TWI746086B - Optical laminated body and image display device - Google Patents

Abstract

The present invention provides an optical laminate that is excellent in crack resistance even if it has a deformed processed part. The optical layered body of the present invention has a deformed processed part, and is provided with an adhesive layer, a polarizer, an adhesive layer, a brightness enhancement film, and a surface treatment layer having a thickness of 2.5 μm or less in this order.

Description

Optical laminated body and image display device

Field of invention

The present invention relates to an optical laminate and an image display device. In more detail, it relates to an optical laminate having portions (for example, cutouts, openings) that have undergone special-shaped processing, and an image display device including the optical laminate.

Background of the invention

Optical laminates such as polarizers are used in various image display devices such as mobile phones and notebook personal computers (PCs). Depending on the application, the optical layered body can be subjected to irregular processing such as notches and openings. For example, it is known that in an image display device equipped with a camera, an opening is formed in a portion corresponding to the camera (Patent Document 1). However, there is a problem that by performing special-shaped processing on the optical layered body, stress concentration occurs in the special-shaped processed portion, and cracks are likely to occur.

Various optical films are used for the optical laminate according to the application. For example, a brightness enhancement film is used for the purpose of increasing the brightness of an image display device. The brightness enhancement film is composed of a stretched film or a liquid crystal layer, and is a mechanically fragile film. Therefore, in the optical laminate including the brightness-enhancing film, there is a problem that the problem of cracks caused by the deformed processing becomes more significant. Advanced technical literature Patent literature

Patent Document 1: Japanese Patent Application Publication No. 2014-112238

Summary of the invention The problem to be solved by the invention

The present invention has been accomplished in order to solve the above-mentioned conventional problems, and its main object is to provide an optical laminate that is excellent in crack resistance even if it has a deformed processed portion. way of solving the problem

The optical laminate of the present invention has a special-shaped processed part, and is provided with an adhesive layer, a polarizer, an adhesive layer, a brightness enhancement film, and a surface treatment layer having a thickness of 2.5 μm or less in this order. In one embodiment, the thickness of the adhesive layer is 20 μm or less. In one embodiment, the surface treatment layer is a hard coat layer. In one embodiment, the thickness of the above-mentioned polarizer is 30 μm or less. In another aspect of the present invention, there is provided an image display device including the above-mentioned optical laminate. Invention effect

According to the present invention, it is possible to provide an optical laminate having excellent crack resistance even if it has a deformed processed portion. The optical laminate of the present invention has a special-shaped processed part, and is provided with an adhesive layer, a polarizer, an adhesive layer, a brightness enhancement film, and a surface treatment layer having a thickness of 2.5 μm or less in this order. For optical laminates that have undergone special-shaped processing, stress concentration occurs in the special-shaped processed portion, and thin film bending stress is locally generated. Therefore, in particular, there is a tendency for cracks to be easily generated in the brightness-enhancing film. By reducing the thickness of the surface treatment layer (more specifically, to less than 2.5 μm), the bending moment can be reduced, and the bending stress applied to the brightness enhancement film can be alleviated. Therefore, the crack resistance of the optical laminate can be improved.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Optical laminate Fig. 1 is a schematic cross-sectional view of an optical laminate according to an embodiment of the present invention. The optical laminate 100 illustrated in the figure is provided with an adhesive layer 10, a polarizer 20, an adhesive layer 30, a brightness enhancement film 40, and a surface treatment layer 50 having a thickness of 2.5 μm or less in this order. By setting the thickness of the surface treatment layer 50 to be 2.5 μm or less, the bending stress applied to the brightness enhancement film is alleviated, and it is possible to provide an optical laminate having excellent crack resistance even in the case of a deformed processed portion. As the surface treatment layer, for example, a hard coat layer, an anti-reflection layer, an anti-glare layer (antiglare layer), and the like can be cited. The surface treatment layer is preferably a hard coat layer. In addition, although not shown, in addition to the above-mentioned adhesive layer 10, polarizer 20, adhesive layer 30, brightness enhancement film 40, and surface treatment layer 50, any appropriate other layers may be further provided. Examples of other layers include protective layers such as polarizers. In addition, in actual use, in order to properly protect the adhesive layer 10, the separator is temporarily attached in a peelable manner until it is used.

