JPS5827089B2 - Fusion lamination method for thermoplastic resin sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for fusing and laminating thermoplastic resin sheets.

It is known to laminate thermoplastic sheets or foamed sheets thereof with other sheets using adhesives.

However, the solvent in the adhesive has the property of dissolving the resin, and thermoplastic resin sheets or their foam sheets do not have air permeability or liquid permeability, so it is difficult to remove the solvent, and it is difficult to remove the solvent over the entire surface of the sheet. It is also difficult to adhere uniformly.

It is also known to heat thermoplastic resin sheets to melt their surfaces and laminate them.

However, conventionally, the surface of the thermoplastic resin sheet to be melted is heated at a certain distance from a heat source such as an infrared heater.
In order to melt the sheet, it takes time to heat and melt the sheet, making it impossible to quickly fuse the sheet, and particularly in the case of a foamed sheet, there is a drawback that the thickness of the sheet is reduced.

The present inventor has improved the above-mentioned drawbacks, efficiently heat-seals other sheets to a thermoplastic resin sheet or a thermoplastic resin foam sheet, and obtains a laminated sheet that is completely fused and has no unevenness in fusion. As a result of intensive research, we have completed the present invention.

In the present invention, a thermoplastic resin sheet and a sheet to be heat-sealed thereto are directly brought into contact with the surfaces of two rod-shaped heating elements each having a length that is equal to or slightly longer than the width of the thermoplastic resin sheet. The gist of the present invention is a method for fusing and laminating thermoplastic resin sheets, which is characterized in that a laminated sheet is obtained by pinching and fusing with a pair of nip rolls immediately after heating.

The thermoplastic resin sheet used in the method of the present invention is a sheet of polystyrene, polyethylene, polypropylene, polyvinyl chloride, a copolymer resin of these resins, a mixed resin sheet, or a foamed sheet of pine resin of these resins.

Examples of the sheet to be heat-sealed to the thermoplastic resin sheet include paper, cloth, nonwoven fabric, and the thermoplastic resin sheet described above.

The heating element used in the method of the present invention is preferably a glass tube containing a nichrome wire or a cartridge heater, and has a length that is the same as or slightly longer than the width of the thermoplastic resin sheet to be fused. Those having the following are used.

In addition, the cross-sectional shape of the heating element is circular or oval,
Particularly suitable is one having an elliptical cross section and arranged so that its axial angle can be changed.

This makes it possible to control the heating and melting of the thermoplastic resin sheet by changing the surface area of the heating element that comes into contact with the thermoplastic resin sheet.

Further, it is preferable that the two heating elements are heated separately and that the temperature can be adjusted to an appropriate temperature using, for example, a slidex.

In the method of the present invention, the surface of the thermoplastic resin sheet is brought into direct contact with the surface of the heating element and heated to a temperature equal to or higher than the melting temperature of the thermoplastic resin sheet.

Therefore, the surface of the thermoplastic resin sheet that comes into contact with the heating element melts, but since the thermoplastic resin sheet is guided at a constant rate, the heating time is instantaneous, and the thickness of the thermoplastic resin sheet that is melted is extremely small. stomach.

If the sheet to be fused to the thermoplastic resin sheet is a similar thermoplastic resin sheet, it can be heat-fused and laminated by heating in the same manner as described above.

When the sheets to be laminated are paper, cloth, or nonwoven fabric, it is desirable to heat them to a higher temperature than the heating of the thermoplastic resin sheets to promote fusion.

The surface of the thermoplastic resin sheet melts depending on the heating temperature of the heating element.
In relation to the induction speed of the thermoplastic resin sheet, the induction speed of the thermoplastic resin sheet can be increased by increasing the heating temperature of the heating element.

If the heating temperature is low and the induction speed is fast, sufficient fusion will not be obtained; conversely, if the heating temperature is high and the induction speed is slow, the thermoplastic resin sheet will melt a lot, and especially in the case of foam sheets, the thickness There is a risk that the elasticity will decrease, turn into resin, and lose elasticity.

Generally, it is preferable to fuse the laminated sheets to such an extent that they do not easily peel off.

For example, when a polystyrene foam sheet is used as the thermoplastic resin sheet and paper is used as the sheet to be fused to the sheet, the heating element in contact with the thermoplastic resin sheet is
~400゛C, the heating element in contact with the paper about 500~600℃
A good laminated sheet can be obtained by heating to 0.degree. C. and guiding and fusing at a speed of about 25 to 35 meters per minute.

In addition, when using a polystyrene sheet instead of the paper described above, it depends on the thickness of the sheet, but generally a heating element in contact with the surface of the polystyrene sheet is heated to about 400 to 500°C, and the same procedure as above is performed. A well-fused laminated sheet can then be obtained.

Next, the method of the present invention will be explained with reference to the drawings.

The drawings are schematic diagrams illustrating the invention in detail.

In FIG. 1, 1 is a polystyrene foam sheet and 2 is kraft paper.

3 and 4 are infrared heaters, which are rod-shaped heating bodies made of quartz glass tubes with built-in nichrome wires and whose length is slightly longer than the width of polystyrene foam sheet 1 and kraft paper 2, and whose cross section is oval. It shows.

Infrared heater 3 in contact with polystyrene foam sheet 1
is heated to about 400°C, and the infrared heater 4 in contact with the kraft paper 2 is heated to about 600°C.

The polymethic foam sheet 1 and the kraft paper 2 are guided through guide rolls 5 into contact with infrared heaters 3 and 40, respectively.

