JP6822884B2 - Film manufacturing method - Google Patents

Description

The present invention relates to a method for producing a film made of a thermoplastic resin composition.

Conventionally, as a method for producing a film, a melt extrusion method is known in which a thermoplastic resin composition, which is a raw material for a film, is extruded into a film from a die in a molten state by using a melt extruder. Further, in order to reduce the thickness unevenness and the surface unevenness of the film obtained by the melt extrusion method and obtain the surface smoothness, the film-like thermoplastic resin composition extruded from the die is sandwiched between a pair of rolls. , A method of molding into a film is known (see, for example, Patent Document 1).

However, as shown in FIGS. 6A and 6B, if the foreign matter 114 adheres to the surface of the roll 111, the film 113 is sandwiched and molded by the pair of rolls 111 and 112. The shape of the foreign matter 114 is transferred to the film 113, and as shown in FIG. 6C, a dent defect 113a is generated in the film 113. At this time, since the roll 111 continues to rotate at a constant cycle, unless the foreign matter 114 falls off from the surface of the roll 111, dent defects 113a are periodically and continuously generated, and the quality of the film 113 is greatly impaired.
In particular, in the melt extrusion method, since the film 113 is soft at a high temperature, a dent defect 113a may occur even if the foreign matter on the rolls 111 and 112 is minute (several μm in height).

Therefore, the rolls 111 and 112 may be equipped with a roll cleaner device for removing foreign matter adhering to the roll surface.

WO2013 / 038866

However, the dent defect 113a in the film 113, which is a product, may be very minute, and the dent defect 113a may often be missed in the inspection by a visual or in-line film inspection device.
When such a detection omission occurs, it is difficult to determine whether or not the surfaces of the rolls 111 and 112 have been sufficiently cleaned.

Further, since cleaning the entire surface of the rolls 111 and 112 has a large workload, it is desirable to identify the position of foreign matter adhering to the rolls 111 and 112 from the dent defect 113a in the film 113.
By doing so, it is possible to clean not the entire surface of the rolls 111 and 112 but only the portion on the rolls 111 and 112 where foreign matter is likely to adhere, and the work load is reduced.
However, if the dent defect 113a is not detected, it is difficult to accurately identify the position where the foreign matter is attached on the rolls 111 and 112 in the width direction.

Under these circumstances, in the method of sandwiching a film-like thermoplastic resin composition extruded from a die between a pair of rolls and forming the film, dent defects in the film caused by minute foreign substances on the rolls are found. It is desired to reduce detection omissions.

An object of the present invention is to provide a film manufacturing method capable of easily detecting a dent defect caused by a minute foreign substance on a roll and efficiently cleaning the roll based on the dent defect detection information. And.

Prior to the production of the product film, the present inventors perform an inspection for detecting a dent defect caused by a foreign substance on the roll, and optimize the molding conditions of the film-like sample in the inspection to perform a dent. We have found that the visibility of defects is improved and that the roll can be efficiently cleaned based on the detection information of dent defects, and the present invention has been completed.

That is, the present invention
(I) A method for producing a film made of a thermoplastic resin composition.
An inspection including extruding the molten thermoplastic resin composition from a die as a film-like melt, sandwiching it with a pair of rolls to form a film-like sample, and then detecting defects on the surface of the sample.
Includes product film production by extruding a molten thermoplastic resin composition from a die as a film-like melt, sandwiching it with a pair of rolls and molding it into a film.
The inspection is done before the production of the product film,
If defects are detected, the surface of the roll is cleaned prior to product film production.
In the inspection, the temperature T1 of the thermoplastic resin composition extruded from the die is lower than the temperature T2 of the thermoplastic resin composition extruded from the die in the production of the product film.
(Ii) A method for producing a film made of a thermoplastic resin composition.
An inspection including extruding the molten thermoplastic resin composition from a die as a film-like melt, sandwiching it with a pair of rolls to form a film-like sample, and then detecting defects on the surface of the sample.
After extruding the molten thermoplastic resin composition from a die as a film-like melt, the product film is produced by sandwiching the film-like melt with a pair of rolls and molding the film into a film.
The inspection is done before the production of the product film,
If a defect is detected in the inspection and the defect is a periodic defect that occurs corresponding to the rotation cycle of the roll, the surface of the roll is cleaned before the production of the product film.
In the inspection, the temperature T1 of the thermoplastic resin composition extruded from the die is lower than the temperature T2 of the thermoplastic resin composition extruded from the die in the production of the product film.
(Iii) The method for producing a film according to (i) or (ii), wherein T1 is lower than T2 by 10 ° C. or more.
(Iv) When the glass transition temperature of the thermoplastic resin composition is Tg, Tg, T1 and T2 are the following 1) and 2):
1) Tg <T1 <Tg + 140 ° C,
2) T2 ≧ Tg + 140 ° C
A film manufacturing method according to any one of (i) to (iii), which satisfies the relationship of
(V) In the inspection, identify the surface where the defect occurred in the sample,
The method for producing a film according to any one of (i) to (iv), wherein the surface of the roll in contact with the defective surface of the pair of rolls is cleaned.
(Vi) The method for producing a film according to any one of (i) to (v), wherein the surface of the roll is cleaned by a roll cleaner provided in contact with the surface of the roll or in the vicinity of the surface of the roll. ,
(Vii) A roll cleaner is provided so that it can contact the surface of the roll.
A film manufacturing method according to (vi), wherein a cloth is arranged at a position in contact with the roll of the roll cleaner.
(Vii) The method for producing a film according to (vii), wherein a cleaning liquid is supplied to a cloth and the cleaning is performed in a wet manner.
(Ix) The method for producing a film according to any one of (i) to (viii), wherein the thermoplastic resin composition is an acrylic resin composition.
I will provide a.

According to the present invention, there is provided a method for producing a film, which can easily detect a dent defect caused by a minute foreign substance on a roll and efficiently clean the roll based on the dent defect detection information. Can be done.

It is a figure which shows a part of the structure of the film manufacturing apparatus schematically. It is a figure which shows typically the mode that the dent defect caused by the foreign matter on the roll occurs at the time of sandwich molding. It is a figure which shows the flowchart about the manufacturing method of the film which concerns on 1st Embodiment. It is a figure which shows the flowchart about the manufacturing method of the film which concerns on 2nd Embodiment. It is a figure which shows the flowchart about the manufacturing method of the film which concerns on 3rd Embodiment. It is a figure which shows the state of occurrence of the dent defect schematically.

Hereinafter, the method for producing a film according to the present embodiment will be described in detail with reference to the drawings. In FIG. 1, the extruder 10 is simplified and only the vicinity of the die 11 is shown.

