JPH09267460A - Method for laminating thermoplastic resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet laminating method capable of setting preheating temperature at a necessary minimum level to dissolve dimensional inferiority caused by heat deformation or the like by continuously laminating the sheets with a thermocompression bonding roll immediately after preheating two or more thermoplastic resin sheets to softening temperatures or higher of respective resins with infrared rays. SOLUTION: Just after preheating at least two or more thermoplastic resin sheets to softening temperatures or higher of respective resins with infrared rays, the sheets are continuously laminated with a thermocompression bonding roll. Concretely, two sheets (a) and (b) consisting of thermoplastic resin are sent out from the feed rolls 1, 1', and directly preheated with a heater 3 equipped with an infrared heater provided just before the thermocompression bonding roll 2. Then, the sheets (a) and (b) are inserted into the roll 2 from an insertion point 4 of the roll 2 immediately after preheating (within 1.0s) to carry out thermocompression bonding. Thereby, a required laminate 5 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously laminating sheets made of a thermoplastic resin, and more particularly to a surface having a colored layer such as a windshield sheet, an exterior, an interior surface material, etc. on which a hard coat layer is laminated. The present invention relates to a method for laminating thermoplastic resin sheets (hereinafter abbreviated as sheets) used as exterior decorative materials, interior surface materials, display surface materials, and the like.

[0002]

2. Description of the Related Art When sheets are continuously laminated, the sheets are preheated by using a preheating roll and then laminated by a thermocompression bonding roll. The preheating of the sheet in this way is for uniformly inserting the pressed product as a sheet into the thermocompression-bonding roll, and in the case of laminating a large number of sheets, the contact between the layers before the insertion of the thermocompression-bonding roll is performed between the layers. This is to make it tight so that air does not enter, and if the sheet is inserted into a thermocompression roll without being preheated uniformly in the width direction, wrinkles are generated or air is mixed. From such a point, in the conventional method, for example,
As shown in FIG. 2, each of the feed rolls 11 and 11 '
The two sheets a and b sent out from the sheet are preheated by respective preheating rolls 13 and 13 ', and the sheets a and b are inserted into the insertion point 14 of the thermocompression bonding roll 12 in the next step, The laminated body 15 is obtained according to need.

[0003]

However, when laminating by the above-mentioned conventional method, the roll 13 for preheating,
Since the distance from 13 'to the insertion point 14 is long and the sheets are cooled by the time of stacking, it is necessary to set the temperature of the roll for preheating considerably higher than the heat softening temperature of the sheet material. There is a problem in that thermal deformation occurs, neck-in and the like occur, and defects due to dimensional changes occur. In addition, because it uses a roll for preheating, there is a drawback that the sheet is difficult to peel off from the roll due to the heat fusion phenomenon of the contact surface because it is preheated by directly contacting the sheet, causing peeling trouble, compatibility with metal roll In the case of a material that is difficult to peel off with, it will stick to the roll, if you try to forcefully peel it, the material will stretch significantly, and if the surface is processed with printing ink etc., the ink Is transferred to the surface of the metal roll, fused, adhered, and stained. Furthermore, because it is a preheating method by surface contact, it is easily affected by the state of the surface of the roll for preheating, and the unevenness of the material is poor and variations occur if not evenly contacted,
The unevenness of the surface has a great influence, and there is a problem that it is very difficult to control these processing.

The present invention solves the above-mentioned conventional problems, in which the preheating temperature can be set to the minimum necessary temperature, dimensional defects such as thermal deformation are eliminated, and peeling troubles and An object of the present invention is to provide a sheet stacking method capable of uniformly preheating as a whole without heating unevenness of an object to be heated.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have replaced the conventional sheet preheating by direct contact with a preheating roll with
By carrying out non-contact preheating using infrared rays or far infrared rays under specific conditions, a sheet lamination method which is extremely desirable for practical use was found, and the present invention was completed. That is,
The gist of the present invention is a method for laminating a sheet in which at least two sheets are preheated with infrared rays to a temperature not lower than the thermal softening temperature of each resin and then the sheets are immediately and continuously laminated with a thermocompression roll.

