Method and apparatus for manufacturing optical film laminate having no protuberance in laser cut part

Abstract

Provided is a method for manufacturing an optical film laminate in which protuberances are substantially not generated at an end part of a cut portion even when cut by a laser beam. In this method, a starting material laminate is conveyed that is obtained by laminating a first resin film onto one surface of an optical functional layer including one or a plurality of films and laminating a second resin film onto the other surface. A first base material is laminated onto the first resin film of the starting material laminate, and a second base material is laminated onto the second resin film, thereby obtaining a starting material laminate with base materials on both sides. The starting material laminate, the first base material, the second base material, or the starting material laminate with base materials on both sides, or a plurality of these, are charged with static electricity to closely adhere the first base material and second base material to the starting material laminate, after which a cut surface of any shape is formed in the starting material laminate by using a laser beam. Static electricity is removed from the starting material laminate with base materials on both sides, and the first base material and the second base material are peeled from one or a plurality of optical film laminates having the cut surface of any shape.

Description

Manufacturing method and manufacturing device for optical film laminate with no raised portion at laser cut section

[0001] The present invention relates to a manufacturing technology for optical film laminates, and more specifically to a method and apparatus for manufacturing an optical film laminate in which substantially no protrusions are generated at the edges of the cut portions by cutting an optical film laminate before cutting with laser light while base films are electrostatically adhered to both sides of the optical film laminate.

[0002] Optical display devices such as liquid crystal display devices and organic EL display devices use various optical film laminates such as polarizing films and retardation films. Conventional optical film laminates are manufactured through a number of different processes depending on the application and shape of the final product.

[0003] For example, in the manufacturing process of optical film laminates for smartphones, a long web-like laminate having a predetermined width in which multiple films are laminated is fed out and cut to a predetermined length using a circular blade, thereby obtaining multiple rectangular optical film laminates. Alternatively, in the manufacturing process of optical film laminates for in-vehicle applications and smartwatches, for which demand has been increasing in recent years, a long web-like laminate having a predetermined width is fed out and punched out using a Thomson die, thereby obtaining multiple optical film laminates of any desired shape. In either process, a sheet-like laminate may be used instead of the long web-like laminate, or a sheet-like mother laminate from which multiple optical film laminates can be obtained from a single sheet may be used. The multiple optical film laminates obtained in this manner are stacked, edge-treated as necessary, packaged, and shipped.

[0004] However, if various processes are adopted according to the use and shape of the final product, different manufacturing equipment must be introduced for each use and shape, and individual measures must be taken for each manufacturing equipment, which results in increased manufacturing costs. Therefore, it is desirable to realize a unified manufacturing process regardless of the use and shape of the final product. In order to realize a unified manufacturing process, it is preferable to adopt a method of cutting the laminate using laser light instead of a circular blade or Thomson die.

[0005] When a long web-like or sheet-like laminate is cut with a laser beam, protuberances (protuberances) may occur at the edges of the cut laminate, or fumes (fine dust particles formed by condensation of vapor generated during melting) may adhere to the edges. If protuberances occur at the edges, when multiple optical film laminates are stacked with their edges aligned, the protuberances of each optical film laminate may become misaligned with respect to each other, or problems may occur in image recognition. This may result in problems with packaging during shipping, problems during alignment for bonding to liquid crystal cells or organic EL cells in later processes, and problems when removing optical film laminates one by one from a stack of multiple stacked optical film laminates.

[0006] Furthermore, for example, when peeling a surface protective film from an optical film laminate having the surface protective film in a later step, the surface protective film can usually be peeled off by pulling up a release tape attached to its surface. However, if there is a protrusion at the end of the optical film laminate (in this case, the end of the surface protective film), the contact area between the end of the release tape and the surface of the surface protective film becomes smaller than when there is no protrusion, and there are cases where the surface protective film cannot be peeled off even when the release tape is pulled up.

[0007] Patent Document 1 proposes a method for removing fumes generated when cutting a multilayer optical film with laser light, but does not disclose the occurrence of protrusions at the edge of the cut laminate when cutting a multilayer optical film with laser light, or a means for solving this problem.

[0008] Special Publication No. 2005-526992

[0009] In view of the above problems, the present invention aims to provide a method and an apparatus for manufacturing an optical film laminate in which, even when cut by laser light, no protrusions are substantially generated at the end of the cut portion.

[0010] The inventors have discovered that by laminating a base film on both sides of a laminate (raw material laminate) before it is cut with laser light, charging the two together using static electricity to bring them into close contact, and then cutting with laser light, substantially no raised portions are generated at the ends of both sides on which the base film is laminated.

