Stretched film manufacturing apparatus

Abstract

A first pressing portion (60) formed by a central roll surface (50a) (first pressing region) of the contact roll (20a) (first roll) and a roll surface (21a) of the No. 2 roll (21) (second roll) presses the first thermoplastic resin and the second thermoplastic resin fed from the T die (24) (feeding portion). A second pressing portion (61) formed by end roll surfaces (50b, 50c) (second pressing region) of the contact roll and the roll surface (21a) of the No. 2 roll (21) presses the second thermoplastic resin fed to both ends in the width direction of the first thermoplastic resin with a lower force than the first pressing portion (60). The formed film is cooled by the No. 2 roll (21) and the No. 3 roll (22) (third roll) constituting a cooling portion (62), and a two-axis simultaneous stretching device (14) (stretching portion) grips the region of the second thermoplastic resin and stretches in the moving direction and the width direction orthogonal to the moving direction.

Description

TECHNICAL FIELD

[0001] The present application relates to a stretched film manufacturing apparatus using a contact roller. BACKGROUND

[0002] The thickness precision of a film such as an optical film becomes important, and thus film formation is generally performed by contact roller molding.

[0003] Then, both ends of the film molded by the contact roller molding are held by a jig, and are stretched in a moving direction (longitudinal direction) and a width direction (lateral direction). At this time, stress is concentrated on the end portions of the film, and thus a crack is generated, and the film can be broken.

[0004] Therefore, for example, the stretched film manufacturing apparatus described in Patent Literature 1 has an end portion multi-column film using a polycarbonate resin or the like as a reinforcing material molded at the end portion of the molded film.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent No. 6377354

[0008] Patent Literature 2: Japanese Patent Application Laid-Open No. 11-105131 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] However, in the contact portion of the contact roller, since the formation state of the accumulation (resin accumulation portion) is different between the end portion and the central portion of the film, a wrinkled or rough portion is generated at the end portion in the pressing process or the cooling and solidifying process based on the contact roller. In the wrinkled or rough portion thus generated, since stress is concentrated at the time of stretching the film, it becomes a main cause of breakage. Therefore, in Patent Literature 1, a finishing process (smoothing process) for removing the uneven portion of both end portions of the molded end portion multi-column film is provided before the film is stretched. However, the finishing process requires labor and time, and there is a problem that the productivity is reduced due to breakage of the film caused by the finishing work.

[0011] In addition, in Patent Literature 2, open molding for molding the film is performed without using a roller press. However, the film molded by the open molding has a problem that the thickness precision and the smoothness of the surface are worse than those of the film molded by the contact roller.

[0012] The present application has been achieved in view of the above-described circumstances, and aims to provide a stretched film manufacturing apparatus which does not break even if a finishing process is not provided before stretching, does not generate a wrinkled portion at the end portion, and can manufacture a stretched film having high thickness precision.

[0013] Means for solving the problem

[0014] To solve the above problem and achieve the object, the film stretching apparatus according to the present application is characterized by comprising: a feeding section that feeds a molten first thermoplastic resin to a central portion in a width direction and feeds a molten second thermoplastic resin to both end portions in the width direction of the first thermoplastic resin; a first pressing section that presses the first thermoplastic resin and the second thermoplastic resin fed from the feeding section at a first pressing region of a first roller and a second roller; a second pressing section that presses the second thermoplastic resin fed from the feeding section at a second pressing region of both ends of the first pressing region of the first roller and the second roller at a lower pressing force than the first pressing region; a cooling section that cools the first thermoplastic resin and the second thermoplastic resin by passing the first thermoplastic resin and the second thermoplastic resin between the second roller and a third roller disposed on the opposite side of the first roller with the second roller interposed therebetween after the first thermoplastic resin and the second thermoplastic resin are pressed by the first roller and the second roller; and a stretching section that stretches a film formed of the first thermoplastic resin and the second thermoplastic resin after being cooled by the cooling section by holding regions of the second thermoplastic resin at both ends of the film in a moving direction and a width direction orthogonal to the moving direction.

[0015] Effects of the Invention

[0016] The film stretching apparatus according to the present application has the effect that the film is not broken even if a trimming process is not provided before stretching, and wrinkles are not generated at the end portions, and a film with high thickness precision can be manufactured. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a general view of the film stretching apparatus according to the first embodiment.

[0018] Figure 2 is a side view of a pressing device provided in the film stretching apparatus according to the first embodiment.