The sheet laminating method of the present invention will be described in detail below. The sheet used in the method of the present invention is
It is made of a thermoplastic resin such as vinyl chloride resin, polyethylene, polypropylene, polystyrene, or polyvinyl acetate, and its thickness is not particularly limited as long as it can be used as a laminate, but is usually 0.02 2.0 mm
It is a degree. This sheet is sent out from different feed rolls, and it is important to preheat the sheet directly by infrared rays immediately before these sheets overlap each other. This preheating means is performed by an infrared heater or a far infrared heater provided in the heater, and is usually heated by about 3250 W / 220 V to preheat each sheet. The infrared rays used in the present invention have a wavelength in the range of 0.75 μm to 400 μm, more preferably far infrared rays, and the wavelength thereof is 6 μm to 400 μm.
When the wavelength range is shorter than 0.75 μm, the infrared ray transmission is increased and the infrared rays pass through the sheet to reduce the heating effect. On the other hand, if it is longer than 400 μm, the energy of infrared rays is reduced, resulting in inefficiency, and in any case, the loss increases. Although the preheating conditions vary depending on the type of resin used, it is necessary to preheat the sheet to a temperature above the heat softening temperature of each resin. For example, when the sheet is made of vinyl chloride resin, the sheet temperature is set in the range of about 50 to 80 ° C, and when it is made of polyethylene, the sheet temperature is set in the range of about 45 to 55 ° C. Good.

The heater used in the present invention preheats by utilizing the principle of radiant heating. As the heat source,
It is performed with infrared rays by electric heating. As this heating device, a device using ceramic as a medium is generally used, and its shape is a rod-like shape or a shape close to this so that it can be heated over the entire width of the sheet and as short as possible in the length direction. Things are used. The sheet may be preheated by a heating device by preheating only one side of the sheet or by both sides.When preheating both sides, a heating device is installed on each side of the sheet. You can do it. Further, in order to enhance heating efficiency and spot heating, a heater provided with a heat reflection plate may be installed as necessary, and there is no particular limitation as long as it is intended to improve preheating.

Next, in the present invention, the respective sheets are preheated, and immediately thereafter, they are thermocompression-bonded from the insertion point of the thermocompression-bonding roll to laminate the sheets. The term "immediately" as used herein means that thermocompression bonding is performed within 1.0 second after preheating. The thermocompression-bonding roll used in the present invention is for inserting and stacking the respective sheets, and is usually a pair of upper and lower, and the gap or contact position serves as an insertion point from which the sheet is inserted. Then, the sheets are laminated. In this thermocompression-bonding roll, the roll to be pressure-bonded from the upper part is usually made of silicone, and the lower heating drum is made of stainless steel, and the temperature is adjusted to about 140 to 170 ° C. to perform the thermocompression bonding of the sheet. In the present invention, the number of sheets to be laminated is usually two, but three, four or more sheets can be applied. In that case, a feed roll may be additionally provided for thermocompression bonding. The combination of sheets to be laminated may be the same or different as long as they are thermoplastic resins, and a desired laminated body can be obtained according to need.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an explanatory view showing an example of the sheet stacking method of the present invention. As shown in this figure, two sheets a and b made of a thermoplastic resin are used.
Are fed from the respective feed rolls 1, 1 ′ and directly preheated by a heater 3 equipped with a far infrared heater provided immediately before the thermocompression bonding roll 2, and the roll 2 from the insertion point 4 of the thermocompression bonding roll 2. Sheets a and b are inserted into and crimped to obtain a desired laminated body 15.

