JPH0547221A - Foamed fluorine resin insulated wire - Google Patents

Abstract

(57) [Summary] [Objective] The foamed fluororesin insulating coating formed around the conductor has a foaming degree of 80% or more and a uniform distribution of fine bubbles. [Structure] An insulating coating 2 is extruded on the outer periphery of a conductor 1. This insulating coating 2 is made by foaming a material in which a copolymer of tetrafluoroethylene and hexafluoropropylene or a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether is mixed with an amorphous fluororesin having a glass transition point of 80 to 300 ° C. It is formed by forcing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed fluororesin insulated wire suitable as a signal transmission line for electronic equipment such as a computer.

[0002]

2. Description of the Related Art With the development of electronic devices such as computers and their peripheral devices, it is strongly demanded that the electric wires and cables for signal transmission used in the devices have high performance and high reliability. Is becoming. Above all, there is a strong demand for a thin insulating coating, a high signal transmission rate, no noise or crosstalk, and flame retardancy.

In order to satisfy these requirements, a fluororesin which is essentially flame-retardant and has good electrical characteristics is suitable. Further, by foaming the fluororesin, electrical properties such as a relative dielectric constant are obtained. The characteristics are improved.

Therefore, various methods have been proposed for forming a foamed fluororesin insulating coating. For example, JP-A-59-11340 describes the use of Freon gas as a foaming agent and specific boron nitride as a foaming auxiliary agent, and JP-A-3-8220 discloses a foamed fluororesin. As a material for the insulating coating, a tetrafluoroethylene-hexafluoropropylene copolymer (hereinafter FE
P) or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter referred to as PFA)
Is used.

[0005]

Problems to be Solved by the Invention JP-A-59-1134
Even if the foaming method disclosed in Japanese Unexamined Patent Publication No. 0 or a combination of this method and the material disclosed in Japanese Unexamined Patent Publication (Kokai) No. 3-8220 is used to form a fluororesin insulating coating, the degree of foaming exceeds 80% It is not possible to obtain a very high foam. In particular, when the thickness of the insulating coating is 1 mm or less, it becomes difficult to make the distribution of fine bubbles in the foam layer uniform.

[0006]

In order to solve the above-mentioned problems, the present invention provides a foamed insulating layer formed on the conductor surface of an insulated wire with a glass transition point of 80 to 300 in FEP or PFA.
It was formed by foaming a material mixed with an amorphous fluororesin at ℃.

As the amorphous fluorocarbon resin having a glass transition point of 80 to 300 ° C., a fluorocarbon resin represented by the following (Chemical Formula 1) is used, and particularly, a glass transition point of 150 to 25 is used.
Those in the range of 0 ° C. are preferable in terms of heat resistance and adhesion with a conductor. Here, the glass transition point depends on the ratio of m and n in the formula, and the smaller m / n is, the higher the glass transition point is.
It becomes 0 ° C. The amorphous fluororesin is not limited to one type, and two or more types having different glass transition points may be mixed and used.

[0008]

[Chemical 1]

Examples of the foaming agent include inert gases such as nitrogen, helium, neon, argon and carbon dioxide, hydrocarbons such as methane, propane, butane and pentane, fluorotrichloromethane, difluorodichloromethane, trifluorochloromethane and tetrafluoro. Two or more kinds of blowing agents may be used by selecting from low molecular weight fluorocarbons such as methane, difluorochloromethane, trifluoromethane, trifluorotrichloroethane, and tetrafluorodichloroethane.

In the foaming method, a fluorocarbon resin is uniformly kneaded with a foaming agent, or in the case of a gaseous foaming agent, it is blown into the resin using a pipe or the like. Then, if necessary, inorganic fine powder such as boron nitride, silicon dioxide, titanium dioxide, alumina, zirconium oxide, etc. is added as a foam nucleating agent to adjust and uniformize the bubble diameter, and foaming is performed by a known method.

A non-foaming reinforcing layer of fluororesin, vinyl chloride resin or the like may be provided on the outer periphery of the foamed fluororesin insulating layer.

[0012]

By mixing an amorphous fluorocarbon resin having a glass transition point of 80 to 300 ° C. with FEP or PFA and foaming, an insulating coating having a thin wall and a large number of fine bubbles uniformly distributed is formed.

[0013]

[Example] A glass transition point of 160 in FEP or PFA
C. and 240.degree. C. of amorphous fluororesin were blended in the proportions shown in (Table 1) to prepare a fluororesin material, to which 0.5% by weight of boron nitride was added. Freon-22 was added in the middle of the extruder. Is injected at a pressure of 5 to 6 kg / cm ² G to be uniformly dispersed in the molten resin, and is extruded as an insulating coating 2 having a thickness of 0.2 mm on the outer circumference of a conductor 1 having an outer diameter of 0.26 mmφ shown in FIG. did.

[0014]

[Table 1]

The above-mentioned extrusion conditions use a 20 mm extruder,
L / D = 25, compression ratio = 2.5, groove depth of supply section = 2.
5 mm, groove depth of metering part = 1.0 mm, screw rotation number = 4 rpm, set temperature of each cylinder = 400 ° C, crosshead set temperature = 370 ° C, die set temperature in FEP = 290 ° C, die in PFA Set temperature = 310
C., die inner diameter = 0.38 mm.

From Table 1, the foaming degree is low when FEP or PFA is used alone, but when the amorphous fluorocarbon resin is mixed with FEP or PFA, the foaming degree is 80%.
It turns out to be over%. The foaming degree was calculated from the following formula.

Foaming degree (%) = {1- (ρ / ρ ₀ )} × 100 (ρ: specific gravity of foam, ρ ₀ : specific gravity of non-foam)

[0018]

As is apparent from the above description and (Table), according to the present invention, a mixture of FEP or PFA with an amorphous fluororesin having a predetermined glass transition point is used as a foamed fluororesin material. As a result, the degree of foaming is 8
It is possible to realize an ultra-high-foaming thin-wall insulation coating in which a large number of fine bubbles are uniformly dispersed at 0% or more.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a foamed fluororesin insulated wire according to the present invention.

[Explanation of symbols]

 1 ... conductor, 2 ... insulation coating.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H01B 13/14 B 7244-5G // C08F 214/26 MKQ 9166-4J

Claims (2)

[Claims] 1. An insulated wire in which a foam insulating layer is formed on the surface of a conductor directly or through a fusion layer, wherein the foam insulating layer is a copolymer of tetrafluoroethylene and hexafluoropropylene or tetrafluoroethylene and perfluoro A foamed fluororesin insulated wire, comprising a material in which an amorphous fluororesin having a glass transition point of 80 to 300 ° C. is mixed with a copolymer with an alkyl vinyl ether. 2. The foamed fluororesin insulated wire according to claim 1, wherein the amorphous fluororesin is represented by the following general formula (Formula 1). [Chemical 1]