KR20200024096A - Aligned liquid crystal film and production method thereof, optical film with pressure-sensitive adhesive and production method thereof, and image display device - Google Patents

Abstract

An aligned liquid crystal film comprises a liquid crystal layer which is aligned in a predetermined direction and two or more compounds. The aligned crystal film includes at least one photopolymerizable liquid crystal compound. The aligned crystal film is recommended to have a maximum horizontal load between a predetermined range when the aligned crystal film has a height between 15 nm and 30 nm from the surface. The aligned liquid crystal film is formed by coating at least one photopolymerizable liquid crystal compound and a liquid crystal composition including another compound on a film substrate and aligning crystal molecules in a predetermined direction, and polymerizing or crosslinking the liquid crystal compound.

Description

 Aligned liquid crystal film and production method, and optical display with pressure-sensitive adhesive and production method, and image display device

The present invention relates to an alignment liquid crystal film in which liquid crystal molecules are aligned, a method of manufacturing the same, and an image display device including the alignment liquid crystal film. Moreover, this invention relates to the optical film with an adhesive provided with an adhesive layer in one side of an orientation liquid crystal film, and its manufacturing method.

As an optical film which has functions, such as optical compensation of a liquid crystal display device and prevention of external light reflection of an organic electroluminescent element, the liquid crystal film (orientation liquid crystal film) which a liquid crystal compound orientates in the predetermined direction is used. An oriented liquid crystal film is advantageous in thickness reduction and weight reduction because birefringence is large compared with the stretched film of a polymer.

When using a thermotropic liquid crystal, an oriented liquid crystal film is obtained by apply | coating a liquid crystalline composition (solution) on a board | substrate, heating so that the compound contained in a composition may become a liquid crystal state, and then cooling and fixing an orientation. When a liquid crystalline composition contains the liquid crystal compound (liquid crystal monomer) which has photopolymerizability, stability can be improved by superposing | polymerizing or bridge | crosslinking a liquid crystal monomer by light irradiation after cooling.

A liquid crystal compound can orientate liquid crystal molecules to a predetermined direction by the shear force at the time of apply | coating on a board | substrate, the orientation regulation force of an orientation film, etc., and the orientation liquid crystal film which has various optical anisotropy is obtained. For example, the homeotropic oriented liquid crystal film which orientated the liquid crystal molecule which has positive refractive index anisotropy in the normal direction (thickness direction) of a film plane has the refractive index (ideal light refractive index) nz of the thickness direction which is the orientation direction of liquid crystal molecules. It can be used as a positive C plate larger than in-plane refractive index (normal refractive index) nx and ny, and having refractive index anisotropy of nz> nx = ny.

Since spontaneous homeotropically oriented materials are very limited, in the production of homeotropic oriented liquid crystal films, a substrate having a vertical alignment film is generally used. Patent document 1 uses a side chain type liquid crystal polymer having a monomer unit containing a liquid crystalline fragment side chain and a monomer unit containing a non-liquid crystalline fragment side chain, and a substrate having no vertical alignment film by using a composition containing a photopolymerizable liquid crystal monomer. It discloses that a homeotropic oriented liquid crystal film can be formed on it. Patent Document 1 describes that the non-liquid crystalline fragment side chain of the liquid crystal polymer is considered to have a function of promoting homeotropic alignment.

An image display apparatus is obtained by bonding an oriented liquid crystal film together with optical films, such as a polarizing plate, to the surface of an image display cell. An adhesive is generally used for bonding of the orientation liquid crystal film to an image display cell. When bonding an optical film to an image display cell via an adhesive, defects, such as mixing of a bubble and a shift of a bonding position, may arise. Moreover, after bonding an optical film to an image display cell, the defect resulting from the fault of an optical film, etc. may be detected. When such a defect has occurred, the operation (rework) which peels an optical film from an image display cell is performed.

Japanese Patent No. 4174192

Higher durability is required for an image display device, and an optical film is required not to be peeled from an image display cell even under severe conditions such as exposure to a high temperature, high humidity environment for a long time, or a drop impact test. By using the adhesive with high adhesive force for bonding of an image display cell and an optical film, peeling of the optical film from an image display cell can be suppressed in the use environment of an image display apparatus.

On the other hand, when the adhesive with high adhesive strength is used, a large peeling force is required at the time of rework, and problems such as the residual (residual glue) of the adhesive on the surface of the image display cell and the peeling (interlayer peeling) between the layers of the optical film are required. (Rework failure) may occur. In particular, when the optical film contains an alignment liquid crystal film, cohesive failure of the alignment liquid crystal film is likely to occur due to a large peeling force at the time of reworking, whereby rework defects due to remaining grass or interlayer peeling are likely to occur. It turned out by the inventor's examination.

In view of the above, an object of the present invention is to provide an alignment liquid crystal film in which the occurrence of rework defects is suppressed when bonded to an image display cell via an adhesive.

In view of the above, as a result of the present inventors examining, when the ratio of the horizontal load at a predetermined depth from the surface is within a predetermined range, the cohesive failure of the alignment liquid crystal film is less likely to occur, and when bonded to an image display cell via an adhesive. The inventors found that rework failure can be suppressed, and the present invention has been reached.

This invention relates to the orientation liquid crystal film which consists of a liquid crystal layer which liquid crystal molecules orientated in the predetermined direction, and its manufacturing method. An orientation liquid crystal film contains 2 or more types of compounds, At least 1 type is a polymer of a photopolymerizable liquid crystal compound.

A polymer is mentioned as an example of the other compound contained in an orientation liquid crystal film. As an example of a polymer, a side chain type liquid crystal polymer is mentioned. For example, an orientation liquid crystal film contains a side chain type liquid crystal polymer which has the monomer unit containing a liquid crystalline fragment side chain, and the monomer unit containing a non-liquid crystalline fragment side chain in addition to the polymer of a photopolymerizable liquid crystal compound. The homeotropic orientation of the compound is promoted, and a homeotropic oriented liquid crystal film is obtained.

The orientation liquid crystal film containing the polymer of a photopolymerizable liquid crystal compound is a liquid crystal composition containing a photopolymerizable liquid crystal compound and a compound which does not have photopolymerizable property (for example, said side chain type liquid crystal polymer) on a film substrate, for example. It apply | coats and heats a liquid crystalline composition, orients a liquid crystal molecule to a predetermined direction, and is obtained by superposing | polymerizing or bridge | crosslinking a photopolymerizable liquid crystal compound by light irradiation. As a film substrate, you may use the film in which the orientation film is not provided. The film substrate on which the alignment film is not provided may be a stretched film having an in-plane retardation of 10 to 500 nm.

It is preferable that the orientation liquid crystal film has a maximum horizontal load F ₃₀ at a depth of 30 nm from the surface of ₁ to 2.2 times the maximum horizontal load F ₁₅ at a depth of 15 nm from the surface. For example, the alignment light polymerizable liquid crystal compound by adjusting the amount of irradiation light at the time of polymerization or cross-linking can be adjusted for F ₃₀ / F ₁₅ of the liquid crystal film. The amount of integrated irradiation light when polymerizing or crosslinking the photopolymerizable liquid crystal compound is preferably 100 to 370 mJ / cm ² .

As an use form of the said orientation liquid crystal film, the optical film with an adhesive provided with an adhesive layer in one main surface of an orientation liquid crystal film is mentioned. The optical film with an adhesive may be equipped with the other film bonded together on the other main surface of the orientation liquid crystal film via an adhesive layer.

The optical film with an adhesive provided with the adhesive layer on one side of an orientation liquid crystal film, and the other film bonded together through the adhesive layer on the other side, for example, forms an orientation liquid crystal film on a film substrate, and forms on an alignment liquid crystal film After bonding another film through an adhesive bond layer, it is obtained by peeling a film substrate and laminating | stacking an adhesive layer on an oriented liquid crystal film. The adhesive which bonds an oriented liquid crystal film and another film may be a photocurable adhesive agent.

After the bonding liquid crystal film of the present invention is bonded to an image display cell via an adhesive, cohesive failure is less likely to occur when reworking is performed, and the reworkability is excellent.

It is sectional drawing which shows one form of the optical film with an adhesive.
It is a conceptual diagram which shows an example of the manufacturing process of an optical film with an adhesive.
3 is a cross-sectional view illustrating an example of a laminated structure of an image display device.
It is a graph which shows the relationship of the accumulated light quantity and a horizontal load at the time of preparation of the orientation liquid crystal film of an Example.
It is a TEM cross-sectional observation image of the orientation liquid crystal film of an Example.

The alignment liquid crystal film of this invention consists of a liquid crystal layer which liquid crystal molecules orientated in the predetermined direction. The liquid crystal layer contains two or more kinds of compounds, at least one of which is a polymer of a photopolymerizable liquid crystal compound.

