WO2018235667A1 - Method for producing retardation substrate and method for producing liquid crystal display device - Google Patents

Abstract

The present invention provides a method for producing a retardation substrate, which is capable of producing a retardation substrate wherein the alignment properties of a reactive mesogen that constitutes a retardation film are improved. The present invention is a method for producing a retardation substrate wherein an alignment film and a retardation film are laminated on a substrate. This method for producing a retardation substrate comprises: a step for subjecting the alignment film to an alignment treatment; a step for forming an uncured film containing a reactive mesogen on the alignment film; and a step for forming the retardation film by irradiating the uncured film with polarized ultraviolet light so as to cause the reactive mesogen to undergo a curing reaction.

Description

Method of manufacturing retardation substrate, and method of manufacturing liquid crystal display device

The present invention relates to a method of manufacturing a retardation substrate and a method of manufacturing a liquid crystal display. More specifically, the present invention relates to a method of manufacturing a retardation substrate using a reactive mesogen, and a method of manufacturing a liquid crystal display device using the above-described method of manufacturing a retardation substrate.

A liquid crystal display device is a display device that uses a liquid crystal composition for display, and a typical display method is that light from a backlight is applied to a liquid crystal display panel in which the liquid crystal composition is sealed between a pair of substrates. The amount of light transmitted through the liquid crystal display panel is controlled by applying light to the liquid crystal composition to change the alignment of the liquid crystal molecules. Such liquid crystal display devices are characterized by their thinness, lightness, and low power consumption, and thus are used in electronic devices such as televisions, smartphones, tablet terminals, and car navigation systems. In such a liquid crystal display device, a retardation film may be used for the purpose of prevention of reflection of external light, compensation of color tone, compensation of viewing angle, and the like.

When the conventional liquid crystal display device is used in a bright place such as outdoors, the contrast may be reduced due to the influence of external light reflected by the inside and the surface of the liquid crystal display device, and the display quality may be deteriorated. On the other hand, by attaching a retardation film to the viewing surface side of the liquid crystal cell, the reflectance of external light can be reduced, and the visibility in the outdoors can be improved. On the other hand, in order to promote thinning of the liquid crystal display device and reduction of the number of members, instead of attaching a retardation film to a liquid crystal cell, a retardation layer (also referred to as "in-cell retardation layer") is provided in the liquid crystal cell. Was desired. As the in-cell retardation layer, one in which a retardation film composed of reactive mesogens is laminated on an alignment film is used.

As a prior art document regarding the phase difference film comprised by the reactive mesogen, patent document 1 is mentioned, for example. Patent Document 1 discloses a compound having a benzoxazinone ring and an aromatic ring directly linked to the benzoxazinone ring and having a mesogen nucleus substituted with a substituent having a polymerizable functional group. There is.

International Publication No. 2012/124719

In recent years, research and development have been advanced for in-cell retardation layers, but according to the study of the present inventor, in order for the liquid crystal display device to display high contrast, alignment of reactive mesogens constituting the retardation film It has been found desirable to further improve the sex.

The present invention has been made in view of the above-mentioned present situation, and provides a method for producing a retardation substrate capable of producing a retardation substrate in which the orientation of reactive mesogens constituting the retardation film is improved, and the retardation substrate An object of the present invention is to provide a method of manufacturing a liquid crystal display device using the manufacturing method.

As a result of various investigations on the method of improving the orientation of the reactive mesogen constituting the retardation film, the present inventors have improved the orientation by using polarized ultraviolet light as light used for curing reaction of the reactive mesogen. I found that I could do it. In addition, it was also found out that the orientation can be more effectively improved if the irradiation direction of polarized ultraviolet light is a specific direction. The present inventors have arrived at the present invention in view of the fact that the above-mentioned problems can be solved by this.

That is, one aspect of the present invention is a method for producing a retardation substrate in which an alignment film and a retardation film are laminated on a base material, and the process of aligning the alignment film, and the reaction on the alignment film. A phase difference substrate comprising the steps of: forming an uncured film containing a mesogenic mesogen; and irradiating the uncured film with polarized ultraviolet light which causes the curing reaction of the reactive mesogen to form a retardation film. It is a manufacturing method.

Another aspect of the present invention is a method of manufacturing a liquid crystal display including a step of manufacturing a retardation substrate using the above-described method of manufacturing a retardation substrate.

According to the present invention, it is possible to manufacture a retardation substrate capable of manufacturing a retardation substrate in which the orientation of the reactive mesogen constituting the retardation film is improved, and a liquid crystal display using the above-described method of manufacturing a retardation substrate. A manufacturing method can be provided.

FIG. 2 is a schematic cross-sectional view showing the retardation substrate of Embodiment 1. It is a figure explaining the relationship between the irradiation azimuth (1stPUV) of the polarization ultraviolet at the time of formation of alignment film 12a, the irradiation azimuth of polarization ultraviolet (2ndPUV) at the time of phase contrast film 12b formation, and irradiation azimuth theta. FIG. 7 is a schematic cross-sectional view showing the liquid crystal display device of Embodiment 2. It is a figure explaining the relationship between the irradiation direction of the polarization | polarized-light ultraviolet-ray to the alignment film 12a, and the irradiation direction of the polarization | polarized-light ultraviolet-ray to the retardation film 12b about Example 1 ((theta) = 0 degree). It is a figure explaining the relationship between the irradiation direction of the polarization | polarized-light ultraviolet-ray to alignment film 12a, and the irradiation direction of the polarization | polarized-light ultraviolet-ray to retardation film 12b about Example 4 ((theta) = 45 degrees). It is a figure explaining the relationship between the irradiation direction of the polarization | polarized-light ultraviolet-ray to alignment film 12a, and the irradiation direction of the polarization | polarized-light ultraviolet-ray to phase difference film 12b about Example 7 ((theta) = 90 degrees). 7 is a graph showing the measurement results of the contrast of the retardation substrates produced in Examples 1 to 7. 21 is a graph showing the measurement results of the contrast of the retardation substrates produced in Examples 8 to 14. 21 is a graph showing the measurement results of the contrast of the retardation substrates produced in Examples 15 to 21.

Hereinafter, the present invention will be described in more detail with reference to the drawings, but the present invention is not limited to these embodiments. Further, the configurations of the respective embodiments may be appropriately combined or changed without departing from the scope of the present invention.

In the present specification, the term “retardation film (retardation layer)” means a film (layer) that imparts an in-plane retardation of at least 10 nm to light having a wavelength of at least 550 nm. By the way, light of wavelength 550 nm is light of wavelength with the highest human visibility. The in-plane retardation is defined by R = (ns−nf) × d. Here, ns represents the larger one of the principal refractive indices nx and ny in the in-plane direction of the retardation film, and nf is the smaller one of the principal refractive indices nx and ny in the in-plane direction of the retardation film. Represents The principal refractive index refers to the value for light of wavelength 550 nm unless otherwise noted. The in-plane slow axis of the retardation film refers to the axis in the direction corresponding to ns, and the in-plane fast axis refers to the axis in the direction corresponding to nf. d represents the thickness of the retardation film. In the present specification, “retardation” means an in-plane retardation with respect to light having a wavelength of 550 nm unless otherwise noted.

