Optical sheet and method for manufacturing the same

Abstract

The optical sheet (1) comprises: an optical functional film (10) having an optical functional layer (11) on which two or more different optical elements are arranged along one direction; and a protective film (20) having a protective layer (21) and an adhesive layer (22) and being provided on a pair of main surfaces of the optical functional film so as to be releasable via the adhesive layer (22). The protective film (20) extends outward from at least a portion of the periphery of the optical functional film (10), and a portion of the adhesive layer (22) is included in a portion of the protective film extending from at least a portion of the periphery of the optical functional film (10).

Description

Technical Field

[0001] The present disclosure relates to an optical sheet having an optical functional film and a protective film and a method for manufacturing the same. Background Art

[0002] Conventionally, there is known an optical functional film which is provided in an image display device such as a liquid crystal display device and which imparts an optical effect to image light formed by the image display device.

[0003] A protective film is usually attached to the optical functional film before being placed in an image display device, and such a protective film protects the optical functional film from impact, contamination, etc. during circulation or storage. Generally speaking, the protective film is attached to the optical functional film in a removable manner via an easily removable adhesive layer, and is removed when the optical functional film is placed in the image display device.

[0004] JP2013-76828A discloses an optical sheet having a louver film as an optical functional film and a protective film for protecting the louver film. The louver film is a multilayer structure including the following parts: an optical functional layer in which a light absorbing part and a light transmitting part are alternately arranged; a substrate layer supporting the optical functional layer; and a protective layer provided on the surface of the substrate layer opposite to the optical functional layer side. On the other hand, the protective film has a protective layer and an adhesive layer, and is provided on the optical functional film via the adhesive layer.

[0005] The optical sheet of JP2013-76828A is cut into a predetermined size by a die or the like from a laminated sheet formed by laminating a louvered film portion having a multilayer structure including an optical functional layer, a base layer, and a protective layer, and a protective film portion including a protective layer and an adhesive layer.

[0006] When cutting out as described above, it is sometimes difficult to smoothly cut the end face of the louver film because the louver film portion is multi-layered and the optical functional layer includes a light absorbing portion and a light transmitting portion made of different materials. In the technology of JP2013-76828A, a cutting method is studied to smooth the end face of the louver film. Summary of the invention

[0007] As described above, it is difficult to smoothly cut the end face of the louver film. If the end face is not smoothly formed, a portion of the end face is torn off to form a hole, or a peeling portion that is about to fall off is formed. Such a hole or peeling portion may be caused by a large pressure applied locally to the louver film from a tool (die, etc.). The hole and peeling portion will damage the appearance of the louver film.

[0008] On the other hand, the peeled portion may fall off during or after the installation of the shutter film on the image display device. In the event of such a fall, the peeled portion may become a foreign body in the image display device, which may adversely affect performance.

[0009] The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide an optical sheet and a method for producing the same which can suppress foreign matter that may be generated from an optical functional film from undesirably spreading inside an image display device or the like.

[0010] The optical sheet disclosed herein comprises: an optical functional film having an optical functional layer having two or more optical elements that are different from each other arranged in one direction; and a protective film having a protective layer and an adhesive layer, and being arranged on at least one of a pair of main surfaces of the optical functional film so as to be removably disposed via the adhesive layer, wherein the protective film extends outward from at least a portion of the periphery of the optical functional film, and a portion of the adhesive layer is included in a portion of the protective film extending from at least a portion of the periphery of the optical functional film.

[0011] The protective film may extend outward from the entire periphery of the optical functional film.

[0012] The protective films may be a pair, each provided on the pair of main surfaces of the optical functional film, and a peripheral edge of one of the pair of protective films may be bonded to a peripheral edge of the other protective film in a releasable manner.

[0013] In this case, the peripheral edge of the one protective film may protrude outward from the peripheral edge of the other protective film.

[0014] Furthermore, the protective film may extend from the periphery of the optical functional film by a distance in the range of 1 mm or more to 100 mm.

[0015] In addition, the optical functional film may have a thickness of 0.2 mm or more and 0.6 mm or less.

[0016] In addition, the Young's modulus of the protective film may be greater than or equal to 20 MPa and less than or equal to 110 MPa.

[0017] In addition, the bending stiffness of the protective film can be 1000 MPa·m 4 Above and 2000MPa·m 4 the following.

[0018] The optical functional film may be a louver film, and the optical element portion may include light absorbing portions and light transmitting portions that are alternately arranged.

[0019] In this case, the light absorbing portion may include a base resin and light absorbing particles held in the base resin.

[0020] In addition, the optical functional film may be formed by laminating a substrate and the optical functional layer in this order.

[0021] Furthermore, the optical functional film may be formed by laminating a first substrate, a reflective polarizing layer, an adhesive layer, the optical functional layer, and a second substrate in this order.

[0022] In addition, it may be that the optical element portions extend linearly in directions different from the one direction, and the optical functional film is formed into a rectangular shape by a pair of mutually parallel first sides and a pair of mutually parallel second sides, and the different directions are not parallel to the first side and the second side, respectively.

[0023] In addition, the method for manufacturing an optical sheet of the present disclosure comprises:

[0024] A step of preparing an optical functional film having an optical functional layer in which two or more different optical elements are arranged in one direction;

[0025] A step of preparing a protective film having a protective layer and an adhesive layer; and

[0026] a step of attaching the protective film to at least one of the pair of main surfaces of the optical functional film via the adhesive layer in a releasable manner;

[0027] The protective film is attached so as to extend outward from at least a portion of the periphery of the optical functional film.

