JPS6143197B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves laminating cellulose paper on both sides of a thermoplastic plastic film, and then applying this laminate to a plurality of metal rolls maintained at a temperature higher than the melting point of the thermoplastic plastic film used above. The present invention relates to a method for producing a laminate paper, particularly a plastic film/cellulose paper laminate used for power cable insulators, by heat-sealing the film and the cellulose paper by pressing them together.

BACKGROUND OF THE INVENTION Conventionally, laminate paper made by laminating thermoplastic plastic film and cellulose paper has attracted attention as an insulating material with low dielectric loss and high withstand voltage. The method for manufacturing this laminated paper is as follows:
A method of extruding a thermoplastic film into a film using an extruder and pasting cellulose paper under pressure on both sides of the film, or as shown in Fig. 1, cellulose paper is applied to both sides of a pre-formed thermoplastic film 1. A method is known in which sheets of paper 2 and 2' are overlapped and then introduced into a gap between two heating rolls 3 and 3' to be heated and pressurized and fused.

However, the former method has the problem that the extruded plastic film is cooled and solidified before or during contact with the cellulose paper, and therefore the adhesion between the two is generally poor. Secondly, with the latter method, it is difficult to initially set the dimensions of the roll gap so that a constant pressure is applied, and when laminating thermoplastic plastic film with large variations in thickness to cellulose paper, the narrow roll Creases tend to occur when passing through the gaps, and since the pressure area of the rolls is small, it is necessary to pass the plastic film through the rolls at a slow speed in order to sufficiently heat and fuse the plastic film to the cellulose paper, so the production speed is generally slow. There is a problem.

The present invention has been made to solve these problems, and provides a method for manufacturing laminated paper with excellent productivity.

As illustrated in FIG. 2, in the present invention, cellulose papers 2 and 2' are stacked on both sides of a thermoplastic plastic film 1 in a molten state, and then this laminate is fused into a thermoplastic film as described above. In producing laminated paper by heat-sealing the film 1 to the cellulose paper 2, 2' by contacting a plurality of metal rolls 3, 3' maintained at a temperature higher than the melting point of the film 1,
The plurality of metal rolls 3, 3' are arranged with a gap larger than the thickness of the laminated paper to be manufactured, and the laminate is arranged so that one side and the other side of the laminate are alternately connected to each of the metal rolls 3, 3'. This method of manufacturing laminated paper is characterized in that the sheet is passed between the metal rolls 3 and 3' in a meandering manner so as to be pressed and heat-sealed.

Although FIG. 2 shows an example in which two metal rolls are used in the method of the present invention, a larger number of metal rolls can be used as required.

In the present invention method, the reason for arranging multiple metal rolls is larger than the thickness of the laminated paper that should be manufactured, is the thickness of the laminated paper to be manufactured, that is, the melting state, and both sides and its sides. A total of 2
If the laminated paper is arranged with a gap larger than the sum of the thicknesses of the two sheets of cellulose paper, wrinkles are unlikely to occur while the laminated paper to be manufactured is passed in a meandering manner between the metal rolls so as to be in pressure contact with the metal rolls. It is from. Furthermore, the method of the present invention does not require any trouble in manufacturing, such as the need to apply a constant pressure in the gap between the rolls during fusion.

In the method of the present invention, the laminated paper to be manufactured is first brought into a molten state in the first roll by passing it in a meandering manner between metal rolls so that one side and the other side of the paper are alternately pressed against each of the metal rolls. One side of the thermoplastic plastic film is heated to a molten state and is thermally fused to the cellulose paper, and then the other side of the thermoplastic plastic film is heated in a second roll and is also thermally fused to the cellulose paper. By performing these steps alternately, the adhesion between the thermoplastic plastic and the cellulose paper is achieved extremely well. From the point of view of production speed, it has been found that the larger the contact area between the plastic film and cellulose paper laminate and the metal roll, the better. It should be noted that if the metal roll is held at a temperature above the melting point of the thermoplastic plastic, the thermoplastic plastic film and the cellulose paper will be sufficiently fused, so it is not necessary to hold the metal roll at a very high temperature.

In the method of the present invention, the thermoplastic plastic film refers to T-dyed thermoplastic plastics such as polyolefins such as polyethylene and polypropylene, as well as fluorine-based polymers such as polytetrafluoroethylene and fluoroethylene/fluoropropylene copolymers. This is a film formed by extrusion, inflation extrusion, etc.

