KR101302289B1 - Roll of optical film, and method of manufacturing polarizing plate using the same - Google Patents

Abstract

An object of the present invention is to provide an optical film that is hard to be torn at the time of processing even if it is a thin film. It is a roll body of the optical film obtained by winding up the optical film with a thickness of 20-50 micrometers containing a cellulose acetate and an additive with respect to the width direction of a film, and an optical film has an embossing part in the width direction both ends, and The height of the convex portion of the embossed portion before applying the load is referred to as the height of the convex portion of the embossed portion after preserving for 10 minutes at 23 ° C. and 55% RH while applying a 1 kg load to a 5 mm diameter circular area on the surface of the embossed portion. When D ₀ , the breakdown resistance represented by the following formula (1) is 30% or more, and the residual amount of methanol in the optical film is 10 to 100 ppm by mass relative to the optical film, and ethanol in the optical film. And more than any residual amount in butanol.
&Quot; (1) "
Fracture Resistance (%) = D / D ₀ × 100

Description

Roll body of optical film and manufacturing method of polarizing plate using same {ROLL OF OPTICAL FILM, AND METHOD OF MANUFACTURING POLARIZING PLATE USING THE SAME}

This invention relates to the roll body of an optical film, and the manufacturing method of the polarizing plate using the same.

In recent years, thinning of liquid crystal displays is required. The liquid crystal display device usually has a liquid crystal cell, a pair of polarizing plates sandwiching it, and a backlight. A polarizing plate has a polarizer and a pair of protective film which clamps it. And thin film formation is calculated | required further by the protective film which is a structural member of a liquid crystal display device.

As a protective film, the film containing cellulose acetate is proposed (for example, refer patent documents 1-3).

Such a protective film is normally stored as a roll body wound in the longitudinal direction. Therefore, in order to suppress adhesion of protective films, etc., while saving the roll body of a protective film, the embossing process is normally given to the width direction both ends of a protective film (for example, refer patent document 4).

Japanese Patent Laid-Open No. 2011-127046 Japanese Patent Laid-Open No. 2011-137860 Japanese Patent Laid-Open No. 2011-105924 Japanese Patent Laid-Open No. 2002-122741

However, after preserving the roll body of a protective film under fixed conditions, when a process is performed, such as unwinding a protective film, cutting it to a predetermined | prescribed magnitude | size, or apply | coating the coating liquid for hard-coat layers, a problem that a protective film is easy to tear. There was.

MEANS TO SOLVE THE PROBLEM The present inventors discovered that one of the reasons which a protective film becomes easy to tear is that the embossing part of the width direction both ends of a protective film breaks, while preserving the roll body of a protective film. In other words, when the embossed portion of the protective film is broken, the protective films to be laminated are easily in contact with each other; In the adhesion part of protective films, the additive (plasticizer etc.) contained in a protective film becomes easy to be bleeded out. As a result, in the protective film, a portion with a relatively high density and a portion with a relatively low portion occur; It is thought that a protective film becomes easy to tear at the time of processing of a protective film. In addition, the bleeding of the additive was more likely to occur in the film having a thin film thickness, and the protective film was more likely to be torn.

Breakage of the embossed portion was particularly likely to occur in a protective film having a thin film thickness or a protective film in which the embossed portion was formed while being conveyed at high speed.

This invention is made | formed in view of the said situation, Comprising: Even if thickness is thin, it aims at providing the optical film which is hard to tear at the time of processing.

[1] A roll body of an optical film obtained by winding an optical film having a thickness of 20 to 50 µm containing cellulose acetate and an additive in a direction perpendicular to the width direction of the film, wherein the optical film has embossed portions at both ends in the width direction, The height of the convex part of the said embossed part after storing for 10 minutes at 23 degreeC 55% RH on the surface of the said embossed part of the said optical film in the state which applied a 1 kg load to a 5 mm diameter circular area | region is called D, and before applying the said load. When the height of the convex portion of the embossed portion is D ₀ , the fracture resistance represented by the following Equation 1 is 30% or more,

&Quot; (1) "

Fracture Resistance (%) = D / D ₀ × 100

The roll body of the optical film whose residual amount of methanol in the said optical film is 10-100 mass ppm with respect to the said optical film, and is more than any residual amount of ethanol and butanol in the said optical film.

[2] The roll body of optical film according to the above [1], wherein the total substitution degree of the acetyl group of the cellulose acetate is 2.3 or more and 2.95 or less.

[3] The roll body of the optical film according to the above [1] or [2], wherein the winding length of the optical film is 1000 m or more and 8000 m or less.

[4] The roll body of optical film according to any one of [1] to [3], wherein the additive is a plasticizer having an SP value of 9 to 11.

[5] The roll body of optical film according to the above [4], wherein the plasticizer is triphenyl phosphate, ethyl phthalyl ethyl glycolate or a polyester compound.

[6] The molecular terminal of the compound according to the above [5], wherein the polyester compound is obtained by reacting a diol having 1 to 4 carbon atoms with a dicarboxylic acid containing at least an aromatic dicarboxylic acid. The roll body of the optical film which capped further with the group.

[7] The roll body of the optical film according to any one of [1] to [6], wherein the content of the plasticizer is 1 to 20% by mass with respect to the cellulose acetate.

[8] A step of removing the embossed portion of the optical film in the roll body of the optical film according to any one of the above [1] to [7], and a step of bonding the optical film and the polarizer from which the embossed portion is removed. The manufacturing method of the polarizing plate which has.

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

1: is a schematic diagram which shows an example of the roll body of an optical film.
2 is a partial cross-sectional view showing an example of the vicinity of an embossed portion of an optical film.
3 is a partial cross-sectional view showing an example of an embossed portion in the measurement of the fracture resistance.
It is a schematic diagram which shows an example of the measuring method of the fracture resistance of the convex part of an embossed part.
It is a schematic diagram which shows an example of an embossing processing apparatus.
It is a schematic diagram which shows an example of a structure of a liquid crystal display device.

1. Roll body of optical film

The roll body of the optical film of this invention is obtained by winding up an elongate optical film in the longitudinal direction (perpendicular direction with respect to the width direction of a film).

1: is a schematic diagram which shows an example of the roll body of an optical film. As shown in FIG. 1, the roll body 10 of an optical film has the winding core 12 and the elongate optical film 14 wound around the longitudinal direction of a film around it. And in order to suppress adhesion of the optical films 14 laminated | stacked by the roll body 10, the embossing part 16 is formed in the width direction both ends of the elongate optical film 14. As shown in FIG.

2 is a cross-sectional view illustrating an example of the vicinity of an embossed portion of an optical film. As shown in FIG. 2, the height D ₀ of the convex part 16A which comprises the embossing part 16 becomes like this. Preferably it is 1.0 micrometer or more and 10.0 micrometer or less, More preferably, it is 2.0 micrometer or more and 6.0 micrometer or less. The height D ₀ of the convex portion 16A means the height from the film surface F (the film surface of the portion where the embossing is not formed) to the apex of the convex portion 16A. When the height of the convex portion 16A is less than 1.0 µm, the optical films tend to be in close contact with each other, which is not preferable. On the other hand, when the height of the convex part 16A is too high, the width direction center part of a roll body will bend easily, and planarity as an optical film is hard to be maintained.

The width w of the convex portion 16A can be about 0.05 to 5 mm. The width w of the convex portion 16A is expressed as a distance between two points at which the convex portion 16A intersects the film surface F in the cross section of the embossed portion 16. It is preferable that it is 0.1-5 mm, and, as for the space | interval b of 16 A of convex parts 16A, it is more preferable that it is 0.5-2 mm. The space | interval b of 16 A of convex parts and 16 A of convex parts is represented by the distance between the points which two convex parts 16A intersect film surface F in the cross section of the embossing part 16, respectively.

It is preferable that the width W of the embossing part 16 is 0.12 to 2.1% of range with respect to the width of an optical film. Specifically, the width W of the embossed portion 16 is set to 5 to 25 mm, depending on the size of the width of the optical film; Preferably it is 10-20 mm. If the width W of the embossing part 16 is too big | large, the area which can be used as an optical film will become small. On the other hand, when the width W of the embossing part 16 is too small, it is easy to adhere | attach optical films.

In the roll body of an optical film, it is easy to destroy by the weight of the optical film in which the convex part of the embossed part of the optical film of the winding core vicinity is laminated | stacked. When the convex part of the embossing part is broken, the optical films to be laminated are easily in contact with each other; In the contact | adherence part of optical films, the bleeding of the additive (for example, a plasticizer) contained in an optical film is easy to generate | occur | produce. When bleeding of the additive occurs in the close contact portion between the optical films, coarse and dense portions of the additive (for example, a plasticizer) are generated in the optical film, which is likely to be torn when the optical film is processed.

