TW201818098A - Laminated optical film and image display device wherein display unevenness of the image display device is unlikely to occur even if the aforementioned laminated optical film is peeled off from the sticker, - Google Patents

Abstract

A laminated optical film of the present invention includes: an optical film having an optically anisotropic film; and a peeling film for protection, which is peelably affixed to the surface of the optical film through an adhesive layer; and the adhesive layer has a shear stress of 22 N/cm<2> or less, a sticker is peelably affixed to the surface of the peeling film for protection. The effect of this invention lies in that display unevenness is unlikely to occur even if the aforementioned laminated optical film is peeled off from the sticker.

Description

Laminated optical film and image display device

The present invention relates to a laminated optical film and the like.

BACKGROUND OF THE INVENTION Conventionally, various optical films have been used as constituent members of image display devices such as liquid crystal display devices or projectors, polarizing filters for photographing devices such as polarized sunglasses and cameras. For example, as an optical film used as a constituent member of a liquid crystal display device, a laminated body having a retardation film, a polarizing film, and a protective film is generally used. The optical film is also called a polarizing plate. A liquid crystal display device is obtained by assembling various structural members such as an optical film, a liquid crystal cell, a backlight, a frame including a frame, and a power cord. Generally, this does not mean that all of these constituent members are manufactured by the manufacturer of the liquid crystal display device, but that each constituent member is manufactured separately from the manufacturing of the liquid crystal display device. In other words, most manufacturers of liquid crystal display devices (manufacturers of finished products) purchase various components from manufacturers of optical films and backlights (manufacturers of parts), and then assemble the liquid crystal display devices by assembling them. In order to prevent the finished product or parts from being damaged during storage and transportation, various countermeasures are adopted. For example, a protective film is attached to an optical film assembled as a liquid crystal display device or an optical film used as a part before assembly to protect the surface thereof. This protective release film is often attached by the manufacturer of the finished product or the manufacturer of the component. In addition, the above-mentioned protective release film is also referred to as a product protection film, and is detachably attached to the surface of the optical film in order to be easily peeled off by human labor.

In addition, a sticker with various information may be attached to the surface of the protective peeling film. The information provided for the sticker includes, for example, various marks or numbers such as barcodes, two-dimensional codes, and other optical device reading marks and storage numbers. The information provided by the sticker is used in the manufacturing process, and the sticker is finally peeled off from the surface of the protective release film and removed.

SUMMARY OF THE INVENTION However, when the sticker is peeled from the surface of the protective peeling film, and the protective peeling film is further peeled and the liquid crystal display device is driven, display unevenness (blurred white stains) like traces of the sticker may occur on the screen. ). Problems to be solved by the invention

An object of the present invention is to provide a laminated optical film and an image display device that are less prone to display unevenness even when a peelable sticker is attached. Means to solve the problem

The inventors have found that, as described above, when the protective film is peeled off after the sticker is peeled off, a problem of uneven display occurs on the screen. Regarding the cause of this problem, I understand the following. First, when not only a peeling sticker but also a protective peeling film in a state where the sticker is attached is peeled from the screen, the aforementioned display unevenness does not occur. From this, it is presumed that only peeling off the sticker first is the cause of uneven display. Next, when the protective release film was peeled off the screen immediately after the sticker was peeled off, display unevenness did not occur. However, when the sticker was peeled off, and the protective film was left for a predetermined period of time, the display unevenness occurred. From these studies, it was found that the adhesive layer for attaching a protective release film to a screen affects display unevenness, and completed the present invention.

The laminated optical film of the present invention includes: an optical film having an optically anisotropic film; and a protective release film that is releasably attached to the surface of the optical film through an adhesive layer; and a shear of the adhesive layer The shear stress is 22 N / cm ² or less.

In the preferred laminated optical film of the present invention, the shear stress of the adhesive layer is 3 N / cm ² or more. In a preferred laminated optical film of the present invention, a peelable sticker is attached to the surface of the protective peeling film. A preferred laminated optical film of the present invention is the aforementioned optical film having the aforementioned optical anisotropic film, and a protective film laminated on the surface of the aforementioned optical anisotropic film. The preferred laminated optical film of the present invention is that the optically anisotropic film includes a retardation film.

According to another aspect of the present invention, an image display device is provided. An image display device according to the present invention includes the laminated optical film. Invention effect

Even if the laminated optical film of the present invention attaches a sticker to the surface of a protective peeling film and peels the sticker, and further peels off the protective peeling film, display unevenness is unlikely to occur. The laminated optical film can be suitably used as an optical component of an image display device.

Forms for Implementing the Invention In this specification, although ordinal numbers such as "1" or "2" are added before the terms, this ordinal number is used to distinguish the ordinal number added to the term and does not It has special meanings such as the pros and cons of the terms. In addition, in this specification, the numerical value connected with "~" means the numerical range which included the numerical value before and after "~" as a lower limit and an upper limit. When multiple lower limit values and multiple upper limit values are individually recorded, any lower limit value and upper limit value can be selected and connected with "~". It should be noted that the dimensions and thickness ratios shown in the drawings and the relative ratios between the components are different from the actual ones.

[Laminated Optical Film] The laminated optical film of the present invention includes an optical film and a protective release film that is releasably attached to the surface of the optical film through an adhesive layer. The optical film includes an optically anisotropic film and a protective film laminated on a surface side of the optically anisotropic film. The present invention is characterized in that, as an adhesive layer for attaching a protective release film to an optical film, an adhesive layer having a shear stress of 22 N / cm ² or less is used.

