JP2012087197A - Alkali resistance improver, photocurable liquid crystal composition, optical film, polarizing plate and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the alkali resistance of a cured film composed of a curable composition.SOLUTION: This alkali resistance improver for curable compositions includes at least one α-alkylamine. Further. the curable composition contains at least a polymerization initiator, a sensitizer, one or more polymerizable liquid crystal compounds, and the alkali resistance improver. An optical film has an optically anisotropic layer composed of the composition.

Description

  The present invention is an alkali resistance improver useful for improving the alkali resistance of a cured film made of a curable composition, and a photocurable composition useful for producing an optical member such as an optical film containing the same. In addition, the present invention relates to an optical film, a polarizing plate, and a liquid crystal display device using the same.

Conventionally, an optically anisotropic layer formed from a photocurable liquid crystal composition has been used for optical compensation of a liquid crystal display device. The curable liquid crystal composition generally contains a polymerization initiator for initiating a polymerization reaction together with a liquid crystal compound. Furthermore, for the purpose of improving the sensitivity of the curable composition or for the purpose of improving the strength of the cured film, it has been proposed to add a sensitizer or a co-sensitizer to the composition. (For example, Patent Documents 1 to 4).
Various liquid crystal compounds have been proposed in order to achieve more ideal optical compensation capability (for example, Patent Documents 5 and 6).

  Incidentally, an optical compensation film having an optically anisotropic layer is generally incorporated in a liquid crystal display device as a polarizing plate integrated with a polarizing film. In order to improve the adhesion to the polarizing film, the optical compensation film is generally subjected to an alkali saponification treatment. In the alkali saponification treatment, since the optical compensation film is immersed in an alkali solution, there is a problem that the optically anisotropic layer is deteriorated by the alkali solution.

[0035] of JP-A-7-325221 [0049] of JP 2007-86248 A JP 2008-201912 A [0051] of JP2009-237362A JP 2007-2220 A JP 2007-204705 A

As a result of studies by the present inventors, it has been found that the film thickness of the optically anisotropic layer is significantly reduced by the alkali saponification treatment. Adding a sensitizer or co-sensitizer to the curable composition contributes to improving the photosensitivity and the strength of the cured film, but on the other hand, adding a sensitizer or a co-sensitizer to cure It has been found that even when the strength of the film is improved, the deterioration of the optically anisotropic layer due to the alkali saponification treatment may not be alleviated. In some cases, it was found that when the film strength was improved, the alkali resistance could even decrease.
This invention is made | formed in view of the said problem, Comprising: It aims at providing the agent which can improve the alkali tolerance of the cured film which consists of a curable composition.
Another object of the present invention is to provide a curable liquid crystal composition capable of forming a cured film in which the variation in film thickness is reduced before and after the alkali saponification treatment.
In addition, the present invention provides an optical film, a polarizing plate, and a liquid crystal display device having an optically anisotropic layer made of a liquid crystal composition that has little change in optical properties before and after alkali saponification treatment and has good durability. Is an issue.

Means for solving the above problems are as follows.
[1] An alkali resistance improver for a curable composition comprising at least one α-alkylamine.
[2] The alkali resistance improver for a curable composition according to [1], wherein the α-alkylamine is an α-alkylamine having an aromatic ring directly bonded to a nitrogen atom.
[3] The alkali resistance improver for a curable composition according to [1], wherein the α-alkylamine is an aliphatic α-alkylamine.
[4] The alkali resistance improver for a curable composition according to [1], wherein the α-alkylamine is an α-alkylamine containing an aromatic ring bonded to a nitrogen atom via a linking group.
[5] The alkali resistance improver for a curable composition according to any one of [1] to [4], wherein the α-alkylamine is a tertiary amine bonded to a nitrogen atom.
[6] A curable liquid crystal composition containing at least one polymerization initiator, one or more polymerizable liquid crystal compounds, and at least one alkali resistance improver of [1] to [5].
[7] The one or more polymerizable liquid crystal compounds have a disk-shaped core and two or more side chains bonded to the atoms constituting the disk-shaped core, and the side chain has an ester bond. A curable liquid crystal composition according to [6].
[8] The one or more polymerizable liquid crystal compounds have a discotic core and two or more side chains bonded to atoms constituting the discotic core, and the side chains are oxadiazole. [6] or [7] curable liquid crystal composition having one or more rings.
[9] The above [1] or [8], wherein the one or more polymerizable liquid crystal compounds are 1,3,5-substituted benzene derivatives or 1,2,7,8,13,14-substituted triphenylene derivatives. Any curable liquid crystal composition.
[10] The alkali resistance improver is contained in a molar ratio of 0.1 × 10 ^{2 to} 2.0 × 10 ² with respect to the one or more polymerizable liquid crystal compounds [6] to [9]. A curable liquid crystal composition according to any of the above.
[11] Further containing at least one sensitizer, and containing the alkali resistance improver in a molar ratio of 0.1 to 1.5 with respect to the sensitizer [6] to [10 ] The curable liquid crystal composition in any one of.
[12] The curable liquid crystal according to any one of [6] to [11], further containing at least one sensitizer and 0.1 to 10% by mass in total of the polymerization initiator and the sensitizer. Composition.
[13] An optical film having a polymer film and an optically anisotropic layer obtained by curing the curable liquid crystalline composition of any one of [6] to [12] on the polymer film.
[14] The optical film according to [13], wherein a contact angle of the surface of the optically anisotropic layer after the alkali solution treatment is 60 to 95 °.
[15] The optical film of [13] or [14], which has been subjected to alkali saponification treatment.
[16] A polarizing plate having the optical film of any one of [13] to [15] and a polarizing film.
[17] A liquid crystal display device having the optical film of any one of [13] to [15] and / or the polarizing plate of [16].

