JP7657247B2 - Manufacturing method of end film roll - Google Patents

Description

The present invention relates to a method for manufacturing end film rolls.

Stretched films, which are widely used in various industrial products, are manufactured by stretching a resin film. For example, a method for manufacturing a stretched film has been proposed in which a long resin film is stretched in a direction intersecting the long direction while both ends in the width direction of the film are held by clips (see, for example, Patent Document 1). In such a method for manufacturing a stretched film, clip marks are left on both ends in the width direction of the stretched film. Therefore, the ends including the marks are generally cut off from the stretched film and discarded.
In recent years, from the viewpoint of reducing the environmental load, it is desired to reuse waste generated during the manufacture of various industrial products. Therefore, in the method for manufacturing a stretched film described in Patent Document 1, it has been considered to recover the end portion cut from the stretched film as an end film and to use it effectively. However, when the end film is wound up and recovered, the end film may break, making it difficult to recover the end film smoothly.

Patent No. 7096940

The present invention has been made to solve the above-mentioned problems of the conventional art, and its main objective is to provide a method for manufacturing end film rolls that can prevent the end film from breaking when the end film is wound up and can smoothly manufacture end film rolls.

[1] A method for producing an end film roll according to an embodiment of the present invention includes the steps of: preparing a stretched film by stretching a long resin film in a direction intersecting the long direction while holding both ends in the width direction of the film with clips; cutting both ends including the gripping marks of the clips from the stretched film to obtain an end film including the gripping marks; and winding up the end film with a winding member. The end film has, in the width direction, a first end where the gripping marks are located and a second end opposite to the first end. In the step of winding up the end film with the winding member, the second end is in contact with the winding member, and the first end is located away from the winding member.
[2] In the manufacturing method of an end film roll described in [1] above, the winding member may include a shaft and a roller portion. The roller portion is provided on the shaft. The roller portion has a larger diameter than the shaft. In the step of winding up the end film by the winding member, the second end may be in contact with the roller portion, and the first end may face the shaft with a gap therebetween.
[3] In the manufacturing method of an end film roll described in [1] above, the winding member may have a tapered surface that becomes smaller in diameter from one end toward the other end in the axial direction. In a step in which the winding member winds up the end film, the second end may contact the tapered surface, and the first end may face, with a gap therebetween, a portion of the tapered surface that has a smaller diameter than the contact portion of the second end.

According to an embodiment of the present invention, it is possible to prevent the end film from breaking when the end film is wound up, and end film rolls can be manufactured smoothly.

FIG. 1 is a schematic diagram for explaining a method for manufacturing an end film roll according to one embodiment of the present invention. FIG. 2 is a plan view of the stretched film of FIG. FIG. 3 is a schematic plan view for explaining a process in which the winding member in FIG. 1 winds up the end film. FIG. 4 is a schematic cross-sectional view for illustrating a process in which the winding member of FIG. 1 winds up the end film. FIG. 5 is a schematic cross-sectional view for explaining a method for manufacturing an end film roll according to another embodiment of the present invention.

The following describes embodiments of the present invention, but the present invention is not limited to these embodiments. In addition, in order to make the description clearer, the drawings may show the width, thickness, shape, etc. of each part more diagrammatically than the embodiments, but these are merely examples and do not limit the interpretation of the present invention.

(Definition of terms and symbols)
The definitions of terms and symbols used in this specification are as follows.
(1) Refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
"Re(λ)" is the in-plane retardation measured with light having a wavelength of λ nm at 23° C. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23° C. Re(λ) is calculated by the formula: Re(λ)=(nx−ny)×d, where d (nm) is the thickness of the layer (film).
(3) Angles When angles are referred to in this specification, unless otherwise specified, the angles include angles in both clockwise and counterclockwise directions.

A. Overview of the Manufacturing Method of an End Film Roll Fig. 1 is a schematic diagram for explaining a manufacturing method of an end film roll according to one embodiment of the present invention; Fig. 2 is a plan view of the stretched film in Fig. 1; Fig. 3 is a schematic plan view for explaining the process in which the winding member in Fig. 1 winds up the end film; and Fig. 4 is a schematic cross-sectional view for explaining the process in which the winding member in Fig. 1 winds up the end film.

