JP2010032734A - Antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film which is excellent in appearance characteristic and can improve antireflection performance by reducing reflection interference irregularity. <P>SOLUTION: The antireflection film includes: a surface side easy adhesion layer 2 and a hard coat layer 3 disposed in this order on the surface of a polyester film 1; and a back surface side easy adhesion layer 4 formed on the back surface of the polyester film 1. Therein, the refractive index of the hard coat layer 3 is 1.58 to 1.85, and an optical film thickness of the back surface side easy adhesion layer 4 is 110 to 170 nm. <P>COPYRIGHT: (C)2010,JPO&INPIT

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.

  Polyester films, especially biaxially stretched films of polyethylene terephthalate and polyethylene naphthalate, have excellent mechanical properties, heat resistance, chemical resistance, etc., so they are used for magnetic tapes, ferromagnetic thin film tapes, packaging films, and electronic parts. It is widely used as a material for films, electrical insulating films, laminating films, films stuck on the surface of displays, protective films for various members, and the like. In particular, for display applications, base films such as prism lens sheets, touch panels, and backlights, which are members of liquid crystal display devices, antireflection films for televisions, antireflection films used for front optical filters for plasma televisions, Applications include infrared cut film and electromagnetic shielding film base film.

  A base film used for an optical film such as an antireflection film is required to have high permeability and easy adhesion to a coating layer. That is, the base film has a hard coat layer material, an adhesive material, a reflective material for forming a hard coat layer provided for surface protection, for example, in order to secure the performance as an optical film and enhance the function. Although preventive treatment materials and other coating materials are applied, excellent easy adhesion to such coating materials may be required.

  However, a normal polyester film has high crystallinity, and it has been generally difficult to ensure adhesion with the coating material. Therefore, for example, in order to ensure easy adhesion with the hard coat layer, the method of coating the easy adhesion layer on the surface of the polyester film is based on a gas phase surface treatment method such as corona treatment or flame treatment, or by application of a primer or the like. Chemical surface treatment methods are used. In particular, since a PET film used for display applications requires high transparency and adhesion, it is common to use a type in which an easy-adhesion layer having a thickness of nanometer order is applied (for example, (See Patent Document 1).

  When a polyester film coated with such an easy-adhesion layer is used, high transparency and adhesion with the hard coat layer can be secured as described above, and the blocking resistance of the polyester film is improved. be able to.

However, when used for an optical film such as an antireflection film, the interface reflection increases due to a refractive index mismatch between the easy-adhesion layer and the polyester film, and between the easy-adhesion layer and the hard coat film. Was produced. In addition, for the easy-adhesion layer located on the opposite side of the hard coat layer, the interface reflection between the easy-adhesion layer and the polyester film and between the easy-adhesion layer and the constituent layers (adhesive layer, etc.) is also increased. However, the problem of an increase in reflectivity has occurred.
Japanese Patent Laid-Open No. 9-220791

  The present invention has been made in view of the above points, and an object of the present invention is to provide an antireflection film that reduces reflection interference unevenness, has excellent appearance characteristics, and can obtain high antireflection performance. .

  In the antireflection film according to claim 1 of the present invention, the front-side easy-adhesion layer 2 and the hard coat layer 3 are provided in this order on the surface of the polyester film 1, and the back-side easy-adhesion layer 4 is provided on the back surface of the polyester film 1. In the antireflection film provided, the refractive index of the hard coat layer 3 is 1.58 to 1.85, and the optical film thickness of the back-side easy-adhesion layer 4 is 110 to 170 nm. Is.

  The invention according to claim 2 is characterized in that, in claim 1, the refractive index of the back-side easy-adhesion layer 4 is 1.45 to 1.65.

  The invention according to claim 3 is characterized in that in claim 1 or 2, the reflectance of the polyester film 1 is 4% or more.

  The invention according to a fourth aspect is characterized in that, in any one of the first to third aspects, the film thickness of the front-side easy-adhesion layer 2 is 5 to 80 nm.

  The invention according to claim 5 is characterized in that, in any one of claims 1 to 4, the refractive index of the front-side easy-adhesion layer 2 is 1.58 to 1.75.

