WO2015166971A1

WO2015166971A1 - Phase difference film roll, method for manufacturing same, polarizer, and liquid-crystal display device

Info

Publication number: WO2015166971A1
Application number: PCT/JP2015/062916
Authority: WO
Inventors: 健太間島; 真一郎鈴木
Original assignee: コニカミノルタ株式会社
Priority date: 2014-05-02
Filing date: 2015-04-30
Publication date: 2015-11-05
Also published as: JPWO2015166971A1

Abstract

An objective of the present invention is to provide a phase difference film roll which has a high phase difference and which is capable of suppressing display unevenness arising from deformations in the roll. This phase difference film roll is obtained by rolling a phase difference film in the length direction of the film, which is embossed on both end parts in the width direction. The phase difference film includes a diacetyl cellulose and a retardation increasing agent as primary constituents. At least a portion of the lateral face shapes of both ends of the roll in the axial direction have wave shapes.

Description

Retardation film roll and method for producing the same, polarizing plate and liquid crystal display device

The present invention relates to a roll of retardation film, a method for producing the roll, a polarizing plate, and a liquid crystal display device.

The retardation film is used for the purpose of improving the visibility of liquid crystal display devices and the like. For example, as a retardation film for VA, a film containing triacetyl cellulose and a retardation increasing agent such as a triazine ring compound or a rod-like compound; a film mainly composed of cellulose acetate propionate, and the like are known ( For example, Patent Documents 1 and 2).

In recent years, with the thinning of liquid crystal display devices, the retardation film is also required to be thin. However, when the retardation film is thinned, the retardation value is lowered and it is difficult to obtain a desired retardation value. Therefore, in the case of a film mainly composed of cellulose triacetate film, the addition amount of the retardation increasing agent is increased; in the case of a film mainly composed of cellulose acetate propionate, it is considered to add a retardation increasing agent. Has been.

Japanese Patent No. 4686351 Japanese Patent No. 5319966

By the way, the retardation film is usually wound on both ends of the long film in the width direction; the roll film is wound in the long direction and stored as a roll body. However, a roll body obtained by winding a long retardation film containing triacetyl cellulose or cellulose acetate propionate and a retardation increasing agent by a usual method is deformed during long-term storage. There was a problem that it was easy. Thus, the roll body obtained by winding the thin film retardation film used for VA or the like by a usual method has a problem that it is easily deformed during long-term storage.

The reason why the roll body is deformed during long-term storage is not necessarily clear, but can be considered as follows. That is, the deformation of the roll body is a phenomenon in which the winding diameter at both ends in the width direction of the film where the embossed portions overlap each other is significantly larger than the winding diameter at the central portion in the width direction of the film, and a large wrinkle that bends vertically is generated. Say. When a long retardation film containing triacetyl cellulose or cellulose acetate propionate and a retardation increasing agent is made thinner than before, the content of the retardation increasing agent is increased in order to obtain a desired retardation. It is assumed that the strength of the film is reduced; as a result, deformation of the roll body is likely to occur significantly.

When such a roll body is deformed, non-uniform tension is easily applied to the wound retardation film, and unevenness of the retardation is likely to occur. A retardation film having such retardation unevenness causes display unevenness of a liquid crystal display device.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a roll body of a retardation film that has a high retardation and can suppress display unevenness due to deformation of the roll body.

[1] A roll obtained by winding a retardation film having embossed portions at both ends in the width direction in the longitudinal direction of the film, the retardation film comprising diacetyl cellulose as a main component and retardation A roll body of a retardation film comprising a rising agent, wherein at least a part of a side surface shape of both end portions in the axial direction of the roll body is wavy.
[2] The retardation film roll according to [1], wherein the retardation film has a thickness of 15 to 35 μm.
[3] The retardation film R ₀ defined in the following formula (I) and measured in the in-plane direction at a measurement wavelength of 590 nm is 20 to 130 nm, and is defined by the following formula (II). And a retardation film roll according to [1] or [2], wherein retardation Rth in the thickness direction measured at a measurement wavelength of 590 nm is 100 to 300 nm.
Formula (I) R ₀ = (nx−ny) × t (nm)
Formula (II) Rth = {(nx + ny) / 2−nz} × t (nm)
(In formulas (I) and (II),
nx represents the refractive index in the slow axis direction x where the refractive index is maximum in the in-plane direction of the film; ny represents the refractive index in the direction y perpendicular to the slow axis direction x in the in-plane direction of the film. Nz represents the refractive index in the thickness direction z of the film; t (nm) represents the thickness of the film)
[4] The retardation film roll according to any one of [1] to [3], wherein the content of the retardation increasing agent is 1 to 10 parts by mass with respect to 100 parts by mass of the diacetylcellulose.
[5] The retardation film includes a polymer having a repeating structure derived from a monomer represented by the following general formula (A), a compound represented by the general formula (B), and a compound represented by the general formula (C). And a roll of retardation film according to any one of [1] to [4], further comprising at least one selected from the group consisting of compounds represented by formula (D).

(In general formula (A),
R ¹ and R ² each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;
R ³ represents a substituent;
Ring A represents a 5 or 6 membered ring;
n represents an integer of 1 to 4, and when n is 2 or more, a plurality of R ³ may be the same or different from each other)

(In the general formula (B),
R ¹ represents a hydrogen atom or a substituent;
R ² represents a substituent represented by the following general formula (B-1);
n1 represents an integer of 0 to 4, and when n1 is 2 or more, a plurality of R ¹ may be the same or different from each other;
n2 represents an integer of 1 to 5, and when n2 is 2 or more, a plurality of R ² may be the same or different)

(In the general formula (B-1),
A represents a substituted or unsubstituted aromatic ring;
R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a substituent represented by the general formula (B-2);
R ⁵ represents a single bond or an alkylene group having 1 to 5 carbon atoms;
X represents a substituted or unsubstituted aromatic ring;
n3 represents an integer of 0 to 10, and when n3 is 2 or more, a plurality of R ⁵ and X may be the same or different from each other)

(In the general formula (B-2),
X represents a substituted or unsubstituted aromatic ring;
R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
n5 represents an integer of 1 to 11, and when n5 is 2 or more, a plurality of R ⁶ , R ⁷ , R ⁸ and X may be the same or different)

(In the general formula (C),
R ²⁶ represents an aryl group having 6 to 12 carbon atoms;
R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms;
R ²⁶ and R ²⁷ may each have a substituent)

(In general formula (D),
R represents a substituent;
m and n each independently represents an integer of 1 to 3)
[6] A step of preparing a long retardation film including diacetylcellulose as a main component and a retardation increasing agent and having embossed portions at both ends in the width direction; and winding the retardation film into a core The step of winding the phase difference film and the core while periodically oscillating at least one of the phase difference film and the core in the width direction of the phase difference film. The manufacturing method of the roll body of retardation film including the vibration winding process wound up to the said winding core.
[7] The method for producing a roll of retardation film according to [6], wherein the amplitude of vibration in the vibration winding process is increased as the integrated thickness of the phase difference film to be wound increases.
[8] Manufacture of roll body of retardation film according to [6] or [7], wherein the period of vibration in the vibration winding process is decreased as the integrated thickness of the phase difference film to be wound is increased. Method.

[9] A polarizing plate comprising a polarizer and a retardation film obtained from the roll according to any one of [1] to [5] disposed on at least one surface of the polarizer.
[10] The first polarized light including a liquid crystal cell, a first polarizing plate disposed on one surface of the liquid crystal cell, and a second polarizing plate disposed on the other surface of the liquid crystal cell. The plate is disposed on the surface of the first polarizer, the protective film F1 disposed on the surface of the first polarizer opposite to the liquid crystal cell, and the surface of the first polarizer on the liquid crystal cell side. The second polarizing plate includes a second polarizer, a protective film F3 disposed on a surface of the second polarizer on the liquid crystal cell side, and the second polarizing plate. A protective film F4 disposed on a surface of the polarizer opposite to the liquid crystal cell, and at least one of the protective films F2 and F3 is formed of the roll body according to any one of [1] to [5]. A liquid crystal display device comprising the obtained retardation film.

According to the present invention, it is possible to provide a roll body of a retardation film that has a high retardation and can suppress display unevenness due to deformation of the roll body.

It is a schematic diagram which shows an example of the roll body of the retardation film of this invention. It is a schematic diagram which shows the example of the cross-sectional shape of an embossed part. It is the schematic which shows an example of the winding apparatus used for the winding-up process of retardation film. It is a graph for demonstrating the vibration in a vibration winding process. It is the schematic which shows an example of the simulation result of the integrating | accumulating emboss height in the width direction of the roll body of retardation film. It is a schematic diagram which shows an example of a liquid crystal display device. It is a graph which shows the vibration conditions in the vibration winding process in an Example.

As described above, a roll body obtained by winding a long retardation film containing triacetyl cellulose or cellulose acetate propionate and a retardation increasing agent by a normal method is a roll body during long-term storage. Easy to deform. The reason for this is not clear, but is assumed as follows. That is, when a long retardation film containing triacetyl cellulose or cellulose acetate propionate and a retardation increasing agent is made thinner than before, the content of the retardation increasing agent is obtained in order to obtain a desired retardation. You have to make more. As a result, the orientation state of the cellulose ester molecules is lowered, and the film strength is likely to be lowered;

A roll body obtained by winding such a low-strength retardation film by a usual method is likely to be deformed after long-term storage. Deformation of the roll body is particularly likely to occur particularly when the retardation film is thin and the film strength is lower. When such a roll body is deformed, non-uniform tension is easily applied to the retardation film, and the optical characteristics are likely to vary. Such a retardation film tends to cause display unevenness of a liquid crystal display device.

In contrast, in the present invention, a desired retardation value can be obtained by combining diacetyl cellulose and a retardation increasing agent even if the film thickness is reduced. As a result, since it is not necessary to increase the amount of addition of the retardation increasing agent excessively, a decrease in film strength can be reduced, and deformation of the roll body after long-term storage can be reduced.

Furthermore, the roll of the retardation film is subjected to a vibration winding process in which at least one of the film and the core is vibrated while periodically vibrating in the width direction of the film. Can be suppressed to a higher degree.

That is, the roll body of the retardation film of the present invention is obtained by winding a retardation film containing diacetyl cellulose and a retardation increasing agent through a vibration winding process. The roll body of the retardation film obtained through the vibration winding process includes a portion in which the side surface shape of both end portions in the axial direction is wavy.

1. Retardation Film As described above, the retardation film of the present invention contains diacetyl cellulose as a main component and a retardation increasing agent. “Containing diacetyl cellulose as a main component” means, for example, that the content of diacetyl cellulose in the retardation film is 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more.

<About diacetylcellulose>
Diacetylcellulose is a compound in which part of the hydroxyl groups of cellulose is substituted with acetyl groups. The degree of substitution of acetyl groups in diacetylcellulose is 2.0 or more and less than 2.6, from the viewpoint of obtaining a sufficient phase difference, preferably 2.0 to 2.55, more preferably 2.0 to 2.5. More preferably, it may be 2.0 or more and less than 2.5. In order to enhance the retardation development, it is preferable that the substitution degree of the acetyl group is low.

The degree of substitution of the acetyl group of diacetylcellulose can be measured by the method prescribed in ASTM-D817-96.

