carbon, a cross-linking agent, and a cross-linking accelerator.

[0011]

【Example】

Examples 1 to 5: The fluororubber composition shown in Table 1 was prepared at 60 ° C.
The mixture was roll-kneaded for 15 minutes, and extrusion-coated with a thickness of 0.5 mm on a 0.8 mmφ tin-plated annealed copper wire. The coated electric wire after extrusion molding was wound on a drum and the adhesion of the electric wire coating was evaluated. The extruded coated electric wire was irradiated with 10 Mrad electron beam by a 2 MeV electron beam accelerator. This electric wire was placed in a low temperature tank and wound around a mandrel having a diameter equal to the outer diameter of the electric wire, and the temperature at which cracks occurred was examined. All of these results Examples 1 to 5
The appearance was good and extrusion was possible and there was no adhesion. The low temperature characteristics were also good.

Comparative Examples 1 to 4 The fluororubber compositions shown in Table 1 were kneaded at 60 ° C. or 160 ° C., and coated electric wires were prepared and evaluated in the same manner as in Examples. Comparative Example 1 was kneaded at a temperature equal to or higher than the melting point of the fluororesin, and the electric wire coatings were in close contact with each other, and the appearance was worse than that of Example 3 in which kneading was performed at a low temperature.
In Comparative Example 2, a fluororesin having a particle diameter of 500 μm was used, and the appearance of the extruded electric wire coating was very poor. Comparative Example 3 was poor in low-temperature characteristics when 100 parts by weight or more of the fluororesin was added. Further, as in Comparative Example 4, when the extrusion temperature was lower than the melting point of the fluororesin, the extrusion appearance was poor.

[0013]

[Table 1]

[0014]

As described above, according to the method for producing an electric insulator of the present invention, a fluororubber-based electric insulator having a good extruded appearance without adhesion between the extruded molded articles is obtained. be able to.

Claims (2)

[Claims] 1. A particle size of 100 per 100 parts by weight of fluororubber.
A method for producing an electrical insulator, which comprises mixing 10 parts by weight or more and less than 100 parts by weight of a fluororesin powder having a size of μm or less at a temperature not higher than the melting point of the fluororesin and extruding at a temperature not lower than the melting point of the fluororesin. 2. The method for producing an electrical insulator according to claim 1, wherein the fluororesin is polyvinylidene fluoride or a vinylidene fluoride-fluoroolefin copolymer.