JP2019151763A - Polymerizable liquid crystal composition - Google Patents

Abstract

To provide a polymerizable liquid crystal composition that, even after long-term storage, prevents alignment defects and uneven thickness from occurring in a resultant liquid crystal cured film.SOLUTION: The present invention provides a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent, satisfying 0.15≤cV≤0.65. [cV is the product of a solid content concentration c (mass fraction) of the polymerizable liquid crystal composition, and a viscosity V(mPa s) at 23°C of the polymerizable liquid crystal composition about 48 hours after mixing of all the components of the polymerizable liquid crystal composition].SELECTED DRAWING: None

Description

  The present invention relates to 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 2017- No. 027058).

JP 2017-027058 A

  In order to continuously form such a liquid crystal cured film, it is necessary to prepare the polymerizable liquid crystal composition and store it for a long time. However, according to the study by 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, so that gelation proceeds. When the polymerizable liquid crystal compound is polymerized in an aligned state after storage, it has been found that alignment defects of the obtained liquid crystal cured film may occur. It was also found that even when the polymerizable liquid crystal compound did not progress to gelation, when a cured liquid crystal film was formed after storage, film thickness unevenness may occur.

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

  As a result of intensive studies to solve the above problems, the present inventor has found that a polymerizable liquid crystal composition containing a polymerizable liquid crystal composition, a polymerization initiator, and an organic solvent has a solid content concentration c ( (Mass fraction) and the viscosity V (mPa · s) at 23 ° C. of the polymerizable liquid crystal composition when 48 hours have elapsed after mixing all the components contained in the composition is 0.15 or more and 0.65 If it is below, it discovered that the said subject could be solved and came to complete this 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,
Following formula (1)
0.15 ≦ cV ≦ 0.65 (1)
[Wherein, cV is the solid content concentration c (mass fraction) of the polymerizable liquid crystal composition and all components contained in the polymerizable liquid crystal composition at 23 ° C. after 48 hours from the end of mixing. Represents the product of viscosity V (mPa · s)
A polymerizable liquid crystal composition satisfying the requirements.
[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 maximum absorption wavelength of the polymerizable liquid crystal compound is 300 to 400 nm.
[5] The polymerizable liquid crystal composition according to any one of [1] to [4], further including 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 liquid crystal cured 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 comprising the elliptically polarizing plate according to [10].

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

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

In the formula (1), the solid content of the polymerizable liquid crystal composition means all components excluding volatile components such as organic solvents in the polymerizable liquid crystal composition, and the solid content concentration c (mass fraction). The solid content relative to the mass of the polymerizable liquid crystal composition 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, Preferably it is 0.05-0.25, Most preferably, it is 0.07-0.15. When the solid content concentration c is in the above range, good applicability of the polymerizable liquid crystal composition can be obtained, and the occurrence of unevenness in the film thickness of the obtained liquid crystal cured film can be easily suppressed.

In the formula (1), the viscosity V indicates the viscosity (mPa · s) at 23 ° C. of the polymerizable liquid crystal composition when 48 hours have elapsed after completion of mixing all the components contained in the polymerizable liquid crystal composition. Examples of the method of mixing the polymerizable liquid crystal composition include stirring, and the time when 48 hours have elapsed after the completion of mixing means the time when 48 hours have elapsed from the time of completion of mixing, for example, stirring. Storage from the end of mixing until 48 hours has passed in a sealed container under a 23 ° C. fluorescent lamp (40 W).
Although viscosity V will not be limited if Formula (1) is satisfy | filled, Preferably it is 1-15 mPa * s, More preferably, it is 1-10 mPa * s, More preferably, it is 1-5 mPa * s. When the viscosity V is not less than the above lower limit value, it is easy to suppress the occurrence of unevenness in the film thickness of the obtained liquid crystal cured film, and when it is equal to or less than the above upper limit value, 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, more preferably 0.20 to 0.57. When cV is not less than the above lower limit value, it is easy to suppress the occurrence of unevenness in the film thickness of the obtained liquid crystal cured film, and when it is not more than the above upper limit value, the occurrence of alignment defects in the obtained liquid crystal cured film is suppressed. Cheap. In addition, when the liquid crystal cured film obtained is a retardation film, if the liquid crystal cured film has uneven thickness, retardation unevenness may occur. Therefore, it can be said that the occurrence of unevenness in film thickness can be suppressed, and the occurrence of unevenness in phase difference can also be suppressed, but the unevenness in film thickness is caused by unevenness in retardation of a liquid crystal cured film, for example, as described in 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. As the polymerizable liquid crystal compound, for example, conventionally in the field of retardation film A known polymerizable liquid crystal compound can be used. The photopolymerizable group refers to a group that can participate in a polymerization reaction by a reactive species generated from a photopolymerization initiator, such as an active radical or an acid. Examples of the photopolymerizable group include a vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, and oxetanyl group. Among them, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable. The thermic liquid crystal may be either a thermotropic liquid crystal or a lyotropic liquid crystal, but the thermotropic liquid crystal is preferred in terms of enabling precise film thickness control. The phase order structure in 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 that satisfy 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) It has π electrons on the direction crossing the major axis direction (a) [crossing direction (b)].
(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 molecular weight present in the major axis direction. Π electron density in the major axis direction (a):
D (πa) = N (πa) / N (Aa) (i)
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 molecular weight present in the cross direction (b) Π electron density in the cross direction (b) of:
D (πb) = N (πb) / N (Ab) (ii)
And
0 ≦ [D (πa) / D (πb)] ≦ 1
[In other words, the π electron density in the cross direction (b) is larger than the π electron density in the major axis direction (a)).
In addition, the polymerizable liquid crystal compound satisfying all of the above (1) to (4) can form a nematic phase by coating on the alignment film and heating to a temperature higher than the phase transition temperature. In the nematic phase formed by aligning the polymerizable liquid crystal compound, the polymerizable liquid crystal compound is usually aligned so that the major axis directions thereof are parallel to each other, and the major axis direction 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 often exhibits reverse wavelength dispersion. Specific examples of the compound satisfying the above characteristics (1) to (4) include, for example, the following formula (I):

The compound represented by these is mentioned.

