KR100724323B1 - Optical film with adhesive and liquid crystal display device - Google Patents

Abstract

In the optical film with an adhesive which has an adhesive layer in at least one surface of the optical film of this invention, Tg of an adhesive layer is -35 degrees C or less. Such an optical film with an adhesive has durability which can suppress the curvature of an optical film, even if it is placed in the low temperature environment of room temperature or less.

Optical film with pressure-sensitive adhesive, image display device

Description

Optical film with an adhesive and image display device {OPTICAL FILM WITH ADHESIVE AND LIQUID CRYSTAL DISPLAY DEVICE}

Field of technology

The present invention relates to an optical film with pressure-sensitive adhesive having a pressure-sensitive adhesive layer on at least one side of the optical film. Furthermore, it is related with image display apparatuses, such as a liquid crystal display device, an organic electroluminescence display, and a PDP using the said optical film with an adhesive. It is preferable that the optical film with an adhesive of this invention contains a stretched film as an optical film, For example, a polarizing plate, a retardation plate, an optical compensation film, a brightness improving film, what these are laminated | stacked, etc. are mentioned.

Background

Liquid crystal displays are used in electronic calculators, watches, televisions, monitors, and the like. Since these products are used under various conditions in various environments, various durability is demanded. In addition, various optical films, such as a polarizing plate and a retardation plate, are used for a liquid crystal display device. These optical films are used by the optical film with an adhesive in order to bond with various optical members. Therefore, durability is calculated | required also about the optical film with an adhesive.

In order to improve the durability of the optical film with an adhesive, various examination is performed about an adhesive layer. For example, there is a method of increasing the molecular weight of the base polymer used for the pressure-sensitive adhesive, copolymerizing a high Tg monomer into the base polymer, or increasing the degree of crosslinking. As said adhesive, acrylic adhesive is used suitably for the outstanding adhesiveness, transparency, etc. (refer patent document 1). However, when the optical film with an adhesive is made durable by these methods, the residual stress of an adhesive layer will become strong. As a result, this acts on the optical film, causing warping in the optical film, causing a big problem of damaging the display quality of the liquid crystal display device.

Patent Document 1: Japanese Patent Application Laid-Open No. 11-52349

Disclosure of the Invention

Problems to be Solved by the Invention

In addition, regarding the durability of the optical film with an adhesive, improving durability under high temperature and high temperature, high humidity conditions was mainly performed. In recent years, as a use of a liquid crystal display device, the use of televisions, a vehicle, etc. is starting to increase. Therefore, durability is demanded for the optical film with an adhesive not only on high temperature and high temperature, high humidity conditions but also on low temperature conditions, such as -30 degreeC. However, even if the optical film with an adhesive (for example, a polarizing plate with an adhesive layer) using a conventional acrylic adhesive can satisfy | fill durability under high temperature and high temperature, high humidity conditions, durability under low temperature conditions of room temperature (23 degreeC) or less is not enough. When the optical film with pressure-sensitive adhesive was exposed to low temperature conditions in a state of being attached to a glass plate or the like, a large warpage occurred.

An object of this invention is to provide the optical film with an adhesive which has the durability which can suppress the curvature of an optical film even when it is left in the low temperature environment below room temperature.

Moreover, an object of this invention is to provide the image display apparatus using the said optical film with an adhesive.

Means to solve the problem

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors discovered that the said objective could be achieved by the following optical film with an adhesive, and came to complete this invention.

That is, this invention is an optical film with an adhesive which has an adhesive layer in at least one surface of an optical film,

Tg (Glass Transition Temperature) of the pressure-sensitive adhesive layer relates to an optical film with pressure-sensitive adhesive, characterized in that less than -35 ℃.

In general, the pressure-sensitive adhesive has a Tg of room temperature or less. The temperature region near Tg is a transition region between the glass state and the rubber state, and when the glass state exceeds Tg, the elastic modulus of the pressure sensitive adhesive rapidly rises, and as a result, the degree of thermal shrinkage of the optical film is sufficiently sufficient for small dimensional change. It cannot be followed, resulting in large warpage.

On the other hand, the warping in the low temperature region, unlike the warping in the heating or humidifying state that is usually tested, in the optical film (especially stretched film) generates a strong warp in the stretching axis and 90 ° direction, the warp is lost when returned to room temperature It is characterized by a return to the original. This is because the stretching axis in the optical film, especially the polarizing plate, and the thermal expansion coefficient in the 90 ° direction are larger than those in the stretching axis direction, and the generated strength is also larger in the stretching axis and in the 90 ° direction. The phenomenon that warpage disappears when returning to room temperature indicates that the warpage in the low temperature region largely depends only on the thermal stress of the optical film.

Therefore, in this invention, when the Tg is -35 degreeC or less as an adhesive layer, the curvature which arises by the stress accompanying the dimensional change of members, such as an optical film, in low temperature area | region is suppressed. Thereby, the optical film with an adhesive with favorable durability can be provided not only in a high temperature region but also in a low temperature region. Tg of an adhesive layer becomes like this. Preferably it is -40 degrees C or less, More preferably, it is -50 degrees C or less. In addition, when Tg is too low, since durability under high temperature conditions falls, it is more preferable that it is -120 degreeC or more and -100 degreeC or more.

The optical film with pressure-sensitive adhesive has a proof strength (F) due to the thermal stress of the optical film,

F = α · ΔT · E · I · h

(Where α is the thermal expansion coefficient at -60 to 23 ° C, ΔT is the temperature difference based on 23 ° C, E is the elastic modulus, I is the width, and h is the thickness)

If made with

It is effective that an optical film has a stretched film and the yield strength F which arises in the 90 degree direction with respect to the stretching axis of the said stretched film at 0 degreeC is 50N or more.

The optical film with the said yield strength F of 50N or more becomes easy to produce curvature at low temperature, and the optical film with an adhesive of this invention can be applied preferably. When the said yield strength F of an optical film has 70N or more, and also 100N or more, the optical film with an adhesive of this invention is preferable.

The optical film with a pressure-sensitive adhesive can be preferably applied to an optical film containing a polarizing plate and / or a retardation plate. As a component of a polarizing plate and / or a retardation plate, what used the stretched film tends to bend at low temperature, and can apply the optical film with an adhesive of this invention suitably.

