JP7840182B2 - Film manufacturing method - Google Patents

Description

This disclosure relates to a method for manufacturing a film and an apparatus for manufacturing a film.

Patent documents 1 to 5 disclose a method for manufacturing a film that includes a step of stretching the raw material.

Japanese Patent Publication No. 2002-361733 Japanese Patent Publication No. 2008-188792 Japanese Patent Publication No. 2009-132123 Japanese Patent Publication No. 2013-001072 Japanese Patent Publication No. 2013-203055

When the raw material is stretched in the transport direction, it tends to shrink in the width direction. This shrinkage causes wrinkles in the film.

To solve the above problems, a method for manufacturing a film according to one aspect of this disclosure includes (1) a step of heating a conveyed roll of raw material by radiation from a heater and stretching it in the conveying direction, wherein in step (1), each of the ends of the roll of raw material is covered with a shielding material that blocks radiation from the heater.

In one aspect of this disclosure, the method for manufacturing a film may involve a far-infrared heater.

A method for manufacturing a film according to one aspect of this disclosure may involve inserting the shielding material between the heater and each of the ends of the raw material in step (1).

A method for manufacturing a film according to one aspect of this disclosure may involve using a reflector provided on the opposite side of the heater from the raw material in step (1).

A method for manufacturing a film according to one aspect of this disclosure may involve inserting the shielding material between the reflector and each of the ends of the raw material in step (1).

A method for manufacturing a film according to one aspect of this disclosure may involve a method in which the shielding material includes at least one selected from the group including stainless steel and steel.

A method for manufacturing a film according to one aspect of this disclosure may be a method in which the width of the shielding covering each of the two ends is 3 mm or more and less than 30 mm.

A method for manufacturing a film according to one aspect of this disclosure may be one in which the shielding material has a portion that does not overlap with the raw material in a plan view.

A method for manufacturing a film according to one aspect of this disclosure may involve a method in which the raw material includes at least one selected from the group consisting of polyimide, polyethylene terephthalate, polyethylene naphthalate, polypropylene, and polyester.

In one aspect of the present disclosure, the method for manufacturing a film may be a method in which the stretching method in step (1) is uniaxial stretching using a driven roll.

A method for manufacturing a film according to one aspect of this disclosure may involve not covering the central portion between the two ends of the raw material with the shielding material in step (1).

A method for manufacturing a film according to one aspect of this disclosure may be a method for manufacturing a long film by continuously performing step (1) described above.

A method for manufacturing a film according to one aspect of this disclosure may be a method in which (2) the step of removing both ends of the raw material is performed on the raw material after step (1).

A method for manufacturing a film according to one aspect of this disclosure may involve using a blade to separate both ends from the raw material in step (2).

A method for manufacturing a film according to one aspect of this disclosure may be a method in which the film is a transparent polyimide film having a total light transmittance of 80% or more per 50 μm thickness.

A method for manufacturing a film according to one aspect of this disclosure may be a method in which the film is a thermoplastic film.

A film manufacturing apparatus according to one aspect of this disclosure comprises a heater for heating a conveyed roll of raw material by radiation, a shielding material that covers each of the ends of the roll of raw material and shields it from radiation from the heater, and a stretching unit that stretches the roll of raw material in the conveying direction.

According to one aspect of this disclosure, a method and apparatus for manufacturing a film in which a raw material is stretched while reducing the occurrence of wrinkles can be realized.

This is a schematic diagram showing an example of the general configuration of a film manufacturing apparatus according to one embodiment of the present disclosure. This is a cross-sectional view of the portion of the schematic configuration shown in Figure 1 where the raw material is heated and stretched. This is a perspective view showing the portion of the schematic configuration shown in Figure 1 where both ends are cut off from the raw material. This is a plan view showing the raw material S before stretching in the comparative example. This is a plan view showing the stretched raw material S in the comparative example. This is a plan view showing the stretched raw material in one embodiment of the present disclosure. This is a schematic diagram showing an example of the schematic configuration of a film manufacturing apparatus according to another embodiment of the present disclosure. This is a cross-sectional view of the portion of the schematic configuration shown in Figure 7 where the raw material is heated and stretched.

[Embodiment 1]
(Manufacturing method)
Hereinafter, a method for manufacturing a thermoplastic film F according to one embodiment of this disclosure will be described with reference to Figures 1 to 3.

