JP2000085057A - Optical film laminate - Google Patents

Abstract

(57) [Problem] To provide an optical film laminate suitable for application to an optical element having improved storage reliability and appearance by suppressing peeling and distortion of a film peripheral portion. SOLUTION: An optical film laminate is obtained by bonding an optical film and a transparent plate-like body with a hot melt type adhesive made of polyvinyl acetal (modified polyvinyl alcohol) resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical film laminate obtained by laminating an optical film and a transparent plate.
Particularly, the present invention relates to an optical film laminate suitable for application to an optical element having excellent storage reliability and appearance characteristics by suppressing peeling or distortion of a film peripheral portion.

[0002]

2. Description of the Related Art Conventionally, when an optical film is laminated on a transparent plate such as a glass plate or an acrylic plate, an adhesive is most commonly used from the viewpoint of good workability. However, when laminated with an adhesive, there have been problems such as peeling off at the peripheral portion of the optical film due to environmental changes such as temperature and humidity, and noticeable distortion at the peripheral portion due to deformation of the adhesive.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and in particular, in a laminate in which an optical film and a transparent plate are bonded,
To provide an optical film laminate suitable for use as an optical element having an adhesive layer having optical clarity, capable of reducing peeling and distortion of a film peripheral portion, having excellent workability, and having excellent storage reliability and appearance characteristics. is there.

[0004]

That is, the present invention provides the first aspect.
, An optical film laminate obtained by laminating an optical film and a transparent plate-shaped body, wherein the optical film and the transparent plate-shaped body are bonded together by a hot-melt adhesive made of a polyvinyl acetal resin. About. Secondly, the present invention provides a liquid crystal alignment in which the optical film is formed from a liquid crystal material, and the liquid crystal material is cooled to a liquid crystal transition temperature below the liquid crystal transition point to fix the liquid crystal material. The optical film laminate according to claim 1, which is a film or a laminated film having at least one such film. Thirdly, the present invention provides a liquid crystal alignment in which an optical film is formed from a liquid crystalline substance having photo- or thermal cross-linking properties, and the liquid crystalline substance is fixed in a liquid crystal state by a light or thermal cross-linking reaction. The optical film laminate according to claim 1, which is a film or a laminated film having at least one such film. Fourth, the present invention relates to the first to third optical film laminates described above, wherein a hot-melt adhesive made of polyvinyl acetal resin contains an ultraviolet absorber and / or a light stabilizer. Fifth, the present invention relates to the first to fourth optical film laminates, wherein a corona discharge treatment is applied to an optical film surface in contact with the polyvinyl acetal resin.

Hereinafter, the present invention will be described in detail. The hot melt adhesive used in the present invention is substantially composed of a polyvinyl acetal resin (also referred to as a modified polyvinyl alcohol) obtained by an acetalization reaction between polyvinyl alcohol and various aldehydes. Generally speaking, hot-melt adhesives are generally used by heating and melting without a solvent, but the polyvinyl acetal resin of the present invention can be used in a state of being heated and melted without using a solvent, or in a state of being dissolved in a solvent. It may be used, and its usage is not particularly limited. In particular, it is more preferable to dissolve in a solvent because there are advantages such that the coating step can be performed at a relatively low temperature and compatibility is easily obtained even when an additive is added.

The raw material polyvinyl alcohol is not particularly limited, but has a polymerization degree of 100 to 500.
It is desirable to use those having a saponification degree of 75 to 99.8 mol%. When the degree of polymerization is less than 100, synthesis of polyvinyl alcohol becomes difficult, and conversely, 500
If it exceeds 0, the viscosity of the solution may be too high. When the degree of saponification is less than 75 mol%, the solubility of the polyvinyl acetal resin in the solvent may not be sufficient. On the contrary, when the degree of saponification exceeds 99.8 mol%, the synthesis of polyvinyl alcohol may be difficult. is there. Further, as the polyvinyl alcohol, two or more kinds of polyvinyl alcohols having different degrees of polymerization may be mixed and used, and in that case, it is desirable to use polyvinyl alcohol having an apparent degree of polymerization within the above range.

