Film roll and production method for same

Abstract

This film roll includes a winding core and a long film wound around the winding core. The long film includes: two knurl regions including a plurality of protrusions provided at both ends in the film width direction; and a flat region provided between the two knurl regions. The film roll includes: two large diameter parts on which the knurl regions of the long film are wound; and a small diameter part which is provided between the two large diameter parts and on which the flat region of the long film is wound. The difference in diameter between a large diameter part and a small diameter part of a roll film satisfies specific requirements. The air layer thickness between the wound long films at the center of the film roll in the roll axis direction is within a specific range.

Description

Film roll and manufacturing method thereof

[0001] The present invention relates to a film roll and a method for producing the same.

[0002] The film is usually produced as a long film, then wound around an appropriate core to form a film roll, and stored and transported in this film roll state (Patent Documents 1 and 2).

[0003] Japanese Patent No. 6451338 Japanese Patent Application Laid-Open No. 2023-15895

[0004] A conventional method for winding long films is the gap winding method, in which the long film is wound around a gap roll located away from the film roll being manufactured, and then the wound long film is wound around a core. However, with this gap winding method, a large amount of air space is trapped between the wound long film, making the film roll prone to "buckling."

[0005] "Buckling" refers to a depression formed when a film roll is partially recessed in the radial direction. This buckling is likely to occur in areas where the air layer between overlapping long films is thick. In areas where this buckling occurs, the long film deforms, and a film surface defect known as a "lump defect" can occur. "Lump defects" generally occur as defects with a diameter of approximately 10 mm or less. Lumber defects are usually formed when a thick air layer inside the film roll increases the amount of vertical drop of the long film inside the film roll due to gravity, causing the long film to bend.

[0006] The touch winding method is known as a winding method that suppresses such gravity-induced drops and reduces the occurrence of lumpy defects. In the touch winding method, a long film is wound around a pressure roll that is set up to press the film roll in the process of being manufactured across the entire axial direction of the roll, and then the wound long film is wound while being pressed against the film roll in the process of being manufactured by the pressure roll. In the touch winding method, the long film is wound while being pressed against the film roll in the process of being manufactured across the entire width direction by the pressure roll, thereby reducing the air gap between the long films being wound. This is expected to suppress the occurrence of buckling and reduce the occurrence of lumpy defects.

[0007] However, with the touch winding method, the air gap between the overlapping long films is too small, which can cause the long films to stick together and lead to "gauge bands." A "gauge band" refers to a band-like raised portion (large diameter portion) extending circumferentially around the film roll. Gauge bands are usually formed by bending the long film, which can cause defects in the long film.

[0008] Therefore, the applicant developed a knurl touch winding method as a winding method that can suppress the above-mentioned bump defects and gauge bands. In the knurl touch winding method, two knurl regions with multiple convex portions are formed on both ends of a long film in the film width direction. The long film with the knurl regions formed is then wound around a touch roll, and the wound long film is then wound around a winding core. The winding is performed while the touch roll is in contact with the film roll in the middle of production. The knurl regions, which include the convex portions, are thicker than the flat regions between the knurl regions. Therefore, in general, the knurl regions of the wound film roll come into contact with the touch roll, while the flat regions do not.

[0009] Because the knurled region of the long film is thicker than the flat region, the resulting film roll has a large diameter portion where the knurled region is wound and a small diameter portion where the flat region is wound. The large diameter portion has a relatively large diameter because it is formed by winding a knurled region having a convex portion. The large diameter portion is wound while in contact with the touch roll, so the overlapping long films can be in close contact with each other. Therefore, in the large diameter portion, the air layer between the long films is relatively small or there is no air layer. On the other hand, the small diameter portion has a relatively small diameter because it is formed by winding a flat region without a convex portion. The small diameter portion is wound without contacting the touch roll, so there is a relatively large air layer between the overlapping long films, and the overlapping long films usually do not contact each other.

[0010] Film rolls manufactured using this knurl-touch winding method have a difference in diameter between the large-diameter and small-diameter sections. Therefore, a space is formed near the boundary between the large-diameter and small-diameter sections, allowing the long film to move. If the long film in the small-diameter section falls due to gravity during storage, causing the long film to move partially or entirely inward in the roll axial direction, buckling can occur near the boundary between the large-diameter and small-diameter sections. Specifically, this buckling is likely to occur just inside the large-diameter section in the roll axial direction. When this buckling occurs, defects can occur in the long film unwound from the film roll. These defects usually occur just inside the knurl region in the film width direction, and are therefore located near the end of the long film in the film width direction when viewed as a whole. Therefore, they are sometimes referred to as "end defects" below.

[0011] The present invention has been made in view of the above problems, and an object of the present invention is to provide a film roll capable of suppressing gauge bands, bump defects, and edge defects, and a method for manufacturing the same.

[0012] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that a knurl touch winding method, which involves devising an arrangement of protrusions formed in the knurl region, can appropriately control the shape profile of a film roll and realize a film roll that can solve the above-mentioned problems, and have completed the present invention. That is, the present invention includes the following.

[0013] <1> A film roll having a winding core and a long film wound around the winding core; the long film includes two knurled regions, each including a plurality of convex portions, provided at both ends in a film width direction, and a flat region provided between the two knurled regions; the film roll includes two large diameter portions around which the knurled regions of the long film are wound, and a small diameter portion, provided between the two large diameter portions, around which the flat region of the long film is wound; a first winding diameter difference ΔD1 expressed by the following formula (1) and a second winding diameter difference ΔD2 expressed by the following formula (2) are both smaller than 0.3 mm, and at least one of the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 is 0.05 mm or more; and an air layer thickness between the long films wound at the center of the film roll in the roll axis direction is 0.9 μm or more and 2.0 μm or less. (In formula (1), D Ｎ１（ＭＡＸ） represents the maximum diameter of one of the two large diameter portions of the film roll, and D Ｆ１（ＡＶＥ） represents the average diameter of the small diameter portion on the side of the one large diameter portion of the film roll, and in formula (2), D Ｎ２（ＭＡＸ） represents the maximum diameter of the other of the two large diameter portions of the film roll, and D Ｆ２（ＡＶＥ）represents the average value of the diameters of the small diameter portions on the other large diameter portion side of the film roll.) <2> The film roll according to <1>, wherein the knurl region of the long film alternates between knurl portions having the convex portions and gap portions not having the convex portions in the longitudinal direction of the film; and the pitch of the knurl portions in the longitudinal direction of the film is 20 mm or more and 100 mm or less. <3> The film roll according to <1> or <2>, wherein the height of the convex portions is 1 μm or more and 10 μm or less. <4> The film roll according to any one of <1> to <3>, wherein the long film contains a cycloolefin polymer. <5> The film roll according to any one of <1> to <4>, wherein the length of the long film is 2,000 m or more and 10,000 m or less. <6> A method for manufacturing a film roll having a winding core and a long film wound around the winding core, wherein the long film includes two knurl regions each including a plurality of convex portions provided at both ends in the film width direction, and a flat region provided between the two knurl regions, wherein the knurl regions of the long film include knurl portions having the convex portions and spaced portions having no convex portions alternately in the film longitudinal direction, and the pitch of the knurl portions in the film longitudinal direction is 20 mm or more and 100 mm or less, and the manufacturing method includes the steps of: winding the long film around a touch roll, and winding the long film wound around the touch roll onto the winding core while bringing the touch roll into contact with the knurl regions of the long film. <7> The method for manufacturing a film roll according to <6>, further including the step of forming the knurl regions in an unprocessed film to obtain the long film. <8> The method for producing a film roll according to <7>, which includes forming the knurled portions by irradiating a laser beam. <9> The method for producing a film roll according to <7> or <8>, wherein the step of forming the knurled portions in the unprocessed film includes oscillating the formation positions of the knurled portions in the film width direction; and the ratio of the oscillation amount of the knurled portions to the width of one knurled portion is 0.5 or more and 1.0 or less.<10> The method for producing a film roll according to any one of <6> to <9>, wherein the height of the convex portions is 1 μm or more and 10 μm or less. <11> The method for producing a film roll according to any one of <6> to <10>, wherein the long film contains a cycloolefin polymer. <12> The method for producing a film roll according to any one of <6> to <11>, wherein the length of the long film to be wound is 2,000 m or more and 10,000 m or less. <13> The method for producing a film roll according to any one of <6> to <12>, wherein the axial length of the touch roll is equal to or greater than the width of the long film, and in the step of winding the long film around the winding core, the touch roll presses the film roll in the middle of production toward the center of the winding core with a load of 50 N / m to 200 N / m. <14> The method for producing a film roll according to any one of <6> to <13>, wherein the film winding speed of the long film is 10 m / min or more and 150 m / min or less.

[0014] According to the present invention, it is possible to provide a film roll capable of suppressing gauge bands, bump defects, and edge defects, and a method for manufacturing the same.

[0015] FIG. 1 is a front view schematically showing a film roll according to one embodiment of the present invention. FIG. 2 is a plan view schematically showing an enlarged view of the vicinity of one end (first end) of a long film according to one embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing a cross section of a linear concave-convex portion of a long film according to one embodiment of the present invention, cut along a plane perpendicular to the extension direction of the concave-convex portion. FIG. 4 is a plan view schematically showing the planar shape of one of the concave-convex portions of a long film according to one embodiment of the present invention, as viewed from the film thickness direction. FIG. 5 is a plan view schematically showing an enlarged view of the vicinity of the other end (second end) of a long film according to one embodiment of the present invention. FIG. 6 is a schematic perspective view for explaining a method for measuring the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 of a film roll. FIG. 7 is a diagram showing the air layer thickness d between long films included in a film roll. ａｉｒFIG. 8 is a schematic cross-sectional view of a film roll for explaining a method for measuring the shape profile of the outermost peripheral surface near the end in the roll axis direction of a film roll according to one example. FIG. 9 is a side view schematically showing a film roll manufacturing apparatus according to one embodiment of the present invention. FIG. 10 is a plan view schematically showing a state of a long film being wound around a core in a film roll manufacturing method according to one embodiment of the present invention. FIG. 11 is a front view schematically showing a film roll according to a modified example of one embodiment of the present invention. FIG. 12 is a plan view schematically showing an enlarged view of the vicinity of one end (first end) of a long film according to a modified example of one embodiment of the present invention.

[0016] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be modified and implemented as desired within the scope of the claims and their equivalents.

[0017] <Overview of Film Roll> Fig. 1 is a front view schematically showing a film roll 1 according to one embodiment of the present invention. Fig. 1 shows a state in which a portion of a long film 100 is pulled out from the film roll 1, but the portion of the long film 100 does not have to be pulled out. As shown in Fig. 1, the film roll 1 according to this embodiment has a winding core 10 and the long film 100 wound around this winding core 10. In general, the film longitudinal direction, film width direction, and film thickness direction of the long film 100 correspond to the roll circumferential direction, roll axial direction, and roll radial direction of the film roll 1.

