JP2009015289A - Antireflection film and display front plate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film having less interference fringes, excelling in antireflection performance and having high scratch resistance without having a primer layer for improving adhesion between a polyester base and a hard coat layer, and to provide a display front plate using the antireflection film. <P>SOLUTION: The antireflection film includes the polyester base 10 and an antireflection layer disposed on one main surface side 10a of the polyester base 10 by a wet coating method. The antireflection layer includes, from the polyester base 10 side, a hard coat layer 11 and a low refractive index layer 12 disposed above the hard coat layer. The hard coat layer 11 is provided directly on the polyester base 10. The hard coat layer contains a metal oxide, in a ratio of 20 vol% to 42 vol%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an antireflection film having an antireflection layer and a display front plate using the same.

  In recent years, development of high-definition and large-screen displays typified by liquid crystal displays and plasma display panels (PDP) has been rapidly progressing. In order to improve the visibility of the display surface of the display, it is necessary to dispose an antireflection layer having an antireflection function on the surface in order to prevent reflection of external light such as a fluorescent lamp on the screen.

  The antireflection layer is formed by depositing or sputtering inorganic metal on the display surface, so-called dry coating, and applying low-refractive-index materials, etc., to the substrate in liquid form, such as a solution or dispersion, and then drying. There is known a wet coating method for producing a film having an antireflection function by curing in accordance with the above. With the recent increase in size of displays, roll-to-roll (roll-to-roll) wet coating methods that are inexpensive and easy to handle are becoming mainstream. In other words, the price competition for televisions using high-definition and large-screen displays typified by liquid crystal displays and plasma display panels (PDP) is fierce internationally, and is produced by vapor deposition or sputtering of inorganic metals. Poor nature and cost. Wet coating methods that are inexpensive and easy to accommodate upsizing are becoming mainstream, but further reduction in costs is always required for antireflection films manufactured by the wet coating method. Therefore, even in the wet coating method, when manufacturing an optical film having the same function, for example, an antireflection film, an antireflection film that can reduce the number of manufacturing steps, specifically, a layer to be formed and a processing step are required. An antireflection film that can be manufactured in a small amount and has the necessary functions and quality is advantageous in terms of cost reduction.

  The antireflection layer made by the wet coating method has a hard coat layer for increasing the hardness of the substrate itself on the transparent substrate film, and a single layer or a plurality of layers having different refractive indexes on the hard coat layer. There is an antireflection film formed with front and back film thicknesses (Patent Document 1).

  As the transparent base film, a polyester resin film, particularly a biaxially stretched film of polyethylene terephthalate (PET) is often used. The biaxially stretched PET film has transparency, and has excellent mechanical properties, flame resistance, chemical resistance, and the like, and therefore, the growth in demand as a base film for the above antireflection film is remarkable.

  However, it is generally difficult for such a polyester base material to maintain good adhesion with the antireflection layer.For example, when a biaxially stretched PET film is used as the transparent base material, the adhesion between the PET film and the antireflection layer is reduced. In order to enhance, a primer layer (also referred to as an anchor coat layer) for imparting easy adhesion, also referred to as an easy adhesion layer, on the surface of the PET film. In most cases, it is simply abbreviated as “primer layer”. That is, when an antireflection layer is formed on a PET film by a wet coating method, in actual production, for example, [0032] in Patent Document 2 and [0077] to [0079] in Patent Document 3 described later, Patents As described in [0024] of Document 4, [0004] of Patent Document 5, [0003] of Patent Document 6, and the like, at least on the main surface side of the PET film on which the antireflection layer is formed, an easy adhesion layer is provided. Currently, a primer layer is formed or a PET film on which the primer layer is formed is used.

  However, in the antireflection layer where the relationship between the film thickness and refractive index of each layer provided on the base material is very important, the primer layer also has a great influence on the antireflection performance. It is necessary to design in consideration of the three refractive indexes and film thicknesses of the layers (Patent Documents 2 to 4).

  However, this optical design is difficult and it is difficult to suppress the occurrence of interference spots. Further, providing a primer layer in addition to the hard coat layer and the low refractive index layer increases the number of manufacturing steps, making it difficult to meet the low cost requirements of the market.

  As a method other than providing a primer layer, an easy-adhesion surface pretreatment such as corona treatment or plasma treatment on a polyester substrate ("Easy-adhesion surface pretreatment" means that a new layer such as a primer layer is separately formed. It has also been proposed to improve the adhesion by modifying the surface of the base material, but it is difficult to achieve sufficient adhesion only by corona treatment or plasma treatment (patented) Reference 5).

On the other hand, by using a specific resin for forming the hard coat layer, it has been proposed to improve the adhesion with a polyester resin base material without providing a primer layer (Patent Document 6). However, this method does not provide sufficient adhesion between the substrate and the hard coat layer.
JP 2002-200690 A Japanese Patent Laid-Open No. 2003-177209 JP 2004-345333 A JP 2006-258897 A JP 2006-235125 A JP 2005-196065 A

  Therefore, the present invention can ensure the adhesion between the polyester substrate and the antireflection layer even when using a polyester substrate that does not have a primer layer on the main surface side where the antireflection layer is formed. An object of the present invention is to provide an antireflection film having excellent antireflection performance by preventing the occurrence of interference spots, and a display front plate using the antireflection film.

