JP5455146B2 - Optical film - Google Patents

Description

  The present invention relates to an optical film having antifouling properties. In particular, the present invention relates to an antiglare hard coat film having antifouling properties.

  Usually, information terminals such as automatic cash withdrawal and deposit equipment (ATM), cash dispenser (CD), vending machine, navigation device, security system terminal, personal computer, etc. have display screens such as displays, touch panels, and touch panel displays. It is installed.

  When the user uses these information terminals, the display screen is touched with a finger to perform an operation, and thus the display screen may be a fingerprint of a lipid component derived from a living body such as sebum (hereinafter simply referred to as “fingerprint”). ), Or even if fingerprints are attached, it is necessary to make it easy to wipe off. As a conventional technique for imparting such antifouling properties (such as fingerprints, dirt adhesion prevention, and dirt wiping ease), for example, the surface free energy of a film placed on the surface of a display screen is changed to fluorine atoms or siloxane. In addition, a method of lowering by using silicone or the like is disclosed (see Patent Documents 1, 2, and 3). On the other hand, the stain prevention film formed on the surface of the display screen by using a fatty acid ester is made oleophilic, and by increasing the surface free energy of the film, the stain is not noticeable even if fingerprint stains are attached, Alternatively, a method for making the dirt inconspicuous is also disclosed (see Patent Document 4).

  In addition, in various displays such as liquid crystal displays (LCD), plasma displays (PDP), cathode ray tubes (CRT), touch panels, etc., there is a drawback that external light and outside scenes are reflected on the display screen, making it difficult to see the displayed image. . In order to prevent this reflection, a technique for imparting antiglare properties by forming a cured film in which silica particles are blended with an ultraviolet curable resin on a film is disclosed (see Patent Document 5). The display screen of the information terminal is also desired to have antiglare properties in addition to antifouling properties.

Japanese Patent Laid-Open No. 2004-256736 JP 2007-219485 A JP 2002-174702 A JP 2004-114355 A Japanese Examined Patent Publication No. 63-40283

  However, although the films disclosed in Patent Documents 1 to 3 have oil repellency, the adhesion of fingerprints and the like can be suppressed to some extent, but the sebum components of fingerprints are droplets on the film surface, so that they are easily noticeable. At the same time, if it is wiped off, it is easy to wipe off, but if it adheres to the film when it is wiped off, it will be in the form of droplets or spheres, so that it will be easily noticeable and the antifouling property will not be sufficiently obtained.

Moreover, in the film using the fatty acid ester etc. which are disclosed by patent document 4, when many users touch a display screen with a finger and operate, initially, sebum components, such as the attached fingerprint, are a film. Although it is difficult to notice dirt due to diffusion on the film due to its oleophilic property, dirt such as fingerprints gradually becomes conspicuous, and it becomes necessary to wipe it off. However, since the fatty acid ester contained in the film and the sebum component of dirt such as fingerprints are structurally similar, it is difficult to wipe off, and the fatty acid ester is saponified by a basic substance (for example, sodium or potassium) in the atmosphere. This causes a problem that the film itself deteriorates. Moreover, since the leveling property and the coating property of the coating material to which the fatty acid ester is added are greatly lowered, there arises a problem that the generation of interference fringes due to coating unevenness cannot be suppressed. When the interference fringes are generated, the visibility of the display screen is remarkably deteriorated. Therefore, it is necessary to suppress the occurrence of the interference fringes as much as possible.

  In addition, in the technology for imparting antiglare properties disclosed in Patent Document 5, when the amount of silica particles is reduced, the specular gloss increases, so that the antiglare properties decrease and the glare increases. Visibility also decreases, and when the blending amount is increased, the haze increases, resulting in a problem that the screen becomes whitish and the resolution decreases.

Therefore, in view of the above-described conventional problems, the present invention is an excellent antifouling agent against fingerprints and the like due to biological lipid components such as sebum on the display screen even when the display screen is touched and operated. It is a first object of the present invention to provide an optical film that has the properties and suppresses the generation of interference fringes on the film. It is a second object of the present invention to provide an optical film having excellent antifouling properties and antiglare properties.

  Therefore, as a result of intensive studies to achieve such an object, the present inventors have found that in an optical film in which one or more resin layers are provided on a transparent film, the outermost resin layer (hereinafter simply referred to as “ It has been found that the above-mentioned problems can be solved by adding a cellulose ester to the “outermost layer”), and the present invention has been completed.

