JP7441005B2 - Composition for forming polarizing film, polarizing film, polarizing plate, and manufacturing method thereof - Google Patents

Description

The present invention relates to a composition for forming a polarizing film, a polarizing film, a polarizing plate, and a method for manufacturing the same.

Conventionally, a polarizing plate has been used in a flat panel display (FPD) by being bonded to an image display element such as a liquid crystal cell or an organic EL display element. As such a polarizing plate, triacetylcellulose is applied to at least one surface of a polarizer, which is made by adsorbing and orienting a dichroic compound such as iodine or dichroic dye to a polyvinyl alcohol resin film. Polarizing plates having a structure in which protective layers such as films are laminated are widely used.

In recent years, with the demand for thinner flat panel display devices, there has also been a demand for thinner polarizing plates and polarizing films, which are one of their constituent elements. Plates and polarizing films have been proposed. For example, Patent Document 1 discloses a polarizer containing a dichroic dye and a polymer formed from a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase. Further, Patent Document 2 discloses a polymerizable liquid crystal composition in which a polymerizable liquid crystal compound exhibiting a smectic phase and a dichroic dye are dissolved in a solvent, and a polarizing film can be formed by a wet coating method. Further, Patent Document 3 discloses a thin polarizing film that includes a plurality of dichroic dyes and a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase and exhibits polarization performance in the entire visible light range.

Patent No. 4719156 JP2012-083734A JP2013-210624A

Polarizing plates and polarizing films (polarizers) such as those disclosed in the above patent documents generally include a polarizing film-forming composition containing a polymerizable liquid crystal compound and a dichroic dye together with a solvent on a film such as a base film. The polymerizable liquid crystal compound is produced through the steps of applying the polymerizable liquid crystal compound to a liquid crystal state to form a coating film, and heating and drying the coating film to cause a phase transition of the polymerizable liquid crystal compound to a liquid crystal state. The present inventors have discovered that in such a process, if the solvent evaporates from the coating film before the polymerizable liquid crystal compound undergoes a phase transition to the liquid crystal state, the polymerizable liquid crystal compound tends to precipitate as microcrystals. . If such microcrystals precipitate, it is difficult to obtain a good mixed inclusion state of the polymerizable liquid crystal compound and the dichroic dye even if heat drying is performed afterwards, and the resulting polarizing film may have missing dots or misalignment. This may cause defects. The precipitation of such microcrystals is thought to be due to the fact that smectic liquid crystals have a structure closer to crystals than general nematic liquid crystals, and in polarizing films formed from polymerizable liquid crystal compounds that exhibit smectic liquid crystal properties, This is particularly problematic.

Therefore, an object of the present invention is to provide a composition for forming a polarizing film that can form a polarizing film that is free from missing dots and orientation defects and has a high degree of orientational order.

The present inventors 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 embodiments.
[1] Contains a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity, a dichroic dye, and at least two organic solvents, wherein the organic solvent has a temperature of −20° C. or higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound. A composition for forming a polarizing film, comprising an organic solvent A having a boiling point higher than 50°C and an organic solvent B having a boiling point higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound by more than 50°C.
[2] The content of organic solvent A is 51 to 99 parts by mass and the content of organic solvent B is 1 to 49 parts by mass, based on 100 parts by mass of all organic solvents contained in the composition for forming a polarizing film. The composition for forming a polarizing film according to [1].
[3] The boiling point of organic solvent A is 0°C or more and 50°C or less higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound, and the boiling point of organic solvent B is 50°C or more higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound. The composition for forming a polarizing film according to [1] or [2] above, which is higher than 150°C.
[4] The composition for forming a polarizing film according to any one of [1] to [3] above, further comprising a polymerization initiator.
[5] The composition for forming a polarizing film according to any one of [1] to [4] above, wherein the organic solvent A is a ketone solvent or an aromatic solvent.
[6] The composition for forming a polarizing film according to any one of [1] to [5] above, wherein the organic solvent B is selected from the group consisting of glycol solvents, ketone solvents, and amide solvents.
[7] The composition for forming a polarizing film according to any one of [1] to [6] above, wherein the solid content of the composition for forming a polarizing film is 5 to 40% by mass.
[8] The composition for forming a polarizing film according to [7] above, wherein the proportion of the polymerizable liquid crystal compound in the solid content is 40 to 99.9% by mass.
[9] The composition for forming a polarizing film according to [7] or [8] above, wherein the proportion of the dichroic dye in the solid content is 1 to 20% by mass.
[10] A cured product of the composition for forming a polarizing film according to any one of [1] to [9] above, which is polarized light in which a polymerizable liquid crystal compound and/or a polymer thereof is oriented in a smectic liquid crystal state. film.
[11] The polarizing film according to [10] above, which provides a Bragg peak in X-ray diffraction measurement.
[12] A polarizing plate comprising the polarizing film, a base material, and an alignment film according to [10] or [11] above.
[13] Forming a coating film of the composition for forming a polarizing film according to any one of [1] to [9] above,
heating and drying the coating film to a temperature equal to or higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound contained in the composition for forming a polarizing film, and then lowering the temperature to cause the polymerizable liquid crystal compound to undergo a phase transition to a smectic liquid crystal phase; ,
A method for producing a polarizing plate, comprising forming a polarizing film by polymerizing a polymerizable liquid crystal compound while maintaining the smectic liquid crystal phase.
[14] The method for producing a polarizing plate according to [13] above, comprising forming a coating film of a composition for forming a polarizing film on a photo-alignment film, the method comprising:
Forming a coating film from a composition containing a polymer or monomer and a solvent that generates an orientation regulating force when exposed to light;
Drying and removing the solvent from the coating film to obtain a dry coating film, and
irradiating the dried coating film with polarized ultraviolet light;
A method comprising:

According to the present invention, it is possible to provide a composition for forming a polarizing film that can form a polarizing film that is free from missing dots and orientation defects and has a high degree of orientational order.

Embodiments of the present invention will be described in detail below. Note that the scope of the present invention is not limited to the embodiments described here, and various changes can be made without departing from the spirit of the present invention.

<Polarizing film forming composition>
The composition for forming a polarizing film of the present invention contains a polymerizable liquid crystal compound (hereinafter also referred to as "polymerizable liquid crystal compound (A)") exhibiting smectic liquid crystallinity. By using a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity, a polarizing film with a high degree of orientation 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 better to exhibit a higher order smectic phase (higher order smectic liquid crystal state). preferable. Here, the higher-order smectic phases include 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 preferred. The liquid crystal may be thermotropic liquid crystal or lyotropic liquid crystal, but thermotropic liquid crystal is preferable because it allows precise control of the film thickness. The polymerizable liquid crystal compound may be a monomer, but may also be an oligomer or a polymer in which a polymerizable group is polymerized.