The breakage of the convex portion of such an embossed portion is particularly likely to occur when the film thickness of the optical film is made thin or the embossing process is carried out while conveying the optical film at high speed. In particular, since the formation time of an embossed part is short, the embossed part formed while conveying an optical film at high speed tends to lower the intensity | strength of an embossed part.

Therefore, even if a force is applied to the embossed portion of the optical film, the convex portion of the embossed portion is hard to be broken; That is, it is preferable that the embossing portion has a high strength (high elastic modulus). Specifically, the breakdown resistance of the convex portion of the embossed portion measured by the following method is preferably 30% or more, and more preferably 50% or more.

The fracture resistance of the convex portion of the embossed portion can be measured by the following method. 3 and 4 are partial cross-sectional views showing an example of a method for measuring the fracture resistance of the convex portion of the embossed portion.

1) The area | region containing the embossing part 16 of the optical film 14 is cut out, and the sample film 14A is obtained (refer FIG. 4). Then, the (D ₀ height of the convex portion prior to applying the load in Fig. 3) convex portions of the height D ₀ of the embossment 16 of the sample film (14A) is measured with a thickness meter.

2) Next, as shown in FIG. 4, the sample film 14A is disposed on the stage 15. And the weight 18 of 1 kg in total consisting of 18A of metal cylindrical rods 18A of diameter 5mm mounted perpendicularly to the film surface, and the weight 18B arrange | positioned on it is put. In this way, it preserve | saves for 10 minutes under 23 degreeC 55% RH in the state which applied the load of 1 kg to the original area | region of 5 mm diameter on the surface of the embossing part 16. Then, the height D (the height D of the convex part after applying the load in FIG. 3) of the convex part of the embossing part 16 when a load is removed (the weight is removed) is measured with a thickness meter.

3) The fracture resistance is calculated by applying the height D ₀ of the convex portion before applying the load measured in the above 1) and the height D of the convex portion after applying the load measured in the above 2) to the following formula (1).

&Quot; (1) "

Fracture Resistance (%) = D / D ₀ × 100

Adjustment of the fracture resistance of the convex part of an embossed part is embossing processing condition; It can be adjusted by various combinations of at least two or more of 1) the surface temperature of the embossing roll, 2) the surface temperature of the back roll, 3) the roll diameter of the embossing roll and 4) the material of the back roll. Especially, it is preferable to adjust 1) the surface temperature of an embossing roll, and 2) the surface temperature of a back roll; 3) it is more preferable to adjust the embossing roll diameter; 4) It is particularly preferable to select the material of the back roll. In order to raise the fracture resistance of the convex part of an embossing part, it is preferable to make 1) the surface temperature of an embossing roll high, and 2) make the surface temperature of a back roll high.

The bleeding of the additive in the close contact portions of the optical films described above is likely to occur due to the movement of the additive in the film of the optical film, and the movement of the additive in the film of the optical film is caused by the solvent remaining in the film. It is easy to be promoted by Therefore, in order to suppress the bleeding of the additive in the adhesive part of optical films, the content rate of methanol which has low affinity with an additive among the solvent remaining in the film | membrane of an optical film has affinity with an additive. Less than high ethanol or butanol is preferable.

Therefore, it is preferable that the quantity (mass) of methanol which remains in the optical film which comprises a roll body is larger than the quantity (mass) of ethanol or butanol. The amount of methanol remaining in the optical film is preferably 10 to 100 mass ppm, more preferably 10 to 80 mass ppm, still more preferably 20 to 60 mass ppm with respect to the film.

The amount (mass) of methanol remaining in the optical film constituting the roll body is the solvent composition contained in the dope when the optical film is produced by the solution casting method as described later, and the drying temperature and drying time of the film after stretching. And so on.

The quantity of the solvent which remains in the optical film which comprises a roll body can be measured by the following method.

1) Construction of calibration curve

The sample whose known concentration of the solvent to be measured is known is placed in a dedicated vial bottle, sealed with a septum and an aluminum cap, and set in a headspace sampler. Subsequently, the vial bottle is heated under the following headspace heating conditions to generate a volatile component, and the obtained volatile component is measured by gas chromatography. The same measurement is performed about the sample from which the density | concentration of a solvent differs. The peak area of the solvent in the GC chart obtained by each measurement is calculated, a plot of the concentration of the solvent and the peak area is produced to obtain a calibration curve.

(Headspace sampler)

Instrument: Hewlett-Packard, Inc. headspace sampler HP7694

Headspace heating conditions: 20 minutes at 120 ° C

(Gas chromatography)

A device: Hewlett-Packard Corporation type 5971

Column: J & W Corporation DB-624

Detector: Hydrogen Ionization Detector (FID)

GC temperature rising condition: After holding for 3 minutes at 45 degreeC, it heated up to 100 degreeC at 8 degreeC / min.

GC introduction temperature: 150 ℃

2) Measurement of Solvent Residue in Optical Film

The film cut out by 10 cm in width and width was cut into finely about 5 mm, and sealed in a dedicated vial bottle in the same manner as in 1) above, followed by heat treatment under headspace heating conditions, and the obtained volatile component was measured by gas chromatography.

3) Calculation of Solvent Amount

The peak area of a solvent is computed from the obtained GC chart, and the quantity of the solvent which remains in a film is calculated | required in contrast with the calibration curve obtained by said 1). The quantity of the solvent remaining in a film is calculated | required as mass ratio (mass%) with respect to the whole film.

The winding length of the optical film in the roll body of this invention is 1000 m or more and 8000 m or less normally, Preferably they are 3800 m or more and 6000 m or less. The diameter of the winding core in the roll body of this invention can be about 100 mm-250 mm. The width of the optical film in the roll of the optical film 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 the high embossing part in the width direction both ends of an optical film. Therefore, also in the roll body of the optical film with a long winding length, the convex part of the embossed part of the optical film of the winding core vicinity can be made to be hard to be destroyed by the weight of the optical film laminated | stacked. Therefore, adhesion of optical films to each other; And it can suppress the bleeding of the additive by it, and can suppress that a film tears at the time of film processing.

In addition, in the roll body of this invention, the quantity of methanol which remains in an optical film is adjusted to the predetermined range. Therefore, even if it breaks by the weight of the optical film in which the convex part of an embossing part is laminated | stacked, the movement of the additive in the film | membrane of an optical film can be suppressed. Thereby, the bleeding of the additive in the adhesion part of optical films with a roll chain is suppressed; It can suppress that a film tears at the time of film processing.

2. Composition and Physical Properties of Optical Film

The optical film contains a cellulose ester and an additive.

About cellulose ester

A cellulose ester is a compound obtained by esterifying the hydroxyl group of a cellulose by aliphatic carboxylic acid or aromatic carboxylic acid.

The acyl group contained in a cellulose ester is an aliphatic acyl group or an aromatic acyl group, Preferably it is an aliphatic acyl group. Especially, in order to acquire fixed phase retardation expression, a C2-C6 aliphatic acyl group is preferable, and a C2-C4 aliphatic acyl group is more preferable. Examples of the aliphatic acyl group having 2 to 4 carbon atoms include an acetyl group, propionyl group, butanoyl group and the like, and more preferably an acetyl group.

Examples of the cellulose esters include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, and the like, and preferably cellulose acetate. It is preferable that all the acyl groups contained in a cellulose ester of an cellulose acetate are an acetyl group.

The acetyl group substitution degree (total substitution degree of acyl group) of cellulose acetate is high in heat resistance, high in solubility in a solvent, and relatively easy to form, and therefore it is preferably 2.3 or more and 2.95 or less, more preferably 2.5 or more. 2.95 or less, More preferably, they are 2.8 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.

It is preferable that it is 3.0 * 10 <^4> or more and less than 2.0 * 10 <^5> , and, as for the number average molecular weight of a cellulose acetate, it is more preferable that it is 4.5 * 10 <^4> or more and less than 1.5 * 10 <^5> . It is preferable that it is 1.2 * 10 <^5> or more and less than 2.5 * 10 <^5> , and, as for the weight average molecular weight of cellulose acetate, it is more preferable that it is 1.5 * 10 <^5> or more and less than 2.0 * 10 <^5> .

It is preferable that the molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of a cellulose acetate is 1.0-4.5.

The number average molecular weight and the weight average molecular weight of cellulose acetate can be measured by gel permeation chromatography (GPC).

Measurement conditions are as follows.

Solvent: methylene chloride

Column: Three Shodex K806, K805, and K803G (manufactured by Showa Denko Co., Ltd.) are used in connection.

Column temperature: 25 ° C

Sample concentration: 0.1% by mass

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (made by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0 ml / min

Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 1.0 × 10 ⁶ to 5.0 × 10 ^{2 A} calibration curve with 13 samples is used. 13 samples are preferably selected at substantially equal intervals.