Fig. 1 is a perspective view of a laminated optical film according to a first embodiment, and Fig. 2 is a sectional view thereof. In FIGS. 1 and 2, the laminated optical film 1 includes an optical film 2 and a protective release film 3. As shown in FIG. 2, the optical film 2 includes a protective film 21, a polarizing film 22, and a retardation film 23 in this order from the surface side. These films (the protective film 21 and the polarizing film 22, and the polarizing film 22 and the retardation film 23) are adhered in a non-peelable manner through an appropriate adhesive or an adhesive (not shown). In addition, when the films are materials that can adhere to each other, the protective film 21 and the polarizing film 22 and the polarizing film 22 and the retardation film 23 may be directly adhered without using an adhesive or the like. An adhesive layer 4 is provided on the back surface of the protective release film 3. Through the adhesive layer 4, the protective release film 3 is detachably attached to the surface of the protective film 21 of the optical film 2. The surface of the protective release film 3 is the surface constituting the laminated optical film 1. Here, the above-mentioned non-peelable method means that the two films to be bonded are bonded with a degree of bonding strength that cannot be peeled off by human labor, or that the film material is damaged when the two films are peeled off. Then intensity followed. The above-mentioned peelable attachment means that the two films are adhered with the adhesive strength to the extent that they can be peeled off manually.

3 to 6 are sectional views of the laminated optical film according to the second to fifth embodiments. The perspective view of the laminated optical film of these embodiments as viewed from the front side is the same as that of FIG. 1. The second embodiment is different from the first embodiment in that a surface treatment layer 24 is provided on the surface of the protective film 21. That is, as shown in FIG. 3, the optical film 2 of the second embodiment includes a surface treatment layer 24, a protective film 21, a polarizing film 22, and a retardation film 23 in this order from the surface side. The surface treatment layer 24 is also adhered to the protective film 21 in a non-peelable manner. In the present embodiment, the surface of the surface treatment layer 24 is the surface constituting the optical film 2. Therefore, the protective release film 3 is releasably attached to the surface of the surface treatment layer 24. Examples of the surface treatment layer 24 include an anti-glare layer and a hard coat layer.

The third embodiment differs from the optical anisotropic film in that the optically anisotropic film is composed of a polarizing film and a plurality of (for example, two) retardation films. 1 EMBODIMENT. That is, as shown in FIG. 4, the optical film 2 according to the third embodiment includes a protective film 21, a polarizing film 22, a first retardation film 231, and a second retardation film 232 in this order from the surface side. These films are adhered through an adhesive or an adhesive (not shown, such as an adhesive or an adhesive). The retardation films 231 and 232 are generally films having different birefringence.

The fourth embodiment is different from the first embodiment in that a protective film is provided on the back side. That is, as shown in FIG. 5, the optical film 2 according to the fourth embodiment includes a first protective film 211, a polarizing film 22, a retardation film 23, and a second protective film 212 in this order from the surface side. These films are adhered in a non-peelable manner through an adhesive or an adhesive (not shown). The protective films 211 and 212 may be films of the same material and thickness, or may be films of different materials or thicknesses.

The fifth embodiment is also different from the first embodiment in that a protective release film is detachably attached to the back side of the optical film. That is, as shown in FIG. 6, the laminated optical film 1 according to the fifth embodiment includes, in order from the surface side, a first protective release film 31, a first adhesive layer 41, and an optical film 2 (for example, a protective film 21, a polarized light). The film 22 and the retardation film 23), the second adhesive layer 42 and the second protective release film 32. The first protective release film 31 is detachably attached to the surface of the optical film 2 through the first adhesive layer 41, and the second protective release film 32 is detachable through the second adhesive layer 42. It is attached to the back surface of the optical film 2. When two protective release films are provided as in this embodiment, the protective release films 31 and 32 may be films having the same material and thickness, or films having different materials or thicknesses. In addition, although at least one of the first adhesive layer 41 and the second adhesive layer 42 may be an adhesive layer having a shear stress of 22 N / cm ² or less, the first adhesive layer 41 and the first adhesive layer 41 and The shear stress on both sides of the second adhesive layer 42 is 22 N / cm ² or less.

In addition, although not shown in the drawings, the respective embodiments described above may be appropriately combined. For example, the second protective peeling film of the fifth embodiment may be provided in the laminated optical film of the layer structure of the second embodiment, the third embodiment, or the fourth embodiment. In addition, although the laminated optical film of each of the embodiments described above includes an optically anisotropic film including a polarizing film and a retardation film, the optically anisotropic film may be composed of only a polarizing film or only a retardation film, for example.

The sixth embodiment is different from each of the above-mentioned embodiments in that a sticker is detachably attached to the surface of the protective release film. That is, as shown in FIGS. 7 and 8, the laminated optical film 1 according to the sixth embodiment includes a protective release film 3, an adhesive layer 4, and an optical film 2 (for example, a protective film 21, a polarizing film 22, and a retardation film). 23), and the surface of the protective release film 3 is detachably attached with a sticker 5. In addition, in FIG. 8, for the sake of convenience, except for the sticker 5, a laminated optical film 1 having the same layer structure as that shown in FIG. 2 (layer structure of the first embodiment) is shown. However, the aforementioned sticker 5 may be attached to the surface of the release film for protection of the laminated optical film 1 having the layers shown in FIGS. 3 to 6. The sticker 5 includes a base material 51 and an adhesive layer 52 provided on the back surface of the base material 51. Hereinafter, in order to distinguish it from the adhesive layer 4 provided on the back surface of the protective release film 3, the adhesive layer 52 provided on the back surface of the base material 51 of the sticker 5 is referred to as a "sticker adhesive layer". In this embodiment, the sticker 5 is detachably attached to the surface of the protective release film 3 through the sticker adhesive layer 52.