<< Film manufacturing method >>
In the film manufacturing method, an inspection for detecting dent defects is performed before manufacturing the product film.
In the inspection, the thermoplastic resin composition melted by the extruder 10 is extruded from the die 11 as a film-like melt 13', sandwiched between a pair of rolls to form a film-like sample 13, and then the surface of the sample 13 is formed. Includes detecting the dent defect 13a of.

The pair of rolls is not particularly limited as long as the film-like melt 13'can be sandwiched and molded. The pair of rolls is typically a cast roll 14 and a touch roll 15. The cast roll 14 and the touch roll 15 will be described later.

When the dent defect 13a is detected in the inspection, the surface of the cast roll 14 and / or the touch roll 15 is cleaned before the production of the product film.

In the production of a product film, a thermoplastic resin composition melted by an extruder 10 is extruded from a die 11 as a film-like melt 16', and then sandwiched between a cast roll 14 and a touch roll 15 to form a film 16.
The temperature T1 of the film-like melt 13'in the inspection is lower than the temperature T2 of the film-like melt 16' that was melt-extruded in the production of the product film. The temperature T1 and the temperature T2 are the temperatures of the film-like melt 13'and the film-like melt 16'at the die outlet 12 of the die 11. T1 and T2 may be adjusted by temperature control in the extruder 10 or in the die 11, or by providing a temperature adjusting auxiliary means such as a heater or a cooler near the die outlet 12 and adjusting by the temperature adjusting auxiliary means. May be done. The temperature adjusting assisting means may be a contact type device or a non-contact type device.

The dent defect 13a in the sample 13 obtained by the inspection has a larger opening width X1 of the recess than the dent defect 16a of the product film 16 obtained in the production of the product film, and is easy to detect.
As shown in FIG. 2A, in the inspection, if the foreign matter 18 is attached to the cast roll 14, the shape of the foreign matter 18 is transferred to the sample 13 at the time of sandwich molding.
Here, the temperature T1 of the film-like melt 13'at the die outlet 12 during the production of the sample 13 is lower than the temperature T2 of the film-like melt 16'at the die outlet 12 in the film production. Therefore, at the time of sandwich molding, the temperature of the sample 13 is lower than the temperature of the product film 16, and the rigidity of the sample 13 is higher than the rigidity of the product film 16.
For the reasons described above, when the sample 13 and the foreign matter 18 come into contact with each other, the sample 13 is less likely to be deformed along the shape of the foreign matter 18, and the opening width X1 of the dent defect 13a becomes large.
As a result, in the sample 13, even when the foreign matter 18 is extremely small, the dent defect 13a can be easily detected because the opening width X1 of the recess of the dent defect 13a is large. For example, in the above inspection, it is easy to sufficiently detect the dent defect 13a visually.

On the other hand, as shown in FIG. 2B, in the product film production, the temperature T2 of the film-like melt 16'at the die outlet 12 is the film-like melt 13 at the die outlet 12 at the time of producing the sample 13. 'The temperature is higher than T1. Therefore, the rigidity of the product film 16 is lower than the rigidity of the sample 13 at the time of sandwich molding.
For the reasons described above, when the product film 16 and the foreign matter 18 come into contact with each other, the product film 16 is easily deformed along the shape of the foreign matter 18, and the opening width X2 of the dent defect 16a becomes small.
For this reason, it is difficult to detect a dent defect 16a having an opening with a very small width due to a very small foreign substance 18 in the conventional inspection of a dent defect 16a caused by a foreign substance using a product film. ..

As described above, before manufacturing the product film, the temperature T1 of the film-like melt 13'at the die outlet 12 is set to the temperature of the film-like melt 16'at the die outlet 12 at the time of manufacturing the product film 16. The dent defect 13a can be made conspicuous by producing the sample 13 by performing sandwich molding after setting the temperature lower than T2. As a result, in the inspection of the sample 13, the dent defect 13a can be detected with high accuracy and quickly.

When the dent defect 13a is detected, the position of the foreign matter adhering to the cast roll 14 and / or the touch roll 15 (for example, based on the information on the position where the dent defect 13a occurs in the sample 13) is detected. Width direction position) can be specified.

By determining which of the two main surfaces of the sample 13 the dent defect 13a has an opening, which of the cast roll 14 and the touch roll 15 the dent defect 13a is caused by a foreign substance is caused. Can be identified.
Further, by specifying the generation cycle of the dent defect 13a that occurs periodically and determining which of the outer peripheral lengths of the cast roll 14 and the touch roll 15 the specified generation cycle matches, the foreign matter is cast. It is possible to identify which of the roll 14 and the touch roll 15 is attached.
If it is possible to identify whether the dent defect 13a is caused by a foreign substance attached to either the cast roll 14 or the touch roll 15, it is considered that the foreign substance is attached to the cast roll 14 and the touch roll 15. Only need to be cleaned.

By removing the foreign matter 18 adhering to the cast roll 14 and / or the touch roll 15 based on the information on the position of the foreign matter thus obtained, the occurrence of the dent defect 16a in the product film 16 is remarkable. Can be suppressed.

Conventionally, the product film 16 has a dent defect 16a on the premise that the foreign matter 18 is attached to the cast roll 14 and / or the touch roll 15 in a state where the presence or absence of foreign matter is not known before the production of the product film. In many cases, the foreign matter 18 was removed by carefully increasing the number of steps so as not to occur.
Further, the foreign matter 18 on the cast roll 14 and / or the touch roll 15 was removed according to the occurrence situation of the dent defect 16a in the product film 16, but the dent defect 16a generated in the product film 16 was overlooked. It is easy to do so, and it is difficult to accurately determine whether or not the foreign matter 18 has been removed after cleaning.
For this reason, the productivity has been lowered due to problems such as the need to repeat cleaning, careful cleaning, and a large amount of waste of the product film 16.
On the other hand, in the film manufacturing method according to the present embodiment, the occurrence of the dent defect 16a in the product film 16 is easily suppressed, so that the loss of the product film 16 is small. Further, based on the detection result in the inspection, only the necessary parts of the cast roll 14 and / or the touch roll 15 may be cleaned. As a result, cleaning according to the result of the inspection may be performed more easily than in the conventional case, and the productivity is improved.

The dent defect 13a on the surface of the sample 13 may be detected visually or by using a defect inspection device. The defect inspection device acquires, for example, image data of the surface of the sample 13 and data such as shape and thickness, and detects the dent defect 13a on the sample 13 from these data.
The inspection of the sample 13 using the defect inspection device may be performed on the recovered sample 13, or may be performed in-line in the steps after the sandwich molding.
The inspection of the sample 13 is preferably performed visually because it is easy to detect the minute dent defect 13a with particularly high accuracy.
The dent defect 16a of the product film 16 can also be detected by the same method as the inspection of the sample 13 described above.

