JP7504605B2 - Stretched Film Manufacturing Equipment - Google Patents

Description

The present invention relates to a stretched film manufacturing device using a touch roll.

Thickness precision is important for films such as optical films, so they are generally formed using touch roll molding.

The film formed by the touch roll molding is then held at both ends by clips and stretched in the direction of movement (vertical direction) and width (horizontal direction). During this process, stress is concentrated at the ends of the film, causing tears and the risk of the film breaking.

Therefore, for example, the stretched film manufacturing device described in Patent Document 1 forms a multi-row end film using polycarbonate resin or the like as reinforcement at the end of the film being formed.

Patent No. 6377354 Japanese Patent Application Laid-Open No. 11-105131

However, because the state of bank (resin pool) formation differs between the end and center of the film at the contact area of the touch roll, wrinkles and rough areas occur at the end during the pressing process by the touch roll and the cooling and solidifying process. Stress is concentrated in these wrinkled and rough areas when the film is stretched, which causes breakage. For this reason, Patent Document 1 provides a trimming process (smoothing process) to remove uneven areas at both ends of the film before stretching the molded end multi-row film. However, there is a problem in that the trimming process is time-consuming and there is a risk of productivity decreasing due to breakage of the film caused by the trimming process.

In addition, in Patent Document 2, open molding is performed to mold the film without pressing it with a roll. However, there is a problem in that the thickness precision and surface smoothness of the film molded by open molding are inferior to the film molded with a touch roll.

The present invention has been made in consideration of the above, and aims to provide a stretched film manufacturing device that can manufacture stretched film with high thickness accuracy without breaking or wrinkling at the edges, even without a trimming process before stretching.

In order to solve the above-mentioned problems and achieve the object, a stretched film manufacturing apparatus according to the present invention includes an input section for inputting a molten first thermoplastic resin into a widthwise center portion and inputting a molten second thermoplastic resin onto both widthwise end sides of the first thermoplastic resin, a first pressing section for pressing the first thermoplastic resin and the second thermoplastic resin inputted from the input section in a first pressing region formed by a first roll and a second roll, and a second pressing section for pressing the second thermoplastic resin pressed by the first pressing section on both widthwise end sides of the first pressing section onto both ends of the first pressing region formed by the first roll and the second roll. the second pressing section pressing the first thermoplastic resin and the second thermoplastic resin with a pressing force lower than that of the first pressing section in a second pressing region to be formed ; a cooling section pressing the first thermoplastic resin and the second thermoplastic resin between the first roll and the second roll, and then cooling the first thermoplastic resin by passing the resin between a third roll arranged on the opposite side of the first roll across the second roll; and a stretching section gripping the second thermoplastic resin regions on both ends of a film formed of the first thermoplastic resin and the second thermoplastic resin cooled in the cooling section, and stretching the film in a moving direction and a width direction perpendicular to the moving direction.

The stretched film manufacturing apparatus according to the present invention has the advantage that it is possible to manufacture stretched films with high thickness accuracy without breakage or wrinkles at the edges, even without a trimming process before stretching.

1 is an overall schematic diagram of a stretched film production apparatus according to a first embodiment. FIG. FIG. 2 is a side view of a pressing device provided in the stretched film production apparatus according to the first embodiment. FIG. FIG. 4 is a top view of a pressing unit and a cooling unit of a stretched film production apparatus according to a modified example of the first embodiment. FIG. 13 is a top view of a pressing unit and a cooling unit of a stretched film production apparatus according to a modified example of the second embodiment. FIG. 13 is a top view of a pressing unit and a cooling unit of a stretched film production apparatus according to a modified example of the second embodiment.

Below, an embodiment of the stretched film manufacturing apparatus according to the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment. Furthermore, the components in the following embodiment include those that are replaceable and easily conceivable by a person skilled in the art, or those that are substantially the same.

First Embodiment
[Explanation of the schematic configuration of the stretched film manufacturing apparatus]
First, the overall configuration of a stretched film production apparatus 10 according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is an overall schematic diagram of the stretched film production apparatus according to the first embodiment.

