JP2010089298A - Method for manufacturing optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical film provided with an unevenness with a flat face excellent in smoothness at its front end of a projection. <P>SOLUTION: The method for manufacturing the optical film has the projection reforming process for forming the flat face at the front end of the projection by pressing a smooth roll 4 on an unevenness forming face of a polymer film 1 on the surface of which an unevenness is formed. In the method for manufacturing the optical film, the total area of the flat face formed at the front end of the projection is 20-80% of the whole unevenness forming face. In the method for manufacturing the optical film, the height of the projection after the flat face is formed is 20-80% of the height of the projection before the flat face is formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing an optical film provided with irregularities having a flat surface at the tip of a convex portion.

  As an optical film, an optical film having a flat surface at the tip of a convex portion in the unevenness provided on the surface is known. Such a convex flat film is useful as a prism sheet, a lens sheet, a diffraction grating, and a non-reflective structure because light scattering at the top of the convex part is small and visibility is excellent.

  The convex flat film is generally manufactured by transferring the irregularities of the mold at a transfer rate of 100%. For example, in Patent Document 1, when a concavo-convex pattern is thermally transferred to a film using a mold, a flat surface is formed in advance in a portion corresponding to the tip of the convex portion of the film in the mold.

  However, in the above-described technique, when the mold is released from the film, the resin is peeled off from the film and transferred to the mold, and a resin residue remains on the mold. In particular, the resin residue remained remarkably on the flat surface of the mold. As a result, a film defect occurred on the flat surface at the tip of the convex portion of the film, or foreign matter adhered, resulting in a decrease in smoothness. For this reason, improvements have been made, such as making the resin composition of the film easy to release from the mold, but not so much.

Furthermore, in the above technique, since only one type of uneven shape can be formed from one mold, the degree of freedom of the uneven shape imparted to the film is low.
Japanese Patent Laid-Open No. 9-26503

  An object of this invention is to provide the method of manufacturing the optical film by which the unevenness | corrugation which has the flat surface excellent in smoothness was provided to the convex part front-end | tip.

  The present invention provides a method for producing an optical film comprising a convexity correcting step of pressing a smooth roll against a concavo-convex forming surface of a polymer film having a concavoconvex surface to form a flat surface at the tip of the convex portion. Regarding the method.

According to the present invention, it is possible to manufacture an optical film in which unevenness having a flat surface excellent in smoothness is imparted to the tip of a convex portion.
In addition, in the present invention, after forming irregularities on the film, the flat surface is formed by pressing the smooth roll to form the flat surface at the tip of the convex portion. The uneven shape such as the ratio, the smoothness, and the height of the convex portion can be controlled. Therefore, the degree of freedom of the formed uneven shape is relatively high.
By adjusting the ratio of the surface roughness of the smooth roll and the height of the convex portion after forming the flat surface to the height of the convex portion before forming the flat surface within a predetermined range, the smoothness of the flat surface is further increased. Can be improved. Furthermore, crushing of the concave portion, which is a particular problem of the present invention, can be suppressed.

  The manufacturing method of the optical film which concerns on this invention performs the convex part correction process which presses a smooth roll against the uneven | corrugated formation surface of the polymer film in which the unevenness | corrugation was formed on the surface, and corrects a convex part. Hereinafter, the unevenness forming step and the convex portion correcting step will be described in detail with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram showing an embodiment of an apparatus for carrying out the method for producing an optical film of the present invention. FIG. 2A is a schematic cross-sectional view of a polymer film showing an example of a concavo-convex shape just before the flat surface is formed, and FIG. 2B is a schematic cross-sectional view of a polymer film showing an example of the concavo-convex shape after the flat surface is formed. It is. In the present specification, a polymer film having irregularities but having a flat surface on the convex portion is simply referred to as an “uneven film”, and a polymer film having a flat surface on the convex portion is simply referred to as “flat convex portion”. It shall be called “film”. In addition, the surface of the polymer film on which the irregularities are formed is referred to as a first surface (1a in the figure), and the back surface is referred to as a second surface (1b in the figure).

