TW201938603A - Polymerizable liquid crystal composition - Google Patents

Abstract

This polymerizable liquid crystal composition comprises a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent and satisfies formula (1): 0.15 ≤ cV ≤ 0.65 [in the formula, cV represents a product of the solids concentration c (mass fraction) of the polymerizable liquid crystal composition and the viscosity V (mPa.s) at 23 DEG C of the polymerizable liquid crystal composition after the elapse of 48 hours from the completion of mixing of all of the components in the polymerizable liquid crystal composition]. In addition, the polymerizable liquid crystal compound is preferably a photopolymerizable group-bearing liquid crystal compound.

Description

Polymerizable liquid crystal composition

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

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 containing a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent has been known from the viewpoint of thinning (for example, Japanese Patent No. (Publication 2017-027058).
[Prior technical literature]
[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2017-027058

[Problems to be solved by the invention]

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 inventors, when the polymerizable liquid crystal composition is stored for a long period of time, it is known that the polymerizable liquid crystal compound in the composition reacts due to the influence of light, and therefore gels. If the polymerizable liquid crystal composition is polymerized after storage, When the liquid crystal compound is polymerized in an aligned state, alignment defects of the obtained liquid crystal cured film may occur. It is also known that, even if the polymerizable liquid crystal compound is not gelated, if a liquid crystal cured film is formed after storage, uneven film thickness may occur.

Therefore, an object of the present invention is to provide a polymerizable liquid crystal composition capable of suppressing occurrence of alignment defects and unevenness in film thickness of the obtained liquid crystal cured film even after long-term storage, and curing the polymerizable liquid crystal composition. A liquid crystal cured film, a retardation film including the liquid crystal cured film, an elliptical polarizing plate including the retardation film and a polarizing film, and a display device including the elliptical polarizing plate.
[Technical means to solve the problem]

The present inventors conducted diligent research in order to solve the above-mentioned problems, and as a result, found that if the polymerizable liquid crystal composition containing a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent, the solid component concentration c (Mass fraction), the product of the viscosity V (mPa · s) at 23 ° C of the polymerizable liquid crystal composition at the time of 48 hours after the end of mixing with all the components contained in the composition is 0.15 or more and 0.65 In the following, the above problems can be solved, and the present invention has been completed. That is, the following are included in the present invention.

[1] A polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent, and satisfying the following formula (1)
0.15 ≦ cV ≦ 0.65 (1)
[In the formula, cV represents the solid content concentration c (mass fraction) of the polymerizable liquid crystal composition, and the polymerizable liquid crystal composition at the time when 48 hours have elapsed after all the components contained in the polymerizable liquid crystal composition are mixed. Product of viscosity V (mPa · s) at 23 ℃].
[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 maximum absorption wavelength of the polymerization initiator is 300 to 400 nm.
[4] The polymerizable liquid crystal composition according to any one of [1] to [3], wherein the polymerizable liquid crystal compound has a maximum absorption wavelength of 300 to 400 nm.
[5] The polymerizable liquid crystal composition according to any one of [1] to [4], further comprising a polymerization inhibitor.
[6] The polymerizable liquid crystal composition according to [5], wherein the content of the polymerization inhibitor is 0.1 to 10 parts by mass based on 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 formed by curing the polymerizable liquid crystal composition according to any one of [1] to [7], and 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 and the polarizing film according to [9].
[11] A display device including the elliptical polarizer according to [10].
[Effect of the invention]

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

[Polymerizable liquid crystal composition]
The polymerizable liquid crystal composition of the present invention includes a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent, and satisfies the following formula (1)
0.15 ≦ cV ≦ 0.65 (1)
[In the formula, cV represents the solid content concentration c (mass fraction) of the polymerizable liquid crystal composition, and the polymerizable liquid crystal composition at the time when 48 hours have elapsed after all the components contained in the polymerizable liquid crystal composition are mixed. Product of viscosity V (mPa · s) at 23 ℃].
If the relationship of the formula (1) is satisfied, it is unexpected that even after long-term storage, it is possible to suppress the occurrence of alignment defects and uneven thickness of the obtained liquid crystal cured film. Therefore, the liquid crystal cured film obtained by curing the polymerizable liquid crystal composition of the present invention can have excellent alignment and uniform film thickness. On the other hand, if cV is less than 0.15, the thickness of the obtained liquid crystal cured film may be uneven. When cV exceeds 0.65, alignment defects of the obtained liquid crystal cured film may occur.

In the formula (1), the solid content of the polymerizable liquid crystal composition means all components in the polymerizable liquid crystal composition except for volatile components such as organic solvents, and the so-called solid content concentration c (mass fraction), The content of the solid component relative to the mass of the polymerizable liquid crystal composition is a value obtained by dividing the mass of the solid component contained in the polymerizable liquid crystal composition by the mass of the polymerizable liquid crystal composition.
The solid content component concentration c (mass fraction) of the polymerizable liquid crystal composition is not limited as long as it satisfies formula (1), preferably 0.01 to 0.5, more preferably 0.03 to 0.3, and still more preferably 0.05 to 0.25, especially It is preferably 0.07 to 0.15. When the solid component concentration c is in the above range, good coatability of the polymerizable liquid crystal composition can be obtained, and the occurrence of uneven film thickness of the obtained liquid crystal cured film can be easily suppressed.

In the formula (1), the viscosity V represents the viscosity (mPa · s) of the polymerizable liquid crystal composition at 23 ° C. when 48 hours have elapsed after all the components contained in the polymerizable liquid crystal composition have been mixed. As a method of mixing the polymerizable liquid crystal composition, for example, stirring is mentioned. When 48 hours have elapsed after the mixing is completed, it means a time that has passed 48 hours from the time when the mixing is completed, for example, the stirring. Storage from the end of mixing to 48 hours elapsed was performed in a closed container at 23 ° C under a fluorescent lamp (40 W).
The viscosity V is not limited as long as it satisfies the formula (1), and is preferably 1 to 15 mPa · s, more preferably 1 to 10 mPa · s, and still more preferably 1 to 5 mPa · s. If the viscosity V is greater than or equal to the above lower limit value, it is easy to suppress the occurrence of uneven film thickness of the obtained liquid crystal cured film, and if it is less than or equal to the above upper limit value, it is easy to suppress the occurrence of alignment defects of the obtained liquid crystal cured film.

In formula (1), cV, which is the product of the above-mentioned c and the above-mentioned V, is preferably 0.17 to 0.60, and more preferably 0.20 to 0.57. If cV is greater than or equal to the above lower limit value, it is easy to suppress the occurrence of uneven film thickness of the obtained liquid crystal cured film, and if it is less than or equal to the above upper limit value, it is easy to suppress the occurrence of alignment defects of the obtained liquid crystal cured film. Furthermore, in the case where the obtained liquid crystal cured film is a retardation film, if there is unevenness in film thickness of the liquid crystal cured film, unevenness in retardation 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. For example, the unevenness in film thickness can be measured by measuring the unevenness in phase difference of the liquid crystal cured film as described in the examples. And evaluate.

<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, it can be used in the field of a retardation film, for example. A conventionally known polymerizable liquid crystal compound. The photopolymerizable group refers to a group that can participate in a polymerization reaction by a reactive species such as a living radical or an acid generated from a photopolymerization initiator. Examples of the photopolymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloxy group, a methacrylic acid group, and an oxetanyl group. , Oxetanyl and the like. Among these, acryloxy, methacryloxy, ethyleneoxy, oxetanyl, and oxetanyl are preferred, and acryloxy is more preferred. The liquid crystallinity may be either a thermotropic liquid crystal or a liquid crystalline liquid crystal. In terms of enabling dense film thickness control, a thermotropic liquid crystal is preferred. The phase order structure in the nematic liquid crystal may be a nematic liquid crystal or a smectic liquid crystal. The polymerizable liquid crystal compound can be used alone or in combination of two or more kinds.

Examples of the polymerizable liquid crystal compound include compounds satisfying all of the following (1) to (4).
(1) Compounds that can form a nematic phase;
(2) The polymerizable liquid crystal compound has π electrons in the long axis direction (a).
(3) There are π electrons in a direction [crossing direction (b)] that intersects with the major axis direction (a).
(4) A total of π electrons existing in the long axis direction (a) is set to N (πa), and a total of molecular weights existing in the long axis direction is set to N (Aa). Π-electron density of the long axis direction (a) of the liquid crystal compound:
D (πa) = N (πa) / N (Aa) (i),
Polymerizability as defined by the following formula (ii) with the total of π electrons present in the cross direction (b) as N (πb) and the total of molecular weights present in the cross direction (b) as N (Ab) Π electron density in the cross direction (b) of the liquid crystal compound:
D (πb) = N (πb) / N (Ab) (ii)
Be in
0 ≦ [D (πa) / D (πb)] ≦ 1
The relationship [that is, the π electron density in the cross direction (b) is greater than the π electron density in the long axis direction (a)].
Furthermore, the polymerizable liquid crystal compound satisfying all of the above (1) to (4) can be formed on the alignment film by heating it to a phase transition temperature or higher to form a nematic phase. In the nematic phase formed by the alignment of the polymerizable liquid crystal compound, the alignment is generally performed so that the long axis directions of the polymerizable liquid crystal compound are parallel to each other, and the long axis direction becomes the alignment direction of the nematic phase.

