JPH04355014A - Manufacture of high foaming insulated wire - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a high forming insulated wire whose insulation coating is thin and foaming rate is high. CONSTITUTION:Fine grains of a material whose melting point is higher than that of an insulating resin which can be easily gasified by a gas which can chemically change a material being solid at ordinary temperature and normal pressure into a gaseous material at ordinary temperature and at normal pressure are dispersed into an insulating resin 2. The insulating resin 2 is coated on a conductor 1 and then, the dispersed fine grains are gasified and removed by a gas which can chemically change a material being solid at ordinary temperature and normal pressure into a gaseous material at ordinary temperature and normal pressure so as to produce foamed 4 in the insulating resin.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a highly foamed insulated wire.

0002

[Background Art] Insulated wires used in coaxial cables for signal transmission used in electronic devices such as computers and their peripherals are required to have high-speed signal transmission characteristics and low characteristic impedance. . In recent years, requirements for these properties have become increasingly strict. High speed signal transmission characteristics and low characteristic impedance can be achieved by reducing the thickness of the insulation coating and increasing foaming. Conventionally, extrusion moldable Teflon (tetrafluoroethylene)/hexafluoroethylene copolymer (FEP) and tetrafluoroethylene/perfluoroalkyl vinyl ether have been used to improve the heat resistance of cables and to lower the dielectric constant of the insulation coating material itself. Copolymer (PF
A), tetrafluoroethylene/ethylene copolymer (E
TFE) etc. are used as the insulation coating material. A foamed insulated wire is manufactured by mixing these insulating coating materials with a foaming gas such as chlorofluorocarbon and applying the foamed coating around the core conductor using an extruder.

0003

[Problem to be solved by the invention] However, due to strict demands for higher speed signal transmission characteristics and lower characteristic impedance, the thickness of the insulation coating is becoming thinner and thinner.
When the wall thickness is 0.3 mm or less, it is difficult to stably obtain a foamed coating using conventional methods. This is particularly difficult for highly foamed coatings with a foaming rate of 70% or more.

0004

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present invention has developed a method for manufacturing highly foamed insulated wires that can meet the demand for thinner insulation coatings as a result of intensive studies. It is possible to chemically change a substance that is solid at room temperature and normal pressure into a substance that is gaseous at room temperature and normal pressure.It is made into a conductor by dispersing fine particles of a substance that has a higher melting point than an insulating resin that can be easily vaporized by gas. Covering the insulating resin,
After that, the dispersed fine particles are vaporized and removed using a gas that can chemically change a substance that is solid at room temperature and normal pressure into a substance that is gaseous at room temperature and normal pressure, and pores are created in the insulating resin. This is a method for manufacturing a highly foamed insulated wire, which is characterized by: In the present invention, an insulating resin in which fine particles are dispersed is foamed by a method other than the above and coated on a conductor, and then a substance that is solid at room temperature and pressure is chemically changed to a substance that is gaseous at room temperature and pressure. It is also possible to further improve the porosity within the resin by vaporizing and removing the dispersed fine particles using a gas that can be used to remove the dispersed particles. Also, ClF3 is a gas that can chemically change a substance that is solid at room temperature and pressure into a substance that is gaseous at room temperature and pressure.
(Chlorine trifluoride) is preferred. Furthermore, the fine particles to be dispersed in the insulating resin include Si, Si3 N4, and SiC.
, SiO2, etc. are suitable.

[0005]

[Function] In the production of highly foamed insulated wires that require smaller diameters and thinner walls, the present invention adds a substance that is solid at room temperature and pressure to an insulating resin, and a substance that is gaseous at room temperature and pressure. Fine particles of a substance that can be easily vaporized by a gas that can be chemically changed into a substance and which has a higher melting point than the insulating resin are dispersed, and the core conductor is coated with the insulating resin, and then the above-mentioned By vaporizing and removing dispersed particles with gas and creating pores in the resin, it is possible to manufacture small diameter thin cables that cannot be manufactured by foam extrusion. This makes it possible to improve the foaming rate. To give specific names of substances, the fine particles to be dispersed in the insulating resin include Si, Si3 N4 as mentioned above.
, SiC, SiO2, etc., and these are chemically changed into fluorinated gases at room temperature and pressure by a certain substance, such as ClF3, and are removed from the insulating resin, leaving pores.

