JP2006189752A - Antireflection film having antistatic filler, and filter for display having the antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film suitable for a filter for a display, etc., and superior in light transmittance, color reproducibility, etc. <P>SOLUTION: The antireflection film is obtained, by disposing on a transparent base material, one or more layers that are different from the transparent base material in the refractive index, wherein the transparent base material has a refractive index of ≤1.54 and the layers include resin and an antistatic filler, comprising conductive fine particles having proton conductivity dispersed in the resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an antireflection film useful for a front filter of a plasma display panel (PDP), a liquid crystal display (LCD) and other displays, an antistatic filler useful for the antireflection film, and a display having the antireflection film. The present invention relates to a front filter.

  In general, a front filter is always used for PDP and LCD. These front filters can cut near-infrared rays, improve color reproducibility (emission color purity improvement), electromagnetic wave shield, improve bright contrast (antireflection), protect the light-emitting panel, block heat from the light-emitting panel, etc. Plays the role of

  It is necessary to reduce the near infrared rays emitted from the light emitting panel of the PDP in order to avoid malfunctioning the remote control used for home television and video. In addition, it is necessary to reduce the electromagnetic waves emitted by the light emitting panel of the PDP in order to avoid adverse effects on the human body and precision equipment. Furthermore, in order to make the light emitted from the light emitting panel of the PDP feel a natural color for human vision, a device for improving color reproducibility (light emission color purity improvement) is also required by correction with a filter. Further, it is desirable that the display on the display is visually recognized with sufficient contrast without being hindered by reflection of light from the outside even in a bright place such as a bright room. Furthermore, even when the display product is directly touched by hand, the heat generated by the light emitting panel of the PDP is required to be cut off in order to avoid a situation where the user is surprised by the high temperature. In order to prevent the product from being easily damaged, it is desirable that the light-emitting panel be protected so that the fragments do not scatter even if it is damaged.

  The structure of a typical front filter for PDP along the above purpose is illustrated in FIG. An antireflection layer 21, an electromagnetic wave shielding layer 22, a color tone correction filter layer 24, and a near infrared cut layer 25 are laminated on a transparent substrate 23, and this is installed as a filter on the front surface of the light emitting panel 20. The order of lamination is changed according to the purpose.

  In this front filter for PDP, the antireflection layer is generally produced as an antireflection film having both light transmittance and antireflection properties, and is used as one layer of the filter. The same applies to the LCD front filter.

  Such an antireflection layer is manufactured as a multilayer laminate (antireflection film) including a plurality of thin layers having different refractive indexes designed to reduce reflected light as much as possible. Although it is possible to produce this multilayer laminate by a dry process such as a vacuum deposition method or a sputtering method, generally this dry process requires a vacuum manufacturing facility, and when mass production is required, Manufacturing costs are inevitably increased. For this reason, the formation of a multilayer laminate of antireflection films by a wet coating method such as solution coating is widely used.

  The general structure of such an antireflection film by wet coating is illustrated in FIG. This antireflection film is obtained by laminating a transparent base material 33 with a high refractive index layer 32 having hard coat properties and a low refractive index layer 31 having a lower refractive index than the high refractive index layer 32. Antireflective properties are imparted by the refractive index layer 31, and it has a role of preventing the visibility from being reduced due to reflection of external light incident from the low refractive index layer 31 side.

  In actual use, dust or the like often adheres to the front surface of the display filter due to charging. The attached dust greatly impairs the optical performance of the display filter. In order to reduce the adhesion of dust and the like, the antireflection film is usually manufactured with further antistatic performance. For example, an antireflection film provided on the surface of the filter is provided with a layer having antistatic properties.

  In order to obtain a layer having antistatic properties, electrical conductivity is usually imparted to the layer. As such a layer, for example, a thin film layer in which conductive metal oxide fine particles such as tin oxide are finely dispersed in a synthetic resin or a surfactant-containing thin film layer is used. Since the antistatic layer made of a surfactant is easily affected by the antistatic performance due to environmental conditions such as humidity, an antistatic layer using conductive metal oxide fine particles which are hardly affected by the environmental conditions is generally preferable.

  In such a case, conductive fine particles such as ITO (indium oxide / tin oxide), ATO (antimony oxide / tin oxide), tin oxide, etc. are used as antistatic fillers with conductive metal oxide fine particles. .

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-75603) discloses that in an example, a medium refractive index layer, a high refractive index layer, and a low refractive index layer are sequentially laminated on a triacetyl cellulose (TAC) film. An antireflection film having an antistatic function by incorporating conductive metal oxide fine particles such as tin oxide and ATO into the refractive index layer is disclosed. This TAC film is excellent in properties such as adhesiveness and has a relatively low refractive index (refractive index of about 1.49 to 1.50). It is widely used for reasons such as increasing the degree of freedom in selecting the material.

