KR102575467B1 - Optical laminates, polarizing films and image display devices - Google Patents

Abstract

The present invention is an optical laminate in which a polarizer is bonded to a substrate containing an ionic component through an adhesive layer, wherein the substrate elutes the ionic component to the adhesive layer side, and between the polarizer and the substrate, It has a transparent block layer that suppresses migration of ionic components to the polarizer side. The optical laminate of the present invention can suppress degradation of optical properties even under a high temperature and high humidity environment.

Description

Optical laminates, polarizing films and image display devices

The present invention relates to an optical laminate in which a polarizer is bonded through an adhesive layer. Additionally, the present invention relates to a polarizing film used in the optical laminated body. The optical laminate can be used alone or in combination with other optical films to form image display devices such as liquid crystal displays (LCDs) and organic EL displays.

In a liquid crystal display device, it is essential to dispose a polarizing film on both sides of the glass substrate forming the liquid crystal panel surface due to its image forming method. Polarizing films are generally used by bonding a protective film to one or both sides of a polarizer made of a polyvinyl alcohol-based film and a dichroic material such as iodine using a polyvinyl alcohol-based adhesive or the like.

Additionally, polarizing films are exposed to harsh environments depending on their intended use or usage conditions. Therefore, polarizing films are required to be durable enough to maintain optical properties even under harsh environments. For example, it has been proposed to provide a urethane resin having a predetermined storage modulus on at least one side of the polarizer (Patent Documents 1 and 2). According to Patent Documents 1 and 2, it is described that the direct transmittance of a polarizing film can be maintained even under high temperatures.

Japanese Patent Publication No. 11-030715 Japanese Patent Publication No. 11-183726

The polarizing film may be used not only under a high temperature environment but also under a high temperature and high humidity environment. Additionally, the polarizer or polarizing film is used as an optical laminate laminated on a glass substrate or the like through an adhesive layer. However, it has been found that, depending on the glass substrate, components such as ions that become impurities may elute, for example, when maintained in a high-temperature, high-humidity environment. It was found that the eluted component migrates into the adhesive layer and enters the polarizer, thereby increasing the moisture content of the polarizer. As a result, the degree of polarization of the polarizer decreases, and the optical properties of the optical laminate decrease significantly. However, the deterioration of the optical properties of the optical laminate could not be sufficiently suppressed by providing the polarizer with a urethane resin such as those in Patent Documents 1 and 2.

The purpose of the present invention is to provide an optical laminate capable of suppressing deterioration of optical properties even under a high temperature and high humidity environment. Another object of the present invention is to provide a polarizing film for use in the optical laminated body.

Additionally, the present invention aims to provide an image display device having the above-mentioned optical laminated body.

As a result of intensive study, the present inventors discovered that the above-described problem could be solved by the following optical laminate, etc., and arrived at the present invention.

That is, the present invention is an optical laminate in which a polarizer is bonded to a substrate containing an ionic component through an adhesive layer,

The substrate is to elute ionic components to the adhesive layer side,

It relates to an optical laminate characterized by having a transparent block layer between the polarizer and the substrate that suppresses migration of the ionic component to the polarizer side.

In the optical laminate, the substrate may be an alkali glass substrate.

In the optical laminate, the present invention is preferably applied when the amount of sodium ions detected from the water used for boiling the substrate when boiling it in hot water at 120°C for 1 hour is 0.1 μg/g or more.

In the optical laminate, the transparent block layer may be formed directly on the polarizer or the substrate.

In the optical laminate, it is preferable that the thickness of the polarizer is 10 μm or less.

In the optical laminate, it is preferable that the thickness of the transparent block layer is 3 μm or less.

In the optical laminate, a cured product containing a urethane prepolymer, which is a reaction product of an isocyanate compound and a polyhydric alcohol, can be used as the transparent block layer. As the isocyanate compound, it is preferable to use at least one type selected from tolylene diisocyanate and diphenylmethane diisocyanate.

In the optical laminate, a protective film may be provided on one side of the polarizer opposite to the side having the transparent block layer.

In addition, the present invention is a polarizing film used in the optical laminate,

It relates to a polarizing film characterized by having a polarizer and a transparent block layer formed directly on the polarizer.

Additionally, the present invention relates to an image display device having the above optical laminate.

The polarizer can be used as an optical laminate bonded to various substrates through an adhesive layer, but as described above, depending on the substrate, it is thought that components such as ions that become impurities may elute in a high-temperature, high-humidity environment. And it is thought that the eluted component penetrates into the polarizer and significantly deteriorates the optical properties of the optical laminate.

The optical laminate of the present invention has a transparent block layer between the polarizer and the substrate that suppresses migration of the eluted component to the polarizer side. The transparent block layer can prevent components eluted from the substrate from transferring to the polarizer. Therefore, even in a high-temperature, high-humidity environment, the migration of eluted components that may cause deterioration of the optical properties of the polarizer to the polarizer can be prevented, thereby suppressing the deterioration of the optical properties.

1 is an example of a schematic cross-sectional view of the optical laminate of the present invention.
Figure 2 is an example of a schematic cross-sectional view of the optical laminate of the present invention.
Figure 3 is an example of a schematic cross-sectional view of the optical laminate of the present invention.
Figure 4 is an example of a schematic cross-sectional view of the optical laminate of the present invention.

The optical laminate of the present invention will be described below with reference to FIGS. 1 to 4.

In the optical laminate of the present invention, as shown in FIGS. 1 to 4, a polarizer (P) is bonded to a substrate (2) through an adhesive layer (3), and between the polarizer (P) and the substrate (2) It has a transparent block layer (1). The transparent block layer 1 can be installed directly on the polarizer P or the substrate 2. 1 to 4 illustrate a case where the transparent block layer 1 is only on one side of the polarizer P, but the transparent block layer 1 can be installed on both sides of the polarizer P.