<First Embodiment>
Hereinafter, the first embodiment will be described with reference to the flowcharts shown in FIGS. 3 (a) and 3 (b).

First, as shown in FIG. 3A, the thermoplastic resin composition as a film raw material is supplied to the extruder 10, and the thermoplastic resin composition is melted by heating in the extruder 10. The molten thermoplastic resin composition is sent to a die 11 attached to the outlet side of the extruder 10, and is discharged as a film-like melt 13'from the die outlet 12 at the tip of the die in the molten state. At the die outlet 12, the temperature of the film-like melt 13'is controlled by T1. Then, the film-like melt 13'is sandwiched between the cast roll 14 and the touch roll 15 while applying pressure to smooth the surface thereof and form the sample 13 (step S1).

The cast roll 14 has a function of supporting the film-like melt 13'discharged from the die outlet 12 on the surface and cooling the film-like melt 13'. Further, the cast roll 14 also has a function of sandwiching the film-like melt 13'with the touch roll 15 while applying pressure to form a smooth film. The surface of the cast roll 14 is usually made of a hard material such as metal.
The touch roll 15 has a function of sandwiching the film-like melt 13'with the cast roll 14 while applying pressure to form a smooth film. In the touch roll 15, the surface of the roll made of an elastic body such as rubber is usually covered with a metal film.

Here, the temperature T1 is lower than the temperature T2, and is preferably 10 ° C. or more lower than the temperature T2, and more preferably 20 ° C. or more lower than the temperature T2, from the viewpoint of increasing the opening width X1 of the dent defect 13a of the sample 13. ..
Preferred conditions are appropriately set for the temperature T1 and the temperature T2 depending on the type and viscosity of the thermoplastic resin composition, the discharge amount thereof, the desired film thickness and the like.
For example, from the viewpoint of achieving both good detection of dent defects in sample 13 and production of product film 16 having excellent characteristics, when the glass transition temperature of the thermoplastic resin composition is Tg, Tg and T1 are used. , T2 and the following 1), and 2):
1) Tg <T1 <Tg + 140 ° C,
2) T2 ≥ Tg + 140 ° C,
It is preferable to satisfy the relationship of.
The relationship between Tg and the temperature T1 is more preferably Tg <T1 <Tg + 130 ° C. from the viewpoint that the opening width X1 of the dent defect 13a in the sample 13 can be easily increased.
Further, the relationship between Tg and the temperature T2 is preferably T2 ≧ Tg + 140 ° C., more preferably T2 ≧ Tg + 145 ° C., from the viewpoint of making the thickness of the film 16 uniform and suppressing the occurrence of dent defects 16a having a large opening width X2. , T2 ≧ Tg + 150 ° C. is particularly preferable.

The glass transition temperature Tg of the thermoplastic resin composition is calculated by the following measuring method. Using a differential scanning calorimetry device (DSC) SSC-5200 manufactured by Seiko Instruments, the sample (thermoplastic resin composition) was once heated to 200 ° C. at a rate of 25 ° C./min, held for 10 minutes, and held at 25 ° C./. After preliminary adjustment to lower the temperature to 50 ° C. at the rate of minutes, the measurement was performed while the temperature was raised to 200 ° C. at the rate of temperature rise of 10 ° C./min, and the integrated value was obtained from the obtained DSC curve (DDSC). The glass transition temperature is obtained from the maximum point.

Next, the presence or absence of a dent defect 13a on the surface of the sample 13 obtained by sandwich molding is detected (step S2). Since the dent defect 13a generated in the sample 13 has a larger opening width X1 than the dent defect 16a generated in the product film 16, the inspection using the sample 13 is a visual or defect inspection as compared with the inspection using the product film 16. The dent defect 13a can be detected with high accuracy and quickly by an apparatus or the like.

As for the conditions other than the temperature in the sandwich molding, preferable conditions are appropriately set depending on the type of the thermoplastic resin composition, its viscosity, the discharge amount, the desired film thickness, etc., and the conditions that do not hinder the good detection of the dent defect 13a. If so, there is no particular limitation. The conditions may be the same as those set at the time of product film production so that the transition from inspection to product film production can be facilitated.

Next, when a dent defect 13a is detected on the sample 13 (Yes in step S2), the cast roll 14 and / or the touch roll 15 is cleaned (step S3). Then, in order to produce the product film 16, the temperature of the molten film-like thermoplastic resin composition at the die outlet 12 is raised from T1 to T2 for melt extrusion, and then sandwich molding is performed to produce the product film 16. (Step S4).

In the product film production (step S4), first, the temperature of the film-like melt 16'to be melt-extruded from the die 11 of the extruder 10 is raised from T1 to T2 by adjusting the temperature of the die 11, for example. .. After the temperature of the film-like melt 16'reaches T2, the product film 16 is obtained by sandwiching the film-like melt 16'with the cast roll 14 and the touch roll 15 and molding the film-like melt 16'.

On the other hand, when the dent defect 13a is not detected on the sample 13 (No in step S2), it is determined that no foreign matter is attached to the cast roll 14 and / or the touch roll 15, and cleaning is not performed. The product film 16 is manufactured (step S4).

At this time, the entire surface of the cast roll 14 and the touch roll 15 may be cleaned, but for example, if the width direction position of the roll requiring cleaning is determined from the width direction position of the dent defect 13a and cleaned. Good. As a result, only the necessary parts on the cast roll 14 and the touch roll 15 can be cleaned, which is efficient.

As the sandwich molding conditions, preferable conditions are appropriately set depending on the type of the thermoplastic resin composition, its viscosity, the discharge amount, the desired film thickness, and the like.
When acquiring the product film 16, the surface temperatures of the cast roll 14 and the touch roll 15 shall be Tg-70 ° C. or higher and Tg or lower from the viewpoint of controlling the surface properties of the product film 16 to be good. Is preferable, Tg-60 ° C. or higher and Tg-10 ° C. or lower are more preferable, and Tg-50 ° C. or higher and Tg-20 ° C. or lower are particularly preferable.
When the sample 13 is obtained, if the surface temperature of the cast roll 14 and the touch roll 15 is Tg-70 ° C. or higher, the film-like melt 13'is sandwiched immediately after the roll landing and is cooled and solidified at the same time. It is preferable because the surface property of the film 13 can be controlled.
Also when the sample 13 is obtained, the surface temperature of the cast roll 14 and the touch roll 15 is preferably Tg-70 ° C. or higher and Tg or lower, more preferably Tg-60 ° C. or higher and Tg-10 ° C. or lower, and Tg- 50 ° C. or higher and Tg-20 ° C. or lower are particularly preferable.
When the surface temperature of the cast roll 14 and the touch roll 15 is Tg or less, the film-like melt 13'or the film-like melt 16' is conveyed from the cast roll 14 to a cooling roll (not shown) downstream. It is also preferable from the viewpoint that the film-like melt 13'or the film-like melt 16'does not adhere to the cast roll 14 and film surface defects (peeling patterns) at the time of peeling can be suppressed.