(Unevenness forming process)
The method for forming irregularities on the first surface 1a of the polymer film 1 is not particularly limited. For example, as shown in FIG. 1, the mold roll 2 is pressed while at least the first surface 1a of the polymer film 1 is softened by heat. The hot press method to transfer the unevenness by the method, while the mold is transferred to the actinic radiation curable resin applied to the substrate, the actinic radiation is irradiated from the substrate side to cure the actinic radiation curable resin, and then released from the mold An actinic radiation curing transfer method, a film transfer method in which a template is transferred in a state where a film during solution film formation or melt film formation is softened, or the like can be employed.

  The mold roll 2 used in the hot press method shown in FIG. 1 may have irregularities on the surface, regularly so that a pattern is formed as a whole, or may have irregularities. . The material of the mold roll 2 may be any material as long as it has rigidity capable of withstanding the pressing pressure, and can be used without limitation, such as metal, glass, ceramics, synthetic resin, composite of synthetic resin and metal and / or glass. The mold can be manufactured by various methods for forming irregularities on the surface of glass or metal. As a method for forming irregularities on the surface of the mold roll, electric discharge machining, shot machining, etching machining, laser machining, or the like can be used. The metal used for the mold is not particularly limited as long as desired irregularities can be imparted, and examples thereof include high carbon steel, chromium-molybdenum steel, stainless steel, aluminum, and copper. For the purpose of curing the mold surface, a quenching process may be performed, or a nitriding surface process such as a canak process may be performed in addition to a plating process such as hard chrome.

  The uneven | corrugated shape which the mold roll 2 has should just be a shape which can form the uneven | corrugated film which has desired uneven | corrugated shape.

  The uneven shape of the uneven film may be arbitrarily selected depending on the use of the convex flat film finally obtained in the present invention. The unevenness of the uneven film preferably has a cross-sectional shape having a top at the tip of the protrusion from the viewpoint of mold release of the resin with respect to the mold roll. As a cross-sectional shape of such a convex portion, for example, a substantially triangular shape can be mentioned. The substantially triangular shape as the cross-sectional shape of the convex part which the concavo-convex film has should just have in the vertical cross section with respect to the width direction of a film, or the vertical cross section with respect to a conveyance direction. The convex part which an uneven | corrugated film has normally has a substantially triangular shape continuously in the width direction of a film in the cross section perpendicular | vertical with respect to the width direction of a film.

  The size of the unevenness of the uneven film is not particularly limited, and for example, the height of the protrusion (h in FIG. 2A) is 100 nm to 100 μm, and the uneven pitch (p in FIG. 2A) is 100 nm to 100 nm. It may be 100 μm. In particular, when the convex portion of the concavo-convex film has a substantially triangular cross section, the apex angle (α in FIG. 2A) is preferably 70 to 130 °, particularly preferably 80 to 120 °.

  The outer diameter of the mold roll 2 is not particularly limited, and an outer diameter of 50 mm or more and 3000 mm or less that can be manufactured as a roll can be applied. However, depending on the point that unevenness is imparted to the film with accuracy and the enlargement of weight is avoided. The outer diameter is substantially 50 mm or more and 2000 mm or less.

  The material of the back roll 3 installed facing the mold roll 2 may be any material as long as it has rigidity capable of withstanding the pressing pressure, and is limited to metal, ceramics, synthetic resin, synthetic resin and metal and / or glass composite. It can be used without being.

  There is no particular limitation on the outer diameter of the back roll 3. Although an outer diameter of 50 mm or more and 3000 mm or less that can be manufactured as a roll can be applied, the outer diameter is substantially 50 mm or more and 2000 mm or less in terms of imparting unevenness to the film with high accuracy and avoiding enlargement of weight. By using the mold roll 2 instead of the back roll 3, irregularities can be accurately formed on both surfaces of the film.

  The press load and press time are not particularly limited as long as the unevenness of the mold can be sufficiently transferred to the film. The press load is usually 0.01 to 10 N / mm, particularly preferably 0.05 to 5 N / mm. In general, the pressing time is preferably 0.001 to 0.1 seconds.

The thickness of the concavo-convex film (T ₁ in FIG. 2A) is not particularly limited as long as the object of the present invention is achieved, and is usually 10 to 200 μm, preferably 30 to 150 μm.

