JPS5979733A - Preparation of heat-shrinkable sheet - Google Patents

Abstract

PURPOSE:To enhance the efficiency of heat-shrinking work, by applying unidirectional orientation in a width direction to a sheet main body having such a configuration that ribs are formed to both lateral side parts of one surface thereof each in a produced state and the both side parts thereof in the vicinity of the ribs are made thicker than the other part. CONSTITUTION:A sheet main body 11 and ribs 12, 12 are formed by extrusion molding of unbridged polyethylene to obtain a sheet having such a sectional shape that both side parts 11a, 11a thereof are made thicker than the other part. In the next step, one surface side having the protruded ribs 12, 12 is irradiated with high energy radioactive rays to integrally bridged the sheet main body 11 and the ribs 12, 12. Subsequently, the sheet main body 1 is unidirectionally oriented in the width direction thereof. In this case, the sheet main body 11 is oriented in such a way that both side parts 11a, 11a are largely oriented as compared with the other part by a method for applying constant tensile force after applying abrupt tensile force and each of them reaches a thickness equal to that of the other part.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to the fI+7 construction of a dj% 1117 shrinkable sheet used for covering cable connections.

In general, as one method for sealing the joint formed when two cables are connected, a spacer 2, an aluminum sleeve 3, etc. are connected to the joint 1a of the cable 1, as shown in Fig. 1. A vertically divided heat-shrinkable sheet 4 is placed over the film, and both sides are sandwiched between a plurality of glues, lips 5, etc., and the film is heated and shrunk. This heat shrinkable sheet 4
consists of a sheet body 6 that is contractible in the circumferential direction of the cable 1, and ribs 7.7 that protrude from the outer surface of both sides of the seat body 60! The inner surface is provided with adhesive properties such as heat fusion properties.

Conventionally, the manufacturing method for this heat-shrinkable sheet was to produce a heat-shrinkable sheet in the width direction (
The cable is designed to have as much uniform shrinkage as possible in the circumferential direction of the cable. For example, as shown in FIG. 2, is the shrinkage uniform on the mandrel 8 in the length direction (wrapping direction)? A cross-linked stretched plastic tape having the above structure is wound multiple times to form a sheet main body 6P, and the ribs 7 are adhered thereon. After drying, cut the rib 7 in the axial direction from the center of the rib 7 as shown by (a) - n in Fig. 2, dividing the rib 7.7 into two.
The heat-shrinkable sheet 4 is obtained by bending each section in the direction of 90 degrees away from each other.

However, EQ'+ produced by such a method
IIV Pak i 1+'I: The sheet has uniform shrinkability in all four directions, but as shown in Figure 5, when it is covered with the connection ^Is 1. Due to the elastic action of the sheet 4 itself, it is easy to create a gap 1 (10) near the seam 9 between the inner surfaces of both f) I [1 parts. In order to adhere the nearby inner surface to the circumferential surface of the connecting part 1'a, skill is required for the method of holding the clip 5 and the plp contraction work.
There is a problem that plasticity is reduced.

This invention was made against the background of the previous ff+Y situation, and improves the efficiency of heat shrinkage operation and improves sealing performance. ``Method for using a heat-shrinkable sheet 1) i) The purpose is to provide
Part σ) Form and keep the meat 1r and l thicker than other parts,
Next, the sheet body is stretched a little in the width direction so as to make the entire thickness (11) uniform, thereby giving both sides a shrinkage ratio greater than that of the other parts.

The present invention will be explained below based on an embodiment shown in FIGS. 4 to 7.

First, the sheet main body 11 and the lips 12 and 12 made of uncrosslinked polyethylene or the like are extruded and shaped.
A sheet having a cross-sectional shape as shown in the figure is formed in which both side parts 11a and 11a are thicker than other parts. Next reply 12
．． High-energy radiation is irradiated from one side from which the sheet body 12 protrudes to crosslink the sheet body 11 and the lips 12 and 12 together.
tIlh stretch. During this stretching, according to the research of the tree inventor, the attachment of the lip 12.12 is on both sides 11 a near the root.
, lla tend to be subjected to tensile force throughout the year, and tend to be stretched more than other parts. Therefore, by taking advantage of this phenomenon, for example, by applying a sudden tensile force and then applying a constant tension, the both side parts 11a11a are stretched to a greater extent than the other parts, and quickly reach the same thickness as the other parts. The sheet main body 11 is stretched until. If the method described above is insufficient, stretch only the both sides until the entire thickness is uniform (see Figure 5). By making the entire thickness uniform in this way, a Q-shrinkable sheet 13 can be obtained in which both sides 11a and 11a of the sheet main body 11 have a higher shrinkage rate than other parts.

