Polymerizable liquid crystal composition, polarizing film, polarizing film, circular polarizer, and display device

Abstract

A polymerizable liquid crystal composition suitable for forming a polarizing film with excellent yellowing inhibition effect. A polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound, an organic dichroic pigment, and a sulfur-based antioxidant, wherein the polymerizable liquid crystal compound has at least one radical polymerizable group, and the sulfur-based antioxidant has an aromatic ring structure and a thiol structure or a thioether structure.

Description

Technology Field

[0001] The present invention relates to a polymerizable liquid crystal composition, a polarizing film comprising a cured film of the polymerizable liquid crystal composition, a polarizing film comprising the polarizing film, a circular polarizer, and a display device. Background Technology

[0002] Conventionally, polarizers are used in various image display panels, such as liquid crystal display panels or organic electroluminescence (organic EL) display panels, by being laminated to image display elements such as liquid crystal cells or organic EL display elements. Recently, there has been a continuous demand for thinning of displays such as image display panels, and new thinning is also required for polarizers and polarizers, which are components thereof. In response to this demand, for example, a thin coating-type polarizing film composed of a polymerizable liquid crystal compound and a compound exhibiting dichroism has been proposed (Patent Document 1). Prior art literature

[0003] Japanese Patent Publication No. 2019-008683 The problem to be solved

[0004] Recently, with the expansion of applications for thin polarizers, there is a demand for the development of polarizing films with improved light resistance. The inventors have discovered that a problem may arise in which the blue light emission of an organic light-emitting diode (OLED) is inhibited as the polarizing film yellows over time.

[0005] Therefore, the present invention aims to provide a polymerizable liquid crystal composition suitable for forming a polarizing film with excellent yellowing inhibition effect. means of solving the problem

[0006] The inventors, etc., have completed the present invention as a result of careful consideration to solve the above problem. That is, the present invention provides the following preferred embodiments.

[0007] [1] A polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound, an organic dichroic pigment and a sulfur-based antioxidant,

[0008] The above polymerizable liquid crystal compound has at least one radical polymerizable group, and

[0009] The above-mentioned sulfur-based antioxidant is a polymerizable liquid crystal composition having an aromatic ring structure and a thiol structure or a thioether structure.

[0010] [2] A polymerizable liquid crystal composition described in [1], wherein the sulfur-based antioxidant is at least one selected from the group consisting of a thiol compound having an aromatic ring, a sulfide compound having an aromatic ring, and a cyclic sulfide compound having an aromatic ring.

[0011] [3] A polymerizable liquid crystal composition described in [1] or [2] above, wherein the polymerizable liquid crystal compound is a liquid crystal compound exhibiting smectic liquid crystallization.

[0012] [4] A polymerizable liquid crystal composition described in any one of [1] to [3], wherein the organic dichroic pigment is an azo pigment.

[0013] [5] A polymerizable liquid crystal composition described in any one of [1] to [4], wherein the organic dichroic pigment has an aromatic ring structure.

[0014] [6] A polymerizable liquid crystal composition described in any one of [1] to [5], wherein the content of a sulfur-based antioxidant is 0.1 to 3 parts by mass per 100 parts by mass of the polymerizable liquid crystal compound.

[0015] [7] A polarizing film made of a cured film of a polymerizable liquid crystal composition described in any one of [1] to [6] above.

[0016] [8] A polarizing film described in [7] above that exhibits a Bragg peak in X-ray diffraction measurements.

[0017] [9] A polarizing film described in [7] or [8] above, having a film thickness in the range of 0.5 to 4 μm.

[0018]

[10] A polarizing film comprising a polarizing film and a transparent film as described in any one of [7] to [9] above.

[0019]

[11] A circular polarizer comprising a polarizing film and a phase difference film as described in any one of [7] to [9] above.

[0020]

[12] Phase difference film, Equations (1) and (2):

[0021] 100 ㎚ ≤ Re(550) ≤ 150 ㎚ (1)

[0022] Re(450) / Re(550) < 1 (2)

[0023] [In the equation, Re(λ) represents the frontal phase difference value for light of wavelength λ nm.]

[0024] A circular polarizer described in

[11] above that satisfies

[11] .

[0025]

[13] A display device comprising a polarizing film described in any one of [7] to [9] above, a polarizing film described in

[10] above, or a circular polarizing plate described in

[11] or

[12] above. Effects of the invention

[0026] According to the present invention, a polymerizable liquid crystal composition suitable for forming a polarizing film with excellent yellowing inhibition effect can be provided. Specific details for implementing the invention

[0027] Embodiments of the present invention will be described in detail below. Furthermore, the scope of the present invention is not limited to the embodiments described herein, and various modifications may be made within a scope that does not impede the spirit of the invention.

[0028] <Polymerizable Liquid Crystal Composition>

[0029] The polymerizable liquid crystal composition of the present invention comprises a polymerizable liquid crystal compound having at least one radical polymerizable group. The polymerizable liquid crystal compound is a compound having at least one radical polymerizable group and also having liquid crystal properties. The radical polymerizable group may be any functional group capable of causing a radical polymerization reaction, and examples include a group having a carbon-carbon unsaturated double bond, specifically a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, and the like. Among these, an acryloyloxy group, a methacryloyloxy group, and a vinyloxy group are preferred, an acryloyloxy group and a methacryloyloxy group are more preferred, and an acryloyloxy group is even more preferred.

[0030] In the present invention, it is preferable that the polymerizable liquid crystal compound is a liquid crystal compound exhibiting a smectic liquid crystal phase. By using a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase, a polarizing film with a high degree of orientation order can be formed. From the perspective of realizing a higher degree of orientation order, it is more preferable that the liquid crystal state exhibited by the polymerizable liquid crystal compound is a higher-order smectic phase (higher-order smectic liquid crystal state). Here, the higher-order smectic phase refers to the 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, and among these, the smectic B phase, smectic F phase, and smectic I phase are more preferable. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, but a thermotropic liquid crystal is preferred in that it allows for precise control of the film thickness. In addition, the polymerizable liquid crystal compound may be a monomer, an oligomer in which the polymerizable group is polymerized, or a polymer.

[0031] As for the polymerizable liquid crystal compound, any known polymerizable liquid crystal compound having at least one radical polymerizable group may be used, without being particularly limited. Examples of such polymerizable liquid crystal compounds include, for instance, a compound represented by the following formula (A) (hereinafter also referred to as "polymerizable liquid crystal compound (A)").

[0032] U 1 -V 1 -W 1 -(X 1 -Y 1 ) n -X 2 -W 2 -V 2 -U 2 (A)

[0033] [Among the formula (A),

[0034] X 1 and X 2 ...independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein the hydrogen atom included in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, a C1-4 alkyl group, a C1-4 fluoroalkyl group, a C1-4 alkoxy group, a cyano group, or a nitro group, and the carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom. provided that X 1 and X 2 At least one of them is a 1,4-phenylene group that may have a substituent or a cyclohexane-1,4-diyl group that may have a substituent.

[0035] Y 1 It is a single bond or a two-linked connector.

[0036] n is 1 to 3, and when n is 2 or greater, multiple X 1 They may be identical or different. X 2 is, multiple X 1It may be identical to any or all of the above, or different. Also, if n is 2 or greater, multiple Y 1 They may be identical or different. From the perspective of liquid crystallinity, n is preferably 2 or greater.

[0037] U 1 It represents a hydrogen atom or a polymerizable group.

[0038] U 2 represents a polymerizable group.

[0039] W 1 and W 2 It is a single coupling or a two-linkage connector, independently of each other.

[0040] V 1 and V 2 [ represents an alkanedyl group having 1 to 20 carbon atoms that may have substituents independently thereof, and the -CH2- constituting the alkanedyl group may be substituted with -O-, -CO-, -S-, or NH-.]

[0041] In a polymerizable liquid crystal compound (A), X 1 and X 2 is, independently of each other, preferably a 1,4-phenylene group that may have a substituent, or a cyclohexane-1,4-diyl group that may have a substituent, and X 1 and X 2 At least one of them is a 1,4-phenylene group that may have a substituent, or a cyclohexane-1,4-diyl group that may have a substituent, and is preferably a trans-cyclohexane-1,4-diyl group. Optional substituents for the 1,4-phenylene group that may have a substituent, or the cyclohexane-1,4-diyl group that may have a substituent, may include alkyl groups having 1 to 4 carbon atoms such as methyl, ethyl, and butyl groups, cyano groups, and halogen atoms such as chlorine and fluorine atoms. Preferably, it is unsubstituted.

[0042] In addition, the polymerizable liquid crystal compound (A) is, among Formula (A), Formula (A1):

[0043] -(X 1 -Y 1 ) n -X 2 - (A1)

[0044] [During the meal, X 1 , Y 1 , X 2 and n each represent the same meaning as above.

[0045] It is desirable that the part represented by (hereinafter also referred to as the part structure (A1)) has an asymmetric structure, as this makes it easy to exhibit smectic liquid crystallization.