Fig. 2 is a schematic plan view of an optical laminate according to an embodiment of the present invention. The optical layered body of the present invention has any suitable special-shaped processed part corresponding to its use and the like. For example, the special-shaped processed part 11 (FIG. 2(a)) of the circular opening part (through hole) as shown in the example, the special-shaped processed part 11 (FIG. 2(b)) of a cut part (notch), etc. are mentioned. In the example shown in the figure, only one special-shaped processed part is formed, but if necessary, two or more special-shaped processed parts may be formed. In addition, as described later, the shape of the optical layered body itself may be a special shape, that is, the entire outer edge of the optical layered body may be a special-shaped processed part.

The optical laminate 100 can be designed in any appropriate shape according to the application to be used and the like. In one embodiment, the processing may be performed so that the shape of the optical layered body itself becomes a different shape. Examples of the shape of the optical layered body 100 include rectangular, circular, rhombic, and irregular shapes.

Fig. 3 is a schematic plan view of an optical laminate according to another embodiment of the present invention. The optical laminate 100 illustrated in the figure can be suitably used for an instrument panel of an automobile. The optical layered body 100 has a first display unit 60 and a second display unit 70 arranged continuously, and through holes 61 and 71 for fixing various meter needles are respectively formed in the vicinity of the center of each display unit. The diameter of the through hole is, for example, 0.5 mm to 100 mm. The outer edges of the display parts 60 and 70 are formed in an arc shape along the rotation direction of the meter hand.

The deformed part can be formed by any appropriate method. Examples include cutting processing using punching knives such as Thomson knife and pinnacle knife, shafts, etc., processing using cutting knives, lasers, and the like. The processing conditions at the time of forming the deformed processed part can be set to arbitrary appropriate conditions according to the forming method used, the thickness of each layer, and the like.

Hereinafter, the adhesive layer 10, the polarizer 20, the adhesive layer 30, the brightness enhancement film 40, and the surface treatment layer 50 will be described in detail.

B. Adhesive layer The thickness of the adhesive layer 10 can be set to any appropriate thickness. For example, it is about 1 micrometer to 100 micrometers, preferably 2 micrometers to 50 micrometers, more preferably 2 micrometers to 40 micrometers, and even more preferably 5 micrometers to 35 micrometers.

The adhesive layer 10 can be formed using any appropriate adhesive. Examples of adhesives include rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, and polysiloxane adhesives. Vinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, etc. It is preferable to use an adhesive that is excellent in optical transparency, shows appropriate adhesive properties such as wettability, cohesiveness, and adhesiveness, and is excellent in weather resistance and heat resistance. Specifically, it is preferable to use an acrylic adhesive.

The adhesive layer can be formed by any appropriate method. For example, a method of applying the above-mentioned adhesive to a separation member that has undergone a peeling treatment and drying, thereby removing the polymerization solvent, etc., forming an adhesive layer, and then performing transfer; or applying the above-mentioned adhesive and drying, Thereby, the polymerization solvent and the like are removed, and the adhesive layer is formed on the polarizer. As a separator that has undergone a release treatment, a silicone release liner is preferably used. In addition, when applying the adhesive, if necessary, one or more solvents other than the polymerization solvent may be further added.

As the formation method (coating method) of the adhesive layer, any appropriate method can be used. Specifically, examples include: roll coating, roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, blade coating, and air knife coating. , Flow coating method, die lip coating method, extrusion coating method using die coater, etc.

As a method of drying the adhesive, any appropriate method can be used according to the purpose. It is preferable to use a method of heating and drying. The heating and drying temperature is preferably 40°C to 200°C, more preferably 50°C to 180°C, and even more preferably 70°C to 170°C. By setting the heating temperature in the above-mentioned range, an adhesive layer having excellent adhesive properties can be formed. Any appropriate time can be adopted for the drying time. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and even more preferably 10 seconds to 5 minutes.