As shown in FIG. 3B, the cast roll 14 and / or the touch roll 15 may be cleaned before the inspection (step S0). This cleaning is usually performed over the entire width direction of the cast roll 14 and the touch roll 15. However, since the presence or absence of foreign matter is detected in the inspection after step S2, this cleaning can be simpler than the conventional cleaning that does not include the inspection performed before manufacturing the product film.

As described above, according to the first embodiment, the foreign matter on the cast roll 14 and / or the touch roll 15 can be removed with high accuracy and quickly in the inspection, so that the dent defect 16a in the product film 16 is remarkably generated. It can be suppressed. That is, according to the first embodiment, foreign matter on the cast roll 14 and the touch roll 15 can be detected with high accuracy and quickly in the inspection, so that the cleaning of the cast roll 14 and / or the touch roll 15 can be performed as compared with the conventional case. It is possible to produce the product film 16 in which the occurrence of the dent defect 16a is suppressed while making it possible to reduce the work load and the work time with high productivity.

<Second embodiment>
Hereinafter, the second embodiment will be described with reference to FIGS. 4 (a) and 4 (b). The same steps as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the second embodiment, the cast roll 14 and / or the touch roll 15 is cleaned until the dent defect 13a is no longer detected in the sample 13. Specifically, as shown in FIG. 4A, after the thermoplastic resin composition is melt-extruded and sandwiched and molded in the sample 13 (step S1), a dent defect 13a on the surface of the sample 13 is detected. Detection is performed (step S2). Then, when the dent defect 13a is detected in the sample 13 (Yes in step S2), the cast roll 14 and / or the touch roll 15 is cleaned (step S3).

The sandwich forming (step S1) and the dent defect detection (step S2) are repeated until the dent defect 13a is no longer detected (No in step S2). When the dent defect 13a is no longer detected in the sample 13 (No in step S2), the temperature of the molten film-like thermoplastic resin composition at the die outlet 12 is raised from the temperature T1 to T2 to produce the product film 16. (Step S4).

In the second embodiment, since the dent defect detection (step S2) is assumed a plurality of times, the dent defect 13a may be automatically detected by using a defect inspection device instead of visually.
When the dent defect 13a is detected by using the defect inspection device, when the number of steps S2 exceeds a predetermined number, a defect due to a factor other than foreign matter on the cast roll 14 and / or the touch roll 15 is detected. It may be determined that there is a possibility that the device may exist, a notification to that effect is given, and the device may be stopped in step S2.

Further, as shown in FIG. 4B, the cast roll 14 and / or the touch roll 15 may be cleaned before the inspection as in the first embodiment (step S0). As described above, since the presence or absence of foreign matter is detected in the inspection after step S2, this cleaning can be simpler than the conventional cleaning that does not include the inspection performed before the product film 16 is manufactured.

As described above, according to the second embodiment, it is confirmed whether or not the foreign matter 18 has been removed from the cast roll 14 and / or the touch roll 15 by cleaning because the dent defect 13a is not detected in the sample 13, and the product Since the process shifts to film production, it is possible to reliably prevent the film 16 from having dent defects.

<Third embodiment>
Hereinafter, the third embodiment will be described with reference to FIGS. 5 (a) and 5 (b). The same steps as those in the first embodiment are designated by the same reference numerals in the drawings, and the description thereof will be omitted.

In the third embodiment, when the dent defect 13a is detected in the sample 13, it is determined whether or not the defect is a defect that occurs periodically, and the foreign matter on the cast roll 14 and / or the touch roll 15 is determined. Determine if removal of 18 is necessary.
Specifically, as shown in FIG. 5A, after the thermoplastic resin composition is melt-extruded and sandwiched and molded in the sample 13 (step S1), the dent defect 13a on the surface of the sample 13 is detected. A certain defect is detected (step S2-1). Then, when the dent defect 13a is detected in the sample 13 (Yes in step S2-1), the dent defect 13a is a periodic defect that occurs corresponding to the rotation cycle of the cast roll 14 and / or the touch roll 15. (Step S2-2).
When the dent defect 13a is not detected in the sample 13 (No in step S2-1), the temperature of the molten film-like thermoplastic resin composition at the die outlet 12 is changed from T1 to T2 as in the second embodiment. The product film 16 is manufactured by raising the temperature to (step S4).

When the detected dent defect 13a is determined to be a periodic defect (Yes in step S2-2), it is determined that foreign matter is attached to the cast roll 14 and / or the touch roll 15, and the cast roll Cleaning of the 14 and / or the touch roll 15 is performed (S3).
On the other hand, when it is determined that the dent defect 13a is not a periodic defect (No in step S2-2), the foreign matter adhering to the cast roll 14 and / or the touch roll 15 is used to produce the sample 13. It is highly probable that it will no longer be present on the cast roll 14 and / or the touch roll 15 later. In this case, it is highly probable that the foreign matter 18 on the cast roll 14 and / or the touch roll 15 does not need to be removed. Therefore, the temperature of the molten film-like thermoplastic resin composition at the die outlet 12 is omitted while the roll cleaning is omitted. Can be raised from T1 to T2 to produce the product film 16 (step S4).

Further, as shown in FIG. 5B, the cast roll 14 and / or the touch roll 15 may be cleaned before the inspection as in the first embodiment (step S0). As described above, since the presence or absence of foreign matter 18 is detected in the inspection after step S2, this cleaning is simpler than the conventional cleaning that does not include the inspection performed before manufacturing the product film 16. It's done.

According to the third embodiment, by determining whether the dent defect 13a is a periodic defect, unnecessary cleaning of the cast roll 14 and / or the touch roll 15 can be avoided, thereby increasing productivity. It is possible to improve.

In the third embodiment, in order to detect the foreign matter 18 adhering to the cast roll 14 and / or the touch roll 15, a dent defect that is concave when the sample 13 is viewed from the surface side in contact with the cast roll 14 is detected. However, it is possible to detect foreign matter adhering to the touch roll 15. In that case, the dent defect which becomes concave when the sample 13 is viewed from the surface side in contact with the touch roll 15 may be detected.

It goes without saying that the method for producing a film is not limited to the first to third embodiments, and may include other steps. For example, in the production of a product film, if necessary, knurling is performed on the edge of the film, a protective film is bonded, both ends of the film are slit and cut to a desired product width, or the film is stretched. May include that.

