CN102890302B - Polarizing film and TN mode liquid crystal display device - Google Patents

Abstract

The invention provides a polarizing film which can reduce unevenness of front contrast among TN mode liquid crystal display devices, and a TN mode liquid crystal display device using the polarizing film. The polarizing film has a polarizer, a protective film located on one side of the polarizer, and a phase difference film located on the other side, wherein an absorption axis of the polarizing film is in a 45-degree direction relative to an end face, the phase difference film is a film having cellulose acylates as main components, and when the coefficients of thermal expansion of the protective film in the MD direction and in the TD direction are set to be C1MD and C1TD respectively, and when the coefficients of thermal expansion of the phase difference film in the MD direction and in the TD direction is set to be C2MD and C2TD respectively, the following formulas (i) and (ii) are satisfied at the same time: (i) P=|C1MD/C1TD-C2MD/C2TD|, and when C2MD < C2TD, P=|C1TD/C1MD-C2TD/C2MD|, AND 0<P<=6.0; and (ii) Q=(C1MD-C2MD)*(C1TD-C2TD)<0.

Description

Polaroid and TN mode LCD

Technical field

The polaroid that the inequality that the present invention relates to front contrast is inhibited and employ the TN mode LCD of this polaroid.

Background technology

With various liquid crystal indicators such as universal in the purposes such as PC display, TV TN pattern, VA pattern, IPS patterns, and wide viewing angle is carried out to each pattern turn to object, propose the technology used as compensation film for angular field of view by various phase retardation film.

For the polaroid used in liquid crystal indicator, usually on a face of the polarizer with polarization property, be fitted with diaphragm by bond layer, another side is fitted with phase difference film (also having the situation being only diaphragm).As the starting material of the polarizer, mainly use polyvinyl alcohol (PVA) (below sometimes also referred to as PVA), by by after PVA film uniaxial tension with iodine or bitintability dyeing, or by carrying out stretching after dyeing and then being cross-linked with boron compound, thus form the polarizer.

As diaphragm, from optical clear and birefringence is little, surface smoothing, by aspects such as saponification process and the cementability of the polarizer to be made up of PVA are excellent, mainly use cellulose triacetate (below sometimes also referred to as TAC).

As phase retardation film, known by optical anisotropic layer stacked on cellulose acylate film or made by stretch processing, as the phase retardation film that other are useful, propose norbornene resin, polycarbonate resin equiphase difference film.

Along with popularizing of liquid crystal indicator, required display quality also becomes higher level, even notebook computer lamp small-scale liquid crystal device, for the user appreciating photograph image, also likes higher front contrast.

As the technology liquid crystal indicator of VA pattern being improved to front contrast, such as can enumerate Japanese Unexamined Patent Publication 2008-003126 publication, wherein, propose by the elastic modulus of film or hygroscopic expansion coefficient control polaroid amount of curl, improve front contrast.

On the other hand; in the small-sized liquid crystal indicator employing the TN mode liquid crystals such as notebook computer; as a rule; do not use phase retardation film; but be used in two side bonds of the polarizer polaroid of diaphragm, but also seek the visual angle of improving TN mode liquid crystal simply, about the technology at visual angle improving TN mode LCD; such as can enumerate Japanese Unexamined Patent Publication 2009-037231 publication, which propose the phase retardation film and light-diffusing films that use optics twin shaft.

Summary of the invention

Invent problem to be solved

When the visual angle in order to improve TN mode liquid crystal, when the cell side of polaroid adopts the phase retardation film of optics twin shaft, the problem of front contrast inequality can be produced between display device individuality.

Investigate this reason, found that, the axle precision when the panel of polaroid attaches is low corresponding with the inequality of front contrast.

The object of the invention is to, the polaroid of the inequality of the front contrast that can reduce between TN mode LCD individuality is provided and employs the TN mode LCD of this polaroid.

For the means of dealing with problems

Means for solving the problem are as described below.

[1] polaroid, is characterized in that, it possesses the polarizer, be positioned at the diaphragm of the side of the described polarizer and be positioned at the phase retardation film of opposite side of the described polarizer,

Wherein, the absorption axle of described polaroid is 45 degree of directions relative to end face,

Described phase retardation film is the film using cellulose acylate as principal ingredient,

C1 is set at the thermal expansivity in the MD direction by described diaphragm _mD, the thermal expansivity in TD direction is set to C1 _tD, and the thermal expansivity in the MD direction of described phase retardation film is set to C2 _mD, the thermal expansivity in TD direction is set to C2 _tDtime,

Meet following formula (i) and (ii) simultaneously:

I () is at C2 _mD>=C2 _tDtime, P=|C1 _mD/ C1 _tD-C2 _mD/ C2 _tD|,

At C2 _mD< C2 _tDtime, P=|C1 _tD/ C1 _mD-C2 _tD/ C2 _mD|,

0＜P≤6.0；

(ii)Q＝(C1 _MD－C2 _MD)×(C1 _TD－C2 _TD)＜0。

[2] polaroid of above-mentioned [1], wherein, the P in described (i) is 0.1 ~ 1.0.

[3] polaroid of above-mentioned [1] or [2], wherein, the Q in described (ii) is-5 ~-200.

[4] polaroid of above-mentioned [1], wherein, the P in described (i) is 0.1 ~ 1.0, and the Q in described (ii) is-5 ~-200.

[5] polaroid any one of above-mentioned [1] ~ [4], wherein, the C1 in described (i) and (ii) _mD, C1 _tD, C2 _mDand C2 _tDbe respectively 20 ~ 80ppm/ DEG C.

[6] polaroid any one of above-mentioned [1] ~ [5], wherein, the C1 in described (i) _mD/ C1 _tDbe 1.2 ~ 4.0.

[7] polaroid any one of above-mentioned [1] ~ [6], wherein, the C2 in described (i) _mD/ C2 _tDbe 1.8 ~ 4.0.

[8] polaroid any one of above-mentioned [1] ~ [7], wherein, described cellulose acylate is the total degree of substitution of acyl group is the cellulose acylate of 2.2 ~ 2.6.

[9] polaroid any one of above-mentioned [1] ~ [8], wherein, described cellulose acylate is the cellulose acetate propionate meeting following formula (1) and (2),

（1）2.2≤A+B≤2.6

（2）0.3≤B≤1.2

Wherein, A represents the degree of substitution of the acetyl group in cellulose acylate, and B represents the degree of substitution of the propiono in cellulose acylate.

