CN113302528A

CN113302528A - Circularly polarizing plate and organic EL display device using the same

Info

Publication number: CN113302528A
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: 2021-08-24
Anticipated expiration: 2040-02-06
Also published as: TW202040181A; JP2020134934A; WO2020166476A1; KR20210127704A; CN113302528B

Abstract

The present invention provides a circular polarizing plate comprising a polarizing film comprising a dichroic pigment and a transparent protective film having a thickness of 10 [ mu ] m or more and 80 [ mu ] m or less laminated together, and a phase difference film which is a cured product of a composition comprising a polymerizable liquid crystal compound B, wherein the phase difference film has a thickness of 5 [ mu ] m or less, the polymerizable liquid crystal compound B is a compound having an ester bond in a molecular structure, and the polarizing plate has an equilibrium water content of 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 the 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 spread of thin displays, displays (organic EL display devices) having organic EL panels mounted thereon have spread. In the organic EL panel, there is a problem that clear black display cannot be obtained because external light is reflected at the internal metal electrode. In order to solve this problem, by providing the circularly polarizing plate on the viewing surface, external light reflection can be suppressed. That is, as the lamination order from the viewer, circular polarizing plate → organic EL display. The circularly polarizing plate can be generally produced by laminating a polarizing plate and a retardation film. As the polarizing plate, a polarizing plate obtained by laminating a transparent protective film on a polarizing plate 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 can be used. In this case, a λ/4 plate exhibiting a property (reverse wavelength dispersion characteristic) that the birefringence increases with increasing wavelength can be preferably used.

Disclosure of Invention

Problems to be solved by the invention

In an organic EL display device, there is a problem that an organic EL layer deteriorates due to oxygen and moisture depending on the use environment and becomes non-luminous, and both surfaces of an organic EL panel are sometimes protected with a base material having low moisture permeability such as glass. The outermost surface of the panel may be protected with a water-resistant surface or a substrate having low moisture permeability. However, such a structure is known to have a problem that the color changes in a high-temperature environment depending on the type of retardation film. As a result of intensive studies, the inventors of the present application have found that a slight amount of moisture contained in a protective film forming a polarizing plate, polyvinyl alcohol, or the like 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 invention is to provide an excellent circularly polarizing plate with a small color change in a high-temperature environment, and an organic EL display device with the circularly polarizing plate.

Means for solving the problems

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

[1] A circularly polarizing plate comprising a polarizing film comprising a dichroic pigment and a transparent protective film having a thickness of 10 to 80 μm laminated together, and a phase difference film which is 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 according to [1], wherein the dichroic pigment is an azo pigment.

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

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

[6] The circularly polarizing plate according to [4], wherein a 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 according to any one of [1] to [6], wherein the retardation film satisfies the following formula (1).

100≤Re(550)≤180 (1)

[ in the formula, Re (550) represents an in-plane retardation value at a wavelength of 550 nm. ]

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

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

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

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

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

[11] The circularly polarizing plate according to 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), the compound is shown in the specification,

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

G¹And G²Each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group.

L¹And L²Each independently is a divalent linking group having an ester structure.

T¹And T²Each independently is a single bond or a divalent linking group.

h and i independently represent an integer of 0 to 3, and satisfy the relationship of 1. ltoreq. h + i. Here, when 2. ltoreq. h + i, T¹And T²、G¹And G²Each may be the same as or different from each other.

E¹And E²Each independently represents an alkanediyl group having 1 to 17 carbon atoms, wherein a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and-CH contained in the alkanediyl group₂May be replaced by-O-, -S-, -COO-, and when there are a plurality of-O-, -S-, -COO-, they do not adjoin each other.

P¹And P²Independently represent a polymerizable group or a hydrogen atom, and at least one is polymerizedA sex group.

[12] The circularly polarizing plate according to 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 according to 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, the equilibrium moisture content of the polarizing plate at a temperature of 23 ℃ and a humidity of 50% needs to be controlled to 1.5% by mass or less. Equilibrium moisture content is defined as: in air of a certain temperature and humidity, the moisture content in the material reaches the moisture content in a state of equilibrium in the atmosphere. In the present invention, a polarizing plate (size: width: 4cm, length: 10cm) 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, and then the polarizing plate was dried at 105 ℃ for 1 hour to measure the mass, and the value obtained was calculated by the following formula as the equilibrium moisture content:

(mass at 23 ℃ and 50% relative humidity-mass after drying at 105 ℃ for 1 hour) ÷ (mass at 23 ℃ and 50% relative humidity) × 100

In the present invention, when the equilibrium moisture content of the polarizing plate is more than 1.5% by mass, the color of the circularly polarizing plate at high temperature is likely to change, which is not preferable. The equilibrium moisture content of the polarizing plate is preferably 1.0 mass% or less, and 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 moisture content of the polarizing plate is higher than 1.5% by mass, the equilibrium moisture content can be reduced by drying. Drying may be suitably performed by, for example, leaving the mixture in a dry environment, in addition to heating.

The circularly polarizing plate of the present invention comprises a polarizing plate comprising a polarizing film containing a dichroic dye and a transparent protective film having a thickness of 10 μm or more and 80 μm or less laminated together, and a phase difference film which is a cured product of a composition containing a polymerizable liquid crystal compound B.

< polarizing film >

The polarizing film is a film having a function of light absorption anisotropy. The polarizing film may be a stretched film having a dichroic pigment adsorbed thereon, or may be a cured product of a composition containing a horizontally oriented polymerizable liquid crystal compound and a horizontally oriented dichroic pigment. From the viewpoint of the equilibrium 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 dichroic pigment adsorbed thereon as a polarizing film can be generally produced through the following steps: a step of uniaxially stretching a polyvinyl alcohol resin film; a step of staining the polyvinyl alcohol resin film with a dichroic pigment to thereby adsorb the dichroic pigment; treating the dichroic pigment-adsorbed polyvinyl alcohol resin film with an aqueous boric acid solution; and a step of washing the substrate 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-based resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable therewith may be used. 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%, and 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, and preferably 1,500 to 5,000.

A film made of such a polyvinyl alcohol resin can be used as a polarizing film blank (Japanese-Kokai: Yuanqi フイル ). The method for forming the film from the polyvinyl alcohol resin is not particularly limited, and the film can be formed by a known method. The thickness of the polyvinyl alcohol base film may be, for example, about 10 to 150 μm.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before, simultaneously with, or after the dyeing with the dichroic pigment. In the case of performing 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 at a plurality of stages among them. In the case of uniaxial stretching, the uniaxial stretching may be performed between rolls having different peripheral speeds, or the uniaxial stretching may be performed using a hot roll. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which stretching is performed in a state where the polyvinyl alcohol resin film is swollen with a solvent. The draw ratio is usually about 3 to 8 times.

The dichroic dye-based dyeing of the polyvinyl alcohol resin film can be performed, for example, by a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye.

