JP2006220891A - Composition for alignment layer, alignment layer, optical film, polarization plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film which has good optical compensation ability, excellent storage suitability and manufacturing suitability and can be stably manufactured, and to provide a polarization plate and a liquid crystal display device both obtained by using the film. <P>SOLUTION: A composition for an alignment layer is used for manufacturing the optical film which has a support, the alignment layer, and an optical anisotropic layer comprising a liquid crystalline composition containing a liquid crystalline compound. The composition for the alignment layer contains at least a polymer having a reactive group in a side chain, a compound having an ethylenically unsaturated bond, a photo-acid generating agent, and a solvent including water in an amount of ≥20 mass%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an alignment film composition used in the liquid crystal field, an alignment film, an optical film prepared from a liquid crystalline compound, a polarizing plate, and a liquid crystal display device. More specifically, an alignment film composition for obtaining a liquid crystal alignment film having high manufacturing suitability in optical film production, an optical film and a polarizing plate that contribute to an improvement in viewing angle characteristics of a liquid crystal display device, and an improvement in viewing angle characteristics The present invention relates to a liquid crystal display device.

  The phase difference plate is used in various liquid crystal display devices for eliminating image coloring and widening the viewing angle. Conventionally, stretched birefringent films have been used as retardation plates, but in recent years, instead of stretched birefringent films, an optical film having an optically anisotropic layer made of liquid crystalline molecules on a transparent support is used for retardation. It has been proposed to be used as a board. This optically anisotropic layer is usually formed by applying a composition containing liquid crystal molecules on an alignment film, heating the composition to a temperature higher than the alignment temperature, aligning the liquid crystalline molecules, and fixing the alignment state. Is done.

Various alignment films that define the alignment direction of the liquid crystal compound are known, such as an inorganic oblique deposition film using a metal oxide or fluoride such as SiO ₂ , TiO ₂ , MgF ₂ or the like as a deposition material, In addition, a thin film in which molecules are isomerized by light, such as an LB film made of an azobenzene derivative, and molecules are uniformly arranged with directionality can be mentioned. Among them, a polymer layer whose surface is rubbed is used in terms of productivity. preferable. Polyimide is often used as the polymer for the alignment film. In addition, the polyamide described in Patent Document 1, the polyvinyl alcohol described in Patent Document 2, 3, 4 or 5, etc., polystyrene, polyvinylcarbazole and the like are also used.

  Among them, the optical film described in Patent Document 3 using modified polyvinyl alcohol in which a part of the hydroxyl group is substituted with a crosslinkable group as an alignment film greatly increases the omnidirectional viewing angle. In this optical film, since a crosslinkable group is introduced into the alignment film, the polymer of the alignment film and the optically anisotropic layer are chemically bonded through the interface between these layers. Therefore, even if it is stored for a long time or used, it does not peel off.

  Further, in Patent Document 6, even when the polymer is not modified, a monomer or oligomer having an ethylenically unsaturated bond is added to the alignment film composition, and the coating film is irradiated with ultraviolet rays or electron beams. A method for improving the adhesion between the alignment film and the optically anisotropic layer by curing is disclosed. Patent Document 6 describes that, according to this method, when the polymer is modified, the adhesion between the alignment film and the optical functional layer can be further improved.

On the other hand, an optical film used as a retardation plate may be used individually in a liquid crystal display device or may also serve as a protective film for a polarizing plate. In the latter case, elution into the saponification bath and film peeling during the saponification treatment in the polarizing plate production process are problematic. When the above modified polyvinyl alcohol is used for the alignment film, or a monomer or oligomer having an ethylenically unsaturated bond is added to the alignment film composition, and the coating film is cured by ultraviolet rays or electron beams to form the alignment film. Even in this case, depending on the production conditions of the optical film or polarizing plate, elution into the saponification bath or film peeling may occur, which has been a problem to be solved.
Japanese Patent Laid-Open No. 3-9326 JP-A-3-291601 JP 9-152509 A Japanese Patent Laid-Open No. 2002-268068 JP-A-2002-350859 JP 2004-206100 A

  An object of the present invention is to provide an optical film that has a good optical compensation ability, is excellent in storage and manufacturing suitability and can be stably produced, and a polarizing plate and a liquid crystal display device using the optical film.

Means for solving the above problems are as follows.
[1] An alignment film composition used for the production of an optical film having an optically anisotropic layer comprising a liquid crystalline composition comprising a support, an alignment film, and a liquid crystal compound, wherein a reactive group is present in the side chain. An alignment film composition comprising at least a polymer having an ethylenic unsaturated bond, a photoacid generator, and a solvent containing 20% by mass or more of water.
[2] The alignment film composition according to [1], wherein the photoacid generator is a water-soluble compound.
[3] The alignment film composition according to [2], wherein the photoacid generator is an iodonium salt or a sulfonium salt.
[4] The orientation according to any one of [1] to [3], wherein the polymer is at least one selected from a polyvinyl alcohol derivative having a polymerizable group in a side chain, a poly (meth) acrylate derivative, and a polysaccharide. Film composition.
[5] A step of coating and drying the alignment film composition according to any one of [1] to [4] on a support to form a coating film, a step of irradiating the coating film with light, and the light irradiation An alignment film manufactured by a manufacturing method having a step of rubbing the coated film in this order.
[6] A step of coating and drying the alignment film composition according to any one of [1] to [4] on a support to form a coating film, a step of rubbing the coating film, and the rubbed coating film An alignment film manufactured by a manufacturing method having steps of irradiating light in this order.
[7] In an optical film having an optically anisotropic layer made of a liquid crystalline composition containing a support, an alignment film, and a liquid crystal compound, the alignment film is the alignment film according to [5] or [6] And the said optically anisotropic layer is formed from the polymer of the said liquid crystalline compound, The optical film characterized by the above-mentioned.
[8] The optical film according to [7], wherein the liquid crystalline compound includes a discotic liquid crystalline compound.
[9] The optical film according to [7], wherein the liquid crystalline compound includes a rod-shaped liquid crystalline compound.
[10] The optical film according to [7], wherein the liquid crystal composition is a liquid crystal composition containing a rod-like liquid crystal compound and a chiral agent.
[11] The front retardation (Re) of the optically anisotropic layer is not 0, and from a direction inclined + 40 ° with respect to the normal direction of the optical film with the in-plane slow axis as the tilt axis (rotation axis) Retardation value measured by making light of wavelength λnm incident, and light of wavelength λnm from the direction inclined −40 ° with respect to the normal direction of the optical film with the in-plane slow axis as the tilt axis (rotation axis) The optical film according to any one of [7] to [10], wherein the retardation values measured upon incidence are substantially equal.
[12] A polarizing plate comprising the optical film according to any one of [7] to [11] and a polarizing film.
[13] A liquid crystal display device having the optical film according to any one of [7] to [11] or the polarizing plate according to [12].
[14] The liquid crystal display device according to [13], which is in a VA mode.

  According to the present invention, the addition of a photoacid generator to the alignment film composition allows the crosslinking reaction to proceed efficiently. Therefore, the alignment film and the optically anisotropic layer are provided with high adhesion, and the alignment film The saponification resistance of itself can be remarkably improved. In particular, according to the present invention, since it is possible to form an alignment film without elution into the saponification bath or film peeling during the saponification process during polarizing plate processing, by using this alignment film, productivity can be improved. An excellent polarizing plate can be produced.

  Furthermore, by using the optical film of the present invention, it becomes possible to optically compensate the liquid crystal cell with the same configuration as the conventional liquid crystal display device, and the liquid crystal display device of the present invention having the optical film comprises: Not only the display quality but also the viewing angle is remarkably improved.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  In the present invention, Re and Rth each represent a front retardation and a retardation in the thickness direction at a wavelength λ. Re is measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) by making light having a wavelength of λ nm incident in the normal direction of the film. Rth is Re and the slow axis in the plane (determined by KOBRA 21ADH) is used as the tilt axis (rotation axis), and the angle is changed with respect to the normal direction of the film. KOBRA 21ADH is calculated based on a plurality of retardation values measured in this manner.

  In this specification, “substantially” for the angle means that the error from the exact angle is within a range of less than ± 5 °. Furthermore, the error from the exact angle is preferably less than 4 °, more preferably less than 3 °. “Substantially equal” for retardation means that the retardation is within ± 10%. In addition, the measurement wavelength of the refractive index indicates an arbitrary wavelength in the visible light region unless otherwise specified. In the present specification, “visible light” means light having a wavelength of 400 to 700 nm.

[Optical film]
FIG. 1 is a schematic sectional view of an example of the optical film of the present invention. The optical film of the present invention has the optical anisotropic layer 12 on the transparent support 11 and functions as an optical film. Between the transparent support 11 and the optically anisotropic layer 12, an alignment film 13 for controlling the alignment of liquid crystalline molecules in the optically anisotropic layer 12 is disposed. The alignment film 13 is an alignment film composition (alignment film) containing at least a polymer having a reactive group in the side chain, a compound having an ethylenically unsaturated bond, a photoacid generator, and a solvent containing 20% by mass or more of water. A coating liquid for forming), and a layer formed by applying light and irradiating with light. If the optically anisotropic layer 12 is formed from a composition containing a liquid crystalline compound having a polymerizable group, the adhesion between the alignment film 13 and the optically anisotropic layer 12 can be improved, and washing with water, etc. Even during chemical treatment such as cleaning treatment or saponification treatment, peeling or the like hardly occurs, and the handleability is good. The optically anisotropic layer 12 can be produced by applying a coating solution prepared by dissolving a liquid crystalline compound in a solvent that can dissolve the liquid crystalline compound on the alignment film of the present invention to which the alignment property is imparted. Moreover, although it may be formed by vapor deposition if possible, it is preferably formed by coating. Application methods include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, wire bar method, etc. A well-known coating method is mentioned. Next, the solvent used at 25 ° C. to 130 ° C. is dried, and at the same time, the liquid crystalline compound is oriented, and further, if desired, fixed by ultraviolet irradiation or the like, thereby forming an optical anisotropic formed from the polymer of the liquid crystalline compound. A sex layer is obtained. The irradiation energy is preferably 20 mJ / cm ^{2 to} 50 J / cm ² , and more preferably 100 mJ / cm ^{2 to} 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. In order to accurately compensate a liquid crystal cell, particularly a VA mode liquid crystal cell, the optical properties of the optically anisotropic layer 12 are such that the front retardation (Re) is not 0 and the in-plane slow axis is inclined (rotated). The retardation value measured by making light of wavelength λ nm incident from a direction inclined + 40 ° with respect to the normal direction of the optical film as the axis), and the in-plane slow axis as the inclination axis (rotation axis) of the optical film It is preferable that the retardation values measured by making light having a wavelength λ nm incident from a direction inclined by −40 ° with respect to the normal direction are adjusted to be substantially equal. “Re is not 0” means that Re is not less than 5 nm.