The weight average molecular weight of diacetyl cellulose is preferably 5.0 × 10 ⁴ to 5.0 × 10 ⁵ in order to obtain a certain level of mechanical strength, and 1.0 × 10 ⁵ to 3.0 ×. 10 ⁵ is more preferable, and 1.5 × 10 ⁵ to 2.9 × 10 ⁵ is even more preferable. The molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of diacetylcellulose is preferably 1.0 to 4.5.

The weight average molecular weight and molecular weight distribution of diacetylcellulose can be measured by gel permeation chromatography (GPC). The measurement conditions are as follows.
Solvent: Methylene chloride Column: Three Shodex K806, K805, K803G (manufactured by Showa Denko KK) are connected and used.
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 1.0 × 10 ⁶ to 5.0 × 10 ² 13 calibration curves are used. The 13 samples are preferably selected at approximately equal intervals.

<About the retardation increasing agent>
The retardation increasing agent is a compound having a function of increasing the retardation value of the film. The retardation increasing agent is a compound that can make the retardation value Rth (wavelength 590 nm) in the thickness direction 1.1 times or more that of an unadded film in a film added with 3 parts by mass with respect to 100 parts by mass of diacetylcellulose. It is preferable.

Examples of such retardation increasing agents include discotic compounds described in paragraphs 0041 to 0063 of Japanese Patent No. 5311966, paragraphs 0036 to 0124 of Japanese Patent No. 54277738, paragraphs 0164 to 0169 of Japanese Patent No. 4686351, and the like. Examples include nitrogen-containing heterocyclic compounds described in paragraphs 0087 to 0194 of Application No. 2014-010918, rod-like compounds described in paragraphs 0030 to 0158 of Japanese Patent No. 4686351, and the like.

Of these, the retardation increasing agent is preferably a nitrogen-containing heterocyclic compound because it has excellent retardation and good compatibility with diacetylcellulose. Since nitrogen-containing heterocyclic compounds have good compatibility with diacetylcellulose, pyrrole ring, pyrazole ring, imidazole ring, triazole ring (1,2,4-triazole ring or 1,2,3-triazole ring) , A triazine ring, a pyrimidine ring, or a compound containing a pyridine ring, more preferably a compound containing a pyrrole ring, a pyrazole ring, an imidazole ring or a triazole ring.

That is, the retardation increasing agent is preferably a compound represented by any one of the following general formulas (1) to (6).

A in the general formula (1) represents a pyrazole ring.

Ar ₁ and Ar _{2 in} the general formula (1) are each an aryl group or a heteroaryl group; preferably an aryl group. The aryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 10 carbon atoms. Examples of the aryl group include a phenyl group and a naphthyl group. A heteroaryl group is a 5- or 6-membered aromatic heterocyclic group, and examples thereof include a pyrrole ring, a pyrazole ring, an imidazole ring, a 1,2,3-triazole ring, and a 1,2,4-triazole ring. , Tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, isoxadiazole ring, thiophene ring, thiazole ring, isothiazole ring, thiadiazole ring, isothiadiazole ring and the like.

The aryl group and heteroaryl group represented by Ar ₁ or Ar ₂ may further have a substituent. Examples of such substituents include
Halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom);
Alkyl groups (methyl group, ethyl group, n-propyl group, isopropyl group, tert-butyl group, n-octyl group, 2-ethylhexyl group, etc.);
A cycloalkyl group (a cyclohexyl group, a cyclopentyl group, a 4-n-dodecylcyclohexyl group, etc.);
Aryl groups (phenyl, p-tolyl, naphthyl, etc.);
Heteroaryl group (2-pyrrole group, 2-furyl group, 2-thienyl group, pyrrole group, imidazolyl group, oxazolyl group, thiazolyl group, benzoimidazolyl group, benzoxazolyl group, 2-benzothiazolyl group, pyrazolinone group, pyridyl group , Pyridinone group, 2-pyrimidinyl group, triazine group, pyrazole group, 1,2,3-triazole group, 1,2,4-triazole group, oxazole group, isoxazole group, 1,2,4-

oxadiazole group

1,3,4-oxadiazole group, thiazole group, isothiazole group, 1,2,4-thiodiazole group, 1,3,4-thiadiazole group, etc.);
An alkoxy group (methoxy group, ethoxy group, isopropoxy group, tert-butoxy group, n-octyloxy group, 2-methoxyethoxy group, etc.);
Aryloxy groups (phenoxy group, 2-methylphenoxy group, 4-tert-butylphenoxy group, 3-nitrophenoxy group, 2-tetradecanoylaminophenoxy group, etc.);
An acyl group (acetyl group, pivaloyl group, benzoyl group, etc.);
Acyloxy groups (alkylcarbonyloxy groups such as formyloxy group, acetyloxy group, pivaloyloxy group and stearoyloxy group; arylcarbonyloxy groups such as benzoyloxy group and p-methoxyphenylcarbonyloxy group);
An amino group (amino group, methylamino group, dimethylamino group, anilino group, N-methyl-anilino group, diphenylamino group, etc.);
A cyano group, a hydroxy group, a nitro group, a carboxy group and the like are included. Of these, a heteroaryl group (preferably a pyrazole group) and an acyloxy group (preferably an arylcarbonyloxy group) are preferable. These substituents may further have other substituents.

R _{1 in the} general formula (1) represents a hydrogen atom, an alkyl group, an aryl group, an acyl group, a sulfonyl group, an alkyloxycarbonyl group or an aryloxycarbonyl group; preferably a hydrogen atom or an alkyl group.

The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a tert-butyl group, an n-octyl group, and a 2-ethylhexyl group. Etc. are included. The aryl group is preferably an aryl group having 6 to 20 carbon atoms, and examples thereof include a phenyl group. The acyl group is preferably an acyl group having 2 to 20 carbon atoms, and examples thereof include an acetyl group and a pivaloylbenzoyl group. The sulfonyl group is preferably an alkylsulfonyl group having 1 to 10 carbon atoms, and examples thereof include a methylsulfonyl group and an ethylsulfonyl group. The alkyloxycarbonyl group is preferably an alkyloxycarbonyl group having 2 to 10 carbon atoms, and examples thereof include a methoxycarbonyl group. The aryloxycarbonyl group is preferably an aryloxycarbonyl group having 7 to 20 carbon atoms, and examples thereof include a phenoxycarbonyl group.

Q in the general formula (1) represents an integer of 1 to 2; n and m each independently represents an integer of 1 to 3;

Specific examples of the compound represented by the general formula (1) include the following compounds.

X ¹ to X ^{3 in} the general formula (2) are each independently a single bond, —NR ⁴ —, —O— or —S—; preferably —NR ⁴ —. Each R ^{4 in} —NR ⁴ — is independently a hydrogen atom, an alkyl group, an alkenyl group, an aryl group or a heteroaryl group, preferably a hydrogen atom.

The number of carbon atoms of the alkyl group represented by R ⁴ can be preferably 1 to 10, more preferably 1 to 6. The carbon number of the alkenyl group is preferably 2 to 10, more preferably 2 to 6. The aryl group may preferably have 6 to 20 carbon atoms. The carbon number of the heteroaryl group is preferably 5 to 23, and more preferably 5 to 17. These groups may further have a substituent, and examples thereof include a halogen atom, an alkoxy group (for example, methoxy group, ethoxy group) and an acyloxy group (for example, acryloyloxy group, methacryloyloxy group). It is.

R ¹ to R ^{3 in} the general formula (2) are each independently an alkyl group, an alkenyl group, an aryl group or a heteroaryl group, preferably an aryl group or a heteroaryl group, and more preferably an aryl group.

The number of carbon atoms of the aryl group represented by R ¹ to R ³ can be preferably 6 to 20. Examples of the aryl group include a phenyl group and a naphthyl group. The heterocycle constituting the heteroaryl group is preferably a 5-membered or 6-membered unsaturated heterocycle. The hetero atom of the heterocyclic ring is a nitrogen atom, a sulfur atom or an oxygen atom, preferably a nitrogen atom. Examples of heteroaryl groups include 2-pyridyl or 4-pyridyl.

The aryl group or heteroaryl group may further have a substituent. Examples of such substituents include a halogen atom, a nitro group, a cyano group, an alkyl group (preferably an alkyl group having 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms), an alkoxy group (preferably having a carbon number). 1 to 12, more preferably 1 to 4 alkoxy groups).

Examples of the compound represented by the general formula (2) include the following.

Ra in the general formula (3) represents an alkyl group, an alkenyl group, an alkynyl group, a heteroaryl group or an aryl group; preferably an alkyl group or an aryl group. The number of carbon atoms of the alkyl group is preferably 1-20, more preferably 3-15, and even more preferably 6-12. The alkynyl group preferably has 2 to 20 carbon atoms, more preferably 3 to 15 carbon atoms, and still more preferably 6 to 12 carbon atoms. The number of carbon atoms of the aryl group is preferably 6 to 24, more preferably 6 to 18. The carbon number of the heteroaryl group is preferably 5 to 23, more preferably 5 to 17.

X ¹ to X ^{4 in} the general formula (3) each independently represents a single bond or a divalent linking group; preferably a single bond, more preferably all a single bond. Examples of the divalent linking group include a divalent linking group represented by the following general formula (Q) and an alkylene group (preferably having 1 to 30 carbon atoms, more preferably 1 to 3 carbon atoms, and still more preferably carbon atoms. An alkylene group having a number of 2), an arylene group (preferably an arylene group having 6 to 30 carbon atoms, more preferably an arylene group having 6 to 10 carbon atoms), and the like, preferably a divalent group represented by the following general formula (Q): A linking group, more preferably a carbonyl group. * Of general formula (Q) is a connection part with the N atom substituted on the heterocyclic ring of general formula (3).

R ¹ to R ^{4 in} the general formula (3) each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group; preferably a hydrogen atom, an alkyl group, an aryl group or a heteroaryl group More preferably a hydrogen atom or an alkyl group. At least one of R ¹ and R ² and at least one of R ³ and R ⁴ are preferably hydrogen atoms.

The number of carbon atoms of the alkyl group represented by R ¹ to R ⁴ is preferably 1 to 12, more preferably 1 to 6, and still more preferably 1 to 4. The alkenyl group and alkynyl group each preferably have 2 to 12 carbon atoms, more preferably 2 to 6 carbon atoms, and still more preferably 2 to 4 carbon atoms. The aryl group preferably has 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms, and still more preferably 6. These groups may further have a substituent.

Examples of the compound represented by the general formula (3) include the following.

Y ^{1 in the} general formula (4) represents a methine group or —N—; preferably —N—.

Q ^{21 in the} general formula (4) represents a single bond, —O—, —S—, or —NRf—. Rf in —NRf— represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heteroaryl group, and may be linked to Ra ³¹ to form a ring.

Ra ^{31 in the} general formula (4) represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group. The alkyl group, alkenyl group, alkynyl group, aryl group or heteroaryl group represented by Ra ³¹ is the alkyl group, alkenyl group, alkynyl group, aryl group or heteroaryl represented by Ra in the general formula (3). Synonymous with group.

X ³² and X ^{33 in} formula (4) each independently represent a single bond or a divalent linking group; preferably a single bond. The divalent linking group may have the same meaning as the divalent linking group in X ¹ to X ⁴ of the general formula (3). X ³¹ and X ³⁴ are divalent linking groups represented by the aforementioned general formula (Q); preferably a carbonyl group.