Aldehydes used for acetalization of polyvinyl alcohol are not particularly limited, and aliphatic aldehydes such as formaldehyde and butyraldehyde, benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, Other alkyl-substituted benzaldehyde, chlorobenzaldehyde, other halogen-substituted benzaldehyde, phenylacetobenzaldehyde, β
-Phenylpropionaldehyde, other phenyl-substituted alkyl aldehydes, and a hydroxy group on the aromatic ring,
An aromatic aldehyde having an alkoxy group, an amino group, a cyano group and the like can be exemplified. These aldehydes may be used alone or in combination of two or more.

[0008] The solvent when the polyvinyl acetal resin is used as a solution is not particularly limited, but in the case of a resin having high hydrophilicity, a mixed solvent of alcohol / water is used.
When the hydrophilicity is low, a mixed solution of alcohol, aromatic, ketone, and ester solvents is usually used. In this case, the alcohol is methanol, ethanol, isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, the aromatic type is toluene, xylene, sorber naphtha, the ketone type is methyl ethyl ketone, methyl isobutyl ketone, and the ester type is acetic acid. Ethyl and the like can be mentioned, and these solvents may be used alone or in combination of two or more.

In the present invention, when a polyvinyl acetal resin is used for bonding an optical film and a transparent plate,
One or more kinds of polyvinyl acetal resins may be used alone, and for the purpose of further improving performance and workability, various other resins, plasticizers, softeners, tackifiers, glass fibers and glass beads Various additives such as a filler composed of inorganic powder, a pigment, a colorant, an ultraviolet absorber, a light stabilizer, and an antioxidant may be added. For example, if a phenol resin, a melamine resin, an epoxy resin, an isocyanate, a dialdehyde, or the like is added to cause a crosslinking reaction, the strength of the coating film and the adhesive strength can be increased. In particular, for applications requiring light resistance, the light resistance can be significantly improved by adding an ultraviolet absorber and / or a light stabilizer. In particular, when light is incident from the transparent plate-like body side, it is extremely effective in improving the light resistance of the optical film. The ultraviolet absorber used here is not particularly limited as long as it is compatible with polyvinyl acetal or can be dispersed in polyvinyl acetal.For example, benzophenone-based, benzotriazole-based, oxalic acid anilide-based, cyanoacrylate-based,
Organic UV absorbers such as triazine and salicylate, and inorganic UV absorbers such as cesium oxide, titanium oxide and zinc oxide can be used. As the light stabilizer, for example, a hindered amine type, a quencher and the like can be used. Here, the ultraviolet absorber and the light stabilizer may be added alone or both may be added simultaneously.

When the additive is added, the amount of the additive is usually 0.0% based on the solid weight of the polyvinyl acetal resin.
1 to 50 parts, preferably 0.05 to 40 parts, more preferably 0.1 to 30 parts. If the amount is less than 0.01 part, the effect of the addition may not be sufficiently recognized. If the amount is more than 50 parts, problems such as a decrease in the adhesion performance of the polyvinyl acetal resin and generation of haze may be caused.

In the present invention, the surface of the optical film in contact with the polyvinyl acetal resin layer (adhesive layer) having a laminated structure of an optical film / polyvinyl acetal resin layer (adhesive layer) / transparent plate is subjected to corona discharge treatment. The adhesive force at the interface can be improved. The corona discharge treatment can be performed by a known method, and the treatment conditions vary depending on the type of the optical film and the corona treatment device to be used.
0 W · mim / m ² is preferable. Also, if necessary,
An undercoat layer may be provided on the surface of the optical film in contact with the polyvinyl acetal resin layer (adhesive layer).

Next, the optical film will be described. In the present invention, the type of the optical film is not particularly limited. Examples of the optical film used in the present invention include a color compensation film, a viewing angle improving film, a retardation film, a hologram film, a polarizing film, a light reflection preventing film, a light reflection film, a light partially reflecting partially transmitting film, and a diffraction grating film. , An interference filter film, a color filter film, a light diffusion film, a light condensing film, a stretched film, a １ ／ wavelength plate, a 波長 wavelength plate, and the like.

