JPH10151658A - Manufacture of thermoplastic resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a molten resin from necking at low cost and utilize the width of a T-die lip as large as possible so as to easily and stably produce a sheet by a method wherein weir plates projecting by specified length are provided at both end parts of the T-die lip. SOLUTION: Each weir plate 9 is installed at a position, at which the inner surface of the weir plate 9 is flush with the inner wall surface of a side wall. At the same time, the weir plate 9 projects beyond the surface of a T-die lip by 5-20mm, preferably 5-10mm. The width of the projecting part of the weir plate 9 is wider than the interval of the T-die lip and the more wider width makes no trouble. The projecting direction of the projecting part of the weir plate 9 may well be vertical or slightly tilt inwards or outwards. The tilt angle is set to be within 15 deg. inwards or outwards. As the material of the weir plate 9, aluminum, which easily peels off, is employed. Further, the thickness of the weir plate 9 is set to be within the range of 1-4mm from the view point of strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a thermoplastic resin sheet. More specifically, it is possible to prevent necking of a sheet-like molten resin extruded from a T-die lip,
The present invention relates to a method for producing a thermoplastic resin sheet capable of maximally utilizing the width of a die lip.

[0002]

2. Description of the Related Art Thermoplastic resin sheets (including films)
As a manufacturing method of the method, an air knife method, a polishing roll method and the like are known. In the air knife method, a sheet-like molten resin is extruded from a T-die lip, and is pressed against a cooling roll with air pressure to produce a sheet. It is hard to obtain. The polishing roll method is a method in which a sheet-like molten resin is sandwiched and pressed by a pair of metal rolls to simultaneously shape the thickness and surface properties of the sheet, and the molten resin sheet extruded from the T-die lip is drawn. Due to necking caused by the down, the extrusion width becomes considerably narrower than the T-die lip width, the sheet edge (the edge portion of the sheet) becomes thicker, and only a sheet having a width considerably smaller than the T-die lip width is obtained. For example, when a sheet having a thickness of 1.0 mm is manufactured by melt-extruding a polycarbonate resin from a T-die lip having a width of 1050 mm and an interval of 2.5 mm, only a sheet having a width of about 970 mm can be obtained, and a sheet having a width of 1000 mm can be reliably obtained. For this purpose, a T-die lip having a width of 1090 mm or more is required, so that the T-die needs to be changed, and the extruder must be stopped for a considerably long time. In addition, the product yield of the sheet with respect to the width of the T-die lip was 92 to 95%.

On the other hand, as a means for controlling the width of a sheet during production, there is known a method of installing a width control device on a T-die lip. For example, Japanese Patent Application Laid-Open No. Hei 8-187773 proposes a device that changes the opening width of an extruder die by appropriately adjusting an end block. In addition, the width of a sheet is reduced by preventing necking of a molten resin. As a method of maximizing the spread, a method of stretching a pinning wire in front of a cooling roll to discharge a high voltage and a method of blowing heated air to an ear portion of a molten resin sheet are known. However, all of these methods have a problem that the installation and maintenance of the equipment are expensive.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to prevent the necking of a molten resin at a low cost without requiring a new facility, and to easily and stably use a sheet by maximizing the width of a T-die lip. It is to provide a method that can be produced.

According to the present invention, as a result of intensive studies to achieve the above object, when extruding the molten resin from the T-die lip into a sheet shape, weir plates are provided at both ends of the T-die lip, and the wall surfaces of both ends are made T-shaped. We focused on preventing necking by protruding from the surface of the die lip, and as a result of further studies, completed the present invention.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a sheet having a thickness of 0.1 to 2 mm by melting a thermoplastic resin and extruding the sheet from a T-die lip. A method for producing a thermoplastic resin sheet, comprising providing a plate and projecting inner wall surfaces at both end portions from the surface of the T-die lip by 5 to 20 mm.