(1) In order to solve the above problems, an antireflection film of the present invention comprises a polyester base material and an antireflection film disposed on one main surface side of the polyester base material by a wet coating method. Because
The antireflection layer includes a hard coat layer and a low refractive index layer disposed above the hard coat layer from the polyester substrate side,
The hard coat layer is provided directly on the polyester substrate,
The hard coat layer contains a metal oxide, and the ratio of the metal oxide is 20% by volume to 42% by volume.

  (2) In the antireflection film as described in the above item (1), the main surface of the polyester base on the side where the antireflection layer is disposed is a polyester base that is not subjected to an easy adhesion surface pretreatment. Is preferred.

  (3) In the antireflection film according to (1) or (2), the antireflection layer is peeled off from the polyester base material in a substrate eye peeling test performed based on JIS K5600-5-6. An antireflection film that is not recognized is preferred.

  (4) In the antireflection film described in any one of the above items (1) to (3), the maximum value of the difference in reflectance amplitude at 380 nm to 780 nm of the antireflection film is 1.0% or less. It is preferable that

  (5) In the antireflection film according to any one of (1) to (4), it is preferable that a near-infrared absorbing layer is disposed on the other main surface side of the polyester base material. .

  (6) Moreover, the display front plate of the present invention is characterized in that the antireflection film described in any one of the above items (1) to (5) is disposed on a substrate.

  (1) According to the present invention, it is possible to ensure the adhesion between the polyester base material and the antireflection layer, further prevent the occurrence of interference spots, and provide an antireflection film having excellent antireflection performance. In addition, since the hard coat layer is directly provided on the polyester base material without using a primer layer for easy adhesion, it is not necessary to form a primer layer, so that it is an inexpensive antireflection film. Can be provided. And even if there is no said primer layer, the adhesiveness of a polyester base material and an antireflection layer is securable.

(2) Moreover, in the antireflection film according to (1), the main surface of the polyester base on the side where the antireflection layer is disposed is a polyester base that has not been subjected to an easy adhesion surface pretreatment. By adopting a preferred embodiment of the present invention, the adhesion between the polyester base material and the antireflection layer can be ensured even if the easy adhesion surface pretreatment is not performed, so the easy adhesion surface pretreatment may be omitted. Thus, an inexpensive antireflection film can be provided. (In the present invention according to claim 1, it is not excluded to use a polyester base material that has been subjected to an easy adhesion surface pretreatment.)
(3) Moreover, in the antireflection film as described in the above item (1) or (2), the antireflection layer is peeled off from the polyester base material in a substrate eye peeling test performed based on JIS K5600-5-6. By adopting a preferred embodiment of the present invention in which no anti-reflection is observed, it is possible to provide an antireflection film excellent in quality reliability in which the antireflection layer does not peel off.

  (4) Further, in the antireflection film according to any one of the above items (1) to (3), the maximum value of the difference in reflectance amplitude at 380 nm to 780 nm of the antireflection film is 1.0%. By setting it as the preferable aspect of this invention which is the following, the antireflection film with few generation | occurrence | production of interference spots can be provided.

  (5) Moreover, in the antireflection film as described in any one of the above items (1) to (4), a book in which a near-infrared absorbing layer is disposed on the other main surface side of the polyester base material. According to a preferred aspect of the invention, the antireflection film provided with the near-infrared absorbing layer is provided on the front surface of a plasma display panel (PDP) used as a display panel for various electronic devices including large TVs. Therefore, it is possible to further exert a function as a filter for shielding unnecessary near infrared rays generated from the front surface of the PDP while using these electronic devices, and malfunction of peripheral electronic devices such as TVs and air conditioners due to leakage of the near infrared rays. Therefore, it is possible to provide an antireflection film which is suitable for preventing the problem of causing an antireflection and has an antireflection function.

  (6) Moreover, since the antireflection film as described in any one of said (1)-(5) terms is arrange | positioned on the board | substrate, the display front board of this invention is cheaper. A front plate for a display can be provided, and a front plate for a display that exhibits functions corresponding to the items (1) to (5) can be provided with respect to the antireflection film layer.

  The polyester base material used in the antireflection film of the present invention preferably has a light transmittance in the visible light region of 80% or more, more preferably 88% or more. The haze is preferably 2.0% or less, and more preferably 1.0% or less. Typical examples of polyester base materials include polyethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate, which are particularly inexpensive but have transparency and excellent mechanical properties. A biaxially stretched film of polyethylene terephthalate (PET) is preferred because it has both flame resistance (properity to burn) and chemical resistance. The thickness of the substrate is usually about 10 to 500 μm. In addition, additives, such as antioxidant, a flame retardant, a heat-resistant agent, a ultraviolet absorber, and a lubricant, may be added to resin which comprises the said polyester base material.

  The coating material for forming the hard coat layer may be prepared by combining the following ionizing radiation curable resin, conductive and / or non-conductive metal oxide fine particles, photoinitiator, solvent, etc. You may use what was already mixed and prepared and inked. In order to adjust the hard coat layer coating material using the following components, a dispersion treatment may be performed according to a general method for adjusting the coating liquid.