In general, polymerizable liquid crystal compounds having the above-mentioned characteristics often exhibit inverse wavelength dispersibility. Specific examples of the compound satisfying the above-mentioned characteristics (1) to (4) include the following formula (I):
[Chemical 1]

The indicated compound.

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

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

L ¹ and L ² are 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 represent an alkyl group or hydrogen atom having 1 to 4 carbon atoms. L ¹ and L ² are each independently 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 further preferably a single bond, -O-, -CH ₂ CH _2- , -COO-, -COOCH ₂ CH _2- , or -OCO-.

B ¹ and B ² are 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 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 any one of a single bond, —CH ₂ —, and —CH ₂ CH ₂ —. B ¹ and B ² are each independently further preferably a single bond, -O-, -CH ₂ CH _2- , -COO-, -COOCH ₂ CH _2- , -OCO-, or -OCOCH ₂ CH _2- .

From the viewpoint of exhibiting inverse wavelength dispersion, k and l are preferably in a range of 2 ≦ k + l ≦ 6, more preferably k + l = 4, more preferably k = 2 and l = 2. If k = 2 and l = 2, it is preferable to form a symmetrical structure.

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 epoxy groups, vinyl groups, vinyloxy groups, 1-chlorovinyl groups, isopropenyl groups, 4-vinylphenyl groups, allyloxy groups, and methyl Propylene fluorenyloxy, oxetanyl, and oxetanyl. Among these, acryloxy, methacryloxy, ethyleneoxy, oxetanyl, and oxetanyl are preferred, and acryloxy is more preferred.

Ar preferably has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring, and a benzene ring and a naphthalene ring are preferred. Examples of the aromatic heterocyclic ring include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyridine ring, a pyrimidine ring, a triazole ring, a tricyclic ring, and a pyrrole. A phthaloline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thiazolothiazole ring, an oxazole ring, a benzoxazole ring, a phenanthroline ring, and the like. Among these, it is preferable to have a thiazole ring, a benzothiazole ring, or a benzofuran ring, and it is more preferable to have a benzothiazolyl group. When a nitrogen atom is contained in Ar, the nitrogen atom preferably has a π electron.

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

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

[Chemical 2]

In the formulae (Ar-1) to (Ar-23), the * symbol represents a connecting portion, and Z ⁰ , Z ¹ and Z ² each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, Nitro, alkylsulfinyl having 1 to 12 carbons, alkylsulfinyl having 1 to 12 carbons, carboxyl, fluoroalkyl having 1 to 12 carbons, alkoxy having 1 to 6 carbons, Alkylthio groups having 1 to 12 carbon atoms, N-alkylamino groups having 1 to 12 carbon atoms, N, N-dialkylamino groups having 2 to 12 carbon atoms, and N-alkylamines having 1 to 12 carbon atoms Sulfonyl or N, N-dialkylamine sulfonyl having 2 to 12 carbons.

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

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

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

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 in Y ¹ , Y ² and Y ³ include an aromatic hydrocarbon group having 6 to 20 carbon atoms such as phenyl, naphthyl, anthracenyl, phenanthryl, and biphenyl. Phenyl, Naphthyl is more preferably phenyl. Examples of the aromatic heterocyclic group include a carbon number of 4 to 5 including heteroatoms such as furyl, pyrrolyl, thienyl, pyridyl, thiazolyl, and benzothiazolyl, including at least one nitrogen atom, oxygen atom, and sulfur atom. The aromatic heterocyclic group of 20 is preferably a furyl group, a thienyl group, a pyridyl group, a thiazolyl group, or a benzothiazolyl group.

Y ¹ , Y ² and Y ³ may each independently be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from a collection of aromatic rings. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from a collection 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, and Z ^{0 is} further preferable A hydrogen atom, an alkyl group having 1 to 12 carbon atoms, and a cyano group, and Z ¹ and Z ^{2 are more} preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, and a cyano group.

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

Among the formulae (Ar-1) to (Ar-23), from the viewpoint of molecular stability, the formulae (Ar-6) and (Ar-7) are preferred.
In the formulae (Ar-16) to (Ar-23), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom and Z ⁰ to which it is bonded. Examples of the aromatic heterocyclic group include those described above as the aromatic heterocyclic ring that Ar may have, and examples thereof include a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrimidine ring, a pyrimidine ring, and an indole ring. , Quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring and the like. The aromatic heterocyclic group may have a substituent. In addition, Y ¹ may form a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted with the nitrogen atom and Z ⁰ to which Y ¹ is bonded. Examples thereof include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring.

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, and more preferably has an absorption wavelength at 300 to 400 nm. Therefore, it absorbs ultraviolet light during storage of the composition As a result, reactive species such as active radicals are generated, and the polymerization reaction and gelation of the polymerizable liquid crystal compound may proceed. However, if a 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 if it is exposed to ultraviolet light during storage, which is effective The generation of the reactive species caused by the photopolymerization initiator and the progress of the polymerization reaction and gelation of the polymerizable liquid crystal compound caused by the reactive species are suppressed. Therefore, if a polymerizable liquid crystal compound having a maximum absorption wavelength of 300 to 400 nm is included in the polymerizable liquid crystal composition, it is advantageous in terms of long-term stability of the polymerizable liquid crystal composition, and the alignment of the obtained liquid crystal cured film can be improved. And film thickness uniformity. The maximum absorption wavelength of the polymerizable liquid crystal compound can be measured in a solvent using an ultraviolet-visible spectrophotometer. This solvent is a solvent which can dissolve a 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, and more preferably 85 to 99 parts by mass based on the solid content of the polymerizable liquid crystal composition. 98 parts by mass, and more preferably 90 to 95 parts by mass. When the content of the polymerizable liquid crystal compound is within the above range, it is advantageous from the viewpoint of the alignment of the obtained liquid crystal cured film. In addition, in this specification, the solid content component of a polymerizable liquid crystal composition means all components except the volatile component, such as an organic solvent, from a polymerizable liquid crystal composition.

<Polymerization initiator>
The polymerizable liquid crystal composition of the present invention contains a polymerization initiator. The polymerization initiator is a compound that generates a reactive species by the action of heat or light, and can start a polymerization reaction such as a polymerizable liquid crystal compound. Examples of the reactive species include reactive species such as a radical, a cation, and an anion. Among them, a photopolymerization initiator that generates radicals (living radicals) by irradiation with light is preferred from the viewpoint of easy reaction control.

Examples of the photopolymerization initiator include a benzoin compound, a benzophenone compound, a benzophenone ketal compound, an α-hydroxy ketone compound, an α-amino ketone compound, a tertiary compound, a sulfonium salt, and a sulfonium salt. Specifically, Irgacure (registered trademark) 907, Yan Jia solid 184, Yan Jia solid 651, Yan Jia solid 819, Yan Jia solid 250, Yan Jia solid 369, Yan Jia solid 379, Yan Jia solid Solid 127, Yanjiagu 2959, Yanjiagu 754, Yanjiagu 379EG (above manufactured by BASF Japan Co., Ltd.), Seikuol BZ, Seikuol Z, Seikuol BEE (above manufactured by Seiko Chemical Co., Ltd.), Kayaku (kayacure) BP100 (manufactured by Nippon Kayaku Co., Ltd.), Kayagu UVI-6992 (manufactured by Dow), Adeka Optomer SP-152, Adeka Optomer SP-170, Adeka Optomer N-1717, Adeka Optomer N-1919, Adeka arc LUZ NCI-831, Adeka arc LUZ NCI-930 (above manufactured by ADEKA Co., Ltd.), TAZ-A, TAZ-PP (above manufactured by Nihon Siber Hegner) and TAZ-104 (made by Sanwa Chemical Co., Ltd.) . The photopolymerization initiator can be used alone or in combination of two or more.

From the viewpoint of making full use of the energy emitted from the light source to ensure a sufficient polymerization rate of the polymerizable liquid crystal compound, and to obtain a liquid crystal cured film having sufficient hardness as a retardation film, the photopolymerization initiator preferably has great absorption. The wavelength is 300 to 400 nm, and more preferably 300 to 380 nm. On the other hand, if a polymerizable liquid crystal compound having a maximum absorption wavelength of 300 to 400 nm is contained in the composition as described above, the generation of reactive species caused by the photopolymerization initiator during long-term storage can be effectively suppressed. And the polymerization reaction and gelation of the polymerizable liquid crystal compound caused by the reactive species proceed. From this viewpoint, a photopolymerization initiator having a maximum absorption wavelength of 300 to 400 nm can be preferably used. The maximum absorption wavelength of the photopolymerization initiator can be measured in a solvent using an ultraviolet-visible spectrophotometer. This solvent is a solvent which can dissolve a polymerizable liquid crystal compound, and examples thereof include chloroform.
Among the photopolymerization initiators, an α-acetophenone-based photopolymerization initiator and an oxime-based photopolymerization initiator are preferred.

