JPH0533134B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a thermoplastic resin film, and more specifically, the present invention relates to a method for producing a thermoplastic resin film. This invention relates to a film manufacturing method.

[Prior art and its problems] When forming a film by melt extrusion using a flat die such as a T-die, especially when taking off the film at high speed, neck-in, stretch breakage, etc. occur, and formability becomes unstable. This has caused various problems such as:

Among the various problems mentioned above, regarding the net-in phenomenon, we used the air chamber method, in which compressed air is jetted out from a slit parallel to the chill roll, and the resin film extruded from the die is pressed onto the chill roll, and a Soroban bead-shaped roller is used. This problem has been solved by a pressure bonding method in which both ends of the resin film are pressed against chill rolls.

However, these methods do not provide any solution to the neck-in development that occurs from the die opening to the chill roll, and the pressure bonding method described above is difficult to apply to thermoplastic resins with high melting points. moreover,
In the air chamber method described above, when the resin film is taken off at high speed, the molding stability is fair, but
Stretch breakage occurs.

For this reason, there is a method in which both ends of the extruded resin film are brought into contact with the circumferential side of the cooling pipe over the entire length of the resin film between the die and the chill roll (see Japanese Patent Publication No. 12496/1983), A method has been proposed in which a jet of cooling gas is applied over the entire width of the membrane (see Japanese Patent Application Laid-open No. 59-29125, Japanese Patent Application Laid-open No. 79731, etc.).

However, in the above method, since the cooling pipe is brought into direct contact with the extruded resin film,
The method does not avoid operational constraints, and the method
Although the molding stability is good, since both ends of the extruded resin film are rapidly cooled as in the above method, stretching breaks occur during high-speed take-off.

This invention has been made based on the above circumstances.

That is, an object of the present invention is to produce a thermoplastic resin film that has good molding stability, less occurrence of stretch breakage and neck-in, and has excellent operability in a method of extruding molten resin from a flat die to mold the film. The purpose is to provide a method. Another object of the present invention is to provide a method for producing particularly ultra-thin films such as polycarbonate and high-density polyethylene, which have high melt viscosity and frequently suffer from stretching breakage during high-speed take-off, without any stretching breakage. It is about providing.

[Means for Solving the Problems] The present invention for solving the problems described above provides a film manufacturing method in which a melt-kneaded thermoplastic resin is extruded from a flat die and cooled and solidified. This method of manufacturing a thermoplastic resin film is characterized in that the resin film up to the roll is cooled with a cooling gas except for both end portions of the resin film.

The method of this invention will be explained below with reference to the drawings.

As shown in FIG. 1, in the method according to the present invention, a take-up guide roll 2 is arranged at a predetermined distance from the resin extrusion port of a flat die 1, and the resin film 3 extruded from the flat die 1 is transferred to the take-up guide roll 2. The gas outlet 4 is disposed facing the surface of the resin film 3 between the flat die 1 and the take-up guide roll 2, and the resin film 3 except for both ends of the resin film 3 is removed. Cooling gas is blown onto the surface of the film 3 from the gas outlet 4 to cool the resin film 3.

Here, the thermoplastic resin includes, for example, polyolefins such as polycarbonate resin, polyester-polycarbonate resin, polyarylate resin, polysulfone resin, polyetherimide resin, polyethersulfone resin, polyallylsulfone resin, and high-density polyethylene. Examples include resins, polystyrene resins, polyvinyl chloride resins, polymethyl methacrylate resins, and cellulose acetate resins.

Among these, thermoplastic resins, such as low-density polyethylene and linear low-density polyethylene, which generally have good molding stability and less occurrence of stretch breakage, have a higher melt viscosity and are less prone to stretch breakage. Polycarbonate-based resins, high-density polyethylene, and the like, which have a large amount of polycarbonate, are preferable because they can sufficiently exhibit the effects of the present invention.

The thermoplastic resin is melt-kneaded using an extrusion molding machine such as a single-screw extruder, twin-screw extruder, or disk-type extruder, and then extruded from a flat die 1. Here, flat die 1 is T
- die, I-die, etc., and the die format may be either a straight manifold type or a coat hanger type. Note that a vent type extruder can also be used as the extrusion molding machine.

Further, when extruding the resin from the resin extrusion port of the flat die 1, it is preferable to extrude the resin with the amount of extrusion at both ends of the resin extrusion port being larger than the amount of extrusion at the center. In order to make the amount of extrusion at both ends of the resin extrusion port larger than the amount of extrusion from the center, the opening degree of the die lip at the resin extrusion port may be made larger than the die lip at the center. The set temperature at both ends of the mouth may be higher than the set temperature at the center.

The arrangement interval (air gap AG) of the take-up guide roll 2 with respect to the flat die 1 is:
Usually 40 to 500 mm, preferably 50 to 300 mm.
If the air gap AG is shorter than 40 mm, the deformation of the resin film 3 during take-off will be large and the film thickness will not be uniform. Furthermore, even if the air gap AG is made larger than 500 mm, there is no particular technical effect proportional to the larger size. In this invention, the air gap AG can be made larger than the conventional air gap AG, and the reason why such a large air gap AG is possible is because the air is cooled by the gas blown from the gas outlet 4. be.