[0018] <Description of Winding Core 10> Typically, the winding core 10 is a member having a circumferential surface 10S with a cylindrical side surface shape, and for example, a cylindrical or columnar member can be used. The circumferential surface 10S of the winding core 10 generally forms a smoothly curved surface, and the long film 100 is wound and overlapped onto this circumferential surface 10S to form a film roll 1. The diameter of the winding core 10 may be appropriately selected depending on factors such as the material, application, and length of the long film 100. In one example, the specific diameter of the winding core 10 is preferably 100 mm or more, more preferably 150 mm or more, and preferably 400 mm or less, more preferably 350 mm or less.

[0019] <Description of the Shape of the Long Film 100> The long film 100 is a long film. A "long" film refers to a film having a length that is five times or more its width, preferably ten times or more its width, and specifically refers to a film having a length that can be wound into a roll for storage or transportation. There is no particular upper limit to the length of the long film 100, and it can be, for example, 100,000 times or less its width.

[0020] The long film 100 includes two knurl regions 110L and 110R, each including a plurality of convex portions, provided at both ends in the film width direction, and a flat region 120 provided between these two knurl regions 110L and 110R. Hereinafter, one end of the long film 100 in the film width direction may be referred to as the "first end," and the other end may be referred to as the "second end." In this embodiment, an example will be described in which a plurality of uneven portions 130, including concave and convex portions, are formed in the long film 100, and the knurl regions 110L and 110R, each including a plurality of convex portions in the uneven portion 130, are provided at both ends of the long film 100 in the film width direction.

[0021] 2 is an enlarged plan view schematically illustrating the vicinity of one end (first end) of the long film 100 according to one embodiment of the present invention. As shown in FIG. 2, the knurl region 110L at the first end of the long film 100 includes knurl portions 111L and spacing portions 112L alternately arranged in the longitudinal direction of the film.

[0022] The knurl portion 111L represents a portion in the knurl region 110L having a convex portion. In the example shown in this embodiment, the uneven portion 130 including the concave and convex portions is formed in the long film 100 as described above, and thus a plurality of the knurl portions 111L including the convex portions in the uneven portion 130 are formed side by side in the knurl region 110L.

[0023] In this embodiment, an example is shown in which the uneven portion 130 is formed in a continuous line shape when viewed from the thickness direction of the film. Such a continuous linear uneven portion 130 can be formed, for example, by irradiating with laser light. Therefore, the uneven portion 130 may be formed as a continuous line drawn in a single stroke, as a trace of the movement of the irradiation point of the laser light. Here, "drawn in a single stroke" refers to the shape of a continuous line without any interruptions along the way.

[0024] FIG. 3 is a cross-sectional view schematically illustrating a linear uneven portion 130 of a long film 100 according to one embodiment of the present invention, cut along a plane perpendicular to the extension direction of the uneven portion 130. As shown in FIG. 3, the uneven portion 130 may include a recess 131 and a protrusion 132. For example, the uneven portion 130 formed by irradiation with laser light typically has a recess 131 and protrusions 132 on both sides of the recess 131. The recess 131 may correspond to a portion where resin has been removed by thermal melting or ablation due to irradiation with laser light. Furthermore, the protrusion 132 may correspond to a raised portion of resin that has been heated and fluidized by irradiation with the laser light. Because the protrusion 132 protrudes from the surrounding surface 100U of the long film 100, the effective thickness of the long film 100 is increased in the knurl portion 111L having the uneven portion 130.

[0025] The height H of the protrusions 132 may be uniform or non-uniform. In one example, the height range of the protrusions 132 is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more, and is preferably 10 μm or less, more preferably 9 μm or less, and even more preferably 8 μm or less.

[0026] The line width W of the concave-convex portion 130 may be uniform or non-uniform. In one example, the line width W of the concave-convex portion 130 is preferably 0.1 μm or more, more preferably 0.15 μm or more, and even more preferably 0.2 μm or more, and is preferably 1 μm or less, more preferably 0.75 μm or less, and even more preferably 0.5 μm or less.

[0027] The continuous linear concave-convex portion 130 may be formed to have a specific planar shape as needed. The term "planar shape" refers to the shape as viewed from the film thickness direction, unless otherwise specified. When the concave-convex portion 130 has a specific planar shape, the concave portions 131 and convex portions 132 included in the concave-convex portion 130 may also have the specific planar shape. For example, the continuous linear concave-convex portion 130 may have a shape with multiple corners.

[0028] 4 is a plan view schematically illustrating the planar shape of one of the concave-convex portions 130 of the long film 10 according to one embodiment of the present invention, as viewed from the film thickness direction. When the concave-convex portion 130 is viewed from the film thickness direction, a corner 133 of the concave-convex portion 130 can be a connecting portion connecting two straight line portions 134 and 135 included in the concave-convex portion 130. In FIG. 4, this corner 133 can correspond to the apex of the angle formed between the straight line portion 134 sloping upward to the right and the straight line portion 135 sloping downward to the right. Therefore, the corner 133 is inclined at an angle θ depending on the extending direction of the straight line portion 134 and the extending direction of the straight line portion 135. １３３ The angle θ of the corner 133 １３３ is preferably 80° or more, more preferably 85° or more, even more preferably 88° or more, and is preferably 100° or less, more preferably 95° or less, even more preferably 92° or less. For example, the angle θ １３３ The angle θ of the plurality of corners 133 may be 90°. １３３ may be the same or different.

[0029] The number of corners 133 included in one uneven portion 130 is not particularly limited. In this embodiment, an example is shown in which the continuous linear uneven portion 130 has an endless polygonal shape and the number of corners 133 included in one uneven portion 130 is 24. However, the number of corners 133 included in one uneven portion 130 may be 24 or more (e.g., 32, 40, 48, or 56) or may be less than 24 (e.g., 16, 8, or 4). Furthermore, the planar shape of the uneven portion 130 may be a shape other than an endless shape, and may be a shape with ends, such as a broken line shape.

[0030] As shown in FIG. 2, the length L of each knurl portion 111L in the longitudinal direction of the film １１１Ｌ The range of the length L is usually 20 mm or less, preferably 19 mm or less, more preferably 15 mm or less, and even more preferably 10 mm or less. １１１Ｌ When the length L of the knurl portion 111L is equal to or less than the upper limit, the knurl portion 111L (and the uneven portion 130 in the knurl portion 111L) can be formed in a short time, and therefore the production speed of the film roll 1 can be improved. １１１Ｌ The lower limit of the range may be set within a range in which a film roll 1 having a desired shape profile can be obtained, and is preferably 0.1 mm or more, more preferably 0.5 mm or more, and even more preferably 1 mm or more. When one uneven portion 130 is formed in one knurl portion 111L as in the example shown in this embodiment, the length of the uneven portion 130 in the longitudinal direction of the film is equal to the length L of the knurl portion 111L. １１１Ｌ The length L of the plurality of knurled portions 111L corresponds to １１１Ｌ may be the same or different.

[0031] Also, the width W of each knurl portion 111L in the film width direction １１１Ｌ The range is preferably 3 mm or more, more preferably 5 mm or more, even more preferably 7 mm or more, and is preferably 20 mm or less, more preferably 17 mm or less, even more preferably 15 mm or less. When one uneven portion 130 is formed in one knurl portion 111L as in the example shown in this embodiment, the width of the uneven portion 130 in the film width direction is the width W of the knurl portion 111L.１１１Ｌ The width W of the plurality of knurled portions 111L corresponds to １１１Ｌ may be the same or different.

[0032] The positions of the multiple uneven portions 130 formed in the knurl region 110L in the film width direction may be different, but are usually the same. When the positions of the multiple uneven portions 130 formed in the knurl region 110L in the film width direction are the same, the positions of the multiple knurl portions 111L including the uneven portions 130 in the film width direction may also be the same. In this case, the width W of each knurl portion 111L in the film width direction １１１Ｌ can be equal to the width (dimension in the film width direction) of the knurl region 110L including the knurl portion 111L.

[0033] Pitch P of the knurled portion 111L in the longitudinal direction of the film １１０Ｌ The range of the pitch P is preferably 20 mm or more, more preferably 25 mm or more, and even more preferably 30 mm or more, and is preferably 100 mm or less, more preferably 85 mm or less, and even more preferably 70 mm or less. １１０Ｌ is usually the length L of one of the knurled portions 111L. １１１Ｌ and the length L in the longitudinal direction of the film of the gap 112L immediately downstream of the knurl portion 111L. １１２Ｌ In addition, when one uneven portion 130 is formed for one knurl portion 111L by laser light, the pitch P of the knurl portion 111L is １１１Ｌ The pitch P of the plurality of knurled portions 111L may correspond to the distance in the longitudinal direction of the film from the start point of forming the concave-convex portion 130 by the laser light (the point where the laser light starts to hit) to the start point of forming the next concave-convex portion 130. １１１Ｌ may be the same or different.

[0034] The spacing portion 112L represents a portion within the knurl region 110L that does not have a convex portion. A plurality of these spacing portions 112L are formed side by side as portions between the plurality of knurl portions 111L. In the example shown in this embodiment, the uneven portion 130 is not formed in the spacing portion 112L, and therefore the spacing portion 112L does not have a convex portion 132. Furthermore, since the spacing portion 112L does not have the convex portion 132, the substantial thickness of the long film 100 is thinner in the spacing portion 112L than in the knurl portion 111L.

[0035] Length L of each gap 112L in the longitudinal direction of the film １１２Ｌ The range is preferably 15 mm or more, more preferably 20 mm or more, even more preferably 25 mm or more, and is preferably 95 mm or less, more preferably 80 mm or less, even more preferably 65 mm or less. When one uneven portion 130 is formed in one knurl portion 111L as in the example shown in this embodiment, the distance in the longitudinal direction of the film between adjacent uneven portions 130 is the length L of the spacing portion 112L. １１２Ｌ The length L of the plurality of gaps 112L corresponds to １１２Ｌ may be the same or different.

[0036] Length L of the knurl portion 111L in the longitudinal direction of the film １１１Ｌ and the length L of the spacing portion 112L １１２Ｌ The ratio (L １１２Ｌ / L １１１Ｌ The range of the length L of the plurality of knurled portions 111L is preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more, and is preferably 100 or less, more preferably 60 or less, and even more preferably 40 or less. １１１Ｌ are different, and the length L of the plurality of spacing portions 112L is １１２Ｌ are different, their lengths L １１１Ｌ and length L １１２Ｌ It is preferable that the ratio of the average of the above to the above range.

[0037] As described above, the knurl region 110L including the knurl portion 111L and the spacing portion 112L is provided at the first end of the long film 100. The distance from the edge 140L on the first end side of the long film 100 to the knurl region 110L may be 0 mm or greater. Therefore, the long film 100 may have an arbitrary region outside the knurl region 110L in the film width direction. However, since the flat region 120 of the long film 100 is generally used for the final application, it is preferable that the arbitrary region is small, and more preferably, absent, from the perspective of widening the range of use for such final applications. Usually, the knurl region 110L has a width W of the knurl portion 111L included in the knurl region 110L. １１１Ｌ It has a width in the same range as the range of

[0038] 5 is an enlarged plan view schematically illustrating the vicinity of the other end (second end) of the long film 100 according to one embodiment of the present invention. As shown in FIG. 5, the knurl region 110R at the second end of the long film 100 includes knurl portions 111R and spacing portions 112R alternately arranged in the longitudinal direction of the film. This knurl region 110R and the knurl portions 111R and spacing portions 112R included in the knurl region 110R may be formed in the same manner as the knurl region 110L and the knurl portions 111L and spacing portions 112L included in the knurl region 110L described above, except that they are provided at the second end of the long film 100 in the film width direction.

