JP6131733B2 - Optical film manufacturing method and optical film - Google Patents

Description

  The present invention relates to a method for producing an optical film and an optical film capable of having a water / oil repellent function on the surface without causing coloring such as yellowing by electron beam irradiation.

In recent years, with the spread of portable information terminal devices such as mobile phones and tablet terminals, digital devices such as TVs and personal computers, and information terminals such as security systems, the information terminals include flat panel displays such as displays and organic EL displays, and touch panels. Such a display device is used.
In these display devices, an optical film is used in order to improve optical characteristics, mechanical properties such as scratch resistance and adhesion. The optical film has, for example, at least a transparent base material and an optical functional layer formed on the surface of the transparent base material, and reduces reflection of light generated on the screen of the display device by the optical functional layer. can do.

  The above-described information terminals are used in various situations, both indoors and outdoors, and many users operate by touching the display screen of the information terminals with their fingers. For this reason, the optical film used on the surface of the display screen has a problem that dirt such as fingerprints easily adheres, and the visibility and surface appearance are deteriorated and the optical characteristics are easily impaired. In addition, the dirt adhered to the display screen is difficult to wipe with dry wiping, and the information terminal or the like may be defective with water wiping. Therefore, an attempt has been made to improve the antifouling property of the image surface by providing a water / oil repellent layer as the outermost layer of the optical film.

  As a method of forming a water / oil repellent layer, a composition containing a water / oil repellent material (hereinafter sometimes referred to as “water / oil repellent layer composition”) is applied to the surface of an optical film to form a film. There is a method of curing the applied coating film (Patent Document 1). However, when a water / oil repellent layer is formed on the optical functional layer, depending on the material of the optical functional layer, the surface of the optical functional layer does not have a functional group that reacts with the water / oil repellent layer. There was a problem that no reaction occurred between the water / oil repellent layer and the optical functional layer, and sufficient adhesion could not be obtained.

JP 2000-284102 A

In order to improve the adhesion of the water / oil repellent layer, a method for improving the interlayer adhesion by irradiating the coating film with an electron beam has been studied. In this method, a water / oil repellent layer composition is applied onto an optical functional layer to form a coating film, and a radical is generated on the surface of the optical functional layer by irradiating an electron beam. In this method, the water- and oil-repellent layer is formed by graft polymerization of the polymer and a resin monomer of the water- and oil-repellent layer composition contained in the coating film.
According to the above method, even when the optical functional layer has no functional group on the surface, a polymerization reaction can be forced between the optical functional layer and the water / oil repellent layer, Interlayer adhesion can be improved. In addition, the radical polymerization caused by electron beam irradiation promotes the curing of the coating film composed of the optical functional layer and the water / oil repellent layer composition, so that a high-strength layer can be formed.
However, the above-mentioned method can form a water- and oil-repellent layer with high adhesion on the optical functional layer, but the optical film is colored by yellowing or the like due to electron beam irradiation, and the transparency of the entire optical film is impaired. There is a problem.

  The present invention has been made in view of the above circumstances, and a method for producing an optical film and an optical film capable of having a water / oil repellent function on a surface without causing coloring such as yellowing due to electron beam irradiation. The main purpose is to provide a film.

In order to achieve the above object, the present inventor examined the cause of yellowing and other coloration of an optical film by irradiation with an electron beam, and found that the optical film was colored in a transparent substrate. Furthermore, it specified that coloring of an optical film arises when an ultraviolet ray contained in a transparent base material is irradiated with an electron beam.
Therefore, the present inventor has found a method for forming a water- and oil-repellent layer by electron beam irradiation without causing coloring such as yellowing in the ultraviolet absorber contained in the transparent substrate, and has completed the present invention. .

  That is, the present invention provides a preparatory step of preparing a transparent substrate containing an ultraviolet absorber that is colored by irradiation with an electron beam, and an electron beam absorption that is not colored by irradiation of the electron beam on one surface of the transparent substrate. An electron beam absorbing layer forming step for forming a layer, an optical functional layer forming step for forming an optical functional layer on the electron beam absorbing layer, a water / oil repellent layer composition disposed on the optical functional layer, and the transparent And a water / oil repellent layer forming step of forming a water / oil repellent layer by irradiating the electron beam from a surface of the substrate having the electron beam absorbing layer. To do.

According to the present invention, in the electron beam absorption layer forming step, by forming the electron beam absorption layer between the transparent base material and the optical functional layer, the electron beam is not penetrated to the transparent base material, and the transparent base material is formed. The ultraviolet absorber contained in can be prevented from being irradiated with an electron beam. Thereby, it can prevent that a ultraviolet absorber produces coloring, such as yellowing. Further, in the optical functional layer forming step, the water and oil repellent layer can be irradiated with an electron beam with sufficient intensity to activate the surface of the optical functional layer without considering the occurrence of coloring in the transparent substrate. The degree of polymerization between the optical functional layer and the optical functional layer can be increased, and the adhesion can be improved.
This makes it possible to produce an optical film having a water / oil repellent layer on the surface without causing coloring such as yellowing.

  In the said invention, it is preferable that the said optical function layer is a layer which has a fine unevenness | corrugation on the surface. This is because if there are fine irregularities on the surface, the water / oil repellency function of the optical film is more emphasized.

  The present invention also includes a transparent substrate containing an ultraviolet absorber that is colored by irradiation with an electron beam, an electron beam absorbing layer that is formed on one surface of the transparent substrate and is not colored by irradiation with the electron beam, Provided is an optical film having an optical functional layer formed on the electron beam absorbing layer and a water / oil repellent layer formed on the optical functional layer.

  According to the present invention, by having the water- and oil-repellent layer on the optical functional layer, it can be easily removed even if dirt is attached to the surface, and has high antifouling property and high optical transparency. A film can be formed.

  According to the present invention, the thickness of the electron beam absorbing layer is adjusted according to the irradiation intensity of the electron beam, and the electron beam absorbing layer prevents the penetration of the electron beam into the transparent substrate. There is an effect that it is possible to form a water- and oil-repellent layer on the surface without coloring such as deformation.

It is process drawing which shows an example of the manufacturing method of the optical film of this invention. It is a schematic sectional drawing which shows an example of the optical film of this invention.

  Hereinafter, the method for producing an optical film and the optical film of the present invention will be described in detail.

A. First, the manufacturing method of the optical film of this invention is demonstrated. The method for producing an optical film of the present invention includes a preparation step of preparing a transparent substrate containing an ultraviolet absorber that is colored by irradiation of an electron beam, and coloring by irradiation of the electron beam on one surface of the transparent substrate. An electron beam absorbing layer forming step for forming an electron beam absorbing layer, an optical functional layer forming step for forming an optical functional layer on the electron beam absorbing layer, and a water / oil repellent layer composition disposed on the optical functional layer And a water / oil repellent layer forming step of forming the water / oil repellent layer by irradiating the electron beam from the surface having the electron beam absorbing layer of the transparent substrate. .

The method for producing the optical film of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram showing an example of a method for producing an optical film of the present invention.
In the method for producing an optical film of the present invention, as illustrated in FIG. 1, first, as a preparation step, a transparent substrate 1 containing an ultraviolet absorber that causes coloring such as yellowing by irradiation with an electron beam is prepared ( FIG. 1 (a)). Next, as an electron beam absorbing layer forming step, an electron beam absorbing layer composition containing a resin material or the like that is not colored by irradiation with an electron beam is applied to one surface of the transparent substrate 1, and the coating film is photocured. Thus, the electron beam absorbing layer 2 is formed (FIG. 1B). Subsequently, as the optical functional layer forming step, the optical functional layer 3 is formed by applying an optical functional layer composition containing a transparent resin or the like on the electron beam absorbing layer 2 and photocuring the coating film. (FIG. 1 (c)). Further, as the water / oil repellent layer forming step, the water / oil repellent layer composition 4a is arranged on the optical functional layer 3 by using a coating method or the like, and the electron from the side having the electron beam absorbing layer 2 of the transparent substrate 1 is arranged. The line X is irradiated (FIG. 1 (d)). At this time, since most of the electron beam X irradiated in the electron beam absorbing layer 2 is absorbed, occurrence of discoloration of the transparent substrate 1 can be suppressed. Thereby, the water / oil repellent layer 4 is fixed on the optical functional layer 3, and the target optical film 10 can be obtained (FIG.1 (e)).

  In an information terminal having an optical film, since dirt such as fingerprints adheres to the display screen, a water and oil repellent layer is provided as the outermost layer of the optical film to improve the antifouling property of the display screen. Thereby, even if dirt adheres to the surface of the optical film, it can be easily removed. As a method for forming a water / oil repellent layer on the optical functional layer, there is a method in which a water / oil repellent layer composition is applied to the surface of the optical functional layer and formed by photocuring, etc. Depending on the material used and the surface shape of the layer, there has been a problem that the water / oil repellent layer is not sufficiently formed into a film.

