KR20170062389A - Optical film and method of manufacturing the same, polarizing plate and liquid crystal display device - Google Patents

Abstract

An object of the present invention is to provide an optical film having good durability and suppressing a decrease in contrast of a liquid crystal display device, a manufacturing method thereof, a polarizing plate and a liquid crystal display device. The optical film of the present invention comprises a cycloolefin resin, at least one of an ultraviolet absorber and an antioxidant, and has a modified region containing a harmonized surface, wherein at the cut surface perpendicular to the surface of the optical film, The total content of the ultraviolet absorber and the antioxidant in the region S from the surface to the position of 0.1 t in the thickness direction is Ms and the total content of the ultraviolet absorber and the antioxidant in the region C from the center of the optical film to the position of +/- 0.1 t in the thickness direction Ms is not less than 0.01 and not more than 1, and the amount of the residual solvent contained in the optical film is not less than 100 ppm and not more than 2000 ppm And an internal haze: external haze = 1: 15 to 1: 1000.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical film, a polarizing plate, and a liquid crystal display device,

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

BACKGROUND ART Liquid crystal display devices are widely used as liquid crystal displays for televisions, notebook computers, and smart phones. A liquid crystal display device usually includes a liquid crystal cell and a pair of polarizing plates for supporting the liquid crystal cell; The polarizing plate includes a polarizer and a protective film.

As materials constituting the protective film, cellulose ester, polycarbonate and cycloolefin-based resins are known. Among them, a cycloolefin-based resin is preferably used from the viewpoint of having high heat resistance and moisture resistance.

On the other hand, when a film containing a cycloolefin-based resin as a main component is stretched, a weak layer is liable to be formed in the vicinity of the surface of the film. There is a problem that sufficient adhesion with a polarizer can not be obtained even if a polarizing plate is obtained by bonding a film having the weak layer to the polarizer via an aqueous adhesive agent because the weak layer has low impact resistance and tear strength . Therefore, it is proposed to increase the cohesive force of the surface by applying a solvent for applying an organic solvent to the surface of a stretched film containing a cycloolefin resin as a main component so that sufficient adhesion with a polarizer can be obtained even when an aqueous adhesive is used (See, for example, Patent Document 1).

Further, since the liquid crystal display device for mobile use is used outdoors, it is desired that the protective film has good durability (ultraviolet ray resistance and oxidation resistance). As such a protective film, there has been proposed an optical laminate comprising a cycloolefin resin and an ultraviolet absorber (for example, Patent Documents 2 and 3).

Japanese Patent No. 5712892 Japanese Patent Application Laid-Open No. 2015-031753 Japanese Patent Application Laid-Open No. 2015-045845

However, in the optical laminate of Patent Documents 2 and 3, an ultraviolet absorbent is contained only in the intermediate layer in order to suppress the bleeding-out of the ultraviolet absorbent at the time of melt film formation in that the optical laminate is produced by the melt film formation method. As described above, since the optical laminate of Patent Documents 2 and 3 has a multilayer structure, it is not only difficult to reduce the thickness, but also has a problem that it is liable to cause delamination.

On the other hand, a single-layer film can be obtained by producing a film containing a cycloolefin-based resin and an ultraviolet absorber by a cast film-forming method. However, the liquid crystal display device provided with the polarizing plate obtained by applying the solvent treatment described in Patent Document 1 to the surface of the single-layer film and bonding the polarizing film to the polarizer has a low contrast in some cases.

There has been a problem in that the liquid crystal display device provided with the polarizing plate obtained by applying the solvent treatment described in Patent Document 1 to the surface of the optical laminate of Patent Document 2 or 3 and bonding the polarizing plate to the polarizer has remarkable deterioration of contrast.

An object of the present invention is to provide an optical film having good durability and capable of suppressing a decrease in contrast of a liquid crystal display device.

[1] An optical film having a modified region including a roughened surface, wherein the optical film contains at least one of a cycloolefin resin, an ultraviolet absorber and an antioxidant, The total content of the ultraviolet absorber and the antioxidant in the region S from the harmonic surface to the position 0.1 t in the thickness direction is Ms and the sum of the thicknesses of the Ms is not less than 0.01 and not more than 1 when the total content of the ultraviolet absorber and the antioxidant in the region C up to the position of 0.1 t is Mc (the thickness of the optical film is t) Wherein an amount of the residual solvent contained in the optical film is 100 ppm or more and 2000 ppm or less, and an inner haze: an outer haze ratio is 1:15 to 1: 1000.

[2] The optical film according to [1], wherein the external haze is 0.1 to 5%.

[3] The optical film according to [1] or [2], wherein the content of the ultraviolet absorber is 0.5 to 5 mass% with respect to the cycloolefin resin.

[4] The optical film according to any one of [1] to [3], wherein the residual solvent comprises 100 to 300 ppm of toluene.

[5] The optical film according to any one of [1] to [4], wherein the Mc / Ms is 0.7 or less.

[6] A polarizing plate comprising an optical film according to any one of [1] to [5], and a polarizer disposed on a surface on which the modified region is formed.

[7] A liquid crystal display comprising a first polarizing plate, a liquid crystal cell, a second polarizing plate, and a backlight in this order, wherein the first polarizing plate comprises a first polarizer and a liquid crystal cell of the first polarizer And a protective film F2 disposed on the side of the liquid crystal cell side of the first polarizer, wherein the second polarizer comprises a second polarizer, and a protective film F2 disposed on the liquid crystal cell side of the second polarizer And a protective film F4 disposed on a surface of the second polarizer facing away from the liquid crystal cell, wherein at least one of the protective films F1 and F2 is formed by the steps [1] to [5 , And / or at least one of the protective films F3 and F4 is one of the films [1] to [4], wherein the first polarizer is disposed on a surface of the optical film, 5], and further, And the second polarizer is disposed on the surface on which the modified region of the optical film is formed.

[8] The optical film according to any one of [1] to [5], wherein at least one of the protective films F1 and F2 is disposed on a surface of the optical film on which the modified region is formed , And the liquid crystal display device described in [7].

[9] A film comprising at least one of a cycloolefin resin, an ultraviolet absorber and an antioxidant, and is characterized in that in the region S from the at least one surface to the position 0.1 t in the thickness direction , The total content of the ultraviolet absorber and the antioxidant in the region C from the center of the film to the position of ± 0.1 t in the thickness direction is represented by Mc (Wherein the thickness of the film is referred to as t), a cycloolefin-based resin film having a Mc / Ms of 0.01 or more and less than 1 and a residual solvent amount of 100 ppm or more and 2000 ppm or less, And a step of treating the surface constituting the region (S) with a solvent in contact with an organic solvent.

[10] The step of obtaining the cycloolefin resin film includes a step of dissolving at least one of the cycloolefin resin, the ultraviolet absorber and the antioxidant in a solvent containing 70% by mass or more of a good solvent to obtain a dope; , A step of softening the dope on a support and then drying until the amount of the residual solvent becomes 1 to 10% by mass to peel off the resulting flexible film to obtain a film; and a step of drying the film to obtain a cycloolefin resin film [9] The method for producing an optical film according to [9],

[11] The process for producing an optical film according to [10], wherein in the step of drying the film-like material to obtain a cycloolefin-based resin film, the film-like material is dried at 90 to 160 ° C.

According to the present invention, it is possible to provide an optical film having good durability and capable of suppressing a decrease in contrast of a liquid crystal display device.

1 is a schematic diagram showing an example of the configuration of the optical film of the present invention.
2 is a view for explaining the area S and the area C on the cut surface perpendicular to the surface of the optical film.
3 is a schematic diagram showing another example of the constitution of the optical film of the present invention.
4 is a view for explaining a measurement method of haze.
5 is a schematic diagram showing an example of a basic configuration of a liquid crystal display device.

As described above, films obtained by solvent-treating an optical laminate including a cycloolefin-based resin and an ultraviolet absorber and films obtained by solvent-treating a cast film containing a cycloolefin-based resin and an ultraviolet absorber as disclosed in Patent Documents 2 and 3 , The external haze tends to increase, and adhesion to the polarizer may not be obtained. Thereby, the contrast of the liquid crystal display device may be lowered.

On the other hand, the inventors of the present invention found that the optical film of the present invention, which is obtained by subjecting a cycloolefin-based resin film having a "residual solvent amount of a certain amount" to "a UV absorber or an antioxidant is localized on the surface" And the external haze is hardly increased excessively.

The reason for this is not clear, but it is presumed as follows. That is, since the ultraviolet absorber or the antioxidant is localized on the surface of the cycloolefin resin film, the ultraviolet absorber or antioxidant distributed on the surface when the solvent is treated can suppress excessive penetration of the solvent into the film . Similarly, since the cycloolefin-based resin film contains a certain amount or more of the residual solvent, the concentration gradient of the solvent on the surface and inside of the film can be made gentle when the solvent is treated, so that excessive penetration of the solvent into the film is suppressed .

As described above, excessive penetration of the solvent into the inside of the film by the solvent treatment can be suppressed, so that chemical cracks on the surface of the film can be suppressed, and the adhesion between the obtained optical film and the polarizer is hardly impaired. In addition, since the surface of the film is difficult to be excessively harmonized, it is possible to prevent the external haze of the obtained optical film from excessively increasing. As described above, since the adhesion to the polarizer is good and the excessive increase in external haze can be suppressed, deterioration of the contrast of the liquid crystal display device can be suppressed. The present invention has been made based on this finding.

1. Optical film

1 is a diagram showing an example of the configuration of the optical film of the present invention. As shown in Fig. 1, the optical film 10 of the present invention has a modified region 10A including a surface harmonized by a solvent treatment. The optical film (10) of the present invention contains at least one of a cycloolefin resin, an ultraviolet absorber and an antioxidant, and at least one of the ultraviolet absorber and the antioxidant is contained in the solvent treatment of the optical film (Refer to Fig. 1).

1-1. Cycloolefin resin

The cycloolefin-based resin is a polymer of a cycloolefin monomer, or a copolymer of a cycloolefin monomer and other copolymerizable monomers.

The cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton and more preferably a cycloolefin monomer having a structure represented by the following formula (A-1) or (A-2).

R ¹ to R ⁴ in the formula (A-1) independently represent a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group. Provided that R ¹ and R ² are not both hydrogen atoms, or R ³ and R ⁴ are hydrogen atoms at the same time, except when all of R ¹ to R ⁴ are hydrogen atoms.

