JPH04276426A - Manufacture of polymer sheet - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing efficiently a polymer sheet with a thickness of 5mm or thicker and high accuracy of the thickness. CONSTITUTION:A polymer material heated, kneaded and extruded by using an apparatus wherein an extruder 2, a die having a temp. control apparatus and a rolling mill are continuously arranged is calendered by means of rolls while it is kept at a const. temp. just below the m.p. As ununiformity of the thickness can be corrected by means of roll calendering, it is possible to make the extrusion speed higher than that for the conventional method. In addition, it is possible to make selectively sheets in a wide range of thickness by using one die by adjusting the distance between rolls.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for manufacturing sheets of polymeric materials.

0002

[Prior art] Conventionally, thick plastic sheets (
(usually 5 mm or more) are manufactured using a hot extruder. This manufacturing method is as shown below. That is, as shown in FIG. 2, the polymer material supplied as pellets to the hopper 1 is continuously extruded by an extruder 2 that heats and kneads the pellets, and is mixed into a die 3. The die 3 is cooled with water, and the polymer material mixed in in a molten state cools and solidifies as it moves through the die, becomes completely solid near the die exit, and exits the die 3 as a sheet 4. go. However, in these methods, there are still problems to be solved in terms of productivity and the like.

0003

[Problems to be Solved by the Invention] In the extrusion manufacturing process described above, the shape of the sheet is created while the polymer material passes through the die, and the polymer material has a large shape before it reaches the exit of the die. , it is necessary to solidify it sufficiently. Therefore, the temperature of the polymeric material must be lowered from above its melting point to room temperature before reaching the die exit. However, since the thermal conductivity of polymeric materials is much higher than that of metals, they do not cool easily, making it difficult to manufacture sheets with a thickness of 5 mm or more at high speed. Furthermore, in the conventional method, it was necessary to replace the die each time the thickness of the sheet was changed, resulting in extremely low productivity. In view of the above points, the present invention aims to provide a method for efficiently manufacturing a polymer sheet having a thickness of 5 mm or more and having high thickness accuracy.

0004

[Means for Solving the Problems] The gist of the present invention is to continuously arrange an extruder, a die having a temperature control device, and a rolling mill to heat, knead, and extrude a polymer material at a constant temperature. A method for producing a polymer sheet, characterized by rolling the sheet while holding the sheet at

[0005] The present invention will be explained in detail below based on the drawings. First, as a result of many experiments, the inventors found that in hot extrusion of polymers, the die temperature greatly affects the die exit speed of the sheet. As a result of more detailed experiments, we found that, as shown in Figure 3, if the die temperature is kept just below the melting point, the plate thickness accuracy deteriorates, but the speed is several times faster than the conventional method in which the die temperature is kept at room temperature. , it was discovered that sheets could be manufactured. Figure 3 shows polypropylene (PP)
) with sheet dimensions of 20t x 300W. In other words, if it is possible to correct the sheet thickness in a post-process, it becomes possible to manufacture sheets at several times the efficiency of conventional methods.

[0006] Therefore, the inventors searched for a method of correcting the sheet shape and discovered that rolling with rolls is effective. FIG. 4 shows the thickness distribution in the width direction of sheets manufactured by the conventional method (hot extrusion method) and the present invention (method of rolling with rolls after high-speed hot extrusion). From this result, it was found that even if the thickness accuracy deteriorates due to high-speed extrusion, if the sheet is straightened by rolling with rolls, it is possible to produce a sheet with better thickness accuracy than the conventional method.

Furthermore, the inventors have discovered that by adjusting the gap between the rolls during rolling, a sheet of any thickness within the range shown in FIG. 5 can be obtained. For example, if the sheet thickness at the die exit is 50 mm, 10
The plate thickness can be adjusted in the range of ~50mm. Therefore, by using this method, it is possible to manufacture sheets with a wide range of thickness without changing the die.

[0008] Thus, the present invention can efficiently produce a polymer sheet with high plate thickness accuracy.