The gas outlet 4 may be a circular hole, a rectangular horizontally elongated slit, or a small hole arranged along the width direction of the resin film 3. An air knife having a slit-like orifice, for example, can be used as a device having such a gas outlet 4.

What is important in this invention is that the air gap
On the surface of the resin film 3 between AG, the surface of the resin film 3 excluding both end portions of the resin film 3 is
It is cooled with cooling gas from. In other words, in the direction parallel to the center line of the take-up guide roll 2, both ends of the resin film 3 toward the center of the resin film 3 up to a predetermined distance E from the end of the resin film 3 are not cooled with cooling gas. The resin film 3 other than both end portions is cooled.

The predetermined distance E is usually 10 to 100 mm, particularly preferably 20 to 80 mm from the end of the resin film 3. If the distance E is smaller than 10 mm, the resin film will be cooled from both ends, causing film breakage from the end faces.
On the other hand, if the distance E is greater than 100 mm, this is undesirable since it is disadvantageous in obtaining a uniform effective width of the film.

In addition, the parts of the resin film 3 that are cooled with cooling gas are as follows:
As shown in FIG. 1, it may be a region corresponding to the center line of the take-up guide roll 2, excluding both end portions of the resin film 3 and the center portion of the resin film 3; As shown in FIG. 2, it may be a band-shaped portion 5 that is parallel to the center line of the take-up guide roll 2 and excludes both end portions of the resin film 3. Furthermore, such a cooling part of the resin film 3 is
It may be on one side of the resin film 3 or on both sides of the resin film 3. Therefore, the gas jet ports 4 may be arranged so as to face both sides of the resin film 3, as shown in FIG. Furthermore, a plurality of gas jet ports may be arranged on one or both surfaces of the resin film 3 along the direction in which the resin film 3 is taken up.

Further, the distance L between the gas outlet 4 and the surface of the resin film 3 is usually 5 mm to 500 mm, particularly preferably 10 to 400 mm.

Distance L between this gas outlet 4 and the surface of the resin film 3
If it is smaller than 5 mm, uniform cooling of the resin film 3 will be difficult, and if it is larger than 500 mm, the cooling effect by gas blowing will not be sufficient.

The gas blown from this gas outlet 4 is as follows:
Examples include air, nitrogen, carbon dioxide gas, etc.

The outlet speed of this gas is usually 0.1~
50m/sec is appropriate. Note that in order to prevent excessive cooling of both ends of the resin film 3, suction equipment for the ejected gas may be provided.

The take-up guide roll 2 has, for example, a hard chrome plated surface and has water or the like circulated inside.
A conventionally known cooling roll can be used, or a simple roller may be used.

The take-up speed of the film cooled by the cooling gas is usually 10 m/min or more.

[Function] According to the method of the present invention having the above configuration, the thermoplastic resin in a melted and kneaded state extruded from the flat die 1 is taken in the form of a film, and the gas blown from the gas outlet 4 and the taken-out It is cooled and solidified by the guide roll 2 and wound up into a film.

At this time, since the cooling gas blown from the gas outlet 4 cools the surface of the resin film 3 except for both end portions, the both end portions of the resin film 3 are not cooled rapidly. Therefore, even if the resin film 3 is taken off at high speed, no stretching breakage occurs. Furthermore, since the resin film 3 between the flat die 1 and the take-up guide roll 2 is cooled, the net-in is reduced and the molding stability is improved.

[Effects] According to the present invention, the resin film between the flat die and the take-up guide roll is cooled with cooling gas, and both ends of the resin film are not cooled during cooling, which improves molding stability and reduces stretching breakage. It is possible to prevent the occurrence of and reduce netquin. Since stretching breakage can be prevented, the resin film can be taken off at high speed, thereby making it possible to form an extremely thin film. Further, the method of the present invention can form ultra-thin films without any stretching breakage, even when using polycarbonate resins, high density polyethylene, etc., which conventionally tend to break down when drawn at high speeds.

Since the method of the present invention cools the resin film by spraying cooling gas, there are no restrictions on the equipment or operation, and the operability is also good.

[Example] Next, examples and comparative examples of the present invention will be shown.

Example 1 Polycarbonate resin [manufactured by Idemitsu Petrochemical Co., Ltd., Idemitsu Polycarbonate A-3000, molecular weight 30000],
Using a 50mmφT-die extrusion device (die width 550mm, die lip opening 0.6mm), the resin temperature at the die exit was 274.
It was extruded under the conditions of ℃, discharge rate of 15.6 kg/hr, and air gap of 50 mm. At this time, it should be on the opposite side of the take-up guide roll with the resin film inside, 25 mm away from the die exit toward the take-up guide roll (approximately 25 mm from the edge of the resin film), and 50 mm away from the resin film surface.
Air was blown onto the surface of the resin film using an air knife with a width of 430 mm and a lip opening of 1 mm placed at a distance of mm. It can be molded with good molding stability and without stretching breakage at up to a take-up speed of 160 m/min, with a thickness of 2.5 μm,
A uniform film with a width of 400 mm (width variation of 10 mm) was obtained.