In particular, when the surface free energy of the optical film (according to the wetting tension test method defined in JIS-6768) is 31 mN / m or more, particularly excellent effects of the present invention are exhibited.
In the present invention, the cellulose ester is preferably cellulose acetate butyrate.

In the present invention, the weight average molecular weight Mw of the cellulose ester is preferably in the range of 15000-75000.
Moreover, in this invention, it is suitable as a compounding quantity of the said cellulose ester that the solid content of the cellulose ester with respect to solid content of all resin of outermost layer shall be the range of 2 to 8 weight%.

Further, in order to impart antiglare properties to the optical film of the present invention, it is preferable that the resin layer contains inorganic fine particles and / or organic fine particles.
The inorganic fine particles and / or organic fine particles preferably have a particle diameter in the range of 0.5 to 5 μm and an oil absorption of 200 ml / 100 g or less.

Moreover, it is preferable that the specific gravity of the said inorganic fine particle and / or organic fine particle is higher than the specific gravity of resin of the resin layer containing this inorganic fine particle and / or organic fine particle.
The refractive index difference between the inorganic fine particles and / or organic fine particles and the resin of the resin layer containing the inorganic fine particles and / or organic fine particles is preferably in the range of 0.03 to 0.1.
In addition, the optical film of the present invention can exhibit antiglare properties with a 60 ° specular gloss of 100 ° or less and a haze of 15% or less.

According to the present invention, even when many users touch and operate the display screen with their fingers, the display screen has excellent antifouling properties against the attachment of fingerprints or the like due to biological lipid components such as sebum on the display screen. And the optical film which suppressed generation | occurrence | production of the interference fringe by the coating unevenness of a film can be obtained.
Moreover, according to this invention, the optical film which has anti-glare property with the outstanding antifouling property can be obtained.

Hereinafter, the optical film of the present invention will be described in detail based on the embodiments.
The present invention is an optical film in which one or more resin layers are provided on at least one surface of a transparent film, wherein the outermost resin layer (outermost layer) contains a cellulose ester.
In the present invention, even when the display screen is operated by touching with a finger, the display screen has excellent prevention against adhesion of fingerprints or the like due to biological lipid components such as sebum, and film coating at the time of production The reason for exhibiting an excellent effect in suppressing the generation of interference fringes due to unevenness of work is presumed as follows according to the inventors' consideration.

  As described above, there is a method of increasing the surface free energy of the optical film in order to impart antifouling properties. In order to set the surface free energy of the optical film to, for example, 31 mN / m or more, as disclosed in JP-A-2001-353808 (Patent Document 4), the fatty acid ester or the aromatic ester is used as the outermost surface. There is a method of containing in the resin layer, or a method of not incorporating a fluorine atom-containing resin or additive that lowers the surface free energy, siloxane-based and silicone-based resins or additives, etc. into the outermost resin layer, In these methods, the leveling property and coating property of the coating material forming the outermost resin layer are greatly reduced, so that coating unevenness occurs during film coating, and interference fringes due to coating unevenness occur. . That is, in these methods, there is a problem that antifouling properties (high surface free energy) and suppression of generation of interference fringes (coating unevenness) cannot be achieved at the same time.

  On the other hand, in the present invention, by including a cellulose ester in the outermost layer, both excellent antifouling properties and suppression of occurrence of interference fringes can be achieved. Compared with the leveling agent (fluorine leveling agent, siloxane leveling agent, acrylic leveling agent, etc.) in which cellulose ester is conventionally used, the decrease in surface free energy is small and the leveling effect is imparted. It is assumed that this is because. In addition, while other leveling agents are unevenly distributed on the surface layer side of the resin layer, the cellulose ester is more compatible with the resin than other leveling agents, so it is uniformly present in the coating film. Therefore, it is excellent in the durability of the antifouling effect (function retention by repeated wiping). Furthermore, since cellulose ester has high transparency, even when inorganic fine particles or organic fine particles are blended in order to impart antiglare properties, the problem that the screen becomes whitish and the resolution decreases is suppressed. Moreover, the problem of film deterioration does not occur.

  As a transparent film used in the present invention, a cellulose film such as triacetyl cellulose, a polyester film such as polyethylene terephthalate, a polyolefin film such as polypropylene, a cycloolefin film, a polycarbonate film, a polyacrylic film, and a polyurethane film Examples thereof include, but are not limited to, films and polyether films.

