CN1734321A - Method for manufacturing liquid crystal alignment film, liquid crystal alignment film, optical film and image viewing display - Google Patents

Abstract

The present invention provides a method for manufacturing a liquid crystal alignment film, which is characterized in that it includes: the step (1) of performing alignment treatment on a transparent substrate film by rubbing, and attaching a surface protection sheet with a peeling force of 0.5N/50mm or less to the The step (2) of the alignment treatment surface, the step (3) of coating a liquid crystal material containing a liquid crystal monomer and/or a liquid crystal polymer on the alignment treatment surface after peeling off the surface protection sheet, and making the liquid crystal The step (4) of immobilization is performed after the material is oriented. Therefore, this invention provides the manufacturing method of the liquid crystal aligning film which can orientate a liquid crystal material favorably on the base film which orientation-processed by rubbing.

Description

Liquid crystal alignment film and its manufacturing method, optical film and image display device

technical field

The invention relates to a method for manufacturing a liquid crystal alignment film. Moreover, this invention relates to the optical film using the liquid crystal aligning film obtained by this manufacturing method, and this liquid crystal aligning film at least one sheet. The liquid crystal alignment film of the present invention can be used alone or in combination with other films as optical films such as retardation plates, viewing angle compensation films, optical compensation films, and elliptically polarizing films. Furthermore, the present invention also relates to image display devices such as liquid crystal display devices, electroluminescent display devices, and PDPs using the above-mentioned optical film.

Background technique

In recent years, retardation plates that control the phase of light have become one of the important optical elements in the fields of optics and optoelectronics. In addition, an elliptically polarizing plate can be obtained by bonding a retardation plate to a polarizing plate, and various configurations have been studied based on the retardation value and wavelength dispersion of the retardation plate.

In the past, retardation plates were produced by uniaxially or biaxially stretching polymer films. As a material of the polymer film, for example, polycarbonate resin is used, and its wavelength dispersion is large, and the retardation becomes higher toward the shorter wavelength side. In contrast, currently used retardation plates use norbornene-based resins with small wavelength dispersion or modified polycarbonate resins with higher retardation toward the longer wavelength side. In addition, these retardation plates are being used by stacking them at various angles. However, norbornene-based resins and modified polycarbonates are more expensive than polycarbonate resins. Their stacking increases the cost even further. In addition, these laminates need to be punched at various axial angles and laminated with veneers, so process costs and time are required, and they also cause quality degradation.

On the other hand, a liquid crystal alignment layer formed on an alignment base material is known as a phase difference plate. This liquid crystal alignment layer is obtained by coating a liquid crystal material such as a liquid crystal monomer or a liquid crystal polymer on an alignment substrate, aligning the liquid crystal material, and then curing it (see Patent Document 1). Liquid crystal materials include rod-like nematic liquid crystals, discotic liquid crystals, and the like, and there are various types depending on wavelength dispersion characteristics, like retardation plates using stretched films. Examples of the orientation substrate include stretched polymer films and rubbed orientation films.

When orienting a liquid crystal material on a stretched polymer film, axial precision of the stretched polymer film is required. However, the stretched polymer film produced by the conventional longitudinal stretching and transverse stretching methods cannot stably and inexpensively obtain an axis accuracy of ±1° or more in the width direction. Therefore, the stretched polymer film is sometimes used as a C plate that does not require axial precision (when the refractive index of the plane is nx, ny, and the refractive index of the thickness direction is nz, nxny>nz or nz>nxny ) or cholesteric liquid crystal alignment substrates, but it is difficult to be used in the production of A-plates (nx>nynz or nx<nynz) that require axis precision. In addition, if the surface of the rubbed alignment film is contaminated before coating the liquid crystal material, the orientation of the liquid crystal material will be reduced, making it difficult to obtain a liquid crystal alignment layer with good orientation. For example, when the surface of the rubbed alignment film is brought into contact with a roller or the like before the process of applying the liquid crystal material after rubbing the base film, the orientation of the liquid crystal material decreases. Therefore, in the manufacturing method of the liquid crystal alignment film which used the rubbed alignment film, it is difficult to adopt the continuous production method by roll-to-roll (roll to roll).

Patent Document 1: Patent No. 2784680 specification

Contents of the invention

The object of this invention is to provide the manufacturing method of the liquid crystal aligning film which can orientate a liquid crystal material favorably on the base film which orientation-processed by rubbing.

Moreover, the object of this invention is to provide the liquid crystal aligning film obtained by this manufacturing method, the optical film using this liquid crystal aligning film, and the image display apparatus using this optical film.

As a result of earnest research by the present inventors to achieve the above object, it was found that the above-mentioned subject can be solved by the manufacturing method of the liquid crystal aligning film shown below, and completed this invention.

That is, the present invention relates to a method for producing a liquid crystal alignment film, which is characterized in that it includes: a step (1) of performing an alignment treatment on a transparent base film by rubbing, and attaching a surface protection sheet having a peeling force of 0.5 N/50 mm or less. The step (2) applicable to the alignment treatment surface, the step (3) of applying a liquid crystal material containing a liquid crystal monomer and/or a liquid crystal polymer on the alignment treatment surface after peeling off the surface protection sheet, using The step (4) of fixing the liquid crystal material after alignment.

In the above-mentioned method for producing a liquid crystal alignment film of the present invention, between the rubbing alignment treatment step (1) and the liquid crystal material coating step (3), there is a step of attaching a surface protection sheet to the rubbed alignment treatment surface. In the bonding step (2), the rubbed alignment-treated surface will not come into contact with other objects immediately before the liquid crystal material is coated. Therefore, the alignment-treated surface can suppress a decrease in alignment due to contamination, maintain good alignment, and in this case, can align a liquid crystal material. Therefore, the liquid crystal aligning film which has an arbitrary slow axis with respect to the long-axis direction of a film can be continuously produced roll-to-roll, without reducing the orientation of a liquid crystal material. Thereby, the liquid crystal aligning film which can correspond to even a large size and can be utilized for a phase difference plate etc. can be manufactured cheaply. The manufacturing method of the liquid crystal aligning film of this invention can be used for the manufacturing method of various retardation plates, but it is especially preferably used for the manufacturing method of retardation plates, such as A plate which requires axial precision.

As the surface protection sheet used in the step (2), one having a peeling force of 0.5 N/50 mm or less can be used. The peeling force represents the force (N/50mm) when the surface protection sheet is peeled off at a speed of 300 mm/min by 180° peeling with respect to the triacetyl cellulose film. Specifically, it is measured by the method described in the Example. When the peeling force of the surface protection sheet exceeds 0.5 N/50 mm, the peeling of the surface protection sheet disturbs the orientation of the rubbing-treated surface and reduces the orientation of the liquid crystal material. The peel force is preferably 0.5 N/50 mm or less, more preferably 0.3 N/50 mm or less. Among them, the peel force is preferably 0.03 N/50 mm or more, more preferably 0.05 N/50 mm or more, from the viewpoint of the function of protecting the orientation-treated surface with the surface protection sheet.

In the manufacturing method of the liquid crystal alignment film, as the surface protection sheet, it is preferable to use a surface protection sheet that has a base material layer and an adhesive layer and is produced by co-extruding them or by coating an adhesive layer on the base material layer. Protective sheet. As the surface protection sheet, it is preferable to use a protective sheet in which the substrate layer contains an olefin-based resin and the adhesive layer contains an ethylene-vinyl acetate copolymer.