ADVANTAGE OF THE INVENTION According to this invention, the agent which can improve the alkali tolerance of the cured film which consists of a curable composition can be provided.
Moreover, according to this invention, the curable liquid-crystal composition which can form the cured film with which the fluctuation | variation of the film thickness was reduced before and after the alkali saponification process can be provided.
In addition, according to the present invention, there are provided an optical film, a polarizing plate, and a liquid crystal display device having an optically anisotropic layer made of a liquid crystal composition with little fluctuation in optical properties before and after alkali saponification treatment and good durability. can do.

It is a graph which shows the relationship between the addition amount of the alpha-alkylamine used in the Example, and an alkali tolerance improvement effect. It is a graph which shows the relationship between the addition amount of the alpha-alkylamine used in the Example, and an alkali tolerance improvement effect. It is a graph which shows the relationship between the addition amount of the alpha-alkylamine used in the Example, and an alkali tolerance improvement effect.

  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.

1. TECHNICAL FIELD The present invention relates to an alkali resistance improver for a curable composition comprising at least one α-alkylamine. The alkali resistance improving agent of the present invention is an agent that can improve the alkali resistance of a cured film of the composition by being added to the curable composition. Since the curable composition containing the alkali resistance improver of the present invention has improved alkali resistance, deterioration is suppressed even when immersed in an alkaline solution. For example, when an optical film in which a cured film made of a curable composition is formed on a polymer film is bonded to another member (for example, a polarizing film), an alkali saponification treatment may be performed. Even if it exists, according to this invention, deterioration of the cured film by an alkali saponification process can be suppressed.

  The inventor examined the deterioration of the cured film before and after the alkali saponification treatment, and found that when the cured film was immersed in an alkaline solution for the alkali saponification treatment, the film thickness was significantly reduced. Further examination of this cause revealed that the polymerizable component was oxidized during the curing reaction and the oxide was eluted into the alkaline solution. As a result of further investigation, it was found that when α-alkylamine was added to the curable composition, oxidation of the polymerizable component was suppressed, and the alkali resistance of the cured film was remarkably improved, and the present invention was completed. It was. The details of the addition of α-alkylamine to improve the alkali resistance of the cured film are unclear, but one reason is that the polymerization is promoted by allowing the polymerization reaction to proceed in the presence of α-alkylamine. Thus, it can be estimated that the strength of the cured film is improved. However, improvement in alkali resistance cannot be achieved only by improving the strength of the cured film. For example, even if it is a polymerization accelerator, the thiol polymerization accelerator has no effect of improving alkali resistance. Furthermore, it can be assumed that the inhibition of oxygen by the addition of α-alkylamine contributes to the suppression of oxidation of the polymerization component, which contributes to the improvement effect of alkali resistance. Even when a known hindered amine is added as an agent, improvement in alkali resistance cannot be achieved. That is, the action of the alkali resistance improving agent of the present invention is different from any action of conventional polymerization accelerators and antioxidants.

  α-Alkylamine refers to an amine in which the α-position is an alkyl group. Examples of α-alkylamines include any of primary amines, secondary amines, and tertiary amines. The α-position alkyl group may have a substituent, and examples of the substituent include a carboxyl group, a hydroxy group, and an alkoxy group. The alkyl group may be linear or branched. The alkyl group preferably has 1 to 14 carbon atoms, and more preferably 1 to 6 carbon atoms from the viewpoint of the molecular weight of the α-alkylamine described later. When the α-alkylamine has two or more substituents at the α-position, that is, when the α-alkylamine is a secondary amine or a tertiary amine, the other α-position substituents are alkyl groups. Alternatively, it may be a substituent other than an alkyl group. Those having one or more aromatic rings (preferably benzene rings) are preferable, and N-aryl-α-alkylamines having an aromatic ring directly bonded to a nitrogen atom are particularly preferable.

The α-alkylamine that can be used in the present invention is classified into the following groups I to III depending on the tendency of the alkali resistance improving effect with respect to the added amount.
Group I: N-aryl-α-alkylamines having an aromatic ring directly bonded to the nitrogen atom. This group includes both secondary amines, tertiary amines and glycine derivatives. For example, the following compounds are exemplified.

  When the amount of α-alkylamine belonging to Group I is increased, the alkali resistance improving effect increases depending on the amount added. However, when the added amount exceeds the predetermined range, the effect is reduced. The preferable addition amount range is wide, the handling property is good, and there are advantages that the alkali resistance effect is excellent.

Group II: aliphatic α-alkylamines containing no aromatic ring. This group includes both primary, secondary and tertiary amines. For example, the following compounds are exemplified.

  The α-alkylamine belonging to Group II has a characteristic that the alkali resistance improvement effect increases depending on the addition amount when the addition amount is increased, and the effect decreases when the addition amount exceeds a predetermined range. The point of showing is common with the group I, however, the preferable addition amount range is narrower than the group I, and the group I is preferable from the viewpoint of handling.

Group III: α-alkylamine containing an aromatic ring bonded to a nitrogen atom via a linking group (for example, an alkylene group). This group includes secondary and tertiary amines, with tertiary amines being preferred. For example, the following compounds are exemplified.

  The α-alkylamine belonging to Group III has a characteristic that the alkali resistance improvement effect increases depending on the addition amount when the addition amount is increased, and the effect decreases when the addition amount exceeds a predetermined range. The point of showing is the same as that of Group I and Group II, but the effect is smaller than that of Group I and Group II, and Group I and Group II are preferred from the viewpoint of the effect of improving alkali resistance. However, since the preferable addition amount range is wide, the handleability is excellent. In addition, α-alkylamines belonging to any group do not have a hydrogen atom bonded to a nitrogen atom, that is, a tertiary amine tends to have a particularly high alkali resistance improving action.

  Although there is no restriction | limiting in particular about the molecular weight of the alpha-alkylamine concerning this invention, It is preferable that it is about 100-300 from a viewpoint of the cured film strength improvement. However, it is not limited to this range as long as it shows the effect of improving alkali resistance.