The stretched film manufacturing apparatus 10 includes a pressing device 12 and a simultaneous biaxial stretching device 14. The stretched film manufacturing apparatus 10 may also include a sequential stretching device that sequentially stretches the film in the longitudinal and transverse directions. The following description will be given assuming that the apparatus includes a simultaneous biaxial stretching device 14.

The pressing device 12 includes a T-die 24, a touch roll 20a, a No. 2 roll 21, a No. 3 roll 22, and a transport roll 23.

The T-die 24 introduces the thermoplastic resin (hereinafter referred to as molten thermoplastic resin) melted by an extruder (not shown), which is the material for the film, between the touch roll 20a and the No. 2 roll 21, which are rotating with their roll surfaces in contact with each other. The T-die 24 is an example of an introduction section in this disclosure.

The touch roll 20a is a roll of a substantially cylindrical shape, and presses the molten thermoplastic resin introduced from the T-die 24 by sandwiching it between the touch roll 20a and the No. 2 roll 21. The touch roll 20a is driven to rotate by an electric motor 25a controlled by a control device (not shown). The touch roll 20a adjusts the pressing force with the No. 2 roll 21 by a pressing force adjuster 26, which is controlled by a control device (not shown) and includes a cylinder and a piston that are hydraulically controlled, for example. The touch roll 20a is an example of the first roll in this disclosure. The detailed shape of the touch roll 20a will be described later (see FIG. 4).

A heat transfer medium (hereafter referred to as heat transfer medium), such as cooling water or cooling oil, circulates inside the touch roll 20a, and the molten thermoplastic resin is cooled by being sandwiched between the touch roll 20a and the No. 2 roll 21 and pressed against it.

The No. 2 roll 21 is a cylindrical roll that presses the molten thermoplastic resin introduced from the T-die 24 by sandwiching it between the touch roll 20a and the No. 2 roll 21. The No. 2 roll 21 is driven to rotate by an electric motor 25b controlled by a control device (not shown). The No. 2 roll 21 is an example of the second roll in this disclosure.

A heat transfer medium such as cooling water or cooling oil circulates inside the No. 2 roll 21, and the molten thermoplastic resin is cooled by being sandwiched between the touch roll 20a and pressed against it.

The No. 3 roll 22 is a cylindrical roll in which a heat transfer medium such as cooling water or cooling oil circulates. The No. 3 roll 22 is disposed on the opposite side of the touch roll 20a across the No. 2 roll 21 (see FIG. 2). The No. 3 roll 22 cools the molten thermoplastic resin formed into a film shape by sandwiching it between the No. 2 roll 21 and the No. 3 roll 22. The No. 3 roll 22 is driven to rotate by an electric motor 25c controlled by a control device (not shown). The No. 3 roll 22 is an example of the third roll in this disclosure.

The transport roll 23 is a cylindrical roll that directs the direction of movement of the film S that has been pressed and cooled toward the entrance 1a of the simultaneous biaxial stretching device 14.

The simultaneous biaxial stretching device 14 has an endless loop 15R and an endless loop 15L symmetrically on the left and right sides in a plan view, each having a number of clips 30 for holding the film S. The film S to be stretched is fed from the entrance 1a and discharged from the exit 1b in a stretched state. The endless loop on the right side of the film S to be stretched as viewed from the entrance 1a side is called the right endless loop 15R, and the endless loop on the left side is called the left endless loop 15L. The film S is, for example, a resin film having thermoplasticity. For the following explanation, a coordinate system XYZ shown in FIG. 1 is set. The X axis is the axial direction of the touch roll 20a, the No. 2 roll 21, the No. 3 roll 22, and the transport roll 23, and the width direction of the film S. The Y axis is the movement direction of the film S in the simultaneous biaxial stretching device 14. The Z axis is a direction perpendicular to the X axis and the Y axis. The simultaneous biaxial stretching device 14 is an example of a stretching section in this disclosure.