  The refractive index of the hard coat layer needs to be designed in consideration of the relationship of the refractive index with the substrate. For example, the refractive index of a PET base material, which is a polyester base material, is about 1.66. If the refractive index of the hard coat layer provided on the surface is greatly different from this, interference spots may be generated. Usually, interference spots occur when the difference in refractive index between the hard coat layer and the substrate film is ± 0.03 or more. Therefore, the refractive index of the hard coat layer is preferably set to 1.60 to 1.70. By adding a metal oxide having a large refractive index, the refractive index of the hard coat layer becomes close to that of the base film. One kind or two or more kinds of metal oxides may be used.

  In addition, in the antireflection film of the present invention, the antireflection film with less occurrence of interference spots is obtained by setting the maximum value of the difference in reflectance at 380 nm to 780 nm of the antireflection film to 1.0% or less. Can be provided. For this purpose, as described above, the difference between the refractive index of the polyester base and the refractive index of the hard coat layer provided thereon is preferably smaller than ± 0.03, and the refractive index of the polyester base is Since it cannot be easily changed, usually, by adjusting the refractive index of the hard coat layer by selecting and combining the materials constituting the hard coat layer, that is, ionizing radiation curable resin, metal oxide fine particles, The maximum value of the difference in the amplitude of the reflectance at 380 nm to 780 nm of the obtained antireflection film can be 1.0% or less.

  By using a conductive metal oxide as the metal oxide used for the hard coat layer, the antireflection film can be provided with antistatic performance. In order to obtain a prescribed refractive index with only one type of conductive metal oxide, the content of the metal oxide in the hard coat layer may increase. Therefore, in this case, the refractive index can be increased without increasing the content of the metal oxide by using two or more types of metal oxide.

  The hard coat layer is formed using a resin containing an ionizing radiation curable resin. Thereby, a hard coat layer can be rationally formed.

Examples of the metal oxide contained in the hard coat layer include antimony-doped tin oxide (ATO), indium-doped tin oxide (ITO), phosphorus-doped tin oxide (PTO), zinc oxide (ZnO), and tin oxide (SnO). ₂ ), zirconium oxide (ZrO ₂ ), zinc antimonate (ZnSb ₂ O ₆ ) and the like can be used. The metal oxide is preferably in the form of fine particles, and the average particle diameter is preferably 100 nm or less, more preferably 50 nm or less, and particularly preferably 20 nm or less. This is because within this range, the dispersibility in the ionizing radiation curable resin is improved and the haze at the time of forming the coating film is reduced. The lower limit of the average particle diameter of the metal oxide is not particularly limited, but is preferably 2.0 nm or more from the viewpoint of conductivity and high refractive index.

  In addition, the measurement of the average particle diameter of these metal oxide particles cut | disconnects the antireflection film containing a metal oxide particle with a microtome (microtome), and TEM (transmission of 200,000 times magnification of the cut film cross-section piece) Type electron microscope) photograph is taken, and the average value of 300 particles is defined as the average particle diameter. When the photographed particles are not round but have a major axis and a minor axis, the major axis and minor axis are measured for each particle, and the average of these is calculated. This average value is measured and calculated for 300 particles, and is taken as the average particle diameter.

  And what is important in the present invention is that the content ratio of the metal oxide with respect to the hard coat layer is 20% by volume to 42% by volume, more preferably 25% to 35% by volume. By setting the content ratio of the metal oxide in the hard coat layer in the above range, the hard coat layer on the main surface of the polyester base without forming a primer layer on the main surface on the side where the hard coat layer of the polyester base is provided The adhesiveness can be made practical and strong, and the strength as a coating film can also be high. If the ratio of the metal oxide to the hard coat layer is too small, the volume shrinkage at that time is large, and it is estimated that the metal base is easily peeled off from the polyester base, while the ratio of the metal oxide to the hard coat layer is too large. In addition to reducing the strength as a coating film, it is difficult to form a coating film if it is too much. The adhesion of the hard coat layer to the surface can be made strong and practical, and the primer layer is not provided on the main surface on the side where the hard coat layer of the polyester base is provided. Can be prevented, and an antireflection film having excellent antireflection performance can be provided.

  In addition, the ratio of the said metal oxide refers to the volume of the metal oxide with respect to the volume sum total of the metal oxide and resin solid content contained in a hard-coat layer. The volume ratio can be obtained by calculation from the weight ratio between the metal oxide and the resin solid content and the specific gravity literature value of each material.

  As the ionizing radiation curable resin forming the hard coat layer, monomers having a vinyl group, a (meth) acryloyl group, an epoxy group or an oxetanyl group, prepolymers or polymers thereof can be used. These can be used alone or in combination of two or more. From the viewpoint of achieving both productivity and hardness, it is preferable to use a polyfunctional monomer or oligomer. As the polyfunctional monomer or oligomer, a polyfunctional acrylic monomer having two or more unsaturated groups or an oligomer thereof is preferably used. Furthermore, if the monomer or oligomer molecule has many bonding groups or functional groups that form hydrogen bonds, the adhesion to the polyester substrate is improved. Further, the refractive index of the hard coat layer can be increased by using a monomer or oligomer having a high refractive index such as bisphenol A-modified (meth) acrylate.