For example, depending on the material of the optical functional layer, since the surface of the layer does not have a functional group for reacting with the water / oil repellent layer, a method of simply applying the water / oil repellent layer composition to the surface of the optical functional layer and curing it Then, the material of the optical functional layer and the material of the water / oil repellent layer do not react with each other between the layers. For this reason, it has been difficult to have high adhesion between the optical functional layer and the water / oil repellent layer.
In addition, when the optical film has fine irregularities formed by aggregation of microprotrusions on the surface, the surface structure makes it easy for dirt to adhere to the surface. Tends to get worse. However, even if an attempt is made to form a water- and oil-repellent layer on the surface using a coating method or the like, it cannot be adhered to the entire surface of the fine protrusions, and it is difficult to improve the antifouling property.

As a method for improving the adhesion of the water / oil repellent layer to the optical functional layer, for example, after forming a coating film of the water / oil repellent layer composition on the optical functional layer, or when forming the film, Compatible with the surface of the optical functional layer as a water- and oil-repellent layer composition, a method of causing a polymerization reaction by electron beam or ultraviolet irradiation, a crosslinking reaction by heat, an acid-base reaction, etc. There are a method using a material, a method in which a surface treatment such as corona discharge, plasma discharge, and low energy electron beam irradiation is applied to the optical functional layer in advance.
Among them, a method of irradiating an application film of the water / oil repellent layer composition with an electron beam is preferable. This is by applying a water / oil repellent layer composition on the surface of the optical functional layer and irradiating it with an electron beam at a desired acceleration voltage, thereby generating a radical reaction on the surface of the optical functional layer and activating it, The water and oil repellent layer is formed by the resin monomer in the water and oil repellent layer composition starting from the radical to cause a graft polymerization reaction with the polymer of the optical functional layer.
According to the above-described method, even when the optical functional layer material or the layer surface does not have a functional group, a radical reaction can be forcedly caused on the layer surface. For this reason, it is not necessary to separately introduce a functional group into the optical functional layer, and the two layers can be brought into close contact with each other by simply causing a polymerization reaction between the optical functional layer and the water / oil repellent layer. Further, radical polymerization caused by electron beam irradiation promotes curing of the coating film composed of the optical functional layer and the water / oil repellent layer composition, so that a high-strength layer can be formed.
However, when the above method is used, a water- and oil-repellent layer can be formed on the optical functional layer with high adhesion by irradiation with an electron beam, but on the other hand, the optical film is colored such as yellowing and the transparency is impaired. There's a problem.

  Therefore, the present inventor has examined the cause of yellowing or the like in the optical film caused by electron beam irradiation, and found that the optical film is colored in the transparent substrate constituting the optical film. Moreover, it came to specify that coloring of an optical film arises by irradiating an electron beam to the ultraviolet absorber contained in the said transparent base material.

  First, the cause of yellowing caused by electron beam irradiation will be described. In general, it is known that yellowing occurs when a resin is irradiated with an electron beam, and the cause thereof is a conjugated π-electron system in the molecule (hereinafter sometimes abbreviated as a conjugated system). It is understood that it is due to the change in length. That is, when an electron beam is irradiated to any of a single bond, a double bond, and a triple bond in a resin molecule, a part or all of the bond is cleaved by secondary electrons generated from the electron beam. New bonds are generated within or between molecules. At this time, when the length of the conjugated system is extended, the absorption wavelength band of light is shifted to the long wavelength side, and coloring occurs.

The present inventor has also found that the yellowing of the optical film occurs due to the occurrence of the above-described phenomenon with respect to the ultraviolet absorber contained in the transparent substrate. For example, yellowing occurs when an electron beam is irradiated to a benzotriazole-based UV absorber in a transparent substrate, whereas yellowing does not occur when a triazine-based UV absorber is irradiated with an electron beam. Obtained knowledge. This is because when a benzotriazole ultraviolet absorber is irradiated with an electron beam, the N—N bond is cut and diazotization occurs, and a long π-electron conjugated system is formed, resulting in yellowing. In the absorbent, diazotization or the like does not occur even when irradiated with an electron beam, and a long π-electron conjugated system cannot be formed. Therefore, it is assumed that yellowing does not occur.
For this reason, UV absorbers have conjugated chains that extend due to their molecular structure, when secondary electrons generated by electron beam irradiation break some of the bonds in the molecule. It is assumed that coloring such as yellowing occurs.

The transparent substrate in the optical film needs to contain an ultraviolet absorber in order to have high weather resistance. Therefore, in the case where the ultraviolet absorber contained in the transparent substrate is one that causes conjugated coupling by irradiation with an electron beam, the irradiated electron beam is applied to the transparent substrate to prevent coloring of the transparent substrate. It is necessary to inhibit penetration.
Therefore, the present inventor further examined a method for forming a film by adhering a water / oil repellent layer without penetrating an electron beam to a transparent substrate.

  As a method for preventing the electron beam from penetrating to the transparent base material, there is a method for reducing the acceleration voltage of the electron beam. In this method, since the electron beam has a short range and does not reach the transparent base material, it is expected that the ultraviolet absorber contained in the transparent base material is not irradiated with the electron beam and coloring such as yellowing does not occur. . However, in this case, since the acceleration voltage of the electron beam is low, that is, the irradiation intensity is small, the surface of the optical functional layer is not sufficiently activated, and the generation of radicals as a starting point of the graft polymerization reaction is reduced. The oil repellent layer cannot be deposited in close contact.

Then, this inventor came to solve the said problem by providing an electron beam absorption layer between a transparent base material and an optical function layer. That is, since the electron beam range greatly contributes to the value of the acceleration voltage, by forming an electron beam absorption layer having a film thickness set based on the range of the electron beam assumed from the desired acceleration voltage, The energy of the electron beam is attenuated in the layer, and penetration into the transparent substrate can be inhibited. Thereby, since an electron beam is not irradiated to an ultraviolet absorber, it became possible to prevent coloring, such as yellowing by the change of a coupling | bonding mode.
In addition, in order to irradiate the optical function layer with an electron beam with sufficient intensity to activate the surface, a place where a radical polymerization is promoted and a graft polymerization reaction occurs between the water / oil repellent layer and the optical function layer. Will increase. This makes it possible to improve the adhesion between the water / oil repellent layer and the optical functional layer.

The present invention includes at least a preparation step, an electron beam absorbing layer forming step, an optical functional layer forming step, and a water / liquid repellent layer forming step.
Hereinafter, this invention is demonstrated for every process.

1. Preparation Step First, the preparation step in the present invention will be described. The preparatory step in the present invention is a step of preparing a transparent substrate containing an ultraviolet absorber that is colored by irradiation with an electron beam.

  As the resin material of the transparent substrate, a resin material generally used for an optical film can be used, but among them, when the transparent substrate in the present invention has a thickness described later, a resin having a low haze value is used. Preferably there is. In addition, the resin material may or may not cause yellowing or the like due to electron beam irradiation. For example, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as cyclic polyolefin, polyethylene, polypropylene and polystyrene, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, epoxy resins , Polycarbonate, acrylic resin, triazine resin, cellulose resin, acetyl cellulose resin such as triacetyl cellulose (TAC), polyethersulfone, polyurethane resin, urethane acrylate, polysulfone, polyether, polyether ketone, acrylonitrile , Methacrylonitrile, cycloolefin polymer, cycloolefin copolymer and the like can be used alone or in combination of two or more. Among these, TAC is preferably used in the present invention. This is because of excellent transparency and low birefringence.

  Moreover, the transparent base material used for an optical film normally contains a ultraviolet absorber. This is because when the transparent substrate does not contain an ultraviolet absorber, the resin used for the transparent substrate is deteriorated by irradiation with an electron beam, and the resulting optical film cannot have sufficient weather resistance. As the ultraviolet absorber contained in the transparent substrate, coloring such as yellowing is caused by irradiation with an electron beam from the viewpoint of further exerting the effects of the present invention. Examples of such ultraviolet absorbers include benzotriazole-based and phenol-based ones, among which benzotriazole-based ultraviolet absorbers are preferable.

  The benzotriazole-based ultraviolet absorber is an ultraviolet absorber having a benzotriazole skeleton. Specifically, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-butylphenyl) benzotriazole, 2- (2′-hydroxy-5′-). t-butylphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) benzotriazole 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chloro Examples include benzotriazole or 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole.

  The transparent substrate preferably has a transmittance in the visible light region of 80% or more, and more preferably 90% or more. Here, the transmittance of the transparent substrate can be measured based on JIS K7361-1.