The clips 30 are each attached to one end in the longitudinal direction of a rectangular clip carrying member 31 (at a position facing each other between the inlet 1a and the outlet 1b). That is, a pair of opposing clips 30 are arranged at both ends in the width direction of the film S, which is the object to be stretched, and function as a gripping device that grips the object to be stretched.

The clip carrying member 31 moves in a loop while being guided by the reference rail 40. The right endless loop 15R moves in a clockwise direction, and the left endless loop 15L moves in a counterclockwise direction. Specifically, the drive roller (not shown) of the clip carrying member 31 selectively engages with the drive sprockets 32 and 33 to run each clip carrying member 31 along the circular path. That is, the drive sprockets 32 and 33 selectively engage with the drive roller of each clip carrying member 31, and are driven to rotate by an electric motor to provide the clip carrying member 31 with a force to run each clip carrying member 31 along the circular path. Specifically, the two drive sprockets 33 are driven by the rotational drive force of the electric motor 34, which is decelerated by a reducer (not shown). The two drive sprockets 32 are each driven by the rotational drive force of an electric motor (not shown), which is decelerated in the opposite direction by two reducers (not shown).

When the distance between the reference rail 40 of the right endless loop 15R and the reference rail 40 of the left endless loop 10L increases, the film S is stretched in the horizontal direction (X-axis direction).

Adjacent clip carrying members 31 are connected to each other by a clip link mechanism 35 consisting of multiple links. The clip link mechanism 35 is guided by a pitch setting rail 41 and moves in a loop shape, accompanying the clip carrying members 31.

The clip link mechanism 35 sets the distance between adjacent clip carrying members 31 (hereafter referred to as the clip pitch) according to the distance between the reference rail 40 and the pitch setting rail 41. As the clip pitch increases, the film S is stretched in a direction perpendicular to the width direction, that is, in the vertical direction (Y-axis direction) which is the movement direction of the clip carrying members 31. Note that FIG. 1 shows how the film S fed from the entrance 1a is stretched in two axial directions, vertical and horizontal. To make the drawing easier to understand, the film S is drawn discontinuously, but in reality, the film S is continuous from the entrance 1a to the exit 1b.

The simultaneous biaxial stretching device 14 has, from the entrance 1a side of the film S to the exit 1b side, a preheating zone A, a stretching zone B, and a heat treatment zone C.

In preheating zone A, the distance (separation distance) between the reference rails 40 of the left endless loop 15L and the right endless loop 15R is set to the initial width of horizontal stretching, and the left endless loop 15L and the right endless loop 15R are arranged parallel to each other throughout the entire area. Note that in the left endless loop 15L and the right endless loop 15R, the distance between the reference rail 40 and the pitch setting rail 41 is equivalent to the initial pitch of vertical stretching.

In the stretching zone B, the distance between the left endless loop 15L and the right endless loop 15R is gradually increased from the preheating zone A side toward the heat treatment zone C, and the left endless loop 15L and the right endless loop 15R are arranged non-parallel. The distance between the left endless loop 15L and the right endless loop 15R in the stretching zone B is set to the initial width of the transverse stretch at the stretching start end (the end connected to the preheating zone A) and to the final width of the transverse stretch at the stretching end (the end connected to the heat treatment zone C). That is, in the stretching zone B, the distance between the reference rail 40 of the left endless loop 15L and the reference rail 40 of the right endless loop 15R is gradually increased from the preheating zone A side toward the heat treatment zone C. The distance between each reference rail 40 corresponds to the initial width of transverse stretching at the stretching start end (the end connecting to preheating zone A), and corresponds to the final width of transverse stretching at the stretching end (the end connecting to heat treatment zone C).