The hydrocarbon group having 1 to 30 carbon atoms is preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrocarbon group having 1 to 5 carbon atoms. The hydrocarbon group having 1 to 30 carbon atoms may further have a linking group containing a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. Examples of such linking groups include divalent polar groups such as carbonyl group, imino group, ether bond, silyl ether bond, thioether bond and the like. Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group and the like.

Examples of the polar group include a carboxy group, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an allyloxycarbonyl group, an amino group, an amide group and a cyano group. Among them, a carboxy group, a hydroxy group, an alkoxycarbonyl group and an allyloxycarbonyl group are preferable, and an alkoxycarbonyl group and an allyloxycarbonyl group are preferable from the viewpoint of securing solubility at the time of solution casting.

P in the formula (A-1) represents an integer of 0 to 2. p is preferably 1 or 2.

R ⁵ in the formula (A-2) represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms. Among them, a hydrocarbon group of 1 to 5 carbon atoms is preferable, and a hydrocarbon group of 1 to 3 carbon atoms is more preferable.

R ⁶ in the formula (A-2) represents a polar group selected from the group consisting of a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, an allyloxycarbonyl group, an amino group, an amide group and a cyano group, or a halogen atom (fluorine, chlorine, Or an iodine atom). Among them, a carboxy group, a hydroxy group, an alkoxycarbonyl group and an allyloxycarbonyl group are preferable, and an alkoxycarbonyl group and an allyloxycarbonyl group are more preferable from the viewpoint of ensuring the solubility in forming the solution.

P in the formula (A-2) represents an integer of 0 to 2. p is preferably 1 or 2.

The cycloolefin monomers constituting the cycloolefin-based resin may be one type or two or more types. The cycloolefin monomer preferably contains at least a cycloolefin monomer in which at least one of R ¹ to R ⁴ in the formula (A-1) is a polar group or a cycloolefin monomer in which R ^{6 in the} formula (A-2) is a polar group.

That is, the cycloolefin-based resin preferably contains a structural unit derived from a cycloolefin monomer having these polar groups. The content of the structural unit derived from the cycloolefin monomer having a polar group may be, for example, 50 mol% or more, preferably 60 mol% or more, relative to the total number of moles of the structural units derived from a monomer constituting the cycloolefin resin And may be 100 mol%.

The cycloolefin monomer represented by the formula (A-2) has an asymmetric structure. That is, since the substituents R ⁵ and R ⁶ of the cycloolefin monomer represented by the formula (A-2) are substituted with only one ring-constituting carbon atom on the symmetry axis of the molecule, the symmetry of the molecule is low. Such a cycloolefin monomer can promote the diffusion movement of the ultraviolet absorber and the antioxidant when the flexible dope is dried in a process for producing a cycloolefin resin film to be described later, I think it can be done.

Specific examples of the cycloolefin monomers represented by the formula (A-1) are shown in Exemplary Compounds 1 to 14, and specific examples of the cycloolefin monomers represented by the formula (A-2) are shown in Exemplary Compounds 15 to 34.

Examples of copolymerizable monomers copolymerizable with the cycloolefin monomers include copolymerizable monomers capable of ring-opening copolymerization with cycloolefin monomers, and copolymerizable monomers capable of addition copolymerization with cycloolefin monomers.

Examples of the ring-opening copolymerizable copolymerizable monomers include cycloolefin monomers having no norbornene skeleton such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, dicyclopentadiene, and the like.

Examples of the addition-copolymerizable copolymerizable monomer include an unsaturated double bond-containing compound, a vinyl cyclic hydrocarbon monomer, and (meth) acrylate. Examples of the unsaturated double bond-containing compound include olefin compounds having 2 to 12 (preferably 2 to 8) carbon atoms, and examples thereof include ethylene, propylene, and butene. Examples of the vinyl cyclic hydrocarbon monomer include vinyl cyclopentene-based monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. (Meth) acrylate include alkyl (meth) acrylates having 1 to 20 carbon atoms such as methyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and cyclohexyl do.

The cycloolefin-based resin is obtained by polymerizing or copolymerizing a cycloolefin monomer having a norbornene skeleton, preferably a cycloolefin monomer having a structure represented by the formula (A-1) or (A-2) And examples thereof include the following.

(1) A ring-opening polymer of a cycloolefin monomer

(2) a ring-opening copolymer of a cycloolefin monomer and a copolymerizable monomer capable of ring-opening copolymerization with the cycloolefin monomer

(3) a hydrogenated product of the ring-opened (co) polymer of the above (1) or (2)

(4) The ring-opened (co) polymer of the above (1) or (2) is cyclized by the Friedel-Crafts reaction,

(5) Saturated copolymers of a cycloolefin monomer and an unsaturated double bond-containing compound

(6) an addition copolymer of a cycloolefin-based monomer with a vinyl-based cyclic hydrocarbon monomer and a hydrogenated product thereof

(7) an alternating copolymer of a cycloolefin-based monomer and (meth) acrylate

Among them, (1) to (3) are preferable, and (3) is more preferable. That is, the cycloolefin-based resin is preferably a copolymer comprising a structural unit represented by the following formula (B-1) and a structural unit represented by the following formula (B-2) in view of increasing the glass transition temperature of the resulting cycloolefin- Or a structural unit represented by the following formula (1). The structural unit represented by the formula (B-1) is a structural unit derived from a cycloolefin monomer represented by the above-described formula (A-1) Is a structural unit derived from a cycloolefin monomer represented by the formula (A-2).

Of formula X (B-1) is, -CH = CH- or -CH ₂ CH ₂ - it is.

The general formula R ¹ to R ⁴ and p the (B-1) is a respective agreement with R ¹ to R ⁴ and p of the formula (A-1).

Of formula X (B-2) is, -CH = CH- or -CH ₂ CH ₂ - it is.

To the general formula R ⁵ R ⁶ and p in the (B-2) is a respective agreement and R ⁵ to R ⁶ and p of the formula (A-2).

The cycloolefin-based resin can be obtained by any known method, for example, the methods described in Japanese Patent Application Laid-Open Nos. 2008-107534, 2005-227606, and 4466272. For example, the polymer of (3) hydrogenates the double bond of the main chain of the resulting ring-opening polymer after solution polymerization of the monomer. The catalyst is removed from the polymer obtained after the hydrogenation (decatalysis), and further dried under reduced pressure to remove the solvent (desolvation) to obtain the polymer (3). The adjustment of the amount of the residual solvent in the resulting optical film can be carried out by adjusting the kind of the solvent used for the solution polymerization and the drying conditions for removing (removing solvent) the solvent from the obtained ring-opening polymer in the synthesis of the cycloolefin resin .

The intrinsic viscosity [?] Inh of the cycloolefin resin is preferably 0.2 to 5 cm 3 / g, more preferably 0.3 to 3 cm 3 / g, and still more preferably 0.4 to 1.5 cm 3 / g.

The number average molecular weight (Mn) of the cycloolefin-based resin is preferably 8000 to 100000, more preferably 10,000 to 80,000, and still more preferably 12,000 to 50,000. The weight average molecular weight (Mw) of the cycloolefin-based resin is preferably 20,000 to 300,000, more preferably 30,000 to 25,000, and still more preferably 40,000 to 200,000. The number average molecular weight and the weight average molecular weight of the cycloolefin resin can be measured in terms of polystyrene by gel permeation chromatography (GPC).

When the intrinsic viscosity [?] Inh, the number-average molecular weight and the weight-average molecular weight fall within the above range, the cycloolefin-based resin has good heat resistance, water resistance, chemical resistance, mechanical properties and molding processability as a film.

The glass transition temperature (Tg) of the cycloolefin-based resin is usually 110 占 폚 or higher, preferably 110 to 350 占 폚, more preferably 120 to 250 占 폚, and even more preferably 120 to 220 占 폚. If Tg is 110 deg. C or more, it is easy to suppress deformation under high temperature conditions. On the other hand, when the Tg is 350 DEG C or less, the molding process is facilitated and deterioration of the resin due to heat at the time of molding can be suppressed easily.

The content of the cycloolefin resin is preferably 70 mass% or more, more preferably 80 mass% or more, with respect to the optical film.

1-2. Ultraviolet absorber

The ultraviolet absorber is added for the purpose of improving the durability of the optical film. Such ultraviolet absorber is preferably a compound which absorbs ultraviolet rays of 400 nm or less, specifically, a compound having a transmittance of light having a wavelength of 370 nm of not more than 10%, preferably not more than 5%, more preferably not more than 2% to be.

Examples of the ultraviolet absorber include oxibenzophenone compounds, benzotriazole compounds, salicylic ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders, and polymer ultraviolet absorbers . The ultraviolet absorber may be a single type or a combination of two or more types.

Among them, a benzotriazole-based compound, a benzophenone-based compound and a triazine-based compound are preferable, and a benzotriazole-based compound and a benzophenone-based compound are more preferable because they have good ultraviolet absorption ability.

Examples of the benzotriazole-based compound include 5-chloro-2- (3,5-di-sec-butyl-2-hydoxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol- ) -6- (straight chain and branched dodecyl) -4-methylphenol. Examples of benzophenone-based compounds include 2-hydroxy-4-benzyloxybenzophenone and 2,4-benzyloxybenzophenone.

Examples of commercially available products include Tinuvin series such as Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328 and Tinuvin 928, all of which are commercially available from BASF.

The content of the ultraviolet absorber (total content in the optical film) is preferably 0.1 to 10% by mass, for example, with respect to the cycloolefin resin. When the content of the ultraviolet absorber is 0.1% by mass or more, the durability (in particular, weather resistance) of the optical film can be sufficiently increased. If the content of the ultraviolet absorber is 10 mass% or less, the transparency of the optical film is hardly impaired. The content of the ultraviolet absorber is more preferably 0.5 to 5% by mass.

1-3. Antioxidant (deterioration inhibitor)

The antioxidant may be added for the purpose of suppressing deterioration of the optical film under high temperature and high humidity. Examples of the antioxidant include hindered phenol-based compounds. Examples of hindered phenolic compounds include 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5- Propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol- Di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5- 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5- Hydroxybenzyl) -isocyanate, and the like. The antioxidant may be a single type or a combination of two or more types.

Among them, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t- butyl-4-hydroxyphenyl) propionate] Ethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferable.

Examples of the antioxidant include hydrazine-based metal inactivators such as N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris -Di-t-butylphenyl) phosphite, or the like.

