Method and apparatus for producing thermoplastic polymer film

Abstract

To provide a novel method and apparatus for producing a thermoplastic resin polymer film which can eliminate or reduce an anisotropy of the produced thermoplastic polymer film.SOLUTION: While a molten thermoplastic polymer is extruded from an annular die 2 into a cylindrical shape to mold a cylindrical body 10, a diameter expansion jig 3 arranged on a discharge port side of the annular die 2 is brought into contact with an inside of the cylindrical body 10 extruded from the annular die 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for producing a thermoplastic polymer film. [Background technology]

[0002] Conventionally, a technique for forming a film by an inflation method has been known. For example, Patent Document 1 discloses a method and an apparatus for forming a film while suppressing bubble expansion in the inflation method. It is also known that when a film is molded, there is anisotropy, in which the orientation of molecular chains differs between the extrusion direction (MD) and the direction perpendicular to it (TD). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 150307 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have conducted extensive research in order to provide a novel thermoplastic resin polymer film manufacturing method and manufacturing apparatus that can eliminate or reduce the anisotropy of the produced thermoplastic polymer film, and as a result have completed the present invention. [Means for solving the problem]

[0005] The method for producing a thermoplastic polymer film according to the present invention is a method in which a molten thermoplastic polymer is extruded into a cylindrical shape from an annular die to form a cylindrical body, and a diameter expansion tool arranged on the discharge outlet side of the annular die is brought into contact with the inside of the cylindrical body, thereby expanding the diameter of the cylindrical body and stretching it in the circumferential direction.

[0006] In addition, the thermoplastic polymer film manufacturing apparatus of the present invention includes an annular die that extrudes molten thermoplastic polymer into a cylindrical shape, and an expansion tool arranged on the outlet side of the annular die, and is configured to expand the cylindrical body made of the thermoplastic polymer extruded from the annular die and stretch it in the circumferential direction by bringing the expansion tool into contact with the inside of the cylindrical body made of the thermoplastic polymer extruded from the annular die. Effect of the Invention

[0007] According to the present invention, the anisotropy of the produced thermoplastic polymer film can be eliminated or reduced. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is an explanatory diagram showing an example of a method for producing a thermoplastic polymer film according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram showing another example of the method for producing a thermoplastic polymer film according to an embodiment of the present invention. [Diagram 3] 1 is a pole diagram obtained by a pole measurement method for evaluating the anisotropy of the film obtained in Example 1. [Figure 4] 1 is a pole figure obtained by a pole measurement method for evaluating the anisotropy of the film obtained in Example 2. [Diagram 5] 1 is a pole figure obtained by a pole measurement method for evaluating the anisotropy of the film obtained in Example 3. [Figure 6] 1 is a pole figure obtained by a pole measurement method for evaluating the anisotropy of the film obtained in Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0010] First, an overview of the thermoplastic polymer film manufacturing apparatus according to this embodiment will be described. FIG. 1 shows an example of the apparatus.

[0011] In this embodiment, the apparatus 1 is configured to include an annular die 2 that extrudes molten thermoplastic polymer into a cylindrical shape, and an expansion tool 3 arranged on the outlet side of the annular die 2, but in the illustrated example, these are shown diagrammatically.

[0012] The annular die 2 can be configured to be attached to an extruder (not shown), and the thermoplastic polymer melt-kneaded and fed by the extruder is extruded into a cylindrical shape through a slit 2a formed in a ring shape. In the illustrated example, a disk-shaped diameter expansion jig 3 made of a metal material such as stainless steel is supported by a support 3a vertically erected on a core located on the inner periphery side of the slit 2a and disposed on the discharge port side of the annular die 2, but the configuration of the diameter expansion jig 3 is not limited thereto. For example, the diameter expansion jig 3 may be formed in a ring shape and supported by the support 3a via a spoke-shaped member.

[0013] More specifically, the diameter expanding jig 3 includes an outer peripheral edge portion that is continuous in the circumferential direction, and the outer peripheral edge portion is disposed concentrically with the discharge port of the annular die 2, i.e., the opening of the slit 2a, and the surface including the outer peripheral edge portion can be disposed so as to be perpendicular to the direction in which the thermoplastic polymer is extruded. In this case, the outer diameter of the diameter expanding member 3 is preferably 2 to 5 times the diameter of the discharge port of the annular die 2, and the width of the discharge port (width of the slit 2a) is preferably 0.50 to 2.00 mm.

[0014] Next, a method for producing a thermoplastic polymer film according to this embodiment will be described, along with a configuration of an apparatus 1 for suitably carrying out the method.

[0015] In this embodiment, molten thermoplastic polymer is extruded into a cylindrical shape from an annular die 2 to form a cylindrical body 10, and is pulled up along the extrusion direction by a winding device (not shown), while bringing the inside of the cylindrical body 10 extruded from the annular die 2 into contact with an expansion jig 3 arranged on the discharge outlet side of the annular die 2.