In the manufacturing method of the said liquid crystal aligning film, when performing peeling of the surface protection sheet in process (3), it is preferable that the transparent base film is uniformly charged either positively or negatively. When peeling off the surface protection sheet, as long as the transparent base film is uniformly charged with either type of charge, it is considered that the rubbed alignment-treated surface can maintain orientation. Confirmation of uniform charge can be carried out by scattering positively and negatively charged colored metal powders (for example, toners having different colors by charging).

Moreover, this invention relates to the liquid crystal aligning film obtained by the manufacturing method of the said liquid crystal aligning film.

Moreover, this invention also relates to the optical film characterized by using at least one sheet of said liquid crystal alignment film. The liquid crystal alignment film is thin and has a uniform phase difference, and is suitable for use as a phase difference plate. Moreover, a liquid crystal aligning film (retardation plate) can be used suitably as an elliptically polarizing plate etc. in combination with a polarizing plate.

In addition, the present invention also relates to an image display device using the optical film.

Furthermore, the present invention relates to a surface protection sheet having a peeling force of 0.5 N/50 mm or less, which is used in the step (2) in the method for producing the liquid crystal optical film.

Description of drawings

FIG. 1 is a photograph showing the color distribution of the attached toner showing a charged state in Example 1. FIG.

2 is a photograph showing the color distribution of attached toner showing a charged state in Example 2. FIG.

Detailed ways

Next, each process is demonstrated sequentially about the manufacturing method of the liquid crystal aligning film of this invention.

(Process (1))

In the step (1), the transparent substrate is subjected to an orientation treatment by rubbing.

<Transparent base film>

The transparent base film is not particularly limited as long as it is a material that does not change at the temperature at which the liquid crystal material is oriented. For example, various plastic films, glass plates, metals, etc. can be used in a single layer or laminated. Examples of plastic films include polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose, and polyethylene terephthalate. Films made of transparent polymers such as carbonate-based polymers and acrylic polymers such as polymethyl methacrylate. In addition, styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers, polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and olefins such as ethylene-propylene copolymers can also be mentioned. Films made of transparent polymers such as polyvinyl chloride-based polymers, amide-based polymers such as nylon and aramid. Furthermore, examples of imide-based polymers, sulfone-based polymers, polyethersulfone-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, Films made of transparent polymers such as vinyl polymers, polyvinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, or mixtures of the above polymers, etc. As the transparent base film, a triacetyl cellulose film, a norbornene resin film, or an olefin-based film is preferable.

In addition, as the transparent base film, a polyvinyl alcohol-based film, a polyimide-based film, a polysiloxane-based film, or a vitreous polymer film can be used.

As a material for forming a glassy polymer thin film, metal alkoxides (alcoxides), particularly metal alkoxide silica sols, tend to be used. Metal alkoxides are generally used as alcohol-based solutions. After the solution is applied on the substrate film, the solvent is removed, and the sol-gel reaction is promoted by heating, whereby a transparent glassy polymer film is formed on the substrate film. The metal alkoxide silica gel layer is formed from the metal alkoxide silica sol. As a method of coating the above metal alkoxide silica sol solution on the substrate, for example, a roll coating method, a gravure coating method, a bar coating method and the like can be employed. As a method for removing the solvent and accelerating the reaction, drying at room temperature, drying in a drying oven, and the like are generally available.

As the rubbing treatment, the orientation treatment may be performed by rubbing the upper surface of the base film (rubbing) with a cloth made of fine fibers such as rayon or cotton yarn, or a leather material. The cloth or leather material may be rubbed in one direction by rubbing them with a rubbing roll curled. In addition, the rubbing roller can change the shaft angle in the direction of 0° to ±45°. Retardation plates (compensation plates) having various optical axes can be produced using a liquid crystal alignment film obtained by changing the axis angle and rubbing the material in this way.

(Process (2))

In the step (2), a surface protection sheet having a peeling force of 0.5 N/50 mm or less is bonded to the orientation-treated surface.

The surface protection sheet is not particularly limited as long as the peeling force is 0.5 N/50 mm or less, and may be formed of one layer or may be formed of two or more layers. In the surface protection sheet formed of one layer, the one layer satisfies a peeling force of 0.5 N/50 mm or less. On the other hand, in the surface protection sheet formed of two or more layers, at least one layer is used as a base material layer, and at least one layer is used as an adhesive layer. The adhesive layer side is bonded to the orientation-treated surface.

Next, the surface protection sheet which has a base material layer and an adhesive layer is demonstrated. The production method for forming the surface protection sheet having the base material layer and the adhesive layer is not particularly limited, but it is preferable to form the base material layer and the adhesive layer into a film by a co-extrusion method. As the co-extrusion method, it can be carried out according to the expansion method, the T-die method, etc. which are generally used in film production and the like. In addition, a production method in which a surface protection sheet is formed by coating on a substrate layer to form an adhesive layer and transferring it may also be employed.

Examples of the material forming the base material layer include olefin-based resins. Olefin-based resins are olefin homopolymers or copolymer resins such as block polymers and random polymers using various olefins and other monomers, specifically exemplified by propylene-based polymers, low-density polyethylene, high-density polyethylene, etc. Ethylene-based polymers such as ethylene, medium-density polyethylene, and linear low-density, ethylene-propylene copolymers, ethylene-α-olefin copolymers, olefin-based polymers such as TPO, and olefins such as ethylene-methyl methacrylate copolymers Olefinic copolymers with other monomers.

In order to prevent deterioration and the like, a light stabilizer such as an antioxidant, an ultraviolet absorber, and a hindered amine light stabilizer may be added to the supporting base material. In addition, antistatic agents can also be used, as well as fillers such as calcium oxide, magnesium oxide, silicon oxide, zinc oxide, and titanium oxide, pigments, anti-eye excrement agents, lubricants, anti-blocking agents and other suitable additives.

The thickness of the substrate layer is 20 to 300 μm, particularly 30 to 250 μm, preferably 40 to 200 μm, but not limited thereto.

As the resin forming the adhesive layer, ethylene-ethyl acetate copolymer is preferable. In addition, as a material constituting the adhesive layer, known adhesives such as rubber-based, acrylic-based, or urethane-based adhesives can be used, for example. Examples of rubber-based polymers include diene-based polymers such as natural rubber, polyisobutylene, butyl rubber, polyisoprene, and polybutadiene, or their hydrogenated products, ethylene-propylene rubber, ethylene - Olefin-based rubbers such as α-olefin, ethylene-propylene-α-olefin or propylene-α-olefin, styrene-butadiene-styrene (SBS) or styrene-isoprene-styrene (SIS), A-B-A block polymers such as styrene-ethylene-isoprene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), or styrene-butadiene (SB) or benzene A-B block copolymers such as ethylene-isoprene (SI), styrene-ethylene-butylene copolymer (SEB), styrene-ethylene-propylene copolymer (SEP), styrene-butadiene Styrenic random copolymers such as rubber (SBR) or hydrogenated styrenic random copolymers (HSBR), A-B-O type styrene- Rubber-based polymers such as olefin crystal-based block copolymers, C-B-C type olefin crystal-based block copolymers such as olefin crystal-ethylene-butene copolymer-olefin crystal (CEBC), etc., which are base polymers.

When forming the adhesive layer, for the purpose of controlling the adhesive properties, etc., softeners, olefin resins, silicone polymers, liquid acrylic copolymers, phosphate ester compounds, tackifiers, etc. can be added as needed. Aging agent, hindered amine light stabilizer, ultraviolet absorber, and suitable additives such as calcium oxide, magnesium oxide, silicon dioxide, zinc oxide, titanium oxide and other fillers or pigments.

The thickness of the adhesive layer can be appropriately determined depending on the peeling force, etc., and is generally 1 to 50 μm, preferably 2 to 40 μm, particularly preferably 5 to 20 μm. If necessary, a spacer or the like may be temporarily attached for protection until the adhesive layer is used.