The thickness of the transparent substrate can be appropriately set according to the use of the optical film of the present invention, and is not particularly limited, but is preferably in the range of 10 μm to 1000 μm, and more preferably in the range of 20 μm to 500 μm. In particular, the range of 60 μm to 80 μm is preferable.
Further, the transparent substrate may be one supplied in a roll shape, one that does not bend to the extent that it can be wound, but one that curves by applying a load, or one that does not bend completely.

  The transparent substrate may be biaxially or uniaxially stretched or non-stretched. Moreover, the said transparent base material is not restricted to the structure which consists of a single layer, You may have the structure by which the several layer was laminated | stacked. When it has the structure by which the several layer was laminated | stacked, the layer of the same composition may be laminated | stacked, and the several layer which has a different composition may be laminated | stacked.

  In this step, a physical surface such as an oxidation treatment is used to improve the adhesion between the transparent substrate and the electron beam absorbing layer formed in the subsequent “2. electron beam absorbing layer forming step”. Processing may be performed. In addition, a primer layer may be formed by previously applying an anchor agent or a primer agent that does not cause coloring or the like due to electron beam irradiation.

2. Electron Beam Absorbing Layer Forming Step Next, the electron beam absorbing layer forming step in the present invention will be described. The electron beam absorbing layer forming step in the present invention is a step of forming an electron beam absorbing layer that is not colored by irradiation with an electron beam on one surface of the transparent substrate.
Specifically, by applying an electron beam absorbing layer composition containing a resin material or the like that is not colored by electron beam irradiation to one surface of the transparent substrate prepared in the above preparation step, and curing the coating film In this step, an electron beam absorbing layer is formed.

(1) Electron beam absorbing layer First, the electron beam absorbing layer formed in this step will be described. The electron beam absorbing layer formed in this step is a layer that attenuates and absorbs the energy of the electron beam.

  The electron beam absorbing layer may be an organic layer mainly composed of an organic material or an inorganic layer mainly composed of an inorganic material. Hereinafter, each case will be described separately.

(A) When the electron beam absorbing layer is an organic layer When the electron beam absorbing layer is an organic layer, the resin material used may be a resin material that does not cause coloration such as yellowing when irradiated with an electron beam. That's fine. This is because the electron beam absorbing layer can be prevented from being colored, such as yellowing, by the irradiation of the electron beam, and the desired optical transparency can be maintained as the entire optical film. Such a resin material may be a thermosetting resin, a thermoplastic resin, or a photocurable resin.
Resin materials that do not cause coloration such as yellowing due to electron beam irradiation are “molecular structures that are not easily affected by electron beams” and “molecular structures that do not extend the length of conjugated systems even if they are affected by electron beams” And “a molecular structure in which formation of a chromophore or the like is difficult to occur upon irradiation with an electron beam” may be used.
Here, “a molecular structure that is not easily affected by an electron beam” refers to a molecular structure having a high binding energy, a molecular structure having a (4n + 2π) aromatic ring, or the like. In addition, “a molecular structure in which the length of the conjugated system does not extend even when affected by an electron beam” means that the length of the conjugated system is A molecular structure that basically does not extend from the conjugated chain.
Furthermore, “a molecular structure in which formation of a chromophore or the like is unlikely to occur due to electron beam irradiation” refers to C═C bond, C═O bond, C═N bond, N═N bond, N═O by electron beam irradiation. A structure or the like in which a chromophore such as a bond or an auxiliary chromophore such as a CH ₃ group, an NH ₂ group, an NHCH ₃ group, a COOH group, and an OH group is not easily generated.
Examples of the resin material having such a structure include triazine, triacetyl cellulose (TAC), urethane acrylate, polystyrene, polyurethane, polyester, polyethylene, epoxy resin, and cellulose.

The electron beam absorbing layer may contain an additive in addition to the resin material described above. The range of the electron beam is due to the acceleration voltage of the electron beam and the density of the electron beam absorption layer. By adding an additive to increase the density of the electron beam absorption layer, the acceleration voltage of the electron beam is increased. Even so, the energy of the electron beam is easily attenuated in the layer, and the range can be reduced.
The additive may be an organic additive or an inorganic additive as long as it has transparency and does not cause coloration such as yellowing when irradiated with an electron beam. .

An organic additive does not cause yellowing or other coloration due to electron beam irradiation, that is, a molecular structure having a high binding energy in the molecule, a molecular structure having a (4n + 2π) aromatic ring, or electron beam irradiation. Chromophores such as C = C bond, C = O bond, C = N bond, N = N bond, and N = O bond, or CH ₃ group, NH ₂ group, NHCH ₃ group, COOH group, OH group, etc. It is a low molecular compound having a molecular structure or the like that hardly generates an auxiliary color group. Such an additive may be any low-molecular non-polymerizable self-disintegrating compound, and examples thereof include a fluorine-based slip agent (product name: manufactured by Krytox Dupon).

  The inorganic additive is not particularly limited as long as it is colorless and transparent and does not cause coloring such as yellowing when irradiated with an electron beam. For example, the average primary particle diameter is about several tens of nm, especially 50 nm or less. Inorganic nanoparticles can be used. As the inorganic nanoparticles, those made of a metal or a metal compound are suitable. Specifically, gold, silver, copper, platinum, palladium, nickel, cobalt, iron, manganese, silicon, titanium, zirconium, tungsten, molybdenum, chromium, zinc, aluminum and a metal composed of two or more of these, iron oxide, Silicon oxide, zirconium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, cobalt oxide, nickel oxide, cerium oxide, cupric oxide, zinc oxide, tin oxide, antimony oxide, titanium dioxide, Metal oxides such as aluminum oxide and mixtures thereof, metal nitrides such as aluminum nitride, gallium nitride, titanium nitride, silicon nitride, titanium nitride and mixtures thereof, cadmium sulfide, zinc sulfide, copper sulfide, molybdenum sulfide and mixtures thereof, etc. In addition to metal sulfides, metal carbides, Genus borides, metal carbonates, zeolites, clays, and their complexes and the like.

  The shape of these inorganic nanoparticles is not particularly limited, and is granular, such as spherical, elliptical, tetragonal, such as a rectangular parallelepiped or rectangular parallelepiped; polygonal plate, such as a cylinder, disk, ellipsoid, or scale; A needle shape is preferred.

  In addition, although it does not specifically limit as content rate of the additive in an electron beam absorption layer, It is preferable that it is the quantity of the grade which does not affect the haze value and total light transmittance of the target optical film.

  The electron beam absorbing layer may contain an ultraviolet absorber in addition to the resin material described above, but it absorbs ultraviolet rays that are colored by the electron beam irradiation described in the section “1. Preparatory Step”. Agents shall not be included.

Furthermore, the electron absorption layer may contain a photopolymerization initiator in addition to the resin material described above. The photopolymerization initiator is transparent and does not cause yellowing or other coloring when irradiated with an electron beam, or is obtained when a desired content is added even when coloring occurs. It is preferable that the colored optical film is not recognizable.
Examples of such a photopolymerization initiator include alkylphenone series, acylphosphine oxide series, α-aminoketone series, benzophenone series, and oxime ester series. Among them, alkylphenone series and acylphosphine oxide series are preferable. Moreover, these photoinitiators may be used individually by 1 type, and may use 2 or more types together.

  Specific examples of the alkylphenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-dimethoxy-2-phenylacetophenone 2 -Methyl-1- [4- (methylthio) phenyl] -2-morpholino-propanone-1, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecyl) Phenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, diethoxyacetophenone, 2,2-di-sec-butoxy Examples include acetophenone and diethoxy-phenylacetophenone. These may be used alone or in combination of two or more.

  Acylphosphine oxide photopolymerization initiators include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (lucillin TPO), bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis- ( 2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and the like. These may be used alone or in combination of two or more.

  In addition, the content of the ultraviolet absorber and the photopolymerization initiator in the electron beam absorbing layer is not particularly limited as long as it does not deteriorate the optical characteristics of the optical film, and the resin materials and additives described above are not limited. It can be set according to the amount.

(B) When the electron beam absorbing layer is an inorganic layer When the electron beam absorbing layer is an inorganic layer, the electron beam absorbing layer can have a high density with a small film thickness. It becomes easy to attenuate. For this reason, even if the acceleration voltage of the electron beam is increased, the range can be reduced.
At this time, the material for the electron beam absorbing layer may be an inorganic material that is colorless and transparent and capable of forming a film with high density. For example, a metal or a metal compound used for the inorganic nanoparticles described above can be used.

