Long film and method for manufacturing the same

Abstract

A continuous film having, in at least one surface thereof, a plurality of knurled regions which, when viewed from the thickness direction of the film, include linear protrusions arranged consecutively, wherein the knurled regions are formed side by side along the machine direction of the film and the positions of the highest points and / or the lowest points of the protrusions of the respective knurled regions are distributed in the transverse direction of the film.

Description

Technical Field

[0001] The present invention relates to a long film having a narl part and a method for manufacturing the same.

Background Art

[0002] Conventionally, films such as optical films have been manufactured as long films from the viewpoint of achieving high productivity. However, since films are generally thin, they may be inferior in handling properties. Therefore, conventionally, it has been proposed to form a plurality of narl parts including convex parts in the longitudinal direction at the end parts in the width direction of the film to improve the handling properties of the film (Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] During manufacturing, a long film is generally continuously conveyed in its longitudinal direction, subjected to various processes, and then wound into a roll and shipped. Usually, when a long film is wound to obtain a roll, an air layer can be formed between the wound long films. Specifically, the long films support each other at the narl part, and an air layer can be formed at a part other than the narl part. In an area where this air layer exists, the wound long films can be non-contact with each other.

[0005] When the air layer is thin, long films may come into contact with each other, causing their surfaces to stick together. This phenomenon, where overlapping long films in a roll stick together, is sometimes called "blocking." For example, rolls are sometimes stored with their axial direction horizontal. In this case, the roll experiences compressive stress in the axial direction due to its own weight. This stress deforms the roll's shape, creating areas where the air layer is locally thin, which can lead to blocking.

[0006] Furthermore, if the aforementioned stress attempting to compress the roll in the axial direction becomes large, buckling may occur on the circumferential surface of the roll. "Buckling" of a roll refers to a depression formed when the roll partially indents radially. This buckling is more likely to occur in areas where the air layer between the stacked long films is thick. In these buckled areas, the long film may deform, and wrinkles may form.

[0007] Conventionally, the protrusions on the knurled portion were generally formed in a dot-like pattern when viewed from the thickness direction. However, when the protrusions are dot-like, the area of ​​support between the overlapping long films is small. Therefore, it may not be possible to stably resist the stress that tries to compress it in the axial direction, and blocking and wrinkle formation may not be suppressed.

[0008] Therefore, the inventor attempted to form the knurled protrusions in a linear shape that is not parallel to the longitudinal direction of the film when viewed from the film thickness direction. When the protrusions are formed in a linear shape, the long films can support each other over a larger area than when the protrusions are dot-shaped. As a result, the long films can resist the stress that tries to compress them in the axial direction with a large frictional force, thereby suppressing deformation. Consequently, it became possible to stably suppress the occurrence of blocking and wrinkles.

[0009] Furthermore, conventional knurled sections were generally formed by pressing with a pressing tool such as a pressing roll having an uneven surface. However, the raised parts of the knurled sections formed by pressing tended to retain significant stress. As a result, the height of the raised parts could change over time due to the relaxation of the aforementioned stress (stress remaining in the raised parts). When the height of the raised parts changes over time, blocking and wrinkling are more likely to occur as time passes.

[0010] Therefore, as a method to reduce the stress remaining in the convex portion, the inventor focused on a method of forming the knurled portion by laser light or inkjet printing. In the laser beam method, the material heated by the laser beam becomes fluid and deforms, forming a protrusion. This laser beam method allows for the formation of a protrusion without the use of mechanical forces such as pressing pressure. Therefore, typically, no significant stress remains in the protrusion. Furthermore, in inkjet printing methods, the printed ink can accumulate and form raised areas. Since the raised areas are formed by the accumulation of ink, no mechanical force such as pressing force is required for their formation. Therefore, normally, no significant stress remains in the raised areas. Therefore, the height of the protrusions formed by laser light or inkjet printing is suppressed over time.

[0011] In the aforementioned methods such as laser light or inkjet printing, a knurled area including a linear protrusion is typically formed by moving the knurled area forming device linearly along a long film at a drawing point. Here, the drawing point refers to the point where the knurled area forming device forms the protrusion. For example, in the method using laser light, the drawing point refers to the point where the laser light strikes the film. In the method using inkjet printing, the drawing point refers to the point where the ink strikes the film.

[0012] However, when the knurled portion was formed by the method described above, the convex portion of the linearly formed knurled portion sometimes had locally varying heights at certain positions in the film width direction. That is, at certain positions in the film width direction, the convex portion sometimes had locally higher or lower sections. In this case, in a roll containing a long roll of film that had been wound together, these locally varying height sections overlapped, amplifying the aforementioned localized height differences. Therefore, when locally higher sections overlapped, the long rolls of film would come into contact with each other under greater pressure in those sections, while the pressure on the long rolls of film would be weaker in other sections. Similarly, when locally lower sections overlapped, the pressure on the long rolls of film would be weaker in those sections. Consequently, the long rolls of film could not be supported by each other under uniform pressure over a wide area, which could reduce the ability to suppress blocking and wrinkle formation.

[0013] This invention was conceived in view of the above-mentioned problems, and aims to provide a long film and a method for manufacturing the same that have excellent ability to suppress blocking and wrinkle formation when wound into a roll. [Means for solving the problem]

[0014] The inventors, through diligent research to solve the aforementioned problems, discovered that localized differences in the height of protrusions occur because the protrusions become higher or lower at the starting or ending points of their formation. The inventors then discovered that by dispersing the positions of both the starting and ending points in the film width direction, it is possible to suppress the overlapping of parts with locally differing heights, allowing long films to support each other over a wide area, thus solving the aforementioned problems. Based on these findings, the inventors completed the present invention. In other words, the present invention includes the following:

[0015] [1] A long film having a plurality of knurled portions on at least one surface, each containing a continuous linear protrusion when viewed in the thickness direction, The knurled portions are formed in a line along the longitudinal direction of the film, A long film in which the position of at least one of the highest point and lowest point of each of the knurled portions is dispersed in the film width direction. [2] The long film according to [1], wherein the knurled portion includes a recess and protrusions provided on both sides of the recess. [3] The long film according to [1], wherein the long film includes a base film layer and the protrusions attached to the surface of the base film layer. [4] The process of preparing the film before processing, The process includes forming a plurality of knurled portions, each containing a continuous linear protrusion when viewed from the thickness direction, on at least one surface of the pre-processed film, arranged in the longitudinal direction of the film. The process of forming the knurled portion includes, in this order, forming the protrusion at the starting point, forming the protrusion in the intermediate portion between the starting point and the ending point, and forming the protrusion at the ending point. A method for manufacturing a long film, wherein the positions of both the starting point and the ending point are dispersed in the film width direction. [5] The method for manufacturing a long film according to [4], wherein in the step of forming the knurled portion, the knurled portion is formed by laser light. [6] The method for manufacturing a long film according to [4], wherein in the step of forming the knurled portion, the knurled portion is formed by inkjet printing. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a long film that has excellent ability to suppress blocking and wrinkle formation when wound into a roll, and a method for manufacturing the same. [Brief explanation of the drawing]

[0017] [Figure 1]Figure 1 is a schematic plan view showing a long film according to the first embodiment of the present invention, as viewed from the thickness direction of the long film. [Figure 2] Figure 2 is a schematic plan view showing the planar shape of one of the knurled portions of a long film according to the first embodiment of the present invention, as viewed from the thickness direction of the long film. [Figure 3] Figure 3 is a schematic cross-sectional view showing a cross-section of a linear protrusion included in the knurled portion of a long film according to the first embodiment of the present invention, cut by a plane perpendicular to the direction of extension of the linear protrusion. [Figure 4] Figure 4 is a graph showing the energy of the laser light used to form a linear protrusion in one example. [Figure 5] Figure 5 is a schematic plan view showing the movement of the irradiation point P of the laser beam used to form the linear protrusion. [Figure 6] Figure 6 is a schematic plan view showing the vicinity of the end in the film width direction of a long film according to the first embodiment of the present invention, as viewed from the thickness direction of the long film. [Figure 7] Figure 7 is a schematic, magnified plan view of the area around the knurled portion of the film surface before processing. [Figure 8] Figure 8 is a schematic, magnified plan view of the area surrounding the knurled portion of the film surface before processing. [Figure 9] Figure 9 is a schematic, magnified plan view of the area surrounding the knurled portion of the film surface before processing. [Figure 10] Figure 10 is a schematic plan view showing the planar shape of one of the knurled sections according to a modified example of the first embodiment, as viewed from the thickness direction. [Figure 11] Figure 11 is a schematic plan view showing the planar shape of one of the knurled sections according to a modified example of the first embodiment, as viewed from the thickness direction. [Figure 12] Figure 12 is a schematic plan view showing the vicinity of the end in the film width direction of a long film according to a modified example of the first embodiment, as seen from the thickness direction of the long film. [Figure 13] Figure 13 is a schematic plan view showing the vicinity of the end in the film width direction of a long film according to a modified example of the first embodiment, as seen from the thickness direction of the long film. [Figure 14] Figure 14 is a schematic plan view showing the vicinity of the end in the film width direction of a long film according to a modified example of the first embodiment, as seen from the thickness direction of the long film. [Figure 15] Figure 15 is a schematic plan view showing a long film according to the second embodiment of the present invention, as viewed from the thickness direction of the long film. [Figure 16] Figure 16 is a schematic plan view showing the planar shape of one of the knurled portions of a long film according to the second embodiment of the present invention, as viewed from the thickness direction of the long film. [Figure 17] Figure 17 is a schematic cross-sectional view showing a cross-section of a linear protrusion included in the knurled portion of a long film according to the second embodiment of the present invention, cut by a plane perpendicular to the direction of extension of the linear protrusion. [Modes for carrying out the invention]

[0018] The present invention will be described in detail below with reference to embodiments and examples, but the present invention is not limited to the embodiments and examples shown below and may be implemented with modifications as appropriate without departing from the scope of the claims and their equivalents.