The polymerizable liquid crystal compound (A) is not particularly limited as long as it exhibits smectic liquid crystallinity, and any known polymerizable liquid crystal compound can be used.
Examples of the polymerizable liquid crystal compound (A) include a compound represented by formula (A1) and a polymer of the compound (hereinafter, the compound and the polymer are collectively referred to as "polymerizable liquid crystal compound (A1)") ).
U ¹ -V ¹ -W ¹ -X ¹ -Y ¹ -X ² -Y ² -X ³ -W ² -V ² -U ² (A1)
[In formula (A1),
X ¹ , X ² and X ³ each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group; The hydrogen atom contained in the hydrocarbon group of the formula is 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. The carbon atoms 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 , X ² and X ³ is a 1,4-phenylene group which may have a substituent or a cyclohexane-1,4-diyl group which may have a substituent. It is.
Y ¹ and Y ² are each independently a single bond or a divalent linking group.
U ¹ represents a hydrogen atom or a polymerizable group.
U ² 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 alkanediyl group having 1 to 20 carbon atoms which may have a substituent, 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 , X ² and X ³ are preferably a 1,4-phenylene group which may have a substituent or a 1,4-phenylene group which may have a substituent, independently of each other. a cyclohexane-1,4-diyl group which may have a substituent, and at least one of X ¹ , X ² and X ³ is a 1,4-phenylene group which may have a substituent or a substituent is a cyclohexane-1,4-diyl group which may have In particular, X ¹ and X ³ are preferably cyclohexane-1,4-diyl groups which may have substituents, and the cyclohexane-1,4-diyl group is trans-cyclohexane-1,4-diyl. More preferably, it is a 1,4-diyl group. The optional substituents of the 1,4-phenylene group which may have a substituent or the cyclohexane-1,4-diyl group which may have a substituent include a methyl group, an ethyl group, Examples include alkyl groups having 1 to 4 carbon atoms such as butyl groups, cyano groups, and halogen atoms such as chlorine atoms and fluorine atoms. Preferably it is unsubstituted. Moreover, when Y ¹ and Y ² have the same structure, it is preferable that at least one of X ¹ , X ² and X ³ has a different structure. When at least one of X ¹ , X ² and X ³ has a different structure, smectic liquid crystallinity tends to occur easily.

Y ¹ and Y ² each independently represent -CH ₂ CH ₂ -, -CH ₂ O-, -CH ₂ CH ₂ O-, -COO-, -OCOO-, single bond, -N=N-, -CR ^a =CR ^b -, -C≡C-, -CR ^a =N- or -CO-NR ^a - is 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 Y ² is more preferably -CH ₂ CH ₂ - or CH ₂ O-. Moreover, when X ¹ , X ² and X ³ all have the same structure, it is preferable that Y ¹ and Y ² have different structures. When Y ¹ and Y ² have different structures, smectic liquid crystallinity tends to occur easily.

U ² is a polymerizable group. U ¹ is a hydrogen atom or a polymerizable group, preferably a polymerizable group. It is preferable that both U ¹ and U ² are polymerizable groups, and it is preferable that both U 1 and U 2 are radically polymerizable groups. Examples of the polymerizable group 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 these, radically polymerizable groups are preferred, acryloyloxy groups, methacryloyloxy groups, vinyl groups, and vinyloxy groups are more preferred, and acryloyloxy groups and methacryloyloxy groups are preferred. The polymerizable group represented by U ¹ and the polymerizable group represented by U ² may be different from each other, but are preferably of the same type.

Examples of the alkanediyl group represented by V ¹ and V ² include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, and a pentane-1,3-diyl group. 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 group and icosane-1,20-diyl group. 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 optional substituents of the alkanediyl group include a cyano group and a halogen atom, but the alkanediyl group is preferably unsubstituted and is an unsubstituted linear alkanediyl group. is more preferable.

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

Examples of the polymerizable liquid crystal compound (A1) include compounds represented by formulas (A-1) to (A-25). When the polymerizable liquid crystal compound (A1) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably in the 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 compound 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 (A1), one type may be used alone, or two or more types may be used in combination.

The polymerizable liquid crystal compound (A1) is described by Lub et al., Recl. Trav. Chim. It can be produced by the known method described in Pays-Bas, 115, 321-328 (1996), or Japanese Patent No. 4719156.

The composition for forming a polarizing film 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 viewpoint of obtaining a polarizing film with a high degree of orientational order, the ratio of the polymerizable liquid crystal compound (A) to the total mass of all polymerizable liquid crystal compounds in the composition for forming a polarizing film is preferably 51% by mass or more, more preferably is 70% by mass or more, more preferably 90% by mass or more of the polymerizable liquid crystal compound is the polymerizable compound (A), and all (100% by mass) may be the polymerizable liquid crystal compound (A).

The content of the polymerizable liquid crystal compound in the composition for forming a polarizing film of the present invention is preferably 40 to 99.9% by mass, more preferably 60 to 99.9% by mass, based on the solid content of the composition for forming a polarizing film. .9% by mass, 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 this specification, the solid content refers to the total amount of components excluding the solvent from the composition for forming a polarizing film.

The composition for forming a polarizing film of the present invention contains a dichroic dye. Here, the dichroic dye refers to a dye that has a property that the absorbance in the long axis direction of the molecule is different from the absorbance in 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 types of dyes or pigments may be used in combination, or a dye and a pigment may be used in combination.

The dichroic dye preferably has 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, tetrakisazo dyes, and stilbene azo dyes, with bisazo dyes and trisazo dyes being preferred, such as compounds represented by formula (I) (hereinafter referred to as "compounds"). (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 which may have a substituent, a naphthyl group which may have a substituent, or a naphthyl group which may have a substituent. Represents a good monovalent heterocyclic group. K ² is a p-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, or a divalent heterocycle which may have a substituent. represents a group. p represents an integer from 1 to 4. When p is an integer of 2 or more, a plurality of K ² may be the same or different from each other. The -N=N- bond may be replaced by a -C=C-, -COO-, -NHCO-, or -N=CH- bond within a range that exhibits absorption in the visible region. ]

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

As a substituent optionally possessed by the phenyl group, naphthyl group, and monovalent heterocyclic group in K ¹ and K ³ , and the p-phenylene group, naphthalene-1,4-diyl group, and divalent heterocyclic group in 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 refers to an amino group having one or two alkyl groups having 1 to 6 carbon atoms, or two It refers to an amino group in which substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms.An unsubstituted amino group is _-NH2 .

［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 of formulas (I-1) to (I-6) are preferred.

[In formulas (I-1) to (I-8),
B ¹ to B ³⁰ each independently represent 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 the definition of unsubstituted amino group is as above), represents a chlorine atom or a trifluoromethyl group.
n1 to n4 each independently represent an integer of 0 to 3.
When n1 is 2 or more, the plurality of ^B2s may be the same or different from each other,
When n2 is 2 or more, the plurality of ^B6s may be the same or different from each other,
When n3 is 2 or more, multiple ^B9s may be the same or different from each other,
When n4 is 2 or more, the plurality of ^B14s may be the same or different from each other. ]

［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。］ The anthraquinone dye is preferably a compound represented by formula (I-9).

[In formula (I-9),
R ¹ to R ⁸ 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－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。］ The oxazone dye is preferably a compound represented by formula (I-10).

[In 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。 The acridine dye is preferably a compound represented by formula (I-11).

[In 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 in R ^x includes methyl group, ethyl group, propyl group, butyl group, pentyl group. Examples of the aryl group having 6 to 12 carbon atoms include phenyl group, tolyl group, xylyl group, and naphthyl group.

［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（２－１３）中、
Ｄ^３およびＤ^４は、互いに独立に、式（１－１３ａ）～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。］ The cyanine dye is preferably a compound represented by formula (I-12) or a compound represented by formula (I-13).

[In 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 from 1 to 3. ]

[In formula (2-13),
D ³ and D ⁴ each independently represent a group represented by any one of formulas (1-13a) to (1-13h).

n6 represents an integer from 1 to 3. ]

The content of the dichroic dye in the composition for forming a polarizing film of the present invention can be appropriately determined depending on the type of dichroic dye used, but it is preferably based on the solid content of the composition for forming a polarizing film. is 1 to 60% by weight, more preferably 1 to 20% by weight, and even more preferably 1 to 15% by weight. When the content of the dichroic dye is within the above range, it is difficult to disturb the orientation of the polymerizable liquid crystal compound, and a polarizing film having a high degree of orientational order can be obtained.

