JP5372417B2 - Antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film which is excellent in appearance characteristic by suppressing interference irregularity due to reflection, has high antireflection performance and can reduce the occurrence of separation of a hard coat layer, and to provide a manufacturing method of the antireflection film. <P>SOLUTION: The antireflection film comprises: a polyester film; an easily adhesive layer formed on the polyester film 1; a hard coat layer 2 formed on the easily adhesive layer; and a low refractive index layer 3 formed on the hard coat layer, wherein the refractive index of the hard coat layer is 1.58 to 1.85 and the reflectance on the easily adhesive layer side of the polyester film on which the easily adhesive layer is formed is 4% or more. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an antireflection film. Such an antireflection film is suitably applied to the surface of a display member such as a CRT display, a plasma display, a liquid crystal display, a projection display, and an EL display, and a housing material such as a window and a show window. When applied, reflection of light from the outside of the display or the like can be prevented.

  In recent years, various displays have become widespread with the progress of multimedia. And various functional films which have various functions with respect to such a display are requested | required. Among these, great expectations are placed on antireflection films for the purpose of preventing light reflection.

As such an antireflection film, a polyester film having excellent mechanical properties, heat resistance, chemical resistance and the like is usually used. Such a polyester film has excellent properties as described above, and therefore, a magnetic tape, a ferromagnetic thin film tape, a packaging tape, a packaging film, a film for electronic parts, an electrical insulating film, a laminating film, a display, etc. It is used as a screen film and a protective film for various members. In particular,
Used as base film for prism lens sheet, touch panel, backlight, etc., base film for TV antireflection film, antireflection film for front optical filter of plasma TV, near infrared cut film, electromagnetic shielding film base film, etc. Yes.

  A base film used for an optical film such as an antireflection film is required to have excellent transparency so that light from a display can be transmitted as much as possible. On the other hand, a hard coat layer for surface protection, for example, is applied to the base film in order to ensure the properties as an optical film or enhance the function. In this case, the base film is coated with such a coating. Excellent easy adhesion to the material is required.

  However, since the normally used polyester film has high crystallinity, it is generally difficult to ensure adhesion with the coating material and the like. Therefore, for example, in order to ensure easy adhesion with the hard coat layer, a method of coating an easy-adhesion film on the surface of the polyester film, the surface of the polyester film is subjected to gas phase surface treatment such as corona treatment, frame treatment, etc. Methods and chemical surface treatment methods such as primer application are used. In particular, when a PET film is used as a display application, high transparency and adhesion are required, and therefore, an easy-adhesion layer having a thickness of nanometer order is generally interposed (Patent Document 1).

  When a polyester film coated with such an easy-adhesion layer is used as the base film, as described above, high transparency and adhesion with the hard coat layer can be ensured, and blocking resistance is also improved. Can do.

  However, when a polyester film having such an easy-adhesion layer is used as an anti-reflection film, due to factors such as mismatch between the refractive index of the easy-adhesion layer and the refractive index of the polyester film, and variations in the film thickness of the easy-adhesion layer However, there is a problem that optical interference unevenness occurs when a hard coat layer or the like is coated thereon.

  Moreover, due to the above-mentioned refractive index mismatch, the reflection interface is increased, resulting in a problem of increased reflectance. On the other hand, although it is also conceivable to use a polyester film that does not have an easy-adhesion layer, in this case, there is a concern about peeling of the hard coat layer.

On the other hand, in order to reduce the reflectance of the antireflection film, a method for increasing the refractive index difference between the hard coat layer and the low refractive index layer has been proposed. In order to realize this configuration, a method for increasing the refractive index of the hard coat layer or a method for decreasing the refractive index of the low refractive index layer can be considered. In addition, a method has been proposed in which two hard coat layers are provided and a second hard coat layer higher than the refractive index of the first hard coat layer is inserted between the first hard coat layer and the low refractive index layer (Patent Document 2). . These techniques are excellent methods for reducing the light reflection at the air / low refractive index layer and the low refractive index layer / hard coat layer interface, but the light reflection at the hard coat layer / PET interface is It cannot be suppressed. In particular, when the refractive index of the hard coat layer is increased, the reflection at the interface between the easy-adhesion layer and the hard coat layer of the PET film to be used increases conversely, and the total reflectance of the antireflection film increases. Occurred.
Japanese Patent Laid-Open No. 9-220791 JP 2004-69867 A

The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to suppress interference unevenness due to reflection and to have excellent appearance characteristics, high antireflection performance, and hardware. it is to provide an antireflection fill beam that can reduce the occurrence of peeling of the coating layer.