[0046] As for the polymerizable liquid crystal compound (A) in which the substructure (A1) is an asymmetric structure, for example, n is 1 and 1 X 1 and X 2 Examples include polymerizable liquid crystal compounds having different structures. Also, n is 2 and 2 Y 1 As a compound with the same structure, 2 X 1 These have the same structure, and 1 X 2 These 2 X 1 Polymerizable liquid crystal compounds with a structure different from that of, 2 X 1 W in middle 1 X that binds to 1 This, the other party's X 1 and X 2 It has a different structure from and the other side's X 1 and X 2 Polymerizable liquid crystal compounds having the same structure as can also be cited. In addition, n is 3 and 3 Y 1 As a compound having the same structure, 3 X 1 and 1 X 2 Examples of polymerizable liquid crystal compounds in which any one of them has a structure different from all three others can be cited.

[0047] Y 1Silver, -CH2CH2-, -CH2O-, -CH2CH2O-, -COO-, -OCOO-, single bond, -N=N-, -CR a =CR b -, -C≡C-, -CR a =N- or -CO-NR a - is desirable. R a and R b represents, independently of each other, a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y 1 It is more preferable that it be -CH2CH2-, -COO-, or a single bond, and a plurality of Y 1 If this exists, X 2 Y combining with 1 It is more preferable that it be -CH2CH2- or -CH2O-. X 1 and X 2 In the case where all have the same structure, 2 or more Ys with different bonding methods 1 It is desirable for this to exist. Multiple Ys with different combination modes. 1 In the presence of this, smectic liquid crystallization tends to be easily expressed because it results in an asymmetric structure.

[0048] U 2 is a polymerizable group. U 1 It is silver, a hydrogen atom, or a polymerizable group, preferably a polymerizable group. U 1 and U 2 One of the groups is a radical polymerization group, and U 1 and U 2 It is desirable that all are polymerizable groups, and it is more desirable that all are radical polymerizable groups. As polymerizable groups, examples include those identical to the radical polymerizable groups previously exemplified as polymerizable groups possessed by polymerizable liquid crystal compounds. 1 The polymerizable group represented by and U 2 The polymerizable groups represented by may be different from each other, but it is preferable that they be of the same type, and U 1 and U 2It is preferable that at least one of them is a (meth)acryloyloxy group, and it is more preferable that both are (meth)acryloyl groups. In addition, the polymerizable group may be in a polymerized state or an unpolymerized state, but preferably in an unpolymerized state.

[0049] V 1 and V 2 Examples of alkanedyl groups represented by V include methylene groups, ethylene groups, propane-1,3-diyl groups, butane-1,3-diyl groups, butane-1,4-diyl groups, pentane-1,5-diyl groups, hexane-1,6-diyl groups, heptane-1,7-diyl groups, octane-1,8-diyl groups, decane-1,10-diyl groups, tetradecane-1,14-diyl groups, and icosan-1,20-diyl groups. 1 and V 2 The is preferably an alkanedyl group having 2 to 12 carbon atoms, and more preferably an alkanedyl group having 6 to 12 carbon atoms.

[0050] The alkandyl group may optionally have substituents such as cyano groups and halogen atoms, but the alkandyl group is preferably unsubstituted, and more preferably an unsubstituted straight-chain alkandyl group.

[0051] W 1 and W 2 In addition, independently, a single bond, -O-, -S-, -COO-, or -OCOO- is preferred, and a single bond or -O- is more preferred.

[0052] For a structure that is prone to exhibiting smectic liquid crystallization, it is preferable to have an asymmetric molecular structure among the molecular structures, and the polymerizable liquid crystal compound (A) is more preferably a polymerizable liquid crystal compound that exhibits smectic liquid crystallization, specifically having the partial structures (Aa) to (Ai) below. It is more preferable to have the partial structures (Aa), (Ab), or (Ac) from the perspective of being prone to exhibiting higher-order smectic liquid crystallization. In addition, in the following (Aa) to (Ai), * represents a bond loss (single bond).

[0053] [Chemical Formula 1]

[0054]

[0055] Examples of polymerizable liquid crystal compounds (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, it is preferable that the cyclohexane-1,4-diyl group be a trans group.

[0056] [Chemical Formula 2]

[0057]

[0058] [Chemical Formula 3]

[0059]

[0060] [Chemical Formula 4]

[0061]

[0062] Among these, at least one type selected from the group consisting of compounds represented by formulas (A-2), (A-3), (A-4), (A-5), (A-6), (A-7), (A-8), (A-13), (A-14), (A-15), (A-16) and (A-17) is preferred. As for the polymerizable liquid crystal compound (A), one type may be used alone, or two or more types may be used in combination.

[0063] The polymerizable liquid crystal compound (A) can be prepared by a known method described in, for example, Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), or Japanese Patent No. 4719156, etc.

[0064] The polymerizable liquid crystal composition of the present invention may include other polymerizable liquid crystal compounds other than the polymerizable liquid crystal compound (A), provided that such inclusion does not impede the effects of the present invention. From the perspective of obtaining a polarizing film with a high degree of orientation order, the ratio of the polymerizable liquid crystal compound (A) to the total mass of the prepolymerizable liquid crystal compounds in the polymerizable liquid crystal composition is preferably 51 mass% or more, more preferably 70 mass% or more, and even more preferably 90 mass% or more. By combining a plurality of polymerizable liquid crystal compounds, liquid crystal properties may be temporarily maintained even at temperatures below the liquid crystal-crystal phase transition temperature.

[0065] The content of the polymerizable liquid crystal compound in the polymerizable liquid crystal composition of the present invention is preferably 40 to 99.9 mass% with respect to the solid content of the polymerizable liquid crystal composition, more preferably 60 to 99 mass%, and even more preferably 70 to 99 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 increase.

[0066] In this specification, the term "solid content" refers to the total amount of components excluding volatile components, such as solvents, from a polymerizable liquid crystal composition.

[0067] The polymerizable liquid crystal composition of the present invention comprises an organic dichroic pigment. Here, an organic dichroic pigment refers to an organic pigment having a property in which the absorbance in the direction of the long axis of the molecule and the absorbance in the direction of the short axis are different. The organic dichroic pigments that can be used in the present invention are not particularly limited as long as they have the above properties, and may be dyes or pigments. Two or more types of dyes or pigments may be used in combination, or a dye and a pigment may be used in combination. Furthermore, the dichroic pigment may have polymerizable properties and liquid crystal properties.

[0068] As for organic dichroic pigments, the maximum absorption wavelength (λ) in the range of 300 to 700 nm MAX It is desirable to have ).

[0069] Examples of such organic dichroic pigments include acridin pigment, oxazine pigment, cyanine pigment, naphthalene pigment, azo pigment, and anthraquinone pigment.

[0070] Examples of azo dyes include monoazo dyes, bis-azo dyes, tris-azo dyes, tetrakis-azo dyes, and stilbenazo dyes, and bis-azo dyes and tris-azo dyes are preferred, and examples include the compound represented by formula (I) (hereinafter also referred to as “compound (I)”).

[0071] K 1 (-N=NK 2 ) p -N=NK 3 (I)

[0072] [Equation (I), K 1 and K 3 represents, independently, a phenyl group that may have substituents, a naphthyl group that may have substituents, a phenyl benzoate ester group that may have substituents, or a monovalent complex ring that may have substituents. K 2represents a p-phenylene group that may have substituents, a naphthalene-1,4-diyl group that may have substituents, a 4,4'-stilbenylene group that may have substituents, or a divalent complex ring that may have substituents. p represents an integer from 0 to 4. If p is an integer greater than or equal to 2, multiple K 2 They may be identical or different. In the range exhibiting absorption in the visible spectrum, -N=N- bonds may be substituted with -C=C-, -COO-, -NHCO-, or -N=CH- bonds.

[0073] Examples of monovalent complex ring groups include groups obtained by removing one hydrogen atom from complex ring compounds such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole. Examples of divalent complex ring groups include groups obtained by removing two hydrogen atoms from the above complex ring compounds.

[0074] K 1 and K 3 The phenyl group, naphthyl group, phenyl benzoate ester group and monovalent heterocyclic ring group in, and K 2The substituents optionally provided by the p-phenylene group, naphthalene-1,4-diyl group, 4,4'-stilbenylene group and the divalent complex ring in the above are: an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms having a polymerizable group, an alkenyl group having 1 to 4 carbon atoms; an alkoxy group having 1 to 20 carbon atoms having methoxy, ethoxy, butoxy, etc.; an alkoxy group having 1 to 20 carbon atoms having a polymerizable group; a fluoroalkyl group having 1 to 4 carbon atoms having a trifluoromethyl group, etc.; a cyano group; a nitro group; a halogen atom; Examples include substituted or unsubstituted amino groups such as amino groups, diethylamino groups, and pyrrolidino groups (a substituted amino group refers to an amino group having one or two alkyl groups having 1 to 6 carbon atoms, an amino group having one or two alkyl groups having 1 to 6 carbon atoms having a polymerizable group, or an amino group in which two substituted alkyl groups are bonded to each other to form an alkanedyl group having 2 to 8 carbon atoms. An unsubstituted amino group is -NH2). In addition, examples of the above polymerizable groups include (meth)acryloyl groups, (meth)acryloyloxy groups, etc.

