JPS5935331B2 - Method for producing a heat-shrinkable polyolefin sheet having unbonded parts that divide the film thickness into several parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a heat-shrinkable polyolefin sheet having unbonded parts that divide the film thickness into several parts.

For example, in order to prevent corrosion on the surface of a metal tube, a heat-shrinkable polyethylene tube or the like is placed over the metal tube and heated to shrink the tube and tightly coat the metal tube.

If the corrosion protection of the metal pipe is poorly implemented, or if the corrosion protection function deteriorates over time, the defective part or the part with deteriorated function must be repaired.

This repair work is usually performed by wrapping similar sheets. In this repair work by wrapping sheets, unless the joint strength of the side seams of the wrapped sheets is made very high, the seams will separate during subsequent heat shrinkage and the work will often fail.

Such failures occur very often when the side edges of the sheets are simply overlapped and bonded. Therefore, sheets of the same type with the same width as the side edge of the sheet are pasted so that two sheets are separated and layered in the longitudinal direction at the side edge, and such sheets are used for repairing the side seam. In recent years, attempts have been made to overlap the two sheet portions with each other to improve the bonding strength.

However, if a separate sheet of the same type is attached to the side edge, various questions arise as to how well it can withstand the stress during shrinkage mentioned above. Furthermore, when the thickness of the repair sheet exceeds a certain level, the thickness of the same type of sheet is added to the repair sheet, resulting in various problems with the film thickness.

Therefore, cutting the side edge of the repair tape into two pieces has been done, but such cutting work can only be done when the thickness of the sheet is greater than the thickness that allows the above-mentioned cutting. .

The inventor has completed this invention after extensive research into a method for manufacturing a heat-shrinkable polyolefin sheet that is suitable for such purposes and has an unbonded area that divides the film thickness into two, for example at the side edges. It is.

That is, the present invention provides a polyolefin tape or film that has been given heat-shrinkability by a desired method such as electron beam irradiation, chemical crosslinking, or stretching, and is wound on a winding core at a desired position between the laminated layers. A separator in which the windings are laminated in the longitudinal direction while inserting a separator with releasability on both sides, and then this is heated to weld and integrate all the windings and laminations.After that, the winding core is pulled out, and the resulting hollow body is inserted into a separator. This is a method for producing a heat-shrinkable polyolefin sheet having an unbonded part that divides the film thickness into several parts, which is characterized by making an incision on the top or between the separators and pulling out the separator.

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 shows a winding laminate 2a of a polyethylene tape or film 2 cross-linked and heat-shrinkable by irradiation with an electron beam or the like formed on a winding core 1; This is a separator that is inserted halfway along the length of the laminated layer in the longitudinal direction and has removability on both sides.

All the wound layers 2a are integrated by being heated to a temperature higher than the melting temperature of the polyethylene tape or film 2 used as the base material. After cooling and solidifying, this material is incised along line A in the figure (i.e., above the inserted separator), and when the separator 3 is removed, as shown in FIG. A sheet S1 having the thickness-divided portions 4a and 4b on both side edges is obtained. FIG. 2 shows that three separators 3a, 3b, and 3c are similarly distributed at positions equidistributing the outer periphery of the wound laminated layer 2a in the method shown in FIG. 1 above.
An example is shown in which three sheets similar to the above are obtained at the same time by inserting the separator and cutting along lines B, C, and D on the separator insertion part.

Next, FIG. 3 shows that when inserting and arranging the same separators as described above, two separators 3d and 3e are positioned slightly close to each other on the circumference, and after making an incision along line E in the middle of both separators, By pulling out the inserted separators 3d and 3e, a sheet S2 can also be obtained in which the thickness dividing portions 4c and 4d do not open to the side edges of the sheet, as shown in FIG.

By changing the positions of the above-mentioned incision lines A, B, C, D, and E, the above-mentioned film thickness division parts may be asymmetrical on each sheet, or may have only one width. It is clear that sheets of a wide variety of configurations can be obtained.

It is also possible to easily change the aforementioned dividing thickness by shifting the insertion position of the separator to one side from the middle of the film thickness of the sheet. The sheet produced by the method of the present invention can be used as a corrosion protection material for steel pipes or the like or as a corrosion protection layer repair material by applying an adhesive to one side thereof.

In addition, when attaching the ends to these devices, if the structure has branches at both ends, use a strong adhesive on the branches or heat or heat the end joints. By pressure welding, it is possible to interlock the branch parts and achieve extremely strong joints. Further, as shown in FIG. 5, in the case of a device having an unwelded portion surrounded by a welded portion, this portion can be used to mechanically join both ends and attach the device.