[0006]

[Example] Example 1 PFA pellets of 2 mmφ x 2 mml in which 30% by weight of Si fine particles with an average particle diameter of 5 μmφ were dispersed were melted and kneaded using a screw extruder and extruded through a crosshead at a linear speed of 1 m. 0.1m running at /min
A core conductor with a wire diameter of mφ was covered with a thickness of 0.085 mm for 10,000 m (see FIG. 1). Of course, with this wall thickness it is not possible to carry out foam extrusion. The produced insulated wire was then subjected to vaporization treatment of Si fine particles in a vacuum processing apparatus. In this example, batch processing is performed, but it goes without saying that continuous processing after extrusion coating is also possible. In the vaporization process, after setting the insulated wire bobbin in the device and making it possible to run the wire, a vacuum is drawn and maintained at 1 x 10-5 Torr to remove atmospheric components in the atmosphere, and then purged with high-purity nitrogen to atmospheric pressure. do. after that,
ClF3 gas diluted to 1% with nitrogen at 0.3 m/m
The solution was sprayed over a 1 m length of an insulated wire running in the air so as to come in contact with the insulated wire. After the entire length was vaporized, vacuum was drawn again to remove the ClF3 gas, and the pressure was returned to atmospheric pressure. Through this vaporization treatment, the Si fine particles dispersed within the insulating coating could be fluorinated and removed (see FIG. 2). The foaming rate of the manufactured insulated wire was measured by the density method and was 65%. In addition, when the concentration of ClF3 gas was increased to 30% in the vaporization process, vaporization proceeded even faster, and the coating resin was softened by the generated heat, and pores grew due to the expansion of the generated gas.
The foaming rate improved to 80%.

Example 2 20% by weight of Si3N4 fine particles with an average particle diameter of 4 μmφ
The dispersed PFA pellets of 1 mmφ x 1 mml are melted using a screw extruder, kneaded with Freon 22, and foamed and extruded around a core wire conductor with a wire diameter of 0.24 mmφ, resulting in a foaming rate of 75% and an outer diameter. 1mm
A foam insulated wire was manufactured (see Figure 3). The manufactured insulated wire was treated with Si3N4 using ClF3 gas diluted to 1% with nitrogen in a vacuum processing apparatus as in Example 1.
The fine particles were vaporized. Through this vaporization treatment, the Si3N4 fine particles dispersed within the insulating coating could be fluorinated and removed (see FIG. 4). The foaming rate of the manufactured insulated wire was measured by the density method and was 90.
I was able to get %.

[0008]

[Effects of the Invention] As described above, according to the present invention,
It makes it possible to manufacture thin-diameter, thin-walled foamed insulated wires that cannot be manufactured by foaming extrusion, and it also makes it possible to further improve the foaming rate of conventionally sized foamed insulated wires, resulting in remarkable industrial effects. It is something to play.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an insulated wire before vaporization treatment in Example 1.

FIG. 2 is a cross-sectional view of the insulated wire after vaporization treatment in Example 1.

FIG. 3 is a cross-sectional view of an insulated wire before vaporization treatment in Example 2.

FIG. 4 is a cross-sectional view of an insulated wire after vaporization treatment in Example 2.

[Explanation of symbols]

1 Core conductor 2 PFA 3 Si particles 4 Pores due to vaporization treatment 5 Pores in extrusion 6　Si3　N4　particles

Claims (4)

[Claims] Claim 1: The insulating resin contains a substance that has a higher melting point than the insulating resin and can be easily vaporized by a gas that can chemically change a substance that is solid at normal temperature and normal pressure into a substance that is gaseous at normal temperature and normal pressure. The conductor is coated with the insulating resin, and then dispersed with a gas that can chemically change a substance that is solid at room temperature and pressure into a gaseous substance at room temperature and pressure. 1. A method for producing a highly foamed insulated wire, the method comprising: vaporizing and removing fine particles caused by foaming, and creating pores in an insulating resin. 2. After foaming the insulating resin in which fine particles are dispersed by a method other than the above and covering the conductor, the insulating resin is heated at room temperature.
A claim characterized by further improving the porosity within the resin by vaporizing and removing dispersed fine particles with a gas that can chemically change a substance that is solid at normal pressure into a substance that is gaseous at normal temperature and pressure. Item 1. A method for producing a highly foamed insulated wire according to item 1. [Claim 3] A substance that is solid at normal temperature and normal pressure is
2. The method of manufacturing a highly foamed insulated wire according to claim 1, wherein the gas that can be chemically changed into a substance that is a gas at normal pressure is ClF3. 4. The fine particles dispersed in the insulating resin are Si
, Si3 N4 , SiC or SiO2 , the method for manufacturing a highly foamed insulated wire according to claim 1 .