[10] polaroid of above-mentioned [4], wherein, the C1 in described (i) _mD/ C1 _tDbe 1.2 ~ 4.0, the C2 in described (i) _mD/ C2 _tDbe 1.8 ~ 4.0, described cellulose acylate is the cellulose acetate propionate meeting following formula (1) and (2),

（1）2.2≤A+B≤2.6

（2）0.3≤B≤1.2

Wherein, A represents the degree of substitution of the acetyl group in cellulose acylate, and B represents the degree of substitution of the propiono in cellulose acylate.

[11] a TN mode LCD, it has [1] ~ [10] any one of polaroid.

Invention effect

According to the present invention, the polaroid of the inequality of the front contrast that can reduce between TN mode LCD individuality can be provided and employ the TN mode LCD of this polaroid.Specifically, the curling of polaroid when fitting to liquid crystal cells can be reduced, reduce axle offset during laminating, prevent the reduction of front contrast.

Accompanying drawing explanation

Fig. 1 is the diagrammatic cross-section of an example of TN mode LCD of the present invention.

Embodiment

Below list embodiments of the present invention to be described in detail.In addition, refer to by the numerical range that " ~ " represents in this instructions and comprise the numerical value recorded before and after it scope as lower limit and higher limit.

First, the term adopted in this instructions is described.

Re(λ), Rth(λ) represent under wavelength X face respectively in the delay of delay and thickness direction.Re(λ) be measure machine Co., Ltd. system KOBRA21ADH or WR(prince) in, the normal direction incident wavelength along film is that the light of λ nm measures.When selecting to measure wavelength X nm, manually can change wavelength selective filters or being measured by conversion measured values such as programs.When measured film represents with the indicatrix of single shaft or twin shaft, calculate Rth(λ by following method).

Relative to using the slow axis (being judged by KOBRA21ADH or WR) in face as sloping shaft (turning axle) (when there is no slow axis, using the arbitrary direction in face as turning axle) film normal direction, from normal direction play one-sided 50 ° with 10 degree for interval is respectively from the light that the direction incident wavelength of this inclination is λ nm, measure the above-mentioned Re(λ of whole 6), based on the length of delay of this mensuration and the default of mean refractive index and the film thickness value that inputs, calculate Rth(λ by KOBRA21ADH or WR).In above-mentioned, when from normal direction using the slow axis in face as turning axle and there is at certain angle of inclination the film in the direction of the value vanishing of delay, for the length of delay under the angle of inclination being greater than this angle of inclination, by its variation of sign for after negative, calculated by KOBRA21ADH or WR.In addition, can using slow axis as sloping shaft (turning axle) (when there is no slow axis yet, using the arbitrary direction in face as turning axle), from 2 direction detection length of delays of arbitrary inclination, based on default and the film thickness value that inputs of this value and mean refractive index, calculate Rth by following formula (A) and formula (B).

$\mathrm{Re}\left(\mathrm{\&theta;}\right)=[\mathrm{nx}-\frac{\mathrm{ny}\&times;\mathrm{nz}}{\sqrt{{\{\mathrm{ny}\sin \left({\sin }^{-1}\left(\frac{\sin (-\mathrm{\&theta;})}{\mathrm{nx}}\right)\right)\}}^2+{\{\mathrm{nz}\cos \left({\sin }^{-1}\left(\frac{\sin (-\mathrm{\&theta;})}{\mathrm{nx}}\right)\right)\}}^2}}]\&times;\frac{d}{\cos \left\{{\sin }^{-1}\left(\frac{\sin (-\mathrm{\&theta;})}{\mathrm{nx}}\right)\right\}}$ Formula (A)

In addition, above-mentioned Re(θ) represent from the length of delay in the direction of normal direction tilt angle theta.In addition, the refractive index of the slow-axis direction in the nx presentation surface in formula (A), ny represents the refractive index in direction orthogonal with nx in face, and nz represents the refractive index in the direction orthogonal with nx and ny.D represents the thickness measuring film.

Rth=((nx+ny)/2-nz) × d formula (B)

When measured film be can not with the indicatrix performance of single shaft or twin shaft, the film that do not have so-called optic axis (optic axis), calculate Rth(λ by following method).Using the slow axis (being judged by KOBRA21ADH or WR) in face as sloping shaft (turning axle), be that interval is respectively from the light that the direction incident wavelength of this inclination is λ nm with 10 ° relative to film normal direction to+50 ° from-50 °, measure the above-mentioned Re(λ of 11), based on the length of delay of this mensuration and the default of mean refractive index and the film thickness value that inputs, calculate Rth(λ by KOBRA21ADH or WR).In addition, in above-mentioned mensuration, the default of mean refractive index can use the value of the goods catalogue of polymer handbook (JOHN WILEY & SONS, INC), various blooming.For the film of value of still not knowing mean refractive index, can measure with Abbe refractometer.The value of the mean refractive index of main blooming is illustrated as follows: cellulose acylate (1.48), cyclic olefin polymer (1.52), polycarbonate (1.59), polymethylmethacrylate (1.49), polystyrene (1.59).By inputting default and the thickness of these mean refractive indexs, calculate nx, ny, nz by KOBRA21ADH or WR.Nx, ny, nz of being calculated by this, calculate Nz=(nx-nz further)/(nx-ny).

In this instructions, " parallel ", " orthogonal " refer in the scope lower than strict angle ± 10 °.The error of this scope and strict angle is preferably lower than ± 5 °, is more preferably lower than ± 2 °.In addition, " slow axis " refers to the direction that refractive index reaches maximum.

In addition, as long as no specifying, the mensuration wavelength of refractive index is exactly the value under the λ=550nm of visible region, about the mensuration wavelength of Re and Rth, as long as no specifying, is then set as 550nm.

In addition, in this manual, MD direction represents film throughput direction, and TD direction represents the direction orthogonal with MD direction.Wherein, in the present invention, phase retardation film is consistent with the MD direction of diaphragm and the absorption axle of polaroid.

