Film laminate and method for producing film member

Abstract

A film laminate (1) is configured by sequentially stacking a film member (11), a protective film (21), an adhesive part (31), and a heat shrinkable film (41) in this order. The adhesive part (31) is disposed in accordance with the tendency of warp of the film member (11). In the case when the film member (11) is warped, the film laminate (1) is heated and the protective film (21) is separated from the film member (11), thereby obtaining the film member (11) in which warping is corrected.

Description

Film laminate and method for manufacturing film member

[0001] The present disclosure relates to a film laminate and a method for manufacturing a film member.

[0002] Conventionally, the screens of various display devices, such as liquid crystal display devices and organic electroluminescence (EL) display devices, are composed of a laminated structure including a film member. Examples of such film members include a touch panel (TP), a polarizing plate (POL), a metal layer, a protective film, and a laminated film thereof. Such laminated structures are automatically manufactured by a manufacturing device that handles various film members. Examples of components for handling the film member in such a manufacturing device include a suction stage that suctions and places the film member on a stage, and a film chuck that grips a pair of opposing edges of the film member from both sides.

[0003] Film members may warp depending on manufacturing conditions or the environment. For example, touch panels or polarizing plates have a structure in which multiple films or a film and a metal layer are stacked. Therefore, these film members are prone to warping due to differences in the shrinkage of the layers that make up the film member, depending on conditions such as temperature and humidity.

[0004] 15, when the film member 100 is warped, the center of the film member 100 comes into contact with the suction stage 110 and is adsorbed. On the other hand, the edge of the film member 100 is not adsorbed because it is floating above the suction stage 110. Therefore, the suction force that fixes the film member 100 on the suction stage 110 is weak, and the film member 100 is likely to become misaligned.

[0005] 16 , if the film member is warped, the center and edge portions of the film member 100 will be misaligned in the thickness direction, and the film chuck 120 will not abut against the edge portion at a predetermined position. As a result, the film chuck 120 may not be able to grip the film member 100. Alternatively, the film member 100 gripped by the film chuck 120 may easily become misaligned, causing the film member 100 to fall off the film chuck 120.

[0006] Therefore, if the film member is warped, problems such as suction errors or chucking errors are likely to occur in the film member transport system in the automatic manufacturing device for the above-mentioned laminated structure.

[0007] As a countermeasure to such manufacturing problems, techniques for preventing warping of film members have been studied. One known technique involves temporarily attaching a film member to an auxiliary film that is larger than the film member prone to warping, and then handling the film member by handling the auxiliary film in this state (see, for example, Patent Document 1).

[0008] Japanese Patent Application Publication No. 2006-155452

[0009] However, the above-mentioned conventional technology requires equipment or a device capable of handling a large auxiliary film relative to the film material. Furthermore, the auxiliary film ultimately needs to be peeled off from the film member. Therefore, the laminated structure manufacturing device for handling the film member must be configured to be able to handle an auxiliary film larger than the film member. Therefore, it may not be applicable to existing automated manufacturing devices that handle film members.

[0010] An object of one aspect of the present disclosure is to provide a technology that enables a film member to be used simply and independently without warping.

[0011] In order to solve the above-mentioned problems, a film laminate according to one embodiment of the present disclosure comprises a film member having a tendency to warp, a heat-shrinkable film having heat-shrinkability and superimposed on the surface side of the film member that protrudes when the film member warps, and an adhesive portion interposed between the film member and the heat-shrinkable film for adhering the film member and the heat-shrinkable film, the adhesive portion being arranged at at least both ends of the film member in a second direction that intersects a first direction in which the peak of the warp of the film member extends.

[0012] In addition, in order to solve the above-mentioned problems, a method for manufacturing a film member according to one embodiment of the present disclosure includes the steps of: obtaining a film laminate by adhering a heat-shrinkable film to a film member having a tendency to warp at at least both ends in a second direction intersecting a first direction in which the apex of the warp extends; detecting the warp of the film member; heating the film laminate in which the warp of the film member has been detected to heat-shrink the heat-shrinkable film; and peeling off the heat-shrinkable film from the film member.

[0013] According to one aspect of the present disclosure, the film member can be used alone and without warping when in use.

