CN113302528B

CN113302528B - Circularly polarizing plate and organic EL display device using same

Info

Publication number: CN113302528B
Application number: CN202080009401.7A
Authority: CN
Inventors: 幡中伸行; 村野耕太
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2019-02-12
Filing date: 2020-02-06
Publication date: 2023-09-22
Anticipated expiration: 2040-02-06
Also published as: CN113302528A; TWI846815B; JP7549452B2; JP2020134934A; TW202040181A; KR20210127704A; WO2020166476A1

Abstract

The present invention provides a circularly polarizing plate comprising a polarizing film comprising a dichroic dye and a transparent protective film having a thickness of 10 [ mu ] m or more and 80 [ mu ] m or less, and a retardation film comprising a cured product of a composition comprising a polymerizable liquid crystal compound B having a thickness of 5 [ mu ] m or less, wherein the polymerizable liquid crystal compound B is a compound having an ester bond in a molecular structure, and wherein the equilibrium water content of the polarizing plate is 1.5 mass% or less at a temperature of 23 ℃ and a humidity of 50%.

Description

Circularly polarizing plate and organic EL display device using same

Technical Field

The present invention relates to a circularly polarizing plate and an organic EL display device using the same.

Background

In recent years, with the popularization of thin displays, displays (organic EL display devices) having organic EL panels mounted thereon have been increasingly popular. In the organic EL panel, external light is reflected by the internal metal electrode, and thus a clear black display cannot be obtained. In order to solve this problem, the circularly polarizing plate is provided on the viewing surface, whereby external light reflection can be suppressed. That is, the lamination sequence from the viewer is a circularly polarizing plate→an organic EL display. The circular polarizing plate can be generally produced by laminating a polarizing plate and a retardation film. As the polarizing plate, a product obtained by laminating a transparent protective film on a polarizer obtained by stretching PVA (polyvinyl alcohol) and dyeing with iodine is generally used, and as the retardation film, a stretched film or a retardation film (λ/4 plate) in which liquid crystal molecules are oriented may be used. In this case, a λ/4 plate exhibiting a property (inverse wavelength dispersion property) that the birefringence increases as the wavelength increases can be preferably used.

Disclosure of Invention

Problems to be solved by the application

In the organic EL display device, there is a problem that the organic EL layer is degraded by oxygen and moisture depending on the use environment, and does not emit light, and both surfaces of the organic EL panel are sometimes protected by a substrate having low moisture permeability such as glass. The outermost surface of the panel may be protected by a base material having low water resistance or low moisture permeability. However, such a constitution is known to have a problem that color change occurs in a high-temperature environment depending on the kind of the retardation film. The inventors of the present application have made intensive studies and as a result, have found that a minute amount of moisture contained in a protective film, polyvinyl alcohol, or the like, which forms a polarizing plate, remains in the system, and hydrolysis of the retardation film is caused by the moisture, thereby causing a color change.

Accordingly, an object of the present application is to provide an excellent circularly polarizing plate with little color change under a high temperature environment and an organic EL display device with the circularly polarizing plate.

Means for solving the problems

The present application relates to the following preferred embodiments [1] to [12].

[1] A circularly polarizing plate comprising a polarizing film comprising a dichroic dye and a transparent protective film having a thickness of 10 μm to 80 μm, and a retardation film comprising a cured product of a composition comprising a polymerizable liquid crystal compound B,

The retardation film has a thickness of 5 μm or less,

the polymerizable liquid crystal compound B is a compound having an ester bond in its molecular structure,

the polarizing plate has an equilibrium water content of 1.5 mass% or less at a temperature of 23 ℃ and a relative humidity of 50%.

[2] The circularly polarizing plate as claimed in [1], wherein the dichroic dye is an azo dye.

[3] The circularly polarizing plate as recited in [1] or [2], wherein the transparent protective film is a cycloolefin resin.

[4] The circularly polarizing plate as claimed in any one of [1] to [3], wherein the polarizing film further comprises a cured product of a polymerizable liquid crystal compound A having an acryloyloxy group or a methacryloyloxy group as a polymerizable group.

[5] The circularly polarizing plate as claimed in any one of [1] to [4], wherein the polarizing film exhibits a Bragg peak in an X-ray diffraction measurement.

[6] The circularly polarizing plate as claimed in [4], wherein the cured product of the polymerizable liquid crystal compound A exhibits a smectic liquid crystal phase and is cured in a horizontally aligned state.

[7] The circularly polarizing plate as claimed in any one of [1] to [6], wherein the retardation film satisfies the following formula (1).

100≤Re(550)≤180 (1)

[ wherein Re (550) represents the in-plane phase difference value at a wavelength of 550 nm. ]

[8] The circularly polarizing plate as claimed in any one of [1] to [7], wherein the retardation film satisfies the formula (2).

Re(450)/Re(550)<1 (2)

[ wherein Re (450) and Re (550) represent the in-plane phase difference values at wavelengths of 450nm and 550nm, respectively. ]

[9] The circularly polarizing plate as claimed in any one of [1] to [8], wherein an angle between a slow axis of the retardation film and an absorption axis of the polarizing film is substantially 45 °.

[10] The circularly polarizing plate as claimed in any one of [1] to [9], wherein the polymerizable liquid crystal compound B has at least one polymerizable group selected from the group consisting of an acryloyloxy group and a methacryloyloxy group.

[11] The circularly polarizing plate as claimed in any one of [1] to [10], wherein the polymerizable liquid crystal compound B is a compound represented by the following formula (II).

[ chemical formula 1]

In the formula (II) of the present invention,

ar represents a divalent aromatic group which may have a substituent.

G ¹ G (G) ² Each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group.

L ¹ L and L ² Each independently is a divalent linking group having an ester structure.

T ¹ T and T ² Each independently is a single bond or a divalent linking group.

h and i each independently represents an integer of 0 to 3, satisfying the relation 1.ltoreq.h+i. Here, T is when 2.ltoreq.h+i ¹ T and T ² 、G ¹ G (G) ² Each of which may be the same as or different from each other.

E ¹ E and E ² Each independently represents an alkanediyl group having 1 to 17 carbon atoms, wherein hydrogen atoms contained in the alkanediyl group may be substituted with halogen atoms, -CH contained in the alkanediyl group ₂ Can be substituted by-O-, -S-, -a COO-substitution, and, having a plurality of-O-, in the case of-S-, -COO-, are not contiguous with each other.

P ¹ P ² Independently of each other, a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

[12] The circularly polarizing plate as claimed in any one of [1] to [11], wherein a transparent protective film is laminated on only one surface of the polarizing film.

[13] An organic EL display device comprising the circularly polarizing plate as claimed in any one of [1] to [12 ].

ADVANTAGEOUS EFFECTS OF INVENTION

The circularly polarizing plate of the present invention can prevent color change even in a high temperature environment.

Detailed Description

The circularly polarizing plate is composed of a polarizing plate and a retardation film. In the present invention, it is necessary to control the equilibrium moisture content of the polarizing plate at a temperature of 23 ℃ and a humidity of 50% to 1.5 mass% or less. The equilibrium water content is defined as: in air with a certain temperature and humidity, the moisture content in the material reaches the equilibrium state in the atmosphere. In the present invention, after a polarizing plate (size: width: 4cm, length: 10 cm) was kept in a clean room at a temperature of 23 ℃ and a relative humidity of 50% for 1 day and the mass was measured, the polarizing plate was dried at 105 ℃ for 1 hour, the mass was measured, and the value obtained was calculated as the equilibrium water content by the following formula:

(mass at 23℃and 50% relative humidity-mass after 1 hour of drying at 105 ℃) x 100 (mass at 23℃and 50% relative humidity)

In the present invention, when the equilibrium water content of the polarizing plate is higher than 1.5 mass%, the color change of the circularly polarizing plate at high temperature is liable to be caused, which is not preferable. The equilibrium water content of the polarizing plate is preferably 1.0 mass% or less, more preferably 0.5 mass% or less. The lower limit of the equilibrium moisture content of the polarizing plate may be 0. When the equilibrium water content of the polarizing plate is higher than 1.5 mass%, the equilibrium water content can be reduced by drying. The drying may be suitably performed by standing in a dry environment or the like, in addition to heating.

The circularly polarizing plate of the present invention comprises a polarizing plate comprising a polarizing film comprising a dichroic dye and a transparent protective film having a thickness of 10 [ mu ] m or more and 80 [ mu ] m or less, and a retardation film which is a cured product of a composition comprising a polymerizable liquid crystal compound B.

< polarizing film >

The polarizing film has a function of light absorption anisotropy. The polarizing film may be a stretched film having a dichroic dye adsorbed thereto, or may be a cured product of a composition containing a horizontally oriented polymerizable liquid crystal compound and a horizontally oriented dichroic dye. From the viewpoint of the above-described balance of the water content, the polarizing film is more preferably a polarizing film formed of a polymer of a polymerizable liquid crystal compound.

A film including a stretched film having a dichromatic pigment adsorbed thereon as a polarizing film can be generally produced by the following steps: a step of uniaxially stretching a polyvinyl alcohol resin film; a step of dyeing the polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye; a step of treating the polyvinyl alcohol resin film having the dichromatic pigment adsorbed thereto with an aqueous boric acid solution; and a step of washing with water after the treatment with the aqueous boric acid solution.

The polyvinyl alcohol resin is obtained by saponifying a polyvinyl acetate resin. As the polyvinyl acetate resin, a copolymer of vinyl acetate and other monomers copolymerizable therewith may be used in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The polymerization degree of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably 1,500 to 5,000.

A film made of such a polyvinyl alcohol resin can be used as a green film (japanese: raw film ) of a polarizing film. The method for forming the polyvinyl alcohol resin into a film is not particularly limited, and the film can be formed by a known method. The thickness of the polyvinyl alcohol-based green film may be, for example, about 10 to 150. Mu.m.

The uniaxial stretching of the polyvinyl alcohol resin film may be performed before dyeing with a dichroic dye, simultaneously with dyeing, or after dyeing. In the case of uniaxial stretching after dyeing, the uniaxial stretching may be performed before boric acid treatment or may be performed in boric acid treatment. In addition, uniaxial stretching may be performed in a plurality of stages among them. In the case of uniaxial stretching, uniaxial stretching may be performed between rolls having different peripheral speeds, or uniaxial stretching may be performed using a hot roll. The uniaxial stretching may be a dry stretching in which stretching is performed in the atmosphere, or a wet stretching in which stretching is performed in a state in which a polyvinyl alcohol resin film is swollen with a solvent. The stretching ratio is usually about 3 to 8 times.