The surface protection sheet is bonded to the alignment-treated surface. However, in order not to contaminate the orientation-treated surface, it is preferable to bond immediately after the step (1) is completed.

(Process (3))

In the step (3), after the surface protection sheet is peeled off, a liquid crystal material containing a liquid crystal monomer and/or a liquid crystal polymer is applied to the alignment-treated surface.

In order not to contaminate the alignment treatment surface, the peeling of the surface protection sheet is preferably performed immediately before the application of the liquid crystal material. The peeling method of the surface protection sheet is not particularly limited, and it is preferable to peel at a certain speed so as not to damage the orientation of the orientation-treated surface. For example, it is preferably performed with a 180° peel. In the present invention, since a surface protection sheet having a peeling force of 0.5 N/50 mm or less is used, the orientation-treated surface of the transparent base film after peeling off the surface protection sheet may also be charged with either positive or negative charges.

The liquid crystal material contains a liquid crystal monomer or a liquid crystal polymer, or a mixture thereof.

Liquid crystal monomers have various skeletons showing nematic, cholesteric, or smectic liquid crystal alignment, and have at least one unsaturated double bond such as acryloyl, methacryloyl, vinyl, or epoxy at the end Liquid crystal compounds with polymerizable functional groups. Among these liquid crystal monomers, nematic liquid crystal compounds having at least one unsaturated double bond such as an acryloyl group or a methacryloyl group tend to be used. As a liquid crystal monomer, in order to improve durability, the monomer which has 2 or more photopolymerizable functional groups is preferable. Specific examples of such liquid crystal monomers include monomers represented by the following formula (1). These liquid crystal monomers may be used alone or in combination of two or more.

[chemical 1]

In the above formula (1), A ¹ and A ² each represent a polymerizable group, and may be the same or different. In addition, either one of ^A1 and ^A2 may be hydrogen. X represents single bond, -O-, -S-, -C=N-, -O-CO-, -CO-O-, -O-CO-O-, -CO-NR-, -NR-CO -, -NR-, -O-CO-NR-, -NR-CO-O-, -CH ₂ -O- or -NR-CO-NR, in the X, R represents H or C ₁ ~C ₄ alkyl, M represents a linear mesogene group.

In the above formula (1), X may be the same or different, but is preferably the same. Even in the monomer of the above formula (1), it is preferable that A ² is arranged at the para position with respect to A ¹ .

In addition, it is preferable that A ¹ and A ² are independently represented by the following formula ZX-(Sp) _n ... (2), and A ¹ and A ² are preferably the same group.

In the above formula (2), Z represents a crosslinkable group, X is the same as the above formula (1), Sp represents a spacer group composed of a linear or branched chain alkyl group having 1 to 30 C atoms, and n means 0 or 1. The carbon chains in the above Sp may also be filled by oxygen in ether functional groups, sulfur in thioether functional groups, non-adjacent imino groups or C ₁ -C ₄ alkylimino groups.

In the above formula (2), Z is preferably any one of atomic groups represented by the following formulas. In the following formulae, as R, groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl are exemplified.

[Chemical 2] H ₂ C=CH-, HC≡C-,

-N=C=O, -N=C=S, -O-C≡N,

In addition, in the above formula (2), Sp is preferably any one of the atomic groups represented by the following formulas, and in the following formulas, m is preferably 1-3, and p is 1-12.

[Chem 3]

-(CH ₂ ) _p -, -(CH ₂ CH ₂ O) _n CH ₂ CH ₂ -, -CH ₂ CH ₂ SCH ₂ CH ₂ -,

_{-CH2CH2NHCH2CH2- , _ _}

In the above formula (1), M is preferably represented by the following formula (3), and in the following formula (3), X is the same as X in the above formula (1). Q represents, for example, a substituted or unsubstituted alkylene group or an aromatic hydrocarbon atom group, and may also be, for example, a substituted or unsubstituted linear or branched C ₁ -C ₁₂ alkylene group.

[chemical 4]

When the aforementioned Q is the aforementioned aromatic hydrocarbon atomic group, for example, an atomic group represented by the following formula or a substituted analog thereof is preferable.

[chemical 5]

As a substituted analogue of the aromatic hydrocarbon atomic group represented in the above formula, for example, there may be 1 to 4 substituents on each aromatic ring, and it is also possible to have 1 or 2 substituents on each aromatic ring or group. 2 substituents. The above-mentioned substituents may be respectively the same or different. Examples of the substituent include a C ₁ -C ₄ alkyl group, a nitro group, a halogen such as F, Cl, Br, and I, a phenyl group, a C ₁ -C ₄ alkoxy group, and the like.

Specific examples of the liquid crystal polymer include monomers represented by the following formulas (4) to (19).

[chemical 6]

The temperature range in which the above-mentioned liquid crystal monomer exhibits liquid crystallinity varies depending on its type, and is, for example, preferably in the range of 40 to 120°C, more preferably in the range of 50 to 100°C, and particularly preferably in the range of 60 to 90°C.

A polymerization initiator is usually contained in a liquid crystal material containing a liquid crystal monomer. A polymerization initiator corresponding to the polymerization method of the liquid crystal monomer can be appropriately selected. As a polymerization method of the polymerizable liquid crystal monomer, for example, ultraviolet polymerization is mentioned, and a photopolymerization initiator is used in this case. Various photopolymerization initiators can be used without particular limitation. As a photopolymerization initiator, Irgacure 907, Irgacure 184, Irgacure 651, Irgacure 369, etc. manufactured by Tsunomis Beshiyari Tei Chemicals Co., Ltd. can be illustrated, for example. In consideration of the kind of liquid crystal monomer, the photopolymerization initiator may be added in such an amount that the orientation is not disturbed. Usually, it is preferably about 0.5 to 30 parts by weight relative to 100 parts by weight of the liquid crystal monomer. More preferably, it is 2-7 weight part, More preferably, it is 3-6 weight part.

As the liquid crystal polymer, there can be used polymers with various skeletons of the main chain type, side chain type, or complex types thereof showing nematic, cholesteric, or smectic liquid crystal alignment without particular limitation.

Examples of main-chain liquid crystal polymers include condensation-based polymers having a structure in which linear mesogene groups composed of aromatic units and the like are bonded, such as polyether-based, polyamide-based, and polycarbonate-based polymers. , polyesterimide and other polymers. Examples of the above-mentioned aromatic unit to be a linear mesogene group include phenyl, biphenyl, and naphthyl, and these aromatic units may have a cyano group, an alkyl group, an alkoxy group, or a halogen group. and other substituents.

Examples of side chain-type liquid crystal polymers include polyacrylates, polymethacrylates, polysiloxanes, and polymalonic acid-based main chains with cyclic units on the side chains. A straight-line atomic group (mesogene)-based polymer. Examples of the above-mentioned cyclic unit to be a linear mesogene group include biphenyl, phenylbenzoate, phenylcyclohexane, azobenzene, methylimine, diphenyl Azobenzene series, phenyl pyrimidine series, tolantene series, diphenyl benzoate series, bicyclohexane series, cyclohexylbenzene series, terphenyl series, etc. However, the terminals of these cyclic units may have substituents such as cyano, alkyl, alkoxy and halogen, for example.

In addition, linear mesogene groups of any liquid crystal polymer may be bonded via a spacer portion that imparts flexibility. A polymethylene chain, a polyoxymethylene chain, etc. are mentioned as a spacer part. The repeating number of the structural unit forming the spacer is appropriately determined by the chemical structure of the linear atomic group (mesogene), but the repeating unit of the polymethylene chain is 0 to 20, preferably 2 to 12, and the polyoxyethylene chain is preferably 2 to 12. The repeating unit of the methyl chain is 0-10, preferably 1-3.