  In the present invention, the thickness of the transparent film is not particularly limited, but is preferably 10 to 500 μm. In the antiglare hard coat film having antifouling property, it is preferably 10 to 200 μm.

  In the present invention, the adhesiveness (for example, JIS-) of a transparent film or an undercoat layer (thermosetting resin or ionizing radiation curable resin (resin that is cured by ultraviolet rays or electron beams)) provided on the transparent film and the resin layer. For the purpose of improving coating properties and coating properties, it is possible to perform discharge treatment such as glow discharge treatment, corona discharge treatment, and plasma discharge treatment on transparent films and undercoat layers. is there.

  In the present invention, the resin that forms the resin layer is not particularly limited as long as it is a thermosetting resin or an ionizing radiation curable resin (a resin that is cured by ultraviolet rays or electron beams), but from the viewpoint of heat resistance, ionizing radiation curing. A mold resin is preferred. In the present invention, examples of the thermosetting resin include phenol resin, melamine resin, epoxy resin, urea resin and the like. In addition, the ionizing radiation curable resin is not particularly limited as long as it is a transparent resin that is cured by irradiation with an electron beam or ultraviolet rays. For example, a urethane acrylate resin, a polyester acrylate resin, and It can be appropriately selected from epoxy acrylate resins and the like. Preferred examples of the ionizing radiation curable resin include those composed of an ultraviolet curable polyfunctional acrylate having two or more (meth) acryloyl groups in the molecule. Specific examples of the UV curable polyfunctional acrylate having two or more (meth) acryloyl groups in the molecule include neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and trimethylol. Polyol polyacrylates such as propane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol A diglycidyl Epoxys such as diacrylate of ether, diacrylate of neopentyl glycol diglycidyl ether, di (meth) acrylate of 1,6-hexanediol diglycidyl ether ( A) Polyester (meth) acrylate, polyhydric alcohol, polyisocyanate and hydroxyl group-containing (meta) which can be obtained by esterifying acrylate, polyhydric alcohol and polyhydric carboxylic acid and / or anhydride and acrylic acid ) Urethane (meth) acrylate obtained by reacting acrylate, polysiloxane poly (meth) acrylate, and the like.

  The above-mentioned UV-curable polyfunctional acrylate may be used alone or in combination of two or more, and the content thereof is preferably 50 to 95 based on the resin solid content in the resin layer coating material. % By weight. In addition to the polyfunctional (meth) acrylate, preferably 10% by weight or less of 2-hydroxy (meth) acrylate and 2-hydroxypropyl (meth) acrylate with respect to the resin solid content in the coating for the resin layer. Monofunctional acrylates such as glycidyl (meth) acrylate can also be added.

  Moreover, the polymerizable oligomer used in order to adjust hardness can be added to the resin layer in this invention. Examples of such oligomers include terminal (meth) acrylate polymethyl (meth) acrylate, terminal styryl poly (meth) acrylate, terminal (meth) acrylate polystyrene, terminal (meth) acrylate polyethylene glycol, terminal (meth) acrylate acrylonitrile-styrene copolymer. Macromonomers such as polymers and terminal (meth) acrylate styrene-methyl methacrylate copolymers can be mentioned, and the content thereof is preferably 5 to 50% by weight with respect to the resin solid content in the resin layer coating material. is there.

  When the resin layer is multilayered in the optical film of the present invention, considering the curl and hardness (for example, by the pencil method scratch hardness specified in JIS-K5600), adhesion, and a function as a primer to the substrate. It is preferable to select and use a resin for each layer as appropriate.

  Examples of the cellulose ester contained in the outermost layer in the optical film of the present invention include cellulose acetate (CA), cellulose acetate butyrate (CAB), and cellulose acetate propionate (CAP). Among these, it is preferable to select cellulose acetate butyrate having an excellent leveling property improving effect.

  In the present invention, it is preferable to use a cellulose ester having a weight average molecular weight Mw in the range of 15000 to 75000. By setting the weight average molecular weight Mw to 75000 or less, it is possible to suppress an increase in the viscosity of the paint that forms the resin layer that causes interference fringes. On the other hand, by setting the weight average molecular weight Mw to 15000 or more, it is possible to suppress a decrease in leveling property of the paint forming the resin layer that causes interference fringes.

