JP2003039014A - Optical film, method for manufacturing the same, polarizing plate using the optical film and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film obtained by forming a coating layer on a transparent resin film and having high flatness, and a method for manufacturing the same. SOLUTION: The optical film is manufactured by applying a coating solution to a continuously fed resin film and drying the coating film while winding the same around a rotary support having a diameter larger than the width of the resin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical film used for optical applications and a method for producing the same, and particularly to an optical film useful for a polarizing plate protective film or an antireflection film, or a display device using the same. It is about.

[0002]

2. Description of the Related Art A transparent resin film used for optical applications such as a polarizing plate protective film for liquid crystal displays and a circular polarizing plate protective film used for organic EL displays and the like has several functions in order to have various functions. A functional layer is applied. For example, an antistatic layer for providing an antistatic function, a hard coat layer for improving the surface hardness, an undercoat layer for improving the film-forming property, an anti-curl layer for preventing curling, or an anti-curling layer. Examples include a glare layer and an antireflection layer. When coating such a functional layer on the transparent resin film, there is a problem that the flatness is deteriorated by the coating solvent. In particular, in the case of coating using an organic solvent, if the organic solvent used is a solvent that swells or dissolves the resin film, the influence thereof is great and the flatness of the optical film deteriorates. In particular, a polarizing plate or an antireflection film used on the front surface of a display device has severe performance requirements, and a film having more excellent flatness has been desired.

[0003]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical film having high flatness in a method for producing an optical film having a coating layer formed on a transparent resin film, and a method for producing the same. .

[0004]

The above object of the present invention can be achieved by the following constitutions.

(1) Manufacture of an optical film characterized in that a coating solution is applied onto a resin film which is continuously conveyed, and is dried while being wound on a rotary support having a diameter larger than the width of the resin film. Method.

(2) A method for producing an optical film, characterized in that a coating solution is applied onto a resin film which is continuously conveyed, and is dried while gripping the width.

(3) An optical method characterized in that a coating solution is applied onto a resin film which is continuously conveyed, and the resin film is wound on a rotary support having a diameter larger than the width of the resin film and dried while gripping the width. Film manufacturing method.

(4) The method for producing an optical film as described in any one of (1) to (3), wherein the coating liquid contains an organic solvent which dissolves or swells the resin film.

(5) The method for producing an optical film as described in (1) or (2), wherein the tension applied in the width direction is 0.5 to 1.5 times the conveyance tension.

(6) A coating solution containing an actinic ray-curing substance is applied onto a resin film which is continuously conveyed, and the actinic ray is irradiated while being wound on a rotary support having a diameter larger than the width of the resin film. A method for producing an optical film having an actinic radiation curable layer, comprising:

(7) Production of an optical film having an actinic ray-curable layer, characterized in that a coating solution containing an actinic ray-curing substance is applied onto a resin film which is continuously conveyed, and the actinic ray is radiated while gripping the width. Method.

(8) A coating solution containing an actinic ray-curing substance is applied onto a resin film which is continuously conveyed, and the actinic ray is wound while being wound on a rotary support having a diameter larger than the width of the resin film and grasping the width. A method for producing an optical film having an actinic ray-curable layer, which comprises irradiating.

(9) An optical film produced by the method according to any one of (1) to (8) above.

(10) An optical film, wherein the actinic radiation-cured layer is produced by the method according to any one of (6) to (8).

(11) The optical film as described in (1) 0, wherein the actinic radiation curable layer is a hard coat layer.

(12) The optical film as described in (10) or (11), wherein the actinic radiation curable layer is an optical interference layer.

(13) The resin film is a cellulose ester film (10) to (12)
The optical film according to any one of 1.

(14) The resin film has a thickness of 10 to 60 μm.
m is an optical film as described in any one of (10) to (13).

(15) A polarizing plate having the optical film according to any one of (10) to (14) on at least one surface.

(16) A display device using the optical film according to any one of (10) to (14).

(17) The coating method used in the method for producing an optical film according to any one of the above (1) to (8) is such that the running direction of the film is below a continuously conveyed belt-shaped resin film. And a gravure roll having a gravure pattern formed on the entire outer peripheral surface of a metal or ceramic material having a diameter of 20 mm to 50 mm and having a relative speed with respect to the resin film. While rotating at a peripheral speed, wipe off before applying the excess coating liquid from the surface of this gravure roll by a doctor blade, a fixed amount of coating liquid on the lower surface of the film at a position where the upper surface of the resin film is in a free state. It is a gravure coating method in which the resin film is applied and the coating liquid is evenly attached to the resin film. Coating method characterized in that it comprises means for preventing deformation at the width of the film before and after.

(18) As a means for ensuring the flatness, an expander roll is arranged before or after the resin film contacts the gravure roll (17).
The coating method described.

(19) The coating method according to (17) or (18), wherein the position of the roll that presses the film against the gravure roll is 20 mm or less with respect to the contact position of the gravure roll.

(20) A thin film having a dry film thickness of less than 0.2 μm is formed directly or through another layer on the resin film, according to any one of (17) to (19). Application method.

(21) The gravure pattern is an oblique line, and the opposite gravure pattern is arranged at the end on the side that becomes the tip of the gravure pattern and is applied (17).
~ The coating method according to any one of (20).

(22) The openings of the end gravure pattern are larger than the openings of the main coating area 17 to 2
1. The coating method according to any one of 1.

(23) The coating method according to any one of (17) to (22), characterized in that a ring-shaped groove is provided at the end of the gravure pattern.

(24) An optical film coated by the coating method according to any one of (17) to (23).

(25) The actinic radiation-curable layer has (17) to (2)
An optical film coated by the coating method according to any one of 3).

(26) The optical film as described in (25), wherein the actinic radiation curable layer is a hard coat layer.

(27) The optical film as described in (25) or (26), wherein the actinic radiation curable layer is an optical interference layer.

(28) The resin film is a cellulose ester film (25) to (27)
The optical film according to any one of 1.

(29) The resin film has a thickness of 10 to 60 μm.
m is an optical film as described in any one of (25) to (28).

(30) A polarizing plate having the optical film according to any one of (25) to (29) on at least one surface.

(31) A display device using the optical film described in any one of (25) to (29).

The present invention will be described in more detail below. The present invention is a method for producing an optical film, which comprises applying a coating liquid onto a resin film that is continuously conveyed, and drying the resin film while winding it on a rotating support having a diameter equal to or larger than the width of the resin film. . In particular, when the coating solution contains a solvent that dissolves or swells the resin film,
There is a problem that the flatness of the resin film deteriorates before the coating solvent dries. In particular, optical films used in various display devices and the like are required to have a high degree of flatness, and improvements thereof have been demanded. In order to solve this problem, the present inventors have diligently studied and, as a result, apply a coating solution onto a resin film that is continuously conveyed, while winding it on a rotating support having a diameter equal to or larger than the width of the resin film. By drying, an optical film excellent in flatness was obtained.

A preferred example will be described with reference to the drawings. 1 and 2 show a rotating support body in a drum shape, and FIG. 3 shows a rotating support body in which two drums are connected by a belt. In the present invention, the drum support shape is preferable.

FIG. 1 is a schematic view of a drying device using a drum-shaped rotating support, and FIG. 2 is a perspective view of the drying device. In the figure, the film applied by the die coater 3 to the continuously conveyed resin film 1 is quickly wound around the drum 2 and dried in the drying zone 6 while maintaining the flatness. Therefore, it is desirable that the diameter D of the drum is large, and it is necessary that the diameter is at least the width L of the resin film. More preferably, the length corresponding to 1 to 30 times the width L of the resin film is preferably dried in a state of being wound on the support. If the support is too large, uniform drying becomes difficult, and the equipment cost is too high to be practical. In the case of a drum, the diameter is preferably 1 to 15 times the width of the resin film, and if larger than that, a belt-shaped support is preferably used. FIG. 3 is a perspective view of a drying device using a rotating support body in which two drums 21 and 22 are connected by a belt 23.

In the present invention, the coating liquid is applied onto the resin film which is continuously conveyed, and the drum-shaped rotary support having a diameter equal to or larger than the width of the resin film or the circumference equivalent to the drum-shaped rotary support. In order to maintain flatness, it is preferable to dry 50% by mass or more, and more preferably 70% by mass or more of the coating solvent while winding the two drums having a long length on a rotating support by connecting with a belt. preferable.

