stretching apparatus, stretching method, film manufacturing apparatus

Abstract

To suppress occurrence of wrinkles when stretching a film.SOLUTION: A stretching device (101) comprises: a first conveyance roll; a second conveyance roll; a third conveyance roll (23); a fourth conveyance roll (24); a fifth conveyance roll; a sixth conveyance roll; and a main heating unit (120) that performs main heating at a space between the third conveyance roll and the fourth conveyance roll that is provided at a predetermined interval on a downstream side in a conveyance direction of an original roll (S). A holding angle of the original roll (S) by the fourth conveyance roll (24) is 90°±10°.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a stretching device for stretching a film, a stretching method, and a film manufacturing device.

Background Art

[0002] Patent Documents 1 to 8 disclose a stretching device for stretching a film while heating.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there is a problem that wrinkles occur in the film when the film is heated and stretched.

Means for Solving the Problems

[0005] To solve the above problems, a stretching apparatus according to one aspect of the present disclosure is a stretching apparatus that heats and stretches a film made of a thermoplastic resin while conveying it, comprising: a first guide roll that guides the conveyance of the film; a second guide roll positioned downstream of the film in the conveyance direction at a predetermined distance from the first guide roll; and a heating heater that heats the film to stretch it between the first guide roll and the second guide roll, wherein the angle at which the film is gripped by the second guide roll is 90°±10°.

[0006] A stretching apparatus according to one aspect of the present disclosure may also include a preheating heater positioned upstream of the first guide roll in the film transport direction, which heats the film to a temperature lower than that of the heating heater.

[0007] A stretching apparatus according to one aspect of the present disclosure may be an apparatus in which the heating temperature by the preheating heater is 10°C to 50°C lower than the heating temperature by the main heating heater.

[0008] A stretching apparatus according to one aspect of the present disclosure may also include a relaxation heater positioned downstream of the second guide roll in the film transport direction, which heats the film to a temperature lower than that of the heating heater.

[0009] A stretching apparatus according to one aspect of the present disclosure may be an apparatus in which the relaxation temperature by the relaxation heater is 10°C to 50°C lower than the heating temperature by the heating heater.

[0010] A stretching apparatus according to one aspect of the present disclosure may be an apparatus in which the heating heater and the preheating heater are provided on the front and back sides of the film, respectively.

[0011] The stretching apparatus according to one aspect of the present disclosure may be an apparatus in which the heating heater, the preheating heater, and the relaxation heater are far-infrared heaters.

[0012] A stretching apparatus according to one aspect of the present disclosure further comprises: a third guide roll positioned upstream of the first guide roll in the film transport direction and guiding the film toward the first guide roll; and a fourth guide roll positioned downstream of the second guide roll in the film transport direction and guiding the film fed from the second guide roll toward the downstream side in the transport direction, wherein the first guide roll and the third guide roll stretch the film longitudinally, and the second guide roll and the fourth guide roll stretch the film longitudinally.

[0013] The stretching apparatus according to one aspect of this disclosure may be an apparatus in which the diameter of the second guide roll is 150 mm or more.

[0014] A stretching apparatus according to one aspect of the present disclosure may be an apparatus in which the transport speed of the film fed from the second guide roll is set to a speed difference of +0.1% to +10% with respect to the transport speed of the film fed to the first guide roll.

[0015] A stretching method according to one aspect of the present disclosure is a method for stretching a film made of a thermoplastic resin, which involves heating and stretching the film while conveying it, and includes a first step of heating the film with a heating heater between a first guide roll that guides the conveyance of the film and a second guide roll that is positioned at a predetermined distance downstream in the direction of conveyance of the film; and a second step of the second guide roll feeding out the film that has been heated in the first step at an angle of 90°±10°. [Effects of the Invention]

[0016] According to one aspect of this disclosure, a stretching device that reduces the occurrence of wrinkles in a film can be realized. [Brief explanation of the drawing]

[0017] [Figure 1]It is a schematic diagram showing an example of the schematic configuration of a film manufacturing apparatus provided with a stretching device according to an embodiment of the present disclosure. [Figure 2] It is a functional block diagram of the film manufacturing apparatus shown in FIG. 1. [Figure 3] It is an external view of the film stretched using the stretching device shown in FIG. 1. [Figure 4] It is an external view of the stretched film in the comparative example.

