JP2011133862A - Method for producing optical film, optical film, polarizing plate and display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an optical film which has high productivity, suppresses occurrence of interference fringes between a hard coat layer and a layer being in contact with a base material side of the hard coat layer and has good visibility. <P>SOLUTION: The method for producing the optical film includes: a step for preparing a light-transmissive base material; a step for preparing a first composition, which contains a first resin and a first solvent but contains no or 5.0 mass% or less, relative to mass of the first resin, of a low-refractive index component and has viscosity (μ1) of 3 mPa s or above, and a second composition, which includes the low-refractive index component, a second resin and a second solvent and has viscosity (μ2) of 5 mPa s or above and difference between μ2 and μ1 is not more than 30 mPa s; a step for simultaneously applying at least the first composition and the second composition to one face of the light-transmissive base material, the first and second compositions being adjacent each other from the base material side, to form a coating film; and a step for drying the coating film and then curing the same by light irradiation or heating without precuring the coating film prior to drying. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical film installed on the front surface of a display (image display device) such as a liquid crystal display (LCD), a cathode ray tube display (CRT), or a plasma display (PDP), a manufacturing method thereof, and the same. The present invention relates to a polarizing plate and a display.

  In the display as described above, in order to increase the visibility of the display surface, it is required that the reflection of light irradiated from an external light source such as a fluorescent lamp or sunlight is small. As a method for suppressing reflection of external light, a method using an antireflection film in which a low refractive index layer is provided on the outermost surface of a functional layer such as a hard coat layer is known (for example, Patent Document 1).

  However, as in the invention of Patent Document 1, a functional layer forming composition is applied, semi-cured with ionizing radiation to form a functional layer, and a low refractive index layer forming composition on the semi-cured functional layer. Productivity is achieved by applying multiple coating processes and curing processes in the conventional method (half-cure system) that coats and completely cures, and the sequential multi-layer coating system in which the composition is applied to each layer and cured completely. Is not good.

  On the other hand, in Patent Document 2, two or more functional layers can be applied simultaneously, resulting in high productivity, high adhesion between layers, and hindering functional separation between layers. With the intention of providing a method for producing an optical film free from the above, an A-layer and a B-layer each containing an ionizing radiation-curable resin are applied simultaneously and subjected to a first ionizing radiation irradiation (precure), and then It proposes a method for producing an optical film which is dried and cured (completely cured) by second ionizing radiation irradiation.

  However, in addition to the high adhesion between the layers coated with multiple layers, there is also a demand for high adhesion between the layers coated with multiple layers and the layer in contact with the substrate or the substrate side. In Patent Document 2, the adhesion between the layers is high and the functions between the layers are separated, but between the simultaneously applied A layer (hard coat layer or antiglare layer) and B layer (refractive index control layer). There was a layer interface.

  Further, in Patent Document 1, low refractive index fine particles such as hollow particles are included for the purpose of reducing the refractive index of the low refractive index layer. The refractive index of the low refractive index layer is reduced when it is contained in the low refractive index layer, but the functional layer in contact with the substrate side of the low refractive index layer has a higher refractive index than the low refractive index layer. There is a difference in refractive index between the low refractive index fine particles of the low refractive index layer and the functional layer at the boundary (interface), and interference fringes will occur unless precise film thickness control is performed. Display on a display using an antireflection film There was a problem that the visibility of a surface fell.

JP 2009-053691 A JP 2008-250267 A

The present invention has been made to solve the above problems, and a first object of the present invention is to provide an antireflection function by simultaneous application (multilayer application), haze, and total light transmittance. In addition, while maintaining a flat surface without streaks, the productivity is improved by reducing the coating and curing processes, and the generation of interference fringes between layers is suppressed by eliminating the interface between layers by sequential coating, and adhesion In the vicinity of the base material, by suppressing the occurrence of interference fringes between the hard coat layer and the base material by increasing the ratio of the hard coat composition having the same refractive index as that of the base material, Moreover, it is providing the optical film excellent in adhesiveness, and its manufacturing method.
The second object of the present invention is to provide a polarizing plate comprising the optical film.
The third object of the present invention is to provide a display having the optical film.

  As a result of intensive studies by the present inventors, the low refractive index fine particles and the low refractive index resin are not included, or even if the low refractive index resin is included, the mass of the curable resin including the photocurable resin and the thermosetting resin is reduced. The first composition having a specific viscosity of less than 5% by mass and the second composition containing the low refractive index fine particles and having the specific viscosity are arranged from the substrate side to the first composition. The product and the second composition are adjacently applied on the base material or a layer provided on the base material, dried without pre-cure before drying, and then cured by light irradiation or heating. Therefore, in the film thickness direction of the HC layer, there are more low refractive index fine particles on the interface side opposite to the base material of the HC layer than on the base material side, and the lower refractive index fine particles are present on the base material side. Less distribution, that is, low refractive index from the interface side opposite the substrate to the substrate side The distribution of particles gradually decreases, and a clear layer interface is formed as in the case where the conventional low refractive index layer and HC layer are formed by sequential multilayer coating or by simultaneous coating as in Patent Document 2. Not shown, also has anti-reflection function, suppresses generation of interference fringes between layers by eliminating the interface between layers by sequential coating while maintaining a haze, total light transmittance and surface shape without streaks, adhesion In the vicinity of the base material, the occurrence of interference fringes between the hard coat layer and the base material is suppressed by increasing the proportion of the hard coat composition having the same refractive index as the base material. In addition, the inventors have found that an optical film having excellent adhesion can be obtained with high productivity, and have completed the present invention.

  That is, the method for producing an optical film according to the present invention includes (i) a step of preparing a light-transmitting substrate, (ii) a first resin having reactivity and a first solvent, and low refractive index fine particles In addition, even if the low refractive index resin is not included or the low refractive index resin is included, it is 5.0% by mass or less with respect to the mass of the first resin, and the first hard coat having a viscosity μ1 of 3 mPa · s or more. Curable resin composition for layer, one or more low refractive index components selected from the group consisting of low refractive index fine particles having an average particle diameter of 10 to 300 nm and low refractive index resin, a second resin having reactivity, and a second resin A step of preparing a second curable resin composition for a hard coat layer containing two solvents, having a viscosity μ2 of 5 mPa · s or more and a value obtained by subtracting the μ1 from the μ2 of 30 mPa · s or less (iii) ) On one side of the light transmissive substrate A step of coating at least the first curable resin composition for a hard coat layer and the second curable resin composition for a hard coat layer adjacently from the light-transmitting substrate side to form a coating film, (iv ) Drying the coating film obtained in the step (iii), and then curing by light irradiation and / or heating, and between the step (iii) and the step (iv) It is characterized by not performing.

The first HC having the specific viscosity described above does not contain the low refractive index fine particles and the low refractive index resin or is less than 5.0% by mass with respect to the mass of the first resin even if the low refractive index resin is included. Including one or more low refractive index components selected from the group consisting of a low-refractive-index fine particle and a low-refractive-index resin, and a curable resin composition for layers (hereinafter sometimes referred to simply as a first composition), The second curable resin composition for the HC layer having the specific viscosity (hereinafter sometimes simply referred to as the second composition) is prepared from the light transmissive substrate side by the first composition and the second curable resin composition. By applying simultaneous multi-layer coating so that the compositions are located adjacently to form an HC layer and not performing a pre-cure, the low refractive index component contained in the second composition is in the HC layer thickness direction. There is more on the interface side opposite to the light transmissive substrate than on the light transmissive substrate side In addition, the lower refractive index component is distributed such that the amount of the low refractive index component decreases toward the light transmissive substrate side, and the low refractive index component extends from the interface opposite to the light transmissive substrate to the light transmissive substrate side. The number of interference fringes due to the difference in refractive index between the low refractive index component and the resin of the HC layer and the generation of interference fringes at the interface between the HC layer and the substrate are suppressed. An optical film excellent in visibility can be obtained.
And, since the coating film is dried without performing pre-curing, and then the film is cured by light irradiation or heating, compared with the case of curing by performing pre-curing, the HC layer and the light-transmitting substrate or HC layer Adhesion with the layer in contact with the light transmissive substrate side can be enhanced. In the present invention, the precure means light irradiation and / or heating which does not cause the coating film to be fully cured. The main curing of the coating film means that the coating film is dried, the solvent in the coating film is reduced, and the cured coating film is subjected to a pencil hardness test (4.9 N load) as defined in JIS K5600-5-4 (1999). ) Means curing that exhibits a hardness of “H” or higher.

In a preferred embodiment of the method for producing an optical film according to the present invention, in the step (iii), the wet film thickness of the first hard coat layer curable resin composition is T1, the second hard When the wet film thickness of the coating film of the curable resin composition for the coat layer is T2, a value obtained by dividing T2 by T1, that is, by setting T2 / T1 to 0.01 to 1, the film thickness of the hard coat layer In the direction, the low refractive index component is present more on the interface side opposite to the light transmissive substrate of the HC layer than the light transmissive substrate side, and the low refractive index component is present on the light transmissive substrate side. The amount of the low refractive index component is gradually reduced from the interface opposite to the light transmissive substrate to the light transmissive substrate side, and the hard coat layer is in the film thickness direction. In the interface from the opposite side to the light-transmitting substrate In the region of up to 70% of the dry thickness of the Dokoto layer, it is also possible to obtain an optical film having a distribution of 70% to 100% of the total amount of the low refractive index component is present.
Since the low refractive index component is distributed as described above, the antireflection performance of the optical film can be sufficiently exhibited even if the content of the low refractive index component is reduced.
The distribution of the low refractive index fine particles in the film thickness direction of the HC layer can be observed by a TEM (transmission electron microscope) photograph of the cross section in the film thickness direction of the HC layer.
The distribution of the low refractive index resin in the film thickness direction of the HC layer is, for example, that an optical film is embedded using a thermosetting resin, and the embedded optical film is used with an ultramicrotome manufactured by LEICA to have a thickness of 80 nm or more. It can be measured by preparing a thin section, then performing gas phase staining with RuO4 and observing with TEM.

  In a preferred embodiment of the method for producing an optical film according to the present invention, the first hard coat layer curable resin composition has a viscosity μ1 of 3 to 95 mPa · s, and the second hard coat layer curable property. It is preferable that the viscosity μ2 of the resin composition is 5 to 100 mPa · s because an HC layer having a distribution of the specific low refractive index component can be easily obtained.

  The optical film which concerns on this invention is an optical film obtained by the manufacturing method of the said optical film.

