JPH0636641B2 - Waterproofing method of terminal connection part of covered electric wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a waterproofing method for a terminal connecting portion of a covered electric wire.

<Prior Art> As a conventional technology, there is a method disclosed in Japanese Utility Model Publication No. 52-5255. According to this method, the following methods are disclosed when the terminals of the covered electric wires are connected to each other and the connection portion is waterproofed.

(1) The coating material for both coated electric wires is an ester urethane resin.

(2) An ether type urethane resin is applied to the surface of the covered electric wire.

(3) Connect the ends of the covered electric wire in the above state,
An ether type urethane resin is molded on the connecting portion.

Further, conventionally, when measuring the temperature in water using a temperature sensor, a waterproofing method generally including the following steps (a) to (c) is adopted.

(A) Connect the lead wire of the temperature sensor and the end of the wire.

(B) Prepare a tubular metal pipe with one end closed and the other end open, and push the wire connected to the temperature sensor into the pipe from the open end, and the temperature sensor reaches near the closed end of the pipe. Insert up to.

(C) Fill the space between the inner wall of the metal pipe and the electric wire connecting the temperature sensor with the heat transfer material.

According to the above steps (a) to (c), the temperature sensor enclosed in the metal closed tube is held in the water to be measured, taking care so that the open end of the sensor is not submerged in water, and the water temperature is measured.

<Problems to be Solved by the Invention> When the electric wire is waterproofed by the method disclosed in Japanese Utility Model Publication No. 52-5255, the ether applied to the coating surface exposed to the outside except the mold portion when the electric wire is used for a long time. The urethane-based urethane resin is deteriorated and easily peeled off, and the ester-based urethane resin, which is a covering material for the electric wire, is exposed at a portion where the ether-based urethane resin is peeled off. Since the ester-based urethane resin has a drawback of being hydrolyzed, the coating layer of the electric wire from which the ether-based urethane resin has been peeled off is hydrolyzed, and water will enter the conducting wire of the electric wire. Further, an extra means of applying an ether-based urethane resin to the surface of the covering material of the electric wire is required.

Further, in the conventional method of measuring the temperature in water, the heat of water is transmitted to the entire metal pipe and is further radiated from the portion above the water surface to the air, which causes an error in the measured value. Further, the metal pipe has the drawback that it does not bend freely and the device itself becomes large.

<Means for Solving Problems> The present invention solves the above problems by providing a waterproofing method as shown in (A) to (D) below.

(A) An insulated electric wire provided with an insulating layer on a conductor is covered with a silane crosslinked polyethylene resin to obtain a covered electric wire.

(B) The insulating layer and the covering material are removed from the end of the covered electric wire to expose the conductor, and the connected component is connected to the conductor portion.

(C) With the gel fraction of the coating material of the electric wire being suppressed to 0 to 40%, a silane-crosslinked polyethylene resin is applied to the above-mentioned connecting portion at a temperature higher than the extrusion temperature of the electric wire coating material. Embed and mold including the covering material.

(D) Further promote crosslinking of the mold portion and the entire electric wire coating material, and chemically bond molecules of the melted portion of the mold portion and the coating material.

The method of waterproofing a terminal connecting portion of a covered electric wire, which includes the above steps (A), (B), (C), and (D) ”is a feature.

<Operation> In the waterproof treatment method for the terminal connecting portion of the coated electric wire of the present invention having the above-described configuration, the gel fraction of the electric wire coating material is kept to 0 to 40%, so that each molecule of the electric wire coating material is , The state of semi-crosslinking is maintained. Therefore, when the electric wire connecting portion including the coating material in the semi-crosslinked state is molded with the same silane-crosslinked polyethylene resin as the coating material, the weldability between the molding material and the coating material is remarkably improved. In addition, since the temperature at which the mold is applied is set higher than the extrusion temperature of the wire covering material, the embedded wire covering material is melted by the hot mold part, and both the molding material and the wire covering material are melted and integrated. Turn into. Then, as the electric wire coating material and the molding material, since a silane cross-linked polyethylene resin having a property of reacting with atmospheric moisture to proceed with crosslinking even when left at room temperature is used, the crosslinking of the molding process is actively used, Molecules in the melted portion of the mold portion and the coating material chemically bond.

