WO2012108209A1

WO2012108209A1 - Method for producing optical film

Info

Publication number: WO2012108209A1
Application number: PCT/JP2012/000893
Authority: WO
Inventors: 寛行大西
Original assignee: コニカミノルタオプト株式会社
Priority date: 2011-02-09
Filing date: 2012-02-09
Publication date: 2012-08-16
Also published as: JPWO2012108209A1

Abstract

The objective of the present invention is to provide a method that is for producing an optical film and whereby, in a step for performing embossing, when an embossing ring presses a substrate film, edge stretching of the embossed section does not arise, and black bands and blocking do not arise when the film is in a roll shape. Namely, the method for producing an optical film produced by using an embossing device, which is provided with an embossing back roller and an embossing roller having an imprinting ring, to press the embossing roller to an elongated film that is the substrate, and after performing embossing, rolling up the film, is characterized by the film production speed being at least 80 m/minute and the surface roughness (Ra) of the side surface of the imprinting ring being 10-20 μm.

Description

Manufacturing method of optical film

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

In recent years, various display devices such as a liquid crystal television, a plasma display (PDP), and an organic EL display have been developed in addition to a CRT, and their screen sizes are increasing. With an increase in screen size and image quality, an optical film on which an antireflection layer or the like is formed is attached to the front surface of a display device in order to improve visibility. Moreover, in such a display apparatus, a hand may touch directly or an object may contact, and it is easy to damage it. Therefore, in general, an optical film with a hard coat layer in which a hard coat layer is formed on a base film for preventing scratches and an antireflection layer or the like formed thereon is used.

As such an optical film for a display device, a wide film having a size of 1000 mm or more, and further 2000 mm or more has recently been required due to a large screen. In addition, a thin base film having a thickness of about 40 μm has been used for mobile phones and notebook computers. Therefore, a resin film such as cellulose ester is used as the base film, and a hard coat layer, an antireflection layer, an antifouling layer or an antiglare layer is formed thereon as an optical functional layer.

However, when the base film becomes wider for widening as described above, or when the thickness of the base film is reduced for thinning, the optical film after forming the optical functional layer In the stage of winding up, non-uniform portions of the roll tightening are likely to occur. This non-uniform winding of the roll also facilitates adhesion between the film surfaces (hereinafter referred to as blocking). A film fed out from a roll in which blocking occurs causes wrinkles, scratches, etc., and cannot be applied to a display device, resulting in a decrease in yield.

In order to prevent the deformation of the film in the wound state of the optical film, it is conventional to provide a portion that is bulkier than the film surface called knurling or embossing on both sides in the width direction of the film in order to prevent such a problem. More proposed.

For example, in Patent Document 1, an embossing roll having a tooth tip shape of 90 ° to 130 ° is used to press against the surface of the film end, and the film thickness at the film end is deformed to make the embossing process bulky. A way to do it has been proposed.

JP 11-262950 A

In the prior art, for example, when embossing is performed using the method of Patent Document 1, when the speed of winding the optical film is faster than before, or when the winding length of the optical film is made longer, The problem of the black band in the rolled state cannot be sufficiently suppressed. Especially in the case of an optical film, when the winding speed is 80 m / min or more, the embossed surface and the resin film are embossed. It has been newly found that the beard-like fibrous foreign matter described below is extremely deteriorated.

異物 Foreign matter adhering to the film surface is increased by embossing. This means that when the base film when embossing is separated from the embossing roll, the thermoplastic film is not well separated from the embossing roll and stretches in a state where it is locally adhered to the embossing roll, and the beard-like fibers This is due to the occurrence of a foreign material.

In addition, the occurrence of the fibrous foreign matter deteriorates the embossed surface and reduces the shape of the convex portion (hereinafter referred to as a rib) formed on the embossed surface.

The present invention has been made in view of the prior art, and the problem to be solved is that, in the step of embossing the base film, the end of the film does not stretch when the embossed stamp is pressed. Another object of the present invention is to provide a method for producing an optical film that does not generate a black band in a roll shape.

In order to solve the above-mentioned problems, the present inventors, in a high-speed optical film manufacturing method having a film-forming speed of 80 m / min or more, include an embossing ring imprinting ring provided in an embossing device used for the manufacturing. Attention was paid to the study. As a result, it was found that by polishing the surface of the engraved ring so as to be in a specific range, the end portion of the optical film does not occur, and no black band occurs when it is formed into a roll. It came to complete.

That is, the method for producing an optical film according to the present invention uses an embossing device having an embossing roll having an engraved ring and an embossing back roll, and presses the embossing roll against a long film serving as a substrate. A method of manufacturing an optical film manufactured by winding the film after processing, wherein the film forming speed is 80 m / min or more, and the surface roughness Ra of the side surface of the marking ring is 10 to 20 μm. It is characterized by being.

The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

It is a schematic diagram which shows the optical film manufactured by the manufacturing method of this invention. It is sectional drawing which cut | disconnected the convex part in the plane in the half of the height H of a convex part. It is a schematic diagram of an embossing process. It is a schematic side view of an embossing part. It is a flow sheet which shows typically a manufacturing device concerning one embodiment of a manufacturing method of the present invention.

Hereinafter, although the form for implementing this invention is demonstrated in detail, this invention is not limited to these.

(Optical film manufacturing method)
In the manufacturing method of the optical film according to the present embodiment, after the embossing roll is pressed against the long film serving as the base material using an embossing device provided with a marking ring and an embossing roll, An optical film produced by winding the film, characterized in that the film-forming speed is 80 m / min or more, and the surface roughness Ra of the side surface of the marking ring is 10 to 20 μm.

When the film forming speed is high, especially at 80 m / min or higher, the surface roughness Ra of the side surface of the marking ring is set to 10 to 20 μm, so that the edge elongation occurs when the embossing ring pushes the base film. Hard to do. In addition, it is possible to prevent the occurrence of so-called blocking caused by sticking of beards or the like, and the occurrence of black bands.

The step of embossing in the present invention is to form an uneven portion on the surface of the base film by pressing an embossing roll having uneven portions on the surface of the long film as the base material, It is the process of making it bulkier than the film surface.

In the method for producing an optical film of the present invention, the surface layer of the embossing roll at the time of production is at least carbide, nitride, carbon nitride, diamond-like carbon (hereinafter referred to as DLC), titanium carbonitride (hereinafter referred to as “carbonic nitride”). , Referred to as TiCN). By using these materials, it is possible to reduce the incidence of whiskers of fibrous foreign matter.

Moreover, in the manufacturing method of the optical film of this invention, when it has the process of apply | coating an optical functional layer to the elongate film used as a base material during the manufacturing process, the process of embossing apply | coats an optical functional layer It is preferable to apply before and after the step. By doing in this way, an optical function layer can be apply | coated uniformly. Further, it is possible to prevent the generation of foreign matters and black bands in the step of winding the optical film coated with the optical functional layer.

FIG. 1 (a) schematically shows a plan view of the optical film 1 of the present invention having an embossed portion. The embossed portion 12 is a portion of a plurality of irregularities (convex portions 13 and concave portions 14) that are bulkier than the surface of the optical film side end portion, and is formed in the longitudinal direction of the optical film 1.

An optical functional layer may be applied to the surface of the optical film 1, and in this case, the embossed portion 12 is formed higher than the surface of the uppermost layer of the optical functional layer. Further, when the optical functional layer is not applied, an embossed portion higher than the surface of the optical film 1 is formed. The shape of the unevenness is not particularly limited, and various patterns may be used, or a convex thick film portion may be formed.

FIG. 1 (b) shows a cross-sectional view in which a pair of irregularities (13, 14) among a plurality of irregularities of the formed embossed portion 12 is cut in the thickness direction of the optical film 1.

FIG. 2 is a cross-sectional view of the convex portion 13 of FIG. 1 cut along a plane (AA in FIG. 1) parallel to the surface of the optical film 1 and at half the height H of the convex portion 13. .

In the optical film of the present invention, the width W of the convex shape at the cross section is preferably 3 to 100 μm, and more preferably 10 to 30 μm. If the average width is smaller than 3 μm, the strength is insufficient, and if it is larger than 100 μm, a flare failure due to end elongation occurs.

Here, the average width W is determined by measuring the widths W1, W2, W3, and W4 of the central portion of each knitting of the cross-sectional shape of the convex portion 13 in FIG. If the cross-sectional shape is not a quadrangle as shown in FIG. 2, four points are measured at almost equal intervals, and the average value is calculated.

In addition, by setting the cross-sectional area S in the range of 2500 to 10000 μm ² , even if the winding speed is increased or the winding length is increased, the generation of a black band in a rolled state is suppressed. And an optical film with few wrinkles and scratches can be obtained.

The average height H (μm) from the surface of the convex film is preferably 1.0 to 20 μm, and more preferably 3 to 10 μm. If the average height H is less than 1.0 μm, the film interlayer height is insufficient, and if it is greater than 20 μm, winding tightening tends to occur.

The ratio S / H between the cross-sectional area S (μm ² ) and the average height H (μm) from the surface of the convex film is preferably 100 to 3000. By setting S / H within this range, the generation of a black band in a rolled state can be further suppressed, and an optical film with fewer wrinkles and scratches can be obtained. The average height H from the film surface was determined by measuring the height of the convex portion from the film surface at 10 places at approximately equal intervals and 3 rows in width, and taking the average value of 30 points in total.

Further, the ratio S / Y between the above-mentioned cross-sectional area S μm ² and the widest width Y μm of the recess (see FIG. 2) is preferably 10 to 300. By setting S / Y within this range, it is possible to further suppress the generation of a black band in a rolled state, and to obtain an optical film with fewer wrinkles and scratches. The widest width Y of the recess is a portion of the widest distance in the width of the recess for the cross-sectional view of FIG.

Further, it is preferable that 10 to 300 pieces / cm ² of a pair of irregularities are formed on the side end portion of the embossed film. By forming the pair of irregularities at 10 to 300 pieces / cm ^2, it is possible to further suppress the generation of black bands in a rolled state, and to obtain an optical film with fewer wrinkles and scratches.

As a method for producing the optical film of the present invention, in the step of embossing, a plurality of engraved rings are pressed against the surface of the side end portion of the film to form a plurality of concave and convex pairs. When the film is pressed against the film, the height of the convex portion formed by the film member pushed away by the marking ring is preferably set to a predetermined height depending on the pressure and processing temperature for pressing the marking ring.

Moreover, in the manufacturing method of the optical film of this invention, when it has the process of apply | coating an optical functional layer to the elongate film used as a base material, the process of embossing is before and after the process of apply | coating an optical functional layer. It is preferable to apply. By doing in this way, while being able to apply | coat an optical functional layer uniformly, generation | occurrence | production of a foreign material and a black band can also be prevented in the process of winding up the optical film which apply | coated the optical functional layer.

3A, an embossing roll 61 having a plurality of engraved rings 20 on a cylindrical flat surface 21 (also referred to as a flat portion), and the embossing roll 61 and the optical film 1 are disposed to face each other. It is the figure which showed typically the embossing process of embossing to the both ends of the optical film 1 with the embossing back roll 62. FIG.

FIG. 3B is an enlarged view of a forming portion for forming irregularities on the optical film by the marking ring 20. The marking ring 20 has a quadrangular pyramid shape in which the tip portion 20a has a flat surface. The engraved ring 20 is pressed against the surface of the film 1 with a gap to form the convex portion 13.

As the shape of the marking ring, a quadrangular pyramid having a flat surface on the upper surface (pressing surface) of the marking 61 is used as an example. However, a triangular pyramid, a conical shape, or a cylindrical shape may be used. May be.

FIG. 4 is a schematic view showing the embossing process of FIG. 3B from the side. A convex portion 13 having a width B and a height h is formed at the end in the width direction of the optical film 1. Here, the height h of the emboss refers to the height from the film surface to the convex portion formed by the emboss roll. The heating method of the embossing roll 61 is not specifically limited, A heating fluid can be flowed inside a roll, a halogen heater can be used, or it can heat by dielectric heat_generation | fever.

The emboss height h needs to be a predetermined height to prevent blocking and black bands. Therefore, in order to obtain a predetermined emboss height h, the surface temperature of the embossing roll 61 and the pressing pressure of the embossing roll are adjusted. However, due to the friction between the embossing roll and the marking ring, a short whisker-like fibrous foreign matter may be generated on the unevenness of the embossed portion.

The size of the whisker-like fibrous foreign matter is about 1 to 100 μm in diameter and about 10 to 1000 μm in length, and when the width B is 2 cm, the number of generated is about 1 to 50 per embossed unevenness. appear. When the embossing roll 61 moves away from the film during embossing, the whiskers cause whisker-like fibrous foreign matter due to local expansion of the thermoplastic optical film 1. When the film forming speed is high, particularly when the film forming speed is 80 m / min or more, the whisker-like fibrous foreign matter makes the embossed height non-uniform, and a black band is generated when it is made into a roll shape or is detached from the embossed part. As a result, it is possible that the foreign matter adheres to the film.