Mode for Carrying Out the Invention

[0018] 〔Embodiment 一〕 Hereinafter, an embodiment of the present disclosure will be described in detail. In this embodiment, first, a film manufacturing apparatus provided with the stretching device of the present disclosure will be described.

[0019] (Film manufacturing apparatus) FIG. 1 is a schematic diagram showing an example of the schematic configuration of a film manufacturing apparatus 1 according to the present embodiment. The film manufacturing apparatus 1 manufactures a thermoplastic film 201 by heat-stretching a raw roll S. FIG. 1 is a view seen from a direction orthogonal to a plane parallel to the length direction of the raw roll S and orthogonal to the width direction of the raw roll S, showing the upstream side of the conveyance of the raw roll S on the left side and the downstream side on the right side. In FIG. 1, the conveyance direction is the length direction of the raw roll S.

[0020] The film manufacturing apparatus 1 includes a stretching device 101 that obtains a thermoplastic film 201 by heating and stretching a raw material roll S, a first nip section 31 for feeding the raw material roll S to the stretching device 101, and a second nip section 32 for feeding the thermoplastic film 201 fed from the stretching device 101 to a winding roll (not shown) located downstream. Here, a colorless, transparent polyimide film is used as the raw material roll S for manufacturing the thermoplastic film 201 with the film manufacturing apparatus 1. Note that the raw material roll S is not limited to a polyimide film, but may be any film made of a thermoplastic resin, including at least one selected from the group including polyethylene terephthalate, polyethylene naphthalate, polypropylene, and polyester.

[0021] As shown in Figure 1, the stretching device 101 includes a first conveyor roll 21, a second conveyor roll 22 (third guide roll), a third conveyor roll (first guide roll) 23, a fourth conveyor roll (second guide roll) 24, a fifth conveyor roll (fourth guide roll) 25, and a sixth conveyor roll 26, arranged in order from the upstream side of the conveyance of the raw material S. Each of these conveyor rolls is a rotatable roll to which no driving force is directly transmitted from a drive source (drive motor, etc.). Furthermore, these conveyor rolls are arranged at predetermined intervals from each other.

[0022] The first and second transport rolls 21 and 22 are in contact with the surface Sa of the raw material S, the third and fourth transport rolls 23 and 44 are in contact with the back surface Sb of the raw material S, and the fifth and sixth transport rolls 25 and 6 are in contact with the surface 201a of the stretched thermoplastic film 201 of the raw material S. Here, the gripping angle of the raw material S by the second transport roll 22, the gripping angle of the raw material S by the third transport roll 23, the gripping angle of the thermoplastic film 201 by the fourth transport roll 24, and the gripping angle of the thermoplastic film 201 by the fifth transport roll 25 are each approximately 90°. As a result, the contact area between each roll and the film (raw material S, thermoplastic film 201) is appropriately wide, allowing the film to be transported while being properly gripped. Here, the gripping angle refers to the angle of the film (raw material S, thermoplastic film 201) from one roll to the next. Therefore, when the wrapping angle is small, the degree to which the film wraps around the roll increases, meaning the contact area between the film and the roll increases, and the grip of the film increases, making the film more susceptible to scratches. On the other hand, when the wrapping angle is large, the degree to which the film wraps around the roll decreases, meaning the contact area between the film and the roll decreases, and the grip of the film decreases, making the film more susceptible to wrinkles during transport. Therefore, it is preferable to set the wrapping angle to an angle that minimizes scratches on the film and prevents wrinkles from forming during transport. Details on the preferred wrapping angle will be described later.

[0023] In this embodiment, the raw material S and the thermoplastic film 201 obtained by stretching the raw material S will be described separately. Specifically, the raw material S is defined as the material that is heated and stretched between the third transport roll 23 and the fourth transport roll 24, and the heated and stretched raw material S is defined as the thermoplastic film 201. In other words, the material is described as the raw material S up to the fourth transport roll 24, and the material that is fed out from the fourth transport roll 24 is described as the thermoplastic film 201.

