JPS63252717A - Glazing device for thermoplastic resin sheet and so on - Google Patents

Abstract

PURPOSE:To improve a closely contacting property of resin to a cooling roll by attracting action of static electricity by providing a static electricity generator and the thin wire for charging to give static electricity to sheetlike molten resin. CONSTITUTION:Bearing parts 6a, 6b are provided at both ends of the first cooling roll 4. Plastic terminal boxes 8a, 8b with insulating property are attached to the platelike brackets 7a, 7b fitted to the tops of both bearings 6a, 6b. The terminal boxes 8a, 8b are connected to the static electricity generator 9 generating static electricity by D. C. high voltage source arranged outside. The thin wire 10 for charging is arranged in between the terminal boxes 8a and 8b from the side B of the terminal box 8a in parallel with the first cooling roll 4, and static electricity is given to the sheetlike molten resin extruded from the die 2. The both end sides of the thin wire 10 for charging except the width of the molten resin, are covered with insulating plastic tubes 11a, 11b, whereby the discharging between the thin wire 10 for charging and the cooling roll 4 is prevented.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to extrusion molding of thermoplastic resin sheets, etc.
In particular, it relates to a glazing device that cools and solidifies a sheet or film of molten resin extruded from a die, and at the same time improves gloss and transparency.

(Prior art) Conventional glazing equipment is used to cool and solidify a molten resin sheet or film (hereinafter referred to as a sheet) extruded from a die and at the same time improve gloss and transparency, as shown in Figure 8. A set of three rolls 21, 22, and 23 are arranged in parallel, for example, in a vertical direction, and are rotated by a drive device (not shown), and the upper roll 21 and lower roll 23 are moved and pressed by bearings at both ends thereof by a cylinder device (not shown). However, it is configured so that it can be crimped onto a fixed central roll 22.

Further, each roll is configured to circulate water, oil, or the like whose temperature is controlled by a heating/cooling device 24 to maintain a uniform temperature over the entire length of the roll.

In Fig. 8, 25 is the die, 26 is the roll 21, 22゜23
The molten resin extruded from the die 25 by the side frames that make up the bearings at both ends forms a resin pool C (hereinafter referred to as bank) 27 almost uniformly throughout the entire roll between the middle roll 22 and the lower roll 23. The sheet surface is smoothed while being rolled between rolls, and the sheet is cooled by being brought into close contact with the roll surface, and after passing around the middle roll 22 for about half a turn, it is rolled around the upper roll 21 for about half a turn. The surface is transferred and cooled and solidified to complete the polishing, and then taken off by a taking off device (not shown) provided in front of the die 25 (to the left in the figure).

(Problems to be Solved by the Invention) As mentioned above, in the roll polishing apparatus described above, when forming a sheet with a sheet thickness of 2 mm or less and a thickness of about 1 bleach, pressing of the middle roll and lower roll is required. A force of 30Kq/σ or more is required,
9 to 150 to 200 for sheet thickness 0.4 inch molding
There are some resins that require a pressing force of /crn, and large deflections occur with ordinary rolls, requiring the use of expensive drill trawls and deflection correction devices, which is uneconomical and prevents the formation of formed sheets. Also, due to the high pressing force, the resin material molecules were oriented, resulting in a difference in thermal shrinkage rate of 6 to 7 in the flow direction and 3 in the middle direction. In addition, in bank forming, as the sheet thickness becomes thinner, the amount of bank must be reduced and maintained stably, but currently it is difficult to maintain stability, and as a result, bank marks,
Defects such as sink marks were likely to appear on the sheet surface, resulting in poor product yield.

Therefore, the present invention is a completely new method that replaces bank molding, which has the disadvantage of "=", by continuously supplying sheet-shaped molten resin from a die, and controlling the resin thickness by changing the amount of supply or increasing or decreasing the take-up speed. At the same time, static electricity is applied to the molten resin, and the entire charging force is utilized to bring the sheet into close contact with the surface of the cooling roll, sealing the entire surface of the roll!・The purpose is to provide a complete device that can perform transfer and polishing.

[Structure of the invention]

(Another means to solve the problem) In order to achieve the above object, the present invention continuously supplies molten resin in the form of a sheet through a die or between a plurality of cooling rolls arranged in parallel. The glazing of the sheet forming equipment for glazing thermoplastic resin sheets and films is characterized in that the glazing equipment is equipped with a static electricity generator and a charged thin wire for imparting static electricity to the molten resin sheet. (Function) In a device configured in this way, the resin to which static electricity has been forcibly applied passes between the cooling rolls, When it is wound and flows, the adhesion to the cooling roll is further improved due to the attraction effect of static electricity, which further improves transferability.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

In FIG. 1, reference numeral 1 denotes an adapter through which molten resin from an extruder (not shown) passes in the direction of arrow A. 2 is a die for extruding the molten resin in the form of a sheet, and the molten resin 3 in the sheet form extruded from the die 2 is taken up in close contact with the first cooling roll 4. 2 cooling rolls 5.

Bearings 6a and 6b are provided at both ends of the first cooling roll 40, and terminal boxes 8a and 8be made of insulating plastic are attached to plate-shaped brackets 7a and 7b attached to the tops of both bearings 6a and 5b. the terminal box 3a;
3b is connected to a static electricity generator 9 that generates static electricity using a high DC electric field installed outside. Between the side surface B of the terminal box 8a and the terminal box 8b,
A thin charging wire 10 is connected in parallel to the first cooling roll 4 to apply static electricity to the sheet-shaped molten resin extruded from the die 2. The thin charging wire 10
Both end sides other than those in the molten resin are covered with insulating plastic tubes lla and llb, and the thin charging wire 1
0 and the cooling roll 4 is prevented from occurring.

