JP7339014B2 - Polymerizable liquid crystal composition - Google Patents

Description

The present invention relates to a polymerizable liquid crystal composition, a polarizing film formed from the polymerizable liquid crystal composition, a method for producing the same, a polarizing film including the polarizing film, a polarizing plate, and a display device having the same.

BACKGROUND ART Conventionally, polarizing plates have been used in various image display panels such as liquid crystal display panels and organic electroluminescence (organic EL) display panels by bonding them to image display elements such as liquid crystal cells and organic EL display elements. As such a polarizing plate, triacetyl cellulose is attached to at least one surface of a polarizer in which a compound exhibiting dichroism, such as iodine or a dichroic dye, is adsorbed and oriented on a polyvinyl alcohol-based resin film via an adhesive layer. A polarizing plate having a structure in which protective layers such as films are laminated is known.

In recent years, there has been a continuous demand for thinner displays such as image display panels, and further reduction in thickness is also required for polarizing plates and polarizers, which are one of the components. In response to such demands, for example, thin host-guest polarizers composed of a polymerizable liquid crystal compound and a compound exhibiting dichroism have been proposed (Patent Documents 1 to 3).

Japanese Patent Publication No. 2007-510946 JP 2016-186075 A JP 2013-210624 A

However, host-guest polarizers as described in the above patent documents are generally produced by curing a composition containing a polymerizable liquid crystal compound, a dichroic dye, and a polymerization initiator. When irradiated with active energy rays such as ultraviolet rays in the process, the dichroic dye is easily denatured by active species generated from the polymerization initiator contained in the composition that forms the polarizer, and the polarizing performance is not necessarily sufficient. not satisfactory.

Accordingly, the present invention provides a polymerizable liquid crystal composition that is suitable for forming a polarizing film having excellent polarizing performance, in which the dichroic dye is hardly denatured when forming the polarizing film (polarizer). for the purpose.

The inventors of the present invention have completed the present invention as a result of intensive studies to solve the above problems. That is, the present invention provides the following preferred aspects.
[1] A polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound having at least one polymerizable group and exhibiting smectic liquid crystallinity, a dichroic dye, and a photopolymerization initiator, wherein the photopolymerization initiator is the formula (1) in relation to the polymerizable liquid crystal compound:
0°C ≤ T1-T2 ≤ 12.0°C (1)
[Wherein, T1 is the liquid crystal expressed at the lowest temperature when the phase transition temperature is measured while the polymerizable liquid crystal compound is heated to 130° C. in the atmosphere and then cooled to 23° C. at 5° C./min. Phase transition temperature, T2 is a mixture of 100 parts by mass of the polymerizable liquid crystal compound and 5 parts by mass of the photopolymerization initiator, after heating to 130 ° C. in the atmosphere 5 ° C./min. It is the phase transition temperature to the liquid crystal phase that is expressed on the lowest temperature side when measuring the phase transition temperature while cooling to 23 ° C.]
A polymerizable liquid crystal composition that satisfies
[2] The polymerizable liquid crystal composition according to [1] above, which further contains a solvent.
[3] The polymerizable liquid crystal composition according to [1] or [2] above, wherein the polymerizable group possessed by the polymerizable liquid crystal compound is an acryloyloxy group or a methacryloyloxy group.
[4] The polymerizable liquid crystal composition according to any one of [1] to [3], wherein the dichroic dye is an azo dye.
[5] The polymerizable liquid crystal composition according to any one of [1] to [4], wherein the photopolymerization initiator has a weight average molecular weight of 500 or more and 2000 or less.
[6] The polymerizable liquid crystal composition according to any one of [1] to [5], containing 1 to 10 parts by mass of a photopolymerization initiator with respect to 100 parts by mass of the polymerizable liquid crystal compound.
[7] A polarizing film, which is a cured product of the polymerizable liquid crystal composition according to any one of [1] to [6], and exhibits a Bragg peak in X-ray diffraction measurement.
[8] The polarizing film according to [7] above, which has a thickness of 0.1 to 5 μm.
[9] A polarizing film comprising the polarizing film according to [7] or [8] and a transparent film.
[10] A polarizing plate comprising the polarizing film of [7] or [8] or the polarizing film of [9] and a retardation film.
[11] Retardation film represented by formula (X):
100≦Re(550)≦180 (X)
[Wherein, Re (550) represents an in-plane retardation value at a wavelength of 550 nm]
and the angle formed by the slow axis of the retardation film and the absorption axis of the polarizing film is substantially 45°.
[12] Retardation film represented by formula (Y):
Re(450)/Re(550) < 1 (Y)
[Wherein, Re (450) and Re (550) represent in-plane retardation values at wavelengths of 450 nm and 550 nm, respectively]
The polarizing plate of the above [10] or [11], which satisfies:
[13] The polarizing plate according to any one of [10] to [12] above, wherein the retardation film is composed of a polymer in an aligned state of a polymerizable liquid crystal compound.
[14] A display comprising the polarizing film of [9] or the polarizing plate of any one of [10] to [13].
[15] forming a coating film of the polymerizable liquid crystal composition according to any one of [1] to [6];
removing solvent from the coating;
raising the temperature to a temperature at which the polymerizable liquid crystal compound undergoes a phase transition to a liquid phase or higher, and then lowering the temperature to cause the polymerizable liquid crystal compound to undergo a phase transition to a smectic phase;
A method for producing a polarizing film, comprising polymerizing a polymerizable liquid crystal compound while maintaining the smectic phase.

According to the present invention, it is possible to provide a polymerizable liquid crystal composition that is suitable for forming a polarizing film having excellent polarizing performance and which hardly causes modification of the dichroic dye when forming the polarizing film.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. The scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the gist of the present invention.

<Polymerizable liquid crystal composition>
The polymerizable liquid crystal composition of the present invention comprises a polymerizable liquid crystal compound having at least one polymerizable group and exhibiting smectic liquid crystallinity (hereinafter also referred to as "polymerizable liquid crystal compound (A)"). By using a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity, a polarizing film with a high degree of alignment order can be formed. The liquid crystal state exhibited by the polymerizable liquid crystal compound (A) is a smectic phase (smectic liquid crystal state), and from the viewpoint of realizing a higher degree of orientational order, it is more preferable to be a high-order smectic phase (high-order smectic liquid crystal state). preferable. Here, the higher order smectic phase includes smectic B phase, smectic D phase, smectic E phase, smectic F phase, smectic G phase, smectic H phase, smectic I phase, smectic J phase, smectic K phase and smectic L phase. Among these, smectic B phase, smectic F phase and smectic I phase are more preferable. Thermotropic liquid crystals or lyotropic liquid crystals may be used as liquid crystals, but thermotropic liquid crystals are preferred because they allow precise film thickness control. The polymerizable liquid crystal compound may be a monomer, or may be an oligomer or polymer in which polymerizable groups are polymerized.

The polymerizable liquid crystal compound (A) is a liquid crystal compound having at least one polymerizable group. Here, the term "polymerizable group" refers to a group that can participate in a polymerization reaction due to an active radical generated from a polymerization initiator, an acid, or the like. Examples of the polymerizable group possessed by the polymerizable liquid crystal compound (A) include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group, oxetanyl group and the like. Among them, a radical polymerizable group is preferred, an acryloyloxy group, a methacryloyloxy group, a vinyl group and a vinyloxy group are more preferred, and an acryloyloxy group and a methacryloyloxy group are preferred.

The polymerizable liquid crystal compound (A) is not particularly limited as long as it has at least one polymerizable group and exhibits smectic liquid crystallinity, and known polymerizable liquid crystal compounds can be used. Compounds represented by (A1) (hereinafter also referred to as “polymerizable liquid crystal compound (A1)”) can be mentioned.
U ¹ -V ¹ -W ¹ -(X ¹ -Y ¹ -) _n -X ² -W ² -V ² -U ² (A1)
[In the formula (A1),
X ¹ and X ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein the divalent aromatic group or divalent alicyclic hydrocarbon A hydrogen atom contained in the 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, an alkoxy group having 1 to 4 carbon atoms, a cyano group or a nitro group. A carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom. However, at least one of X ¹ and X ² is an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group.
Y ¹ is a single bond or a divalent linking group.
n is 1 to 3, and when n is 2 or more, multiple X ^1s may be the same or different. X ² may be the same as or different from any or all of a plurality of X ¹ 's. Moreover, when n is 2 or more, the plurality of Y ¹ may be the same or different. From the viewpoint of liquid crystallinity, n is preferably 2 or more.
^U1 represents a hydrogen atom or a polymerizable group.
^U2 represents a polymerizable group.
W ¹ and W ² are each independently a single bond or a divalent linking group.
V ¹ and V ² each independently represent an optionally substituted alkanediyl group having 1 to 20 carbon atoms, and —CH ₂ — constituting the alkanediyl group is —O—, -CO-, -S- or NH- may be substituted. ]

In the polymerizable liquid crystal compound (A1), X ¹ and X ² are each independently preferably a 1,4-phenylene group optionally having a substituent, or a 1,4-phenylene group optionally having a substituent, or cyclohexane-1,4-diyl group, and at least one of X ¹ and X ² is a 1,4-phenylene group optionally having a substituent, or a 1,4-phenylene group optionally having a substituent cyclohexane-1,4-diyl group, preferably trans-cyclohexane-1,4-diyl group. Optionally substituted 1,4-phenylene group or optionally substituted cyclohexane-1,4-diyl group may have a methyl group, ethyl and alkyl groups having 1 to 4 carbon atoms such as butyl group, cyano group and halogen atoms such as chlorine atom and fluorine atom. It is preferably unsubstituted.

The polymerizable liquid crystal compound (A1) has the formula (A1-1) in the formula (A1):
-(X ¹ -Y ¹ -) _n -X ² - (A1-1)
[In the formula, X ¹ , Y ¹ , X ² and n each have the same meaning as above. ]
[hereinafter referred to as partial structure (A1-1). ] has an asymmetrical structure, from the viewpoint of easily exhibiting smectic liquid crystallinity. Examples of the polymerizable liquid crystal compound (A1) having an asymmetric partial structure (A1-1) include:
a polymerizable liquid crystal compound (A1) in which n is 1 and one X ¹ and X ² have different structures;
A compound in which n is 2, two Y ^1s have the same structure, two X ^1s have the same structure, and one X ² has a different structure from the two X ^1s Polymerizable liquid crystal compound (A1);
^{The polymerizable liquid crystal compound ( A1} );
A polymerizable liquid crystal in which n is 3, three ^Y1s have the same structure, and one of the three ^X1s and one ^X2 has a different structure from all the other three Compound (A1);
is mentioned.