[0011] In one aspect, the present invention provides a method for producing an optical film laminate of any shape, in which a first resin film is laminated on one side of an optical functional layer containing one or more films and a second resin film is laminated on the other side. In this method, first, a raw material laminate is transported, in which a first resin film is laminated on one side of an optical functional layer containing one or more films and a second resin film is laminated on the other side. Next, a first substrate is laminated on the first resin film of the raw material laminate, and a second substrate is laminated on the second resin film to obtain a raw material laminate with double-sided substrates. Next, static electricity is applied to the raw material laminate, the first substrate, the second substrate, or the raw material laminate with double-sided substrates, or a combination thereof, thereby bringing the first substrate and the second substrate into close contact with the raw material laminate, and then a cut surface of any shape is formed on the raw material laminate using laser light. The process then proceeds to remove static electricity from the raw material laminate with double-sided substrates, and peel off the first substrate and the second substrate from one or more optical film laminates having cut surfaces of any shape.

[0012] In another aspect, the present invention provides an apparatus for producing an optical film laminate of any shape, in which a first resin film is laminated on one side of an optical functional layer including one or more films, and a second resin film is laminated on the other side. The apparatus includes a conveying device that conveys a raw material laminate in which a first resin film is laminated on one side of an optical functional layer including one or more films and a second resin film is laminated on the other side; a lamination device that laminates a first substrate on the first resin film of the raw material laminate and a second substrate on the second resin film to produce a raw material laminate with double-sided substrates; a charging device that charges the raw material laminate, the first substrate, the second substrate, or the raw material laminate with double-sided substrates, or a plurality of these, with static electricity in order to adhere the first substrate and the second substrate to the raw material laminate; a laser cutting device that cuts the raw material laminate with double-sided substrates to form one or more optical film laminates of any shape; a static elimination device that removes static electricity from the raw material laminate with double-sided substrates; and a peeling device that peels the first substrate and the second substrate from the one or more optical film laminates of any shape.

[0013] 1A and 1B are schematic cross-sectional views of an optical film laminate produced according to one embodiment of the present invention, in which (a) is an optical film laminate that has no raised portions at the edges of the cut portion even when cut using laser light, and (b) is a schematic cross-sectional view showing the state of a raw material laminate cut by laser light.

[0023] Fig. 1 is a conceptual diagram of a process for producing an optical film laminate that has substantially no raised portions at the edges of the cut portion.

[0024] Fig. 1 is a conceptual diagram of an apparatus for producing an optical film laminate that has substantially no raised portions at the cut portion according to a first embodiment, showing an apparatus in which web-like base films are laminated on both sides of a sheet-like raw material laminate and electrostatically charged to perform cutting.

[0025] Fig. 1 is a conceptual diagram of an apparatus for producing an optical film laminate that has substantially no raised portions at the cut portion according to a second embodiment, showing an apparatus in which web-like base films are laminated on both sides of a web-like raw material laminate and electrostatically charged to perform cutting.

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0015] (Configuration of optical film laminate without protrusions) Figure 1 shows a schematic cross-sectional view of an optical film laminate according to one embodiment of the present invention, in which edges cut with laser light have substantially no protrusions. Figure 1(a) is a schematic cross-sectional view of an optical film laminate F1 in which neither surface 11 nor surface 13 has substantially no protrusions. Figure 1(b) is a schematic cross-sectional view showing a state in which a raw material laminate RM has been cut with laser light.

[0016] Here, the optical film laminate "substantially free of protrusions" in this specification does not only refer to an optical film laminate that has no protrusions at all at the edge cut by the laser beam (i.e., the height of the protrusions is 0 μm), but also includes an optical film laminate that has protrusions, even if they are present, that are so slight that they do not cause the problems described above that are caused by protrusions, i.e., misalignment during lamination, problems during image recognition, problems with peeling of the surface protection film when the peeling tape is pulled up, etc. (typically, the height of the protrusions is 10 μm or less, but is not limited to this).

[0017] The optical film laminate F1 can be produced by the manufacturing method according to the present invention, which will be described later. For example, the optical film laminate F1 can be obtained by laminating base films BF1 and BF2 on both sides of a web-like raw laminate RM, charging the raw laminate RM with static electricity to bring the base films BF1 and BF2 into close contact with each other, and then cutting the laminate using laser light. Figure 1(a) shows the cut portion as viewed from the side (as viewed from diagonally below and to the left of Figure 1(b)). The parts designated by the reference numbers in Figure 1(b) correspond to those in Figure 1(a).

[0018] The optical film laminate F1 is a laminate in which a surface protective film PF is laminated on one side of a polarizing film POL and a release liner RL is laminated on the other side. Although this configuration of optical film laminate is described as an example in this specification, the optical film laminate to which the present invention can be applied is not limited to this. For example, the optical film laminate may have an optical functional layer composed of multiple films instead of a polarizing film. Furthermore, the optical film laminate may be a laminate in which a release liner RL is laminated on one side of the optical functional layer and surface protective films PF are laminated on multiple sides. The optical functional layer may be, for example, a polarizing film, a retardation film, a combination of a polarizing film and a retardation film, an OCA (Optical Clear Adhesive), a combination of a polarizing film and an OCA, a PET film, or the like. Alternatively, the optical film laminate can be, for example, a laminate in which a light release liner is laminated on one side of an OCA and a heavy release liner is laminated on the other side, or a laminate in which a light release liner is laminated on one side of a PET film and a heavy release liner is laminated on the other side.