In 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 having a planarity, and the number of π electrons of the ring structure is [4n + 2] according to the Hückel rule. Here, n represents an integer. In the case where a ring structure is formed by including a heteroatom such as -N = or -S-, the case where the Huckel's rule is satisfied including the non-covalent electron pair on the heteroatom and the aromatic structure is included 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, the hydrogen atom contained in the divalent aromatic group or 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, or carbon. The carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon group which may be substituted with an alkoxy group of 1 to 4 groups, a cyano group or a nitro group is an oxygen atom or a sulfur atom Alternatively, it may be substituted with 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 or different from each other.
E ¹ and E ² each independently represents 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, The —CH ₂ — contained may be substituted with —O—, —S—, or —Si—.
P ¹ and P ² each 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 which may be 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. 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 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 A substituted 1,4-trans-cyclohexanediyl group.
In addition, 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. More preferably, it is a divalent alicyclic hydrocarbon group.

L ¹ and L ² are preferably each independently, preferably 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 —. . Here, R ^a2-1 , R ^a4-1 , and R ^a6-1 each independently represent a single bond, —CH ₂ —, or —CH ₂ CH ₂ —. 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, preferably a single bond, an alkylene group having 1 to 4 carbon atoms, —O—, —S—, —R ^a9 OR ^a10 —, —R ^a11 COOR ^a12 —, —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, more preferably a single bond, —OR ^a10-1 —, —CH ₂ —, —CH ₂ CH ₂ —, ^{—COOR a12-1} —, or OCOR ^a14-1 —. . Here, R ^a10-1 , R ^a12-1 , and R ^a14-1 each independently represent a single bond, —CH ₂ —, or —CH ₂ CH ₂ —. 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 + l ≦ 6 from the viewpoint of expression of inverse wavelength dispersion, preferably k + l = 4, and more preferably k = 2 and l = 2. It is preferable that k = 2 and l = 2 because a symmetrical structure is obtained.

E ¹ and E ² are each independently preferably an alkanediyl group having 1 to 17 carbon atoms, and 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, vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, and oxiranyl group. And an oxetanyl group. Among them, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferable, and acryloyloxy group is more preferable.

  Ar preferably has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle 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 furan ring, benzofuran ring, pyrrole ring, indole ring, thiophene ring, benzothiophene ring, pyridine ring, pyrazine ring, pyrimidine ring, triazole ring, triazine ring, pyrroline ring, imidazole ring, pyrazole ring. , Thiazole ring, benzothiazole ring, thienothiazole ring, oxazole ring, benzoxazole ring, phenanthrolin ring, and the like. Of these, a thiazole ring, a benzothiazole ring, or a benzofuran ring is preferable, and a benzothiazole group is more preferable. In addition, when Ar includes a nitrogen atom, the nitrogen atom preferably has π electrons.

In formula (I), the total number N _π of π electrons contained in the divalent aromatic group represented by Ar is preferably 8 or more, more preferably 10 or more, still more preferably 14 or more, particularly Preferably it is 16 or more. Moreover, Preferably it is 30 or less, More preferably, it is 26 or less, More preferably, it is 24 or less.

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

In formula (Ar-1) to formula (Ar-23), * represents a linking part, and Z ⁰ , Z ¹ and Z ² are each independently a hydrogen atom, a halogen atom, or an alkyl having 1 to 12 carbon atoms. 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, C1-C12 alkylthio group, C1-C12 N-alkylamino group, C2-C12 N, N-dialkylamino group, C1-C12 N-alkylsulfamoyl group or carbon The N, N-dialkylsulfamoyl group represented by Formula 2 to 12 is represented.

Q ¹ , Q ² and Q ³ each independently represent —CR ^{2 ′} R ^{3 ′} —, —S—, —NH—, —NR ^{2 ′} —, —CO— or O—, wherein 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 represents 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 has 4 to 20 carbon atoms and contains at least one hetero atom such as a nitrogen atom, an oxygen atom, a sulfur atom such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, or a benzothiazolyl group. 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 an optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. 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 group derived from a condensed polycyclic aromatic heterocyclic group or an aggregate of aromatic rings.

Z ⁰ , Z ¹ and Z ² are each independently preferably 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, or a cyano group, and Z ¹ and Z ² are more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or 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 formulas (Ar-1) to (Ar-23), formula (Ar-6) and formula (Ar-7) are preferable from the viewpoint of molecular stability.
In 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 that Ar may have, for example, pyrrole ring, imidazole ring, pyrroline ring, pyridine ring, pyrazine ring, pyrimidine ring, indole Ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring and the like. This aromatic heterocyclic group may have a substituent. Y ¹ may be the above-described polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group which may be substituted together with the nitrogen atom to which it is bonded and Z ⁰ . For example, a benzofuran ring, a benzothiazole ring, a benzoxazole ring, etc. are mentioned.

  Among the polymerizable liquid crystal compounds, a polymerizable liquid crystal compound having a maximum absorption wavelength of 300 to 400 nm is preferable. The polymerization initiator contained in the polymerizable liquid crystal composition preferably has an absorption wavelength at 300 to 400 nm, more preferably a maximum absorption wavelength at 300 to 400 nm, and thus absorbs ultraviolet light during storage of the composition. As a result, reactive active species such as active radicals are generated, and the polymerization reaction and gelation of the polymerizable liquid crystal compound may proceed. However, when the polymerizable liquid crystal compound having a maximum absorption wavelength of 300 to 400 nm is contained in the composition as described above, the polymerizable liquid crystal compound absorbs the exposure light even when ultraviolet light is exposed during storage. Generation of reactive species by the photopolymerization initiator and 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 of the obtained liquid crystal cured film Thickness uniformity can be improved. Note that 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 that can dissolve 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. More preferably, it is 85-98 mass parts, More preferably, it is 90-95 mass parts. If 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 liquid crystal cured film. In the present specification, the solid content of the polymerizable liquid crystal composition means all components excluding volatile components such as organic solvents from the 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 reactive species include active species such as radicals, cations, and anions. Among these, from the viewpoint of easy reaction control, a photopolymerization initiator that generates radicals (active radicals) by light irradiation is preferable.