A cellulose ester can be synthesize | combined by a well-known method. Specifically, cellulose can be synthesized by esterifying an organic acid having 3 or more carbon atoms or an anhydride thereof containing at least acetic acid or acetic anhydride (see Japanese Patent Laid-Open No. Hei 10-45804). ).

Examples of cellulose which is a raw material of cellulose acetate include cotton linter, wood pulp (derived from hardwood and hardwood), kenaf and the like. 1 type of cellulose used as a raw material may be sufficient, and 2 or more types of mixtures may be sufficient as it.

About additive

Examples of the additive included in the optical film include a plasticizer, an antioxidant, a light stabilizer, an ultraviolet absorber, a retardation regulator, an antistatic agent, a release agent, and the like, and preferably a plasticizer.

Examples of plasticizers include polyester compounds, polyhydric alcohol ester compounds, polyhydric carboxylic acid ester compounds (including phthalic acid ester compounds), glycolate compounds and ester compounds (including fatty acid ester compounds and phosphate ester compounds, etc.) do. These may be used independently and may be used in combination of 2 or more type.

A polyester compound is a compound containing the repeating unit obtained by making dicarboxylic acid and diol react.

The dicarboxylic acid which comprises a polyester compound is aromatic dicarboxylic acid, aliphatic dicarboxylic acid, or alicyclic dicarboxylic acid, Preferably it is aromatic dicarboxylic acid. 1 type may be sufficient as dicarboxylic acid, and 2 or more types of mixtures may be sufficient as it.

The diol constituting the polyester compound is an aromatic diol, an aliphatic diol or an alicyclic diol, preferably an aliphatic diol, and more preferably a diol having 1 to 4 carbon atoms. The diol may be one kind or a mixture of two or more kinds.

Especially, it is preferable that a polyester compound contains the repeating unit obtained by making at least dicarboxylic acid containing aromatic dicarboxylic acid react with C1-C4 diol; It is more preferable to include the repeating unit obtained by making dicarboxylic acid containing aromatic dicarboxylic acid and aliphatic dicarboxylic acid, and C1-C4 diol react.

Although both ends of the molecule | numerator of a polyester compound may be capped and it may not be capped, it is preferable that it is capped from a viewpoint of reducing the moisture permeability of a film.

It is preferable that a polyester compound is a compound represented by General formula (1) or (2). In the following general formula, n is an integer of 1 or more.

&Lt; General Formula 1 &

B- (G-A) n-G-B

&Lt; General Formula 2 &

C- (A-G) n-A-C

A of General Formulas 1 and 2 is a divalent group derived from an alkylenedicarboxylic acid having 3 to 20 (preferably 4 to 12) carbon atoms, and 4 to 20 (preferably 4 to 12 carbon atoms) Or a divalent group derived from an alkenylenedicarboxylic acid of) or an aryldicarboxylic acid having 8 to 20 (preferably 8 to 12) carbon atoms.

Examples of divalent groups derived from alkylenedicarboxylic acids having 3 to 20 carbon atoms in A include 1,2-ethanedicarboxylic acid (succinic acid) and 1,3-propanedicarboxylic acid ( Derived from glutaric acid), 1,4-butanedicarboxylic acid (adipic acid), 1,5-pentanedicarboxylic acid (pimelic acid), 1,8-octanedicarboxylic acid (sebacic acid), and the like Divalent groups are included. Examples of the divalent group derived from alkenylenedicarboxylic acid having 4 to 20 carbon atoms in A include divalent groups derived from maleic acid, fumaric acid and the like. Examples of the divalent group derived from aryldicarboxylic acid having 8 to 20 carbon atoms in A include 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid, 1 Divalent groups derived from naphthalenedicarboxylic acids such as, 4-benzenedicarboxylic acid and 1,5-naphthalenedicarboxylic acid.

1 type may be sufficient as A and 2 or more types may be combined. Among them, A is preferably a combination of alkylenedicarboxylic acid having 4 to 12 carbon atoms and aryldicarboxylic acid having 8 to 12 carbon atoms.

G in General Formulas 1 and 2 is a divalent group derived from alkylene glycol having 2 to 20 carbon atoms (preferably 2 to 12), and aryl having 6 to 20 carbon atoms (preferably 6 to 12). Divalent groups derived from glycols or divalent groups derived from oxyalkylene glycols having 4 to 20 (preferably 4 to 12) carbon atoms.

Examples of the divalent group derived from alkylene glycol having 2 to 20 carbon atoms in G 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-propanediol (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 Divalent groups derived from, 8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol and the like.

Examples of the divalent group derived from aryl glycol having 6 to 20 carbon atoms in G include 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), Divalent groups derived from 1,4-dihydroxybenzene (hydroquinone) and the like. Examples of the divalent group derived from oxyalkylene glycol having 4 to 12 carbon atoms in G include divalent glycol derived from diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and the like. Groups are included.

One type of G may be sufficient and 2 or more types may be combined. Especially, it is preferable that G is a C2-C12 alkylene glycol.

B of General formula 1 is a monovalent group derived from an aromatic ring containing monocarboxylic acid or aliphatic monocarboxylic acid.

The aromatic ring-containing monocarboxylic acid in the monovalent group derived from the aromatic ring-containing monocarboxylic acid is a carboxylic acid containing an aromatic ring in a molecule, and not only the aromatic ring is directly bonded to a carboxyl group, but the aromatic ring is an alkylene group or the like. It also includes a carboxyl group bonded through. Examples of monovalent groups derived from an aromatic ring-containing monocarboxylic acid include benzoic acid, parabutyl benzoic acid, orthotoluic acid, metatoluic acid, paratoluic acid, dimethylbenzoic acid, ethylbenzoic acid, normalpropylbenzoic acid, aminobenzoic acid, Monovalent groups derived from acetoxybenzoic acid, phenylacetic acid, 3-phenylpropionic acid, and the like.

Examples of monovalent groups derived from aliphatic monocarboxylic acids include monovalent groups derived from acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid and the like. Among them, monovalent groups derived from alkylmonocarboxylic acids having 1 to 3 carbon atoms in the alkyl moiety are preferred, and acetyl groups (monovalent groups derived from acetic acid) are more preferred.

C in Formula 2 is a monovalent group derived from an aromatic ring-containing monoalcohol or an aliphatic monoalcohol.

The aromatic ring-containing monoalcohol is an alcohol containing an aromatic ring in the molecule, and includes not only the aromatic ring directly bonded to the OH group, but also the aromatic ring bonded to the OH group through an alkylene group or the like. Examples of the monovalent group derived from an aromatic ring-containing monoalcohol include monovalent groups derived from benzyl alcohol, 3-phenylpropanol and the like.

Examples of monovalent groups derived from aliphatic monoalcohols include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol, hexanol, isohexanol, cyclohexyl alcohol, octanol, isooctanol, Monovalent groups derived from 2-ethylhexyl alcohol, nonyl alcohol, isononyl alcohol, tert-nonyl alcohol, decanol, dodecanol, dodecahexanol, dodecaoctanol, allyl alcohol, oleyl alcohol and the like. Among these, monovalent groups derived from alcohols having 1 to 3 carbon atoms such as methanol, ethanol, propanol and isopropanol are preferable.

It is preferable that it is 300-1500, and, as for the weight average molecular weight of a polyester compound, it is more preferable that it is 400-1000. The polyester compound whose weight average molecular weight is less than 300 may be easy to be protruded from an optical film.

Specific examples of the polyester compound are shown below. First, the specific example of the polyester compound which capped both ends by the "aromatic group" is shown.

Next, the specific example of the polyester compound which capped both ends by the "aliphatic group" is shown below.

P-1: The acetyl esterified body of both ends of the condensate (weight average molecular weight 950) which consists of adipic acid / phthalic acid / ethanediol (1/1/2 molar ratio)

P-2: The acetyl esterified body of both ends of the condensate (weight average molecular weight 2500) which consists of succinic acid / phthalic acid / ethanediol / (1/1/2 molar ratio)

P-3: The acetyl esterified body of both ends of the condensate (weight average molecular weight 1300) which consists of glutaric acid / isophthalic acid / 1, 3- propanediol (1/1/2 molar ratio)

P-4: Condensate (water) consisting of succinic acid / glutaric acid / adipic acid / terephthalic acid / isophthalic acid / ethanediol / 1,2-propanediol (1/1/1/1/1/3/2 molar ratio) Propyl ester on both ends of average molecular weight 3000)

P-5: Butyl esterified compound of both ends of condensate (weight average molecular weight 2100) which consists of succinic acid / phthalic acid / ethanediol / (1/1/2 molar ratio)

P-6: 2-ethylhexyl esterified compound of both ends of the condensate (number average molecular weight 2500) which consists of adipic acid / terephthalic acid / 1, 2- propanediol (1/1/2 molar ratio)

P-7: 2- at both ends of a condensate (weight average molecular weight 3500) consisting of succinic acid / terephthalic acid / poly (average degree of polymerization 5) propylene ether glycol / 1,2-propanediol (2/1/1/2 molar ratio) Ethylhexyl ester

The polyhydric alcohol ester compound is an ester compound (alcohol ester) of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably a 2 to 20 valent aliphatic polyhydric alcohol ester. It is preferable that a polyhydric alcohol ester compound has an aromatic ring or a cycloalkyl ring in a molecule | numerator.