Due to the complex synergistic effect of the above-mentioned time series requirement of "suppressing the degree of crosslinking of the coating material to 40% or less, molding under the above temperature conditions, and then promoting crosslinking after the molding" The waterproof property has a remarkable effect that a special waterproof property which is about 10 times that of the prior art is obtained.

<Example> Example (1) Hereinafter, a waterproofing method for connecting a temperature sensor to an end of an electric wire and molding the connected portion will be described with reference to the drawings.

(A) Two insulated wires in which the insulating layer 4 is provided on the conductor 5,
A coated wire 1 is obtained by coating with a silane-crosslinked polyethylene resin (measured by JIS K-6760 as a melt index of 1 to 20 g / 10 min, preferably 5 to 15 g / 10 min) at an extrusion temperature of 160 to 185 ° C. Further, until the step (C), the gel fraction of the coating material (according to the measuring method of JASO D 608) is kept at 0 to 40%, preferably 5 to 25%, so that no crosslinking aid is used.

(B) As shown in FIG. 2, the covering material and the insulating layer 4 are removed from the tip end portion of the covered electric wire 1, and the taken-out conductor 5 and the lead wire portion of the temperature sensor 3 are soldered, crimped, welded, etc. Connect by the method (see Fig. 3). Also, after connecting,
The conductor 5 and the lead wire portion of the temperature sensor 3 may be fixed and insulated with an adhesive.

(C) As shown in FIG. 6, the tip of the electric wire 1 to the temperature sensor 3 is molded with a silane-crosslinked polyethylene resin of the same material. In the water-crosslinking method, the crosslinking gradually progresses with the passage of time, so this step should be performed before the gel fraction exceeds 40% (see FIG. 8).
The molding temperature is 190 to 220 ° C., which is higher than the extrusion temperature of the electric wire coating material. Moreover, the pressure is 15 to 20 kg /
Make into cm ² and mold.

(D) When fixing the sensor to the tip of the mold part, it is preferable to perform temporary molding so that the temperature sensor 3 and the conductor 5 are integrally fixed in position as shown in FIG. Temporary mold has a mold temperature of 160-185 ° C and pressure of 1
Perform at 0 kg / cm ² . Then, as shown in FIG.
The temporary mold portion 7 is fixed by the presser support rod 6 and the above-mentioned (C) is performed.
You may use for the mold in the process of.

(E) Care is taken to prevent water from seeping from the other end of the wire, soaking the whole wire and mold part in 60 ° C warm water to promote crosslinking of the whole wire, and at the same time chemically modify the molecules of the part where the coating material and the mold part are melted. To combine.

Example (2) A waterproofing method for molding electric wires and a connecting portion between electric wires as shown in FIG. 7 will be described.

(A) Two insulated electric wires provided with an insulating layer on the conductor 11 are provided with a silane crosslinked polyethylene resin (JIS K-6760).
The coated wire 9 has a melt index of 1 to 20 g / 10 minutes, preferably 5 to 15 g / 10 minutes) at an extrusion temperature of 160 to 185 ° C. Further, until the step (C), the gel fraction of the coating material (according to the measuring method of JASO D 608) is kept at 0 to 40%, preferably 5 to 25%, so that no crosslinking aid is used.

(B) As shown in FIG. 7, the conductor 11 exposed by removing the covering material and the insulating layer from the tip portions of the two covered electric wires 9
Connect to each other.