Therefore, by polishing the side surface of the marking ring in the embossing roll, it is possible to prevent the generation of whiskers even when the film forming speed is high. The surface roughness Ra of the side surface of the marking ring is 10 to 20 μm, and preferably 13 to 17 μm. If Ra is less than 10 μm, end portion elongation tends to occur, and if it is larger than 20 μm, whiskers are likely to occur.

Furthermore, if the upper surface of the engraved ring in the embossing roll is polished, the generation of whiskers can be further prevented. The surface roughness Ra of the upper surface of the marking ring is 10 to 20 μm, preferably 13 to 17 μm. If Ra is less than 10 μm, it is difficult to polish the ring surface, and the surface roughness below this does not affect the whisker, and if it is more than 20 μm, whiskers tend to occur.

The polishing method of the side and top surfaces of the marking ring is preferably polished using two or more selected from a wire brush, a blast treatment, and a vertical polishing machine. With respect to polishing, by using a blast processing apparatus, it is possible to perform polishing processing of minute uneven portions.

In addition, blasting can be applied to workpieces made of inorganic materials such as metals, glass and ceramics, synthetic resins such as plastics, other resins, wood, rocks, and other various materials. In addition, by spraying at a certain angle and speed, optimum polishing is possible even when the processed surface has a deformed portion.

Also, by making the surface temperature of the embossing roll Tg + 50 ° C. or higher and Tg + 150 ° C. or lower of the base film, generation of whiskers can be further prevented. Tg is the glass transition temperature. When the surface temperature of the embossing roll is lowered below Tg + 50 ° C., the embossing height cannot be obtained sufficiently. Further, when the surface temperature of the embossing roll is raised above Tg, a whisker occurs on the unevenness of the embossed portion.

Furthermore, when the embossed portion is formed, the heat of the engraved ring in the emboss roll causes heat transfer to the embossed back roll through the optical film, and end elongation such that the back surface of the optical film extends.

Therefore, by setting the surface temperature of the embossed back roll within the range of 10 to 50 ° C., the end elongation can be prevented, and it is more preferably 20 ° C. or higher and 40 ° C. or lower. If the surface temperature of the embossed back roll is lowered below 10 ° C., the embossing processability is deteriorated. Further, when the surface temperature of the embossing roll is raised above 50 ° C., end elongation occurs.

The width B of the embossed portion according to the present invention is not particularly limited, but is 5 to 30 mm, preferably 10 to 25 mm, particularly preferably 15 to 20 mm. As for the location of the embossed portion, either the inside or outside of the width for applying the optical functional layer may be used. The position of the embossed portion is not particularly limited, but it is preferable that embossing is applied to a portion of 0 to 30 mm from the end in the width direction of the optical film. Moreover, when using the wide optical film like this invention, it is preferable to provide the said embossing part not only in the optical film edge part but in the inner side. That is, it is also preferable to provide a plurality of embossed portions on the optical film.

Further, the embossed portion according to the present invention may be formed on at least one surface of the film, or may be formed on both surfaces.

In the present invention, in order to improve the uniformity from the winding core side (at the beginning of winding of the film) to the center of winding to the outside of the winding (at the end of winding of the film) when the optical film is rolled up, The height of the embossed portion on the core side is higher than the height of the embossed portion on the outside of the winding, and the difference in height is preferably in the range of 10 to 20 μm, more preferably in the range of 3 to 8 μm.

For example, by changing the pressing pressure or temperature of the embossing roll so as to be a combination of the core-side embossing height (15 μm) / winding center embossing height (10 μm) / winding outer embossing height (5 μm), etc. By doing so, even if the embossed portion is pressed by the winding pressure in the winding core side direction, a desired height of the embossing can be ensured.

The winding pressure in the direction of the core when the optical film is rolled up is 2.0 to 5.0 MPa when the winding length is 3,900 m to 9,000 m. When the winding pressure in the above range is applied to the optical film, the average height H of the convex portions from the film surface is preferably 0.1 to 3 μm, and more preferably 0.5 to 2.0 μm. If it is smaller than 0.1 μm, the film interlayer height is low, and sticking failure is likely to occur. If it is larger than 3 μm, winding tightening will occur.

The standard deviation of the average height H when the above winding pressure is applied to the optical film is preferably 0.1 to 2.0 μm. When the standard deviation is smaller than 0.1 μm, embossing accuracy is practically difficult and workability is difficult, and when it is larger than 2.0 μm, the difference in right and left diameters of the original winding becomes large, causing the loosening of the winding. It becomes.

Also, the elongation of the embossed part is preferably in the range of 0.1 to 0.5%. When the elongation is smaller than 0.1%, the embossing range is narrowed and rib formation becomes insufficient. When the elongation is larger than 0.5%, workability in subsequent processes such as coating is deteriorated.

As the winding core when winding the optical film having these embossed portions or the optical film embossed before and after the optical functional layer is coated in a roll shape, any core can be used. However, the plastic material is preferably a hollow plastic core, and the plastic material may be any heat-resistant plastic that can withstand the heat treatment temperature. For example, phenol resin, xylene Examples thereof include resins such as resins, melamine resins, polyester resins, and epoxy resins. A thermosetting resin reinforced with a filler such as glass fiber is preferable.

In addition, the method for producing an optical film of the present invention is formed after a step of forming a resin, which is a raw material for a long optical film serving as a substrate, by a solution casting film forming method or a melt extrusion film forming method. It is preferable to perform an embossing process on the resulting film and then perform a winding process. Furthermore, the application of the optical functional layer is preferably performed during the period from the film forming process of the optical film serving as the substrate to the winding process. By doing in this way, the process to wind up can be performed at once and the roll-shaped optical film which suppressed generation | occurrence | production of the black band more can be manufactured.

FIG. 5 shows an embodiment of an optical film manufacturing apparatus using the optical film manufacturing method according to the present invention, but the present invention is not limited to this.

A preliminarily prepared thermoplastic resin solution is cast on a casting belt 8 from a die 7 to form a web (a film containing a residual solvent after casting a dope on a metal support is called a web). After peeling, the web is stretched by the tenter 9 and dried by the film drying apparatus 10. The stretched web forms an embossed portion on the web by an embossing roll 61 having irregularities formed on the surface and an embossing back roll 62 facing the embossing roll 61. Thereafter, the film on which the embossed portion is formed is wound up by the winding roll 11.

In FIG. 5, the embossing roll 61 and the embossing back roll 62 are installed behind the film drying apparatus 10, but any of the winding rolls 11 after the web is peeled off from the casting belt 8 can be used. You may install in the place. That is, the embossed film may be dried by the drying device 10. Moreover, when apply | coating an optical function layer, after applying the optical function layer after the film drying apparatus 10, after drying the optical function layer, it should just wind with the winding roll 11. FIG.

When the optical functional layer is applied in multiple layers, after the optical functional layer is dried, the next optical functional layer is applied and dried, and this process is repeated many times to form a multilayer optical functional layer. Then, the winding roll 11 may be wound. Further, after the optical functional layer is formed, the embossed portion may be formed in front of the take-up roll 11.

(Base film)
The film used as the base material that can be used in the present invention (when the optical functional layer is not applied, the base film becomes an optical film) will be described.

As the base film used in the present invention, it is preferable that it is easy to manufacture, has good adhesion to the optical functional layer, is optically isotropic, is optically transparent, and the like. Listed as a requirement. Transparent means that the transmittance of visible light is 60% or more, preferably 80% or more, particularly preferably 90% or more.

The base film used in the present invention is at least one resin selected from cellulose ester resin, polyester resin, acrylic resin, polycarbonate resin, polyethersulfone resin, polyacrylate resin, norbornene resin, and acrylic styrene resin. preferable.

For example, cellulose ester film, polyester film, polycarbonate film, polyarylate film, polysulfone (including polyethersulfone) film, polyethylene terephthalate, polyethylene naphthalate polyester film, polyethylene film, polypropylene film, cellophane, Cellulose diacetate film, cellulose triacetate, cellulose acetate butyrate film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, polycarbonate film, cycloolefin polymer film (Arton (manufactured by JSR)) ZEONEX, ZEONEA Ltd.)), polymethyl pentene film, polyether ketone film, polyether ketone imide film, a polyamide film, a fluororesin film, a nylon film, polymethyl methacrylate film, acrylic film or a glass plate or the like. Among them, a cellulose triacetate film, a polycarbonate film, and a polysulfone (including polyethersulfone) film are preferable, and in the present invention, in particular, a cellulose ester film (for example, Konicattak product names KC8UX2MW, KC4UX2MW, KC8UY, KC4UY, KC5UN, KC12UR ( Konica Minolta Opto Co., Ltd.)) is preferably used from the viewpoints of production, cost, transparency, isotropy, adhesion and the like. These films may be films produced by melt casting film formation or films produced by solution casting film formation.

As the optical properties of the base film, those having a retardation Rt in the film thickness direction of 0 nm to 300 nm and a retardation Ro in the in-plane direction of 0 nm to 1000 nm are preferably used.

In the present invention, it is preferable to use a cellulose ester film as the substrate film. As the cellulose ester, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate are preferable. Among them, cellulose acetate butyrate, cellulose acetate phthalate, and cellulose acetate propionate are preferably used.

In particular, when the substitution degree of acetyl group is X and the substitution degree of propionyl group or butyryl group is Y, X and Y are active ray curable resin layers on a base film having a mixed fatty acid ester of cellulose in the following range And an optical film provided with an antireflection layer is preferably used.

2.3 ≦ X + Y ≦ 3.0
0.1 ≦ Y ≦ 1.2
In particular, 2.5 ≦ X + Y ≦ 2.85
It is preferable that 0.3 ≦ Y ≦ 1.2.

In the present invention, it is preferable to use a film containing an acrylic resin and a cellulose ester as the base film. By using a synthetic film containing these, a supple film is obtained.

The mass ratio of the acrylic resin and the cellulose ester is preferably 95: 5 to 30:70. When the mass ratio of the cellulose ester is less than 5% by mass, it becomes brittle, and when it is greater than 70% by mass, the properties of the acrylic resin cannot be sufficiently expressed.

The molecular weight of the acrylic resin is preferably 80000 or more, and the molecular weight of the cellulose ester is preferably 75000 or more. When the molecular weight of the acrylic resin is less than 80000, it becomes brittle, and when the molecular weight of the cellulose ester is less than 75000, it becomes brittle.

The total substitution degree (T) of the acyl group of the cellulose ester is preferably 2.0 to 3.0, and the substitution degree of the acyl group having 3 to 7 carbon atoms is 1.2 to 3.0. It is preferable. Beyond these ranges, the compatibility deteriorates.

When cellulose ester is used as the substrate film according to the present invention, the cellulose used as the raw material for the cellulose ester is not particularly limited, and examples thereof include cotton linters, wood pulp (derived from coniferous trees, derived from hardwoods), kenaf and the like. . Moreover, the cellulose ester 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 esters use an organic solvent such as acetic acid or an organic solvent such as methylene chloride, and It can be obtained by reacting with a cellulose raw material using 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 used in the present invention is obtained by mixing and reacting the amount of the acylating agent in accordance with the degree of substitution. In the cellulose ester, these acylating agents react with hydroxyl groups of cellulose molecules. 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).

As the cellulose ester used in the present invention, a mixed fatty acid ester of cellulose in which a propionate group or a butyrate group is bonded in addition to an acetyl group such as cellulose acetate propionate, cellulose acetate butyrate, or cellulose acetate propionate butyrate Are also preferably used. The butyryl group forming butyrate may be linear or branched.

Cellulose acetate propionate containing a propionate group as a substituent has excellent water resistance and is useful as a film for liquid crystal image display devices.

The method for measuring the substitution degree of the acyl group can be measured in accordance with the provisions of ASTM-D817-96.

The number average molecular weight of the cellulose ester is preferably 70000 to 250,000, since it has high mechanical strength when molded and an appropriate dope viscosity, and more preferably 80000 to 150,000.

These cellulose esters are pressurized by applying a cellulose ester solution (dope) generally called a solution casting film forming method onto, for example, an endless metal belt for infinite transport or a support for casting of a rotating metal drum. It is preferable to manufacture the dope from a die by casting (casting).

As the organic solvent used for preparing these dopes, it is preferable that the cellulose ester can be dissolved and has an appropriate boiling point. For example, methylene chloride, methyl acetate, ethyl acetate, amyl acetate, methyl acetoacetate, acetone, tetrahydrofuran 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, 1,3-difluoro-2 -Propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3 , 3,3-pentafluoro-1-propanol, nitroethane, 1,3-dimethyl-2-imidazolidinone, etc. Although it is Rukoto, organic halogen compounds such as methylene chloride, dioxolane derivatives, methyl acetate, ethyl acetate, acetone, methyl acetoacetate, and the like are preferable organic solvents (i.e., good solvent), and as.

Further, from the viewpoint of preventing foaming in the web when the solvent is dried from the web (dope film) formed on the casting support during film formation, the boiling point of the organic solvent used is 30-80. The boiling point of the good solvent described above is, for example, methylene chloride (boiling point 40.4 ° C.), methyl acetate (boiling point 56.32 ° C.), acetone (boiling point 56.3 ° C.), ethyl acetate (boiling point 76. 82 ° C.).

Among the good solvents described above, methylene chloride or methyl acetate having excellent solubility is preferably used.