Among them, the nematic liquid crystal polymer can be converted into a cholesteric liquid crystal polymer by containing a low-molecular chiral agent or introducing a chiral component into the polymer component.

The molecular weight of the liquid crystal polymer is not particularly limited, but preferably has a weight average molecular weight of about 2,000 to 100,000. If the weight average molecular weight of the liquid crystal polymer is large, the weight average molecular weight of the liquid crystal polymer is more preferably 50,000 or less from the viewpoint of orientation as a liquid crystal. In addition, if the weight average molecular weight of the liquid crystal polymer becomes small, the film-forming property as a non-fluid layer tends to be poor, so the weight average molecular weight of the liquid crystal polymer is more preferably 2.5 thousand or more.

The liquid crystal material may contain a liquid crystal monomer or a liquid crystal polymer, or a mixture thereof. The method of applying the liquid crystal material to the alignment-treated surface includes a solution coating method using a solution of the liquid crystal material dissolved in a solvent or a method of melt coating after melting, among which the solution coating method is preferable.

As the solvent used when preparing the above-mentioned solution, it differs depending on the type of liquid crystal material or transparent substrate film, so it cannot be generalized, but chloroform, dichloromethane, dichloroethane, tetrachloroethane, trichloro Halogenated hydrocarbons such as ethylene, tetrachloroethylene, and chlorobenzene; phenols such as phenol and p-chlorophenol; aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, and 1,2-dimethoxybenzene; acetone , ethyl acetate, tert-butanol, glycerol, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diglyme, ethyl cellosolve, butyl cellosolve, 2-pyrrolidone, N -Methyl-2-pyrrolidone, pyridine, triethylamine, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethylsulfoxide, acetonitrile, butyronitrile, carbon disulfide, and the like. The concentration of the solution cannot be generalized because it depends on the solubility of the liquid crystal material used or the film thickness of the final liquid crystal thin film, but it is usually in the range of 3 to 50% by weight, preferably 7 to 30% by weight.

In addition, the liquid crystal material may contain additives as appropriate. Moreover, it can also become a cholesteric liquid crystal material by adding a chiral agent.

The thickness of the liquid crystal alignment layer obtained from the applied liquid crystal material is preferably about 1 to 10 μm. Among them, when it is particularly necessary to precisely control the film thickness of the liquid crystal layer, since the film thickness is roughly determined at the stage of coating on the transparent substrate film, it is necessary to pay special attention to controlling the concentration of the solution, the film thickness of the coating film, and the like.

As a coating method for applying the above-mentioned solution adjusted to a desired concentration using the above-mentioned solvent on the rubbed-treated orientation-treated surface, for example, roll coating, gravure coating, bar coating, etc. can be used. After coating, the solvent is removed to form a liquid crystal layer on the base film. The conditions for removing the solvent are not particularly limited, as long as the solvent can be substantially removed and the liquid crystal layer does not flow or flow down. The solvent is usually removed by drying at room temperature, drying in a drying oven, heating on a hot plate, or the like.

(Process (4))

In a process (4), after aligning the said liquid crystal material, a liquid crystal alignment layer is fixed. Thereby, the liquid crystal alignment layer was fixed and the liquid crystal alignment film was obtained.

Alignment of the liquid crystal material is performed by bringing liquid crystal monomers and/or liquid crystal polymers into a liquid crystal state. For example, heat treatment is performed to align the liquid crystal material in a liquid crystal state within the liquid crystal temperature range. As a heat treatment method, it can be performed by the method similar to the above-mentioned drying method. Although the heat treatment temperature cannot be generalized because it differs depending on the type of liquid crystal material and base film to be used, it is usually performed within the range of 60 to 300°C, preferably 70 to 200°C. In addition, the heat treatment time varies depending on the heat treatment temperature, the liquid crystal material used, and the type of base film, so it cannot be generalized, but it is usually selected between 10 seconds to 30 minutes, preferably 30 seconds to 15 minutes. When it is shorter than 10 seconds, there is a possibility that orientation formation cannot be sufficiently performed; when it is longer than 30 minutes, mass production efficiency may deteriorate.

As a method of fixing the aligned liquid crystal material, when the liquid crystal material contains a liquid crystal monomer, it is polymerized and solidified. Various means can be used for polymerization curing depending on the type of liquid crystal monomer, for example, a photopolymerizable method by light irradiation can be used. Polymerization curing by light irradiation is preferably employed. By polymerization curing, liquid crystal monomers are polymerized or cross-linked and then fixed to obtain a highly durable film. Light irradiation is performed by ultraviolet irradiation, for example. The ultraviolet irradiation conditions are preferably in an inert gas environment to promote the full progress of the reaction. Typically used is a high-pressure mercury ultraviolet lamp with an illuminance of about 80 to 300 mW/cm ² . Other types of lamps such as metal halide UV lamps or incandescent lamps can also be used. In addition, in order to make the surface temperature of the liquid crystal layer at the time of ultraviolet irradiation within the liquid crystal temperature range, the distance to the thin film can be adjusted by cold mirror, water cooling, other cooling treatments or speeding up the line speed.

When the liquid crystal material does not contain liquid crystal cells but only contains liquid crystal polymers, the liquid crystal alignment layer can be cooled to a temperature below the liquid crystal temperature by cooling to fix it.

The liquid crystal aligning film which consists of the said liquid crystal aligning layer can be used together with the said base film, and can also peel this from a base film and use it as an optical film. Furthermore, it can also be used by transcribe|transferring to another optical film. The above-mentioned liquid crystal alignment film can be used alone or in combination with other films to be used as optical films such as retardation plates, viewing angle compensation films, optical compensation films, and elliptically polarized light films. They are described below.

Polarizing plates are used in optical films used in image display devices such as liquid crystal display devices. Polarizers usually have a protective film on one or both sides of the polarizer. The polarizer is not particularly limited, and various polarizers can be used. As a polarizer, for example, on a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially methylated polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partially saponified film, iodine or dichroic Materials that are uniaxially stretched after dichroic substances such as neutral dyes; polyolefin-based oriented films such as dehydration-treated products of polyvinyl alcohol or dehydrochloric acid-treated products of polyvinyl chloride, etc. Among them, it is preferable to use a polarizer obtained by stretching a polyvinyl alcohol-based film, absorbing a dichroic material (iodine, dye) and then aligning it. The thickness of the polarizer is not particularly limited, but is usually about 5 to 80 μm.

A polarizer obtained by uniaxially stretching a polyvinyl alcohol-based film dyed with iodine, for example, can be produced by dipping polyvinyl alcohol in an aqueous solution of iodine, dyeing it, and stretching it to 3 to 7 times its original length . If necessary, it may be immersed in an aqueous solution containing boric acid, potassium iodide, or the like. In addition, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. Washing the polyvinyl alcohol-based film with water not only removes dirt and anti-blocking agents on the surface of the polyvinyl alcohol-based film, but also prevents unevenness such as staining by swelling the polyvinyl alcohol-based film. Stretching may be performed after dyeing with iodine, stretching may be performed while dyeing, or dyeing with iodine may be performed after stretching. Stretching may also be performed in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.