2. Curable liquid crystal composition The present invention also relates to a curable liquid crystal composition containing at least a polymerization initiator, a sensitizer, one or more polymerizable liquid crystal compounds, and the alkali resistance improver of the present invention. A cured film in which the curable liquid crystal composition of the present invention is cured and then cured to fix the alignment state exhibits optical properties based on the alignment. The optical characteristics can be used for optical compensation of a liquid crystal display device.

Polymerizable liquid crystal compound:
Liquid crystal compounds are generally classified into rod-like and disk-like liquid crystal compounds based on their molecular shapes. Examples of polymerizable liquid crystal compounds that can be used in the present invention include liquid crystal compounds of any shape. Is also included.

Rod-like liquid crystal compound Examples of the rod-like liquid crystal compound that can be used as the liquid crystal compound in the present invention include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters. Cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles. Further, as the rod-like liquid crystal compound, not only the above low molecular liquid crystal compound but also a polymer liquid crystal compound can be used.

-Discotic liquid crystal compounds (discotic liquid crystal compounds)
Examples of discotic liquid crystal compounds include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

  The discotic liquid crystal compound has a structure in which a linear alkyl group, an alkoxy group, or a substituted benzoyloxy group is radially substituted as a side chain of the mother nucleus with respect to the mother nucleus (discotic core) at the molecular center. Also included are compounds exhibiting liquid crystallinity. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation.

  Examples of the disk-shaped core include the following partial structures, but are not limited thereto. In the following formula, LQ is a side chain bonded to the discotic core, L represents a divalent linking group, and Q represents a polymerizable group.

  Preferred examples of the discotic liquid crystal compound include paragraph number [0052] in JP-A-8-50206 and JP-A-2006-76992, and paragraph number [0040] in JP-A-2007-2220. To [0063]. For example, the compounds represented by the following general formulas (DI) and (DII) are preferable because they exhibit high birefringence. Further, among the compounds represented by the following general formulas (DI) and (DII), compounds showing discotic liquid crystallinity are preferable, and compounds showing a discotic nematic phase are particularly preferable. Details of the following compounds (definition of symbols in the formula and preferred ranges thereof) are specifically described in the above publication.

  In addition, preferable examples of the discotic liquid crystal compound include compounds described in JP-A-2005-301206.

  As a result of the study by the present inventors, in particular, the alkali resistance improver of the present invention has a disk-shaped core and two or more side chains bonded to atoms constituting the disk-shaped core, and the side chains However, it turned out that a high effect is shown with respect to the curable composition which used the polymeric liquid crystal compound which has an ester bond as a polymerization component. The alkali resistance improver of the present invention has a disk-shaped core and two or more side chains bonded to atoms constituting the disk-shaped core, and the side chain has one oxadiazole ring. It was found that a high effect was exhibited with respect to the curable composition using the polymerizable liquid crystal compound having the above as a polymerization component. The polymerizable liquid crystal compound is preferably a 1,3,5-substituted benzene derivative or a 1,2,7,8,13,14-substituted triphenylene derivative, that is, the above formula (DI) or (DII) The polymerizable liquid crystal compound represented by is preferable. It is also preferable to use these in combination. Among them, the compound represented by the above formula (DI) is preferable as the material of the optically anisotropic layer used for the optical compensation ability because the wavelength dispersion characteristic is closer to ideal.

  An example of the polymerizable liquid crystal compound that can be used in the present invention is a compound represented by the following formulas (DIa) and (DIIa).

In the formula, each R ¹ represents a substituent having one or more ester bonds and having a polymerizable group at the terminal; R ² represents a substituent having a polymerizable group at the terminal. Examples of the polymerizable group include the following examples.

Specific examples of R ¹ and R ² include the following. However, in the following specific examples, the terminal polymerizable group was omitted. “*” Represents a position bonded to the ring in the above formulas (DIa) and (DIIa), and “**” represents a position bonded to the polymerizable group. Further, the group that does not contain an ester bond of the following embodiment, a specific example of only R ^2. In the following formulae, AL represents an alkylene group (preferably an alkylene group having 1 to 20 carbon atoms, more preferably an alkylene group having 2 to 10 carbon atoms), one carbon atom, or two or more carbon atoms not adjacent to each other, An oxygen atom, -NR- (wherein R is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms) or a sulfur atom). In the following formulas, AR represents an arylene group (including aromatic carbocyclic and aromatic heterocyclic groups, such as a phenylene group and an oxadiazolyl group).
* -AL-CO-O-AL-**
* -AL-CO-O-AL-O-**
* -AL-CO-O-AL-O-AL-**
* -AL-CO-O-AL-O-CO-**
* -AL-CO-O-AL-O-CO-**
* -CO-AR-O-AL-**
* -CO-AR-O-AL-O-**
* -CO-AR-O-AL-O-CO-**
* -CO-NH-AL-**
* -NH-AL-O-**
* -NH-AL-O-CO-**
* -O-AL-**
* -O-AL-O-**
* -O-AL-O-CO-**
* -O-AL-O-CO-NH-AL-**
* -O-AL-S-AL-**
* -O-CO-AR-O-AL-CO-**
* -O-CO-AR-O-AL-O-CO-**
* -O-CO-AR-O-AL-O-AL-O-CO-**
* -O-CO-AR-O-AL-O-AL-O-AL-O-CO-**
* -S-AL-**
* -S-AL-O-**
* -S-AL-O-CO-**
* -S-AL-S-AL-**
* -S-AR-AL-**

When R ¹ and R ² include an alkylene chain, the length of the alkylene chain may affect the alkali resistance. For example, when R ^{1 includes} * -AL-CO-O-AL-O-CO-**, the alkali resistance tends to be improved as the total number of carbon atoms of two ALs increases. 5-15 are preferable, as for the sum total of the carbon atom number of two AL, 6-12 are preferable and 6-10 are more preferable.