Furthermore, in the stretching zone B, the distance between the reference rail 40 and the pitch setting rail 41 in the left endless loop 15L is gradually reduced from the preheating zone A toward the heat treatment zone C. Similarly, the distance between the reference rail 40 and the pitch setting rail 41 in the right endless loop 15R is gradually reduced. The distance between the reference rail 40 and the pitch setting rail 41 is equivalent to the initial pitch of longitudinal stretching at the stretching start end (the end connected to the preheating zone A) and is equivalent to the final pitch of longitudinal stretching at the stretching end (the end connected to the heat treatment zone C). That is, the simultaneous biaxial stretching device 14 simultaneously performs longitudinal and transverse stretching on the film S in the stretching zone B.

In the heat treatment zone C, the distance between the left endless loop 15L and the right endless loop 15R is set to the final width of the horizontal stretching, and the left endless loop 15L and the right endless loop 15R are arranged parallel to each other throughout the entire area. In addition, the distance between the reference rail 40 and the pitch setting rail 41 is set to the final pitch of the vertical stretching, and the reference rail 40 and the pitch setting rail 41 are arranged parallel to each other throughout the entire area.

[Explanation of detailed configuration of pressing device]
Next, the detailed configuration of the pressing device 12 for pressing the molten thermoplastic resin will be described with reference to Figures 2 and 3. Figure 2 is a side view of the pressing device provided in the stretched film production apparatus according to the first embodiment. Figure 3 is a top view of the pressing section and the cooling section.

The molten thermoplastic resin 28 injected downward along the Z axis from the T-die 24 has a multi-row structure with acrylic resin 28a arranged in the center and polycarbonate resin 28b arranged at both ends, as shown in Figure 3.

The molten thermoplastic resin 28 that is introduced enters the contact surface between the touch roll 20a, which rotates clockwise (in the direction of the arrow K1 in FIG. 2) around the rotating shaft 27a, and the No. 2 roll 21, which rotates counterclockwise (in the direction of the arrow K2 in FIG. 2) around the rotating shaft 27b. The touch roll 20a is pressed toward the No. 2 roll 21 by the pressing force regulator 26, so that the molten thermoplastic resin 28 is sandwiched and pressed between the touch roll 20a and the No. 2 roll 21.

The molten thermoplastic resin 28 is cooled by the heat medium circulating inside the touch roll 20a and the heat medium circulating inside the No. 2 roll 21. These heat mediums are controlled to a temperature near the glass transition point of the molten thermoplastic resin 28. By setting the heat medium circulating inside the No. 2 roll 21 to a slightly higher temperature than the heat medium circulating inside the touch roll 20a, the molten thermoplastic resin 28 pressed by the touch roll 20a and the No. 2 roll 21 moves in the positive direction of the Y axis along the surface (roll surface) of the No. 2 roll 21, which has a higher temperature.

The molten thermoplastic resin 28 is then sandwiched between the No. 2 roll 21 and the No. 3 roll 22, which rotates clockwise (in the direction of arrow K3) around the rotation axis 27c, and cooled. Note that the heat medium circulating inside the No. 3 roll 22 is set to a higher temperature than the heat medium circulating inside the No. 2 roll 21, so the molten thermoplastic resin 28 (film S) sandwiched between the No. 2 roll 21 and the No. 3 roll 22 moves in the positive direction of the Y axis along the surface (roll surface) of the No. 3 roll 22, which has a higher temperature.

After going through each of the above steps, the film S is formed from the molten thermoplastic resin 28 that was introduced.

The stretched film manufacturing apparatus 10 in this embodiment manufactures a multi-row end film in which both widthwise ends of the film S are made of polycarbonate resin and the center portion in the widthwise direction is made of acrylic resin. In general, polycarbonate resin has greater strength than acrylic resin. Therefore, even when both widthwise ends of the molded film S made of polycarbonate resin are gripped by the clips 30 provided in the simultaneous biaxial stretching apparatus 14 and stretched in the moving direction and width direction of the film S, the film S can be stretched in the vertical and horizontal directions at a predetermined ratio without breaking.

