JP5915536B2 - Manufacturing method of optical film roll - Google Patents

Description

  The present invention relates to an optical film and a method for producing the same.

  With the recent increase in area of displays, optical films that are mass-produced are desired to be wide and long. The optical film is wound up after production to form a film roll. Due to the widening and lengthening of the optical film, there has been a problem of blocking during storage and transportation of the film roll. Specifically, sticking failure where the films are stuck to each other and the film is deformed, or convex failure where the foreign matter is sandwiched between the films, resulting in a convex deformation. Sticking failures often occur at the center in the width direction, and convex failures often occur at both ends in the width direction. When such blocking occurred, the failed part remained as an indentation during use, and thus could not be used as an optical film. In particular, when the film width is increased to 1.3 m or more, the effect of the knurling provided on both sides is reduced, and the sticking failure particularly occurs in the central portion.

  In the roll film, an air layer is formed between the films by knurling on both sides, preventing contact between the films and blocking. However, the air layer becomes narrow and the films come into contact with each other due to expansion, contraction, and aging of the film due to temperature and humidity changes during storage and transportation. At this time, if the friction coefficient of the front and back surfaces of the film is large, stress concentrates on the contact portion, and blocking such as sticking or convex failure occurs. Therefore, in order to prevent blocking, it is necessary to reduce the friction coefficient of the film front and back surfaces.

  In order to reduce the coefficient of friction, a technique is known in which fine particles are contained as a mat material to form irregularities on the film surface (Patent Document 1). However, even if a mat material having a large particle diameter or a small particle diameter is used, the haze of the optical film is increased, resulting in a new problem that the image quality of the display is impaired.

  Therefore, a technique for controlling the surface roughness Ra of the optical film within a predetermined range with a surface shape transfer roll is disclosed (Patent Document 2). However, even such a technique cannot sufficiently prevent blocking.

JP 2004-42653 A JP 2006-240228 A

  An object of this invention is to provide the optical film which can fully prevent blocking, while having a comparatively small haze, and its manufacturing method.

The present invention includes an unevenness forming step of forming an unevenness by a mold roll on the surface of a polymer film containing a resin and having a fine particle content of 0.2% by weight or less with respect to the resin component;
A winding step of winding the optical film on which the irregularities are formed by the irregularity forming step in a multilayer shape around the core, and a method for producing an optical film roll,
The unevenness average distance Sm (mm) of one surface of the optical film on which the unevenness is formed by the mold roll in the unevenness forming step is 1 × 10 ^{−3 to} 12 × 10 ⁻³ , and the one surface is Formula (1):
Ra ≧ 3.125 × P × Sm ³ / (E × I) (1)
[In formula (1), Ra is the center line average roughness (mm) of the film surface;
P is a load (N) applied between adjacent convex portions of the film surface due to the tension at the time of winding the film, and the formula (2):
P = (F / x) × Sm (2)
(In formula (2), x is the film width (mm) at the time of winding the film; F is the film tension (N) at the time of winding the film); Sm is the unevenness of the film surface Average distance (mm);
E is the elastic modulus (MPa) of the film;
I is the formula (3):
I = (Sm × t ³ ) × 10 ⁻³ / 12 (3)
(In the formula (3), t is the thickness of the film (mm) is a) a method of manufacturing an optical film roll and satisfies the second moment of the film represented by (mm ⁴⁾ is.

  The optical film of the present invention can sufficiently prevent blocking during storage and transportation of the film roll while having a relatively small haze by having the above configuration.

It is a schematic diagram for demonstrating the formula prescribed | regulated by this invention. It is a schematic diagram for demonstrating the calculation formula when calculating | requiring deflection amount (delta) 'in the beam structure of a member in structural mechanics. It is a schematic block diagram of the manufacturing apparatus for demonstrating an example of the method of manufacturing the optical film which concerns on this invention by the solution casting method. It is a schematic block diagram of the manufacturing apparatus for demonstrating an example of the method of manufacturing the optical film which concerns on this invention by a melt casting method.

(Optical film)
In the optical film of the present invention, the center line average roughness Ra and the uneven average interval Sm (mm) of the surface of one surface are represented by the formula (1);
Ra ≧ 3.125 × P × Sm ³ / (E × I) (1)
It is a resin film satisfying The form of the optical film of the present invention is not particularly limited. For example, the optical film may have a form of a film roll in which the optical film is wound in a multilayer around the core, or the optical film You may have the form of the film sheet as mounting components, such as a liquid crystal display device wound out from the film roll and cut | judged to the predetermined dimension according to a use.

  In formula (1), Ra is the center line average roughness (mm) of the film surface. Ra uses an average value of values measured at arbitrary 10 points by New View 5010 (manufactured by ZYGO). Ra is expressed in the unit of “mm” in the formula (1), and is usually 0.4 to 70 nm, preferably 0.5 to 50 nm when converted to the unit of “nm”. Ra on the one surface of the optical film can be controlled by Ra on the surface of the mold roll described later and / or a transfer rate by the mold roll. For example, when Ra on the mold roll surface is increased and / or the transfer rate is increased, Ra on the one surface increases. When Ra on the surface of the mold roll is reduced and / or the transfer rate is reduced, Ra on the one surface is reduced. The transfer rate by the mold roll can be adjusted by the film transport tension, the contact time with the mold roll, and the like.

  In formula (1), Sm is the average unevenness (mm) on the film surface. For Sm, an average value of values measured at arbitrary 10 points by New View 5010 (manufactured by ZYGO) is used. Sm is expressed in units of “mm” in the formula (1), and is usually 1 to 12 μm, preferably 1 to 5 μm when converted to “μm” units. Sm on the one surface of the optical film can be controlled by adjusting Sm on the mold roll surface described later. For example, when Sm on the mold roll surface is increased, Sm on the one surface is increased. When Sm on the mold roll surface is reduced, Sm on the one surface is reduced.

In formula (1), P is a load (N) applied between adjacent convex portions on the film surface at the time of winding the film, and formula (2);
P = (F / x) × Sm (2)
It is a value represented by In this specification, the time of film winding means the time when the film is finally wound in a multilayered form around the core in the continuous manufacturing process of the optical film, and the film roll is manufactured by winding. . At the time of film winding, the film is usually wound at a length of 200 to 10000 m, preferably 2000 to 9000 m in the length in the film conveyance direction. As the film length is longer, blocking is more likely to occur, but in the present invention, blocking can be effectively prevented even with a relatively long film length as described above.

  In formula (2), x is a film width (mm) at the time of film winding. The film width is the length in the width direction of the film. The width direction is a direction parallel to the axial direction of the core used at the time of winding, in other words, a direction perpendicular to the film transport direction in the continuous production of the film. . As the film width x is larger, blocking is more prominent. However, in the present invention, blocking can be effectively and sufficiently prevented even if the film width is large. x is preferably 1300 to 4000 mm, more preferably 1400 to 2200 mm.

  In Formula (2), F is the film tension (N) at the time of film winding. The film tension is the maximum tension applied to the film during winding. The film tension is usually gradually reduced from the initial stage to the final stage at the time of winding. In this case, F is the initial film tension (N) at the time of winding the film, and usually 40 to 600 N per 1000 mm width, Preferably it is 60-300N.

  In the formula (2), Sm is the average irregularity interval (mm) on the film surface as described above.

  In formula (1), E is the elastic modulus (MPa) of the film. E is determined by the resin constituting the film. For example, E when the resin is a cellulose resin is about 3000 MPa. For example, when the resin is a (meth) acrylic resin, E is about 3100 MPa. For example, when the resin is composed of 50% by weight of a cellulose-based resin and 50% by weight of a (meth) acrylic resin, E is about 3050 MPa. For example, when the resin is a cycloolefin resin, E is about 2400 MPa.

