JP5426852B2 - Antireflection film - Google Patents

Description

  The present invention relates to an antireflection film applied to a display screen surface of a display (CRT display, plasma display, liquid crystal display, projection display, EL display, etc.), a building material surface such as a window or a show window.

  Conventionally, in an antireflection film in which a hard coat layer and a low refractive index layer are sequentially provided on a base film such as a polyester film, the hard coat layer generally has a high hardness and a high refractive index. The reflected light is reduced by the interference effect (see, for example, Patent Document 1). For this reason, the refractive index of the hard coat layer or the low refractive index layer is adjusted to an optimum value so that the reflectance is minimized. In the case of the hard coat layer, theoretically, when the refractive index is a square value of the low refractive index layer, the lowest reflection can be achieved. At this time, if there is a refractive index difference between the hard coat layer and the base film, the reflected light at the base film / hard coat layer interface increases, and the reflected light at the low refractive index layer / hard coat layer interface Multiple interference becomes significant. As a result, there has been a problem that the reflectance is increased.

In addition, when a colored component layer such as a color correction layer (for example, a neon cut layer for plasma display) is provided on the back surface of the antireflection film to make a composite, the reflection characteristics are greatly affected by the component layer. There was a problem that the minimum reflectance of a single unit was not reflected.
JP-A-9-222504

  The present invention has been made in view of the above points, and in an antireflection film formed by providing a hard coat layer and a low refractive index layer in this order on the surface of a polyester film, the polyester film / hard coat layer, hard coat Low reflection by controlling the optical film thickness of the hard coat layer and designing it to show the minimum reflectance at the target wavelength when there is multiple interference between the interface reflected light of the layer / low refractive index layer An object of the present invention is to provide an antireflection film that can be formed into a film.

In the antireflection film according to claim 1 of the present invention, a hard coat layer 2 and a low refractive index layer 3 are provided in this order on one surface of the polyester film 1, and either a dye or a pigment is provided on the other surface of the polyester film 1. It is an antireflection film formed by providing an absorption layer 4 containing one or both, and the maximum absorption wavelength λ _max of the absorption layer 4 is represented by an expression of 550 (nm) ≦ λ _max ≦ 650 (nm). When the refractive index (n ₂ ) of the hard coat layer 2 is larger than the refractive index (n ₁ ) of the polyester film 1, the optical film thickness (n ₂ d ₂ ) of the hard coat layer 2 is within the range. When the refractive index (n ₂ ) of the hard coat layer 2 is smaller than the refractive index (n ₁ ) of the polyester film 1 within the range represented by the following formula (1), the optical film of the hard coat layer 2 Thickness (n ₂ d ₂₎ is Ri range near represented by the following equation (2), and the minimum value is the reflectance of the formed antireflection layer in three layers of polyester film 1 and the hard coat layer 2 and the low-refractive index layer 3 wavelengths of is characterized in der Rukoto the range of 550nm or more 650nm or less.
(1) n ₂ d ₂ = (490 + 300 × m) ± 50 (nm)
(2) n ₂ d ₂ = (640 + 300 × m) ± 50 (nm)
(However, d ₂ (nm) is the physical film thickness of the hard coat layer 2, n ₂ d ₂ <4000 (nm), and m is a positive integer.)
The invention according to claim 2 is characterized in that, in claim 1, the refractive index (n ₂ ) of the hard coat layer 2 is 1.50 to 1.90.

  According to a third aspect of the present invention, in the first or second aspect, at least one oxide selected from titanium, aluminum, cerium, yttrium, zirconium, niobium, and antimony is contained in the hard coat layer 2 as high refractive index particles. It is characterized by being.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the hard coat layer 2 has an antistatic property.

  According to a fifth aspect of the present invention, in the hard coat layer 2 according to any one of the first to fourth aspects, at least one oxide selected from indium, zinc, tin, and antimony is contained in the hard coat layer 2 as conductive nanoparticles. It is characterized by this.

The invention according to a sixth aspect is characterized in that, in any one of the first to fifth aspects, the sheet resistance of the hard coat layer 2 is 10 ¹⁵ Ω / □ or less.

The invention according to claim 7 is characterized in that, in any one of claims 1 to 6, the refractive index (n ₃ ) of the low refractive index layer 3 is 1.30 to 1.45. .

  The invention according to claim 8 is characterized in that, in claim 7, an antifouling layer 5 is provided on the surface of the low refractive index layer 3.

  According to the antireflection film of the present invention, the optical film of the hard coat layer is present when there is multiple interference between the interface reflected lights of the polyester film / hard coat layer and hard coat layer / low refractive index layer. By designing the thickness to be controlled and exhibit the minimum reflectance at the target wavelength, an increase in reflectance due to multiple interference can be suppressed and the reflection can be reduced.

  According to the invention of claim 2, by setting the refractive index of the hard coat layer in a certain range, the interference effect with the reflected light on the surface of the low refractive index layer is sufficiently exhibited, and the antireflection film The reflectance can be reduced.

  According to the invention of claim 3, the refractive index of the hard coat layer can be increased, the reflection interference unevenness due to the hard coat layer can be reduced, the appearance characteristics are excellent, and the surface of the hard coat layer is low. When the refractive index layer is provided, high antireflection performance can be obtained.

  According to the fourth aspect of the invention, the hard coat layer can be prevented from being charged by static electricity or the like, and the dust can be made difficult to adhere.