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

When iodine is used as the dichroic dye, 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) 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 to dye the resin film is generally used.

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

The boric acid treatment after dyeing with the dichroic pigment can be usually performed by a method of 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 dichroic dye, 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, per 100 parts by mass of water. The time for immersing in the aqueous solution of boric acid 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 ℃.

Usually, the polyvinyl alcohol resin film after the boric acid treatment is subjected to a water washing treatment. The water washing treatment can be performed, for example, by a method of 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 dipping time is usually about 1 to 120 seconds.

The polarizing film can be obtained by performing a drying treatment after water washing. The drying treatment can be performed using, for example, a hot air dryer or a far infrared heater. The temperature of the drying treatment 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. The moisture content of the polarizer can be reduced to a practical level by the drying treatment. The water content is usually about 5 to 20 mass%, preferably 8 to 15 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. If the moisture content is higher than 20% by 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 comprising a cured product of a composition comprising a horizontally oriented polymerizable liquid crystal compound and a horizontally oriented dichroic pigment (hereinafter, sometimes 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 when mixed with the dichroic pigment, a thermotropic liquid crystal is preferred. In the case of the thermotropic liquid crystal, the thermotropic liquid crystal compound may exhibit 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 crystallinity (hereinafter, also referred to as "polymerizable liquid crystal compound (a)"). By using a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity, a polarizing film having a high degree of alignment order can be formed.

The liquid crystal state exhibited by the polymerizable liquid crystal compound (a) is preferably a smectic phase (smectic liquid crystal state), and more preferably a higher order smectic phase (higher order smectic liquid crystal state) from the viewpoint of enabling a higher degree of alignment order. Here, the higher order smectic phase 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 them, smectic B phase, smectic F phase and smectic I phase are more preferable. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, but a thermotropic liquid crystal is preferable in terms of enabling precise film thickness control. The polymerizable liquid crystal compound may be a monomer, or 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 a polymerization reaction by an active radical, an acid, or the like generated from a polymerization initiator. Examples of the polymerizable group of the polymerizable liquid crystal compound (A) include a vinyl group, a vinyloxy group, a 1-chloroethenyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an epoxyethyl group, and an oxetanyl group. Among these, radical polymerizable groups are preferable, acryloxy groups, methacryloxy groups, vinyl groups, and vinyloxy groups are more preferable, and acryloxy groups and methacryloxy groups are even 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 a compound represented by the following formula (a1) (hereinafter, also referred to as "polymerizable liquid crystal compound (a 1)").

U¹-V¹-W¹-(X¹-Y¹-)_n-X²-W²-V²-U² (A1)

[ in the formula (A1),

X¹and X²Independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein the hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted by 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 orNitro group, and the carbon atom 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. Preferably, X¹And X²At 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.

Y¹Is a single bond or a divalent linking group.

n is 1 to 3, when n is 2 or more, plural X¹May be the same as or different from each other. X²Can be associated with a plurality of X¹Any or all of them may be the same or different. When n is 2 or more, plural Y¹May be the same as or different from each other. From the viewpoint of liquid crystallinity, n is preferably 2 or more.

U¹Represents a hydrogen atom or a (meth) acryloyloxy group.

U²Represents a (meth) acryloyloxy group.

W¹And W²Independently of one another, a single bond or a divalent linking group.

V¹And V²Independently represent an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and-CH constituting the alkanediyl group₂-may be replaced by-O-, -CO-, -S-or NH-.]

In the polymerizable liquid crystal compound (A1), X¹And X²Preferred are, independently of one another, a1, 4-phenylene group which may have a substituent, or a cyclohexane-1, 4-diyl group which may have a substituent, X¹And X²At 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, preferably a trans-cyclohexane-1, 4-diyl group. Examples of the optionally substituted 1, 4-phenylene group which may have a substituent or the optionally substituted cyclohexane-1, 4-diyl group 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 halogen atom such as a chlorine atom and a fluorine atom. Preferably unsubstituted.

The polymerizable liquid crystal compound (A1) is preferably a moiety [ hereinafter referred to as a partial structure (A1-1) ] represented by the formula (A1-1) in the formula (A1) from the viewpoint of easily exhibiting smectic liquid crystallinity. The (c) is an asymmetric structure.

-(X¹-Y¹-)_n-X²- (A1-1)

[ in the formula, X¹、Y¹、X²And n each represents the same meaning as described above. Angle (c)

As the polymerizable liquid crystal compound (A1) having an asymmetric partial structure (A1-1), there may be mentioned, for example, a polymerizable liquid crystal compound in which n is 1 and 1X is¹And X²A polymerizable liquid crystal compound (A1) having a structure different from each other. In addition, there may be mentioned: n is 2 and 2Y¹A polymerizable liquid crystal compound (A1) having the same structure, wherein 2X' s¹Are of the same structure as each other, 1X²Is equal to the 2X¹A different structure; 2X¹And W in¹Bonded X¹Is related to another X¹And X²A different structure, and another X¹And X²A polymerizable liquid crystal compound (A1) having the same structure. Further, n is 3 and 3Y¹A polymerizable liquid crystal compound (A1) having the same structure, wherein 3X' s¹And 1X²Any one of them is a structure different from the other 3.

Y¹Is preferably-CH₂CH₂-、-CH₂O-、-CH₂CH₂O-, -COO-, -OCOO-, single bond, -N ═ N-, -CR^a＝CR^b-、-C≡C-、-CR^aN-or-CO-NR^a-。R^aAnd R^bIndependently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y is¹More preferably-CH₂CH₂-, -COO-or single bonds, with a plurality of Y's present¹In the case of (2), with X²Bonded Y¹More preferably-CH₂CH₂-or-CH₂O-。X¹And X²When all of the Y atoms have the same structure, it is preferable that 2 or more Y atoms different from each other in bonding form are present¹. There are a plurality of Y's different in bonding pattern from each other¹In the case of (b), the structure is asymmetric, and thus smectic liquid crystallinity tends to be easily exhibited.

U²Is (meth) acryloyloxy. U shape¹Is a hydrogen atom or a (meth) acryloyloxy group, preferably a (meth) acryloyloxy group. From the viewpoint of improving the interlayer adhesiveness and heat resistance of the polarizing film, U is preferable¹And U²Are all (meth) acryloyloxy. The (meth) acryloyloxy group may be in a polymerized state or in an unpolymerized state, and is preferably in an unpolymerized state.

As V¹And V²Examples of the alkanediyl group include a methylene group, an ethylene group, a propane-1, 3-diyl group, a butane-1, 4-diyl group, a pentane-1, 5-diyl group, a hexane-1, 6-diyl group, a heptane-1, 7-diyl group, an octane-1, 8-diyl group, a decane-1, 10-diyl group, a tetradecane-1, 14-diyl group, and an eicosane-1, 20-diyl group. V¹And V²Preferably an alkanediyl group having 2 to 12 carbon atoms, and more preferably an alkanediyl group having 6 to 12 carbon atoms.