Figure 1 is a schematic diagram showing an example of the general configuration of the film manufacturing apparatus 2 according to this embodiment. Figure 1 is a view from a direction perpendicular to a plane parallel to the length direction of the raw material roll S and perpendicular to the width direction of the raw material roll S. The upstream side of the raw material roll S conveyance is shown on the left, and the downstream side is shown on the right. In Figure 1, the conveyance direction is the length direction of the raw material roll S.

Figure 2 is a cross-sectional view taken along the AB arrow, showing the portion of the schematic configuration shown in Figure 1 where the raw material S is heated and stretched. Figure 3 is a perspective view showing the portion of the schematic configuration shown in Figure 1 where both ends 14 and 16 are cut off from the raw material S. In Figure 3, the upstream side of the raw material S transport is shown towards the back, and the downstream side is shown towards the front.

First, the raw material S is transported through the conveyor roll R1 to the drive roll R2. The drive roll R2 then rotates, gripping the raw material S between itself and the nip roll N1, driving its transport. Next, the raw material S is transported to another drive roll R3. The drive roll R3 then rotates, gripping the raw material S between itself and the nip roll N2, driving its transport. The transport speed by the downstream drive roll R3 is greater than that by the upstream drive roll R2. This speed difference applies tension in the transport direction to the raw material S between the drive rolls R2 and R3. Simultaneously, the heater 4 heats the raw material S by radiation between the drive rolls R2 and R3. As a result, the raw material S is uniaxially stretched by the drive rolls R2 and R3, and the direction of this stretching is in the transport direction.

Furthermore, while the raw material S is being heated and stretched, the shields S1 and S2 cover one side of each of the ends 14 and 16 of the raw material S so that the central part 18 of the raw material S is not covered. Specifically, the first shield S1 is inserted between the heater 4 and the first end 14 of the raw material S, and the second shield S2 is inserted between the heater 4 and the second end 16 of the raw material S. This reduces the heating of both ends 14 and 16 of the raw material S by the heater 4. The first end 14 is one end in the width direction of the raw material S, and the second end 16 is the other end in the width direction of the raw material S. The width direction of the raw material S intersects or is approximately perpendicular to the conveying direction.

The heater 4 may be a far-infrared heater. The heater 4 heats the raw material S such that the surface temperature of the central part 18 of the raw material S is within the range from near the glass transition temperature to near the softening temperature of the raw material S. The central part 18 of the raw material S is located between the ends 14 and 16 of the raw material S. Under heating, the surface temperature of the central part 18 of the raw material S may be within the range from 30 degrees Celsius lower than the glass transition temperature of the raw material S to 20 degrees Celsius higher than the softening temperature of the raw material S. Preferably, the surface temperature under heating is within the range from 20 degrees Celsius lower than the glass transition temperature of the raw material S to the softening temperature of the raw material S. Furthermore, a reflector 6 may be provided on the opposite side of the heater 4 from the raw material S. The reflector 6 reflects the heat or heat rays radiated from the heater 4 towards the raw material S.

Here, the glass transition temperature (Tg) is defined as the temperature at the inflection point obtained by plotting the correlation between the storage modulus of the raw material S and the measured temperature, after measuring the dynamic viscoelasticity of the raw material S. The dynamic viscoelasticity of the raw material S is measured using a DMS-200 manufactured by Seiko Electronics Industries, Ltd., with a measurement jig spacing of 20 mm and a frequency of 5 Hz. Furthermore, the temperature at which the storage modulus at the inflection point is 1/1000 of the storage modulus is defined as the softening temperature (Tm).

Next, the raw material S is conveyed to the conveyor roll R4 while dissipating heat. Then, on the conveyor roll R4, or between the conveyor roll R4 and the next conveyor roll R5, both ends 14 and 16 are removed from the raw material S to obtain a thermoplastic film F. For example, a blade 8 is provided on the conveyor roll R4, or between the conveyor roll R4 and the next conveyor roll R5, and the blade 8 is used to separate both ends 14 and 16 from the raw material S.

Next, the thermoplastic film F is further conveyed via the conveyor roll R5. Meanwhile, the removed ends 14 and 16 are collected in the recovery unit 12. For example, the recovery unit 12 may include a winding device for winding the first end 14 and a winding device for winding the second end 16.

By continuously performing the above process, a long thermoplastic film F can be manufactured.