[0019] The optical film laminate F1 can be cut into a laminate having any shape from, for example, a web-like raw material laminate RM using laser light. Arbitrary shapes include not only rectangular, circular, elliptical, and other shapes, but also irregular shapes. Irregularly shaped laminates can include laminates with special shapes, such as a rectangular shape having a notch or recess (a so-called notch) on one side, a semi-cylindrical shape used in automotive instrument panels, or a rectangular film with a circular or rectangular hole in part. For example, in the case of a rectangular laminate having a notch or recess (a so-called notch) on one side, the cut surface formed by the laser light will be formed not only on each side but also inside the notch or recess.

[0020] The optical film laminate F1 has substantially no raised portion at the edge 11a of the surface 11 on the surface protective film PF side, nor at the edge 13a of the surface 13 of the release liner RL. The edge 11a includes the edge 11b (FIG. 1(c)) of the cut portion of the surface 11 of the optical film laminate F1 and the area adjacent to it. The same is true for the edge 13a.

[0021] In the method for manufacturing an optical film laminate according to the present invention, as described below, before cutting the raw laminate RM with laser light, a base film BF1 is laminated on the surface 11 facing the surface protective film PF, and a base film BF2 is laminated on the surface 13 facing the release liner RL to form a raw laminate RMB with double-sided substrates, and the raw laminate RMB with double-sided substrates is then charged with static electricity. The static electricity causes the surface 11 of the surface protective film PF of the raw laminate RM to adhere to the base film BF1, and the surface 13 of the release liner RL to adhere to the base film BF. Therefore, when the raw laminate RMB with double-sided substrates is cut in this state, substantially no protrusions are formed on either surface 11 or surface 13 of the raw laminate RM. Furthermore, no fumes are generated on surfaces 11 and 13. Here, "adhesion" refers to a state in which there is no air layer or air pocket between the two films, and no air layer or air pocket is formed even during transport. If surface 11 of the surface protection film PF and the base film BF1 are in complete contact, and surface 13 of the release liner RL and the base film BF2 are in complete contact, there is no space for physical protrusions to occur, and the heat generated during cutting with laser light is not easily conducted to the base film BF, causing the surface temperature to rise, so no protrusions are substantially generated on surfaces 11 and 13.

[0022] The optical film laminate F1 has an end surface 15, which is a cut surface cut by laser light. The end surface 15 is located between an edge 11b of the surface 11 and an edge 13b of the surface 13 of the optical film laminate F1. Due to the characteristics of forming a cut surface by laser light, the end surface 15 is typically an inclined surface, but is not limited to this and may be a surface perpendicular to the surfaces 11 and 13. Although the end surface 15 is depicted as a flat surface in FIG. 1( a), it is not limited thereto and may be a curved surface or a combination of a flat surface and a curved surface when the optical film laminate F1 is to have an arbitrary shape depending on the application.

[0023] (Process for manufacturing an optical film laminate according to the present invention) Figure 2 is a conceptual diagram of a process for manufacturing an optical film laminate F1 that is substantially free of protrusions. In Figure 2(a), a base film BF1 is laminated on one side of a raw material laminate RM, and a base film BF2 is laminated on the other side to obtain a raw material laminate RMB with double-sided base materials. The raw material laminate RM is a laminate in which a surface protective film PF is laminated on one side of a polarizing film POL, and a release liner RL is laminated on the other side, and may be in the form of either a web or a sheet.

[0024] The base films BF1 and BF2 (collectively referred to as base film BF) may be made of a non-adhesive material without an adhesive layer, or may be made of an adhesive material. Both base films BF1 and BF2 may be made of a non-adhesive material or an adhesive material, or one may be made of a non-adhesive material and the other of an adhesive material. In the manufacturing method according to the present invention, the raw material laminate RM and the base film BF are adhered together using static electricity, so a non-adhesive material can be used for the base film BF. Therefore, for example, it is possible to reuse the base film BF2 used in the process of manufacturing the optical film laminate according to the present invention, or to use waste material used in other processes or products, thereby reducing the amount of base film used and reducing manufacturing costs. The non-adhesive base film BF that can be used in the present invention may be any film that is difficult to stretch even when tension is applied. For example, a polyethylene terephthalate (PET) film, a polyethylene film, or the like can be used as the base film BF.

[0025] On the other hand, if an adhesive material is used as the base film BF, the raw laminate RM and the base film BF can be more firmly adhered to each other, making it possible to more effectively prevent the occurrence of protrusions on the surface where the base film BF is laminated. However, if an adhesive material is used, it is difficult to reuse a used base film BF, which increases the amount of material used and may therefore increase manufacturing costs. Furthermore, if the adhesive strength of the material used is greater than the adhesive strength between the individual films of the raw laminate RM, the base film BF may not be peeled off or the films of the raw laminate RM may peel off, thereby limiting the base film BF that can be used. Therefore, it is preferable that the adhesive base film BF be a weakly adhesive material, and for example, a surface protection material AW303EB manufactured by Nitto Denko Corporation may be used.