Moreover, this invention relates to the image display apparatus which used the at least 1 optical film with an adhesive.

To practice the invention  Best form for

The optical film with an adhesive of this invention has an adhesive layer on one side of an optical film. Although the adhesive layer is formed by having a low Tg of -35 degrees C or less, a suitable adhesive can be used for formation of the adhesive layer, There is no restriction | limiting in particular about the kind. Examples of the pressure-sensitive adhesives include rubber pressure sensitive adhesives, acrylic pressure sensitive adhesives, silicone pressure sensitive adhesives, urethane pressure sensitive adhesives, vinyl alkyl ether pressure sensitive adhesives, polyvinyl alcohol pressure sensitive adhesives, polyvinylpyrrolidone pressure sensitive adhesives, polyacrylamide pressure sensitive adhesives, and cellulose pressure sensitive adhesives.

Among these pressure-sensitive adhesives, those which are excellent in optical transparency, exhibit moderate wettability, cohesiveness and adhesive adhesion properties, and are excellent in weather resistance, heat resistance, and the like are preferably used. As showing such a characteristic, an acrylic adhesive is used preferably.

An acrylic adhesive uses the acrylic polymer which has a monomer unit of (meth) acrylic-acid alkylester as a main skeleton as a base polymer. In addition, (meth) acrylic-acid alkylester refers to an alkyl acrylate and / or an alkyl methacrylate, and has the same meaning as (meth) of this invention. As a (meth) acrylic-acid alkylester which comprises the main skeleton of an acryl-type polymer, the C2-C18 thing of a linear or branched alkyl group can be illustrated. For example, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isomyristyl (meth) acrylate, (meth ) Lauryl acrylate and the like. As the (meth) acrylic acid alkyl ester, an acrylic acid alkyl ester having a branched alkyl group is particularly preferable. For example, 2-ethylhexyl acrylate, isooctyl acrylate, isononyl acrylate, isomyristyl acrylate and the like are preferably used.

In the said acrylic polymer, one or more types of copolymerization monomers can be introduce | transduced by copolymerization for the purpose of the improvement of adhesiveness and heat resistance. As a specific example of such a copolymerization monomer, (meth) acrylic-acid 2-hydroxyethyl, (meth) acrylic-acid 2-hydroxypropyl, (meth) acrylic-acid 4-hydroxybutyl, (meth) acrylic acid 6, for example -Hydroxyhexyl, (meth) acrylic acid 8-hydroxyoctyl, (meth) acrylic acid 10-hydroxydecyl, (meth) acrylic acid 12-hydroxylauryl, (4-hydroxymethylcyclohexyl) -methylacrylate, etc. Hydroxyl group-containing monomers; Carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid; Acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; Caprolactone adducts of acrylic acid; Contains sulfonic acid groups, such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamide propanesulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloyloxy naphthalene sulfonic acid Monomers; Phosphoric acid group containing monomers, such as 2-hydroxyethyl acryloyl phosphate, etc. are mentioned.

Furthermore, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylol propane (meth) acrylamide, etc. (N-substituted) amide monomers; Alkyl (meth) acrylate alkylaminoalkyl monomers such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate and t-butylaminoethyl (meth) acrylate; Alkoxy (meth) acrylate alkyl monomers, such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide, N Succinimide type monomers, such as acryloyl morpholine, etc. are mentioned as a monomer example.

In addition, as modified monomers, vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole Vinyl monomers such as vinyl oxazole, vinyl morpholine, N-vinyl carboxylic acid amides, styrene, α-methyl styrene and N-vinyl caprolactam; Cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; Glycol-based acrylic ester monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate; Acrylic ester ester monomers, such as (meth) acrylic acid tetrahydrofurfuryl, fluorine (meth) acrylate, silicone (meth) acrylate, and 2-methoxyethyl acrylate, can also be used.

Among these, a hydroxyl group containing monomer and a carboxyl group containing monomer are used suitably as an optical film use from the point of adhesiveness with respect to a liquid crystal cell, and durability. These monomers become a reaction point with a crosslinking agent.

Although the ratio of the said copolymerization monomer in an acryl-type polymer in particular is not restrict | limited, It is preferable that it is about 0-30%, Furthermore, about 0-15% in the weight ratio of all the constituent monomers.

The average molecular weight of the acrylic polymer is not particularly limited, but the weight average molecular weight is preferably about 300,000 to 2.5 million. The acrylic polymer can be produced by various known methods, and for example, a radical polymerization method such as a bulk polymerization method, a solution polymerization method or a suspension polymerization method can be appropriately selected. As a radical polymerization initiator, various well-known thing of azo type and a peroxide type can be used. Reaction temperature is about 50-80 degreeC normally, and reaction time is 1 to 8 hours. Moreover, the solution polymerization method is preferable among the said manufacturing methods, and ethyl acetate, toluene, etc. are generally used as a solvent of an acryl-type polymer. The solution concentration is usually about 20 to 80% by weight.

As the base polymer of the rubber-based adhesive, for example, natural rubber, isoprene-based rubber, styrene-butadiene-based rubber, recycled rubber, polyisobutylene-based rubber, styrene-isoprene-styrene-based rubber, styrene-butadiene-styrene-based rubber, etc. Can be mentioned. Examples of the base polymer of the silicone pressure-sensitive adhesive include dimethyl polysiloxane, diphenyl polysiloxane, and the like, and examples of these base polymers may include those in which functional groups such as carboxyl groups are introduced.

Moreover, it is preferable to make the said adhesive into the adhesive composition containing a crosslinking agent. As a polyfunctional compound which can be mix | blended with an adhesive, an organic type crosslinking agent and a polyfunctional metal chelate are mentioned. Examples of the organic crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, an imine crosslinking agent, a peroxide-based crosslinking agent, and the like. These crosslinking agents can be used 1 type or in combination of 2 or more types. As an organic type crosslinking agent, an isocyanate type crosslinking agent is preferable. A polyfunctional metal chelate is a thing in which a polyvalent metal is covalently bonded or coordinated with an organic compound. Examples of the polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. have. Examples of the atoms in the organic compound covalently or coordinating include oxygen atoms, and examples of the organic compound include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, ketone compounds, and the like.