Rb ³¹ to Re ^{31 in} the general formula (4) each independently represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group. The alkyl group, alkenyl group, alkynyl group, aryl group or heteroaryl group represented by Rb ³¹ to Re ³¹ is the alkyl group, alkenyl group or alkynyl represented by R ¹ to R ⁴ in the general formula (3). Each having the same meaning as a group, an aryl group or a heteroaryl group.

Examples of the compound represented by the general formula (4) include the following.

Q ³¹ and Q ^{32 in} the general formula (5) each independently represent —O—, —S—, or —NRf—. Rf in —NRf— represents a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group, and may be linked to Ra ⁴¹ to form a ring.

Ra ⁴¹ and Rg ^{41 in} the general formula (5) represent an alkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heteroaryl group. The alkyl group, alkenyl group, alkynyl group, aryl group or heteroaryl group represented by Ra ⁴¹ and Rg ⁴¹ is the alkyl group, alkenyl group, alkynyl group, aryl group represented by Ra in the general formula (3). Or it is synonymous with heteroaryl group, respectively.

X ^{43 in} formula (5) represents a single bond or a divalent linking group; preferably a single bond. The divalent linking group may have the same meaning as the divalent linking group in X ¹ to X ⁴ of the general formula (3). X ⁴⁴ represents a divalent linking group represented by the aforementioned general formula (Q); preferably a carbonyl group.

Rd ⁴¹ and Re ^{41 in} the general formula (5) each independently represent a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heteroaryl group. The alkyl group, alkenyl group, alkynyl group, aryl group or heteroaryl group represented by Rd ⁴¹ and Re ⁴¹ is the alkyl group, alkenyl group, alkynyl represented by R ¹ to R ⁴ in the general formula (3). Each having the same meaning as a group, an aryl group or a heteroaryl group.

Examples of the compound represented by the general formula (5) include the following.

X in the general formula (6) is a group represented by the following general formula (6-1) or general formula (6-2). R ¹ to R ^{8 in} the general formula (6-1) and R ¹¹ to R ^{18 in} the general formula (6-2) each independently represent a hydrogen atom or a substituent. Examples of the substituent include a halogen atom and an alkyl group.

L ¹ and L ^{2 in} the general formula (6) each independently represent —C (═O) O— or —C (═O) NR—. R in —C (═O) NR— represents a hydrogen atom or an alkyl group; preferably a hydrogen atom or a methyl group; more preferably a hydrogen atom. The alkyl group represented by R preferably has 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms.

Ar ¹ and Ar ^{2 in} formula (6) each independently represent an aryl group or a heteroaryl group; preferably an aryl group. The number of carbon atoms of the aryl group represented by Ar ¹ or Ar ² is preferably 6-20, more preferably 6-12. Examples of the aryl group include a phenyl group, a p-methylphenyl group, a naphthyl group, and the like, and preferably a phenyl group.

The heteroaryl group represented by Ar ¹ or Ar ² is a 5- or 6-membered aromatic heterocyclic group containing one or more of an oxygen atom, a nitrogen atom and a sulfur atom. Examples of heteroaryl groups include benzimidazole, benzoxazole, benzthiazole, benzotriazole and the like. Each of the aryl group and the heteroaryl group may further have the aforementioned substituent.

The compound represented by the general formula (6) is preferably represented by the following formula.

R ¹¹¹ to R ^{120 in the} above formula each independently represents a hydrogen atom or a substituent. The substituent is an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group), an alkoxy group (preferably 1 to 12 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms), amino A group or a hydroxyl group, preferably an alkoxy group.

Specific examples of the compound represented by the general formula (6) include the following.

Especially, since compatibility with diacetylcellulose is good and it has high retardation development, the compound represented by general formula (1), the compound represented by general formula (2), and general formula ( Compounds represented by 3) are preferred; compounds represented by general formula (2) and general formula (3) are particularly preferred.

The content of the retardation increasing agent is preferably 1 to 10 parts by mass, more preferably 1 to 7 parts by mass, and further preferably 1 to 5 parts by mass with respect to 100 parts by mass of diacetylcellulose. preferable. When the content of the retardation increasing agent is a certain level or more, the retardation of the film can be sufficiently increased. When the content of the retardation increasing agent is below a certain level, not only the precipitation of the retardation increasing agent can be highly suppressed, but also an excessive decrease in film strength can be suppressed.

<Polarizer degradation inhibitor>
Examples of the polarizer deterioration inhibitor include paragraphs 0057 to 0120 of JP2013-174661, paragraphs 0062 to 0158 of JP2013-174451, paragraphs 0015 to 0031 of JP2013-82918, and JP2013. The compounds described in paragraphs 0047 to 0060 of 97170 are included.

Among them, a polymer containing a repeating unit derived from a monomer represented by the general formula (A) and a compound selected from the group consisting of compounds represented by the general formulas (B) to (D) are used for suppressing deterioration of a polarizer. It can function preferably as an agent.

That is, in the polarizer, the PVA polymer and the dichroic dye form a stabilizing complex by boric acid crosslinking. When moisture enters the polarizer, not only is the boric acid bridge broken, but boric acid is dissipated and the polarizer tends to deteriorate. The polymer containing the repeating unit derived from the monomer represented by the general formula (A) and the compound represented by the general formula (B) have an aromatic ring and have a rigid structure. The film can have a high density. As a result, not only can the moisture transmission amount of the retardation film be reduced, but also the number of diffusion paths of boric acid from the polarizer can be reduced, and deterioration of the polarizer can be suppressed.

The compounds represented by the general formulas (C) and (D) are organic acids having a relatively low water solubility, and can lower the pH in the polarizer. Thereby, destruction of the boric acid bridge | crosslinking in a polarizer can be suppressed, suppressing the acid hydrolysis of the diacetyl cellulose of a phase difference film.

Ring A in general formula (A) represents a 5- or 6-membered ring.

R ¹ and R ^{2 in} formula (A) each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ³ represents a substituent. Examples of the substituent include an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a cyclohexane having 4 to 10 carbon atoms. An alkyl group, an aryl group having 6 to 20 carbon atoms, and the like are included, and an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a phenyl group, and the like are preferably included. n represents an integer of 1 to 4, and when n is 2 or more, the plurality of R ³ may be the same or different from each other.

The monomer represented by the general formula (A) is preferably represented by the following general formula (A-1).

^{A 1} in the general formula (A-1), ^-CR 4 ^{R 5} - represents an or oxygen atom. R ⁴ and R ⁵ in —CR ⁴ R ⁵ — each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ^R ^1, R 2, ^{R 3} and n in the general formula (A-1) is ^R 1 in the general formula ^(A), R 2, respectively ^{R 3} and n synonymous.

The polymer containing a repeating unit derived from the monomer represented by the general formula (A) may further include a repeating structure derived from another monomer. Examples of other monomers include styrene and the like. The content of the repeating unit derived from the monomer represented by the general formula (A) can be about 30 to 99 mol%. The monomer represented by the general formula (A) may be one type or two or more types.

The polymer containing a repeating unit derived from the monomer represented by the general formula (A) may preferably be a copolymer represented by the following general formula (a).

R ²¹ , R ²² and R ²⁴ in the general formula (a) are each independently synonymous with R ^{3 in} the general formula (A). R ²³ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. x, y and z represent molar ratios with respect to all repeating units contained in the polymer, x represents 1 to 40%, y represents 5 to 95%, and z represents 1 to 70%. m1 and m2 each independently represents an integer of 0 to 4. m3 represents an integer of 0-2. m4 represents an integer of 0 to 5. R ¹⁰¹ , R ¹⁰² and R ¹⁰³ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably a hydrogen atom.

Examples of the compound represented by the general formula (A) include Coumarone resin (Nit resin Coumarone G-90, G-100N, V-120S, H-100) manufactured by Nikkaku Chemical Co., Ltd.

The weight average molecular weight of the polymer containing the repeating unit derived from the monomer represented by formula (A) is preferably 200 to 10,000, more preferably 300 to 8,000, and more preferably 400 to 4000. Further preferred. When the weight average molecular weight is not less than a certain value, the density of the retardation film can be improved satisfactorily. Thereby, the diffusion of boric acid from the polarizer can be suppressed, and the polarizer deterioration can be suppressed. When the weight average molecular weight is below a certain level, the compatibility with diacetylcellulose is hardly impaired.

R ^{1 in the} general formula (B) represents a hydrogen atom or a substituent. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 26 carbon atoms, and a hydroxyl group. n1 represents an integer of 0 to 4, and when n1 is 2 or more, the plurality of R ¹ may be the same or different from each other.

R ² in the general formula (B) represents a substituent represented by the following general formula (B-1). n2 represents an integer of 1 to 5, when n2 is 2 or more, plural R ² may being the same or different.

A in the general formula (B-1) represents a substituted or unsubstituted aromatic ring. The aromatic ring is preferably a benzene ring. R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a group represented by General Formula (B-2). R ⁵ represents a single bond or an alkylene group having 1 to 5 carbon atoms. X represents a substituted or unsubstituted aromatic ring. The aromatic ring is preferably a benzene ring. n3 represents an integer of 0 to 10, and when n3 is 2 or more, the plurality of R ⁵ and X may be the same or different from each other.

X in the general formula (B-2) represents a substituted or unsubstituted aromatic ring. The aromatic ring is preferably a benzene ring. R ⁶ to R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. n5 represents an integer of 1 to 11, and when n5 is 2 or more, the plurality of R ⁶ to R ⁹ and X may be the same as or different from each other.

Specific examples of the compound represented by the general formula (B) include the following.

The content of the polymer containing the monomer unit represented by the general formula (A) and the compound represented by the general formula (B) is 0.1 to 15 parts by mass, preferably 0 to 100 parts by mass of diacetylcellulose. .5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass. If content of the said compound is more than fixed, the density of a retardation film can fully be raised and it will be easy to fully suppress deterioration of a polarizer. It can suppress that film strength falls too much that content of the said compound is below fixed.

R ^{26 in the} general formula (C) represents an alkyl group (including a cycloalkyl group) or an aryl group. The alkyl group is preferably an alkyl group having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and may be a methyl group, an ethyl group, a cyclohexyl group, or the like. The aryl group is preferably an aryl group having 6 to 12 carbon atoms, and more preferably a phenyl group.

R ²⁷ and R ^{28 in} formula (C) each independently represent a hydrogen atom, an alkyl group, or an aryl group. The alkyl group and the aryl group can be defined similarly to the above-described alkyl group and aryl group, respectively.

R ²⁶ , R ²⁷ and R ²⁸ may each have a substituent. Examples of the substituent of the aryl group represented by R ²⁶ , R ²⁷ and R ²⁸ include a halogen atom or an alkyl group having 1 to 6 carbon atoms. Examples of the substituent that the alkyl group represented by R ²⁶ , R ^27, and R ²⁸ have include an aryl group having 6 to 12 carbon atoms.

Specific examples of the compound represented by the general formula (C) include the following.

The weight average molecular weight of the compound represented by the general formula (C) is preferably 200 to 1000, and more preferably 250 to 800.

R in the general formula (D) represents a substituent. Examples of the substituent include a substituent represented by the following general formula (D-1). m and n each independently represents an integer of 1 to 3.

Y in the general formula (D-1) represents an oxygen atom or a sulfur atom; preferably an oxygen atom.

