TWI804484B - Composite polarizing plate and liquid crystal display device - Google Patents

Abstract

An objective of the present invention is to provide a composite polarizing plate having improved polarization performance.

The composite polarizing plate of the present invention has an absorption type polarizing film, an alignment film for aligning the absorption type polarizing film, and a reflective polarizing plate, the angle formed by the reflection axis of the reflection type polarizing plate and the absorption axis of the absorption type polarizing film is 8° or less. In addition, a roll shape composite polarizing plate, wherein, the reflection axis of the reflection type polarizing plate is 90° ± 8° in the in-plane direction with respect to the roll transport direction, the absorption axis of the absorption type polarizing film is 90° ± 8° in the in-plane direction with respect to the roll transport direction, the angle formed by the reflection axis of the reflection type polarizing plate and the absorption axis of the absorption type polarizing film is 8° or less.

Description

Composite polarizing plate and liquid crystal display device

The present invention relates to a composite polarizing plate and a liquid crystal display device using it.

In a flat panel display (FPD: Flat Panel Display), an optical film having a polarizing plate, a retardation plate, or the like is used. This polarizing plate is widely used: a polarizing plate made of iodine and other dichroic pigments aligned and adsorbed on a polyvinyl alcohol-based resin film, and an iodine PVA polarizing plate composed of a protective film. In addition, Patent Document 1 discloses a reflective polarizing plate with a multilayer structure obtained by extrusion and stretching and having polymer materials with different in-plane birefringence.

It is known that by disposing the reflective polarizer between the panel and the backlight of the liquid crystal display (LCD: Liquid Crystal Display), the utilization efficiency of light can be improved and black display can be performed.

However, this reflective polarizer does not have sufficient polarizing performance, and cannot achieve a clear black display of LCD when used alone. Therefore, as shown in Patent Document 2, it is disclosed that the transmission axis of this reflective polarizer is aligned with the transmission axis of the iodine PVA polarizer arranged on the inner surface of the LCD panel, and used in combination with the aforementioned iodine PVA polarizer. the content.

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 9-506985

[Patent Document 2] Japanese Patent Application Laid-Open No. 11-160699

However, the iodine PVA polarizing plate is not only thick, but also needs to have an adhesive layer for lamination with the reflective polarizing plate. There are still problems in thickness, and the polarizing performance is also insufficient.

The present invention provides a composite polarizing plate with improved polarizing performance by combining an absorbing polarizing plate and a reflective polarizing plate that can be thinned in thickness.

The present invention includes the inventions of the following [1] to [12].

[1] A composite polarizing plate comprising an absorbing polarizing film, an alignment film for aligning the absorbing polarizing film, and a reflective polarizing plate. The absorbing polarizing film and the reflecting polarizing plate are respectively adjacent to the alignment film, and the reflective polarizing plate The angle formed by the reflection axis and the absorption axis of the absorbing polarizing film is 8° or less.

[2] The composite polarizing plate according to [1], wherein the absorbing polarizing film is a polymer of a polymerizable liquid crystal compound, contains a dichroic dye, and has a thickness of 5 μm or less.

[3] The composite polarizing plate according to [1] or [2], wherein the alignment film is a photo-alignment film that generates an alignment restriction force by light.

[4] The composite polarizing plate according to any one of [1] to [3], wherein the polymerizable liquid crystal compound is a thermotropic (thermotropic, sometimes called thermotropic) liquid crystal compound.

[5] The composite polarizing plate according to any one of [1] to [4], wherein the ratio of the dichroic dye in the polymer of the polymerizable liquid crystal compound is 20 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound servings or less.

[6] The composite polarizing plate according to any one of [1] to [5], wherein the absorbing polarizing film is polymerizable and is aligned and fixed in the in-plane horizontal direction in the state of a smectic liquid crystal phase. Polymers of liquid crystal compounds.

[7] The composite polarizing plate according to any one of [1] to [6], wherein the absorbing polarizing film is a polarizing film having a Bragg peak in X-ray diffraction measurement.

[8] The composite polarizing plate according to any one of [1] to [7], wherein the reflective polarizing plate is a multilayered body of at least two polymer materials having different refractive indices.

[9] The composite polarizing plate according to any one of [1] to [8], which is rectangular and has a transmission axis in the longitudinal direction.

[10] A roll-shaped composite polarizing plate, wherein the reflection axis of the reflective polarizing plate is 90°±8° in the plane direction relative to the transport direction of the roll, and the absorption axis of the absorbing polarizing film is 90° in the plane direction relative to the transport direction of the roll °±8°, and the angle formed by the reflection axis of the reflective polarizer and the absorption axis of the absorbing polarizer is less than 8°.

[11] A method for manufacturing a roll-shaped composite polarizing plate, comprising the following steps 1 to 7: Step 1. Rolling out a roll-shaped reflective polarizing plate on one side, and mixing polymers and solvents containing alignment-limiting forces generated by light The composition is continuously coated on the surface of the aforementioned roll-shaped reflective polarizer to form a first coating film; step 2. heating and drying the aforementioned first coating film to form a first dry film; step 3. The step of forming an alignment film by irradiating polarized ultraviolet rays on the aforementioned first dry film; Step 4. Coating a composition containing a dichroic pigment, a polymerizable liquid crystal compound, a polymerization initiator, and a solvent on the aforementioned alignment film to form The step of the second coating film; step 5. heating and drying the second coating film to form a second drying film; step 6. irradiating ultraviolet rays on the second drying film to polymerize the polymerizable liquid crystal compound to form an absorbing a step of forming a composite polarizing plate by forming a polarizing film; and step 7. a step of winding the aforementioned composite polarizing plate onto a roll.

[12] A liquid crystal display device, in which the composite polarizing plate as described in any one of [1] to [9] is disposed between the backlight unit and the liquid crystal unit, and a reflective polarizing plate surface is disposed on the side of the backlight unit. The side of the liquid crystal cell is equipped with an absorbing polarizing film surface.

According to the present invention, a thin composite polarizing plate and a liquid crystal display device using the polarizing plate can be provided.

The composite polarizing plate of the present invention has an absorbing polarizing film, an alignment film for aligning the absorbing polarizing film, and a reflective polarizing plate. The angle formed by the reflection axis of the reflective polarizing plate and the absorption axis of the absorbing polarizing film is 8 Composite polarizer below °.

The present invention will be described below.

[Absorptive Polarizing Film]

First, the absorbing polarizing film of the present invention will be described. The absorbing polarizing film of the present invention may contain dichroic pigments. It will not specifically limit as long as it contains a dichroic dye.

[Dichroic pigment]

The so-called dichroic pigment refers to a pigment having different properties of absorbance in the long-axis direction and short-axis direction of the molecule. The dichroic pigment preferably has the characteristic of absorbing visible light, especially preferably has a maximum absorption wavelength (λMAX) in the range of 380 to 680 nm.

Such dichroic pigments include, for example, acridine (Acridine) pigments, oxazine (Oxazine) pigments, cyanine (Cyanine) pigments, naphthalene pigments, azo pigments, and anthraquinone (Anthraquinone) pigments, etc. nitrogen pigments. Azo dyes include monoazo dyes, disazo dyes, trisazo dyes, tetrazo dyes, and stilbene azo dyes, and are preferably disazo dyes and trisazo dyes. The dichroic dyes can be used alone or in combination. In order to absorb in the entire range of visible light, it is preferable to combine three or more dichroic dyes, and it is particularly preferable to combine three or more azo dyes.

Examples of azo dyes include compounds represented by formula (I) (hereinafter also sometimes referred to as "compound (I)").