[0075] Among the compounds (I), a compound represented by any of the following formulas (I-1) to (I-8) is preferred.

[0076] [Chemical Formula 5]

[0077]

[0078] [Among Equations (I-1) to (I-8),

[0079] B 1 ~ B 30 Each represents, independently, a hydrogen atom, a C1-6 alkyl group, a C1-6 alkenyl group, a C1-4 alkoxy group, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of substituted amino groups and unsubstituted amino groups are as above), a chlorine atom, or a trifluoromethyl group.

[0080] n1 to n4 represent integers from 0 to 3 independently of each other.

[0081] If n1 is 2 or more, multiple B 2 They may be identical or different from each other,

[0082] If n2 is 2 or more, multiple B 6 They may be identical or different from each other,

[0083] If n3 is 2 or more, multiple B 9 They may be identical or different from each other,

[0084] If n4 is 2 or more, multiple B 14 They may be identical or different.

[0085] As the above anthraquinone pigment, a compound represented by formula (I-9) is preferred.

[0086] [Chemical Formula 6]

[0087]

[0088] [In food (I-9),

[0089] R 1 ~ R 8 Silver, independently, hydrogen atoms, -R x , -NH2, -NHR x , -NR x 2, -SR x or represents a halogen atom.

[0090] R x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0091] As the above oxazine pigment, a compound represented by formula (I-10) is preferred.

[0092] [Chemical Formula 7]

[0093]

[0094] [In the food (I-10),

[0095] R9 ~ R 15 is, independently of each other, hydrogen atoms, -R x , -NH2, -NHR x , -NR x 2, -SR x or represents a halogen atom.

[0096] R x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0097] As the acridine pigment mentioned above, a compound represented by formula (I-11) is preferred.

[0098] [Chemical Formula 8]

[0099]

[0100] [In the (I-11) formula,

[0101] R 16 ~ R 23 Silver, independently, hydrogen atoms, -R x , -NH2, -NHR x , -NR x 2, -SR x or represents a halogen atom.

[0102] R x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0103] In Equations (I-9), (I-10), and (I-11), R x Examples of alkyl groups having 1 to 6 carbon atoms include methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, and hexyl groups, and examples of aryl groups having 6 to 12 carbon atoms include phenyl groups, toluyl groups, xylyl groups, and naphthyl groups.

[0104] As the above cyanine pigment, the compound represented by formula (I-12) and the compound represented by formula (I-13) are preferred.

[0105] [Chemical Formula 9]

[0106]

[0107] [In the food (I-12),

[0108] D 1 and D 2 represents a group that is independently represented by any of equations (I-12a) to (I-12d).

[0109] [Chemical Formula 10]

[0110]

[0111] n5 represents an integer from 1 to 3.

[0112] [Chemical Formula 11]

[0113]

[0114] [In the food (I-13),

[0115] D 3 and D 4 represents a group that is independently represented by any of equations (I-13a) to (1-13h).

[0116] [Chemical Formula 12]

[0117]

[0118] n6 represents an integer from 1 to 3.

[0119] The weight average molecular weight of the organic dichroic pigment is typically 300 to 2000, and preferably 400 to 1000.

[0120] Since the polymerizable liquid crystal composition of the present invention has an excellent effect of suppressing the photodegradation of dichroic pigments in a polarizing film when a polarizing film is formed, the effects of the present invention can be particularly pronounced when using organic dichroic pigments that are susceptible to photodegradation and are sensitive to light such as ultraviolet rays in sunlight. Therefore, the polymerizable liquid crystal composition of the present invention is particularly advantageous when using organic dichroic pigments that are susceptible to photodegradation.

[0121] Among the above organic dichroic pigments, azo pigments are desirable for the production of polarizing films with excellent polarization performance because they have high linearity. Accordingly, in one embodiment of the present invention, the organic dichroic pigment included in the polymerizable liquid crystal composition is preferably an azo pigment.

[0122] In addition, regarding the relationship with the sulfur-based antioxidant described below, it is preferable that the organic dichroic pigment has an aromatic ring structure. In one embodiment of the present invention, it is more preferable that the polymerizable liquid crystal composition is an azo pigment having an aromatic ring structure as the organic dichroic pigment.

[0123] The content of the organic dichroic pigment in the polymerizable liquid crystal composition of the present invention can be appropriately determined according to the type of organic dichroic pigment used, but is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.1 to 12 parts by mass per 100 parts by mass of the polymerizable liquid crystal compound. If the content of the organic dichroic pigment is within the above range, it is difficult to disrupt the orientation of the polymerizable liquid crystal compound, and a polarizing film having a high degree of orientation order can be obtained.

[0124] The polymerizable liquid crystal composition of the present invention comprises, as a sulfur-based antioxidant, a sulfur-based antioxidant having an aromatic ring structure and a thiol structure or a thioether structure. The sulfur-based antioxidant functions as a so-called secondary antioxidant and has the effect of decomposing peroxides generated from radicals by light irradiation. By including a sulfur-based antioxidant, the polymerizable liquid crystal composition of the present invention can exhibit a high inhibitory effect against time-dependent yellowing in the polarizing film obtained.

[0125] The mechanism by which a polarizing film with excellent yellowing inhibition effect can be obtained from the polymerizable liquid crystal composition of the present invention is inferred as follows. That is, in the polymerizable liquid crystal composition, the sulfur-based antioxidant having an aromatic ring structure can exist in a more cooperatively mixed state in the liquid crystal state composed of the polymerizable liquid crystal compound and the organic dichroic pigment, thereby bringing the intermolecular distance with the organic dichroic pigment closer. For this reason, the sulfur-based antioxidant acts more easily as an antioxidant and not only inhibits the photodegradation of the organic dichroic pigment but can also exert a radical decomposition function that occurs over time within the liquid crystal cured film over a long period. The above mechanism is inferred from the fact that a polarizing film with an excellent yellowing inhibition effect can be obtained when the organic dichroic pigment has an aromatic ring structure in the present invention. In addition, generally, a polarizing film with excellent polarization performance can be obtained by cooperatively aligning an organic dichroic pigment with a highly ordered polymerizable liquid crystal compound. When a sulfur-based antioxidant is structurally similar to an organic dichroic pigment, it becomes possible to introduce the sulfur-based antioxidant into the liquid crystal without disrupting the cooperative orientation of the polymerizable liquid crystal compound and the organic dichroic pigment. Consequently, since the photodegradation suppression effect of the organic dichroic pigment can be expected while maintaining the high orientation order of the polymerizable liquid crystal compound and the organic dichroic pigment, a polarizing film with excellent polarization performance can be obtained.

[0126] Therefore, when the polymerizable liquid crystal composition comprises a compound having an aromatic ring structure as an organic dichroic pigment, for example, an organic dichroic pigment having an aromatic ring structure as previously exemplified, a particularly more remarkable effect of the present invention can be expected.

[0127] A sulfur-based antioxidant having an aromatic ring structure and a thiol structure or a thioether structure (hereinafter also referred to as "sulfur-based antioxidant (S)") is not particularly limited as long as it has an aromatic ring structure and a thiol structure or a thioether structure. One type of sulfur-based antioxidant (S) may be used alone, or two or more types may be used in combination.

[0128] Examples of aromatic ring structures included in the sulfur-based antioxidant (S) include aromatic hydrocarbon rings and complex aromatic rings. These aromatic ring structures may each be monocyclic or condensed ring structures. The aromatic ring structure is preferably a complex aromatic ring, more preferably a complex aromatic ring having at least one of nitrogen, sulfur, and oxygen, and even more preferably a complex aromatic ring having at least one of nitrogen and sulfur. When the aromatic ring structure is a condensed ring structure, it may be a condensed ring consisting of two rings or a condensed ring consisting of three or more rings. Examples of aromatic ring structures include benzene rings, naphthalene rings, quinoline rings, thiazole rings, benzothiazole rings, thienothiazole rings, imidazole rings, benzimidazole rings, oxazole rings, benzoxazole rings, etc. Hydrogen atoms included in the above aromatic rings may be substituted. Examples of substituents include halogen atoms, alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, cyano groups, and nitro groups.

[0129] In terms of light resistance and yellowing inhibition effects, and high polarization characteristics, it is preferable to include at least one selected from the group consisting of thiol compounds having an aromatic ring, sulfide compounds having an aromatic ring, and cyclic sulfide compounds having an aromatic ring as a sulfur-based antioxidant (S).

[0130] Examples of sulfur-based antioxidants (S) include compounds having a structure represented by formula (S1) or compounds having a structure represented by formula (S2).

[0131] [Chemical Formula 13]

[0132]

[0133] In formula (S1), m is 1 or 2, and preferably 1.