In a preferred embodiment of the optical film according to the present invention, the optical film is provided with a hard coat layer on one side of the light-transmitting substrate, and the low refractive index fine particles are formed in the film thickness direction of the hard coat layer. There is more on the interface side opposite to the light-transmitting substrate than on the light-transmitting substrate side, and the light-transmitting substrate side has less low refractive index fine particles, and the light The low refractive index component gradually decreases from the interface opposite to the transmissive substrate to the light transmissive substrate side, there is no layer interface in the hard coat layer, and the light transmission of the hard coat layer It is also possible to adjust the adhesion rate of the cross-cut adhesion test to the conductive substrate to 90 to 100%.
Here, the adhesion rate in the cross-cut adhesion test means that a 100-mm cross-cut is placed in a 1 mm square on the HC layer side surface of the optical film, and an adhesive tape having a width of 24 mm (for example, industrial product manufactured by Nichiban Co., Ltd.) This is the proportion of squares left without peeling, calculated based on the following criteria, after 5 continuous peel tests using Cellotape (registered trademark).
Adhesion rate (%) = (number of cells not peeled / total number of cells 100) × 100

  In a preferred embodiment of the optical film according to the present invention, in the film thickness direction of the hard coat layer, the region from the interface opposite to the light transmissive substrate to 70% of the dry film thickness of the hard coat layer. 70% to 100% of the total amount of the low refractive index fine particles may be present.

  The polarizing plate according to the present invention is characterized in that a polarizer is provided on the light transmissive substrate side opposite to the hard coat layer of any one of the above optical films.

  The display according to the present invention is characterized in that a display panel is disposed on the light transmissive substrate side opposite to the hard coat layer of any one of the above optical films.

  The low-refractive-index fine particles and the low-refractive-index resin are not included, or the low-refractive-index resin is included in the specific amount and the specific composition, and the low-refractive index fine particles and / or the low-refractive index. The second composition containing a specific resin and having the above specific viscosity is simultaneously applied from the light-transmitting substrate side so that the first composition and the second composition are adjacent to each other, and the precure is applied. The coating film is dried without performing light irradiation and heating to form an HC layer, so that the low refractive index fine particles and / or the low refractive index resin contained in the second composition is a film of the HC layer. In the thickness direction, the HC layer is distributed so that there is more on the interface side opposite to the light transmissive substrate than the light transmissive substrate side, and the abundance is smaller on the light transmissive substrate side. And from the interface opposite to the light transmissive substrate to the light transmissive substrate side Productivity is improved by reducing the coating process and curing process while maintaining a surface shape that has an antireflection function and has no haze, total light transmittance, and streaks, and is distributed so that the refractive index component gradually decreases. In addition, by eliminating the interface between layers by sequential coating, the generation of interference fringes between layers is suppressed, the adhesion is improved, and the hard coat composition having a refractive index similar to the refractive index of the substrate in the vicinity of the substrate By increasing the proportion of the product, the generation of interference fringes between the hard coat layer and the substrate can be suppressed, and an optical film excellent in adhesion can be obtained.

It is the cross-sectional schematic diagram which showed an example of distribution of the low refractive index microparticles | fine-particles in HC layer of the optical film obtained by the manufacturing method of this invention. It is the cross-sectional schematic diagram which showed an example of distribution of the low refractive index microparticles | fine-particles in the low-refractive-index layer of the antireflection film obtained by the conventional sequential multilayer coating system. It is the schematic diagram which showed an example of the process of apply | coating the curable resin composition for 1st and 2nd HC layers simultaneously in the manufacturing method of the optical film which concerns on this invention. It is the schematic diagram which showed an example of the laminated constitution of the 2nd optical film of this invention. It is the schematic diagram which showed another example of the layer structure of the 2nd optical film of this invention. It is the schematic diagram which showed an example of the laminated constitution of the polarizing plate of this invention. 2 is a cross-sectional view of the optical film of Example 1. FIG. 2 is an enlarged cross-sectional view of an interface portion on the opposite side of a light-transmitting substrate of a hard coat layer of an optical film of Example 1. FIG. It is sectional drawing of the optical film of the comparative example 3.

  Hereinafter, the manufacturing method of the optical film according to the present invention will be described first, and then the optical film will be described.

In the present invention, (meth) acrylate represents acrylate and / or methacrylate.
The light of the present invention includes not only electromagnetic waves having wavelengths in the visible and non-visible regions, but also particle beams such as electron beams, and radiation or ionizing radiation that collectively refers to electromagnetic waves and particle beams.
In the present invention, unless otherwise specified, the film thickness means the film thickness during drying (dry film thickness).
In the present invention, the “hard coat layer” refers to a layer having a hardness of “H” or higher in a pencil hardness test (4.9 N load) defined in JIS K5600-5-4 (1999).
In the definition of film and sheet in JIS-K6900, a sheet is a thin and generally flat product whose thickness is small relative to the length and width. A film has a thickness compared to the length and width. A thin, flat product that is extremely small and has an arbitrarily limited maximum thickness, usually supplied in the form of a roll. Accordingly, it can be said that a sheet having a particularly thin thickness is a film, but the boundary between the sheet and the film is not clear and is difficult to distinguish clearly. Therefore, in the present invention, both a thick sheet and a thin sheet are used. Including meaning, it is defined as “film”.
In the present invention, the resin is a concept including a polymer in addition to a monomer and an oligomer, and means a component that becomes a matrix of the HC layer and other functional layers after curing.
In the present invention, the molecular weight means a weight average molecular weight which is a polystyrene equivalent value measured by gel permeation chromatography (GPC) in a THF solvent when having a molecular weight distribution, and when having no molecular weight distribution, It means the molecular weight of the compound itself.
In the present invention, the average particle size of the low refractive index fine particles is a particle size including a primary particle size and a secondary particle size obtained by measuring particles in a solution by a dynamic light scattering method in the case of fine particles in a composition. This means a 50% particle diameter (d50 median diameter) when the distribution is expressed as a cumulative distribution, and can be measured using a Microtrac particle size analyzer manufactured by Nikkiso Co., Ltd. In the case of fine particles in the HC layer, it means an average value of 20 particles observed by a TEM photograph of a cross section of the HC layer.

(Optical film manufacturing method)
The method for producing an optical film according to the present invention includes (i) a step of preparing a light-transmitting substrate, (ii) a first resin having reactivity and a first solvent, and low refractive index fine particles and low Even if it does not contain a refractive index resin or contains a low refractive index resin, it is 5.0% by mass or less based on the mass of the first resin, and the viscosity μ1 is 3 mPa · s or more for the first hard coat layer. A curable resin composition, one or more low refractive index components selected from the group consisting of low refractive index fine particles having an average particle diameter of 10 to 300 nm and a low refractive index resin, a reactive second resin, and a second resin A step of preparing a second curable resin composition for a hard coat layer containing a solvent and having a viscosity μ2 of 5 mPa · s or more and a value obtained by subtracting the μ1 from the μ2 of 30 mPa · s, (iii) On one side of the light transmissive substrate, the light transmissive A step of coating at least the first curable resin composition for a hard coat layer and the second curable resin composition for a hard coat layer adjacent to each other from the material side to form a coating film; (iv) the above (iii) ) Drying the coating film obtained in the step, and then curing it by light irradiation and / or heating, and not performing pre-cure between the step (iii) and the step (iv) It is characterized by.

FIG. 1 is a schematic cross-sectional view showing an example of the distribution of low refractive index fine particles in the HC layer of an optical film obtained by the production method of the present invention.
The optical film 1 is provided with an HC layer 20 on one surface side of the light-transmitting substrate 10, and in the HC layer, the low refractive index fine particles 30 are formed on the interface side of the HC layer opposite to the light-transmitting substrate. A distribution in which there is a larger amount than the transparent substrate side, and the amount of the light-transmitting substrate side is smaller, that is, from the interface opposite to the light-transmitting substrate to the light-transmitting substrate side. The refractive index component has a distribution that gradually decreases.

FIG. 2 is a schematic cross-sectional view showing an example of a distribution of low refractive index fine particles in a low refractive index layer of an antireflection film according to a conventional sequential multilayer coating method.
The antireflection film 100 has an HC layer 110 and a low refractive index layer 120 provided on one side of the light transmissive substrate 10 from the light transmissive substrate side, and the low refractive index fine particles 30 are uniform in the low refractive index layer. However, since the low refractive index layer is formed after the HC layer is completely cured, the low refractive index fine particles are not in the HC layer, but at the interface between the low refractive index layer and the HC layer. The difference in refractive index was large, causing interference fringes. Also, the interface between the HC layer and the low refractive index layer can be clearly distinguished. Further, when a low refractive index layer having a thickness approximately equal to the thickness of the region where the low refractive index fine particles in FIG. 1 are present is formed with a conventional antireflection film, interference fringes are generated.
Thus, in the conventional sequential multi-layer coating method, when an upper layer (low refractive index layer) having a thickness similar to the thickness in which the low refractive index fine particles obtained by the coating method of the present invention are distributed, An interface is formed between the cured portion of the resulting composition and the cured portion of the upper composition, and the difference in refractive index between the low refractive index fine particles contained in the upper composition and the resin contained in the lower composition at the interface portion. Was large and interference fringes had occurred.

On the other hand, in the method for producing an optical film according to the present invention, the low refractive index fine particles and the low refractive index resin are not included, or even if the low refractive index resin is included, 5. The first composition having a specific viscosity of 0% by mass or less, and the second composition having a low refractive index component and having the specific viscosity are separated from the light-transmitting substrate side by the first composition. By simultaneously applying the composition and the second composition so as to be adjacent to each other to form an HC layer and not performing the precuring, as shown in FIG. 1, the low refraction included in the second composition is reduced. In the film thickness direction of the HC layer, the rate component is present more at the interface side opposite to the light-transmitting substrate of the HC layer than at the light-transmitting substrate side, and the refractive index is lower at the light-transmitting substrate side. Distribution where the abundance of fine particles decreases, that is, from the interface side opposite to the light-transmitting substrate The distribution is such that the low refractive index component gradually decreases toward the transmissive substrate side, and interference fringes are generated in the HC layer due to the refractive index difference between the low refractive index component and the resin of the HC layer. Generation of interference fringes at the interface with the material is suppressed, and an optical film having excellent visibility and excellent adhesion between the HC layer and the light-transmitting substrate or the layer in contact with the light-transmitting substrate is obtained.
Moreover, since it is not necessary to perform pre-cure, it is excellent in productivity compared with the case where it cures by irradiating light twice with pre-cure and main curing.

When an HC layer containing low refractive index fine particles as a low refractive index component is formed on the light transmissive substrate by simultaneous application, the reason why the adhesion between the HC layer and the light transmissive substrate is good is clear. The following reasons are presumed. That is, when the resin contained in the first composition comes into contact with the light transmissive substrate, the resin penetrates into the light transmissive substrate, resulting in chemical and / or physical bonding. It is presumed that the adhesion with the permeable substrate is improved. On the other hand, when the low refractive index fine particles contained in the HC layer are uniformly dispersed in the HC layer without taking the distribution that the abundance decreases as the light-transmitting substrate side as described above, It is presumed that only the portion occupied by the low refractive index fine particles at the interface on the light transmissive substrate side does not cause chemical and / or physical bonding between the resin and the substrate due to the penetration of the resin, and the adhesion is not increased. The
In addition, if precure is performed immediately after the first composition and the second composition are simultaneously applied on the light-transmitting substrate, polymerization or crosslinking occurs before the resin penetrates the light-transmitting substrate in the presence of a solvent. Is initiated, the molecular weight of the resin increases, the resin does not penetrate into the light-transmitting substrate, and it is presumed that the adhesion does not increase even if light irradiation or heating is performed after drying.
From these, when the HC layer of the present invention having the above-mentioned distribution of the specific low refractive index fine particles is formed by simultaneously coating the first composition and the second composition on the light transmissive substrate. Is presumed to have excellent adhesion to a light-transmitting substrate.