[0024] The stretching device 101 has a first preheating heater 11a that heats the raw material S from the surface side Sa, and a second preheating heater 11b that heats the raw material S from the back side Sb, positioned between the second conveying roll 22 and the third conveying roll 23. The first preheating heater 11a and the second preheating heater 11b constitute a preheating section 110 that preheats the raw material S before the main heating. The heating temperature of the preheating section 110 is set lower than the heating temperature of the main heating section 120, which will be described later. Therefore, the preheating section 110 does not heat the raw material S enough to stretch it. Details of the heating temperature in the preheating section 110 will be described later.

[0025] Between the third conveyor roll 23 and the fourth conveyor roll 24, a first main heating heater 12a is positioned to heat the raw material S from the front surface Sa side, and a second main heating heater 12b is positioned to heat the raw material S from the back surface Sb side. The first main heating heater 12a and the second main heating heater 12b constitute a main heating section 120 that performs the main heating necessary to stretch the raw material S. Details of the heating temperature in the main heating section 120 will be described later.

[0026] Between the fourth conveyor roll 24 and the fifth conveyor roll 25, a relaxation heater 13 is positioned to heat the thermoplastic film 201 from the surface 201a side. The relaxation heater 13 constitutes a relaxation section 130 that heats the thermoplastic film 201, which has been heated and stretched in the main heating section 120, to a temperature lower than the heating temperature of the main heating section 120. Therefore, the relaxation section 130 does not heat the film enough to stretch the raw material S. Details of the heating temperature in the relaxation section 130 will be described later.

[0027] The first preheating heater 11a, the second preheating heater 11b, the first main heating heater 12a, the second main heating heater 12b, and the relaxation heater 13 are all far-infrared heaters. While it is preferable that the first preheating heater 11a, the second preheating heater 11b, the first main heating heater 12a, the second main heating heater 12b, and the relaxation heater 13 are all far-infrared heaters, the system is not limited to this, and other types of heating heaters may be used.

[0028] Furthermore, from the viewpoint of reducing uneven heating, it is preferable to heat the raw material S from both the front surface Sa and the back surface Sb. Specifically, it is preferable that in the preheating section 110, the front surface Sa of the raw material S is heated by the first preheating heater 11a and the back surface Sb of the raw material S is heated by the second preheating heater 11b, and in the main heating section 120, the front surface Sa of the raw material S is heated by the first main heating heater 12a and the back surface Sb of the raw material S is heated by the second main heating heater 12b. Alternatively, the raw material S may be heated from either the front surface Sa or the back surface Sb by arranging only one of the first preheating heater 11a or the second preheating heater 11b, or only one of the first main heating heater 12a or the second main heating heater 12b.

[0029] In this embodiment, an example is described in which the raw material S and the thermoplastic film 201 are heated using a first preheating heater 11a, a second preheating heater 11b, a first main heating heater 12a, a second main heating heater 12b, and a relaxation heater 13. In the relaxation section 130, only one relaxation heater 13 is provided to heat the thermoplastic film 201 from the surface 201a side, but this is not limited to this, and a heater that heats from the back surface 201b side of the thermoplastic film 201 may also be provided.

[0030] (Heating temperature in each part of the stretching device 101) The first heating heater 12a and the second heating heater 12b in the heating section 120 heat the raw material S stretched between the third conveyor roll 23 and the fourth conveyor roll 24 in the heating section 120 so that the surface temperature of the central part of the raw material S is at or near the glass transition temperature (Tg) of the raw material S. It is preferable that the surface temperature of the central part of the raw material S under heating by the first heating heater 12a and the second heating heater 12b is in the range of <20 degrees Celsius lower than the glass transition temperature (Tg) of the raw material S to 20 degrees Celsius higher than the softening point (Tm) of the raw material S>. Here, the glass transition temperature (Tg) is defined as the temperature at the inflection point when 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, and the correlation between the storage modulus and the measured temperature is plotted. Furthermore, the temperature at which the storage modulus of elasticity becomes 1 / 1000 of the storage modulus of elasticity at the inflection point is defined as the softening point (Tm).