[Polarizer]
2A to 2D are schematic cross-sectional views of a polarizing plate having the optical film of the present invention. In general, the polarizing plate can be prepared by dyeing a polarizing film made of a polyvinyl alcohol film with iodine and performing stretching to obtain the polarizing film 21, and laminating protective films 22 and 23 on both sides thereof. it can. Since the optical film of the present invention has a support made of a polymer film or the like that supports the optically anisotropic layer, this support can be used as it is for at least one of the protective films 22 and 23. At this time, even if the optically anisotropic layer 12 is arranged on the polarizing layer 21 side (that is, the optically anisotropic layer 12 is closer to the polarizing film 21 than the support 11), the optically anisotropic layer 12 is on the opposite side of the polarizing film 21 ( That is, the optically anisotropic layer 12 may be arranged farther from the support 11 than the polarizing film 21, but as shown in FIG. It is preferable that it exists in the other side. Further, as shown in FIG. 2 (b), it is also possible to bond to the outside of one protective film 22 of the polarizing layer 21 via an adhesive or the like.

  2C and 2D are configuration examples of a polarizing plate in which another functional layer 24 is arranged on the polarizing plate having the configuration shown in FIG. FIG. 2C is a configuration example in which another functional layer 24 is disposed on the protective film 23 disposed on the opposite side with the optical film of the present invention and the polarizing film 21 in between. ) Is a configuration example in which another functional layer 24 is disposed on the optical film of the present invention. Examples of other functional layers are not particularly limited, and examples thereof include functional layers that impart various characteristics, such as λ / 4 layers, antireflection layers, and hard coat layers. These layers may be bonded together with, for example, an adhesive as a member such as a λ / 4 plate, an antireflection film, or a hard coat film. In the configuration example of FIG. 2D, the optical film of the present invention. Another functional layer 24 can be formed on the (optically anisotropic layer 12) and then bonded to the polarizing layer 21. Further, the protective film 23 itself on the side opposite to the optical film of the present invention can be made into other functional films such as a λ / 4 plate, an antireflection film, and a hard coat film.

  When producing a polarizing plate by laminating a polarizing film and a protective film, a total of three films of a pair of protective film and polarizing film can be bonded together in a roll-to-roll manner. This roll-to-roll is a preferable method as a manufacturing process of a polarizing plate because it is difficult to cause dimensional change and curling of the polarizing plate as well as productivity, and can impart high mechanical stability.

[Liquid Crystal Display]
FIG. 3 shows an example of the liquid crystal display device of the present invention. The liquid crystal display device includes a liquid crystal cell 35 having a nematic liquid crystal sandwiched between upper and lower electrode substrates, and a pair of polarizing plates 36 and 37 disposed on both sides of the liquid crystal cell, and at least one of the polarizing plates. Uses the polarizing plate of the present invention shown in FIG. When using the polarizing plate of this invention, it can arrange | position so that an optically anisotropic layer may exist between a polarizing layer and the electrode substrate of a liquid crystal cell. The nematic liquid crystal molecules are controlled so as to be in a predetermined alignment state by providing an alignment film applied on the electrode substrate and a structure such as a rubbing process or a rib on the surface thereof.

  One or more light control films 34 such as a brightness enhancement film and a diffusion film may be provided below the liquid crystal cell sandwiched between the polarizing plates. Furthermore, the light control film has a reflection plate 32 and a light guide plate 33 for irradiating light emitted from the cold cathode tubes 31 to the front. Instead of a backlight unit comprising a cold cathode tube and a light guide plate, recently, a direct type backlight in which several cold cathode tubes are arranged under a liquid crystal cell, an LED backlight using an LED as a light source, or an organic EL Backlights that emit surface light using inorganic EL or the like are also used, but any of the optical films of the present invention is also effective in backlights.

  Further, although not shown in the figure, in the reflective liquid crystal display device, only one polarizing plate is required on the observation side, and a reflective film is provided on the back surface of the liquid crystal cell or on the inner surface of the lower substrate of the liquid crystal cell. . Of course, it is also possible to provide a front light using the light source on the liquid crystal cell observation side. Further, a transflective type in which a transmissive portion and a reflective portion are provided in one pixel of the display device is also possible.

Next, materials used for the production of the optical film of the present invention, production methods, and the like will be described in detail.
The optical film of the present invention has a transparent support, the alignment film, and the optically anisotropic layer, and the optically anisotropic layer expands the contrast viewing angle of the liquid crystal display device and colors the image of the liquid crystal display device. Contribute to eliminate. The optical film of the present invention has a configuration of a liquid crystal display device by the support of the optically anisotropic layer also serving as a protective film of a polarizing plate, or the optically anisotropic layer also serving as a protective film of a polarizing plate. The number of members can be reduced. In other words, this aspect contributes to the thinning of the liquid crystal display device.

  In the present invention, an optically anisotropic layer made of a liquid crystalline composition containing a liquid crystalline compound is formed on an optically uniaxial or biaxial transparent support made of a high molecular weight polymer, so that the optical property of the liquid crystal display device can be obtained. The characteristics can be remarkably improved.

[Optically Anisotropic Layer Consisting of Liquid Crystalline Composition]
The optical film of the present invention has an optically anisotropic layer formed from a liquid crystalline composition (a coating liquid for forming an optically anisotropic layer) containing a liquid crystalline compound. The optically anisotropic layer contributes to optically compensate the liquid crystal cell. Of course, the optically anisotropic layer alone may have sufficient optical compensation ability, or may be an aspect satisfying the optical characteristics required for optical compensation in combination with other layers (for example, a support). Liquid crystal compounds can be classified into rod-shaped and disc-shaped types based on their molecular shapes. In addition, there are low and high molecular types, respectively. Polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992). In the present invention, either a rod-like liquid crystal compound or a discotic liquid crystal compound can be used. Two or more kinds of rod-like liquid crystalline compounds, two or more kinds of discotic liquid crystalline compounds, or a mixture of a rod-like liquid crystalline compound and a discotic liquid crystalline compound may be used. The liquid crystal compound may have at least one polymerizable group. In the case of using a mixture, it is sufficient that at least one kind has a polymerizable group. The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, and more preferably 0.5 to 10 μm.

  Examples of the rod-like liquid crystal compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used. The polymer liquid crystalline compound is a polymer compound obtained by polymerizing a rod-like liquid crystalline compound having a low molecular polymerizable group. As the rod-like liquid crystalline compound having a low molecular polymerizable group that is particularly preferably used, a rod-like liquid crystalline compound represented by the following general formula (IV) can be exemplified.

Formula (IV): Q ¹ -L ¹ -A ¹ -L ³ -ML ⁴ -A ² -L ² -Q ²
Wherein, Q ¹ and Q ² each independently is a polymerizable group, L ^1, the L ^2, L ³ and L ⁴ each independently represent a single bond or a divalent linking group, L ³ and At least one of L ⁴ is preferably —O—CO—O—. A ¹ and A ² each independently represent a spacer group having 2 to 20 carbon atoms. M represents a mesogenic group.

Hereinafter, the rod-like liquid crystal compound having a polymerizable group represented by the general formula (IV) will be described in more detail. In the formula, Q ¹ and Q ² are each independently a polymerizable group. The polymerization reaction of the polymerizable group is preferably addition polymerization (including ring-opening polymerization) or condensation polymerization. In other words, the polymerizable group is preferably a polymerizable group capable of addition polymerization reaction or condensation polymerization reaction. Examples of polymerizable groups are shown below.

Examples of the divalent linking group represented by L ¹ , L ² , L ³ and L ⁴ include —O—, —S—, —CO—, —NR ² —, —CO—O—, and —O—CO. —O—, —CO—NR ² —, —NR ² —CO—, —O—CO—, —O—CO—NR ² —, —NR ² —CO—O—, and NR ² —CO—NR ^2. A divalent linking group selected from the group consisting of-is preferred. R ² is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom. In this case, it is preferable that at least one of L ³ and L ⁴ is —O—CO—O— (carbonate group). In the formula (IV), Q ¹ -L ¹ and Q ² -L ² -are CH ₂ ═CH—CO—O—, CH ₂ ═C (CH ₃ ) —CO—O—, and CH ₂ ═C ( Cl) -CO-O-CO- O- are _{preferable, CH 2 = CH-CO-} O- is most preferable.

A ¹ and A ² represent spacer groups having 2 to 20 carbon atoms. An aliphatic group having 2 to 12 carbon atoms is preferable, and an alkylene group is particularly preferable. The spacer group is preferably chain-like and may contain oxygen atoms or sulfur atoms that are not adjacent to each other. The spacer group may have a substituent and may be substituted with a halogen atom (fluorine, chlorine, bromine), a cyano group, a methyl group, or an ethyl group.

Examples of the mesogenic group represented by M include all known mesogenic groups. In particular, a group represented by the following general formula (V) is preferable.
Formula (V): - (- W 1 -L 5) n -W 2 -
In the formula, W ¹ and W ² each independently represent a divalent cycloaliphatic group, a divalent aromatic group or a divalent heterocyclic group, L ⁵ represents a single bond or a linking group, and Specific examples of the group include specific examples of the group represented by L ^{1 to} L ⁴ in the formula (IV), —CH ₂ —O—, and —O—CH ₂ —. n represents 1, 2 or 3.