<Polarizing Film> The polarizing film 22 shown in each figure is an optically anisotropic film capable of exhibiting absorption dichroism. The polarizing film has an absorption axis and a transmission axis in its plane. The polarizing film has a property of selectively transmitting linearly polarized light having a vibration direction parallel to the extending direction of the transmission axis. As the polarizing film, a conventionally well-known polarizing film can be used, and a representative example thereof is a polarizing film obtained by adsorbing and stretching a dichroic substance on a hydrophilic polymer film (hereinafter referred to as "adsorption type polarizing film"). ); A polarizing film (hereinafter referred to as a “coating-type polarizing film”) and the like obtained by applying a coating liquid containing an organic pigment on an arbitrary film and drying it. In the present invention, it is desirable to use an adsorption-type polarizing film. The hydrophilic polymer film is not particularly limited, and examples thereof include a polyvinyl alcohol (PVA) film, a partially formalized polyvinyl alcohol film, a polyethylene terephthalate (PET) film, and an ethylene- Vinyl acetate copolymer-based films, partially saponified films of such films, and the like. Among them, especially the dyeability using iodine is better, and a polyvinyl alcohol-based film is preferable. As said dichroic substance, conventionally well-known thing can be used, For example, an iodine, an organic dye, etc. are mentioned. Among them, iodine is preferable. The adsorption-type polarizing film can be obtained, for example, after swelling a hydrophilic polymer film, dyeing the film with a dichroic substance, and crosslinking and stretching the dyed film. Examples of the adsorption-type polarizing film are disclosed in Japanese Patent Laid-Open No. 2010-039154, Japanese Patent Laid-Open No. 2011-016920, Japanese Patent Laid-Open No. 2011-016922, and Japanese Patent Laid-Open No. 2011-034061. And other polarizing films. The thickness of the polarizing film is not particularly limited, and is, for example, 2 μm to 100 μm.

<Phase-Difference Film> The retardation films 23, 231, and 232 shown in the drawings are optically anisotropic films having birefringence, and are films capable of giving a predetermined retardation to transmitted light. Typical examples of the retardation film include a half-wavelength plate and a quarter-wavelength plate. As the retardation film, a conventionally well-known film can be used. Examples of the retardation film include a birefringent film containing a thermoplastic resin; an alignment film obtained by orienting and then crosslinking and polymerizing liquid crystal monomers; an alignment film of liquid crystal monomers; Films of alignment layers of liquid crystal monomers and the like. The thickness of the retardation film is not particularly limited, and is, for example, 5 μm to 100 μm. Examples of the thermoplastic resin include polyolefin resins, cycloolefin resins, polyvinyl chloride resins, cellulose resins, styrene resins, acrylonitrile-butadiene-styrene resins, and acrylonitrile-styrene resins. Resins, polymethyl methacrylate resins, polyvinyl acetate, polyvinyl chloride resins, and other general-purpose plastics; polyamide resins, polyacetal resins, polycarbonate resins, modified polyelongation resins General purpose engineering plastics such as phenyl ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, etc .; polyphenylene sulfide resin, polyfluorene resin, polyether fluorene resin Super engineering plastics such as polyether ether ketone resin, polyarylate resin, liquid crystalline resin, polyamidoimide resin, polyamidoimide resin, polytetrafluoroethylene resin, etc.

<Protective Film> The protective films 21, 211, and 212 shown in each figure are provided to protect the surface of an optically anisotropic film such as a polarizing film and a retardation film. The protective film is not particularly limited as long as it is a transparent film, and conventionally known films can be used. For example, as a protective film, an optically isotropic transparent film can be used. The protective film is not particularly limited in terms of a material, and a conventionally known resin film can be used. Examples of the material of the protective film include cellulose-based resin films such as cellulose triacetate (TAC) and cellulose acetate; Cycloolefin resin films such as olefin resins; olefin resin films such as polyethylene and polypropylene; polyester resin films; (meth) acrylic resin films and the like. In addition, in this specification, (meth) acrylfluorenyl means acrylfluorenyl and / or methacrylfluorenyl. The thickness of the protective film is not particularly limited, and is, for example, 10 μm to 120 μm, and more preferably 20 μm to 60 μm.

Moreover, you may apply surface treatment to the surface of a protective film. As the aforementioned surface treatment, a well-known treatment can be adopted. Examples of the surface treatment include an anti-glare treatment, an anti-sticking treatment, and a formation process of a hard coat layer.

<Protection release film and adhesive layer> The protection release films 3, 31, and 32 shown in each figure are provided in order to protect the surface, the surface, and the back surface of the optical film 2. Therefore, the protective release film is finally peeled and removed from the optical film. The protective release film is not particularly limited as long as it is a film capable of appropriately protecting an optical film. Usually, a resin film is used as a protective peeling film. The material of the resin film is not particularly limited, and examples thereof include polyester resins such as polyethylene terephthalate and polylactic acid; olefin resins such as polyethylene, polypropylene, and cyclic olefins; polystyrene, Polystyrene resins such as styrene-butadiene copolymers; polyamide resins; thermoplastic resins such as vinyl chloride resins; one or two or more mixtures are selected. The thickness of the protective release film is not particularly limited, and is, for example, 20 μm to 100 μm, and more preferably 20 μm to 80 μm.