Dyeing of the polyvinyl alcohol resin film with the dichromatic pigment can be performed, for example, by immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichromatic pigment.

As the dichroic dye, specifically, iodine or a dichroic organic dye can be used. Examples of the organic dye having dichroism include a dichroism direct dye formed of a disazo compound such as c.i. direct red (DIRECT RED) 39, and a dichroism direct dye formed of a compound such as trisazo or tetraazo. The polyvinyl alcohol resin film is preferably immersed in water before the dyeing treatment.

When iodine is used as the dichromatic pigment, a method of immersing a polyvinyl alcohol resin film in an aqueous solution containing iodine and potassium iodide to dye the film can be generally employed.

The iodine content in the aqueous solution is usually about 0.01 to 1 part by mass per 100 parts by mass of water. The content of potassium iodide is usually about 0.5 to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ℃. The immersion time (dyeing time) for immersing in the aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of immersing a polyvinyl alcohol resin film in an aqueous solution containing a water-soluble dichroic dye and dyeing the film is generally employed.

The content of the dichroic organic dye in the aqueous solution is usually 1×10 relative to 100 parts by mass of water ^-4 About 10 parts by mass, preferably 1X 10 ^-3 About 1 part by mass, more preferably 1X 10 ^-3 ～1×10 ^-2 Mass parts. The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing auxiliary. The temperature of the aqueous solution of the dichroic dye used for dyeing is usually about 20 to 80 ℃. The immersion time (dyeing time) in the aqueous solution is usually about 10 to 1,800 seconds.

Boric acid treatment after dyeing with a dichroic dye can be generally performed by immersing the dyed polyvinyl alcohol resin film in an aqueous boric acid solution. The boric acid content in the aqueous boric acid solution is usually about 2 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. When iodine is used as the dichromatic pigment, the aqueous boric acid solution preferably contains potassium iodide, and the content of potassium iodide in this case is usually about 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass, relative to 100 parts by mass of water. The immersion time in the aqueous boric acid solution is usually about 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid treatment is usually 50℃or higher, preferably 50 to 85℃and more preferably 60 to 80 ℃.

In general, the polyvinyl alcohol resin film after boric acid treatment may be subjected to a water washing treatment. The water-washing treatment may be performed, for example, by immersing the boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ℃.

The immersion time is usually about 1 to 120 seconds.

The polarizing film may be obtained by performing a drying treatment after washing with water. The drying treatment may be performed using, for example, a hot air dryer or a far infrared heater. The drying treatment temperature is usually about 30 to 100 ℃, preferably 50 to 80 ℃. The drying time is usually about 60 to 600 seconds, preferably 120 to 600 seconds. Through the drying treatment, the water ratio of the polaroid can be reduced to a practical degree. The water content is usually about 5 to 20% by mass, preferably 8 to 15% by mass. When the moisture content is less than 5% by mass, the flexibility of the polarizing film is lost, and the polarizing film may be damaged or broken after drying. In addition, if the water content exceeds 20 mass%, the heat stability of the polarizing film may be deteriorated.

The thickness of the polarizing film obtained by uniaxially stretching the polyvinyl alcohol resin film, dyeing with a dichroic dye, boric acid treatment, washing with water, and drying as described above is preferably 5 to 40 μm.

In the case of a polarizing film which is a cured product of a composition containing a horizontally oriented polymerizable liquid crystal compound and a horizontally oriented dichroic dye (hereinafter, may be referred to as a polymerizable liquid crystal composition (a)), the polymerizable liquid crystal compound may be a thermotropic liquid crystal or a lyotropic liquid crystal, but in the case of mixing with a dichroic dye, it is preferably a thermotropic liquid crystal. In the case of a thermotropic liquid crystal, the thermotropic liquid crystal compound may be a thermotropic liquid crystal compound exhibiting a nematic liquid crystal phase or a smectic liquid crystal phase. When the polymerizable liquid crystal compound is formed into a cured film by polymerization reaction to exhibit a polarizing function, the liquid crystal state exhibited by the polymerizable liquid crystal compound is preferably a smectic phase. Specific examples of such compounds are described below.

The polymerizable liquid crystal composition (a) contains a polymerizable liquid crystal compound having at least 1 polymerizable group and preferably exhibiting smectic liquid crystal properties (hereinafter also referred to as "polymerizable liquid crystal compound (a)"). By using a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity, a polarizing film having a high alignment order can be formed.

The liquid crystal state displayed by the polymerizable liquid crystal compound (a) is preferably a smectic phase (smectic liquid crystal state), and is more preferably a higher order smectic phase (higher order smectic liquid crystal state) from the viewpoint of enabling higher alignment order. The higher order smectic phase herein means 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, smectic B phase, smectic F phase and smectic I phase are more preferable. The liquid crystal property may be a thermotropic liquid crystal or a lyotropic liquid crystal, but is preferably a thermotropic liquid crystal in view of enabling precise film thickness control. The polymerizable liquid crystal compound may be a monomer, or may be an oligomer or polymer obtained by polymerizing a polymerizable group.

The polymerizable liquid crystal compound (a) is a liquid crystal compound having at least 1 polymerizable group. Here, the polymerizable group means a group capable of participating in polymerization reaction by a living radical, an acid, or the like generated by a polymerization initiator. Examples of the polymerizable group included in the polymerizable liquid crystal compound (a) include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an epoxyethyl group, and an oxetanyl group. Among them, a radical polymerizable group is preferable, and an acryloyloxy group, a methacryloyloxy group, a vinyl group, and a vinyloxy group are more preferable, and an acryloyloxy group and a methacryloyloxy group are still more preferable.

The polymerizable liquid crystal compound (a) is not particularly limited as long as it is a liquid crystal compound having at least 1 polymerizable group, and known polymerizable liquid crystal compounds can be used, and examples thereof include compounds represented by the following formula (A1) (hereinafter, also referred to as "polymerizable liquid crystal compounds (A1)").

U ¹ -V ¹ -W ¹ -(X ¹ -Y ¹ -) _n -X ² -W ² -V ² -U ² (A1)

In the formula (A1),

X ¹ x is X ² Independently of each other, a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group or a nitro group, and a 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. Preferably X ¹ X is X ² At least one of them is a1, 4-phenylene group which may have a substituent or a cyclohexane-1, 4-diyl group which may have a substituent.

Y ¹ Is a single bond or a divalent linking group.

n is 1-3, and when n is 2 or more, a plurality of X ¹ May be the same as or different from each other. X is X ² Can be combined with a plurality of X ¹ Either one or all of them may be the same or different. When n is 2 or more, a plurality of Y ¹ May be the same as or different from each other. From the viewpoint of liquid crystal property, n is preferably 2 or more.

U ¹ Represents a hydrogen atom or a (meth) acryloyloxy group.

U ² Represents (meth) acryloyloxyA base.

W ¹ W and W ² Independently of one another, a single bond or a divalent linking group.

V ¹ V (V) ² Independently of each other, represents an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and the-CH constituting the alkanediyl group ₂ -can be replaced by-O-, -CO-, -S-or NH-.]

In the polymerizable liquid crystal compound (A1), X ¹ X is X ² Independently of one another, preferably 1, 4-phenylene which may have substituents, or cyclohexane-1, 4-diyl which may have substituents, X ¹ X is X ² At least one of them is a1, 4-phenylene group which may have a substituent, or a cyclohexane-1, 4-diyl group which may have a substituent, and preferably a trans-cyclohexane-1, 4-diyl group. Examples of the substituent optionally included in the 1, 4-phenylene group which may have a substituent or the cyclohexane-1, 4-diyl group which may have a substituent include an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group and a butyl group, a cyano group, a chlorine atom, a fluorine atom and other halogen atoms. Preferably unsubstituted.

The polymerizable liquid crystal compound (A1) is preferably a moiety represented by the formula (A1-1) in the formula (A1) (hereinafter referred to as a partial structure (A1-1)) in view of easy occurrence of smectic liquid crystallinity. Is of an asymmetric structure.

-(X ¹ -Y ¹ -) _n -X ² - (A1-1)

[ in the formula, X ¹ 、Y ¹ 、X ² And n each represents the same as above. A kind of electronic device

As the polymerizable liquid crystal compound (A1) having an asymmetric partial structure (A1-1), for example, there may be mentioned a compound having n of 1 and 1X ¹ And X is ² Polymerizable liquid crystal compounds (A1) having different structures from each other. In addition, there may be mentioned: n is 2 and 2Y ¹ Polymerizable liquid crystal compounds (A1) having the same structure as each other, wherein 2X ¹ 1X are the same structure as each other ² To and from these 2X ¹ Different structures; 2X ¹ W and W in (b) ¹ Bonded X ¹ To be with another X ¹ X is X ² Of a different structure, and another X ¹ And X is ² The polymerizable liquid crystal compounds (A1) have the same structure as each other. Further, n is 3 and 3Y's are exemplified ¹ Polymerizable liquid crystal compounds (A1) having the same structure as each other, wherein 3X's are ¹ 1X ² Any one of them has a structure different from the other 3.

Y ¹ preferably-CH ₂ CH ₂ -、-CH ₂ O-、-CH ₂ CH ₂ O-, -COO-, -OCOO-, a single bond, -N=N-, -CR ^a ＝CR ^b -、-C≡C-、-CR ^a =n-or-CO-NR ^a -。R ^a R is R ^b Independently of each other, represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y is Y ¹ More preferably-CH ₂ CH ₂ -, -COO-or a single bond, with a plurality of Y's present ¹ In the case of (2), with X ² Bonded Y ¹ More preferably-CH ₂ CH ₂ -or-CH ₂ O-。X ¹ X is X ² In the case of the same structure, it is preferable that there are at least 2Y's having different bonding modes ¹ . There are plural Y's having different bonding modes from each other ¹ In the case of (2), the structure is asymmetric, and thus, smectic liquid crystallinity tends to be easily exhibited.