T ¹ -A ¹ (-N=NA ² ) _p -N=NA ³ -T ² (I) [In the formula (I), A ¹ , A ² and A ³ independently represent 1 which may have a substituent , 4-phenylene, naphthalene-1,4-diyl or a divalent heterocyclic group that may have substituents, T ¹ and T ² are electron-attracting groups or electron-releasing groups, and relative to the azo bonding surface It is essentially at the position of 180°. p represents an integer of 0 to 4. When p is 2 or more, each A ² may be mutually the same or different. In the range showing absorption in the visible light region, -N=N- bond can be replaced by -C=C-, -COO-, -NHCO- or -N=CH- bond]

The optional substituents of 1,4-phenylene, naphthalene-1,4-diyl, and divalent heterocyclic groups in ^A1 , ^A2 , and ^A3 include methyl, ethyl, and butyl Alkyl groups with 1 to 4 carbons, such as methoxy, ethoxy, and butoxy, etc., alkoxy groups with 1 to 4 carbons, such as trifluoromethyl, and fluoroalkyl groups with 1 to 4 carbons, such as trifluoromethyl; cyano group; nitro group; halogen atoms such as chlorine atom, fluorine atom, etc.; substituted or unsubstituted amino group such as amino group, diethylamino group and pyrrolidinyl group An amino group of an alkyl group having 1 to 6 carbons, or an amino group in which two substituted alkyl groups are bonded together to form an alkanediyl group having 2 to 8 carbons; an unsubstituted amino group is -NH ₂ ). Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, and a hexyl group. Alkanediyl groups having 2 to 8 carbon atoms include ethylidene, propane-1,3-diyl, butane-1,3-diyl, butane-1,4-diyl, pentane-1 ,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, etc. In order to envelop compound (I) in a high-order liquid crystal structure like smectic liquid crystals, ^A1 , ^A2 and ^A3 are preferably 1,4-phenylene with no substitution or hydrogen substituted by methyl or methoxy group or divalent heterocyclic group, p is preferably 0 or 1. Among them, p is 1 and at least two of the three structures of ^A1 , ^A2 and ^A3 are 1,4-phenylene groups, from the point of view of both the simplicity of molecular synthesis and high polarizing performance Excellent.

2-valent heterocyclic group, can be listed from quinoline (Quinoline), thiazole (Thiozole), benzothiazole, thienothiazole, imidazole (Imidazole), benzimidazole, oxazole (Oxazole) and benzoxazole The base after 2 hydrogen atoms. When ^A2 is a divalent heterocyclic group, it is preferably a structure in which the molecular bonding angle becomes substantially 180°, specifically, benzothiazole, benzimidazole, or benzoxazone in which two 5-membered rings are condensed azole structure.

^T1 and ^T2 are electron-absorbing groups or electron-releasing groups, preferably different structures, more preferably ^T1 is electron-absorbing groups and ^T2 is electron-releasing groups, or ^T1 is electron-releasing groups and T ² is the relationship between electron-attracting groups. Specifically, ^T1 and ^T2 are preferably each independently an alkyl group with 1 to 4 carbons, an alkoxy group with 1 to 4 carbons, a cyano group, a nitro group, and a group with 1 or 2 carbons. An amino group of an alkyl group of 1 to 6, or an amino group of an alkanediyl group having 2 to 8 carbon atoms bonded by two substituted alkyl groups, specifically pyrrolidinyl, piperidinyl, etc., or trifluoromethyl . Among them, in order to envelop compound (I) in a high-order liquid crystal structure like smectic liquid crystals, it must be a structure with a small excluded volume of molecules, so it is preferably an alkyl group with 1 to 4 carbons, and an alkyl group with 1 to 4 carbons. Alkoxy, cyano, amine having 1 or 2 alkyl groups with 1 to 6 carbons, specifically bis(mono)methylamine, di(mono)ethylamine, bis(mono) ) propylamine, di(mono)butylamino, di(mono)pentylamino, di(mono)hexylamino, methylethylamino, methylpropylamino, methylbutyl An amine group, etc., or an amine group in which two substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms.

Examples of such azo dyes include those shown below.

In formula (2-1) to formula (2-6), B ¹ to B ²⁰ independently represent a hydrogen atom, an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, 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 defined above), a chlorine atom or a trifluoromethyl group.

n1 to n4 each independently represent an integer of 0 to 3. In addition, from the viewpoint of obtaining high polarizing performance, B ² , B ⁶ , B ⁹ , B ¹⁴ , B ¹⁸ , and B ¹⁹ are preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom.

When n1 is 2 or more, the plurality of ^B2s may be the same or different, when n2 is 2 or more, the plurality of ^B6s may be the same or different, and when n3 is 2 or more, the plurality of ^B9s may be the same or different , when n4 is 2 or more, the plurality of B ¹⁴ may be the same or different.

The aforementioned anthraquinone dye is preferably a compound represented by formula (2-7).

[In the formula (2-7), R ¹ to R ⁸ independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom.

R ^x represents an alkyl group having 1 to 4 carbons or an aryl group having 6 to 12 carbons]

The aforementioned oxazine dye is preferably a compound represented by formula (2-8).

[In the formula (2-8), R ⁹ to R ¹⁵ independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom.

R ^x represents an alkyl group having 1 to 4 carbons or an aryl group having 6 to 12 carbons]

The aforementioned acridine dye is preferably a compound represented by formula (2-9).

[In the formula (2-9), R ¹⁶ to R ²³ independently represent a hydrogen atom, -R ^x , -NH ₂ , -NHR ^x , -NR ^x ₂ , -SR ^x or a halogen atom.

R ^x represents an alkyl group having 1 to 4 carbons or an aryl group having 6 to 12 carbons]

In formula (2-7), formula (2-8), formula (2-9), the alkyl group with carbon number 1 to 4 represented by R ^x can enumerate methyl, ethyl, propyl, butyl Examples of the aryl group having 6 to 12 carbon atoms include phenyl, tolyl, xylyl, and naphthyl.

The aforementioned cyanine pigment is preferably a compound represented by formula (2-10) or a compound represented by formula (2-11).

[In formula (2-10), D ¹ and D ² independently represent a group represented by any one of formula (2-10a) to formula (2-10d).

n5 represents an integer from 1 to 3]

[In formula (2-11), D ³ and D ⁴ independently represent a group represented by any one of formula (2-11a) to formula (2-11h).

n6 represents an integer from 1 to 3]

When used together with a polymerizable liquid crystal compound described later, the content of the dichroic dye (the total amount when a plurality of species are contained) is generally 100 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound from the viewpoint of obtaining good light absorption characteristics. It is 20 parts by mass or less, preferably 0.1 to 20 parts by mass, especially preferably 1 to 20 parts by mass, more preferably 3 to 15 parts by mass. When the content of the dichroic dye is less than this range, light absorption is insufficient and sufficient polarizing performance cannot be obtained, and when it is more than this range, alignment may be lowered.

[polymerizable liquid crystal]

The absorbing polarizing film of the present invention may contain polymerizable liquid crystals in addition to dichroic dyes. The term "polymerizable liquid crystal" means a compound having a polymerizable group and liquid crystallinity (hereinafter also referred to as a polymerizable liquid crystal compound). The polymerizable group refers to a group participating in a polymerization reaction, preferably a photopolymerizable group. Here, the term "photopolymerizable group" means a group capable of participating in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator described later.

Polymerizable groups include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, oxiranyl, oxygen He Ji and so on. Among them, acryloxy, methacryloxy, ethyleneoxy, oxiranyl and oxo groups are preferred, and acryloxy is particularly preferred. Liquid crystallinity can be thermotropic liquid crystal or lyotropic liquid crystal, and it is preferably thermotropic liquid crystal when mixed with dichroic dye as described later.

When the polymerizable liquid crystal is a thermotropic liquid crystal, it may be a thermotropic liquid crystal compound exhibiting a nematic liquid crystal phase, or a thermotropic liquid crystal compound exhibiting a smectic liquid crystal phase. When the polarizing function of the cured film is developed by polymerization reaction, the liquid crystal state exhibited by the polymerizable liquid crystal compound is preferably a smectic phase, and a high-order smectic phase is particularly preferable from the viewpoint of high performance. Among them, it is particularly preferable to form smectic B phase, smectic D phase, smectic E phase, smectic F phase, smectic G phase, smectic H phase, smectic I phase, smectic J phase, and smectic K phase. Or a high-order smectic liquid crystal compound of a smectic L phase, more preferably a high-order smectic liquid crystal compound forming a smectic B phase, a smectic F phase, or a smectic I phase. When the liquid crystal phase formed by the polymerizable liquid crystal is such a high-order smectic phase, a polarizing film with higher polarizing performance can be produced. In addition, such a polarizing film with high polarizing performance has Bragg peaks derived from the high-order structure of the hexagonal phase or crystal phase in X-ray diffraction measurement.

The Bragg peak is a peak derived from a periodic structure of molecular alignment, and a film with a periodic interval of 3 to 6 Å can be obtained. The polarizing film of the present invention preferably contains a polymer of a polymerizable liquid crystal compound in which the polymerizable liquid crystal is polymerized in a smectic state, from the viewpoint of obtaining higher polarizing properties.