Examples of the α-acetophenone-based photopolymerization initiator include 2-methyl-2-olinyl-1- (4-methylthiophenyl) propane-1-one and 2-dimethylamine 2- (4-Phenylphenyl) -2-benzylbutane-1-one and 2-dimethylamino-1- (4-Phenylphenyl) -2- (4-methylbenzene Methylmethyl) butane-1-one and the like, more preferably 2-methyl-2-olinyl-1- (4-methylthiophenyl) propane-1-one and 2-dimethylamino- 1- (4-Phenylphenyl) -2-benzylbutane-1-one. Examples of commercially available products of the α-acetophenone-based photopolymerization initiator include Yanjiagu 369, 379EG, and 907 (manufactured by BASF Japan) and Seikuol BEE (manufactured by Seiko Chemical Co., Ltd.).

The oxime-based photopolymerization initiator generates a methyl radical by irradiating light. Polymerization of the polymerizable liquid crystal compound in the deep portion of the liquid crystal cured film is preferably performed by the methyl radical. From the viewpoint of more efficiently performing the polymerization reaction in the deep portion of the liquid crystal cured film, it is preferable to use a photopolymerization initiator capable of efficiently utilizing ultraviolet rays having a wavelength of 350 nm or more. As a photopolymerization initiator capable of efficiently using ultraviolet rays having a wavelength of 350 nm or more, a tri-compound or an oxime ester-type carbazole compound is preferable, and from the viewpoint of sensitivity, an oxime ester-type carbazole compound is more preferable. Examples of the oxime ester type carbazole compound include 1,2-octanedione, 1- [4- (phenylthio) 2- (O-benzyloxime)], ethyl ketone, 1- [9 -Ethyl-6- (2-methylbenzylidene) -9H-carbazol-3-yl] -1- (O-acetamoxime) and the like. Examples of commercially available oxime ester carbazole compounds include: Yanjiagu OXE-01, Yanjiagu OXE-02, Yanjiagu OXE-03 (above manufactured by BASF Japan Co., Ltd.), and Adeka Optomer N- 1919, Adeka arc LUZ NCI-831 (above manufactured by ADEKA Co., Ltd.), etc.

The content of the polymerization initiator can be appropriately adjusted according to the type and amount of the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition, and is preferably 0.1 to 30 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound. Preferably it is 0.5-20 mass parts, More preferably, it is 1-15 mass parts. When the content of the polymerization initiator is at least the above lower limit value, the reaction of the polymerizable group proceeds sufficiently, and the polymerization rate can be increased. When the content of the polymerization initiator is equal to or less than the above-mentioned upper limit value, it is easy to improve the long-term storage stability of the polymerizable liquid crystal composition.

＜ Organic solvents ＞
The polymerizable liquid crystal composition of the present invention contains an organic solvent. The organic solvent is preferably a solvent that dissolves the polymerizable liquid crystal compound and is inactive to the polymerization reaction of the polymerizable liquid crystal compound, as long as it is appropriately selected according to the polymerizable liquid crystal compound used.
Specific examples include 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, Ester solvents such as ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and Ketone solvents such as methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane ; Chlorine-containing solvents such as chloroform and chlorobenzene; dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidone, etc. Amine-based solvents. These organic solvents may be used alone or in combination of two or more. Among these, from the viewpoint of film coating, it is preferred to use at least one selected from the group consisting of alcohol solvents, ester solvents, ketone solvents, chlorine-containing solvents, amidine-based solvents, and aromatic hydrocarbon solvents for polymerization. From the viewpoint of the solubility of the liquid crystal compound, it is more preferable to use at least one selected from the group consisting of an ester solvent, a ketone solvent, and an amidine-based 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, still more preferably 75 to 95 parts by mass, and even more preferably 85 to 93. Parts by mass. When the content of the organic solvent is within the above range, good coatability of the polymerizable liquid crystal composition can be obtained, and it is easy to suppress the occurrence of uneven film thickness of the obtained liquid crystal cured film.

<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, it is possible to control the temperature of the polymerizable liquid crystal composition at 23 ° C. when 48 hours have passed after the mixing of all the components contained in the polymerizable liquid crystal composition. The above viscosity V. When the content of the polymerization inhibitor contained in the composition is increased, the polymerization reaction of the polymerizable liquid crystal compound is suppressed, so that the viscosity V tends to be small. On the other hand, if the content of the polymerization inhibitor contained in the composition is reduced, the polymerization reaction of the polymerizable liquid crystal compound tends to proceed, so that the above-mentioned viscosity V tends to increase. In addition, the viscosity V may be controlled by appropriately adjusting the types and amounts of the organic solvent, the polymerization initiator, and the polymerizable liquid crystal composition.

As the polymerization inhibitor, a polymerization inhibitor previously known in the field of retardation films can be used. Examples thereof include phenol-based antioxidants, amine-based antioxidants, quinone-based antioxidants, and nitroso-based antioxidants. Primary antioxidants; secondary antioxidants such as phosphorus-based antioxidants and sulfur-based antioxidants. The polymerization inhibitor may be used alone or in combination of two or more kinds. Among these, from the viewpoint of capturing radicals derived from the polymerization initiator, primary antioxidants such as phenol-based antioxidants are preferred, and from the viewpoint of not hindering the polymerization of the liquid crystal cured film after drying, it is more preferred. It is a primary antioxidant with a molecular weight of 500 or less.

The phenolic antioxidant is an antioxidant having a phenolic hydroxyl group in the molecule, and preferably has an alkyl group in the ortho position of the phenolic hydroxyl group. In this specification, an antioxidant having both a phenolic hydroxyl group and a phosphate structure or a phosphite structure is classified as a phosphorus-based antioxidant.
Examples of the phenol-based antioxidant include 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane and 4,4'-butylene-bis (3 -Methyl-6-tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, Acrylic acid 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl ester, (tetra [methylene-3- (3,5 -Di-third-butyl-4-hydroxyphenyl) propionate] methane, pentaerythritol tetra [3- (3,5-di-third-butyl-4-hydroxyphenyl) propionate], 3- (3,5-Di-third-butyl-4-hydroxyphenyl) octadecyl propionate, 3,3 ', 3'',5,5', 5 ''-hexa-third-butyl -a, a ', a''-(mesitylene-2,4,6-triyl) tri-p-cresol, 1,3,5-tris (3,5-di-third-butyl-4 -Hydroxybenzyl) -1,3,5-tri-2,4,6 (1H, 3H, 5H) -trione, 1,3,5-tri ((4-thirdbutyl-3-hydroxy- 2,6-xylyl) methyl) -1,3,5-tri-2,4,6 (1H, 3H, 5H) -trione, thiodiethylidenebis (3- (3,5 -Di-third-butyl-4-hydroxyphenyl) propionate], 3,5-bis (1,1-dimethylethyl) -4-hydroxy C7-C9 side chain alkyl ester of phenylpropionate , 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-butylaniline) -1,3,5-tri, 3,9-bis (2 -(3- (3-Third-butyl-4-hydroxy-5-methylphenyl) propanyloxy) -1,1-dimethylethyl) -2,4,8,10-tetraoxy Heterospiro (5,5) undecane, dibutylhydroxytoluene (2,6-di-third-butyl-p-cresol, sometimes referred to as BHT), Sumilizer (registered trademark) BHT (Sumitomo Chemical Co., Ltd. )), Sumilizer (registered trademark) GA-80 (manufactured by Sumitomo Chemical Co., Ltd.), Sumilizer (registered trademark) GS (manufactured by Sumitomo Chemical Co., Ltd.), Cyanox (registered trademark) 1790 (made by Cytec) Vitamin E (manufactured by Eisai).

The so-called amine antioxidant is an antioxidant having an amine group in the molecule. Examples of the amine-based antioxidant include 1-naphthylamine, phenyl-1-naphthylamine, p-octylphenyl-1-naphthylamine, p-nonylphenyl-1-naphthylamine, and Naphthylamine-based antioxidants such as dodecylphenyl-1-naphthylamine, phenyl-2-naphthylamine; N, N'-diisopropyl-p-phenylenediamine, N, N'-di Isobutyl-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- Phenylenediamine, phenylhexyl-p-phenylenediamine, phenyloctyl-p-phenylenediamine, and other phenylenediamine-based antioxidants; dipyridylamine, diphenylamine, p, p'-di-n-butyl Diphenylamine, p, p'-di-third-butyldiphenylamine, p, p'-di-third-pentyldiphenylamine, p, p'-dioctyldiphenylamine , P, p'-dinonyldiphenylamine, p, p'-didecyldiphenylamine, p, p'-di-dodecyldiphenylamine, p, p'-diphenyl Vinyl diphenylamine, p, p'-dimethoxydiphenylamine, 4,4'-bis (4-α, α-dimethylbenzylidene) diphenylamine, p-isopropyl Oxydiphenylamine, di Diphenylamine-based antioxidants such as pyridylamine; phenothia, N-methyl phenothia, N-ethyl phenothia, 3,7-dioctyl phenothia, phenothlenate, phenoselenazine Isorphine antioxidants.