  In particular, the film transport speed in the case of employing the hot press method is preferably 10 to 150 m / min, and more preferably 20 to 120 m / min.

  The polymer that forms the polymer film 1 is not particularly limited, and for example, resins conventionally used in the field of optical films can be used. Specific examples include cellulose ester resins, cycloolefin resins, polycarbonate resins, and the like. More preferably, a film made of a cellulose ester resin is used.

  In the case of using a cellulose ester-based resin, the cellulose as a raw material of the cellulose ester-based resin is not particularly limited, and examples thereof include cotton linters, wood pulp (derived from coniferous trees and hardwoods), kenaf and the like. Moreover, the cellulose ester-type resin obtained from them can be mixed and used in arbitrary ratios, respectively. When the acylating agent is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), these cellulose ester resins use an organic solvent such as acetic acid or an organic solvent such as methylene chloride. It can obtain by making it react with a cellulose raw material using such a protic catalyst.

When the acylating agent is acid chloride (CH ₃ COCl, C ² H ⁵ COCl, C ₃ H ₇ COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804. In addition, the cellulose ester resin used in the present invention is obtained by mixing and reacting the acylating agent according to the degree of substitution, and the acylating agent reacts with the hydroxyl group of the cellulose molecule. Cellulose molecules are composed of many glucose units linked together, and the glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution (mol%). For example, cellulose triacetate has acetyl groups bonded to all three hydroxyl groups of the glucose unit (actually 2.6 to 3.0).

  Cellulose ester resin is a mixed fatty acid ester of cellulose in which propionate group or butyrate group is bonded in addition to acetyl group such as cellulose acetate propionate resin, cellulose acetate butyrate resin, or cellulose acetate propionate butyrate resin. There may be. In addition, the cellulose acetate propionate resin containing a propionate group as a substituent is excellent in water resistance and is useful as a film for a liquid crystal image display device.

  The number average molecular weight of the cellulose ester-based resin is preferably 40000 to 200000, and has a high mechanical strength when molded, and an appropriate dope viscosity in the case of a solution casting method, and more preferably 50000 to 150,000. . The weight average molecular weight (Mw) / number average molecular weight (Mn) is preferably in the range of 1.4 to 4.5.

  In the present specification, the average molecular weight and the molecular weight distribution can be measured by a known method using high performance liquid chromatography. Using this, the number average molecular weight and the weight average molecular weight can be calculated, and the ratio (Mw / Mn) can be calculated.

The measurement conditions are as follows.
Solvent: Methylene chloride column: Shodex K806, K805, K803G (used by connecting 3 products manufactured by Showa Denko KK)
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 = 100000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

The Tg of the polymer forming the polymer film 1 is not particularly limited as long as the object of the present invention is achieved, and may be, for example, 50 to 200 ° C, particularly 70 to 180 ° C.
In this specification, Tg uses the value measured by TMA8310 (made by RIGAKU).

  The polymer film 1 may contain additives such as an ultraviolet absorber, a plasticizer, a matting agent, an antioxidant, a conductive substance, an antistatic agent, a flame retardant, and a lubricant.

  The polymer film 1 may be manufactured by any known method, and can be manufactured by, for example, a so-called solution casting method or a melt casting method.

  The polymer film 1 may be stretched. For example, a film stretched 1.1 to 3 times in each axial direction in two orthogonal axes may be used.

  The polymer film 1 may have a single layer structure made of the resin, or may have a multilayer structure having a surface layer made of the resin on the base material layer.

(Projection correction process)
In this step, the smooth roll 4 is pressed against the irregular surface of the polymer film 1 having irregularities formed on the first surface 1a to form a flat surface 7 at the tip of the convex portion 6 to obtain a convex flat film. The unevenness forming surface is a surface with which the mold roll 2 comes into contact in the unevenness forming step.

  When the smooth roll 4 is pressed against the uneven surface of the polymer film 1, it is only necessary to pass between the smooth roll 4 and the back roll 5 through the polymer film 1 as shown in FIG. 1.