The content of the antioxidant (total content in the optical film) is, for example, preferably 0.1 to 10% by mass based on the cycloolefin-based resin. When the content of the antioxidant is 0.1% by mass or more, the durability (particularly weather resistance) of the optical film can be sufficiently increased. If the content of the antioxidant is 10 mass% or less, the transparency of the optical film is hardly impaired. The content of the antioxidant is more preferably 0.5 to 5% by mass.

It is preferable that at least one of the ultraviolet absorber and the antioxidant is localized on the surface harmonized by the solvent treatment of the optical film (see Fig. 1). In the example of Fig. 1, the darker gradation region indicates a region where the ultraviolet absorber and the antioxidant are localized.

(Content distribution of ultraviolet absorber / antioxidant)

Specifically, the total content of the ultraviolet absorber and antioxidant in the region C (intermediate layer region) of the optical film on the cut surface perpendicular to the surface of the optical film is denoted by Mc, and the total content of the ultraviolet ray When the total content of the absorbent and the antioxidant is Ms, it is preferable that Mc / Ms is 0.01 or more and less than 1, more preferably 0.01 or more and 0.7 or less. When Mc / Ms is less than 1, preferably 0.7 or less, the ultraviolet absorber or antioxidant is localized in the surface layer among optical films. Therefore, when the surface of the cycloolefin-based resin film is treated with a solvent to obtain an optical film, excessive penetration of the solvent into the inside of the film can be suppressed. As a result, it is possible to suppress excessive increase in the external haze of the obtained optical film surface, and also to suppress deterioration of the adhesiveness with the polarizer due to chemical cracks.

2 is a view for explaining the area S and the area C on the cut surface perpendicular to the surface of the optical film. In the drawing, the upper side is a harmonized side. As shown in FIG. 2, the region S represents a surface layer region from the harmonic surface of the optical film to a position of 0.1 t (t: thickness of the optical film) in the thickness direction, and the region C represents the surface region from the center of the optical film And an intermediate layer region of up to ± 0.1 t in the thickness direction.

The area S including at least the harmonized surface of the optical film 10 has only to satisfy Mc / Ms less than 1 (see Figs. 1 and 2). The surface layer region from the uncoated side of the optical film to the position of 0.1 t in the thickness direction (t: thickness of the optical film) is referred to as a region S ', and the ultraviolet absorber and antioxidant (Ms') is more than 0.01 and less than 1, preferably more than 0.01 and not more than 0.7 (see Figs. 3 and 2).

The distribution state and Mc / Ms of the ultraviolet absorber or antioxidant in the optical film can be measured by the following method. In other words,

1) The optical film 10 is cut with a microtome to obtain a cut surface perpendicular to the surface of the optical film 10.

2) The surface distribution image of the organic substance in the measurement area including the area S and the area C in the cut surface of the obtained optical film 10 was measured by the ATR method using Nicolet 380 manufactured by Thermo Fisher Scientific. The measurement area can be a 1.5 t 占 1.5 t area (including area S and area C) including the area S and the area C, when the thickness of the optical film is t.

3) A peak (measurement target peak) of the ultraviolet absorber or antioxidant to be measured is extracted, the content is quantified from the absorbance, and a visualized IR image is obtained. From the IR image, the state of distribution of the ultraviolet absorber or antioxidant on the cut surface of the optical film 10 is grasped.

The value of Mc / Ms can be obtained from the ratio of the integrated value of the absorbance of the measurement target peak in the region S and the integrated value of the absorbance of the measurement target peak in the region C in the measurement region. The measurement target peak is to be measured in advance. The value of Mc / Ms' can also be measured in the same manner.

The Mc / Ms can be adjusted by, for example, the solvent composition of the dope and the amount of residual solvent of the membrane before drying (wet state) in the production process of the optical film. In order to localize the ultraviolet absorber / antioxidant on the surface layer of the optical film, it is preferable that the amount of the residual solvent in the film before drying (wet state) is small. For example, And the amount of the residual solvent in the membrane before drying is preferably reduced. It is not clear why the Mc / Ms is easily adjusted to the above range (the ultraviolet absorber and the antioxidant tend to be distributed on the surface) if the amount of residual solvent in the membrane before drying is small. However, the production of a cycloolefin- It is considered that when the residual solvent amount of the membrane product before drying is low, the ultraviolet absorber and antioxidant near the surface of the membrane product are hardly volatilized and tend to be concentrated on the surface of the membrane product.

1-4. Other components

The optical film may further contain other additives insofar as the effect of the present invention is not impaired. Examples of other additives include plasticizers, heat stabilizers, fine particles (matting agents), surfactants, fluorine-based surfactants and release auxiliary agents.

(Fine particles)

The fine particles can be provided with irregularities on the surface of the optical film to improve the slidability. The fine particles may be inorganic fine particles or organic fine particles. Examples of the inorganic fine particles include fine particles of inorganic oxides such as silica, titania, alumina and zirconia; Fine particles of calcium carbonate, talc, clay, fired kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate and the like. Examples of the organic fine particles include fine particles such as silicone resin, fluororesin, and (meth) acrylic resin. Of these, silica particles are preferable because they are less likely to generate haze and less discolored.

The average particle diameter of the fine particles is preferably 1 nm to 500 nm, more preferably 5 nm to 300 nm. By setting the average particle diameter to 1 nm or more, the slidability of the adhesion-facilitating layer can be effectively increased, and when it is 500 nm or less, the haze can be suppressed to be low. The average particle diameter of the fine particles is a particle diameter distribution (50% volume cumulative diameter D50) in which the cumulative volume calculated on the small diameter side is 50% in the measured particle diameter distribution by measuring the particle diameter distribution by the laser diffraction method.

The content of the fine particles may be 10% by mass or less with respect to the optical film.

1-5. Structure and properties of optical film

The optical film of the present invention has the modified region 10A formed by the solvent treatment as described above (see Fig. 1). The thickness of the modified region 10A is preferably 10 to 1000 nm, more preferably 20 to 800 nm.

Whether or not the modified region 10A exists can be confirmed by the following procedure. That is, the optical film is cut with a microtome, and a sample having a cut surface perpendicular to the surface of the optical film is obtained. The cut surface of the obtained sample is observed with a transmission electron microscope (TEM), and the modified region 10A is identified from the difference in contrast (dark and light) of the obtained TEM image.

The modified region 10A may be formed on both sides of the optical film 10, or may be formed on only one side.

In the optical film 10 including the modified region 10A, the external haze is suitably high. That is, the ratio of the internal haze to the external haze of the optical film is preferably 1: 15 to 1: 1000. When the inner haze: external haze = 1: 15 or more, the solvent is appropriately penetrated and roughened, so that good adhesion with the polarizer is easily obtained. When the internal haze: external haze = 1: 1000 or less, the surface is not roughened excessively, so that the excessive increase in haze can be suppressed and the adhesiveness with the polarizer is also hardly impaired. The ratio of the internal haze and the external haze is preferably 1: 20 to 1: 500, more preferably 1: 30 to 1: 200.

The external haze of the optical film is preferably 0.1 to 10%. When the external haze is 10% or less, deterioration of the contrast of the liquid crystal display device can be satisfactorily suppressed. The external haze of the optical film is more preferably 0.1 to 5%.

The value of the ratio of the internal haze of the optical film to the external haze or the external haze can be adjusted by the content of the ultraviolet absorber or the antioxidant, Mc / Ms, or the residual solvent amount of the optical film. In order to prevent the external haze of the optical film from becoming excessively high (relative to the internal haze), it is preferable to suppress excessive penetration of the solvent into the inside of the film in the solvent treatment in obtaining the optical film. In order to suppress the excessive penetration of the solvent by the solvent treatment, the content of the ultraviolet absorber or the like is preferably set to a predetermined value or more, Mc / Ms is preferably set to a certain value or less, .

The internal haze and the external haze of the optical film can be measured by the following procedure.

1) Measurement of overall haze

The optical film is humidified for 5 hours or more in an environment of 23 ° C and 55% RH. Thereafter, the total haze of the resulting optical film was measured with a haze meter (Model NDH 2000, manufactured by Nippon Denshoku Co., Ltd.).

2) Measurement of internal haze

i) First, blank haze 1 without optical film is measured. That is, a drop (0.05 ml) of glycerin was dropped onto the cleaned slide glass, and the laminate obtained by raising the cover glass was set in a haze meter (type NDH 2000, manufactured by Nippon Denshoku Co., Ltd.), and blank haze 1 was measured do.

ii) Next, the haze 2 including the optical film is measured. That is, glycerin (0.05 ml) was dropped onto the cleaned slide glass (see Fig. 4 (a)), and the humidity-controlled optical film was placed thereon without bubbles (see Fig. 4 (b)). Then, glycerin (0.05 ml) was dropped onto the optical film (see Fig. 4 (c)), and a cover glass was placed thereon (see Fig. 4 (d)). The obtained laminate is set in the above-mentioned haze meter, and haze 2 is measured.

iii) The internal haze of the optical film is calculated by substituting the values measured in i) and ii) into the following equation.

Internal haze of optical film = (haze 2) - (haze 1)

In the measurement of haze, glass and glycerin are the same as those used in Examples described later.

3) Measurement of external haze

The value of the total haze obtained in the above 1) and the value of the internal haze obtained in the above 2) are substituted into the following equations to calculate the external haze.

External haze (%) of optical film = total haze - internal haze

(Residual solvent amount)

The amount of the residual solvent contained in the optical film is preferably 100 to 2000 ppm. In the present invention, ppm represents ppm by mass. Such an optical film is obtained by subjecting a cycloolefin-based resin film having a residual solvent amount of 100 to 2000 ppm to a solvent treatment. When the amount of the residual solvent contained in the cycloolefin based resin film is 100 ppm or more, the concentration gradient of the solvent on the surface and inside of the film can be reduced when the solvent is treated, so that excessive penetration of the solvent into the film is suppressed, It is possible to suppress the increase of the external haze and the deterioration of the adhesion. If the amount of the residual solvent contained in the cycloolefin-based resin film is 2000 ppm or less, the strength of the optical film is hardly damaged. The amount of the residual solvent contained in the optical film is more preferably 100 to 800 ppm.

The amount of the residual solvent contained in the optical film includes an organic solvent remaining in the modified region by the solvent treatment, but the amount thereof is very small as compared with the amount of residual solvent contained in the optical film (cycloolefin-based resin film) before the solvent treatment . Therefore, the amount of the residual solvent contained in the optical film is substantially the same as the amount of the residual solvent contained in the optical film (cycloolefin-based resin film) before the solvent treatment.