In the alignment liquid crystal film of the present invention, the horizontal load F ₃₀ at a depth of 30 nm from the surface is ₁ to 2.2 times the horizontal load F ₁₅ at a depth of 15 nm from the surface. The horizontal load is a load when the nanoindenter is pushed to a predetermined depth and the indenter is moved relative to the sample in the horizontal direction (direction perpendicular to the depth direction). The horizontal load is an index indicating hardness at a predetermined depth of the sample, and different horizontal loads depending on the pushing depth means that the sample has a hardness distribution in the depth direction.

Alignment liquid crystal film of the present invention F ₃₀ / F ₁₅ that is not more than 2.2, the hardness distribution in the depth direction in the vicinity of the surface is small. Therefore, after bonding an oriented liquid crystal film to an image display cell using an adhesive, when a rework is performed, the cohesive failure of an oriented liquid crystal film hardly arises, and problems, such as remaining glue to an image display cell, (rework poor) Can be suppressed.

1: is sectional drawing which shows one form of the optical film with an adhesive in which the adhesive layer 2 was attached to the orientation liquid crystal film 1. The optical film with an adhesive of FIG. 1 is equipped with the adhesive layer 2 in one main surface of the orientation liquid crystal film 1, and the film 4 bonded together via the adhesive bond layer 3 in the other surface. The separator 9 is attached to the surface of the adhesive layer 2.

2A-2D have shown an example of the manufacturing process of the optical film with an adhesive. First, a liquid crystal composition containing a liquid crystal compound is coated on the film substrate 8, and photopolymerization is performed in a state in which the liquid crystal molecules are aligned in a predetermined direction to fix the alignment state of the liquid crystal molecules on the film substrate 8. The laminated body 10 provided with the orientation liquid crystal film 1 is obtained (FIG. 2A). The surface which contacts the film substrate 8 of the orientation liquid crystal film 1 in this laminated body 10 is called "substrate surface", and the surface on the opposite side is called "air surface."

The film 4 is bonded together to the air surface 12 of the alignment liquid crystal film 1 via the adhesive bond layer 3 (FIG. 2B), and the film substrate 8 is carried out from the board surface 11 of the alignment liquid crystal film 1 ) Is peeled off (FIG. 2C). By laminating the pressure-sensitive adhesive layer 2 on the substrate surface 11 of the alignment liquid crystal film 1 (FIG. 2D), the optical film with the pressure-sensitive adhesive having the pressure-sensitive adhesive layer 2 on the substrate surface 11 of the alignment liquid crystal film 1. A film is obtained.

The optical film with an adhesive is used for formation of an image display apparatus, for example. FIG. 3: is sectional drawing which shows the laminated structure example of the image display apparatus provided with the optical film with an adhesive, and the orientation liquid crystal film 1 is bonded together through the adhesive layer 2 on the surface of the image display cell 50. As shown in FIG. Examples of the image display cell 50 include a liquid crystal cell and an organic EL cell.

[Oriented liquid crystal film]

In the alignment liquid crystal film, liquid crystal molecules are aligned in a predetermined direction, and the alignment state thereof is fixed or consists of a liquid crystal layer. Since the birefringence is significantly larger than the film made of the non-liquid crystal material, the alignment liquid crystal film can significantly reduce the thickness of the optically anisotropic element having a desired retardation. The thickness of the orientation liquid crystal film is about 0.5-7 micrometers, Preferably it is 1-5 micrometers.

The liquid crystal layer contains two or more kinds of compounds, at least one of which is a polymer of a photopolymerizable liquid crystal compound. An oriented liquid crystal film is obtained by apply | coating a liquid crystalline composition on a film board | substrate, heating a liquid crystalline composition, orienting liquid crystal molecules to a predetermined direction, and polymerizing or bridge | crosslinking a liquid crystalline compound by light irradiation.

<Liquid Crystal Composition>

The liquid crystalline composition comprises two or more compounds. The liquid crystalline composition contains at least one photopolymerizable liquid crystal compound. As for the liquid crystalline compound contained in a liquid crystalline composition, it is preferable that a liquid crystal phase is a nematic phase (nematic liquid crystal). The liquid crystalline expression mechanism of the liquid crystal compound may be either lyotropic or thermotropic. In order to obtain a homeotropic oriented liquid crystal film, it is preferable to use a thermotropic liquid crystal.

(Photopolymerizable Liquid Crystal Compound)

The photopolymerizable liquid crystal compound (monomer) has a mesogenic group and at least one photopolymerizable functional group in one molecule. 40-100 degreeC is preferable, as for the temperature (liquid crystal phase transition temperature) which a liquid crystal monomer shows liquid crystallinity, 50-90 degreeC is more preferable, and 55-85 degreeC is still more preferable.

In the preparation of the alignment liquid crystal film, the liquid crystal composition is applied onto a substrate, heated to a liquid crystal phase transition temperature or higher to orient the liquid crystal molecules, and then cooled to below the glass transition temperature to fix the alignment, and irradiated with light to Light curing (polymerization and / or crosslinking) is carried out. The photopolymerizable functional group of a liquid crystal monomer reacts by light irradiation, and the polymer of a photopolymerizable liquid crystal compound is obtained. The polymer after photocuring is non-liquid crystalline and no transition of the liquid crystal phase, glass phase, or crystal phase due to temperature change occurs. Therefore, when photocuring is performed in the state which orientated the liquid crystal monomer to the predetermined direction, the orientation liquid crystal film which is hard to be influenced by a temperature change and excellent in stability is obtained.

As mesogenic group of a liquid crystal monomer, a biphenyl group, a phenyl benzoate group, a phenyl cyclohexane group, an azoxybenzene group, an azomethine group, an azobenzene group, a phenyl pyrimidine group, a diphenyl acetylene group, a diphenyl benzoate group, a bicyclo Cyclic structures, such as a hexane group, a cyclohexyl benzene group, and a terphenyl group, are mentioned. The terminal of these cyclic units may have substituents, such as a cyano group, an alkyl group, an alkoxy group, and a halogen group.

As a photopolymerizable functional group, a (meth) acryloyl group, an epoxy group, a vinyl ether group, etc. are mentioned. Especially, a (meth) acryloyl group is preferable. It is preferable that a photopolymerizable liquid crystal monomer has two or more photopolymerizable functional groups in 1 molecule. By using the liquid crystal monomer containing two or more photopolymerizable functional groups, since a crosslinked structure is introduce | transduced into the liquid crystal layer after photopolymerization, there exists a tendency for the durability of an orientation liquid crystal film to improve.

Arbitrary appropriate liquid crystal monomers can be employ | adopted as a liquid crystal monomer. For example, International Publication No. 00/37585, US Patent No. 5211877, US Patent No. 4388453, International Publication No. 93/22397, European Patent No.0261712, German Patent No. 19504224, German Patent No.4408171, British Patent The polymeric mesogenic compound etc. which were described in 2280445 etc. can be used. As a specific example of a liquid crystal monomer, BASF Corporation "Paliocolor LC242", Merck Corporation "E7", Wacker-Chem Corporation "LC-Sillicon-CC3767", etc. are mentioned, for example.

As a photopolymerizable liquid crystal monomer which has a mesogenic group and some (meth) acryloyl group in 1 molecule, the compound represented by following General formula (IV) is mentioned, for example.

[Formula IV]

In formula (IV), R is a hydrogen atom or a methyl group, A and D are each independently a 1,4-phenylene group or a 1,4-cyclohexylene group, and B is a 1,4-phenylene group, 1,4 -Cyclohexylene group, 4,4'-biphenylene group or 4,4'-bicyclohexylene group, and Y and Z are each independently -COO-, -OCO-, or -O-. g and h are the integers of 2-6 each independently.

(Liquid crystal polymer)

In addition to the liquid crystal monomer, the liquid crystal composition preferably contains a compound for controlling the alignment of the liquid crystal monomer in a predetermined direction. By including the compound which controls the orientation of a liquid crystal monomer in a liquid crystalline composition, even when using the board | substrate which is not equipped with the alignment film, the liquid crystal layer in which the liquid crystal molecule was orientated in the predetermined direction can be formed.

The compound for controlling the orientation of the liquid crystal monomer may be a polymer or a low molecular weight compound. For example, in order to make homeotropic alignment of a liquid crystal monomer, it is preferable that a side chain type liquid crystal polymer is contained in a liquid crystalline composition.

The side chain type liquid crystal polymer may be a homopolymer or a copolymer. The side chain type liquid crystal polymer may include only a monomer unit having a liquid crystalline fragment side chain, or may include a monomer unit having no liquid crystalline fragment in a side chain, in addition to the monomer unit having a liquid crystalline fragment side chain. As a monomer unit which does not have a liquid crystalline fragment in a side chain, the monomer unit which does not have a side chain, and the monomer unit which has a non-liquid crystalline fragment in a side chain are mentioned.

When a polymer has a liquid crystalline fragment in a side chain, liquid crystalline property is expressed and when a liquid crystalline composition is heated to predetermined temperature, there exists a tendency which the orientation of a polymer to a predetermined direction is promoted. In addition, since the polymer has a non-liquid crystalline fragment in the side chain, an orientation force for homeotropically aligning the photopolymerizable liquid crystal monomer included in the liquid crystal composition together with the polymer acts. A homeotropic oriented liquid crystal film is obtained by orienting a liquid crystal monomer in conjunction with the orientation of a side chain type liquid crystal polymer, and fixing this alignment state.