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

W¹And W²Independently of one another, is 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 formulae (a-a) to (a-i) and showing smectic liquid crystallinity. From the viewpoint of easily exhibiting higher order smectic liquid crystallinity, the compound more preferably has a structure represented by the formula (A-a), the formula (A-b) or the formula (A-c). In the formulae (A-a) to (A-i), the bond represents a 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-isomer.

[ chemical formula 3]

[ chemical formula 4]

[ chemical formula 5]

[ chemical formula 6]

[ chemical formula 7]

Among these, at least one selected from the group consisting of compounds represented by the formula (A-2), the formula (A-3), the formula (A-4), the formula (A-5), the formula (A-6), the formula (A-7), the formula (A-8), the formula (A-13), the formula (A-14), the formula (A-15), the formula (A-16) and the formula (A-17) is preferable. The polymerizable liquid crystal compound (a1) may be used alone in 1 kind, or two or more kinds may be used in combination.

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) by Lub et al, or Japanese patent No. 4719156, etc.

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

When 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 (a 1). By combining a plurality of polymerizable liquid crystal compounds, the liquid crystal properties can be temporarily maintained even at a temperature not higher than the liquid crystal-to-crystal transition temperature in some cases.

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 still 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 alignment of the polymerizable liquid crystal compound tends to be high. In the present specification, the solid content means 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 is a dye having a property that the absorbance of molecules in the major axis direction is different from the absorbance of molecules in the minor axis direction. The dichroic pigment is a pigment that exhibits dichroism by being aligned with a liquid crystal compound, and may have polymerizability or liquid crystal properties. The dichroic dye that can be used in the present invention is not particularly limited, and may be a dye or a pigment as long as it has the above properties. In addition, 2 or more kinds of dyes or pigments may be used in combination, or a dye and a pigment may be used in combination.

The dichroic dye preferably has a maximum absorption wavelength (lambda) in the range of 300 to 700nm_MAX) The dichroic dye of (4). Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes.

Examples of the azo dye include monoazo dyes, disazo dyes, trisazo dyes, tetraazo dyes, and stilbene azo dyes, and the disazo dyes and the trisazo dyes are preferable, and examples thereof include compounds represented by the formula (I) (hereinafter, also referred to as "compound (I)").

K¹(-N＝N-K²)_p-N＝N-K³ (I)

[ in the formula (I), K¹And K³Independently of each other, represents 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. K²Represents a p-phenylene group which may have a substituent, a naphthalene-1, 4-diyl group 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 K²May be the same or different from each other. In the range where absorption is exhibited in the visible light region, the-N ═ N-bond may be replaced by-C ═ C-, -COO-, -NHCO-, -N ═ CH-bond.]

Examples of the monovalent heterocyclic group include groups 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 groups obtained by removing 2 hydrogen atoms from the above-mentioned heterocyclic compound.

As K¹And K³In (1) phenyl, naphthyl and monovalent heterocyclic group, and K²The substituent optionally contained in the p-phenylene group, naphthalene-1, 4-diyl group and divalent heterocyclic group in (1) includes an alkyl group having 1 to 4 carbon atoms; alkoxy groups having 1 to 4 carbon atoms such as methoxy, ethoxy, butoxy and the like; a fluorinated alkyl group having 1 to 4 carbon atoms such as a trifluoromethyl group; a cyano group; a nitro group; a halogen atom; a substituted or unsubstituted amino group such as an amino group, a diethylamino group, or a pyrrolidinyl group (the substituted amino group means an amino group having 1 or 2 alkyl groups having 1 to 6 carbon atoms or an amino group in which 2 substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms; the unsubstituted amino group is-NH₂. ) And the like.

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

[ chemical formula 8]

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

B¹～B³⁰independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of the substituted amino group and the unsubstituted amino group are as described above), a chlorine atom or a trifluoromethyl group.

n1 to n4 each independently represents an integer of 0 to 3.

When n1 is 2 or more, a plurality of B²May be the same as or different from each other,

when n2 is 2 or more, a plurality of B⁶May be the same as or different from each other,

when n3 is 2 or more, a plurality of B⁹May be the same as or different from each other,

when n4 is 2 or more, a plurality of B¹⁴May be the same or different from each other.]

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

[ chemical formula 9]

[ in the formula (I-9),

R¹～R⁸independently of one another, represents a hydrogen atom, -R^x、-NH₂、-NHR^x、-NR^x ₂、-SR^xOr a halogen atom.

R^xRepresents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.]

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

[ chemical formula 10]

[ in the formula (I-8),

R⁹～R¹⁵independently of one another, represents a hydrogen atom, -R^x、-NH₂、-NHR^x、-NR^x ₂、-SR^xOr a halogen atom.

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

[ chemical formula 11]

[ in the formula (I-11),

R¹⁶～R²³independently of one another, represents a hydrogen atom, -R^x、-NH₂、-NHR^x、-NR^x ₂、-SR^xOr a halogen atom.

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

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),

D¹and D²Earth surface independent of each otherA group represented by any one of the formulae (I-12a) to (I-12 d).

[ chemical formula 13]

n5 represents an integer of 1 to 3. ]

[ chemical formula 14]

[ in the formula (I-13),

D³and D⁴Independently of each other, represents a group represented by any one of the formulae (I-13a) 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 depending on the kind 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 still more preferably 0.1 to 12 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. When the content of the dichroic dye is within the above range, the orientation of the polymerizable liquid crystal compound is less likely to be disturbed, and a polarizing film having a high degree of orientation 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 the polymerization reaction of the polymerizable liquid crystal compound, and is preferably a photopolymerization initiator in that the polymerization reaction can be initiated at a relatively low temperature. Specifically, a photopolymerization initiator capable of generating an active 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 alone or in combination of two or more.

Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts, 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-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4 ' -methyldiphenyl sulfide, 3 ', 4,4 ' -tetrakis (t-butylperoxycarbonyl) benzophenone, and 2,4, 6-trimethylbenzophenone.

Examples of the alkylphenone compound include diethoxyacetophenone, 2-methyl-2-morpholino-1- (4-methylthiophenyl) propan-1-one, 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1, 2-diphenyl-2, 2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1- [ 4- (2-hydroxyethoxy) phenyl ] propan-1-one, 1-hydroxycyclohexylphenyl ketone and 2-hydroxy-2-methyl-1- [ 4- (1-methylvinyl) phenyl ] propan-1-one Oligomers of alk-1-ones, and the like.

Examples of the acylphosphine oxide compound include 2,4, 6-trimethylbenzoyldiphenylphosphine 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.