The optical film preferably contains 100 to 300 ppm of toluene as a residual solvent. Toluene is excellent in compatibility with cycloolefin resins, and prevents excessive penetration of the solvent into the film when the film containing it is subjected to solvent treatment, and suppresses excessive increase of chemical cracks and external haze It is because.

The qualitative and quantitative determination of the residual solvent contained in the optical film can be performed by headspace gas chromatography. That is, in the headspace gas chromatography, the sample is sealed in a container and heated, and the gas in the container is quickly injected into the gas chromatograph in the state that the container is filled with the volatile component, and mass analysis is performed to identify the compound, Is carried out. The volatile component can be quantitatively determined by previously preparing a calibration curve using a sample having a known concentration and comparing the peak area of the volatile component obtained by the measurement with the calibration curve. The specific measuring apparatus and measurement conditions are the same as those in the following embodiments.

The amount of the residual solvent contained in the optical film is determined by the drying conditions at the time of desolvation at the time of synthesis of the cycloolefin resin as described above; (Drying conditions in the process of (1-3) described later) of the film in producing the optical film. In order to keep the amount of the residual solvent contained in the optical film at a certain level or more, the drying temperature at the time of desolvation in the synthesis of the cycloolefin resin is lowered; The drying temperature in the step (1-3) described later in the production of the optical film may be lowered.

The optical film preferably has an in-plane slow axis. The optical film having the in-plane slow axis is obtained by stretching a cycloolefin based resin film. That is, the direction of the in-plane slow axis can be parallel to the maximum stretching direction. On the surface of the optical film obtained by stretching the cycloolefin-based resin film, a fragile layer is liable to be formed. Since the fragile layer is vulnerable to impact and is liable to peel off, the optical film having the fragile layer is difficult to obtain adhesiveness with the polarizer. In order to increase the impact resistance and tear strength of the optical film having such a weak layer, a solvent treatment is required. In an optical film requiring such a solvent treatment, it is particularly effective to set Mc / Ms to less than 1 and to set the residual solvent amount to a certain level or more.

The in-plane slow axis refers to an axis having the maximum refractive index within the plane of the film. The in-plane slow axis of the optical film can be confirmed by an automatic birefringence index liquid scanning (Axo Scan Mueller Matrix Polarimeter: manufactured by Liquid Matrix Co., Ltd.).

(Phase difference value)

The optical film can take various retardation values depending on its application. For example, when the optical film is used as an optical film of a VA mode or IPS mode liquid crystal display device, the in-plane retardation Ro measured in an environment of a measurement wavelength of 590 nm and 23 占 폚 55% RH of the optical film and The retardation Rth in the thickness direction may satisfy the following relationship, for example.

0 nm? Ro? 300 nm

-200 nm? Rth? 200 nm

The retardation Ro in the in-plane direction of the optical film preferably satisfies 50? Ro? 250nm, more preferably 50nm? Ro? 200nm. It is more preferable that the retardation Rth in the thickness direction of the optical film satisfies -150 nm? Rth? 150 nm, more preferably -120 nm? Rth? 120 nm.

The Ro and Rth of the optical film are respectively defined by the following formulas.

(2a): Ro = (nx-ny) xd

(2b): Rth = ((nx + ny) / 2-nz) xd

(Wherein,

nx represents the refractive index in the in-plane slow axis direction of the optical film,

ny represents a refractive index in a direction orthogonal to the in-plane slow axis of the optical film,

nz represents the refractive index in the thickness direction of the optical film,

and d represents the thickness (nm) of the optical film)

The measurement of Ro and Rth of the optical film can be performed by the following method.

1) The optical film is humidity-conditioned at 23 ° C and 55% RH for 24 hours. The average refractive index of this optical film is measured by an Abbe refractometer, and the thickness d is measured by using a commercially available micrometer.

2) The retardation Ro and Rth of the optical film after humidity control at a measurement wavelength of 590 nm were measured at 23 ° C and 55% RH using an automatic birefringence meter (Axo Scan Mueller Matrix Polarimeter) Lt; / RTI > Specifically,

i) Ro is measured by using a liquid scans when light having a measurement wavelength of 590 nm is incident parallel to the normal direction of the film surface.

ii) When a light having a measurement wavelength of 590 nm is incident on an inclined axis (rotation axis) of the sample surface in the in-plane slow axis from the angle (incident angle [theta]) with respect to the normal to the surface of the sample piece by liquid scanning, The phase difference R ([theta]) was measured. The measurement of the phase difference R ([theta]) is performed at 6 points per 10 [deg.] In the range of 0 [deg.] To 50 [deg.]. The in-plane ground axis of the sample piece is confirmed by the liquid scan.

iii) Based on the measured Ro and R (?), the liquid crystal scan calculates nx, ny and nz from the above-described average refractive index and thickness, and calculates Rth at a measurement wavelength of 590 nm based on the formula (2b) .

(thickness)

The thickness of the optical film varies depending on the required range of Ro and Rth, but is preferably 10 to 200 占 퐉, preferably 10 to 100 占 퐉, more preferably 15 to 60 占 퐉, Is more preferable.

2. Manufacturing method of optical film

The optical film of the present invention is a film comprising 1) a cycloolefin resin, at least one of an ultraviolet absorber and an antioxidant, satisfies Mc / Ms of 0.01 to less than 1, and satisfies a residual solvent amount of 100 ppm to 2000 ppm To obtain a cycloolefin-based resin film, and 2) a step of bringing the surface constituting the region S of the cycloolefin-based resin film into contact with an organic solvent and then performing a solvent treatment.

2-1. 1)

A cycloolefin resin film comprising a cycloolefin resin and at least one of an ultraviolet absorber and an antioxidant, wherein Mc / Ms is 0.01 or more and less than 1, and a residual solvent amount is 100 ppm or more and 2000 ppm or less is obtained. The Mc / Ms of the cycloolefin-based resin film is defined similarly to Mc / Ms in the optical film. That is, Mc of the cycloolefin-based resin film represents the total content of the ultraviolet absorber and the antioxidant in the region C (intermediate layer region) of the cycloolefin-based resin film; The Ms in the cycloolefin-based resin film represents the total content of the ultraviolet absorber and the antioxidant in the region S including the side on which the solvent treatment of the cycloolefin-based resin film is carried out.

Specifically, (1-1) a step of dissolving at least one of the above-mentioned cycloolefin resin, ultraviolet absorber and antioxidant in a solvent to obtain a dope; (1-2) A step of softening the dope on a support and then peeling to obtain a membrane-like product, and (1-3) a step of drying the membrane. Between (1-2) and (1-3), it is preferable to further perform the step of (1-4) stretching the film.

(1-1)

At least one of the cycloolefin resin, ultraviolet absorber and antioxidant is dissolved in a solvent to obtain a dope. At least one of the cycloolefin resin, the ultraviolet absorber and the antioxidant may be mixed and dissolved in a solvent at the same time to obtain a dope. Alternatively, at least one of the resin solution in which the cycloolefin resin is dissolved in a solvent and at least one of the ultraviolet absorber and the antioxidant may be dissolved in a solvent May be mixed to obtain a dope.

The solvent used in the dope is selected such that Mc / Ms in the optical film is within the above-mentioned range. The solvent used in the dope preferably contains one or more kinds of good solvents for the cycloolefin-based resin.

Examples of a good solvent for the cycloolefin resin include alicyclic hydrocarbons such as cyclohexane, methylcyclohexane and ethylcyclohexane; Aromatic hydrocarbons such as toluene and xylene; Halogenated hydrocarbons such as dichloromethane and chloroform; Aliphatic ethers such as diethyl ether, tetrahydrofuran and cyclopentyl methyl ether; And aliphatic hydrocarbons such as pentane, hexane and heptane. Of these, methylene chloride is preferable in view of easy dissolution of the cycloolefin-based resin.

The solvent used for the preparation of the dope may further contain a poor solvent of cycloolefin resin as required. Examples of the poor solvent include linear or branched aliphatic alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-butanol, and tetrahydrofuran.

When a good solvent and a poor solvent are used in combination, it is preferable to increase the content ratio of the good solvent (low boiling point solvent) in order to adjust Mc / Ms to the above-mentioned range. This is because it is easy to adjust the residual solvent amount of the membrane before drying to a certain value or less by increasing the content ratio of the good solvent (low boiling point solvent), depending on the conditions (time or temperature) at the time of removing the solvent. Concretely, the content ratio of the good solvent is 51 to 100 mass% (preferably 70 to 99 mass%, more preferably 80 to 99 mass%) and the content ratio of the poor solvent is 0 to 49 mass% Preferably 1 to 30% by mass, and more preferably 1 to 20% by mass).

The resin concentration of the dope is preferably as high as possible from the viewpoint of reducing the drying load after being softened on the metal support, but the load during filtration is increased and the filtration accuracy is deteriorated. The resin concentration of the dope that is compatible with them is preferably 10 to 35 mass%, more preferably 15 to 25 mass%.

The dissolution of the resin can be carried out in a usual manner. When heating and pressurization are combined, heating can be performed at a boiling point or more at normal pressure. It is preferable to dissolve the solvent under stirring at a temperature higher than the boiling point of the solvent at normal pressure and at a temperature at which the solvent does not boil under pressure to prevent the formation of massive unheated products. Further, after the resin is mixed with a poor solvent and wetted or swollen, a good solvent may be added and dissolved.

The pressurization can be performed by a method of pressurizing an inert gas such as nitrogen gas or a method of expressing the vapor pressure of the solvent by heating. The heating is preferably performed from the outside, and for example, a jacket type is preferable because temperature control is easy.

The heating temperature at the time of dissolving the resin is preferably as high as possible from the viewpoint of the solubility of the resin, but if the heating temperature is too high, the pressure required becomes large and the productivity is deteriorated. The heating temperature is preferably 45 to 120 ° C, more preferably 60 to 110 ° C, and even more preferably 70 to 105 ° C.

It is preferable to filter the obtained dope with a filter material in view of suppressing foreign matter failure. The filtered dope is defoamed, and then supplied to the flexible die by a feed pump.

(1-2)

The obtained dope is discharged from a flexible die to be plied on a metal support, and the obtained flexible film is dried and peeled to obtain a film-like product.

The metal support may be a stainless steel belt or a casting finish drum. The surface of the metal support is preferably mirror-finished.

The surface temperature of the metal support is preferably from -50 deg. C to less than the boiling point of the solvent because the higher the drying speed of the film-like product is, the higher the film-forming property is. Therefore, the surface temperature of the metal support is preferably 0 to 40 캜, more preferably 5 to 30 캜.