U ² Is (meth) acryloyloxy. U (U) ¹ Is a hydrogen atom or a (meth) acryloyloxy group, preferably a (meth) acryloyloxy group. U is preferable from the viewpoint of improving interlayer adhesion and heat resistance of the polarizing film ¹ U and U ² Are (meth) acryloyloxy groups. The (meth) acryloyloxy group may be in a polymerized state or an unpolymerized state, and is preferably in an unpolymerized state.

As V ¹ V (V) ² Examples of the alkanediyl group include methylene, ethylene, propane-1, 3-diyl, butane-1, 4-diyl, pentane-1, 5-diyl, hexane-1, 6-diyl, heptane-1, 7-diyl, octane-1, 8-diyl, decane-1, 10-diyl, tetradecane-1, 14-diyl and eicosane-1, 20-diyl. V (V) ¹ V (V) ² The alkanediyl group having 2 to 12 carbon atoms is preferable, and the alkanediyl group having 6 to 12 carbon atoms is more preferable.

Examples of the substituent optionally contained in the alkanediyl group include a cyano group and a halogen atom, and the alkanediyl group is preferably unsubstituted, more preferably unsubstituted, linear alkanediyl group.

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

Specifically, the polymerizable liquid crystal compound (a) is more preferably a polymerizable liquid crystal compound having a structure represented by the formulae (a-a) to (a-i) and exhibiting smectic liquid crystallinity. From the viewpoint of easy display of high-order smectic liquid crystal property, the structure represented by formula (A-a), formula (A-b) or formula (A-c) is more preferable. In the formulae (A-a) to (A-i), the term "bond" means a bond (single bond).

[ chemical formula 2]

Specific examples of the polymerizable liquid crystal compound (A1) include compounds represented by the formulae (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 a trans-form.

[ chemical formula 3]

[ chemical formula 4]

[ chemical formula 5]

[ chemical formula 6]

[ chemical formula 7]

Of these, at least one compound selected from the group consisting of the compounds represented by the 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 preferable. The polymerizable liquid crystal compound (A1) may be used alone or in combination of two or more.

The polymerizable liquid crystal compound (A1) can be produced by a known method described in, for example, recl.Trav.Chim.Pays-Bas,115,321-328 (1996) of Lub et al, or Japanese patent No. 4719156.

The polymerizable liquid crystal composition (a) may contain other polymerizable liquid crystal compounds than the polymerizable liquid crystal compound (a) as long as the effect of the present invention is not impaired, and the ratio of the polymerizable liquid crystal compound (a) to the total mass of all the polymerizable liquid crystal compounds contained in the polymerizable liquid crystal composition (a) is preferably 51 mass% or more, more preferably 70 mass% or more, and even more preferably 90 mass% or more from the viewpoint of obtaining a polarizing film having a high alignment order.

In the case where the polymerizable liquid crystal composition (a) contains 2 or more polymerizable liquid crystal compounds (a), at least 1 of them may be the polymerizable liquid crystal compound (A1), or all of them may be the polymerizable liquid crystal compound (A1). By combining a plurality of polymerizable liquid crystal compounds, liquid crystallinity may be temporarily maintained even at a temperature equal to or lower than the liquid crystal-crystalline phase transition temperature.

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

The polymerizable liquid crystal composition (a) contains a dichroic dye. Here, the dichroic dye means a dye having a property that the absorbance in the long axis direction of the molecule is different from the absorbance in the short axis direction. The dichroic dye is a dye which exhibits dichroism in conjunction with alignment of a liquid crystal compound, and may itself have polymerizability or liquid crystallinity. The dichroic dye usable in the present invention is not particularly limited as long as it is a dichroic dye having the above properties, and may be a dye or a pigment. In addition, 2 or more dyes or pigments may be used in combination, respectively, or may be used in combination.

As the dichroic dye, a dye having a maximum absorption wavelength (. Lambda.) in the range of 300 to 700nm is preferable _MAX ) Is a dichroic dye of (a). Examples of such a dichroic dye include acridine dye, oxazine dye, cyanine dye, naphthalene dye, azo dye, and anthraquinone dye.

Examples of the azo dye include monoazo dye, disazo dye, trisazo dye, tetrazo dye, stilbene azo dye, and the like, and preferably the disazo dye and trisazo dye include, for example, a compound represented by the formula (I) (hereinafter, also referred to as "compound (I)").

K ¹ (-N＝N-K ² ) _p -N＝N-K ³ (I)

[ in formula (I), K ¹ K is as follows ³ Independently of each other, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or a monovalent heterocyclic group which may have a substituent. K (K) ² Represents p-phenylene which may have a substituent, naphthalene-1, 4-diyl which may have a substituent, or a divalent heterocyclic group which may have a substituent. p represents an integer of 1 to 4. When p is an integer of 2 or more, a plurality of K ² May be the same as or different from each other. In the range where absorption is exhibited in the visible light region, -n=n-bondsCan be replaced by-C=C-, -COO-, -NHCO-, -N=CH-bond.]

Examples of the monovalent heterocyclic group include a group obtained by removing 1 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 2 hydrogen atoms from the heterocyclic compound.

As K ¹ K is as follows ³ Phenyl, naphthyl and monovalent heterocyclic groups, K ² The substituent optionally contained in the p-phenylene group, naphthalene-1, 4-diyl group and divalent heterocyclic group in (a) may be an alkyl group having 1 to 4 carbon atoms; alkoxy groups having 1 to 4 carbon atoms such as methoxy, ethoxy and butoxy groups; fluorinated alkyl groups having 1 to 4 carbon atoms such as trifluoromethyl; cyano group; a nitro group; a halogen atom; substituted or unsubstituted amino groups such as amino, diethylamino and pyrrolidinyl (substituted amino means amino groups having 1 or 2 alkyl groups having 1 to 6 carbon atoms or amino groups having 2 substituted alkyl groups bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms, unsubstituted amino groups being-NH) ₂ . ) Etc.

Among the compounds (I), preferred are compounds represented by any of the following formulas (I-1) to (I-6).

[ chemical formula 8]

[ in the formulae (I-1) to (I-8),

B ¹ ～B ³⁰ independently of each other, 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 (the substituted amino group and the unsubstituted amino group are defined as above), a chlorine atom or a trifluoromethyl group.

n1 to n4 independently represent an integer of 0 to 3.

When n1 is 2 or more, a plurality of B ² May be the same as or different from each other,

when n2 is not less than 2, the catalyst,multiple B ⁶ May be the same as or different from each other,

when n3 is 2 or more, a plurality of B ⁹ May be the same as or different from each other,

when n4 is 2 or more, a plurality of B ¹⁴ May be the same as or different from each other.]

As the anthraquinone pigment, a compound represented by the formula (I-9) is preferable.

[ chemical formula 9]

In the formula (I-9),

R ¹ ～R ⁸ independently of one another, 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.]

As the oxazinone pigment, a compound represented by the formula (I-10) is preferable.

[ chemical formula 10]

In the formula (I-8),

R ⁹ ～R ¹⁵ independently of one another, represent a hydrogen atom, -R ^x 、-NH ₂ 、-NHR ^x 、-NR ^x ₂ 、-SR ^x Or a halogen atom.

As the acridine dye, a compound represented by the formula (I-11) is preferable.

[ chemical formula 11]

In the formula (I-11),

R ¹⁶ ～R ²³ independently of one another, represent a hydrogen atom, -R ^x 、-NH ₂ 、-NHR ^x 、-NR ^x ₂ 、-SR ^x Or a halogen atom.

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

As the cyanine dye, a compound represented by the formula (I-12) and a compound represented by the formula (I-13) are preferable.

[ chemical formula 12]

In the formula (I-12),

D ¹ d (D) ² Independently of each other, a group represented by any one of the formulae (I-12 a) to (I-12 d).

[ chemical formula 13]

n5 represents an integer of 1 to 3. ]

[ chemical formula 14]

In the formula (I-13),

D ³ d (D) ⁴ Independently of each other, a group represented by any one of the formulae (I-13 a) to (1-13 h).

[ chemical formula 15]

n6 represents an integer of 1 to 3. ]

The content of the dichroic dye in the polymerizable liquid crystal composition (a) may be appropriately determined according to the type of the dichroic dye used, and 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, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the dichroic dye is within the above range, the alignment of the polymerizable liquid crystal compound is not easily disturbed, and a polarizing film having a high alignment order can be obtained.

The polymerizable liquid crystal composition (a) may further contain a polymerization initiator. The polymerization initiator is a compound capable of initiating polymerization of the polymerizable liquid crystal compound, and is preferably a photopolymerization initiator in view of initiating polymerization under a relatively low temperature condition. Specifically, a photopolymerization initiator capable of generating a living radical or an acid by the action of light is exemplified, and among them, a photopolymerization initiator capable of generating a radical by the action of light is preferable. The polymerization initiator may be used singly or in combination of two or more.

Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkyl phenone compounds, acyl phosphine oxide compounds, triazine compounds, iodonium salts, sulfonium salts, and the like.

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

Examples of the benzophenone compound include benzophenone, methyl o-benzoyl benzoate, 4-phenylbenzophenone, 4-benzoyl-4 ' -methyldiphenyl sulfide, 3', 4' -tetrakis (t-butylperoxycarbonyl) benzophenone, and 2,4, 6-trimethylbenzophenone.

Examples of the alkylbenzene ketone compound include diethoxyacetophenone, 2-methyl-2-morpholino-1- (4-methylsulfanylphenyl) propan-1-one, 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1, 2-diphenyl-2, 2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1- [ 4- (2-hydroxyethoxy) phenyl ] propan-1-one, 1-hydroxycyclohexylphenyl ketone, and oligomers of 2-hydroxy-2-methyl-1- [ 4- (1-methylvinyl) phenyl ] propan-1-one.

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

Examples of the triazine compound 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) vinyl ] -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- [ 2- (furan-2-yl) vinyl ] -1,3, 5-triazine, 2, 4-bis (trichloromethyl) -6- [ 2- (4-diethylamino-2-methylphenyl) vinyl ] -1,3, 5-triazine, and 2, 4-bis (trichloromethyl) -6- [ 2- (3, 4-dimethoxyphenyl) vinyl ] -1,3, 5-triazine.