  In this invention, the compounding quantity of the cellulose ester to the coating material for resin layers of the outermost layer has the preferable range of 0.5 to 2 weight% with respect to all the coating materials. By making a compounding quantity into 2 weight% or less, the raise of the coating-material viscosity which forms the resin layer which causes an interference fringe can be suppressed. On the other hand, by setting the blending amount to 0.5% by weight or more, it is possible to suppress a decrease in leveling property of the paint forming the resin layer that causes interference fringes. In addition, the blending amount of 0.5 to 2% by weight of the cellulose ester with respect to the total paint is blending amount of 2 to 8 as the solid content of the cellulose ester with respect to the solid content of the total resin (the entire resin of the outermost layer containing the cellulose ester). It corresponds to% by weight. Further, an acrylic leveling agent or the like can be used in combination as long as the desired effects of the present invention are not impaired.

  The optical film of the present invention has antifouling properties by adding antiglare properties in addition to antifouling properties by containing inorganic fine particles and / or organic fine particles in any resin layer provided on the transparent film. It can be set as an anti-glare hard coat film. In particular, an excellent antiglare effect is exhibited by containing inorganic fine particles and / or organic fine particles in the outermost layer.

  In the present invention, inorganic fine particles contained for imparting antiglare properties include silica, alumina, zirconia, titanium, indium, zinc, tin, antimony, magnesium, talc, and the like, and organic fine particles include acrylic resin, polystyrene resin, Examples include, but are not limited to, silicon resins, polyethylene resins, epoxy resins, polycarbonate resins, melamine resins and the like, and composites such as acrylic-styrene resins and melamine-silica. In addition, these inorganic fine particles and organic fine particles may be used alone or in combination of two or more. Among these inorganic fine particles, silica is preferably used from the viewpoint of transparency and resolution. When organic fine particles are used, it is preferable to use one having a small difference between the refractive index in monodispersion and the refractive index of the resin.

  In the present invention, the particle diameter of the inorganic fine particles and / or organic fine particles is preferably in the range of 0.5 to 5 μm, more preferably in the range of 0.5 μm to 3 μm. When the particle size is less than 0.5 μm, it is difficult to obtain an antiglare property, and since the blending amount must be increased, adhesion and coating properties are lowered. On the other hand, when the particle diameter exceeds 3 μm, the haze (for example, due to haze specified in JIS-K7136) tends to increase, and the amount of blending decreases, resulting in poor glare.

  In addition, the above-mentioned inorganic fine particles and / or organic fine particles preferably have an oil absorption of 200 ml / 100 g or less, more preferably 150 ml / 100 g or less. By making the oil absorption 200ml / 100g or less, it is better for uneven distribution of particles below the coating film, and when it exceeds 200ml / 100g, the particles tend to be unevenly distributed above the coating film. Visibility deteriorates because the sharpness and scratch resistance deteriorate and the coating film also becomes whitish.

  Furthermore, the specific gravity of the inorganic fine particles and / or organic fine particles is selected to be higher than the specific gravity of the resin of the resin layer containing these inorganic fine particles and / or organic fine particles, and the refractive index difference is 0.03 to 0.1. It is preferable to do. In order to make the particles unevenly distributed below the resin layer by selecting particles (inorganic fine particles and / or organic fine particles) having a specific gravity and refractive index relative to the resin of the resin layer containing these particles, The glare and whitishness can be reduced, and furthermore, the antiglare property of 60 ° specular gloss (depending on the specular gloss specified in JIS-K5600) can be 100 ° or less.

  In the optical film of the present invention, in order to obtain a suitable antiglare property, the blending amount of the inorganic fine particles and / or the organic fine particles is based on the weight of the total resin of the resin layer containing the inorganic fine particles and / or the organic fine particles. It is preferably 5 to 20% by weight.

  Moreover, the thickness of the resin layer containing inorganic fine particles and / or organic fine particles needs to be thick enough to allow these particles to be unevenly distributed, and the thickness of the resin layer with respect to a suitable particle diameter of 0.5 to 5 μm is, for example, It is preferable that it is the range of 3-7 micrometers. When the thickness of the resin layer containing inorganic fine particles and / or organic fine particles is less than 3 μm, the particles cannot be unevenly distributed and may be exposed from the surface layer. Abrasion becomes worse. On the other hand, when the thickness of the resin layer exceeds 7 μm, it is difficult to obtain a suitable antiglare property, and the 60-degree specular gloss becomes larger than 100 degrees.