[0026] Next, as shown in FIG. 2( b), a double-sided base-supported raw laminate RMB, which is a laminate of the raw laminate RM and the base films BF1 and BF2, is electrostatically charged (40). Charging the raw laminate RM with static electricity allows the raw laminate RM and the base film BF to be tightly attached (FIG. 2( c)). As shown in FIGS. 2( b) and 2( c), even if the raw laminate R has a protruding portion V1 toward the base film BF1, the protruding portion V1 can be eliminated by charging the raw laminate RM with static electricity to tightly attach the raw laminate RM to the base film BF1. Furthermore, even if the raw laminate RM has a portion V2 separated from the surface of the base film BF2, the separated portion V2 can be eliminated by charging the raw laminate RM with static electricity to tightly attach the raw laminate RM to the base film BF2. Electrostatic charging is not limited to being performed on the double-sided base material-attached raw material laminate RMB, but may also be performed on the raw material laminate RM before it is laminated with the base films BF1 and BF2, or on the base films BF1 and / or BF2 before they are laminated on the raw material laminate RM. Although not shown, when electrostatically charging the double-sided base material-attached raw material laminate RMB, it is preferable to bring the portion of the double-sided base material-attached raw material laminate RMB to be charged into contact with a conductor such as a metal roller, and to place a charging device on the opposite side of the metal roller so as to face the contacting portion.

[0027] It is preferable that the raw material laminate RM and the base films BF1 and BF2 are uniformly charged with static electricity over their entire surfaces. The amount of static electricity to be charged is such that the base films BF1 and BF2 and the raw material laminate RM do not peel (do not lose adhesion) during transport and when the cut surface is formed by the laser beam 41. The amount of static electricity is preferably −10 kV or more and −0.5 kV or less, or 0.5 kV or more and 10 kV or less, more preferably −4.0 kV or more and −0.5 kV or less, or 0.5 kV or more and 4.0 kV or less, and most preferably −4.0 kV or more and −0.5 kV or less. If the amount of static electricity is less than −10 kV or more than +10 kV, the effect of suppressing the occurrence of protrusions is increased, but problems such as attraction of foreign matter, incomplete removal of static electricity and poor peeling, and adverse effects on peripheral devices due to atmospheric discharge occur.If the amount of static electricity is more than −0.5 kV and less than +0.5 kV, the adhesion is weak, and there is a problem that voids are generated by the impact when irradiated with laser light.

[0028] 2(c), after static electricity is charged, the raw material laminate RMB with double-sided substrates is cut using laser light 41 to form an optical film laminate F1. Here, cutting with laser light 41 is performed by irradiating the laser light 41 from the side of the base film BF1 of the raw material laminate RMB with double-sided substrates, but this is not limited thereto and the laser light 41 can also be applied from the side of the base film BF2. The intensity of the laser light 41 is preferably set so that it reaches a depth that cuts the surface protective film PF, polarizing film POL, and release liner RL but does not cut the base film BF1 or BF2 on the opposite side from the light source of the laser light 41.

[0029] As described above, cutting by the laser light 41 is performed linearly when the required shape of the optical film laminate F1 is rectangular, but may also be performed curvedly when the shape of the optical film laminate F1 is any shape.

[0030] Next, as shown in FIG. 2( d ), after cutting with laser light 41, static electricity is removed from the raw material laminate RMB with double-sided substrates ( 42 ). By removing static electricity, the adhesive state between the raw material laminate RM and the base films BF1 and BF2 is released. On both sides of the cut portion of the base film BF1 by laser light 41, the base film BF1 may melt due to the heat generated during cutting, rising to the surface and solidifying, forming raised portions 12. If protruding portions V1 or separated portions V2 existed before charging, these portions may separate or protrude again. When removing static electricity, it is preferable to remove static electricity from the raw material laminate RMB with double-sided substrates while it is not in contact with anything, as opposed to charging.

[0031] Next, as shown in FIG. 2( e), the base film BF1 is peeled off from the surface of the optical film laminate F1. The edge 11a of the cut portion of the optical film laminate F1 that was covered by the base film BF1 is free of raised portions. Finally, as shown in FIG. 2( f), the portion corresponding to the optical film laminate F1 is peeled off from the base film BF2, thereby obtaining an optical film laminate F1 that is substantially free of raised portions at its edge. When non-adhesive materials are used for the base films BF1 and BF2, the release liner RL can be easily peeled off from the base films BF1 and BF2 by discharging the charges. On the other hand, if an adhesive material is used for either or both of the base films BF1 and BF2, depending on the adhesive strength, even after discharging, when attempting to peel the optical film laminate F1 from the base film BF1 or BF2, for example, the release liner RL and the base film BF1 or BF2 may not be peeled properly, and peeling may occur between the release liner RL and the polarizing film POL, with the release liner RL remaining on the base film BF1 or BF2. Therefore, when adhesive base films BF1 and / or BF2 are used, it is preferable that their adhesive strength is smaller than that of the release liner RL and / or the surface protective film.