Preferred examples of the aliphatic polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, and 1,2-butanediol. , 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, trimethylolpropane, Pentaerythritol, trimethylolethane, xylitol and the like. Especially, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylol propane, xylitol, etc. are preferable.

The monocarboxylic acid is not particularly limited and may be aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, or the like. In order to improve the moisture permeability of a film and to make it hard to volatilize, an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferable. 1 type may be sufficient as a monocarboxylic acid, and 2 or more types of mixtures may be sufficient as it. Moreover, all of the OH groups contained in aliphatic polyhydric alcohol may be esterified and a part may be left as OH group.

The aliphatic monocarboxylic acid is preferably a fatty acid having a straight or branched chain having 1 to 32 carbon atoms. Carbon number of aliphatic monocarboxylic acid becomes like this. More preferably, it is 1-20, More preferably, it is 1-10. Examples of aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelagonic acid, capric acid, 2-ethyl-hexanoic acid, undecyl acid, lauric acid, tri Decylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachinic acid, behenic acid, lignoseric acid, sertoic acid, heptaconic acid, montanic acid, melisic acid Saturated fatty acids such as lactic acid; Unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, and the like. Especially, in order to improve compatibility with cellulose acetate, an acetic acid or a mixture of acetic acid and other monocarboxylic acids is preferable.

Cyclopentanecarboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, etc. are contained in the example of alicyclic monocarboxylic acid.

Examples of the aromatic monocarboxylic acid include benzoic acid; One to three alkyl groups or alkoxy groups (for example, methoxy or ethoxy groups) are introduced into the benzene ring of benzoic acid (for example, toluic acid); Aromatic monocarboxylic acids (for example, biphenyl carboxylic acid, naphthalene carboxylic acid, tetralin carboxylic acid, etc.) which have two or more benzene rings are contained, Preferably it is benzoic acid.

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

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

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

Examples of the polyvalent carboxylic acid include trivalent or more aromatic polyvalent carboxylic acids or derivatives thereof such as trimellitic acid, trimesic acid and pyromellitic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid and maleic acid. Acids, aliphatic polyhydric carboxylic acids such as tetrahydrophthalic acid, tartaric acid, tartronic acid, malic acid, oxy polyvalent carboxylic acids such as citric acid, and the like, and oxy polyhydric carboxylic acids are preferred in order to suppress volatilization from the film.

Examples of the alcohol compound include an aliphatic saturated alcohol compound having a straight or branched chain, an aliphatic unsaturated alcohol compound having a straight or branched 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, cinnamil alcohol, and the like.

Although the molecular weight of a polyhydric carboxylic acid ester compound does not have a restriction | limiting in particular, It is preferable that it is 300-1000, and it is more preferable that it is 350-750. As for the molecular weight of a polyhydric carboxylic acid ester plasticizer, a larger one is preferable from a viewpoint of suppressing bleed out; The smaller one is preferable from the viewpoint of moisture permeability and compatibility with cellulose acetate.

Examples of the polyhydric carboxylic acid ester compound include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyltributyl citrate, acetyl triphenyl citrate, Acetyl tribenzyl citrate, dibutyl tartarate, diacetyl dibutyl tartarate, tributyl trimellitic acid, tetrabutyl pyromellitic acid and the like.

A phthalic acid ester compound may be sufficient as a polyhydric carboxylic acid ester compound. Examples of the phthalic acid ester 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. This includes.

Examples of the glycolate compound include alkylphthalylalkyl 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 glycol 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 , Butylphthalyl 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 citric acid ester compound, a phosphate ester compound and the like.

Examples of the fatty acid ester compounds include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate and the like. Examples of the citric acid ester compound include acetyl trimethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate and the like. Examples of the phosphoric acid ester compound include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, biphenyl diphenyl phosphate, trioctyl phosphate and tributyl phosphate, and preferably triphenyl phosphate. All.

Especially, a polyester compound, a glycolate compound, and a phosphate ester compound are preferable, and a polyester compound, ethyl phthalyl ethyl glycolate, and triphenyl phosphate are more preferable.

In order to increase the compatibility between the plasticizer and the cellulose ester, the solubility parameter (SP value) of the fedor of the plasticizer is preferably in the range close to that of the cellulose ester, specifically, in the range of 9 to 11 It is more preferable.

The SP value in this invention can be calculated | required by calculation using the parameter of Fedor. The unit of the SP value is a 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. Fedor's parameters are described in the references (p54-57 of Harada Yujima Makita Shoten, 1977).

Content of a plasticizer becomes like this. Preferably it is 1-20 mass% with respect to a cellulose acetate, More preferably, it is 1.5-15 mass%. When content of a plasticizer is less than 1 mass%, the plasticizer provision effect may not be enough. On the other hand, when content of a plasticizer is more than 20 mass%, a plasticizer will come out easily in an optical film.

Particles (made of mat)

An optical film may further contain microparticles | fine-particles (mat agent) as needed for the reason of improving the slipperiness of a surface.

The fine particles may be inorganic fine particles or organic fine particles. Examples of the 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, magnesium silicate and calcium phosphate Etc. are included. Especially, silicon dioxide and zirconium oxide are preferable, and in order to reduce the increase of the haze of the film obtained, it is more preferable silicon dioxide.

Examples of the fine particles of silicon dioxide include aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (above Nippon Aerosil Co., Ltd.), sea host KE-P10, KE- P30, KE-P50, KE-P100 (above Nippon Shokubai Co., Ltd. product) etc. are contained. Especially, since a friction coefficient can be reduced, aerosil R972V, NAX50, Sea host Star KE-P30, etc. can be reduced, and it is especially preferable.

It is preferable that it is 5-50 nm, and, as for the primary particle diameter of microparticles | fine-particles, it is more preferable that it is 7-20 nm. Although the effect of improving the slipperiness | lubricacy of the film from which the larger primary particle diameter is obtained is large, transparency falls easily. 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 secondary aggregates of the fine particles is observed by a transmission electron microscope at a magnification of 500,000 to 2 million times, and the primary particles or secondary aggregates are observed, and as the average value of the particle diameters of 100 primary particles or 100 secondary particles. You can get it.

It is preferable that it is 0.05-1.0 mass% with respect to the whole cellulose acetate containing a low substitution component, and, as for content of microparticles | fine-particles, it is more preferable that it is 0.1-0.8 mass%.

Physical Properties of Optical Film

The thickness of the optical film is preferably 200 µm or less, more preferably 100 µm or less, still more preferably 50 µm or less, for the reason of reducing variation in retardation due to heat or humidity, and particularly. Preferably it is 35 micrometers. On the other hand, in order to obtain the film strength and retardation which can function as a protective film, the thickness of an optical film becomes like this. Preferably it is 10 micrometers or more, More preferably, it is 20 micrometers or more. Especially, it is preferable that the thickness of an optical film is 20-50 micrometers.

When an optical film is a protective film which does not have a phase difference adjustment function, it is preferable that retardation Ro of the in-plane direction measured at wavelength 590nm is 0 nm or more and 30 nm or less, and is 0 nm or more and 10 nm or less in the environment of 23 degreeC and 55% RH. More preferred. It is preferable that they are 0 nm or more and 70 m or less, and, as for the retardation Rth of a thickness direction, it is more preferable that they are 0 nm or more and 50 nm or less.

Retardation Ro and Rth are respectively defined with the following formula | equation.

&Lt; EMI ID =

R ₀ = (nx-ny) × d

<Equation II>

Rth = {(nx + ny) / 2-nz} xd

(nx: refractive index in the slow axis direction x in the film plane, ny: refractive index in the direction y orthogonal to the slow axis direction x in the film plane, nz: refractive index in the thickness direction z of the film, d: thickness of the film (nm ))

The retardation R ₀ and Rth may be, for example, be measured by the following method.

1) The optical film is moistened with 23 ° C. and 55% RH. The average refractive index of the optical film after humidity control is measured with an Abbe refractometer or the like.

2) Measure the R ₀ of sikyeoteul when measured parallel to the incident wavelength 590nm of the light to the normal of the film surface after the humidity in the art for an optical film Cobra (KOBRA) 21ADH, not Gay sokku Ltd.