The manufacturing method of the end film roll according to the embodiment of the present invention includes a stretching step, a cutting step, and a first winding step in this order (see FIG. 1). In the stretching step, the resin film 1 is stretched in a direction intersecting the longitudinal direction while each of both ends in the width direction of the long resin film 1 is held by a clip, to prepare a stretched film 2. In the cutting step, each of both ends including the gripping marks 3 of the clip is cut from the stretched film 2 to obtain an end film 4 including the gripping marks 3. In the first winding step, the winding member 5 winds up the end film 4. The end film 4 has a first end E1 where the gripping marks 3 of the clip are located in the width direction; and a second end E2 opposite to the first end E1 (see FIG. 3). In the first winding step, the second end E2 of the end film 4 is in contact with the winding member 5, and the first end E1 of the end film 4 is located away from the winding member 5 (see FIG. 4).
The inventors of the present invention have found that when the end film is wound and collected, the gripping marks of the clip become the starting point of cracks and cause the end film to break. As a result of extensive research into the winding means of the end film, the inventors have found that the end film can be stably wound up if the gripping marks of the clip are not in contact with the winding member. Specifically, the winding member 5 winds up the end film 4 in a state in which the second end E2 of the end film 4 is in contact with the winding member 5 and the first end E1 of the end film 4 (i.e., the gripping marks 3 of the clip) is away from the winding member 5, so that the breakage of the end film 4 can be suppressed and the end film 4 can be stably wound up. As a result, the end film roll 100 in which the end film 4 is wound around the winding member 5 can be smoothly manufactured. In other words, the end film 4 can be smoothly wound and collected in a roll shape. In other words, the manufacturing method of the end film roll according to the embodiment of the present invention is, in other words, a method for collecting the end film.

The collected end films (end film rolls) are independently distributable products and can be used industrially, typically as recycled resin raw materials.
The recycled resin raw material can be used to manufacture any suitable resin product. Examples of the resin product include optical films such as retardation films; packaging materials made of thermoplastic resins such as polyethylene terephthalate (PET) and nylon; and the like. Among these resin products, optical films are preferred, and retardation films are more preferred. In other words, the recovered end film can be suitably used as a raw material for optical films (typically retardation films).

Below, we will explain each step of the manufacturing method for the end film roll in detail.

B. Stretching Step As shown in FIG. 1, in the stretching step, a long resin film 1 is stretched, typically by a stretching device 7.

B-1. Resin film to be stretched In this specification, the resin film 1 refers to a film before the stretching process. Any appropriate film may be adopted as the resin film 1. As described above, the resin film 1 has a long shape. Any appropriate value may be adopted as the dimension in each direction of the resin film 1. The width of the resin film 1 (the dimension in the direction perpendicular to the long direction) is, for example, 500 mm or more, preferably 700 mm or more, and, for example, 2500 mm or less, preferably 2000 mm or less. The thickness of the resin film 1 is, for example, 40 μm or more, preferably 60 μm or more, and, for example, 200 μm or less, preferably 180 μm or less.

Examples of resin materials constituting the resin film 1 include polycarbonate-based resins, polyvinyl acetal-based resins, cycloolefin-based resins, (meth)acrylic-based resins, cellulose ester-based resins, cellulose-based resins, polyester-based resins, polyester carbonate-based resins, olefin-based resins, and polyurethane-based resins. Note that (meth)acrylic-based resins refer to acrylic-based resins and/or methacrylic-based resins. These resin materials can be used alone or in combination.

Among the resin materials constituting the resin film 1, polycarbonate (PC)-based resins, cycloolefin (COP)-based resins, (meth)acrylic-based resins, and polyester-based resins (typically polyethylene terephthalate (PET)) are preferred, and PC-based resins are more preferred. When such resin materials are used, the end film can be more stably recovered in the first winding process.