R ¹ and R ^{2 in} formula (D-1) each independently represent a hydrogen atom or a substituent. Examples of substituents include alkyl groups, alkenyl groups, aryl groups, heterocyclic groups, alkoxy groups, aryloxy groups, alkoxycarbonyl groups, amino groups, acylamino groups, cyano groups and halogen atoms; preferably alkyl groups , An alkenyl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group or a cyano group; more preferably a hydrogen atom, an aromatic group or an alkyl group; particularly preferably a hydrogen atom or a phenyl group is there. The aromatic group may further have a substituent such as an alkyl group; the alkyl group may further have a substituent such as an aromatic group.

P in formula (D-1) represents an integer of 1 to 3; preferably 1 to 2; more preferably 1.

Specific examples of the general formula (D) include the following.

The content of the compounds represented by the general formulas (C) and (D) is 0.1 to 15 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 0.1 to 100 parts by mass of diacetylcellulose. It may be 5 to 5 parts by mass. If content of the said compound is more than fixed, the inside of a polarizer can be adjusted to low pH, suppressing the acid hydrolysis of the diacetyl cellulose in retardation film, and deterioration of a polarizer can be suppressed preferably. If content of the said compound is below fixed, the excessive fall of film strength can be suppressed.

The retardation film of the present invention may further contain various additives such as a plasticizer, an ultraviolet absorber, and a matting agent (fine particles) as necessary.

<About plasticizer>
Examples of the plasticizer include sugar derivatives and phosphate ester compounds.

The sugar derivative may be a compound in which at least a part of the hydrogen atoms of the hydroxyl group of the sugar is substituted with a substituent. The sugar constituting the sugar derivative preferably has a structure in which 1 to 12 of one or both of the furanose structure and the pyranose structure are bonded; one to both of the furanose structure and the pyranose structure is 1 to 3, preferably 2 It preferably has a bonded structure. Especially, what contains both a pyranose structure and a furanose structure is preferable.

Examples of sugars constituting sugar derivatives include monosaccharides such as glucose, galactose, mannose, fructose, xylose and arabinose; disaccharides such as lactose, sucrose, maltitol, cellobiose and maltose; trisaccharides such as cellotriose and raffinose The structure derived from is included.

The substituent constituting the sugar derivative is an alkyl group (preferably an alkyl group having 1 to 22 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as a methyl group, an ethyl group, a propyl group). Group, hydroxyethyl group, hydroxypropyl group, 2-cyanoethyl group, benzyl group, etc.); aryl group (preferably an aryl group having 6 to 24 carbon atoms, more preferably 6 to 18 carbon atoms, particularly preferably 6 to 12 carbon atoms, for example, Phenyl group, naphthyl group); acyl group (preferably having 1 to 22 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, for example, acetyl group, propionyl group, butyryl group, pentanoyl group) Group, hexanoyl group, octanoyl group, benzoyl group, toluyl group, phthalyl group, naphthal group, and the like. A Le group.

In a sugar derivative, an unreacted hydroxyl group that is not substituted with a substituent may generally remain as it is as a hydroxyl group.

The sugar derivative can be a mixture of a plurality of sugar derivatives having different degrees of substitution. Such a mixture may contain an unsubstituted form. The average substitution rate in the mixture is preferably 62 to 94%. The average substitution rate can be defined by the following formula.
[Equation 1]
Average substitution rate = 100% × (content of each sugar derivative in the mixture) × (number of substituted OH in each molecule of each sugar derivative in the mixture) / (total number of OH in one molecule of unsubstituted sugar) )

Specific examples of the sugar derivative include the following.

Examples of the phosphoric acid ester compound include triphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, and tributyl phosphate.

The content of the plasticizer can be 1 to 40 parts by mass with respect to 100 parts by mass of diacetylcellulose.

<About matting agent>
The matting agent can impart further slipperiness to the retardation film. The matting agent may be fine particles made of an inorganic compound or an organic compound having heat resistance in the film forming process without impairing the transparency of the resulting film.

Examples of inorganic compounds constituting the matting agent include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, and hydrated calcium silicate. , Aluminum silicate, magnesium silicate and calcium phosphate. Of these, silicon dioxide and zirconium oxide are preferable, and silicon dioxide is more preferable in order to reduce an increase in haze of the obtained film.

Specific examples of silicon dioxide include Aerosil 200V, Aerosil R972V, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600, NAX50 (above, Nippon Aerosil Co., Ltd.), Sea Hoster KEP-10, Sea Hoster KEP -30, Seahoster KEP-50 (manufactured by Nippon Shokubai Co., Ltd.), Silo Hovic 100 (manufactured by Fuji Silysia), nip seal E220A (manufactured by Nippon Silica Kogyo), Admafine SO (manufactured by Admatechs) and the like.

The particle shape of the matting agent is indefinite, needle-like, flat or spherical, and may preferably be spherical in view of easy transparency of the resulting film.

The matting agent may be used alone or in combination of two or more. Further, by using particles having different particle diameters and shapes (for example, needle shape and spherical shape, for example), both transparency and slipperiness may be made highly compatible.

When the size of the matting agent particles is close to the wavelength of visible light, the light is scattered and the transparency is lowered. Therefore, the size of the particles of the matting agent is preferably smaller than the wavelength of visible light. / 2 or less is preferable. However, if the size of the particles is too small, the effect of improving slipperiness may not be manifested. Therefore, the size of the particles is preferably in the range of 80 to 180 nm. The particle size means the size of an aggregate when the particle is an aggregate of primary particles. When the particles are not spherical, the size of the particles means the diameter of a circle corresponding to the projected area.

The content of the matting agent can be about 0.05 to 1.0% by mass, preferably 0.1 to 0.8% by mass with respect to diacetylcellulose.

<Physical properties of retardation film>
(Thickness)
The thickness of the retardation film is about 15 to 40 μm, preferably 15 to 35 μm, more preferably 20 to 30 μm in order to make the polarizing plate thinner. If the thickness of the retardation film is preferably 35 μm or less, the roll body tends to be easily deformed, and therefore the present invention is particularly effective. If the thickness of the retardation film is less than 15 μm, the film is likely to be broken and may not be stably produced. From the viewpoint of reducing the thickness of the display device, the retardation film is preferably thinner.

(Retardation)
The retardation of the retardation film can be set according to the type of liquid crystal cell to be combined. The in-plane retardation R ₀ (590) measured at a wavelength of 590 nm under 23 ° C. and RH 55% of the retardation film is preferably 20 to 130 nm, more preferably 30 to 100 nm. The retardation Rth (590) in the thickness direction is preferably 100 to 300 nm, and more preferably 100 to 200 nm. A retardation film having a retardation in the above range is suitable as a retardation film such as a VA liquid crystal cell.

Retardations _R0 and Rth are defined by the following equations, respectively.
Formula (I): R ₀ = (nx−ny) × d (nm)
Formula (II): Rth = {(nx + ny) / 2−nz} × d (nm)
(In formulas (I) and (II),
nx represents the refractive index in the slow axis direction x where the refractive index is maximum in the in-plane direction of the film; ny represents the refractive index in the direction y perpendicular to the slow axis direction x in the in-plane direction of the film. Nz represents the refractive index in the thickness direction z of the film; d (nm) represents the thickness of the film)

The retardations _R0 and Rth can be determined by the following method, for example.
1) The retardation film is conditioned at 23 ° C. and 55% RH. The average refractive index of the retardation film after humidity adjustment is measured with an Abbe refractometer or the like.
The retardation film after 2) humidity, measuring the _{R 0} when the light is incident in parallel to the measurement wavelength 590nm to normal of the film surface, KOBRA21ADH, in Oji Scientific Corporation.
3) With KOBRA21ADH, the slow axis in the plane of the retardation film is the tilt axis (rotation axis), and the measurement wavelength is 590 nm from the angle of θ (incident angle (θ)) with respect to the normal of the surface of the retardation film The retardation value R (θ) when light is incident is measured. The retardation value R (θ) can be measured at 6 points every 10 °, with θ ranging from 0 ° to 50 °. The in-plane slow axis of the retardation film can be confirmed by KOBRA21ADH.
4) nx, ny, and nz are calculated by KOBRA21ADH from the measured R ₀ and R (θ) and the above-described average refractive index and film thickness, and Rth at a measurement wavelength of 590 nm is calculated. The measurement of retardation can be performed under conditions of 23 ° C. and 55% RH.

The total retardation of the retardation film is preferably 80% or more, more preferably 90% or more, and further preferably 93% or more.

The haze value of the retardation film is preferably 3.0% or less, preferably 2.0% or less, more preferably 1.0% or less, and 0.5% or less. Is more preferable. The haze can be measured with a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K-7136.

2. Roll body of retardation film The roll body of the retardation film of the present invention is obtained by winding the above-described retardation film in the longitudinal direction.

FIG. 1 is a schematic view showing an example of a roll body of the retardation film of the present invention. FIG. 1A is a view showing an example of the appearance of a roll body; FIG. 1B is a partial cross-sectional view (cross-sectional view taken along the line AA) along the axial direction of FIG. As shown in FIG. 1 (a), a roll body 10 of a retardation film is a long retardation film wound around a core 11 and embossed portions 13A at both ends in the width direction. 13 and so on.

The roll body of the retardation film of the present invention is obtained through a vibration winding process in which at least one of the film or the core is vibrated in the width direction of the film and the film is wound. Therefore, the roll body 10 obtained includes portions that are laminated so that the embossed portions 13A after winding do not completely overlap each other. That is, the side surface shape of the axial direction both ends of the roll body 10 includes a wavy portion. Specifically, the side surface shape of both end portions in the axial direction of the roll body 10 is wavy, as shown in FIG. 1B. Specifically, both end portions in the axial direction of the cross section along the axial direction of the roll body. The shape is wavy.

When combined with the vibration winding process and the non-vibration winding process, the side surfaces of both ends in the axial direction of the roll body 10 corresponding to the vibration winding process are wavy; The side surface shape of both end portions in the axial direction of the roll body 10 of the portion to be performed is a planar shape.

The embossed portion 13A is provided at both ends in the width direction of the retardation film 13. The width W of the embossed portion 13A can be, for example, 0.2 to 6%, preferably 0.3 to 2% with respect to the total width of the retardation film 13. Specifically, it may be about 0.5 to 30 mm, preferably 5 to 30 mm, more preferably 6 to 20 mm. If the width of the embossed portion 13A is too small, the transportability of the retardation film 13 may not be sufficiently improved, or winding deviation may not be sufficiently suppressed. On the other hand, if the width of the embossed portion 13A is too large, the ratio that can be used as a retardation film tends to decrease.

The height of the convex portion constituting the embossed portion 13A can be about 5 to 60% of the film thickness of the retardation film 13. Specifically, the height of the convex portion constituting the embossed portion 13A is preferably 1.0 to 10.0 μm, more preferably 1.0 to 6.0 μm. The height of a convex part means the height from the film surface in which embossing is not formed to the vertex of a convex part. If the height of the embossed portion 13A is too low, there is a possibility that winding deviation in the roll body cannot be sufficiently suppressed. If the embossed portion 13A is too high, the region where the embossed portions overlap in the roll body tends to be thicker than the other regions. Therefore, even if the above-described vibration winding process is performed, deformation of the roll body may not be sufficiently suppressed.