I is the cross-sectional second moment (mm ⁴ ) of the film and is given by formula (3);
I = (Sm × t ³ ) × 10 ⁻³ / 12 (3)
It is a value represented by

  In formula (3), Sm is the same as defined in formula (1).

  In formula (3), t is the film thickness in the unit of “mm”, and when expressed in the unit of “μm”, it is usually 10 to 100 μm, preferably 20 to 80 μm.

Formula (1) is the amount of film deflection δ (nm) expressed by formula (x1);
δ = P × Sm ³ / (48 × E × I) (x1)
[In the formula (x1), P, Sm, E and I are the same as those in the formula (1)] means that Ra ≧ 150 × δ. That is, when the film is wound with tension and has the form of a film roll, as shown in FIG. 1, the adjacent convex portions on the surface of the film are bent due to the tension. It means that a value 150 times the deflection amount δ of this film is equal to or less than the center line average roughness Ra. When the value of 150 × δ is equal to or less than Ra, the contact between the film f1 bent by the load P and the film f2 immediately below is sufficiently prevented, so that blocking is sufficiently prevented. If the value of 150 × δ is larger than Ra, even if the film f1 bent by the load P is not in contact with the film f2 immediately below, the film shrinks during storage and transportation and air between the films escapes. Therefore, blocking cannot be sufficiently prevented.

As shown in FIG. 2, the equation (x1) is an equation (y1) for obtaining the deflection amount δ ′ of the beam structure of the member in structural mechanics;
δ ′ = (P ′ × L ³ ) / (48 × E ′ × I ′) (y1)
[In formula (y1), δ ′ is the deflection amount (mm) of the beam; P ′ is the load (N) applied to the beam; L is the distance (mm) between the columns supporting the beam; E ′ is a flexural modulus of the material constituting the beam (MPa); I 'is the second moment of the beam member (mm4), I' is expressed by = b't ^'3/12. b ′ is the width (mm) of the beam, and t ′ is the thickness (mm) of the beam].

In the present embodiment, the formula (1) is preferably the formula (z1) from the viewpoint of preventing blocking;
1.0 ≦ Ra-3.125 × P × Sm ³ /(E×I)≦25.0 (z1)
And more preferably the formula (z2);
1.2 ≦ Ra−3.125 × P × Sm ³ /(E×I)≦5.0 (z2)
It is.

  In the optical film of the present invention, minute irregularities are formed over substantially the entire one surface. The dimensions of the irregularities may be dimensions that allow Ra and Sm to be within a predetermined range (a range that satisfies the above formula (1)). The shape of the unevenness is not particularly limited, and, for example, streaky unevenness in which ridges connected in various directions such as the width direction, the conveyance direction orthogonal to the width direction, or the oblique direction are repeatedly formed in parallel with each other. Alternatively, it may be a point-like unevenness in which cone-shaped convex portions are formed regularly or irregularly. In general, the cross-sectional shapes of the convex portions and the concave portions in such irregularities are each independently a substantially triangular shape or a substantially semicircular shape. The said cross-sectional shape should just have in the vertical cross section with respect to the width direction or the vertical cross section with respect to a film conveyance direction.

  The other surface of the optical film of the present invention is not particularly limited as long as the center line average roughness Ra and the unevenness average interval Sm of the surface of the one surface satisfy the above formula, but may be smooth. preferable. Specifically, the center line average roughness Ra of the other surface is preferably smaller than Ra of the one surface, and is usually 5 nm or less, particularly 0.01 to 3 nm. Moreover, the uneven | corrugated average space | interval Sm of the said other surface is 1-5 micrometers, Especially 1.5-5 micrometers is preferable. For Ra and Sm on the other surface of the optical film, no roller is brought into contact with the other surface in the concave / convex forming step, which will be described later, or a back roll installed opposite to the mold roll in the concave / convex forming step is used. Is achieved by adjusting Ra and Sm on the surface of the back roll.

  The optical film of the present invention may have any form. For example, the optical film may have a form of a film roll in which the optical film is wound in a multilayer around the core, or the You may have the form of the film sheet as mounting components, such as a liquid crystal display device wound out from the optical film roll, and cut | judged to the predetermined dimension according to a use.

  When the optical film of the present invention has the form of a film sheet, one surface may satisfy the above formula over the entire surface, and preferably the other surface may be smooth as described above.

  When the optical film of the present invention has the form of a film roll, one surface satisfies the above formula over the entire surface, and preferably the other surface is smooth as described above. When the optical film roll of the present invention has a knurling portion particularly at both ends in the width direction of the film, the region inside the knurling portion on the one surface satisfies the above formula over the entire region, preferably knurling on the other surface. The region inside the portion may be smooth as described above.

  In the optical film of the present invention, as long as one surface satisfies the above formula, Ra of the one surface may be substantially uniform in the width direction, or decreases from the center to both ends in the width direction. Or it may have an increasing slope. In the case where Ra has a slope that decreases or increases from the central portion toward both ends in the width direction, the above-described expression may be satisfied at least in each of the central portion and both end portions.

  In this specification, Ra being substantially uniform in the width direction means that when Ra is measured at any 10 points in the width direction, the difference between the maximum value and the minimum value is less than 1.0 nm. , Preferably 0.5 nm or less.

  Ra has a gradient that decreases or increases from the central portion toward both ends in the width direction, and has a relationship in which Ra at the central portion is larger than both end portions or Ra at both end portions is larger than the central portion. In this case, the Ra at the intermediate portion between the central portion and each end portion may be a value between the Ra at the central portion and the Ra at the end portion. If Ra at the center is larger than both ends, sticking failure that often occurs in the center can be more effectively prevented. If Ra at both ends is larger than that at the center, it is possible to more effectively prevent convex failures that often occur at both ends. The change in the width direction of Ra may be continuous or stepwise, but is preferably continuous from the viewpoint of appearance such as film unevenness and haze.

  For example, when Ra at the center is larger than both ends, the rate of change of Ra from the center in the width direction to both ends is preferably -2.5 to -40% from the viewpoint of preventing sticking failure. .

The rate of change means that the center line surface roughness at the center is Rac (mm) and the center line surface roughness at the end is Rae (mm).
Rate of change Cr (%) = {(Rae−Rac) / Rac} × 100
The surface roughness gradient represented by The rate of change Cr ₁ from the center to one end and the rate of change Cr ₂ from the center to the other end may be independently within the above range. Preferably, the absolute value of the difference between Cr ₁ and Cr ₂ is 1% or less, more preferably 0.5% or less.

  In the present specification, the central portion in the width direction means a region within the range of 50 mm from the center (line) in the width direction of the film (a central region having a length in the width direction of 100 mm). To do. The average value of Ra measured at arbitrary 10 points in the region is used as the central portion of Rac.

  The end portion in the width direction means a region having a distance of 100 mm from the film end surface in the width direction of the film. In particular, when the optical film of the present invention has a knurling portion at both ends in the film width direction, the end portion means a region having a distance of 100 mm from the center side boundary line of the knurling portion to the center side. Shall. As the Rae at the end, an average value of Ra measured at arbitrary 10 points in the region is used.