JP 2003-75603 A

  However, the above-mentioned conductive metal oxide fine particles such as ITO (indium oxide / tin oxide), ATO (antimony oxide / tin oxide), tin oxide, etc. are used as an antistatic filler, so that it has an antistatic function. In the case where the layer having the antistatic layer is provided, there is a disadvantage that the color deviation and the decrease in light transmittance become prominent according to the amount of the antistatic filler used and the increase in the thickness of the antistatic layer to be installed. . In addition, when these conductive metal oxide fine particles that are usually used are used as antistatic fillers, the refractive index of the layer tends to be relatively large, which causes restrictions on optical design. There was also an inconvenience.

  Furthermore, a so-called hard coat layer usually requires a thickness of about 1 μm to several μm, for example, about 5 μm, in order to achieve the hardness required for its hard coat properties. And when introduce | transducing the filler of electroconductive metal oxide fine particles, such as ITO and ATO, it is preferable also on manufacture operation to introduce | transduce into a hard-coat layer with comparatively thickness. However, when a conductive metal oxide fine particle filler such as ITO or ATO is used as a layer having a thickness of about 5 μm, the transmittance of the antireflection film is lowered and the color is unbalanced. The problem that the reproducibility deteriorated appeared remarkably.

  The occurrence of such a color deviation or a decrease in light transmittance is considered to be because the filler of conductive metal oxide fine particles such as ITO and ATO has light absorption characteristics from the infrared region to the visible light region. Therefore, as long as a conductive metal oxide fine particle filler such as ITO or ATO is used, the filler must be introduced into a layer having a thickness smaller than about 1 μm. For this reason, it has been particularly difficult to add a function as an antistatic layer to a high refractive index layer (hard coat layer) having hard coat properties.

  Accordingly, an object of the present invention is an antireflection film useful for a front filter or the like of a plasma display panel (PDP) or other display, and is provided with antistatic properties without deteriorating light transmittance and color reproducibility. Another object is to provide an antireflection film.

  Furthermore, the objective of this invention is also providing the filter for a display which has said antireflection film.

The inventors of the present invention provide an antireflection film in which at least one layer having a different refractive index is provided on a transparent substrate, and the refractive index of the transparent substrate is 1.54. And
The layer is achieved by an antireflection film which is a layer containing a resin and an antistatic filler comprising conductive fine particles having proton conductivity dispersed in the resin;
The inventors have found that antimony oxide (Sb ₂ O ₅ ) fine particles having a pyrochlore structure are particularly suitable as antistatic fillers composed of conductive fine particles having proton conductivity.

  That is, when the antistatic filler is dispersed in a layer and used, an antistatic layer having excellent light transmittance and no color bias can be obtained.

  In addition, when the antistatic filler is used for the layer, there is an advantage that the refractive index of the layer is not increased excessively as compared with the filler of conductive metal oxide fine particles such as ITO and ATO. That is, if the antistatic filler is used, an increase in the refractive index due to the use of the filler itself can be reduced, and the degree of freedom in designing the arrangement of the refractive index of the laminated structure can be increased. In particular, it is suitable when a TAC (triacetyl cellulose) film (refractive index of about 1.49 to 1.50) having a relatively low refractive index is used as the transparent substrate.

  Further, on the transparent substrate, a hard coat layer and a low refractive index layer having a refractive index smaller than that of the hard coat layer are sequentially laminated, and the hard coat layer is dispersed in the resin and the resin. A reflective film which is a layer containing an antistatic filler made of conductive fine particles having conductivity is preferable.

  According to the present invention, even when a layer having a thickness of several μm or more, which is required as a hard coat layer, is formed, the antistatic layer has sufficient light transmittance and excellent properties that do not cause color deviation. Show. In addition, when it becomes possible to disperse the antistatic filler in the hard coat layer having a thickness of about several μm, the antistatic filler must be uniformly dispersed in the layer of about several tens of nm. In comparison, the workability is greatly improved. The characteristics of the antireflection film of the present invention are excellent by these.

  Although the details of the reason why the above antistatic filler exhibits such excellent properties are not clear, the present inventors consider that the light absorption property by proton conductivity is important. This proton conductivity means the conductivity carried by proton transfer.

  The fillers of conductive metal oxide fine particles such as ITO and ATO, which have been used conventionally for antistatic purposes, correspond to so-called electron conductive fillers that are conductive by electron transfer. Although this has a relatively high conductivity, it is considered that this has a light absorption characteristic from the infrared region to the visible light region. In the present invention, by selecting proton-conductive conductive fine particles as the antistatic filler, the light absorption can be extremely reduced in the visible light region, and the filler exhibits the above excellent characteristics. It is thought that.