The present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of a sheet manufacturing apparatus suitable for carrying out the method of the present invention, in which 1 is a T die, 2 is a first cooling roll, 3 is a second cooling roll, 4 is The third cooling rolls 5 and 5 are a pair of take-off rolls, and the first to third cooling rolls all have mirror-finished surfaces, and a heat medium circulates inside thereof to control the temperature. ing. FIG. 2 is a sectional view of the T-die 1 in FIG.
Denotes a surface of the T-die lip, and 7 denotes side walls at both ends of the T-die lip. FIG. 3 is a cross-sectional view of the die 1 for explaining a state in which a weir plate is provided on the inner wall of the side wall 7 at both ends of the T-die lip in FIG. 2, where 8 is a pressing plate and 9 is a weir plate. . A part of the inner wall of the side wall 7 at both ends of the T-die lip in FIG.
Is provided. FIG. 4 shows a T-die 1 on which a weir plate 9 is installed.
It is a perspective view of.

The installation position of the weir plate 9 is such that the inner surface of the weir plate 9 forms the same surface as the inner wall surface of the side wall 7 before the inner wall is cut off, and is 5 to 2 from the surface 6 of the T-die lip.
0 mm, preferably 5 to 10 mm.
When the protruding length is less than 5 mm, the effect of preventing necking of the molten resin sheet is small. Conversely, when the protruding length is more than 20 mm, the cooling effect of the ear portions at both ends of the sheet increases, and cooling unevenness occurs on the entire surface of the sheet, and It is not appropriate because the appearance is impaired.

The width of the projecting portion of the weir plate 9 may be at least as long as the interval between the T-die lips, and may be widened. Also,
The projecting portion of the weir plate 9 may be vertically projected, but may be slightly bent inward or outward, and the angle of this bending is preferably within 15 degrees in and out. An arbitrary method is adopted for installing the weir plate 9. In addition to the above-described method, for example, the inner surface of the weir plate 9 is provided on the bottom surface of both ends of the T-die so that the inner surface of the weir plate 9 coincides with the inner surface of the side wall 7 of the lip. May be installed. In order to fix the weir plate to the T-die, it may be fixed with screws or the like. The material of the weir plate may be any material as long as the extruded sheet is easily peeled, and there is no particular limitation. For example, aluminum is used in order to prevent damage to the lip during installation, to process the weir plate, and to easily peel off the polycarbonate resin. Is preferred. The thickness of the weir plate is preferably in the range of 1 to 4 mm from the strength surface.

The thermoplastic resin used for the sheet in the present invention is not particularly limited as long as it is a thermoplastic resin that can be formed into a sheet by extrusion molding. Examples thereof include polyether sulfone, polysulfone, polycarbonate, polyesterimide, and polyester. , Polyamide, poly (meth)
Acrylic resins and the like can be mentioned. Among these resins, polycarbonate has a melting temperature of 280 ° C. from the viewpoint of thermal stability.
It is necessary to set before and after, and the melt viscosity at that time is high.
Therefore, when manufacturing a polycarbonate resin sheet of 2 mm or less without using a weir plate, necking of a molten sheet extruded from a die becomes particularly large. The method of the present invention is particularly preferable as a method of reducing this necking during the formation of a polycarbonate resin sheet.

The polycarbonate mentioned here is an aromatic polycarbonate obtained by reacting a dihydric phenol with a carbonate precursor. The dihydric phenol used here is mainly 2,2-bis (4-hydroxyphenyl) propane (commonly known as bisphenol A), but a part or all of the dihydric phenol may be replaced by another dihydric phenol. . Other dihydric phenols include, for example, 1,1
-Bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2
-Bis (4-hydroxy-3,5-dimethylphenyl)
Propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, bis (4-hydroxyphenyl)
Sulfide, bis (4-hydroxyphenyl) sulfonic acid and the like. Examples of the carbonate precursor include carbonyl halide, carbonyl ester, and haloformate. Specific examples include phosgene, diphenyl carbonate, and dihaloformate of dihydric phenol. Phosgene and diphenyl carbonate are particularly preferred. In order to produce a polycarbonate from a dihydric phenol and a carbonate precursor, any method is adopted, but an interfacial polymerization method of dihydric phenol and phosgene,
A transesterification method between dihydric phenol and diphenyl carbonate is preferred. In producing polycarbonate, a molecular weight modifier, a branching agent, a catalyst and the like can be used as required.