(C) Electron Beam Absorbing Layer As the film thickness of the electron beam absorbing layer, the irradiation intensity of the electron beam irradiated in “4. Water and oil repellent layer forming step” described later, and the energy of the electron beam in the electron beam absorbing layer It is appropriately set according to the absorption capacity. Specifically, the film thickness of the electron beam absorbing layer can be set by calculating the range of the electron beam at a predetermined acceleration voltage from the following mathematical formula (1).

（数式（１）において、Ｒは飛程（μｍ）、Ｖは電子線の加速電圧（ｋＶ）、σは電子線吸収層の密度（ｇ／ｃｍ^３）である。）

(In Equation (1), R is the range (μm), V is the electron beam acceleration voltage (kV), and σ is the electron beam absorption layer density (g / cm ³ ).

For example, when the acceleration voltage (V) of the electron beam is 200 kV, the range of the electron beam in the electron beam absorbing layer (organic layer) having a density (σ) of 1.30 g / cm ³ is obtained from the above equation (1). About 351 μm. At this time, in the actual electron beam absorbing layer, the absorption of the electron beam is almost completed at a position of about 300 μm from the surface on the electron beam irradiation source side. This is because the above formula (1) is not a calculation formula taking into account the distance from the irradiation window of the electron beam irradiation source to the surface of the electron beam absorption layer, and the calculated range is a theoretical value. The actual range in the electron beam absorbing layer is smaller than the theoretical value calculated from Equation (1).
Therefore, the film thickness of the electron beam absorbing layer is set based on the theoretical range of the electron beam calculated from the above formula (1), thereby sufficiently absorbing the electron beam in the electron beam absorbing layer. Is possible. Further, the lower limit of the thickness of the electron beam absorbing layer depends on the distance from the irradiation window of the electron beam irradiation source to the electron beam absorbing layer, the degree of vacuum in the electron beam irradiation environment, and the like. Therefore, it is necessary to appropriately set a value obtained by removing these adjustments from the theoretical range calculated from the above formula (1). In addition, when the acceleration voltage of an electron beam and the density of an electron beam absorption layer are the above-mentioned conditions, it is preferable that it is in the range of 10 micrometers-360 micrometers as a film thickness of an electron beam absorption layer.

The density of the electron beam absorbing layer can be appropriately designed according to the acceleration voltage of the electron beam, etc., but the higher the density is preferable. As described above, the range of the electron beam is due to the acceleration voltage of the electron beam and the density of the electron beam absorbing layer. Therefore, even if the acceleration voltage of the electron beam is high, if the density of the electron beam absorbing layer is high, the energy of the electron beam is easily attenuated in the layer, and the range can be reduced. . At the same time, the electron beam absorbing layer can be designed to have a small thickness.
The density of the electron beam absorbing layer is not particularly limited as long as the desired optical film can be wound in a roll shape, and is not particularly limited. The film thickness of the electron beam absorbing layer necessary for sufficiently attenuating the energy of the film may become too large, and the haze of the entire optical film may be reduced. Therefore, it is preferable to appropriately adjust the density of the electron absorption layer of the electron beam so that the electron beam can be sufficiently absorbed without degrading the optical properties of the optical film.

  The electron beam absorbing layer is usually composed of either the organic layer or the inorganic layer described above, but may be a combination of the organic layer and the inorganic layer.

(2) Electron Beam Absorbing Layer Forming Step In this step, the acceleration voltage of the electron beam irradiated in the water / oil repellent layer forming step described later is defined, and based on the value of the acceleration voltage and the formula (1) described above. It is preferable to calculate the electron beam range and the film thickness of the electron beam absorption layer, and form the electron beam absorption layer so as to obtain the film thickness.

When the electron beam absorbing layer composition is mainly composed of the above-described organic material, the electron beam absorbing layer composition containing the above material is placed on the transparent substrate so that the film thickness after curing is the calculated value. The electron beam absorbing layer having a film thickness corresponding to the acceleration voltage of the electron beam can be formed by applying and curing the film.
The electron beam absorbing layer composition may be mixed with a solvent in order to facilitate application. The viscosity at this time is not particularly limited as long as it is a viscosity capable of forming a coating film on the surface of the transparent substrate by a coating method described later.

  As a method for applying the electron beam absorbing layer composition, known coating methods such as roll coating, gravure coating, comma coating, die coating, and bar coating can be used.

  The method for curing the coating film of the electron beam absorbing layer composition can be appropriately selected depending on the type of the resin material described above, and may be either heat curing or photocuring, but among them, photocuring with ultraviolet rays is preferable. As ultraviolet irradiation conditions, general curing conditions using ultraviolet rays can be used.

  In addition, when the electron beam absorbing layer composition is mainly composed of the above-mentioned inorganic materials, the electron beam absorption is performed so that the calculated film thickness is obtained by sputtering, CVD, vacuum deposition, ion plating, or the like. The layer is preferably formed on a transparent substrate. This is because the electron beam absorbing layer can be formed with high density.

3. Optical functional layer forming step Next, the optical functional layer forming step in the present invention will be described. The optical functional layer forming step in the present invention is a step of forming an optical functional layer on the electron beam absorbing layer.
Specifically, in the step of forming an optical functional layer by applying an optical functional layer composition containing a resin material or the like that is not colored by electron beam irradiation on the electron beam absorbing layer and curing the coating film. is there.

(1) Optical functional layer First, the optical functional layer formed in this step will be described. The optical functional layer formed in this step is a layer having an optical function such as a function of preventing reflection of light and a function of alleviating unevenness of diffusion of light. May be smooth, or may have a concavo-convex shape on the surface.
As such an optical functional layer, for example, a layer having fine irregularities formed by collecting microprotrusions on the surface (hereinafter referred to as “moth eye structure layer”), an anti-reflection coating layer (hereinafter referred to as “AR coating layer”). ), An antiglare layer, a hard coat layer having microprotrusions on the surface (hereinafter referred to as “low reflection hard coat layer”), and the like.
For example, when the optical functional layer is a moth-eye structure layer, it has a function of preventing light reflection by continuously changing the refractive index for light incident on the optical film and eliminating the discontinuous interface of the refractive index. Can do. Further, when the optical functional layer is an AR coating layer, it can have a function of suppressing reflection and reflection of light by suppressing reflection of external light itself. On the other hand, when it is an antiglare layer, it is formed on the display surface. The reflected light is diffusely reflected by the uneven shape, so that the reflected image can be made indistinct. Among them, the optical functional layer formed in this step is preferably a moth-eye structure layer. This is because if there are fine irregularities on the surface, the water and oil repellency function is more emphasized. In addition, if the optical functional layer is a moth-eye structure layer, it is possible to impart a concavo-convex shape to the surface without increasing the haze value of the optical film.
Hereinafter, the case where the optical functional layer is “(a) moth-eye structure layer” and the case where “(b) other optical functional layer” is described separately.

(A) Moss eye structure layer When the optical functional layer formed in this step is a moth eye structure layer, the resin material used is transparent and has an electron beam irradiation, similar to the electron beam absorption layer described above. Any resin material that does not cause coloring such as yellowing, that is, a resin material in which the length of the conjugated system does not extend in the molecular structure may be used. This is because the moth-eye structure layer can be prevented from being colored, such as yellowing, by the irradiation of the electron beam, and the desired optical transparency can be maintained as the entire optical film. Such a resin material may be a thermosetting resin, a thermoplastic resin, or a photocurable resin, and may be appropriately selected depending on the type of the target optical functional layer. Can do. Among these, a photocurable resin is preferable.

  Examples of the resin material include acrylic resin, polyester resin, (meth) acrylate resin, epoxy resin, polyolefin, styrene resin, polyamide, polyimide, polyamideimide, polyurethane, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polycarbonate, melamine resin, Examples include urea resin, alkyd resin, phenol resin, cellulose resin, diallyl phthalate resin, silicon resin, polyarate resin, polyacetal resin, and styrene-isoprene rubber. These resins may be used alone or in combination of two or more. Of these, (meth) acrylate resins are preferred.

  The (meth) acrylate resin may be a monofunctional (meth) acrylate having one (meth) acryloyl group in one molecule, or a polyfunctional acrylate having two or more (meth) acryloyl groups in one molecule. It may be a combination of a monofunctional (meth) acrylate and a polyfunctional (meth) acrylate. Among them, it is preferable to use a monofunctional (meth) acrylate and a polyfunctional (meth) acrylate in combination from the viewpoint that the physical properties described later can be exhibited and both the flexibility and the elastic restoring property of the microprotrusions are achieved.

