JP5842320B2 - Manufacturing method of optical film, optical film, polarizing plate, and image display device - Google Patents

Description

  The present invention relates to an optical film manufacturing method used for the purpose of protecting the surface of an image display device or the like, an optical film, a polarizing plate including the optical film, and an image display device.

The image display surface of an image display device such as a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence (EL) display device, a projection display, a cold cathode tube (CRT) display device, or a reflective screen is scratched during handling. It is required to impart hardness (abrasion resistance) so as not to stick.
On the other hand, by using an HC film or an optical film provided with a hard coat (hereinafter sometimes simply referred to as “HC”) layer on a base material on an image display surface of the image display device, an image of the image display device is obtained. Generally, the hardness of the display surface is improved.

  The HC layer in which only the binder component is cured often has insufficient hardness, and in addition to the binder component, a composition containing reactive inorganic fine particles having reactive groups on the particle surface such as silica fine particles is cured to cure HC. Generally, the hardness of an HC film or an optical film is improved by forming a layer (for example, Patent Document 1).

In addition, when an HC film or an optical film is bonded to one side of a polarizing element to produce a polarizing plate, the HC film or the optical film is immersed in an alkaline solution, and the surface of the HC film or the optical film on the substrate side A process for hydrophilizing (hereinafter referred to as “saponification process”) is performed.
However, the silica fine particles contained on the HC surface have the property of easily falling off the HC layer by saponification treatment or easily flowing out or dissolving in an alkaline solution. If the silica fine particles fall off from the HC layer, the content of the silica fine particles is reduced, so that a desired hardness cannot be obtained. Another problem is that the silica solution is contaminated when the silica particles flow out or dissolve in the alkali solution.

  On the other hand, a method is considered in which two HC layers are laminated so that the silica particles are contained only in the lower HC layer, and the binder component is cured without containing the silica particles in the upper (surface) HC layer. It is done.

  However, in the case of laminating two HC layers, the composition to be the lower HC layer is applied to the base material, and the coating film is irradiated with light to be sufficiently cured to form the lower HC layer. A method of applying an upper HC layer composition on the upper layer and irradiating the coating film with light to sufficiently cure it to form an upper HC layer (hereinafter simply referred to as “sequential coating method”). However, there is a problem that a clear layer interface is formed between the upper and lower layers, interference fringes are generated by the layer interface, and the appearance of the optical film and the HC film is impaired.

  In contrast to the sequential coating method in which the upper and lower layers are sequentially and completely cured, the light irradiation amount on the lower layer is suppressed and semi-cured (half cure), and then the upper layer is formed on the semi-cured lower layer. A method of applying the composition and completely curing (full curing) the upper coating film together with the semi-cured lower layer (hereinafter simply referred to as “half-curing method”) is also conceivable.

  However, even with this half-curing method, the interface between the upper and lower layers cannot be completely eliminated, and a layer interface is formed, and interference fringes are generated by the layer interface, thereby deteriorating the appearance of the optical film and the HC film.

  Further, in this half cure method, since the coating and light irradiation steps are performed a plurality of times, the steps become complicated, the productivity is not high, and the manufacturing cost increases.

In contrast, in Patent Document 2, simultaneous multilayer coating (hereinafter also referred to as “simultaneous coating”) is performed in order to provide an optical film capable of preventing the occurrence of interference fringes and a method for manufacturing the same. Yes.
However, this Patent Document 2 has no attention regarding saponification resistance. Moreover, in this patent document 2, it is a layer structure of a base material / hard coat layer / high refractive index gradient hard coat layer / low refractive index layer, and in the high refractive index gradient hard coat layer, mainly diffusion of high refractive index fine particles. Due to sedimentation, the refractive index is inclined such that the closer to the lower hard coat layer side, the lower the refractive index, and the closer to the upper lower refractive index layer side, the higher the refractive index. That is, in the high refractive index gradient hard coat layer, the amount of high refractive index fine particles increases as it is closer to the upper lower refractive index layer side, and the amount of high refractive index fine particles decreases as it is closer to the lower hard coat layer side. It is. For this reason, in Patent Document 2, there is no description of a form in which the silica fine particles are distributed more as it is closer to the lower layer side and the silica fine particle distribution is less as it is closer to the upper layer side and a method therefor in the HC layer by the simultaneous coating method.

  For these reasons, there is a demand for an optical film excellent in hardness and saponification resistance, free from interference fringes, good in appearance, and excellent in productivity, and a method for producing the optical film.

JP 2008-165041 A JP 2009-265658 A

  The present invention has been made in order to solve the above problems, and has excellent hardness and saponification resistance, no interference fringes, good appearance, and a method for producing an optical film excellent in productivity. An object is to provide an optical film, a polarizing plate including the optical film, and an image display device.

As a result of intensive studies by the present inventors, in the simultaneous coating method, it is possible to simply include silica fine particles in the lower composition, and to include the binder component without including the silica fine particles in the upper composition. It has been found that sufficient saponification resistance cannot be obtained, and furthermore, uneven lines (hereinafter referred to as “coating lines”) are generated in the HC layer and the appearance is impaired.
Therefore, as a result of further diligent investigations by the present inventors, in the simultaneous coating method in which silica fine particles are contained in the lower composition, and the binder component is contained in the upper composition without containing the silica fine particles. Found that the viscosity of the composition on the upper side and the lower side affects the control of the distribution of silica fine particles and the occurrence of coating stripes, and the viscosity of the composition on the upper side and the lower side is within a specific range. As a result, it was found that an optical film having excellent hardness and saponification resistance, no interference fringes and coating stripes, good appearance, and high productivity was obtained, and the present invention was completed.

That is, the method for producing an optical film according to the present invention includes (i) a step of preparing a light-transmitting resin substrate, and (ii) each having photocurability or thermosetting between the same and different reactive groups. A reactive group comprising a reactive silica fine particle having an average primary particle size of 1 nm to 100 nm having a reactive group on the particle surface, a first binder component having a reactive group, and a first solvent, and having a viscosity The second curable resin composition for hard coat layer having a reactive group of 5 mPa · s or more and 9.5 mPa · s or less , the second binder component having a reactive group, and the second binder component not containing the reactive silica fine particles includes a solvent, preparing a second hard coat layer curable resin composition viscosity is less 10 mPa · s or more 30.5mPa · s, and, (iii) one surface side of the light transmitting resin substrate And the light-transmitting resin A step of coating the first curable resin composition for a hard coat layer and the second curable resin composition for a hard coat layer simultaneously from the material side to form a coating film, (iv) and iii) curing the coating film obtained in the step by light irradiation and / or heating to form a hard coat layer.

First curable resin composition for hard coat layer (hereinafter also simply referred to as “first composition”) and second curable resin composition for hard coat layer (hereinafter simply referred to as “second composition”) In each case, by setting the viscosity within the above specific range, it is possible to moderately mix the contact portions of the two compositions while preventing the entire two compositions from being mixed when applied simultaneously. To do. And in order to cure while maintaining the composition of the two compositions while mixing appropriately at the contact portion in this way, the interface does not occur in the HC layer, the occurrence of interference fringes is suppressed, and the appearance of the optical film is good It can be. Moreover, since the viscosity of a 1st composition and a 2nd composition is moderate, and two whole compositions do not mix, a coating stripe does not arise in a cured film and an external appearance becomes favorable.
Further, only the first composition that cures to form the lower side of the HC layer contains reactive silica fine particles, and the second composition that cures to form the upper side of the HC layer includes the reactive silica. Does not contain fine particles. And since the whole two compositions are not mixed by the simultaneous application, even if the saponification treatment is performed on the optical film including the HC layer formed by the simultaneous application using such two compositions, Since there are few silica microparticles | fine-particles on the side, the outflow and dropping-out of a silica microparticle are suppressed. Therefore, the optical film is excellent in saponification resistance.
Note that the upper side and the lower side of the HC layer mean a relative positional relationship with respect to each other, and do not mean absolute positions such as the upper half and the lower half of the HC layer.
In this invention, the layer interface in a hard-coat layer means the interface which can be visually recognized in the observation using the TEM (transmission electron microscope) of the cross section of the film thickness direction of an optical film.

In the method for producing an optical film according to the present invention, the light-transmitting resin substrate is a triacetyl cellulose substrate, and the first curable resin composition for a hard coat layer is based on the total mass of the first solvent. The ratio of methyl ethyl ketone can be 50% by mass or more.

  One aspect of the optical film according to the present invention is obtained by the above-described method for producing an optical film.

Another aspect of the optical film according to the present invention is an optical film in which at least a hard coat layer is provided on one side of a light-transmitting resin substrate, and the hard coat layer has an average primary particle size. include 100nm or less of the silica fine particles or 1 nm, in the hard coat layer, the thickness direction of the hard coat layer, the abundance of the silica fine particles are close to the surface opposite to the said light transmissive resin substrate In the hard coat layer, less than 90% of the total amount of the silica fine particles is present in the region from the light transmissive resin substrate to 70% of the film thickness of the hard coat layer, and the light transmissive 90% or more of the total amount of the silica fine particles is present in a region from the resin substrate to 75% of the film thickness of the hard coat layer .

In another aspect of the optical film according to the present invention, the surface of the hard coat layer opposite to the light-transmitting resin substrate is further opposite to the surface of the hard coat layer opposite to the light-transmitting resin substrate. A low refractive index layer having a lower refractive index than the interface , or a high refractive index layer having a higher refractive index than the interface opposite to the light-transmitting resin substrate of the hard coat layer from the hard coat layer side, and the hard coat A low refractive index layer having a lower refractive index than the interface of the layer opposite to the light-transmitting resin substrate may be provided.