  Examples of polyfunctional acrylic monomers and oligomers include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, 1,4-cyclohexanediacrylate, and pentaerythritol tetra (meth). Acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (Meth) acrylate, 1,2,3-cyclohexanetrimethacrylate, polyurethane polyacrylate, polyester polyacrylate Esters produced from polyhydric alcohol and (meth) acrylic acid, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, vinylbenzene such as 1,4-divinylcyclohexanone and the like Derivatives and the like. These may be used alone or in combination of two or more. Of these, at least one selected from pentaerythritol triacrylate and dipentaerythritol hexaacrylate is preferable from the viewpoint of further improving the scratch resistance. Pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) The acrylate and dipentaerythritol hexa (meth) acrylate are preferable from the viewpoint of increasing the film strength. Here, "... (meth) acrylate ..." means "... acrylate ..." and / or "... methacrylate ...".

  When curing the ionizing radiation curable resin contained in the hard coat layer, when performing ultraviolet irradiation, a photopolymerization initiator is added to the coating liquid for the hard coat layer. Photopolymerization initiators include acetophenones, benzophenones, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, thiuram compounds, fluoroamine compounds Etc. are used. These can be used alone or in combination of two or more. Usually, the amount of the photopolymerization initiator used is preferably about 1 to 15% by mass with respect to the mass of the ionizing radiation curable resin to be used.

  As other components of the composition of the hard coat layer, additives such as a polymerization inhibitor, an antioxidant, a dispersant, a surfactant, a light stabilizer and a leveling agent may be added. Further, an arbitrary amount of solvent can be added as long as the film is dried after film formation by a wet coating method.

  There is no restriction | limiting in particular about the method of forming a hard-coat layer on a polyester base material, It can form by apply | coating the coating liquid containing the said material on a polyester base material. The coating method is not particularly limited, for example, a coating method such as roll coating, die coating, air knife coating, blade coating, spin coating, reverse coating, gravure coating, or printing methods such as gravure printing, screen printing, offset printing, and ink jet printing. Etc. can be used.

  The surface hardness of the hard coat layer is preferably H or higher, more preferably 2H or higher, as evaluated by a pencil hardness test specified in JIS K5600.

Further, the thickness of the hard coat layer is preferably 0.3 to 3.0 μm, and 0.3 to 2.0 μm.
Is more preferable, and 0.3 to 1.5 μm is more preferable.

  If the thickness of the hard coat layer is less than 0.3 μm, it tends to be difficult to maintain the hardness. On the other hand, if the thickness of the hard coat layer exceeds 3.0 μm, cracking, curling (warping of the film) occurs, or the total light transmittance of the antireflection film tends to decrease. In addition, the volume shrinkage of the ionizing radiation curable resin increases, and the hard coat layer tends to be peeled off from the polyester substrate. Accordingly, the thickness of the hard coat layer is preferably within the above range.

  The low refractive index layer disposed on the hard coat layer has an optical film thickness, which is the product of the refractive index and the film thickness, of λ / 4 (λ: the wavelength of human visible light. A high light wavelength is often set to 550 nm), and it is preferable that the reflectance is lower. Further, the greater the difference between the refractive index of the low refractive index layer and the refractive index of the hard coat layer, the better the antireflection property. Furthermore, when the low refractive index layer is positioned on the outermost surface of the antireflection film of the present embodiment (that is, when no other functional layer is provided on the low refractive index layer), the strength and It is preferable to have antifouling properties, and from these viewpoints, a resin containing a perfluoro group or a polydimethylsiloxane moiety may be included.

  The coating material for forming the low refractive index layer may be prepared by combining a binder resin forming material, a low refractive index fine particle, a photoinitiator, a solvent, and the like as described below, or these are already mixed. It is also possible to use an ink prepared and inked. In order to adjust the low refractive paint using the following components, the dispersion treatment may be performed according to a general method for adjusting the coating liquid.

  As a material for forming the low refractive index layer, a publicly known material for forming a low refractive index layer that is generally used may be used. For example, a coating solution containing low refractive index inorganic fine particles such as silica or magnesium fluoride having voids and a binder resin forming material, or a coating solution containing a fluorine-based resin or the like can be used.

  As the binder resin forming material for forming the low refractive index layer, it is possible to use a monomer having a vinyl group, a (meth) acryloyl group, an epoxy group, an oxetanyl group, a prepolymer thereof, a polymer ionizing radiation curable resin. it can. Here, “(meth) acryloyl group” means “acryloyl group” and / or “methacryloyl group”. Moreover, when using a thermosetting binder, you may use an inorganic binder. Examples of the inorganic binder include silica sol. Examples of the silica sol include a silica sol using a silicon alkoxide and an acid catalyst or an alkali catalyst as starting materials. As the silicon alkoxide, for example, tetramethoxysilane, tetraethoxysilane, or the like is used.

  When the ionizing radiation curable resin contained in the low refractive index layer is cured, when a UV irradiation is performed, a photopolymerization initiator is added to the coating solution for the low refractive index layer. Photopolymerization initiators include acetophenones, benzophenones, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, thiuram compounds, fluoroamine compounds Etc. are used. These can be used alone or in combination of two or more. Usually, the amount of the photopolymerization initiator used is preferably about 1 to 15% by mass with respect to the mass of the ionizing radiation curable resin to be used.