[0039] Therefore, the knurl portion 111R represents a portion in the knurl region 110R having a convex portion. In the example shown in this embodiment, the uneven portion 130 is formed in the long film 100, and thus a plurality of knurl portions 111R including convex portions 132 (see FIG. 3) in the uneven portion 130 are formed side by side in the knurl region 110R. The uneven portion 130, the concave portion 131 (see FIG. 3), and the convex portion 132 in the knurl portion 111R may be the same as the uneven portion 130, the concave portion 131, and the convex portion 132 in the knurl portion 111L. In addition, the length L of each knurl portion 111R in the longitudinal direction of the film １１１Ｒ The width W of each knurl portion 111R in the film width direction １１１Ｒthe pitch P of the knurled portion 111R in the longitudinal direction of the film １１０Ｒ The range is the length L of each knurl portion 111L in the longitudinal direction of the film. １１１Ｌ The width W of each knurl portion 111L in the film width direction １１１Ｌ and the pitch P of the knurled portion 111L in the longitudinal direction of the film. １１０Ｌ Furthermore, the positions of the multiple uneven portions 130 formed in the knurl region 110R in the film width direction may be different, but are usually the same. When the positions of the multiple uneven portions 130 formed in the knurl region 110R in the film width direction are the same, the positions of the multiple knurl portions 111R including the uneven portions 130 in the film width direction may also be the same. In this case, the width W per knurl portion 111R in the film width direction １１１Ｒ can be equal to the width (dimension in the film width direction) of the knurl region 110R including the knurl portion 111R.

[0040] Furthermore, the gap 112R represents a portion of the knurl region 110R that does not have a convex portion. In the example shown in this embodiment, the gap 112R does not have the uneven portion 130 formed therein, and therefore does not have a convex portion 132. The length L of each gap 112R in the longitudinal direction of the film is １１２Ｒ and the length L of the knurl portion 111R in the longitudinal direction of the film. １１１Ｒ and the length L of the gap 112R １１２Ｒ The ratio (L １１２Ｒ / L １１１Ｒ ) is the length L per one gap 112L in the longitudinal direction of the film. １１２Ｌ and the length L of the knurl portion 111L in the longitudinal direction of the film. １１１Ｌ and the length L of the spacing portion 112L １１２Ｌ The ratio (L １１２Ｌ / L １１１Ｌ The length L of the plurality of knurled portions 111R may be the same as the range of the length L of the plurality of knurled portions 111R. １１１Ｒ are different, and the length L of the plurality of spacing portions 112R １１２Ｒ are different, their lengths L １１１Ｒ and length L １１２ＲIt is preferable that the ratio of the average of the above to the above range.

[0041] Furthermore, the long film 100 may have an optional region outside the knurl region 110R in the film width direction. In this case, the distance from the edge 140R on the second end side of the long film 100 to the knurl region 110R may be 0 mm or greater. In particular, it is preferable that the optional region is small, and more preferably, it is absent. Usually, the knurl region 110R has a width W of the knurl portion 111R included in the knurl region 110R. １１１Ｒ It has a width in the same range as the range of

[0042] As shown in Figure 1, the elongated film 100 has a flat region 120 between the two knurl regions 110L and 110R in the film width direction. This flat region 120 usually does not have a protrusion 132 (see Figure 3), and therefore has a smaller effective thickness than the knurl portions 111L and 111R of the knurl regions 110L and 110R. Generally, this flat region 120 is used for the final use of the elongated film 100.

[0043] The length, width, and thickness of the long film 100 may be set within a range depending on the intended use of the long film 100 .

[0044] In one example, the length of the long film 100 is preferably 2000 m or more, more preferably 2500 m or more, even more preferably 3000 m or more, and preferably 10000 m or less, more preferably 8000 m or less, even more preferably 6000 m or less.

[0045] In one example, the width of the long film 100 is preferably 700 mm or more, more preferably 1000 mm or more, even more preferably 1200 mm or more, and preferably 2500 mm or less, more preferably 2200 mm or less, even more preferably 2000 mm or less.

[0046] In one example, the thickness of the long film 100 is preferably 11 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more, and is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 150 μm or less. Unless otherwise specified, the "thickness of the long film 100" refers to the thickness of the long film 100 in a portion without the uneven portion 130, and typically refers to the thickness in the flat region 120. Generally, thin films have poor rigidity and tend to be prone to defects. However, the film roll 1 according to this embodiment can suppress gauge bands, bump defects, and edge defects. Therefore, even when such a thin long film 100 is used, the occurrence of defects due to storage and transportation in the film roll 1 state can be suppressed, thereby achieving excellent quality stability.

[0047] <Explanation of the External Shape of the Film Roll 1> As described above, the film roll 1 is a roll formed by winding up the long film 100, which includes two knurl regions 110L and 110R and a flat region 120 provided between the two knurl regions 110L and 110R. Therefore, as shown in Fig. 1 , the film roll 1 includes two large diameter portions 210L and 210R around which the knurl regions 110L and 110R are wound, and a small diameter portion 220 around which the flat region 120 is wound.

[0048] Since the two knurl regions 110L and 110R are provided at both ends of the long film 100 in the film width direction, the large diameter portions 210L and 210R are usually provided at both ends of the film roll 1 in the roll axis direction. Hereinafter, the large diameter portion 210L formed by winding the knurl region 110L at the first end of the long film 100 may be referred to as the "first large diameter portion" 210L, and the large diameter portion 210R formed by winding the knurl region 110R at the second end of the long film 100 may be referred to as the "second large diameter portion" 210R. The first large diameter portion 210L and the second large diameter portion 210R are portions formed by winding the knurl regions 110L and 110R, including the knurl regions 111L and 111R, which have a relatively large effective thickness, and therefore have a diameter relatively larger than that of the small diameter portion 220.

[0049] Since the flat region 120 is provided between the two knurl regions 110L and 110R, the small diameter portion 220 is usually provided between the two large diameter portions 210L and 210R in the roll axis direction of the film roll 1. The small diameter portion 220 is usually a portion where the flat region 120, which has a substantial thickness smaller than the knurl portions 111L and 111R of the knurl regions 110L and 110R, is wound, and therefore has a diameter relatively smaller than the first large diameter portion 210L and the second large diameter portion 210R.

[0050] This film roll 1 satisfies the following requirements (R1), (R2), and (R3) in combination: (R1) Both the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 of the film roll 1 are smaller than 0.3 mm. (R2) At least one of the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 of the film roll 1 is 0.05 mm or more. (R3) The air layer thickness d between the wound long films 100 at the center of the film roll 1 in the roll axis direction is ａｉｒ However, the thickness is 0.9 μm or more and 2.0 μm or less.

[0051] Requirement (R1) will be described below. Requirement (R1): Both the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 of the film roll 1 are usually less than 0.30 mm, preferably less than 0.20 mm, and more preferably less than 0.15 mm. Here, the first winding diameter difference ΔD1 of the film roll 1 represents a value expressed by the following formula (1). Furthermore, the second winding diameter difference ΔD2 of the film roll 1 represents a value expressed by the following formula (2).

[0052]

[0053] (In formula (1), D Ｎ１（ＭＡＸ） represents the maximum diameter of the first large diameter portion (one of the two large diameter portions) 210L of the film roll 1; D Ｆ１（ＡＶＥ） represents the average value of the diameter of the small diameter portion 220 on the side of the first large diameter portion (one of the large diameter portions) 210L of the film roll 1. Ｎ２（ＭＡＸ） represents the maximum diameter of the second large diameter portion (the other of the two large diameter portions) 210R of the film roll 1; D Ｆ２（ＡＶＥ）represents the average value of the diameter of the small diameter portion 220 on the side of the second large diameter portion (the other large diameter portion) 210R of the film roll 1.)

[0054] The first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 of the film roll 1 can be measured by the following measurement method. FIG. 6 is a schematic perspective view illustrating a method for measuring the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 of the film roll 1. As shown in FIG. 6 , a laser displacement meter 300L and a laser displacement meter 300R are installed facing the film roll 1 at a position away from the outermost peripheral surface 1S of the film roll 1. In this case, the laser displacement meter 300L and the laser displacement meter 300R are installed so that the optical axes 310L and 310R of the measurement laser beams emitted from the laser displacement meter 300L and the laser displacement meter 300R are perpendicular to the central axis 10A of the winding core 10. The distance from the laser displacement meter 300L and the laser displacement meter 300R to the surface of the winding core 10 can be, for example, 580 mm. While rotating the film roll 1 in the circumferential direction around the central axis 10A of the winding core 10, the laser displacement meters 300L and 300R measure the distance from the laser displacement meters 300L and 300R to the outermost surface 1S of the film roll 1. From this measurement, the distance from the laser displacement meters 300L and 300R to the outermost surface 1S of the film roll 1 can be obtained when the circumferential rotation angle φ of the film roll 1 is in the range of 0°≦φ<360°.

[0055] Therefore, by performing the above-mentioned measurements on the first large diameter portion 210L and the second large diameter portion 210R of the film roll 1, a shape profile of the outermost surface 1S of the first large diameter portion 210L and the second large diameter portion 210R can be obtained, and the diameters of the first large diameter portion 210L and the second large diameter portion 210R can be obtained from the shape profile. Therefore, the largest value among the measured values ​​of the diameter of the first large diameter portion 210L when the rotation angle φ is 0°≦φ<360° is defined as D Ｎ１（ＭＡＸ） The largest value among the measured diameters of the second large diameter portion 210R when the rotation angle φ is 0°≦φ<360° is adopted as D Ｎ２（ＭＡＸ） Adopted as.

[0056] Furthermore, by performing the above-mentioned measurement on the small diameter portion 220 of the film roll 1, a shape profile of the outermost peripheral surface 1S of the small diameter portion 220 can be obtained, and the diameter of the small diameter portion 220 can be obtained from the shape profile. Ｆ１（ＡＶＥ） To obtain the diameter φ, the shape profile of the outermost surface 1S is measured in the small diameter portion 220 on the first large diameter portion 210L side of the film roll 1. Specifically, the shape profile of the outermost surface 1S is measured in a measurement range 221L in the small diameter portion 220 that is 10 cm to 20 cm away in the roll axis direction from the inner end of the first large diameter portion 210L (the inner end in the roll axis direction). Then, the diameter of the small diameter portion 220 on the first large diameter portion 210L side is obtained from the shape profile, and the average of the measured diameters of the small diameter portion 220 on the first large diameter portion 210L side when the rotation angle φ is 0°≦φ<360° is defined as D. Ｆ１（ＡＶＥ） It is usually calculated as D Ｆ２（ＡＶＥ） To obtain the diameter φ, the shape profile of the outermost surface 1S is measured in the small diameter portion 220 on the second large diameter portion 210R side of the film roll 1. Specifically, the shape profile of the outermost surface 1S is measured in a measurement range 221R in the small diameter portion 220 that is 10 cm to 20 cm away in the roll axis direction from the inner end of the second large diameter portion 210R (the inner end in the roll axis direction). Then, the diameter of the small diameter portion 220 on the second large diameter portion 210R side is obtained from the shape profile, and the average of the measured diameters of the small diameter portion 220 on the second large diameter portion 210R side when the rotation angle φ is 0°≦φ<360° is defined as D. Ｆ２（ＡＶＥ） Calculate as follows.