FIG. 3 is a schematic view showing an example of a process for simultaneously applying the first and second curable resin compositions for the HC layer in the method for producing an optical film according to the present invention.
Light transmission of the first hard coat layer curable resin composition 60 and the second hard coat layer curable resin composition 70 from the slits 51 and 52 of the die coater head 40 onto the light transmissive substrate 10, respectively. The first curable resin composition for the hard coat layer is adjacently coated so that the first curable resin composition for the hard coat layer is located on the side of the porous substrate, and the coating film 61 and the second curable resin composition for the first hard coat layer are applied. Let it be the coating film 71 of the curable resin composition for hard coat layers. In FIG. 3, the first curable resin composition for hard coat layer and the second curable resin composition for hard coat layer are originally integrated to form a hard coat layer. Therefore, the two kinds of compositions and the coating film thereof are described in different colors.

  Hereinafter, the light transmissive substrate, the first composition, and the second composition prepared in the steps (i) and (ii) will be described.

(Light transmissive substrate)
The light transmissive substrate of the present invention is not particularly limited as long as it satisfies the physical properties that can be used as the light transmissive substrate of the optical film, and is used for conventionally known hard coat films and optical films. Triacetyl cellulose, polyethylene terephthalate, cycloolefin polymer, or the like can be appropriately selected and used.
The average 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 light transmittance uses the value measured in room temperature and air | atmosphere using the ultraviolet visible spectrophotometer (For example, Shimadzu Corporation UV-3100PC).
Further, the light-transmitting substrate may be subjected to a surface treatment such as a saponification treatment or a primer layer. Further, an additive such as an antistatic agent may be added to the light transmissive substrate.
The thickness of the light-transmitting substrate is not particularly limited, and is usually about 20 μm to 300 μm, preferably 40 μm to 200 μm.

(First curable resin composition for hard coat layer)
The first curable resin composition for a hard coat layer contains a reactive first resin and a first solvent, and does not contain low refractive index fine particles and low refractive index resin or contains a low refractive index resin. However, it is 5.0 mass% or less with respect to the mass of the said 1st resin, and viscosity (mu) 1 is 5 mPa * s or more.
Even if the first composition does not contain the low refractive index fine particles and the low refractive index resin or does not contain the low refractive index resin, it is 5.0% by mass or less with respect to the mass of the first resin, The second composition described below contains a low refractive index component, has a specific viscosity, and the first composition is located closer to the light transmissive substrate than the second composition. As described above, when the two types of compositions are adjacently applied simultaneously to form the HC layer by curing the first composition and the second composition, in the film thickness direction of the HC layer, A distribution in which the low refractive index component gradually decreases from the interface side opposite to the light transmissive substrate to the light transmissive substrate side is shown in FIG. 1 when the low refractive index component is a low refractive index fine particle. As shown, low refractive index fine particles are distributed.
The viscosity μ1 of the first composition is 3 mPa · s or more and preferably 10 mPa · s or more from the viewpoint of appropriately suppressing mixing with the second composition described later. The viscosity μ1 is preferably 95 mPa · s or less, more preferably 50 mPa · s or less, and particularly preferably 30 mPa · s or less from the viewpoint of improving the coatability. The value obtained by subtracting μ1 from the viscosity μ2 of the second composition (hereinafter sometimes simply referred to as “viscosity difference”) is 30 mPa · s or less. The difference in viscosity is preferably 15 mPa · s or less, more preferably 10 mPa · s or less, from the viewpoint of suppression of mixing and the surface shape formed. In addition, the viscosity μ1 of the first composition and the viscosity μ2 of the second composition are preferably larger than μ1 from the viewpoint of coatability.
The viscosity of the first composition and the second composition to be described later is, for example, the product name MCR301 manufactured by Anton Paar, the measurement jig is PP50, the measurement temperature is 25 ° C., and the shear rate is 10,000. Under the condition of [1 / s], an appropriate amount of the composition to be measured can be dropped on the stage and measured.

  The first composition does not contain the low refractive index fine particles and the low refractive index resin or is 5.0% by mass or less based on the mass of the first resin even when the low refractive index resin is contained. Such a low refractive index component is preferably present only at the interface on the side opposite to the light-transmitting substrate of the HC layer and in the vicinity thereof from the viewpoint of developing antireflection performance. If the low refractive index component is uniformly present throughout the HC layer, the antireflection performance of the optical film may not be sufficiently exhibited, and the hardness of the HC layer may not be sufficiently exhibited. In this regard, the second composition described later has a function of distributing a large amount of the low refractive index component in the interface and the vicinity thereof. Even if the low refractive index resin is contained in the first composition, sufficient antireflection performance can be obtained in the optical film as long as the amount is as described above. The amount of the low refractive index resin contained in the first composition is preferably 1% by mass or less with respect to the mass of the first resin.

(First resin)
The first resin is a component that is reactive and hardens to become a matrix of the HC layer. The first resin has polymerization or crosslinking reactivity with the first resins and the second resin described later by light irradiation or heating. The first resin may be a photocurable resin that is cured by irradiation with light such as ultraviolet rays, or may be a thermosetting resin that is cured by heating.
When the first resin is a photocurable resin, the first resin preferably has a polymerizable unsaturated group, and more preferably has an ionizing radiation curable unsaturated group. Specific examples thereof include ethylenically unsaturated bonds such as (meth) acryloyl group, vinyl group and allyl group, and epoxy group.
When the first resin is a thermosetting resin, examples of the first resin include those having a hydroxyl group, a carboxyl group, an amino group, an epoxy group, a glycidyl group, an isocyanate group, and an alkoxyl group.
The first resin preferably has two or more reactive groups in one molecule, more preferably three or more, from the viewpoint of increasing the hardness of the HC layer by a crosslinking reaction.

  The first resin as the photocurable resin may be a conventionally known photocurable resin that becomes a matrix of the HC layer, such as pentaerythritol triacrylate (PETA) and dipentaerythritol hexaacrylate (DPHA). A polyfunctional monomer is preferably used.

  As the first resin as the thermosetting resin, for example, a compound having an epoxy group and a binder epoxy compound described in JP-A-2006-106503 can be used. Moreover, the thermosetting resin described in JP 2008-150441 A can be used.

From the viewpoint of easily adjusting the viscosity μ1 of the first composition, the molecular weight of the first resin is preferably 500 or more, and more preferably greater than 1000. From the viewpoint of easily adjusting the viscosity μ1 of the first composition, the upper limit of the molecular weight of the first resin is preferably 150,000 or less, more preferably 50000 or less, and preferably 20000 or less. Particularly preferred. When the molecular weight of the first resin is within this range, the low refractive index fine particles and the low refractive index resin contained in the second composition described later are prevented from uniformly diffusing throughout the HC layer, and the light of the HC layer is reduced. Many are likely to be present on the interface side opposite to the permeable substrate.
Examples of the resin having a molecular weight larger than 1000 include polyalkylene oxide chain-containing polymer D described in Patent Document 1, trade name beam set DK1 manufactured by Arakawa Chemical Co., Ltd., and UV curing manufactured by Shin-Nakamura Chemical Co., Ltd. Preferred examples include trade name NH oligo U-15HA, which is a type urethane acrylate oligomer, and trade name UV-1700B manufactured by Nippon Synthetic Chemical Industry Co., Ltd.

From the viewpoint of suppressing the occurrence of interference fringes at the interface between the HC layer and the substrate, it is preferable that the first resin contains a resin having a molecular weight of 1000 or less. As such a resin having a molecular weight of 1000 or less, the above PETA and DPHA are preferably mentioned.
As the first resin, when a resin having a molecular weight of 1000 or less and another resin, that is, a resin having a molecular weight of greater than 1000 are used in combination, the content of the resin having a molecular weight of 1000 or less depends on the desired viscosity or the like. What is necessary is just to adjust suitably, but it is preferable that content of resin with a molecular weight of 1000 or less is 50-100 mass% with respect to the total mass of 1st resin.

  Further, from the viewpoint of the hardness of the HC layer, the molecular weight of the first resin is preferably 5000 or less.

  In addition, as the first resin, for example, the binder C described in Patent Document 1 may be used. As a commercial product of the binder C, trade name AH-600 manufactured by Kyoeisha Chemical Co., Ltd., which is a commercial product of urethane acrylate having a weight average molecular weight of less than 10,000 and having two or more polymerizable unsaturated groups. , AT-600, UA-306H, UA-306T, UA-306I, etc., trade names UV-3000B, UV-3200B, UV-6300B, UV-6330B, UV-7000B, etc. manufactured by Nippon Synthetic Chemical Industry Co., Ltd. Trade name beam set 500 series (502H, 504H, 550B, etc.) manufactured by Arakawa Chemical Industries, Ltd., trade names U-6HA, UA-32P, U-324A manufactured by Shin-Nakamura Chemical Co., Ltd., Toagosei Co., Ltd. ) Manufactured product name M-9050 and the like.

What is necessary is just to adjust suitably and use content of 1st resin, 40-90 mass% is preferable with respect to the total solid of a 1st composition, More preferably, it is 50-80 mass%.
1st resin may be used individually by 1 type, and may be used in combination of 2 or more type. Further, the first resin may be the same as or different from the second resin contained in the second composition to be described later, the basic skeleton, the type of functional group, the number of functional groups, or the molecular weight.

(First solvent)
The first solvent has a function of adjusting the viscosity by dissolving or dispersing solid components such as the first resin in the first composition.
As a 1st solvent, 1 type (s) or 2 or more types can be used from the solvent currently used for the composition for a conventionally well-known hard-coat layer. For example, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), toluene and the like, alcohols, ketones, esters, halogenated hydrocarbons, aromatic hydrocarbons, ethers described in JP-A-2005-316428 Etc. As the first solvent, for example, ethers such as tetrahydrofuran, 1,4-dioxane, dioxolane and diisopropyl ether and glycols such as methyl glycol, propylene glycol monomethyl ether (PGME) and methyl glycol acetate are used. be able to.
From the viewpoint of adjusting (enhancing) the viscosity of the first composition, the first solvent preferably has a high viscosity, preferably 1 mP · s or more, and more preferably 2 mP · s or more. As a solvent for increasing the viscosity of the first composition, for example, propylene glycol monomethyl ether (PGME) is preferable.
In addition, by appropriately selecting the type of the first solvent and the type of the light transmissive substrate, the first solvent also functions to permeate a part of the first resin into the light transmissive substrate. Have.
In the present invention, it is easy to suppress the occurrence of interference fringes when the first resin penetrates the substrate by using (or using in combination) a solvent (permeable solvent) that is permeable to the light transmissive substrate, Adhesion can also be improved.
In the present invention, penetrability means not only the property of penetrating the light transmissive substrate but also the concept of swelling or wetting the light transmissive substrate.
Specific examples of the permeable solvent include ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as methyl acetate, ethyl acetate and butyl acetate, halogenated hydrocarbons and phenols.
Examples of the solvent used when the light-transmitting substrate is triacetyl cellulose (TAC) and the solvent used when the light-transmitting substrate is polyethylene terephthalate (PET) include the solvents described in JP-A-2005-316428. It is done.
In particular, methyl acetate, ethyl acetate, butyl acetate and methyl ethyl ketone are preferable as the solvent used when the light-transmitting substrate is triacetyl cellulose (TAC).
The first solvent may be the same as or different from the second solvent contained in the second composition described below.