  Examples of the photopolymerization initiator include benzoin compounds, benzophenone compounds, benzyl ketal compounds, α-hydroxy ketone compounds, α-amino ketone 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 (above, BASF Japan Ltd.) ), Sequol BZ, Sequol Z, Sequol BEE (above, Seiko Chemical Co., Ltd.), kayacure BP100 (Nippon Kayaku Co., Ltd.), Kayacure UVI-6992 (Dow), Adekaoptomer SP- 152, Adekaoptomer SP-170, Adekaoptomer N-1717, Adekaoptomer N-1919, Adeka Arcles NCI-831, Adeka Arcles NCI-930 (above, stocks Company ADEKA), TAZ-A, TAZ-PP (above, made by Nippon Siebel Hegner) and TAZ-104 (made by Sanwa Chemical Co., Ltd.). A photoinitiator can be used individually or in combination of 2 or more types.

The photopolymerization initiator maximizes absorption from the viewpoint of fully utilizing the energy emitted from the light source, ensuring a sufficient polymerization rate of the polymerizable liquid crystal compound, and obtaining a cured liquid crystal film having sufficient hardness as a retardation film. The wavelength is preferably 300 to 400 nm, and more preferably 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 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. Also 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 that can dissolve the polymerizable liquid crystal compound, and examples thereof include chloroform.
Among the photopolymerization initiators, α-acetophenone photopolymerization initiators and oxime photopolymerization initiators are preferable.

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

  The oxime photopolymerization initiator generates methyl radicals when irradiated with light. Polymerization of the polymerizable liquid crystal compound in the deep part of the liquid crystal cured film suitably proceeds by this methyl radical. Moreover, it is preferable to use the photoinitiator which can utilize the ultraviolet-ray with a wavelength of 350 nm or more efficiently from a viewpoint that a polymerization reaction in the deep part of a liquid crystal cured film advances more efficiently. As a photopolymerization initiator capable of efficiently using ultraviolet rays having a wavelength of 350 nm or more, a triazine compound or an oxime ester type carbazole compound is preferable, and an oxime ester type carbazole compound is more preferable from the viewpoint of sensitivity. Examples of the oxime ester type carbazole compound include 1,2-octanedione, 1- [4- (phenylthio) -2- (O-benzoyloxime)], ethanone, 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 (above, manufactured by BASF Japan Ltd.), Adekaoptomer N-1919, Adeka Arcles NCI-831 (or more ADEKA Co., Ltd.).

  Although content of a polymerization initiator can be suitably adjusted according to the kind and amount of the polymeric liquid crystal compound contained in a polymeric liquid crystal composition, it is 0.1-30 mass with respect to 100 mass parts of polymeric liquid crystal compounds. Part, preferably 0.5 to 20 parts by weight, and more preferably 1 to 15 parts by weight. When the content of the polymerization initiator is not less 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 not more than the above upper limit, it is easy to improve the long-term storage stability of the polymerizable liquid crystal composition.

<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 according to the polymerizable liquid crystal compound to be 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 Solvent; Aromatic hydrocarbon solvent such as toluene and xylene; Nitrile solvent such as acetonitrile; Tetrahydro Ether solvents such as lan 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 Etc. 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 an ester solvent, a ketone solvent, and an amide solvent.

  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, further preferably 75 to 95 parts by mass, and particularly preferably 85 to 93 parts by mass. . When the content of the organic solvent is within the above range, good coating properties of the polymerizable liquid crystal composition can be obtained, and the occurrence of unevenness in the film thickness of the obtained liquid crystal cured film can be easily suppressed.

<Polymerization inhibitor>
The polymerizable liquid crystal composition of the present invention preferably contains a polymerization inhibitor. The 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 of the polymerizable liquid crystal composition at 23 ° C. after 48 hours has elapsed after 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 increases, the polymerization reaction of the polymerizable liquid crystal compound is suppressed, so that the viscosity V tends to decrease. On the other hand, when the content of the polymerization inhibitor contained in the composition decreases, the polymerization reaction of the polymerizable liquid crystal compound tends to proceed, and thus the viscosity V tends to increase. The viscosity V can also 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 conventionally known polymerization inhibitor can be used in the field of retardation film, and examples thereof include a phenolic antioxidant, an amine antioxidant, a quinone antioxidant, and a nitroso oxidation. Primary antioxidants such as antioxidants; secondary antioxidants such as phosphorus-based antioxidants and sulfur-based antioxidants. A polymerization inhibitor can be used individually or in combination of 2 or more types. Among these, primary antioxidants such as phenolic antioxidants are preferable from the viewpoint of capturing radicals derived from the polymerization initiator, and primary oxidation is performed with a molecular weight of 500 or less from the viewpoint of not inhibiting the polymerization of the liquid crystal cured film after drying. An inhibitor is 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 ester structure or a phosphite ester structure is classified as a phosphorus antioxidant.
Examples of phenolic antioxidants 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) ), Sumilizer (registered trademark) BHT (manufactured by Sumitomo Chemical Co., Ltd.), Sumilizer (registered trademark) GA-80 (manufactured by Sumitomo Chemical Co., Ltd.), (Registered trademark) GS (manufactured by Sumitomo Chemical Co., Ltd.), Cyanox (registered trademark) 1790 (manufactured by Cytec Co., Ltd.) and vitamin E (manufactured by Eisai Co., Ltd.).