The adhesive layer 10 may be protected with a sheet (separator) that has undergone a peeling treatment before being put into actual use. As the constituent material of the separator, any appropriate material can be used, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, polyester film, and porous materials such as paper, cloth, and non-woven fabrics. , Nets, foamed sheets, metal foils, and their laminates and other sheets. From the viewpoint of excellent surface smoothness, a plastic film is preferred.

As the plastic film, any film that can protect the adhesive layer is sufficient. Examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, and polyvinyl chloride film. , Vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.

The thickness of the separator can be set to any appropriate thickness. The thickness of the separator is usually 5 μm to 200 μm, preferably 5 μm to 100 μm. You can also use silicone, fluorine, long-chain alkyl or fatty acid amine-based mold release agents, silica powder, etc., to demould and antifoul the separated parts, and to coat the separated parts Anti-static treatment of type, mixed type, vapor deposition type, etc. By applying peeling treatments such as silicone treatment, long-chain alkyl treatment, and fluorine treatment to the surface of the separator, the peelability from the adhesive layer can be improved.

C. Polarizing parts Typically, the polarizer is composed of a resin film containing a dichroic substance. As the resin film, any appropriate resin film that can be used as a polarizer can be used. Typically, the resin film is a polyvinyl alcohol-based resin (hereinafter referred to as "PVA-based resin") film.

As the PVA-based resin forming the above-mentioned PVA-based resin film, any appropriate resin can be adopted. For example, polyvinyl alcohol and ethylene-vinyl alcohol copolymers can be cited. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying an ethylene-vinyl acetate copolymer. The degree of saponification of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. The degree of saponification can be determined in accordance with JIS K 6726-1994. By using a PVA-based resin with such a degree of saponification, a polarizer excellent in durability can be obtained. If the saponification is too high, there is a risk of gelation.

The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose, and the average degree of polymerization is usually 1,000 to 10,000, preferably 1,200 to 4,500, and more preferably 1,500 to 4,300. In addition, the average degree of polymerization can be determined in accordance with JIS K 6726-1994.

Examples of the dichroic substance contained in the resin film include iodine and organic dyes. These can be used alone or in combination of two or more kinds. Preferably, iodine is used.

The resin film may be a single-layer resin film or a laminate of two or more layers.

Specific examples of the polarizer composed of a single-layer resin film include a polarizer obtained by subjecting a PVA-based resin film to a dyeing process using iodine and a stretching process (typically uniaxial stretching). The above-mentioned dyeing with iodine is performed, for example, by immersing a PVA-based resin film in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing, or it can be performed while dyeing. In addition, dyeing may be performed after stretching. The PVA-based resin film can be subjected to swelling treatment, cross-linking treatment, cleaning treatment, drying treatment, etc. as needed. For example, by immersing the PVA-based resin film in water for washing before dyeing, not only can the dirt and anti-blocking agent on the surface of the PVA-based resin film be washed away, but also the PVA-based resin film can be swelled to prevent uneven dyeing.

As a specific example of a polarizer obtained using a laminate, a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate formed on the resin substrate and coating A polarizer obtained by a laminate of PVA-based resin layers of a resin base material. A polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate can be produced by the following method: for example, a PVA-based resin solution is applied to the resin substrate, dried, and then A PVA-based resin layer is formed on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; the laminate is stretched and dyed, and the PVA-based resin layer is made into a polarizer. In the present embodiment, stretching typically includes stretching the laminate by immersing in an aqueous boric acid solution. In addition, the stretching may further include in-air stretching of the laminate at a high temperature (for example, 95°C or higher) before stretching in an aqueous boric acid solution, as necessary. The obtained resin substrate/polarizer laminate can be used directly (that is, the resin substrate can be made into a protective film for the polarizer), or the resin substrate can be peeled off from the resin substrate/polarizer laminate. Any appropriate protective film suitable for the purpose is laminated on the peeling surface and used. The details of the manufacturing method of such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. The entire description of this publication can be cited in this specification as a reference.

