JP2017182080A - Optical film, polarizing plate, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film which can suppress lowering of transparency of an antistatic hard coat layer and occurrence of interference fringes while improving antistatic property, and is also excellent in adhesion.SOLUTION: A method for producing an optical film includes: applying a photocurable resin composition for antistatic hard coat layer, which contains at least one of chain-like metal oxide particles formed of two or more conductive metal oxide particles connected in a chain film, a photopolymerizable monomer, urethane (meth) acrylate having 6 or more photo-polymerizable functional groups and a weight average molecular weight of 1,000 or more and polymer (meth)acrylate having 10 or more photopolymerizable functional groups and a weight average molecular weight of 10,000 or more, and a permeable solvent having permeability to a light-transmissive base material 1A, onto the surface of the light-transmissive base material 1A; drying the photocurable resin composition to form a mixed layer; curing the mixed layer by irradiation with light; and forming an antistatic hard coat layer 7 formed of a second hard coat layer 6 on a first hard coat layer 5.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical film, a polarizing plate, and an image display device.

  The image display surface of an image display device such as a liquid crystal display (LCD), a cathode ray tube display (CRT), a plasma display (PDP), an electroluminescence display (ELD), or a field emission display (FED) is usually scratch-resistant. A functional layer provided with functions such as functions is provided. As one of the functional layers, there is an antistatic hard coat layer having both an abrasion resistance function and an antistatic function (see, for example, Patent Document 1).

  When forming the antistatic hard coat layer, the antistatic hard coat layer composition containing an antistatic agent is usually applied on a light-transmitting substrate and dried. Then, the dried antistatic hard coat layer composition is irradiated with ultraviolet rays and cured to form an antistatic hard coat layer.

  When using a single conductive metal oxide particle as an antistatic agent, if the amount of conductive metal oxide particles added is small, the conductive metal oxide particles are uniformly dispersed in the antistatic hard coat layer, The distance between the conductive metal oxide particles is increased. For this reason, there is a problem that the conductive path formed by contact between the conductive metal oxide particles is difficult to form, and the antistatic property is inferior.

  Therefore, when using a single conductive metal oxide particle, the amount of the conductive metal oxide particle is increased, for example, the conductive metal oxide particle is a composition for an antistatic hard coat layer. Addition is made so that the amount of the binder component in the product is almost the same amount, and the conductive metal oxide particles are aggregated to form a conductive path to obtain antistatic properties.

  However, when the addition amount of the conductive metal oxide particles is increased, the amount of the conductive metal oxide particles is large, so that there is a problem that the haze increases and the transparency decreases. In addition, since the amount of the conductive metal oxide particles is large, some of the conductive metal oxide particles sink, and the conductive metal oxide particles are present at the interface between the antistatic hard coat layer and the light-transmitting substrate. They are lined up. For this reason, there is a problem that a difference in refractive index between the antistatic hard coat layer and the light-transmitting base material changes abruptly in the vicinity of these interfaces, and interference fringes are generated.

  Moreover, when the addition amount of electroconductive metal oxide particle is increased, the adhesiveness of a light transmissive base material and an antistatic hard-coat layer may deteriorate. Furthermore, when another layer is provided on the antistatic hard coat layer, the adhesion between the antistatic hard coat layer and another layer may deteriorate.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2006-126808) discloses that an antistatic layer is formed separately from the hard coat layer and cracks are formed in the antistatic layer. In Patent Document 2, the antistatic layer is cracked to prevent interference fringes at the interface between the antistatic layer and the light-transmitting substrate. However, since the antistatic layer is provided separately, A new interface is generated between the coating layer and the coating layer (see FIGS. 3 and 4 of Patent Document 2). Therefore, it may be possible to suppress the generation of interference fringes by cracking the antistatic layer, but this is insufficient from the viewpoint of suppressing the generation of interference fringes.

JP 2006-130667 A

  The present invention has been made to solve the above problems. That is, a method for producing an optical film that can obtain excellent antistatic properties and can suppress a decrease in transparency of the antistatic hard coat layer, can sufficiently suppress the generation of interference fringes, and has excellent adhesion, And it aims at providing such an optical film, a polarizing plate, and an image display apparatus provided with the same.

  According to one aspect of the present invention, a chain metal oxide particle composed of two or more conductive metal oxide particles linked in a chain form on the surface of a light transmissive substrate, a photopolymerizable monomer, At least one of urethane (meth) acrylate having a weight average molecular weight of 1000 or more having 6 or more photopolymerizable functional groups and polymer (meth) acrylate having a weight average molecular weight of 10,000 or more having 10 or more photopolymerizable functional groups; A photocurable resin composition for an antistatic hard coat layer containing a permeable solvent having permeability to the light transmissive substrate is applied and dried, and the light is applied to the top of the light transmissive substrate. A mixed layer in which the main component of the transparent substrate and the photopolymerizable monomer are mixed is formed, and the chain metal oxide particles, the photopolymerizable monomer, and the urethane (meth) a are formed on the mixed layer. A step of forming a chain metal oxide particle-containing layer containing at least one of relate and the polymer (meth) acrylate, and curing the mixed layer and the chain metal oxide particle-containing layer by light irradiation, A first hard coat layer which is a cured product of the mixed layer, and a second hard coat layer which is a cured product of the chain metal oxide particle-containing layer and which is formed on the first hard coat layer; A step of forming an antistatic hard coat layer comprising, the content of the chain metal oxide particles with respect to the total solid content of the photocurable resin composition for the antistatic hard coat layer is 2 to 20% by mass A method for producing an optical film is provided.

  According to another aspect of the present invention, there is provided an optical film comprising a light transmissive substrate and an antistatic hard coat layer formed on the light transmissive substrate, wherein the antistatic hard coat layer comprises: The first hard coat layer formed on the light transmissive substrate, and the second hard coat layer formed on the first hard coat layer, the first hard coat layer, A chain metal oxide comprising two or more conductive metal oxide particles including a main component of the light-transmitting substrate and a first binder resin, wherein the second hard coat layer is connected in a chain. Urethane (meth) acrylate having a weight average molecular weight of 1000 or more and photopolymerization comprising particles and a second binder resin, wherein the second binder resin has a photopolymerizable monomer, six or more photopolymerizable functional groups Weight having 10 or more functional groups The polymer comprises a polymer with at least one of polymer (meth) acrylate having an average molecular weight of 10,000 or more, and the refractive index of the first hard coat layer is from the second hard coat layer side to the light transmissive substrate side. Gradually changing toward the refractive index of the light transmissive substrate, and between the light transmissive substrate and the first hard coat layer, and the first hard coat layer and the There is provided an optical film characterized in that no interface exists between the second hard coat layer and the second hard coat layer.

  According to another aspect of the present invention, the optical film is formed on the surface of the optical film opposite to the surface on which the first hard coat layer is formed in the light-transmitting substrate. A polarizing plate comprising a polarizing element is provided.

  According to another aspect of the present invention, there is provided an image display device comprising the optical film or the polarizing plate.

  According to the method for producing an optical film of one aspect of the present invention, since the chain metal oxide particles are used as the antistatic agent, the content of the chain metal oxide particles is the light for the antistatic hard coat layer. Even when the amount is as small as 2 to 20% by mass relative to the total solid content of the curable resin composition, excellent antistatic properties can be obtained. Further, since the content of the chain metal oxide particles is a small amount of 2 to 20% by mass with respect to the total solid content of the photocurable resin composition for an antistatic hard coat layer, the transparency of the antistatic hard coat layer is small. Deterioration can be suppressed. Furthermore, since the chain metal oxide particles are bulky compared to the single conductive metal oxide particles, the first hard coat layer and the second hard coat layer are less likely to sink. Since they are not arranged in the vicinity of the interface between the hard coat layer, it is possible to suppress a rapid change in the refractive index difference in the vicinity of the interface between the first hard coat layer and the second hard coat layer. Further, according to this manufacturing method, not only the interface between the first hard coat layer and the second hard coat layer but also the interface between the light transmissive substrate and the first hard coat layer does not exist. And the antistatic hard coat layer in which the refractive index of the first hard coat layer is changed so as to gradually approach the refractive index of the light transmissive substrate from the second hard coat layer side toward the light transmissive substrate side. Can be formed. Thereby, generation | occurrence | production of an interference fringe can fully be suppressed. An antistatic hard coat layer in which no interface exists between the light-transmitting substrate and the first hard coat layer, and no interface exists between the first hard coat layer and the second hard coat layer. Therefore, the adhesion can be improved. Further, the weight of the photocurable resin composition for antistatic hard coat layer having at least 10 photopolymerizable functional groups and urethane (meth) acrylate having at least 1000 photopolymerizable functional groups and a weight average molecular weight of 1000 or more. Since at least one of polymer (meth) acrylates having an average molecular weight of 10,000 or more is contained, the hardness of the antistatic hard coat layer can be further improved.

  In addition, according to the optical film, the polarizing plate and the image display device of another aspect of the present invention, the second hard coat layer contains chain metal oxide particles as an antistatic agent. Can be obtained, and a decrease in transparency of the antistatic hard coat layer can be suppressed. In addition, since the chain metal oxide particles are bulky compared to the single conductive metal oxide particles, they are not lined up near the interface between the first hard coat layer and the second hard coat layer, It can suppress that the refractive index difference of the 1st hard coat layer and the 2nd hard coat layer changes abruptly in the vicinity of these interfaces. Furthermore, not only the interface between the first hard coat layer and the second hard coat layer, but also the interface between the light transmissive substrate and the first hard coat layer does not exist, and the first hard coat layer does not exist. The refractive index of the coat layer changes so as to gradually approach the refractive index of the light transmissive substrate from the second hard coat layer side toward the light transmissive substrate side. Thereby, generation | occurrence | production of an interference fringe can fully be suppressed. In addition, since there is no interface between the light transmissive substrate and the first hard coat layer, and there is no interface between the first hard coat layer and the second hard coat layer, the adhesion is improved. Are better. Furthermore, the second binder resin has a photopolymerizable monomer, a urethane (meth) acrylate having a weight average molecular weight of 1000 or more having 6 or more photopolymerizable functional groups, and a weight average having 10 or more photopolymerizable functional groups. Since it contains a polymer with a polymer (meth) acrylate having a molecular weight of 10,000 or more, it has excellent hardness.