Y ¹ is -CH ₂ CH ₂ -, -CH ₂ O-, -CH ₂ CH ₂ O-, -COO-, -OCOO-, a single bond, -N=N-, -CR ^a =CR ^b -, -C≡C-, -CR ^a =N- or -CO-NR ^a - are preferred. R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y ¹ is more preferably —CH ₂ CH ₂ —, —COO—, or a single bond, and when there are multiple Y ^1s , Y ¹ bonded to X ² is —CH ₂ CH ₂ — or CH ₂ O— is more preferred. When X ¹ and X ² all have the same structure, it is preferred that there are two or more Y ¹ with different binding modes. When a plurality of ^Y1 's with different bonding methods exist, the structure is asymmetrical, and smectic liquid crystallinity tends to occur.

^U2 is a polymerizable group. U ¹ is a hydrogen atom or a polymerizable group, preferably a polymerizable group. Both U ¹ and U ² are preferably polymerizable groups, and preferably both are radically polymerizable groups. Examples of the polymerizable group include the same groups as those exemplified above as the polymerizable group possessed by the polymerizable liquid crystal compound (A). The polymerizable group represented by ^U1 and the polymerizable group represented by ^U2 may be different from each other, but are preferably of the same type. The polymerizable group may be in a polymerized state or in an unpolymerized state, preferably in an unpolymerized state.

Alkanediyl groups represented by V ¹ and V ² include methylene group, ethylene group, propane-1,3-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, pentane- 1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, decane-1,10-diyl group, tetradecane-1,14-diyl and icosane-1,20-diyl groups. V ¹ and V ² are preferably alkanediyl groups having 2 to 12 carbon atoms, more preferably alkanediyl groups having 6 to 12 carbon atoms.

Examples of the substituent optionally possessed by the alkanediyl group include a cyano group and a halogen atom. is more preferred.

W ¹ and W ² are each independently preferably a single bond, -O-, -S-, -COO- or -OCOO-, more preferably a single bond or -O-.

The polymerizable liquid crystal compound (A) is not particularly limited as long as it has at least one polymerizable group and exhibits smectic liquid crystallinity, and known polymerizable liquid crystal compounds can be used. As a structure that easily exhibits smectic liquid crystallinity, it is preferable to have an asymmetric molecular structure in the molecular structure. Specifically, a polymerizable liquid crystal compound having the following partial structures (Aa) to (Ai). and more preferably a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity. It is more preferable to have a partial structure of (Aa), (Ab) or (Ac) from the viewpoint of easily exhibiting high-order smectic liquid crystallinity. In (Aa) to (Ai) below, * represents a bond (single bond).

Examples of the polymerizable liquid crystal compound (A) include compounds represented by formulas (A-1) to (A-25). When the polymerizable liquid crystal compound (A) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably a trans form.

Among these, formula (A-2), formula (A-3), formula (A-4), formula (A-5), formula (A-6), formula (A-7), formula (A- 8), at least one selected from the group consisting of compounds represented by formula (A-13), formula (A-14), formula (A-15), formula (A-16) and formula (A-17) Seeds are preferred. As the polymerizable liquid crystal compound (A), one type may be used alone, or two or more types may be used in combination.

The polymerizable liquid crystal compound (A) is described in Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), or a known method described in Japanese Patent No. 4,719,156.

The polymerizable liquid crystal composition of the present invention may contain other polymerizable liquid crystal compounds other than the polymerizable liquid crystal compound (A) as long as the effects of the present invention are not impaired. From the standpoint of obtaining the , more preferably 90% by mass or more.

When the polymerizable liquid crystal composition of the present invention contains two or more polymerizable liquid crystal compounds (A), at least one of them may be the polymerizable liquid crystal compound (A1), all of which are polymerizable liquid crystal compounds. (A1) may be used. By combining a plurality of polymerizable liquid crystal compounds, it may be possible to temporarily maintain liquid crystallinity even at temperatures below the liquid crystal-crystal phase transition temperature.

The content of the polymerizable liquid crystal compound in the polymerizable liquid crystal composition of the present invention is preferably 40 to 99.9% by mass, more preferably 60 to 99% by mass, based on the solid content of the polymerizable liquid crystal composition. and more preferably 70 to 99% by mass. When the content of the polymerizable liquid crystal compound is within the above range, the orientation of the polymerizable liquid crystal compound tends to be high. In the present specification, the solid content refers to the total amount of components excluding the solvent from the polymerizable liquid crystal composition.

The polymerizable liquid crystal composition of the present invention contains a dichroic dye. Here, the term "dichroic dye" means a dye having different absorbance in the long-axis direction and the short-axis direction of the molecule. The dichroic dye that can be used in the present invention is not particularly limited as long as it has the above properties, and may be a dye or a pigment. Two or more dyes or pigments may be used in combination, or a dye and a pigment may be used in combination.

Dichroic dyes preferably have a maximum absorption wavelength (λ _MAX ) in the range of 300 to 700 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes and anthraquinone dyes.

Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakis azo dyes and stilbene azo dyes, and preferred are bisazo dyes and trisazo dyes. (I)”).
K ¹ (-N=N-K ² ) _p -N=N-K ³ (I)
[In formula (I), K ¹ and K ³ are each independently a phenyl group optionally having a substituent, a naphthyl group optionally having a substituent, or a represents a good monovalent heterocyclic group. K ² is a p-phenylene group optionally having substituents, a naphthalene-1,4-diyl group optionally having substituents or a divalent heterocyclic ring optionally having substituents represents a group. p represents an integer of 1 to 4; When p is an integer of 2 or more, multiple ^K2 may be the same or different. The -N=N- bond may be replaced with -C≡C-, -COO-, -NHCO-, or -N=CH- bond within the range of absorption in the visible region. ]

Examples of monovalent heterocyclic groups include groups obtained by removing one hydrogen atom from heterocyclic compounds such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole. The divalent heterocyclic group includes a group obtained by removing two hydrogen atoms from the above heterocyclic compound.

Optional substituents of the phenyl group, naphthyl group and monovalent heterocyclic group for K ¹ and K ³ and the p-phenylene group, naphthalene-1,4-diyl group and divalent heterocyclic group for K ² is an alkyl group having 1 to 4 carbon atoms; an alkoxy group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group and a butoxy group; a fluorinated alkyl group having 1 to 4 carbon atoms such as a trifluoromethyl group; a cyano group; Nitro group; halogen atom; substituted or unsubstituted amino group such as amino group, diethylamino group, pyrrolidino group (substituted amino group means amino group having one or two alkyl groups having 1 to 6 carbon atoms, or two It means an amino group in which substituted alkyl groups are bonded together to form an alkanediyl group having 2 to 8 carbon atoms, and an unsubstituted amino group is —NH ₂ .).

［式（Ｉ－１）～（Ｉ－８）中、
Ｂ^１～Ｂ^３０は、互いに独立して、水素原子、炭素数１～６のアルキル基、炭素数１～４のアルコキシ基、シアノ基、ニトロ基、置換または無置換のアミノ基（置換アミノ基および無置換アミノ基の定義は前記のとおり）、塩素原子またはトリフルオロメチル基を表わす。
ｎ１～ｎ４は、互いに独立に０～３の整数を表わす。
ｎ１が２以上である場合、複数のＢ^２は互いに同一でも異なっていてもよく、
ｎ２が２以上である場合、複数のＢ^６は互いに同一でも異なっていてもよく、
ｎ３が２以上である場合、複数のＢ^９は互いに同一でも異なっていてもよく、
ｎ４が２以上である場合、複数のＢ^１４は互いに同一でも異なっていてもよい。］ Among compounds (I), compounds represented by any one of the following formulas (I-1) to (I-6) are preferred.

[In the formulas (I-1) to (I-8),
B ¹ to B ³⁰ each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (substituted amino group and unsubstituted amino group are defined above), chlorine atom or trifluoromethyl group.
n1 to n4 each independently represents an integer of 0 to 3;
When n1 is 2 or more, the plurality of ^B2 may be the same or different,
When n2 is 2 or more, the plurality of ^B6 may be the same or different,
When n3 is 2 or more, multiple ^B9 may be the same or different,
When n4 is 2 or more, the plurality of ^B14 may be the same or different. ]

［式（Ｉ－９）中、
Ｒ^１～Ｒ^８は、互いに独立して、水素原子、－Ｒ^ｘ、－ＮＨ_２、－ＮＨＲ^ｘ、－ＮＲ^ｘ _２、－ＳＲ^ｘまたはハロゲン原子を表わす。
Ｒ^ｘは、炭素数１～４のアルキル基または炭素数６～１２のアリール基を表わす。］ As the anthraquinone dye, a compound represented by formula (I-9) is preferable.

[In the formula (I-9),
R ¹ to R ⁸ independently represent a hydrogen atom, —R ^x , —NH ₂ , —NHR ^x , —NR ^x ₂ , —SR ^x or a halogen atom.
R ^x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]

［式（Ｉ－１０）中、
Ｒ^９～Ｒ^１５は、互いに独立して、水素原子、－Ｒ^ｘ、－ＮＨ_２、－ＮＨＲ^ｘ、－ＮＲ^ｘ _２、－ＳＲ^ｘまたはハロゲン原子を表わす。
Ｒ^ｘは、炭素数１～４のアルキル基または炭素数６～１２のアリール基を表わす。］ As the oxazone dye, a compound represented by formula (I-10) is preferable.

[In the formula (I-10),
R ⁹ to R ¹⁵ each independently represent a hydrogen atom, —R ^x , —NH ₂ , —NHR ^x , —NR ^x ₂ , —SR ^x or a halogen atom.
R ^x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]

［式（Ｉ－１１）中、
Ｒ^１６～Ｒ^２３は、互いに独立して、水素原子、－Ｒ^ｘ、－ＮＨ_２、－ＮＨＲ^ｘ、－ＮＲ^ｘ _２、－ＳＲ^ｘまたはハロゲン原子を表わす。
Ｒ^ｘは、炭素数１～４のアルキル基または炭素数６～１２のアリール基を表わす。］
式（Ｉ－９）、式（Ｉ－１０）および式（Ｉ－１１）において、Ｒ^ｘの炭素数１～６のアルキル基としては、メチル基、エチル基、プロピル基、ブチル基、ペンチル基およびヘキシル基等が挙げられ、炭素数６～１２のアリール基としては、フェニル基、トルイル基、キシリル基およびナフチル基等が挙げられる。 As the acridine dye, a compound represented by formula (I-11) is preferable.