[0032] (Apparatus for Producing an Optical Film Laminate Without Protuberances) [First Embodiment] Fig. 3 is a conceptual diagram of an apparatus 60 for producing an optical film laminate that is substantially free of protuberances, according to Embodiment 1. Apparatus 60 is a sheet-web type apparatus that laminates web-like base films BF1 and BF2 on a sheet-like raw material laminate RM to form a web-like raw material laminate RMB with double-sided base materials, and then charges the raw material laminate RMB with double-sided base materials and cuts it with laser light.

[0033] The apparatus 60 includes a conveying device 61 that removes a sheet-like raw material laminate RM from, for example, a stocker and conveys it to a lamination device 62 with base films BF1 and BF2. A suction pickup device, a conveying roller, or the like known to those skilled in the art can be appropriately used as the conveying device 61. In the apparatus 60, a plurality of sheet-like raw material laminates RM are continuously laminated lengthwise between web-like base films BF1 and BF2 to form a web-like double-sided base material-attached raw material laminate RMB. For this purpose, the apparatus 60 is configured such that the web-like base films BF1 and BF2, unwound from the base film rolls BFR1 and BFR2, respectively, are conveyed to the lamination device 62 that laminates the raw material laminate RM and the base films BF1 and BF2.

[0034] In the laminating device 62, the sheet-like raw material laminate RM and the web-like base films BF1 and BF2 are passed between a pair of laminating rollers 62a to form a web-like double-sided base material-attached raw material laminate RMB in which the sheet-like raw material laminate RM is sandwiched between the web-like base films BF1 and BF2. As the laminating roller 62a, a laminating roller well known to those skilled in the art for laminating two resin films with an adhesive can be appropriately used.

[0035] The apparatus 60 includes a charging device 63 downstream of the laminating device 62. The charging device 63 charges the double-sided base material-attached raw material laminate RMB with static electricity, thereby electrostatically bonding the raw material laminate RM to the base films BF1 and BF2. Any charging device known to those skilled in the art can be used as the charging device 63, such as the JPK-3 manufactured by Kasuga Electric Co., Ltd. In FIG. 3 , the charging device 63 is disposed downstream and above the laminating device 62. Therefore, in the apparatus 60, static electricity is applied from the base film BF1 side of the double-sided base material-attached raw material laminate RMB, thereby electrostatically bonding the raw material laminate RM to the base films BF1 and BF2. However, the location of the charging device 63 is not limited thereto; the charging device 63 may be disposed upstream of the laminating device 62 near the base film BF1 or BF2. In this case, the base film BF1 or BF2 is charged with static electricity before being laminated on the raw material laminate RM, so that the raw material laminate RM and the base films BF1 and BF2 come into close contact with each other when they are laminated in the lamination device 62. Alternatively, the charging device 63 may be located upstream of the lamination device 62 and near the raw material laminate RM. In this case, the raw material laminate RM is charged with static electricity before being laminated, so that the base film BF1 or BF2 comes into close contact with the raw material laminate RM when they are laminated in the lamination device 62. Alternatively, the charging device 63 may be located in multiple locations. For example, the charging devices may be located both upstream and downstream of the lamination device 62, or may be located downstream of the lamination device 62 on both the base film BF1 side and the base film BF2 side.

[0036] The charged web-like raw material laminate RMB with double-sided substrates is transported by a transport device 64 known to those skilled in the art so that it passes over a pedestal 65. Any pedestal known to those skilled in the art can be used as the pedestal 65, but it is preferably an adsorption pedestal so that the raw material laminate RMB with double-sided substrates placed thereon will not move during laser cutting.

[0037] The raw material laminate RMB with double-sided substrates is stopped once on the base 65 and cut by laser light from the laser cutting device 66. The laser cutting device 66 may have, for example, a laser light generating unit that generates laser light and can irradiate the raw material laminate RMB with double-sided substrates placed on the base 65, and a moving unit that moves the laser light generating unit so as to cut the raw material laminate RMB with double-sided substrates into a desired shape. The laser cutting device 66 may be any device used for cutting resin films and known to those skilled in the art.

[0038] The intensity of the laser light is preferably set so as to reach a depth that cuts the base film BF1, surface protective film PF, polarizing film POL, and release liner RL contained in the double-sided base material laminate RMB but does not cut the base film BF2. The laser cutting device 66 can cut the base film RM contained in the double-sided base material laminate RMB to form multiple optical film laminates F1 of any shape between the base films BF1 and BF2. At this point, the base film BF1 cut to the same shape as the optical film laminate F1 is in close contact with the surface protective film PF of the optical film laminate F1.

[0039] The cut raw material laminate RMB with double-sided substrates is neutralized by a neutralization device 67. The neutralization device 67 is a device for removing static electricity from the charged raw material laminate RMB with double-sided substrates. As the neutralization device 67, any neutralization device known to those skilled in the art can be used as appropriate, and for example, the JPK-3 manufactured by Kasuga Electric Co., Ltd. can be used as the neutralization device 67.

[0040] In the double-sided substrate-attached raw material laminate RMB including the optical film laminate F1 from which static electricity has been removed by the static eliminator 67, the tight contact state between the raw material laminate RM and the optical film laminate F1 and the base films BF1 and BF2 has been released, and the optical film laminate F1 can be easily peeled from the base films BF1 and BF2. The apparatus 60 includes a peeling device 68 downstream of the static eliminator 67 to peel the optical film laminate F1 from the base films BF1 and BF2.