[0019] In the following description, "long film" refers to a film having a length of five times or more its width, preferably 10 times or more its width, and specifically a film long enough to be wound into a roll for storage or transport. There is no particular upper limit to the length of a long film; for example, it may be 100,000 times or less its width.

[0020] In the following description, unless otherwise specified, the planar shape of an element of the film refers to the shape of that element as viewed from the thickness direction of the film.

[0021] In the following explanation, "thickness direction" refers to the thickness direction of the film unless otherwise specified.

[0022] The following explanation may describe the dispersion of multiple points in the film width direction. For example, if we consider one edge of a long film in the film width direction as the reference point, and the distance from each of the multiple points to the edge is uniform for all points, then these points are usually not dispersed in the film width direction. On the other hand, if the distance from each of the multiple points to the edge is not uniform for all points, and there are two or more variations, then these points are usually dispersed in the film width direction.

[0023] In the following explanation, unless otherwise specified, "(meth)acrylic" is a term that encompasses "acrylic," "methacrylic," and combinations thereof, and "(meth)acrylate" is a term that encompasses "acrylate," "methacrylate," and combinations thereof.

[0024] [1. Long film according to the first embodiment] Figure 1 is a schematic plan view showing a long film 10 according to the first embodiment of the present invention, as viewed from the thickness direction of the long film 10. As shown in Figure 1, the long film 10 according to the first embodiment of the present invention is a long film having a plurality of knurled portions 100 on at least one surface 10U. These plurality of knurled portions 100 are formed in the longitudinal direction MD of the long film 10. The knurled portions 100 are usually provided at at least one end of the film width direction TD of the long film 10, preferably at both ends.

[0025] Each knurled portion 100 includes a convex portion 110 having a continuous linear shape when viewed from the thickness direction. Hereinafter, this linear convex portion 110 may be referred to as the "linear convex portion" 110. The planar shapes of each knurled portion 100 when viewed from the film thickness direction may be the same or different. Therefore, the planar shapes of the linear convex portions 110 when viewed from the film thickness direction may be the same or different. In this embodiment, an example is shown in which the planar shapes of both the knurled portion 100 and the linear convex portion 110 are the same.

[0026] Figure 2 is a schematic plan view showing the planar shape of one of the knurled portions 100 of the long film 10 according to the first embodiment of the present invention, as viewed from the thickness direction of the long film 10. As shown in Figure 2, the knurled portion 100 includes a continuous linear protrusion 110. In each knurled portion 100, at least a portion of the linear protrusion 110 extends non-parallel to the longitudinal direction MD of the film. Therefore, the linear protrusion 110 is not formed in only one place in the film width direction TD, but is formed over a specific range. The width L of each knurled portion 100 corresponds to the width of the range in which the linear protrusion 110 is formed. TD It could be equivalent to this.

[0027] In this embodiment, an example in which the knurled portion 100 is formed by irradiation with laser light will be described. Specifically, in the example shown in this embodiment, the linear protrusions 110 are formed as traces left by the movement of the laser light irradiation point (corresponding to the drawing point), and are usually formed as continuous lines drawn in a single stroke. The knurled portion 100 has a specific planar shape drawn by such linear protrusions 110.

[0028] Figure 3 is a schematic cross-sectional view showing a cross-section of a linear protrusion 110 included in the knurled portion 100 of a long film 10 according to the first embodiment of the present invention, cut by a plane perpendicular to the extending direction of the linear protrusion 110. As shown in Figure 3, the knurled portion 100 according to this embodiment includes a recess 120 and linear protrusions 110 provided on both sides of the recess 120. Typically, the recess 120 corresponds to the portion where the resin has been removed by thermal melting or ablation due to laser irradiation, and the linear protrusions 110 correspond to the portion where the resin has been heated and fluidized by the laser irradiation and has risen up. Since the linear protrusions 110 protrude beyond the surface 10U of the surrounding long film 10, the effective thickness of the long film 10 is increased in the knurled portion 100 including these linear protrusions 110.

[0029] In the direction of extension of the linear protrusion 110, the height H of the linear protrusion 110 is not constant. Therefore, each linear protrusion 110 contained within a knurled section 100 contains one or both of its highest and lowest points. The highest point of a linear protrusion 110 contained within a certain knurled section 100 represents the point where the height H of the linear protrusion 110 is highest. Conversely, the lowest point of a linear protrusion 110 contained within a certain knurled section 100 represents the point where the height H of the linear protrusion 110 is lowest. Therefore, the height H of a linear protrusion 110 contained within a certain knurled section 100 can be highest at its highest point and lowest at its lowest point in the direction of extension of the linear protrusion 110.

[0030] The highest and lowest points, or both, may be formed at the starting or ending point of the formation of the linear protrusion 110 by laser light. The mechanism by which the highest or lowest point of the linear protrusion 110 is formed by laser light irradiation will be described below. However, the mechanism described below is just one example, and the mechanism by which the highest and lowest points are formed is not limited to this example.

[0031] First, we will explain an example in which the highest point of the linear protrusion 110 is formed at the starting point of the formation of the linear protrusion 110 by laser light. Figure 4 is a graph showing the energy of the laser light used to form the linear protrusion 110 in one example. In the graph shown in Figure 4, the horizontal axis represents time, and the vertical axis represents the energy of the laser light. Normally, a laser oscillator, which is a source of laser light, increases the energy of the laser light within the laser oscillator and emits the laser light by opening the shutter. At this time, immediately after the shutter is opened, as shown in Figure 4, the light in a high-energy state within the laser oscillator can be temporarily extracted. Therefore, at the starting point of the formation of the linear protrusion 110, the stabilized energy E irradiated from that starting point onward is S It is possible that a laser beam with an energy E0 higher than that may be irradiated. When such a high-energy E0 laser beam is irradiated, a large amount of resin is heated and fluidized at the starting point where the laser beam is irradiated, and a high linear protrusion 110 may be formed.

[0032] Furthermore, generally, to move the laser beam irradiation point, the angle of the reflective mirror is adjusted by moving the reflective mirror using a drive device such as a galvanometer motor. When moving the laser beam irradiation point from the starting point, the reflective mirror, which was in a stationary state, is moved. When the reflective mirror starts moving, it takes time to accelerate the reflective mirror against the inertial force. For the amount of time required, the laser beam hits the starting point for a long time. Therefore, a large amount of resin is heated and fluidized at the starting point, and this can also form a high linear protrusion 110.

[0033] Secondly, we will explain an example in which the lowest point of the linear protrusion 110 is formed at the starting point of the formation of the linear protrusion 110 by laser light. Figure 5 is a schematic plan view showing how the irradiation point P of the laser light irradiated to form the linear protrusion 110 moves. When the linear protrusion 110 is formed, as shown in Figure 5, the laser light first strikes the starting point 110S. Then, the laser light is irradiated while the irradiation point P moves as indicated by arrow A1, and the linear protrusion 110 (not shown in Figure 5) is formed as the trace left by the movement of the irradiation point P. In this case, the laser light strikes points where the linear protrusion 110 is formed after the starting point 110S (specifically, points in the intermediate section 110M, which will be described later) for a relatively longer period of time. Specifically, a relatively long time passes from when the irradiation point P reaches that point until when the irradiation point P leaves that point. However, it is possible that the laser light strikes the starting point 110S for a relatively short period of time. In particular, the leftmost part V in the diagram at the starting point 110S S In this case, the laser light stops hitting the area as soon as the irradiation point P begins to move, so the irradiation time of the laser light is particularly short. Because the irradiation time of the laser light is short in this way, less resin is fluidized by heating with the laser light, so low linear protrusions 110 can be formed. Also, depending on the laser light source, the laser light energy may be high in the center of the irradiation point P and low at the outer edge of the irradiation point P. When such a light source is used, the portion V corresponding to the outer edge of the irradiation point P... S Because only very low energy is supplied to this part by the laser light, this part V S The height H of the linear protrusion 110 tends to be particularly low.