  The invention according to claim 6 is the hard coat layer according to any one of claims 1 to 5, wherein at least one oxide selected from titanium, aluminum, cerium, yttrium, zirconium, niobium, and antimony is used as the high refractive index particles. 3 is contained.

  The invention according to claim 7 is characterized in that, in any one of claims 1 to 6, the hard coat layer 3 has an antistatic property.

  The invention according to claim 8 is the hard coat layer 3 containing at least one oxide selected from indium, zinc, tin, and antimony as conductive nanoparticles according to any one of claims 1 to 7. It is characterized by this.

The invention according to claim 9 is characterized in that, in any one of claims 1 to 8, the sheet resistance of the hard coat layer 3 is 10 ¹⁵ Ω / □ or less.

  The invention according to a tenth aspect is that in any one of the first to ninth aspects, the low refractive index layer 5 having a refractive index of 1.30 to 1.45 is provided on the surface of the hard coat layer 3. It is a feature.

  The invention according to claim 11 is characterized in that, in claim 10, an antifouling layer 6 is provided on the surface of the low refractive index layer 5.

  According to the antireflection film of the first aspect of the present invention, it is possible to reduce reflection interference unevenness, to have excellent appearance characteristics and to obtain high antireflection performance.

  According to the invention which concerns on Claim 2, interface reflection can be reduced and antireflection performance can be obtained still higher.

  According to the invention of claim 3, it is possible to reduce reflection interference unevenness, further improve the appearance characteristics, and obtain higher antireflection performance.

  According to the invention which concerns on Claim 4, the increase in a reflectance and the deterioration of interference nonuniformity can be prevented, ensuring the adhesiveness of a polyester film and a hard-coat layer.

  According to the fifth aspect of the invention, the difference between the refractive index of the front-side easy-adhesion layer and the refractive index of the polyester film and the hard coat layer is reduced, thereby increasing the reflectance as an antireflection film and causing interference unevenness. Deterioration can be prevented.

  According to the invention of claim 6, 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 seventh aspect of the present invention, the hard coat layer can be prevented from being charged by static electricity or the like, and dust can be made difficult to adhere.

  According to the invention which concerns on Claim 8, 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 ninth aspect of the invention, the antistatic property of the hard coat layer can be improved.

  According to the tenth 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 eleventh 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 the antireflection film shown in FIG. 1A, the polyester film 1 is used as a transparent substrate. A front-side easy-adhesion layer 2 and a back-side easy-adhesion layer 4 are provided on both front and back surfaces of the polyester film 1, respectively. A hard coat layer 3 is further provided on the surface of the front-side easy-adhesion layer 2. FIG.1 (b) is sectional drawing which shows the state which affixed the said antireflection film on structural layers 7, such as an adhesion layer.

  FIG. 2 is a cross-sectional view showing another example of the antireflection film according to the present invention. In the antireflection film shown in FIG. 2A, a low refractive index layer 5 is provided on the surface of the hard coat layer 3. FIG. 2B is a cross-sectional view showing a state in which the antireflection film having the low refractive index layer 5 provided on the outermost surface is attached to the constituent layer 7 such as an adhesive layer.

  FIG. 3 is a cross-sectional view showing another example of the antireflection film according to the present invention. In the antireflection film shown in FIG. 3A, the antifouling layer 6 is provided on the surface of the low refractive index layer 5. FIG. 3B is a cross-sectional view showing a state in which the antireflection film having the antifouling layer 6 provided on the outermost surface is attached to the constituent layer 7 such as an adhesive layer.

  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 3 and the pressure-sensitive adhesive, etc. on the polyester film 1, as necessary, 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 the blocking resistance in a roll state, slipperiness, and adhesion with the hard coat layer 3 while maintaining high transparency with a haze of 3% or less, the surface side of nanometer order A polyester film 1 coated with an easy adhesion layer 2 is generally used conventionally. However, when the polyester film 1 coated with such a surface-side easy-adhesion layer 2 is used, the refractive index of the surface-side easy-adhesion layer 2 is generally different from the refractive index of the polyester film 1.