[0019] Figure 3 is a plan view of a pressing section and a cooling section.

[0020] Figure 4 is a plan view of a pressing section and a cooling section of a film stretching apparatus according to a modified example of the first embodiment.

[0021] Figure 5 is a plan view of a pressing section and a cooling section of a film stretching apparatus according to a modified example of the second embodiment.

[0022] Figure 6 is a plan view of a pressing section and a cooling section of a film stretching apparatus according to a modified example of the second embodiment. DETAILED DESCRIPTION

[0023] Hereinafter, an embodiment of the elongated film manufacturing apparatus of the present application will be described in detail based on the drawings. Note that the present application is not limited to this embodiment. Also, the components in the following embodiment include components that can be substituted and easily conceived by those skilled in the art, or substantially the same components.

[0024] (First Embodiment)

[0025] [Explanation of the outline configuration of the elongated film manufacturing apparatus]

[0026] First, the use of the terms "longitudinal direction" and "transverse direction" will be explained. Figure 1 The overall configuration of the elongated film manufacturing apparatus 10 in the first embodiment will be explained. Figure 1 is a general view of the elongated film manufacturing apparatus of the first embodiment.

[0027] The elongated film manufacturing apparatus 10 is provided with a pressing apparatus 12 and a two-axis simultaneous elongation apparatus 14. Note that the elongated film manufacturing apparatus 10 can also be provided with a sequential elongation apparatus that sequentially elongates a film in the longitudinal direction and the transverse direction. The following explanation will be given with the two-axis simultaneous elongation apparatus 14 provided.

[0028] The pressing apparatus 12 is provided with a T die 24, a contact roller 20a, a No. 2 roller 21, a No. 3 roller 22, and a conveyance roller 23.

[0029] The T die 24 feeds hot plastic resin (hereinafter, referred to as molten hot plastic resin) that is a material of a film, which is melted in an extruder not shown, between the contact roller 20a and the No. 2 roller 21 that rotate in a state of abutting against the roller surfaces. Note that the T die 24 is an example of the feeding portion in the present disclosure.

[0030] The contact roller 20a is a substantially cylindrical roller that presses the molten hot plastic resin fed from the T die 24 by being sandwiched between the No. 2 roller 21. The contact roller 20a is rotationally driven by an electric motor 25a controlled by a control device not shown. Note that the contact roller 20a adjusts the pressing force against the No. 2 roller 21 by a pressing force adjustment machine 26, such as one provided with a cylinder and a piston controlled by oil pressure, controlled by a control device not shown. Note that the contact roller 20a is an example of the first roller in the present disclosure. Note that the detailed shape of the contact roller 20a will be described later (see Figure 4 ).

[0031] A hot medium (hereinafter, referred to as a hot medium), such as cooling water, cooling oil, or the like, circulates inside the contact roller 20a, and the molten hot plastic resin is sandwiched between the contact roller 20a and the No. 2 roller 21 and is cooled while being pressed.

[0032] The No. 2 roll 21 is a cylindrical roll that presses by sandwiching the molten thermoplastic resin fed from the T die 24 between the contact roll 20a. The No. 2 roll 21 is rotationally driven by an electric motor 25b controlled by a control device not shown. In addition, the No. 2 roll 21 is an example of the second roll in the present disclosure.

[0033] A heat medium such as cooling water, cooling oil, or the like circulates inside the No. 2 roll 21, and the molten thermoplastic resin is sandwiched between the contact roll 20a and pressed while being cooled.

[0034] The No. 3 roll 22 is a cylindrical roll in which a heat medium such as cooling water, cooling oil, or the like circulates inside. The No. 3 roll 22 is disposed on the opposite side of the contact roll 20a with the No. 2 roll 21 interposed therebetween (see FIG. 2). The No. 3 roll 22 cools by sandwiching the molten thermoplastic resin shaped into a film between the No. 2 roll 21. The No. 3 roll 22 is rotationally driven by an electric motor 25c controlled by a control device not shown. In addition, the No. 3 roll 22 is an example of the third roll in the present disclosure. Figure 2

[0035] The transport roll 23 is a cylindrical roll that extends the moving direction of the film S pressed and cooled toward the direction of the inlet la of the two-axis simultaneous stretching device 14.