In addition, the laminated optical body of FIGS. 1 and 3 is a case where the transparent block layer 1 is between the polarizer P and the adhesive layer 3. In the optical laminate of FIGS. 1 and 3, the transparent block layer 1 can be installed directly on the polarizer P. When producing the optical laminate of FIGS. 1 and 3, a polarizing film having a polarizer P and a transparent block layer 1 formed directly on the polarizer P can be prepared. In addition, when producing the optical laminate of FIG. 3, a single-protection polarizing film can be prepared in which the protective film 4 is provided on one side of the polarizer P opposite to the side having the transparent block layer. The laminated optical body of FIGS. 2 and 4 is a case where the transparent block layer 1 is between the adhesive layer 3 and the substrate 2. In the optical laminate of FIGS. 2 and 4, the transparent block layer 1 can be installed directly on the substrate 2.

As shown in FIGS. 3 and 4, the optical laminate of the present invention can be provided with a protective film 4 on the polarizer P. The optical laminated body of FIGS. 3 and 4 is a case where the protective film 4 is provided on the optical laminated body of FIGS. 1 and 2. In addition, although not shown, the polarizer P and the protective film 4 are laminated through intervening layers such as an adhesive layer, an adhesive layer, and an undercoat layer (primer layer). Although not shown, the easily adhesive layer and the adhesive layer can be laminated by providing an easily adhesive layer on the protective film 4 or performing an activation treatment.

Although not shown, an optical layer or optical member other than the transparent block layer 1 is formed between the polarizer P and the substrate 2 in the optical laminate of FIGS. 1 to 4 using a pressure-sensitive adhesive layer or adhesive. It can be laminated with layers interposed. Even when the optical layer or optical member is one in which eluted components are generated under humidifying heat conditions, the present invention is effective in preventing transfer of the eluted components to the polarizer and suppressing deterioration of optical properties. Additionally, a surface protection film can be appropriately provided on the optical laminated body of the present invention.

<Polarizer>

The polarizer is not particularly limited, and various types of polarizers can be used. As a polarizer, for example, a dichroic substance such as iodine or a dichroic dye is adsorbed on a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film, and is stretched uniaxially. Examples include polyene-based oriented films, such as dehydrated polyvinyl alcohol and dechlorinated polyvinyl chloride treated products. Among these, a polarizer made of a polyvinyl alcohol-based film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 80 μm or less.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and stretching it uniaxially can be created, for example, by immersing a polyvinyl alcohol-based film in an aqueous iodine solution, dyeing it, and stretching it to 3 to 7 times the original length. If necessary, it may be immersed in an aqueous solution such as potassium iodide, which may contain boric acid, zinc sulfate, zinc chloride, etc. Additionally, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol-based film with water to remove contamination and anti-blocking agents from the surface of the polyvinyl alcohol-based film, swelling the polyvinyl alcohol-based film also has the effect of preventing uneven dyeing and other unevenness. Stretching may be performed after dyeing with iodine, may be carried out while dyeing, or may be carried out after stretching and then dyed with iodine. It can be stretched in an aqueous solution such as boric acid or potassium iodide or in a water bath.

In the present invention, a polarizer with a thickness of 10 μm or less can be used. The thickness of the polarizer is preferably 8 μm or less from the viewpoint of thinning, and is preferably 7 μm or less, and further preferably 6 μm or less. Meanwhile, the thickness of the polarizer is preferably 2 μm or more, and further preferably 3 μm or more. Such a thin polarizer has little thickness unevenness, has excellent visibility, and has excellent durability against thermal shock because there is little dimensional change.

As a thin polarizer, typically

Japanese Patent No. 4751486 specification,

Japanese Patent No. 4751481 specification,

Japanese Patent No. 4815544 specification,

Japanese Patent No. 5048120 specification,

International Publication No. 2014/077599 Pamphlet,

Pamphlet International Publication No. 2014/077636,

and thin polarizers described in the above or thin polarizers obtained from the manufacturing methods described in these.

The polarizer has optical properties expressed by the single transmittance T and polarization degree P by the following formula:

P>-(10 ^0.929T-42.4 -1)×100 (however, T<42.3), or

It is configured to satisfy the condition of P≥99.9 (however, T≥42.3). A polarizer configured to satisfy the above conditions has the performance required as a display for a liquid crystal TV using a uniquely large display element. Specifically, the contrast ratio is 1000:1 or more, and the maximum luminance is 500 cd/m ² or more. As another use, for example, it is bonded to the viewing side of an organic EL display device.

As the above-mentioned thin polarizer, it can be stretched at a high magnification and its polarization performance can be improved even among the manufacturing methods including the step of stretching in the state of a laminate and the step of dyeing. Accordingly, in Japanese Patent No. 4751486 and Japanese Patent No. 4751481. It is preferably obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in the specification of Japanese Patent No. 4815544, and in particular, the aqueous boric acid solution described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544. It is preferable to obtain it by a manufacturing method that includes a step of auxiliary stretching in the air before stretching in the air. These thin polarizers can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a resin substrate for stretching in the state of a laminate, and a dyeing step. With this manufacturing method, even if the PVA-based resin layer is thin, it is possible to stretch without problems such as breakage during stretching because it is supported by the resin base material for stretching.

<Substrate>

The optical laminate of the present invention uses a substrate containing an ionic component. The substrate elutes ionic components to the adhesive layer side. The optical laminate of the present invention is effective when using such a substrate. The eluted components of the substrate can be specifically confirmed by the following method or the method described in the Examples.

This can be done by, for example, boiling a substrate in hot water at 120°C for 1 hour and detecting ion components from the water used to boil the substrate, where such eluted components can occur. If the amount of sodium ions detected is 0.1 ㎍/g or more, it can be confirmed that the substrate is capable of generating eluted components.