[0134] In formula (S1), X is -N- or -CH-, and Y is -NH-, -N(Me)- [Me means methyl group], -S-, -O-, -C(=O)-, -CH2- or -CH=CH-. It is preferable that at least one of X and Y comprises at least one of the heteroatoms described above, more preferable that X and Y each comprise the heteroatoms described above, and even more preferable that X is -N- and Y is -NH-.

[0135] In formula (S1), R1 is a hydrogen atom or a branched or unbranched alkyl group having 1 to 12 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom.

[0136] In formula (S1), R2 to R5 are each independently a hydrogen atom, -OH, -NH2, a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or a branched or unbranched thioalkyl group having 1 to 12 carbon atoms. It is preferable that R2, R4, and R5 are all hydrogen atoms, and R3 is a hydrogen atom, -OH, -NH2, a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or a branched or unbranched thioalkyl group having 1 to 12 carbon atoms, and it is more preferable that R2 to R5 are all hydrogen atoms.

[0137] In formula (S2), n is 1 or 2, and preferably 1.

[0138] The two benzene rings in formula (S2) may be joined via a linker Z. In formula (S2), --Z-- indicates that the linker Z is any bond. Examples of linker Z include a single bond, -NH-, -N(Me)- [Me means a methyl group], -S-, -O-, -C(=O)-, -CH2-, etc. When the two benzene rings are not joined via a linker Z, the unlinked sites are each independently a hydrogen atom, -NH2, -OH, -NO2, a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or a branched or unbranched thioalkyl group having 1 to 12 carbon atoms.

[0139] In formula (S2), it is preferable that the two benzene rings are joined by an interlinker Z, more preferable that the interlinker Z is -NH-, -N(Me)-, -S- or -O-, and even more preferable that the interlinker Z is -NH- or -N(Me)-.

[0140] In equation (S2), R6 to R 13 Each is independently a hydrogen atom, -OH, -NH2, a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or a branched or unbranched thioalkyl group having 1 to 12 carbon atoms.

[0141] If connector Z is -NH-, R6, R8~ R 11 and R 13 All of them are hydrogen atoms, and R 7 and R 12a. Preferably, each independently is a hydrogen atom, -OH, -NH2, a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or a branched or unbranched thioalkyl group having 1 to 12 carbon atoms, and R7 It is more desirable that it be a hydrogen atom.

[0142] If connector Z is -N(Me)-, R6, R8~ R 11 and R 13 All of them are hydrogen atoms, and R7 and R 12 a. Preferably, each independently is a hydrogen atom, -OH, -NH2, a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or a branched or unbranched thioalkyl group having 1 to 12 carbon atoms, and R7 It is more preferable that it is also a hydrogen atom, and R6~R 13 It is more desirable that all of them are hydrogen atoms.

[0143] Examples of thiol compounds having an aromatic ring, sulfide compounds having an aromatic ring, and cyclic sulfide compounds having an aromatic ring include, for instance, the following compounds.

[0144] [Chemical Formula 14]

[0145]

[0146] The weight average molecular weight of the sulfur-based antioxidant (S) is preferably 600 or less, more preferably 400 or less, and even more preferably 250 or less. If the polymerization average molecular weight is below the upper limit, it becomes easier to orient within the liquid crystal molecules without disturbing the orientation of the polymerizable liquid crystal compound, and since it can exist near the organic dichroic pigment, the photodegradation suppression effect of the organic dichroic pigment and the yellowing suppression effect of the polarizing film can be further improved. The weight average molecular weight of the sulfur antioxidant (S) is not particularly limited, but is typically 50 or more, and preferably 100 or more.

[0147] Among these, sulfur-based antioxidants with low steric hindrance and high linearity in their molecular structure are preferred because they are easy to align with polymerizable liquid crystal compounds and tend to have excellent effects in inhibiting photodegradation of organic dichroic pigments and inhibiting yellowing of polarizing films. As for the sulfur-based antioxidant (S) in the present invention, although not limited to the above, sulfur compounds having a benzimidazole ring such as 2-mercaptobenzimidazole; thiophenothiazines having substituents such as 10-methylphenothiazine, 2-methoxyphenothiazine, and 2-ethylthiophenothiazine are preferred.

[0148] The content of the sulfur-based antioxidant (S) is preferably 0.1 to 3 parts by mass per 100 parts by mass of the polymerizable liquid crystal compound, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, even more preferably 2.5 parts by mass or less, and even more preferably 2 parts by mass or less. If the content of the sulfur-based antioxidant (S) is greater than or equal to the lower limit value above, photodegradation of the organic dichroic pigment and yellowing of the resulting polarizing film can be effectively suppressed. In addition, if the content of the sulfur-based antioxidant (S) is less than or equal to the upper limit value above, it is difficult to disrupt the orientation of the polymerizable liquid crystal compound, and a high suppression effect against photodegradation of the organic dichroic pigment and yellowing of the resulting polarizing film can be expected.

[0149] The polymerizable liquid crystal composition may include an antioxidant other than a sulfur-based antioxidant (S).

[0150] Antioxidants other than sulfur-based antioxidants (S) include, for example, secondary antioxidants such as sulfur-based antioxidants that do not have an aromatic ring structure and phosphorus-based antioxidants, as well as primary antioxidants such as phenol-based antioxidants or amine-based antioxidants that have the function of capturing the generated radicals.

[0151] When a polymerizable liquid crystal composition includes an antioxidant other than a sulfur-based antioxidant (S), in order to maintain a high orientation order of the polymerizable liquid crystal compound and exhibit a sufficiently high yellowing inhibition effect, it is preferable that the content of the sulfur-based antioxidant (S) be 50 mass% or more and 70 mass% or more with respect to the total amount of all antioxidants included in the polymerizable liquid crystal composition.

[0152] The polymerizable liquid crystal composition of the present invention may additionally include a polymerization initiator.

[0153] A polymerization initiator is a compound capable of initiating a polymerization reaction of a polymerizable liquid crystal compound, and a photopolymerization initiator is preferred in that it can initiate a polymerization reaction under lower temperature conditions. Specifically, a photopolymerization initiator capable of generating active radicals or acids by the action of light can be cited, and among these, a photopolymerization initiator that generates radicals by the action of light is preferred. The polymerization initiator can be used alone or in combination of two or more types.

[0154] Examples of polymerization initiators include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodine salts, and sulfonium salts.

[0155] Examples of benzoin compounds include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

[0156] Examples of benzophenone compounds include benzophenone, o-methyl benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and 2,4,6-trimethylbenzophenone.

[0157] Examples of alkylphenone compounds include diethoxyacetophenone, 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-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 oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one.

[0158] Examples of acylphosphine oxide compounds include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

[0159] Triazine compounds include 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, and 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine. Examples include 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine.

[0160] Commercially available polymerization initiators may be used. Examples of commercially available polymerization initiators include "Irgacure (Trademark) 907", "Irgacure (Trademark) 184", "Irgacure (Trademark) 651", "Irgacure (Trademark) 819", "Irgacure (Trademark) 250", "Irgacure (Trademark) 369" (Chiba Japan Corp.); "Sakeall (Trademark) BZ", "Sakeall (Trademark) Z", "Sakeall (Trademark) BEE" (Seiko Chemical Corp.); "Kayacure (Trademark) BP100" (Nippon Kagaku Corp.); Examples include "Kaya Cure (registered trademark) UVI-6992" (manufactured by Dow Corporation); "Adeka Optomer SP-152", "Adeka Optomer SP-170" (ADEKA Corporation); "TAZ-A", "TAZ-PP" (Nippon Seibelhegna Co., Ltd.); and "TAZ-104" (Sanwa Chemical Co., Ltd.).

[0161] When a polymerizable liquid crystal composition includes a polymerization initiator, the content thereof can be appropriately determined according to the type and amount of the polymerizable liquid crystal compound included in the polymerizable liquid crystal composition. For every 100 parts by mass of the polymerizable liquid crystal compound, 0.1 to 30 parts by mass is preferred, 0.5 to 10 parts by mass is more preferred, and 0.5 to 8 parts by mass is even more preferred. If 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.

[0162] If the polymerizable liquid crystal composition includes a photopolymerization initiator, it may additionally include a photosensitizer. By using a photosensitizer, the polymerization reaction of the polymerizable liquid crystal compound can be further promoted.

[0163] Examples of photosensitizers include xanthone compounds such as xanthones and thioxanthones (2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and alkoxy-containing anthracene (dibutoxycyanthracene, etc.); phenothiazines and rubrene, etc. Photosensitizers may be used alone or in combination of two or more types.

[0164] The content of the photosensitizer in the polymerizable liquid crystal composition of the present invention can be appropriately determined according to the type and amount of the photopolymerization initiator and the polymerizable liquid crystal compound, wherein 0.1 to 30 parts by mass is preferred, 0.5 to 10 parts by mass is more preferred, and 0.5 to 8 parts by mass is even more preferred per 100 parts by mass of the polymerizable liquid crystal compound.

[0165] The polymerizable liquid crystal composition of the present invention may additionally include 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 flatter; specifically, a surfactant may be used. As for the leveling agent, at least one selected from the group consisting of a leveling agent having a polyacrylate compound as a main component and a leveling agent having a fluorine atom-containing compound as a main component is preferred.