The adhesive layers 4, 41, and 42 shown in the drawings are for attaching the protective release films 3, 31, and 32 to the optical film 2, and are laminated on the back surfaces of the protective release films 3, 31, and 32. The protective release film attached through the adhesive layer is peelable from the optical film surface (protective film surface). In other words, when the protective release film is peeled off, the protective release film is separated between the adhesive layer and the surface of the optical film, and the adhesive layer is peeled off. As the adhesive layers 4, 41, 42, an adhesive layer having a shear stress of 22 N / cm ² or less can be used. By attaching a protective release film through the adhesive layer, it is possible to prevent the axis of the optically anisotropic film from being shifted after the sticker attached to the protective release film is removed. Shear stress the adhesive layer is more preferably 20N / cm ² or less, more preferably 18N / cm ² or less, still more preferably 15N / cm ² or less. Although the lower limit value of the shear stress of the adhesive layer is not particularly limited, when the lower limit value is too small, the adhesive layer may become too soft, and after the protective release film is peeled from the optical film, a part of the adhesive layer may remain Optical film surface. From this viewpoint, it is more preferably 3N / cm ² or more, more preferably 5N / cm ² or more, and even more preferably 6N / cm ² or more. The shear stress of the adhesive layer can be measured using a precision universal testing machine (trade name "AUTOGRAPH" manufactured by Shimadzu Corporation). Specifically, an adhesive layer to be measured is provided on the back surface of the protective release film, and the adhesive layer is attached to the surface of the optical film so that the adhesive area becomes vertical × width = 1 cm × 1 cm, and The maximum load (N / cm ² ) when the protective peeling film was stretched parallel to the surface of the optical film at 23 ° C. and a stretching speed of 0.06 mm / min was the shear stress.

The adhesive layer is an adhesive layer that is adhered to the surface of the optical film with a peelable adhesive strength. The adhesive strength of the adhesive layer to the optical film is not particularly limited. For example, about 0.2N / 25mm to 20N / 25mm can be exemplified, and more preferably about 2N / 25mm to 15N / 25mm. Wherein, the aforementioned adhesive strength was cut in accordance with JIS Z 0237, and a protective peeling film provided with an adhesive layer was cut into a width × 100 mm × 25 mm to prepare a test piece, and the test piece was attached to the optical film through the adhesive layer. After the surface, a test piece was measured in a peel test under conditions of a peel angle of 90 degrees, a peel speed of 300 mm / min, and a temperature of 23 ° C.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited as long as it can form a pressure-sensitive adhesive layer having a shear stress of 22 N / cm ² or less, and conventionally known pressure-sensitive adhesives can be used. Examples of the adhesive include an acrylic adhesive, a polysiloxane adhesive, a polyoxyalkylene adhesive, a urethane adhesive, a rubber adhesive, a polyester adhesive, and a polyamide. Based adhesives, epoxy based adhesives, vinyl alkyl ether based adhesives, fluorine based adhesives, and the like. These adhesives can be used individually or in combination of 2 or more types. Examples of the acrylic pressure-sensitive adhesive include an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer having a monomer unit of an alkyl (meth) acrylate as a main skeleton. The average carbon number of the alkyl group of the alkyl (meth) acrylate constituting the backbone of the acrylic polymer is preferably about 1 to 18. Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethyl (meth) acrylate. Hexyl hexyl ester, isooctyl (meth) acrylate, isononyl (meth) acrylate, isododecyl (meth) acrylate, etc. These can be used in combination of one kind or two or more kinds. Among them, an alkyl (meth) acrylate having 1 to 12 carbon atoms in the alkyl group is preferred. Examples of the polysiloxane-based adhesive include peroxide-crosslinked polysiloxane-based adhesives (peroxide-hardened polysiloxane-based adhesives), and additional reaction-type polysiloxane-based adhesives. The thickness of the adhesive layer is not particularly limited, and is, for example, 2 μm to 30 μm, and more preferably 5 μm to 25 μm. In addition, the shear stress of the adhesive layer also changes depending on the surface state of the protective release film to which the adhesive layer is attached. Therefore, it is possible to select an appropriate adhesive in consideration of the material of the surface of the protective release film and the like to constitute an adhesive layer having the aforementioned shear stress.

<Sticker> The sticker 5 shown in each figure can be attached to the surface of the protective release film 3 as needed. The sticker includes various information used by the manufacturer of the laminated optical film or the manufacturer of the image display device in the manufacturing process of the product. The foregoing information may include management numbers such as product lot numbers, product specifications, and shipping destination information. The foregoing information is replaced with a display such as a number or a mark, or read by a optical device such as a bar code and a two-dimensional code, or the IC chip, etc., and is provided on a sticker. Such stickers are also called labels and the like. In the example shown in FIG. 7, various kinds of information are stored as bar codes and numbers, and the bar codes and the like are printed on the sticker 5. As shown in FIG. 8, the sticker 5 includes a base material 51 and a sticker adhesive layer 52. The sticker 5 is detachably attached to any part of the surface of the protective release film 3 through the sticker adhesive layer 52. Although the size of the sticker may be the same as the size of the protective release film, the size of the sticker is generally smaller than the size of the protective release film. In other words, the surface area of the sticker is smaller than the surface area of the protective release film. The specific size of the sticker is, for example, 縦 × width = 1cm ~ 10cm × 1cm ~ 10cm.