  In the present invention, it is preferable to use at least one polymerizable liquid crystal compound represented by the above formulas (DIa) and (DIIa), and at least one polymerizable liquid crystal compound represented by the above formula (DIa) is used. Is more preferable. It is also preferable to use both of the polymerizable liquid crystal compounds represented by the above formulas (DIa) and (DIIa). In the embodiment using both, it is preferable that the ratio of the compound represented by the formula (DIa) is higher not only from the viewpoint of wavelength dispersion characteristics but also from the viewpoint of alkali resistance.

Polymerization initiator:
The polymerization initiator used in the present invention is preferably a photopolymerization initiator, and a polymerization initiator having a function of generating a polymerization active radical by light irradiation (preferably ultraviolet irradiation) is preferable. The alkali resistance improver of the present invention is particularly effective in combination with a hydrogen abstraction type polymerization initiator. Examples of the hydrogen abstraction type polymerization initiator include thioxanthone photopolymerization initiators such as benzophenone, Michler's ketone, dibenzosuberone, 2-ethylanthraquinone, isobutylthioxanthone, α-aminoalkylphenone photopolymerization initiator, etc. included. Commercial products may be used, and for example, “Ilquagua 907” (manufactured by Ciba Japan), “C0292” (manufactured by Tokyo Chemical Industry Co., Ltd.) and the like can be preferably used.

Sensitizer:
In the present invention, in order to accelerate the polymerization reaction of the polysynthetic liquid crystal compound, another photopolymerization initiator may be used in combination with the hydrogen abstraction type polymerization initiator as a sensitizer. For example, “Ilquagua 907” (manufactured by Ciba Japan) and “Kayacure DETX” (manufactured by Nippon Kayaku) can be preferably used in combination.

The preferable range of the content of the alkali resistance improver in the curable liquid crystal composition of the present invention varies depending on the type of the alkali resistance improver used, but a molar ratio with respect to the one or more polymerizable liquid crystal compounds. 0.1 × 10 ^{2 to} 2.0 × 10 ² is preferable, 0.2 × 10 ^{2 to} 1.5 × 10 ² is more preferable, and 0.2 × 10 ^{2 to} 1.2 More preferably, it is × 10 ² .
In an embodiment using the above-mentioned group II α-alkylamine as the alkali resistance improver, the preferred range will be narrow, and the effect will be exhibited with a smaller content. An example of a preferable content of the α-alkylamine of Group II is 0.05 × 10 ^{2 to} 1.5 × 10 ² in molar ratio with respect to the one or more polymerizable liquid crystal compounds, and other examples are a ^{0.05 × 10 2 ~1.2 × 10 2} , another example is ^{0.07 × 10 2 ~1.2 × 10 2} .
In the embodiment using the above-mentioned group II α-alkylamine as the alkali resistance improver, the preferred range will be the same as above or wider.

  Moreover, the alkali tolerance of the cured film which consists of a curable liquid crystal composition of this invention may be influenced by the ratio of the alkali tolerance improvement agent of this invention, and the said sensitizer. The alkali resistance improver of the present invention preferably has a molar ratio of 0.1 to 1.5, more preferably 0.2 to 1.3, relative to the sensitizer. A ratio of 0.3 to 1.2 is more preferable. When the proportion of the sensitizer is less than the above range, the strength of the optically anisotropic layer is lowered. On the other hand, when the proportion of α-alkylamine is less than the above range, the alkali resistance improving effect tends to decrease.

Moreover, the alkali tolerance of the cured film which consists of a curable liquid crystal composition of this invention may be influenced by the total amount of the said polymerization initiator and the said sensitizer. As the total amount of the polymerization initiator and the sensitizer increases, the strength of the optically anisotropic layer formed is improved, while the alkali resistance tends to decrease. It is preferable to contain 0.1 to 10% by mass of the polymerization initiator and the sensitizer in total, more preferably 0.5 to 8% by mass, and more preferably 0.6 to 6% by mass. Even more preferred.
Moreover, it is preferable to contain the said alkali tolerance improvement agent in 0.1-2.5 mass%, It is more preferable to contain in 0.1-2 mass%, 0.1-1.5 It is more preferable to contain in the range of mass%. However, the preferred range varies depending on the type of α-alkylamine, and therefore is not limited thereto.

Other additives:
The curable liquid crystal composition of the present invention may contain other additives in addition to the above essential components. For example, an alignment controller that controls the alignment of the polymerizable liquid crystal compound (including an air interface alignment controller and an alignment film interface alignment controller, specifically, a fluorine-based polymer, an onium salt, etc.), a non-liquid crystal Polymerizable compounds.

Application mode:
The curable liquid crystal composition of the present invention may be prepared as a coating solution. Examples of the organic solvent used for preparing the coating solution include amide (eg, N, N-dimethylformamide), sulfoxide (eg, dimethyl sulfoxide), heterocyclic compound (eg, pyridine), hydrocarbon (eg, benzene, Hexane), alkyl halides (eg, chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane) included. Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

3. Optical film TECHNICAL FIELD This invention relates to the optical film which has a polymer film and the optically anisotropic layer formed by hardening | curing the curable liquid crystalline composition of this invention on this polymer film. The optical film of the present invention can be used for various applications, for example, an optical compensation film for a liquid crystal display, a protective film for a polarizing plate, and the like by adjusting the optical characteristics of the optically anisotropic layer. In particular, since the alkali resistance of the optically anisotropic layer is improved, it is suitable as an optical member requiring an alkali saponification treatment.

  One example of the method for producing an optical film of the present invention is to apply a coating liquid of a curable liquid crystal composition on the surface of a polymer film, to bring the composition into a desired alignment state, and to cure the curable liquid crystal composition. To fix the orientation state. The surface on which the curable liquid crystal composition is applied is preferably subjected to an alignment treatment. For example, an alignment film is formed on a polymer film, and the surface of the film is applied to a rubbing treatment surface. Is preferred. As the alignment film, unmodified or modified polyvinyl alcohol or the like can be used.