  An amine antioxidant is an antioxidant having an amino group in the molecule. Examples of amine-based antioxidants include 1-naphthylamine, phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine, p-nonylphenyl-1-naphthylamine, p-dodecylphenyl-1-naphthylamine, and phenyl-2. -Naphthylamine antioxidants 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 Didecyl such as dodecyl diphenylamine, p, p′-distyryl diphenylamine, p, p′-dimethoxydiphenylamine, 4,4′-bis (4-α, α-dimethylbenzoyl) diphenylamine, p-isopropoxydiphenylamine, 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 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] dioxaphosphine, tris (2,4-di-tert-butylphenyl) phosphite, diphenylisooctyl phosphite, 2,2′-methylenebis (4,6-di-) tert-butylphenyl) octyl phosphite, diphenyl isodecyl phosphite, diphenyl isodecyl phosphite, triphenyl phosphate, tributyl phosphate, distearyl pentaerythritol diphosphite, cyclic neopentanetetrayl bis (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] dioxaphosphine, tris (nonylphenyl) phosphite, tris (mono- and dinonylphenyl mixed) phosphite, diphenyl mono (tridecyl) phosphite, 2,2'-ethylidenebis (4,6- Di-tert-butylphenol) fluorophosphite, phenyl diisodecyl phosphite, tris (2-ethylhexyl) phosphite, tris (isodecyl) phosphite, tris (tridecyl) phosphite, tetrakis (2,4-di-tert-butylphenyl) ) -4,4'-biphenylene-diph Sphonite, 4,4′-isopropylidene diphenyltetraalkyl (C12-C15) diphosphite, 4,4′-butylidenebis (3-methyl-6-tert-butylphenyl) -ditridecyl phosphite, bis (nonylphenyl) Pentaerythritol diphosphite, bis (2,4-di-tert-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 (nonyl attedphenyl) 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, ADK STAB (registered trademark) 329K (manufactured by ADEKA), ADK STAB (registered trademark) PEP36 (manufactured by ADEKA), ADK STAB (registered trademark) PEP-8 (manufactured 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] Dioxaphosphepine) and the like.

  The sulfur-based antioxidant is an antioxidant having a sulfur atom in the molecule. Examples of sulfur-based antioxidants include dialkylthiodipropionate compounds such as dilauryl thiodipropionate, dimyristyl, and distearyl; and β-alkyl mercaptopropionic acids of polyols such as tetrakis [methylene (3-dodecylthio) propionate] methane. An ester compound etc. are mentioned.

  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 100 parts by mass with respect to 100 parts by mass of the polymerizable liquid crystal compound. 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 not less than the above lower limit, the polymerization reaction and gelation of the polymerizable liquid crystal compound during storage can be effectively suppressed, so that 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 value, 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 flattening the liquid crystal cured film obtained by applying the composition. Examples of the leveling agent include a silicone-based leveling agent, a polyacrylate-based leveling agent, and a perfluoroalkyl-based leveling agent. Specifically, DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all are manufactured by Toray Dow Corning Co., Ltd.), 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) Manufactured), Fluorinert (registered trademark) FC-72, FC-40, FC-43, FC-3283 (above, Manufactured by Sumitomo 3M Co., Ltd.), MegaFace (registered trademark) R-08, R-30, R-90, F-410, F-411, F-443, F-445, F-470, F-477, F-479, F-482, F-482 (all of which are manufactured by DIC Corporation), Ftop (trade name) EF301, EF303, EF351, EF352 (all manufactured by Mitsubishi Materials Electronics Chemical Co., Ltd.), Surflon (registered trademark) S-381, S-382, S-383, S-393, SC-101, SC-105, KH -40, SA-100 (all are manufactured by AGC Seimi Chemical Co., Ltd.), trade names E1830, E5844 (manufactured by Daikin Fine Chemical Laboratory), 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 leveling agents and perfluoroalkyl leveling agents are preferable.

  The content of the leveling agent is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass with respect to 100 parts by mass of the polymerizable liquid crystal compound. It is preferable for the leveling agent content to be in the above range because, for example, it becomes easy to horizontally align the polymerizable liquid crystal compound 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; anthracene having a substituent such as anthracene and alkyl ether; phenothiazine; and rubrene. A photosensitizer can be used individually or in combination of 2 or more types. 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. Part.

<Additives>
The polymerizable liquid crystal composition of the present invention may contain additives such as adhesion improvers, mold release agents, stabilizers, colorants such as bluing agents, flame retardants and lubricants. The content of the additive is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass with respect to the mass of the solid content of the polymerizable liquid crystal composition.

  The polymerizable liquid crystal composition of the present invention comprises 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 obtained by polymerizing a polymerizable liquid crystal compound in an aligned state. Since the liquid crystal cured film and the retardation film of the present invention are formed from the polymerizable liquid crystal composition, the liquid crystal cured film and the retardation film can have a uniform film thickness while exhibiting excellent orientation. Therefore, there is no variation in phase difference and excellent optical characteristics are obtained.

  The liquid crystal cured film of the present invention is preferably a film having anisotropy in the three-dimensional refractive index. The three-dimensional refractive index ellipsoid formed by the liquid crystal cured film may have biaxiality, but preferably has uniaxiality. 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 aligned in the horizontal direction with respect to the plane of the liquid crystal cured film, or perpendicular to the plane of the liquid crystal cured film. It may be a vertically aligned liquid crystal cured film obtained by polymerizing polymerizable liquid crystal compounds that are aligned in the direction (film thickness direction of the liquid crystal cured film), or may be a hybrid aligned liquid crystal cured film or a tilted aligned liquid crystal cured film. .

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

In the horizontally aligned liquid crystal cured film, R (λ) that 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 properties represented by 4) and the following formula (5).
100 nm ≦ Re (550) ≦ 160 nm (2)
[In the formula, 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)
[Where Re (450) is the in-plane retardation value for light of wavelength 450 nm, Re (550) is the in-plane retardation value for light of wavelength 550 nm, and Re (650) is the in-plane retardation value for light of wavelength 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. More preferably, it is 0.95 or less, More preferably, it is 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 film thickness d may be adjusted to obtain a desired in-plane retardation value (Re (λ)). . 0.5-5 micrometers is preferable and, as for the thickness of a horizontal alignment liquid crystal cured layer, 1-3 micrometers is more preferable. The thickness of the horizontally aligned liquid crystal cured layer can be measured with an interference film thickness meter, a laser microscope, or a stylus thickness meter. Note that Δn (λ) depends on the molecular structure of the polymerizable liquid crystal compound described later.
Re (λ) = d × Δn (λ) (5)
(In the formula, Re (λ) represents the in-plane retardation value at the wavelength λnm, d represents the film thickness, and Δn (λ) represents the birefringence at the 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 polymerization rate of the liquid crystal cured film is equal to or higher than the above value, the film can have a sufficient degree of curing that can be used for retardation film applications. The polymerization rate can be measured by the method described in the examples.