The amount of the residual solvent (amount of residual solvent before drying) at the time of peeling from the metal support is preferably from 1 to 10 mass%, more preferably from 5 to 10 mass%, and more preferably from 5 to 10 mass%, in order to set the Mc / Ms of the cycloolefin- By mass to 9% by mass.

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

Amount of residual solvent (mass%) = {(M-N) / N} 100

(M represents the mass of the membrane, and N represents the mass after the membrane is heated at 120 DEG C for 1 hour)

The film-like material obtained by peeling may be further dried if necessary.

(1-4)

It is preferable to adjust the retardation by stretching the film-like material obtained by peeling.

The stretching can be performed in at least one direction. The stretching direction may be either the longitudinal direction (MD direction) of the membrane-like material, the width direction (TD direction) orthogonal to the longitudinal direction of the membrane-like material, and the oblique direction with respect to the longitudinal direction of the membrane-like material. The stretching may be successive stretching or simultaneous stretching.

For example, when the optical film functions as a? / 4 film to be described later, it is preferable to stretch in an oblique direction. The stretching in the oblique direction can be set so that the in-plane slow axis in the obtained optical film is 20 to 70 deg., Preferably 30 to 60 deg., More preferably 40 to 50 deg., Relative to the longitudinal direction of the film. When the optical film functions as a VA retardation film, it is preferable to stretch in the film width direction (TD direction).

The stretching magnification depends on the required optical performance, but may be 1.03 to 2.00 times, for example, in order to obtain an optical film functioning as a? / 4 film or a VA retardation film. The stretching magnification is defined as (stretching direction size of the laminate after stretching) / (stretching direction size of the laminate before stretching).

When the glass transition temperature of the cycloolefin-based resin is Tg, the stretching temperature is preferably Tg-30 ° C to Tg + 60 ° C, more preferably Tg-10 ° C to Tg + 50 ° C.

The amount of the residual solvent in the film at the start of the stretching is preferably 20 to 100% by mass. The amount of the residual solvent in the film at the end of the stretching is 10 mass% or less, preferably 5 mass% or less.

The stretching in the MD direction can be performed by, for example, causing a plurality of rolls to have a peripheral speed difference and using a roll speed difference therebetween. The stretching in the TD direction can be performed, for example, by fixing both ends of the film-like material with clips or pins and extending the distance between the clips and the pin in the advancing direction. These may be combined. The stretching in the oblique direction is preferably performed by an oblique stretching device. As the oblique stretching device, it is possible to freely set the orientation angle (angle with respect to the longitudinal direction of the in-plane slow axis) of the obtained cycloolefin-based resin film by variously changing the rail pattern, It is preferable to be capable of aligning uniformly to the left and right with high accuracy.

(1-3)

The membrane obtained in (1-2) or (1-4) is dried to obtain a cycloolefin resin film. The amount of the residual solvent in the cycloolefin-based resin film can be adjusted mainly in this step. Therefore, the drying temperature and the drying time can be adjusted so that the amount of the residual solvent in the cycloolefin resin film to be obtained is in the above-mentioned range.

The drying temperature is preferably about 40 to 250 ° C, more preferably 40 to 160 ° C, and even more preferably 90 to 160 ° C. It is preferable that the rapid drying be performed at a high temperature so that the amount of the residual solvent in the film-like product is not more than 8% by mass since the planarity of the obtained cycloolefin-based resin film is easily impaired. The drying time can be adjusted according to the type of solvent used in the dope.

The film-like material can be dried by a roll drying method in which film-like materials are alternately passed through a plurality of rolls arranged in a drying apparatus and the film-like material is conveyed while being dried, or by a tenter drying method in which both ends of a film- .

The drying method is not particularly limited and may be performed by hot air, infrared rays, heating rolls, microwaves or the like, and is preferably performed by hot air in terms of simplicity.

2-2. 2)

The surface of the obtained cycloolefin-based resin film constituting the above-described region S is brought into contact with an organic solvent and subjected to a solvent treatment. Thereby, an optical film having a modified region including a surface harmonized by solvent treatment is obtained.

The organic solvent used in the solvent treatment preferably contains a good solvent for the cycloolefin resin and more preferably a mixture of a good solvent and a poor solvent for the cycloolefin resin.

Examples of the good solvent for the cycloolefin resin used in the solvent treatment include alicyclic hydrocarbons such as cyclohexane, methylcyclohexane and ethylcyclohexane; Aromatic hydrocarbons such as toluene and xylene; Halogenated hydrocarbons such as dichloromethane and chloroform; Aliphatic ethers such as diethyl ether, tetrahydrofuran and cyclopentyl methyl ether; And aliphatic hydrocarbons such as pentane, hexane and heptane. Of these, alicyclic hydrocarbons and aliphatic ethers are preferred from the viewpoint of easy solvent treatment.

Examples of the poor solvent of the cycloolefin resin used in the solvent treatment include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; Aliphatic alcohols such as isopropanol and butanol; And aliphatic esters such as ethyl acetate, propyl acetate, isopropyl acetate and butyl acetate. Among them, ketones are preferable in view of easy treatment with a suitable solvent.

The method of contacting the cycloolefin resin film with an organic solvent can be carried out by a method in which an organic solvent is added to the surface of the film by a method such as a flexographic method, a Meyer bar coating method, a gravure coating method, a comma coating method, a doctor blade method, a die coating method, And the like.

Then, the film side in contact with the organic solvent is dried. The drying may be natural drying or heat drying. From the viewpoint of preventing deformation of the optical film, it is preferable that the film is dried at a temperature lower than the glass transition point of the cycloolefin resin film. The drying may be performed simultaneously with the solvent treatment, or may be performed after the solvent treatment.

3) The step of hydrophilizing the surface of the cycloolefin-based resin film may be further performed between the step of 1) and the step of 2) or after the step of 2), if necessary.

2-3. 3)

Examples of the hydrophilizing treatment include corona discharge treatment, plasma treatment, frame treatment, etch treatment, glow treatment, ozone treatment, and primer coating treatment. Above all, from the viewpoint of productivity, corona treatment and plasma treatment are preferable.

The corona discharge treatment is a method of treating a surface of a cycloolefin resin film by applying a high frequency and a high voltage between a dielectric and an insulated electrode to generate a corona and allowing the cycloolefin resin film to pass between the dielectric and the electrode. As a result, the adhesiveness of the surface of the cycloolefin resin film is enhanced.

Examples of the electrode material include ceramics and aluminum. The distance between the electrode and the dielectric is preferably 1 to 5 mm, more preferably 1 to 3 mm. The line speed (moving speed) is preferably about 3 to 70 m / min, more preferably about 3 to 50 m / min.

The corona output intensity is preferably 0.2 kW to 3 kW, and more preferably 0.5 kW to 1.5 kW. If the corona output intensity is less than 0.2 kW, the corona discharge becomes unstable and it may be difficult to impart a stable adhesive force to the surface of the cycloolefin resin film. If the corona output strength is larger than 2.0 kW, the cycloolefin-based resin film may be easily scratched. The electron dose in the corona discharge treatment may be 100 to 1000 W / m < 2 > / min.

The plasma treatment is a treatment for activating the surface of the cycloolefin resin film by performing plasma discharge under a gas atmosphere such as an inert gas or an oxygen gas generated under a reduced pressure or an atmospheric pressure. Plasma treatment under atmospheric pressure is preferable for efficient production under transport using a roll.

The plasma treatment can variously modify the surface of the cycloolefin-based resin film by variously changing the kind of gas. Therefore, in activating the surface of the cycloolefin-based resin film, the kind of gas can be appropriately and arbitrarily selected. Examples of gas species has, include fluorine-containing compounds, such as nitrogen, oxygen, argon, helium, acrylic acid, hydroxy _{alkyl, CF 4, CHF 3 C 2} F 6.

The plasma output is preferably 0.2 kW to 3 kW. The line speed (moving speed) is preferably 3 to 70 m / min, more preferably 3 to 50 m / min. The frequency is preferably 3 to 30 kHz, more preferably 5 to 20 kHz.

In the present invention, the cycloolefin-based resin film obtained in the above-described process 1) has a surface (UV absorber or antioxidant) distributed on its surface (Mc / Ms is less than 1) and contains a certain amount or more of residual solvent. Thereby, in the step 2) described above, it is possible to suppress excessive penetration of the solvent into the film when the solvent treatment is performed. Thereby, excessive increase of the external haze of the obtained optical film can be suppressed, and also the adhesiveness between the optical film and the polarizer can be increased.

3. Polarizer

The polarizing plate of the present invention comprises a polarizer and two protective films, and at least one of the protective films can be an optical film of the present invention. When the optical film of the present invention is disposed on only one side of the polarizer, another optical film may be disposed on the other side of the polarizer.

3-1. Polarizer

A polarizer is a device that allows only light of a polarization plane in a certain direction to pass. A typical polarizer currently known is a polyvinyl alcohol polarizing film. The polyvinyl alcohol polarizing film includes a polyvinyl alcohol film stained with iodine and a dichroic dye stained.

The polyvinyl alcohol polarizing film may be a film obtained by uniaxially stretching a polyvinyl alcohol film and then dyed with iodine or a dichroic dye (preferably a film subjected to further durability treatment with a boron compound); The film may be a uniaxially stretched film (preferably a film obtained by further durability treatment with a boron compound) after dying a polyvinyl alcohol film with iodine or dichromatic dye. The absorption axis of the polarizer is usually parallel to the maximum stretching direction.

For example, an ethylene-modified (meth) acrylate having an ethylene unit content of 1 to 4 mol%, a degree of polymerization of 2000 to 4000 and a degree of saponification of 99.0 to 99.99 mol% as disclosed in Japanese Patent Application Laid-Open Nos. 2003-248123 and 2003-342322 Polyvinyl alcohol is used. Among them, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature of 66 to 73 占 폚 is preferably used.

The thickness of the polarizer is preferably 5 to 30 占 퐉, and more preferably 5 to 20 占 퐉 for reasons such as making the polarizing plate thinner.

3-2. The optical film of the present invention

The optical film of the present invention can be disposed on at least one side of the polarizer. The surface on which the modified region of the optical film of the present invention is formed and the polarizer may be laminated directly or via an adhesive layer.

When the optical film of the present invention is used as a? / 4 film, the angle between the in-plane slow axis of the optical film of the present invention and the absorption axis of the polarizer is preferably 20 to 70 °, more preferably 30 to 60 ° More preferably 40 to 50 DEG. When the optical film of the present invention is used as a VA retardation film, the in-plane slow axis of the optical film of the present invention and the absorption axis of the polarizer can be substantially orthogonal.