Pyrochlore structure refers to a structure similar to pyrochlore. Pyrochlore has the chemical formula of (Na, Ca, U) ₂ (Nb, Ta, Ti) ₂ O ₆ (OH, F), the point group is 4 / m32 / m, the space group is Fd3m, cubic system It is a mineral belonging to. The pyrochlore group (Hylosite group) has a general chemical composition formula of A _{1 to 2} B ₂ O ₆ (O, OH, F) · H ₂ O (where A = Ba, Bi, Ca, Ce, Cs, K, Na, Pb, Sb ⁺³ , Sn, Sr, Th, U, Y, Zr; B = complex cubic oxide having Fe, Nb, Sn, Ta, Ti). In the general formula of A ₂ B ₂ X ₆ X ′, antimony oxide (Sb ₂ O ₅ ) used in the present invention has H as A, Sb as B, and O and OH as X and X ′. Protons derived from water contained in the crystal structure are considered to contribute to proton conductivity.

  Therefore, an antistatic layer having high transparency and little color deviation can be obtained by using the conductive fine particles in the layer as an antistatic filler. Further, even when used for a relatively thick layer thickness required as a hard coat layer, it has an advantage that it has sufficient light transmittance and does not cause color deviation.

  The average particle diameter of the conductive fine particles is generally in the range of 5 to 300 nm. The layer containing the antistatic filler contains the antistatic filler in a proportion of generally 4 to 35% by mass with respect to the total mass of the layer containing the antistatic filler. The thickness of the layer containing the antistatic filler is generally 1 to 10 μm as a range that can be formed while taking advantage of the properties of the antistatic filler.

  Although various materials can be used as the transparent substrate, organic resin polymers are preferable, and triacetyl cellulose (TAC) is particularly preferable from the viewpoint of refractive index and the like. By using a low refractive index material such as TAC for the transparent base material, a certain interference fringe suppressing effect can be realized without newly adding an intermediate layer (intermediate refractive index layer) or the like.

  The low refractive index layer preferably contains a resin in which hollow silica fine particles are dispersed. By using hollow silica fine particles (porous silica), it is possible to achieve both low refractive index and surface hardness. The resin is preferably an ultraviolet curable resin from the viewpoint of hardness.

  Furthermore, in the antireflection film of the present invention, the refractive index of the transparent substrate is in the range of 1.44 to 1.54, and the refractive index of the hard coat layer is in the range of 1.44 to 1.57. Preferably. A transparent resin having a relatively low refractive index is suitable as a transparent substrate when such a refractive index configuration is adopted, and if this is used, a suitable implementation excellent in reducing interference fringes is possible. . As a transparent resin having a relatively low refractive index, a TAC (triacetyl cellulose) film (refractive index of about 1.49 to 1.50) is particularly suitable from the viewpoint of adhesiveness.

  Moreover, if the said antireflection film is used, the filter for a display excellent in antireflection performance, light transmittance, color reproducibility, etc. can be obtained. That is, the present invention is also in a display filter having the antireflection display.

  Furthermore, by installing the antireflection film as the outermost layer, a display filter that exhibits the antireflection performance of the antireflection film and appropriate hard coat properties can be obtained. That is, the present invention also includes a display filter in which the antireflection film is provided as an outermost layer.

  The antireflection film of the present invention prevents dust from adhering by preventing charging, and maintains excellent light transmission and color reproducibility while preventing deterioration of optical performance due to adhesion of dust and the like. If this anti-reflection film is used as a front filter for a display such as a PDP or a liquid crystal display, the image on the display is clearly displayed while preventing the visibility from being reduced due to reflection of light from the outside of the display. Moreover, it can be enjoyed with good color reproduction, and further, it is possible to prevent the screen from being blocked or the image from becoming unclear due to dust adhering to the front surface of the display due to charging.

  Moreover, the antireflection film of the present invention has an advantage that workability in the production process is also improved. And if this anti-reflection film is used as a front filter for a display such as a PDP or a liquid crystal display, in addition to the above-mentioned advantages, the front of the display is not easily damaged, so there is little loss of visibility due to scratches, and it can be handled safely A front filter for a display can be provided.

  Furthermore, according to this invention, the antireflection film which reduced the interference fringe called what is called an oil stain can be obtained. Further, according to the present invention, there can be obtained an antireflection film in which interference fringes are sufficiently reduced in various indoor illuminations that are actually used with almost no restrictions on the wavelength of light.

  A display filter using this antireflection film as an antireflection layer enables natural color images to be viewed in a room illuminated by a light source having various wavelength characteristics. It is particularly suitable for use in a PDP display characterized by a natural color tone. However, the application of the antireflection film of the present invention is not limited to a display filter, and can be suitably used for various transparent windows used indoors, display windows for instruments and devices, and the like.

  Furthermore, the antireflection film of the present invention is not limited to indoor use, but has interference fringe reduction characteristics suitable for natural light outdoors and various artificial light sources, and for displays used in such scenes. It can also be suitably used in filters, various transparent windows, and display windows for instruments and devices.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of the antireflection film of the present invention. In FIG. 1, the hard coat layer 12 is provided with antistatic properties by including a resin in which an antistatic filler is dispersed while having a certain hardness and a required thickness on the transparent base layer 14. 1 shows an antireflection film in which a low refractive index layer 11 having a refractive index lower than that of a hard coat layer is sequentially laminated. Outside light such as room illumination light is installed so as to enter from the low refractive index layer 11 side. When manufacturing as a filter for a display, various layers are further laminated on the back side of the transparent base material layer 14, for example, a near infrared cut layer, a color tone correction filter layer, an electromagnetic wave shielding layer, or a self-supporting transparent base material. If necessary, it is further laminated via the adhesive layer.