As a monomer which has a liquid crystalline fragment side chain, the polymeric compound which has a nematic liquid crystalline substituent containing a mesogenic group is mentioned. As a mesogenic group, what was illustrated previously as a mesogenic group of a liquid crystal monomer is mentioned. Especially, what has a biphenyl group or a phenylbenzoate group as a mesogenic group is preferable.

As a monomer which has a non-liquid crystalline fragment side chain, the polymeric compound which has linear substituents, such as C7 or more long-chain alkyl, is mentioned. As a polymerizable functional group of a liquid crystalline monomer and a non-liquid crystalline monomer, a (meth) acryloyl group is mentioned, for example.

As the side chain type liquid crystal polymer, a copolymer having a liquid crystalline monomer unit represented by the formula (I) and a non-liquid crystalline monomer unit represented by the formula (II) is preferably used.

[Formula I]

[Formula II]

In formula (I), R ¹ is a hydrogen atom or a methyl group, R ² is a cyano group, a fluoro group, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, X ¹ is -CO _2- Or -OCO-. a is an integer of 1-6, b and c are each independently 1 or 2.

In general formula (II), R <^3> is a hydrogen atom or a methyl group, R <^4> is a C7-C22 alkyl group, a C1-C22 fluoroalkyl group, or group represented by following General formula (III).

[Formula III]

In general formula (III), R <^5> is a C1-C5 alkyl group and d is an integer of 1-6.

Although the ratio of a liquid crystalline monomer unit and a non-liquid crystalline monomer unit in a side chain type liquid crystal polymer is not specifically limited, When there are few ratios of a non-liquid crystalline monomer unit, the photopolymerizable liquid crystal compound according to the orientation of a side chain type liquid crystal polymer is used. Orientation becomes inadequate and the orientation of the liquid crystal layer after photocuring may become nonuniform. On the other hand, when there are few ratios of a liquid crystalline monomer unit, a side chain type liquid crystal polymer will become difficult to show liquid crystal monodomain orientation. Therefore, as for the ratio of the non-liquid crystalline monomer with respect to the sum total of a liquid crystalline monomer unit and a non-liquid crystalline monomer unit, 0.01-0.8 are preferable by molar ratio, 0.1-0.6 are more preferable, and 0.15-0.5 are still more preferable. From a viewpoint of making film formability and orientation of a liquid crystalline composition compatible, about 2000-100000 are preferable and, as for the weight average molecular weight of a side chain type liquid crystal polymer, about 2500-50000 are more preferable.

The side chain type liquid crystal polymer can be polymerized by various known methods. For example, when a monomer unit has a (meth) acryloyl group as a polymerizable functional group, the side chain type liquid crystal polymer which has a liquid crystalline fragment and a non-liquid crystalline fragment is obtained by radical polymerization using light or heat.

(Furtherance)

The ratio of the photopolymerizable liquid crystal compound (monomer) and other compounds in the liquid crystal composition is not particularly limited. It is preferable that content of a photopolymerizable liquid crystal compound is more than content of another compound from a viewpoint of obtaining the highly durable orientation liquid crystal film. In the liquid crystalline composition containing a photopolymerizable liquid crystal compound and a liquid crystal polymer, content (weight) of a photopolymerizable liquid crystal compound is 1.5- of content of a liquid crystal polymer from a viewpoint of obtaining an orientation liquid crystal film with high durability and high orientation uniformity. 15 times is preferable, 2 to 10 times are more preferable, and 2.5 to 6 times are more preferable.

In order to accelerate hardening of the photopolymerizable liquid crystal compound by light irradiation, it is preferable that a liquid crystalline composition contains a photoinitiator. As a photoinitiator, what generate | occur | produces a radical by light irradiation (photo radical generator) is preferable. Content of the photoinitiator in a liquid crystalline composition is about 0.5-20 weight part normally with respect to 100 weight part of photopolymerizable liquid crystal compounds, Preferably it is about 3-15 weight part, More preferably, it is 5-10 weight part It is enough.

A liquid crystalline composition can be prepared by mixing a photopolymerizable liquid crystal compound, another compound (for example, side chain type liquid crystal polymer), and a photoinitiator with a solvent. The solvent is not particularly limited as long as it can dissolve the photopolymerizable liquid crystal compound and does not erode the film substrate (or has low erosion), and it is not particularly limited. Halogenated hydrocarbons such as tetrachloroethylene, chlorobenzene and orthodichlorobenzene; Phenols such as phenol and parachlorophenol; Aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene and 1,2-dimethoxybenzene; Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, and N-methyl-2-pyrrolidone; Ester solvents such as ethyl acetate and butyl acetate; alcohol solvents such as t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol and 2-methyl-2,4-pentanediol; Amide solvents such as dimethylformamide and dimethylacetamide; Nitrile solvents such as acetonitrile and butyronitrile; Ether solvents such as diethyl ether, dibutyl ether and tetrahydrofuran; Ethyl cellosolve, butyl cellosolve, and the like. The concentration of the liquid crystal composition is usually about 3 to 50% by weight, preferably about 7 to 35% by weight.

<Film substrate>

As a board | substrate which apply | coats a liquid crystalline composition, a film board | substrate is used preferably. By using a film board | substrate, since a series of processes from application | coating of the liquid crystalline composition onto a board | substrate to hardening by photopolymerization of a liquid crystal monomer can be performed by roll-to-roll, productivity of an orientation liquid crystal film can be improved. Can be.

The film substrate has a 1st main surface and a 2nd main surface, and a liquid crystalline composition is apply | coated on a 1st main surface. If the resin material which comprises a film board | substrate cannot melt | dissolve in the solvent of a liquid crystalline composition, and has heat resistance at the time of heating for orientating a liquid crystalline composition, it will not restrict | limit especially, Polyester, such as polyethylene terephthalate and a polyethylene naphthalate, ; Polyolefins such as polyethylene and polypropylene; Cyclic polyolefins such as norbornene-based polymers; Cellulose polymers such as diacetyl cellulose and triacetyl cellulose; Acrylic polymers; Styrenic polymers; Polycarbonate, polyamide, polyimide and the like. Especially, since a film which is excellent in the fluidity | liquidity at the time of shaping | molding, and a high smoothness is easy to be obtained, it is especially preferable to use a norbornene-type polymer film as a film substrate. A norbornene-based polymer film is preferable in that the peelability at the time of transferring the alignment liquid crystal film to another film or the like is excellent. Examples of the norbornene-based polymers include ZEONOR manufactured by Japan Xeon, ZEONEX, and Aton manufactured by JSR.

An alignment film may be provided in the film substrate. What is necessary is just to select an oriented film suitably according to the kind of liquid crystal compound, the material of a board | substrate, etc. Examples of the aligning agent for forming the alignment film include organic silanes such as lecithin, stearic acid, hexadecyltrimethylammonium bromide, octadecylamine hydrochloride, monobasic carboxylic acid chromium complex, silane coupling agent and siloxane compound, perfluorodimethylcyclohexane, Tetrafluoroethylene, polytetrafluoroethylene, and the like.

When the liquid crystalline composition contains a compound which promotes the alignment of the liquid crystal in a predetermined direction in addition to the photopolymerizable liquid crystal compound as described above, the homeotropic alignment liquid crystal film is used even when a substrate is not provided with the alignment film. Can be formed. By not requiring the alignment film, the general purpose of the film substrate can be increased, and the process can be simplified and the manufacturing cost can be reduced.

You may use a stretched film as a film substrate. By extending | stretching a film, since unevenness | corrugation, such as a die line at the time of film-forming, is leveled, the smoothness of a film substrate improves and there exists a tendency for arithmetic mean roughness Ra to become small. It is especially preferable to use a biaxially oriented film as the film substrate from the viewpoint of high uniformity of the surface.

An in-plane retardation of the oriented film to be used as the film substrate R ₀ is common to more than 10㎚. When the film substrate is a stretched film having an in-plane retardation of 10 nm or more, the polymer constituting the film is preferentially oriented in a predetermined direction (ground axis direction or fast axis direction). Since the orientation of the polymer of the film substrate has an orientation control force for homogeneous alignment of the liquid crystal molecules, when the vertical alignment film is not provided, the homeotropic alignment of the liquid crystal molecules may be inhibited and an orientation defect may occur. As described later in detail, by lowering the heating temperature at the time of homeotropic alignment of the liquid crystal molecules, a homeotropic alignment liquid crystal film having few orientation defects can be obtained even when a stretched film substrate is used.

When the in-plane retardation of a film substrate is excessively large, the temperature range which can reduce an orientation defect may become narrow, and liquid crystal phase transition within this temperature range may become difficult. Therefore, the in-plane retardation R ₀ of the film substrate is not more than 500㎚ preferably, 300㎚ less are more preferred, the 200㎚ less is more preferred.