The polymerization initiator may be commercially available ones. Examples of the commercially available polymerization initiator include "Irgacure (Irgacure) (registered trademark) 907", "Irgacure (registered trademark) 184", "Irgacure (registered trademark) 651", "Irgacure (registered trademark) 819", "Irgacure (registered trademark) 250", "Irgacure (registered trademark) 369" (Ciba Japan corporation)); "SEIKUOL (registered trademark) BZ", "SEIKUOL (registered trademark) Z", "SEIKUOL (registered trademark) BEE" (from the company of semiengineering, inc.); "kayacure (a registered trademark) BP100" (japan chemical company, ltd.); "kayacure (registered trademark) UVI-6992" (manufactured by DOW Chemical Company); "ADEKA OPTOMER SP-152", "ADEKA OPTOMER SP-170" ((strain) ADEKA); "TAZ-A", "TAZ-PP" (manufactured by Siber Hegner Co., japan); and "TAZ-104" (Sanwa Chemical Co., ltd.) and the like.

When the polymerizable liquid crystal composition (a) contains a polymerization initiator, the content thereof may be appropriately determined according to the type and amount of the polymerizable liquid crystal compound contained in the polymerizable liquid crystal composition (a), and is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the polymerizable initiator is within the above range, the polymerizable liquid crystal compound can be polymerized without disturbing the alignment thereof.

When the polymerizable liquid crystal composition (a) contains a photopolymerization initiator, a photosensitizing agent may be further contained. By using a photosensitizing agent, the polymerization reaction of the polymerizable liquid crystal compound can be further promoted. Examples of the photosensitizing agent include xanthone compounds such as xanthone and thioxanthone (e.g., 2, 4-diethylthioxanthone and 2-isopropylthioxanthone); anthracene compounds such as anthracene and alkoxy group-containing anthracene (e.g., dibutoxyanthracene); phenothiazine, rubrene, and the like. The photosensitizing agent may be used alone or in combination of 2 or more.

The content of the photosensitizing agent in the polymerizable liquid crystal composition (a) may be appropriately determined depending on the type and amount of the photopolymerization initiator and the polymerizable liquid crystal compound, and is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and still more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound.

The polymerizable liquid crystal composition (a) may further contain a leveling agent. The leveling agent has a function of adjusting the fluidity of the polymerizable liquid crystal composition (a) and flattening a coating film obtained by coating the polymerizable liquid crystal composition (a), and specifically, a surfactant is exemplified. The leveling agent is preferably at least 1 kind 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. The leveling agent may be used alone or in combination of 2 or more.

Examples of leveling agents containing polyacrylate compounds as a 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).

As leveling agents containing fluorine atoms as a main component, there may be mentioned, for example, "Megafac (registered trademark) R-08", megafac "R-30", megafac "R-90", megafac "F-410", megafac "F-411", megafac "F-443", megafac "F-445", megafac "F-470", megafac "F-471", megafac "F-477", megafac "F-479", megafac "F-482" and Megafac "F-483" (DIC (Kokai); "Surflon (registered trademark) S-381", surflon "S-382", surflon "S-383", surflon "S-393", surflon "SC-101", surflon "SC-105", "KH-40" and "SA-100" (product of AGC Semi Chemical)); "E1830", "E5844" ((incorporated) institute of great gold precision); "Eftop EF301", "Eftop EF303", "Eftop EF351" and "Eftop EF352" (Mitsubishi material electronic chemical corporation).

The content of the leveling agent in the polymerizable liquid crystal composition (a) is preferably 0.05 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, there is the following tendency: the polymerizable liquid crystal compound is easily oriented horizontally, unevenness is less likely to occur, and a smoother polarizing film can be obtained.

The polymerizable liquid crystal composition (a) may further contain other additives than the polymerization initiator, the photosensitizing agent and the leveling agent. Examples of the other additives include a mold release agent, a stabilizer, a colorant such as a bluing agent, a flame retardant, and a lubricant. When the polymerizable liquid crystal composition (a) contains other additives, the content of the other additives is preferably more than 0% and 20% by mass or less, more preferably more than 0% and 10% by mass or less, relative to the solid content of the polymerizable liquid crystal composition (a).

The polymerizable liquid crystal composition (a) may further contain a solvent. In general, since a compound exhibiting smectic liquid crystallinity has a high viscosity, the addition of a solvent to a polymerizable liquid crystal composition facilitates the application, and as a result, a polarizing film is often easily formed. The solvent may be appropriately selected depending on the solubility of the polymerizable liquid crystal compound and the dichroic dye, and specifically, examples thereof include 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, ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, methyl isobutyl ketone, aliphatic hydrocarbon solvents such as pentane, hexane, heptane, aromatic hydrocarbon solvents such as toluene, xylene, nitrile solvents such as acetonitrile, ether solvents such as tetrahydrofuran, dimethoxyethane, and chlorinated hydrocarbon solvents such as chloroform, chlorobenzene, and the like. These solvents may be used singly or in combination of 2 or more. 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, relative to 100 parts by mass of the solid content constituting the polymerizable liquid crystal composition.

The polymerizable liquid crystal composition (a) can be produced by a conventionally known method for producing a polymerizable liquid crystal composition, and is usually produced by mixing and stirring a polymerizable liquid crystal compound and a dichroic dye, and the above-mentioned additives and solvents, if necessary.

When the polymerizable liquid crystal composition (a) contains a polymerizable liquid crystal compound that exhibits a smectic liquid crystal phase and cures in a horizontally aligned state, a polarizing film that has excellent effect of suppressing photodegradation of a dichroic dye and is less likely to cause a decrease in polarizing performance with time can be obtained from the polymerizable liquid crystal composition (a). In particular, when a polarizing film is formed from a polymerizable liquid crystal composition (a) containing a polymerizable liquid crystal compound which exhibits a smectic liquid crystal phase and is cured in a horizontally aligned state, a polarizing film having a high alignment order can be obtained.

In the case of a polarizing film having a high orientation order, bragg peaks having a higher-order structure such as hexagonal phase and crystalline phase can be obtained in the X-ray diffraction measurement. The bragg peak is a peak derived from a surface periodic structure of molecular orientation. Therefore, in the polarizing film formed from the polymerizable liquid crystal composition of the present invention, the polymerizable liquid crystal compound or the polymer thereof is preferably oriented such that the polarizing film shows a Bragg peak in an X-ray diffraction measurement, more preferably "the molecules of the polymerizable liquid crystal compound are oriented in the direction of absorbing light" Horizontally oriented). In the present invention, the preferred molecular orientation has a face cycle spacing ofIs a polarizing film of (a). The high degree of alignment order such as the bragg peak can be achieved by controlling the kind of the polymerizable liquid crystal compound to be used, the kind of the dichroic dye, the amount thereof, and the like.

The polarizing film in the present invention can be produced, for example, by a method comprising the steps of:

forming a coating film of the polymerizable liquid crystal composition (a);

removing the solvent from the coating film;

after the temperature is raised to a temperature equal to or higher than the temperature at which the polymerizable liquid crystal compound (a) changes phase to a liquid phase, the temperature is lowered to change the polymerizable liquid crystal compound phase to a smectic phase (smectic liquid crystal state); the method comprises the steps of,

the polymerizable liquid crystal compound is polymerized while being maintained in the smectic phase (smectic liquid crystal state).

The formation of the coating film of the polymerizable liquid crystal composition (a) can be performed, for example, by the following means: the polymerizable liquid crystal composition (a) is applied onto a substrate, an alignment film described later, or the like, and particularly the viscosity of the polymerizable liquid crystal composition (a) is adjusted by adding a solvent (hereinafter, also referred to as a "composition for forming a polarizing film"). The composition for forming a polarizing film may be directly applied to a retardation film or other layer constituting the polarizing plate of the present invention.

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

Next, the solvent is removed by drying or the like under the condition that the polymerizable liquid crystal compound contained in the coating film obtained from the composition for forming a polarizing film is not polymerized, whereby a dried coating film can be formed. Examples of the drying method include a natural drying method, a ventilation drying method, a heat drying method, and a reduced pressure drying method.

Further, in order to change the phase of the polymerizable liquid crystal compound (a) into a liquid phase, the temperature is raised to a temperature equal to or higher than the temperature at which the polymerizable liquid crystal compound changes into a liquid phase, and then the temperature is lowered to change the polymerizable liquid crystal compound into a smectic phase (smectic liquid crystal state). The phase transition may be performed after or simultaneously with the removal of the solvent in the coating film.

The polarizing film is formed as a cured layer of the polymerizable liquid crystal composition (a) by polymerizing the polymerizable liquid crystal compound (a) while maintaining the smectic liquid crystal state of the polymerizable liquid crystal compound (a). As the polymerization method, photopolymerization is preferable. In photopolymerization, the light to be irradiated to the dried coating film may be appropriately selected depending on the type of photopolymerization initiator contained in the dried coating film, the type of polymerizable liquid crystal compound (a) (particularly, the type of polymerizable group contained in the polymerizable liquid crystal compound (a)), the amount thereof, and the like. Specific examples thereof include 1 or more light and active electron beams selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α -rays, β -rays and γ -rays. Among them, ultraviolet light is preferable in that the progress of the polymerization reaction is easily controlled, and a device widely used in the art as a photopolymerization device can be used, and the types of the polymerizable liquid crystal compound and the photopolymerization initiator contained in the polymerizable liquid crystal composition are preferably selected in advance so that photopolymerization can be performed by ultraviolet light. In addition, at the time of polymerization, the polymerization temperature may be controlled by performing light irradiation while cooling the dried coating film by an appropriate cooling means. If the polymerization of the polymerizable liquid crystal compound is carried out at a relatively low temperature by using such a cooling means, a polarizing film can be formed appropriately even if a substrate having relatively low heat resistance is used. In the photopolymerization, a patterned polarizing film may be obtained by masking, developing, or the like.

Examples of the light source for the active energy ray include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a xenon lamp, a halogen lamp, a carbon arc lamp, a tungsten lamp, a gallium lamp, an excimer laser, an LED light source that emits light in a wavelength range of 380 to 440nm, 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 3000mW/cm ² . The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activation of the photopolymerization initiator. The time for irradiation of light is usually 0.1 seconds to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and still more preferably 10 seconds to 1 minute. When irradiated 1 or more times with such ultraviolet irradiation intensity, the cumulative light amount thereof is 10 to 3000mJ/cm ² Preferably 50 to 2000mJ/cm ² More preferably 100 to 1000mJ/cm ² 。

Even when the polarizing film is obtained by polymerizing the polymerizable liquid crystal compound (a) while maintaining a smectic liquid crystal state, the effect of the dichroic dye is accompanied with the advantage that the polarizing film has a higher polarizing performance than a conventional bulk guest polarizing film (i.e., a polarizing film formed from a nematic liquid crystal state). In addition, the polarizing film has an advantage of excellent strength as compared with a polarizing film obtained by coating only a dichroic dye or a lyotropic liquid crystal.