  The polarizing plate according to the present invention is characterized in that the optical film is disposed on one surface side of the polarizing element, and the light transmissive resin substrate side of the optical film is directed toward the polarizing element.

  An image display device according to the present invention includes the optical film.

In the HC layer, the optical film according to the present invention is excellent in appearance because generation of coating lines and interference fringes is suppressed. In the HC layer, in the film thickness direction of the HC layer, the closer the silica fine particles are to the interface opposite to the light-transmitting resin base material, the more the silica fine particles are prevented from flowing out and dropping off. The optical film is excellent in saponification resistance. Furthermore, the process and cost of providing a protective film in order to prevent the silica fine particles from flowing out or falling off during the saponification treatment of the optical film become unnecessary.
According to the method for producing an optical film of the present invention, since the HC layer is formed by simultaneous application using the two compositions having the specific viscosity described above, the hardness and saponification resistance are excellent, and interference fringes are formed. In addition, an optical film having no appearance of coating lines and good appearance can be easily obtained with high productivity.

FIG. 1 is a schematic view showing an example of the simultaneous application in step (iii) in the method for producing an optical film according to the present invention. FIG. 2 is a schematic view showing an example of the layer structure of the optical film according to the present invention. FIG. 3 is a schematic view showing another example of the layer structure of the optical film according to the present invention. FIG. 4 is a schematic view showing another example of the layer structure of the optical film according to the present invention. FIG. 5 is a cross-sectional view schematically showing an example of a state of distribution of silica fine particles in the hard coat layer of the optical film according to the present invention. FIG. 6 is a schematic diagram showing an example of the configuration of the polarizing plate according to the present invention.

According to the definition of film and sheet in JIS K6900, the sheet is thin and generally refers to a flat product whose thickness is small relative to the length and width, and the film is extremely small compared to the length and width. A thin, flat product with an arbitrarily limited maximum thickness, usually supplied in the form of a roll. Therefore, it can be said that a film having a particularly thin thickness among the sheets is a film, but the boundary between the sheet and the film is not clear and is difficult to distinguish clearly. Therefore, in the present invention, the meaning of both a thick sheet and a thin sheet is meant. Including “” is defined as “film”.
In the present invention, the “hard coat layer” refers to a layer having a hardness of “H” or higher in a pencil hardness test (4.9 N load) defined in JIS K5600-5-4 (1999).
In the present invention, (meth) acrylate represents acrylate and / or methacrylate.
The average primary particle diameter of the fine particles means a 50% particle diameter (d50 median diameter) when the fine particles in the solution are measured by a dynamic light scattering method and the particle size distribution is represented by a cumulative distribution. The average primary particle size can be measured using a Microtrac particle size analyzer manufactured by Nikkiso Co., Ltd.
The light of the present invention includes not only electromagnetic waves having wavelengths in the visible region and invisible region, but also particle beams such as electron beams, and radiation or ionizing radiation that collectively refers to electromagnetic waves and particle beams.
In the present invention, unless otherwise specified, the film thickness means the film thickness during drying (dry film thickness).
In the present invention, the molecular weight means a weight average molecular weight which is a polystyrene equivalent value measured by gel permeation chromatography (GPC) when having a molecular weight distribution, and when having no molecular weight distribution, Mean molecular weight.
In the present invention, the term “spherical” is a concept including not only a true sphere but also a shape that can be approximated to a sphere including a substantially spherical shape, a spheroid, and a polyhedron.
In the present invention, the refractive index is measured using a spectrophotometer (UV-3100PC, manufactured by Shimadzu Corporation), the absolute reflectance at a wavelength of 380 to 780 nm, and a simulation is performed from the obtained reflectance curve. Means the refractive index value obtained by
In the present invention, the surface resistance value is a value measured using a surface resistivity meter (trade name: Hiresta IP MCP-HT260, manufactured by Mitsubishi Chemical Corporation).
In the present invention, the dry film thickness is a value measured using trade name IDF-130 manufactured by Mitutoyo Corporation.

  Hereinafter, the manufacturing method of the optical film according to the present invention will be described first, and then the optical film, the polarizing plate and the image display device will be described.

(Optical film manufacturing method)
The method for producing an optical film according to the present invention includes (i) a step of preparing a light-transmitting resin substrate, and (ii) a reactivity having photocurability or thermosetting properties between the same and different reactive groups, respectively. A reactive silica fine particle having an average primary particle diameter of 1 to 100 nm having a reactive group on the particle surface, a first binder component having a reactive group and a first solvent, and having a viscosity of 3 to 100 mPa -The s 1st curable resin composition for hard coat layer and the reactive silica fine particles are not included, the second binder component having a reactive group and the second solvent are included, and the viscosity is 10 to 100 mPa. a step of preparing a second curable resin composition for a hard coat layer that is s, (iii) on the one surface side of the light transmissive resin substrate, from the light transmissive resin substrate side, the first Curable resin composition for hard coat layer and A step of simultaneously applying the second curable resin composition for a hard coat layer to form a coating film, and (iv) curing the coating film obtained in the step (iii) by light irradiation and / or heating. And a step of forming a hard coat layer.

By making each of the viscosity of the first composition and the second composition within the specific ranges described above, it is possible to prevent the two compositions from being mixed when applied at the same time, but to contact the two compositions. Mix the parts moderately. And in order to cure while maintaining the composition of the two compositions while mixing appropriately at the contact portion in this way, the interface does not occur in the HC layer, the occurrence of interference fringes is suppressed, and the appearance of the optical film is good It can be. Moreover, since the viscosity of a 1st composition and a 2nd composition is moderate, and two whole compositions do not mix, a coating stripe does not arise in a cured film and an external appearance becomes favorable.
Further, only the first composition that cures to form the lower side of the HC layer contains reactive silica fine particles, and the second composition that cures to form the upper side of the HC layer includes the reactive silica. Does not contain fine particles. And since the whole two compositions are not mixed by the simultaneous application, even if the saponification treatment is performed on the optical film including the HC layer formed by the simultaneous application using such two compositions, Since there are few silica microparticles | fine-particles on the side, the outflow and dropping-out of a silica microparticle are suppressed. Therefore, the optical film is excellent in saponification resistance.

  In addition, by appropriately selecting the components contained in the first composition and the second composition, it is possible to express different functions on the upper side and the lower side of the HC layer.

  Hereinafter, each process of (i)-(iv) of the manufacturing method of the optical film which concerns on this invention is demonstrated in order.

((I) Process)
In the step (i), a light transmissive resin base material is prepared.
(Light transmissive resin substrate)
The light-transmitting resin base material used in the present invention is a plastic film having high light transmittance, and a conventionally known hard coat film, a light-transmitting resin base material or a transparent resin base material of an optical film is appropriately selected and used. be able to.
The average light transmittance of the light transmissive resin substrate is preferably 70% or more, and more preferably 85% or more. In addition, the measurement of light transmittance uses the value measured in room temperature and air | atmosphere using the ultraviolet visible spectrophotometer (For example, brand name UV-3100PC made from Shimadzu Corporation).

  In the present invention, the thickness of the light transmissive resin substrate can be appropriately selected and used. Usually, the thickness of the light-transmitting substrate is 10 to 300 μm, but it is preferably 40 to 200 μm from the viewpoint of hardly cracking the surface of the optical film and imparting hardness.

  Preferable materials for the light-transmitting resin substrate include triacetyl cellulose (TAC), cycloolefin polymer, polycarbonate, acrylate polymer, or polyester such as polyethylene terephthalate (PET). Here, “mainly” means a component having the highest content ratio among the constituent components of the base material.

As the light-transmitting resin base material used in the present invention, TAC is preferably used from the viewpoint of being most excellent in light transmittance.
TAC is a light-transmitting resin substrate that can have an average light transmittance of 50% or more in a visible light region of 380 to 780 nm.
Since TAC has optical isotropy, it can be preferably used for LCD applications.

  In the present invention, a surface treatment (for example, saponification treatment, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment) may be applied to the light-transmitting resin substrate, and a primer layer (adhesive layer) ) May be formed. The light-transmitting resin substrate in the present invention refers to those including these surface treatments and primer layers.

(Step (ii))
In the step (ii), a first composition and a second composition having a specific viscosity are prepared.
Either step (i) or step (ii) may be performed first or simultaneously.
Hereinafter, the first composition and the second composition will be described.

(First curable resin composition for hard coat layer)
The first composition includes reactive silica fine particles having an average primary particle diameter of 1 to 100 nm having a reactive group on the particle surface, a first binder component having a reactive group, and a first solvent, and has a viscosity of 3 ˜100 mPa · s.

The viscosity of the first composition is 3 to 100 mPa · s. When the coating film formed by simultaneous coating is cured, the reactive silica fine particles contained in the first composition move, such as diffusion and floating. From the viewpoint of controlling the viscosity, it is preferably 3 to 50 mPa · s, more preferably 5 to 30 mPa · s.
In the method for producing an optical film according to the present invention, the absolute value of the difference between the viscosity of the first composition and the viscosity of the second composition described later is preferably 30 or less. When this absolute value is 30 or less, when the coating film formed by simultaneous coating is cured, the movement of the reactive silica fine particles contained in the first composition, such as diffusion and floating, is controlled, and the coating film It is easy to control the distribution of silica fine particles in the cured HC layer. The absolute value is preferably 30 or less, and more preferably 1 to 15.
The viscosity of the first composition and the viscosity of the second composition described below are 3 to 100 mPa · s and 10 to 100 mPa · s, respectively, but the viscosity of the first composition is 5 to 30 mPa · s, And it is more preferable that the viscosity of a 2nd composition is 20-30 mPa * s.
Furthermore, it is preferable that the viscosity of the second composition is larger than the viscosity of the first composition because the degree of mixing of the first composition and the second composition can be easily controlled and the productivity is excellent.