Next, the present invention will be explained with reference to Examples and Comparative Examples.

Example 1 Polypropylene film (melting point 171°C, thickness 80°C)
Cellulose paper with a thickness of 40 μ is superimposed on both sides of the laminate, and then this laminate is introduced into two heated metal rolls with a roll gap of 10 cm, a roll diameter of 40 cm, and a surface temperature of 190°C, and one side of the laminate is One surface of the film is brought into pressure contact with the surface of a first roll and the cellulose paper is thermally fused, and then the other surface is brought into pressure contact with the surface of a second roll to bond the other surface of the film and the cellulose paper. A laminated paper was produced by heat-sealing it with cellulose paper. On this occasion,
In each of the first and second rolls, these rollers are arranged so that the laminate is wrapped around and in contact with about half of the roll surface, and the laminate is run at a linear speed of 50 m/min. A laminated paper, which is an adhesive between the film and the cellulose paper, was produced.

Examples 2 and 3 In Example 2, polytetrafluoroethylene film (melting point 330
In Example 3, a polyethylene film (melting point 135°C, thickness 80μ) was used, and the roll surface temperature was 360°C and 150°C, respectively. A laminated paper was produced.

Example 4 Polypropylene film (melting point 171°C, thickness 80°C
Cellulose paper with a thickness of 40 μ is superimposed on both sides of the laminate, and then this laminate is introduced into three heated metal rolls with a roll gap of 5 cm, a roll diameter of 30 cm, and a surface temperature of 190°C, and one side of the laminate is One surface of the film is brought into contact with the surface of a first roll and the cellulose paper is thermally fused, and then the other surface is brought into contact with a second roll to bond the other surface of the film and the cellulose paper. A laminated paper was produced by heat-sealing the film and the cellulose paper, and then bringing one surface of the film into contact with the surface of a third roll to further heat-seal the other surface of the film and the cellulose paper. At this time, the first, second, and third rolls were arranged so that the laminate was in contact with about half of the roll surface, and the rolls were run at a linear speed of 50 m/min. The laminate was run to produce a laminate paper which was a bond between the film and the cellulose paper.

Comparative example 1 Polypropylene film (melting point 171℃, thickness 80℃
40μ thick cellulose paper is placed on both sides of the paper, and then rolled with a roll diameter of 40cm at a surface temperature of 190℃.
A laminated paper was produced by introducing the film into a gap between two metal rolls at a temperature of 0.degree. At this time, the above-mentioned film and the above-mentioned cellulose paper were moved and brought into pressure contact with each other at a running linear speed of 2 m/min.

Comparative Example 2 The linear velocity of film and cellulose paper was set to 10
A laminated paper was produced in the same manner as in Comparative Example 1 except that the speed was set at m/min.

As a result of measuring the adhesive strength between the plastic film and cellulose paper for each of the laminated papers obtained in the above Examples and Comparative Examples, Examples 1 to 4
Comparative Example 1 and Comparative Example 1 both showed good adhesive strength of 300 to 500 g/15 mm width, but Comparative Example 2
It showed extremely poor adhesive strength of 10-30 g/15 mm width. Further, the laminated papers obtained in Examples 1 to 4 had good wrinkle-free surfaces, but the laminated papers obtained in Comparative Examples 1 and 2 had wrinkles.

As described above, the method of the present invention has made it possible to manufacture laminated paper with good adhesive strength with high productivity.

[Brief explanation of the drawing]

FIG. 1 is a schematic partial cross-sectional view showing an example of a conventional method for manufacturing laminated paper, and FIG. 2 is a schematic partial cross-sectional view showing an embodiment of the method for manufacturing laminated paper of the present invention. 1...Thermoplastic plastic film, 2,
2'...Cellulose paper, 3,3'...Metal roll.

Claims (1)

[Claims] 1. Cellulose paper is laminated on both sides of a thermoplastic plastic film that is not in a molten state, and then a plurality of sheets using this laminate are maintained at a temperature higher than the melting point of the thermoplastic plastic film that is not in a molten state. When manufacturing a laminated paper by bringing the film into contact with a metal roll to melt the film and heat-sealing it to the cellulose paper, the plurality of metal rolls are separated by a gap larger than the thickness of the laminated paper to be manufactured. production of laminated paper, characterized in that the laminate is passed between the metal rolls in a meandering manner so that one side and the other side of the laminate are alternately pressed into contact with each of the metal rolls and heat-sealed to the metal rolls. Method.