Also this J↓7. If the sheet main body 11σ) is not cross-linked, it will naturally have heat-adhesive properties, but if you apply a heat-sealing type adhesive or a wet-adhesive adhesive, etc. You may also use cloth.

The heat-shrinkable sheet 13 produced hastily in this manner is wrapped around the connecting portion 1& with one side (til+) through which the lips 12 and 12 protrude through the spacer 2, aluminum sleeve 3, etc. , lla are used by sandwiching them between clips 5 or the like with their inner surfaces facing each other.

This Itjj has a gap 10 at the seam 9 'd'e of both side parts 11a and lla, similar to the conventional sheet to JIV shrinkable sheet.
Of course, it is easy to do this, but in the present invention, both sides 11a and lla of the seat body 110 have more I than other parts.
IM-kun;・By giving the i rate of ζ1, there is a difference in the Il17Mf rate between it and other parts, and by using this difference in shrinkage rate, the area around seam 9 is heated and contracted. 1Lf of
l 1rff 10 can be removed.

For example, the range fl) shown in Figure 5 is 60% of the original size.
Furthermore, if the area around both sides 11a and lla (c) shrinks to 50% of its original size, this 10% relative difference can be utilized. These theories.

In order to simplify the clarity, both sides 11a11 are shown in FIG.
1! Considering only the relative contraction of L, AB and H E1
1) Dimension e. Get e = (5 [1/60) go
k-contracts, and the shape of A B CD E F changes as shown by A'BCDEF' shown by one line between two points. In other words, the area surrounded by A/BCDEF' becomes 50/60 of the area surrounded by Ar5CT)EF by decreasing from eo to e.
It becomes the degree of aptitude.

In this case, if the ratio of the area occupied by the culm inside and the gap 10 surrounded by ABCDEF is 10150 or less, then both sides! 'Fl (111L, the thickness of 11a increases in inverse proportion to the decrease in thickness JJII t, , both sides fil 1
Since the area occupied by a, '11 & should not change, the gap 10 is removed as a result of the both sides 11a111a entering the gap H10. Therefore, the inner surfaces near both sides of the seam 9 are tightly adhered to the circumferential surface of the connecting portion 1a, and the entire circumferential surface of the connecting portion 1a can be sealed (see FIG. 7).

Note that the difference in shrinkage rate between both sides and other parts is determined by the difference in flesh lip between both sides and other parts before the sheet body is stretched. Therefore, the area of the gap is taken into account. It will be more effective if the thickness of both sides is set by

I J:, +? 'P As explained, according to this invention,
The following '8) results can be obtained.

0 The thickness 19 on both sides of the sheet body is formed to be thicker than the other parts, and when stretching the sheet body, a tensile force is applied to both sides side by side to reduce the overall thickness, This allows both sides to be given a higher shrinkage rate than other parts, and the relative difference in shrinkage rate between both sides and other parts can be used to eliminate gaps that tend to form near the seam of both sides. As a result, it is possible to obtain a heat-shrinkable sheet with a sealing property.

■ With K, which can give the other 1■-preparative shrinkage rate to both full parts of the sheet body, it is possible to obtain a heat-shrinkable sheet with high efficiency in heat-shrinking work.□

[Brief explanation of the drawing]

FIG. 1 is a perspective view illustrating the used part of the heat-shrinkable sheath;
FIG. 2 (2) to 0) is an explanatory diagram of an example of a conventional manufacturing method,
FIG. 3 is a view along the arrow II-III 14 of FIG. Figure 1, Figure 6, and Figure 71m are explanatory diagrams of the operation of the manufacturing method according to the present invention. 11...Seat body, 11a...fltl
lfL 12...Lip, 13...Heat shrinkable sheet. Applicant Fujikura Electric Cable Co., Ltd. Agent Patent Attorney Takeshi Shiga Figure 3 Figure 4 Figure 5 Figure 0 Figure 7

Claims (1)

[Claims] Both sides (11a11a) of one side of the seat body (11)
) with protruding ribs (12, 12), and rl
fl ffl'! Both 11111 parts of meat near the ribs p
The sheet body is uniaxially stretched in the width direction, and the sheet body is uniaxially stretched in the width direction, and the other parts are 11 of heat-shrinkable sheets having a characteristic of 111' to determine the shrinkage rate of
(τ! Construction method.