[0014] FIG. 1 is a diagram schematically illustrating a configuration of a film laminate according to a first embodiment of the present disclosure. FIG. 2 is a diagram for explaining indications related to warpage of a film member. FIG. 3 is a diagram schematically illustrating a configuration of a film laminate according to a second embodiment of the present disclosure. FIG. 4 is a diagram illustrating the tendency of warpage of a film member in one aspect of a film laminate according to a third embodiment of the present disclosure. FIG. 5 is a diagram illustrating an example of an arrangement of adhesive portions in one aspect of a film laminate according to the third embodiment of the present disclosure. FIG. 6 is a diagram illustrating the tendency of warpage of a film member in another aspect of a film laminate according to the third embodiment of the present disclosure. FIG. 7 is a diagram illustrating an example of an arrangement of adhesive portions in another aspect of a film laminate according to the third embodiment of the present disclosure. FIG. 8 is a diagram illustrating the tendency of warpage of a film member in a film laminate according to a fourth embodiment of the present disclosure. FIG. 9 is a diagram illustrating an example of an arrangement of adhesive portions in a film laminate according to the fourth embodiment of the present disclosure. FIG. 10 is a diagram illustrating another example of an arrangement of adhesive portions in a film laminate according to the fourth embodiment of the present disclosure. FIG. 11 is a diagram illustrating a first example of an arrangement of adhesive portions in a film laminate according to an embodiment of the present disclosure. FIG. 12 is a diagram illustrating a second example of an arrangement of adhesive portions in a film laminate according to an embodiment of the present disclosure. FIG. 13 is a diagram illustrating a third example of an arrangement of adhesive portions in a film laminate according to an embodiment of the present disclosure. 10A and 10B are diagrams illustrating a state in which a warped film member is sucked onto a suction stage and a state in which a warped film member is gripped by a film chuck;

[0015] [Embodiment 1] As shown in Figure 1, a film laminate 1 according to embodiment 1 of the present disclosure includes a film member 11, a protective film 21, an adhesive portion 31, and a heat-shrinkable film 41, which are stacked in the above order.

[0016] [Film Member] The film member 11 is a film-like member. The film member 11 may be a single-layer film-like member, or may be a member in which multiple film-like members are laminated. Examples of the film member 11 include a touch panel, a TAC film, and a polyimide film. The shape of the film member 11 when viewed from above (hereinafter simply referred to as "planar shape") is not limited. Examples of the planar shape of the film member 11 include a rectangle, a circle, and an irregular shape.

[0017] The film member 11 has a tendency to warp. For example, as shown in FIGS. 1 and 2, the film member 11 has a tendency to warp in the longitudinal direction of the rectangle. The direction in which the film member 11 warps may be only one direction, or two mutually perpendicular directions, or may be any other direction. The warp direction of the film member 11 is determined by the type of resin of the laminated film that constitutes the film member 11, the manufacturing method of the film (stretching, etc.), or the environment (temperature and humidity). The film member 11 only needs to have a tendency to warp, and may or may not actually warp.

[0018] 1 and 2, arrow A1 represents the direction in which the apex of the warp in the film member 11 extends (also referred to as the "first direction"). Arrow A2 represents the direction (also referred to as the "second direction") that intersects (orthogonal in this embodiment) with the direction indicated by arrow A1. Arrow A3 represents the warp in the warp tendency of the film member 11. Arrow A4 represents the warp when the film member 11 actually warps. In this embodiment, arrows A3 and A4 indicate that the film member 11 warps in the longitudinal direction toward the heat-shrinkable film 41 and protrudes toward the heat-shrinkable film 41.

[0019] [Protective Film] The protective film 21 is superimposed on the surface of the film member 11 on the side that protrudes when the film member 11 warps. The protective film 21 is a film that can be adhered to and peeled off from the film member 11, and is, for example, a film that directly adheres to the surface of the film member 11. The protective film 21 may be interposed between the film member 11 and a heat-shrinkable film 41 described below. For example, the protective film 21 may be a film that overlaps the entire surface of the film member 11, or a film that overlaps only the portion of the surface of the film member 11 that comes into contact with the heat-shrinkable film 41. It is preferable that the film laminate 1 has the protective film 21 from the viewpoint of easily obtaining the film member 11 from the film laminate 1, and from this viewpoint, it is more preferable that the protective film 21 be a film that overlaps the entire surface of the film member 11.

[0020] The material of the protective film 21 may be appropriately determined in accordance with the surface material of the film member 11 to be adhered, as long as it is peelable. Examples of materials for the protective film 21 include PET (polyethylene terephthalate).

[0021] Alternatively, the protective film 21 may have an adhesive layer that can be peeled off from the surface of the film member 11, and may be adhered to the film member 11 via the adhesive layer. The adhesive layer may be capable of adhering the film member 11 and the protective film 21 together so that the protective film 21 can be attached and detached from the surface of the film member 11 with sufficient strength. The adhesive layer may be disposed over the entire area where the film member 11 and the protective film 21 are adhered, or may be disposed so as to be arranged intermittently in the adhesive area, such as in a dotted or linear pattern. Examples of materials for the adhesive layer include acrylic adhesives.