The thickness of the product film 16 is not particularly limited. As a general tendency, the thinner the product film 16 is, the greater the adverse effect of the dent defect on the characteristics of various films such as optical characteristics. However, according to the present invention, even in an extremely thin product film 16 having a thickness of 30 μm or more and less than 80 μm, preferably 35 μm or more and 70 μm or less, more preferably 40 μm or more and 60 μm or less, the occurrence of dent defects 16a can be remarkably suppressed. The significance of applying the present invention to such a thin film is extremely great.

The extruder 10 used in the film manufacturing method according to the first to third embodiments is a single-screw extruder, a co-directional meshing twin-screw extruder, and a co-directional non-meshing twin-screw extruder. , Different-direction meshing twin-screw extruders, different-direction non-meshing twin-screw extruders, multi-screw extruders and the like can be used. Among them, the single-screw extruder is preferable because it has a small amount of resin retention in the extruder, so that it is easy to suppress thermal deterioration of the thermoplastic resin composition during extrusion, and the equipment cost is low. Further, it is preferable to use an extruder having a venting mechanism in order to remove residual volatile matter in the thermoplastic resin composition and heating products in the extruder 10. The size (caliber) of the extruder 10 is selected according to a desired discharge amount.

As the screw used in the single-screw extruder, a screw having a general full-flight configuration with a compression ratio of about 2 to 3 for an extruder without or with a vent can be used, but it is special so that unmelted material does not remain. A good kneading mechanism (mixing element) may be provided.

The residence time of the thermoplastic resin composition in the extruder 10 is preferably 10 minutes or less, more preferably 5 minutes or less, and particularly preferably 2 from the viewpoint of preventing resin thermal deterioration due to an increase in the residence time. Within minutes.
The residence time depends on the type of extruder 1 and extrusion conditions, but can be shortened by adjusting the material supply amount, L / D, screw rotation speed, screw groove depth, etc. is there.

The molten thermoplastic resin composition obtained by a melting means such as an extruder 10 is then supplied to the die 11. The molten thermoplastic resin composition is preferably supplied using a gear pump (not shown). By using the gear pump, fluctuations in the discharge amount in the extruder 10 are absorbed, the quantitativeness of the supply is remarkably improved, and it is effective in improving the stability of the film thickness over time.

The molten thermoplastic resin composition quantitatively supplied from the gear pump or the molten thermoplastic resin directly supplied from the extruder 10 is supplied to the die 11 through, for example, a tubular flow path, and is supplied from the die outlet 12 to the film. It is discharged in a shape. It is preferable to provide a foreign matter removing device in the flow path from the gear pump to the die 11 or in the flow path from the melting means to the die when the gear pump or the like is not used. As a result, foreign matter contained in the thermoplastic resin composition as a raw material and foreign matter generated by the extruder 10 or the gear pump are trapped, and it is easy to reduce the occurrence of foreign matter defects in the product film 16. As the foreign matter removing device, a screen mesh, a pleated filter, a leaf disc filter, or the like can be used.

As the die 11, various structures can be used. As the die 11, a T die is preferable, and for example, a general coat hanger die can be used. It is more preferable that the die 11 can adjust the gap of an arbitrary portion in the width direction of the lip by pushing a bolt or the like as a thickness adjusting mechanism in the width direction.
In addition, the thickness of the film can be measured online and the portion of the film that deviates from any thickness profile can be automatically adjusted, for example, the thickness profile can be adjusted automatically using a heat-actuated bolt. It is preferable because the change over time can be performed accurately without human intervention.

The residence time of the molten thermoplastic resin composition from the extruder 10 to the ejection from the die 11 is preferably 15 minutes or less, more preferably 10 minutes or less. From the viewpoint of suppressing thermal deterioration of the thermoplastic resin composition, the shorter the residence time of the molten thermoplastic resin composition is, the better.
When removing foreign substances in the molten thermoplastic resin composition using a leaf disc filter, it is the leaf disc filter that requires the longest residence time from the extruder 10 to the discharge from the die 11. Therefore, in order to achieve the above-mentioned residence time, it is preferable to give priority to the filter size design according to the desired production amount as described above.

Further, in cleaning the cast roll 14 and / or the touch roll 15, a conventionally known roll cleaner can be used. By using a roll cleaner, the foreign matter 18 can be efficiently removed in-line. The roll cleaner may be a contact type or a non-contact type, and is preferably a contact type.
When a non-contact roll cleaner that blows compressed gas (for example, air or carbon dioxide) is used, the foreign matter 18 that adheres to the surface of the cast roll 14 and / or the touch roll 15 is removed and then blown off. The 18 may reattach to the surface of the cast roll 14 and / or the touch roll 15.
On the other hand, when a contact-type roll cleaner is used, foreign matter 18 is unlikely to reattach during roll cleaning.
The contact-type roll cleaner may be a long cleaner that contacts the entire width of the roll, or a short cleaner that can contact only a part of the roll and is provided so that it can move freely in the width direction of the roll. There may be. It may be small enough to use a commercially available and inexpensive member, and reciprocate in the width direction of the roll. The roll cleaner is usually provided so as to be in contact with the surface of the cast roll 14 and / or the touch roll 15. Examples of the cleaner member include brushes, cloths (wet / dry type), blades, adhesive rolls, and the like.

As an example of the roll cleaner, a roll cleaner 17 including a cloth 17a and a support 17b that supports the cloth 17a and presses it against the cast roll 14 as shown in FIG. 1 is preferably mentioned. The cloth 17a is a fabric having a function of scraping the foreign matter 18 on the cast roll 14 and holding the scraped foreign matter 18. The roll cleaner 17 is a pressing means (not shown) that presses the support 17b toward the cast roll 14, is freely movable in the roll width direction, and is in contact with the roll surface and away from the roll surface. May be provided with a moving means (not shown) for supporting the support 17b so that the support 17b can be freely moved.

The roll cleaner 17 is preferably a wet type using a cleaning liquid from the viewpoint of easily suppressing dust generation. Specifically, it is preferable that the roll cleaner 17 further includes a cleaning liquid supply means (not shown) for supplying the cleaning liquid to the cloth 17a.
In the roll cleaner 17 provided with the cloth 17a, it is preferable that the contact surface made of the cloth 17a is intermittently or continuously updated at the portion of the roll cleaner 17 in contact with the cast roll 14 and / or the touch roll 15. The cloth 17a is preferably in the form of a long cloth wound, and the roll pressing surface of the long cloth 17a may be intermittently or continuously updated by the feeding portion and the winding portion.