[0031] In the preheating section 110, the first preheating heater 11a and the second preheating heater 11b are used to heat the raw material S stretched between the second conveyor roll 22 and the third conveyor roll 23. The preheating temperature set by the first preheating heater 11a and the second preheating heater 11b is preferably 10°C to 50°C lower than the main heating temperature set by the first and second main heating heaters 12b. If the preheating temperature is 10°C to 50°C lower than the main heating temperature, there is no preheating effect, resulting in uneven heating and wrinkles. Conversely, if the preheating temperature is 10°C to 50°C higher than the main heating temperature, the thermoplastic film 201 may be overheated, causing the raw material S to break.

[0032] The relaxation heater 13 in the relaxation section 130 heats the raw material S such that the surface temperature of the central part of the raw material S stretched between the fourth conveyor roll 24 and the fifth conveyor roll 25 is lower than the surface temperature of the raw material S heated by the first main heating heater 12a and the second main heating heater 12b in the main heating section 120. Preferably, the relaxation temperature by the relaxation heater 13 is 10°C to 50°C lower than the main heating temperature by the first main heating heater 12a and the second main heating heater 12b. If the relaxation temperature is more than 10°C to 50°C lower than the main heating temperature, there is no relaxation effect, uneven heating temperature occurs, and wrinkles may form. On the other hand, if the relaxation temperature is more than 10°C to 50°C higher than the main heating temperature, the thermoplastic film 201 may be overheated, causing the raw material S to break.

[0033] (Control Unit) Figure 2 is a functional block diagram of the film manufacturing apparatus 1. In the film manufacturing apparatus 1, the control unit 2 controls the heating of the preheating section 110, the main heating section 120, and the relaxation section 130. Specifically, the control unit 2 controls the heating of the first preheating heater 11a and the second preheating heater 11b that constitute the preheating section 110, the first main heating heater 12a and the second main heating heater 12b that constitute the main heating section 120, and the relaxation heater 13 that constitutes the relaxation section 130.

[0034] Furthermore, in the film manufacturing apparatus 1, the control unit 2 controls the drive of the first drive motor 140 and the second drive motor 150. Here, the first drive motor 140 drives the first drive roll 31b of the first nip section 31, and the second drive motor 150 drives the second drive roll 32b of the second nip section 32. Therefore, by controlling the drive of the first drive motor 140, the control unit 2 controls the rotational speed of the first drive roll 31b, and by controlling the drive of the second drive motor 150, the control unit 2 controls the rotational speed of the second drive roll 32b.

[0035] In this way, by controlling the rotational speeds of the first drive roll 31b of the first nip section 31 and the second drive roll 32b of the second nip section 32, the transport speed of the raw material S being fed to the third transport roll 23 and the transport speed of the thermoplastic film 201 being fed from the fourth transport roll 24 can be made different. Here, the transport speed of the thermoplastic film 201 being fed from the fourth transport roll 24 is made greater than the transport speed of the raw material S being fed to the third transport roll 23, and this difference in transport speed applies tension in the transport direction to the raw material S between the third transport roll 23 and the fourth transport roll 24. As a result, the raw material S is stretched between the third transport roll 23 and the fourth transport roll 24. At the same time, the first main heating heater 12a and the second main heating heater 12b heat the raw material S between the third transport roll 23 and the fourth transport roll 24. As a result, the raw material S is uniaxially stretched by the third conveyor roll 23 and the fourth conveyor roll 24, and the direction of stretching is the conveying direction.

[0036] Furthermore, due to the above speed difference, tension in the conveying direction is applied to the raw material S and the thermoplastic film 201. As a result, the raw material S is stretched in the longitudinal direction (conveying direction) by the second conveying roll 22 and the third conveying roll 23, and the thermoplastic film 201 is conveyed by the fourth conveying roll 24 and the fifth conveying roll 25 while being stretched in the longitudinal direction (conveying direction).