The base material of the sticker is not particularly limited, and a known base material can be used. Examples of the substrate include resin films, paper, synthetic paper, foamed resin films, and laminated films of these substrates. The thickness of the substrate is not particularly limited, and is, for example, 30 μm to 100 μm. Moreover, in order to attach a sticker to a protective peeling film, a sticker adhesive layer is laminated | stacked on the back surface of a base material. The sticker attached through the sticker adhesive layer is peelable from the surface of the protective release film. In other words, when the sticker is peeled off, the sticker is separated from the surface of the sticker adhesive layer and the surface of the release film for protection, and is peeled off along with the adhesive layer. The adhesive constituting the sticker adhesive layer is not particularly limited, and a conventionally known adhesive can be used. The adhesive strength of the sticker to the protective release film is not particularly limited. However, when the adhesive strength of the sticker adhesive layer is too small, the sticker may fall off, and when it is too large, the sticker may become difficult to peel off. From this point of view, the adhesive strength of the sticker to the protective release film is, for example, 1N / 25mm to 20N / 25mm, and more preferably 3N / 25mm to 15N / 25mm. The aforementioned adhesive strength was cut in accordance with JIS Z 0237, and a sticker provided with a sticker adhesive layer was cut and grown × width = 100 mm × 25 mm to produce a test piece, and the test piece was attached to the protective release film through the sticker adhesive layer. After the surface, a test piece was measured in a peel test under conditions of a peel angle of 90 degrees, a peel speed of 300 mm / min, and a temperature of 23 ° C. According to the present invention, it is possible to effectively prevent display unevenness of the laminated optical film not only when a sticker having a relatively small adhesive strength is used, but also when a sticker having a relatively strong adhesive strength is used.

[Image Display Device] The laminated optical film 1 of the present invention is used as a constituent member of, for example, an image display device. FIG. 9 is a perspective view of the image display device, FIG. 10 is a cross-sectional view thereof, and FIG. 11 is an enlarged cross-sectional view thereof. In FIGS. 9 to 11, the image display device 10 is, for example, a liquid crystal display device including a liquid crystal panel 7. As shown in FIGS. 10 and 11, the liquid crystal panel 7 includes a liquid crystal cell 71, a viewing-side polarizing plate 72 disposed on the viewing side of the liquid crystal cell 71, and a view opposite to the viewing side of the liquid crystal cell 71. Seeing side polarizing plate 73. The liquid crystal cell 71 is filled with a liquid crystal 713 between a pair of glass plates 711 and 712. The viewing-side polarizing plate 72 is a laminated optical film 1 using the present invention. That is, the viewing-side polarizing plate 72 (laminated optical film 1) has a retardation film 23, a polarizing film 22, a protective film 21, an adhesive layer 4 and a protective release film 3 in this order from the side closest to the liquid crystal cell 71. The viewing-side polarizing plate 73 includes a retardation film 733, a polarizing film 732, and a protective film 731 in this order from the side closest to the liquid crystal cell 71. The viewing-side polarizing plate 72 and the viewing-side polarizing plate 73 are bonded to the liquid crystal cell 71 through an appropriate adhesive or an adhesive (not shown). The polarizing film 732 of the viewing-side polarizing plate 73 and the polarizing film 22 of the viewing-side polarizing plate 72 are arranged so that their absorption axes are orthogonal to each other (so-called orthogonal polarization). In addition, a sticker 5 is detachably attached to the surface of the protective release film 3 of the viewing-side polarizing plate 72 (the laminated optical film 1 of the present invention) through a sticker adhesive 52. However, the viewing-side polarizing plate 73 is not attached with a protective release film. Behind the viewing-side polarizing plate 73 is a light source 81 (backlight or the like). The liquid crystal panel 7 and the light source 81 are arranged in a frame 82 having a frame 82a.

In addition, the liquid crystal panel 7 includes a color filter, an alignment film, an electrode, a spacer, an electronic circuit, and the like in addition to the polarizing plate and the liquid crystal cell, but these are not shown. In addition to the light source and the liquid crystal panel, a control device, a light guide plate, wiring, and the like are provided in the housing, but these are not shown. Furthermore, although the liquid crystal display device shown in the figure is a transmissive type in which the light source 81 is disposed on the side of the viewing surface of the liquid crystal panel 7, it is not limited thereto, and may be a reflective type or a transflective type (not shown). A reflective liquid crystal display device is a light source arranged on a viewing surface side of a liquid crystal panel or a light source arranged on a side surface of a liquid crystal panel, and a reflection plate reflects light to perform image display. The semi-transmissive liquid crystal display device has a form having both the transmissive type and the reflective type.

The sticker 5 attached to the surface of the protective release film 3 of the liquid crystal display device (the image display device 10) is, for example, peeled off by the manufacturer of the image display device before the product is shipped. The protective peeling film 3 of the liquid crystal display device (the image display device 10) is peeled off by, for example, a product purchaser. By the peeling protection release film 3, the protective film 21 of the viewing-side polarizing plate 72 (laminated optical film 1) appears. The surface of the protective film 21 becomes a screen, and an image can be viewed.