Although it does not specifically limit as monofunctional (meth) acrylate, From the point which is excellent in the softness | flexibility of a microprotrusion, what has a C10 or more long chain alkyl group is preferable, and a C12 or more long chain alkyl group is especially preferable. It preferably has at least one of tridecyl (meth) acrylate and dodecyl (meth) acrylate. Monofunctional (meth) acrylic acid ester can be used individually by 1 type or in combination of 2 or more types. In addition, when using the monofunctional (meth) acrylate which has a C10 or more long-chain alkyl group, it has the characteristic of the compound which has a C10 or more long-chain alkyl group mentioned later.
As content of monofunctional (meth) acrylate, it is preferable to exist in the range of 5 mass%-40 mass% with respect to the total solid of an optical functional layer composition, Especially 10 mass%-30 mass% It is preferable to be within the range.

  In addition, the polyfunctional acrylate is not particularly limited, but a polyfunctional (meth) acrylate containing an alkylene oxide is preferable because the microprotrusions are excellent in flexibility and restorability. Among them, an ethylene oxide modified polyfunctional ( (Meth) acrylate is preferred. It is preferable that content of the said polyfunctional (meth) acrylate exists in the range of 10 mass%-95 mass% with respect to the total solid of an optical functional layer composition, Especially 15 mass%-90 mass% It is preferable to be within the range.

  When monofunctional (meth) acrylate and polyfunctional (meth) acrylate are used in combination, the proportion of (meth) acrylate resin is within the range of 5 to 30 parts by mass with respect to 100 parts by mass of polyfunctional acrylate. It is preferable that it is within a range of 10 to 15 parts by mass.

  Further, the resin material of the moth-eye structure layer may be the same as the resin material of the electron beam absorbing layer described in the above section “2. Electron beam absorbing layer forming step”. This is because the moth-eye structure layer and the electron beam absorbing layer can be formed as a single layer.

In addition to the resin material described above, the moth-eye structure layer preferably contains a compound having a long-chain alkyl group having 10 or more carbon atoms from the viewpoint that the fine protrusions are excellent in flexibility, and has a long chain having 12 or more carbon atoms. It is more preferable to contain a compound having an alkyl group.
Specific examples of the compound having a long chain alkyl group having 10 or more carbon atoms include compounds having decane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, and the like. In addition to the halogen atom, hydroxyl group, carboxy group, amino group, sulfo group, a substituent having an ethylenically unsaturated double bond such as a vinyl group or a (meth) acryloyl group, etc. You may have. In addition, when the compound which has a C10 or more long-chain alkyl group has a (meth) acryloyl group, the said compound can correspond also to the monofunctional (meth) acrylate mentioned above.

  When a compound having a long-chain alkyl group having 10 or more carbon atoms is used, the content of the compound is within the range of 5% by mass to 30% by mass with respect to the total solid content of the optical functional layer composition. Preferably, it is in the range of 10% by mass to 20% by mass.

  The moth-eye structure layer may contain a photopolymerization initiator in order to initiate or accelerate the curing reaction of the resin material. Any photopolymerization initiator may be used as long as it has transparency and does not cause yellowing or other coloration upon irradiation with an electron beam. The light described in the above-mentioned section “2. Electron Beam Absorbing Layer Forming Step”. A polymerization initiator can be used. As content of the said photoinitiator in a moth eye structure layer, it exists in the range of 0.8 mass%-20 mass% with respect to the total solid of an optical function layer composition, and 0.9 mass%-10 mass. % Is preferable.

  Further, the moth-eye structure layer may contain other materials as long as it does not cause yellowing or the like due to electron beam irradiation. Examples of such materials include ultraviolet absorbers, antistatic agents, stabilizers, antifoaming agents, anti-repelling agents, antioxidants, anti-aggregation agents, and viscosity adjusting agents.

The surface of the moth-eye structure layer has fine irregularities formed by collecting minute protrusions.
The shape of the microprojection is such that the cross-sectional area occupancy of the material portion forming the microprojection in the horizontal cross section when it is assumed that the microprojection is cut in a horizontal plane perpendicular to the depth direction of the microprojection is the top of the microprojection May be appropriately selected from those having a structure that gradually and gradually increases as it approaches the deepest portion. Specific examples of the shape of such microprojections include those having a vertical cross-sectional shape such as a semicircular shape, a semi-elliptical shape, a triangular shape, a parabolic shape, and a bell shape. The plurality of microprojections may have the same shape or different shapes. Since the fine protrusion has the above-described shape, the refractive index continuously changes in the depth direction such as fine unevenness, and thus antireflection properties are imparted.

  The period of the minute protrusions is not particularly limited as long as it is equal to or shorter than the wavelength in the visible light region, and can be appropriately determined. For example, it is preferably in the range of 80 nm to 400 nm, more preferably in the range of 100 nm to 300 nm, and still more preferably in the range of 120 nm to 250 nm. If the period of the minute protrusions is shorter than the above range, it may be difficult to form the minute protrusions with high accuracy. On the other hand, if the period of the minute protrusions is longer than the above range, the target optical film may have an insufficient antireflection function for light on the short wavelength side. In addition, the period of a microprotrusion means the distance between the vertices of an adjacent microprotrusion, observes the longitudinal cross section of a microprotrusion with an electron microscope, measures the period for ten pieces, and makes it the average value of the measured value. .

  Further, the height of the minute protrusions can be appropriately adjusted within a range in which a desired antireflection function can be imparted to the target optical film, and is not particularly limited, but is, for example, about 200 nm. Is preferred. If the height of the microprotrusions is too large, the individual microprotrusions may be easily damaged. On the other hand, if the height is too small, the antireflection function for light on the long wavelength side may be insufficient. The height of the microprojections refers to the height from the base of the projection to the apex, and is an average value determined by a method similar to the method for measuring the period of the microprojections described above.

  The aspect ratio of the fine protrusion (height of the fine protrusion / period of the fine protrusion) is preferably in the range of 0.8 to 2.5, and more preferably in the range of 0.8 to 2.1. Is more preferable.

  The moth-eye structure layer preferably has a storage elastic modulus (E) at 25 ° C. of 300 MPa or less. By setting the storage elastic modulus to 300 MPa or less, the microprotrusions are deformed by the pressure when wiping off the dirt attached to the surface of the target optical film, and the dirt that has entered the gaps between the microprotrusions is removed by dry wiping. Is possible. In particular, the storage elastic modulus (E) is preferably in the range of 1 MPa to 250 MPa, and more preferably in the range of 1 MPa to 100 MPa.

  At this time, the moth-eye structure layer has a ratio of loss elastic modulus (E ′) to storage elastic modulus (E) at 25 ° C. (tan δ (= E ′ / E), loss tangent) is 0.2 or less. It is preferable. By setting the loss tangent to 0.2 or less, the minute projections deformed when wiping off the dirt attached to the surface of the target optical film are elastically restored and easily return to the original shape. Thereby, the plastic deformation and sticking of the protrusions are suppressed, and the surface dirt can be removed without reducing the antireflection performance. Among them, tan δ is preferably 0.18 or less.

In addition, the said storage elastic modulus (E) and loss elastic modulus (E ') are measured with the following method based on JISK7244.
First, the optical functional layer composition is sufficiently cured by irradiating with an ultraviolet ray having an energy of 2000 mJ / cm ² for 1 minute or more, and a layer having a thickness of 1 mm, a width of 5 mm, and a length of 30 mm and having no irregular shape on the surface; To do. Next, E and E ′ at 25 ° C. are determined by applying a periodic external force of 25 g at 10 Hz in the length direction of the layer at 25 ° C. and measuring dynamic viscoelasticity. As the measuring device, for example, Rheogel E400 manufactured by UBM can be used.

The elastic modulus of the surface of the moth-eye structure layer is preferably in the range of 200 MPa to 500 MPa, more preferably in the range of 220 MPa to 400 MPa, from the viewpoint of excellent flexibility.
Further, the maximum indentation depth of the surface is preferably in the range of 1.0 μm to 2.0 μm from the viewpoint of being easily deformable and excellent in wiping property, and in particular in the range of 1.2 μm to 1.8 μm. It is preferable that
Further, the elastic recovery rate of the surface is preferably 80% or more, more preferably in the range of 85% to 98%, from the viewpoint that the plastic deformation is small and wiping marks are not easily generated.

The elastic modulus, maximum indentation depth, and elastic recovery rate of the moth-eye structure layer can be measured by pressing an indenter into the surface of the moth-eye structure layer under the following specific conditions. As the measuring apparatus, for example, PICODENER HM-500 manufactured by Fischer Instruments can be used.
<Measurement conditions>
・ Loading speed 1mN / 10 seconds ・ Holding time 10 seconds ・ Load unloading speed 1 mN / 10 seconds ・ Indenter Vickers ・ Measurement temperature 25 ℃

(B) Other optical functional layer When the optical functional layer formed in this step is other than the moth-eye structure layer, the resin material used is transparent and has an electron as in the case of the moth-eye structure layer described above. Any resin material that does not cause coloration such as yellowing due to irradiation of the wire may be used. The reason for this is the same as that described in the section “(a) Moss eye structure layer”. The resin material may be a thermosetting resin, may be a thermoplastic resin, and may be a photocurable resin, and among them, a photocurable resin is preferable.