(Reactive silica fine particles)
The reactive silica fine particles are silica fine particles having a reactive group on the particle surface.
The reactive group is a group having photocurability or thermosetting such as polymerization or cross-linking by light irradiation or heating between the same or different reactive groups. The reactive group of the reactive silica fine particles and the reactive group of the first binder described later react by polymerization or crosslinking to impart hardness to the HC layer.
When the reactive group is a photocurable group, the photocurable group is preferably a photocurable unsaturated group, and particularly preferably an ionizing radiation curable unsaturated group. Specific examples thereof include an ethylenically unsaturated bond such as a (meth) acryloyl group, a (meth) acryloyloxy group, a vinyl group and an allyl group, and an epoxy group.
When the reactive group is a thermosetting group, examples of the thermosetting group include a hydroxyl group, a carboxyl group, an amino group, an epoxy group, a glycidyl group, an isocyanate group, and an alkoxyl group.
The reactive silica fine particles, the first binder component, and the reactive groups contained in the second binder component contained in the second composition to be described later may be the same as long as they are capable of curing reaction with each other. May be different. Further, the reactive silica fine particles, the reactive group possessed by the first binder component and the second binder component may be a photocurable group alone, a thermosetting group alone, Both a curable group and a thermosetting group may be used.

The reactive silica fine particles have an average primary particle size of 1 to 100 nm, preferably 10 to 80 nm, and more preferably 12 to 50 nm. If the average primary particle size is less than 1 nm, sufficient hardness cannot be imparted to the HC layer. When the average primary particle size exceeds 100 nm, the haze of the HC layer increases.
The reactive silica fine particles may be used alone or in combination with different average primary particle diameters. When using in combination of 2 or more types, each average primary particle diameter should just be 1-100 nm.

  The particle shape of the reactive silica fine particles is not particularly limited, and may be appropriately selected from conventionally known shapes according to required performance such as hardness and transparency. Examples of the shape of the particles include a spherical shape, a needle shape, and a chain shape in which the spherical particles are connected. The irregular shaped silica fine particles (chain particles) described in JP 2010-120182 A, which are formed by combining 3 to 20 silica fine particles by an inorganic chemical bond, are preferable because they can impart excellent hardness to the HC layer.

  What is necessary is just to adjust suitably content of the reactive silica fine particle in a 1st composition from viewpoints, such as hardness and a haze. For example, the content ratio of the reactive silica fine particles is preferably 15 to 70% by mass, more preferably 35 to 65% by mass, and further preferably 50 to 65% by mass with respect to the total solid content of the first composition. If the said content rate is 15 mass% or more, it will be easy to provide the hardness which was excellent in HC layer. If the said content rate is 70 mass% or less, the adhesiveness of a silica particle and a 1st binder component will be maintained, and the hardness of HC layer will fully be raised.

  The reactive silica fine particles may be prepared by a conventionally known method. For example, a preparation method by surface adsorbed ion removal and subsequent surface treatment described in Patent Document 1 may be used.

(First binder component)
The first binder component is a component that has a reactive group and cures to become a matrix of the HC layer.
In the present invention, the first composition is not mixed as a whole with the second composition described later, but is appropriately mixed at the portion where the two compositions are in contact. Therefore, the first binder component can react with the second binder component contained in the second composition to be described later due to the reactive group, such as polymerization or crosslinking, and the first binder component mainly in the HC layer. It also has the function of enhancing the adhesion between the lower side where the composition is cured and the upper side where the second composition is cured.

As the first binder component, a binder component such as a conventionally known monomer, oligomer or polymer having a reactive group having photo-curing property or thermosetting property such as polymerization or crosslinking by light irradiation or heating between reactive groups is used. Can be used. The first binder component is a monomer having a reactive group,
Examples of the binder component having a photocurable group as a reactive group include monofunctional (meth) acrylate, di (meth) acrylate, tri (meth) acrylate and polyfunctional (meta) described in JP-A-2004-300210. ) Derivatives such as acrylates and EO-modified products thereof, oligomers obtained by polymerizing these radical polymerizable monomers, and polymers having an ethylenically unsaturated bond. Moreover, the 1st photocurable resin described in patent document 1, the 2nd photocurable resin, what has the acrylate-type functional group described in patent document 2, etc. can be used.
Examples of the thermosetting binder component include a compound having an epoxy group and a binder epoxy compound described in JP-A-2006-106503. Moreover, the thermosetting resin of patent document 1 can be used.
Further, a non-reactive binder component that solidifies by drying or cooling without being sensitive to light and heat may be used in combination without departing from the gist of the present invention.
Examples of the non-reactive binder component include polyacrylic acid, polyimide, and polyvinyl alcohol described in JP-A-2004-300210.
A 1st binder component may be used individually by 1 type, and may be used in combination of 2 or more type.
What is necessary is just to adjust suitably content of the 1st binder component in a 1st composition according to the molecular weight of a 1st binder component, the number of reactive groups, the applicability | paintability requested | required, etc. The viewpoint that the first binder component is contained by 20 to 95% by mass with respect to the remainder obtained by removing the reactive silica fine particles from the total solid content of the first composition to form a matrix of the HC layer by curing. To preferred.

(First solvent)
The first solvent has a function of adjusting the viscosity of the first composition and imparting coatability to the first composition.
The first solvent can be used without particular limitation as long as it is a conventionally known hard coat film or optical film.
Examples of the first solvent include alcohols, ketones, esters, halogenated hydrocarbons, and aromatic hydrocarbons described in JP-A-2005-316428.

In order to prevent the occurrence of interference fringes, it is preferable to use a solvent that is permeable to the light-transmitting resin substrate (hereinafter simply referred to as “permeable solvent”).
In the present invention, penetrability means not only the property of penetrating the light transmissive resin base material but also the concept of swelling or wetting the light transmissive resin base material.
Specific examples of the penetrating solvent include alcohols such as isopropyl alcohol, methanol and ethanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as methyl acetate, ethyl acetate and butyl acetate, halogenated hydrocarbons, Aromatic hydrocarbons such as toluene and xylene, and phenols can be mentioned.
Examples of the solvent used when the light transmissive substrate is TAC and the solvent used when the light transmissive substrate is PET include the solvents described in JP-A-2005-316428.
In particular, when the light-transmitting substrate is TAC, the solvent used is preferably methyl acetate, ethyl acetate, butyl acetate or methyl ethyl ketone.
The solvent used when the light-transmitting substrate is PET is preferably phenol, chlorobenzene, nitrobenzene, chlorophenol and hexafluoroisopropanol.
In addition to penetrability, the ketone solvent can easily and uniformly apply the first composition to the surface of the light-transmitting substrate, and the evaporation rate of the solvent after application is moderate. It has an effect that it is difficult to cause uneven drying. For this reason, a large-area coating film having a uniform thickness can be easily obtained.
As the first solvent, the above solvents may be used alone or in combination of two or more.
The amount of the first solvent may be such that the viscosity of the first composition is 3 to 100 mPa · s.
When using a combination of a permeable solvent and a non-permeable solvent as the first solvent, the proportion of the permeable solvent is preferably 50% by mass or more based on the total mass of the first solvent, and is 80% by mass. More preferably.

(Other components of the first composition)
In the first composition, within the range not departing from the gist of the present invention, the curing of the component having a reactive group such as the first binder component, the viscosity adjustment of the first composition, the hardness to the HC layer, For the purpose of imparting antistatic properties and the like, other components such as a photopolymerization initiator, a curing agent, a thickener, an antistatic agent and a leveling agent may be contained.

(Photopolymerization initiator)
The photopolymerization initiator has a function of accelerating the curing of the component having the photocurable group when the reactive group is a photocurable group.
As the photopolymerization initiator, for example, photoinitiators such as acetophenones and benzophenones described in JP-A-2007-272132 can be used.
Among them, 1-hydroxycyclohexyl phenyl ketone (trade name Irgacure 184 manufactured by Ciba Specialty Chemicals Co., Ltd.) and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one ( Ciba Specialty Chemicals Co., Ltd. trade name Irgacure 907) is preferably used in the present invention because it initiates and accelerates the photopolymerization reaction even in a small amount.
A photoinitiator may be used individually by 1 type and may be used in combination of 2 or more type.
When using a photoinitiator, it is preferable to use it so that the content may become 0.1-20 mass% with respect to the total solid of a 1st composition.

(Curing agent)
When the reactive group is a thermosetting group, the curing agent has a function of promoting the curing of the component having the thermosetting group.
As such a curing agent, a curing agent used in combination with a conventionally known thermosetting binder may be used. For example, many curing agents such as phthalic anhydride and trimellitic anhydride described in JP-A No. 2006-284752 may be used. A polyvalent carboxylic acid such as a polyvalent carboxylic acid anhydride or succinic acid or trimellitic acid can be used.
A hardening | curing agent may be used individually by 1 type, and may be used in combination of 2 or more type.
When using a hardening | curing agent, 1-100 mass parts is preferable with respect to 100 mass parts of binder components which have a thermosetting group, and 5-50 mass parts is more preferable.