W ¹ and W ² include 1,4-cyclohexanediyl, 1,4-phenylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 1,3,4-thiadiazole-2,5-diyl. 1,3,4-oxadiazole-2,5-diyl, naphthalene-2,6-diyl, naphthalene-1,5-diyl, thiophene-2,5-diyl, pyridazine-3,6-diyl It is done. In the case of 1,4-cyclohexanediyl, there are trans isomers and cis isomers, but either isomer may be used, and a mixture in any proportion may be used. More preferably, it is a trans form. W ¹ and W ² may each have a substituent. Examples of the substituent include a halogen atom (fluorine, chlorine, bromine, iodine), a cyano group, an alkyl group having 1 to 10 carbon atoms (methyl group, ethyl group, propyl group, etc.), and an alkoxy group having 1 to 10 carbon atoms. (Methoxy group, ethoxy group, etc.), C1-10 acyl group (formyl group, acetyl group, etc.), C1-10 alkoxycarbonyl group (methoxycarbonyl group, ethoxycarbonyl group, etc.), carbon atom Examples thereof include an acyloxy group having 1 to 10 (acetyloxy group, propionyloxy group, etc.), nitro group, trifluoromethyl group, difluoromethyl group and the like.

  Preferred examples of the basic skeleton of the mesogenic group represented by the general formula (V) are shown below. These may be substituted with the above substituents.

  Examples of the compound represented by the general formula (IV) are shown below, but the present invention is not limited thereto. The compound represented by the general formula (IV) can be synthesized, for example, by the method described in JP-T-11-513019.

  Discotic liquid crystal compounds that can be used in the present invention include various documents (C. Destrade et al., Mol. Cryst. Liq. Cryst., Vol. 71, page 111 (1981); edited by the Chemical Society of Japan, quarterly chemistry). Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); Zhang et al., J. Am.Chem.Soc., Vol.116, page 2655 (1994)). The polymerization of the discotic liquid crystal compound is described in JP-A-8-27284.

The discotic liquid crystal compound preferably has a polymerizable group so that it can be fixed by polymerization. For example, a structure in which a polymerizable group is bonded as a substituent to a discotic core of a discotic liquid crystal compound is conceivable. However, when a polymerizable group is directly connected to the discotic core, it is difficult to maintain the alignment state in the polymerization reaction. become. Therefore, a structure having a linking group between the discotic core and the polymerizable group is preferable. That is, the discotic liquid crystal compound having a polymerizable group is preferably a compound represented by the following general formula (VI).
Formula (VI): D (-LP) _n
In the formula, D is a discotic core, L is a divalent linking group, P is a polymerizable group, and n is an integer of 4 to 12.

  In the formula (VI), preferred specific examples of the discotic core (D), the divalent linking group (L) and the polymerizable group (P) are (D1 described in JP-A-2001-4837, respectively). ) To (D15), (L1) to (L25), (P1) to (P18), and the disk-shaped core (D), divalent linking group (L) and polymerizable group described in the publication The contents regarding (P) can be preferably applied here.

  In order to express biaxiality in the optically anisotropic layer, when using a rod-like liquid crystalline compound having a polymerizable group, a cholesteric alignment or a hybrid cholesteric alignment that is twisted while the inclination angle gradually changes in the thickness direction, It needs to be distorted by polarized light irradiation. Examples of the method of distorting the alignment by irradiation with polarized light include a method using a dichroic liquid crystalline polymerization initiator (International Publication WO03 / 054111) and a rod-like liquid crystalline compound having a photoalignable functional group such as a cinnamoyl group in the molecule. (Japanese Unexamined Patent Application Publication No. 2002-6138).

  When using a discotic liquid crystal compound having a polymerizable group, it may be fixed in any alignment state of horizontal alignment, vertical alignment, tilt alignment, and twist alignment, but has symmetry with respect to the normal direction of the film. Some horizontal alignment, vertical alignment, and twist alignment are preferable, and horizontal alignment is most preferable. Horizontal alignment means that the disc surface of the core of the discotic liquid crystalline compound and the horizontal surface of the transparent support are parallel, but it does not require that they be strictly parallel. An orientation with an inclination angle of less than 10 degrees is meant.

  The Re of the optically anisotropic layer is preferably 5 to 250 nm, more preferably 5 to 100 nm, and most preferably 10 to 80 nm. Rth is preferably 30 to 500 nm in total with Rth of the transparent support, more preferably 40 to 400 nm, and most preferably 100 to 350 nm.

  In the case of laminating two or more optically anisotropic layers, the combination of liquid crystal compounds is not particularly limited, and a laminate of all layers made of a discotic liquid crystal compound, a laminate of layers made of all a rod-like liquid crystal compound, a discotic It may be a laminate of a layer made of a liquid crystal compound and a layer made of a rod-like liquid crystal compound. The combination of the alignment states of the layers is not particularly limited, and optically anisotropic layers having the same alignment state may be stacked, or optically anisotropic layers having different alignment states may be stacked.

  The optically anisotropic layer comprises a liquid crystalline composition (coating liquid for forming an optically anisotropic layer) containing the liquid crystalline compound and, if desired, the following polymerization initiator and other additives on an alignment film. It can be formed by coating. As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination. The coating liquid can be applied by a known method (eg, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

[Fixation of alignment state of liquid crystalline compounds]
It is preferable to fix the aligned liquid crystal compound molecules while maintaining the alignment state. The immobilization is preferably carried out by a polymerization reaction of a polymerizable group introduced into the liquid crystal compound. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator, and a photopolymerization reaction is more preferable. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. Group acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US patents) No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970).

The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the coating solution. Light irradiation for the polymerization of the liquid crystalline compound is preferably performed using ultraviolet rays. The irradiation energy is preferably ^{20mJ / cm 2 ~10J / cm 2} , further preferably 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

[Optical alignment by polarized irradiation]
The optically anisotropic layer of the present invention can generate in-plane retardation by irradiation with polarized light as necessary. This polarized light irradiation may be performed at the same time as the photopolymerization process in the above-mentioned orientation fixing, or may be further fixed by non-polarized light after first polarized light irradiation, or fixed first by non-polarized light irradiation. The irradiation with polarized light may be performed after conversion. In order to obtain a large retardation, it is preferable to irradiate polarized light alone or first. The polarized light irradiation is preferably performed in an inert gas atmosphere having an oxygen concentration of 3% or less, more preferably 0.5% or less. As polarized light irradiation, ultraviolet polarized light irradiation is preferable, polarized light irradiation having a peak at 365 ± 10 nm is particularly preferable, and polarized light irradiation having a peak at 365 ± 5 nm is more preferable. The irradiation energy is preferably ^{20mJ / cm 2 ~10J / cm 2} , further preferably 100 to 800 mJ / cm ^2. The illuminance is preferably 20 to 1000 mW / cm ^2, more preferably 50 to 500 mW / cm ^2, further preferably 100 to 350 mW / cm ^2. Although there is no restriction | limiting in particular about the kind of liquid crystalline compound hardened | cured by polarized light irradiation, The liquid crystalline compound which has an ethylenically unsaturated group as a polymeric group is preferable.
Note that an optically anisotropic layer exhibiting in-plane retardation generated by photo-alignment by polarized light irradiation is particularly excellent in the function of optically compensating a VA mode liquid crystal display device.

[Horizontal alignment agent]
The liquid crystalline compound forming the optically anisotropic layer can be substantially horizontally aligned by using at least one of the compounds represented by the following general formulas (VII) to (IX). In the present invention, “horizontal alignment” means that in the case of a rod-like liquid crystalline compound, the molecular long axis and the horizontal plane of the transparent support are parallel, and in the case of a discotic liquid crystalline compound, the discotic liquid crystalline compound This means that the disk surface of the core and the horizontal surface of the transparent support are parallel to each other, but it is not required to be strictly parallel. In this specification, the orientation of the inclination angle with the horizontal surface is less than 10 degrees. Shall mean. The inclination angle is preferably 0 to 5 degrees, more preferably 0 to 3 degrees, further preferably 0 to 2 degrees, and most preferably 0 to 1 degree.

  In the present invention, the amount of the compound represented by the general formulas (VII) to (IX) is preferably 0.01 to 20% by mass, and 0.01 to 10% by mass of the amount of the liquid crystal compound. More preferably, 0.02-1 mass% is especially preferable. In addition, the compounds represented by the general formulas (VII) to (IX) may be used alone or in combination of two or more.

  Hereinafter, the following general formulas (VII) to (IX) will be described in order.

In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or a substituent, and X ¹ , X ² and X ^{3 each} represent a single bond or a divalent linking group. The substituent represented by each of R ^{1 to} R ³ is preferably a substituted or unsubstituted alkyl group (more preferably an unsubstituted alkyl group or a fluorine-substituted alkyl group), an aryl group (particularly a fluorine-substituted alkyl). An aryl group having a group is preferred), a substituted or unsubstituted amino group, an alkoxy group, an alkylthio group, and a halogen atom. The divalent linking groups represented by X ¹ , X ² and X ³ are each an alkylene group, an alkenylene group, a divalent aromatic group, a divalent heterocyclic residue, —CO—, —NR ^a — ( R ^a is ^a divalent linking group selected from the group consisting of an alkyl group having 1 to 5 carbon atoms or a hydrogen atom), —O—, —S—, —SO—, —SO ₂ —, and combinations thereof. Preferably there is. The divalent linking group is selected from the group consisting of an alkylene group, a phenylene group, —CO—, —NR ^a —, —O—, —S—, and SO ₂ — or the group. It is more preferably a divalent linking group in which at least two groups are combined. The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The number of carbon atoms of the divalent aromatic group is preferably 6-10.

In the formula, R represents a substituent, and m represents an integer of 0 to 5. When m represents an integer greater than or equal to 2, several R may be same or different. Preferred substituents for R are the same as those recited as preferred ranges for the substituents represented by R ¹ , R ² , and R ³ in formula (VII). m preferably represents an integer of 1 to 3, particularly preferably 2 or 3.

In the formula, R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ each independently represent a hydrogen atom or a substituent. The substituents represented by R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ are preferably the substituents represented by R ¹ , R ² and R ³ in the general formula (VII). It is listed as a thing.

