JP6136226B2 - Optical film roll body and manufacturing method thereof, packaging body, polarizing plate, and liquid crystal display device - Google Patents

Description

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

  In recent years, liquid crystal display devices are required to be thin. A liquid crystal display device usually has a liquid crystal cell, a pair of polarizing plates sandwiching the liquid crystal cell, and a backlight. The polarizing plate has a polarizer and a pair of protective films that sandwich the polarizer. Therefore, with the thinning of the liquid crystal display device, the protective film that is a constituent member is also required to be further thinned.

  As the protective film, a cellulose ester film (for example, Patent Document 1), a laminated film of cellulose ester layer / (meth) acrylic resin layer / cellulose ester layer (for example, Patent Document 2), and the like have been proposed.

  Such a protective film is normally preserve | saved as a roll body wound up in the length direction. Therefore, in order to suppress the sticking between the protective films while the roll body of the protective film is stored, the both ends of the protective film in the width direction are usually embossed (for example, Patent Documents). 3 and 4).

JP 2011-127046 A JP 2011-236259 A JP 2002-122741 A JP 2011-16323 A

  These protective films are bonded to a polarizer via an adhesive to form a polarizing plate. As the adhesive used for bonding, an active energy ray-curable adhesive may be used. Therefore, in order to uniformly form the active energy ray-curable adhesive, the protective film is required to have a certain affinity with the active energy ray-curable adhesive.

  As such a protective film, the (meth) acrylic resin layer / cellulose ester layer / (meth) acrylic resin layer laminated film has a relatively high affinity for the active energy ray-curable adhesive of the (meth) acrylic resin layer. It is considered effective because it is expensive. However, since such a laminated film includes a (meth) acrylic resin layer having a low hardness on the surface, the strength of the embossed portion tends to be low. For this reason, there is a problem that the embossed portion tends to be crushed when the laminated film is rolled up.

  When the embossed portion of the protective film is crushed, the protective films laminated in the roll body are easily attached to each other. Thereby, the additive contained in the protective film easily oozes out on the surface of the protective film. As a result, when applying, for example, an active energy ray-curable adhesive or a hard coat layer solution to the surface of the protective film, uneven coating may occur. Such collapse of the embossed portion was particularly likely to occur in a protective film having a small thickness.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical film having few work defects and good workability even when the thickness is small.

［２］ 前記セルロースエステルのアシル基の総置換度が、２．１以上２．９５以下である、［１］に記載の光学フィルムのロール体。
［３］ 前記基材層は、ＳＰ値が９〜１４の添加剤をさらに含有する、［１］または［２］に記載の光学フィルムのロール体。
［４］ 前記添加剤が、ジオールとジカルボン酸との重縮合物由来の繰り返し単位を有するポリエステル化合物である、［１］〜［３］のいずれかに記載の光学フィルムのロール体。
［５］ 前記ポリエステル化合物は、炭素数２〜４の脂肪族ジオールと、芳香族ジカルボン酸を含有するジカルボン酸との重縮合物、または前記重縮合物の分子末端をアセチル基で封止した封止物である、［４］に記載の光学フィルムのロール体。
［６］ 前記添加剤の前記基材層における含有量が、前記セルロースエステルに対して１〜２０質量％である、［３］〜［５］のいずれかに記載の光学フィルムのロール体。
［７］ 前記基材層の厚みが、前記光学フィルムの総厚みの３０〜９０％の範囲内である、［１］〜［６］のいずれかに記載の光学フィルムのロール体。
［８］ 前記光学フィルムは、前記基材層と、前記基材層の両面に配置された２つの表層とを含む、［１］〜［７］のいずれかに記載の光学フィルムのロール体。
［９］ 前記光学フィルムの巻長が、１５００ｍ以上８０００ｍ以下である、［１］〜［８］のいずれかに記載の光学フィルムのロール体。 [1] A base material layer containing cellulose ester as a main component, and a (meth) acrylic resin having a number average molecular weight of 50,000 to 1,000,000 as a main component, disposed on at least one surface of the base material layer. A roll body of an optical film obtained by winding an optical film having a thickness of 10 to 50 μm including a surface layer in a direction perpendicular to the width direction of the film, wherein both end portions in the width direction of the surface layer of the optical film are The height of the convex part of the embossed part measured in a state where an initial load of 10 g is applied to a circular area of 5 mm in diameter on the surface of the embossed part is D ₀ , and the diameter is 5 mm. When the height of the convex part of the embossed part measured with the 1 kg load applied is D after being stored for 10 minutes at 23 ° C. and 55% RH with a 1 kg load applied to the circular area. The following formula The roll body of an optical film whose crushing resistance is 40% or more.

[2] The roll of the optical film according to [1], wherein the total substitution degree of the acyl group of the cellulose ester is 2.1 or more and 2.95 or less.
[3] The roll of optical film according to [1] or [2], wherein the base material layer further contains an additive having an SP value of 9 to 14.
[4] The roll body of an optical film according to any one of [1] to [3], wherein the additive is a polyester compound having a repeating unit derived from a polycondensate of diol and dicarboxylic acid.
[5] The polyester compound is a polycondensation product of an aliphatic diol having 2 to 4 carbon atoms and a dicarboxylic acid containing an aromatic dicarboxylic acid, or a molecular end of the polycondensate sealed with an acetyl group. The roll of optical film according to [4], which is a stationary object.
[6] The roll of the optical film according to any one of [3] to [5], wherein the content of the additive in the base material layer is 1 to 20% by mass with respect to the cellulose ester.
[7] The roll body of the optical film according to any one of [1] to [6], wherein the thickness of the base material layer is in the range of 30 to 90% of the total thickness of the optical film.
[8] The roll of optical film according to any one of [1] to [7], wherein the optical film includes the base material layer and two surface layers disposed on both surfaces of the base material layer.
[9] The roll body of the optical film according to any one of [1] to [8], wherein the winding length of the optical film is 1500 m or more and 8000 m or less.

[10] A method for producing a roll of an optical film according to any one of [1] to [9], wherein the substrate layer dope containing a cellulose ester and an organic solvent, and (meth) acrylic A step of preparing a surface layer dope containing a resin and an organic solvent, and a step of casting the base layer layer dope and the surface layer dope while being laminated simultaneously or sequentially on a casting support; Removing the organic solvent contained in the laminated base layer dope and the surface layer dope to obtain a laminate, stretching the laminate, base layer, and base layer An optical film roll comprising: a step of obtaining an optical film comprising a surface layer disposed on at least one surface of the optical film; and a step of forming embossed portions at both ends in the width direction on the surface layer of the optical film. Production method.
[11] The method for producing a roll of an optical film according to [10], wherein the stretching of the laminate is performed at a draw ratio of 1.05 to 1.5 times in a width direction of the laminate.
[12] The method for producing a roll body of an optical film according to [10] or [11], wherein the stretching of the laminate is performed at a draw ratio of 1.01 to 1.5 times in a transport direction of the laminate.
[13] The method for producing a roll body of an optical film according to any one of [10] to [12], wherein a transport speed of the laminate is 60 to 200 m / min.
[14] A polarizing plate comprising a polarizer and an optical film that is disposed on at least one surface of the polarizer and is cut out from the roll of the optical film according to any one of [1] to [9].
[15] The polarizing plate according to [14], wherein the polarizer and the optical film are bonded via an active energy ray-curable adhesive layer.
[16] A liquid crystal display device comprising a liquid crystal cell and the polarizing plate according to [14] or [15], which is disposed on at least one surface of the liquid crystal cell.
[17] A package comprising the roll of the optical film according to any one of [1] to [9] and a moisture-proof sheet for packaging the roll.

  According to the present invention, it is possible to provide an optical film having few work defects and good workability even when the thickness is small.

It is a schematic diagram which shows an example of the roll body of an optical film. It is a fragmentary perspective view which shows an example of the embossed part vicinity of an optical film. It is a fragmentary perspective view which shows an example of the embossing part in the measurement of a crushing resistance. It is a schematic diagram which shows an example of the measuring method of the crushing rate of the convex part of an embossed part. It is a perspective view which shows an example of the external appearance of a package body. It is sectional drawing of the package of FIG. 5A. It is a schematic diagram which shows an example of an embossing apparatus. It is a schematic diagram which shows an example of a structure of a liquid crystal display device.

1. Optical film An optical film contains the base material layer which contains a cellulose ester as a main component, and the surface layer which is arrange | positioned on the at least one surface and contains a (meth) acrylic resin as a main component.

Base material layer The base material layer contains a cellulose ester as a main component, and may further contain other components such as additives as necessary.

  The cellulose ester is a compound obtained by esterifying a hydroxyl group of cellulose with an aliphatic carboxylic acid or an aromatic carboxylic acid. That is, the acyl group contained in the cellulose ester is an aliphatic acyl group or an aromatic acyl group, preferably an aliphatic acyl group. The number of carbon atoms of the aliphatic acyl group is preferably 2 to 7 and more preferably 2 to 4 in order to obtain a certain or greater retardation. Examples of the aliphatic acyl group include an acetyl group, a propionyl group, a butanoyl group, and the like, and preferably an acetyl group.

The total substitution degree of the acyl group of the cellulose ester may be 2.0 or more and 3.0 or less. When the total substitution degree of the acyl group is “Dall”, the substitution degree of the acyl group having 2 carbon atoms is “D2”, and the substitution degree of the acyl group having 3 to 7 carbon atoms is “D3”, the retardation of the optical film Since expression is good, it is preferable to satisfy the following formulas simultaneously.
Formula (i) 2.0 ≦ Dall ≦ 3.0
Formula (ii) 1.5 ≦ D2 ≦ 3.0
Formula (iii) 0.0 ≦ D3 ≦ 0.7

  The total substitution degree Dall of the acyl group of the cellulose ester is preferably 2.1 or more, more preferably 2.3 or more, because it is highly soluble in a solvent and relatively easy to form a film. Preferably it is 2.5 or more, Most preferably, it is 2.8 or more. The total substitution degree of the acyl group is preferably 2.95 or less.

  Examples of the cellulose ester include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, and the like, preferably cellulose acetate. In the cellulose acetate, all of the acyl groups are preferably acetyl groups, and the degree of acetyl group substitution is more preferably 2.1 or more and 2.95 or less.

  The measuring method of the total substitution degree (acetyl group substitution degree) of an acyl group can be measured according to ASTM-D817-96.

The weight average molecular weight of the cellulose ester is preferably 7.5 × 10 ⁴ or more in order to improve the adhesion between the base material layer containing the cellulose ester and the surface layer containing the (meth) acrylic resin as a main component. 7.5 × 10 ⁴ or more and 3.0 × 10 ⁵ or less is more preferable, 1.0 × 10 ⁵ or more and 2.4 × 10 ⁵ or less is more preferable, and 1.6 × 10 ⁵ or more is preferable. It is particularly preferable that it is 2.4 × 10 ⁵ or less.