(manufacturing equipment)
As shown in Figures 1 to 3, the film manufacturing apparatus 2 according to this embodiment is a thermoplastic film F manufacturing apparatus and comprises a heater 4 for heating the raw material S being conveyed, shielding objects S1 and S2 that cover the heater 4-side surfaces of both ends 14 and 16 of the raw material S and shield from radiation from the heater 4, and drive rolls R2 and R3 and nip rolls N1 and N2 (stretching section) for stretching the raw material S in the conveying direction. The film manufacturing apparatus 2 may further include a blade 8 (removal section) for removing both ends 14 and 16, conveying rolls R1, R4 and R5, and a recovery section 12.

(Shielding and raw materials)
The shielding objects S1 and S2 and the raw material S will be explained below, with further reference to Figure 2.

The shields S1 and S2 shield against radiation from the heater 4. The shields S1 and S2 may either reflect or absorb the radiated electromagnetic waves. If absorption occurs, it is preferable that the shields S1 and S2 are connected to or have a heat dissipation section. The shields S1 and S2 may include, for example, at least one selected from the group including stainless steel (SUS) and steel. For example, structural rolled steel (SS) can be used as the steel. It is preferable that the shields S1 and S2 are the same, but they may be different.

The width W3 that the shielding objects S1 and S2 cover each of the ends 14 and 16 of the raw material S is selected so that both ends 14 and 16 of the raw material S can be stretched together with the central part 18 of the raw material S, while the ends 14 and 16 of the raw material S are not softened by heating. This covering width W3 is the width of the portion 22 of each of the shielding objects S1 and S2 that overlaps with the raw material S in a plan view. For this reason, when the width W2 of the raw material S is 300 mm and the distance D1 from the shielding objects S1 and S2 to the raw material S is 5 mm, the covering width W3 is preferably 3 mm or more and less than 30 mm. That is, the ratio of the covering width W3 to the width W2 of the raw material S (W3/W2) is preferably 1% or more and 10% or less. The distance D1 from the shielding object S1 to the raw material S is the distance from the surface of each shielding object S1 and S2 on the side of the raw material S to the corresponding surface of the raw material S on the shielding object S1 and S2 sides. The width W1 of the first shielding object S1 covering the first end 14 and the width W1 of the second shielding object S2 covering the second end 16 are preferably the same, but may be different. Furthermore, the distance D1 from the first shielding object S1 to the raw material S and the distance D1 from the second shielding object S2 to the raw material S are preferably the same, but may be different.

Furthermore, each of the shields S1 and S2 may have a portion 24 that does not overlap with the raw material S in a plan view. This non-overlapping portion 24 protrudes outward from the raw material S in the width direction. This non-overlapping portion 24 can function as a heat dissipation section. The width W4 of the non-overlapping portion 24 of the first shield S1 and the width W4 of the non-overlapping portion 24 of the second shield S2 are preferably the same, but they may be different.

The glass transition temperature of the base material S may be, for example, 60°C to 370°C. The base material S may contain at least one selected from the group including, for example, polyimide, polyethylene terephthalate, polyethylene naphthalate, polypropylene, and polyester. It is preferable that the base material S contains polyimide so that the thermoplastic film F is a transparent polyimide film with a total light transmittance of 80% or more per 50 μm thickness. Here, the total light transmittance should be measured in accordance with JIS standard K7361-1:1997.

By covering one side of both ends 14 and 16 of the raw material S with shields S1 and S2, both ends 14 and 16 are not heated or softened. That is, the rigidity of both ends 14 and 16 of the raw material S is maintained even while the raw material S is heated and stretched. Therefore, by applying a large tension to the raw material S and stretching it, the shrinkage in the width direction of the raw material S caused by stretching can be reduced. In addition, breakage of the raw material S in the transport direction is prevented. Tensile strength is the applied tension when pulled to the breaking limit, and should be measured in accordance with JIS standard K7127:1999.

The comparative examples and embodiments of this disclosure will be described below with reference to Figures 4 to 6.

[Comparative Example 1]
Figure 4 is a plan view showing the raw material S before stretching in Comparative Example 1. Figure 5 is a plan view showing the raw material S after stretching in Comparative Example 1.