[Alignment film composition, alignment film]
The alignment film composition of the present invention is an alignment film composition (alignment film formation) used for production of an optical film having an optically anisotropic layer comprising a liquid crystalline composition containing a support, an alignment film, and a liquid crystalline compound. Coating solution), comprising at least a polymer having a reactive group in the side chain, a compound having an ethylenically unsaturated bond, a photoacid generator, and a solvent containing 20% by mass or more of water. The alignment film composition.
After forming the coating film by applying and drying the alignment film composition of the present invention on the support, the reactive film possessed by the polymer contained in the composition is irradiated with light such as ultraviolet rays. Is cured by crosslinking with a compound having an ethylenically unsaturated bond. Generally, before or after such a curing reaction (crosslinking reaction), the alignment film is subjected to a rubbing treatment. The rubbing treatment is performed, for example, by rubbing the surface of the polymer layer several times with paper or cloth in a certain direction. Then, an optical film having an optically anisotropic layer is formed on the alignment film by applying and drying a liquid crystalline composition (a coating liquid for forming an optically anisotropic layer) on the alignment film after the rubbing treatment. . Thus, an alignment film formed from a polymer having a reactive group in the side chain and a compound having an ethylenically unsaturated bond is excellent in adhesion to the optically anisotropic layer formed thereon. However, if the progress of the crosslinking reaction is insufficient, when the optical film is subjected to a saponification treatment in the polarizing plate production process, elution or peeling to the saponification bath occurs, which hinders stable production of the polarizing plate. There is a fear. On the other hand, in this invention, the above-mentioned crosslinking reaction can be advanced with high efficiency by adding a photo-acid generator to alignment film composition. Thereby, it is possible to form an optical film suitable for application to a polarizing plate, which is excellent in adhesion between the alignment film and the optically anisotropic layer and is suppressed from elution and peeling during the saponification treatment.

The alignment film is provided on the transparent support and has a function of defining the alignment direction of the liquid crystalline compound provided thereon by coating or the like. In the present invention, the alignment film is added with a compound having an ethylenically unsaturated bond, specifically a monomer or oligomer having an ethylenically unsaturated bond, and a photoacid generator that have been subjected to an alignment process such as a rubbing process. The polymer film is a polymer having a reactive group in the side chain. The polymer can have groups having vinyl, oxirane, aziridinyl or allyl. The polymer is preferably at least one selected from polyvinyl alcohol or modified polyvinyl alcohol (polyvinyl alcohol derivative) having a polymerizable group in the side chain, a poly (meth) acrylate derivative, and a polysaccharide. In polyvinyl alcohol, at least one hydroxyl group can be replaced with a group having a vinyl moiety, an oxirane moiety or an aziridinyl moiety. In general, the above-mentioned moiety is composed of a polymer chain (carbon atom) of polyvinyl alcohol, an ether bond (—O—), a urethane bond (—OCONH—), an acetal bond ((—O—) ₂ CH—) or an ester bond (— OCO-). A urethane bond, an acetal bond or an ester bond is preferred. Vinyl, oxirane, aziridinyl or aryl is preferably bonded indirectly to polyvinyl alcohol via the above bond, that is, the group having the above moiety is preferably bonded to polyvinyl alcohol together with the bonding group. .

  By reacting a compound having a group to be introduced into polyvinyl alcohol or modified polyvinyl alcohol with polyvinyl alcohol, polyvinyl alcohol having a specific group can be obtained. Polyvinyl alcohol or modified polyvinyl alcohol generally has a saponification degree of 70 to 100%. The polymerization degree is preferably in the range of 100 to 3000. The saponification degree is preferably in the range of 80 to 100%, particularly preferably 85 to 95%. Moreover, as a polymerization degree, the range of 100-3000 is preferable. Examples of polyvinyl alcohol or modified polyvinyl alcohol preferably used in the present invention are described in JP-A-9-152509.

  Examples of the polysaccharide include polysaccharides such as cellulose, pullulan and starch, hydroxyalkylated polysaccharides such as hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl starch and hydroxypropyl pullulan, dihydroxypropyl cellulose, dihydroxypropyl pullulan and dihydroxypropyl starch. And dihydroxyalkylated polysaccharides. Details of the alignment film of polysaccharides are described in, for example, JP-A-6-230388. Examples of the poly (meth) acrylate include poly (meth) acrylamide, poly (meth) acrylic acid and salts thereof, poly (meth) acrylic acid ester, and derivatives and copolymers thereof.

[Compound having an ethylenically unsaturated bond]
The alignment film composition includes a compound having an ethylenically unsaturated bond. The compound is preferably a monomer or oligomer having at least one ethylenically unsaturated bond and at least one polymerizable group. For example, when the alignment film composition of the present invention is prepared, the compound is dissolved in a solvent together with the polymer and applied to the support surface. The compound efficiently crosslinks a polymer having a functional group (for example, a hydroxyl group when the alignment film is mainly composed of polyvinyl alcohol or a derivative thereof) by irradiation with ultraviolet rays or the like in the presence of a photoacid generator described later. Thus, the curing of the alignment film is promoted. On top of that, an optically anisotropic layer is applied, and the compound having a polymerizable group and a liquid crystalline compound having a polymerizable group are polymerized by irradiation with ultraviolet rays or the like to form an optically anisotropic layer. The adhesion between the alignment film and the optically anisotropic layer can be further enhanced. Therefore, the compound having an ethylenically unsaturated bond preferably has a substituent having an affinity for the functional group of the polymer constituting the alignment film.

  Examples of the compound having an ethylenically unsaturated bond include trimethoxyvinylsilane, diethoxymethylvinylsilane, diethoxydivinylsilane, triethoxyvinylsilane, allyltriethoxysilane, 3-allylthiopropyltrimethoxysilane, 3 -Allylaminopropyltrimethoxysilane, 3- (meth) acryloxypropyldimethoxymethylsilane, 3- (meth) acryloxypropyltrimethoxysilane, 2-methacryloyloxyethyl isocyanate (Karenz MOI), p-styryltrimethoxysilane , Glycidyl methacrylate and the like are preferable, and 3-acryloxypropyltrimethoxysilane is particularly preferable.

[Photoacid generator]
The alignment film composition of the present invention contains a photoacid generator. A photoacid generator is a compound that generates an acid upon irradiation with light such as ultraviolet rays. The photoacid generator can efficiently advance cross-linking between a polymer having a reactive group in the side chain and a compound having an ethylenically unsaturated bond, whereby an alignment film and an optically anisotropic layer It is possible to obtain the effect of improving the adhesion to the resin and the effect of suppressing elution and peeling during the saponification treatment.

  As the photoacid generator used in the alignment film, a water-soluble photoacid generator is preferably used, and an iodonium salt or a sulfonium salt is particularly preferably used. Preferable examples of the iodonium salt or the sulfonium salt include salts represented by the following general formula.

In the formula, R is H, an alkyl group having 1 to 6 carbon atoms, or a branched alkyl group. X- represents a counter ion of an iodonium salt or a sulfonium salt. Preferably PF ₆ ^- or CF ₃ SO ₃ ^- is.

Preferred specific examples include diphenyliodonium hexafluorophosphate, bis (4-tert-butylphenyl) iodonium oxafluorophosphate, bis (4-tert-butylphenyl) iodonium oxafluorophosphate, tris (4-methylphenyl) ) Sulfonium trifluoromethanesulfonate, tris (4-methylphenyl) sulfonium hexafluorophosphate, and the like. Among them, diphenyliodonium hexafluorophosphate is particularly preferable. By irradiating the alignment film coated on the transparent support with ultraviolet rays or the like, the photoacid generator is decomposed and acid is released. As a result, the cross-linking reaction between the monomer having an ethylenically unsaturated bond and the polymer can be promoted with high efficiency, and the adhesion between the alignment film and the optically anisotropic layer is improved, and elution during the saponification treatment is performed. And peeling can be suppressed. The crosslinking reaction can be carried out by irradiating the coating film with light such as ultraviolet rays or electron beams before or after the rubbing treatment. The light irradiation conditions can be appropriately set according to the composition of the alignment film composition, etc., but non-polarized ultraviolet irradiation with an illuminance of 50 to 200 mW / cm ² and an irradiation energy of 10 to 100 mJ / cm ² is particularly preferably used. The

  The solvent contained in the alignment film composition contains 20% by mass or more, preferably 50-80% by mass of water. By using it as a hydrous solvent, elution of the support by the solvent can be suppressed or controlled when it is applied on the support.

  The content of each component in the alignment film composition can be appropriately set so that a stable alignment film can be formed. For example, the content of the polymer having a reactive group in the side chain is 2.0 to 10.0% by mass, preferably 3.5 to 5.0% by mass, based on the total amount of the composition. it can. Moreover, content of the compound containing an ethylenically unsaturated bond can be set according to the said high molecular weight, for example, 1.0-15.0 mass% with respect to high molecular weight, Preferably it is 3.0. It can be set to -10.0 mass%. The addition amount of the photoacid generator can be appropriately set within a range in which the above-described crosslinking reaction can be promoted with high efficiency, and is, for example, 1.0 to 15.0 mass%, preferably 3. It can be set to 0-10.0 mass%. Moreover, the solvent amount in a composition can be 80-98 mass% with respect to the total amount of a composition, for example, Preferably it can be 90-97 mass%.

[Support]
As the support for the optically anisotropic layer, it is preferable to use a polymer film having a light transmittance of 80% or more. The thickness of the support is preferably 10 to 500 μm, more preferably 20 to 200 μm, and most preferably 35 to 110 μm.

  The glass transition temperature (Tg) of the transparent support used in the present invention is appropriately determined according to the purpose of use. The glass transition temperature of the resin is preferably 70 ° C. or higher, more preferably 75 ° C. to 200 ° C., and particularly preferably 80 ° C. to 180 ° C. When a resin in this range is employed, heat resistance and molding processability are highly balanced, which is preferable.

  The Re of the transparent support is preferably adjusted to a range of −200 to 100 nm, and Rth is preferably adjusted to a range of −100 to 100 nm. Re is more preferably −50 to 30 nm, and most preferably −30 to 20 nm. In the present specification, negative Re means that the in-plane slow axis of the transparent support is in the TD direction (direction orthogonal to the film transport direction), and negative Rth is the in-plane average refractive index in the thickness direction. It means bigger than.

  Examples of the polymer constituting the transparent support include cellulose ester (eg, cellulose acetate, cellulose propionate, cellulose butyrate), polyolefin (eg, norbornene-based polymer), poly (meth) acrylic acid ester (eg, poly Methyl methacrylate), polycarbonate, polyester and polysulfone. Commercially available polymers (for norbornene polymers, Arton (manufactured by JSR), Zeonore (manufactured by Nippon Zeon), etc.) may be used.