As for the material of the cloth 17a, since the surface temperature of the cast roll 14 and / or the touch roll 15 is usually as high as about 100 ° C., it is preferable that the cloth 17a has heat resistance and solvent resistance, for example, polyester fiber. Examples include cloth.
The support 17b is appropriately designed according to the shape of the cast roll 14 and / or the touch roll 15. As the material of the support 17b, polytetrafluoroethylene (PTFE) or the like is preferably mentioned because it is excellent in heat resistance, solvent resistance and abrasion resistance.

Examples of the pressing method include hydraulic pressure, pneumatic pressure, and mechanical pressing. When the roll cleaner 17 is pressed into contact with the cast roll 14 and / or the touch roll 15, it is preferable that the pressure is uniform in the roll width direction. The pressing pressure against the cast roll 14 and / or the touch roll 15 depends on the shape of the support 17b, but is preferably 1 kg / cm ² or more and 10 kg / cm ² or less, and more preferably 3 kg / cm ² or more and 7 kg / cm. It is ² . By pressing in the above range, the foreign matter 18 can be easily removed without damaging the surface of the cast roll 14 and / or the touch roll 15.

The installation position of the roll cleaner 17 is not particularly limited. The one closer to the die 11 is preferable in terms of removing foreign matter 18, but it may be appropriately installed in consideration of the heat resistance of the roll cleaner 17.

<< Thermoplastic resin composition >>
Hereinafter, the thermoplastic resin composition which is the material of the film will be described.
The thermoplastic resin composition is not particularly limited as long as it can be molded by melt extrusion. Hereinafter, the components contained in the thermoplastic resin composition will be described.

(Thermoplastic resin)
Examples of the thermoplastic resin which is the main component of the thermoplastic resin composition include a polycarbonate resin, an aromatic vinyl resin and its hydrogen additive, a polyolefin resin, an acrylic resin, a polyester resin, a polyarylate resin, and a polyimide resin. , Polyether sulfone resin, polyamide resin, cellulose resin, polyphenylene oxide resin and the like. Of these, acrylic resins are particularly preferable from the viewpoint of transparency.

The acrylic resin is not particularly limited, but a methacrylic resin containing methyl methacrylate as a monomer component can be used. The content of the structural unit derived from methyl methacrylate in the acrylic resin is preferably 30 to 100% by weight, more preferably 50 to 100% by weight, and 80 to 100% by weight from the viewpoint of obtaining good heat resistance and transparency. % Is particularly preferable.
Among the acrylic resins, heat-resistant acrylic resins are preferable.

As a heat-resistant acrylic resin, for example,
1) Acrylic resin in which an N-substituted maleimide compound is copolymerized as a copolymerization component.
2) Acrylic glutarate anhydride,
3) Acrylic resin having a lactone ring structure,
4) Glutarimide acrylic resin,
5) Acrylic resin containing hydroxyl groups and / or carboxyl groups,
6) An aromatic vinyl-containing acrylic polymer obtained by polymerizing an aromatic vinyl monomer and another monomer copolymerizable therewith (for example, a styrene monomer and another single amount copolymerizable therewith). Styrene-containing acrylic polymer obtained by polymerizing the body)
7) A hydrogenated aromatic vinyl-containing acrylic polymer obtained by partially or wholly hydrogenating the aromatic ring of the resin of 6) above (for example, a styrene monomer and another single amount copolymerizable therewith). Partially hydrogenated styrene-containing acrylic polymer obtained by partially hydrogenating the aromatic ring of the styrene-containing acrylic polymer obtained by polymerizing the body),
8) Acrylic polymer containing a cyclic acid anhydride repeating unit and the like can be mentioned.
A glutarimide acrylic resin can be more preferably used from the viewpoint of heat resistance and optical properties.

(Rubber elastic particles)
Further, the thermoplastic resin composition may contain rubber elastic particles for the purpose of imparting strength, toughness and the like.
The resin constituting the rubber elastic particles is not particularly limited, and examples thereof include polymers having a glass transition temperature of less than 20 ° C. Specific examples thereof include butadiene-based crosslinked polymers and (meth) acrylic-based polymers. Examples thereof include rubber-like polymers such as crosslinked polymers and organosiloxane-based crosslinked polymers. Among them, a (meth) acrylic crosslinked polymer (hereinafter, may be simply referred to as “acrylic rubber-like polymer”) is particularly preferable in terms of weather resistance and transparency of the film.

Examples of the acrylic rubber-like polymer include ABS resin rubber and ASA resin rubber. From the viewpoint of transparency and the like, an acrylic graft copolymer containing the acrylic acid ester-based rubber-like polymer shown below (hereinafter referred to as “Acrylic graft copolymer”). , Simply referred to as "acrylic graft copolymer") can be preferably used. The acrylic graft copolymer can be obtained by polymerizing at least one stage or more of a monomer mixture containing a methacrylic acid ester as a main component in the presence of an acrylic acid ester-based rubber-like polymer.

The acrylic acid ester-based rubber-like polymer is a rubber-like polymer containing acrylic acid ester as a main component, and specifically, acrylic acid ester 50% by weight or more and 100% by weight or less, and other copolymerizable vinyls. Monomer mixture consisting of 0% by weight or more and 50% by weight or less of the system monomer (100% by weight) and a polyfunctional monomer having two or more non-conjugated reactive double bonds per molecule 0. It is preferably obtained by polymerizing 05 parts by weight or more and 10 parts by weight or less (relative to 100 parts by weight of the monomer mixture). All the monomers may be mixed and used, or the monomer composition may be changed and used in two or more stages.

As the acrylic acid ester, it is preferable to use an alkyl group having 1 to 12 carbon atoms from the viewpoint of polymerizable property and cost. For example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-butyl acrylate, isobutyl acrylate, benzyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, etc. These monomers may be used in combination of two or more.

As other copolymerizable vinyl-based monomers, (meth) acrylic acid esters are particularly preferable from the viewpoint of weather resistance and transparency, and for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n methacrylic acid. -Butyl, 2-butyl methacrylate, isobutyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, phenoxyethyl (meth) acrylate, phenyl (meth) acrylate and the like can be mentioned. In addition, aromatic vinyls and derivatives thereof, and vinyl cyanide are also preferable, and examples thereof include styrene, methylstyrene, acrylonitrile, and methacrylonitrile. Other examples include unsubstituted and / or substituted maleic anhydrides, (meth) acrylamides, vinyl esters, vinylidene halides, (meth) acrylic acids and salts thereof, and (hydroxyalkyl) acrylic acid esters.

