WO2015137367A1 - Optical film roll-body and method for manufacturing same, polarizing plate, and liquid crystal display device - Google Patents

Abstract

The purpose of the present invention is to provide an optical film roll-body for which deformation of the roll body is mitigated and an increase in haze is mitigated. This optical film roll-body is attained by rolling up an optical film in the lengthwise direction thereof, the optical film being 15-45µm in thickness and having embossed portions on both ends thereof in the widthwise direction. The optical film contains a cellulose ester and a compound of 0.05-5 mass% expressed by general formula (1), and the side surfaces of the roll body on both ends in the axial direction have a wave shape.

Description

Optical film roll and manufacturing method thereof, polarizing plate and liquid crystal display device

The present invention relates to a roll body of an optical film, a manufacturing method thereof, a polarizing plate and a liquid crystal display device.

In recent years, there has been an increasing demand for liquid crystal display devices as liquid crystal displays for mobile devices such as smartphones and tablet terminals. Such a liquid crystal display device is required to be thin, and an optical film such as a polarizing plate protective film constituting the liquid crystal display device is also required to be thin.

As the polarizing plate protective film, for example, a cellulose ester film is used. Such a film is generally stored as a roll obtained by winding a long film into a roll around a core after producing a long film by a solution casting method or the like. And in order to suppress the shift | offset | difference (winding deviation | shift) etc. of the wound film end part, the embossed part is given to the width direction both ends of the film wound up.

However, it is known that when a long film having an embossed portion at both ends in the width direction is wound by a normal method, the roll body is easily deformed. On the other hand, a method (oscillate winding) has been proposed in which the film or the core is wound while being periodically vibrated in the width direction of the film (for example, Patent Document 1).

JP 2010-150041 A

The present inventors have found that the roll body is easily deformed particularly when a thin film is wound by a normal method. Specifically, the deformation of the roll body in the present invention means that 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 bends in the vertical direction. It means that such a big wrinkle occurs.

The reason why such deformation of the roll body becomes prominent particularly when the film thickness of the optical film is thin is not necessarily clear, but is considered as follows. That is, as the film thickness of the optical film is thinner, 1) the ratio of the height of the embossed part to the film thickness of the optical film becomes larger, and the difference in the winding diameter between the widthwise central part and the widthwise both ends becomes larger. 2) It is considered that the strength of the optical film is low and it is difficult to support the weight of the optical film.

Such deformation of the roll body can be improved by performing a winding method (oscillate winding) while applying vibration as described above.

However, in the method of winding while applying vibration, the films are periodically vibrated in the width direction, so that the films easily rub against each other; in particular, the embossed part and the film surface on which the embossed part is not provided. As a result, there was a problem that the film surface on which the embossed portion was not provided was likely to be finely scratched and haze was likely to increase. A film having increased haze tends to deteriorate display performance such as contrast of a liquid crystal display device.

This invention is made | formed in view of the said situation, and it aims at providing the roll body of the optical film by which the deformation | transformation of the roll body was suppressed and the increase in haze was suppressed.

（一般式（１）中、
　Ｌは、エステル結合、アミド結合、カルボニル基、またはエステル結合、アミド結合もしくはカルボニル基とアルキレン基、窒素原子、酸素原子、硫黄原子、亜鉛原子、カルシウム原子およびマグネシウム原子からなる群より選ばれる一以上とを組み合わせた２価の基を表し；
　Ｒ_１は、炭素原子数８以上２６以下のアルキル基、または炭素原子数８以上２６以下のアルケニル基を表し；
　Ｒ_２は、水素原子、炭素原子数８以上２６以下のアルキル基、または炭素原子数８以上２６以下のアルケニル基を表す）
　前記ロール体の軸方向両端部の側面形状が、波状になっている、光学フィルムのロール体。
　［２］　前記一般式（１）のＬは、－Ｃ（＝Ｏ）－Ｏ－、－Ｃ（＝Ｏ）ＮＨ－、
　－Ｃ（＝Ｏ）－Ｏ－Ｒ_３－Ｏ－Ｃ（＝Ｏ）－、－Ｃ（＝Ｏ）－ＮＨ－Ｒ_３－ＮＨ－Ｃ（＝Ｏ）－（Ｒ_３は、炭素数１～５のアルキレン基）、
　－Ｃ（＝Ｏ）－Ｏ－Ｍ－Ｏ－Ｃ（＝Ｏ）－（Ｍは、亜鉛原子、カルシウム原子またはマグネシウム原子）、
　－Ｃ（＝Ｏ）－Ｒ_４－Ｏ－Ｒ_４－Ｃ（＝Ｏ）－、－Ｃ（＝Ｏ）－Ｒ_４－Ｓ－Ｒ_４－Ｃ（＝Ｏ）－、－Ｃ（＝Ｏ）－Ｒ_４－ＮＨ－Ｒ_４－Ｃ（＝Ｏ）－（Ｒ_４は、炭素数１～５のアルキレン基）、および
　－Ｃ（＝Ｏ）－Ｒ_５－Ｃ（＝Ｏ）－（Ｒ_５は、炭素数１～５のアルキレン基）からなる群より選ばれる基である、［１］に記載の光学フィルムのロール体。
　［３］　前記一般式（１）のＲ_１およびＲ_２は、それぞれ独立して炭素原子数８以上２６以下の直鎖状のアルキル基、または炭素原子数８以上２６以下の直鎖状のアルケニル基である、［１］または［２］に記載の光学フィルムのロール体。
　［４］　前記一般式（１）のＬは、硫黄原子を含む、［１］～［３］のいずれかに記載の光学フィルムのロール体。
　［５］　前記光学フィルムは、脂肪族ジオールと脂肪族ジカルボン酸とを重縮合して得られる脂肪族ポリエステル化合物をさらに含む、［１］～［４］のいずれかに記載の光学フィルムのロール体。
　［６］　前記光学フィルムの、下記式（Ｉ）で定義され、かつ測定波長５９０ｎｍで測定される面内方向のリターデーションをＲｏ（５９０）とし、下記式（II）で定義され、かつ測定波長５９０ｎｍで測定される厚み方向のリターデーションをＲｔｈ（５９０）としたとき、｜Ｒｏ（５９０）｜≦５ｎｍ、｜Ｒｔｈ（５９０）｜≦５ｎｍを満たす、［１］～［５］のいずれかに記載の光学フィルムのロール体。
　式（Ｉ）　Ｒｏ＝（ｎｘ－ｎｙ）×ｔ（ｎｍ）
　式（II）　Ｒｔｈ＝｛（ｎｘ＋ｎｙ）／２－ｎｚ｝×ｔ（ｎｍ）
（式（Ｉ）および（II）において、
　ｎｘは、フィルムの面内方向において屈折率が最大になる遅相軸方向ｘにおける屈折率を表し；ｎｙは、フィルムの面内方向において前記遅相軸方向ｘと直交する方向ｙにおける屈折率を表し；ｎｚは、フィルムの厚み方向ｚにおける屈折率を表し；ｔ（ｎｍ）は、フィルムの厚みを表す）
　［７］　セルロースエステルと、前記セルロースエステル１００質量部に対して０．０５～５質量部の下記一般式（１）で表される化合物とを含み、幅方向両端部にエンボス部が設けられた厚み１５～４５μｍの長尺状の光学フィルムを準備する工程と、