Also, for example, when Ra at both ends is larger than the center, the rate of change of Ra from the center in the width direction to both ends is preferably 2.5 to 75% from the viewpoint of preventing convex failure. . The change rate is represented by the same change rate as described above. The rate of change Cr ₁ from the center to one end and the rate of change Cr ₂ from the center to the other end may be independently within the above range, but preferably the difference between Cr ₁ and Cr ₂ The absolute value is 1% or less, more preferably 0.5% or less.

  The optical film of the present invention contains at least a resin, and may further contain additives such as a plasticizer, an ultraviolet absorber, an antioxidant, a matting agent, and a retardation increasing agent. In the present invention, in particular, the content of the matting agent is 0.2% by weight or less, preferably 0.1% by weight or less, and most preferably 0% by weight with respect to the resin component constituting the optical film. This is because when the content of the matting agent is too large, the haze of the film increases. In the present invention, blocking can be effectively prevented even if the matting agent content is small as described above.

  Fine particles are used as the matting agent. The fine particles refer to fine particles having an average particle diameter of less than 1 μm, particularly 5 nm or more and less than 1 μm, present in the film or on the surface thereof. The fine particles may be present as primary particles in the film, or may be present by aggregating a plurality of particles to form secondary particles (secondary aggregates). The refractive index of the fine particles is preferably close to the refractive index of the resin component used in the film with little increase in haze. Since the refractive index of the cellulose ester film is about 1.47 to 1.49, the refractive index of the fine particles is preferably 1.46 to 1.50, more preferably 1.47 to 1.49.

  The average particle size of the fine particles is determined by measuring the particle size of the primary particles when the fine particles are present as primary particles, and measuring the particle size of the secondary particles when the fine particles are present as secondary particles. It is a value obtained by averaging. Such an average particle diameter is obtained from, for example, the particle diameter of 100 arbitrary particles by observing fine particles with an electron microscope. Here, each particle size is expressed by a diameter assuming a circle equal to the projected area. Alternatively, it can be obtained by diluting fine particles in a solvent and measuring using a dynamic light scattering method particle size measuring apparatus Zeta Sizer 1000HS (manufactured by Malvern).

The kind of fine particles may be an inorganic compound or an organic compound. Examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, tin oxide and the like. In this, it is preferable that it is a compound containing a silicon atom, and especially silicon dioxide is preferable. As silicon dioxide fine particles, for example, Aerosil manufactured by Aerosil Co., Ltd.
200, 200V, 300, R972, R972V, R974, R202, R812, R805, OX50, TT600 and the like. Examples of the organic compound include acrylic resin, silicone resin, fluorine compound resin, and urethane resin.

  The matting agent may be elastic fine particles. The elastic fine particles are polymer fine particles having a core-shell structure, and are fine particles having a hard shell layer containing a methyl methacrylate polymer on the surface of rubber-like polymer fine particles (core (core) portion). The rubbery polymer constituting the core of the elastic fine particles is preferably an alkyl acrylate rubber. As a manufacturing method of the core part, a method of forming by seed emulsion polymerization is known. The methyl methacrylate polymer constituting the shell layer is meant to include a homopolymer of methyl methacrylate and a copolymer of the methyl methacrylate and a monomer copolymerizable therewith. The shell layer can be produced by emulsion polymerization of a predetermined monomer in the presence of the core latex.

  As the resin component constituting the optical film of the present invention, a known polymer conventionally used in the field of optical film can be used. Specifically, cellulose resin, (meth) acrylic resin, cycloolefin resin and A mixture thereof may be mentioned. Preferably, a cellulose resin, a (meth) acrylic resin, a cycloolefin resin, or a mixture thereof is contained.

  The cellulose resin is preferably a lower fatty acid ester of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. Specific examples of the cellulose resin include, for example, cellulose acetate, cellulose propionate, cellulose butyrate and the like, and JP-A Nos. 10-45804, 08-231761, U.S. Pat. No. 2,319,052, and the like. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate can be used. Among the above descriptions, the lower fatty acid esters of cellulose particularly preferably used are cellulose triacetate and cellulose acetate propionate. These cellulose esters can be used alone or in combination.

  The cellulose resin is preferably a cellulose resin that simultaneously satisfies the following formulas (I) and (II) when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group or butyryl group is Y.

Formula (I) 2.6 ≦ X + Y ≦ 3.0
Formula (II) 0 ≦ X ≦ 2.5

  Among them, it is preferable that 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9. The portion that is not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods. The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  The number average molecular weight (Mn) of the cellulose resin is preferably 60000-300000, and more preferably 70000-200000. The cellulose resin used in the present invention preferably has a weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of 4.0 or less, more preferably 1.4 to 2.3.

  In this specification, since the average molecular weight and molecular weight distribution of the resin can be measured using high performance liquid chromatography, the number average molecular weight (Mn) and the weight average molecular weight (Mw) are calculated using this, and the ratio is calculated. be able to.

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK
Standard polystyrene (manufactured by Tosoh Corp.) Mw = 1,000,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

  As the cellulose resin, cellulose esters synthesized using cotton linter, wood pulp, kenaf and the like as raw materials can be used alone or in combination. In particular, it is preferable to use a cellulose ester synthesized from cotton linter (hereinafter sometimes simply referred to as linter) alone or in combination.

  The (meth) acrylic resin includes an acrylic resin and a methacrylic resin. Although it does not restrict | limit especially as a (meth) acrylic resin, What consists of 50-99 mass% of methyl methacrylate units and 1-50 mass% of other monomer units copolymerizable with this is preferable.

  Examples of other monomers copolymerizable with methyl methacrylate include alkyl methacrylates having 2 to 18 alkyl carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, α, such as acrylic acid and methacrylic acid, β-unsaturated acids, maleic acids, fumaric acids, dicarboxylic acids containing unsaturated groups such as itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α, β-unsaturated compounds such as acrylonitrile and methacrylonitrile Saturated nitrile, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride and the like can be mentioned, and these can be used alone or in combination of two or more monomers. Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer. n-Butyl acrylate is particularly preferably used.

  The (meth) acrylic resin has a weight average molecular weight (Mw) of 80,000 or more, particularly preferably in the range of 80,000 to 1,000,000, particularly preferably in the range of 100,000 to 600,000, and in the range of 150,000 to 400,000. Is most preferred.

  There is no restriction | limiting in particular as a manufacturing method of (meth) acrylic resin, You may use any well-known methods, such as suspension polymerization, emulsion polymerization, block polymerization, or solution polymerization. Here, as a polymerization initiator, a normal peroxide type and an azo type can be used, and a redox type can also be used. Regarding the polymerization temperature, suspension or emulsion polymerization may be performed at 30 to 100 ° C, and bulk or solution polymerization may be performed at 80 to 160 ° C. In order to control the reduced viscosity of the obtained copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

  A commercially available product can also be used as the (meth) acrylic resin. For example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dialal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electrochemical Industry Co., Ltd.) and the like can be mentioned. . Two or more acrylic resins can be used in combination.

  A cycloolefin resin is a polymer resin containing an alicyclic structure. A preferred cycloolefin resin is a resin obtained by polymerizing or copolymerizing a cyclic olefin. Examples of the cyclic olefin include norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetracyclododecene, tetracyclo [7.4.0.110, 13.02,7] trideca-2,4. Unsaturated hydrocarbons of polycyclic structures such as 6,11-tetraene and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene, cyclo Examples thereof include monocyclic unsaturated hydrocarbons such as octene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene, cycloheptene, cyclopentadiene, cyclohexadiene, and derivatives thereof. These cyclic olefins may have a polar group as a substituent. Examples of the polar group include a hydroxyl group, a carboxyl group, an alkoxyl group, an epoxy group, a glycidyl group, an oxycarbonyl group, a carbonyl group, an amino group, an ester group, and a carboxylic acid anhydride group. Or a carboxylic anhydride group is preferred. Preferred cycloolefin resins may be those obtained by addition copolymerization of monomers other than cyclic olefins. Addition copolymerizable monomers include ethylene, propylene, 1-butene, 1-pentene, and other ethylene or α-olefins; 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl- Examples include dienes such as 1,4-hexadiene and 1,7-octadiene.