  By adjusting the correction temperature and the correction load, the total area and smoothness of the flat surface in the convex flat film, the convex height, and the maximum convex height can be controlled. When the straightening temperature is increased or the straightening load is increased, the height of the convex portion and the maximum convex portion are lowered, the total area of the flat surface is increased, and the smoothness of the flat surface is improved. When the correction temperature is lowered or the correction load is decreased, the convex height and the maximum convex height are increased, the total area of the flat surface is decreased, and the smoothness of the flat surface is decreased.

The correction temperature is a temperature at which at least the tip of the concavo-convex film should have at the time of contact between the concavo-convex film and the smooth roll. In this specification, the surface temperature of the smooth roll 4 is used. It may be the ambient temperature at which The correction temperature is usually Tg-80 to Tg + 70 ° C. when the glass transition temperature of the polymer film is Tg, and improves the smoothness of the flat surface, controls the total area and height of the flat surface, and crushes the concave portion. From the viewpoint of prevention, Tg−60 to Tg + 40 ° C. is preferable, and Tg−50 to Tg + 30 ° C. is particularly preferable.
The surface temperature of the smooth roll can be controlled by a heater provided inside the roll, and can be measured by a non-contact thermometer.

  The straightening load is a pressing pressure on the film of the smooth roll 4 and is usually 1 to 400 N / mm, and improves the smoothness of the flat surface, controls the total area and height of the flat surface, and crushes the concave portion. From the viewpoint of prevention, it is preferably 2 to 300 N / mm, particularly 5 to 250 N / mm.

The correction time, that is, the contact time between the film and the smooth roll is not particularly limited as long as the object of the present invention is achieved, and is usually 10 ⁻⁵ to 1 second, and particularly preferably 10 ⁻⁴ to 10 ⁻¹ second. .

  The smooth roll 4 should just have a smooth surface on the surface and the rigidity which can endure a press pressure. Examples of the material of the smooth roll 4 include the same materials exemplified as the material of the mold roll 2. For the purpose of curing the smooth roll surface, a quenching treatment may be performed, or a nitriding surface treatment such as a canak treatment may be performed in addition to a plating treatment such as hard chrome.

The surface roughness Ra of the smooth roll 4 is preferably as small as possible, usually 0.5 to 70 nm, and preferably 1 to 50 nm, particularly 1 to 20 nm from the viewpoint of improving the smoothness of the flat surface. A smooth roll with an Ra of 1 nm or less requires a significant cost for production and is not realistic.
The surface roughness Ra is a value based on JIS B 0601 and can be measured by a one-dimensional surface roughness meter SV-3000 (manufactured by Mitutoyo).

  The outer diameter of the smooth roll 4 is not particularly limited, and an outer diameter of 50 mm or more and 3000 mm or less that can be manufactured as a roll can be applied. However, the smoothness is imparted to the flat surface of the convex portion with high accuracy, and the weight is increased. Is an outer diameter of 50 mm or more and 2000 mm or less.

  The material of the back roll 5 installed facing the smooth roll 4 may be any material as long as it has rigidity capable of withstanding the pressing pressure, and is limited to metal, ceramics, synthetic resin, synthetic resin and metal and / or glass composite. It can be used without being.

  There is no particular limitation on the outer diameter of the back roll 5. An outer diameter of 50 mm or more and 3000 mm or less that can be manufactured as a roll can be applied. However, in terms of imparting smoothness to the flat surface of the convex portion with accuracy and avoiding enlargement of weight, the outer diameter is substantially 50 mm or more and 2000 mm or less. Is the diameter. In the case where the mold roll 2 is used instead of the back roll 3, a flat surface can be accurately formed on the convex portions on both sides of the film by using the smooth roll 4 instead of the back roll 5.

  The obtained convex flat film generally has a total area of the flat surface 7 of 10 to 90% with respect to the entire irregularity-formed surface, and is 20 to 20 from the viewpoint of improving the smoothness of the flat surface and suppressing the collapse of the convex part. 80% is preferable. The entire concavo-convex forming surface means the total area of the concavo-convex forming surface. If embossing or knurling is performed on the both ends in the width direction of the film for the purpose of preventing misalignment during winding, the processing area It shall mean the total area of the unevenness forming surface excluding.