  When the optical functional layer formed in this step is an anti-glare layer, the resin material is not particularly limited as long as the surface can be formed into an uneven shape, and conventionally used polymerization It can be used by appropriately selecting from a functional oligomer or prepolymer, and further includes a polyfunctional polymerizable oligomer or prepolymer. Examples of the polymerizable oligomer or prepolymer include oligomers and prepolymers having a radically polymerizable unsaturated group in the molecule, such as epoxy (meth) acrylate, urethane (meth) acrylate, and polyether urethane (meth) acrylate. Examples include caprolactone urethane (meth) acrylate, polyester (meth) acrylate, and polyether (meth) acrylate oligomers and prepolymers. These resins may be used alone or in combination of two or more. Here, (meth) acrylate refers to acrylate or methacrylate.

  Moreover, when the optical functional layer formed in this step is a low reflection hard coat layer, examples of the resin material include relatively low molecular weight polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, Oligomers or prepolymers of polyfunctional compounds such as alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, polyhydric alcohols, etc., and reactive diluents such as ethyl (meth) acrylate and ethylhexyl (meth) acrylate Monofunctional monomers such as styrene, methylstyrene, N-vinylpyrrolidone and polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate Over DOO, diethylene glycol di (meth) acrylate, pentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate. These may be used alone or in combination of two or more. Here, (meth) acrylate refers to acrylate or methacrylate.

  Further, when the optical functional layer formed in this step is an AR coat layer, as the resin material for forming the optical functional layer, materials usually used for the AR coat layer can be used.

  The resin material of the optical functional layer formed in this step is the same as the resin material of the electron beam absorbing layer described in the above section “2. Electron beam absorbing layer forming step” regardless of the type of the optical functional layer. There may be. In this case, the optical functional layer and the electron beam absorbing layer can be formed as a single layer. Moreover, since an electron beam can also be absorbed in the optical functional layer, the penetration of the electron beam into the transparent substrate can be further suppressed.

  Further, the optical functional layer may contain a photopolymerization initiator in addition to the resin material described above. About the kind etc. of a photoinitiator, it is the same as that of the content demonstrated by the term of the above-mentioned "(a) moth eye structure layer." In addition, about content of the said photoinitiator, it can set suitably.

  Further, the optical functional layer may contain other materials as long as it does not cause yellowing or the like due to electron beam irradiation. Such materials are the same as those described in the above-mentioned section “(a) Moss eye structure layer”.

(C) Optical functional layer The film thickness of the optical functional layer formed in this step is a size that can sufficiently exhibit the function of preventing the reflection of light, the function of reducing the uneven diffusion of light, and the like. Is preferred. Specifically, the film thickness of the optical functional layer is preferably in the range of 1 μm to 40 μm, more preferably in the range of 5 μm to 40 μm, and particularly preferably in the range of 5 μm to 10 μm. If the film thickness of the optical functional layer is smaller than the above range, it becomes difficult to form the optical functional layer in a desired film thickness, which may cause poor appearance in the target optical film. On the other hand, if it is larger than the above range, the optical functional layer may shrink due to electron beam irradiation, and the target optical film may be curled.
In addition, when the optical functional layer has an uneven shape such as fine unevenness on the surface, the film thickness refers to the length from the contact surface with the electron beam absorbing layer to the convex portion.

(2) Optical functional layer formation process In this process, in order to make application | coating easy, the optical functional layer composition containing the material of the optical functional layer mentioned above may be mixed with a solvent suitably. The viscosity at this time is not particularly limited as long as it is a viscosity capable of forming a coating film on the surface of the electron beam absorbing layer by a coating method described later.

  The solvent can be appropriately selected from those which can be dissolved or dispersed without reacting with each component of the optical functional layer composition. Examples of such solvents include hydrocarbon solvents such as benzene and hexane, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, tetrahydrofuran, 1,2-dimethoxyethane, propylene glycol monoethyl ether (PGME), and the like. Ether solvents, alkyl halide solvents such as chloroform and dichloromethane, ester solvents such as methyl acetate, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, amide solvents such as N, N-dimethylformamide, and dimethyl Examples include, but are not limited to, sulfoxide solvents such as sulfoxide, anan solvents such as cyclohexane, and alcohol solvents such as methanol, ethanol, and propanol. Moreover, the said solvent may be used independently and the mixed solvent of two or more types of solvents may be sufficient.

  Further, the ratio of the solid content to the total mass of the optical functional layer composition and the solvent is preferably in the range of 20% by mass to 70% by mass, and preferably in the range of 30% by mass to 60% by mass. More preferred. In addition, in this invention, solid content represents all the components of the optical function layer composition mixed with the solvent.

  A general method can be used as a coating method of the optical functional layer composition. As a coating method, for example, a known coating method such as roll coating, gravure coating, comma coating, die coating, or bar coating can be used.

  Further, when an optical functional layer having a concavo-convex shape on the surface, such as a moth-eye structure layer, is formed, the optical functional layer composition is applied on the electron beam absorbing layer, and the coating film has a desired concavo-convex shape. An optical functional layer having a desired concavo-convex shape can be formed on the surface by curing the coating film in a state in which the shaping plate is pressed and peeling the shaping plate after curing. The curing method may be heat curing or photocuring. Moreover, it does not specifically limit as a shape of the said shaping plate, For example, roll shape, flat plate shape, etc. can be used. About the pressure at this time and its loading method, it can set up suitably,

  The method for curing the optical functional layer in this step can be appropriately selected depending on the type of resin material contained in the optical functional layer composition, and may be either thermal curing or photocuring, and among them, photocuring with ultraviolet rays is preferable. As ultraviolet irradiation conditions, general curing conditions using ultraviolet rays can be used.

  Moreover, this process can also be made into the package process performed simultaneously with the electron beam absorption layer formation process mentioned above. That is, in this step, an optical functional layer having a thickness that can sufficiently attenuate the energy of the electron beam may be formed. By performing the collective process, the optical functional layer can also have the function of the electron beam absorbing layer, and the number of processes can be reduced. In addition, when the optical functional layer and the electron beam absorbing layer are individually laminated, light reflection may occur at the interface between the layers and the light transmittance of the entire optical film may be reduced. However, the optical functional layer should be a single layer. Thus, the occurrence of such a phenomenon can be prevented.

When the optical functional layer is formed by a collective process, the optical functional layer composition contains, in addition to the above-described materials, an additive that has transparency and does not cause coloring such as yellowing when irradiated with an electron beam. May be. By adding the additive, the density of the optical functional layer is increased, and even if the acceleration voltage of the electron beam is increased, the energy of the electron beam can be sufficiently attenuated in the layer.
The type of additive is the same as that described in the above-mentioned section “2. Electron beam absorption layer forming step”. At this time, the content of the additive in the optical functional layer is preferably the same as the content in the electron beam absorbing layer described in the above-mentioned section “2. Electron beam absorbing layer forming step”.
The density of the optical functional layer is preferably the same as that described in the above-mentioned section “2. Electron beam absorption layer forming step”.

  The film thickness of the optical functional layer formed by the batch process has the function of sufficiently absorbing the electron beam, the function of preventing the reflection of light, the function of reducing the uneven diffusion of light, etc. It is preferable that the size is as large as possible. Therefore, when the optical functional layer is formed by a collective process, the acceleration voltage is adjusted according to the same method as the method for setting the film thickness of the electron beam absorbing layer described in the section of “2. It is preferable to set the film thickness based on the range of the electron beam according to the intensity.

4). Water / oil repellent layer forming step Next, the water / oil repellent layer forming step in the present invention will be described. In the water / oil repellent layer forming step of the present invention, the water / oil repellent layer composition is disposed on the optical functional layer, and the electron beam is irradiated from the surface of the transparent substrate having the electron beam absorbing layer. This is a step of forming a water / oil repellent layer.

(1) Water / oil repellent layer First, the water / oil repellent layer formed in this step will be described. The water / oil repellent layer formed in this step has functions of both water repellency and oil repellency.
As a material for forming the water / oil repellent layer, a fluorine-based polymer, a silicon-based polymer, or the like can be used, and among these, a fluorine-based polymer is preferable. This is because the trifluoromethyl group (—CF ₃ ) contained in the fluoropolymer has the lowest surface energy and can exhibit very high water repellency.