The present invention is a kind of polaroid, it is characterized in that, it possesses the polarizer, be positioned at the diaphragm of the side of the described polarizer and be positioned at the phase retardation film of opposite side of the described polarizer,

Wherein, the absorption axle of described polaroid is 45 degree of directions relative to end face,

Described phase retardation film is the film using cellulose acylate as principal ingredient,

C1 is set at the thermal expansivity in the MD direction by described diaphragm _mD, the thermal expansivity in TD direction is set to C1 _tD, and the thermal expansivity in the MD direction of described phase retardation film is set to C2 _mD, the thermal expansivity in TD direction is set to C2 _tDtime,

Meet following formula (i) and (ii) simultaneously:

I () is at C2 _mD>=C2 _tDtime, P=|C1 _mD/ C1 _tD-C2 _mD/ C2 _tD|,

At C2 _mD< C2 _tDtime, P=|C1 _tD/ C1 _mD-C2 _tD/ C2 _mD|,

0＜P≤6.0；

(ii)Q＝(C1 _MD－C2 _MD)×(C1 _TD－C2 _TD)＜0。

Below, the various components used in the present invention are described.

" phase retardation film "

< cellulose acylate film >

In the present invention; preferably contain cellulose acylate as principal ingredient; in described cellulose acylate, the total degree of substitution of acyl group to the hydroxyl of the glucose unit of formation cellulose acylate is 2.2 ~ 2.6, is particularly preferably the cellulose acetate propionate meeting following formula (1) and (2).

（1）2.2≤A+B≤2.6

（2）0.3≤B≤1.2

Wherein, A refers to the degree of substitution of the acetyl group in cellulose acylate, and B refers to the degree of substitution of the propiono in cellulose acylate.

In this instructions; so-called " containing ... as principal ingredient ", when the cellulose acylate of the materials'use as film is a kind, refer to this cellulose acylate; when the cellulose acylate of the materials'use as film is multiple, refer to the cellulose acylate contained the most at high proportion.In cellulose, the glucose unit of each β-Isosorbide-5-Nitrae bonding has free hydroxyl 2,3 and 6.The cellulose acylate used in the present invention is that the hydrogen atom of average 2.2 ~ 2.6 hydroxyls in these 3 hydroxyls is replaced by acetyl group or propiono and the wherein cellulose acetate propionate that replaced by propiono of the hydrogen atom of 0.6 ~ 1.1 hydroxyl.

In addition, in this instructions, the acetyl group in cellulose and propiono degree of substitution separately can be calculated by the bonding fatty acid amount measuring cellulosic Component units unit mass.Assay method is implemented according to " ASTM D817-91 ".

As the cellulose of cellulose acetate propionate raw material, there are cotton linter or wood pulp (broad leaf tree paper pulp, conifer paper pulp) etc., the cellulose acylate obtained by any raw cellulose can be used, also can be according to circumstances used in combination.About the detailed record of these raw celluloses, such as can use ball pool, (cellulose recorded in the public skill No. 2001-1745, designation (7 pages ~ 8 pages) of distribution) Huo Development Ming Association Hui Gong Open skill Reported for 1970, is not particularly limited the new Wen society of space field work " プ ラ ス チ Star Network Cai Liao Talk seat (17) Xian Victoria prime system Trees fat " daily magazine industry.

Above-mentioned cellulose acetate propionate preferably has the equal degree of polymerization of matter of 350 ~ 800, preferably has the equal degree of polymerization of matter of 370 ~ 600 further.In addition the cellulose acetate propionate used in the present invention preferably has the number-average molecular weight of 70000 ~ 230000, preferably has the number-average molecular weight of 75000 ~ 230000 further, further preferably has the number-average molecular weight of 78000 ~ 120000.

Above-mentioned cellulose acetate propionate can use acid anhydrides or acyl chlorides to synthesize as acylating agent.As the most general industrial synthetic method, as described below.The mixed organic acid composition of the cellulose obtained by cotton linter or wood pulp etc. containing the organic acid (acetic acid, propionic acid) corresponding with acetyl group and propiono or their acid anhydrides (acetic anhydride, propionic andydride) is carried out esterification, the cellulose acetate propionate of target can be synthesized.

< adjuvant >

The phase retardation film used in the present invention while containing the cellulose acetate propionate as principal ingredient, can contain at least a kind of adjuvant according to various object.When manufacturing this phase retardation film by solution film-forming method, these adjuvants can add in cellulose acetate propionate rubber cement.The opportunity of adding is not particularly limited.Adjuvant is selected from the adjuvant of compatible with cellulose acetate propionate (dissolving in solution film-forming method in cellulose acetate propionate rubber cement).Adjuvant is by the optical characteristics adjusting cellulose acetate propionate and adjusts for the purpose of other characteristic etc. and add.

< plastifier >

Above-mentioned phase retardation film contains plastifier, can improve masking etc., so preferably.Wherein, contracting Polyester plastifier is used to be preferred from the viewpoint of birefringent embodiment.Contracting Polyester plastifier can be selected from the condensed polymer of dicarboxylic acid and glycol.Contracting Polyester plastifier is not particularly limited, but preferably in molecule, has the contracting Polyester plastifier of aromatic rings, more preferably has the contracting Polyester plastifier of phenyl ring.Wherein, preferably select from the condensed polymer of aromatic dicarboxylic acid and aliphatic diol.Aromatic dicarboxylic acid and aliphatic diol can be a kind respectively, also can be two or more.

In the example of above-mentioned aromatic dicarboxylic acid, comprise the arlydene dicarboxylic acid that the carbon numbers such as phthalic acid, terephthalic acid (TPA), m-phthalic acid, 1,5-naphthalene dicarboxylic acids, Isosorbide-5-Nitrae-naphthalene dicarboxylic acids are 6 ~ 12.Wherein, if use dicarboxylic acid component to be terephthalic acid (TPA) etc. in contraposition to have the contracting Polyester plastifier of the benzene derivative of 2 carboxylic acids, then birefringent embodiment uprises, so preferably.

In the example of above-mentioned aliphatic diol, comprise the aklylene glycol that carbon number is 2 ~ 12, specifically, comprise ethylene glycol, 1, 2-propylene glycol, 1, ammediol, 1, 2-butylene glycol, 1, 3-butylene glycol, 1, 2-propylene glycol, 2-methyl isophthalic acid, ammediol, 1, 4-butylene glycol, 1, 5-pentanediol, 2, 2-dimethyl-1, ammediol (neopentyl glycol), 2, 2-diethyl-1, ammediol (3, 3-dihydroxymethyl pentane), 2-normal-butyl-2-ethyl-1, ammediol (3, 3-dihydroxymethyl heptane), 3-methyl isophthalic acid, 5-pentanediol, 1, 6-hexanediol, 2, 2, 4-trimethyl-1, 3-pentanediol, 2-ethyl-1, 3-hexanediol, 2-methyl isophthalic acid, 8-ethohexadiol, 1, 9-nonanediol, 1, 10-decanediol, 1, 12-octacosanol etc.These glycol can use a kind or use as potpourri of more than two kinds.