The phosphorus-based antioxidant is an antioxidant having a phosphate structure or a phosphite structure. Examples of the phosphorus-based antioxidant include 6- [3- (3-third-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-th Tributyldibenzo [d, f] [1,3,2] dioxaphosphacycloheptene, tris (2,4-di-third-butylphenyl) phosphite, diphenyl phosphite Isooctyl, 2,2'-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, diphenyl isodecyl phosphite, diphenyl isodecyl phosphite , Triphenyl phosphate, tributyl phosphate, distearyl pentaerythritol diphosphite, cyclic neopentane tetrayl bis (2,6-di-third-butyl-4-methylphenyl) phosphite Ester, 6- [3- (3-Third-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butylbenzo [d, f] [1,3,2] Dioxaphosphoheptene, tris (nonylphenyl) phosphite, tris (mono- & dinonylphenyl mixture) phosphite, diphenyl phosphite Mono (tridecyl) ester, 2,2'-ethylenebis (4,6-di-third-butylphenol) fluorophosphite, phenyl diisodecyl phosphite, tris (2 -Ethylhexyl) ester, tris (isodecyl) phosphite, tris (tridecyl) phosphite, tetra (2,4-di-tert-butylphenyl) -4,4'- Biphenylene-bis-phosphonite, 4,4'-isopropylidenediphenyltetraalkyl (C12-C15) diphosphite, 4,4'-butylene bis (3- Methyl-6-tert-butylphenyl) -didecyl ester, bis (nonylphenyl) pentaerythritol diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol-di- Phosphite, cyclic neopentane tetraylbis (2,6-di-third-butyl-4-methylphenyl-phosphite), 1,1,3-tris (2-methyl-4 -Di-tridecyl phosphite-5-third butylphenyl) butane, tetrakis (2,4-di-third butyl-5-methylphenyl) -4,4'-bi Phenylene diphosphite, tris (2-ethylhexyl) phosphite, triisodecyl phosphite, tristearyl phosphite, phenyl diisodecyl phosphite, trithiophosphite tris Lauryl ester, distearyl pentaerythritol diphosphite, tris (nonylated phenyl) phosphite (TRIS (NONYLATED PHENYL) PHOSPHITE)), tri [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-dimethyl) Ethyl) -6-methylphenyl) ethyl ester phosphorous acid, Adekastab (registered trademark) 329K (manufactured by ADEKA), Adekastab (registered trademark) ) PEP36 (manufactured by ADEKA), Adekastab (registered trademark) PEP-8 (manufactured by ADEKA), Sandstab (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-third-butyl-4-hydroxy-5-methylphenyl) Propoxy] -2,4,8,10-tetra-tert-butyldibenzo [d, f] [1,3,2] dioxaphosphacycloheptene and the like.

The so-called sulfur-based antioxidant is an antioxidant having a sulfur atom in the molecule. Examples of the sulfur-based antioxidant include dialkyl thiodipropionate compounds such as dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate; Β-alkyl mercaptopropionate compounds of polyhydric alcohols such as tetra [methylene (3-dodecylthio) propionate] methane and the like.

When the polymerizable liquid crystal composition contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.1 to 10 parts by mass, more preferably 0.15 to 7 parts by mass, and more preferably 100 parts by mass of the polymerizable liquid crystal compound. It is 0.2 to 5 parts by mass, and particularly preferably 0.2 to 1 part by mass. When the content of the polymerization inhibitor is greater than or equal to the above-mentioned lower limit value, the polymerization reaction and gelation of the polymerizable liquid crystal compound during storage can be effectively suppressed, and thus the occurrence of alignment defects of the obtained liquid crystal cured film is easily suppressed. When the content of the polymerization inhibitor is equal to or less 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 the function of adjusting the fluidity of the polymerizable liquid crystal composition and making the liquid crystal cured film obtained by applying the composition more flat. Examples of the leveling agent include a polysiloxane-based leveling agent, a polyacrylate-based leveling agent, and a perfluoroalkyl-based leveling agent. Specific examples include: DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all of which are manufactured by Dow Corning Toray), KP321, KP323, KP324, KP326, KP340 , KP341, X22-161A, KF6001 (all of which are manufactured by Shin-Etsu Chemical Industry Co., Ltd.), TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF-4446, TSF4452, TSF4460 (all of which are contracted by Momentive Performance Materials Japan) (Manufactured), Fluorinert (registered trademark) FC-72, Fluorinert FC-40, Fluorinert FC-43, Fluorinert FC-3283 (all of which are manufactured by Sumitomo 3M), Megafac (registered trademark) R-08, Megafac R- 30, Megafac R-90, Megafac F-410, Megafac F-411, Megafac F-443, Megafac F-445, Megafac F-470, Megafac F-477, Megafac F-479, Megafac F-482, Megafac F- 483 (all of which are manufactured by DIC), Eftop (trade name) EF301, Eftop EF303, Eftop EF351, Eftop EF352 (all of which are manufactured by Mitsubishi Materials Electronic Chemicals (stock)), Surflon (registered trademark) S-381 Surflon S-382, Surflon S-383, Surf lon S-393, Surflon SC-101, Surflon SC-105, KH-40, SA-100 (all of which are manufactured by AGC Seimi Chemical), trade name E1830, trade name E5844 (Daikin Institute of Precision Chemistry ( )), BM-1000, BM-1100, BYK-352, BYK-353, and BYK-361N (all are trade names: BM Chemie). These leveling agents can be used alone or in combination of two or more. Among these, polyacrylate-based leveling agents and perfluoroalkyl-based leveling agents are preferred.

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

＜ Photosensitizers ＞
The polymerizable liquid crystal composition of the present invention may contain a photosensitizer. Photosensitizers can increase the sensitivity of photopolymerization initiators. Examples of the photosensitizer include ketone and 9-oxysulfur. And other ketones; anthracene and anthracene with alkyl ether and other substituents; phenanthrene; and rubrene. The photosensitizer can be used alone or in combination of two or more. The content of the photosensitizer is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and still more preferably 0.1 to 3 parts by mass, with respect to 100 parts by mass of the polymerizable liquid crystal compound.

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

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

[Liquid crystal hardened 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. This liquid crystal cured film is a cured film obtained by polymerizing a polymerizable liquid crystal compound in an aligned state. The liquid crystal cured film and the retardation film of the present invention are formed of the polymerizable liquid crystal composition, and therefore exhibit excellent alignment and have a uniform film thickness. Therefore, there is no deviation in phase difference, and it has excellent optical characteristics.

The liquid crystal cured film of the present invention is preferably a film having an anisotropic three-dimensional refractive index. The three-dimensional refractive index ellipsoid formed by the liquid crystal hardened 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 aligned in a horizontal direction with respect to the plane of the liquid crystal cured film, or may be a vertical direction with respect to the plane of the liquid crystal cured film ( The liquid crystal cured film may be a vertically aligned liquid crystal cured film formed by polymerizing a polymerizable liquid crystal compound in an aligned state. The liquid crystal cured film may also be a mixed alignment liquid crystal cured film or an oblique alignment liquid crystal cured film.

In a preferred aspect of the present invention, the liquid crystal cured film of the present invention is a liquid crystal cured film obtained by curing the polymerizable liquid crystal composition, and is a polymerization state in which the liquid crystal cured film is aligned in a horizontal direction with respect to the plane of the liquid crystal cured film. Horizontal alignment liquid crystal cured film formed by polymerizing a liquid crystal compound.

The horizontal alignment liquid crystal cured film preferably has an in-plane phase difference with respect to light having a wavelength of λ nm, that is, R (λ) satisfies the optical characteristics shown in the following formula (2), and more preferably satisfies the following formula (3), Optical characteristics represented by the following formula (4).
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)
[In the formula, Re (450) represents the in-plane phase difference value for the light with a wavelength of 450 nm, Re (550) represents the in-plane phase difference value for the light with a wavelength of 550 nm, and Re (650) represents the In-plane phase difference of light]
When the "Re (450) / Re (550)" of the liquid crystal cured film exceeds 1.0, light leakage on the short wavelength side of the elliptical polarizing plate including the liquid crystal cured layer tends to increase. It is more preferably 0.95 or less, and still more preferably 0.92 or less.

The in-plane retardation value of the liquid crystal hardened layer can be adjusted by the thickness of the liquid crystal hardened layer. The in-plane phase difference value is determined by the following formula (5). To obtain the required in-plane phase difference value (Re (λ)), it is only necessary to adjust Δn (λ) and the film thickness d. The thickness of the horizontal alignment liquid crystal hardened layer is preferably 0.5 to 5 μm, and more preferably 1 to 3 μm. The thickness of the horizontal alignment liquid crystal hardened layer can be measured by an interference film thickness meter, a laser microscope, or a stylus film thickness meter. In addition, Δn (λ) depends on the molecular structure of the polymerizable liquid crystal compound described below.
Re (λ) = d × Δn (λ) ... (5)
(In the formula, Re (λ) represents the in-plane phase difference value at the wavelength λ nm, d represents the film thickness, and Δn (λ) represents the complex refractive index at the wavelength λ nm.

The polymerization rate of the liquid crystal cured film is preferably 70% or more, more preferably 75% or more, and even more preferably 80% or more. When the polymerization rate of the liquid crystal cured film is equal to or higher than the above value, it 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 the present invention may include the above-mentioned liquid crystal cured film, and may further include a substrate or an alignment film, and preferably further includes a substrate and an alignment film. Such a retardation film can be manufactured by a method including the following steps:
A step of applying the polymerizable liquid crystal composition on a substrate or an alignment film to obtain a coating layer (hereinafter also referred to as a "coating step");
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 to obtain A step of curing a liquid crystal film (hereinafter also referred to as a "curing step").
When the polymerizable liquid crystal composition is formed on an alignment film, the alignment film is preferably formed on a substrate.