Specific examples of such compounds include compounds represented by the following formula (A) (hereinafter may be referred to as compounds (A)) and the like. These polymerizable liquid crystals can be used alone or in combination of two or more.

U ¹ -V ¹ -W ¹ -X ¹ -Y ¹ -X ² -Y ² -X ³ -W ² -V ² -U ² (A)

[In formula (A), X ¹ , X ² and X ³ independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group, and here, the divalent aromatic group or alicyclic hydrocarbon group represented by the divalent The contained hydrogen atoms may be substituted by halogen atoms, alkyl groups with 1 to 4 carbons, fluoroalkyl groups with 1 to 4 carbons, alkoxy groups with 1 to 4 carbons, cyano groups or nitro groups to form the 2 Carbon atoms in a valent aromatic group or a divalent alicyclic hydrocarbon group may be substituted by an oxygen atom, a sulfur atom, or a nitrogen atom. However, at least one of X ¹ , X ² and X ³ is an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group.

Y ¹ , Y ² , W ¹ and W ² are each independently a single bond or a divalent linking group.

V ¹ and V ² independently represent an optionally substituted alkanediyl group having 1 to 20 carbon atoms, and -CH ₂ - constituting the alkanediyl group may be substituted with -O, -S- or NH-.

^U1 and ^U2 independently represent a polymerizable group or a hydrogen atom, at least one of which is a polymerizable group.

In the compound (A), at least one of X ¹ , X ² and X ³ is an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group. In particular, X ¹ and X ³ are preferably cyclohexane-1,4-diyl which may have substituents, and the cyclohexane-1,4-diyl is more preferably trans-cyclohexane-1,4 - two bases. When a trans-cyclohexane-1,4-diyl structure is contained, smectic liquid crystallinity tends to be easily exhibited. In addition, examples of substituents that the optionally substituted 1,4-phenylene group or the optionally substituted cyclohexane-1,4-diyl group may have include methyl, ethyl, and butyl groups. C1-4 alkyl groups, cyano groups, and halogen atoms such as chlorine atoms and fluorine atoms are preferably unsubstituted.

Y ¹ and Y ² are preferably each independently a single bond, -CH ₂ CH ₂ -, -CH ₂ O-, -COO-, -OCO-, -N=N-, -CR ^a =CR ^b -, -C≡C- or CR ^a =N-, R ^a and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y ¹ and Y ² are especially preferably -CH ₂ CH ₂ -, -COO-, -OCO- or a single bond, when X ¹ , X ² and X ³ do not contain cyclohexane-1,4-diyl, Y ¹ and Y ² are preferably different bonding modes from each other. When Y ¹ and Y ² have different bonding modes, it tends to show smectic liquid crystallinity easily.

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

The alkanediyl groups having 1 to 20 carbon atoms represented by ^V1 and ^V2 include methylene, ethylidene, propane-1,3-diyl, butane-1,3-diyl, butane-1,3-diyl, butane Alkane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, decane Alkane-1,10-diyl, tetradecane-1,14-diyl, eicosane-1,20-diyl, etc. V ¹ and V ² are preferably an alkanediyl group having 2 to 12 carbon atoms, particularly preferably a linear alkanediyl group having 6 to 12 carbon atoms. The alkanediyl group having 6 to 12 carbon atoms constituting a linear chain improves crystallinity and tends to easily exhibit smectic liquid crystallinity.

The optional substituents of the alkanediyl having 1 to 20 carbon atoms that may have substituents include cyano groups, chlorine atoms, halogen atoms such as fluorine atoms, etc., but the alkanediyl groups are preferably unsubstituted , particularly preferably an unsubstituted straight-chain alkanediyl group.

Both U ¹ and U ² are preferably polymerizable groups, and more preferably both are photopolymerizable groups. A polymerizable liquid crystal compound having a photopolymerizable group is more advantageous in that it can be polymerized at a lower temperature than a thermally polymerizable group, and the liquid crystal can be formed into a polymer with a higher degree of order.

The polymeric groups represented by U ¹ and U ² may be different or the same. Polymerizable groups include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloxy, methacryloxy, oxiranyl, oxygen He Ji and so on. Among them, acryloxy, methacryloxy, ethyleneoxy, oxiranyl and oxoyl are preferred, and methacryloxy and acryloxy are particularly preferred.

Examples of such polymerizable liquid crystal compounds include those shown below.

Among the aforementioned compounds exemplified, it is preferably selected from the group consisting of formula (1-2), formula (1-3), formula (1-4), formula (1-6), formula (1-7), formula ( 1-8), formula (1-13), formula (1-14) and formula (1-15) at least one kind of the group consisting of compounds represented.

The illustrated compound (A) can be used alone or in combination for a polarizing film. Moreover, when combining 2 or more types of polymerizable liquid crystals, it is preferable that at least 1 type is a compound (A), and it is more preferable that 2 or more types are compounds (A). By combining two or more types of polymerizable liquid crystals, liquid crystallinity may be temporarily maintained even at temperatures below the liquid crystal-crystal phase transition temperature. The mixing ratio when combining two types of polymerizable liquid crystals is usually 1:99 to 50:50, preferably 5:95 to 50:50, particularly preferably 10:90 to 50:50.

Compound (A) can be produced, for example, by a generally known method described in Lub et al.

The content ratio of the polymerizable liquid crystal in the polarizing film is usually 50 to 99.5 parts by mass, preferably 60 to 99 parts by mass, particularly preferably 70 to 98 parts by mass, and more preferably 100 parts by mass of the solid content of the polarizing film. 80 to 97 parts by mass. When the content ratio of a polymeric liquid crystal exists in the said range, orientation tends to improve. Here, the solid content means the total amount of components after subtracting the solvent from the composition for forming a polarizing film.

[solvent]

The composition for forming an absorbing polarizing film may contain a solvent. Generally speaking, since a polymerizable liquid crystal compound has a high viscosity, it can be easily applied by constituting a composition for forming a polarizing film dissolved in a solvent, and as a result, it is often easy to form a polarizing film. The solvent is preferably one that can completely dissolve the polymerizable liquid crystal compound, and is also preferably a solvent that is inert to the polymerization reaction of the polymerizable liquid crystal compound.

Solvents include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol Ester solvents such as alcohol methyl ether acetate, γ-butyrolactone or propylene glycol methyl ether acetate and ethyl lactate; acetone, ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone and methyl isobutyl Ketone solvents such as ketones; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane ; Chlorinated solvents such as chloroform and chlorobenzene; Dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidine Amide-based solvents such as ketones, etc. These solvents can be used individually or in combination of 2 or more types.

The content of the solvent is preferably 50 to 98% by mass relative to the total amount of the above-mentioned absorbing polarizing film forming composition. In other words, the content of the solid content in the composition for forming an absorbing polarizing film is preferably 2 to 50% by mass. When the content of the solid content is 50% by mass or less, the viscosity of the composition for forming an absorbing polarizing film decreases, so the thickness of the polarizing film becomes substantially uniform, and unevenness tends to be less likely to occur in the polarizing film. In addition, the content of the solid component can be determined in consideration of the thickness of the polarizing film to be manufactured.

[levelling agent]

The composition for forming an absorption type polarizing film may contain a leveling agent. The so-called leveling agent refers to an additive that has the function of adjusting the fluidity of the composition and making the film obtained by coating the composition more flat. Fluoroalkyl-based leveling agent. Specifically, DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all of which are manufactured by Dow Corning Toray Co., Ltd.); KP321, KP323, KP324, KP326, KP340, KP341 can be listed . ; Fluorinert (registered trademark) FC-72, same FC-40, same FC-43, same FC-3283 (the above are all made by 3M Sumitomo Co., Ltd.); Megafac (registered trademark) R-08, same R-30, Same as R-90, same as F-410, same as F-411, same as F-443, same as F-445, same as F-470, same as F-477, same as F-479, same as F-482, same as F-483, Same as F-554, same as F-556 (all above are made by DIC Co., Ltd.); F-Top (product name) EF301, same as EF303, same as EF351, same as EF352 (all above are made by Mitsubishi Materials Electronic Chemicals Co., Ltd.) ;Surflon (registered trademark) S-381, same S-382, same S-383, same S-393, same SC-101, same SC-105, KH-40, SA-100 (the above are all shares of AGC Seimi Chemical Co., Ltd.); product name E1830, the same as E5844 (the above are Daikin Fine Chemical Research Institute Co., Ltd.); BM-1000, BM-1100, BYK-352, BYK-353 and BYK-361N (all are product names ; BM Chemie company) and so on. Among them, polyacrylate-based leveling agents and perfluoroalkyl-based leveling agents are preferred.