  As a result of intensive studies on the above problems, the inventors of the present invention, in order to prevent the hard coat layer from being peeled off from the polyester film, the surface treatment of the polyester film and adhesion of the hard coat layer are required. From the viewpoint of transparency, it has been considered that it is necessary to interpose an easy-adhesion layer between the hard coat layer and the polyester film to facilitate the adhesion between them.

  However, when an easy-adhesion layer is interposed between the hard coat layer and the polyester film, there is a problem that interference unevenness occurs due to light reflected at the interface between the hard coat layer and the easy-adhesion layer. As a result of further investigations, the present inventors have found that the occurrence of unevenness in interference can be reduced by setting the reflectance of the polyester film having the easy adhesion layer to a predetermined value or more. The present invention has been completed.

The present invention comprises a polyester film, an easy adhesion layer formed on the polyester film, a hard coat layer formed on the easy adhesion layer, and a low refractive index layer formed on the hard coat layer. An antireflection film comprising:
The refractive index of the hard coat layer is 1.58 to 1.85,
The easy adhesion layer has a thickness of 5 nm to 80 nm and a refractive index of 1.61 to 1.75.
8% der less reflectivity of 6.1% or more of the adhesive layer side of the polyester film the adhesive layer is formed is,
The refractive index of the low refractive index layer to provide an antireflection film characterized in 1.30 to 1.45 der Rukoto.

  In another aspect, the present invention further includes a second hard coat layer having a refractive index of 1.60 to 2.00 between the hard coat layer and the low refractive index layer. The antireflection film is characterized in that the refractive index of the hard coat layer is higher than the refractive index of the hard coat layer. In particular, the optical film thickness of the second hard coat layer is preferably 80 nm to 600 nm.

This reflectivity is a condition of a regular reflectivity of 5 ° by using U-4100 manufactured by Hitachi, Ltd., polishing the back side of the film with steel wool, and then painting with black paint, ignoring the back side reflection. It is a value obtained by measuring with .

According to the above-described antireflection film of the present invention, since a film having a reflectance of 6.1 % or more is used, reflection interference unevenness due to an easy-adhesion film can be reduced, and appearance characteristics are excellent. The antireflection performance can be enhanced, and the occurrence of peeling of the hard coat layer can be reduced. Rather than forming a hard coat layer by chemically treating the surface of the polyester film, an easy-adhesion layer is interposed between the hard coat layer and the polyester film to reduce the occurrence of peeling of the hard coat layer. Can do.

  The antireflection film according to the present invention will be described in more detail with reference to the drawings. FIG. 1 schematically shows an example of the antireflection film of the present invention. The antireflection film according to the present invention was adhered to the polyester film 1 as a transparent substrate having an easy adhesion layer, the hard coat layer 2 formed on the easy adhesion layer of the polyester film, and the hard coat layer 2. Low refractive index layer 3. In addition, in FIG. 1, illustration of the easily bonding layer located between a polyester film and a hard-coat layer is abbreviate | omitted. Usually, composites in which an easy-adhesion layer is formed on a polyester film are commercially available, and can be used in the antireflection film of the present invention. If necessary, as shown in FIG. 1, an antifouling layer 4 formed on the low refractive index layer 3 may be provided.

  The antireflection film is a film that reduces reflectance by canceling out wavelengths, that is, prevents reflection. This is because the light reflected at the interface between the low refractive index layer and the antifouling layer interferes with the light reflected at the interface between the low refractive index layer and the hard coat layer, canceling the amplitude and reflecting The rate is reduced. Such destructive interference is made by appropriately selecting the refractive index of the low refractive index layer and the base film, and the thickness of the low refractive index layer.

In the antireflection film of the present invention, the refractive index of the easily adhesive layer is 1. 61 to 1.75 is preferable. In this case, the refractive index difference between the hard coat layer and the easy-adhesion layer is more appropriately suppressed, and as a result, the above effect becomes more remarkable.

  The polyester forming the polyester film 1 used in the present invention includes an aromatic dicarboxylic acid component (for example, terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 4,4′-diphenyldicarboxylic acid, etc.) and a glycol component (for example, An aromatic polyester composed of ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol and the like is preferable. In particular, polyethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate are preferable. Moreover, the copolymer polyester of the component illustrated above may be sufficient.

  In the antireflection film of the present invention, the polyester film is an organic film as a lubricant, if necessary, in order to improve the roll-up property of the film during film formation and the transportability of the film when forming the hard coat layer. Alternatively, 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 or instead of the fine particles, a colorant, an antistatic agent, an ultraviolet absorber, an antioxidant, a lubricant, a catalyst, other resins, etc. are optionally contained within a range that does not impair the transparency of the film. Can be made.