[0028] A portion of the adhesive layer is included in a portion of the protective film that protrudes from at least a portion of the periphery of the optical functional film.

[0029] In the step of preparing the optical functional film, the optical functional film may be prepared by cutting the optical functional film into a rectangular shape from a laminated sheet including the optical functional layer.

[0030] The optical elements extend linearly in directions different from the one direction.

[0031] The optical functional film is formed into a rectangular shape by a pair of mutually parallel first sides and a pair of mutually parallel second sides, and is cut out from the laminated sheet so that the different directions are not parallel to the first sides and the second sides.

[0032] In addition, the method for manufacturing an optical sheet of the present disclosure comprises:

[0033] A step of preparing a laminated sheet having an optical function layer and an initial protective layer, wherein the optical function layer has two or more different optical elements arranged along one direction;

[0034] A step of cutting out an optically functional film having the optically functional layer and the initial protective layer from the laminated sheet;

[0035] A step of preparing a protective film having a protective layer and an adhesive layer; and

[0036] After removing the initial protective layer, the protective film is bonded to at least one of the pair of main surfaces of the optical functional film via the adhesive layer in a releasable manner.

[0037] The protective film is attached so as to extend outward from at least a portion of the periphery of the optical functional film.

[0038] A portion of the adhesive layer is located in a portion of the protective film that protrudes from at least a portion of the periphery of the optical functional film.

[0039] According to the present disclosure, it is possible to suppress foreign matter that may be generated from the optical functional film from being undesirably diffused inside an image display device or the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic cross-sectional view showing the layer structure of an optical sheet according to one embodiment of the present disclosure.

[0041] Figure 2 yes Figure 1 The optical sheet is shown in a top view and is Figure 1 The optical sheet is observed in the direction of arrow II.

[0042] Figure 3A Yes Description Figure 1 A diagram showing an example of a method for producing an optical sheet shown in FIG.

[0043] Figure 3B Yes Description Figure 1 A diagram showing an example of a method for producing an optical sheet shown in FIG.

[0044] Figure 3C Yes Description Figure 1 A diagram showing an example of a method for producing an optical sheet shown in FIG.

[0045] Figure 3D Yes Description Figure 1 A diagram showing an example of a method for producing an optical sheet shown in FIG.

[0046] Figure 4A Yes Description Figure 1 A diagram showing an example of a method for producing an optical sheet shown in FIG.

[0047] Figure 4B Yes Description Figure 1 A diagram showing an example of a method for producing an optical sheet shown in FIG.

[0048] Figure 5A Yes Description Figure 1 A diagram showing an example of a method for producing an optical sheet shown in FIG.

[0049] Figure 5B Yes Description Figure 1 A diagram showing an example of a method for producing an optical sheet shown in FIG.

[0050] Figure 5C Yes Description Figure 1 A diagram showing an example of a method for producing an optical sheet shown in FIG.

[0051] Figure 6 It is a summary of Figure 1 The optical sheet shown is an optically functional film of a liquid crystal display device.

[0052] Figure 7 It is shown Figure 1 A diagram showing a modified example of the optical sheet shown.

[0053] Figure 8 It is shown Figure 1 A diagram showing a modified example of the optical sheet shown.

[0054] Fig. 9 It is shown Figure 1 A diagram showing a modified example of the optical sheet shown.

[0055] Fig.10 It is shown Figure 1 A diagram showing a modified example of the optical sheet shown.

[0056] Fig.11 It is shown Figure 1 A diagram showing a modified example of the optical sheet shown.

[0057] Fig.12 It is shown Figure 1 A diagram showing a modified example of the optical sheet shown.

[0058] Fig.13A Yes Description Figure 1 A diagram showing a modified example of the method for producing an optical sheet shown.

[0059] Fig. 13B Yes Description Figure 1 A diagram showing a modified example of the method for producing an optical sheet shown.

[0060] Fig. 13C Yes Description Figure 1A diagram showing a modified example of the method for producing an optical sheet shown.

[0061] Fig.13D Yes Description Figure 1 A diagram showing a modified example of the method for producing an optical sheet shown.

[0062] Fig.13E Yes Description Figure 1 A diagram showing a modified example of the method for producing an optical sheet shown. DETAILED DESCRIPTION

[0063] Hereinafter, an optical sheet 1 and a method for manufacturing the same according to an embodiment of the present disclosure will be described with reference to the drawings. In the drawings attached to this specification, the proportions and aspect ratios are appropriately changed and exaggerated for ease of illustration and understanding.

[0064] In addition, in this specification, the terms "plate", "sheet", and "film" are not distinguished from each other based on the difference in name only. For example, "optical sheet" is a concept that also includes components that can be called plates or films, and therefore, "optical sheet" cannot be distinguished from components called "optical film" etc. only by name.

[0065] In addition, "sheet surface (plate surface, film surface)" refers to a surface that is consistent with the plane direction of the sheet-like (plate-like, film-like) component as a target when the sheet-like (plate-like, film-like) component as a target is observed as a whole and in a large area. In addition, the normal line of the sheet surface refers to a line perpendicular to the sheet surface, and the direction parallel to the normal line is called the normal line direction.

[0066] In addition, terms such as "parallel", "perpendicular", "same", etc., or values ​​of lengths and angles used in this specification to specify shapes and geometric conditions and their degrees are not limited to strict meanings, but are interpreted to include the degree to which the same function can be expected.