[In the formula (I-11),
R ¹⁶ to R ²³ each independently represent a hydrogen atom, —R ^x , —NH ₂ , —NHR ^x , —NR ^x ₂ , —SR ^x or a halogen atom.
R ^x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms. ]
In formula (I-9), formula (I-10) and formula (I-11), the alkyl group having 1 to 6 carbon atoms for R ^x includes a methyl group, an ethyl group, a propyl group, a butyl group and a pentyl group. and hexyl group, and the aryl group having 6 to 12 carbon atoms includes phenyl group, toluyl group, xylyl group, naphthyl group and the like.

［式（Ｉ－１２）中、
Ｄ^１およびＤ^２は、互いに独立に、式（Ｉ－１２ａ）～式（Ｉ－１２ｄ）のいずれかで表される基を表わす。

ｎ５は１～３の整数を表わす。］

［式（Ｉ－１３）中、
Ｄ^３およびＤ^４は、互いに独立に、式（Ｉ－１３ａ）～式（１－１３ｈ）のいずれかで表される基を表わす。

ｎ６は１～３の整数を表わす。］ As the cyanine dye, a compound represented by formula (I-12) and a compound represented by formula (I-13) are preferable.

[In the formula (I-12),
D ¹ and D ² each independently represent a group represented by any one of formulas (I-12a) to (I-12d).

n5 represents an integer of 1-3. ]

[In the formula (I-13),
D ³ and D ⁴ each independently represent a group represented by any one of formulas (I-13a) to (1-13h).

n6 represents an integer of 1-3. ]

The polymerizable liquid crystal composition of the present invention is excellent in the effect of suppressing photodegradation of the dichroic dye in the polarizing film when forming the polarizing film. When using a dichroic dye that tends to generate Therefore, the polymerizable liquid crystal composition of the present invention is particularly advantageous when using a dichroic dye that is susceptible to photodegradation. The dye is preferably an azo dye.

The content of the dichroic dye in the polymerizable liquid crystal composition of the present invention can be appropriately determined according to the type of the dichroic dye used, etc., but is preferably 0.00 to 100 parts by mass of the polymerizable liquid crystal compound. It is 1 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and still more preferably 0.1 to 12 parts by mass. When the content of the dichroic dye is within the above range, the alignment of the polymerizable liquid crystal compound is less likely to be disturbed, and a polarizing film having a high degree of alignment order can be obtained.

The polymerizable liquid crystal composition of the present invention contains a photopolymerization initiator. The photopolymerization initiator contained in the polymerizable liquid crystal composition of the present invention has the formula (1) in relation to the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition:
0°C ≤ T1-T2 ≤ 12.0°C (1)
It is a photopolymerization initiator that satisfies

In the formula (1), T1 is the temperature of the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition up to 130° C. in the atmosphere, and then the phase transition temperature while cooling to 23° C. at 5° C./min. It is the phase transition temperature to the liquid crystal phase that appears on the lowest temperature side when measured. In T2, a mixture consisting of 100 parts by mass of the polymerizable liquid crystal compound and 5 parts by mass of the photopolymerization initiator was heated to 130°C in the atmosphere and then cooled to 23°C at 5°C/min. It is the phase transition temperature to the liquid crystal phase that appears on the lowest temperature side when the transition temperature is measured. When the polymerizable liquid crystal composition of the present invention contains two or more polymerizable liquid crystal compounds, the above T1 and T2 are polymerizable liquid crystal compounds ( mixture). Detailed methods for measuring T1 and T2 are as described in the examples below.

In general, excellent polarizing performance can be obtained when a dichroic dye is included in a polymerizable liquid crystal compound and the polymerizable liquid crystal compound and the dichroic dye are oriented with a high degree of order. On the other hand, when a photopolymerization initiator is used to form the polarizing film, the photopolymerization initiator is aligned with the polymerizable liquid crystal compound and the dichroic dye, and when the polymerizable liquid crystal compound is polymerized, an active energy ray such as ultraviolet rays is generated. is irradiated, and active species are generated from the photopolymerization initiator. When the intermolecular distance between the photopolymerization initiator and the dichroic dye is short, the dichroic dye in the vicinity of the photopolymerization initiator is denatured by the active species, so that the polarizing performance of the obtained polarizing film is lowered. can cause problems.

Since the polymerizable liquid crystal composition of the present invention contains a photopolymerization initiator that satisfies the above formula (1), it can exhibit a high effect of suppressing deterioration of polarizing performance when a polarizing film is formed.
In formula (1), T1-T2 is an index representing the effect of the photopolymerization initiator on the phase transition temperature in the liquid crystal state. The larger the value of T1-T2, the more similar the molecular structure of the polymerizable liquid crystal compound and the photopolymerization initiator. It means that a relatively large amount of photoinitiator is present. In other words, the greater the value of T1-T2, the more likely the dichroic dye is denatured during the polymerization of the polymerizable liquid crystal compound. On the other hand, the smaller the value of T1-T2, the longer the intermolecular distance between the dichroic dye present in the polymerizable liquid crystal compound and the photopolymerization initiator, and the higher the photodegradation of the dichroic dye. It is presumed that a suppressing effect can be obtained and a polarizing film having excellent polarizing performance can be obtained.

In the photopolymerization initiator contained in the polymerizable liquid crystal composition of the present invention, the value of T1-T2 is 0° C. or higher and 12.0° C. or lower, preferably 0.5° C. or higher, more preferably 1° C. or higher. more preferably 2° C. or higher, still more preferably 3° C. or higher, and preferably 11.8° C. or lower. When the value of T1−T2 is 0.5° C. or more, the molecular structure of the polymerizable liquid crystal compound constituting the polymerizable liquid crystal composition and the molecular structure of the photopolymerization initiator do not differ greatly, so the photopolymerization initiator is used. It is easy to align with a polymerizable liquid crystal compound with a high degree of order, and the effect of suppressing photodegradation of the dichroic dye can be sufficiently exhibited. On the other hand, when the value of T1−T2 exceeds 12.0° C., the molecular structure of the polymerizable liquid crystal compound constituting the polymerizable liquid crystal composition and the molecular structure of the photopolymerization initiator tend to resemble each other, resulting in dichroism. The photopolymerization initiator tends to exist closer to the dye, and the dichroic dye tends to be denatured by the active species generated by the photopolymerization initiator. When the value of T1-T2 is within the above range, it becomes difficult for the photopolymerization initiator to exist in the vicinity of the dichroic dye enclosed in the polymerizable liquid crystal compound, and a high inhibitory effect on the modification of the dichroic dye is obtained. I can expect it.

If the photopolymerization initiator is a compound that satisfies the above formula (1) in relation to the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition and can initiate the polymerization reaction of the polymerizable liquid crystal compound, its type is particularly Not limited. Specifically, photopolymerization initiators capable of generating active radicals or acids by the action of light may be mentioned, and among these, photopolymerization initiators capable of generating radicals by the action of light are preferred. A photoinitiator can be used individually or in combination of 2 or more types.

Examples of photopolymerization initiators include photopolymerization initiators that generate active radicals. Examples of the photopolymerization initiator include a self-cleavage photopolymerization initiator and a hydrogen abstraction photopolymerization initiator.
Self-cleavage photopolymerization initiators include self-cleavage benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, and azo compounds. Available. In addition, as a hydrogen abstraction type photopolymerization initiator, hydrogen abstraction type benzophenone compounds, benzoin ether compounds, benzyl ketal compounds, dibenzosuberone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds. compounds, dialkoxyacetophenone-based compounds, halogenobisimidazole-based compounds, halogenotriazine-based compounds, triazine-based compounds, and the like can be used.

As photopolymerization initiators that generate acid, iodonium salts, sulfonium salts, and the like can be used.
From the viewpoint of reaction efficiency at low temperatures, self-cleavage photopolymerization initiators are preferred, and acetophenone-based compounds, hydroxyacetophenone-based compounds, α-aminoacetophenone-based compounds, and oxime ester-based compounds are particularly preferred.

Examples of photopolymerization initiators include the following.
Benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether;
2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethan-1-one, 2-hydroxy-2-methyl-1-[4-(2- Hydroxyacetophenones such as hydroxyethoxy)phenyl]propan-1-one, oligomers of 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one system compound;
α-Aminoacetophenones such as 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one system compound;
1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3 -Oxime ester compounds such as yl]-, 1-(O-acetyloxime);
Acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide;
benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4′-methyldiphenylsulfide, 3,3′,4,4′-tetra(tert-butylperoxycarbonyl)benzophenone and 2,4, Benzophenone compounds such as 6-trimethylbenzophenone;
Dialkoxyacetophenone compounds such as diethoxyacetophenone;
2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3, 5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(5 -methylfuran-2-yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3,5- Triazines, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine and 2,4-bis(trichloromethyl)-6- triazine compounds such as [2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine;
The photopolymerization initiator may be appropriately selected from, for example, the above photopolymerization initiators in relation to the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition.

A commercially available photopolymerization initiator may be used as the photopolymerization initiator. Commercially available photoinitiators include Irgacure® 907, 184, 651, 819, 250 and 369, 379, 127, 754, OXE01, OXE02, OXE03 (manufactured by BASF); Omnirad BCIM, Esacure 1001M, Esacure KIP160 (manufactured by IDM Resins B.V.); Seikuol® BZ, Z, and BEE (manufactured by Seiko Chemical Co., Ltd.); kayacure® BP100, and UVI-6992 ( Dow Chemical Co., Ltd.); Adeka Optomer SP-152, N-1717, N-1919, SP-170, Adeka Arkles NCI-831, Adeka Arkles NCI-930 (manufactured by ADEKA Co., Ltd.); TAZ-A , and TAZ-PP (manufactured by Nihon SiberHegner Co., Ltd.); and TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.);

The weight average molecular weight of the photopolymerization initiator is preferably 500 or more and 2000 or less, more preferably 600 or more, still more preferably 700 or more, more preferably 1500 or less, still more preferably 1000 or less. When the weight-average molecular weight of the photopolymerization initiator is at least the above lower limit, it becomes difficult to align with the polymerizable liquid crystal compound, and the dichroic dye contained in the polymerizable liquid crystal compound tends to be hardly modified. When the weight average molecular weight of the photopolymerization initiator is equal to or less than the above upper limit, it is possible to suppress the disturbance of the orientation of the polymerizable liquid crystal compound due to the photopolymerization initiator, and maintain a high degree of orientational order to achieve excellent polarization performance. It is possible to obtain a polarizing film having

A photopolymerization initiator having a large steric hindrance as a molecular structure and a low linearity tends to be difficult to align with the polymerizable liquid crystal compound and to hardly cause modification of the dichroic dye. Examples of photopolymerization initiators having such a molecular structure include the following compounds.

