JPH01117209A - Formation of high forming fluorine resin insulating coverage - Google Patents

Abstract

PURPOSE:To improve the adhesive performance of an insulating coverage by dispersing a foaming agent in a fused fluorinated resin evenly, then extruding it to obtain a linear high foaming substance, and adding longitudinally or winding the linear high foaming substance at the periphery of a conductor. CONSTITUTION:Linear high foaming substances 2 are wound on a conductor 1, and a guard winding 3 is furnished at the outer side of them. A linear high foaming substance 2 with the outer diameter 0.5mm and the foaming rate 73% is obtained by feeding tetrafluoroethylene-perfluoroalkylvinylether copolymer(PFA) 100 pts.wt. to which boron nitride 0.5wt.% is added, from a hopper of an extruding machine, pouring Freon-22 at the pressure 7-8kg/cm<2>G at the middle part of the extruding machine to disperse evenly in the fused resin, and then extruding it. Numerous lines of the resultant foaming substance 2 are wound attaching longitudinally at the periphery of the conductor 1 with the outer diameter 0.5mm, over which a polytetrafluoroethylene tape is wound as a guard winding 3 to form a high foaming insulating coverage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing a foamed fluororesin insulated wire suitable for application to signal transmission lines of electronic devices such as computers.

[Background Art] With the development of electronic devices such as computers and their peripheral devices, the electric wires and wires used for signal transmission in the devices have increased.
Cables are also required to have higher performance and reliability.In particular, cables with thin insulation coatings, high signal transmission speeds, no noise or crosstalk (and flame retardant) are becoming increasingly required. There is a strong demand that

To meet these requirements, fluororesin is suitable because it is inherently flame retardant and has good electrical properties, and foaming this resin leads to improvements in electrical properties such as dielectric constant. .

[Problems to be Solved by the Invention] In recent years, it has been desired to further increase the foaming degree of the fluororesin insulation coating to improve its performance. However, when the degree of foaming is increased to three times (67%) or more, the conductor and the insulating coating become separated, resulting in a problem that the adhesion is greatly reduced. In particular, this tendency becomes more pronounced as the insulation coating becomes thinner.

The present invention has been made based on the above, and aims to provide a method for forming a highly foamed fluororesin insulation coating that can improve the adhesion between a conductor and an insulation coating.

[Means for solving the problem] A method for forming a highly foamed fluororesin insulation coating involves introducing a hot melt extrudable fluororesin and a gas blowing agent or a liquid blowing agent into an extruder, and adding the blowing agent into the molten fluororesin. The method is characterized in that it is uniformly dispersed and then extruded to obtain a linear highly foamed body, and this linear highly foamed body is vertically attached or wrapped around the outer periphery of the conductor.

In the present invention, as the hot melt extrudable fluororesin, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (r'FA), ethylene-
Examples include tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, and vinylidene fluoride.

The blowing agent used in the present invention is normally gaseous or liquid, and includes inert gases such as nitrogen, helium, neon, and argon, hydrocarbons such as methane, propane, butane, and pentane, dichlorodifluoromethane, and dichloromonocarbons. Examples include halicenated fluorinated hydrocarbons such as fluoromethane, monochlorodifluoromethane, trichloromonofluoromethane, and trichlorotrifluoromethane.

The method of adding the foaming agent is to impregnate the resin with the foaming agent in advance,
Alternatively, a blowing agent may be injected into the extruder.

In the present invention, a foam nucleating agent may be used to facilitate adjustment of the cell diameter and formation of uniform cells. Examples of the foam nucleating agent include boron nitride, silicon oxide, titanium oxide, alumina oxide, Examples include zirconium.

[Embodiment 1 of the Invention Embodiment 1 FIG. 1 is an explanatory cross-sectional view of a highly foamed insulated wire according to the present invention, where l is a conductor, 2 is a linear highly foamed body, and 3 is a presser winding.

PFA (manufactured by Daikin Industries, product name: NEOFLON PF)
A AP-210) 0.5% by weight of boron nitride added to 100 parts was fed from the hopper of the extruder, and Freon-22 (trade name of DuPont) was added at 7 to 7% in the middle of the extruder. Injected at a pressure of 8 kg/cm"G to uniformly disperse in the molten resin and then extruded, with an outer diameter of 0.5 mmφ,
A highly foamed linear body with a degree of foaming of 73% was obtained. A large number of this linear high-foaming material 2 is vertically wound around the outer circumference of a conductor l with an outer diameter of 0.5 mmφ, and a polytetrafluoroethylene tube with a thickness of 0.1 mm is wrapped around the outer circumference as a presser winding 3. An insulating coating was formed.

The extrusion conditions for the linear highly foamed material are as follows: using a 20 mm extruder, L/D = 25, compression ratio = 2.5, groove depth of the feeding section =
2.5mm, groove depth of measuring part = l, Omm, screw rotation speed = 4rpm, set temperature of each part of cylinder = 400℃
, crosshead setting temperature = 370℃, die setting temperature =
The temperature was 320° C., and the die inner diameter was 0.5 mm.

Comparative example PFA (manufactured by Daikin Industries, Ltd., product name: Neoflon P
FA AP-210) 0.5% by weight of boron nitride added to 100 parts by weight was supplied from the hopper of the extruder, and 7 to 8 kg of Freon-22 (trade name of DuPont) was added in the middle of the extruder. /cm"G pressure to uniformly disperse it in the molten resin, and then extrude it around the outer circumference of a conductor with an outer diameter of 0.5 mm to form a highly foamed insulating liquid with a foaming degree of 80% and a thickness of 0.4 mm. did.

Table 1 shows the results of evaluating the conductor adhesion and degree of foaming of the highly foamed insulated wires of Examples and Comparative Examples.

The conductor adhesion was evaluated by holding 1 m of insulated wire vertically and measuring the pull-out force of the conductor, and the degree of foaming was determined from the following formula.

Foaming degree - (l - (ρ/ρ. Month x lOO [%ko (ρ: specific gravity of foam, ρ.: specific gravity of non-foamed body) Table 1 As is clear from Table 1, the insulated wire of the example The pulling force was as high as 20 g/m, whereas the comparative example insulated wire had a gap or a groove between the conductor and the insulation coating, so both were completely separated, so the pulling force was 0. there were.

"Effects of the Invention" As explained above, according to the present invention, the adhesion of a thin, highly foamed fluororesin insulation coating can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of an example of a highly foamed insulated wire manufactured according to the present invention. l; Conductor 2: Linear high foam 3: Presser winding Figure 1

Claims (1)

[Claims] (1) Introduce a hot melt extrudable fluororesin and a gas blowing agent or a liquid blowing agent into an extruder, uniformly disperse the blowing agent in the molten fluororesin, and then extrude to obtain a linear highly foamed body. A method for forming a highly foamed fluororesin insulation coating, which comprises vertically attaching or wrapping a linear highly foamed material around the outer periphery of a conductor.