[Explanation of the Function of the Pressing Device]
Next, the operation of the pressing device 12 will be described with reference to FIG. 3. The central roll surface 50a of the central part of the roll surface of the touch roll 20a is crowned. In general, when a roll is pressed, the pressing force may decrease due to the deflection of the roll itself. When it is desired to make the pressing force uniform, the central part of the roll is processed to be thicker than the end part of the roll. This is crown processing. The cross section including the rotation axis of the roll formed by crown processing exhibits a curved shape such as a quadratic curve, a quartic curve, or a sine curve called a crown curve. The central roll surface 50a is pressed against the No. 2 roll 21 having a cylindrical roll surface 21a to form a first pressing part 60. In this embodiment, a part of the acrylic resin 28a and the polycarbonate resin 28b is pressed against the central roll surface 50a of the touch roll 20a and the roll surface 21a of the No. 2 roll 21 in the first pressing part 60. The central roll surface 50a and the roll surface 21a facing the central roll surface 50a are an example of a first pressing region in the present disclosure.

Among the roll surfaces of the touch roll 20a, the end roll surfaces 50b, 50c on both ends are processed into a tapered shape in which the diameter of the touch roll 20a gradually decreases toward both ends of the touch roll 20a. The end roll surfaces 50b, 50c are pressed against the roll surface 21a of the No. 2 roll 21 to form second pressing portions 61 on both ends of the first pressing portion 60. In this embodiment, a part of the polycarbonate resin 28b is pressed against the end roll surfaces 50b, 50c of the touch roll 20a and the roll surface 21a of the No. 2 roll 21 with a pressing force lower than the pressing force in the first pressing portion 60 in the second pressing portion 61. Therefore, the thickness of the polycarbonate resin 28b in the second pressing portion 61 is formed to be thicker than the thicknesses of the acrylic resin 28a and the polycarbonate resin 28b pressed by the first pressing portion 60. For example, the film S is formed to be about 50 μm thicker in the second pressing portion 61 than the thickness of the film S formed by the first pressing portion 60. Note that the end roll surfaces 50b, 50c and the roll surface 21a facing the end roll surfaces 50b, 50c are an example of a second pressing region in the present disclosure.

Figure 3 shows an enlarged view of the central roll surface 50a and the end roll surface 50c of the touch roll 20a. The crowned central roll surface 50a has a tangent at the end of the central roll surface 50a with an inclination angle θ1. The tapered end roll surface 50c has an inclination angle θ2. The pressing device 12 processes the end roll surface 50c so that the angles θ2 and θ1 are approximately equal. By processing the end roll surface 50c so that θ1 ≒ θ2, the cross-sectional shape of the touch roll 20a can be approximated to that of a conventional crowned touch roll, and the pressing force in the width direction of the touch roll 20a can be made uniform.

The molten thermoplastic resin 28 pressed by the touch roll 20a and the No. 2 roll 21 is then cooled by passing through a cooling section 62 formed by the roll surface 21a of the No. 2 roll 21 and the roll surface 22a of the No. 3 roll 22. Here, in order to cool the molten thermoplastic resin 28, the molten thermoplastic resin 28 may be brought into contact with the roll surface 21a of the No. 2 roll 21 and the roll surface 22a of the No. 3 roll 22, or may simply be passed between the roll surfaces 21a and 22a. It is preferable that both the roll surface 21a of the No. 2 roll 21 and the roll surface 22a of the No. 3 roll 22 are cylindrical surfaces.

The molten thermoplastic resin 28 cooled by the roll surface 21a of the No. 2 roll 21 and the roll surface 22a of the No. 3 roll 22 is discharged as a film S from the No. 3 roll 22. As shown in FIG. 3, the film S has an area Sa pressed by the first pressing part 60 with a high pressing force and areas Sb and Sc pressed by the second pressing part 61 with a low pressing force. In the present embodiment, the area Sa is formed of the acrylic resin 28a and the polycarbonate resin 28b, and the areas Sb and Sc are formed of the polycarbonate resin 28b. The film S is then guided by the transport roll 23 (see FIG. 2) and fed into the inlet 1a of the simultaneous biaxial stretching device 14.

The film S fed into the simultaneous biaxial stretching device 14 is stretched in the moving direction (Y direction) and the width direction while the regions at both ends in the width direction (X-axis direction) formed by the polycarbonate resin 28 b are held by clips 30 (see FIG. 1 ).

