JP6675049B1 - Polymerizable liquid crystal composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymerizable liquid crystal composition capable of suppressing the occurrence of alignment defects and unevenness of film thickness of a liquid crystal cured film obtained even after long-term storage. A polymerizable liquid crystal composition containing a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent, wherein 0.15 ≦ cV ≦ 0.65, where cV is a polymerizable liquid crystal. The solid content concentration c (mass fraction) of the composition and the viscosity V (mPa · s) of the polymerizable liquid crystal composition at 23 ° C. 48 hours after the completion of mixing all the components contained in the polymerizable liquid crystal composition Which represents the product of]. [Selection diagram] None

Description

  The present invention is a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent, a liquid crystal cured film obtained by curing the polymerizable liquid crystal composition, a retardation film including the liquid crystal cured film, The present invention relates to an elliptically polarizing plate including a retardation film and a polarizing film, and a display device including the elliptically polarizing plate.

  An optical film such as a polarizing film or a retardation film is used for a flat panel display (FPD). In recent years, a retardation film including a liquid crystal cured film obtained by curing a polymerizable liquid crystal composition including a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent has been known from the viewpoint of thinning (for example, JP-A-2017-2017). No. 027058).

JP 2017-027058 A

  In order to continuously form such a cured liquid crystal film, it is necessary to prepare the polymerizable liquid crystal composition and store it for a long time. However, according to the study of the present inventor, when the polymerizable liquid crystal composition is stored for a long period of time, the polymerizable liquid crystal compound in the composition reacts due to the influence of light, and gelation proceeds. In addition, it was found that when the polymerizable liquid crystal compound was polymerized in an aligned state after storage, an alignment defect of the obtained liquid crystal cured film might occur. It was also found that even if the gelling of the polymerizable liquid crystal compound did not proceed, when the liquid crystal cured film was formed after storage, the film thickness might become uneven.

  Accordingly, an object of the present invention is to provide a polymerizable liquid crystal composition capable of suppressing the occurrence of alignment defects and unevenness in film thickness of a liquid crystal cured film obtained even after long-term storage, and to cure the polymerizable liquid crystal composition. Liquid crystal cured film, a retardation film including the liquid crystal cured film, an elliptically polarizing plate including the retardation film and the polarizing film, and a display device including the elliptically polarizing plate.

  The present inventors have conducted intensive studies to solve the above-described problems, and as a result, in a polymerizable liquid crystal composition including a polymerizable liquid crystal composition, a polymerization initiator, and an organic solvent, the solid content concentration c ( The product of the mass fraction) and the viscosity V (mPa · s) at 23 ° C. of the polymerizable liquid crystal composition 48 hours after the completion of mixing all the components contained in the composition is 0.15 or more and 0.65 or more. In the following, the inventors have found that the above problems can be solved, and have completed the present invention. That is, the present invention includes the following.

[1] A polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent,
The following equation (1)
0.15 ≦ cV ≦ 0.65 (1)
[In the formula, cV is the solid content concentration c (mass fraction) of the polymerizable liquid crystal composition, and 23 ° C. of the polymerizable liquid crystal composition 48 hours after completion of mixing all the components contained in the polymerizable liquid crystal composition. With the viscosity V (mPa · s) at
A polymerizable liquid crystal composition that satisfies the following.
[2] The polymerizable liquid crystal composition according to [1], wherein the polymerizable liquid crystal compound is a liquid crystal compound having a photopolymerizable group.
[3] The polymerizable liquid crystal composition according to [1] or [2], wherein the polymerization initiator has a maximum absorption wavelength of 300 to 400 nm.
[4] The polymerizable liquid crystal composition according to any one of [1] to [3], wherein the polymerizable liquid crystal compound has a maximum absorption wavelength of 300 to 400 nm.
[5] The polymerizable liquid crystal composition according to any one of [1] to [4], further comprising a polymerization inhibitor.
[6] The polymerizable liquid crystal composition according to [5], wherein the content of the polymerization inhibitor is 0.1 to 10 parts by mass with respect to 100 parts by mass of the polymerizable liquid crystal compound.
[7] The polymerizable liquid crystal composition according to [5] or [6], wherein the polymerization inhibitor is a primary antioxidant.
[8] A cured liquid crystal film obtained by curing the polymerizable liquid crystal composition according to any one of [1] to [7], wherein the polymerizable liquid crystal compound is polymerized in an aligned state.
[9] A retardation film comprising the liquid crystal cured film according to [8].
[10] An elliptically polarizing plate comprising the retardation film according to [9] and a polarizing film.
[11] A display device including the elliptically polarizing plate according to [10].

  The polymerizable liquid crystal composition of the present invention can suppress the occurrence of alignment defects and unevenness in the thickness of a cured liquid crystal film even after long-term storage.

[Polymerizable liquid crystal composition]
The polymerizable liquid crystal composition of the present invention contains a polymerizable liquid crystal composition, a polymerization initiator, and an organic solvent, and has the following formula (1)
0.15 ≦ cV ≦ 0.65 (1)
[In the formula, cV is the solid content concentration c (mass fraction) of the polymerizable liquid crystal composition, and 23 ° C. of the polymerizable liquid crystal composition 48 hours after completion of mixing all the components contained in the polymerizable liquid crystal composition. With the viscosity V (mPa · s) at
Satisfy the relationship. Surprisingly, when the relationship of the expression (1) is satisfied, it is possible to suppress the occurrence of alignment defects and unevenness in the thickness of the obtained liquid crystal cured film even after long-term storage. Therefore, a liquid crystal cured film obtained by curing the polymerizable liquid crystal composition of the present invention can have excellent orientation and a uniform film thickness. On the other hand, when the cV is less than 0.15, unevenness in the thickness of the obtained liquid crystal cured film may occur. When cV exceeds 0.65, alignment defects of the obtained cured liquid crystal film may occur.

In the formula (1), the solid content of the polymerizable liquid crystal composition means all components except volatile components such as an organic solvent in the polymerizable liquid crystal composition, and the solid content concentration c (mass fraction) The term “solid content” refers to the content of the solid content with respect to the mass of the polymerizable liquid crystal composition, and is a value obtained by dividing the mass of the solid content contained in the polymerizable liquid crystal composition by the mass of the polymerizable liquid crystal composition.
The solid content concentration c (mass fraction) of the polymerizable liquid crystal composition is not limited as long as the formula (1) is satisfied, but is preferably 0.01 to 0.5, more preferably 0.03 to 0.3, and furthermore It is preferably from 0.05 to 0.25, particularly preferably from 0.07 to 0.15. When the solid content concentration c is in the above range, good coatability of the polymerizable liquid crystal composition is obtained, and it is easy to suppress the occurrence of unevenness in the thickness of the obtained cured liquid crystal film.

In the formula (1), the viscosity V indicates the viscosity (mPa · s) at 23 ° C. of the polymerizable liquid crystal composition 48 hours after the completion of mixing all the components contained in the polymerizable liquid crystal composition. As a method for mixing the polymerizable liquid crystal composition, for example, stirring and the like can be mentioned. The time when 48 hours have elapsed after the completion of the mixing means the time when 48 hours have elapsed since the end of the mixing, for example, the stirring. The storage from the end of mixing to the lapse of 48 hours is performed in a closed container under a 23 ° C. fluorescent lamp (40 W).
The viscosity V is not limited as long as the formula (1) is satisfied, but is preferably 1 to 15 mPa · s, more preferably 1 to 10 mPa · s, and still more preferably 1 to 5 mPa · s. When the viscosity V is equal to or more than the above lower limit, it is easy to suppress the occurrence of unevenness in the thickness of the obtained liquid crystal cured film, and when the viscosity V is equal to or less than the above upper limit, the occurrence of alignment defects in the obtained liquid crystal cured film is suppressed. It's easy to do.

  In the formula (1), cV, which is the product of c and V, is preferably 0.17 to 0.60, and more preferably 0.20 to 0.57. When the cV is equal to or more than the above lower limit, it is easy to suppress the occurrence of unevenness in the thickness of the obtained liquid crystal cured film, and when the cV is equal to or less than the above upper limit, the occurrence of alignment defects in the obtained liquid crystal cured film is suppressed. Cheap. In addition, when the obtained liquid crystal cured film is a retardation film, if the liquid crystal cured film has unevenness in film thickness, unevenness in retardation may occur. Therefore, it can be said that the occurrence of the unevenness of the film thickness can be suppressed, and the occurrence of the unevenness of the phase difference can be suppressed, but the unevenness of the film thickness is, for example, the unevenness of the phase difference of the liquid crystal cured film as described in the examples. It can be evaluated by measuring.

<Polymerizable liquid crystal compound>
The polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition of the present invention means a liquid crystal compound having a polymerizable group, particularly a photopolymerizable group. Known polymerizable liquid crystal compounds can be used. The photopolymerizable group means a group that can participate in a polymerization reaction by a reactive species generated from a photopolymerization initiator, for example, an active radical or an acid. Examples of the photopolymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, but is preferably a thermotropic liquid crystal in that the film thickness can be precisely controlled. The phase order structure of the thermotropic liquid crystal may be a nematic liquid crystal or a smectic liquid crystal. The polymerizable liquid crystal compounds can be used alone or in combination of two or more.

Examples of the polymerizable liquid crystal compound include compounds satisfying all of the following (1) to (4).
(1) a compound capable of forming a nematic phase;
(2) The polymerizable liquid crystal compound has π electrons on the major axis direction (a).
(3) π electrons are present in a direction (cross direction (b)) intersecting with the long axis direction (a).
(4) A polymerizable liquid crystal compound defined by the following formula (i), where N (πa) is the total of π electrons present in the major axis direction (a), and N (Aa) is the total of molecular weights present in the major axis direction. Π electron density in the major axis direction (a):
D (πa) = N (πa) / N (Aa) (i)
And a polymerizable liquid crystal compound defined by the following formula (ii), where N (πb) is the total of π electrons present in the cross direction (b), and N (Ab) is the total of molecular weights present in the cross direction (b). Electron density in the cross direction (b) of
D (πb) = N (πb) / N (Ab) (ii)
And
0 ≦ [D (πa) / D (πb)] ≦ 1
[That is, the π electron density in the cross direction (b) is larger than the π electron density in the long axis direction (a)].
The polymerizable liquid crystal compound satisfying all of the above (1) to (4) can form a nematic phase by being applied on an alignment film and heated to a phase transition temperature or higher. In a nematic phase formed by aligning the polymerizable liquid crystal compound, the polymerizable liquid crystal compound is usually aligned such that the major axes thereof are parallel to each other, and the major axis is the alignment direction of the nematic phase.

で表される化合物が挙げられる。 In general, the polymerizable liquid crystal compound having the above characteristics generally shows reverse wavelength dispersion. Specific examples of the compound satisfying the above properties (1) to (4) include, for example, the following formula (I):

The compound represented by these is mentioned.