[0166] Leveling agents can be used alone or in combination of two or more types.

[0167] Examples of leveling agents with polyacrylate compounds as the main component include “BYK-350”, “BYK-352”, “BYK-353”, “BYK-354”, “BYK-355”, “BYK-358N”, “BYK-361N”, “BYK-380”, “BYK-381”, and “BYK-392” (BYK Chemie).

[0168] Leveling agents with fluorine atom-containing compounds as the main component include "Megapac (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 Inc.); "Surfron (registered trademark) S-381", "S-382", "S-383", "S-393", "SC-101", "SC-105", "KH-40", and "SA-100" (AGC Seimi Chemical Co., Ltd.); Examples include "E1830", "E5844" (Daikin Fine Chemical Research Institute, Inc.); "F-Top EF301", "F-Top EF303", "F-Top EF351" and "F-Top EF352" (Mitsubishi Material Electronics Chemical Co., Ltd.).

[0169] The content of the leveling agent in the polymerizable liquid crystal composition of the present invention is preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the polymerizable liquid crystal compound, and more preferably 0.05 to 3 parts by mass.

[0170] If the content of the leveling agent is within the above range, it is easy to horizontally orient the polymerizable liquid crystal compound, and also, non-uniformity is less likely to occur, so a smoother polarizing film can be obtained.

[0171] The polymerizable liquid crystal composition of the present invention may additionally include other additives other than polymerization initiators, photosensitizers, and leveling agents. Examples of other additives include release agents, stabilizers, coloring agents such as bluening agents, flame retardants, and lubricants. When the polymerizable liquid crystal composition includes other additives, the content of the other additives is preferably greater than 0% and less than or equal to 20 mass% with respect to the solid content of the polymerizable liquid crystal composition, and more preferably greater than 0% and less than or equal to 10 mass%.

[0172] The polymerizable liquid crystal composition of the present invention may additionally include a solvent. For example, since compounds that generally exhibit smectic liquid crystallization have high viscosity, adding a solvent to the polymerizable liquid crystal composition facilitates coating, and consequently, often facilitates the formation of a polarizing film. The solvent can be appropriately selected according to the solubility of the polymerizable liquid crystal compound and the organic dichroic pigment, and may include, for example, alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, ethyl lactate; and ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, methyl isobutyl ketone. Examples include 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 chlorinated hydrocarbon solvents such as chloroform and chlorobenzene.

[0173] The solvents used may be used alone or in combination of two or more types. The content of the solvent is preferably 100 to 1900 parts by mass, more preferably 150 to 900 parts by mass, and even more preferably 180 to 600 parts by mass, based on 100 parts by mass of the solid component constituting the polymerizable liquid crystal composition.

[0174] The polymerizable liquid crystal composition of the present invention can typically be prepared by mixing and stirring a polymerizable liquid crystal compound, an organic dichroic pigment and a sulfur-based antioxidant, and, if necessary, the additives and solvents described above.

[0175] The polymerizable liquid crystal composition of the present invention can preferably be used in the manufacture of polarizing films because it is possible to obtain a liquid crystal cured film that is resistant to yellowing over time. Accordingly, the present invention relates to a polarizing film formed from a cured film of the polymerizable liquid crystal composition of the present invention.

[0176] A polarizing film with a high degree of orientation order can be manufactured using the polymerizable liquid crystal composition of the present invention.

[0177] In polarizing films with a high degree of orientation order, Bragg peaks derived from higher-order structures, such as hexatic or crystal phases, are obtained in X-ray diffraction measurements.

[0178] A Bragg peak refers to a peak originating from a plane-periodic structure of molecular orientation. Accordingly, in a polarizing film formed from the polymerizable liquid crystal composition of the present invention, it is preferable that the polymerizable liquid crystal compound or its polymer be oriented such that the polarizing film exhibits a Bragg peak in X-ray diffraction measurements, and it is more preferable that the molecules of the polymerizable liquid crystal compound be oriented in a "horizontal orientation" that absorbs light. In the present invention, a polarizing film having a plane-periodic spacing of molecular orientation of 3.0 to 6.0 Å is preferred. A high degree of orientation order, such as exhibiting a Bragg peak, can be achieved by controlling the type of polymerizable liquid crystal compound used, the type and amount of antioxidant, the type and amount of organic dichroic pigment, etc.

[0179] The polarizing film of the present invention is, for example, formed by a coating film of the polymerizable liquid crystal composition of the present invention.

[0180] Removing the solvent from the above film,

[0181] Raising the temperature above the temperature at which a polymerizable liquid crystal compound transitions to a liquid phase, then lowering the temperature, and causing the polymerizable liquid crystal compound to transition to a liquid crystal phase (smectic liquid crystal state), and

[0182] Polymerizing a polymerizable liquid crystal compound while maintaining the above liquid crystal phase (smectic liquid crystal state).

[0183] It can be manufactured by a method including.

[0184] The formation of a film of a polymerizable liquid crystal composition can be carried out by applying a polymerizable liquid crystal composition, in particular, a polymerizable liquid crystal composition (hereinafter also referred to as a "composition for forming a polarizing film") to a substrate or an alignment film described later, etc., in which the viscosity is adjusted by adding a solvent. The polymerizable liquid crystal composition may also be applied directly onto a phase difference film or other layers constituting the polarizing plate of the present invention.

[0185] The substrate is typically a transparent substrate. When the substrate is not installed on the display surface of a display element, for example, when a laminate from which the substrate has been removed from a polarizing film is installed on the display surface of a display element, the substrate does not need to be transparent. A transparent substrate refers to a substrate having transparency capable of transmitting light, particularly visible light, and transparency refers to a characteristic in which the transmittance for light rays with wavelengths ranging from 380 to 780 nm is 80% or more. Specific examples of transparent substrates include light-transmitting resin substrates. Resins constituting the light-transmitting resin substrate include polyolefins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene-based polymers; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid esters; polyacrylic acid esters; cellulose esters such as triacetylcellulose, diacetylcellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; and polysulfone. Examples include polyethersulfone; polyetherketone; polyphenylene sulfide and polyphenylene oxide. In terms of availability and transparency, polyethylene terephthalate, polymethacrylic acid ester, cellulose ester, cyclic olefin resin, or polycarbonate are preferred. Cellulose ester is a material in which some or all of the hydroxyl groups contained in cellulose are esterified, and it is readily available in the market. In addition, cellulose ester substrates are also readily available in the market. Examples of commercially available cellulose ester substrates include "Fujitac Film" (Fuji Photo Film Co., Ltd.); "KC8UX2M", "KC8UY", and "KC4UY" (Konica Minolta Opto Co., Ltd.).

[0186] The characteristics required for the substrate vary depending on the composition of the polarizing film, but generally, a substrate with as little phase difference as possible is preferred. Examples of substrates with as little phase difference as possible include cellulose ester films that do not have a phase difference, such as Zero Tack (Konica Minolta Opto Corp.) and Z Tack (Fujifilm Corp.). An unoriented cyclic olefin resin substrate is also preferred. On the surface of the substrate where the polarizing film is not laminated, a hard coating treatment, an anti-reflective treatment, an antistatic treatment, etc. may be applied.

[0187] The thickness of the substrate is typically 5 to 300 μm, preferably 20 to 200 μm, and more preferably 20 to 100 μm, because if it is too thin, the strength decreases and processability tends to decline.

[0188] Known methods for applying a polarizing film-forming composition to a substrate, etc. include spin coating, extrusion, gravure coating, die coating, bar coating, applicator coating, and printing methods such as flexographic methods.

[0189] Next, a dried film is formed by removing the solvent by drying, etc., under conditions where the polymerizable liquid crystal compound included in the film obtained from the composition for forming a polarizing film does not polymerize. Examples of drying methods include natural drying, ventilation drying, heat drying, and reduced pressure drying.

[0190] In addition, to phase transition the polymerizable liquid crystal compound into a liquid phase, the temperature is raised above the temperature at which the polymerizable liquid crystal compound transitions into a liquid phase, and then lowered, thereby phase transitioning the polymerizable liquid crystal compound into a liquid phase (smectic liquid crystal state). This phase transition may be carried out after the removal of the solvent from the coating film, or simultaneously with the removal of the solvent.

[0191] By polymerizing a polymerizable liquid crystal compound while maintaining its liquid crystal phase (smectic liquid crystal state), a cured film of the polymerizable liquid crystal composition is formed as a polarizing film. Photopolymerization is preferred as the polymerization method. In photopolymerization, the light irradiated onto the dried film is appropriately selected according to the type of photopolymerization initiator included in the dried film, the type of polymerizable liquid crystal compound (in particular, the type of polymerizable group possessed by the polymerizable liquid crystal compound), and the amount thereof. 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, or active electron beams. Among these, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and allows the use of photopolymerization devices that are widely used in the field. It is also desirable to select the type of polymerizable liquid crystal compound or photopolymerization initiator included in the polymerizable liquid crystal composition so that photopolymerization is possible by ultraviolet light. In addition, the polymerization temperature can be controlled by irradiating light while cooling the dried film with an appropriate cooling means during polymerization. By employing such a cooling means, polymerization of the polymerizable liquid crystal compound can be carried out at a lower temperature, allowing a polarizing film to be formed appropriately even if a substrate with relatively low heat resistance is used. A patterned polarizing film can also be obtained by performing masking or development during photopolymerization.