[0067] <Optical sheet>

[0068] Figure 1 This is a schematic cross-sectional view showing the layer structure of the optical sheet 1 according to the present embodiment. Figure 2 is a top view of the optical sheet 1, and is Figure 1 The optical sheet 1 is viewed in the direction of arrow II. Figure 1 and Figure 2The optical sheet 1 of the present embodiment shown comprises: an optical functional film 10, which has an optical functional layer 11 having two or more different optical elements arranged along one direction; and a pair of protective films 20, which have a protective layer 21 and an adhesive layer 22, and are freely arranged on at least one of a pair of main surfaces of the optical functional film 10 (both in this case) via the adhesive layer 22 so as to be peelable.

[0069] Next, the optical functional film 10 is provided on one of the pair of main surfaces ( Figure 1 The protective film 20 on the main surface (upper side) of the optical functional film 10 is referred to as the first protective film 20A, and the protective layer 21 and the adhesive layer 22 of the first protective film 20A are referred to as the first protective layer 21A and the first adhesive layer 22A, respectively. In addition, the protective film 20 provided on the other (lower) main surface of the pair of main surfaces of the optical functional film 10 is referred to as the second protective film 20B, and the protective layer 21 and the adhesive layer 22 of the second protective film 20B are referred to as the second protective layer 21B and the second adhesive layer 22B, respectively.

[0070] The optical functional film 10 is a louver film in this embodiment, and has: a film-shaped optical functional layer 11 having light absorbing parts 11a and light transmitting parts 11b as different optical elements arranged alternately along the film surface of the optical functional film 10; and a substrate 12, which is provided on one of a pair of main surfaces of the optical functional layer 11. The outer main surface of the substrate 12 constitutes the main surface of the optical functional film 10, and the first protective film 20A is provided on the main surface of the optical functional film 10 formed by the outer main surface of the substrate 12. In addition, the optical functional film 10 in this embodiment has a double-layer structure of the optical functional layer 11 and the substrate 12, but further functional layers may be added.

[0071] In the optical function layer 11, the light absorbing portion 11a and the light transmitting portion 11b are Figure 2 The plurality of layers are alternately arranged in a first direction D1 as shown in FIG. 1 , and extend linearly in a second direction D2 perpendicular to the first direction D1. Figure 2 As shown by the dotted line, the optical functional film 10 is formed into a rectangular shape by a pair of mutually parallel first sides 10a and a pair of mutually parallel second sides 10b. In other words, the optical functional film 10 is a rectangular shape with four sides formed by a pair of mutually parallel first sides 10a and a pair of mutually parallel second sides 10b. Here, the second direction D2 is not parallel to the first side 10a and the second side 10b.

[0072] When the optical functional film 10 is assembled in a liquid crystal display device, for example, the rectangular optical functional film 10 is arranged in parallel with the rectangular liquid crystal panel. At this time, if the direction in which the light absorbing portion 11a and the light transmitting portion 11b extend in a straight line, i.e., the second direction D2, is parallel to the first side 10a and the second side 10b, respectively, it is possible to generate moire fringes due to the relationship with the pixel arrangement. Therefore, in this embodiment, the light absorbing portion 11a and the light transmitting portion 11b are given a so-called bias. However, the second direction D2 may also be parallel to any of the first side 10a and the second side 10b.

[0073] The light absorbing portion 11a is a portion that absorbs light. In the present embodiment, the light absorbing portion 11a includes, for example, a substance in which a black filler is contained (in detail, dispersed) in a base resin (in other words, an adhesive resin). Furthermore, regarding the light absorbing portion 11a, light absorbing particles may be contained in the base resin (in other words, an adhesive resin). In this case, acrylic beads containing carbon black can be exemplified as light absorbing particles. Furthermore, in the case where the adhesive resin contains black filler or light absorbing particles, the black filler or light absorbing particles are not cross-linked with the adhesive resin.

[0074] The cross-sectional shape of the light absorbing portion 11a can be various shapes depending on the required function. In the present embodiment, Figure 1 As shown, the cross-sectional shape of the light absorbing portion 11a is a trapezoidal shape that tapers toward the light emitting side end. On the other hand, the cross-sectional shape of the light transmitting portion 11b is a trapezoidal shape that tapers toward the light incident side end. However, the cross-sectional shapes of the light absorbing portion 11a and the light transmitting portion 11b are not particularly limited and may also be rectangular.

[0075] The material constituting the base resin in the light absorbing portion 11a is not particularly limited, but is preferably a curable resin. Specifically, for example, there can be cited: an ionizing radiation curable resin which is a resin cured by ultraviolet rays or electron beams; a mixture of an ionizing radiation curable resin and a solvent drying resin (a resin that becomes a coating by simply drying a solvent added to adjust the solid content during coating); or a thermosetting resin, etc. The refractive index of the base resin in the light absorbing portion 11a is preferably greater than or equal to 1.47 and less than or equal to 1.65, and more preferably greater than or equal to 1.49 and less than or equal to 1.57. If the refractive index of the base resin is high, the light absorbing portion 11a is easily broken, so the refractive index is preferably less than or equal to 1.57.

[0076] On the other hand, the light-transmitting portion 11b is a portion through which light is transmitted. The light-transmitting portion 11b is, for example, made of a resin that is transparent to visible light. The material of the light-transmitting portion 11b is not particularly limited, but is preferably a curable resin. Specifically, for example, there can be cited: an ionizing radiation curable resin that is a resin that is cured by ultraviolet rays or electron beams; a mixture of an ionizing radiation curable resin and a solvent drying resin (a resin that becomes a coating by simply drying a solvent added to adjust the solid content during coating); or a thermosetting resin, etc.