In the formula (I), Ar represents a divalent aromatic group which may have a substituent. The aromatic group referred to here is a group having a planar structure with a cyclic structure, and the cyclic structure has [4n + 2] π electrons according to the Huckel rule. Here, n represents an integer. When a ring structure is formed including a hetero atom such as -N = or -S-, the case where the compound has aromaticity by satisfying the Huckel rule, including a non-covalent bond electron pair on the hetero atom, is also included. The divalent aromatic group preferably contains at least one of a nitrogen atom, an oxygen atom, and a sulfur atom.
G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, a hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group is a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, The carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an alkoxy group, a cyano group or a nitro group of the formulas 1 to 4, and is an oxygen atom, a sulfur atom Alternatively, it may be substituted by a nitrogen atom.
L ¹ , L ² _, B ¹ and B ² are each independently a single bond or a divalent linking group.
k and l each independently represent an integer of 0 to 3, and satisfy the relationship of 1 ≦ k + 1. Here, when 2 ≦ k + 1, B ¹ and B ² , G ¹ and G ² may be the same as or different from each other.
E ¹ and E ² each independently represent an alkanediyl group having 1 to 17 carbon atoms, wherein a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, is, -O - - _-CH 2 contained, - S -, - it may be substituted with Si-.
P ¹ and P ² independently represent a polymerizable group or a hydrogen atom, and at least one is a polymerizable group.

G ¹ and G ² are each independently preferably a 1,4-phenylenediyl group optionally substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms. A 1,4-cyclohexanediyl group optionally substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably 1-cyclohexanediyl group substituted with a methyl group , 4-phenylenediyl group, unsubstituted 1,4-phenylenediyl group or unsubstituted 1,4-trans-cyclohexanediyl group, particularly preferably unsubstituted 1,4-phenylenediyl group or unsubstituted 1,4-phenylenediyl group. It is a substituted 1,4-trans-cyclohexanediyl group.
Further, at least one of a plurality of G ¹ and G ² is preferably a divalent alicyclic hydrocarbon group, and at least one of G ¹ and G ² bonded to L ¹ or L ^2. One is more preferably a divalent alicyclic hydrocarbon group.

L ¹ and L ² are preferably each independently a single bond, an alkylene group having 1 to 4 carbon atoms, —O—, —S—, —R ^a1 OR ^a2 —, —R ^a3 COOR ^a4- , —R ^{a5 OCOR a6 -, R a7 OC =} OOR a8 -, - N = N -, - CR c = CR d -, or C≡C-. Here, R ^{a1 to} R ^a8 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms, and R ^c and R ^d each represent an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L ¹ and L ² are each independently more preferably a single bond, —OR ^a2-1 —, —CH ₂ —, —CH ₂ CH ₂ —, ^{—COOR a4-1} —, or OCOR ^a6-1 —. . ^{Wherein, R a2-1, R a4-1, R} a6-1 each independently a single _{bond, -CH 2 -, - CH 2} CH 2 - represents either. L ¹ and L ² are each independently more preferably a single bond, —O—, —CH ₂ CH ₂ —, —COO—, —COOCH ₂ CH ₂ —, or OCO—.

B ¹ and B ² are preferably each independently a single bond, an alkylene group having 1 to 4 carbon atoms, —O—, —S—, —R ^a9 OR ^a10 —, —R ^a11 COOR ^a12 —, and —R ^a13. OCOR ^a14 − or R ^a15 OC = OOR ^a16 −. Here, R ^{a9 to} R ^a16 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms. B ¹ and B ² are each independently preferably a single bond, —OR ^a10-1 —, —CH ₂ —, —CH ₂ CH ₂ —, ^{—COOR a12-1} —, or OCOR ^a14-1 —. . ^{Wherein, R a10-1, R a12-1, R} a14-1 each independently a single _{bond, -CH 2 -, - CH 2} CH 2 - represents either. B ¹ and B ² are each independently, more preferably, a single bond, —O—, —CH ₂ CH ₂ —, —COO—, —COOCH ₂ CH ₂ —, —OCO—, or OCOCH ₂ CH ₂ —. .

  k and l are preferably in the range of 2 ≦ k + 1 ≦ 6, preferably k + 1 = 4, and more preferably k = 2 and l = 2, from the viewpoint of developing reverse wavelength dispersion. It is preferable that k = 2 and l = 2 because a symmetric structure is obtained.

E ¹ and E ² are each independently preferably an alkanediyl group having 1 to 17 carbon atoms, more preferably an alkanediyl group having 4 to 12 carbon atoms.

Examples of the polymerizable group represented by P ¹ or P ² include an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, and an oxiranyl group. And an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group and an oxetanyl group are preferable, and an acryloyloxy group is more preferable.

  Ar preferably has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring, and a benzene ring and a naphthalene ring are preferable. Examples of the aromatic heterocycle include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, and a pyrazole ring. Thiazole ring, benzothiazole ring, thienothiazole ring, oxazole ring, benzoxazole ring, and phenanthroline ring. Among them, a thiazole ring, a benzothiazole ring, or a benzofuran ring is preferable, and a benzothiazole group is more preferable. When Ar contains a nitrogen atom, the nitrogen atom preferably has π electrons.

Wherein (I), 2-valent of [pi Total N _[pi electrons contained in the aromatic group is preferably 8 or more represented by Ar, more preferably 10 or more, more preferably 14 or more, particularly Preferably it is 16 or more. Further, it is preferably 30 or less, more preferably 26 or less, and further preferably 24 or less.

  Examples of the aromatic group represented by Ar include the following groups.

In the formulas (Ar-1) to (Ar-23), an asterisk (*) represents a connecting part, and Z ⁰ , Z ¹ and Z ² each independently represent a hydrogen atom, a halogen atom, or an alkyl having 1 to 12 carbons. Group, cyano group, nitro group, alkylsulfinyl group having 1 to 12 carbon atoms, alkylsulfonyl group having 1 to 12 carbon atoms, carboxyl group, fluoroalkyl group having 1 to 12 carbon atoms, alkoxy group having 1 to 6 carbon atoms, An alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N, N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms or carbon Represents an N, N-dialkylsulfamoyl group of Formulas 2 to 12.

Q ^{1, Q 2} and ^{Q 3} are, each ^{independently, -CR 2 'R 3' -} , - S -, - NH -, - NR 2 '-, - represents CO- or O- a, R ^2' and R ^{3 ′} each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J ¹ and J ² each independently represent a carbon atom or a nitrogen atom.

Y ¹ , Y ² and Y ³ each independently represent an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group.

W ¹ and W ² each independently represent a hydrogen atom, a cyano group, a methyl group or a halogen atom, and m represents an integer of 0 to 6.

Examples of the aromatic hydrocarbon group for Y ¹ , Y ² and Y ³ include an aromatic hydrocarbon group having 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group and a biphenyl group. , A naphthyl group is preferred, and a phenyl group is more preferred. The aromatic heterocyclic group includes a nitrogen atom such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, a benzothiazolyl group, a heteroatom such as an oxygen atom or a sulfur atom, and has 4 to 20 carbon atoms. An aromatic heterocyclic group is mentioned, and a furyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group are preferable.

Y ¹ , Y ² and Y ³ may each independently be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

Preferably, Z ⁰ , Z ¹ and Z ² are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, or an alkoxy group having 1 to 12 carbon atoms. ⁰ is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, and a cyano group, and Z ¹ and Z ² are more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, and a cyano group.

Q ¹ , Q ² and Q ³ are preferably -NH-, -S-, -NR ^{2 '} -and -O-, and R ^2' is preferably a hydrogen atom. Among them, -S-, -O-, and -NH- are particularly preferable.

Among the formulas (Ar-1) to (Ar-23), the formulas (Ar-6) and (Ar-7) are preferable from the viewpoint of molecular stability.
In the formulas (Ar-16) to (Ar-23), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ⁰ . Examples of the aromatic heterocyclic group include those described above as the aromatic heterocyclic ring which Ar may have, for example, a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole Ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring and the like. This aromatic heterocyclic group may have a substituent. In addition, Y ¹ may be the above-mentioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ⁰ . For example, a benzofuran ring, a benzothiazole ring, a benzoxazole ring and the like can be mentioned.

  Among the polymerizable liquid crystal compounds, a polymerizable liquid crystal compound having a maximum absorption wavelength of 300 to 400 nm is preferable. Since the polymerization initiator contained in the polymerizable liquid crystal composition preferably has an absorption wavelength at 300 to 400 nm, more preferably has a maximum absorption wavelength at 300 to 400 nm, the composition absorbs ultraviolet light during storage, and As a result, reactive species such as active radicals are generated, and the polymerization reaction and gelation of the polymerizable liquid crystal compound may proceed. However, as described above, when the polymerizable liquid crystal compound having a maximum absorption wavelength of 300 to 400 nm is contained in the composition, even if the composition is exposed to ultraviolet light during storage, the polymerizable liquid crystal compound absorbs the exposure light, Generation of reactive species by the photopolymerization initiator and progress of polymerization reaction and gelation of the polymerizable liquid crystal compound by the reactive species can be effectively suppressed. Therefore, when a polymerizable liquid crystal compound having a maximum absorption wavelength of 300 to 400 nm is contained in the polymerizable liquid crystal composition, it is advantageous in terms of long-term stability of the polymerizable liquid crystal composition, and the orientation and film orientation of the resulting cured liquid crystal film. The uniformity of thickness can be improved. The maximum absorption wavelength of the polymerizable liquid crystal compound can be measured in a solvent using an ultraviolet-visible spectrophotometer. The solvent is a solvent capable of dissolving the polymerizable liquid crystal compound, and examples thereof include chloroform.

  The content of the polymerizable liquid crystal compound in the polymerizable liquid crystal composition is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass with respect to 100 parts by mass of the solid content of the polymerizable liquid crystal composition. Yes, more preferably 85 to 98 parts by mass, even more preferably 90 to 95 parts by mass. When the content of the polymerizable liquid crystal compound is within the above range, it is advantageous from the viewpoint of the orientation of the obtained cured liquid crystal film. In addition, in this specification, the solid content of a polymerizable liquid crystal composition means all components except volatile components, such as an organic solvent, from a polymerizable liquid crystal composition.

<Polymerization initiator>
The polymerizable liquid crystal composition of the present invention contains a polymerization initiator. The polymerization initiator is a compound capable of generating a reactive species by the contribution of heat or light and initiating a polymerization reaction such as a polymerizable liquid crystal compound. Examples of the reactive species include radicals, cations and anions. Above all, a photopolymerization initiator that generates a radical (active radical) upon irradiation with light is preferred from the viewpoint of easy reaction control.