[0041] The peeling device 68 has a pickup device 68a, known to those skilled in the art, for removing the base film BF1 laminated on the surface protective film PF side. The base film BF1 and the underlying surface protective film PF are released from contact by discharging electricity, allowing the base film BF1 to be easily picked up. The peeling device 68 has a peeling roller (or peeling bar) 68b downstream of the pickup device 68a, and the remaining base film BF1 (which has holes formed therein with the same shape as the optical film laminate F1) is pulled via the peeling roller 68b in a direction away from the conveyance direction of the double-sided base material laminate RMB (upward in FIG. 3 ). Thus, the remaining base film BF1 is peeled from the optical film laminate F1 and taken up.

[0042] Another peeling roller (or peeling bar) 68c is provided further downstream of the peeling roller (or peeling bar) 68b, and the base film BF2 on the release liner RL side is pulled via the peeling roller 68c in a direction away from the conveyance direction of the double-sided base material laminate RMB (downward in FIG. 3 ). Thus, the base film BF2 is peeled off from the optical film laminate F1 and taken up.

[0043] The remaining portion RMR of the raw laminate from which the optical film laminate F1 has been cut is released from its intimate contact with the base film BF2 by being neutralized, and is therefore separated from the base film BF2 when the base film BF2 is taken up, and is, for example, dropped and collected. Meanwhile, the optical film laminate F1 is sent out of the peeling device 68 without changing the conveying direction by the peeling rollers 68b, 68c, and is removed by a conveying device 69 or the like that is well known to those skilled in the art. In this manner, optical film laminates F1 having one or more arbitrary shapes can be obtained.

[0044] Second Embodiment Fig. 4 is a conceptual diagram of an apparatus 70 for manufacturing an optical film laminate substantially free of protrusions according to a second embodiment. The apparatus 70 is a web-web type apparatus that laminates web-like base films BF1 and BF2 on a web-like raw material laminate RM to form a web-like raw material laminate RMB with double-sided base materials, and then charges the raw material laminate RMB with double-sided base materials and cuts it with laser light. The following mainly describes the configuration that differs from the apparatus 60 of embodiment 1.

[0045] In the apparatus 60 of embodiment 1, a plurality of sheet-like raw material laminates RM are continuously laminated between web-like base films BF1 and BF2 to form a web-like raw material laminate RMB with double-sided base materials. In contrast, in the apparatus 70, web-like base films BF1 and BF2 are laminated on both sides of the web-like raw material laminate RM to form a web-like raw material laminate RMB with double-sided base materials. For this reason, the apparatus 70 is configured so that the web-like raw material laminate RM unwound from the raw material laminate roll RMR is transported to a lamination device 72 that laminates the raw material laminate RM and the base films BF1 and BF2.

[0046] In the lamination device 72, by passing a web-shaped raw material laminate RM and web-shaped base films BF1 and BF2 between a pair of lamination rolls 72a, a web-shaped double-sided base material-attached raw material laminate RMB can be formed in which the web-shaped raw material laminate RM is sandwiched between the web-shaped base films BF1 and BF2.

[0047] The device 70 includes a charging device 73 downstream of the laminating device 72. The charging device 73 charges the double-sided base material-attached raw material laminate RMB with static electricity, thereby electrostatically bonding the raw material laminate RM to the base films BF1 and BF2. As with the device 60, the location of the charging device 73 is not limited thereto, and one or more charging devices 73 can be disposed in any desired location.

[0048] The charged web-like raw material laminate RMB with double-sided substrates is transported by a transport device 74 and cut with laser light on a base 75. The cut raw material laminate RMB with double-sided substrates is then neutralized by a static eliminator 77. The transport device 74, base 75, laser cutting device 76, and static eliminator 77, as well as their functions, can be similar to those of the device 60.

[0049] In the double-sided substrate-attached raw material laminate RMB including the optical film laminate F1 from which static electricity has been removed by the static eliminator 77, the tight contact state between the raw material laminate RM and the optical film laminate F1 and the base films BF1 and BF2 has been released, and the optical film laminate F1 can be easily peeled from the base films BF1 and BF2. The apparatus 70 also includes a peeling device 78 downstream of the static eliminator 77 to peel the optical film laminate F1 from the base films BF1 and BF2.

[0050] The peeling device 78 can be configured to include a pickup device for removing the base film BF1 cut to the same shape as the optical film laminate F1, similar to the peeling device 68, but a different configuration will be described here. Note that the configuration described below can also be employed in the peeling device 68.