There is also provided a method of manufacturing an optical film according to another embodiment of the present invention. That is, it is a method for producing an optical film, which comprises applying a coating liquid onto a resin film that is continuously conveyed and drying the resin film while gripping the width.

After applying the coating liquid on the resin film which is continuously conveyed, it is desirable that the resin film is quickly gripped by the width, or the width is gripped more than before the coating. It is particularly preferable to dry 50% by mass or more, more preferably 70% by mass or more of the coating solvent in order to maintain the flatness. By applying tension in the width direction by the width grip, it is possible to prevent the flatness of the resin film from being deteriorated during the drying process. When the coating liquid contains an organic solvent that dissolves or swells the resin film, the flatness can be improved more than before coating. The tension applied in the width direction when gripping the width is preferably 0.5 to 1.5 times the transport tension, and is preferably substantially equal to the transport tension. The width gripping can be performed by a tenter device, and it is particularly preferable to use a biaxially stretched tenter.

FIG. 4 is a schematic view of a drying device for drying while holding the width with a tenter. The resin film 1 is continuously conveyed while being held in the width by the tenter 41, coated with the coating liquid from the die coater 3, dried in the drying zone 6, and then released from the tenter clip by a releasing means (not shown).

FIG. 5 shows a concrete example of the tenter. (A)
Indicates a clip tenter 51, and a shoe 52 and a fixing base 5
3 has a structure for gripping the resin film 1, and (b) shows a pin tenter 54, in which a pin 55 fixed to a fixing base 56 pierces the resin film 1 to grip the resin film. Has become. The present invention is not limited to these, and various gripping means can be used.

In the present invention, more preferably, the coating liquid is applied on a resin film which is continuously conveyed, and the resin film is wound on a rotating support having a diameter larger than the width of the resin film and dried while gripping the width. And a method for producing an optical film. Preferred examples thereof are shown in FIGS. 6 and 7.
Shown in. FIG. 6 is a perspective view of a drying device using a drum-shaped rotating support body while gripping the width with the tenter used in the present invention, and FIG. 7 shows two drums while holding the width with the tenter used in the present invention. It is a schematic diagram of a drying device using a support body which is tied with a belt and rotates. That is, not only the flatness can be maintained by further gripping the width while winding it on a rotating support having a diameter equal to or larger than the width of the resin film and applying tension in the width direction, but also in a higher flat surface. It also has the effect of straightening it so that it becomes sexual.

The method for producing an optical film of the present invention is also useful when curing a curable resin or the like with actinic radiation. That is, the invention is characterized in that after applying a coating liquid containing an actinic ray-curing substance on a resin film and drying it, the actinic ray is irradiated while being wound on a rotating support having a diameter equal to or larger than the width of the resin film. It is a method for producing an optical film having an actinic radiation curable layer. The actinic radiation-cured layer has the property of shrinking during curing, but it is also excellent in flatness after curing by irradiating it with actinic radiation while winding it on a rotating support having a diameter greater than the width of the resin film. Optical film can be obtained. More preferably, the length in contact with the rotating support is preferably 1 to 30 times the width of the resin film, and the actinic ray is irradiated on the same support after the above-mentioned coating solution is dried. Is more preferable.

The present invention also provides another embodiment. That is, it is a method for producing an optical film having an actinic ray-curable layer, which comprises applying a coating solution containing an actinic ray-curing substance onto a resin film that is continuously conveyed and irradiating the actinic ray while gripping the width. The width gripping is preferably performed by the same method as described above, and it is preferable that the actinic ray is irradiated subsequent to the drying of the coating solvent described above. Alternatively or additionally, a coating solution containing an actinic ray-curing substance is applied onto the resin film, and the actinic ray is irradiated while being wound on a rotating support having a diameter equal to or larger than the width of the resin film and grasping the width. By the method for producing an optical film having an actinic ray-curable layer, an optical film having an actinic ray-cured layer having further excellent flatness can be obtained. As the actinic radiation curable layer, one having an ultraviolet curable substance is particularly preferable, and it is particularly useful when a clear hard coat layer or an antiglare layer or an antireflection layer composed of a plurality of optical interference layers, an antistatic layer, or the like is applied. Is. As a means for irradiating with actinic rays, the actinic ray irradiation device 4 is shown in FIGS. 1 to 4 and FIGS.

The resin film used in the present invention is not particularly limited, and examples thereof include transparent resin films such as polyester film, polyethylene film, polypropylene film, cellophane, cellulose diacetate film, cellulose acetate butyrate film and cellulose acetate propionate. Film, film made of cellulose triacetate or cellulose derivative, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, polycarbonate film, norbornene resin film, polymethylpentene film, polyetherketone film,
Examples thereof include polyether sulfone film, polysulfone film, polyether ketone imide film, polyamide film, fluororesin film, nylon film, polymethylmethacrylate film, acrylic film and polyarylate film. On the other hand, an excellent effect can be expected especially for a film in which the resin film has a cellulose ester. This is because the cellulose ester film has additives such as a plasticizer and has a property of being easily dissolved or swelled by a coating solvent. Examples of the cellulose ester film include a cellulose acetate film, a cellulose acetate butyrate film, a cellulose acetate propionate film, and a cellulose triacetate (TAC). In particular, the influence is remarkable in a thin film having a film thickness of 10 to 60 μm, and the method of the present invention can exhibit excellent effects as a method for producing an optical film that requires a high degree of flatness.

The method for forming the cellulose ester film will be described below. Cellulose ester film is generally prepared by dissolving cellulose ester flake raw material and a plasticizer in methylene chloride to form a viscous liquid, and dissolving the plasticizer in the dope to form a dope. From an extruder die, endlessly rotating stainless steel, etc. Cast on a metal belt (also called a band), dried, peeled from the belt in a dry state, and conveyed by a conveyor such as a roll.
It is made by drying from both sides and winding. The cellulose ester film used in the production of the optical film of the present invention is one in which the end portion of the film is gripped by a device such as a tenter in the drying process and a width is retained or stretched by applying tension in the width direction. It is preferable because higher flatness can be obtained.

The cellulose ester resin of the cellulose ester film used for producing the optical film of the present invention is preferably a lower fatty acid ester resin of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose is preferably a fatty acid having 6 or less carbon atoms, and for example, cellulose acetate, cellulose propionate, cellulose butyrate and the like are mentioned as particularly preferable examples of the lower fatty acid ester of cellulose.

In addition to the above, JP-A-10-458 is also available.
04, 8-231761, U.S. Pat. No. 2,31
Mixed fatty acid esters such as cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate propionate butyrate described in No. 9,052 can be used. Among the above-mentioned, the most preferable lower fatty acid ester of cellulose is cellulose triacetate (hereinafter referred to as TAC) or cellulose acetate propionate.

The number average molecular weight of the cellulose ester according to the present invention is preferably 70,000 to 250,000, since it has a high mechanical strength when molded and gives an appropriate dope viscosity, more preferably 80,000 to 150. 1,000
Is.

The cellulose ester used in the present invention has an acetyl group and / or a propionyl group as a substituent, and when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group is Y, the following formula ( I) and (II)
Particularly preferred is a cellulose ester that simultaneously satisfies

(I) 2.5.ltoreq.X + Y.ltoreq.3.0 (II) 0.ltoreq.Y.ltoreq.1.2 The method for measuring the degree of substitution of the acyl group is ASTM-D817-9.
It can be measured according to the regulations of 6.

As the cellulose ester, either a cellulose ester synthesized from cotton linter or a cellulose ester synthesized from wood pulp can be used alone or in a mixture at an arbitrary ratio. If the peelability from the belt or drum becomes a problem, it is preferable to use a large amount of a cellulose ester synthesized from cotton linter, which has good peelability from the belt or drum, because the productivity is high. When a cellulose ester synthesized from wood pulp is mixed and used, the ratio of the cellulose ester synthesized from cotton linter is 40% by mass or more, and the effect of releasability becomes remarkable, so that 60% by mass or more is further preferable. Preferably, it is most preferably used alone.

The solvent used for preparing the dope may be any solvent as long as it can dissolve the cellulose ester, and even a solvent that cannot be dissolved alone can be dissolved by mixing with another solvent. Can be used if Generally, a mixed solvent containing a good solvent, methylene chloride, and a poor solvent for cellulose ester is used, and the mixed solvent preferably contains 4 to 30% by mass of the poor solvent.