Examples of the substrate include a glass substrate. In particular, the alkaline glass substrate contains a sodium component, and it is detected that sodium ions are eluted. Such alkaline glass substrates also include chemically strengthened glass such as Gorilla Glass manufactured by Corning, which is used as a cover glass in display devices. The thickness of the substrate is usually about 1 to 5000 μm, and preferably 300 to 2000 μm.

<Transparent block layer>

The transparent block layer is a layer that can prevent migration of eluted components from the substrate.

The thickness of the transparent block layer is preferably 3 μm or less from the viewpoint of thinning and optical reliability, more preferably 2 μm or less, more preferably 1.5 μm or less, and more preferably 1 μm or less. On the other hand, the thickness of the transparent block layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, and more preferably 0.3 μm or more from the viewpoint of demonstrating sufficient block properties.

A material forming the transparent block layer can be used that has transparency and can prevent migration of eluted components. Examples of such materials include forming materials containing urethane prepolymer, which is a reaction product of an isocyanate compound and a polyhydric alcohol.

As the isocyanate compound, for example, a polyfunctional isocyanate compound is preferable, and specific examples include polyfunctional aromatic isocyanate compounds, alicyclic isocyanates, aliphatic isocyanate compounds, or dimers thereof.

Examples of polyfunctional aromatic isocyanate compounds include phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, and 4,4'-diphenylmethane diisocyanate. Isocyanate, 4,4'-tuluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, methylenebis4- Phenyl isocyanate, p-phenylene diisocyanate, etc. are mentioned.

Examples of polyfunctional alicyclic isocyanate compounds include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-bisisocyanatomethylcyclohexane, and isophorone. Diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated tetramethylxylylene diisocyanate, etc. are mentioned.

Examples of polyfunctional aliphatic isocyanate compounds include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, and dodecamethylene diisocyanate. Isocyanate, 2,4,4-trimethylhexamethylene diisocyanate, etc. are mentioned.

Moreover, polyfunctional isocyanate compounds include those having three or more isocyanate groups such as isocyanuric acid tris(6-isocyanatehexyl).

Polyhydric alcohols include, for example, ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3- Propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1 , 8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, polypropylene glycol, etc.

As the urethane prepolymer, in the present invention, it is preferable to use a rigid structure in which the cyclic structure (benzene ring, cyanurate ring, isocyanurate ring, etc.) occupies a large proportion of the molecular structure. For example, the polyfunctional isocyanate compound can be used individually or in combination of two or more types, but from the viewpoint of adjusting the moisture content, an aromatic isocyanate compound is preferable. Other polyfunctional isocyanate compounds can be used in combination with aromatic isocyanate compounds. In particular, among aromatic isocyanate compounds, it is preferable to use at least one type selected from tolylene diisocyanate and diphenylmethane diisocyanate as the isocyanate compound.

As the urethane prepolymer, trimethylolpropane-tri-tolylene isocyanate and trimethylolpropane-tri-diphenylmethane diisocyanate are preferably used.

Additionally, the urethane prepolymer may be one in which a protective group is added to the terminal isocyanate group. Protecting groups include oximes and lactams. The protected isocyanate group is heated to dissociate the protecting group from the isocyanate group, causing the isocyanate group to react.

Additionally, a reaction catalyst can be used to increase the reactivity of the isocyanate group. The reaction catalyst is not particularly limited, but a tin-based catalyst or an amine-based catalyst is preferred. One type or two or more types of reaction catalysts may be used. The amount of reaction catalyst used is usually 5 parts by weight or less per 100 parts by weight of urethane prepolymer. If the amount of reaction catalyst is large, the crosslinking reaction speed increases and foaming of the forming material occurs. Even if a foamed forming material is used, sufficient adhesiveness cannot be obtained. Typically, when using a reaction catalyst, 0.01 to 5 parts by weight, and even 0.05 to 4 parts by weight, is preferable.

As the tin-based catalyst, either inorganic or organic catalysts can be used, but organic catalysts are preferred. Examples of the inorganic tin-based catalyst include stannous chloride, stannous chloride, and the like. The organic tin-based catalyst preferably has at least one organic group such as an aliphatic group or alicyclic group having a skeleton such as a methyl group, ethyl group, ether group, or ester group. Examples include tetra-n-butyltin, tri-n-butyltin acetate, n-butyltin trichloride, trimethyltin hydroxide, dimethyltin dichloride, and dibutyltin dilaurate.

Additionally, the amine-based catalyst is not particularly limited. For example, it is preferable to have at least one organic group such as an alicyclic group such as quinuclidine, amidine, or diazabicycloundecene. In addition, triethylamine and the like can be cited as amine-based catalysts. Additionally, examples of reaction catalysts other than the above include cobalt naphthenate, benzyltrimethylammonium hydroxide, and the like.

The urethane prepolymer is typically used as a solution. The solution may be solvent-based or aqueous-based such as an emulsion, colloidal dispersion, or aqueous solution. The organic solvent is not particularly limited as long as it uniformly dissolves the components constituting the forming material. Examples of organic solvents include toluene, methyl ethyl ketone, and ethyl acetate. Also, even in the case of an aqueous solution, for example, alcohols such as n-butyl alcohol and isopropyl alcohol, and ketones such as acetone can be blended. In the case of an aqueous system, it can be performed by using a dispersant or by introducing a water-dispersible component such as polyethylene glycol or a functional group with low reactivity with isocyanate groups such as carboxylate, sulfonate, or quaternary ammonium salt into the urethane prepolymer.

Materials for forming a transparent block layer other than the urethane prepolymer include, for example, cyanoacrylate-based forming materials and epoxy-based forming materials.

The formation of the transparent block layer can be appropriately selected depending on the type of the forming material. For example, it can be performed by applying the forming material to a polarizer or a resin film and then curing it, and the transparent block layer can be obtained as an application layer. Typically, this is performed by forming a cured layer by drying at about 30 to 100°C, preferably 50 to 80°C, for about 0.5 to 15 minutes after the application. In addition, when the forming material contains an isocyanate component, annealing treatment can be performed at about 30 to 100°C, preferably at 50 to 80°C for about 0.5 to 24 hours to promote the reaction.