The liquid crystal cured film of the present invention is preferably formed on a substrate or an alignment film. The retardation film of this invention should just contain the said liquid crystal cured film, may further contain the base material or the orientation film, and it is preferable that the base material and the orientation film are further further included. Such a retardation film comprises the following steps:
A step of applying the polymerizable liquid crystal composition onto a substrate or an alignment film to obtain a coating layer (hereinafter, also referred to as “coating step”),
A step of removing the solvent from the obtained coating layer and aligning 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 Process of obtaining a cured liquid crystal film (hereinafter also referred to as “curing process”)
It can manufacture by the method containing. In addition, when forming a polymeric liquid crystal composition on an alignment film, it is preferable to form this alignment film on a base material.

  In the coating process, the polymerizable liquid crystal composition is coated on a substrate or alignment film, for example, extrusion coating method, direct gravure coating method, reverse gravure coating method, CAP coating method, slit coating method, die coating method. Etc. Moreover, the method of apply | coating using coaters, such as a dip coater, a bar coater, a spin coater, etc. are mentioned. 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 the Roll to Roll format, an alignment film forming composition or the like is applied to a substrate to form an alignment film, and the polymerizable liquid crystal composition may be continuously applied on the obtained alignment film. it can.

As a base material, a glass base material and a film base material are mentioned, A film base material is preferable from a viewpoint of workability, and a long roll-shaped film is more preferable at the point which can be manufactured continuously. Examples of the resin constituting the film substrate include polyolefins such as polyethylene, polypropylene, norbornene polymers, cyclic olefin resins, polyvinyl alcohol, polyethylene terephthalate, polymethacrylates, polyacrylates, triacetylcellulose, and diacetylcellulose. And cellulose esters such as cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyethersulfone; polyetherketone; and resins such as polyphenylene sulfide and polyphenylene oxide.
Examples of the commercially available cellulose ester base material include “Fujitac Film” (manufactured by Fuji Photo Film Co., Ltd.);
Commercially available cyclic olefin-based resins include “Topas” (registered trademark) (manufactured by Ticona (Germany)), “Arton” (registered trademark) (manufactured by JSR Corporation), “ZEONOR” (registered trademark), “ZEONEX” (registered trademark) (manufactured by Nippon Zeon Co., Ltd.) and “Apel” (registered trademark) (manufactured by Mitsui Chemicals, Inc.) can be mentioned. Such a cyclic olefin-based resin can be formed into a substrate by forming a film by a known means such as a solvent casting method or a melt extrusion method. Commercially available cyclic olefin resin base materials can also be used. Commercially available cyclic olefin-based resin base materials include “Essina” (registered trademark), “SCA40” (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), “ZEONOR FILM” (registered trademark) (Nippon Zeon Corporation). And “Arton Film” (registered trademark) (manufactured by JSR Corporation).
The thickness of the substrate is preferably as thin as possible so that it can be handled practically, but if it is too thin, the strength tends to decrease and the processability tends to be poor. The thickness of a base material is 5-300 micrometers normally, Preferably it is 20-200 micrometers. Moreover, the further thinning effect is acquired by peeling a base material and transferring the laminated body of liquid crystal cured film independent or a liquid crystal cured film, and an alignment film.

  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 when the polymerizable liquid crystal composition is applied or the like, and 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 groove alignment film having a concavo-convex 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 preferable in that the orientation direction can be easily controlled.

  Such an alignment film facilitates the alignment of the polymerizable liquid crystal compound. Various orientations such as vertical orientation, horizontal orientation, hybrid orientation, and tilt orientation 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 alignment polymer used for the rubbing alignment film include polyamides and gelatins having an amide bond, polyimides having an imide bond, and polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyacrylamide which are hydrolyzed products thereof. Examples include oxazole, polyethyleneimine, polystyrene, polyvinyl pyrrolidone, polyacrylic acid, and polyacrylic acid esters. The orientation polymers can be used alone or in combination of two or more.

  A 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, By rubbing, an alignment regulating force can be applied.

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

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

  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 alignment film. Examples of the method for removing the solvent contained in the oriented polymer composition include a natural drying method, a ventilation drying method, a heat drying method and a vacuum drying method.

  Examples of the rubbing treatment include a method in which a rubbing cloth is wound and the coating film is brought into contact with a rotating rubbing roll. If masking is performed when the rubbing treatment is performed, a plurality of regions (patterns) having different orientation directions can be formed in the alignment film.

  The photo-alignment film is usually made of a polymer, oligomer or monomer having a photoreactive group. In the case of continuously forming a cured liquid crystal film, a polymer having a molecular weight of 5000 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 formed 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 removing the solvent by drying. 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 polarized light to be irradiated.

  The photoreactive group refers to a group that generates alignment ability when irradiated with light. Specific examples include groups that are involved in photoreactions that are the origin of alignment ability, such as alignment-induced reactions, isomerization reactions, photodimerization reactions, photocrosslinking reactions, or photodecomposition reactions of molecules generated by light irradiation. As the photoreactive group, an unsaturated bond, particularly a group having a double bond is preferable, and a carbon-carbon double bond (C = C bond), a carbon-nitrogen double bond (C = N bond), and 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 preferred.

  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 the photodimerization reaction or the photocrosslinking reaction is preferable in terms of excellent orientation. Among them, a photoreactive group involved in the photodimerization reaction is preferable, and a cinnamoyl group is preferable in that a photoalignment film having a relatively small amount of polarized light irradiation necessary for alignment and having excellent thermal stability and stability over time can be easily obtained. And chalcone groups are preferred. As the polymer having a photoreactive group, a polymer having a cinnamoyl group in which 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 photoalignment film can be adjusted by the type of the polymer or monomer and the thickness of the target photoalignment film, and is at least 0.2% by mass or more. Preferably, the range of 0.3 to 10% by mass is more preferable.