Among the protective films provided on one or both sides of the above-mentioned polarizer, materials having good properties in terms of transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like are preferable. As the material of the above-mentioned protective film, for example, polyester-based polymers such as polyethylene terephthalate or polyethylene naphthalate; cellulose-based polymers such as diacetyl cellulose or triacetyl cellulose; Polymers; Acrylic polymers such as polymethyl methacrylate; Styrenic polymers such as polystyrene or acrylonitrile-styrene copolymer (AS resin); Polycarbonate polymers, etc. In addition, examples of polymers that form the protective film include polyethylene, polypropylene, polyolefins having a ring system or norbornene structure, polyolefin-based polymers such as ethylene-propylene copolymers; vinyl chloride Nylon or aromatic polyamide and other amide polymers; imide polymers; sulfone polymers; polyethersulfone polymers; polyether ether ketone polymers; polyphenylene sulfide polymers ; Vinyl alcohol-based polymers, vinylidene chloride-based polymers; polyvinyl butyral-based polymers; arylate-based polymers; polyoxymethylene-based polymers; epoxy-based polymers; mixture etc. In addition, acrylic, urethane, acrylic urethane, epoxy, silicone, and other thermosetting and ultraviolet curable resins are also exemplified.

In addition, the polymer film described in Japanese Unexamined Patent Publication No. 2001-343529 (WO 01/37007) can be exemplified by (A) a thermoplastic resin having a substituted and/or unsubstituted imino group in a side chain, and (B) A resin composition of a thermoplastic resin having substituted and/or unsubstituted phenyl and nitrile groups in side chains. As a specific example, a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleic anhydride imide, and an acrylonitrile-styrene copolymer is exemplified. As the film, a film composed of a mixed extrusion product of a resin composition or the like can be used.

From the viewpoint of polarizing properties, durability, etc., a protective film that can be used particularly preferably is a triacetyl cellulose film whose surface is saponified with alkali or the like. The transparent protective layer may have any thickness, but is generally preferably 500 μm or less, more preferably 1 to 300 μm, and particularly preferably 5 to 300 μm for the purpose of thinning the polarizer. However, when a protective film is provided on both sides of the polarizer, a transparent protective film whose inner and outer sides are made of different polymers or the like can be used.

In addition, it is best not to color the transparent protective film. Therefore, it is preferable to use the film thickness direction represented by Rth=(nx-nz) d (where nx is the refractive index in the direction of the slow axis in the film plane, nz is the refractive index in the film thickness direction, and d is the film thickness). A protective film with a retardation value of -90nm to +75nm. By using such a protective film having a retardation value (Rth) in the thickness direction of -90 nm to +75 nm, coloring (optical coloring) of the polarizing plate caused by the protective film can be substantially eliminated. The retardation value (Rth) in the thickness direction is more preferably -80 nm to +60 nm, particularly preferably -70 nm to +45 nm.

The adhesion between the polarizer and the protective film is usually by means of a water-based adhesive. Examples of the water-based adhesive include polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based, water-based polyurethane, and water-based polyester.

As the above-mentioned protective film, a protective film subjected to hard coating, anti-reflection treatment, anti-sticking, treatment for the purpose of diffusion or anti-glare can also be used.

The purpose of the hard coat treatment is to prevent damage to the surface of the polarizer, for example, by adding a cured film made of an appropriate ultraviolet curable resin such as acrylic or silicone to the surface of the protective film, which has good hardness and sliding properties. formed in such a way. The purpose of antireflection treatment is to prevent reflection of external light on the surface of the polarizing plate, and it can be accomplished by forming a conventional antireflection film or the like. In addition, anti-blocking treatment is performed to prevent sticking to adjacent layers.

In addition, the purpose of implementing anti-glare treatment is to prevent external light from being reflected on the surface of the polarizer and interfere with the visibility of the transmitted light of the polarizer. It is formed by imparting a fine concave-convex structure to the surface of the protective film using an appropriate method such as a method. As fine particles contained in the formation of the surface fine uneven structure, for example, particles made of silicon dioxide, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, cadmium oxide, Transparent particles such as conductive inorganic fine particles composed of antimony oxide or the like, and organic fine particles composed of cross-linked or uncross-linked polymers. When forming the surface fine uneven structure, the amount of fine particles used is usually about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin for forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer that diffuses light transmitted through the polarizer to widen the viewing angle (viewing angle widening function, etc.).

In addition, the anti-reflection layer, anti-adhesion layer, diffusion layer or anti-glare layer can be provided on the protective film itself, or can be used as other optical layers, which are arranged separately from the transparent protective film.

The above polarizing plate can be used as an elliptically polarizing plate or a circular polarizing plate formed by laminating retardation plates. The above-mentioned elliptically polarizing plate or circular polarizing plate will be described. They can change linearly polarized light into elliptically polarized light or circularly polarized light, or change elliptically polarized light or circularly polarized light into linearly polarized light, or change the polarization direction of linearly polarized light through the retardation plate. In particular, as a retardation plate that changes linearly polarized light into circularly polarized light or vice versa, a so-called 1/4 wavelength plate (also referred to as a λ/4 plate) can be used. A 1/2 wavelength plate (also known as a λ/2 plate) is usually used in the case of changing the polarization direction of linearly polarized light.

The elliptically polarizing plate can be effectively used in the case, etc., of compensating (preventing) the coloring (blue or yellow) of a super twisted nematic (STN) type liquid crystal display device due to the birefringence of the liquid crystal layer, thereby performing the above-mentioned non-coloring The situation shown in black and white. In addition, a polarizing plate that controls the three-dimensional refractive index can also compensate (prevent) coloring that occurs when viewing the screen of a liquid crystal display device from an oblique direction, and is therefore preferable. The circular polarizing plate can be effectively used, for example, to adjust the color tone of an image of a reflective liquid crystal display device for displaying a color image, and also has a function of preventing reflection.

In the phase difference plate, for example, various wavelength plates or members for compensating for coloring or viewing angle caused by the birefringence of the liquid crystal layer can be used, and two or more types of phase difference suitable for the purpose of use can also be stacked. Optical characteristics such as retardation are controlled by retardation plate. Examples of retardation plates include polycarbonate, norbornene-based resins, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene or other polyolefins, polyarylates, polyamides, etc. A birefringent film formed by stretching a film made of a suitable polymer, an alignment film composed of a liquid crystal material such as a liquid crystal polymer, a member supporting an alignment layer of a liquid crystal material with a film, etc.

In addition, as a viewing angle compensation film, it can be laminated on a polarizing plate and used as a wide viewing angle polarizing plate. The viewing angle compensation film is a film used to widen the viewing angle to make the image look clear even when the liquid crystal display screen is viewed from a slightly oblique direction that is not perpendicular to the screen.

As such a viewing angle compensating retardation plate, a birefringent film that is additionally subjected to biaxial stretching treatment or stretching treatment in two directions perpendicular to each other, or a birefringent film such as an obliquely oriented film can be used. film etc. As an oblique orientation film, for example, after bonding a heat-shrinkable film on a polymer film, under the action of the shrinkage force formed by heating, the polymer film is stretched or/and shrink-treated, and the liquid crystal is polymerized. materials with oblique orientation, etc. The viewing angle compensation film can be appropriately combined for the purpose of preventing coloring or the like due to a change in the viewing angle due to a phase difference caused by a liquid crystal cell, expanding a viewing angle with good visibility, and the like.

In addition, from the viewpoint of achieving a wide viewing angle with good visibility, it is preferable to use a triacetyl cellulose film to support an optically isotropic layer composed of an alignment layer of a liquid crystal polymer, especially an oblique alignment layer of a discotic liquid crystal polymer. Optically compensated retardation plate made of anisotropic layers.