  First, for the back-side easy-adhesive layer 4, the interface with the polyester film 1, and when the constituent layer 7 such as an adhesive layer or other acrylic resin film is provided on the opposite side, the interface with the constituent layer 7, the total There are two types of interface reflections, which increase the reflectivity. In order to solve this problem, it is desirable that the refractive index of the back-side easy-adhesion layer 4 takes an intermediate value between the refractive index of the polyester film 1 and the refractive index of the constituent layer 7, and the optical film thickness is The reflectance can be reduced most at 140 nm. Specifically, it is preferable that the refractive index of a back surface side easily bonding layer is 1.45-1.65. Thereby, interface reflection can be reduced and antireflection performance can be obtained further higher. Usually, the constituent layer 7 is often provided with an adhesive layer or other acrylic resin film (refractive index n = 1.45 to 1.65), for example, when an adhesive layer (n = 1.54) is provided. When the polyester film 1 is a PET film (n = 1.69), the reflectance is reduced most when the refractive index of the back-side easily adhesive layer 4 is 1.62 and the optical film thickness is 140 nm (actual film thickness 86 nm). can do. In the following, simply referring to “film thickness” means an actual film thickness (physical film thickness).

  Next, with respect to the front side easy-adhesion layer 2, when the difference in refractive index from the hard coat layer 3 is large, appearance interference non-uniformity occurs due to the non-uniformity of the film thickness of the front side easy-adhesion layer 2 and the hard coat layer 3. There was a problem such as doing. If the surface side easy-adhesion layer 2 is provided on the surface of the polyester film 1 and further the hard coat layer 3 having a refractive index of 1.58 to 1.85 is provided on the surface of the surface side easy-adhesion layer 2, optically hard There is a possibility that reflection occurs at the interface of the coat layer 3 / surface-side easy-adhesion layer 2 and surface-side easy-adhesion layer 2 / polyester film 1 and deteriorates the reflectance characteristics and interference unevenness characteristics of the antireflection film. In order to suppress this reflection, it is necessary to exclude an optical adverse effect due to the surface-side easy-adhesion layer 2. The reflectance of the polyester film 1 provided with the surface-side easy-adhesion layer 2 is such that the refractive index of the surface-side easy-adhesion layer 2 used is higher than the refractive index of the polyester film 1 (in the case of PET film, n = 1.69). As it becomes smaller and the film thickness of the front-side easy-adhesion layer 2 approaches 100 nm, it becomes smaller. On the other hand, when the optical adverse effect of the front-side easy-adhesion layer 2 is excluded, the reflectance approaches 6.5% of the polyester film 1 alone. In the present invention, in view of such a problem, the polyester film 1 to be used has a reflectance of 4% or more (upper limit is 9%) of the polyester film provided with the surface-side easy-adhesion layer 2 in contact with the hard coat layer 3. ), And the adverse effect of the surface-side easy-adhesion layer 2 is excluded. Thus, when the reflectance of the polyester film 1 is 4% or more, the reflection interference unevenness can be reduced, the appearance characteristics can be further improved, and the antireflection performance can be further enhanced.

  In order to increase the reflectance of the polyester film 1 provided with the surface side easy adhesion layer 2, it is preferable to control the film thickness of the surface side easy adhesion layer 2 to 5 to 80 nm. Thereby, while ensuring the adhesiveness of the polyester film 1 and the hard-coat layer 3, the increase in a reflectance and the deterioration of interference nonuniformity can be prevented. However, if the film thickness of the surface-side easy-adhesion layer 2 is less than 5 nm, there is a possibility that the entire surface of the polyester film 1 cannot be uniformly coated with the material forming the surface-side easy-adhesion layer 2. It may be difficult to ensure stable adhesion between the hard coat layer 3 and the hard coat layer 3. Conversely, when the film thickness of the surface-side easy-adhesion layer 2 exceeds 80 nm, reflection on the surface-side easy-adhesion layer 2 becomes large, and problems such as an increase in reflectance as an antireflection film and deterioration of interference unevenness may occur. There is. Moreover, in order to raise the reflectance of the polyester film 1 in which the surface side easily bonding layer 2 was provided, it is preferable to make the refractive index of the surface side easily bonding layer 2 into 1.58-1.75. As a result, the difference between the refractive index of the front-side easy-adhesion layer 2 and the refractive index of the polyester film 1 and the hard coat layer 3 is reduced, thereby preventing an increase in the reflectance as an antireflection film and a deterioration in interference unevenness. It is something that can be done. However, if the refractive index of the front-side easy-adhesion layer 2 is less than 1.58 or exceeds 1.75, the difference between the refractive index of the hard coat layer 3 and the refractive index of the polyester film 1 increases, and the reflection There is a possibility that problems such as an increase in reflectance as a prevention film and deterioration of interference unevenness may 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 3 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. In addition, the occurrence of cracks in the low refractive index layer 5 (described later) due to the bending of the polyester film 1 is suppressed to improve the mechanical strength of the antireflection film.