The composition for forming a polarizing film of the present invention contains at least two kinds of organic solvents. The two organic solvents include an organic solvent A having a boiling point higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound by -20°C or more and 50°C or less, and an isotropic phase transition temperature of the polymerizable liquid crystal compound. At least an organic solvent B having a boiling point higher than 50° C. is included. The composition for forming a polarizing film of the present invention contains at least two kinds of organic solvents having different boiling points as described above, so that the coating film of the composition for forming a polarizing film is heated and dried to cause a phase transition of the polymerizable liquid crystal compound to a liquid crystal state. The solvent is difficult to volatilize before the process (hereinafter also referred to as the "heat drying process"), but the solvent is easily removed by drying during the heat drying process, making it difficult to cause orientation defects or missing dots.A polarizing film with excellent polarizing performance. can be obtained. When the composition for forming a polarizing film of the present invention contains two or more types of polymerizable liquid crystal compounds, organic solvents A and B each contain a mixture of the polymerizable liquid crystal compounds contained in the composition for forming a polarizing film. Selected based on isotropic phase transition temperature.

Organic solvent A usually dissolves the polymerizable liquid crystal compound and the dichroic dye, facilitates the creation of a good mixed inclusion state of the polymerizable liquid crystal compound and the dichroic dye in the coating film, and also improves the composition for forming a polarizing film. It functions to adjust the solid content concentration and viscosity of substances. In particular, compounds that generally exhibit smectic liquid crystal properties tend to have high viscosity, and by including organic solvent A in the composition for forming a polarizing film, the composition becomes easier to handle, and as a result, the formation of a polarizing film becomes easier. It becomes easier. In order to suppress the organic solvent from volatilizing from the coating film before the heating drying process of the coating film of the polarizing film forming composition, the boiling point of organic solvent A is set to the polymerizable liquid crystal compound contained in the polarizing film forming composition. higher than the isotropic phase transition temperature of -20°C to 50°C, preferably 0°C to 50°C, more preferably 10°C to 50°C, more preferably 20°C to 40°C. If the boiling point of organic solvent A is more than -20°C lower than the isotropic phase transition temperature of the polymerizable liquid crystal compound, the organic solvent will easily volatilize before the heating drying process, and microcrystals of the polymerizable liquid crystal compound will easily precipitate. Become. In addition, if the boiling point of organic solvent A is higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound by more than 50°C, the volatilization of the solvent before the heating drying process can be suppressed, but the solvent will be difficult to volatilize during the heating drying process. This tends to cause alignment defects, and the heating temperature must be raised to remove the solvent, which tends to damage the film such as the base material. At the same time, since the amount of solvent remaining after the heat drying process can be reduced, it is possible to suppress the occurrence of orientation defects caused by the residual solvent. One type of organic solvent A may be used alone, or two or more types may be used in combination.

Organic solvent B is a high boiling point solvent and has the function of providing a moisturizing effect on the coating film before the heat drying process. From the viewpoint of suppressing volatilization from the coating film before the heat drying process, the boiling point of organic solvent B is higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound contained in the composition for forming a polarizing film by more than 50°C. , preferably 55°C or more, preferably 150°C or less, more preferably 60°C or more and 150°C or less, still more preferably 60°C or more and 120°C or less. By including organic solvent B having a boiling point higher in the above range than the isotropic phase transition temperature of the polymerizable liquid crystal compound, it is possible to effectively suppress volatilization of the organic solvent from the coating film before the heating drying step. , it is possible to maintain a good mixed and inclusive state of the polymerizable liquid crystal compound and the dichroic dye in the coating film. Thereby, it is possible to effectively suppress the occurrence of missing dots in the polarizing film obtained. The organic solvent B may be used alone or in combination of two or more.

The difference between the boiling points of organic solvent A and organic solvent B is preferably 20°C or higher, more preferably 30°C or higher, preferably 120°C or lower, and more preferably 100°C or lower. When the boiling points of organic solvents A and B have the above relationship, the effect of suppressing the generation of microcrystals of the polymerizable liquid crystal compound before the heating drying process of the coating film of the polarizing film forming composition and the ease of removal of the solvent during the heating drying process are achieved. It is easy to maintain a balance with the effect of polarization, and the resulting polarizing film is less likely to have missing dots or orientation defects.

Organic solvents A and B are capable of dissolving the polymerizable liquid crystal compound and dichroic dye based on the isotropic phase transition temperature of the polymerizable liquid crystal compound, depending on the polymerizable liquid crystal compound and dichroic dye used, respectively. It can be appropriately selected from known organic solvents. Examples of organic solvents include the following solvents:
Ketones such as methyl isobutyl ketone (116°C), cyclohexanone (156°C), cyclopentanone (131°C), methyl amyl ketone (151°C), isophorone (215°C), and γ-butyrolactone (GBL) (204°C) solvent;
Xylene (144°C), mesitylene (165°C), cumene (152°C), ethylbenzene (136°C), anisole (154°C), aniline (184°C), benzaldehyde (178°C), benzyl alcohol (205°C), benzoin Aromatic solvents such as methyl acid (199°C), ethyl benzoate (213°C), propyl benzoate (230°C), butyl benzoate (250°C), nitrobenzene (211°C), and tetralin (207°C);
Long chain hydrocarbon solvents such as octane (125°C), nonane (151°C), decane (174°C), undecane (196°C), dodecane (216°C);
Ethylene glycol monomethyl ether (124°C), ethylene glycol monoethyl ether (202°C), ethylene glycol-n-propyl ether (151°C), ethylene glycol-i-propyl ether (141°C), ethylene glycol-n-butyl ether ( 171°C), ethylene glycol monomethyl ether (124°C), diethylene glycol dimethyl ether (162°C), diethylene glycol diethyl ether (189°C), dipropylene glycol dimethyl ether (171°C), diethylene glycol monomethyl ether (194°C), diethylene glycol monoethyl ether ( 202℃), diethylene glycol monobutyl ether (230℃), diethylene glycol ethyl methyl ether (176℃), diethylene glycol butyl methyl ether (212℃), propylene glycol monomethyl ether (120℃), propylene glycol dimethyl ether (120℃), dipropylene glycol Monomethyl ether (188°C), dipropylene glycol dimethyl ether (171°C), propylene glycol dimethyl ether (97°C), tripropylene glycol dimethyl ether (215°C), triethylene glycol monomethyl ether (249°C), triethylene glycol dimethyl ether (216°C) ), tetraethylene glycol dimethyl ether (276°C), propylene glycol monomethyl ether acetate (146°C), ethylene glycol monomethyl ether acetate (145°C), ethylene glycol monomethyl ether acetate (145°C), diethylene glycol monoethyl ether acetate (217°C) , glycol-based solvents such as diethylene glycol monobutyl ether acetate (245°C);
Propyl acetate (102°C), butyl acetate (126°C), amyl acetate (149°C), ethyl lactate (155°C), methylmethoxypropionate (143°C), ethyl ethoxypropionate (170°C), isoamylpropionate pionate (156°C), isoamyl isobutyrate (179°C), ethyl butyrate (121°C), propyl butyrate (143°C), butyl butyrate (165°C), ethylene carbonate (244°C), propylene carbonate (242°C) Ester solvents such as;
Amide solvents such as N,N-dimethylformamide (153°C), N,N-dimethylacetamide (165°C), N-methylpyrrolidone (202°C), and γ-butyrolactam (245°C); and chlorobenzene (131°C) , 1,1,2,2,-tetrachloroethane (147°C) and other halogen-based solvents.