  According to the invention which concerns on Claim 5, electroconductivity can be provided to a hard-coat layer with an electroconductive nanoparticle, and the hard-coat layer which has antistatic property can be provided easily.

  According to the invention which concerns on Claim 6, the antistatic property of a hard-coat layer can be improved.

  According to the seventh aspect of the present invention, the reflection of light can be further reduced by the low refractive index layer having a refractive index smaller than that of the hard coat layer, and the antireflection performance can be further enhanced.

  According to the eighth aspect of the present invention, it is possible to reduce contamination due to adhesion of fingerprints and improve the removability thereof.

  Embodiments of the present invention will be described below.

  FIG. 1 is a sectional view showing an example of an antireflection film according to the present invention. In this antireflection film, the polyester film 1 is used as a transparent substrate. A hard coat layer 2 and a low refractive index layer 3 are provided in this order on one surface of the polyester film 1. Further, an absorption layer 4 (color correction layer) is provided on the other surface of the polyester film 1. The absorbing layer 4 contains one or both of a dye and a pigment.

  FIG. 2 is a cross-sectional view showing another example of the antireflection film according to the present invention. As in FIG. 1, this antireflection film has a hard coat layer 2 and a low refractive index layer 3 provided on one surface of a polyester film 1, and an antifouling layer 5 provided on the surface of the low refractive index layer 3. Yes. Moreover, the absorption layer 4 is provided in the other surface of the polyester film 1 similarly to FIG.

  The polyester film 1 used in the present invention includes, as polyester, for example, an aromatic dicarboxylic acid component such as terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 4,4′-diphenyldicarboxylic acid, and, for example, ethylene glycol, Aromatic polyesters composed of glycol components such as 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol and the like are preferable, and in particular, polyethylene terephthalate, polyethylene-2,6-naphthalene dicarboxyl. Rate is preferred. Further, it may be a copolyester such as a plurality of components exemplified above.

  In order to improve the roll-up property of the film at the time of film formation, the transportability of the film when coating the hard coat layer 2 or the pressure-sensitive adhesive, etc. on the polyester film 1, as necessary, as a lubricant Organic or inorganic fine particles can be contained. Examples of such fine particles include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, crosslinked acrylic resin fine particles, crosslinked polystyrene resin fine particles, urea resin fine particles, melamine resin fine particles, and crosslinked silicone resin fine particles. In addition to the fine particles, a colorant, an antistatic agent, an ultraviolet absorber, an antioxidant, a lubricant, a catalyst, other resins, and the like can be optionally contained as long as the transparency is not impaired.

  The polyester film 1 in the present invention has a haze of 3% or less, preferably 1.5% or less. If the haze exceeds 3%, the visibility may be impaired in various display applications, which may not be suitable for optical applications. From this viewpoint, in order to improve blocking resistance in a roll state, slipperiness, and adhesion to the hard coat layer 2 while maintaining high transparency with a haze of 3% or less, easy adhesion on the nanometer order A polyester film 1 coated with a layer (not shown) is generally used conventionally.

  It is preferable that the polyester film 1 with an easily bonding layer controls the film thickness of an easily bonding layer to 5 nm or more and 80 nm or less. When the thickness is less than 5 nm, the easy-adhesive material for forming the easy-adhesive layer cannot be uniformly coated on the surface of the polyester film 1, and stable adhesion between the polyester film 1 and the hard coat layer 2 is ensured. May become difficult. On the other hand, when the thickness exceeds 80 nm, reflection at the easy-adhesion layer increases, and problems such as an increase in reflectivity as an antireflection film and deterioration in interference unevenness occur. In order to raise the reflectance of the polyester film 1 with an easily bonding layer, it is preferable to make the refractive index of an easily bonding layer into 1.50-1.80. If it is less than 1.50 or exceeds 1.80, the difference between the refractive index of the hard coat layer 2 and the polyester film 1 becomes large, and problems such as an increase in reflectivity as an antireflection film and deterioration in interference unevenness occur.

  Moreover, the thickness of the polyester film 1 used by this invention is although it does not specifically limit, 50-200 micrometers is preferable.

  In the present invention, the hard coat layer 2 is a coating having a hardness higher than that of the polyester film 1 which is a transparent plastic substrate, improves the hardness of the surface of the polyester film 1, and scratches caused by scratching with a load such as a pencil. It also prevents the occurrence of cracks in the low refractive index layer 3 due to bending of the polyester film 1 and improves the mechanical strength of the antireflection film.

  In the present invention, the pencil hardness of the hard coat layer 2 is preferably H or higher, more preferably 2H or higher. In order to improve the hardness of the hard coat layer 2, a reactive curable resin, that is, thermosetting is used. The hard coat layer 2 is preferably formed using at least one of a mold resin and an ionizing radiation curable resin as a hard coat material (composition for forming the hard coat layer 2).

  As the thermosetting resin, phenol resin, urea resin, diallyl phthalate resin, melamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, silicon resin, polysiloxane resin, etc. can be used. A crosslinking agent, a polymerization initiator, a curing agent, a curing accelerator, and a solvent can be added to these thermosetting resins as necessary. When the hard coat layer 2 is formed using a thermosetting resin, it is preferable that the thermosetting resin is applied to the surface of the polyester film 1 and then dried and cured by heating.