[0034] Thirdly, we will describe an example in which the highest point of the linear protrusion 110 is formed at the endpoint 110E of the formation of the linear protrusion 110 by the laser light. As mentioned above, generally, in order to move the irradiation point of the laser light, the angle of the reflective mirror is adjusted by moving the reflective mirror with a drive device. When stopping the irradiation point of the laser light at the endpoint 110E of the formation of the linear protrusion 110, the reflective mirror that was in the operating state is stopped. When the operation of the reflective mirror is stopped, it takes time to stop the reflective mirror against the inertial force. For the amount of time required, the laser light shines on the endpoint 110E of the formation of the linear protrusion 110 for a long time. Therefore, a large amount of resin is heated and fluidized at the endpoint 110E, and as a result, a high linear protrusion 110 can be formed.

[0035] Fourth, we will describe an example in which the lowest point of the linear protrusion 110 is formed at the endpoint 110E of the formation of the linear protrusion 110 by laser light. As shown in Figure 5, when the laser light is irradiated while moving the irradiation point P as indicated by arrow A1 to form the linear protrusion 110 (not shown in Figure 5), as described above, the laser light hits the points where the linear protrusion 110 is formed before the endpoint 110E of the linear protrusion 110 (specifically, the points in the intermediate part 110M described later) for a relatively long time. However, it is possible that the laser light hits the endpoint 110E for a relatively short time. In particular, the rightmost part V in the figure of the endpoint 110E E Since the laser light only hits the area for a short time just before the irradiation point P stops moving, the irradiation time of the laser light is particularly short. Because the irradiation time of the laser light is so short, less resin is fluidized by heating with the laser light, so a low linear protrusion 110 can be formed. Furthermore, if a light source is used that emits laser light with high energy at the center of the irradiation point P and low energy at the outer edge of the irradiation point P, the portion V corresponding to the outer edge of the irradiation point P will be affected. E Because only very low energy is supplied to this part by the laser light, this part V E The height H of the linear protrusion 110 tends to be particularly low.

[0036] Furthermore, depending on the conditions during laser irradiation, the output of the laser light may decrease over time after the shutter of the laser oscillator is opened. For example, the aforementioned decrease in output may occur due to factors such as changes in the excitation state and temperature of the gas inside the laser oscillator caused by opening the shutter. When such a decrease in output occurs, less resin is fluidized by heating with laser light, so low linear protrusions 110 may be formed.

[0037] As described above, the highest or lowest point of the linear protrusion 110 may be formed at the starting and ending points of the formation of the linear protrusion 110 by the laser light. Whether the highest and lowest points of the linear protrusion 110 are formed at the starting point or the ending point may depend on the formation conditions of the linear protrusion 110. Also, for example, if the starting point and the ending point are at the same location, the linear protrusion 110 may have only one of the highest and lowest points.

[0038] In all of these cases, conventionally, the start and end points were not dispersed in the film width direction TD, but were typically set at fixed positions. Therefore, conventionally, the highest and lowest points of the linear protrusions were also not dispersed in the film width direction TD, but were typically at fixed positions. When points such as the start, end, highest, and lowest points are not dispersed in the film width direction, the distance from each of these points to a reference line extending in a direction perpendicular to both the film width direction TD and the film thickness direction (in this embodiment, the film longitudinal direction MD) was usually uniform for all points. Here, the aforementioned reference line does not need to be actually drawn and can be a virtual straight line, but for example, one edge of the film width direction TD of a long film can be used. To explain using this example, conventionally, the distance from each of the multiple points that are not dispersed in the film width direction TD as described above to the edge of the long film was usually uniform for all points. Therefore, when long films are wound together, the highest points of the wound films overlap, which can amplify the local height of the highest point. Also, when long films are wound together, the lowest points of the wound films overlap, which can amplify the local lowness of the lowest point. In either of these cases, in the film width direction (TD), the wound films can only support each other at a portion of the knurled section, which can result in a lack of ability to suppress blocking and wrinkle formation.

[0039] In contrast, in this embodiment, the position of at least one of the highest and lowest points of each linear protrusion 110 of the knurled portion 100 is dispersed in the film width direction TD. As described above, the highest and lowest points of the linear protrusion 110 can be formed at the starting or ending point of the formation of the linear protrusion 110. Therefore, a long film 10 having a knurled portion 100 including linear protrusions 110 whose highest and lowest points are dispersed can be obtained by dispersing the positions of both the starting and ending points in the film width direction TD.

[0040] Hereinafter, an example in which the positions of both the starting point and the ending point are dispersed in the film width direction TD, and the highest points 110H of the linear convex portions 110 corresponding to both the starting point and the ending point are dispersed in the film width direction TD will be described. In this example, since points such as the starting point, the ending point, and the highest point 110H are dispersed in the film width direction TD, the distances from each of these points to the reference line are not uniform at all points and there can be two or more variations. Therefore, for example, when explaining the dispersion of the highest point 110H by adopting one edge in the film width direction TD of the long film 10 as the reference line, the distances from each of the plurality of highest points 110H to the edge of the long film 10 are not uniform for all the highest points 110H and there can be two or more variations. This mode of dispersion can be the same not only for the highest point 110H but also for the lowest point, the starting point, and the ending point.

[0041] FIG. 6 is a plan view schematically showing a state of the vicinity of an end portion in the film width direction TD of the long film 10 according to the first embodiment of the present invention as viewed from the thickness direction of the long film 10. As shown in FIG. 6, a group of narl portions 100 formed side by side in the film longitudinal direction MD on the long film 10 according to the example shown in this embodiment have the highest points 110H of the linear convex portions 110 at different positions in the film width direction TD. Therefore, the highest points 110H are provided dispersedly at a plurality (here, four positions) of positions in the film width direction TD.

[0042] When the highest points 110H are provided dispersedly in the film width direction TD in this way, the highest points 110H of the long film 10 that are wound and overlapped in the roll do not concentrate and overlap at one position in the film width direction TD, but overlap dispersedly at a plurality of different positions. Therefore, the substantial thickness uniformity of the portion (in this embodiment, the end portion of the long film 10) where the narl portions 100 are provided is improved as a whole of the roll. Therefore, the long films 10 can support each other with equal pressure over a wide area portion corresponding to the entire width L TD of the narl portion 100, so that the ability to suppress the occurrence of blocking and wrinkles can be improved.

[0043] The distance D between the highest points 110H, which are distributed in the film width direction TD. 110H The width L of the knurled portion 100 includes the linear protrusion 110 having its highest point 110H. TD In contrast, 0.01 × L TD Above, 0.5 × L TD The following is preferable: The distance D between the highest points 110H 110H When the range is as described above, the uniformity of the substantial thickness of the portion where the knurled portion 100 is provided can be effectively increased, thereby effectively enhancing the ability to suppress blocking and wrinkle formation. Also, the interval D 110H While they may differ, uniformity is preferable from the viewpoint of particularly effectively suppressing blocking and wrinkle formation.

[0044] From the viewpoint of enhancing the ability to suppress blocking and wrinkle formation, as shown in Figure 2, it is preferable that the linear protrusions 110 included in the knurled portion 100 have a planar shape with corners 111. Furthermore, the number of corners 111 in the planar shape of a linear protrusion 110 of a single knurled portion 100 may be 1, but 2 or more is preferable. In addition, the angles θ of these corners are preferably 80° or more, more preferably 85° or more, particularly preferably 88° or more, and also preferably in the range of 100° or less, more preferably 95° or less, particularly preferably 92° or less. In this embodiment, a linear protrusion 110 having a zigzag planar shape including a plurality of corners 111 and a plurality of straight sections 112 connecting these corners 111 will be shown and explained as an example.

[0045] Furthermore, the planar shape of the linear protrusion 110 may be endless. More specifically, the linear protrusion 110 may have an endless shape because it is formed in a continuous ring shape when viewed from the thickness direction. When forming such an endless linear protrusion 110 with laser light, the starting point and ending point of the formation of the linear protrusion 110 can be set to the same point, as shown in the example of this embodiment.

[0046] The width L of each knurled section 100 in the film width direction TD of the long film 10.TD And the length L of each knurled section 100 in the longitudinal direction MD of the long film 10. MD Ratio L TD / L MD It is preferable that it falls within a predetermined range. Specifically, the ratio L TD / L MD The ratio L is preferably 2 or more, more preferably 2.5 or more, and particularly preferably 3 or more. TD / L MD However, if it falls within the range mentioned above, the knurled portion 100 can be smoothly formed while suppressing the deformation of the planar shape. The ratio L mentioned above TD / L MD There is no particular upper limit, but it is preferably 15 or less, more preferably 13 or less, and especially preferably 10 or less. Width L of the knurled section 100 TD This represents the distance of the area where the linear protrusions 110 are formed in the film width direction TD. Also, the length L of the knurled portion 100. MD This represents the distance of the area in which the linear protrusions 110 are formed in the longitudinal direction MD of the film.