An image display device having the laminated optical film of the present invention is unlikely to cause display unevenness on a screen. I guess this is based on the following effects. As shown in FIG. 12, when the sticker is removed, the surface of the protective release film (optical film) is pulled by the sticker adhesive layer and followed. At this time, although the thickness of the protective release film does not change, there are some changes in the adhesive layer. Therefore, the internal stress of the adhesive layer remains after the sticker is removed. And this stress will act on the polarizing film or the retardation film with the passage of time, and cause these films to have an axis offset. The axis of the polarizing film and / or the retardation film is shifted to cause an unexpected light leakage from the screen of the image display device, which is a cause of uneven display. In particular, the retardation film may cause light leakage due to a slight axis shift, so the adverse effect caused by the peeling of the sticker greatly affects the laminated optical film having the retardation film. In this regard, according to the present invention, by using an adhesive layer having a shear stress of 22 N / cm ² or less, even if the adhesive layer is deformed when the sticker is peeled off, the original state can be easily and immediately restored. Layers are less prone to residual internal stress. Therefore, even after leaving the sticker for a long time, stress will not act on the optically anisotropic film such as a retardation film or a polarizing film, and the axis of the optically anisotropic film can be prevented from shifting. Therefore, by using the laminated optical film of the present invention, it is possible to provide an image display device that is less prone to display unevenness even if a sticker for management of a manufacturer is attached.

In addition, as a method of preventing uneven display of a laminated optical film having a protective peeling film with a sticker attached, the following method is also effective: (a) peeling the protective peeling film from the surface of the optical film immediately after peeling the sticker; ( b) peeling the protective release film with the sticker from the surface of the optical film; (c) peeling the sticker, and then peeling the protective release film from the surface of the optical film in less than 24 hours. This is apparent from Reference Examples 1 to 3 described below. Although these three methods can prevent display unevenness, with regard to the methods (a) and (c), after peeling off the sticker, the protective release film must be peeled off within a predetermined time, and there is a time limit. For example, when a manufacturer peels off a sticker and a purchaser peels off a protective release film, it often takes a long time between the former and the latter. Therefore, after peeling off the sticker, the protective release film may not be peeled off within a predetermined time. In addition, the method (b) described above has restrictions on the use of the sticker and the protective release film. In this regard, when an adhesive layer having a shear stress of 22 N / cm ² or less is used, it is not subject to the aforementioned time and use restrictions, and display unevenness can be prevented. In addition, it is needless to say that while using an adhesive layer having a shear stress of 22 N / cm ² or less and peeling off a sticker or the like by any of the methods (a) to (c) above, uneven display can be prevented. Examples

Hereinafter, the present invention will be further explained by showing examples and comparative examples. However, the present invention is not limited to the following examples.

[Materials used in Examples and Comparative Examples] ・ Protective release film with adhesive layer (1) A polyethylene terephthalate film with a thickness of 50 μm (trade name manufactured by Nitto Denko Corporation) RP296C "). The back surface layer of this film has an adhesive layer with a thickness of 12 μm. The adhesive layer is an acrylic adhesive.・ The protective release film (2) with an adhesive layer uses a polyethylene terephthalate film with a thickness of 50 μm (trade name "RP108C" manufactured by Nitto Denko Corporation). The back surface layer of this film has an adhesive layer with a thickness of 12 μm. The adhesive layer is an acrylic adhesive.

・ The protective film (3) uses a 60 μm-three cellulose acetate (TAC) film (trade name "TD60UL" manufactured by FUJIFILM).・ Protective film (4) A film with an anti-glare layer having a thickness of 5 μm is used on the surface of a 60 μm-three cellulose acetate (TAC) film (trade name “TD60UL” manufactured by FUJIFILM Co., Ltd.).・ Protective film (5) A film with a low reflection layer with a thickness of 6 μm is used on the surface of a 60 μm-three cellulose acetate (TAC) film (trade name “TD60UL” manufactured by FUJIFILM Corporation).・ Protective film (6) A transparent protective film with a thickness of 40 μm described in [0126] of Japanese Patent Laid-Open No. 2016-151696 is used.・ The protective film (7) uses a polyethylene terephthalate film (trade name "SRF-80" manufactured by Toyobo Co., Ltd.) with a thickness of 80 μm.

・ Adhesive (8) uses an active energy ray hardening type adhesive. This active energy ray hardening type adhesive is prepared by mixing the components in accordance with Example 1 described in Table 1 of Japanese Patent Laid-Open No. 2016-184151, and adding KAYACURE-DETX- S (2,4-Diethyl 9-oxysulfur ; Manufactured by Nippon Kayaku Co., Ltd.) 1.5 g and Irgacure 907 (2-methyl-1- (4-methylphenylthio) -2- (3) (Phenylpropan-1-one; manufactured by BASF) was prepared by stirring.・ Adhesive (9) uses an aqueous adhesive. This water-based adhesive is prepared as follows. With respect to 100 parts by weight of a polyvinyl alcohol-based resin (average degree of polymerization of 1200, degree of saponification of 98.5%, and degree of acetamidine of 5 mole%) containing 50% by weight of methyl alcohol melamine at 30 It was dissolved in pure water under a temperature condition of ° C to obtain an aqueous solution having a solid content concentration of 3.7% by weight. 18 parts by weight of an alumina colloidal aqueous solution (average particle diameter: 15 nm, solid content concentration: 10% by weight, positive charge) was added to 100 parts by weight of the aqueous solution to prepare an adhesive solution. The viscosity of the adhesive solution was 9.6 mPa · s, the pH was in the range of 4 to 4.5, and the blending amount of the alumina colloidal aqueous solution was 74 parts by weight based on 100 parts by weight of the polyvinyl alcohol resin.

