JPH07168006A - Antireflection film, antireflection film and method for producing the same - Google Patents

Abstract

(57) [Summary] [Object] To provide an antireflection film and an antireflection film in which the refractive index is changed so as to increase stepwise from the outermost surface toward the transparent substrate. [Structure] An ultrafine particle layer is formed on a transparent substrate film directly or via an intermediate layer. To form this ultrafine particle layer, a dispersion liquid of ultrafine particles containing no binder resin may be applied, or dispersion of ultrafine particles having a binder resin having a weak surface tension that exposes the surface of the ultrafine particles. The liquid may be applied. The obtained coating film completely exposes the ultrafine particles without the coating of the binder resin on the surface thereof and forms the outermost surface layer of irregularities in which air and ultrafine particles are mixed.
The layer structure of the antireflection film is, in the example using the binder resin, an air layer 1 in contact with this film, an ultrafine particle / air mixed layer 2 which is the outermost layer of this film, then an ultrafine particle layer 3, and then The lowermost layer is composed of the ultrafine particle / binder mixed layer 4, and the refractive index gradually increases from the surface toward the substrate. Therefore, reflection of light can be effectively prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for preventing reflection of light on various surfaces such as curved mirrors, rearview mirrors, goggles, window glass, displays for personal computers and word processors, and other commercial displays. The present invention relates to an antireflection film itself attached to a substrate, an antireflection film formed by attaching the antireflection film to a transparent substrate film, and a method for producing the same.

[0002]

2. Description of the Related Art Reflection of light occurs at an interface where the refractive index changes abruptly. On the contrary, if the refractive index gradually changes at the interface, the reflection does not occur. Therefore, it is conventionally known that an effective antireflection effect can be obtained by forming a film that gradually changes from a refractive index close to that of a glass substrate to a refractive index close to that of air. As an antireflection film based on such a principle, for example, there is one described in JP-A-2-245702. In order to obtain such an antireflection film, the publication discloses a substance having a refractive index intermediate between that of the glass substrate and MgF ₂ , for example, ultrafine particles of SiO ₂ (refractive index 1.46) and MgF ₂ ultrafine particles. Mix and apply to a glass substrate, and gradually add Si from the glass substrate surface toward the coating film surface.
It has been shown that by decreasing the mixing ratio of O ₂ ultrafine particles and increasing the mixing ratio of MgF ₂ ultrafine particles, the change in the refractive index at the interface between the coated surface and the glass substrate becomes more gradual, and an antireflection effect is obtained. There is.

Further, Japanese Patent Laid-Open No. 5-13021 discloses that
In an antireflection film using ultrafine particles having a low refractive index such as MgF ₂ or SiO ₂ , the ultrafine particles have the smallest reflectance when regularly arranged on a transparent substrate at high density, and The different distribution of the refractive index in one layer of the antireflection film formed on the transparent substrate, the refractive index of the ultrafine particles on the air side from the outermost surface toward the transparent substrate,
It has been shown that there are types of refractive index on the ultrafine particle side and refractive index of the layer formed by the ultrafine particles and the binder.

[0004]

However, the antireflection film described in JP-A-2-245702 is formed by stacking coating films having different mixing ratios, and the film formation is complicated. Moreover, it was difficult to control the refractive index when preparing films having different refractive indexes.

Further, since the ultrafine particles in the outermost layer of the antireflection film of JP-A-5-13021 are covered with the binder resin, the ultrafine particles are refracted from the outermost surface of the antireflection film toward the transparent substrate. It is difficult to gradually increase the rate, and there is a problem that an effective reflection effect cannot be obtained. Further, the antireflection film described in this publication has a problem that the antireflection layer is formed by baking, and the base material to be applied is limited to one having heat resistance.

Therefore, in the present invention, the base material to be applied is not limited to the heat resistant base material in the one-coat antireflection film, and the refractive index is gradually defined from the outermost surface toward the transparent substrate. An object of the present invention is to provide an antireflection film that gradually changes, an antireflection film having the antireflection film, and a method for producing the same.

[0007]

In order to solve the above-mentioned problems, the present invention provides a surface layer portion in which air and ultrafine particles are mixed, in which the ultrafine particles are completely exposed to form an uneven surface, and An antireflection film composed of a portion consisting of ultrafine particles following the outermost layer, and the refractive index of the ultrafine particles is equal to or smaller than the refractive index of the base film to which the antireflection film is applied. The antireflection film having a refractive index is characterized in that the refractive index is gradually increased from the outermost surface layer to the lower part thereof.

In the present invention, the surface of the ultrafine particles is completely exposed to form an uneven surface having substantially no binder film. An antireflection film mainly composed of ultrafine particles, and an antireflection film composed of a part mainly composed of ultrafine particles and a part composed of ultrafine particles and a binder, and
The binder has a refractive index higher than the refractive index of the ultrafine particles, and has a refractive index lower than the refractive index of the substrate film to which the antireflection film is applied, the antireflection film from the outermost layer The antireflection film is characterized in that its refractive index is gradually increased toward the lower part.

The method for producing the antireflection film of the present invention is
By applying a dispersion liquid of ultrafine particles on a transparent substrate film, irregularities due to the ultrafine particles are formed in the outermost layer and a portion where the air and the ultrafine particles are mixed and the ultrafine particles are formed below the portion. A method for producing an antireflection film, which comprises forming an antireflection film having a portion.

The method for producing an antireflection film according to the present invention is a binder in which ultrafine particles are dispersed, has a refractive index higher than that of the ultrafine particles, and exposes the surface of the ultrafine particles. By coating a transparent base film with a binder having a low surface tension, the surface of the ultrafine particles is completely exposed and irregularities are formed to form the outermost layer in which air and ultrafine particles are mixed. A method for producing an antireflection film having a characteristic antireflection film formed thereon.