  In the present invention, the pencil hardness of the hard coat layer 3 is preferably H or higher, more preferably 2H or higher. In order to improve the hardness of the hard coat layer 3, a reactive curable resin, that is, thermosetting is used. The hard coat layer 3 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 3).

  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 3 is formed using a thermosetting resin, the thermosetting resin is applied to the surface of the polyester film 1 via the surface-side easy-adhesion layer 2 and then dried and cured by heating. Is preferred.

  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 3 is formed using an ultraviolet curable resin that undergoes a photopolymerization reaction, the ultraviolet curable resin is applied to the surface of the polyester film 1 via the surface-side easy-adhesion layer 2, dried, and then irradiated with ultraviolet rays. It is preferable to cure by.

  The hard coat layer 3 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 3 is 1-2 micrometers or more.

The refractive index of the hard coat layer 3 composed of the above components is usually about 1.49 to 1.52, but in the present invention, the hard coat layer 3 contains high refractive index particles to increase the refractive index and prevent reflection. In order to improve performance, high refractive index particles, that is, ultrafine particles of a metal or metal oxide having a high refractive index can be added to the material of the hard coat layer 3. 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 preferred refractive index of the hard coat layer 3 for lowering the reflectance is 1.58 to 1.85, and the present invention has this refractive index. In order to form the hard coat layer 3, 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 3. As the ultrafine particles of the high refractive index metal or metal oxide, one or two or more oxide particles 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 3 as high refractive index particles, the refractive index of the hard coat layer 3 can be increased, and reflection interference unevenness due to the hard coat layer 3 can be reduced. In addition to excellent appearance characteristics, high antireflection performance can be obtained when the low refractive index layer 5 is provided on the surface of the hard coat layer 3.

Furthermore, it is preferable that the hard coat layer 3 has an antistatic property, which prevents the hard coat layer 3 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 3, the hard coat layer 3 may be made to contain conductive nanoparticles. This is because the hard coat layer 3 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 in the hard coat layer 3 as conductive nanoparticles, the hard coat layer 3 can be provided with conductivity, and the hard coat layer 3 having antistatic properties can 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 3 having a high refractive index and excellent antistatic properties. Specifically, the sheet resistance of the hard coat layer 3 is preferably 10 ¹⁵ Ω / □ or less, whereby the antistatic property of the hard coat layer 3 can be improved. In addition, since the antistatic property improves as the sheet resistance of the hard coat layer 3 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 3 is Substantially 10 ⁶ Ω / □ or more. Moreover, the sheet resistance value of the hard coat layer 3 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 3. Can be adjusted.

  In addition, as shown in FIG. 2, before forming the low refractive index layer 5 by applying a low refractive index coating agent for forming the low refractive index layer 5 on the surface of the hard coat layer 3, It is preferable to perform a surface treatment of the coat layer 3. By performing this surface treatment, the wettability and adhesion between the hard coat layer 3 and the low refractive index layer 5 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 5 is a layer having a refractive index smaller than that of the polyester film 1 and the hard coat layer 3, and is formed by applying a low refractive index coating agent to the surface of the hard coat layer 3. be able to. The low refractive index layer 5 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. The thickness d of the low refractive index layer 5 is preferably nd = λ / 4, where n is the refractive index of the low refractive index layer 5 and λ is the wavelength of incident light. Specifically, the thickness of the low refractive index layer 5 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 Dimethyl butoxysilane, 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 silicon alkoxide is hydrolyzed 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, Alternatively, a mixture thereof can be mentioned. The alkoxide is dissolved in the solvent such that the alkoxide is 0.1% or more, preferably 0.1 to 10% by mass 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 mass, the formed sol film cannot sufficiently exhibit the desired characteristics, while if it exceeds 10% by mass, it becomes difficult to form a transparent homogeneous film. Moreover, in this invention, if it is less than the above solid content, it is also possible to use an 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 is excellent in coating suitability.

