JPH03230417A - Polytetrafluoroethylene resin coated electric wire - Google Patents

Abstract

PURPOSE:To identify even from a cross section by providing an insulating coated layer with polytetrafluoroethylene resin(PTFE) as a primary component on the outside of a conductor, and by dividing the layer into several parts in a radial form in the direction of the radius of the conductor, so as to obtain different colors. CONSTITUTION:An insulating coated layer 18 with PTFE as a primary component is pressurized and extruded on the outside of a conductor 2. The coated layer 18 is divided into several parts 18a, 18b, 18c in the circumferential direction or in the radial direction of the radius of a PTFE cable 11, and any two divisions have different colors, while the thickness of the insulating coated layer of each division is almost equal. A line condition can thus be obtained, where by seeing not only the surface of a finished product, but also its cross sectional surface, identification is possible. Since the thickness of the coating for each color is the same, inter-coating adhesion is good.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polytetrafluoroethylene resin-coated electric wire in which the outside of a conductor is coated with polytetrafluoroethylene resin.

As is well known, tetrafluoroethylene resin (hereinafter abbreviated as PTFE) is a material with excellent chemical stability, heat resistance, electrical properties, etc. However, this PTFE has problems in its moldability and does not have fluidity even when heated above its melting temperature, so it cannot be used as an insulator for electric cables or as a coating layer for long filaments. In this case, it is difficult to apply the melt extrusion coating method as with other resin insulating materials. For this reason, as shown in Japanese Unexamined Patent Publication No. 52-72765, a method for continuously coating a linear conductor with PTFE is to form a preformed body using tetrafluoroethylene resin powder in advance, and A method is known in which the material is loaded into the cylinder of a ram extruder and then extruded under pressure.

By the way, recently, electric wires coated with PTFE have come into widespread use. Examples include wiring cables for electronic communication equipment, control cables in power plants, and coaxial cables. A large number of these cables are often used at the same time, and therefore it is necessary to identify cables that are adjacent to each other.

As identification means, it is well known to (1) make the entire sheathing of each cable different from each other, and (2) print a symbol on the surface of each cable sheath, but in the former (1) method, the number of colors is different. Furthermore, the extrusion mechanism of the extrusion molding machine must be cleaned every time the color changes, and in the latter method (2), there is a risk that the printing ink will disappear over time. .

As a means of compensating for these drawbacks, a method has recently been proposed in which, when melt-extruding a cable sheath, simultaneously extrusion-molding identification lines of different colors is formed in a spiral or linear shape.

However, this method is applicable only to plastic materials that can be melt-extruded, and fluorocarbon resin, which is the subject of this invention, cannot be melt-extruded.

Furthermore, according to the melt extrusion method, the thickness of the different colored identification lines is formed only very thinly on the surface of the cable sheath. For this reason, it is difficult to identify this when looking at the cross section of the obtained electric wire cable.

The present invention has been made to advantageously eliminate the above-mentioned drawbacks, and aims to provide a polytetrafluoroethylene resin coated electric wire that can be easily distinguished from other electric wire cables from a cross section of the electric wire cable. purpose.

The gist of the invention is that an insulating coating layer 18 mainly composed of polytetrafluoroethylene resin is extruded on the outside of the conductor 2 under pressure, and this insulating coating layer extends radially in the radial direction of the conductor 2. A tetrafluoroethylene resin coating characterized by being divided into a plurality of sections, any two sections having different colors, and the thickness of the insulation coating layer of each section being approximately equal. It's an electric wire.

FIG. 1 shows an example of a coating apparatus for producing a polytetrafluoroethylene resin-coated wire according to the present invention. An embodiment of the present invention will be described in detail based on this figure.

A linear conductor 2 is sent out from a supply reel 1.

This conductor 2 is first introduced into a ram extruder 3.

This ram type extruder 3 has a die 5 at the tip of the cylinder 4, and a plunger 6 from the base end of the cylinder 4.
In particular, the plunger 6 is provided with a hole 6b that extends along the center line of the plunger a and opens at the center of the inner surface of the plunger 6.
is guided into the cylinder 4 through the hole 6b.

Inside the cylinder 4, a preform 7 made of a mixture containing PTFE as a main component is loaded as a coating material.

The preformed body 7 is made of a mixture of powdered PTFE and a lubricant for giving moldability to this PTFE.
As shown in FIG. 2, it is formed into a cylindrical shape having a through hole 7a along the center line. The PTFE used for this preform 7 has a particle size of 450 to 550 nm.
It is preferable that it contains a certain amount of pigment, and as described later, it contains some pigment to give it the desired color.

Moreover, naphtha, petroleum, etc. are suitable as the lubricant.

The mixing ratio of this lubricant to 100 parts by weight of PTFE is preferably 15 to 25 parts by weight.