3-3. Other optical films

Other optical films may be arranged on the other side of the polarizer, if necessary. Examples of other optical films include commercially available cellulose acylate films (for example, Konica Minolta Tact KC6UA, KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR- 1, KC8UY-HA, KC8UX-RHA, KC8UE, KC4UE, KC4HR-1, KC4KR-1, KC4UA, KC6UA or more. Konica Minolta Opto Co., Ltd.).

The thickness of the other optical film is not particularly limited, but is preferably 10 to 100 占 퐉, more preferably 10 to 60 占 퐉, and particularly preferably 20 to 60 占 퐉.

3-4. Method for producing polarizer

The polarizing plate of the present invention can be obtained by bonding a polarizer and a surface on which the modified region of the optical film of the present invention is formed, with an adhesive or an adhesive.

The adhesive may be a water-based adhesive containing a polyvinyl alcohol resin or urethane resin as a main component, or a photo-curable adhesive containing a photo-curable resin such as an epoxy resin as a main component. The pressure-sensitive adhesive may include an acrylic polymer, a silicone-based polymer, a polyester, a polyurethane, a polyether, or the like as a base polymer. Of these, water-based adhesives are preferable because they have good affinity with the optical film of the present invention and are hard to be deformed by absorption.

The bonding of the polarizer and the optical film of the present invention can usually be performed by roll-to-roll.

In the optical film of the present invention, chemical cracks during solvent treatment are suppressed. Thereby, when the polarizer is bonded to the surface on which the modified region of the optical film is formed, good adhesion with the polarizer can be obtained.

4. Liquid crystal display

The liquid crystal display of the present invention includes a liquid crystal cell and a pair of polarizing plates for supporting the liquid crystal cell.

5 is a schematic diagram showing an example of a basic configuration of a liquid crystal display device. 5, the liquid crystal display 20 of the present invention includes a liquid crystal cell 30, a first polarizing plate 40 and a second polarizing plate 50 for supporting the liquid crystal cell 30, a backlight 60 .

The display mode of the liquid crystal cell 30 may be, for example, TN (Twisted Nematic), VA (Vistical Aligment), or IPS (In Plane Switching) mode. The liquid crystal cell for a mobile device is preferably, for example, an IPS mode. For liquid-crystal cells of medium and large-sized applications, for example, a VA mode is preferable.

The first polarizing plate 40 is disposed on the viewing side surface of the liquid crystal cell 30 and includes a first polarizer 41 and a protective film disposed on a surface opposite to the liquid crystal cell of the first polarizer 41 43 (F1) disposed on the liquid crystal cell side of the first polarizer 41, and a protective film 45 (F2) disposed on the surface of the first polarizer 41 on the liquid crystal cell side.

The second polarizing plate 50 is disposed on the backlight side of the liquid crystal cell 30 and includes a second polarizer 51 and a protective film 53 And a protective film 55 (F4) disposed on a surface of the second polarizer 51 opposite to the liquid crystal cell.

It is preferable that the absorption axis of the first polarizer 41 and the absorption axis of the second polarizer 51 are orthogonal.

The protective film 45 (F2) may be an optical film of the present invention. The surface on which the modified region 45A of the optical film is formed and the first polarizer 41 are laminated directly or via an adhesive layer (not shown). The in-plane slow axis of the protective film 45 (F2) and the absorption axis of the first polarizer 41 can be substantially orthogonal. The protective films 43 (F1), 53 (F3) and 55 (F4) may be made of, for example, the above-mentioned other optical films.

5, the protective films 45 (F2), 53 (F3), and 55 (F2) are not limited to the optical films of the present invention, (F4) may be used as the optical film of the present invention. For example, when the protective film 43 (F1) is used as the optical film of the present invention and functions as a? / 4 film, the in-plane slow axis of the optical film of the present invention and the absorption axis of the first polarizer 41 The angle formed may be 40 to 50 degrees, as described above. When the protective film 45 (F2) is used as the optical film of the present invention and functions as a VA retardation film, the in-plane slow axis of the optical film of the present invention and the absorption axis of the first polarizer 41 may be approximately orthogonal have.

The optical film of the present invention as the protective film 45 (F2) contains an ultraviolet absorber and an antioxidant and has improved adhesion to the polarizer. In the optical film of the present invention, the external haze is reduced to a certain level or less. Therefore, the liquid crystal display device using the optical film of the present invention has good durability and good contrast.

[Example]

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

1. Material of cycloolefin resin film

1) Cycloolefin resin

(Synthesis Example 1)

100 parts by mass of Exemplary Compound 11 represented by the formula (A-1), 3.6 parts by mass of 1-hexene as a molecular weight regulator, 200 parts by mass of toluene were charged in a nitrogen-purged reaction vessel as a cycloolefin monomer, . To this was added 0.17 parts by mass of a toluene solution of 1.5 mol / l of triethylaluminum ((C ₂ H ₅ ) ₃ Al) as a polymerization catalyst, and tungsten hexachloride (WCl ₆ ) modified with t-butanol and methanol , 1.0 part by mass of a WCl ₆ solution (concentration: 0.05 mol / l) having a molar ratio of t-butanol: methanol: tungsten = 0.35: 0.3: 1 was added and the mixture was heated and stirred at 80 ° C for 3 hours to effect a ring- . The polymerization conversion rate in this polymerization reaction was 96%.

4000 parts by mass of the obtained polymer solution was placed in an autoclave and 0.48 parts by mass of RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to this polymer solution. Under the conditions of a hydrogen gas pressure of 10 MPa and a reaction temperature of 160 ° C And the mixture was heated and stirred for 3 hours to carry out a hydrogenation reaction.

After the obtained reaction solution was cooled, the hydrogen gas was purged, and this reaction solution was poured into a large amount of methanol to separate and recover the coagulated product. The recovered coagulated material was dried to obtain a cycloolefin resin 1.

(Synthesis Examples 2 to 4)

Cycloolefin-based resins 2 to 4 were obtained in the same manner as in Synthesis Example 1, except that the hydrogenation reaction solution was subjected to separation by filtration and the reduced-pressure drying temperature was changed as shown in Table 1.

2) Ultraviolet absorber

Ultraviolet absorber A: Tinuvin 928 (2- (2H-benzotriazol-2-yl) -6- (1 -methyl- 1 -phenylethyl) -4- (1,1,3,3-tetramethylbutyl) (See the following formula)

UV absorber B: N, N ', N "-tri-m-toluyl-1,3,5-triazine-2,4,6-triamine

UV absorber C: CHIMASSORB 81 (see formula below)

3) Antioxidants

Antioxidant: IRGANOX 1010 (see formula below)

2. Preparation of cycloolefin-based resin film

<Production of cycloolefin-based resin film 1>

(Preparation of fine particle addition liquid)

The following components were mixed with a dissolver for 50 minutes with stirring, and then dispersed with mannitol. Further, the particles were dispersed in the attritor so that the particle diameter of the secondary particles became a predetermined value. This was filtered with Finetmet NF manufactured by Nippon Seisen Co., Ltd. to obtain a fine particle addition liquid.

Fine particles (Aerosil R812: manufactured by Nippon Aerosil Co., Ltd., primary average particle diameter: 7 nm, apparent specific gravity: 50 g / L): 4 parts by mass

Methylene chloride: 96 parts by mass

(Preparation of dope solution)

Subsequently, the following components were dissolved sufficiently while heating to obtain a dope solution.

1: 100 parts by mass of the cycloolefin-based resin obtained in Synthesis Example 1

UV absorber A: 8 parts by mass

IRGANOX1010 (antioxidant): 0.2 parts by mass

Methylene chloride: 210 parts by mass

Fine particle addition liquid: 3 parts by mass

(Production of cycloolefin-based resin film by solution casting method)

The obtained dope was kept at 40 캜 and uniformly plied on a stainless steel belt, which was an endless metal support kept at 40 캜. This flexible film was dried until the residual solvent amount became 80% by mass, and then peeled off from the stainless steel belt to obtain a film-like product. The obtained film was dried at 40 占 폚 until the amount of residual solvent became 5 mass%, and then stretched in the transverse direction at a draw ratio of 1.5. The resulting film was further dried at 120 캜 while being conveyed by a plurality of rolls to obtain a cycloolefin based resin film 1 having a thickness of 20 탆 and a width of 1.3 m.

<Production of cycloolefin-based resin films 2 to 5>

Cycloolefin-based resin films 2 to 5 were obtained in the same manner as in cycloolefin-based resin film 1 except that the solvent composition of the dope was changed as shown in Table 2.

<Production of cycloolefin-based resin films 6 to 11>

Cycloolefin-based resin films 6 to 11 were obtained in the same manner as in cycloolefin-based resin film 3 except that the solvent composition of the dope and the drying temperature after stretching were changed as shown in Table 2.

<Production of cycloolefin-based resin films 12 to 16>

Cycloolefin-based resin films 12 to 16 were obtained in the same manner as in the preparation of cycloolefin-based resin film 3 except that the content of the ultraviolet absorber contained in the dope was changed as shown in Table 2.

<Production of cycloolefin-based resin film 17>

A cycloolefin based resin film 17 was obtained in the same manner as the cycloolefin based resin film 6 except that the content of the ultraviolet absorber contained in the dope was changed as shown in Table 2.

<Production of cycloolefin-based resin films 18 to 20>

Cycloolefin-based resin films 18 to 20 were obtained in the same manner as in the production of cycloolefin-based resin film 15 except that the kinds of cycloolefin-based resins contained in the dope were changed as shown in Table 2. [

<Production of cycloolefin-based resin films 21 to 23>

Cycloolefin-based resin films 21 to 23 were obtained in the same manner as in the production of cycloolefin-based resin film 2, except that the kind and content of the ultraviolet absorber contained in the dope were changed as shown in Table 2. [

<Production of cycloolefin-based resin film 24>

(Production of pellets)

100 parts by mass of the cycloolefin resin 1 dried, 3 parts by mass of the ultraviolet absorber A and 0.2 parts by mass of IRGANOX 1010 (antioxidant) were mixed by a twin-screw extruder. The resulting mixture was poured into a hopper connected to an extruder, and melt extruded by a single-screw extruder to obtain pellets.

Subsequently, the pellets thus obtained were placed in a hopper equipped with a double-flight type 50 mm single-screw extruder (ratio L / D of screw effective length L to screw diameter D = 32) equipped with a leaf disk-shaped polymer filter having a mesh interval of 3 탆 , And the molten resin was supplied to the die at an extruder outlet temperature of 280 ° C and a gear pump rotational speed of 10 rpm. Then, the molten resin was discharged from the die at 280 占 폚 and cast into a cooling roll adjusted to a temperature of 150 占 폚 to obtain a cycloolefin-based resin film 24. The air gap size was 50 mm.