  As other components of the composition of the low refractive index layer, additives such as a polymerization inhibitor, an antioxidant, a dispersant, a surfactant, a light stabilizer and a leveling agent may be added. Further, an arbitrary amount of solvent can be added as long as the film is dried after film formation by a wet coating method.

  The method for forming the low refractive index layer on the hard coat layer is not particularly limited, and can be formed by applying a coating solution containing the above material on the hard coat layer in the same manner as the hard coat layer described above.

  Moreover, in the antireflection film of the present invention, a near-infrared absorbing layer can be further disposed on the other main surface side of the transparent polyester base material. As a result, if the antireflection film of this embodiment is disposed on the surface of the PDP, unnecessary near infrared rays emitted when plasma discharge is generated are blocked, which may adversely affect devices using peripheral electronic components. In particular, problems such as malfunctions of remote controls such as TVs and air conditioners can be solved.

  The material of the near-infrared absorbing layer is not particularly limited as long as it is a light-transmitting material that absorbs near-infrared rays. Usually, a resin in which a compound that absorbs near-infrared rays is dispersed is used.

  The compound that absorbs near infrared rays is preferably a compound having a maximum absorption wavelength in a wavelength region of 850 to 1100 nm. When the near-infrared absorbing layer contains the above compound, it is possible to reduce the near-infrared transmittance in the wavelength region of 850 to 1100 nm without greatly reducing the visible-light transmittance in the wavelength range of 400 to 850 nm. Thereby, the antireflection film of this embodiment can be used suitably also as near-infrared absorption filters, such as PDP.

  Examples of the compound having the maximum absorption wavelength in the wavelength region of 850 to 1100 nm include, for example, aminium-based, azo-based, azine-based, anthraquinone-based, indigoid-based, oxazine-based, quinophthalonine-based, squalium-based, stilbene-based, and triphenylmethane-based compounds. Organic pigments such as naphthoquinone, diimonium, phthalocyanine, cyanine, and polymethine can be used.

  As the resin for dispersing the near-infrared absorbing compound, polyester resin, acrylic resin, polyurethane resin, polyvinyl chloride resin, epoxy resin, polyvinyl acetate resin, polystyrene resin, cellulose resin, polybutyral resin, or the like may be used. It can also be used as a polymer blend by combining two or more of these resins.

  There is no restriction | limiting in particular about the method of forming a near-infrared absorption layer on a polyester base material, It can form by apply | coating the coating liquid containing the said material to a base material similarly to the case of the above-mentioned hard-coat layer. The thickness of the near infrared absorbing layer is preferably 1 to 10 μm, and more preferably 2 to 7 μm. If the thickness is less than 1 μm, the absorption of near infrared rays tends to be difficult, and if it exceeds 10 μm, cracking or curling (warping of the film) tends to occur. The above range is preferable.

  A compound that cuts the neon emission line spectrum (orange) of PDP can be appropriately added to the near-infrared absorbing layer. Thereby, red color can be more vividly developed in the PDP. As the compound that cuts off the neon emission line spectrum, an organic dye having a maximum absorption wavelength in the wavelength region of 580 to 620 nm can be used. For example, cyanine-based, azulenium-based, squalium-based, diphenylmethane-based, triphenylmethane-based, oxazine-based, Organic dyes such as azine, thiopylium, viologen, azo, azo metal complex, azaporphyrin, bisazo, anthraquinone, and phthalocyanine can be used.

  What is necessary is just to determine suitably the thickness of the said near-infrared absorption layer, the kind of material, content rate, etc. so that the spectral transmission factor of an antireflection film may be 20% or less in the whole area | region of wavelength 850-1100 nm. It should be noted that a primer layer for easy adhesion may be provided on the main surface of the polyester base on the side where the near-infrared absorbing layer is provided, and usually a primer layer may be provided. preferable. In addition, if necessary, the main surface of the polyester base on the side where the near-infrared absorbing layer is provided may be subjected to easy adhesion surface pretreatment such as corona treatment or plasma treatment.

  Hereinafter, the present invention will be described with reference to the drawings, but the description of matters common to the above-described embodiments may be omitted.

  FIG. 1 is a cross-sectional view showing an example of the antireflection film of the present invention. In FIG. 1, an antireflection film 1 is provided directly on a polyester base material 10 and one main surface 10 a of the polyester base material 10 without an intermediate layer such as a primer layer for easy adhesion. In addition, a low refractive index layer 12 is provided on the hard coat layer 11. The hard coat layer 11 and the low refractive index layer 12 form an antireflection layer.

  FIG. 2 is a cross-sectional view showing another example of the antireflection film of the present invention. The antireflection film 2 shown in FIG. 2 is the same as that shown in FIG. 1 except that a near-infrared absorbing layer 14 is provided on the other main surface 10b of the polyester substrate 10 via a primer layer 13. Since it is the same as the antireflection film, the same parts as those of the antireflection film in FIG.

  In the present invention, the hard coat layer needs to be provided directly on the polyester base material without using a primer layer for easy adhesion. On the main surface side opposite to the side where the layer is provided, for example, as shown in FIG. 2, a primer layer for easy adhesion may be provided as required. In the present invention, “the hard coat layer is directly provided on the polyester substrate” means that not only the primer layer for easy adhesion is provided but also the other layers are the hard coat layer and the polyester group. It means that it is not provided between the materials.