Among them, although not limited to these, the steric hindrance is large as a molecular structure, and the dichroic dye tends to be difficult to modify. It is preferable to have a partial structure that is From the viewpoint of the reaction mechanism of the photopolymerization initiator, oxime ester compounds and benzophenone compounds are preferable, and oxime ester compounds are more preferable.

式（Ｂ－１）中、「＊」は結合手（単結合）を表し、ベンゼン環における結合手の数は１～５であってよく、その位置も特に限定されるものではない。ＸはＮＲ１、ＳまたはＣ＝Ｏを表し、Ｒ１は炭素数１～４のアルキル基を表す。Ｙ１およびＹ２は水素原子、もしくはＹ１とＹ２の連結基を表す。

In formula (B-1), "*" represents a bond (single bond), the number of bonds in the benzene ring may be 1 to 5, and the positions thereof are not particularly limited. X represents NR1, S or C═O, and R1 represents an alkyl group having 1 to 4 carbon atoms. Y1 and Y2 represent a hydrogen atom or a linking group of Y1 and Y2.

The content of the photopolymerization initiator in the polymerizable liquid crystal composition of the present invention is preferably 1 to 10 parts by mass, more preferably 1 to 8 parts by mass, and still more preferably 100 parts by mass of the polymerizable liquid crystal compound. is 2 to 8 parts by weight, particularly preferably 4 to 8 parts by weight. When the content of the photopolymerization initiator is within the above range, the polymerization reaction of the polymerizable liquid crystal compound can be carried out without greatly disturbing the orientation of the polymerizable liquid crystal compound.

The polymerization rate of the polymerizable liquid crystal compound in the present invention is preferably 60% or more, more preferably 65% or more, and even more preferably 70% or more, from the viewpoint of line contamination and handling during production.

The polymerizable liquid crystal composition may further contain a photosensitizer. By using a photosensitizer, the polymerization reaction of the polymerizable liquid crystal compound can be further accelerated. Photosensitizers include xanthone, xanthone compounds such as thioxanthone (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone); anthracene compounds such as anthracene, alkoxy group-containing anthracene (e.g., dibutoxyanthracene); phenothiazine and and rubrene. A photosensitizer can be used individually or in combination of 2 or more types.

When the polymerizable liquid crystal composition of the present invention contains a photosensitizer, the content thereof may be appropriately determined according to the types and amounts of the photopolymerization initiator and the polymerizable liquid crystal compound. 0.1 to 30 parts by mass is preferable, 0.5 to 10 parts by mass is more preferable, and 0.5 to 8 parts by mass is even more preferable with respect to 100 parts by mass.

Moreover, 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 coating film obtained by applying the polymerizable liquid crystal composition more flat. mentioned. The leveling agent is preferably at least one selected from the group consisting of a leveling agent containing a polyacrylate compound as a main component and a leveling agent containing a fluorine atom-containing compound as a main component. A leveling agent can be used individually or in combination of 2 or more types.

Examples of leveling agents mainly composed of polyacrylate compounds include "BYK-350", "BYK-352", "BYK-353", "BYK-354", "BYK-355", and "BYK-358N". , “BYK-361N”, “BYK-380”, “BYK-381” and “BYK-392” (BYK Chemie).

Leveling agents mainly composed of fluorine atom-containing compounds include, for example, "Megafac (registered trademark) R-08", "R-30", "R-90", "F-410", "F-411", "F-443", "F-445", "F-470", "F-471", "F-477", "F-479", " F-482” and “F-483” (DIC Corporation); “Surflon (registered trademark) S-381”, “S-382”, “S-383”, “S-393”, "SC-101", "SC-105", "KH-40" and "SA-100" (AGC Seimi Chemical Co., Ltd.); "E1830", "E5844" (Daikin Fine Chemicals Laboratory Co., Ltd.) "Ftop EF301", "Ftop EF303", "Ftop EF351" and "Ftop EF352" (Mitsubishi Materials Electronic Chemicals Co., Ltd.).

When the polymerizable liquid crystal composition of the present invention contains a leveling agent, the content thereof is preferably 0.05 to 5 parts by mass, more preferably 0.05 to 3 parts by mass with respect to 100 parts by mass of the polymerizable liquid crystal compound. more preferred. When the content of the leveling agent is within the above range, the polymerizable liquid crystal compound tends to be horizontally aligned, unevenness is less likely to occur, and a smoother polarizing film tends to be obtained.

The polymerizable liquid crystal composition of the present invention may contain additives other than the photosensitizer and the leveling agent. Other additives include antioxidants, release agents, stabilizers, colorants such as bluing agents, flame retardants and lubricants. When the polymerizable liquid crystal composition contains other additives, the content of the other additives is preferably more than 0% and 20% by mass or less with respect to the solid content of the polymerizable liquid crystal composition. , and more preferably more than 0% and not more than 10% by mass.

The polymerizable liquid crystal composition of the invention may contain a solvent. Compounds exhibiting smectic liquid crystallinity generally have a high viscosity, so that the addition of a solvent to the polymerizable liquid crystal composition facilitates coating, and as a result, often facilitates the formation of a polarizing film. The solvent can be appropriately selected depending on the solubility of the polymerizable liquid crystal compound and the dichroic dye. Alcohol solvents such as ether, ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, ester solvents such as ethyl lactate, acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, methyl Ketone solvents such as 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, and chloroform, Examples include chlorinated hydrocarbon solvents such as chlorobenzene. These solvents can be used alone or in combination of two or more. The content of the solvent is preferably 100 to 1,900 parts by mass, more preferably 150 to 900 parts by mass, and still more preferably 180 to 600 parts by mass with respect to 100 parts by mass of the solid component constituting the polymerizable liquid crystal composition. part by mass.

The polymerizable liquid crystal composition of the present invention can be produced by a conventionally known method for preparing a polymerizable liquid crystal composition. It can be prepared by mixing and stirring the above additives, solvent, and the like.

<Polarizing film>
The polymerizable liquid crystal composition of the present invention has a structure in which the dichroic dye is unlikely to be denatured during curing by irradiation with active energy rays, so that a polarizing film having excellent polarizing performance can be obtained, which is suitable for the production of polarizing films. can be used for

A polarizing film with a high degree of orientational order provides a Bragg peak derived from a higher-order structure such as a hexatic phase or a crystal phase in X-ray diffraction measurement. A Bragg peak means a peak derived from a periodic plane structure of molecular orientation. Therefore, in the polarizing film formed from the polymerizable liquid crystal composition of the present invention, the polymerizable liquid crystal compound or its polymer is preferably oriented so that the polarizing film exhibits a Bragg peak in X-ray diffraction measurement. More preferably, it is a “horizontal alignment” in which the molecules of the polymerizable liquid crystal compound are aligned in the direction of light absorption. In the present invention, it is preferable to use a polarizing film in which the plane period interval of molecular orientation is 3.0 to 6.0 Å. A high degree of orientational order exhibiting a Bragg peak can be realized by controlling the type of polymerizable liquid crystal compound used, the type and amount of photopolymerization initiator, the type and amount of dichroic dye, and the like.

As described above, by using a photopolymerization initiator that satisfies the formula (1) in relation to the polymerizable liquid crystal compound, a dichroic dye is formed by active species generated from the photopolymerization initiator during polymerization of the polymerizable liquid crystal compound. Modification can be suppressed, and a polarizing film having excellent polarizing performance can be obtained while maintaining a high degree of alignment order of the polymerizable liquid crystal compound. Therefore, the present invention also covers a polarizing film which is a cured product of the polymerizable liquid crystal composition of the present invention and exhibits a Bragg peak in X-ray diffraction measurement.

The polarizing film of the present invention is formed by forming a coating film of the polymerizable liquid crystal composition of the present invention,
removing solvent from the coating;
raising the temperature to a temperature at which the polymerizable liquid crystal compound undergoes a phase transition to a liquid phase or higher, and then lowering the temperature to cause the polymerizable liquid crystal compound to undergo a phase transition to a smectic phase (smectic liquid crystal state);
It can be produced by a method including polymerizing a polymerizable liquid crystal compound while maintaining the smectic phase (smectic liquid crystal state).

Formation of the coating film of the polymerizable liquid crystal composition is performed, for example, by adding a polymerizable liquid crystal composition, in particular, a solvent to adjust the viscosity of the polymerizable liquid crystal composition (hereinafter, " (also referred to as "composition for forming a polarizing film"). Alternatively, the composition for forming a polarizing film may be directly applied onto the retardation film or other layers that constitute the polarizing plate of the present invention.

The substrate is typically a transparent substrate. When the base material is not placed on the display surface of the display element, for example, when a laminate obtained by removing the base material from the polarizing film is placed on the display surface of the display element, the base material does not have to be transparent. A transparent base material means a base material having transparency capable of transmitting light, particularly visible light, and transparency means a characteristic of having a transmittance of 80% or more for light rays having a wavelength of 380 to 780 nm. say. A translucent resin base material is mentioned as a specific transparent base material. Examples of the resin constituting the translucent resin base material include polyolefins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene-based polymers; polyvinyl alcohol; polyethylene terephthalate; cellulose esters such as diacetyl cellulose and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; From the viewpoint of availability and transparency, polyethylene terephthalate, polymethacrylate, cellulose ester, cyclic olefin resin, or polycarbonate are preferred. Cellulose ester is obtained by esterifying some or all of the hydroxyl groups contained in cellulose, and can be easily obtained from the market. Cellulose ester base materials are also readily available on the market. Commercially available cellulose ester substrates include, for example, "Fujitac Film" (Fuji Photo Film Co., Ltd.); "KC8UX2M", "KC8UY" and "KC4UY" (Konica Minolta Opto Co., Ltd.).