[0057] Then, the obtained D Ｎ１（ＭＡＸ） and D Ｆ１（ＡＶＥ） is substituted into Equation (1) to calculate the first winding diameter difference ΔD1 of the film roll 1. This first winding diameter difference ΔD1 corresponds to the difference in diameter between the first large diameter portion 210L and the small diameter portion 220 located inside in the roll axis direction, and corresponds to the size of a step that may occur between the first large diameter portion 210L and the small diameter portion 220. In addition, the obtained D Ｎ２（ＭＡＸ） and D Ｆ２（ＡＶＥ）into equation (2) to calculate the second winding diameter difference ΔD2 of the film roll 1. This second winding diameter difference ΔD2 corresponds to the difference in diameter between the second large diameter portion 210R and the small diameter portion 220 located inside the second large diameter portion 210R in the roll axis direction, and corresponds to the size of a step that may occur between the second large diameter portion 210R and the small diameter portion 220. Requirement (R1) indicates that this step is smaller than a certain threshold value.

[0058] Next, requirement (R2) will be described. Requirement (R2): At least one of the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 of the film roll 1 is usually 0.05 mm or more, preferably 0.06 mm or more, and more preferably 0.07 mm or more. It is even more preferable that both the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 of the film roll 1 are equal to or greater than the aforementioned threshold value.

[0059] As described above, the first winding diameter difference ΔD1 corresponds to the difference in diameter between the first large diameter portion 210L and the small diameter portion 220 located inside the first large diameter portion 210L in the roll axial direction, and corresponds to the magnitude of a step that may occur between the first large diameter portion 210L and the small diameter portion 220. Furthermore, as described above, the second winding diameter difference ΔD2 corresponds to the difference in diameter between the second large diameter portion 210R and the small diameter portion 220 located inside the second large diameter portion 210R in the roll axial direction, and corresponds to the magnitude of a step that may occur between the second large diameter portion 210R and the small diameter portion 220. Therefore, requirement (R1) indicates that at least one of these steps, and preferably both, is equal to or greater than a certain threshold.

[0060] Next, the requirement (R3) will be described. Requirement (R3): The thickness d of the air layer between the wound long films 100 at the center of the roll axis direction of the film roll 1 ａｉｒ However, it is usually 0.9 μm or more, preferably 1.0 μm or more, and usually 2.0 μm or less, preferably 1.7 μm or less, more preferably 1.4 μm or less.

[0061] The air layer thickness d ａｉｒ represents the thickness of each air layer between the long films 100 wound together in the film roll 1. This air layer thickness d ａｉｒ can be measured by the following measurement method.

[0062] FIG. 7 shows the thickness d of the air layer between the long films 100 included in the film roll 1. ａｉｒ7 is a schematic cross-sectional view of a film roll 1 for explaining a method for measuring the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 of the film roll 1 described above. As shown in FIG. 7 , a laser displacement meter 300L is placed facing the film roll 1, similar to the method for measuring the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 of the film roll 1 described above. While the film roll 1 is rotated in the circumferential direction around the central axis 10A of the winding core 10, the laser displacement meter 300L measures the distance from the laser displacement meter 300L to the outermost surface IS of the film roll 1 at the center in the roll axis direction of the film roll 1. This measurement allows the distance from the laser displacement meter 300L to the outermost surface IS of the film roll 1 to be obtained when the rotation angle φ of the film roll 1 in the circumferential direction (see FIG. 6 ) is in the range of 0°≦φ<360°. Then, from the measurement results, a shape profile of the outermost surface IS at the center in the roll axis direction of the film roll 1 is obtained, and an average diameter Rb is obtained when the rotation angle φ is in the range of 0°≦φ<360°. In addition, the average radius Ra of the core 10 at the center of the roll axis direction of the film roll 1, and the thickness d of one film at the center of the film width direction of the long film 100 are separately calculated. ｆｉｌｍ , and the length L of the long film 100 are measured.

[0063] Generally, the average radius Rb of the film roll 1 is expressed by the following formula (M1): Furthermore, generally, the length L of the long film 100 contained in the film roll 1 is expressed by the following formula (M2): where n represents the total number of turns of the long film 100 contained in the film roll 1.

[0064]

[0065] In formula (M2), n>>1, so we can approximate n+1≒n. Therefore, if we approximate n+1 to n in formula (M2), the total number of turns n can be expressed by formula (M3). Also, by solving formula (M1), the air layer thickness d ａｉｒ Therefore, the average radius Rb of the film roll 1, the average radius Ra of the winding core 10, and the thickness d of one sheet of the long film 100 at the center in the film width direction can be expressed by the formula (M4). ｆｉｌｍ , and the length L of the long film 100, using equations (M3) and (M4), the air layer thickness d ａｉｒcan be calculated.

[0066]

[0067] The film roll 1 according to this embodiment, which satisfies the above-described requirements (R1), (R2), and (R3) in combination, can suppress gauge bands, lumpy defects, and edge defects. Therefore, it can achieve excellent stability in appearance and quality during transportation and storage, and is expected to improve yield. More details are as follows.

[0068] The film roll 1 according to this embodiment can suppress the occurrence of gauge bands, thereby suppressing the occurrence of defects in the long film 100 included in the film roll 1 due to bending of the long film 100. In one example, when the film roll 1 is stored for 14 days in an environment with a temperature of 20°C to 25°C and a humidity of 50% RH to 70% RH, the occurrence of gauge bands (local band-shaped defects extending in the circumferential direction) can be suppressed.

[0069] As described above, gauge bands are generally likely to occur when there is an excessively small air layer between the long films 100 in the overlapping film roll 1. In this embodiment, as represented by requirement (R3), sufficient air layers are formed between the long films 100 in the film roll 1 to prevent the occurrence of gauge bands, thereby preventing the formation of gauge bands.

[0070] The film roll 1 according to this embodiment can suppress the occurrence of buckling. Therefore, the occurrence of small defects caused by the buckling can be suppressed. In one example, when the film roll 1 is stored for 14 days in an environment with a temperature of 20°C to 25°C and a humidity of 50% RH to 70% RH, the occurrence of small defects in the long film 100 contained in the film roll 1 can be suppressed. The small defects are typically observed as defects with a depth of 3 μm to 5 μm and a width of 3 mm to 5 mm. The small defects can be detected by unwinding the long film 100 from the film roll 1 at a line speed of 50 m / min and using a defect detector. This defect detector can be a detector that irradiates the long film 100 with light and detects defects based on the state of light reflected from the long film 100. When the long film is buckled, the light reflection state changes from areas without buckling, making it possible to detect the small defects using the defect detector. However, in order to evaluate nugget defects separately from edge defects, defects located within a distance of 0 mm to 40 mm inside the knurl region in the film width direction are not included in nugget defects.

[0071] As described above, pimple defects are generally likely to occur due to buckling that occurs when the air layer between the long films 100 becomes excessively large within the wound film roll 1. In this embodiment, as represented by requirement (R3), the air layer between the long films 100 can be made thin enough to prevent buckling, thereby preventing buckling and therefore preventing pimple defects.

[0072] The film roll 1 according to this embodiment can suppress edge defects. In one example, when the film roll 1 is stored for 14 days in an environment with a temperature of 20°C to 25°C and a humidity of 50% to 70% RH, the occurrence of edge defects in the long film 100 contained in the film roll 1 can be suppressed. The edge defects are typically observed as defects with a depth of 3 μm to 5 μm and a width of 3 mm to 5 mm. The edge defects can be detected by unwinding the long film 100 from the film roll 1 at a line speed of 50 m / min using the defect detector described above. However, to distinguish edge defects from small defects, only defects located within a distance of 0 mm to 40 mm inside the knurl region in the film width direction are detected as edge defects.

[0073] FIG. 8 is a schematic diagram illustrating a shape profile of the outermost peripheral surface of an example film roll 1 near the end in the roll axis direction. As shown in FIG. 8 , the roll film 1 has a relatively large diameter in the large diameter portions (i.e., the first large diameter portion 210L and the second large diameter portion 210R) and a relatively small diameter in the small diameter portion 220 located inside the large diameter portion 210L or 210R in the roll axis direction. At the boundary portion 230 between the large diameter portion 210L or 210R and the small diameter portion 220, the diameter may become particularly small locally due to gravity-induced movement of the long film 100. If the difference in diameter between the large diameter portion 210L or 210R and the small diameter portion 220 is large, a large step may form at the boundary portion 230. When a large step forms, deep buckling occurs at the point where stress is concentrated, causing the long film 100 to bend significantly, potentially resulting in end defects. In contrast, in this embodiment, as indicated by requirement (R1), the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 corresponding to the step can be made smaller than appropriate threshold values ​​confirmed experimentally, thereby suppressing buckling at the boundary portion 230 and suppressing the occurrence of end defects.

[0074] If the only purpose is to suppress end buckling, it is possible to eliminate the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2. However, if the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 were eliminated, the air layer between the long films 100 in the small diameter portion 220 would become too small, which could make it difficult to suppress gauge bands. Therefore, in this embodiment, as in requirement (R2), the lower limits of the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 are set to be equal to or greater than an appropriate threshold value, thereby achieving the suppression of all of gauge bands, pimple defects, and end defects.

[0075] In the past, it was difficult to realize a film roll 1 that satisfied requirements (R1) and (R2). In conventional film rolls, it was desirable to densely form convex portions in the knurl region to suppress winding slippage of the long film (a phenomenon in which the wound long film is displaced in the roll axial direction). Therefore, if the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 were to be reduced, it was considered to form the convex portions low. However, since the long film is wound a huge number of times during winding, many convex portions accumulate in the film roll. As a result, it was previously impossible to reduce the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2. Therefore, even if the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 could be reduced to zero without providing the knurl portion, it was difficult with conventional technology to keep the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 within an appropriate range that satisfied requirements (R1) and (R2).

[0076] In contrast to this, in this embodiment, the knurl portions 111L and 111R including the convex portions are not densely arranged in the knurl regions 110L and 110R, but are spaced apart by gaps 112L and 112R, and are arranged at a large pitch P １１１Ｌ and P １１１Ｒ It is formed with a large pitch P １１１ＬBy providing the knurled portions 111L, the knurled portions 111L of the long film 100 being wound are prevented from piling up in the first large diameter portion 210L where the knurled regions 110L are wound. Therefore, in the first large diameter portion 210L, the knurled portions 111L can be overlapped with each other with their positions shifted in the circumferential direction of the roll, so that the diameter of the first large diameter portion 210L does not become excessively large and can be kept within an appropriate range. Similarly, the large pitch P １１１Ｒ By providing the knurl portion 111R, even in the second large diameter portion 210R where the knurl region 110R is wound, it is possible to reduce the stacking of the knurl portions 111R of the long film 100 being wound, so that the diameter of the second large diameter portion 210R does not become excessively large and can be kept within an appropriate range. Therefore, in this embodiment, the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 can be kept within an appropriate range that satisfies the requirements (R1) and (R2).