[0022] [Heat-Shrinkable Film] The heat-shrinkable film 41 has heat-shrinkability. The heat-shrinkable film 41 may have heat-shrinkability such that it shrinks more than the film member 11 when heated. The heat-shrinkable film 41 may be selected from known heat-shrinkable resin films depending on the type and thermal properties of the film member 11. For example, when the film member 11 is a touch panel or polarizing plate in a display device, the protrusion height of the top (the center in the longitudinal direction) of the film member 11 when warped relative to a dimension of 180 mm in the longitudinal direction (direction of arrow A2) is approximately 3 to 5 mm. This protrusion height is the distance between the edge and the center of the film member 11 in the thickness direction of the film member 11. In this case, the heat-shrinkable film 41 is preferably a film that exhibits a heat shrinkage rate of 2 to 7% relative to its dimension at room temperature (20 to 28°C), from the viewpoint of correcting warpage of the film member 11 caused by the heat-shrinkable film 41. Examples of resin materials for the heat-shrinkable film 41 include polystyrene, polyvinyl chloride, and polyolefin.

[0023] The heat-shrinkable film 41 is overlaid on the surface of the film member 11 that protrudes when the film member 11 is stretched along the film member 11. The heat-shrinkable film 41 pulls the warp of the film member 11 in a direction in which both ends of the warp on the surface of the heat-shrinkable film 41 (both ends in the direction indicated by arrow A2 in the case of the film member 11) approach each other from the side that protrudes when the film member 11 warps due to thermal shrinkage caused by heating. The planar shape of the heat-shrinkable film 41 may be substantially the same as the planar shape of the film member 11. Alternatively, the planar shape of the heat-shrinkable film 41 may be a tape-like film having substantially the same length as the dimension of the film member 11 in the longitudinal direction (direction indicated by arrow A2), which is the warping direction.

[0024] [Adhesive portion] The adhesive portion 31 is interposed between the film member 11 and the heat-shrinkable film 41 to bond them together. In the film laminate 1, the protective film 21 is in close contact with the film member 11. Therefore, the adhesive portion 31 is disposed on the surface of the protective film 21 and directly bonds the protective film 21 and the heat-shrinkable film 41 together, thereby indirectly bonding the film member 11 and the heat-shrinkable film 41 together.

[0025] The adhesive portions 31 are arranged along the short side of each edge (longitudinal end) of the film member 11. In this way, the adhesive portions 31 are arranged at least at both ends of the film member 11 in the direction of arrow A2, which intersects with the direction of arrow A1 in which the peak of the warp of the film member 11 extends. More specifically, in the film laminate 1, the adhesive portions 31 extend along the short side (direction indicated by arrow A1) at both ends of the film member 11 in the longitudinal direction (direction indicated by arrow A2). The arrangement of the adhesive portions 31 when viewed in a plan view will be described further below.

[0026] The adhesive portion 31 can be formed by applying a known adhesive capable of bonding the resin films to be bonded (protective film 21 and heat-shrinkable film 41 in the case of the film laminate 1) to appropriate locations on the protective film 21 or the heat-shrinkable film 41. Examples of such adhesives include various adhesives such as acrylic, silicone, and urethane adhesives.

[0027] The protective film 21 may be omitted if the adhesive portion 31 is peelable from the film member 11. In this case, the adhesive portion 31 is interposed between the film member 11 and the heat-shrinkable film 41 and directly bonds the film member 11 to the heat-shrinkable film 41. In this case, it is preferable that the adhesive portion 31 be capable of peelably adhering the film member 11 and have stronger adhesion to the heat-shrinkable film 41 than to the film member 11, from the viewpoint of easily obtaining the film member 11 from the film laminate 1.

[0028] [Method for manufacturing film laminate] A protective film 21 having the same planar shape (dimensions) as the film member 11 is attached to a film member 11 such as a touch panel or a polarizing plate. The protective film 21 is attached to one of the surfaces of the film member 11 that protrudes when warping occurs. The attachment of the protective film 21 may be by simple pressure bonding, by attachment with an adhesive, or by fusion bonding such as thermocompression bonding, as long as the protective film 21 can be subsequently peeled off from the film member 11.

[0029] Next, adhesive portions 31 are formed on the surface of the protective film 21 at positions that correspond to the tendency of warping of the film member 11. The adhesive portions 31 are formed, for example, by applying an adhesive to appropriate positions on the surface of the protective film 21.