The method for producing an antireflection film of the present invention is a binder in which an intermediate layer containing a resin as a main component is formed on a transparent substrate film, and then ultrafine particles are dispersed on the intermediate layer. By coating a binder having a refractive index higher than that of the ultrafine particles and having a low surface tension so as to expose the surface of the ultrafine particles, the surface of the ultrafine particles was completely exposed and unevenness was formed. A method for producing an antireflection film having an antireflection film, which comprises forming an outermost layer in which air and ultrafine particles are mixed. By providing an intermediate layer between the base film and the antireflection film, the adhesion and strength can be improved.

In the method for producing an antireflection film, a transparent base film is provided with an intermediate layer in a semi-cured state, and a binder in which ultrafine particles are dispersed on the intermediate layer in the semi-cured state. By coating a binder having a refractive index higher than that of the fine particles and having a weak surface tension so as to expose the surface of the ultrafine particles, the surface of the ultrafine particles is completely exposed and unevenness is formed. A method for producing an antireflection film is characterized in that the outermost layer in which air and ultrafine particles are mixed is formed, and the intermediate layer in the semi-cured state is completely cured. By thus semi-curing the intermediate layer and then completely curing it, the antireflection film can be sufficiently adhered to the transparent substrate film.

The ultrafine particles contained in the antireflection film of the present invention are in a state of being densely packed in one layer in the coating film,
It is preferable that each ultrafine particle is in pinpoint contact with a minimum amount of binder.

In the present invention, "completely exposed" means a state in which the ultrafine particles are not covered with the binder on the surface of the antireflection film.

FIG. 1 shows a cross section of the antireflection film of the present invention. In FIG. 1, 1 is an air layer in contact with the antireflection film of the present invention, 2 is an ultrafine particle / air mixed layer in which air is mixed with ultrafine particles whose surface is exposed to the air, and 3 is substantially 2 is an ultrafine particle layer composed of only ultrafine particles, and 4 is an ultrafine particle / binder mixed layer in which ultrafine particles and a binder are mixed. The antireflection film is attached to the base material to prevent reflection.

The refractive index of the air layer 1 is 1, and the refractive index of the ultrafine particle layer 3 consisting essentially of ultrafine particles is higher than the refractive index of the air layer 1. For example, MgF ₂ has a refractive index of 1.3.
8. Since SiO ₂ is 1.46, the refractive index of the ultrafine particle / air mixed layer 2 located between the air layer 1 and the ultrafine particle layer 3 is equal to that of the air layer 1 and that of the ultrafine particle layer 3. It will be located between the rates. Further, since the refractive index of the binder is set higher than that of the ultrafine particles, the refractive index of the ultrafine particle / binder mixed layer 4 following the ultrafine particle layer 3 becomes higher than that of the ultrafine particle layer 3. . This ultrafine particle / binder mixed layer 4 is the side to be joined to the base material to be antireflection.

Therefore, the refractive index of the antireflection film of the present invention gradually increases in the order of the air layer 1, the ultrafine particle / air mixed layer 2, the ultrafine particle layer 3, and the ultrafine particle / binder mixed layer 4, which is advantageous. It is possible to prevent light reflection.

In the antireflection film of the present invention, a film having a refractive index lower than that of the ultrafine particles may be further formed on the outermost surface layer of the antireflection film where the ultrafine particles are exposed. Such a film can be formed by a vapor phase method such as vapor deposition or plasma CVD.

The binder used in the antireflection film of the present invention must be a resin having a low surface tension that allows the surface of the ultrafine particles to be exposed without being covered. Specifically, the surface tension is 10 to 30 dyn / cm,
Particularly preferably, those having 10 to 20 dyn / cm are used. The reason is that if the amount is out of this range, the binder will cover the surface of the ultrafine particles, and the refractive index in the antireflection film cannot be gradually increased stepwise as described above, and an effective antireflection effect is obtained. Because I can't.

As such a binder, an ionizing radiation curable resin, a thermoplastic resin, or a thermosetting resin is used, and examples thereof include the following. Thermoplastic resins or thermosetting resins such as fluororesins, acrylic resins, polyurethane resins, melamine resins, epoxy resins, polyester resins, polyamide resins, alkyd resins, vinyl chloride resins, and silicone resins are used. Examples of the fluororesin include 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 1H, 1H, 5H-octafluoropentyl acrylate, 1H, 1H, 2H, 2H-heptadecafluorodecyl acrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 1H, 1H, 5H-octafluoropentyl methacrylate, 1H, 1H, 2H, 2
H-heptadecafluorodecyl methacrylate, poly (perfluoroisobutyl acrylate), poly (pentadecafluorooctyl acrylate), poly (1-chlorodifluoromethyl-tetrafluoroethyl acrylate), poly (heptafluorobutyl acrylate),
Poly (1-trifluoromethyl-tetrafluoroethyl acrylate), poly [2- (2-trifluoromethyl-tetrafluoroethoxy) ethyl acrylate], poly [5- (1-trifluoromethyl-tetrafluoroethoxy) pentyl acrylate ], Poly [11- (1-
Trifluoromethyl-tetrafluoroethoxy) undecyl acrylate], poly [(1-trifluoromethyl) 2,2,2-trifluoroethyl acrylate],
Poly (perfluoro-tert-butylmethacrylate), poly (1-chlorodifluoromethyl-tetrafluoroethylmethacrylate), poly (pentadecafluorooctylmethacrylate), poly (tetrafluoropropylmethacrylate), poly (1-trifluoromethyl-) Tetrafluoroethyl methacrylate), poly (1
-Trifluoromethyl-2,2,2-trifluoroethyl methacrylate), poly (vinylidene chloride),
Poly (vinylidene fluoride), poly (styrene-c
o-tetrafluoropropyl methacrylate), poly (oxy-1-pentafluorophenyl-1-trifluoromethyltrifluoroethoxymethylethylene), poly (oxy-1-phenyl-1-trifluoromethyltrifluoroethoxymethylethylene), Poly (oxy-
3-trifluoromethylphenoxymethylethylene),
Poly [oxy-1- (3-trifluoromethyl) phenyl-1-trifluoromethyltrifluoroethoxymethylethylene], poly [(1-trifluoromethyltetrafluoroethoxymethyl) ethylene-co-maleic anhydride] , Poly [1- (1-trifluoromethyltetrafluoroethoxymethyl) -1-methylethylene-co-maleic anhydride].