Reference numeral 6 denotes a control roll that lightly presses the polystyrene foam sheet 1 and the kraft paper 2 so that the polystyrene foam sheet 1 and the kraft paper 2 come into good contact with the surfaces of the infrared heaters 3 and 4.

1 is a pair of nip rolls.

The polystyrene foam sheet 1 is brought into contact with the infrared heater 30 surface and melted, and the melted surface is overlapped with the kraft paper 20 surface heated by the infrared heater 4 and pressed by the nip rolls 7 to form the laminated sheet 8. formed.

In order to complete the fused lamination of the polystyrene foam sheet 1 and the kraft paper 2, it is desirable to operate the nip roll 7 while heating it to a temperature above room temperature, that is, 40 to 90°C.

By winding up the laminated sheet 8 on a take-up roll at a speed of about 30 m per minute under the above conditions, a sufficiently fused laminated sheet can be obtained.

FIG. 2 shows another example, illustrating a method of heat-sealing and laminating a polyethylene foam sheet 11 and a polyethylene sheet 12.

The infrared heater 4 that is in contact with the surface of the polyethylene sheet 120 is in contact along the long axis direction of the elliptical cross section, but the infrared heater 3 that is in contact with the surface of the polyethylene foam sheet 11 is in contact along the short axis direction. It's forcing me.

By changing the axial direction of the ellipse in this manner, the melting state of the rate can be changed.

That is, by bringing the polyethylene foam sheet 110 into contact along the minor axis direction of the infrared heater, the heating time is shorter than when bringing the polyethylene foam sheet 110 into contact with the infrared heater in the major axis direction, and therefore the thickness of the sheet to be melted is less.

In conjunction with adjusting the heating temperature of the infrared heaters 3.4 and the take-up speed of the laminated sheet 13, the axial direction of the ellipse of the infrared heaters 3 and 4 is changed to heat-seal the thermoplastic resin sheet and this. The heating and melting state of the sheet can be changed freely.

In the method of the present invention, as described above, the thermoplastic resin sheet and the surface of the sheet to be heat-sealed are brought into direct contact with separate Q heating elements and heated by induction, so the heating is instantaneous. Only the thermoplastic resin sheet and the surface layer of the sheet to be thermally fused thereto are heated, and the surface of the molten thermoplastic resin sheet is immediately pressed and fused by a pair of nip rolls 7.

Therefore, thermal efficiency is extremely high, the thermoplastic resin sheet is not melted more than necessary, and the thickness of the laminated sheet is less reduced, especially in the case of a foamed sheet.

For example, when polystyrene foam sheets are laminated using the conventional thermal method, the thickness is reduced by 40 to 50% from the original thickness.
According to the method of the present invention, the thickness reduction is within 20%.

In the method of the present invention, the thermoplastic resin sheet and the sheet to be fused thereto are heated using separate heating elements, so each can be heated to a desired temperature separately. Since the shape is elliptical and the heating and melting state can be adjusted by rotating the axial direction to change the contact area, a good laminated sheet can be easily obtained.

Furthermore, compared to the conventional thermal fusion method, the method of the present invention is extremely efficient because it can perform thermal fusion at a high speed.

Furthermore, since no adhesive is used in the method of the present invention, there are no problems such as dissolution of the resin by a solvent, removal of the solvent, etc., and a uniformly fused, high-quality laminated sheet can be obtained.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are schematic explanatory diagrams showing the method for fusing and laminating thermoplastic resin sheets of the present invention. The main symbols in the drawings are as follows. 1...-polystyrene foam sheet, 2...
・Kraft paper, 3°4...°...Infrared heater, 5
...Guide roll, 6...Adjustment roll, 7...
Nitsuprol, 8, 13... Laminated sheet, 11
...Polyethylene foam sheet, 12...-
・Polyethylene sheet.

Claims (1)

[Claims] 1. A thermoplastic resin sheet and a sheet to be heat-sealed to the thermoplastic resin sheet are separately and directly placed on the surfaces of two rod-shaped heating elements each having a length that is equal to or slightly longer than the width of the thermoplastic resin sheet. A method for contact lamination of thermoplastic resin sheets, which is characterized in that a laminated sheet is obtained by bringing the sheets into contact and guiding them, and then immediately after heating, clamping them with a pair of nip rolls and fusing them to obtain a laminated sheet. 2. The method of fusing and laminating thermoplastic resin sheets according to claim 1, wherein the heating element has an elliptical cross-sectional shape and its axial angle with respect to the sheet is variable. 3. Claim 1, wherein the surface of the heating element is heated to a temperature higher than the melting temperature of the thermoplastic resin sheet, and the two heating elements are heated to different temperatures. A method for fusion lamination of thermoplastic resin sheets. 4. The thermoplastic resin sheet according to claim 1, wherein the thermoplastic resin sheet is a sheet of polystyrene, polyethylene, polypropylene, polyvinyl chloride, a copolymer resin of these resins, a mixed resin sheet, or a foamed sheet. Fused lamination method. 5. The method for fusing and laminating thermoplastic resin sheets according to claim 1, wherein the sheet to be heat-sealed to the thermoplastic resin sheet is paper, cloth, nonwoven fabric, a thermoplastic resin sheet, or a foamed sheet thereof. 6. The method for fusing and laminating thermoplastic resin sheets according to claim 1, wherein the nip rolls are heated to 40 to 90°C and the laminated sheets are clamped and pressed.