  As for a convex part flat film, convex part height (H in FIG. 2 (B)) is 10-90% normally with respect to the convex part height (FIG. 2 (A), h) before flat surface formation. From the viewpoint of improving the smoothness of the flat surface and suppressing the collapse of the convex portion, it is preferably 20 to 80%. The convex portion height H is preferably 0.05 to 50 μm. By setting the height of the convex portion within the above range, it can be used as a prism sheet, a lens sheet, a diffraction grating, or a non-reflective structure.

The thickness of the convex flat film (in FIG. 2B, T ₂ ) is not particularly limited as long as the object of the present invention is achieved, and is usually 8 to 190 μm, preferably 20 to 140 μm.

  What is necessary is just to wind up with a winding roll, after obtaining a convex part flat film.

(Use)
The convex flat film produced by the above method is particularly suitable for use as an optical film, for example, a prism sheet, a lens sheet, a diffraction grating, a non-reflective structure or the like.

  For example, when using a convex flat film as a prism sheet, it is preferably used as a brightness enhancement film for a backlight for liquid crystal displays.

  For example, when using a convex flat film as a nonreflective structure, it is preferably used as an antireflection film on the outermost surface of the display.

[Production of cellulose ester film]
440 parts by weight of methylene chloride and 35 parts by weight of ethanol were put into a closed container, and while stirring, 100 parts by weight of cellulose ester (acetyl group substitution degree 2.9, Mn = 160,000, Mw / Mn = 2.0), 5 parts by weight of methylolpropane tribenzoate, 5 parts by weight of ethylphthalylethylglycolate, 1 part by weight of Tinuvin 109 (manufactured by Ciba Specialty Chemicals), 1 part by weight of Tinuvin 171 (manufactured by Ciba Specialty Chemicals), And 0.3 part by weight of Aerosil R972V (manufactured by Nippon Aerosil Co., Ltd.) were sequentially added, and completely dissolved and mixed while heating and stirring. The fine particles were added dispersed in a part of the solvent. After the temperature was lowered to the temperature at which the solution was cast and allowed to stand overnight, a defoaming operation was performed, and then the solution was Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. Filtration using 244 gave a cellulose ester solution.

Next, the cellulose ester solution whose temperature was adjusted to 33 ° C. was fed to a die and uniformly cast from a die slit onto a stainless steel belt. The cast part of the stainless steel belt was heated from the back with hot water of 37 ° C. After casting, the dope film on the metal support (which will be referred to as the web after casting on the stainless steel belt) is dried by applying hot air of 44 ° C., and the residual solvent amount during peeling is 120% by mass. Then, the film was stretched so as to have a predetermined longitudinal stretching ratio by applying tension at the time of peeling, and then the web end was gripped by a tenter, and stretched to the stretching ratio shown in the table in the width direction. After stretching, holding for several seconds while maintaining its width, after releasing the tension in the width direction, releasing the width holding, and further transporting for 20 minutes in the third drying zone set at 125 ° C., Drying was performed to produce a cellulose ester film having a predetermined film thickness having a width of 1.4 to 2 m and a knurling having a width of 1.5 cm and a height of 8 μm at the end.
The produced cellulose ester film had a longitudinal draw ratio of 1.1 times, a transverse draw ratio of 1.1 times, a film thickness of 100 μm, a film forming width of 2000 mm, and a Tg of 160 ° C.

[Examples 1 to 14]
Using the apparatus shown in FIG. 1, the unevenness forming step and the convex portion correcting step were carried out while the cellulose ester film 1 was conveyed at a conveyance speed of 50 m / min. Specifically, in the heating chamber 10, a mold roll 2 (made of aluminum, diameter φ = 100 mm, roll length 1 = 2000 mm) and a back roll 3 whose surface is mirror-finished (made of aluminum, diameter φ = 100 mm, roll length 1 = 2000 mm). , With a surface roughness Ra = 15 nm), a one-dimensional prism shape with an apex angle of 90 °, a height of 10 μm, and a pitch of 20 μm as shown in FIG. An uneven pattern was formed (unevenness forming step). The convex part which the uneven | corrugated film has has a substantially triangular shape in the cross section perpendicular | vertical with respect to the width direction of a film, and was formed continuously in the width direction of the film. Subsequently, the smooth roll 4 (made of aluminum, diameter φ = 80 mm, roll length l = 2000 mm, surface roughness Ra = 15 nm) and the surface of the film 1 on which the uneven pattern is formed are mirror-finished. 2 and the back roll 5 (made of aluminum, diameter φ = 80 mm, roll length 1 = 2000 mm, surface roughness Ra = 15 nm), and flat on the top of the convex tip as shown in FIG. A surface was formed (convex portion correcting step) and wound up. In the convex portion correction step, the surface temperature (correction temperature) of the smooth roll 4, the load on the film (correction load), and the surface roughness were adjusted as shown in Table 1. The correction time was ^10-2 seconds.