[0192] Examples of light sources for the above active energy lines include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting light in a wavelength range of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, etc.

[0193] The ultraviolet irradiation intensity is typically 10 to 3,000 mW / cm². The ultraviolet irradiation intensity is preferably an intensity in a wavelength range effective for activating the photopolymerization initiator. The time for irradiating light is typically 0.1 seconds to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and even more preferably 10 seconds to 1 minute. When irradiated once or multiple times with such ultraviolet irradiation intensity, the accumulated light amount is 10 to 3,000 mJ / cm², preferably 50 to 2,000 mJ / cm², and more preferably 100 to 1,000 mJ / cm².

[0194] By performing photopolymerization, the polymerizable liquid crystal compound is polymerized while maintaining a liquid crystal state, preferably a smectic phase, and more preferably a higher-order smectic phase, to form a polarizing film. The polarizing film obtained by polymerizing the polymerizable liquid crystal compound while maintaining a smectic phase liquid crystal state has the advantage of having high polarization performance compared to a conventional host-guest type polarizing film, that is, a polarizing film formed in a nematic phase liquid crystal state, in conjunction with the action of the dichroic dye. In addition, it has the advantage of having excellent strength compared to a film coated only with a dichroic dye or a lyotropic liquid crystal.

[0195] The thickness of the polarizing film can be appropriately selected depending on the applied display device, preferably 0.5 to 4 μm, more preferably 0.5 to 3 μm.

[0196] It is preferable that the polarizing film be formed on the alignment film. The alignment film has an orientation regulating power that aligns the polymerizable liquid crystal compound in a desired direction. The alignment film preferably has solvent resistance so as not to dissolve upon application of a composition containing the polymerizable liquid crystal compound, and also has heat resistance during the removal of the solvent or heat treatment for the orientation of the polymerizable liquid crystal compound. Examples of such alignment films include an alignment film containing an oriented polymer, a photoalignment film, a groove alignment film having an uneven pattern or multiple grooves on its surface, and a stretched film stretched in the orientation direction; however, from the perspective of the precision of the alignment angle and quality, a photoalignment film is preferred.

[0197] Examples of oriented polymers include polyamides or gelatins having amide bonds within the molecule, polyimides having imide bonds within the molecule and their hydrolysates such as polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid esters. Among these, polyvinyl alcohol is preferred.

[0198] Orientation polymers can be used alone or in combination of two or more types.

[0199] An orientation film comprising an orientation polymer is typically obtained by applying a composition in which the orientation polymer is dissolved in a solvent (hereinafter referred to as an "orientation polymer composition") to a substrate and removing the solvent, or by applying the orientation polymer composition to a substrate, removing the solvent, and rubbing (rubbing method). As for the solvent, the same as the solvent previously exemplified as a solvent that can be used when forming a polarizing film may be cited.

[0200] The concentration of the oriented polymer in the oriented polymer composition may be within a range where the oriented polymer material can be completely dissolved in a solvent, and is preferably 0.1 to 20% in terms of solid content relative to the solution, and more preferably about 0.1 to 10%.

[0201] As an oriented polymer composition, commercially available alignment film materials may be used as is. Examples of commercially available alignment film materials include SunEver (registered trademark, manufactured by Nissan Chemical Industry Co., Ltd.) and Optomer (registered trademark, manufactured by JSR Corporation).

[0202] A method for applying an oriented polymer composition to a substrate can be the same as the method exemplified for applying a polarizing film-forming composition to a substrate.

[0203] Methods for removing solvents included in an oriented polymer composition include natural drying, ventilation drying, heat drying, and vacuum drying.

[0204] In order to impart orientation regulatory force to the orientation film, rubbing treatment may be performed as needed (rubbing method).

[0205] A method for imparting orientation control force by a rubbing method includes a method in which an orientation polymer composition is applied to a substrate and annealed to a rubbing roll that is wound and rotating, thereby bringing the film of the orientation polymer formed on the surface of the substrate into contact with the substrate.

[0206] A photoalignment film is typically obtained by applying a composition (hereinafter also referred to as a "composition for forming a photoalignment film") comprising a polymer or monomer having a photoreactive group and a solvent to a substrate and irradiating polarized light (preferably polarized UV). The photoalignment film is more preferable in that the direction of the orientation regulating force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

[0207] A photoreactive group refers to a group that generates liquid crystal orientation ability upon light irradiation. Specifically, it may include a group involved in photoreactions that are the origin of liquid crystal orientation ability, such as molecular orientation induction, isomerization, dimerization, photocrosslinking, or photodecomposition reactions, which are caused by light irradiation. Among these, a group involved in dimerization or photocrosslinking is preferred in that it exhibits excellent orientation. As a photoreactive group, a group having an unsaturated bond, particularly a double bond, is preferred, and a group having at least one selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond), and a carbon-oxygen double bond (C=O bond) is particularly preferred.

[0208] Examples of photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazole groups, stilbazolium groups, chalcone groups, and cinnamoyl groups.

[0209] Examples of photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bis-azo groups, forma groups, and groups having azoxybenzene structures. Examples of photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, 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 alkyl halide groups.

[0210] Among these, photoreactive groups involved in photodimerization reactions are preferred, and cinnamoyl groups and chalcone groups are preferred in that the amount of polarized light irradiation required for photoorientation is relatively small, and it is easy to obtain a photoorientation film with excellent thermal stability and stability over time. As for the polymer having photoreactive groups, it is particularly preferred that the terminal portion of the polymer side chain has a cinnamoyl group having a cinnamyl structure.

[0211] By applying a composition for forming a photo-alignment film onto a substrate, a photo-alignment-inducing layer can be formed on the substrate. As for the solvent included in the composition, the same as the solvent previously exemplified as a solvent that can be used when forming a polarizing film may be cited, and it can be appropriately selected depending on the solubility of the polymer or monomer having photoreactive groups.

[0212] The content of a polymer or monomer having a photoreactive group in a composition for forming a photoalignment film can be appropriately adjusted depending on the type of polymer or monomer or the thickness of the intended photoalignment film, but it is preferable to have at least 0.2 mass% with respect to the mass of the composition for forming a photoalignment film, and a range of 0.3 to 10 mass% is more preferable. Within a range where the characteristics of the photoalignment film are not significantly impaired, the composition for forming a photoalignment film may include polymer materials such as polyvinyl alcohol or polyimide or a photosensitizer.

[0213] A method for applying a composition for forming a photo-alignment film to a substrate may be the same as a method for applying an oriented composition to a substrate. Methods for removing the solvent from the applied composition for forming a photo-alignment film may include natural drying, ventilation drying, heat drying, and vacuum drying.

[0214] To irradiate polarized light, the method may involve directly irradiating polarized UV light onto a composition for forming a photoalignment film coated on a substrate from which the solvent has been removed, or by irradiating polarized light from the substrate side and transmitting the polarized light. It is particularly preferable that the polarized light be substantially parallel light. The wavelength of the irradiated polarized light is preferably in a wavelength range in which the photoreactive groups of a polymer or monomer having photoreactive groups can absorb light energy. Specifically, UV (ultraviolet) light in the wavelength range of 250 to 400 nm is particularly preferred. Examples of light sources used for the irradiation of polarized light include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF, with high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps being more preferred. Among these, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are preferred because they have a high emission intensity of ultraviolet light with a wavelength of 313 nm. Polarized UV can be irradiated by passing light from the above light source through a suitable polarizer.

[0215] As such polarizers, polarizing filters, polarizing prisms such as Glen Thomson or Glen Taylor, or wire grid type polarizers can be used.

[0216] In addition, when performing rubbing or polarization irradiation, if masking is performed, multiple regions (patterns) with different liquid crystal orientation directions may be formed.

[0217] A groove alignment film is a film having an uneven pattern or a plurality of grooves on the film surface. When a polymerizable liquid crystal compound is applied to a film having a plurality of straight grooves arranged at equal intervals, liquid crystal molecules are oriented along the grooves.

[0218] Methods for obtaining a groove alignment film include: a method of forming an uneven pattern by interposing an exposure mask having a pattern-shaped slit on the surface of a photosensitive polyimide film, and then performing development and rinsing treatments after exposure; a method of forming a layer of UV-curing resin before curing on a plate-shaped disc having grooves on the surface, transferring the formed resin layer to a substrate and then curing it; and a method of forming unevenness by pressing a roll-shaped disc having multiple grooves against a film of UV-curing resin before curing formed on a substrate, and then curing it.