[0016] As a result, the cylindrical body 10 is expanded in diameter and stretched in the circumferential direction, and at this time, as shown in Fig. 1, it is preferable that the cylindrical body 10 extruded from the annular die 2 reaches the diameter expansion jig 3 while expanding in diameter, and the diameter expansion jig 3 comes into contact with the cylindrical body 10 at the expanded diameter end portion of the cylindrical body 10, so that the cylindrical body 10 extruded continuously from the annular die 2 is expanded in diameter. Although not particularly shown, an auxiliary jig formed with a smaller diameter than the diameter expansion jig 3 may be disposed between the annular die 2 and the diameter expansion jig 3 to assist the cylindrical body 10 extruded from the annular die 2 in expanding in diameter.

[0017] In the illustrated example, the cylindrical body 10 expanded in diameter in this manner is pulled up along the extrusion direction and guided by a guide plate 4 located above the annular die 2, where it is gradually crushed to become flat. After being folded into a flat shape by the nip rolls 5, both ends are cut by a slitter or the like and wound up as two flat films, or the film is wound up as it is as a bag-shaped film. Although not particularly illustrated, in addition to the guide plate 4, an auxiliary jig for supporting the outer surface of the cylindrical body 10 may be provided to stabilize the cylindrical body 10 and assist in folding it around the nip rolls 5.

[0018] According to this embodiment, when extruded from the annular die 2, the molecular chains of the thermoplastic polymer tend to be oriented in the extrusion direction (MD direction); however, by expanding the diameter of the cylindrical body 10 using the diameter expansion tool 3 and stretching and orienting it in the circumferential direction (TD direction), the anisotropy of the thermoplastic polymer film produced can be eliminated or reduced.

[0019] When expanding the diameter of the tubular body 10 extruded from the annular die 2, it is preferable that the diameter expansion jig 3 is configured to include an outer peripheral edge portion that is continuous in the circumferential direction, as described above. It is preferable that the outer peripheral edge portion of the diameter expansion jig 3 is brought into contact with the inside of the tubular body 10 without interruption over the entire circumference along the circumferential direction of the tubular body 10 to expand the diameter of the tubular body 10. In this way, it is possible to stretch the tubular body 10 more uniformly along the circumferential direction while suppressing inconveniences such as the occurrence of wrinkles when expanding the diameter of the tubular body 10.

[0020] In addition, it is preferable to increase the slipperiness of the outer peripheral edge of the diameter expansion jig 3 with respect to the tubular body 10 extruded from the annular die 2 by rounding the cross section into an arc shape to reduce the contact area or by performing a surface treatment such as blasting, hard chrome plating, or hard chrome carbide plating. Increasing the slipperiness of the outer peripheral edge of the diameter expansion jig 3 can suppress the stretch orientation of the tubular body 10 in the extrusion direction, which is advantageous in eliminating or reducing the anisotropy of the produced thermoplastic polymer film and improving the isotropy. In addition, it is preferable that the diameter expansion jig 3 and the support 3a are located at the center of the annular die 2, but an adjustment mechanism for moving the support 3a from the center of the annular die 2 may be provided in order to adjust the thickness of the cylindrical body 10.

[0021] Furthermore, when the tubular body 10 extruded from the annular die 2 comes into contact with the expansion jig 3, if it wraps around to the underside of the expansion jig 3 and partially comes into contact with the underside of the expansion jig 3, this will undesirably cause the tension acting on the tubular body 10 to fluctuate or the behavior of the tubular body 10 to become unstable as it is pulled up, thereby causing wrinkles or uneven thickness in the tubular body 10.

[0022] In order to effectively avoid such a problem, the diameter expansion jig 3 is preferably formed so that the peripheral edge portion including the outer peripheral edge portion is inclined toward the opposite side to the extrusion direction of the cylindrical body 10, as shown in Fig. 2. In this way, it is possible to prevent the cylindrical body 10 extruded from the annular die 2 from wrapping around to the lower surface side of the diameter expansion jig 3 so that the cylindrical body 10 is expanded in diameter by contacting only the outer peripheral edge portion of the diameter expansion jig 3. When the diameter expansion jig 3 is formed in this manner, the inclination angle θ of the peripheral edge portion of the cylindrical body 103 is preferably 20 to 80°.

[0023] When applying this embodiment to produce a thermoplastic polymer film, various thermoplastic polymers that can be formed into films can be used as the thermoplastic polymer, including olefin-based resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; polyvinyl alcohol-based resins such as polyvinyl alcohol and ethylene-vinyl alcohol; polyamide-based resins such as nylon; and polyester-based resins such as polyethylene terephthalate, liquid crystal polyester, and liquid crystal polyester amide.