In the coating step, examples of a method for coating the polymerizable liquid crystal composition on a substrate or an alignment film include an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a CAP. Coating method, slit coating method, nozzle coating method, and the like. Moreover, the method of coating using a coating machine, such as a dip coater, a bar coater, and a spin coater, etc. are mentioned. Among these, in terms of continuous coating in a roll-to-roll format, a CAP coating method, an inkjet method, a dip coating method, a slit coating method, and a die are preferred. Nozzle coating method and coating method using a bar coater. In the case of coating in a roll-to-roll format, an alignment film may be formed by applying a composition for forming an alignment film to a substrate, and the polymerizable liquid crystal composition may be continuously applied to the obtained alignment film.

Examples of the substrate include a glass substrate and a film substrate. In terms of processability, a film substrate is preferred, and in terms of continuous production, a long roll film is more preferred. Examples of the resin constituting the film substrate include polyolefins such as polyethylene, polypropylene, and norbornene polymers; cyclic olefin resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid Esters; polyacrylates; cellulose esters such as triethyl cellulose, diethyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polyfluorene; polyetherfluorene; polyetherketone ; Resins such as polyphenylene sulfide and polyphenylene ether.
Examples of commercially available cellulose ester substrates include: "Fujitac Film" (manufactured by Fuji Photo Film Co., Ltd.); "KC8UX2M", "KC8UY", and "KC4UY" (above manufactured by Konica Minolta Opto Co., Ltd.), etc. .
Examples of commercially available cyclic olefin resins include "Topas" (registered trademark) (manufactured by Ticona (Germany)), "ARTON" (registered trademark) (manufactured by JSR Corporation), and "ZEONOR" (registered trademark) ), "ZEONEX" (registered trademark) (above manufactured by Japan Zeon Corporation) and "APEL" (registered trademark) (Mitsui Chemical Co., Ltd.). Such a cyclic olefin-based resin can be formed into a substrate by a known method such as a solvent casting method, a melt extrusion method, and the like. A commercially available cyclic olefin-based resin substrate may be used. Examples of commercially available cyclic olefin-based resin substrates include "S-SINA" (registered trademark), "SCA40" (registered trademark) (above manufactured by Sekisui Chemical Industry Co., Ltd.), and "ZEONOR FILM" (registered (Trademark) (made by Japan Zeon Corporation) and "ARTON FILM" (registered trademark) (made by JSR Corporation).
The thickness of the substrate is preferably thin in terms of quality that can be used for practical operations. However, if the thickness is too thin, the strength is lowered and the workability tends to be poor. The thickness of the substrate is usually 5 to 300 μm, and preferably 20 to 200 μm. In addition, by peeling off the base material, the liquid crystal cured film or the laminated body of the liquid crystal cured film and the alignment film can be transferred separately to obtain a further thinning effect.

The so-called alignment film is one having an alignment restriction force that aligns the polymerizable liquid crystal compound in a desired direction. As the alignment film, those having solvent resistance that do not dissolve due to application of the polymerizable liquid crystal composition, etc., and those having heat resistance for removal of the solvent or heat treatment of the alignment of the polymerizable liquid crystal compound described below are preferred. . Examples of the alignment film include a friction alignment film, a photo-alignment film, a groove alignment film having a concave-convex pattern or a plurality of grooves on its surface, and an extension film. When it is applied to a long roll-shaped film, a photo-alignment film is preferable because it can easily control the alignment direction.

Such an alignment film facilitates the alignment of the polymerizable liquid crystal compound. In addition, various alignments such as vertical alignment, horizontal alignment, hybrid alignment, and oblique alignment can be controlled according to the type of the alignment film, friction conditions, or light irradiation conditions.

The film thickness of the alignment film is usually 10 to 10,000 nm, preferably 10 to 1000 nm, and further preferably 50 to 300 nm.

Examples of the alignment polymer used for the friction alignment film include polyamines or gelatins having a fluorene bond, polyimide having a fluorimide bond, and polyamic acid and a polymer thereof which are hydrolysates thereof. Vinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylates. The alignment polymer may be used alone or in combination of two or more.

The rubbing alignment film can generally be coated with a composition (hereinafter also referred to as an alignment polymer composition) obtained by dissolving an alignment polymer in a solvent, removing the solvent to form a coating film, and rubbing the coating. The film is clothed to give an alignment restricting force.

The concentration of the alignment polymer in the alignment polymer composition may be such that the alignment polymer is completely dissolved in the solvent. The content of the alignment polymer with respect to the alignment polymer composition is preferably 0.1 to 20% by mass, and more preferably 0.1 to 10% by mass.

Aligned polymer compositions are commercially available. Examples of commercially available alignment polymer compositions include Sunever (registered trademark, manufactured by Nissan Chemical Industries, Ltd.), Optomer (registered trademark, manufactured by JSR (corporation)), and the like.

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

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

The photo-alignment film usually contains a polymer or oligomer or monomer having a photoreactive group. In the case where a liquid crystal cured film is continuously formed, a polymer having a molecular weight of 5,000 or more is preferable from the viewpoint of solvent resistance and the like, and a polymerizable liquid crystal compound has a (meth) acrylfluorenyl group from the viewpoint of affinity. In this case, an acrylic polymer is preferable. The photo-alignment film can be coated on a substrate by applying a composition (hereinafter also referred to as a "photo-alignment film-forming composition") containing a polymer or oligomer or a monomer and a solvent having a photoreactive group to a substrate. It is obtained by drying and removing the solvent and irradiating with polarized light (preferably polarized UV). The light alignment film can arbitrarily control the direction of the alignment limiting force by selecting the polarization direction of the polarized light to be irradiated, which is more preferable in this respect.

The photoreactive group refers to a group that generates alignment ability by light irradiation. Specifically, the bases involved in the following reactions can be cited: the orientation-inducing reaction of molecules generated by light irradiation, the isomerization reaction, the photodimerization reaction, the photocrosslinking reaction, or the photodecomposition reaction, etc., which become the origin of the alignment ability Photoreaction. The photoreactive group is preferably a group having an unsaturated bond, especially a double bond, and particularly preferably a group selected from a carbon-carbon double bond (C = C bond) and a carbon-nitrogen double bond (C = N bond) A base of at least one of the group consisting of a nitrogen-nitrogen double bond (N = N bond) and a carbon-oxygen double bond (C = O bond).

Examples of the photoreactive group having a C = C bond include vinyl, polyalkenyl, fluorenyl, styrylpyridyl, styrylpyridinyl, chalcone, and cinnamyl. Examples of the photoreactive group having a C = N bond include a group having a structure such as an aromatic Schiff base and an aromatic fluorene. Examples of the photoreactive group having an N = N bond include an azophenyl group, an azonaphthyl group, an aromatic heterocyclic azo group, a bisazo group, a methylamino group, and an oxazobenzene structure. The base. 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 substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, and halogenated alkyl.

The group participating in the photodimerization reaction or the photocrosslinking reaction is preferable in terms of excellent alignment. Among them, a photoreactive group that participates in a photodimerization reaction is preferred, and a photoalignment film that is relatively easy to obtain a relatively small amount of polarized light irradiation for alignment and excellent in thermal stability or time stability is preferred Cinnamonyl and chalcone. As the polymer having a photoreactive group, it is particularly preferred that the polymer has a cinnamic acid group having a cinnamic acid structure or a cinnamic acid ester structure at the terminal portion of the side chain of the polymer.

The content of the polymer or monomer having a photoreactive group in the composition for forming a photo-alignment film can be adjusted according to the type of polymer or monomer or the thickness of the target photo-alignment film, and is preferably at least 0.2% by mass The above is more preferably in the range of 0.3 to 10% by mass.

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

When the polarized light is irradiated, the polarized light may be directly irradiated to a person who has removed the solvent from the composition for forming a photo-alignment film coated on a substrate, or may be irradiated with polarized light from the substrate side so that the polarized light is transmitted through the substrate and irradiated. form. The polarized light is preferably substantially parallel light. The wavelength of the polarized light to be irradiated is preferably a wavelength region in which a polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet rays) having a wavelength in a 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, KrF, and ArF ultraviolet lasers. Among them, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are preferred due to their relatively large luminous intensity of ultraviolet light at a wavelength of 313 nm. By irradiating the light from the light source with an appropriate polarizing element, polarized UV can be irradiated. Examples of the polarizing element include a polarizing filter, a polarizing chirp such as Glan-Thompson, and Glan Taylor, and a wire grid. Among these, from the viewpoints of an increase in area and heat resistance, a wire grid type polarizing element is preferred. Furthermore, if masking is performed during rubbing or polarized light irradiation, a plurality of regions (patterns) with different directions of liquid crystal alignment may be formed.