In addition to the organic solvent, it is preferable to contain 0.1% by mass to 40% by mass of an alcohol having 1 to 4 carbon atoms. It is particularly preferable that the alcohol is contained at 5 to 30% by mass. After casting the dope described above onto a casting support, the solvent starts to evaporate and the alcohol ratio increases and the web (dope film) gels, making the web strong and peeling from the casting support. It is also used as a gelling solvent for facilitating the dissolution, and when these ratios are small, it also has a role of promoting dissolution of the cellulose ester of the non-chlorine organic solvent.

Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol and the like.

Of these solvents, ethanol is preferred because it has good dope stability, relatively low boiling point, good drying properties, and no toxicity. It is preferable to use a solvent containing 5% by mass to 30% by mass of ethanol with respect to 70% by mass to 95% by mass of methylene chloride. Methyl acetate can be used in place of methylene chloride. At this time, the dope may be prepared by a cooling dissolution method.

The cellulose ester film used in the present invention is preferably stretched at least in the width direction. In particular, when the residual solvent amount is 3% by mass to 40% by mass in the solution casting process, the cellulose ester film is 1.01 times to the width direction. The film is preferably stretched 1.5 times. More preferably, it is biaxially stretched in the width direction and the longitudinal direction, and when the residual solvent is 3% by mass to 40% by mass, 1.01 to 1.5 times in the width direction and the longitudinal direction, respectively. It is desirable to be stretched. By doing in this way, the light diffusable film excellent in planarity and light diffusibility can be obtained.

The residual solvent amount is represented by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is the mass of the web (cellulose ester film containing the solvent) at an arbitrary point in time, and N is the mass when the web of M is dried at 110 ° C. for 3 hours.

In the present invention, the biaxially stretched cellulose ester film preferably has a light transmittance of 90% or more, more preferably 93% or more.

After biaxially stretching the cellulose ester film, an embossed portion is formed on the film by an embossing roll having irregularities formed on the surface and an embossing roll facing the embossing roll.

In the present invention, the surface temperature of the embossing roll is preferably adjusted in relation to the melting point of the base film and the glass transition point. For example, the melting point of TAC (triacetyl cellulose) is 300 ° C., and the glass transition temperature is 107. Considering that the temperature is 0 ° C., the surface temperature of the embossing roll is preferably adjusted between 204 ° C. and 251 ° C.

By embossing under such conditions as described above, it is possible to remarkably improve the deterioration of the winding shape during storage of the long optical film in roll form.

The substrate film according to the present invention preferably has a thickness of 15 to 100 μm, more preferably 20 to 80 μm, and moisture permeability was measured according to JIS Z 0208 (25 ° C., 90% RH). The value is preferably 200 g / m ² · 24 hours or less, more preferably 10 to 180 g / m ² · 24 hours or less, and particularly preferably 160 g / m ² · 24 hours or less. In particular, it is preferable that the film thickness is 20 to 80 μm and the moisture permeability is within the above range.

The base film according to the present invention is used as a long film, and specifically has a thickness of about 500 m to 8000 m and is usually provided in a roll shape. In addition, from the viewpoint of further exerting the effect of the method for producing an optical film of the present invention, the width of the base film is preferably 1 to 4 m.

When a cellulose ester film is used for the optical film of the present invention, it is preferable to contain the following plasticizer. Examples of plasticizers include phosphate ester plasticizers, phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, glycolate plasticizers, citrate ester plasticizers, and polyesters. A plasticizer or the like can be preferably used.

For phosphate plasticizers, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. For phthalate ester plasticizers, diethyl phthalate, dimethoxy Ethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, diphenyl phthalate, dicyclohexyl phthalate, and other trimellitic plasticizers such as tributyl trimellitate, triphenyl trimellitate, triethyl For pyromellitic acid ester plasticizers such as trimellitate, tetrabutyl pyromellitate, tetrafluoro For glycolate plasticizers such as nilpyromellitate and tetraethylpyromellitate, triacetin, tributyrin, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate, etc., citrate plasticizers In this, triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-n-butyl citrate, acetyl tri-n- (2-ethylhexyl) citrate and the like can be preferably used. Examples of other carboxylic acid esters include trimethylolpropane tribenzoate, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters.

As the polyester plasticizer, a copolymer of a dibasic acid and a glycol such as an aliphatic dibasic acid, an alicyclic dibasic acid, or an aromatic dibasic acid can be used. The aliphatic dibasic acid is not particularly limited, and adipic acid, sebacic acid, phthalic acid, terephthalic acid, 1,4-cyclohexyl dicarboxylic acid and the like can be used. As the glycol, ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol and the like can be used. These dibasic acids and glycols may be used alone or in combination of two or more.

The amount of these plasticizers to be used is preferably 1% by mass to 20% by mass, particularly preferably 3% by mass to 13% by mass with respect to the cellulose ester in terms of film performance, processability and the like.

When using two kinds of plasticizers, the content is at least 1% by mass or more, preferably 2% by mass or more.

Moreover, an ultraviolet absorber is preferably used for the optical film of the present invention.

As the ultraviolet absorber, those which are excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less and have little absorption of visible light having a wavelength of 400 nm or more are preferably used from the viewpoint of good liquid crystal display properties.

Specific examples of the ultraviolet absorber preferably used in the present invention include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. However, it is not limited to these.

Examples of the benzotriazole-based ultraviolet absorbers include the following ultraviolet absorbers as specific examples, but the present invention is not limited thereto.

UV-1: 2- (2'-hydroxy-5'-methylphenyl) benzotriazole UV-2: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) benzotriazole UV-3 : 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole UV-4: 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl)- 5-Chlorobenzotriazole UV-5: 2- (2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole UV-6: 2,2-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol)
UV-7: 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole UV-8: 2- (2H-benzotriazol-2-yl) -6- (Linear and side chain dodecyl) -4-methylphenol (TINUVIN171, manufactured by Ciba)
UV-9: Octyl-3- [3-tert-butyl-4-hydroxy-5- (chloro-2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl- Mixture of 4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate (TINUVIN109, manufactured by Ciba)

Moreover, although the following specific examples are shown as a benzophenone type ultraviolet absorber, this invention is not limited to these.

UV-10: 2,4-dihydroxybenzophenone UV-11: 2,2'-dihydroxy-4-methoxybenzophenone UV-12: 2-hydroxy-4-methoxy-5-sulfobenzophenone UV-13: Bis (2-methoxy -4-hydroxy-5-benzoylphenylmethane)

As the ultraviolet absorber preferably used in the present invention, a benzotriazole-based ultraviolet absorber and a benzophenone-based ultraviolet absorber that are highly transparent and excellent in preventing the deterioration of the polarizing plate and the liquid crystal are preferable, and unnecessary coloring is less. A benzotriazole-based ultraviolet absorber is particularly preferably used.

Also, the ultraviolet absorber having a distribution coefficient of 9.2 or more described in JP-A No. 2001-187825 improves the surface quality of a long film and is excellent in coating properties. In particular, it is preferable to use an ultraviolet absorber having a distribution coefficient of 10.1 or more.

Further, the polymer ultraviolet absorbers described in the general formula (1) or general formula (2) described in JP-A-6-148430 and the general formulas (3), (6) and (7) of Japanese Patent Application No. 2000-156039 ( Alternatively, an ultraviolet absorbing polymer) is also preferably used. As a polymer ultraviolet absorber, PUVA-30M (manufactured by Otsuka Chemical Co., Ltd.) and the like are commercially available.

Further, in order to impart slipperiness to the cellulose ester film used in the present invention, fine particles similar to those described in the coating layer containing an actinic radiation curable resin can be used.

The primary average particle diameter of the fine particles added to the cellulose ester film used in the present invention is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm. These fine particles preferably form secondary particles having a particle size of 0.1 to 5 μm and are contained in the cellulose ester film, and the preferable average particle size is 0.1 to 2 μm, more preferably 0.2 to 0.6 μm. As a result, irregularities having a height of about 0.10 to 20 μm are formed on the film surface, thereby providing appropriate slipperiness to the film surface.

The primary average particle size of the fine particles used in the present invention is measured by observing particles with a transmission electron microscope (magnification 500,000 to 2,000,000 times), observing 100 particles, and using the average value, The average particle size was taken.

The apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200 g / liter, and particularly preferably 100 to 200 g / liter. A larger apparent specific gravity makes it possible to make a high-concentration dispersion, which improves haze and agglomerates, and is preferable when preparing a dope having a high solid content concentration as in the present invention. Are particularly preferably used.

Silicon dioxide fine particles having an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more are, for example, a mixture of vaporized silicon tetrachloride and hydrogen burned in air at 1000 to 1200 ° C. Can be obtained. For example, it is marketed with the brand name of Aerosil 200V and Aerosil R972V (above, Nippon Aerosil Co., Ltd. product), and can use them.

The apparent specific gravity described above is calculated by the following equation by taking a certain amount of silicon dioxide fine particles in a graduated cylinder, measuring the weight at this time.

Apparent specific gravity (g / liter) = mass of silicon dioxide (g) / volume of silicon dioxide (liter)

Examples of the method for preparing the fine particle dispersion used in the present invention include the following three types.

<< Preparation Method A >>
After stirring and mixing the solvent and fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. The fine particle dispersion is added to the dope solution and stirred.

<< Preparation Method B >>
After stirring and mixing the solvent and fine particles, dispersion is performed with a disperser. This is a fine particle dispersion. Separately, a small amount of cellulose triacetate is added to the solvent and dissolved by stirring. The fine particle dispersion is added to this and stirred. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.

<< Preparation Method C >>
Add a small amount of cellulose triacetate to the solvent and dissolve with stirring. Fine particles are added to this and dispersed by a disperser. This is a fine particle addition solution. The fine particle additive solution is sufficiently mixed with the dope solution using an in-line mixer.

Preparation method A is excellent in dispersibility of silicon dioxide fine particles, and preparation method C is excellent in that silicon dioxide fine particles are difficult to re-aggregate. Among them, the preparation method B described above is a preferable preparation method that is excellent in both dispersibility of the silicon dioxide fine particles and difficulty in reaggregation of the silicon dioxide fine particles.

《Distribution method》
The concentration of silicon dioxide when the silicon dioxide fine particles are mixed with a solvent and dispersed is preferably 5% by mass to 30% by mass, more preferably 10% by mass to 25% by mass, and most preferably 15% by mass to 20% by mass. A higher dispersion concentration is preferable because liquid turbidity with respect to the added amount tends to be low, and haze and aggregates are improved.

The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

The amount of silicon dioxide fine particles added to the cellulose ester is preferably 0.01 parts by mass to 5.0 parts by mass and more preferably 0.05 parts by mass to 1.0 part by mass with respect to 100 parts by mass of the cellulose ester. Preferably, 0.1 part by weight to 0.5 part by weight is most preferable. The larger the added amount, the better the dynamic friction coefficient, and the smaller the added amount, the less aggregates.

Disperser can be a normal disperser. Dispersers can be broadly divided into media dispersers and medialess dispersers. For dispersing silicon dioxide fine particles, a medialess disperser is preferred because of its low haze. Examples of the media disperser include a ball mill, a sand mill, and a dyno mill. Examples of the medialess disperser include an ultrasonic type, a centrifugal type, and a high pressure type. In the present invention, a high pressure disperser is preferable. The high pressure dispersion device is a device that creates special conditions such as high shear and high pressure by passing a composition in which fine particles and a solvent are mixed at high speed through a narrow tube. When processing with a high-pressure dispersion apparatus, for example, the maximum pressure condition inside the apparatus is preferably 9.807 MPa or more in a thin tube having a tube diameter of 1 to 2000 μm. More preferably, it is 19.613 MPa or more. Further, at that time, those having a maximum reaching speed of 100 m / second or more and those having a heat transfer speed of 420 kJ / hour or more are preferable.

Examples of the high-pressure dispersing apparatus include an ultra-high pressure homogenizer (trade name: Microfluidizer) manufactured by Microfluidics Corporation, or a nanomizer manufactured by Nanomizer, and other manton gorin type high-pressure dispersing apparatuses such as a homogenizer manufactured by Izumi Food Machinery. And UHN-01 manufactured by Sanwa Machinery Co., Ltd.

In addition, casting a dope containing fine particles so as to be in direct contact with the casting support is preferable because a film having high slip properties and low haze can be obtained.

In addition, after casting, the film is peeled off, dried and wound into a roll, and then the optical thin film layer according to the present invention is provided. Until processing or shipment, packaging is usually performed in order to protect the product from dirt, static electricity, and the like. The packaging material is not particularly limited as long as the above purpose can be achieved, but a material that does not hinder volatilization of the residual solvent from the film is preferable. Specific examples include polyethylene, polyester, polypropylene, nylon, polystyrene, paper, various non-woven fabrics, and the like. Those in which the fibers are mesh cloth are more preferably used.

The cellulose ester film used in the present invention may have a multilayer structure by a co-casting method using a plurality of dopes.

Co-casting is a sequential multilayer casting method in which two or three layers are configured through different dies, and a simultaneous multilayer casting method in which two or three slits are combined in a die having two or three slits. Any of the multilayer casting methods combining sequential multilayer casting and simultaneous multilayer casting may be used.