[0077] The refractive index of the light-transmitting portion 11b is preferably greater than 1.47 and less than 1.65, and more preferably greater than 1.49 and less than 1.57. If the refractive index is high, the light-transmitting portion 11b is easily broken, so the refractive index is preferably less than 1.57. In addition, it is preferred that the refractive index of the light-transmitting portion 11b is higher than or the same as the refractive index of the base resin of the light-absorbing portion 11a. In the case where the refractive index of the light-transmitting portion 11b is higher than the refractive index of the base resin of the light-absorbing portion 11a, an optical design that utilizes total reflection of light from the light-transmitting portion 11b toward the light-absorbing portion 11a can be achieved, for example, the efficiency of light utilization can be improved. In addition, in the case where the refractive index of the light-transmitting portion 11b is the same as the refractive index of the base resin of the light-absorbing portion 11a, total reflection or refraction of light will not occur, so that, for example, even if the distance from the surface of the display device to the optical functional film 10 is far away, it is possible to prevent the generation of double images of the transmitted light and the total reflected light or the refracted light.

[0078] In addition, the spacing of the arrangement of the light absorbing portion 11a and the light transmitting portion 11b in the optical functional layer 11 is not particularly limited, but from the viewpoint of effectively exerting the function of the louver film, it is preferably 15 μm or more and 100 μm or less, and more preferably 30 μm or more and 100 μm or less. In addition, the height (thickness) of the light absorbing portion 11a is preferably 60 μm or more and 150 μm or less, and more preferably 60 μm or more and 150 μm or less. In addition, the optical functional layer 11 includes a film-like connecting plate portion 11c that is integral with the light transmitting portion 11b and connected to each light transmitting portion 11b in a manner that supports each light transmitting portion 11b together. The thickness of the connecting plate portion 11c is preferably 10 μm or more and 50 μm or less.

[0079] The substrate 12 is a transparent substrate having light transmittance made of resin or glass, for example, a film or glass with triacetyl cellulose (TAC), polyethylene terephthalate (PET), polyolefin, polycarbonate, polyacrylate, or polyamide as the main component. The thickness of the substrate 12 is, for example, 60 μm or more and 250 μm or less. In addition, the refractive index of the substrate 12 is, for example, 1.46 or more and 1.67 or less. In addition, the main component refers to a component contained in a proportion of 50% or more relative to the whole substance or a component contained in the largest amount among the multiple components constituting a substance.

[0080] Next, the first protective film 20A and the second protective film 20B are provided to protect the optical functional film 10 from impact or contamination during circulation or storage, and are removed when the optical functional film 10 is provided in, for example, a liquid crystal display device. Figure 1 and Figure 2 As shown in FIG. 1 , the first protective film 20A and the second protective film 20B in the present embodiment extend outward from the entire periphery of the optical functional film 10. In the first protective film 20A, the first adhesive layer 22A is provided on the entire principal surface of the first protective layer 21A, and in the second protective film 20B, the second adhesive layer 22B is also provided on the entire principal surface of the second protective layer 21B. Therefore, a portion of the first protective film 20A extending from the periphery of the optical functional film 10 includes a portion of the first adhesive layer 22A, and a portion of the second protective film 20B extending from the periphery of the optical functional film 10 includes a portion of the second adhesive layer 22B.

[0081] When the first protective film 20A and the second protective film 20B are provided so as to extend outward from the entire area of ​​the periphery of the optical functional film 10 and cover the optical functional film 10 from both main surfaces, the optical functional film 10 can be effectively protected. Figure 1 As shown, the periphery of the first protective film 20A and the periphery of the second protective film 20B are bonded to each other in a releasable manner, thereby further improving the reliability of the protective function. However, the periphery of the first protective film 20A and the periphery of the second protective film 20B may be separated.

[0082] exist Figure 1, the extension amount T of the first protective film 20A relative to the optical functional film 10 in a direction parallel to the film surface is shown. In the present embodiment, for example, it is assumed that the thickness of the optical functional film 10 is set to be greater than 0.2 mm and less than 0.6 mm. In this case, the extension amount T is preferably greater than 1 mm and less than 100 mm, and more preferably greater than 1 mm and less than 10 mm. This is because, in this case, the first protective film 20A can be used to cover the entire area or most of the surface of the periphery of the optical functional film 10. The preferred size range of the extension amount T is commonly preferred in the entire area of ​​the periphery of the optical functional film 10, and therefore, the first protective film 20A and the second protective film 20B can be arranged in a manner that extends from a part or the entire area of ​​the periphery of the optical functional film 10 in a range of greater than 1 mm to 100 mm, particularly in a range of greater than 1 mm and less than 10 mm. However, the extension amount T may be less than 1 mm or greater than 100 mm.

[0083] The Young's modulus of the first protective film 20A and the second protective film 20B is preferably 20 MPa or more and 110 MPa or less, and the bending rigidity is preferably 1000 MPa·m. 4 Above and 2000MPa·m 4 Within such a range, the first protective film 20A and the second protective film 20B become soft and can easily cover the peripheral surface of the optical functional film 10 .

[0084] The material forming the first protective layer 21A and the second protective layer 21B in the first protective film 20A and the second protective film 20B is not particularly limited, but considering the flexibility of the first protective film 20A and the second protective film 20B, a film containing polyethylene, polypropylene or the like as a main component, which is a relatively soft material, is preferred.