Other good solvents that can be used include, for example, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2.
-Trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, 1,3-difluoro-2-
Propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3
3,3-hexafluoro-2-propanol, 2,2
Examples of the organic solvent include 3,3,3-pentafluoro-1-propanol and nitroethane, but organic halogen compounds such as methylene chloride, dioxolane derivatives, methyl acetate, ethyl acetate and acetone are preferable organic solvents (that is, good solvents). ).

Examples of the poor solvent for cellulose ester include methanol, ethanol, n-propanol and is
Examples thereof include alcohols having 1 to 8 carbon atoms such as o-propanol, n-butanol, sec-butanol, and tert-butanol. These poor solvents may be used alone or in combination of two or more kinds. .

The plasticizer that can be used in the present invention is not particularly limited, but is a phosphoric acid ester plasticizer, a phthalic acid ester plasticizer, a trimellitic acid ester plasticizer, a pyromellitic acid plasticizer, or a glycolate. Plasticizer,
A citric acid ester-based plasticizer, a polyester-based plasticizer, or the like can be used.

In the phosphoric acid ester system, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate,
Diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc., in the phthalate ester system, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate,
Dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, diphenyl phthalate, etc. as trimellitic acid plasticizers, such as tributyl trimellitate, triphenyl trimellitate, triethyl trimellitate, pyromellitic acid ester plasticizers As, tetrabutylpyromellitate, tetraphenylpyromellitate, tetraethylpyromellitate, etc., in glycolic acid ester series, triacetin, tributyrin, ethylphthalylethylglycolate, methylphthalylethylglycolate, butylphthalylbutylglycolate. As citric acid ester plasticizers, triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-n-butyl citrate, acetyl tri-n. (2-ethylhexyl) citrate and the like can be preferably used. As the polyester plasticizer, a copolymer of a dibasic acid such as an aliphatic dibasic acid, an alicyclic dibasic acid and an aromatic dibasic acid and a glycol can be used. The aliphatic dibasic acid is not particularly limited, but adipic acid, sebacic acid, phthalic acid, terephthalic acid, 1,4-cyclohexyldicarboxylic acid and the like can be used.

As glycols, ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-
Butylene glycol or the like can be used. These dibasic acids and glycols may be used alone or in combination of two or more. The weight average molecular weight of the polyester is preferably in the range of 500 to 2000 from the viewpoint of compatibility with the cellulose ester.

In the present invention, it is particularly preferable to use a plasticizer having a vapor pressure of less than 1333 Pa at 200 ° C., more preferably a compound having a vapor pressure of 666 Pa or less, further preferably 1 to 133 Pa. The non-volatile plasticizer is not particularly limited, and examples thereof include arylene bis (diaryl phosphate) ester, tricresyl phosphate, tri (2-ethylhexyl) trimellitate, and the above polyester plasticizers.

These plasticizers can be used alone or in combination of two or more kinds. Considering dimensional stability and processability, the amount of the plasticizer used can be added in an amount of 1 to 40% by mass with respect to the cellulose ester, and the amount of 3 to 20
It is preferably added in the range of mass%, and more preferably 4 to 15 mass%. If the amount is less than 3% by mass, a smooth cut surface cannot be obtained when slitting or punching, and chips are often generated.

It is preferable to add an antioxidant or an ultraviolet absorber to the cellulose ester film of the present invention.

As the above antioxidant, hindered phenol compounds are preferably used, and 2,6-di-t is used.
-Butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5) -Methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4]
-Hydroxyphenyl) propionate], 2,4-bis (n-octylthio) -6- (4-hydroxy-3,
5-di-t-butylanilino) -1,3,5-triazine, 2,2-thiodiethylenebis [3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate, N, N'-
Hexamethylenebis (3,5-di-t-butyl-4-hydroxyhydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4)
-Hydroxybenzyl) benzene, tris- (3,5-
Di-t-butyl-4-hydroxybenzyl) isocyanurate and the like can be mentioned. Especially 2,6-di-t-butyl-
p-cresol, pentaerythrityl-tetrakis [3
-(3,5-di-t-butyl-4-hydroxyphenyl) propionate] and triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] are preferred. Also, for example,
N, N'-bis [3- (3,5-di-t-butyl-4-
Hydrazine-based metal deactivators such as hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-t-
A phosphorus-based processing stabilizer such as butylphenyl) phosphite may be used in combination. The addition amount of these compounds is preferably 1 ppm to 1.0% by mass ratio with respect to the cellulose ester, and more preferably 10 to 1000 ppm.

In addition to the above, heat stabilizers such as inorganic fine particles such as kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide and alumina, and salts of alkaline earth metals such as calcium and magnesium are added. May be.

The cellulose ester film of the present invention comprises
Because of its high dimensional stability, it is used for polarizing plates, liquid crystal display members and the like, but ultraviolet absorbers are preferably used from the viewpoint of preventing deterioration of polarizing plates, liquid crystals and the like.

As the ultraviolet absorber, those having excellent absorption of ultraviolet rays having a wavelength of 370 nm or less and little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display property. Specifically, the transmittance at 380 nm is preferably less than 10%, and more preferably less than 5%.

Specific examples of the ultraviolet absorber preferably used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylate compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex salt compounds and the like. To be
Further, JP-A-6-148430 and JP-A-12-27343.
The polymer ultraviolet absorber described in 7 is also preferably used. Alternatively, the ultraviolet absorber described in JP-A-10-152568 may be used.

As the benzotriazole type ultraviolet absorber, a compound represented by the following general formula [1] is preferably used.

[0070]

[Chemical 1]

In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different and each represents a hydrogen atom, a halogen atom, a nitro group, a hydroxyl group, an alkyl group, an alkenyl group, an aryl group or an alkoxyl group. Represents a group, an acyloxy group, an aryloxy group, an alkylthio group, an arylthio group, a mono- or dialkylamino group, an acylamino group or a 5- or 6-membered heterocyclic group, and R ₄ and R ₅ are ring-closed to form a 5- or 6-membered carbon. You may form a ring.

Further, these groups described above may have an arbitrary substituent. Specific examples of the ultraviolet absorbent according to the present invention will be given below, but the present invention is not limited thereto.

UV-1: 2- (2'-hydroxy-5 '
-Methylphenyl) benzotriazole UV-2: 2- (2'-hydroxy-3 ', 5'-di-
tert-Butylphenyl) benzotriazole UV-3: 2- (2'-hydroxy-3'-tert-
Butyl-5'-methylphenyl) benzotriazole UV-4: 2- (2'-hydroxy-3 ', 5'-di-
tert-Butylphenyl) -5-chlorobenzotriazole UV-5: 2- (2'-hydroxy-3 '-(3 ",
4 ", 5", 6 "-tetrahydrophthalimidomethyl)
-5'-Methylphenyl) benzotriazole UV-6: 2,2-methylenebis (4- (1,1,3,3)
3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) UV-7: 2- (2'-hydroxy-3'-tert-
Butyl-5'-methylphenyl) -5-chlorobenzotriazole UV-8: 2- (2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol (TINUVIN171, Ciba) Specialty Chemicals Co., Ltd.) UV-9: Octyl-3- [3-tert-butyl-4]
-Hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazole- Two
-Yl) phenyl] propionate mixture (TINU
VIN109, Ciba Specialty Chemicals Co., Ltd.
(Production) Specific examples of the benzophenone-based ultraviolet absorber are shown below, but the present invention is not limited thereto.

UV-10: 2,4-dihydroxybenzophenone UV-11: 2,2'-dihydroxy-4-methoxybenzophenone UV-12: 2-hydroxy-4-methoxy-5-sulfobenzophenone UV-13: bis ( 2-methoxy-4-hydroxy-5
-Benzoylphenylmethane) In the cellulose ester film used in the present invention,
It is preferable to add fine particles in order to impart slipperiness to the film and prevent blocking of the roll-shaped film.

The fine particles according to the present invention include fine particles of an inorganic compound or fine particles of an organic compound.

As the inorganic compound, a compound containing silicon,
Preferred are silicon dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate, and more preferably silicon. Although it is an inorganic compound or zirconium oxide, silicon dioxide is particularly preferably used because it can reduce the turbidity of the cellulose ester laminated film.