  However, except that the hard coat layer is provided directly on the polyester base material, other appropriate functional layers such as an antistatic layer, a high refractive index layer, and an antifouling layer are required. Accordingly, providing between the hard coat layer and the low refractive index layer or providing on the low refractive index layer is optional as long as the object of the present invention is not impaired. On the main surface side opposite to the side on which the hard coat layer of the polyester substrate is provided, a near-infrared absorbing layer or other adhesive layer or electromagnetic wave shielding layer as shown in FIG. 2 unless the object of the present invention is impaired. An appropriate functional layer such as can be provided as required.

  The antireflection film of the present invention as described above is used by being provided on the front surface of, for example, a plasma display panel (PDP) or a liquid crystal display that is used as a display panel of various electronic devices including large televisions. In that case, it is used such that the main surface opposite to the antireflection layer of the antireflection film is the display side.

  The display front plate of the present invention comprises a substrate on which the antireflection film of the present invention as described above is disposed.

  The substrate of the display front plate of the present invention is not particularly limited as long as it is optically transparent and has sufficient strength to protect the display. A plastic substrate is used.

  The thickness of the substrate also varies depending on the type of display and the material of the substrate, and is not particularly limited, but is usually 0.2 to 20 mm, preferably 0.2 to 15 mm.

  Adhesion of the antireflection film of the present invention to the substrate may be suitably performed on the substrate with an adhesive or a pressure-sensitive adhesive. Also in this case, as described above, the antireflection film of the present invention is bonded to the substrate so that the main surface opposite to the antireflection layer is the substrate side of the display front plate.

  The display front plate of the present invention is applied to the front side of the display surface of a display such as a liquid crystal display or a plasma display panel (PDP), and has an antireflection function or an antireflection function depending on the type of constituent layers of the antireflection film used. It is possible to provide a display front plate capable of exhibiting a function and a function as a filter for shielding near infrared rays.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to a following example. In the examples and comparative examples, “parts” means parts by weight. The volume content was obtained by calculation from the weight ratio of the metal oxide and the resin solid content and the specific gravity literature value of each material.

Example 1
An antireflection film for evaluation having the same structure as that of the antireflection film shown in FIG. 2 was prepared as follows.

As a polyester base material, an ultraviolet-cutting polyethylene terephthalate (PET) film having a thickness of 100 μm, on which a silica-containing primer layer made of an acrylic resin is formed on only one surface, to which an ultraviolet absorber is added (total light transmittance: 92 0.0% refractive index 1.66) was prepared. And antimony-doped tin oxide fine particles (Mitsubishi Materials, average particle size 20 nm) 5.5 parts Zirconium oxide fine particles (first rare element, average particle size 10 nm) 4.5 parts
Disperbyk-180 (Distributor manufactured by Big Chemie) 1.0 parts Acetylacetone 5.0 parts 30 ml of propylene glycol monomethyl ether and 0.3 mm diameter zirconia beads are placed in a container and dispersed in a paint shaker for 3 hours, after which the zirconia beads are removed and ATO A dispersion with a / ZrO ₂ weight ratio of 55:45 was prepared.

To this dispersion, pentaerythritol triacrylate 2 parts dipentaerythritol hexaacrylate 2.7 parts
IRGCURE907 (a photopolymerization initiator manufactured by Ciba Specialty Chemicals) 0.3 parts was added to prepare a hard coat layer-forming paint (hereinafter simply referred to as a hard coat layer paint).

The hard coat layer paint is applied to the surface of the light-transmitting PET film with the primer layer on which the primer layer is not provided, using a micro gravure coater (manufactured by Yasui Seiki Co., Ltd.). And then dried. Subsequently, the coating film was cured by irradiating the coating film with ultraviolet rays at a dose of 500 mJ / cm ² to form a hard coating layer having a thickness of 1.5 μm (ratio of metal oxide in the coating film: 29 vol% Refractive index 1.64).

Thereafter, a hollow silica fine particle-dispersed ionizing radiation curable low refractive index paint (“ELCOM P-5013” manufactured by Catalytic Chemical Co., Ltd.) was applied on the hard coat layer using a microgravure coater and dried. . Thereafter, the coating film was cured by irradiating the coating film with ultraviolet rays at a dose of 800 mJ / cm ² to form a low refractive index layer having a thickness of 107 nm.

<Preparation of near-infrared absorbing layer coating material>
The following materials were mixed and stirred to prepare a near-infrared absorbing layer coating material.
(1) Acrylic resin “Dianar” (Mitsubishi Rayon Co., Ltd.): 100 parts (2) Aromatic dimonium dye “CIR-1085” (Nihon Carlit Co., Ltd.): 6 parts (3) Cyanine moiety / dithiol metal complex moiety included Near-infrared absorbing compound "SD50-E0
4N "(manufactured by Sumitomo Seika Co., Ltd., maximum absorption wavelength: 877 nm): 1 part (4) Near-infrared absorbing compound containing a cyanine moiety / dithiol metal complex moiety" SD50-E0
5N "(manufactured by Sumitomo Seika Co., Ltd., maximum absorption wavelength: 833 nm): 1 part (5) methyl ethyl ketone: 125 parts (6) toluene: 460 parts Next, on the primer layer of the PET base material, the near infrared absorption The layer coating was applied using the microgravure coater, a near infrared absorption layer was formed to a thickness of 4 μm, and an antireflection film for evaluation was prepared.