<Adhesive layer>

In the optical laminate of the present invention, the adhesive layer used for bonding the polarizer may be one used in a polarizing film. Additionally, the adhesive layer can be laminated through an intervening layer such as an undercoat layer (primer layer).

An appropriate adhesive can be used to form the adhesive layer, and there are no particular restrictions on its type. Examples of adhesives include rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives.

Among these adhesives, those that have excellent optical transparency, exhibit appropriate adhesive properties of wettability, cohesiveness, and adhesiveness, and have excellent weather resistance, heat resistance, etc., are preferably used. An acrylic adhesive is preferably used as it exhibits these characteristics.

A method of forming an adhesive layer includes, for example, applying the adhesive to a peeled separator, drying and removing the polymerization solvent to form an adhesive layer, and then transferring the adhesive to a transparent block layer. It is manufactured by applying, drying and removing the polymerization solvent, etc. to form an adhesive layer on the polarizer. In addition, when applying the adhesive, one or more solvents other than the polymerization solvent may be newly added as appropriate.

As the separator subjected to the release treatment, a silicone release liner is preferably used. In the process of forming a pressure-sensitive adhesive layer by applying and drying the pressure-sensitive adhesive of the present invention on such a liner, an appropriate and appropriate method may be adopted depending on the purpose as a method of drying the pressure-sensitive adhesive. Preferably, a method of heating and drying the coating film is used. The heat drying temperature is preferably 40°C to 200°C, more preferably 50°C to 180°C, and particularly preferably 70°C to 170°C. By keeping the heating temperature within the above range, an adhesive with excellent adhesive properties can be obtained.

As for the drying time, any suitable time can be adopted. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

Various methods are used as a method of forming the adhesive layer. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, deep roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, extrusion by die coater, etc. Methods such as the coat method can be mentioned.

The thickness of the adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm. Preferably it is 2 to 50 ㎛, more preferably 2 to 40 ㎛, and even more preferably 5 to 35 ㎛.

When the adhesive layer is exposed, the adhesive layer may be protected with a peeled sheet (separator) until it is actually used.

As the constituent materials of the separator, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film, porous materials such as paper, cloth, and non-woven fabric, and appropriate thin materials such as nets, foam sheets, metal foil, and laminates thereof. However, plastic films are preferably used because they have excellent surface smoothness.

The plastic film is not particularly limited as long as it is a film that can protect the adhesive layer, and examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, and vinyl chloride copolymer. Film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc. can be mentioned.

The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. If necessary, the separator can be subjected to mold release and antifouling treatment using silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agents, silica powder, etc., and antistatic treatment such as coating type, kneading-type, or vapor deposition type. . In particular, by appropriately performing a peeling treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the separator, the peelability from the adhesive layer can be further improved.

<Protective film>

The material constituting the protective film is preferably one having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc. For example, polyester polymers such as polyethylene terephthalate or polyethylene naphthalate, cellulose polymers such as diacetylcellulose or triacetylcellulose, acrylic polymers such as polymethyl methacrylate, polystyrene or acrylonitrile-styrene copolymer (AS) Resins), styrene-based polymers, polycarbonate-based polymers, etc. can be mentioned. In addition, polyethylene, polypropylene, polyolefins with cyclo or norbornene structures, polyolefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamide, imide-based polymers, and sulfone-based polymers. Polymer, polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy. Systemic polymers or blends of the above polymers can also be cited as examples of polymers forming the protective film.

The protective film is applied to the side opposite to the side to which the substrate is applied based on the polarizer. Since it is optional to provide the transparent block layer of the present invention on the opposite side of the polarizer, it is preferable to use a material that does not generate eluted components even under a high temperature and high humidity environment as the protective film. Materials for such protective films include acrylic polymers and polyolefin polymers.

Additionally, the protective film may contain one or more suitable additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, discoloration inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, colorants, etc. The content of the thermoplastic resin in the protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, further preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. If the content of the thermoplastic resin in the protective film is 50% by weight or less, there is a risk that the inherent high transparency of the thermoplastic resin may not be sufficiently expressed.

As the protective film, retardation film, brightness enhancement film, diffusion film, etc. can also be used. Examples of the retardation film include those having a front retardation of 40 nm or more and/or a thickness direction retardation of 80 nm or more. The front phase difference is typically controlled in the range of 40 to 200 nm, and the thickness direction retardation is typically controlled in the range of 80 to 300 nm. When using a retardation film as a protective film, thickness reduction can be achieved because the retardation film also functions as a polarizer protective film.

Examples of the retardation film include birefringent films obtained by uniaxially or biaxially stretching a thermoplastic substrate. The stretching temperature, stretching ratio, etc. are appropriately set depending on the retardation value, film material, and thickness.

The thickness of the protective film can be determined appropriately, but is generally about 1 to 500 μm in terms of strength, workability such as handling, and thinness. In particular, 1 to 300 μm is preferable, 5 to 200 μm is more preferable, and furthermore, in the case of a thin thickness of 5 to 150 μm, especially 20 to 100 μm, it is particularly preferable.

A functional layer such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer, or an anti-glare layer may be installed on the side of the protective film that does not adhere the polarizer. In addition, the functional layers such as the hard coat layer, anti-reflection layer, anti-sticking layer, diffusion layer, and anti-glare layer can be installed on the protective film itself, or can be installed separately from the protective film.

<Intervening layer>

The protective film and the polarizer are laminated through intervening layers such as an adhesive layer, an adhesive layer, and an undercoat layer (primer layer). At this time, it is preferable to stack the two without an air gap using an intervening layer.

