JPS6258284B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a calender molding method capable of obtaining a thermoplastic resin sheet with uniform thickness and good surface condition.

Conventionally, in the calender molding process of thermoplastic resins such as hard vinyl chloride, thickness fluctuations tend to occur in the width direction of the sheet, but this can be caused by various factors in addition to uneven calender roll gaps. , its adjustment is a difficult problem.

Further, in the calender sheet, uneven kneading of the resin tends to occur, and this uneven kneading also results in local thickness fluctuations (irregularities).

This unevenness in kneading has an adverse effect on the post-processing of the sheet (printing, lamination, etc.), but it has been extremely difficult to suppress it.

As a result of studies to solve the above-mentioned problems, the inventors of the present invention found that the fact that the sheet is not peeled off uniformly in the process of peeling the sheet from the final calender roll is one of the causes of thickness fluctuation in the width direction. We have learned that there are.

Then, by installing a tatsuchi roll on the take-off roll that takes up the sheet and taking it off while nipping the sheet, the sheet is pulled off evenly and the thickness fluctuation is improved. Then, they discovered that the unevenness of kneading could be reduced at the same time, and arrived at the present invention.

That is, the gist of the present invention is that in a method of calender-molding a thermoplastic resin sheet, a tatsuchi roll 3 is provided on the final roll 11 side on the first take-off roll 2 that peels the sheet from the final calender roll 11, and the sheet is After contacting the Tatsuchi Roll 3, while the sheet is still in a softened state, the Tatsuchi Roll 3 is placed on the take-off roll 2.
This calendar molding method is characterized by taking the sheet while nipping it.

The present invention will be explained in detail below.

FIG. 1 is a side view showing an example of an apparatus for carrying out the method of the present invention, in which 1 is a calender roll;
1 is a final calender roll (hereinafter referred to as the final roll), 2 is a take-off roll, 3 is a tatsuchi roll, and S is a sheet. Also, Figure 2 shows the sheet S
FIG. 1 is a view seen from the direction of FIG.

As the calender roll 1, various types of conventionally known types can be used. Takeoff roll 2
is also a conventional type, and rotates at a higher circumferential speed than the final roll 11, and stretches the sheet S while peeling it off from the final roll 11 and takes it off. The take-off roll 2 is a metal roll with a smooth surface, whose temperature is adjusted from the inside, and cools the sheet S.

The tatsuchi roll 3 is a freely rotating (non-driven) roll, the surface of which is coated with a smooth elastomer material, and is in light contact with the take-off roll 2.

The advantage of using the touch rolls 3 to nip the sheet S is, first, that the state in which the sheet S is peeled off from the final roll 11 is uniform and stabilized. That is, in the conventional method in which the touch roll 3 is not provided, the sheet S is peeled off in a state as shown by the dotted line A in FIG. 2, and as a result, the thickness of the sheet S differs between the center and the ends. In contrast, according to the method of the present invention, a uniform peeling state as shown by line B in FIG. 2 is obtained, and the thickness distribution in the width direction of the sheet S is made significantly uniform.

The second advantage is that the neck-in of the sheet S is reduced and the thickness distribution in the width direction is made uniform.

The third advantage is that by pressing the sheet S, unevenness caused by uneven kneading can be smoothed out, and surface protrusions such as fissures can be forced into the sheet S, resulting in printing and lamination with a good surface condition. A sheet suitable for such applications can be obtained.

In order to achieve these effects, it is important to provide the touch roll 3 as close as possible to the final roll 11 on the take-off roll 2 at a position where the sheet S is in a slightly softened state.

That is, a preferable nip position is as far upstream as possible (on the final roll 11 side) from the point D where the sheet S leaves the take-off roll 2, and particularly preferably, as shown in FIG. Then set it to contact takeoff roll 2.

The further upstream the touch roll 3 is, the less the free path of the sheet (distance without contact with the roll) becomes, the more uniform the state of peeling of the sheet S becomes, and the less the net-in of the sheet S becomes. Furthermore, since the sheet S is soft, it has a great effect of smoothing the surface. When the sheet S is made of polyvinyl chloride, the sheet S is
It is necessary to nip at a temperature of 120°C or higher, and the nip position can be set while observing the surface condition of the sheet S (degree of reduction in kneading unevenness).

The surface of the tatsuchi roll 3 is coated with an elastomer material, particularly silicone rubber, fluorine rubber, etc. with high heat resistance, in order to equalize the nip pressure, and the surface condition is finished as smooth as possible (preferably 3S or less). Tatsutilol's nip pressure is 0.1Kg/cm ~
A range of 6.0Kg/cm is good.

Average thickness of 250μm by the method of the present invention and the conventional method
When a hard vinyl chloride sheet was calender-molded, a sheet with the thickness distribution in the width direction as shown in FIG. A sheet with a significantly uniform thickness was obtained. Here, in the method of the present invention, Tatsuchiroll 3 has a hardness of 70
Using a silicone rubber-coated roll of 1.5°, the sheet S was placed at a position such that it could be wrapped around the touch roll 3 at an angle of about 90° and then nipped, as shown in FIG. Nip pressure is 1.0Kg/cm.

As explained above, according to the method of the present invention, the thickness run-out in the width direction of the sheet is significantly uniformized, the surface condition of the sheet is also improved, and the sheet has excellent post-processing properties such as printing and laminating. can get.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of an apparatus for implementing the method of the present invention. FIG. 2 is a diagram illustrating the state in which the sheet S is peeled off from the final roll 11, where A shows the conventional method and B shows the method of the present invention. FIG. 3 is a diagram showing the thickness distribution in the width direction of a sheet obtained by a conventional method. FIG. 4 is a diagram showing the thickness distribution in the width direction of a sheet obtained by the method of the present invention. 1... Calendar roll, 11... Final calendar roll (final roll), 2... Take-off roll, 3... Tatsuchi roll, S... Sheet.

Claims (1)

[Claims] 1. In a method of calendering a thermoplastic resin sheet, a tatsuchi roll 3 is provided on the final roll 11 side on the first take-off roll 2 that peels off the sheet from the final calender roll 11, and the sheet contacts the tatsuchi roll 3. A calender forming method characterized in that the sheet is nipped and taken off by a touch roll 3 on the take-off roll 2 while the sheet is still in a softened state.