As the polymerization initiator, commercially available products can be used. Examples of commercially available polymerization initiators 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 (strain)); "SEIKUOL (registered trademark) BZ", "SEIKUOL (registered trademark) Z", "SEIKUOL (registered trademark) BEE" (fine chemical strain)); "kayacure (カヤキュアー) (registered trademark) BP 100" (japan chemical (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" (Siber Hegner, 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 determined as appropriate depending on the kind 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 still 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, it may further contain a photosensitizer. By using the photosensitizer, 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-containing anthracene (e.g., dibutoxyanthracene); phenothiazine, rubrene, and the like. The photosensitizing agent may be used singly or in combination of 2 or more.

The content of the photosensitizer in the polymerizable liquid crystal composition (a) may be determined as appropriate depending on the kind 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, based on 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) to flatten a coating film obtained by applying the polymerizable liquid crystal composition (a), and specifically includes a surfactant. The leveling agent is preferably at least 1 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 the leveling agent containing a polyacrylate compound 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 Co.).

Examples of the leveling agent containing a fluorine atom-containing compound as a main component include "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 (trademark)); "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" (AGC Semi Chemical (Co.))); "E1830", "E5844" ((strain) Dajin precision chemical research institute); "Eftop EF 301", "Eftop EF 303", "Eftop EF 351" and "Eftop EF 352" (Mitsubishi Material electronics Kabushiki Kaisha).

The content of the leveling agent in the polymerizable liquid crystal composition (a) is preferably 0.05 to 5 parts by mass, and 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, the following tendency is present: the polymerizable liquid crystal compound is easily horizontally aligned, and unevenness is less likely to occur, whereby a smoother polarizing film can be obtained.

The polymerizable liquid crystal composition (a) may further contain other additives in addition to the polymerization initiator, the photosensitizer and the leveling agent. Examples of the other additives include colorants such as a mold release agent, a stabilizer, and 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, based on 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, it is easy to apply the compound by adding a solvent to a polymerizable liquid crystal composition, 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 specific examples thereof include water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, an alcohol solvent such as propylene glycol monomethyl ether, an ester solvent such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ -butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate, a ketone solvent such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone, an aliphatic hydrocarbon solvent such as pentane, hexane, and heptane, an aromatic hydrocarbon solvent such as toluene and xylene, a nitrile solvent such as acetonitrile, an ether solvent such as tetrahydrofuran and dimethoxyethane, and a chlorinated hydrocarbon solvent such as chloroform and chlorobenzene. These solvents may be used alone 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 still more preferably 180 to 600 parts by mass, per 100 parts by mass of the solid components 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 can be usually produced by mixing and stirring a polymerizable liquid crystal compound, 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 which exhibits a smectic liquid crystal phase and is cured in a horizontally aligned state, a polarizing film having an excellent effect of suppressing the photodegradation of a dichroic dye and being less likely to suffer from a decline 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 degree of alignment order can be obtained.

In the polarizing film having a high degree of orientation order, bragg peaks derived from a high-order structure such as a hexagonal phase or a crystal phase can be obtained in the X-ray diffraction measurement. The bragg peak is a peak derived from a plane 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 so that the polarizing film exhibits a bragg peak in X-ray diffraction measurement, and more preferably "horizontal orientation" in which the molecules of the polymerizable liquid crystal compound are oriented in the direction of absorbing light. In the present invention, the plane period interval of the preferred molecular orientation is

The polarizing film of (1). The high degree of alignment order such as the bragg peak can be realized by controlling the kind of the polymerizable liquid crystal compound 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;

heating to a temperature at which the polymerizable liquid crystal compound (a) changes phase to a liquid phase or higher, and then cooling to change the phase of the polymerizable liquid crystal compound to a smectic phase (smectic liquid crystal state); and the number of the first and second groups,

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 carried out, for example, by the following method: a polymerizable liquid crystal composition (a), particularly a polymerizable liquid crystal composition (a) whose viscosity has been adjusted by adding a solvent (hereinafter, also referred to as "composition for forming a polarizing film"), is applied onto a substrate, an alignment film described later, or the like. The polarizing film-forming composition may be applied directly to the retardation film or other layer constituting the polarizing plate of the present invention.

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

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 natural drying, air drying, heat drying, and reduced-pressure drying.

Further, in order to change 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 the removal of the solvent in the coating film, or may be performed simultaneously with the removal of the solvent.

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). The polymerization method is preferably a photopolymerization method. In photopolymerization, the light to be irradiated to the dried coating film may be appropriately selected depending on the kind of photopolymerization initiator contained in the dried coating film, the kind of polymerizable liquid crystal compound (a) (particularly, the kind of polymerizable group contained in the polymerizable liquid crystal compound (a)), the amount of the polymerizable group, and the like. Specific examples thereof include 1 or more kinds of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-ray, α -ray, β -ray and γ -ray, and an active electron beam. Among them, ultraviolet light is preferable from the viewpoint 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 it is preferable that the kinds of the polymerizable liquid crystal compound and the photopolymerization initiator contained in the polymerizable liquid crystal composition are selected in advance so that photopolymerization can be performed by ultraviolet light. In addition, during polymerization, the polymerization temperature may be controlled by irradiating with light while cooling the dried coating film by an appropriate cooling means. When the polymerization of the polymerizable liquid crystal compound is carried out at a relatively low temperature by using such a cooling means, the polarizing film can be appropriately formed even if a substrate having relatively low heat resistance is used. In the photopolymerization, a patterned polarizing film can be obtained by masking, development, or the like.

Examples of the light source of 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 emitting light having 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 10-3000 mW/cm². The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activation of the photopolymerization initiator. The time for irradiating light is usually 0.1 second to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and further preferably 10 seconds to 1 minute. When the ultraviolet irradiation intensity is applied for 1 or more times, the cumulative light quantity is 10 to 3000mJ/cm²Preferably 50 to 2000mJ/cm²More preferably 100 to 1000mJ/cm²。

In the case where the polymerizable liquid crystal compound (a) is polymerized while maintaining a liquid crystal state of a smectic phase, the polarizing film has an advantage of higher polarizing performance than a conventional host guest polarizing film (i.e., a polarizing film formed from a liquid crystal state of a nematic phase) due to the action of the dichroic dye. Further, the polarizing film has an advantage of being superior in strength to a polarizing film formed by applying only a dichroic dye or a lyotropic liquid crystal.

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

The polarizing film is preferably formed on an alignment film. The alignment film is a film having an alignment regulating force for aligning the liquid crystal of the polymerizable liquid crystal compound (a) in a desired direction. The alignment film preferably has solvent resistance that does not dissolve due to application of the polymerizable liquid crystal compound composition (a) or the like, and heat resistance for use in heat treatment for removing the solvent and aligning the polymerizable liquid crystal compound (a). Examples of the alignment film include an alignment film containing an alignment polymer, a photo-alignment film, a groove alignment film having a surface with a concavo-convex pattern and a plurality of grooves, and a stretched film stretched in an alignment direction, and the photo-alignment film is preferable from the viewpoint of accuracy and quality of an alignment angle.