  In the first composition, the ratio of the mass of the first resin to the mass of the first solvent is 100 to 400% by mass, and the low refractive index component on the side opposite to the light-transmitting substrate in the HC layer Is preferable from the viewpoint of distributing a large amount of. At this time, in the second composition described later, the ratio of the total mass of the low refractive index component and the second resin to the mass of the second solvent is 100 to 400% by mass.

(Other components of the curable resin composition for the first hard coat layer)
In addition to the above components, the first composition may further contain a polymerization initiator, an antistatic agent, a thickener, a reactive or non-reactive leveling agent, etc. for the purpose of imparting functionality. .

(Polymerization initiator)
If necessary, radicals and cationic polymerization initiators may be appropriately selected and used. These polymerization initiators are decomposed by light irradiation and / or heating to generate radicals or cations to advance radical polymerization and cationic polymerization. For example, as a radical polymerization initiator, Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone) manufactured by Ciba Japan Co., Ltd. may be mentioned.
When using a photocationically polymerizable first resin such as a first resin containing an epoxy group, for example, a cationic polymerization initiator described in JP 2010-107823 A may be used as necessary. it can.
When using a polymerization initiator, the content is preferably 1 to 10% by mass relative to the total solid content of the first composition.

(Antistatic agent)
As the antistatic agent, a conventionally known antistatic agent can be used. For example, a cationic antistatic agent such as a quaternary ammonium salt described in JP-A-2007-264221, or tin-doped indium oxide (ITO). Fine particles such as these can be used.
When using an antistatic agent, it is preferable to use the content by 30-60 mass% with respect to the total solid of a 1st composition.

(Thickener)
The first composition may contain a thickener for the purpose of adjusting the viscosity.
As the thickener, conventionally known thickeners can be used, for example, protein systems such as casein and salt of casein, polyvinyl alcohol, aliphatic amide, acrylic copolymer, polyvinylpyrrolidone, sodium polyacrylate, etc. And organic thickeners such as polyether dialkyl ester, partial ester of vinyl methyl ether-maleic anhydride copolymer, and acetylene glycol. In addition, inorganic thickeners such as microsilica, kaolin bentonite and talc are also included.
The above organic thickener and inorganic thickener may be used alone or in combination of two or more.
When using a thickener, it is preferable to use the content by 0.1-10 mass% with respect to the total solid of a 1st composition.

(Leveling agent)
The leveling agent has a function of imparting coating stability, slipperiness, antifouling property or scratch resistance to the HC surface.
As the leveling agent, there can be used fluorine-based, silicone-based, acrylic-based leveling agents and the like used in conventionally known antireflection films. For example, a fluorine-based leveling agent having no ionizing radiation curable group such as Megafic series (MCF350-5) manufactured by DIC Corporation, or an ionizing radiation curable group such as X22-163A manufactured by Shin-Etsu Chemical Co., Ltd. Any of the silicone leveling agents can be used.
As content when using a leveling agent, in the case of a fluorine-type leveling agent, it is 5.0 mass% or less with respect to the mass of 1st resin, and it is used by 0.1-3.0 mass%. In the case of a leveling agent other than fluorine-based, it is preferably used at 0.5 to 10% by mass with respect to the mass of the first resin.
Further, from the viewpoint of the hardness of the HC layer, the content of the leveling agent is preferably 5.0% by mass or less with respect to the total mass of the solid content of the first composition and the second composition.

  The first composition is usually prepared by mixing and dispersing a first initiator in the first solvent and a polymerization initiator or the like contained as necessary in accordance with a general preparation method. A paint shaker or a bead mill can be used for mixing and dispersing.

(Second curable resin composition for hard coat layer)
The second curable resin composition for a hard coat layer used in the method for producing an optical film according to the present invention is one or more selected from the group consisting of low refractive index fine particles having an average particle diameter of 10 to 300 nm and a low refractive index resin. And a second resin having reactivity and a second solvent, the viscosity μ2 is 5 mPa · s or more, and the difference in viscosity is 30 mPa · s or less.
The second composition includes a low refractive index component, has the specific viscosity, and the first composition is positioned on the light-transmitting substrate side with respect to the second composition. When the first composition and the second composition are cured to form the HC layer by the simultaneous application of the compositions, the light-transmitting substrate in the film thickness direction of the HC layer When the low refractive index component is gradually reduced from the opposite interface side to the light-transmitting substrate side, and the low refractive index component is a low refractive index fine particle as shown in FIG. Low refractive index fine particles are distributed.

  The viscosity μ2 of the second composition used in the method for producing an optical film according to the present invention is 5 mPa · s or more and 10 mPa · s or more from the viewpoint of moderately suppressing mixing with the first composition. It is preferable. The viscosity μ2 is preferably 100 mPa · s or less, more preferably 50 mPa · s or less, and particularly preferably 30 mPa · s or less, from the viewpoint of improving coatability. In addition, the viscosity μ1 of the first composition and the viscosity μ2 of the second composition are preferably larger than μ1 from the viewpoint of coatability.

(Low refractive index fine particles)
The low refractive index fine particles used in the method for producing the first optical film according to the present invention are present on the interface side opposite to the light-transmitting substrate of the HC layer, so that the optical film of the present invention has antireflection properties. Is granted. In addition to the low refractive index fine particles, a low refractive index resin, which will be described later, may be used together.
Low refractive index fine particles have a refractive index of 1.20 to 1.45.
As the low-refractive fine particles, particles conventionally used in a low-refractive index layer can be used. For example, hollow silica fine particles described in Patent Document 2, LiF (refractive index 1.39), MgF ₂ Metals such as (magnesium fluoride, refractive index 1.38), AlF ₃ (refractive index 1.38), Na ₃ AlF ₆ (cryolite, refractive index 1.33) and NaMgF ₃ (refractive index 1.36) Examples include fluoride fine particles.
Moreover, the surface of the low refractive index fine particles may be coated with an organic component having a polymerizable unsaturated group or a thermosetting group so that the surface thereof can be cross-linked with the second resin or the first resin. As a coating method, a method for preparing reactive inorganic fine particles described in JP-A-2008-165040 can be used.
The average particle diameter of the low refractive index fine particles is 300 nm or less from the viewpoint of preventing the haze increase of the HC layer. In the case where the low refractive index fine particles are hollow silica fine particles, the average particle diameter is 10 nm or more from the viewpoint of expressing the effect of lowering the refractive index because voids are required.
The average particle diameter of the low refractive index fine particles is preferably 10 to 100 nm, more preferably 30 to 100 nm.
The content of the low refractive index fine particles may be appropriately adjusted and used, and is preferably 50 to 90% by mass, more preferably 65 to 90% by mass with respect to the total mass with the second resin contained in the second composition. 90% by mass.

(Low refractive index resin)
The low refractive index resin refers to a resin having a refractive index of 1.30 to 1.45 after the coating film is formed. In addition to the low refractive index resin, the low refractive index fine particles may be used together.
Further, since the low refractive index resin is a component that can become a part of the matrix of the HC layer after the coating film is formed, the low refractive index resin may be used also as the second resin described later.
As the low refractive index resin, a conventionally known fluorine-containing resin having a reactive group such as a photocurable group or a thermosetting group, a fluorine-containing resin having no reactive group, or the like can be used.

Examples of the fluorine-containing resin having a photocurable group include fluoroolefins such as vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluorobutadiene, perfluoro-2,2-dimethyl-1,3-dioxole. Can be mentioned.
Other fluorine-containing resins having a photocurable group include 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3,3-pentafluoropropyl (meth) acrylate 2- (perfluoro Butyl) ethyl (meth) acrylate, 2- (perfluorohexyl) ethyl (meth) acrylate, 2- (perfluorooctyl) ethyl (meth) acrylate, 2- (perfluorodecyl) ethyl (meth) acrylate, α-tri (Meth) acrylate compounds such as methyl fluoromethacrylate and ethyl α-trifluoromethacrylate, a C1-C14 fluoroalkyl group, fluorocycloalkyl group or fluoroalkylene group having at least three fluorine atoms in one molecule And having at least two (meth) acryloyloxy groups. Fluorine polyfunctional (meth) acrylic acid ester compounds and the like.

  Examples of the fluorine-containing resin having a thermosetting group include 4-fluoroethylene-perfluoroalkyl vinyl ether copolymer, fluoroethylene-hydrocarbon vinyl ether copolymer, epoxy resin, polyurethane resin, cellulose resin, phenol resin, and polyimide. Fluorine modified products such as resins can be used.

  In addition, a polymer, a copolymer, and a silicone-containing vinylidene fluoride copolymer containing a fluorine atom-containing polymerizable compound described in JP 2010-122603 A may be used.

The molecular weight of the low refractive index resin is not particularly limited and can be appropriately selected, but 500 to 5000 is preferable from the viewpoint of adjusting the viscosity of the second composition.
The content of the low refractive index resin contained in the second composition may be adjusted as appropriate, but when the low refractive index resin also serves as the second resin described later, the total solid content of the second composition On the other hand, it is preferable that it is 70-100 mass%.

(Second resin)
The second resin is reactive and is a component that cures and becomes a matrix of the HC layer. The second resin has polymerization or crosslinking reactivity with the second resins and the first resin by light irradiation or heating.

The second resin may be a photocurable resin that is cured by irradiation with light such as ultraviolet rays, or may be a thermosetting resin that is cured by heating. When the second resin is a photocurable resin, the second resin preferably has a polymerizable unsaturated group, and more preferably has an ionizing radiation curable unsaturated group. Specific examples thereof include ethylenically unsaturated bonds such as (meth) acryloyl group, vinyl group and allyl group, and epoxy group.
When the second resin is a thermosetting resin, examples of the thermosetting group of the second resin include a hydroxyl group, a carboxyl group, an amino group, an epoxy group, a glycidyl group, an isocyanate group, and an alkoxyl group. .
The second resin preferably has two or more curable groups in one molecule, more preferably three or more, from the viewpoint of increasing the hardness of the HC layer by a crosslinking reaction.
As the second resin, those mentioned in the first resin can be used.

The content of the second resin may be appropriately adjusted and used, and is preferably 60% by mass or less with respect to the total solid content of the second composition. When the second resin also serves as a low refractive index resin, it may be 100% by mass or less based on the total solid content of the second composition.
A 2nd resin may be used individually by 1 type, and may be used in combination of 2 or more type.