[0036] The two-axis simultaneous stretching device 14 has, in left and right, annular rings 15R and 15L that hold the film S with a plurality of clamps 30, in left and right, symmetrically when viewed from above. The film S that is the stretching target is fed from the inlet la and discharged from the outlet lb in a stretched state. In addition, the annular ring on the right when viewed from the inlet la side of the film S that is the stretching target is referred to as the right annular ring 15R, and the annular ring on the left is referred to as the left annular ring 15L. In addition, the film S is, for example, a resin film having thermoplasticity. In addition, for the following description, a coordinate system XYZ shown in FIG. 1 is set. The X axis is the axial direction of the contact roll 20a, the No. 2 roll 21, the No. 3 roll 22, the transport roll 23, and the width direction of the film S. The Y axis is the moving direction of the film S in the two-axis simultaneous stretching device 14. The Z axis is the direction orthogonal to the X axis and the Y axis. In addition, the two-axis simultaneous stretching device 14 is an example of the stretching portion in the present disclosure. Figure 1 The clamps 30 are respectively attached to one end portion (positions facing each other between the inlet la and the outlet lb) of the length direction of the rectangular clamp carrying member 31. That is, the facing pair of clamps 30 are disposed at both ends in the width direction of the film S that is the stretching target, and function as a holding device that holds the stretching target.

[0037]

[0038] ​​The clamping support component 31 is guided by the reference track 40 and moves in a circular motion. The right annular ring 15 moves in a clockwise direction, and the left annular ring 15L moves in a counterclockwise direction. Specifically, the drive rollers (not shown) of the clamping support component 31 selectively engage with the drive sprockets 32 and 33, causing each clamping support component 31 to travel along the circular path. That is, the drive sprockets 32 and 33 selectively engage with the drive rollers of each clamping support component 31, and are driven by the rotation of an electric motor, which applies a force to the clamping support component 31 to travel along the circular path. Specifically, the two drive sprockets 33 are driven by the rotational driving force of the electric motor 34 after being reduced by a reducer (not shown). The two drive sprockets 32 are reduced in opposite directions by two reducers (not shown), and are driven by the rotational driving force of the electric motor (not shown).

[0039] If the distance between the reference track 40 of the right annular ring 15R and the reference track 40 of the left annular ring 10L increases, the membrane S extends laterally (in the X-axis direction).

[0040] Adjacent clamping components 31 are connected to each other by a clamping linkage mechanism 35 consisting of multiple links. The clamping linkage mechanism 35 is guided by a spacing setting track 41, which moves the clamping components 31 in a circular motion.

[0041] The clamping linkage mechanism 35 sets the interval between adjacent clamping support members 31 (hereinafter referred to as clamping spacing) based on the distance between the reference track 40 and the spacing setting track 41. The larger the clamping spacing, the more the membrane S extends longitudinally (Y-axis direction) in a direction orthogonal to the width direction, which is the moving direction of the clamping support member 31. Furthermore, Figure 1 This diagram illustrates the extension of membrane S, fed from inlet 1a, along the longitudinal and transverse axes. For ease of understanding, membrane S is depicted discontinuously, but in reality, membrane S is continuous from inlet 1a to outlet 1b.

[0042] The dual-axis simultaneous extension device 14 has a preheating zone A, an extension zone B, and a heat treatment zone C extending from the inlet 1a side of the membrane S toward the outlet 1b side.

[0043] In preheating zone A, the spacing (separation distance) of the reference tracks 40 of the left annular ring 15L and the right annular ring 15R is set to correspond to the initial width of the lateral extension, and the left annular ring 15L and the right annular ring 15R are arranged parallel to each other throughout the zone. Furthermore, in the left annular ring 15L and the right annular ring 15R, the spacing between the reference track 40 and the spacing setting track 41 corresponds to the initial spacing of the longitudinal extension.

[0044] In the extension region B, the separation distance of the left and right annular rings 15L and 15R is gradually expanded as going from the preheating region A side toward the heat treatment region C, and the left and right annular rings 15L and 15R are disposed non-parallel. The separation distance of the left and right annular rings 15L and 15R in the extension region B is set to correspond to the initial width of the lateral extension at the extension start end (the connecting end with the preheating region A) and to the final width of the lateral extension at the extension end (the connecting end with the heat treatment region C). That is, in the extension region B, the interval of the reference tracks 40 of the left annular ring 15L and the reference tracks 40 of the right annular ring 15R is gradually expanded as going from the preheating region A side toward the heat treatment region C. The interval of the respective reference tracks 40 corresponds to the initial width of the lateral extension at the extension start end (the connecting end with the preheating region A) and to the final width of the lateral extension at the extension end (the connecting end with the heat treatment region C).