[0085] On the other hand, the materials forming the first adhesive layer 22A and the second adhesive layer 22B are not particularly limited, and can be formed of, for example, acrylic adhesives, silicone adhesives, polyurethane adhesives, rubber adhesives, etc. The adhesive strength of the first adhesive layer 22A and the second adhesive layer 22B is preferably greater than or equal to 0.05 N / 25 mm and less than or equal to 0.2 N / 25 mm.

[0086] In addition, the thickness of the first protective film 20A and the second protective film 20B is preferably 25 μm or more and 150 μm or less. The thickness of the first protective layer 21A and the second protective layer 21B is preferably 20 μm or more and 100 μm or less. In addition, the thickness of the first adhesive layer 22A and the second adhesive layer 22B is preferably 5 μm or more and 50 μm or less.

[0087] <Method for producing optical sheet>

[0088] Next, use Figures 3A to 3D , Figures 4A to 4B , Figures 5A to 5C An example of a method for producing the optical sheet 1 will be described.

[0089] Here, in the example described, first, a laminated sheet 100 including an optical function layer 11 and a substrate 12 is prepared. Figure 3A As shown, a light-transmitting material layer 11bR is provided on the substrate 12. The light-transmitting material layer 11bR is formed of, for example, a curable resin before curing, and can be continuously applied on the substrate 12 conveyed by a roller.

[0090] Then, if Figure 3B As shown, the recessed portion 14 for filling the light absorbing portion 11a is formed on the light transmissive portion material layer 11bR by a mold. Such molding can also be performed using a roller mold. And, by curing the light transmissive portion material layer 11bR, the light transmissive portion 11b is formed between adjacent recessed portions 14.

[0091] Then, if Figure 3C As shown, the light absorbing material layer 11aR is provided so as to fill the recessed portion 14 and span the plurality of light transmitting portions 11b. The light absorbing material layer 11aR contains, for example, a curable resin as a base resin before curing, and is formed of a material containing a black filler.

[0092] Then, if Figure 3D As shown in FIG. 1 , the light absorbing portion material layer 11aR is filled in the concave portion 14 and the excess light absorbing portion material layer 11aR is removed by scraping the light absorbing portion material layer 11aR with a scraper or the like. Then, the light absorbing portion 11a is formed by curing the light absorbing portion material layer 11aR. Thus, the laminated sheet 100 including the optical function layer 11 and the substrate 12 is manufactured.

[0093] Then, if Figure 4A As shown, the laminated sheet 100 is rolled into a roll to form a roll body. Here, the longitudinal direction of the light absorbing portion 11a and the light transmitting portion 11b coincides with the longitudinal direction of the laminated sheet 100, that is, coincides with the winding direction.

[0094] Then, if Figure 4B As shown, the laminated sheet 100 is fed out, and a rectangular optical functional film 10 is cut out by a punch 200. Here, the optical functional film 10 is formed into a rectangular shape by a pair of mutually parallel first sides 10a and a pair of mutually parallel second sides 10b, but the optical functional film 10 is cut out from the laminated sheet 100 in a manner that the longitudinal direction of the light absorbing portion 11a and the light transmitting portion 11b, i.e., the second direction D2, is not parallel to the first side 10a and the second side 10b, respectively. In order to perform such cutting, the punch 200 having a rectangular blade is positioned in a manner not parallel to the longitudinal direction of the laminated sheet 100 and is operated.

[0095] As above, Figure 5A As shown, the optical functional film 10 is prepared. Then, as Figure 5B As shown in FIG. 1 , a first protective film 20A and a second protective film 20B are also prepared, and the first protective film 20A and the second protective film 20B are attached to the two main surfaces of the optical functional film 10. Then, as shown in FIG. Figure 5C As shown, the first protective film 20A and the second protective film 20B are bonded in a manner that extends outward from at least a portion of the periphery of the optical functional film 10, thereby producing an optical sheet 1 as follows: a portion of the first adhesive layer 22A is included in a portion of the first protective film 20A extending from at least a portion of the periphery of the optical functional film 10, and a portion of the second adhesive layer 22B is included in a portion of the second protective film 20B.

[0096] <Example of use of optical sheet 1>

[0097] Here, a usage example of the optical sheet 1 will be described. Figure 6 1 is a diagram schematically showing a liquid crystal display device, wherein the liquid crystal display device includes an optical functional film 10 obtained by removing a first protective film 20A and a second protective film 20B from an optical sheet 1. When the optical functional film 10 is assembled to the liquid crystal display device, the first protective film 20A and the second protective film 20B are removed from the optical sheet 1 in a factory, etc., and then the optical functional film 10 is assembled to the liquid crystal display device. Figure 6 The liquid crystal display device shown includes a light source 2 , a prism sheet 3 , a reflective polarization separation sheet 30 , an optical functional film 10 , a liquid crystal panel 50 , and a visibility adjustment sheet 60 in this order.

[0098] <Effects>

[0099] The optical sheet 1 of the present embodiment described above comprises: an optical functional film 10, which has an optical functional layer 11 having two or more different optical element portions (11a, 11b) arranged along one direction; and a protective film 20, which has a protective layer 21 and an adhesive layer 22, and is freely disposed on at least one of a pair of main surfaces of the optical functional film 10 via the adhesive layer 22, wherein the protective film 20 extends outward from at least a portion of the periphery of the optical functional film 10, and a portion of the adhesive layer 22 is included in a portion of the protective film 20 extending from at least a portion of the periphery of the optical functional film 10.