3) Cobra (KOBRA) 21ADH uses a slow axis in the plane of the optical film as an inclination axis (rotation axis), and enters light having a measurement wavelength of 590 nm from an angle of θ (incidence angle (θ)) with respect to the normal of the surface of the optical film. The retardation value R (θ) at the time of making it measure is measured. The measurement of retardation value R ((theta)) can be performed 6 points every 10 degrees in the range of 0 degrees-50 degrees. The in-plane slow axis of the optical film can be confirmed by KOBRA 21ADH.

4) From the measured R ₀ and R (θ), the above-described average refractive index and the film thickness, nx, ny and nz are calculated by KOBRA 21ADH to calculate Rth at the measurement wavelength of 590 nm. The retardation can be measured under 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 measurement of the orientation angle (theta) 1 of an optical film can be measured using automatic birefringence cobra (KOBRA) -WR (Oji Keisukuki).

It is preferable that the internal haze measured based on JISK-7136 of an optical film is 0.01-0.1. It is preferable that it is 90% or more, and, as for the visible light transmittance of an optical film, it is more preferable that it is 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. Antireflection films, antiglare films, hard coat films and the like.

2. Manufacturing method of roll body of optical film

The roll body of the optical film of the present invention comprises: 1) a step of dissolving at least cellulose acetate and an additive in a solvent to prepare a dope; 2) a step of casting a dope onto an endless metal support; and 3) a flexible dope. E) evaporating the solvent to obtain a web; 4) peeling the web from the metal support; 5) stretching the web after drying; obtaining a film; 6) embossing the both ends of the film in the width direction; ) It can obtain through the process of winding up a film.

1) Process of manufacturing dope

In a melting kiln, cellulose acetate and additives are dissolved in a solvent to prepare dope.

The solvent contained in dope may be one type, or may combine 2 or more types. It is preferable to use combining the good solvent of a cellulose acetate and a poor solvent from a viewpoint of improving production efficiency. A good solvent means the solvent which melt | dissolves a cellulose acetate alone, and a poor solvent means what swells a cellulose acetate or does not melt | dissolve alone. Therefore, the good solvent and the poor solvent differ depending on the average acyl group substitution degree (acetyl group substitution degree) of cellulose acetate.

Examples of the good solvent include organic halogen compounds such as dichloromethane, dioxolane, acetone, methyl acetate, methyl acetoacetate, and the like, and preferably dichloromethane or methyl acetate.

Examples of the poor solvent include methanol (SP value 14.5), ethanol (SP value 12.7), n-butanol (SP value 11.4), cyclohexane, cyclohexanone and the like. In order to suppress the bleeding of the additive in the optical film which comprises a roll body, it is a poor solvent with low affinity with an additive; That is, the poor solvent with a large absolute value of the difference with SP value of an additive is preferable, and methanol is preferable.

The poor solvent may be one kind or a mixture of two or more kinds. When a poor solvent is a mixture of 2 or more types of poor solvents, it is preferable that the content rate of the poor solvent with a large absolute value of the difference with SP value of an additive is the largest.

When using in combination a good solvent and a poor solvent, in order to improve the solubility of a cellulose acetate, it is preferable that there are more good solvents than a poor solvent. It is preferable that the mixture ratio of a good solvent and a poor solvent is 70-98 mass%, and a poor solvent is 2-30 mass%.

The higher the concentration of the cellulose acetate in the dope is, in order to reduce the dry load, but the higher the concentration of the cellulose acetate, the more difficult the filtration. Therefore, the concentration of cellulose acetate in the dope is preferably 10 to 35 mass%, and more preferably 15 to 25 mass%.

The method for dissolving the cellulose acetate in the solvent may be, for example, a method of dissolving under heating and pressure, a method of adding a poor solvent to the cellulose acetate and swelling, followed by further adding a good solvent to dissolve, and a cooling dissolution method.

Especially, since it can heat above the boiling point in normal pressure, the method of melt | dissolving under heating and pressurization is preferable. Specifically, when stirring and dissolving while heating to a temperature in the range not lower than the boiling point of the solvent under normal pressure and not causing the solvent to boil under pressure, it is possible to suppress the generation of bulky debris called gels or lumps.

Although the higher one is preferable from the viewpoint of raising the solubility of a cellulose acetate, when heating temperature is high, it is necessary to raise a pressure and productivity will fall. For this reason, it is preferable that heating temperature is 45-120 degreeC, 60-110 degreeC is more preferable, It is still more preferable that it is 70 degreeC-105 degreeC.

The resultant dope may contain, for example, insoluble matter such as impurities contained in cellulose acetate as a raw material. Such insoluble matters may be bright spot foreign materials in the resulting film. In order to remove such an insoluble matter, it is preferable to filter the obtained dope further.

2) Process of casting dope on endless metal support

The dope is cast from an slit of the press die onto an endless metal support (for example, a stainless steel belt or a rotating metal drum, etc.).

The die can adjust the slit shape of a metal part, and pressurization die which is easy to adjust film thickness uniformly is preferable. Examples of the press die include a coat hanger die, a T-die and the like. It is preferable that the surface of a metal support body is mirror-processed.

3) Process of obtaining a web by evaporating the solvent from the flexible dope

The dope film is heated on a metal support to evaporate the solvent to obtain a web.

It is preferable to perform drying of a dope film in 40-100 degreeC atmosphere. In order to dry a dope film in 40-100 degreeC atmosphere, it is preferable to match 40-100 degreeC warm air to a web upper surface, or to heat in infrared rays.

As a method of evaporating the solvent, there is a method of blowing air on the surface of the dope film, a method of heating with liquid from the back of the belt, and a method of transferring from the front and back by radiant heat, but the drying efficiency of the belt is high. The method of heat-transferring with liquid from the back surface is preferable.

It is preferable to peel a web from a metal support body within 30 to 120 second after casting | flow_spread from a viewpoint of improving surface quality, moisture permeability, peelability, etc. of the web obtained.

4) peeling the web from the metal support

The obtained web is peeled off at the peeling position on the metal support. The temperature in the peeling position on a metal support body becomes like this. Preferably it is 10-40 degreeC, More preferably, it is 11-30 degreeC.

Although the amount of residual solvent of the web at the time of peeling at the peeling position on a metal support body changes also with drying conditions, the length of a metal support body, etc., it is preferable to set it as 50-120 mass%. A web with a large amount of residual solvent is too soft to easily damage flatness, and wrinkles and streaks in the casting direction (MD direction) due to peeling tension are likely to occur. The amount of residual solvent of the web at the peeling position can be set so that wrinkles or streaks in such a casting direction (MD direction) can be suppressed.

The residual solvent amount of the web is defined by the following formula.

Residual solvent amount (%) = (mass before heat treatment of web-mass after heat treatment of web) / (mass after heat treatment of web) × 100

The heat treatment at the time of measuring the amount of residual solvent means heat treatment at 115 占 폚 for 1 hour.

The peeling tension at the time of peeling a web from a metal support body can be 300 N / m or less normally.

5) The process of drying and extending a web and obtaining a film

The web obtained by peeling from a metal support body is dried. The web may be dried while being conveyed by a plurality of rolls arranged above and below, or may be dried while being conveyed by fixing both ends of the web with a clip.

The drying method of a web should just be a method of drying by hot air, an infrared ray, a heating roll, a microwave, etc., and the method of drying by hot air is preferable at the point which is simple. The drying temperature of a web can be about 40-250 degreeC, Preferably it is about 40-160 degreeC.

By stretching of the web, an optical film having a desired retardation is obtained. The retardation of an optical film can be controlled by adjusting the magnitude | size of the tension applied to a web.

Stretching of a web is extending | stretching of the width direction (TD direction), the casting direction (MD direction), or the diagonal direction of dope, It is preferable to extend | stretch at least in the width direction (TD direction). The stretching of the web may be uniaxial stretching or biaxial stretching. Biaxial stretching, Preferably, it is extending | stretching to the casting | flow_spread direction (MD direction) and the width direction (TD direction) of dope. Biaxial stretching may be sequential biaxial stretching, and may be simultaneous biaxial stretching.

Sequential biaxial stretching includes a method of sequentially performing different stretching directions, a method of dividing stretching in the same direction in multiple stages, and the like. Examples of sequential biaxial stretching include the following stretching steps.

Stretching in the casting direction (MD direction) Drawing in the stretching-width direction (TD direction) Drawing in the stretching-flexion direction (MD direction) Drawing in the stretching-flexion direction (MD direction)

Stretching in the width direction (TD direction)-Stretching in the width direction (TD direction)-Stretching in the flexible direction (MD direction)-Stretching in the flexible direction (MD direction)

Simultaneous biaxial stretching also includes a form in which stretching in one direction is performed and the tension in the other direction is relaxed to shrink.

Although the draw ratio also varies depending on the thickness of the optical film obtained and the retardation value to be obtained, finally, the stretching ratio is 0.8 to 1.5 times, preferably 0.8 to 1.1 times, in the casting direction; It may be 1.1 to 2.0 times in the width direction, preferably 1.3 to 1.7 times.