[0037] (Stretching method) The process of obtaining a thermoplastic film 201 by heating and stretching the raw material S will be described below with reference to Figure 1.

[0038] First, the raw material S fed from the first nip section 31 is conveyed from the first conveyor roll 21 through the second conveyor roll 22 to the third conveyor roll 23. At this time, the raw material S is heated (preliminary heating) between the second conveyor roll 22 and the third conveyor roll 23 by the first preheating heater 11a and the second preheating heater 11b of the preheating section 110. The heated raw material S is then conveyed from the third conveyor roll 23 to the fourth conveyor roll 24. At this time, the raw material S is heated (main heating) between the third conveyor roll 23 and the fourth conveyor roll 24 by the first main heating heater 12a and the second main heating heater 12b of the main heating section 120 (first step).

[0039] In this heating section 120, by making the transport speed of the thermoplastic film 201 fed from the fourth transport roll 24 faster than the transport speed of the raw material S up to the third transport roll 23, tension in the transport direction is applied to the raw material S between the third transport roll 23 and the fourth transport roll 24, the raw material S is stretched in the transport direction, and a thermoplastic film 201 is obtained.

[0040] The thermoplastic film 201 obtained in the heating section 120 is conveyed to the fifth conveyor roll 25 with a gripping angle of 90° by the fourth conveyor roll 24 (second step). The thermoplastic film 201 conveyed from the fourth conveyor roll 24 is heated (heating for relaxation) by the relaxation heater 13 of the relaxation section 130 between the fourth conveyor roll 24 and the fifth conveyor roll 25. The thermoplastic film 201 heated by the relaxation section 130 is conveyed to the sixth conveyor roll 26 with a gripping angle of 90° by the fifth conveyor roll 25. The thermoplastic film 201 conveyed to the sixth conveyor roll 26 is conveyed to a winding roll (not shown) by the second nip section 32.

[0041] The following describes how wrinkles are reduced in the thermoplastic film 201 when using the stretching device 101. Here, Figure 3 is a plan view showing a state in which almost no wrinkles have occurred on both ends 201c of the thermoplastic film 201. Figure 4 is a plan view showing a state in which wrinkles C1 have occurred on both ends 201c of the thermoplastic film 201.

[0042] (Reduction of wrinkle formation (1)) In the stretching apparatus 101, the raw material S is preheated (preliminary heating) by the first preheating heater 11a and the second preheating heater 11b in the preheating section 110 before the main heating by the first main heating heater 12a and the second main heating heater 12b in the main heating section 120. This suppresses a rapid temperature rise in the raw material S when it is main heated, preventing uneven heating of the raw material S caused by a rapid temperature rise during main heating, and thus making it less likely for wrinkles to occur in the thermoplastic film 201 obtained by stretching the raw material S.

[0043] Furthermore, in the stretching apparatus 101, the thermoplastic film 201 obtained by stretching the raw material S after the initial heating is heated (gentle heating) by the relaxation heater 13 in the relaxation section 130. This suppresses a rapid temperature drop in the thermoplastic film 201 and prevents uneven heating of the thermoplastic film 201 caused by a rapid temperature drop, thereby making it less likely for wrinkles to form in the thermoplastic film 201.

[0044] Thus, the stretching apparatus 101 with the above configuration can suppress a rapid temperature rise in the raw material S and a rapid temperature drop in the thermoplastic film 201, thereby reducing the occurrence of wrinkles in the raw material S and thermoplastic film 201 caused by rapid temperature changes.

[0045] (Reducing wrinkle formation (2)) In the stretching device 101, the grip angle of the thermoplastic film 201 by the fourth conveyor roll 24 (second guide roll) is 90°. Here, the raw material S is heated by the first main heating heater 12a and the second main heating heater 12b between the third conveyor roll 23 (first guide roll) and the fourth conveyor roll 24 (second guide roll). Therefore, if the grip angle of the thermoplastic film 201 by the fourth conveyor roll 24, which is located downstream in the conveying direction of the raw material S, is approximately 90°, an appropriate grip force can be applied to the heated thermoplastic film 201. If an appropriate grip force is applied to the thermoplastic film 201, the thermoplastic film 201 can be conveyed without moving in the width direction (direction perpendicular to the conveying direction) relative to the fourth conveyor roll 24, thus making it less likely for wrinkles to occur in the thermoplastic film 201.