When the composition for forming an absorbing polarizing film contains a leveling agent, it is preferably 0.01 to 5 parts by mass, particularly preferably 0.1 to 5 parts by mass, more preferably 0.1 to 3 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal. parts by mass. When the content of the leveling agent is within the above range, it is easy to horizontally align the polymerizable liquid crystal, and the obtained polarizing film tends to become smooth. When the content of the leveling agent relative to the polymerizable liquid crystal exceeds the above-mentioned range, unevenness tends to easily occur in the obtained polarizing film. The composition for forming an absorbing polarizing film may contain two or more types of leveling agents.

[polymerization initiator]

The composition for forming an absorbing polarizing film may contain a polymerization initiator. A polymerization initiator is a compound that can start the polymerization reaction of a polymerizable liquid crystal. The polymerization initiator is preferably a photopolymerization initiator that generates active radicals by the action of light from the viewpoint of not depending on the phase state of the thermotropic liquid crystal.

Polymerization initiators include, for example, benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts, and perzium salts, etc. .

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

Diphenyl ketone compounds, for example, diphenyl ketone, methyl o-benzoyl benzoate, 4-phenyl diphenyl ketone, 4-benzoyl-4'-methyl diphenylsulfide Ether, 3,3',4,4'-tetra(tertiary butylperoxycarbonyl) benzophenone and 2,4,6-trimethylbenzophenone, etc.

Alkylphenone compounds, for example, diethoxyacetophenone, 2-methyl-2-N-morpholinyl-1-(4-methylthiophenyl)propane-1-one, 2- Benzyl-2-dimethylamino-1-(N-morpholinophenyl)butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1, 2-diphenyl-2,2-dimethoxyethan-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propane-1- Ketones, oligomers of 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one, etc.

Acylphosphine oxide compounds, such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide things etc.

Triazine compounds, for example, 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl) Base)-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, etc.

As a polymerization initiator, a commercial item can be used. Commercially available polymerization initiators include Irgacure (registered trademark) 907, 184, 651, 819, 250, and 369, 379, 127, 754, OXE01, OXE02, OXE03 (manufactured by Ciba Specialty Chemicals); Seikuol ( Registered trademarks) BZ, Z, and BEE (manufactured by Seiko Chemical Co., Ltd.); Kayacure (registered trademark) BP100, and UVI-6992 (manufactured by Dow Chemical Co., Ltd.); Adeka Optomer SP-152, N-1717, N- 1919, SP-170, Adeka Arkls NCI-831, Adeka Arkls NCI-930 (ADEKA Co., Ltd.); TAZ-A, and TAZ-PP (Nippon Siebel Hagner Co., Ltd.); and TAZ-104 (Sanwa Chemical limited company), etc. The polymerization initiator in the composition for forming a polarizing film may be 1 type or a mixture of 2 or more types of polymerization initiators in accordance with a light source.

The content of the polymerization initiator in the composition for forming an absorbing polarizing film can be appropriately adjusted according to the type and amount of the polymerizable liquid crystal, and is usually 0.1 to 30 parts by mass relative to 100 parts by mass of the content of the polymerizable liquid crystal , preferably 0.5 to 10 parts by mass, especially preferably 0.5 to 8 parts by mass. When content of a polymerization initiator exists in the said range, it can superpose|polymerize without disturbing the alignment of a polymerizable liquid crystal.

[sensitizer]

The composition for forming an absorbing polarizing film may contain a sensitizer. The sensitizer is preferably a photosensitizer. The sensitizer can include xanthone compounds such as Xanthone and Thioxanthone (such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); Anthracene and alkoxy-containing anthracene (such as dibutoxyanthracene, etc.) and other anthracene compounds; phenothiazine (Phenothiazine) and rubrene (Rubrene), etc.

When the composition for forming an absorbing polarizing film contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal contained in the composition for forming an absorbing polarizing film can be further accelerated. The amount of the sensitizer is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, more preferably 0.5 to 3 parts by mass relative to 100 parts by mass of the content of the polymerizable liquid crystal.

[polymerization inhibitor]

From the viewpoint of stably advancing the polymerization reaction, the composition for forming an absorbing polarizing film may contain a polymerization inhibitor. The progress of the polymerization reaction of the polymerizable liquid crystal can be controlled by the polymerization inhibitor.

The aforementioned polymerization inhibitors include hydroquinone, alkoxy-containing hydroquinone, alkoxy-containing catechol (such as butyl catechol, etc.), gallol (Pyrogallol), 2 , 2,6,6-Tetramethyl-1-piperidinyloxy free radicals and other free radical scavengers; Thiophenols; β-naphthylamines and β-naphthols, etc.

When the composition for forming an absorbing polarizing film contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, relative to 100 parts by mass of the content of the polymerizable liquid crystal, More preferably, it is 0.5 to 3 parts by mass. When the content of the polymerization inhibitor is within the above range, polymerization can be performed without disturbing the alignment of the polymerizable liquid crystal.

"Manufacturing method of absorbing polarizing film"

The absorbing polarizing film of the present invention can be produced by coating a composition for forming an absorbing polarizing film on a substrate and an alignment film.

<Coating of Absorptive Polarizing Film Forming Composition>

The method of coating the composition for forming an absorbing polarizing film on a substrate or an alignment film includes extrusion coating, direct gravure coating, reverse gravure coating, CAP coating, and slit coating. Cloth method, micro gravure method, die coating method, inkjet method, etc. Moreover, the method of coating using the coater, such as a dip coater, a bar coater, and a spin coater, etc. are mentioned. Among them, when coating continuously in a roll-to-roll format, coating methods based on the microgravure method, the inkjet method, the slit coating method, and the die coating method are preferable. When coating on monolithic substrates such as glass, the spin coating method with high uniformity is preferred. In roll-to-roll coating, the composition for forming an absorbing polarizing film may be continuously coated on an alignment film obtained by applying the composition for forming an alignment film to a substrate to form an alignment film.

<Drying of Absorptive Polarizing Film Forming Composition>

The method of removing the solvent contained in the composition for forming an absorbing polarizing film includes, for example, natural drying, ventilation drying, heat drying, reduced-pressure drying, and a combination thereof. Of these, natural drying or heat drying is preferred. The drying temperature is preferably in the range of 0 to 200°C, more preferably in the range of 20 to 150°C, more preferably in the range of 50 to 130°C. The drying time is preferably from 10 seconds to 10 minutes, especially preferably from 30 seconds to 5 minutes. The composition for forming an alignment film and the alignment polymer composition can also be dried in the same manner.

<Polymerization of polymerizable liquid crystal compounds>

The method of polymerizing the polymerizable liquid crystal compound is preferably photopolymerization. Photopolymerization can be carried out by irradiating active energy rays on a substrate or by coating a laminate of an absorbing polarizing film-forming composition containing a polymerizable liquid crystal compound on an alignment film. The active energy ray to be irradiated can be adjusted according to the type of polymerizable liquid crystal compound contained in the dry film (especially the type of photopolymerizable functional group contained in the polymerizable liquid crystal compound), and the photopolymerization when the photopolymerization initiator is contained. The kind of starter, and the amount thereof are appropriately selected. Specifically, one or more kinds of light selected from the group consisting of visible light, ultraviolet rays, infrared rays, X-rays, α-rays, β-rays, and γ-rays can be used. Among them, from the point of view that it is easy to control the progress of the polymerization reaction and can be used in a device widely used as a photopolymerization device in this field, ultraviolet rays are preferable, and photopolymerization by ultraviolet rays is preferable. The type of polymerizable liquid crystal compound is selected in a certain way.

The light sources of the aforementioned active energy rays include, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light source with wavelength range from 380 to 440nm, chemical lamp, black light lamp, microwave excited mercury lamp, metal halide lamp, etc.