The amount ratio of the ultrafine particles and the binder, which is an amount suitable for exposing the surface of the ultrafine particles without covering, is as follows: ultrafine particles / binder = 10/0 to 1/1 (particularly preferably 4/1 to
2/1). In addition, since the dispersibility of the ultrafine particles in the binder is improved by mixing the binder and the ultrafine particles in this way, it becomes possible to form a coating film in which the ultrafine particles are uniformly distributed.

Further, in the case of applying only ultrafine particles without any binder, a coating film is formed by applying a dispersion liquid of ultrafine particles. In this case, since no binder is present, the film becomes a state in which the ultrafine particles are in pinpoint contact with each other, and the surface thereof also has irregularities in which the ultrafine particles are arranged.

The ultrafine particles having a low refractive index used in the present invention include MgF ₂ (refractive index 1.38), SiO ₂ (refractive index 1.46), AlF ₃ (refractive index 1.33 to 1.3).
9), CaF ₂ (refractive index 1.44), LiF (refractive index from 1.36 to 1.37), NaF (index of refraction from 1.32 to 1.
34), and ultrafine particles such as ThF ₄ (refractive index 1.45 to 1.5). The particle size of these ultrafine particles is 1 to
100 nm is preferable, and especially for MgF ₂ , the particle size is 10 n.
Those around m are preferred. SiO ₂ has a particle size of 10 to 10
0 nm is preferred.

The reason for using such a particle size is that with MgF ₂ , if it is less than 1 nm, the production is difficult and the cost is high.
This is because if it is more than 00 nm, turbidity increases and transparency decreases. Further, if the thickness of SiO ₂ is less than 10 nm, the production becomes difficult and the cost becomes high, and the adhesiveness and the dispersion stability are deteriorated.
This is because if it is more than 00 nm, turbidity increases and transparency decreases.

Examples of the high refractive index ultrafine particles used in the antireflection film of the present invention include ZnO (refractive index 1.90), TiO ₂ (refractive index 2.3 to 2.7), Ce.
O ₂ (refractive index 1.95), Sb ₂ O ₅ (refractive index 1.7
1), SnO ₂ , ITO (refractive index 1.95), Y ₂ O ₃
(Refractive index 1.87), La ₂ O ₃ (refractive index 1.95),
ZrO ₂ (refractive index 2.05), Al ₂ O ₃ (refractive index 1.
63) and the like. Of these ultrafine particles having a high refractive index, it is preferable to use ZnO, TiO ₂ , CeO ₂ or the like because the antireflection film of the present invention is further provided with a UV shielding effect. Further, by using SnO ₂ or ITO doped with antimony, the electron conductivity is improved, and the adhesion of dust due to the antistatic effect is prevented,
Alternatively, when the antireflection film of the present invention is used for a CRT, an electromagnetic wave shielding effect can be obtained, which is preferable. The particle diameter of the high refractive index ultrafine particles is preferably 400 nm or less in order to make the hard coat layer transparent.

When the above-mentioned high refractive index ultrafine particles are used for the antireflection film, the refractive index of the layer containing the high refractive index ultrafine particles is further provided on the high refractive index ultrafine particle containing layer. It is necessary to enhance the antireflection effect by forming a layer having a lower refractive index.

The low refractive index material used for forming the low refractive index layer may be any material as long as it satisfies the above conditions, and an inorganic material or an organic material can be used.

As the low refractive index inorganic material, for example, Li
F (refractive index 1.4), MgF ₂ (refractive index 1.4), 3N
aF · AlF ₃ (refractive index 1.4), AlF ₃ (refractive index 1.4), Na ₃ AlF ₆ (cryolite, refractive index 1.3)
8), SiO _x (x: 1.50 ≦ x ≦ 2.00) (refractive index 1.35 to 1.48), and other inorganic materials are used.

A film formed of an inorganic material having a low refractive index has a high hardness, and in particular, SiO _x (x is 1.
50 ≦ x ≦ 4.00, preferably 1.70 ≦ x ≦ 2.2
It is preferable that the film of (0) formed has good hardness and excellent adhesion to the hard coat layer and can reduce heat damage to the transparent substrate film as compared with other vapor phase methods.

As the low refractive index organic material, an organic substance such as a polymer having a fluorine atom introduced therein is preferable because the refractive index thereof is as low as 1.45 or less. Polyvinylidene fluoride (refractive index 1.40) is mentioned as a resin that can be used as a solvent because it is easy to handle. When this polyvinylidene fluoride is used as the low-refractive-index organic material, the refractive index of the low-refractive-index layer is approximately 1.40, but trifluorofluoride is used to further reduce the refractive index of the low-refractive-index layer. A low refractive index acrylate such as ethyl acrylate (refractive index 1.32) may be added in an amount of 10 to 300 parts by weight, preferably 100 to 200 parts by weight.

Since this trifluoroethyl acrylate is a monofunctional type and therefore the film strength of the low refractive index layer is not sufficient, a polyfunctional acrylate such as, for example,
It is desirable to add dipentaerythritol hexaacrylate (abbreviation: DPHA, tetrafunctional type) which is an ionizing radiation curable resin. The film strength of DPHA increases as the amount of addition increases, but from the viewpoint of reducing the refractive index of the low refractive index layer, the amount of addition is preferably small, and is 1 to 50 parts by weight, preferably 5 to 20 parts by weight. Is recommended.