In Comparative Example 1, stainless steel plates were used as shielding materials S1 and S2. The width W1 of shielding materials S1 and S2 was 50 mm, the thickness was 5 mm, and the length was 300 mm. The shielding materials S1 and S2 were installed across the drive rolls R2 and R3 such that they did not completely cover the raw material S. That is, the covering width W3 was 0 mm. The raw material S was a colorless, transparent polyimide film with a width W2 of 300 mm, a thickness of 50 μm, a tensile strength per unit width in the longitudinal direction of 17,000 N/m, and a glass transition temperature of 300 degrees Celsius. The width W2 of the raw material S at this time was defined as "width W2b before stretching".

As shown in Figure 4, marks M1 and M2 were placed on the central part 18 of the raw material S, separated along the length of the material S. The distance D2 between marks M1 and M2 was then measured. This measured distance D2 was defined as the "length D2b before stretching."

Next, the raw material S was sandwiched between the drive roll R2 and nip roll N1, and between the drive roll R3 and nip roll N2. At this time, the distance from the raw material S to the heater 4 was 40 mm, and the distance from the raw material S to the reflector 6 was 20 mm. The raw material S was then heated by the heater 4 and reflector 6, and uniaxially stretched by the drive rolls R2, R3 and nip rolls N1, N2. At this time, the conveying speed of the raw material S was 0.4 m/min, and the tension applied to the raw material S in the conveying direction was 188 N/m. The heater 4 was a far-infrared heater, and the surface temperature of the central part 18 of the raw material S reached a temperature range of 300 degrees Celsius to 350 degrees Celsius.

The stretching of the raw material S was completed without any breakage. After the stretching was complete, the raw material S was removed from between the drive roll R2 and the nip roll N1, and from between the drive roll R3 and the nip roll N2.

As shown in Figure 5, the width W2 of the roll S was then measured at the position where its width W2 was smallest, and this measured width W2 was defined as the "stretched width W2a". The distance D2 between marks M1 and M2 was also measured, and this measured distance D2 was defined as the "stretched length D2a". The stretching rate (%) in the transport direction and the shrinkage rate (%) in the width direction of the roll S were then calculated as follows.

Elongation ratio in the transport direction = (D2a - D2b) / D2b * 100%
Shrinkage rate in the width direction = (W2b - W2a) / W2b * 100%
The asterisk (*) is an operator that indicates multiplication.

The stretched portion of the raw material S had wrinkles C1 at both ends 14, 16 and in the central part 18. The wrinkles C1 generally extended diagonally with respect to the stretching direction and the width direction.

[Comparative Example 2]
Comparative Example 2 was carried out in the same manner as Comparative Example 1, except that the shielding objects S1 and S2 were installed so that they covered both ends 14 and 16 of the raw material S with a constant width W3, and the width W3 was 30 mm, across the drive rolls R2 and R3. As a result, the raw material S did not stretch.

[Example 1]
Example 1 was carried out in the same manner as Comparative Example 2, except that the width W3 of the shielding objects S1 and S2 covering both ends 14 and 16 was 5 mm.

Figure 6 is a plan view showing the stretched raw material S in Example 1. As shown in Figure 6, the stretched portion of the raw material S had wrinkles C2 only at both ends 14 and 16, while the central portion 18 was wrinkle-free. The wrinkles C2 generally extended parallel to the stretching direction.

[Example 2]
Example 2 was carried out in the same manner as Comparative Example 2, except that the width W3 of the shielding objects S1 and S2 covering both ends 14 and 16 was 20 mm. As a result, similar to Example 1, wrinkles C2 were present only at both ends 14 and 16.

The stretch ratio in the transport direction and the shrinkage ratio in the width direction of the raw material S, calculated in Comparative Examples 1 and 2 and Examples 1 and 2 described above, are shown in Table 1 below.

As shown in Table 1, in the range where the width W3 of the shielding objects S1 and S2 covering both ends 14 and 16 is greater than 0 mm and less than 30 mm, the stretching rate of the raw material S in the transport direction was greater than 0%, and the shrinking rate of the raw material S in the width direction was 5% or less. Furthermore, in this range, there were no wrinkles in the central part 18 of the stretched portion of the raw material S.

[Embodiment 2]
Other embodiments of this disclosure are described below. For the sake of clarity, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

Figure 7 is a schematic diagram showing an example of the general configuration of the film manufacturing apparatus 2 according to this embodiment. Figure 7 is a view taken from a direction perpendicular to a plane parallel to the length direction of the raw material roll S and perpendicular to the width direction of the raw material roll S, with the upstream side of the raw material roll S conveyance shown on the left and the downstream side on the right. In Figure 8, the conveyance direction is the length direction of the raw material roll S. Figure 8 is a cross-sectional view taken along the AB arrow, showing the portion of the schematic configuration shown in Figure 7 where the raw material roll S is heated and stretched.