(Second solvent)
In the second composition, the second solvent functions to adjust the viscosity by dissolving or dispersing solids such as the low refractive index fine particles and the second resin. As the second solvent, those mentioned in the first solvent can be used.

(Other components of the curable resin composition for the second hard coat layer)
In addition to the above components, the second composition further includes a polymerization initiator, an antistatic agent, a thickener, an antifouling agent, and a reactive or non-reactive material in the same manner as the first composition for the purpose of imparting functionality. A reactive leveling agent or the like may be contained.

(Polymerization initiator)
As the polymerization initiator, those mentioned in the first composition can be used.
When using a polymerization initiator, it is preferable to use the content by 1-5 mass% with respect to the total solid of a 2nd composition.

(Antistatic agent)
As the antistatic agent, those mentioned in the first composition can be used.
When using an antistatic agent, it is preferable that the content is 30-60 mass% with respect to the total solid of a 2nd composition.

(Thickener)
As the thickener, those mentioned in the first composition can be used.
As content of a thickener, it is preferable to use at 0.1-10 mass% with respect to the total solid of a 2nd composition.

(Anti-fouling agent)
The antifouling agent prevents the outermost surface of the optical film from being stained, and can also impart scratch resistance to the HC layer. An antifouling agent may be included in both the first composition and the second composition. From the viewpoint of efficiently expressing the antifouling property with a small content, the antifouling agent is preferably contained only in the second composition.
As the antifouling agent, a conventionally known antifouling agent (antifouling agent) such as a fluorine compound or a silicon compound may be used.
Examples of the antifouling agent include antifouling agents described in JP-A-2007-264279.
It is also preferable to use a commercially available antifouling agent. Examples of such commercially available antifouling agents (non-reactive) include Megafac series manufactured by DIC Corporation, such as trade names MCF350-5, F445, F455, F178, F470, F475, F479, F477, and TF1025. , F478 and F178K, TSF series manufactured by Toshiba Silicone Co., Ltd., X-22 series and KF series manufactured by Shin-Etsu Chemical Co., Ltd., and Silaplane series manufactured by Chisso Corporation.
As a commercially available antifouling agent (reactivity), trade name SUA1900L10 and trade name SUA1900L6 manufactured by Shin-Nakamura Chemical Co., Ltd. UT3971 manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Def Co., Ltd., Def Co., Ltd., Def Co., Ltd., Def Co., Ltd., Def Co., Ltd. Trade name KNS5300 manufactured by GE Toshiba Silicone Co., Ltd., trade names UVHC1105 and UVHC8550 manufactured by GE Toshiba Silicone, and trade name ACS-1122 manufactured by Nippon Paint Co., Ltd.

(Leveling agent)
As the leveling agent, those mentioned in the first composition can be used.
The leveling agent may be contained in either the first composition or the second composition, but from the viewpoint of efficiently expressing the function of the leveling agent, it may be contained only in the second composition. preferable.
As content when using a leveling agent, in the case of a fluorine-type leveling agent, it is 5.0 mass% or less with respect to the mass of 2nd resin, and should be used by 0.1-3.0 mass%. In the case of a leveling agent other than fluorine-based, it is preferably used at 0.5 to 10% by mass with respect to the mass of the second resin.

  As a method for preparing the second composition, the method described in the first composition can be used.

(Other functional layer compositions)
In the method for producing an optical film according to the present invention, at least the first and second compositions may be simultaneously coated on one side of the light-transmitting substrate in the step (iii) of simultaneous coating. Depending on the required performance, other functional layer compositions may be prepared to provide other functional layers as appropriate.
Examples of other functional layers include an antistatic layer and an antifouling layer.
As will be described later, other functional layer compositions can be appropriately applied according to their functions as long as they are applied adjacently so that the first and second compositions are located from the light-transmitting substrate side. The position can be set.

  (Iii) In the step of simultaneously applying the first composition and the second composition in the method for producing an optical film according to the present invention, the method of simultaneously applying the first and second compositions can be applied simultaneously. Any known method can be used as long as it is a conventional one. For example, a method using an extrusion type die coater as shown in FIG. 3 can be used.

  In the step (iii) of simultaneously applying the first composition and the second composition in the optical film production method, the wet film thickness of the coating film of the first composition is T1, and the coating of the second composition When the wet film thickness of the film is T2, T2 / T1 is set to 0.01 to 1 so that the low refractive index component is opposite to the light-transmitting substrate of the HC layer in the film thickness direction of the HC layer. There is more on the interface side than the light transmissive substrate side, and the light transmissive substrate side is distributed so that the abundance of the low refractive index component decreases, and the interface on the side opposite to the light transmissive substrate side The low refractive index component gradually decreases from the light-transmitting base material side, and the hard coat layer is dried from the interface opposite to the light-transmitting base material in the film thickness direction of the hard coat layer. 70 to 100% of the total amount of the low refractive index component exists in a region up to 70% of the film thickness. It is possible to fabric, from the viewpoint for effectively enhancing the antireflection property of the optical film. Here, the wet film thickness is the thickness of the coating film in a state before the solvent in the composition immediately after application is volatilized, and (volume of the composition applied on the light-transmitting substrate / application area). It is requested from.

  When the first and second compositions are applied using a die coater head as shown in FIG. 3, the coater gap 80, which is the distance between the die coater head 40 and the light-transmitting resin substrate 10, and light. The total thickness 90 of the coating films of the first and second compositions upon simultaneous multi-layer coating on the transparent resin substrate 10 has a relationship of coater gap 80 <(twice the thickness 90). Is preferred. By simultaneously applying multiple layers while maintaining such a relationship, a coating bead formed between the light-transmitting resin substrate 10 and the die coater head 40 is stabilized. In particular, this coating bead tends to become unstable as the layer formed by coating becomes thinner, causing unevenness on the coated surface and deteriorating the appearance, but the relationship between the coater gap 80 and the thickness 90 described above. By keeping the above, it becomes easy to stabilize the coating bead. In addition, a coating bead means the liquid pool produced | generated between a coating device and a base material.

  The other functional layer composition may be applied simultaneously with the first and second compositions, or may be applied separately from the first and second compositions. In the case of simultaneous application, the application position can be appropriately set according to the function as long as application is performed adjacently so that the first and second compositions are located from the light transmissive substrate side. For example, when the antistatic layer composition is applied simultaneously with the first and second compositions, the upstream side in the transport direction 140 of the light-transmitting substrate from the slit 51 of the die head in FIG. 3, a third slit (not shown) may be provided on the left side of the slit 51 to apply the antistatic layer composition and the first and second compositions simultaneously. For example, when the antistatic layer composition, the first and second compositions, and the antifouling layer composition are applied simultaneously, the antistatic layer composition is applied to the left side of the slit 51 in FIG. And a fourth slit (not shown) for applying the antifouling layer composition on the right side of the slit 52, and the four kinds of compositions are simultaneously used. What is necessary is just to apply.

Examples of the drying method in the step (iv) include a vacuum drying method or a heat drying method, and a method in which these drying methods are combined. Moreover, when drying at normal pressure, it is preferable to dry at 30-110 degreeC.
In the present invention, precure is not performed before the step (iv), that is, before the coating film is dried.
For example, when methyl isobutyl ketone is used as the first or second solvent, it is usually room temperature to 80 ° C., preferably 40 ° C. to 70 ° C., and 20 seconds to 3 minutes, preferably 30 seconds to 1 Drying takes about a minute.
In the present invention, the drying in the step (iv) means that the layer is not sufficiently cured as a product even if the drying is performed (for example, a pencil hardness test (specified in JIS K5600-5-4 (1999) ( 4.9 N load) and a hardness of less than “H”), the heating performed after drying when the first resin or the second resin contains a thermosetting resin It means that the treatment is performed at a temperature at which the layer is sufficiently cured by heating (hardness “H” or higher in the pencil hardness test).

As the light irradiation method in the step (iv), ultraviolet rays, visible light, electron beams, ionizing radiation, or the like is mainly used. In the case of ultraviolet curing, ultraviolet rays or the like emitted from light such as an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, or a metal halide lamp are used. The irradiation amount of the energy ray source is 50 to 300 mJ / cm ² as an integrated exposure amount at an ultraviolet wavelength of 365 nm.

In the present invention, pre-curing is not performed, and light irradiation and heating for curing (main curing) the coating film are performed after the coating film is dried. As a result, the low refractive index component contained in the second composition is present more in the thickness direction of the HC layer on the interface side of the HC layer opposite to the light transmissive substrate than on the light transmissive substrate side. In addition, the low refractive index component is distributed so that the abundance of the low refractive index component decreases toward the light transmissive substrate side, from the interface opposite to the light transmissive substrate to the light transmissive substrate side. Is gradually reduced, suppressing the generation of interference fringes due to the refractive index difference between the low refractive index component and the resin of the HC layer in the HC layer, and the generation of interference fringes at the interface between the HC layer and the substrate, Moreover, the optical film excellent in visibility is obtained.
In addition, the coating film is dried without pre-curing, and then the film is cured by light irradiation or heating. Therefore, compared with the case of curing by pre-curing, the HC layer and the light-transmitting substrate or HC layer Adhesion with the layer in contact with the light transmissive substrate side can be enhanced.
Moreover, since it is not necessary to perform pre-cure, it is excellent in productivity compared with the case where it cures by irradiating light twice with pre-cure and main curing.

(Optical film)
The optical film according to the present invention is obtained by the above manufacturing method, and as shown in FIG. 1, at least an HC layer 20 is provided on one surface side of the light transmissive substrate 10.
The optical film of the present invention is produced by the production method described above, so that the low refractive index fine particles and / or the low refractive index resin contained in the second composition is in the film thickness direction of the HC layer and the light transmittance of the HC layer. There is more on the interface side opposite to the base material than the light-transmitting base material side, and the light-transmitting base material side is distributed so that its abundance decreases, and its low refractive index in the HC layer An optical film that suppresses the generation of interference fringes due to the difference in refractive index between the fine particles and / or the low refractive index resin and the resin of the HC layer, and the generation of interference fringes at the interface between the HC layer and the substrate, and is excellent in visibility. Is obtained.
In addition, since the coating film is dried without pre-curing and then cured by light irradiation or heating, compared with the conventional case of performing pre-curing and then drying, light irradiation or heating to cure. When the refractive index layer and the HC layer are formed by sequential multilayer coating or when the refractive index layer and the HC layer are formed by simultaneous coating as in Patent Document 2, the layer interface does not show a clear layer, and has an antireflection function. Hard coat composition with a refractive index comparable to the refractive index of the base material in the vicinity of the base material while suppressing the generation of interference fringes between layers while maintaining the light transmittance and the surface shape without streaks. By increasing the proportion of the object, the generation of interference fringes between the hard coat layer and the substrate is suppressed, and the adhesiveness is excellent.

The optical film of the present invention may be coated with another functional layer composition as described in the above production method to form another functional layer. For example, the light-transmitting substrate of the first composition When an antistatic layer is formed by coating the antistatic layer composition on the side, the antistatic layer 140 and the HC layer 20 are configured from the light transmissive substrate 10 side as shown in FIG.
Moreover, as shown in FIG. 5, you may provide the antifouling layer 150 in the surface on the opposite side to the light transmissive base material of HC layer.