[0024] Among these, thermoplastic liquid crystal polymers that exhibit optical anisotropy in a molten state, such as liquid crystal polyesters and liquid crystal polyester amides, have the characteristic that they have high fluidity in a molten state, but have a fast cooling and solidifying speed. Therefore, when attempting to form a film by a commonly known inflation method, it is accompanied by difficulties such as the need for complicated temperature control, but according to the present embodiment, a liquid crystal polymer film in which anisotropy is eliminated or reduced can be suitably manufactured using a thermoplastic liquid crystal polymer.

[0025] To explain this in more detail, in this embodiment, the position of the diameter expansion jig 3 relative to the discharge port of the annular die 2, more specifically, the position where the diameter expansion jig 3 contacts the inside of the cylindrical body 10 extruded from the annular die 2, is appropriately adjusted, so that the cylindrical body 10 extruded from the annular die 2 can be expanded in diameter and stretched and oriented in the circumferential direction before the cooling and solidification of the plastic liquid crystal polymer progresses. Furthermore, the cylindrical body 10 is steadily expanded in diameter at a diameter expansion ratio determined by the ratio between the diameter of the discharge port of the annular die 2 and the outer diameter of the diameter expansion member 3, which makes it possible to easily control the circumferential stretch orientation and to stably pull up the expanded cylindrical body 10. At that time, since the shape of the cylindrical body 10 can be maintained without supplying air as in the inflation method, it is also possible to produce a film by cutting the cylindrical body 10 while pulling it up so that its circumferential length becomes the film width, although this is not particularly shown.

[0026] In this manner, in order to suitably produce a liquid crystal polymer film in which anisotropy has been eliminated or reduced, it is preferable to arrange the diameter expansion jig 3 so that it contacts the inside of the tubular body 10 extruded from the annular die 2 at a position where its height from the discharge outlet of the annular die 2 (the distance along the extrusion direction) is 40 to 60 mm. In addition, the stretch orientation in the extrusion direction of the tubular body 10 can be controlled by appropriately adjusting the discharge amount when the tubular body 10 is extruded from the annular die 2 and the take-up speed when the tubular body 10 is pulled up. The discharge amount is preferably 30 to 1000 g / min, and the take-up speed is preferably 0.5 to 5 m / min. Furthermore, since the thermoplastic liquid crystal polymer has a property that the melt viscosity decreases when oriented in the flow direction, the width of the discharge opening of the annular die 2 (the width of the slit 2a) is preferably set to 0.50 to 0.90 mm. EXAMPLES

[0027] The present invention will now be described in more detail with reference to specific examples.

[0028] [Example 1] A circular die with an outlet diameter of 43 mm and an outlet width of 0.5 mm was fitted with a disk-shaped expansion tool with a diameter of 159 mm so that the height from the outlet was 45 mm, and the circular die was attached to an extruder (Labo Plastomill, manufactured by Toyo Seiki Co., Ltd.). As the thermoplastic polymer, liquid crystal polyester (A950RX, manufactured by Polyplastics Co., Ltd.) was prepared and thoroughly dried by hot air drying (150° C., 6 hours).

[0029] The extruder temperature was set to 300°C, and the temperature of the discharge part of the annular die was set to 270°C. The liquid crystal polyester melt-kneaded by the extruder was extruded into a cylindrical shape from the annular die at a discharge rate of 82 g / min to form a cylindrical body, which was then pulled up along the extrusion direction. A diameter-expanding jig was brought into contact with the inside of the cylindrical body continuously extruded from the annular die to expand and stretch it, and the body was taken up at a take-up speed of 2 m / min to obtain a film with a thickness of 62 μm.

[0030] At that time, the tubular body extruded from the annular die contacted only the outer peripheral edge portion of the expansion jig and, as it slid along the outer peripheral edge portion of the expansion jig, expanded in diameter to the same diameter as the expansion jig, and after passing through the expansion jig, the expanded diameter remained constant and the tubular body was pulled up stably in the extrusion direction. Furthermore, even if a hole was formed in the cylindrical body, the diameter of the cylindrical body did not change, and molding could be continued.

[0031] [Evaluation of anisotropy] The anisotropy of the obtained film was evaluated using an X-ray diffraction device (Rigaku Corporation: SmartLab). The evaluation was performed using the reflection pole measurement method with an incident angle of 2θ = 20°. The obtained pole figure is shown in Figure 3, and it was confirmed that the pole figure drew concentric circles, and the anisotropy was extremely well resolved.

[0032] [Example 2] A film having a thickness of 20 μm was obtained in the same manner as in Example 1, except that the diameter of the diameter expansion jig was 120 mm, the temperature of the discharge part of the annular die was 280° C., and the discharge rate was 34 g / min. The anisotropy of the film was evaluated in the same manner as in Example 1. The obtained pole figure is shown in FIG. 4, and it was confirmed that the pole figure drew an ellipse and the anisotropy was reduced.