（一般式（１）中、
　Ｌは、エステル結合、アミド結合、カルボニル基、またはエステル結合、アミド結合もしくはカルボニル基とアルキレン基、窒素原子、酸素原子、硫黄原子、亜鉛原子、カルシウム原子およびマグネシウム原子からなる群より選ばれる一以上とを組み合わせた２価の基を表し；
　Ｒ_１は、炭素原子数８以上２６以下のアルキル基または炭素原子数８以上２６以下のアルケニル基を表し；
　Ｒ_２は、水素原子、炭素原子数８以上２６以下のアルキル基または炭素原子数８以上２６以下のアルケニル基を表す）
　前記光学フィルムを巻芯にロール状に巻き取る工程とを含み、
　前記巻き取る工程は、前記光学フィルムと前記巻芯の少なくとも一方を、前記光学フィルムの幅方向に周期的に振動させながら、前記光学フィルムを前記巻芯に巻き取る工程を含む、光学フィルムのロール体の製造方法。 [1] A roll of an optical film obtained by winding an optical film having a thickness of 15 to 45 μm having embossed portions at both ends in the width direction in the longitudinal direction of the film, wherein the optical film comprises cellulose ester, 0.05 to 5 parts by mass of the compound represented by the following general formula (1) with respect to 100 parts by mass of the cellulose ester,

(In general formula (1),
L is an ester bond, an amide bond, a carbonyl group, or one or more selected from the group consisting of an ester bond, an amide bond or a carbonyl group and an alkylene group, a nitrogen atom, an oxygen atom, a sulfur atom, a zinc atom, a calcium atom, and a magnesium atom. Represents a divalent group in combination with;
R ₁ represents an alkyl group having 8 to 26 carbon atoms, or an alkenyl group having 8 to 26 carbon atoms;
R ₂ represents a hydrogen atom, an alkyl group having 8 to 26 carbon atoms, or an alkenyl group having 8 to 26 carbon atoms)
The roll body of the optical film in which the side surface shape of the axial direction both ends of the said roll body is wavy.
[2] L in the general formula (1) is —C (═O) —O—, —C (═O) NH—,
—C (═O) —O—R ₃ —O—C (═O) —, —C (═O) —NH—R ₃ —NH—C (═O) — (R ₃ is a group having 1 to 5 alkylene groups),
-C (= O) -OMO-C (= O)-(M is a zinc atom, a calcium atom or a magnesium atom),
—C (═O) —R ₄ —O—R ₄ —C (═O) —, —C (═O) —R ₄ —SR ₄ —C (═O) —, —C (═O) —R ₄ —NH—R ₄ —C (═O) — (R ₄ is an alkylene group having 1 to 5 carbon atoms), and —C (═O) —R ₅ —C (═O) — (R ₅ Is a group selected from the group consisting of alkylene groups having 1 to 5 carbon atoms).
[3] R ₁ and R _{2 in} the general formula (1) are each independently a linear alkyl group having 8 to 26 carbon atoms, or a straight chain alkenyl having 8 to 26 carbon atoms. The roll body of the optical film according to [1] or [2], which is a group.
[4] The roll of optical film according to any one of [1] to [3], wherein L in the general formula (1) contains a sulfur atom.
[5] The optical film roll according to any one of [1] to [4], wherein the optical film further includes an aliphatic polyester compound obtained by polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid. .
[6] The retardation of the optical film defined by the following formula (I) and measured in the in-plane direction measured at a measurement wavelength of 590 nm is Ro (590), defined by the following formula (II), and the measurement wavelength When the thickness direction retardation measured at 590 nm is Rth (590), | Ro (590) | ≦ 5 nm and | Rth (590) | ≦ 5 nm are satisfied, and any one of [1] to [5] The roll body of the optical film as described.
Formula (I) Ro = (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)
[7] A cellulose ester and 0.05 to 5 parts by mass of a compound represented by the following general formula (1) with respect to 100 parts by mass of the cellulose ester, and embossed portions are provided at both ends in the width direction Preparing a long optical film having a thickness of 15 to 45 μm;

(In general formula (1),
L is an ester bond, an amide bond, a carbonyl group, or one or more selected from the group consisting of an ester bond, an amide bond or a carbonyl group and an alkylene group, a nitrogen atom, an oxygen atom, a sulfur atom, a zinc atom, a calcium atom, and a magnesium atom. Represents a divalent group in combination with;
R ₁ represents an alkyl group having 8 to 26 carbon atoms or an alkenyl group having 8 to 26 carbon atoms;
R ₂ represents a hydrogen atom, an alkyl group having 8 to 26 carbon atoms, or an alkenyl group having 8 to 26 carbon atoms)
Winding the optical film into a roll around a core,
The winding step includes a step of winding the optical film around the core while periodically vibrating at least one of the optical film and the core in the width direction of the optical film. Body manufacturing method.

[8] A polarizing plate comprising an optical film obtained from the roll according to any one of [1] to [6].
[9] A liquid crystal display device comprising an optical film obtained from the roll body according to any one of [1] to [6].
[10] A first polarizing plate, a liquid crystal cell, a second polarizing plate, and a backlight are included in this order, and the first polarizing plate includes the first polarizer and the first polarizer. Including a protective film F1 disposed on the surface opposite to the liquid crystal cell and a protective film F2 disposed on the liquid crystal cell side surface of the first polarizer, The second polarizer, the protective film F3 disposed on the surface of the second polarizer on the liquid crystal cell side, and the surface of the second polarizer on the surface opposite to the liquid crystal cell. The liquid crystal display device according to [9], including a protective film F4, wherein at least one of the protective films F2 and F3 includes the optical film.
[11] The liquid crystal display device according to [10], wherein the liquid crystal cell is an IPS mode or FFS mode liquid crystal cell.
[12] The liquid crystal display device according to any one of [9] to [11], wherein the diagonal length of the display area is 10 inches or less.
[13] The liquid crystal display device according to [12], further including a rechargeable battery.

According to the present invention, it is possible to provide a roll body of an optical film in which deformation of the roll body is suppressed and an increase in haze is suppressed.

It is a schematic diagram which shows an example of the roll body of the optical 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 an optical 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 an optical film. It is a schematic diagram which shows an example of a small-sized liquid crystal display device. It is a graph which shows the vibration conditions in the vibration winding process in an Example.

As described above, the deformation of the roll of the optical film can be improved by winding the optical film while periodically vibrating the film or the core in the width direction of the film (oscillate winding). However, in the oscillating winding, the optical film is periodically vibrated in the width direction, so that the films are rubbed with each other and fine scratches are easily formed on the film surface on which the embossed portion is not formed, and haze is likely to increase.

On the other hand, the present inventors can impart good slipperiness to the film while allowing the optical film to contain the compound represented by the general formula (1), while being well compatible with the cellulose ester. I found it. Thereby, it discovered that the increase in the haze of an optical film can be suppressed, suppressing a deformation | transformation of a roll body. The present invention has been made based on such knowledge.

That is, the optical film of the present invention preferably contains a cellulose ester and a compound represented by the general formula (1).

1. Optical film The optical film of this invention contains a cellulose ester and the compound represented by General formula (1) as above-mentioned.

<About cellulose ester>
The cellulose ester is a compound obtained by esterifying cellulose and at least one of an aliphatic carboxylic acid having 2 to 22 carbon atoms and an aromatic carboxylic acid.

Examples of the cellulose ester include cellulose triacetate, cellulose diacetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose benzoate, and cellulose acetate benzoate. Among them, those having low retardation are preferable, and cellulose triacetate is preferable.