The antireflection film having the configuration shown in FIG. 1 realizes antireflection performance with a small number of layers because the hard coat layer serves as a so-called high refractive index layer. Furthermore, by using a low refractive index material such as TAC as the transparent substrate layer, a certain interference fringe reduction performance can be realized. The hard coat layer contains a resin in which an antistatic filler made of conductive fine particles having proton conductivity, particularly, antimony oxide (Sb ₂ O ₅ ) fine particles having a pyrochlore structure is dispersed. As a result, an antistatic layer having high transparency and little color deviation is obtained as an integral layer with the hard coat layer. For the purpose of preventing the adhesion of dust or the like by preventing charging, it is more preferable to include it in the outer layer. In addition, an intermediate layer (intermediate refractive index layer) is provided between the high refractive index hard coat layer and the transparent base material layer to improve adhesion and further reduce interference fringes. It is advantageous from the viewpoint of cost reduction to omit the intermediate layer. That is, there is an advantage of this embodiment in that a certain interference fringe reduction effect is obtained by using TAC (triacetyl cellulose) while omitting the intermediate layer to reduce the cost. However, in an embodiment in which an intermediate layer is provided as desired, the thickness d (nm) of the intermediate layer can generally be in the range of 5 to 40 nm, preferably in the range of 5 to 30 nm, and particularly in the range of 10 to 30 nm. The range of is preferable.

  Furthermore, in the antireflection film of the present invention, the refractive index of the transparent substrate is in the range of 1.44 to 1.54, and the refractive index of the hard coat layer is in the range of 1.44 to 1.57. Preferably. In this invention, the refractive index of a hard-coat layer can be made low by using the said antistatic filler. A transparent resin having a relatively low refractive index is suitable as a transparent substrate when such a refractive index configuration is adopted, and if this is used, a suitable implementation excellent in reducing interference fringes is possible. . As a transparent resin having a relatively low refractive index, a TAC (triacetylcellulose) film (refractive index of about 1.49 to 1.50) is particularly suitable from the viewpoint of reducing interference fringes and adhesion to other layers. is there.

  Further, as the above refractive index range, the refractive index of the transparent base material can be in the range of 1.44 to 1.54, preferably in the range of 1.46 to 1.52, and particularly preferably. Is in the range of 1.48 to 1.51, and the refractive index of the hard coat layer can be in the range of 1.44 to 1.57, preferably in the range of 1.46 to 1.56. Yes, particularly preferably in the range of 1.48 to 1.55.

  The average particle diameter of the conductive fine particles is generally in the range of 5 to 300 nm, preferably in the range of 10 to 200 nm, and particularly preferably in the range of 15 to 150 nm. From the viewpoint of transparency, the smaller the particle diameter, the better, but from the viewpoint of the antistatic effect, the larger the particle diameter is preferable.

  In addition, the hard coat layer generally contains the antistatic filler in a ratio of 4 to 35% by mass, preferably in the range of 5 to 30% by mass, particularly 6 to 25% by mass with respect to the total mass of the hard coat layer. It is preferable to contain in the ratio of the range of%. From the viewpoint of the antistatic effect, the larger the content ratio of the antistatic filler, the better. However, from the viewpoint of imparting flexibility required for the hard coat layer, the smaller the content ratio, the more preferable.

  The thickness of the hard coat layer is generally from 1 to 10 μm, preferably from 2 to 8 μm, particularly preferably from 3 to 6 μm, as a range that can be formed while taking advantage of the properties of the antistatic filler.

  As the resin in which the conductive fine particles are dispersed, various transparent resins that can be used for the hard coat layer can be used, but a layer made of a cured film of a thermosetting resin or an ultraviolet curable resin is preferable. By using the curable resin, the hard coat layer can be provided on the transparent substrate layer very easily.

  As the thermosetting resin, a thermosetting silicone composition (for example, methyltrimethoxysilane that forms an organic polysiloxane) is preferable, and three-dimensional crosslinking is performed in the dehydration condensation of silanol groups to obtain a high hardness coating. Generally, it can be cured by heating at 80 to 220 ° C. for 10 minutes to 1 hour.

  Further, as the curable resin, a resin or oligomer having an ethylenic double bond (preferably an acryloyl group or a methacryloyl group) can be used, and this can be generally made into a hard coat layer by photocuring.

  Alternatively, the hard coat layer is also preferably a layer made of a cured film of a curable resin containing silica fine particles. In particular, the hard coat layer can be provided on the transparent substrate layer very easily by using an ultraviolet curable resin.