  The cycloolefin resin is obtained by an addition polymerization reaction or a metathesis ring-opening polymerization reaction. The polymerization is carried out in the presence of a catalyst. Examples of the addition polymerization catalyst include a polymerization catalyst composed of a vanadium compound and an organoaluminum compound. As a catalyst for ring-opening polymerization, a polymerization catalyst comprising a metal halide such as ruthenium, rhodium, palladium, osmium, iridium, platinum, nitrate or acetylacetone compound and a reducing agent; or titanium, vanadium, zirconium, tungsten, molybdenum And a polymerization catalyst composed of a metal halide such as acetylacetone compound and an organoaluminum compound. The polymerization temperature, pressure and the like are not particularly limited, but the polymerization is usually carried out at a polymerization temperature of -50 ° C to 100 ° C and a polymerization pressure of 0 to 490 N / cm2.

  The cycloolefin resin is preferably a resin obtained by polymerizing or copolymerizing a cyclic olefin, followed by a hydrogenation reaction to change the unsaturated bond in the molecule to a saturated bond. The hydrogenation reaction is performed by blowing hydrogen in the presence of a known hydrogenation catalyst. Examples of hydrogenation catalysts include cobalt acetate / triethylaluminum, nickel acetylacetonate / triisobutylaluminum, transition metal compounds such as titanocene dichloride / n-butyllithium, zirconocene dichloride / sec-butyllithium, tetrabutoxytitanate / dimethylmagnesium / alkyl. Homogeneous catalyst consisting of a combination of metal compounds; heterogeneous metal catalyst such as nickel, palladium, platinum; nickel / silica, nickel / diatomaceous earth, nickel / alumina, palladium / carbon, palladium / silica, palladium / diatomaceous earth And a heterogeneous solid-supported catalyst in which a metal catalyst such as palladium / alumina is supported on a carrier.

  Examples of the cycloolefin resin include the following norbornene resins. The norbornene-based resin preferably has a norbornene skeleton as a repeating unit. Specific examples thereof include, for example, JP-A-62-252406, JP-A-62-2252407, and JP-A-2-133413. JP, JP 63-145324, JP 63-264626, JP 1-224017, JP 57-8815, JP 5-2108, JP 5-39403. JP-A-5-43663, JP-A-5-43834, JP-A-5-70655, JP-A-5-279554, JP-A-6-206985, JP-A-7-62028, JP-A-8-176411, JP-A-9-241484, JP-A-2001-277430, JP-A-2003-139 No. 50, JP-A No. 2003-14901, JP-A No. 2003-161832, JP-A No. 2003-195268, JP-A No. 2003-111588, JP-A No. 2003-211589, JP-A No. 2003-268187 Gazette, JP-A-2004-133209, JP-A-2004-309799, JP-A-2005-121183, JP-A-2005-164632, JP-A-2006-72309, JP-A-2006-178191, Although what was described in Unexamined-Japanese-Patent No. 2006-215333, Unexamined-Japanese-Patent No. 2006-268065, Unexamined-Japanese-Patent No. 2006-299199 etc. is mentioned, It is not limited to these. Moreover, these may be used individually by 1 type and may use 2 or more types together. Specifically, ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., Arton manufactured by JSR Corporation, APPEL manufactured by Mitsui Chemicals, Inc. (APL8008T, APL6509T, APL6013T, APL5014DP, APL6015T) and the like are preferably used.

  The molecular weight of the cycloolefin resin is appropriately selected depending on the purpose of use, but it is calculated in terms of polyisoprene or polystyrene measured by gel permeation chromatographic method of cyclohexane solution (toluene solution if the polymer resin does not dissolve). When the weight average molecular weight is usually in the range of 5,000 to 500,000, preferably 8,000 to 200,000, more preferably 10,000 to 100,000, the mechanical strength and molding processability of the molded product are highly balanced and suitable. .

  The plasticizer is not particularly limited. For example, polyhydric alcohol ester plasticizer, glycolate plasticizer, phthalate ester plasticizer, citrate ester plasticizer, fatty acid ester plasticizer, phosphate ester plasticizer. Polycarboxylic acid ester plasticizers, polyester plasticizers, acrylic plasticizers, and the like can be used. Examples thereof include polyhydric alcohol ester plasticizers and polyester plasticizers. A more preferable plasticizer is a polyhydric alcohol ester plasticizer. Two or more plasticizers may be used in combination. In that case, at least one plasticizer is preferably a polyhydric alcohol ester plasticizer.

  The polyhydric alcohol ester plasticizer is a plasticizer comprising an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester.

  The polyhydric alcohol constituting the polyhydric alcohol ester plasticizer is represented by the following general formula (a).

Formula (a) R _1- (OH) _na

However, R ₁ represents an n-valent organic group, na represents a positive integer of 2 or more, and an OH group represents an alcoholic and / or phenolic hydroxyl group. Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these. Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane- Examples include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol and the like. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

  There is no restriction | limiting in particular as monocarboxylic acid which comprises a polyhydric-alcohol ester plasticizer, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto. As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. When a cellulose resin is used as the resin component, it is preferable to add acetic acid because the compatibility with the cellulose resin is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid. Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid. Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof. Examples of preferred aromatic monocarboxylic acids include those in which 1 to 3 alkoxy groups such as alkyl group, methoxy group or ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, biphenylcarboxylic acid, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof. Benzoic acid is particularly preferable. The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. All the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are. The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750.

  The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

  Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

  Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.

  Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

  Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.

  The polyvalent carboxylic acid ester plasticizer is composed of a divalent or higher polyvalent carboxylic acid and an alcohol ester.

  The polyvalent carboxylic acid constituting the polyvalent carboxylic acid ester plasticizer is a 2-20 valent aliphatic polyvalent carboxylic acid, a 3-20 valent aromatic polyvalent carboxylic acid, a 3-20 valent alicyclic ring. And the formula polycarboxylic acid. The polyvalent carboxylic acid is represented by the following general formula (b).

Formula (b) R ₂ (COOH) _mb (OH) _nb

R ₂ is an (mb + nb) -valent organic group, mb is a positive integer of 2 or more, nb is an integer of 0 or more, the COOH group is a carboxyl group, and the OH group is an alcoholic or phenolic hydroxyl group. Examples of preferred polyvalent carboxylic acids include the following, but the present invention is not limited to these. Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving retention.

  There is no restriction | limiting in particular as alcohol which comprises a polyhydric carboxylic acid ester plasticizer, Well-known alcohol and phenols can be used. For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. An alicyclic alcohol such as cyclopentanol or cyclohexanol or a derivative thereof, an aromatic alcohol such as benzyl alcohol or cinnamyl alcohol, or a derivative thereof can also be preferably used. The alcohol used for the polyvalent carboxylic ester plasticizer that can be used in the present invention may be one kind or a mixture of two or more kinds.

  The molecular weight of the polyvalent carboxylic acid ester plasticizer is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improvement in retention, and the smaller one is preferable in terms of moisture permeability and compatibility with cellulose ester.