[0219] The thickness of the alignment layer (an alignment layer or photoalignment layer containing an oriented polymer) is typically in the range of 10 to 10,000 nm, preferably in the range of 10 to 1,000 nm, more preferably in the range of 500 nm or less, even more preferably in the range of 10 to 200 nm, and particularly preferably in the range of 50 to 150 nm.

[0220] The present invention comprises a polarizing film comprising a polarizing film and a transparent film according to the present invention. The transparent film referred to herein means a film having transparency capable of transmitting light, particularly visible light, and transparency refers to a characteristic in which the transmittance for light rays with a wavelength of 380 to 780 nm is 80% or more. In the polarizing film of the present invention, the transparent film may be, for example, a transparent substrate described above, or a protective film for protecting the polarizing film. In the polarizing film of the present invention, the transparent film may be laminated only on one side of the polarizing film or laminated on both sides. When the polarizing film of the present invention comprises a plurality of transparent films, they may be identical or different from each other. Furthermore, the polarizing film and the transparent film may be in contact with each other or separated. Typically, the transparent film may be laminated to the polarizing film by interposing an adhesive layer or a pressure-sensitive adhesive layer.

[0221] In addition, the present invention includes a circular polarizer comprising a polarizing film and a phase difference film of the present invention. In the circular polarizer of the present invention, it is preferable that the phase difference film satisfies Equation (1) and Equation (2). In addition, when the phase difference film includes a layer other than a phase difference-expressing layer (phase difference-expressing layer), such as when the phase difference film is composed of a liquid crystal curing layer formed on a substrate film, it is preferable that the phase difference-expressing layer satisfies the optical properties represented by Equation (1) and Equation (2).

[0222] 100 ㎚ ≤ Re(550) ≤ 150 ㎚ (1)

[0223] Re(450) / Re(550) < 1 (2)

[0224] [In the equation, Re(λ) represents the frontal phase difference value for light of wavelength λ nm.]

[0225] If the phase difference film has a front phase difference value represented by (1) above, it functions as a so-called λ / 4 plate. The above equation (1) is preferably 120 nm ≤ Re(550) ≤ 150 nm.

[0226] A phase difference film satisfying the above equation (2) has so-called inverse wavelength dispersion and exhibits excellent polarization performance. The value of Re(450) / Re(550) is preferably 0.93 or less, more preferably 0.88 or less, even more preferably 0.86 or less, preferably 0.80 or more, and more preferably 0.82 or more.

[0227] The above front phase difference value can be adjusted by the film thickness dA of the phase difference film (phase difference expression layer). The front phase difference value is determined by the equation Re(λ) = (nx(λ) - ny(λ)) × dA [where dA represents the thickness of the phase difference film (phase difference expression layer), nx represents the principal refractive index at wavelength λ nm in a direction parallel to the plane of the phase difference film in the refractive index ellipsoid formed by the phase difference film, and ny represents the refractive index at wavelength λ nm in a direction parallel to the plane of the phase difference film and also orthogonal to the direction of nx in the refractive index ellipsoid formed by the phase difference film]. In order to obtain the desired front phase difference value (Re(λ): in-plane phase difference value of the phase difference layer at wavelength λ (nm), the three-dimensional refractive index and the film thickness dA need to be adjusted.

[0228] The above phase difference film may be a stretched film that imparts a phase difference by stretching a polymer, but from the perspective of thinning a circular polarizer, it is preferable to be composed of a polymer in an oriented state of the polymerizable liquid crystal compound as a cured product of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound. The phase difference film constituting the circular polarizer of the present invention can be manufactured by appropriately selecting and employing materials or methods conventionally known in the field, and as the polymerizable liquid crystal compound forming the phase difference film, for example, a liquid crystal compound described in Japanese Patent Publication No. 2011-207765, etc., may be used.

[0229] The thickness of the phase difference film can be appropriately selected depending on the applied display device, but from the perspective of thinning and flexibility, it is preferable that it be 0.1 to 10 μm, more preferable that it be 1 to 5 μm, and even more preferable that it be 1 to 3 μm.

[0230] The original polarizer of the present invention comprises a polarizing film or polarizing film and a phase difference film of the present invention, and may also include other layers other than these (such as a protective layer, a pressure-sensitive adhesive layer, etc.). In the original polarizer of the present invention, the polarizing film or polarizing film and the phase difference film of the present invention may be laminated with an adhesive layer or a pressure-sensitive adhesive layer interposed therebetween. Furthermore, in the original polarizer of the present invention, the phase difference film may be directly formed on the polarizing film of the present invention by directly applying a composition for forming a phase difference film to the polarizing film of the present invention.

[0231] In the circular polarizer of the present invention, the angle formed by the ground axis of the phase difference film and the absorption axis of the polarizing film is preferably substantially 45°. In addition, in the present invention, "substantially 45°" means 45° ± 5°.

[0232] The thickness of the circular polarizer of the present invention is preferably 10 to 300 μm, more preferably 20 to 200 μm, and even more preferably 25 to 100 μm, in terms of the flexibility or visibility of the display device.

[0233] The present invention includes a display device comprising a polarizing film of the present invention or a circular polarizing plate of the present invention.

[0234] The display device of the present invention can be obtained, for example, by laminating the polarizing film or circular polarizing plate of the present invention onto the surface of the display device through a pressure-sensitive adhesive layer.

[0235] 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 display devices, organic electroluminescence (EL) display devices, inorganic electroluminescence (EL) display devices, touch panel display devices, electron emission display devices (electric field emission display devices (FED, etc.), surface field emission display devices (SED)), electronic paper (display devices using electronic ink or electrophoretic elements), plasma display devices, projection display devices (display devices having a grating light valve (GLV) display device, digital micromirror device (DMD), etc.), and piezoelectric ceramic displays.

[0236] A liquid crystal display device includes any of the following: a transmissive liquid crystal display device, a transmissive liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, and a projection liquid crystal display device. These display devices may be display devices that display two-dimensional images, or stereoscopic display devices that display three-dimensional images. In particular, as display devices of the present invention, an organic EL display device and a touch panel display device are preferred, and an organic EL display device is particularly preferred.

[0237] Examples

[0238] The present invention will be explained in more detail below through examples and comparative examples. In the examples and comparative examples, “%” and “parts” refer to “mass%” and “mass parts”, respectively, unless otherwise specifically stated.

[0239] Comparative Example 1

[0240] A polymerizable liquid crystal composition (1) was obtained by mixing the following components and stirring at 80°C for 1 hour. For the polymerizable liquid crystal compound and dichroic pigment, the polymerizable liquid crystal compound and azo pigment described in the example of Japanese Patent Publication No. 2013-101328 were used.

[0241] · Polymerizable liquid crystal compounds :

[0242] [Chemical Formula 15]

[0243]

[0244] [Chemical Formula 16]

[0245]

[0246] · Dichroic pigment :

[0247] azo pigment ;

[0248] [Chemical Formula 17]

[0249]

[0250] [Chemical Formula 18]

[0251]

[0252] [Chemical Formula 19]

[0253]

[0254] · Polymerization initiator:

[0255] 2-Dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369; manufactured by Chiba Specialty Chemicals Co., Ltd.) 6 parts

[0256] · Leveling agent :

[0257] Polyacrylate compound (BYK-361N; manufactured by BYK-Chemie) Part 1.2

[0258] · Solvent :

[0259] o-xylene 400 parts

[0260] In addition, polymerizable liquid crystal compositions (2) to (10) were obtained in the same manner as polymerizable liquid crystal composition (1), except that 1 part of the antioxidant described below was mixed with 100 parts by mass of polymerizable liquid crystal composition (1) according to Table 1.

[0261] Examples 1 to 4 and Comparative Examples 2 to 6

[0262] In the polymerizable liquid crystal composition (1), the polymerizable liquid crystal compositions of Examples 1 to 4 and Comparative Examples 2 to 6 (polymerizable liquid crystal compositions (2) to (10)) were prepared in the same manner as Comparative Example 1, except that 1 part by mass of the following antioxidant was mixed in addition to the components described above in the polymerizable liquid crystal composition (1).

[0263] [Chemical Formula 20]

[0264]

[0265] (Antioxidant A: 2-Mercaptobenzimidazole)

[0266] Used in polymerizable liquid crystal compositions (2).

[0267] [Chemical Formula 21]

[0268]

[0269] (Antioxidant B: 10-Methylphenothiazine)

[0270] Used in polymerizable liquid crystal compositions (3).

[0271] [Chemical Formula 22]

[0272]

[0273] (Antioxidant C: 2-Methoxyphenothiazine)

[0274] Used in polymerizable liquid crystal compositions (4).

[0275] [Chemical Formula 23]

[0276]

[0277] (Antioxidant D: 2-ethylthiophenothiazine)

[0278] Used in polymerizable liquid crystal compositions (5).

[0279] [Chemical Formula 24]

[0280]

[0281] (Antioxidant E: 4-butoxy-4'-hydroxybiphenyl)

[0282] Used in polymerizable liquid crystal compositions (6).

[0283] [Chemical Formula 25]

[0284]

[0285] (Antioxidant F: 4-ethoxy-4'-hydroxybiphenyl)

[0286] Used in polymerizable liquid crystal compositions (7).