It is the figure which showed typically the manufacturing process of the optical film which concerns on embodiment. It is the figure which showed typically the manufacturing process of the optical film which concerns on embodiment. It is the figure which showed typically the manufacturing process of the optical film which concerns on embodiment. It is a schematic block diagram of the polarizing plate which concerns on embodiment. 1 is a schematic configuration diagram of an image display device according to an embodiment. It is a cross-sectional photograph of the optical film which concerns on Example 1 image | photographed using the scanning transmission electron microscope function of a scanning electron microscope. It is a cross-sectional photograph of the surface vicinity of the optical film which concerns on Example 1 image | photographed using the scanning transmission electron microscope function of a scanning electron microscope. It is the cross-sectional photograph which expanded further the surface vicinity of the optical film shown by FIG.

  Hereinafter, the manufacturing method of the optical film etc. which concern on embodiment of this invention are demonstrated, referring drawings. 1-3 is the figure which showed typically the manufacturing process of the optical film which concerns on this embodiment.

≪Method for manufacturing optical film≫
First, as shown in FIG. 1A, a light transmissive substrate 1 is prepared. The light transmissive substrate 1 is not particularly limited as long as it has light transmissive properties. Specifically, examples of the light transmissive substrate 1 include cellulose acylate, cycloolefin polymer, polycarbonate, or acrylate polymer.

  Examples of cellulose acylate include cellulose triacetate and cellulose diacetate. Examples of the cycloolefin polymer include polymers such as norbornene monomers and monocyclic cycloolefin monomers.

  Examples of the polycarbonate include aromatic polycarbonates based on bisphenols (such as bisphenol A) and aliphatic polycarbonates such as diethylene glycol bisallyl carbonate.

  Examples of the acrylate polymer include poly (meth) methyl acrylate, poly (meth) ethyl acrylate, methyl (meth) acrylate-butyl (meth) acrylate, and the like.

  Among these, cellulose acylate is preferable because of excellent light transmittance, and triacetyl cellulose is preferable among cellulose acylates. A triacetyl cellulose film (TAC film) is a light-transmitting substrate capable of setting an average light transmittance to 50% or more in a visible light region of 380 to 780 nm. The average light transmittance of the TAC film is preferably 70% or more, and more preferably 85% or more.

  As triacetyl cellulose, in addition to pure triacetyl cellulose, cellulose acetate propionate and cellulose acetate butyrate may be used in combination with components other than acetic acid as a fatty acid forming an ester with cellulose. Further, these triacetylcelluloses may be added with other additives such as other cellulose lower fatty acid esters such as diacetylcellulose, or plasticizers, ultraviolet absorbers, and lubricants as necessary.

  After preparing the light-transmitting substrate 1, a photocurable resin composition for an antistatic hard coat layer is applied to the surface of the light-transmitting substrate 1 as shown in FIG. For this purpose, the “photocurable resin composition for an antistatic hard coat layer” is referred to as “a composition for an antistatic hard coat layer”). Examples of the method for applying the antistatic hard coat layer composition include known coating methods such as spin coating, dipping, spraying, slide coating, bar coating, roll coating, gravure coating, and die coating. It is done.

<Composition for antistatic hard coat layer>
The antistatic hard coat layer composition comprises a chain metal oxide particle, a photopolymerizable monomer that becomes a part of the binder resin or the binder resin after curing by light irradiation, and a weight average having 6 or more photopolymerizable functional groups It includes at least one of urethane (meth) acrylate having a molecular weight of 1000 or more and polymer (meth) acrylate having a weight average molecular weight of 10,000 or more having 10 or more photopolymerizable functional groups, and a permeable solvent. In the present invention, “(meth) acrylate” means at least one of “acrylate” and “methacrylate”.

(Chain metal oxide particles)
The chain metal oxide particles have a form in which two or more conductive metal oxide particles are linked in a chain. Here, the “metal oxide” in the present invention is a concept including a metal oxide doped with a different metal. “Chain” is a concept including both linear and branched chains.

  The chain metal oxide particles are different from the primary particles of the conductive metal oxide particles that are simply aggregated due to the attractive force between the particles, and the conductive metal oxide particles are bonded to each other. Such chain metal oxide particles may be linear, polygonal, or curved.

  The chain metal oxide particles need only have a form in which two or more conductive metal oxide particles are linked in a chain, but 2 to 50 conductive metal oxide particles are linked in a chain. What is connected is preferable, and what connected 3-30 pieces is more preferable. The reason why the number of connected conductive metal oxide particles is in the above range is that the conductive metal oxide particles that are not connected, that is, the conductive metal oxide particles alone, can effectively reduce the surface resistance value. This is because the light transmittance of the antistatic hard coat layer may decrease and haze may increase if the number of connections exceeds 50.

  The average primary particle size of the conductive metal oxide particles is preferably 1 to 100 nm, and more preferably 5 to 80 nm. The average primary particle size of the conductive metal oxide particles is in the above range because, when the average primary particle size of the conductive metal oxide particles exceeds 100 nm, it becomes difficult to connect the conductive metal oxide particles, In addition, even if it can be made, the number of contacts of the conductive metal oxide particles decreases, so that it may be difficult to effectively reduce the surface resistance value. Also, if the average primary particle size of the conductive metal oxide particles exceeds 100 nm, the light absorption by the conductive metal oxide particles increases, the light transmittance of the antistatic hard coat layer decreases, and the antistatic property This is because the haze value of the hard coat layer may be increased. In addition, when the average particle diameter of the conductive metal oxide particles is less than 1 nm, the grain boundary resistance increases rapidly, so that the surface resistance value may not be effectively reduced.

  The above-mentioned “average primary particle size” means a value measured by using a Microtrac particle size analyzer manufactured by Nikkiso Co., Ltd. in the composition, and in a cured film, a transmission electron microscope (TEM) of a cross section of the cured film. ) It means an average value of 10 conductive metal oxide particles observed by a photograph or a scanning transmission electron microscope (STEM) photograph. Specifically, for example, 10 conductive metal oxide particles in a cross-sectional photograph taken at a magnification (for example, 200,000 times) that allows confirmation of the size of one conductive metal oxide particle as shown in FIG. The average primary particle diameter of the conductive metal oxide particles in the cured film can be determined by selecting and measuring the diameters of the selected conductive metal oxide particles and determining the average value thereof.

  The average length of the chain metal oxide particles in the cured film when the cured film is observed in cross section is preferably 10 to 500 nm. The reason why the average length of the chain metal oxide particles is in the above range is that if the average length is less than 10 nm, the contact resistance may increase and the surface resistance value may not be effectively reduced. In addition, if it exceeds 500 nm, the transparency of the second hard coat layer may not be obtained. “The average length of chain metal oxide particles in the cured film” means a chain conductive metal observed by a transmission electron microscope (TEM) photograph or a scanning transmission electron microscope (STEM) photograph of a cross section of the cured film. It shall mean the average value of 10 oxide particles. Specifically, for example, a cross section taken at a magnification (for example, 200,000 times or more) at which one size of chain-like conductive metal oxide particles in which two or more conductive metal oxide particles are connected can be confirmed. By selecting 10 chain conductive metal oxide particles in the photograph, measuring the length of the longest part of the selected chain conductive metal oxide particles, and calculating the average value thereof, the chain in the cured film is obtained. The average length of the conductive metal oxide particles can be determined. The chain metal oxide particles exist in various shapes such as a curved shape, but the length can be measured by placing a thread-like object on the photograph and tracing the various shapes. .

The conductive metal oxide particles are not particularly limited as long as they are conductive metal oxide particles. For example, antimony-doped tin oxide (abbreviation: ATO), phosphorus-doped tin oxide (abbreviation: PTO), tin-doped indium oxide. (abbreviation; ITO), aluminum-doped zinc oxide (abbreviation; AZO), gallium-doped zinc oxide _{(abbreviation; GZO), ZnO, CeO 2} , Sb 2 O 5, SnO 2, In 2 O 3, and _Al 2 _{O 3} Can be mentioned.

  The content of the chain metal oxide particles with respect to the total solid content of the antistatic hard coat layer composition needs to be 2 to 20% by mass. This range is preferred because if the content of the chain metal oxide particles is less than 2%, the intended antistatic performance may not be exhibited, and if it exceeds 20%, The antistatic hard coat layer may become less transparent and the haze value may increase while the storage performance of the antistatic hard coat layer composition may deteriorate. Because there is. In the present invention, when a polymerization initiator is contained in the composition for an antistatic hard coat layer, the polymerization initiator is not converted as a solid content.

  The chain metal oxide particles can be obtained as follows. First, an alcohol solution containing metal salt or metal alkoxide at a concentration of 0.1 to 5% by mass is heated and hydrolyzed. At this time, warm water or alkali is added as necessary. By such hydrolysis, a gel dispersion of a metal hydroxide having a primary particle diameter of 1 to 100 nm is prepared. Next, the gel dispersion is filtered and washed, and fired in air at a temperature of 200 to 800 ° C. to prepare conductive metal oxide particles.