[0045] Further, in the extension region B, the interval of the reference tracks 40 and the pitch setting tracks 41 of the left annular ring 15L is gradually reduced as going from the preheating region A side toward the heat treatment region C. Also, the interval of the reference tracks 40 and the pitch setting tracks 41 of the right annular ring 15R is similarly gradually reduced. The interval of the reference tracks 40 and the pitch setting tracks 41 corresponds to the initial pitch of the longitudinal extension at the extension start end (the connecting end with the preheating region A) and to the final pitch of the longitudinal extension at the extension end (the connecting end with the heat treatment region C). That is, the two-axis simultaneous extension device 14 simultaneously performs the longitudinal extension and the lateral extension of the film S in the extension region B.

[0046] In the heat treatment region C, the separation distance of the left and right annular rings 15L and 15R is set to correspond to the final width of the lateral extension, and the left and right annular rings 15L and 15R are disposed parallel to each other in the entire region. Also, the interval of the reference tracks 40 and the pitch setting tracks 41 is set to correspond to the final pitch of the longitudinal extension, and the reference tracks 40 and the pitch setting tracks 41 are disposed parallel to each other in the entire region.

[0047] [Explanation of detailed structure of pressing device]

[0048] Next, the detailed structure of the pressing device 12 that presses the molten thermoplastic resin will be explained. Figure 2 、 Figure 3 The detailed structure of the pressing device 12 that presses the molten thermoplastic resin will be explained. Figure 2 is a side view of the pressing device of the extension film manufacturing apparatus of the first embodiment. Figure 3 is a plan view of the pressing portion and the cooling portion.

[0049] As Figure 3As shown, the molten thermoplastic resin 28 fed from the T-shaped mold 24 toward the Z-axis has a multi-row structure with acrylic resin 28a disposed in the central part and polycarbonate resin 28b disposed at both ends.

[0050] The molten thermoplastic resin 28 is introduced into the rotation axis 27a in a clockwise direction. Figure 2 The contact roller 20a rotates in the direction of arrow K1 and rotates counterclockwise around the rotation axis 27b. Figure 2 The contact surface of the No.2 roller 21 rotates in the direction of arrow K2. As the contact roller 20a is pressed towards the No.2 roller 21 by the pressure adjuster 26, the molten thermoplastic resin 28 is clamped and pressed by the contact roller 20a and the No.2 roller 21.

[0051] Furthermore, the molten thermoplastic resin 28 is cooled by a heat medium circulating inside the contact roller 20a and another heat medium circulating inside the No.2 roller 21. These heat media are controlled to a temperature near the glass transition point of the molten thermoplastic resin 28. And, by setting the heat medium circulating inside the No.2 roller 21 to a slightly higher temperature than the heat medium circulating inside the contact roller 20a, the molten thermoplastic resin 28 pressed by the contact roller 20a and the No.2 roller 21 moves together with the surface (roller surface) of the No.2 roller 21, which has a higher temperature, in the positive Y-axis direction.

[0052] Then, the molten thermoplastic resin 28 is cooled by being sandwiched between the No.2 roller 21 and the No.3 roller 22, which rotates clockwise (in the direction of arrow K3) around the rotation axis 27c. In addition, the heat medium circulating inside the No.3 roller 22 is set to a higher temperature than the heat medium circulating inside the No.2 roller 21, thereby causing the molten thermoplastic resin 28 (film S) sandwiched between the No.2 roller 21 and the No.3 roller 22 to move together with the surface (roller surface) of the No.3 roller 22, which has a higher temperature, in the positive Y-axis direction.

[0053] After the above processes, the film S is formed from the molten thermoplastic resin 28.

[0054] Furthermore, the extended film manufacturing apparatus 10 in this embodiment manufactures multiple rows of end films, with polycarbonate resin forming both ends of the film S in the width direction and acrylic resin forming the central portion in the width direction. Generally, polycarbonate resin has a higher strength than acrylic resin. Therefore, even when the clamps 30 provided in the dual-axis simultaneous extending apparatus 14 hold the two ends of the formed film S in the width direction formed by polycarbonate resin and extend it in the moving direction and width direction of the film S, it is possible to extend it at a predetermined ratio in the longitudinal and transverse directions without causing the film S to break.