In the present invention, the hydroxyl of the preferred end of utilizable contracting Polyester plastifier is by end-blocking.End-blocking can use aromatic series monocarboxylic acid, wherein, preferably uses and can have substituent benzene monocarboxylic acid.As concrete example, benzoic acid, p-tert-butyl benzoic acid, o-toluic acid, m-methyl benzoic acid, p-methylbenzoic acid, mesitylenic acid, ethyl benzoate, n-propylbenzene formic acid, aminobenzoic acid, acetoxy-benzoic acid etc. can be listed.They can use a kind or use as potpourri of more than two kinds respectively.

Below, the object lesson of utilizable contracting Polyester plastifier in the present invention is shown, but is not limited to following object lesson.

Table 1

The number-average molecular weight of the contracting Polyester plastifier that can use is preferably 300 ~ 2000, is more preferably the scope of 400 ~ 1500.In addition, its acid number is below 0.5mgKOH/g, hydroxyl value is below 25mgKOH/g, and more preferably acid number is below 0.3mgKOH/g, hydroxyl value is below 15mgKOH/g.

The addition of above-mentioned contracting Polyester plastifier is preferably 1 ~ 25 quality % relative to cellulose acylate, is more preferably 2 ~ 15 quality %.But, be not limited to this scope.

As utilizable preferred plastifier in the present invention than that described above, the plastifier of carbohydrates system can be listed, be the derivant of monose or the carbohydrates comprising 2 ~ 10 monosaccharide units, the group (such as hydroxyl, carboxyl, amino, sulfydryl etc.) that can replace in these monose or the preferred molecule of polysaccharide is substituted.

The alternatively example of base, can list ether, ester group, amide group, imide etc.

As monose or the example of carbohydrates comprising 2 ~ 10 monosaccharide units, include, for example out erythrose, threose, ribose, arabinose, wood sugar, lyxose, allose, altrose, glucose, fructose, mannose, gulose, idose, galactose, talose, trehalose, isotrehalose, neotrehalose, mycosamine, kojibiose, black mould sugar, maltose, maltitol, isomaltose, sophorose, laminaribiose, cellobiose, gentiobiose, lactose, lactose amine, lactitol, lettuce disaccharides, melibiose, primeverose, rutinose, scillabiose, sucrose, Sucralose, turanose, vicianose, cellotriose, chacotriose, gentianose, Isomaltotriose, isopanose, maltotriose, manninotriose, melezitose, glucityl maltose, plantain seed sugar, gossypose, solatriose, umbelliferose, lycotetraose, maltotetraose, stachyose, maltopentaose, verbascose, MALTOHAXAOASE, alpha-cyclodextrin, beta-schardinger dextrin-, gamma-cyclodextrin, δ-cyclodextrin, xylitol, D-sorbite etc.

Be preferably ribose, arabinose, wood sugar, lyxose, glucose, fructose, mannose, galactose, trehalose, maltose, cellobiose, lactose, sucrose, Sucralose, alpha-cyclodextrin, beta-schardinger dextrin-, gamma-cyclodextrin, δ-cyclodextrin, xylitol, D-sorbite, more preferably arabinose, wood sugar, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, beta-schardinger dextrin-, gamma-cyclodextrin, be particularly preferably wood sugar, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, xylitol, D-sorbite.

In addition, as the substituent example of carbohydrates system plastifier, (preferred carbon number is 1 ~ 22 can to list ether, more preferably carbon number is 1 ~ 12, particularly preferably carbon number is the alkylether radicals of 1 ~ 8, such as methyl ether, ethyl ether, propyl group ether, hydroxyethyl ether, hydroxypropyl ether groups, 2-cyano ethyl ether, phenyl ether, benzyl ether etc.), (preferred carbon number is 1 ~ 22 to ester group, more preferably carbon number is 2 ~ 12, particularly preferably carbon number is the acyl ester group of 2 ~ 8, such as acetyl group, propiono, bytyry, valeryl, caproyl, caprylyl, benzoyl, toluyl groups, phthalyl etc.), (preferred carbon number is 1 ~ 22 to amide group, more preferably carbon number is 2 ~ 12, particularly preferably carbon number is the acid amides of 2 ~ 8, such as formamido, acetamido etc.), (preferred carbon number is 4 ~ 22 to imide, more preferably carbon number is 4 ~ 12, particularly preferably carbon number is the imide of 4 ~ 8, such as succinimido, phthalimide-based etc.).

In these substituting groups, more preferably ether or ester group, be particularly preferably ester group.

As the preference of carbohydrates system plastifier, following example can be listed.But operable carbohydrates system plastifier is not limited to these in the present invention.