[Comparative Example 1]
Except that the mold roll was changed to the one having the uneven shape shown below, the film surface temperature in the heating chamber and the load by the mold roll were changed as shown in Table 1, and the convex part correction step was not performed, A film was produced in the same manner as in Example 1.
The uneven shape of the mold roll was a shape in which the convex portions of the film had a trapezoidal shape in a cross section perpendicular to the width direction of the film and were continuous in the width direction of the film. Specifically, the trapezoidal convex portion of the film had a height of 5 μm, an upper base of 10 μm, and a lower base of 20 μm in a vertical section with respect to the width direction of the film, and the pitch was 20 μm.

[Evaluation method]
The AFM image of the uneven surface in the finally produced film was observed, and the following items were evaluated.

(Smoothness)
The surface roughness Ra of the flat surface at any 10 points was measured by AFM and evaluated based on the average value thereof.
○: The average value of Ra was 20 nm or less;
(Triangle | delta): The average value of Ra was 50 nm or less;
X: The average value of Ra was larger than 50 nm.

(Recessed crush)
As shown in FIG. 3, the size L of the recess crush 20 at the boundary between the flat surface and the upstream recess in the transport direction adjacent to the flat surface is measured at any 10 points, and based on the average value thereof. evaluated.
○: The average value of L was 50 nm or less;
Δ: The average value of L was 100 nm or less;
X: The average value of L was larger than 100 nm.

(Flat surface ratio)
The ratio of the total area of the flat surface formed at the tip of the convex portion to the entire uneven surface was determined from the AFM image. The said value is an average value about the AFM image in arbitrary 10 places.

(Convex height ratio)
The ratio of the convex portion height H after the flat surface formation as shown in FIG. 2 to the convex portion height h before the flat surface formation was obtained from the AFM image. The said value is an average value about the AFM image in arbitrary 10 places.

It is a schematic block diagram which shows one Embodiment of the apparatus which enforces the manufacturing method of the optical film of this invention. (A) is a schematic sectional drawing of the polymer film which shows an example of the uneven | corrugated shape before flat surface formation, (B) is a schematic sectional drawing of the polymer film which shows an example of the uneven | corrugated shape after flat surface formation. It is an expanded sectional view of the polymer film which shows an example of the uneven | corrugated shape after flat surface formation.

Explanation of symbols

  1: polymer film, 1a: first surface, 1b: second surface, 2: mold roll, 3: back roll, 4: smooth roll, 5: back roll, 20: crushing of recess.

Claims (5)

  The manufacturing method of the optical film characterized by having a convex part correction process which presses a smooth roll on the uneven | corrugated formation surface of the polymer film with which the unevenness | corrugation was formed on the surface, and forms a flat surface at the front-end | tip of a convex part.   2. The method for producing an optical film according to claim 1, wherein the total area of the flat surface formed at the tip of the convex portion is 20 to 80% with respect to the entire surface on which the unevenness is formed.   The method for producing an optical film according to claim 1 or 2, wherein the height of the convex portion after forming the flat surface is 20 to 80% of the height of the convex portion before forming the flat surface. The correction temperature in the convex part correction process is Tg-60 to Tg + 40 ° C. when the glass transition temperature of the polymer film is Tg,
The correction load when pressing the smooth roll against the uneven surface is 2 to 300 N / mm,
The surface roughness Ra of a smooth roll is 1-50 nm, The manufacturing method of the optical film in any one of Claims 1-3 characterized by the above-mentioned.   The method for producing an optical film according to any one of claims 1 to 4, wherein the maximum convex portion height after the flat surface is formed is 0.05 to 50 µm.

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