The low-refractive index layer is formed by vapor deposition, sputtering, ion plating or plasma CVD on the layer containing the high-refractive index fine particles with an inorganic material having a lower refractive index.
Forming a single layer or a multilayer by a vapor phase method such as, or by applying a low refractive index resin composition containing a low refractive index inorganic material or a low refractive index inorganic material, a single layer or a multilayer It can be performed by forming a coating film.

The antireflection film of the present invention is formed by mixing the mixture of the ultrafine particles and the binder with an organic solvent as a dispersion medium to prepare a coating liquid for forming an antireflection film, and applying the coating liquid. To do. Such organic solvents include, for example, alcohols, ketones, esters, halogenated hydrocarbons, ethers and the like, and particularly alcohols such as methyl alcohol, ethyl alcohol, butyl alcohol, n-propyl alcohol and isopropyl alcohol are preferably used. To be

The surface of the ultrafine particles used in the present invention may be modified. This modification treatment improves dispersibility in various solvents and binders,
It also improves the adhesion between layers. The surface modification method for such purpose includes treatment with a coupling agent, Si
Coating with O ₂ , coating with resin, grafting of polymer or oligomer chains, combination of coating with SiO ₂ and grafting of polymer chains, hybridization by monomer polymerization in fine particle dispersion, surface with hybridase Modification (solid phase reaction) and the like can be mentioned.

In the present invention, functional ultrafine particles having a particle size smaller than that of the ultrafine particles may be added to the mixture of the ultrafine particles and the binder. Examples of the functional ultrafine particles include conductive ultrafine particles. The mixing ratio of ultrafine particles for antireflection and this functional ultrafine particle is 1 /
It is preferably 9 to 9/1, particularly preferably 3 /
7 to 7/3.

The base material to which the antireflection film of the present invention is applied is
Resin, glass, metal, ceramics or the like can be applied as a material, and can be applied to a film, a sheet, a plate or a three-dimensional structure. As a resin substrate, triacetyl cellulose, diacetyl cellulose, acetate butyrate cellulose,
Examples thereof include polyether sulfone, polyacrylic resin, polyurethane resin, polyester, polycarbonate, polysulfone, polyether, trimethylpentene, polyether ketone, and (meth) acrylonitrile. When the ultrafine particles are MgF ₂ having a low refractive index, a triacetyl cellulose film, which is a protective film for a polarizing element, has a refractive index of 1.5 or less, which is suitable for the base material. When the ultrafine particles are SiO ₂ having a relatively low refractive index, the base material can be applied to polyethylene terephthalate, acrylic, etc. having a refractive index of around 1.6.

The coating solution for forming the antireflection film in the present invention is applied to various substrates by a coating method such as curtain flow coating, dip coating, spin coating, roll coating or spray coating. Coating film is formed.

The antireflection film of the present invention may be attached to a transparent substrate film via an intermediate layer to form an antireflection film. The intermediate layer may have various functionalities, for example, a hard coat layer, an antistatic layer, a moisture proof layer and the like.

When the intermediate layer is a hard coat layer, the resin forming the hard coat layer is a resin mainly curable by ultraviolet rays or electron beams, that is, an ionizing radiation curable resin alone or an ionizing radiation curable resin. A type resin in which an adhesive resin is mixed, an ionizing radiation curable resin in which a thermosetting resin is mixed, and a solid-state reaction type ionizing radiation curable resin are used.

Ionizing radiation-curable resin: The ionizing radiation-curable resin used in the resins forming the hard coat layer preferably has an acrylate-based functional group, for example, a polyester having a relatively low molecular weight. Resin, polyether resin, acrylic resin, epoxy resin,
Urethane resin, alkyd resin, spiro acetal resin, polybutadiene resin, polythiol polyene resin,
Oligomers or prepolymers such as (meth) acrylates of polyfunctional compounds such as polyhydric alcohols and ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N as reactive diluents
-Monofunctional and polyfunctional monomers such as vinylpyrrolidone, eg trimethylolpropane tri (meth)
Acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6
-Hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, etc. which contain a relatively large amount can be used.

Furthermore, in order to use the above ionizing radiation curable resin as an ultraviolet curable resin, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, tetramethyl are used as photopolymerization initiators in the resin. Thiuram monosulfide, thioxanthone, and n-butylamine, triethylamine, tri-n-butylphosphine and the like can be mixed and used as a photosensitizer. Particularly in the present invention, it is preferable to mix urethane acrylate as the oligomer and dipentaerythritol hexaacrylate as the monomer.

Resin having tackiness: The resin having tackiness mixed with the above-mentioned ionizing radiation-curable resin imparts viscosity to the ionizing radiation-curable resin, and includes a pressure-sensitive adhesive and an ionizing radiation-curable resin. It is preferable that the resin is formed from a mixture thereof, but it can be used as it is if the ionizing radiation-curable resin is not crosslinked in a liquid state and has an adhesive property. In particular, in order to keep the hardness of the coating film high, thermoplastic resins such as polymethyl methacrylate and polybutyl methacrylate can be preferably used.

The other resin may be one that has been used for a conventionally known adhesive tape or adhesive seal, for example,
Rubber-based resins such as polyisoprene rubber, polyisobutylene rubber, styrene-butadiene rubber, butadiene-acrylonitrile rubber, (meth) acrylic acid ester-based resin, polyvinyl ether-based resin, polyvinyl acetate-based resin, polyvinyl chloride / vinyl acetate copolymer-based Resin, polystyrene resin, polyamide resin, polychlorinated olefin resin,
Suitable tackifiers for polyvinyl butyral resin and the like, for example, rosin, dammar, polymerized rosin, partially hydrogenated rosin,
Ester rosin, polyterpenic resin, terpene modified product, petroleum resin, cyclopentadiene resin, phenol resin, coumarone-indene resin are appropriately added, and if necessary, a softening agent, a filler, an antiaging agent, etc. It was added.