[0047] Width L of the knurled section 100 TD and length L MD These are, respectively, the ratio L mentioned above. TD / L M It is preferable to set it appropriately so that it falls within the range described above. Specifically, the width L of each knurled section 100 in the film width direction TD. TD Preferably, it is 3 mm or more, more preferably 5 mm or more, particularly preferably 7 mm or more, preferably 20 mm or less, more preferably 17 mm or less, particularly preferably 15 mm or less.

[0048] Furthermore, the length L of each knurled portion 100 in the longitudinal direction MD of the film. MD The thickness is preferably 0.1 mm or more, more preferably 0.5 mm or more, particularly preferably 1 mm or more, preferably 20 mm or less, more preferably 15 mm or less, and particularly preferably 10 mm or less.

[0049] As shown in Figure 1, the knurled portions 100 are usually arranged in the longitudinal direction MD of the long film 10 at a specific pitch. In this case, the pitch of the knurled portions 100 is preferably 0.5 mm or more, more preferably 1 mm or more, particularly preferably 1.5 mm or more, preferably 10 mm or less, more preferably 7 mm or less, and particularly preferably 5 mm or less. The pitch of the knurled portions 100 may be constant or varied. Typically, the pitch of the knurled portions 100 matches the pitch of the linear protrusions 110 included in the knurled portions 100.

[0050] As shown in Figure 3, the linear protrusion 110 protrudes from the surface 10U of the surrounding long film 10 and therefore has a specific height H. Typically, the linear protrusion 110 has one or both of the highest point 110H (see Figure 6) and the lowest point (not shown) at the starting or ending point of its formation. Furthermore, in the case of a linear protrusion 110 having a corner 111 as shown in this embodiment, the corner 111 tends to be higher than the straight section 112. Thus, the height H of a single linear protrusion 110 is not constant in the direction of extension of the linear protrusion 110. Even in this case, in the roll obtained by winding the long film 10 according to this embodiment, the width L of the knurled section 100 TD The long films 10 can support each other with uniform pressure over a wide area corresponding to the entire surface. Therefore, blocking and wrinkle formation can be suppressed.

[0051] The average height of the linear protrusions 110 at the corners 111 is preferably 1 μm or more, more preferably 2 μm or more, particularly preferably 3 μm or more, preferably 25 μm or less, more preferably 20 μm or less, and particularly preferably 15 μm or less. Similarly, the average height of the linear protrusions 110 at the straight sections 112 is preferably 0.5 μm or more, more preferably 1 μm or more, particularly preferably 1.5 μm or more, preferably 25 μm or less, more preferably 20 μm or less, and particularly preferably 15 μm or less. When the linear protrusions 110 have such heights, blocking and wrinkle formation can be effectively suppressed.

[0052] As shown in Figure 3, the knurled portion 100 formed by laser light typically comprises a recess 120 and linear protrusions 110 provided on both sides of the recess 120. Typically, the width of these linear protrusions 110 and recess 120 is narrow, so to the naked eye, the combination of the recess 120 and linear protrusions 110 can be seen as a single line. The width W of the combination of the recess 120 and linear protrusions 110 is preferably 0.1 μm or more, more preferably 0.15 μm or more, particularly preferably 0.2 μm or more, preferably 1 μm or less, more preferably 0.75 μm or less, and particularly preferably 0.5 μm or less. When the width of the combination of the recess 120 and linear protrusions 110 is within the above range, blocking and wrinkle formation can be effectively suppressed.

[0053] There are no particular restrictions on the width and thickness of the long film 10, and a width and thickness can be adopted according to the intended use. The width of the long film 10 is preferably 700 mm or more, more preferably 1000 mm or more, even more preferably 1200 mm or more, preferably 2500 mm or less, more preferably 2200 mm or less, and even more preferably 2000 mm or less. The thickness of the long film 10 is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 20 μm or more, preferably 1000 μm or less, more preferably 300 μm or less, and even more preferably 150 μm or less.

[0054] When the long film 10 is used as an optical film, it is preferable that it has high transparency in the region without the knurled portion 100. Specifically, the total light transmittance of the long film 10 in the aforementioned region is preferably 85% to 100%, more preferably 92% to 100%. The haze of the long film 10 in the aforementioned region is preferably 0% to 5%, more preferably 0% to 3%, and particularly preferably 0% to 2%. Here, the total light transmittance can be measured using a "turbidimeter NDH-2000" manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K7105. The haze can also be measured using a "turbidimeter NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd.

[0055] The long film according to the first embodiment described above is A step of preparing a pre-processed film as a film before the formation of the knurled portion 100; The process involves forming multiple knurled portions 100 on at least one surface of the film before processing, arranged in the longitudinal direction MD of the film; It can be manufactured by a manufacturing method that includes [the specified ingredient]. The manufacturing method is described below.

[0056] In the process of preparing the pre-treatment film, a long film is usually prepared that is the same as the long film except that the knurled portion 100 is not formed. The method of preparing this pre-treatment film is not particularly limited. The pre-treatment film may be purchased from the market, for example. Alternatively, the pre-treatment film may be manufactured using the same materials as the long film 10. The method for manufacturing the pre-treatment film will be described later.

[0057] After preparing the pre-treatment film, knurled portions 100 are formed on the surface of the pre-treatment film. In this embodiment, the knurled portions 100 are formed using laser light. Therefore, the step of forming the knurled portions 100 includes irradiating the pre-treatment film with laser light. When laser light is irradiated onto the surface of the pre-treatment film, localized thermal melting or ablation occurs at the location irradiated with laser light. As a result, convex and concave deformations can be caused in the pre-treatment film at the location irradiated with laser light.

[0058] Figures 7 to 9 are schematic, magnified plan views of the area around the knurled portion 100 on the surface of the film before processing. In Figures 7 and 8, the dashed lines represent the areas where the linear protrusions 110 of the knurled portion 100 are to be formed. As shown in Figures 7 to 9, the process of forming a single knurled portion 100 includes, in this order, forming the linear protrusion 110 at the starting point 110S (Figure 7), forming the linear protrusion 110 in the intermediate section 110M between the starting point 110S and the ending point 110E (see Figure 9) (Figure 8), and forming the linear protrusion 110 at the ending point 110E (Figure 9). Here, "intermediate section 110M" refers to the section connecting the starting point 110S, where the linear protrusion 110 is first formed, and the ending point 110E, where the linear protrusion 110 is last formed. Therefore, this intermediate portion 110M may be a linear portion consisting of a set of points where the linear protrusion 110 is formed, excluding the starting point 110S and the ending point 110E.

[0059] In detail, in the process of forming the knurled portion 100, as shown in Figure 7, laser light is irradiated onto the starting point 110S. That is, the laser light is irradiated so that the irradiation point P of the laser light is formed at the starting point 110S. As a result, convex and concave deformations occur at the starting point 110S where the irradiation point P is formed, and the linear convex portion 110 is formed. After that, as shown by arrow A2, the movement of the irradiation point P is started.

[0060] As the irradiation point P begins to move, it moves in a manner that traces a predetermined planar shape, as indicated by arrow A3 in Figure 8. This causes convex and concave deformations to occur in the path left by the irradiation point P. As a result, a linear convex portion 110 is formed in the intermediate portion 110M as the trajectory of the irradiation point P.

[0061] The irradiation point P passes through the entire intermediate section 110M and then reaches the endpoint 110E, as shown by arrow A4 in Figure 9. This causes convex and concave deformations at the endpoint 110E, forming a linear convex portion 110. In the example shown in this embodiment, the starting point 110S and the endpoint 110E are set to the same location. As described above, linear convex portions 110 are formed at the starting point 110S, the intermediate section 110M, and the endpoint 110E, thus forming a knurled section 100 having a linear convex portion 110 with a specific planar shape. When the irradiation point P reaches the endpoint 110E, the irradiation of the laser light is stopped.

[0062] The formation of the knurled portion 100 is usually carried out while the pre-processed film is continuously transported in the longitudinal direction of the pre-processed film. Therefore, after the formation of one knurled portion 100 is completed, the formation of the next knurled portion 100 is started. Thus, in the manufacturing method of the long film 10, the knurled portions 100 can be formed sequentially in the longitudinal direction MD of the film.

[0063] In this embodiment, when manufacturing multiple knurled portions 100 arranged in the longitudinal direction MD of the film, the positions of both the starting point 110S and the ending point 110E are distributed to multiple different positions in the film width direction TD. As a result, as shown in Figure 6, at least one of the highest point 110H and the lowest point (not shown) of the linear protrusion 110 corresponding to the starting point or ending point can be distributed in the film width direction TD.