Although the compounding ratio of a base polymer, such as an acryl-type polymer, and a crosslinking agent is not specifically limited, Usually, about 0.001-20 weight part of crosslinking agents (solid content) is preferable with respect to 100 weight part of base polymers (solid content), and about 0.01-15 weight part More preferred.

Further, the pressure-sensitive adhesive, if necessary, fillers, pigments, colorants, fillers, antioxidants, ultraviolet absorbers, silane coupling agents, etc., including tackifiers, plasticizers, glass fibers, glass beads, metal powder, and other inorganic powders. Various additives can also be used suitably within the range which does not deviate from the objective of this invention. Moreover, it is good also as an adhesive layer etc. which contain microparticles | fine-particles and show light diffusivity.

As an additive, a silane coupling agent is preferable, About 0.001-10 weight part of silane coupling agents (solid content) is preferable with respect to 100 weight part of base polymers (solid content), It is more preferable to mix | blend about 0.005-5 weight part. . As a silane coupling agent, what is conventionally known can be used without a restriction | limiting in particular. For example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimeth Epoxy-group-containing silane coupling agents such as oxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3 Amino-group-containing silane coupling agents, such as -dimethyl butylidene) propylamine, (meth) acryl-group-containing silane coupling agents, such as 3-acryloxypropyl trimethoxysilane and 3-methacryloxypropyl triethoxysilane, 3- Isocyanate group containing silane coupling agents, such as isocyanate propyl triethoxysilane, can be illustrated.

As an optical film used for the optical film with an adhesive of this invention, what is used for formation of image display apparatuses, such as a liquid crystal display device, is used, The kind in particular is not restrict | limited. As an optical film, application to what has stretched films, such as a polarizing plate and a retardation plate, is preferable.

As for a polarizing plate, what has a transparent protective film on one side or both sides of a polarizer is generally used. A polarizer is not specifically limited, Various things can be used. As the polarizer, for example, a dichroic substance of iodine or a dichroic dye is adsorbed onto hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymerized partial soap films. The polyene type orientation film, such as the thing uniaxially stretched, the dehydration process of polyvinyl alcohol, and the dehydrochlorination process of polyvinyl chloride, etc. are mentioned. Among these, the polarizer which consists of dichroic substances, such as a polyvinyl alcohol-type film and iodine, is preferable. Although the thickness in particular of these polarizers is not restrict | limited, Usually, it is about 5-80 micrometers.

The polarizer which uniaxially stretched the polyvinyl alcohol-type film by iodine, for example, can be manufactured by dyeing polyvinyl alcohol by immersing it in the aqueous solution of iodine, and extending | stretching 3 to 7 times the original length. It can also be immersed in aqueous solution, such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride, etc. as needed. If necessary, the polyvinyl alcohol-based film may be dipped in water and washed with water before dyeing. In addition to washing the polyvinyl alcohol-based film with water, the contamination of the polyvinyl alcohol-based film with the antiblocking agent can be washed, and the polyvinyl alcohol-based film is swelled to prevent nonuniformity such as staining. Stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be dyed with iodine after stretching. It can extend | stretch also in aqueous solution, such as boric acid and potassium iodide, or a water bath.

As a material which forms the transparent protective film formed on one side or both sides of the said polarizer, it is preferable that it is excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene and acrylonitrile styrene copolymer Styrene-type polymers, such as (AS resin), a polycarbonate polymer, etc. are mentioned. Also, polyethylene, polypropylene, polyolefins having a cyclo-norbornene structure, polyolefin-based polymers such as ethylene-propylene copolymers, amide-based polymers such as vinyl chloride-based polymers, nylon and aromatic polyamides, imide-based polymers, and sulfides Phone polymer, polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, allylate polymer, polyoxymethylene polymer, Epoxy-based polymers, blends of the polymers, and the like are also examples of polymers forming the transparent protective film. The transparent protective film can also be formed as a cured layer of a thermosetting or ultraviolet curing resin such as acrylic, urethane, acrylic urethane, epoxy, silicone or the like.

Further, the polymer film described in Japanese Unexamined Patent Publication No. 2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substituted side chain And / or a resin composition containing a thermoplastic resin having unsubstituted phenyl and a nitrile group. As a specific example, the film of the resin composition containing the alternating copolymer which consists of isobutylene and N-methyl maleimide, and an acrylonitrile styrene copolymer is mentioned. As a film, the film which consists of a mixed extrusion product of a resin composition, etc. can be used.

Although the thickness of a protective film can be suitably determined, it is generally 1-500 micrometers in terms of workability, thin film property, etc., such as strength and handleability. In particular, 5-200 micrometers is preferable.

In addition, it is preferable that the protective film be as free as possible. Therefore, the phase difference in the film thickness direction represented by Rth = [(nx + ny) / 2-nz] · d (where nx and ny are the main refractive indices in the film plane, nz is the refractive index in the film thickness direction and d is the film thickness). A protective film having a thickness of -90 nm to +75 nm is preferably used. By using the thing whose phase difference value Rth of such a thickness direction is -90 nm-+75 nm, coloring (optical coloring) of the polarizing plate resulting from a protective film can be almost eliminated. As for thickness direction retardation Rth, More preferably, -80 nm-+60 nm, Especially -70 nm-+45 nm are preferable.

As a protective film, cellulose polymers, such as a triacetyl cellulose, are preferable at the point of polarization characteristic, durability, etc. In particular, a triacetyl cellulose film is preferable. In addition, when forming protective films on both sides of a polarizer, the protective film which consists of the same polymer material may be used in the front and back, and the protective film which consists of another polymer material etc. may be used. The polarizer and the protective film are usually in close contact with an aqueous adhesive or the like. As an aqueous adhesive agent, an isocyanate adhesive, a polyvinyl alcohol adhesive, a gelatin adhesive, a vinyl latex type, an aqueous polyurethane, an aqueous polyester, etc. can be illustrated.

The surface which does not adhere | attach the polarizer of the said transparent protective film may be the thing which performed the process for the purpose of a hard-coat layer, antireflective processing, sticking prevention, and diffusion | diffusion or antiglare.

The hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate, and the like, for example, adding a cured film having excellent hardness and sliding properties by suitable UV-curable resins such as acrylic and silicone to the surface of the transparent protective film. It can form by a system etc. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the prior art. In addition, a sticking prevention process is performed in order to prevent adhesion with the adjacent layer of another member.

In addition, antiglare treatment is performed for the purpose of preventing external light from being reflected on the surface of the polarizing plate and impairing the visibility of the transmitted light of the polarizing plate. For example, the sandblasting method or the embossing method of the roughening method or the transparent fine particles It can form by providing a fine uneven structure to the surface of a transparent protective film by a suitable method, such as a compounding method. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include, for example, a conductive material composed of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, or the like having an average particle diameter of 0.5 to 50 µm. Transparent fine particles such as organic fine particles (containing beads) made of inorganic fine particles, crosslinked or uncrosslinked polymers, and the like are used. When forming a surface fine uneven structure, the use amount of microparticles | fine-particles is about 2-50 weight part generally with respect to 100 weight part of transparent resin which forms a surface fine uneven structure, and 5-25 weight part is preferable. The antiglare layer may also serve as a diffusion layer (visual magnification function, etc.) for diffusing the polarizing plate transmitted light to enlarge the time and the like.

The antireflection layer, the anti-sticking layer, the diffusion layer, the antiglare layer, and the like can be formed on the transparent protective film itself, and can also be formed separately from the transparent protective film as an optical layer.

Moreover, as an optical film, formation of liquid crystal display devices, such as a reflecting plate, a semi-transmissive plate, a retardation plate (including wavelength plates, such as 1/2 or a quarter), a visual compensation film, a brightness enhancement film, etc. The thing used as the optical layer which may be used for is mentioned. These can be used independently as an optical film, and can be laminated | stacked on the said polarizing plate at the time of practical use, and can use 1 layer or 2 or more layers.

Particularly, a reflection type polarizing plate or a semi-transmissive polarizing plate in which a reflecting plate or a semi-transmissive reflecting plate is further laminated on a polarizing plate, an elliptically polarizing plate or circular polarizing plate in which a phase difference plate is further laminated on a polarizing plate, and an optical compensation film laminated on the polarizing plate The polarizing plate in which a brightness improving film is further laminated | stacked on a viewing angle polarizing plate or a polarizing plate is preferable.

The reflective polarizer is formed by forming a reflective layer on the polarizer and is used to form a liquid crystal display device of a type that reflects and displays incident light from the viewing side (display side). It has advantages such as easy thinning of the liquid crystal display device. Formation of a reflective polarizing plate can be performed by a suitable method, such as the method of laying a reflective layer which consists of metal etc. on one surface of a polarizing plate through a transparent protective layer etc. as needed.

As a specific example of a reflection type polarizing plate, what provided the reflecting layer by laying the foil and vapor deposition film which consist of reflective metals, such as aluminum, on one surface of the transparent protective film which carried out the mat process as needed. Moreover, what contains microparticles | fine-particles in the said transparent protective film to make surface fine concavo-convex structure, and has a reflective layer of a fine concavo-convex structure on it, etc. are mentioned. The above-described reflective layer of the fine concave-convex structure has an advantage of preventing incident light from being diffused by diffused reflection by diffuse reflection to prevent unevenness of light and dark. In addition, the fine particle-containing protective film also has the advantage that the incident light and the reflected light are diffused when passing therethrough and the contrast of light and shade can be suppressed. The formation of the reflective layer of the finely uneven structure reflecting the surface finely uneven structure of the transparent protective film, for example, by applying a metal to the surface of the transparent protective layer in a suitable manner such as vacuum deposition method, ion plating method, sputtering method or plating method. This can be done by a direct laying method or the like.

Instead of the method of directly applying to the transparent protective film of the above-mentioned polarizing plate, a reflecting plate can also be used as a reflecting sheet etc. which form a reflecting layer in the suitable film based on the said transparent film. In addition, since the reflective layer is usually made of a metal, the use mode in which the reflective surface is covered with a transparent protective film, a polarizing plate, or the like, can prevent the reduction of the reflectance by oxidation, and furthermore, the long-term sustained surface of the initial reflectance, It is preferable at the point of avoiding the separate laying of the protective layer.

In addition, a semi-transmissive polarizing plate can be obtained by making it the semi-transmissive reflective layer, such as the half-mirror which reflects light in the reflective layer, and permeate | transmits in the above. The transflective polarizing plate is usually formed on the back side of the liquid crystal cell, and when using a liquid crystal display device or the like in a relatively bright atmosphere, reflects incident light from the viewing side (display side) to display an image, and in a relatively dark atmosphere, A liquid crystal display device of a type for displaying an image and the like can be formed using a built-in power supply such as a backlight built in the backside of the transflective polarizing plate. That is, the transflective polarizing plate can save energy of using a light source such as a backlight in a bright atmosphere, and is useful for forming a liquid crystal display device of the type that can be used using a built-in power supply even in a relatively dark atmosphere.

An elliptical polarizing plate or circular polarizing plate in which a retardation plate is further laminated on the polarizing plate will be described. A retardation plate or the like is used to change linearly polarized light into elliptical polarization or circularly polarized light, to change elliptical polarization or circularly polarized light into linearly polarized light, or to change the polarization direction of linearly polarized light. In particular, a so-called quarter wave plate (also referred to as λ / 4 plate) is used as a phase difference plate for converting linearly polarized light into circularly polarized light or for converting circularly polarized light into linearly polarized light. A half wave plate (also called a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

The elliptical polarizing plate is effectively used for compensating (preventing) the coloration (blue or yellow color) caused by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device, and for displaying a black and white display without the coloration. In addition, it is preferable to control the three-dimensional refractive index because the coloring degree generated when the screen of the liquid crystal display device is viewed in the oblique direction can be prevented (prevented). The circular polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflection type liquid crystal display device in which an image becomes color display, and also has an antireflection function.

As a retardation plate, the birefringent film formed by carrying out uniaxial or biaxial stretching process of a polymeric material, the orientation film of a liquid crystal polymer, the thing which supported the orientation layer of a liquid crystal polymer with a film, etc. are mentioned. Although the thickness of a retardation plate is not specifically limited, either, about 20-150 micrometers is common.

Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyallylate, Polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyphenylene sulfide, polyphenylene oxide, polyallyl sulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose polymer, norbornene-based resin, Or these binary or ternary various copolymers, graft copolymers, blends and the like. These polymeric raw materials become an orientation substance (stretched film) by extending | stretching etc.

Examples of the liquid crystal polymer include various main chain or side chains in which a conjugated linear atomic group (mesogen) for imparting liquid crystal orientation is introduced into the main chain or side chain of the polymer. As a specific example of a main-chain liquid crystal polymer, the nematic oriented polyester liquid crystalline polymer, the discotic polymer, the cholesteric polymer, etc. of the structure which couple | bonded the mesogenic group in the spacer part which provides flexibility are mentioned, for example. Can be. Specific examples of the side chain type liquid crystal polymer include a polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton and a side chain spacer part composed of a conjugated atomic group interposed therebetween. The thing which has the mesogenic part which consists of substituted cyclic compound units, etc. are mentioned. These liquid crystal polymers are, for example, a solution of a liquid crystalline polymer on an orientation treatment surface such as a rubbing treatment of a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or a vapor deposition of silicon oxide. It is performed by expanding and heat-treating.

The retardation plate may have a suitable retardation according to the purpose of use, for example, for the purpose of compensating coloring or vision due to birefringence of various wavelength plates and liquid crystal layers, or by laminating two or more kinds of retardation plates. The thing which controlled optical characteristics, such as a phase difference, may be sufficient.

In addition, said elliptical polarizing plate and reflective elliptical polarizing plate laminate | stack a polarizing plate or a reflective polarizing plate, and a phase difference plate in a suitable combination. Such elliptical polarizing plates and the like can be formed by sequentially stacking them separately in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflective) polarizing plate and a retardation plate, but such an optical film such as an elliptical polarizing plate in advance. Since it is excellent in the stability of quality, lamination | stacking workability, etc., there exists an advantage which can improve manufacturing efficiency, such as a liquid crystal display device.

The visual compensation film is a film for enlarging the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from the direction slightly tilted rather than perpendicular to the screen. Such a visually compensated retardation plate consists of, for example, supporting an alignment layer such as a liquid crystal polymer on an alignment film such as a retardation plate or a liquid crystal polymer or a transparent substrate. A conventional retardation plate is a polymer film having birefringence stretched biaxially in the plane direction, whereas a polymer film having birefringence stretched uniaxially in the plane direction is used. Or a bidirectional stretched film such as a birefringent polymer or a diagonally oriented film used to control the refractive index in the thickness direction, which is uniaxially stretched in the plane direction and also stretched in the thickness direction. As a diagonal orientation film, the thing which carried out the extending | stretching process and / or shrinkage treatment of the polymer film under the effect of the shrinkage force by heating, for example adhere | attaching a heat shrink film to a polymer film, the thing which carried out the diagonal orientation of the liquid crystal polymer, etc. are mentioned. . The raw material polymer of the retardation plate is the same as the polymer described in the above retardation plate, and is used for the purpose of preventing the coloring due to the change of the viewing angle based on the phase difference by the liquid crystal cell, or the expansion of the viewing angle of the good visibility. A suitable one can be used.

In addition, in order to achieve a wide viewing angle of good visibility, an optical compensation retardation plate supporting an optically anisotropic layer composed of an alignment layer of a liquid crystal polymer, particularly an inclined alignment layer of a discotic liquid crystal polymer, with a triacetyl cellulose film can be preferably used. have.

The polarizing plate with a polarizing plate and a brightness enhancing film is usually formed on the back side of the liquid crystal cell and used. The brightness enhancement film exhibits a property of reflecting linearly polarized light on a predetermined polarization axis or circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmitting other light. The polarizing plate laminated | stacked with the polarizing plate injects light from a light source, such as a backlight, and acquires the transmitted light of a predetermined polarization state, and reflects the light other than the said predetermined polarization state without transmitting. The light reflected from the surface of the brightness enhancing film is inverted again through a reflecting layer or the like formed on the rear side and reincident to the brightness enhancing film, and a part or all of the light is transmitted as light in a predetermined polarization state to increase the amount of light that passes through the brightness enhancing film. In addition, the luminance can be improved by supplying polarized light that is hardly absorbed by the polarizer and increasing the amount of light that can be used for liquid crystal display image display. That is, when light is incident from the back side of the liquid crystal cell through a backlight or the like without using a brightness enhancing film, most of the light having a polarization direction that does not coincide with the polarization axis of the polarizer is absorbed by the polarizer, It does not penetrate. That is, although it changes also with the characteristic of the polarizer used, about 50% of light is absorbed by a polarizer, and the quantity of light which can be used for a liquid crystal image display etc. by that amount reduces, and an image becomes dark. The brightness enhancement film repeatedly reflects the light having the polarization direction absorbed by the polarizer in the brightness enhancement film without incident on the polarizer, inverts it through a reflecting layer or the like formed on the rear side thereof, and reenters the brightness enhancement film. Since only the polarization direction in which the polarization direction of the light reflected and inverted between the two polarization directions can pass through the polarizer is transmitted through the luminance enhancement film and is supplied to the polarizer, light of the backlight or the like can be efficiently transferred to the image of the liquid crystal display device. We can use for display and can brighten screen.

A diffusion plate may be formed between the brightness enhancing film and the reflective layer. The light in the polarization state reflected by the brightness enhancement film is directed toward the reflection layer or the like, but the diffuser plate provided uniformly diffuses the light passing therethrough and at the same time eliminates the polarization state and becomes a non-polarization state. That is, the light in a natural light state is reflected toward a reflection layer, etc., is reflected through a reflection layer, etc., and it passes through a diffuser plate again, and re-injects into a brightness enhancement film. Thus, by forming a diffuser plate that returns the polarized light to the original natural light between the brightness enhancing film and the reflecting layer, the brightness of the display screen is maintained, and the unevenness of the brightness of the display screen is reduced. Can provide. By forming such a diffusion plate, it is thought that the first incident light can increase the number of times of reflection repetition appropriately and can provide a uniform bright display screen in harmony with the diffusion function of the diffusion plate.