The optical film includes: (1) a liquid crystal alignment film composed of a liquid crystalline substance which can be oriented in a state above the liquid crystal transition point and fixed in a glass state below the liquid crystal transition point, or a laminated film having at least one such film. A liquid crystal alignment film comprising a liquid crystalline substance having photo- or thermal cross-linking properties, and a liquid-crystal oriented film in which the liquid crystalline substance is oriented and then photo- or thermal cross-linked to fix the orientation or a laminated film having at least one such film. Optical films are preferred.

Here, the liquid crystalline substance is not particularly limited. For example, nematic liquid crystal, chiral nematic liquid crystal, smectic liquid crystal, chiral smectic liquid crystal, discotic nematic liquid crystal, chiral discotic nematic liquid crystal, discotic columnar liquid crystal, Polymer liquid crystals exhibiting liquid crystal properties such as chiral discotic columnar liquid crystals and low-molecular liquid crystals are exemplified. As the liquid crystal substance, either lyotropic property or thermotropic property can be used, but a substance exhibiting thermotropic property is more preferable in terms of a film forming process and the like.

Examples of the polymer liquid crystal include condensation polymer liquid crystal represented by liquid crystalline polyester, vinyl polymer polymer liquid crystal, polysiloxane polymer liquid crystal, and epoxy polymer liquid crystal. As low-molecular liquid crystals, discotic liquid crystals such as biphenyl derivatives, phenylbenzoate derivatives, stilbene derivatives, and other widely known calamitic (rod-like) liquid crystal compounds, triphenylene derivatives, and tolcene derivatives are known. A compound having a compound or the like as a basic skeleton is exemplified. According to the present invention, an optical film is obtained from the above-described liquid crystalline substance alone or a composition containing at least one or more such substances. When the composition is used, a non-liquid crystalline substance may be added to the composition as long as the composition finally exhibits liquid crystallinity.

Next, a method for producing an optical film having a fixed liquid crystal orientation according to the present invention will be described, but it is needless to say that the present invention is not limited thereto. The liquid crystal alignment film is manufactured by arranging the above liquid crystalline substance on an alignment substrate having alignment ability, forming an alignment in a liquid crystal state, and fixing the alignment form. If the alignment substrate is transparent and can be used optically, it can be used as it is as an optical film. When the alignment substrate is not transparent or has a large optical anisotropy, the desired optical film can be obtained by transferring the liquid crystal alignment film from the alignment substrate to another transparent substrate. .

The alignment substrate is not particularly limited as long as it is a substrate on which a liquid crystalline substance can be aligned. For example, polyimide, polyamide imide, polyamide, polyether imide, polyether ether ketone, polyether Ketone, polyketone sulfide, polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal, polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulose, triacetyl cellulose, Plastic film such as triacetyl cellulose, epoxy resin, phenol resin, etc. Rubbing plastic film and the like which has been subjected to direct rubbing treatment Irumu.

If necessary, a uniaxial or biaxial stretching operation may be applied to the oriented substrate. The support film may be one subjected to a surface treatment such as a hydrophilic treatment or a hydrophobic treatment. In addition, the above-mentioned support film may be used singly, or may be used by laminating two or more films as needed. In addition, as the alignment substrate, use a metal substrate such as aluminum, iron, or copper with a slit-shaped groove on the surface, or a glass substrate such as alkali glass, borosilicate glass, or flint glass whose surface is etched into a slit shape. Can also. Examples of the type of the alignment film provided on the alignment substrate include polyimide, polyamide, and polyvinyl alcohol.
Further, the alignment film may be a deposition film obtained by obliquely depositing silicon oxide on an alignment substrate.

Next, a method of disposing a liquid crystalline substance on an alignment substrate as described above will be described. As the method, solution coating performed by preparing a solution of a liquid crystalline substance is preferable. Here, as a solvent capable of dissolving the liquid crystal substance,
In the case of the type or composition of the substance, it cannot be said unconditionally because it differs depending on the composition ratio, etc., for example, benzene,
Hydrocarbon solvents such as toluene, xylene, n-butylbenzene, diethylbenzene and tetralin; ether solvents such as methoxybenzene, 1,2-dimethoxybenzene and diethylene glycol dimethyl ether; acetone;
Ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl acetate, ethylene glycol monomethyl ether acetate, propylene ethylene glycol monomethyl ether acetate, γ-
Ester solvents such as butyrolactone, 2-pyrrolidone,
N-methyl-2-pyrrolidone, dimethylformamide,
Examples thereof include amide solvents such as dimethylacetamide, halogen solvents such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene and orthodichlorobenzene, and mixed solvents obtained by mixing two or more of the above solvents. You. The concentration of the solution cannot be determined unconditionally because it depends on the solubility of the liquid crystalline substance and the film thickness of the optical film finally intended, but usually 1 to 60% by weight,
Preferably it is in the range of 3 to 40% by weight.