[0077] The method for satisfying the requirements (R1) and (R2) is as described above. Therefore, it is preferable to set the dimensions and positions of the knurl portions 111L and 111R and the spacing portions 112L and 112R of the long film 100 so as to satisfy the requirements (R1) and (R2). For example, it is preferable to select and adopt values ​​within the above-described ranges that result in the desired first winding diameter difference ΔD1 and second winding diameter difference ΔD2.

[0078] Furthermore, the air layer thickness d that satisfies requirement (R3) ａｉｒ In order to obtain the above, it is preferable to form the convex portions 132 of an appropriate height according to the dimensions and positions of the knurl portions 111L and 111R and the spacing portions 112L and 112R, and to manufacture the film roll 1 by a method including the knurl touch winding method described later. ａｉｒ In contrast, in the present embodiment, since the knurl portions 111L and 111R can be prevented from piling up with each other as described above, the air layer thickness d ａｉｒ Therefore, the small air layer thickness d that satisfies the requirement (R3) can be ａｉｒ can be obtained.

[0079] <Method for manufacturing film roll 1> The above-mentioned film roll 1 can be manufactured by a manufacturing method including winding the long film 100 around the winding core 10 by a knurl touch winding method. In detail, the method for manufacturing the film roll 1 using the knurl touch winding method includes: a step (S2) of winding the long film 100 around a touch roll; and a step (S3) of winding the long film 100 wound around the touch roll onto the winding core 10 while bringing the touch roll into contact with the knurl regions 110L and 110R of the long film 100.

[0080] Furthermore, if the film to be wound does not have knurled portions, the manufacturing method for the film roll 1 may include, prior to step (S2), a step (S1) of forming knurled portions 111L and 111R in the long film before the knurled portions 111L and 111R are formed, thereby obtaining a long film 1 having the knurled portions 111L and 111R. Hereinafter, for the sake of distinction, the "long film before the knurled portions 111L and 111R are formed" may be referred to as the "film before processing." Below, the manufacturing method for the film roll 1, including steps (S1) to (S3), will be described with reference to the drawings.

[0081] Fig. 9 is a side view that schematically shows an apparatus for manufacturing a film roll 1 according to one embodiment of the present invention. As shown in Fig. 9, a typical method for manufacturing a film roll 1 involves winding up a long film 100 while continuously transporting the film in the film's longitudinal direction. In this embodiment, an example will be described in which a knurled portion (not shown in Fig. 9) is formed in a pre-processing film 400 by a processing device 410 to obtain a long film 100, and the long film 100 is then supplied to a touch roll 430 via a transport roll 420 and wound onto a winding core 10.

[0082] 9, the long unprocessed film 400 is transported in the longitudinal direction of the film as shown by arrow A9 and supplied to a processing device 410. Convex portions are formed on the unprocessed film 400 supplied to the processing device 410, and a long film 100 including knurled portions is obtained (step (S1)).

[0083] As the processing device 410, it is preferable to use a laser processing device capable of forming knurled portions by irradiating laser light, from the viewpoint of easily adjusting the height, pitch, and planar shape of the convex portions. When using a laser processing device, the laser light 411 is irradiated onto the unprocessed film 400 while moving the irradiation point where the laser light 411 hits the unprocessed film 400. At the point irradiated with the laser light 411, localized thermal melting or ablation occurs in the unprocessed film 400. Therefore, concave-convex portions 130 (see FIG. 3) can be formed at the point irradiated with the laser light 411 on the unprocessed film 400, thereby obtaining a long film 100 having knurled portions 111L and 111R.

[0084] During the irradiation of the laser light 411, the irradiation point where the laser light 411 strikes the unprocessed film 400 is moved so as to trace the planar shape of the desired uneven portion 130. As a result, the uneven portion 130 is formed along the trace of the movement of the irradiation point of the laser light 411, so that the uneven portion 130 having the desired planar shape can be formed.

[0085] The moving speed of the irradiation point of the laser beam 411 can be appropriately set within a range capable of forming the desired uneven portion 130. In one example, the range of the moving speed of the irradiation point of the laser beam 411 is preferably 500 mm / s or more, more preferably 1000 mm / s or more, even more preferably 1500 mm / s or more, and preferably 10000 mm / s or less, more preferably 9000 mm / s or less, even more preferably 8000 mm / s or less. The specific moving speed may be adjusted within the above range so as to obtain the uneven portion 130 having the convex portions 132 (see FIG. 3 ) of the desired height.

[0086] Examples of laser devices that irradiate laser light 411 include ArF excimer laser devices, KrF excimer laser devices, XeCl excimer laser devices, YAG laser devices (particularly, third or fourth harmonic), YLF or YVO4 solid-state laser devices (particularly, third or fourth harmonic), Ti:S laser devices, semiconductor laser devices, fiber laser devices, and carbon dioxide laser devices. Among these laser devices, carbon dioxide laser devices are preferred because they are relatively inexpensive and can efficiently provide an output suitable for film processing.

[0087] The range of the output power of the laser light is preferably 1 W or more, more preferably 5 W or more, even more preferably 15 W or more, and is preferably 120 W or less, more preferably 100 W or less, even more preferably 80 W or less, even more preferably 70 W or less. The specific output power may be adjusted within the above range so as to obtain the uneven portion 130 having the convex portions 132 of the desired height.

[0088] Processing by the processing device 410 described above forms knurled portions 111L and 111R in the unprocessed film 400, thereby obtaining the long film 100 to be wound up. This long film 100 is supplied to the touch roll 430 via the transport roll 420. The long film 100 supplied to the touch roll 430 is wound around the touch roll 430 (step (S2)).

[0089] The touch roll 430 is a roll having a length in the roll axis direction equal to or greater than the width of the long film 100, and is provided so as to be rotatable in the circumferential direction around its rotation axis (not shown). The touch roll 430 may be provided so as to be freely rotatable. If the touch roll 430 is provided so as to be freely rotatable, the touch roll 430 can rotate in the circumferential direction due to the frictional force applied by the long film 100 around which it is wound. The touch roll 430 may also be rotationally driven by a rotational driving force applied by a driving device (not shown). For example, if the frictional force between the touch roll 430 and the long film 100 is small or if the touch roll 430 is heavy, a rotational driving force may be applied to the touch roll 430 to an extent that mechanical loss can be reduced. The long film 100 wound around the touch roll 430 is guided to the winding core 10 by the rotating touch roll 430.

[0090] The core 10 is usually driven to rotate in the circumferential direction by a drive device (not shown). The long film 100, which has been wound around the touch roll 430 and guided to the core 10, is then wound onto the core 10 to obtain the film roll 1 (step (S3)).

[0091] 10 is a plan view schematically showing the state of the long film 100 being wound around the winding core 10 in the manufacturing method of the film roll 1 according to one embodiment of the present invention. As shown in Fig. 10, the long film 100 wound around the touch roll 430 is wound around the winding core 10 while the touch roll 430 is brought into contact with the knurl regions 110L and 110R of the long film 100 that has already been wound around the winding core 10 and has become part of the film roll 1 in the process of being manufactured.

[0092] During winding, the touch roll 430 preferably presses the film roll 1 in the radial direction of the winding core 10 toward the center of the winding core 10 with a specific load. For example, a biasing device such as an air cylinder may be provided on a support arm (not shown) supporting the touch roll 430, and the touch roll 430 may press the film roll 1 using the biasing device. This allows the knurl regions 110L and 110R of the long film 100 wound around the winding core 10 (i.e., the long film included in the film roll 1 in the manufacturing process) to be pressed toward the center of the winding core 10 with a specific load. This prevents air from being trapped between the overlapping knurl regions 110L and 110R. Therefore, by reducing the diameters of the first large diameter portion 210L and the second large diameter portion 210R around which the knurl regions 110L and 110R are wound, the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 that satisfy the requirements (R1) and (R2) can be obtained. Furthermore, it is usually possible to suppress winding misalignment by increasing the friction between the long film 100 at the first large diameter portion 210L and the second large diameter portion 210R.

[0093] Furthermore, the long film 100 wound around the touch roll 430 is wound onto the winding core 10 while the touch roll 430 does not come into contact with the flat regions 120 of the long film 100 that has already been wound onto the winding core 10 and become part of the film roll 1 in the process of being manufactured. This allows air to be effectively drawn into the spaces between the overlapping flat regions 120. Therefore, the air layer thickness d that satisfies requirement (R3) is ａｉｒ The thickness of the air layer d ａｉｒ can be adjusted by adjusting the height of the convex portions 132 (not shown in FIG. 10) of the knurl portions 111L and 111R. ａｉｒ The ability to adjust the temperature is one of the advantages of the touch roll winding method.

[0094] The magnitude of the load with which the touch roll 430 presses the film roll 1 during production is preferably set so that the touch roll 430 contacts the knurled regions 110L and 110R of the long film 100 wound around the winding core 10, but does not contact the flat region 120 of the long film 100 wound around the winding core 10. In one example, the range of the load is preferably 50 N / m or more, more preferably 60 N / m or more, even more preferably 70 N / m or more, and preferably 200 N / m or less, more preferably 180 N / m or less, and even more preferably 160 N / m or less. Here, the unit of the load, "N / m," represents the magnitude of the force applied per meter of width of the long film 100. The specific magnitude of the load is preferably selected from the above range so as to satisfy requirements (R1) to (R3).

[0095] The magnitude of the load with which the touch roll 430 presses the film roll 1 during production may be changed according to the winding diameter of the film roll 1 during production. In this case, for example, the magnitude of the load may be changed so as to gradually decrease, or so as to gradually increase, or a combination of these may be used.

[0096] When winding the long film 100 onto the winding core 10, the winding tension (film tension) of the long film 100 at the start of winding is preferably 10 N / m or more, more preferably 50 N / m or more, even more preferably 80 N / m or more, and preferably 200 N / m or less, more preferably 170 N / m or less, even more preferably 140 N / m or less.

[0097] When winding the long film 100 onto the winding core 10, the winding tension may be constant at the start of winding, or may be varied. For example, the tension may be gradually reduced from the winding tension Ts at the start of winding the long film 100 as winding progresses. If the winding tension at the end of winding the long film 100 is Te, the tension taper ratio (%) is preferably 5% or more, more preferably 10% or more, even more preferably 15% or more, and is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less. Here, the tension taper ratio (%) is expressed as "tension taper ratio (%) = (Ts - Te) / Ts × 100".

[0098] When winding the long film 100 onto the winding core 10, the winding speed (line speed) of the long film 100 is preferably in the range of 10 m / min or more, more preferably 20 m / min or more, even more preferably 30 m / min or more, and preferably 150 m / min or less, more preferably 125 m / min or less, and even more preferably 100 m / min or less. The above-described film roll 1 can be manufactured by winding the long film 100 at such a high speed, which can contribute to improving manufacturing efficiency.

[0099] <Modifications> The above-described film roll may be further modified. For example, step (S1) of the method for manufacturing a film roll may include oscillating the position where the knurl portion is formed in the film width direction.