  The ionizing radiation curable resin preferably has an acrylate functional group, for example, a relatively low molecular weight polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, spiro resin. Acetal resin, polybutadiene resin, polythiol polyene resin, oligomers such as (meth) acrylates of polyfunctional compounds such as polyhydric alcohol, prepolymers, and reactive diluents such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, Monofunctional monomers such as methylstyrene and N-vinylpyrrolidone, as well as polyfunctional monomers such as 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. Can be used. Furthermore, in order to make the ionizing radiation curable resin into an ultraviolet curable resin, it is preferable to incorporate a photopolymerization initiator therein. Examples of the photopolymerization initiator include acetophenones, benzophenones, α-amyloxime esters, thioxanthones, and the like. In addition to the photopolymerization initiator, a photosensitizer may be used. Examples of the photosensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, and thioxanthone. When the hard coat layer 2 is formed using an ultraviolet curable resin that undergoes a photopolymerization reaction, the ultraviolet curable resin is preferably applied to the surface of the polyester film 1 and dried, and then cured by ultraviolet irradiation.

The antireflection film according to the present invention is formed so as to satisfy the following conditions. That is, when the refractive index (n ₂ ) of the hard coat layer 2 is larger than the refractive index (n ₁ ) of the polyester film 1, the optical film thickness (n ₂ d ₂ ) of the hard coat layer 2 is the following (1). When the refractive index (n ₂ ) of the hard coat layer 2 is smaller than the refractive index (n ₁ ) of the polyester film 1 within the range represented by the formula, the optical film thickness (n ₂ ) of the hard coat layer ₂ d ₂ ) is within the range represented by the following formula (2).
(1) n ₂ d ₂ = (490 + 300 × m) ± 50 (nm)
(2) n ₂ d ₂ = (640 + 300 × m) ± 50 (nm)
(However, d ₂ (nm) is the physical film thickness of the hard coat layer 2, n ₂ d ₂ <4000 (nm), and m is a positive integer. It is particularly preferable that m = 1 to 5.)
Refractive index of the polyester film 1 (n ₁₎ and the refractive index of the hard coat layer 2 if (n ₂₎ is different, a polyester film 1 / reflected light at the interface of the hard coat layer 2 and the hard coat layer 2 / low refractive index layer Multiple interference occurs between the reflected light at the interface 3 and the reflectance changes in a trigonometric manner with respect to the wavelength of the light. At this time, the reflection spectrum also changes depending on the optical film thickness (n ₂ d ₂ ) of the hard coat layer 2, and the wavelength at which the reflectance is minimized changes. On the other hand, the reflectance of the absorption layer 4 alone is minimum at the absorption maximum wavelength. When the wavelength at which the reflectance of the antireflection layer composed of the polyester film 1, the hard coat layer 2, and the low refractive index layer 3 becomes the minimum value matches the absorption wavelength of the absorption layer 4, the entire minimum The reflectance is the smallest. When the optical film thickness (n ₂ d ₂ ) of the hard coat layer 2 is within the range represented by the above formula (1) or (2), the absorption wavelength and the wavelength taken by the minimum reflectance of the antireflection layer are: As a result, the minimum reflectance is reduced.

  As described above, according to the antireflection film satisfying the above-described conditions, even if there is multiple interference between the interfacial reflected light of the polyester film 1 / hard coat layer 2 and hard coat layer 2 / low refractive index layer 3. It is possible to reduce the reflection.

Further, when the refractive index of the hard coat layer 2 _{(n 2)} and the low-refractive index layer 3 the refractive index of the _{(n 3)} is satisfying _n 2 _{= (n} ^{3) 2} of the formula, the surface reflection of the hard coat layer 2 The effect that the light and the surface reflection light of the low refractive index layer 3 interfere and cancel each other is maximized, and the reflection of the antireflection layer composed of the polyester film 1, the hard coat layer 2, and the low refractive index layer 3 is reflected. The rate can be the lowest. Therefore, practically, the refractive index (n ₂ ) of the hard coat layer 2 is preferably 1.50 to 1.90 for such reasons. Thus, by setting the refractive index of the hard coat layer 2 in a certain range, the interference effect with the reflected light on the surface of the low refractive index layer 3 is sufficiently developed, and the reflectance of the antireflection film is increased. It can be reduced. Moreover, sufficient intensity | strength will be acquired if the film thickness of the hard-coat layer 2 is 1-2 micrometers or more. The refractive index of the polyester film 1 _{(n 1)} is about 1.50 to 1.75, it is preferable to reduce the practical reflectance is 1.60 or more.

The refractive index (n ₂ ) of the hard coat layer 2 is usually about 1.49 to 1.52, but in the present invention, the antireflective performance is increased by adding high refractive index particles to the hard coat layer 2 to increase the refractive index. In order to increase the refractive index, high refractive index particles, that is, ultrafine particles of metal or metal oxide having a high refractive index can be added to the material of the hard coat layer 2. In the present invention, high refractive index particles mean particles having a refractive index of 1.6 to 2.5 and a particle size of 0.5 to 200 nm. In the antireflection film using the polyester film 1 as a base material (base), the hard coat layer 2 for reducing the reflectance has a more preferable refractive index of 1.58 to 1.85. In order to form the hard coat layer 2, the amount of the high refractive index particles can be adjusted to 5 to 70% by volume with respect to the hard coat layer 2. As the ultrafine particles of the high refractive index metal or metal oxide, particles of one or more oxides selected from titanium, aluminum, cerium, yttrium, zirconium, niobium, and antimony can be used. Specifically, for example, ZnO (refractive index 1.90), TiO ₂ (refractive index 2.3 to 2.7), CeO ₂ (refractive index 1.95), Sb ₂ O ₅ (refractive index 1.71). , _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). By including such an oxide in the hard coat layer 2 as high refractive index particles, the refractive index of the hard coat layer 2 can be increased, and reflection interference unevenness due to the hard coat layer 2 can be reduced. In addition to excellent appearance characteristics, high antireflection performance can be obtained when the low refractive index layer 3 is provided on the surface of the hard coat layer 2.