Further, the cellulose ester used in the present invention is preferably used as a support having a small amount of bright spot foreign matter when formed into a film. In the present invention, the bright spot foreign material is a structure in which two polarizing plates are arranged orthogonally (crossed Nicols), a cellulose ester film is arranged between them, and light from a light source is applied from one side to the other side. When the cellulose ester film is observed, the light from the light source appears to leak.

The polarizing plate used for the evaluation at this time is preferably composed of a protective film having no bright spot foreign matter, and preferably a glass plate is used for protecting the polarizer. The occurrence of bright spot foreign matter is considered to be one of the causes of unacetylated cellulose contained in the cellulose ester. As countermeasures, the use of cellulose ester with a small amount of unacetylated cellulose, It can be removed and reduced by filtering the dissolved dope solution. Further, the thinner the film thickness, the smaller the number of bright spot foreign matter per unit area, and the lower the content of cellulose ester contained in the film, the fewer bright spot foreign matter.

The bright spot foreign matter having a bright spot diameter of 0.01 mm or more is preferably 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, 50 pieces / cm ² or less, 30 pieces / cm. ² or less, preferably 10 pieces / cm ² or less, but it is particularly preferred that a 0.

Also, the bright spots of 0.005 mm to 0.01 mm are preferably 200 pieces / cm ² or less, more preferably 100 pieces / cm ² or less, 50 pieces / cm ² or less, 30 pieces / cm ² or less. The number is preferably 10 / cm ² or less, but particularly preferred is the case where the bright spot is zero. A thing with few also about a bright spot of 0.005 mm or less is preferable.

When removing bright spot foreign matter by filtration, it is preferable to filter the composition in which a plasticizer is added and mixed, rather than filtering a cellulose ester dissolved alone, because the bright spot foreign matter removal efficiency is high. As the filter medium, conventionally known materials such as glass fibers, cellulose fibers, filter paper, and fluororesins such as tetrafluoroethylene resin are preferably used, but ceramics, metals and the like are also preferably used. The absolute filtration accuracy is preferably 50 μm or less, more preferably 30 μm or less, and 10 μm or less, and particularly preferably 5 μm or less.

These can be used in combination as appropriate. The filter medium can be either a surface type or a depth type, but the depth type is preferably used because it is relatively less clogged.

Next, the optical functional layer coated on the base film according to the present invention will be described.

The optical functional layer of the present invention is preferably an antireflection layer provided on the hard coat layer.

The antireflection layer or other thin film of the present invention may be formed directly on the substrate film, but may be formed thereon via another layer.

In the present invention, examples of the coating layer (thin film forming side coating layer, optical functional layer) applied to the surface on the thin film forming side of the base film include a hard coat layer, an antiglare layer, an adhesive layer, an antistatic layer, and the like. A hard coat layer, an antiglare layer, and an antistatic layer are preferably applied, and in the case of the optical film of the present invention, in particular, in order to increase the surface hardness of the optical film, the “other layer” Is preferably provided. Further, a back coat layer may be provided on the side where the antireflection layer or other thin film is formed and on the side opposite to the base film.

Here, a hard coat layer used for an optical film will be described as a coating layer as an “other layer” useful for the present invention.

The hard coat layer is preferably a layer containing an ultraviolet curable compound (resin) that is cured by ultraviolet rays, and an antireflection film having excellent scratch resistance can be obtained.

The ultraviolet curable resin layer of the hard coat layer is preferably a resin layer formed by polymerizing a component containing an ethylenically unsaturated monomer. Here, the ultraviolet curable resin layer refers to a layer mainly composed of a resin which is cured through a crosslinking reaction or the like by irradiation with an active ray such as an electron beam in addition to ultraviolet rays. Typical examples of the ultraviolet curable resin include an ultraviolet curable resin and an electron beam curable resin, but a resin that is cured by irradiation with active rays other than ultraviolet rays and electron beams may be used. Examples of the ultraviolet curable resin include an ultraviolet curable acrylic urethane resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, and an ultraviolet curable epoxy resin. be able to.

In general, UV-curable acrylic urethane resins are obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer and further adding 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate (hereinafter referred to as acrylate, methacrylate). And can be easily obtained by reacting an acrylate monomer having a hydroxyl group such as 2-hydroxypropyl acrylate (see, for example, JP-A-59-151110).

UV curable polyester acrylate resins can be easily obtained by reacting polyester polyol with 2-hydroxyethyl acrylate and 2-hydroxy acrylate monomers (see, for example, JP-A-59-151112). .

Specific examples of ultraviolet curable epoxy acrylate resins include those obtained by reacting epoxy acrylate with an oligomer, a reactive diluent and a photoreaction initiator added thereto (for example, JP-A-1- No. 105738). As the photoinitiator, one or more kinds selected from benzoin derivatives, oxime ketone derivatives, benzophenone derivatives, thioxanthone derivatives and the like can be selected and used.

Specific examples of ultraviolet curable polyol acrylate resins include trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, alkyl-modified dipentaerythritol pentaacrylate. Etc.

These resins are usually used together with known photosensitizers. Moreover, the said photoinitiator can also be used as a photosensitizer. Specific examples include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and the like. Further, when using an epoxy acrylate photoreactive agent, a sensitizer such as n-butylamine, triethylamine, tri-n-butylphosphine can be used. The photoreaction initiator or photosensitizer contained in the ultraviolet curable resin composition excluding the solvent component that volatilizes after coating and drying can be added in an amount of usually 1 to 10% by mass of the composition, and 2.5 to 6 It is preferable that it is mass%.

Examples of the resin monomer may include general monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, vinyl acetate, benzyl acrylate, cyclohexyl acrylate, and styrene as monomers having one unsaturated double bond. Monomers having two or more unsaturated double bonds include ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-cyclohexane diacrylate, 1,4-cyclohexyldimethyl adiacrylate, and the above-mentioned trimethylolpropane. Examples thereof include triacrylate and pentaerythritol tetraacryl ester.

For example, as an ultraviolet curable resin, Adekaoptomer KR / BY series: KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (manufactured by Asahi Denka Kogyo Co., Ltd.) Or KOHEI Hard A-101-KK, A-101-WS, C-302, C-401-N, C-501, M-101, M-102, T-102, D-102, NS-101, FT -102Q8, MAG-1-P20, AG-106, M-101-C (from Guangei Chemical Industry Co., Ltd.), or Seika Beam PHC2210 (S), PHCX-9 (K-3), PHC2213, DP-10 , DP-20, DP-30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (above, large Manufactured by Seika Kogyo Co., Ltd.), or KRM7033, KRM7039, KRM7130, KRM7131, UVECRYL29201, UVECRYL29202 (above, Daicel UCB Corporation), or RC-5015, RC-5016, RC-5020, RC-5031, RC- 5100, RC-5102, RC-5120, RC-5122, RC-5152, RC-5171, RC-5180, RC-5181 (manufactured by Dainippon Ink & Chemicals, Inc.) or Aulex No. 340 clear (manufactured by China Paint Co., Ltd.), Sunrad H-601 (manufactured by Sanyo Chemical Industries, Ltd.), SP-1509, SP-1507 (manufactured by Showa Polymer Co., Ltd.), or RCC-15C (Grace Japan Co., Ltd.) (Manufactured by company), Aronix M-6100, M-8030, M-8060 (above, manufactured by Toagosei Co., Ltd.) or other commercially available products.

The UV curable resin layer can be applied by a known method. As the solvent for coating the ultraviolet curable resin layer, for example, it can be appropriately selected from hydrocarbons, alcohols, ketones, esters, glycol ethers, and other solvents, or a mixture thereof can be used. . Preferably, propylene glycol mono (alkyl group having 1 to 4 carbon atoms) alkyl ether, preferably propylene glycol mono (alkyl group having 1 to 4 carbon atoms) alkyl ether ester is 5% by mass or more, more preferably 5 to 80% by mass. The solvent contained above is used.

As a light source for forming a cured film layer by photocuring reaction of an ultraviolet curable resin, any light source that generates ultraviolet rays can be used. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. The irradiation conditions vary depending on individual lamps, but the amount of light irradiated may if 20 ~ 10000mJ / cm ² degrees, preferably 50 ~ 2000mJ / cm ^2. In the near ultraviolet region to the visible light region, it can be used by using a sensitizer having an absorption maximum in that region.

The UV curable resin composition is coated and dried and then irradiated with UV light from a light source. The irradiation time is preferably 0.5 seconds to 5 minutes, and 3 seconds to 2 from the curing efficiency and work efficiency of the UV curable resin. Minutes are more preferred.

It is preferable to add inorganic or organic fine particles to the cured film layer thus obtained in order to prevent black bands and to improve the scratch resistance. Examples of the inorganic fine particles include silicon oxide, titanium oxide, aluminum oxide, tin oxide, zinc oxide, calcium carbonate, barium sulfate, talc, kaolin, calcium sulfate, and the like, and examples of the organic fine particles include polymethacrylic acid. Methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicon resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder Polyamide-based resin powder, polyimide-based resin powder, or polyfluorinated ethylene-based resin powder, and the like can be added to the ultraviolet curable resin composition. The average particle size of these fine particle powders is preferably 0.005 to 5 μm, more preferably 0.1 to 5.0 μm, and further preferably 0.1 to 4.0 μm added to the coating composition for forming the hard coat layer. It is particularly preferable from the viewpoint of the stability of the composition.

Desirably, the proportion of the ultraviolet curable resin composition and the fine particle powder is 0.1 to 30 parts by mass with respect to 100 parts by mass of the resin composition.

The layer formed by curing the ultraviolet curable resin formed in this way is a hard coat layer having a center line average roughness Ra of 1 to 50 nm as defined in JIS B 0601, but Ra is 0.1. It may be an antiglare layer of about 1 μm.

As a method for applying the hard coat layer, the antiglare layer, or the back coat layer to the substrate, a known method such as a gravure coater, a spinner coater, a wire bar coater, a roll coater, a reverse coater, an extrusion coater or an air doctor coater is used. be able to. The liquid film thickness (also referred to as wet film thickness) during coating is about 1 to 100 μm, preferably 0.1 to 30 μm, more preferably 0.5 to 30 μm. The dry film thickness is an average film thickness of 0.1 to 30 μm, preferably 1 to 20 μm.

(Back coat layer)
The base film used in the present invention is preferably provided with a back coat layer containing fine particles on the back side.

Examples of the fine particles contained in the backcoat layer useful in the present invention include fine particles of inorganic compounds or fine particles of organic compounds. The fine particles to be contained in the cellulose ester film, the particle diameter of the fine particles, and the apparent specific gravity of the fine particles. The dispersion method is almost the same.

The particles contained in the backcoat layer are 0.1 to 50% by weight, preferably 0.1 to 10% by weight, based on the binder. The larger the addition amount, the lower the dynamic friction coefficient, and the smaller the addition amount, the lower the haze and the fewer the aggregates. When the back coat layer is provided, the increase in haze is preferably 1% or less, particularly preferably 0 to 0.1%.

The organic solvent used in the back coat layer is not particularly limited, but since the anti-curl function can be imparted to the back coat layer, the organic solvent that dissolves the cellulose ester film and the resin of the cellulose ester film material or the organic solvent that swells. Solvents are useful. These may be appropriately selected depending on the curl degree of the cellulose ester film, the type of resin, the mixing ratio, the coating amount, and the like.

Examples of the organic solvent that can be used for the backcoat layer include benzene, toluene, xylene, dioxane, acetone, methyl ethyl ketone, N, N-dimethylformamide, methyl acetate, ethyl acetate, N-methylpyrrolidone, 1,3-dimethyl- 2-Imidazolidinone.

Examples of the organic solvent that is not dissolved include methanol, ethanol, n-propyl alcohol, i-propyl alcohol, and n-butanol, but the organic solvent is not particularly limited thereto.

As a coating method of the backcoat layer coating composition, a coating liquid film thickness (sometimes referred to as a wet film thickness) is 1 to 100 μm using a gravure coater, dip coater, wire bar coater, reverse coater, extrusion coater or the like. In particular, 5 to 30 μm is preferable.

The back coat layer can be applied in two or more steps. Further, the backcoat layer may also serve as an easy adhesion layer for improving the adhesion with the polarizer.

Examples of the resin used for the back coat layer include vinyl chloride / vinyl acetate copolymer, vinyl chloride resin, vinyl acetate resin, copolymer of vinyl acetate and vinyl alcohol, partially hydrolyzed vinyl chloride / vinyl acetate copolymer, and chloride. Vinyl homopolymers or copolymers such as vinyl / vinylidene chloride copolymer, vinyl chloride / acrylonitrile copolymer, ethylene / vinyl alcohol copolymer, chlorinated polyvinyl chloride, ethylene / vinyl chloride copolymer, ethylene / vinyl acetate copolymer, cellulose nitrate, cellulose acetate Cellulose ester resins such as propionate, cellulose diacetate, cellulose triacetate, cellulose acetate phthalate, cellulose acetate butyrate resin, maleic acid and / or Is a copolymer of acrylic acid, acrylic acid ester copolymer, acrylonitrile / styrene copolymer, chlorinated polyethylene, acrylonitrile / chlorinated polyethylene / styrene copolymer, methyl methacrylate / butadiene / styrene copolymer, acrylic resin, polyvinyl acetal resin, polyvinyl butyral resin, polyester polyurethane Resin, polyether polyurethane resin, polycarbonate polyurethane resin, polyester resin, polyether resin, polyamide resin, amino resin, styrene / butadiene resin, rubber resin such as butadiene / acrylonitrile resin, silicon resin, fluorine resin, polymethyl methacrylate , A copolymer of polymethyl methacrylate and polymethyl acrylate, etc. The present invention is not limited to these. Particularly preferred are cellulose resin layers such as cellulose diacetate and cellulose acetate propionate.