The thickness of the polarizing film may be appropriately selected depending on the display device to be used, and is preferably 0.1 to 10. Mu.m, more preferably 0.3 to 4. Mu.m, and still more preferably 0.5 to 3. Mu.m.

The polarizing film is preferably formed on the orientation film. The alignment film is a film having an alignment regulating force for aligning the polymerizable liquid crystal compound (a) in a desired direction. The alignment film preferably has solvent resistance that does not dissolve due to application or the like of the polymerizable liquid crystal compound (a), and heat resistance in heat treatment for removal of the solvent and alignment of the polymerizable liquid crystal compound (a). Examples of the alignment film include an alignment film comprising an alignment polymer, a photo-alignment film, a trench alignment film having a concave-convex pattern and a plurality of trenches on the surface, a stretched film stretched in the alignment direction, and the like, and the photo-alignment film is preferable from the viewpoints of accuracy and quality of the alignment angle.

Examples of the alignment polymer include polyamides having an amide bond in the molecule, gelatins, polyimides having an imide bond in the molecule, polyamic acids as hydrolysates thereof, polyvinyl alcohols, alkyl-modified polyvinyl alcohols, polyacrylamides, polyoxazoles, polyethylenimines, polystyrenes, polyvinylpyrrolidone, polyacrylic acids, and polyacrylates. Among them, polyvinyl alcohol is preferable. The alignment polymer may be used alone or in combination of 2 or more.

An oriented film comprising an oriented polymer can generally be obtained by: a composition obtained by dissolving an oriented polymer in a solvent (hereinafter, sometimes referred to as "oriented polymer composition") is applied to a substrate, and the solvent is removed; alternatively, the alignment polymer composition is applied to a substrate, the solvent is removed, and rubbing (rubbing method) is performed. As the solvent, the same solvents as those exemplified above as solvents that can be used in forming the polarizing film can be mentioned.

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

As the alignment polymer composition, a commercially available alignment film material can be used as it is. Examples of commercially available alignment film materials include SUNEVER (registered trademark, manufactured by Nissan chemical industries, ltd.), OPTOMER (registered trademark, manufactured by JSR, ltd.), and the like.

As a method of applying the orientation polymer composition to the substrate, there can be mentioned the same method as exemplified as a method of applying the composition for forming a polarizing film to the substrate.

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

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

As a method for imparting orientation regulating force by friction method, the following method can be mentioned: the rubbing roller around which the rubbing cloth is wound and rotated is brought into contact with a film of the alignment polymer formed on the surface of the substrate by applying the alignment polymer composition to the substrate and annealing the same.

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

The photoreactive group is a group that generates liquid crystal aligning ability by irradiation with light. Specifically, examples thereof include a group involved in a photoreaction that causes an alignment ability of a liquid crystal, such as an alignment induction or an isomerization reaction, a dimerization reaction, a photocrosslinking reaction, or a photodecomposition reaction of a molecule generated by light irradiation. Among them, a group participating in dimerization reaction or photocrosslinking reaction is preferable in view of excellent orientation. As the photoreactive group, a group having an unsaturated bond, particularly a double bond, is preferable, and a group having at least 1 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 preferable.

Examples of the photoreactive group having a c=c bond include a vinyl group, a polyalkenyl group, a stilbene azole group, a stilbene azolium group, a chalcone group, and a cinnamoyl group.

Examples of the photoreactive group having a c=n bond include a group having a structure such as an aromatic Schiff base or an aromatic hydrazone. Examples of the photoreactive group having n=n bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a disazo group, and a methyl groupA group, and a group having an azobenzene oxide 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 groupsMay 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 group, a haloalkyl group, or the like.

Among them, the photoreactive group involved in the photodimerization reaction is preferable, and the cinnamoyl group and the chalcone group are preferable in terms of the light irradiation amount of the polarized light required for the photoalignment is small, and the photoalignment film excellent in thermal stability and temporal stability is easily obtained. As the polymer having a photoreactive group, a polymer having a cinnamoyl group in which the terminal portion of the side chain of the polymer has a cinnamic acid structure is particularly preferable.

The composition for forming a photo-alignment film is applied to a substrate, whereby a photo-alignment inducing layer can be formed on the substrate. The solvent contained in the composition may be the same as the solvent exemplified above as the solvent that can be used in forming the polarizing film, and may be appropriately selected according to the solubility of the polymer or monomer having a photoreactive group.

The content of the polymer or monomer having a photoreactive group in the composition for forming a photoalignment film may be appropriately adjusted according to the kind of the polymer or monomer and the thickness of the target photoalignment film, and is preferably at least 0.2 mass%, more preferably in the range of 0.3 to 10 mass% relative to the mass of the composition for forming a photoalignment film. The composition for forming a photo-alignment film may contain a polymer material such as polyvinyl alcohol or polyimide and a photosensitizing agent in a range that does not significantly impair the properties of the photo-alignment film.

As a method of applying the composition for forming a photo-alignment film to a substrate, the same method as the method of applying the composition for forming an alignment film to a substrate can be mentioned. Examples of the method for removing the solvent from the composition for forming a photo-alignment film after application include a natural drying method, a ventilation drying method, a heat drying method, and a reduced pressure drying method.

The polarized light may be irradiated directly to a product obtained by removing the solvent from the composition for forming a photo-alignment film applied to the substrate, or may be irradiated by irradiating polarized light from the substrate side and transmitting the polarized light. In addition, the polarized light is particularly preferably substantially parallel light. The wavelength of the irradiated polarized light may be a wavelength in a wavelength region where the photoreactive group of the polymer or monomer having the photoreactive group can absorb light energy. Specifically, UV (ultraviolet) in the wavelength range of 250 to 400nm is particularly preferable. Examples of the light source used for the polarized light irradiation include a xenon lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, ultraviolet light laser such as KrF and ArF, and the like, and more preferably a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp and a metal halide lamp. Among these, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp are preferable because of the high emission intensity of ultraviolet rays having a wavelength of 313 nm. The polarized UV light can be irradiated by passing the light from the above light source through an appropriate polarizer. As the polarizer, a polarizing filter, a polarizing prism of gram-thompson, gram-taylor, or the like, a wire grid type polarizer may be used.

In rubbing or polarized light irradiation, a plurality of regions (patterns) having different directions of alignment of the liquid crystal may be formed by masking.

A groove (oriented film) is a film having a concave-convex pattern or a plurality of grooves (trenches) on the film surface. When a polymerizable liquid crystal compound is applied to a film having a plurality of linear grooves arranged at equal intervals, liquid crystal molecules are aligned in a direction along the grooves.

As a method for obtaining the trench alignment film, the following method can be mentioned: a method in which the surface of a photosensitive polyimide film is exposed through an exposure mask having a slit with a pattern shape, and then developed and rinsed to form a concave-convex pattern; a method of forming a layer of UV curable resin before curing on a plate-like master having grooves on the surface, transferring the formed resin layer to a substrate, and then curing it; and a method in which a roll-shaped master having a plurality of grooves is pushed against a film of a UV curable resin before curing, which is formed on a substrate, to form irregularities, and then the irregularities are cured; etc.

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

The polarizing plate of the present invention can be obtained by laminating a transparent protective film having a thickness of 10 μm to 80 μm on at least one surface of the polarizing film via an adhesive composition. The adhesive composition is not particularly limited, and known adhesives can be used. In the polarizing plate of the present invention, it is preferable that a transparent protective film is laminated on only one surface of the polarizing film.

< transparent protective film >

The transparent protective film is a substrate having transparency capable of transmitting light, particularly visible light, and the transparency is a characteristic that the transmittance with respect to light rays having a wavelength in the range of 380 to 780nm is 80% or more. Specific examples of the transparent protective film include polyolefin such as polyethylene and polypropylene; cyclic olefin resins such as norbornene polymers; polyvinyl alcohol; polyethylene terephthalate; a polymethacrylate; a polyacrylate; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; a polycarbonate; polysulfone; polyether sulfone; polyether ketone; polyphenylene sulfide, polyphenylene oxide, and the like. From the viewpoints of ease of obtaining and transparency, polyethylene terephthalate, polymethacrylate, cellulose ester, cycloolefin resin, or polycarbonate is preferable. Cellulose esters are products obtained by esterifying a part or all of hydroxyl groups contained in cellulose, and are readily available on the market. In addition, cellulose ester substrates are also readily available from the market. Examples of the commercially available cellulose ester base material include "Fujitac Film" (Fujifilm Corporation); "KC8UX2M", "KC8UY", and "KC4UY" (Konica Minolta Opto Products co., ltd.) and the like. Among them, from the viewpoint of balancing the water content, a cycloolefin resin, polyethylene terephthalate, and polycarbonate are preferable, and a cycloolefin resin is more preferable.

The characteristics required for the transparent protective film vary depending on the configuration of the polarizing plate, and in general, a film having as small a retardation as possible is preferable. Examples of the film having the smallest retardation as possible include cellulose ester films having no retardation such as ZeroTAC (Konica Minolta Opta corporation) and Z-TAC (Fujifilm Corporation). In addition, an unstretched cycloolefin resin film is also preferable. The surface of the transparent protective film on which the polarizing film is not laminated may be subjected to a hard coat treatment, an antireflection treatment, an antistatic treatment, or the like.

When the thickness of the transparent protective film is too small, the strength tends to be low and the workability tends to be poor, and therefore, it is usually 10 to 80. Mu.m, preferably 20 to 60. Mu.m, more preferably 20 to 40. Mu.m.

< phase-difference film >

In the present invention, the retardation film preferably satisfies the following formula (1):

100≤Re(550)≤180 (1)

in the formula, re (550) represents the in-plane phase difference value at a wavelength of 550 nm.

When the retardation film has the in-plane retardation value represented by (1), the retardation film functions as a so-called lambda/4 plate. The above formula (1) is preferably 100 nm.ltoreq.Re (550). Ltoreq.180 nm, more preferably 120 nm.ltoreq.Re (550). Ltoreq.160 nm. Re (550) can be measured by the method described in examples.