  Examples of the photopolymerization initiator include benzoin compounds, benzophenone compounds, benzyl ketal compounds, α-hydroxyketone compounds, α-aminoketone compounds, triazine compounds, iodonium salts, and sulfonium salts. Specifically, Irgacure (registered trademark) 907, Irgacure 184, Irgacure 651, Irgacure 819, Irgacure 250, Irgacure 369, Irgacure 379, Irgacure 127, Irgacure 2959, Irgacure 754, Irgacure 379EG (BASF Japan Ltd.) Seikaru BZ, Seikeol Z, Seikeol BEE (manufactured by Seiko Chemical Co., Ltd.), kayacure BP100 (manufactured by Nippon Kayaku Co., Ltd.), Kayacure UVI-6992 (manufactured by Dow), Adeka Optomer SP- 152, Adeka Optomer SP-170, Adeka Optomer N-1717, Adeka Optomer N-1919, Adeka Arculs NCI-831, Adeka Arculs NCI-930 (all stocks) ADEKA), TAZ-A, TAZ-PP (above, manufactured by Nippon Siebel-Hegner) and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.). The photopolymerization initiators can be used alone or in combination of two or more.

The photopolymerization initiator maximizes the absorption from the viewpoint of fully utilizing the energy emitted from the light source, securing a sufficient polymerization rate of the polymerizable liquid crystal compound, and obtaining a liquid crystal cured film having sufficient hardness as a retardation film. The wavelength is preferably from 300 to 400 nm, and more preferably from 300 to 380 nm. On the other hand, when a polymerizable liquid crystal compound having a maximum absorption wavelength of 300 to 400 nm is contained in the composition as described above, generation of a reactive species by the photopolymerization initiator during long-term storage and polymerization by the reactive species The progress of the polymerization reaction and gelation of the liquid crystal compound can be effectively suppressed. From such a viewpoint, a photopolymerization initiator having a maximum absorption wavelength at 300 to 400 nm can be suitably used. The maximum absorption wavelength of the photopolymerization initiator can be measured in a solvent using an ultraviolet-visible spectrophotometer. The solvent is a solvent capable of dissolving the polymerizable liquid crystal compound, and examples thereof include chloroform.
Among the photopolymerization initiators, α-acetophenone-based photopolymerization initiators and oxime-based photopolymerization initiators are preferred.

  Examples of the α-acetophenone-based photopolymerization initiator include 2-methyl-2-morpholino-1- (4-methylsulfanylphenyl) propan-1-one and 2-dimethylamino-1- (4-morpholinophenyl) -2. -Benzylbutan-1-one and 2-dimethylamino-1- (4-morpholinophenyl) -2- (4-methylphenylmethyl) butan-1-one; and more preferably, 2-methyl-2-one. Examples include morpholino-1- (4-methylsulfanylphenyl) propan-1-one and 2-dimethylamino-1- (4-morpholinophenyl) -2-benzylbutan-1-one. Commercially available α-acetophenone-based photopolymerization initiators include Irgacure 369, 379EG, 907 (all manufactured by BASF Japan K.K.) and Sequol BEE (manufactured by Seiko Chemical Co., Ltd.).

  The oxime-based photopolymerization initiator generates a methyl radical when irradiated with light. The polymerization of the polymerizable liquid crystal compound in the deep part of the liquid crystal cured film proceeds favorably by the methyl radical. Further, from the viewpoint of promoting the polymerization reaction in the deep part of the cured liquid crystal film more efficiently, it is preferable to use a photopolymerization initiator capable of efficiently utilizing ultraviolet light having a wavelength of 350 nm or more. As a photopolymerization initiator capable of efficiently utilizing ultraviolet light having a wavelength of 350 nm or more, a triazine compound or an oxime ester-type carbazole compound is preferable, and from the viewpoint of sensitivity, an oxime ester-type carbazole compound is more preferable. Examples of the oxime ester type carbazole compound include 1,2-octanedione, 1- [4- (phenylthio) -2- (O-benzoyloxime)], ethanone, and 1- [9-ethyl-6- (2-methyl). Benzoyl) -9H-carbazol-3-yl] -1- (O-acetyloxime) and the like. Commercially available oxime ester-type carbazole compounds include Irgacure OXE-01, Irgacure OXE-02, Irgacure OXE-03 (all manufactured by BASF Japan Ltd.), Adeka Optomer N-1919, and Adeka Arculs NCI-831 (all And ADEKA Corporation).

  The content of the polymerization initiator can be appropriately adjusted according to the type and the amount of the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition. Is preferably 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass. When the content of the polymerization initiator is equal to or more than the above lower limit, the reaction of the polymerizable group sufficiently proceeds, and the polymerization rate can be increased. When the content of the polymerization initiator is equal to or less than the upper limit, the long-term storage stability of the polymerizable liquid crystal composition is easily improved.

<Organic solvent>
The polymerizable liquid crystal composition of the present invention contains an organic solvent. The organic solvent is preferably a solvent that can dissolve the polymerizable liquid crystal compound and is inert to the polymerization reaction of the polymerizable liquid crystal compound, and may be appropriately selected depending on the polymerizable liquid crystal compound used.
Specifically, for example, alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate; ester solvents such as γ-butyrolactone, propylene glycol methyl ether acetate and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone and methyl isobutyl ketone; aliphatic hydrocarbons such as pentane, hexane and heptane Solvents; Aromatic hydrocarbon solvents such as toluene and xylene; Nitrile solvents such as acetonitrile; Tetrahydro Ether solvents such as orchid and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone And the like. These organic solvents can be used alone or in combination of two or more. Among these, from the viewpoint of film coating, it is preferable to use at least one selected from alcohol solvents, ester solvents, ketone solvents, chlorine-containing solvents, amide solvents and aromatic hydrocarbon solvents, From the viewpoint of solubility, it is more preferable to use at least one selected from ester solvents, ketone solvents, and amide solvents.

  The content of the organic solvent in 100 parts by mass of the polymerizable composition is preferably 50 to 99 parts by mass, more preferably 70 to 97 parts by mass, still more preferably 75 to 95 parts by mass, and particularly preferably 85 to 93 parts by mass. . When the content of the organic solvent is in the above range, good coatability of the polymerizable liquid crystal composition is obtained, and it is easy to suppress the occurrence of unevenness in the thickness of the obtained cured liquid crystal film.

<Polymerization inhibitor>
The polymerizable liquid crystal composition of the present invention preferably contains a polymerization inhibitor. The degree of progress of the polymerization reaction of the polymerizable liquid crystal compound can be controlled by the polymerization inhibitor. Therefore, by adjusting the content of the polymerization inhibitor contained in the composition, the viscosity at 23 ° C. of the polymerizable liquid crystal composition at the time of lapse of 48 hours after the completion of mixing all the components contained in the polymerizable liquid crystal composition. V can be controlled. When the content of the polymerization inhibitor contained in the composition becomes large, the polymerization reaction of the polymerizable liquid crystal compound is suppressed, so that the viscosity V tends to become small. On the other hand, when the content of the polymerization inhibitor contained in the composition is small, the polymerization reaction of the polymerizable liquid crystal compound tends to proceed, so that the viscosity V tends to increase. The viscosity V can be controlled by appropriately adjusting the types and amounts of the organic solvent, the polymerization initiator, and the polymerizable liquid crystal composition.

  As the polymerization inhibitor, a polymerization inhibitor conventionally known in the field of a retardation film can be used. Examples thereof include a phenol-based antioxidant, an amine-based antioxidant, a quinone-based antioxidant, and a nitroso-based antioxidant. Primary antioxidants such as antioxidants; secondary antioxidants such as phosphorus antioxidants and sulfur antioxidants. The polymerization inhibitors can be used alone or in combination of two or more. Among these, a primary antioxidant such as a phenolic antioxidant is preferable from the viewpoint of capturing radicals derived from a polymerization initiator, and a primary oxidation agent having a molecular weight of 500 or less from the viewpoint of not inhibiting polymerization of a cured liquid crystal film after drying. Inhibitors are more preferred.

The phenolic antioxidant is an antioxidant having a phenolic hydroxy group in the molecule, and preferably has an alkyl group at the ortho position of the phenolic hydroxy group. In the present specification, an antioxidant having both a phenolic hydroxy group and a phosphate or phosphite structure is classified as a phosphorus-based antioxidant.
Examples of the phenolic antioxidant include 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4′-butylidene-bis (3-methyl-6- tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 2-tert-butyl-6- (3-tert -Butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, (tetrakis [methylene-3- (3,5-di-tet-butyl-4-hydroxyphenyl) propionate] methane, pentaerythritol tetrakis [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-a, a ′, a ″-(mesitylene -2,4,6-triyl) tri-p-cresol, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4 , 6 (1H, 3H, 5H) -trione, 1,3,5-tris ((4-tert-butyl-3-hydroxy-2,6-xylyl) methyl) -1,3,5-triazine-2, 4,6 (1H, 3H, 5H) -trione, thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], benzenepropanoic acid, 3,5-bis (1, 1-dimethylethyl) -4-hydroxy, C7 C9 side chain alkyl ester, 4,6-bis (octylthiomethyl) -o-cresol, Irganox (registered trademark) 3125 (manufactured by BASF), 2,4-bis (n-octylthio) -6- (4-hydroxy 3 ', 5'-di-tert-butylanilino) -1,3,5-triazine, 3,9-bis (2- (3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy ) -1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro (5,5) undecane, dibutylhydroxytoluene (2,6-di-tert-butyl-p-cresol, BHT) Sumitizer (registered trademark) BHT (Sumitomo Chemical Co., Ltd.), Sumilizer (registered trademark) GA-80 (Sumitomo Chemical Co., Ltd.), Sumilizer (registered trademark) (Registered trademark) GS (manufactured by Sumitomo Chemical Co., Ltd.), Cyanox (registered trademark) 1790 (manufactured by Cytec), and vitamin E (manufactured by Eisai Co., Ltd.).