Examples of PC-based resins include PC-based resins that contain structural units derived from dihydroxy compounds. Specific examples of the dihydroxy compound include 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9,9-bis(4-hydroxy-3-ethylphenyl)fluorene, 9,9-bis(4-hydroxy-3-n-propylphenyl)fluorene, 9,9-bis(4-hydroxy-3-isopropylphenyl)fluorene, 9,9-bis(4-hydroxy-3-n-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-sec-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-tert-butylphenyl)fluorene, 9,9-bis(4-hydroxy-3-cyclohexylphenyl)fluorene, 9,9-bis(4-hydroxy-3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, and 9,9-bis( 4-(2-hydroxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isopropylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isobutylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-cyclohexyl phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3,5-dimethylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-6-methylphenyl)fluorene, 9,9-bis(4-(3-hydroxy-2,2-dimethylpropoxy)phenyl)fluorene. In addition to the structural units derived from the dihydroxy compounds, the PC resin may contain structural units derived from dihydroxy compounds such as isosorbide, isomannide, isoidet, spiroglycol, dioxane glycol, diethylene glycol (DEG), triethylene glycol (TEG), polyethylene glycol (PEG), cyclohexane dimethanol (CHDM), tricyclodecane dimethanol (TCDDM), and bisphenols.

Details of the above-mentioned PC-based resins are described, for example, in JP 2012-67300 A and Japanese Patent No. 3325560. The descriptions in these patent documents are incorporated herein by reference.

B-2. Stretching Device In one embodiment, the resin film 1 is transported in the longitudinal direction so as to pass through the stretching device 7. Therefore, the resin film 1 can be stretched while being transported, and the stretched film 2 can be continuously prepared.

Although not shown, the stretching device 7 is equipped with clips capable of gripping the widthwise ends of the resin film 1. The stretching device 7 is typically a tenter stretching device. The stretching device 7 stretches the resin film 1 in a direction intersecting with the longitudinal direction while each of the widthwise ends of the resin film 1 is gripped (typically clamped) by a clip. The stretching direction may be a direction substantially perpendicular to the longitudinal direction of the resin film 1 (for example, 90°±1° with respect to the longitudinal direction), or may be a direction intersecting both the longitudinal direction and the width direction of the resin film 1.

Details of the stretching process are described, for example, in Japanese Patent No. 7096940, Japanese Unexamined Patent Publication No. 2004-226686, and International Publication No. 2007/111313. The descriptions in these patent documents are incorporated herein by reference.

As a result, a long stretched film 2 is prepared as shown in FIG. 2. The stretching ratio in the width direction in the stretching process (width of stretched film/width of resin film) is, for example, 1.1 or more, preferably 1.5 or more, and, for example, 6.0 or less, preferably 4.0 or less.

Clip marks 3 are formed on both ends of the stretched film 2 in the width direction. The clip marks 3 are harder and more brittle than the rest of the stretched film 2.

The stretched film 2 typically has a slow axis in the stretching direction described above. The slow axis of the stretched film 2 may be misaligned in the width direction. More specifically, the direction of the slow axis of the stretched film 2 is likely to deviate from the desired angle at the width direction ends. Typically, the axis misalignment is not substantially manifested in the width direction center of the stretched film 2, and becomes larger as it approaches the width direction ends. In the stretched film 2 shown in the figure, the slow axis is substantially parallel to the stretching direction described above at the width direction center (for example, the axis misalignment is less than 0°±1°). In addition, at the width direction ends of the stretched film 2, the slow axis may cross the stretching direction described above (for example, the axis misalignment is 1° to 3°).

C. Cutting Step As shown in Fig. 1, in the cutting step, both ends including the grip marks 3 of the clip are cut from the stretched film 2, typically by a cutting device 8. In one embodiment, the stretched film 2 is transported in the longitudinal direction so as to pass through the cutting device 8. This allows the stretched film 2 to be cut continuously. The stretched film 2 is preferably subjected to the cutting step without coming into contact with a roller member such as a transport roller.