<Production of cycloolefin-based resin film 25>

A cycloolefin based resin film 25 was obtained in the same manner as in the production of the cycloolefin based resin film 21 except that the stretching was not performed and the kinds of poor solvents were changed to those shown in Table 2. [

<Production of cycloolefin-based resin film 26>

A cycloolefin based resin film 26 was obtained in the same manner as in the production of cycloolefin based resin film 2 except that the ultraviolet absorber was not added and the cycloolefin resin 1 was added in an amount of 108 parts by mass.

The content distribution (Mc / Ms) of the ultraviolet absorber and antioxidant and the residual solvent amount of the obtained cycloolefin resin film were measured by the following methods, respectively.

(Mc / Ms)

The Mc / Ms of the obtained cycloolefin-based resin film was measured by the following procedure. In other words,

1) The cycloolefin-based resin film was cut with a microtome to obtain a cut surface perpendicular to the surface of the cycloolefin-based resin film.

2) The surface distribution (IR image) of the measurement object on the cut surface of the obtained cycloolefin based resin film was measured by ATR method using Nicolet 380 manufactured by Thermo Fisher Scientific.

(Measuring conditions)

Measurement area: 30 mu m x 30 mu m (area including the surface and the inside of the cycloolefin-based resin film)

3) A peak (measurement target peak) of the ultraviolet absorber or antioxidant to be measured was extracted from the measurement region, and the content was quantified from the absorbance to obtain a visualized IR image.

Further, in the measurement region, an integrated value As1 of absorbance of a measurement target peak in a region from one surface of the cycloolefin-based resin film to a position of 2 m in the thickness direction, Of the absorption peak of the measurement target peak in the region from the center of the cycloolefin resin film in the thickness direction to the position of +/- 2 mu m in the thickness direction And the Ac / As1 and Ac / As2 were calculated, respectively. Among these ratios, the smaller value was defined as "Mc / Ms".

(Qualitative and quantitative determination of residual solvent)

Qualitative and quantitative determination of the residual solvent in the obtained cycloolefin-based resin film was carried out by headspace gas chromatography. In the headspace gas chromatography, a sample is sealed in a container and heated. Then, the gas in the container is rapidly injected into the gas chromatograph while the container is filled with the volatile components, and the mass is analyzed to identify the compound. . The volatile component was quantitatively determined by previously preparing a calibration curve using a sample having a known concentration and comparing the peak area of the volatile component obtained by the measurement with the calibration curve.

(Measuring conditions)

Headspace apparatus: HP7694 Head Space Sampler (manufactured by Hewlett-Packard Company)

Temperature condition: Transfer line 200 ℃, Loop temperature 200 ℃

Sample volume: 0.8 g / 20 ml vial

GC: HP5890 (manufactured by Hewlett-Packard Company)

MS: HP5971 (manufactured by Hewlett-Packard Company)

Column: HP-624 (30 m x 0.25 mm ID)

Oven temperature: initial temperature 40 占 폚 (holding time 3 minutes), heating rate 10 占 폚 / min, reached temperature 200 占 폚 (holding time 5 minutes)

Measurement mode: SIM (Select Ion Monitor) mode

Production conditions and evaluation results of the cycloolefin-based resin films 1 to 26 are shown in Table 2. In the table, MC represents methylene chloride, Et represents ethanol, and Me represents methanol.

It was confirmed that the cycloolefin based resin films other than the cycloolefin based resin films 4, 5 and 24 were all omnipresent to the ultraviolet absorber or antioxidant on either side or one side of the film from the IR image. As shown in Table 2, by adjusting the solvent composition of the dope in the production process of the cycloolefin resin film and the amount of the solvent remaining in the film before drying, the Mc / Ms of the cycloolefin resin film obtained is reduced to less than 1 (Comparison of cycloolefin-based resin films 1 to 5). Concretely, when the content of methylene chloride having a low boiling point is large, the amount of the residual solvent in the membrane before drying tends to decrease, and the Mc / Ms of the cycloolefin-based resin film tends to be lower than a certain level.

The amount of residual solvent in the cycloolefin resin film obtained can be made to be equal to or more than a certain level by lowering the drying temperature of the film in the production process of the cycloolefin based resin film (comparison of cycloolefin based resin films 6 to 11) .

The amount of residual toluene in the cycloolefin resin film obtained by lowering the synthesis conditions (reduced pressure drying temperature) of the cycloolefin-based resin can be set to a certain level or more (comparison with cycloolefin-based resin films 15 and 18 to 20).

3. Fabrication of optical film

1) Preparation of treatment liquid

<Preparation of Treatment Solution 1>

Cyclopentyl methyl ether (CPME) and acetone were mixed with cyclopentyl methyl ether (CPME): acetone = 3: 7 (volume ratio) to obtain treated liquid 1.

<Preparation of treatment liquid 2>

N-Butyl acetate and 2-propanol were mixed in n-butyl acetate: 2-propanol = 3: 7 (volume ratio) to obtain Treatment solution 2.

<Preparation of Treatment Solution 3>

Toluene and methyl ethyl ketone were mixed in toluene: methyl ethyl ketone = 1: 9 (volume ratio) to obtain Treatment solution 3.

&Lt; Preparation of treatment liquid 4 &

Toluene and methyl ethyl ketone were mixed in toluene: methyl ethyl ketone = 3: 7 (volume ratio) to obtain Treatment liquid 4.

2) Fabrication of optical film

&Lt; Production of optical films 1 to 26 >

Corona discharge treatment was performed on the surface constituting the area S of the cycloolefin resin film shown in Table 3 (surface having a value of Mc / Ms in Table 2) under the condition of an electron irradiation amount of 500 W / m 2 / min. On the corona-treated surface of the obtained film, the above-prepared treatment liquid 1 was coated with a bar coater, followed by drying at 30 DEG C for 2 minutes to perform solvent treatment. As a result, optical films 1 to 26 having a modified region with a thickness of 800 nm were obtained.

&Lt; Fabrication of optical films 27 to 29 >

Optical films 27 to 29 were obtained in the same manner as in the production of optical film 21 except that the treatment liquid used for solvent treatment was changed to the treatment liquid shown in Table 3. [

<Fabrication of optical film 30>

In the production of the optical film 21, an optical film 30 was obtained in the same manner except that the solvent treatment was not performed.

The adhesive property and haze (internal haze, external haze) of the resulting optical film to the polarizer were evaluated by the following methods.

(Adhesiveness to Polarizer)

1) Production of polarizer

A polyvinyl alcohol film having a thickness of 25 占 퐉 was swelled with water at 35 占 폚. The obtained film was immersed in an aqueous solution containing 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds and immersed in an aqueous solution at 45 캜 containing 3 g of potassium iodide, 7.5 g of boric acid and 100 g of water. The resulting film was uniaxially stretched under the conditions of a stretching temperature of 55 캜 and a draw ratio of 5. The uniaxially stretched film was washed with water and then dried to obtain a polarizer having a thickness of 7 탆.

2) Preparation of sample for evaluation

A 3% by mass aqueous solution of polyvinyl alcohol (PVA-117H manufactured by Kurara) as an aqueous adhesive was applied to the surface of the obtained optical film on which the modified region was formed, and then the prepared polarizer was bonded. The bonding was performed so that the slow axis of the optical film and the absorption axis of the polarizer were orthogonal. The resulting laminate was dried at 60 DEG C for 5 minutes to obtain an evaluation sample.

The obtained evaluation sample was allowed to stand for 24 hours in an environment of 23 ° C and a relative humidity of 55%. Thereafter, the occurrence of material breakage and the degree of peeling when the adhesive surface of the polarizing film and the optical film of the evaluation sample were peeled by hand were visually observed, and the adhesiveness was evaluated on the basis of the following criteria. If it is equal to or greater than?, It is determined that there is no problem in practical use.

◎: Not peeled off

?: There is no problem in the adhesive force between the optical film and the polarizer, and when the optical film is peeled off, material (substrate) destruction occurs in at least one of the end portions of the optical film and the polarizer

?: There is no problem with the adhesive force between the optical film and the polarizer, and when attempting to peel off the optical film, a hard material (substrate) breakage occurs in at least one of the end portions of the optical film and the polarizer

X: The interface between the optical film and the polarizer was peeled off.

(Hayes)

1) Measurement of overall haze

The optical film was humidity-conditioned for 5 hours or more in an environment of 23 占 폚 and 55% RH, and then the total haze of the obtained optical film was measured with a haze meter (Model NDH 2000, manufactured by Nippon Denshoku Co., Ltd.).

2) Measurement of internal haze

i) First, blank haze 1 containing no optical film was measured by the following procedure. That is, one drop of glycerin (0.05 ml) was dropped onto the cleaned slide glass. At this time, bubbles were prevented from entering the droplet. Then, the cover glass was placed on the dropped glycerin. Glycerin spread even though the cover glass was not pressed. The obtained laminate was set in a haze meter (type NDH 2000, manufactured by Nippon Denshoku Co., Ltd.), and blank haze 1 was measured.

ii) Next, the haze 2 including the optical film was measured by the following procedure.

Glycerin (0.05 ml) was added dropwise to the slide glass (see Fig. 4 (a)). Then, the humidity-controlled optical film was placed thereon so that air bubbles did not enter (see Fig. 4 (b)). Then, glycerin (0.05 ml) was dropped onto the optical film (see Fig. 4 (c)). Then, a cover glass was placed thereon (see Fig. 4 (d)). The above-prepared laminate (cover glass / glycerin / optical film / glycerin / slide glass) was set in the above-mentioned haze meter, and haze 2 was measured.

iii) The internal haze of the optical film was calculated by substituting the values measured in i) and ii) into the following equation.

Internal haze of optical film = (haze 2) - (haze 1)

In the above measurement, the following glass and glycerin were respectively used.

Glass: MICRO SLIDE GLASS S9213 MATSUNAMI

Glycerin: manufactured by Kantokagaku CICA Limited (purity> 99.0%) Refractive index 1.47

3) Measurement of external haze

The total haze measured in the above 1) and the internal haze calculated in the above 2) were substituted into the following equation to calculate the external haze.

Outside haze of optical film = (total haze) - (inside haze)

The evaluation results of the optical films 1 to 30 are shown in Table 3.