[0030] Next, a heat-shrinkable film 41 having the same planar shape (dimensions) as the protective film 21 and the film member 11 is placed on the protective film 21 via the adhesive portion 31, and, for example, a portion of the heat-shrinkable film 41 corresponding to the adhesive portion 31 is appropriately pressed. In this way, the heat-shrinkable film 41 is adhered to the protective film 21, and as a result, the film laminate 1 is produced.

[0031] [Uses of Film Laminate] The film laminate 1 can be used to correct warpage of a film member 11. Film members containing functional resin films, such as touch panels or polarizing plates, may expand, contract, or absorb moisture due to temperature or humidity, resulting in warpage. Therefore, even if the film member 11 is not warped immediately after the production of the film laminate 1, it may warp during storage until it is used in the next process.

[0032] When warping occurs in the film member 11, the entire film laminate 1 warps in accordance with the tendency of warping of the film member 11. In this case, the film laminate 1 is heated (for example, at 60° C. for about 15 minutes) to cause the heat-shrinkable film 41 to shrink.

[0033] In the film laminate 1, the adhesive portion 31 fixes the film member 11 (and the protective film 21) to the heat-shrinkable film 41 along the entire edge of the short side of the film member 11. Therefore, the heat-shrinkable film 41 does not shrink in its short direction (the direction indicated by the arrow A1), and the film member 11 does not deform in that direction.

[0034] In contrast, in the longitudinal direction (direction indicated by arrow A2) of heat-shrinkable film 41, both ends thereof are fixed by adhesive portions 31, while the remaining portion, which is the majority of the film, is not fixed and can be heat-shrinked. Therefore, heat-shrinkable film 41 shrinks in the longitudinal direction (direction indicated by arrow A2).

[0035] The heat-shrinkable film 41 is disposed on the surface of the film member 11 that protrudes when warping occurs. Therefore, the film member 11 deforms in a direction in which both longitudinal ends are drawn together due to the longitudinal contraction of the heat-shrinkable film 41. As a result, the surface of the film member 11 that protrudes when warping occurs deforms in a direction in which it contracts, and the warping of the film member 11 (film laminate 1) is eliminated. In this way, the warping of the film member 11 is corrected by heating.

[0036] In this state, the protective film 21 is peeled off from the film member 11 to obtain the film member 11 with the warp corrected. A method for obtaining such a film member will be described later.

[0037] [Interim Summary] As described above, in the film laminate 1, the heat-shrinkable film 41 is overlaid on the surface of the film member 11 that protrudes when the film member 11 is stretched along the film laminate 1. Furthermore, the adhesive portions 31 are disposed at least on both ends of the film member 11 in the direction of arrow A2, which intersects with the direction of arrow A1 along which the apex of the warp of the film member 11 extends. Therefore, the film laminate 1 allows the film member 11 to be used alone and without warping.

[0038] Furthermore, in the film laminate 1, the adhesive portions 31 extend along the short side (direction indicated by arrow A1) at both ends of the longitudinal direction (direction indicated by arrow A2) of the film member 11. Therefore, the heat-shrinkable film 41 shrinks only in the direction that eliminates warping of the film member 11, which is even more effective in uniformly correcting warping of the film member 11.

[0039] Furthermore, the adhesive portion 31 is disposed on the surface of the protective film 21 and bonds the protective film 21 to the heat-shrinkable film 41. This is even more effective from the viewpoint of easily obtaining the film member 11 whose warpage has been corrected from the film laminate 1.

[0040] Other embodiments of the present disclosure will be described below. For convenience of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above-described embodiments, and the description thereof will not be repeated.

[0041] [Embodiment 2] Fig. 3 is a diagram schematically illustrating the configuration of a film laminate according to a second embodiment of the present disclosure. The film laminate 2 has the same configuration as the above-described film laminate 1, except that it has a film member 12 instead of the film member 11 and an adhesive portion 32 instead of the adhesive portion 31. Note that in Fig. 3, the film member 12 and the protective film 21 are depicted as an integrated film-like configuration.

[0042] The film member 12 is the same as the film member 11 except that it has a tendency to warp in the short-side direction. That is, when the film member 12 warps, the peak of the warp extends along the longitudinal direction (arrow A1). The adhesive portions 32 are arranged along the longitudinal direction on each of the longitudinal edge portions of the film member 12. In this manner, the adhesive portions 32 are arranged at least on both ends of the film member 12 in the direction of arrow A2, which intersects with the direction of arrow A1 along which the peak of the warp of the film member 12 extends. The adhesive portions 32 extend along the longitudinal direction (direction indicated by arrow A1) at both ends of the film member 12 in the short-side direction (direction indicated by arrow A2).