The polarizer preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The single transmittance of the polarizer is preferably 43.0% to 46.0%, and more preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

The thickness of the polarizer can be set to any appropriate value. Typically, the thickness is 0.5 μm or more and 80 μm or less, preferably 30 μm or less, more preferably 25 μm or less, still more preferably 18 μm or less, particularly preferably 12 μm or less, and even more preferably less than 8 μm. The thickness of the polarizer is preferably 1 μm or more.

D. Subsequent layer The subsequent layer is composed of an adhesive or an adhesive. As the adhesive or adhesive, any appropriate adhesive or adhesive can be used. Examples of adhesives include rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, and polysiloxane adhesives. Vinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, etc. It is preferable to use an adhesive that is excellent in optical transparency, shows appropriate adhesive properties such as wettability, cohesiveness, and adhesiveness, and is excellent in weather resistance and heat resistance. Specifically, it is preferable to use an acrylic adhesive.

As the adhesive, any appropriate adhesive can be used as long as it is optically transparent. For example, various types of adhesives such as solvent-based, hot-melt-based, and active energy ray hardening type can be used. It is preferable to use an active energy ray-curable adhesive.

The thickness of the subsequent layer is preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 12 μm or less. The thickness of the subsequent layer is preferably 2 μm or more. By setting the thickness of the adhesive layer within such a range, it is possible to maintain the laminated state of the polarizer and the brightness enhancement film well. In addition, the bending stress applied to the brightness enhancement film can be further alleviated.

The details of the adhesive constituting such an adhesive layer are disclosed in, for example, Japanese Patent Application Laid-Open No. 2008-46147. The entire description of this gazette is used as a reference in this specification.

E. Brightness-enhancing film The brightness enhancement film is a film that separates polarized light to achieve brightness enhancement, and may be a linearly polarized light separation type or a circularly polarized light separation type. As the brightness improving film, a film composed of a stretched film, a film composed of a liquid crystal layer, and the like can be cited. The brightness enhancement film has the following function: when natural light (such as light from the backlight of an image display device) is incident, the light is separated into two polarization components, and linearly polarized light with a predetermined polarization axis or circularly polarized light with a predetermined direction is transmitted. And the function of reflecting the opaque polarized light. By passing the opaque polarized light through a reflecting plate or the like, the light after the polarization is eliminated and then incident on the brightness enhancement film, so that the utilization efficiency of the predetermined polarized light can be improved. Hereinafter, as an example, a linearly polarized light separation type brightness improving film (reflective polarizer) will be described.

The linearly polarized light separation type brightness enhancement film has the function of separating incident light into two orthogonal polarization components, transmitting one polarization component, and reflecting the other polarization component. Fig. 4 is a schematic perspective view of an example of a linearly polarized light separation type brightness enhancement film. The linearly polarized light separation type brightness enhancement film illustrated in the figure is a multilayer laminate in which a layer A having birefringence and a layer B having substantially no birefringence are alternately laminated. The total number of layers of such a multilayer laminate may be 50 to 1,000, for example. In the illustrated example, the refractive index nx in the x-axis direction of the A layer is greater than the refractive index ny in the y-axis direction, and the refractive index nx in the x-axis direction of the B layer and the refractive index ny in the y-axis direction are substantially the same. Therefore, the refractive index difference between the A layer and the B layer is large in the x-axis direction, and is substantially zero in the y-axis direction. As a result, the x-axis direction becomes the reflection axis, and the y-axis direction becomes the transmission axis. The refractive index difference between the A layer and the B layer in the x-axis direction is preferably 0.2 to 0.3. In addition, the x-axis direction corresponds to the stretching direction of the brightness enhancement film.