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

The alignment film containing an alignment polymer can be generally obtained by: a method for producing a substrate having a structure in which a composition obtained by dissolving an oriented polymer in a solvent (hereinafter, sometimes referred to as an "oriented polymer composition") is applied to a substrate and the solvent is removed; alternatively, the oriented polymer composition is applied to a substrate, the solvent is removed, and rubbing is performed (rubbing method). Examples of the solvent include the same solvents as those exemplified above as solvents that can be used in forming a polarizing film.

The concentration of the oriented polymer in the oriented polymer composition may be in a range in which the oriented polymer material can be completely dissolved in the solvent, and is preferably 0.1 to 20%, and more preferably about 0.1 to 10% in terms of solid content with respect 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 suniver (registered trademark, manufactured by nippon chemical industry corporation), OPTOMER (registered trademark, manufactured by JSR corporation), and the like.

The method of applying the oriented polymer composition to the substrate may be the same as the method exemplified as the 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 forced air drying method, a heat drying method, a reduced pressure drying method, and the like.

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

Examples of the method for imparting orientation restriction by the rubbing method include the following methods: a rubbing roll wound with a rubbing cloth and rotated is brought into contact with a film of an alignment polymer formed on the surface of a substrate by applying an alignment polymer composition to the substrate and annealing the same.

The photoalignment film may 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 photo alignment film") is applied to a substrate, and then polarized light (preferably polarized UV light) is irradiated thereto. It is more preferable for the photo-alignment film to be able to arbitrarily control the direction of the alignment regulating force by selecting the polarization direction of the polarized light to be irradiated.

The photoreactive group refers to a group that generates liquid crystal alignment ability by light irradiation. Specifically, there may be mentioned groups which participate in photoreaction originating from liquid crystal aligning ability, such as orientation induction or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photolysis reaction of molecules by light irradiation. Among them, a group participating in dimerization reaction or photocrosslinking reaction is preferable from the viewpoint of excellent orientation. As the photoreactive group, a group having an unsaturated bond, particularly a double bond is preferable, and a 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 polyene group, a stilbene group, a stilbenazolyl group, a stilbazolium group, a chalcone group, and a cinnamoyl group.

Examples of the photoreactive group having a C ═ N bond include groups having a structure of an aromatic schiff base, an aromatic hydrazone, or the like. Examples of the photoreactive group having an N ═ N bond include an azophenyl group, an azonaphthyl group, an aromatic heterocyclic azo group, a bisazo group, and a methyl group

A group having an azoxybenzene structure. Examples of the photoreactive group having a C ═ O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, and haloalkyl.

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

By applying the composition for forming a photo-alignment film on a substrate, a photo-alignment inducing layer can be formed on the substrate. The solvent contained in the composition may be the same solvent as the solvent that can be used for forming a polarizing film and is exemplified above, and may be appropriately selected depending on 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 photo alignment layer may be appropriately adjusted according to the kind of the polymer or monomer and the thickness of the target photo alignment layer, and is preferably at least 0.2 mass%, and more preferably in the range of 0.3 to 10 mass% with respect to the mass of the composition for forming a photo alignment layer. The composition for forming a photo-alignment film may contain a polymer material such as polyvinyl alcohol or polyimide, and a photosensitizer within a range that does not significantly impair the characteristics 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 that of applying the alignment composition to a substrate can be exemplified. Examples of the method for removing the solvent from the coated composition for forming the photo-alignment film include a natural drying method, a forced air drying method, a heat drying method, and a reduced pressure drying method.

The irradiation with polarized light may be performed by directly irradiating polarized UV light to a product obtained by removing a solvent from the composition for forming a photo-alignment film applied to the substrate, or 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 polarized light to be irradiated may be a wavelength in a wavelength region where the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet) light having a wavelength 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, and ultraviolet laser such as KrF and ArF, 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 ultrahigh-pressure mercury lamp, and a metal halide lamp are preferable because the emission intensity of ultraviolet rays having a wavelength of 313nm is large. Polarized UV light can be irradiated by irradiating light from the light source through an appropriate polarizer. As the polarizer, a polarizing filter, a polarizing prism of glan-thompson, glan-taylor, or the like, a wire grid type polarizer may be used.

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

The groove (groove) alignment film is a film having a concave-convex pattern or a plurality of grooves (grooves) 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 a trench alignment film, the following methods can be mentioned: a method of forming a concave-convex pattern by exposing the surface of a photosensitive polyimide film through an exposure mask having a slit with a pattern shape, and then performing development and rinsing; a method of forming a layer of a UV curable resin before curing on a plate-like original plate having a groove on the surface, transferring the formed resin layer to a substrate, and then curing it; a method of pressing a roll-shaped original plate having a plurality of grooves against a film of a UV-curable resin before curing, which is formed on a base material, to form irregularities, and then curing the irregularities; and so on.

The thickness of the alignment film (alignment film or photo-alignment film containing 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, and 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 a polarizing film through an adhesive composition. The adhesive composition is not particularly limited, and a known adhesive can be used. In the polarizing plate of the present invention, a transparent protective film is preferably laminated on only one surface of the polarizing film.

< transparent protective film >

The transparent protective film is a substrate having transparency that allows light, particularly visible light, to pass through, and the transparency is a characteristic that the transmittance with respect to light having a wavelength of 380 to 780nm is 80% or more. Specific examples of the transparent protective film include polyolefins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene polymers; polyvinyl alcohol; polyethylene terephthalate; polymethacrylates; a polyacrylate; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; a polycarbonate; polysulfones; polyether sulfone; a polyether ketone; polyphenylene sulfide, polyphenylene ether, and the like. From the viewpoint 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 the 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 commercially available cellulose ester substrates include "Fujitac Film" (Fujifilm Corporation); "KC 8UX 2M", "KC 8 UY", and "KC 4 UY" (Konica Minolta Opto Products Co., Ltd.), etc. Among them, from the viewpoint of the equilibrium water content, a cycloolefin resin, polyethylene terephthalate, and polycarbonate are preferable, and a cycloolefin resin is more preferable.

The required properties of the transparent protective film vary depending on the constitution of the polarizing plate, and a film having as small a retardation as possible is generally preferred. Examples of the film having the smallest retardation property include cellulose ester films having no retardation, such as ZeroTAC (Konica Minolta acta corporation) and Z-tac (fujifilm corporation). Further, 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 hard coating treatment, antireflection treatment, antistatic treatment, or the like.

When the thickness of the transparent protective film is too thin, the strength tends to be lowered and the processability tends to be poor, and therefore, the thickness is usually 10 to 80 μm, preferably 20 to 60 μm, and more preferably 20 to 40 μm.

< retardation 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 an in-plane retardation value at a wavelength of 550nm ].