  In the antireflection film of the present invention, the polyester film preferably 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 point of view, in order to improve the blocking resistance in a roll state, the slipperiness, and the adhesion with the hard coat layer while maintaining high transparency with a haze of 3% or less, an easy adhesion layer (preferably a nanometer A polyester film coated with a thickness of the order, more preferably 5-80 nm, is used in the antireflection film of the present invention.

  However, when a polyester film coated with such an easy-adhesion layer is used, the refractive index of the easy-adhesion layer is generally different from the refractive index of the base polyester. When the difference in refractive index between the easy-adhesion layer and the hard coat layer is large, when coating the hard coat layer, non-uniformity in appearance interference occurs due to the film thickness unevenness of the easy-adhesion layer and the hard coat layer 2. There's a problem. When a hard coat layer having a refractive index of 1.58 to 1.85 is provided on a polyester film with an easy adhesive layer, such as a PET film, optically hard coat / adhesive layer and easy adhesive layer / Reflection occurs at the PET interface, which deteriorates the reflectance characteristics and interference unevenness characteristics of the antireflection film. In order to suppress this reflection, it is necessary to suppress the optical adverse effect caused by the easily adhesive layer. The reflectance of the polyester film with the easy adhesion layer is such that the refractive index of the easy adhesion layer used decreases from the refractive index of the polyester film (for example, n = 1.69 in the case of a PET film), and the film of the easy adhesion layer The thickness decreases as the thickness approaches 100 nm. On the contrary, when the optical adverse effect of the easy-adhesion layer is excluded, the reflectance approaches the reflectance of the polyester film (for example, 6.5% in the case of a film of PET alone). In the present invention, in consideration of such matters, as the polyester film to be used, a film having a reflectance of 4% or more of the polyester film with an easy-adhesion layer on the side in contact with the hard coat layer is used. It is characterized by suppressing.

  In order to increase the reflectance of the polyester film with an easy adhesion layer (for example, PET film) as described above, it is preferable to control the film thickness of the easy adhesion layer to 5 nm or more and 80 nm or less. If the thickness is 5 nm or less, the easy-adhesive material cannot be uniformly coated on the polyester film, and it becomes difficult to ensure stable adhesion between the polyester film and the hard coat layer. When the thickness is 80 nm or more, reflection on the easy-adhesion layer increases, and problems such as an increase in reflectivity as an antireflection film and deterioration in interference unevenness occur. Moreover, in order to raise the reflectance of the polyester film (for example, PET film) with an easily bonding layer, it is preferable that the refractive index of an easily bonding layer shall be 1.55-1.75. When it is 1.58 or less or 1.75 or more, the difference between the refractive index of the hard coat material and the polyester film 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. However, in order to improve the hardness of the hard coat layer 2, a reactive curable resin such as 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 (a composition for forming a hard coat layer).

  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 is formed using a thermosetting resin, it is preferable that the thermosetting resin is applied to the surface of the easy-adhesion layer of the polyester film 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 applied to the surface of the easy-adhesion layer of the polyester film, dried, and then cured by ultraviolet irradiation. Is preferred.

  The hard coat layer 2 preferably has a refractive index close to that of the polyester film 1. Practically 1.58 to 1.85 are preferable for the reason of reducing the reflectance. 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 hard coat layer 2 composed of the above components is usually about 1.49 to 1.52. However, in the antireflection film of the present invention, the hard coat layer 2 contains high refractive index particles and has a refractive index. To increase the antireflection performance. Therefore, high refractive index particles, that is, ultrafine particles of a high refractive index metal or metal oxide can be added to the hard coat layer material.

In the present invention, the high refractive index particles preferably have a refractive index of 1.6 or more, and preferably have a particle size of 0.5 nm to 200 nm.
In the antireflection film having a polyester film as a base material (base), the preferred refractive index of the hard coat layer for reducing the reflectance is 1.58 to 1.85 as described above. In order to form the hard coat layer 2 having the above, the blending amount of the high refractive index particles can be adjusted to 5 to 70% by volume with respect to the hard coat layer.

As the ultrafine particles of the metal or metal oxide having a high refractive index, particles comprising one or more oxides selected from titanium, aluminum, cerium, yttrium, zirconium, niobium, and antimony are used. it can. 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 Examples thereof include fine powders such as O ₃ (refractive index 1.63).

In the antireflection film of the present invention, it is further preferable to impart antistatic properties to the hard coat layer, thereby enabling antistatic properties and dust adhesion prevention as an antireflection film. In order to impart antistatic properties to the hard coat layer 2, the hard coat layer may contain conductive nanoparticles as an antistatic agent. Specifically, it becomes possible by adding conductive nanoparticles, that is, ultrafine particles of a conductive metal or metal oxide and having a particle size of, for example, 0.5 to 200 nm to the hard coat layer material. As the conductive nanoparticles, particles containing one or more oxides selected from indium, zinc, tin, and antimony are preferably used. Specifically, indium oxide (ITO), tin oxide ( It is preferable to use ultrafine particles of SnO ₂ ), antimony / tin oxide (ATO), lead / titanium oxide (PTO), and antimony oxide (Sb ₂ O ₅ ).