From the viewpoint of surface smoothness and thickness uniformity, the touch roll 20a is preferably a rigid metal roll. A high-hardness coating is formed on the central roll surface 50a and the end roll surfaces 50b and 50c by HCr (hard chrome plating). The touch roll 20a may also be an elastic roll such as an elastic metal roll.

In addition, in FIG. 3, an example was described in which both ends of the roll surface of the touch roll 20a were tapered and the center of the roll surface of the touch roll 20a was crowned, but the same effect can be obtained by forming the touch roll 20a into a cylindrical shape and forming the No. 2 roll 21 into the same shape as the touch roll 20a in FIG. 3. However, if the No. 2 roll 21 is tapered, the adhesion between the No. 2 roll 21 and the No. 3 roll 22 decreases, so there is a possibility that the cooling performance of the molten thermoplastic resin 28 decreases. Therefore, it is preferable to perform the tapering on the touch roll 20a side. In addition, since the No. 2 roll 21 cannot be removed, a roll cleaning device is attached and cleaned. If the No. 2 roll 21 is tapered, the contact of the cleaner is weak when the roll cleaning device is attached, and there is a risk of leaving some parts unwiped or wiping being uneven, so it is preferable that the No. 2 roll 21 is flat across the width.

As described above, in the stretched film manufacturing apparatus 10, the first pressing section 60 formed by the central roll surface 50a (first pressing area) of the touch roll 20a (first roll) and the roll surface 21a (first pressing area) of the No. 2 roll 21 (second roll) presses the acrylic resin 28a (first thermoplastic resin) introduced from the T die 24 (input section) with a high pressing force. The second pressing section 61 formed by the end roll surfaces 50b, 50c (second pressing area) of the touch roll 20a (first roll) and the roll surface 21a (second pressing area) of the No. 2 roll 21 (second roll) presses the polycarbonate resin 28b (second thermoplastic resin) introduced from the T die 24 (input section) to both ends of the width direction of the acrylic resin 28a with a pressing force lower than that of the first pressing area. Furthermore, the cooling section 62 cools the acrylic resin 28a and the polycarbonate resin 28b by sandwiching them between the No. 2 roll 21 (second roll) and the No. 3 roll 22 (third roll). The simultaneous biaxial stretching device 14 (stretching section) grips the polycarbonate resin 28b regions at both ends of the film S formed of the acrylic resin 28a and the polycarbonate resin 28b cooled in the cooling section 62, and stretches the film S in the moving direction and the width direction perpendicular to the moving direction. Therefore, since no part is formed where stress is concentrated when the film S is stretched, there is no need to provide a trimming process before stretching. In addition, since the end of the thermoplastic resin is pressed with low pressure, the occurrence of wrinkles is suppressed, and since the polycarbonate resin 28b at the end of the film S has a greater strength than the acrylic resin 28a, it does not break during stretching. Therefore, a stretched film with high thickness accuracy can be manufactured. In addition, since the trimming process is no longer necessary, the equipment can be made more compact and the process of disposing of the film removed in the trimming process is also no longer necessary. Furthermore, the amount of polycarbonate resin 28b used to mold the end portion is kept to a minimum, improving yields.

In addition, in the stretched film manufacturing apparatus 10, the end roll surfaces 50b, 50c (second pressing regions) of the touch roll 20a (first roll) are formed so that the diameter of the touch roll 20a gradually decreases toward both ends. Therefore, the molten thermoplastic resin 28 introduced is pressed in the second pressing region with a lower pressing force than in the first pressing region. This allows both ends of the film S to be formed thicker than the center.

In addition, in the stretched film manufacturing apparatus 10, the first pressing section 60 of the touch roll 20a (first roll) is crowned. Therefore, the first pressing section 60 can reliably press the touch roll 20a against the No. 2 roll 21 (second roll).