Further, the retardation film preferably satisfies the following formula (2):

Re(450)/Re(550)<1 (2)

In the formula, re (450) and Re (550) represent the in-plane phase difference values at wavelengths of 450nm and 550nm, respectively.

The retardation film satisfying the above formula (2) has so-called reverse wavelength dispersibility and exhibits excellent polarizing performance. The value of Re (450)/Re (550) is preferably 0.93 or less, more preferably 0.88 or less, further preferably 0.86 or less, preferably 0.80 or more, further preferably 0.82 or more.

The retardation film is generally obtained by polymerizing a polymerizable liquid crystal compound in an aligned state. The polymerizable liquid crystal compound forming the retardation film (hereinafter, also referred to as "polymerizable liquid crystal compound B") refers to a liquid crystal compound having a polymerizable group, particularly a photopolymerizable group. The photopolymerizable group means a group that can participate in polymerization reaction by a living radical, an acid, or the like generated by a photopolymerization initiator. Examples of the photopolymerizable group include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, epoxyethyl, and oxetanyl groups. Among them, preferred are acryloyloxy, methacryloyloxy, vinyloxy, epoxyethyl and oxetanyl groups, more preferred are acryloyloxy and methacryloyloxy, and still more preferred is acryloyloxy. The liquid crystal may be a thermotropic liquid crystal, a lyotropic liquid crystal, a nematic liquid crystal, or a smectic liquid crystal as a phase ordered structure. As the polymerizable liquid crystal compound B, only one kind may be used, or two or more kinds may be used in combination.

The polymerizable liquid crystal compound B is a compound satisfying all of the following (I) to (IV) from the viewpoints of ease of film formation and imparting the characteristics represented by the above formula (Y).

(I) Is a compound having thermotropic liquid crystallinity;

(II) has pi electrons in the long axis direction (a) of the polymerizable liquid crystal compound.

(III) has pi electrons in a direction intersecting with the long axis direction (a) [ intersecting direction (b) ].

(IV) the sum of pi electrons present in the long axis direction (a) is N (pi a), the sum of molecular weights present in the long axis direction is N (Aa), and the pi electron density in the long axis direction (a) of the polymerizable liquid crystal compound is defined by the following formula (i):

D(πa)＝N(πa)/N(Aa) (i)

the total of pi electrons present in the cross direction (b) is denoted as N (pi b), the total of molecular weights present in the cross direction (b) is denoted as N (Ab), and the pi electron density in the cross direction (b) of the polymerizable liquid crystal compound is defined by the following formula (ii):

D(πb)＝N(πb)/N(Ab) (ii)

the relationship between D (pi a) and D (pi b) is 0-1 [ D (pi a)/D (pi b) ].

The nematic phase can be formed by applying all of the polymerizable liquid crystal compounds B satisfying the above (I) to (IV) to an alignment film formed by rubbing treatment and heating to a temperature equal to or higher than the phase transition temperature. The nematic phase formed by aligning the polymerizable liquid crystal compound B is generally aligned such that the long axis directions of the polymerizable liquid crystal compounds are parallel to each other, and the long axis directions are alignment directions of the nematic phase.

The polymerizable liquid crystal compound B having the above-described characteristics generally exhibits inverse wavelength dispersibility in many cases. Specific examples of the compound satisfying the characteristics (I) to (IV) include compounds represented by the following formula (II).

[ chemical formula 16]

The compound represented by the above formula (II) may be used singly or in combination of two or more.

In the formula (II), ar represents a divalent aromatic group which may have a substituent. The aromatic group herein means a group having a planar cyclic structure and having pi electrons of [4n+2] numbers in accordance with the Skoter rule. Here, n represents an integer. When a ring structure is formed by including heteroatoms such as-n=, -S-, etc., the case where the aromatic nature is satisfied by including a pair of non-covalent electrons on these heteroatoms is also included. The divalent aromatic group preferably contains at least 1 or more of nitrogen atom, oxygen atom and sulfur atom.

G ¹ G (G) ² Each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group. The hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group or a nitro group, and the carbon atoms constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be replaced with an oxygen atom, a sulfur atom or a nitrogen atom.

h. i each independently represents an integer of 0 to 3, and satisfies a relationship of 1.ltoreq.h+i. Here, T is when 2.ltoreq.h+i ¹ T and T ² 、G ¹ G (G) ² Each of which may be the same as or different from each other.

E ¹ E and E ² Each independently represents an alkanediyl group having 1 to 17 carbon atoms, wherein hydrogen atoms contained in the alkanediyl group may be substituted with halogen atoms, and wherein-CH is contained in the alkanediyl group ₂ Can be substituted by-O-, -S-, -Si-, -COO-substitution. P (P) ¹ P ² Independently of each other, a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

G ¹ G (G) ² Each independently is preferably 1, 4-phenylene (phenylidenyl) which may be substituted with at least 1 substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, 1, 4-cyclohexanediyl which may be substituted with at least 1 substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably 1, 4-phenylene substituted with a methyl group, unsubstituted 1, 4-phenylene, or unsubstituted 1, 4-trans-cyclohexanediyl, particularly preferably unsubstituted 1, 4-phenylene, or unsubstituted 1, 4-trans-cyclohexanediyl. In addition, a plurality of G's are preferably present ¹ G (G) ² At least 1 of them is a divalent alicyclic hydrocarbon group, and further, more preferably with L ¹ Or L ² Bonded G ¹ G (G) ² At least 1 of them is a divalent alicyclic hydrocarbon group.

L ¹ L and L ² Each independently is preferably-R ^a1 COOR ^a2 -(R ^a1 R is R ^a2 Each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms), more preferably-COOR ^a2-1 -(R ^a2-1 Represents a single bond, -CH ₂ -、-CH ₂ CH ₂ -any one of them), further preferably-COO-or-COOCH ₂ CH ₂ -。

T ¹ T and T ² Each independently is preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a9 OR ^a10 -、-R ^a11 COOR ^a12 -、-R ^a13 OCOR ^a14 -, or R ^a15 OC＝OOR ^a16 -. Here, R is ^a9 ～R ^a16 Each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms. T (T) ¹ T and T ² More preferably each independently is a single bond, -OR ^a10-1 -、-CH ₂ -、-CH ₂ CH ₂ -、-COOR ^a12 ^-1 -, or OCOR ^a14-1 -. Here, R is ^a10-1 、R ^a12-1 、R ^a14-1 Each independently represents a single bond, -CH ₂ -、-CH ₂ CH ₂ -any one of them. T (T) ¹ T and T ² Each independently further preferably is a single bond, -O-, -CH ₂ CH ₂ -、-COO-、-COOCH ₂ CH ₂ -, -OCO-, or OCOCH ₂ CH ₂ -。

From the viewpoint of exhibiting inverse wavelength dispersibility, h and i are preferably in the range of 2.ltoreq.h+i.ltoreq.6, preferably h+i=4, more preferably h=2 and i=2. h=2 and i=2 are more preferable because they have a symmetrical structure.

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

As P ¹ Or P ² Examples of the polymerizable group include an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among these, acryloyloxy, methacryloyloxy, vinyloxy, epoxyethyl and oxetanyl groups are preferable, and acryloyloxy is more preferable.

Ar preferably has at least 1 selected from the group consisting of an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron withdrawing group. Examples of the aromatic hydrocarbon ring include benzene ring, naphthalene ring, and anthracene ring, and benzene ring and naphthalene ring are preferable. Examples of the aromatic heterocycle include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Of these, a thiazole ring, a benzothiazole ring, or a benzofuran ring is preferable, and a benzothiazolyl group is more preferable. When a nitrogen atom is contained in Ar, the nitrogen atom preferably has pi electrons.

In the formula (II), ar represents a total number N of pi electrons contained in the divalent aromatic group _π Preferably 8 or more, more preferably 10 or more, further preferably 14 or more, and particularly preferably 16 or more. The content is preferably 30 or less, more preferably 26 or less, and even more preferably 24 or less.

Examples of the aromatic group represented by Ar include groups represented by the following formulas (Ar-1) to (Ar-23).

[ chemical formula 17]

In the formulae (Ar-1) to (Ar-23), the symbol represents a linking part, Z ⁰ 、Z ¹ Z is as follows ² Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N, N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfonyl group having 1 to 12 carbon atoms, or an N, N-dialkylsulfamoyl group having 2 to 12 carbon atoms.

Q ¹ Q and Q ² Each independently represents-CR ^2’ R ^3’ -、-S-、-NH-、-NR ^2’ -, -CO-or O-, R ^2’ R is R ^3’ Each independently of the groundA hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J ¹ J ² Each independently represents a carbon atom, or a nitrogen atom.

Y ¹ 、Y ² Y and Y ³ Each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may be substituted.

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

As Y ¹ 、Y ² Y and Y ³ Examples of the aromatic hydrocarbon group in (a) include aromatic hydrocarbon groups having 6 to 20 carbon atoms such as phenyl, naphthyl, anthryl, phenanthryl and biphenyl, and preferably phenyl and naphthyl, more preferably phenyl. Examples of the aromatic heterocyclic group include an aromatic heterocyclic group having 4 to 20 carbon atoms and containing at least 1 heteroatom such as a nitrogen atom, an oxygen atom, and a sulfur atom, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridyl group, a thiazolyl group, and a benzothiazolyl group, and a furyl group, a thienyl group, a pyridyl group, a thiazolyl group, and a benzothiazolyl group are preferable.

Y ¹ Y and Y ² Each independently may be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted. Polycyclic aromatic hydrocarbon groups refer to condensed polycyclic aromatic hydrocarbon groups or groups derived from an aromatic ring set. Polycyclic aromatic heterocyclic groups refer to fused polycyclic aromatic heterocyclic groups, or groups derived from an aromatic ring set.

Z ⁰ 、Z ¹ Z is as follows ² Each independently is preferably a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkoxy group having 1 to 12 carbon atoms, Z ⁰ More preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, and Z ¹ Z is as follows ² Further preferred are a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group and a cyano group.

Q ¹ Q and Q ² preferably-NH-, -S-, -NR ^2’ -、-O-，R ^2’ Preferably a hydrogen atom. Wherein,, particularly preferred are-S-; -O-, -NH-.