The adhesive layer is formed by an adhesive. The type of adhesive is not particularly limited, and a variety of adhesives can be used. The adhesive layer is not particularly limited as long as it is optically transparent, and various types of adhesives such as water-based, solvent-based, hot melt-based, and active energy ray-curable adhesives are used, but water-based adhesives or active energy ray-curable adhesives are preferred.

Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex-based adhesives, and water-based polyester. Water-based adhesives are generally used as adhesives made of an aqueous solution, and usually contain a solid content of 0.5 to 60% by weight.

Active energy ray-curable adhesives are adhesives that cure by active energy rays such as electron beams or ultraviolet rays (radical curing type, cation curing type), and can be used in, for example, electron beam curing type or ultraviolet curing type. The active energy ray-curable adhesive may be, for example, a photo-radical curable adhesive. When an active energy ray curable adhesive of the photo radical curable type is used as an ultraviolet curable adhesive, the adhesive contains a radical polymerizable compound and a photopolymerization initiator.

The adhesive coating method is appropriately selected depending on the adhesive's viscosity or desired thickness. Examples of coating methods include, for example, reverse coater, gravure coater (direct, reverse, or offset), bar reverse coater, roll coater, die coater, bar coater, and rod coater. In addition, methods such as a dipping method can be appropriately used for coating.

In addition, when applying the adhesive using a water-based adhesive or the like, it is preferable that the thickness of the adhesive layer finally formed is 30 to 300 nm. The thickness of the adhesive layer is more preferably 60 to 250 nm. On the other hand, when using an active energy ray-curable adhesive, the thickness of the adhesive layer is preferably 0.1 to 200 μm. More preferably, it is 0.5 to 50 μm, and even more preferably, it is 0.5 to 10 μm.

Additionally, in lamination of a polarizer and a protective film, an easily adhesive layer can be provided between the protective film and the adhesive layer. The easily adhesive layer can be formed of various resins having, for example, a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based skeleton, a polyamide skeleton, a polyimide skeleton, and a polyvinyl alcohol skeleton. These polymer resins can be used individually or in combination of two or more types. Additionally, other additives may be added to form the easily adhesive layer. Specifically, stabilizers such as tackifiers, ultraviolet absorbers, antioxidants, and heat-resistant stabilizers may be used.

The easily adhesive layer is usually provided in advance on a protective film, and the easily adhesive layer side of the protective film and the polarizer are laminated with an adhesive layer. The formation of the easily adhesive layer is accomplished by coating and drying the forming material of the easily adhesive layer on a protective film using a known technique. The forming material for the easily adhesive layer is usually adjusted as a solution diluted to an appropriate concentration in consideration of the thickness after drying, the smoothness of coating, etc. The thickness of the easily adhesive layer after drying is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm, and even more preferably 0.05 to 1 μm. In addition, the easily adhesive layer can be installed in multiple layers, but even in this case, it is preferable that the total thickness of the easily adhesive layer is within the above range.

The adhesive layer is formed from an adhesive. Various adhesives can be used as the adhesive, for example, rubber adhesive, acrylic adhesive, silicone adhesive, urethane adhesive, vinyl alkyl ether adhesive, polyvinylpyrrolidone adhesive, polyacrylamide adhesive, cellulose adhesive, etc. there is. An adhesive base polymer is selected depending on the type of adhesive. Among the above adhesives, an acrylic adhesive is preferably used because it has excellent optical transparency, exhibits appropriate wettability, cohesiveness and adhesive properties, and has excellent weather resistance and heat resistance.

The undercoat layer (primer layer) is formed to improve adhesion between the polarizer and the protective film. The material constituting the primer layer is not particularly limited as long as it exhibits a certain degree of strong adhesion to both the base film and the polyvinyl alcohol-based resin layer. For example, thermoplastic resins with excellent transparency, thermal stability, stretchability, etc. are used. Examples of thermoplastic resins include acrylic resins, polyolefin-based resins, polyester-based resins, polyvinyl alcohol-based resins, and mixtures thereof.

<Surface protection film>

A surface protection film can be provided on the optical laminate of the present invention. The surface protection film usually has a base film and an adhesive layer, and protects the polarizer through the adhesive layer.

As the base film for the surface protection film, a film material having isotropy or close to isotropy is selected from the viewpoint of inspectionability, management, etc. As the film material, for example, polyester resin such as polyethylene terephthalate film, cellulose resin, acetate resin, polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, Examples include transparent polymers such as acrylic resin. Among these, polyester resin is preferable. The base film can be used as a laminate of one or two or more types of film materials, or a stretched product of the above film can also be used. The thickness of the base film is generally 500 μm or less, preferably 10 to 200 μm.

As an adhesive to form the adhesive layer of the surface protection film, an adhesive whose base polymer is a (meth)acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based polymer, or rubber-based polymer can be appropriately selected and used. there is. From the viewpoints of transparency, weather resistance, heat resistance, etc., an acrylic adhesive using an acrylic polymer as a base polymer is preferable. The thickness of the adhesive layer (dry film thickness) is determined depending on the required adhesive strength. It is usually about 1 to 100㎛, preferably 5 to 50㎛.

Additionally, in the surface protection film, a release treatment layer can be provided using a low-adhesive material such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface opposite to the surface of the base film on which the adhesive layer is provided.

<Other optical layers>

In actual use, the optical laminate of the present invention can be used by laminating optical layers other than the polarizer. There is no particular limitation on the optical layer, but for example, it is used in the formation of liquid crystal display devices such as reflectors, transflectors, retardation plates (including 1/2 or 1/4 wave plates), and visual compensation films. You can use the 1st or 2nd floor or more of the optical floor where the enemy is. In particular, a reflective polarizing film or a semi-transmissive polarizing film formed by laminating a protective film (resin film), a reflector or a transflective reflector in addition to the polarizer of the present invention, and an elliptically polarizing film or circle formed by laminating a retardation plate in addition to the polarizing film. A polarizing film, a wide viewing angle polarizing film formed by laminating a visual compensation film in addition to a polarizing film, or a polarizing film formed by laminating a brightness enhancement film in addition to a polarizing film is preferable.