The layer A is preferably made of a material that exhibits birefringence by stretching. Representative examples of such materials include polyethylene naphthalate (for example, polyethylene naphthalate), polycarbonate, and acrylic resins (for example, polymethyl methacrylate), and polyethylene naphthalate is preferred. Glycol esters. The layer B is preferably composed of a material that does not substantially exhibit birefringence even if it is stretched. As a representative example of such a material, a copolyester of naphthalenedicarboxylic acid and terephthalic acid can be cited.

The linearly polarized light separation type brightness enhancement film transmits light having a first polarization direction (such as p-wave) at the interface between the A layer and the B layer, and transmits light having a second polarization direction orthogonal to the first polarization direction (such as s Wave) reflection. As for the reflected light, at the interface between the A layer and the B layer, a part is transmitted as light having a first polarization direction, and part is reflected as light having a second polarization direction. Such reflection and transmission are repeated many times in the interior of the brightness enhancement film, so that the light utilization efficiency can be improved.

In one embodiment, the linearly polarized light separation type brightness enhancement film may include a reflective layer R as the outermost layer on the opposite side of the polarizer as shown in FIG. 4. By providing the reflective layer R, the light that has not been used and returned to the outermost part of the brightness enhancement film can finally be further used, and therefore, the light use efficiency can be further improved. Representatively, the reflective layer R exhibits a reflective function through a multilayer structure of a polyester resin layer.

Typically, the linearly polarized light separation type brightness-enhancing film can be produced by combining co-extrusion and lateral stretching. Coextrusion can be performed in any suitable manner. For example, it may be a feed block method or a multi-manifold method. For example, in the feed block, the material constituting the A layer and the material constituting the B layer are extruded, and then a multiplier is used to perform multilayering. Furthermore, such a multilayered device is well known to those having ordinary knowledge in this technical field. Next, representatively, the obtained long-length multilayer laminate is stretched in a direction (TD) orthogonal to the conveying direction. For the material constituting the A layer (for example, polyethylene naphthalate), the refractive index only in the stretching direction is increased by this lateral stretching, and as a result, birefringence is exhibited. For the material constituting the B layer (for example, a copolyester of naphthalenedicarboxylic acid and terephthalic acid), the refractive index does not increase in any direction by this transverse stretching. As a result, a brightness-enhancing film (reflective polarizer) having a reflection axis in the stretching direction (TD) and a transmission axis in the conveying direction (MD) can be obtained (TD corresponds to the x-axis direction in FIG. 4, and MD and y-axis Corresponding direction). Furthermore, the stretching operation can be performed using any appropriate device.

As the brightness-enhancing film, for example, the brightness-enhancing film described in JP 9-507308 A can be used. The brightness-enhancing film may be used as it is, or it may be used after performing secondary processing (for example, stretching) on the commercial product. As a commercially available product, for example, a brand name APCF manufactured by Nitto Denko Co., Ltd., a brand name DBEF manufactured by 3M Corporation, and a brand name APF manufactured by 3M Corporation can be cited.

F. Surface treatment layer For the surface treatment layer 50, any appropriate surface treatment layer can be formed according to the use of the optical laminate. The thickness of the surface treatment layer is 2.5 μm or less, preferably 2 μm or less, more preferably 1.5 μm or less, and the thickness of the surface treatment layer is preferably 0.5 μm or more. By setting the thickness of the surface treatment layer in the above-mentioned range, even in the case of performing special-shaped processing, the bending moment to the optical laminate can be reduced. Therefore, the bending stress to the brightness enhancement film contained in the optical laminate can be alleviated, and the crack resistance of the optical laminate (more specifically, the crack resistance of the brightness enhancement film) can be improved.

As the surface treatment layer, for example, a hard coat layer, an anti-reflection layer, an anti-glare layer (antiglare layer), and the like can be cited. Preferably, the surface treatment layer is a hard coat layer. The hard coat layer is a layer with high hardness, so it can generate greater bending stress. By setting the thickness of the surface treatment layer to 2.5 μm or less, even when the surface treatment layer is a hard coat layer, the crack resistance of the optical laminate can be improved. In addition, the crack resistance of the surface treatment layer itself can also be improved.