In the present specification, the λ / 4 phase difference refers to an in-plane phase difference of at least 1⁄4 wavelength (strictly, 137.5 nm) for light of wavelength 550 nm, and a plane of 100 nm or more and 176 nm or less It may be an internal phase difference.

In the present specification, the “viewing surface side” means a side closer to the screen (display surface) of the liquid crystal display device, and the “back side” refers to the screen (display surface) of the liquid crystal display device. Mean the more distant side.

In the present specification, that two axes (directions) are orthogonal means that the angle (absolute value) between the two is in the range of 90 ± 3 °, preferably in the range of 90 ± 1 °, More preferably, it is in the range of 90 ± 0.5 °, and particularly preferably 90 ° (perfectly orthogonal).

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing the retardation substrate of the first embodiment. As shown in FIG. 1, the retardation substrate 10A of Embodiment 1 includes a base material 11 and an in-cell retardation layer 12 provided on one surface of the base material 11, and the in-cell retardation layer 12 is It comprises an alignment film 12a and a retardation film 12b. The retardation substrate 10A may have, in addition to the base material 11 and the in-cell retardation layer 12, other layers such as a color filter layer.

The substrate 11 is preferably a transparent substrate, and examples thereof include a glass substrate and a plastic substrate.

The in-cell retardation layer 12 has a function of changing the state of incident polarization by making two orthogonal polarization components have a phase difference.

The alignment film 12a is a base layer for controlling the alignment of reactive mesogens contained in the material of the retardation film 12b, and a general alignment film used to control the alignment of liquid crystalline molecules may be used. it can. Examples of the material of the alignment film 12a include polymers having a main chain such as polyimide, polyamic acid, and polysiloxane, and a photoalignment film material having a photoreactive site (functional group) in the main chain or side chain is preferable. Used.

The retardation film 12b is a layer in which a reactive mesogen (RM) is oriented and cured, and can be formed by a method described later.

The thickness of the retardation film 12b is preferably 1.0 μm or more and 3.0 μm or less, and more preferably 1.2 μm or more and 2.0 μm or less.

The phase difference of the phase difference film 12 b is not particularly limited, but it is preferable that the phase difference film 12 b have a phase difference of λ / 4. By setting the retardation of the retardation film 12b to λ / 4, reflection of external light can be effectively suppressed in a liquid crystal display using the retardation substrate 10A as an in-cell retardation layer. The phase difference of the phase difference film 12b can be measured using Axoscan (Mueller matrix polarimeter).

The orientation of the reactive mesogen in the retardation film 12b is controlled by the orientation film 12a disposed on the lower surface side of the retardation film 12b, but in the conventional method, the alignment regulating force of only the lower surface side is in the bulk. It is difficult to align the reactive mesogen molecules and reactive mesogen molecules at the air interface (upper surface side) completely uniformly, and in order to realize a high contrast display in the liquid crystal display device, the reaction constituting the retardation film 12b It has been required to improve the orientation of crystalline mesogens.

According to the method of manufacturing the retardation substrate 10A according to the present embodiment, the orientation of the reactive mesogen constituting the retardation film 12b can be improved. Next, a method of manufacturing the retardation substrate 10A according to the present embodiment will be described. In the method of manufacturing the retardation substrate 10A according to the present embodiment, a step (1) of aligning the alignment film 12a, and a step (2) of forming an uncured film containing reactive mesogen on the alignment film 12a The step (3) of forming the retardation film 12b by irradiating the uncured film with polarized ultraviolet light that causes the reactive mesogen to undergo a curing reaction.

<Step (1)>
In the step (1), the alignment film 12a is subjected to alignment treatment. The method for the alignment treatment of the alignment film 12a is not particularly limited, and may be rubbing treatment or photo alignment treatment.

The rubbing process is to press the alignment film 12a while rotating the rubbing roller. The rubbing roller may be, for example, a roller having a rubbing cloth with a pile woven on the surface, or a roller having irregularities on the surface, and a roller having a rayon rubbing cloth is preferably used.

The photoalignment process can be applied when the material of the alignment film 12a is a photoalignment film material. The photo alignment film material is structurally changed by being irradiated with light (electromagnetic wave) such as ultraviolet light and visible light, and is a material that exhibits a property (alignment control force) to control the alignment of liquid crystal molecules existing in the vicinity Or, it means all materials in which the magnitude and / or orientation of the orientation control force changes. The photoalignment film material contains, for example, a photoreactive site in which a reaction such as dimerization (dimer formation), isomerization, light fleece transition, decomposition occurs by light irradiation. Examples of photoreactive sites (functional groups) which are dimerized and isomerized by light irradiation include cinnamate, cinnamoyl, 4-chalcone, coumarin, stilbene and the like. As a photoreaction site (functional group) which is isomerized by light irradiation, azobenzene etc. are mentioned, for example. As a photoreaction site | part which carries out light fleece transition by light irradiation, a phenol ester structure etc. are mentioned, for example. As a photoreaction site to be decomposed by light irradiation, for example, a dianhydride containing a cyclobutane ring such as 1,2,3,4-cyclobutanetetracarboxylic acid-1,2: 3,4-dianhydride (CBDA), etc. Can be mentioned. Further, it is preferable that the photo alignment film material exhibits vertical alignment usable in the vertical alignment mode. As a photo alignment film material, the polyamide (polyamic acid) containing a photoreaction site | part, a polyimide, a polysiloxane derivative, a methyl methacrylate, polyvinyl alcohol etc. are mentioned, for example.

The optical alignment processing can be performed using, for example, an apparatus having a light source for irradiating light to the alignment film 12 a and having a function capable of performing continuous scan exposure over a plurality of pixels. As a specific aspect of the scan exposure, for example, an aspect in which a light beam emitted from a light source is moved onto the substrate surface while moving the substrate, and a light flux emitted from the light source is irradiated onto the substrate surface while moving the light source The aspect includes an aspect in which a light beam emitted from the light source is irradiated on the substrate surface while moving the light source and the substrate.

Heat treatment may be performed after the light alignment treatment. By heat treatment, it is possible to orient a part of the photoalignment film material which has not caused a photoreaction in a predetermined direction.

<Step (2)>
In the step (2), an uncured film containing reactive mesogen is formed on the alignment film 12a. The uncured film can be prepared by applying the retardation film composition on the substrate 11. As a method of applying the composition for retardation layer, any method generally known in the relevant field may be used. For example, spin coating method, bar coating method, die coater method, screen printing method, spray coater method, etc. There is.