  In particular, when used as a protective film for a polarizing plate, a cellulose ester is preferable, and a lower fatty acid ester of cellulose is more preferable. Lower fatty acid means a fatty acid having 6 or less carbon atoms. The number of carbon atoms is preferably 2 (cellulose acetate), 3 (cellulose propionate) or 4 (cellulose butyrate). Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may be used. Of the lower fatty acid esters of cellulose, cellulose acetate is most preferred. The acyl group substitution degree of the cellulose ester is preferably 2.50 to 3.00, more preferably 2.75 to 2.95, and most preferably 2.80 to 2.90.

  The viscosity average polymerization degree (DP) of the cellulose ester is preferably 250 or more, and more preferably 290 or more. In addition, the cellulose ester preferably has a narrow molecular weight distribution of Mm / Mn (Mm is a mass average molecular weight, Mn is a number average molecular weight) by gel permeation chromatography. The value of Mm / Mn is preferably 1.0 to 5.0, more preferably 1.3 to 3.0, and most preferably 1.4 to 2.0.

  In the cellulose ester, the hydroxyl groups at the 2-position, 3-position and 6-position of cellulose are not evenly substituted but the degree of substitution at the 6-position tends to be small. In the present invention, the 6-position substitution degree of the cellulose ester is preferably about the same as or higher than the 2-position and 3-position. The ratio of the 6-position substitution degree to the total of the 2-position, 3-position and 6-position substitution degrees is preferably 30 to 40%. The ratio of the 6-position substitution degree is preferably 31% or more, particularly preferably 32% or more. The substitution degree at the 6-position is preferably 0.88 or more. The 6-position of cellulose may be substituted with an acyl group having 3 or more carbon atoms (eg, propionyl, butyryl, valeroyl, benzoyl, acryloyl) in addition to acetyl. The degree of substitution at each position can be measured by NMR. Cellulose esters having a high degree of substitution at the 6-position are described in Synthesis Example 1 described in Paragraph Nos. 0043 to 0044, Synthesis Example 2 described in Paragraph Nos. 0048 to 0049, and Paragraph Nos. 0051 to 0052. It can synthesize | combine with reference to the synthesis example 3 of these.

  A plasticizer can be added to the cellulose ester film in order to improve mechanical properties or increase the drying speed. As the plasticizer, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP), biphenyl diphenyl phosphate, and tricresyl phosphate (TCP). Representative examples of the carboxylic acid ester include phthalic acid esters and citric acid esters. Examples of phthalic acid esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethyl hexyl phthalate (DEHP). Examples of citrate esters include triethyl O-acetylcitrate (OACTE) and tributyl O-acetylcitrate (OACTB). Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters. Phthalate plasticizers (DMP, DEP, DBP, DOP, DPP, DEHP) are preferably used. DEP and DPP are particularly preferred. The addition amount of the plasticizer is preferably 0.1 to 25% by mass of the amount of cellulose ester, more preferably 1 to 20% by mass, and most preferably 3 to 15% by mass.

  A degradation inhibitor (eg, antioxidant, peroxide decomposer, radical inhibitor, metal deactivator, acid scavenger, amine) may be added to the cellulose ester film. The deterioration preventing agents are described in JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, and JP-A-6-107854. The addition amount of the deterioration preventing agent is preferably 0.01 to 1% by mass of the solution (dope) to be prepared, and more preferably 0.01 to 0.2% by mass. When the addition amount is less than 0.01% by mass, the effect of the deterioration preventing agent is hardly recognized. When the addition amount exceeds 1% by mass, bleed-out (bleeding) of the deterioration preventing agent to the film surface may be observed. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BHT) and tribenzylamine (TBA). Furthermore, a very small amount of dye may be added to prevent light piping. From the viewpoint of transmittance, it is preferable to adjust the type and amount so that the transmittance of light having a wavelength of 420 nm is 50% or more. The added amount of the dye is preferably 0.01 ppm to 1 ppm.

  In order to control the Re retardation value and the Rth retardation value, a retardation control agent can be added to the cellulose ester film. The retardation control agent is preferably used in the range of 0.01 to 20 parts by mass, more preferably 0.05 to 15 parts by mass, with respect to 100 parts by mass of the cellulose ester. Most preferably, it is used in the range of 1 to 10 parts by mass. Two or more retardation control agents may be used in combination. The retardation control agent is described in the pamphlets of International Publication No. WO01 / 88574 and International Publication No. WO00 / 2619, and Japanese Unexamined Patent Publication Nos. 2000-1111914 and 2000-275434.

  The cellulose ester film can be produced by a solvent cast method using a solution containing cellulose ester and other components as a dope. The dope can be cast on a drum or band and the solvent evaporated to form a film. It is preferable to adjust the concentration of the dope before casting so that the solid content is 10 to 40% by mass. The solid content is more preferably 18 to 35% by mass. Two or more dopes can be cast. The surface of the drum or band is preferably finished in a mirror state. The casting and drying methods in the solvent casting method are described in U.S. Pat. No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-115035.

  The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. Then, the method can be employed in which the obtained film is peeled off from the drum or band and further dried with high-temperature air at different temperatures of 100 to 160 ° C. to evaporate the residual solvent (described in Japanese Patent Publication No. 5-17844). . According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting. When casting a plurality of cellulose ester solutions, a solution is prepared by casting a solution containing cellulose ester from a plurality of casting openings provided at intervals in the traveling direction of the support, and laminating them. (Japanese Patent Laid-Open Nos. 61-158414, 1-122419, and 11-198285). A film can also be produced by casting a cellulose ester solution from two casting ports (Japanese Patent Publication Nos. 60-27562, 61-94724, 61-947245, 61-104413, No. 61-158413 and JP-A-6-134933). Employs a method of casting a cellulose ester film (described in JP-A-56-162617) by wrapping a flow of a high-viscosity cellulose ester solution with a low-viscosity cellulose ester solution and simultaneously extruding the high-viscosity and low-viscosity cellulose ester solutions. May be.

  The retardation of the cellulose ester film can be further adjusted by a stretching treatment. The draw ratio is preferably in the range of 3 to 100%. Tenter stretching is preferred. In order to control the slow axis with high accuracy, it is preferable to make the difference between the left and right tenter clip speeds and the separation timing as small as possible. The stretching process is described on page 37, line 8 to page 38, line 8 of WO 01/88574.

  The cellulose ester film can be subjected to a surface treatment. Examples of the surface treatment include corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment, and ultraviolet irradiation treatment. From the viewpoint of maintaining the flatness of the film, the temperature of the cellulose ester film in the surface treatment is preferably Tg (glass transition temperature) or lower, specifically 150 ° C. or lower.

  The thickness of the cellulose ester film can be adjusted by lip flow rate and line speed, or stretching or compression when it is produced by film formation. Since the moisture permeability varies depending on the main material to be used, it is possible to adjust the thickness to a preferable moisture permeability range as a protective film for the polarizing plate. Moreover, the free volume of the said cellulose-ester film can be adjusted with drying temperature and time, when producing by film forming. Also in this case, since the moisture permeability varies depending on the main material used, it is possible to make the moisture permeability range preferable as a protective film by adjusting the free volume. The hydrophilicity / hydrophobicity of the cellulose ester film can be adjusted by an additive. Moisture permeability is increased by adding a hydrophilic additive in the free volume, and conversely, moisture permeability can be lowered by adding a hydrophobic additive. Thus, by adjusting the moisture permeability of the cellulose ester film by various methods, it is possible to obtain a range of moisture permeability preferable as a protective film for the polarizing plate, and the support of the optically anisotropic layer is protected for the polarizing plate. A polarizing plate that can also serve as a film and has an optical compensation capability can be manufactured at low cost with high productivity.

  The alignment film of the present invention comprises a step of coating and drying the alignment film composition on a support to form a coating film, a step of irradiating the coating film with light, and a step of rubbing the coating film irradiated with light. In the above order or by applying and drying the alignment film composition on a support to form a coating film, rubbing the coating film, and applying light to the rubbed coating film. It can manufacture with the manufacturing method which has the process to irradiate in this order. The details of the manufacturing method are as described above.

[Optical film]
The optical film of the present invention is an optical film having an optically anisotropic layer made of a liquid crystalline composition containing a support, an alignment film, and a liquid crystal compound, and the alignment film is the alignment film of the present invention described above. And the optically anisotropic layer is formed from a polymer of the liquid crystalline compound. The optical film of this invention can be used for a liquid crystal display device with the aspect described below, for example. However, the present invention is not limited to this embodiment.

[Polarizer]
The polarizing plate of the present invention is a polarizing plate having the optical film and a polarizing film. A polarizing plate used in a liquid crystal display device includes a polarizing film and a pair of protective films that sandwich the polarizing film. Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine polarizing film and the dye polarizing film are generally produced using a polyvinyl alcohol film. The kind of protective film is not particularly limited, and cellulose esters such as cellulose acetate, cellulose acetate butyrate, and cellulose propionate, polycarbonate, polyolefin, polystyrene, polyester, and the like can be used. The transparent protective film is usually supplied in a roll form, and it is preferable that the transparent protective film is continuously bonded to the long polarizing film so that the longitudinal directions thereof coincide. Here, the orientation axis (slow axis) of the protective film may be any direction. Further, the angle between the slow axis (alignment axis) of the protective film and the absorption axis (stretching axis) of the polarizing film is not particularly limited, and can be appropriately set according to the purpose of the polarizing plate.

The polarizing film and the protective film may be bonded together with an aqueous adhesive. The adhesive solvent in the water-based adhesive is dried by diffusing in the protective film. The higher the moisture permeability of the protective film, the faster the drying and the higher the productivity. However, if the protective film is too high, the moisture will enter the polarizing film due to the usage environment (high humidity) of the liquid crystal display device. The performance drops. The moisture permeability of the optical film is determined by the thickness, free volume, hydrophilicity / hydrophobicity, etc. of the polymer film (and polymerizable liquid crystal compound). The moisture permeability of the protective film for the polarizing plate is preferably in the range of 100 to 1000 (g / m ² ) / 24 hrs, and more preferably in the range of 300 to 700 (g / m ² ) / 24 hrs.