  The primary particle size of the silica fine particles is preferably in the range of 1 to 200 nm.

  As the ultraviolet curable resin, a known ultraviolet curable resin (including a polymerizable oligomer, a polyfunctional monomer, a monofunctional monomer, a photopolymerization initiator, an additive, and the like) can be used.

  Examples of such ultraviolet curable resins include urethane oligomers having a plurality of ethylenic double bonds (preferably acryloyl groups or methacryloyl groups), oligomers such as polyester oligomers and epoxy oligomers, pentaerythritol tetraacrylate (PETA), and pentaerythritol. It is preferably composed mainly of a polymerizable oligomer such as tetramethacrylate and dipentaerythritol hexaacrylate (DPEHA) and / or a polyfunctional monomer. The functional polymerization monomer used in the production of the modified silica fine particles can also be used as appropriate.

  The ultraviolet curable resin is generally composed of an oligomer, if necessary, a reactive diluent (polyfunctional monomer, monofunctional monomer), and a photopolymerization initiator as described above. Examples of photopolymerization initiators include benzoin, benzophenone, benzoyl methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, dibenzyl, 5-nitroacenaphthene, hexachlorocyclopentadiene, p-nitrodiphenyl, p-nitroaniline. 2,4,6-trinitroaniline, 1,2-benzanthraquinone, 3-methyl-1,3-diaza-1,9-benzanthrone; acetophenone, acetophenone benzyl ketal, anthraquinone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone compounds, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimene Xylbenzophenone, 4,4′-diaminobenzophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, Carbazole, xanthone, 1,1-dimethoxydeoxybenzoin, 3,3′-dimethyl-4-methoxybenzophenone, thioxanthone compound, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 1- (4-dodecylphenyl)- 2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, triphenylamine, 2,4,6-trimethylbenzoyl Diphenylphosphine oxide, bis- (2,6-dimethyl) Toxibenzoyl) -2,4,4-trimethylpentylphosphine oxide, bisacylphosphine oxide, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, Fluorenone, fluorene, benzaldehyde, Michler's ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 3-methylacetophenone, 3,3 ′, 4,4′-tetra ( t-butylperoxycarbonyl) benzophenone (BTTB) and the like, and combinations of BTTB and dye sensitizers such as xanthene, thioxanthene, coumarin, ketocoumarin and the like. Of these, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis- (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one is preferred.

  These can be used alone or in combination of two or more. Each of the oligomer, reactive diluent and initiator may be used alone or in combination of two or more. As for content of a reactive diluent, 0.1-10 mass parts is common with respect to 100 mass parts of ultraviolet curable resin, and 0.5-5 mass parts is preferable. The content of the photopolymerization initiator is preferably 5 parts by mass or less with respect to 100 parts by mass of the ultraviolet curable resin.

  The ultraviolet curable resin may further contain a silicone polymer. Generally, it is a graft copolymer having silicone as a side chain, and preferably an acrylic graft copolymer having silicone as a side chain.

  In the present invention, various additives can be added as necessary to the above. Examples of these additives include antioxidants, ultraviolet absorbers, light stabilizers, silane coupling agents, and anti-aging. Agent, thermal polymerization inhibitor, colorant, leveling agent, surfactant, storage stabilizer, plasticizer, lubricant, solvent, inorganic filler, organic filler, filler, wettability improver, coating surface improver, etc. Can be mentioned.

  The hard coat layer is composed mainly of the above components, but is excellent in various functions by further modification of the above oligomer or monomer, or further use of other functional resins and additives. A hard coat layer can be obtained.

  The antireflection film is formed by lamination on a transparent substrate, and various materials can be used as the material of the transparent substrate, such as polyethylene terephthalate (PET), triacetyl cellulose (TAC), Polyethylene naphthalate (PEN), acrylic resin, polycarbonate; polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA), 4-fluoroethylene-6-fluoropropylene copolymer (FEP), fluoroethylene resins such as 2-ethylene-4-fluoroethylene copolymer (ETFE), poly-3-fluoroethylene chloride (PCTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF) Each film can be mentioned. A PET film and a TAC film are particularly preferable from the viewpoint of transparency and flexibility.

  The thickness of the transparent substrate layer is preferably about 6 to 250 μm.

  In a preferred embodiment of the present invention, a certain interference fringe preventing effect can be obtained without using TAC as a material for the transparent base material layer and providing an intermediate layer (intermediate refractive index layer). However, in order to improve adhesiveness and interference fringe prevention effect, an intermediate layer can be laminated on the transparent substrate layer as desired.

  The material of such an intermediate layer is not particularly limited as long as it has good light transmittance, can achieve a desired refractive index for preventing interference fringes, and can be bonded with a predetermined thickness. It is usable without. Suitable examples include acrylic resins (including sulfur-modified acrylic resins), EVA (ethylene vinyl acetate copolymer), polyvinyl acetal resins (for example, polyvinyl formal, polyvinyl butyral (PVB resin), and modified PVB). And vinyl chloride resin. Particularly preferred are acrylic resins (especially sulfur-modified acrylic resins) and EVA.