The total degree of substitution of acyl groups in the cellulose ester is about 2.0 to 3.0, preferably 2.5 to 3.0, more preferably 2.7 to 3.0, and even more preferably 2.8 to 3.0. 2.95. In order to reduce the retardation development property, it is preferable to increase the total substitution degree of the acyl group.

The number of carbon atoms of the acyl group contained in the cellulose ester is preferably 2 to 7, and more preferably 2 to 4. In order to obtain good heat resistance, the acyl group contained in the cellulose ester preferably contains an acetyl group. The substitution degree of the acyl group having 3 or more carbon atoms is preferably 0.9 or less, and more preferably 0.

The degree of substitution of the acyl group of the cellulose ester can be measured by the method prescribed in ASTM-D817-96.

The weight average molecular weight of the cellulose ester 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 the cellulose ester is preferably 1.0 to 4.5.

The weight average molecular weight and molecular weight distribution of the cellulose ester 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 compound represented by the general formula (1)>
The compound represented by the general formula (1) may have a function of increasing the slipperiness of the film.

L in the general formula (1) includes at least an ester bond (—C (═O) O—), an amide bond (—C (═O) NH—) or a carbonyl group (—C (═O) —). Represents a valent group. These carbonyl groups can impart good affinity with the cellulose ester to the compound represented by the general formula (1). Specifically, L is an ester bond, an amide bond, a carbonyl group, or “from an ester bond, an amide bond or a carbonyl group, an alkylene group, a nitrogen atom, an oxygen atom, a sulfur atom, a zinc atom, a calcium atom, and a magnesium atom. Represents a divalent group in combination with one or more selected from the group consisting of; an ester group, an amide bond or a carbonyl group, an alkylene group, “A divalent group in combination with one or more selected from the group consisting of a nitrogen atom, an oxygen atom, a sulfur atom, a zinc atom, a calcium atom, and a magnesium atom”.

Example of “a divalent group in which an ester bond, an amide bond or a carbonyl group is combined with one or more selected from the group consisting of an alkylene group, a nitrogen atom, an oxygen atom, a sulfur atom, a zinc atom, a calcium atom and a magnesium atom” Is
—C (═O) —O—R ₃ —O—C (═O) —, —C (═O) —NH—R ₃ —NH—C (═O) — (R ₃ is a group having 1 to 5 alkylene groups);
-C (= O) -OMO-C (= O)-(M is a zinc atom, a calcium atom or a magnesium atom);
—C (═O) —R ₄ —O—R ₄ —C (═O) —, —C (═O) —R ₄ —SR ₄ —C (═O) —, —C (═O) —R ₄ —NH—R ₄ —C (═O) — (R ₄ is an alkylene group having 1 to 5 carbon atoms); and —C (═O) —R ₅ —C (═O) — (R ₅ Includes an alkylene group having 1 to 5 carbon atoms. Among these, from the viewpoint of improving the thermal durability of the optical film, L is preferably a group containing a sulfur atom, and —C (═O) —R ₄ —SR ₄ —C (═O) -Is more preferable.

R _{1 in the} general formula (1) represents an alkyl group having 8 to 26 carbon atoms or an alkenyl group having 8 to 26 carbon atoms. The number of carbon atoms in the alkyl group and alkenyl group is more preferably 10 or more and 26 or less because good slipperiness is easily obtained. The alkyl group and alkenyl group may be linear or branched, and are preferably linear because good slipperiness is easily obtained.

R _{2 in the} general formula (1) represents a hydrogen atom, an alkyl group having 8 to 26 carbon atoms, or an alkenyl group having 8 to 26 carbon atoms; An alkyl group having 8 to 26 carbon atoms or an alkenyl group having 8 to 26 carbon atoms. The number of carbon atoms in the alkyl group and alkenyl group is more preferably 10 or more and 26 or less because good slipperiness is easily obtained. The alkyl group and alkenyl group may be linear or branched, and are preferably linear because good slipperiness is easily obtained.

When R ₂ is a hydrogen atom, —LR ₂ can be —C (═O) OH, —C (═O) NH ₂ or the like.

R ₁ and R ₂ may further have a substituent such as an OH group, if necessary. R ₁ and R ₂ may be the same as or different from each other.

Examples of the compound represented by the general formula (1) include the following.

The content of the compound represented by the general formula (1) is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the cellulose ester. When the content of the compound represented by the general formula (1) is a certain level or more, sufficient slipperiness can be imparted to the film. Thereby, even if the vibration winding process mentioned later is performed, the increase in the external haze of the film obtained can be suppressed. On the other hand, when the content of the compound represented by the general formula (1) is below a certain level, it is possible to suppress the roll shape from being lowered due to the optical film becoming excessively slippery.

The optical film of the present invention may further contain a polyester compound in order to adjust the plasticity and retardation of the film.

<About polyester compounds>
The polyester compound is a compound obtained by polycondensation of a dicarboxylic acid and a diol. The dicarboxylic acid may be one or more selected from the group consisting of aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and aromatic dicarboxylic acids. The diol may be one or more selected from the group consisting of aliphatic diols, alkyl ether diols, alicyclic diols, and aromatic diols. Among them, a group consisting of a dicarboxylic acid selected from the group consisting of an aliphatic dicarboxylic acid and an alicyclic dicarboxylic acid, an aliphatic diol, an alkyl ether diol, and an alicyclic diol because the retardation can be made difficult to develop. A polyester compound obtained by polycondensation with a more selected diol is preferred; a polyester compound (aliphatic polyester compound) obtained by polycondensation of an aliphatic dicarboxylic acid and an aliphatic diol is more preferred.

That is, the polyester compound is preferably represented by the general formula (2) or (3).
General formula (2):

G in the general formula (2) represents a group derived from an aliphatic diol or an alkyl ether diol. The aliphatic diol preferably has 2 to 12 carbon atoms. Examples of aliphatic diols include ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1, 5-pentanediol, 1,6-hexanediol, 1,5-pentylene glycol and the like, preferably ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, and 1,6-hexanediol.

The alkyl ether diol preferably has 4 to 12 carbon atoms. Examples of the alkyl ether diol include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like. One type of aliphatic diol or alkyl ether diol may be used, or two or more types may be combined.

A in the general formula (2) represents a group derived from an aliphatic dicarboxylic acid or an alicyclic dicarboxylic acid. The aliphatic dicarboxylic acid preferably has 4 to 12 carbon atoms. Examples of the aliphatic dicarboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid and the like. One type of aliphatic dicarboxylic acid or alicyclic dicarboxylic acid may be used, or two or more types may be combined.

B _{1 in the} general formula (2) represents a group derived from an aliphatic monocarboxylic acid or an alicyclic monocarboxylic acid. The aliphatic monocarboxylic acid preferably has 1 to 12 carbon atoms. Examples of aliphatic monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, Acetic acid is preferred because it contains unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid, and has good compatibility with cellulose esters.

It is preferable that all of B ₁ , G and A in the general formula (2) do not contain an aromatic ring in order to make it difficult to develop a phase difference. m represents the number of repetitions, and is preferably 1 or more and 170 or less.

Examples of the polyester compound represented by the general formula (2) include those shown in Table 1.

General formula (3):

G and A in the general formula (3) are defined similarly to G and A in the general formula (2), respectively. B _{2 in the} general formula (3) represents a group derived from an aliphatic monoalcohol or an alicyclic monoalcohol. The aliphatic monoalcohol preferably has 1 to 12 carbon atoms. Examples of aliphatic monoalcohol include methanol, ethanol, propanol, isopropanol, etc .; examples of alicyclic monoalcohol include cyclohexyl alcohol and the like.