  Next, the powder is dispersed in at least one of acidic or alkaline water and an alcohol solvent to obtain a dispersion having a concentration of 10 to 50% by mass. If necessary, the dispersion is mechanically dispersed in the presence of an organic stabilizer. To do. Specific examples of organic stabilizers include gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, and citric acid. Examples thereof include carboxylic acids and salts thereof, heterocyclic compounds, and mixtures thereof. By this mechanical dispersion treatment, a sol in which the generated gel is peptized and the chain metal oxide particles are dispersed is obtained. Examples of such mechanical dispersion treatment include a sand mill method and an impact dispersion method, and the impact dispersion method is particularly preferably used.

  The chain metal oxide particles thus obtained are usually taken out of the produced dispersion by a method such as centrifugation, and washed with an acid or the like as necessary. Moreover, the obtained dispersion liquid containing a chain metal oxide can also be used as a coating liquid as it is.

  Examples of commercially available products of chain metal oxide particles include ELCOM-V3560, DP1197, DP1203, DP1204, DP1207, DP1208, etc. manufactured by JGC Catalysts and Chemicals.

(Photopolymerizable monomer)
The photopolymerizable monomer has at least one photopolymerizable functional group. The “photopolymerizable functional group” in the present invention is a functional group that can undergo a polymerization reaction by light irradiation to form a cross-linking bond between molecules. Examples of the photopolymerizable functional group include ethylenic double bonds such as a (meth) acryloyl group, a vinyl group, and an allyl group. The “(meth) acryloyl group” means at least one of “acryloyl group” and “methacryloyl group”. The “light” in the present invention includes not only electromagnetic waves having wavelengths in the visible region and wavelengths in the non-visible region such as ultraviolet rays, but also particle beams such as electron beams, and radiation or ionizing radiation that collectively refers to electromagnetic waves and particle beams. Is included. Examples of the photopolymerizable monomer include polyfunctional monomers having two or more photopolymerizable functional groups having a weight average molecular weight of less than 1000.

  Examples of the bifunctional monomer include 1,6-hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and tripropylene glycol di (meth). ) Acrylate, polyethylene glycol 400 di (meth) acrylate, hydroxypivalate ester neopentyl glycol di (meth) acrylate, bisphenol A EO modified di (meth) acrylate, isocyanuric acid di (meth) acrylate, polyester di (meth) acrylate, Bisphenol A di (meth) acrylate, adamantyl di (meth) acrylate, isobornyl di (meth) acrylate, dicyclopentane di (meth) acrylate, trisi Examples include chlorodecane di (meth) acrylate. These may be modified with ethylene oxide, propylene oxide, caprolactone, or the like.

  As the trifunctional or higher monomer, trifunctional or higher functional (meth) acryloyl monomer obtained by reacting (meth) acrylic acid or a derivative thereof with ethylene glycol, glycerin, pentaerythritol, epoxy resin or the like can be applied. For example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol octa ( (Meth) acrylate, tetrapentaerythritol deca (meth) acrylate, isocyanuric acid tri (meth) acrylate, trimethylolpropane EO modified tri (meth) acrylate, dimethylo Such as Le propane tetra (meth) acrylate.

  Among these, from the viewpoint of obtaining a hard antistatic hard coat layer, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPPA) Etc. are preferred.

  The content of the photopolymerizable monomer with respect to the total solid content of the antistatic hard coat layer composition is preferably 10 to 70% by mass. This range is preferred because if the content of the photopolymerizable monomer is less than 10% by mass, the optical laminate may not have a desired hardness, and interference fringes may also occur. If it exceeds 70% by mass, the use of a polyfunctional photopolymerizable monomer in order to improve the hardness may cause curling, and also during curing (during crosslinking reaction). This is because heat damage is caused to the optical layered body by the reaction heat of), so that wrinkles are generated and the appearance may be deteriorated.

(Urethane (meth) acrylate and polymer (meth) acrylate)
Urethane (meth) acrylate has 6 or more photopolymerizable functional groups (for example, (meth) acryloyl group) (hexafunctional) and a weight average molecular weight of 1000 or more. The weight average molecular weight of the urethane (meth) acrylate may be 1000 or more. For example, a weight average molecular weight of 1000 or more and 10,000 or less can be used. The “weight average molecular weight” is a value obtained by dissolving in a solvent such as tetrahydrofuran (THF) and converting to polystyrene by a conventionally known gel permeation chromatography (GPC) method.

  The polymer (meth) acrylate has 10 or more photopolymerizable functional groups (for example, (meth) acryloyl group) (10 functional groups) and a weight average molecular weight of 10,000 or more. The weight average molecular weight of the polymer (meth) acrylate may be 10,000 or more, but the weight average molecular weight is preferably about 10,000 to 80,000, more preferably about 10,000 to 40,000. When the weight average molecular weight exceeds 80,000, the viscosity is high, so that the coating suitability is lowered, and the appearance of the obtained optical laminate may be deteriorated.

  When the composition for an antistatic hard coat layer contains only a photopolymerizable monomer as a binder component, the antistatic hard coat layer may become brittle, but as in this embodiment, the antistatic hard coat layer When the urethane (meth) acrylate and / or polymer (meth) acrylate is included in the composition for use in addition to the photopolymerizable monomer, the antistatic hard is obtained with urethane (meth) acrylate or polymer (meth) acrylate. Toughness can be imparted to the coat layer. Thereby, the hardness of the antistatic hard coat layer can be increased. Moreover, the penetration degree of a photopolymerizable monomer can also be prepared by including the urethane (meth) acrylate and / or polymer (meth) acrylate in the antistatic hard coat layer composition. Further, when urethane (meth) acrylate is included in the composition for antistatic hard coat layer, the adhesion with another layer (for example, low refractive index layer) provided on the antistatic hard coat layer is improved. be able to.

  The functional group equivalent of the urethane (meth) acrylate and the functional group equivalent of the polymer (meth) acrylate are preferably 150 or more and 500 or less, and more preferably 160 or more and 400 or less. Here, “functional group equivalent” means a weight average molecular weight per one photopolymerizable functional group. For example, in the case of urethane (meth) acrylate having a weight average molecular weight of 1000 and having 6 or more photopolymerizable functional groups, the functional group equivalent is calculated as 1000/6 and is about 167. In the above description, the functional group equivalent of 150 or more and 500 or less is preferred because curl is unlikely to be generated if it is 150 or more, and a desired pencil hardness can be secured if it is 500 or less.

  In addition, since urethane (meth) acrylate has higher toughness than polymer (meth) acrylate, even when a functional group equivalent smaller than that of polymer (meth) acrylate is used, the antistatic hard coat layer has toughness. Can be granted. For this reason, in the urethane (meth) acrylate, the functional group equivalent can be reduced, and the weight average molecular weight can be reduced, so that the viscosity of the composition for antistatic hard coat layer is kept low and good. Coating suitability can be obtained. From such a viewpoint, urethane (meth) acrylate is more preferable than polymer (meth) acrylate.

  The content of urethane (meth) acrylate and / or polymer (meth) acrylate with respect to the total solid content of the composition for antistatic hard coat layer is preferably 10 to 70% by mass. Here, when both the urethane (meth) acrylate and the polymer (meth) acrylate are contained in the composition for antistatic hard coat layer, the above contents are urethane (meth) acrylate and polymer (meth) acrylate. And the combined content. This range is preferred because the content of urethane (meth) acrylate and / or polymer (meth) acrylate is less than 10% by mass, particularly the layer on the antistatic hard coat layer (low refractive index layer) There is a possibility that the adhesiveness of the material will deteriorate and the SW resistance described later will deteriorate. Moreover, there exists a possibility that the outstanding hardness cannot be obtained. On the other hand, if it exceeds 70% by mass, the ratio of the photopolymerizable monomer is decreased, so that interference fringes may occur.

  As the urethane (meth) acrylate, a compound obtained by reacting an isocyanate compound obtained by reacting the following polyol and diisocyanate with a (meth) acrylate monomer having a hydroxyl group can be used, but the combination is not limited.

  Examples of the polyol include polyester polyol, polyether polyol, and polycarbonate diol. The manufacturing method of polyester polyol is not specifically limited, It can manufacture with a well-known manufacturing method. For example, it can be obtained by polycondensation reaction of diol and dicarboxylic acid or dicarboxylic acid chloride, or esterification of diol or dicarboxylic acid and transesterification.

  Examples of the diol include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and dipropylene glycol. Examples of the dicarboxylic acid include adipic acid, succinic acid, glutaric acid, pimelic acid, sebacic acid, azelaic acid, maleic acid, terephthalic acid, isophthalic acid, and phthalic acid.

  Examples of the polyether polyol include polyethylene oxide, polypropylene oxide, ethylene oxide-propylene oxide random copolymerization, and the like.

  Examples of the polycarbonate diol include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, Examples include 2-ethyl-1,3-hexanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, and polyoxyethylene glycol.

  As the diisocyanate, linear or cyclic aliphatic diisocyanate or aromatic diisocyanate is used. Examples of the linear or cyclic aliphatic diisocyanate include hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylylene diisocyanate. Examples of the aromatic diisocyanate include tolylene diisocyanate and xylylene diisocyanate.

  Examples of the (meth) acrylate monomer having a hydroxyl group include ditrimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, and the like.