  The amine antioxidant is an antioxidant having an amino group in the molecule. Examples of the amine antioxidant include 1-naphthylamine, phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine, p-nonylphenyl-1-naphthylamine, p-dodecylphenyl-1-naphthylamine, and phenyl-2. A naphthylamine-based antioxidant such as naphthylamine; N, N'-diisopropyl-p-phenylenediamine, N, N'-diisobutyl-p-phenylenediamine, N, N'-diphenyl-p-phenylenediamine, N, N ' -Di-β-naphthyl-p-phenylenediamine, N-phenyl-N′-isopropyl-p-phenylenediamine, N-cyclohexyl-N′-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N '-Phenyl-p-phenylenediamine, dioctyl-p Phenylenediamine antioxidants such as phenylenediamine, phenylhexyl-p-phenylenediamine, phenyloctyl-p-phenylenediamine; dipyridylamine, diphenylamine, p, p'-di-n-butyldiphenylamine, p, p'-di -Tert-butyldiphenylamine, p, p'-di-tert-pentyldiphenylamine, p, p'-dioctyldiphenylamine, p, p'-dinonyldiphenylamine, p, p'-didecyldiphenylamine, p, p'-di Diphenyls such as dodecyldiphenylamine, p, p'-distyryldiphenylamine, p, p'-dimethoxydiphenylamine, 4,4'-bis (4-α, α-dimethylbenzoyl) diphenylamine, p-isopropoxydiphenylamine and dipyridylamine Triethanolamine antioxidants; phenothiazine, N- methyl phenothiazine, N- ethylphenothiazine, 3,7-dioctylphenothiazine, phenothiazine carboxylate ester, phenothiazine-based antioxidants such as phenol Serena gin and the like.

  The phosphorus-based antioxidant is an antioxidant having a phosphate ester structure or a phosphite ester structure. Examples of the phosphorus-based antioxidant include 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butyldibenz [d, f] [1,3,2] dioxaphosphepin, tris (2,4-di-tert-butylphenyl) phosphite, diphenylisooctylphosphite, 2,2′-methylenebis (4,6-di- (tert-butylphenyl) octylphosphite, diphenylisodecylphosphite, diphenylisodecylphosphite, triphenylphosphate, tributylphosphate, distearylpentaerythritol diphosphite, cyclic neopentanetetraylbis (2,6- Di-tert-butyl-4-methylphenyl Phosphite, 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butylbenzo [d, f] [1,3 2] dioxaphosphepin, tris (nonylphenyl) phosphite, tris (mono- & dinonylphenyl mixed) phosphite, diphenylmono (tridecyl) phosphite, 2,2′-ethylidenebis (4,6- Di-tert-butylphenol) fluorophosphite, phenyldiisodecylphosphite, tris (2-ethylhexyl) phosphite, tris (isodecyl) phosphite, tris (tridecyl) phosphite, tetrakis (2,4-di-tert-butylphenyl) ) -4,4'-Biphenylene difurf Sphonite, 4,4'-isopropylidenediphenyltetraalkyl (C12-C15) diphosphite, 4,4'-butylidenebis (3-methyl-6-tert-butylphenyl) -ditridecylphosphite, bis (nonylphenyl) Pentaerythritol diphosphite, bis (2,4-di-t-butylphenyl) pentaerythritol-diphosphite, cyclic neopentanetetraylbis (2,6-di-tert-butyl-4-methylphenyl- Phosphite), 1,1,3-tris (2-methyl-4-ditridecylphosphite-5-tert-butylphenyl) butane, tetrakis (2,4-di-tert-butyl-5-methylphenyl)- 4,4'-biphenylenediphosphonite, tri-2-e Tylhexyl phosphite, triisodecyl phosphite, tristearyl phosphite, phenyl diisodecyl phosphite, trilauryl trithiophosphite, distearyl pentaerythritol diphosphite, tris (nonylate phenyl) phosphite tris [2-[[2 , 4,8,10-Tetra-tert-butyldibenzo [d, f] [1,3,2] dioxaphosphin-6-yl] oxy] ethyl] amine, bis (2,4-bis (1, 1-dimethylethyl) -6-methylphenyl) ethyl ester phosphorous acid, ADEKA STAB (registered trademark) 329K (manufactured by ADEKA Corporation), ADEKA STAB (registered trademark) PEP36 (manufactured by ADEKA Corporation), ADEKA STAB (registered trademark) PEP-8 (made by ADEKA Corporation), Sa dstab (registered trademark) P-EPQ (manufactured by Clariant), Weston (registered trademark) 618 (manufactured by GE), Weston (registered trademark) 619G (manufactured by GE), Ultranox (registered trademark) 626 (manufactured by GE) , 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butyldibenz [d, f] [1,3,2] Dioxaphosphepin) and the like.

  The sulfur-based antioxidant is an antioxidant having a sulfur atom in a molecule. Examples of the sulfur-based antioxidant include: dialkylthiodipropionate compounds such as dilauryl thiodipropionate, dimyristyl and distearyl; and β-alkylmercaptopropionic acid of polyols such as tetrakis [methylene (3-dodecylthio) propionate] methane Ester compounds and the like.

  When the polymerizable liquid crystal composition contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.1 to 10 parts by mass, more preferably 0.15 to 10 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. The amount is 7 parts by mass, more preferably 0.2 to 5 parts by mass, particularly preferably 0.2 to 1 part by mass. When the content of the polymerization inhibitor is equal to or more than the above lower limit, the polymerization reaction and gelation of the polymerizable liquid crystal compound during storage can be effectively suppressed, and thus the occurrence of alignment defects in the obtained liquid crystal cured film is suppressed. Cheap. When the content of the polymerization inhibitor is not more than the above upper limit, a liquid crystal cured film having a sufficient degree of polymerization as a retardation film can be obtained.

<Leveling agent>
The polymerizable liquid crystal composition of the present invention may contain a leveling agent. The leveling agent has a function of adjusting the fluidity of the polymerizable liquid crystal composition and making the liquid crystal cured film obtained by applying the composition more flat. Examples of the leveling agent include a silicone-based leveling agent, a polyacrylate-based leveling agent, a perfluoroalkyl-based leveling agent, and the like. Specifically, DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all manufactured by Toray Dow Corning KK), KP321, KP323, KP324, KP326, KP340 KP341, X22-161A, KF6001 (all manufactured by Shin-Etsu Chemical Co., Ltd.), TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF-4446, TSF4452, TSF4460 (all, Momentive Performance Materials Japan GK) Fluorinert (registered trademark) FC-72, FC-40, FC-43, FC-3283 Manufactured by Sumitomo 3M Limited), Megafac (registered trademark) R-08, R-30, R-90, F-410, F-411, F-443, F-445, F-445 F-470, F-474, F-479, F-482, F-483 (all manufactured by DIC Corporation), F-top (trade name) EF301, EF303, EF351, EF352 (all manufactured by Mitsubishi Materials Electronic Chemicals, Inc.), Surflon (registered trademark) S-381, S-382, S-383, S-393, SC-101, SC-105, KH -40, SA-100 (all, manufactured by AGC Seimi Chemical Co., Ltd.), trade names E1830, E5844 (manufactured by Daikin Fine Chemical Laboratory Co., Ltd.), BM-1000, BM-1100, BYK-352, BY -353 and BYK-361N (both trade name: BM Chemie Co., Ltd.), and the like. These leveling agents can be used alone or in combination of two or more. Among these, polyacrylate-based leveling agents and perfluoroalkyl-based leveling agents are preferred.

  The content of the leveling agent is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is in the above range, for example, the polymerizable liquid crystal compound can be easily horizontally aligned, and the obtained liquid crystal cured film tends to be smoother. The polymerizable liquid crystal composition may contain two or more leveling agents.

<Photosensitizer>
The polymerizable liquid crystal composition of the present invention may contain a photosensitizer. The photosensitizer can increase the sensitivity of the photopolymerization initiator. Examples of the photosensitizer include xanthones such as xanthone and thioxanthone; anthracenes having a substituent such as anthracene and an alkyl ether; phenothiazine; and rubrene. The photosensitizers can be used alone or in combination of two or more. The content of the photosensitizer is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and still more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the polymerizable liquid crystal compound. Department.

<Additives>
The polymerizable liquid crystal composition of the present invention may include additives such as an adhesion improver, a release agent, a stabilizer, a coloring agent such as a bluing agent, a flame retardant, and a lubricant. The content of the additive is preferably from 0.01 to 10% by mass, more preferably from 0.1 to 5% by mass, based on the mass of the solid content of the polymerizable liquid crystal composition.

  The polymerizable liquid crystal composition of the present invention includes the polymerizable liquid crystal compound, the polymerization initiator, the organic solvent, and, if necessary, the polymerization inhibitor, the leveling agent, the photosensitizer, and the additive. It can be prepared by mixing by a known method such as stirring.

[Liquid crystal cured film and retardation film]
The present invention includes a liquid crystal cured film obtained by curing the polymerizable liquid crystal composition and a retardation film including the liquid crystal cured film. The liquid crystal cured film is a cured film in which a polymerizable liquid crystal compound is polymerized in an aligned state. Since the cured liquid crystal film and the retardation film of the present invention are formed from the polymerizable liquid crystal composition, they exhibit excellent orientation and can have a uniform film thickness. For this reason, there is no variation in the phase difference and excellent optical characteristics are obtained.

  The cured liquid crystal film of the present invention is preferably a film having anisotropic three-dimensional refractive index. The three-dimensional refractive index ellipsoid formed by the cured liquid crystal film may have biaxial properties, but preferably has uniaxial properties. The liquid crystal cured film may be a horizontally aligned liquid crystal cured film obtained by polymerizing a polymerizable liquid crystal compound in a state of being horizontally oriented with respect to the plane of the liquid crystal cured film, or may be perpendicular to the plane of the liquid crystal cured film. A vertically aligned liquid crystal cured film obtained by polymerizing a polymerizable liquid crystal compound oriented in the direction (thickness direction of the liquid crystal cured film) may be used, or a hybrid alignment liquid crystal cured film or an inclined liquid crystal cured film may be used. .

  In a preferred embodiment of the present invention, the liquid crystal cured film of the present invention is a liquid crystal cured film obtained by curing the polymerizable liquid crystal composition, and is a polymerized liquid crystal aligned in a horizontal direction with respect to a plane of the liquid crystal cured film. This is a horizontal alignment liquid crystal cured film in which a hydrophilic liquid crystal compound is polymerized.

In the horizontal alignment liquid crystal cured film, R (λ), which is an in-plane retardation with respect to light having a wavelength of λ nm, preferably satisfies the optical characteristics represented by the following formula (2). It is more preferable to satisfy the optical characteristics represented by 4) and the following formula (5).
100 nm ≦ Re (550) ≦ 160 nm (2)
[Wherein, Re (550) represents an in-plane retardation value (in-plane retardation) for light having a wavelength of 550 nm. ]
Re (450) / Re (550) ≦ 1.0 (3)
1.00 ≦ Re (650) / Re (550) (4)
[Wherein, Re (450) represents an in-plane retardation value for light having a wavelength of 450 nm, Re (550) represents an in-plane retardation value for light having a wavelength of 550 nm, and Re (650) represents an in-plane retardation value for light having a wavelength of 650 nm. Represents the phase difference value. ]
When “Re (450) / Re (550)” of the liquid crystal cured film exceeds 1.0, light leakage on the short wavelength side in the elliptically polarizing plate including the liquid crystal cured layer tends to increase. It is more preferably 0.95 or less, still more preferably 0.92 or less.