FIG. 2 is a schematic diagram showing an example of a cross-sectional shape of the embossed portion 13A. Examples of the cross-sectional shape of the embossed portion 13A include a rectangular shape (FIG. 2 (a)); a shape in which a concave portion a is formed in the central portion in the width direction of the embossed portion 13A lower than both end portions in the width direction (FIG. )); Includes a plurality of convex portions b and c, and the convex portion b in the central portion in the width direction of the embossed portion is lower than the convex portions c at both end portions in the width direction (FIG. 2C). . Thus, the overlap of the width direction center part of an embossed part can be made small by making the width direction center part of an embossed part low. Thereby, it is thought that the increase in the thickness of the embossed portion of the roll body can be reduced, and the deformation of the roll body can be further suppressed.

The width of the retardation film 13 can be, for example, 1000 to 6000 mm, preferably 1400 to 4000 mm. The winding length of the retardation film 13 can be set to 100 to 10,000 m, for example.

3. Method for producing retardation film roll body The retardation film roll body of the present invention comprises: 1) a step of preparing a long retardation film having embossed portions at both ends in the width direction; and 2) a retardation film. A winding step. And 2) the step of winding the retardation film is a step of winding the retardation film around the core while vibrating at least one of the retardation film and the core in the width direction of the film (vibration winding). Step).

<About the process of preparing a long retardation film>
The long retardation film is produced by a solution casting method (cast) or a melt casting method (melt); preferably, by a solution casting method (cast) in order to reduce streak failure. Can be done.

A method for producing a long retardation film by a solution casting method (cast) includes: 1-1) a step of obtaining a dope containing diacetyl cellulose as described above; 1-2) casting the dope on a support; Thereafter, a step of drying to obtain a film-like material, 1-3) a step of peeling the film-like material from the support, and 1-5) forming embossed portions at both ends in the width direction of the peeled film-like material And 1-4) may be further included between the 1-3) and the 1-5) as necessary.

1-1) Dissolution Step The organic solvent used for preparing the dope solution can be used without limitation as long as it sufficiently dissolves each of the above components such as diacetylcellulose. Examples of the chlorinated organic solvent include methylene chloride. Examples of the non-chlorine organic solvent include methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate and the like. Of these, methylene chloride is preferred.

The dope preferably further contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in addition to the organic solvent. By containing the aliphatic alcohol, the film-like material is gelled, and peeling from the metal support becomes easy. Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol and the like. Of these, methanol and ethanol are preferable because the stability of the dope, the boiling point is relatively low, and the drying property is good.

Dissolution of diacetylcellulose and the like includes a method performed at normal pressure, a method performed at a temperature lower than the boiling point of the main solvent, a method performed at a pressure higher than the boiling point of the main solvent, and a method performed at a pressure higher than the boiling point of the main solvent. Is preferred.

1-2) Casting step The dope solution is fed to a pressure die through a liquid feed pump (for example, a pressurized metering gear pump). Then, the dope solution is cast from the slit of the pressure die to a casting position on an endless metal support (for example, a stainless belt or a rotating metal drum) that is transferred infinitely.

1-3) Solvent evaporation / peeling step The dope solution cast on the metal support is heated on the metal support to evaporate the solvent in the dope solution to obtain a film-like material.

In order to evaporate the solvent, there are a method of blowing wind from the dope liquid surface side, a method of transferring heat from the back surface of the support by a liquid, a method of transferring heat from the front and back by radiant heat, etc. The drying efficiency is good and preferable. In particular, when a film is formed using a stainless steel belt, the dope solution on the metal support is preferably dried in an atmosphere within a range of 40 to 100 ° C. In order to maintain the atmosphere within the range of 40 to 100 ° C., it is preferable to apply hot air at this temperature to the dope liquid surface on the metal support or to heat by means such as infrared rays. In the case of forming a film using a metal drum, it is preferable that the surface temperature of the metal drum is set to −20 to 10 ° C. and the film is peeled off without being dried on the metal drum.

The film-like material obtained on the metal support is peeled off at the peeling position. When the film is formed using a stainless steel belt, the temperature of the metal support at the peeling position is preferably in the range of 10 to 40 ° C, more preferably in the range of 11 to 30 ° C. When forming a film using a metal drum, the temperature of the metal support at the peeling position is preferably in the range of −20 to 10 ° C.

The residual solvent amount of the film-like material on the metal support at the time of peeling can be, for example, in the range of 50 to 120% by mass. The amount of residual solvent in the film-like material is defined by the following formula.
Residual solvent amount (%) = (mass before heat treatment of film-like material−mass after heat treatment of film-like material) / (mass after heat treatment of film-like material) × 100
The heat treatment for measuring the residual solvent amount represents performing a heat treatment at 140 ° C. for 1 hour.

The peeling tension when peeling the metal support from the film is usually in the range of 196 to 245 N / m. However, if wrinkles easily occur during peeling, peeling with a tension of 190 N / m or less is preferable. Further, it is more preferable to peel with a tension of 80 N / m or less.

1-4) Drying / stretching process The peeled film-like material is dried while being conveyed in the tenter stretching apparatus, or is dried while being conveyed by a plurality of rollers disposed in the drying apparatus. The drying method is not particularly limited, but a method of blowing hot air on both surfaces of the film-like material is common.

Since rapid drying tends to impair the flatness of the resulting film, drying at a high temperature is preferably performed under conditions where the residual solvent is 8% by mass or less. Throughout the drying process, the drying temperature is preferably in the range of 40-190 ° C, more preferably in the range of 40-170 ° C.

The film obtained after drying may be further stretched as necessary. The stretching of the film is preferably performed in at least one of the width direction (TD direction), the transport direction (MD direction) or the oblique direction of the film; more preferably in the width direction (TD direction). When stretching in both the width direction (TD direction) and the transport direction (MD direction) of the film, stretching in the width direction (TD direction) of the film and stretching in the transport direction (MD direction) may be performed sequentially. You may do it simultaneously.

The draw ratio may be about 1.01 to 1.5 times, preferably about 1.01 to 1.3 times in each direction.

When stretching with a tenter stretching apparatus, the residual solvent amount of the film-like material at the start of tenter stretching is preferably 2 to 30% by mass. Furthermore, it is preferable to dry until the amount of residual solvent in the film-like material is 10% by mass or less, preferably 5% by mass or less. The drying temperature is preferably in the range of 30 to 160 ° C, more preferably in the range of 50 to 150 ° C. The tenter method includes a clip tenter and a pin tenter. In the present invention, a pin tenter is preferable from the viewpoint of productivity.

1-5) Emboss formation step In order to facilitate winding of the obtained film, it is preferable to form embossed portions at both ends in the width direction of the film. The method for forming the embossed part is not particularly limited, and examples thereof include a method for forming an embossed part by pressing a roller such as an embossing ring on the film, and a method for forming the embossed part in a non-contact manner. Examples of the method of forming the embossed portion by a non-contact method include a method of forming an embossed portion by irradiating a film with a laser beam; a method of forming an embossed portion by applying a liquid material by an ink jet method, and the like. .

<About the winding process>
The winding step preferably includes a step of winding the retardation film around the core (vibrating winding step) while periodically vibrating at least one of the retardation film and the core in the width direction of the film.

FIG. 3 is a schematic view showing an example of a winding device 20 used in the winding process of the retardation film. 3A is a side view seen from the axial direction of the core 11 of the winding device 20, and FIG. 3B is a plan view seen from above the retardation film 13. As shown in FIG.

The winding device 20 includes a vibration control device 21 for controlling the vibration of the winding core 11, a guide roller 23 for guiding the retardation film 13 to the winding core 11, and the retardation film 13 wound on the winding core 11. And a touch roller 25 for pressing.

The winding core 11 is rotatably installed by a rotating device (not shown). The vibration control device 21 is configured to apply vibration that changes the relative position between the retardation film 13 and the core 11 and to control the vibration state.

The guide roller 23 is a member that rotates following the traveling of the retardation film 13. Thereby, the traveling retardation film 13 is guided to the core 11, and the travel of the retardation film 13 is reduced by the guide roller 23 so that the retardation film 13 can be smoothly supplied to the winding core 11. It has become.

The touch roller 25 is a member that rotates following the rotation of the core 11. Thereby, the retardation film 13 wound around the core 11 is pressed, and the wound retardation film 13 can be prevented from being separated from the core 11.

In the winding device 20 configured as described above, the retardation film 13 is guided to the surface of the core 11 by the guide roller 23. Then, the core 11 is rotated by a rotating device (not shown), and the guided retardation film 13 is wound around the core 11.

In the present invention, it is preferable that the winding process of winding the retardation film 13 around the core 11 includes a vibration winding process. In the vibration winding process, vibration is applied to change the relative position of the retardation film 13 and the core 11 in the width direction of the retardation film 13. The vibration condition can be controlled by the vibration control device 21. FIG. 3B shows an example in which the core 11 is vibrated, but any vibration that changes the relative position of the retardation film 13 and the core 11 in the width direction of the film may be used. The phase difference film 13 may be vibrated; both the phase difference film 13 and the core 11 may be vibrated. Vibration winding is oscillating winding. Oscillating winding is known from Japanese Patent Application Laid-Open No. 2010-150041.

FIG. 4 is a graph for explaining the vibration in the vibration winding process. The x-axis of the graph in FIG. 4 indicates the integrated thickness (mm) of the phase difference film that has been wound at the position of the phase difference film that has started to be wound around the core. That is, the distance between the outermost surface of the phase difference film 13 being wound and the surface of the core 11 is shown, and corresponds to the integrated thickness x of the phase difference film 13 in FIG. 4 is the distance between the center position in the width direction of the phase difference film 13 and the center position in the width direction of the core 11 (distance between the centers of the phase difference film 13 and the core 11) (mm). Corresponding to the center-to-center distance y in FIG.

The vibration in the vibration winding process may be sinusoidal vibration as indicated by curve 2 in FIG. 4; may be rectangular wave vibration as indicated by curve 3; Such vibration may be used. Especially, the vibration as shown by the curve 1 is preferable in order to make the side surface of the roll body difficult to be damaged. Specifically, a function indicating a sinusoidal vibration with an amplitude A and a period T as indicated by a curve 2 is a (x); a function indicating a rectangular wave vibration with an amplitude A and a period T as indicated by a curve 3 b (x); where f (x) is a function indicating the vibration of amplitude A and period T as shown by curve 1, the area surrounded by the function f (x) and the x axis is the function a (x ) And the x-axis, and the vibration represented by the function f (x) that is smaller than the area surrounded by the function b (x) and the x-axis is preferable. When no vibration is applied, the function is represented by a straight line 4 on the x-axis in FIG.

FIG. 5 is a schematic diagram showing an example of a simulation result of the integrated emboss height in the width direction of the roll body of the retardation film. The x-axis in FIG. 5 indicates the position of the retardation film in the width direction of the roll body; the y-axis indicates the integrated embossed height.

As shown in FIG. 5, when no vibration is applied, the graph is shown by line 7; when the vibration is made so as to have a function a (x) (however, the amplitude A is equal to or less than the width of the embossed portion). Becomes the graph shown by the line 6; when it is vibrated so as to be the function f (x), it becomes the graph shown by the line 5.