  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 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 Corp.) 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.

  Cellulose esters can be synthesized by a known method, for example, cellulose can be synthesized by esterifying a cellulose and an organic acid having 2 or more carbon atoms containing at least acetic acid or acetic anhydride (Japanese Patent Laid-Open No. Hei 10-2010). (See the method described in Japanese Patent No. 45804).

  Examples of cellulose that is a raw material for cellulose esters include cotton linters, wood pulp (derived from coniferous trees, derived from hardwoods), kenaf and the like. Only one type of cellulose as a raw material may be used, or two or more types may be combined. Commercially available cellulose esters include L20, L30, L40, and L50 manufactured by Daicel Corporation, Ca398-3, Ca398-6, Ca398-10, Ca398-30, and Ca394-60S manufactured by Eastman Chemical Japan Co., Ltd. Is mentioned.

  The content of the cellulose ester in the base material layer is preferably 50% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more.

  The base material layer is further provided with a small amount of (meth) acrylic resin as necessary in order to increase adhesion with a surface layer containing a (meth) acrylic resin as a main component, which will be described later, or to reduce the hardness difference. You may contain.

Additives The base material layer may be a polyester compound, a sugar ester compound, a polyhydric alcohol ester compound, a polyvalent carboxylic acid ester compound (including a phthalic acid ester compound), a glycolate compound, and an ester compound (fatty acid ester compound) as necessary. And additives such as phosphate ester compounds). These additives can also function as plasticizers. Among these, a polyester compound is preferable from the viewpoints of enhancing the stretchability of the film so that the film can be stretched at a high magnification, the tear strength of the stretched film is easily increased, or a film having a low haze is easily obtained.

Polyester compound The polyester compound contains a repeating unit derived from a condensate of a dicarboxylic acid and a diol. The dicarboxylic acid constituting the polyester compound can be an aliphatic dicarboxylic acid, an alicyclic dicarboxylic acid, or an aromatic dicarboxylic acid. Carbon number of aliphatic dicarboxylic acid becomes like this. Preferably it is 4-20, More preferably, it is 4-12. 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.

  Carbon number of aromatic dicarboxylic acid becomes like this. Preferably it is 8-20, More preferably, it is 8-12. Examples of aromatic dicarboxylic acids include 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid (isophthalic acid), 1,4-benzenedicarboxylic acid (terephthalic acid), 1,5-naphthalene Dicarboxylic acid, 1,4-xylidene dicarboxylic acid and the like are included, and 1,4-benzenedicarboxylic acid (terephthalic acid) is preferable.

  Carbon number of alicyclic dicarboxylic acid becomes like this. Preferably it is 6-20, More preferably, it is 6-12. Examples of the alicyclic dicarboxylic acid include 1,3-cyclobutane dicarboxylic acid, 1,3-cyclopentane dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, 1,4-cyclohexane diacetic acid and the like.

  The dicarboxylic acid constituting the polyester compound may be one type or two or more types. The dicarboxylic acid constituting the polyester compound preferably contains an aromatic dicarboxylic acid in order to increase the SP value and the compatibility with the cellulose ester.

  The diol constituting the polyester compound can be an aliphatic diol, an alkyl ether diol, an alicyclic diol, or an aromatic diol. The carbon number of the aliphatic diol is preferably 2 to 20, more preferably 2 to 12, and still more preferably 2 to 4. Examples of aliphatic diols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl- 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propane Diol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl-1,5-pentanediol, 1, 6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1 , 10-decanediol, and 1,12 -Octadecanediol and the like are included. Carbon number of alkyl ether diol becomes like this. Preferably it is 4-20, More preferably, it is 4-12. Examples of the alkyl ether diol include polytetramethylene ether glycol, polyethylene ether glycol and polypropylene ether glycol.

  Carbon number of alicyclic diol becomes like this. Preferably it is 4-20, More preferably, it is 4-12. Examples of the alicyclic diol include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and the like.

  The carbon number of the aromatic diol is preferably 6-20, more preferably 6-12. Examples of aromatic diols include 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), 1,4-dihydroxybenzene (hydroquinone), and the like.

  The diol constituting the polyester compound may be one type or two or more types. The diol constituting the polyester compound preferably contains an aliphatic diol.

  The polyester compound is a condensate of a dicarboxylic acid containing an aromatic dicarboxylic acid and an aliphatic diol (preferably an aliphatic diol having 2 to 4 carbon atoms) because the stretchability and transparency of the resulting film are good. It is preferable that the repeating unit derived from is included.

  The molecular terminal of the polyester compound may be sealed with a monocarboxylic acid or a monoalcohol as necessary.

  The monocarboxylic acid can be an aliphatic monocarboxylic acid, an alicyclic monocarboxylic acid or an aromatic monocarboxylic acid. The carbon number of the aliphatic monocarboxylic acid may be preferably 2-30, more preferably 2-4. Examples of the aliphatic carboxylic acid include acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid and the like. Examples of the alicyclic monocarboxylic acid include cyclohexyl monocarboxylic acid. Examples of aromatic monocarboxylic acids include benzoic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethyl benzoic acid, ethyl benzoic acid, normal propyl benzoic acid, aminobenzoic acid, acetoxybenzoic acid, Phenylacetic acid, 3-phenylpropionic acid and the like are included.

  The monoalcohol can be an aliphatic monoalcohol, an alicyclic monoalcohol, or an aromatic monoalcohol. The aliphatic monoalcohol has 1 to 30 carbon atoms, preferably 1 to 3 carbon atoms. Examples of aliphatic monoalcohols are methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, octanol, isooctanol, 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol Tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, dodecaoctanol, allyl alcohol, oleyl alcohol and the like. Examples of the alicyclic monoalcohol include cyclohexyl alcohol and the like. Examples of the aromatic monoalcohol include benzyl alcohol and 3-phenylpropanol.

  Among these, a polyester compound having a molecular end sealed with an aliphatic monocarboxylic acid (preferably acetic acid) is preferable.

Specific examples of the polyester compound having a ring structure include the following. In Table 1 described later, TPA: terephthalic acid, PA: phthalic acid, SA: succinic acid, AA: adipic acid, SEA: sebacic acid are shown.

The sugar ester compound is preferably a compound represented by the following formula (FA).

R _{1 to} R _{8 in} Formula (FA) represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group. R _{1 to} R ₈ may be the same as or different from each other.

  The substituted or unsubstituted alkylcarbonyl group is preferably a substituted or unsubstituted alkylcarbonyl group having 2 or more carbon atoms. Examples of the substituted or unsubstituted alkylcarbonyl group include a methylcarbonyl group (acetyl group) and an ethylcarbonyl group. Examples of the substituent that the alkyl group has include an aryl group such as a phenyl group.

  The substituted or unsubstituted arylcarbonyl group is preferably a substituted or unsubstituted arylcarbonyl group having 7 or more carbon atoms. Examples of the arylcarbonyl group include a phenylcarbonyl group. Examples of the substituent that the aryl group has include an alkyl group such as a methyl group.

Specific examples of the compound represented by the formula (FA) include the following. R in the table represents R _{1 to} R ₈ in the formula (FA).

Specific examples of the polyhydric alcohol ester compound are shown below. Examples of the divalent alcohol ester compound include the following.

Examples of the trivalent or higher alcohol ester compound include the following compounds.

  The polyvalent carboxylic acid ester compound is an ester compound of a divalent or higher, preferably 2-20 valent polycarboxylic acid and an alcohol compound. The polyvalent carboxylic acid is preferably a 2-20 valent aliphatic polyvalent carboxylic acid, or a 3-20 valent aromatic polyvalent carboxylic acid or a 3-20 valent alicyclic polyvalent carboxylic acid. .

  Examples of polyvalent carboxylic acids include trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid Contains aliphatic polycarboxylic acids such as fumaric acid, maleic acid, and tetrahydrophthalic acid, and oxypolycarboxylic acids such as tartaric acid, tartronic acid, malic acid, and citric acid, and suppresses volatilization from the film. For this, oxypolycarboxylic acids are preferred.

  Examples of the alcohol compound include an aliphatic saturated alcohol compound having a straight chain or a side chain, an aliphatic unsaturated alcohol compound having a straight chain or a side chain, an alicyclic alcohol compound, or an aromatic alcohol compound. Carbon number of an aliphatic saturated alcohol compound or an aliphatic unsaturated alcohol compound becomes like this. Preferably it is 1-32, More preferably, it is 1-20, More preferably, it is 1-10. Examples of the alicyclic alcohol compound include cyclopentanol, cyclohexanol and the like. Examples of the aromatic alcohol compound include benzyl alcohol and cinnamyl alcohol.

  Although there is no restriction | limiting in particular in the molecular weight of a polyhydric carboxylic acid ester compound, It is preferable that it is 300-1000, and it is more preferable that it is 350-750. The molecular weight of the polyvalent carboxylic acid ester plasticizer is preferably larger from the viewpoint of suppressing bleed-out; it is preferably smaller from the viewpoint of moisture permeability and compatibility with the cellulose ester.

  Examples of polyvalent carboxylic acid ester compounds include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate Rate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, tetrabutyl pyromellitic acid and the like.

  The polyvalent carboxylic acid ester compound may be a phthalic acid ester compound. Examples of the phthalate compound include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, dicyclohexyl terephthalate and the like.

  Examples of glycolate compounds include alkylphthalyl alkyl glycolates. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl Glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ethyl Glycolate and the like, preferably ethyl phthalyl ethyl glycolate.

  The ester compound includes a fatty acid ester compound, a citrate ester compound, a phosphate ester compound, and the like.

  Examples of the fatty acid ester compound include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate. Examples of the citrate ester compound include acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate. Examples of the phosphate ester compound include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc., preferably triphenyl phosphate .

  These additives may be used alone or in combination of two or more.

  As described above, when the films laminated in the roll body stick to each other, the additive contained in the base material layer may permeate the surface layer and ooze out on the surface of the film. In order to suppress the exudation of such an additive, the compatibility of the additive with the cellulose ester which is the main component of the base material layer is increased, and the (meth) acrylic resin which is the main component of the surface layer is used. It is considered effective to lower the compatibility. Therefore, it is preferable that the solubility parameter (SP value) of Fedors of the additive is in a range close to that of the cellulose ester. Specifically, the SP value of the additive is preferably in the range of 9 to 14, more preferably in the range of 9 to 13, and further preferably in the range of 9 to 12. The SP value of the cellulose ester varies depending on the degree of substitution and the like, but is usually about 11 to 13; the SP value of triacetyl cellulose is about 11.5.

  The absolute value of the difference between the SP values of the cellulose ester and the additive can be, for example, 2.5 or less, preferably 1.0 or less. The absolute value of the difference in SP value between the (meth) acrylic resin and the additive can be, for example, 4.0 or more, preferably 5.0 or more.