The groove alignment film is a film having a concave-convex pattern or a plurality of grooves (grooves) on the surface of the film. When a polymerizable liquid crystal compound is applied to a film having a plurality of linear grooves arranged at equal intervals, the liquid crystal molecules are aligned in a direction along the grooves.
Examples of the method for obtaining the groove alignment film include a method of forming a concave-convex pattern by exposing the surface of the photosensitive polyimide film through an exposure mask having a slit having a pattern shape, and then developing and rinsing it. Method; a method of forming a layer of UV-curing resin before hardening on a plate-like master having grooves on its surface, and moving the resin layer to the substrate to harden; and The method of pressing a roll-shaped master disk having a plurality of grooves to form irregularities, and then curing the film.

Examples of the method for removing the solvent from the coating layer obtained by the coating step in the drying step include a method of natural drying, ventilation drying, heat drying, reduced pressure drying, and a combination thereof. Among them, natural drying or heat drying is preferred. The drying temperature is preferably in the range of 0 to 200 ° C, more preferably in the range of 20 to 150 ° C, and even more preferably in the range of 50 to 130 ° C. The drying time is preferably 10 seconds to 20 minutes, and more preferably 30 seconds to 10 minutes.

In the hardening step, the polymerization of the polymerizable liquid crystal compound aligned by the drying step can be performed by a known method for polymerizing a compound having a polymerizable group, and for example, light irradiated with active energy rays can be used. polymerization.

The active energy ray to be irradiated is appropriately selected according to the type of the polymerizable liquid crystal compound (especially the type of the photopolymerizable functional group of the polymerizable liquid crystal compound), the type of the 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 mentioned. Among them, in terms of the ease of controlling the progress of the polymerization reaction and the point that a wide range of users in the field can be used as the photopolymerization device, ultraviolet light is preferred, and photopolymerization by ultraviolet light is preferred. Select the type of polymerizable liquid crystal compound.

Examples of the light source of the active energy ray include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, and emission wavelength ranges. 380 ～ 440 nm light LED (light emitting diode) light source, chemical lamp, black light lamp, microwave excited mercury lamp, metal halide lamp, etc.

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 activation of the photopolymerization initiator. The time for irradiating light is usually from 0.1 seconds to 10 minutes, preferably from 0.1 seconds to 5 minutes, more preferably from 0.1 seconds to 3 minutes, and even more preferably from 0.1 seconds to 1 minute. If it is irradiated once or plural times with such an ultraviolet irradiation intensity, the cumulative light amount is 10 to 3,000 mJ / cm ² , preferably 50 to 2,000 mJ / cm ² , and more preferably 100 to 1,000 mJ / cm ² . When the cumulative light amount is within this range, the obtained liquid crystal cured film tends to be sufficiently cured, and coloration 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, and 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 film thickness meter.

[Elliptical polarizing plate and display device]
The elliptical polarizing plate of the present invention includes the retardation film and the 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 a polarizing film is laminated with a retardation film, it is preferred that the retardation film (optical axis) of the retardation film and the absorption axis of the polarizing film be substantially 45 °. Build up. By laminating such that the retardation axis (optical axis) of the retardation film and the absorption axis of the polarizing film become substantially 45 °, the function as an elliptically polarizing plate can be obtained. It should be noted that the substantially 45 ° is usually in the range of 45 ± 5 °.

The polarizing film includes a polarizing element having a polarizing function. Examples of the polarizing element include a stretched film to which a pigment having an anisotropic absorption property is adsorbed, and a film coated and aligned to have a pigment having an anisotropic absorption property. Examples of the dye having absorption anisotropy include a dichroic dye.

An stretched film having adsorbed anisotropic pigment is usually produced through the following steps: a step of uniaxially stretching a polyvinyl alcohol-based resin film, and dyeing the polyvinyl alcohol-based resin film with a dichroic dye. A step of causing the dichroic pigment to be adsorbed; a step of treating a polyvinyl alcohol-based resin film to which the dichroic pigment is adsorbed; The polarizing element obtained in this way was bonded to a transparent protective film, thereby obtaining a polarizing film. Examples of the dichroic dye include iodine or a dichroic organic dye. Examples of the dichroic organic dye include a dichroic direct dye containing a diazo compound such as C.I. Direct Red 39, and a dichroic direct dye containing a compound such as trisazo or tetrasazo. The thickness of the polarizing element obtained by uniaxially stretching the polyvinyl alcohol resin film as described above, using a dichroic dye, boric acid treatment, washing with water, and drying is preferably 5 to 40 μm.

Examples of a film coated with a pigment having an anisotropic absorption orientation include a film obtained by coating a composition containing a dichroic pigment having liquid crystallinity, or a combination containing a dichroic pigment and a polymerizable liquid crystal compound. Film and so on. The film coated with an anisotropic pigment is preferably thin, but if it is too thin, the strength is reduced and the workability tends to be poor. The thickness of the film is usually 20 μm or less, preferably 5 μm or less, and more preferably 0.5 to 3 μm. In terms of being obtainable as a hard film, a film obtained by coating a composition containing a dichroic pigment and a polymerizable liquid crystal compound and forming a polymer in a state where the polymerizable liquid crystal compound is aligned is preferable. In terms of obtaining higher polarizing performance, it is more preferable that the polymerizable liquid crystal compound has a smectic liquid crystal phase and forms a polymer in a smectic liquid crystal phase. Specific examples of such a polarizing element include Japanese Patent No. 4719156, Japanese Patent No. 4937252, Japanese Patent No. 5776063, Japanese Patent No. 5923941, Japanese Patent No. 5962762, Japanese Patent No. 6006485, and Japanese Patent. Polarizing elements described in No. 6036452, Japanese Patent No. 6098053, Japanese Patent No. 6132049, and the like.

Furthermore, the elliptically polarizing plate of the present invention may include other layers besides a retardation film, a polarizing film, and an adhesive (adhesive layer). Examples of the other layer include an isotropic protective film and a hard coat layer.

The present invention includes a display device including the above-mentioned 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. The display device is a device having a display mechanism, and includes a light emitting element or a light emitting device as a light emitting source. Examples of the display device include a liquid crystal display device, an organic electroluminescence (EL) display device, an inorganic electroluminescence (EL) display device, a touch panel display device, and an electron emission display device (field emission display device (FED, etc.)). , Surface-conduction electron emission display device (SED)), electronic paper (display device using electronic ink or electrophoretic element), plasma display device, projection display device (grating light valve (GLV) display device, digital micromirror device) (DMD) display devices, 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, and a projection liquid crystal display device. These display devices may be display devices that display two-dimensional images, or stereo display devices that display three-dimensional images. Especially 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 preferred.

It can be used as an adhesive for attaching a polarizing film and a retardation film in the formation of an elliptically polarizing plate, or an adhesive for attaching an elliptically polarizing plate and a display device in the formation of a display device. Examples include pressure-sensitive adhesives, dry-curing adhesives, and chemically reactive adhesives. Examples of the chemical reaction-type adhesive include an active energy ray-curable adhesive. As an adhesive in forming an elliptical polarizing plate, an adhesive layer formed of a pressure-sensitive adhesive, a dry-curing adhesive, and an active energy ray-curable adhesive is preferably used as an adhesive in forming a display device. The agent is preferably a pressure-sensitive adhesive or an active energy ray-curable adhesive.

Pressure-sensitive adhesives typically include polymers and may include solvents.
Examples of the polymer include acrylic polymers, silicone polymers, polyesters, polyurethanes, and polyethers. Among them, an acrylic adhesive containing an acrylic polymer is excellent in optical transparency, has moderate wetting or cohesiveness, and excellent adhesion, and further has high weather resistance or heat resistance. Under heating or humidifying conditions It is not likely to cause bulging or peeling, and is therefore preferred.

The acrylic polymer is preferably a (meth) acrylic acid ester having an alkyl group having an alkyl group of 1 to 20 carbon atoms such as methyl, ethyl, or butyl (hereinafter, acrylate or methacrylic acid may be used) Esters are collectively referred to as (meth) acrylates, and acrylic acid and methacrylic acid are collectively referred to as (meth) acrylic acid), and (meth) acrylic acid (meth) A copolymer of acrylic monomers.

A pressure-sensitive adhesive containing such a copolymer is preferable because it has excellent adhesion and can be removed relatively easily when it is attached to a display device without removing paste residues from the display device. The glass transition temperature of the acrylic polymer is preferably 25 ° C or lower, and more preferably 0 ° C or lower. The mass average molecular weight of such an acrylic polymer is preferably 100,000 or more.