(Thickener)
The first composition may contain a thickener of an organic compound and / or an inorganic compound for the purpose of adjusting the viscosity.
Examples of organic compound thickeners include, for example, ethyl cellulose, hydroxypropyl cellulose, acrylic resin, fatty acid amide wax, polyethylene oxide, amine salt of high molecular polyester, salt of linear polyaminoamide and high molecular acid polyester, amide of polycarponic acid Examples thereof include solutions, alkyl sulfonates, alkyl allyl sulfonates, colloidal esters, polyester resins, phenol resins, melamine resins, epoxy resins, urethane resins and polyimide resins, and those obtained by pulverizing them.
Examples of thickening agents for inorganic compounds include calcium stearate, zinc stearate, aluminum stearate, aluminum oxide, zinc oxide, magnesium oxide, glass, diatomaceous earth, titanium oxide, zirconium oxide, silicon dioxide, talc, mica, Feldspar, kaolinite (kaolin clay), pyrophyllite (waxite clay), sericite (sericite), bentonite, smectite vermiculites (montmorillonite, beidellite, nontronite, saponite, etc.), organic bentonite and organic smectite, etc. Is mentioned.
A commercially available product may be used as the thickener. Commercially available organic compound thickeners include, for example, Selney HPC-H, HPC-M, HPC-L, HPC-SL and HPC-SSL manufactured by Nippon Soda Co., Ltd., diamond manufactured by Mitsubishi Rayon Co., Ltd. NAR BR series, Disparon # 6900-20X, Disparon # 4200, Disparon KS-873N and Disparon # 1850 manufactured by Enomoto Kasei Co., Ltd. BYK-405 and BYK-410 manufactured by Big Chemie Japan, Rohm and Primal RW-12W manufactured by Haas, AS-AT-20S, AS-AT-350F, AS-AD-10A, AS-AD-160, etc. manufactured by Ito Oil Co., Ltd. It is done.
Commercially available inorganic compound thickeners include, for example, Shiraishi Kogyo Co., Ltd. Crown clay, Burgess clay # 60, Burgess clay KF and Opti White, Kaolin JP-100, NN Kaolin clay, manufactured by Tsuchiya Kaolin Kogyo Co., Ltd. ST kaolin clay and hard sill, Angel Hard Co., Ltd. ASP-072, Satinton Plus, Translink 37 and Hydras Delami NCD, Maruo Calcium Co., Ltd. SY Kaolin, OS clay, HA clay and MC hard clay, Lucentite SWN, Lucentite SAN, Lucentite STN, Lucentite SEN and Lucentite SPN manufactured by Co-op Chemical Co., Smecton manufactured by Kunimine Industry Co., Ltd. And Olga Knight T, Wilbur-Ellis Co. Hotaka indicia, Orben, 250M, Benton 34 and Bentone 38, Nippon Silica Industrial Co., Ltd. Laponite include Laponite RD and Laponite RDS, and the like.
From the viewpoint of transparency, preferred thickeners are the organic compound thickeners, among which hydroxypropylcellulose and acrylic resins are preferred.
A thickener may be used individually by 1 type and may be used in combination of 2 or more type.
In the manufacturing method of the optical film which concerns on this invention, it is preferable that a 1st composition and / or a 2nd composition contain a thickener. When using a thickener, it is preferable that the content will be 0.1-10 mass% with respect to the total solid of a 1st composition.
When a thickener is contained in the first composition and the second composition, the thickeners of the first composition and the second composition may be the same or different. .

(Antistatic agent)
The antistatic agent is a component for imparting antistatic properties to the HC layer.
An antistatic agent is not specifically limited, A conventionally well-known thing can be used.
Examples of the antistatic agent include an anionic antistatic agent, a cationic antistatic agent, an amphoteric antistatic agent, a nonionic antistatic agent, an electrolyte, and an ionic liquid described in JP-A-2009-265658. Is mentioned.
An antistatic agent may be used individually by 1 type, and may be used in combination of 2 or more type.
The content of the antistatic agent is not particularly limited and may be appropriately adjusted and used. For example, the surface resistivity of the HC layer is preferably 1.0 × 10 ¹³ Ω / □ or less, and more preferably 1.0 × 10 ⁸ Ω / □ or less. May be used in such a range.

(Leveling agent)
The leveling agent has a function of imparting antifouling property, coating property or smoothness to the surface of the HC layer when it is formed.
As the leveling agent, there can be used fluorine-based, silicone-based, acrylic-based leveling agents and the like used in conventionally known antireflection films and optical films. For example, a leveling agent having no ionizing radiation curable group such as a trade name “Megafac Series” (MCF350-5) manufactured by DIC Corporation, or an ionizing radiation such as a trade name “X-22-163A” manufactured by Shin-Etsu Chemical Co., Ltd. Any leveling agent having a curable group can be used.
Fluorine and silicone leveling agents also have antifouling properties.
A leveling agent may be used individually by 1 type, and may be used in combination of 2 or more type.
When a leveling agent is used, the content is preferably 5.0% by mass or less, more preferably 0.1 to 3.0% by mass with respect to the mass of the first binder component. preferable.

(Second curable resin composition for hard coat layer)
The second composition does not include the reactive silica fine particles, includes the second binder component and the second solvent, and has a viscosity of 10 to 100 mPa · s.
When the second composition does not contain the reactive silica fine particles and the viscosity of the first composition and the viscosity of the second composition are in the specific range, the upper side of the HC layer formed by simultaneous application In addition, since the amount of silica fine particles after the reaction of the reactive silica fine particles is small, the optical film is excellent in saponification resistance.

  The viscosity of the second composition is 10 to 100 mPa · s, but when the coating film formed by simultaneous coating is cured, the reactive silica fine particles contained in the first composition are diffused, floated, etc. From the viewpoint of controlling movement, it is preferably 15 to 50 mPa · s, and more preferably 20 to 30 mPa · s.

(Second binder component)
The second binder component is a component that has a reactive group and cures to become a matrix of the HC layer.
As the second binder component, those described in the first binder component can be used.
A 2nd binder component may be used individually by 1 type, and may be used in combination of 2 or more type.
The second binder component and the first binder component may be the same or different in kind, molecular weight, number of reactive groups, and the like.
What is necessary is just to adjust suitably content of the 2nd binder component in a 2nd composition according to the molecular weight of a 2nd binder component, the number of reactive group groups, the applicability | paintability requested | required. When the second binder component does not contain the high refractive index fine particles described later, it is preferably contained in an amount of 20 to 95% by mass with respect to the total solid content of the second composition. When it is contained, it is preferably contained in an amount of 20 to 95% by mass with respect to the remainder obtained by removing the high refractive index fine particles from the total solid content of the second composition from the viewpoint of curing and forming a matrix of the HC layer.

(Second solvent)
The second solvent has a function of adjusting the viscosity of the second composition.
As the second solvent, those described for the first solvent can be used.
A 2nd solvent may be used individually by 1 type, and may be used in combination of 2 or more type.
The second solvent and the first solvent may be the same or different.
The amount of the second solvent may be such that the viscosity of the second composition is 10 to 100 mPa · s.

(Other components of the second composition)
In the second composition, within the range not departing from the gist of the present invention, the curing of the component having a reactive group such as the second binder component, the viscosity adjustment of the second composition, the hardness to the HC layer, Other components such as photopolymerization initiators, thickeners, lubricants, antistatic agents, antifouling agents, and leveling agents are included for the purpose of imparting antistatic properties, antifouling properties, blocking resistance, etc. Also good.
As the photopolymerization initiator, thickener, antistatic agent and leveling agent, those described in the first composition can be used.

(Anti-fouling agent)
The antifouling agent prevents the outermost surface of the optical film from being stained, and can also impart scratch resistance to the HC layer.
As the antifouling agent, a conventionally known antifouling agent (antifouling agent) such as a fluorine compound or a silicon compound may be used.
Examples of the antifouling agent include antifouling agents described in JP-A-2007-264279.
It is also preferable to use a commercially available antifouling agent. Examples of such commercially available antifouling agents (non-reactive) include Megafac series manufactured by DIC Corporation, such as trade names MCF350-5, F445, F455, F178, F470, F475, F479, F477, and TF1025. , F478 and F178K, TSF series manufactured by Toshiba Silicone Co., Ltd., X22 series and KF series manufactured by Shin-Etsu Chemical Co., Ltd., and Silaplane series manufactured by Chisso Corporation.
As a commercially available antifouling agent (reactivity), trade name SUA1900L10 and trade name SUA1900L6 manufactured by Shin-Nakamura Chemical Co., Ltd., trade name Ebecryl 350, trade name Ebecryl 1360 and trade name KRM7039 manufactured by Daicel UC Corporation, UT3971 manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Def Co., Ltd., trade name Defensa TF3001, Def Co., Ltd. TF3000 and trade name Defensa TF3028, Kyoeisha Chemical Co., Ltd. trade name Light Procoat AFC3000, Shin-Etsu Chemical Trade name KNS5300 manufactured by GE Toshiba Silicone Co., Ltd., trade names UVHC1105 and UVHC8550 manufactured by GE Toshiba Silicone, and trade name ACS-1122 manufactured by Nippon Paint Co., Ltd.

(Lubricant)
The easy slip agent has a function of forming minute irregularities on the surface of the HC layer and imparting blocking resistance to the optical film. In addition, blocking refers to a phenomenon in which one surface and the other surface of an optical film stick together when the optical film is laminated or when the optical film is wound into a roll. When blocking occurs, the optical film cannot be smoothly fed out from the roll, and in the subsequent process, wrinkles are generated in the optical film or the optical film meanders. In addition, unevenness is generated in the blocked portion, which is a factor that impairs optical uniformity such as transparency.
In the method for producing an optical film according to the present invention, the second curable resin composition for a hard coat layer further contains an easy lubricant having an average primary particle size of 50 to 300 nm. Is preferable.

As the lubricant, conventionally known lubricants such as inorganic fine particles or organic fine particles can be used.
The average primary particle size of the lubricant is preferably 50 to 300 nm. When the average primary particle size is 50 nm or more, minute irregularities are easily formed on the surface of the HC layer, and it is easy to impart blocking resistance to the optical film. When the average primary particle size is 300 nm or less, the transparency of the optical film is not impaired, and an increase in haze can be suppressed.
When using a lubricant, the content of the lubricant is 0.1 to 3.0% by mass with respect to the total solid content of the second composition. To preferred.
Specific examples of the lubricant include silica fine particles (trade name MIBKSIR manufactured by Catalyst Kasei Kogyo Co., Ltd.).