As the organic solvent A, it is more advantageous to select one that has high solubility for the polymerizable liquid crystal compound and the dichroic dye. In a preferred embodiment of the present invention, the organic solvent A is a ketone solvent or an aromatic solvent, more preferably an aromatic solvent. Further, as the organic solvent B, it is more advantageous to select one that has a high boiling point relative to the isotropic phase transition temperature of the polymerizable liquid crystal compound and has high solubility for the polymerizable liquid crystal compound and the dichroic dye. In a preferred embodiment of the present invention, the organic solvent B is selected from the group consisting of glycol solvents, ketone solvents, and amide solvents, more preferably glycol solvents, ketone solvents, and amide solvents having a boiling point of 150°C or higher. It is a solvent.

The content of organic solvent A in the composition for forming a polarizing film of the present invention is preferably 51 to 99 parts by mass, more preferably The amount is 60 parts by mass or more, more preferably 70 parts by mass or more, more preferably 95 parts by mass or less, even more preferably 90 parts by mass or less. Further, the content of organic solvent B is preferably 1 to 49 parts by mass, more preferably 5 parts by mass or more, and even more preferably The amount is 10 parts by mass or more, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. When the organic solvents A and B are contained within the above content ranges, the volatilization of the solvent is suppressed in the coating film before the heating drying process, resulting in a good mixed inclusion state of the polymerizable liquid crystal compound and the dichroic dye. In addition, in the heat drying process, it is possible to sufficiently remove the solvent even at a temperature near the phase transition temperature of the polymerizable liquid crystal compound without requiring excessive heating, and the remaining solvent can be removed. It is possible to suppress the resulting orientation defects and obtain a polarizing film with excellent polarizing performance. When organic solvent A and/or organic solvent B contain two or more types, the above content means the total amount of each of organic solvent A and/or organic solvent B. The composition for forming a polarizing film of the present invention may contain organic solvents other than organic solvents A and B, as long as the effects of the present invention are not impaired.

The composition for forming a polarizing film of the present invention preferably contains an organic solvent in an amount such that the solid content thereof is 5 to 40% by mass. In other words, the content of organic solvents in the composition for forming a polarizing film of the present invention (the total amount of organic solvents A and B, and other organic solvents if included) is the total mass of the composition for forming a polarizing film. It is preferably 60 to 95% by mass. When the content of the organic solvent is within the above range, it is possible to suppress the volatilization of the solvent in the coating film before heat drying, and in the heat drying process, the solvent can be easily dried and removed without unnecessary heating, and the remaining The amount of solvent can be reduced. Thereby, a polarizing film with excellent polarization performance can be obtained.

It is preferable that the composition for forming a polarizing film of the present invention contains a polymerization initiator. The polymerization initiator is a compound that can initiate the polymerization reaction of the polymerizable liquid crystal compound, and a photopolymerization initiator is preferable because it can initiate the polymerization reaction under lower temperature conditions. Specifically, photopolymerization initiators that can generate active radicals or acids by the action of light can be mentioned, and among them, photopolymerization initiators that can generate radicals by the action of light are preferred. Polymerization initiators can be used alone or in combination of two or more.

Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts, and sulfonium salts.

Examples of the benzoin compound include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

Examples of benzophenone compounds include benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone. and 2,4,6-trimethylbenzophenone.

Examples of alkylphenone compounds include diethoxyacetophenone, 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one, and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane. -1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1-[ 4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexylphenylketone and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one Examples include oligomers.

Examples of the acylphosphine oxide compound include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

As triazine compounds, 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-triazine, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine and 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine Examples include methyl)-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine.

A commercially available polymerization initiator can be used. Commercially available polymerization initiators include "Irgacure (registered trademark) 907", "Irgacure (registered trademark) 184", "Irgacure (registered trademark) 651", "Irgacure (registered trademark) 819", and "Irgacure (registered trademark)". 250'', ``Irgacure 369'' (Ciba Japan Co., Ltd.); Seiko Chemical Co., Ltd.); “Kayacure (registered trademark) BP100” (Nippon Kayaku Co., Ltd.); “Kayacure (registered trademark) UVI-6992” (manufactured by Dow Corporation); “Adeka Optomer SP-152” ”, “ADEKA Optomer SP-170” (ADEKA Co., Ltd.); “TAZ-A”, “TAZ-PP” (Japan Siberhegner Co., Ltd.); and “TAZ-104” (Sanwa Chemical Co., Ltd.), etc. .

When the composition for forming a polarizing film contains a polymerization initiator, the content can be appropriately determined depending on the type and amount of the polymerizable liquid crystal compound contained in the composition for forming a polarizing film. The amount is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 10 parts by weight, and even more preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the liquid crystal compound. When the content of the polymerization initiator is within the above range, polymerization can be carried out without disturbing the orientation of the polymerizable liquid crystal compound.

When the composition for forming a polarizing film contains a photopolymerization initiator, it may further contain a photosensitizer. By using a photosensitizer, the polymerization reaction of the polymerizable liquid crystal compound can be further promoted. Examples of photosensitizers include xanthone compounds such as xanthone and thioxanthone (2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and anthracene containing an alkoxy group (dibutoxyanthracene, etc.); phenothiazine and rubrene, etc. can be mentioned. The photosensitizers can be used alone or in combination of two or more.

The content of the photosensitizer in the composition for forming a polarizing film of the present invention may be appropriately determined depending on the type and amount of the photopolymerization initiator and the polymerizable liquid crystal compound. The amount is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 10 parts by weight, and even more preferably 0.5 to 8 parts by weight.

Moreover, the composition for forming a polarizing film of the present invention may contain a leveling agent. The leveling agent has the function of adjusting the fluidity of the composition for forming a polarizing film and making the coating film obtained by applying the composition for forming a polarizing film more flat. Examples include agents. 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. Leveling agents can be used alone or in combination of two or more.

Leveling agents containing polyacrylate compounds as main components include "BYK-350", "BYK-352", "BYK-353", "BYK-354", "BYK-355", "BYK-358N", " BYK-361N, BYK-380, BYK-381 and BYK-392 (BYK Chemie).

Leveling agents whose main component is a fluorine atom-containing compound include "Megafac (registered trademark) R-08", "Megafac (registered trademark) R-30", "R-90", "F-410", and "Megafac (registered trademark)". -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 Chemical Laboratories Co., Ltd.); Examples include "F-TOP EF301", "F-TOP EF303", "F-TOP EF351", and "F-TOP EF352" (Mitsubishi Materials Electronic Chemicals Co., Ltd.).

The content of the leveling agent in the composition for forming a polarizing film of the present invention is preferably 0.05 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, it is easy to horizontally align the polymerizable liquid crystal compound, and there is a tendency for a smoother polarizing film to be obtained with less unevenness.

In order to make the polymerization reaction of the polarizing film forming composition proceed more stably, the composition may contain an appropriate amount of a polymerization inhibitor, thereby controlling the degree of progress of the polymerization reaction of the polymerizable liquid crystal compound. Easier to control.

Examples of polymerization inhibitors include radical scavengers such as hydroquinone, alkoxy group-containing hydroquinone, alkoxy group-containing catechol (such as butylcatechol), pyrogallol, and 2,2,6,6-tetramethyl-1-piperidinyloxy radical. ; thiophenols; β-naphthylamines and β-naphthols.

When the composition for forming a polarizing film contains a polymerization inhibitor, the content can be adjusted as appropriate depending on the type and amount of the polymerizable liquid crystal compound, the amount of photosensitizer used, etc. The amount is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 10 parts by weight, and even more preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the compound. If the content of the polymerization inhibitor is within this range, polymerization can be carried out without disturbing the orientation of the polymerizable liquid crystal compound.