The hard coat layer is preferably a hardened layer of any suitable ultraviolet curable resin. Examples of ultraviolet curable resins include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. If necessary, the hard coat layer may contain any appropriate additives. As a representative example of the additive, inorganic fine particles and/or organic fine particles can be cited. By containing fine particles, for example, an appropriate refractive index can be provided.

Typically, the hard coat layer can be applied to the optical laminate in a state where the base material is subjected to a hard coat treatment in advance to form a laminate. Any appropriate resin film can be used as the substrate. Representative examples of the resin constituting the resin film include polyester resins, cellulose resins, polycarbonate resins, and (meth)acrylic resins. In addition, in this specification, "(meth)acrylic resin" means acrylic resin and/or methacrylic resin.

G. Other layers The optical laminate may contain any appropriate other layers in addition to the above-mentioned adhesive layer, polarizer, adhesive layer, brightness enhancement film, and surface treatment layer. For example, a protective layer can be mentioned. Examples of materials for forming the protective layer include cellulose resins such as cellulose diacetate and cellulose triacetate, (meth)acrylic resins, cycloolefin resins, olefin resins such as polypropylene, and polyterephthalene resins. Ester resins such as ethylene formate resins, polyamide resins, polycarbonate resins, copolymer resins thereof, and the like.

The thickness of the protective layer is preferably 10 μm to 100 μm. Typically, the protective film is laminated on the polarizer via an arbitrary adhesive layer (specifically, an adhesive layer and an adhesive layer). The adhesive layer is typically formed of a PVA-based adhesive or an activated energy ray curable adhesive. The adhesive layer is typically formed of an acrylic adhesive.

H. Video display device The image display device of the present invention includes the above-mentioned optical laminate. Examples of image display devices include liquid crystal display devices and organic EL elements. In the image display device, it is preferable to arrange the optical laminate on the backlight side. As described above, the optical layered body of the present invention has excellent crack resistance even when subjected to deformed processing. Therefore, it can also be suitably used for an image display device having an abnormal-shaped image display unit represented by automobile instrument panels and smart watches. Example

Hereinafter, the present invention will be specifically described through examples, but the present invention is not limited by these examples.

[Production example 1] Production of polarizer As the substrate, an amorphous isophthalic acid copolymer polyethylene terephthalate (IPA copolymer PET) film with a water absorption of 0.75% and a Tg of 75°C was used (thickness: 100μm) . Perform corona treatment on one side of the substrate, and coat the corona-treated surface at 25°C at a ratio of 9:1 containing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetic acid modified Aqueous PVA (polymerization degree 1200, acetacetic acid modification degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z200") and dried to form a thickness of 11μm The PVA-based resin layer is made into a laminate. The obtained laminate was subjected to uniaxial stretching (air-assisted stretching) in the longitudinal direction (length direction) to 2.0 times in the longitudinal direction (length direction) in an oven at 120° C. between rolls with different peripheral speeds. Next, the layered body was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 30°C for 30 seconds (insolubilization treatment). Next, it was immersed in a dyeing bath with a liquid temperature of 30°C while adjusting the iodine concentration and the immersion time so that the polarizing plate reached a predetermined transmittance. In this example, it was immersed in an iodine aqueous solution obtained by mixing 0.2 parts by weight of iodine and 1.5 parts by weight of potassium iodide with respect to 100 parts by weight of water for 60 seconds (dyeing treatment). Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water with a liquid temperature of 30°C) for 30 seconds (crosslinking treatment). Then, the layered body was immersed in a boric acid aqueous solution (an aqueous solution obtained by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70°C while moving between rolls with different peripheral speeds. Uniaxial stretching (stretching in aqueous solution) was performed in the longitudinal direction (length direction) so that the total stretching ratio reached 5.5 times. Then, the layered body was immersed in a cleaning bath (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 30°C (washing treatment). Next, an ultraviolet curable adhesive was applied to the surface of the PVA-based resin layer of the laminate so that the thickness of the cured adhesive layer became 0.5 μm, and a protective film (thickness 20 μm, TAC film) was bonded. Next, ultraviolet rays as active energy rays were irradiated to harden the adhesive to obtain a polarizing plate (polarizer (transmittance 42.3%, thickness 5 μm)/protective film) having a total thickness of 25.5 μm.