(High refractive index fine particles)
High refractive index fine particles may be used to increase or adjust the refractive index of the HC layer.
As will be described later, when the low refractive index layer is provided on the HC layer directly or via the high refractive index layer, the second composition contains high refractive index fine particles so that the HC layer has In the film thickness direction, the closer to the interface of the HC layer opposite to the light-transmitting resin substrate, the more the high refractive index fine particles are present (the closer the interface to the light-transmitting resin substrate side, Can be less). Thereby, the refractive index on the upper side of the HC layer can be selectively increased or adjusted, and the difference in refractive index with these layers can be adjusted. Therefore, the antireflection performance of the optical film can be enhanced.
The high refractive index fine particles of the present invention are fine particles having a refractive index of 1.50 to 2.80.
Examples of such high refractive index fine particles include high refractive index fine particles such as titanium oxide, zirconium oxide, antimony tin oxide, and antimony oxide described in Patent Document 1 and Japanese Patent Application Laid-Open No. 2007-272132. Refractive index fine particles and the like can be used.
The average primary particle size of the high refractive index fine particles is preferably 1 to 100 nm from the viewpoint of ensuring the transparency of the HC layer.
The high refractive index fine particles may be used alone or in combination of two or more.

((Iii) step)
In the step (iii), the first composition and the second composition are adjacently applied to one side of the light transmissive substrate from the light transmissive substrate side to form a coating film. .
The method of simultaneous application is not particularly limited, and a conventionally known simultaneous application method such as die coating or slide coating can be used. In the present invention, die coating is preferred.

FIG. 1 is a schematic view showing an example of the simultaneous application in step (iii) in the method for producing an optical film according to the present invention.
The first composition 40 and the second composition 50 are discharged from the slits 31 and 32 of the die coater head 20 of the two-slot extrusion type die coater, respectively, on one side of the light transmissive resin base material 10. Let it be a coating film. Of the two slits 31 and 32 of the extrusion type die coater, the lower side of the HC layer is formed by curing from the slit 31 located on the upstream side with respect to the traveling direction of the light transmissive resin base material 10. The first composition 40 is applied by discharging a second composition 50 that cures and forms the upper side of the HC layer from the slit 32 positioned on the downstream side.

In FIG. 1, a state in which the first composition 40 and the second composition 50 are simultaneously applied is shown. In addition to these two compositions 40 and 50, a composition for a high refractive index layer and a low composition described later are used. You may apply | coat the composition for refractive index layers simultaneously.
There is an advantage that the production process can be simplified by simultaneously applying a composition for forming other layers such as a high refractive index layer and a low refractive index layer together with the two compositions 40 and 50.
When another layer is provided at a position on the HC layer by simultaneous application, a slot for discharging a composition for forming the other layer on the downstream side with respect to the traveling direction of the light-transmitting resin substrate is further provided. It may be provided and applied simultaneously.
For example, using a three-slot die coater (not shown), the first composition 40 is formed on the light-transmitting resin substrate, the second composition 50 is formed thereon, and the composition for the low refractive index layer is formed thereon. It is also possible to obtain an optical film having a layer structure of light-transmitting resin base material / HC layer / low refractive index layer by simultaneous application and curing by light irradiation or heating.

  In the method for producing an optical film according to the present invention, the first composition when the coater gap 60 that is the distance between the die coater head 20 and the light transmissive resin substrate 10 and the light transmissive resin substrate 10 are simultaneously applied. It is preferable that the total thickness 70 of the coating film of the object 40 and the second composition 50 is in a relationship of twice the coater gap 60 <thickness 70. By simultaneously coating while maintaining such a relationship, the coating bead formed between the light-transmitting resin substrate 10 and the die coater head 20 is stabilized. In particular, this coating bead tends to become unstable as the layer formed by coating becomes thinner, causing unevenness and streaks on the coated surface and deteriorating the appearance. However, the coating bead 60 has a thickness of 70 and a thickness of 70. By maintaining the relationship, the coated bead can be stabilized. In addition, a coating bead means the liquid pool produced | generated between a coating device and a base material.

((Iv) step)
In the step (iv), the hard coat layer is formed by curing the coating film obtained in the step (iii) by light irradiation and / or heating.
For light irradiation, ultraviolet rays, visible light, electron beams, ionizing radiation, or the like is mainly used. In the case of ultraviolet curing, ultraviolet rays or the like emitted from light such as an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, or a metal halide lamp are used. The light irradiation amount may be 50 to 300 mJ / cm ² as an integrated exposure amount at an ultraviolet wavelength of 365 nm.
When heating, it processes at the temperature of 40 to 120 degreeC normally. Moreover, you may react by leaving it to stand for 24 hours or more at room temperature (25 degreeC).

In the step (iv), drying may be appropriately performed as necessary before light irradiation or heating.
Examples of the drying method include reduced-pressure drying or heat drying, and a method combining these drying methods. Moreover, when drying at normal pressure, it is preferable to dry at 30-110 degreeC. For example, when methyl isobutyl ketone is used as the first solvent or the second solvent, it is usually room temperature to 80 ° C., preferably 40 ° C. to 70 ° C., and 20 seconds to 3 minutes, preferably 30 seconds. Drying is performed in about 1 minute.

  The film thickness of the HC layer formed in the step (iv) may be appropriately adjusted according to required hardness, saponification resistance, and the like. The film thickness of the HC layer can be set to 1 to 20 μm, for example.

  In the method for producing an optical film according to the present invention, after the step (iv), (v) the surface of the hard coat layer opposite to the light-transmitting resin substrate is directly or via a high refractive index layer. Including a step of forming a low refractive index layer is preferable because the optical film can be provided with antireflection performance.

FIG. 2 is a schematic view showing an example of the layer structure of the optical film according to the present invention.
In the optical film 1 of FIG. 2, the hard coat layer 80 and the low refractive index layer 90 are provided on one side of the light transmissive resin base material 10 from the light transmissive resin base material 10 side.
At this time, the magnitude relationship of the refractive index of each layer is hard coat layer 80> low refractive index layer 90.
FIG. 3 is a schematic view showing another example of the layer structure of the optical film according to the present invention.
In the optical film 1 of FIG. 3, the hard coat layer 80, the high refractive index layer 100, and the low refractive index layer 90 are provided on one surface side of the light transmissive resin base material 10 from the light transmissive resin base material 10 side. .
At this time, the magnitude relationship of the refractive index of each layer is high refractive index layer 100> hard coat layer 80> low refractive index layer 90.
As shown in FIG. 2 and FIG. 3, the low refractive index layer 90 having the lowest refractive index is usually positioned at the outermost surface on the one surface side of the optical film. When the hard coat layer 80 or the high refractive index layer 100 having a higher refractive index than the low refractive index layer 90 is located on the side, antireflection performance can be imparted to the optical film. Usually, as described above, the low refractive index layer 90 is the outermost surface on the one surface side of the optical film, although not shown, on the surface of the low refractive index layer 90 opposite to the light-transmitting resin substrate 10, Furthermore, an extremely thin antifouling layer or HC layer may be provided as long as the antireflection performance is not impaired. Further, without providing the low refractive index layer 90 or the high refractive index layer 100, a layer such as an antifouling layer may be provided on the surface of the hard coat layer 80 opposite to the light transmissive resin base material 10. .
Hereinafter, the low refractive index layer, the high refractive index layer, and the composition for forming these layers will be described.

(Low refractive index layer)
The low refractive index layer is a layer that exhibits antireflection performance due to a difference in refractive index with a layer adjacent to the light transmissive resin substrate side of the low refractive index layer, and is a layer provided as necessary.
The refractive index of the low refractive index layer can be the refractive index of a conventionally known antireflection film or optical film as long as the magnitude relationship with the HC layer 80 and the high refractive index layer 100 described above is satisfied. The refractive index of the low refractive index layer is usually 1.30 to 1.50, preferably 1.30 to 1.45.
Furthermore, the low refractive index layer preferably satisfies the following formula (1) from the viewpoint of reducing the reflectance.
(M / 4) λ × 0.7 <n ₁ d ₁ <(m / 4) λ × 1.3 Formula (1)
In Formula (1), m is a positive odd number, n ₁ is the refractive index of the low refractive index layer, and d ₁ is the thickness (nm) of the low refractive index layer. Also, λ is the wavelength of light and is a value in the range of 380 to 780 nm.
In addition, satisfy | filling said Formula (1) means that m (a positive odd number. Usually it is 1) which satisfy | fills Formula (1) in the said wavelength range exists.

(Composition for low refractive index layer)
The low refractive index layer composition is cured by light irradiation or the like to form the low refractive index layer.
The 1st binder component quoted by said 1st composition can be used for the composition for low refractive index layers.
In addition, in order to reduce the refractive index of the refractive index layer, conventionally known materials can be used. For example, hollow silica fine particles (fine particles having voids), low refractive index fine particles such as magnesium fluoride and sodium fluoride, fluorine resin, and silicone-containing vinylidene fluoride described in JP-A-2007-272132 A copolymer or the like can be used.
When using low refractive index fine particles, the average primary particle diameter of the low refractive index fine particles is preferably 30 to 80% of the thickness of the low refractive index layer so as not to impair the appearance and reflectance of the optical film. .
The material for lowering the refractive index may be used alone or in combination of two or more.

