JPH1177801A - Manufacture of thermoplastic resin film and equipment therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of a fault in external appearance due to catching-in of air or the like and thereby to obtain a film of high transparency and high gloss. SOLUTION: In this manufacturing method, thermoplastic resin 11A in a molten state is cooled in surface pressure welding between a cooling roll 16 and a seamless metallic endless belt 15 and formed into a thermoplastic resin film 11. When the thickness of the thermoplastic resin film 11 is denoted by St and that of the metallic belt 15 by Bt, in this case, the thicknesses are set at Bt<=10×St and 0.2 mm<=Bt<=1.5 mm. As for the thermoplastic resin, polypropylene is used, for instance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for producing a thermoplastic resin film.

[0002]

BACKGROUND OF THE INVENTION A chill roll method in which a cooling roll (chill roll) is used and a molten thermoplastic resin is brought into contact with the cooling roll to form a thermoplastic resin sheet or film. There is. In such a chill roll method, when a relatively thick sheet is manufactured, a high gloss sheet can be obtained because a mirror roll is used. However, in the case of a film having a relatively small thickness, cooling unevenness occurs at a high speed, so that it is difficult to produce the film at a high speed.

For this reason, when manufacturing a film,
Forming is performed at high speed using a roll having a large surface roughness, for example, a satin roll. However, in this case, since air is entrapped between the molten resin and the roll, the film obtained by this chill roll method has poor transparency.

On the other hand, in recent years, a sheet manufacturing method has been proposed in which a thermoplastic resin in a molten state is cooled and formed into a thermoplastic resin sheet while being pressed in a planar manner while being sandwiched between a roll and a metal endless belt. Have been. Such a belt process has made it possible to significantly improve the quality and productivity of the film, but has not sufficiently solved the problem of poor appearance due to air entrapment or the like.

Accordingly, the present invention provides a method and apparatus for producing a thermoplastic resin film capable of obtaining a highly transparent and high gloss film while preventing appearance defects due to air entrapment or the like. With the goal.

[0006]

According to a first aspect of the present invention, a thermoplastic resin in a molten state is cooled while being pressed in a planar manner between a cooling roll and a metal belt to form a thermoplastic resin film. A method for producing a thermoplastic resin film, wherein the thickness of the thermoplastic resin film is
t, when the thickness of the metal belt is Bt, Bt ≦ 10
× St, and 0.2 mm ≦ Bt ≦ 1.5 mm.

If Bt is greater than 10 × St,
The appearance defect cannot be prevented. If Bt is smaller than 0.2 mm, the durability of the belt deteriorates. Also, Bt is 1.5m
If it is larger than m, the cooling efficiency of the resin film is deteriorated, and the rigidity of the belt becomes excessive, so that the appearance defect such as a bank mark becomes severe. The resin type of the thermoplastic resin is arbitrary, for example, polyethylene, polypropylene,
Polystyrene, nylon-6, nylon-66 and the like can be mentioned. In this resin, sorbitol type,
A nucleating agent such as aluminum benzoate or sodium may be contained.

Preferably, the cooling roll has a suitable cooling means incorporated therein. Further, from the viewpoint of cooling efficiency, it is preferable that the metal belt is also cooled in advance by contacting it with a cooling roll or the like. The moving speed of the metal belt may be any speed, but is preferably 20 m / min or more from the viewpoint of productivity. The film may be relatively thick and may be called a sheet.

According to the present invention, air entrapment can be prevented, so that appearance defects do not occur. In addition, since the cooling capacity of the thermoplastic resin film can be sufficiently secured, the processing speed can be increased, and as a result, the production efficiency can be increased. Further, the elasticity of the metal belt can reduce the occurrence of bank, resin orientation, and the like. Furthermore, since the durability of the metal belt is improved,
It can be used for a long time.

[0010] A method for producing a thermoplastic resin film according to a second invention of the present invention is characterized in that, in the first invention, the thermoplastic resin is polypropylene. As the polypropylene, a homopolymer of polypropylene, a copolymer with ethylene (block, random),
These mixtures and the like can be used.

According to a third aspect of the present invention, in the method for producing a thermoplastic resin film according to the first or second aspect, an elastic roll is disposed so as to face the cooling roll with the metal belt interposed therebetween. It is characterized in that a surface pressure of 0.01 to 20.0 MPa is applied between the cooling roll and the elastic roll.