Furthermore, it is preferable that the hard coat layer 2 has an antistatic property. This prevents the hard coat layer 2 from being charged by static electricity or the like, and makes it difficult for dust to adhere to the antireflection film. Is. In order to impart antistatic properties to the hard coat layer 2, the hard coat layer 2 may be made to contain conductive nanoparticles. This is because the hard coat layer 2 is made of conductive nanoparticles, that is, a conductive metal. It is possible by adding ultrafine particles having a particle size of 0.5 to 200 nm, such as metal oxide. As the conductive nanoparticles, one or more oxide particles selected from indium, zinc, tin and antimony are preferably used. Specifically, indium oxide (ITO), tin oxide (SnO ₂ ). ), Antimony / tin oxide (ATO), lead / titanium oxide (PTO), and antimony oxide (Sb ₂ O ₅ ) ultrafine particles are preferably used. By including such an oxide as a conductive nanoparticle in the hard coat layer 2, it is possible to impart conductivity to the hard coat layer 2, the hard coat layer 2 having antistatic properties be easily provided It can be done.

Furthermore, by using the high refractive index particles and the conductive nanoparticles in combination without aggregation, it is possible to obtain the hard coat layer 2 having a high refractive index and excellent antistatic properties. Specifically, the sheet resistance of the hard coat layer 2 is preferably 10 ¹⁵ Ω / □ or less, whereby the antistatic property of the hard coat layer 2 can be improved. In addition, since the antistatic property improves as the sheet resistance of the hard coat layer 2 is smaller, the lower limit is not particularly set. However, since there is a limit to reducing the sheet resistance, the sheet resistance of the hard coat layer 2 is Substantially 10 ⁶ Ω / □ or more. Further, the sheet resistance value of the hard coat layer 2 can be adjusted by the blending amount of the conductive nanoparticles and the like. For example, the blending amount of the conductive nanoparticles is 5 to 70% by mass with respect to the total amount of the hard coat layer 2. Can be adjusted.

  In addition, before the low refractive index layer 3 is formed by applying a low refractive index coating agent for forming the low refractive index layer 3 on the surface of the hard coat layer 2, the surface treatment of the hard coat layer 2 is performed. Preferably it is done. By performing this surface treatment, the wettability and adhesion between the hard coat layer 2 and the low refractive index layer 3 can be improved. The surface treatment method is the same as the surface modification treatment applied to the polyester film 1, and includes physical surface treatment such as plasma discharge treatment, corona treatment and flame treatment, and chemical surface treatment with a coupling agent, acid and alkali. Used.

In the present invention, the low refractive index layer 3 is a layer having a lower refractive index than the polyester film 1 and the hard coat layer 2 and is formed by applying a low refractive index coating agent to the surface of the hard coat layer 2. be able to. The low refractive index layer 3 preferably has a refractive index of 1.30 to 1.45, and more preferably 1.30 to 1.40. Thereby, the reflection of light can be further reduced by the low refractive index layer 5 having a refractive index smaller than that of the hard coat layer 3, and the antireflection performance can be further enhanced. Low refractive index layer 3 having a thickness d ₃ is the refractive index of the low refractive index layer 3 n _3, and the wavelength of incident light and lambda, it is preferred that _{n 3 d 3 = λ / 4} . Specifically, the thickness d ₃ of the low refractive index layer 3 is preferably 50 to 400 nm, and more preferably 50 to 200 nm.

  The low refractive index coating agent may be prepared when the binder material itself has a low refractive index or when the binder material contains fine particles having a low refractive index. The binder material may be a silicon alkoxide type or a polymer (UV curable resin, thermosetting resin) having a saturated hydrocarbon or polyether as a main chain. A unit containing a fluorine atom may be contained therein.

  A preferred example of the silicon alkoxide is a compound represented by RmSi (OR ') n, where R and R' represent an alkyl group having 1 to 10 carbon atoms, m + n is 4, and m and n are each It is an integer. More specifically, tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, tetra Pentaethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-propoxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyl Tripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane, dimethylmethoxysilane, dimethylpropoxysilane, Methyl-butoxy silane, methyl dimethoxy silane, methyl diethoxy silane, hexyl trimethoxy silane, and their oligomers and polymers as a basic skeleton, and at least two or more kinds of copolymers.

  The polymer having a saturated hydrocarbon or polyether as the main chain is preferably crosslinked. The polymer having a saturated hydrocarbon as the main chain is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer. In order to obtain a polymer of a binder material that is crosslinked, it is preferable to use a monomer having two or more ethylenically unsaturated groups. Examples of monomers having two or more ethylenically unsaturated groups include esters of polyhydric alcohols and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, pentaerythritol). Tetra (meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate , Pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene and its derivatives (examples) 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg, divinyl sulfone), acrylamide (eg, methylenebisacrylamide) and methacrylamide are included . The polymer having a polyether as the main chain is preferably synthesized by a ring-opening polymerization reaction of a polyfunctional epoxy compound.