(C) The gel fraction of the electric wire coating material is 0 to 40%, preferably 5
The connection portion is molded with a silane-crosslinked polyethylene resin of the same material while suppressing the content to -25%. On this occasion,
Molding is performed at a temperature of 190 to 220 ° C. higher than the extrusion temperature of the electric wire coating material so that the surface portion of the electric wire coating material is melted.

(D) Immerse the entire wire and mold in hot water at 60 ° C to promote crosslinking of the whole while paying attention not to cause water from the other end of the wire, and at the same time, chemically bond the molecules of the melted part of the coating material and the mold. Let

A temperature sensor is connected to the tip of the covered electric wire to implement the embodiment (1).
As shown in Table 1, the waterproofness of the connection portion of the temperature sensor and the covered electric wire waterproofed in the step of 100 ° C. hot water was confirmed by the insulation resistance measurement and the airtightness test.

<Effects of the Invention> As described above, the waterproofing method of the terminal connecting portion of the covered electric wire of the present invention is performed by embedding a resin having adhesive property in the electric wire covering material in a state where cross-linking has progressed to make it waterproof. Special waterproofness of about 10 times is obtained as compared with the conventional one to be treated.

And the connection part of the temperature sensor using the waterproofing method of the present invention, since the connection part can be directly put into the water due to the above-mentioned special waterproof property, the temperature sensor is put in the protective tube for indirect measurement. Compared with the conventional one, the temperature measurement accuracy is greatly improved, and the structure of the temperature sensor is simplified and miniaturized.

Further, in the waterproofing method of the present invention, no special waterproofing measures such as applying a resin having waterproofness to the surface of the covering material becomes unnecessary, so that the waterproofing process of the connecting portion is simplified and the special waterproofing process is performed. The waterproof treatment described above has no side effects such as peeling of the waterproof resin, excellent waterproof property is stable for a long period of time, and the life of an electric wire connecting article that requires waterproof property is stable for a long period of time.

There are various effects described above.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view of a covered electric wire according to an embodiment of the present invention in which a temperature sensor is connected to a tip thereof, and FIGS. 2 to 6 are waterproof treatments at a connecting portion between the temperature sensor and the covered electric wire according to the present invention. It shows a process of applying. FIG. 7 is a partially cutaway sectional view of a connection portion between a covered electric wire and a covered electric wire according to an embodiment of the present invention, which is waterproofed. FIG. 8 shows the silane cross-linked polyethylene resin used in the examples of the present invention.
It is a graph which shows a crosslinking rate (gel fraction-crosslinking time) in 30 degreeC and 95% humidity. In the figure, 1 and 9 are covered electric wires, 2 and 10 are molded parts, 3 is a temperature sensor, 4 is an insulating layer, 5 and 11 are conductors, 6 is a pressing support rod, 7 is a temporary molded part, and 8 is a covered electric wire. The chemical bonding surface of the mold portion, 12 indicates the connecting portion of the conductor of each covered electric wire.

Claims (3)

[Claims] 1. A waterproof treatment method for a terminal connecting portion of a covered electric wire, which comprises the following steps (a) to (d): (A) An insulated wire provided with an insulating layer on a conductor is covered with a silane crosslinked polyethylene resin to obtain a covered wire. (B) The insulating layer and the covering material are removed from the end of the covered electric wire to expose the conductor, and the connected component is connected to the conductor portion. (C) With the gel fraction of the coating material of the electric wire suppressed to 0 to 40%, the silane cross-linked polyethylene resin is applied to the above-mentioned connecting portion at a temperature higher than the extrusion temperature of the electric wire coating material. Embed and mold including the covering material. (D) Further promote crosslinking of the mold portion and the entire electric wire coating material, and chemically bond molecules of the melted portion of the mold portion and the coating material. 2. A method for waterproofing a terminal connecting portion of a covered electric wire, wherein the connected component according to claim 1 is an element such as a temperature sensor. 3. A waterproofing method for a terminal connecting portion between electric wires, wherein the connected component according to claim 1 is a covered electric wire.