  Examples of particularly preferred polycarboxylic acid ester plasticizers are shown below, but the present invention is not limited thereto. For example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

  As the polyester plasticizer, a polyester plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be used. As a preferable polyester plasticizer, for example, an aromatic terminal ester plasticizer represented by the following general formula (c) can be used.

General formula (c) B- ( _GA ) _nc -GB
In the formula, B is an aromatic carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms, A Represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and nc represents an integer of 1 or more.

  The aromatic terminal polyester plasticizer may be, for example, a benzene monocarboxylic acid residue represented by B and an alkylene glycol residue, oxyalkylene glycol residue or aryl glycol residue represented by G, or A in general formula (c). It is comprised from the alkylene dicarboxylic acid residue or aryl dicarboxylic acid residue shown, and is obtained by reaction similar to a normal polyester plasticizer.

  Examples of the benzene monocarboxylic acid component of the aromatic terminal polyester plasticizer include benzoic acid, para-tert-butyl benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethyl benzoic acid, ethyl benzoic acid, normal propyl benzoic acid, There are aminobenzoic acid, acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms of the aromatic terminal polyester plasticizer include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, and 1,3-butanediol. 1,2-propanediol, 2-methyl 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl -1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2- There are til 1,3-hexanediol, 2-methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Used as a mixture of two or more. In particular, an alkylene glycol having 2 to 12 carbon atoms is particularly preferable because of excellent compatibility with a cellulose ester.

  Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal polyester plasticizer include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, and the like. It can be used as a seed or a mixture of two or more.

  Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal polyester plasticizer include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedicarboxylic acid. These are each used as one or a mixture of two or more. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5 naphthalene dicarboxylic acid, and 1,4 naphthalene dicarboxylic acid.

  The polyester plasticizer has a number average molecular weight of preferably 300 to 1500, more preferably 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxyl value is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxyl value is 15 mgKOH / g or less.

  As for content of a plasticizer, 3-20 mass% is preferable with respect to all the components which comprise an optical film. Two or more kinds of plasticizers may be used in combination, and in that case, the total content thereof may be within the above range.

  The ultraviolet absorber is intended to improve durability by absorbing ultraviolet rays of 400 nm or less, and in particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, and further Preferably it is 2% or less. The ultraviolet absorber is not particularly limited, and examples thereof include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders, and the like. . For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear and side Chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc., and tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, etc. These are commercially available products manufactured by Ciba Specialty Chemicals and can be preferably used.

  Preferred ultraviolet absorbers are benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, and triazine ultraviolet absorbers, and particularly preferred are benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers. In addition, a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as the ultraviolet absorber.

  As the UV absorber, a polymer UV absorber can be preferably used, and in particular, a polymer type UV absorber described in JP-A-6-148430 is preferably used.

  The content of the ultraviolet absorber is preferably 0.5 to 10% by weight, particularly 0.6 to 4% by weight, based on the resin component constituting the optical film. Two or more kinds of ultraviolet absorbers may be used in combination, and in that case, the total content thereof may be within the above range.

  Antioxidants are also referred to as deterioration inhibitors. The antioxidant is preferably used particularly when a cellulose resin is used as the resin component.

  As the antioxidant, hindered phenol compounds are preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-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-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3 , 5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanate Nurate etc. can be mentioned. In particular, 2,6-di-t-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] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

  The content of the antioxidant is preferably from 1 ppm to 1.0% by weight, particularly preferably from 10 to 1000 ppm, based on the resin component constituting the optical film. Two or more kinds of antioxidants may be used in combination, and in that case, the total content thereof may be within the above range.

  The optical film of the present invention may have a single layer structure, or may have a multilayer structure in which a surface layer is provided on a base material layer. When the optical film of the present invention has a multilayer structure, the resin constituting the surface layer and the resin constituting the base material layer are each independently selected from the resins exemplified as the film constituting resin, even though they are made of the same resin. May be.

(Optical film manufacturing method)
The optical film manufacturing method according to the present invention is a conventionally known optical film manufacturing method such as a so-called solution casting method or a melt casting method, wherein the center line average roughness Ra of the surface of one surface of the optical film is It has the uneven | corrugated formation process which forms an unevenness | corrugation in the polymer film surface so that above-described formula may be satisfy | filled. Preferably, the unevenness forming step is performed so that the other surface of the optical film is smooth. Hereinafter, although the manufacturing method of the optical film of this invention is demonstrated using FIG.3, 4, it is not restrict | limited to these embodiment. FIG. 3 is a schematic configuration diagram of a production apparatus for explaining an example of a method for producing an optical film according to the present invention by a solution casting method. In FIG. 4, it is a schematic block diagram of the manufacturing apparatus for demonstrating an example of the method to manufacture the optical film which concerns on this invention by the melt casting method.

  For example, in the solution casting method shown in FIG. 3, a casting step of casting a dope obtained by dissolving or dispersing the above film raw material in a solvent from the casting die 101 onto the support 100, and from the cast dope to the solvent. A solvent evaporation step for evaporating the substrate on the support 100, a peeling step for peeling the polymer film obtained by evaporating the solvent from the support 100 using the peeling roll 102, and an unevenness forming the unevenness on the surface of the polymer film by the mold roll 104 A forming step, a stretching step in which the polymer film 105 is stretched in at least one of the width direction and the transport direction in the tenter 106, a drying step in which the polymer film is dried in the drying device 107, and an optical film is obtained. A winding process is sequentially performed in which the winding machine 108 winds the winding core around the winding core in a multilayer shape. In FIG. 3, the unevenness forming process is performed between the peeling process and the stretching process, but is not particularly limited as long as the predetermined unevenness is formed, and is performed between the stretching process and the drying process or between the drying process and the winding process. May be.

  The concentration of the resin component in the dope is preferably 10 to 35% by mass, and more preferably 15 to 25% by mass. As the solvent used for the dope, a solvent capable of dissolving at least the resin component is used, and a solvent capable of simultaneously dissolving the resin component and the additive is preferably used. The solvent may be used alone or in combination of two or more. However, it is preferable from the viewpoint of production efficiency that a good solvent and a poor solvent of the resin are mixed, and the more the good solvent, the more the resin dissolves. From the viewpoint of sex. The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what melt | dissolves the resin to be used independently is defined as a good solvent, and a solvent that swells or does not dissolve alone is defined as a poor solvent. The good solvent is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. When a cellulose resin or a (meth) acrylic resin is used as the resin, particularly preferable good solvents include methylene chloride or methyl acetate. Although a poor solvent is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably.

  For example, in the melt casting method shown in FIG. 4, a casting process in which the melt of the film raw material described above is cast from the casting die 301 onto the first cooling roll 302 and pressed by the touch roll 303 is performed. A cooling step in which the melt is wound around the second cooling roll and the third cooling roll and cooled, a peeling step in which the polymer film obtained by cooling is peeled off from the roll by the peeling roll 306, a mold roll on the surface of the polymer film An unevenness forming process for forming unevenness by 307, a stretching process in which the polymer film is stretched in at least one of the width direction and the conveying direction in the tenter 309, and the polymer film (optical film) around the core by the winder 310 The winding process of winding up into multiple layers is sequentially performed. In FIG. 4, the unevenness forming step is performed between the peeling step and the stretching step, but is not particularly limited as long as the predetermined unevenness is formed, and may be performed between the stretching step and the winding step.

  Hereinafter, the unevenness forming step will be described in detail. The description of the unevenness forming step is common to both the solution casting method and the melt casting method unless otherwise specified.