  Although the solvent mix | blended with a resin layer in this invention is not restrict | limited in particular, It can select suitably from an aqueous system and an organic solvent. For example, ketones such as methyl ethyl ketone, methyl isobutyl ketone and diacetone alcohol, esters such as ethyl acetate and butyl acetate, aromatic compounds such as toluene and cyclohexane, alcohols such as isopropyl alcohol and normal propyl alcohol, ethylene glycol monoethyl Examples include ethers such as ether and ethylene glycol monobutyl ether, and water. These solvents may be used alone or in combination of two or more. Moreover, as solid content concentration of the coating material for resin layers, it is preferable that it is the range of about 20 to 60% from points, such as coating property and a dry load.

  In the present invention, wet coating is particularly preferable as a method for coating the resin layer on the transparent film. For example, it can be appropriately selected from roll coating, gravure coating, slot die coating, die coating, knife coating, bar coating, spin coating, curtain coating and the like.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these Examples.
The average particle size of the fine particles was measured with a laser diffraction particle size measuring instrument “SALD2200” manufactured by Shimadzu Corporation. The coating thickness was measured by observing a cross section with a scanning electron microscope “VE-7800” manufactured by Keyence Corporation. Unless otherwise specified, “parts” and “%” described below represent “parts by weight” and “% by weight”, respectively.

<Example 1>
(Paint 1)
Silica fine particle internally added acrylic ultraviolet curable resin (trade name: Z7537, manufactured by JSR Corporation) is diluted with normal propyl alcohol so that the solid content concentration of the coating is 40%, and a photopolymerization initiator (Ciba Co., Ltd.) is obtained. 5% of Specialty Chemicals (trade name: Irgacure 184) was added to the resin and stirred for 5 minutes to prepare Paint 1. This paint 1 was applied to a 80 μm thick triacetylcellulose film (Fuji Film Co., Ltd., trade name: FujiTAC) with a bar coating thickness of 7 μm, dried by heating at 80 ° C. for 1 minute, and then a fusion-free electrode A film was formed by irradiating ultraviolet rays with an integrated light quantity of 300 mJ / cm ^{2 with} a lamp.

(Paint 2)
15 g of toluene, amorphous silica particles having an average particle size of 2.4 μm (standard deviation 0.13) and an oil absorption of 120 ml / 100 g (manufactured by Tosoh Silica Co., Ltd., trade name: Nipsil E-75, refractive index: 1. 45, an apparent specific gravity of 0.26 g / ml) is dispersed, and then an ultraviolet curable urethane-based oligomer resin (Nippon Synthesis Co., Ltd.) is prepared so that the solid content concentration of the paint is 35% and the ratio of resin to pigment is 80:20. Chemical Industry Co., Ltd., trade name: Violet UV-1700B, refractive index 1.58, specific gravity 1.15 g / ml) mixed, photopolymerization initiator (Ciba Specialty Chemicals, trade name: Irgacure) 184) is added to the resin in an amount of 5%, and cellulose acetate butyrate (made by Eastman Chemical Japan Co., Ltd., trade name: CAB553-0.4) having a weight average molecular weight Mw of 20000 is 1% to the liquid. Blended and stirred for 5 minutes to prepare paint 2. This paint 2 is coated with a bar on the triacetyl cellulose film (Fuji Film Co., Ltd., trade name: FujiTAC) coated with the paint 1 so that the film thickness is 4 μm, and heated at 80 ° C. for 1 minute. After drying, an ultraviolet light having an integrated light amount of 300 mJ / cm ² was irradiated with a fusion electrodeless lamp to produce an optical film having antiglare properties (Example 1).

<Example 2>
(Paint 3)
5 g of melamine resin particles (trade name: EPOSTAR M30, manufactured by Nippon Shokubai Co., Ltd.) having an average particle size of 3.2 μm (standard deviation 0.13, specific gravity 1.4, refractive index 1.57) were dispersed in 15 g of toluene. After that, ultraviolet curable urethane oligomer resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Shikou UV-1700B) so that the solid content concentration of the paint is 45% and the ratio of resin to pigment is 90:10 A cellulose acetate butyrate having a weight average molecular weight Mw of 70000 (Eastman Chemical Japan) was added to the resin, and a photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to the resin. Co., Ltd., trade name: CAB381-20) was mixed with 0.5% of the liquid and stirred for 5 minutes to prepare paint 3. This paint 3 was bar coated on a 80 μm thick triacetyl cellulose film (Fuji Film Co., Ltd., trade name: FujiTAC) so that the film thickness was 5 μm, and after heating and drying at 80 ° C. for 1 minute, no fusion An optical film (Example 2) having an antiglare property was produced by irradiating ultraviolet rays with an integrated light quantity of 300 mJ / cm ^{2 with} an electrode lamp.