That is, xylose tetraacetate is preferably, alpha-glucose pentaacetate, fructose pentaacetate, Mannose pentaacetate, galactose pentaacetate, maltose octaacetate, cellobiose octaacetate, sucrose octaacetate, xylitol pentaacetate, sorbitol hexaacetate, wood sugar four propionic ester, glucose pentapropiopanoate, fructose five propionic ester, mannose five propionic ester, galactose five propionic ester, maltose eight propionic ester, cellobiose eight propionic ester, sucrose octapropanoate, xylitol five propionic ester, D-sorbite six propionic ester, wood sugar four butyric ester, Glucose Pentabutyrate, fructose five butyric ester, mannose five butyric ester, galactose five butyric ester, maltose eight butyric ester, cellobiose eight butyric ester, sucrose eight butyric ester, xylitol five butyric ester, D-sorbite six butyric ester, wood sugar four benzoic ether, glucose pentaphene formic ether, fructose pentaphene formic ether, mannose pentaphene formic ether, galactose pentaphene formic ether, maltose eight benzoic ether, cellobiose eight benzoic ether, sucrose eight benzoic ether, xylitol pentaphene formic ether, D-sorbite six benzoic ether etc., more preferably xylose tetraacetate, alpha-glucose pentaacetate, fructose pentaacetate, Mannose pentaacetate, galactose pentaacetate, maltose octaacetate, cellobiose octaacetate, sucrose octaacetate, xylitol pentaacetate, sorbitol hexaacetate, wood sugar four propionic ester, glucose pentapropiopanoate, fructose five propionic ester, mannose five propionic ester, galactose five propionic ester, maltose eight propionic ester, cellobiose eight propionic ester, sucrose octapropanoate, xylitol five propionic ester, D-sorbite six propionic ester, wood sugar four benzoic ether, glucose pentaphene formic ether, fructose pentaphene formic ether, mannose pentaphene formic ether, galactose pentaphene formic ether, maltose eight benzoic ether, cellobiose eight benzoic ether, sucrose eight benzoic ether, xylitol pentaphene formic ether, D-sorbite six benzoic ethers etc., are particularly preferably maltose octaacetate, cellobiose octaacetate, sucrose octaacetate, wood sugar four propionic ester, glucose pentapropiopanoate, fructose five propionic ester, mannose five propionic ester, galactose five propionic ester, maltose eight propionic ester, cellobiose eight propionic ester, sucrose octapropanoate, wood sugar four benzoic ether, glucose pentaphene formic ether, fructose pentaphene formic ether, mannose pentaphene formic ether, galactose pentaphene formic ether, maltose eight benzoic ether, cellobiose eight benzoic ether, sucrose eight benzoic ether, xylitol pentaphene formic ether, D-sorbite six benzoic ether etc.

Above-mentioned phase retardation film also containing other plastifier, such as, can contain at least a kind of other plastifier selected from polyol ester system plastifier, carbohydrate system plastifier and phosphate plasticizer etc.About object lesson, on the books in the publications such as No. 2010-079241, Japanese Unexamined Patent Publication and No. 2007-169592, Japanese Unexamined Patent Publication.

In addition, above-mentioned phase retardation film also containing other adjuvant, also can contain more than a kind of the various adjuvants such as particulate, anti-deterioration agent, remover, optical characteristics correctives.The example of these adjuvants is on the books in Japanese Unexamined Patent Publication 2010-079241 publication, can reference.

In addition, the content comprising the total of whole adjuvants of plastifier is preferably below 25 quality % relative to cellulose acetate propionate.

Film-forming method for above-mentioned phase retardation film is not particularly limited.Any one in solution film-forming method and melting masking method all can utilize.Preferably by the film that solution film-forming method (solvent cast method) masking obtains.In solvent cast method, the cellulose acetate propionate of regulation is dissolved in organic solvent and is modulated into rubber cement, by the surface of rubber cement curtain coating to the supporter formed by metal etc., dry and masking, then, film is stripped from supporting body surface, carries out stretch processing (such as biaxial stretch-formed process) according to expectation, manufacture thus.About solvent cast method, on the books in various document, can reference.Such as, can with reference to the record in [0064] of Japanese Unexamined Patent Publication 2010-079241 publication ~ [0079].

< stretching >

Above-mentioned phase retardation film also can be have adjusted its film postponed by stretch processing.Stretch processing can be carried out in film-forming process, also can carry out after masking.Film be stretching in normal temperature or heating condition under implement.Before and after the glass transition temperature that heating-up temperature is preferably film ± 20 DEG C.This is because, if stretched with the temperature more much lower than glass transition temperature, then easily rupture, desired optical characteristics cannot be embodied.In addition, if stretched with the temperature more much higher than glass transition temperature, then the film that molecular orientation occurs by stretching before by heat fixation, relax because of heat when stretching, cannot by orientation immobilization, the manifesting property variation of optical characteristics.

The stretching of film preferably carries out uniaxial tension along TD direction.The stretching ratio in TD direction is preferably 1.1 times ~ 2 times, preferably carries out stretch processing with the stretching ratio of 1.1 ~ 1.6 times.

< surface treatment >

Also surface treatment can be implemented to the phase retardation film made like this.In surface-treated example, Corona discharge Treatment, glow discharge process, flame treatment, acid treatment, alkali treatment or Ultraviolet radiation process can be listed.In addition, also preferably undercoat is set as recorded in Japanese Unexamined Patent Publication 7-333433 publication.When the surface being fitted in the polarizer uses as diaphragm, from the view point of the cementability with the polarizer, particularly preferably implement acid treatment or alkali treatment and saponification process.The surface energy of above-mentioned phase retardation film is preferably more than 55mN/m, is more preferably more than 60mN/m and below 75mN/m.

< optical characteristics >

For the phase differential of phase retardation film utilizable in the present invention, Re(550 is postponed in face preferably under wavelength 550nm) be 20 ~ 80nm, and thickness direction retardation Rth(550 at that wavelength) be 100 ~ 180nm, more preferably Re(550) be 30 ~ 60nm, Rth(550) be 110 ~ 160nm.

" polaroid "

As the polarizer used in the present invention (polarizing coating), be not particularly limited.Such as, the polarizer etc. being impregnated into by polyvinyl alcohol film and carrying out in iodine solution stretching can be used.As the bonding agent used when above-mentioned phase retardation film and the polarizer being fitted, the latex of the aqueous solution of polyvinyl alcohol (PVA) or Pioloform, polyvinyl acetal (such as polyvinyl butyral), vinyl polymers (such as butyl polyacrylate) can be used.Particularly preferred bonding agent is the aqueous solution of fully saponified polyvinyl alcohol (PVA).

The thickness of the polarizer is preferably 5 ~ 30 μm, is particularly preferably 10 ~ 25 μm.

About the diaphragm on another surface (becoming the surface in the outside of the polarizer when being namely assembled in liquid crystal indicator) being fitted in the polarizer; various polymer film can be utilized, the styrenics etc. such as the acrylic acid series polymeric compounds such as Polyester polymkeric substance, polymethylmethacrylate such as such as cellulose acylate, polycarbonate based polymer, polyethylene terephthalate or PEN, polystyrene or acrylonitritrile-styrene resin (AS resin).In addition, can from tygon, the polyolefin such as polypropylene, the cyclopolyolefins such as norborene, polyolefin polymkeric substance as ethylene-propylene copolymer, vinyl chloride-based polymer, the acid amides such as nylon or aromatic polyamide based polymer, imide series polymkeric substance, sulfone based polymer, polyethersulfone based polymer, polyetheretherketone based polymer, polyphenylene sulfide based polymer, vinylidene chloride based polymer, vinyl alcohol based polymer, vinyl butyral based polymer, arylide based polymer, polyoxymethylene based polymer, epoxy polymkeric substance, or select one kind or two or more polymkeric substance in the polymkeric substance etc. being mixed with above-mentioned polymkeric substance, make for making polymer film as principal ingredient, as diaphragm.In addition the polymer film of general commercially available product can also be used.