The composition for forming a polarizing film may contain additives other than a photopolymerization initiator, a leveling agent, a photosensitizer, and a polymerization inhibitor. Other additives include antioxidants, mold release agents, stabilizers, colorants such as bluing agents, flame retardants, and lubricants. When the polarizing film-forming composition contains other additives, the content of the other additives is more than 0% by mass and 20% by mass or less based on the solid content of the polarizing film-forming composition. It is preferably greater than 0% by mass and less than 10% by mass.

The solid content of the composition for forming a polarizing film of the present invention is preferably 5 to 40% by mass. If the solid content concentration of the composition for forming a polarizing film is equal to or higher than the above lower limit, the solvent will volatilize and microcrystals of the polymerizable liquid crystal compound will precipitate before the heating drying process of the coating film of the composition for forming a polarizing film. It is possible to prevent the occurrence of dot omission in the polarizing film. Moreover, when the solid content is below the above upper limit, the organic solvent can be easily removed in the heat drying step, and orientation defects are less likely to occur in the resulting polarizing film. Furthermore, since compounds exhibiting smectic liquid crystallinity generally have high viscosity, setting the solid content concentration within the above range has the advantage that coating becomes easier, resulting in easier formation of a polarizing film. In the present invention, the solid content of the composition for forming a polarizing film is more preferably 10% by mass or more, still more preferably 15% by mass or more, and more preferably 35% by mass or less, still more preferably 30% by mass or less. . The solid content concentration can be adjusted mainly by adjusting the amount of organic solvent and polymerizable liquid crystal compound.

The composition for forming a polarizing film of the present invention can usually be prepared by mixing and stirring a polymerizable liquid crystal compound, a dichroic dye, an organic solvent, and, if necessary, the above-mentioned additives.

The composition for forming a polarizing film of the present invention is less likely to cause missing dots or alignment defects, and can provide a polarizing film with a high degree of alignment order. Therefore, the present invention also includes a polarizing film obtained by curing the composition for forming a polarizing film of the present invention (that is, a cured product of the composition for forming a polarizing film). In the polarizing film of the present invention, the polymerizable liquid crystal compound and/or its polymer forming the polarizing film is preferably oriented in a smectic liquid crystal state. By aligning in a smectic liquid crystal state, the polarizing film of the present invention exhibits a high degree of alignment order.

A polarizing film with a high degree of orientational order can obtain a Bragg peak derived from a higher-order structure such as a hexatic phase or a crystal phase in X-ray diffraction measurement. The Bragg peak means a peak derived from a planar periodic structure of molecular orientation. It is preferable that the polarizing film formed from the composition for forming a polarizing film of the present invention exhibits a Bragg peak in X-ray diffraction measurement, and that the polymerizable liquid crystal compound and/or its polymer have molecules in the direction in which light is absorbed. It is more preferable to use "horizontal orientation". In the present invention, a polarizing film having a plane periodic interval of molecular orientation of 3.0 to 6.0 Å is preferable.

The polarizing film of the present invention can be manufactured, for example, according to the method for forming a polarizing film in the method for manufacturing a polarizing plate of the present invention, which will be described later.

The present invention also targets a polarizing plate comprising the polarizing film of the present invention. In one embodiment of the present invention, the polarizing plate of the present invention includes a base material and an alignment film in addition to the polarizing film of the present invention, and particularly preferably includes a base material and a photo-alignment film.

The polarizing plate of the present invention can be produced by, for example, forming a coating film of the composition for forming a polarizing film of the present invention,
The coating film is dried by heating to a temperature equal to or higher than the nematic-isotropic phase transition temperature of the polymerizable liquid crystal compound contained in the composition for forming a polarizing film, and then the temperature is lowered to transform the polymerizable liquid crystal compound into a smectic liquid crystal phase (smectic liquid crystal state). causing a phase transition to, and
It can be manufactured by a method including forming a polarizing film by polymerizing a polymerizable liquid crystal compound while maintaining the smectic liquid crystal phase (smectic liquid crystal state).

Formation of a coating film of the composition for forming a polarizing film can be performed, for example, by applying the composition for forming a polarizing film onto a substrate, an alignment film to be described later, or the like. Furthermore, when the polarizing plate of the present invention includes a retardation film or the like, the composition for forming a polarizing film may be directly applied thereon.

The substrate is typically a transparent substrate. When the base material is not installed on the display surface of the display element, for example, when a laminate obtained by removing the base material from the polarizing film is installed on the display surface of the display element, the base material does not need to be transparent. Transparent substrate refers to a substrate that has transparency that allows light, particularly visible light, to pass through, and transparency refers to the property that the transmittance for light rays with a wavelength of 380 to 780 nm is 80% or more. say. A specific example of the transparent base material is a translucent resin base material. Examples of resins constituting the translucent resin base material include polyolefins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene polymers; polyvinyl alcohol; polyethylene terephthalate; polymethacrylate ester; polyacrylate ester; triacetyl cellulose; Examples include cellulose esters such as diacetyl cellulose and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; polyphenylene sulfide and polyphenylene oxide. 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. Furthermore, cellulose ester base materials are also easily available on the market. Examples of commercially available cellulose ester base materials include "Fujitac Film" (Fuji Photo Film Co., Ltd.); "KC8UX2M", "KC8UY" and "KC4UY" (Konica Minolta Opto Co., Ltd.).

The thickness of the base material is usually 5 to 300 μm, preferably 20 to 200 μm, and more preferably 20 to 100 μm, since if it is too thin, the strength will decrease and the workability will tend to be poor.

Methods for applying the composition for forming a polarizing film onto a substrate include coating methods such as spin coating, extrusion, gravure coating, die coating, bar coating, and applicator methods, and printing such as flexography. Examples include known methods such as the method.

Next, the coating film obtained from the composition for forming a polarizing film is heated to a temperature equal to or higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound contained in the composition for forming a polarizing film, and at the same time, the solvent is dried and removed. Phase transition of a liquid crystal compound to a liquid phase. Thereafter, the temperature is lowered to cause a phase transition of the polymerizable liquid crystal compound to a smectic phase (smectic liquid crystal state).

The heating temperature of the coating film can be appropriately determined in consideration of the polymerizable liquid crystal compound used and the material of the film such as the base material forming the coating film. In order to bring the polymerizable liquid crystal compound into a sufficiently isotropic state while sufficiently removing the organic solvent, the heating temperature is preferably 1°C or more higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound, more preferably 5°C or more. The temperature is higher than 7°C, more preferably 7°C or higher. The upper limit of the heating temperature is not particularly limited, but is preferably 150° C. or lower, more preferably 130° C. or lower in order to avoid damage to the coating film, base material, etc. due to heating.

The heating time can be appropriately determined depending on the heating temperature, the type of polymerizable liquid crystal compound used, the type of organic solvent, its boiling point, its amount, etc., but is usually 0.5 to 10 minutes, preferably 1 to 5 minutes. It's a minute.

Before heating the polymerizable liquid crystal compound to a temperature higher than the isotropic phase transition temperature, the solvent in the coating film obtained from the film-forming composition is adjusted to an appropriate level under conditions such that the polymerizable liquid crystal compound contained in the coating film obtained from the film-forming composition does not polymerize. A pre-drying step may be provided for removal. By providing the drying step, the orientation of the polymerizable liquid crystal compound can be improved. Examples of drying methods include natural drying, ventilation drying, heating drying, and reduced pressure drying. The drying temperature (heating temperature) in the drying step depends on the type of polymerizable liquid crystal compound used, the type of organic solvent, and the boiling point. The temperature can be determined as appropriate depending on the amount and the like, but from the viewpoint of suppressing precipitation of microcrystals of the polymerizable liquid crystal compound, the temperature is usually 30 to 150°C, preferably 50 to 130°C. The drying time can be determined as appropriate depending on the drying temperature, the type of organic solvent used, etc., but is usually 0.1 to 5 minutes, preferably 0.1 to 3 minutes.