The in-plane retardation value of the liquid crystal cured layer can be adjusted by the thickness of the liquid crystal cured layer. Since the in-plane retardation value is determined by the following equation (5), Δn (λ) and the film thickness d may be adjusted to obtain a desired in-plane retardation value (Re (λ)). . The thickness of the cured liquid crystal layer is preferably 0.5 to 5 μm, more preferably 1 to 3 μm. The thickness of the horizontal alignment liquid crystal cured layer can be measured with an interference thickness gauge, a laser microscope, or a stylus type thickness gauge. Note that Δn (λ) depends on the molecular structure of a polymerizable liquid crystal compound described later.
Re (λ) = d × Δn (λ) (5)
(In the formula, Re (λ) represents an in-plane retardation value at a wavelength λnm, d represents a film thickness, and Δn (λ) represents a birefringence at a wavelength λnm.)

  The polymerization rate of the liquid crystal cured film is preferably 70% or more, more preferably 75% or more, and further preferably 80% or more. When the degree of polymerization of the liquid crystal cured film is equal to or more than the above value, the liquid crystal can have a sufficient degree of curing that can be used for retardation films. The polymerization rate can be measured by the method described in the examples.

The cured liquid crystal film of the present invention is preferably formed on a substrate or an alignment film. The retardation film of the present invention may include the cured liquid crystal film, may further include a substrate or an alignment film, and preferably further includes a substrate and an alignment film. Such a retardation film includes the following steps;
A step of applying the polymerizable liquid crystal composition on a substrate or an alignment film to obtain a coating layer (hereinafter, also referred to as a “coating step”);
Removing the solvent from the obtained coating layer to orient the polymerizable liquid crystal compound (hereinafter, also referred to as “drying step”); and curing the polymerizable liquid crystal layer by polymerizing the aligned polymerizable liquid crystal compound. To obtain a cured liquid crystal film (hereinafter also referred to as “curing step”)
Can be produced. When the polymerizable liquid crystal composition is formed on an alignment film, the alignment film is preferably formed on a substrate.

  In the coating step, the polymerizable liquid crystal composition may be coated on a substrate or an alignment film by, for example, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a CAP coating method, a slit coating method, a die coating method. And the like. Further, a coating method using a coater such as a dip coater, a bar coater, and a spin coater may be used. Among these, a CAP coating method, an ink-jet method, a dip coating method, a slit coating method, a die coating method, and a coating method using a bar coater are preferable because they can be continuously applied in a roll-to-roll format. In the case of coating in a roll-to-roll format, a composition for forming an alignment film or the like may be coated on a substrate to form an alignment film, and the polymerizable liquid crystal composition may be continuously coated on the obtained alignment film. it can.

Examples of the substrate include a glass substrate and a film substrate, and a film substrate is preferable from the viewpoint of processability, and a long roll-shaped film is more preferable in that it can be continuously manufactured. Examples of the resin constituting the film substrate include polyolefins such as polyethylene, polypropylene and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid esters; And cellulose esters such as cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; and resins such as polyphenylene sulfide and polyphenylene oxide.
Examples of commercially available cellulose ester base materials include "Fujitac Film" (manufactured by Fuji Photo Film Co., Ltd.); "KC8UX2M", "KC8UY" and "KC4UY" (all manufactured by Konica Minolta Opto Co., Ltd.).
Commercially available cyclic olefin resins include “Topas” (registered trademark) (manufactured by Ticona (Germany)), “ARTON” (registered trademark) (manufactured by JSR Corporation), “ZEONOR” (registered trademark), "ZEONEX" (registered trademark) (both manufactured by Nippon Zeon Co., Ltd.) and "Apel" (registered trademark) (manufactured by Mitsui Chemicals, Inc.). Such a cyclic olefin-based resin can be used as a substrate by forming a film by a known method such as a solvent casting method or a melt extrusion method. A commercially available cyclic olefin-based resin substrate can also be used. Commercially available cyclic olefin-based resin substrates include “ESCINA” (registered trademark), “SCA40” (registered trademark) (all manufactured by Sekisui Chemical Co., Ltd.), and “ZEONOR FILM” (registered trademark) (Nippon Zeon Co., Ltd.) And "ARTON FILM" (registered trademark) (manufactured by JSR Corporation).
The thickness of the substrate is preferably thin in terms of a mass that can be handled practically. However, if the thickness is too small, the strength tends to decrease and the workability tends to be poor. The thickness of the substrate is usually from 5 to 300 μm, preferably from 20 to 200 μm. Further, by transferring the cured liquid crystal film alone or a laminate of the cured liquid crystal film and the alignment film after removing the base material, a further thinning effect can be obtained.

  The alignment film has an alignment regulating force for aligning the polymerizable liquid crystal compound in a desired direction. The alignment film preferably has a solvent resistance that does not dissolve by application of the polymerizable liquid crystal composition or the like, and also has heat resistance in heat treatment for removing the solvent or aligning the polymerizable liquid crystal compound described below. Examples of the alignment film include a rubbing alignment film, a photo alignment film, a grub alignment film having an uneven pattern and a plurality of grooves on the surface, and a stretched film. When applied to a long roll-shaped film, a photo-alignment film is preferred in that the alignment direction can be easily controlled.

  Such an alignment film facilitates the alignment of the polymerizable liquid crystal compound. Further, various alignments such as vertical alignment, horizontal alignment, hybrid alignment, and tilt alignment can be controlled depending on the type of alignment film, rubbing conditions, and light irradiation conditions.

  The thickness of the alignment film is usually 10 to 10000 nm, preferably 10 to 1000 nm, and more preferably 50 to 300 nm.

  Examples of the orientation polymer used in the rubbing alignment film include, for example, polyamide or gelatin having an amide bond, polyimide having an imide bond and polyamic acid which is a hydrolyzate thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, or polyacrylamide. Oxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylates. The oriented polymers can be used alone or in combination of two or more.

  The rubbing alignment film is usually formed by applying a composition in which an alignment polymer is dissolved in a solvent (hereinafter, also referred to as an alignment polymer composition) to a substrate, removing the solvent to form a coating film, and forming the coating film. Rubbing can provide an alignment regulating force.

  The concentration of the oriented polymer in the oriented polymer composition may be within a range in which the oriented polymer is completely dissolved in the solvent. The content of the oriented polymer with respect to the oriented polymer composition is preferably 0.1 to 20% by mass, and more preferably 0.1 to 10% by mass.

  Oriented polymer compositions are commercially available. Examples of commercially available oriented polymer compositions include Sanever (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) and Optmer (registered trademark, manufactured by JSR Corporation).

  Examples of the method for applying the alignment polymer composition to the substrate include the same method as the method for applying the polymerizable liquid crystal composition to the substrate or the alignment film. Examples of a method for removing the solvent contained in the oriented polymer composition include a natural drying method, a ventilation drying method, a heating drying method, and a reduced-pressure drying method.

  As a method of the rubbing treatment, for example, a method of bringing the coating film into contact with a rotating rubbing roll around which a rubbing cloth is wound. By performing masking when performing the rubbing treatment, a plurality of regions (patterns) having different orientation directions can be formed in the orientation film.

  The photo-alignment film is usually made of a polymer, oligomer or monomer having a photoreactive group. When a liquid crystal cured film is continuously formed, a polymer having a molecular weight of 5,000 or more is preferable from the viewpoint of solvent resistance and the like. When the polymerizable liquid crystal compound has a (meth) acryloyl group from the viewpoint of affinity, an acrylic polymer is used. Preferably, there is. The photo-alignment film is obtained by applying a composition containing a polymer, oligomer or monomer having a photoreactive group and a solvent (hereinafter, also referred to as “photo-alignment film forming composition”) to a substrate, and drying and removing the solvent. It is obtained by irradiating polarized light (preferably, polarized UV). The photo-alignment film is more preferable in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

  The photoreactive group refers to a group that generates alignment ability upon irradiation with light. Specific examples include groups involved in a photoreaction that is a source of alignment ability such as an orientation-induced reaction, isomerization reaction, photodimerization reaction, photocrosslinking reaction, or photodecomposition reaction of molecules generated by light irradiation. As the photoreactive group, a group having an unsaturated bond, particularly a double bond is preferable, and a carbon-carbon double bond (C = C bond), a carbon-nitrogen double bond (C = N bond), and a nitrogen-nitrogen A group having at least one selected from the group consisting of a double bond (N = N bond) and a carbon-oxygen double bond (C = O bond) is particularly preferable.

  Examples of the photoreactive group having a C ＝ C bond include a vinyl group, a polyene group, a stilbene group, a stilbazole group, a stilbazolium group, a chalcone group, and a cinnamoyl group. Examples of the photoreactive group having a C = N bond include groups having a structure such as an aromatic Schiff base and an aromatic hydrazone. Examples of the photoreactive group having an N = N bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and a group having an azoxybenzene structure. Examples of the photoreactive group having a C ＝ O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have a substituent such as an alkyl group, an alkoxy group, an aryl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group, and a halogenated alkyl group.

  A group involved in a photodimerization reaction or a photocrosslinking reaction is preferable because of excellent orientation. Above all, a photoreactive group involved in the photodimerization reaction is preferable, and a cinnamoyl group is preferable in that a relatively small amount of polarized light required for alignment is obtained, and a photoalignment film excellent in thermal stability and stability over time is easily obtained. And chalcone groups are preferred. As the polymer having a photoreactive group, a polymer having a cinnamoyl group such that the terminal portion of the polymer side chain has a cinnamic acid structure or a cinnamic acid ester structure is particularly preferable.

  The content of the polymer or monomer having a photoreactive group in the composition for forming a photo-alignment film can be adjusted depending on the type of the polymer or monomer and the thickness of the desired photo-alignment film. And more preferably in the range of 0.3 to 10% by mass.

  As a method of applying the composition for forming a photo-alignment film to a substrate, the same method as the method of applying the polymerizable liquid crystal composition to the substrate or the alignment film can be used. The method for removing the solvent from the applied composition for forming a photo-alignment film includes the same method as the method for removing the solvent from the oriented polymer composition.

  In order to irradiate polarized light, even if the solvent is removed from the composition for forming a photo-alignment film applied on the substrate, the polarized light is directly radiated from the substrate side. Irradiation may be performed by transmitting the light through a material. Preferably, the polarized light is substantially parallel light. The wavelength of the polarized light to be applied is preferably in a wavelength range in which the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet) having a wavelength in the range of 250 nm to 400 nm is particularly preferable. Examples of the light source that emits the polarized light include a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, and an ultraviolet laser such as KrF and ArF. Among them, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp are preferable because of high emission intensity of ultraviolet light having a wavelength of 313 nm. By irradiating light from the light source through an appropriate polarizing element, polarized UV can be applied. Examples of the polarizing element include a polarizing filter, a polarizing prism such as Glan-Thompson and Glan-Taylor, and a wire grid. Among them, a wire grid type polarizing element is preferable from the viewpoint of increasing the area and resistance to heat. Note that a plurality of regions (patterns) having different directions of liquid crystal alignment can be formed by performing masking when performing rubbing or polarized light irradiation.