In the antireflection film of the present invention, a hard coat layer having a high refractive index and an excellent antistatic property can be obtained by using the high refractive index particles and the conductive nanoparticles in combination without aggregation. In order for the hard coat layer to have antistatic properties, the sheet resistance is preferably 10 ¹⁵ Ω / □ or less. In addition, since the antistatic property improves as the sheet resistance of the hard coat layer decreases, the lower limit is not particularly set, but there is a limit to reducing the sheet resistance, so the lower limit of the sheet resistance of the hard coat layer is It becomes substantially 10 ⁶ Ω / □. Further, the sheet resistance value of the hard coat layer can be adjusted by the blending amount of the conductive nanoparticles, for example, the blending amount of the conductive nanoparticles is, for example, 5 to 70% by mass with respect to the hard coat layer. Can be adjusted.

  In the present application, a second hard coat layer 2 ′ (not shown) having a refractive index of 1.60 to 2.00 is provided between the hard coat layer 2 having a refractive index of 1.58 to 1.85 and the low refractive index layer. Further, it is preferable that the second hard coat layer 2 ′ has a refractive index higher than that of the hard coat layer 2. Regarding the high refractive index of the second hard coat layer 2 ′, the refractive index is increased by adding high refractive index particles, that is, ultrafine particles of a metal or metal oxide having a high refractive index, to the hard coat layer material. The antireflection performance can be enhanced. A second hard coat layer 2 ′ having a refractive index of 1.60 to 2.00 is further provided between the hard coat layer 2 and the low refractive index layer, and the refractive index of the second hard coat layer 2 ′ By configuring so as to be higher than the refractive index of the layer 2, the amount of light transmitted through the low refractive index layer / second hard coat layer interface can be reduced, and at the interface between the hard coat layer 2 and the easy adhesion layer. The reflection of light can be suppressed. Therefore, with the above configuration, the antireflection performance can be increased.

  In the present invention, the optical film thickness of the second hard coat layer 2 ′ is preferably 80 nm to 600 nm. Further, by setting the optical film thickness of the second hard coat layer 'to 80 nm to 600 nm, the antireflection performance can be further enhanced. Here, the optical film thickness is obtained by multiplying the refractive index of the film by the actual film thickness. In order to reduce the reflectivity by inserting a high refractive index layer on the medium refractive index (around 1.5) hard coat layer 2, the optical film thickness is usually about 50 to 200 nm. (Japanese Unexamined Patent Application Publication No. 2004-69867). In the case of an antireflection film in which the refractive index and film thickness of the easy-adhesion layer of the PET substrate cannot be optically ignored, the hard coat layer needs to have a medium refractive index. When the second hard coat layer is inserted in such a configuration, the optical film thickness of the second hard coat layer is about 50 to about λ / 4 (140 nm) because the refractive index difference between the hard coat layer and the second hard coat layer is large. If it is not about 200 nm, the reflectance reduction effect will not be exhibited. In addition, in the case of the conventional configuration, for example, when the optical film thicknesses of the low refractive index layer and the second hard coat layer are both 140 nm (λ / 4), the level of reflected light at the interface of the low refractive index layer and the second hard coat layer. Although the phase difference becomes 180 ° and the minimum reflectance at 560 nm can be reduced, the reflectance near 400 to 550 nm and around 650 to 800 nm other than the phase difference of 180 ° increases conversely, resulting in blue and red It becomes a film with strong reflection color. In addition, precise film thickness control with a narrow control width of 50 to 200 nm is required, which causes a problem in production yield.

  When the configuration of the present invention is adopted, the influence of the easy-adhesion layer of the PET base material can be optically ignored. Therefore, the effect of reducing the reflectivity is produced by increasing the refractive index of the hard coat layer itself. In addition, by further increasing the refractive index of the second hard coat layer than the refractive index of the hard coat layer, it is possible to impart a refractive index difference from the PET substrate in an inclined manner. Therefore, in the configuration of the present invention, reflection can be prevented by the principle of a combination of two layers of a high refractive index layer and a low refractive index layer, and strict film thickness control of the second hard coat layer is unnecessary. In addition, since the reflectivity is reduced by the pseudo two-layer configuration, not only the minimum reflectivity reduction at 550 nm but also the reflectivity can be reduced in the entire visible range of 400 to 800 nm. In addition, since the optical film thickness control management width of the second hard coat layer 2 ′ is as wide as 80 nm to 600 nm, the production yield can be dramatically improved as compared with the conventional configuration.