The polyfunctional monomer may be a commonly used one, for example, allyl methacrylate, allyl acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl malate, divinyl adipate, divinylbenzene, ethylene glycol dimethacrylate. , Diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylrol propantrimethacrylate, tetromethylol methanetetramethacrylate, dipropylene glycol dimethacrylate and acrylates thereof and the like can be used. Two or more of these polyfunctional monomers may be used.

Examples of the monomer used for polymerization of a monomer mixture containing a methacrylic acid ester as a main component on an acrylic acid ester-based rubber-like polymer, that is, graft copolymerization, include the above-mentioned methacrylic acid ester and acrylic acid ester. A vinyl-based monomer copolymerizable with the above can be used in the same manner, and a methacrylic acid ester and an acrylic acid ester are preferably used. Methyl methacrylate is preferable from the viewpoint of compatibility with an acrylic resin, and methyl acrylate, ethyl acrylate, and n-butyl acrylate are preferable from the viewpoint of suppressing zipper depolymerization.

The acrylic graft copolymer can be produced by a general emulsion polymerization method. Specifically, a method of continuously polymerizing an acrylic acid ester monomer using an emulsifier in the presence of a water-soluble polymerization initiator can be exemplified.

In the emulsion polymerization method, a usual polymerization initiator can be used. For example, inorganic peroxides such as potassium persulfate and sodium persulfate, organic peroxides such as cumenehydroperoxide and benzoyl peroxide, and oil-soluble initiators such as azobisisobutyronitrile are also used. These may be used alone or in combination of two or more. These initiators are used as ordinary redox-type polymerization initiators in combination with reducing agents such as sodium sulfite, sodium thiosulfate, sodium formaldehyde, sulfoxylate, ascorbic acid, ferrous sulfate and ethylenediaminetetraacetic acid disodium complex. You may use it.

A chain transfer agent may be used in combination with the polymerization initiator. Examples of the chain transfer agent include alkyl mercaptans having 2 to 20 carbon atoms, mercapto acids, thiophenols, carbon tetrachloride and the like, and these may be used alone or in combination of two or more.

The emulsifier used in the emulsion polymerization method is not particularly limited, and any ordinary emulsifier for emulsion polymerization can be used. For example, sulfate ester-based surfactants such as sodium alkylsulfate, sulfonate-based surfactants such as sodium alkylbenzene sulphonate, sodium alkylsulfonate, sodium dioctyl sulfosuccinate, sodium alkylphosphates, polyoxyethylene alkyl ethers. Examples thereof include anionic surfactants such as phosphate-based surfactants such as sodium phosphate ester. Further, the sodium salt may be another alkali metal salt such as potassium salt or an ammonium salt. These emulsifiers may be used alone or in combination of two or more. Further, a nonionic surfactant represented by an alkyl-substituted product or an aryl-substituted product of the polyoxyalkylenes or the terminal hydroxyl group thereof may be used or partially used in combination. Among them, a sulfonate-based surfactant or a phosphate-based surfactant is preferable from the viewpoint of polymerization reaction stability and particle-based controllability, and among them, dioctyl sulfosuccinate or polyoxyethylene alkyl ether phosphoric acid. Ester salts can be used more preferably.

(Other ingredients)
An antioxidant, an ultraviolet absorber, an ultraviolet stabilizer, or the like for improving stability against heat or light may be added to the thermoplastic resin composition alone or in combination of two or more.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

[Example 1]
As the thermoplastic resin composition, an acrylic resin composition having a Tg of 120 ° C. was used. As a film manufacturing apparatus, an apparatus in which a φ90 mm vent type single-screw extruder, a gear pump, a polymer filter, a T-die, and a touch roll and a cast roll in parallel were arranged in order from the upstream side was used.

The method for producing the acrylic resin composition is as follows.
<Production Example 1: Preparation of rubber elastic particles (acrylic graft copolymer)>
The following substances were charged into an 8 L polymerization apparatus equipped with a stirrer.
Deionized water 180 parts by weight Polyoxyethylene lauryl ether phosphoric acid (embroidery) 0.031 parts by weight borate 0.4725 parts by weight sodium carbonate 0.04725 parts by weight sodium hydroxide 0.0098 parts by weight Nitrogen gas is sufficient in the polymerization machine. The internal temperature was adjusted to 80 ° C., and 0.027 parts by weight of potassium persulfate as a polymerization initiator was added in the form of a 2% by weight aqueous solution. Next, 27 parts by weight of the monomer mixture (93.2% by weight of methyl methacrylate, 6% by weight of butyl acrylate, 0.8% by weight of styrene), 0.135 parts by weight of allyl methacrylate, which is a polyfunctional monomer. , 0.3 part by weight of n-octyl mercaptan as a chain transfer agent and 0.0934 part by weight of polyoxyethylene lauryl ether phosphoric acid as an emulsifier were continuously added over 81 minutes. The polymer (I) was obtained by continuing the polymerization for another 60 minutes.

Then, 0.0267 parts by weight of sodium hydroxide was added to the polymer (I) in the form of a 2% by weight aqueous solution, and 0.08 parts by weight of potassium persulfate was added in the form of a 2% by weight aqueous solution. Then, a monomer mixture (82% by weight of butyl acrylate, 18% by weight of styrene), 0.75 parts by weight of allyl methacrylate, and 0.2328 parts by weight of polyoxyethylene lauryl ether phosphoric acid were continuously added over 150 minutes. did. After completion of the addition, 0.015 parts by weight of potassium persulfate as an initiator was added in the form of a 2% aqueous solution, and the polymerization was continued for 120 minutes to obtain a polymer (II).

Then, 0.023 parts by weight of potassium persulfate was added to the polymer (II) in the form of a 2% by weight aqueous solution. Then, 15 parts by weight of the monomer mixture (95% by weight of methyl methacrylate, 5% by weight of butyl acrylate) was continuously added over 45 minutes, and the polymerization was continued for another 30 minutes.
Next, 8 parts by weight of the monomer mixture (52% by weight of methyl methacrylate, 48% by weight of butyl acrylate) was continuously added over 25 minutes, and the polymerization was continued for another 60 minutes to carry out the copolymerization of the multistage polymerization graft. A coalesced latex was obtained.
The obtained latex was salted out with magnesium sulfate, coagulated, washed with water, and dried to obtain a white powdery multistage acrylic graft polymer. The average particle size of the obtained rubber elastic particles (acrylic graft copolymer) was 221 nm.

<Production Example 2: Preparation of acrylic resin composition>
The rubber elastic particles (acrylic graft copolymer) obtained in Production Example 1 and the acrylic resin (Mw: 105,000) having 100% polymethylmethacrylate structural units have a weight ratio of 15:85. And mixed. Subsequently, this mixture was melt-extruded with a φ58 mm vent type twin-screw extruder, and the resin that came out as a strand from the die provided at the outlet of the extruder was cooled in a water tank and pelletized with a pelletizer. A resin composition was obtained.