The ultraviolet irradiation intensity is usually 10mW/cm ² to 3,000mW/cm ² . The intensity of ultraviolet irradiation is preferably an intensity in a wavelength region effective for activation of a cationic polymerization initiator or a radical polymerization initiator. The time for irradiating light is usually 0.1 second to 10 minutes, preferably 0.1 second to 5 minutes, particularly preferably 0.1 second to 3 minutes, more preferably 0.1 second to 1 minute. When irradiating once or multiple times with such an ultraviolet irradiation intensity, the accumulated light amount is usually 10mJ/cm ² to 3,000mJ/cm ² , preferably 50mJ/cm ² to 2,000mJ/cm ² , especially preferably 100mJ/cm ² to 1,000 mJ/cm ² . When the accumulated light amount is below this range, the curing of the polymerizable liquid crystal compound may be insufficient, and favorable transferability may not be obtained. On the contrary, when the accumulated light amount exceeds this range, the performance of the polarizing film may decrease.

[Substrate]

Examples of the substrate include glass substrates and film substrates, preferably film substrates, and particularly preferably long roll-shaped films from the viewpoint of continuous production. The resin constituting the film substrate includes polyolefins such as polyethylene, polypropylene, and norcamphene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid Esters; polyacrylates; cellulose esters of cellulose triacetate, cellulose diacetate and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; Ether ketone; polyphenylene sulfide and polyphenylene ether.

Examples of commercially available cellulose ester substrates include "Fujitac Film" (manufactured by Fujifilm Co., Ltd.), "KC8UX2M", "KC8UY" and "KC4UY" (above, manufactured by Konica Minolta Opto Co., Ltd.).

Commercially available cyclic olefin-based resins include "Topas" (registered trademark) (manufactured by Ticona (Germany)), "Arton" (registered trademark) (manufactured by JSR Co., Ltd.), "ZEONOR" (registered trademark) , "ZEONEX" (registered trademark) (manufactured by Zeon Japan Co., Ltd. above), and "Apel" (registered trademark) (manufactured by Mitsui Chemicals Co., Ltd.). Such a cyclic olefin-based resin can be formed into a film by a generally known means such as a solvent casting method and a melt extrusion method to form a base material. A commercially available cyclic olefin-based resin substrate can also be used. Commercially available cyclic olefin-based resin substrates include "Essina" (registered trademark), "SCA40" (registered trademark) (manufactured by Sekisui Chemical Industry Co., Ltd.), "Zeonor Film" (registered trademark) ( Optes Co., Ltd.) and "Arton Film" (registered trademark) (JSR Co., Ltd.).

The thickness of the base material is preferably thinner from the point of view of the actual handling level and quality, but if it is too thin, the strength will decrease and the workability will tend to deteriorate. The thickness of the substrate is usually 5 μm to 300 μm, preferably 20 μm to 200 μm. The composite polarizer can be formed by combining the base material with the absorbing polarizing film and the reflective polarizer manufactured in this way. In this case, from the viewpoint of thinning, it is preferable to peel off the substrate and transfer the absorption-type polarizing film to the reflection-type polarizing plate.

As a preferred substrate, a reflective polarizer can also be directly used as a substrate. A composite polarizing plate in which the composition for forming an absorbing polarizing film is directly coated using a base material of a reflective polarizing plate is preferable since the production efficiency is good and a substantial reduction in thickness can be achieved. Film substrates include polyethylene naphthalate (PEN: Polyethylene Naphthalate) and its isomers (such as 2,6-, 1,4-, 1,5-, 2,7- and 2,3 -PEN), polyalkylene terephthalate (such as polyethylene terephthalate, polybutylene terephthalate and poly-1,4-cyclohexanedimethylene terephthalate) , polyimide resin (such as polyacrylimide), polyetherimide, atactic polystyrene, polycarbonate, polymethacrylate (such as polyisobutyl methacrylate, polymethacrylic acid Propyl methacrylate, polyethyl methacrylate and polymethyl methacrylate), polyacrylates (such as polybutyl acrylate and polymethyl acrylate), cellulose derivatives (such as ethyl cellulose, cellulose acetate , cellulose propionate, cellulose acetate butyrate and cellulose nitrate), polyalkylene polymers (such as polyethylene, polypropylene, polybutene, polyisobutylene and poly(4-methyl)pentene ene), fluorinated polymers (such as perfluoroalkoxy resins, polytetrafluoroethylene, fluoroethylene-propylene copolymers, polyvinylidene fluoride and polychlorotrifluoroethylene), chlorinated polymers (such as polyvinylidene chloride Ethylene and polyvinyl chloride), polyether, polyacrylonitrile, polyamide, silicone resin, epoxy resin, polyethylene acetate, polyetheramide, ionomer resin, elastomer ( Plastics such as polybutadiene, polyisoprene and neoprene rubber) and polyurethane.

[Reflective polarizer]

The reflective polarizer used in the present invention is a polarized light conversion element capable of separating natural light into transmitted polarized light and reflected polarized light or scattered polarized light. The reflective polarizer can specifically be an anisotropic multi-layer film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. As a commercial item of this anisotropic multilayer film, for example, a brand name "DBEF" or "APF" (manufactured by 3M Corporation, 3M Sumitomo Co., Ltd.) can be preferably used. The reflective polarizer is not limited to the principle, and it can also be a combination of cholesteric liquid crystal and λ/4 plate.

The thickness of the reflective polarizing plate may be about 10 to 100 μm, and is preferably 10 to 50 μm from the viewpoint of thinning the optical laminate, composite polarizing plate, and liquid crystal display device.

[Alignment film]

In the present invention, the alignment film has an alignment restriction force for aligning the polymerizable liquid crystal in a desired direction.

The alignment film facilitates the liquid crystal alignment of the polymerizable liquid crystal. The states of liquid crystal alignment such as horizontal alignment, vertical alignment, hybrid alignment, and oblique alignment vary according to the properties of the alignment film and the polymerizable liquid crystal, and the combination can be selected arbitrarily. For example, if the alignment film is a material that exhibits the alignment restriction force of horizontal alignment, the polymerizable liquid crystal can form horizontal alignment or mixed alignment; if it is a material that exhibits vertical alignment, the polymerizable liquid crystal can form vertical alignment or oblique alignment. Expressions such as horizontal and vertical indicate the direction of the long axis of the aligned polymerizable liquid crystal based on the plane of the polarizing film. For example, vertical alignment means that the long axis of the polymerizable liquid crystal is aligned in a direction perpendicular to the plane of the polarizing film. The so-called vertical here means 90°±20° relative to the plane of the polarizing film. In the composite polarizing plate, the alignment direction of the absorbing polarizing film is preferably horizontal alignment, and the horizontal alignment film can be preferably applied.

When the alignment film is formed of an alignment polymer, it can be adjusted arbitrarily by the surface state or friction conditions. When it is formed by a photo-alignment polymer, it can be adjusted arbitrarily by polarizing light irradiation conditions, etc. . In addition, liquid crystal alignment can also be controlled by selecting physical properties such as surface tension and liquid crystallinity of the polymerizable liquid crystal.

The alignment film formed between the substrate and the polarizing film is preferably insoluble in the solvent used to form the polarizing film on the alignment film, and has heat resistance for solvent removal or heat treatment for alignment of liquid crystals. Alignment films include alignment films made of alignment polymers, photo-alignment films, and groove alignment films. When applied to long roll-shaped films, the alignment direction can be easily controlled. See, it is preferably a photo-alignment film.

The thickness of the alignment film is usually in the range of 10 nm to 5000 nm, preferably in the range of 10 nm to 1000 nm, especially in the range of 30 nm to 300 nm.

Alignment polymers used in the rubbed alignment film include polyamides or gelatins with amide bonds in the molecule, polyimides with imine bonds in the molecule, and polyamide acids of the hydrolyzed products. , polyvinyl alcohol, alkyl-denatured polyvinyl alcohol, polyacrylamide, polyoxazole (Polyoxazole), polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid and polyacrylates, etc. Among them, polyvinyl alcohol is preferable. These alignment polymers can be used individually or in combination of 2 or more types.

An alignment film made of an alignment polymer is usually made by dissolving an alignment polymer in a solvent (hereinafter also referred to as "alignment polymer composition") coated on a substrate and removing the solvent, Or it can be obtained by coating the alignment polymer composition on the substrate, removing the solvent, and then rubbing (rubbing method).