  Commercially available products may be used as the urethane acrylate. Examples of commercially available products include UV1700B (molecular weight 2000, 10 functional), UV6300B (molecular weight 3700, 7 functional) and UV7640B (molecular weight 1500, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.). 7 functional), DPHA40H (molecular weight 7000, 8 functional), UX5000 (molecular weight 1000, 5 functional) and UX5001T (molecular weight 6200, 8 functional) manufactured by Nippon Kayaku Co., Ltd., UN3320HS (molecular weight 5000, 15) manufactured by Negami Industrial Co., Ltd. Functional), UN904 (molecular weight 4900, 10 functional), UN3320HC (molecular weight 1500, 6 functional) and UN3320HA (molecular weight 1500, 6 functional), BS577 (molecular weight 1000, 6 functional) manufactured by Arakawa Chemical Industries, Ltd., and Shin-Nakamura Chemical Industrial Stock Board Made in U15H (15 functional) and U6H (6 functional), and the like.

  Examples of the polymer (meth) acrylate include urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

  As a commercial item of epoxy acrylate, Arakawa Chemical Industries, Ltd. beam set 371 etc. are mentioned.

(Penetration solvent)
The “permeable solvent” is a solvent that has high permeability to the light transmissive substrate and dissolves or swells the light transmissive substrate. By using the penetrating solvent, not only the penetrating solvent but also the photopolymerizable monomer can penetrate into the light-transmitting substrate.

  Examples of the permeable solvent include ketones such as acetone, methyl ethyl ketone (MEK), cyclohexanone, methyl isobutyl ketone, diacetone alcohol, cycloheptanone, and diethyl ketone; methyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate Esters such as ethyl lactate; nitrogen-containing compounds such as nitromethane, acetonitrile, N-methylpyrrolidone and N, N-dimethylformamide; glycols such as methyl glycol and methyl glycol acetate; tetrahydrofuran, 1,4-dioxane, dioxolane, Ethers such as diisopropyl ether; halogenated hydrocarbons such as methylene chloride, chloroform, tetrachloroethane; methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate, etc. Recall ethers and the like; dimethyl sulfoxide, propylene carbonate. Moreover, these mixtures may be sufficient. Among these, at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, butyl acetate, and methyl ethyl ketone is preferable.

  The amount of penetrating solvent added is preferably 50 to 500 parts by mass with respect to 100 parts by mass of the total solid content of the antistatic hard coat layer composition. This range is preferred because if the amount of the penetrating solvent added is less than 50 parts by mass, the penetrating solvent does not sufficiently penetrate the light-transmitting substrate, and interference fringes may occur. In addition, if it exceeds 500 parts by mass, the permeable solvent may dissolve or swell the light-transmitting substrate more than necessary, and the desired hardness as an optical film may not be obtained. .

(Other ingredients)
In addition to the composition for an antistatic hard coat layer, a polymerization initiator, a dispersant, a lubricant, fine particles, an antiglare agent, and the like may be added as necessary.

(Polymerization initiator)
The polymerization initiator is a component that is decomposed by light irradiation to generate radicals and initiate or advance polymerization of the photopolymerizable monomer.

  The polymerization initiator is not particularly limited as long as it can release a substance that initiates radical polymerization by light irradiation. Examples of the polymerization initiator include acetophenones, benzophenones, ketals, anthraquinones, disulfide compounds, thiuram compounds, and fluoroamine compounds. More specifically, 1-hydroxy-cyclohexyl-phenylketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, benzyldimethylketone, 1- (4-dosyl) Tesylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methyl Examples include propan-1-one and benzophenone. Among these, 1-hydroxy-cyclohexyl-phenylketone and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one initiate polymerization reaction by light irradiation even in a small amount. Since it can promote, it is preferable. Any one of the above-described polymerization initiators may be used alone or in combination of two or more.

  Examples of commercially available polymerization initiators include Irgacure (registered trademark) 184 (1-hydroxy-cyclohexyl-phenyl-ketone) and Irgacure (registered trademark) 907 (2-methyl-1- (4-methylthio) manufactured by BASF. Phenyl) -2-morpholinopropan-1-one), Irgacure® 127 (2-hydroxy-1 [4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl] -2 -Methyl-propan-1-one), Lucillin (registered trademark) TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide) and the like.

(Lubricant)
An easy lubricant (anti-blocking agent) is a component that prevents sticking when an antistatic hard coat layer and a light-transmitting substrate are superposed, such as in a roll state. As the lubricant, a conventionally known lubricant can be used. For example, fine particles of inorganic compounds such as silica and high-density polyethylene described in JP-A No. 2004-284126 having an average primary particle size of 100 to 1000 nm, Fine particles of organic compounds such as polystyrene and polystyrene acrylic can be used. The content of the lubricant is preferably 0.1 to 5% by mass with respect to the total mass of the total solid content of the antistatic hard coat layer composition.

(Hardness imparting fine particles)
The hardness-imparting fine particles are components that improve the hardness of the antistatic hard coat layer. As the fine particles, known particles that can be used for the antistatic hard coat layer may be appropriately employed depending on the required performance.

  The average particle diameter of the hardness-imparting fine particles is preferably 1 to 100 nm from the viewpoint of the transparency of the hard coat layer. By being in this range, it is easy to impart hardness while maintaining the transparency of the hard coat layer. The fine particles may be agglomerated particles, and in the case of agglomerated particles, the secondary particle size may be in the above range.

  The addition amount of the hardness-imparting fine particles in the antistatic hard coat layer composition is not particularly limited, and may be appropriately set in consideration of hardness and the like. The addition amount of the fine particles is preferably 0 to 40% by mass with respect to the total solid content of the composition for antistatic hard coat layer from the viewpoint of improving the hardness of the antistatic hard coat layer, and is 10 to 30% by mass. It is more preferable. If it exceeds 40% by mass, the antistatic performance may not be exhibited.

The fine particles may be inorganic fine particles or organic fine particles, but are preferably inorganic fine particles from the viewpoint of imparting hardness. Examples of the inorganic fine particles include silica (SiO ₂ ) fine particles and alumina fine particles.

  The silica fine particles may be subjected to surface treatment. The silica fine particles are preferably those having an ultraviolet reactive group on the surface in terms of hardness. The shape of the silica fine particles may be spherical, irregular, irregular, or chain. Examples of commercially available silica fine particles include IPA-ST, IPASTMS, and IPAST (L) manufactured by Nissan Chemical Industries, Ltd.

  Since alumina is a material having a high Mohs hardness, when alumina fine particles are used as the inorganic fine particles, the hardness can be further improved. The alumina fine particles may be subjected to a surface treatment in the same manner as the silica fine particles.

  Examples of the organic fine particles include plastic beads. Specific examples of the plastic beads include polystyrene beads, melamine resin beads, acrylic beads, acrylic-styrene beads, silicone beads, benzoguanamine beads, benzoguanamine / formaldehyde condensation beads, polycarbonate beads, polyethylene beads, and the like. The plastic beads preferably have a hydrophobic group on the surface, and examples thereof include styrene beads.

(Anti-glare agent)
The antiglare agent is a component for imparting an antiglare function to the hard coat layer. Examples of the antiglare agent include fine particles, and the shape of the fine particles may be a true sphere or an ellipse, and preferably a true sphere. The fine particles may be inorganic or organic, but those formed of an organic material are preferred. The fine particles exhibit anti-glare properties and are preferably transparent. Specific examples of the fine particles include plastic beads, and more preferably those having transparency. Specific examples of plastic beads include styrene beads (refractive index 1.59), melamine beads (refractive index 1.67), acrylic beads (refractive index 1.49), acrylic-styrene beads (refractive index 1.54), Examples thereof include polycarbonate beads and polyethylene beads.

  When the antistatic hard coat layer composition 2 is applied to the surface of the light transmissive substrate 1, a part of the permeable solvent and a part of the photopolymerizable monomer penetrate into the upper part of the light transmissive substrate 1. On the other hand, the chain metal oxide particles in composition 2 for hard coat layer, urethane (meth) acrylate having 6 or more photopolymerizable functional groups and a weight average molecular weight of 1000 or more and / or photopolymerizable functional groups. The polymer (meth) acrylate having a weight average molecular weight of 10,000 or more having 10 or more has a large size, and therefore does not penetrate into the light transmissive substrate 1 and remains on the light transmissive substrate 1.

  Next, for example, when the permeable solvent is removed by drying at 30 to 100 ° C. for 15 seconds or longer, the main component of the light transmissive substrate 2 is formed on the light transmissive substrate 1 as shown in FIG. The mixed layer 3 in which the photopolymerizable monomer is mixed is formed, and the chain metal oxide particles and the transparent substrate 1 do not penetrate into the mixed layer 3 and remain on the transparent substrate 1. A chain metal oxide particle-containing layer 4 containing a photopolymerizable monomer and the urethane (meth) acrylate and / or the polymer (meth) acrylate is formed. The light transmissive substrate 1 </ b> A after the formation of the mixed layer 3 is thinner than the light transmissive substrate 1 by the thickness of the mixed layer 3. The “main component of the light transmissive substrate” in the present invention indicates a component having the highest content ratio among the constituent components of the light transmissive substrate.

  Thereafter, as shown in FIG. 2B, the mixed layer 3 and the chain metal oxide particle-containing layer 4 are irradiated with light such as ultraviolet rays to polymerize the photopolymerizable monomer contained in the mixed layer 3. As a result, the mixed layer 3 is cured, and the photopolymerizable monomer and urethane (meth) acrylate and / or polymer (meth) acrylate contained in the chain metal oxide particle-containing layer 4 are polymerized to thereby cause chain metal oxidation. The product particle-containing layer 4 is cured. Thus, the antistatic hard coat composed of the first hard coat layer 5 which is a cured product of the mixed layer 3 and the second hard coat layer 6 which is a cured product of the chain metal oxide particle-containing layer 4. Layer 7 is formed. When ultraviolet rays are used as the light, ultraviolet rays emitted from an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, a metal halide lamp, or the like can be used.