As said brightness improving film, it is a cholesteric which shows the characteristic which permeate | transmits linearly polarized light of a predetermined polarization axis, and reflects other light, such as the multilayered laminated film of a dielectric material, and the multilayered laminated body of the thin film film from which refractive index anisotropies differ, Suitable ones, such as those in which the circularly polarized light of either one of left rotation and right rotation are reflected and other light transmits, such as an alignment film of the liquid crystal polymer and the alignment liquid crystal layer supported on the film substrate, can be used.

Therefore, in the brightness improvement film of the type which permeate | transmits linearly polarized light of the said predetermined polarization axis, it can transmit efficiently, suppressing the loss of absorption by a polarizing plate by making the transmitted light into a polarizing plate as it enters with a polarizing axis. In addition, in the luminance improvement film of the type which transmits circularly polarized light, such as a cholesteric liquid crystal layer, although it may be made to enter into a polarizer as it is, in view of suppressing absorption loss, the circularly polarized light is linearly polarized through a phase difference plate, It is preferable to make it incident. In addition, by using a quarter wave plate as the retardation plate, circularly polarized light can be converted into linearly polarized light.

A retardation plate functioning as a quarter wave plate at a wide wavelength such as visible light is, for example, a phase difference layer exhibiting retardation characteristics different from a retardation plate functioning as a quarter wave plate with respect to pale color light having a wavelength of 550 nm. For example, it can obtain by the method of superimposing the retardation layer which functions as a 1/2 wave plate. Therefore, the phase difference plate arrange | positioned between a polarizing plate and a brightness improving film may consist of one layer or two or more phase difference layers.

Also, with respect to the cholesteric liquid crystal layer, by arranging two or three or more layers in a combination of different reflection wavelengths, it is possible to obtain circularly polarized light reflected in a wide wavelength range such as visible light. Based on this, transmission circularly polarized light in a wide wavelength range can be obtained.

In addition, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers like the polarization splitting polarizing plate. Therefore, the reflective elliptical polarizing plate, the semi-transparent elliptical polarizing plate, etc. which combined said reflective polarizing plate, a semi-transmissive polarizing plate, and a phase difference plate may be sufficient.

Although the optical film which laminated | stacked the said optical layer on the polarizing plate can also be formed by the method of separately laminating | stacking sequentially in the manufacturing process of a liquid crystal display device, etc., what laminated | stacked previously was made into the optical film, such as stability of a quality, assembly work, etc. It is excellent in this and there exists an advantage which can improve manufacturing processes, such as a liquid crystal display device. Suitable lamination means such as an adhesive layer can be used for lamination. In adhesion | attachment of the said polarizing plate and another optical layer, these optical axes can be made into a suitable arrangement angle according to the target phase difference characteristic etc ..

Manufacture of the optical film with an adhesive of this invention is performed by forming an adhesive layer in the said optical film. It does not restrict | limit especially as a formation method, The method of apply | coating and drying an adhesive solution, the method of transferring by the release sheet which formed the adhesive layer, etc. are mentioned. Although the thickness of an adhesive layer is not specifically limited, It is good to set it as about 3-100 micrometers, Preferably it is about 10-40 micrometers. In addition, when forming in an adhesive layer, you may form an adhesive layer after forming an antistatic layer.

Examples of the constituent material of the release sheet include synthetic resin films such as paper, polyethylene, polypropylene and polyethylene terephthalate, rubber sheets, paper, cloth, nonwoven fabrics, nets, foam sheets, metal foils, and suitable thin films such as laminates. Can be mentioned. On the surface of a release sheet, in order to improve the peelability from an adhesive layer, the low adhesive peeling process, such as a silicone process, a long chain alkyl process, and a fluorine process, may be performed as needed.

Moreover, in each layer, such as an optical film and an adhesive layer of the optical film with an adhesive of this invention, a salicylic acid ester type compound, a benzophenol type compound, a benzotriazole type compound, a cyanoacrylate type compound, a nickel complex salt type compound, for example It may be made to have ultraviolet absorbing ability by a method such as treatment with a ultraviolet absorber such as.

The optical film with an adhesive of this invention can be used suitably for formation of various image display apparatuses, such as a liquid crystal display device. Formation of a liquid crystal display device can be performed according to the prior art. In other words, a liquid crystal display device is generally formed by appropriately assembling a component such as a liquid crystal cell, an optical film with pressure-sensitive adhesive, and a lighting system, if necessary, incorporating a driving circuit or the like. There is no restriction | limiting in particular except using, and it can follow conventionally. Also about a liquid crystal cell, TN type, STN type, (pi) type, etc. arbitrary types can be used, for example.

Suitable liquid crystal display devices, such as the liquid crystal display device which arrange | positioned the optical film with an adhesive on one side or both sides of a liquid crystal cell, and the thing which used the backlight or the reflecting plate for the illumination system can be formed. In that case, the optical film by this invention can be provided in one or both sides of a liquid crystal cell. When forming an optical film in both sides, these may be the same and may differ. In the formation of the liquid crystal display device, for example, a diffuser plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, or a suitable component at a suitable position may be one or two layers. You can place more than that.

Next, the organic electroluminescent device (organic EL display device) will be described. The optical film (polarizing plate, etc.) of this invention is applicable also to an organic electroluminescence display. In general, an organic EL display device forms a light emitting body (organic electroluminescent light emitting body) by sequentially stacking a transparent electrode, an organic light emitting layer, and a metal electrode on a transparent substrate. Here, an organic light emitting layer is a laminated body of various organic thin films, For example, the laminated body of the hole injection layer which consists of triphenylamine derivatives, etc., and the light emitting layer which consists of fluorescent organic solids, such as anthracene, or such a light emitting layer, The structure which has various combinations, such as the laminated body of the electron injection layer which consists of a rylene derivative, etc., or these laminated bodies of a hole injection layer, a light emitting layer, and an electron injection layer is known.

In the organic EL display, holes and electrons are injected into the organic light emitting layer by applying a voltage to the transparent electrode and the metal electrode, and energy generated by the recombination of the holes and the electrons excites the fluorescent material, and the excited fluorescent material is in a ground state. The light is emitted on the principle of emitting light when returning to. The mechanism of intermediate recombination is the same as that of a general diode, and as can be expected from this, the current and the light emission intensity show strong nonlinearity accompanied by rectification with respect to the applied voltage.