When vibration is not applied, the embossed portion is laminated at the same position in the width direction of the film, as indicated by line 7, so the accumulated embossed height is accumulated by the number of windings to the height of the embossed portion. Value. On the other hand, when the vibration is applied so as to be the function a (x), as shown by the line 6, although the embossed portion overlaps near the center position of the amplitude A of the vibration, the vibration is not applied. Accumulated emboss height can be reduced. Further, when the vibration is applied so as to be the function f (x), the stay time when the absolute value of the y displacement of the vibration is large becomes relatively long. The overlapping of the parts can be effectively reduced. Thus, the roll body of the retardation film wound up through the vibration winding process can sufficiently suppress the occurrence of deformation even when stored for a long period of time.

The function f (x) may be a function in which the vibration period T and the amplitude A periodically change. Specifically, the function f (x) may be a periodic function in which f (x) = f (x + T); or the function f (x) may be determined by integrating the retardation film with a period T of vibration. The function may be a function that gradually decreases as the thickness x increases; the function f (x) gradually increases as the vibration amplitude A increases as the integrated thickness x of the retardation film increases. Such a function may be used.

Among these, from the viewpoint of preferably suppressing the deformation of the roll body of the retardation film, it is preferable to gradually increase the vibration amplitude A as the integrated thickness of the wound retardation film 13 increases. When the amplitude of vibration is large, it is considered that the overlapping of the embossed portions can be further suppressed and the occurrence of deformation can be further suppressed. At the beginning of winding, since the integrated thickness of the retardation film is small and deformation of the roll body hardly occurs, deformation of the roll body can be sufficiently suppressed even when vibration having a small amplitude is applied. On the other hand, as the retardation film is wound around the core, the roll body is likely to be deformed when the integrated thickness of the wound retardation film increases. Thus, when the integrated thickness of the wound retardation film is large and deformation of the roll body is likely to occur, it is possible to effectively reduce the overlap of the embossed portions by applying vibration with a large amplitude, It is thought that body deformation can be further suppressed.

Further, it is preferable to gradually reduce the vibration period T as the integrated thickness of the wound retardation film increases. If the period of vibration is small, it is considered that the load applied to the retardation film can be reduced. As the retardation film is wound up, the roll body is likely to be deformed when the integrated thickness of the wound up retardation film increases. Thus, when the integrated thickness of the wound retardation film is large and deformation of the roll body is likely to occur, it is possible to effectively reduce the load on the retardation film by applying a vibration having a small period. It is considered that the deformation of the roll body can be further suppressed.

The vibration amplitude A is preferably 0.1 to 1.0% of the film width, and more preferably 0.35 to 0.70%. Specifically, it can be about 2 to 15 mm, preferably about 4 to 10 mm. When the amplitude A is greater than or equal to a certain value, it is easy to reduce the overlap between the embosses and to easily suppress the deformation of the roll body. When the amplitude A is equal to or less than a certain value, it is possible to prevent the side surfaces at both end portions in the axial direction of the roll body from greatly wavy.

The period T of vibration is preferably 0.2 to 10% of the film width, and more preferably 0.3 to 6%. Specifically, it may be about 3 to 160 mm, preferably 3 to 120 mm. When the period T is equal to or greater than a certain value, it is possible to suppress the undulation of the side surfaces of both end portions in the axial direction of the roll body. When the period T is equal to or less than a certain value, it is easy to satisfactorily suppress the deformation of the roll body.

The winding process only needs to include the above-described vibration winding process, and all of the winding processes may be the vibration winding process; and may further include another winding process. In another example of the winding step, the step of winding the retardation film without changing the distance (center distance y) between the center position in the width direction of the retardation film and the center position in the width direction of the core. (Non-vibrating winding process) is included. The non-vibrating winding process and the vibrating winding process can be arbitrarily combined. For example, in the winding process, a non-vibrating winding process may be performed after the vibrating winding process.

Also, from the viewpoint that deformation of the roll body can be satisfactorily suppressed, it is preferable that the start of winding is a non-vibration winding process, the middle is a vibration winding process, and the end of winding is a non-vibration winding process. That is, at the beginning of winding, the non-vibrating winding process can be performed because the accumulated thickness of the retardation film is small and the roll body is hardly deformed. On the other hand, as the winding of the retardation film proceeds and the integrated thickness of the wound retardation film increases, the wound roll body is likely to be deformed. In such a case, the roll shape deterioration can be effectively reduced by performing the vibration winding process. Furthermore, by performing a non-vibrating winding process at the end of winding, the retardation film can be smoothly fed out when the retardation film is fed out from the roll body. For example, if the end of winding is the vibration winding process, when the retardation film starts to be unwound from the obtained roll body, it may not be smoothly fed out due to meandering of the retardation film. On the other hand, by setting the end of winding as a non-vibration winding process, the retardation film can be smoothly fed out immediately after the retardation film starts to be unwound from the roll body.

As described above, the roll body of the retardation film of the present invention includes a step of winding the retardation film around the core while vibrating at least one of the retardation film and the core in the width direction of the film (vibrating winding). It is obtained through the taking process). Thereby, it is possible to reduce the overlap of the embossed portion than the roll body obtained only by the non-vibration winding process of winding without vibrating, and the winding diameter of the width direction both ends and the width direction center portion of the roll body The difference can be reduced. As a result, deformation of the roll body of the retardation film of the present invention can be suppressed. By suppressing the deformation of the roll body, it is possible to suppress a decrease in optical characteristics due to non-uniform tension applied to the wound retardation film or non-uniform film thickness.

In particular, when the film thickness of the retardation film is thin, the strength of the retardation film tends to decrease and the roll body tends to be deformed. Even in such a case, the deformation of the roll body can be preferably suppressed by performing the above-described vibration winding process.

4). Polarizing plate The polarizing plate of the present invention includes a polarizer and the above-described retardation film disposed on at least one surface thereof.

<About the polarizer>
A polarizer is an element that passes only light having a plane of polarization in a certain direction, and a typical polarizer known at present is a polyvinyl alcohol polarizing film. The polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.

The polyvinyl alcohol polarizing film may be a film (preferably a film further subjected to durability treatment with a boron compound) dyed with iodine or a dichroic dye after uniaxially stretching the polyvinyl alcohol film; A film obtained by dying an alcohol film with iodine or a dichroic dye and then uniaxially stretching (preferably a film further subjected to a durability treatment with a boron compound) may be used.

The thickness of the polarizer is preferably 2 to 30 μm, and more preferably 5 to 15 μm in order to reduce the thickness of the polarizing plate.

<About protective film>
The protective film can be disposed on the other surface of the polarizer. Examples of the protective film include a (meth) acrylic resin film, a polyester film, a cellulose ester film, and the like, preferably a cellulose ester film.

Examples of the cellulose ester film include commercially available cellulose ester films (for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC6UA, KC4UY, KC8U, XC8U, KC8UE, KC8U, HC8U -RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, manufactured by Konica Minolta Co., Ltd.) are preferably used.

When reducing the thickness of the protective film, a (meth) acrylic resin film or a polyester film is preferable because of its low moisture permeability.

(Meth) acrylic resin film may be a film containing, as a main component, a homopolymer of methyl methacrylate; or a copolymer of methyl methacrylate and another monomer copolymerizable therewith. Examples of other monomers copolymerizable with methyl methacrylate include: alkyl methacrylates having 2 to 18 carbon atoms in the alkyl moiety; alkyl alkyl esters having 1 to 18 carbon atoms in the alkyl moiety; acrylic acid Α, β-unsaturated acids such as methacrylic acid; unsaturated group-containing dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; aromatic vinyl compounds such as styrene and α-methylstyrene; acrylonitrile, methacrylonitrile And α, β-unsaturated nitriles such as maleic anhydride and glutaric anhydride.

Examples of the polyester film include a polyethylene terephthalate film and a polyethylene naphthalate film.

In the protective film, the in-plane retardation R ₀ measured under the conditions of a measurement wavelength of 590 nm and 23 ° C. and 55% RH is preferably 0 to 20 nm, and more preferably 0 to 10 nm. The retardation Rth in the thickness direction measured under the conditions of a measurement wavelength of 590 nm and 23 ° C. and 55% RH of the protective film is preferably 0 to 80 nm, and more preferably 0 to 50 nm.

The thickness of the protective film can be about 10 to 100 μm, preferably 10 to 80 μm.

The polarizing plate of the present invention can be obtained, for example, through a process in which the retardation film of the present invention is bonded to at least one surface of a polarizer with an adhesive. The adhesive used for the bonding may be a completely saponified polyvinyl alcohol aqueous solution (water glue) or an active energy ray-curable adhesive.

As described above, the retardation film may further contain compounds represented by the above general formulas (A) to (D). The polarizing plate of the present invention including such a retardation film can satisfactorily suppress the deterioration of the polarizer even when stored at high temperature and high humidity.

5. Liquid Crystal Display Device The liquid crystal display device of the present invention includes a liquid crystal cell and a pair of polarizing plates that sandwich the liquid crystal cell. At least one of the pair of polarizing plates includes the above-described retardation film.

FIG. 6 is a schematic diagram showing an example of a basic configuration of the liquid crystal display device. As shown in FIG. 6, the liquid crystal display device 30 of the present invention includes a liquid crystal cell 40, a first polarizing plate 50 and a second polarizing plate 60 that sandwich the liquid crystal cell 40, and a backlight 70.

The display mode of the liquid crystal cell 40 may be various display modes such as STN, TN, OCB, HAN, VA (MVA, PVA), and IPS. For obtaining high contrast, the VA (MVA, PVA) mode is used. It is preferable that

The first polarizing plate 50 includes a first polarizer 51, a protective film 53 (F1) disposed on the viewing side surface of the first polarizer 51, and a liquid crystal cell side of the first polarizer 51. And a retardation film 55 (F2) disposed on the surface.

The second polarizing plate 60 includes a second polarizer 61, a retardation film 63 (F3) disposed on the liquid crystal cell side surface of the second polarizer 61, and a backlight of the second polarizer 61. And a protective film 65 (F4) disposed on the side surface.

The retardation film 55 (F2) and the retardation film 63 (F3) may be the above-described retardation film. Only one of the retardation film 55 (F2) and the retardation film 63 (F3) may be used as the above-described retardation film.

The retardation film of the present invention contains diacetyl cellulose and a retardation increasing agent. Therefore, although it is thin, it has a high retardation value. Furthermore, since the retardation film of the present invention does not require an excessive increase in the amount of addition of the retardation increasing agent, the decrease in film strength can be reduced. Furthermore, deformation of the roll body during storage is suppressed by winding the retardation film through a vibration winding process. Therefore, the dispersion | variation in the retardation value of the retardation film obtained from the roll body after a preservation | save is also reduced. Therefore, the liquid crystal display device including the retardation film of the present invention can perform optical compensation satisfactorily and can have high contrast.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

1. Material of retardation film <Cellulose ester>
The cellulose acetate shown in Table 1 was used.

<Retardation raising agent>
1) A polymer containing a repeating unit derived from the monomer represented by the general formula (1)

2) Compound represented by general formula (2)

3) Compound represented by general formula (3)

4) Compound represented by general formula (4)

5) Compound represented by general formula (5)

6) Compound represented by general formula (6)

<Polarizer degradation inhibitor>
1) Compound represented by general formula (A) Compound f: Knit resin Coumarone G-100N (copolymer represented by general formula (A-2))
2) Compound represented by general formula (B)

3) Compound represented by general formula (C)

4) Compound represented by general formula (D)

<Sugar ester compound>
Benzyl saccharose (degree of substitution of benzyl group 7.5)

2. Production of Retardation Film <Example 1>
(Preparation of fine particle additive solution)
11 parts by mass of fine particles (Aerosil R972V manufactured by Nippon Aerosil Co., Ltd.) and 89 parts by mass of ethanol were stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to obtain a fine particle dispersion.
Next, 99 parts by mass of methylene chloride was charged into the dissolution tank, and 5 parts by mass of the prepared fine particle dispersion was slowly added while stirring sufficiently. The obtained solution was dispersed with an attritor so that the secondary particles had a predetermined particle size, and then filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to obtain a fine particle additive solution. It was.