It is preferable that none of B ₂ , G and A in the general formula (3) contains an aromatic ring in order to make it difficult to develop a phase difference. n represents the number of repetitions and is preferably 1 or more and 170 or less.

Examples of the polyester compound represented by the general formula (3) include those shown in Table 2.

The weight average molecular weight Mw of the polyester compound is preferably 20000 or less, more preferably 5000 or less, and still more preferably 3000 or less from the viewpoint of improving the compatibility with the cellulose ester. On the other hand, from the viewpoint of suppressing the volatilization of the polyester compound during film formation, the weight average molecular weight Mw of the polyester compound may be 400 or more, preferably 700 or more, more preferably 1000 or more.

The content of the polyester compound is preferably 1 to 45% by mass, more preferably 2 to 30% by mass with respect to the cellulose ester, from the viewpoint of easy adjustment of the plasticity and retardation of the film. More preferably, it is ˜25% by mass, and most preferably 10˜20% by mass.

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

<About UV absorber>
The ultraviolet absorber may be a benzotriazole compound, a 2-hydroxybenzophenone compound, a salicylic acid phenyl ester compound, or the like. Specifically, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- Triazoles such as (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4 -Benzophenones such as methoxybenzophenone.

The UV absorber may be a commercially available product. Examples thereof include Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, and Tinuvin 928 manufactured by BASF Japan, or 2, 2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (molecular weight 659; examples of commercially available products are manufactured by ADEKA Corporation LA31) and the like.

In the case where the optical film is disposed on the surface of the polarizer on the liquid crystal cell side (when used as a protective film 135 (F2) or 153 (F3) in FIG. 6 described later), an ultraviolet inhibitor is not essential. The content of the absorbent can be about 0 to 0.5% by mass with respect to the cellulose ester. On the other hand, when the polarizer is disposed on the side opposite to the liquid crystal cell (when used as a protective film 133 (F1) or 155 (F4) in FIG. 6 to be described later), the content of the ultraviolet light inhibitor is cellulose. The mass ratio can be about 1 ppm to 5.0%, preferably about 0.5 to 3.0% with respect to the ester.

<About matting agent>
The matting agent can impart further slipperiness to the optical 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 the cellulose ester.

<About physical properties of optical films>
(Haze)
As described above, the optical film of the present invention includes a compound represented by the general formula (1). Thereby, the slipperiness of the film when winding the optical film by oscillating winding can be enhanced. Thereby, increase in haze due to fine scratches on the film surface by rubbing the films can be suppressed.

That is, the haze of the optical film is preferably 0.5% or less, and more preferably 0.3% or less. The haze of the optical film means the total haze that combines the external haze and the internal haze. When the haze of the optical film is in the above range, good contrast can be easily obtained in the display device.

The haze of the optical film can be measured by the following procedure. That is, the film is drawn out from the roll body of the optical film, cut into 10 points and 4 cm × 4 cm at equal intervals in the width direction, and conditioned at 23 ° C. and 55% RH, respectively. The haze of the obtained film is measured with a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K-7136. The average value of the ten measured values obtained is defined as “haze”.

The haze of the optical film can be adjusted by the type and content of the compound represented by the general formula (1). In order to reduce the haze, it is preferable that the number of carbon atoms of the alkyl group or alkenyl group represented by R ₁ and R ₂ in the general formula (1) be a certain value or linear.

(Retardation)
The retardation R ₀ in the in-plane direction measured under the conditions of a measurement wavelength of 590 nm and 23 ° C. and 55% RH of the optical film is preferably −10 nm to 10 nm, and preferably −5 nm to 5 nm. More preferred. The retardation Rth in the thickness direction measured under conditions of a measurement wavelength of 590 nm and 23 ° C. and 55% RH of the optical film is preferably from −10 nm to 10 nm, and more preferably from −5 nm to 5 nm. . An optical film having such a retardation value is suitable as, for example, a retardation film (F2 or F3) of an IPS mode liquid crystal display device. In particular, by setting the phase difference within the above range, the contrast and viewing angle of the IPS mode liquid crystal display device can be improved.

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 optical film is conditioned at 23 ° C. and 55% RH. The average refractive index of the optical film after humidity adjustment is measured with an Abbe refractometer or the like.
The optical 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 optical film is set as the tilt axis (rotation axis), and light having a measurement wavelength of 590 nm from the angle normal to the surface of the film (incident angle (θ)) The retardation value R (θ) when 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 is an axis having the maximum refractive index in the film plane, and 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.

(Thickness)
The thickness of the optical film is from 15 to 45 μm, preferably from 15 to 28 μm, from the viewpoint of thinning the polarizing plate, roll shape, and haze of the film.

2. Roll body of optical film The roll body of the optical film of the present invention is obtained by winding a long optical film in the longitudinal direction of the film.

FIG. 1 is a schematic view showing an example of a roll body of the optical 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), an optical film roll 10 includes a core 11, and a long optical film 13 wound around the core 11 and having embossed portions 13A at both ends in the width direction. including.

In the present invention, the optical film is wound while vibrating at least one of the film or the core in the width direction of the film. 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. Thereby, the side surface shape of the axial direction both ends of the roll body 10 is wavy. 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, the shape of both end portions in the axial direction of the cross section along the axial direction of the roll body. Says that it is wavy.

The embossed portion 13A is provided at both ends of the optical film 13 in the width direction. The width of the embossed portion 13A can be, for example, 0.2 to 6%, preferably 0.3 to 2% with respect to the entire width of the optical 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 optical 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 an optical 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 optical 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 optical film 13 can be, for example, 1000 to 6000 mm, preferably 1400 to 4000 mm. The winding length of the optical film 13 can be set to 100 to 10,000 m, for example.

3. Manufacturing method of roll body of optical film The roll body of the optical film of the present invention includes: 1) a step of preparing a long optical film having embossed portions at both ends in the width direction; and 2) a step of winding up the optical film. including. And 2) the step of winding up the optical film includes the step of winding the optical film around the core (vibrating winding step) while periodically vibrating at least one of the optical film and the core in the width direction of the film. It is preferable to include.

<About the process of preparing a long optical film>
The long optical film is manufactured 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. sell.

A method for producing a long optical film by a solution casting method (casting) includes: 1-1) a step of obtaining a dope containing a cellulose ester; and 1-2) drying the dope after casting the dope on a support. A step of obtaining a film-like material, 1-3) a step of peeling the film-like material from the support, and 1-5) a step of forming embossed portions at both ends in the width direction of the peeled film-like material. Including a step of 1-4) stretching a film-like material between 1-3) and 1-5) as necessary.

1-1) Dissolution Step The organic solvent used for the preparation of the dope solution can be used without limitation as long as it can sufficiently dissolve the above components such as cellulose ester. 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 cellulose ester and the like includes a method performed at normal pressure, a method performed below the boiling point of the main solvent, a method performed under pressure above the boiling point of the main solvent, and a method performed under pressure above 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 (vibrating winding step) of winding the optical film around the core while periodically vibrating at least one of the optical 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 optical film. FIG. 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 optical film 13.

The winding device 20 presses the vibration control device 21 for controlling the vibration of the winding core 11, the guide roller 23 for guiding the optical film 13 to the winding core 11, and the optical film 13 wound on the winding core 11. Touch roller 25.