  The first hard coat layer 5 includes a main component of the light transmissive substrate 1A and a first binder resin containing a polymer of a photopolymerizable monomer. The second hard coat layer 6 contains chain metal oxide particles and a second binder resin. The second binder resin contains a polymer of a photopolymerizable monomer and the urethane (meth) acrylate and / or the polymer (meth) acrylate. The antistatic hard coat layer 7 has a hardness of “H” or more in a pencil hardness test specified by JIS K5600-5-4 (1999).

  After forming the antistatic hard coat layer 7, as shown in FIG. 3, a low refraction having a refractive index lower than the refractive index of the antistatic hard coat layer 7 on the second hard coat layer 6 as necessary. The rate layer 8 is formed. Specifically, for example, the low refractive index layer 8 is formed on the second hard coat layer 6 with a curable resin composition for low refractive index layer (hereinafter referred to as “curable resin for low refractive index layer”). The “composition” is referred to as “a composition for a low refractive index layer”), and is dried and cured. Thereby, the optical film 10 shown by FIG. 3 is produced.

(Composition for low refractive index layer)
As the composition for a low refractive index layer, for example, a composition comprising a low refractive index component such as silica or magnesium fluoride and a photopolymerizable monomer, photopolymerizable oligomer, or photopolymerizable polymer that becomes a binder resin after curing. Things. In addition, you may add a polymerization initiator etc. in the composition for low refractive index layers. As the photopolymerizable monomer, photopolymerizable oligomer, or photopolymerizable polymer, those similar to the photopolymerizable monomer and the like mentioned in the composition for antistatic hard coat layer can be used. In addition, at least one of a monomer, an oligomer, and a polymer of an organic fluorine compound may be used. Since the organic fluorine compound has low hardness, an ultraviolet curable type is preferable.

  In addition, the composition for forming the low refractive index layer may contain hollow particles such as hollow silica particles in order to reduce the refractive index of the low refractive index layer. A hollow particle refers to a particle having an outer shell layer and the inside surrounded by the outer shell layer being a porous structure or a cavity. This porous structure or cavity contains air (refractive index: 1), and the refractive index of the low refractive index layer is obtained by including hollow particles having a refractive index of 1.20 to 1.45 in the low refractive index layer. Can be reduced. The average particle diameter of the hollow particles is preferably 1 to 100 nm. As the hollow particles, those conventionally used for a low refractive index layer can be used, and examples thereof include fine particles having voids described in JP-A-2008-165040. What is necessary is just to select the film thickness of a low refractive index layer suitably according to the performance requested | required, and it is preferable that it is 80-120 nm.

≪Optical film≫
The optical film according to the present embodiment is obtained by the above production method. That is, as shown in FIG. 3, the optical film 10 includes a light transmissive substrate 1A and an antistatic hard coat layer 7 formed on the light transmissive substrate 1A.

  The antistatic hard coat layer 7 is formed on the light transmissive substrate 1A, and includes a first hard coat layer 5 containing a main component of the light transmissive substrate 1A and a first binder resin, and a first hard A chain metal oxide particle formed on the coat layer 5 and composed of a second binder resin and two or more conductive metal oxide particles linked in a chain and dispersed in the second binder resin; And a second hard coat layer 6 containing The optical film 10 shown in FIG. 3 further includes the low refractive index layer 8, but the optical film 10 may not include the low refractive index layer 8.

  The thickness of the first hard coat layer 5 is preferably 0.5 to 10 μm. This range is preferred because if the thickness of the first hard coat layer 5 is less than 0.5 μm, the adhesion to the light-transmitting substrate may be inferior. Since light does not reach the hard coat layer sufficiently, there is a risk of causing poor curing, a permeable solvent remaining in the light-transmitting substrate after drying, or wrinkles or curls after curing. Because there is.

  The thickness of the second hard coat layer 6 is preferably 1 to 10 μm. This range is preferable because if the thickness of the second hard coat layer 6 is less than 1 μm, the hardness as the hard coat layer may be lowered. Moreover, since the light-transmitting substrate swells due to the use of the penetrating solvent, fine irregularities are formed on the surface of the light-transmitting substrate. When the thickness of the second hard coat layer is less than 1 μm, The haze increases slightly due to the unevenness, and there is a possibility that the second hard coat layer may appear white particularly when the second hard coat layer is viewed obliquely. On the other hand, when the thickness exceeds 10 μm, the light transmittance of the second hard coat layer is lowered, and there is a risk of curling and cracking. Moreover, since chain metal oxide particles are expensive, there is a risk of increasing costs.

  The refractive index of the first hard coat layer 5 gradually changes from the second hard coat layer 6 side toward the light transmissive substrate 1A side so as to approach the refractive index of the light transmissive substrate 1A. . This is because the photopolymerizable monomer penetrates the light transmissive substrate 1 from the surface side of the light transmissive substrate 1 as described above, so that the photopolymerizable monomer in the mixed layer 3 is a chain of the mixed layer 3. This is considered to be caused by a concentration gradient that gradually decreases from the metal oxide particle layer 4 side toward the light transmissive substrate 1A side.

  Such a change in refractive index can be confirmed by observation using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM) of a cross section in the film thickness direction of the optical film.

  There are no interfaces between the light transmissive substrate 1A and the first hard coat layer 5 and between the first hard coat layer 5 and the second hard coat layer 6. These interfaces mean interfaces that can be visually recognized in observation using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM) of the cross section of the optical film 10 in the film thickness direction. Therefore, if these interfaces cannot be visually recognized by observation using TEM or STEM, it is determined that there is no interface. In TEM and STEM, secondary electrons generated by electron beam irradiation are measured, so that the material constituting the upper layer and the material constituting the lower layer are mixed in a gradation at the interface between the upper layer and the lower layer. If the electron emission characteristics of secondary electrons of the substance constituting the upper layer and the substance constituting the lower layer are the same, even if an interface exists, the interface is not visually recognized by TEM observation. The absence of these interfaces can also be confirmed by the absence of interference fringes. This is because there is no layer interface without interference fringes. Interference fringes can be confirmed by attaching a black tape on the surface of the optically transparent substrate opposite to the surface on which the first hard coat layer is formed, and observing it under a three-wavelength fluorescent lamp. It is done.

From the viewpoint of obtaining excellent antistatic properties, the surface resistance value of the optical film 10 is preferably 10 ¹² Ω / □ or less, more preferably 10 ¹¹ Ω / □ or less, and more preferably 10 ¹⁰ Ω / □ or less. More preferably. If without the low refractive index layer 8 after saponified optical film, or even after wiping off the surface with a solvent, the surface resistance value is preferably 10 ¹² Ω / □ or less, 10 ¹¹ Omega / □ or less is more preferable, and 10 ¹⁰ Ω / □ or less is more preferable. The saponification treatment is performed by immersing the optical film in a NaOH or KOH aqueous solution at 40 ° C. to 70 ° C. adjusted to 1.5 to 4.5 N for 15 seconds to 5 minutes. Examples of equipment that can be used to measure the surface resistance include Hiresta HT-210 manufactured by Mitsubishi Oil Chemical Co., Ltd.

  From the viewpoint of obtaining excellent transparency, the total light transmittance of the optical film 10 is preferably 88% or more when the low refractive index layer 8 is not provided. When the low refractive index layer 8 is provided, it is preferably 90% or more, more preferably 92% or more. Further, the haze value of the optical film 10 is preferably 1.0% or less, and more preferably 0.7% or less, from the viewpoint of obtaining excellent transparency. The total light transmittance is measured according to JIS K7361, and the haze value is measured according to JIS K7136. Examples of equipment that can be used for measuring the total light transmittance and haze value include HM-150 manufactured by Murakami Color Research Laboratory. “Transparency” can be evaluated by the total light transmittance and the haze value.

  The reflection Y value of the optical film 10 is preferably 2.0% or less, more preferably 1.5% or less, and 1.2% or less from the viewpoint of preventing reflection of external light. Is more preferable, 1.0% or less is further preferable, and 0.7% or less is more preferable. Reflection Y value is a luminous reflectance calculated by software (built in MCP3100 described later) that measures 5 ° regular reflectance in a wavelength range of 380 to 780 nm, and then converts it as brightness that is perceived by human eyes. This is the value indicated by. In addition, when measuring 5 degree regular reflectance, in order to prevent the back surface reflection of the film which is an optical film, it measures by sticking a black tape on the opposite side to a measurement film surface. Examples of equipment that can be used to measure the reflection Y value include MCP3100 manufactured by Shimadzu Corporation.

The abrasion resistance of the optical film 10 is not damaged when the surface of the optical film 10 is rubbed 10 times at a speed of 100 mm / sec using # 0000 steel wool and applying a load of 100 g / cm ^2. Preferably, it is more preferable that there is no flaw when rubbing 10 times at a speed of 100 mm / sec while applying a load of 300 g / cm ² .

≪Polarizing plate≫
The optical film 10 can be used by being incorporated into a polarizing plate, for example. FIG. 4 is a schematic configuration diagram of a polarizing plate incorporating the optical film according to the present embodiment. As shown in FIG. 4, the polarizing plate 20 includes an optical film 10 and a polarizing element 21. The polarizing element 21 is formed on the surface opposite to the surface on which the first hard coat layer 5 is formed in the light transmissive substrate 1A.

  Examples of the polarizing element 21 include a polyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetal film, an ethylene-vinyl acetate copolymer saponified film, which are dyed and stretched with iodine or the like. When laminating the optical film 10 and the polarizing element 21, it is preferable to saponify the light transmissive substrate 1A in advance. By performing the saponification treatment, the adhesiveness is improved and an antistatic effect can be obtained.