In addition to the above, there is no particular limitation on the optical layer to be laminated in actual use. For example, one or two layers of thin films used as optical layers in the formation of liquid crystal display devices such as reflective plates and semi-transmissive plates can be used. above. A particularly preferable polarizing plate is a reflective polarizing plate or a semi-transmitting polarizing plate in which a reflecting plate or a semi-transmitting reflecting plate is further laminated on an elliptical polarizing plate or a circular polarizing plate; or a brightness-improving film is further laminated on a polarizing plate. polarizer.

A reflective polarizer is formed by providing a reflective layer on the polarizer, and can be used to form a type of liquid crystal display device that reflects incident light incident from the viewing side (display side) to display, and can omit a light source such as a built-in backlight , thus having advantages such as easy thinning of the liquid crystal display device. When forming a reflective polarizer, it can be carried out by an appropriate method such as a method of providing a reflective layer made of metal or the like on one side of the polarizer through a transparent protective layer or the like as necessary.

Specific examples of reflective polarizers include polarizers in which a reflective layer is formed by attaching a foil or vapor-deposited film of a reflective metal such as aluminum to one surface of a matte-treated protective film as necessary. In addition, a reflective polarizing plate in which the protective film contains fine particles to form a fine uneven structure on the surface, and has a reflective layer with the fine uneven structure thereon, and the like. The reflective layer of the above-mentioned fine uneven structure diffuses incident light by diffuse reflection, thereby preventing orientation and shiny appearance, and has the advantage of suppressing unevenness of light and shade. In addition, the transparent protective film containing particles also has the advantage of further suppressing the unevenness of light and shade through diffusion when incident light and its reflected light pass through it. The formation of the reflective layer of the micro-concave-convex structure that reflects the surface micro-concave-convex structure of the protective film can be formed on the transparent protective layer by appropriate methods such as vacuum evaporation, ion plating, and sputtering, such as evaporation or plating. The method of attaching metal directly on the surface of the surface, etc.

Instead of directly attaching the reflector to the protective film of the polarizer, a reflective layer may be formed on an appropriate film based on the transparent film to form a reflector or the like, and then used. In addition, since the reflective layer is usually made of metal, it is preferable to use a protective film or a polarizing film from the viewpoint of preventing a decrease in reflectivity due to oxidation, maintaining the initial reflectivity for a long time, and avoiding an additional protective layer. A form of use that covers the reflective surface with a sheet or the like.

In addition, in the above, the semi-transmissive polarizing plate can be obtained by making a semi-transmissive reflective layer such as a half-mirror that reflects light with a reflective layer and transmits light. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and can form a liquid crystal display device or the like of a type in which, when the liquid crystal display device or the like is used in a relatively bright environment, the reflection is from the viewing side (display In a relatively dark environment, an image is displayed using a built-in light source such as a backlight built into the back of the transflective polarizer. That is, the transflective polarizing plate is useful in the formation of liquid crystal display devices of the type that can save the energy of using a light source such as a backlight in a bright environment, and can use a built-in light source in a relatively dark environment. It is very useful in the formation of liquid crystal display devices and the like.

A polarizing plate and a brightness improving film bonded together are usually used after being installed on the back side of a liquid crystal cell. The brightness improving film is a film that exhibits the property of reflecting linearly polarized light with a predetermined polarization axis or circularly polarized light with a predetermined direction when natural light enters due to the backlight of a liquid crystal display device or the like or reflection from the back side, etc. and allow other light to pass through. Therefore, the polarizing plate formed by laminating the brightness-improving film and the polarizing plate can allow the light from a light source such as a backlight to enter, and obtain transmitted light in a prescribed polarization state. At the same time, light other than the prescribed polarization state cannot be transmitted. be reflected. The light reflected on the surface of the brightness-improving film is reversed again by means of a reflective layer arranged on its back side, and it is incident on the brightness-improving film again, so that part or all of it is transmitted as light in a specified polarization state. By doing this, the light transmitted through the brightness improving film is increased, and at the same time, the polarized light that is difficult to absorb is supplied to the polarizer, thereby increasing the amount of light that can be used in displaying liquid crystal display images, etc., and thus the brightness can be improved. That is, in the case where light is incident through the polarizer from the back side of the liquid crystal cell with a backlight or the like without using the brightness improving film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is basically received by the polarizer. Absorbs and therefore cannot pass through polarizers. That is, although it varies depending on the characteristics of the polarizer used, about 50% of the light is absorbed by the polarizer. Therefore, the amount of light that can be used in liquid crystal image display, etc. decreases, resulting in dark images. Since the brightness improvement film repeatedly performs the following operations, that is, the light with a polarization direction that can be absorbed by the polarizer is not incident on the polarizer, but the light is reflected on the brightness improvement film, and then by means of the The reflective layer etc. on the side completes inversion, so that the light is incident on the brightness improving film again, so that the brightness improving film only changes the polarization direction of the light reflected and reversed between the two to pass through the polarizer. Since the polarized light in the polarization direction is transmitted and supplied to the polarizer, light such as a backlight can be effectively used for displaying images on the liquid crystal display device, thereby making the screen bright.

It is also possible to provide a diffusion plate between the brightness improving film and the reflective layer or the like. The light in the polarized state reflected by the brightness improving film is directed toward the reflective layer and the like, and the diffuser is provided to uniformly diffuse the passing light while canceling the polarized state into a non-polarized state. That is, the diffuser returns the polarized light to its original natural light state. Repeatedly, the light in the non-polarized state, that is, the natural light state, is irradiated to the reflective layer, etc., reflected by the reflective layer, and then passes through the diffusion plate again and is incident on the brightness improving film. By installing a diffuser between the brightness improving film and the above-mentioned reflective layer, etc., which restores the polarized light to its original natural light state, it is possible to maintain the brightness of the display screen while reducing the brightness unevenness of the display screen, thereby providing uniform and bright lighting. screen. By arranging such a diffuser plate, the number of repeated reflections of the initial incident light can be appropriately increased, and a uniform and bright display image can be provided by utilizing the diffusion function of the diffuser plate.

As the brightness improving film, for example, a dielectric multilayer film or a film multilayer laminate having different refractive index anisotropy, which exhibits the property of transmitting linearly polarized light with a predetermined polarization axis and reflecting other light, can be used. Films, alignment films of cholesteric liquid crystal polymers, or films supporting the alignment liquid crystal layer on a film substrate, which reflect either left-handed or right-handed circularly polarized light and transmit other light Suitable films such as films with special properties.

Therefore, in the brightness improving film of the above-mentioned type that transmits linearly polarized light with a predetermined polarization axis, by making the transmitted light directly incident on the polarizer along the direction coincident with the polarization axis, it is possible to suppress damage caused by the polarizer. While absorbing the loss, the light can be transmitted efficiently. On the other hand, in a brightness-improving film of a type that transmits circularly polarized light, such as a cholesteric liquid crystal layer, although it is possible to directly make light incident on a polarizer, it is preferable to use a phase filter from the viewpoint of suppressing absorption loss. The circularly polarized light is linearly polarized by the difference plate, and then incident on the polarizer. Furthermore, by using a 1/4 wavelength plate as the retardation plate, it is possible to convert circularly polarized light into linearly polarized light.

Regarding the phase difference plate that can function as a 1/4 wavelength plate in a wide wavelength range such as the visible light region, for example, it can be obtained in the following manner, that is, a light-colored light with a wavelength of 550nm can function as a 1/4 wavelength plate. A retardation layer and a retardation layer exhibiting other retardation characteristics, such as a retardation layer that can function as a 1/2 wavelength plate, are superimposed. Therefore, the retardation plate disposed between the polarizing plate and the brightness improving film may be composed of one or more retardation layers.