The purpose of mixing the resin having tackiness with the ionizing radiation curable resin is to semi-cure the coating film and to impart tackiness. The mixing ratio of the resin having adhesiveness to the ionizing radiation curable resin is preferably 50 parts by weight or less with respect to 100 parts by weight of the ionizing radiation curable resin for the purpose of semi-curing the coating film. .

Thermosetting resin: The thermosetting resin mixed with the above-mentioned ionizing radiation-curable resin includes phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin. There are resins, epoxy resins, aminoalkyd resins, melamine / urea co-condensation resins, silicon resins, polysiloxane resins, etc., and if necessary, crosslinking agents, curing agents such as polymerization initiators, polymerization accelerators, etc. A solvent, a viscosity modifier, an extender pigment, etc. are added. Usually as the curing agent,
Isocyanates are often used in unsaturated polyester resins or polyurethane resins, and peroxides such as methyl ethyl ketone peroxide and radical initiators such as azobisisobutyronitrile are often used in unsaturated polyester resins. Furthermore, as the isocyanate as the curing agent, divalent or higher valent aliphatic or aromatic isocyanate can be used.

Solid Phase Reaction Ionizing Radiation Curable Resin: The solid phase reaction type ionizing radiation curable resin is solid at room temperature in the uncrosslinked state, and has thermoplasticity and solvent solubility, It is mainly composed of an ionizing radiation curable resin that gives a coating that is non-fluid (drying to the touch) even when touched by hand by coating and drying, and that is non-adhesive. is there. Specifically, for example, the following two types of resins (a) and (b) are exemplified. A similar resin is disclosed in JP-A-1-202492. Furthermore, the resins shown in (a) and (b) below can be mixed and used, and a radically polymerizable unsaturated monomer can be added thereto for use.
Reactive diluents, sensitizers and the like used in ordinary ionizing radiation curable resins are added to these resins. Further, a non-crosslinking thermoplastic resin may be added in order to impart flexibility to the cured resin product.

(A) A resin having a radically polymerizable unsaturated group in a polymer having a glass transition temperature of 0 to 250 ° C.

Specifically, it is a resin obtained by polymerizing or copolymerizing the monomers listed below and introducing a radical copolymerizable unsaturated group by the methods a) to d) described below.

Monomers having hydroxyl groups: For example, N-methylol (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy. Examples include propyl (meth) acrylate.

Monomers having a carboxyl group: For example, (meth) acrylic acid, (meth) acryloyloxyethyl monosuccinate and the like can be mentioned.

Monomer Having Epoxy Group: For example, glycidyl (meth) acrylate and the like.

Monomers having an aziridinyl group: 2-aziridinylethyl (meth) acrylate, allyl 2-aziridinylpropionate and the like.

Monomers having amino groups: (meth) acrylamide, diacetone (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and the like.

Monomers having sulfone groups: 2- (meth) acrylamido-2-methylpropanesulfonic acid and the like.

Monomer having isocyanate group: 2,
There are adducts of diisocyanate and a radical copolymer having active hydrogen, such as an adduct of 4-toluene diisocyanate and 2-hydroxyethyl (meth) acrylate in an amount of 1 mol to 1 mol.

Further, in order to adjust the glass transition temperature of the copolymer and the physical properties of the cured film, each of the above-listed monomers can be copolymerized with the following compounds. Examples of such a copolymerizable monomer include methyl (meth) acrylate and propyl (meth).
Examples thereof include acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, gt-butyl (meth) acrylate, isoamyl (meth) acrylate, cyclohexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.

By introducing a radically polymerizable unsaturated group into the resin obtained by polymerizing or copolymerizing each of the above-mentioned monomers by the following methods a) to d), an ultraviolet curable resin or An ionizing radiation curable resin such as an electron beam curable resin can be obtained.

A) In the case of a polymer or copolymer of a monomer having a hydroxyl group, a monomer having a carboxyl group such as (meth) acrylic acid is subjected to a condensation reaction.

B) In the case of a polymer or copolymer of a monomer having a carboxyl group or a sulfone group, the above-mentioned monomer having a hydroxyl group is subjected to a condensation reaction.

C) In the case of a polymer or copolymer of a monomer having an epoxy group, an isocyanate group or an aziridinyl group, the above-mentioned monomer having a hydroxyl group or a monomer having a carboxyl group is subjected to an addition reaction. .

D) In the case of a polymer or copolymer of a monomer having a hydroxyl group or a carboxyl group, a monomer having an epoxy group, a monomer having an aziridinyl group or a diisocyanate compound and a hydroxyl group-containing acrylate ester Addition reaction is performed with 1 mol of monomer to 1 mol of adduct.

In order to carry out the above reaction, it is desirable to add a trace amount of a polymerization inhibitor such as hydroquinone and to carry out it while sending dry air.

(B) A resin having a radical-polymerizable unsaturated group having a melting point of room temperature (20 ° C.) to 250 ° C.

Specific examples include stearyl acrylate, stearyl (meth) acrylate, triacrylic isocyanate, cyclohexanediol (meth) acrylate, spiroglycol diacrylate, and spiroglycol (meth) acrylate.

The ionizing radiation-curable resin used for the hard coat layer in the present invention generally has a refractive index of about 1.5, which is similar to that of glass, but higher than that of ultrafine particles and transparent. By making the refractive index higher than that of the base film, the antireflection effect can be enhanced and reflection at the interface between the hard coat layer and other layers can be prevented. The method for increasing the refractive index of the hard coat layer is to use a binder resin having a high refractive index in the hard coat layer, or to have a refractive index higher than that of the hard coat layer, for example, as described above. Or adding ultrafine particles to the hard coat layer,
Alternatively, these methods are used together.