[0055] [Explanation of the function of the pressing device]

[0056] Next, use Figure 3 The operation of the pressing device 12 will be explained. In the roller surface of the contact roller 20a, the central roller surface 50a in the central portion is crowned. Normally, when pressing the roller, the pressing force may decrease due to the roller's own deflection. To achieve uniform pressing force, a process is performed that makes the central portion of the roller coarser than the ends of the roller. This is crowning. Furthermore, the cross-section of the rotation axis of the roller formed by the crowning process has a curve shape such as a quadratic curve, a quartic curve, or a sine curve, referred to as a crown curve. The central roller surface 50a is pressed against the No.2 roller 21, which has a cylindrical roller surface 21a, thereby forming the first pressing portion 60. In this embodiment, a portion of the acrylic resin 28a and the polycarbonate resin 28b are pressed into the first pressing portion 60 against the central roller surface 50a of the contact roller 20a and the roller surface 21a of the No.2 roller 21. Furthermore, the central roller surface 50a and the roller surface 21a opposite to the central roller surface 50a are examples of the first pressing region in this disclosure.

[0057] Furthermore, the end roller surfaces 50b and 50c on both ends of the roller surface of the contact roller 20a are processed into a tapered shape, with the diameter of the contact roller 20a gradually decreasing towards both ends of the contact roller 20a. The end roller surfaces 50b and 50c are pressed against the roller surface 21a of the No.2 roller 21, forming a second pressing portion 61 on both ends of the first pressing portion 60. In this embodiment, a portion of the polycarbonate resin 28b is pressed into the second pressing portion 61 with a lower pressing force than that of the first pressing portion 60 onto the end roller surfaces 50b and 50c of the contact roller 20a and the roller surface 21a of the No.2 roller 21. Therefore, the thickness of the polycarbonate resin 28b in the second pressing portion 61 is formed to be thicker than the thickness of the acrylic resin 28a and the polycarbonate resin 28b pressed by the first pressing portion 60. For example, relative to the thickness of the film S formed by the first pressing portion 60, the film S is formed to a thickness of approximately 50 μm in the second pressing portion 61. Furthermore, the end roller surfaces 50b and 50c, and the roller surface 21a opposite to the end roller surfaces 50b and 50c, are an example of the second pressing region in this disclosure.

[0058] exist Figure 3 The diagram shows an enlarged view of the central roller surface 50a and the end roller surface 50c of the contact roller 20a. However, the central roller surface 50a, which is crowned, has a tangent inclination angle θ1 at its end. Similarly, the end roller surface 50c, which is tapered, has an inclination angle θ2. Then, in the pressing device 12, angles θ2 and θ1 are processed to be approximately equal. By processing in such a way that θ1≈θ2, the cross-sectional shape can be approximated to that of a conventionally crowned contact roller, thus enabling uniform pressing pressure in the width direction of the contact roller 20a.

[0059] The molten thermoplastic resin 28 pressed by the contact roller 20a and the No. 2 roller 21 is then cooled by the cooling section 62 formed by the roller face 21a of the No. 2 roller 21 and the roller face 22a of the No. 3 roller 22. Here, in order to cool the molten thermoplastic resin 28, the molten thermoplastic resin 28 can be brought into contact with the roller face 21a of the No. 2 roller 21 and the roller face 22a of the No. 3 roller 22, or the molten thermoplastic resin 28 can be made to pass only between the roller face 21a and the roller face 22a. In addition, the roller face 21a of the No. 2 roller 21 and the roller face 22a of the No. 3 roller 22 are each preferably a cylindrical face.

[0060] The molten thermoplastic resin 28 cooled by the roller face 21a of the No. 2 roller 21 and the roller face 22a of the No. 3 roller 22 is discharged from the No. 3 roller 22 as a film S. As shown in FIG. 4, on the film S, a region Sa pressed by the first pressing section 60 at a high pressing force, and regions Sb, Sc pressed by the second pressing section 61 at a low pressing force are formed. In the case of the present embodiment, the region Sa is formed of the acrylic resin 28a and the polycarbonate resin 28b, and the regions Sb, Sc are formed of the polycarbonate resin 28b. Then, the film S is guided by the above-described conveyance roller 23 (refer to FIG. 2), and is fed into the inlet la of the two-axis simultaneous stretching device 14. Figure 3 Figure 2

[0061] The film S fed into the two-axis simultaneous stretching device 14 has the regions at both ends in the width direction (X-axis direction) formed of the polycarbonate resin 28b held by the jigs 30 (refer to FIG. 2), and is stretched in the moving direction (Y direction) and the width direction. Figure 1

[0062] In addition, from the viewpoint of surface smoothness and thickness uniformity, the contact roller 20a is preferably a metal rigid roller. Also, on the central roller face 50a and the end roller faces 50b, 50c, a high-hardness film is formed by HCr (hard chrome plating) processing. In addition, the contact roller 20a can be an elastic roller such as a metal elastic roller.