When the retardation film has the in-plane retardation value shown in the above (1), it functions as a so-called λ/4 plate. The above formula (1) is preferably 100 nm. ltoreq. Re (550). ltoreq.180 nm, and 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 in-plane retardation 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, more 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 (hereinafter, also referred to as "polymerizable liquid crystal compound B") for forming the retardation film is a liquid crystal compound having a polymerizable group, particularly a photopolymerizable group. The photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical, an acid, or the like generated from a photopolymerization initiator. Examples of the photopolymerizable group include vinyl, vinyloxy, 1-chloroethenyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, epoxyethyl, and oxetanyl groups. Among them, preferred are acryloyloxy, methacryloyloxy, vinyloxy, epoxyethyl and oxetanyl, more preferred are acryloyloxy and methacryloyloxy, and still more preferred is acryloyloxy. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and the phase-ordered structure may be a nematic liquid crystal or a smectic liquid crystal. The polymerizable liquid crystal compound B may be used alone or in combination of two or more.

From the viewpoint of ease of film formation and imparting the properties represented by the formula (Y), the polymerizable liquid crystal compound B may be a compound satisfying all of the following (I) to (IV).

(I) Is a compound having thermotropic liquid crystallinity;

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

(III) has pi electrons in a direction [ crossing direction (b) ] crossing the longitudinal direction (a).

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

D(πa)＝N(πa)/N(Aa) (i)

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

D(πb)＝N(πb)/N(Ab) (ii)

the D (π a) and the D (π b) are in a relationship of 0 ≦ D (π a)/D (π b) ≦ 1 [ i.e., a π electron density in the cross direction (b) is greater than a π electron density in the long axis direction (a) ].

The polymerizable liquid crystal compound B satisfying all of the above (I) to (IV) is applied to the alignment film formed by rubbing treatment, and heated to the phase transition temperature or higher, thereby forming a nematic phase. The nematic phase formed by aligning the polymerizable liquid crystal compound B is generally aligned so that the long axis directions of the polymerizable liquid crystal compound are parallel to each other, and the long axis direction is the alignment direction of the nematic phase.

The polymerizable liquid crystal compound B having the above characteristics generally exhibits reverse 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 compounds represented by the above formula (II) may be used alone 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 as used herein means a group having a planar cyclic structure and having a number of pi electrons of [4n +2] according to the houcker rule. Here, n represents an integer. When a ring structure is formed by including a heteroatom such as-N ═ S-, it includes a case where the ring structure satisfies the houcker rule including a non-covalent electron pair on the heteroatom and has aromaticity. The divalent aromatic group preferably contains at least 1 or more of a nitrogen atom, an oxygen atom, and a sulfur atom.

G¹And G²Each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and the carbon atom 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.

T¹And T²Each independently is a single bond or a divalent linking group.

h. i independently represent an integer of 0 to 3, and satisfy a relationship of 1. ltoreq. h + i. Here, when 2. ltoreq. h + i, T¹And T²、G¹And G²Each may be the same as or different from each other.

E¹And E²Each independently represents an alkanediyl group having 1 to 17 carbon atoms in which a hydrogen atom contained in the alkanediyl group may be substituted by a halogen atom and-CH contained in the alkanediyl group₂-may be replaced by-O-, -S-, -Si-, -COO-. P¹And P²Independently represent a polymerizable group or a hydrogen atom, and at least one is a polymerizable group.

G¹And G²Each independently preferably being a1, 4-phenylene group (phenylenediyl group) 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, or a 1-phenylene group 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 atomsThe substituted 1, 4-cyclohexanediyl group is more preferably a1, 4-phenylene group substituted with a methyl group, an unsubstituted 1, 4-phenylene group, or an unsubstituted 1, 4-trans-cyclohexanediyl group, and particularly preferably an unsubstituted 1, 4-phenylene group or an unsubstituted 1, 4-trans-cyclohexanediyl group. In addition, it is preferable that a plurality of G's are present¹And G²At least 1 of them is a divalent alicyclic hydrocarbon group, and is more preferably bonded to L¹Or L²Bonded G¹And G²At least 1 of them is a divalent alicyclic hydrocarbon group.

L¹And L²Each independently is preferably-R^a1COOR^a2-(R^a1And R^a2Each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms), and more preferably-COOR^a2-1-(R^a2-1Represents a single bond, -CH₂-、-CH₂CH₂Any of-COO-and-COOCH) is more preferable₂CH₂-。

T¹And T²Independently of each other, preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R-^a9OR^a10-、-R^a11COOR^a12-、-R^a13OCOR^a14-, or R^a15OC＝OOR^a16-. Here, R^a9～R^a16Each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms. T is¹And T²Each independently more preferably a single bond, -OR^a10-1-、-CH₂-、-CH₂CH₂-、-COOR^a12 ^-1-, or OCOR^a14-1-. Here, R^a10-1、R^a12-1、R^a14-1Each independently represents a single bond, -CH₂-、-CH₂CH₂-any of the above. T is¹And T²Further preferably a single bond, -O-, -CH₂CH₂-、-COO-、-COOCH₂CH₂-, -OCO-, or OCOCH₂CH₂-。

From the viewpoint of exhibiting reverse wavelength dispersibility, h and i are preferably in the range of 2 ≦ h + i ≦ 6, preferably h + i ═ 4, more preferably h ═ 2 and i ═ 2. When h is 2 and i is 2, a symmetrical structure is obtained, and therefore, it is more preferable.

E¹And E²Each independently is preferably an alkanediyl group having 1 to 17 carbon atoms, more preferably an alkanediyl group having 4 to 12 carbon atoms.

As P¹Or P²Examples of the polymerizable group include an epoxy group, a vinyl group, a vinyloxy group, a 1-chloroethenyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an epoxyethyl group, and an oxetanyl group. Among these, acryloyloxy, methacryloyloxy, vinyloxy, epoxyethyl and oxetanyl groups are preferable, and acryloyloxy group is more preferable.

Ar preferably has at least 1 selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring, and a benzene ring and a naphthalene ring are preferable. Examples of the aromatic heterocyclic ring include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a 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 Ar contains a nitrogen atom, the nitrogen atom preferably has pi electrons.

In the formula (II), the total number N of pi electrons contained in the divalent aromatic group represented by Ar_πPreferably 8 or more, more preferably 10 or more, further preferably 14 or more, and particularly preferably 16 or more. Further, it is preferably 30 or less, more preferably 26 or less, and further preferably 24 or less.

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

[ chemical formula 17]

In the formulae (Ar-1) to (Ar-23), symbol represents a connecting part, Z⁰、Z¹And Z²Each 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-alkylsulfamoyl group having 1 to 12 carbon atoms or an N, N-dialkylsulfamoyl group having 2 to 12 carbon atoms.

Q¹And Q²Each independently represents-CR^2’R^3’-、-S-、-NH-、-NR^2’-, -CO-or O-, R^2’And R^3’Each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

J¹And J²Each independently represents a carbon atom or a nitrogen atom.

Y¹、Y²And Y³Each independently represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group.