  The dry film thickness (hereinafter also simply referred to as “film thickness”) of the HC layer can be appropriately adjusted according to the required performance. For example, the film thickness is preferably 1 to 20 μm.

  The thickness of the other functional layer may be adjusted as appropriate. For example, the thickness of the antistatic layer is preferably 0.05 to 5 μm, and the thickness of the antifouling layer is preferably 0.01 to 10 nm.

The optical film of the present invention can adjust its reflectance by adjusting the type and content of the low refractive index fine particles and low refractive index resin of the second composition as appropriate according to the required performance. The reflectance with respect to light is preferably 1 to 3.75, and more preferably 1 to 3.4.
The reflectivity is 5 ° with an incident angle of 5 °, a polarizer using a trade name V7100 type UV-visible spectrophotometer manufactured by JASCO Corporation and a trade name VAR-7010 absolute reflectometer manufactured by JASCO Corporation. Is N-polarized light, the measurement wavelength range is 380 to 780 nm, a black tape is pasted on the TAC substrate side of the optical film, and it is installed in an apparatus and measured. In addition, let the average value of the measurement result calculated | required in the measurement wavelength range be a reflectance.

The haze of the optical film of the present invention can be appropriately adjusted according to the required performance, but is preferably 0.1 to 1.0%, more preferably 0.1 to 0.4%. preferable.
The haze value can be measured by a reflection / transmittance meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.) according to JIS K7136.

In a preferred embodiment of the optical film according to the present invention, the optical film is provided with a hard coat layer on one side of the light-transmitting substrate, and the low refractive index fine particles are formed in the film thickness direction of the hard coat layer. There is more on the interface side opposite to the light-transmitting substrate than on the light-transmitting substrate side, and the light-transmitting substrate side has less low refractive index fine particles, and the light The low refractive index component gradually decreases from the interface opposite to the transmissive substrate to the light transmissive substrate side, there is no layer interface in the hard coat layer, and the light transmission of the hard coat layer It is also possible to adjust the adhesion rate of the cross-cut adhesion test to the conductive substrate to 90 to 100%.
As shown in FIG. 1, by taking such a low refractive index fine particle distribution in the HC layer, it has an antireflection function and maintains a surface shape without haze, total light transmittance, and streaks. Suppresses the generation of interference fringes between layers, improves adhesion, and increases the ratio of the hard coat composition having a refractive index similar to the refractive index of the base material in the vicinity of the base material to increase the hard coat layer and the base material. The optical film excellent in adhesiveness is obtained by suppressing the generation of interference fringes between the two.
The layer interface in the hard coat layer means that an interface (boundary) is formed in the cured portion of the composition in the layer as shown in FIG. As a specific example of the layer interface, there is a boundary between cured portions of two kinds of compositions shown in FIG. 9 described later.

  In a preferred embodiment of the optical film according to the present invention, in the film thickness direction of the hard coat layer, the region from the interface opposite to the light transmissive substrate to 70% of the dry film thickness of the hard coat layer. 70% to 100% of the total amount of the low refractive index fine particles may be present. Thereby, the antireflective property of an optical film can be improved efficiently.

The total light transmittance (τt) of the optical film of the present invention is preferably 90% or more, more preferably 92% or more from the viewpoint of transparency.
The total light transmittance of the optical film can be measured with the same measuring device as the haze value according to JIS K7361.

(Polarizer)
The polarizing plate according to the present invention is characterized in that a polarizer is provided on the light transmissive substrate side opposite to the hard coat layer of the optical film.
FIG. 6 is a schematic diagram showing an example of the layer configuration of the polarizing plate according to the present invention. The polarizing plate 2 shown in FIG. 6 has the optical film 1 in which the HC layer 20 is provided on the light-transmitting substrate 10, and the polarizer 180 in which the protective film 160 and the polarizing layer 170 are laminated. A polarizer 180 is provided on the side of the light transmissive substrate 10 opposite to the HC layer 20 of one.

  Note that the polarizer is disposed on the side of the light-transmitting substrate opposite to the hard coat layer of the optical film, not only when the optical film and the polarizer are separately formed, but also the optical film. The case where the member to serve also serves as the member constituting the polarizer is included.

  Moreover, when using the polarizing plate which concerns on this invention for a display panel, a display panel is normally arrange | positioned at the polarizer side.

  In addition, about an optical film, since the optical film mentioned above should just be used, description here is abbreviate | omitted. Hereinafter, another configuration of the polarizing plate according to the present invention will be described.

(Polarizer)
The polarizer used in the present invention is not particularly limited as long as it has predetermined polarization characteristics, and a polarizer generally used in a liquid crystal display device can be used.
The polarizer is not particularly limited as long as it can maintain predetermined polarization characteristics for a long period of time. For example, the polarizer may be composed of only a polarizing layer, and a protective film and a polarizing layer are bonded together. There may be. When the protective film and the polarizing layer are bonded together, the protective film may be formed only on one side of the polarizing layer, or the protective film may be formed on both sides of the polarizing layer.

  As the polarizing layer, usually, a film made of polyvinyl alcohol is impregnated with iodine and uniaxially stretched to form a complex of polyvinyl alcohol and iodine.

The protective film is not particularly limited as long as it can protect the polarizing layer and has a desired light transmittance.
As the light transmittance of the protective film, the transmittance in the visible light region is preferably 80% or more, and more preferably 90% or more.
In addition, the transmittance | permeability of the said protective film can be measured by JISK7361-1 (The test method of the total light transmittance of a plastic-transparent material).

  Examples of the resin constituting the protective film include cellulose derivatives, cycloolefin resins, polymethyl methacrylate, polyvinyl alcohol, polyimide, polyarylate, and polyethylene terephthalate. Among these, it is preferable to use a cellulose derivative or a cycloolefin resin.

  The protective film may be composed of a single layer or may be a laminate of a plurality of layers. When the protective film is a laminate of a plurality of layers, a plurality of layers having the same composition may be laminated, or a plurality of layers having different compositions may be laminated.

  In addition, the thickness of the protective film allows the flexibility of the polarizing plate of the present invention to be within a desired range, and the dimensional change of the polarizer can be within a predetermined range by being bonded to the polarizing layer. Although it is not particularly limited as long as it is in the range, it is preferably in the range of 5 to 200 μm, particularly preferably in the range of 15 to 150 μm, and more preferably in the range of 30 to 100 μm. . If the thickness is less than 5 μm, the dimensional change of the polarizing plate of the present invention may increase. Moreover, when the said thickness is thicker than 200 micrometers, when cutting the polarizing plate of this invention, there exists a possibility that a process waste may increase or abrasion of a cutting blade may become quick.

  The protective film may have retardation. By using a protective film having retardation, there is an advantage that the polarizing plate of the present invention can have a viewing angle compensation function for a display panel.

  The aspect in which the protective film has retardation is not particularly limited as long as the protective film can exhibit desired retardation. As such an embodiment, for example, the protective film has a configuration consisting of a single layer, and includes an optical property developing agent that expresses retardation, and has retardation, and the above-described resin. By having a structure in which a retardation layer containing a compound having refractive index anisotropy is laminated on the protective film to be formed, an embodiment having retardation can be mentioned. In the present invention, any of these embodiments can be suitably used.

(display)
The display according to the present invention is characterized in that a display panel is arranged on the light transmissive substrate side opposite to the hard coat layer of the optical film.
Examples of the display include LCD, PDP, ELD (organic EL, inorganic EL), and CRT.
The display includes a display panel as a viewer side member of the display and a back side member including a driving unit. Taking a liquid crystal display as an example, the display panel is a member composed of two glass plates (for example, a color filter substrate and an array substrate) in which a liquid crystal material is confined, a polarizing plate, and the optical film of the present invention. When taking a liquid crystal display as an example, the back-side member is a member made up of a light source called a backlight, a drive circuit that controls the LCD, a circuit that controls the light source, a chassis, and the like. As an example of the layer structure of the liquid crystal display in this case, there is a backlight portion including a light guide plate, a diffusion film, etc., and the viewer side has a polarizing plate, an array substrate, a liquid crystal layer, a color filter substrate, a polarizing plate, an optical film. Are stacked in this order.

  A PDP, which is another example of the display, includes a front glass substrate and a rear glass substrate disposed so as to be opposed to the front glass substrate with a discharge gas sealed therebetween. When the display is a PDP, the optical film is also provided on the surface of the surface glass substrate or the front plate (glass substrate or film substrate).

  In the above display, a light emitter such as zinc sulfide or a diamine substance that emits light when a voltage is applied is vapor-deposited on a glass substrate. It may be a display such as a CRT that generates a visible image. In this case, the optical film is provided on the outermost surface of the ELD device or CRT or the surface of the front plate.

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

As low refractive index fine particles, hollow silica fine particles manufactured by JGC Catalysts & Chemicals Co., Ltd. (trade name: Sululia DAS (average particle size 50 nm, MIBK dispersion, solid content 20%)) were used.
As the first resin (1), trade name beam set DK1 (weight average molecular weight 20000, solid content 75%, MIBK solvent) manufactured by Arakawa Chemical Industries, Ltd. was used.
Pentaerythritol triacrylate manufactured by Nippon Kayaku Co., Ltd. was used as the first resin (2).
As a low-refractive index resin that also serves as the first resin, LINC-3A (triacryloyl-heptadecafluorononenyl-pentaerythritol (main component) represented by the following general formula (1) and pentane) manufactured by Kyoeisha Chemical Co., Ltd. A mixture of erythritol triacrylate) was used.

As a polymerization initiator, trade name Irgacure (Irg) 184 manufactured by Ciba Japan Co., Ltd. was used.
As a leveling agent, trade name MCF350-5 (solid content 5%) manufactured by DIC Corporation was used.
MIBK was used as a solvent.
As the light-transmitting substrate, a TAC substrate manufactured by Fuji Film Co., Ltd., trade name TD80UL (thickness 80 μm) was used.

The viscosity of the first composition and the second composition was MCR301 manufactured by Anton Paar, the measurement jig was PP50, the measurement temperature was 25 ° C., and the shear rate was 10,000 [1 / s]. Under the conditions, an appropriate amount of the composition to be measured (ink) was dropped on the stage and measured.
The dry film thickness was measured by placing a sample to be measured on glass using a trade name DIGIMATIC INDICATOR CODE 215-403 manufactured by Mitutoyo.
Abbreviations for each compound are as follows.
PETA: pentaerythritol triacrylate MIBK: methyl isobutyl ketone IPA: isopropanol TAC: triacetyl cellulose

(Preparation of first curable resin composition for hard coat layer)
The components of the compositions shown below were respectively blended to prepare first hard coat layer curable resin compositions 1 and 2 and second hard coat layer curable resin composition 1.