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 optical 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 optical film 13. Thereby, the traveling optical film 13 is guided to the core 11, the travel of the optical film 13 is reduced by the guide roller 23, and the optical film 13 can be smoothly supplied to the core 11. .

The touch roller 25 is a member that rotates following the rotation of the core 11. Accordingly, the optical film 13 wound around the core 11 can be pressed to prevent the wound optical film 13 from being separated from the core 11.

In the winding device 20 configured as described above, the optical 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 optical film 13 is wound around the core 11.

In the present invention, the winding process of winding the optical film 13 around the core 11 preferably includes a vibration winding process. In the vibration winding process, vibration is applied to change the relative positions of the optical film 13 and the core 11 in the width direction of the optical 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. However, the optical film 13 and the core 11 may be vibrated so that the relative position in the width direction of the film changes. 13 may be vibrated; both the optical film 13 and the core 11 may be vibrated.

FIG. 4 is a graph for explaining the vibration in the vibration winding process. The x-axis of the graph of FIG. 4 indicates the integrated thickness (mm) of the optical film being wound at the position of the optical film that is starting to be wound around the core. That is, the distance between the outermost surface of the wound optical film 13 and the surface of the core 11 is shown, and corresponds to the integrated thickness x of the optical film 13 in FIG. The y-axis of the graph of FIG. 4 indicates the distance between the center position in the width direction of the optical film 13 and the center position in the width direction of the core 11 (the distance between the centers of the optical 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 a sinusoidal vibration as shown by a curve 52 in FIG. 4; may be a square wave vibration as shown by a curve 53; Such vibration may be used. In particular, the vibration as shown by the curve 51 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 52 is a (x); a function indicating a rectangular wave vibration with an amplitude A and a period T as indicated by a curve 53 b (x); where f (x) is a function showing the vibration of amplitude A and period T as shown by the curve 51, 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 54 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 optical film. The x-axis in FIG. 5 indicates the position in the width direction of the roll body of the optical film; the y-axis indicates the integrated emboss height.

As shown in FIG. 5, when no vibration is applied, the graph is shown by a line 57; 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 a graph shown by a line 56; when it is vibrated so as to be a function f (x), it becomes a graph shown by a line 55.

When vibration is not applied, the embossed portion is laminated at the same position in the width direction of the film as indicated by a line 57. Therefore, 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 56, 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 become the function f (x), the stay time when the absolute value of the y displacement of the vibration is large becomes relatively long. Therefore, as shown by the line 55, the embossing on the roll body The overlapping of the parts can be effectively reduced. Thus, even if the roll body of the optical film wound up through the vibration winding process is stored for a long period of time, the occurrence of deformation can be sufficiently suppressed.

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) is satisfied; the function f (x) has a vibration period T and an integrated thickness of the optical film. The function may be a function that gradually decreases as x increases; the function f (x) may be such that the vibration amplitude A increases gradually as the integrated thickness x of the optical film increases. It may be a function.

Among these, from the viewpoint of obtaining a roll body of an optical film in which the occurrence of deformation is further suppressed, it is preferable to gradually increase the amplitude A of vibration as the integrated thickness of the optical 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 optical film is small and deformation of the roll body is difficult to occur, deformation of the roll body can be sufficiently suppressed even when vibration having a small amplitude is applied. On the other hand, if the integrated thickness of the wound optical film increases as the optical film is wound on the core, the roll body is likely to be deformed. Thus, when the integrated thickness of the wound optical film is large and deformation of the roll body is likely to occur, by applying vibration with a large amplitude, the overlap of the embossed portions can be effectively reduced, and the roll body It is thought that the deformation of can be further suppressed.

Further, it is preferable to gradually reduce the vibration period T as the integrated thickness of the optical film increases. If the period of vibration is small, it is considered that the load on the optical film can be reduced. And as an optical film is wound up, if the integrated thickness of the wound up optical film increases, the roll body is likely to be deformed. Thus, when the integrated thickness of the wound optical film is large and deformation of the roll body is likely to occur, the load on the optical film can be effectively reduced by applying vibration with a small period, and the roll It is considered that the occurrence of body deformation 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 less than a certain value, the side surfaces of both ends in the axial direction of the roll body do not wavy greatly, and the moving distance of the film per unit time does not increase excessively, so that an excessive increase in haze can be suppressed.

The period T of vibration is preferably 0.2 to 10% of the film width, and more preferably 0.3 to 6%. Specifically, it can be about 3 to 120 mm. When the period T is equal to or greater than a certain value, the side surfaces at both ends in the axial direction of the roll body do not wavy greatly, and the moving distance of the film per unit time does not increase excessively, so that an excessive increase in haze can be suppressed. 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. Examples of other winding processes include a process of winding without changing the center distance y (non-vibrating winding process). The non-vibrating winding process and the vibrating winding process can be arbitrarily combined.

For example, 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 integrated thickness of the optical film is small, and the roll body is hardly deformed, so that the non-vibrating winding process can be performed. On the other hand, as the winding of the optical film proceeds and the integrated thickness of the wound optical 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, when the non-vibrating winding process is performed at the end of winding, the optical film can be smoothly fed out when the optical film is fed out from the roll body. For example, if the end of winding is the vibration winding process, when the optical film starts to be unwound from the obtained roll body, it may not be smoothly unwound due to meandering of the optical film. On the other hand, by setting the end of winding as a non-vibrating winding process, the optical film can be smoothly fed out immediately after the optical film starts to be unwound from the roll body.

As described above, the roll body of the optical film of the present invention is a step of winding the optical film around the core while periodically vibrating at least one of the optical film and the core in the width direction of the film (vibration winding step). It is obtained through 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, the optical film of the present invention can suppress the deformation of the roll body even though the film thickness is very thin. By suppressing the deformation of the roll body, it is possible to suppress the deterioration of the optical characteristics due to the non-uniform tension applied to the optical film or the film thickness becoming non-uniform.

In particular, when the optical film contains an aliphatic polyester compound, the strength of the optical film is likely to decrease, and the roll body is likely 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.

Also, in the vibration winding process, the optical films; particularly, the embossed part and the optical film surface not provided with the embossed part tend to rub against each other, whereby the optical film surface not provided with the embossed part is easily damaged. On the other hand, since the optical film of this invention contains the compound represented by General formula (1), it can have favorable slipperiness. Thereby, even if the embossed portion and the optical film surface not provided with the embossed portion rub against each other, the optical film surface not provided with the embossed portion is hardly damaged and the increase in haze (external haze) is suppressed. Can do. As a result, the yield of the optical film or polarizing plate can be increased.

4). Polarizing plate The polarizing plate of the present invention includes a polarizer and two protective films sandwiching the polarizer.

<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>
At least one of the two protective films sandwiching the polarizer is preferably an optical film obtained from the roll body of the optical film of the present invention. The other of the two protective films may be another protective film.

Examples of other protective films include (meth) acrylic resin films, polyester films, cellulose ester films, and the like, preferably cellulose ester films. The cellulose ester contained in the cellulose ester film is defined in the same manner as the cellulose ester contained in the optical film described above, and may preferably be cellulose triacetate.

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 Rt 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 from 0 to 80 nm, and more preferably from 0 to 50 nm.

The thickness of the other 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 of bonding the optical film of the present invention 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. It is preferable to use an active energy ray-curable adhesive because the resulting adhesive layer has a high elastic modulus and can easily suppress dimensional changes of the polarizing plate.