W¹And W²Each 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 Y¹、Y²And Y³The aromatic hydrocarbon group in (1) includes aromatic hydrocarbon groups having 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group, preferably a phenyl group and a naphthyl group, and more preferably a phenyl group. Examples of the aromatic heterocyclic group include an aromatic heterocyclic group having 4 to 20 carbon atoms and containing at least 1 hetero atom such as a nitrogen atom, an oxygen atom, a sulfur atom and the like, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridyl group, a thiazolyl group, a benzothiazolyl group and the like, and a furyl group, a thienyl group, a pyridyl group, a thiazolyl group and a benzothiazolyl group are preferable.

Y¹And Y²Each independently may be a polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group which may be substituted. Multiple ringThe aromatic hydrocarbon group means a condensed polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group means a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

Z⁰、Z¹And Z²Each independently preferably represents 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, Z⁰More preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, Z¹And Z²More preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group or a cyano group.

Q¹And Q²preferably-NH-, -S-, -NR^2’-、-O-，R^2’Preferably a hydrogen atom. Among them, particularly preferred are-S-, -O-, -NH-.

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

In formulae (Ar-17) to (Ar-23), Y¹Nitrogen atom and Z which may be bonded thereto⁰Together form an aromatic heterocyclic group. Examples of the aromatic heterocyclic group include the aromatic heterocyclic groups described above as the aromatic heterocyclic group that Ar may have, and examples thereof include a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pyrrolidine ring. The aromatic heterocyclic group may have a substituent. In addition, Y¹Nitrogen atom and Z which may be bonded thereto⁰Together form the above-mentioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. Examples thereof include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring. The compound represented by the formula (II) can be produced, for example, by the method described in jp 2010-31223 a.

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, based on 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 component herein means the total amount of components remaining after removing volatile components such as a solvent from the polymerizable liquid crystal composition (B).

The polymerizable liquid crystal composition (B) may contain a polymerization initiator for initiating a polymerization reaction of the polymerizable liquid crystal compound B. Examples of the polymerization initiator include the same polymerization initiators as those exemplified above as the polymerization initiator usable in the polymerizable liquid crystal composition (a). The polymerizable liquid crystal composition (B) may contain, if necessary, a photosensitizing agent, a leveling agent, and additives exemplified as additives contained in the polymerizable liquid crystal composition (a). 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, additives, and the like, followed by mixing and stirring (hereinafter, also referred to as "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 the alignment film that can be used for producing the retardation film include the same substrates and/or alignment films as those exemplified above as the substrates and/or alignment films that can be used for producing the above polarizing film.

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

The thickness of the retardation film is suitably selected depending on the display device to be used, and is preferably 0.1 to 10 μm, more preferably 1 to 5 μm, and still more preferably 1 to 3 μm from the viewpoint of thinning and flexibility.

< circular polarizing plate >

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

The circularly polarizing plate of the present invention may further include other layers (a protective layer, an adhesive layer, and the like) 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 to each other via an adhesive layer or an adhesive layer, or the retardation film may be directly formed on the polarizing film of the present invention by directly applying the composition for forming a retardation film to the polarizing film.

In the circularly polarizing plate of the present invention, the angle formed by 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 still more preferably 25 to 100 μm from the viewpoint of flexibility and visibility of the display device.

< display device >

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

The display device of the present invention can be obtained by, for example, laminating the polarizing film or the polarizing plate of the present invention to the surface of the display device via an adhesive layer. In the case where both surfaces of the circularly polarizing plate have the hydrophobic base material, the effect of the circularly polarizing plate of the present invention can be further exhibited. The term "hydrophobic base material" means, for example, a material having a moisture permeability of 10g/m²D (40 ℃ 90% RH) (JISK 7129) or less.

The kind 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 transmission type liquid crystal display device, a semi-transmission type liquid crystal display device, a reflection type liquid crystal display device, a direct-view type liquid crystal display device, a projection type 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

The present invention will be described in more detail below 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]

< preparation of polarizing plate >

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

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

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

An aqueous adhesive was injected between the obtained polarizer and a cycloolefin film (ZF 14 manufactured by Zeon corporation, japan), and they were bonded to each other by a nip roller. The obtained laminate was dried at 60 ℃ for 2 minutes while maintaining the tension of 430N/m, to obtain a polarizing plate I having a cycloolefin film as a transparent protective film on one surface. The water-based adhesive was prepared by adding 3 parts of carboxyl-modified polyvinyl alcohol (KURARARAY POVAL KL 318; manufactured by KURARARARAY Co., Ltd.) and 1.5 parts of water-soluble polyamide epoxy Resin (Sumirez Resin 650; an aqueous solution having a solid content concentration of 30% manufactured by Sumika Chemtex Co., Ltd.) to 100 parts of water.

< equilibrium moisture content of polarizing plate at 23 ℃ and 50 >

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

< production 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 resulting mixture was stirred at 80 ℃ for 1 hour to obtain a composition for forming a photo-alignment film.

[ chemical formula 18]

[ preparation of polymerizable liquid Crystal composition ]

A polymerizable liquid crystal composition (B1) comprising a polymerizable liquid crystal compound B1 and a polymerizable liquid crystal compound A1 was obtained by mixing (86.0 parts) polymerizable liquid crystal compound B1 having the following structure (14.0 parts), a polymerizable liquid crystal compound A1(14.0 parts), a polyacrylate compound (leveling agent) (BYK-361N; BYK-Chemie Co., Ltd.) (0.12 part), and a photopolymerization initiator, 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) -1-butanone (Irgacure 369; Ciba Specialty Chemicals Co., Ltd.) (3.0 parts).

Polymerizable liquid crystal compound B1:

[ chemical formula 19]

Polymerizable liquid crystal compound a 1:

[ chemical formula 20]

[ method for producing retardation film ]

A cycloolefin polymer film (COP; ZF-14; manufactured by Nippon Zeon Co., Ltd.) was treated 1 time with a corona treatment apparatus (AGF-B10; manufactured by Chunshi electric Co., Ltd.) under conditions of an output of 0.3kW and a treatment speed of 3 m/min. The photo-alignment film-forming composition was applied to a corona-treated surface by a bar coater, dried at 80 ℃ for 1 minute, and irradiated at 100mJ/cm using a polarized UV light irradiation apparatus (SPOT CURE SP-7 with polarizer unit; manufactured by Ushio Motor Co., Ltd.)²The accumulated light amount of (2) is subjected to exposure to polarized UV light to form an alignment film. The thickness of the obtained alignment film was measured by an ellipsometer M-220 (manufactured by Nippon spectral Co., Ltd.) to obtain a thickness of 100 nm.

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 speed of 50 mm/sec, and dried at 120 ℃ for 1 minute. Then, ultraviolet light (cumulative light amount at wavelength 313nm under nitrogen atmosphere: 50) was irradiated from the surface side coated with the polymerizable liquid crystal composition B1 using a high-pressure mercury lamp (Unicure VB-15201 BY-A; manufactured BY Ushio Motor Co., Ltd.)0mJ/cm²) Thereby, a laminate of the retardation film a and the cycloolefin polymer film was formed. The thickness of the resulting retardation film A was measured by a laser microscope (LEXT; manufactured by Olympus corporation), and found to be 2.3. mu.m.