The properties required for the base material vary depending on the structure of the polarizing film, but generally, a base material with as little retardation as possible is preferred. Examples of the substrate having the smallest possible retardation include cellulose ester films having no retardation, such as Zero Tack (Konica Minolta Opto Co., Ltd.) and Z Tack (Fuji Film Co., Ltd.). An unstretched cyclic olefin resin substrate is also preferred. The surface of the substrate on which the polarizing film is not laminated may be subjected to hard coat treatment, antireflection treatment, antistatic treatment, or the like.

If the thickness of the substrate is too thin, the strength tends to be low and the workability tends to be poor.

Examples of methods for applying the polarizing film-forming composition to a substrate or the like include coating methods such as spin coating, extrusion, gravure coating, die coating, bar coating, and applicator methods, and printing such as flexography. well-known methods such as the method.

Next, the solvent is removed by drying or the like under conditions in which the polymerizable liquid crystal compound contained in the coating film obtained from the composition for forming a polarizing film is not polymerized, thereby forming a dry coating film. Drying methods include natural drying, ventilation drying, heat drying, and reduced pressure drying.

Furthermore, in order to cause the phase transition of the polymerizable liquid crystal compound to the liquid phase, the temperature is raised to a temperature higher than the temperature at which the polymerizable liquid crystal compound undergoes phase transition to the liquid phase, and then the temperature is lowered to convert the polymerizable liquid crystal compound into a smectic phase (smectic liquid crystal state). Phase transition. Such a phase transition may be carried out after removing the solvent in the coating film, or may be carried out simultaneously with the removal of the solvent.

By polymerizing the polymerizable liquid crystal compound while maintaining the smectic liquid crystal state of the polymerizable liquid crystal compound, a polarizing film is formed as a cured layer of the polymerizable liquid crystal composition. A photopolymerization method is preferable as the polymerization method. In photopolymerization, the light irradiated to the dry coating film includes the type of photopolymerization initiator contained in the dry coating film, the type of polymerizable liquid crystal compound (especially the type of polymerizable group possessed by the polymerizable liquid crystal compound). and is appropriately selected according to its amount. Specific examples thereof include at least one kind of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays and γ-rays, and active electron beams. Among them, ultraviolet light is preferable in that it is easy to control the progress of the polymerization reaction and that a widely used photopolymerization apparatus in the field can be used. It is preferable to select the types of the polymerizable liquid crystal compound and the photopolymerization initiator contained in the polymerizable liquid crystal composition. The polymerization temperature can also be controlled by irradiating light while cooling the dry coating film with an appropriate cooling means during polymerization. By adopting such a cooling means and polymerizing the polymerizable liquid crystal compound at a lower temperature, a polarizing film can be appropriately formed even if a base material having relatively low heat resistance is used. A patterned polarizing film can also be obtained by masking or developing during photopolymerization.

As the light source of the active energy ray, low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, xenon lamp, halogen lamp, carbon arc lamp, tungsten lamp, gallium lamp, excimer laser, wavelength range 380 ~ LED light sources that emit light at 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, and the like can be used.

The UV irradiation intensity is usually 10 to 3,000 mW/cm ² . The ultraviolet irradiation intensity is preferably in the wavelength range effective for activation of the photopolymerization initiator. The light irradiation time is usually 0.1 second to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, still more preferably 10 seconds to 1 minute. When irradiated once or multiple times with such an irradiation intensity of ultraviolet rays, the cumulative amount of light is 10 to 3,000 mJ/cm ² , preferably 50 to 2,000 mJ/cm ² , more preferably 100 to 1,000 mJ/cm. ² .

By performing photopolymerization, the polymerizable liquid crystal compound is polymerized while maintaining the liquid crystal state of a smectic phase, preferably a higher-order smectic phase, to form a polarizing film. A polarizing film obtained by polymerizing a polymerizable liquid crystal compound while maintaining the liquid crystal state of the smectic phase is different from the conventional host-guest type polarizing film, that is, the liquid crystal state of the nematic phase, due to the action of the dichroic dye. There is an advantage that the polarizing performance is high as compared with other polarizing films. In addition, it has the advantage of being superior in strength compared to those coated with only dichroic dyes or lyotropic liquid crystals.

The thickness of the polarizing film can be appropriately selected according to the display device to which it is applied. 3 μm or less. If the film thickness is thinner than this range, the required light absorption may not be obtained, and if the film thickness is thicker than this range, the alignment control force of the alignment film is reduced, and alignment defects tend to occur. It is in.

The polarizing film is preferably formed on the alignment film. The alignment film has an alignment regulating force that aligns the polymerizable liquid crystal compound in a desired direction. The alignment film has a solvent resistance that does not dissolve when a composition containing a polymerizable liquid crystal compound is applied, etc., and also has heat resistance in heat treatment for removing the solvent and for aligning the polymerizable liquid crystal compound. preferable. Examples of such an alignment film include an alignment film containing an alignment polymer, a photo-alignment film, a groove alignment film having an uneven pattern or a plurality of grooves on the surface, a stretched film stretched in the alignment direction, etc., and the accuracy of the alignment angle is improved. And from the viewpoint of quality, a photo-alignment film is preferable.

Examples of oriented polymers include polyamides and gelatins having amide bonds in the molecule, polyimides having imide bonds in the molecule and their hydrolysates such as polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, Polyethylenimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylate compounds are included. Among them, polyvinyl alcohol is preferred. Orientation polymer can be used individually or in combination of 2 or more types.

An oriented film containing an oriented polymer is usually produced by applying a composition in which an oriented polymer is dissolved in a solvent (hereinafter sometimes referred to as an "oriented polymer composition") to a substrate and removing the solvent, or It can be obtained by applying an oriented polymer composition to a substrate, removing the solvent, and rubbing (rubbing method). Examples of the solvent include the same solvents as those previously exemplified as solvents that can be used in forming the polarizing film.

The concentration of the oriented polymer in the oriented polymer composition may be within a range in which the oriented polymer material can be completely dissolved in the solvent. 0.1 to 10% is more preferable.

A commercially available alignment film material may be used as it is as the alignment polymer composition. Commercially available alignment film materials include Sanever (registered trademark, manufactured by Nissan Chemical Industries, Ltd.) and Optomer (registered trademark, manufactured by JSR Corporation).

Examples of the method for applying the oriented polymer composition to the substrate include the same methods as those exemplified as the method for applying the composition for forming a polarizing film to the substrate.

Methods for removing the solvent contained in the oriented polymer composition include natural drying, ventilation drying, heat drying, and vacuum drying.

In order to impart an alignment regulating force to the alignment film, a rubbing treatment can be performed as necessary (rubbing method).

As a method for imparting an alignment regulating force by a rubbing method, a rubbing cloth is wound around a rotating rubbing roll, and an orienting polymer composition is applied to the substrate and then annealed to form an orientation polymer composition on the substrate surface. A method of contacting films of oriented polymers is included.

A photo-alignment film is usually formed by applying a composition containing a polymer or monomer having a photoreactive group and a solvent (hereinafter also referred to as a "composition for forming a photo-alignment film") to a substrate, and polarized light (preferably, obtained by irradiating with polarized UV). The photo-alignment film is more preferable in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

A photoreactive group refers to a group that exhibits liquid crystal alignment ability upon irradiation with light. Specific examples include groups involved in photoreactions that cause liquid crystal alignment ability, such as orientation induction of molecules caused by light irradiation, isomerization reactions, dimerization reactions, photocrosslinking reactions, photodecomposition reactions, and the like. Among them, a group involved in a dimerization reaction or a photocrosslinking reaction is preferable from the viewpoint of excellent orientation. As the photoreactive group, a group having an unsaturated bond, particularly a double bond is preferable, and a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond Groups having at least one selected from the group consisting of a heavy bond (N=N bond) and a carbon-oxygen double bond (C=O bond) are particularly preferred.

Photoreactive groups having a C═C bond include vinyl groups, polyene groups, stilbene groups, stilbazole groups, stilbazolium groups, chalcone groups and cinnamoyl groups. Photoreactive groups having a C═N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. The photoreactive group having an N=N bond includes an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and a group having an azoxybenzene structure. Photoreactive groups having a C=O bond include benzophenone, coumarin, anthraquinone and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups.

Among them, a photoreactive group that participates in a photodimerization reaction is preferable, the amount of polarized light irradiation required for photoalignment is relatively small, and a photoalignment film having excellent thermal stability and stability over time can be easily obtained. Cinnamoyl and chalcone groups are preferred. As the polymer having a photoreactive group, a polymer having a cinnamoyl group having a cinnamic acid structure at the end of the polymer side chain is particularly preferred.

A photo-alignment inducing layer can be formed on a substrate by applying the composition for forming a photo-alignment film onto the substrate. Examples of the solvent contained in the composition include the same solvents as those previously exemplified as the solvent that can be used in forming the polarizing film, and are appropriately selected according to the solubility of the polymer or monomer having a photoreactive group. can be selected.

The content of the polymer or monomer having a photoreactive group in the composition for forming a photo-alignment film can be appropriately adjusted depending on the type of polymer or monomer and the thickness of the desired photo-alignment film. It is preferably at least 0.2% by mass, more preferably in the range of 0.3 to 10% by mass. The composition for forming a photo-alignment film may contain a polymer material such as polyvinyl alcohol or polyimide, or a photosensitizer, as long as the properties of the photo-alignment film are not significantly impaired.

The method for applying the photo-alignment film-forming composition to the substrate includes the same method as the method for applying the orienting polymer composition to the substrate. Examples of the method for removing the solvent from the coated composition for forming a photo-alignment film include a natural drying method, a ventilation drying method, a heating drying method, a reduced pressure drying method, and the like.

In order to irradiate polarized light, the composition for forming a photo-alignment film coated on the substrate, from which the solvent has been removed, is directly irradiated with polarized UV light. A format in which the light is irradiated may also be used. Moreover, it is particularly preferable that the polarized light is substantially parallel light. The wavelength of the polarized light to be irradiated is preferably in a wavelength range in which the photoreactive group of the polymer or monomer having a photoreactive group can absorb the light energy. Specifically, UV (ultraviolet rays) with a wavelength in the range of 250 to 400 nm is particularly preferred. Examples of the light source used for the polarized irradiation include a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, and an ultraviolet light laser such as KrF or ArF. preferable. Among these, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are preferable because of their high emission intensity of ultraviolet rays having a wavelength of 313 nm. Polarized UV can be emitted by passing the light from the light source through a suitable polarizer. As such a polarizer, a polarizing filter, a polarizing prism such as Glan-Thompson or Glan-Taylor, or a wire grid type polarizer can be used.