(High refractive index layer)
The high refractive index layer is a layer provided as necessary in order to improve the antireflection performance when the low refractive index layer is provided. The high refractive index layer is provided adjacent to the light transmissive resin substrate side of the low refractive index layer, and has a function of increasing the refractive index difference from the low refractive index layer.
The refractive index of the high refractive index layer can be the refractive index of a conventionally known antireflection film or optical film as long as the magnitude relationship with the HC layer 80 and the low refractive index layer 90 described above is satisfied. The refractive index of the high refractive index layer is usually 1.50 to 2.80.
What is necessary is just to set the thickness of a high refractive index layer suitably, for example, it is preferable that it is 10-300 nm.

(Composition for high refractive index layer)
The high refractive index layer composition is cured by light irradiation or the like to form the high refractive index layer.
The 1st binder component quoted by said 1st composition can be used for the composition for high refractive index layers.
In order to increase or adjust the refractive index of the high refractive index layer, the high refractive index fine particles described in the second composition can be used.
When high refractive index fine particles are used, the average primary particle size of the high refractive index fine particles is preferably 1 to 100 nm from the viewpoint of the transparency of the optical film.
High refractive index fine particles may be used alone or in combination of two or more.

The method for providing the low refractive index layer and the high refractive index layer is not particularly limited, and a low refractive index layer composition or a high refractive index layer composition is applied by a conventionally known coating method, and the coating film is applied to the HC. As with the layer, it may be formed by curing by light irradiation or heating.
As a coating method, for example, a slide coating method, a bar coating method, a roll coater method and the like described in Patent Document 1 can be used.
The low refractive index layer and the high refractive index layer are separated from the HC layer, that is, separately from the simultaneous application of the first composition and the second composition, the composition for the low refractive index layer and the high refractive index layer. It may be formed by applying a composition for use. The low refractive index layer and the high refractive index layer may be formed by simultaneously applying the low refractive index layer composition and the high refractive index layer composition together with the first composition and the second composition. good.

  In the method for producing an optical film according to the present invention, before the step (iii), further includes (vi) a step of forming an antistatic layer on the surface on which the hard coat layer of the light-transmitting resin substrate is provided. Is preferable because it can impart antistatic performance to the optical film.

FIG. 4 is a schematic view showing another example of the layer structure of the optical film according to the present invention.
In the optical film 1 of FIG. 4, an antistatic layer 110, a hard coat layer 80, and a low refractive index layer 90 are provided on one side of the light transmissive resin base material 10 from the light transmissive resin base material 10 side.
Hereinafter, the antistatic layer and the composition for forming the antistatic layer will be described.

(Antistatic layer)
The antistatic layer is a layer having a function of imparting antistatic performance to the optical film, and is a layer provided as necessary.
The thickness of the antistatic layer may be the thickness of a conventionally known antistatic layer, and may be, for example, 30 nm to 1 μm.

(Composition for antistatic layer)
The antistatic layer composition contains an antistatic agent and a binder component, and is cured by light irradiation or heating to form the antistatic layer.
The first binder component mentioned in the first composition can be used in the antistatic layer composition.
As the antistatic agent, those mentioned in the first composition can be used.
An antistatic agent may be used individually by 1 type, and may be used in combination of 2 or more type.
The content of the antistatic agent is not particularly limited and may be appropriately adjusted and used. For example, the surface resistivity of the antistatic layer is preferably 1.0 × 10 ¹³ Ω / □ or less, and more preferably 1.0 × 10 ⁸ Ω / □ or less. What is necessary is just to use so that a resistivity may become this range.

  The method of providing the antistatic layer is not particularly limited as long as it is provided at a position on the light transmitting substrate side of the HC layer, and the composition for the antistatic layer is the same as the low refractive index layer and the high refractive index layer. What is necessary is just to apply | coat an object and harden | cure a coating film by light irradiation or a heating.

(Optical film)
The optical film which concerns on this invention is an optical film characterized by being obtained by the said manufacturing method.
The optical film obtained by the above-described production method has an appropriate viscosity of the first composition and the second composition, and the two compositions are not mixed together. Is good.
In the manufacturing method described above, the reactive silica fine particles are included only in the first composition that cures to form the lower side of the HC layer, and the second composition that cures to form the upper side of the HC layer includes The reactive silica fine particles are not included. And since the entire two compositions are not mixed even by simultaneous application, even if the optical film is saponified, there are few silica fine particles on the upper side of the HC layer, so that the outflow and dropping of the silica fine particles are suppressed. The Further, the portion where the amount of the silica fine particles on the lower side is large also functions as a base. Therefore, the optical film is excellent in saponification resistance and hardness.
Furthermore, since the reactive silica fine particles are contained in the first composition that is lower than the second composition at the time of simultaneous application, the coating film of the first composition and the second composition is cured. In the HC layer, a large amount is present on the lower side, and the abundance decreases as the surface is closer to the surface of the HC layer (the surface opposite to the light-transmitting substrate). Since the first composition and the second composition are appropriately mixed at the portion where the two compositions are in contact with each other, the reactive silica fine particles also move in a small amount to the upper side. When silica fine particles are contained only on the lower layer side by the sequential coating method or the half cure method, an interface between the lower layer side containing the silica fine particles and the upper layer side not containing the silica fine particles is clearly generated. In contrast, in the optical film obtained by the above production method, the closer to the surface of the HC layer, the smaller the amount of silica fine particles present, but the two compositions are appropriately mixed before curing. Since the silica fine particles migrate to the upper side of the HC layer, no interface is formed in the HC layer, the generation of interference fringes is suppressed, and the appearance is good.

  The optical film according to the present invention is an optical film in which at least a hard coat layer is provided on one side of the light-transmitting resin substrate, and the hard coat layer has an average primary particle size of 1 to 100 nm. In the hard coat layer, in the film thickness direction of the hard coat layer, the abundance of the silica fine particles is smaller as it is closer to the interface on the side opposite to the light-transmitting resin substrate. And

FIG. 5 is a cross-sectional view schematically showing an example of a state of distribution of silica fine particles in the hard coat layer of the optical film according to the present invention.
The hard coat layer 80 of the optical film 1 includes silica fine particles 120, and the amount of the silica fine particles 120 in the hard coat layer in the film thickness direction is the interface on the side opposite to the light transmissive resin substrate 10. The closer it is to the less.
Thus, if the silica fine particle is so small that it is closer to the interface of the HC layer opposite to the light-transmitting resin base material, dropping and outflow of the silica fine particle from the interface are suppressed even when the optical film is saponified. The Therefore, the saponification resistance of the optical film can be further improved.
In the optical film obtained by the method for producing an optical film according to the present invention, the reactive silica fine particles contained in the first composition are usually subjected to a reaction on the reactive group on the particle surface during the formation of the HC layer. Since it is later, it becomes silica fine particles.
In FIG. 5, the silica fine particles 120 are illustrated in an enlarged and exaggerated manner.

In the optical film according to the present invention, in the hard coat layer, 90% or more of the total amount of the silica fine particles is present in a region from the light-transmitting resin base material to 80% of the film thickness of the hard coat layer. Is also possible.
As shown in FIG. 5, in the hard coat layer 80, 90% or more of the total amount of the silica fine particles 120 exists in a region from the light-transmitting resin substrate 10 to 80% of the film thickness of the hard coat layer 80. As a result, the saponification resistance is further enhanced.

In the optical film according to the present invention, the hard coat layer contains a lubricant having an average primary particle size of 50 to 300 nm, and the hard coat layer has an interface opposite to the light-transmitting resin substrate. It is also possible to form irregularities having an arithmetic average roughness Ra in accordance with JIS B0601 (1994) of 3 to 50 nm and an average interval Sm between convex portions of 100 nm to 7 μm.
In the above production method, when the second composition contains a lubricant having an average primary particle size of 50 to 300 nm, the surface of the HC layer that is a cured film (on the side opposite to the light-transmitting resin substrate of the HC layer) On the interface, irregularities having Ra of 3 to 50 nm and Sm of 100 nm to 7 μm are formed. The minute unevenness imparts blocking resistance to the optical film.
In addition, said Ra and Sm were calculated | required on condition of the following using the surface roughness measuring machine by the Kosaka laboratory, brand name SE-3400.
Surface roughness detector stylus (trade name SE2555N (2μ standard) manufactured by Kosaka Laboratory Ltd.)
・ Tip radius of curvature 2μm, apex angle 90 degrees, material diamond Measurement conditions of surface roughness measuring instrument ・ Reference length (cutoff value λc of roughness curve): 0.8 mm,
Evaluation length (reference length (cutoff value λc) × 5): 4.0 mm
・ Feeding speed of stylus: 0.1 mm / s

In the optical film according to the present invention, a low refractive index layer or a high refractive index layer and a low refractive index layer are further provided on the surface of the hard coat layer opposite to the light-transmitting resin base material from the hard coat layer side. It may be done.
The antireflection performance of the optical film can be enhanced by using the layer structure as shown in FIG. 2 or FIG.
Since the low refractive index layer and the high refractive index layer have been described in the above manufacturing method, description thereof is omitted here.

In the optical film according to the present invention, an antistatic layer may be further provided between the light-transmitting resin substrate and the hard coat layer.
By adopting the layer structure as shown in FIG. 4, the antistatic property of the optical film can be enhanced.
Since the antistatic layer has been described in the above manufacturing method, description thereof is omitted here.

  In the optical film according to the present invention, the hardness of the pencil hardness test (4.9 N load) specified in JIS K5600-5-4 (1999) can be 3H or more. This is presumably because the HC layer contains a large amount of silica fine particles on the lower side (base) and the lower side has high hardness.