Next, in the dry coating film obtained by the heat drying, the polymerizable liquid crystal compound is polymerized while maintaining the smectic liquid crystal state of the polymerizable liquid crystal compound, so that the cured film of the polarizing film forming composition becomes a polarizing film. It is formed. As the polymerization method, a photopolymerization method is preferred. In photopolymerization, the light irradiated to the dry coating film depends on 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 the amount thereof is selected as appropriate. Specific examples include one or more types 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 these, ultraviolet light is preferable because it is easy to control the progress of the polymerization reaction and it is possible to use photopolymerization equipment that is widely used in this field. It is preferable to select the type of polymerizable liquid crystal compound and photopolymerization initiator contained in the forming composition in advance. Moreover, during polymerization, the polymerization temperature can also be controlled by irradiating the dry coating film with light while cooling it with an appropriate cooling means. By employing 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 with relatively low heat resistance is used. A patterned polarizing film can also be obtained by performing masking or development during photopolymerization.

The light source of the active energy rays includes a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, and a wavelength range of 380~ Examples include an LED light source that emits light at 440 nm, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

The ultraviolet irradiation intensity is usually 10 to 3,000 mW/cm ² . The ultraviolet irradiation intensity is preferably an intensity in a wavelength range effective for activating the photopolymerization initiator. The time for irradiating the light is usually 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and even more preferably 0.1 seconds to 1 minute. be. When irradiated once or multiple times with such ultraviolet irradiation intensity, 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 It is ² .

By performing photopolymerization, the polymerizable liquid crystal compound is polymerized while maintaining a liquid crystal state of a smectic phase, preferably a higher-order smectic phase, and a polarizing film is formed. Due to the action of the dichroic dye, the polarizing film obtained by polymerizing the polymerizable liquid crystal compound while maintaining the smectic phase liquid crystal state is different from the conventional host-guest type polarizing film, that is, from the nematic phase liquid crystal state. It has the advantage of higher polarizing performance than other polarizing films. Furthermore, 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 depending on the display device to which it is applied, and is preferably 0.5 to 10 μm, more preferably 1 to 5 μm, and still more preferably 1 to 3 μm.

The coating film of the composition for forming a polarizing film is preferably formed on the alignment film. The alignment film has an alignment regulating force that causes the polymerizable liquid crystal compound to align the liquid crystal in a desired direction. The alignment film is preferably one that has a solvent resistance that does not dissolve in the organic solvent contained in the composition for forming a polarizing film, and also has heat resistance during heat treatment for removing the solvent and aligning the polymerizable liquid crystal compound. . Examples of such an alignment film include an alignment film containing an alignment polymer, a photoalignment film formed from a composition containing a polymer and a solvent that generates an alignment regulating force when exposed to light, and a groove alignment film having a concavo-convex pattern or a plurality of grooves on the surface. , a stretched film stretched in the orientation direction, etc., and a photo-alignment film is preferred from the viewpoint of being less likely to generate static electricity or foreign matter and having excellent quality as an optical film.

Examples of oriented polymers include polyamides and gelatins having an amide bond in the molecule, polyimide having an imide bond in the molecule, and polyamic acid which is a hydrolyzate thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, Examples include polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylic esters. Among them, polyvinyl alcohol is preferred. The oriented polymers can be used alone or in combination of two or more.

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 base material, and then removing the solvent, or It is obtained by applying an oriented polymer composition to a substrate, removing the solvent, and rubbing (rubbing method). Examples of the solvent include those similar to those exemplified above as organic solvents that can be used in the composition for forming a polarizing film.

The concentration of the oriented polymer in the oriented polymer composition may be within a range that allows the oriented polymer material to be completely dissolved in the solvent, but it is preferably 0.1 to 20% in terms of solid content with respect to the solution. It is more preferably about .1 to 10%.

Commercially available alignment film materials may be used as they are as the alignment polymer composition. Commercially available alignment film materials include Sunever (registered trademark, manufactured by Nissan Chemical Industries, Ltd.), Optomer (registered trademark, manufactured by JSR Corporation), and the like.

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

Examples of methods for removing the solvent contained in the oriented polymer composition include natural drying, ventilation drying, heat drying, and reduced pressure drying.

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

As a method of imparting orientation regulating force by the rubbing method, a rubbing cloth is wrapped around a rotating rubbing roll, and an oriented polymer composition is applied to the substrate and annealed to form an oriented polymer composition on the surface of the substrate. Examples include a method of bringing oriented polymer films into contact with each other.

A photo-alignment film is usually made of a composition (hereinafter also referred to as a "composition for forming a photo-alignment film") containing a polymer or monomer and a solvent that has a photoreactive group and generates an alignment regulating force due to light. The solvent can be formed by drying and removing the solvent from the obtained coating film, and then irradiating the obtained dry coating film with polarized ultraviolet rays. A photo-alignment film is more preferable in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the polarized ultraviolet rays to be irradiated.

The photoreactive group refers to a group that produces liquid crystal alignment ability when irradiated with light. Specifically, groups that are involved in molecular alignment induction caused by light irradiation or photoreactions that are the origin of liquid crystal alignment ability, such as isomerization reactions, dimerization reactions, photocrosslinking reactions, or photodecomposition reactions, can be mentioned. Among these, groups that participate in a dimerization reaction or a photocrosslinking reaction are preferable because they have excellent orientation. The photoreactive group is preferably a group having an unsaturated bond, especially a double bond, such as a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), or a nitrogen-nitrogen double bond. Particularly preferred is a group having at least one selected from the group consisting of a double bond (N=N bond) and a carbon-oxygen double bond (C=O bond).

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

Among these, photoreactive groups that participate in photodimerization reactions are preferred, since the amount of polarized light irradiation required for photoalignment is relatively small, and it is easy to obtain a photoalignment film with excellent thermal stability and stability over time. Cinnamoyl and chalcone groups are preferred. As the polymer having a photoreactive group, one having a cinnamoyl group such that the end of the polymer side chain has a cinnamic acid structure is particularly preferred.

By applying the composition for forming a photo-alignment film onto a base material, a photo-alignment inducing layer can be formed on the base material. Examples of the solvent contained in the composition include those similar to those exemplified above as organic solvents that can be used in the composition for forming a polarizing film, and depending on the solubility of the polymer or monomer having a photoreactive group, It can be selected as appropriate.

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

Examples of the method for applying the composition for forming a photo-alignment film onto the substrate include the same method as the method for applying the alignment composition onto the substrate. Examples of methods for removing the solvent from the applied composition for forming a photo-alignment film include natural drying, ventilation drying, heating drying, and reduced pressure drying.

The temperature at which the solvent is removed by drying can be determined as appropriate depending on the type and amount of the solvent used, but is usually 30 to 150°C, preferably 60 to 130°C. The dry removal time is usually 0.1 to 10 minutes, preferably 0.5 to 5 minutes.