The SP value in the present invention can be obtained by calculation using the Fedors parameter. The unit of SP value is the square root of the value obtained by dividing the cohesive energy density ΔE by the molar volume V, and “(cm ³ / cal) ^1/2 ” can be used. The parameters of Fedors are described in References: Basic Science of Coatings by Yuji Harada, Kashiwa Shoten (1977), p54-57.

  The content of the additive in the base material layer is preferably 1 to 20% by mass and more preferably 1.5 to 15% by mass with respect to the cellulose ester. If the content of the additive is less than 1% by mass, the effect of imparting plasticity may not be sufficient. On the other hand, when the content of the additive is more than 20% by mass, the additive easily leaks out from the optical film.

  The base material layer may further contain an ultraviolet absorber, a retardation adjusting agent, a deterioration preventing agent and the like as necessary.

Ultraviolet Absorber As the ultraviolet absorber, a compound that is excellent in the ability to absorb ultraviolet light having a wavelength of 370 nm or less and that has good liquid crystal display properties and that absorbs less visible light having a wavelength of 400 nm or more is preferably used. Examples of ultraviolet absorbers include hindered phenol compounds, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like.

Specific examples of the ultraviolet absorber include the following UV-1 to UV-3.

  The content of the ultraviolet absorber is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the cellulose ester.

Surface layer The surface layer contains a (meth) acrylic resin as a main component, and may further contain other components as necessary.

(Meth) acrylic resin The (meth) acrylic resin is preferably a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and another copolymer component. In order to obtain, for example, a film having a small photoelastic coefficient, the content ratio of the methyl methacrylate-derived structural unit in the (meth) acrylic resin is preferably 50 to 99% by mass, and 60 to 95% by mass. Is more preferable.

  Examples of copolymerized components copolymerized with methyl methacrylate include alkyl methacrylates having 2 to 18 carbon atoms in the alkyl group; alkyl acrylates having 1 to 18 carbon atoms in the alkyl group; α, such as acrylic acid and methacrylic acid; β-unsaturated acids; unsaturated group-containing dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; aromatic vinyl compounds such as styrene and α-methylstyrene; α, β-unsaturated compounds such as acrylonitrile and methacrylonitrile; Saturated nitrile; maleic anhydride; maleimide; N-substituted maleimide; glutaric anhydride; acrylamide derivatives such as acryloylmorpholine (ACMO). These can be used alone or in combination of two or more monomers as a copolymerization component.

  Among these copolymer components, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, etc. are used from the viewpoint of improving the thermal decomposition resistance and fluidity of the copolymer. Alkyl acrylate; alkyl (meth) acrylate having a hydroxyl group such as methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate is preferred. In order to enhance the compatibility with the cellulose ester, acryloylmorpholine and the like are also preferable.

  In order to obtain an optical film with little variation in optical performance due to environmental conditions such as heat and humidity, the copolymer component that constitutes the (meth) acrylic resin contains an alicyclic alkyl group, or by intramolecular cyclization. A compound that forms a cyclic structure in the molecular main chain is preferred. Examples of the (meth) acrylic resin having a cyclic structure in the molecular main chain include a lactone ring-containing (meth) acrylic resin.

The resin composition and synthesis method of the lactone ring-containing (meth) acrylic resin are described in, for example, Japanese Patent Application Laid-Open Nos. 2012-0666538 and 2006-171464. The lactone ring structure contained in the (meth) acrylic resin is preferably represented by the following formula (1).

In Formula (1), R < ¹ > -R < ³ > shows a hydrogen atom or a C1-C20 organic residue each independently. The organic residue may contain an oxygen atom. Examples of organic residues include linear or branched alkyl groups, linear or branched alkylene groups, aryl groups, -OAc groups (Ac is an acetyl group), -CN groups, and the like. The lactone ring structure represented by the formula (1) is derived from an alkyl (meth) acrylate having a hydroxyl group described later.

The (meth) acrylic resin containing a lactone ring structure further includes a structural unit derived from an alkyl (meth) acrylate having 1 to 18 carbon atoms in the alkyl portion, and if necessary, a monomer containing a hydroxyl group, an unsaturated carboxylic acid A structural unit derived from an acid, a monomer represented by the general formula (2), or the like may be further included. R4 in the general formula (2) represents a hydrogen atom or a methyl group. X is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, -OAc group (Ac: acetyl group), -CN group, acyl group or -C-OR group (R is a hydrogen atom or 1 to carbon atoms) 20 organic residues).

  The content ratio of the lactone ring structure represented by the formula (1) in the (meth) acrylic resin containing a lactone ring structure is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, More preferably, it is 15-70 mass%. When the content of the lactone ring structure is more than 90% by mass, the molding processability is low, and the flexibility of the obtained film tends to be low. When the content of the lactone ring structure is less than 5% by mass, it is difficult to obtain a film having a necessary retardation, and heat resistance, solvent resistance, and surface hardness may not be sufficient.

  The content ratio of the structural unit derived from alkyl (meth) acrylate in the (meth) acrylic resin containing a lactone ring structure is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, Preferably it is 30-85 mass%.

  In the (meth) acrylic resin containing a lactone ring structure, the content ratio of the structural unit derived from the hydroxyl group-containing monomer, the unsaturated carboxylic acid or the monomer represented by the general formula (2) is preferably preferably 0 to 30. It is mass%, More preferably, it is 0-20 mass%, More preferably, it is 0-10 mass%.

  The (meth) acrylic resin containing a lactone ring structure has a hydroxyl group and an ester group in the molecular chain by polymerizing at least an alkyl (meth) acrylate having a hydroxyl group and another alkyl (meth) acrylate. A step of obtaining a polymer can be produced through a step of introducing a lactone ring structure by heat-treating the obtained polymer to intramolecular cyclization.

  The weight average molecular weight (Mw) of the (meth) acrylic resin can reduce the content of the organic solvent in the dope when the optical film is produced by the solution casting method, and the surface state of the obtained film-like product is good. In view of the above, it is preferably 50,000 or more, more preferably 80,000 or more. Moreover, in order to make it melt | dissolve uniformly with an organic solvent, an additive, etc., it is preferable that the weight average molecular weight (Mw) of a (meth) acrylic resin is 1 million or less.

  The weight average molecular weight of the (meth) acrylic resin can be measured by gel permeation chromatography.

  (Meth) acrylic resin is, for example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electrochemical Industry Co., Ltd.) (Commercially available) or the like. One type of (meth) acrylic resin may be used, or two or more types may be used in combination.

  The content of the (meth) acrylic resin in the surface layer is preferably 50% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more.

  The surface layer may further contain a thermoplastic resin other than the (meth) acrylic resin. Other thermoplastic resins have a glass transition temperature of 100 ° C. or higher and a total light transmittance of 85% or higher, and the heat resistance and mechanical strength of the layer obtained by mixing with (meth) acrylic resin. Can be improved.

  Examples of other thermoplastic resins include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins. Polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer and other styrenic polymers; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and other polyesters; nylon 6; And polyamides such as nylon 66 and nylon 610. Among them, acrylonitrile-styrene copolymer and polyvinyl chloride resin are preferable because they are easily compatible with (meth) acrylic resin. The copolymerization ratio (molar ratio) of the acrylonitrile-styrene copolymer is preferably in the range of acrylonitrile: styrene = 1: 10 to 10: 1.

  The surface layer may further contain a matting agent in addition to the same additives as the base material layer, an ultraviolet absorber, a retardation adjusting agent, a deterioration preventing agent and the like.

Fine particles (matting agent)
The surface layer may further contain fine particles (matting agent) as necessary in order to enhance the slipperiness of the surface of the optical film.

  The fine particles may be inorganic fine particles or organic fine particles. Examples of inorganic fine particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples include 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.

  Examples of silicon dioxide fine particles include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., Ltd.), Seahoster KE-P10, KE-P30, KE-P50, KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) and the like are included. Among these, Aerosil R972V, NAX50, Seahoster KE-P30 and the like are particularly preferable because the friction coefficient can be reduced while keeping the turbidity of the obtained film low.

  The primary particle diameter of the fine particles is preferably 5 to 50 nm, and more preferably 7 to 20 nm. A larger primary particle size has a greater effect of increasing the slipperiness of the resulting film, but transparency tends to decrease. Therefore, the fine particles may be contained as secondary aggregates having a particle diameter of 0.05 to 0.3 μm. The size of the primary particles or the secondary aggregates of the fine particles is determined by observing the primary particles or secondary aggregates with a transmission electron microscope at a magnification of 500,000 to 2,000,000 times, and measuring 100 primary particles or secondary aggregates. It can be determined as an average value of the particle diameter.

  The content of fine particles in the surface layer can be 0.05 to 1.0% by mass with respect to the resin components ((meth) acrylic resin and other thermoplastic resins) included in the surface layer, preferably 0.1 It can be set to -0.8 mass%.

  Each of the base material layer and the surface layer may be a single layer or two or more layers. Among them, the optical film has a single base layer and two surface layers sandwiching it, since it has a thin film thickness and can impart good adhesion to the active energy ray-curable adhesive on both sides of the film. (Having a three-layer structure) is preferable. The optical film may further have other functional layers such as a hard coat layer disposed on the surface layer as necessary.

  The total thickness of the optical film is preferably from 10 to 50 μm, preferably from 15 to 35 μm, in order to have a mechanical strength of a certain level or more and to reduce fluctuations in retardation due to heat and humidity. More preferred.

  The ratio of the thickness of the base material layer to the total thickness of the optical film is preferably within a range of 30 to 90%, and more preferably 50 to 80%. If the thickness ratio of the base material layer is too low, the mechanical strength and heat resistance of the optical film may not be sufficient. When the ratio of the thickness of the base material layer is too high, the moisture resistance of the optical film and the affinity with the active energy ray-curable adhesive may not be sufficient.

  When the optical film includes a plurality of base material layers, the “thickness of the base material layer” means the total thickness of the plurality of base material layers. When the optical film includes a plurality of surface layers, the thicknesses of the surface layers may be the same or different from each other, and are preferably the same.

Physical Properties of Optical Film In the environment of 23 ° C. and 55% RH, the in-plane retardation Ro measured at a wavelength of 590 nm is preferably 0 nm or more and 30 nm or less, and more preferably 0 nm or more and 10 nm or less. The retardation Rth in the thickness direction is preferably 0 nm or more and 70 nm or less, and more preferably 0 nm or more and 50 nm or less. The optical film having such a retardation is suitable as a protective film having no retardation adjustment function (a protective film F1 or F4 in FIG. 1 described later), for example.