  As the fluorine-based polymer, for example, a low polymerization compound of chlorotrifluoroethylene represented by the following general formula (1), an oxirane trifluoro (trifluoromethyl) homopolymer represented by the following general formula (2), or the like may be used. it can.

（一般式（１）中、ｎは６又は７である。一般式（２）中、ｎは７〜６０である。）

(In general formula (1), n is 6 or 7. In general formula (2), n is 7-60.)

  As the silicon-based polymer used for the water / oil repellent layer, a material generally used as a layer having water / oil repellency can be used, and examples thereof include TEGO Glide 400 (Sakai Industry Co., Ltd.).

  The film thickness of the water / oil repellent layer formed in this step is not particularly limited as long as it can exhibit the water / oil repellent function, but it is preferable that the film thickness is small. It is preferable that it is the magnitude | size which can exhibit.

(2) Water / oil repellent layer forming step The water / oil repellent layer composition used in this step includes the above-described water / oil repellent layer material. The arrangement method of the water / oil repellent layer composition is not particularly limited as long as it can form an uncured film containing the water / oil repellent layer composition on the optical functional layer. It may be a law.
As the vapor phase method, for example, a CVD method such as a plasma CVD method, a thermal CVD method, or a laser CVD method, a PVD method such as a vacuum deposition method, a sputtering method, or an ion plating method can be used.
Moreover, as a coating method, general methods, such as a gravure coat, a bar coat, a roll coat, a reverse roll coat, a comma coat, a die coat, a screen coat, can be used, for example. Among these, it is preferable to use a gravure coat. At this time, the water / oil repellent layer composition may be appropriately mixed with a solvent in order to facilitate application. The viscosity may be any viscosity as long as it allows the water / oil repellent layer composition to be coated on the surface of the optical functional layer by various coating methods, and can be adjusted as appropriate.

  In this step, the electron beam is irradiated from the surface having the electron beam absorbing layer of the transparent substrate. Thereby, the irradiated electron beam can generate many radicals on the optical functional layer. Moreover, since the penetration of the electron beam stops in the optical functional layer and the electron beam absorbing layer, the ultraviolet absorber contained in the transparent substrate cannot be reached, and coloring can be prevented. On the other hand, when the electron beam is irradiated from the surface of the transparent substrate that does not have the electron beam absorbing layer, since the transparent substrate is directly irradiated, coloring such as yellowing due to a change in the molecular structure of the ultraviolet absorber Will occur.

The acceleration voltage of the electron beam irradiated in this step is preferably within a range that can sufficiently activate the surface of the optical functional layer. The acceleration voltage of the electron beam is preferably in the range of 50 kV to 1000 kV, and more preferably in the range of 80 kV to 200 kV.
If the acceleration voltage of the electron beam is higher than the above range, the range of the electron beam exceeds the thickness of the electron beam absorbing layer formed in “2. Lines may penetrate. In addition, since it is necessary to make the film thickness of the electron beam absorbing layer larger than the range of the electron beam in order to prevent the penetration of the electron beam into the transparent substrate, the haze value or the like of the obtained optical film decreases. There is. On the other hand, if it is lower than the above range, the surface of the optical functional layer is not sufficiently activated, and the adhesion between the optical functional layer and the water / oil repellent layer may be low.

  Moreover, the irradiation dose of the electron beam irradiated in this process can be calculated by the following mathematical formula (2) according to a desired acceleration voltage.

（ここで、数式（２）において、Ｄは電子線照射線量（ｋＧｙ）、Ｖは加速電圧（ｋＶ）、Ｉは電流（ｍＡ）、νは機速（ｍ／ｍｉｎ）、ｋは機械固有値である。なお、ｋは実測値を元に算出される。）

(Here, in Equation (2), D is the electron beam irradiation dose (kGy), V is the acceleration voltage (kV), I is the current (mA), ν is the speed (m / min), and k is the machine eigenvalue. (Note that k is calculated based on actual measurement values.)

  The source of the electron beam used in this step is not particularly limited, and for example, curtain type, cockroft Walton type, bande graft type, resonant transformer type, insulated core transformer type, linear type, Various electron beam accelerators such as a dynamitron type, a high frequency type, and a line irradiation type can be used.

  In this step, when the electron beam is irradiated, the oxygen concentration is preferably 100 ppm or less. This is because irradiation with an electron beam in the presence of oxygen generates ozone and may adversely affect the environment. In order to set the oxygen concentration to 100 ppm or less, the electron beam may be irradiated under vacuum or an inert gas atmosphere such as nitrogen or argon. For example, by filling the inside of the electron beam irradiation apparatus with nitrogen, the oxygen concentration is 100 ppm or less. Can be achieved.

  In addition, the generation of radicals by electron beam irradiation in this step is performed using, for example, an electron spin resonance apparatus (ESR) to remove free radical species present at the interface between the water / oil repellent layer and the optical functional layer after electron beam irradiation. The occurrence can be confirmed by identification.

  In this step, the water / oil repellent layer composition is usually disposed on the optical functional layer and an electron beam is irradiated to form the water / oil repellent layer. Irradiation and the water / oil repellent layer composition may be disposed on the optical functional layer before the radicals are deactivated. Further, an electron beam may be irradiated on the optical functional layer, and a water / oil repellent layer separately formed before the radical is deactivated may be laminated.

6). Optical Film The optical film obtained by the present invention will be described in detail in the section “B. Optical Film” to be described later, and will not be described here.

B. Next, the optical film of the present invention will be described. The optical film of the present invention includes a transparent substrate containing an ultraviolet absorber that is colored by irradiation with an electron beam, an electron beam absorbing layer that is formed on one surface of the transparent substrate and is not colored by irradiation with an electron beam, An optical functional layer formed on the electron beam absorbing layer and a water / oil repellent layer formed on the optical functional layer.

  The optical film of the present invention will be described with reference to the drawings. FIG. 2 is a schematic sectional view showing an example of the optical film of the present invention. As illustrated in FIG. 2, the optical film 10 of the present invention is formed on a transparent substrate 1 containing an ultraviolet absorber that is colored by irradiation with an electron beam, and one surface of the transparent substrate 1, Having an electron beam absorbing layer 2 that is not colored by irradiation of an electron beam, an optical functional layer 3 formed on the electron beam absorbing layer 2, and a water / oil repellent layer 4 formed on the optical functional layer 3 It is. In the optical film 10 illustrated in FIG. 2, the optical functional layer 3 is a moth-eye structure layer, but the type of the optical functional layer 3 is not limited to this embodiment.

1. Optical Film The layers constituting the optical film of the present invention are the same as those described in the above-mentioned section “A. Method for producing optical film”, and thus the description thereof is omitted here.

  It is preferable that the optical film of the present invention can sufficiently transmit light. The visible light transmittance of the optical film is preferably 80% or more, and more preferably 90% or more. The total light transmittance is preferably 90% or more. The visible light transmittance and the total light transmittance are measured based on JIS K7361-1.

The optical film of the present invention preferably has a small change in hue (b ^* value) in the CIE LAB color system before and after irradiation with an electron beam. The b ^* value indicates the position between yellow and blue. If the b ^* value is negative, it means that the color is closer to blue, and if it is positive, it means that the color is closer to yellow. To do. Specifically, the difference (Δb ^* ) between the b ^* values before and after the electron beam irradiation is preferably less than 0.3, and more preferably less than 0.2. When the Δb ^* value is larger than the above range, the optical film becomes yellowish due to the irradiation of the electron beam, which may cause a decrease in light transmittance and an impediment to visibility.
In addition, said (DELTA ⁾ b ^* value is a value when it measures using a spectral color meter (Nippon Denshoku Industries Co., Ltd. SD-5000).

When the optical film of the present invention has a moth-eye structure layer as an optical functional layer, the storage elastic modulus (E) of the optical film at 25 ° C. and the loss elastic modulus (E ′) relative to the storage elastic modulus (E) at 25 ° C. It is preferable that the ratio (tan δ (= E ′ / E) loss tangent) has the value described in the above-mentioned section “A. Manufacturing method of optical film 3. Optical functional layer forming step”. The same applies to the elastic modulus, maximum indentation depth, and elastic recovery rate of the surface of the optical film when the optical film has a moth-eye structure layer as the optical functional layer.
When the optical film of the present invention has the above-described physical properties, when the dirt attached to the surface is wiped off, the deformed microprotrusions are elastically restored and easily return to the original shape. This is because the plastic deformation and sticking of the protrusions are suppressed, and the surface dirt can be removed without lowering the antireflection performance.

  The optical film of the present invention may have an electron absorption layer, an optical functional layer, and a water / oil repellent layer on one surface of a transparent substrate, and each layer described above on both sides of the transparent substrate. It may be.

2. Manufacturing Method As the manufacturing method of the optical film of the present invention, it is preferable to use the above-described “A. Manufacturing method of optical film”.