An optical laminate in which the above optical layer is laminated on a polarizer can be formed by sequentially laminating them separately during the manufacturing process of a liquid crystal display device, etc., but pre-lamination to form an optical film is superior in quality stability and assembly work. There is an advantage in improving the manufacturing process of liquid crystal display devices, etc. For lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the above-mentioned polarizing film or other optical films, their optical axes can be set at an appropriate arrangement angle depending on the desired retardation characteristics, etc.

The optical laminate of the present invention can be suitably used for forming various image display devices such as liquid crystal display devices and organic EL display devices. Formation of the liquid crystal display device can be performed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing film or optical film, and a lighting system as needed and incorporating a driving circuit, but in the present invention, the optical laminate according to the present invention is used. There is no particular limitation except for this point, and the conventional method can be used. As for the liquid crystal cell, for example, any type such as IPS type or VA type can be used, but IPS type is particularly preferable.

An appropriate liquid crystal display device can be formed, such as a liquid crystal display device in which an optical laminated body is disposed on one or both sides of a liquid crystal cell, or a lighting system using a backlight or a reflector. In that case, the optical laminate according to the present invention can be installed on one side or both sides of the liquid crystal cell. When installing polarizing films or optical films on both sides, they may be the same or different. In addition, when forming a liquid crystal display device, appropriate components such as a diffusion plate, an anti-glare layer, an anti-reflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight are placed in appropriate positions in one or two or more layers. can do.

Additionally, the optical laminated body of the present invention can be applied to the cover glass of an image display device.

In addition, the optical laminate of the present invention can be applied to a liquid crystal substrate or resin film of an image display device, etc.

[Example]

Below, the present invention will be described by way of examples, but the present invention is not limited to the examples shown below. In addition, all parts and percentages in each example are based on weight. All room temperature leaving conditions unless specifically specified below are 23°C 65% R.H. am.

(Production of thin polarizer)

Corona treatment was performed on one side of an amorphous isophthalic acid copolymerization polyethylene terephthalate (IPA copolymerization PET) film (thickness: 100 μm) substrate with an absorption rate of 0.75% and a Tg of 75°C, and polyvinyl alcohol (degree of polymerization 4200) was applied to this corona-treated side. , saponification degree of 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree of 1200, acetoacetyl modification degree of 4.6%, saponification degree of 99.0 mol% or more, manufactured by Japan Synthetic Chemical Industry Co., Ltd., brand name 'Gosephimer Z200') in a ratio of 9:1. The containing aqueous solution was applied and dried at 25°C to form a PVA-based resin layer with a thickness of 11 μm, and a laminate was produced.

The obtained laminate was free-end uniaxially stretched 2.0 times in the machine direction (longitudinal direction) between rolls with different circumferential speeds in an oven at 120°C (air auxiliary stretching treatment).

Next, the laminate was immersed in an insolubilization bath (an aqueous boric acid solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30°C for 30 seconds (insolubilization treatment).

Next, the polarizing plate was immersed in a dyeing bath with a liquid temperature of 30°C while adjusting the iodine concentration and immersion time so as to achieve a predetermined transmittance. In this example, 0.2 parts by weight of iodine and 1.0 parts by weight of potassium iodide were added to 100 parts by weight of water, and the resulting mixture was immersed in an iodine aqueous solution for 60 seconds (dyeing treatment).

Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 3 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 (crosslinking treatment).

Thereafter, the laminate was immersed in an aqueous solution of boric acid (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, and the laminate was mixed between rolls with different circumferential speeds. Uniaxial stretching was performed so that the total stretching ratio was 5.5 times in the longitudinal direction (underwater stretching treatment).

Thereafter, the laminate was immersed in a washing bath (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).

As a result of the above, an optical film laminate containing a polarizer with a thickness of 5 μm was obtained.

(protective film)

Acrylic: Corona treatment was performed on the easily adhesive treated surface of a (meth)acrylic substrate having a lactone ring structure with a thickness of 40 μm and used.

TAC: A triacetylcellulose-based resin film manufactured by Fujifilm, product name 'TJ40', 40㎛ thick was used.

COP: A 25㎛ thick cycloolefin resin film manufactured by Zeon Japan, product name 'Zeonoa Film', was used.

(Production of adhesive)

10 parts by weight of N-hydroxyethyl acrylamide, 30 parts by weight of acryloylmorpholine, 45 parts by weight of 1,9-nonanediol diacrylate, 10 parts of an acrylic oligomer (ARUFONUP1190, manufactured by Dong-A Synthetic Co., Ltd.) made by polymerizing (meth)acrylic monomer 1 part, 3 parts photopolymerization initiator (IRGACURE 907, manufactured by BASF) and 2 parts polymerization initiator (KAYACURE DETX-S, manufactured by Nippon Chemical Company) were mixed to prepare an ultraviolet curing adhesive.

(Production of single-protection polarizing film)

The protective film (acrylic) is bonded to the surface of the polarizer of the optical film laminate while applying the UV-curable adhesive so that the thickness of the adhesive layer after curing is 1 μm, and then ultraviolet rays are irradiated as active energy rays to form the adhesive. was hardened. Ultraviolet irradiation was performed using a gallium-filled metal halide lamp, irradiation device: Light HAMMER10 manufactured by Fusion UV Systems, Inc., valve: V valve, peak irradiance: 1600 mW/cm ² , integrated irradiation amount 1000/mJ/cm ² (wavelength 380 to 440 nm). was used, and the illuminance of ultraviolet rays was measured using the Sola-Check system manufactured by Solatell. Next, the amorphous PET substrate was peeled off, and a single-protection polarizing film using a thin polarizer was produced. The optical properties of the obtained polarizing film were a single transmittance of 42.8% and a polarization degree of 99.99%.