(Polarizer)
The polarizing plate according to the present invention is characterized in that the optical film is disposed on one surface side of the polarizing element, and the light transmissive resin substrate side of the optical film is directed toward the polarizing element.
FIG. 6 is a schematic diagram showing an example of the configuration of the polarizing plate according to the present invention.
The polarizing plate 2 is formed by laminating (laminating) one side of the polarizing element 130 with the light transmissive resin substrate 10 side of the optical film 1 facing the polarizing element 130.

The polarizing element is not particularly limited, and for example, a polyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetal film, an ethylene-vinyl acetate copolymer saponified film which is dyed and stretched with iodine or the like can be used.
In the laminating process of the polarizing element and the optical film, it is preferable to saponify the light-transmitting resin base material (optical film) with an alkaline solution. By the saponification treatment, the adhesiveness is improved and an antistatic effect can be obtained. Thus, it is preferable that the transparent resin base material in the case of a saponification process is TAC.

(Image display device)
An image display device according to the present invention includes the optical film.
As the image display device, a conventionally known image display device can be used. For example, LCD, PDP, EL display device, projection display, CRT display device and the like.
The image display device according to the present invention may be provided with the above optical film, and may be provided with the light transmissive substrate side of the optical film facing the image display surface. A liquid crystal panel may be provided with a polarizing plate provided with a film.

  Hereinafter, the present invention will be described more specifically with reference to examples. These descriptions do not limit the present invention.

As reactive silica fine particles (1), a colloidal silica MIBK dispersion manufactured by Nissan Chemical Industries, Ltd., trade name MIBK-SDL (average primary particle size 44 nm, solid content 40%, surface treatment agent; 3-methacryloxy Propyltrimethoxysilane) was used.
As reactive silica fine particles (2), colloidal silica MIBK dispersion manufactured by Nissan Chemical Industries, Ltd., trade name MIBK-SDZL (average primary particle size 80 nm, solid content 40%, surface treatment agent; 3-methacryloxy Propyltrimethoxysilane) was used.
As reactive silica fine particles (3), a colloidal silica MIBK dispersion manufactured by JGC Catalysts & Chemicals Co., Ltd., trade name DP1039SIV (average primary particle size 20 nm, average number of connections 3.5, average secondary particle size 55 nm, An average primary particle size of 44 nm, a solid content of 40%, a surface treatment agent; 3-methacryloxypropyltrimethoxysilane) was used.
As the low refractive index fine particles, hollow silica fine particles (average primary particle size 50 nm, solid content 20%, porosity 40%) were used.
As a binder component (1), Shin-Nakamura Chemical Co., Ltd. polyfunctional urethane acrylate, brand name U-4HA (molecular weight 600, functional group number 4) was used.
As the binder component (2), trade name KAYARAD-DPHA (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate) manufactured by Nippon Kayaku Co., Ltd. was used.
As the binder component (3), trade name KAYARAD-PET30 (pentaerythritol triacrylate) manufactured by Nippon Kayaku Co., Ltd. was used.
As the binder component (4), trade name BS371 (polymer acrylate having a weight average molecular weight of 40000 and a reactive functional group of 30 or more) manufactured by Arakawa Chemical Industries, Ltd. was used.
As the binder component (5), trade name LINC-3A (fluorine monomer) manufactured by Kyoeisha Chemical Industry Co., Ltd. was used.
As the solvent (1), methyl ethyl ketone having permeability to the TAC substrate was used.
Methyl isobutyl ketone was used as the solvent (2).
As a thickener, trade name Selney HPC-M (hydroxypropylcellulose) manufactured by Nippon Soda Co., Ltd. was used.
As the antifouling agent, trade name 5101X (both terminal tetrafunctional methacrylate-modified perfluoropolyether compound) manufactured by Solvay Solexis Co., Ltd. was used.
As a lubricant, trade name SIRMEK-E03 (average primary particle size 147 nm, silica particles, MEK dispersion, solid content 15%) manufactured by CIK Nanotech Co., Ltd. was used.
As a photopolymerization initiator (1), trade name Irgacure 184 manufactured by Ciba Specialty Chemicals Co., Ltd. was used.
As a photopolymerization initiator (2), trade name Irgacure 127 manufactured by Ciba Specialty Chemicals Co., Ltd. was used.
A TAC substrate (thickness 40 μm, triacetyl cellulose resin film, trade name: KC4UY) manufactured by Konica Minolta Co., Ltd. was used as the light transmissive substrate.
The following abbreviations represent the following:
MIBK: methyl isobutyl ketone MEK: methyl ethyl ketone DPPA: dipentaerythritol pentaacrylate DPHA: dipentaerythritol hexaacrylate IPA: isopropanol PETA: pentaerythritol triacrylate TAC: triacetyl cellulose

(Preparation of composition)
The composition of each was mix | blended and the composition was prepared.

(First composition 1, viscosity 7.8 mPa · s)
Reactive silica fine particles (1) MIBK-SDL: 43.9 parts by mass Binder component (1) U-4HA: 26.4 parts by mass Solvent (1) MEK: 28.6 parts by mass Photopolymerization initiator (1) Irgacure 184: 1.1 parts by mass

(First composition 2, viscosity 6.5 mPa · s)
Reactive silica fine particles (1) MIBK-SDZL: 43.9 parts by mass Binder component (2) KAYARAD-DPHA: 26.4 parts by mass Solvent (1) MEK: 28.6 parts by mass Photopolymerization initiator (1) Irgacure 184: 1.1 parts by mass

(First composition 3, viscosity 9.5 mPa · s)
Reactive silica fine particles (3) DP1039SIV: 43.9 parts by mass Binder component (2) KAYARAD-DPHA: 13.2 parts by mass Binder component (4) BS371: 13.2 parts by mass Solvent (1) MEK: 28.6 parts by mass Part Photopolymerization initiator (1) Irgacure 184: 1.1 parts by mass

(Second composition 1, viscosity 30.5 mPa · s)
Binder component (2) KAYARAD-DPHA: 28.8 parts by mass Binder component (4) BS371: 28.8 parts by mass Solvent (2) MIBK: 40.0 parts by mass Photopolymerization initiator (1) Irgacure 184: 2. 4 parts by mass

(Second composition 2, viscosity 14.7 mPa · s)
Binder component (1) U-4HA: 57.6 parts by mass Solvent (2) MIBK: 40.0 parts by mass Photopolymerization initiator (1) Irgacure 184: 2.4 parts by mass

(Composition for low refractive index layer)
Hollow silica fine particles: 15.0 parts by mass Binder component (3) PET-30: 1.0 part by mass Binder component (5) LINC-3A: 1.0 part by mass Solvent (2) MIBK: 83.0 parts by mass Photopolymerization Initiator (2) Irgacure 127: 0.1 part by mass

(Example 1)
Using a two-slot die coater on the TAC substrate, the first composition 1 is positioned on the TAC substrate (lower) side than the second composition 1. And the 2nd composition 1 was simultaneously apply | coated adjacently with the application | coating speed | rate of 20 m / min, and the coating film was formed. The coating film was dried in a heating oven at a temperature of 70 degrees for 30 seconds to remove the solvent. Subsequently, the coating film was irradiated with ultraviolet rays at an irradiation amount of 100 mJ / cm ² using an ultraviolet irradiation device to cure the coating film to form a hard coat layer having a dry film thickness of 11 μm, thereby obtaining an optical film.

(Example 2)
In Example 1, except that the first composition 2 was used instead of the first composition 1 and the second composition 2 was used instead of the second composition 1, the optical composition was the same as in Example 1. A film was obtained.

(Example 3)
In Example 1, an optical film was obtained in the same manner as in Example 1 except that the first composition 3 was used instead of the first composition 1.

( Reference Example 4)
In Example 3, the same procedure as in Example 3 was repeated except that 1.0 part by mass of a thickener (Serny HPC-M) was added to the first composition 3 to adjust the viscosity to 28.5 mPa · s. A film was obtained.

(Example 5)
In Example 3, the optical composition was the same as in Example 3 except that 0.2 parts by mass of the antifouling agent (5101X) and 7.1 parts by mass of the lubricant (SIRMEK-E03) were added to the second composition 1. A film was obtained.

(Example 6)
In Example 3, after the hard coat layer was formed, the low refractive index layer composition was applied onto the HC layer using a slot die to form a coating film. Next, the coating film is dried and irradiated with ultraviolet rays in the same manner as the hard coat layer, a low refractive index layer having a dry film thickness of 100 nm is formed, and an optical film having an HC layer and a low refractive index layer on the TAC substrate is obtained. It was.

(Comparative Example 1)
In Example 1, MEK was added to the first composition 1, the viscosity of the first composition 1 was 0.9 mPa · s, and MIBK was added to the second composition 1 to An optical film was obtained in the same manner as in Example 1 except that the viscosity was adjusted to 1.3 mPa · s.

(Comparative Example 2)
In Example 1, 10.0 parts by mass of a thickener (Serny HPC-M) was added to the first composition 1, and the amount of MEK in the first composition 1 was reduced. 5.0 parts by weight of a thickener (Serny HPC-M) is added to the composition 2 adjusted to a viscosity of 110.7 mPa · s and the second composition 1 and the amount of MIBK in the second composition 1 is An optical film was obtained in the same manner as in Example 1, except that the viscosity of the second composition 2 was adjusted to 120.0 mPa · s.

(Comparative Example 3)
In Example 1, an optical film was obtained in the same manner as in Example 1 except that MEK was added to the first composition 1 to adjust the viscosity of the first composition 1 to 0.9 mPa · s. It was.

(Comparative Example 4)
In Example 1, 10.0 parts by mass of a thickener (Serny HPC-M) was added to the first composition 1, and the amount of MEK in the first composition 1 was reduced. An optical film was obtained in the same manner as in Example 1 except that the viscosity was adjusted to 110.7 mPa · s.