  In order to form a low refractive index layer on the surface of the hard coat layer as described above, a low refractive index layer is formed by applying a low refractive index coating agent or the like. It is preferable to carry out. By performing this surface treatment, it becomes possible to improve the wettability and adhesion between the hard coat layer and the low refractive index layer. 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. It is used.

In the antireflection film of the present invention, the low refractive index layer is a layer having a refractive index smaller than that of the polyester film and the hard coat layer. The low refractive index layer 3 preferably has a refractive index of 1.30 to 1.45, more preferably 1.30 to 1.40.
The thickness d of the low refractive index layer preferably satisfies nd = λ / 4, where n is the refractive index of the low refractive index layer and λ is the wavelength of incident light. Specifically, the thickness of the low refractive index layer is preferably 50 to 400 nm, and more preferably 50 to 200 nm.

  The low refractive index coating agent comprises a binder material and optionally present particulates. In this case, there are a case where the binder material itself has a low refractive index and a case where the binder material is prepared by containing fine particles having a low refractive index. The binder material may be a silicon alkoxide-based material or a polymer having a saturated hydrocarbon or polyether as a main chain (for example, a UV curable resin, a thermosetting resin, or the like). You may contain the unit containing a fluorine atom in a polymer chain.

  A preferred example of a silicon alkoxide-based material is a silicon alkoxide represented by RmSi (OR ′) n (where R and R ′ represent an alkyl group having 1 to 10 carbon atoms, m + n is 4, m and n Are each an integer)) and oligomers and polymers (including copolymers) having one or more of them as a basic skeleton. Specific examples of such alkoxides include tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra- tert-butoxysilane, tetrapentaethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-propoxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane, methyltrimethoxysilane, Methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane, dimethylmethoxysilane Dimethyl propoxysilane, dimethyl-butoxy silane, methyl dimethoxy silane, methyl diethoxy silane, hexyl trimethoxy silane and the like. An oligomer or a polymer can be obtained by hydrolyzing and condensing the alkoxy group of such an alkoxide.

The hydrolysis of the silicon alkoxide is performed by dissolving the silicon alkoxide in a suitable solvent. Examples of the solvent used include alcohols such as methyl ethyl ketone, isopropyl alcohol, methanol, ethanol, methyl isobutyl ketone, ethyl acetate and butyl acetate, ketones, esters, halogenated hydrocarbons, aromatic hydrocarbons such as toluene and xylene, Or the mixture of these is mentioned. The alkoxide is dissolved in the solvent so as to be 0.1% or more, preferably 0.1 to 10% by weight in terms of SiO ₂ generated when the alkoxide is 100% hydrolyzed and condensed. If the concentration of the SiO ₂ sol is less than 0.1% by weight, the formed sol film cannot sufficiently exhibit the desired characteristics, while if it exceeds 10% by weight, it becomes difficult to form a transparent homogeneous film. Moreover, in this invention, if it is less than the above-mentioned solid content, it is also possible to use another organic substance and an inorganic binder together.

Water more than the amount necessary for hydrolysis is added to this solution, and stirring is performed at a temperature of 15 to 35 ° C, preferably 22 to 28 ° C, for 0.5 to 10 hours, preferably 2 to 5 hours. In the hydrolysis, it is preferable to use a catalyst. As these catalysts, acids such as hydrochloric acid, nitric acid, sulfuric acid or acetic acid are preferable, and these acids are contained in about 0.001 to 20.0 N, preferably 0.005. It can be added as an aqueous solution of about ˜5.0 N, and water in the aqueous solution can be used as water for hydrolysis. The SiO ₂ sol obtained as described above is a colorless and transparent liquid, is a stable solution having a pot life of about 1 month, has good wettability with respect to the substrate, and has excellent coating suitability.

In the production of the antireflection film of the present invention, it is preferable to add a reactive organosilicon compound or a partial hydrolyzate thereof to the SiO ₂ sol. As the reactive organosilicon compound, in addition to the above-described reactive organosilicon compound such as silicon alkoxide, a plurality of groups that are reactively crosslinked by heat or ionizing radiation, for example, a molecular weight of 5000 or less having a polymerizable double bond group The organosilicon compound is a preferable material. Such 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 a vinyl functional polysilane obtained by reacting these compounds, Or a vinyl functional polysiloxane etc. are mentioned.

  The polymer having the above-mentioned saturated hydrocarbon as the main chain is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer. The polymer having a polyether as the main chain is preferably synthesized by a ring-opening polymerization reaction of a polyfunctional epoxy compound. Such a polymer having a saturated hydrocarbon or polyether as the main chain is preferably crosslinked. 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 .

  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 binder material is more preferably a photopolymerization initiator 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.