Further, a surfactant may be added to the above solution. Examples of the surfactant include cationic surfactants such as imidazoline, quaternary ammonium salts, alkylamine oxides, and polyamine derivatives, polyoxyethylene-polyoxypropylene condensates, primary and secondary alcohol ethoxylates. , Alkylphenol ethoxylate, polyethylene glycol and its esters, sodium lauryl sulfate, ammonium lauryl sulfate, lauryl sulfate amines, alkyl-substituted aromatic sulfonates, alkyl phosphates, aliphatic or aromatic sulfonic acid formalin condensates, etc. Surfactants, amphoteric surfactants such as lauryl amide propyl betaine and lauryl amino acetate betaine, and nonionic surfactants such as polyethylene glycol fatty acid esters and polyoxyethylene alkylamine , Perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl / hydrophilic group-containing oligomer, perfluoroalkyl / lipophilic group-containing oligomer Fluorinated surfactants such as urethane containing a fluoroalkyl group can be used. The amount of the surfactant to be added depends on the type of the surfactant, the liquid crystal substance, the solution, or the alignment substrate to be applied, but is usually 10 ppm to the liquid crystal composition.
The range is 10%, preferably 100 ppm to 5%, and more preferably 0.1% to 1%.

As a solution coating method, a spin coating method,
Roll coating, printing, dipping and pulling, curtain coating, die coating, and the like can be employed. After the application, the solvent is removed by drying, and a liquid crystal material layer having a uniform thickness is formed on the support film or the alignment film. The conditions for drying and removing the solvent are not particularly limited, as long as the solvent can be substantially removed and the liquid crystal material layer does not flow or even falls off. Usually, the solvent is removed by air drying at room temperature, drying on an otto plate, drying in a drying oven, or blowing hot or hot air.

The thickness of the liquid crystalline material layer after the solvent has been removed by drying cannot be determined unconditionally depending on the kind of the liquid crystalline material and the use of the optical film. When used as an optical compensation film such as a retardation plate, it is usually 0.01 μm to 1 μm.
It is desirably in the range of 00 μm, preferably 0.1 μm to 20 μm, more preferably 0.2 μm to 10 μm.

The purpose of the coating / drying step is to first form a liquid crystal material layer uniformly on the supporting substrate. However, depending on the type of the liquid crystal material, the liquid crystal material may be formed at the temperature at which the solvent is removed. Or, the alignment may be completed lyotropically in the process of removing the solvent. However, it is usually desirable in the present invention to perform the following heat treatment step in order to align the liquid crystal or to obtain a more uniform alignment state.

The heat treatment is performed at a temperature higher than the liquid crystal transition point of the liquid crystalline substance. That is, the alignment is performed in the liquid crystal state of the liquid crystalline substance, or the liquid crystal phase is once brought into an isotropic liquid state higher than the temperature range in which the liquid crystal phase is exhibited, and then the temperature is lowered to the temperature range in which the liquid crystal phase is exhibited. . A method of changing the temperature within a temperature range exhibiting a liquid crystal phase can also be adopted. For example, a heat treatment is performed at a high temperature within the temperature range where the same nematic phase is exhibited, and after the liquid crystal is substantially aligned, the order of the liquid crystal alignment is increased by lowering the temperature, or a heat treatment is performed at a temperature that exhibits the nematic phase. After the formation, a method of lowering the temperature and aligning in a higher-order liquid crystal phase such as a smectic phase can also be used in the present invention.