  Examples of the method for applying the composition for forming a photo-alignment film on a substrate include the same methods as those for applying the polymerizable liquid crystal composition on the substrate or the alignment film. Examples of the method for removing the solvent from the applied composition for forming a photo-alignment film include the same method as the method for removing the solvent from the oriented polymer composition.

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

The groove alignment film is a film having a concavo-convex 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 grooves arranged at equal intervals, liquid crystal molecules are aligned in a direction along the groove.
As a method for obtaining a groove alignment film, a method of forming a concavo-convex pattern by performing development and rinsing 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 UV curable resin layer before curing on a sheet-shaped master, transferring the resin layer to a substrate and curing, and a plurality of UV curable resin films before curing formed on the substrate, Examples include a method in which a roll-shaped master having a groove is pressed to form irregularities and then cured.

  Examples of the method for removing the solvent from the coating layer obtained in the coating step in the drying step include natural drying, ventilation drying, heat drying, reduced pressure drying, and a combination thereof. Of these, 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 10 seconds to 20 minutes, more preferably 30 seconds to 10 minutes.

  In the curing step, the polymerizable liquid crystal compound aligned in the drying step can be polymerized 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 according to the type of polymerizable liquid crystal compound (particularly, the type of photopolymerizable functional group possessed by the polymerizable liquid crystal compound), the type of photopolymerization initiator, and the amount thereof. . Specifically, one or more kinds of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays can be used. Among them, ultraviolet light is preferable in that it is easy to control the progress of the polymerization reaction and that a photopolymerization apparatus widely used in this field can be used. It is preferable to select the kind of the liquid crystalline 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 ultrahigh pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, and a wavelength range. Examples include LED light sources that emit light of 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 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and even more preferably 0.1 seconds. ~ 1 minute. When irradiating once or a plurality of times with such ultraviolet irradiation intensity, the integrated light quantity 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 quantity is within this range, sufficient curing of the obtained liquid crystal cured film tends to be obtained, and coloring of the liquid crystal cured film can be prevented.

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

[Elliptically 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 bonding the retardation film and the polarizing film through an adhesive.
In one embodiment of the present invention, when laminating a retardation film on a polarizing film, laminating so that the slow axis (optical axis) of the retardation film and the absorption axis of the polarizing film are substantially 45 °. Is preferred. By laminating so that the slow axis (optical axis) of the retardation film and the absorption axis of the polarizing film are substantially 45 °, a function as an elliptically polarizing plate can be obtained. Note that 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, or a film in which a dye having absorption anisotropy is applied and oriented. Examples of the dye having absorption anisotropy include a dichroic dye.

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

  The film obtained by coating and orienting a dye having absorption anisotropy is a film obtained by coating a composition containing a dichroic dye having liquid crystallinity, or a composition comprising a dichroic dye and a polymerizable liquid crystal compound. Examples thereof include a film obtained by applying a product. The film coated with the pigment having absorption anisotropy is preferably thin, but if it is too thin, the strength is lowered and the processability tends to be inferior. The thickness of the film is usually 20 μm or less, preferably 5 μm or less, and more preferably 0.5 to 3 μm. From the point obtained as a hard film, a film formed by applying a composition containing a dichroic dye and a polymerizable liquid crystal compound and forming a polymer in a state where the polymerizable liquid crystal compound is oriented is preferable, and a 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. 5776063, Japanese Patent No. 5923941, Japanese Patent No. 5987622, Japanese Patent No. 6006485, Japanese Patent No. 6036452, and Japanese Patent No. 6036452. Examples include polarizers described in 6098053, Japanese Patent No. 6132049, and the like.

  In addition, the elliptically polarizing plate of this invention may contain other layers other than a phase difference film, a polarizing film, and an adhesive agent (adhesive agent layer). Examples of other layers include isotropic protective films and hard coat layers.

  The present invention includes a display device including the elliptically polarizing plate. The display device can be obtained by bonding an elliptically polarizing plate, preferably a retardation film of an 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. Display devices include liquid crystal display devices, organic electroluminescence (EL) display devices, inorganic electroluminescence (EL) display devices, touch panel display devices, electron emission display devices (field emission display devices (FED, etc.), surface field emission display devices. (SED)), electronic paper (display device using electronic ink or electrophoretic element), plasma display device, projection display device (grating light valve (GLV) display device, display device having digital micromirror device (DMD)) Etc.) and piezoelectric ceramic displays. The liquid crystal display device includes any of a transmissive liquid crystal display device, a transflective liquid crystal display device, a reflective liquid crystal display device, a direct view liquid crystal display device, a projection liquid crystal display device, and the like. These display devices may be a display device that displays a two-dimensional image, or may be a stereoscopic display device that displays a three-dimensional image. In particular, as a 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 a polarizing film and a retardation film in the formation of an elliptically polarizing plate, or as an adhesive for bonding an elliptical polarizing plate and a display in the formation of a display device, Examples thereof include pressure-sensitive adhesives, dry-solidifying adhesives, and chemically reactive adhesives. Examples of the chemically reactive adhesive include an active energy ray curable adhesive. As an adhesive in the formation of an elliptically polarizing plate, an adhesive layer formed from a pressure-sensitive adhesive, a dry-solidifying adhesive, and an active energy ray-curable adhesive is preferable, and an adhesive in the formation of a display device. As such, a pressure-sensitive adhesive or 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 acrylic polymers, silicone polymers, polyesters, polyurethanes, and polyethers. 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. It is preferable because it does not easily float or peel off under humidifying conditions.

  As an acrylic polymer, (meth) acrylate (hereinafter referred to as (meth) acrylate is a generic term for (meth) acrylate) in which the alkyl group in the ester moiety is an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group or a butyl group. 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 A copolymer with an acrylic monomer is preferred.