  Instead of or in addition to the monomer having two or more ethylenically unsaturated groups, a crosslinked structure may be introduced into the polymer of the binder material by reaction of the crosslinkable group. Examples of the crosslinkable functional group include isocyanate group, epoxy group, aziridine group, oxazoline group, aldehyde group, carbonyl group, hydrazine group, carboxyl group, methylol group and active methylene group. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane can also be used as a monomer for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. In the present invention, the cross-linking group is not limited to the above compound, and may be one that exhibits reactivity as a result of decomposition of the functional group.

  The polymerization initiator used for the polymerization reaction and crosslinking reaction of the polymer of the binder material is preferably a photopolymerization initiator rather than a thermal polymerization initiator. Examples of photopolymerization initiators include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds , Fluoroamine compounds and aromatic sulfoniums. Examples of acetophenones include 2,2-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxydimethylphenyl ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-4-methylthio-2-morpholinopropiophenone and 2 -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone is included. Examples of benzoins include benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether. Examples of the benzophenones include benzophenone, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone and p-chlorobenzophenone. Examples of phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

  The binder material is preferably a reactive organosilicon compound. When hollow silica is used for the low refractive index fine particles, wettability and dispersibility with the hollow silica particles are good if a reactive organosilicon compound is used for the binder material. As a reactive organosilicon compound, a plurality of groups that react and crosslink with heat or ionizing radiation, for example, an organosilicon compound having a polymerizable double bond group and having a molecular weight of 5000 or less is preferable. Such reactive organosilicon compounds may be one-end vinyl functional polysilane, both-end vinyl functional polysilane, one-end vinyl-functional polysiloxane, both-end vinyl-functional polysiloxane, or vinyl functionality obtained by reacting these compounds. Examples include polysilane, vinyl functional polysiloxane, and the like. Examples of specific compounds are as follows.

  Examples of other compounds include (meth) acryloxysilane compounds such as 3- (meth) acryloxypropyltrimethoxysilane and 3- (meth) acryloxypropylmethyldimethoxysilane.

  Further, in order to impart antifouling property to the low refractive index layer 3, a part of the binder material may be replaced with a water-repellent or oil-repellent material. The water- and oil-repellent materials generally include wax-based materials, and it is particularly desirable to contain a fluorine-containing compound. The effect when the fluorine compound is contained is that the surface of the low refractive index layer 3 is protected from dirt and is excellent in removal of attached dirt, fingerprints and the like. Furthermore, the frictional resistance of the surface can be reduced, and the effect of improving wear resistance can be expected.

Reducing the refractive index (n ₃ ) of the low refractive index layer 3 can be realized by adding low refractive index fine particles (refractive index: 1.20 to 1.45) to the binder material. The average particle size of the low refractive index fine particles is preferably 0.5 to 200 nm. The average particle size of the low refractive index fine particles can be measured using a concentrated particle size analyzer “FPAR1000” manufactured by Otsuka Electronics Co., Ltd., for a dispersion of low refractive index fine particles having a liquid temperature of 25 ° C. . When the average particle diameter of the low refractive index fine particles is larger than 200 nm, light is irregularly reflected by Rayleigh scattering in the obtained low refractive index layer 3, and the low refractive index layer 3 looks whitish and its haze value may increase. . On the other hand, when the average particle diameter of the low refractive index fine particles is smaller than 0.5 nm, the dispersibility of the low refractive index fine particles is lowered and aggregation occurs in the liquid of the low refractive index coating agent. The amount of the low refractive index fine particles added is preferably 20 to 99% by volume with respect to the total amount of the low refractive index layer 3. If it is less than 20% by volume, the effect of lowering the refractive index is small, and the effect of lowering the refractive index is greater as the amount of fine particles added is larger.

  When the antireflection film according to the present invention is used by being disposed on the outermost surface of a display or the like, surface hardness and abrasion resistance that can withstand actual use are required. In such a case, a high film hardness is required for the low refractive index layer 3. However, in general, when the particle-filled composite material is closely packed with spherical particles having the same particle size (completely monodispersed), the maximum volume fraction of the particles is 0.74 according to the Horsfield packing model, Due to the geometric relationship, a 24 volume% interparticle gap is inevitably produced. Therefore, ideally, when 24% by volume of binder material is added to the low refractive index layer 3 (76% by volume of low refractive index fine particles), all the voids between the low refractive index fine particles are replaced with the binder material, and high filling is achieved. In addition, a very dense thin film of the low refractive index layer 3 is obtained. However, in reality, the fine particles have a particle size distribution, and the low refractive index fine particle / binder material interface lacks wettability and the nano-sized particle size. Causes aggregation and the like. Therefore, in practice, in the region where the amount of the low refractive index fine particles added is 70% by volume or more, poor filling of the low refractive index fine particles occurs in the low refractive index layer 3, and the binder material is not filled between the low refractive index fine particles. A void resulting from the above will be generated.

  The unfilled portion of the binder material in the low refractive index layer 3 generated in the high filled region of the low refractive index fine particles significantly reduces the strength and wear resistance of the thin film. Therefore, the method of reducing the refractive index of the low-refractive index layer 3 by adding the low-refractive index fine particles is in a trade-off relationship with wear resistance completely in the high filling region of the low refractive index fine particles of 70% by volume or more. It is difficult to use.