Next, the antireflection layer, which is the optical functional layer of the present invention, and the optical film coated therewith will be described.

In the method for producing an optical film of the present invention, at least one of a metal oxide layer, a metal oxynitride, a metal nitride, an organic polymer, and a liquid crystal compound is formed on the aforementioned base film, It is preferable to do. The antireflection layer may be formed directly on the base film, but at least one hard coat layer or other coating layer may be provided and formed on the base film having an uneven surface. This is a preferred method because it is less likely to be scratched in the process of handling the optical film and the step of making the optical film into a polarizing plate to be described later. As the other coating layer, the above-mentioned cured resin layer having a center line average surface roughness (Ra) defined by JIS B 0601 of 0.01 to 1 μm is preferable. These are actinic radiation curable resin layers that are cured by actinic radiation such as ultraviolet rays. An optical film excellent in scratch resistance can be obtained by forming the metal oxide layer according to the present invention on the resin layer cured by such ultraviolet rays.

In general, an antireflection layer of an optical film is formed by laminating a high refractive index layer having a refractive index higher than that of the base film and a low refractive index layer having a refractive index lower than that of the base film on the base film. Those laminated in the order of refractive index layer / low refractive index layer are preferably used from the viewpoint of reducing the reflectance.

Note that the present invention is not limited only to lamination in this order, and may be reversed, or a medium refractive index layer having a refractive index higher than that of the base film and lower than that of the high refractive index layer during this period. The present invention can also be achieved with a configuration of three or more layers sandwiching.

A metal oxide layer particularly preferably used as an example of the antireflection layer of the present invention will be described.

The metal oxide layer is preferably used as at least one of a high refractive index layer and a low refractive index layer.

There are methods for providing a metal oxide layer, such as coating, atmospheric pressure plasma CVD, sputtering, and vapor deposition. In the present invention, the antireflection layer is preferably formed by coating.

A method for forming a metal oxide layer by coating will be described.

The basic configuration of the optical film of the present invention will be described. The base film, the high refractive index layer, and the low refractive index layer preferably have a refractive index that satisfies the following relationship.

Refractive index of low refractive index layer <refractive index of base film <refractive index of hard coat layer <refractive index of high refractive index layer

In the present invention, it is also preferable to provide an optical film provided with an antiglare antireflection layer by imparting irregularities to the hard coat layer or the high refractive index layer.

In addition, a layer structure in the order of a base film, a hard coat layer (antiglare layer), a medium refractive index layer, a high refractive index layer, and a low refractive index layer is also a preferable configuration. It is preferable to impart an antiglare property to the low refractive index layer on the surface, and an antiglare layer may be provided on the surface.

(High refractive index layer)
In the present invention, in order to reduce the reflectance, a high refractive index layer having a refractive index higher than that of the base film is provided between the base film provided with the base film or the hard coat layer and the low refractive index layer. It is preferable to provide it. In addition, it is preferable to provide a middle refractive index layer between the base film and the high refractive index layer in order to reduce the reflectance. The refractive index of the high refractive index layer is preferably 1.55 to 2.30, and more preferably 1.57 to 2.20. The film thickness of the high refractive index layer is preferably 5 nm to 1 μm, more preferably 10 nm to 0.2 μm, and most preferably 30 nm to 0.2 μm from the characteristics of the optical interference layer. The haze of the high refractive index layer is preferably 5% or less, more preferably 3% or less, and most preferably 1% or less. The strength of the high refractive index layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more, with a pencil hardness of 1 kg load. The high refractive index layer preferably contains conductive particles, inorganic particles having a composition different from the conductive particles, and a binder. Either or both of the conductive particles and the inorganic particles may be used.

The conductive particles used for the high refractive index layer preferably have a refractive index of 1.60 to 2.60, and more preferably 1.65 to 2.50. The average particle diameter of the primary particles of the conductive particles is preferably 10 to 200 nm, more preferably 20 to 150 nm, and most preferably 30 to 100 nm. The average particle diameter of the conductive fine particles can also be measured from an electron micrograph taken with a scanning electron microscope (SEM) or the like. Further, it may be measured by a particle size distribution meter using a dynamic light confusion method or a static light confusion method. If the particle size is too small, aggregation tends to occur and the dispersibility deteriorates. If the particle size is too large, the haze is remarkably increased. The shape of the conductive particles is preferably a rice grain shape, a spherical shape, a cubic shape, a spindle shape, a needle shape, or an indefinite shape.

The amount of conductive particles used is preferably 5 to 85% by mass in the high refractive index layer. It is more preferably 10 to 80% by mass, and most preferably 20 to 75% by mass. If the amount used is small, desired effects such as refractive index and conductivity cannot be obtained, and if it is too large, film strength is deteriorated.

The conductive particles are supplied to a coating solution for forming a high refractive index layer in a dispersion state dispersed in a medium. As the dispersion medium for the inorganic fine particles, a liquid having a boiling point of 60 to 170 ° C. is preferably used. Specific examples of the dispersion solvent include water, alcohol (eg, methanol, ethanol, isopropanol, butanol, benzyl alcohol), ketone (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), ketone alcohol (eg, acetone alcohol) , Esters (eg, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate), aliphatic hydrocarbons (eg, hexane, cyclohexane), halogenated hydrocarbons (eg, methylene) Chloride, chloroform, carbon tetrachloride), aromatic hydrocarbons (eg, benzene, toluene, xylene), amides (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ethers (eg, diethyl ether, dioxane, Tiger hydrofuran), ether alcohols (e.g., 1-methoxy-2-propanol), propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate. Of these, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol and isopropanol are particularly preferable.

Further, the conductive particles can be dispersed in the medium using a disperser. Examples of the disperser include a sand grinder mill (eg, a bead mill with pins), a high-speed impeller mill, a pebble mill, a roller mill, an attritor, and a colloid mill. A sand grinder mill and a high-speed impeller mill are particularly preferred. Further, preliminary dispersion processing may be performed. Examples of the disperser used for the preliminary dispersion treatment include a ball mill, a three-roll mill, a kneader, and an extruder. It is also preferable to contain a dispersant.

Further, the high refractive index layer contains inorganic particles having a composition different from that of the conductive particles. The inorganic particles used are one kind of inorganic particles selected from the group consisting of hollow silica, colloidal silica, and magnesium fluoride.

The amount of the inorganic particles used is preferably 1 to 30% by mass in the high refractive index layer, more preferably 3 to 25% by mass, and most preferably 5 to 20% by mass. If the amount used is small, desired effects such as scratch resistance, adhesion, hardness, chemical resistance under high temperature and high humidity cannot be obtained, and if too large, film strength is deteriorated.

The high refractive index layer preferably uses a polymer having a crosslinked structure (hereinafter also referred to as a crosslinked polymer) as a binder polymer. Examples of the crosslinked polymer include polymers having a saturated hydrocarbon chain such as polyolefin (hereinafter collectively referred to as polyolefin), and crosslinked products such as polyether, polyurea, polyurethane, polyester, polyamine, polyamide, and melamine resin. Among them, a crosslinked product of polyolefin, polyether and polyurethane is preferred, a crosslinked product of polyolefin and polyether is more preferred, and a crosslinked product of polyolefin is most preferred. Further, it is further preferable that the crosslinked polymer has an anionic group. The anionic group has a function of maintaining the dispersion state of the inorganic fine particles, and the crosslinked structure has a function of imparting a film forming ability to the polymer and strengthening the film. The anionic group may be directly bonded to the polymer chain or may be bonded to the polymer chain via a linking group, but is bonded to the main chain as a side chain via the linking group. Is preferred.

Examples of the anionic group include a carboxylic acid group (carboxyl), a sulfonic acid group (sulfo), and a phosphoric acid group (phosphono). Of these, sulfonic acid groups and phosphoric acid groups are preferred. Here, the anionic group may be in a salt state. The cation that forms a salt with the anionic group is preferably an alkali metal ion. Moreover, the proton of the anionic group may be dissociated. The linking group that connects the anionic group and the polymer chain is preferably a divalent group selected from —CO—, —O—, an alkylene group, an arylene group, and combinations thereof. The crosslinked polymer which is a preferable binder polymer is preferably a copolymer having a repeating unit having an anionic group and a repeating unit having a crosslinked structure. In this case, the proportion of the repeating unit having an anionic group in the copolymer is preferably 2 to 96% by mass, more preferably 4 to 94% by mass, and most preferably 6 to 92% by mass. preferable. The repeating unit may have two or more anionic groups.

The crosslinked polymer having an anionic group may contain other repeating units (a repeating unit having neither an anionic group nor a crosslinked structure). Other repeating units are preferably a repeating unit having an amino group or a quaternary ammonium group and a repeating unit having a benzene ring. The amino group or quaternary ammonium group has a function of maintaining the dispersed state of the inorganic fine particles, like the anionic group. The benzene ring has a function of increasing the refractive index of the high refractive index layer. The amino group, the quaternary ammonium group, and the benzene ring can obtain the same effect even if they are contained in a repeating unit having an anionic group or a repeating unit having a crosslinked structure.

In the crosslinked polymer containing a repeating unit having an amino group or a quaternary ammonium group as a constituent unit, the amino group or quaternary ammonium group may be directly bonded to the polymer chain, or may be a side chain via a linking group. May be bonded to the polymer chain, but the latter is more preferred. The amino group or quaternary ammonium group is preferably a secondary amino group, a tertiary amino group or a quaternary ammonium group, more preferably a tertiary amino group or a quaternary ammonium group. The group bonded to the nitrogen atom of the secondary amino group, tertiary amino group or quaternary ammonium group is preferably an alkyl group, more preferably an alkyl group having 1 to 12 carbon atoms, still more preferably a carbon number. 1 to 6 alkyl groups. The counter ion of the quaternary ammonium group is preferably a halide ion. The linking group that connects the amino group or quaternary ammonium group to the polymer chain is a divalent group selected from —CO—, —NH—, —O—, an alkylene group, an arylene group, and combinations thereof. Is preferred. When the crosslinked polymer contains a repeating unit having an amino group or a quaternary ammonium group, the ratio is preferably 0.06 to 32% by mass, more preferably 0.08 to 30% by mass, Most preferably, the content is 0.1 to 28% by mass.

The cross-linked polymer is prepared by blending a monomer for generating a cross-linked polymer to prepare a coating solution for forming a high refractive index layer and a medium refractive index layer, and is generated by a polymerization reaction simultaneously with or after coating of the coating solution. Is preferred. Each layer is formed with the production of the crosslinked polymer. The monomer having an anionic group functions as a dispersant for inorganic fine particles in the coating solution. The monomer having an anionic group is preferably used in an amount of 1 to 50% by mass, more preferably 5 to 40% by mass, and still more preferably 10 to 30% by mass with respect to the inorganic fine particles. The monomer having an amino group or a quaternary ammonium group functions as a dispersion aid in the coating solution. The monomer having an amino group or a quaternary ammonium group is preferably used in an amount of 3 to 33% by mass based on the monomer having an anionic group. These monomers can be made to function effectively before application of the coating liquid by a method in which a crosslinked polymer is produced by a polymerization reaction simultaneously with or after application of the coating liquid.

Examples of monomers having two or more ethylenically unsaturated groups include esters of polyhydric alcohols and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, penta Erythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate , Pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene and its derivatives For example, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (for example, divinyl sulfone), acrylamide (for example, Methylene bisacrylamide) and methacrylamide. Commercially available monomers may be used as the monomer having an anionic group and the monomer having an amino group or a quaternary ammonium group. Examples of commercially available monomers having an anionic group include KAYAMAPMPM-21, PM-2 (manufactured by Nippon Kayaku Co., Ltd.), Antox MS-60, MS-2N, MS-NH4 (manufactured by Nippon Emulsifier Co., Ltd.). , Aronix M-5000, M-6000, M-8000 series (manufactured by Toagosei Chemical Industry Co., Ltd.), Biscote # 2000 series (manufactured by Osaka Organic Chemical Industry Co., Ltd.), New Frontier GX-8289 (Daiichi Kogyo Seiyaku NK ester CB-1, A-SA (manufactured by Shin-Nakamura Chemical Co., Ltd.), AR-100, MR-100, MR-200 (manufactured by Eighth Chemical Co., Ltd.), etc. It is done. Examples of commercially available monomers having a commercially available amino group or quaternary ammonium group include DMAA (manufactured by Osaka Organic Chemical Industry Co., Ltd.), DMAEA, DMAPAA (manufactured by Kojin Co., Ltd.), and Bremer QA (Nippon Yushi Co., Ltd.). And New Frontier C-1615 (Daiichi Kogyo Seiyaku Co., Ltd.).