A plurality of regions (patterns) having different liquid crystal orientation directions can be formed by masking during rubbing or polarized light irradiation.

A groove alignment film is a film having an uneven pattern or a plurality of grooves on its surface. When a polymerizable liquid crystal compound is applied to a film having a plurality of linear grooves arranged at regular intervals, liquid crystal molecules are aligned along the grooves.

As a method for obtaining a grooved alignment film, after exposure through an exposure mask having patterned slits on the surface of a photosensitive polyimide film, development and rinsing are performed to form an uneven pattern, and a plate having grooves on the surface. A method of forming a layer of UV curable resin before curing on a shaped master, transferring the formed resin layer to a substrate and then curing, and a UV curable resin film before curing formed on the substrate, A method of pressing a roll-shaped master plate having a plurality of grooves to form unevenness and then curing the same may be used.

The thickness of the alignment film (orientation film or photo-alignment film containing an alignment polymer) is usually in the range of 10 to 10000 nm, preferably in the range of 10 to 1000 nm, more preferably 500 nm or less, still more preferably 10 ~200 nm, particularly preferably 50-150 nm.

<Polarizing film>
The present invention includes a polarizing film comprising the polarizing film of the present invention and a transparent film. As the transparent film that constitutes the polarizing film of the present invention, a long roll film is preferable because it can be continuously produced. Examples of resins constituting the film substrate include polyolefins such as polyethylene, polypropylene, and norbornene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyethylene terephthalate; and cellulose esters such as cellulose acetate propionate; polyethylene naphthalates; polycarbonates; polysulfones; polyethersulfones; polyetherketones;

In addition, commercially available cellulose ester base materials such as "Fujitac Film" (manufactured by Fuji Photo Film Co., Ltd.); . Commercially available cyclic olefin resins include "Topas" (registered trademark) (manufactured by Ticona (Germany)), "Arton" (registered trademark) (manufactured by JSR Corporation), "ZEONOR" (registered trademark), "ZEONEX" (registered trademark) (manufactured by Nippon Zeon Co., Ltd.) and "APEL" (registered trademark) (manufactured by Mitsui Chemicals, Inc.). Such a cyclic olefin resin can be used as a substrate by forming a film by a known method such as a solvent casting method or a melt extrusion method. A commercially available cyclic olefin resin base material can also be used. Examples of commercially available cyclic olefin resin substrates include "Escina" (registered trademark), "SCA40" (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), and "Zeonor Film" (registered trademark) (manufactured by Optes Co., Ltd.). ) and “Arton Film” (registered trademark) (manufactured by JSR Corporation).

In the polarizing film of the present invention, the transparent film may be laminated on only one side of the polarizing film, or may be laminated on both sides. When the polarizing film of the present invention includes a plurality of transparent films, they may be the same or different. Moreover, the polarizing film and the transparent film may be in contact with each other or may be separated from each other. Generally, the transparent film can be attached to the polarizing film via an adhesive layer or pressure-sensitive adhesive layer.

The thickness of the transparent film constituting the polarizing film of the present invention is preferably as thin as possible from the viewpoint of practical handling. The thickness of the substrate is usually 5 μm to 300 μm, preferably 20 μm to 200 μm, more preferably 20 to 100 μm.

<Polarizing plate>
The present invention includes a polarizing plate (elliptically polarizing plate) comprising the polarizing film of the present invention or the polarizing film of the present invention and a retardation film. In the polarizing plate of the present invention, the retardation film has the formula (X):
100≦Re(550)≦180 (X)
[Wherein, Re (550) represents an in-plane retardation value at a wavelength of 550 nm]
is preferably satisfied. When the retardation film has the in-plane retardation value represented by (X) above, it functions as a so-called λ/4 plate. The formula (X) preferably satisfies 100 nm≦Re(550)≦180 nm, more preferably 120 nm≦Re(550)≦160 nm.

In the polarizing plate of the present invention, the angle between the slow axis of the retardation film and the absorption axis of the polarizing film is preferably substantially 45°. In the present invention, "substantially 45°" means 45°±5°.

Furthermore, the retardation film has the formula (Y):
Re(450)/Re(550) < 1 (Y)
[Wherein, Re (450) and Re (550) represent in-plane retardation values at wavelengths of 450 nm and 550 nm, respectively]
is preferably satisfied. A retardation film satisfying the above formula (Y) has so-called reverse wavelength dispersion and exhibits excellent polarizing performance. The value of Re(450)/Re(550) is preferably 0.93 or less, more preferably 0.88 or less, still more preferably 0.86 or less, preferably 0.80 or more, more preferably 0.86 or less. 82 or more.

The retardation film may be a stretched film that imparts retardation by stretching a polymer, but from the viewpoint of thinning the polarizing plate, a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound (hereinafter referred to as " It is preferably a cured product of the polymerizable liquid crystal composition (B), which is composed of the polymer in the aligned state of the polymerizable liquid crystal compound. A polymerizable liquid crystal compound forming a retardation film (hereinafter also referred to as “polymerizable liquid crystal compound (B)”) means a liquid crystal compound having a polymerizable functional group, particularly a photopolymerizable functional group. A photopolymerizable functional group is a group that can participate in a polymerization reaction by an active radical generated from a photopolymerization initiator, an acid, or the like. Photopolymerizable functional groups include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxiranyl group and oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group and an oxetanyl group are preferred, and an acryloyloxy group is more preferred. Liquid crystallinity may be thermotropic liquid crystal or lyotropic liquid crystal, and phase order structure may be nematic liquid crystal or smectic liquid crystal. As the polymerizable liquid crystal compound, only one type may be used, or two or more types may be used in combination.

Examples of the polymerizable liquid crystal compound (B) include compounds that satisfy all of the following (a) to (d) from the viewpoint of facilitating film formation and imparting the retardation property represented by the formula (Y). .

(A) a compound having thermotropic liquid crystallinity;
(a) The polymerizable liquid crystal compound has π electrons along the longitudinal direction (a).
(c) It has π electrons in the direction crossing the major axis direction (a) [intersecting direction (b)].
(d) of the polymerizable liquid crystal compound defined by the formula (i), where N (πa) is the total number of π electrons present in the longitudinal direction (a), and N (Aa) is the total molecular weight present in the longitudinal direction; π electron density in the longitudinal direction (a):
D(πa)=N(πa)/N(Aa) (i)
And, the sum of the π electrons present in the cross direction (b) is N (πb), and the sum of the molecular weights present in the cross direction (b) is N (Ab) of the polymerizable liquid crystal compound defined by the formula (ii) π electron density in cross direction (b):
D(πb)=N(πb)/N(Ab) (ii)
and
0≦[D(πa)/D(πb)]≦1
[that is, the π electron density in the cross direction (b) is higher than the π electron density in the long axis direction (a)].
The polymerizable liquid crystal compound (B) that satisfies all of the above (a) to (d) is coated on an alignment film formed by rubbing and heated to a phase transition temperature or higher to form a nematic phase. is possible. In the nematic phase formed by aligning the polymerizable liquid crystal compound (B), the long axis directions of the polymerizable liquid crystal compound are usually oriented parallel to each other, and the long axis direction is the alignment direction of the nematic phase. becomes.

で表される化合物が挙げられる。前記式（ＩＩ）で表される化合物は単独または２種以上組み合わせて使用できる。 The polymerizable liquid crystal compound (B) having the above properties generally exhibits reverse wavelength dispersion in many cases. As a compound satisfying the above characteristics (a) to (d), for example, formula (II):

The compound represented by is mentioned. The compounds represented by formula (II) can be used singly or in combination of two or more.

In formula (II), Ar represents an optionally substituted divalent aromatic group. The aromatic group referred to herein is a group having a planar cyclic structure, and the number of π electrons of the cyclic 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 heteroatoms such as -N= and -S-, the non-covalently bonded electron pairs on these heteroatoms satisfy Hückel's rule and have aromaticity. At least one or more of a nitrogen atom, an oxygen atom and a sulfur atom are preferably contained in the divalent aromatic group.

G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group is a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, a carbon may be substituted with an alkoxy group, cyano group or nitro group having a number of 1 to 4, and the carbon atoms constituting the divalent aromatic group or divalent alicyclic hydrocarbon group are an oxygen atom or a sulfur atom; Alternatively, it may be substituted with a nitrogen atom.

L ¹ , L ² , B ¹ and B ² are each independently a single bond or a divalent linking group.

k and l each independently represents an integer of 0 to 3 and satisfies the relationship 1≦k+l. Here, when 2≦k+l, B ¹ and B ² and G ¹ and G ² may be the same or different from each other.

E ¹ and E ² each independently represent an alkanediyl group having 1 to 17 carbon atoms, wherein the hydrogen atoms contained in the alkanediyl group may be substituted with a halogen atom, and the alkanediyl group —CH ₂ — included may be substituted with —O—, —S—, or —Si—. P ¹ and P ² independently represent a polymerizable group or a hydrogen atom, at least one of which is a polymerizable group.

G ¹ and G ² are each independently preferably a 1,4-phenylenediyl group optionally substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms. , a 1,4-cyclohexanediyl group optionally substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably 1 substituted with a methyl group ,4-phenylenediyl group, unsubstituted 1,4-phenylenediyl group or unsubstituted 1,4-trans-cyclohexanediyl group, particularly preferably unsubstituted 1,4-phenylenediyl group or unsubstituted It is a substituted 1,4-trans-cyclohexanediyl group. At least one of G ¹ and G ² present in plurality is preferably a divalent alicyclic hydrocarbon group, and at least one of G ¹ and G ² bonded to L ¹ or L ² is more preferably 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 having 1 to 4 carbon atoms or a hydrogen atom. L ¹ and L ² are each independently more preferably a single bond, -OR ^a2-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a4-1 -, or OCOR ^a6-1 - . Here, R ^a2-1 , R ^a4-1 and R ^a6-1 each independently represent a single bond, —CH ₂ — or —CH ₂ CH ₂ —. L ¹ and L ² are each independently more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, or -OCO-.