Although the thickness of a film substrate is not specifically limited, When handling property etc. are considered, it is about 10-200 micrometers normally. The in-plane birefringence Δn (the value obtained by dividing the in-plane retardation R ₀ by the thickness) of the stretched film is preferably 0.01 or less, more preferably 0.008 or less, and even more preferably 0.006 or less.

3 nm or less is preferable, as for the arithmetic mean roughness Ra of the 1st main surface of a film substrate, 2 nm or less is more preferable, 1.5 nm or less is more preferable. It exists in the tendency for the orientation defect of an orientation liquid crystal film to reduce by Ra being small and apply | coating a liquid crystalline composition to the film substrate surface with high smoothness. As mentioned above, it exists in the tendency for Ra of a film to become small by extending | stretching a film. Therefore, there exists a tendency for the orientation defect of an orientation liquid crystal film to reduce by using a stretched film substrate.

Since the surface shape of the first main surface of the film substrate is transferred to the alignment liquid crystal film formed thereon, Ra of the substrate surface of the alignment liquid crystal film is approximately equal to Ra of the first main surface of the substrate. Therefore, when Ra of a 1st main surface uses a film substrate which is 3 nm or less, Ra of the board | substrate surface of an orientation liquid crystal film also becomes 3 nm or less in many cases. In addition, Ra of the air plane at the time of application | coating of a liquid crystalline composition tends to become smaller than Ra of the board | substrate surface. Therefore, when the film substrate whose Ra of a 1st main surface is 3 nm or less is used, the arithmetic mean roughness of both surfaces of an orientation liquid crystal film will become 3 nm or less in many cases.

In order to make arithmetic mean roughness into the said range, it is preferable that a film substrate does not contain a filler inside. Since the film which does not contain a filler and whose surface smoothness is high has low slipperiness | lubricacy, it may generate blocking, or conveyance defect and winding defect in a roll-to-roll process may occur. In order to prevent blocking, conveyance defects, etc. resulting from high smoothness, the method of bonding the other slippery film to a film board | substrate, and the method of providing a slidable layer in a film board | substrate are mentioned. When bonding another film to a film substrate, 2nd from a viewpoint of suppressing the problem (failure of orientation of an liquid crystal, an optical defect, etc.) resulting from transfer, such as a contact bonding layer, to a 1st main surface (surface to which a liquid crystalline composition is apply | coated). It is preferable to bond together to a main surface (surface on the opposite side to the coating surface of a liquid crystalline composition). However, in the roll-to-roll process, the adhesive or the like adhered to the second main surface at the time of winding up of the film substrate may adhere to the first main surface, which may cause orientation defects or optical defects.

Therefore, it is preferable to improve slipperiness by providing a slidable layer on at least one surface of a film substrate. As an easily slid layer, what contained the microfiller whose average particle diameter is 100 nm or less in binders, such as polyester and polyurethane, is mentioned, for example.

After bonding the orientation liquid crystal film 1 with the film 4, when peeling from the film substrate 8 (refer FIG. 2B and FIG. 2C), peelability is maintained and at the time of peeling from the film substrate 8 It is preferable that the film board | substrate 8 does not have an easily slid layer in the surface which apply | coats a liquid crystalline composition from a viewpoint of suppressing problems, such as transfer of the easily slid layer to the orientation liquid crystal film 1, and the like. That is, it is preferable to use the film substrate which has an easily slid layer on a 2nd main surface, and does not have an easily slid layer on a 1st main surface.

<Formation of Oriented Liquid Crystal Film on Film Substrate>

An orientation liquid crystal film is obtained by apply | coating a liquid crystalline composition on a film board | substrate, orientating a liquid crystalline compound as a liquid crystal state by heating, cooling, fixing an orientation, and superposing | polymerizing or crosslinking a photopolymerizable liquid crystal compound by light irradiation. Lose.

The method of apply | coating a liquid crystalline composition on a film substrate is not specifically limited, A spin coat, a die coat, a kiss roll coat, a gravure coat, a reverse coat, a spray coat, a meyer bar coat, a knife roll coat, an air knife coat, etc. are employ | adopted. can do. After apply | coating a solution, a liquid crystalline composition layer is formed on a film substrate by removing a solvent. It is preferable to adjust application | coating thickness so that thickness (thickness of the orientation liquid crystal film) of the liquid crystalline composition layer after drying a solvent may be about 0.5-7 micrometers.

The liquid crystal compound is aligned by heating the liquid crystal composition layer formed on the film substrate to form a liquid crystal phase. Although heating temperature is not specifically limited, Usually, it is about 40-200 degreeC. When the heating temperature is excessively low, the transition to the liquid crystal phase tends to be insufficient, and when the heating temperature is excessively high, the alignment defect tends to increase. Therefore, 45-100 degreeC is preferable, as for heating temperature, 50-95 degreeC is more preferable, and 55-90 degreeC is further more preferable. What is necessary is just to adjust heating time so that transition to a liquid crystal phase may become enough, and it is about 30 second-30 minutes normally.

When the stretched film substrate which does not provide the oriented film is used, there exists a tendency for the homogeneous orientation regulation force resulting from the molecular orientation of a film substrate to become strong with the raise of heating temperature. When producing a homeotropic oriented liquid crystal film by apply | coating and using a liquid crystalline composition on the stretched film board | substrate with which the oriented film is not provided, it is preferable to perform heating at low temperature within the temperature range which a liquid crystal polymer transitions to a liquid crystal phase. Do. As for the heating temperature T (degreeC) in orientation, 100-3.5x10 <^{3> (} DELTA) n or less is preferable. Δn is the in-plane birefringence of the stretched film substrate. The heating temperature is T, 100 - 4 × 10 ³ Δn or less are more preferred, and, 100 - 4.5 × 10 ³ Δn is less more preferred. Further, the heating temperature T, 100 - 0.1R _0, and preferably less than, 100 - 0.12R ₀ and less are more preferred, 100 - 0.13R ₀ is more preferably less. R ₀ is an in-plane retardation of the stretched film substrate.

As mentioned above, even when the board | substrate which does not have an orientation film is used by using the stretched film board | substrate with high smoothness and adjusting the heating temperature T at the time of orienting a liquid crystal, the orientation defect of a homeotropic oriented liquid crystal film is suppressed. can do. Homeotropic alignment liquid crystal film is light leakage (orientation defect) is more preferably 1cm ² is 1 or less is preferable, and more preferably 0.7 or less, 0.5 or less per dog is observed under a polarizing microscope. The number of orientation defects is calculated | required as the average value which observed 10 places in a film surface.

After heating, the orientation is fixed by cooling to a temperature below the glass transition temperature. The cooling method is not specifically limited, For example, what is necessary is just to take out at room temperature in a heating atmosphere. Forced cooling, such as air cooling and water cooling, may be performed.

By irradiating light to the liquid crystal composition layer having a fixed orientation and polymerizing or crosslinking the photopolymerizable liquid crystal compound, the orientation of the photopolymerizable liquid crystal compound is fixed, and the durability of the alignment liquid crystal film is improved. As light to irradiate, what is necessary is just to select the light of the wavelength which a photoinitiator has a sensitivity, and an ultraviolet-ray is generally used. As the ultraviolet light source, a low pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a metal halide lamp, a xenon lamp, an LED, a black light, a chemical lamp and the like are used. In order to promote the photopolymerization reaction, light irradiation is preferably performed under an inert gas atmosphere such as nitrogen gas.

When the photopolymerizable liquid crystal compound contains a compound (for example, a polymer) which does not have photopolymerizable property in addition to the photopolymerizable liquid crystal compound, the photopolymerizable compound undergoes curing by light irradiation, while the photopolymerization Compounds that do not have sex do not react. When the compound which does not have photopolymerizable property is unevenly distributed in the coating layer of a liquid crystalline composition, a local difference arises in the hardness of an orientation liquid crystal film with progress of a photocuring reaction.

For example, when the liquid crystal composition containing a photopolymerizable liquid crystal compound and a side chain type liquid crystal polymer is apply | coated on the film substrate 8, in a coating layer, a side chain type liquid crystal polymer will be near the interface with the film substrate 8, and the air interface vicinity. Tends to be omnipresent. As described above, when the photocuring is performed in a state in which the polymer is unevenly located near the interface, the hardness of the central portion (region where the concentration of the photopolymerizable compound is high) in the thickness direction of the liquid crystal layer increases as the photocuring progresses. (The area | region where the density | concentration of a photopolymerizable compound is small and a polymer concentration is high), since the change of hardness is small, the hardness difference in the thickness direction (depth direction) becomes large. Accordingly, there is a tendency that the ratio F ₃₀ / F ₁₅ of the lateral load F ₃₀ at a depth 15㎚ lateral load F ₁₅ and depth 30㎚ in from the surface (interface) is enhanced.

To the F ₃₀ / F ₁₅ to below 2.2, by adjusting the amount of irradiation light at the time of photo-curing it is preferred to suppress excessive progress of photo-curing. The greater the amount of irradiation light at the time of photo-curing, there is a tendency, because the photo-curing of a light-polymerizable liquid crystal compound in progress is F ₃₀ / F ₁₅ is enhanced.