Wherein especially preferred cellulose acylate film, particularly preferably tri cellulose acetate membrane.

The feature of polaroid of the present invention is, the thermal expansivity of diaphragm is being set to C1 _mD, C1 _tD, and the thermal expansivity of described phase retardation film is set to C2 _mD, C2 _tDtime, meet following formula (i) and (ii) simultaneously:

I () is at C2 _mD>=C2 _tDtime, P=|C1 _mD/ C1 _tD-C2 _mD/ C2 _tD|,

At C2 _mD< C2 _tDtime, P=|C1 _tD/ C1 _mD-C2 _tD/ C2 _mD|,

0＜P≤6.0；

(ii)Q＝(C1 _MD－C2 _MD)×(C1 _TD－C2 _TD)＜0。

The C1 of diaphragm _mD, C1 _tDand the C2 of phase retardation film _mD, C2 _tDvalue can be controlled by the principal ingredient of polymkeric substance and length growth rate, when each value is when the scope of 5 ~ 100ppm/ DEG C, the curling this point of calm polaroid easy to control is set out preferably, the particularly preferably scope of 20 ~ 80ppm/ DEG C.

The present invention passes through anisotropy and the C1 of the thermal expansivity of Control protection film _mD/ C1 _tD, and the anisotropy of thermal expansivity of phase retardation film and C2 _mD/ C2 _tDprevent the curling of polaroid, above-mentioned P value is greater than 0 and the scope of less than 6.0.

In the present invention, when diaphragm and phase retardation film are same film or when there is identical thermal expansivity characteristic, effect of the present invention can not be played, but contrary to C1 _mD/ C1 _tDand C2 _mD/ C2 _tDwhen for numerical value that difference is larger, the curling control of polaroid also becomes difficulty.Therefore, P value range preferably from 0.005 ~ 6.0, be more preferably 0.01 ~ 3.0, most preferably be 0.1 ~ 1.0.

About phase retardation film, C2 _mD/ C2 _tDbe preferably 1.2 ~ 5.0 with numerical value larger in the value of its inverse, be more preferably 1.5 ~ 4.5, most preferably be 1.8 ~ 4.0.

About diaphragm, C1 _mD/ C1 _tDbe preferably 1.0 ~ 5.0 with numerical value larger in the value of its inverse, be more preferably 1.1 ~ 4.5, most preferably be 1.2 ~ 4.0.Ratio controls by the stretching in MD direction or TD direction.

In addition, Q value of the present invention represents with the long-pending form of the different value of symbol, and it is meant to, and makes the weak curling relative to the reverse generation of plane of the polaroid on weak curling and orthogonal with it the TD direction of the polaroid on MD direction, thus overallly keeps flat condition.Q value is for time negative, and what heat drying when polaroid makes caused curlingly can not occur, and can prevent polaroid spool through time volume pleat, what prevent the contraction of the polarizer from causing is curling etc., and all reasons curling to polaroid play Anti-curling effects.

Q value is negative value, is preferably-0.1 ~-500, is more preferably-1 ~-400, most preferably is-5 ~-200.

If the absolute value of Q value is excessive, then polaroid is difficult to maintain smooth state, if the absolute value of long-pending value is too small, then to polaroid spool through time volume pleat preventing effectiveness, the curling preventing effectiveness that the contraction of the polarizer causes is died down.

The absorption axle of polaroid is 45 degree of directions relative to end face.That is, the long limit of polaroid or the absorption axle angulation of minor face and the polarizer are 45 degree of directions.

About the diaphragm of outer surface being fitted in the polarizer, preferably in face in slow axis and face fast axle all directions on tensile modulus of elasticity be that 3.5 ~ 6.0GPa(is more preferably 4.0 ~ 6.0GPa).

< crimp values >

The crimp values of the phase retardation film that can utilize in the present invention can measure as follows: by each polaroid cut from the square of 300mm × 300mm; according to diaphragm side under mode be set to the state of horizontal; 25 DEG C, place more than 2 hours under the environment of 50%RH after; measure the float length that anomaly puts platform, this measured value is the crimp values of phase retardation film.

When crimp values is within 30mm, when polaroid being attached to TN mode liquid crystal, there is no being involved in of air, thus preferably, within 10mm.

An example of the manufacture method of polaroid of the present invention at least comprises following operation: obtain the operation of duplexer by making the polarizer of strip, phase retardation film and diaphragm respectively according to making the consistent mode of respective length direction fit.The polarizer being made into strip has absorption axle along its length usually, and in addition, the phase retardation film carrying out stretch processing along MD direction or TD direction has slow axis in the face parallel or orthogonal with length direction usually.By by making length direction as one man stacked, above-mentioned duplexer that is that obtain is cut into and has on one side rectangular-shaped in the direction relative to length direction being 45 °, can easily make following polaroid: the absorption axle angulation of its long limit or minor face and the polarizer is 45 °, and the slow axis of phase retardation film is parallel or orthogonal with the absorption axle of the above-mentioned polarizer.And then, above-mentioned phase retardation film and diaphragm due to the thermal expansivity on TD direction and MD direction within the limits prescribed, the curling generation of polaroid can be reduced, reduce axle offset during laminating, suppress front contrast to reduce.

" liquid crystal indicator "

Polaroid of the present invention may be used in liquid crystal indicator, is preferred in the liquid crystal indicator of TN pattern.Fig. 1 represents the diagrammatic cross-section of an example of TN mode LCD of the present invention.In addition, in figure, the relativeness of the thickness of each layer is not necessarily consistent with the relativeness of each layer thickness of the liquid crystal indicator of reality.

TN mode LCD shown in Fig. 1 possesses the backlight BL of polaroid of the present invention i.e. a pair viewable side polaroid PL1 and backlight side polaroid PL2, the TN mode liquid crystal cell LC configured and the more lateral that is positioned at the backlight side polarizer 18 therebetween.