[0100] In such a structure, the parts on the peripheral surface (end surface) of the optical functional film 10 that may become foreign matter due to falling off from the optical functional film 10 or the foreign matter are held by the part of the protective film 20 extending from the optical functional film 10, especially by the adhesive layer 22, and are difficult to fall off. In addition, when the protective film 20 is removed from the optical functional film 10, the parts on the peripheral surface of the optical functional film 10 that may become foreign matter or the foreign matter are easily attached to the adhesive layer 22 in the extending part. Thereby, it is possible to suppress the situation where foreign matter that may be generated from the optical functional film 10 spreads undesirably inside the image display device, etc. That is, Figure 6 As shown, after the optical functional film 10 is assembled in a liquid crystal display device, etc., foreign matter that may be generated from the optical functional film 10 can be suppressed from diffusing inside the liquid crystal display device, etc., thereby avoiding affecting the quality of the liquid crystal display device, etc.

[0101] Furthermore, the foreign matter may be part of or in Figure 4B Such a problem is likely to occur when the optical functional film 10 is cut out.

[0102] Moreover, in this embodiment, the protective film 20 protrudes outward from the entire area of ​​the periphery of the optical functional film 10. Thereby, the reliability of the foreign matter diffusion suppression function of the protective film 20 can be improved.

[0103] In addition, the protective film 20 is composed of a pair of protective films, namely, a first protective film 20A and a second protective film 20B, and is respectively provided on a pair of main surfaces of the optical functional film 10. Moreover, the periphery of the first protective film 20A and the periphery of the second protective film 20B are bonded in a peelable manner. Thus, the reliability of the foreign matter diffusion suppression function of the first protective film 20A and the second protective film 20B can be improved, and the reliability of the protection function from impact, contamination, etc. can also be effectively improved.

[0104] In addition, the first protective film 20A and the second protective film 20B extend in a range of 1 mm to 100 mm (preferably 1 mm to 10 mm) from the periphery of the optical functional film 10. Thus, a reduction in operability due to excessive enlargement of the protective film can be avoided, and the periphery of the optical functional film 10 can be covered in a sufficient range by the first protective film 20A and the second protective film 20B.

[0105] In addition, the Young's modulus of the first protective film 20A and the second protective film 20B is preferably 20 MPa or more and 110 MPa or less. In addition, the bending rigidity of the first protective film 20A and the second protective film 20B is preferably 1000 MPa·m 4 Above and 2000MPa·m 4In this case, the first protective film 20A and the second protective film 20B are moderately soft, and the periphery of the optical functional film 10 can be easily covered with the first protective film 20A and the second protective film 20B.

[0106] In addition, particularly in the present embodiment, the optical functional film 10 is a louver film, comprising light absorbing parts 11a and light transmitting parts 11b arranged alternately with each other, and the light absorbing parts 11a contain light absorbing particles. Generally, in the louver film, the refractive index of the light transmitting part is higher than that of the light absorbing part, and correspondingly, the light transmitting part becomes harder than the light absorbing part, and parts that may become foreign matter are easily generated when cut out. Furthermore, in the case where the light absorbing part contains light absorbing particles, parts that may become foreign matter are easily generated from the light absorbing part when cut out. Therefore, according to the optical sheet 1 of the present embodiment, compared with the case of an optical sheet formed by bonding a protective film to the optical functional film in a coplanar manner, the yield rate of the device that is the assembly target of the optical functional film can be significantly improved, thereby being able to provide a greater advantage at the manufacturing site.

[0107] <Modification>

[0108] Various modifications of the above-described embodiment will be described below.

[0109] exist Figure 7 In the modification 1 shown, the layer structure of the optical functional film 10 is different from that of the above-mentioned embodiment. That is, the optical functional film 10 of the modification 1 is formed by laminating the back side substrate 16 (corresponding to the first substrate), the reflective polarizing layer 17, the adhesive layer 18, the optical functional layer 11 and the substrate 12 (corresponding to the second substrate) which are the same as those in the above-mentioned embodiment in this order. The first protective film 20A covers the substrate 12, and the second protective film 20B covers the back side substrate 16.

[0110] The more layers that constitute the optical functional film 10, the more likely it is that a portion that may become foreign matter will be generated on the end surface of the optical functional film 10 when it is cut. Therefore, in this modification 1, it is possible to effectively suppress the spread of foreign matter that may be generated from the optical functional film 10 in a liquid crystal display device or the like.

[0111] exist Figure 8 In the variation 2 shown, the layer structure of the optical functional film 10 is different from that of the above-mentioned embodiment. That is, the optical functional film 10 of variation 2 has the protective film 20 only on one side of the optical functional film 10. The protective film 20 is provided in a manner of hanging down from the periphery of the optical functional film 10, and the adhesive layer 22 of the protective film 20 is not attached to the periphery of the optical functional film 10.

[0112] In Modification 2, the portion or foreign matter that may become foreign matter due to falling off from the optical functional film 10 on the peripheral surface (end surface) of the optical functional film 10 is also difficult to fall off due to the protective film 20. In addition, when the protective film 20 is removed, the portion or foreign matter that may become foreign matter on the peripheral surface of the optical functional film 10 is easy to adhere to the adhesive layer 22 in the protruding portion. Thus, it is possible to suppress the situation where foreign matter that may be generated from the optical functional film 10 is spread undesirably inside the image display device, etc.

[0113] Fig. 9 The optical functional film 10 of Modification 3 shown has the protective film 20 only on one side of the optical functional film 10 , similarly to Modification 2. However, the protective film 20 is attached to the periphery of the optical functional film 10 .