  As described above, the binder material is preferably a reactive organosilicon compound such as silicon alkoxide. When, for example, hollow silica is used as the low-refractive-index fine particles, which are fine particles that are present as required, if silicon alkoxide and the other reactive organosilicon compounds described above are used as the binder material, wettability and dispersion with hollow silica particles Good properties. As another reactive organosilicon compound, a plurality of groups that undergo reactive crosslinking by heat or ionizing radiation, for example, an organosilicon compound having a molecular weight of 5000 or less having a polymerizable double bond group can be mentioned as a preferred material. 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 a vinyl functionality obtained by reacting these compounds. Examples include polysilane, vinyl functional polysiloxane, and the like. Examples of specific compounds are as follows: Compounds (A) to (D).

_{^{CH 2 = CH- (R 1 R}} 2 Si) n-CH = CH 2 (A)
(R ¹ and R ² are alkyl groups having 1 to 10 carbon atoms)

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

  As described above, the refractive index of the low refractive index layer can be reduced 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. When the average particle size 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. If it is 0.5 nm or less, 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 20% by volume or less, 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.

  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 of containing a fluorine compound is that the surface of the low refractive index layer 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.

  When the antireflection film of the present invention is 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 as the low refractive index layer. However, in general, when a particle-filled composite material is closely packed with spherical particles having the same particle size (fully monodisperse), the maximum volume fraction of the particles is 0.74 according to the Horsfield packing model. From the geometrical relationship, a 26 volume% interparticle gap is inevitably generated. Therefore, ideally, when 26% by volume of binder material is added to the low refractive index layer (74% by volume of low refractive index fine particles), all the voids between the low refractive index fine particles are replaced with the binder material, which is highly filled and very Thus, a thin film having a dense low refractive index layer can be obtained. However, in reality, the fine particles have a particle size distribution, and the low refractive index fine particle / binder material interface is not wettable, and the nano-sized particle size causes a low refractive index coating agent in liquid or solvent-dried. Aggregation or the like occurs in the process. Therefore, actually, 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, and the binder material is not filled between the low refractive index fine particles. The resulting void is produced.

  The unfilled portion of the binder material in the low refractive index layer generated in the high filling 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 by adding the low refractive index fine particles has a completely trade-off relationship with wear resistance in the high filling region of the low refractive index fine particles of 70% by volume or more. It is difficult to use.

  When the low refractive index fine particles are used in the antireflection film of the present invention, the low refractive index fine particles preferably 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 are composed of one or more kinds of low refractive index fine particles, and at least a hollow silica sol is preferably contained as the low refractive index fine particles. 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. As the hollow particles, those having a thin outer shell compared to the average particle diameter are preferably used, and the volume of hollow silica fine particles (including internal cavities) in the low refractive index layer is large (40 Volume% or more) is preferred. 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.

Taking the material constituting the outer shell of the hollow particles _{Specifically, SiO 2, SiOx, TiO 2} , TiOx, SnO 2, CeO 2, Sb 2 O 5, ITO, ATO, or a single material, such as _Al 2 _{O 3} 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 that the coating is performed on the hard coat layer 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, and the like to form a low refractive index layer.

  In the present invention, in order to further improve the antifouling property and fingerprint removal property of the antireflection film, it is preferable to form and coat an antifouling layer on the outermost surface of the low refractive index layer. The thickness of the antifouling layer is preferably 30 nm or less because it does not affect the optical properties. Further, the antifouling layer is formed by coating with a silicone-based or fluorine-containing compound and chemically bonding it to the surface of the low refractive index layer. In addition, as materials for forming the antifouling layer, 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 an antifouling material for forming an antifouling layer, for example, a long chain fluoroalkylsilane coating agent “XC98-B2472” manufactured by GE Toshiba Silicone is diluted to 0.2% solid content using a dilution solvent IPA (isopropanol). And after apply | coating this liquid mixture on the surface of a low-refractive-index layer with a wire bar coater # 10 so that it may become a film thickness of 15 nm, an antifouling layer can be formed by making it dry at 120 degreeC for 15 minutes. .
Moreover, fingerprint wiping property can be mentioned as performance evaluation of an antifouling layer. That is, immediately after the fingerprint is attached to the antifouling layer 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 described specifically by way of examples. The following were used as the polyester film (transparent substrate film with an easy adhesion layer):
(1) Polyethylene terephthalate (PET) film (“o3F916W” manufactured by Teijin Limited) (PET film thickness: 100 μm, easy adhesive layer thickness: 15 nm, easy adhesive layer refractive index 1.56, easy adhesive layer side reflectance : 5 .5%)
(2) Polyethylene terephthalate (PET) film (“EME-016” manufactured by Mitsubishi Chemical Polyester Film Co., Ltd. (PET film thickness: 100 μm, easy adhesion layer thickness: 90 nm, easy adhesion layer refractive index: 1.61, easy adhesion) (Layer side reflectance : 6.1%)

The hard coat layer 2 is a hard coat material obtained by dispersing various nanoparticles in an acrylic ultraviolet curable resin (“Seika Beam PET-HC15” active ingredient (solid content) 60%, manufactured by Dainichi Seika Kogyo Co., Ltd.). After preparing a composition for forming a hard coat layer, this hard coat material (mixed solution) was applied to the above-mentioned polyester film easy-adhesive film layer with a wire bar coater # 10 and dried at 80 ° C. for 1 minute. And cured by UV irradiation (600 mJ / cm ² ).