  The curable liquid crystal composition is applied by a known method (for example, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method, curtain coating method, spin coating dip coating). , Ing method, print coating method, spray coating method, slot coating method, roll coating method, slide coating method, blade coating method, gravure coating method).

  After applying the curable liquid crystal composition, the photocurable liquid crystal composition can be brought into a desired alignment state by removing the solvent and drying. If desired, it may be heated. There is no restriction | limiting in particular about the orientation state of a curable liquid crystal composition, A desired optical characteristic will be determined according to a use, and an orientation state will also be determined according to it. Various alignment states such as horizontal alignment, vertical alignment, and hybrid alignment can be selected.

In order to fix the alignment state of the curable liquid crystal composition, a curing reaction such as a polymerization reaction is allowed to proceed. The polymerization reaction is preferably advanced by light irradiation, and ultraviolet rays are preferably used. The irradiation energy is not particularly limited but is preferably ^{20mJ / cm 2 ~50J / cm 2} , more preferably ^{20mJ / cm 2 ~5000mJ / cm 2} , 100mJ / cm 2 ~800mJ / cm 2 is more preferable. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. Although there is no restriction | limiting in particular as temperature for fixing orientation, Generally 100 degreeC or less is preferable and 80 degreeC or less is more preferable.

  Although there is no restriction | limiting in particular about the light irradiation system utilized for light irradiation, In order to improve the alkali tolerance of the optically anisotropic layer formed more, the ultraviolet rays from which short wavelength ultraviolet rays (254 nm or less ultraviolet rays) were removed were used. Preferably, a system capable of irradiation is used. As an example, there is a system that can irradiate ultraviolet rays through a short wavelength ultraviolet cut filter.

  Although there is no restriction | limiting in particular as thickness of the said optically anisotropic layer, Generally 0.1-20 micrometers is preferable, 0.5-15 micrometers is more preferable, 1-10 micrometers is still more preferable.

  There is no restriction | limiting in particular about the said polymer film. Depending on the application, it can be selected from various polymer films. Depending on the application, it is required to use a polymer film excellent in optical performance transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like. Examples of the main polymer of the polymer film that can be used in the present invention include polycarbonate polymers, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymers, and the like. Examples thereof include styrenic polymers such as (AS resin). Polyolefins such as polyethylene and polypropylene, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers , Polyether ether ketone polymer, polyphenylene sulfide polymer, vinylidene chloride polymer, vinyl alcohol polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or a polymer mixed with the above polymers. included.

  In addition, a thermoplastic norbornene resin can be preferably used as the main component polymer of the polymer film. Examples of the thermoplastic norbornene-based resin include ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., and ARTON manufactured by JSR Corporation.

  As the polymer film, cellulose acylate represented by triacetyl cellulose, which has been conventionally used as a transparent protective film for polarizing plates, can be preferably used.

  In the cellulose acylate film, since the hydroxyl group of cellulose is substituted with an acyl group, adhesion to a hydrophilic member (for example, a polarizing film made of polyvinyl alcohol) may be low. In such a case, it is usual to improve the adhesion to the hydrophilic member by alkali saponification treatment. Since the optically anisotropic layer of the optical film of the present invention has improved alkali resistance, deterioration can be reduced even when immersed in an alkali solution for alkali saponification treatment. Therefore, in this invention, the aspect which uses a cellulose acylate film as a polymer film which is a support body of an optically anisotropic layer is one of the preferable aspects.

  Although there is no restriction | limiting in particular about the thickness of the said polymer film, Generally, it is preferable that it is 10-1000 micrometers, It is more preferable that it is 40-500 micrometers, It is especially preferable that it is 40-200 micrometers.

The optically anisotropic layer included in the optical film of the present invention exhibits high alkali resistance. One of the indices indicating the degree of alkali resistance is the contact angle on the surface of the optically anisotropic layer after the alkali treatment liquid. A larger contact angle indicates a higher alkali resistance. Since the optically anisotropic layer is made of a hydrophobic material, the optically anisotropic layer has low hydrophilicity and usually has a water contact angle of about 100 °. When the alkali resistance is low, the contact angle of the optically anisotropic layer is remarkably lowered when the alkali solution is used. Even after the optical film of the present invention has been treated with an alkali solution (in this specification, a treatment immersed in a 1.5 mol / L sodium hydroxide solution for 2 minutes), The contact angle of water is small, and a contact angle of 60 to 95 ° can be achieved, and 70 to 95 ° can be achieved.
The contact angle is measured according to JIS K6768 using a contact angle meter DM500 manufactured by Kyowa Interface Science Co., Ltd.

  In addition, as another example of an index indicating the degree of alkali resistance, the change in the thickness of the optically anisotropic layer before and after the alkali solution treatment is small, and the in-plane of the optically anisotropic layer before and after the alkali solution treatment The change in retardation Re is small. The optical film of the present invention can achieve a film thickness reduction of less than 20 nm after the alkali solution treatment. The optical film of the present invention can achieve a Re change of 2 nm or less after the alkali solution treatment.

4). Polarizing plate The present invention also relates to a polarizing plate comprising at least the optical film of the present invention and a polarizing film. The optical film of the present invention is preferably subjected to an alkali saponification treatment in order to improve adhesion with the polarizing film. There is no restriction | limiting in particular about alkali saponification process, It can carry out by a general method. For example, it can be performed by the method described in JP-A-2001-100033.

Polarizing film:
In the present invention, a general linearly polarizing film (sometimes simply referred to as “polarizing film” in this specification) can be used. For example, a polarizer film made of a polyvinyl alcohol film dyed with iodine or a dichroic dye can be used.