Examples of the solvent include the solvents listed 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 adhesive, as long as the particles have a refractive index different from that of the polymer contained in the adhesive. Examples of the light diffusing agent include fine particles containing an inorganic compound and fine particles containing an organic compound (polymer). Most polymers including an acrylic polymer as an active ingredient have a refractive index of about 1.4 to 1.6. Therefore, it is preferable to appropriately select a light diffusing agent having a refractive index of 1.2 to 1.8. The refractive index difference between the polymer and the light diffusing agent contained in the adhesive as an active ingredient is usually 0.01 or more, and from the viewpoint of brightness and display property of the display device, it is preferably 0.01 to 0.2. The fine particles used as the light diffusing agent are preferably spherical fine particles, spherical and nearly monodisperse fine particles, and more preferably fine particles having an average particle diameter of 2 to 6 μm. The refractive index is measured by a usual minimum declination method or an Abbe refractometer.
Examples of the fine particles containing an inorganic compound include alumina (refractive index 1.76) and silica (refractive index 1.45). Examples of the fine particles containing an organic compound (polymer) include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), and methyl methacrylate / styrene copolymer resin beads (refractive index). 1.50 ～ 1.59), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1.46), and silicone beads (Refractive index 1.46). The content of the light diffusing agent is usually 3 to 30 parts by mass based on 100 parts by mass of the polymer.
The thickness of the pressure-sensitive adhesive is determined according to its adhesion, etc., and is not particularly limited, but is usually 1 to 40 μm. In terms of processability and durability, the thickness is preferably 3 to 25 μm, and more preferably 5 to 20 μm. By setting the thickness of the adhesive layer formed by the adhesive to 5 to 20 μm, the brightness can be maintained when the display device is viewed from the front or the display device is viewed from an oblique direction, and halo or blurry.

The dry-curable adhesive may include a solvent.
Examples of the dry-curing type adhesive include a polymer containing a monomer having a protic functional group such as a hydroxyl group, a carboxyl group, or an amine group and an ethylenically unsaturated group, or a urethane resin as a main component, and further a polyaldehyde. , Epoxy compounds, epoxy resins, melamine compounds, zirconia compounds, and combinations of cross-linking agents such as zinc compounds or hardening compounds. Examples of the polymer of a monomer having a protonic functional group such as a hydroxyl group, a carboxyl group, or an amine group and an ethylenically unsaturated group include an ethylene-maleic acid copolymer, an itaconic acid copolymer, an acrylic copolymer, and propylene. Ammonium copolymer, saponification of polyvinyl acetate, and polyvinyl alcohol resin.

Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol, partially saponified polyvinyl alcohol, fully saponified polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, acetoacetic acid-modified polyvinyl alcohol, and methylol-modified poly (vinyl alcohol). Vinyl alcohol and amine-modified polyvinyl alcohol. The content of the polyvinyl alcohol resin in the water-based adhesive is usually 1 to 10 parts by mass, and preferably 1 to 5 parts by mass with respect to 100 parts by mass of water.

Examples of the urethane resin include polyester-based ionic polymer-type urethane resins. Here, the polyester-based ionic polymer-type urethane resin is a urethane resin having a polyester skeleton and a small amount of an ionic component (hydrophilic component) introduced therein. This ionic polymer type urethane resin is emulsified in water without using an emulsifier to form an emulsion, so it can be used as an aqueous adhesive. When using a polyester-based ionic polymer urethane resin, it is effective to mix a water-soluble epoxy compound as a crosslinking agent.

Examples of the epoxy resin include polyamines obtained by reacting epichlorohydrin with a polyalkylene polyamine such as diethylenetriamine or triethylenetetraamine and a dicarboxylic acid such as adipic acid. Polyamine epoxy resin and the like obtained by the amine reaction. The commercially available products of this polyamide epoxy resin include "Sumirez Resin (registered trademark) 650" and "Sumirez Resin 675" (above manufactured by Sumika Chemtex Co., Ltd.), and "WS-525" (PMC in Japan) Co., Ltd.) and so on. In the case of blending an epoxy resin, the added amount is usually 1 to 100 parts by mass, and preferably 1 to 50 parts by mass based on 100 parts by mass of the polyvinyl alcohol resin.

The thickness of the adhesive layer formed of the dry-curing type adhesive is usually 0.001 to 5 μm, preferably 0.01 to 2 μm, and further preferably 0.01 to 0.5 μm. If the adhesive layer formed from the dry-curing adhesive is too thick, the optically anisotropic layer tends to have poor appearance.

The active energy ray-curable adhesive may include a solvent. The so-called active energy ray hardening type adhesive is an adhesive that is hardened by 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; and a radical polymerizable adhesive containing an acrylic curing component and a radical polymerization initiator. Contains both a cationically polymerizable hardening component such as an epoxy compound and a radically polymerizable hardening component such as an acrylic compound, and further contains a cationic polymerization initiator and a radical polymerization initiator adhesive; and does not contain the same Such as a polymerization initiator, an adhesive that is hardened by irradiation with an electron beam, and the like.

Among these, a radically polymerizable active energy ray hardening type adhesive containing an acrylic hardening component and a radical polymerization initiator, and a cationic polymerizable active energy ray hardening containing an epoxy compound and a cationic polymerization initiator are preferred. Type adhesive. 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 the compound other than the epoxy compound include an oxetane compound and an acrylic compound.
Examples of the radical polymerization initiator include the photopolymerization initiators described above. Examples of commercially available cationic polymerization initiators include: "Kayarad" (registered trademark) series (manufactured by Nippon Kayaku Co., Ltd.), "Cyracure UVI" series (manufactured by Dow Chemical), and "CPI" series (San -Made by Apro Co., Ltd.), "TAZ", "BBI" and "DTS" (Made by Midori Kagaku Co., Ltd.), "Adeka Optomer" series (Made by ADEKA Co., Ltd.), "RHODORSIL" (registered trademark) (Manufactured by Rhodia Co., Ltd.). The content of the radical polymerization initiator and the cationic polymerization initiator is usually 0.5 to 20 parts by mass, and preferably 1 to 15 parts by mass with respect to 100 parts by mass of the active energy ray-curable adhesive.

The active energy ray-curable adhesive may further contain an ion trapping agent, an antioxidant, a chain transfer agent, an adhesion-imparting agent, a thermoplastic resin, a filler, a flow modifier, a plasticizer, and an antifoaming agent.

In this specification, an active energy ray is defined as an energy ray that can decompose a compound that generates an active species to generate an active species. Examples of such active energy rays include visible light, ultraviolet rays, infrared rays, X-rays, alpha rays, beta rays, gamma rays, and electron beams, and ultraviolet rays and electron beams are preferred. The preferable ultraviolet irradiation conditions are the same as the polymerization of the polymerizable liquid crystal compound.
[Example]

Hereinafter, the present invention will be described in more detail through examples. "%" And "part" in the examples are mass% and mass part unless otherwise noted.
The devices, measurement methods, and evaluation methods used in the examples are as follows.

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

[Determination of viscosity]
In Examples and Comparative Examples, the viscosity V and the viscosity of the solvent used at the time when 48 hours have elapsed after the mixing of all the components contained in the polymerizable liquid crystal composition are made using the vibration viscosity of CBC Materials Co., Ltd. The meter VM-10A-L was measured in accordance with "JIS 8803Z: 2011 Liquid Viscosity Measurement Method".

[Measurement of the maximum absorption wavelength λ _max (LC)]
The maximum absorption wavelengths of the polymerizable liquid crystal compounds (A) and (B), the photopolymerization initiator, and the liquid crystal cured film are determined by using an ultraviolet-visible spectrophotometer in chloroform ("UV-2450" manufactured by Shimadzu Corporation) And the determination.

[Measurement of polymerization rate]
The liquid crystal hardened films obtained in the examples and comparative examples were subjected to measurement of infrared total reflection absorption spectrum ("Model 670-IR" manufactured by Agilent Corporation) (incident angle 45 °). The peak intensity I (1) of the in-plane bending vibration (1408 cm ^-1 ) of the saturated bond and the peak intensity I (2) of the stretching vibration (1504 cm ^-1 ) of the unsaturated bond derived from the aromatic ring are calculated. '(P value of the surface perpendicular to the thickness direction of the liquid crystal cured film on the surface irradiated with ultraviolet rays).
Further, a solution obtained by dissolving the polymerizable liquid crystal compound (A) in chloroform was added dropwise to the germanium crystal and dried to obtain a thin layer of the polymerizable liquid crystal compound (A). The obtained thin layer was subjected to measurement of infrared total reflection absorption spectrum, and P0 (P value of the polymerizable liquid crystal compound (A)) was calculated from the obtained measurement result.
The polymerization rate defined by (1-P '/ P0) × 100 was calculated from the values of P' and P0. The larger the value, the higher the degree of hardening of the liquid crystal cured film.

[Evaluation of alignment]
The polarizing microscope (BX51, manufactured by Olympus Co., Ltd.) was used to observe the liquid crystal cured films obtained in the examples and comparative examples at a magnification of 400 times. Those with good alignment were set to "○", and those with insufficient alignment such as poor alignment on the surface were set to "x".

[Evaluation of uneven film thickness]
A pair of linear polarizing elements is superimposed on a light table so as to be orthogonally polarized. The liquid crystal hardened films obtained in the examples and comparative examples were placed between the linearly polarizing elements set on a light-transmitting table as described above. At this time, the retardation axis of the liquid crystal cured film is set so as to be substantially 45 ° with respect to the absorption axis of the polarizing element when viewed from the thickness direction. Thereafter, observation was performed visually. Based on the uniformity of the observed image (uniformity of the phase difference), the entire surface is substantially uniform without unevenness being recognized as "○", and the identified unevenness as "×".