・ Polarizing film with retardation film (10) A polarizing film with a thickness of 60 μm (trade name “PE6000” manufactured by KURARAY) has a retardation film with a thickness of 52 μm (product of ZEON Japan) "ZB12-50135").

・ Sticker (11) A commercially available cellophane tape (trade name "CELLOTAPE (registered trademark)" manufactured by NICHIBAN) is cut into vertical × horizontal = 20mm × 40mm, and is used as the sticker (11).・ Sticker (12) A commercially available masking tape (trade name "MASKING TAPE No. 720" manufactured by Nitto Denko Corporation) is cut into vertical × horizontal = 20mm × 40mm, and used as the sticker (12).

[Example 1] On the surface (polarizing film surface) of a polarizing film (10) with a retardation film, an MCD coater (mesh shape: honeycomb, gravure cylinder lines: 1000 lines / inch, The rotation speed is 140% / line speed), the adhesive agent (8) is applied at a thickness of 1 μm, and the back surface of the protective film (3) is bonded thereon. Then, from both sides of the laminated body after bonding, visible light was irradiated with an active energy ray irradiation device to harden the adhesive (8), followed by hot air drying at 70 ° C for 3 minutes to produce an optical film. The active energy ray irradiation device is a device that irradiates visible light (gallium-encapsulated metal halide lamp) as an active energy ray, and uses (Light HAMMER10 (bulb: V bulb, peak illumination: 1600 mW / cm, manufactured by Fusion UV Systems, Inc.) ^2. Cumulative exposure: 1000 / mJ / cm ² (wavelength: 380 ~ 440nm)) The protective release film (1) is attached to the surface of the protective film (3) of the optical film through an adhesive layer to produce A laminated optical film having a layer structure as shown in Fig. 2 was made. In addition, the size of the laminated optical film was a square having a length of 50 mm and a width of 50 mm.

[Examples 2 to 10 and Comparative Examples 1 to 5] Laminated layers were produced in the same manner as in Example 1 except that the protective release film, protective film, or adhesive having an adhesive layer was changed to that shown in Table 1. Optical film. In Table 1, the film (1) indicates the above-mentioned protective release film (1) with an adhesive layer, and the film (2) indicates the above-mentioned protective release film (2) with an adhesive layer, and the film (3) indicates the above Protective film (3), film (4) indicates the protective film (4), film (5) indicates the protective film (5), film (6) indicates the protective film (6), and film (7) indicates the protective film (7) The film (10) indicates the polarizing film (10) with a retardation film. In addition, Example (10) is an adhesive (9) using a water-based adhesive. That is, in Example (10), the adhesive (9) was dropped on the bonded portion of the polarizing film surface of the polarizing film with a retardation film and the protective film, and the two films were laminated, and then dried with hot air at 70 ° C. 4 minute.

[Measurement of Shear Stress] In each of the examples and comparative examples, in order to measure the shear stress of the adhesive layer of the protective release film, the maximum load was measured in the following procedure. The protective release film (1) with an adhesive layer used in Example 1 was cut to grow × width = 100 mm × 10 mm, and the bonding area (contact area) of the adhesive layer was 1 cm ² (1 cm on each side). (Square), after the protective release film (1) is bonded to the protective film (3), the protective release film (1) is stretched at 23 ° C and at a stretching speed of 0.06 mm / min as shown in Fig. 13 It was parallel to the surface of the protective film, and the maximum load (N / cm ² ) at that time was measured using a precision universal testing machine (trade name "AUTOGRAPH" manufactured by Shimadzu Corporation). This maximum load is the shear stress of the adhesive layer. Regarding Examples 2 to 10 and Comparative Examples 1 to 5, the protective peeling film and the protective film each having an adhesive layer were also used, and the shear stress of each adhesive layer was measured in the same manner. The results are shown in Table 1.

[Table 1]

[Production of image display device and display characteristic test] A sticker (11) was attached to a part of the surface of the release film (1) for protection of the laminated optical film of Example 1. The viewing-side polarizing plate is detached from the liquid crystal panel of the liquid crystal display device in general use, and the laminated optical film to which the aforementioned sticker (11) is attached is assembled on the viewing-side polarizing plate of the liquid crystal panel. As described above, a test liquid crystal display device as shown in FIGS. 9 to 11 was obtained. Next, the sticker (11) attached to the surface of the protective release film (1) of the liquid crystal display device was peeled off with a finger, and then left at 23 ° C and 60% RH for 24 hours. After that, the protective peeling film (1) was peeled off with a finger, the screen of the liquid crystal panel (the surface of the protective film (3)) was exposed, and the power of the liquid crystal display device was turned on to visually confirm the state of the screen. As a result, display unevenness was not observed. The laminated optical films of Examples 2 to 10 were also carried out in the same manner as in Example 1. They were assembled in a liquid crystal display device, the stickers were removed, and they were left for 24 hours. After visual inspection, the protective film was removed. Picture state. As a result, no display unevenness was observed in any of the examples. In the sixth embodiment, a sticker (12) is used instead of the sticker (11). The laminated optical films of Comparative Examples 1 to 5 were also carried out in the same manner as in Example 1. They were assembled in a liquid crystal display device, the stickers were removed, and they were left for 24 hours. Picture status. As a result, it was confirmed that, regardless of which of the comparative examples, uneven display was generated on the screen with traces like stickers. This display unevenness looks like blurry white spots. FIG. 14 is a photographic view of the periphery of a portion where a sticker is attached on the screen of Comparative Example 1. FIG.