Retardation Ro and Rth are defined by the following equations, respectively.
Formula (I) Ro = (nx−ny) × d
Formula (II) Rth = {(nx + ny) / 2−nz} × d
(Nx: refractive index in the slow axis direction x in the film plane, ny: refractive index in the direction y perpendicular to the slow axis direction x in the film plane, nz: refractive index in the thickness direction z of the film, d: Film thickness (nm))

Retardation Ro and Rth can be measured, for example, by the following method.
1) Condition the optical film 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.
2) Ro is measured by KOBRA21ADH, Oji Scientific Co., Ltd., when light having a measurement wavelength of 590 nm is incident on the optical film after humidity adjustment in parallel to the normal line of the film surface.
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 optical film (incident angle (θ)) is obtained. 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 of the optical film can be confirmed by KOBRA21ADH.
4) nx, ny, and nz are calculated by KOBRA21ADH from the measured Ro and R (θ) and the above-described average refractive index and film thickness, and Rth at a measurement wavelength of 590 nm is calculated. The measurement of retardation can be performed under conditions of 23 ° C. and 55% RH.

  The angle θ1 (orientation angle) formed by the in-plane slow axis of the optical film and the width direction of the film is preferably −1 ° to + 1 °, more preferably −0.5 ° to + 0.5 °. . The orientation angle θ1 of the optical film can be measured using an automatic birefringence meter KOBRA-WR (Oji Scientific Instruments).

  The internal haze of the optical film measured in accordance with JIS K-7136 is preferably 0.01 to 0.1. The visible light transmittance of the optical film is preferably 90% or more, and more preferably 93% or more.

  The optical film is preferably an optical film for a liquid crystal display device, and specific examples thereof include a polarizing plate protective film, a retardation film (optical compensation film), an antireflection film, an antiglare film, a hard coat film, and the like. More preferred are antireflection films, antiglare films, hard coat films, and the like.

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 a direction perpendicular to the width direction of the film (length direction).

  FIG. 1 is a schematic diagram illustrating an example of a roll body of an optical film. As shown in FIG. 1, a roll body 10 of an optical film has a core 12 and a long optical film 14 wound around the core 12 in the length direction of the film. And in the roll body 10, in order to suppress adhesion | attachment of the optical films 14 laminated | stacked, the embossed part 16 is formed in the width direction both ends of the elongate optical film 14. As shown in FIG.

FIG. 2 is a perspective view showing an example of the vicinity of the embossed portion of the optical film. As shown in FIG. 2, the height D ₀ of the convex portion 16A constituting the embossed portion 16 is preferably 1.0 μm or more and 10.0 μm or less, more preferably 2.0 μm or more and 6.0 μm or less. . The height D ₀ of the convex portion 16A refers to the height from the film surface F (the film surface where the emboss is not formed) to the apex of the convex portion 16A. If the height of the convex portion 16A is less than 1.0 μm, the optical films are likely to adhere to each other, which is not preferable. On the other hand, when the height of the convex portion 16A is too large, the central portion in the width direction of the roll body is easily bent, and it is difficult to maintain the flatness as an optical film.

  The width w of the convex portion 16A can be about 0.05 to 5 mm. The width w of the convex portion 16 </ b> A is expressed as a distance between two points where the convex portion 16 </ b> A intersects the film surface F in the cross section of the embossed portion 16. The interval b between the convex portion 16A and the convex portion 16A is preferably 0.1 to 5 mm, and more preferably 0.5 to 2 mm. The interval b between the convex portions 16A and the convex portions 16A is represented by the distance between the points at which the two convex portions 16A intersect the film surface F in the cross section of the embossed portion 16.

  The width W of the embossed portion 16 is preferably in the range of 0.12 to 2.1% with respect to the width of the optical film. Specifically, although the width W of the embossed portion 16 depends on the width of the optical film, it may be 5 to 25 mm; preferably 10 to 20 mm. If the width W of the embossed portion 16 is too large, the area that can be used as an optical film is reduced. On the other hand, if the width W of the embossed portion 16 is too small, the optical films are likely to adhere to each other.

  The optical film of this invention is embossed on the surface layer which has a (meth) acrylic resin as a main component. However, since the hardness of the surface layer mainly composed of (meth) acrylic resin is low, the strength of the embossed portion formed on the surface layer tends to be low. Thereby, in the roll body of an optical film, the convex part of the embossed part of the film in the vicinity of the core is easily crushed by the weight of the laminated optical film. When the convex portion of the embossed portion is crushed, the laminated optical films are easily adhered to each other; the additive (for example, a plasticizer) contained in the optical film is easily oozed out at the adhered portion. When the additive oozes out, for example, when applying an active energy ray-curable adhesive, a solution for a hard coat layer, or the like to the surface of the optical film, uneven coating tends to occur and workability tends to be lowered.

  Therefore, in the present invention, it is preferable to have an embossed portion that is not easily crushed even when the hardness of the surface layer to be embossed is low; that is, to have an embossed portion having a high strength (elastic modulus). Specifically, the crush resistance of the convex portion of the embossed portion measured by the following method is preferably 40% or more, and more preferably 50% or more.

The crush resistance of the convex part of the embossed part can be measured by the following method. 3 and 4 are partial perspective views showing an example of a method for measuring the crush resistance of the convex portion of the embossed portion.
1) A region including the embossed portion 16 of the optical film 14 is cut into a 5 cm square to obtain a sample film 14A. This sample film 14A is placed on the stage 15 of a constant pressure thickness measuring machine RG-02 (Telock Corporation). Then, the measuring bar of constant pressure thickness measuring machine, put on the embossed portion of the sample film a circular tip of diameter 5 mm, the height D ₀ of the convex portion of the embossed portion while applying an initial load of 10g Measure (see FIG. 3).
2) Next, a weight 18B is arranged on the measuring rod 18A so that a load of 1 kg is applied to the tip of the measuring rod 18A of the thickness measuring machine (see FIG. 4). Then, in the same manner as described above, on the embossed portion of the optical film, a 1 kg load is applied to a circular region having a diameter of 5 mm, and left at 23 ° C. and 55% RH for 10 minutes.
3) Then, without removing the weight, the height D of the convex portion of the embossed portion of the sample film 14A is measured with a 1 kg load applied.
4) Apply the obtained values of D ₀ and D to the following equations to calculate the crush resistance.

  Adjustment of the crushing resistance ratio of the convex portion of the embossed portion is performed by embossing conditions; 1) surface temperature of the embossing roll, 2) material of the back roll, 3) film transport speed, 4) surface temperature of the back roll. The above can be combined and adjusted. Among them, it is more preferable to adjust 1) the surface temperature of the embossing roll, 2) the material of the back roll, and 3) the film conveyance speed. In order to increase the crush resistance of the convex portion of the embossed portion, for example, it is preferable that 1) the surface temperature of the embossing roll be increased, 2) the back roll material be made of metal, and 3) the film transport speed be decreased. .

  The roll length of the optical film in the roll body of the present invention is usually from 1500 m to 8000 m, preferably from 2000 m to 6000 m, more preferably from 3800 m to 6000 m. The diameter of the winding core in the roll body of the present invention can be about 100 mm to 250 mm. The width of the optical film in the roll body of the present invention is about 1.2 to 4 m, preferably about 1.2 to 2.5 m.

  According to this invention, it has an embossed part with high intensity | strength in the width direction both ends of an optical film. Therefore, even in the roll body of the optical film having a large winding length, the convex portion of the embossed portion of the optical film in the vicinity of the core can be made difficult to be crushed by the weight of the laminated optical film. Thereby, it is possible to suppress adhesion between the optical films;

  The roll body of the optical film is preferably packaged and stored with a moisture-proof packaging material. The packaging material can be a sheet or a bag. This is for reducing the performance degradation of the optical film due to the influence of heat and humidity during storage. The moisture-proof packaging material can be, for example, a sheet or bag in which an aluminum vapor deposition layer is formed on a base material such as polyester or polyethylene. The packaging material is preferably multiple (preferably double). When the packaging material is multiplexed (preferably double), the material of each packaging material may be the same or different. The opening of the package is preferably sealed with a sealing member such as rubber or a seal.

  FIG. 5A is a perspective view showing an example of the appearance of the package; FIG. 5B is a cross-sectional view of the package of FIG. 5A. As shown in FIG. 5B, the packaging body 100 includes a roll body 110, an inner packaging material 130a for packaging the roll body 110, an outer packaging material 130b for packaging the roll body 110, an inner packaging material 130a and an outer packaging material 130b. Sealing members 150a and 150b for sealing the openings of the packaging material 130).

  The roll body 110 includes a winding core 111 and a long optical film 113 wound around the core 111. The inner packaging material 130a may be, for example, an aluminum deposition sheet / aluminum deposition layer / PE; and the outer packaging material 130b may be, for example, a polyethylene sheet. As the sealing members 150a and 150b, for example, an adhesive tape (Nitto PP tape, Nichiban Cello tape (registered trademark)) or the like can be used.

3. Method for Producing Optical Film Roll Body The optical film roll body of the present invention is preferably at least a solution co-casting method or a melt co-casting method; A step of obtaining an optical film by a drawing method.

  That is, the roll body of the optical film of the present invention is a process for preparing 1) a base layer dope containing a cellulose ester and an organic solvent, and a surface layer dope containing a (meth) acrylic resin and an organic solvent. 2) a step of casting the substrate layer dope and the surface layer dope while being laminated simultaneously or sequentially on a casting support; 3) the laminated base layer dope and the surface layer. Removing the organic solvent contained in the dope to obtain a laminate; 4) stretching the laminate to include a substrate layer and a surface layer disposed on at least one surface of the substrate layer Step of obtaining an optical film; 5) Preferably, the optical film is manufactured through a step of forming embossed portions at both ends in the width direction on the surface layer of the optical film.

1) Step of preparing dope Cellulose ester and, if necessary, additives are dissolved in an organic solvent to obtain base layer dope A containing cellulose ester as a main component. Similarly, a (meth) acrylic resin or, if necessary, an additive or the like is dissolved in an organic solvent to obtain a surface layer dope B containing the (meth) acrylic resin as a main component.

  Each component can be dissolved in an organic solvent by a room temperature dissolution method, a cooling dissolution method, or a high temperature dissolution method. The cellulose ester is dissolved in an organic solvent by, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, Kaihei 10-45950, JP 2000-53784, JP 11-322946, JP 11-322947, JP 2-276830, JP 2000-273239, JP 11-71463, JP No. 04-259511, JP-A No. 2000-273184, JP-A No. 11-323017, JP-A No. 11-302388, and the like. In particular, the dissolution in a non-chlorinated solvent can be carried out by the method described on pages 22 to 25 of the aforementioned public technical number 2001-1745. In the case of dissolving at a high temperature, it is preferably carried out at a pressure higher than the boiling point of the organic solvent to be used.

  The obtained dope can be subjected to solution concentration and filtration as necessary. The solution concentration and filtration method is described in detail on page 25 of Kogyo No. 2001-1745.