As shown in Figures 7 and 8, the method for manufacturing the thermoplastic film F according to this embodiment is equivalent to the method for manufacturing the thermoplastic film F according to Embodiment 1 described above, except that the shielding materials S1 to S4 cover both sides of each of the ends 14 and 16 of the raw material S. Specifically, in the manufacturing method according to this embodiment, a first shielding material S1 is inserted between the heater 4 and the first end 14 of the raw material S, a second shielding material S2 is inserted between the heater 4 and the second end 16 of the raw material S, a third shielding material S3 is inserted between the reflector 6 and the first end 14 of the raw material S, and a fourth shielding material S4 is inserted between the reflector 6 and the second end 16 of the raw material S.

By covering both ends 14 and 16 with shielding materials S1 to S4, heating to both ends 14 and 16 is further reduced, thereby further reducing shrinkage in the width direction of the raw material S caused by stretching.

The film manufacturing apparatus 2 according to this embodiment further includes, in addition to the configuration of the film manufacturing apparatus 2 according to the previously described embodiment 1, shielding objects S1 and S2 that cover the reflector 6 side of each of the two ends 14 and 16 of the raw material S.

This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of this disclosure.

2 Manufacturing equipment 4 Heater 6 Reflector 8 Blade 14, 16 End F Thermoplastic film (film)
N1, N2 Nip rolls R1, R4, R5, R6, R7 Conveyor rolls R2, R3 Drive rolls S Raw material S1, S2, S3, S4 Obstruction material W1, W2, W3, W4 Width

Claims (14)

A method for manufacturing a film,
(1) The process includes heating the conveyed raw material by radiation from a heater and stretching it in the conveying direction,
In step (1) above, each of the ends of the raw material is covered with a shield to block radiation from the heater, while the central part of the raw material between the ends is not covered with the shield, and the surface temperature of the central part of the raw material is heated to a temperature ranging from 30 degrees Celsius lower than the glass transition temperature of the raw material to 20 degrees Celsius higher than the softening temperature of the raw material.
Let W2 be the width of the raw material, and let W3 be the width over which the shielding material covers each of the ends of the raw material in step (1), such that W3/W2 is 1% or more and 10% or less.
A method for producing a film , characterized in that the raw material comprises at least one selected from the group consisting of polyimide, polyethylene terephthalate, polyethylene naphthalate, polypropylene, and polyester . The method for manufacturing a film according to claim 1, characterized in that the heater is a far-infrared heater. The method for manufacturing a film according to claim 2, characterized in that, in step (1), the shielding material is inserted between the heater and each of the ends of the raw material. The method for manufacturing a film according to claim 2 or 3, characterized in that, in step (1), a reflector provided on the opposite side of the raw material from the heater is used. The method for manufacturing a film according to claim 4, characterized in that, in step (1), the shielding material is inserted between the reflector and each of the ends of the raw material. The method for manufacturing a film according to any one of claims 1 to 5, characterized in that the shielding material includes at least one selected from the group including stainless steel and steel materials. The method for manufacturing a film according to any one of claims 1 to 6, characterized in that the width of the shield covering each of the two ends is 3 mm or more and less than 30 mm. The method for manufacturing a film according to any one of claims 1 to 7, characterized in that the shielding material has a portion that does not overlap with the raw material in a plan view. The method for manufacturing a film according to any one of claims 1 to 8 , characterized in that the stretching method in step (1) is uniaxial stretching using a drive roll. A method for manufacturing a film according to any one of claims 1 to 9 , characterized in that the above step (1) is carried out continuously to manufacture a long film. (2) The method for manufacturing a film according to any one of claims 1 to 10 , characterized in that the step of removing both ends of the raw material is performed on the raw material after step (1). The method for manufacturing a film according to claim 11 , characterized in that in step (2) above, the ends of the raw material are cut off using a blade. The method for manufacturing a film according to any one of claims 1 to 12 , characterized in that the film is a transparent polyimide film having a total light transmittance of 80% or more per 50 μm thickness. The method for manufacturing a film according to any one of claims 1 to 13 , characterized in that the film is a thermoplastic film.