[Reference Example 1] A liquid crystal display device for testing was produced in the same manner as in the above-mentioned [Production of an image display device], and using the laminated optical film of Example 1. After peeling off the sticker (11) attached to the surface of the protective release film (1) of the liquid crystal display device with a finger, immediately peel off the protective release film (1) with a finger to make the screen of the liquid crystal panel (the surface of the protective film) ) Is exposed, and the power of the liquid crystal display device is turned on, and the state of the screen is visually confirmed. As a result, display unevenness was not observed. Similarly, in the liquid crystal display device using the laminated optical film of Comparative Example 1, display unevenness was not observed when the protective peeling film (2) was peeled off immediately after peeling off the sticker (11).

[Reference Example 2] A test liquid crystal display device was produced in the same manner as in the above-mentioned [Production of an image display device], using the laminated optical film of Example 1. In this liquid crystal display device, a protective peeling film (1) in a state where a sticker (11) is attached is peeled off with a finger. In other words, with the sticker (11), the protective peeling film (1) was peeled off with a finger, the screen of the liquid crystal panel (the surface of the protective film) was exposed, and the power of the liquid crystal display device was turned on to visually confirm the state of the screen. As a result, display unevenness was not observed. The same applies to the liquid crystal display device using the laminated optical film of Comparative Example 1. When the protective peeling film (2) was peeled off with the sticker (11), display unevenness was not observed.

[Reference Example 3] A liquid crystal display device for testing was produced in the same manner as in the above-mentioned [Production of an image display device], and the laminated optical film of Example 1 was used. After peeling off the sticker (11) attached to the surface of the protective release film (1) of this liquid crystal display device with a finger, it was left at 23 ° C and 60% RH for 23 hours. After that, immediately peel off the protective release film (1) with a finger, expose the screen of the liquid crystal panel (the surface of the protective film (3)), and power on the liquid crystal display device to visually confirm the state of the screen. As a result, display unevenness was not observed. The same applies to the liquid crystal display device using the laminated optical film of Comparative Example 1. When the sticker (11) is peeled off and the protective peeling film (2) is peeled off immediately after being left at 23 ° C and 60% RH for 23 hours, No uneven display was observed.

1‧‧‧ laminated optical film

10‧‧‧Image display device

2‧‧‧ optical film

21,211,212,731‧‧‧Protective film

22, 732‧‧‧ polarizing film (optical anisotropic film)

23, 231, 232, 733‧‧‧ phase contrast films (optical anisotropic films)

24‧‧‧Surface treatment layer

3, 31, 32‧‧‧Protection release film

4, 41, 42‧‧‧ Adhesive layer

5‧‧‧ Sticker

51‧‧‧ substrate

52‧‧‧sticker adhesive layer

7‧‧‧ LCD unit

71‧‧‧LCD layer

711, 712‧‧‧ glass plate

713‧‧‧LCD

72‧‧‧Viewing side polarizer

73‧‧‧ Looking back side polarizer

81‧‧‧light source

82‧‧‧Frame

82a‧‧‧border

FIG. 1 is a schematic perspective view of the laminated optical film of the present invention as viewed from the surface side. However, a layer structure such as an optical film is not shown. FIG. 2 is a cross-sectional view of a laminated optical film according to the first embodiment (a cross-sectional view cut along a line II-II in FIG. 1). 3 is a cross-sectional view of a laminated optical film according to a second embodiment. 4 is a cross-sectional view of a laminated optical film according to a third embodiment. Fig. 5 is a sectional view of a laminated optical film according to a fourth embodiment. Fig. 6 is a sectional view of a laminated optical film according to a fifth embodiment. Fig. 7 is a schematic perspective view of a laminated optical film according to a sixth embodiment as viewed from the front side. However, a layer structure such as an optical film is not shown. FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 7. FIG. 9 is a schematic perspective view of the image display device of the present invention as viewed from the front side. FIG. 10 is a cross-sectional view of the image display device cut along the line X-X in FIG. 9. However, the layer structure of an optical film or the like is not shown and is not shown. FIG. 11 is an enlarged cross-sectional view of a portion XI in FIG. 10. FIG. 12 is a reference side view for explaining the function of the laminated optical film of the present invention. FIG. 13 is a reference side view showing a procedure of a method for measuring a shear stress of an adhesive layer. 14 is a photographic view of the surface of a laminated optical film of Comparative Example 1. FIG.

Claims (6)

A laminated optical film is provided with: an optical film having an optically anisotropic film; and a protective release film that is releasably attached to the surface of the optical film through an adhesive layer; and shearing the adhesive layer The stress is 22 N / cm ² or less. For example, the laminated optical film according to claim 1, wherein the shear stress of the adhesive layer is 3 N / cm ² or more. The laminated optical film according to claim 1 or 2, wherein a peelable sticker is attached to the surface of the aforementioned protective release film. The laminated optical film according to claim 1 or 2, wherein the optical film has the optical anisotropic film and a protective film laminated on a surface of the optical anisotropic film. The laminated optical film according to claim 1 or 2, wherein the optically anisotropic film contains a retardation film. An image display device having a laminated optical film as claimed in claim 1 or 2.