The elastic roll may have at least a surface layer made of an elastic material. As the material of the elastic material, fluorine-based rubber, silicone-based rubber, urethane rubber,
Neoprene rubber, EPDM, etc. can be used. In these elastic materials, metal powder (eg,
Iron powder, copper powder, etc.). In addition, the thickness of the elastic material is set to obtain a good surface pressure by elastic deformation.
It is preferably 3 mm or more. The elastic roll may include an outermost layer made of metal or the like.

This surface pressure is adjusted by the tension of the metal belt. When the surface pressure is less than 0.01 MPa, it becomes difficult to prevent meandering of the belt and biting of air. Also, 20.0MP
If it exceeds a, problems tend to occur in the durability of the belt. Preferably, 0.01 to 1.0 MPa, more preferably 0.01 to
0.5 MPa. In the present invention, in order to cool the resin film by pressing the resin film in a plane with elastic deformation of the elastic material,
The cooling efficiency of the resin film increases.

According to a fourth aspect of the present invention, there is provided a method for producing a thermoplastic resin film according to any one of the first to third aspects, wherein the surface pressure acting time of the metal roll and the metal belt is equal to or less than 0.1.
1 to 10.0 seconds. If the surface pressure action time is shorter than 0.1 second, the effect of using the belt is lost.
On the other hand, if the time exceeds 10.0 seconds, in addition to the decrease in productivity, the sticking of the film to the belt becomes excessive and it becomes difficult to peel the film from the belt.

According to a fifth aspect of the present invention, there is provided a method for producing a thermoplastic resin film, comprising: a cooling roll in contact with a thermoplastic resin in a molten state; and a metal belt held by a part of an outer peripheral surface of the roll. A thermoplastic resin film manufacturing apparatus, wherein the thickness of the thermoplastic resin film is St,
When the thickness of the metal belt is Bt, Bt ≦ 10 × S
t, and 0.2 mm ≦ Bt ≦ 1.5 mm.

The cooling roll has only to have a metal layer at least at the outer periphery, and an elastic member may be provided inside the metal layer. The surface roughness Ra of the metal layer is preferably 0.5 μm or less in order to improve the surface gloss of the obtained film. As the material of the metal belt, stainless steel, carbon steel, titanium alloy, or the like can be used. Said B
The reason for limiting the range of t and the like are as described in the first invention.

[0017] The manufacturing apparatus according to the sixth invention of the present invention comprises a fifth device.
In the invention, the metal belt is a seamless endless belt. The seamless endless belt is, for example, using a seamless belt material in which a thin plate-shaped metal material is annularly continuous, and cutting the outer peripheral surface of the belt material to make the thickness of the entire belt constant. Can be manufactured.

The manufacturing apparatus according to the seventh aspect of the present invention comprises:
Alternatively, in the sixth invention, the metal belt has a surface roughness Ra
Is 0.5 μm or less. When the surface roughness Ra exceeds 0.5 μm, the surface gloss of the obtained film decreases.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a thermoplastic resin film 11 and an apparatus therefor according to the present embodiment will be described with reference to FIG. First, the configuration of a manufacturing apparatus used in the manufacturing method of the present embodiment will be described. This manufacturing apparatus is equipped with an extruder T
Seamless metal endless belt wound between die 12 and first and second cooling rolls 13 and 14
15 and the first cooling roll 13 with the endless belt 15 interposed therebetween.
Third cooling roll 16 arranged to face
And a roll 17 provided in the vicinity of the second cooling roll 14. Before the first cooling roll 13 in the endless belt 15, a fourth cooling roll 21 is further provided.
Is provided.

The surface of the first cooling roll 13 is coated with an elastic material 18. The elastic member 18 has a hardness (based on JIS K6301 A type) of 95 degrees or less and a thickness of 3 mm or more. The fourth cooling roll 21 is for cooling the endless belt 15. This cooling roll
The reference numeral 21 may be used to adjust the tension of the endless belt 15.