The heat treatment temperature cannot be specified unconditionally because it varies depending on the type of liquid crystal substance, the composition ratio when using the composition, and the type of liquid crystal substance constituting the composition. ° C, preferably 50 ° C to 240 ° C
C, more preferably in the range of 60C to 230C. Also, the time required for the liquid crystal to be sufficiently aligned is:
Since it depends on the type of liquid crystal substance and the type of liquid crystal substance constituting the composition, it cannot be said unconditionally, but usually 5 seconds to 2 hours, preferably 10 seconds to 40 hours.
Minutes, more preferably in the range of 20 seconds to 20 minutes. 5
If the time is shorter than seconds, the temperature of the liquid crystalline material layer may not rise to a predetermined temperature, and the alignment may be insufficient. If the time is longer than 2 hours, productivity is undesirably reduced.

The method of fixing the alignment mode depends on the type of the liquid crystal substance used, but is roughly classified into the following two methods. One is, for example, in the case of using a polymer liquid crystal that can form a glass state below the liquid crystal transition point, after forming the liquid crystal in a desired orientation in the liquid crystal state, cooling to a temperature below the liquid crystal transition point of the liquid crystal. This can fix the orientation mode. As another method, when using a low-molecular liquid crystal having light or thermal crosslinking properties as a liquid crystalline substance, for example, aligning the liquid crystal, and then performing a light or thermal crosslinking reaction to form an alignment form formed in a liquid crystal state. Can be fixed. Examples of the liquid crystal substance having photo- or thermal cross-linking properties include (1) a liquid crystal compound having a cross-linkable functional group in the molecule alone or a composition comprising two or more types. (2) a cross-linkable functional group in the molecule. Composition comprising liquid crystalline compound having and liquid crystalline compound having no crosslinkable functional group (3) Consisting of non-liquid crystalline compound having a crosslinkable functional group in the molecule and liquid crystalline compound having no crosslinkable functional group And the like. Here, examples of the crosslinkable functional group include an acryl group, a methacryl group, a vinyl group, an allyl group, and a phthalimide group.

As described above, the liquid crystal material layer is formed on the alignment substrate and the alignment is fixed. The alignment mode varies depending on the type and composition ratio of the liquid crystalline substance used or the composition containing the substance, for example, homeotropic alignment, homogeneous alignment, twisted nematic alignment,
Cholesteric alignment or hybrid alignment is exemplified. For these alignment modes, it is necessary to adjust the type of the liquid crystalline substance, the composition ratio of the composition, and the like according to the use of the optical film. The optical film on the alignment substrate in which the alignment mode is fixed as described above is formed on the alignment substrate, and is provided on a supporting substrate different from the alignment substrate (hereinafter, referred to as a second substrate) with an adhesive / adhesive. In a state in which the film is transferred via the above-described method, or in a state of the film alone from which the alignment substrate is peeled off, the film is subjected to a laminating step described later. In addition, a protective layer such as a hard coat layer or a transparent plastic film sheet or a glass plate may be provided on the surface of the optical film for the purpose of protecting the surface.
Further, the optical film may be laminated on another optical member, for example, a polarizing plate, a retardation plate or the like.

Next, a method of laminating the transparent plate and the optical film will be described. In addition, the transparent plate-like body here refers to a plate-like body that is optically transparent, for example, a glass plate,
Acrylic resin, polycarbonate resin and the like can be mentioned. The method of laminating the transparent plate and the optical film via the polyvinyl acetal resin includes: (1) a method of applying a polyvinyl acetal resin on the transparent plate in advance, followed by thermocompression bonding with the optical film; A method in which a polyvinyl acetal resin is applied on an optical film in advance and then thermocompression-bonded to a transparent plate. (3) The polyvinyl acetal resin applied on a separator such as a film whose surface has been release-treated is coated on the transparent plate. After transferring, a method of peeling the separator and thermocompression bonding with the optical film. (4) Transferring the polyvinyl acetal resin applied on the separator to the optical film in the same manner as in (3), peeling the separator, and removing the transparent plate. And a method of thermocompression-bonding with a state body. From the viewpoint of good workability, (2) or (4) is preferable.