[0100] FIG. 11 is a front view schematically illustrating a film roll 2 according to a modified example of the embodiment of the present invention. FIG. 12 is a plan view schematically illustrating an enlarged view of the vicinity of one end (first end) of a long film 500 according to a modified example of the embodiment of the present invention. The film roll 2 and long film 500 shown in FIGS. 11 and 12 are identical to the film roll 1 and long film 100 according to the above-described embodiment, except that the position of the concave-convex portion 130 is oscillated in the film width direction. As shown in FIGS. 11 and 12, when the position of the knurl portion 111L (and the knurl portion 111R; see FIG. 5) is oscillated in the film width direction, the positions of the knurl portions 111L and 111R of the wound long film 500 can be shifted in the roll axis direction, effectively preventing the knurl portions 111L and 111R from piling up. Therefore, the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 can be easily reduced.

[0101] The degree of oscillation is determined by the oscillation amount A. Ｏ The oscillation amount A can be expressed as follows: Ｏ represents the amplitude of oscillation in the film width direction. Ｏ The width W of each of the knurled portions 111L and 111R １１１Ｌ and W １１１Ｒ Ratio to (A Ｏ / W １１１Ｌ and A Ｏ / W １１１Ｒ The range of the oscillation amount A is preferably 0.5 or more, more preferably 0.6 or more, and is preferably 1.0 or less, more preferably 0.8 or less. Ｏ may be selected from the above ranges so as to obtain the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 that satisfy the requirements (R1) and (R2).

[0102] When the oscillation is performed, it is preferable to appropriately set the oscillation period so as to obtain the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 that satisfy the requirements (R1) and (R2). For example, the oscillation period may be in the range of 800 mm to 1500 mm. Here, the oscillation period refers to the distance in the longitudinal direction of a long film in which knurls are formed while being transported, from when a knurl is formed at a certain position in the film width direction, until the position of the knurl is changed by oscillation and the knurl is again formed in the original position.

[0103] In the above-described embodiment, an example in which one uneven portion is formed in one knurl portion has been shown, but two or more uneven portions may be formed in one knurl portion.

[0104] In the above-described embodiment, an example was shown in which the knurl portion was formed as an uneven portion including a combination of recesses and protrusions, but the knurl portion may be formed as a protrusion without a recess.

[0105] Although the above-described embodiment shows an example in which the protrusions are formed using laser light, the protrusions may be formed by other methods, such as embossing using heat and pressure.

[0106] <Composition and Layer Structure of Long Film> As the long film described above, a resin film is usually used. This resin film may be a stretched film or an unstretched film. In addition, the resin film may be a single-layer film having only a base layer, or a multi-layer film having an optional layer in combination with the base layer.

[0107] The substrate layer is usually a layer formed of a resin. Various resins can be used as such a resin depending on the application of the long film, but cycloolefin resin is preferred. Films having a substrate layer formed of a cycloolefin resin generally tend to entrap air during winding, and therefore tend to have poor winding properties. In contrast, the long film according to the above-described embodiment can be well wound by the Touchnar winding method.

[0108] A cycloolefin resin is a resin containing a cycloolefin polymer. The cycloolefin polymer is excellent in mechanical properties, heat resistance, transparency, low moisture absorption, dimensional stability, and light weight. The cycloolefin polymer refers to a polymer whose structural unit has an alicyclic structure. The cycloolefin polymer may be a polymer having an alicyclic structure in the main chain, a polymer having an alicyclic structure in the side chain, a polymer having alicyclic structures in the main chain and the side chain, or a mixture of two or more of these in any ratio. Among these, from the viewpoint of mechanical strength and heat resistance, a polymer having an alicyclic structure in the main chain is preferred.

[0109] Examples of the alicyclic structure include saturated alicyclic hydrocarbon (cycloalkane) structures and unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structures. Among these, from the viewpoints of mechanical strength and heat resistance, cycloalkane structures and cycloalkene structures are preferred, and cycloalkane structures are particularly preferred.

[0110] The number of carbon atoms constituting each alicyclic structure is preferably 4 or more, more preferably 5 or more, and preferably 30 or less, more preferably 20 or less, and particularly preferably 15 or less. When the number of carbon atoms constituting the alicyclic structure is within this range, the mechanical strength, heat resistance, and moldability of the resin are well balanced.

[0111] In the cycloolefin polymer, the proportion of structural units having an alicyclic structure is preferably 55% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the proportion of structural units having an alicyclic structure in the cycloolefin polymer is within this range, transparency and heat resistance are improved.

[0112] Examples of cycloolefin polymers include norbornene polymers, monocyclic cycloolefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and hydrogenated versions thereof. Among these, norbornene polymers and hydrogenated versions thereof are particularly preferred due to their good moldability.

[0113] Examples of norbornene polymers and their hydrogenated products include ring-opening polymers of monomers having a norbornene structure and their hydrogenated products; and addition polymers of monomers having a norbornene structure and their hydrogenated products. Examples of ring-opening polymers of monomers having a norbornene structure include ring-opening homopolymers of one type of monomer having a norbornene structure, ring-opening copolymers of two or more types of monomers having a norbornene structure, and ring-opening copolymers of a monomer having a norbornene structure and any monomer copolymerizable therewith. Examples of addition polymers of monomers having a norbornene structure include addition homopolymers of one type of monomer having a norbornene structure, addition copolymers of two or more types of monomers having a norbornene structure, and addition copolymers of a monomer having a norbornene structure and any monomer copolymerizable therewith. Among these, hydrogenated ring-opening polymers of monomers having a norbornene structure are particularly suitable from the viewpoints of moldability, heat resistance, low moisture absorption, dimensional stability, light weight, etc.

[0114] The weight average molecular weight (Mw) of the cycloolefin polymer is preferably 10,000 or more, more preferably 15,000 or more, particularly preferably 20,000 or more, and is preferably 100,000 or less, more preferably 80,000 or less, particularly preferably 50,000 or less. When the weight average molecular weight is within the above range, the mechanical strength and moldability of the resin are well balanced.

[0115] The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the cycloolefin polymer is preferably 1.2 or more, more preferably 1.5 or more, particularly preferably 1.8 or more, and preferably 3.5 or less, more preferably 3.0 or less, particularly preferably 2.7 or less. When the molecular weight distribution is at least the lower limit of the above range, the productivity of the polymer can be increased and the production cost can be reduced. On the other hand, when it is at most the upper limit, the amount of low-molecular-weight components is reduced, thereby suppressing relaxation during exposure to high temperatures and improving the stability of the film.

[0116] The weight-average molecular weight and number-average molecular weight are polyisoprene- or polystyrene-equivalent weight-average molecular weights measured by gel permeation chromatography using cyclohexane as a solvent, although toluene may be used as the solvent in the gel permeation chromatography if the sample is insoluble in cyclohexane.

[0117] The glass transition temperature of the cycloolefin polymer is preferably 130° C. or higher, more preferably 135° C. or higher, and preferably 150° C. or lower, more preferably 145° C. or lower. When the glass transition temperature is equal to or higher than the lower limit of the above range, the durability of the film at high temperatures can be improved. When the glass transition temperature is equal to or lower than the upper limit of the above range, stretching can be easily performed.

[0118] As the cycloolefin polymer, for example, those described in WO 2017 / 145718 can be used.

[0119] The proportion of the cycloolefin polymer in the cycloolefin resin is preferably 50% by weight to 100% by weight, more preferably 70% by weight to 100% by weight, and particularly preferably 90% by weight to 100% by weight. When the proportion of the polymer is within this range, sufficient heat resistance and transparency can be obtained.

[0120] The cycloolefin resin may contain any component other than the cycloolefin polymer in combination with the cycloolefin polymer. Examples of the optional component include colorants such as pigments and dyes; fluorescent brighteners; dispersants; heat stabilizers; light stabilizers; ultraviolet absorbers; antistatic agents; antioxidants; lubricants; etc. These may be used alone or in combination of two or more.

[0121] The substrate layer can be produced by molding a resin using an appropriate film molding method. Examples of film molding methods include cast molding, extrusion molding, and inflation molding. Among them, the melt extrusion method, which does not use a solvent, can efficiently reduce the amount of residual volatile components, and is preferred from the viewpoints of the global environment, working environment, and excellent production efficiency. As the melt extrusion method, an inflation method using a die may be used, but the T-die method is preferred from the viewpoints of excellent productivity and thickness accuracy.

[0122] When a multilayer film having two or more layers is used as a long film, the multilayer film preferably has a base layer and a functional layer. The functional layer may be provided on one side of the base layer or on both sides. In particular, the functional layer is preferably provided on the knurled portion side of the base layer, and more preferably, the knurled portion is provided on the surface of the functional layer. Examples of such functional layers include an antistatic layer, a hard coat layer, an anti-adhesion layer, and an easy-adhesion layer.

[0123] The antistatic layer refers to a layer having a small surface resistance value. The specific surface resistance value of the antistatic layer is preferably 1.0×10 ６ Ω / □ or more, more preferably 1.0×10 ７ Ω / □ or more, particularly preferably 1.0×10 ８ Ω / □ or more, preferably 1.0×10 １０ Ω / □ or less, more preferably 5.0×10 ９ Ω / □ or less, particularly preferably 1.0×10 ９ The surface resistance is Ω / □ or less. The surface resistance can be measured in accordance with JIS K6911 using a digital ultra-insulation / microcurrent meter ("DSM-8104" manufactured by Hioki Electric Industry Co., Ltd.). Such an antistatic layer can be formed, for example, from a resin containing conductive particles such as metal oxide particles and a polymer.

[0124] The hard coat layer refers to a layer having high hardness. Specifically, the hardness of the hard coat layer is preferably B or higher, more preferably HB or higher, and particularly preferably H or higher, as measured by the JIS pencil hardness scale. Here, the JIS pencil hardness is the hardness of a pencil at which scratches begin to appear when the surface of the layer is scratched with a pencil of various hardness tilted at a 45° angle and a load of 500 g is applied from above, in accordance with JIS K5600-5-4. Such a hard coat layer can be formed, for example, from a resin.

[0125] The adhesion prevention layer is a layer having a rough surface that can prevent adhesion between films when the film is laminated with another film. Such an adhesion prevention layer can be formed, for example, from a resin containing a polymer and particles.

[0126] The adhesive layer is a layer that exhibits high adhesiveness when the surface of the adhesive layer is bonded to another member. Such an adhesive layer can be formed, for example, from a resin containing a polymer.

[0127] Among the functional layers, the easy-adhesion layer is preferred. The easy-adhesion layer is preferably a layer containing an aqueous resin. The aqueous resin refers to a resin that can be prepared as a solution or dispersion using water as a medium. A layer of the aqueous resin can be formed on the surface of the substrate layer by applying an aqueous solution or aqueous dispersion containing the aqueous resin to the surface of the substrate layer and drying it. Examples of the aqueous resin include urethane resin, polyester resin, and emulsions of each resin, and preferably, aqueous urethane resin.

[0128] As the functional layer, for example, those described in WO 2017 / 145718 can be used.

[0129] <Uses of Film Roll> The film roll produced by the above-described production method can be used for storing and transporting a wide range of films, such as optical films, moisture-proof films, packaging films, conductive films, insulating films, antistatic films, barrier films, and films for wiring boards. In particular, it is preferable to apply it to optical films, from the viewpoint of effectively utilizing the advantage of being able to suppress defects. Examples of optical films include retardation films, protective films for polarizing plates, polarizing films, brightness-enhancing films, light-diffusing films, light-collecting films, and reflective films.