In order to irradiate polarized light, polarized ultraviolet rays can be irradiated from the base material side, and the polarized ultraviolet rays can be transmitted through the polarized ultraviolet rays. It may also be a form of irradiation. It is particularly preferable that the polarized ultraviolet light is substantially parallel light. The wavelength of the polarized ultraviolet rays to be irradiated is preferably in a wavelength range in which a photoreactive group of a polymer or monomer having a photoreactive group can absorb light energy. Specifically, ultraviolet rays with wavelengths in the range of 250 to 400 nm are particularly preferred. Examples of light sources used for the polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF. preferable. Among these, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are preferable because they emit a high intensity of ultraviolet light with a wavelength of 313 nm. Polarized ultraviolet rays can be irradiated 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.

Note that by performing masking when performing rubbing or polarized light irradiation, it is also possible to form a plurality of regions (patterns) in which the directions of liquid crystal alignment are different.

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 equal intervals, liquid crystal molecules are aligned in the direction along the grooves.

The groove alignment film can be obtained by exposing the surface of a photosensitive polyimide film to light through an exposure mask having pattern-shaped slits, followed by development and rinsing to form a concavo-convex pattern, and by using a plate with grooves on the surface. A method of forming a layer of uncured UV curable resin on a shaped master, transferring the formed resin layer to a base material, and then curing it; Examples include a method in which a rolled master having a plurality of grooves is pressed against each other to form irregularities, and then hardened.

The thickness of the alignment film (orientation film containing an alignment polymer or photo-alignment film) is usually in the range of 10 to 10,000 nm, preferably in the range of 10 to 1,000 nm, more preferably 500 nm or less, and even more preferably 10 to 10,000 nm. ~200 nm, particularly preferably from 50 to 150 nm.

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

Since the polarizing film and polarizing plate of the present invention have excellent polarizing performance, they can be suitably used in various display devices. 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. Display devices include liquid crystal display devices, organic electroluminescent (EL) display devices, inorganic electroluminescent (EL) display devices, touch panel display devices, electron emission display devices (field emission display devices (FEDs, etc.), surface field emission display devices) (SED)), electronic paper (display device using electronic ink or electrophoretic element), plasma display device, projection type display device (grating light valve (GLV) display device, display device with digital micromirror device (DMD)) etc.) and piezoelectric ceramic displays, organic EL display devices and touch panel display devices are particularly preferred, and organic EL display devices are particularly preferred. A display device including the polarizing plate of the present invention can be obtained by bonding the polarizing plate of the present invention to the surface of the display device via a pressure-sensitive adhesive or an adhesive.

Hereinafter, the present invention will be explained in more detail with reference to Examples. "%" and "parts" in the examples are mass % and parts by mass unless otherwise specified.

２部
・溶剤：
ｏ－キシレン ９８部 <Preparation of composition for forming photo-alignment film>
A composition for forming a photo-alignment film was obtained by mixing the following components described in JP-A-2013-033249 and stirring the resulting mixture at 80° C. for 1 hour.
・Photoalignable polymer:

2 parts/solvent:
o-xylene 98 parts

<Preparation of photo-alignment film base material>
A 100 mm x 100 mm triacetyl cellulose film (KC8UX2M, manufactured by Konica Minolta, Inc.) was used as a base material, and after corona treatment was applied to the film surface, the above composition for forming a photo-alignment film was applied, and the film was heated at 120°C. A dry film was obtained by drying. 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 conditions where the intensity measured at a wavelength of 365 nm was 100 mJ. In this way, a film with a photo-alignment film was prepared.

<Preparation of composition for forming polarizing film>
1. Comparative example 1
A polarizing film-forming composition (1) was obtained by mixing the following components and stirring at 80° C. for 1 hour. As the dichroic dye, an azo dye described in Examples of JP-A-2013-101328 was used.

（４－６）７５部

（４－８）２５部
・二色性色素：

２．５部

２．５部

２．５部
・重合開始剤：
２－ジメチルアミノ－２－ベンジル－１－（４－モルホリノフェニル）ブタン－１－オン（イルガキュア３６９；チバ・スペシャルティ・ケミカルズ(株)製） ６部
・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：
トルエン ４００部 ・Polymerizable liquid crystal compound (mixture):

(4-6) 75 copies

(4-8) 25 parts dichroic dye:

2.5 parts

2.5 parts

2.5 parts/Polymerization initiator:
2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369; manufactured by Ciba Specialty Chemicals Co., Ltd.) 6 parts Leveling agent:
Polyacrylate compound (BYK-361N; manufactured by BYK-Chemie) 1.2 parts/Solvent:
Toluene 400 parts

<Measurement of phase transition temperature>
(1) Formation of alignment film The phase transition temperature of the polymerizable liquid crystal compound in the polarizing film forming composition (1) was measured according to the following method. A 2% by mass aqueous solution of polyvinyl alcohol (Polyvinyl Alcohol 1000 fully saponified type, manufactured by Wako Pure Chemical Industries, Ltd.) was applied onto a glass substrate by a spin coating method, and after drying, a film with a thickness of 100 nm was formed. Subsequently, the surface of the obtained film was subjected to a rubbing treatment to form an alignment film. The rubbing process was performed using a semi-automatic rubbing device (product name: LQ-008 model, manufactured by Joyo Engineering Co., Ltd.) with a cloth (product name: YA-20-RW, manufactured by Yoshikawa Kako Co., Ltd.) with a pressing depth of 0.15 mm. The rotation speed was 500 rpm and 16.7 mm/s.

(2) Measurement of phase transition temperature By adding 75 parts by mass of polymerizable liquid crystal compound (4-6) and 25 parts by mass of polymerizable liquid crystal compound (4-8) to 400 parts by mass of chloroform and stirring at 80°C for 1 hour. A uniformly mixed mixed composition was obtained. The resulting composition was applied onto the glass substrate with the alignment film by spin coating, and the solvent chloroform was removed by heating and drying on a 130° C. hot plate for 3 minutes. Thereafter, the obtained coating film was quickly cooled to room temperature to obtain a dry film of the polymerizable liquid crystal compound. This dried film was heated again to 130°C on a hot plate, and then cooled down to 23°C at a rate of 5°C/min. The phase transition temperature was measured by observing with a polarizing microscope. As a result, a phase transition occurs to a nematic liquid crystal phase at 111.6°C, a phase transition to a smectic A phase at 109.2°C, a phase transition to a smectic B phase at 93.9°C, and a smectic B phase until the temperature reaches 23°C. confirmed that it would be maintained. In the above process, the isotropic phase transition temperature was confirmed to be 111.6°C.

<Method for manufacturing polarizing film>
(1) Formation of photo-alignment film A triacetyl cellulose film (KC8UX2M, manufactured by Konica Minolta, Inc.) is used as a base material, and after corona treatment is applied to the film surface, the above-mentioned composition for forming a photo-alignment film is applied. , and dried at 120° C. to obtain a dry film. This dried film was irradiated with polarized UV to form a photo-alignment film, thereby obtaining 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 conditions where the intensity measured at a wavelength of 365 nm was 100 mJ.

(2) Formation of polarizing film The composition for forming a polarizing film (1) was coated on the film with the photo-alignment film obtained above by bar coating method (#9 30 mm/s). The coated film was allowed to stand at room temperature of 23°C for 30 seconds, and then heated and dried for 1 minute in a drying oven at 120°C to sufficiently remove the solvent and phase the polymerizable liquid crystal compound into an isotropic liquid crystal phase. After the transition, the polymerizable liquid crystal compound was 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 with an exposure amount of 1000 mJ/cm ² (365 nm standard). Thereby, 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 (1) was formed from the dry film. The thickness of this polarizing film (1) was measured using a laser microscope (OLS3000 manufactured by Olympus Corporation) and was found to be 2.3 μm. What is thus obtained is a polarizer (polarizing film laminate) containing a polarizing film and a base material. As a result of similarly performing X-ray diffraction measurement on this polarizing film (1) using an X-ray diffraction device A sharp diffraction peak (Bragg peak) with a width (FWHM) of approximately 0.17° was obtained. Furthermore, similar results were obtained even when the incidence was perpendicular to the rubbing direction. The order period (d) determined from the peak position was approximately 4.4 Å, and it was confirmed that a structure reflecting a higher-order smectic phase was formed.