In addition, in the stretched film manufacturing apparatus 10, when the touch roll 20a (first roll) is cut along a plane including the roll axis of the touch roll 20a, the inclination of the tangent to the central roll surface 50a (first pressing region) at the end of the central roll surface 50a is approximately equal to the inclination of the end roll surfaces 50b, 50c (second pressing region) of the touch roll 20a. Therefore, the cross-sectional shape can be approximated to that of a conventional touch roll that has been crowned, making it possible to uniform the pressing force in the width direction of the touch roll 20a.

In addition, in the stretched film manufacturing apparatus 10, the touch roll 20a (first roll) is a rigid metal roll or an elastic roll. Therefore, the molten thermoplastic resin 28 can be reliably pressed in the first pressing section 60.

In addition, in the stretched film manufacturing apparatus 10, the touch roll 20a (first roll), the No. 2 roll 21 (second roll), and the No. 3 roll 22 (third roll) contain a heat medium inside. Therefore, the molten thermoplastic resin 28 that is introduced can be cooled reliably.

In addition, 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, the end of the film S can be reinforced without causing wrinkles or rough areas.

[Modification of the first embodiment]
Next, a modified example of the first embodiment will be described with reference to Fig. 4. Fig. 4 is a top view of a pressing section and a cooling section of a stretched film production apparatus according to a modified example of the first embodiment.

This embodiment is an example in which a touch roll 20b is used instead of the touch roll 20a in the first embodiment. The central roll surface 50d (first pressing area) of the touch roll 20b is not crowned and forms a cylindrical surface.

The touch roll 20b is pressed against the No. 2 roll 21 to form a film S from the molten thermoplastic resin 28 that has been introduced. At that time, the acrylic resin 28a and part of the polycarbonate resin 28b in the center are pressed with a high pressing force, and the polycarbonate resin 28b at both ends is pressed with a low pressing force. Therefore, as in the first embodiment, the polycarbonate resin 28b at both ends is formed thicker than the acrylic resin 28a in the center.

Second Embodiment
Next, a second embodiment of the present disclosure will be described with reference to Fig. 5. Fig. 5 is a top view of a pressing unit and a cooling unit of a stretched film production apparatus according to a modified example of the second embodiment.

This embodiment is an example in which a touch roll 20c is used instead of the touch roll 20a in the first embodiment. The touch roll 20c has end roll surfaces 50e and 50f instead of the end roll surfaces 50b and 50c (see FIG. 3). The end roll surfaces 50e and 50f form cylindrical surfaces with a smaller diameter than the crowned central roll surface 50a. That is, a step is formed between the central roll surface 50a and the end roll surfaces 50e and 50f.

When the touch roll 20c is pressed against the No. 2 roll 21, the central roll surface 50a of the touch roll 20c is pressed against the roll surface 21a of the No. 2 roll 21 to form a first pressing portion 60. In addition, the end roll surfaces 50b and 50c of the touch roll 20c are pressed against the roll surface 21a of the No. 2 roll 21 to form a second pressing portion 61.

At this time, the first pressing portion 60 is pressed with a high pressing force, and the second pressing portion 61 is pressed with a low pressing force. Therefore, the portions of the polycarbonate resin 28b at both ends of the molten thermoplastic resin 28 (areas Sb and Sc) are molded thicker than the acrylic resin 28a and the portion of the polycarbonate resin 28b at the center (area Sa).

[Modification of the second embodiment]
Next, a modified example of the second embodiment will be described with reference to Fig. 6. Fig. 6 is a top view of a pressing section and a cooling section of a stretched film production apparatus according to a modified example of the second embodiment.

This embodiment is an example in which a touch roll 20d is used instead of the touch roll 20c in the second embodiment. The central roll surface 50d (first pressing area) of the touch roll 20d is not crowned and forms a cylindrical surface.