Adhesive layer or adhesive:
In the present invention, an adhesive layer may be disposed between the optical film and the polarizing film. There is no restriction | limiting in particular about an adhesive, For example, a polyvinyl alcohol-type adhesive can be used. In addition, an adhesive may be used for bonding, for example, a polyvinyl alcohol resin (including a modified polyvinyl alcohol by an acetoacetyl group, a sulfonic acid group, a carboxyl group, or an oxyalkylene group) or a boron compound aqueous solution as an adhesive. Can be used. Of these, polyvinyl alcohol resins are preferred.
The thickness of the pressure-sensitive adhesive layer and the adhesive layer is preferably in the range of 0.01 to 10 μm after drying, and particularly preferably in the range of 0.05 to 5 μm.

Protective film:
It is preferable to arrange a protective film on the other surface where the optical film of the polarizing film is not bonded. Examples of the polymer film that can be used as the protective film are the same as those of the polymer film that can be used as the transparent support of the optical film.

Other layers:
The polarizing plate of the present invention may have other functional layers such as an antireflection layer, a hard coat layer, a forward scattering layer, a primer layer, an antistatic layer, and an undercoat layer.

5. Applications of optical film and polarizing plate of the present invention The optical film and polarizing plate of the present invention can be used for image display devices, particularly liquid crystal display devices. The optical film and the polarizing plate include TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-ferroelectric Liquid N crystal, OCB (Optical Liquid NIST). ), VA (Vertically Aligned), and HAN (Hybrid Aligned Nematic), and can be used for liquid crystal display devices in any display mode.

  Hereinafter, the present invention will be described in more detail based on 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 following examples.

1. Preparation of Optical Film 1- (1) Preparation of Polymer Film A cellulose acetate film mainly composed of cellulose acetate (degree of acetylation 60.9%) was prepared. This cellulose acetate film is passed through a dielectric heating roll having a temperature of 60 ° C. and the film surface temperature is raised to 40 ° C., and then an alkali solution having the composition shown below is applied on one side of the film using a bar coater. It apply | coated at 14 mL / m < ² > and it was made to retain for 10 second under the steam type far-infrared heater (made by Noritake Co., Ltd.) heated at 110 degreeC. Subsequently, 3 mL / m 2 of pure water was applied using the same bar coater. Next, washing with a fountain coater and draining with an air knife were repeated three times, and then the saponified cellulose acylate film was produced by staying in a drying zone at 70 ° C. for 5 seconds and drying.
Composition of alkaline solution:
Potassium hydroxide 4.7 parts by weight of water 15.7 parts by mass Isopropanol 64.8 parts by mass Surfactant _{(C 16 H 33 (CH 2} CH 2 O) 10 H) 1.0 parts by mass Propylene glycol 14.9 parts by mass

1- (2) Formation of Alignment Film On the saponified surface of the cellulose acetate film, a coating liquid for forming an alignment film having the composition shown below is applied with a wire bar coater at 24 mL / m 2 and dried with hot air at 100 ° C. for 120 seconds. did. Next, the alignment film surface was rubbed in parallel with the longitudinal direction (conveying direction) of the film.
Composition of alignment film forming coating solution:
-28 parts by mass of modified polyvinyl alcohol shown below-Citric acid ester (AS3, manufactured by Sankyo Chemical Co., Ltd.) 1.2 parts by mass-Photoinitiator (Ilquagua 2959, manufactured by Ciba Japan) 0.84 parts by mass-Glutaraldehyde 2.8 Parts by mass, water, 699 parts by mass, methanol, 226 parts by mass

1- (3) Preparation of Coating Liquid for Curable Liquid Crystal Composition A coating liquid for a curable liquid crystal composition having the following composition was prepared.
Curable liquid crystal composition coating solution composition:
DLC1 95% by mass shown below
DLC2 5% by mass shown below
Fluoroaliphatic group-containing polymer 1 shown below 0.64% by mass
Fluoroaliphatic group-containing polymer 2 shown below 0.16% by mass
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Japan Co., Ltd.) 2.25% by mass
Sensitizer (Kaya Cure DETX, manufactured by Nippon Kayaku Co., Ltd.) 2.25% by mass
Α-Alkylamine shown in the following table Amount shown in the following table Methyl ethyl ketone 382.6% by mass

1- (4) Formation of Optically Anisotropic Layer Each curable liquid crystal composition coating solution was applied to the rubbing-treated surface of the alignment film on the cellulose acetate film with a wire bar coater. Then, it heated for 120 second in a 120 degreeC thermostat, and orientated the liquid crystalline composition. Next, the coating layer of the curable liquid crystal composition is irradiated with ultraviolet rays through a filter (WG280, manufactured by SCHOTT) with the coating layer temperature maintained at 80 ° C., and the polymerization reaction proceeds to change the alignment state. The optically anisotropic layer was formed by fixing. The used filter is a filter having a transmittance of 0% at a wavelength of 185 nm, a transmittance of 0% at a wavelength of 254 nm, and a transmittance of 80% at a wavelength of 300 nm. In addition, a metal halide lamp having an arc tube made of ordinary quartz glass (quartz glass having a transmittance of 7% at a wavelength of 185 nm and a transmittance of 90% at a wavelength of 300 nm) was used for ultraviolet irradiation. The oxygen concentration at the time of ultraviolet irradiation was 20% (200,000 ppm). The illuminance at 365 nm of the ultraviolet light transmitted through the filter was 220 mW / cm ² and the irradiation amount was 350 mJ / cm ² .
The thickness of the formed optically anisotropic layer and the in-plane retardation Re (550) at a wavelength of 550 nm are shown in the following table.
Thus, the optical film which has the optically anisotropic layer which consists of each curable liquid-crystal composition coating liquid was produced, and the following evaluation was performed.