The composition for retardation film is obtained by dissolving a reactive mesogen in a solvent. In addition to the photopolymerization initiator, the surfactant, etc., a component usually contained in a polymerizable composition which causes polymerization by light and heat may be appropriately added to the composition for the retardation layer.

Examples of the reactive mesogen include mesogenic groups such as biphenyl group, terphenyl group, naphthalene group, phenylbenzoate group, azobenzene group, derivatives thereof, and the like, which are frequently used as mesogenic components of liquid crystalline polymers, cinnamoyl groups, Acrylate, methacrylate, maleimide, N- having a side chain having a structure having a combination of chalcone group, cinnamylidene group, β- (2-phenyl) acryloyl group, cinnamic acid group, and photoreactive groups such as derivatives thereof, Mention may be made of polymers having a structure such as phenyl maleimide or siloxane in the main chain.

The reactive mesogen may be a homopolymer consisting of a single repeating unit or a copolymer consisting of two or more repeating units having different side chain structures. The above-mentioned copolymer includes any of alternating type, random type, graft type and the like. Further, in the above copolymer, the side chain relating to at least one repeating unit is a side chain having a structure having both the mesogen group and the photoreactive group, but the side chain relating to other repeating units is the above It may be one that does not have a mesogenic group or the above-mentioned photoreactive group.

Preferred specific examples of the reactive mesogen according to the present embodiment are shown below.

The reactive mesogen may be, for example, a copolymerizable (meth) acrylic acid polymer having a repeating unit represented by the following general formula (I).

Wherein R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group or a phenyl group substituted with a group selected from an alkyl group, an alkoxy group, a cyano group and a halogen atom, ring A And ring B are each independently a group represented by the following general formulas (M1) to (M5), p and q are each independently an integer of 1 to 12, and m and n Is the mole fraction of each monomer in the copolymer satisfying the relationship of 0.65 ≦ m ≦ 0.95, 0.05 ≦ n ≦ 0.35, and m + n = 1.)

(In the above formula, each of X ¹ to X ³⁸ is independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom or a cyano group.)

The reactive mesogen is preferably a copolymerizable (meth) acrylic acid polymer having a repeating unit represented by the following general formula (Ia).

(Wherein, R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group, or a phenyl group substituted with a group selected from an alkyl group, an alkoxy group, a cyano group and a halogen atom, X ^1A ~ and each respective independent X ^4A, a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom or a cyano group, ring B is a group represented by the following general formula (M1a) or (M5a), p and q are each independently an integer of 1 to 12, and m and n have a relationship of 0.65 ≦ m ≦ 0.95, 0.05 ≦ n ≦ 0.35, m + n = 1 The mole fraction of each monomer in the copolymer satisfying

(In the above formulas, each of X ^1B to X ^4B and X ^31B to X ^38B is independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom or a cyano group.)

Furthermore, the reactive mesogen is more preferably a copolymerizable (meth) acrylic acid polymer having a repeating unit represented by the following general formula (Ib) or (Ic).

(Wherein, R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group, or a phenyl group substituted with a group selected from an alkyl group, an alkoxy group, a cyano group and a halogen atom, X ^1A Each of to X ^4A and X ^31B to X ^38B is independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom or a cyano group, and p and q are each independently any of 1 to 12 It is an integer, and m and n are mole fractions of respective monomers in the copolymer satisfying the relationship of 0.65 ≦ m ≦ 0.95, 0.05 ≦ n ≦ 0.35, and m + n = 1. )

(Wherein, R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group, or a phenyl group substituted with a group selected from an alkyl group, an alkoxy group, a cyano group and a halogen atom, X ^1A Each of X ^4A and X ^1B to X ^4B is independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom or a cyano group, and p and q are each independently any of 1 to 12 It is an integer, and m and n are mole fractions of respective monomers in the copolymer satisfying the relationship of 0.65 ≦ m ≦ 0.95, 0.05 ≦ n ≦ 0.35, and m + n = 1. )

In the general formula of the present embodiment (I) (formula (I-a), formula (I-b) and the general formula including the (I-c). Forth.), As the ^{R 1,} a methyl group preferable. As R ² , a phenyl group substituted by an alkyl group or a group selected from an alkyl group, an alkoxy group, a cyano group and a halogen atom is preferable, and of these, an alkyl group or an alkoxy group or a cyano group substituted A phenyl group is more preferable, and a phenyl group substituted with an alkyl group or an alkoxy group is particularly preferable.

As each of X ^{31 B} to X ^{38 B} , a hydrogen atom or a halogen atom is preferable, and all hydrogen atoms are most preferable.

As p and q, any integer of 3 to 9 is preferable, and any integer of 5 to 7 is more preferable among them, and 6 is most preferable. The range of m is preferably in the range of 0.75 ≦ m ≦ 0.85, and most preferably 0.8. The corresponding preferable range of n is a range which is naturally determined from m + n = 1. That is, it is preferably in the range of 0.15 ≦ n ≦ 0.25, and most preferably 0.2.

In the general formulas (I-a), (I-b) or (I-c) of the embodiment, X ^1A to X ^4A are preferably a hydrogen atom or a halogen atom, and in particular, any of X ^1A to X ^4A Preferably, one is a halogen atom and the other is a hydrogen atom, or all are hydrogen atoms. Further, in the general formula (Ib) of the present embodiment, as X ^31B to X ^38B , a hydrogen atom or a halogen atom is preferable, and it is most preferable that all of them are hydrogen atoms. Further, in the general formula (Ic) of the present embodiment, as X ^1B to X ^4B , a hydrogen atom or a halogen atom is preferable, and it is most preferable that all of them are hydrogen atoms.

The alkyl group of the substituents of the phenyl group of the alkyl group or R ² in R ^2, include an alkyl group having 1 to 12 carbon atoms, of which preferably has 1 to 6 carbon atoms, more preferably a carbon number The thing of 1-4 is most preferably a methyl group. The alkoxy group of the substituent of the phenyl group of R ² includes an alkoxy group having 1 to 12 carbon atoms, preferably one having 1 to 6 carbon atoms, more preferably one having 1 to 4 carbon atoms. And most preferably a methoxy group. The halogen atom of the substituents of the phenyl group of R ^2, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, of which a fluorine atom is preferable.

In X ¹ to X ³⁸ , examples of the alkyl group include those having 1 to 4 carbon atoms, of which methyl group is the most preferable, and examples of the alkoxy group include those having 1 to 4 carbon atoms, of which the methoxy group is The halogen atom is most preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, among which a fluorine atom is preferable.

In the present specification, X ^1A to X ^4A represent, for X ¹ to X ³⁸ which are substituents on ring A or ring B, a case where they are substituents on ring A, X ^1B to X ^4B and X ^{31 B} to X ³⁸ B represent the case where they are substituents on ring B. ^Therefore, description of the X 1 ^{~ X 38} is one which can be applied also to directly ^{X 1A ~ X 4A, X 1B} ~ X 4B and ^X 31B ^{~ X 38B.}

The content of the reactive mesogen in the retardation film composition is preferably 10% by weight or more and 40% by weight or less, more preferably 15% by weight or more and 35% by weight or less, and 20% by weight More preferably, it is 30% by weight or less.