In addition, the thin charging wire 10 applies static electricity to the molten resin 3 most effectively and is used for position adjustment in order to bring it into close contact with the first cooling roll 4) +28. +2b and 138. +3b is provided.

The first cooling roll 4 is connected from the shaft end (left side in the figure) to a heating and cooling device 15 via a rotary joint 14', and temperature-controlled water or oil is circulated inside the first cooling roll 4 to cool the entire roll. It maintains a uniform temperature over its length.

FIGS. 2 to 5 schematically show the apparatus of the embodiment, and in particular, the arrangement of the charged fine wires and the rotational direction of the cooling roll as explained in the previous embodiment are completely changed.

In the description, the same numbers will be given to the constituent members that are the same as those in FIG. 1 described above.

In FIGS. 2 and 3, a charged thin wire 10 is placed close to the molten resin 3 extruded from the die 2 while it is in contact with the first cooling roll 4; When the molten resin 3 adheres to and solidifies the surface of the first cooling roll 40 over a long distance, the first cooling roll 4
The surfaces that are more affected by this, that is, the 7 surfaces, have gloss more effectively.

In FIG. 3, the charged thin wire 10 was used to charge the sheet, but the effect was small, and the difference in gloss appearing on both sides of the formed sheet was small.

In FIGS. 4 and 5, the charged thin wires 10 are placed at two locations: near where the molten resin 3 extruded from the die 2 contacts the first cooling roll 4, and near where the sheet contacts the second cooling roll 5. The effect of the glazing is greater than that shown in Figs. 2 and 3, but in Fig. 4, the first cooling roll 4 and the third
Since the adhesion of the cooling roll 16 is exhibited, the entrance surface of the molded sheet 1 has a superior gloss.

In FIG. 5, since both sides of the charged thin wire IO are affected to the same extent, both sides of the formed sheet appear to have the same level of gloss.

Next, to describe the effects of the embodiment, in Fig. 1, the thin charging wire 10'a = attached box 8a + 8bf
As shown by the arrows in the figure, there are bolts 12a on the top, bottom, left and right.

Since it is adjustable by +2b and 138.13b, the charged thin wire can be adjusted to the position where the charged thin wire produces the most effect of imparting static electricity.

Figure 6 shows the test results conducted using this device.

In this test, all dies with a width of 650 ffa were used.

In the molding conditions of test Nh2, the static electricity applied heat is a state in which no pressing force is applied to the cooling roll, no bank is formed between the rolls, and so-called bank molding is not performed.

The position of the charged thin wire refers to the X dimension shown in FIG.

As can be seen from Fig. 6, film formation was impossible without bank forming and without applying static electricity, but by applying static electricity, the sheet take-up speed was
Over a high range from 2.2 my'm to l 1.5m//+#, and in sheet thickness from 0.48 mm to 1
．． Good polishing could be achieved in all six cases.

The heat shrinkage rate of the molded sheet was 3 in both the machine direction and the width direction.

〔Effect of the invention〕

According to the present invention, it is possible to apply static electricity to the molten resin, make full use of the charging force to bring the sheet lather into close contact with the surface of the cooling roll, and transfer the roll surface to create a gloss. Therefore, there is no need for the device to have the strength to apply the pressing force, and a cooling roll deflection correction device is often required.

Since orientation does not occur in the molded sheet or film, 1) there is no difference in heat shrinkage rate in the direction or flow direction, and the amount of molten resin extruded from the die and the sheet take-up device are precisely controlled. Since it is easy to use, defects on the sheet surface have been eliminated.

Moreover, it is also possible to change the sheet thickness continuously and in a short time without stopping the apparatus, simply by changing the extruder rotational speed and take-up speed.

[Brief explanation of drawings]

FIG. 1 is a specific configuration diagram of an apparatus showing an embodiment of the present invention, FIGS. 2 to 5 are schematic diagrams of embodiments of the present invention,
FIG. 6 is a table showing test results according to the present invention, FIG. 7 is a diagram showing the positions of charged thin lines in the table of FIG. 6, and FIG. 8 is a schematic diagram of a conventional device. 2...Die, 4...First cooling roll, 5...Second cooling roll, 9...Static electricity generator, 10...Thin wire for charging, 15...Heating and cooling device.

Claims (3)

[Claims] (1) A glazing device of a sheet forming machine that glazes thermoplastic resin sheets and films by continuously supplying sheet-shaped molten resin from a die between cooling rolls arranged in parallel. A glossing device for a thermoplastic resin sheet, etc., characterized in that it is equipped with a static electricity generator and a charged fine wire for imparting static electricity to a sheet of molten resin. (2) The thermoplastic resin sheet according to claim 1, wherein the static electricity generator and the charged thin wire are provided close to each other so that the sheet contacts the first cooling roll counting from the die. etc. glazing equipment. (3) The heat generating device according to claim 1, characterized in that the static electricity generating device and the charged thin wire are provided close to each other so that the sheet is in contact with the first and second cooling rolls counted from the die. Glazing device for plastic resin sheets, etc.