As the fine particles of silicon dioxide, for example, Aerosil R972, R972V, R974, R812,
200, 200V, 300, R202, OX50, TT
Commercial products such as 600 (all manufactured by Nippon Aerosil Co., Ltd.) can be used.

As fine particles of zirconium oxide, commercially available products such as Aerosil R976 and R811 (all manufactured by Nippon Aerosil Co., Ltd.) can be used.

As the organic compound, for example, polymers such as silicone resin, fluorine resin and acrylic resin are preferable, and among them, silicone resin is preferably used.

Among the silicone resins described above, those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 1
Commercially available products having trade names such as 45, 3120 and 240 (all manufactured by Toshiba Silicone Co., Ltd.) can be used.

The primary average particle diameter of the fine particles according to the present invention is preferably 20 nm or less, more preferably 5 to 16 nm, from the viewpoint of suppressing haze to a low level.
Particularly preferably, it is 5 to 12 nm. For example, they are commercially available under the trade names of Aerosil 200V and Aerosil R972V (all manufactured by Nippon Aerosil Co., Ltd.), and they can be preferably used.

<< Preparation Method A >> A solvent and fine particles are mixed by stirring and then dispersed by a disperser. This is referred to as a fine particle dispersion liquid. The fine particle dispersion liquid is added to the dope liquid and stirred.

<< Preparation Method B >> The solvent and the fine particles are mixed by stirring and then dispersed by a disperser. This is referred to as a fine particle dispersion liquid. Separately, a small amount of cellulose ester is added to the solvent and dissolved by stirring. As the cellulose ester added here,
It is particularly preferred to add the solids of the invention.

The fine particle dispersion is added to this and stirred. This is used as a fine particle addition liquid. The fine particle added liquid is thoroughly mixed with the dope liquid by an in-line mixer.

<< Preparation Method C >> A small amount of cellulose ester is added to a solvent and dissolved by stirring. Fine particles are added to this and dispersed by a disperser. This is used as a fine particle addition liquid. The fine particle added liquid is thoroughly mixed with the dope liquid by an in-line mixer.

Preparation method A is excellent in dispersibility of silicon dioxide fine particles, and preparation method C is excellent in that silicon dioxide fine particles are less likely to reaggregate. Above all, the above-mentioned preparation method B is a preferable preparation method which is excellent in both the dispersibility of the silicon dioxide fine particles and the difficulty of re-aggregation of the silicon dioxide fine particles.

<< Dispersion Method >> When the fine particles of silicon dioxide are mixed and dispersed with a solvent or the like, the concentration of silicon dioxide is 5 to 30.
Mass% is preferable, 10-25 mass% is more preferable, and 15-20 mass% is the most preferable. The higher the dispersion concentration, the more the liquid turbidity with respect to the added amount tends to be low, and the haze and the aggregates are improved, which is preferable.

The solvent used is a lower alcohol, preferably methyl alcohol, ethyl alcohol,
Propyl alcohol, isopropyl alcohol, butyl alcohol and the like can be mentioned. The solvent other than the lower alcohol is not particularly limited, but it is preferable to use the solvent used when forming the cellulose ester film.

The addition amount of silicon dioxide fine particles to cellulose ester is preferably 0.01 to 0.3 parts by weight, more preferably 0.05 to 0.2 parts by weight, based on 100 parts by weight of cellulose ester. , 0.
Most preferably, it is 08 to 0.12 parts by mass. The larger the added amount is, the more excellent the dynamic friction coefficient is, and the smaller the added amount is, the lower the haze is, and the smaller the number of aggregates is.

As the disperser, an ordinary disperser can be used. Dispersers are roughly divided into media dispersers and medialess dispersers. A medialess disperser is preferable for dispersing silicon dioxide fine particles because of its low haze.

Examples of the media disperser include a ball mill, a sand mill and a dyno mill.

As the medialess disperser, there are an ultrasonic type, a centrifugal type, a high pressure type and the like. In the present invention, a high pressure dispersing device is preferable. The high-pressure dispersing device is a device that creates special conditions such as high shear and high-pressure state by passing a composition obtained by mixing fine particles and a solvent at high speed through a thin tube. When treated with a high-pressure dispersion device, for example, the tube diameter is 1 to 2000 μm.
Maximum pressure condition inside the device is 9.807MP
It is preferably a or more. More preferably 19.6
It is 13 MPa or more. At that time, the maximum arrival speed is 1
Heat transfer rate of 420kJ /
Those that reach the time or more are preferable.

The high-pressure dispersing device as described above has a Micro
There is an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by fluidics Corporation or a nanomizer manufactured by Nanomizer Co., Ltd. In addition, there is a Manton-Gaulin type high-pressure disperser, for example, Izumi Food Machinery homogenizer, Sanwa Machinery Co., Ltd. UHN- 01 etc. are mentioned.

Further, although these fine particles may be uniformly distributed in the thickness direction of the film, it is more preferable that they are mainly distributed mainly in the vicinity of the surface, for example, co-casting. According to the method, it is preferable to use two or more types of dope and to add the fine particles to the dope mainly arranged on the surface layer side, since a film having high slipperiness and low haze can be obtained. Preferably, it is preferable to use at least one dope on the surface side or two dopes on the surface side by using three types of dopes, and mainly add fine particles to the dope forming the central layer. ,
It is preferably not included at all. Additives such as plasticizers or UV absorbers that may cause bleed-out are mainly added to the dope forming the central layer, and the two dopes on the surface side are added to the dope forming the central layer. The addition amount is preferably less than 80% by mass, more preferably less than 50% by mass, and it is more preferable to add almost no or not to prevent process contamination.

A coating layer can be provided by the method for producing an optical film of the present invention after the cellulose ester film obtained by the film-forming process is wound up once or continuously without being wound up.

The coating layer provided by the method for producing an optical film of the present invention is a layer provided for imparting various functions to the optical film, for example, an antiblocking layer,
Examples thereof include an antiglare layer, an antireflection layer, a clear hard layer, an antistatic layer, an anti-curl layer, an easy adhesion layer, an alignment layer, a liquid crystal layer, an optically anisotropic layer and an optical compensation layer. An organic solvent is preferably used for the coating liquid used to impart these various functions. At this time, it is preferable to use a solvent having a property of dissolving or swelling the resin film because of excellent adhesion between the coated layer and the resin film. On the other hand, it is possible to obtain by using such a solvent. There is a problem that the flatness of the optical film is significantly reduced.

According to the method for producing an optical film of the present invention, an optical film having high flatness can be obtained without deteriorating the flatness due to these solvents. Organic solvents that can be used as the coating liquid include methanol, ethanol, propanol, n-butanol, and 2
-Alcohols such as butanol, tert-butanol and cyclohexanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone and acetone, esters such as ethyl acetate, methyl acetate, ethyl lactate, isopropyl acetate, amyl acetate and ethyl butyrate, glycol ethers (Propylene glycol mono (C1-C4) alkyl ether (specifically propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, propylene glycol monobutyl ether) Etc.), propylene glycol mono (C1-C4) alkyl ether ester (propylene glycol monomethyl ether acetate Propylene glycol monoethyl ether acetate)), toluene, benzene, cyclohexane, and other solvents hydrocarbons such as n- hexane. Although not particularly limited to these, a solvent in which these are appropriately mixed is preferably used.

The method for applying the coating solution according to the present invention is a doctor coat, an extrusion coat, a slide coat, a roll coat, a gravure coat, a wire bar coat, a reverse coat, a curtain coat, an extrusion coat or US Pat. No. 2,681. It can be applied by an extrusion coating method using a hopper described in Japanese Patent No. 294,294.

Among these various functional layers, especially the layer formed by irradiating with actinic rays and curing, the flatness sometimes deteriorates. Therefore, as a result of repeated intensive studies to solve this problem, a coating solution containing an actinic ray-curing substance was applied and dried on the resin film, while being wound on a rotating support having a diameter equal to or larger than the width of the resin film. It was found that by irradiating with actinic rays, an optical film having an actinic ray-cured layer having excellent flatness can be obtained.