The metal endless belt 15 is made of stainless steel or the like, and has a mirror surface having a surface roughness Ra of 0.5 μm or less. And the obtained thermoplastic resin film 11
When the thickness of the endless belt 15 is Bt, the thickness of the endless belt 15 is set to Bt ≦ 10 × St and 0.2 mm ≦ Bt ≦ 1.5 mm. At least one of the first and second cooling rolls 13 and 14 has a rotating shaft 19 connected to a rotation driving means (not shown). The second, third and fourth cooling rolls
14, 16, and 21 are made of metal and have a surface roughness Ra of 0.5 μm.
m.

The third cooling roll 16 is made of a resin film
11 contacts the first cooling roll 13 via the endless belt 15, and the endless belt 15
It is provided so as to embrace the resin film 11 pressed to the side. That is, the endless belt 15 and the resin film 11 in close contact with the endless belt 15
Meandering around a part of the outer peripheral surface of the cooling roll 16.

A roll 17 provided in the vicinity of the second cooling roll 14 guides the resin film 11 so that the resin film 11 is pressed against the second cooling roll 14 via an endless belt 15. is there. Among the cooling rolls, the third and fourth cooling rolls 16 and 21 are provided with a temperature adjusting means (not shown) of a water-cooling type or the like capable of adjusting the temperature of the surface. The other cooling rolls 13 and 14 are not particularly provided with a temperature adjusting means, but may be provided.

Next, a method for manufacturing the thermoplastic resin film 11 of the present embodiment using the above-described manufacturing apparatus will be described. First, the third cooling roll 16 and the fourth cooling before this are maintained so that the surface temperatures of the endless belt 15 and the third cooling roll 16 which are in direct contact with the molten resin 11A are kept at 50 ° C. or less and above the dew point. The temperature of the roll 21 is controlled. A pellet made of polypropylene is prepared as a raw material of the resin film 11 to be supplied to the extruder.

After the raw materials are put into an extruder and melted and kneaded, the molten thermoplastic resin film 11A extruded from the T-die 12 is placed on a first cooling roll 1A.
The third and third cooling rolls 13 and 16 are introduced into the endless belt 15 and the third cooling roll 16 at substantially the same time so as to contact the endless belt 15 and the third cooling roll 16. The molten resin 11A is cooled to 50 ° C. or less between the cooling rolls 13 and 16 and solidified to form a film 11. At this time, the elastic material 18
And the third cooling rolls 13, 16 are elastically deformed so as to be compressed by the pressing force between the rolls 13, 16, and the elastic material 18 is formed of the resin film 11 at an angle θ1 from the center of the elastically deformed rolls 13, 16. Are in the form of planar pressing by both rolls 13 and 16. The surface pressure at this time is 0.1 MPa to 20 MPa.

Subsequently, the resin film 11 is pressed against the third cooling roll 16 by the endless belt 15 to press it.
Cool to below 50 ° C. The resin film 11 pressed against the cooling roll 16 by the endless belt 15 is
The resin film 11 is pressed by the endless belt 15 and the third cooling roll 16 in a plane at this holding angle θ2. The surface pressure at this time is 0.01 MPa to 0.5 MPa.
The surface pressure acting time at the angle θ1 part and the angle θ2 is 0.1.
~ 10.0 seconds.

Subsequently, the second cooling roll 14 is attached while the thermoplastic resin film 11 is in close contact with the endless belt 15.
Side, and after further cooling, the thermoplastic resin film 11 is wound around a predetermined roll.

[0028]

【Example】

Example 1 In the above embodiment, the thermoplastic resin film 11 was manufactured under specific conditions as follows. Extruder diameter: 90 mm, T-die width: 800 mm. The diameter of the first to fourth rolls ... 1000 mm. Endless belt …… Stainless steel, Ra: 0.2 μm,
Width: 1200mm, length: 8.0m, thickness (Bt): 0.5mm.

Surface temperature of the endless belt and roll in contact with the film: 15 ° C. Surface pressure at the angle θ1 part: 0.5 MPa. Action time of surface pressure on the film at the angles θ1 and θ2…
... 5 seconds. Endless belt moving speed ... 20m / min. Thermoplastic resin: polypropylene (Polypropylene F200)
SP, manufactured by Idemitsu Petrochemical Co., Ltd.). Thermoplastic resin film: thickness (St): 0.1 mm, width: 6
40mm.