  A pressure-sensitive adhesive containing such a copolymer is excellent in adhesiveness, and even when removed after being bonded to a display device, it is relatively easy to remove without causing adhesive residue or the like on the display device. Is preferable. The glass transition temperature of the acrylic polymer is preferably 25 ° C. or less, and more preferably 0 ° C. or less. The mass average molecular weight of such an acrylic polymer is preferably 100,000 or more.

Examples of the solvent include the solvents mentioned as the organic solvent. The pressure-sensitive adhesive may contain a light diffusing agent. The light diffusing agent is an additive that imparts light diffusibility to the pressure-sensitive adhesive, and may be fine particles having a refractive index different from the refractive index of the polymer included 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). Since many of the polymers that the pressure-sensitive adhesive contains as an active ingredient, including acrylic polymers, have a refractive index of about 1.4 to 1.6, the light diffusing agent has a refractive index of 1.2 to 1.8. It is preferable to select appropriately. The refractive index difference 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, or fine particles close to 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 deviation method or 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). Fine particles comprising an organic compound (polymer) include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate / styrene copolymer resin beads (refractive index 1.50). To 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. Examples thereof include resin beads (refractive index: 1.46). The content of the light diffusing agent is usually 3 to 30 parts by mass with respect to 100 parts by mass of the polymer.
Since the thickness of the pressure-sensitive adhesive is determined according to the adhesive force and the like, it is not particularly limited, but is usually 1 to 40 μm. From the viewpoints of workability and durability, the thickness is preferably 3 to 25 μm, more preferably 5 to 20 μm. By setting the thickness of the 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 blurring or blurring of the display image is prevented. It can be made difficult to occur.

The dry-solidifying adhesive may contain a solvent.
The dry-solidifying adhesive contains, as a main component, a polymer of a monomer having a protonic functional group such as a hydroxyl group, a carboxyl group or an amino group and an ethylenically unsaturated group, or a urethane resin. Examples include aldehydes, epoxy compounds, epoxy resins, melamine compounds, zirconia compounds, and compositions containing a curable compound such as a zinc compound. Examples of the polymer of a monomer having a protonic functional group such as a hydroxyl group, a carboxyl group or an amino group and an ethylenically unsaturated group include an ethylene-maleic acid copolymer, an itaconic acid copolymer, an acrylic acid copolymer, and an acrylamide. Examples include copolymers, saponified products of polyvinyl acetate, and polyvinyl alcohol resins.

  Examples of the polyvinyl alcohol resin include polyvinyl alcohol, partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. Can be mentioned. 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 polyester ionomer type urethane resins. The polyester ionomer type urethane resin here is a urethane resin having a polyester skeleton, and a resin in which a small amount of an ionic component (hydrophilic component) is introduced. Since such an ionomer type urethane resin is emulsified in water without using an emulsifier and becomes an emulsion, it can be an aqueous adhesive. When a polyester ionomer type urethane resin is used, it is effective to blend a water-soluble epoxy compound as a crosslinking agent.

  Examples of the epoxy resin include a polyamide epoxy resin obtained by reacting a polyalkylenepolyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid and epichlorohydrin. Commercially available products of such polyamide epoxy resins include “Smiles Resin (registered trademark) 650” and “Smiles Resin 675” (manufactured by Sumika Chemtex Co., Ltd.), “WS-525” (manufactured by Nippon PMC Co., Ltd.). Etc. When mix | blending an epoxy resin, the addition amount is 1-100 mass parts normally with respect to 100 mass parts of polyvinyl alcohol-type resin, Preferably it is 1-50 mass parts.

  The thickness of the adhesive layer formed from the dry-solidifying adhesive is usually 0.001 to 5 μm, preferably 0.01 to 2 μm, more preferably 0.01 to 0.5 μm. is there. If the adhesive layer formed from the dry-solidifying adhesive is too thick, the optically anisotropic layer tends to be defective in appearance.

The active energy ray-curable adhesive may contain a solvent. An active energy ray-curable adhesive is an adhesive that cures upon irradiation with active energy rays.
Examples of the active energy ray-curable adhesive include a cationic polymerizable adhesive containing an epoxy compound and a cationic polymerization initiator, a radical polymerizable adhesive containing an acrylic curing component and a radical polymerization initiator, and an epoxy compound. Contains both a cationic polymerizable curing component such as an acrylic compound and a radical polymerizable curing component such as an acrylic compound, and further contains an adhesive containing a cationic polymerization initiator and a radical polymerization initiator, and these polymerization initiators. For example, an adhesive that is cured by irradiating an electron beam.

Among them, radically polymerizable active energy ray-curable adhesives containing an acrylic curing component and a radical polymerization initiator, and cationic polymerizable active energy ray-curable adhesives containing an epoxy compound and a cationic polymerization initiator are provided. 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 above-described photopolymerization initiators. Commercially available cationic polymerization initiators include “Kayarad” (registered trademark) series (manufactured by Nippon Kayaku Co., Ltd.), “Syracure UVI” series (manufactured by Dow Chemical Co., Ltd.), “CPI” series (manufactured by San Apro Corporation), “TAZ”, “BBI” and “DTS” (manufactured by Midori Chemical Co., Ltd.), “Adekaoptomer” series (manufactured by ADEKA Co., Ltd.), “RHODORSIL” (registered trademark) (manufactured by Rhodia Co., Ltd.) It is done. Content of a radical polymerization initiator and a cationic polymerization initiator is 0.5-20 mass parts normally with respect to 100 mass parts of active energy ray hardening-type adhesives, Preferably it is 1-15 mass parts.

  The active energy ray-curable adhesive further contains an ion trap agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, an antifoaming agent, and the like. May be.

  In this specification, an active energy ray is defined as an energy ray capable of generating an active species by decomposing a compound that generates 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 preferable. Preferable ultraviolet irradiation conditions are the same as the polymerization of the polymerizable liquid crystal compound described above.

Hereinafter, the present invention will be described in more detail with reference to examples. Unless otherwise specified, “%” and “parts” in the examples are% by mass and part by mass.
The apparatus, measurement method, and evaluation method used in the examples are as follows.