[0051] In the peeling device 78, the cut base film BF1 and the remaining portion of the base film BF1 are joined using tape TP, and then the cut base film BF1 and the remaining portion of the base film BF1 are peeled off from the optical film laminate F1 together with the tape TP. The tape TP is unwound from the tape roll TPR with its adhesive side facing the base film BF1. In the bonding section 78a, the unwound tape TP is bonded to the base film BF1 of the double-sided base material laminate RMB from which static electricity has been removed by the static eliminator 77. The position at which the tape TP is bonded is not limited as long as it can bond the cut base film BF1 and the remaining portion of the base film BF1. In the example of FIG. 4, three cut base films BF1 are lined up in the width direction of the double-sided base material laminate RMB, and three narrow strips of tape TP are shown being unwound from the roll TPR to connect them to the remaining portion of the base film BF1.

[0052] A peeling roller (or peeling bar) 78b is provided downstream of the laminating section 78a, and the base film BF1 connected with the tape TP is pulled via the peeling roller 78b in a direction away from the conveyance direction of the double-sided base material laminate RMB (upward in FIG. 4 ). Thus, the base film BF1 connected with the tape TP is peeled off from the optical film laminate F1 and taken up by the take-up roller.

[0053] Another peeling roller (or peeling bar) 78c is provided downstream of the peeling roller 78b. The remaining portion RMR of the web-like raw material laminate RM from which the optical film laminate F1 has been cut is released from its tight contact with the base film BF2 by being neutralized, and is pulled away from the conveyance direction (upward in FIG. 4 ) via the peeling roller 78c and taken up. Another peeling roller (or peeling bar) 78d is provided further downstream of the peeling roller (or peeling bar) 78c, and the base film BF2 on the release liner RL side is pulled away from the conveyance direction (downward in FIG. 4 ) via the peeling roller 78d. Thus, the base film BF2 is peeled from the optical film laminate F1 and taken up.

[0054] The optical film laminate F1 cut out from the web-like raw material laminate RM passes through the peeling roller 78d without changing the conveying direction and is sent out from the peeling device 78, and is taken out by a conveying device well known to those skilled in the art. In this manner, an optical film laminate F1 having one or more arbitrary shapes can be obtained.

[0055] Examples and comparative examples of the present invention are described below. Table 1 shows examples and comparative examples of the present invention. In the examples, an optical laminate was prepared in which a surface protective film was laminated on one side of a sheet-like optical functional film (optical functional layer) and a release liner was laminated on the other side, and sheet-like substrate films were laminated on both the surface protective film side and the release liner side. This was nipped with a laminating roller well known to those skilled in the art to form a raw material laminate with double-sided substrates, and static electricity was charged after nipping.

[0056] Next, the amount of static electricity on the surface of the charged double-sided substrate-attached raw laminate was measured, and the double-sided substrate-attached raw laminate was cut with a laser beam from the surface protective film side so as not to cut the substrate film on the release liner side. After cutting, the static electricity was removed, and the height of the protrusions at the end of the cut portion was measured for the optical film laminate obtained by peeling off the substrate films on both sides.

[0057] On the other hand, in Comparative Example 1, a sheet-like substrate film was laminated on the release liner side of the same optical laminate as in the Examples, and this was nipped with a lamination roller known to those skilled in the art to form a raw laminate with a single-sided substrate, which was then charged with static electricity. The raw laminate with a single-sided substrate was cut with laser light from the side opposite to the side on which the substrate film was laminated (the side on which the surface protective film was located), leaving the substrate film. After cutting, the static electricity was removed, and the height of the protrusions at the edge of the cut portion was measured for the optical film laminate obtained by peeling off the substrate film. In Comparative Example 2, the raw laminate with a double-sided substrate similar to that in the Examples was cut with laser light without being charged, and the height of the protrusions of the optical film laminate from which the substrate film had been removed was measured.

[0058] The optical laminate used was a mobile retarder polarizing film (GRT1794XH1UHC) manufactured by Nitto Denko Corporation, with a thickness of 178 μm. A 25 μm thick PET film was used as the substrate film. The electrostatic charging and de-electrification device used was a JPK-3 manufactured by Kasuga Electric Co., Ltd. The laser light used for cutting was a CO laser with a wavelength of 9.4 μm. ２ A TLSM301 manufactured by Takei Electric Co., Ltd. was used as a laser light generator, and the laser was focused on the surface of the polarizing film and cut at an output of 35 W, a frequency of 15 kHz, and a feed rate of 500 mm / sec.

[0059] The height of the raised portion was measured as follows. For each of the Examples and Comparative Examples, three optical film laminates were produced by the above method, and a laser microscope (manufactured by Keyence Corporation) was used to obtain a cross-sectional profile from an image of a portion of the edge of each cut portion of the optical film laminate. The amount of protrusion was measured at 50 locations from each cross-sectional profile, and the average value of the 50 protrusion amounts was calculated. For each of the Examples and Comparative Examples, the average values ​​of the protrusion amounts of the three optical film laminates calculated in this manner were further averaged, and this was defined as the height of the raised portion of the optical film laminate.

[0060]

[0061] In both Example 1 and Example 2, the amount of static electricity was −1.0 kV to −4.0 kV. However, in Example 1, charging was performed from the surface protection film side of the raw material laminate with double-sided substrates, while in Example 2, charging was performed from both sides of the raw material laminate with double-sided substrates. In both Examples, optical film laminates with substantially no protrusions were obtained.