In the organic EL display device, at least one electrode must be transparent in order to induce light emission from the organic light emitting layer, and a transparent electrode formed of a transparent conductor such as indium tin oxide (ITO) is usually used as an anode. In addition, in order to facilitate electron injection and improve luminous efficiency, it is important to use a material having a small work function for the cathode, and metal electrodes such as Mg-Ag and Al-Li are usually used.

In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer also transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate during non-emission, and is transmitted through the transparent electrode and the organic light emitting layer and reflected from the metal electrode again exits to the surface side of the transparent substrate. The display surface of the device looks like a mirror.

An organic EL display device comprising an organic electroluminescent emitter comprising a transparent electrode on the front side of an organic light emitting layer that emits light by application of a voltage and a metal electrode on the back side of the organic light emitting layer. While forming a polarizing plate on the surface side of an electrode, a phase difference plate can be formed between these transparent electrodes and a polarizing plate.

Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected from the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, when the phase difference plate is constituted by a quarter wave plate and the angle between the polarization direction between the polarizing plate and the phase difference plate is adjusted to π / 4, the mirror surface of the metal electrode can be completely shielded.

That is, only the linearly polarized light component transmits external light incident on the organic EL display device by the polarizing plate. This linearly polarized light is generally elliptically polarized by the retardation plate. In particular, when the retardation plate is a quarter wave plate and the angle between the polarizing plate and the retardation plate is? / 4, the circularly polarized light is circularly polarized.

The circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, and is reflected by the metal electrode. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

Example

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples. In addition, in each example, both part and% are based on a weight.

(Measurement of Tg of Adhesive Layer)

Tg of the adhesive layer was calculated | required by the DSC method. Tg was made into the starting temperature. The measuring apparatus used is a DSC6220 type differential scanning calorimeter manufactured by Seiko Instruments.

(Measurement of Strength (F) attributable to Thermal Stress of Optical Film)

F = α · ΔT · E · l · h

(Where α is the thermal expansion coefficient at -60 to 23 ° C, ΔT is the temperature difference based on 23 ° C, E is the elastic modulus, l is the width, and h is the thickness)

Obtained by The coefficient of thermal expansion (α) was obtained by the TMA method. The measuring apparatus used was a TMA / SS6100 thermomechanical analyzer manufactured by Seiko Instruments. Elastic modulus (E) was calculated | required by the tension test by Autograph AG-1 by Shimadzu Corporation. l * h is the cross-sectional area of an optical film.

Example 1

In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirring device, 99.9 parts of oxocyl acrylate, 0.1 part of 2-hydroxyethyl acrylate, and 0.3 part of 2,2'-azobisisobutyronitrile are ethyl acetate. The mixture was added together and reacted at 60 ° C. under nitrogen gas for 4 hours, and then ethyl acetate was added to the reaction solution to obtain an acrylic polymer solution having a solid content concentration of 30% (1.6 million weight average molecular weight of the acrylic polymer). 0.15 part of trimethylol-propantolylene diisocyanate and 0.01 part of 3-glycidoxy propyl trimethoxysilane were mix | blended per 100 parts of solid content of the said solution, and the acrylic adhesive was obtained. Subsequently, the said acrylic adhesive was coated to the separator which consists of a polyester film surface-treated with the silicone type peeling agent, and it heat-processed at 150 degreeC for 5 minutes, and obtained the adhesive layer of 20 micrometers in thickness. It was -62 degreeC when Tg of the said adhesive layer was measured.

The pressure-sensitive adhesive layer was transferred to one side of the polarizing plate (NPF-SEG5224DU, manufactured by Nitto Electric Industries, Ltd.) to obtain an optical film with a pressure-sensitive adhesive. Then, the said polarizing plate with an adhesive layer was bonded by the laminator to the 280 mm x 280 mm size alkali free glass plate, it was left to stand in 50 degreeC and 5 atmospheres of autoclaves for 15 minutes, and was fully crimped.

The coefficient of thermal expansion α = 5.3 × 10 ⁻⁵ (1 / ° C.), modulus of elasticity = 3.05 × 10 ⁹ kPa, thickness = 185 μm and width = 270 mm with respect to the stretching axis of the polarizing plate at 0 ° C. As a result of calculating the strength F by heat shrink, it was F = 186N.

Example 2

In the same manner as in Example 1, an adhesive layer having a thickness of 20 μm was obtained. The pressure-sensitive adhesive layer was transferred to one side of the polarizing plate (NPF-TEG5465DU, manufactured by Nitto Electric Industries, Ltd.), to obtain an optical film with pressure-sensitive adhesive. Then, the said polarizing plate with an adhesive layer was bonded by the laminator to the 280 mm x 280 mm size alkali free glass plate, it was left to stand in 50 degreeC and 5 atmospheres of autoclaves for 15 minutes, and was fully crimped.

The coefficient of thermal expansion α = 5.3 × 10 ⁻⁵ (1 / ° C.), modulus of elasticity = 3.6 × 10 ⁹ Pa, thickness = 105 μm, width = 270 mm in the 90 ° direction with respect to the stretching axis of the polarizing plate, at 0 ° C. As a result of calculating the strength F by heat shrink, it was F = 124N.

Example 3

99.9 parts of 2-ethylhexyl acrylate, 0.1 parts of 2-hydroxyethyl acrylate, and 0.3 parts of 2,2'-azobisisobutyronitrile to a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirring device After adding together with ethyl and reacting for 4 hours at 60 ° C. under a nitrogen gas stream, ethyl acetate was added to the reaction solution to obtain an acrylic polymer solution having a solid content concentration of 30% by weight (1.7 million weight average molecular weight of the acrylic polymer). . 0.15 part of trimethylol-propantolylene diisocyanate and 0.01 part of 3-glycidoxy propyl trimethoxysilane were mix | blended per 100 parts of solid content of the said solution, and the acrylic adhesive was obtained. Next, the said acrylic adhesive was coated to the separator which consists of a polyester film surface-treated with the silicone type peeling agent, and it heat-processed at 150 degreeC for 5 minutes, and obtained the adhesive layer of 20 micrometers in thickness. It was -60 degreeC when Tg of the said adhesive layer was measured.