The cutting device 8 may have any suitable configuration. In the illustrated example, the cutting device 8 includes a gear cutter 81 and an opposing roller 82. The gear cutter 81 and the opposing roller 82 face each other. Each of the gear cutter 81 and the opposing roller 82 is rotatable. The gear cutter 81 can form a cutting line 21 in the stretched film 2 passing between the gear cutter 81 and the opposing roller 82 (see FIG. 2).

As shown in FIG. 2, the cutting device 8 typically forms two cutting lines 21 in the stretched film 2. The cutting lines 21 extend along the longitudinal direction of the stretched film 2. The two cutting lines 21 are formed at a predetermined distance from each other in the width direction of the stretched film 2, and each of the two cutting lines 21 is formed at a predetermined distance from the gripping mark 3 of the clip in the width direction of the stretched film 2.

Through the above steps, two end films 4 are obtained from the stretched film 2, which correspond to both ends of the stretched film 2 in the width direction. Each of the two end films 4 includes a clip gripping mark 3. Furthermore, the stretched film 2 from which the two end films 4 have been cut is configured as a product film 6. That is, in the cutting process, the stretched film 2 is typically separated into two end films 4 and the product film 6. Each of the two end films 4 and the product film 6 has an elongated shape.

The width of the end film 4 is not particularly limited as long as the end film 4 includes the entire gripping mark 3 of the clip. When the width of the stretched film 2 is taken as 100%, the width of the end film 4 is, for example, 0.5% or more, preferably 1.0% or more, more preferably 5.0% or more, and even more preferably 10.0% or more, and for example, 30% or less, preferably 25% or less, and more preferably 20% or less. The width of the end film 4 is, for example, 10 mm or more, preferably 20 mm or more, more preferably 100 mm or more, and even more preferably 200 mm or more, and for example, 600 mm or less, preferably 500 mm or less, and more preferably 300 mm or less.
When the width of the end film is equal to or greater than the lower limit, the end film can stably include the entire gripping mark of the clip, and the portion of the stretched film with the relatively large axial misalignment can be included in the end film. As a result, the gripping mark of the clip can be prevented from remaining on the product film, and the axial misalignment of the product film can be reduced. When the width of the end film is equal to or less than the upper limit, the yield of the product film can be improved.

The area ratio of the grip marks 3 of the clip to the end film 4 is, for example, 1% or more, preferably 5% or more, and, for example, 95% or less, preferably 75% or less.
When the area ratio of the grip marks is within the above range, the portion of the stretched film where the axial misalignment is relatively large can be sufficiently included in the end film, so that the axial misalignment of the product film can be stably reduced.

D. First Winding Step As shown in Fig. 1, in the first winding step, a winding member 5 winds up the end film 4 cut from the stretched film 2 by a cutting device 8. This allows the end film 4 to be continuously collected, and an end film roll 100 can be manufactured. The winding member 5 is typically rotatable about an axis that is substantially parallel to the width direction of the end film 4. Note that, for convenience, one winding member 5 is shown in Fig. 1, but in reality, the same number of winding members 5 as the number of end films 4 (i.e., two) are provided.

As shown in FIG. 3, the end film 4 has, in the width direction, a first end E1 where the gripping mark 3 of the clip is located, and a second end E2 opposite to the first end E1.
In the first winding step, the end film 4 is wound onto the winding member 5 in a state in which at least the second end E2 of the end film 4 is in contact with the winding member 5 and the first end E1 of the end film 4 (i.e., the gripping mark 3) is separated from the winding member 5. As the winding proceeds, the end film 4 is collected while being stacked in the radial direction of the winding member (see FIG. 4).

The width of the contact portion of the end film 4 with the winding member 5 is, when the width of the end film 4 is taken as 100%, for example, 30% or more, preferably 50% or more, and for example, 95% or less, preferably 80% or less. If the width of the contact portion of the end film is equal to or greater than the above-mentioned lower limit, the winding member can stably wind up the end film. If the width of the contact portion of the end film is equal to or less than the above-mentioned upper limit, the gripping mark of the clip can be stably prevented from coming into contact with the winding member.