The groove alignment film is a film having an uneven pattern or a plurality of grooves (grooves) on the film surface. When a polymerizable liquid crystal compound is applied to a film having a plurality of linear grubs arranged at equal intervals, liquid crystal molecules are aligned in a direction along the groove.
The method for obtaining the grub alignment film includes a method of forming an uneven pattern by performing exposure and development and rinsing treatment after exposure through an exposure mask having a pattern-shaped slit on the photosensitive polyimide film surface, a plate having grooves on the surface. A method of forming a layer of a UV-curable resin before curing on a shape-like master, transferring the resin layer to a substrate, and then curing, and forming a plurality of layers of the UV-curable resin before curing formed on the substrate, There is a method in which a roll-shaped master having grooves is pressed against the surface to form irregularities and then cured.

  In the drying step, examples of the method for removing the solvent from the coating layer obtained in the coating step include natural drying, ventilation drying, heat drying, drying under reduced pressure, and a method combining these. Above all, natural drying or heat drying is preferable. The drying temperature is preferably in the range of 0 to 200 ° C, more preferably in the range of 20 to 150 ° C, and still more preferably in the range of 50 to 130 ° C. The drying time is preferably from 10 seconds to 20 minutes, more preferably from 30 seconds to 10 minutes.

  In the curing step, the polymerization of the polymerizable liquid crystal compound aligned in the drying step can be performed by a known method for polymerizing a compound having a polymerizable group. For example, photopolymerization by irradiation with active energy rays is employed. be able to.

  The active energy ray to be irradiated is appropriately selected depending on the type of the polymerizable liquid crystal compound (particularly, the type of the photopolymerizable functional group of the polymerizable liquid crystal compound), the type of the photopolymerization initiator, and the amount thereof. . Specifically, it includes at least one kind of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-ray, α-ray, β-ray, and γ-ray. Above all, ultraviolet light is preferable in that it is easy to control the progress of the polymerization reaction and that a photopolymerization device that is widely used in this field can be used, and the photopolymerization can be performed by ultraviolet light. It is preferable to select the type of the liquid crystal compound.

  Examples of the light source of the active energy ray include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, LED light sources emitting 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, and the like.

The ultraviolet irradiation intensity is usually 10 to 3,000 mW / cm ² . The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating the photopolymerization initiator. The time for irradiating light is usually 0.1 second to 10 minutes, preferably 0.1 second to 5 minutes, more preferably 0.1 second to 3 minutes, and further preferably 0.1 second. ~ 1 minute. When irradiation is performed once or plural times with such ultraviolet irradiation intensity, the integrated light amount is 10 to 3,000 mJ / cm ² , preferably 50 to 2,000 mJ / cm ² , more preferably 100 to 1,000 mJ / cm ² . ² . When the integrated light amount is within this range, the obtained liquid crystal cured film tends to be sufficiently cured, and the liquid crystal cured film can be prevented from being colored.

  The thickness of the cured liquid crystal film of the present invention is preferably 0.5 to 5 μm, more preferably 1 to 3 μm from the viewpoint of thinning. In addition, the film thickness of the liquid crystal cured film and the retardation film can be measured by an interference film thickness meter, a laser microscope, or a stylus type film thickness meter.

[Elliptical polarizing plate and display device]
The elliptically polarizing plate of the present invention includes the retardation film and a polarizing film. The elliptically polarizing plate can be obtained by laminating the retardation film and the polarizing film via an adhesive.
In one embodiment of the present invention, when the retardation film is laminated on the polarizing film, the retardation film is laminated so that the slow axis (optical axis) of the retardation film and the absorption axis of the polarizing film become substantially 45 °. Is preferred. The function as an elliptically polarizing plate can be obtained by laminating the retardation film so that the slow axis (optical axis) and the absorption axis of the polarizing film are substantially at 45 °. In addition, substantially 45 ° is usually in the range of 45 ± 5 °.

  The polarizing film is made of a polarizer having a polarizing function. Examples of the polarizer include a stretched film in which a dye having absorption anisotropy is adsorbed, and a film in which a dye having absorption anisotropy is applied and oriented. Examples of the dye having absorption anisotropy include dichroic dyes.

  Stretched film adsorbing the dye having absorption anisotropy is usually a step of uniaxially stretching the polyvinyl alcohol-based resin film, by dyeing the polyvinyl alcohol-based resin film with the dichroic dye, It is manufactured through a step of adsorbing, a step of treating the polyvinyl alcohol-based resin film to which the dichroic dye is adsorbed with a boric acid aqueous solution, and a step of washing with water after the treatment with the boric acid aqueous solution. A polarizing film is obtained by laminating the thus obtained polarizer and the transparent protective film. Examples of the dichroic dye include iodine and a dichroic organic dye. Examples of the dichroic organic dye include a dichroic direct dye composed of a disazo compound such as C.I. DIRECT RED 39 and a dichroic direct dye composed of a compound such as trisazo and tetrakisazo. As described above, the thickness of the polarizer obtained by subjecting the polyvinyl alcohol-based resin film to uniaxial stretching, dyeing with a dichroic dye, boric acid treatment, washing with water and drying is preferably 5 to 40 μm.

  As a film on which a dye having absorption anisotropy is applied and oriented, a film obtained by applying a composition containing a dichroic dye having liquid crystallinity, or a composition containing a dichroic dye and a polymerizable liquid crystal compound And a film obtained by applying an object. It is preferable that a film coated with a dye having absorption anisotropy is thin, but if it is too thin, strength tends to decrease and processability tends to be poor. The thickness of the film is usually 20 μm or less, preferably 5 μm or less, more preferably 0.5 to 3 μm. A film obtained by applying a composition containing a dichroic dye and a polymerizable liquid crystal compound from the point of being obtained as a hard film and forming a polymer in a state where the polymerizable liquid crystal compound is oriented is preferable, and in that high polarization performance is obtained. A film in which the polymerizable liquid crystal compound has a smectic liquid crystal phase and a polymer is formed in the smectic liquid crystal phase state is more preferable. Specific examples of such a polarizer include Japanese Patent No. 4719156, Japanese Patent No. 4937252, Japanese Patent No. 5777663, Japanese Patent No. 5923941, Japanese Patent No. 5982762, Japanese Patent No. 60064885, Japanese Patent No. 6036452, and Japanese Patent No. 6036452. And the polarizers described in Japanese Patent No. 6098053 and Japanese Patent No. 61332049.

  The elliptically polarizing plate of the present invention may include a layer other than the retardation film, the polarizing film, and the adhesive (adhesive layer). Other layers include, for example, an isotropic protective film, a hard coat layer, and the like.

  The present invention includes a display device including the elliptically polarizing plate. The display device can be obtained by laminating an elliptically polarizing plate, preferably a retardation film of the elliptically polarizing plate, to the display device via an adhesive. A display device is a device having a display mechanism and includes a light-emitting element or a light-emitting device as a light-emitting source. Examples of the display device include a liquid crystal display device, an organic electroluminescence (EL) display device, an inorganic electroluminescence (EL) display device, a touch panel display device, an electron emission display device (eg, a field emission display device (eg, FED), and a surface field emission display device). (SED)), electronic paper (display using electronic ink or electrophoretic element), plasma display, projection display (grating light valve (GLV) display, display having digital micromirror device (DMD)) Etc.) and piezoelectric ceramic displays. The liquid crystal display device includes any of a transmission type liquid crystal display device, a transflective type liquid crystal display device, a reflection type liquid crystal display device, a direct-view type liquid crystal display device, and a projection type liquid crystal display device. These display devices may be display devices that display a two-dimensional image or stereoscopic display devices that display a three-dimensional image. Particularly, as the display device including the elliptically polarizing plate of the present invention, an organic EL display device and a touch panel display device are preferable.

  As an adhesive for bonding the polarizing film and the retardation film in forming the elliptically polarizing plate, or as an adhesive for bonding the elliptically polarizing plate and the display in forming the display device, Examples include a pressure-sensitive adhesive, a dry-solidified adhesive, and a chemically reactive adhesive. Examples of the chemically reactive adhesive include an active energy ray-curable adhesive. As the adhesive in the formation of the elliptically polarizing plate, an adhesive layer formed from a pressure-sensitive adhesive, a dry-setting adhesive, an active energy ray-curable adhesive is preferable, and the adhesive in the formation of a display device is preferred. As the pressure-sensitive adhesive, an active energy ray-curable adhesive is preferable.

The pressure-sensitive adhesive usually contains a polymer and may contain a solvent.
Examples of the polymer include an acrylic polymer, a silicone polymer, polyester, polyurethane, and polyether. Among them, acrylic pressure-sensitive adhesives containing acrylic polymers have excellent optical transparency, moderate wettability and cohesive strength, excellent adhesion, and high weather resistance and heat resistance. Floating or peeling hardly occurs under the condition of humidification or humidification, which is preferable.

  As the acrylic polymer, a (meth) acrylate in which the alkyl group in the ester portion is an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, or a butyl group (hereinafter, acrylate and methacrylate are collectively referred to as (meth) acrylate) (Acrylic acid and methacrylic acid may be collectively referred to as (meth) acrylic acid.) And (meth) having a functional group such as (meth) acrylic acid or hydroxyethyl (meth) acrylate. Copolymers with acrylic monomers are preferred.

  The pressure-sensitive adhesive containing such a copolymer is excellent in tackiness, and can be removed relatively easily without causing adhesive residue on the display device even when it is removed after pasting to the display device. Is preferred because it is possible. The glass transition temperature of the acrylic polymer is preferably 25 ° C. or lower, more preferably 0 ° C. or lower. The weight average molecular weight of such an acrylic polymer is preferably 100,000 or more.