[0064] For example, the first starting point 110S i From the first terminus, 110E i The laser beam irradiation point P (not shown in Figure 6) is continuously moved until the first linear protrusion 110 i Forms the first knurled portion 100 i To form; second starting point 110S ii From the second terminus, 110E ii The laser beam irradiation point P is continuously moved until the second linear protrusion 110 ii Forms the second knurled portion 100 iiTo form; the third starting point 110S iii From the third terminus, 110E iii The laser beam irradiation point P is continuously moved until the third linear protrusion 110 iii Forms the third knurled portion 100 iii To form; and the fourth starting point 110S iv From the fourth terminus, 110E iv The laser beam irradiation point P is continuously moved until the fourth linear protrusion 110 iv This forms the fourth knurled portion 100 iv Assume that the following steps are performed in this order: forming the first starting point 110S i , second starting point 110S ii , third starting point 110S iii , and the fourth starting point 110S iv This is set at different positions in the film width direction TD. Furthermore, the first endpoint 110E i , the second terminus 110E ii , the third terminus 110E iii , and the fourth terminus 110E iv This is set at different positions in the film width direction TD. This results in the first to fourth knurled sections 100 being aligned in the film longitudinal direction MD. i ~100 iv The film width direction TD may have a highest point 110H or a lowest point (not shown) at different positions. And these first to fourth knurled parts 100 i ~100 iv By repeatedly forming the film, a long film 10 can be manufactured that has a maximum point 110H or a minimum point (not shown) dispersed in the film width direction TD throughout the film.

[0065] In this case, there is no restriction on the order in which the knurled sections 100, which have their highest point 110H or lowest point (not shown) at different positions, are arranged. Therefore, the knurled sections 100 may be arranged in a regular pattern. For example, the first to fourth knurled sections 100 i ~100 iv These may be repeated in this order. Therefore, the starting points 110S of the first to fourth i ~110Siv The starting point 110S, and the first to fourth ending points 110E. i ~110E iv The positions of the endpoints 110E, etc., may be set with regularity in the film width direction TD. Also, the knurled sections 100 may be arranged randomly without any regularity. Therefore, the first to fourth starting points 110S i ~110S iv The starting point 110S, and the first to fourth ending points 110E. i ~110E iv The positions of the endpoints 110E, etc., may be set randomly in the film width direction TD.

[0066] As described above, by distributing the positions of both the starting point 110S and the ending point 110E to multiple different positions in the film width direction TD to form the knurled portion 100, a long film 10 can be obtained in which multiple knurled portions 100 are formed, including linear protrusions 110 having the highest point 110H or lowest point (not shown) distributed in the film width direction TD as described above.

[0067] The formation of the knurled portion 100 using laser light does not require mechanical force. Therefore, residual stress is less likely to remain in the knurled portion 100. As a result, the occurrence of breakage originating from the knurled portion 100 in the long film 10 can be suppressed. Furthermore, even when using a thin pre-treated film, it is easier to suppress film breakage during the formation of the knurled portion 100. In addition, the generation of foreign matter due to the formation of the knurled portion 100 can be suppressed.

[0068] The movement speed of the laser beam irradiation point P can be appropriately set within a range that allows for the formation of the desired knurled portion 100. Specifically, the movement speed is preferably 500 mm / s or more, more preferably 1000 mm / s or more, particularly preferably 1500 mm / s or more, preferably 10000 mm / s or less, more preferably 9000 mm / s or less, and particularly preferably 8000 mm / s or less. When the movement speed of the laser beam irradiation point P is above the lower limit of the above range, the time required for drawing can be shortened, and the knurled portion 100 can be formed at high speed. Furthermore, when the movement speed of the laser beam irradiation point P is below the upper limit of the above range, the occurrence of overshoot due to the inertia of the movable parts (mirrors, etc.) included in the laser optical system can be suppressed, thereby suppressing deformation from the desired shape.

[0069] Examples of laser devices used for irradiating laser light include ArF excimer lasers, KrF excimer lasers, XeCl excimer lasers, YAG lasers (especially third or fourth harmonic), YLF or YVO4 solid-state lasers (especially third or fourth harmonic), Ti:S lasers, semiconductor lasers, fiber lasers, and carbon dioxide lasers. Among these laser devices, carbon dioxide lasers are preferred because they are relatively inexpensive and can efficiently provide output suitable for film processing.

[0070] The laser light output is preferably 1W or more, more preferably 5W or more, even more preferably 15W or more, preferably 120W or less, more preferably 100W or less, even more preferably 80W or less, and even more preferably 70W or less. When the laser light output is above the lower limit of the above range, insufficient laser light irradiation can be suppressed, and the knurled portion 100 can be stably formed. Also, when the laser light output is below the upper limit of the above range, the occurrence of through holes in the film can be suppressed.

[0071] [2. Examples of modifications to the first embodiment] The above describes a first embodiment of a long film 10 equipped with knurled sections 100 formed using laser light. However, the first embodiment may be further modified.

[0072] For example, instead of the highest point 110H of the linear protrusion 110, the lowest point of the linear protrusion 110 may be dispersed in the film width direction TD. Alternatively, for example, both the highest point 110H and the lowest point may be dispersed in the film width direction TD. The manner in which the lowest point is dispersed may be the same as that of the highest point 110H. Furthermore, the method for forming the dispersed lowest point may be the same as the method for forming the highest point 110H.

[0073] In the first embodiment described above, an example was shown in which the highest point 110H of the linear protrusion 110 was distributed to four locations in the film width direction TD. However, the number of locations where the highest point 110H is distributed is not limited to four. Therefore, the number of locations where the highest point 110H is distributed may be two, three, or five or more. Among these, ten or more locations are preferred. Also, similar to the highest point 110H, when the lowest point of the linear protrusion is distributed in the film width direction TD, the number of locations where the lowest point is distributed may be two, three, four, or five or more, with ten or more being preferred. Furthermore, the number of locations where the start and end points of the formation of the linear protrusion 110 are distributed may also be two, three, four, or five or more, similar to the highest point 110H and the lowest point, with ten or more being preferred.

[0074] In the first embodiment described above, an example was shown in which the starting point 110S and ending point 110E for the formation of a single linear protrusion 110 were set at the same position. However, these starting point 110S and ending point 110E may be set at different positions.

[0075] Figure 10 is a schematic plan view showing the planar shape of one of the knurled portions 200 according to a modified example of the first embodiment, viewed from the thickness direction. As shown in Figure 10, for example, a knurled portion 200 in which the planar shape of the linear protrusion 210 is not an endless shape can be formed by a manufacturing method that includes irradiating a laser beam from a starting point 210S to an ending point 210E located at a different position from the starting point 210S, such that the irradiation point P (not shown in Figure 10) moves as shown by arrow A5.

[0076] Figure 11 is a schematic plan view showing the planar shape of one of the knurled sections 300 according to a modified example of the first embodiment, viewed from the thickness direction. As shown in Figure 11, for example, according to a manufacturing method that includes irradiating a part 313 of the linear protrusion 310 with laser light such that the irradiation point P (not shown in Figure 10) passes through it multiple times as shown by arrow A6, the knurled section 300 can be formed by setting the starting point 310S and the ending point 310E at different positions. That is, the irradiation point P, which starts from the starting point 310S, moves to draw the planar shape of the linear protrusion 310 and returns to the starting point 310S, and then passes through part 313 of the linear protrusion 310 to reach the ending point 310E, thereby forming the knurled section 300.

[0077] In the embodiment described above, only one knurled portion 100 was formed in the film width direction TD, but multiple knurled portions may be formed side by side in the film width direction TD. Figures 12 and 13 are schematic plan views, respectively, showing the vicinity of the ends of the long films 20 and 30 in the film width direction TD as seen from the thickness direction of the long films 20 and 30, according to a modified example of the first embodiment. For example, as shown in Figures 12 and 13, multiple knurled portions 400 and 500 may be formed side by side not only in the film longitudinal direction MD, but also in the film width direction TD.

[0078] In the long film 20 shown in Figure 12, three knurled portions 400, each containing a linear protrusion 410 having the same circular planar shape, are formed in a row along the film width direction TD. In this case, the knurled portions 400 may be formed in three rows along the film longitudinal direction MD. Furthermore, in the long film 30 shown in Figure 13, four knurled portions 500, each containing a linear protrusion 510 having the same rectangular planar shape, are formed in a row along the film width direction TD. In this case, the knurled portions 500 can be formed in four rows along the film longitudinal direction MD. In either case, by dispersing the positions of both the starting and ending points for forming the linear protrusions 410 and 510 in the groups of knurled portions 400 and 500 formed side by side in the longitudinal direction MD of the film in the film width direction TD, the positions of at least one of the highest and lowest points of the linear protrusions 410 and 510 of each group of knurled portions 400 and 500 can be dispersed in the film width direction TD.