FIG. 1 shows the manufacturing method of the present invention. The equipment used in this manufacturing method is mainly an extruder 2, a constant temperature die 3, and a rolling roll 5. In the extruder 2, polymer pellets are heated and kneaded, and mixed into the die 3, as in the conventional process. In the present invention, the die 3 is kept at a temperature just below its melting point. In the die 3, the molten polymer is cooled to just below its melting point (at this stage, the surface of the polymer material is slightly hardened, but the inside is in a plastic state), and is sent to the die exit. Finally, the polymer sheet is rolled by the roll 5 to adjust its shape and thickness. Note that, in order to prevent deterioration of the surface properties of the sheet, the roll may be heated with an internal heater or the like.

0010

[Example] Example 1 PP die of 20 mmt x 300 mmW (die temperature: 1
50° C.) at a speed of 150 mm/min. Immediately after that, the manufactured sheet is rolled into 10
It was rolled to mmt. As a result, the exit sheet speed is 300
mm/min (with the conventional method, the maximum speed is 50 mm/min
), it was possible to produce a sheet with excellent surface properties. The plate thickness accuracy was also equal to or better than that of conventional materials.

Example 2 A PE die of 20 mmt x 500 mmW (die temperature: 1
30° C.) at a speed of 150 mm/min. Immediately after that, the manufactured sheet is rolled into 10
It was rolled to mmt. As a result, the exit sheet speed is 300
mm/min (with the conventional method, the maximum speed is 50 mm/min
), it was possible to produce a sheet with excellent surface properties. The plate thickness accuracy was also equal to or better than that of conventional materials.

Example 3 Fiber-reinforced PP (carbon fiber 20wt%) 20mmt×3
1 using a 00mmW die (die temperature: 150℃)
It was extruded at a speed of 50 mm/min. Immediately after that,
The produced sheet was rolled to a thickness of 10 mm. As a result, it was possible to produce a sheet with excellent surface properties at an exit sheet speed of 300 mm/min (in the conventional method, the maximum speed was 40 mm/min). The plate thickness accuracy was also equal to or better than that of conventional materials.

Example 4 A PP die of 10 mmt x 300 mmW (die temperature: 1
50° C.) at a speed of 150 mm/min. Immediately after that, the manufactured sheet was rolled for 5 m.
It was rolled to mt. As a result, the exit sheet speed was 300 m.
m/min (with conventional method, maximum 50 mm/min)
This made it possible to produce a sheet with excellent surface properties. The plate thickness accuracy was also equal to or better than that of conventional materials.

Example 5 A PP die of 50 mmt x 500 mmW (die temperature: 1
50° C.) at a speed of 50 mm/min. Immediately after that, the manufactured sheet was rolled for 40 m.
It was rolled to mt. As a result, the exit sheet speed was 63 mm.
/min (in the conventional method, the maximum speed is 50 mm/min), and a sheet with excellent surface properties could be produced. The plate thickness accuracy was also equal to or better than that of conventional materials.

[0015] Comparative example PP was used in a die of 10 mmt x 300 mmW (die temperature: 2
0° C.) at an exit sheet speed of 150 mm/min, but since the temperature did not drop sufficiently, only sheets with poor shapes could be produced. Under these conditions, in order to obtain a good sheet, the speed must be set to 50 mm/mi.
It was necessary to lower it to n.

[0016]

[Effects of the Invention] According to the present invention, it has become possible to efficiently produce a polymer sheet with high thickness accuracy at any thickness.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the manufacturing process in the present invention.

FIG. 2 is an explanatory diagram of a conventional method for manufacturing a polymer sheet (hot extrusion method).

FIG. 3 is a chart showing the range of sheet speeds at which sheets can be manufactured at each die temperature.

FIG. 4 is a chart comparing plate thickness accuracy between the conventional method and the present invention.

FIG. 5 is a chart showing the sheet thickness that can be manufactured with one die in the present invention.

[Explanation of symbols]

1 Hopper 2 Extruder 3 Constant temperature die 4 Polymer sheet 5 Rolling roll

Claims (1)

[Claims] Claim 1: A polymeric material comprising an extruder, a die having a temperature control device, and a rolling mill, which are successively arranged to roll the heated, kneaded, and extruded polymeric material while maintaining it at a constant temperature. Method for manufacturing molecular sheets.