In one preferred embodiment of the present invention, at least one of G ¹ and G ² in formula (II) is a divalent alicyclic hydrocarbon group, wherein the divalent alicyclic hydrocarbon group is , a polymerizable liquid crystal compound in which an optionally substituted divalent aromatic group Ar is linked by L ¹ and/or L ² of —COO— is used.

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 more preferably a single bond, —OR ^a10-1 —, —CH ₂ —, —CH ₂ CH ₂ —, —COOR ^a12-1 —, or OCOR ^a14-1 — . Here, R ^a10-1 , R ^a12-1 and R ^a14-1 each independently represent a single bond, —CH ₂ — or —CH ₂ CH ₂ —. B ¹ and B ² are each independently more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, -OCO- or -OCOCH ₂ CH ₂ - be.

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

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

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

Ar preferably has at least one selected from an optionally substituted aromatic hydrocarbon ring, an optionally substituted aromatic heterocycle, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include benzene ring, naphthalene ring, anthracene ring and the like, with benzene ring and naphthalene ring being preferred. Examples of the aromatic heterocyclic ring include furan ring, benzofuran ring, pyrrole ring, indole ring, thiophene ring, benzothiophene ring, pyridine ring, pyrazine ring, pyrimidine ring, triazole ring, triazine ring, pyrroline ring, imidazole ring, and pyrazole ring. , thiazole ring, benzothiazole ring, thienothiazole ring, oxazole ring, benzoxazole ring, and phenanthroline ring. 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 benzothiazole group. When Ar contains a nitrogen atom, the nitrogen atom preferably has a π electron.

In formula (II), the total number _Nπ of π electrons contained in the divalent aromatic group represented by Ar is preferably 8 or more, more preferably 10 or more, still more preferably 14 or more, especially It is preferably 16 or more. Also, 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 groups represented by the following formulas (Ar-1) to (Ar-23).

In formulas (Ar-1) to (Ar-23), * represents a linking moiety, and Z ⁰ , Z ¹ and Z ² each independently represent a hydrogen atom, a halogen atom, or an alkyl having 1 to 12 carbon atoms. a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, alkylthio group having 1 to 12 carbon atoms, N-alkylamino group having 1 to 12 carbon atoms, N,N-dialkylamino group having 2 to 12 carbon atoms, N-alkylsulfamoyl group having 1 to 12 carbon atoms or carbon represents an N,N-dialkylsulfamoyl group of numbers 2 to 12;

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

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

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

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

Examples of the aromatic hydrocarbon group for Y ¹ , Y ² and Y ³ include aromatic hydrocarbon groups having 6 to 20 carbon atoms such as phenyl group, naphthyl group, anthryl group, phenanthryl group and biphenyl group. , is preferably a naphthyl group, more preferably a phenyl group. The aromatic heterocyclic group includes a C4-20 group containing at least one heteroatom such as a nitrogen atom, an oxygen atom, a sulfur atom such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group and a benzothiazolyl group. An aromatic heterocyclic group can be mentioned, and a furyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group are preferable.

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

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

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

Among formulas (Ar-1) to (Ar-23), formulas (Ar-6) and (Ar-7) are preferable from the viewpoint of molecular stability.

In formulas (Ar-17) to (Ar-23), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is attached and Z ⁰ . Examples of the aromatic heterocyclic group include those described above as the aromatic heterocyclic ring that Ar may have, and examples thereof include pyrrole ring, imidazole ring, pyrroline ring, pyridine ring, pyrazine ring, pyrimidine ring, indole ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring and the like. This aromatic heterocyclic group may have a substituent. In addition, Y ¹ , together with the nitrogen atom and Z ⁰ to which it is attached, may be the aforementioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. Examples include benzofuran ring, benzothiazole ring, benzoxazole ring and the like. The compound represented by formula (II) can be produced, for example, according to the method described in JP-A-2010-31223.

The content of the polymerizable liquid crystal compound (B) in the polymerizable liquid crystal composition (B) constituting the retardation film is, for example, 70 to 99 parts per 100 parts by mass of the solid content of the polymerizable liquid crystal composition (B). .5 parts by mass, preferably 80 to 99 parts by mass, more preferably 90 to 98 parts by mass. When the content is within the above range, the orientation of the retardation film tends to be high. Here, the solid content refers to the total amount of components of the polymerizable liquid crystal composition (B) excluding volatile components such as solvents.

The polymerizable liquid crystal composition (B) may contain a polymerization initiator for initiating the polymerization reaction of the polymerizable liquid crystal compound (B). The polymerization initiator can be appropriately selected from those conventionally used in the field, and may be a thermal polymerization initiator or a photopolymerization initiator. A photopolymerization initiator is preferable because it can initiate a polymerization reaction. Preferable examples of the photopolymerization initiator that can be used in the polymerizable liquid crystal composition of the present invention include those exemplified above. In addition, the polymerizable liquid crystal composition (B) optionally contains a photosensitizer, a leveling agent, and additives exemplified as additives contained in the polymerizable liquid crystal composition of the present invention. good too. Examples of the photosensitizer and leveling agent include those exemplified above as usable in the polymerizable liquid crystal composition of the present invention.

The retardation film is prepared, for example, by adding a solvent to a polymerizable liquid crystal composition (B) containing a polymerizable liquid crystal compound (B) and optionally a polymerization initiator, additives, etc., and mixing and stirring. A composition (hereinafter also referred to as a "composition for forming a retardation film") is applied onto a substrate or an alignment film, the solvent is removed by drying, and the polymerizable liquid crystal compound (B) in the resulting coating film is can be obtained by curing with heating and/or active energy rays. Examples of the base material and/or the alignment film used for producing the retardation film include those exemplified above as those that can be used for producing the polarizing film of the present invention.

The solvent used for the retardation film-forming composition, the method for applying the retardation film-forming composition, the curing conditions using active energy rays, and the like are all the same as those that can be employed in the method for producing a polarizing film of the present invention. things are mentioned.

The thickness of the retardation film can be appropriately selected depending on the display device to be applied, but from the viewpoint of thinning and flexibility, it is preferably 0.1 to 10 μm, more preferably 1 to 5 μm. , 1 to 3 μm.

The polarizing plate of the present invention comprises the polarizing film or polarizing film of the present invention and a retardation film, preferably a substrate, an alignment film (especially a photo-alignment film), the polarizing film of the present invention, and a retardation film and Furthermore, other layers (protective film, adhesive layer, etc.) other than these may be included. In the polarizing plate of the present invention, the polarizing film or the polarizing film of the present invention and the retardation film may be laminated via an adhesive layer or a pressure-sensitive adhesive layer, and the retardation film-forming composition of the present invention may be applied to the polarizing plate of the present invention. The retardation film may be directly formed on the polarizing film or polarizing film of the present invention by directly coating the polarizing film or polarizing film.

The thickness of the polarizing plate of the present invention is preferably 10 to 300 μm, more preferably 20 to 200 μm, still more preferably 25 to 100 μm, from the viewpoint of flexibility and visibility of the display device.

<Display device>
The present invention includes the polarizing film of the present invention, the polarizing film of the present invention, or a display device comprising the polarizing plate of the present invention. The display device of the present invention can be obtained, for example, by bonding the polarizing film, polarizing film or polarizing plate of the present invention to the surface of the display device via an adhesive layer. A display device is a device having a display mechanism, and includes a light-emitting element or a light-emitting device as a light source. Examples of display devices include liquid crystal displays, organic electroluminescence (EL) displays, inorganic electroluminescence (EL) displays, touch panel displays, electron emission displays (field emission displays (FED etc.), surface field emission displays). (SED)), electronic paper (display device using electronic ink or electrophoretic element), plasma display device, projection display device (grating light valve (GLV) display device, display device having digital micromirror device (DMD) etc.) and piezoelectric ceramic displays. The liquid crystal display device includes any of a transmissive liquid crystal display device, a transflective liquid crystal display device, a reflective liquid crystal display device, a direct view liquid crystal display device, a projection liquid crystal display device, and the like. These display devices may be display devices that display two-dimensional images, or may be stereoscopic display devices that display three-dimensional images. In particular, as the display device of the present invention, an organic EL display device and a touch panel display device are preferable, and an organic EL display device is particularly preferable.

・二色性色素：
アゾ色素；

・レベリング剤：
ポリアクリレート化合物（ＢＹＫ－３６１Ｎ；ＢＹＫ－Ｃｈｅｍｉｅ社製） １．２部
・溶剤：
ｏ－キシレン ４００部 <Preparation of Composition for Forming Polarizing Film>
The following components were mixed and stirred at 80° C. for 1 hour to obtain a polarizing film-forming composition (1). As the dichroic dye, an azo dye described in Examples of JP-A-2013-101328 was used.
・Polymerizable liquid crystal compound:

・Dichroic dye:
azo dyes;

・Leveling agent:
Polyacrylate compound (BYK-361N; manufactured by BYK-Chemie) 1.2 parts Solvent:
o-xylene 400 parts

In the same manner as for the polarizing film-forming composition (1), except that the compound shown in Table 1 as a photopolymerization initiator was mixed in the amount shown in Table 2, Polarizing film-forming compositions (2) to (10) were obtained. The amount of the photopolymerization initiator added in Table 2 indicates the amount with respect to 100 parts by mass of the polymerizable liquid crystal compound in the polarizing film-forming composition (1).

<Structure of photoinitiator>
Photopolymerization initiators used in Examples and Comparative Examples are as follows.

<Measurement of liquid crystal phase transition temperature change T1-T2>
(1) Formation of alignment film A 2% by mass aqueous solution of polyvinyl alcohol (polyvinyl alcohol 1000 fully saponified type, manufactured by Wako Pure Chemical Industries, Ltd.) (orientation polymer composition/composition for forming an alignment film) is placed on a glass substrate. ) was applied by a spin coating method, and after drying, a film having a thickness of 100 nm was formed. Subsequently, an alignment film was formed by performing a rubbing treatment on the surface of the obtained film. Rubbing treatment is performed using a semi-automatic rubbing device (trade name: LQ-008 type, manufactured by Joyo Engineering Co., Ltd.) with a cloth (trade name: YA-20-RW, manufactured by Yoshikawa Kako Co., Ltd.) with a pushing amount of 0.15 mm. , 500 rpm and 16.7 mm/s.