(Example 2)
Antimony-doped tin oxide fine particles (Mitsubishi Materials, average particle size 20 nm) 6 parts Zirconium oxide fine particles (Daiichi Rare Element, average particle size 10 nm) 4 parts
Disperbyk-180 (Dispersant manufactured by Big Chemie) 1.0 parts Acetylacetone 5.0 parts 30 parts of propylene glycol monomethyl ether and 0.3 mm diameter zirconia beads were placed in a container, dispersed for 3 hours with a paint shaker, and then removed to remove zirconia beads. ATO / ZrO ₂ weight ratio was adjusted using a 60:40 dispersion.

To this dispersion, 1.7 parts of pentaerythritol triacrylate 1.6 parts of dipentaerythritol hexaacrylate
IRGCURE907 (a photopolymerization initiator manufactured by Ciba Specialty Chemicals) 0.3 part was added to prepare a coating for a hard coat layer.
An antireflection film for evaluation was prepared by forming an antireflection layer and a near-infrared absorbing layer in the same manner as in Example 1 except that this hard coat coating was used (ratio of metal oxide in the hard coat layer) 36vol% Hard coat layer refractive index 1.68).

(Example 3)
Antimony-doped tin oxide fine particles (Mitsubishi Materials, average particle size 20 nm) 4.5 parts Zirconium oxide fine particles (Daiichi Rare Element, average particle size 10 nm) 5.5 parts
Disperbyk-180 (Dispersant manufactured by Big Chemie) 1.0 parts Acetylacetone 5.0 parts 30 parts of propylene glycol monomethyl ether and 0.3 mm diameter zirconia beads were placed in a container, dispersed for 3 hours with a paint shaker, and then removed to remove zirconia beads. ATO / ZrO _{2 was} prepared using a dispersion having a weight ratio of 45:55.

To this dispersion, 3 parts pentaerythritol triacrylate 3 parts dipentaerythritol hexaacrylate
IRGCURE907 (Ciba Specialty Chemicals photopolymerization initiator) 0.5 part was added to prepare a hard coat layer coating.
An antireflection film for evaluation was prepared by forming an antireflection layer and a near-infrared absorbing layer in the same manner as in Example 1 except that this hard coat coating was used (ratio of metal oxide in the hard coat layer) 24vol% Hard coat layer refractive index 1.63).

(Example 4)
Antimony-doped tin oxide fine particles (Mitsubishi Materials, average particle size 20 nm) 6 parts Zirconium oxide fine particles (made by 1st rare element, average particle size 10 nm) 4 parts
Disperbyk-180 (Dispersant manufactured by Big Chemie) 1.0 parts Acetylacetone 5.0 parts 30 parts of propylene glycol monomethyl ether and 0.3 mm diameter zirconia beads were placed in a container, dispersed for 3 hours with a paint shaker, and then removed to remove zirconia beads. The ATO / ZrO ₂ weight ratio was adjusted using a 60:40 dispersion.

To this dispersion, 1.9 parts pentaerythritol triacrylate 1.9 parts dipentaerythritol hexaacrylate
IRGCURE907 (a photopolymerization initiator manufactured by Ciba Specialty Chemicals) 0.3 part was added to prepare a coating for a hard coat layer.
An antireflection film for evaluation was prepared by forming an antireflection layer and a near-infrared absorbing layer in the same manner as in Example 1 except that this hard coat coating was used (ratio of metal oxide in the hard coat layer) 31vol% Hard coat layer refractive index 1.66).

(Comparative Example 1)
Antimony-doped tin oxide fine particles (Mitsubishi Materials, average particle size 20 nm) 6.5 parts Zirconium oxide fine particles (1st rare element, average particle size 10 nm) 3.5 parts
Disperbyk-180 (Dispersant manufactured by Big Chemie) 1.0 parts Acetylacetone 5.0 parts 30 parts of propylene glycol monomethyl ether and 0.3 mm diameter zirconia beads were placed in a container, dispersed for 3 hours with a paint shaker, and then removed to remove zirconia beads. ATO / ZrO _{2 was} prepared using a dispersion having a weight ratio of 65:35.

To this dispersion, 5 parts pentaerythritol triacrylate 5 parts dipentaerythritol hexaacrylate
IRGCURE907 (a photopolymerization initiator manufactured by Ciba Specialty Chemicals) 0.7 parts of propylene glycol monomethyl ether was added to prepare a hard coat layer coating material.
An antireflection film for evaluation was produced by forming an antireflection layer and a near-infrared absorbing layer in the same manner as in Example 1 except that this hard coat layer coating was used (the metal oxide in the hard coat layer was formed). Ratio 16vol% Hard coat layer refractive index 1.59).

(Comparative Example 2)
As a base material, an ultraviolet-cutting polyethylene terephthalate (PET) film (total light transmittance: 92.1%) having a thickness of 100 μm and having a primer layer (refractive index of 1.58) made of a silica-containing polyester resin on both sides is formed. An antireflection film for evaluation was produced by forming an antireflection layer and a near-infrared absorbing layer in the same manner as in Example 1 except that the antireflection film was used.