  In the present invention, for the purpose of reducing the thickness, one of the protective films of the polarizing film may also serve as the support for the optically anisotropic layer, or the optically anisotropic layer itself. The optically anisotropic layer and the polarizing film are preferably subjected to a fixing treatment from the viewpoint of preventing displacement of the optical axis and preventing entry of foreign matters such as dust. An appropriate method such as an adhesive method through a transparent adhesive layer can be applied to the fixed lamination. There is no particular limitation on the type of the adhesive and the like, and from the viewpoint of preventing changes in the optical properties of the constituent members, those that do not require a high-temperature process during curing or drying are preferable, and a long-time curing process is preferable. And those that do not require drying time. From such a viewpoint, a hydrophilic polymer adhesive or a pressure-sensitive adhesive layer is preferably used.

  Appropriate functional layers such as a protective film for various purposes such as water resistance according to the above protective film, an antireflection layer and / or an antiglare treatment layer for the purpose of preventing surface reflection, etc. on one or both sides of the polarizing film You may use the polarizing plate which formed. The antireflection layer can be suitably formed, for example, as a light interference film such as a fluorine polymer coating layer or a multilayer metal vapor deposition film. The antiglare layer is also formed by an appropriate method that diffuses the surface reflected light, for example, by providing a fine uneven structure on the surface by an appropriate method such as a resin coating layer containing fine particles, embossing, sandblasting or etching. can do.

  Examples of the fine particles include inorganic materials such as silica, calcium oxide, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle size of 0.5 to 20 μm. One kind or two or more kinds of fine particles, cross-linked or non-cross-linked organic fine particles made of a suitable polymer such as polymethyl methacrylate and polyureta can be used. The above-mentioned adhesive layer or pressure-sensitive adhesive layer may contain such fine particles and exhibit light diffusibility.

  The polarizing plate of the present invention preferably has optical properties and durability (storability in short and long term) equivalent to or higher than those of commercially available super high contrast products (for example, HLC2-5618 manufactured by Sanlitz Co., Ltd.). . Specifically, the visible light transmittance is 42.5% or more, and the degree of polarization √ {(Tp−Tc) / (Tp + Tc)} ≧ 0.9995 (where Tp is parallel transmittance and Tc is orthogonal transmittance) The change rate of the light transmittance before and after being left for 500 hours in a 60 ° C. and 90% humidity RH atmosphere and for 500 hours in a 80 ° C. dry atmosphere is 3% or less based on the absolute value. Is preferably 1% or less, and the rate of change in polarization degree is preferably 1% or less, more preferably 0.1% or less, based on the absolute value.

  The display mode of the liquid crystal display device used in the present invention is not particularly limited, but will be described by taking the VA mode as an example. Note that the liquid crystal display device used in the present invention is effective not only in the display mode but also in an aspect applied to the STN mode, the TN mode, and the OCB mode.

[VA mode liquid crystal cell]
In the present invention, the liquid crystal cell is preferably in a vertically aligned mode (VA mode). The VA mode liquid crystal cell is formed by sealing liquid crystal molecules having negative dielectric anisotropy between upper and lower substrates whose opposite surfaces are rubbed. For example, by using liquid crystal molecules having Δn = 0.0813 and Δε = −4.6, a director indicating the alignment direction of the liquid crystal molecules, that is, a liquid crystal cell having a so-called tilt angle of about 89 ° can be manufactured. At this time, the thickness d of the liquid crystal layer can be about 3.5 μm. The brightness at the time of white display changes depending on the magnitude of the product Δn · d of the thickness d (nm) of the liquid crystal layer and the refractive index anisotropy Δn. In order to obtain the maximum brightness, the thickness d of the liquid crystal layer is preferably in the range of 2 to 5 μm (2000 to 5000 nm), and Δn is in the range of 0.060 to 0.085.

  As shown in FIG. 3, transparent electrodes are formed inside the upper and lower substrates of the liquid crystal cell 35, but in a non-driving state in which no driving voltage is applied to the electrodes, the liquid crystal molecules in the liquid crystal layer are roughly with respect to the substrate surface. As a result, the polarization state of light passing through the liquid crystal panel is hardly changed. Since the absorption axis of the upper polarizing plate 37 of the liquid crystal cell and the absorption axis of the lower polarizing plate 36 are substantially orthogonal, light does not pass through the polarizing plate. In other words, in the VA mode liquid crystal display device, an ideal black display can be realized in the non-driven state. On the other hand, in the driving state, the liquid crystal molecules are inclined in a direction parallel to the substrate surface, and the light passing through the liquid crystal panel changes the polarization state by the inclined liquid crystal molecules and passes through the polarizing plate.

  Up to this point, since an electric field is applied between the upper and lower substrates, an example using a liquid crystal material having a negative dielectric anisotropy in which liquid crystal molecules respond perpendicularly to the electric field direction has been shown. In the case where the liquid crystal material is disposed on the substrate and an electric field is applied in a lateral direction parallel to the substrate surface, a liquid crystal material having a positive dielectric anisotropy can be used.

  The characteristics of the VA mode are fast response and high contrast. However, there is a problem that the contrast is high in the front but decreases in the oblique direction. Since the liquid crystal molecules are aligned perpendicular to the substrate surface during black display, when viewed from the front, there is almost no birefringence of the liquid crystal molecules, so the transmittance is low and high contrast can be obtained. However, when observed obliquely, birefringence occurs in the liquid crystalline molecules. Furthermore, the crossing angle of the upper and lower polarizing plate absorption axes is 90 ° perpendicular to the front, but is greater than 90 ° when viewed from an oblique direction. Due to these two factors, leakage light tends to occur in the oblique direction, and the contrast tends to decrease. In the present invention, this problem can be solved by providing at least one optically anisotropic layer on a transparent support having predetermined optical properties.

  In the VA mode, liquid crystal molecules are tilted during white display, but the birefringence of the liquid crystal molecules when viewed from an oblique direction is different between the tilt direction and the opposite direction, resulting in differences in luminance and color tone. . In order to solve this, the liquid crystal cell is preferably multi-domain. Multi-domain refers to a structure in which a plurality of regions having different alignment states are formed in one pixel. For example, in a multi-domain VA mode liquid crystal cell, a plurality of regions in which tilt angles of liquid crystal molecules are different from each other when an electric field is applied exist in one pixel. In a multi-domain VA mode liquid crystal cell, the tilt angle of liquid crystal molecules due to application of an electric field can be averaged for each pixel, whereby the viewing angle characteristics can be averaged. Dividing the orientation within one pixel can be achieved by providing a slit in the electrode, providing a protrusion, changing the direction of the electric field, or biasing the electric field density. In order to obtain a uniform viewing angle in all directions, the number of divisions may be increased. However, since the transmittance during white display is reduced, four divisions are preferable.

  In a VA mode liquid crystal display device, the addition of a chiral agent generally used in a Twisted Nematic mode (TN mode) liquid crystal display device is rarely used to degrade the dynamic response characteristics. Sometimes added to reduce. At the boundary of the alignment division, the liquid crystal molecules are difficult to respond. For this reason, in normally black display, since black display is maintained, a reduction in luminance becomes a problem. Adding a chiral agent to the liquid crystal material contributes to reducing the boundary region. In particular, in the present invention, it is preferable to use a rod-like liquid crystalline compound and a chiral agent in combination. As the chiral agent, a known agent can be used.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

(Preparation of transparent support S-1)
A commercial cellulose acetate film, Fujitac TD80UF (Fuji Photo Film Co., Ltd., Re = 3 nm, Rth = 50 nm) was used as the transparent support S-1.

(Preparation of transparent support S-2)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.
──────────────────────────────────────
Cellulose acetate solution composition (mass%) Inner layer Outer layer ──────────────────────────────────────
Cellulose acetate with an acetylation degree of 60.9% 20.89 19.78
Triphenyl phosphate (plasticizer) 1.63 1.54
Biphenyl diphenyl phosphate (plasticizer) 0.815 0.770
Methylene chloride (first solvent) 61.22 62.12
Methanol (second solvent) 14.83 15.03
1-butanol (third solvent) 0.313 0.320
Silica (particle size 20 nm) 0.00 0.160
Retardation increasing agent S-2-1 0.302 0.280
──────────────────────────────────────

  The obtained inner layer dope and outer layer dope were cast on a drum cooled to 0 ° C. using a three-layer co-casting die. The film with a residual solvent amount of 70% by mass is peeled off from the drum, both ends are fixed with a pin tenter and dried at 80 ° C. while being conveyed with a draw ratio in the conveying direction of 110%, and the residual solvent amount is 10% by mass. Then, it was dried at 110 ° C. Thereafter, a cellulose acetate film (outer layer: 3 μm, inner layer: 74 μm, outer layer: 3 μm) having a residual solvent of 0.3% by mass produced by drying at 140 ° C. for 30 minutes was used as the transparent support S-2. The optical properties of the obtained film were Re = 8 nm and Rth = 82 nm.

(Preparation of transparent support S-3)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acylate solution.
──────────────────────────────────────
Cellulose acylate solution composition (mass%)
──────────────────────────────────────
Cellulose acylate (substitution degree of acetate group 1.2, butyryl group 1.3)
24.0
Mixed solvent (table below) 75.0
Retardation increasing agent S-3-1 0.70
2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine (UV agent a) 0.12
2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole (UV agent b) 0.05
2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5-chlorobenzotriazole (UV agent c) 0.02
Silica (972, manufactured by Nippon Aerosil Co., Ltd.) 0.06
Citric acid ethyl ester (1: 1 mixture of monoester and diester) 0.05
──────────────────────────────────────

─────────────────────────────────────
Mixed solvent composition (mass%)
─────────────────────────────────────
Methyl acetate 80.0
Acetone 5.0
Methanol 7.0
Ethanol 5.0
Butanol 3.0
─────────────────────────────────────

  Then, it filtered with the filter paper (Toyo Filter Paper Co., Ltd. product # 63) with an absolute filtration accuracy of 0.01 mm, and further filtered with the filter paper (FH025 made by Paul Co., Ltd.) with an absolute filtration accuracy of 2.5 μm. The above-mentioned dope was heated to 35 ° C., and casted through a Giesser onto a mirror surface stainless steel drum having a diameter of 3 m set at −15 ° C. The Gieseer used was similar to that described in Japanese Patent Application Laid-Open No. 11-314233. The casting speed was 100 m / min and the casting width was 250 cm. After the residual solvent was peeled off at 200% by mass, the film was dried at 130 ° C. and wound up when the residual solvent became 1% by mass or less to prepare a cellulose acylate film. The obtained film was trimmed at both ends by 3 cm, and then a knurling having a height of 100 μm was imparted to a portion 2 to 10 mm from both ends, and wound into a 3000 m roll. The biaxially stretched film was used as a transparent support S-3 (Re = 10 nm, Rth = 40 nm).