Accumulated irradiation light amount at the time of photocuring is more preferably 370mJ / cm ² or less is preferable, and less than 350mJ / cm ^2. On the other hand, when the amount of light irradiation is excessively small, the curing of the photopolymerizable compound is insufficient, and the hardness and heat durability of the alignment liquid crystal film tend to be lowered. Accordingly, the accumulated amount of light irradiated at the time of photo-curing is more preferably 100mJ / cm ² or more are preferred, 130mJ / cm ² or more is more preferable, 150mJ / cm ² or more. The integrated irradiation light quantity at the time of photocuring of an orientation liquid crystal film is the integrated light quantity of UVA (wavelength 320-390 nm) measured using the integrated photometer.

As described above, F ₃₀ / F ₁₅ of the liquid crystal alignment film is preferably from 1 to 2.2. F ₃₀ / F ₁₅ is more preferably from 1.1 to 2.1 is more preferred, and from 1.2 to 2. F ₃₀ / F ₁₅ that is the above-mentioned range, and then using a pressure-sensitive adhesive combined Mole a liquid crystal film aligned in the image display cell, when performing the rework, it is difficult to cohesive failure of the aligned liquid crystal film occurs, to suppress the rework defective Can be. F ₃₀ / F ₁₅ is 1.3 or more, and may be more than 1.5 or more than 1.4. F ₃₀ / F ₁₅ may be a less than 1.8 or less than 1.9.

From the viewpoint of giving sufficient hardness to the alignment liquid crystal film, the horizontal load F ₁₅ at a depth of 15 nm from the surface is preferably 1 µN or more, more preferably 2 µN or more, and still more preferably 2.5 µN or more. F ₁₅ or more or 3.5 μN or more may be used. On the other hand, F from the viewpoint of maintaining the ₃₀ / F ₁₅ to an appropriate range, F is ₁₅ or less 20μN preferred, and 15μN less than, more preferably not more than 10 μN. F ₁₅ or less, 6 or less, 5 or less, or 4.5 or less may be sufficient as F ₁₅ .

When the amount of light irradiation at the time of photocuring is large and hardening of a photopolymerizable compound advances, there exists a tendency for the horizontal load of an orientation liquid crystal film to become large. On the other hand, in the case where the polymer is unevenly distributed near the interface, even if the curing of the photopolymerizable compound proceeds, the change in the horizontal load near the interface is small. Therefore, ₁₅ F is larger the influence of the properties of the polymer contained in the liquid crystal composition. Thus oriented, by selecting the structure and the molecular weight of the polymer contained in the liquid crystal composition can be set to F ₁₅ of the liquid crystal film in the above range.

Horizontal load in 30㎚ depth from the surface of the aligned liquid crystal film F ₃₀ is 1.5μN above are preferred, more than 2.5μN more preferable, and at least 3μN more preferred. F ₃₀ may be a more than 3.5μN, 4μN over, or at least more than 5μN 4.5μN. On the other hand, from the viewpoint of maintaining F ₃₀ / F ₁₅ in an appropriate range, ₄₀ μN or less is preferable, 25 μN or less is more preferable, and 15 μN or less is more preferable. F ₃₀ may be a 10μN than, or less than 9μN 8μN below.

Even when the polymer is ubiquitous near the interface, the concentration of the photopolymerizable compound is high and the concentration of the polymer is low near the depth of 30 nm from the surface, so that F ₃₀ increases as the curing of the photopolymerizable compound proceeds. There is this. Therefore, it is possible to adjust the range of the F ₃₀ desired by adjusting the amount of irradiation light at the time of photo-curing.

[Use of Oriented Liquid Crystal Film]

An oriented liquid crystal film can be used as an optical film for displays for the purpose of viewing angle compensation, etc. The alignment liquid crystal film may be used in a state of being laminated with the film substrate, or may be used after being peeled from the film substrate. As shown in FIG. 2C, after the alignment liquid crystal film 1 is bonded with another film 4 via the adhesive bond layer 3, it is preferable to peel the film substrate 8 as shown in FIG. 2D. . By bonding together with the film 4 via the adhesive bond layer 3, the laminated optical film with which the orientation liquid crystal film was firmly adhere | attached on the film 4 is obtained.

The optical characteristic of an orientation liquid crystal film is not specifically limited. Positive homeotropic alignment liquid crystal film has positive in-plane retardation of approximately 0 (eg, 5 nm or less, preferably 3 nm or less), and thickness direction retardation is negative (having refractive index anisotropy of nz> nx = ny). Plate. Homeotropic alignment (nx-nz) and multiplying the thickness direction retardation R _t represented by the thickness of the liquid crystal film is, for example, -50 ~ -500㎚ degree.

[Optical Film with Adhesive]

When bonding the orientation liquid crystal film 1 with the image display cell 50, and forming an image display apparatus, it is preferable to use the optical film with an adhesive which laminated | stacked the adhesive layer 2 on the surface of the orientation liquid crystal film 1 previously. Do. The optical film with an adhesive may be equipped with the adhesive layer in any of the board | substrate surface 11 and the air surface 12 of the orientation liquid crystal film 1.

<Adhesive layer>

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 2 is not particularly limited and may be appropriately selected from acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine polymers, rubber polymers, and the like as base polymers. have. In particular, the adhesive which is excellent in transparency, such as an acrylic adhesive or a rubber adhesive, shows moderate wettability, cohesion, and adhesiveness, and is excellent in weather resistance, heat resistance, etc. is preferable. The thickness of an adhesive layer is suitably set according to the kind of to-be-adhered body, etc., and it is generally about 5-500 micrometers.

When providing an adhesive layer in the air plane 12 of the orientation liquid crystal film 1, it is an adhesive in the air plane 12 in the state (see FIG. 2A) in which the alignment liquid crystal film 1 was installed on the film substrate 8 What is necessary is to laminate | stack a layer. When providing an adhesive layer in the air surface 11 of the orientation liquid crystal film 1, the film substrate 8 is peeled from the orientation liquid crystal film 1, and the board | substrate surface 11 of the orientation liquid crystal film 1 is removed. After the exposure, the pressure-sensitive adhesive layer 2 may be laminated on the substrate surface 11.

Lamination of the pressure-sensitive adhesive layer 2 onto the alignment liquid crystal film 1 is performed by bonding the pressure-sensitive adhesive previously formed into a sheet shape on the surface of the alignment liquid crystal film 1, for example. After apply | coating an adhesive composition on the orientation liquid crystal film 1, you may form the adhesive layer 2 by performing solvent drying, bridge | crosslinking, photocuring, etc. In order to raise the adhesive force (transposition force) of the orientation liquid crystal film 1 and the adhesive layer 2, after forming surface treatments, such as a corona treatment and a plasma treatment, and an easily bonding layer on the surface of the orientation liquid crystal film 1, an adhesive layer You may laminate | stack (2).

Since the orientation liquid crystal film 1 has a small thickness, it is difficult to say that the alignment liquid crystal film 1 alone has sufficient handling properties. Therefore, when laminating | stacking the adhesive layer 2 on the board | substrate surface 11 of the orientation liquid crystal film 1, in the state in which the orientation liquid crystal film 1 was installed on the film substrate 8 (FIG. 2A), orientation After bonding the film 4 to the liquid crystal film 1 air plane 12 (FIG. 2B), it is preferable to peel off the film substrate 8 from the substrate surface 11 of the alignment liquid crystal film 1 (FIG. 2C). When the orientation liquid crystal film 1 and the other film 4 are laminated | stacked, compared with the case of the orientation liquid crystal film 1 alone, thickness is large and handling property improves.

<Separator>

It is preferable that the separator 9 adheres to the surface of the adhesive layer 2. The separator 9 protects the surface of the adhesive layer 2 until the optical film with an adhesive is bonded with the image display cell 50. As a constituent material of the separator, plastic films such as acrylic, polyolefin, cyclic polyolefin, and polyester are preferably used. The thickness of the separator is usually about 5 to 200 µm. It is preferable that the mold release process is given to the surface of a separator. As a mold release agent, a silicone type material, a fluorine type material, a long chain alkyl type material, a fatty acid amide type material, etc. are mentioned.

<Other film>

The film 4 bonded to the orientation liquid crystal film 1 is not specifically limited, The optically isotropic or optically anisotropic film generally used as an optical film can be used without a restriction | limiting in particular. The film 4 may be a single layer film or a laminate of a plurality of films.

As a specific example of the film 4, a retardation film, a polarizer, a polarizer protective film, etc. are mentioned. The film 4 may be a functional film such as a viewing angle expanding film, a viewing angle restriction (peeling prevention) film, a brightness enhancing film, or the like.

For example, in a liquid crystal display device, as an optical compensation film between an image display cell (liquid crystal cell) and a polarizer for the purpose of suitably converting the polarization state of the light radiate | emitted from a liquid crystal cell to the visual recognition side, and improving a viewing angle characteristic. Retardation plates may be arranged in some cases. In the organic EL display device, a quarter wave plate may be disposed between the cell and the polarizing plate in order to suppress external light from being reflected by the metal electrode layer and viewed like a mirror surface. Further, by disposing a quarter-wave plate on the viewing side of the polarizing plate and making the emitted light circularly polarized, an appropriate image display can be visually recognized even for a viewer equipped with polarized sunglasses.