The conveying speed (line speed) of the end film 4 from the cutting device 8 toward the winding member 5 is, for example, 50 mm/s or more, preferably 80 mm/s or more, and, for example, 1600 mm/s or less, preferably 1150 mm/s or less. When the line speed of the end film is in the above range, the tension applied to the end film can be adjusted to a suitable range, and breakage of the end film can be further suppressed.

D-1. Winding member The winding member 5 may have any suitable configuration. As shown in Fig. 4, in one embodiment, the winding member 5 includes a shaft 51 and a roller portion 52. Hereinafter, the winding member 5 including the shaft 51 and the roller portion 52 may be referred to as a step-down roller.

The shaft 51 typically has a cylindrical shape.
The roller portion 52 is provided on the shaft 51. In the illustrated example, the roller portion 52 is provided on the circumferential surface of the shaft 51 so as to expose both ends of the shaft 51. The roller portion 52 typically has a cylindrical shape. The roller portion 52 has a larger diameter than the shaft 51.

The outer diameter of the roller portion 52 is, for example, 50 mm or more and 200 mm or less. Examples of the material for the roller portion 52 include a material that is easy to process, and more specifically, examples of the material include acrylonitrile-butadiene-styrene copolymer synthetic resin (ABS) and fiber reinforced plastic (FRP).
In the illustrated example, the shaft 51 and the roller portion 52 are configured as separate bodies, but the shaft 51 and the roller portion 52 may also be configured as an integral body.

In this embodiment, in the first winding process, at least the second end E2 of the end film 4 contacts the outer peripheral surface of the roller portion 52, and the first end E1 of the end film 4 (i.e., the gripping mark 3) is located away from the roller portion 52 and faces the shaft 51 with a gap between them.

As shown in FIG. 5, in another embodiment, the winding member 5 has a tapered surface 53 that becomes smaller in diameter from one end to the other end in the axial direction. Hereinafter, the winding member 5 having the tapered surface 53 may be referred to as a tapered roller.

The tapered roller 5 typically has a truncated cone shape. The maximum outer diameter of the tapered roller 5 is, for example, 70 mm or more and 200 mm or less, and the minimum outer diameter is, for example, 40 mm or more and 100 mm or less. Examples of materials for the tapered roller 5 include ABS and FRP.
The taper angle of the tapered surface 53 is, for example, 15° or more, preferably 20° or more, more preferably 30° or more, and is, for example, 60° or less, preferably 50° or less, more preferably 45° or less. When the taper angle is in the above range, contact of the gripping mark of the clip with the tapered roller in the first winding step can be stably suppressed.

In this embodiment, in the first winding process, at least the second end E2 of the end film 4 contacts the tapered surface 53, and the first end E1 of the end film 4 (i.e., the gripping mark 3) faces a portion of the tapered surface 53 that is smaller in diameter than the contact portion of the second end E2, with a gap therebetween.

E. Second Winding Step As shown in Figure 1, the product film 6 obtained in the cutting step described above is collected by any suitable means. In one embodiment, the manufacturing method for an end film roll further includes a second winding step in which a winding member 9 winds up the product film 6. In the second winding step, the product film 6 is wound around the winding member 9 and collected. This makes it possible to manufacture a product film roll 101 in which the product film 6 is wound in a roll shape. The winding member 9 may have any suitable configuration.

The product film 6 is typically configured as a retardation film having a slow axis. The refractive index of the product film 6 satisfies the relationship nx>ny.
In one embodiment, the product film 6 functions as a λ/4 plate. When the product film functions as a λ/4 plate, the in-plane retardation Re(550) of the product film 6 is, for example, 100 nm to 180 nm, and preferably 135 nm to 155 nm.
In another embodiment, the retardation film functions as a λ/2 plate. When the product film functions as a λ/2 plate, the in-plane retardation Re(550) of the product film 6 is, for example, 230 nm to 310 nm, preferably 250 nm to 290 nm.