[0043] As described above, the direction of warping of the film member 12 is largely determined by the type (touch panel, polarizing plate, etc.) or size of the film member 12. Therefore, the arrangement of the adhesive portions 32 is determined depending on the warping that occurs in the film member 12. In this embodiment, too, the adhesive portions 32 extend along a direction in which warping does not need to be corrected, and the adhesive portions 32 are arranged only at both ends in the direction in which warping needs to be corrected. In this way, the heat-shrinkable film 41 shrinks in the direction in which warping needs to be corrected, and the shrinkage direction (the direction of correction) is controlled.

[0044] In the film laminate 2, like the film laminate 1, the heat-shrinkable film 41 shrinks only in the direction that eliminates the warp of the film member 12, which is even more effective from the viewpoint of uniformly correcting the warp of the film member 12.

[0045] [Embodiment 3] Fig. 4 is a diagram showing the tendency of warping of a film member in one aspect of a film laminate according to a third embodiment of the present disclosure. As shown in Fig. 4, the film member 13 has a tendency to warp along one diagonal line of the rectangular planar shape (in the direction indicated by arrow A2). Therefore, when the film member 13 warps, the apex of the warp of the film member 13 extends in the direction indicated by arrow A1.

[0046] An example of the arrangement of adhesive portions in a film laminate having the above-described film member 13 is shown in Fig. 5. As shown in Fig. 5, the adhesive portions are formed by adhesive portions 33a arranged on one diagonal line in the planar shape (rectangle) of the film member 13 along arrow A1, and adhesive portions 33b arranged at both ends of the other diagonal line indicated by arrow A2. Thus, in the above embodiment, the adhesive portions include portions (adhesive portions 33a) that follow the peaks of the warps of the film member 13.

[0047] In this manner, in the above embodiment, adhesive portions 33b are formed at both ends of the planar shape of film member 13 in the warping direction (the direction indicated by arrow A2), and adhesive portions 33a are formed along the entire length of the diagonal line intersecting the warping direction. Therefore, adhesive portions 33a corresponding to the peaks of the warping secure both film member 13 and the heat-shrinkable film, so that the heat-shrinkable film does not shrink when heated, and film member 13 does not deform in the direction along adhesive portions 33a. Meanwhile, in the direction indicated by arrow A2, adhesive portions 33b are formed only at both ends of the diagonal line, so that the heat-shrinkable film between adhesive portions 33b shrinks when heated, thereby eliminating the warping of film member 13.

[0048] In the embodiment of the present disclosure, the planar shape of the film member is not limited to a rectangle. Figure 6 shows the tendency of warping of the film member in another aspect of the film laminate according to this embodiment. As shown in Figure 6, the planar shape of the film member 14 is circular. The film member 14 has a tendency to warp in the direction indicated by arrow A2. Therefore, when the film member 14 warps, the apex of the warp extends in the direction of arrow A1, which is perpendicular to arrow A2.

[0049] 7 is a diagram showing an example of the arrangement of the adhesive portions in the above embodiment. As shown in FIG. 7, the adhesive portions include adhesive portions 34a extending along the diameter in the direction indicated by arrow A1 and adhesive portions 34b arranged at both ends of the diameter in the direction indicated by arrow A2. Thus, in the above embodiment, the adhesive portions also include portions (adhesive portions 34a) that extend along the peaks of the warp of the film member.

[0050] In the above embodiment, adhesive portions 34b are formed at both ends in the warping direction (the direction indicated by arrow A2) in the planar shape of film member 14, and adhesive portion 34a is formed along the entire diameter in the warping direction. Therefore, film member 14 does not deform at the peak of the warp, and the heat-shrinkable film portion between adhesive portions 34b at both ends in the direction of arrow A2 shrinks when heated, resulting in the warping of film member 14 being eliminated.

[0051] In this way, even if the planar shape is an irregular shape other than a rectangle, such as a circle, it is possible to correct the warping of the film member by appropriately arranging the adhesive portions according to the tendency of the film member to warp.

[0052] In this embodiment, both of the adhesive portions 33b and 34b have a rectangular planar shape, but the planar shape of these adhesive portions is not limited to a rectangle and may be any shape. The planar shapes of the pair of adhesive portions may be the same or different.

[0053] [Embodiment 4] In this embodiment, a case where a film member has a tendency to warp in two directions is described. FIG. 8 is a diagram showing the tendency of warping of a film member in a film laminate according to a fourth embodiment of the present disclosure. As shown in FIG. 8, the film member 15 has a rectangular planar shape and has a tendency to warp in both the short-side direction and the long-side direction. That is, the film member 15 has a tendency to warp in both the short-side direction indicated by arrow A12 and the long-side direction indicated by arrow A21. Therefore, when the film member 15 warps, the central portion of the planar shape particularly protrudes. Furthermore, the peak of the warp extends along both the short-side direction and the long-side direction that intersect the central portion.