Examples of the solvent used for the composition for the retardation film include toluene, ethylbenzene, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol methyl ether, dibutyl ether, acetone, methyl ethyl ketone, ethanol, propanol, cyclohexane, cyclopentanone, methyl cyclohexane Tetrahydrofuran, dioxane, cyclohexanone, n-hexane, ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, methoxybutyl acetate, N-methylpyrrolidone, dimethylacetamide and the like. Among them, methyl ethyl ketone and cyclohexanone are preferable from the viewpoint of toxicity and environmental load and / or from the viewpoint of solubility resistance to a resin substrate (for example, polyethylene terephthalate (PET), cycloolefin polymer (COP), etc.). Any of these may be used alone, or two or more may be used in combination. In particular, the copolymerizable (meth) acrylic acid polymer having a repeating unit represented by the above general formula (I) has an excellent feature of being soluble in methyl ethyl ketone and cyclohexanone.

The content of the solvent in the composition for the retardation layer is not particularly limited as long as the reactive mesogen is dissolved, but usually, for example, 70% by weight or more and 99% by weight or less based on the total weight of the reactive mesogen is there.

As a photoinitiator used for the said composition for retardation film, in order to form a uniform film | membrane by light irradiation of a small amount, the general purpose photopolymerization agent generally known can be used all. Specific examples thereof include, for example, azonitrile-based photopolymerization initiators such as 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), Irgacure 907 (Ciba Specialty · · · Α-amino ketone photopolymerization initiators such as Chemicals, Irgacure 369 (Ciba Specialty Chemicals), 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 1- (4) -Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one and the like Acetophenone photoinitiators, benzoin, benzoi Benzoin photopolymerization initiators such as methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzyl dimethyl ketal, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl- Benzophenone photopolymerization initiators such as 4'-methyl diphenyl sulfide, 2-chlorothioxanthones, 2-methyl thioxanthones, isopropyl thioxanthones, thioxanthone photopolymerization initiators such as 2,4-diisopropyl thioxanthone, 2,4,6-Trichloro-s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) ) -S-triazine, 2- (p-tolyl) -4,6-bis (trichloromethyl) -triazine, 2-piperonyl-4,6-bis (trichloromethyl) -s-triazine, 2,4 -Bis (trichloromethyl) -6-styryl-s-triazine, 2- (naphth-1-yl) -4,6-bis (trichloromethyl) -s-triazine, 2- (4-methoxy-naphtho-1-) Yl) -4,6-bis (trichloromethyl) -s-triazine, 2,4-trichloromethyl- (piperonyl) -6-triazine, 2,4-trichloromethyl (4'-methoxystyryl) -6-triazine etc. Triazine-based photopolymerization initiators, carbazole-based photopolymerization initiators, imidazole-based photopolymerization initiators, etc .; and further, α-acyloxy esters, acyl phosphine oxides, methyl Phenylglyoxylate, benzyl, 9,10-phenanthrenequinone, camphorquinone, ethyl anthraquinone, 4,4'-diethylisophthalophenone, 3,3 ', 4,4'-tetra (t-butylperoxy) Photopolymerization initiators such as carbonyl) benzophenone, 4,4'-diethylamino benzophenone, thioxanthone and the like can be mentioned. Any of the photopolymerization initiators may be used alone, or two or more of them may be used in combination.

As surfactant used for the said composition for retardation film, surfactant generally used in order to form a uniform film | membrane can be used all. Specific examples thereof include sodium lauryl sulfate, ammonium lauryl sulfate, triethanolamine lauryl sulfate, polyoxyethylene alkyl ether sulfate, alkyl ether phosphate, sodium oleyl succinate, potassium myristate, coconut oil fatty acid potassium, sodium lauroyl sulfate Anionic surfactants such as cosinate; polyethylene glycol monolaurate, sorbitan stearate, glyceryl myristate, glyceryl dioleate, sorbitan stearate, nonionic surfactants such as sorbitan oleate; stearyltrimethyl ammonium chloride, behenyl chloride Cationic domains such as trimethyl ammonium, stearyl dimethyl benzyl ammonium chloride, cetyl trimethyl ammonium chloride Activators; Alkylbetaines such as laurylbetaine, alkylsulfobetaines, cocamidopropylbetaine, alkyldimethylaminoacetic acid betaines, etc., amphoteric surfactants such as alkylimidazolines, sodium lauroyl sarcosine, sodium cocoamphoacetate, etc. Furthermore, BYK-361, BYK Surfactants such as -306, BYK-307 (manufactured by Bick Chemie Japan), Florard FC 430 (manufactured by Sumitomo 3M), Megafac F 171, R 08 (manufactured by DIC) and the like can be mentioned. Any of these surfactants may be used alone, or two or more thereof may be used in combination.

The content of the optional components other than the reactive mesogen and the solvent in the composition for the retardation layer is not particularly limited, and usually, for example, the photopolymerization initiator is contained in an amount of 1% by weight or more based on the total weight of the reactive mesogen. The content of the surfactant is preferably 0.1% by weight or more and 5% by weight or less.

Next, the composition for retardation film applied on the alignment film 12a is dried under reduced pressure or naturally dried and then dried by heating to remove the solvent contained in the composition for retardation layer. It is preferred to leave. It is more preferable that the composition for retardation layer applied on the base material 11 be heat-dried after natural drying. Here, "distilling off the solvent" means removing the solvent to such an extent that the remaining solvent can not be detected, and for example, it becomes below the detection limit in measurement by gas chromatography. When the solvent is distilled off from the composition for retardation film, an uncured film is formed on the alignment film 12a. In the present specification, a film that contains a reactive mesogen and is not cured by irradiation with polarized ultraviolet light is referred to as an "uncured film".

<Step (3)>
In the step (3), the uncured film is irradiated with polarized ultraviolet light that causes the reactive mesogen to undergo a curing reaction to form a retardation film. The wavelength of polarized ultraviolet light (PUV: Polarized UV) irradiated to the above-mentioned uncured film is not particularly limited as long as the reactive mesogen can be caused to cure by irradiation, and even near ultraviolet light (wavelength: 200 to 380 nm) It may be far ultraviolet (wavelength: 10 to 200 nm).

The polarized ultraviolet light preferably has a wavelength longer than the light absorption wavelength of the alignment film 12a. When the wavelength of the polarized ultraviolet light overlaps with the light absorption wavelength of the alignment film 12a, the alignment orientation of the alignment film 12a set in the previous alignment process may be changed by the polarized ultraviolet light irradiated later. The light absorption of the alignment film 12a may interfere with the curing reaction of the reactive mesogen. Further, when the wavelength of the polarized ultraviolet light is shorter than the light absorption wavelength of the alignment film 12a, the bonding of the polymers constituting the alignment film 12a is broken by the polarized ultraviolet light, and the alignment regulating force of the alignment film 12a May decrease. As the alignment film 12a, one having a light absorption wavelength of 220 to 260 nm is suitably used.