According to this invention, by simply inserting a separator and cutting out a tube, a sheet having an unbonded part that divides the film thickness into several parts can be obtained, making it easy to manufacture. Since it is integrated with the main body, there is less risk of the above-mentioned strength problems, and furthermore, since the arrangement and configuration of the unbonded parts can be diversified, it can easily be adapted to various uses, and its industrial value is high. Very large.

The present invention will be specifically explained below with reference to Examples.

Actual example: Using a cross-linked stretched polyethylene film with a heat shrinkage rate of 50%, 0.15 mm thick and 900 mu, which was cross-linked by irradiation with an electron beam of 18 Mrad, the diameter was 600 mm and the length was 10 mm.
Wound 4 layers on a 00mm core (0.6mm thick), then 0.1m7 thick on top! Three separators each having a L1 width of 200 mm and a length of 1000 mm that have been subjected to mold release treatment on both sides are placed at positions that equally distribute the circumference between the wound layers as shown in Fig. 2, and then the above-mentioned polyethylene is further placed on the outside. The films were wound in layers to a thickness of 0.6 mm.

Next, the thus obtained wound laminate was heated at 160° C. for 60 minutes to weld and integrate the wound and laminated film layers. After cooling, the core was extracted to obtain a tube.

After removing the three separators from the tube, incisions were made at the positions of lines B, C, and D in Fig. 2, and both ears were cut off.The tube had a thickness of 1.2 mm and was 800 x 660 m77! Three sheets were obtained. These sheets have a width of 10 mm on both side edges.
It had an unwelded part with a thickness of 0 mm divided into two parts, and had a shrinkage rate of 50%.

Example 2 Cross-linked stretched polyethylene film (shrinkage rate 20% thickness 0.
15 mu 1 width 900 mm), diameter 300 mm length 10
6 layers are wound on a 00mm core (0.97nm thick), and then 0.1mm thick and 100TfLTfL is wound on top of this.
1. Prepare two separators with a length of 850 mm that have been subjected to release treatment on one side and fold them in half in the longitudinal direction so that the treated side faces outward. As if the distance between the separators was 150 degrees (
As shown in FIG. 3), the above-mentioned polyethylene film was further wrapped around the outside to a thickness of 0.97 ftm.

Next, the thus obtained wound laminate was heated at 160 μC for 50 minutes to weld and integrate the wound and laminated film layers, and after cooling, the core was extracted to obtain a tube.

After removing the two separators from the tube,
At a position 5mm from the end of one separator insertion part,
An incision was made as shown in the figure, and both ears were cut off to obtain a sheet with a thickness of 1.8 mm and a size of 700 x 940 mm. As illustrated in FIG. 5, this sheet had a heat shrinkage rate of 20% and had unwelded portions that did not open at both side edges.

Example 3 Cross-linked stretched polyethylene film (shrinkage rate 75%, thickness 0
．． After winding 8 layers (0.8 mm thick) on a winding core with a diameter of 4007 nm and a length of 1000 mm using a 1 mu 1 width 900 m0, 0.1 dragon thickness, width 150 mm, length 100
The first layer was made by laminating uncrosslinked polyethylene films of the same size on both sides of a 0 mm double-sided release-treated separator.
It was arranged as shown in the figure, and the above-mentioned polyethylene film was wrapped around the outside to a thickness of 0.87n71L.

Next, the thus obtained wound laminate was heated at 1600 C for 60 minutes to integrally weld each layer of the wound and laminated film, and after cooling, the core was extracted to obtain a tube.

The separator was removed from the tube, and an incision was made along line A in Figure 1, and both ears were cut off to make a tube with a thickness of 1.8 mm and an 80 mm diameter.
A sheet of 0×1250 mm was obtained. This sort had a thickness of 75 m7IL on both sides, and had a shrinkage rate of 75%, with uncrosslinked polyethylene layered on the opposing inner surface.

[Brief explanation of drawings]

Figures 1 to 3 are cross-sectional views of portions formed by winding and lamination on a winding core to explain three examples of the method of the present invention, and Figures 4 and 5 are sloped surfaces of sheets obtained by the method of the present invention. It is a diagram. 1... core, 2... film, 3~3
e...Separator, 4a-4d...
Film thickness division part (unbonded part).

Claims (1)

[Claims] 1. A polyolefin tape or film that has been given heat-shrinkability by a desired method is wound on a winding core in the longitudinal direction at a desired position between the desired winding layers, while inserting separators with peelability on both sides. After the layers are laminated twice, the layers are heated to weld and integrate all the layers, the core is pulled out, the resulting hollow body is incised on the inserted separator or between the separators, and the separator is pulled out. A method for producing a heat-shrinkable polyolefin sheet having an unbonded part that divides the film thickness into several parts.