2. Evaluation of Optical Film Each of the produced optical films was immersed in a 1.5 mol / L sodium hydroxide aqueous solution at a temperature of 55 ° C. for 2 minutes, and then the sodium hydroxide was sufficiently washed away with water. Then, after being immersed in a 0.05 mol / L dilute sulfuric acid aqueous solution at a temperature of 35 ° C. for 1 minute, the dilute sulfuric acid aqueous solution was sufficiently washed away by immersing in water, and finally sufficiently dried at 120 ° C.
Before and after the alkaline solution treatment, the thickness of the optically anisotropic layer, the contact angle of the surface, and the in-plane retardation Re (550) at a wavelength of 550 nm were measured, and the results are summarized in the following table. Re (550) is a value calculated and measured using KOBRA 21ADH (manufactured by Oji Scientific Instruments) as described in Japanese Patent Application Laid-Open No. 2007-155942. In addition, Re (550) of only the optically anisotropic layer was calculated by subtracting the contribution of the cellulose acetate film.

From the results shown in the above table, the optically anisotropic layer composed of a curable liquid crystal composition containing an α-alkylamine has a small decrease in film thickness and a decrease in Re due to the alkali solution treatment, and also after the alkali treatment solution. It can be seen that a high contact angle is maintained.
On the other hand, in Comparative Example 2 in which a thiol polymerization accelerator was added instead of the alkali resistance improving agent of the present invention, and in Comparative Example 3 in which a hindered amine antioxidant was added, an alkali resistance improving effect was not obtained.

  Examples of Group I α-alkylamines are N, N-diethylaniline and N-phenylglycine, examples of Group II α-alkylamines are 2-aminoethanol and N-methyldiethanolamine, and III As examples of the α-alkylamines in the group, graphs plotting changes in film thickness with respect to the addition amount of tribenzylamine are shown in FIGS. Other α-alkylamines belonging to each group also showed the same tendency.

3. Production and evaluation of TN mode liquid crystal display device 3- (1) Production of polarizing plate A polyvinyl alcohol (PVA) film having a thickness of 80 μm was immersed in an aqueous iodine solution having an iodine concentration of 0.05 mass% at 30 ° C. for 60 seconds. The sample was dyed and then longitudinally stretched to 5 times the original length while being immersed in an aqueous boric acid solution having a boric acid concentration of 4% by mass for 60 seconds. Then, it was dried at 50 ° C. for 4 minutes to obtain a polarizing film having a thickness of 20 μm.
The back surface of the cellulose acetate film of the optical film of each example saponified with the alkaline solution (the surface on which the optically anisotropic layer is not formed) is used as one surface of this polarizing film using a PVA adhesive. And a commercially available cellulose acetate film that had been subjected to the same saponification treatment with an alkali solution as described above was bonded to the other surface of the polarizing film using a PVA adhesive to obtain a polarizing plate. Fujitac TF80UL (manufactured by FUJIFILM Corporation) was used as a commercially available cellulose acetate film.
Thus, the polarizing plate which has each optical film was produced, respectively.
Using the optical film produced in Comparative Example 1, a polarizing plate for Comparative Example was produced in the same manner.

3- (2) Production of TN-mode liquid crystal display device A pair of polarizing plates provided in a liquid crystal display device (AL2216W, manufactured by Nippon Acer) using a TN mode liquid crystal cell is peeled off, and each polarization produced above is used instead. The plates were attached one by one to the viewer side and the backlight side through an adhesive with the optically anisotropic layer side of the liquid crystal cell. The polarizer was arranged so that the absorption axis of the polarizing plate on the observer side and the absorption axis of the polarizing plate on the backlight side were orthogonal to each other. In this way, a TN mode liquid crystal display device having each polarizing plate was produced.

3- (3) Evaluation Results When the viewing angle region having a contrast of 100 or more was evaluated for each of the produced liquid crystal display devices, all of the liquid crystal display devices including the polarizing plate having the optical film of the example were Comparative Example 1. Compared with the liquid crystal display device provided with the polarizing plate having the optical film, a result having a clearly wide viewing angle region was obtained.

4). Production of Optical Film A coating liquid of a curable liquid crystal composition having the following composition was prepared.
Curable liquid crystal composition coating solution composition:
DLC1 95% by mass
DLC2 5% by mass
The fluoro aliphatic group-containing polymer 1 0.64% by mass
The fluoroaliphatic group-containing polymer 2 0.16% by mass
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Japan Co., Ltd.) 2.25% by mass
Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) Amounts shown in the table below N-phenylglycine 0.75% by mass
Methyl ethyl ketone 382.6% by mass

An optical film was produced in the same manner as in the above example except that each prepared coating solution was used. Further, in the same manner as above, each optical film was treated with an alkaline solution, and the change in film thickness before and after that was measured. Further, scratch resistance was also evaluated by the following method. In general, for use as a member of a liquid crystal display device, it is desired that the scratch resistance of the optically anisotropic layer is 33 g or more.
Method for measuring scratch resistance:
Using a continuous load type scratch strength tester (manufactured by Shinto Kagaku Co., Ltd.) Type 18, while increasing the load continuously with a diamond needle (0.025 mm diameter), the coated surface of the optical film at a speed of 300 mm / min Then, the load value at the point where scratches on the coated film surface began to be scratched was measured as the scratch resistance value.
The results are shown in the table below.

  From the results shown in the above table, it can be understood that increasing the addition amount of the sensitizer increases the strength of the optically anisotropic layer, but decreases the alkali resistance. When the addition amount of N-phenylglycine is 0.3 to 1.5 in terms of molar ratio with respect to the addition amount of the sensitizer, an optically anisotropic layer having sufficient strength and high alkali resistance can be obtained. Can understand.

