JPS6185007A - Heat-shrinkable coated material for connecting cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a heat-shrinkable covering for connecting parts of electrical and communication cables, and particularly relates to a heat-shrinkable covering for cable connections that has good sealing properties in the coated state. 3 and 4, which relate to shrinkable coatings, show the state in which a connecting portion of a communication cable is covered with a conventional heat-shrinkable coating. This heat-shrinkable covering 1 has lips 3 protruding along both side edges on the outer surface of a sheet-like heat-shrinkable body 2, and a heat-sealing layer 4 on the inner surface. The heat-shrinkable body 2 is made of stretched crosslinked polyethylene or the like and has heat-shrinkability in the width direction fEiJ (circumferential direction in Figure 3), and the f7tJ% adhesive layer 4 is made of low-density polyethylene or IA ( It is formed from a fusion agent whose main component is ethylene-vinyl acetate copolymer), and has heat-fusion properties for cable sheaths and the like. and.

As shown in the figure, the heat-sealing layer 4 is wrapped around the connecting portion 7 of the main cable 5 and the branch cable 6.6, and the heat-sealing layer 4 is brought into contact between its both side edges and the branch cable 6.6, and heated in the next state. As a result, it is shrunk and heat-sealed to the connecting portion 7, thereby sealingly covering the connecting portion 7.

"Problems to be Solved by the Invention" By the way, when heating such a heat-shrinkable coating, it is desirable to heat the whole as uniformly as possible;
When using a burner, torch lamp, etc. as a heating means,
The heating condition depends on the skill level of the operator, and uneven heating tends to occur (for example, as shown in FIG.
．． There is a possibility that a gap S may occur at the seam B between the joints 6 and 6, and the sealing state of the connection portion 7 may become incomplete. Therefore, the void S
In order to suppress the occurrence of this, it may be possible to adjust the fluidity or melting point of the heat-sealing layer 4.

If the heat-sealing layer 4 is made of EVA, for example, if a material with a low vA (vinyl acetate) content of 1 is used, the adhesive strength with the connecting portion 7 will decrease.

When a material with a low molecular weight and high fluidity (melt index) is used, the strength of the material decreases and the seam A
, B, etc., the problem arises that airtightness is impaired.

"Easy Means for Solving Problems" In order to solve the above-mentioned problems, the present invention provides a thermal adhesive layer in which an unsaturated dicarboxylic acid or its This method uses a composition mainly composed of a specific thermoplastic elastomer grafted with an anhydride.

"Function" When the heat-shrinkable coating for cable connections of the present invention is heated, the heat-sealing layer easily melts and flows to fill the voids and further bond to the connection parts. Demonstrates excellent adhesive strength at gaps or seams.

“Example” An example of the present invention will be described below based on FIG. 1 and FIG.
Is there heat shrinkage in the same direction as Figure X-X? It also has ribs 3 and 7? + On the inner surface of the heat-shrinkable body 2, a heat-sealing layer 9 is provided, which is made of a composition mainly composed of a specific thermoplastic elastomer, which is obtained by grafting α% of dicarbonate or its anhydride onto an ethylene/α-olefin copolymer. It is earthy.

The ethylene/α-olefin copolymer includes ethylene, an α-olefin having 3 or more carbon atoms, such as propylene, 1-butene, 1,4-methyl-1-pentene, l-hexene, l-octene, butadiene, and isoprene. , dicyclopentadiene, 5- x t-2-norbornene% 1.6-hexadiene and other conjugated dienes are used, and 50 to 95 moles of ethylene, 5 to 5 to The ultimate ratio of 0 to 3 moles of conjugated diene is preferably 50% by mole. i fcm unsaturated dicarboxylic acid or its anhydride, maleic acid.

Fumaric acid, taconic acid, citraconic acid, nadic acid, maleic anhydride, citraconic anhydride, nadic anhydride, etc. are used. Graft polymerization of unsaturated dicarboxylic acids, carboxylic acids, or anhydrides thereof is then carried out in a reaction solvent using a radical A-initiator such as a peroxide. This thermoplastic elastomer has excellent melt flowability, good adhesion, and high heat distortion temperature (also has good heat resistance), and can be extruded or injection processed into any shape, and has a heat-adhesive layer. This thermoplastic elastomer is suitable as a material for making the material.Additionally, this thermoplastic elastomer may contain antioxidants and various stabilizers as needed.