In addition, for the cholesteric liquid crystal layer, it is also possible to combine materials with different reflection wavelengths to form an arrangement structure in which two or more layers overlap, thereby obtaining a member that reflects circularly polarized light in a wide wavelength range such as the visible light region. , so that transmitted circularly polarized light in a wider wavelength range can be obtained based on this.

In addition, the polarizing plate may be composed of a laminated polarizing plate and two or more optical layers, like the polarized light separation type polarizing plate. Therefore, a reflection type elliptically polarizing plate or a semi-transmitting type elliptically polarizing plate combined with the aforementioned reflective polarizing plate or semi-transmitting polarizing plate and a retardation plate may be used.

The above-mentioned elliptically polarizing plate or reflective elliptically polarizing plate is formed by appropriately combining and laminating a polarizing plate or reflective polarizing plate and a retardation plate. Such an elliptically polarizing plate and the like can also be formed by sequentially and independently laminating a (reflective) polarizing plate and a retardation plate in a manufacturing process of a liquid crystal display device to constitute a combination of a (reflecting) polarizing plate and a retardation plate, and in When pre-laminated as an optical film such as an elliptically polarizing plate, it is excellent in quality stability, lamination workability, etc., and thus has the advantage of improving the production efficiency of liquid crystal display devices and the like.

An adhesive layer may also be provided on the optical film of the present invention. The adhesive layer can be used for the lamination of the optical layer in addition to the adhesion on the liquid crystal cell. When bonding the above-mentioned optical films, their optical axes can be adjusted to an appropriate arrangement angle according to the intended retardation characteristics and the like.

The adhesive for forming the adhesive layer is not particularly limited, and for example, acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine-based or rubber-based polymers, etc. can be suitably selected and used. Adhesives based on polymers. It is particularly preferable to use an adhesive that has excellent optical transparency like an acrylic adhesive, exhibits moderate wettability, cohesiveness, and adhesive properties, and is excellent in weather resistance, heat resistance, and the like.

Moreover, in addition to the above, from the prevention of foaming phenomenon or peeling phenomenon due to moisture absorption, the reduction of optical characteristics due to thermal expansion difference, or the warping of liquid crystal cells, and further from the high quality and excellent durability of liquid crystal display devices From the viewpoint of formability and the like, an adhesive layer with a low moisture absorption rate and excellent heat resistance is preferable.

The adhesive layer can contain, for example, natural or synthetic resins, especially tackifying resins, or fillers, pigments, colorants, antioxidants, etc. made of glass fibers, glass beads, metal powder, other inorganic powders, etc. can be added to the adhesive layer. Additives in the adhesive layer. In addition, an adhesive layer or the like which contains fine particles and exhibits light diffusing properties may also be used.

When attaching the pressure-sensitive adhesive layer to one side or both sides of the optical film, it can be carried out by an appropriate method. As an example, the following method can be mentioned, that is, about 10 to 40 wt. % of the adhesive solution, and then directly attach it to the polarizer or the optical film through a suitable spreading method such as a casting method or a coating method; or form an adhesive layer on the separator based on the above The method of transferring and pasting on a polarizing plate or an optical film, etc.

The adhesive layer can also be provided on one or both surfaces of a polarizing plate or an optical film as a laminated layer of layers of different compositions or types. In addition, when provided on both sides, the inside and outside of the polarizing plate or optical film may be adhesive layers of different compositions, types, thicknesses, and the like. The thickness of the adhesive layer can be appropriately determined according to the purpose of use, the adhesive force, etc., and is generally 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

The exposed surface of the adhesive layer may be temporarily covered with a spacer in order to prevent contamination or the like before use. This prevents contact with the adhesive layer in normal operating conditions. As the spacer, on the basis of satisfying the above-mentioned thickness conditions, for example, plastic films, rubber sheets, paper, cloth, Conventionally, suitable separators such as non-woven fabrics, nets, foamed sheets, metal foils, and laminates thereof, which have been coated with suitable sheets, are suitable.

Also, in the present invention, it is also possible to use, for example, salicylate-based compounds or benzophenol (benzophenol ) series compounds, benzotriazole-based compounds, cyanoacrylate-based compounds, nickel complex compounds and other ultraviolet absorbers, etc., to make them have ultraviolet absorbing ability and the like.

The optical film of the present invention can be preferably used for formation of various devices such as liquid crystal display devices, and the like. A liquid crystal display device can be formed by a conventional method. That is, in general, a liquid crystal display device can be formed by appropriately combining components such as a liquid crystal cell, an optical film, and an illumination system added as needed, and incorporating a driving circuit. In the present invention, in addition to using the optical film of the present invention Other than that, it is not particularly limited, and can be formed according to a conventional method. For the liquid crystal cell, for example, any type of liquid crystal cell such as TN type, STN type, or π type can be used.

Suitable liquid crystal display devices, such as a liquid crystal display device in which the above-mentioned optical film is arranged on one side or both sides of a liquid crystal cell, and a device using a backlight or a reflector in an illumination system, can be formed. At this time, the optical film of the present invention can be provided on one side or both sides of the liquid crystal cell. When the optical films are provided on both sides, they may be the same or different. In addition, when forming a liquid crystal display device, one or more layers such as a diffusion plate, an anti-glare layer, an anti-reflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, etc. Lights and other suitable components.

Next, an organic electroluminescent device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light-emitting layer, and a metal electrode are sequentially stacked on a transparent substrate to form a luminous body (organic electroluminescent body). Here, the organic light-emitting layer is a laminate of various organic thin films. For example, a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light-emitting layer made of a fluorescent organic solid such as anthracene is known, or A laminate of such a light-emitting layer and an electron injection layer made of a perylene derivative or the like, or a laminate of these hole injection layers, a light-emitting layer, and an electron injection layer can be combined in various ways.

The organic EL display device emits light according to the principle that holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by the recombination of these holes and electrons excites the fluorescent substance , When the excited fluorescent substance returns to the ground state, it will emit light. The recombination mechanism in the middle is the same as that of a general diode, and it can be presumed from this that the current and luminous intensity show strong nonlinearity with rectification with respect to the applied voltage.

In an organic EL display device, at least one electrode must be transparent in order to extract light generated in the organic light-emitting layer, and a transparent electrode made of a transparent conductor such as indium tin oxide (ITO) is usually used as an anode. On the other hand, in order to facilitate electron injection and improve luminous efficiency, it is very important to use a substance with a small work function on 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 composed of an extremely thin film with a thickness of about 10 nm. Therefore, like the transparent electrode, the organic light-emitting layer transmits light almost completely. As a result, when the light is not emitted, the light incident from the surface of the transparent substrate and transmitted through the transparent electrode and the organic light-emitting layer and reflected on the metal electrode will be emitted to the surface side of the transparent substrate again. Therefore, when it is recognized from the outside, the organic EL The display surface of the device is like a mirror.

In an organic EL display device comprising an organic electroluminescent body as described below, a polarizing plate may be provided on the surface side of the transparent electrodes, and a phase difference plate may be provided between these transparent electrodes and the polarizing plate. It is formed by providing a transparent electrode on the front side of the organic light-emitting layer that emits light by applying a voltage, and providing a metal electrode on the back side of the organic light-emitting layer.

Since the retardation plate and the polarizing plate have the function of polarizing the light incident from the outside and reflected by the metal electrode, the mirror surface of the metal electrode cannot be recognized from the outside by the polarization function. In particular, when a 1/4 wavelength plate is used to form the retardation plate and the angle between the polarization directions of the polarizer and the retardation plate is adjusted to π/4, the mirror surface of the metal electrode can be completely shielded.