As shown in Table 3, the optical film in which the ultraviolet absorber and the antioxidant are localized on the surface (when Mc / Ms = 1), the ultraviolet absorber and the antioxidant were not localized on the surface (Mc / Ms = 1 (Higher than that of the optical films 1 to 5).

On the other hand, in the case of the optical film formed by the melt, the ultraviolet absorbing agent and the antioxidant are not localized on the surface (Mc / Ms = 1) and the adhesion to the polarizer is low (contrast of the optical films 24 and 15) . Likewise, an optical film not subjected to a solvent treatment shows a low adhesiveness to the polarizer (contrast of the optical films 29 and 15). Further, it is considered that the optical film 11 using the cycloolefin-based resin film 11 having a too large residual solvent amount hardly penetrates the solvent (of the treatment liquid) during the solvent treatment, and therefore the adhesiveness with the polarizer is lowered.

4. Fabrication of Liquid Crystal Display

<Fabrication of Liquid Crystal Display Device 1>

(Fabrication of first polarizing plate)

As a polarizer, a polarizer used for evaluation of the above-mentioned &quot; adhesive property to a polarizer &quot; was prepared. As the protective film F1, Konica Minolta Tact KC6UA (manufactured by Konica Minolta) was prepared. As the protective film F2, the above-prepared optical film 1 was prepared.

Then, the surface of KC6UA was alkali saponified under the following conditions. Specifically, KC6UA was immersed in a 1.5N sodium hydroxide aqueous solution at 55 ° C for 2 minutes, then washed in a wash bath at room temperature, and neutralized at 30 ° C using 0.1 N sulfuric acid. The obtained KC6UA was again washed in a washing bath at room temperature, and then dried with warm air at 100 ° C.

The alkali saponified KC6UA, the polarizer and the optical film 1 prepared above were bonded to each other via a 3 mass% aqueous solution of polyvinyl alcohol (PVA-117H manufactured by Kurara) as an aqueous adhesive, and a laminate of KC6UA / polarizer / optical film 1 &Lt; / RTI &gt; The bonding is performed such that one side of the polarizer is in contact with the saponified surface of KC6UA and the other side of the polarizer is in contact with the side of the optical film 1 having the modified region and the in-plane slow axis of the optical film 1 and the absorption axis of the polarizer are orthogonal . The resulting laminate was dried to obtain a polarizing plate 1 (first polarizing plate).

(Fabrication of liquid crystal display device)

As a liquid crystal display device, a liquid crystal TV "AQ-32AD5" manufactured by Sharp, a liquid crystal display device of the VA system, was prepared. The polarizing plate on the viewing side was peeled off from this apparatus, and the polarizing plate 1 prepared above was attached to the viewing side surface of the liquid crystal cell through a pressure sensitive adhesive to obtain a liquid crystal display device.

The attachment of the polarizing plate 1 is carried out in such a manner that the optical film 1 (protective film F2) is on the side of the liquid crystal cell, the absorption axis of the polarizer is perpendicular to the slow axis of the optical film 1, .

<Fabrication of Liquid Crystal Display Devices 2 to 30>

Liquid crystal display devices 2 to 30 were obtained in the same manner as in the production of the liquid crystal display device 1 except that the protective film F2 of the polarizing plate was changed as shown in Table 4. [

<Fabrication of Liquid Crystal Display Devices 31 to 32>

The liquid crystal display devices 31 to 32 were obtained in the same manner as in the production of the liquid crystal display device 1 except that the kinds of the protective films F1 and F2 of the polarizing plate were changed as shown in Table 4. [

The frontal contrast of the obtained liquid crystal display device was measured by the following method.

(Front Contrast)

The obtained liquid crystal display was subjected to continuous contrast-light measurement after continuously lighting the backlight for one week under an environment of 23 占 폚 and 55% RH. The front contrast was measured by using a device "CS-2000" manufactured by Konica Minolta Sensing, irradiating a light having a wavelength of 550 nm, and the luminance in the white display state and the black display state of the liquid crystal display device, Was measured from the normal direction of the display screen. Then, the obtained value was substituted into the following equation to calculate the front contrast (CR).

Front contrast (CR) = (luminance in the white display state) - (luminance in the black display state)

The value of the front contrast was evaluated based on the following criteria. △ was judged to be good.

?: 900? CR

?: 850? CR <900

?: 800? CR <850

×: 800> CR

The evaluation results of the liquid crystal display devices 1 to 32 are shown in Table 4.

As shown in Table 4, the optical films 1 to 3, 7 to 10, 12 to 16, 18 to 23, 25 to 28, 31 and 32 having Mc / Ms of less than 1, , The front contrast is good.

On the other hand, all of the optical films 4, 5 and 24 having Mc / Ms of 1 or more, the optical film 6 having a too small amount of residual solvent, the optical film 29 having too large an external haze ratio, The contrast unevenness due to the excessive increase of the external haze appears.

<Fabrication of Liquid Crystal Display Device 33>

As a liquid crystal display device, a liquid crystal TV "VIERA TH-26LX60" manufactured by Panasonic, an IPS type liquid crystal display device, was prepared. The polarizing plate on the viewing side was peeled off from this apparatus, and the polarizing plate 21 prepared above was attached to the viewing side of the liquid crystal cell through a pressure-sensitive adhesive to obtain a liquid crystal display device 33.

The attachment of the polarizing plate 21 is carried out in such a manner that the optical film 21 (protective film F2) is on the side of the liquid crystal cell, the absorption axis of the polarizer is orthogonal to the slow axis of the optical film 21, .

<Fabrication of Liquid Crystal Display Devices 34 to 36>

Liquid crystal display devices 34 to 36 were obtained in the same manner as in the production of the liquid crystal display device 32 except that the protective films F1 and F2 of the polarizing plate were changed as shown in Table 5. [

The frontal contrast of the obtained liquid crystal display device was evaluated by the above-mentioned method. The evaluation results of the liquid crystal display devices 33 to 36 are shown in Table 5.

As shown in Table 5, the liquid crystal display devices 33 and 34 using the optical film 21 in which the Mc / Ms in the optical film is less than 1 and the amount of the residual solvent is set to a certain amount or more appear to have a good contrast.

On the other hand, the liquid crystal display devices 35 and 36 using the optical film 24 obtained by the melt film formation and having Mc / Ms = 1 and no residual solvent show low contrast.

The present application claims priority based on Japanese Patent Application No. 2015-231919 filed on November 27, 2015. The contents of the present specification and drawings are all incorporated herein by reference.

According to the present invention, it is possible to provide an optical film having good durability and capable of suppressing a decrease in contrast of a liquid crystal display device.

10: Optical film
10A, 45A: modified region
20: Liquid crystal display
30: liquid crystal cell
40: First polarizing plate
41: First polarizer
43: Protective film (F1)
45: Protective film (F2)
50: second polarizer plate
51: second polarizer
53: Protective film (F3)
55: Protective film (F4)
60: Backlight

Claims (11)

An optical film having a modified region including a roughened surface,
Wherein the optical film contains at least one of a cycloolefin resin, an ultraviolet absorber and an antioxidant,
The total content of the ultraviolet absorber and the antioxidant in the region S from the harmonic surface to the position of 0.1 t in the thickness direction on the cut surface perpendicular to the surface of the optical film is Ms, When the total content of the ultraviolet absorber and the antioxidant in the region C from the center to the position of ± 0.1 t in the thickness direction is Mc (the thickness of the optical film is taken as t), Mc / Ms 0.01 or more and less than 1,
Wherein the amount of the residual solvent contained in the optical film is 100 ppm or more and 2000 ppm or less,
Internal haze: external haze = 1: 15 to 1: 1000. The method according to claim 1,
Wherein the external haze is 0.1 to 5%. 3. The method according to claim 1 or 2,
The content of the ultraviolet absorber is 0.5 to 5% by mass with respect to the cycloolefin resin. 4. The method according to any one of claims 1 to 3,
Wherein the residual solvent comprises 100 to 300 ppm of toluene. 5. The method according to any one of claims 1 to 4,
Wherein the Mc / Ms is 0.7 or less. 6. A polarizing plate comprising the optical film according to any one of claims 1 to 5 and a polarizer disposed on a surface on which the modified region is formed. A first polarizing plate, a liquid crystal cell, a second polarizing plate, and a backlight in this order,
The first polarizer includes a first polarizer, a protective film F1 disposed on a surface opposite to the liquid crystal cell of the first polarizer, and a protective film F2 disposed on the liquid crystal cell side surface of the first polarizer and,
The second polarizer includes a second polarizer, a protective film F3 disposed on the side of the liquid crystal cell side of the second polarizer, and a protective film F4 disposed on the side opposite to the liquid crystal cell of the second polarizer and,
Wherein at least one of the protective films F1 and F2 is the optical film according to any one of claims 1 to 5 and the first polarizer is disposed on a surface on which the modified region of the optical film is formed, /or
Wherein at least one of the protective films F3 and F4 is the optical film according to any one of claims 1 to 5 and the second polarizer is a liquid crystal film disposed on the surface on which the modified region of the optical film is formed, Display device. 8. The method of claim 7,
Wherein at least one of the protective films F1 and F2 is the optical film according to any one of claims 1 to 5 and the first polarizer is a liquid crystal film Display device. 1. A film comprising at least one of a cycloolefin resin, an ultraviolet absorber and an antioxidant, characterized in that, in the cut surface perpendicular to the surface, the ultraviolet light in the region S from the at least one surface to the position 0.1 t in the thickness direction When the total content of the ultraviolet absorber and the antioxidant in the region C from the center of the film to the position of ± 0.1 t in the thickness direction is Mc , A thickness of the film is referred to as t), a cycloolefin-based resin film having a Mc / Ms of 0.01 or more and less than 1, and a residual solvent amount of 100 ppm or more and 2000 ppm or less,
And a step of subjecting the surface of the cycloolefin resin film constituting the region S to a solvent treatment in contact with an organic solvent. 10. The method of claim 9,
In the step of obtaining the cycloolefin-based resin film,
A step of dissolving at least one of the cycloolefin resin, the ultraviolet absorber and the antioxidant in a solvent containing 70% by mass or more of a good solvent to obtain a dope;
A step of softening the dope on a support and then drying until the amount of the residual solvent becomes 1 to 10% by mass, thereby peeling off the resulting flexible film to obtain a film-
And drying the film to obtain a cycloolefin-based resin film. 11. The method of claim 10,
In the step of drying the filmy material to obtain a cycloolefin-based resin film, the filmy material is dried at 90 to 160 ° C.

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