The drawing temperature of a web becomes like this. Preferably it is 120 degreeC-200 degreeC, More preferably, it is 150 degreeC-200 degreeC, More preferably, it can be more than 150 degreeC and 190 degrees C or less.

The stretching method of the web is not particularly limited, and a method of applying a circumferential speed difference to a plurality of rolls and stretching in a flexible direction (MD direction) using a roll circumferential speed difference therebetween (roll stretching method), both ends of the web Fixed with a clip or pin, and the gap between the clip and the pin is extended in the flexible direction (MD direction) by extending toward the flexible direction (MD direction), or extended in the width direction (TD direction) by stretching in the width direction (TD direction); And the method of extending in both the casting direction (MD direction) and the width direction (TD direction) and stretching in both the casting direction (MD direction) and the width direction (TD direction). These stretching methods may be combined.

Residual solvent of a web at the start of extending | stretching becomes like this. Preferably it is 20 mass% or less, More preferably, it can be 15 mass% or less.

In order to reduce the amount of solvent remaining in the film, the film obtained after stretching is further dried. It is preferable that it is 110-190 degreeC, and, as for a drying temperature, it is more preferable that it is 120-170 degreeC. If the drying temperature is too low, it is difficult to sufficiently evaporate the solvent. The drying method of a film can be a method of hitting a hot air, etc., conveying a film, for example.

6) Process of embossing in width direction both ends of film

Embossing is performed to the width direction both ends of the film obtained after extending | stretching. FIG. 5: is a schematic diagram which shows an example of the embossing processing apparatus 20. As shown in FIG. As shown in FIG. 5, the embossing apparatus includes an embossing roll 22 and a back roll 24 disposed to face the embossing roll 22 via the optical film 14.

It is preferable that it is 30-60 cm, and, as for the roll diameter of the embossing roll 22, it is more preferable that it is 30-50 cm. If the roll diameter of the embossing roll is more than 60 cm, since the distance between the heat source (disposed inside the embossing roll) and the surface of the embossing roll is too far, temperature unevenness may occur on the surface of the embossing roll. Therefore, a part with high elastic modulus and a low part generate | occur | produce in the embossing part formed, and the part with low elastic modulus is easy to be destroyed. On the other hand, when the roll diameter of the embossing roll is less than 30 cm, the rotating shaft is easy to shake; The height of the convex part of the embossing formed changes easily. The embossed portion formed higher than the set height tends to be broken.

The material of the back roll is preferably made of metal for reasons such as to uniformly cool the film on which the embossed portion is formed. The kind of metal may be SUS etc., for example. Since the metal back roll is easier to cool a film uniformly than a rubber back roll, for example, it is easy to crystallize cellulose acetate uniformly and can form the embossing part which has high strength (high elastic modulus).

The clearance between the embossing roll 22 and the back roll 24 is about 1 micrometer-30 micrometers, Preferably it can be about 1-15 micrometers. The nip pressure by the embossing roll 22 and the back roll 24 can be about 100-10000 Pa.

And the width direction both ends of the optical film 14 are nipped with the embossing roll 22 and the back roll 24, and embossing is performed to the width direction both ends of a film.

It is preferable to set it as 250-350 degreeC, and, as for the surface temperature of the embossing roll 22, it is more preferable to set it as 260-300 degreeC. When the surface temperature of the embossing roll 22 is less than 250 degreeC, since a film cannot fully melt | dissolve, it is difficult to fully crystallize a cellulose acetate even if it cools, and it is difficult to form a high embossing part. On the other hand, when the surface temperature of an embossing roll is more than 350 degreeC, a film melt | dissolves too much and the melt of a film tends to adhere to an embossing roll.

Although the surface temperature of the back roll 24 changes also with the surface temperature of the embossing roll 22, it is preferable to set it as 50-100 degreeC, and it is more preferable to set it as 50-80 degreeC. When the surface temperature of a back roll is less than 50 degreeC, since a film cools too rapidly, it is difficult to crystallize cellulose acetate uniformly, and the embossing part with high elastic modulus is hard to be obtained. On the other hand, when the surface temperature of a back roll exceeds 100 degreeC, since it is difficult to cool the cellulose acetate contained in a film, it is not only difficult to crystallize, but also a film thermally expands, and the front and back surface of the film near an embossing part tends to wave. When the wave front and back of the film of the embossing part generate | occur | produces, it will become easy for a film to stick together and a film will be torn easily.

It is preferable that it is 80-120 m / min, and, as for the conveyance speed of a film at the time of embossing, it is more preferable that it is 90-120 m / min. If the conveyance speed of a film is less than 80 m / min, productivity will fall easily. On the other hand, if the conveyance speed of a film exceeds 120 m / min, the pressure of an embossing roll and the heat of an embossing roll or a back roll will hardly be transmitted to a film uniformly. Therefore, it is difficult to crystallize the cellulose acetate contained in a film uniformly, and the embossed part with high strength is hard to be obtained.

That is, in order to form the embossed part which is hard to be destroyed, it is thought that it is important to 1) melt | dissolve cellulose acetate fully with an embossing roll, and to 2) slowly cool and crystallize the cellulose acetate melted with a back roll. For this purpose, it is preferable to adjust by various combinations of at least two or more of 1) the surface temperature of the embossing roll, 2) the surface temperature of the back roll, 3) the roll diameter of the embossing roll, and 4) the material of the back roll. Especially, it is preferable to adjust the surface temperature of 1) the embossing roll and the surface temperature of 2) the back roll in the above-mentioned range, respectively; 3) it is more preferable to adjust the embossing roll diameter to the above-mentioned range; 4) It is particularly preferable to select the material of the back roll.

7) Process of winding up film

The obtained elongate optical film is wound up in the longitudinal direction (vertical direction with respect to the width direction) of a film using a winding machine.

The winding method is not particularly limited and may be a positive torque method, a positive tension method, a tapered tension method, or the like.

The winding tension at the time of winding an optical film can be about 50-170N.

3. Polarizer

The polarizing plate of this invention is arrange | positioned at the polarizer and at least one surface, and includes the optical film obtained by the roll body of the optical film of this invention. The optical film obtained by the roll body of the optical film of this invention is an optical film obtained by the slit removing an embossing part. An optical film may be arrange | positioned directly on a polarizer, and may be arrange | positioned through another film or layer.

A polarizer is an element which passes only the light of a polarization plane of a predetermined direction. Representative examples of the polarizers are polyvinyl alcohol-based polarizing films, and there are ones in which iodine is dyed in a polyvinyl alcohol-based film and a dye in dichroic dye.

The polarizer may be a film obtained by uniaxially stretching a polyvinyl alcohol-based film and then dyeing with iodine or a dichroic dye, or uniaxially stretching the film after dyeing the polyvinyl alcohol-based film with iodine or a dichroic dye (preferably More preferably, a film subjected to durability treatment with a boron compound). It is preferable that it is 5-30 micrometers, and, as for the thickness of a polarizer, it is more preferable that it is 10-20 micrometers.

The polyvinyl alcohol-based film may be formed by forming a polyvinyl alcohol aqueous solution. An ethylene-modified polyvinyl alcohol film is preferable from the fact that a polyvinyl alcohol-type film is excellent in polarization performance and durability, and there is little color unevenness. Examples of ethylene-modified polyvinyl alcohol films include content of 1 to 4 mol%, polymerization degree 2000 to 4000, and saponification degree 99.0 to JP-A-2003-248123, JP-A-2003-342322, and the like. 99.99 mol% of film is included.

Examples of the dichroic dyes include azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes and anthraquinone dyes.

When the above-mentioned optical film is arrange | positioned at one surface of a polarizer, transparent protective films other than the above-mentioned optical film may be arrange | positioned at the other surface of a polarizer. Examples of the transparent protective film include commercially available cellulose ester films (for example, Konica Minolta Tak KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-HAW, KC8UY-HAW, KC8UY-HA, -RHA-C, KC8UXW-RHA-NC, KC4UXW-RHA-NC, and above Konica Minolta Opto Corporation are preferably used.

Although the thickness in particular of a transparent protective film is not restrict | limited, It can be about 10-200 micrometers, Preferably it is 10-100 micrometers, More preferably, it is 10-70 micrometers.

The polarizing plate of this invention can be manufactured through the step of removing the embossing part of the optical film in the roll body of this invention, and the step of bonding the optical film and polarizer in which the embossing part was removed.

As an adhesive agent used for joining, a fully saponified polyvinyl alcohol aqueous solution etc. are used preferably, for example.

4. liquid crystal display

The liquid crystal display device of this invention has a liquid crystal cell and a pair of polarizing plate which clamps it. And at least one of a pair of polarizing plate contains the optical film obtained from the roll body of the optical film of this invention.