The sheet extruded by the method of the present invention is cooled by an arbitrary method, for example, a plurality of cooling rolls, and then, if necessary, is taken up by a roller table or the like. Is laminated and cut into a predetermined size or wound up to form a sheet.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be further described below with reference to examples. The evaluation was based on the following method. (1) Sheet thickness: The thickness 30 mm inside from the ear was measured with a micrometer. (2) Sheet extrusion width: The width of the sheet including the ear portion melt-extruded from the T-die lip and cooled and solidified by the cooling roll is m.
Indicated by m. (3) Δ width: A value obtained by subtracting the extrusion width of the sheet from the width of the T die lip. The smaller the Δ width, the wider the product width can be obtained, which is industrially advantageous. (4) Appearance of sheet: Observed visually, and indicated by ○ when the surface was uniform, and △ when uneven. (5) Sheet yield: The ratio of the width of the production sheet (without cutting the ears) to the width of the T-die lip was expressed in%.

Examples 1 to 3 Polycarbonate sheets were produced using an extruder equipped with the apparatus shown in FIG. The width of the T-die lip is 1050, 1203, 15 shown in Table 1.
Each T-die having a thickness of 00 mm was installed, and a weir plate of an aluminum plate having a thickness of 2.5 mm was embedded in each end of the T-die lip, and the length shown in Table 1 was protruded. Was adjusted to 150 mm, and a mirror-finished cooling roll having a diameter of 300 mm was used. Viscosity average molecular weight 25,20 prepared from bisphenol A and phosgene
0 polycarbonate powder at a cylinder temperature of 280 ° C.
The sheet was extruded into a sheet at a T-die lip temperature of 280 ° C. and a discharge rate of 250 kg / hour, sandwiched by a pair of mirror-surface cooling rolls, and taken up by a take-off roll to obtain a sheet having the thickness shown in Table 1. The temperatures of the first cooling roll 2, the second cooling roll 3, and the third cooling roll 4 having mirror surfaces were set to 120 ° C, 130 ° C, and 115 ° C, respectively. Table 1 shows the evaluation results.

Comparative Examples 1 to 3
Not embedded at both ends of die lip (projection length 0m
Except for m), a polycarbonate sheet was produced in the same manner as in Examples 1 to 3, and the evaluation results are shown in Table 1.

Comparative Example 4 A polycarbonate resin sheet was manufactured in the same manner as in Example 2 except that the protrusion length was set to 30 mm. The evaluation results are shown in Table 1.

[0017]

[Table 1]

[0018]

According to the method of the present invention, the product width of the sheet can be made close to the width of the T-die lip at a low cost without introducing new equipment, and a sheet having a wider product width can be obtained. This is extremely effective as a measure to increase the product yield by 3 to 5%.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a sheet manufacturing apparatus suitable for carrying out the method of the present invention.

FIG. 2 is a sectional view of a T-die in FIG. 1;

FIG. 3 is a cross-sectional view of a die for explaining a state in which weir plates are provided on inner walls of side walls 7 at both ends of a T-die lip in FIG. 2;

FIG. 4 is a perspective view of a T-die on which a weir plate is installed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 T die 2 1st cooling roll 3 2nd cooling roll 4 3rd cooling roll 5 Take-up roll 6 Surface of T die lip 7 Side wall of both ends of T die 8 Holding plate 9 Weir plate

Claims (2)

[Claims] 1. When a thermoplastic resin is melted and extruded into a sheet from a T-die lip to produce a sheet having a thickness of 0.1 to 2 mm, weir plates are provided at both ends of the T-die lip. The inner wall surface is 5-20mm from the surface of T-die lip
A method for producing a thermoplastic resin sheet, comprising: 2. The method for producing a thermoplastic resin sheet according to claim 1, wherein the thermoplastic resin is a polycarbonate resin.