The film 4 may be integrated with the alignment liquid crystal film 1 and may have a predetermined function. For example, the alignment liquid crystal film 1 is a homeotropic alignment film (positive C plate), and the film 4 is a polarizing plate (circular polarizing plate) having a quarter wave plate and a polarizer on the alignment liquid crystal film 1 side. In this case, the homeotropic alignment liquid crystal film and the quarter wave plate are laminated to form a circularly polarizing plate capable of shielding the reflected light against external light in a diagonal direction. Such a circular polarizing plate can be bonded to the surface of an organic EL cell, for example, and can be used.

<Adhesive>

It is preferable to bond together the orientation liquid crystal film 1 and the film 4 through the appropriate adhesive bond layer 3. The material is not particularly limited as long as the adhesive is optically transparent, and examples thereof include epoxy resins, silicone resins, acrylic resins, polyurethanes, polyamides, polyethers, and polyvinyl alcohols. The thickness of the adhesive bond layer 3 is about 0.01-20 micrometers, for example, and is set suitably according to the kind of to-be-adhered body, the material of an adhesive agent, etc. When using the curable adhesive which shows adhesiveness by the crosslinking reaction after application | coating, 0.01-5 micrometers is preferable and, as for the thickness of the adhesive bond layer 3, 0.03-3 micrometers is more preferable.

As an adhesive agent, various forms, such as an aqueous adhesive agent, a solvent adhesive agent, a hot melt adhesive system, and an active energy ray hardening-type adhesive agent, are used. Among these, an aqueous adhesive or an active energy ray hardening-type adhesive is preferable at the point which can make thickness of an adhesive bond layer small.

As an aqueous adhesive agent, what contains water-soluble or water-acidic polymers, such as vinyl polymer type, gelatin type, vinyl type, latex type, polyurethane type, isocyanate type, polyester type, epoxy type, etc. can be illustrated, for example. The adhesive bond layer which consists of such an aqueous adhesive agent is formed by apply | coating aqueous solution on a film and drying it. At the time of preparation of aqueous solution, a catalyst, such as a crosslinking agent, another additive, an acid, can be mix | blended as needed.

As a crosslinking agent mix | blended with an aqueous adhesive agent, it is boric acid or borax; Carboxylic acid compounds; Alkyl diamines; Isocyanates; Epoxy; Monoaldehydes; Dialdehydes; Amino-formaldehyde resins; And salts of divalent metals or trivalent metals and oxides thereof.

The active energy ray-curable adhesive is an adhesive capable of radical polymerization, cationic polymerization or anionic polymerization by irradiation of active energy rays such as electron beams or ultraviolet rays. Especially, since it can harden | cure at low energy, the radical photopolymerizable adhesive which starts radical polymerization by ultraviolet irradiation is preferable.

As a monomer of a radically polymerizable adhesive agent, the compound which has a (meth) acryloyl group, and the compound which has a vinyl group is mentioned. Especially, the compound which has a (meth) acryloyl group is preferable. As a compound which has a (meth) acryloyl group, Alkyl (meth) acrylates, such as C _1-20 linear alkyl (meth) acrylate, alicyclic alkyl (meth) acrylate, and polycyclic alkyl (meth) acrylate; Hydroxyl group-containing (meth) acrylates; Epoxy-group containing (meth) acrylates, such as glycidyl (meth) acrylate, etc. are mentioned. Radical polymerizable adhesives include hydroxyethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, (meth) acrylamide. Nitrogen containing monomers, such as an amide and a (meth) acryloyl morpholine, may be included. The radically polymerizable adhesive is a crosslinking component, such as tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate And polyfunctional monomers, such as EO modified diglycerol tetraacrylate.

It is preferable that photocurable adhesive agents, such as an optical radically polymerizable adhesive agent, contain a photoinitiator. What is necessary is just to select a photoinitiator suitably according to reaction species. For example, it is preferable to mix | blend an optical radical generating agent which produces | generates a radical by light irradiation as a photoinitiator to a radically polymerizable adhesive agent. Specific examples of the optical radical generator will be described later. Content of an optical radical generating agent is about 0.1-10 weight part normally with respect to 100 weight part of monomers, Preferably it is 0.5-3 weight part. In addition, when using a radically polymerizable adhesive agent as an electron beam curing type, a photoinitiator is not necessary in particular. The photosensitizer represented by a carbonyl compound etc. can also be added to a radically polymerizable adhesive agent as needed. A photosensitizer is used in order to raise the hardening rate or sensitivity by an electron beam. The usage-amount of a photosensitizer is about 0.001-10 weight part normally, Preferably it is 0.01-3 weight part with respect to 100 weight part of monomers.

The adhesive agent may contain the additive suitably as needed. Examples of the additive include a coupling agent such as a silane coupling agent and a titanium coupling agent, an adhesion promoter such as ethylene oxide, an ultraviolet absorber, a deterioration inhibitor, a dye, a processing aid, an ion trap agent, an antioxidant, a tackifier, a filler, a plasticizer, and a leveling agent. , Foam inhibitors, antistatic agents, heat stabilizers, hydrolysis stabilizers and the like.

<Photocuring of adhesive>

As mentioned above, the orientation liquid crystal film 1 can adjust the ratio of the horizontal load of the depth direction by adjusting the light irradiation amount at the time of photocuring the polymer of a photopolymerizable liquid crystal compound. When unreacted photoinitiator remains in the orientation liquid crystal film, superposition | polymerization (photocuring) of the photopolymerizable liquid crystal compound of the orientation liquid crystal film 1 may advance by the light irradiation at the time of hardening an adhesive agent.

When the photocuring of the orientation liquid crystal film advances at the time of photocuring of the adhesive bond layer 3, the hardness of the place where the depth is large becomes relatively high compared with the vicinity of surface layer (interface), and F ₃₀ / F ₁₅ may increase. In order to keep the F ₃₀ / F ₁₅ of the liquid crystal film to a suitable range, it is preferable to suppress the photo-curing of a liquid crystal alignment film when the light irradiation for curing of the adhesive.

In order to suppress hardening of the orientation liquid crystal film at the time of adhesive photocuring, light of longer wavelength may be irradiated than irradiation light for photocuring of a liquid crystalline composition, for example at the time of photocuring of an adhesive agent. When irradiating light of a long wavelength relatively at the time of photocuring of an adhesive agent, since the photocuring of the oriented liquid crystal film which has a sensitivity to light of a short wavelength hardly advances, progress of the undesired photocuring of an oriented liquid crystal film can be suppressed. have.

The wavelength of light to be irradiated at the time of photocuring mainly depends on the wavelength of the sensitivity of the photoinitiator contained in a composition. Therefore, it is preferable that the photoinitiator contained in a photocurable adhesive agent has a sensitivity to long wavelength rather than the photoinitiator contained in a liquid crystalline composition. More specifically, it is preferable that the photoinitiator contained in a photocurable adhesive agent has a sensitivity to long wavelength rather than wavelength 380 nm, and it is more preferable to have a sensitivity to long wavelength rather than 400 nm. It is preferable to use the photoinitiator whose light absorption coefficient in wavelength 405nm is 1 * 10 <^2> [mLg <^-1> cm <^-1> ] or more as a photocurable adhesive agent. The photoinitiator which has long wavelength photosensitivity may have a sensitivity with respect to the light of wavelength 400nm or less.

As a specific example of the photoinitiator which has a light sensitivity of wavelength 400nm or more, 2,4,6-trimethylbenzoyl diphenylphosphine oxide ("Lucirin TPO" by BASF) and 2,4,6-trimethylbenzoyl phenylethoxyphosphine oxide Acylphosphine oxides such as (Lucirin TPO-L manufactured by BASF); Amino ketones such as 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (" Irugacua 369 " manufactured by BASF); Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide ("Irugacua 819" manufactured by BASF), bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide ( Bisacyl phosphine oxides, such as BASF made "CGI403"), etc. are mentioned.

As a photoinitiator which has a long wavelength photosensitivity, you may use the photoradical generator which produces | generates a radical by hydrogen extraction. As a hydrogen draw type | mold photoinitiator, a thioxanthone type photoinitiator, a benzophenone type photoinitiator, etc. are mentioned. Since the radical generation efficiency by long wavelength light is higher than the wavelength of 380 nm, and absorption of visible light is small, a thioxanthone type photoinitiator (photo radical generator) is preferable. Examples of thioxanthone-based radical photopolymerization initiators include thioxanthone, dimethyl thioxanthone, diethyl thioxanthone, isopropyl thioxanthone, and chloro thioxanthone.