[Example 1]
<Preparation of a composition for forming a photo-alignment film>
5 parts of a photo-alignment material having the following structure and 95 parts of cyclopentanone (solvent) were mixed as components, and the obtained mixture was stirred at 80 ° C. for 1 hour, thereby obtaining a photo-alignment film-forming composition (1) .
Photo-alignment materials:
[Chemical 3]

<Preparation of polymerizable liquid crystal composition>
Polymerizable liquid crystal compound (A) of the following structure, dibutyl hydroxytoluene (polymerization inhibitor) (BHT; manufactured by Wako Pure Chemical Industries, Ltd.), polyacrylate compound (leveling agent) (BYK-361N; BYK-Chemie Corporation) Production) and the following photopolymerization initiators were mixed in accordance with the composition shown in Table 1. Next, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration of the polymerizable liquid crystal composition became 9%, and the polymerizable liquid crystal composition was obtained by stirring at 80 ° C for 1 hour ( 1).
After the stirring was completed, that is, after the mixing of all the components contained in the polymerizable liquid crystal composition was completed, the polymerizable liquid crystal composition (1) was stored in a closed container at 23 ° C. under a fluorescent lamp (40 W) for 48 hours. . The viscosity V at 23 ° C of the polymerizable liquid crystal composition at the elapse of 48 hours after the end of the mixing was 2.53 mPa · s. The viscosity of NMP at 23 ° C was 1.89 mPa · s.

Polymerizable liquid crystal compound (A):
[Chemical 4]

The polymerizable liquid crystal compound (A) is synthesized by a method described in Japanese Patent Laid-Open No. 2010-31223. The maximum absorption wavelength λ _max (LC) of the polymerizable liquid crystal compound (A) measured in chloroform was 350 nm.

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

The content of the polyacrylate compound (leveling agent) in the polymerizable liquid crystal composition is 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 amounts to 100 parts of the polymerizable liquid crystal compound (A).
-Oxime ester type carbazole compound (Yanjiagu Oxe-03 (manufactured by BASF Japan Co., Ltd.)): 7.5 parts with respect to 100 parts of the polymerizable liquid crystal compound (A). Moreover, the maximum absorption wavelengths of the initiator measured in chloroform were 305 nm and 350 nm.
2-dimethylamino-2-benzyl-1- (4-olinylphenyl) butane-1-one (Yanjiagu 369 (Irg369); manufactured by BASF Japan Co., Ltd.): Relative to polymerizability The liquid crystal compound (A) was 100 parts in 3 parts. Furthermore, the maximum absorption wavelength of the initiator measured in chloroform was 320 nm.

＜ Manufacture of liquid crystal cured film and retardation film ＞
Using a corona treatment device ("AGF-B10" manufactured by Kasuga Electric Co., Ltd.) on a cyclic olefin polymer (COP) film (Zeonor Film (registered trademark) manufactured by Japan Zeon Corporation) ", Film thickness is 23 μm). Next, the surface of the COP film (substrate) subjected to the corona treatment was coated with the composition (1) for forming a photo-alignment film using a bar coater, dried at 80 ° C for 1 minute, and then polarized UV irradiation The device ("SPOT CURE SP-7 with Polarization Element Unit" manufactured by Oxtail Electric Co., Ltd.) was used to perform polarized UV exposure at a cumulative light amount of 100 mJ / cm ² to obtain a light alignment film. The film thickness of the obtained photo-alignment film was 100 nm. The above-mentioned corona treatment is performed once using the above-mentioned corona treatment device under the conditions of an output of 0.3 kW and a processing speed of 3 m / min.
Next, using a bar coater, the polymerizable liquid crystal composition (1) after 48 hours from the completion of the mixing was applied to the photo-alignment film, dried at 120 ° C for 1 minute, and then a high-pressure mercury lamp (oxtail motor "Unicure VB-15201BY-A" manufactured by Co., Ltd.) is irradiated with ultraviolet rays from the coating surface side of the coating solution (in a nitrogen environment, the cumulative light amount at a wavelength of 313 nm is 500 mJ / cm ² ), thereby forming a liquid crystal. Hardened film. The thickness of the liquid crystal cured film was 2 μm. A phase difference film including the substrate, the photo-alignment film, and the liquid crystal cured film was obtained in the above manner. The retardation film had a film thickness of 25 μm. Moreover, 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 component concentration of the polymerizable liquid crystal composition was set to 13%.

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

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

[Example 5]
The polymerizable liquid crystal compound was LC242 (manufactured by BASF Japan Co., Ltd.), the solvent was propylene glycol monomethyl ether acetate (PGMEA), the solid content concentration was 13%, and the content of dibutylhydroxytoluene was A polymerizable liquid crystal composition (5), a liquid crystal cured film, and a retardation film were obtained in the same manner as in Example 1 except that the content was 2%. Moreover, 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 liquid crystal cured film, and a retardation film were obtained in the same manner as in Example 1 except that the polymerizable liquid crystal compound was a polymerizable liquid crystal compound (B) having the following structure. The polymerizable liquid crystal compound (B) is synthesized by a method described in Japanese Patent Laid-Open No. 2010-24438. The maximum absorption wavelength λ _max (LC) of the polymerizable liquid crystal compound (B) measured in chloroform was 330 nm.

Polymerizable liquid crystal compound (B):
[Chemical 5]

[Comparative Examples 1 to 3]
A polymerizable liquid crystal composition (8) to (10) were obtained in the same manner as in Example 1, except that the solid component concentration and the content of dibutylhydroxytoluene (polymerization inhibitor) were as described in Table 1. , Liquid crystal hardened film, and retardation film. The viscosity of the polymerizable liquid crystal composition (8) prepared in Comparative Example 1 at 23 ° C immediately after the mixing was 3.12 mPa · s.

[Comparative Examples 4, 5]
The polymerizable liquid crystal compound was LC242 (manufactured by BASF Japan Co., Ltd.), the solvent was propylene glycol monomethyl ether acetate (PGMEA), the solid content concentration was 13%, and dibutylhydroxytoluene (polymerized The content of the inhibitor) was set to Table 1 except that the polymerizable liquid crystal compositions (11) and (12) were obtained in the same manner as in Example 1. When the polymerizable liquid crystal compositions (11) and (12) were stored in an airtight container at 23 ° C for 48 hours under a fluorescent lamp (40 W), they all gelled, and viscosity measurement could not be performed, and liquid crystal could not be formed Hardened film and retardation film.

The solid content concentration c (mass fraction), the content of the polymerization inhibitor (mass%) of the polymerizable liquid crystal compositions obtained in the examples and comparative examples, and the viscosity V (mPa · s) at the time of 48 hours after mixing ), And cV are shown in Table 1. Moreover, the evaluation of the orientation and film thickness unevenness of the liquid crystal cured film obtained in the Example and the comparative example, and a polymerization rate are shown in Table 1.

[Table 1]

As shown in Table 1, it can be seen that the liquid crystal cured films obtained from the polymerizable liquid crystal compositions of Examples 1 to 7 had good evaluations of the alignment and film thickness unevenness. Therefore, even after long-term storage, the polymerizable liquid crystal composition also had It is possible to suppress the occurrence of alignment defects and uneven film thickness of the obtained liquid crystal cured film. Moreover, it turns out that the polymerization rate of the liquid-crystal hardened film of Examples 1-7 is all 72% or more, and it has sufficient hardening degree as a retardation film use. On the other hand, it can be seen that the liquid crystal cured films obtained from the polymerizable liquid crystal compositions of Comparative Examples 1 to 3 have poor evaluations of either the alignment property or the uneven film thickness. Therefore, the polymerizable liquid crystal compositions of Comparative Examples 1 to 3 The occurrence of alignment defects or uneven thickness of the obtained liquid crystal cured film cannot be suppressed. In addition, as described above, the liquid crystal cured film obtained from the polymerizable liquid crystal compositions of Comparative Examples 4 and 5 was unable to form a liquid crystal cured film and a retardation film due to gelation, and the viscosity at 48 hours after the end of mixing could not be measured. .

Claims (11)

A polymerizable liquid crystal composition containing a polymerizable liquid crystal compound, a polymerization initiator, and an organic solvent, and The following formula (1) 0.15 ≦ cV ≦ 0.65 (1) [In the formula, cV represents the solid content concentration c (mass fraction) of the polymerizable liquid crystal composition, and the polymerizable liquid crystal composition at the time when 48 hours have elapsed after all the components contained in the polymerizable liquid crystal composition have been mixed. Product of viscosity V (mPa · s) at 23 ℃]. The polymerizable liquid crystal composition according to claim 1, wherein the polymerizable liquid crystal compound is a liquid crystal compound having a photopolymerizable group. For example, the polymerizable liquid crystal composition of claim 1 or 2, wherein the maximum absorption wavelength of the polymerization initiator is 300 to 400 nm. The polymerizable liquid crystal composition according to any one of claims 1 to 3, wherein the maximum absorption wavelength of the polymerizable liquid crystal compound is 300 to 400 nm. The polymerizable liquid crystal composition according to any one of claims 1 to 4, further comprising 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 relative 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, which is obtained by curing the polymerizable liquid crystal composition according to any one of claims 1 to 7, and is formed by polymerizing the polymerizable liquid crystal compound in an aligned state. A retardation film comprising a liquid crystal hardened film as claimed in claim 8. An elliptical polarizer includes a retardation film and a polarizing film as claimed in claim 9. A display device includes an elliptical polarizer as claimed in claim 10.