≪Image display device≫
The optical film 10 and the polarizing plate 20 can be used by being incorporated in an image display device.
Examples of the image display device include a liquid crystal display (LCD), a cathode ray tube display device (CRT), a plasma display (PDP), an electroluminescence display (ELD), a field emission display (FED), a touch panel, a tablet PC, and electronic paper. Can be mentioned. FIG. 5 is a schematic configuration diagram of an image display device incorporating the optical film according to the present embodiment.

  The image display device 30 shown in FIG. 5 is a liquid crystal display. The image display device 30 includes a protective film 31, such as a triacetyl cellulose film (TAC film), a polarizing element 32, a retardation film 33, an adhesive layer 34, a liquid crystal, from the light source side (backlight side) to the viewer side. The cell 35, the adhesive layer 36, the retardation film 37, the polarizing element 21, and the optical film 10 are stacked in this order. In the liquid crystal cell 35, a liquid crystal layer, an alignment film, an electrode layer, a color filter, and the like are disposed between two glass substrates.

  Examples of the retardation films 33 and 37 include a triacetyl cellulose film and a cycloolefin polymer film. Examples of the adhesive constituting the adhesive layers 34 and 36 include a pressure sensitive adhesive (PSA).

  Since the chain metal oxide particles are bulky, the chain metal oxide particles hardly enter the light transmissive substrate 1 when the permeable solvent penetrates the light transmissive substrate 1. That is, in the optical film 10 of the present embodiment, the chain metal oxide particles are present in the second hard coat layer 6 and are not substantially present in the first hard coat layer 5. Further, since the conductive metal oxide particles are connected in a chain shape in the chain metal oxide particles, it is easier to form a conductive path than the single conductive metal oxide particles. Therefore, when the same amount of the chain metal oxide particles and the single conductive metal oxide particles are used, the chain metal oxide particles are more charged than the single conductive metal oxide particles. Preventive properties can be improved. Therefore, even if the content of the chain metal oxide particles is as small as 2 to 20% by mass based on the total solid content of the composition for antistatic hard coat layer, excellent antistatic properties can be obtained. it can.

  In this embodiment, since the content of the chain metal oxide particles is as small as 2 to 20% by mass with respect to the total solid content of the composition for antistatic hard coat layer, the increase in haze is suppressed. can do. Thereby, the fall of the transparency of the antistatic hard coat layer 7 can be suppressed.

  In this embodiment, since the chain metal oxide particles are bulky, they are difficult to sink in the second hard coat layer 6, and even if the chain metal oxide particles sink in the second hard coat layer 6. Even if it is present near the interface between the first hard coat layer 5 and the second hard coat layer 6, the chain metal oxide particles are in a chain form. The physical particles are not arranged near the interface between the first hard coat layer 5 and the second hard coat layer 6. Thereby, it can suppress that the refractive index difference of the 1st hard-coat layer 5 and the 2nd hard-coat layer 6 changes rapidly in these interface vicinity. Further, the refractive index of the first hard coat layer 5 gradually changes from the second hard coat layer 6 side toward the light transmissive substrate 1A side so as to approach the refractive index of the light transmissive substrate 1A. In addition, there are no interfaces between the light-transmitting substrate 1A and the first hard coat layer 5 and between the first hard coat layer 5 and the second hard coat layer 6. Thereby, generation | occurrence | production of an interference fringe can fully be suppressed.

  In the present embodiment, since chain metal oxide particles are used as the antistatic agent, it is possible to suppress dropout due to chemicals and the like and to improve pencil hardness.

  In the present embodiment, the antistatic hard coat layer composition 2 has 6 or more photopolymerizable functional groups and a urethane (meth) acrylate having a weight average molecular weight of 1000 or more and 10 or more photopolymerizable functional groups. Since at least one of polymer (meth) acrylates having a weight average molecular weight of 10,000 or more is contained, the hardness of the antistatic hard coat layer 7 can be further improved.

  When the antistatic hard coat layer composition 2 contains a urethane (meth) acrylate having 6 or more photopolymerizable functional groups and a weight average molecular weight of 1000 or more, the antistatic hard coat for the low refractive index layer 8 The adhesion of the layer 7 can be further improved.

  According to the present embodiment, the first hard coat layer 5 which is a part of the antistatic hard coat layer 7 is formed by allowing the photopolymerizable monomer to penetrate into the light transmissive substrate 1 with the permeable solvent. Therefore, the adhesion between the antistatic hard coat layer 7 and the light transmissive substrate 1A is also excellent.

  According to this embodiment, since the chain metal oxide particles are unevenly distributed in the surface layer portion of the antistatic hard coat layer 7, the chain metal oxide particles are uniformly dispersed in the antistatic hard coat layer. It is more difficult to curl the optical film 10. Further, since the chain metal oxide particles are unevenly distributed in the surface layer portion of the antistatic hard coat layer 7, the reflectance is higher than the case where the chain metal oxide particles are uniformly dispersed in the antistatic hard coat layer. Is low.

  In order to describe the present invention in detail, examples will be described below, but the present invention is not limited to these descriptions.

<Preparation of composition for antistatic hard coat layer>
Each component was mix | blended so that it might become the composition shown below, and the composition for antistatic hard-coat layers was obtained.
(Antistatic hard coat layer composition 1)
-Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 50 parts by mass (solid content 10 parts by mass, alcohol 40 parts by mass)
Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, Nippon Kayaku Co., Ltd., weight average molecular weight 578, hexafunctional): 45 parts by mass Urethane acrylate (Art Resin UN3320HA, Negami Industrial Co., Ltd., weight average molecular weight 1500) , Hexafunctional, functional group equivalent 250): 45 parts by massMethyl ethyl ketone (penetrating solvent): 140 parts by massPolymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

(Antistatic hard coat layer composition 2)
-Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 50 parts by mass (solid content 10 parts by mass, alcohol 40 parts by mass)
Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, Nippon Kayaku Co., Ltd., weight average molecular weight 578, 6 functional): 45 parts by mass Urethane acrylate (UV1700B, Nippon Gosei Co., Ltd., weight average molecular weight 2000, 10 Functionality, functional group equivalent 200): 45 parts by mass-Methyl ethyl ketone (penetrating solvent): 140 parts by mass-Polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

(Antistatic hard coat layer composition 3)
-Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 50 parts by mass (solid content 10 parts by mass, alcohol 40 parts by mass)
Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, Nippon Kayaku Co., Ltd., weight average molecular weight 578, 6 functional): 45 parts by mass Urethane acrylate (Art Resin UN3320HS, Negami Industrial Co., Ltd., weight average molecular weight 5000) 15 functional, functional group equivalent 333): 45 parts by mass Methyl ethyl ketone (penetrating solvent): 140 parts by mass Polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

(Antistatic hard coat layer composition 4)
-Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 50 parts by mass (solid content 10 parts by mass, alcohol 40 parts by mass)
Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, manufactured by Nippon Kayaku Co., Ltd., weight average molecular weight 578, hexafunctional): 45 parts by mass butyl acetate solution of polymer acrylate (Beamset 371, Arakawa Chemical Co., Ltd.) Manufactured, weight average molecular weight 40000, 100 functional, functional group equivalent 400): 69 parts by mass (solid content 45 parts by mass, butyl acetate 24 parts by mass)
-Methyl ethyl ketone (penetrating solvent): 140 parts by mass-Polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

(Antistatic hard coat layer composition 5)
-Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 50 parts by mass (solid content 10 parts by mass, alcohol 40 parts by mass)
・ Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, manufactured by Nippon Kayaku Co., Ltd., weight average molecular weight 578, hexafunctional): 30 parts by mass ・ Butyl acetate solution of polymer acrylate (Beamset 371, Arakawa Chemical Co., Ltd.) Manufactured, weight average molecular weight 40000, 100 functional, functional group equivalent 400): 46 parts by mass (solid content 30 parts by mass, butyl acetate 16 parts by mass)
・ Urethane acrylate (UV1700B, Nihon Gosei Co., Ltd., weight average molecular weight 2000, 10 functional, functional group equivalent 200): 45 parts by mass ・ Methyl ethyl ketone (penetrating solvent): 140 parts by mass ・ Polymerization initiator (Irgacure 184, manufactured by BASF ): 4 parts by mass

(Antistatic hard coat layer composition 6)
Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 50 parts by mass (solid content 10 parts by mass, alcohol 40 parts by mass)
Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, manufactured by Nippon Kayaku Co., Ltd., weight average molecular weight 578, 6 functional): 45 parts by mass Urethane acrylate (Art Resin UN333, Negami Industrial Co., Ltd., weight average molecular weight 5000) Bifunctional, functional group equivalent 2500): 45 parts by mass Methyl ethyl ketone (penetrating solvent): 140 parts by mass Polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

(Antistatic hard coat layer composition 7)
-Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 50 parts by mass (solid content 10 parts by mass, alcohol 40 parts by mass)
Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, Nippon Kayaku Co., Ltd., weight average molecular weight 578, 6 functional): 45 parts by mass Polymer acrylate (Art Resin UN7700, Negami Industrial Co., Ltd., weight average molecular weight 20000) Bifunctional, functional group equivalent 10,000): 45 parts by mass-Methyl ethyl ketone (penetrating solvent): 140 parts by mass-Polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

(Antistatic hard coat layer composition 8)
-Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 200 parts by mass (solid content 40 parts by mass, alcohol 160 parts by mass)
Pentaerythritol triacrylate (photopolymerizable monomer, PET30, Nippon Kayaku Co., Ltd., weight average molecular weight 298, trifunctional): 30 parts by mass Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, Nippon Kayaku Co., Ltd.) Made by company, weight average molecular weight 578, 6 functional): 30 parts by mass. Isopropyl alcohol (non-permeable solvent): 25 parts by mass. Polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass.