It is a schematic diagram which shows the basic structure of one Embodiment of the liquid crystal display device which concerns on this invention. As shown in FIG. 6, the liquid crystal display device 30 includes a liquid crystal cell 40, a first polarizing plate 50 and a second polarizing plate 60 sandwiching the liquid crystal cell 40, and a backlight 70.

The display method of the liquid crystal cell 40 is not particularly limited, and may include a twisted nematic (TN) method, a super twisted nematic (STN) method, an in-plane switching (IPS) method, an optically compensated birefringence (OCB) method, or vertical alignment (VA). ) (MVA; Multi-domain Vertical Alignment or PVA; Patterned Vertical Alignment), and HAN (Hybrid Aligned Nematic). In order to raise contrast, VA (MVA, PVA) system is preferable.

The VA liquid crystal cell has a pair of transparent substrates and a liquid crystal layer sandwiched therebetween.

Among the pair of transparent substrates, a pixel electrode for applying a voltage to the liquid crystal molecules is disposed on one transparent substrate. The counter electrode may be disposed on the one transparent substrate (where the pixel electrode is disposed), or may be disposed on the other transparent substrate, and in order to increase the aperture ratio, the counter electrode is preferably disposed on the one transparent substrate (where the pixel electrode is disposed). .

The liquid crystal layer contains liquid crystal molecules having negative or positive dielectric anisotropy. When the liquid crystal molecules are not subjected to voltage (when no electric field is generated between the pixel electrode and the counter electrode) by the alignment regulating force of the alignment film provided on the surface on the liquid crystal layer side of the transparent substrate, the long axis of the liquid crystal molecules is formed on the surface of the transparent substrate. It is oriented so as to be substantially perpendicular to the angle.

In the liquid crystal cell configured as described above, 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 oriented perpendicularly to the surface of the transparent substrate are aligned so that their major axis is in the horizontal direction with respect 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 subpixel.

The 1st polarizing plate 50 is arrange | positioned at the visual recognition side, and has the 1st polarizer 52 and the protective films 54 (F1) and 56 (F2) which clamp it. The 2nd polarizing plate 60 is arrange | positioned at the backlight 70 side, and has the 2nd polarizer 62 and the protective films 64 (F3) and 66 (F4) which clamp it. One of the protective films 56 (F2) and 64 (F3) may be omitted as needed.

At least one of the protective films 54 (F1) and 66 (F4) among the protective films 54 (F1), 56 (F2), 64 (F3), and 66 (F4); Preferably, the protective film 66 (F4) is made into the optical film obtained from the roll body of the optical film of this invention.

[Example]

EMBODIMENT OF THE INVENTION Below, this invention is demonstrated in detail with reference to an Example. By these Examples, the scope of the present invention is not limited and interpreted.

1. Preparation of film materials

1) Cellulose Acetate

Cellulose acetate 1: acetyl group substitution degree (total substitution degree of acyl group) 2.9, weight average molecular weight Mw = 152000, number average molecular weight Mn = 90000, Mw / Mn = 1.7, SP value = 15.7

Cellulose acetate 2: acetyl group substitution degree (total substitution degree of acyl group) 2.45, weight average molecular weight Mw = 151000, number average molecular weight Mn = 100000, Mw / Mn = 1.5

2) plasticizer

TPP: triphenyl phosphate (SP value 10.7)

BDP: biphenyl diphenyl phosphate (SP value 11.0)

EPEG: ethyl phthalyl ethyl glycolate (SP value 10.9)

TMP-tribenzoate: trimethylolpropane tribenzoate (SP value 11.0)

Polyester compound A (mixture of n = 0 to 5, Mw 400, SP value 10)

Polyester compound B (m = 0-5, mixture of n = 0-5, Mw 400, SP value 10.1)

Polyester compound C (m = 1, n = 1, Mw = 1000, SP value = 10)

Polyester Compound D

SP value of the compound was computed based on the calculation method as described in the reference literature (p54-57 of the basic science of coating, Harada Yuji Makaki Shoten (1977)).

2. Manufacture of optical film

(Example 1)

Preparation of Inline Additives

After mixing 10 parts by mass of aerosil 972 V (manufactured by Nippon Aerosil Co., Ltd., average particle diameter of 16 nm, apparent specific gravity of 90 g / l) and 90 parts by mass of methanol with a dissolver for 30 minutes, Manton-Gaulin ) To obtain a fine particle dispersion.

88 mass parts of dichloromethane were thrown into the obtained fine particle dispersion, stirring, and it stirred and mixed for 30 minutes with the dissolver, and diluted. The obtained solution was filtered with the polypropylene wind cartridge filter TCW-PPS-1N by Adventic Toyo Co., to obtain a fine particle dispersion dilution liquid.

15 mass parts of tinuvin 928 (manufactured by BASF Japan Co., Ltd.) and 100 mass parts of dichloromethane were added to a sealed container, heated and stirred to completely dissolve, and then filtered. After adding 36 mass parts of said fine particle dispersion dilution liquids to the obtained solution, stirring for 30 more minutes, 6 mass parts cellulose ester 1 (acetyl group substitution degree 2.9, Mn = 90000, Mw = 152000, Mw / Mn = 1.7) was added. It was added with stirring, and further stirred for 60 minutes. The obtained solution was filtrated with Nippon Seisen Co., Ltd. FineMet NF, and the inline addition liquid was obtained. The filter medium used was 20 micrometers of nominal filtration accuracy.

Preparation of Main Doping Liquid

The following components were placed in a closed container and completely dissolved while heating and stirring. Azumi Rossi No. by Azumi Rossi Co., Ltd. Filtration at 24 afforded the main dope solution.

(Composition of the main doping solution)

Cellulose acetate 1 (acetyl group substitution degree 2.9 (total substitution degree of acyl group 2.9), Mn = 90000, Mw = 152000, Mw / Mn = 1.7): 100 parts by mass

Triphenyl phosphate (TPP, SP value 10.7): 5 parts by mass

Biphenyl diphenyl phosphate (BDP, SP value 11.0): 5 parts by mass

Dichloromethane (SP value 9.7): 430 parts by mass

Methanol (SP value 14.5): 40 parts by mass

100 mass parts of main dope liquid and 2.5 mass parts of in-line addition liquid were fully mixed with the in-line mixer (Toray static type internal tube mixer Hi-Mixer, SWJ), and the dope liquid was obtained.

The obtained dope liquid was cast on the stainless steel band support body on the stainless steel band support body uniformly on condition of 35 degreeC of dope liquid temperature, and 1.8 m in width. On the stainless steel band support body, the solvent in the obtained dope film was evaporated until residual solvent volume became 100%, and the web was obtained, and the web was peeled off from the stainless steel band support body. The obtained web was further dried at 35 ° C. and then slitted to a width of 1.65 m. Thereafter, the web was dried at a drying temperature of 160 ° C. while stretching the web 1.5 times in the TD direction (width direction of the film) in the tenter. The residual solvent amount of the web at the start of stretching was 20%. In addition, the draw ratio of MD direction computed from the rotational speed of a stainless steel band support body, and the operation speed of a tenter was 1.0 time. Then, after drying the obtained film for 15 minutes at 125 degreeC, conveying the inside of a drying apparatus with many rolls, it slitted in 2.2 m width, 10 micrometers in height of a convex part, and width w of a convex part is 100 micrometers in the width direction both ends. And an embossing portion (width W of the embossing portion: 15 mm) having a spacing of 1000 µm between the convex portions was formed. Embossing was performed on condition of the following.

(Embossing processing condition)

Embossing roll:

Material: stainless steel

Roll diameter: 30cm

Surface temperature: 270 ℃

Back roll:

Material: Metal (Stainless Steel)

Temperature: 60 ° C

Conveying speed of film: 90m / min

Conveying tension: 120N / m

Clearance of Embossing Roll and Back Roll: 27㎛

Nip Pressure with Embossing Roll and Back Roll: 150Pa

Thus, the long optical film of 2.2 m in width, 4000 m in length, and 30 micrometers in thickness which were obtained was wound up in the longitudinal direction, and the roll body of an optical film was obtained.

(Examples 2 to 22)

The optical film was prepared in the same manner as in Example 1 except that any one or more of the dope composition, the drying temperature of the film after stretching, the embossing processing condition, the winding length, and the thickness of the optical film were changed as shown in Table 1 or 3 below. A roll body was obtained. When the additive contained in dope is 1 type, content of an additive shall be 5 mass parts; In the case of two types, content of each additive was 5 mass parts, respectively.

(Comparative Examples 1 to 3)

The roll body of the optical film was obtained like Example 1 except having changed the drying temperature of the film after extending | stretching as shown in Table 2 below.

(Comparative Examples 4 to 5)

The roll body of the optical film was obtained like Example 1 except having changed the kind of solvent contained in dope as shown in Table 2. Among these, in Comparative Example 4, 40 parts by mass of methanol in Example 1 was changed to 40 parts by mass of ethanol; In the comparative example 5, it changed to butanol / methanol = 20 mass parts / 20 mass parts (40 mass parts in total).