[0079] Specifically, in the long film 20 shown in Figure 12, a laser beam is irradiated from the starting point 410S to the ending point 410E, as indicated by arrow A7, so that the trajectory of the irradiation point P (not shown in Figure 12) traces a circle, thereby forming a linear protrusion 410. The linear protrusions 410 of the three knurled sections 400 aligned in the film width direction TD all have the same starting point 410S and ending point 410E in their circular planar shape. Even in this case, in the group of knurled sections 400 aligned in the film longitudinal direction MD, by dispersing the positions of both the starting point 410S and the ending point 410E in the film width direction TD, the position of at least one of the highest point 410H and lowest point (not shown) of the linear protrusion 410 of the knurled section 400 in that group can be dispersed in the film width direction TD.

[0080] Furthermore, in the long film 30 shown in Figure 13, the laser beam is irradiated from the starting point 510S to the ending point 510E, as indicated by arrow A8, so that the trajectory of the irradiation point P (not shown in Figure 13) traces a rectangle, thereby forming the linear protrusions 510. The linear protrusions 510 of the four knurled sections 500 arranged in the film width direction TD each have their starting point 510S and ending point 510E set at different positions in their rectangular planar shape. Moreover, in the group of knurled sections 500 arranged in the film longitudinal direction MD, the positions of both the starting point 510S and the ending point 510E are dispersed in the film width direction TD. In this case as well, the position of at least one of the highest point 510H and the lowest point (not shown) of the linear protrusions 510 of the knurled section 500 in that group can be dispersed in the film width direction TD.

[0081] As shown in Figures 12 and 13, when multiple knurled portions 400 and 500 are formed in the film width direction TD, the number of knurled portions 400 and 500 arranged in the film width direction TD is not limited to the above example. Furthermore, the planar shapes of the linear protrusions 410 and 510 included in each of the knurled portions 400 and 500 arranged in the film width direction TD may be the same or different.

[0082] In the embodiment described above, an example was shown in which the planar shape of the linear protrusion 110 included in the knurled portion 100 is an endless shape, but the planar shape of the linear protrusion does not have to be endless. Figure 14 is a schematic plan view of the vicinity of the end in the film width direction TD of a long film 40 according to a modified example of the first embodiment, as seen from the thickness direction of the long film 40. For example, as shown in Figure 14, the long film 40 may have a knurled portion 600 that includes a linear protrusion 610 having a planar shape other than an endless shape.

[0083] A knurled portion 600 including a linear protrusion 610 having a planar shape other than an endless shape can have at least one of the highest point 610H and lowest point (not shown) of the linear protrusion 610 of the knurled portion 600 distributed in the film width direction TD by distributing the positions of both the starting and ending points to multiple different positions in the film width direction TD. For example, in the example shown in Figure 14, a certain knurled portion 600 i Linear protrusion 610 i The starting point 610S is set on the left side of the diagram. i The endpoint 610E is set to the right in the diagram. i The laser beam is irradiated so that the irradiation point P (not shown in Figure 14) moves as shown by arrow A9, and then the knurled portion 600 is formed. ii Linear protrusion 610 ii The starting point 610S is set on the right side of the diagram. ii The endpoint 610E is set to the left in the diagram. ii The laser beam is irradiated so that the irradiation point P moves as shown by arrow A10, and then it is formed. iii Linear protrusion 610 iii The first starting point 610S is set at one end.iii to the first end point 610E iii until, as shown by arrow A11, the laser light is irradiated so that the irradiation point P moves, and at the first end point 610E iii and a second start point 610S set at the same position iv from to the second end point 610E iv until, as shown by arrow A12, the laser light is irradiated so that the irradiation point P moves, and by doing so, it is formed. These first to third narl parts 600 i ~600 iii By repeating the formation of, the linear convex parts 610 i ~600 iii of these narl parts 600 i ~610 iii of at least one of the highest point and the lowest point can be dispersed in the film width direction TD.

[0084] [3. Long film according to the second embodiment] In the above-described first embodiment, a long film in which a narl part is formed by irradiation with laser light has been described, but the method of forming the narl part is not limited to laser light. For example, the narl part may be formed by inkjet printing. An example thereof will be described below.

[0085] FIG. 15 is a plan view schematically showing a long film 50 according to the second embodiment of the present invention as viewed from the thickness direction of the long film 50. FIG. 16 is a plan view schematically showing the planar shape of one of the narl parts 700 included in the long film 50 according to the second embodiment of the present invention as viewed from the thickness direction of the long film 50.

[0086] As shown in Figures 15 and 16, the long film 50 according to the second embodiment of the present invention is provided in the same way as the long film 10 according to the first embodiment, except that the knurled portions 700 are formed by inkjet printing. Therefore, the long film 50 according to this embodiment is a long film having a plurality of knurled portions 700 on at least one surface 50U. These plurality of knurled portions 700 are arranged in the longitudinal direction MD of the long film 50. In addition, each knurled portion 700 includes a linear protrusion 710 having a continuous linear shape when viewed from the thickness direction.

[0087] In this embodiment, the knurled portion 700 is formed by inkjet printing. Specifically, in the example shown in this embodiment, the linear protrusions 710 are formed as lines drawn with ink printed by inkjet printing. The knurled portion 700 has a specific planar shape drawn by such linear protrusions 710.

[0088] Figure 17 is a schematic cross-sectional view showing a cross-section of a linear protrusion 710 included in the knurled portion 700 of a long film 50 according to the second embodiment of the present invention, cut by a plane perpendicular to the extending direction of the linear protrusion 710. As shown in Figure 17, the long film 50 according to this embodiment includes a base film layer 51 corresponding to the pre-processed film before the formation of the knurled portion 700, and linear protrusions 710 attached to the surface 51U of the base film layer 51. The linear protrusions 710 are formed by ink attached to the surface 51U by inkjet printing. Here, ink includes not only liquid ink but also ink that has hardened after printing. The linear protrusions 710 protrude from the surrounding surface 50U of the long film 50 by the amount of ink that forms the linear protrusions 710. Therefore, in the knurled portion 700 including these linear protrusions 710, the effective thickness of the long film 50 is increased.

[0089] In the direction of extension of the linear protrusion 710, the height H of the linear protrusion 710 is not constant. Therefore, the linear protrusion 710 included in each knurled portion 700 includes one or both of the highest and lowest points. One or both of the highest and lowest points may be formed at the start or end point of the formation of the linear protrusion 710 by inkjet printing. The mechanism by which the highest or lowest point of the linear protrusion 710 is formed by inkjet printing will be described below. However, the mechanism described below is just one example, and the mechanism by which the highest and lowest points are formed is not limited to this example.

[0090] In inkjet printing, liquid ink is ejected from a nozzle, and the ejected ink adheres to the film surface, achieving the formation of linear protrusions 710. However, due to the surface tension of the liquid ink before ejection, the amount of ink ejected from the nozzle may increase or decrease at the start and end of printing. For example, if the liquid surface of the ink protrudes above the nozzle opening due to surface tension, the amount of ink ejected may increase. Conversely, if the liquid surface of the ink is recessed below the nozzle opening due to surface tension, the amount of ink ejected may decrease. Such increases and decreases in ink volume are likely to occur at the start and stop of ink ejection from the nozzle. Therefore, the highest and lowest points of the linear protrusions 710 may be formed at the start or end point of the formation of the linear protrusions 710 by inkjet printing. Whether the highest and lowest points of the linear protrusions 710 are formed at the start or end point may depend on printing conditions such as the inkjet printer's drive unit, nozzle shape, and ejection speed.

[0091] In the aforementioned inkjet printing, linear protrusions are typically formed by moving the drawing point by moving the nozzle relative to the film surface, thereby enabling the drawing of a desired planar shape. However, conventionally, similar to the formation of linear protrusions using laser light, the start and end points in inkjet printing were typically set to fixed positions in the film width direction (TD). Therefore, as with laser light, when a long film with knurled sections including the linear protrusions was wound up, the highest and lowest points of the wound long film could overlap. Consequently, conventional inkjet printing sometimes had an inferior ability to suppress blocking and wrinkle formation.

[0092] In contrast, in this embodiment, as in the first embodiment, the position of at least one of the highest and lowest points of each linear protrusion 710 of the knurled portion 700 is dispersed in the film width direction TD. Therefore, when a long film 50 is wound up to obtain a roll, at least one of the highest and lowest points of the long film 50 wound on the roll does not converge and overlap at a single position in the film width direction TD, but rather is dispersed and overlaps at multiple different positions. Consequently, the uniformity of the substantial thickness of the portion of the roll provided with the knurled portion 700 is improved. Therefore, the long films 50 can support each other with equal pressure over a wide area corresponding to the entire width of the knurled portion 700, thus improving the ability to suppress blocking and wrinkle formation.