<Example 3>
The same as Example 1 except that the weight average molecular weight of cellulose acetate butyrate blended in paint 2 of Example 1 was changed to 12000 (Eastman Chemical Japan Co., Ltd., trade name: CAB321-0.1). Thus, an optical film having antiglare properties (Example 3) was produced.

<Example 4>
(Paint 4)
The amount of oil absorption of the amorphous silica particles blended in the paint 2 of Example 1 is 240 ml / 100 g (manufactured by Tosoh Silica Co., Ltd., trade name: Nipsil N-300A), and the ratio of blending resin and pigment is An optical film having antiglare properties (Example 4) was produced in the same manner as in Example 1 except that the ratio was 86:14.

<Example 5>
(Paint 5)
The amorphous silica particles to be blended in the paint 2 of Example 1 were amorphous silica particles having a particle diameter of 3.8 μm (standard deviation 0.11) and an oil absorption of 110 ml / 100 g (manufactured by Fuji Silysia Chemical Co., Ltd., trade name) : SYLOPHOBIC505), antiglare properties were the same as in Example 1 except that the ratio of the resin and the pigment was 90:10 and that the coating film thickness was 5 μm. An optical film having Example (Example 5) was produced.

<Example 6>
An optical film having anti-glare properties (Example 6) was produced in the same manner as in Example 1 except that the thickness of the coating film of the paint 2 of Example 1 was changed to 3 μm.

<Example 7>
An optical film having anti-glare properties (Example 7) was produced in the same manner as in Example 1 except that the thickness of the coating film of the paint 2 of Example 1 was changed to 5 μm.

<Example 8>
An optical film having anti-glare properties (Example 8) was produced in the same manner as in Example 1 except that the amount of cellulose acetate butyrate added to the paint 2 of Example 1 was changed to 3% with respect to the liquid.

<Example 9>
UV curable urethane oligomer resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Shikou UV-1700B) and photopolymerization initiator (manufactured by Ciba Specialty Chemicals, trade name: Irgacure 184, blending amount: resin) 5%), cellulose acetate butyrate (manufactured by Eastman Chemical Japan Co., Ltd., trade name: CAB381-20, blending amount: 1.0% to the liquid), and the solid content concentration of the paint is 45% Then, ethyl acetate: ethyl cellosolve = 6: 4 was added and stirred for 5 minutes to prepare a coating material. This paint was applied to a 80 μm thick triacetyl cellulose film (Fuji Film Co., Ltd., trade name: FujiTAC) with a bar coating thickness of 5 μm, dried by heating at 80 ° C. for 1 minute, and then a fusion electrodeless lamp. An optical film (Example 9) was produced by irradiating ultraviolet rays with an integrated light amount of 300 mJ / cm ² .

<Example 10>
Optical having antiglare properties in the same manner as in Example 1 except that the cellulose ester blended in the paint 2 of Example 1 was changed to cellulose acetate (trade name: CA398-3, manufactured by Eastman Chemical Japan Co., Ltd.). A film (Example 10) was produced.

<Example 11>
Antiglare properties in the same manner as in Example 1 except that the cellulose ester compounded in the paint 2 of Example 1 was changed to cellulose acetate propionate (trade name: CAP482-20, manufactured by Eastman Chemical Japan Co., Ltd.). An optical film having Example (Example 11) was produced.