By using a photopolymerization initiator having a long wavelength light sensitivity and a photopolymerization initiator having a small long wavelength sensitivity in combination, a radical can be generated in a photopolymerization initiator having a long wavelength light sensitivity by acting as a sensitizer. Moreover, you may use together the sensitizer for radical photopolymerization, such as a thiopyryllium salt, merocyanine, quinoline, stilquinoline, aryl ketones, aromatic ketones, a ketocoumarin derivative, an anthracene derivative, and a photoinitiator.

As a light source of the long wavelength light used for the photocuring of an adhesive agent, a gallium encapsulated metal halide lamp, an LED light source which emits wavelength range 380-440 nm, etc. are preferable. Alternatively, using a light source including ultraviolet light and visible light such as a low pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a metal halide lamp, and a xenon lamp, a band pass filter and a long pass filter may be used. A short wavelength ultraviolet-ray may be shielded using a wavelength selective filter. Light from a gallium-enclosed metal halide lamp or an LED light source may be irradiated through a wavelength filter to perform photocuring of the adhesive.

The amount of integrated irradiation light at the time of adhesive photocuring is about 100-2000mJ / cm <^2> , for example, What is necessary is just to adjust suitably according to the composition, thickness, etc. of a photocurable adhesive. When performing photocuring of an adhesive agent by irradiating light of a long wavelength rather than at the time of photocuring of a liquid crystalline composition, it is preferable that the accumulated irradiation light quantity of UVV (wavelength 395-445 nm ultraviolet-visible light) is the said range.

In order to suppress the photocuring of the orientation liquid crystal film from advancing at the time of photocuring of an adhesive agent, the photoinitiator contained in a liquid crystalline composition has photosensitivity to short wavelength rather than the photoinitiator contained in a photocurable adhesive agent, and has the photosensitivity of long wavelength light. It is preferable not to show. As a photoinitiator which does not have long wavelength photosensitivity, it is preferable that the extinction coefficient in wavelength 405nm is less than 1x10 <^2> [mLg <^-1> cm <^-1> ]. It is preferable that the photoinitiator contained in a liquid crystalline composition has an extinction coefficient in wavelength 405nm less than 1x10 <^2> [mLg <^-1> cm <^-1> ]. Moreover, it is preferable that the photoinitiator contained in a liquid crystalline composition has a light absorption coefficient in 302 nm of 1x10 <^2> [mLg <^-1> cm <^-1> ] or more.

As a photoinitiator which does not have long-wavelength light sensitivity, a benzoin ether type photoinitiator, an acetophenone type photoinitiator, the (alpha)-ketol type | system | group photoinitiator, a photoactive oxime type | system | group photoinitiator, a benzoin type | system | group photoinitiator, and a benzyl-type photopolymerization An initiator, a benzophenone system photoinitiator, a ketal system photoinitiator, an acylphosphine oxide system photoinitiator, a titanocene system photoinitiator, etc. are mentioned.

As a specific example of the photoinitiator which does not show the light sensitivity of long wavelength light, benzophenone, 2,4,6-trimethyl benzophenone, 4-methylbenzo phenone, hydroxycyclohexyl phenyl ketone ("Irugacua 184" by BASF), 2 , 2-dimethoxy-1,2-diphenylethan-1-one ("Irugacua 651" manufactured by BASF), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (manufactured by BASF " Irgacua 1173 "), 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (" Irugacua 2959 "manufactured by BASF) , 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one ("Irugacua 907" manufactured by BASF), 2- (dimethylamino) -1- (4-morpholin Nophenyl) -2-benzyl-1-butanone ("Irugacua 369" manufactured by BASF), 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl)- Benzyl] phenyl} -2-methyl-propan-1-one ("Irugacua 127" manufactured by BASF), benzyl methyl ketal ("Essacu KB1" manufactured by DKSH), 2-hydroxy-2-methyl- [4- (1-methylvinyl) phenyl] propanol oligo And the like (manufactured DKSH "Asa Cure KIP150").

[Image display device]

The image display apparatus can be formed by bonding the orientation liquid crystal film 1 to the surface of image display cells 50, such as a liquid crystal cell and an organic electroluminescent cell, via the adhesive layer 2. FIG. As mentioned above, in formation of an image display apparatus, it is preferable to use the optical film with an adhesive which provided the adhesive layer 2 on the surface of the orientation liquid crystal film 1 previously. The optical film with an adhesive is provided with the adhesive layer 2 for bonding with an image display cell on one side of the orientation liquid crystal film 1, and the other film 4 is provided through the adhesive layer 3 on the other side. It may be bonded together.

When the bonding failure occurs after bonding the optical film with pressure-sensitive adhesive to the image display cell, or when a defect due to a defect of the optical film is detected, an operation (rework) of peeling the optical film from the image display cell is performed. . If a portion having a small strength (hardness) locally exists in the thickness direction of the film, cohesive failure may occur at a portion having a small strength locally due to peeling force at the time of rework, which may cause a rework failure. . In this invention, since the hardness distribution of the thickness direction of an orientation liquid crystal film exists in a predetermined range, the cohesive failure of an orientation liquid crystal film hardly arises and it is excellent in rework property. Therefore, by using the orientation liquid crystal film of this invention, while improving the productive efficiency of an image display apparatus, the yield improvement of a product can also be anticipated.

EXAMPLE

Next, although an example of preparation of a homeotropic alignment liquid crystal film is given and this invention is demonstrated in detail, this invention is not limited to the following example.

[Production of Liquid Crystal Composition]

80 parts by weight of a side chain type liquid crystal polymer having a weight average molecular weight of 5000 of the following formula (n = 0.35 and represented by a block polymer for convenience) and a polymerizable liquid crystal compound (BAPaicolor LC242 'manufactured by BASF) Part and 5 parts by weight of 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one (BARU, "Irugacua 907") as a photopolymerization initiator, 400 parts by weight of cyclopentanone It melt | dissolved in and prepared the liquid crystalline composition.

[Production of alignment liquid crystal film]

As a film base material, the biaxially-stretched norbornene-type film which has a slid layer on one side (Japan Zeon "Zenoa film", thickness: 33 micrometers, in-plane retardation: 135 nm, the arithmetic mean roughness of the slid layer non-forming surface: 1.0 Nm) was used. The liquid crystal composition was applied to a non-molding layer-forming surface of the film base material by a bar coater so that the thickness after drying was 1 µm, and the liquid crystal was aligned by heating at 80 ° C. for 2 minutes. Then, it cooled to room temperature and fixed orientation, the ultraviolet-ray (UVA: 320-390 nm) of the accumulated light quantity shown in Table 1 was irradiated under nitrogen atmosphere, the liquid crystal monomer was photocured, and the orientation liquid crystal film was produced. For the irradiation of ultraviolet rays, the cumulative light amount of UVA was measured by a UV illuminance measurement system (UV power Puck II manufactured by Herus) using an electrodeless UV lamp system (H valve of 'LIGHT HAMMER 10' manufactured by Herus.

[Production of Optical Film with Adhesive]

62 parts by weight of hydroxyethyl acrylamide ('HEAA' manufactured by Kojin), 25 parts by weight of acryloyl morpholine ('ACMO' manufactured by Kojin), PEG400 #diacrylate (light acrylate 9EG manufactured by Koeisha Kagaku) -A ') 7 parts by weight, and 3 parts by weight of 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one (' Irugacua 907 'manufactured by BASF) as a photopolymerization initiator And 2,4-diethyl thioxanthone ("Kayakyua DETX-S" manufactured by Nippon Kayaku Co., Ltd.) were mixed to prepare a photocurable adhesive composition. After apply | coating the photocurable adhesive composition to 1 micrometer thickness on the surface of the extending | stretching retardation film of thickness 48micrometer, and bonding the said orientation liquid crystal film on the application layer of an adhesive agent, the ultraviolet-visible ray (UVV) of accumulated light quantity 700mJ / cm <^2> . : 395-445 nm) was irradiated to harden an adhesive agent. For the irradiation of ultraviolet rays, short wavelength light was cut by a long pass filter having a cut-on wavelength of 380 nm using a V valve of an electrodeless UV lamp system ('LIGHT HAMMER 10' manufactured by Herus). The accumulated light quantity of UVV was measured by the UV illuminance measuring system ('UV Power Puck II' by Heraeus).

The film base material was peeled from the orientation liquid crystal film, the easily bonding layer of thickness about 30 nm was formed on the surface of the orientation liquid crystal film, the acrylic adhesive sheet of thickness 15micrometer was bonded together on it, and the optical film with an adhesive was obtained.

[evaluation]

<Horizontal load>

The alignment liquid crystal film (which was placed on the film substrate) before bonding the stretched film was fixed on the stage of the nanoindentation system ("TI950 TriboIndenter" manufactured by Hysitron). A load was applied using a diamond indenter (triangle radius of curvature: 0.1 μm) of the bark pitch (triangular weight) type, pushed to a depth of 15 nm, and the stage was moved horizontally by 10 μm (moving speed of 0.5 μm / sec), It was the maximum value of load in the range of the horizontal movement by the horizontal distance 0.2㎛ load F _15. Changing the indentation depth of the indenter into 30㎚, which was equal to measures the horizontal force F _30.