[0046] In the stretching device 101, the gripping angle of the thermoplastic film 201 by the fourth conveyor roll 24 may be 90°, but it is acceptable as long as it is within the range of 90° ± 10°. For example, if the gripping angle of the thermoplastic film 201 by the fourth conveyor roll 24 is less than 80°, the contact area between the fourth conveyor roll 24 and the thermoplastic film 201 increases, so the gripping force of the fourth conveyor roll 24 on the thermoplastic film 201 increases, making the thermoplastic film 201 more susceptible to damage. On the other hand, if the gripping angle is greater than 100°, the contact area between the fourth conveyor roll 24 and the thermoplastic film 201 decreases, so the gripping force of the fourth conveyor roll 24 on the thermoplastic film 201 decreases. As a result, the thermoplastic film 201 moves in the width direction (a direction perpendicular to the conveying direction) relative to the fourth conveyor roll 24 during conveying, so wrinkles C1 are more likely to occur on both ends 201c of the thermoplastic film 201 in the width direction, as shown in Figure 3, for example. Therefore, if the gripping force of the fourth transport roll 24 that guides the thermoplastic film 201 after heating is appropriate, a stretched thermoplastic film 201 without wrinkles or scratches can be obtained. In addition, the gripping angles of the film (raw material S, thermoplastic film 201) by the first guide roll, the third transport roll 23, the third guide roll, the second transport roll 22, and the fourth guide roll, the fifth transport roll 25, should be within the range of 90°±10°, similar to the gripping angle of the thermoplastic film 201 by the second guide roll, the fourth transport roll 24.

[0047] Furthermore, in the stretching device 101, assuming that the gripping angle of the thermoplastic film 201 by the fourth conveyor roll 24 is 90°, it is preferable that the diameter of the fourth conveyor roll 24 is 150 mm or more. If the diameter of the fourth conveyor roll 24 is smaller than 150 mm, the contact area between the fourth conveyor roll 24 and the thermoplastic film 201 becomes smaller, the gripping force of the fourth conveyor roll 24 on the thermoplastic film 201 becomes lower, and wrinkles C1 are more likely to occur on both ends 201c of the thermoplastic film 201 that are perpendicular to the stretching direction, as shown in Figure 3.

[0048] The upper limit of the diameter of the fourth conveyor roll 24 shall be set appropriately according to the size of the stretching device 101, the size of the film manufacturing apparatus equipped with the stretching device 101, etc.

[0049] (Reduction of wrinkle formation (3)) In the stretching device 101, the first drive roll 31b of the first nip section 31 and the second drive roll 32b of the second nip section 32 are driven so that the transport speed of the thermoplastic film 201 fed from the fourth transport roll 24 is +0.1% to +10% compared to the transport speed of the raw material S fed to the third transport roll 23. This ensures that the tension on the raw material S between the third transport roll 23 and the fourth transport roll 24 is appropriate, allowing the raw material S to be properly stretched to obtain the thermoplastic film 201. However, if the above speed difference is less than +0.1%, the tension on the raw material S between the third transport roll 23 and the fourth transport roll 24 becomes too small, making it impossible to properly stretch the raw material S in the transport direction. Also, if the above speed difference is greater than +10%, the tension on the raw material S between the third transport roll 23 and the fourth transport roll 24 becomes too large, potentially causing the raw material S to break in the transport direction.

[0050] As described above, the film manufacturing apparatus 1 with the above configuration, by including the stretching device 101 with the above configuration, can produce a thermoplastic film 201 in which the occurrence of wrinkles after heat stretching is reduced.