That is, of the external light incident on the organic EL display device, only the linearly polarized light component is transmitted due to the existence of the polarizing plate. The linearly polarized light is generally converted into elliptically polarized light by the phase difference plate, and when the phase difference plate is a 1/4 wavelength plate and the angle between the polarization direction of the polarizer and the phase difference plate is π/4, it becomes circularly polarized light .

The circularly polarized light passes through the transparent substrate, transparent electrode, and organic thin film, is reflected on the metal electrode, and then passes through the organic thin film, transparent electrode, and transparent substrate again, and is converted into linearly polarized light by the phase difference plate again. Then, since the linearly polarized light is perpendicular to the polarization direction of the polarizer, it cannot pass through the polarizer. As a result, the mirror surface of the metal electrode can be completely shaded.

Example

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

<Preparation of liquid crystal material coating liquid>

Prepared by dissolving 10 g of a liquid crystal monomer (manufactured by BASF, Paliocolor LC242) showing a nematic liquid crystal phase and 3 g of a photopolymerization initiator (manufactured by Chiba Specialty Chemicals, Irgacure 907) (para-polymerizable liquid crystal compound) in 40 g of toluene solution.

<Peel force>

A surface protection sheet (150 mm x 50 mm) was bonded to a cellulose triacetate film, and after standing at 23° C. for 20 minutes, the peeling at 180° was measured with a tensile tester (manufactured by Orientec Co., Ltd., Tensilon). , The force (N/50mm) when the surface protection sheet is peeled off at a speed of 300mm/min.

<Confirmation of charged state>

Unlike the obtained liquid crystal aligning film, the charged state was confirmed immediately after peeling off the surface protection sheet from the transparent base film. Immediately after peeling off the surface protection sheet from the transparent base film, it was confirmed that after the positively charged blue toner and the negatively charged red toner were sprinkled on the surface of the transparent base film, the surrounding adhesion was removed. The color distribution of the attached toner was confirmed visually. When only the blue toner is attached, it can be judged that the surface is uniformly negatively charged; when only the red toner is attached, it can be judged that the surface is uniformly positively charged. In the case where the red toner and the blue toner are mixed, it can be judged that the charged state of the surface is not uniform. In Example 1, a photograph showing the color distribution of the attached toner as a judgment object is shown in FIG. 1 , and a photograph concerning Comparative Example 2 is shown in FIG. 2 .

Example 1

After the surface of the triacetyl cellulose film was oriented by rubbing with a rayon cloth, a surface protection sheet with a peeling force of 0.05 N/50 mm was attached immediately. As a surface protection sheet, Sekisui Chemical Co., Ltd. product 6221F was used. It is produced by co-extruding the substrate layer (thickness 50μm, polyethylene) and the adhesive layer (ethylene-ethyl acetate copolymer) of the surface protection sheet. Next, the surface protection sheet was peeled off (180° peeling) immediately before the liquid crystal material coating liquid was applied, and the coating liquid was coated on the alignment-treated surface using a spinning bar #10. Dry at 90°C for 5 minutes to align the liquid crystal material, then irradiate the light of 1mJ/ ^cm2 with a metal halide lamp to solidify the liquid crystal layer and obtain a liquid crystal alignment film with a thickness of 2μm.

Example 2

In Example 1, except having used the surface protection sheet whose peeling force was 0.1N/50mm, it carried out similarly to Example 1, and obtained the liquid crystal aligning film. As the surface protection sheet, Santect PAC3 manufactured by Sane Chemical Co., Ltd. was used. It is produced by co-extruding the substrate layer (thickness 60 μm, polyethylene) and the adhesive layer (ethylene-ethyl acetate copolymer) of the surface protection sheet.

Example 3

In Example 1, except having used the surface protection sheet whose peeling force was 0.3 N/50mm, it carried out similarly to Example 1, and obtained the liquid crystal aligning film.

Comparative example 1

In Example 1, except not using a surface protection sheet, it carried out similarly to Example 1, and obtained the liquid crystal alignment film. In Comparative Example 1, the contact between the triacetylcellulose film and the roll was seen.

Comparative example 2

In Example 1, except having used the surface protection sheet whose peeling force was 1.5 N/50mm, it carried out similarly to Example 1, and obtained the liquid crystal aligning film. As the surface protection sheet, Y-16F manufactured by SunE-Chem Co., Ltd. was used.

Comparative example 3

In Example 1, except having used the surface protection sheet whose peeling force was 1.0 N/50mm, it carried out similarly to Example 1, and obtained the liquid crystal aligning film. As the surface protection sheet, E-MASK manufactured by Nitto Denko Co., Ltd. was used.

The following evaluation was performed about the liquid crystal aligning film obtained by the Example and the comparative example. The results are shown in Table 1.

(orientation)

Two polarizing plates (SEG1425DU) manufactured by Nitto Denko were prepared in a perpendicular state, and the liquid crystal alignment film (retardation plate) prepared above was arranged between them so that the rubbing direction was aligned with the absorption axis of one polarizing plate ( or through the axis) consistent. On the other hand, the transmittance Y (%) was measured with DOT-3 manufactured by Murakami Color Co., Ltd. When the rubbed orientation angle was disturbed, it was confirmed that the transmittance increased and the orientation decreased. If the transmittance is 0.1% or less, it can be judged that the liquid crystal is in a state of being aligned uniformly in the rubbing direction, and it is rated as good. Otherwise it is bad.

Table 1 surface protection sheet charged state Orientation with or without Peel force (N/50mm) Transmittance (%) judge Example 1 have 0.05 Only the blue toner is attached/negatively charged 0.05 good Example 2 have 0.1 Only the blue toner is attached/negatively charged 0.07 good Example 3 have 0.3 Only the blue toner is attached/negatively charged 0.06 good Comparative example 1 none - Mixed presence of red toner and blue toner/uneven charging 0.25 bad Comparative example 2 have 1.5 Mixed presence of red toner and blue toner/uneven charging 1.24 bad Comparative example 3 have 1.0 Mixed presence of red toner and blue toner/uneven charging 1.86 bad

Claims (8)

1. the manufacture method of a liquid crystal aligning film is characterized in that, comprising:

By the operation (1) of friction to the processing of transparent base film implementation orientation,

With peeling force is the operation (2) that surface protective plate below the 0.5N/50mm fits in described orientation process face,

Peel off described surface protective plate applies the liquid crystal material that contains liquid crystal monomer and/or liquid crystal polymer afterwards on described orientation process face operation (3),

Carry out immobilized operation (4) after making described liquid crystal material orientation.

2. the manufacture method of liquid crystal aligning film according to claim 1 is characterized in that,

Surface protective plate has substrate layer and bonding coat, is by their co-extruded being gone out or by the surface protective plate made of coating bonding coat on substrate layer.

3. the manufacture method of liquid crystal aligning film according to claim 2 is characterized in that,

Substrate layer contains the ethylene series resin, and bonding coat contains ethene-vinyl acetate co-polymer.

4. according to the manufacture method of any described liquid crystal aligning film in the claim 1～3, it is characterized in that,

During the peeling off of the surface protective plate in carrying out operation (3), transparent base film evenly has any electric charge in the plus or minus electric charge.

5. a liquid crystal aligning film is characterized in that,

Be that manufacture method by any described liquid crystal aligning film in the claim 1～4 obtains.

6. an optical thin film is characterized in that,

At least use 1 described liquid crystal aligning film of claim 5.

7. an image display device is characterized in that,

Use the described optical thin film of claim 6.

8. a surface protective plate is characterized in that,

Be in the manufacture method of the described liquid crystal aligning film of claim 1～4, be used for operation (2) and peeling force be surface protective plate below the 0.5N/50mm.

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