<Evaluation of missing dots>
When the polarizing film (1) thus obtained was observed through a microscope with a magnification of 200 times, circular color loss of approximately 200 to 800 μm was observed over the entire surface. In addition, when we observed the absorption axis (molecular orientation direction) of the polarizing film at 45° under a crossed nicol polarizing microscope with a magnification of 200 times, light leakage occurred, indicating that the polymerizable liquid crystal compound itself was oriented. was confirmed. From the above observation results, it was confirmed that there were regions (missing dots) in which the dichroic dye was not included in the liquid crystal domain.

<Dot dropout evaluation criteria>
◯: Not confirmed visually, nor confirmed by the above-mentioned microscopic observation.
Δ: Not visually confirmed, but confirmed in the above-mentioned microscopic observation.
×: Confirmed visually and also in the above-mentioned microscopic observation.

<Measurement of polarization degree Py and single transmittance Ty>
The degree of polarization Py and the single transmittance Ty of the polarizing film laminate of Comparative Example 1 were measured as follows. The transmittance in the transmission axis direction (Ta1) and the transmittance in the absorption axis direction (Tb2) in the wavelength range of 380 nm to 780 nm was measured using a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation) with a folder with a polarizer set. It was measured using the double beam method. A mesh that cuts the amount of light by 50% was installed on the reference side of the folder.

Using the following formulas (Formula 1) and (Formula 2), calculate the single transmittance and degree of polarization at each wavelength, and then perform visibility correction using the 2-degree field of view (C light source) of JIS Z 8701. Single transmittance (Ty) and visibility correction polarization degree (Py) were calculated. As a result, Ty=42.5% and Py=97.6%, indicating high performance derived from highly oriented smectic liquid crystals (this value corresponds to an absorption dichroism ratio of 48).
Single transmittance Ty (%) = (Ta1+Tb2)/2 (Formula 1)
Polarization degree Py (%) = (Ta1-Tb2)/(Ta1+Tb2)×100 (Formula 2)

2. Comparative Examples 2 to 5, Examples 1 to 16
Polarizing film forming compositions (2) to (21) were prepared in the same manner as in Comparative Example 1, except that the solvent was changed to the composition shown in Table 1, and polarizing films (2) to (21) were prepared in the same manner as in Comparative Example 1. 21) was prepared. Dot omission, degree of polarization Py, and single transmittance Ty of the obtained polarizing film were measured in the same manner as in Comparative Example 1. The evaluation results are shown in Table 2.

3. Example 17
A composition for forming a polarizing film (22) was prepared in the same manner as in Comparative Example 1, except that the polymerizable liquid crystal compound was changed to the following polymerizable liquid crystal compound, and a polarizing film (22) was prepared in the same manner as in Comparative Example 1. did. In addition, when the phase transition temperature of the polymerizable liquid crystal compound used in Example 17 was measured in the same manner as Comparative Example 1, it showed a phase transition to a nematic liquid crystal phase at 105.6°C, and a smectic A phase at 102.1°C. It was confirmed that the phase transition occurred at 85.4°C to the smectic B phase, and the smectic B phase was maintained until the temperature reached 23°C. In the above process, the isotropic phase transition temperature was confirmed to be 105.6°C. Dot omission, degree of polarization Py, and single transmittance Ty of the obtained polarizing film were measured in the same manner as in Comparative Example 1. The evaluation results are shown in Table 2.

（４－２２）７５重量部

（４－２５）２５重量部

(4-22) 75 parts by weight

(4-25) 25 parts by weight

4. Reference Example A composition for forming a polarizing film (23) was prepared in the same manner as in Comparative Example 1, except that the polymerizable liquid crystal compound was changed to Pario Color LC242 (manufactured by BASF), which is a nematic liquid crystal. A polarizing film (23) was prepared. Dot omission, degree of polarization Py, and single transmittance Ty of the obtained polarizing film were measured in the same manner as in Comparative Example 1. Note that the isotropic phase transition temperature of LC242 is 118.0°C. The evaluation results are shown in Table 2.

According to the present invention, the organic solvent A has a boiling point higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound by -20°C or more and 50°C or less, and the organic solvent A has a boiling point higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound by 50°C or more. It can be seen that the polarizing film formed from the composition for forming a polarizing film containing organic solvent B having a high boiling point has no dot dropout and has high polarizing performance.

Claims (12)

A polarizing film-forming composition comprising a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity, a dichroic dye, and at least two organic solvents,
The organic solvent has an organic solvent A having a boiling point higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound by -20°C or more and 50°C or less, and an organic solvent A having a boiling point higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound by 50°C or more. an organic solvent B having a boiling point higher than
The organic solvent A is a ketone solvent or an aromatic solvent,
The organic solvent B is selected from the group consisting of glycol solvents, amide solvents and γ-butyrolactone,
Forming a polarizing film, wherein the content of organic solvent A is 70 to 90 parts by mass and the content of organic solvent B is 10 to 30 parts by mass based on 100 parts by mass of the total organic solvents contained in the polarizing film forming composition. Composition for use. The boiling point of organic solvent A is 0°C or more and 50°C or less higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound, and the boiling point of organic solvent B is higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound by 50°C or more. The composition for forming a polarizing film according to claim 1, wherein the composition has a temperature of 150° C. or less. The composition for forming a polarizing film according to claim 1 or 2, further comprising a polymerization initiator. The composition for forming a polarizing film according to any one of claims 1 to 3, wherein the organic solvent B is selected from the group consisting of glycol solvents and amide solvents. The composition for forming a polarizing film according to any one of claims 1 to 4, wherein the solid content of the composition for forming a polarizing film is 5 to 40% by mass. The composition for forming a polarizing film according to claim 5, wherein the proportion of the polymerizable liquid crystal compound in the solid content is 40 to 99.9% by mass. The composition for forming a polarizing film according to claim 5 or 6, wherein the proportion of the dichroic dye in the solid content is 1 to 20% by mass. A polarizing film, which is a cured product of the composition for forming a polarizing film according to any one of claims 1 to 7, in which a polymerizable liquid crystal compound and/or a polymer thereof are oriented in a smectic liquid crystal state. The polarizing film according to claim 8, wherein a Bragg peak is obtained in X-ray diffraction measurement. A polarizing plate comprising the polarizing film according to claim 8 or 9, a base material, and an alignment film. Forming a coating film of the composition for forming a polarizing film according to any one of claims 1 to 7,
heating and drying the coating film to a temperature equal to or higher than the isotropic phase transition temperature of the polymerizable liquid crystal compound contained in the composition for forming a polarizing film, and then lowering the temperature to cause the polymerizable liquid crystal compound to undergo a phase transition to a smectic liquid crystal phase; ,
A method for producing a polarizing plate, comprising forming a polarizing film by polymerizing a polymerizable liquid crystal compound while maintaining the smectic liquid crystal phase. 12. The method for producing a polarizing plate according to claim 11, wherein a coating film of a composition for forming a polarizing film is formed on a photo-alignment film, the photo-alignment film comprising:
Forming a coating film from a composition containing a polymer or monomer and a solvent that generates an orientation regulating force when exposed to light;
Drying and removing the solvent from the coating film to obtain a dry coating film, and
irradiating the dried coating film with polarized ultraviolet light;
A method comprising: