TWI581974B - Method for producing optical film, optical film, polarizer and image display device - Google Patents

Description

Optical film manufacturing method, optical film, polarizing plate and image display device

The present invention relates to an optical film provided in front of a display (image display device) such as a liquid crystal display (LCD), a cathode tube display device (CRT), an organic electroluminescence (organic EL), or a plasma display (PDP). A polarizing plate and an image display device including the optical film.

In the above-described display, it is required to impart scratch resistance to the image display surface of the display in the case of unfair damage during operation. In this case, it is possible to impart scratch resistance to the image display surface of the display by using an optical film and an HC film which are provided with a hard coat (hereinafter referred to as "HC") layer on the base film (for example, Patent Document 1) .

Further, in the above-described display, in order to improve the visibility of the display surface, it is required that the light reflected from an external light source such as a fluorescent lamp is less reflected. As a method of suppressing reflection of external light, it is generally known to provide a low refractive index layer having the lowest refractive index on the outermost surface of the display surface, and an antireflection film having a high refractive index layer having a high refractive index adjacent to the display side of the low refractive index layer. , the method set in front of the display. Further, it is also known to provide an antireflection film having a medium refractive index layer, a high refractive index layer, and a low refractive index layer on the display side.

In order to form a layer having such a high degree of refractive index, a refractive index layer containing high refractive index fine particles is generally disposed adjacent to the low refractive index layer, and a functional layer such as an HC layer and an antistatic layer adjacent to the low refractive index is contained. High refractive index fine particles (for example, Patent Document 2).

However, when the medium refractive index layer or the high refractive index layer and the functional layer such as the HC layer are sequentially formed one by one (sequentially), there is a problem that the number of steps increases and the manufacturing cost increases, and the high refractive index layer and the HC The problem of low adhesion of layers and the like.

Further, in the invention of Patent Document 2, the high refractive index fine particles are biased and formed in the vicinity of the interface on the low refractive index layer side of the hard coat layer, but the boundary between the skin layer in the hard coat layer and other portions is remarkable. There is a problem in the boundary that produces interference fringes.

In the invention of Patent Document 3, an optical film which can reduce reflection and prevent interference fringes is provided, and a hard coat layer, a high refractive index oblique hard coat layer, and a low refractive index layer are sequentially laminated on a substrate. The optical film is proposed to form a high refractive index oblique hard coat layer in which a hard coat layer is integrated with a high refractive index oblique hard coat layer according to a specific method, and to prevent interference of the striped optical film.

However, in the invention of Patent Document 3, it is also difficult to obtain a refractive index-slanted hard coat layer with good efficiency, and a method of obtaining a refractive index-slanted hard coat layer with higher productivity and high productivity is required.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2008-165040

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2009-086360

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2009-265658

The present invention has been made to solve the above problems, and an object of the invention is to provide an optical film having a refractive index oblique hard coat layer which is easier and more productive.

Moreover, the present invention has an object of providing a polarizing plate and an image display device including such an optical film.

As a result of the review, the inventors of the present invention found that two compositions of a composition containing high refractive index fine particles having a specific viscosity and a composition containing no high refractive index fine particles having a specific viscosity were prepared from the substrate side. In the order of the layers, the composition containing no high refractive index fine particles and the composition containing the high refractive index fine particles are sequentially coated, and the diffusion of the high refractive index fine particles can be controlled, which is easy and high in productivity. An optical film having a refractive index oblique hard coat layer is obtained and the present invention has been completed.

That is, the method for producing an optical film of the present invention which solves the above problems includes (i) a step of preparing a light-transmitting substrate, (ii) preparing a first binder component and a first solvent, and not containing high refractive index. a curable resin composition for a first hard coat layer having a particle size of 3 to 100 mPa·s and a high refractive index fine particle having a mean particle diameter of 1 to 100 nm, a second binder component, and a second solvent, and having a viscosity of a step of curing the resin composition for the second hard coat layer of 10 to 100 mPa·s, (iii) one side of the light-transmitting substrate, and the first hard surface of the light-transmitting substrate The curable resin composition for coating layer and the curable resin composition for the second hard coat layer are adjacent to each other, and the curable resin composition for the first hard coat layer is composed of the curable resin for the second hard coat layer. The coating is further coated on the side of the light-transmitting substrate to form a coating film, and (iv) the coating film obtained in the above step (iii) is subjected to light irradiation to be hardened to form a refractive index oblique hard coat layer. A step of.

A curable resin composition for a first hard coat layer (hereinafter referred to simply as "first composition") having a viscosity of 3 to 100 mPa ‧ without containing high refractive index fine particles, and an average particle diameter of 1 to 100 nm a high-refractive-index fine particle, a curable resin composition for a second hard coat layer having a viscosity of 10 to 100 mPa·s (hereinafter, simply referred to as a "second composition", and the first composition is used in a light-transmitting substrate When the side is adjacent and coated at the same time and hardened, the refractive index oblique hard coat layer can be obtained easily and with high productivity.

Here, the refractive index of the refractive index is inclined by the refractive index of the HC layer, which means the refractive index of the opposite side interface of the light-transmitting substrate of the HC layer with respect to the refractive index.

In addition, the inclination of the refractive index means that the refractive index is continuously changed in the gradient of the refractive index in the HC layer from the interface on the opposite side of the light-transmitting substrate toward the light-transmitting substrate-side interface.

The refractive index is inclined in the gradient of the refractive index HC layer, which can be confirmed by the following method. The refractive index tilted HC layer was etched by argon sputtering to expose a portion of the specific depth of the refractive index tilted HC layer, and the high refractive index fine particle content in the exposed portion was measured using an X-ray photoelectron spectroscope (XPS). According to this method, the existence amount distribution of the high refractive index fine particles in the depth direction in which the refractive index is inclined in the HC layer is specified.

Since the refractive index in each depth point of the gradient refractive index HC layer is related to the amount of the high refractive index fine particles, the presence of the high refractive index fine particles in the depth direction of the HC layer by the refractive index is inclined. Confirm that the refractive index is inclined.

Furthermore, the optical film was embedded with a thermosetting resin, and an ultrathin section having a thickness of 80 nm was formed using the optical film embedded by a LEICA micromicrotome, and observed by a transmission electron microscope (TEM). Can be measured.

The term "high refractive index microparticles" means microparticles having a refractive index of 1.50 to 2.80.

In the method for producing an optical film of the present invention, the curable resin composition for the first hard coat layer and/or the curable resin composition for the second hard coat layer further contains a tackifier, and it is easy to control the refractive index tilting hard. The distribution of the high refractive index microparticles in the coating is preferred.

In the method for producing an optical film of the present invention, the absolute value of the difference between the viscosity of the curable resin composition for the first hard coat layer and the viscosity of the curable resin composition for the second hard coat layer is 30 or less. It is preferable to easily control the distribution of the high refractive index fine particles in the gradient refractive hard coat layer.

In the method for producing an optical film of the present invention, the light-transmitting substrate is a triacetyl cellulose substrate, and the first solvent has permeability to the triethylene cellulose substrate, and is suppressed by the optical film. It is preferable from the viewpoint of interference fringes.

In the method for producing an optical film of the present invention, after the step (iv), the method further includes (v) forming a low refractive index layer directly or via a high refractive index layer on the refractive index inclined hard coat layer. A step of. By providing the low refractive index layer directly or in the high refractive index layer on the refractive index inclined HC layer as described above, the antireflection property of the optical film can be further improved.

In the method for producing an optical film of the present invention, the composition for a low refractive index layer which is formed by curing the low refractive index layer contains hollow cerium oxide fine particles, and it is preferable to impart excellent antireflection properties to the optical film.

In the method for producing an optical film of the present invention, the composition for a low refractive index layer which forms the low refractive index layer is cured, and at least one of the low refractive index selected from the group consisting of a metal fluoride and a curable fluororesin is contained. In the case of a material, an optical film having sufficient antireflection properties can also be obtained.

In the method for producing an optical film of the present invention, the composition for a low refractive index layer which forms the low refractive index layer is cured, and does not contain hollow ceria particles, and is selected from the group consisting of metal fluoride and curable fluororesin. At least one type of low refractive index material is preferable in that it is sufficient to prevent both reflectance and alkali resistance from being established.

In the method for producing an optical film of the present invention, it may further comprise (vi) forming a refractive index oblique hard coat surface on the light-transmitting substrate between the steps (i) and (iii). The step of the antistatic layer. The antistatic property of the optical film can be improved via the antistatic layer.

The optical film of the present invention is an optical film obtained by any of the above production methods.

The optical film of the present invention is an optical film having at least one refractive index oblique hard coat layer on one side of the light-transmitting substrate, characterized in that the refractive index oblique hard coat layer has a high refractive index of an average particle diameter of 1 to 100 nm. The fine particles are present in the refractive index oblique hard coat layer, and the amount of the high refractive index fine particles is less toward the side of the light transmissive substrate in the film thickness direction of the gradient refractive index hard coat layer.

In the optical film of the present invention, in the region of the refractive index oblique hard coat layer, the surface of the light-transmitting substrate opposite to the surface side until the refractive index is inclined to 70% of the film thickness of the hard coat layer may exist. 90% or more of the total amount of the high refractive index fine particles. By distributing the high refractive index fine particles in this manner, the refractive index of the surface side interface side of the light-transmitting substrate of the refractive index-slanted HC layer can be efficiently increased.

In the optical film of the present invention, it is also possible to form the above-mentioned refractive index oblique hard coat layer containing a tackifier.

In the optical film of the present invention, the light-transmitting substrate is a triacetyl cellulose substrate, which constitutes a matrix of the above-mentioned refractive index oblique hard coat layer, and also has a refractive index tilt on the triacetyl cellulose substrate. The interface on the hard coat side is preferable from the viewpoint of suppressing interference fringes in the optical film.

In the optical film of the present invention, a high refractive index layer and a low refractive index are further provided on the opposite side of the light transmissive substrate of the refractive index oblique hard coat layer from the low refractive index layer or the refractive index oblique hard coat layer side. The layer is preferable because the antireflection property of the optical film can be further improved.

In the optical film of the present invention, the low refractive index layer contains hollow ceria particles, and it is preferable because it can provide excellent antireflection properties to the optical film.

In the optical film of the present invention, the low refractive index layer has sufficient antireflection properties even when at least one of the low refractive index components selected from the group consisting of metal fluorides and fluororesins is contained.

In the optical film of the present invention, the low refractive index layer does not contain hollow ceria particles, and contains at least one low refractive index component selected from the group consisting of metal fluorides and fluororesins, so that sufficient prevention can be achieved. The two phases of reflectivity and alkali resistance are established.

In the optical film of the present invention, an antistatic layer is further provided between the light-transmitting substrate and the refractive index oblique hard coat layer, and the antistatic property of the optical film can be further improved.

In the optical film of the present invention, the optical film may be immersed in a 2 N aqueous solution of sodium hydroxide maintained at 55 ° C for 2 minutes, and then, after washing with water, dried at 70 ° C for 5 minutes, and then, using # When the steel wool of No. 0000 rubbed the surface of the low refractive index layer back and forth 10 times with a friction load of 0.98 N, the low refractive index layer was imparted with no damage and peeling property.

The polarizing plate of the present invention is characterized in that the optical film is disposed on one surface side of the polarizing element with the light-transmitting substrate side of the optical film facing the polarizing element.

An image display device of the present invention is characterized by comprising the above optical film.

In the method for producing an optical film of the present invention, the first composition having a specific viscosity which does not contain the high refractive index fine particles is adjacent to the two compositions of the second composition containing the specific viscosity of the high refractive index fine particles, and When the first composition is coated on the side of the light-transmissive substrate and coated with a gradient-indexed HC layer, the high-refractive-index particle distribution in the film thickness direction of the gradient-inclined HC layer can be easily controlled. Therefore, according to the method for producing an optical film of the present invention, an optical film having a gradient refractive index HC layer can be obtained easily and with high productivity.

In the polarizing plate and the image display device of the present invention, since the optical film having the refractive index-inclined HC layer is provided, it is difficult to cause damage.

Hereinafter, a method of producing an optical film of the present invention will be described first, and an optical film will be described next.

In the present invention, (meth) acrylate means acrylate and/or methacrylate.

Further, in the light of the present invention, not only electromagnetic waves of wavelengths in the visible light and non-visible light regions, but also electron beam-like particle lines and radiation or ionizing radiation, which are collectively referred to as electromagnetic waves and particle lines.

In the present invention, the average particle diameter of the microparticles means an average value of 20 particles observed by a transmission electron microscope (TEM) photograph of the cross section of the cured film, and may be a primary particle diameter and a secondary particle diameter. Either. That is, it is an average dispersed particle diameter of the whole particle group containing a primary particle diameter and a secondary particle diameter.

In the present invention, the molecular weight, in the case of having a molecular weight distribution, means a weight average molecular weight of a polystyrene-converted value measured by gel permeation chromatography (GPC) using THF as a solvent, and has no molecular weight distribution. , meaning the molecular weight of the compound itself.

In the present invention, the term "hard coating layer" means a pencil hardness test (4.9 N load) prescribed in JIS K5600-5-4 (1999), and shows a hardness of "H" or more.

Further, in the definition of the film and the sheet in the definition of JIS-K6900, the sheet refers to a product which is thin and generally has a thickness which is small and flat in the ratio of length to width, and the film means that the thickness is extremely small as compared with the length and the width. And the maximum thickness is an arbitrarily defined thin and flat product, generally, in the form of a roll type. Therefore, even if the thickness of the sheet is extremely thin, it is called a film, and the boundary between the sheet and the film is not determined, and it is difficult to distinguish clearly. Therefore, in the present invention, the meaning of both the thick and the thin is included, and Defined as "film".

The refractive index was measured by using a spectrophotometer (UV-3100PC manufactured by Shimadzu Corporation) and measuring the average reflectance (R) at a wavelength of 380 to 780 nm. From the obtained average reflectance (R), the value of the refractive index (n) was obtained using the following formula.

R(%)=(1-n ² )/(1+n ² )

The measurement of the dried film thickness was carried out using (IDF-130, manufactured by Mitsutoyo Co., Ltd.).

(Method of manufacturing optical film)

A method for producing an optical film according to the present invention, comprising (i) a step of preparing a light-transmitting substrate, (ii) preparing a first binder component and a first solvent, containing no high-refractive-index particles, and having a viscosity It is a hardening resin composition for a first hard coat layer of 3 to 100 mPa·s and a high refractive index fine particle having a mean particle diameter of 1 to 100 nm, a second binder component, and a second solvent, and has a viscosity of 10 to 100 mPa·s. a step of forming a curable resin composition for the second hard coat layer, (iii) one side of the light transmissive substrate, and a hardenability of the first hard coat layer from the side of the light transmissive substrate The resin composition and the curable resin composition for the second hard coat layer are adjacent to each other, and the curable resin composition for the first hard coat layer is located further than the curable resin composition for the second hard coat layer. The step of simultaneously coating the penetrating substrate side to form a coating film, and (iv) the step of hardening the coating film obtained in the above step (iii) to form a refractive index oblique hard coat layer.

a first composition containing no high refractive index fine particles, having a viscosity of 3 to 100 mPa·s, and a second composition having a high refractive index fine particle having an average particle diameter of 1 to 100 nm and a viscosity of 10 to 100 mPa·s. When the first composition is applied simultaneously to the side of the light-transmitting substrate and hardened, the refractive index-slanted HC layer can be easily and highly productive.

Further, the viscosity of the first composition and the second composition was measured using MCR301 manufactured by Anton Paar Co., Ltd., measuring instrument was PP50, and the measurement temperature was 25 ° C, and the shear rate was 10000 [1/s]. The amount of the substance (ink) was measured and dropped on the stage.

When the viscosity of the first composition and the second composition is less than the above range, it is difficult to control the distribution of the high refractive index fine particles in the film thickness direction of the refractive index inclined HC layer in the gradient refractive index HC layer, and the high refractive index The microparticles are easily distributed uniformly in the gradient refractive index HC layer.

When the high refractive index fine particles are uniformly distributed in the layer, the refractive index difference becomes large at the interface between the light-transmitting substrate adjacent to the refractive index-inclined HC layer and the antistatic layer. Thereafter, interference fringes are generated in the interface and the appearance of the optical film is deteriorated. Further, the content of the high refractive index fine particles increases, and the manufacturing cost also increases.

Further, when the viscosity of the first composition and the second composition is less than the above range, the coating of the refractive index is inclined on the surface of the HC layer, and the appearance is deteriorated.

On the other hand, when the viscosity of the first composition and the second composition is within the above specific range, even if the two compositions are simultaneously coated, the diffusion or sedimentation of the high refractive index fine particles can be appropriately controlled, and the coating can be easily performed. The refractive index tilting HC layer is obtained with high productivity.

The viscosity of the first composition and the second composition is 3 to 100 mPa·s and 10 to 100 mPa·s, respectively, and the viscosity of the first composition is preferably 3 to 50 mPa·s, more preferably 5 to 30 mPa·s. The viscosity of the second composition is preferably 10 to 50 mPa ‧ s, and more preferably 15 to 30 mPa ‧ s. When the viscosity of the first composition and the second composition are respectively adjusted to the above ranges, diffusion or sedimentation of the high refractive index fine particles can be easily controlled, and the refractive index inclined HC layer can be easily formed. Further, the viscosity of the first composition is 5 to 30 mPa·s, and the viscosity of the second composition is 20 to 30 mPa·s, which makes it easier to control the diffusion or sedimentation of the high refractive index microparticles, and is easy to form the refractive index tilt HC. Layer, so it is better.

When the viscosity of the first composition and the second composition is within the above range, the distribution of the high refractive index fine particles may be appropriately adjusted, but the second composition of the upper layer side of the HC layer having the refractive index is inclined. The viscosity is greater than the viscosity of the first composition, and is superior in terms of productivity.

Further, the absolute value of the difference between the viscosity (mPa‧s) of the first composition and the second composition is 30 or less, and the diffusion or sedimentation of the high refractive index fine particles can be more easily controlled, and the gradient refractive index HC layer is easily formed. It is better.

Fig. 1 is a view schematically showing an example of a method for producing an optical film of the present invention.

As shown in Fig. 1(a), the light-transmitting substrate 10 is prepared. Next, on the light-transmitting substrate 10, the first composition and the second composition are applied adjacent to each other while the first composition is positioned on the side of the light-transmitting substrate 10 to form a coating film. The light is irradiated and hardened, and as shown in FIG. 1(b), the refractive index tilting hard coat layer 20 is formed as the amount of the high refractive index fine particles 30 in the layer is closer to the light-transmitting substrate side. The optical film 1 was obtained.

Hereinafter, the light-transmitting substrate, the first composition, and the second composition used in the method for producing an optical film of the present invention will be described.

(light penetrating substrate)

The light-transmitting substrate of the present invention is not particularly limited as long as it satisfies the physical properties of the light-transmitting substrate as the optical film, and the conventionally used hard-coated film and optical film can be appropriately selected and used. Cellulose (TAC), polyethylene terephthalate (PET), or cyclic olefin polymer (COP), and the like.

The light transmittance of the light-transmitting substrate in the visible light region of 380 to 780 nm is preferably 50% or more, more preferably 70% or more, and particularly preferably 85% or more. In addition, the measurement of the light transmittance can be performed by using an ultraviolet-visible spectrophotometer (for example, UV-3100PC manufactured by Shimadzu Corporation) and using it at room temperature or in the atmosphere.

Further, the light-transmitting substrate may be subjected to an alkalizing treatment and a surface treatment such as providing a primer layer or the like. Further, an additive such as an antistatic agent may be contained in the light transmissive substrate.

The thickness of the light-transmitting substrate is not particularly limited, but is usually about 20 to 300 μm, preferably 40 to 200 μm.

In the case where the HC layer having the high refractive index fine particles is formed once by using one composition (hereinafter referred to as "single layer one-time coating method", the light-transmitting substrate is a TAC substrate, Even if the solvent and the binder component contained in the composition are impregnated into the TAC substrate, the high refractive index fine particles are uniformly distributed in the HC layer, and are easily present at the interface on the TAC substrate side of the HC layer and in the vicinity thereof. At this interface, interference fringes occur through the difference in refractive index between the TAC substrate (refractive index: 1.49) and the high refractive index fine particles (refractive index: 1.50 to 2.80), and the appearance is deteriorated.

In contrast, according to the method for producing an optical film of the present invention, in the gradient-inclined HC layer, the closer the refractive index of the HC layer is, the closer the amount of the high-refractive-index particles (the particle density per unit volume) is. The light-permeable substrate side is less, and high-refractive-index fine particles are not present or absent at the interface between the refractive index-slanted HC layer and the light-transmitting substrate and in the vicinity thereof. Therefore, even when the TAC substrate is used, the first solvent and the first binder component are easily impregnated into the TAC substrate, and interference fringes do not occur at the interface between the refractive index tilting HC layer and the TAC substrate, and an optical appearance of good appearance can be obtained. film.

(curable resin composition for the first hard coat layer)

The first composition used in the method for producing an optical film of the present invention contains the first binder component and the first solvent, and does not contain high refractive index fine particles, and has a viscosity of 3 to 100 mPa·s. The first composition is adjacent to and coated at the same time as the second composition described later on the side of the light-transmitting substrate.

The first composition not containing the high refractive index fine particles is coated on the light transmissive substrate side at the same time as the second composition containing the high refractive index fine particles, and the refractive index inclined HC layer formed by the two kinds of compositions In the film thickness direction of the gradient refractive index HC layer, the amount of the high refractive index microparticles is closer to the light transmissive substrate side. Further, when the first composition and the second composition are simultaneously coated, the first composition and the second composition are formed in an integral form than when the two compositions are applied and cured separately. The film, and the high refractive index fine particles contained in the second composition are moderately distributed in the integrated film as the closer to the side of the light penetrating substrate. Thereby, the first composition suppresses interference by the refractive index difference between the high refractive index fine particles and the lower layer such as the light transmissive substrate or the antistatic layer in the light transmissive substrate side interface of the refractive index tilting HC layer. Stripes have the effect of preventing the appearance of the optical film from deteriorating.

Hereinafter, the first binder component and the first solvent contained in the first composition and, if necessary, other photopolymerization initiators, tackifiers, fine particles, antistatic agents, and leveling agents may be described.

(first binder component)

The first binder component is hardened to form a matrix component of the refractive index tilted HC layer.

Examples of the first binder component include (i) a reactive binder component which is cured by induction light (hereinafter referred to as "photocurable binder component"), and (ii) reactivity which is hardened by induction heat. The binder component (hereinafter referred to as "thermosetting binder component") and (iii) a non-reactive binder component which is cured by drying or cooling without sensing light or heat.

Further, the photocurable binder component and the thermosetting binder component may also be light and heat-curable light and thermosetting binder component.

In the photocurable adhesive component, a binder component which is cured by ionizing radiation (hereinafter referred to as "ionizing radiation curable adhesive component") can be prepared, and a coating composition having excellent coating properties can be prepared. A uniform large-area coating film is formed. Further, the binder component which is cured by ionizing radiation in the coating film is cured by photopolymerization after application, and a cured film having high strength can be obtained.

As the ionizing radiation-curable binder component, a monomer, oligomer or polymer having a polymerizable functional group which is previously known to cause polymerization or the like via ionizing radiation can be used.

The polymerizable functional group is preferably an ethylenically unsaturated bond such as an acrylonitrile group, a vinyl group or an allyl group. The polymerizable functional group may further be an epoxy group.

The ionizing radiation-curable adhesive component is preferably a binder component having two or more polymerizable functional groups in one molecule from the viewpoint of increasing the crosslinking between the binder components at the time of curing.

Examples of the ionizing radiation-curable adhesive component include monofunctional (meth) acrylate, di(meth) acrylate, and tri(meth) acrylate described in JP-A-2004-300210. a polyfunctional (meth) acrylate, a derivative such as the EO (ethylene oxide) modified product, an oligomer which polymerizes the radical polymerizable monomer, a polymer having an ethylenically unsaturated bond, or the like . Further, a photocationic polymerizable monomer and an oligomer such as a compound containing an epoxy group can also be used.

The thermosetting adhesive component may, for example, be a compound having an epoxy group, or a binder epoxy compound described in JP-A-2006-106503.

Examples of the non-reactive adhesive component include polyacrylic acid, polyimide, and polyvinyl alcohol described in JP-A-2004-300210.

The binder components of the above (i) to (iii) may be used alone or in combination of two or more.

(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 is not particularly limited and may be appropriately selected and used depending on the light-transmitting substrate to be used.

Examples of the first solvent include alcohols, ketones, esters, halogenated hydrocarbons, aromatic hydrocarbons, and ethers described in JP-A-2005-316428.

As the first solvent, in addition, for example, tetrahydrofuran, 1,4-two can be used. Alkane, two Ethers such as alkane and diisopropyl ether.

In order to prevent the occurrence of interference fringes, it is preferred to use a solvent (permeability solvent) having permeability to the light-transmitting substrate. The penetrating solvent can also be used in combination with a non-permeating solvent.

Further, the so-called permeability in the present invention includes the concept of swelling or wetting the light-transmitting substrate in addition to the property of impregnating the light-transmitting substrate (i.e., the permeability in a narrow sense).

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, methyl acetate and ethyl acetate. And esters such as butyl acetate, halogenated hydrocarbons, aromatic hydrocarbons such as toluene and xylene, and phenols.

The solvent used for the case where the light-transmitting substrate is triacetyl cellulose (TAC) and the solvent used for the case where the light-transmitting substrate is polyethylene terephthalate (PET) can be enumerated. The solvent described in Japanese Laid-Open Patent Publication No. 2005-316428.

In particular, the light-transmitting substrate is a solvent used in the case of triacetyl cellulose (TAC), and preferably methyl acetate, ethyl acetate, butyl acetate or methyl ethyl ketone.

The solvent used in the case where the light-transmitting substrate is polyethylene terephthalate (PET) is preferably phenol, chlorobenzene, nitrobenzene, chlorophenol or hexafluoroisopropanol.

Further, in addition to the impregnation property, the solvent of the ketone has an effect that the first composition can be easily and uniformly applied to the surface of the light-transmitting substrate, and the evaporation rate of the solvent after application is moderate, and it is difficult to cause unevenness in drying. Therefore, a large-area coating film having a uniform thickness can be easily obtained.

The first solvent may be used alone or in combination of two or more.

When the impregnating solvent and the non-permeating solvent are used in combination as the first solvent, the ratio of the penetrating solvent is preferably 50% by mass or more, and more preferably 80% by mass or more, based on the total mass of the first solvent.

(other components of the first composition)

In the first composition, in order to promote the hardening of the first binder component, adjust the viscosity, hardness, or impart antistatic property, the first composition may contain a photopolymerization initiator, and may be added. Other ingredients such as adhesives, microparticles, antistatic agents and leveling agents.

(photopolymerization initiator)

As the photopolymerization initiator, for example, a photoinitiator such as acetophenone or benzophenone described in JP-A-2007-272132 can be used.

Among them, 1-hydroxy-cycloethyl-phenyl ketone and 2-methyl-1[4-(methylthio)phenyl]-2- The morphyl propan-1-one, which can start and promote photopolymerization even in a small amount, is preferably used in the present invention.

In the case of using a photo-cationic polymerizable binder component, for example, a cationic polymerization initiator described in JP-A-2010-107823 can be used.

The photopolymerization initiator may be used alone or in combination of two or more.

A commercially available product can also be used as the above photopolymerization initiator. For example, 1-hydroxy-cyclohexyl-phenyl ketone is available from Ciba Specialty Chemicals under the trade name IRGACURE 184.

The photopolymerization initiator may be used alone or in combination of two or more.

When a photopolymerization initiator is used, the content thereof is preferably 0.1 to 20% by mass based on the total solid content of the first composition.

(tackifier)

For the purpose of adjusting the viscosity in the first composition, a tackifier of an organic compound and/or an inorganic compound may be contained. By containing the tackifier, the mixing of the first composition and the second composition can be appropriately controlled, and the distribution of the high refractive index fine particles contained in the second composition can be easily controlled.

Examples of the tackifier of the organic compound include ethyl cellulose, hydroxypropyl cellulose, acrylic resin, fatty acid guanamine wax, oxidized polyethylene, amine salt of high molecular polyester, and linear polyamine hydrazine. Salt of amine and polymeric acid polyester, decylamine solution of polycarboxylic acid, alkyl sulfonate, alkyl allyl sulfonate, gum system ester, polyester resin, phenol resin, melamine resin, epoxy resin , urethane resin and polyimide resin and the pulverizer.

Examples of the tackifier of the inorganic compound include calcium stearate, zinc stearate, aluminum stearate, aluminum oxide, zinc oxide, magnesium oxide, glass, diatomaceous earth, titanium oxide, zirconium oxide, and dioxide. Earthworms, talc, mica, feldspar, kaolinite (kaolin clay), pyrophyllite (waxite clay), sericite, bentonite, bentonite, vermiculite (montmorillonite, beidellite, smectite and saponite) Etc.), organic bentonite and organic montmorillonite.

Commercially available products can also be used as the tackifier. As a commercial product of an organic compound as an enhancer, for example, SELNY-HPC-H, HPC-M, HPC-L, HPC-SL, and HPC-SSL, manufactured by Japan's Soda Co., Ltd., and Mitsubishi Rayon ( DIYANAL BR series, Nippon Kasei Co., Ltd. Dispalone #6900-20X, Dispalone #4200, Dispalone KS-873N and Dispalone #1850, BYK-405 and BYK-410, Rhom & BYK Chem Japan Primal RW-12W manufactured by Haas, AS-AT-20S, AS-AT-350F, AS-AD-10A and AS-AD-160 manufactured by Ito Oil Co., Ltd.

As a commercial product of the tackifier of the inorganic compound, for example, Crown Clay, Bages Clay #60, Bages Clay KF, and Optiwhite of White Rock Industries Co., Ltd., Kaolin JP-100, NN manufactured by Tsuchiya Kaolin Industries Co., Ltd. Kaolin Clay, ST Kaolin Clay and Hardsil, Enjel Hard (ASP), Satenton Plus, TRANSLINK 37 and Highdrasdelami NCD, SY Kaolin, OS CLAY, HA CLAY and MC HARD CLAY, Copchemical Company-made Rusentite SWN, Rusentite SAN, Rusentite STN, Rusentite SEN and Rusentite SPN, Smecton by Cunimina Industries, Bengel, Bengel FW, S Ben, S Ben 74, Oruganite and Oruganite T, Wilba Elis The company's Sui Gaoyin, Oluben, 250M, Benton 34 and Benton38, Japan's Silica Industries (shares) Laponite, Laponite RD and Laponite RDS.

A preferred tackifier from the viewpoint of transparency is a tackifier of the above organic compound, and among them, hydroxypropylcellulose or acrylic resin is also preferred.

One type of the above-mentioned tackifier may be used alone or two or more types may be used in combination.

When the tackifier is used, the content thereof is preferably 0.1 to 10% by mass based on the total solid content of the first composition.

Further, a tackifier may be contained in the second composition described later. At this time, the tackifiers of the first composition and the second composition may be the same and may be different.

(microparticles)

The microparticles are used for the purpose of increasing the hardness of the gradient tilting HC layer.

For example, the fine particles of the hardness-reducing fine particles include a cerium oxide fine particle having a reactive functional group on the surface described in Patent Document 1.

When the fine particles imparting hardness are used, the content thereof is preferably from 5 to 80% by mass based on the mass of the first binder component of the first composition.

(antistatic agent)

The antistatic agent is a component that imparts antistatic properties to the gradient refractive index HC layer.

The antistatic agent is not particularly limited, and a conventionally known one 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 Patent Document 3.

The content of the antistatic agent is not particularly limited, and may be appropriately adjusted and used. For example, the surface resistivity of the gradient-indexed HC layer is preferably 1.0 × 10 ¹³ Ω / □ or less, more preferably 1.0 × 10 ¹¹ Ω / □ or less, and more preferably 1.0 × 10 ⁹ Ω / □ or less. It is particularly preferable that it is 1.0 × 10 ⁸ Ω / □ or less, so that the surface resistivity of the gradient-indexed HC layer can be used in this range.

(leveling agent)

The leveling agent has a function of imparting coatability and/or smoothness to the surface of the gradient-increasing HC layer.

As the leveling agent, a leveling agent such as a fluorine-based, polyfluorene-based or acrylic-based one for a conventionally known antireflection film can be used. For example, a leveling agent which does not have an ionizing radiation curable group, such as the Megafac series (MCF350-5) manufactured by DIC Co., Ltd., or X-22-163A manufactured by Shin-Etsu Chemical Co., Ltd., has an ionizing radiation hardening group. Any of the leveling agents can be used.

When the leveling agent is used, the content thereof is preferably 5.0% by mass or less based on the mass of the first binder component, and more preferably 0.1 to 3.0% by mass.

In the first composition, a component which is arbitrarily used, such as a first binder component and a photopolymerization initiator, is usually prepared by mixing and dispersing the mixture according to a general preparation method. For mixing and dispersing, a paint disperser or a bead mill or the like can be used.

The second composition described later can also be prepared in the same manner.

(curable resin composition for second hard coat layer)

The second composition used in the method for producing an optical film of the present invention contains high refractive index fine particles having an average particle diameter of 1 to 100 nm, a second binder component, and a second solvent, and has a viscosity of 10 to 100 mPa·s. Next, the first composition is applied adjacent to the light-transmitting substrate side as compared with the second composition.

The second composition also has an effect of efficiently increasing the refractive index by obliquely tilting the refractive index of the HC layer to the surface side of the light-transmitting substrate and the vicinity thereof. Thereby, as shown in FIG. 4, a low refractive index layer is provided on the opposite side surface (on the refractive index inclined HC layer) of the light-transmitting substrate of the refractive index-inclined HC layer, and, as shown in FIG. When the high refractive index layer and the low refractive index layer are provided on the gradient inclined HC layer from the side of the refractive index inclined HC layer, the antireflection property of the optical film can be further improved.

Hereinafter, the high refractive index fine particles, the second adhesive component, the second solvent, and other photopolymerization initiators, tackifiers, fine particles, antistatic agents, and the like, which are contained in the second composition, and Leveling agent.

(high refractive index microparticles)

The high refractive index fine particles contained in the second composition of the present invention have an average particle diameter of 1 to 100 nm.

The average particle diameter of the high refractive index fine particles is 100 nm or less from the viewpoint of transparency, and is 1 nm or more from the viewpoint of controlling dispersibility.

The average particle diameter of the high refractive index fine particles is preferably 50 nm or less from the viewpoint of transparency, and more preferably 20 nm or less.

In the method for producing an optical film of the present invention, by setting the viscosity of the first composition and the second composition to a specific range, even if the two compositions are simultaneously applied, the second composition can be suppressed. The high refractive index fine particles are uniformly dispersed in the coating film.

The average particle diameter of the high refractive index microparticles means the average value of 20 particles of the cross section of the cured film (refractive index inclined HC layer) observed by a transmission electron microscope (TEM) photograph, and is once for 1 to 100 nm. Any of the particle size and the secondary particle diameter can be used.

The shape of the high refractive index fine particles is not particularly limited, and materials such as a spherical shape, a chain shape, and a needle shape can be used.

The high refractive index fine particles are not particularly limited as long as the refractive index is 1.50 to 2.80, and conventionally known high refractive index fine particles can be used.

Examples of the high refractive index fine particles include metal oxide fine particles. Specific examples of the metal oxide fine particles include titanium oxide (TiO ₂ , refractive index: 2.71), zirconia (ZrO ₂ , refractive index: 2.10), cerium oxide (CeO ₂ , refractive index: 2.20), and Tin oxide (SnO ₂ , refractive index: 2.00), antimony tin oxide (ATO, refractive index: 1.75 to 1.95), indium tin oxide (ITO, refractive index: 1.95 to 2.00), phosphorus tin compound (PTO, refractive index) : 1.75~1.85), yttrium oxide (Sb ₂ O ₅ , refractive index: 2.04), aluminum zinc oxide (AZO, refractive index: 1.90 to 2.00), gallium zinc oxide (GZO, refractive index: 1.90 to 2.00) and Zinc oxide (ZnSb ₂ O ₆ , refractive index: 1.90 to 2.00) and the like.

The above metal oxide fine particles are also oxidized by tin oxide (SnO ₂ ), antimony tin oxide (ATO), indium tin oxide (ITO), phosphorus tin compound (PTO), antimony oxide (Sb ₂ O ₅ ), aluminum zinc. The material (AZO), gallium zinc oxide (GZO), and zinc antimonate (ZnSb ₂ O ₆ ) are conductive metal oxides, and have the advantage of controlling the diffusion state of the particles, forming a conductive path, and imparting antistatic properties.

In the method for producing an optical film of the present invention, the high refractive index layer or the high refractive index layer provided on the opposite side surface of the light transmissive substrate of the refractive index tilting layer is selected or adjusted to be high in the second composition. The type and content of the refractive index fine particles may be adjusted by adjusting the refractive index of the HC layer.

Specifically, for example, when the low refractive index layer is provided on the opposite side surface of the light-transmitting substrate of the refractive index-inclined HC layer, the refractive index of the refractive index-inclined HC layer is preferably 1.50 to 2.80.

When the refractive index is inclined on the opposite side of the light-transmitting substrate of the HC layer, when the refractive index is inclined on the HC layer side, and the high refractive index layer and the low refractive index layer are provided, the refractive index of the inclined HC layer is higher than that of the high refractive index layer. Low and higher than the low refractive index layer. At this time, for example, the refractive index of the gradient HC layer may have a refractive index of 1.50 to 2.00.

Further, the refractive index of the refractive index is inclined by the refractive index of the HC layer, which means the refractive index of the opposite side interface of the light-transmitting substrate of the refractive index inclined HC layer.

The high-refractive-index fine particles contained in the second composition may be used alone or in combination of two or more kinds of the above-mentioned average particle diameter, shape, refractive index, and material.

(second binder component)

The second binder component is a component that hardens into a matrix of the gradient-increasing HC layer.

The second binder component can be listed using the first binder component.

In addition, a high refractive index of a resin containing an aromatic ring described in Patent Document 3, a resin containing a halogen element such as chlorine, bromine or iodine other than fluorine, and a resin containing an atom such as a sulfur atom, a nitrogen atom or a phosphorus atom may be used. Adhesive ingredients.

The first binder component and the second binder component may be the same and may also be different.

The second binder component may be used alone or in combination of two or more.

(second solvent)

The second solvent can be used as listed for the first solvent.

The first solvent and the second solvent may be the same and may also be different.

The second solvent may be used alone or in combination of two or more.

(other components of the second composition)

The second composition may contain a photopolymerization initiator, a tackifier, or the like for the purpose of promoting the hardening of the second binder component, imparting hardness or antistatic property, etc. in the range of the present invention. Other components such as microparticles, dispersants, antistatic agents, antifouling agents, and leveling agents.

The photopolymerization initiator, the tackifier, and the antistatic agent which may be contained in the second composition may be those described in the above first composition.

The photopolymerization initiator, the tackifier and the antistatic agent contained in the first and second compositions may be the same or different.

(microparticles)

For the purpose of increasing the hardness of the refractive index by tilting the HC layer, cerium oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), or the like can be used as the fine particles contained in the second composition.

(Dispersant)

In order to control the dispersibility of the high refractive index fine particles, a dispersing agent can also be used.

For example, a dispersant having an anionic polar group such as the Disperbyk series manufactured by BYK Chem Japan Co., Ltd. described in Patent Document 3 can be mentioned.

(antifouling agent)

The antifouling agent can further impart scratch resistance to the gradient refractive index HC layer in order to prevent contamination of the outermost surface of the optical film.

As the antifouling agent, a conventionally known antifouling agent (antifouling agent) such as a fluorine compound or a lanthanoid compound can also be used.

The antifouling agent described in Japanese Laid-Open Patent Publication No. 2007-264279 is exemplified as the antifouling agent.

It is also preferable to use an antifouling agent of a commercial product. The antifouling agent (non-reactive) of such a commercially available product is a Megafac series manufactured by DIC Co., Ltd., for example, trade names MCF350-5, F445, F455, F178, F470, F475, F479, F477, TF1025 , such as the TSF series made by Toshiba Silicon Co., Ltd., such as F478 and F178K, the X-22 series and KF series manufactured by Shin-Etsu Chemical Co., Ltd., and the Sailar Plane series of Thiso.

As an antifouling agent (reactivity) of a commercial item, the brand name of the brand name SUA 1900 L10, the brand name SUA 1900 L6, and the name of Eacryl 350 manufactured by Diacel UCB, manufactured by Shinkansen Chemical Industry Co., Ltd., and the trade name are listed. Ebecryl 1360 and trade name KRM7039, UT3971, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name Difenser TF3001, trade name Difenser TF3000, and trade name Difenser TF3028, manufactured by Kyoritsu Chemical Co., Ltd. Light Procoat AFC3000, trade name KNS5300 manufactured by Shin-Etsu Chemical Co., Ltd., trade name UVHC1105 and UVHC8550 manufactured by GE Toshiba Silicone Co., Ltd., and ACS-1122 manufactured by Japan Paint Co., Ltd., etc.

(leveling agent)

As the leveling agent used for the second composition, those enumerated as the above first composition can be used.

When the leveling agent is used, the content thereof is preferably 5.0% by mass or less based on the mass of the second binder component, and more preferably 0.1 to 3.0% by mass.

In the method for producing an optical film of the present invention, after the step (iv), the method further includes (v) forming a low refractive index directly or via the high refractive index layer on the refractive index inclined hard coat layer. The steps of the layer.

By laminating the low refractive index layer in this manner, the antireflection property of the optical film can be further improved.

The layer having a higher refractive index than the gradient refractive index HC layer of the high refractive index layer is provided between the gradient refractive index HC layer and the low refractive index layer, and has an effect of further improving the antireflection property of the optical film.

The high refractive index layer can be formed into a high refractive index layer used in the previously known antireflection film.

For example, it can be formed using a composition containing the high refractive index fine particles, the binder component, and the solvent exemplified above for the gradient refractive index HC layer.

The refractive index of the high refractive index layer may be higher than the refractive index inclined HC layer provided on the light transmissive substrate side of the high refractive index layer.

Further, in the high refractive index fine particles, an antistatic property can be imparted by using a conductive metal oxide.

The film thickness of the high refractive index layer may be appropriately set, and for example, 10 to 300 nm is preferable.

(low refractive index layer)

The low refractive index layer is provided on the opposite side surface of the light-transmitting substrate of the refractive index inclined HC layer or the high refractive index layer, and has an effect of further improving the antireflection property of the optical film.

The refractive index of the low refractive index layer may be lower than the refractive index gradient HC layer and the high refractive index layer, and is preferably 1.49 or less, more preferably 1.47 or less, and particularly preferably 1.42 or less.

The film thickness of the low refractive index layer may be appropriately set, and for example, 10 to 300 nm is preferable.

As the low refractive index layer, a composition of a low refractive index material such as a low refractive index fine particle or a low refractive index resin other than a binder component and a solvent (hereinafter referred to as "a composition for a low refractive index layer" can be used. ")").

As the binder component and the solvent, the high refractive index fine particles and the binder component other than the high refractive index binder and the solvent which are exemplified by the above-mentioned refractive index inclined HC layer can be used.

As the low refractive index fine particles, fine particles (hollow fine particles) having a void described in Patent Document 1 and metal fluoride are preferably used.

The material having the voided fine particles is preferably a ruthenium oxide or a fluororesin for reducing the refractive index of the low refractive index layer.

The average particle diameter of the fine particles having a void is preferably from 5 to 300 nm, and more preferably from 10 to 80 nm.

As the metal fluoride, a conventionally known low refractive index material may be used. For example, LiF (refractive index 1.4), MgF ₂ (magnesium fluoride, refractive index 1.4), 3NaF, AlF ₃ (refractive index 1.4) may be used. AlF ₃ (refractive index 1.4), Na ₃ AlF ₆ (cryolite, refractive index 1.33), and NaMgF ₃ (refractive index 1.36).

The low refractive index resin may, for example, be a curable fluororesin. The curable fluororesin may, for example, be a fluororesin having a photocurable group and/or a thermosetting group.

The photocurable group may, for example, be an ethylenic unsaturated group such as an acryloyl group, a vinyl group or an allyl group, or a polymerizable functional group such as an epoxy group.

Examples of the thermosetting group include a hydroxyl group, a carboxyl group, an amine group, an epoxy group, a glycidyl group, an isocyanate group, and an alkoxy group.

Examples of the curable fluororesin having a photocurable group include vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, perfluorobutadiene, and perfluoro-2,2-dimethyl-1. 3-two A fluoroolefin such as azole.

Further, examples of the curable fluororesin having a photocurable group include 2,2,2-trifluoroethyl (meth)acrylate and 2,2,3,3,3-pentafluoropropene (meth)acrylate. Ester, 2-(perfluorobutyl (ethyl), 2-(perfluorohexyl)ethyl (meth)acrylate, 2-(perfluorooctyl)ethyl (meth)acrylate, ( a (meth) acrylate compound such as 2-(perfluorodecyl)ethyl methacrylate, α-trifluoromethyl methacrylate or α-trifluoromethyl acrylate, having at least 3 molecules in one molecule a fluorine atom having 1 to 14 carbon atoms, a fluorocycloalkyl group or a fluorine alkyl group, and a fluorine-containing polyfunctional (meth) acrylate compound having at least two (meth) acryloxy groups. .

As the curable fluororesin having a thermosetting group, for example, a 4-fluoroethylene-perfluoroalkyl vinyl ether copolymer, a fluoroethylene-hydrocarbon vinyl ether copolymer, an epoxy resin, or a polyurethane resin can be used. , fluorine modified products such as cellulose resin, phenol resin and polyimine resin.

Further, a polymer, a copolymer, and a polyvinylidene fluoride-containing vinylidene fluoride copolymer containing a fluorine atom-containing polymerizable compound described in JP-A-2010-122603 can also be used.

The above-mentioned low refractive index material may be used alone or in combination of two or more.

The content of the low-refractive-index microparticles is preferably 50 to 90% by mass, and more preferably 55 to 70, based on the total mass of the binder component and the low-refractive-index microparticles of the composition for the low-refractive-index layer. quality%.

When the curable fluororesin is used, the content thereof may be appropriately adjusted, and it is preferably 5 to 95% by mass, and more preferably 25 to 60% by mass based on the total solid content of the composition for the low refractive index layer.

In a preferred embodiment of the method for producing an optical film of the present invention, the composition for a low refractive index layer which forms the low refractive index layer is cured, and hollow cerium oxide fine particles are contained. Thereby, there is an advantage that an optical film having more excellent antireflection properties can be obtained.

In the optical film obtained by the method for producing an optical film of the present invention, as described later, in the gradient-inclined HC layer, in the film thickness direction of the gradient-graded HC layer, the amount of the high-refractive-index microparticles is closer to the light penetration. The less the side of the substrate. That is, in the gradient-inclined HC layer, in the film thickness direction of the gradient-graded HC layer, the closer to the low-refractive-index layer-side interface, the more the amount of the high-refractive-index microparticles is present, so the refractive index is inclined to the low refractive index of the HC layer. The refractive index at the interface on the rate layer side and the vicinity thereof are formed by successively coating the HC layer having the same film thickness and containing the same content of the high refractive index fine particles, and the case of forming by the single layer one-time coating method. , can be more efficient. Therefore, by forming a low refractive index layer formed by curing a low refractive index layer containing hollow cerium oxide fine particles on the refractive index inclined HC layer, the low refractive index layer of the refractive index inclined HC layer can be increased. The interface portion on the side has a difference in refractive index from the low refractive index layer, and an optical film having excellent antireflection properties is obtained.

In another preferred embodiment of the method for producing an optical film of the present invention, the composition for forming a low refractive index layer of the low refractive index layer is cured, and at least one selected from the group consisting of a metal fluoride and a curable fluororesin is selected. One type of low refractive index material. In the case where the composition for a low refractive index layer contains a fluorine-based low refractive index material as a low refractive index material, there is an advantage that an optical film having sufficient antireflection properties can be obtained.

A fluorine-based low refractive index material such as a metal fluoride or a curable fluororesin has a lower refractive index than the hollow ceria particles, so that the effect of lowering the refractive index of the low refractive index layer is smaller than that of the hollow ceria particles.

An optical film composed of a layer of a low refractive index layer/high refractive index layer (high refractive index HC layer)/substrate formed by successive coating and single layer coating. As described above, since the refractive index of the low refractive index layer side interface and the vicinity thereof of the high refractive index layer (high refractive index HC layer) cannot be efficiently increased, the fluorine-based low refractive index is used in the composition for forming the low refractive index layer. At the rate of material, sufficient anti-reflection properties cannot be obtained. Further, even if the refractive index of the low refractive index layer side interface and the vicinity thereof of the high refractive index layer (high refractive index HC layer) can be increased by the previous sequential coating, the high refractive index layer (high refractive index HC layer) is also used. A layer interface occurs between the substrate or the substrate side layer of the layer, and interference fringes occur.

In contrast, according to the above preferred embodiment of the method for producing an optical film of the present invention, as described above, the refractive index of the low refractive index layer side interface of the refractive index tilting HC layer and its vicinity can be efficiently increased, and Since the occurrence of interference fringes can be suppressed, even if a fluorine-based low refractive index material is used for the composition for a low refractive index layer, an optical film having sufficient antireflection properties can be obtained.

In another preferred embodiment of the method for producing an optical film of the present invention, the composition for forming a low refractive index layer of the low refractive index layer is hardened, and does not contain hollow ceria particles, but contains metal fluoride and hardens. At least one low refractive index material is selected from the group consisting of fluororesins. When the composition for a low refractive index layer does not contain hollow ceria particles, and the fluorine-based low refractive index material is used as a low refractive index material, it has the advantage that sufficient both antireflection and alkali resistance can be established. .

When the polarizing plate is bonded to the optical film on one side of the polarizing element, the optical film is immersed in an alkali solution, and the substrate side surface of the optical film is hydrophilized (hereinafter referred to as "alkaline treatment". "). However, in the case where the outermost layer of the optical film contains cerium oxide microparticles (hollow cerium oxide microparticles), the hollow cerium oxide microparticles are detached from the outermost layer by alkalization treatment, and have an easy flow or dissolution in the alkali The nature of the solution.

When the optical film having the low refractive index layer containing the hollow cerium oxide fine particles on the outermost surface is alkalized, if the hollow cerium oxide fine particles are detached by alkalization treatment, the content of the hollow cerium oxide fine particles is reduced, so that it is low. The refractive index of the refractive index layer is increased, and there is a possibility that the desired antireflection property cannot be obtained. Further, if the hollow cerium oxide fine particles are discharged or dissolved in the alkali solution, there is a flaw in the contaminated alkali solution.

In the case where the optical film having low alkali resistance is alkalized, a protective film is attached to the outermost layer (low refractive index layer) containing cerium oxide fine particles (hollow cerium oxide fine particles), and the outermost layer is applied. The (low refractive index layer) is protected by an alkalized alkali solution. However, in the method of attaching the protective film and removing the protective film after the alkalizing treatment, the number of steps and the cost of the protective film are increased, and the manufacturing cost of the optical film is increased.

In contrast, according to the above preferred embodiment of the method for producing an optical film of the present invention, as described above, since the refractive index of the low refractive index layer side interface and the vicinity thereof of the refractive index tilting HC layer can be efficiently increased, When the composition for a low refractive index layer does not contain hollow ceria particles and contains a fluorine-based low refractive index material, an optical film having sufficient antireflection properties and alkali resistance can be obtained.

Therefore, in the case where the optical film of the above preferred embodiment is subjected to alkalization treatment, the protective film is not required, and the number of steps and the manufacturing cost can be reduced.

The photopolymerization initiator and the antifouling agent exemplified above for the gradient refractive index HC layer may be contained in the low refractive index layer.

As described above, the low refractive index layer and the high refractive index layer may be formed by coating a composition containing a binder component and a solvent with a hard coat layer. Further, the low refractive index layer and the high refractive index layer may be formed by a vapor phase method (or a dry coating method) such as vacuum deposition, sputtering, plasma CVD, or ion plating.

In the method for producing an optical film of the present invention, the step (i) and the step (iii) may further comprise (vi) forming a refractive index oblique hard coat surface on the light-transmitting substrate. The step of the antistatic layer.

By providing an antistatic layer, the antistatic property of the optical film can be further improved.

The antistatic layer can be formed using a composition containing an antistatic agent, a binder component, and a solvent.

As the antistatic agent, those exemplified by the above-mentioned refractive index inclined HC layer can be used.

The content of the antistatic agent is preferably from 50 to 400% by mass based on the mass of the binder component of the composition forming the antistatic layer.

As the binder component and the solvent contained in the composition of the antistatic layer, the binder component and the solvent exemplified by the above-mentioned refractive index gradient HC layer can be used.

In the method for producing an optical film of the present invention, in the range in which the antireflection property of the optical film is not impaired, it may be included in the outermost surface of the optical film having the gradient of the refractive index of the HC layer (the light penetrating base of the optical film) The opposite side of the material), the step of further providing an antifouling layer.

When an antifouling layer is provided on the outermost surface, the optical film can be provided with antifouling properties, scratch resistance, and the like.

The antifouling layer can be formed using a composition containing an antifouling agent, a binder component, and a solvent.

As the antifouling agent, a leveling agent and an antifouling agent exemplified as the above-mentioned refractive index inclined HC layer can be used.

The content of the antifouling agent can be appropriately adjusted according to the required performance.

As the binder component and the solvent contained in the composition forming the antifouling layer, a binder component and a solvent other than the high refractive index binder component exemplified by the above-mentioned refractive index gradient HC layer can be used.

The film thickness of the antifouling layer may be appropriately set, and for example, 10 to 300 nm is preferable.

In the step (iii) of the method for producing an optical film of the present invention, the method of simultaneously coating the first composition and the second composition is not particularly limited, and a conventionally known simultaneous coating method can be used.

Examples of the simultaneous coating method include a die coating and a sliding coating having two or more slits (discharge ports).

Fig. 2 is a schematic view showing an example of a simultaneous coating method using an extrusion type die coater.

The curable resin composition 60 for the first hard coat layer and the curable resin composition for the second hard coat layer are respectively formed on the light-transmitting substrate 10 by the slits 51 and 52 of the die coater head portion 40. In the case of the light-permeable substrate, the coating film 61 and the second coating of the curable resin composition for the first hard coat layer are formed adjacent to each other and applied at the same time as the curable resin composition 60 for the first hard coat layer. A coating film 71 of a curable resin composition for a hard coat layer. In addition, in FIG. 2, the first hard coat layer curable resin composition and the second hard coat layer curable resin composition are integrally formed into one hard coat layer, but the two compositions are conveniently described. It is separated from the color of the coating film.

Further, the wet film thickness of the first composition and the second composition at the time of application may be appropriately adjusted depending on the desired properties.

When the wet film thickness of the first composition is set to T1 and the wet film thickness of the coating film of the second composition is T2, T2/T1 (ie, T2÷T1) is 0.01 to 1, and the refractive index is inclined to the HC layer. In the film thickness direction, the region from the surface side interface of the light-transmitting substrate to the dry film thickness of the refractive index-inclination HC layer is 70%, and 70 to 100% of the total amount of the high-refractive-index particles is easily distributed, and the efficiency is high. It is preferable to control the distribution of the high refractive index fine particles.

Further, the wet film thickness can be determined from the conveyance speed and area of the object to be coated and the discharge amount of the composition.

In the step (iv) of the method for producing an optical film of the present invention, ultraviolet light, visible light, electron beam or ionizing radiation or the like is mainly used for light irradiation. In the case of ultraviolet curing, ultraviolet rays generated by light such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc lamp, a xenon arc lamp, or a metal halide lamp can be used. The amount of light irradiation may be 50 to 300 mJ/cm ^{2 in terms} of an integrated exposure amount of an ultraviolet wavelength of 365 nm.

Further, in the step (iv), it may be appropriately dried before the light irradiation as needed. Examples of the drying method include a method of drying under reduced pressure or heating, and a method of combining the drying. Further, it is preferably dried at 30 to 110 ° C in the case of drying under normal pressure. For example, when methyl isobutyl ketone is used as the first or second solvent, it is usually at a temperature ranging from room temperature to 80 ° C, preferably from 40 ° C to 70 ° C, for 20 seconds to 3 minutes, preferably Dry for about 30 seconds to 1 minute.

(iv) The refractive index of the HC layer formed in the step may be appropriately adjusted according to the required hardness, antireflection property, and the like. The film thickness of the gradient refractive index HC layer may be, for example, 1 to 20 μm.

(optical film)

The first optical film of the present invention is characterized by the method of producing the optical film described above.

The second optical film of the present invention is an optical film having at least one refractive index oblique hard coat layer on one side of the light-transmitting substrate, wherein the refractive index oblique hard coat layer has an average particle diameter of 1 to 100 nm. The high refractive index fine particles, and in the refractive index oblique hard coat layer, the amount of the high refractive index fine particles is less toward the light transmissive substrate side in the film thickness direction of the gradient refractive index hard coat layer.

3 is a cross-sectional view schematically showing an example of a layer configuration of an optical film of the present invention and a distribution of high refractive index fine particles in a film thickness direction in a refractive index gradient HC layer.

In FIG. 3, the optical film 1 is provided with a refractive index oblique hard coat layer 20 on the light-transmitting substrate 10. Next, in the refractive index-inclined hard coat layer 20, the amount of the high refractive index fine particles is less toward the light-transmitting substrate side in the film thickness direction of the gradient refractive index hard coat layer.

Fig. 4 is a cross-sectional view schematically showing another example of the layer constitution of the optical film of the present invention. In addition, in order to simplify the description, in FIGS. 4 to 6, the high refractive index fine particles in the refractive index gradient HC layer are omitted.

On the light-transmitting substrate 10, a refractive index oblique hard coat layer 20 and a low refractive index layer 80 are sequentially provided from the side of the light-transmitting substrate.

In the above method for producing an optical film, after the step (iv), the step of directly forming the low refractive index layer on the refractive index oblique hard coat layer is further provided, and an optical film having such a layer can be obtained. .

Fig. 5 is a cross-sectional view schematically showing another example of the layer constitution of the optical film of the present invention.

On the light-transmitting substrate 10, a refractive index oblique hard coat layer 20, a high refractive index layer 90, and a low refractive index layer 80 are sequentially provided from the light-transmitting substrate side.

In the method for producing an optical film described above, after the step (iv), the step of forming a low refractive index layer on the refractive index oblique hard coat layer and the high refractive index layer is further provided. An optical film composed of a seed layer.

Fig. 6 is a cross-sectional view schematically showing another example of the layer constitution of the optical film of the present invention.

On the light-transmitting substrate 10, an antistatic layer 100, a refractive index-increasing hard coat layer 20, a high refractive index layer 90, and a low refractive index layer 80 are sequentially provided from the light-transmitting substrate side.

In the above method for producing an optical film, between (i) step and (iii), a step (vi) of forming an antistatic layer on the surface of the light-transmitting substrate at which the refractive index is inclined to the hard coat layer is further provided An optical film of such a layer can be obtained. By providing an antistatic layer, the optical film can be provided with antistatic properties.

The first optical film of the present invention, as described above, has a first composition containing high refractive index fine particles not containing a specific viscosity and a second composition containing high refractive index fine particles having a specific viscosity, and has the two compositions In the gradient-inclination HC layer in which the first composition is adjacent to the light-transmitting substrate side and coated at the same time as the second composition, the refractive index is inclined at the HC layer. The film thickness direction of the layer, the closer the high refractive index particles are to the side of the light penetrating substrate. Therefore, in the light transmissive substrate side interface of the gradient refractive index HC layer, interference fringes due to the difference in refractive index between the high refractive index microparticles and the lower layer such as the light transmissive substrate or the antistatic layer can be suppressed, and The optical film is excellent in appearance.

Further, since the high refractive index fine particles are not uniformly distributed in the gradient refractive index HC layer and are distributed on the upper layer side, the refractive index can be made to have a high refractive index on the opposite side surface of the light-transmitting substrate of the HC layer. Therefore, when the low refractive index layer is provided on the opposite side surface side of the light-transmitting substrate of the refractive index-inclined HC layer as shown in FIGS. 4 and 5, the antireflection property of the optical film can be improved.

In a preferred embodiment of the optical film of the present invention, the low refractive index layer contains hollow ceria particles. Thereby, there is an advantage that the optical film has excellent antireflection properties.

In the optical film of the present invention, as shown in FIG. 3, in the gradient-inclined HC layer, in the film thickness direction of the gradient-graded HC layer, the portion closer to the interface of the low-refractive-index layer side, the presence of high-refractive-index microparticles The larger the amount, the higher the refractive index of the low-refractive-index layer side interface of the refractive index-inclination HC layer and its vicinity. In the case where the low-refractive-index layer on the gradient-inclination HC layer contains hollow ceria particles, the difference in refractive index between the interface portion on the low-refractive-index layer side of the refractive index-inclined HC layer and the low-refractive-index layer is large, and the optical The film has excellent antireflection properties.

In another preferred embodiment of the optical film of the present invention, even if the low refractive index layer contains at least one low refractive index component selected from the group consisting of a metal fluoride and a fluororesin, A reflective optical film is sufficiently prevented.

In another preferred embodiment of the optical film of the present invention, the low refractive index layer does not contain hollow ceria particles, and contains at least one low refractive index selected from the group consisting of metal fluorides and fluororesins. The composition is preferable in terms of sufficient prevention of reflectance and alkali resistance. Further, when the optical film of the preferred embodiment is used, a protective film is not required in the alkalization treatment, and the polarizing plate can be produced at low cost.

The low refractive index layer, the high refractive index layer, the antistatic layer, and the antifouling layer which are suitably provided in the optical film of the present invention have been described in the method for producing an optical film, and thus the description thereof will be omitted.

In a preferred embodiment of the optical film of the present invention, in the refractive index oblique hard coat layer, the surface of the light-transmitting substrate opposite to the surface side until the refractive index is inclined to 70% of the film thickness of the hard coat layer In the above, 90% or more of the total amount of the high refractive index fine particles is present.

As shown in FIG. 3, in the region where the refractive index is inclined, the refractive index of the light-transmitting substrate from the surface side interface to the light-transmitting substrate side is inclined to 70% of the film thickness of the HC layer. 90% or more of the high refractive index fine particles are present, and the high refractive index fine particles existing at the light transmissive substrate side interface of the refractive index inclined HC layer are less, and the refractive index tilting HC layer and the light transmissive substrate are further suppressed. Interference fringes between the antistatic layers occur.

Further, although FIG. 3 is taken as an example, the distribution of the high refractive index fine particles in the refractive index inclined HC layer may be formed by providing other layers as shown in FIGS. 4 to 6.

In the optical film of the present invention, in the above-mentioned refractive index oblique hard coat layer, a tackifier may be formed in the vicinity of the interface on the side of the light-transmitting substrate, and the refractive index inclined hard coat layer may be entirely Contains the appearance of a tackifier.

As described above, when the first composition for forming the gradient-inclination HC layer contains the tackifier for adjusting the viscosity, the refractive index is inclined to the vicinity of the interface of the light-transmitting substrate side of the HC layer because it is mainly composed of Since the composition is formed, it becomes contained in this region.

Further, when both the first composition and the second composition contain a tackifier, the viscosity-increasing HC layer contains a tackifier.

[Examples]

Hereinafter, the present invention will be described more specifically by way of examples. The invention is not limited by this description.

As the high refractive index fine particle sol (1), an isopropyl alcohol dispersion of ZnSb ₂ O ₆ manufactured by Nissan Chemical Industries Co., Ltd., trade name CX-Z210IP-F2 (average particle diameter: 15 nm, solid content 20% dispersion) was used. .

As the high refractive index granule sol (2), a PTO: phosphoric acid-doped tin oxide-containing isopropyl alcohol dispersion manufactured by Nissan Chemical Industries Co., Ltd., trade name CX-S303IP (average particle diameter 15 nm, solid content 30% dispersion liquid) was used. ).

As the high refractive index fine particle sol (3), a MEK dispersion of ZrO ₂ manufactured by Nissan Chemical Industries Co., Ltd., trade name OZ-S30K (average particle diameter: 10 nm, solid content: 30% dispersion) was used.

As the low refractive index fine particles, hollow ceria fine particles (average primary particle diameter: 50 nm, solid content: 20%, void ratio: 40%) were used.

As the metal fluoride, a cryolite (Na ₃ AlF ₆ ) manufactured by CI Chemical Co., Ltd., and a solid 15% MIBK solution were used.

As the binder component (1), a polyfunctional urethane acrylate manufactured by Shin-Nakamura Chemical Co., Ltd., trade name U-4HA (molecular weight 600, functional group number 4) was used.

As the binder component (2), a product name KAYARAD-DPHA (a mixture of DPPA (dipentaerythritol pentaacrylate: 5-functional) and DPHA (dipentaerythritol hexaacrylate: 6-functional)) manufactured by Nippon Kayaku Co., Ltd. was used.

As the binder component (3), pentaerythritol triacrylate manufactured by Nippon Kayaku Co., Ltd. was used.

As the binder component (4), the trade name LINC-3A (fluorinated monomer) manufactured by Kyoeisha Chemical Industry Co., Ltd. is used.

As the solvent (1), methyl ethyl ketone which is impregnated with the TAC substrate is used.

As the solvent (2), isopropyl alcohol which does not have permeability to the TAC substrate is used.

As the solvent (3), methyl isobutyl ketone was used.

As the tackifier, Selney HPC-M (hydroxypropylcellulose) manufactured by Nippon Soda Co., Ltd. was used.

As the photopolymerization initiator (1), trade name IRGACURE 184 manufactured by Ciba Specialty Chemicals Co., Ltd. was used.

As the photopolymerization initiator (2), trade name IRGACLRE 127 manufactured by Ciba Specialty Chemicals Co., Ltd. was used.

As the antifouling agent, X-22-164E (reactive polyxanthoxy antifouling agent) manufactured by Shin-Etsu Chemical Co., Ltd. was used.

As the light-transmitting substrate, a TAS substrate made of a Coats wafer (trade name), trade name: TF 80UL (thickness: 80 μm, refractive index: 1.47) was used.

The abbreviations of the respective compounds are as follows.

IPA: isopropanol

MEK: methyl ethyl ketone

MIBK: methyl isobutyl ketone

PETA: pentaerythritol triacrylate

TAC: triacetyl cellulose

(modulation of composition)

The composition was prepared by mixing the components of the composition shown below.

(curable resin composition for the first hard coat layer 1, viscosity 5.3 mPa ‧ s)

Adhesive composition (1) U-4HA: 20 parts by mass

Adhesive composition (2) KAYARAD-DPHA: 30 parts by mass

Solvent (1) MEK: 37.5 parts by mass

Solvent (2) IPA: 12.5 parts by mass

Photopolymerization initiator (1) IRGACURE 184: 2 parts by mass

(The curable resin composition for the second hard coat layer 1 has a viscosity of 25.7 mPa ‧ s)

High refractive index microparticle sol (1) CX-Z210 IP-F2: 83.3 parts by mass

Adhesive composition (1) U-4HA: 8.3 parts by mass

Solvent (1) MEK: 8.4 parts by mass

Photopolymerization initiator (1) IRGACURE 184: 0.3 parts by mass

(The curable resin composition for the second hard coat layer 2, viscosity 15.1 mPa‧s)

High refractive index microparticle sol (2) CX-S303IP: 66.6 parts by mass

Adhesive composition (1) U-4HA: 20.0 parts by mass

Solvent (1) MEK: 13.4 parts by mass

Photopolymerization initiator (1) IRGACURE 184: 0.8 parts by mass

(The curable resin composition 2 for the second hard coat layer, viscosity 28.5 mPa‧s)

High refractive index microparticle sol (2) CX-S303IP: 87.5 parts by mass

Adhesive composition (1) U-4HA: 8.7 parts by mass

Solvent (1) MEK: 3.8 parts by mass

Photopolymerization initiator (1) IRGACURE 184: 0.4 parts by mass

Tackifier by propyl cellulose: 0.2 parts by mass

(Curable resin composition 4 for second hard coat layer, viscosity 24.2 mPa‧s)

High refractive index microparticle sol (3) OZ-S30K: 87.5 parts by mass

Adhesive composition (1) U-4HA: 8.7 parts by mass

Solvent (1) MEK: 3.8 parts by mass

Photopolymerization initiator (1) IRGACURE 184: 0.4 parts by mass

Tackifier by propyl cellulose: 0.3 parts by mass

(Composition for high refractive index layer)

High refractive index microparticle sol (1) CX-Z210IP-F2: 28.6 parts by mass

Adhesive composition (3) PETA: 2.3 parts by mass

Solvent (3) MIBK: 69.1 parts by mass

Photopolymerization initiator (2) IRGACURE 127: 0.1 parts by mass

(Composition for low refractive index layer 1)

Hollow ceria microparticles: 15.0 parts by mass

Adhesive composition (3) PETA: 1.0 parts by mass

Adhesive composition (4) LINC-3A: 1.0 parts by mass

Solvent (3) MIBK: 83.0 parts by mass

Photopolymerization initiator (2) IRGACURE 127: 0.1 parts by mass

(Composition 2 for low refractive index layer)

Adhesive composition (4) LINC-3A: 3.0 parts by mass

Photopolymerization initiator (2) IRGACURE 127: 0.15 parts by mass

Antifouling agent X-22-164E: 0.06 parts by mass

Solvent (3) MIBK: 96.91 parts by mass

(Composition 3 for low refractive index layer)

Metal fluoride (cryolite): 10 parts by mass

Adhesive composition (3) PETA: 0.5 parts by mass

Adhesive composition (4) LINC-3A: 0.5 parts by mass

Photopolymerization initiator (2) IRGACURE 127: 0.05 parts by mass

Antifouling agent X-22-164E: 0.05 parts by mass

Solvent (3) MIBK: 88.9 parts by mass

(Example 1)

The first composition 1 and the second composition are used on the TAC substrate by using a 2-grooved plate applicator such that the first composition 1 is located on the substrate (lower layer) side than the second composition 1 The composition 1 was applied at the same time at a coating speed of 20 m/min to form a coating film. The coating film was dried for 30 seconds to remove the solvent. Next, this coating film was irradiated with ultraviolet rays at an irradiation amount of 80 mJ/cm ² using an ultraviolet irradiation device, and the coating film was cured to form a refractive index inclined HC layer having a dry film thickness of 12 μm.

Next, the composition 1 for the low refractive index layer is coated on the HC layer with a refractive index, and the coating film is formed by using a grooved plate. The coating film was dried with the refractive index-slanted HC layer and irradiated with ultraviolet rays to form a low refractive index layer having a dry film thickness of 100 nm, and an optical film having a refractive index-inclined HC layer and a low refractive index layer on a TAC substrate was produced.

(Example 2)

In Example 1, except that the second composition 2 was used instead of the second composition 1, an optical film having a refractive index inclined HC layer and a low refractive index layer formed on a TAC substrate was treated in the same manner as in Example 1.

(Example 3)

In Example 2, except that 0.5 parts by mass of a tackifier (Selney HPC-M) was added to the first composition 1 to adjust the viscosity to 14.8 mPa ‧ , the same treatment as in Example 2 was carried out on a TAC substrate. The optical film of the HC layer and the low refractive index layer is inclined.

(Example 4)

In Example 1, except that 1.0 part by mass of a tackifier (Selney HPC-M) was added to the first composition 1 to adjust the viscosity to 20.4 mPa‧s, and the second composition 3 was used instead of the second composition 1. An optical film having a refractive index inclined HC layer and a low refractive index layer formed on a TAC substrate was treated in the same manner as in Example 1.

(Example 5)

In Example 1, an optical film having a refractive index-inclined HC layer and a low refractive index layer on a TAC substrate was produced in the same manner as in Example 1 except that the second composition 4 was used instead of the second composition 1.

(Example 6)

In Example 5, except that 1.0 part by mass of a tackifier (Selney HPC-M) was added to the first composition 1 to adjust the viscosity to 20.4 mPa ‧ , the same treatment as in Example 5 was carried out on a TAC substrate. The optical film of the HC layer and the low refractive index layer is inclined.

(Example 7)

The same procedure as in Example 1 was carried out until the formation of the refractive index tilting HC layer.

Next, the composition for the high refractive index layer was coated on the HC layer with a grooved plate to form a coating film. The coating film was dried with the refractive index-slanted HC layer and irradiated with ultraviolet rays to form a high refractive index layer having a dry film thickness of 160 nm.

Next, on the high refractive index layer, the low refractive index layer composition 1 was applied using a grooved plate to form a coating film. The coating film was dried with the refractive index-slanted HC layer and irradiated with ultraviolet rays to form a low refractive index layer having a dry film thickness of 100 nm, and was formed on a TAC substrate having a refractive index-inclined HC layer, a high refractive index layer, and a low refractive index layer. Optical film.

(Example 8)

The same procedure as in Example 5 was carried out until the formation of the refractive index tilting HC layer.

Next, the composition for low refractive index layer 2 was coated on the HC layer with a refractive index, and the coating film was formed by using a grooved plate. The coating film was dried with the refractive index-slanted HC layer and irradiated with ultraviolet rays to form a low refractive index layer having a dry film thickness of 100 nm, and an optical film having a refractive index-inclined HC layer and a low refractive index layer on a TAC substrate was produced.

(Example 9)

In Example 8, except that the composition 3 for the low refractive index layer was used instead of the composition 2 for the low refractive index layer, the same procedure as in Example 8 was carried out to produce a gradient refractive index HC layer and a low refractive index layer on a TAC substrate. Optical film.

(Comparative Example 1)

In Example 5, MEK was added to the second, except that the ratio of the unmodified MEK to the IPA was used and the two mixed solvents were added to the first composition 1 to adjust the viscosity of the first composition 1 to 1.2 mPa ‧ s. The composition 4 and the viscosity of the second composition 4 were adjusted to 2.5 mPa ‧ s, and treated in the same manner as in Example 5 to prepare an optical film having a gradient refractive index HC layer and a low refractive index layer on a TAC substrate.

(Comparative Example 2)

In Example 1, except that 10.0 parts by mass of a tackifier (Selney HPC-M) was added to the first composition 1, and the ratio of MEK to IPA of the first composition 1 was not changed and the two were mixed. The amount of the solvent was reduced, the viscosity of the first composition 1 was adjusted to 109.5 mPa‧s, and 5.0 parts by mass of the tackifier (Selney HPC-M) was added to the second composition 1, and the second composition was not changed. The solvent of the substance 1 was reduced in amount and the optical viscosity of the second composition 2 was adjusted to 110.3 mPa ‧ s. An optical film having a refractive index gradient HC layer and a low refractive index layer on a TAC substrate was prepared in the same manner as in Example 1.

(Comparative Example 3)

In Example 1, except that the ratio of the unmodified MEK to the IPA was used and the two mixed solvents were added to the first composition 1, the viscosity of the first composition 1 was adjusted to 1.2 mPa ‧ s, as in Example 1. The optical film having a gradient refractive index HC layer and a low refractive index layer on a TAC substrate was prepared.

(Comparative Example 4)

In Example 1, except that 10.0 parts by mass of a tackifier (Selney HPC-M) was added to the first composition 1, and the ratio of MEK to IPA of the first composition 1 was not changed and the two were mixed. The amount of the solvent was reduced, and the viscosity of the first composition 1 was adjusted to 109.5 mPa ‧ s. An optical film having a refractive index gradient HC layer and a low refractive index layer on a TAC substrate was prepared in the same manner as in Example 1.

(Comparative Example 5)

In Example 5, except that the tackifier was not used in the second composition 4, and the viscosity was adjusted to 2.5 mPa ‧ s, it was treated in the same manner as in Example 5 to have a gradient refractive index HC layer on the TAC substrate. An optical film of a low refractive index layer.

(Comparative Example 6)

In Example 1, except that 5.0 parts by mass of a tackifier (Selney HPC-M) was added to the second composition 1, and the amount of the solvent of the second composition 1 was decreased and the viscosity was adjusted to be 110.3 mPa·s. An optical film having a refractive index inclined HC layer and a low refractive index layer formed on a TAC substrate was treated in the same manner as in Example 1.

(Comparative Example 7)

The first composition 1 was coated on a TAC substrate using a grooved plate to form a coating film. The coating film was dried for 30 seconds to remove the solvent. Next, this coating film was irradiated with ultraviolet rays at an irradiation amount of 80 mJ/cm ² using an ultraviolet irradiation device, and the coating film was cured to form an HC layer having a dry film thickness of 12 μm.

Next, on the HC layer, the composition 1 for the low refractive index layer was coated with a grooved plate to form a coating film. The coating film was dried with the HC layer and irradiated with ultraviolet rays to form a low refractive index layer having a dry film thickness of 100 nm, and an optical film having an HC layer and a low refractive index layer containing no high refractive index fine particles on the TAC substrate was produced.

(Comparative Example 8)

In Comparative Example 7, except that the composition 3 for the low refractive index layer was used instead of the composition 1 for the low refractive index layer, the same treatment as in Comparative Example 7 was carried out to prepare an HC layer having no high refractive index fine particles on the TAC substrate. An optical film of a low refractive index layer.

(Comparative Example 9)

On the TAC substrate, the first composition 1 was applied using a grooved plate applicator, and the coating film was dried in a hot oven at 70 ° C for 30 seconds to remove the solvent. Then, this coating film was irradiated and cured by irradiation with an ultraviolet irradiation device at an irradiation amount of 50 mJ/cm ^{2 to} form an HC layer containing no high refractive index fine particles having a thickness of 7 μm. Next, on the HC layer, the second composition 1 was coated using a grooved plate applicator, and the coating film was dried in a hot oven at 70 ° C for 30 seconds to remove the solvent. Then, the coating film was irradiated with an ultraviolet irradiation device at an irradiation dose of 100 mJ/cm ^{2 to} form an HC layer containing high refractive index fine particles, and an HC layer having a total thickness of 11 μm was formed.

Next, on the HC layer, the low refractive index layer having a dry film thickness of 100 nm was formed in the same manner as in Example 1 using the composition 1 for the low refractive index layer, and was formed on the TAC substrate, and was not contained on the TAC substrate side. An optical film of an HC layer of high refractive index microparticles, an HC layer containing high refractive index microparticles, and a low refractive index layer.

(Comparative Example 10)

In Comparative Example 9, except that the composition 2 for the low refractive index layer was used instead of the composition 1 for the low refractive index layer, it was processed on the TAC substrate in the same manner as in Comparative Example 9, and was formed from the TAC substrate side. An optical film of an HC layer of high refractive index microparticles, an HC layer containing high refractive index microparticles, and a low refractive index layer.

The types, viscosity, application method, wet film thickness, and other composition used in the first and second compositions of the above examples and comparative examples are shown in Table 1.

[Table 1]

(Evaluation of optical film)

The optical films of the above examples and comparative examples were each measured for reflectance as shown below. The optical films of the above-described examples and comparative examples were subjected to interference fringes, adhesion, planarity (with or without coating), distribution of high refractive index fine particles, and productivity (suitability and simplicity). )evaluation of. Further, regarding Examples 8 and 9, and Comparative Examples 7 to 10, evaluation of alkali resistance was performed. The results are shown in Table 2.

(Measurement of reflectance)

The measurement of the reflectance was carried out by using the product name V7100 ultraviolet visible light spectrophotometer manufactured by JASCO Corporation and the product name VAR-7010 absolute reflectance measuring device manufactured by JASCO Corporation. The incident angle was 5° and the polarizer was used. The N-polarized light was measured at a wavelength range of 380 to 780 nm, and a black tape was attached to the TAC substrate side of the optical film, and the device was placed in a device for measurement. Further, the average value of the measurement results obtained by measuring the wavelength range was defined as the reflectance.

(Evaluation of interference fringes)

An interference fringe inspection lamp (Na lamp) manufactured by Naftec Co., Ltd. was used for visual inspection and evaluated on the basis of the following criteria.

○: The occurrence of interference fringes was hardly observed at all.

╳: Obviously observe the interference fringe

(evaluation of adhesion)

With respect to the optical films of the above examples and comparative examples, the adhesion ratio of the transverse disk adhesion test shown below was measured.

(checkerboard adhesion test)

A total of 100 cells of the base plate were placed in the 1 mm square of the low refractive index layer side surface of the optical film, and 5 continuous peeling tests were carried out using a 24 mm Cello-Tape (registered trademark) manufactured by Nichiban Co., Ltd., and based on the following criteria. Calculate the ratio of the undivided residual component.

Adhesion rate (%) = (number of undivided parts / total number of parts of 100) × 100

(evaluation of the surface)

Regarding the appearance of the optical film (with or without coating), it was evaluated visually.

○: No coating pattern was observed

△: Obscured to observe the coating pattern

╳: Clearly observed the coated pattern

(Distribution of high refractive index fine particles in the gradient refractive index HC layer)

The cross section of the optical film was observed by a TEM photograph, and the film thickness ratio from the side of the low refractive index layer side occupied by 90% of the total amount of the high refractive index fine particles in the gradient gradient HC layer or the HC layer was determined.

(productive (suitable coating))

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 on the basis of the following criteria.

○: even if the coating speed is 10 m/min or more, the coating pattern can be applied without coating.

△: The coating speed at which coating coating is not applied is 1 m/min or less.

╳: Anyone who produces a coating at any speed

(alkali resistance)

The optical film was placed in a 2 N aqueous solution of sodium hydroxide at 55 ° C and immersed for 2 minutes. Next, after sufficiently washing with water, it was dried at 70 ° C for 5 minutes. Next, steel wool of #0000 was used, rubbed back and forth for 10 times with a friction load of 0.98 N (100 gf), and the presence or absence of damage or peeling of the low refractive index layer was visually observed and evaluated on the following basis.

○: no damage and peeling on the low refractive index layer

╳: damage or flaking on the low refractive index layer

Further, from the results of the reflectance obtained and the refractive index of the optical films of Examples 1 to 9 and Comparative Examples 1 to 6, the HC layer was measured, and the amount of the high refractive index fine particles in the film thickness direction was measured by XPS. It was confirmed that any of the refractive index-sloping HC layers was from the interface on the low refractive index layer side toward the interface on the TAC substrate side, and the refractive index was continuously lowered.

In the above Examples and Comparative Examples, in Examples 1 to 9 and Comparative Examples 1 to 6 which were simultaneously coated, the number of steps was small, and the production of an optical film can be easily performed.

However, in Comparative Examples 9 and 10 in which the coating was successively applied, the coating of the composition and the hardening step of the light irradiation were inferior in terms of simplicity.

[Table 2]

(summary of results)

From Table 2, the optical films of Examples 1 to 7 and Comparative Examples 1 to 6 and 9 achieved good reflectance. In particular, Example 7 in which the layers of the refractive index-inclined HC layer, the high refractive index layer, and the low refractive index layer were formed had a low reflectance.

In the optical films of Examples 8 and 9 in which a fluorine-based low refractive index material was used for the composition for a low refractive index layer, the reflectances were 1.01 and 0.75, respectively, and sufficient antireflection properties were obtained. In particular, the optical film of Example 9 did not contain hollow ceria particles, and even if a fluorine-based low-refractive material was used, the reflectance was lower than that of Comparative Example 7 using hollow ceria particles. When the optical film of Example 9 was compared with the optical film of Comparative Example 10, both had the same low refractive index layer and contained high refractive index fine particles in the HC layer adjacent to the low refractive index layer, but Example 9 was used. The optical film has a low reflectance. It is presumed that the optical film of Example 9 is inclined in the HC layer with a refractive index, and the refractive index is increased in the vicinity of the interface on the side of the low refractive index layer. Therefore, Comparative Example 10 in which the high refractive index fine particles are uniformly distributed in the entire upper layer of the HC layer is considered. The optical film can further increase the refractive index difference between the low refractive index layer and the refractive index inclined HC layer.

The optical films of Examples 1 to 9 and Comparative Examples 1 to 8 were evaluated as good for interference fringes.

However, by sequentially coating the optical films of Comparative Examples 9 and 10 in which the upper and lower HC layers were individually formed, a layer interface was generated, and interference fringes occurred.

The optical films of Examples 1 to 9 were evaluated as good in adhesion and surface.

However, the optical films of Comparative Examples 1 to 6 were lower in adhesion than the examples, and coated on the surface. In particular, in the case of the optical films of Comparative Examples 2, 4 and 6, the viscosity of at least one of the first composition and the second composition was too high, and the coating speed was easily generated at a coating speed of 20 m/min, and the evaluation of the surface was performed. For ×. Since the state of the coated surface was poor due to the occurrence of the coating pattern, it was estimated that the optical films of Comparative Examples 2, 4, and 6 were inferior in the evaluation results of the adhesion.

The optical films of Comparative Examples 7 and 8 were evaluated for good adhesion and surface. It is presumed that it is because only the first composition 1 is used and the HC layer is formed once.

The optical films of Comparative Examples 9 and 10 were evaluated as good in the planar shape, but the adhesion was insufficient. It is presumed that the upper and lower layers are formed individually, so the adhesion of the layer interface is insufficient.

In the refractive index of the optical film of the example, in the HC layer, 90% of the high refractive index fine particles were present in the film thickness of the low refractive index layer side interface of the refractive index inclined HC layer up to 70% in terms of the cross section.

However, in the optical films of Comparative Examples 1 and 3 to 6 other than Comparative Example 2, the high refractive index fine particles were distributed up to the film thickness of 90% and 95% near the TAC substrate side interface.

In the optical films of Comparative Examples 9 and 10 which were applied one by one, the high refractive index fine particles were uniformly distributed in the entire film thickness direction of the HC layer containing the high refractive index fine particles on the upper layer side.

The viscosity of the first composition and the second composition of the examples was good in productivity (suitable coatability).

However, in Comparative Examples 1 to 6, the coating speed was not produced and the coating speed was produced. The degree is low, or even if the coating speed is slowed down, the result of the coating is produced. The optical films of Comparative Examples 7 to 10 were not simultaneously coated, and the coating properties were good because one composition was applied or the composition was applied in one form.

The optical films of Comparative Examples 7 and 9 in which the hollow cerium oxide fine particles were contained in the low refractive index layer were insufficient in alkali resistance. On the other hand, in the optical films of Examples 8 and 9 in which the low refractive index layer does not contain hollow ceria particles, the sufficient antireflection property and alkali resistance can be established in two phases.

1‧‧‧Optical film

10‧‧‧Light penetrating substrate

20‧‧‧Refractive refractive index hard coating

30‧‧‧High refractive index microparticles

40‧‧‧ plate applicator head

51, 52‧‧‧ slit

60‧‧‧First hardenable resin composition for hard coat

70‧‧‧The hard curable resin composition for the second hard coat layer

80‧‧‧Low refractive index layer

90‧‧‧High refractive index microparticles

100‧‧‧Antistatic layer

Fig. 1 (a) and (b) are diagrams schematically showing an example of a method for producing an optical film of the present invention.

Fig. 2 is a schematic view showing an example of a simultaneous coating method using an extrusion type plate applicator.

Fig. 3 is a cross-sectional view schematically showing an example of a layer configuration of an optical film of the present invention and a distribution of high refractive index fine particles in a film thickness direction in a refractive index gradient HC layer.

Fig. 4 is a cross-sectional view schematically showing another example of the layer constitution of the optical film of the present invention. However, the existence of particles is omitted.

Fig. 5 is a cross-sectional view schematically showing another example of the layer constitution of the optical film of the present invention. However, the existence of particles is omitted.

Fig. 6 is a cross-sectional view schematically showing another example of the layer constitution of the optical film of the present invention. However, the existence of particles is omitted.

1. . . Optical film

10. . . Light penetrating substrate

20. . . Refractive index tilted hard coat

30. . . High refractive index microparticles

Claims (16)

A method for producing an optical film, comprising: (i) preparing a triacetyl cellulose substrate as a light penetrating substrate; (ii) preparing a first hard coat resin composition and a first a step of a curable resin composition for a second hard coat layer; the first hard coat layer curable resin composition comprising a first binder component and a first solvent, and no high refractive index microparticles, relative to the first solvent The total mass, the ratio of methyl ethyl ketone is 50% by mass or more, and the viscosity is 5 to 30 mPa s; the curable resin composition for the second hard coat layer contains a high refractive index of an average particle diameter of 1 to 100 nm. The microparticles, the second binder component, and the second solvent have a ratio of methyl ethyl ketone of 50% by mass or more, a viscosity of 10 to 50 mPa ‧ s, and a viscosity greater than the first hardness of the second solvent. a curable resin composition for coating; (iii) a curable resin composition for the first hard coat layer and the first surface side of the light transmissive substrate from the side of the light transmissive substrate The second hard coat layer is adjacent to the hard curable resin composition to the first hard coat layer a step of coating the curable resin composition on the side of the light-transmitting substrate more than the curable resin composition for the second hard coat layer to form a coating film; and (iv) the step (iii) above The obtained coating film is subjected to light irradiation to be hardened to form a step of slanting the hard coat layer. The method for producing an optical film according to claim 1, wherein the first hard coat layer curable resin composition and/or the second hard coat layer are hard. The chemical resin composition further contains a tackifier. The method for producing an optical film according to the first aspect of the invention, wherein the viscosity of the curable resin composition for the first hard coat layer and the viscosity of the curable resin composition for the second hard coat layer (mPa ‧ s) The absolute value of the difference is 30 or less. The method for producing an optical film according to the first aspect of the invention, wherein after the step (iv), further comprising (v) forming a low or high dielectric layer on the refractive index inclined hard coat layer The step of the refractive index layer. The method for producing an optical film according to the fourth aspect of the invention, wherein the low refractive index layer composition for curing the low refractive index layer contains hollow cerium oxide fine particles. The method for producing an optical film according to the fourth aspect of the invention, wherein the composition for a low refractive index layer which is formed by curing the low refractive index layer contains at least one selected from the group consisting of a metal fluoride and a curable fluororesin. One type of low refractive index material. The method for producing an optical film according to the sixth aspect of the invention, wherein the low refractive index layer composition for curing the low refractive index layer is free of hollow ceria particles and contains metal fluoride and hardenability. At least one low refractive index material selected from the group consisting of fluororesins. The method for producing an optical film according to the first aspect of the invention, wherein the step (i) and the step (iii) further comprises (vi) setting a refractive index oblique hard coating on the light penetrating substrate. Step of forming the antistatic layer on the surface of the layer Step. A method for producing an optical film, comprising: (i) a step of preparing a light-transmitting substrate; (ii) preparing a curable resin composition for a first hard coat layer and a curable resin for a second hard coat layer a step of constituting the first hard coat layer containing the first adhesive component and the first solvent, containing no high refractive index fine particles, and having a viscosity of 3 to 100 mPa·s; the second hard coat The layer hardenable resin composition contains high refractive index fine particles having an average particle diameter of 1 to 100 nm, a second adhesive component and a second solvent, and has a viscosity of 10 to 100 mPa·s; (iii) the light penetrating base. On the one side of the material, the curable resin composition for the first hard coat layer and the curable resin composition for the second hard coat layer are adjacent to each other on the side of the light-transmitting substrate, and the first hard coat is applied The layer hardening resin composition is coated on the side of the light-transmitting substrate more than the curable resin composition for the second hard coat layer to form a coating film; (iv) the above (iii) The coating film obtained in the step is subjected to light irradiation to be hardened to form a refractive index oblique hard coat layer. And (v) directly or intervening the high refractive index layer on the above-mentioned refractive index inclined hard coat layer obtained in the above step (iv), coating the hollow cerium oxide-free fine particles and containing the metal fluoride and hardening A step of forming a low refractive index layer by using a composition for a low refractive index layer of at least one of the low refractive index materials selected from the group consisting of fluororesins. The method for producing an optical film according to claim 9 of the patent application, wherein The curable resin composition for the first hard coat layer and/or the curable resin composition for the second hard coat layer further contains a tackifier. The method for producing an optical film according to the ninth aspect of the invention, wherein the viscosity of the curable resin composition for the first hard coat layer and the curable resin composition for the second hard coat layer (mPa ‧ s) The absolute value of the difference is 30 or less. The method for producing an optical film according to claim 9, wherein the light-transmitting substrate is a triacetyl cellulose substrate, and the first solvent has a permeability to the triacetyl cellulose substrate. The method for producing an optical film according to claim 9, wherein, between the steps (i) and (iii), further comprising (vi) setting a refractive index oblique hard coating on the light-transmitting substrate; The surface of the layer forms the step of forming an antistatic layer. An optical film obtained by the method according to any one of claims 1 to 13. A polarizing plate characterized in that the optical film of the above-mentioned Patent Application No. 14 is disposed on one surface side of the polarizing element with the light-transmitting substrate side of the optical film facing the polarizing element. An image display device characterized by having an optical film of claim 14 of the patent application.