Examples of the solvent include the solvents mentioned above as the organic solvent. The pressure-sensitive adhesive may contain a light diffusing agent. The light diffusing agent is an additive that imparts light diffusing property to the pressure-sensitive adhesive, and may be fine particles having a refractive index different from that of the polymer contained in the pressure-sensitive adhesive. Examples of the light diffusing agent include fine particles made of an inorganic compound and fine particles made of an organic compound (polymer). Most of the polymers contained in the pressure-sensitive adhesive as an active ingredient, including acrylic polymers, have a refractive index of about 1.4 to 1.6, so that the light diffusing agent having a refractive index of 1.2 to 1.8 It is preferable to select an appropriate one. The difference in the refractive index between the polymer contained in the pressure-sensitive adhesive as an active ingredient and the light diffusing agent is usually 0.01 or more, and is preferably 0.01 to 0.2 from the viewpoint of the brightness and display properties of the display device. The fine particles used as the light diffusing agent are preferably spherical fine particles, which are also nearly monodisperse, and more preferably fine particles having an average particle diameter of 2 to 6 μm. The refractive index is measured by a general minimum declination method or an Abbe refractometer.
Examples of the fine particles made of an inorganic compound include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45). Examples of the fine particles composed of an organic compound (polymer) include melamine beads (refractive index: 1.57), polymethyl methacrylate beads (refractive index: 1.49), and methyl methacrylate / styrene copolymer resin beads (refractive index: 1.50). ~ 1.59), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1.46), and silicone Resin beads (refractive index: 1.46); The content of the light diffusing agent is usually 3 to 30 parts by mass based on 100 parts by mass of the polymer.
The thickness of the pressure-sensitive adhesive is not particularly limited because it is determined according to the adhesive strength and the like, but is usually 1 to 40 μm. In light of workability and durability, the thickness is preferably 3 to 25 μm, and more preferably 5 to 20 μm. By setting the thickness of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive to 5 to 20 μm, the brightness of the display device when viewed from the front or obliquely is maintained, and the blur or blur of the display image is reduced. It can be less likely to occur.

The dry-setting adhesive may contain a solvent.
The dry-solidifying adhesive includes a polymer of a monomer having a protic functional group such as a hydroxyl group, a carboxyl group or an amino group and an ethylenically unsaturated group, or a urethane resin as a main component. Examples of the composition include a composition containing a crosslinking agent or a curable compound such as an aldehyde, an epoxy compound, an epoxy resin, a melamine compound, a zirconia compound, and a zinc compound. Examples of the polymer of a monomer having a protic functional group such as a hydroxyl group, a carboxyl group, or an amino group and an ethylenically unsaturated group include ethylene-maleic acid copolymer, itaconic acid copolymer, acrylic acid copolymer, and acrylamide. Copolymers, saponified polyvinyl acetate, polyvinyl alcohol-based resins, and the like.

  Examples of the polyvinyl alcohol resin include polyvinyl alcohol, partially saponified polyvinyl alcohol, completely saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. No. The content of the polyvinyl alcohol-based resin in the aqueous adhesive is usually 1 to 10 parts by mass, preferably 1 to 5 parts by mass with respect to 100 parts by mass of water.

  Examples of the urethane resin include a polyester ionomer type urethane resin. The polyester-based ionomer type urethane resin referred to herein is a urethane resin having a polyester skeleton and a resin into which a small amount of an ionic component (hydrophilic component) is introduced. Such an ionomer type urethane resin is emulsified in water to form an emulsion without using an emulsifier, and thus can be used as an aqueous adhesive. When a polyester ionomer type urethane resin is used, it is effective to mix a water-soluble epoxy compound as a crosslinking agent.

  Examples of the epoxy resin include a polyamide epoxy resin obtained by reacting epichlorohydrin with a polyamide polyamine obtained by reacting a polyalkylene polyamine such as diethylene triamine or triethylene tetramine with a dicarboxylic acid such as adipic acid. As commercially available products of such polyamide epoxy resins, “SUMIREZ Resin (registered trademark) 650” and “SUMIREZ Resin 675” (all manufactured by Sumika Chemtex Co., Ltd.), “WS-525” (manufactured by Nippon PMC Co., Ltd.) And the like. When the epoxy resin is blended, its addition amount is usually 1 to 100 parts by mass, preferably 1 to 50 parts by mass with respect to 100 parts by mass of the polyvinyl alcohol-based resin.

  The thickness of the adhesive layer formed from the dried and solidified adhesive is generally 0.001 to 5 μm, preferably 0.01 to 2 μm, and more preferably 0.01 to 0.5 μm. is there. If the pressure-sensitive adhesive layer formed from the dried and solidified adhesive is too thick, the optically anisotropic layer tends to have poor appearance.

The active energy ray-curable adhesive may contain a solvent. The active energy ray-curable adhesive is an adhesive that cures when irradiated with an active energy ray.
Examples of the active energy ray-curable adhesive include a cationically polymerizable adhesive containing an epoxy compound and a cationic polymerization initiator, a radically polymerizable adhesive containing an acrylic curing component and a radical polymerization initiator, and an epoxy compound. An adhesive containing both a cationically polymerizable curing component such as a cationic polymerizable curing component and a radically polymerizable curing component such as an acrylic compound, and further containing a cationic polymerization initiator and a radical polymerization initiator, and including these polymerization initiators And an adhesive that is cured by irradiating an electron beam.

Among them, a radical polymerizable active energy ray-curable adhesive containing an acrylic curing component and a radical polymerization initiator, and a cationic polymerizable active energy ray-curable adhesive containing an epoxy compound and a cationic polymerization initiator are used. preferable. Examples of the acrylic curing component include (meth) acrylates such as methyl (meth) acrylate and hydroxyethyl (meth) acrylate, and (meth) acrylic acid. The active energy ray-curable adhesive containing an epoxy compound may further contain a compound other than the epoxy compound. Examples of compounds other than epoxy compounds include oxetane compounds and acrylic compounds.
Examples of the radical polymerization initiator include the photopolymerization initiators described above. Commercially available cationic polymerization initiators include “Kayarad” (registered trademark) series (manufactured by Nippon Kayaku Co., Ltd.), “Cyracure UVI” series (manufactured by Dow Chemical Company), “CPI” series (manufactured by San Apro Corporation), "TAZ", "BBI" and "DTS" (all manufactured by Midori Kagaku Co., Ltd.), "ADEKA OPTOMER" series (manufactured by ADEKA), "RHODORSIL" (registered trademark) (manufactured by Rhodia Co., Ltd.) and the like. Can be The content of the radical polymerization initiator and the cationic polymerization initiator is usually 0.5 to 20 parts by mass, preferably 1 to 15 parts by mass, based on 100 parts by mass of the active energy ray-curable adhesive.

  The active energy ray-curable adhesive further contains an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, a defoaming agent, and the like. You may.

  In the present specification, an active energy ray is defined as an energy ray that can decompose a compound that generates an active species to generate an active species. Examples of such active energy rays include visible light, ultraviolet rays, infrared rays, X-rays, α-rays, β-rays, γ-rays, and electron beams, and ultraviolet rays and electron beams are preferred. Preferred irradiation conditions of the ultraviolet ray are the same as those for the polymerization of the polymerizable liquid crystal compound described above.

Hereinafter, the present invention will be described in more detail with reference to examples. "%" And "parts" in the examples are% by mass and parts by mass unless otherwise specified.
The devices, measurement methods, and evaluation methods used in the examples are as follows.

[Measurement of film thickness]
The film thicknesses of the substrate, the photo-alignment film and the cured liquid crystal film in the examples and comparative examples were measured using an ellipsometer M-220 manufactured by JASCO Corporation.

[Measurement of viscosity]
In the Examples and Comparative Examples, the viscosity V and the viscosity of the solvent used 48 hours after the completion of mixing all the components contained in the polymerizable liquid crystal composition were measured using a vibration type viscometer VM-10A manufactured by CBC Materials Co., Ltd. Using -L, it was measured in accordance with "JIS 8803Z: 2011 Method for measuring viscosity of liquid".

[Measurement of maximum absorption wavelength λ _max (LC)]
The maximum absorption wavelengths of the polymerizable liquid crystal compounds (A) and (B), the photopolymerization initiator, and the cured liquid crystal film are in a UV-visible spectrophotometer (“UV-2450” manufactured by Shimadzu Corporation) in chloroform. It measured using.

[Measurement of polymerization rate]
The liquid crystal cured films obtained in Examples and Comparative Examples were measured for infrared total reflection absorption spectrum (“Model 670-IR” manufactured by Agilent) (incident angle: 45 °), and the obtained measurement results ( Values of peak intensity I (1) derived from in-plane bending vibration (1408 cm ⁻¹ ) of ethylenic unsaturated bond and peak intensity I (2) derived from stretching vibration (1504 cm ⁻¹ ) of unsaturated bond of aromatic ring. ), P ′ (P value on the surface irradiated with ultraviolet rays among the surfaces perpendicular to the thickness direction of the liquid crystal cured film) was calculated.
Further, a solution obtained by dissolving the polymerizable liquid crystal compound (A) in chloroform was dropped on germanium crystals and dried to obtain a thin layer of the polymerizable liquid crystal compound (A). An infrared total reflection absorption spectrum was measured for the obtained thin layer, and P0 (P value of the polymerizable liquid crystal compound (A)) was calculated from the obtained measurement results.
From the values of P ′ and P0, a polymerization rate defined by (1−P ′ / P0) × 100 was calculated. The larger the value, the higher the degree of curing of the liquid crystal cured film.

[Evaluation of orientation]
The cured liquid crystal films obtained in Examples and Comparative Examples were observed at a magnification of 400 times using a polarizing microscope (BX51, manufactured by Olympus Corporation). A sample with good orientation was rated as "O", and a sample with poor orientation, such as poor orientation on the surface, was rated as "x".

[Evaluation of film thickness unevenness]
A pair of linear polarizers was overlaid on a light table so as to form a cross Nicol. The liquid crystal cured films obtained in Examples and Comparative Examples were placed between linear polarizers placed on a light table as described above. At this time, the slow axis of the liquid crystal cured film was set to be substantially 45 ° with respect to the absorption axis of the polarizer when viewed from the thickness direction. Then, it observed visually. According to the uniformity of the observed image (uniformity of the phase difference), the surface was almost uniform and no unevenness was observed.

[Example 1]
<Preparation of composition for forming photo-alignment film>
5 parts of a photo-alignment material having the following structure and 95 parts of cyclopentanone (solvent) were mixed as components, and the resulting mixture was stirred at 80 ° C. for 1 hour to obtain a composition for forming a photo-alignment film (1). I got
Photo-alignment material:

<Preparation of polymerizable liquid crystal composition>
Polymerizable liquid crystal compound (A) having the following structure, dibutylhydroxytoluene (polymerization inhibitor) (BHT; manufactured by Wako Pure Chemical Industries), polyacrylate compound (leveling agent) (BYK-361N; manufactured by BYK-Chemie), photopolymerization described below The initiator was mixed according to the composition shown in Table 1. Next, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration of the polymerizable liquid crystal composition became 9%, and the mixture was stirred at 80 ° C. for 1 hour, thereby obtaining the polymerizable liquid crystal composition (1). I got
After the completion of the stirring, that is, after the completion of mixing of all the components contained in the polymerizable liquid crystal composition, the polymerizable liquid crystal composition (1) was stored in a closed container under a fluorescent lamp (40 W) at 23 ° C. for 48 hours. The viscosity V at 23 ° C. of the polymerizable liquid crystal composition 48 hours after the completion of the mixing was 2.53 mPa · s. The viscosity of NMP at 23 ° C. was 1.89 mPa · s.