The respective axis of homology of the polarizer 16 and 18 is orthogonal, and or 135 ° ground configurations at 45 ° relative to display surface horizontal direction (sometimes also referred to as 0 ° of direction).In one example in which, the axis of homology of the polarizer 16 is parallel with the friction mandrel of substrate 12, and the axis of homology of the polarizer 18 is parallel with the friction mandrel of substrate 14, in another example, the axis of homology of the polarizer 16 is orthogonal with the friction mandrel of substrate 12, and the axis of homology of the polarizer 18 is orthogonal with the friction mandrel of substrate 14.

The liquid crystal layer 10 containing nematic liquid crystal material that liquid crystal cells LC has a pair substrate 12 and 14 and configures therebetween.Have friction orientation film (not shown) in the internal surface configurations of substrate 12 and 14, the orientation of nematic liquid crystal control by respective frictional direction, twist orientation.In addition, be formed with electrode layer (not shown) at the inside surface of substrate 12 and 14, when applying voltage, the twist alignment of nematic liquid crystal is eliminated, and forms according to the mode vertical orientated relative to real estate.Liquid crystal cells LC also can comprise other the parts such as color filter.

About TN pattern liquid crystal cells LC, be not particularly limited, the liquid crystal cells as the formation of TN pattern proposition can use.The Δ nd of the liquid crystal cells of TN pattern is generally 350 ~ 450nm.

The light sources used in backlight BL etc. are not particularly limited.Backlight BL can regulate component such as prismatic lens, the diffusion barrier etc. of the effect of the directive property of light to regulate by configuring have.

Embodiment

Below list embodiment and comparative example is more specifically described feature of the present invention.Material shown in following embodiment, use amount, ratio, contents processing, treatment step etc. only otherwise exceed purport of the present invention, can suitably change.Therefore, scope of the present invention should not by the limited explanation of concrete example shown below.

(making of phase retardation film 1A)

Use cellulose acylate and the adjuvant of the degree of substitution recorded in following table, and then carry out stretch processing under the stretching condition shown in following table, make phase retardation film.

The modulation of particle dispersion liquid

Following composition is uniformly mixed, modulation particle dispersion liquid.

Particulate (Aerosil Co., Ltd. of R972V(Japan system)) 11 mass parts

Ethanol 89 mass parts

The modulation of particulate annex solution

To in the dissolving tank that methylene chloride is housed, add cellulose acylate with following ratio, after heating makes it dissolve completely, use the peace of An Ji filter paper Co., Ltd. to amass filter paper No.244 and it is filtered.While fully stirred by the Cellulose acylate solutions after filtering, add the particle dispersion liquid of above-mentioned modulation wherein lentamente with the ratio recorded in following table.And then, utilize masher to disperse.Its FINEMET NF with Japan Jingxian Co., Ltd is filtered, modulation particulate annex solution.

Methylene chloride 99 mass parts

Cellulose acylate (with reference to following table) 4 mass parts

Particle dispersion liquid 11 mass parts

The modulation of main rubber cement liquid

Modulate the main rubber cement liquid of following composition.First, in dissolved under pressure tank, methylene chloride and ethanol is added.Stir while drop into cellulose acylate in the dissolved under pressure tank that solvent is housed.It is heated, stirs and make it dissolve completely, add further and dissolve the plastifier recorded in following table.Use the peace of An Ji filter paper Co., Ltd. to amass filter paper No.244 to filter it, modulate main rubber cement liquid.

The composition > of the main rubber cement liquid of <

Main rubber cement liquid 100 mass parts and particulate annex solution 2 mass parts line mixer (in Toray Inc. silent oscillation pipe mixer Hi-Mixer, SVII) are fully mixed and modulate rubber cement, use bandcast device, by its equably curtain coating to wide be 2m stainless steel band supporter on.On stainless steel band supporter, make solvent be evaporated to residual solvent amount and reach till 40%, peel off from stainless steel band supporter.Held at tablet both ends with stenter, residual solvent amount when starting is 15 quality %, temperature is stretch 30% along width (TD) direction in the scope of 130 DEG C ~ 140 DEG C stretching.And then conveying carries out drying in 30 minutes in the 3rd arid region being set as 125 DEG C, make wide for 1.5m and end has wide is 1cm, the height cellulose acylate film that is thickness shown in the following table of the annular knurl of 8 μm.Use it as phase retardation film.

(making of phase retardation film 2A)

Use cellulose acylate and the adjuvant of the degree of substitution recorded in following table, and then carry out stretch processing under the stretching condition shown in following table, in addition, operate in the same manner as phase retardation film 1A, made phase retardation film 2A.

Table 2

Phase retardation film	1A	2A
			Ac degree of substitution	1.7	2.0
Pr degree of substitution	0.7	0.5
			Total degree of substitution	2.4	2.5
TD extensibility (%)	30	30
			Design thickness (μm)	40	40
Re（nm）	48	41
			Rth（nm）	120	115

(making of phase retardation film 11)

Use commercially available cyclic polyolefin film ZEONOR ZF14(Co., Ltd. optes system).

(making of diaphragm 1)

Use commercially available cellulose acylate film TF80(Fuji Photo Film Co., Ltd. system).

(making of diaphragm 2)

Cellulose acylate film TF80(Fuji Photo Film Co., Ltd. system by commercially available) at the temperature of 185 DEG C, stretch 20% along TD direction with stenter, the film obtained is used as diaphragm 2.

(MEASURING THE THERMAL EXPANSION COEFFICIENT method)

Use commercially available TMA(thermo-mechanical analysis, Thermo Mechanical Analysis) (electricity Xie Co., Ltd. of science system, TMA8310), the MD(film throughput direction at measuring 40 DEG C ~ 80 DEG C), the TD(direction orthogonal with film throughput direction) deflection.

In the blanket of nitrogen of 100ml/ minute, when the thickness of film is 100 μm, measured by Constant Tensile Load method under the stress of 50mN.Measure the temperature range that temperature is set as 40 DEG C ~ 80 DEG C, programming rate is set as 3 DEG C/min.Thermal expansivity (CTE) is shown below and obtains with the form of the average coefficient of expansion between 40 DEG C ~ 80 DEG C.

CTE={(L80-L40)/(L40×(80-40))}×10 ^-6(ppm/℃)

[in formula, the length of coupons when L80 represents 80 DEG C, the length of coupons when L40 represents 40 DEG C.]

Result is shown in table 3 with the form of C1, C2.