The aforementioned solvents include alcohol solvents such as water, methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol, etc. Ester solvents such as alcohol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate and ethyl lactate; acetone, ethyl ketone, cyclopentanone, cyclohexanone, methyl pentanone and methyl isobutyl Ketone solvents such as ketones; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane ; Hydrocarbon solvents substituted by chlorine such as chloroform and chlorobenzene, etc. These solvents can be used individually or in combination of 2 or more types.

The concentration of the alignment polymer in the alignment polymer composition may be within a range in which the alignment polymer can be completely dissolved in the solvent, and is preferably 0.1 to 20% by mass in terms of solid content relative to the solution, especially Preferably, it is 0.1 to 10% by mass.

For the alignment polymer composition, commercially available alignment film materials can be directly used. Examples of commercially available alignment film materials include Sunever (registered trademark) (manufactured by Nissan Chemical Industries, Ltd.), Optomer (registered trademark) (manufactured by JSR Corporation), and the like.

The method of coating the alignment polymer composition on the substrate includes coating methods such as spin coating method, extrusion method, gravure coating method, die coating method, rod coating method, and spraying method. , or a generally known method such as a printing method such as a flexographic printing method. When the polarizing film of the present invention is coated by a roll-to-roll continuous production method, printing methods such as a gravure coating method, a die coating method, or a flexographic printing method are generally used as the coating method.

By removing the solvent contained in the alignment polymer composition, a dry film of the alignment polymer is formed. The method for removing the solvent includes a natural drying method, a ventilation drying method, a heating drying method, and a reduced-pressure drying method.

The rubbing method includes: making an alignment polymer film formed on the surface of the substrate by applying an alignment polymer composition on the substrate and annealing, contacting a rubbing roller wound with a rubbing cloth and rotating. method.

A photo-alignment film is usually coated on a substrate with a composition comprising a polymer having a photoreactive group or a monomer and a solvent (hereinafter also referred to as "photo-alignment film-forming composition"), and irradiated with polarized light (preferably Obtained for polarized light UV). The photo-alignment film is particularly preferable in that the direction of the alignment-regulating force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light. In the present invention, the orientation is controlled in a direction that is substantially 90° in the in-plane direction with respect to the conveying direction of the elongated roll, whereby the absorption axis of the absorbing polarizing film can be formed substantially in the in-plane direction relative to the conveying direction of the roll 90° absorbing polarizing film. The term "substantially 90°" refers to the range of 90°±8°. Forming a roll-shaped absorbing polarizing film having an absorption axis within a range of 90°±8° in-plane with respect to the roll conveying direction is a preferable form for producing this composite polarizing plate.

The so-called photoreactive group refers to a group that generates liquid crystal alignment energy by light irradiation. Specifically, light irradiation induces molecular alignment or heterogeneous reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction, which becomes the origin of liquid crystal alignment energy. Among the photoreactive groups, those that cause a dimerization reaction or a photocrosslinking reaction are preferable from the viewpoint of excellent alignment properties. The photoreactive groups that can produce the above reactions are preferably those with unsaturated bonds, especially double bonds, especially those selected from carbon-carbon double bonds (C=C bonds), carbon-nitrogen double bonds (C= N bond), nitrogen-nitrogen double bond (N=N bond), and carbon-oxygen double bond (C=O bond).

Photoreactive groups with C=C bonds include vinyl groups, polyalkenyl groups, stilbene groups, stilbazole groups, stilbazolium groups, and chalcone groups. Cinnamoyl and Cinnamoyl etc. Chalcone group and cinnamoyl group are preferable from the point of view of easy control of reactivity and expression of alignment restriction force during photo-alignment.

The photoreactive group having a C=N bond includes an aromatic Schiff base group and a group containing a structure such as an aromatic hydrazone.

The photoreactive group with N=N bond can include azophenyl group, azonaphthyl group, aromatic heterocyclic azo group, bis-azo group and formazan group, etc., or azo Oxybenzene is the basic structure.

The photoreactive group having a C=O bond includes a diphenyl ketone group, a coumarin group, an anthraquinone group, a maleimide group, and the like. These groups may have substituents such as alkyl, alkoxy, aryl, aryloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, and haloalkyl.

The solvent of the photo-alignment film-forming composition is preferably one that can dissolve the polymer and monomer having a photoreactive group. Examples of the solvent include the solvents listed above as the solvent for the alignment polymer composition. .

The content of the polymer or monomer with a photoreactive group relative to the composition for forming a photoalignment film may vary depending on the type of polymer or monomer with a photoreactive group or the thickness of the photoalignment film to be produced To adjust appropriately, it is preferably set at 0.2% by mass or more, and preferably in the range of 0.3 to 10% by mass. In addition, a polymer material such as polyvinyl alcohol or polyimide or a photosensitizer may be contained within the range that does not significantly impair the properties of the photo-alignment film.

The method of applying the composition for forming a photo-alignment film to a substrate includes the same method as the above-mentioned method of applying the alignment polymer composition to a substrate. The method of removing the solvent from the applied composition for forming an optical alignment film includes the same method as the method of removing the solvent from the alignment polymer composition.

When irradiating polarized light, it may be in the form of directly irradiating polarized light on the composition for forming a photoalignment film coated on a substrate or the like after removing the solvent, or by irradiating polarized light from the substrate side and allowing the polarized light to pass through the substrate. form of exposure. In addition, the polarized light is preferably substantially parallel light. The wavelength of the polarized light to be irradiated may be in the wavelength region where the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet rays) having a wavelength of 250 to 400 nm is preferable. The light sources used for the polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, ultraviolet lasers such as KrF, ArF, etc., especially high-pressure mercury lamps, ultra-high pressure mercury lamps, and metal halides. lamp. These lamps are preferable because the luminous intensity of ultraviolet rays with a wavelength of 313 nm is high. Polarized light can be irradiated by irradiating light from the aforementioned light source through an appropriate polarizing element. As the polarizing element, a polarizing filter, a polarizing filter such as Glan-Thompson, Glan-Taylor, or a wire grid type polarizing element can be used.

When rubbing or polarized light irradiation is performed, masking can be performed, or a plurality of regions (patterns) in which the direction of liquid crystal alignment is different can be formed.

The groove (groove) alignment film is a film with a concave-convex pattern or a plurality of grooves (grooves) on the film surface. When liquid crystal molecules are placed on a film having a plurality of linear grooves arranged at equal intervals, the liquid crystal molecules can be aligned along the direction of the grooves.

The method of obtaining a trench alignment film includes: exposing the surface of a photosensitive polyimide film through an exposure mask having pattern-shaped slits, and then developing and showering to form a concave-convex pattern. A method; a method of forming a UV curable resin layer before hardening on a plate-shaped base material having grooves on the surface, and then moving the resin layer to a base material and then hardening; and pressing the roll-shaped base material having a plurality of grooves A method in which unevenness is formed by contacting an uncured UV curable resin film formed on a base material, and then cured. Specifically, the method described in Unexamined-Japanese-Patent No. 6-34976 and Unexamined-Japanese-Patent No. 2011-242743, etc. are mentioned.

In order to obtain alignment with little alignment disorder, the width of the convex portion of the trench alignment film is preferably 0.05 μm to 5 μm, the width of the convex portion is preferably 0.1 μm to 5 μm, and the depth of the unevenness is preferably 2 μm or less. 0.01 μm to less than 1 μm.

The thickness of the polarizing film formed in this way is usually not less than 0.5 μm and not more than 10 μm, preferably not less than 1 μm and not more than 5 μm, more preferably not less than 1 μm and not more than 4 μm. Therefore, the thickness of the coating film for forming the present polarizing film may be determined in consideration of the thickness of the obtained present polarizing film.

The thickness of the polarizing film can be obtained by measuring with an interferometric film thickness meter, a laser microscope, or a stylus film thickness meter.

The composite polarizing plate of the present invention can be obtained as a composite polarizing plate coated with an absorbing polarizing film formed on a reflective polarizing plate as described above, or can be obtained by combining an absorbing polarizing film coated and formed on another substrate with The alignment film is transferred to the reflective polarizer through an adhesive or an adhesive to obtain a composite polarizer. In addition, at this time, it is formed so that the reflection axis of the reflective polarizing plate and the absorption axis of the absorbing polarizing film substantially coincide. The angle formed by the reflection axis of the reflective polarizing plate and the absorption axis of the absorbing polarizing film is preferably 8° or less, particularly preferably 4° or less, and more preferably 2° or less. The angle can be controlled by controlling the alignment control force of the alignment film that aligns the absorbing polarizing film as described above.