(Organic solvent)
The organic solvent used for the preparation of the dope may be a conventionally known organic solvent. For example, a solubility parameter in the range of 17 to 22 is preferable. Solubility parameters are described in, for example, J. Brandrup, E.I. “Polymer Handbook (4th. Edition)” such as H, and the like described in VII / 671 to VII / 714. Lower aliphatic hydrocarbon chloride, lower aliphatic alcohol, ketone having 3 to 12 carbon atoms, ester having 3 to 12 carbon atoms, ether having 3 to 12 carbon atoms, fat having 5 to 8 carbon atoms Group hydrocarbons, aromatic hydrocarbons having 6 to 12 carbon atoms, fluoroalcohols (for example, described in paragraph No. [0020] of JP-A-8-143709, paragraph No. [0037] of JP-A-11-60807) Compound) and the like.

  One type of organic solvent may be used, or two or more types may be combined. When combining two or more types, it is preferable to use a mixture of a good solvent and a poor solvent in order to stably obtain an optical film having a good surface shape. The mixing ratio of the good solvent and the poor solvent is preferably 60 to 99% by mass for the good solvent and 40 to 1% by mass for the poor solvent.

  A good solvent is one that dissolves the resin used alone, and a poor solvent is one that swells or does not dissolve the resin used alone. Examples of good solvents include organic halogen compounds such as methylene chloride and dioxolanes. As examples of the poor solvent, methanol, ethanol, n-butanol, cyclohexane and the like are preferably used.

  The poor solvent contained in the base layer dope A and the surface layer dope B is preferably alcohol, and preferably methanol, in order to shorten the drying time of the dope on the casting support. The content of methanol in the organic solvent contained in the base layer dope A and the surface layer dope B can be 20 to 35% by mass, preferably 21 to 35% by mass, more preferably 25 to 30% by mass. It can be.

(Dope solid content concentration)
The solid content concentration of the base layer dope A and the surface layer dope B (concentration of components that become solid after the dope is dried) can be appropriately set according to the molecular weight of the resin. In order to obtain a dope having a viscosity suitable for solution casting film formation, the solid content concentration is preferably 16 to 30% by mass, and more preferably 18 to 25% by mass.

  In order to obtain a good planar film by co-casting, it is preferable that the solid content concentrations of the base layer dope A and the surface layer dope B are approximately the same. The difference in solid content concentration between the surface layer dope B and the base layer dope A is preferably within 10% by mass, and more preferably within 5% by mass.

  That is, the solid content concentration of the surface layer dope B is preferably 16 to 30% by mass, and the difference from the solid content concentration of the base layer dope A is preferably 10% by mass or less.

(Complex viscosity of dope)
The complex viscosity of the solid content concentration of the base layer dope A and the surface layer dope B is preferably 10 to 80 Pa · s or less, more preferably 20 to 80 Pa · s, and more preferably 25 to 70 Pas. More preferably it is. By making the complex viscosity within the above range, the solution casting suitability can be further improved. The complex viscosity of the dope refers to a viscosity measured by solution shear rheometer measurement.

  Viscosity can be measured as follows. 1 mL of the sample solution is set in a rheometer (CLS 500), and the viscosity is measured using a Steel Cone (both manufactured by TA Instruments) having a diameter of 4 cm / 2 °.

  The sample solution is kept warm at the measurement start temperature until the liquid temperature becomes constant, and then the measurement is started. The temperature of the sample solution may be a temperature at the time of casting the dope, and is preferably −5 to 70 ° C., more preferably −5 to 35 ° C.

  The viscosity of the base layer dope A and the viscosity of the surface layer dope B may be different, and the viscosity of the surface layer dope B is preferably smaller than the viscosity of the base layer dope A. Among them, the complex viscosity of the base layer dope A and the surface layer dope B is 10 to 80 Pa · s or less, and the complex viscosity of the surface layer dope B is higher than the complex viscosity of the base layer dope A. A large value is preferable from the viewpoint of improving the film surface after film formation.

2) Process of casting while laminating simultaneously or sequentially Casting the base layer dope A and the surface layer dope B while laminating simultaneously or sequentially on the casting support.

  The co-casting of the base layer dope A and the surface layer dope B can be performed by a known co-casting method. For example, each dope may be sequentially cast from a plurality of casting openings provided at intervals in the traveling direction of the casting support, and laminated, for example, Japanese Patent Laid-Open Nos. 61-158414 and 1- The methods described in JP-A Nos. 122419 and 11-198285 can be applied. Further, the dope may be cast from two casting ports at the same time and laminated, for example, Japanese Patent Publication Nos. 60-27562, 61-94724, 61-947245 and 61-61. The methods described in JP-A-104813, JP-A-61-158413, and JP-A-6-134933 can be applied.

  For example, when obtaining an optical film having a three-layer structure of surface layer / base material layer / surface layer, the surface layer dope B / base material layer dope A / surface layer dope B are co-cast in order from the casting support side. Can do. The plurality of surface layer dopes B in one laminate may have the same composition or different compositions.

  The casting support is not particularly limited, but is preferably a drum or a band. The surface of the support is preferably finished in a mirror state. The casting and drying methods in the solvent casting method are described in U.S. Pat. Nos. 2,336,310, 2,367,603, 2,429,078, 2,429,297, 2,429,978, 2,607,704, 2,273,069, and 2,739,070, British Patent 6,407,331. No. 736892, JP-B Nos. 45-4554, 49-5614, JP-A-60-176834, No. 60-203430, and No. 62-115035.

  The surface temperature of the casting support on which the substrate layer dope A and the surface layer dope B are cast is preferably 5 ° C. or less, more preferably −30 to 5 ° C., and −10 to 2 ° C. More preferably.

3) Step of removing the organic solvent contained in the dope to obtain a laminate The cast base material dope A and the surface layer dope B may be dried by heating with a temperature control plate as described above. It may be dried by being exposed to wind for 2 seconds or longer. The obtained laminate can be peeled off from the casting support and dried with high-temperature air while successively changing the temperature from 100 ° C. to 160 ° C. to evaporate the residual solvent. This drying method is described in Japanese Patent Publication No. 5-17844.

4) Step of stretching laminate The above laminate is stretched to obtain an optical film having a base layer mainly composed of cellulose ester and a surface layer mainly composed of (meth) acrylic resin. By stretching the laminate in this manner, the tensile modulus of the laminate can be increased and the surface hardness can be increased.

  The residual solvent amount at the start of stretching of the laminate is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, and further preferably 3 to 20% by mass. When a laminate having a residual solvent amount of less than 1% by mass is stretched, it is not preferable because stretching becomes difficult and the film may be broken. When the residual solvent amount exceeds 50% by mass, the effect of increasing the elastic modulus is reduced, and sufficient surface hardness cannot be obtained.

  The residual solvent amount is represented by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is a mass at an arbitrary point of the laminate, and N is a mass when the laminate for which M is measured is dried at 110 ° C. for 3 hours.

  Stretching can be performed in the transport direction (MD direction), the width direction (TD direction), the oblique direction, or a combination thereof. In order to reduce the Ro of the obtained film and increase the Rth, it is preferable to stretch in the biaxial directions orthogonal to each other; for example, both the transport direction (MD direction) and the width direction (TD direction).

  Biaxial stretching may be performed simultaneously in two directions, for example, or sequentially. When extending | stretching sequentially, you may change extending | stretching temperature for every extending | stretching.

  In the case of simultaneous biaxial stretching, the stretching temperature is preferably 110 ° C to 190 ° C, more preferably 120 ° C to 150 ° C, and further preferably 130 ° C to 150 ° C. By simultaneous biaxial stretching, the haze is likely to be increased to some extent, but the necessary retardation value can be effectively increased.

  When sequentially biaxially stretching, it is preferable to stretch in the width direction (TD direction) after stretching in the transport direction (MD direction). The stretching temperature can be the same as described above.

  It is preferable to perform a draw ratio in the range which becomes 1.1 to 4.0 times combining a conveyance direction (MD direction) and a width direction (TD direction). The stretch ratio in which the transport direction (MD direction) and the width direction (TD direction) are combined means the product of the stretch ratio in the transport direction (MD direction) and the stretch ratio in the width direction (TD direction). For example, when the film is stretched 2.0 times in the transport direction (MD direction) and 1.5 times in the width direction (TD direction), the stretch ratio of the transport direction (MD direction) and the width direction (TD direction) is combined. Is 3.0 times.

  Specifically, the draw ratio in the width direction (TD direction) is preferably 1.05 to 1.5 times, and the draw ratio in the transport direction (MD direction) is 1.01 to 1.5 times. Preferably there is.

  Stretching in the transport direction (MD direction) is preferably performed using a nip roll, and stretching in the width direction (TD direction) is preferably performed with a tenter.

  The combination of drying and stretching is preferable because the process can be shortened. The stretching temperature in the stretching step is preferably 110 to 190 ° C, and more preferably 120 to 150 ° C. When the stretching temperature is 120 ° C. or higher, an increase in haze of the obtained film is easily suppressed. When the stretching temperature is 150 ° C. or lower, the optical development property and elastic modulus of the obtained film can be increased, which is preferable. When the temperature of the laminate is too high, the plasticizer is volatilized. Therefore, when a low molecular plasticizer that easily volatilizes is used as the plasticizer, a range of room temperature (15 ° C.) to 145 ° C. is preferable.

  The film conveyance speed in the optical film manufacturing process is preferably 60 to 200 m / min, and more preferably 80 to 150 m / min. If the film transport speed is too low, the productivity tends to decrease. When the conveyance speed of a film is too high, for example, the film is easily broken. The step of forming the embossed portion to be described later may be performed by winding up the optical film once to make a roll body, and then unwinding the optical film; it may be performed as it is without winding up the optical film. Once the optical film is wound up into a roll body, and then unrolled from the roll body to form an embossed part, the film transport speed in the process of forming the embossed part is the optical film manufacturing process. The film conveyance speed may be the same or different.

5) The process of forming an embossed part Embossing is performed on the surface layer which has a (meth) acrylic resin as a main component of the obtained optical film. FIG. 6 is a schematic diagram illustrating an example of the embossing apparatus 20. As shown in FIG. 6, the embossing apparatus includes an embossing roll 22 and a back roll 24 disposed so as to face the embossing roll 22 with the optical film 14 interposed therebetween.

  The material of the back roll 24 is preferably made of metal in order to uniformly cool the film on which the embossed portion is formed. The type of metal can be, for example, SUS, stainless steel, aluminum, titanium, hard chrome, and the like. Metal back rolls, for example, have higher heat dissipation and easier cooling of the film than rubber, plastic, and ceramic back rolls, making it easy to crystallize (meth) acrylic resin uniformly and high. An embossed portion having strength (high elastic modulus) can be formed.

  The clearance between the embossing roll 22 and the back roll 24 may be about 1 μm to 30 μm, preferably about 1 to 15 μm. The nip pressure between the embossing roll 22 and the back roll 24 can be about 100 to 10,000 Pa.

  And the embossing roll 22 and the back roll 24 nip the both ends in the width direction of the optical film 14, and emboss the both ends in the width direction of the film.