[0130] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples shown below, and can be practiced with any modifications within the scope of the claims of the present invention and their equivalents. In the following description, "%" and "parts" representing amounts are by weight unless otherwise specified. Furthermore, the operations described below were carried out in air at room temperature and normal pressure (23°C, 1 atm) unless otherwise specified.

[0131] <Explanation of measurement method> (Method for measuring the height H of the convex portions of the knurled portions) The height of the convex portions formed on the film was measured using a Digimatic micrometer (manufactured by Mitutoyo Corporation). Specifically, a flat area where no convex portions were formed was clamped with the micrometer and zero-point correction was performed. Then, the knurled portion where the convex portions were formed was clamped with the micrometer and the measured value was obtained as the height of the convex portions. In the examples and comparative examples described below, the knurled portions were formed under the same conditions at both ends of the film in the width direction, so the height of the convex portions was measured at 50 points on each end of one side in the film width direction, for a total of 100 knurled portions at both ends, and the arithmetic average value was used as the height of the convex portions of the film.

[0132] (Method for Measuring Winding Diameter Differences ΔD1 and ΔD2 of a Film Roll) As shown in FIG. 6 , laser displacement meters (Keyence Corporation, "LJ-X8400") 300L and 300R were installed facing the film roll 1 at positions away from the outermost surface 1S of the film roll 1. The laser displacement meters 300L and 300R were installed so that the optical axes 310L and 310R of measurement laser beams (not shown) emitted from the laser displacement meters 300L and 300R were perpendicular to the central axis 10A of the winding core 10. The distance from the laser displacement meters 300L and 300R to the surface of the winding core 10 was set to 580 mm. While the film roll 1 was rotated in the circumferential direction around the central axis 10A of the winding core 10, the laser displacement meters 300L and 300R measured the distance from the laser displacement meters 300L and 300R to the outermost surface 1S of the film roll 1 at a sampling period of 50 ms. The above measurement was carried out in a measurement range of 100 mm width at both ends of the film roll 1 in the roll axis direction, and a shape profile was obtained. From the shape profile thus obtained, the maximum diameter D of the first large diameter portion 210L was calculated. Ｎ１（ＭＡＸ） , the average diameter D of the small diameter portion 220 on the first large diameter portion 210L side Ｆ１（ＡＶＥ） , the maximum diameter D of the second large diameter portion 210R Ｎ２（ＭＡＸ） , the average diameter D of the small diameter portion 220 on the second large diameter portion 210R side Ｆ２（ＡＶＥ） The first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 were calculated based on the formulas (1) and (2).

[0133] (The thickness of the air layer between the film rolls included in the film rolls d ａｉｒMeasurement method of (a) (b) As shown in FIG. 7 , a long-distance laser displacement meter (Keyence Corporation, "LK-G500") 300L was installed facing the film roll 1 at a position away from the outermost peripheral surface 1S of the film roll 1. The laser displacement meter 300L was installed so that the optical axes 310L and 310R of the measurement laser light emitted from the laser displacement meter 300L were perpendicular to the central axis 10A of the winding core 10. The distance from the laser displacement meter 300L to the surface of the winding core 10 was set to 580 mm. While the film roll 1 was rotated in the circumferential direction around the central axis 10A of the winding core 10, the laser displacement meter 300L measured the distance from the laser displacement meter 300L to the outermost peripheral surface 1S of the film roll 1 at the center in the roll axis direction of the film roll 1, thereby obtaining a shape profile of the film roll 1. From the shape profile thus obtained, the average radius Rb of the film roll 1 at the center in the roll axis direction was obtained.

[0134] Thereafter, the film was unwound from the film roll, and a test piece was cut out with scissors from the center of the film width direction, measuring 50 mm in width and one circumference of the film roll. The thickness of this test piece was measured using a desktop thickness meter ("Rotary Caliper Meter RC-1" manufactured by Meisan Co., Ltd.), and the average value of the thickness of one circumference of the film roll was taken as the film thickness d ｆｉｌｍ was obtained as.

[0135] The average radius Rb of the film roll 1 and the film thickness d ｆｉｌｍ , and the average radius Ra of the winding core 10 and the film length L, which have been measured in advance, are used to calculate the air layer thickness d based on the formulas (M3) and (M4). ａｉｒ was calculated.

[0136] (Method for evaluating gauge bands on film rolls) After winding, the film rolls were stored for 14 days in an environment with a temperature of 20°C to 25°C and a humidity of 50% RH to 70% RH. After that, a high-intensity lamp was irradiated onto the end of the film roll in the roll axis direction, and the circumferential surface of the film roll was observed. Localized band-shaped defects extending in the circumferential direction of the roll were detected as gauge bands.

[0137] The surface roughness of the gauge bands detected by the above method was measured using a small surface roughness measuring instrument (Mitutoyo Corporation "SURFTEST SJ-410 series"). Since the gauge bands extend in the circumferential direction of the roll, they can be measured at any circumferential position of the roll. A surface roughness profile in the axial direction of the roll was obtained for the gauge band occurrence location. The range of the film roll surface shape was calculated from the measurement data for the gauge band occurrence location. The "range" above represents the difference between the maximum and minimum heights of the film roll surface in the gauge band (maximum value - minimum value). Based on the range, gauge band defects were evaluated according to the following criteria. The larger the range, the greater the difference between the high parts (peaks) and low parts (valleys) in the gauge band, making it easier for defects to form. "A": Range is 0.15 mm or less "B": Range is greater than 0.15 mm and 0.3 mm or less "C": Range is greater than 0.3 mm

[0138] (Method for Evaluating Imitation Defects in Long Film Included in Film Roll) After winding, the film roll was stored for 14 days in an environment with a temperature of 20°C to 25°C and a humidity of 50% to 70% RH. The film was then unwound from the film roll at a line speed of 50 m / min. The total number of defects in the unwound film was counted using a defect detector. In this case, defects detected within a 50 mm width at each end of the film width direction were excluded to distinguish them from edge defects occurring near the knurled region, and defects detected in other flat regions were counted as "imitation defects." The defect detector was set up to illuminate using a specular reflection method, and was set up so that buckling on the film could be detected by a change in the light reflection state. In this inspection, a defect with a depth of 3 μm to 5 μm and a width of 3 mm to 5 mm was counted as one defect. Based on the detection results, the occurrence of minute defects was evaluated according to the following criteria: "A": The total number of defects was 0.1 / m. ２ "B": The total number of defects is 0.1 / m or less. ２ Larger than 1.0 pieces / m ２ "C": The total number of defects is 1.0 / m or less. ２ Greater than.

[0139] (Method for evaluating edge defects in long film contained in film roll) Using the same method as described above (Method for evaluating small particle defects in long film contained in film roll), the film roll was stored, the film was unwound, and the total number of defects in the unwound film was counted using a defect detector. In this case, to distinguish from small particle defects, defects detected within a 50 mm width range at both ends of the film width direction were counted as "edge defects." In this inspection, defects with a depth of 3 μm to 5 μm and a width of 3 mm to 5 mm were detected as one defect. Based on the detection results, the edge defects were evaluated according to the following criteria: "A": The total number of defects was 0.1 / m ２ "B": The total number of defects is 0.1 / m or less. ２ Larger than 1.0 pieces / m ２ "C": The total number of defects is 1.0 / m or less. ２ Greater than.

[0140] Example 1 (1) Production of substrate layer: Pellets of an alicyclic structure-containing polymer resin (ZEONOR1215 manufactured by Zeon Corporation) were dried for 5 hours at 100° C. The pellets were fed into an extruder, melted in the extruder, passed through a polymer pipe and a polymer filter, and extruded from a T-die onto a casting drum in the form of a sheet. The sheet was then cooled to obtain a long substrate layer having a thickness of 80 μm and a width of 1600 mm.

[0141] (2) Formation of easy-adhesion layer: 100 parts of an aqueous dispersion of polyether polyurethane (Superflex 870 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) in terms of polyurethane amount, 15 parts of an epoxy compound (Denacol EX313 manufactured by Nagase ChemteX Corporation) as a crosslinking agent, 8 parts of an aqueous dispersion of silica particles (Snowtex MP1040 manufactured by Nissan Chemical Industries, Ltd.; average particle size 120 nm) in terms of silica particles amount and 8 parts of an aqueous dispersion of silica particles (Snowtex XL manufactured by Nissan Chemical Industries, Ltd.; average particle size 50 nm) in terms of silica particles amount as a lubricant, 0.5 wt % of an acetylene surfactant (Surfynol 440 manufactured by Air Products and Chemicals Co., Ltd.) as a wetting agent based on the total solid content, and water were blended to obtain an aqueous dispersion of a liquid aqueous urethane resin with a solid content concentration of 2%. The aqueous dispersion of the aqueous urethane resin was applied to one surface of the base layer and dried to form an easy-adhesion layer having a thickness of 45 nm, thereby obtaining a long pre-stretched film including the base layer and the easy-adhesion layer.

[0142] (3) Film stretching: The long unstretched film was subjected to simultaneous biaxial stretching in the film longitudinal direction and film width direction at a stretching temperature of 135°C. The stretching ratio in the film longitudinal direction was 1.15 times, and the stretching ratio in the film width direction was 1.44 times. By this simultaneous biaxial stretching, a long stretched film having a thickness of 52 µm and a width of 1,490 mm was obtained.

[0143] (4) Formation of knurled portions: A 9.4 μm laser was used to form knurled portions on both ends of the long stretched film on the surface of the easy-adhesion layer side. ２A knurled portion having convex portions was formed by irradiating a laser beam. Specifically, a region (knurled region) within 10 mm of the edge of the stretched film in the film width direction was irradiated with laser beam in a manner to trace the shape shown in FIG. 4, forming a convex portion including convex portions (3 μm high) formed by the resin fluidized by the laser beam and concave portions formed by the resin being removed by thermal melting or ablation by the laser beam. The convex portion had a polygonal planar shape as shown in FIG. 4, with a dimension in the film longitudinal direction (corresponding to the length of the knurled portion) of 1.9 mm and a dimension in the film width direction (corresponding to the width of the knurled portion) of 9.4 mm. The convex portions were formed so as to be aligned in the film longitudinal direction at a pitch of 50 mm. Thus, in the knurled regions at both ends of the stretched film, knurled portions having convex portions were formed alternately with gap portions in the film longitudinal direction at a pitch of 50 mm.

[0144] (5) Film Winding: A 6000 m long stretched film with a knurled portion formed thereon was wound around a touch roll, and the stretched film was then wound around a cylindrical core at a winding speed of 50 m / min to obtain a film roll. This winding was performed so that the touch roll contacted the knurled region of the stretched film wound around the core, but did not contact the flat region of the stretched film wound around the core (knurled touch winding method). The winding tension at the start of winding was 120 N / m, and as winding progressed, the winding tension was gradually reduced at a tension taper ratio of 20%. The load (touch pressure) with which the touch roll pressed the film roll during production was 100 N / m. The obtained film roll was evaluated using the method described above.

[0145] Example 2: In step (4), CO ２ The film roll was manufactured and evaluated in the same manner as in Example 1, except that the output of the laser light was changed to change the height of the convex portions included in the uneven portion to 1 μm and the pitch of the uneven portion (i.e., the pitch of the knurled portion) to 30 mm.