(Antistatic hard coat layer composition 9)
-Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 50 parts by mass (solid content 10 parts by mass, alcohol 45 parts by mass)
Pentaerythritol triacrylate (photopolymerizable monomer, PET30, Nippon Kayaku Co., Ltd., weight average molecular weight 298, trifunctional): 45 parts by mass Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, Nippon Kayaku Co., Ltd.) Made by company, weight average molecular weight 578, hexafunctional): 30 parts by mass-Isopropyl alcohol (non-permeable solvent): 140 parts by mass Polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

(Composition 10 for antistatic hard coat layer)
-Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 200 parts by mass (solid content 40 parts by mass, alcohol 160 parts by mass)
Pentaerythritol triacrylate (photopolymerizable monomer, PET30, Nippon Kayaku Co., Ltd., weight average molecular weight 298, trifunctional): 30 parts by mass Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, Nippon Kayaku Co., Ltd.) Made by company, weight average molecular weight 578, hexafunctional): 30 parts by mass / methyl ethyl ketone (penetrating solvent): 200 parts by mass / polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

(Composition 11 for antistatic hard coat layer)
-Alcohol dispersion of chain antimony-doped tin oxide (dispersion of chain metal oxide particles, ELCOM-V3560, manufactured by JGC Catalysts Co., Ltd.): 5 parts by mass (solid content 1 part by mass, alcohol 9 parts by mass)
Pentaerythritol triacrylate (photopolymerizable monomer, PET30, Nippon Kayaku Co., Ltd., weight average molecular weight 298, trifunctional): 49 parts by mass Dipentaerythritol hexaacrylate (photopolymerizable monomer, DPHA, Nippon Kayaku Co., Ltd.) 49 parts by mass, methyl ethyl ketone (permeable solvent): 172 parts by mass, polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

(Composition 12 for antistatic hard coat layer)
-Non-chain antimony-doped tin oxide methyl isobutyl ketone dispersion (dispersion of non-chain metal oxide particles, EPT5DL2MIBK, manufactured by Mitsubishi Materials Electronics Chemical Co., Ltd.): 50 parts by mass (solid content 10 parts by mass, methyl isobutyl ketone) 40 parts by mass)
Pentaerythritol triacrylate (photopolymerizable monomer, PET30, manufactured by Nippon Kayaku Co., Ltd., weight average molecular weight 298, trifunctional): 30 parts by mass Urethane acrylate (UV1700B, Nippon Gosei Co., Ltd., weight average molecular weight 2000, 10 functional) , Functional group equivalent 200): 30 parts by mass-Isopropyl alcohol (non-permeable solvent): 25 parts by mass-Polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

(Antistatic hard coat layer composition 13)
-Non-chain antimony-doped tin oxide methyl isobutyl ketone dispersion (dispersion of non-chain metal oxide particles, EPT5DL2MIBK, manufactured by Mitsubishi Materials Electronics Chemical Co., Ltd.): 200 parts by mass (solid content 40 parts by mass, methyl isobutyl ketone) 160 parts by mass)
Pentaerythritol triacrylate (photopolymerizable monomer, PET30, manufactured by Nippon Kayaku Co., Ltd., weight average molecular weight 298, trifunctional): 30 parts by mass Urethane acrylate (UV1700B, Nippon Gosei Co., Ltd., weight average molecular weight 2000, 10 functional) , Functional group equivalent 200): 30 parts by mass-Isopropyl alcohol (non-permeable solvent): 25 parts by mass-Polymerization initiator (Irgacure 184, manufactured by BASF): 4 parts by mass

<Preparation of composition for low refractive index layer>
Each component was mix | blended so that it might become the composition shown below, and the composition for hard-coat layers was obtained.
(Composition for low refractive index layer)
・ Methyl isobutyl ketone dispersion of hollow treated silica fine particles (manufactured by JGC Catalysts Co., Ltd., average particle size 60 nm): 60 parts by mass (solid content 20% by mass)
Pentaerythritol triacrylate (PET30, Nippon Kayaku Co., Ltd., trifunctional): 10 parts by massReactive silicone (X22164E, Shin-Etsu Chemical Co., Ltd.): 0.6 parts by massMethyl isobutyl ketone: 350 parts by mass Propylene glycol monomethyl ether acetate: 161 parts by mass-polymerization initiator (Irgacure 127, manufactured by BASF): 0.4 parts by mass

<Example 1>
On one surface of a 40 μm thick triacetylcellulose base material (KC4UY, manufactured by Konica Minolta Co., Ltd.), the antistatic hard coat layer composition 1 was applied using a roll coating method to form a coating film. The coating film was dried at 70 ° C. for 60 seconds, and then irradiated with ultraviolet rays at an irradiation amount of 100 mJ / cm ² using an ultraviolet irradiation device to cure the coating film. Thus, a first hard coat layer having a dry film thickness of 4 μm containing triacetyl cellulose and a polymer of dipentaerythritol hexaacrylate, a polymer of dipentaerythritol hexaacrylate and urethane acrylate, and chain antimony-doped tin oxide An antistatic hard coat layer comprising a second hard coat layer having a dry film thickness of 1.5 μm containing Furthermore, the low refractive index layer composition was applied to the surface of the second hard coat layer to form a coating film. The coating film was dried at 70 ° C. for 60 seconds, and then irradiated with ultraviolet rays at an irradiation amount of 150 mJ / cm ² using an ultraviolet irradiation device to cure the coating film to obtain a low refractive index layer. As a result, an optical film in which an antistatic hard coat layer and a low refractive index layer were formed in this order on a triacetyl cellulose substrate was produced.

<Examples 2-5 and Comparative Examples 1-8>
In Examples 2 and 3 and Comparative Examples 1 to 8, optical films were produced in the same manner as in Example 1 except that the antistatic hard coat layer compositions shown in Table 1 were used.

<Section observation of optical film>
The cross section of the optical film produced in Example 1 was photographed using a scanning transmission electron microscope (STEM) function of a scanning electron microscope (SEM) (S-4800, manufactured by Hitachi Kyowa Engineering Co., Ltd.). A STEM cross-sectional photograph was observed. FIG. 6 is a cross-sectional photograph of the optical film according to Example 1 taken using the scanning transmission electron microscope function of the scanning electron microscope. FIG. 7 is a cross-sectional photograph of the vicinity of the surface of the optical film of Example 1 taken using the scanning transmission electron microscope function of the scanning electron microscope.

  6 and 7, the first hard coat layer is present on the triacetyl cellulose substrate, and the second hard coat layer containing chain metal oxide particles is present on the first hard coat layer. It was confirmed that a low refractive index layer was present on the second hard coat layer. 6 and 7 confirm that there is no interface between the triacetyl cellulose substrate and the first hard coat layer and between the first hard coat layer and the second hard coat layer. did it.

<Evaluation of optical film>
The optical films produced in the above examples and comparative examples were evaluated by performing the following tests.

(Surface resistance measurement)
About each optical film produced by the said Example and comparative example, the surface resistance value was measured using the surface resistance value measuring device (High Lester HT-210, Mitsubishi Oil Chemical Co., Ltd. product).

(Total light transmittance measurement)
About each optical film produced by the said Example and comparative example, the total light transmittance was measured according to JISK-7361 using the haze meter (HM-150, Murakami Color Research Laboratory make).

(Haze value measurement)
About each optical film produced by the said Example and comparative example, the haze value was measured according to JISK-7361 using the haze meter (HM-150, Murakami Color Research Laboratory make).

(Reflection Y value measurement)
About each optical film produced by the said Example and comparative example, the reflection Y value was measured using the spectrophotometer (MCP3100, Shimadzu Corporation make). In the measurement of 5 ° regular reflectance for obtaining the reflection Y value, a black tape (manufactured by Teraoka Seisakusho) was pasted on the side opposite to the measurement film surface in order to prevent back reflection of the optical film.

(Pencil hardness test)
The pencil hardness test (4.9 N load) prescribed | regulated to JISK5600-5-4 (1999) was done with respect to the surface of the low-refractive-index layer of each optical film produced by the said Example and comparative example. The evaluation criteria were as follows.
○: No scratch / number of measurements = 4/5, 5/5
X: No scratch / number of measurements = 0/5, 1/5, 2/5, 3/5

(Interference fringe evaluation)
1. Visual evaluation A black tape was applied to the surface of the triacetylcellulose base material of each optical film produced in the above examples and comparative examples on the surface opposite to the surface on which the antistatic hard coat layer was formed. The presence or absence of interference fringes was evaluated visually. The evaluation criteria were as follows.
○: No interference fringes were confirmed.
X: Interference fringes were confirmed.

2. Spectral reflectance evaluation About each optical film produced by the said Example and comparative example, using a spectrophotometer (MCP3100, Shimadzu Corp. make), 5 degree regular reflectance was measured and the spectral reflectance curve was obtained. It was. Then, the presence or absence of ripples (maximum and minimum waves) in the spectral reflection curve was examined. In the measurement of 5 ° regular reflectance, a black tape (manufactured by Teraoka Seisakusho) was pasted on the side opposite to the measurement film surface in order to prevent back reflection of the optical film. The evaluation criteria were as follows.
○: Ripple was not confirmed or ripple was confirmed but very little.
X: Many ripples were confirmed.