<The anchoring force>

The optical film with an adhesive was cut into width 50mm and length 200mm, and the surface by the side of an extending | stretching retardation film was bonded to the glass plate with double-sided tape. The ITO film cut | disconnected to width 25mm and length 200mm was bonded together on the acryl-type adhesive sheet of the optical film with an adhesive, and what was left to stand at room temperature for 20 minutes was used as the measurement sample. Using a tensile compression tester (TCN-1kNB manufactured by Minnebea), the peeling force (peeling force at the interface between the alignment liquid crystal film and the acrylic pressure-sensitive adhesive layer) determined by a 180 ° peeling test at a tensile speed of 300 mm / min is anchored. Force.

<Reworkability>

The pressure sensitive adhesive polarizing plate was cut out into a rectangle of 150 mm × 150 mm, and the optical film with pressure sensitive adhesive was bonded to an alkali free glass plate manufactured by Corning using a hand roller. It peeled from the glass plate parallel to the long side direction at the short side of a film, and confirmed the presence or absence of adhesives, etc. to the surface of a glass plate. This rework test was conducted 10 times for each sample, and the reworkability was determined based on the following criteria.

(Circle): For all 10 samples, there was no residue to a glass surface, and it reworked favorably.

(Triangle | delta): The residue (rework retardation) to the glass surface was seen by 1-3 samples.

X: The residue (rework retardation) to the glass surface was seen in the sample of 4 or more sheets.

The accumulated light amount and evaluation result at the time of photocuring of the orientation liquid crystal film of each experiment example are shown in Table 1, and the graph which plotted the accumulated light quantity and the horizontal load of the orientation liquid crystal film is shown in FIG. Moreover, the cross-sectional image by the transmission electron microscope (TEM) of the optical film with an adhesive produced using the orientation liquid crystal film of sample 3 (accumulated light amount 250mJ / cm <^2> ) is shown in FIG.

TABLE 1

In Sample 1 having an integrated light quantity of 50 mJ / cm ² , F ₃₀ / F ₁₅ of the alignment liquid crystal film was small, and a rework failure occurred. On the other hand, the cumulative dose 450mJ / cm ² or more samples 5 to 8, showed a tendency of F ₃₀ / F of the liquid crystal film ₁₅ is large, the anchoring force decreases with the increase of F ₃₀ / F _15, Rework poor It was happening.

As shown in FIG. 4, the horizontal load F ₃₀ at a depth of 30 nm tended to increase as the amount of accumulated light at the time of photocuring of the alignment liquid crystal film increases. The horizontal load F ₁₅ at a depth of 15 nm gradually increased with the increase of the accumulated light amount, but the increase amount was small compared to F ₃₀ . Therefore, it can be seen, there is a tendency that the F ₃₀ / F ₁₅ increases with an increase in accumulated light quantity.

As shown on the TEM of FIG. 5, the alignment liquid crystal film is a region in which contrast is different in the interface (substrate surface at the time of orientation liquid crystal film production) and the interface (air surface at the time of orientation liquid crystal film production) on the adhesive layer side. This looked. Composition analysis in the thickness direction of the alignment liquid crystal film was performed by time-of-flight secondary ion mass spectrometry (TOF-SIMS), where the concentration of the side chain type liquid crystal polymer was high in the vicinity of the interface, and the concentration of the polymer of the liquid crystal monomer was relatively high. As low as (data not shown).

As a result, F ₁₅ hardly changed even when irradiated with light because the polymer concentration was high in the vicinity of the interface (a region of about 15 nm in depth) of the alignment liquid crystal film, whereas light was irradiated because the monomer concentration was high in the region away from the interface. It is thought that F ₃₀ will increase with the progress of polymerization by. When F ₃₀ / F ₁₅ is small (e.g., less than 1) like Sample 1, photocuring is insufficient, and cohesive failure of the alignment liquid crystal film occurs during rework because the total strength of the alignment liquid crystal film is insufficient. It seems to be the cause of the rework failure. On the other hand, if the photo-curing proceeds excessively, F ₃₀ / F ₁₅ is increased, the orientation and the hardness difference between the center and the surface vicinity and the thickness of the liquid crystal film direction significantly, relative to the cohesive failure of the hardness is low interfacial vicinity It is thought that the rework failure occurred due to the easy occurrence.

On the other hand, F ₃₀ / F ₁₅ is in the sample 2-4, which is within a predetermined range, along with which the hardness of the liquid crystal orientation film, since a liquid crystal monomer is sufficiently cured to secure, localized force is small, the hardness distribution in the thickness direction, It is thought that the cohesive failure due to the concentration of is hardly generated and exhibits good reworkability.

1: alignment liquid crystal film
11: substrate surface
12: air plane
2: adhesive layer
3: adhesive layer
4: film
8: film substrate
9: separator
50: image display cell

Claims (15)

An alignment liquid crystal film composed of a liquid crystal layer in which liquid crystal molecules are aligned in a predetermined direction,
Two or more compounds, at least one of which is a polymer of a photopolymerizable liquid crystal compound,
The horizontal load at a depth of 30 nm from the surface is 1 to 2.2 times the maximum horizontal load at a depth of 15 nm from the surface,
Oriented Liquid Crystal Film. The method of claim 1,
A polymer containing a side chain type liquid crystal polymer and a photopolymerizable liquid crystal compound as the at least two kinds of compounds,
Oriented Liquid Crystal Film. The method of claim 2,
The side chain type liquid crystal polymer has a monomer unit containing a liquid crystalline fragment side chain and a monomer unit containing a non-liquid crystalline fragment side chain,
Oriented Liquid Crystal Film. The liquid crystal molecule is homeotropically oriented according to any one of claims 1 to 3,
Oriented Liquid Crystal Film. The alignment liquid crystal film of any one of Claims 1-3; And an adhesive layer provided on the first main surface of the alignment liquid crystal film,
Optical film with an adhesive. The method of claim 5,
Further provided with the other film bonded together on the 2nd main surface of the said orientation liquid crystal film via the adhesive layer,
Optical film with an adhesive. The image display apparatus by which the orientation liquid crystal film of any one of Claims 1-3 is bonded to the surface of an image display cell via an adhesive layer. As a manufacturing method of the orientation liquid crystal film which consists of a liquid crystal layer in which liquid crystal molecules were orientated in the predetermined direction,
An application step of applying a liquid crystalline composition containing a liquid crystalline compound on the first main surface of the film substrate having the first main surface and the second main surface;
A liquid crystal alignment step of heating the liquid crystal composition to orientate liquid crystal molecules in a predetermined direction; And
It has a photopolymerization process which superposes | polymerizes or crosslinks the said liquid crystalline compound by light irradiation,
The said liquid crystalline composition contains 2 or more types of compounds, At least 1 type is a photopolymerizable liquid crystal compound,
Cumulative irradiation light quantity in the said photopolymerization process is 100-370mJ / cm <^2> ,
The manufacturing method of an orientation liquid crystal film. The method of claim 8,
After the photopolymerization step, the maximum horizontal load at a depth of 30 nm from the surface of the alignment liquid crystal film is 1 to 2.2 times the maximum horizontal load at a depth of 15 nm from the surface,
The manufacturing method of an orientation liquid crystal film. The method according to claim 8 or 9,
As said 2 or more types of compound, A side chain type liquid crystal polymer and a photopolymerizable liquid crystal compound are included,
The manufacturing method of an orientation liquid crystal film. The method of claim 10,
The side chain type liquid crystal polymer has a monomer unit containing a liquid crystalline fragment side chain and a monomer unit containing a non-liquid crystalline fragment side chain,
The manufacturing method of an orientation liquid crystal film. The method according to claim 8 or 9,
The alignment film is not provided on the first main surface of the film substrate,
The manufacturing method of an orientation liquid crystal film. The method of claim 12,
The said film substrate is a stretched film which has in-plane retardation of 10-500 nm,
The manufacturing method of an orientation liquid crystal film. An alignment liquid crystal film comprising a liquid crystal layer in which liquid crystal molecules are aligned in a predetermined direction, an adhesive layer provided on a first main surface of the alignment liquid crystal film, and another film bonded through an adhesive layer on a second main surface of the alignment liquid crystal film. As a method of manufacturing the optical film with an adhesive,
An alignment liquid crystal film is provided on a film substrate by the method of Claim 8 or 9, and the laminated body which the 1st main surface of a film substrate and the 1st main surface of an orientation liquid crystal film contact | connects is formed,
Another film is bonded together through the adhesive bond layer on the 2nd main surface of the said orientation liquid crystal film,
The film substrate is peeled off from the alignment liquid crystal film
In which an adhesive layer is laminated | stacked on the 2nd main surface of the said orientation liquid crystal film,
The manufacturing method of the optical film with an adhesive. The method of claim 14,
The adhesive layer is a photocurable adhesive,
The light irradiated for curing the adhesive is light having a longer wavelength than the light irradiated for curing the polymerizable liquid crystal compound in the photopolymerization step when forming the alignment liquid crystal film,
The manufacturing method of the optical film with an adhesive.

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