JPS6049412B2 - Method for manufacturing plastic sheet with branch parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously manufacturing a plastic sheet with branched parts, in which the end part is branched into a plurality of sheets in the thickness direction.

Such plastic sheets with branched parts are widely used as anticorrosion materials for large diameter steel pipes and the like.

Conventionally, such a plastic sheet with branched parts is produced by inserting a thin plastic sheet, which is the material for a drum of a predetermined diameter, between the sheets, and a thin layer of polyolefin in a molten state that can be welded to the sheet as an intermediate layer. A thin strip of material with poor adhesiveness, i.e., a separator, is inserted into a predetermined position parallel to the axis of the drum, and then rolled and laminated, then heated, the whole is thermally welded, and then cooled to form a tube. It is manufactured by cutting the tube on the separator or along its edge.

Particularly when the material is a heat-shrinkable plastic film, it is essential to wrap it around a drum, laminate it, and heat treat it to prevent shrinkage during the welding process. However, in this conventional method, it is impossible to manufacture a plastic sheet with branched parts while continuously supplying a long sheet of plastic, so the cost inevitably increases. The object of the invention is to obtain a method for continuously producing branched plastic sheets which does not have the above-mentioned disadvantages. In the present invention, in order to continuously produce a plastic sheet with branched parts whose end parts are branched in a plurality of sheets in the thickness direction, (a) two long plastic sheets are stacked on top of each other; (b) inserting between the two sheets a thin layer of polyolefin in a molten state that can be welded to these sheets as an intermediate layer; , insert thin strips of desired size made of a releasable material with poor adhesion in the transverse direction of the sheet at desired intervals, and (c) then thermally welded and cooled to form an integrated sheet. (d) A method for manufacturing a plastic sheet with branching parts, which is characterized in that the integrated sheet is then cut in a direction transverse to the integrated sheet at the inserted portion of the thin strip. do.

When making a heat-shrinkable plastic sheet with branch parts by the method of the present invention, the heat-shrinkable plastic sheet is as follows:
Preference is given to using crosslinked heat-shrinkable plastic sheets, especially crosslinked polyethylene sheets.

In addition, the polyolefin that is sandwiched between such sheets as an intermediate layer must be able to be welded to the plastic sheet, and such polyolefin is usually a polymer of the same type as the plastic sheet and has a slightly lower welding temperature. Alternatively, one with low melt viscosity can be used. Particularly good results can be obtained by using a material whose adhesion has been improved by copolymerization or graft polymerization. Examples of such polyolefins include modified polyethylene and polyethylene copolymers. Furthermore, the thin strips serving as separators must be made of a female material with poor adhesiveness. As such a material, for example, polyethylene terephthalate film can be used. Next, embodiments of the present invention will be described with reference to the drawings.

Example 1 Width: 600T0n. ．． Electron beam irradiation (1.3 Mra
d) to obtain a gel fraction of 48%, and then at a temperature of 9
1 compared to before stretching with the same width after stretching at 0'C
．． The length was increased to four times the length and the strain was memorized by cooling to room temperature to obtain a so-called heat-shrinkable sheet.

As shown in FIG.
．． They were simultaneously fed in the same direction so as to overlap at a speed of 5 rn/min.

Modified polyethylene (product name:
Admar NEO5O, manufactured by Mitsui Petrochemical Industries, Ltd., was extruded from an extruder 3 as a film with a thickness of 40 μm, and inserted in a molten state between these sheets as an intermediate layer 4.
At this time, a thin strip of polyethylene terephthalate film (width 20 mm, length 60 mm, thickness 60 μm) 5.
The sheets were inserted in the transverse direction at intervals of m. Next, it was pressed by passing it through a two-stage roller 6 (through which cooling water with a water temperature of 25° C. was passed), and was air-cooled with an air blower to cool it to around room temperature to obtain an integrated sheet 7. The enlarged cross section of the generated integrated sheet is
As shown in the figure. Next, as shown in FIG. 3, this integrated sheet 7 is cut in the width direction of the sheet at the center where the thin strip 5 of polyethylene terephthalate film is inserted.
By peeling off and removing the thin leaf-like strips 5, the branched portion was bifurcated into two pieces. In this way, the branch part was branched into two sheets, and a heat-shrinkable plastic sheet with a branch part was obtained with a tape length of , by repeating this process or increasing the number of films and the number of extruded sandwich films.
I was able to create more than one branch.

[Brief explanation of the drawing]

FIG. 1 is a route map of the equipment used in one example of the method of the present invention;
FIG. 2 is an enlarged sectional view of an example of an integrated sheet obtained by the method of the present invention before cutting, and FIG. 3 is a perspective view showing an example of the cutting position of the integrated sheet obtained by the method of the present invention. be. 1,1″・・・Heat-shrinkable plastic sheet, 2
, 2″... Source of heat-shrinkable plastic, 3
... Extruder, 4 ... Middle layer, 5 ...
Thin leaf-like strip (separator), 6...two-stage roller, 7...integrated sheet.

Claims (1)

[Claims] 1. When continuously manufacturing a plastic sheet with branched parts whose terminal parts are branched into multiple sheets in the thickness direction, (a)
Two elongated plastic sheets are continuously fed in the same direction so as to overlap each other, and (b) a thin layer of polyolefin in a molten state that can be welded to these sheets is placed between the two sheets as an intermediate layer. At the same time, thin strips of a desired size made of a releasable material with poor adhesiveness are inserted in the transverse direction of the sheet at desired intervals, and (b
) Then, after heat welding, cooling is performed to form an integrated sheet,
(d) A method for producing a plastic sheet with branched portions, which comprises subsequently cutting the integrated sheet in the width direction of the sheet at the inserted portion of the thin leaf-like strip.