In the present invention, a reactive organosilicon compound or a partial hydrolyzate thereof is added to the SiO ₂ sol. Examples of the reactive organosilicon compound include, in addition to the aforementioned reactive organosilicon compound, a plurality of groups that are reactively crosslinked by heat or ionizing radiation, for example, an organosilicon compound having a molecular weight of 5000 or less having a polymerizable double bond group. It is mentioned as a preferable 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 vinyl functionality obtained by reacting these compounds. Examples include polysilane, vinyl functional polysiloxane, and the like. Examples of specific compounds are as follows.

  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 5, 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 5 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.

  The refractive index of the low refractive index layer 5 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. 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 diffusely reflected by Rayleigh scattering in the obtained low refractive index layer 5, and the low refractive index layer 5 may appear 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 5. 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, high film hardness is required for the low refractive index layer 5. 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 5 (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 5 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 5, 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 5 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 5 by adding the low refractive index fine particles has 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, and is practically used. 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 5 are composed of one or more kinds of low refractive index fine particles, and it is preferable to contain at least a hollow silica sol 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. 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 5 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. A material in the form of a material or 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 3 subjected to surface treatment 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 5 can be formed.

  In the present invention, in order to further improve the antifouling property and fingerprint removal property of the antireflection film, the antifouling layer 6 is provided on the surface of the low refractive index layer 5, and the low antireflective layer 5 is formed by the antifouling layer 6. It is preferable to coat. Since the thickness of the antifouling layer 6 does not affect the optical characteristics, it is preferable to set it to 30 nm or less. In addition, the antifouling layer 6 is formed by covering the surface of the low refractive index layer 5 with a silicone-based or fluorine-containing compound. As materials for forming the antifouling layer 6, 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 the antifouling layer 6, 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 5 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 6 can be formed. The performance evaluation of the antifouling layer 6 can include fingerprint wiping properties. That is, immediately after the fingerprint is attached to the antifouling layer 6 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 (“A1544-1-4 (100 μm film thickness, surface-side easy-adhesion layer 2: manufactured by Toyobo Co., Ltd.): optical film thickness 51 nm, refractive index 1” .60, back side easy adhesion layer 4: optical film thickness 97 to 162 nm, refractive index 1.56), polyethylene terephthalate (PET) film (Toyobo Co., Ltd. “A4300 (100 μm film thickness, front side easy adhesion layer 2) : Optical film thickness 100 nm, refractive index 1.56, back side easy adhesion layer 2: optical film thickness 100 nm, refractive index 1.56), polyethylene terephthalate (PET) film (Mitsubishi Chemical Polyester Film Co., Ltd. “O300S36U53C (100 μm Film thickness, front side easy adhesion layer 2: optical film thickness 90 nm, refractive index 1.59, back side Adhesive layer 4: using an optical film thickness 150 nm, refractive index 1.59).

The hard coat layer 3 is prepared by dispersing various nanoparticles in an acrylic ultraviolet curable resin (“SEICA BEAM PET-HC15” active ingredient (solid content) 60 mass%, manufactured by Dainichi Seika Kogyo Co., Ltd.). This hard coat material (mixed solution) was applied to the surface of the polyester film 1 with the wire bar coater # 10 through the surface-side easy-adhesion layer 2, dried at 80 ° C. for 1 minute, and then irradiated with UV ( 600 mJ / cm ² ). 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 3 of Examples 1 to 6 and Comparative Examples 1 and 2 (described later), the hard coat layer 3 Refractive index is shown.

  The low refractive index layer 5 was formed by applying a low refractive index coating agent to the surface of the hard coat layer 3. 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 3 with a wire bar coater # 10 so that the film thickness becomes 100 nm. After cloth, 120 ° C., to form a low refractive index layer 5 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], blending amounts of “CS-60IPA” and “IPA-ST” in the low refractive index layers 5 of Examples 1 to 6 and Comparative Examples 1 and 2 (described later) (both are volume%). Indicates.

  As the component layer 7, an adhesive film (manufactured by Yodogawa Paper Co., Ltd., non-carrier TD06A, adhesive layer thickness 25 μm) was used.