(Preparation of dope solution)
Among the following components, methylene chloride and ethanol were charged into a pressure dissolution tank, and cellulose ester was further charged while stirring. This was stirred while heating to completely dissolve the cellulose ester. The obtained solution was used as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. Filtration using 244 gave a main dope solution. The obtained main dope solution and the remaining components below were put into a main dissolution vessel and dissolved with stirring to obtain a dope solution.
(Dope solution composition)
Cellulose ester CE2 (diacetyl cellulose having an acetyl substitution degree of 2.0, Mw: 200,000): 100 parts by mass Compound I (retardation increasing agent): 2.0 parts by mass Benzyl saccharose (sugar ester compound): 10 parts by mass Addition of fine particles Liquid: 1 part by mass Methylene chloride: 365 parts by mass Ethanol: 50 parts by mass

The obtained dope solution was uniformly cast on a stainless band support having a dope temperature of 35 ° C. and a temperature of 22 ° C. using a belt casting apparatus. Thereafter, the dope solution on the stainless steel band support was dried until the residual solvent amount became 75%, and then peeled from the stainless steel band support with a peel strength of 130 N / m to obtain a film-like material.

The obtained film-like material was stretched 30% (1.3 times) in the width direction (TD direction) with a tenter while applying heat at 150 ° C. The amount of residual solvent in the film-like material at the start of stretching was 15%. The obtained film was dried while being conveyed by many rolls. The drying temperature was 130 ° C. and the transport tension was 100 N / m. Thereafter, knurling is performed on both ends of the film in the width direction to form an embossed portion having a width of 10 mm and a height of 5 μm as shown in FIG. 2A to obtain a film having a width of 1400 mm and a film thickness of 25 μm. It was.

The obtained knurled film was wound into a roll using a winding device as shown in FIG. 3 while vibrating the core in the film width direction to obtain a roll body. Specifically, the roll 101 was obtained by winding the film 101 at 2900 m with a speed of 80 m / min, a winding initial tension of 140 N, a winding end tension of 90 N, and a nip force of a touch roller of 20 N. The vibration condition in the vibration winding process was set such that the period T = 80 mm and the amplitude A = 5 mm satisfying the function f (x) represented by the curve 61 in FIG. 7 (oscillate A). The shape of the side surface of both end portions in the axial direction of the obtained roll body was wavy. In addition, the curve 62 of FIG. 7 shows the sine wave vibration whose period T and A are the same as the above.

<Examples 2-5, Comparative Examples 1-2>
Except that the type of cellulose ester and the stretching conditions were changed as shown in Table 2, films having a film thickness of 25 μm were produced in the same manner as in Example 1, and roll bodies 102 to 107 were obtained.

<Comparative Examples 3 to 7>
A film having a film thickness of 25 μm was obtained in the same manner as in Example 1 except that the type of cellulose ester and the stretching conditions were changed as shown in Table 2. Then, roll bodies 108 to 112 were obtained in the same manner as in Example 1 except that the obtained film was wound by a non-vibration winding method (straight). The shape of the side surface of both end portions in the axial direction of the obtained roll body was flat.

<Comparative Example 8>
A film having a thickness of 25 μm was produced in the same manner as in Example 5 except that the retardation increasing agent was not contained, and a roll body 113 was obtained.

<Examples 6 to 14>
Except that the type and content of the retardation increasing agent were changed as shown in Table 2, films having a film thickness of 25 μm were prepared in the same manner as in Example 3, and roll bodies 114 to 122 were obtained.

<Comparative Examples 9 to 17>
Except that the type and content of the retardation increasing agent were changed as shown in Table 2, films having a film thickness of 25 μm were prepared in the same manner as in Comparative Example 5, and roll bodies 123 to 131 were obtained.

<Examples 15 to 19, Comparative Example 18>
A film was prepared in the same manner as in Example 1 except that the composition of the cellulose ester and the retardation increasing agent was changed as shown in Table 3, and the stretching conditions and film thickness were changed as shown in Table 3. did. The obtained film was wound up (oscillate A) while applying vibration in the same manner as in Example 1 to obtain roll bodies 132 to 137. The film thickness was adjusted by the dope casting amount, stretch ratio, and the like.

<Comparative Examples 19 to 24>
A film was prepared in the same manner as in Comparative Example 3 except that the composition of the cellulose ester and the retardation increasing agent was changed as shown in Table 3, and the stretching conditions and the film thickness were changed as shown in Table 3. did. The obtained film was wound up in the same manner as in Example 1 to obtain rolls 138 to 143. The film thickness was adjusted by the dope casting amount, stretch ratio, and the like.

<Examples 20 to 27>
Rolls 144 to 151 were obtained in the same manner as in Example 3 except that a polarizer deterioration inhibitor of the type and amount shown in Table 4 was further added.

<Comparative Examples 25 to 32>
Rolls 152 to 159 were obtained in the same manner as in Comparative Example 5 except that a polarizer deterioration inhibitor of the type and amount shown in Table 4 was further added.

<Example 28>
A film was produced in the same manner as in Example 20 except that the type of the polarizer deterioration inhibitor was changed as shown in Table 5. Then, the obtained film was wound (oscillate B) in the same manner as in Example 20 except that the amplitude A of vibration in the vibration winding process was gradually increased in accordance with the increase in the integrated thickness of the wound film. ) And a roll body 160 was obtained. Specifically, the vibration amplitude is 8 mm at the start of winding, the vibration amplitude A is increased, and the vibration amplitude is 10 mm at the end of winding. The period T of vibration was fixed at 80 mm as in Example 20.

<Example 29>
Example 1 except that when the produced film is wound around the core, the amplitude A of vibration in the vibration winding process is gradually increased as the integrated thickness of the film wound around the core increases. In the same manner, a roll film 161 of a retardation film was obtained. Specifically, the amplitude A of vibration at the start of winding was set to 5 mm and gradually increased so that the amplitude A of vibration at the end of winding was set to 7 mm (oscillate C).

<Example 30>
Example when the produced film was wound around the core, except that the vibration period T in the vibration winding process was gradually decreased as the integrated thickness of the film wound on the core increased. In the same manner as in Example 1, a roll body 162 of a retardation film was obtained. Specifically, the vibration period T at the start of winding was set to 160 mm and gradually decreased, and the vibration period T at the end of winding was set to 100 mm (oscillate D).

<Example 31>
A retardation film was produced in the same manner as in Example 1 except that an embossed portion having a shape as shown in FIG.

The production conditions for the films of Examples 1-14 and Comparative Examples 1-17 are shown in Table 2; the production conditions for the films of Examples 15-19 and Comparative Examples 18-24 are shown in Table 3; Examples 20-27 and The production conditions for the films of Comparative Examples 25-32 are shown in Table 4; the production conditions for the films of Examples 28-31 are shown in Table 5.

The retardation (R ₀ and Rth) of the film obtained from the produced roll body was evaluated by the following method.

<Phase difference R ₀ , Rth>
1) The film was drawn out from the obtained roll body, and the film cut out from the central portion in the width direction was conditioned at 23 ° C. and 55% RH. The average refractive index of the film after humidity control was measured with an Abbe refractometer.
2) R ₀ when light having a measurement wavelength of 590 nm was incident on the film after humidity control in parallel with the normal line of the film surface was measured by KOBRA 21ADH, Oji Scientific Co., Ltd.
3) With KOBRA21ADH, light with a measurement wavelength of 590 nm was incident from the angle of θ (incident angle (θ)) with respect to the normal of the film surface with the slow axis in the plane of the film as the tilt axis (rotation axis). The retardation value R (θ) was measured. The retardation value R (θ) was measured at 6 points every 10 °, with θ ranging from 0 ° to 50 °. The in-plane slow axis of the film was confirmed by KOBRA21ADH.
4) nx, ny, and nz were calculated by KOBRA21ADH from the measured R ₀ and R (θ) and the above-described average refractive index and film thickness, and Rth at a measurement wavelength of 590 nm was calculated. The retardation was measured under the conditions of 23 ° C. and 55% RH.

Also, a part of the roll film produced above was cut out to obtain a film before storage. Subsequently, the roll body was preserve | saved for 5 days in 60 degreeC90% RH environment. And the shape of the roll body after a preservation | save was evaluated with the following method.

<Roll body shape>
The surface shape of the obtained roll body was visually observed and evaluated according to the following criteria.
◎: No wrinkles are observed on the roll surface. ○: Weak wrinkles are observed on the roll surface. △: There is remarkable shape deterioration near the roll surface, and wrinkles and dents are observed on the entire surface. There was significant shape deterioration, wrinkles and dents were observed on the entire surface, and shape deterioration reached the inside of the roll.

Next, a part of the film was cut out from the roll body after storage to obtain a film after storage. Then, a polarizing plate and a liquid crystal display device using the film before storage and a polarizing plate and a liquid crystal display device using the film after storage were prepared by the following methods, respectively.

1) Preparation of polarizing plate A polyvinyl alcohol film having a thickness of 30 μm was swollen with water at 35 ° C. The obtained film was immersed in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and further immersed in an aqueous solution at 45 ° C. consisting of 3 g of potassium iodide, 7.5 g of boric acid and 100 g of water. . The obtained film was uniaxially stretched under conditions of a stretching temperature of 55 ° C. and a stretching ratio of 3 times. The uniaxially stretched film was washed with water and dried to obtain a polarizer having a thickness of 5 μm.

As shown below, the film obtained from the produced roll was subjected to alkali saponification treatment, then washed with water, neutralized and washed with water.
Saponification step 2M-NaOH 50 ° C. 90 seconds Water washing step Water 30 ° C. 45 seconds Neutralization step 10% by mass HCl 30 ° C. 45 seconds Water washing step Water 30 ° C. 45 seconds Then, the obtained film was dried at 80 ° C. Similarly, Konica Minoltack KC4UY was prepared as a protective film, and its surface was subjected to alkali saponification treatment.

Then, the prepared film (retardation film) subjected to alkali saponification treatment was bonded to one surface of the prepared polarizer using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive. Similarly, KC4UY subjected to alkali saponification treatment was bonded to the other surface of the polarizer using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive. The bonding was performed so that the transmission axis of the polarizer and the in-plane slow axis of the produced film were parallel. The laminated laminate was dried at 60 ° C. to obtain a polarizing plate.

