JP2677844B2 - Method of forming connection part of rubber / plastic insulation cable - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a mold joint of a rubber / plastic insulated cable.

(Prior Art) Conventionally, at the connection portion of a rubber / plastic insulated cable, a rubber / plastic tape that can be fused by heating is wound around the conductor connection portion, or a resin composition is injected into a mold. After forming the reinforcing insulator by the method described above, a method is adopted in which a pressing tape is applied to the outer periphery of the reinforcing insulator to heat the insulating body so that the reinforcing insulator is crosslinked and integrated with the cable insulator. Since this holding tape has the purpose of pressing the reinforcing insulator from the outside to prevent deformation during heating and maintaining its shape, it has a smaller expansion coefficient than that of the material forming the reinforcing insulator and has a tensile strength. Properties such as high mechanical strength and excellent heat resistance are required, and Kapton tape (a product name of polyimide tape manufactured by DuPont, USA) has been widely used.

(Problems to be Solved by the Invention) However, since such a conventional pressing tape has low air permeability, it is used as air entrapped during the winding of the rubber / plastic tape, or as a decomposition residue of the cross-linking agent such as dicumyl peroxide. There is a problem in that the generated methane gas and water vapor cannot be degassed, and voids occur in the insulator, resulting in a marked decrease in insulation performance.

For this reason, it has been proposed to use a fluororesin tape or the like having gas permeability, but these have insufficient mechanical strength and the like, so that a holding tape with high strength must be wound around the outermost periphery. The drawback is that it does not happen.

In view of the above points, the present invention has an object to provide a method for forming a rubber / plastic insulated cable connection portion in which generation of voids is extremely small by using a holding tape having gas permeability and mechanical strength. And

(Means for Solving the Problems) That is, according to the first invention of the present application, as shown in the drawings, a rubber / plastic tape which can be fused by heating is wound around the connecting portion 1 of the rubber / plastic insulating cable, or The method is characterized in that a reinforcing insulator 2 is formed by a method such as injecting a resin composition into a mold, a pressing winding 3 of an aromatic polyamide resin tape is formed on the outer periphery of the reinforcing insulator 2, and then heating is performed. The present invention relates to a method of forming a connection portion of a rubber / plastic insulated cable.

1st invention of this application WHEREIN: By using an aromatic polyamide resin tape as a holding tape wound around the outer periphery of a reinforced insulator, various characteristics required as a holding tape, ie, mechanical strengths, such as tensile strength, are large, Since it retains good properties such as excellent heat resistance and has a large air permeability and sufficient deaeration, it is possible to extremely reduce the occurrence of voids in the insulator. Since it has strength that can be used as, it does not require a separate holding tape.

The reinforced insulator in the first invention of the present application is a rubber that can be fused by heating, such as an uncrosslinked polyolefin tape containing a crosslinker or a self-fusing ethylene-propylene rubber tape on the connection portion, as in the conventional method. It can be formed by winding a plastic tape or molding a resin containing a crosslinking agent with a mold. At this time,
The material used should be of the same quality as the cable insulation.

The aromatic polyamide resin tape according to the first invention of the present application preferably has a tensile strength of about 250 kg / mm ² or more, heat resistance of about 200 ° C., and gas permeability. Specifically, Kevlar cloth tape (a product manufactured by DuPont) Name) etc. can be used. This tape is wound directly on the reinforced insulator or via a release tape. As the release tape, a general one such as a fluororesin tape such as Teflon tape can be used.

After that, the whole is heated by a band heater, infrared heating or the like to heat-bond the reinforcing insulator or crosslink. The decomposed gas of the cross-linking agent generated at this time, the remaining air, and the like pass through the pressing member 3 and are released to the outside, so that they do not remain as voids in the reinforcing insulator.

In addition, a second invention of the present application is that, on the outer periphery of a reinforcing insulator provided on a conductor connecting portion of a rubber / plastic insulated cable, a tape in which silicone rubber is coated on one side of an aromatic polyamide resin tape is provided on the silicone rubber side. The present invention relates to a method for forming a connecting portion of a rubber / plastic insulated cable, which comprises applying pressure to the reinforcing insulating material and heating the same.