  The low refractive index fine particles desirably have a refractive index of 1.5 or less. Specifically, fluoride fine particles such as silica fine particles, hollow silica fine particles, magnesium fluoride, lithium fluoride, aluminum fluoride, calcium fluoride, and sodium fluoride are preferable. These fine particles are used alone or in combination. These low refractive index fine particles are dispersed by being subjected to a surface treatment so as to have compatibility with the resin or the like of the binder material.

  The low refractive index fine particles contained in the low refractive index layer 3 are composed of one or more kinds of low refractive index fine particles, and it is preferable that the low refractive index fine particles contain at least a hollow silica sol. In the present invention, the hollow particles are fine particles having a cavity surrounded by an outer shell. The refractive index of the hollow particles themselves is preferably 1.20 to 1.45, and the refractive index of the hollow particles can be measured by the method disclosed in JP-A-2001-233611. Moreover, it is preferable that the average particle diameter of a hollow particle is 0.5-200 nm. The material constituting the outer shell of the hollow particles is preferably a metal oxide in addition to silica. It is preferable to use hollow particles having a thin outer shell compared to the average particle diameter, and the volume of hollow silica fine particles (including internal cavities) in the low refractive index layer 3 is large ( 40% by volume or more) is preferable. Such hollow particles are disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-233611, and the hollow particles disclosed therein can be used when preparing a low refractive index coating agent.

Specific examples of the material constituting the outer shell of the hollow particles include SiO ₂ , SiO _x , TiO ₂ , TiO _x , SnO ₂ , CeO ₂ , Sb ₂ O ₅ , ITO, ATO, Al ₂ O _{3 and the} like. Or a material in the form of a mixture of any combination of these materials. Further, a composite oxide of any combination of these materials may be used. Note that SiO _x is preferably SiO ₂ when fired in an oxidizing atmosphere.

  The low refractive index coating agent is a liquid phase method (dip coating method, spin coating method, spray coating method, roll coating method, gravure roll coating method, reverse coating method, transfer roll coating method, micro gravure coating method, cast coating method, It is preferable to apply on the hard coat layer 2 that has been surface-treated by a calendar coating method, a die coating method, or the like. After coating, the solvent in the coating film is volatilized by heating and drying, and then the coating film is cured by heating, humidification, ultraviolet irradiation, electron beam irradiation, etc., and the low refractive index layer 3 can be formed.

Moreover, in this invention, as shown in FIG. 1, the absorption layer 4 is provided in the other surface (surface on the opposite side to the side which provided the hard-coat layer 2) of the polyester film 1. As shown in FIG. The absorption layer 4 has a role of absorbing (correcting) unnecessary light normally generated as a by-product from the display. Specifically, the absorption layer 4 is emitted from the plasma light emitting unit and malfunctions the remote controller or the like. This is a function of absorbing infrared rays (≧ 800 nm) or adjusting neon color display by absorbing neon plasma emission light (580 to 600 nm). And this absorption layer 4 can be formed with the binder resin containing any one or both of a pigment | dye and a pigment. The maximum absorption wavelength λ _max of the absorption layer 4 is in the range represented by the formula 550 (nm) ≦ λ _max ≦ 650 (nm). As a result, an increase in reflectance due to multiple interference can be suppressed, and the effect of reducing reflection can be enhanced.

  Here, the binder resin preferably has an acrylate functional group, for example, a relatively low molecular weight polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, spiroacetal resin, Polybutadiene resin, polythiol polyene resin, oligomers such as (meth) acrylates of polyfunctional compounds such as polyhydric alcohols, prepolymers, and reactive diluents such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, Monofunctional monomers such as N-vinylpyrrolidone, as well as polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, die A relatively large amount of lenglycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, etc. Can be used.

  Moreover, it does not specifically limit as a pigment | dye or a pigment, For example, a porphyrin pigment | dye, an azaporphyrin pigment | dye, etc. can be used. Furthermore, in order to provide the absorption layer 4 with an infrared absorption function, an imonium dye, tungsten oxide, or the like can be used as the dye or pigment.

  In the present invention, in order to further improve the antifouling property and fingerprint removing property of the antireflection film, as shown in FIG. 2, an antifouling layer 5 is provided on the surface of the low refractive index layer 3, and this antifouling layer is provided. The low refractive index layer 3 is preferably coated with 5. Since the thickness of the antifouling layer 5 does not affect the optical characteristics, it is preferable to set it to 30 nm or less. Further, the antifouling layer 5 is formed by covering the surface of the low refractive index layer 3 with a silicone or fluorine-containing compound. As materials for forming the antifouling layer 5, those having reactivity with a substrate such as a fluorine compound having an alkoxysilano group and a reactive silicone oil improve wear resistance, chemical resistance, and aging resistance. This is preferable.

  As the antifouling material for forming the antifouling layer 5, for example, a long chain fluoroalkylsilane coating agent “XC98-B2472” manufactured by GE Toshiba Silicone is used, and this is diluted with a diluting solvent IPA (isopropanol). After diluting to 0.2% by mass and applying this mixture to the surface of the low refractive index layer 3 with a wire bar coater # 10 so as to have a film thickness of 15 nm, it is dried at 120 ° C. for 15 minutes to prevent The dirty layer 5 can be formed. The performance evaluation of the antifouling layer 5 can include fingerprint wiping properties. That is, immediately after the fingerprint is adhered to the antifouling layer 5 and the surface is soiled, it is wiped 50 times with Kimwipe (manufactured by Jujo Kimberley Co., Ltd.). Cellophane tape ("CT24", manufactured by Nichiban Co., Ltd.) is attached to the wiped portion and peeled off, and visually observed from a distance of 40 cm to evaluate the degree of removal of dirt.