(First curable resin composition for hard coat layer 1)
Beam set DK1: 64.72 parts by mass (48.54 parts by mass in terms of solid content)
Irg184: 1.94 parts by mass MCF350-5: 0.97 parts by mass (0.05 parts by mass in terms of solid content)
MIBK: 32.36 parts by mass

(First curable resin composition for hard coat layer 2)
PETA: 75.49 parts by mass (56.62 parts by mass in terms of solid content)
Irg184: 3.02 parts by mass MCF350-5: 3.02 parts by mass (0.15 parts by mass in terms of solid content)
MIBK: 18.47 parts by mass

(Second curable resin composition for hard coat layer 1)
Through rear DAS: 75.81 (solid content conversion 15.16 parts by mass)
Beam set DK1: 13.48 parts by mass (solid content equivalent: 10.11 parts by mass)
Irg184: 0.61 parts by mass MCF350-5: 10.11 parts by mass (0.51 parts by mass in terms of solid content)

(Second curable resin composition for hard coat layer 2)
Through rear DAS: 83.12 (solid content conversion 16.62 parts by mass)
Beam set DK1: 15.83 parts by mass (solid content conversion: 11.87 parts by mass)
Irg184: 0.48 parts by mass MCF350-5: 0.57 parts by mass (solid content conversion 0.03 parts by mass)

(Second curable resin composition for hard coat layer 3)
Through rear DAS: 73.95 (14.79 parts by mass in terms of solid content)
Beam set DK1: 24.65 parts by mass (18.49 parts by mass in terms of solid content)
Irg184: 0.74 parts by mass MCF350-5: 0.67 parts by mass (0.03 parts by mass in terms of solid content)

(Second curable resin composition for hard coat layer 4)
LINC-3A: 78.63
Irg184: 3.15 parts by mass MCF350-5: 15.73 parts by mass (0.79 parts by mass in terms of solid content)
MIBK: 2.49 parts by mass

(Production of optical film)
Example 1
The solvent was distilled off from the first curable resin composition for hard coat layer 1 and the second curable resin composition for hard coat layer 1 using an evaporator, and the viscosity was adjusted to 30 mPa · s. Next, on the TAC substrate (TD80UL) conveyed at a speed of 1 m / min, the first curable resin composition for hard coat layer 1 and the second curable resin composition for hard coat layer are formed from the TAC substrate side. Two layers were simultaneously applied so that the product 1 was located. At this time, the wet film thicknesses of the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 1 were 20 μm and 10 μm, respectively.
Next, the two-layer coating film is dried at 70 ° C. for 60 seconds, and the coating film is cured by irradiating with ultraviolet rays so that the integrated light amount becomes 120 mJ / cm ² in a nitrogen atmosphere. A 10 μm thick hard coat layer was formed to produce an optical film.

(Comparative Example 1)
In Example 1, the second curable resin composition 1 for hard coat layer was not used, but only the first curable resin composition 1 for hard coat layer was applied with a wet film thickness of 20 μm, and a dry film thickness of 9 μm was applied. An optical film was produced in the same manner as in Example 1 except that the hard coat layer was formed.

(Comparative Example 2)
In Example 1, the first curable resin composition for hard coat layer 1 was not used, but only the second curable resin composition for hard coat layer 1 was applied with a wet film thickness of 20 μm, and a dry film thickness of 10 μm was applied. An optical film was produced in the same manner as in Example 1 except that the hard coat layer was formed.

(Comparative Example 3)
In Example 1, only the first curable resin composition 1 for hard coat layer was applied with a wet film thickness of 20 μm, the coating film was dried at 70 ° C. for 60 seconds, and ultraviolet rays were accumulated in a nitrogen atmosphere. There is cured by irradiating the coating film to be 120 mJ / cm ^2, then, only the second hard coat layer curable resin composition 1 was applied with a wet film thickness of 10μm on the cured film, the coating The film was dried at 70 ° C. for 60 seconds, and the coating film was cured by irradiating with ultraviolet rays so that the integrated light amount became 120 mJ / cm ² in a nitrogen atmosphere, thereby forming a hard coat layer having a total dry film thickness of 10 μm. Except for the above, an optical film was produced in the same manner as in Example 1.

(Example 2)
The viscosity of each of the first curable resin composition for hard coat layer 1 and the second curable resin composition for hard coat layer 2 was adjusted to 10 mPa · s. Next, on the TAC substrate (TD80UL) conveyed at a speed of 20 m / min, the first curable resin composition for hard coat layer 1 and the second curable resin composition for hard coat layer are formed from the TAC substrate side. Two layers were simultaneously applied so that the product 2 was located. At this time, the wet film thicknesses of the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 2 were 25 μm and 5 μm, respectively.
Next, the two-layer coating film is dried at 70 ° C. for 60 seconds, and the coating film is cured by irradiating with ultraviolet rays so that the integrated light amount becomes 120 mJ / cm ² in a nitrogen atmosphere. A hard coat layer having a thickness of 11 μm was formed to produce an optical film.

(Example 3)
In Example 2, the wet film thicknesses of the first curable resin composition 1 for hard coat layer 1 and the second curable resin composition 2 for hard coat layer 2 were 25 μm and 1 μm, respectively, and the dry film thickness was An optical film was produced in the same manner as in Example 2 except that an 8 μm hard coat layer was formed.

Example 4
In Example 2, the wet film thicknesses of the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 2 were 18.75 μm and 3.75 μm, respectively. An optical film was produced in the same manner as in Example 2 except that a hard coat layer having a dry film thickness of 6 μm was formed.

(Comparative Example 4)
In Example 2, the second hard coat layer curable resin composition 2 was not used, but only the first hard coat layer curable resin composition 1 was applied with a wet film thickness of 20 μm, and the dry film thickness of 11 μm was applied. An optical film was produced in the same manner as in Example 2 except that a hard coat layer was formed.

(Comparative Example 5)
In Example 2, the first curable resin composition for hard coat layer 1 was not used, but only the second curable resin composition for hard coat layer 2 was applied at a wet film thickness of 10 μm, and the dry film thickness was 5 μm. An optical film was produced in the same manner as in Example 2 except that a hard coat layer was formed.

(Comparative Example 6)
In Example 2, after simultaneous application of the first curable resin composition 1 for hard coat layer and the second curable resin composition 2 for hard coat layer, and before drying, an integrated amount of ultraviolet rays is applied in a nitrogen atmosphere. An optical film was produced in the same manner as in Example 2 except that irradiation (precure) was performed so that was 50 mJ / cm ² .

(Example 5)
The viscosity of each of the first curable resin composition for hard coat layer 1 and the second curable resin composition for hard coat layer 3 was adjusted to 10 mPa · s. Next, on the TAC substrate (TD80UL) conveyed at a speed of 20 m / min, the first curable resin composition for hard coat layer 1 and the second curable resin composition for hard coat layer are formed from the TAC substrate side. Two layers were simultaneously applied so that the object 3 was located. At this time, the wet film thicknesses of the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 3 were 25 μm and 5 μm, respectively.
Next, the two-layer coating film is dried at 70 ° C. for 60 seconds, and the coating film is cured by irradiating with ultraviolet rays so that the integrated light amount becomes 120 mJ / cm ² in a nitrogen atmosphere. A 9 μm thick hard coat layer was formed to prepare an optical film.

(Example 6)
In Example 5, the wet film thicknesses of the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 3 were 25 μm and 1 μm, respectively, and the dry film thickness was An optical film was produced in the same manner as in Example 5 except that an 8 μm hard coat layer was formed.

(Example 7)
In Example 5, the wet film thicknesses of the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 3 were 18.75 μm and 3.75 μm, respectively. An optical film was produced in the same manner as in Example 5 except that a hard coat layer having a dry film thickness of 5 μm was formed.

(Comparative Example 7)
In Example 5, the first curable resin composition 1 for hard coat layer was not used, but only the second curable resin composition 3 for hard coat layer was applied with a wet film thickness of 10 μm, and the dry film thickness of 5 μm was applied. An optical film was produced in the same manner as in Example 5 except that the hard coat layer was formed.

(Example 8)
The viscosity of each of the first curable resin composition 2 for hard coat layer 2 and the second curable resin composition 4 for hard coat layer was adjusted to 30 mPa · s. Next, on the TAC substrate (TD80UL) conveyed at a speed of 1 m / min, the first curable resin composition 2 for the hard coat layer and the second curable resin composition for the hard coat layer are formed from the TAC substrate side. Two layers were simultaneously applied so that the product 4 was located. At this time, the wet film thicknesses of the first hard coat layer curable resin composition 2 and the second hard coat layer curable resin composition 4 were 20 μm and 10 μm, respectively.
Next, the two-layer coating film is dried at 25 ° C. for 60 seconds, and the coating film is cured by irradiating with ultraviolet rays so that the integrated light amount becomes 120 mJ / cm ² in a nitrogen atmosphere. A 14 μm thick hard coat layer was formed to produce an optical film.

Example 9
In Example 8, an optical film was produced in the same manner as in Example 8, except that the drying temperature of the two-layer coating film was 50 ° C.

(Example 10)
In Example 8, an optical film was produced in the same manner as in Example 8, except that the drying temperature of the two-layer coating film was 70 ° C.

(Example 11)
In Example 8, an optical film was produced in the same manner as in Example 8, except that the drying temperature of the two-layer coating film was 100 ° C.

(Example 12)
In Example 10, except that the wet film thicknesses of the first hard coat layer curable resin composition 2 and the second hard coat layer curable resin composition 4 were 25 μm and 5 μm, respectively. An optical film was produced in the same manner as in Example 10.

(Comparative Example 8)
In Example 10, the second hard coat layer curable resin composition 4 was not used, but only the first hard coat layer curable resin composition 2 was applied with a wet film thickness of 20 μm, and the dry film thickness of 9 μm was applied. An optical film was produced in the same manner as in Example 10 except that the hard coat layer was formed.

(Comparative Example 9)
In Example 10, without using the first curable resin composition 2 for hard coat layer, only the second curable resin composition 4 for hard coat layer was applied with a wet film thickness of 10 μm, and the dry film thickness was 8 μm. An optical film was produced in the same manner as in Example 10 except that the hard coat layer was formed.

(Example 13)
In Example 1, the viscosities of the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 1 were adjusted to 90 mPa · s, respectively, The hard film thicknesses of the coating films of the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 3 were 25 μm and 5 μm, respectively, and the dry film thickness was 18 μm. An optical film was produced in the same manner as in Example 1 except that the layer was formed.

(Comparative Example 10)
In Example 1, the viscosity of each of the first curable resin composition for hard coat layer 1 and the second curable resin composition for hard coat layer 1 is adjusted to 4 mPa · s, and the dry film thickness An optical film was produced in the same manner as in Example 1 except that a 5 μm hard coat layer was formed.

(Comparative Example 11)
In Example 1, the viscosities of the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 1 were adjusted to 10 mPa · s and 4 mPa · s, respectively. An optical film was produced in the same manner as in Example 1 except that a hard coat layer having a dry film thickness of 9 μm was formed.

(Comparative Example 12)
In Example 1, the viscosities of the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 1 were adjusted to 62 mPa · s and 10 mPa · s, respectively. An optical film was produced in the same manner as in Example 1 except that a hard coat layer having a dry film thickness of 17 μm was formed.