[0114] According to such modification 3, the effect of suppressing the diffusion of foreign matter can be enhanced.

[0115] exist Fig.10 In the modification 4 shown, the morphology of the first protective film 20A and the second protective film 20B is different from the above-mentioned embodiment. That is, in the modification 4, the periphery of the first protective film 20A protrudes outward from the periphery of the second protective film 20B. The first protective film 20A may protrude more than 1 mm relative to the second protective film 20B.

[0116] In the fourth modification, the first protective film 20A and the second protective film 20B bonded to each other can be easily peeled off.

[0117] exist Fig.11 In the fifth modification shown, the first protective film 20A and the second protective film 20B are different from the above-described embodiment. That is, in the fifth modification, the first protective film 20A and the second protective film 20B extend only from a part (two sides) of the optical functional film 10 .

[0118] exist Fig.12 In the modification 6 shown, the optical functional film 10 is not a louver film, but a so-called viewing angle widening film. In the optical functional film 10 as a viewing angle widening film shown in the figure, the optical functional layer 11 is composed of a high refractive index layer 11H and a low refractive index layer 11L, and the interface between the high refractive index layer 11H and the low refractive index layer 11L is a concave-convex shape. On the surface of the high refractive index layer 11H on the opposite side to the low refractive index layer 11L side, a substrate 12 is provided via an adhesive layer 19.

[0119] In the layer composed of the high refractive index layer 11H and the low refractive index layer 11L, one side is harder than the other side, so that a part that may become a foreign matter is easily produced when cutting out. In Modification 6, the first protective film 20A and the second protective film 20B can effectively suppress the diffusion of foreign matter. In addition, the optical functional film 10 can also be a film other than a louver film and a viewing angle expansion film.

[0120] Next, use Figures 13A to 13E Modifications of the production method of the above-described embodiment will be described.

[0121] exist Fig.13A 1 shows a laminated sheet 110 in which a first initial protective layer 24, an optical functional layer 11, a substrate 12, and a second initial protective layer 25 are laminated in this order. Fig. 13B and Fig. 13C As shown, the optical functional film 10 with the initial protective layer is cut out using a punching die 200 .

[0122] Then, if Fig.13D As shown, the first initial protective layer 24 and the second initial protective layer 25 are removed from the optical functional film 10. Then, as Fig.13E As shown, the first protective film 20A and the second protective film 20B are prepared and bonded to the optical functional film 10. After the first initial protective layer 24 and the second initial protective layer 25 are removed from the optical functional film 10, for example, an inspection process of the optical functional film 10 may be performed.

[0123] Example

[0124] Next, examples of the present disclosure and comparative examples thereof will be described, but the present disclosure is not limited to these examples.

[0125] (Example)

[0126] As an example, a Figure 1 The layer structure of the optical sheet 1 is shown.

[0127] As a material forming the light absorbing portion 11 a of the optical functional layer 11 in the optical functional film 10 , a material (light absorbing portion material layer 11 aR) containing 5 wt % of carbon black in a base resin including thermosetting urethane acrylate and silicone resin was used.

[0128] As a material forming the light-transmitting portion 11 b , ultraviolet curing type urethane acrylate (light-transmitting portion material layer 11 bR) was used.

[0129] As a material forming the substrate 12 in the optical functional film 10 , a polycarbonate film (Carboglass Film C110 manufactured by AGC Corporation) having a thickness of 100 μm was used.

[0130] As a material for forming the protective film 20, a protective film having a thickness of 43 μm (EC-7520 manufactured by SUMIRON) was used, which had a protective layer 21 made of polypropylene and an adhesive layer 22 made of an acrylic adhesive.

[0131] In the example, first, a laminated sheet 100 in which the optical functional film 10 and the base material 12 were laminated was prepared.

[0132] When the laminated sheet 100 is produced, first, the connection pad portion 11c (see FIG. 1 ) is formed on the ultraviolet curable urethane acrylate (light-transmitting portion material layer 11bR) provided on the substrate 12 to form the light-transmitting portion 11b. Figure 1 ) is 25 μm. A roller mold is used to form the recessed portion 14 so that the depth of the recessed portion 14 is 102 μm, that is, the height of the light absorbing portion 11a is 102 μm. The pitch of the projections is set to 39 μm.

[0133] Next, the concave portion 14 is filled with a thermosetting resin (light absorbing material layer 11aR) containing carbon black, and then the light absorbing material layer 11aR is scraped off with a scraper or the like to remove excess light absorbing material layer 11aR. The light absorbing material layer 11aR is then thermally cured to produce the laminated sheet 100.

[0134] Then, a rectangular optical functional film 10 was cut out from the laminated sheet 100 using a punch cutter. Then, a protective film 20 was bonded to the optical functional film 10. The protective film 20 protruded from each side of the optical functional film 10 by 10 mm.

[0135] (Comparative Example)

[0136] As a comparative example, the following optical sheet was prepared: Figure 1 The layer structure shown, but the protective film does not extend from the optically functional film.

[0137] In the comparative example, the same laminated sheet 100 as in the example was used, but a protective film was attached to the laminated sheet 100 before cutting. Then, a rectangular optical functional film was cut out from the laminated sheet 100 with the protective film using a punch cutter. Therefore, the protective film and the optical functional film were in the same plane.

[0138] (evaluate)

[0139] As evaluations of Examples and Comparative Examples, it was verified whether portions existing on the end surface of the optical functional film and possibly falling off and becoming foreign matter adhered to the protective film or remained on the optical functional film side when the protective film was removed from the optical functional film.