The polymer polymerization reaction can be a photopolymerization reaction or a thermal polymerization reaction. A photopolymerization reaction is particularly preferable. A polymerization initiator is preferably used for the polymerization reaction. For example, the above-mentioned thermal polymerization initiator and photopolymerization initiator used for forming the binder polymer of the hard coat layer may be mentioned.

A commercially available polymerization initiator may be used as the polymerization initiator. In addition to the polymerization initiator, a polymerization accelerator may be used. The addition amount of the polymerization initiator and the polymerization accelerator is preferably in the range of 0.2 to 10% by mass of the total amount of monomers. The coating liquid (dispersion of inorganic fine particles containing monomer) may be heated to promote polymerization of the monomer (or oligomer). Moreover, it may heat after the photopolymerization reaction after application | coating, and may additionally process the thermosetting reaction of the formed polymer.

It is preferable to use a polymer having a relatively high refractive index for the high refractive index layer. Examples of the polymer having a high refractive index include polystyrene, styrene copolymer, polycarbonate, melamine resin, phenol resin, epoxy resin, and polyurethane obtained by reaction of cyclic (alicyclic or aromatic) isocyanate and polyol. . Polymers having other cyclic (aromatic, heterocyclic, and alicyclic) groups and polymers having halogen atoms other than fluorine as substituents can also be used with a high refractive index.

The metal oxide layer is preferably provided by coating a coating solution containing inorganic fine particles containing a metal oxide.

A high refractive index layer may be formed from an organometallic compound having film-forming ability.

It is preferable that the organometallic compound can be dispersed in an appropriate medium or is in a liquid state. Examples of organometallic compounds include metal alcoholates (eg, titanium tetraethoxide, titanium tetra-i-propoxide, titanium tetra-n-propoxide, titanium tetra-n-butoxide, titanium tetra-sec-butoxide, titanium Tetra-tert-butoxide, aluminum triethoxide, aluminum tri-i-propoxide, aluminum tributoxide, antimony triethoxide, antimony riboxide, zirconium tetraethoxide, zirconium tetra-i-propoxide, zirconium tetra-n- Propoxide, zirconium tetra-n-butoxide, zirconium tetra-sec-butoxide, zirconium tetra-tert-butoxide), chelate compounds (eg, di-isopropoxytitanium bi Acetylacetonate, di-butoxytitanium bisacetylacetonate, di-ethoxytitanium bisacetylacetonate, bisacetylacetone zirconium, aluminum acetylacetonate, aluminum di-n-butoxide monoethylacetoacetate, aluminum di-i-propoxide monomethyl Acetoacetate, tri-n-butoxide zirconium monoethyl acetoacetate), organic acid salts (for example, zirconyl ammonium carbonate), zirconium and the like.

(Low refractive index layer)
In the low refractive index layer of the optical film in the present invention, a layer lower than the refractive index of the base film is referred to as a low refractive index layer. Using a low-refractive-index layer formed by cross-linking of a fluorine-containing resin that is cross-linked by heat or ionizing radiation (hereinafter also referred to as “fluorinated resin before cross-linking”), a low-refractive index layer by a sol-gel method, and particles and a binder polymer A low refractive index layer having voids between or inside the particles is used. If the refractive index of the low refractive index layer is low, it is preferable because the antireflection performance is improved, but it is difficult from the viewpoint of imparting strength to the low refractive index layer. From this balance, the refractive index of the low refractive index layer is preferably in the range of 1.30 to 1.45. The film thickness of the low refractive index layer is preferably 5 nm to 0.5 μm, more preferably 30 nm to 0.2 μm, from the characteristics as an optical interference layer.

Preferred examples of the fluorine-containing resin before crosslinking include a fluorine-containing copolymer formed from a fluorine-containing vinyl monomer and a monomer for imparting a crosslinkable group. Specific examples of the fluorine-containing vinyl monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3 -Dioxoles, etc.), (meth) acrylic acid partial or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (Osaka Organic Chemical) or M-2020 (Daikin)), fully or partially fluorinated vinyl ethers, etc. Is mentioned. Examples of the monomer for imparting a crosslinkable group include glycidyl methacrylate, vinyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, vinylglycidyl ether, and other vinyl monomers having a crosslinkable functional group in advance in the molecule. , Vinyl monomers having a carboxyl group, hydroxyl group, amino group, sulfonic acid group, etc. (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyalkyl vinyl ether, hydroxyalkyl allyl) Ether, etc.). In the latter case, it is possible to introduce a crosslinked structure by adding a compound having a group that reacts with a functional group in the polymer and one or more reactive groups after copolymerization, as disclosed in JP-A-10-25388 and 10-147739. In the issue. Examples of the crosslinkable group include acryloyl, methacryloyl, isocyanate, epoxy, aziridine, oxazoline, aldehyde, carbonyl, hydrazine, carboxyl, methylol, and active methylene group. When the fluorine-containing copolymer is crosslinked by heating with a crosslinking group that reacts by heating, or a combination of an ethylenically unsaturated group and a thermal radical generator or an epoxy group and a thermal acid generator, it is a thermosetting type. In the case of crosslinking by irradiation with light (preferably ultraviolet rays, electron beams, etc.) by a combination of an ethylenically unsaturated group and a photo radical generator, or an epoxy group and a photo acid generator, the ionizing radiation curable type is used.

Further, in addition to the above monomers, a fluorine-containing copolymer formed by using a monomer other than the fluorine-containing vinyl monomer and the monomer for imparting a crosslinkable group may be used as the fluorine-containing resin before crosslinking. The monomer that can be used in combination is not particularly limited. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, 2-acrylic acid 2- Ethyl hexyl), methacrylic acid esters (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methyl styrene, etc.), vinyl ethers (methyl vinyl ether) Etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate, etc.), acrylamides (N-tertbutylacrylamide, N-cyclohexylacrylamide, etc.), methacrylamides, Ronitoriru derivatives and the like can be mentioned. In addition, it is also preferable to introduce a polyorganosiloxane skeleton or a perfluoropolyether skeleton into the fluorinated copolymer in order to impart slipperiness and antifouling properties. For example, polyorganosiloxane or perfluoropolyether having an acrylic group, methacrylic group, vinyl ether group, styryl group or the like at the terminal is polymerized with the above monomer, and polyorganosiloxane or perfluoropolyester having a radical generating group at the terminal. It can be obtained by polymerization of the above monomers with ether, reaction of a polyorganosiloxane or perfluoropolyether having a functional group with a fluorine-containing copolymer, or the like.

The proportion of each monomer used to form the fluorinated copolymer before cross-linking is preferably 20 to 70 mol%, more preferably 40 to 70 mol% of the fluorinated vinyl monomer, The amount of the monomer is preferably 1 to 20 mol%, more preferably 5 to 20 mol%, and the other monomer used in combination is preferably 10 to 70 mol%, more preferably 10 to 50 mol%.

The fluorine-containing copolymer can be obtained by polymerizing these monomers in the presence of a radical polymerization initiator by means of solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization or the like.

Fluorine-containing resin before crosslinking is commercially available and can be used. Examples of commercially available fluorine-containing resins before cross-linking include Cytop (Asahi Glass), Teflon (registered trademark) AF (DuPont), polyvinylidene fluoride, Lumiflon (Asahi Glass), Opstar (JSR), etc. Can be mentioned.

The low refractive index layer comprising a crosslinked fluorine-containing resin as a constituent component preferably has a dynamic friction coefficient in the range of 0.03 to 0.15 and a contact angle with water in the range of 90 to 120 degrees.

It is preferable from the point of strength improvement that the low refractive index layer containing a crosslinked fluorine-containing resin as a constituent component contains inorganic particles. As the inorganic fine particles used in the low refractive index layer, amorphous particles are preferably used, and are preferably composed of metal oxides, nitrides, sulfides or halides, and metal oxides are particularly preferable. As metal atoms, Na, K, Mg, Ca, Ba, Al, Zn, Fe, Cu, Ti, Sn, In, W, Y, Sb, Mn, Ga, V, Nb, Ta, Ag, Si, B Bi, Mo, Ce, Cd, Be, Pb and Ni are preferable, and Mg, Ca, B and Si are more preferable. Inorganic fine particles containing two or more metals may be used. Particularly preferred inorganic fine particles are silicon dioxide fine particles, that is, silica fine particles. The average particle size of the inorganic fine particles is preferably 0.001 to 0.2 μm, and more preferably 0.005 to 0.05 μm. The particle diameter of the fine particles is preferably as uniform (monodispersed) as possible. If the particle size of the inorganic fine particles is too large, light is scattered and the film becomes opaque. If the particle size is too small, the particles are likely to aggregate and difficult to synthesize and handle.

The compounding amount of the inorganic fine particles is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and particularly preferably 10 to 50% by mass with respect to the total mass of the low refractive index layer. The inorganic fine particles are preferably used after being subjected to a surface treatment. The surface treatment method includes physical surface treatment such as plasma discharge treatment and corona discharge treatment and chemical surface treatment using a coupling agent, but the use of a coupling agent is preferred. As the coupling agent, an organoalkoxy metal compound (eg, titanium coupling agent, silane coupling agent, etc.) is preferably used. When the inorganic fine particles are silica, treatment with a silane coupling agent described later is particularly effective.

Also, various sol-gel materials can be used as the material for the low refractive index layer. As such sol-gel materials, metal alcoholates (alcolates such as silane, titanium, aluminum, zirconium, etc.), organoalkoxy metal compounds and hydrolysates thereof can be used. In particular, alkoxysilane, organoalkoxysilane and its hydrolyzate are preferable. Examples of these include tetraalkoxysilane (tetramethoxysilane, tetraethoxysilane, etc.), alkyltrialkoxysilane (methyltrimethoxysilane, ethyltrimethoxysilane, etc.), aryltrialkoxysilane (phenyltrimethoxysilane, etc.), dialkyl. Examples thereof include dialkoxysilane and diaryl dialkoxysilane. In addition, organoalkoxysilanes having various functional groups (vinyl trialkoxysilane, methylvinyl dialkoxysilane, γ-glycidyloxypropyltrialkoxysilane, γ-glycidyloxypropylmethyl dialkoxysilane, β- (3,4-epoxy) Dicyclohexyl) ethyltrialkoxysilane, γ-methacryloyloxypropyltrialkoxysilane, γ-aminopropyltrialkoxysilane, γ-mercaptopropyltrialkoxysilane, γ-chloropropyltrialkoxysilane, etc.), perfluoroalkyl group-containing silane compounds ( For example, it is also preferable to use (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, etc.). In particular, the use of a fluorine-containing silane compound is preferable in terms of lowering the refractive index of the layer and imparting water and oil repellency.

As the low refractive index layer, it is also preferable to use a layer formed using microparticles between or within the fine particles using inorganic or organic fine particles. The average particle diameter of the fine particles is preferably from 0.5 to 200 nm, more preferably from 1 to 100 nm, still more preferably from 3 to 70 nm, and most preferably from 5 to 40 nm. The particle diameter of the fine particles is preferably as uniform (monodispersed) as possible.

The inorganic fine particles are preferably amorphous. The inorganic fine particles are preferably made of a metal oxide, nitride, sulfide or halide, more preferably a metal oxide or a metal halide, and most preferably a metal oxide or a metal fluoride. . As metal atoms, Na, K, Mg, Ca, Ba, Al, Zn, Fe, Cu, Ti, Sn, In, W, Y, Sb, Mn, Ga, V, Nb, Ta, Ag, Si, B Bi, Mo, Ce, Cd, Be, Pb and Ni are preferable, and Mg, Ca, B and Si are more preferable. An inorganic compound containing two kinds of metals may be used. A particularly preferred inorganic compound is silicon dioxide, ie silica.

The microvoids in the inorganic fine particles can be formed, for example, by crosslinking silica molecules forming the particles. Crosslinking silica molecules reduces the volume and makes the particles porous. (Porous) inorganic fine particles having microvoids are prepared by a sol-gel method (described in JP-A No. 53-112732 and Japanese Patent Publication No. 57-9051) or a precipitation method (described in APPLIED OPTICS, Vol. 27, page 3356 (1988)). Can be directly synthesized as a dispersion. Further, the powder obtained by the drying / precipitation method can be mechanically pulverized to obtain a dispersion. Commercially available porous inorganic fine particles (for example, silicon dioxide sol) may be used. The inorganic fine particles having microvoids are preferably used in a state of being dispersed in an appropriate medium in order to form a low refractive index layer. As the dispersion medium, water, alcohol (for example, methanol, ethanol, isopropyl alcohol) and ketone (for example, methyl ethyl ketone, methyl isobutyl ketone) are preferable.