  The unevenness forming method employed in the unevenness forming step is not particularly limited as long as desired unevenness can be imparted to the film. For example, a method of transferring the uneven shape of the mold to the film by pressing the film with the mold is used. FIGS. 3 and 4 show a roll plate press system in which irregularities are transferred onto the surface of the polymer film using the mold rolls 104 and 307, but the present invention is not limited to this. For example, a plate press system, a continuous belt, etc. A plate press method may be used. The roll plate press method is preferred.

  When the roll plate press method is adopted, as shown in FIG. 3, the polymer film may be alternately wound around the transport roll 103 and the mold roll 104 to transfer the surface shape of the mold roll onto the polymer film. Alternatively, as shown in FIG. 4, the polymer film may be passed between the back roll 308 and the mold roll 307 to transfer the surface shape of the mold roll to the polymer film. In the former case, the transfer rate can be controlled by the conveyance tension of the film, the number of mold rolls around which the film is wound, and the holding angle of the film with respect to the mold roll. The transfer rate increases as the conveyance tension increases or the number of mold rolls increases. The film transport tension is preferably 60 to 300 N per 1000 mm width, for example. In the latter case, the transfer rate can be controlled by the pressing force of the mold roll against the back roll. Such a pressing force is preferably 150 to 250 kg / cm.

  When manufacturing a film by the solution casting method, the residual solvent amount of the polymer film subjected to the unevenness forming step is preferably 20 to 100%. The amount of residual solvent in the polymer film can be adjusted by changing the location of the mold roll, adjusting the drying conditions in the solvent evaporation process, the solid concentration of the dope, the film transport speed, etc. It can be controlled by spraying, coating, or solvent mist. The transfer rate can also be controlled by adjusting the residual solvent amount.

  In the present specification, the amount of residual solvent can be represented by the following formula.

    Residual solvent amount (% by mass) = {(MN) / N} × 100

  In the formula, M is a mass of the film at a predetermined point, and N is a mass when M is dried at 110 ° C. for 3 hours. In particular, M when calculating the residual solvent amount of the polymer film subjected to the unevenness forming step is the mass of the web immediately before the unevenness forming step.

  In the case of producing a film by the melt casting method, the temperature of the polymer film subjected to the unevenness forming step is preferably Tg to Tg + 80 ° C. when the glass transition temperature of the film is Tg (° C.). In this case, it is preferable to set the surface temperature of the mold roll so that the film temperature is within the above range. The transfer rate can also be controlled by adjusting the temperature of the polymer film and the mold roll.

  The mold rolls 104 and 307 have unevenness on the outer peripheral surface corresponding to the predetermined unevenness that the film surface should have. In particular, in the case of manufacturing an optical film roll having a gradient in which one surface satisfies the above formula and Ra decreases or increases from the center to both ends in the width direction, such unevenness (especially , Ra), a mold roll having irregularities corresponding to the surface is used. The surface irregularities of the mold roll may be formed by a sand blast method, a micro blast method, a chemical etching method, a brush process, or may be formed by a manual process.

  The transfer rate is usually 1 to 50%. When trying to achieve a transfer rate exceeding 50%, the residual solvent amount of the film is too high and the film cannot be sufficiently peeled off from the mold roll, or the film is too high in transport tension and breaks during transport. It is not preferable.

  In this specification, the transfer rate uses the ratio of Ra of the optical film obtained after transfer processing to Ra on the mold roll surface. The transfer process may be performed before stretching or may be performed after stretching. However, the transfer rate here does not include attenuation of unevenness due to stretching when stretching is performed after the transfer process.

  As the back roll 308, a mirror finish roll is usually used. The surface roughness Ra of the back roll is preferably 10 nm or less, more preferably 5 nm or less.

  In the method for producing an optical film of the present invention, a knurling step may be performed immediately before the winding step to form knurling portions at both ends in the width direction of the film.

  A knurling process is a process of providing a knurling part in the both-sides edge part of a film about a film width direction. A knurling part is a convex part which protruded from a non-working field at predetermined height, and blocking can be prevented still more effectively by forming the knurling part. The surface on which the knurling portion is formed may be a surface to be brought into contact with the mold roll, may be a surface opposite to the surface, or may be both surfaces thereof.

  The height of the knurling portion is set to a range of 0.05 to 0.3 times the film thickness T, and the width (length in the width direction) is set to a range of 0.005 to 0.02 times the film width L. The For example, when the film thickness is 40 μm and the film width is 1000 mm, the height of the knurling portion is set to 2 to 12 μm and the width is set to 5 to 20 mm. The knurling part is usually formed continuously over the entire length in the transport direction.

  The knurling process is usually accomplished by an embossing device.

  You may implement the static elimination process of a film between a knurling process and a winding-up process.

(Use)
The optical film of the present invention is particularly suitable for use as, for example, a polarizing plate protective film, a viewing angle widening film, a retardation film, and the like.

  When using the optical film of this invention as a protective film for polarizing plates, a polarizing plate can be produced by a general method. It is preferable that an adhesive layer is provided on the back side of the optical film of the present invention, and is bonded to at least one surface of a polarizer produced by immersion and stretching in an iodine solution. On the other side, the optical film of the present invention may be used, or another protective film for polarizing plate may be used. For example, a commercially available cellulose ester film (for example, Konica Minoltac KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC8UE, KC4UE, KC4FR-3, C4 -1, KC8UY-HA, KC8UX-RHA, Konica Minolta Opto Co., Ltd.) and the like are preferably used. A polarizer, which is a main component of a polarizing plate, is an element that transmits only light having a plane of polarization in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed. For the polarizer, a polyvinyl alcohol aqueous solution is formed into a film and dyed by uniaxial stretching or dyed or uniaxially stretched and then preferably subjected to a durability treatment with a boron compound.

  By incorporating the polarizing plate bonded with the optical film of the present invention into a liquid crystal display device, various liquid crystal display devices with excellent visibility can be produced. In particular, it is preferably used for a liquid crystal display device for outdoor use such as a large-sized liquid crystal display device or digital signage. The polarizing plate according to the present invention is bonded to a liquid crystal cell via the adhesive layer or the like.

  The polarizing plate according to the present invention includes a reflective type, a transmissive type, a transflective type LCD, a TN type, an STN type, an OCB type, a HAN type, a VA type (PVA type, MVA type), an IPS type (including an FFS type), and the like. It is preferably used in LCDs of various driving methods. In particular, in a large-screen display device having a screen size of 30 or more, especially 30 to 54, there is no white spot at the periphery of the screen, and the effect is maintained for a long time.

  In addition, there was little color unevenness, glare and wavy unevenness, and the eyes were not tired even during long-time viewing.

[Experiment 1]
<Example 1A>
(Preparation of dope)
Various components were blended in the following proportions to prepare a dope.

Cellulose acetate propionate (CAP) 100 parts by weight (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8, Mn = 70000, Mw = 220,000, Mw / Mn = 3.14)
Polyhydric alcohol ester plasticizer (trimethylolpropane benzoate)
5 parts by weight Aromatic-terminated polyester plasticizer (trimethylolpropane benzoate)
15 parts by weight Methylene chloride 430 parts by weight Ethanol 40 parts by weight

  The above materials are sequentially put into a sealed container, the temperature in the container is raised from 20 ° C. to 80 ° C., and the mixture is stirred for 3 hours while maintaining the temperature at 80 ° C. to obtain cellulose acetate propionate. Dissolved completely. Then, stirring was stopped and the liquid temperature was lowered to 43 ° C. The dope was filtered using a filter paper (Azumi filter paper No. 244, manufactured by Azumi Filter Paper Co., Ltd.) to obtain a dope.