(2) Measurement of T1 A mixture composition in which 90 parts of (A-6), 10 parts of (A-7), and 400 parts of o-xylene are uniformly mixed by stirring at 80 ° C. for 1 hour as a polymerizable liquid crystal compound. got The resulting composition was applied onto the alignment film-attached glass by a spin coating method and dried by heating on a hot plate at 130° C. for 3 minutes to remove o-xylene as a solvent. Then, it was quickly cooled to room temperature to obtain a dry film of a polymerizable liquid crystal compound. The dried film was again heated to 130° C. on a hot plate, then cooled to 23° C. at a rate of 5° C./min, and observed with a polarizing microscope to measure the phase transition temperature. As a result, the phase transitioned to the nematic liquid crystal phase at 113.8°C, the phase transition to the smectic A phase at 109.7°C, the phase transition to the smectic B phase at 92.8°C, and the smectic B phase until the temperature reached 23°C. confirmed to maintain Since the smectic B phase was the liquid crystal phase that appeared at the lowest temperature in the above process, T1 was defined as 92.8° C., which is the phase transition temperature to the smectic B phase.

(3) Measurement of T2 Except that photopolymerization initiators A to I were added to the above mixed composition at 5 parts by mass with respect to 100 parts by mass of the polymerizable liquid crystal compound, T1 was measured exactly as in (2) above. A dry film consisting of a mixture of a photopolymerization initiator and a polymerizable liquid crystal compound was obtained by the same method. As a result of measuring the phase transition temperature by the same method as the measurement of T1 in (2) above, the smectic B phase was found to be the liquid crystal phase exhibited at the lowest temperature side in all the mixtures. Table 3 shows the phase transition temperature (T2) to the liquid crystal phase that appears at the lowest temperature side when each photopolymerization initiator is contained.

・溶剤：
ｏ－キシレン ９８部 Example 1
(1) Preparation of photo-alignment film on substrate (i) Preparation of composition for forming photo-alignment film The following components described in JP-A-2013-033249 are mixed, and the resulting mixture is heated at 80°C for 1 hour. By stirring, a composition for forming a photo-alignment film was obtained.
・Photo-alignable polymer:

·solvent:
o-xylene 98 parts

(ii) Formation of photo-alignment film A triacetyl cellulose film (KC8UX2M, manufactured by Konica Minolta, Inc.) was used as a substrate, and the film surface was subjected to corona treatment, and then the composition for forming a photo-alignment film was applied. and 120° C. to obtain a dry film. A photo-alignment film was formed by irradiating polarized UV onto this dried film to obtain a film with a photo-alignment film. The polarized UV treatment was performed using a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.) under the condition that the intensity measured at a wavelength of 365 nm was 100 mJ.

(2) Preparation of polarizing film On the film with the photo-alignment film obtained as described above, the polarizing film-forming composition (2) is applied by a bar coating method (#9 30 mm / s) and dried at 120 ° C. The polymerizable liquid crystal compound was dried by heating in an oven for 1 minute to cause a phase transition to a liquid phase, and then cooled to room temperature to cause a phase transition of the polymerizable liquid crystal compound to a smectic liquid crystal state. Next, using a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.), the layer formed from the composition for forming a polarizing film is irradiated with ultraviolet rays at an exposure amount of 1000 mJ/cm ² (365 nm standard). Thus, the polymerizable liquid crystal compound contained in the dry film was polymerized while maintaining the smectic liquid crystal state of the polymerizable liquid crystal compound, and a polarizing film was formed from the dry film. When the film thickness of the polarizing film at this time was measured with a laser microscope (OLS3000 manufactured by Olympus Corporation), it was 2.3 μm. What is thus obtained is a polarizer comprising a polarizing film and a substrate.
This polarizing film was subjected to X-ray diffraction measurement by irradiating X-rays from the absorption axis direction of the polarizing film using an X-ray diffractometer X'Pert PRO MPD (manufactured by Spectris Co., Ltd.). A sharp diffraction peak (Bragg peak) with a peak half width (FWHM) of about 0.17° was obtained near 0.2°. When X-rays were irradiated from the direction of the transmission axis of the polarizing film and the same X-ray diffraction measurement was performed, a similar sharp diffraction peak (Bragg peak) was obtained, and the order period (d ) is about 4.4 Å, confirming the formation of a structure reflecting a higher-order smectic phase.

(3) Preparation of polarizing film laminate Furthermore, after subjecting the surface of the polarizing film of the polarizer obtained in the same manner as described above to corona treatment, the corona-treated surface was coated with 100 parts of water and carboxyl group-modified polyvinyl alcohol [ "Kuraray Poval KL318" manufactured by Kuraray Co., Ltd.] 7 parts, and a water-soluble polyamide epoxy resin as a thermal cross-linking agent ["Sumireze Resin 650" obtained from Sumika Chemtex Co., Ltd. (an aqueous solution with a solid content concentration of 30% by mass) ] to which 3.5 parts was added (viscosity: 92 cP) was applied using a wire bar coater (#30). By drying at 80° C. for 5 minutes, the aqueous solution was dried to form a protective layer, thereby producing a polarizer with a protective layer. Furthermore, on the protective layer, glass (Eagle XG manufactured by Corning Inc.) is laminated via an adhesive layer formed from a pressure-sensitive adhesive (manufactured by Lintec Corporation, film thickness 25 μm) to form the polarizing film of Example 1. A laminate was obtained.

Instead of the polarizing film-forming composition (2), Examples 2-8 and Comparative Polarizing film laminates of Examples 1 to 4 were obtained.

<Measurement of Absorption Axis Direction/Transmission Axis Direction Absorbance>
The absorption axial absorbance (MD) and the transmission axial absorbance (TD) of the dry film (before polymerization) and the polarizing film laminate (after polymerization) of the composition for forming a polarizing film before irradiation with ultraviolet rays were measured as follows. was measured and listed in Table 4. The absorbance along the absorption axis (MD) and the absorbance along the transmission axis (TD) in the wavelength range of 550 nm were measured using a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation) and a folder with a polarizer set. Measured by the beam method. The folder was provided with a mesh that cuts the amount of light by 50% on the reference side. The dichroic ratio DR was calculated based on the following (formula 2).
DR = MD/TD (Formula 2)

The polarizing films (Examples 1 to 8) produced from the polymerizable liquid crystal composition (composition for forming a polarizing film) of the present invention had a small change in the dichroic ratio DR before and after polymerization, and the dichroic ratio after polymerization. It was confirmed to be excellent in DR.

Claims (16)

A polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound having at least one polymerizable group and exhibiting smectic liquid crystallinity, a dichroic dye, and a photopolymerization initiator, wherein the photopolymerization initiator is the Formula (1) in relation to the polymerizable liquid crystal compound:
0°C ≤ T1-T2 ≤ 12.0°C (1)
[Wherein, T1 is the liquid crystal expressed at the lowest temperature when the phase transition temperature is measured while the polymerizable liquid crystal compound is heated to 130° C. in the atmosphere and then cooled to 23° C. at 5° C./min. Phase transition temperature, T2 is a mixture of 100 parts by mass of the polymerizable liquid crystal compound and 5 parts by mass of the photopolymerization initiator, after heating to 130 ° C. in the atmosphere 5 ° C./min. It is the phase transition temperature to the liquid crystal phase that is expressed on the lowest temperature side when measuring the phase transition temperature while cooling to 23 ° C.]
A polymerizable liquid crystal composition that satisfies 2. The polymerizable liquid crystal composition according to claim 1, further comprising a solvent. 3. The polymerizable liquid crystal composition according to claim 1, wherein the polymerizable group possessed by the polymerizable liquid crystal compound is an acryloyloxy group or a methacryloyloxy group. 4. The polymerizable liquid crystal composition according to any one of claims 1 to 3, wherein the dichroic dye is an azo dye. 5. The polymerizable liquid crystal composition according to claim 1, wherein the photopolymerization initiator has a weight average molecular weight of 500 or more and 2000 or less. 6. The polymerizable liquid crystal composition according to any one of claims 1 to 5, comprising 1 to 10 parts by mass of a photopolymerization initiator with respect to 100 parts by mass of the polymerizable liquid crystal compound. A polarizing film, which is a cured product of the polymerizable liquid crystal composition according to any one of claims 1 to 6, comprising the formula (2):
DR = MD/TD (2)
[Wherein, DR represents the dichroic ratio of the dichroic dye contained in the polarizing film, MD represents the absorbance in the direction of the absorption axis of the polarizing film at a wavelength of 550 nm, and TD represents the absorbance at a wavelength of 550 nm. It represents the absorbance in the transmission axis direction of the polarizing film. ]
The polarizing film, wherein the dichroic dye has a dichroic ratio (DR) of 47.7 or more. A polarizing film which is a cured product of the polymerizable liquid crystal composition according to any one of claims 1 to 6, wherein the polarizing film exhibits a Bragg peak in X-ray diffraction measurement. 9. The polarizing film according to claim 7, which has a thickness of 0.1 to 5 μm. A polarizing film comprising the polarizing film according to any one of claims 7 to 9 and a transparent film. A polarizing plate comprising the polarizing film according to any one of claims 7 to 9 or the polarizing film according to claim 10 and a retardation film. The retardation film has the formula (X):
100≦Re(550)≦180 (X)
[Wherein, Re (550) represents an in-plane retardation value at a wavelength of 550 nm]
and the angle formed by the slow axis of the retardation film and the absorption axis of the polarizing film is substantially 45 °. The retardation film has the formula (Y):
Re(450)/Re(550) < 1 (Y)
[Wherein, Re (450) and Re (550) represent in-plane retardation values at wavelengths of 450 nm and 550 nm, respectively]
13. The polarizing plate according to claim 11 or 12 , which satisfies: 14. The polarizing plate according to any one of claims 11 to 13 , wherein the retardation film comprises a polymer in an aligned state of the polymerizable liquid crystal compound. A display device comprising the polarizing film according to claim 10 or the polarizing plate according to any one of claims 11 to 14 . forming a coating film of the polymerizable liquid crystal composition according to any one of claims 1 to 6;
removing solvent from the coating;
raising the temperature to a temperature at which the polymerizable liquid crystal compound undergoes a phase transition to a liquid phase or higher, and then lowering the temperature to cause the polymerizable liquid crystal compound to undergo a phase transition to a smectic phase;
A method for producing a polarizing film, comprising polymerizing a polymerizable liquid crystal compound while maintaining the smectic phase.