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

In the formulae (Ar-17) to (Ar-23), Y ¹ To which nitrogen atoms, Z, may be bound ⁰ Together forming an aromatic heterocyclic group. Examples of the aromatic heterocyclic group include aromatic heterocyclic groups which may be contained in Ar and are described above, and examples thereof include pyrrole rings, imidazole rings, pyrroline rings, pyridine rings, pyrazine rings, pyrimidine rings, indole rings, quinoline rings, isoquinoline rings, purine rings, pyrrolidine rings, and the like. The aromatic heterocyclic group may have a substituent. In addition, Y ¹ To which nitrogen atoms, Z, may be bound ⁰ Together form the above-mentioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. For example, a benzofuran ring, benzothiazole ring, benzoxazole ring, and the like can be cited. The compound represented by the formula (II) can be produced, for example, by the method described in JP-A2010-31223.

The content of the polymerizable liquid crystal compound (B) in the polymerizable liquid crystal composition (B) constituting the retardation film is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, and more preferably 90 to 98 parts by mass, relative to 100 parts by mass of the solid content of the polymerizable liquid crystal composition (B). When the content is within the above range, the orientation of the retardation film tends to be high. The solid content herein refers to the total amount of components remaining after volatile components such as solvents are removed from the polymerizable liquid crystal composition (B).

The polymerizable liquid crystal composition (B) may contain a polymerization initiator for initiating the polymerization reaction of the polymerizable liquid crystal compound B. As the polymerization initiator, the same polymerization initiators as exemplified above as the polymerization initiator usable in the polymerizable liquid crystal composition (a) can be mentioned. The polymerizable liquid crystal composition (B) may contain a photosensitizing agent, a leveling agent, an additive exemplified as an additive contained in the polymerizable liquid crystal composition (a), and the like as needed. Examples of the photosensitizing agent and the leveling agent include those similar to those exemplified above as the photosensitizing agent and the leveling agent that can be used in the polymerizable liquid crystal composition (a).

The retardation film can be obtained by the following method: a composition prepared by adding a solvent to a polymerizable liquid crystal composition (B) containing a polymerizable liquid crystal compound B and, if necessary, a polymerization initiator, an additive, and the like (hereinafter, also referred to as a "composition for forming a retardation film") is applied to a substrate or an alignment film, the solvent is removed by drying, and the polymerizable liquid crystal compound B in the obtained coating film is cured by heating and/or active energy rays. Examples of the substrate and/or orientation film that can be used for producing the retardation film include the same substrate and/or orientation film as those exemplified above as the substrate and/or orientation film that can be used for producing the polarizing film.

The solvent used in the composition for forming a retardation film, the method of applying the composition for forming a retardation film, the curing conditions by active energy rays, and the like are the same as those used in the method for producing a polarizing film described above.

The thickness of the retardation film may be appropriately selected depending on the display device to be used, and is preferably 0.1 to 10. Mu.m, more preferably 1 to 5. Mu.m, and still more preferably 1 to 3. Mu.m, from the viewpoints of thinning and bendability.

< circular polarizing plate >

The circularly polarizing plate of the present invention is preferably formed by laminating the above-described polarizing plate and retardation film, and the above-described polarizing plate is preferably formed by laminating a transparent protective film, an alignment film (in particular, a photo-alignment film) and a polarizing film in this order. In the circularly polarizing plate of the present invention, it is preferable that a transparent protective film is laminated on only one surface of the polarizing film, and it is further preferable that the polarizing film and the retardation film are laminated.

The circularly polarizing plate of the present invention may further include other layers (protective layer, adhesive layer, etc.) in addition to the polarizing plate and the retardation film.

In the circularly polarizing plate of the present invention, the polarizing film and the retardation film may be bonded via an adhesive layer or an adhesive layer, or the composition for forming a retardation film may be directly applied to the polarizing film to directly form the retardation film on the polarizing film of the present invention.

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

The thickness of the circularly 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.

< display device >

The present application includes a display device including the circularly polarizing plate of the present application.

The display device of the present application can be obtained by bonding the polarizing film or polarizing plate of the present application to the surface of the display device via an adhesive layer, for example. The circular polarizing plate of the present application can further exhibit the effect when the circular polarizing plate has a structure in which both surfaces of the circular polarizing plate have a hydrophobic base material. The hydrophobic substrate means, for example, a substrate having a moisture permeability of 10g/m ² D (40 ℃ C. 90% RH) (JISK 7129) or less.

The type of the hydrophobic substrate is not particularly limited, and examples thereof include glass.

The display device is a device having a display mechanism, and includes a light emitting element or a light emitting device as a light emitting source. Examples of the display device include a liquid crystal display device, an organic Electroluminescence (EL) display device, an inorganic Electroluminescence (EL) display device, a touch panel display device, an electron emission display device (a field emission display device (FED), a surface conduction field emission display device (SED)), electronic paper (a display device using electronic ink or an electrophoretic element), a plasma display device, a projection display device (a Grating Light Valve (GLV) display device, a display device having a Digital Micromirror Device (DMD), and a piezoelectric ceramic display device).

The liquid crystal display device includes all of a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, a projection liquid crystal display device, and the like. These display devices may be display devices that display two-dimensional images, or may be stereoscopic display devices that display three-dimensional images. In particular, the display device of the present invention is preferably an organic EL display device or a touch panel display device, and particularly preferably an organic EL display device.

Examples

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

Example 1

< production of polarizing plate >

[ polarizing plate: production of polarizing plate comprising polarizing film formed of stretched film

A polyvinyl alcohol film having a thickness of 30 μm (average polymerization degree of about 2400 and saponification degree of 99.9 mol% or more) was uniaxially stretched to about 5 times by dry stretching, and then immersed in pure water at 40 ℃ for 40 seconds while maintaining a tension state. Then, the resultant was immersed in an aqueous dyeing solution having a mass ratio of iodine/potassium iodide/water of 0.044/5.7/100 at 28℃for 30 seconds to carry out dyeing treatment.

Then, the mixture was immersed in an aqueous boric acid solution having a mass ratio of potassium iodide/boric acid/water of 11.0/6.2/100 at 70℃for 120 seconds. Then, after washing with pure water at 8℃for 15 seconds, the film was dried at 60℃for 50 seconds while being held under 300N tension, and then dried at 75℃for 20 seconds, to obtain a polarizer having an iodine adsorption orientation of 12 μm in thickness of the polyvinyl alcohol film.

An aqueous adhesive was injected between the obtained polarizer and cycloolefin film (ZF 14 manufactured by Japanese Zeon Co., ltd.) and bonded by a nip roll. The resulting laminate was dried at 60℃for 2 minutes while maintaining a tension of 430N/m, to obtain a polarizing plate I having a cycloolefin film as a transparent protective film on one side. The aqueous adhesive was prepared by adding 3 parts of carboxyl group-modified polyvinyl alcohol (KURARAY POVAL KL318; manufactured by KURARAY corporation) and 1.5 parts of water-soluble polyamide epoxy Resin (aqueous solution having a solid content concentration of 30% manufactured by sumiriz Resin 650;Sumika Chemtex corporation) to 100 parts of water.

< equilibrium Water content of polarizing plate at 23 ℃ and 50)

The test piece (size: width 4cm, length 10 cm) of the polarizing plate was kept in a clean room at 23℃and relative humidity 50% for 1 day to measure the weight, and then the test piece was dried at 105℃for 1 hour to measure the weight, and the equilibrium water content at 23℃and relative humidity 50% was measured by using model Mitsubishi Chemical Analytech CA-200. The results are shown in Table 1.

< preparation of retardation film >

[ preparation of composition for Forming photo-alignment film ]

The following photo-alignment material 5 parts (number average molecular weight 28000) and cyclopentanone (solvent) 95 parts were mixed, and the resultant mixture was stirred at 80 ℃ for 1 hour, thereby obtaining a composition for forming a photo-alignment film.

[ chemical formula 18]

[ preparation of polymerizable liquid Crystal composition ]

The polymerizable liquid crystal compound B1 (86.0 parts), the polymerizable liquid crystal compound A1 (14.0 parts), the polyacrylate compound (leveling agent) (BYK-361N; BYK-Chemie) (0.12 parts) and the photopolymerization initiator 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) -1-butanone (Irgacure 369; ciba Specialty Chemicals) (3.0 parts) were mixed to obtain a polymerizable liquid crystal composition (B1) comprising the polymerizable liquid crystal compound B1 and the polymerizable liquid crystal compound A1.

Polymerizable liquid crystal compound B1:

[ chemical formula 19]

Polymerizable liquid crystal compound A1:

[ chemical formula 20]

[ method for producing retardation film ]

A cycloolefin polymer film (COP; ZF-14; manufactured by Japanese Zeon Co., ltd.) was treated 1 time with a corona treatment device (AGF-B10; manufactured by spring motor Co., ltd.) at an output of 0.3kW and a treatment rate of 3 m/min. The composition for forming a photo-alignment film was applied to the corona-treated surface by a bar coater, dried at 80℃for 1 minute, and irradiated with polarized UV light (SPOTCURE SP-7 with polarizer unit; manufactured by Ushio electric Co., ltd.) at 100mJ/cm ² Is subjected to polarized UV light exposure to form an alignment film. The thickness of the obtained alignment film was measured by ellipsometer M-220 (manufactured by Japanese spectroscopic Co., ltd.) and found to be 100nm.

Next, the line of the bar coater was set to #30, and the polymerizable liquid crystal composition B1 was applied to the alignment film at a rate of 50 mm/sec, and dried at 120 ℃ for 1 minute. Next, ultraviolet rays (accumulated light amount at wavelength 313nm under nitrogen atmosphere: 500 mJ/cm) were irradiated from the side of the face coated with the polymerizable liquid crystal composition B1 using a high-pressure mercury lamp (Unicure VB-15201BY-A; manufactured BY Ushio Motor Co., ltd.) ² ) Thus, a laminate of the retardation film a and the cycloolefin polymer film was formed. The thickness of the obtained retardation film A was measured by a laser microscope (LEXT; manufactured by Olympus Co., ltd.) and found to be 2.3. Mu.m.

< preparation of circular polarizing plate >

The polyvinyl alcohol side of the polarizing plate I, the phase difference film a, and the retardation film a side of the laminate of the cycloolefin polymer film, which were produced in the above-described manner, were bonded to each other using an acrylic pressure-sensitive adhesive (colorless transparent, unoriented) so that the angle (θ) between the absorption axis of the polarizing plate I and the slow axis of the retardation film a became 45 °, and then the cycloolefin polymer film of the phase difference film was peeled off to produce a circularly polarizing plate.