[0054] The tendency of warpage in the lateral direction is indicated by arrow A32. The peak of this warpage extends in the direction indicated by arrow A21, and the direction intersecting this direction is indicated by arrow A12. The tendency of warpage in the longitudinal direction is indicated by arrow A31. The peak of this warpage extends in the direction indicated by arrow A12, and the direction intersecting this direction is indicated by arrow A21.

[0055] An example of the arrangement of adhesive portions corresponding to the film member 15 is shown in FIG. 9 . As shown in FIG. 9 , adhesive portions 35 a are arranged at each of the four corners of the rectangular planar shape of the film member 15. When the direction in which the peaks of the warp extend is the short-side direction (the direction indicated by arrow A12), adhesive portions 35 a may be arranged at both ends in the direction indicated by arrow A21. When the direction in which the peaks of the warp extend is the long-side direction (the direction indicated by arrow A21), adhesive portions 35 a may be arranged at both ends in the direction indicated by arrow A12. In this way, adhesive portions 35 a are arranged at both ends of the film member 15 in a second direction (the direction indicated by arrow A21 and the direction indicated by arrow A12) that intersects with the two first directions (the direction indicated by arrow A12 and the direction indicated by arrow A21) in which the peaks of the warp of the film member 15 extend.

[0056] The adhesive portions 35a secure both the film member 15 and the heat-shrinkable film at the four corners of the rectangle. Therefore, when the heat-shrinkable film is heated, the film member 15 deforms so that it shrinks in both the short-side direction and the long-side direction due to the shrinkage of the heat-shrinkable film. As a result, both the warp in the short-side direction indicated by arrow A32 and the warp in the long-side direction indicated by arrow A31 are eliminated.

[0057] Alternatively, the adhesive portions 35b may be arranged on the film member 15 as shown in FIG. 10 . FIG. 10 is a diagram showing another example of the arrangement of adhesive portions on the film member 15. As shown in FIG. 10 , the adhesive portions 35b are formed on two diagonal lines of the planar shape (rectangle) of the film member 15. Thus, the adhesive portions 35b have an X-shaped planar shape. The diagonal portions of the adhesive portions 35b extend in directions that intersect both the first directions (the directions indicated by arrows A12 and A21) of each warp tendency and intersect at the center of the rectangle of the film member 15. In this way, the adhesive portions 35b intersect without overlapping or following the first directions (the directions indicated by arrows A12 and A21) of the two warps. Furthermore, the adhesive portions 35b extend in two directions that intersect at the portion where the peaks of the two warps overlap (the center of the rectangle).

[0058] The adhesive portion 35b divides the rectangular planar shape of the film member 15 into four triangular regions separated by two diagonal lines. The adhesive portion 35b secures both the film member 15 and the heat-shrinkable film along the two diagonal lines. When heated, the heat-shrinkable film shrinks more in the short and long directions of the planar shape of the film member 15, the closer it is to each side of the planar shape. As a result, the film member 15 deforms in a shrinking direction. As a result, both the warp in the short direction indicated by arrow A32 and the warp in the long direction indicated by arrow A31 are eliminated.

[0059] In this manner, the present embodiment provides adhesive portions 35a arranged at both ends in a second direction intersecting with a first direction in which the peaks of the warps extend, or adhesive portions 35b arranged over the entire second direction, for a film member 15 that has a tendency to warp in each of two intersecting directions. Therefore, it is possible to eliminate warping of a film member 15 that has warped in each of two intersecting directions.

[0060] [Embodiment 5] In the present disclosure, the amount of deformation of the film member that corrects warpage can be adjusted by adjusting the spacing of the adhesive portions. For example, as shown in Fig. 11, the adhesive portions include adhesive portions 36a that are arranged along the short sides of the film member having a rectangular planar shape, and adhesive portions 36b that are arranged intermittently along the long sides of the film member.

[0061] In the film laminate having the adhesive portions 36 a and 36 b as shown in Fig. 11, none of the short sides of the film members deforms in the lateral direction when heated. Therefore, even if the film laminate is heated, the film members do not deform in the lateral direction.

[0062] On the other hand, in this film laminate, adhesive portions 36b are intermittently arranged along the long sides in the longitudinal direction. Although each adhesive portion 36b does not shrink when heated, the heat-shrinkable film shrinks in the portions between the adhesive portions 36b in the longitudinal direction of the film member, causing the film member to deform and shrink along the longitudinal direction. Therefore, the adhesive portion arrangement shown in FIG. 11 is effective when it is desired to shrink the film member only in the longitudinal direction by a small amount.