  Hereinafter, the present invention will be specifically described by way of examples.

  As the polyester film (transparent substrate film) 1, a polyethylene terephthalate (PET) film (“A1549 (100 μm film thickness, refractive index 1.65) manufactured by Toyobo Co., Ltd.) was used.

The hard coat layer 2 is prepared by dispersing various nanoparticles in an acrylic ultraviolet curable resin (“Seika Beam PET-HC15” active ingredient (solid content) 60 mass%, manufactured by Dainichi Seika Kogyo Co., Ltd.). This hard coat material (mixed solution) is applied to the surface of the polyester film 1 with a wire bar coater # 10, dried at 80 ° C. for 1 minute, and then cured by UV irradiation (600 mJ / cm ² ). Formed. Among the above-mentioned various nanoparticles, titanium oxide particles “760T” (dispersion solvent: toluene, solid content 48% by mass) manufactured by Teika Co., Ltd. were used as the high refractive index particles. In addition, among the above-mentioned various nanoparticles, as the conductive nanoparticles, ATO particles “ELCOM P-special product A” manufactured by Catalyst Chemical Industry Co., Ltd. (dispersion solvent: MEK / toluene (4/1), solid content: 30 mass) %) Was used. In addition, in the following [Table 1], the compounding amounts (both mass%) of titanium oxide particles and ATO particles in the hard coat layer 2 of Examples 1 to 3 and Comparative Examples 1 to 6 (described later), the hard coat layer 2 the refractive index _{(n 2)} and the optical thickness _{(n 2 d} 2).

  The low refractive index layer 3 was formed by applying a low refractive index coating agent to the surface of the hard coat layer 2. The low refractive index coating agent was prepared as follows. First, 356 parts by mass of methanol is added to 208 parts by mass of tetraethoxysilane, 18 parts by mass of water and 18 parts by mass of 0.01N hydrochloric acid aqueous solution are added, and this is mixed with a disper to obtain a mixed solution. It is used as a silicone resin (A) having a weight average molecular weight adjusted to 850 by stirring for 2 hours in a thermostatic bath at 0 ° C. Next, the following low refractive index nanoparticles (1) and (2) are used as silicone as low refractive index fine particles. In addition to the resin (A), the low refractive index nanoparticles / silicone resin are blended so as to have a desired volume ratio in terms of condensed solids, and then diluted with methanol so that the total solid content is 1% by mass. To prepare a low refractive index coating agent and apply the low refractive index coating agent to the surface of the hard coat layer 2 with a wire bar coater # 10 so that the film thickness is 100 nm. After cloth, 120 ° C., to form a low refractive index layer 3 and dried for 15 minutes. As the low refractive index nanoparticles (1), hollow silica IPA (isopropanol) dispersion sol (Thruria CS-60IPA, solid content 20 mass%, manufactured by Catalyst Kasei Kogyo Co., Ltd.) was used. As the low refractive index nanoparticles (2), organosilica sol (IPA-ST, solid content of 30% by mass, manufactured by Nissan Chemical Co., Ltd.) was used. In addition, in the following [Table 1], the compounding amounts of “CS-60IPA” and “IPA-ST” in the low refractive index layer 3 of Examples 1 to 3 and Comparative Examples 1 to 6 (described later) (both are volume%). Indicates.

The absorption layer 4 is formed by dissolving a dye / pigment in an acrylic ultraviolet curable resin (“SEICA BEAM PET-HC15” active ingredient (solid content) 60 mass%, manufactured by Dainichi Seika Kogyo Co., Ltd.). This absorbent layer forming material was prepared and applied to the back surface of the polyester film 1 with a wire bar coater # 10, dried at 80 ° C. for 1 minute, and then cured by UV irradiation (600 mJ / cm ² ). As the dye / pigment, “TY169” manufactured by Adeka Corporation was used, and 0.001 part by mass was added to 100 parts by mass of the acrylic ultraviolet curable resin.

(Comparative Example 1)
The hard coat material in which 50% by mass of titanium oxide particles “760T” were dispersed was coated on the surface of the PET film “A1549” to obtain a hard coat layer 2 having an optical film thickness of 1090 nm. Further, a low refractive index coating agent in which 40% by volume of “CS-60IPA” in a total amount was dispersed in the silicone resin (A) matrix was coated with a wire bar coater so as to have a physical film thickness of about 100 nm. Then, it hardened | cured on 120 degreeC and the conditions for 15 minutes, and the antireflective film like FIG. 3 was manufactured by providing the low-refractive-index layer 3. FIG.

Example 1
An antireflection film as shown in FIG. 1 was produced in the same manner as in Comparative Example 1 except that the absorption layer 4 was provided on the back surface of the PET film “A1549”.

(Comparative Example 2)
An antireflection film as shown in FIG. 3 was produced in the same manner as in Comparative Example 1 except that the blending amount of the titanium oxide particles “760T” in the hard coat layer 2 was 10 mass% and the optical film thickness was 940 nm. .

(Example 2)
An antireflection film as shown in FIG. 1 was produced in the same manner as in Comparative Example 2 except that the absorption layer 4 was provided on the back surface of the PET film “A1549”.