(Comparative Example 3)
Antimony-doped tin oxide fine particles (Mitsubishi Materials, average particle size 20 nm) 10 parts
Disperbyk-180 (Dispersant manufactured by Big Chemie) 1.0 part acetylacetone 5.0 parts 30 parts of propylene glycol monomethyl ether and 0.3 mm diameter zirconia beads were placed in a container, dispersed for 3 hours with a paint shaker, and then removed to remove zirconia beads. Adjusted using ATO dispersion.

To this dispersion, 1.1 parts pentaerythritol triacrylate 1.1 parts dipentaerythritol hexaacrylate
IRGCURE907 (a photopolymerization initiator manufactured by Ciba Specialty Chemicals) 0.15 part was added to prepare a coating for a hard coat layer. An antireflection film for evaluation was prepared by forming an antireflection layer and a near-infrared absorbing layer in the same manner as in Example 1 except that this hard coat coating was used (ratio of metal oxide in the hard coat layer) 45vol% Hard coat layer refractive index 1.69).

  The characteristics of the antireflection films of Examples 1 to 4 and Comparative Examples 1 to 3 were evaluated as follows.

<Refractive index>
The refractive index of the hard coat layer of the antireflection film for each evaluation was measured with a refractive index measuring apparatus “FilmTek 3000” (manufactured by SCI).

<Scratch hardness (pencil method)>
The scratch hardness (pencil method) of the hard coat layer of each antireflection film for evaluation was measured based on JIS K5600-5-4: 1999.

<Adhesiveness>
In accordance with JIS K5600-5-6: 1999, an adhesion (cross-cut method) test was performed to evaluate the adhesion between the PET base material and the antireflection layer (however, a quadrangular pattern generated by cross-cut) Was cut to make 100). The results are shown in Table 1. Specifically, in Table 1, the case where there was no part peeled from 100 grids was indicated by ○, and the others were indicated by ×.

<Reflectivity / Visibility reflectivity>
Using a spectrophotometer "Ubest V-570" (manufactured by JASCO Corporation), the luminous reflectance of the antireflection film was shaved with a sandpaper on the side opposite to the antireflection layer, and then a black oil felt pen Then, the measurement was performed using a spectrophotometer “Ubest V-570 type” (manufactured by JASCO Corporation).

<Near-infrared transmittance>
Using the spectrophotometer, the maximum value of the transmittance in the near infrared wavelength region of 850 to 1100 nm was measured for the antireflection film after providing the near infrared absorption layer, with the near infrared absorption layer side being the incident light side. . As a result, the near-infrared transmittances of the antireflection films for evaluation in Examples 1 to 4 and Comparative Examples 1 to 3 were all 12% or less.

<Haze>
It measured using the Nippon Denshoku Industries Co., Ltd. haze meter.

<Surface resistance value>
Using the surface high resistivity meter “HIRESTA HT-20” (manufactured by Mitsubishi Yuka Kabushiki Kaisha), using the antireflection film for each evaluation after providing the near-infrared absorbing layer, It was measured.

  Table 1 shows the measurement results excluding the near-infrared transmittance.

  As is clear from Table 1, the antireflection films of Examples 1 to 4 are harder and have better adhesion than the antireflection films of Comparative Examples 1 to 3 that do not have the constituent features of claim 1. It can be seen that the maximum difference in reflectance amplitude between 380 nm and 780 nm is small.

  The present invention can be implemented in other forms than the above without departing from the spirit of the present invention. The embodiments disclosed in the present application are examples, and the present invention is not limited thereto. The scope of the present invention is construed in preference to the description of the appended claims rather than the description of the above specification, and all modifications within the scope equivalent to the claims are included in the scope of the claims. It is what

  As described above, according to the present invention, the present invention can provide an antireflection film including an antireflection layer having few interference spots, excellent antireflection performance, and higher scratch resistance. By using the antireflection film of the present invention or the display front plate using the antireflection film, a front filter suitable for various displays, particularly PDPs, can be provided.

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antireflection film 10 Polyester base material 11 Hard-coat layer 12 Low refractive index layer 13 Primer layer 14 Near-infrared absorption layer

Claims (6)

An antireflection film comprising a polyester substrate and an antireflection layer disposed on one main surface side of the polyester substrate by a wet coating method,
The antireflection layer includes a hard coat layer and a low refractive index layer disposed above the hard coat layer from the polyester substrate side,
The hard coat layer is provided directly on the polyester substrate,
The hard coat layer contains a metal oxide, and the ratio of the metal oxide is 20% by volume to 42% by volume.   The antireflection film according to claim 1, wherein the main surface of the polyester base on the side where the antireflection layer is disposed is a polyester base that has not been subjected to an easy adhesion surface pretreatment. The antireflection film according to claim 1 or 2, wherein the antireflection layer is not peeled off from the polyester base material in a substrate peel test performed based on JIS K5600-5-6.   The antireflection film according to any one of claims 1 to 3, wherein a maximum value of a difference in reflectance amplitude at 380 nm to 780 nm of the antireflection film is 1.0% or less.   5. The antireflection film according to claim 1, wherein a near-infrared absorbing layer is disposed on the other main surface side of the polyester base material.   A front plate for a display, wherein the antireflection film according to any one of claims 1 to 5 is disposed on a substrate.

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