(Comparative Examples 6 to 12)

The roll body of the optical film was obtained like Example 1 except having changed the embossing process conditions as shown in Table 2.

(Comparative Example 13)

The roll body of the optical film was obtained like Example 11 except having changed the casting thickness of dope so that the thickness of an optical film might be a value shown in following Table 4.

Table 1 shows the conditions for producing the roll body of the optical films of Examples 1 to 22; Table 2 shows the conditions for producing the roll body of the optical films of Comparative Examples 1 to 13.

The quantity of the solvent which remains in the obtained optical film, the fracture resistance of embossing, and the tearability of a film were evaluated with the following method.

(Amount of solvent remaining)

1) Construction of calibration curve

Samples of known methanol concentration were placed in dedicated vials, sealed with septum and aluminum caps, and set in a headspace sampler. The vial bottle was heated under the following headspace heating conditions to generate a volatile component, and the volatile component was measured by gas chromatography. Similar measurements were made for different samples of methanol concentration. And the peak area of the solvent in the GC chart obtained by each measurement was computed, the plot of the solvent concentration and peak area was produced, and the calibration curve was obtained. In the same manner, calibration curves for ethanol and butanol were also prepared.

(Headspace sampler)

Instrument: Hewlett-Packard, Inc. headspace sampler HP7694

Headspace heating conditions: 20 minutes at 120 ° C

(Gas chromatography)

A device: Hewlett-Packard Corporation type 5971

Column: J & W Corporation DB-624

Detector: Hydrogen Ionization Detector (FID)

GC temperature raising conditions: After holding for 3 minutes at 45 degreeC, it heated up to 100 degreeC at 8 degreeC / min.

GC introduction temperature: 150 ℃

2) Measurement of Solvent Residue in Optical Film

The film chopped to 10 cm in width and width was cut into fine particles of about 5 mm and sealed in a dedicated vial bottle in the same manner as in 1) above, followed by heat treatment under headspace heating conditions, and the resulting volatile components were measured by gas chromatography.

The peak area of each solvent was computed from the obtained chart, and it compared with the calibration curve obtained by said 1), and calculated | required the quantity of each solvent which remains in the film. The quantity of the solvent remaining in the film was calculated | required as mass ratio (mass%) with respect to the whole film.

(Destruction rate of embossing)

The part to which the embossed part of the obtained optical film was given was cut out, and 10 sample films of 5 cm in width and width were prepared. The sample film was placed on the stage of the thickness meter (Nikon Digital Micro MH-15M), and the height D ₀ of the embossed portion of the sample film was measured. Subsequently, as shown in Fig. 4, a cylindrical rod 18A made of metal having a diameter of 5 mm and mounted on the embossed portion 16 of the sample film 14A with respect to the film surface and the weights disposed thereon ( A total weight of 1 kg consisting of 18B) was placed. Thus, it was left to stand for 10 minutes at 23 degreeC 55% RH in the state which applied 1 kg of load to the circular area | region of 5 mm diameter on the surface of the embossing part 16 of a film. Then, the height D of the embossed part of the sample film 14A obtained by removing the weight 18 consisting of the cylindrical rod 18A and the weight 18B was measured in the same manner as described above. The obtained fracture rate was applied to the following formula 1 to calculate the fracture resistance.

&Quot; (1) &quot;

Fracture Resistance (%) = D / D ₀ × 100

The same measurement was performed also about the other 9 sample films, and the fracture resistance was computed. And the average value of the breakdown-proof rate obtained by ten measurements was calculated | required.

(Ease of rupture)

The roll body of the obtained optical film was preserve | saved for 24 hours under 23 degreeC 55% RH. Then, the optical film was unwound with a roll body, the width direction center part of the optical film of the winding core vicinity was cut out, and the sample film of width 50mm x length 64mm was obtained. After humidifying the obtained sample film at 23 degreeC 55% RH for 24 hours, Elmendorf tear strength based on ISO6383 / 2-1983 was measured.

Elmendorf tear strength was measured using a Toyo Seiki Co., Ltd. F9 elapsed vehicle bet tear tester. The tear strength was performed at 23 ° C. and 55% RH in the case of tearing in the longitudinal direction (MD direction) of the film and in the case of tearing in the width direction (TD direction) of the film, and the average value was defined as “tear strength”. .

Ease of rupture was evaluated based on the following criteria.

◎: tear strength is 50 mN or more

○: tear strength is 40 mN or more but less than 50 mN

○ △: tear strength is 30 mN or more but less than 40 mN

△: tear strength is more than 20 mN and less than 30 mN

X: tear strength is 10 mN or more but less than 20 mN

××: tear strength is less than 10 mN

Table 3 shows the evaluation results of the optical films obtained in Examples 1 to 22; Table 4 shows the evaluation results of the optical films obtained in Comparative Examples 1 to 13.

As shown in Tables 3 and 4, the optical films of Examples 1 to 22 in which the breakdown resistance of the convex portion of the embossed portion is 30% or more, and the amount of methanol remaining in the optical film of the roll body is in the range of 10 to 100 mass ppm. It turns out that a film is less likely to be torn than the optical film of Comparative Examples 1-13.

From the comparison of Comparative Examples 1 to 5, it can be seen that the optical film is likely to be torn even if the amount of methanol remaining in the film is too small or too large. That is, in the optical films of Comparative Examples 2 and 3 in which the amount of methanol remaining is too large, the plasticizer tends to move in the film, and it is considered that a portion where the additive is coarse and a dense portion are formed in the optical film. In addition, although the optical film of the comparative example 1 which has too little methanol residual is suppressed in the film | membrane of a plasticizer, since a solvent does not exist, since the flexibility of a film is impaired, it is thought that a film becomes easy to tear. .

From the contrast between Example 1 and Comparative Examples 6 and 7, if the surface temperature of the back roll is too low, it is difficult to crystallize the cellulose acetate uniformly, so that the embossed portion with high elastic modulus is not formed and the optical film is easily torn. Is suggested. Moreover, since a film thermally expands and the front and back surface of the film of the embossed part vicinity waved, it turns out that films adhere easily, and it is easy to tear an optical film. In contrast with Example 1 and Comparative Example 11, when a rubber back roll is used, it is more difficult to transfer heat to the film more uniformly than using a metal back roll. It cannot be crystallized and it suggests that the optical film obtained is easy to tear.

Industrial Applicability

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

10 rolls of optical film
12 winding cores
14 optical film
14A sample film
15 stages
16 Embossing Section
18A cylindrical rod
18B weight
18 weights
20 embossing processing equipment
22 embossing rolls
24 bag rolls
30 liquid crystal display
40 liquid crystal cells
50 first polarizer
52 First polarizer
54 Protective film (F1)
56 Protective film (F2)
60 second polarizer plate
62 Second polarizer
64 Protective film (F3)
66 Protective film (F4)
70 backlight
D, D ₀ Height of the convex portion of the embossed portion

Claims (8)

It is a roll body of the optical film obtained by winding up the optical film of 20-50 micrometers in thickness containing the cellulose acetate and the plasticizer whose SP values are 9-11 in a perpendicular direction with respect to the width direction of a film,
The optical film has an embossed portion at both ends in the width direction,
The height of the convex part of the said embossed part after storing for 10 minutes at 23 degreeC 55% RH on the surface of the said embossed part of the said optical film in the state which applied a 1 kg load to a 5 mm diameter circular area | region is called D, and before applying the said load. When the height of the convex portion of the embossed portion is D ₀ , the fracture resistance represented by the following Equation 1 is 30% or more,
&Quot; (1) &quot;
Fracture Resistance (%) = D / D ₀ × 100
The roll body of the optical film whose residual amount of methanol in the said optical film is 10-100 mass ppm with respect to the said optical film, and is more than any residual amount of ethanol and butanol in the said optical film. The roll body of the optical film of Claim 1 whose total substitution degree of the acetyl group of the said cellulose acetate is 2.3 or more and 2.95 or less. The roll body of the optical film of Claim 1 whose winding length of the said optical film is 1000 m or more and 8000 m or less. The roll body of the optical film of Claim 1 whose said plasticizer is triphenyl phosphate, ethyl phthalyl ethyl glycolate, or a polyester compound. The roll body of the optical film of Claim 1 whose content of the said plasticizer is 1-20 mass% with respect to the said cellulose acetate. The said polyester compound further capped the molecular terminal of the compound obtained by making the C1-C4 diol react with the dicarboxylic acid containing at least aromatic dicarboxylic acid further by aromatic group or aliphatic group. The roll body of the optical film. Removing the said embossed part of the said optical film in the roll body of the optical film of Claim 1,
Bonding the optical film and the polarizer having the embossed portion removed;
The manufacturing method of the polarizing plate which has. delete

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