<Formation material of transparent block layer>

Forming material A: 100 parts of a 75% ethyl acetate solution of urethane prepolymer consisting of tolylene diisocyanate and trimethylolpropane (manufactured by Tosoh Corporation, brand name 'Colonate L') and a dioctyltin dilaurate-based catalyst (manufactured by Tokyo Fine Chemical Company). , brand name 'Envirizer OL-1') was added to prepare a urethane prepolymer coating solution with a solid content concentration of 10% using methyl isobutyl ketone as a solvent.

Forming material B: Using the same catalyst and solvent as forming material A, except that a 75% ethyl acetate solution of urethane prepolymer consisting of diphenylmethane diisocyanate and trimethylolpropane (manufactured by Tosoh Corporation, product name 'Colonate 2067') was used. A coating solution was prepared.

Forming material C: Coating using the same catalyst and solvent as forming material A, except that a 75% ethyl acetate solution of urethane prepolymer consisting of hexamethylene diisocyanate and trimethylolpropane (manufactured by Tosoh Corporation, product name 'Colonate HL') was used. The solution was prepared.

Forming material D: 80 parts of urethane acrylate resin (manufactured by Nippon Synthetic Co., Ltd., product name 'Jakwang UV-1700'), 80 parts of hydroxyethyl acrylamide (manufactured by Kojin Co., product name 'HEAA') and a photopolymerization initiator (manufactured by Chiba Japan Co., product name) 'Irgacure 907') was added, and a urethane acrylate coating solution was prepared at a solid content concentration of 10% using methyl isobutyl ketone as a solvent.

Forming material E: Polyvinyl alcohol resin (manufactured by Nippon Sakubi Pobal, brand name: JC-25) with a degree of polymerization of 2500 and a degree of saponification of 99.0% was dissolved in pure water, and an aqueous solution with a solid content concentration of 4% by weight was prepared.

<Glass substrate>

Alkali glass: Micro slide glass manufactured by Matsunami Glass Co., Ltd. with a thickness of 1200 to 1500 μm was used.

Gorilla Glass: 700㎛ thick product name 'Gorilla Glass 2' manufactured by Corning Company was used.

Alkali-free glass: 700㎛ thick product name 'Eagle XG' manufactured by Corning Company was used.

<Detection of Na ions on glass substrate>

Each glass substrate (50 mm x 50 mm) was heated and extracted in 50 ml of hot water at 120°C for 1 hour. Next, the hot water used for boiling was taken out and cooled to room temperature (23°C), and component analysis (Na ions) by ion chromatography was performed on the filtered solution under the following conditions. The results are shown in Table 1.

Analytical device: Thermo Fisher Scientific, ICS-3000 (negative ion)/DX-320 (positive ion)

<Measurement conditions>

Separation column: Dionex Ion Pac CS16

Guard Column: Dionex IonPac CG16

Removal System: Dionex CERS-500

Detector: Electrical conductivity detector

Eluent: MSA aqueous solution

Eluent flow rate: 1.0mL/min

Data injection volume: 25μL

When the amount of sodium ions detected from the extract was 0.1 μg/g or more, it was judged that the substrate was eluted with ionic components to the adhesive layer side.

<Formation of adhesive layer>

In a reaction vessel equipped with a cooling tube, nitrogen introduction tube, thermometer, and stirring device, 100 parts of butyl acrylate, 3 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate, and 0.3 part of 2,2'-azobisisobutyronitrile were added to ethyl acetate. A solution was prepared by adding together. Next, this solution was stirred while blowing nitrogen gas, and reacted at 55°C for 8 hours to obtain a solution containing an acrylic polymer with a weight average molecular weight of 2.2 million. Additionally, ethyl acetate was added to the solution containing the acrylic polymer to obtain an acrylic polymer solution whose solid content was adjusted to 30%.

Based on 100 parts of the solid content of the acrylic polymer solution, 0.5 part of a cross-linking agent mainly composed of a compound having an isocyanate group (manufactured by Nippon Polyurethane Co., Ltd., product name 'Colonate L') and 0.075 parts of γ-gly as a silane coupling agent. Sidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., brand name 'KMB-403') was mixed in this order to prepare an adhesive solution. The adhesive solution was applied to the surface of a release sheet (separator) made of a peeled polyethylene terephthalate film (thickness 38 μm) so that the thickness after drying was 20 μm, and dried to form an adhesive layer.

Example 1

<Production of a polarizing film with transparent block layer attachment>

This is carried out by applying the transparent block layer forming material A to the polarizer side of the polarizing film (the polarizer side on which the protective film is not installed) using a bar coater, and then heat treating it at 60°C for 12 hours. , a 1㎛ thick urethane resin layer was formed.

<Production of optical laminate>

Next, the adhesive layer formed on the peeled surface of the release sheet (separator) was bonded to the transparent block layer formed on the piece protection polarizing film, and a polarizing film with an adhesive layer was produced. Next, after peeling the release sheet from the adhesive layer of the polarizing film with an adhesive layer, the said glass substrate (alkali glass) was bonded to the said adhesive layer.

Example 2

A glass substrate with a transparent block layer and an optical laminate were produced in the same manner as in Example 1, except that the type of the glass substrate was changed as shown in Table 1.

Example 3

A glass substrate with a transparent block layer and an optical laminate were produced in the same manner as in Example 1, except that the thickness of the transparent block layer was changed as shown in Table 1.

Example 4

<Production of glass substrate with transparent block layer>

After applying the transparent block layer forming material A to the glass substrate (alkali glass) using a bar coater, heat treatment was performed at 60° C. for 12 hours to form a urethane resin layer with a thickness of 1 μm.

<Production of optical laminate>

Next, the adhesive layer formed on the peeled surface of the release sheet (separator) is bonded to the polarizer side of the above-mentioned protective polarizing film (the polarizer side without the protective film) to produce a polarizing film with an adhesive layer. did. Next, after peeling the release sheet from the adhesive layer of the polarizing film with an adhesive layer, the transparent block layer (urethane resin layer) side of the said transparent block layer-equipped board|substrate was bonded to the said adhesive layer.