The second invention of the present application uses, in the invention of the first invention of the present application, a presser roll in which one side of the aromatic polyamide resin tape is coated with silicone rubber. Therefore, a release tape is not required, and the stripping is very easy. Since the silicone rubber has excellent gas permeability, the gas permeability of the presser roll is kept good.

As a method of coating the silicone rubber on one surface of the aromatic polyamide resin tape, a lining process in which the silicone rubber is melted by heat and adhered to the base tape is preferable.

Others are the same as in the first invention of the present application, and the connection portion of the rubber / plastic insulated cable is formed.

(Example) An example of the present invention will be described.

Example 1 Two strips of 275 Kv power cable (3000 mm ² , insulation thickness 24 mm) to be connected are stripped off, the conductors are connected by sleeves, and then they are bonded to low density polyethylene (melt index 3.2, density 0.922 g / cm ³ ). The composition to which 2% of mill peroxide was added was provided in a mold to a thickness of 24 mm. A Kevlar cloth tape having a thickness of 0.24 mm, a width of 50 mm, and a tensile strength of 700 kgf was wound around the uncrosslinked reinforced insulator 10 laps in 1/2 wrap. Then, the temperature on the conductor sleeve is 150 ℃ x by normal infrared heating.
The reinforcing insulator was crosslinked by heating for 2 hours or more.

The occurrence rate of voids in the insulator of the connection portion thus formed was 300 / mm ³ , and the water content was 100 ppm. The void generation rate was observed under a microscope of 300 times, and the water content was measured by coulometric titration by the Karl Fischer method. The force required for stripping was 10 to 15 kgf / inch.

Example 2 The Kevlar cloth tape in Example 1 was coated with silicone rubber by lining to a thickness of 0.15 mm. Then, the silicone rubber side was made to be the reinforcing insulator side, and the connection part was formed in the same manner as in Example 1 except for the above, and the same test was conducted.

The occurrence rate of voids in the insulator of the connection portion thus formed was 300 / mm ³ , and the water content was 100 ppm. The void generation rate was observed under a microscope of 300 times, and the water content was measured by coulometric titration by the Karl Fischer method. The force required for stripping was 3 to 5 kgf / inch.

Comparative Example 1 When the Kevlar cloth tape in the example was replaced with a Kapton tape and the production and measurement were carried out in the same manner as in the example, the void generation rate was 8000 pieces / mm ³ , and the water content was
It was 250 ppm.

Comparative Example 2 When the Kapton tape in Comparative Example 1 was wound back and forth 30 times with a 1/2 lap, and then manufactured and measured in the same manner as in Comparative Example 1, the void occurrence rate was 50000 pieces / mm ³ , the water content. Was 400 ppm.

(Effects of the Invention) According to the present invention as described above, the gas and water in the reinforced insulator are released through the aromatic polyamide resin tape, so that it is possible to suppress the generation of voids and the residual water at the time of forming the connection portion to be extremely low. It is possible to form a connection portion having excellent insulation performance. Further, since this tape is excellent in air permeability and mechanical strength, it does not require a separate holding tape, thus improving workability.

[Brief description of the drawings]

The drawings are vertical cross-sectional views for explaining a method for forming a connecting portion of a rubber / plastic insulated cable according to the present invention. 1 ... Conductor connection part 2 ... Reinforcing insulator 3 ... Aromatic polyamide resin tape

Claims (2)

(57) [Claims] 1. A connection between a rubber and plastic insulated cable, characterized in that an aromatic polyamide resin tape is wound around an outer periphery of a reinforcing insulator provided on a conductor connecting portion of the rubber / plastic insulated cable and heated. Forming method. 2. A tape in which one side of an aromatic polyamide resin tape is coated with silicone rubber is provided on the outer periphery of a reinforcement insulator provided on a conductor connecting portion of a rubber / plastic insulation cable, and the silicone rubber side is the reinforcement insulator side. A method for forming a connection portion of a rubber / plastic insulated cable, which comprises applying a presser winding so as to be heated and heating.