(Adhesion evaluation)
About each optical film produced by the said Example and comparative example, the cross-cut adhesion test was done as adhesive evaluation, and the adhesion rate was computed. The cross-cut adhesion test was performed as follows. A 100 mm grid with a 1 mm square is put on the surface on the low refractive index layer side of the optical film, and a continuous peel test is performed 5 times using a 24 mm cello tape (registered trademark) manufactured by Nichiban Co., Ltd. The proportion of the squares (adhesion rate) was determined. The adhesion rate was calculated based on the following formula.
Adhesion rate (%) = (number of cells not peeled / total number of cells 100) × 100

(Evaluation of wear resistance of steel wool (SW))
Each optical film produced in the above-mentioned examples and comparative examples was # 0000 steel wool (trade name “BON STAR”, manufactured by Nippon Steel Wool Co., Ltd.), and a load of 300 g / cm ² was applied and a speed of 100 mm / sec. After rubbing 10 times, a black tape is applied to the surface of the triacetyl cellulose substrate opposite to the surface on which the antistatic hard coat layer is formed, and the presence or absence of scratches is visually evaluated under a three-wavelength fluorescent lamp. did. The evaluation criteria were as follows.
○: No scratch was confirmed.
X: Scratches were confirmed.

The evaluation results are shown in Table 1. In addition, “content of chain metal oxide particles (% by mass)” described in Table 1 means the content of chain metal oxide particles with respect to the total solid content of the composition for antistatic hard coat layer. It shall be.

  As shown in Table 1, the optical films of Examples 1 to 5 have a surface resistance value, total light transmittance, haze value, reflection Y value, pencil hardness, interference fringe resistance, adhesion, and SW wear resistance. The results satisfying all were obtained. In particular, regarding interference fringe prevention, it has been known that interference fringes generated at the interface between the hard coat layer and the light transparent substrate can be prevented by adding an appropriate amount of a permeable solvent to the hard coat composition. However, in the case of the antistatic hard coat layer, this permeable solvent alone was insufficient (see the result of the comparative example). This is because when an antistatic material such as antistatic fine particles is added, the antistatic material cannot penetrate into the light-transmitting substrate together with the penetrating solvent at a level capable of preventing interference fringes. This is considered to be because a new interface caused by the prevention material was generated between the antistatic hard coat layer and the light-transmitting substrate to form interference fringes. In contrast, in the present invention, since chain metal oxide particles are used for the antistatic material, it is considered that such an interface does not occur. For this reason, in the embodiments, good interference fringe prevention properties are obtained.

  On the other hand, the optical films of Comparative Examples 1 to 8 satisfy all of the surface resistance value, total light transmittance, haze value, reflection Y value, pencil hardness, interference fringe prevention property, adhesion, and SW wear resistance. It was not obtained. In Comparative Examples 1 and 2, since the functional group equivalent of urethane (meth) acrylate or polymer (meth) acrylate is too large, Comparative Examples 3 and 5 do not use a permeable solvent, and Comparative Example 6 uses urethane ( Since no (meth) acrylate or polymer (meth) acrylate is used, it is considered that either of the above performances could not be satisfied.

  The result of the surface resistance value in Comparative Example 7 is “over” in the optical film according to Comparative Example 7 because the amount of the non-chain antimony-doped tin oxide particles is small relative to the binder component. It is considered that this is because the distance between the particles is widened and the conductive path is not formed. Moreover, the result of the visual evaluation of the interference fringe prevention property in Comparative Example 7 is “◯”. In the optical film according to Comparative Example 7, the non-chain antimony-doped tin oxide particles are included in the amount of the binder component. On the other hand, since it is added in such an amount that the uniform dispersibility can be kept high, subsidence to the first hard coat layer side is almost eliminated although the specific gravity of the particles is higher than that of the binder component. This is thought to be due to the small change in the refractive index difference between the hard coat layer and the second hard coat layer. However, since the refractive index of the whole antistatic hard coat layer is larger than that of Comparative Example 6, “◯” in the visual evaluation of the three-wavelength fluorescent lamp of Comparative Example 7 is a level that can be used as a product. Compared with 6 “◯”, the level is bad. This shows that the result of the spectral reflectance evaluation for interference fringe prevention in Comparative Example 7 is “x”, which is also insufficient as interference fringe prevention.

Moreover, the result of the surface resistance value in Comparative Example 8 is 9 × 10 ⁹ because the amount of non-chain antimony-doped tin oxide particles in the optical film according to Comparative Example 8 is large. On the contrary, it is considered that this is because the interval between the particles is close and a sufficient conductive path is formed. Moreover, in the optical film according to Comparative Example 8, a large amount of non-chain antimony-doped tin oxide indicates that the results of visual evaluation and spectral reflectance evaluation of interference fringe prevention in Comparative Example 8 are “x”. The presence of the particles not only increases the refractive index of the antistatic hard coat layer, but also because the specific gravity of the particles is large, the particles sink into the first hard coat layer side, and the first hard coat layer This is probably because the difference in refractive index greatly changed at the interface between the first hard coat layer and the second hard coat layer.

DESCRIPTION OF SYMBOLS 1, 1A ... Light transmissive base material 2 ... Photocurable resin composition 3 for antistatic hard coat layer ... Mixed layer 4 ... Chain metal oxide particle content layer 5 ... First hard coat layer 6 ... Second Hard coat layer 7 ... Antistatic hard coat layer 8 ... Low refractive index layer 10 ... Optical film 20 ... Polarizing plate 21 ... Polarizing element 30 ... Image display device

Claims (12)

The surface of the light-transmitting substrate has at least six chain-shaped metal oxide particles composed of two or more conductive metal oxide particles linked in a chain, a photopolymerizable monomer, and a photopolymerizable functional group. Penetrating into the light transmissive substrate with at least one of urethane (meth) acrylate having a weight average molecular weight of 1000 or more and polymer (meth) acrylate having a weight average molecular weight of 10,000 or more having 10 or more photopolymerizable functional groups A photocurable resin composition for an antistatic hard coat layer containing a penetrating solvent having a property is applied and dried, and the main component of the light-transmitting substrate and the light are formed on the light-transmitting substrate. A mixed layer in which a polymerizable monomer is mixed is formed, and the chain metal oxide particles, the photopolymerizable monomer, the urethane (meth) acrylate, and the polymer are formed on the mixed layer. (Meth) forming a chain-like metal oxide particles-containing layer containing at least any of acrylate,
The mixed layer and the chain metal oxide particle-containing layer are cured by light irradiation, and a first hard coat layer that is a cured product of the mixed layer and a cured product of the chain metal oxide particle-containing layer And a step of forming an antistatic hard coat layer comprising a second hard coat layer formed on the first hard coat layer,
Content of the said chain | strand-shaped metal oxide particle with respect to the total solid of the said photocurable resin composition for antistatic hard-coat layers is 2-20 mass%, The manufacturing method of the optical film characterized by the above-mentioned.   The manufacturing method of the optical film of Claim 1 whose functional group equivalent of the said urethane (meth) acrylate and functional group equivalent of the said polymer (meth) acrylate are 150-500.   The manufacturing method of the optical film of Claim 1 or 2 which the said chain metal oxide particle consists of the said electroconductive metal oxide particle connected in the shape of 2-50 pieces. The conductive metal oxide particles are antimony-doped tin oxide, phosphorus-doped tin oxide, tin-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, ZnO, CeO ₂ , Sb ₂ O ₅ , SnO ₂ , In ₂ O ₃ , The method for producing an optical film according to claim 1, wherein the particles are metal oxide particles selected from the group consisting of Al ₂ O ₃ and Al ₂ O ₃ .   The method for producing an optical film according to any one of claims 1 to 4, wherein the light-transmitting substrate is a triacetylcellulose substrate. An optical film comprising a light transmissive substrate and an antistatic hard coat layer formed on the light transmissive substrate,
The antistatic hard coat layer comprises a first hard coat layer formed on the light transmissive substrate and a second hard coat layer formed on the first hard coat layer,
The first hard coat layer includes a main component of the light transmissive substrate and a first binder resin,
The second hard coat layer contains chain metal oxide particles composed of two or more conductive metal oxide particles linked in a chain and a second binder resin,
The second binder resin has a photopolymerizable monomer, a urethane (meth) acrylate having 6 or more photopolymerizable functional groups and a weight average molecular weight of 1000 or more, and a weight average molecular weight having 10 or more photopolymerizable functional groups. Includes a polymer with at least one of 10,000 or more polymer (meth) acrylates,
The refractive index of the first hard coat layer changes so as to gradually approach the refractive index of the light transmissive substrate from the second hard coat layer side toward the light transmissive substrate side. And there is no interface between the light-transmitting substrate and the first hard coat layer and between the first hard coat layer and the second hard coat layer. the film.   The optical film of Claim 6 whose functional group equivalent of the said urethane (meth) acrylate and functional group equivalent of the said polymer (meth) acrylate are 150-500.   The optical film according to claim 6 or 7, wherein the chain metal oxide particles are composed of 2 to 50 conductive metal oxide particles connected in a chain. The conductive metal oxide particles are antimony-doped tin oxide, phosphorus-doped tin oxide, tin-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, ZnO, CeO ₂ , Sb ₂ O ₅ , SnO ₂ , In ₂ O ₃ , The optical film according to claim 6, wherein the optical film is a metal oxide particle selected from the group consisting of Al ₂ O ₃ .   The optical film according to claim 6, wherein the light transmissive substrate is a triacetyl cellulose substrate. The optical film according to any one of claims 6 to 10,
A polarizing plate comprising: a polarizing element formed on a surface opposite to a surface on which the first hard coat layer is formed in the light transmissive substrate of the optical film.   An image display device comprising the optical film according to claim 6 or the polarizing plate according to claim 11.