The organic fine particles are also preferably amorphous. The organic fine particles are preferably polymer fine particles synthesized by polymerization reaction of monomers (for example, emulsion polymerization method). The organic fine particle polymer preferably contains a fluorine atom. The proportion of fluorine atoms in the polymer is preferably 35 to 80% by mass, and more preferably 45 to 75% by mass. It is also preferable to form microvoids in the organic fine particles by, for example, cross-linking the polymer forming the particles and reducing the volume. In order to crosslink the polymer forming the particles, it is preferable to use 20 mol% or more of the monomer for synthesizing the polymer as a polyfunctional monomer. The ratio of the polyfunctional monomer is more preferably 30 to 80 mol%, and most preferably 35 to 50 mol%. Examples of the monomer used for the synthesis of the organic fine particles include fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene) as examples of monomers containing fluorine atoms used to synthesize fluorine-containing polymers. Perfluoro-2,2-dimethyl-1,3-dioxole), fluorinated alkyl esters of acrylic acid or methacrylic acid, and fluorinated vinyl ethers. A copolymer of a monomer containing a fluorine atom and a monomer not containing a fluorine atom may be used. Examples of monomers that do not contain fluorine atoms include olefins (eg, ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride), acrylic esters (eg, methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate). , Methacrylic acid esters (for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate), styrenes (for example, styrene, vinyl toluene, α-methyl styrene), vinyl ethers (for example, methyl vinyl ether), vinyl esters ( Examples thereof include vinyl acetate and vinyl propionate), acrylamides (for example, N-tert-butylacrylamide, N-cyclohexylacrylamide), methacrylamides and acrylonitriles. Examples of polyfunctional monomers include dienes (eg, butadiene, pentadiene), esters of polyhydric alcohols and acrylic acid (eg, ethylene glycol diacrylate, 1,4-cyclohexane diacrylate, dipentaerythritol hexaacrylate), Esters of polyhydric alcohol and methacrylic acid (for example, ethylene glycol dimethacrylate, 1,2,4-cyclohexanetetramethacrylate, pentaerythritol tetramethacrylate), divinyl compounds (for example, divinylcyclohexane, 1,4-divinylbenzene), divinyl Examples include sulfones, bisacrylamides (eg, methylenebisacrylamide) and bismethacrylamides.

The micro voids between the particles can be formed by stacking at least two fine particles. When spherical particles having the same particle diameter (completely monodispersed) are closely packed, microvoids between particles with a porosity of 26% by volume are formed. When spherical fine particles having the same particle diameter are simply filled with cubic particles, microvoids between fine particles having a porosity of 48% by volume are formed. In an actual low-refractive index layer, the particle size distribution of fine particles and intra-particle microvoids exist, so the porosity varies considerably from the above theoretical value. When the porosity is increased, the refractive index of the low refractive index layer is lowered. When microvoids are formed by stacking fine particles, the size of the microvoids can be adjusted to an appropriate value (does not scatter light and cause no problem with the strength of the low refractive index layer) by adjusting the particle size of the fine particles. Can be adjusted. Furthermore, by making the particle diameters of the fine particles uniform, it is possible to obtain an optically uniform low refractive index layer in which the size of microvoids between particles is uniform. Thereby, although the low refractive index layer is microscopically a microvoided porous film, it can be optically or macroscopically uniform. The interparticle microvoids are preferably closed in the low refractive index layer by fine particles and a polymer. The closed air gap also has an advantage that light scattering on the surface of the low refractive index layer is less than that of an opening opened on the surface of the low refractive index layer.

By forming the microvoids, the macroscopic refractive index of the low refractive index layer becomes lower than the sum of the refractive indexes of the components constituting the low refractive index layer. The refractive index of the layer is the sum of the refractive indices per volume of the layer components. The refractive index of the constituent component of the low refractive index layer such as fine particles or polymer is larger than 1, whereas the refractive index of air is 1.00. Therefore, a low refractive index layer having a very low refractive index can be obtained by forming microvoids.

The low refractive index layer preferably contains 5 to 80% by mass of polymer. The polymer has a function of adhering fine particles and maintaining the structure of a low refractive index layer including voids. The amount of the polymer used is adjusted so that the strength of the low refractive index layer can be maintained without filling the voids. The amount of the polymer is preferably 10 to 30% by mass with respect to the total amount of the low refractive index layer. In order to adhere the fine particles with the polymer, (1) the polymer is bonded to the surface treatment agent of the fine particles, (2) the fine particles are used as a core, and a polymer shell is formed around the fine particles. It is preferable to use a polymer as the binder. The polymer to be bonded to the surface treatment agent (1) is preferably the shell polymer (2) or the binder polymer (3). The polymer (2) is preferably formed around the fine particles by a polymerization reaction before preparing the coating solution for the low refractive index layer. The polymer (3) is preferably formed by adding a monomer to the coating solution for the low refractive index layer and performing a polymerization reaction simultaneously with or after the coating of the low refractive index layer. It is preferable to carry out a combination of two or all of the above (1) to (3), and to carry out a combination of (1) and (3) or a combination of (1) to (3). Particularly preferred. (1) Surface treatment, (2) shell, and (3) binder will be described sequentially.

(1) Surface treatment It is preferable that the fine particles (particularly inorganic fine particles) are subjected to a surface treatment to improve the affinity with the polymer. The surface treatment can be classified into physical surface treatment such as plasma discharge treatment and corona discharge treatment, and chemical surface treatment using a coupling agent. It is preferable to carry out only chemical surface treatment or a combination of physical surface treatment and chemical surface treatment. As the coupling agent, an organoalkoxy metal compound (eg, titanium coupling agent, silane coupling agent) is preferably used. When the fine particles are made of silicon dioxide, surface treatment with a silane coupling agent can be carried out particularly effectively. Specific examples of the silane coupling agent include methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxysilane, methyltriacetoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane. Methoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltriacetoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-glycidyloxy Propyltriethoxysilane, γ- (β-glycidyloxyethoxy) propyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, Examples include N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane and β-cyanoethyltriethoxysilane.

Examples of silane coupling agents having a disubstituted alkyl group with respect to silicon include dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldiethoxysilane, and γ-glycidyloxypropylmethyldiethoxysilane. Γ-glycidyloxypropylmethyldimethoxysilane, γ-glycidyloxypropylphenyldiethoxysilane, γ-chloropropylmethyldiethoxysilane, dimethyldiacetoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldi Ethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropylmethyldiethoxysilane, γ-mercaptopropylmethyldimethyl Kishishiran, .gamma.-mercaptopropyl methyl diethoxy silane, .gamma.-aminopropyl methyl dimethoxy silane, .gamma.-aminopropyl methyl diethoxy silane, methyl vinyl dimethoxy silane, and methyl vinyl diethoxy silane.

Of these, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane having a double bond in the molecule. Γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropylmethyldiethoxy are those having a disubstituted alkyl group with respect to silicon. Silane, methylvinyldimethoxysilane and methylvinyldiethoxysilane are preferred, γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxy Particularly preferred are propyltrimethoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane and γ-methacryloyloxypropylmethyldiethoxysilane.

Two or more coupling agents may be used in combination. In addition to the silane coupling agents shown above, other silane couplings may be used. Other silane coupling agents include alkyl esters of orthosilicate (eg, methyl orthosilicate, ethyl orthosilicate, n-propyl orthosilicate, i-propyl orthosilicate, n-butyl orthosilicate, sec-butyl orthosilicate, orthosilicate). Acid t-butyl) and hydrolysates thereof. The surface treatment with the coupling agent can be carried out by adding the coupling agent to the dispersion of fine particles and leaving the dispersion at a temperature from room temperature to 60 ° C. for several hours to 10 days. In order to accelerate the surface treatment reaction, inorganic acids (for example, sulfuric acid, hydrochloric acid, nitric acid, chromic acid, hypochlorous acid, boric acid, orthosilicic acid, phosphoric acid, carbonic acid), organic acids (for example, acetic acid, polyacrylic acid, Benzenesulfonic acid, phenol, polyglutamic acid), or salts thereof (eg, metal salts, ammonium salts) may be added to the dispersion.

(2) The polymer forming the shell is preferably a polymer having a saturated hydrocarbon as the main chain. A polymer containing a fluorine atom in the main chain or side chain is preferred, and a polymer containing a fluorine atom in the side chain is more preferred. Polyacrylic acid esters or polymethacrylic acid esters are preferred, and esters of fluorine-substituted alcohols with polyacrylic acid or polymethacrylic acid are most preferred. The refractive index of the shell polymer decreases as the content of fluorine atoms in the polymer increases. In order to reduce the refractive index of the low refractive index layer, the shell polymer preferably contains 35 to 80% by mass of fluorine atoms, and more preferably contains 45 to 75% by mass of fluorine atoms. The polymer containing a fluorine atom is preferably synthesized by a polymerization reaction of an ethylenically unsaturated monomer containing a fluorine atom. Examples of ethylenically unsaturated monomers containing fluorine atoms include fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole), Mention may be made of esters of fluorinated vinyl ethers and fluorine-substituted alcohols with acrylic acid or methacrylic acid.

The polymer forming the shell may be a copolymer comprising a repeating unit containing a fluorine atom and a repeating unit not containing a fluorine atom. The repeating unit containing no fluorine atom is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer containing no fluorine atom. Examples of ethylenically unsaturated monomers that do not contain fluorine atoms include olefins (eg, ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride), acrylic esters (eg, methyl acrylate, ethyl acrylate, 2-acrylic acid 2- Ethyl hexyl), methacrylic acid esters (for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate), styrene and its derivatives (for example, styrene, divinylbenzene, vinyl toluene, α-methyl styrene), vinyl ether ( For example, methyl vinyl ether), vinyl esters (for example, vinyl acetate, vinyl propionate, vinyl cinnamate), acrylamide (for example, N-tertbutylacrylamide, N-cyclohexylacrylic) Amides), methacrylamide and acrylonitrile.

When the binder polymer (3) described later is used in combination, a crosslinkable functional group may be introduced into the shell polymer to chemically bond the shell polymer and the binder polymer by crosslinking. The shell polymer may have crystallinity. When the glass transition temperature (Tg) of the shell polymer is higher than the temperature at the time of forming the low refractive index layer, it is easy to maintain microvoids in the low refractive index layer. However, if Tg is higher than the temperature at which the low refractive index layer is formed, the fine particles are not fused, and the low refractive index layer may not be formed as a continuous layer (resulting in a decrease in strength). In that case, it is desirable to use a binder polymer (3) described later in combination, and form the low refractive index layer as a continuous layer with the binder polymer. By forming a polymer shell around the fine particles, core-shell fine particles are obtained. The core-shell fine particles preferably contain 5 to 90% by volume, more preferably 15 to 80% by volume of a core composed of inorganic fine particles. Two or more kinds of core-shell fine particles may be used in combination. Further, inorganic fine particles having no shell and core-shell particles may be used in combination.

(3) The binder binder polymer is preferably a polymer having a saturated hydrocarbon or polyether as the main chain, and more preferably a polymer having a saturated hydrocarbon as the main chain. The binder polymer is preferably crosslinked. The polymer having a saturated hydrocarbon as the main chain is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer. In order to obtain a crosslinked binder polymer, it is preferable to use a monomer having two or more ethylenically unsaturated groups.

Examples of monomers having two or more ethylenically unsaturated groups include esters of polyhydric alcohols and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, pentaerythritol). Tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, Pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene and its derivatives (Eg 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg divinyl sulfone), acrylamide (eg methylene bisacrylamide) and methacrylamide Is mentioned. The polymer having a polyether as the main chain is preferably synthesized by a ring-opening polymerization reaction of a polyfunctional epoxy compound.

In place of or in addition to the monomer having two or more ethylenically unsaturated groups, a crosslinked structure may be introduced into the binder polymer by a reaction of a crosslinkable group. Examples of crosslinkable functional groups include isocyanate groups, epoxy groups, aziridine groups, oxazoline groups, aldehyde groups, carbonyl groups, hydrazine groups, carboxyl groups, methylol groups, and active methylene groups. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane can also be used as a monomer for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. The cross-linking group is not limited to the above compound, and may be one that exhibits reactivity as a result of decomposition of the functional group.

The polymerization initiator used for the polymerization reaction and the crosslinking reaction of the binder polymer is a thermal polymerization initiator or a photopolymerization initiator, and the photopolymerization initiator is more preferable. Examples of photopolymerization initiators include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds , Fluoroamine compounds and aromatic sulfoniums. Examples of acetophenones include 2,2-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxydimethylphenyl ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-4-methylthio-2-morpholinopropiophenone and 2 -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone. Examples of benzoins include benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether. Examples of benzophenones include benzophenone, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone and p-chlorobenzophenone. Examples of phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

The binder polymer is preferably formed by adding a monomer to the coating solution for the low refractive index layer, and at the same time as or after coating the low refractive index layer, by a polymerization reaction (further crosslinking reaction if necessary). Even if a small amount of polymer (for example, polyvinyl alcohol, polyoxyethylene, polymethyl methacrylate, polymethyl acrylate, diacetyl cellulose, triacetyl cellulose, nitrocellulose, polyester, alkyd resin) is added to the coating solution for the low refractive index layer Good.