(saponification process)

The phase retardation film 1A made is flooded 3 minutes at 55 DEG C in the sodium hydrate aqueous solution of 1.5 equivalents.

Clean in the washing bath of room temperature, in carrying out with the sulfuric acid of 0.1 equivalent at 30 DEG C and.Again clean in the washing bath of room temperature, and then carry out drying in the warm braw of 100 DEG C.So, by phase retardation film surface saponification.

(making of polaroid 1)

Make the polyvinyl alcohol film absorption iodine of drawn, thus make the polarizer.Then, with polyethenol series bonding agent, the phase retardation film 1A of making is attached to the side of the polarizer.The slow axis of phase retardation film 1A and the axis of homology of the polarizer configure in a parallel manner.

Then, similarly saponification process is carried out to diaphragm 1, use polyethenol series bonding agent, diaphragm 1 is attached to the opposition side of the above-mentioned polarizer.So, polaroid 1 has been made.

(making of polaroid 2)

Replacing phase retardation film 1A except using phase retardation film 2A, using diaphragm 2 to replace except diaphragm 1, and polaroid 1 similarly operates, and has made polaroid 2.

(making of polaroid 11)

Except using phase retardation film 11, and polaroid 1 similarly operates, and has made polaroid 11.

The uneven assay method > of < front contrast

Peel off employing a pair polaroid arranged in the liquid crystal indicator (LL-191A-B, Sharp Co., Ltd. system) of TN type liquid crystal cells, replace, by by above-mentioned making viewable side polaroid according to phase retardation film be liquid crystal cell side mode, be attached to observer side by bonding agent.In addition, by backlight side polaroid according to phase retardation film be liquid crystal cell side mode, be attached to backlight side by bonding agent.The axis of homology of the axis of homology of the polaroid of observer side and the polaroid of backlight side is configured according to the mode becoming E pattern.

Such liquid crystal indicator is respectively made 10, front contrast during commercially available product is set to 100, measure front contrast now and its ratio, 10 middle front contrast are reduced maximum values and records in the form of data.

Table 3

	Embodiment 1	Embodiment 2	Comparative example 1
				Diaphragm	Diaphragm 1	Diaphragm 2	Diaphragm 1
C1 MD（ppm/℃）	58	62	58
				C1 TD（ppm/℃）	56	38	56
C1 MD／C1 TD	1.04	1.63	1.04
				Phase retardation film	Phase retardation film 1A	Phase retardation film 2A	Phase retardation film 11
C2 MD（ppm/℃）	70	65	67
				C2 TD（ppm/℃）	27	33	58
C2 MD／C2 TD	2.59	1.97	1.16
				Polaroid	Polaroid 1	Polaroid 2	Polaroid 11
C1 MD－C2 MD	-12	-3	-9
				C1 TD－C2 TD	29	5	-2
P value	1.55	0.34	0.12
				Q value	-348	-15	18
Crimp values	25mm	9mm	33mm
				Liquid crystal indicator	Liquid crystal indicator 1	Liquid crystal indicator 2	Liquid crystal indicator 11
Front contrast is uneven	96	98	90

MD: film throughput direction

TD: the direction orthogonal with film throughput direction

Can be understood by the result shown in upper table, by the relation making the thermal expansivity of diaphragm and phase retardation film meet regulation, decrease the inequality of front contrast.

Claims (11)

1. a polaroid, it possesses the polarizer, be positioned at the diaphragm of the side of the described polarizer and be positioned at the phase retardation film of opposite side of the described polarizer,

The absorption axle angulation of the long limit of described polaroid or minor face and the described polarizer is 45 degree of directions,

Described phase retardation film is the film using cellulose acylate as principal ingredient,

The feature of described polaroid is, is set to C1 at the thermal expansivity in the MD direction by described diaphragm _mD, the thermal expansivity in TD direction is set to C1 _tD, and the thermal expansivity in the MD direction of described phase retardation film is set to C2 _mD, the thermal expansivity in TD direction is set to C2 _tDtime,

Meet following formula (i) and (ii) simultaneously:

I () is at C2 _mD>=C2 _tDtime, P=|C1 _mD/ C1 _tD-C2 _mD/ C2 _tD|,

At C2 _mD< C2 _tDtime, P=|C1 _tD/ C1 _mD-C2 _tD/ C2 _mD|,

0＜P≤6.0；

(ii)Q＝(C1 _MD－C2 _MD)×(C1 _TD－C2 _TD)＜0。

2. polaroid according to claim 1, wherein, the P in described (i) is 0.1 ~ 1.0.

3. polaroid according to claim 1, wherein, the Q in described (ii) is-5 ~-200.

4. polaroid according to claim 1, wherein, the P in described (i) is 0.1 ~ 1.0, and the Q in described (ii) is-5 ~-200.

5. polaroid according to claim 1, wherein, the C1 in described (i) and (ii) _mD, C1 _tD, C2 _mDand C2 _tDbe respectively 20 ~ 80ppm/ DEG C.

6. polaroid according to claim 1, wherein, the C1 in described (i) _mD/ C1 _tDbe 1.2 ~ 4.0.

7. polaroid according to claim 1, wherein, the C2 in described (i) _mD/ C2 _tDbe 1.8 ~ 4.0.

8. polaroid according to claim 1, wherein, described cellulose acylate is the total degree of substitution of acyl group is the cellulose acylate of 2.2 ~ 2.6.

9. polaroid according to claim 1, wherein, described cellulose acylate is the cellulose acetate propionate meeting following formula (1) and (2),

(1)2.2≤A+B≤2.6

(2)0.3≤B≤1.2

Wherein, A represents the degree of substitution of the acetyl group in cellulose acylate, and B represents the degree of substitution of the propiono in cellulose acylate.

10. polaroid according to claim 4, wherein, the C1 in described (i) _mD/ C1 _tDbe 1.2 ~ 4.0, the C2 in described (i) _mD/ C2 _tDbe 1.8 ~ 4.0, described cellulose acylate is the cellulose acetate propionate meeting following formula (1) and (2),

(1)2.2≤A+B≤2.6

(2)0.3≤B≤1.2

Wherein, A represents the degree of substitution of the acetyl group in cellulose acylate, and B represents the degree of substitution of the propiono in cellulose acylate.

11. 1 kinds of TN mode LCDs, it has the polaroid according to any one of claim 1 ~ 10.