  The surface temperature of the embossing roll 22 is preferably 150 to 250 ° C. If the surface temperature of the embossing roll 22 is less than 150 ° C., the film cannot be sufficiently melted. Therefore, even if it is cooled, the (meth) acrylic resin is not sufficiently crystallized, and a strong embossed part is formed. Hateful. On the other hand, when the surface temperature of the embossing roll is higher than 250 ° C., the film is melted too much, and the melted film tends to stick to the embossing roll. The roll diameter of the embossing roll 22 can be about 30 to 60 cm.

  Although the surface temperature of the back roll 24 is based also on the surface temperature of the embossing roll 22, it is preferable to set it as 30-100 degreeC, and it is more preferable to set it as 40-80 degreeC. When the surface temperature of the back roll is less than 30 ° C., the film is cooled too rapidly, and it is difficult to uniformly crystallize the (meth) acrylic resin, and it is difficult to obtain an embossed portion having a high elastic modulus. On the other hand, when the surface temperature of the back roll exceeds 100 ° C., it is difficult to cool the (meth) acrylic resin contained in the film, so that not only is it difficult to crystallize, but the film is thermally expanded, The front and back of the film is easy to wave. When the undulations of the front and back surfaces of the film near the embossed portion occur, the films are likely to stick to each other and the film is easily torn.

  The film conveyance speed during embossing is preferably 40 to 200 m / min, and more preferably 60 to 130 m / min. If the film conveyance speed is less than 40 m / min, the productivity tends to decrease. On the other hand, when the conveyance speed of the film is more than 200 m / min, the pressure of the embossing roll and the heat of the embossing roll are not easily transmitted to the film. This makes it difficult to uniformly crystallize the (meth) acrylic resin in the surface layer, and it is difficult to form an embossed portion with high strength.

  In other words, in order to form an embossed portion that is not easily crushed, the surface layer containing (meth) acrylic resin as a main component is sufficiently melted with an embossing roll, and 2) the (meth) acrylic resin melted with a back roll is slowly melted. It is considered important to cool and crystallize. For that purpose, it is preferable to adjust by combining at least two or more of 1) the surface temperature of the embossing roll, 2) the material of the back roll, 3) the film transport speed, and 4) the surface temperature of the back roll. Especially, it is preferable to adjust 1) the surface temperature of an embossing roll, 2) the material of a back roll, and 3) the conveyance speed of a film in the above-mentioned range, respectively.

  The obtained long optical film is wound up in the film length direction (perpendicular to the width direction) using a winder. The winding method is not particularly limited, and may be a constant torque method, a constant tension method, a taper tension method, or the like. The winding tension when winding the optical film can be about 50 to 170N.

4). Polarizing plate The polarizing plate of the present invention includes a polarizer and an optical film that is disposed on at least one surface thereof and is obtained from the roll of the optical film of the present invention. The optical film obtained from the roll body of the optical film of the present invention is an optical film obtained by removing the slits from the embossed portion. The optical film may be disposed directly on the polarizer, or may be disposed through another film or layer.

  A polarizer is an element that allows only light having a polarization plane in a certain direction to pass therethrough. A typical example of the polarizer is a polyvinyl alcohol-based polarizing film, and there are one in which a polyvinyl alcohol-based film is dyed with iodine and one in which a dichroic dye is dyed.

  The polarizer can be obtained by uniaxially stretching a polyvinyl alcohol film and then dyeing; or, after dying a polyvinyl alcohol film, it can be uniaxially stretched and preferably further subjected to a durability treatment with a boron compound. The film thickness of the polarizer is preferably in the range of 5 to 30 μm, and more preferably in the range of 5 to 15 μm.

  Examples of the polyvinyl alcohol film include ethylene unit content of 1 to 4 mol%, polymerization degree of 2000 to 4000, and saponification degree of 99.0 to 99 described in JP2003-248123A, JP2003-342322A, and the like. 99 mol% ethylene-modified polyvinyl alcohol is preferably used.

  When the optical film of the present invention is disposed on one surface of the polarizer, a retardation film may be disposed on the other surface of the polarizer. The retardation of the retardation film can be set according to the type of liquid crystal cell to be combined. For example, the in-plane retardation Ro (590) measured at a wavelength of 590 nm under 23 ° C. RH 55% of the retardation film is preferably in the range of 30 to 150 nm, and the retardation Rth (590) in the thickness direction is A range of 70 to 300 nm is preferable. A retardation film having a retardation in the above range can be preferably used for, for example, a VA liquid crystal cell or an IPS liquid crystal cell.

  The bonding of the optical film and the polarizer is not particularly limited, but can be performed using a completely saponified polyvinyl alcohol adhesive, an active energy ray-curable adhesive, or the like. It is preferable to use an active energy ray-curable adhesive because the obtained adhesive layer has a high elastic modulus and can easily suppress deformation of the polarizing plate.

  The active energy ray-curable adhesive may further contain a curable compound, a photopolymerization initiator, and a photosensitizer and a photosensitization aid as necessary.

  The curable compound may be a radically polymerizable compound such as a (meth) acrylic compound or a cationically polymerizable compound such as an epoxy compound. The epoxy compound may be an aromatic epoxy compound, an alicyclic epoxy compound, an aliphatic epoxy compound, or the like, and is preferably an alicyclic epoxy compound. The epoxy compound may be one type or two or more types. For example, you may combine an alicyclic epoxy compound and the aliphatic epoxy compound which does not have an alicyclic structure.

Examples of the alicyclic epoxy compounds include hydrogenated aromatic epoxy compounds, cyclohexane-based, cyclohexylmethyl ester-based, and cyclocyclohexylmethyl ether-based epoxy compounds. Especially, since acquisition is easy and it is easy to raise the storage elastic modulus of hardened | cured material, the following compounds (ep-1)-(ep-11) are preferable.

In said formula, R < ¹ > -R < ²⁴ > represents a hydrogen atom or a C1-C6 alkyl group each independently. The alkyl group having 1 to 6 carbon atoms may be a straight chain, may have a branch, or may have an alicyclic ring.

Y ⁸ represents an oxygen atom or an alkanediyl group having 1 to 20 carbon atoms. Y ^{1 to} Y ⁷ each independently represent a straight chain, may have a branch, or represent an alkanediyl group having 1 to 20 carbon atoms which may have an alicyclic ring. n, p, q and r each independently represents a number of 0 to 20.

  A photoinitiator is selected according to the kind of curable compound, and may be a photoradical polymerization initiator or a photocationic polymerization initiator. Examples of photo radical polymerization initiators include acetophenones such as 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone Benzoin ether compounds such as benzoin ethyl ether; benzophenone compounds such as 3,3′-dimethyl-4-methoxybenzophenone and the like. Examples of the photocationic polymerization initiator include aryldiazonium salts, arylsulfonium salts (for example, triarylsulfonium salts), aryliodonium salts, allene-ion complexes, and the like. Content of a photoinitiator is about 0.1-10 mass parts normally with respect to 100 mass parts of curable compounds, Preferably it can be set as 0.5-5 mass parts.

  The photosensitizer includes anthracene compounds such as 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, and 9,10-dibutoxyanthracene. The photosensitizer may be 0.1 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the active energy ray-curable adhesive.

  The photosensitizing assistant includes naphthalene-based photosensitizing assistants such as 1,4-dimethoxynaphthalene and 1,4-diethoxynaphthalene. The photosensitizing assistant may be 0.1 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the active energy ray-curable adhesive.

  The manufacturing method of the polarizing plate using the active energy ray-curable adhesive is, for example, 1) a pretreatment process for easily bonding the surface of the optical film to which the polarizer is bonded, and 2) the bonding surface of the polarizer and the optical film. Adhesive application step of applying the following active energy ray-curable adhesive to at least one of them, 3) a bonding step of bonding the polarizer and the optical film through the obtained adhesive layer, and 4) adhesion A curing step of curing the adhesive layer in a state where the polarizer and the optical film are bonded to each other through the agent layer may be included. What is necessary is just to implement the pre-processing process of 1) as needed.

(Pretreatment process)
In the pretreatment step, an easy adhesion treatment is performed on the adhesive surface of the optical film with the polarizer. When bonding an optical film to both surfaces of a polarizer, easy adhesion processing is performed on the bonding surface of each optical film with the polarizer. Examples of the easy adhesion treatment include corona treatment and plasma treatment.

(Adhesive application process)
In the adhesive application step, the active energy ray-curable adhesive is applied to at least one of the adhesive surfaces of the polarizer and the optical film. When the active energy ray-curable adhesive is applied directly to the surface of the polarizer or the optical film, the application method is not particularly limited. For example, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Moreover, after casting an active energy ray hardening adhesive between a polarizer and an optical film, the method of pressurizing with a roll etc. and spreading uniformly can also be utilized.

(Bonding process)
Thus, after apply | coating an active energy ray hardening adhesive, it uses for a bonding process. In this bonding step, for example, when an active energy ray-curable adhesive is applied to the surface of the polarizer in the previous application step, an optical film is superimposed thereon. When the active energy ray-curable adhesive is applied to the surface of the optical film in the previous application step, a polarizer is superimposed thereon. Moreover, when an active energy ray-curable adhesive is cast between the polarizer and the optical film, the polarizer and the optical film are superposed in that state. When an optical film is bonded to both sides of a polarizer, and both sides use an active energy ray-curable adhesive, the optical film is superimposed on each side of the polarizer via an active energy ray-curable adhesive. Is done. Usually, in this state, both sides (if the optical film is superimposed on one side of the polarizer, the polarizer side and the optical film side, and if the optical film is superimposed on both sides of the polarizer, The film is pressed with a roll or the like from the film side). As the material of the roll, metal, rubber or the like can be used. The rolls arranged on both sides may be the same material or different materials.

(Curing process)
In the curing step, the uncured active energy ray-curable adhesive is irradiated with active energy rays to cure the adhesive layer containing the epoxy compound or the oxetane compound. Thereby, the laminated polarizer and the optical film are bonded via the active energy ray-curable adhesive. When bonding an optical film to the single side | surface of a polarizer, you may irradiate an active energy ray from either a polarizer side or an optical film side. Moreover, when bonding an optical film on both surfaces of a polarizer, in the state which piled up the optical film on both surfaces of the polarizer through the active energy ray curable adhesive, respectively, active energy from any one optical film side It is advantageous to irradiate the line and simultaneously cure the active energy ray curable adhesive on both sides.

  As the active energy ray, visible light, ultraviolet ray, X-ray, electron beam or the like can be used, and since it is easy to handle and has a sufficient curing speed, generally, an electron beam or ultraviolet ray is preferably used.