  Among the above-mentioned various nanoparticles, as the high refractive index particles, titanium oxide particles “760T” (dispersion solvent: toluene, solid content 48%) manufactured by Teika Co., Ltd. are used. ATO particles “ELCOM P-specialized product A” (dispersed solvent: MEK / toluene (4/1), solid content 30%) manufactured by Co., Ltd. were used.

  The low refractive index layer 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 is obtained by adding 356 parts by mass of methanol to 208 parts by mass of tetraethoxysilane, adding 18 parts by mass of water and 18 parts by mass of 0.01N hydrochloric acid aqueous solution, and mixing them with a disper to obtain a mixed solution. The mixed solution is used as a silicone resin (A) having a weight average molecular weight adjusted to 850 by stirring for 2 hours in a constant temperature bath at 25 ° C. Then, the following low refractive index nanoparticles (1 ) And (2) are added to the silicone resin (A) and blended so that the low refractive index nanoparticles / silicone resin have a desired volume ratio in terms of condensed solids, and then the total solid content is 1%. The low refractive index coating agent was prepared by diluting with methanol. The low refractive index coating agent was applied to the surface of the hard coat layer 2 with a wire bar coater # 10 so as to have a film thickness of 100 nm, and then dried at 120 ° C. for 15 minutes.

  As the low refractive index nanoparticles (1), hollow silica IPA (isopropanol) dispersion sol (Thruria CS-60IPA, solid content 20% by weight, manufactured by Catalyst Kasei Kogyo Co., Ltd.) was used. As the low refractive index nanoparticles (2), organosilica sol (IPA-ST, solid content 30% by weight, manufactured by Nissan Chemical Co., Ltd.) was used.

Example 1
A hard coat material in which 30% by mass of titanium oxide particles (760T) was dispersed was coated on o3F916W on a PET film to obtain a cured film (hard coat layer 2) having a thickness of 3 μm. A low refractive index coating agent in which 60% by volume of CS-60IPA was dispersed in a silicone resin (A) matrix was then coated with a wire bar coater to a film thickness of about 100 nm. Thereafter, the film was cured at 120 ° C. for 15 minutes to prepare an antireflection film.

(Example 2)
An antireflection film was prepared in the same manner as in Example 1 except that EME016 was used for the PET film.

(Example 3)
An antireflection film was prepared in the same manner as in Example 2 except that a hard coat material in which 80% by mass of titanium oxide particles (760T) were dispersed was used.

Example 4
An antireflection film was prepared in the same manner as in Example 2 except that titanium oxide particles (760T) were 30% by mass and ATO particles (ELECOM-P special product A) were 50% by mass as particles dispersed in the hard coat material. did.

(Example 5)
An antireflection film was prepared in the same manner as in Example 2 except that a low refractive index coating agent containing 40% by volume of hollow silica particles (CS60IPA) was used.

(Example 6)
An antireflection film was prepared in the same manner as in Example 2 except that 60% by volume of organosilica sol (IPA-ST) was blended in the low refractive index coating agent instead of the hollow silica particles.

(Example 7)
After the hard coat layer (first hard coat layer) described in Example 2 was formed on the PET film EME016, a hard coat material in which 40% by mass of titanium oxide particles (760T) were dispersed was coated, and an optical film thickness of 560 nm was applied. Two hard coat layers were obtained. A low refractive index coating agent in which 60% by volume of CS-60IPA was dispersed in a silicone resin (A) matrix was then coated with a wire bar coater to a film thickness of about 100 nm. Thereafter, the film was cured at 120 ° C. for 15 minutes to prepare an antireflection film.

(Example 8)
After the first hard coat layer was formed as described in Example 2, a hard coat material in which 70% by mass of titanium oxide particles (760T) were dispersed was coated to obtain a second hard coat layer having an optical film thickness of 140 nm. An antireflection film was prepared in the same manner as in Example 7.

Example 9
An antireflection film was prepared in the same manner as in Example 8 except that the second hard coat layer was coated so that the optical film thickness was 560 nm.