The pressure-sensitive adhesive layer was transferred to one side of the polarizing plate (NPF-SEG5224DU, manufactured by Nitto Electric Industries, Ltd.) to obtain an optical film with a pressure-sensitive adhesive. Then, the said polarizing plate with an adhesive layer was bonded by the laminator to the 280 mm x 280 mm size alkali free glass plate, it was left to stand in 50 degreeC and 5 atmospheres of autoclaves for 15 minutes, and was fully crimped.

Example 4

In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirring device, 99 parts of butyl acrylate, 1 part of 4-hydroxyethyl acrylate, and 0.3 part of 2,2'-azobisisobutyronitrile together with ethyl acetate After addition and making it react for 4 hours at 60 degreeC under nitrogen gas airflow, ethyl acetate was added to the reaction liquid, and the acrylic polymer solution (weight average molecular weight 1.65 million of acrylic polymer) of 30 weight% of solid content concentration was obtained. 0.3 part dibenzoyl peroxide, 0.02 part trimethylol propane xylylene diisocyanate, and 0.2 part 3-glycidoxy propyl trimethoxysilane were mix | blended per 100 parts of solid content of this solution, and the acrylic adhesive was obtained. Subsequently, the said acrylic adhesive was coated to the separator which consists of a polyester film surface-treated with the silicone type peeling agent, and it heat-processed at 155 degreeC for 3 minutes, and obtained the adhesive layer of thickness 20micrometer. It was -38 degreeC when Tg of the said adhesive layer was measured.

The pressure-sensitive adhesive layer was transferred to one side of the polarizing plate (NPF-SEG5224DU, manufactured by Nitto Electric Industries, Ltd.) to obtain an optical film with a pressure-sensitive adhesive. Then, the said polarizing plate with an adhesive layer was bonded by the laminator to the 280 mm x 280 mm size alkali free glass plate, it was left to stand in 50 degreeC and 5 atmospheres of autoclaves for 15 minutes, and was fully crimped.

Comparative Example 1

In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirring device, 95 parts of butyl acrylate, 5 parts of acrylic acid, and 0.3 parts of 2,2'-azobisisobutyronitrile were added together with ethyl acetate to provide a nitrogen gas stream. After reacting at 60 degreeC for 4 hours, ethyl acetate was added to this reaction liquid, and the acrylic polymer solution (weight average molecular weight 2 million of acrylic polymer) of 30 weight% of solid content concentration was obtained. 0.6 parts of trimethylol-propantolylene diisocyanate and 0.075 parts of 3-glycidoxy propyl trimethoxysilane were mix | blended per 100 parts of solid content of the said solution, and the acrylic adhesive was obtained. Subsequently, the said acrylic adhesive was coated to the separator which consists of a polyester film surface-treated with the silicone type peeling agent, and it heat-processed at 150 degreeC for 5 minutes, and obtained the adhesive layer of 20 micrometers in thickness. It was -30 degreeC when Tg of the said adhesive layer was measured.

The pressure-sensitive adhesive layer was transferred to one side of the polarizing plate (NPF-SEG5224DU, manufactured by Nitto Electric Industries, Ltd.) to obtain an optical film with a pressure-sensitive adhesive. Then, the said polarizing plate with an adhesive layer was bonded by the laminator to the 280 mm x 280 mm size alkali free glass plate, it was left to stand in 50 degreeC and 5 atmospheres of autoclaves for 15 minutes, and it fully crimped | bonded.

Comparative Example 2

In the same manner as in Comparative Example 1, an adhesive layer having a thickness of 20 μm was obtained. The pressure-sensitive adhesive layer was transferred to one side of the polarizing plate (NTO-TEG Corporation, NPF-TEG5465DU) used in Example 2 to obtain an optical film with pressure-sensitive adhesive. Then, the said polarizing plate with an adhesive layer was bonded by the laminator to the 280 mm x 280 mm size alkali free glass plate, it was left to stand in 50 degreeC and 5 atmospheres of autoclaves for 15 minutes, and was fully crimped.

The following evaluation was performed about the optical film with an adhesive obtained by the Example and the comparative example (sample bonded to the alkali free glass plate). The results are shown in Table 1.

<Amount of warpage>

After the sample was treated for 30 minutes in a low temperature region of 0 ° C or less shown in Table 1, the sample was placed on a band free of unevenness horizontally in an atmosphere of 23 ° C and 55% RH, and the warp amount of four in-plane warpages was spaced. Measured using a gauge. The curvature amount was made into the average value of 4 points | pieces. Evaluation criteria are as follows.

(Circle): The curvature of glass is less than 0.5 mm.

(Triangle | delta): The curvature of glass is 0.5-1.0 mm.

X: The curvature of glass exceeds 1.0 mm.

  Tg (℃) of adhesive   Strength of Optical Film (N)  Deflection  0 ℃  -10 ℃  -20 ℃  -30 ℃  -40 ℃  Example 1  -62  186  ○  ○  ○  ○  ○  Example 2  -62  124  ○  ○  ○  ○  ○  Example 3  -60  186  ○  ○  ○  ○  ○  Example 4  -38  186  ○  ○  ○  ○  △  Comparative Example 1  -30  186  ○  △  ×  ×  ×  Comparative Example 2  -30  124  ○  ○  △  ×  ×

Industrial availability

The optical film with an adhesive of this invention is what contains a stretched film as an optical film, and is applicable suitably to image display apparatuses, such as a liquid crystal display device, an organic electroluminescence display, and a PDP.

Claims (5)

delete As an optical film with an adhesive which has an adhesive layer on at least one surface of an optical film, Tg (glass transition temperature) of the said adhesive layer is -35 degrees C or less, The proof strength F attributable to the thermal stress of the optical film is F = α · ΔT · E · l · h (Where α is the thermal expansion coefficient at -60 to 23 ° C, ΔT is the temperature difference based on 23 ° C, E is the elastic modulus, l is the width, and h is the thickness), The said optical film has a stretched film, and the yield strength (F) which generate | occur | produces in 90 degrees with respect to the extending | stretching axis | shaft of the said stretched film at 0 degreeC is 50 N or more, The optical film with an adhesive characterized by the above-mentioned. delete The method of claim 2, The said optical film contains a polarizing plate and / or retardation plate, The optical film with an adhesive characterized by the above-mentioned. delete