  As said acrylic resin, the copolymer of (meth) acrylic acid ester, such as methyl methacrylate, butyl methacrylate, butyl acrylate, 2-hydroxyethyl acrylate, and comonomers, such as acrylic acid and methacrylic acid; or , By introducing a functional group such as a carboxyl group, a hydroxyl group, a methylol group, or a glycidyl group into the side chain of these copolymers, an aliphatic isocyanate such as tetramethylene diisocyanate or trimethylhexamethylene diisocyanate, or TDI (tolylene diisocyanate), An acrylic urethane resin obtained by crosslinking with an aromatic isocyanate such as MDI (diphenylmethane diisocyanate) or NDI (naphthalene diisocyanate) can be exemplified. A particularly preferable example is a sulfur atom as an acrylic resin monomer. By polymerization reaction using a monomer having a functional group having, or is obtained by reacting a compound having a sulfur atom in the functional group of the acrylic resin polymer, mention may be made of sulfur-modified acrylic resin.

  Moreover, a silane coupling agent can be added to EVA resin for the purpose of improving adhesive force. Known silane coupling agents for this purpose are, for example, γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyl-tris- (β-methoxyethoxy) silane; γ-methacryloxy. Propyltrimethoxysilane; β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane; γ-glycidoxypropyltrimethoxysilane; vinyltriacetoxysilane; γ-mercaptopropyltrimethoxysilane; γ-aminopropyltrimethoxysilane N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane and the like can be mentioned. The compounding amount of these silane coupling agents is generally 5 parts by mass or less, preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the EVA resin.

  Furthermore, a crosslinking aid can be added to the EVA resin in order to improve the gel fraction of the EVA resin and improve the durability. As crosslinking aids used for this purpose, known tri-functional crosslinking aids such as triallyl cyanurate and triallyl isocyanurate as well as monofunctional crosslinking aids such as NK ester (trade name) are known. Etc. can also be mentioned. Generally the compounding quantity of these crosslinking adjuvants is 10 mass parts or less with respect to 100 mass parts of EVA resin, Preferably it is 1-5 mass parts.

  Furthermore, hydroquinone; hydroquinone monomethyl ether; p-benzoquinone; methyl hydroquinone and the like can be added for the purpose of improving the stability of the EVA resin, and the blending amount thereof is generally 5 parts by mass with respect to 100 parts by mass of the EVA resin. It is as follows.

  In addition to the above, a colorant, an ultraviolet absorber, an anti-aging agent, a discoloration preventing agent and the like can be added as necessary. Examples of the colorant include inorganic pigments such as metal oxides and metal powders, and organic pigments such as azo-based, phthalocyanine-based, additive-based, acidic or basic dye-based lakes. Examples of ultraviolet absorbers include 2-hydroxy-4-octoxybenzophenone; benzophenones such as 2-hydroxy-4-methoxy-5-sulfobenzophenone; 2- (2′-hydroxy-5-methylphenyl) benzotriazole Benzotriazoles; phenyl salsylates; hindered amines such as pt-butylphenyl salsylates. Antiaging agents include amines; phenols; bisphenyls; hindered amines, such as di-t-butyl-p-cresol; bis (2,2,6,6-tetramethyl-4-piperazyl). ) Sebacate.

  A low refractive index layer is laminated on the hard coat layer.

  The low refractive index layer can be formed of, for example, a fluorine or non-fluorine low refractive index organic thin film.

  Examples of the non-fluorine organic thin film include acrylic resins, silicon resins, acrylic silicon resins, urethane resins and the like used for hard coats.

  Fluorine organic thin films include FET (fluoroethylene / propylene copolymer), PTFE (polytetrafluoroethylene), ETFE (ethylene / tetrafluoroethylene), PVF (polyvinyl fluoride), PVD (polyvinylidene fluoride), etc. Can be mentioned.

  Further, in order to impart antifouling properties, easy slipping, etc., fluorine-based and silicon-based additives may be added. Among these, a silicon resin or an acrylic resin is preferable because it is inexpensive.

  The low refractive index layer may be a layer made of a cured film of a thermosetting resin or an ultraviolet curable resin used for a hard coat layer, and an ultraviolet curable resin is particularly suitable in terms of hardness and handling. is there.

  Since such an organic thin film is generally a low refractive index thin film, it is suitable in the present invention.

In addition, the antistatic filler composed of the fine particles of antimony oxide (Sb ₂ O ₅ ) having the pyrochlore structure contained in the hard coat layer and dispersed in the resin is commonly used ITO (indium oxide / tin oxide), ATO Compared with antistatic fillers made of conductive metal oxide fine particles such as (antimony oxide / tin oxide) and tin oxide, the refractive index is low. Therefore, the refractive index of the hard coat layer containing the antistatic filler can be made relatively low. However, when the refractive index of the hard coat layer is made low by making use of this, the antireflection film In order to sufficiently exhibit the antireflection effect, it is necessary to further lower the refractive index of the low refractive index layer, and it is preferable to set the refractive index to 1.48 or less, for example.