< preparation of circularly polarizing plate >

The polyvinyl alcohol side of the polarizing plate I prepared in the above manner, the retardation film a side of the laminate of the retardation film a and the cycloolefin polymer film were laminated using an acrylic pressure-sensitive adhesive (colorless and transparent, non-oriented) so that the angle (θ) formed 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 retardation film was peeled off to prepare a circular polarizing plate.

< durability test >

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

Evaluation of durability

O: the difference is less than 1 nm.

And (delta): the difference is more than 1nm and less than 10 nm.

X: the difference is more than 10 nm.

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

[ example 2]

< preparation of polarizing plate >

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

(production of composition for Forming alignment layer)

The polymer 2 parts and o-xylene 98 parts described below were mixed, and the resulting mixture was stirred at 80 ℃ for 1 hour to obtain an alignment layer forming composition as a composition for forming a photo alignment layer.

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

[ chemical formula 21]

(preparation of composition for Forming polarizing layer)

The following components were mixed and stirred at 80 ℃ for 1 hour to obtain a composition for forming a polarizing layer.

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

[ chemical formula 22]

25 parts of a polymerizable liquid Crystal Compound represented by the formula (1-7)

[ chemical formula 23]

2.8 parts of a dichroic pigment (1) shown below

[ chemical formula 24]

2.8 parts of a dichroic pigment (2) shown below

[ chemical formula 25]

2.8 parts of a dichroic 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)

Leveling agent 1.2 parts as shown below

Polyacrylate Compound (BYK-361N; manufactured by BYK-Chemie Co., Ltd.)

250 parts of a solvent shown below

Cyclopentanone

(production of polarizing plate)

The surface of a cellulose triacetate film (TAC; KC2 UA; manufactured by Konica Minolta Co., Ltd.) as a base material (transparent protective film) layer was subjected to corona treatment (AGF-B10, manufactured by Chunshi 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 (SPOT CURE SP-7; manufactured by Ushio Motor Co., Ltd.)²The accumulated light amount (313nm basis) was irradiated onto the alignment layer coating layer to form an alignment layer. The polarizing layer-forming composition was applied to 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 under nitrogen atmosphere, cumulative light amount at wavelength of 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 are aligned was obtained.

A circular polarizing plate was produced in the same manner as in example 1 except that this polarizing plate was used, and evaluation was performed. The results are shown in Table 1.

[ example 3]

A polarizing plate and a circular polarizing plate were produced in the same manner as in example 2 except that a cycloolefin polymer film (COP; ZF-14; manufactured by Nippon Zeon Co., Ltd.) was used as the base material (transparent protective film) layer instead of the cellulose triacetate film, and evaluation was performed. 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 patent application laid-open No. 2016-81035 was used instead of the polymerizable liquid crystal compound B1 for the retardation film. The results are shown in Table 1.

Polymerizable compound B2

[ chemical formula 27]

[ example 5]

A polarizing plate and a circularly polarizing plate were produced in the same manner as in example 2 except that the following polymerizable compound B3 was used in place of the polymerizable liquid crystal compound B1 as the retardation film, and evaluation was performed. 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 in the same manner as in example 1 except that cellulose triacetate films (TAC; KC2 UA; manufactured by Konica Minolta Co., Ltd.) were used as transparent protective films on both sides of the polarizer as polarizing plates, and evaluations were carried out. The results are shown in Table 1.

Comparative example 2

A polarizing plate and a circular polarizing plate were produced in the same manner as in example 1 except that a cellulose triacetate film (TAC; KC2 UA; manufactured by Konica Minolta Co., Ltd.) was used as a protective film of the polarizing plate, a cycloolefin polymer film (COP; ZF-14; manufactured by Nippon Zeon Co., Ltd.) was used as a film of the cycloolefin polymer, and a retardation layer was laminated on the cellulose triacetate film side of the polarizing plate, and evaluation was performed. The results are shown in Table 1.

Comparative example 3

A polarizing plate and a circularly polarizing plate were produced 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, and evaluation was performed. The results are shown in Table 1.

Comparative example 4

A polarizing plate and a circularly polarizing plate were produced 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, and evaluation was performed.

[ 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 Zeon corporation, Japan) was used as the retardation film. The results are shown in Table 1.

[ Table 1]

From the results shown in table 1, it is understood that the equilibrium water content of the polarizing plates at 23 ℃ and 50% (relative humidity) is 1.5% or less in examples 1 to 5, and the durability in this case is "o" and "Δ", whereas the durability in comparative examples 1 to 4 in which the equilibrium water content exceeds 1.5% is "x", and the difference is significant. In reference example 1, when the retardation film was formed of a stretched film (retardation film containing no polymerizable liquid crystal compound), the durability was good even when the equilibrium water content of the polarizing plate exceeded 1.5%. It is considered that the retardation film is not affected by moisture in the polarizing plate.

Claims

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

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 a molecular structure,

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

3. The circularly polarizing plate according to claim 1 or 2, wherein the transparent protective film is a cycloolefin resin.

4. The circularly polarizing plate of any one of claims 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 of any one of claims 1 to 4, wherein the polarizing film shows a Bragg peak in X-ray diffraction measurement.

6. The circularly polarizing plate according to claim 4, wherein a 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 of any one of claims 1 to 6, wherein the retardation film satisfies the following formula (1),

100≤Re(550)≤180 (1)

in the formula (1), Re (550) represents an in-plane retardation value at a wavelength of 550 nm.

8. The circularly polarizing plate of any one of claims 1 to 7, 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 retardation values at wavelengths of 450nm and 550nm, respectively.

9. The circularly polarizing plate of any one of claims 1 to 8, wherein an angle formed by a slow axis of the phase difference film and an absorption axis of the polarizing film is substantially 45 °.

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

11. The circularly polarizing plate according to any one of claims 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), the compound is shown in the specification,

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

G¹and G²Each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group;

L¹and L²Each independently is a divalent linking group having an ester structure;

T¹and T²Each independently is a single bond or a divalent linking group;

h and i independently represent an integer of 0-3, and satisfy the relation of h + i not less than 1; here, when 2. ltoreq. h + i, T¹And T²、G¹And G²Each may be the same as or different from each other;

E¹and E²Each independently represents an alkanediyl group having 1 to 17 carbon atoms, wherein a hydrogen atom contained in the alkanediyl group may be replaced by a halogen atomSubstituted, -CH contained in alkanediyl₂-may be replaced by-O-, -S-, -COO-, and in the case of having a plurality of-O-, -S-, -COO-, they do not adjoin each other;

P¹and P²Independently represent a polymerizable group or a hydrogen atom, and at least one is a polymerizable group.

12. The circularly polarizing plate of any one of claims 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 according to any one of claims 1 to 12.