In another embodiment, it is confirmed that the flatness can be improved by applying a coating solution containing an actinic ray-curing substance on a resin film and irradiating the actinic ray while gripping the width. It was More preferably, a coating solution containing an actinic ray-curing substance is applied onto the resin film, and the actinic ray is radiated while being wound on a rotating support having a diameter equal to or larger than the width of the resin film and grasping the width, resulting in a flatter surface. Thus, an optical film having an actinic radiation curable layer having excellent properties was obtained.

The layer constitution of the optical film obtained by the production method of the present invention includes the following examples, but the layer constitution is not particularly limited thereto. Among these, the clear hard coat layer, the antiglare layer, the medium refractive index layer, the high refractive index layer and the low refractive index layer are applied and dried, and then irradiated with ultraviolet rays to be cured. Back coat layer / resin film / clear hard coat layer / high refractive index layer / low refractive index layer Back coat layer / resin film / clear hard coat layer / medium refractive index layer / high refractive index layer / low refractive index layer antistatic layer / Resin film / Clear hard coat layer / Medium refractive index layer / High refractive index layer / Low refractive index layer Back coat layer / Resin film / Anti-glare layer / High refractive index layer /
Low refractive index layer Back coat layer / Resin film / Anti-glare layer / Medium refractive index layer /
High Refractive Index Layer / Low Refractive Index Layer Antistatic Layer / Resin Film / Antiglare Layer / Medium Refractive Index Layer / High Refractive Index Layer / Low Refractive Index Layer Further about the coating composition according to the present invention An example will be described. The actinic ray curable resin layer means a layer containing a resin which is cured by a crosslinking reaction or the like by irradiation with actinic rays such as ultraviolet rays and electron beams as a main component. Typical examples of the actinic ray curable resin include an ultraviolet curable resin and an electron beam curable resin, but a resin which is cured by irradiation with an actinic ray other than ultraviolet rays and electron beams may be used. Examples of the ultraviolet curable resin include an ultraviolet curable acrylic urethane resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin,
A UV-curable polyol acrylate resin, a UV-curable epoxy resin or the like can be used.

The ultraviolet curable acrylic urethane resin is
In general, a product obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer is further added to 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate (hereinafter, acrylate includes only acrylate to include methacrylate), It can be easily obtained by reacting an acrylate-based monomer having a hydroxyl group such as 2-hydroxypropyl acrylate (for example, JP-A-59).
-151110).

The UV-curable polyester acrylate resin can generally be easily obtained by reacting a polyester polyol with 2-hydroxyethyl acrylate or 2-hydroxy acrylate monomer (for example, JP-A-59-151112). ).

As a specific example of the UV-curable epoxy acrylate resin, an epoxy acrylate as an oligomer, to which a reactive diluent and a photoreaction initiator are added and reacted (for example, Kaihei 1
-105738). As the photoreaction initiator, one or more selected from benzoin derivatives, oxime ketone derivatives, benzophenone derivatives, thioxanthone derivatives and the like can be used.

Specific examples of the UV-curable polyol acrylate resin include trimethylol propane triacrylate, ditrimethylol propane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate and alkyl-modified dipenta. Examples thereof include erythritol pentaacrylate. These resins are usually used together with a known photosensitizer. The above photoreaction initiator can also be used as a photosensitizer. Specifically, acetophenone, benzophenone,
Examples thereof include hydroxybenzophenone, Michler's ketone, α-amyloxime ester, tetramethyluram monosulfide, thioxanthone and their derivatives. Further, when the epoxy acrylate-based photoreactive agent is used, a sensitizer such as n-butylamine, triethylamine or tri-n-butylphosphine can be used. The photoreaction initiator or photosensitizer used in the ultraviolet curable resin composition is 0.1 to 1 with respect to 100 parts by mass of the composition.
It is 5 parts by mass, preferably 1 to 10 parts by mass.

As a light source for forming a hardened layer by photo-curing a UV-curable resin, any light source that emits UV light can be used. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a super high pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, etc. can be used. Irradiation conditions vary depending on each lamp, but the amount of irradiation light is 20 to 10,000 mJ / cm
^It may be about ² and preferably 50 to 2000 mJ /
cm ² . From the near-ultraviolet region to the visible light region, it can be used by using a sensitizer having an absorption maximum in that region.

Inorganic or organic fine particles are added to the cured layer in order to impart an antiglare property to the surface of the display panel, prevent adhesion to other substances, or impart scratch resistance. You can also For example, as the inorganic particles, silicon oxide, titanium oxide, aluminum oxide,
Examples thereof include tin oxide, zinc oxide, calcium carbonate, barium sulfate, talc, kaolin, calcium sulfate, and the like, and as the organic particles, polymethacrylic acid methyl acrylate resin powder, acrylic styrene resin powder,
Polymethylmethacrylate resin powder, silicon resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, Alternatively, it can be added to an ultraviolet curable resin composition such as polyfluorinated ethylene resin powder. The average particle size of these particle powders is 0.01 μm to 10 μm, and the ratio of the ultraviolet curable resin composition to the fine particle powder is the resin composition 1
It is desirable to add 0.1 to 20 parts by mass to 00 parts by mass. In order to impart the antiglare effect, the average particle size is preferably 0.1 to 1 μm, and 1 to 15 parts by mass is suitable for 100 parts by mass of the resin composition.

Furthermore, as the one having the function of preventing blocking, particles having a volume average particle diameter of 0.005 to 0.1 μm and the same components as described above are added in an amount of 0.1 to 5 with respect to 100 parts by mass of the resin composition. A mass part can also be used together.

Since the organic solvent contained in the coating liquid is evaporated before being irradiated with ultraviolet rays, a drying step is required.

As a method for applying the coating liquid having an actinic ray-curable substance, known methods such as a gravure coater, a spinner coater, a wire bar coater, a roll coater, a reverse coater, an extrusion coater and an air doctor coater can be used. The coating amount is 0 in wet film thickness.
1 to 30 μm is suitable, and preferably 0.5 to 15 μm
Is.

The coating solution containing the ultraviolet-curing substance is applied and dried, and then irradiated with ultraviolet rays.
5 minutes is preferable, and 3 seconds to 2 minutes is more preferable from the viewpoint of curing efficiency and work efficiency of the ultraviolet curable resin.

Since the optical film obtained by the present invention is excellent in flatness, it is particularly suitable for liquid crystal display devices or organic EL devices.
It is useful as an anti-reflection film or anti-glare film used for the front surface of L displays and plasma displays, and as a clear hard coat film, and can provide excellent visibility, and a polarizing plate using these as a polarizing plate protective film or A display device can be provided.

The method for applying the coating solution is not particularly limited in the present invention, but the present invention also provides a method for forming a thin film having a uniform film thickness. That is, a metal having a diameter of 20 mm to 50 mm, which is one of the gravure coating systems, is disposed below a continuously conveyed belt-shaped resin film so that the running direction of the film is orthogonal to the axial direction. Or a gravure roll having a gravure pattern formed on the entire circumference of the outer peripheral surface made of a ceramic material is rotated at a peripheral speed having a relative speed with the resin film,
The excess coating liquid is wiped off from the surface of this gravure roll by a doctor blade, and a fixed amount of the coating liquid is applied to the lower surface of the film at a position where the upper surface of the resin film is in a free state, and the resin film The method is a gravure coating method in which the coating liquid is uniformly applied to the coating solution, and has a means for preventing the resin film from being deformed by the width of the resin film before and after the contact with the gravure roll.

It is generally practiced to use diagonal lines as the gravure pattern. However, as the roll rotates, a liquid flow occurs in the direction of the gravure pattern. As the liquid is drawn to the central part of the resin film, air is entrained, and the bubbles often move to cause a bubble failure.

In particular, in the case of a low-viscosity liquid having a coating liquid of 10 cp or less, it spreads to the outside of the resin film at the end portion, the liquid pool is reduced at the coating end portion, and the entrainment of air becomes remarkable.

The present invention provides a coating method free of foam failure because foam failure is a serious failure in optical films used for optical applications.

[0117] In order to obtain uniform coating, it is necessary to form diagonal lines, but since the gravure pattern moves in one direction at the contact position of the resin film by rotation, the liquid moves in the width direction. On the side where the gravure eyes start, no liquid is supplied and the surface tension spreads to the outside of the gravure eyes, so that the liquid moves to suck air from the end of the liquid reservoir and form bubbles.