[Manufacturing Example 2] Preparation of Adhesive Layer Forming Composition In a 4-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a condenser, 91 parts of butyl acrylate, 6 parts of N-acrylomorpholine, 2.7 parts of acrylic acid, and 0.3 parts of 2-hydroxybutyl acrylate were added as The polymerization initiator was 0.1 parts by weight of 2,2'-azobisisobutyronitrile and 200 parts by weight of ethyl acetate. Nitrogen gas was introduced while stirring slowly, and nitrogen substitution was performed. Next, the polymerization reaction was performed for 8 hours while maintaining the liquid temperature in the flask at around 55°C to prepare an acrylic polymer solution. The weight average molecular weight of the acrylic polymer was 2.2 million.

[Manufacturing Example 3] Preparation of hard coat layer forming composition 0.5% by weight of a leveling agent was added to the acrylic resin raw material (manufactured by Dainippon Printing Ink Co., Ltd., trade name: GRANDIC PC1071), and further diluted with ethyl acetate so that the solid content concentration became 50% by weight, to prepare A coating solution for hard coat formation. Furthermore, the leveling agent is based on a molar ratio of dimethylsiloxane: hydroxypropylsiloxane: 6-isocyanatohexyl isocyanurate: aliphatic polyester = 6.3:1.0:2.2:1.0 Copolymer made by copolymerization.

[Manufacturing Example 4] Preparation of adhesive composition In a 4-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a condenser, 100 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid, 0.1 parts by weight of 2-hydroxybutyl acrylate, and 2,2 as a polymerization initiator were added. 0.1 parts by weight of'-azobisisobutyronitrile and 200 parts by weight of ethyl acetate, nitrogen was introduced while slowly stirring, and nitrogen substitution was performed. Next, the liquid temperature in the flask was maintained at around 55°C, and the polymerization reaction was performed for 8 hours to prepare an acrylic polymer solution. The weight average molecular weight of the acrylic polymer was 1.92 million. With respect to 100 parts of the solid content of the obtained acrylic polymer solution, a polyisocyanate-based crosslinking agent composed of trimethylolpropane adducts of toluene diisocyanate (Japan polyurethane 0.6 parts by weight of Coronate L) manufactured by Ester Industries Co., Ltd., and an acrylic adhesive solution was prepared.

[Example 1] The adhesive composition obtained in Production Example 4 was applied to a polysiloxane-treated polyethylene terephthalate (PET) film (Mitsubishi Chemical Polyester One side of the film (strand), thickness: 38 μm) was dried at 130°C for 3 minutes to form an adhesive layer. The formed adhesive layer was transferred to the polarizer-side surface of the polarizing plate obtained in Manufacturing Example 1. On the brightness enhancement film (manufactured by 3M, product name "APF V4", thickness: 16 μm), the hard coat forming composition obtained in Manufacturing Example 3 was applied so that the thickness after drying reached 0.5 μm to form a hard coat Floor. The surface of the protective film side of the polarizing plate after the adhesive layer is formed, and the surface of the brightness enhancement film after the hard coat layer is formed. Then, the composition was formed into layers and bonded together to obtain a laminate. _{Endmill processing is performed on the obtained laminated body, and a curvature radius R 1} of 2.5 mm, a length W ₁ of 5 mm, and a maximum depth D as shown in the lower part (inverted U-shaped portion) of Fig. 5 are formed on the laminated body. With a notch of 6.5 mm, an optical laminate with a special-shaped processed part was obtained. Furthermore, the absorption axis of the polarizer was made parallel to the long side L of the optical laminate.