Example 1
A hard coat material in which 30% by mass of titanium oxide particles “760T” were dispersed was coated on the PET film “A1544-2” to obtain a hard coat layer 3 having a thickness of 3 μm. A low refractive index coating agent in which 40% by volume of “CS-60IPA” in a total amount was dispersed on the silicone resin (A) matrix was coated with a wire bar coater to a film thickness of 100 nm. Then, the antireflective film as shown in FIG. 2 was manufactured by curing at 120 ° C. for 15 minutes and providing the low refractive index layer 5.

(Example 2)
An antireflection film was produced in the same manner as in Example 1 except that “A1544-3” was used for the PET film.

(Example 3)
An antireflection film was produced in the same manner as in Example 1 except that “A1544-4” was used for the PET film.

Example 4
An antireflection film was produced in the same manner as in Example 2 except that a low refractive index coating agent containing 60% by volume of hollow silica particles (CS-60IPA) was used.

(Example 5)
An antifouling material (an antifouling material “Optool DSX” manufactured by Daikin Industries, Ltd.) on the low refractive index layer 5 of the antireflective film produced in Example 2 was formed with a wire bar coater so as to have a film thickness of about 15 nm. Coated. Thereafter, the film was cured at 120 ° C. for 15 minutes to provide an antifouling layer 6 to produce an antireflection film as shown in FIG.

(Example 6)
An antireflection film was produced in the same manner as in Example 1 except that “O300S36U53C” was used for the PET film.

(Comparative Example 1)
A hard coat material in which 30% by mass of titanium oxide particles “760T” were dispersed was coated on the PET film “A1544-1” to obtain a hard coat layer 3 having a thickness of 3 μm. A low refractive index coating agent in which 40% by volume of “CS-60IPA” in a total amount was dispersed on the silicone resin (A) matrix was coated with a wire bar coater to a film thickness of 100 nm. Then, the antireflective film was manufactured by hardening on 120 degreeC and the conditions for 15 minutes, and providing the low-refractive-index layer 5. FIG.

(Comparative Example 2)
An antireflection film was produced in the same manner as in Example 1 except that “A4300” was used as the PET film.

  The evaluation results of the antireflection films (samples) of Examples 1 to 6 and Comparative Examples 1 and 2 are shown in [Table 1] below. Each evaluation method is as follows.

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

  Average luminous reflectance: Using a spectrophotometer “U-4100” manufactured by Hitachi High-Technologies Corporation, the back surface of the sample was painted black based on JIS R-3106, and then measured with regular reflection of 5 degrees.

  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.

  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.

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 another example of the antireflection film concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polyester film 2 Front side easily bonding layer 3 Hard-coat layer 4 Back side easily bonding layer 5 Low refractive index layer 6 Antifouling layer

Claims (11)

  In the antireflection film formed by providing the surface side easy-adhesion layer and the hard coat layer in this order on the surface of the polyester film, and providing the back side easy-adhesion layer on the back side of the polyester film, the refractive index of the hard coat layer is 1 An antireflection film having a thickness of .58 to 1.85 and an optical film thickness of the back-side easy-adhesion layer of 110 to 170 nm.   The refractive index of a back surface side easily bonding layer is 1.45 to 1.65, The antireflection film of Claim 1 characterized by the above-mentioned.   The antireflection film according to claim 1, wherein the polyester film has a reflectance of 4% or more.   The antireflection film according to any one of claims 1 to 3, wherein the surface-side easy-adhesion layer has a thickness of 5 to 80 nm.   The antireflective film according to any one of claims 1 to 4, wherein the refractive index of the front-side easy-adhesion layer is 1.58 to 1.75.   6. The hard coat layer 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 antireflection film as described in 1.   The antireflection film according to any one of claims 1 to 6, wherein the hard coat layer has antistatic properties.   8. The antireflection film according to claim 1, wherein at least one oxide selected from indium, zinc, tin, and antimony is contained in the hard coat layer as conductive nanoparticles. . 9. The antireflection film according to claim 1, wherein the hard coat layer has a sheet resistance of 10 ¹⁵ Ω / □ or less.   The antireflection film according to claim 1, wherein a low refractive index layer having a refractive index of 1.30 to 1.45 is provided on the surface of the hard coat layer.   The antireflection film according to claim 10, wherein an antifouling layer is provided on the surface of the low refractive index layer.

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