The air inhalation can be eliminated by reversing the direction of the eyes of the gravure pattern to spread the liquid on the end portions.

By enlarging the gravure pattern at the end portion, it is possible to prevent the suction of bubbles by supplying a liquid larger than the amount of movement to the central portion.

Further, by forming the ring-shaped groove at the end, it is possible to prevent the liquid from spreading to the outside and to supply the liquid so as not to suck the air when the liquid moves in the width direction. It is possible to prevent foam failure.

FIG. 8 is a roll bottom view showing an example of the oblique-line gravure pattern applied to the gravure roll. FIG. 3A shows the simplest shaded gravure pattern 60, and a liquid pool 63 is formed on the contact surface between the resin film 61 and the gravure roll 62 that continuously run, and coating is performed. Each arrow is the running direction of the resin film,
It indicates the direction of rotation of the gravure roll, and indicates that they travel in opposite directions. In the case of a low-viscosity coating liquid, the bubbles 64 are easily entrained, but in the figure (b), the end of the gravure pattern has a width of 20 mm and the gravure pattern 65 has diagonal lines with the same openings, (C) shows a ring-shaped groove 66 having the same opening formed at the end of the gravure pattern, and (d) shows a gravure pattern having an opening 20 mm at the end of the gravure pattern, the opening being twice the size of the main coating area. 6
The one with a diagonal line of 7 is shown.

FIG. 9 shows a schematic sectional view of a gravure coating apparatus used in the coating method of the present invention. The expander rolls 81 and 82 are installed in front of and behind the inlet support roll 83 and the outlet support roll 84 to ensure flatness. Roll contact with gravure is kiss-touch with the gravure roll 85 having a diameter of 20 mm to 50 mm, so if the flatness of the film on the inlet side is not ensured, wrinkles easily occur, and the contact state with the roll does not occur even if wrinkles do not occur. Since they are different, the transfer to the film is not uniform and a film thickness distribution occurs.

Further, when the film itself has a deformation, there is a problem that the deformation cannot be completely corrected because the holding angle on the gravure roll is shallow. Stable contact is possible by ensuring the flatness upstream of the coating part and making it enter the coating part.

That is, it was found that the uniformity of the film thickness of the obtained coating film is improved by preventing the resin film from being deformed in the width before and after the contact with the gravure roll. As shown in FIG. 7A, as a means for preventing the resin film from being deformed in the width direction, the expander rolls 81 and 82 are arranged before or after the resin film 1 contacts the gravure roll 85. or,
As another method, the position of the support rolls 83 and 84 for pressing the resin film against the gravure roll 85 is made significantly narrower than the conventional position with respect to the contact position of the gravure roll 85 to be 0.5 to 20 mm. Fine waviness in the direction is prevented and the uniformity of the film thickness of the coating film is improved. It is more preferable to combine these. In particular, when forming an extremely thin film having a dry film thickness of less than 0.2 μm, it is possible to significantly reduce the film thickness unevenness in the width direction.

A portion of the resin film in contact with the gravure roll is provided with a cover as long as it does not hinder the transport of the film.
It is preferable to prevent evaporation of the coating solvent or eliminate the influence of moisture absorption from the outside air. FIG. 9B shows a schematic sectional view of a gravure coating apparatus provided with a cover box for preventing evaporation of the coating solvent and moisture absorption from the outside air. The cover box is divided into upper and lower parts, and the lower part 89 is a box surrounding the gravure roll 85. The cover box is installed under the film and provided in the vicinity of the gravure roll surface to suppress evaporation of the roll surface after coating. The upper portion 88 surrounds the coating portion so as to cover the film. Further, it is preferable that the support roll, the expander roll, the cover, and the like are integrated with each other and can be retracted upward as shown in the drawing at the end of coating.

These cover boxes are effective especially when the coating liquid is affected by water absorption, and it is possible to circulate the coating liquid, but it is necessary to constantly supply a new liquid and circulate and use the coating liquid. Good.

[0127]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. First, each composition used in the examples will be described.

Example 1 <Preparation of transparent resin film 1> (Dope composition (a)) Cellulose triacetate (acetyl substitution degree 2.88) 100 parts by mass Ethylphthalylethyl glycolate 6 parts by mass Tinuvin 171 (Ciba Specialty Chemicals) Co., Ltd.) 2 parts by mass Silicon oxide fine particles (Aerosil 200V) 0.1 parts by mass Methylene chloride 430 parts by mass Methanol 90 parts by mass The above composition is put into a closed container, kept at 80 ° C. under pressure and stirred. While completely dissolved.

The dope is then filtered, cooled to 33 ° C.
The solution was uniformly cast on a stainless steel band, and the solvent was evaporated until peeling became possible. After peeling from the stainless band, it was dried while holding the width with a tenter and 1.05 times in the width direction. The film is stretched so that the film thickness is 4
A 0 μm transparent resin film 1 was obtained.

The surface in contact with the stainless steel band is the b surface, and the other surface is the a surface. <Preparation of transparent resin film 2> (Dope composition (II)) Cellulose triacetate (acetyl substitution degree 2.7) 100 parts by mass Ethylphthalylethyl glycolate 6 parts by mass Tinuvin 171 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 2 Parts by mass Silicon oxide fine particles (Aerosil 200V) 0.1 parts by mass Methylene chloride 430 parts by mass Methanol 90 parts by mass The above composition was placed in a closed container and completely dissolved with stirring while maintaining the temperature at 80 ° C.

The dope is then filtered, cooled to 33 ° C.
The solution was uniformly cast on a stainless steel band, and the solvent was evaporated until peeling became possible. After peeling from the stainless band, it was dried while holding the width with a tenter and 1.05 times in the width direction. The film is stretched so that the film thickness is 50
A transparent resin film 2 having a thickness of μm was obtained.

The surface in contact with the stainless steel band is the b surface, and the other surface is the a surface. <Production of transparent resin film 3> (Dope composition (c)) Cellulose acetate propionate 100 parts by mass (acetyl substitution degree 2.0, propionyl substitution degree 0.8) Ethylphthalylethyl glycolate 2 parts by mass Triphenyl Phosphate 8 parts by mass Tinuvin 171 (manufactured by Ciba Specialty Chemicals Co., Ltd.) 2 parts by mass Silicon oxide fine particles (Aerosil 200V) 0.2 parts by mass Methylene chloride 430 parts by mass Methanol 90 parts by mass The above composition is charged into a closed container and added. The solution was kept at 80 ° C. under pressure and completely dissolved with stirring.

The dope is then filtered, cooled and cooled to 33 ° C.
The solution was uniformly cast on a stainless steel band, and the solvent was evaporated until peeling became possible. After peeling from the stainless band, it was dried while holding the width with a tenter and 1.05 times in the width direction. The film is stretched so that the film thickness is 4
A 0 μm transparent resin film 3 was obtained.

The surface in contact with the stainless steel band is the b surface, and the other surface is the a surface. <Transparent resin film 4> KONICAC KC4UX2M
W (film thickness 40 μm, triacetyl cellulose film,
Konica Corp. was used as the transparent resin film 4.

The following compositions were prepared. <Clear hard coat layer (CHC layer) coating composition> Dipentaerythritol hexaacrylate monomer 60 parts by mass Dipentaerythritol hexaacrylate dimer 20 parts by mass Dipentaerythritol hexaacrylate trimer or more components 20 parts by mass Di Ethoxybenzophenone UV initiator 2 parts by mass Isopropyl alcohol 50 parts by mass Ethyl acetate 50 parts by mass Methyl ethyl ketone 50 parts by mass << Preparation of film having clear hard coat layer (CHC layer) >> One side of the transparent resin film 1 prepared by the above method ( The surface (b side) is extrusion-coated to a wet film thickness of 13 μm using the coating and drying and ultraviolet irradiation equipment shown in FIGS. 1, 6, 7 and 10 on the surface b) and then to 80 ° C. 120mJ after drying in the set drying unit / Cm ² at ultraviolet irradiation, dry film thickness 4
An optical film 1 of the present invention shown in Table 1 is provided with a clear hard coat layer having a center line average surface roughness Ra of 15 nm and a center line average surface roughness Ra of 15 nm.
.About.3 and comparative optical film 4 were obtained.

According to the image clarity measuring method defined in JIS H8686, the image clarity was evaluated from the waveform of the light quantity obtained through an optical comb of 2.0 mm.