[0140] As a result, in the example, it was confirmed that foreign matter adhered to the protective film 20 when the protective film 20 was removed from the optical functional film 10. On the other hand, in the comparative example, no foreign matter was confirmed on the protective film removed from the optical functional film, and a portion that could become a foreign matter due to detachment remained on the end surface of the optical functional film.

[0141] The above evaluation results confirm that when the protective film 20 is removed from the optical functional film 10, the portion that may become foreign matter on the peripheral surface of the optical functional film 10 or foreign matter is easily attached to the adhesive layer 22 in the protruding portion. Thus, the foreign matter diffusion suppression effect of the present disclosure is confirmed.

Claims

1. An optical sheet, wherein: The optical sheet comprises: An optically functional film having an optically functional layer in which two or more optical elements different from each other are arranged in one direction; and a protective film having a protective layer and an adhesive layer, and being releasably provided on at least one of the pair of main surfaces of the optical functional film via the adhesive layer; The protective film extends outward from at least a portion of the periphery of the optical functional film by a range of 1 mm to 10 mm. A portion of the protective film extending from at least a portion of the periphery of the optical functional film includes a portion of the adhesive layer. The optical functional film is a louver film, and the optical element portion includes a light absorbing portion and a light transmitting portion that are alternately arranged. The refractive index of the light-transmitting portion is greater than or equal to 1.49 and less than or equal to 1.

57. The optical functional film is formed by laminating a substrate and the optical functional layer in this order.

2. The optical sheet according to claim 1, wherein: The protective film extends outward from the entire periphery of the optical functional film.

3. The optical sheet according to claim 1 or 2, wherein: The protective films are a pair, and are respectively disposed on the pair of main surfaces of the optical functional film. The peripheral edge of one of the pair of protective films is bonded to the peripheral edge of the other protective film in a releasable manner.

4. The optical sheet according to claim 3, wherein: The peripheral edge of the one protective film protrudes outward from the peripheral edge of the other protective film.

5. The optical sheet according to claim 1, wherein: The optical functional film has a thickness of 0.2 mm or more and 0.6 mm or less.

6. The optical sheet according to claim 1, wherein: The protective film has a Young's modulus of 20 MPa or more and 110 MPa or less.

7. The optical sheet according to claim 1, wherein: The bending stiffness of the protective film is 1000MPa•m 4 Above and 2000MPa•m 4 the following.

8. The optical sheet according to claim 1, wherein: The light absorbing portion includes a base resin and light absorbing particles held in the base resin.

9. The optical sheet according to claim 1, wherein: The optical functional film is formed by laminating a first substrate, a reflective polarizing layer, an adhesive layer, the optical functional layer, and the substrate in this order.

10. The optical sheet according to claim 1, wherein: The optical elements extend linearly in directions different from the one direction. The optical functional film is formed into a rectangular shape by a pair of first sides parallel to each other and a pair of second sides parallel to each other, and the different directions are not parallel to the first sides and the second sides.

11. A method for manufacturing an optical sheet, wherein: The method for manufacturing the optical sheet comprises: A step of preparing an optical functional film having an optical functional layer in which two or more different optical elements are arranged in one direction; A step of preparing a protective film having a protective layer and an adhesive layer; as well as a step of attaching the protective film to at least one of the pair of main surfaces of the optical functional film via the adhesive layer in a releasable manner; The protective film is bonded so as to protrude outward from at least a portion of the periphery of the optical functional film by a range of 1 mm to 10 mm. A portion of the protective film extending from at least a portion of the periphery of the optical functional film includes a portion of the adhesive layer. The optical functional film is a louver film, and the optical element portion includes a light absorbing portion and a light transmitting portion that are alternately arranged. The refractive index of the light-transmitting portion is greater than or equal to 1.49 and less than or equal to 1.

57. The optical functional film is formed by laminating a substrate and the optical functional layer in this order.

12. The method for manufacturing an optical sheet according to claim 11, wherein: In the step of preparing the optical functional film, the optical functional film is prepared by cutting the optical functional film into a rectangular shape from a laminated sheet including the optical functional layer. The optical elements extend linearly in directions different from the one direction. The optical functional film is formed into a rectangular shape by a pair of mutually parallel first sides and a pair of mutually parallel second sides, and is cut out from the laminated sheet so that the different directions are not parallel to the first sides and the second sides.

13. A method for manufacturing an optical sheet, wherein: The method for manufacturing the optical sheet comprises: A step of preparing a laminated sheet having an optical function layer and an initial protective layer, wherein the optical function layer has two or more different optical elements arranged along one direction; A step of cutting out an optically functional film having the optically functional layer and the initial protective layer from the laminated sheet; A step of preparing a protective film having a protective layer and an adhesive layer; and After removing the initial protective layer, the protective film is bonded to at least one of the pair of main surfaces of the optical functional film via the adhesive layer in a releasable manner. The protective film is bonded so as to protrude outward from at least a portion of the periphery of the optical functional film by a range of 1 mm to 10 mm. A portion of the adhesive layer is located in a portion of the protective film extending from at least a portion of the periphery of the optical functional film. The optical functional film is a louver film, and the optical element portion includes a light absorbing portion and a light transmitting portion that are alternately arranged. The refractive index of the light-transmitting portion is greater than or equal to 1.49 and less than or equal to 1.

57. The optical functional film is formed by laminating a substrate and the optical functional layer in this order.

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