(Preparation of alignment film composition AL-1)
The following composition was prepared, filtered through a polypropylene filter having a pore size of 30 μm, and used as an alignment film composition (coating liquid) AL-1.
─────────────────────────────────────
Coating liquid composition for alignment film (% by mass)
─────────────────────────────────────
Modified polyvinyl alcohol AL-1-1 3.85
Water 72.89
Methanol 22.83
Glutaraldehyde (crosslinking agent) 0.20
3-acryloxypropyltrimethoxysilane (manufactured by Kanto Chemical) 0.160
Citric acid 0.008
Citric acid monoethyl ester 0.029
Citric acid diethyl ester 0.027
Citric acid triethyl ester 0.006
─────────────────────────────────────

(Alignment film composition AL-2)
The following composition was prepared and filtered through a polypropylene filter having a pore size of 30 μm, and used as an alignment film composition AL-2.
──────────────────────────────────────
Coating liquid composition for alignment film (% by mass)
──────────────────────────────────────
Modified polyvinyl alcohol AL-1-2 3.85
Water 72.89
Methanol 22.83
Glutaraldehyde (crosslinking agent) 0.20
Glycidyl methacrylate (manufactured by Kanto Chemical) 0.160
Citric acid 0.008
Citric acid monoethyl ester 0.029
Citric acid diethyl ester 0.027
Citric acid triethyl ester 0.006
──────────────────────────────────────

(Preparation of coating liquid LC-1 for optically anisotropic layer)
After preparing the following composition, it filtered with the polypropylene filter with the hole diameter of 0.2 micrometer, and used as coating liquid LC-1 for optical anisotropic layers.
──────────────────────────────────────
Coating liquid composition for optically anisotropic layer (mass%)
──────────────────────────────────────
Rod-shaped liquid crystal (LC-1-1) 6.65
Rod-shaped liquid crystal (LC-1-2) 2.60
Chiral agent (LC-1-3) 21.07
Chiral agent (LC-1-4) 1.67
Chain transfer agent (LC-1-5) 0.67
Photopolymerization initiator (LC-1-6) 0.67
Styreneboronic acid 0.02
Methyl ethyl ketone 66.65
──────────────────────────────────────

LC-1-1:
Angew. Makromol. Chem. It was synthesized according to the method described in Journal, Vol. 183, p. 45 (1990).
LC-1-2:
It was synthesized by condensing 4- (6-acryloyloxyhexyloxy) benzoic acid synthesized by the method described in EP1174411B1 and 4-propylcyclohexylphenol (manufactured by Kanto Chemical).
LC-1-3:
4- (6-acryloyloxyhexyloxy) benzoic acid synthesized by the method described in EP1174411B1 and 4-hydroxy-4 ′-(2-methylbutyl) biphenyl synthesized by the method described in International Publication WO / 20010015454A1 Was synthesized by condensation.
LC-1-4:
It was synthesized by the method described in EP1389199A1.
LC-1-5:
Hydroxypropyl acrylate (manufactured by Aldrich) was mesylated, reacted with 4-propylcyclohexylphenol (manufactured by Kanto Chemical), and then hydrogen sulfide was added to synthesize.
LC-1-6:
4-Propylcyclohexylphenol (manufactured by Kanto Chemical Co., Ltd.) was triflated to give a biphenyl compound by Suzuki coupling reaction with phenylboronic acid. Furthermore, after acylating the 4′-position of biphenyl with isobutyric acid chloride and aluminum chloride, the carbon at the α-position of the carbonyl was brominated with bromine and then synthesized with a hydroxyl group with alkali.

(Preparation of coating liquid LC-2 for optically anisotropic layer)
After the following composition was prepared, it was filtered through a polypropylene filter having a pore size of 0.2 μm and used as a coating liquid LC-2 for an optically anisotropic layer.
──────────────────────────────────────
Coating liquid composition for optically anisotropic layer (mass%)
──────────────────────────────────────
Discotic liquid crystal (LC-2-1) 19.18
Additive (LC-2-2) 0.20
Photopolymerization initiator (LC-2-3) 0.60
Styreneboronic acid 0.02
Methyl ethyl ketone 80.00
──────────────────────────────────────

(Single-side saponification treatment of cellulose ester film)
The cellulose ester film was passed through a dielectric heating roll having a temperature of 60 ° C. and the film surface temperature was raised to 40 ° C., and then an alkali solution having the composition shown below was applied at 14 ml / m ² using a bar coater. Then, after retaining for 10 seconds under a steam far infrared heater (manufactured by Noritake Co., Ltd.) heated to 110 ° C., 3 ml / m ^{2 of} pure water was applied using the same bar coater. The film temperature at this time was 40 degreeC. Next, washing with a fountain coater and draining with an air knife were repeated three times, and then the sample was retained in a drying zone at 70 ° C. for 2 seconds and dried.

──────────────────────────────────────
Alkaline solution composition (mass%)
──────────────────────────────────────
Potassium hydroxide 4.7
Water 14.7
Isopropanol 64.8
Propylene glycol 14.8
Surfactant (SF-1) 1.0
──────────────────────────────────────

(Polarized UV irradiation device POLUV-1)
Using a microwave emission type ultraviolet irradiation device (Light Hammer 10, 240 W / cm, manufactured by Fusion UV Systems) equipped with D-Bulb having a strong emission spectrum at 350 to 400 nm as a UV light source, 10 cm away from the irradiation surface At the position, a wire grid polarizing filter (ProFlux PPL02 (high transmittance type), manufactured by Moxtek) was installed to produce a polarized UV irradiation apparatus. The maximum illuminance of this device was 400 mW / cm ² .

[Example 1]
One side of the transparent support S-1 was saponified using the above-described one-side saponification method, and then a photoacid generator diphenyliodonium hexafluorophosphate (manufactured by Kanto Chemical Co., Ltd.) of 4.0% by mass (as opposed to The alignment film composition (coating solution) AL-1 to which (solid content ratio) is added is applied with a # 14 wire bar coater and dried with 60 ° C. warm air for 60 seconds and further with 90 ° C. warm air for 150 seconds. An alignment film having a thickness of 1.0 μm was formed. Subsequently, after irradiating the alignment film with non-polarized UV (illuminance: 200 mW / cm ² , 100 mJ / cm ² ), the rubbing treatment was continuously performed in the slow axis direction of the transparent support, and then the optical The anisotropic layer coating liquid LC-1 was applied to the rubbing treated surface with a # 3 wire bar coater and heat-dried at 60 ° C. for 1 minute to form an optical anisotropic layer having a uniform liquid crystal phase. Further, after the aging, the transmission axis of the polarizing filter of the apparatus is a phase advance of the transparent support using the polarized UV irradiation apparatus POLUV-1 in a nitrogen atmosphere with an oxygen concentration of 0.3% or less with respect to the optically anisotropic layer. The optical film of Example 1 was produced by irradiating polarized UV (illuminance 200 mW / cm ² , irradiation amount 200 mJ / cm ² ) so as to be in the axial direction. The optically anisotropic layer showed no liquid crystal phase even when heated after fixing. The thickness of the optically anisotropic layer was 1.3 μm. The following evaluation was performed on the obtained optical film.

(Saponification resistance)
The produced compensation plate was immersed in a saponification solution (2.0N NaOH aqueous solution) at 60 ° C. for 3 minutes and washed with water. Subsequently, the presence or absence of peeling was visually observed, and the following three-stage evaluation was performed.
◯: No peeling was observed
Δ: 10% or more peeling was observed
X: 50% peeled off

(Phase difference measurement)
Retardation Re (40) and Re (−40) when a sample is tilted ± 40 degrees with KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) and front retardation Re at 589 nm and the slow axis as the rotation axis. It was measured. As Rth, a value calculated by KOBRA 21ADH was used. The phase difference of the optically anisotropic layer was determined by subtracting the phase difference of the support at each angle from the phase difference of the entire optical compensation sheet at each angle.

[Example 2]
An optical film was produced in the same manner as in Example 1 except that AL-1 was replaced with AL-2. The above-mentioned evaluation was performed with respect to the obtained optical film.

[Example 3]
One side of the transparent support S-1 was saponified using the above-described one-side saponification method, and then photoacid generator diphenyliodonium hexafluorophosphate (manufactured by Kanto Chemical Co.) 4.0% by mass (solid) The coating liquid AL-1 for alignment film to which the fraction ratio was added was applied with a # 14 wire bar coater and dried for 60 seconds with hot air at 60 ° C. and for 150 seconds with hot air at 90 ° C. An alignment film having a thickness of 0 μm was formed. Subsequently, after irradiating the alignment film with non-polarized UV (illuminance: 200 mW / cm ² , 100 mJ / cm ² ), the rubbing treatment was continuously performed in the slow axis direction of the transparent support, and then the optical The anisotropic layer coating liquid LC-2 was applied to the rubbing treated surface with a # 3 wire bar coater and heat-dried at 125 ° C. for 1 minute to form an optical anisotropic layer having a uniform liquid crystal phase. Further, after aging, the optical anisotropic layer is irradiated with polarized UV using the polarized UV irradiation apparatus POLUV-1 so that the transmission axis of the polarizing filter of the apparatus is in the fast axis direction of the transparent support ( The illuminance was 200 mW / cm ² and the irradiation amount was 200 mJ / cm ² ), and the optical film of Example 1 was produced. The optically anisotropic layer showed no liquid crystal phase even when heated after fixing. The thickness of the optically anisotropic layer was 1.3 μm. The above-mentioned evaluation was performed with respect to the obtained optical film.

[Example 4]
An optical film was produced in the same manner as in Example 1 except that the support S-1 was replaced with the support S-2. The above-mentioned evaluation was performed with respect to the obtained optical film.

[Example 5]
An optical film was produced in the same manner as in Example 3 except that the support S-1 was replaced with the support S-3 and the optically anisotropic layer coating liquid LC-1 was replaced with LC-2. The above-mentioned evaluation was performed with respect to the obtained optical film.