The wavelength dependence of the product film 6 is not particularly limited. The product film 6 preferably exhibits wavelength dependence of reverse dispersion. The Re(450)/Re(550) of the product film 6 is preferably 0.8 or more and less than 1.0, more preferably 0.8 to 0.95. The Re(550)/Re(650) of the product film 6 is preferably 0.8 or more and less than 1.0, more preferably 0.8 to 0.97.

The absolute value of the photoelastic coefficient of the product film 6 is, for example, 2×10 ⁻¹² (m ² /N) to 100×10 ⁻¹² (m ² /N), and preferably 5×10 ⁻¹² (m ² /N) to 50×10 ⁻¹² (m ² /N).

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring each property are as follows. Note that "parts" and "%" in the examples and comparative examples are based on mass unless otherwise specified.

<<Preparation of Stretched Film>>
<Preparation Example 1>
In the same manner as in Production Example 9 of JP 2022-150732 A, a resin film made of a PC resin was prepared, and the resin film was stretched to prepare a stretched film made of a PC resin. The width of the stretched film was 2000 mm. The thickness of the stretched film was 48 μm. A clip grip mark was formed on each of both ends in the width direction of the stretched film.

<Preparation Example 2>
A stretched film made of PET was prepared in the same manner as in Production Example 9 of JP-A-2022-150732, except that the resin film made of PC resin was changed to a resin film made of PET (manufactured by Toray Industries, Inc., product number "50U48"). The width of the stretched film was 2000 mm. The thickness of the stretched film was 50 μm. A clip grip mark was formed on each of both ends in the width direction of the stretched film.

<Preparation Example 3>
A stretched film made of an acrylic resin was prepared in the same manner as in Production Example 9 of JP-A-2022-150732, except that the resin film made of a PC resin was changed to a resin film made of an acrylic resin (manufactured by Kaneka Corporation, product name "HTX-Z"). The width of the stretched film was 2000 mm. The thickness of the stretched film was 40 μm. A clip grip mark was formed on each of both ends in the width direction of the stretched film.

<Preparation Example 4>
A stretched film made of a COP resin was prepared in the same manner as in Production Example 9 of JP-A-2022-150732, except that the resin film made of a PC resin was changed to a resin film made of a COP resin (manufactured by Zeon Corporation, product number "ZF16"). The width of the stretched film was 2000 mm. The thickness of the stretched film was 40 μm. A clip grip mark was formed on each of both ends in the width direction of the stretched film.

[Example 1]
The stretched film made of PC resin obtained in Preparation Example 1 was cut by a slitter (cutting device) to separate it into two end films and a product film. The width of each of the two end films was 250 mm (12.5% when the width of the stretched film was 100%). The width of the product film was 1500 mm.

Next, the step-down roller shown in Figures 3 and 4 was prepared. The roller part was made of ABS. The outer diameter of the roller part was 92.5 mm. In Table 1, the taper angle is the angle of 90° between the circumferential surface of the shaft and the end face of the roller part in the step-down roller.

The end film was then wound up on the step-down roller with at least the second end of the end film in contact with the outer circumferential surface of the roller section and the first end of the end film (i.e., the gripping mark) separated from the roller section and facing the shaft with a gap in between. The width of the contact portion of the end film with the roller section was 200 mm (80% when the width of the end film is taken as 100%). The line speed of the end film was 350 mm/s. The number of windings (number of layers in the end film roll) was 7,000. The collected end film was then visually observed to check for the presence or absence of breakage. The results are shown in Table 1.