It is also possible to form a heat-fusible layer by appropriately distributing fillers, pigments, etc.

Heat-shrinkable covering for cable connection 8 configured in this way
As in the conventional case, the heat-sealing layer 91 is placed inside and wrapped around the connection part 7 of the cable, and the heat-sealing layers 9 are butted together at both edges, etc., and then heated using a burner or a torch lamp. Shrink it by heating it before use. During this heating, the heat-sealing layer 9 is easily melted.

Because of its good fluidity, as shown in Figure 2, the gaps created at the seams A on both side edges or the seams B between the branch cables 6 and 6 are filled, and these seams A are filled.

Bt airtight C: Bonds and firmly adheres to the surface of the connection part, and does not easily peel off at all.

Next, regarding the heat-shrinkable covering of the present invention (a) and the heat-shrinkable covering having a heat-sealing layer made of EVA, that is, comparative examples middle), (c), and ni), the sealing performance and cable sheath ( Peel strength against polyethylene (JISK 6
854) and the results are shown in Table 1 to clarify the effects of the present invention. However, in Table 1, the sealing test l is 6.
Sealing test 2 was conducted in a constant temperature hot water bath at 0°C, and in a constant temperature atmosphere at 60°C, each connection part was 0. By/cm
This is the result of a test to check for gas leaks by applying a gas pressure of 0.4K to the connection.
After applying a gas pressure of 107+2, heat from 60°C to -30°C.
These are the results of a comparative test to detect gas leaks after performing the heat cycle treatment for 1 cycle from 12:00 to 12:00. In addition.

The numerical value indicates the number of passes without gas leak out of 10 tests.

As shown in Table 1 (D), the VA content was increased to lower the Vicat softening point compared to Comparative Example (B), and the following Comparative Example (
C) and a thick melt index (for the comparative example), both sealability and peel strength deteriorate. On the other hand, the Vicat softening point is lower than that of the heat-shrinkable coating (I) Fi of the present invention and the comparative example (B).

It also has a high melt index and high tensile strength (material strength). Therefore, as shown in the numerical values, it has excellent sealing properties and peel strength (adhesive strength).

In the above embodiment, the heat-shrinkable body 2 is not limited to a sheet-like structure, but the heat-sealing layer 9 may be provided on the inner surface of a tube-like or sleeve-like heat-shrinkable body.

"Effects of the Invention" As explained above, according to the present invention, unsaturated dicarboxylic acid or its anhydride is grafted onto the heat-adhesive layer t ethylene/α-olefin copolymer, and then the thermoplastic elastomer Since it is composed of a composition mainly composed of It is possible to firmly adhere and airtightly adhere to the connection portion, thereby improving the sealing performance in the covered state and further improving the workability during heating.

[Brief explanation of drawings]

Figure aE1 and Figure 2 show one embodiment of the present invention, Figure 1 is a perspective view, Figure 2 is a cross-sectional view of the branch part in use, and Figure 3 is a diagram of a conventional heat-shrinkable covering. A perspective view showing the state of use, Figure 4 is a view taken along the line ■-■ of Figure 3. 2...Heat shrinkable body, 3...Rib, 5...・
...Main cable, 6...Branch cable, 7
. . . Connection portion, 8 . . . Heat shrinkable coating for cable connection % 9 . . . Heat sealing layer % A. B...Seam %S...Gap. \, 1. - Figure 2 Figure 4

Claims (1)

[Claims] A heat-sealable layer (9) is provided on the inner surface of a heat-shrinkable body (2) that has heat-shrinkability and is in the form of a sheet or tube. 1. A heat-shrinkable coating for cable connections, characterized in that it is composed of a composition mainly composed of a thermoplastic elastomer grafted with an unsaturated dicarboxylic acid or its anhydride.