  In order to improve the antireflection performance as described above, as a method for obtaining a low refractive index layer having a low refractive index, there is a method of reducing the refractive index by filling a filler such as hollow silica fine particles (porous silica). . In particular, since the hollow silica fine particles are inorganic compound fillers, the refractive index reduction due to this is preferable in that a harder low refractive index thin film can be formed as compared with the refractive index reduction due to the organic additive. It is particularly preferable when arranged outside.

  Since the hollow silica fine particles are hollow and contain air inside, the refractive index (about 1.34 to 1.44) is much lower than that of ordinary silica (refractive index: about 1.46). This can be produced by covering the surface of porous silica fine particles with an organic silicon compound or the like and closing the pore entrance. The average particle diameter of the hollow silica fine particles can generally be in the range of 1 nm to 1 μm, preferably 5 to 200 nm, and particularly preferably 10 to 100 nm. From the viewpoint of the size of the contribution to lowering the refractive index, the larger the particle size, the better. However, if the particle diameter exceeds about 1 μm, the transparency is extremely lowered and the contribution of diffuse reflection becomes large, and it looks whitish. . From the viewpoint of transparency, the smaller the particle diameter, the better. However, in addition to the above-mentioned contribution to lowering the refractive index, the hollow silica fine particles tend to agglomerate when the particle diameter is smaller than about 0.5 nm. Dispersion is not easy.

  The thickness of the low refractive index layer is preferably an optical film thickness within a range where the antifouling function can be obtained in order to achieve both the antireflection function and the antifouling function, For example, it is preferable to set it to about ¼λ (= 125 nm) of light having a wavelength of 500 nm.

  By forming such an organic thin film on the hard coat layer as a low refractive index layer as the outermost surface layer of the antireflection film, an antireflection function can be obtained, and further excellent antifouling properties and scratch resistance can be obtained. Can also be obtained.

  The following examples further illustrate the present invention. The present invention is not limited by the following examples.

[Example]
Production of antireflection film and display filter of the present invention On a TAC film (refractive index 1.49, 150 μm thickness) as a transparent substrate, dipentaerythritol hexaacrylate (DPHA) (Nippon Kayaku) as a multifunctional acrylate monomer Co., Ltd., trade name DPHA) 75 parts by mass, 25 parts by mass of Sb ₂ O ₅ having an average particle size of 150 nm, 100 parts by mass of MEK, 100 parts by mass of toluene, a photopolymerization initiator (Ciba Specialty) A coating solution containing 4 parts by mass of Tea Chemicals, trade name Irgacure 184) was prepared and applied. Next, after drying at 80 ° C. for about 1 minute, it was cured by ultraviolet irradiation (light quantity 200 mJ / cm ² ) to form a hard coat layer (refractive index 1.54, thickness 5 μm).

Furthermore, 2 parts by mass of DPHA, 2 parts by mass of porous silica (hollow silica fine particles) (average particle size 100 nm), 1 part by mass of a photopolymerization initiator (trade name Irgacure 184, manufactured by Ciba Specialty Chemicals) as a polymerization initiator, A coating solution containing 95 parts by mass of MEK as a solvent was prepared and applied on the hard coat layer described above. Next, after drying at 80 ° C. for about 1 minute, the film was cured by ultraviolet irradiation (light quantity 200 mJ / cm ² ) to form a low refractive index layer (refractive index 1.44, thickness 90 nm).

  Furthermore, this was bonded together to the glass plate of thickness 2.5mm, and the filter for displays was created.

[Comparative example]
Production of antireflection film and display filter using ATO On the same transparent substrate as in the examples, dipentaerythritol hexaacrylate (DPHA) (trade name DPHA, manufactured by Nippon Kayaku Co., Ltd.) as a multifunctional acrylate monomer 50 parts by mass, 50 parts by mass of ATO (antimony-doped tin) having an average particle size of 150 nm, 100 parts by mass of MEK, 100 parts by mass of toluene, a photopolymerization initiator as a polymerization initiator (trade name Irgacure 184, manufactured by Ciba Specialty Chemicals) 4 A coating solution containing parts by mass was prepared and applied. Next, after drying at 80 ° C. for about 1 minute, the film was cured by ultraviolet irradiation (light quantity 200 mJ / cm ² ) to form a hard coat layer (refractive index 1.60, thickness 5 μm).

  A low refractive index layer (refractive index 1.44, thickness 90 nm) was formed on the hard coat layer in the same manner as in the example.

  Furthermore, this was bonded together to the glass plate of thickness 2.5mm, and the filter for displays was created.