According to this embodiment, the thickness of the endless belt (Bt) and the thickness of the thermoplastic resin film (St) are
Since the requirements of t ≦ 10 × St and 0.2 mm ≦ Bt ≦ 1.5 mm were satisfied, no air entrapment phenomenon was observed when the thermoplastic resin film 11 was pressed in a planar manner. Also,
The resulting thermoplastic resin film 11 was highly transparent, high gloss, and had a good appearance.

Example 2 The procedure was the same as in Example 1, except for the following conditions. Endless belt: thickness (Bt): 1.0 mm. Thermoplastic resin film: thickness (St): 0.2 mm. Even in this example, no air entrapment phenomenon was observed during the production, and the thermoplastic resin film 11 having high transparency, high gloss, and good appearance was obtained.

Example 3 The procedure was the same as in Example 1, except for the following conditions. Endless belt: thickness (Bt): 1.5 mm. Thermoplastic resin film: thickness (St): 0.2 mm. Even in this example, no air entrapment phenomenon was observed during the production, and the thermoplastic resin film 11 having high transparency, high gloss, and good appearance was obtained.

Comparative Example 1 The procedure of Example 1 was repeated, except that the following conditions were different. Endless belt: thickness (Bt): 1.0 mm. Thermoplastic resin film: thickness (St): 0.05 mm. According to this comparative example, since the requirement of Bt ≦ 10 × St according to the present invention was not satisfied, an air entrapment phenomenon occurred during the production, and the obtained thermoplastic resin film had transparency and glossiness. And the appearance was poor.

Comparative Example 2 The procedure of Example 1 was repeated, except that the following conditions were different. Endless belt: thickness (Bt): 1.7 mm. Thermoplastic resin film: thickness (St): 0.2 mm. Also in the case of this comparative example, since the relationship between Bt and St according to the present invention was not satisfied, air entrapment phenomena due to touch failure and defective phenomena such as bank marks occurred during manufacturing, and the obtained thermoplasticity was obtained. The resin film was poor in appearance.

[0035]

According to the method and apparatus for producing a thermoplastic resin film of the present invention, it is possible to prevent the occurrence of poor appearance due to air entrapment or the like, and to obtain a highly transparent and highly glossy film.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus used in a method for producing a thermoplastic resin film according to an embodiment of the present invention.

[Explanation of symbols]

 11A Molten resin 11 Thermoplastic resin film 12 Extruder die 13 First cooling roll as elastic roll 15 Metal endless belt as metal belt 16 Third cooling roll as cooling roll 18 Elastic material

Claims (7)

[Claims] 1. A method for producing a thermoplastic resin film in which a molten thermoplastic resin is cooled and formed into a thermoplastic resin film while being planarly pressed and sandwiched between a cooling roll and a metal belt. When the thickness of the thermoplastic resin film is St and the thickness of the metal belt is Bt, Bt ≦ 10 × St, and 0.2 m
A method for producing a thermoplastic resin film, wherein m ≦ Bt ≦ 1.5 mm is set. 2. The method for manufacturing a thermoplastic resin film according to claim 1, wherein the thermoplastic resin is polypropylene. 3. The method for producing a thermoplastic resin film according to claim 1, wherein an elastic roll is disposed so as to face the cooling roll with the metal belt interposed therebetween. A method for producing a thermoplastic resin film, wherein a surface pressure of 0.01 to 20.0 MPa is applied between the films. 4. The method for producing a thermoplastic resin film according to claim 1, wherein the surface pressure acting time between the metal roll and the metal belt is 0.1 to 1
A method for producing a thermoplastic resin film, wherein the time is 0.0 second. 5. An apparatus for producing a thermoplastic resin film, comprising: a cooling roll in contact with a thermoplastic resin in a molten state; and a metal belt held by a part of an outer peripheral surface of the roll. When the thickness of the resin film is St and the thickness of the metal belt is Bt, Bt ≦ 10 × St, and 0.2 m
An apparatus for producing a thermoplastic resin film, wherein m ≦ Bt ≦ 1.5 mm is set. 6. The apparatus for producing a thermoplastic resin film according to claim 5, wherein said metal belt is a seamless endless belt. 7. The apparatus for producing a thermoplastic resin film according to claim 5, wherein the surface roughness Ra of the metal belt is 0.5 μm or less.