[0063] In addition, in the above-described embodiment, an example in which both end portions of the roller face of the contact roller 20a are processed into a tapered shape, and the central portion of the roller face of the contact roller 20a is crown-processed, is described, but even if the contact roller 20a is shaped into a cylindrical shape, and the No. 2 roller 21 is shaped into a cylindrical shape, the same effects can be obtained. Figure 3 Figure 3 ​​​​The same effect can be obtained if the No. 2 roll 21 is tapered on the side of the contact roll 20a. However, if the No. 2 roll 21 is tapered, the contact between the No. 2 roll 21 and the No. 3 roll 22 is reduced, and thus the cooling performance of the molten thermoplastic resin 28 can be reduced. Therefore, the tapering is preferably performed on the side of the contact roll 20a. Since the No. 2 roll 21 cannot be removed, the roll cleaning device is installed to clean the No. 2 roll 21. If the No. 2 roll 21 is tapered, the contact of the cleaner with the No. 2 roll 21 is weak when the roll cleaning device is installed, and thus wiping residue and uneven wiping can occur. Therefore, the No. 2 roll 21 is preferably flat in the width direction.

[0064] As described above, in the stretched film manufacturing apparatus 10, the first pressing portion 60 formed by the central roll surface 50a (first pressing region) of the contact roll 20a (first roll) and the roll surface 21a (first pressing region) of the No. 2 roll 21 (second roll) presses the acrylic resin 28a (first thermoplastic resin) fed from the T die 24 (feeding portion) with a high pressing force. Further, the second pressing portion 61 formed by the end roll surfaces 50b, 50c (second pressing region) of the contact roll 20a (first roll) and the roll surface 21a (second pressing region) of the No. 2 roll 21 (second roll) presses the polycarbonate resin 28b (second thermoplastic resin) fed from the T die 24 (feeding portion) on both end sides of the acrylic resin 28a with a lower pressing force than the first pressing region. Further, the cooling portion 62 cools by sandwiching the acrylic resin 28a and the polycarbonate resin 28b with the No. 2 roll 21 (second roll) and the No. 3 roll 22 (third roll). Further, the two-axis simultaneous stretching apparatus 14 (stretching portion) grips the regions of the polycarbonate resin 28b on both ends of the film S formed of the acrylic resin 28a and the polycarbonate resin 28b after cooled by the cooling portion 62, and stretches the film S in the moving direction and the width direction orthogonal to the moving direction. Therefore, since the portions where stress is concentrated when the stretched film S is formed are not present, a trimming process before stretching is not required. Further, since the end portions of the thermoplastic resin are pressed with a low pressure, the generation of wrinkles can be suppressed, and the polycarbonate resin 28b on the end portions of the film S is stronger than the acrylic resin 28a, and thus does not break during stretching. Therefore, a stretched film with high thickness accuracy can be manufactured. Further, since a trimming process is not required, the apparatus can be simplified and downsized, and a process for the film removed in the trimming process is not required. Furthermore, since the amount of the polycarbonate resin 28b formed on the end portions is the minimum necessary amount, the yield is improved.

[0065] Further, in the stretched film manufacturing apparatus 10, the end roll surfaces 50b, 50c (second pressing regions) of the contact roll 20a (first roll) are formed so that the diameter of the contact roll 20a decreases toward both ends. Therefore, the molten thermoplastic resin 28 that is fed is pressed at a lower pressing force in the second pressing regions than in the first pressing region. Thus, it is possible to form both ends of the film S to be thicker than the center portion.

[0066] Further, in the stretched film manufacturing apparatus 10, the first pressing portion 60 of the contact roll 20a (first roll) is crown processed. Therefore, in the first pressing portion 60, it is possible to reliably press the contact roll 20a against the No. 2 roll 21 (second roll).