[0093] Thus, a long film 50 having a knurled portion 700 including a linear protrusion 710 in which the position of at least one of the highest and lowest points is dispersed can be obtained by dispersing the positions of both the starting point and the ending point in the film width direction TD, just as in the first embodiment. Specifically, the long film according to the second embodiment is, A step of preparing a pre-processed film as a film before the formation of the knurled portion 700; A step of forming multiple knurled portions 700 on at least one surface of the film before processing, arranged in the longitudinal direction MD of the film; It can be manufactured by a manufacturing method that includes [the following].

[0094] In the step of forming knurled sections 700 on the surface of the film before processing, the knurled sections 700 are formed by inkjet printing. Therefore, the step of forming a single knurled section 700 includes, in this order, printing ink at the starting point to form a linear protrusion 710, printing ink in the intermediate section between the starting point and the ending point to form a linear protrusion 710, and printing ink at the ending point to form a linear protrusion 710. Furthermore, the formation of the knurled sections 700 by inkjet printing is usually performed while continuously transporting the film before processing in the longitudinal direction of the film, similar to the formation by laser light described in the first embodiment. Therefore, after the formation of one knurled section 700 is completed, the formation of the next knurled section 700 is started. Thus, in the manufacturing method of the long film 50 described above, the knurled sections 700 can be formed sequentially in the longitudinal direction MD of the film.

[0095] In this embodiment, as in the first embodiment, when manufacturing a plurality of knurled portions 700 arranged in the longitudinal direction MD of the film, the positions of both the starting point and the ending point are distributed to multiple different positions in the film width direction TD. This makes it possible to distribute at least one of the highest and lowest points of the linear protrusions 710 corresponding to the starting point or the ending point in the film width direction TD.

[0096] According to the long film 50 of this second embodiment, the same advantages as the long film 10 of the first embodiment can be obtained.

[0097] The long film 50 according to the second embodiment may be further modified. For example, it may be modified in the same way as the first embodiment or its modifications.

[0098] [4. Composition of long film] There are no restrictions on the material of the long film described above, but resin is usually used. In this case, the long film can be obtained as a long resin film. This resin film may be a stretched film or an unstretched film. Furthermore, the resin film may be a single-layer film comprising only a base layer, or a multi-layer film comprising any additional layer in combination with the base layer.

[0099] Typically, a resin-formed layer is used as the base layer. Various resins can be used depending on the application of the long film, but cyclic olefin resins and (meth)acrylic resins are preferred. Films with a base layer formed of cyclic olefin resin or (meth)acrylic resin generally tend to trap air during winding, and therefore have poor windability. In contrast, forming the knurled portion described above can improve windability, and furthermore, winding misalignment, winding tightness, winding looseness, and meandering can usually be effectively suppressed.

[0100] Cyclic olefin resins are resins containing cyclic olefin polymers. Cyclic olefin polymers exhibit excellent mechanical properties, heat resistance, transparency, low moisture absorption, dimensional stability, and lightweight properties.

[0101] A cyclic olefin polymer refers to a polymer whose structural units have an alicyclic structure. A cyclic olefin polymer can be a polymer with an alicyclic structure in the main chain, a polymer with an alicyclic structure in the side chains, a polymer with an alicyclic structure in both the main chain and side chains, or a mixture of two or more of these in any ratio. Among these, polymers with an alicyclic structure in the main chain are preferred from the viewpoint of mechanical strength and heat resistance.

[0102] Examples of alicyclic structures include saturated alicyclic hydrocarbon (cycloalkane) structures and unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structures. Of these, cycloalkane and cycloalkene structures are preferred from the viewpoint of mechanical strength and heat resistance, and cycloalkane structures are particularly preferred.

[0103] The number of carbon atoms constituting an alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, and particularly preferably 15 or less per alicyclic structure. When the number of carbon atoms constituting an alicyclic structure is within this range, the mechanical strength, heat resistance, and moldability of the resin are highly balanced.

[0104] In cyclic olefin polymers, 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 a cyclic olefin polymer is within this range, transparency and heat resistance are good.

[0105] Examples of cyclic olefin polymers include norbornene polymers, monocyclic cyclic olefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and their hydrides. Among these, norbornene polymers and their hydrides are particularly preferred due to their good moldability.

[0106] Examples of norbornene polymers and their hydrides include ring-opening polymers of monomers having a norbornene structure and their hydrides; and addition polymers of monomers having a norbornene structure and their hydrides. 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 other monomers copolymerizable thereto. Furthermore, 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 other monomers copolymerizable thereto. Among these, the hydrides of ring-opening polymers of monomers having a norbornene structure are particularly preferred from the viewpoint of moldability, heat resistance, low hygroscopicity, dimensional stability, and lightweight properties.

[0107] The weight-average molecular weight (Mw) of the cyclic olefin polymer is preferably 10,000 or more, more preferably 15,000 or more, particularly preferably 20,000 or more, preferably 100,000 or less, more preferably 80,000 or less, and 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 highly balanced.

[0108] The molecular weight distribution (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of the cyclic olefin polymer is preferably 1.2 or higher, more preferably 1.5 or higher, particularly preferably 1.8 or higher, preferably 3.5 or lower, more preferably 3.0 or lower, and particularly preferably 2.7 or lower. When the molecular weight distribution is above the lower limit of the above range, the productivity of the polymer can be increased and manufacturing costs can be suppressed. Furthermore, when it is below the upper limit, the amount of low molecular weight components is reduced, which can suppress relaxation during high-temperature exposure and improve the stability of the film.

[0109] The weight-average molecular weight and number-average molecular weight are the weight-average molecular weights in terms of polyisoprene or polystyrene, measured by gel permeation chromatography using cyclohexane as the solvent. However, if the sample does not dissolve in cyclohexane in the aforementioned gel permeation chromatography, toluene may be used as the solvent.

[0110] The glass transition temperature of the cyclic olefin polymer is preferably 130°C or higher, more preferably 135°C or higher, preferably 150°C or lower, and more preferably 145°C or lower. When the glass transition temperature is above the lower limit of the above range, the durability of the film at high temperatures can be improved. Furthermore, when the glass transition temperature is below the upper limit of the above range, stretching can be easily performed.

[0111] As the aforementioned cyclic olefin polymer, for example, one described in International Publication No. 2017 / 145718 may be used.

[0112] The proportion of the cyclic olefin polymer in the cyclic olefin resin is preferably 50% to 100% by weight, more preferably 70% to 100% by weight, and particularly preferably 90% to 100% by weight. When the proportion of the polymer is within the above range, sufficient heat resistance and transparency can be obtained.

[0113] The cyclic olefin resin may contain any components other than the cyclic olefin polymer, as long as they do not significantly impair the effects of the present invention. Examples of such components include colorants such as pigments and dyes; fluorescent whitening agents; dispersants; heat stabilizers; light stabilizers; ultraviolet absorbers; antistatic agents; antioxidants; lubricants; and the like. These may be used individually or in combination of two or more in any ratio.

[0114] (Meth)acrylic resin is a resin containing a (meth)acrylic polymer. A (meth)acrylic polymer refers to a polymer of acrylic acid or an acrylic acid derivative, and examples include polymers and copolymers of acrylic acid, acrylic acid esters, acrylamide, acrylonitrile, methacrylic acid, and methacrylic acid esters. Because (meth)acrylic polymers are strong and hard, films with high mechanical strength can be produced.

[0115] As the (meth)acrylic polymer, polymers containing structural units having a structure obtained by polymerizing (meth)acrylic acid esters are preferred. Examples of (meth)acrylic acid esters include alkyl esters of (meth)acrylic acid. Among these, compounds having a structure derived from (meth)acrylic acid and an alkanol or cycloalkanol having 1 to 15 carbon atoms are preferred. Furthermore, compounds having a structure derived from (meth)acrylic acid and an alkanol having 1 to 8 carbon atoms are even more preferred. By reducing the number of carbon atoms as described above, the elongation at the time of film breakage can be reduced.

[0116] Specific examples of acrylic acid esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, sec-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, and n-dodecyl acrylate.

[0117] Specific examples of methacrylate esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, n-decyl methacrylate, and n-dodecyl methacrylate.

[0118] Furthermore, the (meth)acrylic acid ester described above may have substituents such as hydroxyl groups or halogen atoms, as long as they do not significantly impair the effects of the present invention. Examples of (meth)acrylic acid esters having such substituents include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, and glycidyl methacrylate. These may be used individually or in combination of two or more in any ratio.