Example 5

In Example 4, a glass substrate with a transparent block layer and an optical laminate were produced in the same manner as in Example 4, except that the forming material of the transparent block layer was changed as shown in Table 1.

Example 6

<Production of a polarizing film with transparent block layer attachment>

After applying the transparent block layer forming material A to the polarizer side of the polarizing film (polarizer side on which the protective film is not installed) using a bar coater, heat treatment is performed at 60° C. for 12 hours. , a 1㎛ thick urethane resin layer was formed.

<Production of optical laminate>

Next, the adhesive layer formed on the release-treated surface of the release sheet (separator) was bonded to the transparent block layer formed on the piece protection polarizing film, and then the release sheet was peeled. Next, a triacetylcellulose (TAC) film with a thickness of 40 μm is bonded to the pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive layer formed on the peeled surface of the release sheet (separator) is bonded to form a polarized light with the pressure-sensitive adhesive layer attached to the TAC film. A film was produced. Next, after peeling the release sheet from the adhesive layer of the polarizing film with an adhesive layer, the said glass substrate (alkali glass) was bonded to the said adhesive layer.

Examples 7 to 8, Comparative Examples 1 to 6, Reference Example 1

In Example 1, except that the type of protective film, the forming material of the transparent block layer, the thickness, and the type of the glass substrate were changed as shown in Table 1, the same procedure was performed as in Example 1, and a polarized light with transparent block layer was provided. Films and optical laminates were fabricated.

In addition, the formation of the transparent block layer in Comparative Example 4 was performed by applying the forming material D to the polarizer side of the polarizing film (the polarizer side on which the protective film is not installed) using a bar coater, and then applying 1 ℃ at 60°C. It was heated for a minute. After heating, the coating layer was irradiated with ultraviolet rays with a cumulative amount of 300 mJ/cm ² using a high-pressure mercury lamp to form a urethane acrylate resin layer with a thickness of 1 μm.

Formation of the transparent block layer of Comparative Example 5 was performed by applying the forming material E to the polarizer side of the protective polarizing film (the polarizer side on which the protective film is not installed) using a bar coater, and then heating at 60°C for 3 minutes. This was performed by forming a polyvinyl alcohol resin layer with a thickness of 1㎛.

In Comparative Example 1 and Example 1, a transparent block layer was not formed.

The following evaluation was performed on the optical laminate with a substrate obtained in the above examples and comparative examples. The results are shown in Table 1.

<Single transmittance T and polarization degree P of polarizer>

The single transmittance T and polarization degree P of the obtained piece-protected polarizing film were measured using a spectral transmittance meter equipped with an integrating sphere (Dot-3c, Murakami Color Research Institute).

In addition, the degree of polarization P is the transmittance when two identical polarizing films are overlapped so that their transmission axes are parallel (parallel transmittance: Tp) and the transmittance when they are overlapped so that their transmission axes are orthogonal (orthogonal transmittance: Tc) It is obtained by applying to the equation below.

Polarization degree P(%)={(Tp-Tc)/(Tp+Tc)} ^1/2 ×100

Each transmittance is expressed as a Y value with visibility corrected by a 2-degree field of view (C light source) of JIS Z8701, with fully polarized light obtained through a Glenn Teller prism polarizer as 100%.

<Durability: Change rate of polarization degree (optical reliability test)>

The optical laminate obtained in the examples and comparative examples was cut into a size of 25 mm x 50 mm (absorption axis direction was 50 mm) and used as a sample. A test was performed in which the sample was kept in a constant temperature and humidity chamber at 85°C and 85% RH for 500 hours, after which it was taken out and left at room temperature (23°C and 65% RH). The polarization degree of the sample before and after injection was measured using a spectral transmittance meter with an integrating sphere (Dot-3c from Murakami Color Technology Research Institute),

The rate of change in polarization degree (%) = (1-(polarization degree after input/polarization degree before input)) was calculated.

From the above change rate, the results of evaluating the block effect based on the following criteria are also shown in Table 1.

○: Change rate is 2% or less

×: Rate of change exceeds 2%

[Table 1]

P: polarizer
1: Transparent block layer
2: Substrate
3: Adhesive layer
4: Protective film

Claims (11)

An optical laminate in which a polarizer is bonded to a substrate containing an ionic component through an adhesive layer,
The substrate is to elute ionic components to the adhesive layer side,
Between the polarizer and the substrate, there is a transparent block layer that suppresses migration of the ionic component to the polarizer side,
The transparent block layer is a cured product of a forming material containing a urethane prepolymer, which is a reaction product of an isocyanate compound and a polyhydric alcohol, and has a thickness of 3 μm or less. According to paragraph 1,
An optical laminate, characterized in that the substrate is an alkaline glass substrate. According to paragraph 1,
An optical laminate, wherein when the substrate is boiled in hot water at 120°C for 1 hour, the amount of sodium ions detected from the boiling water is 0.1 μg/g or more. According to paragraph 1,
The optical laminate is characterized in that the transparent block layer is formed directly on the polarizer or the substrate. According to paragraph 1,
An optical laminate, characterized in that the thickness of the polarizer is 10 μm or less. delete delete According to paragraph 1,
An optical laminate, characterized in that the isocyanate compound contains at least one selected from tolylene diisocyanate and diphenylmethane diisocyanate. According to paragraph 1,
An optical laminate characterized by having a protective film on one side of the polarizer opposite to the side having the transparent block layer. A polarizing film used in the optical laminate according to any one of claims 1 to 5, 8, and 9,
A polarizing film characterized by having a polarizer and a transparent block layer formed directly on the polarizer. An image display device having the optical laminated body according to any one of claims 1 to 5, 8, and 9.