[Comparative Example 1]
After saponifying one side of the transparent support S-1 using the above-described one-side saponification method, the coating liquid AL-1 for alignment film is applied thereon with a # 14 wire bar coater and heated at 60 ° C. An alignment film having a thickness of 1.0 μm was formed by drying with warm air for 60 seconds and further with warm air at 90 ° C. for 150 seconds. Subsequently, after irradiating the alignment film with non-polarized UV (illuminance: 200 mW / cm ² , 100 mJ / cm ² ), the rubbing treatment was continuously performed in the slow axis direction of the transparent support, and then the optical The anisotropic layer coating liquid LC-1 was applied to the rubbing treated surface with a # 3 wire bar coater and heat-dried at 60 ° C. for 1 minute to form an optical anisotropic layer having a uniform liquid crystal phase. Further, immediately after the aging, the transmission axis of the polarizing filter of the apparatus is advanced to the transparent support using the polarized UV irradiation apparatus POLUV-1 in a nitrogen atmosphere having an oxygen concentration of 0.3% or less with respect to the optically anisotropic layer. The optical film of Comparative Example 1 was produced by irradiating polarized UV (illuminance 200 mW / cm ² , irradiation amount 200 mJ / cm ² ) so as to be in the phase axis direction. The optically anisotropic layer showed no liquid crystal phase even when heated after fixing. The thickness of the optically anisotropic layer was 1.3 μm. The above-mentioned evaluation was performed with respect to the obtained optical film.

[Comparative Example 2]
After saponifying one side of the transparent support S-1 using the above-described one-side saponification method, the coating liquid AL-1 for alignment film is applied thereon with a # 14 wire bar coater and heated at 60 ° C. An alignment film having a thickness of 1.0 μm was formed by drying with warm air for 60 seconds and further with warm air at 90 ° C. for 150 seconds. Subsequently, after irradiating the alignment film with non-polarized UV (illuminance: 200 mW / cm ² , 100 mJ / cm ² ), the rubbing treatment was continuously performed in the slow axis direction of the transparent support, and then the optical The anisotropic layer coating liquid LC-2 was applied to the rubbing treated surface with a # 3 wire bar coater and heat-dried at 125 ° C. for 1 minute to form an optical anisotropic layer having a uniform liquid crystal phase. Further, after aging, the optical anisotropic layer is irradiated with polarized UV using the polarized UV irradiation apparatus POLUV-1 so that the transmission axis of the polarizing filter of the apparatus is in the fast axis direction of the transparent support ( The illuminance was 200 mW / cm ² and the irradiation amount was 200 mJ / cm ² ) to produce an optical film of Comparative Example 2. The optically anisotropic layer showed no liquid crystal phase even when heated after fixing. The thickness of the optically anisotropic layer was 1.3 μm. The above-mentioned evaluation was performed with respect to the obtained optical film.

  The adhesion evaluation results of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 1, and the phase difference measurement results of Examples 1 to 5 and Comparative Example 1 are shown in Table 2.

[Table 1]
──────────────
Sample Resistance to saponification ──────────────
Example 1 ○
Example 2 ○
Example 3 ○
Example 4 ○
Example 5 ○
Comparative Example 1 ×
Comparative Example 2
──────────────

[Table 2]
─────────────────────────
Sample Re Re (40) Re (−40)
─────────────────────────
Example 1 9.6 61.5 60.5
Example 2 8.8 58.9 58.0
Example 3 11.5 61.0 60.5
Example 4 8.5 60.5 60.0
Example 5 13.9 61.2 67.1
Comparative Example 1 9.9 62.3 61.0
Comparative Example 2 12.8 62.3 60.4
─────────────────────────
(In the table, the Re value is the Re value of the optically anisotropic layer.)

(Preparation of polarizing plate with optical film)
The optical films of Examples 1 to 3 and 5 and Comparative Example 1 of the present invention and the commercially available Fujitac TD80UF (Fuji Photo Film Co., Ltd., Re = 3 nm, Rth = 50 nm) were hydroxylated at 1.5 mol / L. It was immersed in an aqueous sodium solution at 55 ° C. for 2 minutes. Subsequently, it was washed in a water bath at room temperature and neutralized at 30 ° C. with 0.05 mol / L sulfuric acid. This was washed again in a room temperature water bath and further dried with hot air at 100 ° C. Thereafter, washing with water and neutralization treatment were performed, and the two saponified films were attached to both surfaces of the polarizing film with a roll-to-roll using a polyvinyl alcohol adhesive as a protective film for the polarizing plate. A body-type polarizing plate was produced. All the examples of the present invention were excellent in productivity, and the optically anisotropic layer showed a good surface shape. The comparative example not only has insufficient adhesion, but also caused problems such as a decrease in productivity due to the saponification treatment on one side before coating of the alignment film, and contamination of the saponification bath during polarizing plate processing. .

[Example 6]
(Production of VA-LCD liquid crystal display device)
The lower polarizing plate of a commercially available VA-LCD (SyncMaster 173P, manufactured by Samsung Electronics Co., Ltd.) is peeled off, and the polarizing plate with an optical film of the present invention produced in Example 1 is applied to the glass surface of the liquid crystal cell substrate. The liquid crystal display device of the present invention was produced by bonding with an adhesive. A schematic cross-sectional view of the manufactured liquid crystal display device is shown in FIG. 4 together with the angular relationship of the optical axes of the respective layers. In FIG. 4, 41 is a polarizing layer, 42 is a transparent support, 43 is an alignment film, 44 is an optically anisotropic layer (an optical film is composed of 41 to 44), 45 is a polarizing plate protective film, and 46 is a liquid crystal cell. A glass substrate, 47 is a liquid crystal cell, and 48 is an adhesive layer. Further, the arrow in the polarizing layer 41 indicates the direction of the absorption axis, the arrow in the optically anisotropic layer 44 or its support 44 and the protective film 45 indicates the direction of the slow axis, and the circle indicates the direction of the arrow relative to the paper surface. Indicates the line direction.

(Evaluation of VA-LCD liquid crystal display device)
The viewing angle characteristics of the manufactured liquid crystal display device were measured with a viewing angle measuring device (EZ Contrast 160D, manufactured by ELDIM). Furthermore, it evaluated also visually about 45 degree | times diagonally especially. FIG. 5 shows the contrast characteristics by EZ Contrast of Example 6 and Table 3 shows the visual evaluation results.

[Table 3]
────────────────────────────────────
Sample Visual evaluation results ─────────────────────────────────────
Example 6 Both white display and black display have little color misregistration and good halftone gradation characteristics ─────────────────────────── ─────────

  ADVANTAGE OF THE INVENTION According to this invention, the orientation film which is excellent in adhesiveness with an optically anisotropic layer, and does not elute and peel by a saponification process can be provided. The alignment film of the present invention can be suitably used for a VA mode liquid crystal display device.

It is the schematic which shows an example of the liquid crystal display device of this invention. It is a schematic sectional drawing of the example of the polarizing plate of this invention. It is a schematic sectional drawing of an example of the liquid crystal display device of this invention. It is the schematic sectional drawing which showed the layer structure of the liquid crystal display device produced in Example 6 with the direction of the optical axis in a layer. FIG. 11 is a graph showing contrast characteristics of the liquid crystal display device manufactured in Example 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Transparent support 12 Optically anisotropic layer 13 which consists of liquid crystalline composition Orientation film 21 Polarizing layers 22, 23 Protective film 24 Functional layer 31, such as (lambda) / 4 board, antireflection film 31, Cold cathode tube 32 Reflective sheet 33 Light plate 34 Light control film 35 such as brightness enhancement film, diffusion film, etc. Liquid crystal cell 36 Lower polarizing plate 37 Upper polarizing plate 41 Polarizing layer 42 Transparent support 43 Alignment film 44 Optical anisotropic layer 45 Polarizing plate protective film 46 Glass for liquid crystal cell Substrate 47 Liquid crystal cell 48 Adhesive 51 Uniaxially stretched optical film

Claims (14)

  An alignment film composition used for the production of an optical film having an optically anisotropic layer comprising a support, an alignment film, and a liquid crystalline composition containing a liquid crystal compound, and having a reactive group in the side chain An alignment film composition comprising at least a molecule, a compound having an ethylenically unsaturated bond, a photoacid generator, and a solvent containing 20% by mass or more of water.   The alignment film composition according to claim 1, wherein the photoacid generator is a water-soluble compound.   The alignment film composition according to claim 2, wherein the photoacid generator is an iodonium salt or a sulfonium salt.   The alignment film composition according to any one of claims 1 to 3, wherein the polymer is at least one selected from a polyvinyl alcohol derivative having a polymerizable group in a side chain, a poly (meth) acrylate derivative, and a polysaccharide. .   A step of coating and drying the alignment film composition according to any one of claims 1 to 4 on a support to form a coating film, a step of irradiating the coating film with light, and a coating irradiated with the light An alignment film manufactured by a manufacturing method having steps of rubbing the film in this order.   The alignment film composition according to any one of claims 1 to 4 is coated on the support and dried to form a coating film, the coating film is rubbed, and the rubbed coating film is irradiated with light. An alignment film manufactured by a manufacturing method having irradiation steps in this order.   7. An optical film having an optically anisotropic layer comprising a support, an alignment film, and a liquid crystalline composition containing a liquid crystal compound, wherein the alignment film is the alignment film according to claim 5 or 6, and the optically different film. An optical film, wherein an isotropic layer is formed from a polymer of the liquid crystalline compound.   The optical film according to claim 7, wherein the liquid crystal compound includes a discotic liquid crystal compound.   The optical film according to claim 7, wherein the liquid crystal compound includes a rod-like liquid crystal compound.   The optical film according to claim 7, wherein the liquid crystal composition is a liquid crystal composition containing a rod-like liquid crystal compound and a chiral agent.   The front retardation (Re) of the optically anisotropic layer is not 0, and the wavelength λ nm from the direction inclined + 40 ° with respect to the normal direction of the optical film with the in-plane slow axis as the tilt axis (rotation axis) The retardation value measured by making light incident and the slow axis in the plane as the tilt axis (rotation axis) make light of wavelength λ nm incident from a direction inclined by −40 ° with respect to the normal direction of the optical film. The measured retardation value is substantially equal, The optical film of any one of Claims 7-10 characterized by the above-mentioned.   The polarizing plate which has an optical film of any one of Claims 7-11, and a polarizing film.   The liquid crystal display device which has an optical film of any one of Claims 7-11, or a polarizing plate of Claim 12.   The liquid crystal display device according to claim 13, which is in a VA mode.

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