5. Preparation and Evaluation of Optical Film A coating liquid of a curable liquid crystal composition having the following composition was prepared.
Curable liquid crystal composition coating solution composition:
DLC1 95% by mass
DLC2 5% by mass
The fluoro aliphatic group-containing polymer 1 0.64% by mass
The fluoroaliphatic group-containing polymer 2 0.16% by mass
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Japan Co., Ltd.) Amount shown in the table below Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) Amount shown in the table below N-phenylglycine 0.75% by mass
Methyl ethyl ketone 382.6% by mass

  An optical film was produced in the same manner as in the above example except that each prepared coating solution was used. Further, in the same manner as above, each optical film was treated with an alkaline solution, and the change in film thickness before and after that was measured. Moreover, scratch resistance was also evaluated by the same method as described above. The results are shown in the table below.

  From the results shown in the above table, it can be understood that when the total amount of the polymerization initiator and the sensitizer is increased, the strength of the optically anisotropic layer is improved, while the alkali resistance is lowered. In the above example using N-phenylglycine, the total addition amount of the polymerization initiator and the sensitizer is 0.89 to 5.33% by mass, particularly with sufficient strength and high alkali resistance. It can be understood that an optically anisotropic layer is obtained.

6). Preparation and Evaluation of Optical Film A coating liquid of a curable liquid crystal composition having the following composition was prepared.
Curable liquid crystal composition coating solution composition:
The amount shown in the table below for the DLC1 The amount shown in the table for the DLC2 The polymer containing the fluoroaliphatic group 1 0.64% by mass
The fluoroaliphatic group-containing polymer 2 0.16% by mass
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Japan Co., Ltd.) 2.25% by mass
Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.75% by mass
N-phenylglycine 0.75% by mass
Methyl ethyl ketone 382.6% by mass

  An optical film was produced in the same manner as in the above example except that each prepared coating solution was used. Further, in the same manner as above, each optical film was treated with an alkaline solution, and the change in film thickness before and after that was measured. Further, in the same manner as described above, Re at a wavelength of 450 nm and Re at a wavelength of 550 nm were measured for each optically anisotropic layer, and Re (450) / Re (550), which is an index indicating wavelength dispersion characteristics, was calculated. Note that ideal chromatic dispersion characteristics in optical compensation are Re (450) / Re (550) = 1.53 to 1.70. The results are shown in the table below.

  From the results shown in the above table, it can be understood that when the ratio of DLC1 is increased, preferable characteristics can be obtained not only from the viewpoint of wavelength dispersion characteristics but also from the viewpoint of alkali resistance.

7). Preparation and Evaluation of Optical Film A coating liquid of a curable liquid crystal composition having the following composition was prepared.
Curable liquid crystal composition coating solution composition:
DLC1 (any of DLC1a to DLC1d shown below) 95.0% by mass
DLC2 5.0 mass%
The fluoro aliphatic group-containing polymer 1 0.64% by mass
The fluoroaliphatic group-containing polymer 2 0.16% by mass
Photopolymerization initiator (Irgacure 907, manufactured by Ciba Japan Co., Ltd.) 2.25% by mass
Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.75% by mass
N-phenylglycine 0.75% by mass
Methyl ethyl ketone 382.6% by mass

  An optical film was produced in the same manner as in the above example except that each prepared coating solution was used. Further, in the same manner as above, each optical film was treated with an alkaline solution, and the change in film thickness before and after that was measured.

  From the results shown in the above table, it can be understood that the longer the side chain alkylene chain, the more the alkali resistance is improved.

Claims (17)

An alkali resistance improver for a curable composition comprising at least one α-alkylamine. The alkali resistance improving agent for a curable composition according to claim 1, wherein the α-alkylamine is an α-alkylamine having an aromatic ring directly bonded to a nitrogen atom. The alkali resistance improver for a curable composition according to claim 1, wherein the α-alkylamine is an aliphatic α-alkylamine. The alkali resistance improver for curable compositions according to claim 1, wherein the α-alkylamine is an α-alkylamine containing an aromatic ring bonded to a nitrogen atom via a linking group. The alkali resistance improver for a curable composition according to claim 1, wherein the α-alkylamine is a tertiary amine bonded to a nitrogen atom. A curable liquid crystal composition containing at least one polymerization initiator, at least one polymerizable liquid crystal compound, and at least the alkali resistance improver according to any one of claims 1 to 5. The one or more polymerizable liquid crystal compounds have a discotic core and two or more side chains bonded to atoms constituting the discotic core, and the side chains have an ester bond. 6. The curable liquid crystal composition according to 6. The at least one polymerizable liquid crystal compound has a disk-shaped core and two or more side chains bonded to atoms constituting the disk-shaped core, and the side chain has one oxadiazole ring. The curable liquid crystal composition according to claim 6 or 7 having the above. The one or more polymerizable liquid crystal compounds are 1,3,5-substituted benzene derivatives or 1,2,7,8,13,14-substituted triphenylene derivatives, according to any one of claims 6 to 8. The curable liquid crystal composition described. The alkali resistance improver is contained in a molar ratio of 0.1 × 10 ^{2 to} 2.0 × 10 ² with respect to the one or more polymerizable liquid crystal compounds. The curable liquid crystal composition described in 1. Furthermore, at least 1 sort (s) of sensitizers are contained, The said alkali tolerance improver is contained in the ratio of 0.1-1.5 by molar ratio with respect to the said sensitizer. The curable liquid crystal composition according to item. The curable liquid crystal composition according to any one of claims 6 to 11, further comprising at least one sensitizer, and 0.1 to 10% by mass in total of the polymerization initiator and the sensitizer. object. The optical film which has a polymer film and the optically anisotropic layer formed by hardening | curing the curable liquid crystalline composition of any one of Claims 6-12 on this polymer film. The optical film according to claim 13, wherein a contact angle of the surface of the optically anisotropic layer after the alkali solution treatment is 60 to 95 °. The optical film according to claim 13 or 14, which has been subjected to an alkali saponification treatment. A polarizing plate comprising the optical film according to claim 13 and a polarizing film. A liquid crystal display device comprising the optical film according to any one of claims 13 to 15 and / or the polarizing plate according to claim 16.

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