[0067] Further, in the stretched film manufacturing apparatus 10, the inclination of the tangent line of the central roll surface 50a (first pressing region) in the end portion of the central roll surface 50a when the contact roll 20a (first roll) is cut with a face including the roll shaft of the contact roll 20a is substantially equal to the inclination of the end roll surfaces 50b, 50c (second pressing regions) of the contact roll 20a. Therefore, it is possible to approximate the cross-sectional shape of the conventional contact roll that is crown processed, and thus it is possible to make the pressing force in the width direction of the contact roll 20a uniform.

[0068] Further, in the stretched film manufacturing apparatus 10, the contact roll 20a (first roll) is a metal rigid roll or an elastic roll. Therefore, in the first pressing portion 60, it is possible to reliably press the molten thermoplastic resin 28.

[0069] Further, in the stretched film manufacturing apparatus 10, the contact roll 20a (first roll), the No. 2 roll 21 (second roll), and the No. 3 roll 22 (third roll) internally contain a heat medium. Therefore, it is possible to reliably cool the fed molten thermoplastic resin 28.

[0070] Further, in the stretched film manufacturing apparatus 10, the first thermoplastic resin is an acrylic resin, and the second thermoplastic resin is a polycarbonate resin. Therefore, it is possible to reinforce the end portions of the film S without generating wrinkles or rough portions.

[0071] [Modified Example of the First Embodiment]

[0072] Next, a modified example of the first embodiment will be described. Figure 4 A modified example of the first embodiment will be described. Figure 4 is a plan view of a pressing portion and a cooling portion of a stretched film manufacturing apparatus of the modified example of the first embodiment.

[0073] This embodiment is an example in which the contact roll 20b is used instead of the contact roll 20a in the first embodiment. The central roll surface 50d (first pressing region) of the contact roll 20b is not crown processed, and forms a cylindrical surface.

[0074] The contact roller 20b is pressed against the No. 2 roller 21, thereby shaping the film S from the molten thermoplastic resin 28 that is fed. At this time, the central portion of the acrylic resin 28a and a portion of the polycarbonate resin 28b are pressed with a higher pressing force, and the both end portions of the polycarbonate resin 28b are pressed with a lower pressing force. Thus, as in the first embodiment, the both end portions of the polycarbonate resin 28b are formed thicker than the central portion of the acrylic resin 28a.

[0075] (Second Embodiment)

[0076] Next, a second embodiment of the present disclosure will be described using Figure 5 . Figure 5 is a plan view of a pressing portion and a cooling portion of an extended film manufacturing apparatus of a modification example of the second embodiment.

[0077] This embodiment is an example in which the contact roller 20c is used instead of the contact roller 20a in the first embodiment. The contact roller 20c is provided with end roller surfaces 50e, 50f instead of the end roller surfaces 50b, 50c (see Figure 3 ). The end roller surfaces 50e, 50f form cylindrical surfaces with a smaller diameter with respect to the crown-processed central roller surface 50a. That is, a step is formed between the central roller surface 50a and the end roller surfaces 50e, 50f.

[0078] When the contact roller 20c is pressed against the No. 2 roller 21, the central roller surface 50a of the contact roller 20c is pressed against the roller surface 21a of the No. 2 roller 21, forming a first pressing portion 60. In addition, the end roller surfaces 50b, 50c of the contact roller 20c are pressed against the roller surface 21a of the No. 2 roller 21, forming a second pressing portion 61.

[0079] At this time, the first pressing portion 60 is pressed with a higher pressing force, and the second pressing portion 61 is pressed with a lower pressing force. Thus, a portion (regions Sb, Sc) of the polycarbonate resin 28b of the both end portions of the molten thermoplastic resin 28 is formed thicker than a portion (region Sa) of the acrylic resin 28a and the polycarbonate resin 28b of the central portion.

[0080] [Modification Example of the Second Embodiment]

[0081] Next, a modification example of the second embodiment will be described using Figure 6 . Figure 6 is a plan view of a pressing portion and a cooling portion of an extended film manufacturing apparatus of a modification example of the second embodiment.

[0082] This embodiment is an example in which the contact roller 20d is used instead of the contact roller 20c in the second embodiment. The contact roller 20d does not crown-process the central roller surface 50d (first pressing region), but forms a cylindrical surface.