[0010]

Next, examples and comparative examples of the present invention will be described. (Example 1) A thickness of 0.2 m was obtained by the method shown in FIG.
m, 1300 mm wide vinyl chloride resin clear sheet (Shin-Etsu Polymer Co., Ltd. product name “Shinetsu Clear Sheet”) and 0.4 mm thick, 1300 mm wide vinyl chloride resin printing sheet (Shin-Etsu Polymer Co., Ltd. product name “ Shin-Etsu Clear Sheet ”) was laminated. The preheating condition is the infrared heater BBSG375 installed in the heater.
No. 0 (trade name, manufactured by Heraeus) was used to heat at a wavelength peak value of 12.0 μm and 3250 W / 220 V, and the temperature of each sheet was set to 50 ° C. Next, the heating temperature at the time of lamination was set to 155 ° C., and immediately (0.5 seconds after maximum proximity preheating), each sheet was thermocompression bonded, and finally the temperature of the embossing roll was adjusted to 6
A desired laminate was obtained by pressing at 0 ° C. and a pressure of 3 kg / cm.

(Comparative Example 1) Using the same clear sheet and printing sheet as in Example 1, lamination was carried out by a method using a preheating roll shown in FIG. The preheating conditions were set so that the sheet temperature of the clear sheet was 40 ° C. and the sheet temperature of the printing sheet was 50 ° C. using a preheating roll (manufactured by Nishimura Koki Co., Ltd.). Then, the heating temperature at the time of lamination was set to 155 ° C., each sheet was thermocompression-bonded with a thermocompression-bonding roll, and finally the temperature of the embossing roll was set to 60 ° C. and pressed at a pressure of 3 kg / cm to obtain a desired laminate. .

(Comparative Example 2) Using the same clear sheet and printing sheet as in Example 1, lamination was carried out by a method using a preheating roll shown in FIG. The preheating conditions were set using a preheating roll (manufactured by Nishimura Koki Co., Ltd.) so that the sheet temperature of the clear sheet was 50 ° C and the sheet temperature of the printing sheet was 60 ° C. Then, the heating temperature at the time of lamination was set to 155 ° C., each sheet was thermocompression-bonded with a thermocompression-bonding roll, and finally the temperature of the embossing roll was set to 60 ° C. and pressed at a pressure of 3 kg / cm to obtain a desired laminate. . Table 1 shows the results of observing the neck-in width, the state of air entrainment, and the slack / slack of the laminates obtained in Example 1 and Comparative Examples 1 and 2. The neck-in width was measured by the difference between the sheet width before lamination and the sheet width after lamination, and air entrainment and deviation / slack were visually observed.

[0013]

[Table 1]

(Results) As is clear from the results shown in Table 1,
In the case of using the roll for preheating as shown in Comparative Examples 1 and 2, the change in the neck-in width was large, and defects such as entrainment of air and generation of slippage and slack were observed, but as shown in Example 1, With a simple infrared heater, the change in neck-in width is small, air entrapment,
Good results were obtained with no sagging.

[0015]

According to the method of the present invention, the steps from preheating to the insertion point can be continuously and quickly performed, so that the sheet can be preheated at the minimum required preheating temperature. The thermal deformation of the sheet when performed by the conventional method can be reduced. Further, since it is a method of preheating without directly contacting the sheet, troubles due to contact with the preheating roll can be eliminated. Furthermore, because it is preheated with infrared rays, there is no uneven heating due to the shape of the object to be heated,
Since the entire sheet can be uniformly preheated, the quality control of processing is easy.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a stacking method of the present invention.

FIG. 2 is a schematic explanatory view showing a conventional laminating method.

[Explanation of symbols]

 1, 1 '... Feed roll 2, 12 ... Thermocompression bonding roll 3 ... Heating machine 4, 14 ... Insertion point 5, 15 ... Laminated body 11, 11' ... Feed roll 13, 13 '... Roll for preheating

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shigenobu Hiraiwa 1-406-1 Yoshino-cho, Omiya-shi, Saitama 1 Shin-Etsu Polymer Co., Ltd. Tokyo factory

Claims (1)

[Claims] 1. A thermoplastic resin characterized in that at least two thermoplastic resin sheets are preheated by infrared rays to a temperature above the heat softening temperature of each resin, and then the sheets are immediately and continuously laminated by a thermocompression-bonding roll. Sheet stacking method.