<Polarizer degradation>
Deterioration of the polarization degree of the polarizing plate produced using the film (film before storage) obtained from the roll body before storage was evaluated by the following methods.
1) The obtained polarizing plate was cut into a size of 4 cm × 4 cm to obtain a polarizing plate sample. The polarizing plate sample was conditioned at 23 ° C. and 55% RH for 24 hours, and then parallel transmittance and orthogonal transmittance were measured at 23 ° C. and 55% RH. The obtained measured values were applied to the following formulas to calculate the polarization degree P0 before storage.
Polarization degree P = ((H0−H90) / (H0 + H90)) 0.5 × 100
(H0: parallel transmittance, H90: orthogonal transmittance)
2) Thereafter, the polarizing plate sample was stored for 1000 hours at 60 ° C. and 90% RH, and then the parallel transmittance and the direct transmittance of the polarizing plate sample were measured in the same manner as described above. The obtained measured values were applied to the above-described formulas, respectively, and the degree of polarization P1000 after storage was calculated.
3) The polarization degree P0 obtained in the above 1) and the polarization degree P1000 obtained in the above 2) were applied to the following formula to calculate the degree of polarization change.
Polarization degree change = P0−P1000
(P0: degree of polarization before forced deterioration, P1000: degree of polarization after 1000 hours of forced deterioration)

The deterioration of the polarizer in the polarizing plate sample was evaluated based on the following criteria.
◎: Polarization degree change rate of less than 3% ○: Polarization degree change rate of 3% or more and less than 5% △: Polarization degree change rate of 5% or more and less than 8% ×: Polarization degree change rate of 8% or more

2) Production of liquid crystal display device A pair of polarizing plates was removed from Sony 40-inch display BRAVIA KLV-40J3000 (VA system). And the produced said polarizing plate was bonded together on both surfaces of the obtained liquid crystal cell, respectively, and the liquid crystal display device was produced. The retardation films of the two polarizing plates (F2 and F3 in FIG. 6) were films obtained from rolls having the same production number. The polarizing film is bonded to the retardation film of the polarizing plate that has been pasted in advance with the slow axis of the prepared film (retarding film) in contact with the liquid crystal cell. The slow axis was made parallel.

Then, viewing angle characteristics and display unevenness of the liquid crystal display device using the film before storage; and viewing angle characteristics and display unevenness of the liquid crystal display device using the film after storage were evaluated by the following methods, respectively.

<Viewing angle characteristics>
The viewing angle of the obtained liquid crystal display device was measured using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH.
A: The viewing angle is very wide. O: The viewing angle is wide. Δ: The viewing angle is narrow. X: The viewing angle is very narrow.

<Display unevenness>
A black image was displayed on the obtained liquid crystal display device. And the display nonuniformity considered to originate in a deformation | transformation of a roll body when visually observing the displayed black image from the front was evaluated.
◎: Unevenness due to deformation of roll body cannot be confirmed at all ◯: Unevenness due to deformation of roll body is slightly confirmed △: Fine unevenness due to deformation of roll body is confirmed ×: Roll body Unevenness due to deformation is clearly confirmed ◎ and ○ are at a level where there is no practical problem.

The evaluation results using the films obtained from the roll bodies of Examples 1 to 14 and Comparative Examples 1 to 17 are shown in Table 6; the films obtained from the roll bodies of Examples 15 to 19 and Comparative Examples 18 to 24 were used. The evaluation results are shown in Table 7; the evaluation results using the films obtained from the roll bodies of Examples 20 to 27 and Comparative Examples 25 to 32 are shown in Table 8; the films obtained from the roll bodies of Examples 28 to 31 are shown. Table 9 shows the evaluation results used.

It can be seen that the films obtained from the roll bodies of Examples 1 to 31 have high retardation values even when the thickness is small. And even if it uses the film (film after a preservation | save) obtained from the roll body preserve | saved in a hot and humid environment, it turns out that the viewing angle characteristic of a liquid crystal display device is favorable, and a display nonuniformity is also suppressed.

On the other hand, it can be seen that when the film obtained from the roll body of Comparative Examples 1 to 32 in Tables 6 to 8 is thin, display unevenness and viewing angle performance are reduced due to deformation of the roll body during storage. Specifically, it can be seen that the film of Comparative Example 1 is too low in strength and cannot sufficiently suppress display unevenness after storage caused by deformation of the roll body during storage. On the other hand, since the film of Comparative Example 2 contains a large amount of retardation increasing agent, it is shown that deformation of the roll body during storage occurs, resulting in display unevenness after storage. In addition, the films of Comparative Examples 3 to 7 were obtained from a roll body wound in a straight manner, and the roll body was deformed during storage, resulting in display unevenness and viewing angle performance after storage. I understand that.

As shown in Comparative Examples 19 to 24 in Table 7, as the film thickness is thinner, display unevenness after storage and viewing angle performance tend to decrease. This is presumably because a film having a small film thickness has low strength and the roll body is likely to be deformed during storage. On the other hand, it can be seen that the films of Examples 15 to 19 wound by oscillating winding hardly cause deformation of the roll body during storage. Thereby, it can be seen that display unevenness and viewing angle performance degradation can be reduced even after storage.

As shown in Comparative Examples 25 to 32 of Table 8, it can be seen that when the film further contains a polarizer deterioration inhibitor, display unevenness and storage angle performance after storage are more likely to occur. This is presumably because the film containing the polarizer deterioration inhibitor has a lower strength and the roll body tends to be deformed during storage. In contrast, the films of Examples 20 to 27 wound by oscillating winding hardly cause deformation of the roll body during storage, and it can be seen that display unevenness and deterioration of viewing angle performance can be reduced even after storage.

As shown in Table 9, the roll body of Example 28 or 29 in which the amplitude A of the oscillating winding is gradually increased with the progress of winding is the same as that of Example 20 or Example 1 in which the amplitude A is constant. It can be seen that there is less deformation during storage than the roll body. Further, it can be seen that the roll body of Example 30 in which the cycle T of the oscillating winding is gradually reduced as the winding progresses is less deformed during storage than the roll body of Example 1 in which the period T is constant. . Further, the roll body of Example 31 in which the shape of the embossed portion is the shape shown in FIG. 2B is more deformed during storage than the roll body of Example 1 having the shape shown in FIG. I understand that there are few. Thereby, it can be seen that the film obtained from the roll body after storage in Examples 28 to 30 can reduce the display unevenness of the liquid crystal display device more than the film obtained from the roll body in Example 20 or Example 1.

This application claims priority based on Japanese Patent Application No. 2014-095443 filed on May 2, 2014. The contents described in the application specification and the drawings are all incorporated herein.

DESCRIPTION OF SYMBOLS 10 Roll body 11 Core 13 Phase difference film 13A Embossing part 20 Winding device 21 Vibration control device 23 Guide roller 25 Touch roller 30 Liquid crystal display device 40 Liquid crystal cell 50 First polarizing plate 51 First polarizer 53 Protective film ( F1)
55 Retardation film (F2)
60 Second polarizing plate 61 Second polarizer 63 Retardation film (F3)
65 Protective film (F4)
70 Backlight

Claims

A roll body obtained by winding a retardation film having an embossed portion at both ends in the width direction in the longitudinal direction of the film,
The retardation film includes diacetyl cellulose as a main component and a retardation increasing agent,
A roll body of a retardation film, wherein at least a part of a side surface shape of both end portions in the axial direction of the roll body is wavy.
2. The roll of retardation film according to claim 1, wherein the retardation film has a thickness of 15 to 35 μm.
The retardation film is defined by the following formula (I) and has an in-plane retardation R 0 of 20 to 130 nm measured at a measurement wavelength of 590 nm, and is defined by the following formula (II) and measured. 2. The retardation film roll according to claim 1, wherein the retardation Rth in the thickness direction measured at a wavelength of 590 nm is 100 to 300 nm.
Formula (I) R 0 = (nx−ny) × t (nm)
Formula (II) Rth = {(nx + ny) / 2−nz} × t (nm) (in formulas (I) and (II)
nx represents the refractive index in the slow axis direction x where the refractive index is maximum in the in-plane direction of the film; ny represents the refractive index in the direction y perpendicular to the slow axis direction x in the in-plane direction of the film. Nz represents the refractive index in the thickness direction z of the film; t (nm) represents the thickness of the film)
2. The retardation film roll according to claim 1, wherein the content of the retardation increasing agent is 1 to 10 parts by mass with respect to 100 parts by mass of the diacetylcellulose.
The retardation film includes a polymer having a repeating structure derived from a monomer represented by the following general formula (A), a compound represented by the general formula (B), a compound represented by the general formula (C), and a general The roll body of retardation film of Claim 1 which further contains 1 or more chosen from the group which consists of a compound represented by Formula (D).

(In general formula (A),
R 1 and R 2 each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;
R 3 represents a substituent;
Ring A represents a 5 or 6 membered ring;
n represents an integer of 1 to 4, and when n is 2 or more, a plurality of R 3 may be the same or different from each other)

(In the general formula (B),
R 1 represents a hydrogen atom or a substituent;
R 2 represents a substituent represented by the following general formula (B-1);
n1 represents an integer of 0 to 4, and when n1 is 2 or more, a plurality of R 1 may be the same or different from each other;
n2 represents an integer of 1 to 5, and when n2 is 2 or more, a plurality of R 2 may be the same or different)

(In the general formula (B-1),
A represents a substituted or unsubstituted aromatic ring;
R 3 and R 4 each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a substituent represented by the general formula (B-2);
R 5 represents a single bond or an alkylene group having 1 to 5 carbon atoms;
X represents a substituted or unsubstituted aromatic ring;
n3 represents an integer of 0 to 10, and when n3 is 2 or more, a plurality of R 5 and X may be the same or different from each other)

(In the general formula (B-2),
X represents a substituted or unsubstituted aromatic ring;
R 6 , R 7 , R 8 , and R 9 each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
n5 represents an integer of 1 to 11, and when n5 is 2 or more, a plurality of R 6 , R 7 , R 8 and X may be the same or different)

(In the general formula (C),
R 26 represents an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms;
R 27 and R 28 each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms;
R 26 and R 27 may each have a substituent)

(In general formula (D),
R represents a substituent;
m and n each independently represents an integer of 1 to 3)
A step of preparing a long retardation film including diacetylcellulose as a main component and a retardation increasing agent and having embossed portions provided at both ends in the width direction;
Winding the phase difference film into a roll around a core,
The winding step includes a vibration winding step of winding the retardation film around the core while periodically vibrating at least one of the retardation film and the core in the width direction of the retardation film. A method for producing a roll of retardation film.
The method for producing a roll body of a retardation film according to claim 6, wherein the amplitude of vibration in the vibration winding process is increased as the integrated thickness of the phase difference film to be wound increases.
The method for producing a roll body of a retardation film according to claim 6, wherein a period of vibration in the vibration winding process is reduced as an integrated thickness of the phase difference film to be wound is increased.
A polarizing plate comprising: a polarizer; and a retardation film obtained from the roll body according to claim 1 disposed on at least one surface of the polarizer.
Including a liquid crystal cell, a first polarizing plate disposed on one surface of the liquid crystal cell, and a second polarizing plate disposed on the other surface of the liquid crystal cell,
The first polarizing plate includes a first polarizer, a protective film F1 disposed on a surface of the first polarizer opposite to the liquid crystal cell, and the liquid crystal cell of the first polarizer. Including a protective film F2 disposed on the side surface,
The second polarizing plate is opposite to the second polarizer, the protective film F3 disposed on the surface of the second polarizer on the liquid crystal cell side, and the liquid crystal cell of the second polarizer. Including a protective film F4 disposed on the side surface,
The liquid crystal display device in which at least one of the said protective films F2 and F3 contains the retardation film obtained from the roll body of Claim 1.