(Comparative Example 13)
In Example 1, the first hard coat layer curable resin composition 1 and the second hard coat layer curable resin composition 1 were adjusted to have a viscosity of 10 mPa · s, respectively. The same amount of the two compositions used in Example 1 were mixed and the mixed composition was coated on a TAC substrate. At this time, the wet film thickness of the coating film of the mixed composition was set to 30 μm.
Subsequently, the coating film was dried and irradiated with light in the same manner as in Example 1 to form a hard coat layer having a dry film thickness of 10 μm, thereby producing an optical film.

  Table 1 below summarizes the types of compositions, wet film thickness, coating method, dry film thickness and drying conditions used in the above Examples and Comparative Examples, and the transport speed of the TAC substrate.

(Evaluation of optical film)
About the optical film of the said Example and comparative example, it measured about the reflectance, the haze (Hz), and the total light transmittance as shown below, respectively. Moreover, about the optical film of the said Example and comparative example, the interference fringe was evaluated as shown below, respectively. The results are shown in Table 2.
Moreover, the cross-sectional photograph of the optical film of Example 1 is shown in FIGS. 7 and 8, and the cross-sectional photograph of the optical film of Comparative Example 3 is shown in FIG. 8 is an enlarged view of the interface side of the HC layer opposite to the TAC substrate in the photograph of FIG.

(Measurement of reflectance)
The measurement of the reflectance is performed using a product name V7100 type UV-visible spectrophotometer manufactured by JASCO Corporation and a product name VAR-7010 absolute reflectance measurement device manufactured by JASCO Corporation with an incident angle of 5 °, The polarizer was N-polarized light, the measurement wavelength range was 380 to 780 nm, a black tape was bonded to the TAC substrate side of the optical film, and the measurement was performed by installing it on the apparatus. In addition, the average value of the measurement result calculated | required in the measurement wavelength range was made into the reflectance.

(Measurement of haze and total light transmittance)
The haze and total light transmittance were measured with a reflection / transmittance meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K-7136 and JIS K7361, respectively.

(Evaluation of interference fringes)
Using an interference fringe inspection lamp (Na lamp) manufactured by Funatec Co., Ltd., visual inspection was performed and the following criteria were evaluated.
○: Interference fringes were hardly observed. △: Interference fringes were blurred. ×: Interference fringes were clearly visible.

(Evaluation of adhesion)
About the optical film of the said Example and the comparative example, the measurement of the adhesion rate of the cross-cut adhesion test shown below was performed, respectively.
In addition, about the comparative example 12, surface shape was bad and it was not able to measure.
(Cross-cut adhesion test)
Put 100 square grids on the surface of the HC layer of the optical film in total of 1 mm square, perform 5 continuous peel tests using Nichiban Co., Ltd. industrial 24 mm cello tape (registered trademark), and calculate based on the following criteria The percentage of squares that remained without being peeled was determined.
Adhesion rate (%) = (number of cells not peeled / total number of cells 100) × 100

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

(Summary of results)
From Table 2, the reflectance and haze were all low in the examples. In the examples, the total light transmittance was as high as 91.5% or more. In all the examples, the generation of interference fringes was suppressed. Further, in the examples, adhesion and surface condition were also good. In particular, the surface conditions of Example 1 and Example 2 were good.
From FIG. 7 and FIG. 8 which are cross-sectional views of the optical film of Example 1, the hollow silica fine particles have a distribution that decreases from the opposite side (upper layer side) to the TAC substrate side of the HC layer from the TAC substrate side. From FIG. 8, it can be seen that most hollow silica fine particles are distributed from the interface of the HC layer on the side opposite to the TAC substrate to 5 μm.
7 to 9, in the case of Example 1, the boundary between the cured portion of the first composition and the cured portion of the second composition is not clear compared to Comparative Example 3. I understand.
However, in Comparative Example 1 corresponding to the case where there was no second composition in Example 1, the hollow silica fine particles were not included, and thus the reflectance was the same as that of only a general hard coat layer.
In Comparative Example 2 corresponding to the case where the first composition was not present in Example 1, interference fringes were generated and the adhesion rate was low. This is because the hollow silica fine particles contained in the second composition are uniformly distributed in the HC layer, and the refractive index difference between the TAC substrate and the hollow silica fine particles is large because it is located at the TAC substrate side interface of the HC layer. It is presumed that interference fringes have occurred. In addition, the presence of the hollow silica fine particles at the TAC substrate-side interface of the HC layer in this way presumes that the area where the resin of the HC layer penetrates and cures the TAC substrate is reduced and the adhesion is reduced. Is done.
In Comparative Example 3 corresponding to the case where sequential application was performed instead of simultaneous application in Example 1, the interference fringes were faintly observed. As shown in the cross-sectional photograph of FIG. 9, the boundary between the cured portion of the first composition and the cured portion of the second composition is clearly distinguished. It is estimated that this occurred.
In Comparative Example 4 corresponding to the case where there was no second composition in Example 2, the reflectance was the same as that of only a general hard coat layer as in Comparative Example 1.
In Comparative Example 5 corresponding to the case where the first composition was not present in Example 2, interference fringes were generated as in Comparative Example 2, and the adhesion rate was low.
In Comparative Example 6 corresponding to the case where precure was performed before drying in Example 2, the adhesion rate was low. This is because the curing (resin polymerization or crosslinking) of the first composition and the second composition proceeds by performing the pre-cure, and the first composition contained in the first composition on the TAC substrate side. This is presumably because this resin did not sufficiently penetrate into the TAC substrate.
In Comparative Example 7 corresponding to the case without the first composition in Example 5, interference fringes were generated as in Comparative Example 2, and the adhesion rate was low.
In Comparative Example 8 corresponding to the case where the second composition was not present in Example 10, the reflectance was the same as that of only a general hard coat layer as in Comparative Example 1.
In Comparative Example 9 corresponding to the case without the first composition in Example 10, interference fringes were generated as in Comparative Example 2, and the adhesion rate was low.
In Comparative Example 10 corresponding to the case where the viscosity of both the first composition and the second composition in Example 1 was small, the reflectance was lower than that of Comparative Example 1 and higher than that of Example 1. This is because the mixing of the two compositions proceeds due to the low viscosity of the two compositions, and the hollow silica fine particles present on the side opposite to the TAC substrate of the HC layer (upper layer side) are reduced and reflected. It is estimated that the rate has increased.
In Example 1, the surface shape was not good in Comparative Example 11 corresponding to the case where the viscosity of the second composition on the upper layer side of the HC layer was small.
In Comparative Example 12 corresponding to the case where the difference in viscosity between the first composition and the second composition is large in Example 1, a large amount of streaks on the surface of the HC layer occurs, the surface becomes not smooth, and light is not emitted. The reflectance, haze, and total light transmittance could not be measured due to scattering.
In Comparative Example 13 corresponding to the case where a uniform mixture of the first composition and the second composition in Example 1 was applied, the reflectance was the same as that of Comparative Example 10. Further, interference fringes were generated and the adhesion rate was low. This is presumed that the two silica compositions were uniformly mixed and applied, so that the hollow silica fine particles present on the opposite side of the HC substrate of the HC layer decreased as in Comparative Example 10, and the reflectance increased. Is done. Further, as in Comparative Example 2, it is presumed that interference fringes were generated due to the hollow silica fine particles being located at the TAC substrate side interface of the HC layer, and the adhesion rate was lowered.

DESCRIPTION OF SYMBOLS 1 Optical film 2 Polarizing plate 10 Light transmissive substrate 20 Hard coat layer 30 Low refractive index fine particle 40 Die head 51, 52 Slit 60 First hard coat layer curable resin composition 61 First hard coat layer curability Coating film 70 of resin composition Second curable resin composition for hard coat layer 71 Coating film 80 of second curable resin composition for hard coat layer Coater gap 90 Total wet of first and second compositions Film thickness 100 Conventional antireflection film 110 Conventional hard coat layer 120 Low refractive index layer 130 Transport direction 140 of transparent substrate Antistatic layer 150 Antifouling layer 160 Protective film 170 Polarizing layer 180 Polarizer

Claims (8)

(I) preparing a light transmissive substrate;
(Ii) including the reactive first resin and the first solvent, and does not include the low refractive index fine particles and the low refractive index resin or includes the low refractive index resin, the mass of the first resin And a first hard-coat layer curable resin composition having a viscosity μ1 of 3 mPa · s or more, a low refractive index fine particle having an average particle diameter of 10 to 300 nm, and a low refractive index resin. One or more low-refractive index components selected from the group consisting of a second resin having reactivity and a second solvent, the viscosity μ2 is 5 mPa · s or more, and the value obtained by subtracting the μ1 from the μ2 is 30 mPa A step of preparing a second hard coat layer curable resin composition that is s or less,
(Iii) At least the first curable resin composition for a hard coat layer and the second curable resin composition for a hard coat layer are provided on one side of the light transmissive substrate from the light transmissive substrate side. A process of applying them adjacent to each other to form a coating film;
(Iv) a step of drying the coating film obtained in the step (iii) and then curing by light irradiation and / or heating, and between the step (iii) and the step (iv) A method for producing an optical film, characterized by not performing precure.   In the step (iii), the wet film thickness of the first hard coat layer curable resin composition is T1, and the wet film thickness of the second hard coat layer curable resin composition is T2. The method for producing an optical film according to claim 1, wherein T2 / T1 is 0.01 to 1.   The viscosity μ1 of the first curable resin composition for hard coat layer is 3 to 95 mPa · s, and the viscosity μ2 of the second curable resin composition for hard coat layer is 5 to 100 mPa · s. The manufacturing method of the optical film of Claim 1 or 2 characterized by these.   The optical film obtained by the manufacturing method in any one of Claims 1 thru | or 3. An optical film provided with a hard coat layer on one side of a light-transmitting substrate,
In the film thickness direction of the hard coat layer, there are more low refractive index fine particles on the interface side opposite to the light transmissive substrate than on the light transmissive substrate side, and the light transmissive substrate. The amount of the low refractive index fine particles is smaller toward the side, and the low refractive index component is gradually reduced from the interface opposite to the light transmissive substrate to the light transmissive substrate side,
There is no layer interface in the hard coat layer,
5. The optical film according to claim 4, wherein an adhesion rate of the cross-coat adhesion test of the hard coat layer to the light-transmitting substrate is 90 to 100%.   70-100 of the total amount of the low refractive index fine particles in a region from the interface opposite to the light-transmitting substrate to 70% of the dry film thickness of the hard coat layer in the film thickness direction of the hard coat layer. % Optical film according to claim 4 or 5, characterized in that% is present.   A polarizing plate, wherein a polarizer is provided on the side of the optically transparent substrate opposite to the hard coat layer of the optical film according to any one of claims 4 to 6.   The display panel is arrange | positioned at the light transmissive base material side opposite to the said hard-coat layer of the optical film as described in any one of the said Claims 4 thru | or 6. The display characterized by the above-mentioned.