(Example 3)
A wire bar coater with an antifouling material (an antifouling material “OPTOOL DSX” manufactured by Daikin Industries, Ltd.) on the low refractive index layer 3 of the antireflection film produced in Example 1 so that the physical film thickness is about 15 nm. Coated with. Thereafter, the film was cured at 120 ° C. for 15 minutes to provide the antifouling layer 5 to produce an antireflection film as shown in FIG.

(Comparative Example 3)
An antireflection film as shown in FIG. 3 was produced in the same manner as in Comparative Example 1 except that the optical film thickness of the hard coat layer 2 was 940 nm.

(Comparative Example 4)
An antireflection film as shown in FIG. 1 was produced in the same manner as in Comparative Example 3 except that the absorption layer 4 was provided on the back surface of the PET film “A1549”.

(Comparative Example 5)
An antireflection film as shown in FIG. 3 was produced in the same manner as in Comparative Example 1 except that the blending amount of the titanium oxide particles “760T” in the hard coat layer 2 was 10 mass% and the optical film thickness was 1090 nm. .

(Comparative Example 6)
An antireflection film as shown in FIG. 1 was produced in the same manner as in Comparative Example 5 except that the absorption layer 4 was provided on the back surface of the PET film “A1549”.

  Table 1 below shows the evaluation results of the antireflection films (samples) of Examples 1 to 3 and Comparative Examples 1 to 6. Each evaluation method is as follows.

  Minimum reflectance: Using a spectrophotometer "U-4100" manufactured by Hitachi High-Technologies Corporation, the sample surface on the low refractive index layer 3 side was measured with regular reflection of 5 degrees based on JIS R-3106.

  Adhesiveness (cross-cut tape test): A cross-cut tape peeling test was performed on the sample in accordance with JIS D0202-1988. Using cellophane tape (“CT24”, manufactured by Nichiban Co., Ltd.), the sample was adhered to the sample with the finger pad and then peeled off. Judgment is represented by the number of squares not to be peeled out of 100 squares, where 100/100 is the case where no peeling occurs, and 0/100 is the case where the peeling is complete.

  Pencil hardness: A sample was fixed on a 2 mm thick glass plate with a cellophane tape, and a scratch test was performed with a pencil in accordance with JIS K5400-1990. The load during the test is 1000 g.

Fingerprint wiping property: A fingerprint was actually attached to a sample with a human finger, and was wiped several times using BEMCOT (manufactured by Asahi Kasei, M-3). And the state when it wiped off was observed visually. The results were evaluated in five stages as follows.
5: What can be easily wiped in 1 to 3 times.
4: What can be wiped off less than 10 times.
3: Can be wiped off 10 times or more, but requires many times.
2: What is very difficult to wipe off.
1: What cannot be wiped off.

It is sectional drawing which shows an example of the antireflection film concerning this invention. It is sectional drawing which shows another example of the antireflection film concerning this invention. It is sectional drawing which shows an example of the conventional antireflection film.

Explanation of symbols

1 Polyester film 2 Hard coat layer 3 Low refractive index layer 4 Absorbent layer 5 Antifouling layer

Claims (8)

An antireflection film formed by providing a hard coat layer and a low refractive index layer in this order on one side of a polyester film, and providing an absorption layer containing either or both of a dye and a pigment on the other side of the polyester film The maximum absorption wavelength λ _max of the absorption layer is in the range represented by the formula 550 (nm) ≦ λ _max ≦ 650 (nm), and is harder than the refractive index (n ₁ ) of the polyester film. When the refractive index (n ₂ ) of the layer is large, the optical film thickness (n ₂ d ₂ ) of the hard coat layer is in the range represented by the following formula (1), and the refractive index (n ₁ ) of the polyester film ) refractive index of the hard coat layer than (n ₂₎ when is small, Ri range near the optical thickness of the hard coat layer (n 2 _{d 2)} is expressed by the following equation (2), the polyester fill The wavelength at which the reflectance becomes the minimum value of the antireflection layer composed of three layers of the hard coat layer and the low refractive index layer, antireflection, characterized in der Rukoto the range of 550nm or more 650nm or less and the film.
(1) n ₂ d ₂ = (490 + 300 × m) ± 50 (nm)
(2) n ₂ d ₂ = (640 + 300 × m) ± 50 (nm)
(However, d ₂ (nm) is the physical film thickness of the hard coat layer, n ₂ d ₂ <4000 (nm), and m is a positive integer.) _{2. The} antireflection film according to claim 1, wherein the hard coat layer has a refractive index (n ₂ ) of 1.50 to 1.90.   3. The antireflection according to claim 1, wherein at least one oxide selected from titanium, aluminum, cerium, yttrium, zirconium, niobium, and antimony is contained in the hard coat layer as high refractive index particles. the film.   The antireflection film according to any one of claims 1 to 3, wherein the hard coat layer has antistatic properties.   The antireflection film according to any one of claims 1 to 4, wherein at least one oxide selected from indium, zinc, tin, and antimony is contained in the hard coat layer as conductive nanoparticles. . 6. The antireflection film according to claim 1, wherein the sheet resistance of the hard coat layer is 10 ¹⁵ Ω / □ or less. The antireflective film according to claim 1, wherein a refractive index (n ₃ ) of the low refractive index layer is 1.30 to 1.45.   The antireflection film according to claim 7, wherein an antifouling layer is provided on the surface of the low refractive index layer.

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