[0146] Example 3: In step (4), CO ２The film roll was manufactured and evaluated in the same manner as in Example 1, except that the output of the laser light was changed to change the height of the convex portions included in the uneven portion to 7 μm and the pitch of the uneven portion (i.e., the pitch of the knurled portion) to 80 mm.

[0147] Example 4 A film roll was produced and evaluated in the same manner as in Example 1, except that in step (5), the winding speed was changed to 80 m / min and the load (touch pressure) with which the touch roll pressed the film roll during production was changed to 200 N / m.

[0148] Example 5: In step (4), CO ２ The output of the laser light was changed to change the height of the convex portions included in the concave-convex portion to 7 μm. Also, in step (5), the load (touch pressure) with which the touch roll presses the film roll in the middle of production was changed to 50 N / m. Except for the above, the film roll was produced and evaluated in the same manner as in Example 1.

[0149] Example 6 In step (3), the stretching ratio in the longitudinal direction of the film was changed to change the thickness of the stretched film to 23 μm. Furthermore, in step (4), the pitch of the concave-convex portions (i.e., the pitch of the knurled portions) was changed to 30 mm. Furthermore, in step (5), the length of the stretched film to be wound up was changed to 9000 m, and the winding tension at the start of winding was changed to 100 N / m. Except for the above, a film roll was produced and evaluated in the same manner as in Example 1.

[0150] Example 7: In step (4), CO ２ The output of the laser light was changed to change the height of the convex portions included in the uneven portion to 9 μm, and the pitch of the uneven portion (i.e., the pitch of the knurled portion) was changed to 100 mm. Also, in step (5), the winding speed was changed to 100 m / min, and the load (touch pressure) with which the touch roll presses the film roll during production was changed to 150 N / m. Except for the above, the film roll was produced and evaluated in the same manner as in Example 1.

[0151] Example 8: In step (4), CO ２The output of the laser light was changed to change the height of the convex portions included in the uneven portion to 7 μm. Furthermore, at both ends in the width direction of the film, the irradiation position of the laser light was oscillated in the width direction of the film with an oscillation amount of 10 mm and a cycle of 1000 mm. Furthermore, in step (5), the load (touch pressure) with which the touch roll presses the film roll during production was changed to 50 N / m. Except for the above, the film roll was produced and evaluated in the same manner as in Example 1.

[0152] Comparative Example 1 In step (4), the pitch of the concave-convex portions (i.e., the pitch of the knurled portions) was changed to 10 mm. In addition, the length of the stretched film to be wound in step (5) was changed to 5,200 m. Except for the above, a film roll was produced and evaluated in the same manner as in Example 1.

[0153] Comparative Example 2: In step (4), CO ２ The output of the laser beam was changed to change the height of the convex portions included in the uneven portion to 5 μm, and the pitch of the uneven portion (i.e., the pitch of the knurled portion) was changed to 200 mm. Furthermore, the length of the stretched film to be wound in step (5) was changed to 5,200 m. Except for the above, the film roll was produced and evaluated in the same manner as in Example 1.

[0154] Comparative Example 3: In step (4), CO ２ The output of the laser light was changed to change the height of the convex portions included in the concave-convex portion to 7 μm, and the pitch of the convex-convex portions (i.e., the pitch of the knurled portions) to 3 mm. Furthermore, the winding method of the stretched film in step (5) was changed to gap winding. The gap winding method in step (5) was performed as follows.

[0155] A 3900 m long stretched film with a knurled portion was wound around a gap roll, and then the stretched film was wound around a cylindrical core at a winding speed of 50 m / min to obtain a film roll. This winding was performed so that the gap roll did not come into contact with the stretched film wound around the core (gap winding method). The winding tension at the start of winding was 160 N / m, and as winding progressed, the winding tension was gradually reduced at a tension taper ratio of 30%. The obtained film roll was evaluated using the methods described above.

[0156] Comparative Example 4: In step (4), CO ２ The output of the laser light was changed to change the height of the convex portions included in the uneven portion to 7 μm, and the pitch of the uneven portion (i.e., the pitch of the knurled portion) to 5 mm. In addition, the length of the stretched film to be wound in step (5) was changed to 5,200 m, the tension taper ratio was changed to 30%, and the load (touch pressure) with which the touch roll presses the film roll during production was changed to 20 N / m. Except for the above, the film roll was produced and evaluated in the same manner as in Example 1.

[0157] Comparative Example 5: In step (4), CO ２ The output of the laser light was changed to change the height of the convex portions included in the uneven portion to 7 μm, and the pitch of the uneven portion (i.e., the pitch of the knurled portion) to 5 mm. In addition, the length of the stretched film to be wound in step (5) was changed to 5,200 m, the winding speed was changed to 80 m / min, the tension taper ratio was changed to 30%, and the load (touch pressure) with which the touch roll presses the film roll during production was changed to 20 N / m. Except for the above, the film roll was produced and evaluated in the same manner as in Example 1.

[0158] Comparative Example 6: In step (4), CO ２The output of the laser light was changed to change the height of the convex portions included in the uneven portion to 13 μm, and the pitch of the uneven portion (i.e., the pitch of the knurled portion) to 3 mm. In addition, the length of the stretched film to be wound in step (5) was changed to 5,200 m, the tension taper ratio was changed to 30%, and the load (touch pressure) with which the touch roll presses the film roll during production was changed to 20 N / m. Except for the above, the film roll was produced and evaluated in the same manner as in Example 1.

[0159] Comparative Example 7 In the step (4), the method for forming the concave and convex portions was ２ The laser processing using laser light was changed to a thermal embossing process using a heated mold. The height of the convex portions included in the formed uneven portion was 1.5 μm, the dimension in the longitudinal direction of the film (corresponding to the length of the knurled portion) was 0.1 mm, the dimension in the width direction of the film (corresponding to the width of the knurled portion) was 10 mm, and the pitch of the uneven portions (i.e., the pitch of the knurled portion) was 1 mm. In addition, the length of the stretched film to be wound in step (5) was changed to 5200 m, and the load (touch pressure) with which the touch roll presses the film roll during production was changed to 115 N / m. Except for the above, the film roll was produced and evaluated in the same manner as in Example 1.

[0160] <Results> The results of the above-mentioned Examples and Comparative Examples are shown in the table below. In the table below, the meanings of abbreviations are as follows: "Touch" in the "Winding method" column: knurl touch winding method. "Gap" in the "Winding method" column: gap winding method. "L" in the "Knurl processing method" column: laser processing. "Heat" in the "Knurl processing method" column: thermal embossing. "Knurl height": height of the convex portion of the knurl portion. "Knurl pitch": pitch of the knurl portion. "Oscillation amount": amount of oscillation of the knurl portion in the film width direction.

[0161]

[0162]

[0163] 1 Film roll 2 Film roll 10 Winding core 10A Central axis of winding core 10S Peripheral surface of winding core 100 Long film 100U Surface of long film 110L, 110R Knurl region 111L, 111R Knurl portion 112L, 112R Spacing portion 120 Flat region 130 Concave and convex portion 131 Concave portion 132 Convex portion 133 Corner portion 134, 135 Straight portion 140L, 140R Edge 210L First large diameter portion 210R Second large diameter portion 220 Small diameter portion 221L, 221R Measurement range within small diameter portion 230 Boundary portion 300L, 300R Laser displacement meter 310L, 310R Optical axis of laser light 400 Unprocessed film 410 Processing device 411 Laser light 420 Transport roll 430 Touch roll 500 Long film

Claims

1. A film roll having a core and a long film wound around the core; the long film includes two knurled regions including a plurality of convex portions provided at both ends in the film width direction, and a flat region provided between the two knurled regions; the film roll includes two large diameter portions around which the knurled regions of the long film are wound, and a small diameter portion between the two large diameter portions around which the flat region of the long film is wound; a first winding diameter difference ΔD1 represented by the following formula (1) and a second winding diameter difference ΔD2 represented by the following formula (2) are both smaller than 0.3 mm, and at least one of the first winding diameter difference ΔD1 and the second winding diameter difference ΔD2 is 0.05 mm or more; and the thickness of the air layer between the long films wound at the center of the roll axis direction of the film roll is 0.9 μm or more and 2.0 μm or less. (In formula (1), D Ｎ１（ＭＡＸ） represents the maximum value of the diameter of one of the two large diameter portions of the film roll, and D Ｆ１（ＡＶＥ） represents the average diameter of the small diameter portion on the one large diameter portion side of the film roll, and in formula (2), D Ｎ２（ＭＡＸ） represents the maximum value of the diameter of the other of the two large diameter portions of the film roll, and D Ｆ２（ＡＶＥ） represents the average value of the diameter of the small diameter portion on the other large diameter portion side of the film roll.) 2. The film roll according to claim 1, wherein the knurl region of the long film alternates between knurl portions having the convex portions and spaced portions not having the convex portions in the longitudinal direction of the film; and the pitch of the knurl portions in the longitudinal direction of the film is 20 mm or more and 100 mm or less.

3. The film roll according to claim 1, wherein the height of the protrusions is 1 μm or more and 10 μm or less.

4. The film roll according to claim 1, wherein the long film comprises a cycloolefin polymer.

5. The film roll according to claim 1, wherein the length of the long film is 2,000 m or more and 10,000 m or less.

6. A method for manufacturing a film roll having a winding core and a long film wound around the winding core; the long film includes two knurl regions including a plurality of convex portions provided at both ends in the film width direction, and a flat region provided between the two knurl regions; the knurl regions of the long film include knurl portions having the convex portions and spaced portions not having the convex portions, which are arranged alternately in the longitudinal direction of the film; the pitch of the knurl portions in the longitudinal direction of the film is 20 mm or more and 100 mm or less; the method for manufacturing a film roll includes the steps of: winding the long film around a touch roll; and winding the long film wound around the touch roll onto the winding core while bringing the touch roll into contact with the knurl regions of the long film.

7. The method for producing a film roll according to claim 6, further comprising a step of forming the knurled portion in an unprocessed film to obtain the long film.

8. The method for producing a film roll according to claim 7, further comprising forming the knurled portion by irradiation with laser light.

9. A method for manufacturing a film roll as described in claim 7, wherein the process of forming the knurl portion in the unprocessed film includes oscillating the formation position of the knurl portion in the width direction of the film; and the ratio of the amount of oscillation of the knurl portion to the width of one knurl portion is 0.5 or more and 1.0 or less.

10. The method for producing a film roll according to claim 6, wherein the height of the convex portions is 1 μm or more and 10 μm or less.

11. The method for producing a film roll according to claim 6, wherein the long film comprises a cycloolefin polymer.

12. The method for producing a film roll according to claim 6, wherein the length of the long film to be wound is 2,000 m or more and 10,000 m or less.

13. The method for manufacturing a film roll according to claim 6, wherein the axial length of the touch roll is equal to or greater than the width of the long film, and in the step of winding the long film around the core, the touch roll presses the film roll in the process of being manufactured toward the center of the core with a load of 50 N / m to 200 N / m.

14. The method for producing a film roll according to claim 6, wherein the winding speed of the long film is 10 m / min or more and 150 m / min or less.

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