[0287] [Chemical Formula 26]

[0288]

[0289] (Antioxidant G: Sumilizer TPL, manufactured by Sumitomo Chemical Co., Ltd.)

[0290] Used in polymerizable liquid crystal compositions (8).

[0291] [Chemical Formula 27]

[0292]

[0293] (Antioxidant H: Sumilizer TP-D, manufactured by Sumitomo Chemical Co., Ltd.)

[0294] Used in polymerizable liquid crystal compositions (9).

[0295] [Chemical Formula 28]

[0296]

[0297] (Antioxidant I: DTDPA)

[0298] Used in polymerizable liquid crystal compositions (10).

[0299] In addition, polarizing films of Examples 1 to 4 and Comparative Examples 1 to 6 were produced using polymerizable liquid crystal compositions (1) to (10) in the following order.

[0300] (1) Fabrication of a photo-alignment film onto a substrate

[0301] (i) Preparation of a composition for forming a photo-alignment film

[0302] A composition for forming a photo-alignment film was obtained by mixing the following components described in Japanese Patent Publication No. 2013-033249 and stirring the obtained mixture at 80°C for 1 hour.

[0303] · Photo-oriented polymer :

[0304] [Chemical Formula 29]

[0305]

[0306] Part 2

[0307] · Solvent :

[0308] o-xylene 98 parts

[0309] (ii) Formation of photo-alignment layer

[0310] A triacetylcellulose film (KC8UX2M, manufactured by Konica Minolta Corp.) was used as a transparent substrate, and after corona treatment was performed on the film surface, the composition for forming a photoalignment film was applied and dried at 120°C to obtain a dried film. Polarized UV was irradiated onto this dried film to form a photoalignment film, and a film with the photoalignment film attached was obtained. Polarized UV treatment was performed using a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Electric Co., Ltd.) under conditions where the intensity measured at a wavelength of 365 nm was 100 mJ.

[0311] (2) Manufacturing of polarizing film

[0312] A polymerizable liquid crystal composition (2) was applied to a film having a photoalignment layer attached as described above by the bar coating method (#9 30 mm / s), and the polymerizable liquid crystal compound was phase-transitioned into a liquid phase by heating and drying in a drying oven at 120°C for 1 minute, and then cooled to room temperature to phase-transition the polymerizable liquid crystal compound into a smectic liquid crystal state. Subsequently, using a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Electric Co., Ltd.), ultraviolet light with an exposure amount of 1000 mJ / ㎠ (based on 365 nm) was irradiated onto the layer formed from the polymerizable liquid crystal composition, thereby polymerizing the polymerizable liquid crystal compound contained in the dried film while maintaining the smectic liquid crystal state of the polymerizable liquid crystal compound, forming a polarizing film from the dried film, and a polarizing film was obtained by stacking a transparent substrate, a photoalignment layer, and a polarizing film in this order. The thickness of the polarizing film at this time was measured by a laser microscope (OLS3000 manufactured by Olympus Inc.) and was 2.3 μm.

[0313] For this polarizing film, X-ray diffraction measurements were performed using the X-ray diffraction device X' Pert PRO MPD (manufactured by Spectris Co., Ltd.), and a sharp diffraction peak (Bragg peak) with a full width at half maximum (FWHM) of approximately 0.17° was obtained at 2θ = 20.2°.

[0314] In addition, equivalent results were obtained with incidence from the direction perpendicular to the rubbing. The order period (d) obtained from the peak position is approximately 4.4 Å, and it was confirmed that a structure reflecting a higher-order smectic phase is formed.

[0315] (3) Manufacturing of laminates

[0316] In addition, after performing corona treatment on the polarizing film surface of the polarizing film obtained above, an aqueous solution (viscosity: 92 cP) was applied to the corona-treated surface by adding 7 parts of carboxyl group modified polyvinyl alcohol ["Curare Poval KL318" manufactured by Curare Inc.] and 3.5 parts of water-soluble polyamide epoxy resin ["Sumirez Resin 650" obtained from Sumika Chemtex Co., Ltd. (aqueous solution with a solid content concentration of 30 mass%)] to 100 parts of water, using a wire bar coater (#30). By drying at 80°C for 5 minutes, the aqueous solution was dried to form a protective layer, and a polarizing film with the protective layer attached was manufactured. In addition, a laminate was obtained by laminating glass (manufactured by Corning, EagleXG) onto a protective layer, interposing an adhesive layer formed from a pressure-sensitive adhesive (manufactured by Lintec Co., Ltd., film thickness 25 μm).

[0317] <Measurement of Polarization Degree Py>

[0318] The polarization degree Py of the laminate was measured as follows. Transmittance in the transmission axis direction (Ta) and transmittance in the absorption axis direction (Tb) in the wavelength range of 380 nm to 780 nm were measured using the double-beam method with a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation) equipped with a folder with a polarizer. A mesh that cuts the light intensity by 50% was installed on the reference side of the folder.

[0319] The degree of polarization at each wavelength was calculated from the following (Equation 1), and the degree of visual sensitivity correction was performed using the 2-degree field of view (C light source) of JIS Z 8701 to calculate the degree of visual sensitivity correction polarization (Py).

[0320] Polarization degree Py (%) = (Ta - Tb) / (Ta + Tb) × 100 (Equation 1)

[0321] <Measurement of absorbance in the transmission direction>

[0322] In the same manner as above, the absorbance (A1) in the direction of the transmission axis was measured using the double beam method with a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation) equipped with a folder with a polarizer attached.

[0323] <Evaluation of Lightfastness>

[0324] Light resistance was evaluated for the laminates of Examples 1 to 4 and Comparative Examples 1 to 6 according to the following method. The results are shown in Table 1.

[0325] The above laminate was placed with the surface of the triacetylcellulose film, which is the substrate, facing upward, and inserted into a light resistance tester (Santest XLS+; manufactured by ATLAS). After irradiating with light under conditions of an integrated light intensity of 96120 KJ / m², the polarization degree Py and the absorbance A1 in the transmission axis direction of the laminate were measured again. The rate of change ΔPy of the polarization degree Py before and after the light resistance test and the change in absorbance in the transmission axis direction at 420 nm, which is the criterion for suppressing yellowing, were calculated and evaluated according to the following criteria.

[0326] <Evaluation Criteria>

[0327] Change in polarization

[0328] A: The absolute value of the change in polarization degree |ΔPy| is less than 0.8

[0329] B: The absolute value of the change in polarization degree |ΔPy| is 0.8 or greater and less than 1.2

[0330] C: The absolute value of the change in polarization degree |ΔPy| is 1.2 or greater

[0331] change in absorbance

[0332] A: Change in absorbance along the transmission axis is 0% or more and less than 5%

[0333] B: Change in absorbance along the transmission axis is 5% or more and less than 10%

[0334] C: Change in absorbance along the transmission axis is 10% or more

[0335]

[0336] The polarizing films of Examples 1 to 4 yielded good results in each evaluation.

Claims

Claim 1 A polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound, an organic dichroic pigment, and a sulfur-based antioxidant, wherein the polymerizable liquid crystal compound has at least one radical polymerizable group, the polymerizable liquid crystal compound exhibits a higher-order smectic liquid crystal phase, the sulfur-based antioxidant has an aromatic ring structure and a thiol structure or a thioether structure, the weight average molecular weight of the sulfur-based antioxidant is 100 or more and 400 or less, and the organic dichroic pigment is an azo pigment. Claim 2 A polymerizable liquid crystal composition according to claim 1, wherein the sulfur-based antioxidant is at least one selected from the group consisting of a thiol compound having an aromatic ring, a sulfide compound having an aromatic ring, and a cyclic sulfide compound having an aromatic ring. Claim 3 delete Claim 4 delete Claim 5 A polymerizable liquid crystal composition according to claim 1, wherein the organic dichroic pigment has an aromatic ring structure. Claim 6 A polymerizable liquid crystal composition according to claim 1, wherein the content of a sulfur-based antioxidant is 0.1 to 3 parts by mass per 100 parts by mass of the polymerizable liquid crystal compound. Claim 7 A polarizing film composed of a cured film of the polymerizable liquid crystal composition described in claim 1. Claim 8 In claim 7, a polarizing film exhibiting a Bragg peak in X-ray diffraction measurements. Claim 9 In claim 7, a polarizing film having a film thickness in the range of 0.5 to 4 μm. Claim 10 A polarizing film comprising a polarizing film and a transparent film as described in claim 7. Claim 11 A circular polarizer comprising a polarizing film and a phase difference film as described in claim 7. Claim 12 In claim 11, the phase difference film is a circular polarizer satisfying equations (1) and (2): 100 nm ≤ Re(550) ≤ 150 nm (1) Re(450) / Re(550) < 1 (2) [wherein Re(λ) represents the frontal phase difference value for light of wavelength λ nm]. Claim 13 A display device comprising a polarizing film described in any one of claims 7 to 9, a polarizing film described in claim 10, or a circular polarizer described in claim 11 or 12.

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