The irradiation direction θ of the polarized ultraviolet light is preferably + 45 ° ≦ θ ≦ + 90 ° or −45 ° ≦ θ ≦ 90 ° when the alignment treatment direction of the alignment film 12a is defined as 0 °. Thereby, the orientation of the reactive mesogen constituting the retardation film 12b can be more effectively improved. As a result, it is possible to more effectively improve the display contrast of the liquid crystal display device. When the material of the alignment film 12a is a photoalignment film material, the alignment treatment orientation of the alignment film 12a is the irradiation orientation of polarized ultraviolet light when forming the alignment film 12a. FIG. 2 is a view for explaining the relationship between the irradiation direction of polarized ultraviolet light (1st PUV) when forming the alignment film 12a, the irradiation direction of polarized ultraviolet light (2nd PUV) when forming the retardation film 12b, and the irradiation direction θ. In FIG. 2, an angle formed in the counterclockwise direction is a positive angle, and an angle formed in the clockwise direction is a negative angle.

The irradiation direction of the polarized ultraviolet light is obtained by projecting the vibration direction of the electric field of the polarized ultraviolet light onto the uncured film. The polarized ultraviolet light may be irradiated from the direction perpendicular to the surface of the uncured film or may be irradiated from an oblique direction. The alignment treatment orientation of the alignment film 12a is obtained by projecting the vibration direction of the electric field of the polarized light irradiated in the light alignment treatment on the alignment film 12a in the case of the light alignment treatment. In addition, the polarized light irradiated in the case of a photo-alignment process may be irradiated from the orthogonal | vertical direction with respect to the surface of the alignment film 12a, and may be irradiated from a diagonal direction. It is preferable that the long axes of the molecules of the reactive mesogen to be aligned by the alignment film 12a be oriented in the direction orthogonal to the alignment treatment direction of the alignment film 12a.

As a light source used for irradiation of the said polarized ultraviolet light, a xenon lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp etc. are mentioned, for example. The light of such a light source may be adjusted in the optical path, the wavelength range, the degree of polarization, etc., using an optical member such as a filter or a prism.

The irradiation energy of the polarized ultraviolet light may be appropriately set according to the type of the reactive mesogen, the coating amount, and the like, and is, for example, 100 mJ / cm ² to 10 J / cm ² .

In addition, when irradiating the said polarization | polarized-light ultraviolet-ray, if a photomask is used, reactive mesogen can be orientated in pattern shape to 2 or more different directions.

Alternatively, heat treatment may be performed after irradiation with polarized ultraviolet light.

According to this embodiment, the retardation substrate capable of high contrast display can be obtained by the method of irradiating the reactive mesogen with polarized ultraviolet light. In addition, in the process of curing reactive mesogens, if the irradiation direction θ of polarized ultraviolet light is 90 ° (θ = 90 °), the reactivity is higher than when non-polarized ultraviolet light or polarized ultraviolet light of other irradiation orientation θ is used. The mesogen molecules can be aligned more uniformly, and the contrast of the liquid crystal display can be improved.

Second Embodiment
The second embodiment relates to a liquid crystal display device provided with a retardation substrate 10B formed by adding a member such as a color filter to the retardation substrate 10A of the first embodiment. Therefore, in the present embodiment, the features unique to the present embodiment will be mainly described, and the contents overlapping with the first embodiment will not be appropriately described.

FIG. 3 is a schematic cross-sectional view showing the liquid crystal display device of the second embodiment. As shown in FIG. 3, in the liquid crystal display device 1, a first polarizer 20, an out-cell retardation layer 30, a retardation substrate (first substrate) 10 B, a liquid crystal layer 50, It has a second substrate 60, a second polarizer 70 and a backlight 80.

As the first polarizer 20 and the second polarizer 70, for example, polarizers obtained by dyeing and adsorbing an anisotropic material such as iodine complex (or dye) on a polyvinyl alcohol (PVA) film and then stretching orientation ( An absorption type polarizing plate) etc. can be used.

The out-cell retardation layer 30 is a layer that changes the state of incident polarization by providing a phase difference between two orthogonal polarization components using a birefringence material or the like. As the out-cell retardation layer 30, a liquid crystalline polymer as used in the retardation film 12b may be used, and even if a stretched polymer film generally used in the field of liquid crystal display devices is used. Good. Examples of the material of the above-mentioned polymer film include cycloolefin polymers, polycarbonates, polysulfones, polyether sulfones, polyethylene terephthalates, polyethylenes, polyvinyl alcohols, norbornenes, norbornenes, triacetylcelluloses, diacetylcelluloses and the like, among which cycloolefins Polymers are preferred. The retardation layer formed of a cycloolefin polymer is excellent in durability, and has an advantage that the change in retardation when exposed to a high temperature environment or a high temperature and high humidity environment for a long time is small. As a film of a cycloolefin polymer, "Zeonor film (registered trademark)" manufactured by Zeon Corporation of Japan, "ARTON (registered trademark) film" manufactured by JSR Corporation, and the like are known.

The retardation substrate 10B includes a substrate 11, a color filter / black matrix layer 42, an overcoat layer 43, an in-cell retardation layer 12, and an alignment film 51 for liquid crystal alignment in order from the observation surface side to the back side.

The color filter / black matrix layer 42 has a configuration in which a red color filter, a green color filter and a blue color filter are arranged in a plane and partitioned by a black matrix. The red color filter, the green color filter, the blue color filter, and the black matrix are made of, for example, a transparent resin containing a pigment. Usually, a combination of a red color filter, a green color filter and a blue color filter is disposed in all the pixels, and each pixel is mixed by controlling the amount of color light transmitted through the red color filter, the green color filter and the blue color filter. The desired color is obtained at. For example, a black photosensitive acrylic resin can be used as the black matrix.

The overcoat layer 43 covers the surface of the color filter / black matrix layer 42 on the liquid crystal layer 50 side. By providing the overcoat layer 43, elution of impurities in the color filter / black matrix layer 42 into the liquid crystal layer 50 can be prevented. As a material of overcoat layer 43, transparent resin is suitable.

The alignment film 51 for liquid crystal alignment has a function of controlling the alignment of liquid crystal molecules in the liquid crystal layer 50, and when the voltage applied to the liquid crystal layer 50 is less than the threshold voltage (including no voltage application), alignment for liquid crystal alignment is mainly performed. The action of the film 51 controls the alignment of liquid crystal molecules in the liquid crystal layer 50. The alignment film 51 for liquid crystal alignment is a layer subjected to alignment processing for controlling the alignment of liquid crystal molecules, and as the alignment film 51 for liquid crystal alignment, an alignment film generally used in the field of liquid crystal display panels such as polyimide is used. It can be used. The film thickness of the alignment film 51 for liquid crystal alignment is preferably 50 nm or more and 200 nm or less, and more preferably 80 nm or more and 120 nm or less.

The liquid crystal layer 50 contains a liquid crystal composition, applies a voltage to the liquid crystal layer 50, and changes the alignment state of liquid crystal molecules in the liquid crystal composition according to the applied voltage to transmit light. Control.

The liquid crystal molecules may have a positive value or a negative value of dielectric anisotropy (Δε) defined by the following formula. Note that liquid crystal molecules having positive dielectric anisotropy are also called positive liquid crystals, and liquid crystal molecules having negative dielectric anisotropy are also called negative liquid crystals. In addition, liquid crystal molecules are homogeneously aligned in a state where no voltage is applied (voltage not applied), and the direction of the major axis of the liquid crystal molecules in the voltage no applied state is also the direction of the initial alignment of liquid crystal molecules. Say.
Δε = (dielectric constant in the long axis direction)-(dielectric constant in the short axis direction)

Liquid crystal molecules having positive dielectric anisotropy are preferably used because they can further increase the response speed. In addition, liquid crystal molecules having negative dielectric anisotropy do not easily disturb the alignment state of the liquid crystal molecules even when disturbance occurs in the application of an electric field, and liquid crystals having positive dielectric anisotropy It is preferably used because light scattering is less likely to occur compared to molecules (in order to improve the transmittance).

The second substrate 60 is a thin film transistor array substrate, and the second substrate 60 includes an alignment film 51 for liquid crystal alignment, a thin film transistor layer 61 having thin film transistors (TFT: Thin Film Transistor) in order from the viewing surface side to the back surface side. A transparent substrate 62 is provided.

The thin film transistor layer 61 is a layer including at least a TFT which is a switching element used to switch on / off of a pixel of the liquid crystal display device, and electrically separates wirings and electrodes connected to the TFT. And the insulating film of

The liquid crystal drive mode of the liquid crystal display device according to the embodiment is not particularly limited. For example, FFS (Fringe Field Switching) mode, IPS (In-Plane Switching) mode, OCB (Optically Compensated Birefringence) mode, TN mode, MVA ( Multi-domain Vertical Alignment) mode, VA (Vertical Alignment) mode and the like can be mentioned, and a horizontal alignment mode such as FFS mode or IPS mode is preferably used.

In the horizontal alignment mode, a pair of electrodes that generate a horizontal electric field in the liquid crystal layer 50 by applying a voltage is used. In the FFS mode, the second substrate 60 includes a common electrode (planar electrode), an insulating film covering the common electrode, and a pixel electrode (comb electrode) disposed on the surface of the insulating film on the liquid crystal layer 50 side. Equipped with According to such a configuration, a horizontal electric field (fringe electric field) can be generated in the liquid crystal layer 50 by applying a voltage between the common electrode and the pixel electrode that form the pair of electrodes. Therefore, by adjusting the voltage applied between the common electrode and the pixel electrode, the alignment of liquid crystal molecules in the liquid crystal layer 50 can be controlled.

Examples of the material of the common electrode and the pixel electrode include indium tin oxide (ITO) and indium zinc oxide (IZO). As a material of an insulating film, an organic insulating film, a nitride film, etc. are mentioned, for example.

Further, in the case of the IPS mode, by applying a voltage to the pair of comb electrodes, a transverse electric field is generated in the liquid crystal layer 50, and the alignment of liquid crystal molecules in the liquid crystal layer 50 can be controlled.

The transparent substrate 62 is preferably a transparent substrate, and examples thereof include glass substrates and plastic substrates.

The type of the backlight 80 is not particularly limited, and examples thereof include an edge light type and a direct type. The type of light source of the backlight 80 is not particularly limited, and examples thereof include a light emitting diode (LED), a cold cathode tube (CCFL), and the like.

The polarization axis of the first polarizer 20 and the polarization axis of the second polarizer 70 preferably form an angle of 88 ° or more and 92 ° or less, and more preferably 89 ° or more and 91 ° or less It is more preferable to make an angle of not less than 89.7 ° and not more than 90.3 °. According to such a configuration, a good black display state can be realized in the no voltage applied state.

The out-cell retardation layer 30 is preferably a retardation layer (λ / 4 plate) that imparts an in-plane retardation of 1⁄4 wavelength to light of at least 550 nm, specifically, at least 550 nm Preferably, an in-plane retardation of 100 nm or more and 176 nm or less is given to the light of (1). By the out-cell retardation layer 30 functioning as a λ / 4 plate, the combination of the first polarizer 20 and the out-cell retardation layer 30 can function as a circularly polarizing plate. Thereby, the internal reflection of the liquid crystal display device can be reduced, so that a good black display in which the reflection (reflection) of external light is suppressed can be realized.

Further, in the circularly polarized FFS mode liquid crystal display in which only the outcell retardation layer 30 is incorporated into the FFS mode liquid crystal display, black display can not be performed, so an in-cell retardation layer 12 (retardation film 12b) should be provided. Thus, the performance of the liquid crystal display device in the circularly polarized light FFS mode can be improved. It is preferable that the slow axis of the outcell retardation layer 30 be orthogonal to the slow axis of the retardation film 12b, and that the retardation value of the outcell retardation layer 30 be equal to the retardation value of the retardation film 12b. As a result, the out-cell retardation layer 30 and the retardation film 12b can cancel each other's phase difference with respect to light incident from the normal direction of the liquid crystal display device, and both of them are substantially optically. A nonexistent state is realized. That is, a configuration is realized that is optically equivalent to the conventional liquid crystal display panel in the transverse electric field mode with respect to light entering the liquid crystal display device from the backlight 80. Therefore, display in a transverse electric field mode using a circularly polarizing plate can be realized.

In the present embodiment, the case where the retardation substrate 10B is a color filter substrate is shown, but in the retardation substrate manufactured according to the present invention, if the alignment film and the retardation film are laminated on the base material It is not particularly limited, and may be applied to a thin film transistor array substrate.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by these examples.

(Examples 1 to 7 and Comparative Example 1)
The configurations of the retardation substrates of Examples 1 to 7 and Comparative Example 1 are as shown in FIG. The base 11 was a glass substrate. Photodegradable polyimide was used as the material of the alignment film 12a. As a material of the retardation film 12b, a reactive mesogen containing an acrylic ester as a main component was used. The light absorption wavelength of the photolytic polyimide was 220 to 260 nm, and the light absorption wavelength of the reactive mesogen was 280 to 330 nm.

The manufacturing flow of the retardation substrates of Examples 1 to 7 and Comparative Example 1 is as follows. After forming the alignment film 12a on the substrate 11, the retardation film 12b was formed on the alignment film 12a.

(Method of forming alignment film 12a)
1. An alignment film material was formed on the substrate 11 by spin coating (rotational speed: 2000 rpm).
2. The film was calcined on a hot plate (temperature: 80 ° C., time: 90 sec)
3. The first main baking was performed on the film on a hot plate (temperature: 230 ° C., time: 40 min)
4. The film was irradiated with polarized ultraviolet light (irradiation amount: 200 mJ, wavelength 254 nm).
5. The first main baking was performed on the film on a hot plate (temperature: 230 ° C., time: 40 min)

(Method of forming retardation film 12b)
1. An uncured film was formed on the alignment film 12a by depositing a reactive mesogen by spin coating (rotational speed: 3500 rpm).
2. The uncured film was calcined on a hot plate (temperature: 80 ° C., time: 2 min)
3. The reactive mesogen was cured by irradiating polarized ultraviolet (Examples 1 to 7) or non-polarized ultraviolet (Comparative Example 1) to the uncured film at room temperature to form a retardation film 12 b (irradiation) Amount: 400 mJ, wavelength 313 nm).

In Examples 1 to 7, the irradiation direction θ of the polarized ultraviolet light when the retardation film 12 b was formed was changed as follows.
Example 1: θ = 0 °
Example 2: θ = 15 °
Example 3: θ = 30 °
Example 4: θ = 45 °
Example 5: θ = 60 °
Example 6: θ = 75 °
Example 7: θ = 90 °

The irradiation azimuth θ (unit: °) of the polarized ultraviolet light at the time of forming the retardation film 12 b is defined when the irradiation azimuth of the polarized ultraviolet light (the alignment treatment azimuth of the alignment film) at the time of forming the alignment film 12 a is 0 °. It is an azimuth angle. FIG. 4 is a view for explaining the relationship between the irradiation direction of polarized ultraviolet light on the alignment film 12a and the irradiation direction of polarized ultraviolet light on the retardation film 12b in Example 1 (θ = 0 °). FIG. 5 is a view for explaining the relationship between the irradiation direction of polarized ultraviolet light on the alignment film 12a and the irradiation direction of polarized ultraviolet light on the retardation film 12b in Example 4 (θ = 45 °). FIG. 6 is a view for explaining the relationship between the irradiation direction of polarized ultraviolet light on the alignment film 12a and the irradiation direction of polarized ultraviolet light on the retardation film 12b in Example 7 (θ = 90 °).

The phase differences of the retardation substrates produced in Examples 1, 4, 7 and Comparative Example 1 were measured. The phase difference was measured with respect to light having a wavelength of 550 nm using a polarization / phase difference measurement system (manufactured by Opto Science, “Axoscan”). The following Table 1 shows the measurement results of the retardation of the retardation substrates produced in Examples 1, 4, 7 and Comparative Example 1.

The contrast (CR) of the retardation substrates produced in Examples 1 to 7 and Comparative Example 1 was calculated. The contrast is the luminance (black luminance) when the retardation substrate is sandwiched between crossed Nicol polarizers using a spectroradiometer ("SR-UL1" manufactured by Topcon Technohouse Co., Ltd.) and the parallel Nicol polarization of the retardation substrate The luminance (white luminance) when sandwiched between the plates was measured and calculated using the following equation.
CR = (white brightness) / (black brightness)
When the retardation substrate was sandwiched between the crossed Nicol polarizing plates, the retardation axis of the retardation substrate (retardation film) was adjusted to be parallel to the absorption axis of one of the polarizing plates. On the other hand, when the retardation substrate was sandwiched between parallel Nicol polarizing plates, the slow axis of the retardation substrate (retardation film) was adjusted and set so as to be parallel to the absorption axes of both polarizing plates. Table 1 below shows the measurement results of the contrast of the retardation substrates produced in Examples 1 to 7 and Comparative Example 1. FIG. 7 is a graph showing the measurement results of the contrast of the retardation substrates produced in Examples 1 to 7.

The relationship between the irradiation direction θ of the polarized ultraviolet light when forming the retardation film 12 b and the obtained CR will be described below using “CR (θ °)”. From the results shown in Table 1 and FIG. 7, it was found that CR (90 °)> CR (45 °)> CR (0 °). That is, when the polarized light is irradiated in parallel to the reactive mesogen molecules 13, the contrast (CR) of the retardation substrate is the highest. In addition, CR (Examples 1 to 7) in which the reactive mesogen was cured by polarized ultraviolet light was more preferable than CR (comparative example 1) in which the reactive mesogen was cured by nonpolarizing ultraviolet light. It was confirmed that the irradiation azimuth θ was also high.

(Examples 8 to 14 and Comparative Example 2)
The configurations of the retardation substrates of Examples 8 to 14 and Comparative Example 2 were as shown in FIG. The base 11 was a glass substrate. Photodegradable polyimide was used as the material of the alignment film 12a. As a material of the retardation film 12b, a reactive mesogen containing a liquid crystal acrylic monomer as a main component was used. The light absorption wavelength of the photolytic polyimide was 220 to 260 nm, and the light absorption wavelength of the reactive mesogen was 355 to 375 nm.

The production flow of the retardation substrates of Examples 8 to 14 and Comparative Example 2 is as follows. After forming the alignment film 12a on the substrate 11, the retardation film 12b was formed on the alignment film 12a.

(Method of forming alignment film 12a)
1. An alignment film material was formed on the substrate 11 by spin coating (rotational speed: 1900 rpm).
2. The film was calcined on a hot plate (temperature: 80 ° C., time: 90 sec)
3. The first main baking was performed on the film on a hot plate (temperature: 230 ° C., time: 40 min)
4. The film was irradiated with polarized ultraviolet light (irradiation amount: 200 mJ, wavelength 254 nm).
5. The first main baking was performed on the film on a hot plate (temperature: 230 ° C., time: 40 min)

(Method of forming retardation film 12b)
1. An uncured film was formed on the alignment film 12a by depositing a reactive mesogen by spin coating (rotational speed: 850 rpm).
2. The uncured film was calcined on a hot plate (temperature: 60 ° C., time: 3 min)
3. The reactive mesogen was cured by irradiating polarized ultraviolet (Examples 8 to 14) or non-polarized ultraviolet (Comparative Example 2) to the uncured film at room temperature to form a retardation film 12 b (irradiation) Amount: 500 mJ, wavelength 365 nm).

In Examples 8 to 14, the irradiation direction θ of the polarized ultraviolet light when the retardation film 12 b was formed was changed as follows.
Example 8: θ = 0 °
Example 9: θ = 15 °
Example 10: θ = 30 °
Example 11: θ = 45 °
Example 12: θ = 60 °
Example 13: θ = 75 °
Example 14: θ = 90 °

The phase differences of the retardation substrates produced in Examples 8, 11, 14 and Comparative Example 2 were measured in the same manner as in Example 1. Further, the contrast (CR) of the retardation substrates produced in Examples 8 to 14 and Comparative Example 2 was calculated in the same manner as in Example 1. Table 2 below shows the measurement results of the retardation of the retardation substrates manufactured in Examples 8, 11 and 14 and Comparative Example 2, and the measurement results of the contrast of the retardation substrates manufactured in Examples 8 to 14 and Comparative Example 2. Is shown. FIG. 8 is a graph showing the measurement results of the contrast of the retardation substrates produced in Examples 8 to 14.

From the results shown in Table 2 and FIG. 8, it was found that CR (90 °)> CR (45 °)> CR (0 °). That is, when the polarized light is irradiated in parallel to the reactive mesogen molecules 13, the contrast (CR) of the retardation substrate is the highest. In addition, CR (Examples 8 to 14) when curing reactive mesogen with polarized ultraviolet light is more than any of CR (Comparative Example 2) when curing reactive mesogen with non-polarized ultraviolet light. It was confirmed that the irradiation azimuth θ was also high.

(Examples 15 to 21 and Comparative Example 3)
The configurations of the retardation substrates of Examples 15 to 21 and Comparative Example 3 were as shown in FIG. The base 11 was a glass substrate. Photodegradable polyimide was used as the material of the alignment film 12a. As a material of the retardation film 12b, a reactive mesogen mainly composed of a liquid crystal acrylic monomer different from that of Example 8 and the like was used. The light absorption wavelength of the photolytic polyimide was 220 to 260 nm, and the light absorption wavelength of the reactive mesogen was 355 to 365 nm.

The manufacturing flow of the retardation substrates of Examples 15 to 21 and Comparative Example 3 is as follows. After forming the alignment film 12a on the base material 11, the retardation film 12b was formed on the alignment film 12a.

(Method of forming alignment film 12a)
1. An alignment film material was formed on the substrate 11 by spin coating (rotational speed: 1900 rpm).
2. The film was calcined on a hot plate (temperature: 80 ° C., time: 90 sec)
3. The first main baking was performed on the film on a hot plate (temperature: 230 ° C., time: 40 min)
4. The film was irradiated with polarized ultraviolet light (irradiation amount: 200 mJ, wavelength 254 nm).
5. The first main baking was performed on the film on a hot plate (temperature: 230 ° C., time: 40 min)

(Method of forming retardation film 12b)
1. An uncured film was formed on the alignment film 12a by depositing a reactive mesogen by spin coating (rotational speed: 3000 rpm).
2. The uncured film was calcined on a hot plate (temperature: 60 ° C., time: 2 min)
3. The reactive mesogen was cured by irradiating the uncured film with polarized ultraviolet light (Examples 15 to 21) or non-polarized ultraviolet light (Comparative Example 3) at room temperature to form a retardation film 12b (irradiation) Amount: 500 mJ, wavelength 365 nm).

In Examples 15 to 21, the irradiation direction θ of the polarized ultraviolet light when the retardation film 12 b was formed was changed as follows.
Example 15: θ = 0 °
Example 16: θ = 15 °
Example 17: θ = 30 °
Example 18: θ = 45 °
Example 19: θ = 60 °
Example 20: θ = 75 °
Example 21: θ = 90 °

The phase differences of the retardation substrates produced in Examples 15, 18, 21 and Comparative Example 3 were measured in the same manner as in Example 1. Further, the contrast (CR) of the retardation substrates produced in Examples 15 to 21 and Comparative Example 3 was calculated in the same manner as in Example 1. The following Table 3 shows the measurement results of retardation of the retardation substrates manufactured in Examples 15, 18, 21 and Comparative Example 3, and the measurement results of contrast of the retardation substrates manufactured in Examples 15 to 21 and Comparative Example 3. Is shown. FIG. 9 is a graph showing the measurement results of the contrast of the retardation substrates produced in Examples 15 to 21.

From the results shown in Table 3 and FIG. 9, it was found that CR (90 °)> CR (45 °)> CR (0 °). That is, when the polarized light is irradiated in parallel to the reactive mesogen molecules 13, the contrast (CR) of the retardation substrate is the highest. In addition, CR (Examples 15 to 21) when curing reactive mesogen with polarized ultraviolet light is more than any of CR (Comparative Example 3) when curing reactive mesogen with non-polarized ultraviolet light. It was confirmed that the irradiation azimuth θ was also high.

[Supplementary note]
One aspect of the present invention is a method for producing a retardation substrate in which an alignment film and a retardation film are laminated on a base material, and the process of aligning the alignment film, and reactive mesogen on the alignment film. A method for producing a retardation substrate, comprising: forming an uncured film containing the above-mentioned, and irradiating the uncured film with polarized ultraviolet light causing a curing reaction of the reactive mesogen to form the retardation film. It is.

The irradiation azimuth θ of the polarized ultraviolet light may be + 45 ° ≦ θ ≦ + 90 ° or −45 ° ≦ θ ≦ 90 ° when the alignment treatment azimuth of the alignment film is defined as 0 °. The polarized ultraviolet light may have a wavelength longer than the light absorption wavelength of the alignment film. The alignment film may have a light absorption wavelength of 220 to 260 nm. The retardation film may be a λ / 4 plate.

Another aspect of the present invention is a method of manufacturing a liquid crystal display including a step of manufacturing a retardation substrate using the above-described method of manufacturing a retardation substrate.

1: Liquid crystal display device 10A, 10B: retardation substrate 11: base 12: in-cell retardation layer 12a: alignment film 12b: retardation film 13: reactive mesogen molecule 20: first polarizer (analyzer)
30: out-cell retardation layer 42: color filter / black matrix layer 43: overcoat layer 50: liquid crystal layer 51: alignment film for liquid crystal alignment 60: second substrate 61: thin film transistor layer 62: transparent substrate 70: second polarizer (Polarizer)
80: Backlight

Claims (6)

1. A method for producing a retardation substrate, in which an alignment film and a retardation film are laminated on a substrate,
   Aligning the alignment film;
   Forming an uncured film containing reactive mesogen on the alignment film;
   And irradiating the uncured film with polarized ultraviolet light that causes the reactive mesogen to undergo a curing reaction to form the retardation film.
2. The irradiation direction θ of the polarized ultraviolet light is such that + 45 ° ≦ θ ≦ + 90 ° or −45 ° ≦ θ ≦ 90 ° when the alignment treatment direction of the alignment film is defined as 0 °. The manufacturing method of the phase difference board | substrate as described in 1.
3. The method according to claim 1, wherein the polarized ultraviolet light has a wavelength longer than a light absorption wavelength of the alignment film.
4. The method for producing a retardation substrate according to any one of claims 1 to 3, wherein the alignment film has a light absorption wavelength of 220 to 260 nm.
5. The method for manufacturing a retardation substrate according to any one of claims 1 to 4, wherein the retardation film is a λ / 4 plate.
6. A method of manufacturing a liquid crystal display device comprising the step of manufacturing a retardation substrate using the method of manufacturing a retardation substrate according to any one of claims 1 to 5.

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