Image clarity Image clarity ⊚: 95% or more ∘: 90 to less than 95% Δ: 80 to less than 90% ×: less than 80% The results are shown in Table 1. Incidentally, FIG. 10 is a schematic view of a conventional coating and drying apparatus.

[0138]

[Table 1]

It was confirmed that the optical films 1 to 3 of the present invention had high image definition and excellent flatness, but the comparative optical film 4 had low image definition and poor flatness. . Even by visual evaluation, the optical film 1 of the present invention
In Nos. 3 to 3, the reflected light of the fluorescent lamp was almost linear, whereas in the comparative optical film 4, fluctuations were recognized at an amplitude greater than the thickness of the fluorescent lamp.

Example 2 The following coating composition was prepared. Other than these, Example 1
Using the transparent resin film and the clear hard coat layer coating composition prepared in (1), the coating / drying apparatus shown in FIGS. 5-18 were produced.

<Antiglare Layer (AG Layer) Coating Composition> Dipentaerythritol Hexaacrylate Monomer 60 parts by mass Dipentaerythritol Hexaacrylate Dimer 20 parts by mass Dipentaerythritol Hexaacrylate Trimer 20 parts by mass or more Part Diethoxybenzophenone UV initiator 2 parts by mass Silicon oxide fine particles Aerosil R972V 5 parts by mass Isopropyl alcohol 50 parts by mass Ethyl acetate 50 parts by mass Methyl ethyl ketone 50 parts by mass <Backcoat layer (BC layer) coating composition> Acetone 72 parts by mass Methanol 18 Parts by mass propylene glycol monomethyl ether 10 parts by mass diacetyl cellulose 0.5 parts by mass 2% acetone dispersed ultrafine particle silica (Aerosil 200 V manufactured by Nippon Aerosil Co., Ltd.) 0.1 parts by mass <medium refractive index layer (M layer) Composition> Tetra (n) butoxytitanium 250 parts by weight Terminal reactive dimethyl silicone oil (N-Unicar L-9000) 0.48 parts by weight Aminopropyltrimethoxysilane (Shin-Etsu Chemical KBE903) 22 parts by weight UV curable Epoxy resin (KR500 manufactured by Asahi Denka Co., Ltd.) 21 parts by mass Propylene glycol monomethyl ether 870 parts by mass Isopropyl alcohol 8000 parts by mass Methyl ethyl ketone 870 parts by mass <High refractive index layer (H layer) composition> Tetra (n) butoxy titanium 310 parts by mass Terminal 3. Reactive dimethyl silicone oil (L-9000 manufactured by Nippon Unicar) 0.4 parts by mass Aminopropyltrimethoxysilane (KBE903 manufactured by Shin-Etsu Chemical Co., Ltd.) 4.8 parts by mass UV curable epoxy resin (KR500 manufactured by Asahi Denka Co., Ltd.) 4. 6 parts by mass polypropylene Glycol monomethyl ether 1350 parts by mass Isopropyl alcohol 7000 parts by mass Methyl ethyl ketone 1350 parts by mass <Low refractive index layer (L layer) composition> Tetraethoxysilane hydrolyzate A 1020 parts by mass Terminal reactive dimethyl silicone oil (L-manufactured by Nippon Unicar Co., Ltd.) 9000) 0.42 parts by mass Propylene glycol monomethyl ether 2500 parts by mass Isopropyl alcohol 6500 parts by mass <Preparation of tetraethoxysilane hydrolyzate A> 300 g of tetraethoxysilane and 455 g of ethanol are mixed,
After adding 295 g of 0.3% citric acid thereto, a hydrolyzate of tetraethoxysilane was obtained by stirring at room temperature for 1 hour.

<< Preparation of Film Having Backcoat Layer (BC Layer) >> The transparent resin films 1 to 4 were coated with the BC layer coating composition so as to have a wet film thickness of 13 μm, and the temperature was raised to 80 ° C. A BC layer was provided by drying in a set drying unit.

<< Preparation of Film Having Clear Hard Coat Layer (CHC Layer) >> A transparent hard resin film having a BC layer prepared by the above-mentioned method was coated with a clear hard coat layer coating composition on one side (b side) in a wet film thickness. It is extrusion coated to 13 μm, dried in a drying unit set at 80 ° C., and then irradiated with ultraviolet rays at 120 mJ / cm ² , and the dry film thickness is 4 μm and the center line average surface roughness Ra is 15 nm of clear hard. A coat layer was provided.

<< Preparation of Film Having Antiglare Layer (AG Layer) >> One side (b) of the transparent resin film having the BC layer described above.
Surface) is coated with an antiglare layer coating composition by extrusion so as to have a wet film thickness of 12 μm, then dried in a drying section set at 85 ° C., and then irradiated with ultraviolet rays at 120 mJ / cm ² to give a dry film thickness. The center line average surface roughness Ra is 0.4 μm at 4 μm.
A 2 μm antiglare layer was provided.

<< Production of Film Having Medium Refractive Index Layer (M Layer) >> The medium refractive index layer composition was applied onto the clear hard coat layer or the antiglare layer with an extrusion coater to prepare 1
After drying at 00 ° C for 1 minute, a high pressure mercury lamp (80
Ultraviolet light was applied at 175 mJ / cm ² for curing using W) to form a medium refractive index layer having a thickness of 78 nm and a refractive index of 1.70 on the clear hard coat layer or the antiglare layer.

<Production of Film Having High Refractive Index Layer (H Layer)> The above high refractive index layer composition was applied onto the above-mentioned medium refractive index layer by an extrusion coater and dried at 100 ° C. for 1 minute. , Using a high pressure mercury lamp (80W),
It was irradiated with 5 mJ / cm ² and cured to prepare a high refractive index layer film-1. The thickness of the high refractive index layer is 66 nm.
The refractive index was 1.85.

<< Preparation of Film Having Low Refractive Index Layer (L Layer) >> The above low refractive index layer composition was applied onto the above high refractive index layer with an extrusion coater and dried at 80 ° C. for 5 minutes. After that, it was further heat-cured at 120 ° C. for 5 minutes to prepare an optical film. The low refractive index layer had a thickness of 95 nm and a refractive index of 1.45.

Table 2 shows the layer structure of the obtained optical films 5 to 18 and the coating / drying apparatus used. For each optical film, the unevenness of the tint of the reflected light was visually evaluated.
The results are shown in Table 2.

[0149]

[Table 2]

The optical films 5 to 14 of the present invention showed almost uniform color of reflected light in purple, but the comparative optical films 15 to 18 had at least three different colors of reddish purple, purple and bluish purple. It had a mottled pattern. Also, in the visual evaluation, in the optical films 5 to 14 of the present invention, the reflected light of the fluorescent lamp looked like a rod-shaped fluorescent tube in a substantially straight line, whereas in the optical films 15 to 18 of the comparison, the thickness was larger than that of the fluorescent lamp. A fluctuation was recognized at the amplitude of. From this, it was confirmed that an optical film having extremely excellent flatness can be obtained by the method for producing an optical film of the present invention.

Example 3 <Evaluation as Polarizing Plate> Using the optical films 1 to 18 produced in Examples 1 and 2 as protective films for polarizing plates, polarizing plates were prepared according to the following method. A polyvinyl alcohol film with a thickness of 120 μm was used for iodine 1
Part, potassium iodide 2 parts, and boric acid 4 parts were dipped in an aqueous solution and stretched 4 times at 50 ° C. to obtain a polarizing film.

The following 1. ~ 5. In the step, a polarizing plate was produced by laminating the polarizing film and the polarizing plate protective film.

<Production Method of Polarizing Plate> 1. 1. Two protective film samples cut into a length direction of 30 cm and a width direction of 18 cm were immersed in a 2M sodium hydroxide solution at 60 ° C. for 2 minutes, further washed with water, and dried. 2. The above polarizing film having the same size as the protective film sample is immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds. The above 2. Lightly remove the excess adhesive adhering to the polarizing film of 1. Place it on the b-side of the protective film sample of 1. 3. Laminate and arrange so that the b side of the same sample film and the adhesive are in contact with each other. With a hand roller, the above 3. Excess adhesive and air bubbles are removed from the ends of the laminate of the polarizing film and the protective film, which have been laminated in step 1, and the layers are bonded together. Hand roller is about 19-29N
/ Cm ² stress, roller speed is about 2m / m
4. In a dryer at 5.80 ° C. The sample obtained in 1. was left for 2 minutes.