The binder resin having a high refractive index includes
A resin containing an aromatic ring, a halogenated element other than F, for example, a resin containing Br, I, Cl, etc., a resin containing an atom such as S, N, P, etc. are mentioned, and at least one of these conditions is satisfied. It is desirable because the resin has a high refractive index.

Examples of the above resins include styrene resins such as polystyrene, polyethylene terephthalate, polyvinyl carbazole, and polycarbonate of bisphenol A.

Examples of the above resin include polyvinyl chloride,
Examples thereof include polytetrabromobisphenol A glycidyl ether.

Examples of the above resin include polybisphenol S glycidyl ether, polyvinyl pyridine and the like.

When ultrafine particles having a high refractive index as described above are added to the hard coat layer, the addition amount of the ultrafine particles is
The difference greatly depends on the refractive index of the resin used and the refractive index of the ultrafine particles used. For example, it is usually about 30 to 500 parts by weight with respect to 100 parts by weight of the resin. In this case, if too many ultrafine particles are added, the transparency and strength of the coating film will decrease, so these points must be taken into consideration.

Method for Curing Intermediate Layer Coating Film: In the present invention, a semi-cured layer is formed by making the intermediate layer applied on a substrate into a semi-cured state such as touch-drying or half-cure, and the semi-cured layer is formed thereon. An antireflection film is formed. The reason for semi-curing the intermediate layer in the present invention is that even if an antireflection film is formed on the completely cured intermediate layer, the adhesion between the layers is poor and defects such as peeling occur. This is because when the intermediate layer is dry to the touch or semi-cured by half-cure, the antireflection film is formed, and then the intermediate layer is completely cured, whereby the adhesion between both coating films is improved.

The semi-cured state in the present invention is classified as follows depending on the type of resin used.

(1) Solvent drying type semi-curing a. Solvent-drying semi-curing The coating film formed by applying a solvent to a normal ionizing radiation-curing resin and drying the solvent is a semi-cured state, and the ionizing radiation-curing resin is a curing reaction. Is not completed.

Since the above composition alone cannot maintain a sufficient viscosity, a solvent-drying thermoplastic resin is added to adjust the viscosity suitable for coating. When a coating film is formed using this resin composition, the solvent is released and diffused during drying, and the coating film is in a semi-cured state.

As the solvent-drying type thermoplastic resin to be added to the ionizing radiation-curable resin, those usually used are used. Especially, when polymethyl methacrylate or polybutyl methacrylate is used, the hardness of the coating film is high. Can be kept. Moreover, in this case, since the refractive index is close to that of the main ionizing radiation curable resin, the transparency of the coating film is not impaired,
It is advantageous in transparency. Further, as another example of the solvent-drying type thermoplastic resin, when a cellulosic polymer is added to an ionizing radiation-curable resin, when triacetyl cellulose is used as a transparent resin substrate, toluene, which is a non-soluble solvent of triacetyl cellulose, is used. Even if it is applied to the transparent resin substrate using, the adhesion between the transparent resin substrate and the coating resin can be improved. Moreover, since toluene does not dissolve triacetyl cellulose as a transparent resin substrate, it does not whiten the transparent resin substrate.

The mixing ratio of this resin composition is such that the addition amount of the thermoplastic resin is 50 parts by weight or less with respect to 100 parts by weight of the ionizing radiation curable resin. If the addition amount of the thermoplastic resin is more than this, the hardness of the upper coating film cannot be kept high,
Inferior scratch resistance.

B. Solid-state reaction-type ionizing radiation-curable semi-curing This semi-curing is a state of semi-curing by the solid-state reaction-type ionizing radiation-curing resin, which is solid at room temperature in the uncrosslinked state, and is thermoplastic and solvent. It refers to a state in which the resin has solubility, is non-fluid and non-tacky by appearance and by touching with coating and drying, and the curing reaction of the ionizing radiation curable resin is not completed.

(2) Half cure type semi-curing a. Ionizing radiation curable resin semi-crosslinking type semi-curing Applying using the ordinary ionizing radiation curable resin shown in the item of the hard coat layer, adjusting the irradiation conditions of ionizing radiation such as ultraviolet rays or electron beams to the coating film. A semi-cured state formed by carrying out semi-crosslinking.

B. Ionizing radiation curable resin / thermosetting resin blend type semi-curing Mixing a thermosetting resin with the ionizing radiation curable resin shown in the item of the hard coat layer, applying a resin composition, and applying heat to the coating film. It means a semi-cured state formed by the above.

The blending ratio of this resin composition is such that the addition amount of the thermosetting resin is 50 parts by weight or less with respect to 100 parts by weight of the ionizing radiation curing resin. The reason is that if the amount of the thermosetting resin added is more than this, the hardness of the coating film decreases.

C. Solvent-drying / half-cure composite semi-curing This is a state in which the solvent-drying semi-curing state (1) is further irradiated with ionizing radiation to be a semi-curing state. This semi-cured state is the same as the semi-cured state described in JP-A-1-20249.

Complete curing step: Complete curing of the coating film forming the intermediate layer in the present invention is carried out by irradiation with ionizing radiation. At the stage where the antireflection film is formed on the intermediate layer, the ionizing radiation-curable resin in the intermediate layer coating film contains an uncrosslinked component, so that the coating film is completely cured by irradiation with ionizing radiation. .

Irradiation device: The ionizing radiation curable resin used in the present invention can be cured by a usual method for curing an ionizing radiation curable resin, that is, an electron beam or an ultraviolet ray. For example, in the case of electron beam curing, Cockloft-Walton type, Van de Graaff type, resonance transformation type,
50-1000 emitted from various electron beam accelerators such as insulating core transformer type, linear type, dynamitron type, high frequency type
An electron beam or the like having an energy of KeV, preferably 100 to 300 KeV is used, and in the case of ultraviolet curing, ultraviolet rays emitted from light rays such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc and a metal halide lamp are used. Available.

Other layers: In the antireflection film of the present invention,
In addition to the layers described above, layers for imparting various functionalities can be additionally provided. For example, a primer layer or an adhesive layer may be provided on the transparent substrate film for the purpose of improving the adhesiveness with the transparent substrate film, or a plurality of hard coat layers may be provided to improve the hard performance. May be. As described above, the refractive index of the other layers provided between the transparent base film and the hard coat layer is preferably an intermediate value between the refractive index of the transparent base film and the refractive index of the hard coat layer.

As another method for forming the layer, the layer may be formed by directly or indirectly coating on the transparent substrate film as described above, or by forming the hard coat layer on the transparent substrate film by transfer. In this case, another layer may be applied and formed on the hard coat layer previously formed on the transfer film, and then transferred to the transparent substrate film.

An adhesive may be applied to the lower surface of the antireflection film of the present invention, and this antireflection film can be used by being attached to an object to be antireflection, for example, a polarizing element.

Polarizing plate and liquid crystal display device: By laminating the antireflection film of the present invention on a polarizing element,
A polarizing plate having improved antireflection property can be obtained. For this polarizing element, it is preferable to use a transparent substrate film such as a polyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetal film, an ethylene-vinyl acetate copolymer saponified film, which is dyed with iodine or a dye and stretched. it can. In laminating the transparent substrate film and the polarizing element, in order to increase the adhesiveness and to prevent static electricity, when the transparent substrate film is, for example, a triacetyl cellulose film,
The triacetyl cellulose film is saponified.
This saponification treatment may be performed before or after applying the hard coat to the triacetyl cellulose film.

FIG. 2 shows an example of a polarizing plate using the antireflection film of the present invention. In FIG. 2, 10 is an antireflection film of the present invention, which comprises an antireflection film 5, an intermediate layer 6 such as a hard coat layer, and a transparent substrate film (for example, triacetyl cellulose film) 7. The antireflection film 10 is laminated on the polarizing element 8, while the transparent substrate film 7 is laminated on the other surface of the polarizing element 8. Further, the antireflection film 10 of the present invention may be laminated on both surfaces of the polarizing element 8.

FIG. 3 shows an example of a liquid crystal display device using the antireflection film 10 of the present invention. On the liquid crystal display element 9, the polarizing plate shown in FIG. 2, that is, the transparent substrate film 7 /
A polarizing plate having a layer structure including a polarizing element 8 / antireflection film 10 (transparent substrate film 7 / intermediate layer 6 / antireflection film 5) is laminated, and the other surface of the liquid crystal display element 9 is transparent. A polarizing plate having a layered structure composed of base film 7 / polarizing element 8 / transparent base film 7 is laminated. In the STN type liquid crystal display device, a retardation plate is inserted between the liquid crystal display element 9 and the polarizing plate.

[0090]

【Example】

[Example 1] 50 parts by weight of polymethacrylic acid methacrylate as a thermoplastic resin was added to 100 parts by weight of an ionizing radiation curable resin (EXG: trade name: manufactured by Dainichiseika) consisting of a mixture of polyester acrylate and polyurethane acrylate. To prepare a coating composition. A bar coater was applied on the surface of a triacetyl cellulose film (FT-UV-80: trade name: manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm so that the film thickness was 7 μm (when dried). Applied. It was prepared by adding 50 parts by weight of magnesium fluoride sol (MFS-10P: product name: Nissan Chemical Industries) to 100 parts by weight of tetrafluoroacrylate (biscoat 4F: product name: Osaka Organic Chemical Industry). The coating composition was diluted with isopropanol and then applied using a bar coater so that the film thickness would be 0.12 μm (when dried). The coating film is dried to remove the solvent, and the electron beam accelerated at 175 KeV is irradiated with 5M.
The upper coating film and the lower coating film were completely cured at the same time by irradiation with rad energy.

The antireflection film obtained in Example 1 has a wavelength of 3
With light of 50 to 700 nm, the transmittance was improved by about 4% and the reflection was decreased.

Example 2 100 parts by weight of an ionizing radiation curable resin (EXG: trade name: manufactured by Dainichiseika Co., Ltd.) made of a mixture of polyester acrylate and polyurethane acrylate was added with 50 parts of polymethacrylic acid methacrylate as a thermoplastic resin. A coating composition was prepared by adding parts by weight. The lower coating film coating composition was applied onto the surface of a 100 μm thick polyester film (HP-7: trade name: Teijin) using a bar coater so that the film thickness would be 10 μm (when dried). A coating composition prepared by adding 100 parts by weight of colloidal silica (Snowtex: product name: Nissan Chemical Industries, Ltd.) to 20 parts by weight of tetrafluoroacrylate (biscoat 4F: product name: Osaka Organic Chemicals). Was diluted with methyl ethyl ketone to give a film thickness of 0.12μ
The coating was carried out using a bar coater so that it would be m (when dried). The coating film is dried to remove the solvent, and further 175 Ke
The upper layer coating film and the lower layer coating film were completely cured at the same time by irradiating the electron beam accelerated with V with the energy of 5 Mrad.

The antireflection film obtained in Example 2 has a wavelength of 3
With light of 50 to 700 nm, the transmittance was improved by about 6% and the reflection was decreased.

[0094]

EFFECTS OF THE INVENTION The antireflection film of the present invention gradually increases its refractive index gradually and gradually from the outermost surface thereof toward the substrate to which the antireflection film is attached. It is possible to effectively prevent reflection of light from the outside.

The method for producing an antireflection film for forming an antireflection film of the present invention is one coat treatment in which the refractive index of the antireflection film is increased from the outermost surface thereof toward the substrate to which the antireflection film is attached. Since it can be gradually increased in a stepwise manner, an effective antireflection film and antireflection film can be produced by a simple production method.