<Comparative Example 1>
(Paint 6)
5 g of amorphous silica particles having an average particle diameter of 2.4 μm (standard deviation 0.13) and an oil absorption of 120 ml / 100 g (manufactured by Tosoh Silica Co., Ltd., trade name: Nipsil E-75) are dispersed in 15 g of toluene. After that, an ultraviolet curable urethane oligomer resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Shikou UV) so that the solid content concentration of the paint is 30% and the ratio of the resin and the pigment is 86:14 1700B), 5% of a photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemical Co., Ltd.) is added to the resin, and a perfluoroalkyl group-containing fluorosurfactant (DIC) A paint 6 was prepared by blending 0.05% of a liquid solution manufactured by Co., Ltd., and trade name: Megafac F-479) and stirring for 5 minutes. This paint 6 was bar coated on a triacetylcellulose film (Fuji Film Co., Ltd., trade name: FujiTAC) coated with paint 1 (Example 1) so that the film thickness was 3 μm, and 80 ° C. After heating and drying for 1 minute, an ultraviolet light having an integrated light amount of 300 mJ / cm ² was irradiated with a fusion electrodeless lamp to produce an antiglare optical film (Comparative Example 1).

<Comparative example 2>
An optical film having antiglare properties in the same manner as in Example 1 except that the amount of cellulose acetate butyrate added to paint 2 of Example 1 was 0% (that is, cellulose acetate butyrate was not added) (Comparison) Example 2) was prepared.

<Comparative Example 3>
UV curable urethane oligomer resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Shikou UV-1700B) and photopolymerization initiator (manufactured by Ciba Specialty Chemicals, trade name: Irgacure 184, blending amount: resin) 5%), polyglycerin fatty acid ester (manufactured by Riken Vitamin Co., Ltd., trade name: Poem L-021, blending amount: 1.0% to the liquid) and the solid content concentration of the paint is 45%. Ethyl acetate: ethyl cellosolve = 6: 4 was added and stirred for 5 minutes to prepare a coating material. This paint was applied to a 80 μm thick triacetyl cellulose film (Fuji Film Co., Ltd., trade name: FujiTAC) with a bar coating thickness of 5 μm, dried by heating at 80 ° C. for 1 minute, and then a fusion electrodeless lamp. The optical film (Comparative Example 3) was produced by irradiating ultraviolet rays with an integrated light amount of 300 mJ / cm ² .

(Evaluation method)
The following evaluation items were evaluated for the optical films of Examples and Comparative Examples produced as described above. The results are summarized in Tables 1 and 2 below.

<Surface free energy>
In accordance with the wetting tension test method defined in JIS-6768 (1999 edition), the measurement was performed using a mixture for a wetting tension test manufactured by Wako Pure Chemical Industries, Ltd.
<Dirt (antifouling property)>
A black vinyl tape (Nitto Vinyl Tape, PROSELF No. 21 (wide)) is pasted on the film surface opposite to the antiglare layer (resin layer), and the subject's finger is slowly pushed onto the surface of the antifouling layer (resin layer). It was visually evaluated according to the following criteria whether the attached fingerprint could be visually recognized. The attached fingerprint was lightly wiped with Kimwipe (manufactured by Crecia Co., Ltd., Wiper S-200), and the ease of wiping was visually evaluated according to the following criteria.
○: Fingerprints are not conspicuous and can be easily wiped off ×: Fingerprints are conspicuous but can be easily wiped off ××: Fingerprints are conspicuous and difficult to wipe off

<Interference fringes>
A liquid crystal display (LCD) with a resolution of 50, 70, 90, 120, 150, and 200 ppi with a clear hard coat film installed is displayed in green on the entire surface, and each optical film is superimposed on the display to generate interference fringes. It was evaluated visually according to the following criteria.
◎: No interference ○: Slight interference fringes are observed but there is no problem in visibility ×: Interference fringes occur and visibility deteriorates

<Haze>
The haze was measured using a haze meter “HM150” manufactured by Murakami Color Research Laboratory in accordance with the haze measurement method defined in JIS-K7136 (2000 version).

<Whiteness>
A black vinyl tape (Nitto Vinyl Tape, PROSELF No. 21 (wide)) is bonded to the film surface opposite to the antiglare layer (resin layer), and a Macbeth densitometer “RD-918” manufactured by Sakata Inx Engineering Co., Ltd. is used. And evaluated according to the following criteria.
A: 2.05 or more ○: 2.00 or more and less than 2.05 Δ: 1.90 or more and less than 2.00 ×: less than 1.90

<Glitter>
A liquid crystal display (LCD) with a resolution of 150 ppi with a clear hard coat film is displayed in green on the entire surface, and each optical film is superimposed on this display to visually observe the degree of glittering (visibility) of the screen. Was evaluated according to the following criteria.
◎: No glare ○: Slight glare x: Large glare and poor visibility

<Abrasion resistance>
Place a steel wool bonster # 0000 on the coating and place a load of 200 g / cm ² on it, then reciprocate the load with steel wool 10 times. Judged.
◎: No scratch ○: Less than 10 scratches ×: 10 or more scratches

<Glossiness>
The measurement was performed using a gloss meter “GM-3D” manufactured by Murakami Color Research Laboratory in accordance with a measuring method of 60 ° specular glossiness defined in JIS-5600 (1999 edition).