[0051] 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 in the technical scope of the present invention. [Explanation of Symbols]

[0052] 1. Film manufacturing equipment 2 Control Unit 11a First preheating heater 11b Second preheating heater 12a First heating element 12b Second heating element 13. Relaxation heater 21 First conveyor roll 22. Second conveyor roll (third guide roll) 23. Third conveyor roll (first guide roll) 24. Fourth conveyor roll (second guide roll) 25. Fifth conveyor roll (fourth guide roll) 26. Sixth conveyor roll 31. First Nip Section 31a First Nip Roll 31b First drive roll 32 Second Nip Section 32a Second Nip Roll 32b Second drive roll 101 Stretching device 110 Preheating section 120 heating parts 130 Relaxation section 140 First drive motor 150 Second drive motor 201 Thermoplastic film 201a surface 201b back side 201c Both ends C1 Wrinkles S Original fabric Sa surface Sb (backside)

Claims

1. A stretching apparatus that heats and stretches a film made of thermoplastic resin while conveying it, A first guide roll that guides the transport of the aforementioned film, A second guide roll is positioned downstream of the first guide roll in the film transport direction, at a predetermined distance from the first guide roll, The system includes a heating element that heats the film to stretch it between the first guide roll and the second guide roll, The angle at which the film is gripped by the second guide roll is 90° ± 10°, and further, A stretching device comprising a relaxation heater positioned downstream of the second guide roll in the film transport direction, which heats the film to a temperature lower than that of the main heating heater.

2. A stretching apparatus for heating and stretching a film made of a thermoplastic resin while conveying it, A first guide roll that guides the transport of the aforementioned film, A second guide roll is positioned downstream of the first guide roll in the film transport direction, at a predetermined distance from the first guide roll, The system includes a heating element that heats the film to stretch it between the first guide roll and the second guide roll, The angle at which the film is gripped by the second guide roll is 90° ± 10°, and further, A preheating heater is positioned upstream of the first guide roll in the film transport direction and heats the film to a temperature lower than that of the main heating heater, A stretching device comprising a relaxation heater positioned downstream of the second guide roll in the film transport direction, which heats the film to a temperature lower than that of the main heating heater.

3. The stretching apparatus according to claim 2, wherein the heating temperature by the preheating heater is 10°C to 50°C lower than the main heating temperature by the main heating heater.

4. The stretching apparatus according to claim 2 or 3, wherein the main heating heater and the preheating heater are provided on the front and back sides of the film, respectively.

5. The stretching apparatus according to any one of claims 2 to 4, wherein the main heating heater, the preheating heater, and the relaxation heater are far-infrared heaters.

6. The stretching apparatus according to any one of claims 1 to 5, wherein the relaxation temperature by the relaxation heater is 10°C to 50°C lower than the main heating temperature by the main heating heater.

7. A third guide roll is positioned upstream of the first guide roll in the film transport direction and guides the film toward the first guide roll. The system further comprises a fourth guide roll positioned downstream of the second guide roll in the film transport direction, which guides the transport of the film fed from the second guide roll further downstream in the transport direction, The first guide roll and the third guide roll stretch the film in the longitudinal direction, A stretching apparatus according to any one of claims 1 to 6, wherein the film is stretched in the longitudinal direction by the second guide roll and the fourth guide roll.

8. The stretching apparatus according to any one of claims 1 to 7, wherein the diameter of the second guide roll is 150 mm or more.

9. The stretching apparatus according to any one of claims 1 to 8, wherein the transport speed of the film fed from the second guide roll is set to a speed difference of +0.1% to +10% with respect to the transport speed of the film fed to the first guide roll.

10. A method for stretching a film made of a thermoplastic resin, comprising heating and stretching the film while transporting it, The first step involves heating the film using a heating heater between a first guide roll that guides the transport of the film and a second guide roll positioned at a predetermined distance downstream in the transport direction of the film. The second step involves the second guide roll feeding out the film that has been heated in the first step at an angle of 90° ± 10°, A stretching method comprising: a third step of gently heating the film fed out in the second step at a temperature lower than that of the heating heater.

11. A film manufacturing apparatus comprising a stretching device according to any one of claims 1 to 9.

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