[0119] Furthermore, the (meth)acrylic polymer may be a polymer of acrylic acid or an acrylic acid derivative alone, or it may be a copolymer of acrylic acid or an acrylic acid derivative with any monomer copolymerizable thereto. Examples of arbitrary monomers include α,β-ethylenically unsaturated carboxylic acid ester monomers other than the (meth)acrylic acid esters mentioned above, as well as α,β-ethylenically unsaturated carboxylic acid monomers, alkenyl aromatic monomers, conjugated diene monomers, unconjugated diene monomers, carboxylic acid unsaturated alcohol esters, and olefin monomers. These may be used individually or in combination of two or more in any ratio.

[0120] When the (meth)acrylic polymer contains structural units having a structure obtained by polymerizing any monomer, the amount of structural units having a structure obtained by polymerizing any monomer in the (meth)acrylic polymer is preferably 50% by weight or less, more preferably 15% by weight or less, and particularly preferably 10% by weight or less.

[0121] Of these (meth)acrylic polymers, polymethacrylate is preferred, and polymethyl methacrylate is more preferred.

[0122] As the (meth)acrylic polymer mentioned above, for example, one described in International Publication No. 2017 / 145718 may be used.

[0123] The proportion of (meth)acrylic polymer in the (meth)acrylic resin is preferably 50% to 100% by weight, more preferably 70% to 100% by weight, and particularly preferably 90% to 100% by weight. When the proportion of polymer is within the above range, sufficient mechanical strength can be obtained.

[0124] The (meth)acrylic resin may contain any components other than the (meth)acrylic polymer, as long as they do not significantly impair the effects of the present invention. Examples of such components are similar to those that may be contained in the cyclic olefin resin. Furthermore, any component may be used individually or in combination of two or more components in any ratio.

[0125] When using a multilayer film comprising two or more layers as a long film, it is preferable that the multilayer film comprises 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, it is preferable that the functional layer is provided on the knurled side of the base layer, and it is even more preferable that 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. As the aforementioned functional layer, for example, one described in International Publication No. 2017 / 145718 may be used.

[0126] As described above, long films can be manufactured by a manufacturing method that includes the steps of preparing a pre-treatment film and forming knurled sections on the pre-treatment film to obtain a long film. There are no restrictions on the manufacturing method of the pre-treatment film. For example, when the resin film described above is used as the pre-treatment film, the pre-treatment film can be manufactured by a method that includes the step of forming the resin using an appropriate film molding method to obtain a base layer. Examples of film molding methods include casting, extrusion, and inflation molding. Among these, the melt extrusion method, which does not use solvents, is preferable from the viewpoint of the global environment, the working environment, and manufacturing efficiency, as it can efficiently reduce the amount of residual volatile components. As for the melt extrusion method, the inflation method using dies may be used, but the T-die method is preferred in terms of productivity and thickness accuracy.

[0127] Furthermore, when manufacturing a pre-treatment film that includes a functional layer in combination with a base layer, the manufacturing method of the pre-treatment film may include a step of forming the functional layer on the base layer after the step of obtaining the base layer.

[0128] [5. Uses of long film rolls] Long films can be used for a wide range of applications, and are particularly preferred for use as optical films. Examples of optical films include phase difference films, polarizing plate protective films, and optical compensation films. Among these, the long films mentioned above are particularly preferred for use as polarizing plate protective films.

[0129] A polarizing plate typically comprises a polarizer and a polarizing plate protective film. Therefore, when the aforementioned long film is used as the polarizing plate protective film, it is usually used by laminating the long film onto the polarizer.

[0130] When bonding a long film to a polarizer, the film and polarizer may be bonded directly without an adhesive, or they may be bonded with an adhesive. Furthermore, the long film may be bonded to only one side of the polarizer, or to both sides. If the long film is bonded to only one side of the polarizer, a different, highly transparent film may be bonded to the other side of the polarizer.

[0131] As a polarizer, for example, a film manufactured by adsorbing iodine or a dichroic dye onto a polyvinyl alcohol film and then uniaxially stretching it in a boric acid bath may be used. Alternatively, as a polarizer, a film manufactured by adsorbing iodine or a dichroic dye onto a polyvinyl alcohol film, stretching it, and then modifying some of the polyvinyl alcohol units in the molecular chain into polyvinylene units may be used. Furthermore, as a polarizer, a polarizer having the function of separating polarized light into reflected light and transmitted light may be used, for example, a grid polarizer, a multilayer polarizer, or a cholesteric liquid crystal polarizer. Among these, a polarizer containing polyvinyl alcohol is preferred. The degree of polarization of the polarizer is preferably 98% or higher, more preferably 99% or higher. The average thickness of the polarizer is preferably 5 μm to 80 μm.

[0132] An optically transparent adhesive can be used to bond the long film and the polarizer. Examples of adhesives include water-based adhesives, solvent-based adhesives, two-component curing adhesives, photocuring adhesives, and pressure-sensitive adhesives. Among these, water-based adhesives and photocuring adhesives are preferred, and polyvinyl alcohol-based water-based adhesives are particularly preferred. As an adhesive, for example, one described in International Publication No. 2017 / 145718 can be used. Furthermore, one type of adhesive may be used alone, or two or more types may be used in any ratio.

[0133] When bonding a polarizer and a long film using an adhesive, the adhesive may be cured after bonding the polarizer and the long film via the adhesive, if necessary. The method of curing the adhesive can be appropriate depending on the type of adhesive. For example, when using a photocurable adhesive, the adhesive can be cured by irradiation with active energy rays such as ultraviolet light.

[0134] When an adhesive is used, an adhesive layer is provided between the polarizer and the long film. The average thickness of this adhesive layer is preferably 0.05 μm or more, more preferably 0.1 μm or more, preferably 5 μm or less, and more preferably 1 μm or less. [Explanation of Symbols]

[0135] 10 Long film Surface of 10U long film 20 long rolls of film 30 long rolls of film 40 long rolls of film 50 long rolls of film 51 Substrate film layer 51U Surface of the substrate film layer 100 Naru section 110 Linear protrusion 110H Highest point of the linear convex section 110S Starting point of the linear protrusion 110M intermediate part of the linear protrusion 110E End point of the linear protrusion 111 Corner 112 Straight section 120 recess 200 Naru section 210 Linear protrusion 210S Starting point of the linear protrusion 210E End point of the linear protrusion 300 Naru section 310 Linear protrusion 310S Starting point of the linear protrusion 310E End point of the linear protrusion 313 Part of the linear protrusion 400 Naru section 410 Linear protrusion 410H Highest point of the linear convex section 410S Starting point of the linear protrusion 410E End point of the linear protrusion 500 Naru section 510 Linear protrusion 510H Highest point of the linear convex section 510S Starting point of the linear protrusion 510E End point of the linear protrusion 600 Naru section 610 Linear protrusion 700 Naru section 710 Linear protrusion

Claims

1. A long film having multiple knurled portions on at least one surface, each containing a continuous linear protrusion when viewed from the thickness direction, The knurled portions are formed in a line along the longitudinal direction of the film, The knurled parts are arranged in a regular pattern. The position of at least one of the highest point and lowest point of each of the knurled portions is dispersed in the film width direction. A long film in which the number of positions where the highest point is dispersed is four or more, or the number of positions where the lowest point is dispersed is four or more.

2. The long film according to claim 1, wherein the knurled portion includes a recess and protrusions provided on both sides of the recess.

3. A long film having a plurality of knurled portions on at least one surface, each containing a linear protrusion that is continuous when viewed in the thickness direction, The knurled portions are formed in a line along the longitudinal direction of the film, The position of at least one of the highest point and lowest point of each of the knurled portions is dispersed in the film width direction. The long film comprises a base film layer and the protrusions attached to the surface of the base film layer.

4. The process of preparing the film before processing, The process includes the step of forming multiple knurled portions, each containing a continuous linear protrusion when viewed from the thickness direction, on at least one surface of the pre-processed film, such that they are aligned in the longitudinal direction of the film and arranged in a regular manner. The process of forming the knurled portion includes, in this order, forming the protrusion at the starting point, forming the protrusion in the intermediate portion between the starting point and the ending point, and forming the protrusion at the ending point. The positions of both the starting point and the ending point are dispersed in the film width direction. A method for manufacturing a long film, wherein the number of positions where the starting point and the ending point are dispersed is four or more.

5. The method for manufacturing a long film according to claim 4, wherein in the step of forming the knurled portion, the knurled portion is formed by laser light.

6. A step of preparing a film before processing, The process includes forming a plurality of knurled portions, each containing a continuous linear protrusion when viewed from the thickness direction, on at least one surface of the pre-processed film, arranged in the longitudinal direction of the film. The process of forming the knurled portion includes, in this order, forming the protrusion at the starting point, forming the protrusion in the intermediate portion between the starting point and the ending point, and forming the protrusion at the ending point. The positions of both the starting point and the ending point are dispersed in the film width direction. A method for manufacturing a long film, wherein, in the step of forming the knurled portion, the knurled portion is formed by inkjet printing.

Images