<Coating property>
The straightness (before heating and drying) within 5 seconds immediately after the bar coating and the straightness of the coating film after film formation were visually evaluated according to the following criteria.
◎: Smooth coating immediately after coating and after film formation ○: Straight after coating, but smooth after coating △: Straight after coating, slightly after coating Poit ×: The coating film immediately after coating and after film formation is also streaky

  As can be seen from the results of Tables 1 and 2, according to the optical films of the examples of the present invention, both have excellent antifouling properties against the adhesion of fingerprints or the like due to biological lipid components such as sebum. In addition, an optical film having the interference fringes suppressed can be obtained. In particular, the weight average molecular weight Mw of the cellulose ester contained in the outermost layer is in the range of 15,000 to 75000, or the blending amount of the cellulose ester is 0.5 to 2% by weight (outermost layer) with respect to the total coating of the outermost layer. The solid content of the cellulose ester is in the range of 2 to 8% by weight relative to the solid content of all the resins), so that the effect of suppressing the occurrence of interference fringes is excellent.

On the other hand, in the case of the optical film of Comparative Example 2 in which no additive such as a leveling agent is added to the resin layer of the optical film, the anti-stain property to some extent is obtained, but the leveling property and coating property of the paint are good. Since it is bad, generation | occurrence | production of the interference fringe of the film by coating unevenness cannot be suppressed. In addition, in the case of the optical film of Comparative Example 1 in which the surface free energy of the film is reduced by adding a fluorosurfactant to the resin layer of the optical film, the effect of suppressing the generation of interference fringes can be obtained, but antifouling As for the property, when the dirt such as fingerprints is wiped off, if the dirt adheres to the film, it becomes a drop or sphere and becomes easily noticeable, and the antifouling property cannot be sufficiently obtained. Further, in the case of the optical film of Comparative Example 3 in which a fatty acid ester is added to the resin layer of the optical film, the fatty acid ester and the sebum component of dirt such as fingerprints are structurally similar. However, it is difficult to wipe off and sufficient antifouling properties cannot be obtained. Moreover, since the leveling property and coating property of a paint to which a fatty acid ester or the like is added are reduced, the generation of interference fringes due to uneven coating cannot be suppressed. In short, the optical film of the comparative example has a problem that it is impossible to achieve both antifouling properties and suppression of interference fringes.

Claims (9)

In an optical film in which one or more resin layers are provided on at least one surface of a transparent film, the outermost resin layer contains a fluorine atom-containing resin or additive that reduces surface free energy, a siloxane-based resin or a silicone-based resin or additive An optical film characterized by not containing an agent, containing a cellulose ester, and having a surface free energy of 31 mN / m or more . The optical film according to claim 1, wherein the cellulose ester is cellulose acetate butyrate. The cellulose ester, an optical film according to claim 1 or 2, wherein the weight average molecular weight Mw is in the range of 15,000 to 75,000.   The blending amount of the cellulose ester is such that the solid content of the cellulose ester is in the range of 2 to 8% by weight with respect to the solid content of the entire resin of the outermost layer. The optical film as described. The optical film according to any one of claims 1 to 4 , wherein the resin layer contains inorganic fine particles and / or organic fine particles. 6. The optical film according to claim 5 , wherein the inorganic fine particles and / or the organic fine particles have a particle diameter in the range of 0.5 to 5 [mu] m and an oil absorption of 200 ml / 100 g or less. The optical film according to claim 5 or 6 , wherein the specific gravity of the inorganic fine particles and / or organic fine particles is higher than the specific gravity of the resin of the resin layer containing the inorganic fine particles and / or organic fine particles. The refractive index difference between the inorganic fine particles and / or organic fine particles and the resin of the resin layer containing the inorganic fine particles and / or organic fine particles is in the range of 0.03 to 0.1. Item 8. The optical film according to any one of Items 5 to 7 . The optical film according to any one of claims 1 to 8 , wherein the optical film has a 60-degree specular gloss of 100 degrees or less and a haze of 15% or less.