[0083] The contact roller 20d is pressed against the No. 2 roller 21, whereby the film S is formed from the fed molten thermoplastic resin 28. At this time, a portion (region Sa) of the acrylic resin 28a and the polycarbonate resin 28b in the central portion is pressed with a higher pressing force, and a portion (regions Sb, Sc) of the polycarbonate resin 28b in the both end portions is pressed with a lower pressing force. Thus, as with the second embodiment, a portion of the polycarbonate resin 28b in the both end portions is formed thicker than the acrylic resin 28a and the portion of the polycarbonate resin 28b in the central portion.

[0084] As explained above, in the stretched film manufacturing apparatus 10, the contact roller 20c (first roller) end portion roller surfaces 50e, 50f (second pressing region) are formed by cylindrical surfaces having a smaller diameter than the central roller surface 50a (first pressing region) of the contact roller 20c. Thus, the fed molten thermoplastic resin 28 is pressed with a lower pressing force in the second pressing region than in the first pressing region. Thereby, the both end portions of the film S can be formed thicker than the central portion.

[0085] Symbol explanation

[0086] 10... stretched film manufacturing apparatus, 12... pressing device (first pressing portion, second pressing portion, cooling portion), 14... two-axis simultaneous stretching device (stretching portion), 15L... left side endless loop, 15R... right side endless loop, 20a, 20b, 20c, 20d... contact roller (first roller), 21... No. 2 roller (second roller), 21a... roller surface (first pressing region, second pressing region), 22... No. 3 roller (third roller), 22a... roller surface, 23... conveyance roller, 24... T die (feeding portion), 25a, 25b, 25c... electric motor, 28... molten thermoplastic resin, 28a... acrylic resin (first thermoplastic resin), 28b... polycarbonate resin (second thermoplastic resin), 30... clamp, 31... clamp carrying member, 35... clamp link mechanism, 40... reference rail, 41... pitch setting rail, 50a, 50d... central roller surface (first pressing region), 50b, 50c, 50e, 50f... end portion roller surface (second pressing region), 60... first pressing portion, 61... second pressing portion, 62... cooling portion, A... preheating region, B... stretching region, C... heat treatment region, S... film, Sa, Sb, Sc... region.

Claims

1. An extended film manufacturing apparatus comprising: a feeding section that feeds a molten first thermoplastic resin to a widthwise central portion and feeds a molten second thermoplastic resin to both widthwise end portions of the first thermoplastic resin; a first pressing section that presses the first thermoplastic resin and the second thermoplastic resin fed from the feeding section in a first pressing region formed by a first roller and a second roller; a second pressing section that presses the second thermoplastic resin at both widthwise ends of the second thermoplastic resin pressed by the first pressing section in a second pressing region formed by the first roller and the second roller on both end portions of the first pressing region in a manner of being thicker than the first pressing region; a cooling section that cools the first thermoplastic resin and the second thermoplastic resin by passing the first thermoplastic resin and the second thermoplastic resin between the second roller and a third roller disposed on an opposite side of the first roller with the second roller interposed therebetween after the first thermoplastic resin and the second thermoplastic resin are pressed by the first roller and the second roller; and an extending section that extends a film formed of the first thermoplastic resin and the second thermoplastic resin after being cooled by the cooling section in a moving direction and a widthwise direction orthogonal to the moving direction.

2. The extended film manufacturing apparatus according to claim 1, wherein the second pressing region of the first roller is formed such that a diameter of the first roller decreases toward both end portions.

3. The extended film manufacturing apparatus according to claim 1, wherein the second pressing region of the first roller is formed by a cylindrical surface having a smaller diameter than the first pressing region of the first roller.

4. The extended film manufacturing apparatus according to claim 2 or 3, wherein the first pressing region of the first roller is crown processed.

5. The extended film manufacturing apparatus according to claim 2, wherein when the first roller is cut with a face including a roller shaft of the first roller, a gradient of a tangent line of the first pressing region at an end portion of the first pressing region is substantially equal to a gradient of the second pressing region of the first roller.

6. The extended film manufacturing apparatus according to any one of claims 1 to 3, wherein the first roller is a metal rigid roller or an elastic roller.

7. The extended film manufacturing apparatus according to any one of claims 1 to 3, wherein the first roller, the second roller, and the third roller contain a heat medium inside.

8. The extended film manufacturing apparatus according to any one of claims 1 to 3, wherein the first thermoplastic resin is an acrylic resin, and the second thermoplastic resin is a polycarbonate resin. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Images