The touch roll 20d is pressed against the No. 2 roll 21 to form a film S from the molten thermoplastic resin 28. At that time, the acrylic resin 28a and part of the polycarbonate resin 28b in the center (area Sa) are pressed with a high pressing force, and the part of the polycarbonate resin 28b at both ends (areas Sb, Sc) are pressed with a low pressing force. Therefore, as in the second embodiment, the part of the polycarbonate resin 28b at both ends is formed thicker than the part of the acrylic resin 28a and part of the polycarbonate resin 28b in the center.

As described above, in the stretched film manufacturing apparatus 10, the end roll surfaces 50e, 50f (second pressing area) of the touch roll 20c (first roll) are formed as cylindrical surfaces with a smaller diameter than the central roll surface 50a (first pressing area) of the touch roll 20c. Therefore, the molten thermoplastic resin 28 introduced is pressed in the second pressing area with a lower pressing force than in the first pressing area. This allows both ends of the film S to be formed thicker than the center.

10... Stretched film manufacturing apparatus, 12... Pressing device (first pressing section, second pressing section, cooling section), 14... Simultaneous biaxial stretching apparatus (stretching section), 15L... Left endless loop, 15R... Right endless loop, 20a, 20b, 20c, 20d... Touch rolls (first roll), 21... No. 2 roll (second roll), 21a... Roll surface (first pressing area, second pressing area), 22... No. 3 roll (third roll), 22a...roll surface, 23...transport roll, 24...T-die (feeding section), 25a, 25b, 25c...electric motor, 28...molten thermoplastic resin, 28a...acrylic resin (first thermoplastic resin), 28b ... polycarbonate resin (second thermoplastic resin), 30...clip, 31...clip support member, 35...clip link mechanism, 40...reference rail, 41...pitch setting rail, 50a, 50d...central roll surface (first pressing area), 50b, 50c, 50e, 50f...end roll surface (second pressing area), 60...first pressing section, 61...second pressing section, 62...cooling section, A...preheating zone, B...stretching zone, C...heat treatment zone, S...film, Sa, Sb, Sc...areas

Claims (8)

an input section for inputting a molten first thermoplastic resin into a widthwise center section and inputting a molten second thermoplastic resin into both widthwise end sides of the first thermoplastic resin;
a first pressing section that presses the first thermoplastic resin and the second thermoplastic resin input from the input section in a first pressing region formed by a first roll and a second roll;
a second pressing section that presses the second thermoplastic resin at both ends of the width direction of the first pressing section, of the second thermoplastic resin pressed by the first pressing section , in a second pressing section formed at both ends of the first pressing section by the first roll and the second roll, with a pressing force lower than that of the first pressing section;
a cooling section that presses the first thermoplastic resin and the second thermoplastic resin between the first roll and the second roll, and then cools the resin by passing the resin between a third roll disposed on the opposite side of the first roll across the second roll;
a stretching section that grips the second thermoplastic resin regions at both ends of a film formed of the first thermoplastic resin and the second thermoplastic resin cooled in the cooling section and stretches the film in a moving direction and a width direction perpendicular to the moving direction;
A stretched film manufacturing apparatus comprising: The second pressing region of the first roll is formed such that the diameter of the first roll gradually decreases toward both ends.
The stretched film manufacturing apparatus according to claim 1 . The second pressing area of the first roll is formed by a cylindrical surface having a smaller diameter than the first pressing area of the first roll.
The stretched film manufacturing apparatus according to claim 1 . The first pressing area of the first roll is crowned.
The stretched film manufacturing apparatus according to claim 2 or 3. When the first roll is cut along a plane including a roll axis of the first roll, a slope of a tangent to the first pressing region at an end of the first pressing region is substantially equal to a slope of the second pressing region of the first roll.
The stretched film manufacturing apparatus according to claim 2 . The first roll is a rigid metal roll or an elastic roll.
The stretched film manufacturing apparatus according to any one of claims 1 to 5. The first roll, the second roll, and the third roll each contain a heat medium therein.
The stretched film manufacturing apparatus according to any one of claims 1 to 6. the first thermoplastic resin is an acrylic resin;
The second thermoplastic resin is a polycarbonate resin.
The stretched film manufacturing apparatus according to any one of claims 1 to 7.

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