[0063] The amount of shrinkage of the film member can be adjusted by the size and spacing of the adhesive joints, and by making the size of the adhesive joints smaller or by increasing the spacing between the adhesive joints, the amount of deformation of the film member due to heating can be increased. The adhesive joint arrangement shown in Figure 11 is effective in eliminating warping of film members that tend to warp slightly.

[0064] The adhesive portions may also be arranged as shown in Fig. 12. As shown in Fig. 12, adhesive portions 37 are arranged intermittently along each of the two long sides of a film member having a rectangular planar shape.

[0065] In the adhesive arrangement shown in Figure 12, when the film laminate is heated, the heat-shrinkable film shrinks significantly in the short direction and to a lesser extent in the long direction. Therefore, the film member also deforms, shrinking significantly in the short direction and shrinking less in the long direction. The adhesive arrangement shown in Figure 12 is effective in eliminating warping of the film member, which tends to warp in two directions, but by different magnitudes.

[0066] Furthermore, the adhesive portions may be arranged as shown in Fig. 13. As shown in Fig. 13, the adhesive portions include an L-shaped adhesive portion 38a arranged along one pair of adjacent short sides and long sides of the film member having a rectangular planar shape, and an adhesive portion 38b arranged at a corner between another pair of adjacent short sides and long sides.

[0067] In the adhesive arrangement shown in Fig. 13, when the film laminate is heated, the heat-shrinkable film does not shrink along one pair of adjacent short sides and long sides, and the film member does not deform. On the other hand, the heat-shrinkable film shrinks along the other pair of adjacent short sides and long sides, and the film member deforms in a shrinking direction. The adhesive arrangement shown in Fig. 13 is effective in eliminating warping of a film member that has a tendency to warp relatively only at one corner of a rectangle.

[0068] In the above-described embodiment, the adhesive portions are arranged in a straight line, but the adhesive portions in the present disclosure may be arranged in a curved line or in a curved line (e.g., a zigzag shape) depending on the tendency of the film member to warp.

[0069] [Embodiment 8] As described above, the film laminate according to the present disclosure has a configuration in which one or two films are superimposed and fixed to a film member, and warping of the film member can be eliminated depending on the arrangement of the adhesive joints. Therefore, when the film member warps during use, the film laminate can be suitably used to obtain a film member from which warping has been eliminated.

[0070] FIG. 14 is a flow diagram showing the flow of steps in a method for producing a film member according to an embodiment of the present disclosure.

[0071] First, a heat-shrinkable film is bonded to a film member via adhesive at least both ends in a second direction intersecting a first direction in which the apex of the warp of the film member extends. For example, a heat-shrinkable film such as a polystyrene (PS) resin film or a polyvinyl chloride (PVC) resin film is newly attached to a film member such as a touch panel that has a tendency to warp to form a film laminate. The heat-shrinkable film is attached to the film member at a portion (adhesive portion) formed, for example, with a weak adhesive material. In this way, a film laminate is obtained.

[0072] In a film laminate, the film member is usually not warped immediately after production, but the film member may deform and warp over time depending on the conditions such as temperature and humidity in the environment in which the film laminate is stored.

[0073] In step S11, it is detected whether the film member is warped. Warping of the film member can be detected as warping of the film laminate. Therefore, in step S11, warping of the film laminate may be detected as warping of the film member. Warping of the film laminate may be confirmed visually, or the degree of lift (height) of a portion of an edge of the film laminate relative to a reference plane may be measured when the remaining portion of the edge is pressed, and the presence or absence of warping may be determined based on a threshold value of the height.

[0074] The film laminate in which warpage of the film member is detected in step S11 is subjected to a heat treatment in step S12. The heat treatment is a treatment in which the film laminate is heated to a temperature at which the heat-shrinkable film thermally shrinks. The heating temperature can be appropriately determined within a range at which the heat-shrinkable film is sufficiently thermally shrunk and the film member is not substantially denatured by heat.

[0075] If the film member is warped, the heat-shrinkable film shrinks by heating, and the shrinking force corrects the warp of the film member. The heat-shrinkable film at the adhesive joint is less likely to shrink or change. Therefore, as mentioned above, it is possible to control the direction of warp correction by changing the size or arrangement of the adhesive joint.

[0076] In step S12, the conditions of the heat treatment can be changed depending on the amount of warpage of the film laminate, thereby changing the force for correcting the warpage. For example, by appropriately adjusting the heating time or heating temperature to appropriately adjust the amount of thermal shrinkage of the heat-shrinkable film, it is possible to correct warpage from slight to severe. This heat treatment causes the film members in the film laminate to deform in a shrinking direction as the heat-shrinkable film thermally shrinks, thereby eliminating the warpage of the film members.