(Example 10)
An antifouling material was coated on the antireflection film prepared in Example 2 with a wire bar coater so as to have a film thickness of about 15 nm to form an antifouling layer. Thereafter, the film was cured at 120 ° C. for 15 minutes to prepare an antireflection film. As the antifouling material, XC98-B2472 (manufactured by GE Toshiba Silicone, product number: XC98-B2472, long-chain fluoroalkylsilane coating agent) was used.

(Comparative Example 1)
An antireflection film in which the hard coat layer 2 and the low refractive index layer 3 were laminated was produced in the same manner as in Example 1 except that o3PF8W was used for the PET film.

(Comparative Example 2)
An antireflection film was prepared in the same manner as in Example except that titanium oxide was not contained in the hard coat material.

(Comparative Example 3)
Using a hard coat material not containing titanium oxide on the PET film o3PF8W, after forming the first hard coat layer, a hard coat material in which 40% by mass of titanium oxide particles (760T) are dispersed is coated, and an optical film thickness of 140 nm is applied. A second hard coat layer was obtained. A low refractive index coating agent in which 60% by volume of CS-60IPA was dispersed in a silicone resin (A) matrix was then coated with a wire bar coater to a film thickness of about 100 nm. Thereafter, the film was cured at 120 ° C. for 15 minutes to prepare an antireflection film.

  The evaluation results of the antireflection films obtained in Examples 1 to 10 and Comparative Examples 1 to 3 are shown in Tables 1 and 2. Each evaluation method (see above for fingerprint removability) is as follows.

  Appearance interference unevenness: After black-painting the back surface of the A4 size sample, the appearance characteristics are visually observed under a three-wavelength fluorescent lamp.

Luminous reflectance: A spectrophotometer U-4100 manufactured by Hitachi High-Technologies Corporation is used, and the back surface of the sample is painted black according to JIS R-3106, and then measured with regular reflection of 5 degrees.
Spectral reflectance (450 nm, 650 nm): After using the spectrophotometer U-4100 manufactured by Hitachi High-Technologies Corporation to blacken the back of the sample based on JIS R-3106, 5 degrees at 450 nm and 650 nm Measure by specular reflection.

  Adhesiveness (cross-cut tape test): The sample is subjected to a cross-cut tape peeling test in accordance with JIS D0202-1988. Using cellophane tape (“CT24”, manufactured by Nichiban Co., Ltd.), the film is adhered to the film with the belly of the finger and then peeled. 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.

From the results of the above Examples and Comparative Examples, in the antireflection film in which a hard coat layer having a refractive index of 1.58 to 1.85 is formed on the surface of the polyester film, the polyester film with an easy adhesion layer on the side in contact with the hard coat layer By using a polyester film having a reflectance of 6.1 % or more and 8% or less , reflection interference unevenness can be suppressed, the appearance characteristics can be improved and the antireflection performance can be improved, and the hard coat layer can be peeled off. Can be reduced.

It is sectional drawing which shows an example of embodiment of this invention.

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

Claims (9)

Comprising a polyester film, and said polyester film on the formed adhesive layer, said adhesive layer on the formed hard coat layer, a low refractive index layer formed on the hard coat layer An anti-reflection film,
The refractive index of the hard coat layer is 1.58 to 1.85,
The easy adhesion layer has a film thickness of 5 nm to 80 nm and a refractive index of 1. 61 to 1.75,
8% der less reflectivity of 6.1% or more of the adhesive layer side of the polyester film the adhesive layer is formed is,
Antireflection film refractive index of the low refractive index layer and wherein 1.30 to 1.45 der Rukoto.   The hard coat layer comprises high refractive index particles made of an oxide containing at least one selected from the group consisting of titanium, aluminum, cerium, yttrium, zirconium, niobium, and antimony. Item 2. The antireflection film according to Item 1.   The antireflection film according to claim 1, wherein the hard coat layer contains an antistatic agent.   4. The antireflection film according to claim 3, wherein the antistatic agent is a conductive nanoparticle made of an oxide containing at least one selected from the group consisting of indium, zinc, tin, and antimony. The sheet resistance of the hard coat layer is 10 ¹⁵ Ω / □ or less, and the antireflection film according to any one of claims 1 to 4.   The antireflective film according to claim 1, wherein a refractive index of the low refractive index layer is 1.30 to 1.45.   Further, a second hard coat layer having a refractive index of 1.60 to 2.00 is provided between the hard coat layer and the low refractive index layer, and the refractive index of the second hard coat layer is The antireflection film according to claim 1, wherein the antireflection film has a refractive index higher than that of the coat layer.   8. The antireflection film according to claim 7, wherein the optical thickness of the second hard coat layer is from 80 nm to 600 nm.   The antireflection film according to claim 1, further comprising an antifouling layer on the low refractive index layer.

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