3. Use The optical film of the present invention has excellent water and oil repellency on the surface, and exhibits high light transmittance without causing coloring such as yellowing. For this reason, the optical film of the present invention is preferably used in applications where high optical properties are required and the surface is easily soiled by touching the surface directly with a finger or the like and antifouling properties are required. As such an application, it is particularly preferable to use it for an image display device provided with a touch panel member or the like.
Other applications include store windows, exhibition windows for museum exhibits, display windows for clocks and other measuring instruments, road signs, printed materials such as posters, vehicles such as automobiles and aircraft, Visibility can be improved by arranging it on the front or both sides of windows of various buildings. It can also be used as a window material for various optical devices such as glasses, cameras, telescopes, microscopes, and various illumination devices.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

(Preparation process)
The following three types were prepared as transparent substrates.
Base material 1: benzotriazole-based UV absorber-containing triacetyl cellulose film (TAC film) (film thickness: 80 μm, manufactured by Panac Corporation)
Base material 2: TAC film containing benzotriazole-based ultraviolet absorber (film thickness: 60 μm, manufactured by Panac Corporation)
Base material 3: TAC film containing no benzotriazole-based UV absorber (film thickness: 60 μm, manufactured by Panac Co., Ltd.)

  As an electron beam irradiation source, a curtain type electron beam irradiation device (manufactured by Iwasaki Electric Co., Ltd.) was prepared. The irradiation conditions are summarized in Table 1. The distance from the irradiation window of the electron beam irradiation apparatus to the evaluation object (in the case of a laminated body, the layer closest to the electron beam irradiation source) is 44.5 mm, and the same is applied to each irradiation condition.

(Verification 1: Coloring factor of base material by electron beam irradiation)
[Verification Example 1-1]
The substrate 2 was irradiated with an electron beam under condition A.

[Verification Example 1-2]
The substrate 3 was irradiated with an electron beam under condition A.

[Evaluation 1]
For Verification Example 1-1 and Verification Example 1-2, the difference in b ^* values before and after electron beam irradiation (Δb ^* value) was measured. A spectrocolorimeter SD-5000 (manufactured by Nippon Denshoku Industries Co., Ltd., measurement conditions: transmission, viewing angle 2 °, light source C) was used for measuring the Δb ^* value. A Δb ^* value of less than 0.3 was marked as ◯ (not colored), and a Δb ^* value of 0.3 or more (colored) as x. The results are summarized in Table 2.

表２より、検証例１−１ではΔｂ^＊値が３．７４、検証例１−２ではΔｂ^＊値が０．０１であることから、透明基材中に含まれる紫外線吸収剤の種類によって、上記紫外線吸収剤に電子線が照射されることにより黄変が生じることが確認された。

From Table 2, since Δb ^* value is 3.74 in Verification Example 1-1 and Δb ^* value is 0.01 in Verification Example 1-2, depending on the type of ultraviolet absorber contained in the transparent substrate, It was confirmed that yellowing occurred when the ultraviolet absorber was irradiated with an electron beam.

(Verification 2: Effect of coloring by electron beam acceleration voltage)
[Verification Example 2-1]
The substrate 1 was irradiated with an electron beam under condition D (acceleration voltage = 80 kV).

[Verification Example 2-2]
Except that the condition C (acceleration voltage = 100 kV) was used, the electron beam was irradiated in the same manner as in Verification Example 2-1.

[Verification Example 2-3]
Except that it was set as condition B (acceleration voltage = 200 kV), the electron beam was irradiated like the verification example 2-1.

[Evaluation 2]
About the verification example 2-1 to the verification example 2-3, the difference ((DELTA) b ^* value) of b ^* value before and behind electron beam irradiation was measured. The measurement method and the determination method are the same as in Evaluation 1 described above. The results are summarized in Table 3.

From Table 3, the Δb ^* value increased as the acceleration voltage was higher. From this, the range of the electron beam irradiation increases because the range of the electron beam becomes longer according to the acceleration voltage, and the irradiation depth of the electron beam into the transparent substrate increases. Confirmed to do. In other words, it was suggested that reducing the irradiation depth of the electron beam into the transparent base material is effective in combating yellowing.

(Setting of electron beam depth and electron beam absorption layer thickness)
[Examples 1 to 7, Comparative Example 1]
The laminate 1 (film thickness: 480 μm) in which eight substrates 2 (density (σ) = 1.30 g / cm ³ ) are stacked is irradiated with an electron beam under Condition E, and b ^* of each layer before and after the electron beam irradiation ^. The difference in values (Δb ^* value) was measured. In addition, with respect to each layer of the laminated body 1, the first layer as viewed from the electron beam irradiation source side is compared with the comparative example 1 and the second layer to the layer (8th layer) positioned farthest from the electron beam irradiation source. To Example 7. The b ^* value measurement method and determination method were the same as those in Evaluation 1 described above. The evaluation results are summarized in Table 4.

From Table 4, the Δb ^* value greatly changed in the first layer (Comparative Example 1) of the laminate 1. That is, it is presumed that the electron beam irradiated under the condition E penetrates into the depth of 60 μm from the surface on the electron beam irradiation source side and the yellowing of the ultraviolet absorber in the first layer has occurred. In the second and subsequent layers (Examples 1 to 7), since the Δb ^* value is less than 0.3, it is assumed that the electron beam has not penetrated. That is, when electron beam irradiation is performed under condition E, the penetration of the electron beam into the transparent substrate can be inhibited by forming an electron beam absorption layer having a film thickness of about 60 μm on the transparent substrate. It was suggested that it is possible to form an optical film that does not change. Note that the theoretical value of the range of the electron beam calculated from Equation (1) under Condition E was about 76 μm.

[Examples 8 to 18, Comparative Examples 2 to 6]
A laminate 2 (film thickness: 960 μm) in which 16 substrates 2 (density (σ) = 1.30 g / cm ³ ) are stacked is irradiated with an electron beam under condition A, and b ^* of each layer before and after the electron beam irradiation ^. The difference in values (Δb ^* value) was measured. In addition, about each layer of the laminated body 2, the 1st layer to the 5th layer as seen from the electron beam irradiation source side are referred to as Comparative Examples 2 to 6, and the layer located farthest from the electron beam irradiation source from the 6th layer. The steps up to (16th layer) were designated as Examples 8 to 18. The b ^* value measurement method and determination method were the same as those in Evaluation 1 described above. The evaluation results are summarized in Table 5.

From Table 5, the Δb ^* value greatly changed in the first to fifth layers (Comparative Examples 2 to 6) of the laminate. That is, it is presumed that the electron beam irradiated under the condition A penetrates within a depth of 300 μm from the surface on the electron beam irradiation source side, and yellowing of the ultraviolet absorber in the first to fifth layers has occurred. Further, since the Δb ^* value is less than 0.3 in the sixth and subsequent layers (Examples 8 to 18), it is assumed that the electron beam has not penetrated. That is, when electron beam irradiation is performed under condition A, the penetration of the electron beam into the transparent substrate can be inhibited by forming an electron beam absorbing layer having a film thickness of about 300 μm on the transparent substrate. It was suggested that it is possible to form an optical film that does not change. The theoretical value of the range of the electron beam calculated from Equation (1) under Condition A was about 351 μm.

  From the above results, by setting the film thickness of the electron beam absorbing layer provided on the transparent substrate based on the range of the electron beam according to the intensity of the acceleration voltage of the electron beam, the electron beam to the transparent substrate is set. Can be prevented and yellowing can be prevented. Thus, it was confirmed that an optical film that does not cause yellowing can be formed.

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Electron beam absorption layer 3 ... Optical functional layer 4 ... Water / oil repellent layer

Claims (3)

A preparation step of preparing a transparent base material containing an ultraviolet absorber colored by irradiation of an electron beam;
An electron beam absorbing layer forming step of forming an electron beam absorbing layer that is not colored by irradiation of the electron beam on one surface of the transparent substrate;
An optical functional layer forming step of forming an optical functional layer on the electron beam absorbing layer;
A water / oil repellent layer forming step of forming a water / oil repellent layer by irradiating the electron beam from the surface side of the water / oil repellent layer composition , disposing a water / oil repellent layer composition on the optical functional layer; A method for producing an optical film, comprising:   The method for producing an optical film according to claim 1, wherein the optical functional layer is a layer having fine irregularities on a surface. A transparent substrate containing an ultraviolet absorber that is colored by irradiation with an electron beam;
An electron beam absorbing layer formed on one surface of the transparent substrate and not colored by irradiation of the electron beam;
An optical functional layer formed on the electron beam absorbing layer;
A water / oil repellent layer formed on the optical functional layer;
An optical film having

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