First, as an inspection, the acrylic resin composition is put into an extruder to be melted, and the temperature T1 of the film-like melt of the acrylic resin composition extruded from the T die is 255 ° C. as the temperature at the outlet of the T die. Melt extrusion was performed under certain conditions. Then, the film-like melt was sandwiched between a touch roll and a cast roll whose temperature was adjusted to 95 ° C., and formed into a film having a film thickness of 80 μm.

Next, a dent defect of this film was visually detected. The opening width X1 of the dent defect was as large as about 200 μm, and the dent defect could be easily and quickly detected visually.

Based on the position information of the defect occurrence location, the location requiring cleaning (position in the roll width direction) was determined, and the cast roll was cleaned with a roll cleaner.
The roll cleaner can move freely in the roll width direction with a cloth (wet type) that comes into contact with the cast roll and removes foreign matter by wiping, a support that supports the cloth, and a pressing means that presses the support toward the roll. Therefore, it is composed of a moving means for supporting the support so that it can move freely in a direction in contact with the roll surface and a direction away from the roll surface. With this roll cleaner, the desired position of the roll can be cleaned.

Next, as a product film production, the acrylic resin composition was put into an extruder to be melted, and melt extrusion was performed under the condition that the temperature T2 of the acrylic resin composition melt-extruded from the T-die outlet was 275 ° C. Then, the film-like acrylic resin composition in a molten state was sandwiched between a touch roll and a cast roll whose temperature was adjusted to 95 ° C. to obtain a product film having a thickness of 80 μm.
When the defect generation evaluation of the film acquired in the production of the product film was performed, the number of dent defects generated was 0 / m ² .
The number of dented defects generated in the product film was evaluated by visually detecting the defects in the acquired product film under a light source with a luminous intensity of 1000 lux, and using a digital microscope to detect the detected defects when the opening width X1 was 100 μm or more. The number of certain dent defects was calculated.

[Comparative Example 1]
The product film was obtained in the same manner as in Example 1 except that the inspection was not performed.
When the defect generation evaluation of the product film acquired in the product film production was performed, the number of dent defects having an opening width X2 of 100 μm or more was 20 / m ² . The method of calculating the dent defect is the same as that of the first embodiment.

[Comparative Example 2]
In the inspection, a film having a thickness of 80 μm was formed by the same method as in Example 1 except that melt extrusion was performed under the condition that the resin temperature T1 was 275 ° C. Next, the concave defect of this film was visually detected. Based on the detection result of this defect, the part requiring cleaning was determined, and the roll was cleaned with a roll cleaner.
When the defect generation evaluation of the product film acquired in the product film manufacturing was performed, the number of dent defects generated was 9 pieces / m ² . The method of calculating the dent defect is the same as that of the first embodiment.

According to the first embodiment, the temperature T1 at the die outlet of the film-like melt in the inspection is lower than the temperature T2 at the die outlet of the film-like melt in the product film production, so that the defect is accurate in the inspection. It was able to be detected well and quickly. As a result, it can be seen that the foreign matter on the roll can be reliably removed, and that no dent defect occurs in the production of the product film.
On the other hand, according to Comparative Example 1, since the inspection was not performed, it can be seen that the foreign matter on the roll could not be completely removed, and many dent defects were generated due to this foreign matter.
Further, according to Comparative Example 2, it can be seen that a defect caused by a foreign substance that could not be completely removed was generated although the inspection was performed. This is because, in the inspection, the temperature of the acrylic resin composition is the same as that at the time of producing the product film (temperature T1 = temperature T2), so that the opening width X1 of the dent defect is 100 μm, which is smaller than that of Example 1, and is on the film. This is probably because the dent defect was overlooked.

10 Extruder 11 Die 12 Die outlet 13'Film-like melt 13 Specimen 14 Cast roll 15 Touch roll 16' Film-like melt 16 Product film 17 Roll cleaner 18 Foreign matter

Claims (8)

A method for producing a film made of a thermoplastic resin composition.
An inspection including extruding the molten thermoplastic resin composition from a die as a film-like melt, sandwiching it with a pair of rolls to form a film-like sample, and then detecting defects on the surface of the sample. ,
A product film production by extruding the molten thermoplastic resin composition from the die as the film-like melt and then sandwiching it with a pair of rolls to form a film.
The inspection is performed before the production of the product film.
When the defect is detected, the surface of the roll is cleaned before the production of the product film.
In the inspection, the temperature T1 of the thermoplastic resin composition extruded from the die is 10 ° C. or more lower than the temperature T2 of the thermoplastic resin composition extruded from the die in the product film production.
How to make a film. A method for producing a film made of a thermoplastic resin composition.
An inspection including extruding the molten thermoplastic resin composition from a die as a film-like melt, sandwiching it with a pair of rolls to form a film-like sample, and then detecting defects on the surface of the sample. ,
A product film production is provided in which the molten thermoplastic resin composition is extruded from the die as the film-like melt, and then the film-like melt is sandwiched between a pair of rolls and molded into a film.
The inspection is performed before the production of the product film.
When the defect is detected in the inspection and the defect is a periodic defect generated corresponding to the rotation cycle of the roll, the surface of the roll is cleaned before the production of the product film. Made,
In the inspection, the temperature T1 of the thermoplastic resin composition extruded from the die is 10 ° C. or more lower than the temperature T2 of the thermoplastic resin composition extruded from the die in the product film production.
How to make a film. When the glass transition temperature of the thermoplastic resin composition is Tg, the Tg, the T1 and the T2 are described in 1) and 2):
1) Tg <T1 <Tg + 140 ° C,
2) T2 ≧ Tg + 140 ° C
The method for producing a film according to claim 1 or 2 , which satisfies the above relationship. In the test, the surface where the defect occurred in the sample was identified.
The method for producing a film according to any one of claims 1 to 3 , wherein the surface of the roll in contact with the surface on which the defect has occurred is cleaned from the pair of rolls. The method for producing a film according to any one of claims 1 to 4 , wherein the surface of the roll is cleaned by a roll cleaner provided in contact with the surface of the roll or in the vicinity of the surface of the roll. The roll cleaner is provided so as to be in contact with the surface of the roll.
The method for producing a film according to claim 5 , wherein a cloth is arranged at a portion of the roll cleaner in contact with the roll. The method for producing a film according to claim 6 , wherein the cleaning is performed by supplying a cleaning liquid to the cloth and performing the cleaning in a wet manner. The method for producing a film according to any one of claims 1 to 7 , wherein the thermoplastic resin composition is an acrylic resin composition.

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