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

[Measurement of viscosity]
In Examples and Comparative Examples, the viscosity V after 48 hours from the completion of mixing all the components contained in the polymerizable liquid crystal composition and the viscosity of the solvent used are vibration viscometer VM-10A manufactured by CBC Materials Co., Ltd. -L was used in accordance with “JIS 8803Z: 2011 Liquid Viscosity Measurement Method”.

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

[Measurement of polymerization rate]
Measurement of infrared total reflection absorption spectrum (“Model 670-IR” manufactured by Agilent) (incident angle 45 °) was performed on the liquid crystal cured films obtained in Examples and Comparative Examples, and the measurement results obtained ( Value of peak intensity I (1) derived from in-plane bending vibration (1408 cm ⁻¹ ) of ethylenically 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.
A thin layer of the polymerizable liquid crystal compound (A) was obtained by dropping a solution obtained by dissolving the polymerizable liquid crystal compound (A) in chloroform onto a germanium crystal and drying it. 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 result.
From the values of P ′ and P0, the polymerization rate defined by (1−P ′ / P0) × 100 was calculated. The larger this value is, the higher the degree of cure of the liquid crystal cured film is.

[Evaluation of orientation]
The liquid crystal cured films obtained in Examples and Comparative Examples were observed at a magnification of 400 times using a polarizing microscope (BX51, manufactured by Olympus Corporation). Those with good orientation were marked with “◯”, and those with poor orientation such as a poor orientation on the surface were marked with “x”.

[Evaluation of film thickness unevenness]
A pair of linear polarizers were stacked on the light table so as to be crossed Nicols. 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. Due to the uniformity in the observed image (uniformity of phase difference), “O” indicates that the entire surface is substantially uniform and no unevenness is observed, and “X” indicates that unevenness is observed.

[Example 1]
<Preparation of composition for forming photo-alignment film>
A composition for forming a photo-alignment film (1) is prepared by mixing 5 parts of a photo-alignment material having the following structure and 95 parts of cyclopentanone (solvent) as components and stirring the resulting mixture at 80 ° C. for 1 hour. 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), and the following photopolymerization 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 was 9%, and the mixture was stirred at 80 ° C. for 1 hour, whereby the polymerizable liquid crystal composition (1). Got.
After completion of the stirring, that is, after completion of mixing of all components contained in the polymerizable liquid crystal composition, the polymerizable liquid crystal composition (1) was stored in a sealed container under a 23 ° C. fluorescent lamp (40 W) for 48 hours. The viscosity V at 23 ° C. of the polymerizable liquid crystal composition after the lapse of 48 hours after 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 2010-31223 A. 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 parts 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 in the following addition amounts to 100 parts of the polymerizable liquid crystal compound (A).
Oxime ester type carbazole compound (Irgacure OXE-03 (manufactured by BASF Japan Ltd.)): 7.5 parts with respect to 100 parts of the polymerizable liquid crystal compound (A). In addition, the maximum absorption wavelength of this 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. In addition, the maximum absorption wavelength of this initiator measured in chloroform is 320 nm.

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

[Example 2]
A polymerizable liquid crystal composition (2), 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 13%.

[Example 3]
A polymerizable liquid crystal composition (3), 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 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 cyclopentanone. The viscosity of cyclopentanone at 23 ° C. was 1.08 mPa · s.

[Example 5]
Except that the polymerizable liquid crystal compound is LC242 (manufactured by BASF Japan Ltd.), the solvent is propylene glycol monomethyl ether acetate (PGMEA), the solid content concentration is 13%, and the dibutylhydroxytoluene content is 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 5%.

[Example 7]
A polymerizable liquid crystal composition (7), a cured liquid crystal film, and a retardation film were obtained in the same manner as in Example 1 except that the polymerizable liquid crystal composition was a polymerizable liquid crystal compound (B) having the following structure. . The polymerizable liquid crystal compound (B) was synthesized by the method described in JP2010-24438A. 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 1-3]
Polymerizable liquid crystal compositions (8) to (10), liquid crystal in the same manner as in Example 1, except that the solid content concentration and the content of dibutylhydroxytoluene (polymerization inhibitor) are as shown in Table 1. A cured film and a retardation film were obtained. The viscosity at 23 ° C. immediately after 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 is LC242 (manufactured by BASF Japan Ltd.), the solvent is propylene glycol monomethyl ether acetate (PGMEA), the solid content concentration is 13%, and the content of dibutylhydroxytoluene (polymerization inhibitor) is shown in Table 1. Polymerizable liquid crystal compositions (11) and (12) were obtained in the same manner as in Example 1 except for the description. When the polymerizable liquid crystal compositions (11) and (12) are stored in a sealed container under a 23 ° C. fluorescent lamp (40 W) for 48 hours, gelation proceeds and viscosity cannot be measured. A liquid crystal cured film and a retardation film could not be formed.

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

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

Claims (11)

A polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent,
Following formula (1)
0.15 ≦ cV ≦ 0.65 (1)
[Wherein cV is the solid content concentration c (mass fraction) of the polymerizable liquid crystal composition and 23 ° C. of the polymerizable liquid crystal composition after 48 hours have elapsed after mixing all the components contained in the polymerizable liquid crystal composition. Represents the product of viscosity V (mPa · s)
A polymerizable liquid crystal composition satisfying the requirements.   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 or 2, wherein a maximum absorption wavelength of the polymerization initiator is 300 to 400 nm.   The polymerizable liquid crystal composition according to claim 1, wherein the maximum absorption wavelength of the polymerizable liquid crystal compound is 300 to 400 nm.   Furthermore, the polymeric liquid crystal composition in any one of Claims 1-4 containing a polymerization inhibitor.   The polymerizable liquid crystal composition according to claim 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.   The polymerizable liquid crystal composition according to claim 5 or 6, wherein the polymerization inhibitor is a primary antioxidant.   A liquid crystal cured 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 8.   An elliptically polarizing plate comprising the retardation film according to claim 9 and a polarizing film.   A display device comprising the elliptically polarizing plate according to claim 10.