A pressure molding method can be applied to obtain the preformed body 7 by molding the above mixture of PTFE and lubricant. in this case,
The molding pressure is preferably 10 kg/c4 or less; if it exceeds this, the force required during extrusion by the extruder 3 will increase, which is disadvantageous.

Further, in this example, as shown in FIG. 2, the preform 7 is divided into three portions 7b7c and 7d by three surfaces extending radially outward from the through hole 7a, and each portion 7b .

7c and 7d are made of a mixture of different colors.

In order to obtain such a preform 7, for example, as shown in FIG.
, 10d are fixed to the partition member 10, which is removably arranged to form a partition plate 10b.

Fill the parts divided by 10c and 10d with a mixture having the desired color, and then gently insert the partition member 1.
A preformed body is obtained by removing 0 and press-molding.

In the extruder 3 loaded with the preformed body 7 as described above,
The conductor 2 introduced from the hole 6b of the plunger 6 passes through the through hole 7a of the preform 7, and is pulled out from the die 5 and arranged. To coat the conductor 2 with the mixture, the conductor 2
while pulling out the plunger 6 toward the die 5 side at a constant speed.
The preform 7 is pressed and the mixture is extruded with an outer diameter limited by the diameter of the die 5. Thereby, the conductor 2 is coated with a mixture of PTFE and lubricant.

The coated wire 11 formed as described above is guided by guide rollers 12, 12, 12 and passed through a heated atmosphere, for example, three drying ovens 13, 1313, to heat the lubricant in the coating layer. Remove. The temperature of this drying oven is usually about 200''C.

The coated wire 11 that has passed through the drying furnace 13 is then led to another heating atmosphere, for example, the firing furnace 14, where PTFH is fired.The temperature required for firing is higher than the melting temperature of PTFE, and is usually 360 to 450°C. The degree is appropriate. The PTFE that forms the coating layer of the coated electric wire 11 by firing has powder particles closely bonded to form a uniform coating layer, and by cooling this, a PTFE coated electric wire as a product can be obtained.

The coated electric wire 11 that has passed through the firing furnace 14 is wound up by a winding machine 17 through a capstan 15 and a guide roller 16 for take-up.

Therefore, PT manufactured by the above manufacturing method
The FE-coated wire 11 is made of PTFE, which is an excellent insulating material, and has excellent chemical safety, heat resistance, and electrical properties. Furthermore, in the above example, the preform 7 is made of a mixture of the three colors shown in FIG. Layer 18 is circumferential, i.e. PTF
A plurality of portions 18a radially extend in the radial direction of the E electric wire 11.
, 18b, and 18c, any two sections have different colors, and the thickness of the insulating coating layer in each section is approximately equal.

According to this invention, an insulating coating layer 18 mainly composed of tetrafluoroethylene resin is extruded on the outside of the conductor 2 under pressure, and a plurality of insulating coating layers are arranged radially in the radial direction of the conductor 2. (1)
Since the mixture of each color is coated on the filament with approximately the same thickness, it is possible to obtain a filament that can be identified not only by looking at the surface of the finished product but also by looking at its cross section. (2) Since the thickness of each colored coating is the same, the adhesion between each coating is extremely good. (3) In the melt extrusion method, the coating
To create more colors, it is necessary to install as many extruders as there are colors or as many molten resin channels as there are colors in the crosshead.In addition, it is necessary to clean the inside of the crosshead each time the color is changed. However, according to the present invention, by changing the combination of colors of the preform, it is possible to obtain multicolored coatings by using a conventional ram extruder as is.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for manufacturing the polytetrafluoroethylene resin-coated wire of the present invention, and FIG. 2 is a preformed body used for manufacturing the polytetrafluoroethylene resin-coated wire of the present invention. FIG. 3 is a partially cutaway perspective view showing a mold for molding the preform shown in FIG. 2, and FIG. FIG. 2 is a perspective view showing an ethylene-containing resin-coated electric wire. 2 is a conductor, 3 is a ram type extruder, 4 is a cylinder, 5 is a die, 6 is a plunger, 6b is a hole, 7 is a preform, 7a
1 is a through hole, 7b, 7c, and 7d are divided portions of the preform, 11 is a polytetrafluoroethylene resin-coated electric wire, 13 is a drying oven, 14 is a firing oven, 18 is an insulating coating layer, 18a, 18
b and 18c are parts of the insulation coating layer with different colors. Figure 2 Figure 3 Figure 4 Figure 1

Claims (1)

[Claims] An insulating coating layer (18) mainly composed of tetrafluoroethylene resin is extruded on the outside of the conductor (2) under pressure, and this insulating coating layer has a plurality of layers arranged radially in the radial direction of the conductor (2). A polytetrafluoroethylene resin-coated electric wire characterized in that it is divided into sections, any two sections have different colors, and the thickness of the insulation coating layer of each section is approximately equal. .