Example 2 A pair of air vents were placed 70 mm inward from both ends of the die toward the center of the die (approximately 60 mm from the edge of the resin film), 10 mm away from the die exit toward the take-up guide roll, and 50 mm away from the surface of the resin film. A film was molded in the same manner as in Example 1, except that air was blown from a nozzle (6 mm x 2 mm) at a wind speed of 35 m/sec. Good molding stability up to a take-up speed of 120 m/min, no stretching breakage, and a thickness of 3.3μ
A uniform film with a width of 380 mm (fluctuation width of 40 mm) was obtained.

Example 3 120mm inward from both ends of the die toward the center of the die, 35mm from the die exit toward the take-up guide roll
(approximately 65mm from the edge of the resin film), 50mm from the surface of the resin film
A film was molded in the same manner as in Example 2, except that a pair of air nozzles were added at separate positions to blow air. It has good forming stability up to a take-up speed of 140 m/min, and can form films without any stretching breakage.
A uniform film with a thickness of 2.8 μm and a width of 400 mm (fluctuation width of 20 mm) was obtained.

Comparative Example 1 The procedure of Example 1 was repeated except that air was not blown. As a result, molding instability occurred at a take-up speed of 60 m/min, and molding could not be performed.

Comparative Example 2 The width of the air knife was 600 mm, and the operation was carried out in accordance with Example 1, except that air was blown over the entire width of the extruded resin film, resulting in a take-up speed of 50 m/min.
Stretching breakage occurred at 10 min, and it was not possible to obtain a thin film. Furthermore, the molding stability was good.

Example 4 The resin temperature at the die exit was 272℃, and the discharge amount was
Extrude under conditions of 10Kg/hr, and move the air nozzle 70mm inward from both ends of the die toward the center of the die.
10mm from the die exit toward the take-up guide roll (approximately 60mm from the edge of the resin film), and further from the resin film surface.
A pair of first air nozzles are placed 50mm apart, and then 120mm from both ends of the die toward the center of the die.
Inward, from the die exit towards the take-up guide roll.
A film was molded in the same manner as in Example 2, except that a pair of second air nozzles were provided at a distance of 35 mm (approximately 75 mm from the end of the resin film) and 50 mm from the surface of the resin film, and air was blown from each nozzle. The film has good forming stability up to a take-up speed of 100 m/min, and can be formed into a film with no stretching breakage, with a thickness of 2.5 μm.
A uniform film with a width of 420 mm (fluctuation width of 10 mm) was obtained.

Example 5 High-density polyethylene [manufactured by Idemitsu Petrochemical Co., Ltd., Idemitsu Polyethylene] was used instead of polycarbonate resin.
440M, density 0.954g/ ^cm3 , MI0.9g/10min,
Mw/Mn=4] to adjust the resin temperature at the die exit.
The procedure of Example 3 was repeated except that the temperature was 223° C., and a film with good molding stability and no stretch breakage could be molded at a take-up speed of 100 m/min.

[Brief explanation of the drawing]

FIG. 1 is an explanatory front view of an apparatus for implementing the method of this invention, FIG. 2 is an explanatory side view of the apparatus shown in FIG. 1, and FIG. 3 is an explanatory view of another apparatus for implementing the method of this invention. 4 is a front view and a side view of the apparatus shown in FIG. 3. 1...Flat die, 2...Take-up guide roll, 3...Resin film, 4...Gas spout.

Claims (1)

[Scope of Claims] 1. A method for producing a film in which melted and kneaded thermoplastic resin is extruded from a flat die and cooled and solidified, wherein the resin film from the flat die to the take-up guide roll is heated with cooling gas except for both end portions of the resin film. A method for producing a thermoplastic resin film, which comprises cooling. 2. The gap between the flat die and the take-up guide roll is 40 to 500 mm, and both end portions of the resin film are 10 mm from the ends of the resin film toward the center of the resin film.
The method for producing a thermoplastic resin film according to claim 1, wherein the thermoplastic resin film has a size of up to 100 mm. 3. The method for producing a thermoplastic resin film according to claim 1 or 2, wherein the cooling gas cools a portion of the resin film other than both end portions in the width direction of the resin film. . 4. The heat treatment according to claim 1 or 2, wherein the cooling gas cools the resin film in the width direction of the resin film except for both end portions of the resin film and the center portion of the resin film. A method for producing a plastic resin film. 5. The method for producing a thermoplastic resin film according to any one of claims 1 to 4, wherein the thermoplastic resin is either a polycarbonate resin or a high-density polyethylene.