The active energy ray-curable adhesive composition is a photo radical polymerization composition using photo radical polymerization, a photo cation polymerization composition using photo cation polymerization, or a hybrid type using both photo radical polymerization and photo cation polymerization. It can be a composition or the like.

A radical photopolymerizable composition is a composition comprising a radically polymerizable compound containing a polar group such as a hydroxy group or a carboxy group and a radically polymerizable compound not containing a polar group described in JP-A-2008-009329 in a specific ratio. It can be a thing. The radical polymerizable compound is preferably a compound having an ethylenically unsaturated bond capable of radical polymerization. Preferable examples of the compound having an ethylenically unsaturated bond capable of radical polymerization include a compound having a (meth) acryloyl group. Examples of the compound having a (meth) acryloyl group include an N-substituted (meth) acrylamide compound and a (meth) acrylate compound. (Meth) acrylamide means acrylamide or methacrylamide.

The cationic photopolymerization type composition comprises (α) a cationic polymerizable compound, (β) a cationic photopolymerization initiator, and (γ) light having a wavelength longer than 380 nm, as disclosed in Japanese Patent Application Laid-Open No. 2011-028234. It may be a composition containing each component of a photosensitizer exhibiting maximum absorption and (δ) naphthalene photosensitizer.

Such a polarizing plate is, for example, a step of subjecting the surface of the optical film to easy adhesion (corona treatment, plasma treatment, etc.); a step of applying an active energy ray-curable adhesive to at least one of the polarizer and the optical film; It can be manufactured through a step of bonding the polarizer and the optical film through the obtained adhesive layer; a step of curing the adhesive layer in a state where the polarizer and the optical film are bonded.

5. Liquid Crystal Display Device The liquid crystal display device of the present invention includes a first polarizing plate, a liquid crystal cell, a second polarizing plate, and a backlight in this order. At least one of the first and second polarizing plates may be the polarizing plate of the present invention. The polarizing plate of the present invention is preferably arranged so that the optical film of the present invention is on the liquid crystal cell side.

Specifically, the first polarizing plate includes a first polarizer, a protective film F1 disposed on a surface opposite to the liquid crystal cell of the first polarizer, and a liquid crystal cell of the first polarizer. And a protective film F2 disposed on the side surface. The second polarizing plate is disposed on the surface opposite to the liquid crystal cell of the second polarizer, the protective film F3 disposed on the liquid crystal cell side of the second polarizer, and the second polarizer. And a protective film F4. At least one of the protective films F1, F2, F3 and F4; preferably at least one of F2 and F3 is an optical film obtained from the roll body of the optical film of the present invention.

The liquid crystal display device of the present invention may be a medium or large-sized liquid crystal display device such as a television or a notebook computer; it may be a small liquid crystal display device such as a smartphone. Especially, since the effect of the present invention is easily obtained, the liquid crystal display device is a small-sized liquid crystal display device having a display area (not shown) having a diagonal length of 10 inches or less, preferably 5 inches or less. Is preferred.

FIG. 6 is a schematic diagram showing an example of a small liquid crystal display device. As shown in FIG. 6, the small liquid crystal display device 100 includes a liquid crystal cell 110, a first polarizing plate 130 and a second polarizing plate 150 sandwiching the liquid crystal cell 110, and a backlight 170; Cover glass 190 disposed on the viewing side surface of plate 130, touch panel unit 210 disposed between first polarizing plate 130 and liquid crystal cell 110, and rechargeable battery disposed on the back side of backlight 170 230.

The display mode of the liquid crystal cell 110 may be various display modes such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, FFS (Fringe Field Switching), and has a wide viewing angle. The IPS mode or the FFS mode is preferable.

The first polarizing plate 130 is disposed on the viewing side surface of the liquid crystal cell 110; the first polarizer 131 and the protective film disposed on the surface of the first polarizer 131 opposite to the liquid crystal cell 110. 133 (F1) and a protective film 135 (F2) disposed on the surface of the first polarizer 131 on the liquid crystal cell 110 side. The second polarizing plate 150 is disposed on the surface of the liquid crystal cell 110 on the backlight side; the second polarizer 151 and the protective film disposed on the surface of the second polarizer 151 on the liquid crystal cell 110 side. 153 (F3) and a protective film 155 (F4) disposed on the surface of the second polarizer 151 opposite to the liquid crystal cell 110. In FIG. 6, both of the protective films 135 (F2) and 153 (F3) can include an optical film obtained from the roll body of the present invention.

The touch panel unit 210 is disposed between the liquid crystal cell 110 and the first polarizing plate 130 (on-cell type). However, the arrangement of the touch panel unit 210 is not limited to the mode shown in FIG. 6, and the touch panel unit 210 may be provided integrally with the cover glass 190 (cover glass integrated type); (In-cell type).

The rechargeable battery 230 may be, for example, a lithium ion secondary battery.

As described above, both of the protective films 135 (F2) and 153 (F3) can include an optical film obtained from the roll body of the present invention. In the roll body of the present invention, the deformation of the roll body is suppressed even though the film thickness of the optical film is very thin. Therefore, by applying non-uniform tension to the optical film due to the deformation of the roll body, it is possible to suppress a decrease in display performance due to non-uniform retardation or non-uniform film thickness on the optical film. .

Also, a liquid crystal display device tends to become hot due to the heat of the backlight. In particular, a small liquid crystal display device as shown in FIG. 6 includes a rechargeable battery 230 that generates heat during charging and discharging, and the device volume is small. In this invention, the thermal durability of a film can be improved because the compound represented by General formula (1) further contains a sulfur atom. Thereby, even in a small-sized liquid crystal display device in which the temperature inside the device is 50 ° C. or higher, the protective films 135 (F2) and 153 (F3) have good durability and can maintain good display performance. In addition to the heat of the backlight and the charge / discharge heat, the compound represented by the general formula (1) contains a sulfur atom when used in a high temperature environment, thereby improving the durability of the film. It is preferable from a viewpoint which can be obtained.

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

1. Optical film materials <Cellulose ester>
Cellulose triacetate (acetyl group substitution degree: 2.85, weight average molecular weight Mw: 285000)

<Compound represented by the general formula (1)>

<Comparative compound>

<Polyester compound>

2. Production of Optical 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)
Using the obtained fine particle addition liquid, a dope liquid having the composition shown below was prepared. First, the following components were put into a sealed container, heated to 70 ° C., and the cellulose ester was completely dissolved while stirring. The obtained solution was used as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. Filtration using 244 gave a dope solution.
(Dope solution composition)
Cellulose ester (cellulose triacetate having an acetyl substitution degree of 2.85, Mw: 285000): 100 parts by mass Polyester compound K1: 15 parts by mass Compound 1-1 (compound represented by the general formula (1)): 1 part by mass Addition of fine particles Liquid: 0.2 parts by mass (solid content)
Methylene chloride: 475 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. Then, after drying the dope liquid on a support body to the range which can be peeled, it peeled from the stainless steel band support body, and obtained the film-form thing. The residual solvent amount of the dope at the time of peeling was 25%.

The obtained film-like material was dried at 120 ° C. while being stretched in the width direction (TD direction) at a stretch ratio of 1.01 with a tenter. Next, the width is released and dried at 120 ° C. while being conveyed by a number of rolls, and then subjected to a knurling process with a width of 10 mm and a height of 5 μm at both ends of the film to produce a film with a width of 1400 mm and a thickness of 20 μm. did.

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.