(Comparative Example 5)
In Example 1, an optical film was obtained in the same manner as in Example 1 except that MIBK was added to the second composition 1 to adjust the viscosity of the second composition 1 to 1.3 mPa · s. It was.

(Comparative Example 6)
In Example 1, the amount of the solvent (1) MEK of the first composition 1 was reduced to adjust the viscosity of the first composition 1 to 12.8 mPa · s. ) An optical film was obtained in the same manner as in Example 1 except that MIBK was added to adjust the viscosity of the second composition 1 to 4.3 mPa · s.

(Comparative Example 7)
In Example 1, 5.0 parts by mass of a thickener (Serny HPC-M) was added to the second composition 1, and the amount of MIBK in the second composition 1 was reduced to reduce the second composition 2. An optical film was obtained in the same manner as in Example 1 except that the viscosity was adjusted to 120.0 mPa · s.

(Comparative Example 8)
On the TAC substrate, the first composition 1 was applied using a slot die coater, and the coating film was dried in a hot oven at a temperature of 70 degrees for 30 seconds to remove the solvent. Next, the coating film was irradiated and cured with an ultraviolet irradiation device so that the irradiation amount was 50 mJ / cm ² , thereby forming an HC layer having a thickness of 7 μm. Next, the second composition 1 was applied onto the HC layer using a slot die coater, and the coating film was dried in a hot oven at a temperature of 70 degrees for 30 seconds to remove the solvent. Next, the coating film was irradiated with an ultraviolet irradiation device so that the irradiation amount was 100 mJ / cm ² to form an HC layer having a total thickness of 11 μm of the upper and lower layers, thereby obtaining an optical film.

(Comparative Example 9)
On the TAC substrate, the first composition 1 was applied using a slot die coater, and the coating film was dried in a hot oven at a temperature of 70 degrees for 30 seconds to remove the solvent. Subsequently, the coating film was irradiated with an ultraviolet irradiation device so that the irradiation amount was 100 mJ / cm ² to form an HC layer having a film thickness of 11 μm, thereby obtaining an optical film.

  Table 1 shows a summary of the types, viscosities, coating methods, and other compositions used in the first and second compositions of the above Examples and Comparative Examples.

(Evaluation of optical film)
About the optical film of the said Example and the comparative example, as shown below, pencil hardness, adhesiveness, the presence or absence of an interference fringe, the presence or absence of a coating stripe, productivity, and saponification resistance were evaluated. Further, the distribution of silica fine particles was evaluated from a TEM photograph of a cross section of the HC layer. The results are shown in Table 2. In Table 2, the ratio of the film thickness is the ratio of the film thickness from the TAC substrate side of the HC layer in which 90% of the silica fine particles are present to the film thickness of the entire HC layer.

(Evaluation of pencil hardness)
The prepared optical film was conditioned for 2 hours under conditions of a temperature of 25 ° C. and a relative humidity of 60%, and then specified in JIS K5600-5-4 (1999) using a test pencil (hardness 3H) specified in JIS S6006. A pencil hardness test (4.9 N load) was performed and measured according to the following criteria.
○: 3H pass (no flaws or one flaw in 5 lines)
×: 3H reject (2 lines or more in 5 lines)

(Evaluation of adhesion)
Put 100 square grids in total on the HC layer side surface of the optical film, conduct 5 continuous peel tests using industrial 24mm cello tape (registered trademark) manufactured by Nichiban Co., Ltd. The number of squares measured was measured, and the adhesion was evaluated by measuring the degree of adhesion based on the following criteria.
Adhesion rate (%) = (number of cells not peeled / total number of cells 100) × 100
○: Adhesion rate 90% or more ×: Adhesion rate less than 90%

(Evaluation of appearance: presence of interference fringes)
Visual inspection was performed using an interference fringe inspection lamp (Na lamp) manufactured by Funatech Co., Ltd., and evaluation was performed according to the following criteria.
○: Interference fringes were hardly seen ×: Interference fringes were clearly visible

(Appearance evaluation: Presence or absence of coating stripes)
The appearance of the optical film (the presence or absence of coating stripes) was visually evaluated.
○: The coating streaks could not be seen. △: The coating streaks looked blurred. ×: The coating streaks were clearly visible.

(Productivity (coating suitability))
In each of the above Examples and Comparative Examples, the applicability of the first composition and the second composition to the TAC substrate when only the coating speed was changed was evaluated according to the following criteria.
○: Can be applied without producing coating stripes even at a coating speed of 10 m / min or more. Δ: Coating speed capable of being applied without producing coating stripes is 1 m / min or less. That cause coating streaks even at high speeds

(Evaluation of saponification resistance)
The produced optical film was immersed in a saponification solution (2N aqueous sodium hydroxide solution) at a temperature of 55 ° C. for 2 minutes. Then, after sufficiently washing with water, it was dried at 70 ° C. for 5 minutes. Using # 0000 steel wool, rubbing 10 times at a friction load of 9.8 × 10 ⁻² MPa (1000 gf / cm ² ), and then visually checking for the presence or absence of scratches or peeling of the cured film, the following criteria Evaluated.
○: No scratch or cured film peeled ×: There was a scratch or cured film peeling

(Summary of results)
From Table 2, the optical film of Examples 1-3 and 5-6 obtained the favorable evaluation result.
Moreover, in the optical film of Example 5, since the antifouling agent was added to the second composition, fingerprints were hardly attached, and even if fingerprints were attached, they could be easily wiped off. Furthermore, in the optical film of Example 5, since an easy-lubricant was added to the 2nd composition, even if it laminated | stacked the optical film, sticking (blocking) of optical films did not arise. In addition, arithmetic mean roughness Ra based on JISB0601 (1994) of the optical film of Example 5 was 7.5 nm, and the average space | interval Sm between convex parts was 3.8 micrometers.
In Example 6 in which the low refractive index layer was formed on the HC layer, the reflectance was lower than that of the optical film without the low refractive index layer, and good antireflection properties were exhibited.
However, the optical films of Comparative Examples 1 to 7 had lower adhesion than the Examples, and the appearance was also caused by coating stripes. Also, the productivity was inferior.
In Comparative Example 8 using the sequential coating method, there was a layer interface between the upper and lower HC layers, interference fringes were generated, and the appearance was poor. Also, the adhesion was poor. In Comparative Example 8, the silica fine particles were uniformly present in the lower HC layer, and the ratio of the film thickness in which 90% of the silica fine particles were present was 90% of the film thickness on the lower layer side.
In Comparative Example 9 in which the single layer coating was performed, the silica particles were present on the surface of the HC layer, resulting in poor saponification resistance.

DESCRIPTION OF SYMBOLS 1 Optical film 2 Polarizing plate 10 Translucent resin base material 20 Die coater head 31, 32 Slit 40 First curable resin composition for hard coat layers 50 Second curable resin composition for hard coat layers 60 Coater gap 70 Total thickness of coating film of first curable resin composition for hard coat layer and second curable resin composition for hard coat layer 80 Hard coat layer 90 Low refractive index layer 100 High refractive index layer 110 Charging Prevention layer 120 Silica fine particle 130 Polarizing element

Claims (6)

(I) preparing a light transmissive resin base material;
(Ii) Reactivity having an average primary particle size of 1 nm or more and 100 nm or less having a reactive group on the particle surface, which is a reactive group having photocurability or thermosetting property between the same and different reactive groups, respectively. First hard-coat layer curable resin composition containing silica fine particles, first binder component having a reactive group and first solvent, and having a viscosity of 5 mPa · s to 9.5 mPa · s and the reaction Curable resin composition for second hard coat layer, containing no reactive silica fine particles, including a second binder component having a reactive group and a second solvent, and having a viscosity of 10 mPa · s to 30.5 mPa · s Preparing a product,
(Iii) The first curable resin composition for hard coat layer and the second curable resin for hard coat layer are formed on one side of the light transmissive resin substrate from the light transmissive resin substrate side. Applying the composition adjacent to each other to form a coating film;
(Iv) A method for producing an optical film, comprising a step of forming a hard coat layer by curing the coating film obtained in the step (iii) by light irradiation and / or heating.   The light-transmitting resin substrate is a triacetyl cellulose substrate, and in the first curable resin composition for a hard coat layer, the ratio of methyl ethyl ketone to the total mass of the first solvent is 50% by mass or more. The manufacturing method of the optical film of Claim 1. An optical film in which at least a hard coat layer is provided on one side of the light-transmitting resin base material,
The hard coat layer includes silica fine particles having an average primary particle size of 1 nm or more and 100 nm or less. In the hard coat layer, the amount of the silica fine particles in the film thickness direction of the hard coat layer is the light-transmitting resin. The closer to the interface opposite the substrate, the less
In the hard coat layer, the region from the light-transmissive resin substrate up to 70% of the thickness of the hard coat layer, there is less than 90% of the total amount of the silica fine particles, from the light transmissive resin substrate An optical film, wherein 90% or more of the total amount of the silica fine particles is present in a region of up to 75% of the film thickness of the hard coat layer. A low refractive index layer having a lower refractive index than the interface of the hard coat layer on the side opposite to the light transmissive resin substrate, and the interface on the opposite side of the hard coat layer to the light transmissive resin substrate, or the hard coat layer From the coat layer side, a high refractive index layer having a higher refractive index than the interface of the hard coat layer opposite to the light transmissive resin substrate, and an interface of the hard coat layer opposite to the light transmissive resin substrate The optical film according to claim 3 , wherein a low refractive index layer having a lower refractive index is provided. A polarizing plate comprising the optical film according to claim 3 or 4 disposed on one surface side of a polarizing element, the light transmissive resin substrate side of the optical film facing the polarizing element. . An image display device comprising the optical film according to claim 3 .

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