JPH03128223A - Manufacture of thermoplastic synthetic resin sheet - Google Patents

Abstract

PURPOSE:To uniformize the widthwise separation of sheet from roll by a method wherein a stripping roll, the peripheral speed of which is larger than that of forming rolls and which acts as a cooling roll, is provided at the position, at which the sheet drawn out of the forming roll leaves it, of the forming roll. CONSTITUTION:A sheet, which is extruded from an extruder 1 and is under molten state, is still under the state having elevated temperature at the stage being separated from a No.3 roll 2c, even being cooled somewhat by being passed through three rolls 2 acting as cooling rolls. Accordingly, a stripping roll acting as a cooling roll is provided at the position, at which the sheet drawn out of the No.3 roll 2c leaves it, of the No.3 roll 2c so as to nip the sheet in order to improve the adhesion of the sheet to the No.3 roll, resulting in improving the cooling effect of the No.3 roll and making the widthwise separation of the sheet cause to develop at equal position.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a thermoplastic synthetic resin sheet with excellent flatness.

<Prior Art> When producing a thermoplastic synthetic resin sheet, the resin is usually extruded in a molten state, passes through forming rolls such as a triple roll, and then is cooled and wound up as a solid sheet under constant tension.

<Problem to be solved by the invention> However, in that case, the resin that has been extruded in a molten state and passed through the three-roll N11L30-roll (see Figure 1) is still in a high temperature state, but both sides of the sheet are Since the cooling is faster, the sheet temperature is lower, and the peeling from the holes is faster.

If the peeling of the sheet from the roll is uneven in the width direction as described above, (1) the tension in the width direction becomes uneven, resulting in distortion of the sheet and warpage, etc.;

■ Because the peeling position is unstable, subtle vibrations occur and the sheet surface wanders.

This inconvenience occurs, especially when the sheet molding conditions are changed.

<Means for Solving the Problems> The present invention solves the above problems by installing a so-called peeling roll, which has a higher circumferential speed than the forming roll and is a cooling roll, at the sheet pull-out contact point of the forming roll. This can be achieved by

The present invention will be explained in more detail below.

As the thermoplastic resin used in the present invention, polyolefins such as polyethylene and polypropylene, as well as polystyrene, polyester, polyamide, etc., can be used, as long as they are generally molded into a sheet. The sheet here has a thickness of 0.5 to 1011111%, preferably 0.6 to 111%.
I'm talking about 6mm.

Hereinafter, explanation will be made according to the drawings. Figure 0-1 is a diagram showing one embodiment of the present invention, and the explanation of each number is as follows.

1, Extruder 2, Sheet molding machine (three rolls) 2a: Fhl roll, 2b: 20-roll, 2C: Asahi 30
- Roll 3, Peeling roll (cooling roll) 4, Guide roll 5, Recoiler 6, Thermoplastic synthetic resin sheet extruder (The molten sheet extruded from 11 passes through the cooling roll (2) Although it cools down somewhat during the process, it is still at a high temperature when it is peeled off from the 30-rule (2c).At this time, the surface of the sheet that was in contact with the 30-rule (2c) is exposed to the outside due to heat conduction. The sides of the sheet that were in contact with the air are cooled faster than the sides that were in contact with the air.Also, in the width direction of the sheet, both sides are cooled faster than the center.If the sheet is pulled under tension while the sheet temperature is uneven in this way, As mentioned above, problems arise in that the sheet becomes distorted and its flatness deteriorates.

Therefore, a peeling roll (3), which is a cooling roll, is installed at the contact point for drawing out the sheet from the Tane 30-ru (2C), and by nipping the sheet, it improves the adhesion of the sheet to the Hiro 30-Rule and improves the cooling effect. It is possible to perform peeling at a uniform position in the width direction of the sheet.

Furthermore, by cooling the sheet from both sides, the sheet surface can be made glossy at the same time.

In addition, conventionally, a certain amount of tension was required on the sheet in order to peel it off from the peeling roll (3).
The roll is forcibly driven, and by making the circumferential speed slightly higher than that of 30 mm, the sheet can be peeled off very smoothly over 30 mm. The peripheral speed of the peeling roll should be 0.02 to 2% faster than the peripheral speed of the Hiro 30-ru, preferably about 0.05 to 0.5%. If the peeling roll is too fast compared to the 1lh 30-ru, the sheet may There is a difference in elongation on both sides, which is undesirable as it causes distortion.

The size of the diameter of the peeling roll is not particularly specified, but the smaller the diameter than the three rolls (2a, 2b, 2c), the greater the effect.Specifically, the diameter of the three rolls (Hiroshi 30-)
It is preferably about 1/2 to 1/3 of the diameter of the tube.

Since the sheet temperature is near the melting point, it is preferable not to apply more pressure than necessary with the peeling roll, since applying too much pressure will affect the sheet thickness.

That is, the linear pressure is preferably about 1 to 10 kg/cs+, although it varies depending on the material, temperature, and thickness of the sheet.

Like the three rolls, the peeling roll has a hard chrome plated surface with a mirror finish, and the temperature is controlled by circulating a heating medium such as cold water, hot water, or heated oil inside the roll.The temperature of the peeling roll is determined by the sheet thickness, Extrusion amount (sheet speed)
Although it varies depending on the temperature, the temperature is usually set in the range of 40 to 80°C when low density polyethylene is used. (The surface temperature of the sheet at this time is about 100 to 140°C.) The sheet thus pulled out from the three-roll roll and the peeling roll is cooled in a conventional manner and transferred to an uncoiler as a solid sheet. It is wound up in (5).

<Effects of the Invention> As described above, the thermoplastic synthetic resin sheet obtained by the method of the present invention is free from distortion and has good surface properties.

This is a conceptual side view showing the following numbers.

■...Extruder, 2...Sheet forming machine (three rolls)
, 3...'JIWI roll (cooling roll), 4...
Guide roll, 5... Recoiler, 6... Thermoplastic synthetic resin sheet.

Claims (1)

[Claims] (1) In a method of manufacturing a solid thermoplastic synthetic resin sheet by extruding a thermoplastic synthetic resin in a molten state between forming rolls and taking it off while cooling, the peripheral speed is higher than that of the forming roll at the sheet drawing contact point of the forming roll. A method for producing a thermoplastic synthetic resin sheet characterized by installing a certain cooling roll