<Example 2>
The vibration condition of the vibration winding process is the same as that of Example 1 except that the condition (oscillate B) with a period T = 5 mm and an amplitude A = 8 mm satisfying the function f (x) represented by the curve 51 in FIG. 4 is changed. Thus, a roll body 102 of the film was obtained.

<Comparative Example 1>
A roll body 103 of the film was obtained in the same manner as in Example 1 except that the produced film was wound (straight) without vibrating the core.

<Comparative example 2>
A film was produced in the same manner as in Example 1 except that the compound represented by the general formula (1) was not added. And the roll body 104 of the film was obtained like Example 1 except having wound up the obtained film by the straight winding which does not vibrate a core.

<Comparative Example 3>
A roll body 105 was obtained in the same manner as in Example 1 except that the compound represented by the general formula (1) was not contained.

<Comparative example 4>
A film was produced in the same manner as in Example 1 except that the compound represented by the general formula (1) was not contained and the content of the silica particles as the matting agent was changed to 2% by mass. Obtained.

<Examples 3 to 6, Comparative Example 5>
A film was produced in the same manner as in Example 1 except that the film thickness of the obtained film was changed as shown in Table 4, and rolls 107 to 111 were obtained.

<Example 7>
A roll was produced in the same manner as in Example 1 except that the content of the polyester compound K1 was changed to 5 parts by mass.

<Examples 8 to 12, Comparative Example 6>
Rolls 113 to 118 were obtained in the same manner as in Example 4 except that the content of the compound represented by the general formula (1) was changed as shown in Table 4.

<Comparative Example 7>
A film was produced in the same manner as in Comparative Example 2 except that no polyester compound was contained, and a roll body 119 was obtained.

<Examples 13 to 25, Comparative Examples 8 to 9>
Rolls 120 to 134 were obtained in the same manner as in Example 1 except that the type of the compound represented by the general formula (1) was changed as shown in Table 5.

The production conditions for the films of Examples 1-12 and Comparative Examples 1-7 are shown in Table 4; the production conditions for the films of Examples 13-25 and Comparative Examples 8-9 are shown in Table 5.

The shape of the obtained roll body, the haze of the film, the phase difference and the thermal durability were evaluated by the following methods.

(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 a part of the roll surface. △: Wrinkles or dents are observed on the entire roll surface. Yes, wrinkles and dents are observed on the entire surface. XX: The roll surface has significant shape deterioration, wrinkles and dents are recognized on the entire surface, and the shape has deteriorated to the inside of the roll. It was judged that there was no problem.

(Haze)
A film was drawn out from the obtained roll body, cut out at 10 points and a size of 4 cm × 4 cm at equal intervals in the width direction, and conditioned at 23 ° C. and 55% RH, respectively. The haze of the obtained film was measured with a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.) according to JIS K-7136, and the average value of these 10 points was calculated. Asked.
◎: Haze value is 0.3% or less ○: Haze value is more than 0.3% and less than 0.4% △: Haze value is more than 0.4% and 0.5% or less ×: Haze value is more than 0.5% △ or more was judged to be a practically no problem level.

(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.

(Thermal durability)
A film was drawn out from the obtained roll body, cut out at 10 points and a size of 4 cm × 4 cm at equal intervals in the width direction, and the obtained film was stored in a thermostat at 50 ° C. for 2000 hours. The film after storage was conditioned at 23 ° C. and 55% RH, and then the haze was measured in the same manner as described above, and the average value of these 10 points was determined. And the haze value (average value) before preservation | save and the haze value (average value) after preservation | save were applied to the following formula, and the change rate of haze was computed.
Haze change ratio = (Haze after storage−Haze before storage) / (Haze before storage) × 100 (%)
◎: Haze change rate is less than 3% ○: Haze change rate is 3% or more and less than 5% △: Haze change rate is 5% or more and less than 15% ×: Haze change rate is 15% or more

Moreover, a polarizing plate was produced by the following method using the film obtained from the produced roll body, and the yield of the polarizing plate was evaluated.

(Yield of polarizing plate)
1) Production of polarizer 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.

2) Preparation of active energy ray-curable adhesive liquid The following components were mixed and then defoamed to prepare a radical polymerization type active energy ray-curable adhesive liquid.
(Composition of active energy ray-curable adhesive liquid)
Radical polymerizable compound 1: hydroxyethylacrylamide (HEAA, homopolymer Tg 123 ° C., manufactured by Kojin Co., Ltd.): 39.1% by mass
Radical polymerizable compound 2: Tripropylene glycol diacrylate (Aronix M-220, homopolymer Tg 69 ° C., manufactured by Toagosei Co., Ltd.): 19.0% by mass
Radical polymerizable compound 3: acryloylmorpholine (ACMO, homopolymer Tg 150 ° C., manufactured by Kojin Co., Ltd.): 39.1% by mass
Radical polymerization initiator 1: Diethylthioxanthone (KAYACURE DETX-S, manufactured by Nippon Kayaku Co., Ltd.): 1.4% by mass
Radical polymerization initiator 2: 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (IRGACURE907, manufactured by BASF): 1.4% by mass

3) Preparation of polarizing plate Two films (films obtained from the roll body of the same number) obtained from the roll body produced on the same manufacturing conditions were prepared, and each surface was subjected to corona discharge treatment. The conditions for the corona discharge treatment were a corona output intensity of 2.0 kW and a line speed of 18 m / min. Next, the active energy ray-curable adhesive liquid prepared above is applied to the corona discharge-treated surface of the film with a bar coater so that the film thickness after curing is about 3 μm. An adhesive layer was formed.

Subsequently, the produced polarizer was sandwiched between the two films to obtain a laminate of film / active energy ray curable adhesive layer / polarizer / active energy ray curable adhesive layer / film.

On one side of this laminate, ultraviolet light (gallium-filled metal halide lamp) was applied using an ultraviolet irradiation device with a belt conveyor (Fusion UV Systems, Inc. Light HAMMER10 bulb: V bulb, peak illuminance: 1600 mW / cm ² ). The active energy ray-curable adhesive layer was cured by irradiating with ultraviolet rays so that the integrated irradiation amount was 1000 / mJ / cm ² (wavelength 380 to 440 nm) to obtain a polarizing plate.

4) Evaluation The yield of the obtained polarizing plate was evaluated by the following method.
The surface of the polarizing plate was visually observed, and the transparency due to the flatness failure and haze was evaluated. The permeability due to the haze of the polarizing plate was confirmed by sensory evaluation for the presence or absence of fine scratches when the polarizing plate was placed on a white lamp. And the thing which does not have any problem in the transparency resulting from the flatness failure and the haze was defined as a non-defective product. The ratio of non-defective products and defective products when 50 polarizing plates were produced was calculated.
◎: Non-defective polarizing plate is 95% or more ○: Non-defective polarizing plate is 80% or more and less than 95% △: Non-defective polarizing plate is 60% or more and less than 80% ×: Non-defective polarizing plate is less than 60%

The evaluation results of Examples 1 to 12 and Comparative Examples 1 to 7 are shown in Table 6; the evaluation results of Examples 13 to 25 and Comparative Examples 8 to 9 are shown in Table 7.

As shown in Tables 6 and 7, it can be seen that in the roll bodies of Examples 1 to 25, deformation of the roll bodies is suppressed and haze is low.