[Measurement of transmittance]
The average transmittance in the vicinity of a wavelength of 400 to 800 nm was measured using a Hitachi visible ultraviolet light spectrometer (U-4000).

[Measurement of surface resistance]
The surface resistance value was measured based on JISK6911 by applying 500 V using a digital ultrahigh resistance meter (R8340A) manufactured by Advantest.

[Evaluation of interference fringe generation]
The display filter of the example and the comparative example is used in a room where a three-wavelength fluorescent lamp (product name: FHF32EX-N, manufactured by Toshiba) is used as a ceiling lamp, so that the antireflection film surface is on the indoor side with a smooth wall surface. Installed. The degree of interference fringes (oil stain) generated by illumination of a three-wavelength fluorescent lamp was visually evaluated. The evaluation was performed in three stages: ○: conspicuous interference fringes are hardly visible Δ: conspicuous interference fringes are slightly visible ×: conspicuous interference fringes are clearly visible The results are shown in the following table.

[Evaluation of color]
The color reproducibility was evaluated by measuring the color of the light transmitted through the display filters of Examples and Comparative Examples. Based on JIS Z8729, the spectral transmittance is measured with a Hitachi spectrophotometer, and a C light source is used to calculate the a * value and b * value (CIE 1976 (L * a * b *) / CIELAB). evaluated.

[result]

In the case of having the same surface resistance, a display filter with an anti-reflection hard coat layer in which Sb ₂ O ₅ having a pyrochlore structure is dispersed as a filler has ATO dispersed in the filler. Compared with a display filter made of an antireflection film having an antistatic hard coat layer, while showing high light transmittance, no conspicuous interference fringes were visually recognized. Further, when Sb ₂ O ₅ having a pyrochlore structure is used, the transmitted light has a smaller absolute value for both the a * value and the b * value than when ATO is used, that is, a color close to neutral. There was excellent color reproducibility.

Moreover, the display filter using an antireflection film having an antistatic hard coat layer in which Sb ₂ O ₅ having a pyrochlore structure is dispersed is also excellent in antireflection properties, is difficult to adhere dust, and the front surface is hardly damaged. It was a thing.

  That is, the display filter using an antireflection film using the antistatic filler of the present invention has an antistatic property imparted to the hard coat layer and has an advantageous structure for manufacturing, while having an antireflection property, light transmittance, and color reproduction. It has excellent properties, interference fringe reduction, dust adhesion prevention, scratch prevention, and the like.

FIG. 1 is a cross-sectional view of an example of the basic structure of the antireflection film of the present invention. FIG. 2 is a cross-sectional view showing the structure of a typical front filter for PDP. FIG. 3 is a cross-sectional view showing an example of a general structure of an antireflection film manufactured by a wet coating method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Low refractive index layer 12 Hard coat layer 14 Transparent base material layer 20 Light emitting panel 21 Antireflection layer 22 Electromagnetic wave shielding layer 23 Transparent substrate 24 Color tone correction filter layer 25 Near-infrared cut layer 31 Low refractive index layer 32 High having a hard coat property Refractive index layer 33 Transparent substrate

Claims (12)

An antireflection film in which a layer having a different refractive index of at least one layer is provided on a transparent substrate,
The refractive index of the transparent substrate is 1.54 or less,
An antireflection film, wherein the layer comprises a resin and an antistatic filler made of conductive fine particles having proton conductivity dispersed in the resin. On the transparent substrate, a hard coat layer and a low refractive index layer having a refractive index smaller than that of the hard coat layer are sequentially laminated,
The antireflection film according to claim 1, wherein the hard coat layer is a layer containing an antistatic filler comprising the resin and conductive fine particles having proton conductivity dispersed in the resin.   The antireflection film according to claim 1, wherein the conductive fine particles are fine particles of antimony oxide having a pyrochlore structure.   The antireflection film according to any one of claims 1 to 3, wherein an average particle diameter of the fine particles is in a range of 5 to 300 nm.   The proportion of the antistatic filler in the range of 4 to 35% by mass with respect to the total mass of the layer including the resin and conductive fine particles having proton conductivity dispersed in the resin. The antireflection film according to claim 1, comprising:   The reflection according to any one of claims 1 to 5, wherein the thickness of the layer containing the resin and the antistatic filler made of conductive fine particles having proton conductivity dispersed in the resin is in the range of 1 to 10 µm. Prevention film.   The antireflection film according to claim 1, wherein the transparent substrate is a TAC film.   The antireflection film according to claim 1, wherein the resin in which the antistatic filler is dispersed is an ultraviolet curable resin.   The antireflection film according to claim 2, wherein the low refractive index layer contains a resin in which hollow silica fine particles are dispersed.   The refractive index of the said transparent base material exists in the range of 1.44-1.54, and the refractive index of the said hard-coat layer exists in the range of 1.44-1.57. Antireflection film.   A display filter comprising the antireflection film according to claim 1.   The display filter according to claim 11, wherein the antireflection film is provided as an outermost layer.

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