In the prior art, composite polarizers are industrially produced from roll-shaped absorbing polarizers and roll-shaped reflective polarizers. The absorption type polarizer uses iodine PVA polarizer, but due to the need for a high degree of longitudinal uniaxial stretching, the absorption axis is parallel to the direction of roller transport. On the other hand, in reflective polarizing plates, transverse stretching is required to increase the width of the film, so the absorption axis is perpendicular to the conveying direction of the roll. That is, in order to laminate the two polarizers, one of the polarizers must first be cut into a single sheet, and then laminated. In this case, it cannot be applied because a seam will be generated in a large LCD-TV application or the like.

However, since the composite polarizing plate of the present invention can arbitrarily control the absorption axis of the absorbing polarizing film, it can be continuously stacked in the form of a long roll, which greatly improves the production efficiency. In addition, it can also be applied to large LCD-TV applications, etc. In the elongated roll form, the length in the transport direction of the roll is usually 10 to 10000 m, preferably 100 to 10000 m from the viewpoint of productivity.

In the roll-shaped composite polarizing plate, the reflection axis of the reflective polarizing plate is preferably 90°±8° in the in-plane direction, more preferably 90°±4°, with respect to the conveying direction of the roll. In addition, the absorption axis of the absorbing polarizing film is preferably 90°±8° in the in-plane direction, more preferably 90°±4°, and more preferably 90°±2° with respect to the direction in which the roll is transported.

The method of continuously forming the absorbing polarizing film on the reflective polarizing plate, specifically, is preferably produced by a method including the following steps 1 to 7.

Step 1. Roll out a roll-shaped reflective polarizer on one side, and continuously coat the composition containing polymers and solvents that generate alignment constraints by light on the surface of the aforementioned roll-shaped reflective polarizer to form the first The step of coating film; Step 2. The step of heating and drying the aforementioned first coating film to form a first dry film; Step 3. The step of irradiating polarized ultraviolet rays on the aforementioned first dry film to form an alignment film; Step 4. A step of coating a composition containing a dichroic pigment, a polymerizable liquid crystal compound, a polymerization initiator, and a solvent on the aforementioned alignment film to form a second coating film; step 5. heating and drying the aforementioned second coating film to form The step of the second drying film; step 6. irradiating ultraviolet rays on the aforementioned second drying film to polymerize the polymerizable liquid crystal compound to form an absorbing polarizing film to form a composite polarizing plate; and step 7. rolling the aforementioned composite polarizing plate The step of winding to the roller.

The obtained roll-shaped composite polarizer is generally cut into a rectangle to form a single composite polarizer sheet. As mentioned above, the present invention is suitable for producing a large single-piece composite polarizer sheet having a penetration axis in the longitudinal direction. Specifically, it is suitable for making rectangular composite polarizing plates with a diagonal of more than 60 inches, preferably more than 80 inches, and more preferably more than 100 inches.

[Liquid crystal display device]

The composite polarizing plate of the present invention, which is provided with a polarizing film coated with a composition for forming an absorbing polarizing film on a reflective polarizing plate, can be placed between the backlight unit and the liquid crystal unit of a liquid crystal display device, and in The reflective polarizer surface is disposed on the backlight unit side, and the absorbing polarizing film formed by coating the absorbing polarizing film-forming composition containing dichroic pigments on the liquid crystal cell side is preferably used. In addition, the composite polarizing plate obtained in such a strip form has no joints and can be preferably applied to large liquid crystal displays.

In the liquid crystal unit formed with the composite polarizing plate of the present invention, the driving method of the liquid crystal unit can also be used in any known way, preferably including lateral electric field effect (IPS: In-Plane Switching), vertical distribution Phase (VA: Vertical Alignment) mode.

[Example]

Hereinafter, the present invention will be described in more detail through examples. "%" and "parts" in the examples refer to mass % and mass parts unless otherwise specified.

Example 1 [Manufacture of composition for photoalignment film formation]

The following components were mixed, and the resulting mixture was stirred at 80° C. for 1 hour, whereby a photoalignment film-forming composition was obtained.

Photoalignment material (2 parts):

Solvent (98 parts): o-xylene

[Manufacture of composition for polarizing film formation]

The following components were mixed and stirred at 80° C. for 1 hour to obtain a composition for forming a polarizing film. As the dichroic dye, the azo dye described in the Examples of JP-A-2015-165302 was used.

[Polymerizable liquid crystal compound]

[Dichroic pigment]

[other ingredients]

Polymerization initiator; 2-dimethylamino-2-benzyl-1-(4-morpholinylphenyl)butan-1-one (Irgacure 369; manufactured by Ciba Specialty Chemicals) 6 parts homogenizer ; polyacrylate compound (BYK-361N; manufactured by BYK-Chemie) 1.2 parts solvent; 250 parts o-xylene

[Measurement of Phase Transition Temperature]

A 2% by mass aqueous solution (composition for forming an alignment layer) of polyvinyl alcohol (polyvinyl alcohol 1000 complete saponification type, manufactured by Wako Pure Chemical Industries, Ltd.) was applied on a glass substrate by the spin coating method, and dried Thereafter, a film having a thickness of 100 nm was formed. Next, the surface of the obtained film was rubbed to form an alignment layer. For friction treatment, a semi-automatic friction device (product name: LQ-008, manufactured by Changyang Engineering Co., Ltd.) is used to press the amount of cloth (product name: YA-20-RW, manufactured by Yoshikawa Chemical Co., Ltd.) 0.15mm, rotation speed 500rpm, 16.7mm/s conditions. By the spin coating method, the composition for forming a polarizing film is coated on the alignment film thus prepared, heated and dried on a hot plate at 120° C. for 1 minute, and then cooled rapidly to room temperature to form on the aforementioned alignment layer. Dry the lamination. After raising the temperature of the dried film to 120°C on a heating plate, the phase transition temperature was measured by observing with a polarizing microscope while the temperature was lowering. As a result, it was confirmed that the phase shifted to the nematic phase at 115°C, the phase shifted to the smectic A phase at 105°C, and the phase shifted to the smectic B phase at 74°C.

[X-ray diffraction measurement]

By the spin coating method, the composition for forming a polarizing film is coated on the previous alignment film, heated and dried on a hot plate at 120° C. for 1 minute, and then rapidly cooled to room temperature to form a dry layer on the aforementioned alignment layer. lamination. Next, using a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Electric Co., Ltd.), irradiate ultraviolet rays to the dry film at an exposure dose of 2000mJ/cm ² (based on 365nm), thereby polymerizing the dried film. The polymerizable liquid crystal compound is polymerized while maintaining the liquid crystal state of the aforementioned polymerizable liquid crystal compound, and a polarizing film is formed from the dried coating. When the thickness of the polarizing film at this time was measured with a laser microscope (OLS300 by Olympus Corporation), it was 1.7 micrometers. Using the X-ray diffraction device X'Pert PRO MPD (manufactured by Spectris Co., Ltd.), X-ray diffraction measurement was performed on this polarizing film in the same manner. As a result, the peak half-value width (FWHM) = about 0.312 was obtained around 2θ = 20.1° ° sharp diffraction peak. In addition, the same results were obtained under the incidence from the direction perpendicular to the rubbing. The order period (d) obtained from the peak position was about 4.4Å, and it was confirmed that a structure reflecting a higher-order smectic phase was formed.

2. Fabrication of Composite Polarizer

[Production of photo-alignment layer]

A long APF (manufactured by 3M Company (3M Sumitomo Co., Ltd. in Japan)) roll with a width of 800mm was used as a reflective polarizer, and one side was continuously pulled out, and the surface was treated with plasma at the same time. The slit coater discharged the composition for forming an optical alignment film at a flow rate of 30 ml/min, and formed a first coating film in a width of 750 mm at the center of the film. Then, it was transported in a ventilated drying oven set at 120° C. for 2 minutes to remove the solvent to form a first dry film. Next, irradiate the first dry film with polarized UV light at 90° to the longitudinal direction of the film at an intensity of 20 mJ/cm ² (based on 313 nm) to impart alignment constraints and form an elongated photo-alignment film.

[Production of composite polarizing plate]

Using a slit coater, the composition for forming a polarizing film was discharged onto the photo-alignment film at a flow rate of 77.2 ml/min to form a second coating film in a width of 750 mm in the center of the film.