(Manufacture of optical films)
The apparatus shown in FIG. 3 except that the number of mold rolls 104 is increased to 5 and the number of transport rolls 103 is increased to 6 in the concavo-convex forming step, and the film is alternately wound around the transport roll and the mold roll. An optical film roll was manufactured by the same apparatus.

  The dope was cast from the die 101 onto a mirror-treated stainless steel support belt 100. The dope temperature was 35 ° C. and the support temperature was 25 ° C. After the dope film on the support was dried with a drying air of 44 ° C., when the residual solvent amount of the dope film was dried to 100% by weight, the web was supported by the peeling roll 102 at a peeling tension of 162 N / m. Peeled off. When the residual solvent amount of the film after peeling reached 80% by weight, the mold roll 104 was brought into contact with the web surface to transfer the uneven shape. Specifically, the conveyance tension was 180 N in the unevenness forming step. The polymer film was wound so as to wrap at 90 degrees on the mold roll. All the mold rolls had Ra having substantially uniform irregularities (Ra and Sm) in the axial direction, and had the irregularities having Ra and Sm shown in Table 1. The film to which the concavo-convex shape was transferred was stretched 30% in the width direction of the film while holding both ends of the film with clips using a tenter 106 to prepare a polymer film. At this time, the stretching temperature was 140 ° C. The produced film was dried in a drying apparatus 107 with 120 ° C. drying air. The film thickness was 40 μm. The resulting film was slit to a width of 1980 mm and then subjected to a knurling process with a width of 10 mm and a height of 5 μm at both ends, with an initial tension of 300 N, a taper of 100%, and a corner of 30%. It was wound on (core). The non-contact surface with the mold roll is a non-contact surface with the support in the casting process, and is referred to as A surface. The contact surface with the mold roll is a contact surface with the support in the casting process, and is referred to as B surface.

<Example 1B, 1D-9D / Comparative Examples 1A-3A, 1B-3B, 1D>
The resin was changed in the dope preparation process, the mixing ratio of CAP and acrylic resin was set to 50:50 by weight ratio, a predetermined amount of inorganic fine particles were further contained in the dope, and the roll transfer position was adjusted. The residual solvent amount of the film when transferring the concavo-convex shape was controlled to the value shown in Table 1, and the mold roll shown in Table 1 was used in the concavo-convex forming step, and the number of rolls was shown. An optical film roll was obtained in the same manner as in Example 1A, except that the number of the transfer rates shown in 1 was achieved. All the mold rolls had a substantially uniform uneven shape (Ra and Sm) in the width direction.

  As the acrylic resin, Dianal BR85 (manufactured by Mitsubishi Rayon Co., Ltd.) Mw 280000 was used.

  As “IPA-ST”, a silicon dioxide fine particle dispersion (average particle diameter: 10 nm; organosilica sol IPA-ST, manufactured by Nissan Chemical Industries, Ltd.) was used.

  As "Aerosil 200V", what was processed with the following method was used. Aerosil 200V (primary particle size: 12 nm, manufactured by Nippon Aerosil Co., Ltd.) was stirred for 30 minutes at a rotation speed of 500 rpm, and then passed through a Manton Gorin type high-pressure disperser (H20 type; manufactured by Sanwa Kikai Kogyo Co., Ltd.) three times. . The load pressure at this time was 25 MPa. The average dispersed particle size (secondary particle size) was 100 nm.

  As “Aerosil R812”, a material obtained by treating Aerosil R812 (primary particle size: 8 nm, manufactured by Nippon Aerosil Co., Ltd.) in the same manner as “Aerosil 200V” was used. The average dispersed particle size (secondary particle size) was 80 nm.

<Example 1C>
(Preparation of pellets)
100 parts by mass of ZEONOR 1420 (manufactured by Nippon Zeon Co., Ltd.) as the cycloolefin resin, 0.3 parts by mass of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) as the phenolic antioxidant, and pentaerythritol tetrakis [3- (3, 5-Di-tert-butyl-4-hydroxyphenyl) propionate] (commercially available, Irganox 1010 (manufactured by Ciba Specialty Chemicals)) 0.5 parts by mass, and phosphorus compound as tetrakis (2,4-di-t-butyl) -5-methylphenyl) -4,4'-biphenylenediphosphonite (as a commercial product, 0.3 part by mass of GSY-P101 (manufactured by Sakai Chemical Industry Co., Ltd.)) was mixed and dried under reduced pressure at 60 ° C for 5 hours. This resin composition was melt-mixed at 235 ° C. using a twin-screw extruder and then dried to obtain pellets. At this time, an all screw type screw was used instead of a kneading disk in order to suppress heat generation due to shearing during kneading. In addition, evacuation was performed from the vent hole, and volatile components generated during kneading were removed by suction. In addition, the moisture between the feeder, hopper, and the extruder die supplied to the extruder and the cooling tank was set as a dry nitrogen gas atmosphere to prevent moisture from being absorbed into the resin.

(Manufacture of optical films)
The optical film roll was manufactured with the apparatus shown in FIG.

  The pellets are supplied to an extruder (not shown) and melted, and the melt at 270 ° C. is melt-extruded from the die 301 onto the first cooling roll 302 having a surface temperature of 130 ° C. A cast film was obtained. At this time, a die 301 having a lip clearance of 1.5 mm and a lip portion average surface roughness Ra of 0.01 μm was used. The first cooling roll 302, the second cooling roll 304, and the third cooling roll 305 were made of stainless steel having a diameter of 40 cm, and the surface was subjected to hard chrome plating. Further, oil for temperature adjustment was circulated inside to control the roll surface temperature. The touch roll 303 had a diameter of 20 cm, the inner cylinder and the outer cylinder were made of stainless steel, and the surface of the outer cylinder was hard chrome plated. The wall thickness of the outer cylinder was 2 mm, and the surface temperature of the elastic touch roll was controlled by circulating oil for temperature adjustment in the space between the inner cylinder and the outer cylinder. Thereafter, the film was pressed on the first cooling roll 302 with a touch roll 303 having a 2 mm thick metal surface at a linear pressure of 10 kg / cm. The film temperature on the touch roll side during pressing was 180 ° C. ± 1 ° C. The film temperature on the touch roll side at the time of pressing here is a state in which there is no touch roll when the touch roll on the first cooling roll is in contact with the touch roll using a non-contact thermometer. The average value of the film surface temperature measured 10 points in the width direction from a position 50 cm away. The glass transition temperature Tg of this film was 137 ° C. The glass transition temperature Tg was determined by measuring the glass transition temperature of a film extruded from a die by DSC method (in nitrogen, temperature rising temperature 10 ° C./min) using DSC6200 (manufactured by Seiko Co., Ltd.). The surface temperature of the touch roll was 130 ° C., and the surface temperature of the second cooling roll was 100 ° C. The surface temperature of each roll of the touch roll, the first cooling roll, the second cooling roll, and the third cooling roll is the temperature of the roll surface at a position 90 ° before the rotation direction from the position where the film first contacts the roll. The average value measured at 10 points in the width direction using a non-contact thermometer was defined as the surface temperature of each roll.