[0077] Next, in step S13, the heat-shrinkable film is peeled off from the film laminate. If the film member is not warped, the heat-shrinkable film is peeled off in this step without performing the heat treatment in step S12. That is, in step S13, the heat-shrinkable film is peeled off from a film laminate in which the warping of the film member has been eliminated in step S12, or from a film laminate in which no warping was detected in step S11. For example, in the case of a film laminate having a layer structure as shown in FIG. 1, only the film member is removed by peeling the protective film from the film member. Note that if the film laminate does not have a protective film, only the film member is removed by peeling the heat-shrinkable film together with the adhesive portion from the film member. For film laminates that are not warped, the heat treatment step is omitted, and only the heat-shrinkable film is peeled off. The effects of the heat treatment in the production of film members are minimized.

[0078] In the method for manufacturing a film member according to this embodiment, a heat-shrinkable film may be applied only to the film member in which warpage is detected, and the warpage of the film member may be corrected by heat treatment. In this embodiment, the step of obtaining a film laminate may be carried out after the step of detecting warpage of the film member. In this embodiment, it is possible to confirm the actual warpage of the film member and appropriately determine the placement of the adhesive depending on the direction in which warpage is to be corrected, etc.

[0079] [Uses of Film Member] According to this embodiment, a film member without warping can be obtained by peeling the heat-shrinkable film from a film laminate that has been subjected to heat treatment as needed. Therefore, the film member can be applied as a material to manufacturing equipment including suction plates or chucks, and can be suitably used as a film-shaped material for various products including automatically manufactured laminated structures.

[0080] [Others] According to the various aspects of the present disclosure described above, the film member can be used alone and without warping. The present disclosure, which has such effects, is expected to contribute to improving the productivity of various products that use the film member as part of their materials. Therefore, the present disclosure is expected to contribute to achieving, for example, Goal 9 of the United Nations' Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization, and build resilient infrastructure."

[0081] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0082] 1 Film laminate 11, 12, 13, 14, 15 Film member 21 Protective film 31, 32, 33a, 33b, 34a, 34b, 35a, 35b, 36a, 36b, 37, 38a, 38b Adhesive portion 41 Heat-shrinkable film A1 Arrow indicating the direction in which the peak of warp in the film member extends A2 Arrow indicating a second direction intersecting with arrow A1 A3 Arrow indicating the warp in the warp tendency of the film member A4 Arrow indicating the warp when the film member is actually warped A12 Arrow indicating the direction in which the peak of the first warp in the film member extends (intersecting with the direction in which the peak of the second warp extends) A21 Arrow indicating the direction in which the peak of the second warp in the film member extends (intersecting with the direction in which the peak of the first warp extends) A31 Arrow A32 showing the direction of the tendency of the film member to warp due to the first warp. Arrow A33 showing the direction of the tendency of the film member to warp due to the second warp.

Claims

1. A film laminate comprising: a film member having a tendency to warp; a heat-shrinkable film having heat shrinkability and overlaid on the surface side of the film member that protrudes when the film member warps; and an adhesive portion interposed between the film member and the heat-shrinkable film for adhering the film member and the heat-shrinkable film, the adhesive portion being disposed at least at both ends of the film member in a second direction that intersects with a first direction in which the peak of the warp of the film member extends.

2. The film laminate of claim 1, wherein said adhesive is further disposed along said top portion.

3. The film laminate according to claim 1, wherein the adhesive portion extends along the first direction at both ends of the film member in the second direction.

4. The film laminate according to claim 1, wherein the film member has a tendency to warp in each of two mutually intersecting directions, the adhesive portion extends in the two directions so as not to overlap the first direction in each warp, and the adhesive portion extending in the two directions intersects at the portion where the apexes of each warp overlap.

5. A film laminate according to any one of claims 1 to 4, wherein the adhesive portions are arranged discontinuously in the extending direction.

6. A film laminate according to any one of claims 1 to 5, further comprising a protective film that is overlaid on the surface of the film member that protrudes when the film member warps and is capable of adhering to and peeling from the film member, and the adhesive portion bonds the protective film and the heat-shrinkable film.

7. A method for manufacturing a film member, comprising: a step of obtaining a film laminate by adhering a heat-shrinkable film to a film member having a tendency to warp at at least both ends in a second direction intersecting a first direction in which the apex of the warp extends; a step of detecting the warp of the film member; a step of heating the film laminate in which the warp of the film member has been detected to heat-shrink the heat-shrinkable film; and a step of peeling off the heat-shrinkable film from the film member.

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