Then, it was transported in a ventilated drying oven set at 120° C. for 2 minutes to remove the solvent and form a second dry film. Then, UV light was irradiated at room temperature at 1000 mJ/cm ² (based on 365 nm), so that the polymerizable liquid crystal compound contained in the second dry film was polymerized while maintaining the liquid crystal state, and a polarizing film was formed from the dry film. Then, it was continuously wound into a roll shape to obtain a 200 m long composite polarizing plate (1) having an absorption axis in a 90° direction. The thickness of the composite polarizing plate produced in this way was measured with a contact film thickness meter, and the film as a whole was 28 μm. In addition, after cutting the composite polarizing plate with a microtome, carbon vapor deposition is applied to the section, and the scanning electron microscope (STEM, field emission scanning electron microscope (FE-STEM), model "S-5500 ", manufactured by Hitachi, Ltd.), it was found that the film thickness of the photoalignment film was 100 nm, and the film thickness of the polarizing film was 3.5 μm.

[Evaluation of Composite Polarizer]

From the positions 3 m from the coating start and 3 m from the coating end of the obtained elongated composite polarizing plate, five pieces of 5 cm square were cut out in the width direction.

3. Determination of polarizing properties

In order to confirm the usefulness of the composite polarizing plate, the sensitivity-corrected polarization degree was measured as follows.

Using a device that mounted a jacket with a polarizing element on a spectrophotometer (UV-3150 manufactured by Shimadzu Corporation), the transmission in the transmission axis direction was measured by the double-beam method in the wavelength range from 380 nm to 780 nm. The transmittance (T ¹ ) and the transmittance in the direction of the absorption axis (T ² ). The jacket, the reference side is set with a mesh that filters out 50% of the light. The transmittance at each wavelength was calculated using the following formula (Formula 1), and the sensitivity was corrected using the 2-degree field of view (C light source) of JIS Z 8701 to calculate the sensitivity-corrected polarization degree (Ty). The degree of polarization at each wavelength was calculated using the following formula (Formula 2), and the sensitivity was corrected using the 2-degree field of view (C light source) of JIS Z 8701 to calculate the sensitivity-corrected degree of polarization (Py). In addition, the angle θ formed by the reflection axis of the reflective polarizing plate and the absorbing polarizing film is obtained by separating the reflective polarizing plate and the absorbing polarizing film from the composite polarizing plate, and using the same side as the reference side, using Oji Scientific Instruments Co., Ltd. The automatic birefringence meter "KOBRA-WPR" manufactured by Co., Ltd. measures the reflection axis of the reflective polarizer and the absorption axis of the absorbing polarizing film by the rotation detection photon method, and follows the following formula: θ=(reflective polarizer The reflection axis angle of the plate) - (the absorption axis angle of the absorbing polarizing film) is calculated. The results are shown in Table 1 and Table 2. The angle θ formed by the reflection axis of the reflective polarizer and the aforementioned absorbing polarizer film is 0°. In addition, the sensitivity-corrected polarization degree (Py) of the composite polarizing plate was 99.7%, which was confirmed to be significantly improved compared to the sensitivity-corrected polarization degree (Py) of 95.5% for APF alone. In addition, it was also confirmed that it was stable in the width direction and the conveyance direction.

Monomer penetration rate (%)=(T ¹ +T ² )/2 formula (1)

Degree of polarization (%)={(T ¹ -T ² )/(T ¹ +T ² )}×100 Formula (2)

Example 2

Except having changed the flow rate of the composition for polarizing film formation into 68.2 ml/min, it carried out similarly to Example 1, and produced the composite polarizing plate. The film thickness of the photo-alignment film was 100 nm, and the film thickness of the polarizing film was 3.1 μm. Table 2 shows the measurement results of the polarizing performance.

Example 3

A composite polarizing plate was fabricated in the same manner as in Example 2 except that θ was changed to 2°. Table 2 shows the measurement results of the polarizing performance.

Example 4

A composite polarizing plate was fabricated in the same manner as in Example 2 except that θ was changed to 4°. Table 2 shows the measurement results of the polarizing performance.

Example 5

A composite polarizing plate was produced in the same manner as in Example 2 except that θ was changed to 5°. Table 2 shows the measurement results of the polarizing performance.

Example 6

A composite polarizing plate was produced in the same manner as in Example 2 except that θ was changed to 7°. Table 2 shows the measurement results of the polarizing performance.

Example 7

A composite polarizing plate was produced in the same manner as in Example 2 except that θ was changed to 8°. Table 2 shows the measurement results of the polarizing performance.

Comparative example 1

A composite polarizing plate was produced in the same manner as in Example 2 except that θ was changed to 10°. Table 2 shows the measurement results of the polarizing performance.

[Industrial applicability]

The composite polarizing plate of the present invention can be preferably used in the manufacture of thin and high-performance liquid crystal display devices.

Claims (10)

A composite polarizing plate, which sequentially has an absorbing polarizing film, an alignment film for aligning the absorbing polarizing film, and a reflective polarizing plate, the absorbing polarizing film and the reflecting polarizing plate are respectively adjacent to the alignment film, and the reflective polarizing plate reflects The angle formed by the axis and the absorption axis of the absorbing polarizing film is 8° or less. The absorbing polarizing film is a polymer of a polymerizable liquid crystal compound aligned and fixed in the in-plane horizontal direction in the state of a smectic liquid crystal phase, and contains For dichroic pigments, the thickness of the aforementioned absorbing polarizing film is 5 μm or less. The composite polarizing plate as described in claim 1 of the patent application, wherein the aforementioned alignment film is an optical alignment film that generates an alignment restriction force by light. The composite polarizing plate as described in claim 1 of the patent application, wherein the polymerizable liquid crystal compound is a thermotropic liquid crystal compound. The composite polarizing plate according to claim 1, wherein the ratio of the dichroic dye in the polymer of the polymerizable liquid crystal compound is 20 parts by mass or less with respect to 100 parts by mass of the polymerizable liquid crystal compound. The composite polarizing plate as described in item 1 of the patent claims, wherein the absorbing polarizing film is a polarizing film having a Bragg peak in X-ray diffraction measurement. The composite polarizing plate as described in claim 1, wherein the reflective polarizing plate is a multi-layer laminate of at least two polymer materials with different refractive indices. The composite polarizing plate described in item 1 of the scope of the patent application, the composite polarizing plate is rectangular and has a transmission axis in the long side direction. A roll-shaped composite polarizing plate, which sequentially has an absorbing polarizing film, an alignment film for aligning the absorbing polarizing film, and a reflective polarizing plate, wherein the reflection axis of the reflective polarizing plate is 90°±in-plane relative to the conveying direction of the roll 8°, the absorption axis of the absorbing polarizing film is 90°±8° in-plane with respect to the conveying direction of the roller, and the angle formed by the reflection axis of the reflective polarizing plate and the absorbing axis of the absorbing polarizing film is 8° or less. A method for manufacturing a roll-shaped composite polarizing plate. The roll-shaped composite polarizing plate has an absorbing polarizing film, an alignment film for aligning the absorbing polarizing film, and a reflective polarizing plate in sequence. The manufacturing method includes the following steps 1 to 7: Step 1. Roll out a roll-shaped reflective polarizer on one side, and continuously coat a composition containing a polymer and a solvent that generates an alignment restriction force by light on the surface of the roll-shaped reflective polarizer to form a first The step of coating film; Step 2. The step of heating and drying the aforementioned first coating film to form a first dry film; Step 3. The step of irradiating polarized ultraviolet rays on the aforementioned first dry film to form an alignment film; Step 4. A step of coating a composition containing a dichroic pigment, a polymerizable liquid crystal compound, a polymerization initiator, and a solvent on the aforementioned alignment film to form a second coating film; step 5. heating and drying the aforementioned second coating film to form The step of the second drying film; Step 6. A step of irradiating ultraviolet rays on the second dry film to polymerize the polymerizable liquid crystal compound to form an absorbing polarizing film to form a composite polarizing plate; and Step 7. Winding the composite polarizing plate onto a roll. A liquid crystal display device, which is configured with a composite polarizing plate as described in any one of items 1 to 7 of the patent scope between the backlight unit and the liquid crystal unit, and a reflective polarizer surface is arranged on the backlight unit side, and the liquid crystal unit It is formed by disposing the absorbing polarizing film on the side.