[0029]

The optical film laminate adhered to the transparent plate by the polyvinyl acetal resin of the present invention can reduce peeling and distortion at the peripheral portion of the film, which is a problem when an adhesive is used, and is excellent in workability. Since it has optical transparency, it is suitable for application to optical elements. When the optical film is a liquid crystal alignment film, a color compensator for a liquid crystal display device, a viewing angle improving plate for a liquid crystal display device, an optical retardation plate, a １ ／ wavelength plate, a 波長 wavelength plate depending on the alignment state of the liquid crystal used. , Optical rotatory optical element polarizing film, diffraction grating film,
It can be widely applied to applications such as cholesteric polarizing plates, light diffusion films, and light condensing films, and its industrial utility value is extremely large.

[0030]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples. (Example 1)

[0031]

Embedded image

15 wt% containing the optically active polymer liquid crystal represented by the above formulas -a and b in a weight ratio of 96: 4.
% Phenol / tetrachloroethane (60/40 weight ratio) mixed solvent solution was prepared and applied by spin coating on a rubbed polyimide film. 70 ° C
Was dried on a hot plate for 1 hour, heat-treated in a clean oven at 210 ° C. for 30 minutes, allowed to cool naturally, and the alignment was fixed to glass to obtain a liquid crystal alignment film. The obtained film was transferred from a polyimide film to a triacetyl cellulose (TAC) film using a UV curable adhesive to obtain an optical film. Corona discharge treatment was performed on the TAC surface of this optical film, and the surface tension of the treated surface was 55 mN / m. Next, after applying Sekisui Chemical Co., Ltd. polyvinyl acetal resin solution Esrec KX-5 (8 wt% solution of a mixed solvent of water / isopropyl alcohol) on the TAC surface with a bar coater,
It was dried in a clean oven at 100 ° C. for 10 minutes.
The thickness of the polyvinyl acetal layer was 20 μm. Then, after superimposing on a glass plate, 120 ° C, 8 kgf /
In cm ² and pressed for 20 minutes heat, to give a laminate consisting of optical film / poly (vinyl acetal) / glass plate. When the obtained laminate was left at room temperature and observed one month later, no abnormal appearance such as peeling or distortion was observed.

(Embodiment 2)

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A 20 wt% solution was prepared by dissolving a crosslinkable liquid crystal composition (weight ratio 70:20:10) comprising the above formulas -a, b and c in m-xylene. A photoreaction initiator (Irgacure 369, Ciba-Geigy) was added to the composition at 2 wt% to prepare a photocurable liquid crystal composition solution. This solution was applied on a rubbed triacetyl cellulose film (TAC) by dip coating, dried in a 50 ° C. clean oven for 5 minutes, and then heat-treated in a 80 ° C. clean oven under a nitrogen atmosphere for 15 minutes. went. After the heat treatment, light curing was performed by irradiating light of 1200 mJ / cm ² at a cumulative amount of light of 365 nm by a high-pressure mercury lamp installed in an oven to obtain an optical film. Corona discharge treatment was performed on the TAC surface of this optical film, and the surface tension of the treated surface was 53 mN / m. Next, after applying Sekisui Chemical Co., Ltd. polyvinyl acetal resin solution Esrec KX-5 (8 wt% solution of a mixed solvent of water / isopropyl alcohol) on the TAC surface with a bar coater, the coating was dried in a clean oven at 100 ° C. for 10 minutes. I let it. The thickness of the polyvinyl acetal layer was 22 μm. Then, after overlapping with the glass plate,
Thermocompression bonding was performed at 120 ° C. and 8 kgf / cm ² for 20 minutes to obtain a laminate composed of an optical film / polyvinyl acetal / glass plate. When the obtained laminate was left at room temperature and observed one month later, no abnormal appearance such as peeling or distortion was observed.

(Embodiment 3)