[Examples 2 and 3]
The end film was collected in the same manner as in Example 1, except that the step-down roller was changed to a tapered roller (see FIG. 5) having the taper angle shown in Table 1. The tapered roller was made of ABS. The maximum outer diameter of the tapered roller was 92.5 mm, and the minimum outer diameter was 85 mm or less.
More specifically, the end film was wound around the tapered roller in a state where at least the second end of the end film was in contact with the tapered surface and the first end of the end film (i.e., the gripping mark) was facing a portion of the tapered surface that was smaller in diameter than the contact portion of the second end. The width of the contact portion of the end film with the tapered surface was 100 mm (40% when the width of the end film is 100%). The line speed of the end film was 350 mm/s. The number of windings (number of layers in the end film roll) was 7000. The collected end film was then visually observed to confirm the presence or absence of breakage. The results are shown in Table 1.

[Example 4]
The end film was collected in the same manner as in Example 1, except that the stretched film made of the PC resin obtained in Preparation Example 1 was replaced with the stretched film made of the PET obtained in Preparation Example 2. The collected end film was visually observed to check for breakage. The results are shown in Table 1.

[Example 5]
The end film was collected in the same manner as in Example 1, except that the stretched film made of the PC resin obtained in Preparation Example 1 was replaced with the stretched film made of the acrylic resin obtained in Preparation Example 3. The collected end film was visually observed to check for breakage. The results are shown in Table 1.

[Example 6]
The end film was collected in the same manner as in Example 1, except that the stretched film made of the PC resin obtained in Preparation Example 1 was replaced with the stretched film made of the COP resin obtained in Preparation Example 4. The collected end film was visually observed to check for breakage. The results are shown in Table 1.

[Comparative Example 1]
In the same manner as in Example 1, the stretched film made of the PC resin obtained in Preparation Example 1 was cut to obtain two end films and a product film.
Next, a cylindrical winding roller was prepared. The winding roller was made of ABS. The outer diameter of the winding roller was 92.5 mm.
Next, an attempt was made to wind up the end film while the entire end film, including the grip marks of the clip, was in contact with the outer circumferential surface of the winding roller. However, the end film broke. The results are shown in Table 1. The line speed of the end film was 350 mm/s.

[Comparative Example 2]
An attempt was made to recover the end film in the same manner as in Example 1, except that the step-down roller was changed to a taper roller (see FIG. 5) having the taper angle shown in Table 1. However, the end film broke. The results are shown in Table 1.
In the comparative example, the taper angle was insufficient, and the entire end film, including the grip marks of the clip, was in contact with the tapered surface when the end film was wound up.

[evaluation]
As is clear from Table 1, when the end film is wound up in a state where the gripping marks of the clip contained in the end film are not in contact with the winding member, breakage of the end film can be prevented, and the end film can be stably wound up into a roll.

The manufacturing method of the end film roll of the present invention can produce end film rolls that can be reused as raw materials for various industrial products. The end films recovered as end film rolls are particularly suitable for use as recycled resin raw materials for optical films.

REFERENCE SIGNS LIST 1 Resin film 2 Stretched film 3 Clip grip mark 4 End film 5 Winding member 100 End film roll

Claims (3)

a step of stretching a long resin film in a direction intersecting with a longitudinal direction while holding both ends of the long resin film in a width direction with clips to prepare a stretched film;
a step of cutting each of the two end portions including the gripping marks of the clip from the stretched film to obtain an end film including the gripping marks;
a winding member winding up the end film,
The end film has a first end portion where the gripping mark is located and a second end portion opposite the first end portion in the width direction,
A method for manufacturing an end film roll, wherein, in a step in which the winding member winds up the end film, the second end is in contact with the winding member and the first end is located away from the winding member. The winding member includes a shaft and a roller portion provided on the shaft, the roller portion having a diameter larger than that of the shaft;
The manufacturing method for an end film roll according to claim 1 , wherein, in the step of winding up the end film by the winding member, the second end contacts the roller portion and the first end faces the shaft with a gap therebetween. The winding member has a tapered surface that becomes smaller in diameter from one end to the other end in the axial direction,
2. The method for manufacturing an end film roll according to claim 1, wherein, in the process in which the winding member winds up the end film, the second end contacts the tapered surface, and the first end faces, with a gap therebetween, a portion of the tapered surface that is smaller in diameter than the contact portion of the second end.

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