Since the antireflection film of the present invention is formed on the semi-cured intermediate layer and the intermediate layer is completely cured, it has sufficient adhesion to the substrate. Moreover, since the intermediate layer can be a hard coat layer, a durable antireflection film can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an antireflection film of the present invention.

FIG. 2 shows an example of a polarizing plate using the antireflection film of the present invention.

FIG. 3 shows an example of a liquid crystal display device using the antireflection film of the present invention.

[Explanation of symbols]

 1 Air Layer 2 Ultrafine Particle / Air Mixed Layer 3 Ultrafine Particle Layer 4 Ultrafine Particle / Binder Mixed Layer 5 Antireflection Film 6 Intermediate Layer 7 Transparent Substrate Film 8 Polarizing Element 9 Liquid Crystal Display Element 10 Antireflection Film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number of the agency FI technical display location B32B 27/00 N 8413-4F (72) Inventor Norinaga Nakamura 1-chome, Tanikaga-cho, Shinjuku-ku, Tokyo 1-1-1 Dai Nippon Printing Co., Ltd. (72) Inventor, Motohiro Oka 1-1-1 Ichigayaka-cho, Shinjuku-ku, Tokyo Dai-ni Printing Co., Ltd.

Claims (20)

[Claims] (1) An outermost layer portion in which air and ultrafine particles are mixed, in which the ultrafine particles are completely exposed to form an uneven surface, and a portion consisting of the ultrafine particles following the outermost layer. An antireflection film, and (2) the refractive index of the ultrafine particles is equal to or smaller than the refractive index of the base film to which the antireflection film is applied, and (3) its reflection The antireflection film is characterized in that the refractive index thereof is gradually increased from the outermost layer to the lower part thereof. 2. (1) A portion of the outermost layer in which the air and the ultrafine particles are mixed, in which the surface of the ultrafine particles is completely exposed to form an uneven surface having substantially no binder film, and the uppermost surface layer continues. An antireflection film mainly composed of a part composed of ultrafine particles, and a part composed of a part consisting of the ultrafine particles and a binder following the part mainly composed of the ultrafine particles, and (2) the binder has a refractive index of the ultrafine particles Also has a large refractive index and is smaller than the refractive index of the substrate film to which the antireflection film is applied. (3) The antireflection film has its refractive index gradually increasing from the outermost layer to the lower part. The antireflection film is characterized in that 3. An antireflection film, comprising a film having a refractive index lower than that of ultrafine particles on the outermost layer of the antireflection film according to claim 1. 4. The antireflection film according to claim 3, wherein the film having a refractive index lower than that of the ultrafine particles is formed by a vapor phase method. 5. The antireflection film according to claim 2, 3 or 4, wherein the binder has a low surface tension such that the surface of the ultrafine particles is completely exposed. 6. The antireflection film according to claim 5, wherein the binder is a fluororesin. 7. The antireflection film according to claim 1, wherein the ultrafine particles are an inorganic material. 8. The antireflection film according to claim 7, wherein the ultrafine particles are MgF ₂ . 9. The antireflection film according to claim 7, wherein the ultrafine particles are SiO ₂ . 10. The antireflection film according to claim 1, wherein the surface of the ultrafine particles is modified. 11. The method according to claim 1, 2, 3, 4, 5, 6, 7,
An antireflection film, wherein the antireflection film described in 8, 9, or 10 is laminated on a transparent substrate film. 12. The method according to claim 1, 2, 3, 4, 5, 6, 7,
An antireflection film, wherein the antireflection film described in 8, 9, or 10 is laminated on a transparent substrate film via an intermediate layer. 13. The antireflection film according to claim 12, wherein the intermediate layer is a hard coat layer. 14. The antireflection film according to claim 11, 12 or 13, comprising an adhesive layer, a primer layer and / or a hard coat layer on the side of the transparent substrate film on which the antireflection film is formed. An antireflection film having another layer formed thereon. 15. An antireflection film having a pressure-sensitive adhesive layer formed on the back surface of the antireflection film according to claim 11, 12, 13, or 14. 16. A transparent base material film is coated with a dispersion liquid of ultrafine particles, whereby a portion where air and ultrafine particles having irregularities due to the ultrafine particles are formed on the outermost layer, and a portion below the portion are formed. Is a method for producing an antireflection film, which comprises forming an antireflection film having a portion composed of ultrafine particles. 17. A binder in which ultrafine particles are dispersed, which has a refractive index higher than that of the ultrafine particles,
Further, by coating a transparent base material film with a binder having a weak surface tension so as to completely expose the surface of the ultrafine particles, the surface of the ultrafine particles is completely exposed and the air and the ultrafine particles are formed. A method for producing an antireflection film having an antireflection film, the method comprising forming an outermost layer containing a mixture of: 18. (1) An intermediate layer containing a resin as a main component is formed on a transparent substrate film, and (2) a binder in which ultrafine particles are dispersed on the intermediate layer. By coating a binder having a refractive index higher than that of the ultrafine particles and having a low surface tension so as to expose the surface of the ultrafine particles, the surface of the ultrafine particles is completely exposed and the air and the superfine particles are formed. A method for producing an antireflection film having an antireflection film, comprising forming an outermost layer in which fine particles are mixed. 19. A semi-cured intermediate layer containing a resin as a main component is provided on a transparent substrate film, and (2) a binder in which ultrafine particles are dispersed on the semi-cured intermediate layer. By coating a binder having a refractive index higher than that of the ultrafine particles and having a low surface tension so as to expose the surface of the ultrafine particles, the surface of the ultrafine particles is completely exposed and uneven. Forming an outermost layer in which air and ultrafine particles are mixed, and (3) producing an antireflection film having an antireflection film, wherein the semi-cured intermediate layer is completely cured. Method. 20. The method for producing an antireflection film having an antireflection film according to claim 18, wherein the intermediate layer is a hard coat layer.