On the other hand, in the roll body of Comparative Example 1, the roll body was deformed and the roll shape was poor. This is considered to be caused by wrinkles generated on the entire roll body because the roll diameter was increased at both ends in the width direction of the roll body because it was wound by the non-vibration winding method (straight winding). On the other hand, the roll bodies of Comparative Examples 3 and 4 were able to suppress deformation of the roll body, but the haze increased. This is presumably because the film slipping property is low, the films rub against each other, and the film surface is finely scratched. Since the film of Comparative Example 5 is very thin, it is considered that the deformation of the roll body could not be sufficiently suppressed. The film of Comparative Example 6 could not suppress the deformation of the roll body. This is presumably because the content of the compound represented by the general formula (1) is too large, so that the film becomes excessively slippery and winding deviation occurs. In addition, an increase in haze due to the crying out (precipitation) of the additive due to the large amount of additive added was observed.

From the comparison between Examples 1, 13, and 14 and Comparative Example 8, it can be seen that the haze of the film can be reduced by setting the carbon number of the alkyl group of R ₁ and R _{2 in} the general formula (1) to 8 or more. Further, from the comparison between Example 13 and Example 15, by making the alkyl group of R ₁ and R _{2 in} the general formula (1) linear, the haze of the film is reduced rather than being branched. I can understand. Moreover, it turns out that compatibility with a cellulose ester can improve and internal haze can be reduced because L of General formula (1) contains a carbonyl group from contrast of Example 24 and Comparative Example 9. Further, from comparison of Examples 16 to Example 23, the general formula both R ₁ and R ₂ (1) With an alkyl group, rather than one hydrogen atom, it can reduce the haze of the film I understand.

Moreover, the film obtained from the roll body of the comparative example 2 containing an aliphatic polyester compound from the contrast of the comparative example 2 and the comparative example 7 is from the film obtained from the roll body of the comparative example 7 which does not contain an aliphatic polyester compound. It is also shown that the roll body is significantly deformed when straight winding is performed. From this, it is suggested by applying this invention that even if it is a film containing an aliphatic polyester compound, the deformation | transformation of a roll body can be suppressed favorably.

Further, an optical film and its roll were obtained in the same manner as in Comparative Example 1 except that the film thickness of the optical film was 50 μm. And as a result of evaluating the shape of the obtained roll body similarly to the above-mentioned, it is "(circle)" and the deformation | transformation of the roll body hardly occurred. From this, it is suggested that the “deformation of the roll body” which is the subject of the present invention is remarkably generated when the film thickness is thinner than 50 μm.

This application claims priority based on Japanese Patent Application No. 2014-047539 filed on Mar. 11, 2014. The contents described in the application specification and the drawings are all incorporated herein.

According to the present invention, it is possible to provide a roll body of an optical film in which deformation of the roll body is suppressed and an increase in haze is suppressed.

DESCRIPTION OF SYMBOLS 10 Roll body 11 Winding core 13 Optical film 13A Embossing part 20 Winding device 21 Vibration control device 23 Guide roller 25 Touch roller 100 Small liquid crystal display device 110 Liquid crystal cell 130 First polarizing plate 131 First polarizer 133, 135, 153, 155 Protective film 150 Second polarizing plate 151 Second polarizer 170 Backlight 190 Cover glass 210 Touch panel 230 Rechargeable battery

Claims (13)

A roll of optical film obtained by winding an optical film having a thickness of 15 to 45 μm having embossed portions at both ends in the width direction in the longitudinal direction of the film,
The optical film includes a cellulose ester and 0.05 to 5 parts by mass of a compound represented by the following general formula (1) with respect to 100 parts by mass of the cellulose ester,

(In general formula (1),
L is an ester bond, an amide bond, a carbonyl group, or one or more selected from the group consisting of an ester bond, an amide bond or a carbonyl group and an alkylene group, a nitrogen atom, an oxygen atom, a sulfur atom, a zinc atom, a calcium atom, and a magnesium atom. Represents a divalent group in combination with;
R ₁ represents an alkyl group having 8 to 26 carbon atoms, or an alkenyl group having 8 to 26 carbon atoms;
R ₂ represents a hydrogen atom, an alkyl group having 8 to 26 carbon atoms, or an alkenyl group having 8 to 26 carbon atoms)
The roll body of the optical film in which the side surface shape of the axial direction both ends of the said roll body is wavy. L in the general formula (1) is
-C (= O) -O-, -C (= O) NH-,
—C (═O) —O—R ₃ —O—C (═O) —, —C (═O) —NH—R ₃ —NH—C (═O) — (R ₃ is a group having 1 to 5 alkylene groups),
-C (= O) -OMO-C (= O)-(M is a zinc atom, a calcium atom or a magnesium atom),
—C (═O) —R ₄ —O—R ₄ —C (═O) —, —C (═O) —R ₄ —SR ₄ —C (═O) —, —C (═O) —R ₄ —NH—R ₄ —C (═O) — (R ₄ is an alkylene group having 1 to 5 carbon atoms), and —C (═O) —R ₅ —C (═O) — (R ₅ The roll body for an optical film according to claim 1, wherein is a group selected from the group consisting of an alkylene group having 1 to 5 carbon atoms. R ₁ and R _{2 in} the general formula (1) are each independently a linear alkyl group having 8 to 26 carbon atoms, or a linear alkenyl group having 8 to 26 carbon atoms. The roll body of the optical film according to claim 1. The roll of the optical film according to claim 1, wherein L in the general formula (1) contains a sulfur atom. The roll of optical film according to claim 1, wherein the optical film further comprises an aliphatic polyester compound obtained by polycondensation of an aliphatic diol and an aliphatic dicarboxylic acid. The retardation of the optical film defined by the following formula (I) and measured in the in-plane direction measured at a measurement wavelength of 590 nm is Ro (590), defined by the following formula (II) and measured at a measurement wavelength of 590 nm. The roll body of an optical film according to claim 1, wherein Rro (590) | ≦ 5 nm and | Rth (590) | ≦ 5 nm are satisfied, where Rth (590) is a retardation in the thickness direction.
Formula (I) Ro = (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) The thickness of the cellulose ester is 0.05 to 5 parts by mass with respect to 100 parts by mass of the cellulose ester and the compound represented by the following general formula (1) is provided. Preparing a 45 μm long optical film;

(In general formula (1),
L is an ester bond, an amide bond, a carbonyl group, or one or more selected from the group consisting of an ester bond, an amide bond or a carbonyl group and an alkylene group, a nitrogen atom, an oxygen atom, a sulfur atom, a zinc atom, a calcium atom, and a magnesium atom. Represents a divalent group in combination with;
R ₁ represents an alkyl group having 8 to 26 carbon atoms or an alkenyl group having 8 to 26 carbon atoms;
R ₂ represents a hydrogen atom, an alkyl group having 8 to 26 carbon atoms, or an alkenyl group having 8 to 26 carbon atoms)
Winding the optical film into a roll around a core,
The winding step includes a step of winding the optical film around the core while periodically vibrating at least one of the optical film and the core in the width direction of the optical film. Body manufacturing method. A polarizing plate comprising an optical film obtained from the roll body according to claim 1. A liquid crystal display device comprising an optical film obtained from the roll body according to claim 1. Including the first polarizing plate, the liquid crystal cell, the second polarizing plate, and the backlight in this order,
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 according to claim 9, wherein at least one of the protective films F2 and F3 includes the optical film. The liquid crystal display device according to claim 10, wherein the liquid crystal cell is an IPS mode or FFS mode liquid crystal cell. The liquid crystal display device according to claim 9, wherein the diagonal length of the display area is 10 inches or less. The liquid crystal display device according to claim 12, further comprising a rechargeable battery.

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