Regarding the polarizing plate prepared in this way,
When the reflected light was visually confirmed, the polarizing plates using the optical films 1 to 3 and 5 to 14 of the present invention were reflected images with very little distortion, whereas the comparative optical films 4 and 15 to 18 were used. Distortion of the reflected image was observed in the polarizing plate using. As a result of using these polarizing plates on the front surface of a liquid crystal display, the visibility of a liquid crystal display using polarizing plates made using the optical films 1 to 3 and 5 to 14 of the present invention is better than that of a comparative one. It was good.

Example 4 Using the gravure coating apparatus shown in FIG. 9, (a) in FIG.
The clear hard coat layer coating composition was applied using a gravure roll having the gravure pattern shown in (b), (c) and (d), and the number of bubbles in the coating film was counted. As a result, (a) was 8 / 20m, while
The patterns using the patterns (b), (c), and (d) were all 0/20 m.

Example 5 The optical film 12 of Example 2 and the optical film 12 of Example 2 were used except that the gravure coating apparatus shown in FIG. 9 was used without using an extrusion coater and the gravure roll having the gravure pattern shown in FIG. 8B was used. Each layer was applied and dried so as to have the same structure as in No. 13 (transparent resin film, layer structure and drying device).

The unevenness of reflected light on the surface of the obtained resin film was evaluated. As a result, no unevenness was visually observed.

[0158]

According to the present invention, an optical film having excellent flatness can be easily obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of a drying device using a drum-shaped rotating support used in the present invention.

FIG. 2 is a perspective view of the drying device of FIG.

FIG. 3 is a perspective view of a drying device using a support body in which two drums used in the present invention are connected by a belt and rotated.

FIG. 4 is a schematic view of a drying device for drying while gripping the width with a tenter used in the present invention.

FIG. 5 is a diagram showing a specific example of a tenter.

FIG. 6 is a perspective view of a drying device using a drum-shaped rotating support body while holding a width by a tenter used in the present invention.

FIG. 7 is a schematic view of a drying device using a support body in which two drums are connected by a belt and rotated while gripping a width by a tenter used in the present invention.

FIG. 8 is a roll bottom view showing an example of a diagonal gravure pattern applied to a gravure roll.

FIG. 9 shows a schematic cross-sectional view of a gravure coating apparatus used in the coating method of the present invention.

FIG. 10 is a schematic view of a conventional coating and drying apparatus.

[Explanation of symbols]

1 resin film 2 drums 3 die coater 4 Actinic ray irradiation device 5 Guide roller 6 drying zone D drum diameter L resin film width 21,22 drums 23 belt 41 tenter 51 clip tenter 52 shoe 53 Fixed base 54 pin tenter 55 pin 56 fixed stand

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29C 71/00 B29C 71/00 C08J 7/02 CEP C08J 7/02 CEPZ G02B 1/10 G02B 5/30 1 / 11 C08L 1:10 5/30 G02B 1/10 A // C08L 1:10 ZF term (reference) 2H049 BA02 BA27 BB13 BB33 BB43 BC01 BC14 2K009 AA05 AA06 AA15 BB28 CC03 CC09 DD02 EE00 4D075 AC04 AC14 AC25 DA044646 BB46Y DB33 DC24 EA45 EB35 EC35 4F073 AA10 AA14 AA21 AA24 AA28 BA03 BB01 CA45 EA13 EA65 4F201 AA01 AA21 AG01 AG03 AH73 BA07 BC01 BC02 BC12 BC33 BC37 BR02 BR17 BR33 BR34 BR37

Claims (31)

[Claims] 1. A method for producing an optical film, which comprises applying a coating solution onto a resin film that is continuously conveyed, and drying it while winding it on a rotary support having a diameter equal to or larger than the width of the resin film. . 2. A method for producing an optical film, which comprises applying a coating liquid on a resin film that is continuously conveyed and drying the resin film while gripping the width. 3. An optical film, characterized in that a coating liquid is applied onto a resin film which is continuously conveyed, and the resin film is wound on a rotary support having a diameter equal to or larger than the width of the resin film and dried while gripping the width. Manufacturing method. 4. The method for producing an optical film according to claim 1, wherein the coating liquid contains an organic solvent that dissolves or swells the resin film. 5. The tension applied in the width direction is less than the transport tension of 0.
It is 5 times to 1.5 times, or 1 or 2 characterized by the above-mentioned.
A method for producing the optical film described above. 6. A coating solution containing an actinic ray-curing substance is applied onto a resin film which is continuously conveyed, and the actinic ray is irradiated while being wound on a rotary support having a diameter equal to or larger than the width of the resin film. A method for producing an optical film having a characteristic actinic ray-curable layer. 7. A method for producing an optical film having an actinic ray-curable layer, which comprises applying a coating solution containing an actinic ray-curing substance onto a resin film that is continuously conveyed and irradiating the actinic ray while gripping the width. . 8. A coating solution containing an actinic ray-curing substance is applied onto a resin film that is continuously conveyed, and the actinic ray is irradiated while being wound on a rotary support having a diameter equal to or larger than the width of the resin film and gripping the width. A method for producing an optical film having an actinic radiation-curable layer, comprising: 9. An optical film produced by the method according to claim 1. 10. An optical film, wherein an actinic radiation curable layer is produced by the method according to any one of claims 6 to 8. 11. The optical film according to claim 10, wherein the actinic radiation curable layer is a hard coat layer. 12. The optical film according to claim 10, wherein the actinic radiation curable layer is an optical interference layer. 13. The optical film according to claim 10, wherein the resin film is a cellulose ester film. 14. The optical film according to claim 10, wherein the resin film has a film thickness of 10 to 60 μm. 15. A polarizing plate having the optical film according to any one of claims 10 to 14 on at least one surface thereof. 16. A display device using the optical film according to any one of claims 10 to 14. 17. The coating method used in the method for producing an optical film according to claim 1, wherein a running direction and an axial direction of the film are provided below a continuously conveyed belt-shaped resin film. A gravure roll, which is arranged so as to be orthogonal to each other and has a gravure pattern formed on the entire outer peripheral surface of a metal or ceramic material having a diameter of 20 mm to 50 mm, is rotated at a peripheral speed having a relative speed to the resin film. With it, wiped before applying the excess coating liquid by the doctor blade from the surface of this gravure roll, a fixed amount of the coating liquid is applied to the lower surface of the film at a position where the upper surface of the resin film is in a free state, A gravure coating method for uniformly applying a coating liquid to the resin film, before and after the resin film contacts the gravure roll. A coating method comprising means for preventing deformation of the film across the width. 18. The coating method according to claim 17, wherein an expander roll is arranged before or after the resin film is in contact with the gravure roll as a means for ensuring the flatness. 19. The position of the roll for pressing the film against the gravure roll is set to 2 with respect to the contact position of the gravure roll.
20 mm or less, characterized in that
The coating method described. 20. The coating method according to claim 17, wherein a thin film having a dry film thickness of less than 0.2 μm is formed on the resin film directly or through another layer. 21. The gravure pattern is a diagonal line, and the opposite gravure pattern is arranged at the end on the side which becomes the tip of the gravure pattern and is applied.
21. The coating method according to any one of 20 to 20. 22. The openings of the end gravure pattern are larger than the openings of the main coating area.
22. The coating method according to any one of 21. 23. The ring-shaped groove is provided at an end of the gravure pattern, according to any one of claims 17 to 22.
The application method described in the item. 24. An optical film coated by the coating method according to any one of claims 17 to 23. 25. An optical film, characterized in that an actinic radiation curable layer is coated by the coating method according to any one of claims 17 to 23. 26. The optical film as claimed in claim 25, wherein the actinic radiation curable layer is a hard coat layer. 27. The optical film as claimed in claim 25, wherein the actinic radiation curable layer is an optical interference layer. 28. The optical film according to claim 25, wherein the resin film is a cellulose ester film. 29. The optical film according to claim 25, wherein the resin film has a film thickness of 10 to 60 μm. 30. A polarizing plate having the optical film according to any one of claims 25 to 29 on at least one surface thereof. 31. A display device using the optical film according to any one of claims 25 to 29.