  Any appropriate condition can be adopted as the electron beam irradiation condition as long as the adhesive can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably in the range of 5 to 300 kV, more preferably in the range of 10 to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the adhesive and may be insufficiently cured. If the acceleration voltage exceeds 300 kV, the penetration force through the sample is too strong and the electron beam rebounds, There is a risk of damaging the polarizer. The irradiation dose is in the range of 5 to 100 kGy, more preferably in the range of 10 to 75 kGy. When the irradiation dose is less than 5 kGy, the adhesive becomes insufficiently cured, and when it exceeds 100 kGy, the transparent optical film and the polarizer are damaged, resulting in a decrease in mechanical strength and yellowing, thereby obtaining predetermined optical characteristics. I can't.

Arbitrary appropriate conditions can be employ | adopted for the irradiation conditions of an ultraviolet-ray, if it is the conditions which can cure | harden the said adhesive agent. The dose of ultraviolet rays is preferably in the range of 50~1500mJ / cm ² in accumulated light quantity, and even more preferably in the range of 100 to 500 mJ / cm ^2.

  In the polarizing plate obtained as described above, the thickness of the adhesive layer is not particularly limited, but is usually in the range of 0.01 to 10 μm, and preferably in the range of 0.5 to 5 μm.

5). Liquid Crystal Display Device The liquid crystal display device of the present invention includes a liquid crystal cell and a pair of polarizing plates that sandwich the liquid crystal cell. And at least one of a pair of polarizing plates contains the optical film obtained from the roll body of the optical film of this invention.

  FIG. 7 is a schematic diagram illustrating an example of a basic configuration of a liquid crystal display device. As shown in FIG. 7, the liquid crystal display device 30 includes a liquid crystal cell 40, a first polarizing plate 50 and a second polarizing plate 60 that sandwich the liquid crystal cell 40, and a backlight 70.

  As the liquid crystal cell 40, various display methods such as STN, TN, OCB, HAN, VA (MVA, PVA), and IPS have been proposed. In order to obtain high contrast, the VA (MVA, PVA) method is preferable.

  A VA liquid crystal cell includes a pair of transparent substrates and a liquid crystal layer sandwiched between them.

  Of the pair of transparent substrates, one transparent substrate is provided with a pixel electrode for applying a voltage to the liquid crystal molecules. The counter electrode may be arranged on the one transparent substrate (on which the pixel electrode is arranged) or on the other transparent substrate. In order to increase the aperture ratio, the pixel electrode (on which the pixel electrode is arranged) is arranged. It is preferable to arrange on the one transparent substrate.

  The liquid crystal layer includes liquid crystal molecules having negative or positive dielectric anisotropy. The liquid crystal molecules are liquid crystal molecules when no voltage is applied (when an electric field is not generated between the pixel electrode and the counter electrode) due to the alignment regulating force of the alignment film provided on the liquid crystal layer side surface of the transparent substrate. Are oriented so that their long axes are substantially perpendicular to the surface of the transparent substrate.

  In the liquid crystal cell thus configured, an electric field is generated between the pixel electrode and the counter electrode by applying an image signal (voltage) to the pixel electrode. Thereby, the liquid crystal molecules initially aligned perpendicularly to the surface of the transparent substrate are aligned so that the major axis thereof is in the horizontal direction relative to the substrate surface. In this way, the liquid crystal layer is driven, and the image display is performed by changing the transmittance and reflectance of each sub-pixel.

  The first polarizing plate 50 is disposed on the viewing side, the first polarizer 52, the protective film 54 (F1) disposed on the viewing side surface of the first polarizer 52, and the first And a protective film 56 (F2) disposed on the surface of the polarizer 52 on the liquid crystal cell side. The second polarizing plate 60 is disposed on the backlight 70 side, the second polarizer 62, a protective film 64 (F3) disposed on the liquid crystal cell side surface of the second polarizer 62, A protective film 66 (F4) disposed on the backlight side surface of the second polarizer 62; One of the protective films 56 (F2) and 64 (F3) may be omitted as necessary.

  Of the protective films 54 (F1), 56 (F2), 64 (F3) and 66 (F4), at least one of the protective films 54 (F1) and 66 (F4) is obtained from the roll body of the optical film of the present invention. It is preferable to use an optical film.

  In the following, the invention will be described in more detail with reference to examples. These examples do not limit the scope of the present invention.

1. Optical film materials 1) Cellulose ester

2) (Meth) acrylic resin

化合物Ａ：ＳＰ値＝１２．８

化合物Ｂ：ＳＰ値＝１１．４

化合物１〜４：いずれも平均置換度７．０

ＰＭＭＡ：ポリメチルメタクリレート（ＳＰ値＝８．７）
ポリエスチレン（ＳＰ値＝９．１） 3) Additive

Compound A: SP value = 12.8

Compound B: SP value = 11.4

Compounds 1-4: All have an average degree of substitution of 7.0

PMMA: Polymethylmethacrylate (SP value = 8.7)
Polystyrene (SP value = 9.1)

  The SP value of the compound was calculated based on the calculation method described in p. 54 to 57 of Reference Literature: Basic Science of Coating, Yuji Harada, Tsuji Shoten (1977).

2. Preparation of Dope Each component such as cellulose acylate resin in Table 2, (meth) acrylic resin in Table 3, polyester compound in Table 4 and solvent is mixed so as to have the composition shown in Table 5, A7 and C1-C22 were prepared respectively. The solvent composition was 50 parts by mass of methanol with respect to 500 parts by mass of dichloromethane. The solvent concentration of the dope in Table 5 represents the mass (mass%) of the solvent with respect to the total mass of the dope.

3. Production of optical film (Example 1)
Simultaneous multi-layer casting was performed so that the dopes A1 and C1 shown in Table 5 were laminated on the traveling stainless steel band in the order of the dope A1 / doped C1 / dope A1 from the casting die. The temperature of the dope to be cast was 35 ° C., the temperature of the stainless steel band was 15 ° C., the casting speed was 50 m / min, and the casting width was 1.8 m. The solvent in the dope on the stainless steel band was evaporated and removed until the residual solvent amount was about 100%, and then the obtained film was peeled from the stainless steel band.

  The obtained film-like material was further dried at 35 ° C., and then slit to have a width of 1.65 m. Next, the film was stretched 30% in the width direction while applying hot air at 160 ° C. with a tenter, and then stretched 30% in the transport direction. The amount of residual solvent in the film-like material at the start of stretching was 5%.

The resulting film was dried at 125 ° C. for 15 minutes while being transported by a number of rolls in a drying apparatus, then slit to 2.2 m width, and the height of the convex portions was 10 μm at both ends in the width direction. The embossed portion (the width W of the embossed portion: 15 mm) having a width w of the portion of 100 μm and an interval between the convex portions of 1000 μm was formed. Embossing was performed under the following conditions.
(Embossing conditions)
Embossing roll Material: Stainless steel Surface temperature: 200 ° C
Back roll Material: Stainless steel Temperature: 60 ℃
Film transport speed: 100 m / min Transport tension: 120 N / m
Clearance between emboss roll and back roll: 27μm
Nip pressure between emboss roll and back roll: 150Pa

  The obtained long optical film having a width of 2.2 m, a length of 3800 m, and a thickness of 25 μm was wound in the length direction to obtain an optical film roll. The obtained optical film had a three-layer structure of A1 layer (surface layer) / C1 layer (base material layer) / A1 layer (surface layer), and the thickness was 5 μm / 15 μm / 5 μm.

(Examples 1-4, Comparative Examples 1-4)
A roll body of the optical film was produced in the same manner as in Example 1 except that the layer configuration was changed as shown in Table 6.

(Examples 5-15, Comparative Examples 5-6)
A roll body of an optical film was produced in the same manner as in Example 1 except that the thickness ratio of each layer was changed as shown in Table 10.

(Examples 16 to 21)
A roll body of an optical film was produced in the same manner as in Example 1 except that the type of dope C1 (specifically, the type of cellulose ester contained in dope C1) was changed as shown in Table 6.

(Examples 22 to 35)
A roll body of an optical film was produced in the same manner as in Example 1 except that the type of dope C1 (specifically, the type of additive contained in dope C1) was changed as shown in Table 7.

(Examples 36 to 41, Comparative Examples 7 to 8)
A roll body of an optical film was produced in the same manner as in Example 1 except that the kind of dope A1 was changed as shown in Table 7.

(Examples 42 to 48)
A roll body of the optical film was produced in the same manner as in Example 1 except that the winding length of the roll body of the optical film was changed as shown in Table 12.

(Examples 49-62, Comparative Examples 9-14)
A roll body of the optical film was produced in the same manner as in Example 1 except that the embossing conditions (conveyance speed, back roll material, emboss roll temperature) were changed as shown in Table 8. In Examples 49 to 54 and Comparative Example 9, the film formed was once wound up into a roll; the film was unwound and embossed.

(Examples 63 to 79)
A roll body of an optical film was produced in the same manner as in Example 1 except that the stretching conditions (width direction stretching ratio, transport direction stretching ratio, transport speed) were changed as shown in Table 9. In Examples 73 to 79, after the formed film was once wound up into a roll, it was unwound and embossed.

The obtained roll body was packaged with a double packaging bag material as shown in FIGS. 5A and 5B described above, and each opening was fastened with a rubber band (sealing member) to obtain a package body.
Inner packaging material: Aluminum deposition sheet (PET (10μm) / Aluminum deposition layer / PE (15μm) laminated sheet Outer packaging material: Polyethylene sheet

  The obtained package was stored at 23 ° C. and 80% RH for 40 hours. On the other hand, the roll body of Example 2 was stored as it was without packaging. Thereafter, the roll body was taken out of the bag and subjected to the following evaluations (crush resistance, emboss chipping, adhesiveness).

[Crush resistance]
10 parts of 5 cm square sample films were prepared by cutting off the portion of the obtained optical film where the embossed part was applied. The sample film was arrange | positioned on the stage of constant-pressure thickness measuring machine RG-02 (TECLOCK Co., Ltd.). Then, as shown in FIG. 4, the convex end of the embossed portion with the initial load of 10 g is applied on the embossed portion of the sample film with the circular tip of the measuring rod of the constant pressure thickness measuring machine being 5 mm in diameter. The height D _{0 of the part} was measured.

Next, a weight was placed on the measuring rod so that a load of 1 kg was applied to the measuring tip of the thickness measuring machine. In the same manner as described above, a 1 kg load was applied to a circular region having a diameter of 5 mm on the embossed portion of the optical film, and the plate was left at 23 ° C. and 55% RH for 10 minutes. Then, the height D of the convex part of the embossed part of the sample film was measured with a 1 kg load applied without removing the weight. The obtained measured values were applied to the following formulas to calculate the crush resistance.
Crush resistance (%) = D / D ₀ × 100
The same measurement was performed on the other nine sample films, and the crush resistance was calculated. And the average value of the crushing resistance obtained by 10 times of measurement was calculated | required.

[Emboss missing]
Of the optical film wound up in a roll, the embossed portion of the optical film near the core was magnified 10 times with an optical microscope, and the shape of the convex portion of the embossed portion was observed. And the number of the convex part by which the chip | tip of the edge part was observed was counted among 100 square-shaped convex parts.
A: No chipping at the end was observed in any of the 100 convex portions. B: Chipping at the end was observed at one or two of the 100 convex portions. Δ: 100 Ends of chipping were observed in 3 to 5 of the convex parts of the X. End: chipping of end parts was observed in 6 or more of the 100 convex parts.