< durability test >

The retardation film was laminated with 0.4mm thick glass (manufactured by Corning) on both sides of the retardation film side and the polarizing plate side of the obtained circular polarizing plate via an acrylic pressure-sensitive adhesive (colorless transparent, unoriented), and the retardation value of the retardation film was measured. Then, the resultant was put into a 90℃RH oven for 500 hours, and the phase difference value of the retardation film was measured again to obtain a difference value. The differences in phase difference values are shown in table 1. The durability evaluation is shown in table 1 based on the following criteria.

Durability evaluation

O: the difference is less than 1nm.

Delta: the difference is 1nm or more and less than 10nm.

X: the difference is more than 10nm.

Table 1 shows the constituent materials of the polarizing plate and the main constituent materials of the retardation film.

Example 2

< production of polarizing plate >

[ polarizing plate: production of polarizing plate comprising polarizing film formed of composition containing polymerizable liquid Crystal Compound

(production of composition for Forming alignment layer)

2 parts of a polymer described below and 98 parts of o-xylene were mixed, and the resultant mixture was stirred at 80℃for 1 hour, thereby obtaining a composition for forming an alignment layer as a composition for forming a photo-alignment film.

2 parts of a polymer having a photoreactive group (number average molecular weight: 28000) shown below

[ chemical formula 21]

(production of composition for Forming polarizing layer)

The following components were mixed and stirred at 80℃for 1 hour, thereby obtaining a composition for forming a polarizing layer.

75 parts of polymerizable liquid crystal compound represented by the formula (1-6)

[ chemical formula 22]

25 parts of polymerizable liquid crystal compound represented by the formula (1-7)

[ chemical formula 23]

2.8 parts of a dichromatic pigment (1) shown below

[ chemical formula 24]

2.8 parts of a dichromatic pigment (2) shown below

[ chemical formula 25]

2.8 parts of a dichromatic pigment (3) shown below

[ chemical formula 26]

6 parts of a polymerization initiator shown below

2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) -1-butanone (Irgacure 369; manufactured by Ciba Specialty Chemicals Co., ltd.)

1.2 parts of a leveling agent shown below

Polyacrylate Compound (BYK-361N; BYK-Chemie Co., ltd.)

250 parts of solvent as shown below

Cyclopentanone (CNG)

(production of polarizing plate)

For cellulose triacetate film (TAC; KC2UA; konica Min) as a base material (transparent protective film) layerThe surface of the glass was subjected to corona treatment (AGF-B10, manufactured by Chun electric Co., ltd.). The composition for forming an alignment layer was applied to the surface of the film subjected to corona treatment using a bar coater, and then dried in a drying oven set at 120 ℃ for 1 minute to obtain a coating layer for an alignment layer. Polarized UV light was irradiated at 50mJ/cm using a polarized UV light irradiation apparatus (SPOTCURE SP-7; manufactured by Ushio Motor Co., ltd.) ² The cumulative light amount (313 nm reference) was irradiated onto the alignment layer coating layer to form an alignment layer. The composition for forming a polarizing layer was coated on the obtained alignment layer using a bar coater, and then dried in a drying oven set at 110 ℃ for 1 minute. Then, ultraviolet light (wavelength: 365nm in nitrogen atmosphere, cumulative light amount at wavelength 365 nm: 1000 mJ/cm) was irradiated using a high-pressure mercury lamp (Unicure VB-15201BY-A, manufactured BY Ushio Motor Co., ltd.) ² ) Thus, a polarizing plate in which the polymerizable liquid crystal compound and the dichroic dye were oriented was obtained.

A circularly polarizing plate was produced and evaluated in the same manner as in example 1, except that the polarizing plate was used. The results are shown in Table 1.

Example 3

A polarizing plate and a circular polarizing plate were produced and evaluated in the same manner as in example 2, except that a cycloolefin polymer film (COP; ZF-14; manufactured by japan Zeon corporation) was used as the base material (transparent protective film) layer instead of the cellulose triacetate film. The results are shown in Table 1.

Example 4

A polarizing plate and a circular polarizing plate were produced and evaluated in the same manner as in example 2, except that the following polymerizable compound B2 described in japanese unexamined patent publication No. 2016-81035 was used in place of the polymerizable liquid crystal compound B1 as the retardation film. The results are shown in Table 1.

Polymerizable Compound B2

[ chemical formula 27]

Example 5

A polarizing plate and a circular polarizing plate were produced and evaluated in the same manner as in example 2, except that the following polymerizable compound B3 was used instead of the polymerizable liquid crystal compound B1 as the retardation film. The results are shown in Table 1.

Polymerizable Compound B3

[ chemical formula 28]

Comparative example 1

A polarizing plate and a circular polarizing plate were produced and evaluated in the same manner as in example 1, except that cellulose triacetate films (TAC; KC2UA; manufactured by Konica Minolta corporation) were used as transparent protective films on both sides of the polarizer. The results are shown in Table 1.

Comparative example 2

A polarizing plate and a circular polarizing plate were produced and evaluated in the same manner as in example 1, except that a cellulose triacetate film (TAC; KC2UA; manufactured by Konica Minolta corporation) was used as a protective film of the polarizing plate, a cycloolefin polymer film (COP; ZF-14; manufactured by japan Zeon corporation) was used as the other surface, and a retardation layer was bonded to the cellulose triacetate film side of the polarizing plate. The results are shown in Table 1.

Comparative example 3

A polarizing plate and a circular polarizing plate were produced and evaluated in the same manner as in comparative example 2, except that the same polymerizable liquid crystal compound as in example 4 was used as the polymerizable liquid crystal compound of the retardation film. The results are shown in Table 1.

Comparative example 4

A polarizing plate and a circular polarizing plate were produced and evaluated in the same manner as in comparative example 2, except that the same polymerizable liquid crystal compound as in example 5 was used as the polymerizable liquid crystal compound of the retardation film.

Reference example 1

A polarizing plate and a circular polarizing plate were produced and evaluated in the same manner as in comparative example 1, except that a cycloolefin polymer film (COP; ZD-12; manufactured by Japanese Zeon Co., ltd.) was used as the retardation film. The results are shown in Table 1.

TABLE 1

As is clear from the results of table 1, in examples 1 to 5, the balanced water content at 23 ℃ and 50% (relative humidity) of the polarizing plate was 1.5% or less, and the durability in this case was o and Δ, whereas in comparative examples 1 to 4, in which the balanced water content exceeded 1.5%, the durability was x, and the difference was significant. In reference example 1, when the retardation film was a stretched film (a retardation film containing no polymerizable liquid crystal compound), the durability was good although the equilibrium water content of the polarizing plate exceeded 1.5%. The retardation film is considered to be unaffected by moisture in the polarizing plate.

Claims

1. A circularly polarizing plate comprising a polarizing film comprising a dichroic dye and a transparent protective film having a thickness of 10 μm or more and 80 μm or less, and a phase difference film comprising a cured product of a composition comprising a polymerizable liquid crystal compound B,

The polarizing film further comprises a cured product of a polymerizable liquid crystal compound A having an acryloyloxy group or a methacryloyloxy group as a polymerizable group,

in the polarizing plate, a transparent protective film is laminated on only one surface of a polarizing film,

the phase difference film has a thickness of 5 μm or less,

the polymerizable liquid crystal compound B is a compound having an ester bond in the molecular structure,

the polarizing plate has an equilibrium water content of 1.0 mass% or less at a temperature of 23 ℃ and a relative humidity of 50%.

2. The circularly polarizing plate as claimed in claim 1, wherein the dichroic pigment is an azo pigment.

3. The circularly polarizing plate as claimed in claim 1 or 2, wherein the transparent protective film is a cyclic olefin resin.

4. The circularly polarizing plate as claimed in any one of claims 1 to 3, wherein the polarizing film exhibits a bragg peak in an X-ray diffraction measurement.

5. The circularly polarizing plate as claimed in any one of claims 1 to 3, wherein the cured product of the polymerizable liquid crystal compound a exhibits a smectic liquid crystal phase and is cured in a horizontally aligned state.

6. The circularly polarizing plate as claimed in any one of claims 1 to 5, wherein the retardation film satisfies the following formula (1),

100nm≤Re(550)≤180nm(1)

In the formula (1), re (550) represents the in-plane phase difference value at a wavelength of 550 nm.

7. The circularly polarizing plate as claimed in any one of claims 1 to 6, wherein the retardation film satisfies formula (2),

Re(450)/Re(550)<1(2)

in the formula (2), re (450) and Re (550) represent in-plane phase difference values at wavelengths of 450nm and 550nm, respectively.

8. The circularly polarizing plate as claimed in any one of claims 1 to 7, wherein the slow axis of the retardation film makes an angle of substantially 45 ° with the absorption axis of the polarizing film.

9. The circularly polarizing plate as claimed in any one of claims 1 to 8, wherein the polymerizable liquid crystal compound B has at least one polymerizable group selected from the group consisting of an acryloyloxy group and a methacryloyloxy group.

10. The circularly polarizing plate as claimed in any one of claims 1 to 9, wherein the polymerizable liquid crystal compound B is a compound represented by the following formula (II),

[ chemical formula 1]

In the formula (II) of the present invention,

ar represents a divalent aromatic group which may have a substituent;

G ¹ g (G) ² Each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group;

L ¹ l and L ² Each independently is a divalent linking group having an ester structure;

T ¹ t and T ² Each independently is a single bond or a divalent linking group;

h and i each independently represent an integer of 0 to 3, satisfying the relationship of 1.ltoreq.h+i; here, T is when 2.ltoreq.h+i ¹ T and T ² 、G ¹ G (G) ² Each of which may be the same as or different from each other;

E ¹ e and E ² Each independently represents an alkanediyl group having 1 to 17 carbon atoms, wherein hydrogen atoms contained in the alkanediyl group may be substituted with halogen atoms, -CH contained in the alkanediyl group ₂ -can be replaced by-O-, -S-, -COO-, in which case there are a plurality of-O-, -S-, -COO-, which are not adjacent to each other;

11. An organic EL display device comprising the circularly polarizing plate as claimed in any one of claims 1 to 10.