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The weight ratio of the liquid crystalline polymer represented by the formula -a and the optically active liquid crystalline polymer represented by b is 99: 1.
A phenol / tetrachloroethane (60/40 weight ratio) mixed solvent solution containing 15% by weight of phenol / tetrachloroethane was prepared and applied by spin coating to a rubbed polyethersulfone film. After drying on a hot plate at 70 ° C. for 1 hour, the solution was dried in a clean oven at 220 ° C. for 2 hours.
Heat treated for 0 minutes. Thereafter, the orientation was fixed to glass by natural cooling to obtain a liquid crystal alignment film. After transferring the obtained liquid crystal alignment film from a polyether sulfone film to a polyethylene terephthalate film (PET) using a UV-curable adhesive, a UV-curable hard coat agent is applied to the liquid crystal alignment film and UV irradiation is performed. And cured. Thus, an optical film consisting of the hard coat layer / liquid crystal alignment film layer / UV adhesive layer / PET was obtained. The hard coat surface of this optical film was subjected to corona discharge treatment, and the surface tension of the treated surface was set to 52 mN / m. Next, after applying Sekisui Chemical Co., Ltd. polyvinyl acetal resin solution Esrec KX-5 (8 wt% solution of a mixed solvent of water and isopropyl alcohol) on the hard coat surface with a bar coater, the coating was performed in a clean oven at 100 ° C. for 10 minutes. Let dry. The thickness of the polyvinyl acetal layer was 20 μm. Subsequently, after overlapping with the glass plate, the PET film was peeled off from the optical film. Subsequently, thermocompression bonding is performed at 120 ° C. and 8 kgf / cm ² for 20 minutes.
A laminate composed of a liquid crystal alignment film / polyvinyl acetal / glass plate was obtained. When the obtained laminate was left at room temperature and observed one month later, no abnormal appearance such as peeling or distortion was observed.

Example 4 An ultraviolet absorber (Cyasorb manufactured by Cytec, USA) was added to a polyvinyl acetal resin solution.
UV-24) was added in the same manner as in Example 3 except that 10 parts by weight of the resin solid content was added to obtain a laminate composed of a liquid crystal alignment film / polyvinyl acetal (containing an ultraviolet absorber) / glass plate. When the obtained laminate was left at room temperature and observed one month later, no abnormal appearance such as peeling or distortion was observed.

(Comparative Example 1) A laminate composed of a liquid crystal alignment film / acrylic adhesive / glass plate was obtained in the same manner as in Example 1 except that an acrylic adhesive was used instead of polyvinyl acetal. The resulting laminate was left at room temperature for 1 hour.
When the observation was performed after one month, peeling and distortion occurred at the periphery of the film.

(Comparative Examples 2 and 3) A laminate composed of a liquid crystal alignment film / acrylic adhesive / glass plate was prepared in the same manner as in Examples 2 and 3, except that an acrylic adhesive was used instead of polyvinyl acetal. I got When the obtained laminate was left at room temperature and observed one month later, peeling and distortion occurred at the periphery of the film.

[0040]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a sectional view of an example of an optical film laminate.

FIG. 2 is a cross-sectional view of another example of an optical film laminate.

[Explanation of symbols]

 1, 3: cured acrylic resin layer 2: liquid crystal alignment film layer with fixed orientation 4: transparent plastic film 5: polyvinyl acetal layer 6: transparent plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H049 BA02 BA06 BA26 BB13 BB51 BC02 BC09 4F100 AG00 AJ06 AK23C AK23G AK49 AS00A AT00B BA02 BA03 BA07 BA26 CA05C CA07C CB03C EJ05A EJ55A GB51 GB61 GB90 J20AJBBJJB13

Claims (5)

[Claims] 1. An optical film laminate obtained by laminating an optical film and a transparent plate-like body, wherein the optical film and the transparent plate-like body are bonded by a hot melt type adhesive made of polyvinyl acetal resin. Optical film laminate. 2. An optical film, comprising: a liquid crystal alignment film formed from a liquid crystal material, wherein the liquid crystal material has a liquid crystal alignment film formed in a liquid crystal state, wherein the liquid crystal material is cooled to a liquid crystal transition temperature or lower to fix the liquid crystal alignment film. The optical film laminate according to claim 1, wherein the laminate is a laminated film having at least one film. 3. The liquid crystal alignment film, wherein the optical film is formed from a liquid crystal material having photo- or thermal cross-linking properties, and the liquid crystal material is fixed in a liquid crystal state by an optical or thermal cross-linking reaction. The optical film laminate according to claim 1, wherein the laminate is a laminated film having at least one film. 4. The optical film laminate according to claim 1, wherein the hot melt adhesive comprising a polyvinyl acetal resin contains an ultraviolet absorber and / or a light stabilizer. . 5. The optical film laminate according to claim 1, wherein a corona discharge treatment is applied to a surface of the optical film in contact with the polyvinyl acetal resin.