  Thereafter, the film was passed between a pair of rolls consisting of a mold roll 307 and a back roll 308 to transfer the irregularities. At this time, the mold roll was kept at 180 ° C., and the linear pressure was 200 kg / cm. The mold roll had substantially uniform irregularities (Ra and Sm) in the axial direction, and had irregularities having Ra and Sm shown in Table 1. The surface temperature of the back roll was 100 ° C., and the surface roughness was Ra 3.2 nm and Sm 4.4 μm. Subsequently, the film is introduced into a tenter 309 having a preheating zone, a stretching zone, a holding zone, and a cooling zone (there is also a neutral zone for ensuring thermal insulation between the zones), and 160 ° C. in the width direction. And stretched 30%. Thereafter, it is cooled to 70 ° C., then released from the clip, the clip gripping part is cut off, the film is knurled at a width of 10 mm and a height of 5 μm, slit at a width of 1980 mm, an initial tension of 300 N, and a taper On the condition of 100% and corners of 30%, 5000 m was wound around a 15 cm outer diameter core. The film thickness was 40 μm. The non-contact surface with the mold roll is a contact surface with the touch roll in the casting process, and is referred to as A surface. The contact surface with the mold roll is the contact surface with the first cooling roll in the casting process, and is referred to as the B surface.

<Comparative Examples 1C to 3C>
An optical film roll was produced in the same manner as in Example 1C, except that the pellet was further added with a predetermined amount of predetermined inorganic fine particles in the pellet preparation step, and the mold roll shown in Table 1 was used in the irregularity formation step. Got. The mold roll had substantially uniform unevenness (Ra and Sm) in the axial direction.

  As “KE-P10”, a silicon dioxide fine particle dispersion (Seahoster KE-P10, primary particle size: 100 nm (manufactured by Nippon Shokubai Co., Ltd.)) having an average particle diameter of 100 nm was used.

<Evaluation>
(Measurement of Ra and Sm)
Ra and Sm of the A surface and the B surface in the optical film were measured by the method described above.

(Calculation of load P)
P was calculated based on the formula (2).

(Measurement of elastic modulus E)
The elastic modulus in both directions in the film transport direction (MD direction) and the direction orthogonal to the transport direction (TD direction)
Using a tensile tester manufactured by Toyo Seiki Seisakusho Co., Ltd. according to 527-3, a tensile test was performed at 23 ° C. and 55% RH, and the tensile strength was obtained from 10% strain strength data. For example, the elastic modulus in the MD direction of the optical film of Example 1A was 2890 MPa, the elastic modulus in the TD direction was 3121 MPa, and the average value was 3006 MPa.

(Calculation of section moment of inertia I)
I was calculated based on the formula (3).

(Calculation of the value on the right side of Equation (1))
Calculation was performed based on the obtained P, Sm, E, and I.

(blocking)
The optical film roll was stored at 40 ° C. and a relative humidity of 80% RH for 1 week, and then the film was unwound and evaluated. Specifically, a film having a length of 1000 m was unwound from the winding core, and the occurrence of blocking such as sticking or convexity was evaluated as follows.

-Sticking failure;
A: No sticking failure occurred;
○: It was good that only a failure occurred by sticking to the center of the film 100 m from the winding core:
Δ: Although a failure occurred due to sticking to the center of the film 500 m from the winding core, there was no practical problem:
X: A failure occurred due to sticking at the center of the film 1000 m from the winding core, and there was a problem in practical use.

・ Convex failure;
A: No convex failure occurred at all;
○: Only a convex failure occurred at the end of the film 100 m from the core, which was good:
Δ: Convex failure occurred at the end of the film 500 m from the winding core, but there was no practical problem:
X: A convex failure occurred at the end of the film 1000 m from the winding core, and there was a problem in practical use.

(Haze)
The film was unwound from the optical film roll, and arbitrary three points were measured by Haze Meter NDH2000 (manufactured by Nippon Denshoku) based on JIS-K6714, and the average value HA was determined.

A: HA <0.10;
○: 0.10 ≦ HA <0.50;
Δ: 0.50 ≦ HA <1.00) (no practical problem);
X: 1.00 ≦ HA (problematically problematic).

(Dynamic friction coefficient)
The dynamic friction coefficient between the film surface and the back surface was measured according to JIS-K-7125 (1987). Specifically, the film sheet is cut out from the optical film roll, placed so that the front and back surfaces of the film are in contact with each other, a 150 g weight is placed, and the weight is leveled under the conditions of a sample moving speed of 100 mm / min and a contact area of 30 mm × 30 mm. The load (F) when the tension and weight were moving was measured, and the dynamic friction coefficient was obtained from the following formula.

    Coefficient of dynamic friction = F (gf) / weight P (gf)

  Optical films were prepared in the same manner as in Examples 1B and 1D to 9D, except that the mixing ratio of CAP and acrylic in Examples 1B and 1D to 9D was 5:95 by weight. As a result, blocking did not occur as in 1B and 1D to 9D, and the haze and dynamic friction coefficient were good.

[Experiment 2]
<Examples 1E to 12E>
In the pellet preparation step, a predetermined amount of inorganic fine particles were further contained in the pellet, and in the unevenness formation step, Ra was continuously changed from the center to both ends in the axial direction, but Sm was axial An optical film roll was obtained in the same manner as in Example 3D, except that a substantially uniform mold roll (see Table 3) was used.

<Evaluation>
The optical film was unwound from the optical film roll, the sample was prepared from the center, one end and the other end in the width direction, and measurement or calculation of each value on the optical film B surface and A surface, Performed for each of the center part, one end part and the other end part, using a sample prepared from the center part as an evaluation sample for sticking failure, and a sample prepared from the end part as an evaluation sample for convex failure The evaluation was performed by the same method as the evaluation method of Experimental Example 1 except that was used. Each value at one end was the same as at the other end.

  As a result, as shown in Table 4, in Examples 1E to 4E, after the blocking test, no sticking failure occurred at the width center. In Examples 7E to 10E, after the blocking test, the convex failure that was likely to occur near the width end portion did not occur at all, and the film was easily unwound from the roll.

  The present invention has wide industrial applicability in the technical field of optical films.

Claims (5)

Concave and convex forming step of forming concavities and convexities by a mold roll on the polymer film surface containing a resin and the content of fine particles with respect to the resin component is 0.2% by weight or less,
A winding step of winding the optical film on which the irregularities are formed by the irregularity forming step in a multilayer shape around the core, and a method for producing an optical film roll,
The unevenness average distance Sm (mm) of one surface of the optical film on which the unevenness is formed by the mold roll in the unevenness forming step is 1 × 10 ^{−3 to} 12 × 10 ⁻³ , and the one surface is Formula (1):
Ra ≧ 3.125 × P × Sm ³ / (E × I) (1)
[In formula (1), Ra is the center line average roughness (mm) of the film surface;
P is a load (N) applied between adjacent convex portions of the film surface due to the tension at the time of winding the film, and the formula (2):
P = (F / x) × Sm (2)
(In formula (2), x is the film width (mm) at the time of winding the film; F is the film tension (N) at the time of winding the film); Sm is the film surface Uneven spacing (mm);
E is the elastic modulus (MPa) of the film;
I is the formula (3):
I = (Sm × t ³ ) × 10 ⁻³ / 12 (3)
(In Formula (3), Sm is the same as defined in Formula (2); t is the film thickness (mm) of the film) and is the sectional moment of inertia (mm ⁴ ) of the film]. The manufacturing method of the optical film roll characterized by the above-mentioned.   The method for producing an optical film roll according to claim 1, wherein the other surface with respect to the one surface has a center line average roughness Ra of 5 nm or less.   The center line average roughness Ra of said one surface is 0.4-70 nm, The manufacturing method of the optical film roll of Claim 1 or 2.   The manufacturing method of the optical film roll in any one of Claims 1-3 in which the said resin contains a cellulose resin.   The method for producing an optical film roll according to claim 1, wherein the resin contains a (meth) acrylic resin.

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