[0062] In Example 3, the amount of static electricity was −11.0 kV to −12.0 kV, and charging occurred after nipping. When charging with such a small amount of static electricity (i.e., when the adhesion force due to static electricity is strong), although no protrusions were substantially generated on the contact surface, problems such as attraction of foreign matter, poor peeling due to incomplete neutralization, and adverse effects on peripheral devices due to atmospheric discharge may occur.

[0063] In Comparative Example 1, the amount of static electricity was -1.0 kV to -4.0 kV, which was similar to that in Examples 1 and 2. However, a 13 μm protrusion occurred at the cut portion on the surface protection film side where no substrate film was laminated. Therefore, an optical film laminate with substantially no protrusion at the cut portion was not obtained. As described above, Comparative Example 2 represents the result when a raw material laminate with double-sided substrates was cut with laser light without being charged, and slight charging occurred due to friction, etc. In Comparative Example 2, large protrusions were generated on both sides despite the presence of a substrate film.

[0064] F1 Optical film laminate without raised portion 11 One side 11a End 11b Edge 13 Other side 13a End 13b Edge 15 End face BF1, BF2 Base film BFR1, BFR2 Roll of base film RM Raw material laminate RMB Raw material laminate with double-sided base material RMR Remaining part of raw material laminate TP Peeling tape 40 Charging device 41 Laser light 42 Discharging device 60 Sheet-web type manufacturing device 61, 64, 69 Conveying device 62 Laminating device 62a Laminating roller 63 Charging device 65 Base 66 Laser cutting device 67 Discharging device 68 Peeling device 68a Pickup device 68b, 68c Peeling roller or peeling bar 70 Web-web type manufacturing device 72 Laminating device 72a Laminating roller 73 Charging device 74 Conveying device 75 Base 76 Laser cutting device 77 Discharge device 78 Peeling device 78a Bonding section 78b, 78c, 78d Peeling roller or peeling bar

Claims

1. A method for producing an optical film laminate, comprising the steps of: conveying a raw material laminate in which a first resin film is laminated on one side of an optical functional layer containing one or more films and a second resin film is laminated on the other side; laminating a first substrate on the first resin film of the raw material laminate and laminating a second substrate on the second resin film to obtain a raw material laminate with double-sided substrates; charging the raw material laminate, the first substrate, the second substrate, or the raw material laminate with double-sided substrates, or a plurality of these, with static electricity to bring the first substrate and the second substrate into close contact with the raw material laminate; forming a cut surface of an arbitrary shape in the raw material laminate using a laser beam; removing static electricity from the raw material laminate with double-sided substrates; and peeling off the first substrate and the second substrate from one or more optical film laminates having the cut surfaces of an arbitrary shape.

2. The manufacturing method described in claim 1, wherein the bonding step comprises charging both sides of the raw material laminate, both the first substrate and the second substrate, or both sides of the raw material laminate with double-sided substrates, or a combination of these with static electricity.

3. The manufacturing method according to claim 1, wherein one of the first resin film and the second resin film is a surface protection film, and the other of the first resin film and the second resin film is a release liner.

4. The manufacturing method according to claim 1, wherein the raw material laminate is a web-like laminate.

5. The manufacturing method according to claim 1, wherein the first substrate and the second substrate are web-like substrates.

6. The manufacturing method according to claim 1, wherein the first substrate and the second substrate are non-adhesive substrates.

7. The manufacturing method according to claim 1, wherein the first substrate and the second substrate are made of the same material.

8. The manufacturing method described in claim 1, wherein the amount of static electricity applied is an amount that does not cause the first substrate and the second substrate to peel off from the raw material laminate when the cut surface is formed by the laser light.

9. The manufacturing method according to claim 8, wherein the amount of static electricity is −10 kV or more and −0.5 kV or less, or 0.5 kV or more and 10 kV or less.

10. The manufacturing method according to claim 9, wherein the amount of static electricity is −4.0 kV or more and −0.5 kV or less.

11. The manufacturing method according to claim 1, wherein in the step of obtaining the raw material laminate with substrates on both sides, the first substrate or the second substrate, or both, are reused substrates that have been peeled off in the step of peeling off one or more of the optical film laminates having the cut surfaces of any shape from the first substrate and the second substrate.

12. An apparatus comprising: a conveying device that conveys a raw material laminate in which a first resin film is laminated on one side of an optical functional layer containing one or more films and a second resin film is laminated on the other side; a lamination device that laminates a first substrate on the first resin film of the raw material laminate and a second substrate on the second resin film to produce a raw material laminate with double-sided substrates; a charging device that charges the raw material laminate, the first substrate, the second substrate, or the raw material laminate with double-sided substrates, or a plurality of these, with static electricity in order to adhere the first substrate and the second substrate to the raw material laminate; a laser cutting device that cuts the raw material laminate of the raw material laminate with double-sided substrates to form one or more optical film laminates of any shape; a static elimination device that removes static electricity from the raw material laminate with double-sided substrates; and a peeling device that peels off the first substrate and the second substrate from the one or more optical film laminates of any shape.

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