JPH0417009B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a heat-shrinkable sheet used for covering connection parts of communication cables and the like.

In general, one method of sealing the connecting portions of communication cables, etc. by covering them with a cover is to cover the connecting portions 2 of communication cables 1, 1 with a heat-shrinkable sheet 3 in the shape of a vertical sleeve, as shown in Fig. 1. This heat-shrinkable sheet is heated and shrunk by wrapping it around the sheet.

As shown in FIG. 2, this heat-shrinkable sheet 3 is composed of a heat-shrinkable layer 3A that can be heat-shrinkable in the circumferential direction, and a heat-sealing layer 3b laminated inside this heat-shrinkable layer 3A. The heat-shrinkable layer 3A is, for example, made by uniaxially stretching a cross-linked polyethylene sheet to enable heat-shrinking in the circumferential direction when formed into a sleeve shape, and the heat-sealing layer 3b is made of a non-crosslinked polyethylene sheet. It is made of a heat-sealable material such as polyethylene.

Further, the electric heat-shrinkable sheet 3 has a heat-shrinkable layer 3A.
The inner surfaces of both side edges 3c in a direction substantially perpendicular to the direction of contraction of the heat-sealing layer 3b, that is, the surfaces of the heat-sealing layer 3b, are faced to each other and are butted against each other, and are wound around the connecting portion 2, and
Pressing rods 4, 4 are provided vertically along the outer surface of the edge portion 3c, that is, the side edge of the surface of the heat-shrinkable layer 3A.
It is designed to be heat-shrinked while being held between clips 5, 5 or other holding tools. Projections 6, 6 are attached to the side edges 3c of the heat shrink layer 3a to prevent the pressing rods 4, 4 from sliding off the surface of the heat shrink layer 3A.

By the way, although cross-linked polyethylene is used for the heat-shrinkable layer 3A and the protrusions 6, this cross-linked polyethylene has a weak point of poor adhesion. Therefore, it is conceivable to heat-seal the protrusions 6 to the heat-shrinkable layer 3A by means such as a heat press, but this is somewhat inefficient since it takes a long time to fuse. There is a possibility that the heat shrink layer 3A will shrink due to the heat generated during the application, and its heat shrinkability may be impaired when attempting to cover the cable connection portion.

This invention was proposed in consideration of the above circumstances, and provides a heat-shrinkable sheet in which the formation of protrusions is easy and the heat-shrinkability of the sheet itself is not impaired when the protrusions are formed. The purpose is to

The present invention will be described below based on an embodiment shown in the drawings.

FIG. 3 shows an intermediate material obtained by practicing the invention. In other words, an uncrosslinked organic polymer material, such as uncrosslinked polyethylene,
An extrusion molding machine extrudes the sheet into a sheet having the cross-sectional shape shown in FIG.

That is, at both side edges 3c, 3c of the flat heat-shrinkable layer-equivalent portion 3a, the heat-shrinkable layer-equivalent portion 3
Protrusions 6A, 6A are provided to protrude perpendicularly to the surface of a. Furthermore, flanges 6B, 6B are provided at the tips of the protrusions 6A, 6A, facing each other and protruding substantially parallel to the heat-shrinkable layer equivalent portion 3a. The length of the intermediate material thus formed may be a unit length or an integer multiple of a unit length suitable for being wrapped around a cable connection.

Next, high-energy radiation such as electron beams, beta rays, gamma rays, etc. is irradiated from the surface of this intermediate material, that is, the surface where the protrusions are present, so that the protrusions 6A, 6A and the flange are irradiated with high-energy radiation such as electron beams, beta rays, and gamma rays. Parts 6B and 6B are crosslinked simultaneously. Next, the pair of protrusions 6A, 6A of this crosslinked intermediate material
The sheets are each stretched outward in the width direction of the sheet using the same method. As a result, heat shrinkability is imparted to the heat-shrink layer equivalent portion 3a, and a heat-shrink layer 3A (see FIG. 4) is obtained.

When the heat-shrinkable sheet for cable connection obtained in this way is actually applied to the cable connection part, as shown in FIG. 4, a heat shrink layer 3A is wrapped around the cable connection part. After touching the ends 3c, 3c, the protrusions 6A, 6A
and a locking rod (not shown) inside each of the flange parts 6B, 6B.
is placed.

In addition, as another example, the heat shrink layer equivalent portion 3
A heat-sealing layer 3b, for example, uncrosslinked polyethylene, can be simultaneously extruded on the back side of the film a. Furthermore, instead of crosslinking by irradiation with high-energy radiation, a crosslinking agent can be blended in advance into an uncrosslinked polymeric material, this can be extruded into an intermediate material, and then crosslinked by heating.

In both of the above-mentioned methods, the protrusion 6A is extruded in advance in an uncrosslinked state, the protrusion 6A and the heat-shrinkable layer equivalent portion 3a are integrally cross-linked, and then the heat-shrinkable layer-equivalent portion 3a is The protrusion 6A can be easily provided on the heat-shrinkable layer 3A, and the protrusion 6A can be easily provided on the heat-shrinkable layer 3A.
It has the advantage that the heat shrinkability of the heat shrinkable layer 3A is not impaired when forming A.

As is clear from the above description, in the present invention, after extruding an intermediate material having the protrusions 6A in advance, this intermediate material is crosslinked and then stretched, so that the heat shrinkable layer is caused to undergo heat shrinkage. The protruding portion 6A can be formed without any problem. Furthermore, the intermediate material can be easily stretched in the width direction of the sheet by using the protruding portion 6A.

[Brief explanation of drawings]

1 and 2 show a conventional example of a heat-shrinkable sheet wrapped around a cable connection part, with FIG. 1 being a perspective view and FIG. 2 being a cross-sectional view. FIG. 3 is a cross-sectional view showing an intermediate material of a heat-shrinkable sheet according to an embodiment of the present invention, and FIG. 4 is a perspective view showing a state in which the heat-shrinkable sheet is wrapped around a cable connection portion. In the figure, 1 is a communication cable, 2 is a connection part,
3A is a heat-shrinkable layer, 3a is a portion corresponding to the heat-shrinkable layer, 3b is a heat-sealing layer, 3c is a side edge portion, and 6A is a protrusion portion.

Claims (1)

[Claims] 1. A non-crosslinked polymeric material is extruded to form a flat heat-shrinkable layer-equivalent portion 3a, and the heat-shrinkable layer-equivalent portion is formed substantially perpendicularly to the surface of the heat-shrinkable layer-equivalent portion along both side edges thereof. An intermediate material integrally having protruding ridges 6A, 6A is pre-molded, and then this intermediate material is crosslinked, and then the heat-shrink layer equivalent portion is formed using the ridges 6A, 6A. A method for producing a heat-shrinkable sheet for cable connection, comprising stretching 3a in its width direction. 2. The method of manufacturing a heat-shrinkable sheet for cable connection according to claim 1, characterized in that a heat-sealable layer 3b is simultaneously extruded on the back surface of the flat heat-shrinkable layer equivalent portion 3a.