[Examples 2~8] Except that the hard-coat layer forming composition was coated so that the thickness of the hard-coat layer reached the thickness described in Table 1, it carried out similarly to Example 1, and obtained the optical laminated body which has a deformed processed part.

(Comparative example 1~2) Except that the hard-coat layer forming composition was coated so that the thickness of the hard-coat layer reached the thickness described in Table 1, it carried out similarly to Example 1, and obtained the optical laminated body which has a deformed processed part.

Using the optical laminates obtained in Examples 1 to 8 and Comparative Examples 1 to 2, the following evaluations were performed, and the results are shown in Table 1. (Crack resistance evaluation) Using the optical laminates obtained in the examples and comparative examples, a heating cycle test was performed 100 times in a thermal shock device (manufactured by Espec, product name: TSA-303EL-W). The heating cycle is a cycle of heating from -40°C to 85°C in 30 minutes, and cooling to -40°C in 30 minutes when the temperature in the chamber reaches 85°C, as one cycle. The presence or absence of cracks in the deformed part after 100 cycles of the heating cycle test was visually confirmed, and when the cracks were confirmed, the length of the cracks was measured using an optical microscope. When multiple cracks can be confirmed, the length of the largest crack is defined as the crack length. The respective optical laminates were evaluated according to the following criteria. 5: All layers in the optical laminate have no cracks 4: Any layer in the optical laminate has a crack less than 100μm 3: Any layer in the optical laminate has a crack of 100μm or more and less than 200μm 2: Any layer in the optical laminate has a crack of 200 μm or more and less than 300 μm 1: Any layer in the optical laminate has cracks exceeding 300μm

[Table 1]

In the optical layered bodies of Examples 1 to 8, it was confirmed that the optical layered bodies had no cracks even after the heating cycle test of 100 cycles and were excellent in crack resistance. Industrial availability

The optical laminate of the present invention can be suitably used for image display devices such as liquid crystal display devices and organic EL elements. The optical laminate of the present invention can also be suitably used for an image display device having a special-shaped image display unit represented by automobile instrument panels and smart watches.

10: Adhesive layer 11: Special-shaped processing department 20: Polarizing parts 30: Next layer 40: Brightness-enhancing film 50: Surface treatment layer 60, 70: Display 61, 71: Through hole 100: Optical laminate

Fig. 1 is a schematic cross-sectional view of an optical laminate according to an embodiment of the present invention. Fig. 2 is a schematic plan view of an optical laminate according to an embodiment of the present invention, Fig. 2(a) is a schematic plan view of an optical laminate having a circular opening as a special-shaped processed part, and Fig. 2(b) is a schematic plan view of an optical laminate having a cut-out part as a special-shaped A schematic plan view of the optical laminate of the processing part. Fig. 3 is a schematic plan view of an optical laminate according to another embodiment of the present invention. Fig. 4 is a schematic perspective view of an example of a linearly polarized light separation type brightness enhancement film that can be used in the optical laminate of the present invention. Fig. 5 is a schematic plan view illustrating a deformed processed part of an optical laminate having a deformed processed part produced in an example.

10: Adhesive layer

20: Polarizing parts

30: Next layer

40: Brightness-enhancing film

50: Surface treatment layer

100: Optical laminate

Claims (6)

An optical laminated body has a special-shaped processing part, and is provided with an adhesive layer, a polarizer, an adhesive layer, a brightness enhancement film, and a surface treatment layer with a thickness of 2.5 μm or less in this order. The optical laminate of claim 1, wherein the thickness of the adhesive layer is 20 μm or less. The optical laminate of claim 1 or 2, wherein the aforementioned surface treatment layer is a hard coat layer. The optical laminate of claim 1 or 2, wherein the thickness of the aforementioned polarizing member is 30 μm or less. The optical laminate of claim 3, wherein the thickness of the aforementioned polarizing member is 30 μm or less. An image display device comprising the optical laminate according to any one of claims 1 to 5.

Images