[Adhesiveness]
1) Preparation of Polarizer A 30 μm thick polyvinyl alcohol film 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 5 times. This uniaxially stretched film was washed with water and dried to obtain a polarizer having a thickness of 10 μm.

2) Preparation of active energy ray-curable adhesive The following components were mixed and then defoamed to prepare an active energy ray-curable adhesive. Triarylsulfonium hexafluorophosphate was blended as a 50% propylene carbonate solution, and the solid content of triarylsulfonium hexafluorophosphate was shown below.
(Composition of active energy ray-curable adhesive)
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate: 45 parts by mass Epolide GT-301 (alicyclic epoxy resin manufactured by Daicel Chemical Industries): 40 parts by mass 1,4-butanediol diglycidyl ether: 15 parts by mass Triarylsulfonium hexafluorophosphate: 2.3 parts by mass 9,10-dibutoxyanthracene: 0.1 parts by mass 1,4-diethoxynaphthalene: 2.0 parts by mass

3) Production of polarizing plate On the produced optical film, the active energy ray-curable adhesive prepared above was applied using a micro gravure coater so that the dry thickness was 5 μm, and the active energy ray-curable adhesive was applied. A layer was formed. The application was performed under the conditions of gravure roller # 300, rotation speed 140% / line speed.

An optical film having an active energy ray-curable adhesive layer formed thereon was placed on one surface of the produced polarizer to obtain a laminate of polarizer / active energy ray-curable adhesive layer / optical film. The obtained laminate was bonded with a roller machine. And the ultraviolet-ray was irradiated from the optical film side of the laminated body bonded together, the active energy ray hardening adhesive layer was hardened, and the polarizing plate was obtained. Ultraviolet rays were irradiated so that the line speed was 20 m / min and the integrated light amount was 250 mJ / cm ² .

The operation of peeling off the optical film of the produced polarizing plate from the polarizer was performed 10 times, and the adhesion interface with the optical film / polarizer was visually observed. Thereby, the adhesiveness of the optical film / polarizer was evaluated according to the following criteria.
◎: 10 times does not completely peel off ○: 10 times does not completely peel, but some may peel off △: 1 to 3 times out of 10 times ×: 4 times or more out of 10 times Completely peel off

The production conditions of the optical films of Examples 1 to 21 and Comparative Examples 1 to 6 are shown in Table 6; the storage conditions and evaluation results of the roll bodies are shown in Table 10. Similarly, the production conditions of the optical films of Examples 22 to 41 and Comparative Examples 7 to 8 are shown in Table 7; the storage conditions and evaluation results of the roll bodies are shown in Table 11. The production conditions of the optical films of Examples 42 to 62 and Comparative Examples 9 to 14 are shown in Table 8; the storage conditions and evaluation results of the roll bodies are shown in Table 12. The production conditions of the optical films of Examples 63 to 79 are shown in Table 9; the storage conditions and evaluation results of the roll bodies are shown in Table 13.

  The optical films of Examples 1 to 79 have a higher crushing resistance of the embossed portion of 40% or more than the optical films of Comparative Examples 1 to 14, the embossed shape is good, and the UV adhesiveness is also good. I understand.

  Especially, since the optical film of Example 16 has low acetyl group substitution degree of the cellulose ester in a base material layer, it turns out that a film is hard and becomes brittle and it is easy to tear. In the optical film of Example 21, since the degree of acetyl group substitution of the cellulose ester in the base material layer was too high, the strength of the embossed part was too high, and embossing chipping sometimes occurred. Since the optical film of Example 26 contains a polyester compound containing an aliphatic dicarboxylic acid as a constituent component in the base material layer, it is a surface layer than the optical film of Example 25 containing a polyester compound containing an aromatic dicarboxylic acid as a constituent component. It can be seen that the UV adhesiveness is low because it easily oozes out. In the roll body of Example 42 with a small winding length, it is necessary to frequently replace the roll in the polarizing plate production process; the optical film of Example 49 has a small film conveyance speed at the time of emboss formation. It can be seen that the productivity is slightly low. In the optical film of Example 24, since the SP value of the additive contained in the base material layer is too high, it can be seen that the additive easily oozes into the surface layer and has low UV adhesion. On the other hand, in the optical film of Example 34, since the SP value of the additive is too low, it can be seen that the additive in the base material layer oozes out and the UV adhesiveness deteriorates due to the effect of the oozed additive.

  Since the optical films of Comparative Examples 1 and 4 do not include a layer mainly composed of cellulose ester, it can be seen that the embossed portion has low strength and is easily crushed or chipped. It can be seen that the optical films of Comparative Examples 2 and 3 have low UV adhesion because at least the surface layer contains cellulose ester as a main component. Since the optical film of Comparative Example 5 is too thin, it is easy to break and difficult to handle, and the strength of the embossed portion is low, so that it is easy to be crushed or chipped. Since the optical film of the comparative example 6 is too thick, it turns out that UV adhesiveness is low. This is because when UV light was applied from the optical film side during UV bonding, the energy of the UV light was absorbed by the optical film (mainly the base material layer) and did not reach the bonding interface between the optical film and the polarizer sufficiently. it is conceivable that. It can be seen that in the optical film of Comparative Example 7, the molecular weight of the (meth) acrylic resin in the surface layer is too small, so that the strength of the embossed portion is too low, and crushing and chipping are likely to occur. In the optical film of Comparative Example 8, the haze of the optical film increased because the molecular weight of the (meth) acrylic resin in the surface layer was too large.

  In the optical film of Comparative Example 9, since the transport speed of the film during emboss formation was too high, not only was the strength of the embossed portion low, but the embossed portion could not be formed cleanly. In the optical films of Comparative Examples 10 to 12, since the back roll material used for emboss formation is resin, it is difficult for heat to be transmitted and the embossed portion has low strength. It can be seen that the strength of the embossed portion of the optical film of Comparative Example 13 decreases because the temperature of the embossing roll is low. Since the temperature of the embossing roll is high in the optical film of Comparative Example 14, the embossing is performed in a state where the resin is excessively melted, so that it can be seen that the shape is easily broken. In addition, each layer melted due to the high temperature, and the optical performance also deteriorated.

  ADVANTAGE OF THE INVENTION According to this invention, even if thickness is thin, the optical film which is hard to tear at the time of a process can be provided.

DESCRIPTION OF SYMBOLS 10 Optical film roll body 12 Core 14 Optical film 14A Sample film 15 Stage 16 Embossing part 18A Measuring rod 18B Weight 18 Weight 20 Embossing device 22 Embossing roll 24 Back roll 30 Liquid crystal display device 40 Liquid crystal cell 50 First polarization Plate 52 First polarizer 54 Protective film (F1)
56 Protective film (F2)
60 Second polarizing plate 62 Second polarizer 64 Protective film (F3)
66 Protection Film (F4)
70 Backlight 100 Packaging 110 Roll body 130 Packaging material 130a Inner packaging material 130b Outer packaging material 150a, 150b Sealing member 111 Core 113 Optical film D, D ₀ Height of convex part of embossed part

Claims (16)

A base material layer containing 90% by mass or more of cellulose ester;
They are arranged on both surfaces of the base layer, and two surface layers which contain a weight average molecular weight 50,000 to 1,000,000 and (meth) acrylic resin 90% by mass or more, the optical film thickness 10 to 50 [mu] m, the film A roll of optical film obtained by winding in a direction perpendicular to the width direction,
One end in the width direction of one of the two surface layers of the optical film has an embossed portion,
On the surface of the embossed portion, the height of the convex portion of the embossed portion measured with an initial load of 10 g applied to a circular region having a diameter of 5 mm is D0, and a load of 1 kg is applied to the circular region having a diameter of 5 mm. After being stored for 10 minutes at 23 ° C. and 55% RH in this state, when the height of the convex portion of the embossed portion measured with the 1 kg load applied is D, the crush resistance represented by the following formula The roll body of an optical film whose rate is 40% or more.

  The roll body of the optical film of Claim 1 whose total substitution degree of the acyl group of the said cellulose ester is 2.1 or more and 2.95 or less, and all the said acyl groups are acetyl groups.   The said base material layer is a roll body of the optical film of Claim 1 or 2 which further contains the additive of SP values 9-14.   The roll body of the optical film of Claim 3 whose said additive is a polyester compound which has a repeating unit derived from the polycondensate of diol and dicarboxylic acid.   The polyester compound is a polycondensate of an aliphatic diol having 2 to 4 carbon atoms and a dicarboxylic acid containing an aromatic dicarboxylic acid, or a sealed product in which the molecular terminal of the polycondensate is sealed with an acetyl group. The roll body of the optical film of Claim 4 which exists.   The roll body of the optical film of Claim 3 whose content in the said base material layer of the said additive is 1-20 mass% with respect to the said cellulose ester.   The roll body of the optical film as described in any one of Claims 1-6 whose thickness of the said base material layer exists in the range of 30 to 90% of the total thickness of the said optical film. The winding length of the optical film is less than 1500 m 8000 m, the roll of the optical film according to any one of claims 1-7. It is a manufacturing method of the roll body of the optical film as described in any one of Claims 1-8 ,
Preparing a dope for a base layer containing a cellulose ester and an organic solvent, and a dope for a surface layer containing a (meth) acrylic resin and an organic solvent;
Casting the base layer dope and the surface layer dope while being laminated simultaneously or sequentially on a casting support;
Removing the organic solvent contained in the laminated base layer dope and the surface layer dope to obtain a laminate;
Stretching the laminate to obtain an optical film comprising a base material layer and a surface layer disposed on at least one surface of the base material layer;
And a step of forming embossed portions at both ends in the width direction on the surface layer of the optical film. The method for producing a roll of an optical film according to claim 9 , wherein the stretching of the laminate is performed at a draw ratio of 1.05 to 1.5 times in the width direction of the laminate. The method for producing a roll of an optical film according to claim 9 or 10 , wherein the stretching of the laminate is performed at a draw ratio of 1.01 to 1.5 times in a transport direction of the laminate. The conveying speed of the laminate is a 60～200M / min, the production method of the roll of the optical film according to any one of claims 9-11. A polarizer, said disposed on at least one surface of the polarizer, and an optical film cut out from a roll of an optical film according to any one of claims 1-8, a polarizing plate. The polarizing plate according to claim 13 , wherein the polarizer and the optical film are bonded via an active energy ray-curable adhesive layer. A liquid crystal display device comprising: a liquid crystal cell; and the polarizing plate according to claim 13 or 14 disposed on at least one surface of the liquid crystal cell. The package body containing the roll body of the optical film as described in any one of Claims 1-8 , and the moisture proof sheet which packages the said roll body.

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