In addition to the above-described components (inorganic fine particles, polymer, dispersion medium, polymerization initiator, polymerization accelerator), each layer of the optical film or the coating solution thereof includes a polymerization inhibitor, a leveling agent, a thickener, a coloring inhibitor, an ultraviolet ray Absorbers, silane coupling agents, antistatic agents and adhesion promoters may be added. Each layer of the antireflection film is formed by coating by dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating or extrusion coating (US Pat. No. 2,681,294). Can do. Two or more layers may be applied simultaneously. For the method of simultaneous application, US Pat. Nos. 2,761,791, 2,941,898, 3,508,947, 3,526,528 and Yuji Harasaki, Coating Engineering, page 253, It is described in Asakura Shoten (1973).

As a winding method, a generally used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, etc., and these may be used properly.

The winding length of the present invention refers to the length of the optical film that has been wound into a roll after being embossed. The winding length of the optical film is preferably 500 to 8000 m. Here, if the winding length of the optical film is less than 500 m, the number of windings of the obtained optical film is too large, and it is difficult to cope with packaging, which is not preferable. On the other hand, when the winding length of the optical film exceeds 8000 m, blocking or the like increases, which is not preferable.

Hereinafter, the present invention will be specifically described by way of examples, but the embodiments of the present invention are not limited thereto.

(Examples 1 to 13, Comparative Examples 1 and 2)
A cellulose ester film having a length of 3900 m, a width of 1.4 m, and a film thickness of 40 μm was produced as follows. A back coat layer was provided on one side of the base film, a hard coat layer was provided on the side opposite to the back coat layer, and the following antireflection layer was then applied. Thereafter, an embossed portion as shown below was provided. From the formation of the substrate film to the formation of the antireflection layer, the film was not wound up, but continuously, and wound into a roll after forming the embossed portion. At this time, the base film had a melting point of 300 ° C. and a glass transition temperature of 107 ° C.

(Production of cellulose ester film)
<Preparation of dope>
Cellulose triacetate (acetyl group substitution degree 2.9)
100 parts by mass Triphenyl phosphate 10 parts by mass Biphenyl diphenyl phosphate 2 parts by mass Tinuvin 326 (manufactured by Ciba Japan Co., Ltd.) 0.5 parts by mass Aerosil R972V (manufactured by Nippon Aerosil Co., Ltd.) 0.2 parts by mass Methylene chloride 405 parts by mass Ethanol 45 parts by mass The above was put into a closed-type dissolution kettle, completely dissolved at 70 ° C. with stirring, and after cooling, Azumi Filter Paper No. Filtration using 244 gave Dope A. The prepared dope A was cast on a stainless steel belt. The solvent was evaporated on the stainless steel belt, and the web was peeled off from the stainless steel belt. The peeled web was introduced into a tenter dryer, both ends were gripped with clips and dried at 80 ° C. while being stretched 1.1 times in the width direction, and placed in a roll dryer having respective drying zones of 110 ° C. and then 125 ° C. Drying was terminated while being conveyed through a number of arranged rolls, and a cellulose ester film was prepared.

(Coating back coat layer)
The following backcoat layer coating composition was die-coated so as to have a wet film thickness of 13 μm, and dried at a drying temperature of 90 ° C. to coat a backcoat layer.

<Backcoat layer coating composition>
Acetone 30 parts by weight Ethyl acetate 45 parts by weight Isopropyl alcohol 10 parts by weight Diacetyl cellulose 0.5 parts by weight Ultrafine silica 2% acetone dispersion (Aerosil 200V, manufactured by Nippon Aerosil Co., Ltd.) 0.2 parts by weight

(Coating of hard coat layer)
The following hard coat layer coating composition is die coated on the surface opposite to the back coat layer, dried at 80 ° C. for 5 minutes, and then irradiated with 160 mJ / cm ² of ultraviolet rays, and the total dry film thickness with the following antireflection layer Was provided with a hard coat layer so as to be 5 μm, and a hard coat film was prepared.

<Hard coat layer coating composition>
Dipentaerythritol hexaacrylate 70 parts by weight Trimethylolpropane triacrylate 30 parts by weight Photoinitiator (Irgacure 184 (manufactured by Ciba Japan)) 4 parts by weight Ethyl acetate 150 parts by weight Propylene glycol monomethyl ether 150 parts by weight Silicon compound (BYK-307 (manufactured by Big Chemie Japan)) 0.4 parts by mass When the pencil hardness of the hard coat layer was measured, it showed a hardness of 3H and an abrasion resistance effect.

(Production of optical film)
An antireflection layer was formed on the hard coat film prepared above.

On the hard coat film, the following coating solution for a high refractive index layer is applied using a bar coater, dried at 60 ° C., then irradiated with ultraviolet rays to cure the coating layer, and a high refractive index layer (refractive index 1). .9) was formed. Furthermore, the following coating solution for a low refractive index layer was applied using a bar coater, dried at 60 ° C., then irradiated with ultraviolet rays to cure the coating layer, and the low refractive index layer (refractive index 1.45). ) To form an optical film.

<Preparation of high refractive index layer / low refractive index layer>
(Preparation of titanium dioxide dispersion)
Titanium dioxide (primary particle mass average particle diameter: 50 nm, refractive index: 2.70) 30 parts by mass, anionic diacrylate monomer (PM21, Nippon Kayaku Co., Ltd.) 4.5 parts by mass, cationic methacrylate monomer (DMAEA, manufactured by Kojin Co., Ltd.) 0.3 parts by mass and 65.2 parts by mass of methyl ethyl ketone were dispersed by a sand grinder to prepare a titanium dioxide dispersion.

(Preparation of coating solution for high refractive index layer)
In 1152.8 g of cyclohexanone and 37.2 g of methyl ethyl ketone, 0.06 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and 0.02 g of a photosensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) were dissolved. Furthermore, the ratio of the above titanium dioxide dispersion and the titanium dioxide dispersion of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.) is increased, and the refractive index of the high refractive index layer is increased. The amount was adjusted so as to be a ratio, and the mixture was stirred at room temperature for 30 minutes, and then filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a high refractive index layer. When this coating liquid was applied to a cellulose ester film and dried, and the refractive index after UV curing was measured, a high refractive index layer having a refractive index of 1.9 and a dry film thickness of 68 nm was obtained.

(Preparation of coating solution for low refractive index layer)
200 g of a methanol dispersion of silica fine particles having an average particle size of 15 nm (methanol silica sol, manufactured by Nissan Chemical Co., Ltd.), 3 g of a silane coupling agent (KBM-503, manufactured by Shin-Etsu Silicone Co., Ltd.) and 2 g of 0.1 mol / L hydrochloric acid In addition, the mixture was stirred at room temperature for 5 hours and then allowed to stand at room temperature for 3 days to prepare a dispersion of silica fine particles treated with silane coupling. To 35.04 g of the dispersion, 58.35 g of isopropyl alcohol and 39.34 g of diacetone alcohol were added. Further, 1.02 g of photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and 0.51 g of photosensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) in 772.85 g of isopropyl alcohol were added. Furthermore, 25.6 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.) was added and dissolved. 67.23 g of the resulting solution was added to the above dispersion, a mixture of isopropyl alcohol and diacetone alcohol. The mixture was stirred for 20 minutes at room temperature and filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a low refractive index layer. When this coating liquid was applied to a cellulose ester film and dried, and the refractive index after UV curing was measured, the refractive index was 1.45 and the dry film thickness was 100 nm.

<Production of embossed part>
An embossing roll with irregularities formed on the surface is heated and pressed against the optical film in which the hard coat layer / antireflection layer is coated on the cellulose ester film, and the width of the embossed film is 20 mm wide at both ends in the width direction of the optical film. An embossed part of 10 μm was prepared under the following conditions to obtain optical films of Examples 1 to 12 and Comparative Examples 1 to 4 shown in Table 1.

Embossing roll material: Carbon steel (S45C), quenching treatment Embossing roll surface layer: No processing, DLC layer 1 μm deposition, TiCN layer 1 μm deposition Embossing roll surface temperature: 200-260 ° C.

[Evaluation]
(Embossed part elongation rate evaluation method)
From the film, the embossed part and the non-embossed part are each cut by the same length in the longitudinal direction and the embossed width in the width direction.

The length of the embossed part is La, and the length of the unembossed part is Lb.

○: La / Lb <100.1%
Δ: 100.1% ≦ La / Lb <100.5%
×: La / Lb ≧ 100.5%

(Evaluation of black band)
The optical films of Examples 1 to 13 and Comparative Examples 1 and 2 produced by the above method were visually observed for the occurrence of black bands in the roll state, and when no black bands were observed, ○ Although it was not a problem, it was evaluated as Δ when slightly observed, and when the film was wrinkled or foreign due to the black band and became difficult to use as a product, it was rated as x.

The above evaluation results are shown in Table 1.

As is apparent from the results in Table 1, in Examples 1 to 13 where the surface roughness Ra of the side surface of the marking ring is 10 to 20 μm, there is no problem in the elongation ratio of the embossed portion, and the black band is also observed. Did not occur.

On the other hand, in Comparative Example 1 in which the surface roughness Ra of the side surface of the marking ring and the surface roughness Ra of the upper surface are smaller than 10 μm, the elongation percentage of the embossed portion is increased and the black band is also generated. This caused quality problems.

Comparative Example 2 is an example in which embossing was produced at a conventional low film-forming speed (60 n / min). In this case, since the film forming speed is low, even when the surface roughness Ra of the side surface of the marking ring is 10 μm or more and the surface roughness Ra of the upper surface is 10 μm or more, the elongation rate of the embossed part and the black band There was no problem.

This specification discloses various modes of technology as described above, and the main technologies are summarized below.

That is, the method for producing an optical film according to the present embodiment uses an embossing apparatus having an embossing roll having an engraved ring and an embossing back roll, and presses the embossing roll against a long film serving as a base material. A method for producing an optical film produced by winding the film after embossing, wherein the film-forming speed is 80 m / min or more, and the surface roughness Ra of the side surface of the marking ring is 10 to 10 It is characterized by being 20 μm.

According to such a configuration, the surface roughness Ra of the side surface of the marking ring is in the range of 10 to 20 μm even though the film forming speed is high. When the embossing roll pushes the base film in the embossing process, the volume of ribs formed on the processed surface increases and the base film is elongated in the longitudinal direction and the width direction. An optical film in which no end elongation occurs can be obtained.

In the method for producing an optical film, the surface roughness Ra of the upper surface of the marking ring is preferably 10 to 20 μm.

According to such a configuration, polishing on the upper surface of the marking ring also increases the friction with the base film resin on the upper surface in addition to the side surface of the marking ring described above. It is possible to obtain an optical film in which no occurrence occurs.

In the method for producing an optical film, it is preferable that the side surface and the upper surface of the marking ring are polished using two or more selected from a wire brush, a blast treatment, and a vertical polishing machine. With respect to polishing, by using a blast processing apparatus, it is possible to perform polishing processing of minute uneven portions.

Blasting can be applied to workpieces made of inorganic materials such as metals, glass and ceramics, synthetic resins such as plastics, other resins, wood, rocks, and other various materials, and with compressed fluid By spraying at a constant angle and speed, optimum polishing is possible even when the processed surface has a deformed portion.

According to such a configuration, a desired surface roughness can be more effectively imparted to the surface composed of the side surface and the upper surface of the marking ring, and according to the embossing device provided with this marking ring, the end portion An optical film in which no elongation occurs can be obtained.

In the method for producing an optical film, the surface temperature of the embossed back roll is preferably 10 to 50 ° C. or less.

According to such a configuration, by adjusting the temperature of the embossing roll provided in the embossing device to a low temperature, the heat transfer from the embossing ring surface can be suppressed, and the end elongation of the optical film can be suppressed.

In the optical film manufacturing method, it is preferable that the width of the rib shape of the optical film manufactured using the embossing apparatus is 3 to 100 μm.

According to such a configuration, generation of a black band can be suppressed when the optical film is rolled.

This application is based on Japanese Patent Application No. 2011-025846 filed on Feb. 9, 2011, the contents of which are included in the present application.

In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. It is interpreted that it is included in

Since the friction with the base film resin is increased by using the method of the optical film of the present invention manufactured by using an embossing apparatus having an engraved ring having a surface roughness Ra of 10 to 20 μm, embossing When the embossing ring pushes in the base film in the step of performing, no end elongation occurs and no black band in a roll shape occurs.

Claims

Using an embossing device equipped with an embossing roll having an engraved ring and an embossing back roll, the embossing roll is pressed against a long film as a base material, embossed, and then rolled to produce the film. A method for producing an optical film, comprising:
The film forming speed is 80 m / min or more,
A method for producing an optical film, wherein the surface roughness Ra of the side surface of the marking ring is 10 to 20 μm.
2. The method for producing an optical film according to claim 1, wherein the surface roughness Ra of the upper surface of the marking ring is 10 to 20 μm.
The method for producing an optical film according to claim 1 or 2, wherein the side surface and the upper surface of the marking ring are polished using two or more kinds selected from a wire brush, a blast treatment, and a vertical polishing machine.
The method for producing an optical film according to any one of claims 1 to 3, wherein a surface temperature of the embossed back roll is 10 to 50 ° C.
5. The method for producing an optical film according to claim 1, wherein the width of the convex shape of the optical film produced using the embossing apparatus is 3 to 100 μm.