[0033] [Example 3] A film having a thickness of 19 μm was obtained in the same manner as in Example 1, except that the discharge rate was set to 62 g / min. The anisotropy of the film was evaluated in the same manner as in Example 1. The obtained pole figure is shown in Figure 5, and it was confirmed that the pole figure drew an ellipse and the anisotropy was reduced.

[0034] [Comparative Example 1] An annular die with a discharge port diameter of 43 mm and a discharge port width of 0.5 mm was attached to an extruder (Labo Plastomill, manufactured by Toyo Seiki Seisakusho), and the temperature of the extruder was set to 300° C., and the temperature of the discharge part of the annular die was set to 290° C. The same liquid crystal polyester as in Example 1 was extruded into a cylindrical shape from the annular die at a discharge rate of 34 g / min, and while performing a winding operation at a take-up speed of 2 m / min, air was supplied so that the diameter expansion ratio was 1.5 times without using a diameter expansion tool, and film molding was performed by the inflation method.

[0035] In this case, since the liquid crystal polyester is cooled and solidified so quickly that it is difficult to stretch it, it is extremely difficult to keep the bubble diameter constant. Furthermore, if a hole occurs in the bubble, the internal pressure of the bubble decreases and the bubble collapses, making stable molding impossible.

[0036] A portion having a predetermined diameter expansion ratio was cut out from the obtained film, and the anisotropy of the film was evaluated in the same manner as in Example 1. The obtained pole figure is shown in Figure 6, and it was confirmed that the pole figure drew a horizontal line and had high anisotropy.

[0037] Although the present invention has been described above by showing preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.

[0038] For example, in the above-described embodiment, the cylindrical body extruded from the annular die 2 is brought into contact with the expansion jig 3 to be expanded in diameter without supplying air as in the inflation method, but if necessary, air may be supplied into the inside of the expanded cylindrical body as an auxiliary means to maintain the shape of the expanded cylindrical body. [Explanation of symbols]

[0039] 1 device 2 Circular Die 2a Slit (outlet) 3 Expansion tool 10 Cylindrical body

Claims

1. A method for producing a thermoplastic polymer film, characterized in that a molten thermoplastic polymer is extruded into a cylindrical shape from an annular die to form a cylindrical body, and a diameter expansion tool arranged on the discharge outlet side of the annular die is brought into contact with the inside of the cylindrical body, thereby expanding the diameter of the cylindrical body and stretching it in the circumferential direction.

2. 2. A method for producing a thermoplastic polymer film as described in claim 1, wherein the tubular body extruded from the annular die reaches the expansion jig while expanding in diameter, and the expansion jig contacts the tubular body at the expansion end portion of the tubular body, thereby expanding the diameter of the tubular body continuously extruded from the annular die.

3. The method for producing a thermoplastic polymer film according to claim 1 , wherein the diameter expanding member includes an outer peripheral edge portion that is continuous in the circumferential direction, and the outer peripheral edge portion is in contact with the cylindrical body over the entire circumferential direction.

4. The method for producing a thermoplastic polymer film according to claim 3 , wherein the peripheral edge of the diameter expanding member, including the outer peripheral edge, is inclined toward the opposite side to the extrusion direction of the tubular body.

5. The method for producing a thermoplastic polymer film according to any one of claims 1 to 4, wherein the outer diameter of the diameter expanding member is set to 2 to 5 times the diameter of the discharge opening of the annular die.

6. The method for producing a thermoplastic polymer film according to any one of claims 1 to 4, wherein the thermoplastic polymer is a thermoplastic liquid crystal polymer that exhibits optical anisotropy in a molten state.

7. an annular die for extruding a molten thermoplastic polymer into a cylindrical shape; a diameter expansion tool disposed on the discharge port side of the annular die; Including, A thermoplastic polymer film manufacturing apparatus, characterized in that the expansion tool is brought into contact with the inside of a cylindrical body made of the thermoplastic polymer extruded from the annular die, thereby expanding the cylindrical body and stretching it in the circumferential direction.

8. The apparatus for producing a thermoplastic polymer film according to claim 7 , wherein the diameter expanding member includes a peripheral edge portion that is continuous in the circumferential direction.

9. The apparatus for producing a thermoplastic polymer film according to claim 8 , wherein the peripheral edge of the diameter expanding member, including the outer peripheral edge, is inclined in a direction opposite to the extrusion direction of the tubular body.

10. 10. The apparatus for producing a thermoplastic polymer film according to claim 7, wherein the outer diameter of the diameter expanding member is 2 to 5 times the diameter of the discharge opening of the annular die.

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