Polymerizable liquid crystal compound (A):

The polymerizable liquid crystal compound (A) was synthesized by the method described in JP-A-2010-31223. The maximum absorption wavelength λ _max (LC) of the polymerizable liquid crystal compound (A) measured in chloroform was 350 nm.

  The content of dibutylhydroxytoluene (polymerization inhibitor) in the polymerizable liquid crystal composition was 0.3 part with respect to 100 parts of the polymerizable liquid crystal compound (A).

  The content of the polyacrylate compound (leveling agent) in the polymerizable liquid crystal composition was 0.01 part with respect to 100 parts by mass of the polymerizable liquid crystal compound (A).

The following two types were used as photopolymerization initiators, and the following photopolymerization initiators were added to 100 parts of the polymerizable liquid crystal compound (A) in the following amounts.
-Oxime ester type carbazole compound (Irgacure OXE-03 (manufactured by BASF Japan)): 7.5 parts with respect to 100 parts of the polymerizable liquid crystal compound (A). The maximum absorption wavelength of the initiator measured in chloroform is 305 nm and 350 nm.
-2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one (Irgacure 369 (Irg369); manufactured by BASF Japan Ltd.): 3 per 100 parts of the polymerizable liquid crystal compound (A). Department. The maximum absorption wavelength of the initiator measured in chloroform is 320 nm.

<Production of liquid crystal cured film and retardation film>
A cycloolefin polymer (COP) film (ZeonorFilm (registered trademark) “ZF-14”, manufactured by Zeon Corporation, film thickness 23 μm, manufactured by Zeon Corporation) as a base material is supplied to a corona treatment apparatus (Kasuga Electric Co., Ltd.) AGF-B10 "). Next, the above-described composition (1) for forming a photo-alignment film is applied to the surface of a COP film (substrate) that has been subjected to corona treatment using a bar coater, dried at 80 ° C. for 1 minute, and then irradiated with polarized UV. Polarized UV exposure was performed using an apparatus (“SPOT CURE SP-7 with polarizer unit” manufactured by Ushio Inc.) at an integrated light amount of 100 mJ / cm ² to obtain a photo-alignment film. The thickness of the obtained photo-alignment film was 100 nm. The corona treatment was performed once using the above-described corona treatment device under the conditions of an output of 0.3 kW and a treatment speed of 3 m / min.
Subsequently, using a bar coater, the polymerizable liquid crystal composition (1) 48 hours after the completion of the above-described mixing was applied on the photo-alignment film, dried at 120 ° C. for 1 minute, and then subjected to a high-pressure mercury lamp ( By irradiating ultraviolet rays from the application surface side of the coating solution (in a nitrogen atmosphere, the integrated light amount at a wavelength of 313 nm is 500 mJ / cm ² ) using “Unicure VB-15201BY-A” manufactured by USHIO Inc. A liquid crystal cured film was formed. The thickness of the liquid crystal cured film was 2 μm. Thus, a retardation film including the base material, the photo-alignment film, and the liquid crystal cured film was obtained. The thickness of the retardation film was 25 μm. The maximum absorption wavelength of the obtained cured liquid crystal film was 350 nm.

[Example 2]
A polymerizable liquid crystal composition (2), a cured liquid crystal film, and a retardation film were obtained in the same manner as in Example 1, except that the solid content concentration of the polymerizable liquid crystal composition was 13%.

[Example 3]
A polymerizable liquid crystal composition (3), a liquid crystal cured film, and a retardation film were obtained in the same manner as in Example 1 except that the solid content concentration of the polymerizable liquid crystal composition was set to 15%.

[Example 4]
A polymerizable liquid crystal composition (4), a liquid crystal cured film, and a retardation film were obtained in the same manner as in Example 1, except that the solvent was changed to cyclopentanone. The viscosity of cyclopentanone at 23 ° C. was 1.08 mPa · s.

[Example 5]
Except that the polymerizable liquid crystal compound was LC242 (manufactured by BASF Japan Ltd.), the solvent was propylene glycol monomethyl ether acetate (PGMEA), the solid content concentration was 13%, and the content of dibutylhydroxytoluene was 2%. In the same manner as in Example 1, a polymerizable liquid crystal composition (5), a liquid crystal cured film, and a retardation film were obtained. The viscosity of PGMEA at 23 ° C. was 1.10 mPa · s.

[Example 6]
A polymerizable liquid crystal composition (6), a liquid crystal cured film, and a retardation film were obtained in the same manner as in Example 1 except that the content of dibutylhydroxytoluene was set to 5%.

[Example 7]
A polymerizable liquid crystal composition (7), a liquid crystal cured film, and a retardation film were obtained in the same manner as in Example 1, except that the polymerizable liquid crystal composition was changed to a polymerizable liquid crystal compound (B) having the following structure. . The polymerizable liquid crystal compound (B) was synthesized by the method described in JP-A-2010-24438. The maximum absorption wavelength λ _max (LC) of the polymerizable liquid crystal compound (B) measured in chloroform is 330 nm.

Polymerizable liquid crystal compound (B):

[Comparative Examples 1 to 3]
The polymerizable liquid crystal compositions (8) to (10) and the liquid crystal were prepared in the same manner as in Example 1 except that the solid content and the content of dibutylhydroxytoluene (polymerization inhibitor) were as shown in Table 1. A cured film and a retardation film were obtained. The viscosity at 23 ° C. immediately after the completion of the mixing of the polymerizable liquid crystal composition (8) prepared in Comparative Example 1 was 3.12 mPa.

[Comparative Examples 4 and 5]
The polymerizable liquid crystal compound was LC242 (manufactured by BASF Japan Ltd.), the solvent was propylene glycol monomethyl ether acetate (PGMEA), the solid content was 13%, and the content of dibutylhydroxytoluene (polymerization inhibitor) was as shown in Table 1. Except for following the description, polymerizable liquid crystal compositions (11) and (12) were obtained in the same manner as in Example 1. When the polymerizable liquid crystal compositions (11) and (12) were stored in a closed container under a fluorescent lamp (40 W) at 23 ° C. for 48 hours, gelation proceeded, and the viscosity could not be measured. The liquid crystal cured film and the retardation film could not be formed.

  Solid content concentration c (mass fraction) of the polymerizable liquid crystal compositions obtained in Examples and Comparative Examples, content of polymerization inhibitor (% by mass), and viscosity V (mPa · s) at 48 hours after mixing. , And cV are shown in Table 1. Table 1 shows the evaluations of the orientation and the unevenness of the film thickness of the liquid crystal cured films obtained in the examples and comparative examples, and the polymerization rates.

  As shown in Table 1, the liquid crystal cured films obtained from the polymerizable liquid crystal compositions of Examples 1 to 7 have good evaluation of the orientation and the unevenness of the film thickness. It was found that can prevent the occurrence of alignment defects and unevenness in the thickness of the obtained liquid crystal cured film even after long-term storage. Further, the cured liquid crystal films of Examples 1 to 7 all had a polymerization rate of 72% or more, and were found to have a sufficient degree of curing for use as a retardation film. On the other hand, the cured liquid crystal films obtained from the polymerizable liquid crystal compositions of Comparative Examples 1 to 3 were poor in any evaluation of the orientation and the unevenness of the film thickness. It was found that the liquid crystal composition could not suppress the occurrence of alignment defects or unevenness in film thickness of the obtained liquid crystal cured film. Further, as described above, the viscosity of the liquid crystal cured film obtained from the polymerizable liquid crystal compositions of Comparative Examples 4 and 5 after 48 hours from the end of mixing could not be measured due to gelation, and the liquid crystal cured film and the retardation were not measured. A film could not be formed.

Claims (10)

A polymerizable liquid crystal compound, a polymerization initiator, a polymerization inhibitor, and a polymerizable liquid crystal composition containing an organic solvent,
The following equation (1)
0.15 ≦ cV ≦ 0.65 (1)
[In the formula, cV is the solid content concentration c (mass fraction) of the polymerizable liquid crystal composition and, after mixing of all the components contained in the polymerizable liquid crystal composition is completed, under a 23 ° C fluorescent lamp (40 W) in a closed container. Represents the product of the viscosity of the polymerizable liquid crystal composition at 23 ° C. and the viscosity V (mPa · s) after 48 hours, where c is 0.07 to 0.15 and V is 1 to 5].
The filling,
The polymerizable liquid crystal compound has the following formula (I)

[Wherein, Ar represents a divalent aromatic group which may have a substituent, and G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group. Wherein the hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group is a halogen atom, an alkyl group having 1 to 4 carbon atoms, or a fluoroalkyl having 1 to 4 carbon atoms. A carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an alkoxy group having 1 to 4 carbon atoms, a cyano group or a nitro group, , A sulfur atom or a nitrogen atom, L ¹ , L ² _, B ¹ and B ² are each independently a single bond or a divalent linking group, and k and l are each independently 0 represents -3 integer satisfying the relation of 1 ≦ k + l, here, if it is 2 ≦ k + l, ^{B 1} and ^{B 2} G ¹ and G ² each may be the same as each other or different, each E ¹ and E ² independently represents an alkanediyl group having 1 to 17 carbon atoms, where the alkanediyl group May be substituted with a halogen atom, -CH _2- contained in the alkanediyl group may be substituted with -O-, -S-, -Si-, ¹ and P ² each independently represents a polymerizable group or a hydrogen atom, at least one is a polymerizable group]
Is a compound represented by
The polymerizable liquid crystal composition, wherein the polymerization initiator is an oxime-based photopolymerization initiator.   The polymerizable liquid crystal composition according to claim 1, wherein the polymerizable liquid crystal compound is a liquid crystal compound having a photopolymerizable group.   The polymerizable liquid crystal composition according to claim 1, wherein a maximum absorption wavelength of the polymerization initiator is 300 to 400 nm.   The polymerizable liquid crystal composition according to any one of claims 1 to 3, wherein the polymerizable liquid crystal compound has a maximum absorption wavelength of 300 to 400 nm.   The polymerizable liquid crystal composition according to any one of claims 1 to 4, wherein the content of the polymerization inhibitor is 0.1 to 10 parts by mass based on 100 parts by mass of the polymerizable liquid crystal compound.   The polymerizable liquid crystal composition according to claim 1, wherein the polymerization inhibitor is a primary antioxidant.   A cured liquid crystal film obtained by curing the polymerizable liquid crystal composition according to claim 1, wherein the polymerizable liquid crystal compound is polymerized in an aligned state.   A retardation film comprising the liquid crystal cured film according to claim 7.   An elliptically polarizing plate, comprising the retardation film according to claim 8 and a polarizing film.   A display device comprising the elliptically polarizing plate according to claim 9.