JP2006163156A - Antireflection film and filter for display having the antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film which suppresses a restriction with respect to wavelength of light to the minimum, is capable of satisfactorily reducing interference fringes in various indoor illumination actually used and is useful for front surface filter etc. of plasma display (PDP) and other displays. <P>SOLUTION: In the antireflection film, an intermediate layer, a hard coat layer having a high refractive index and a low refractive index layer having a refractive index lower than that of the hard coat layer are laminated in the order on a transparent substrate and the following expressions are satisfied; an expression (1) n<SB>1</SB>≥1.55, an expression (2) n<SB>3</SB>≥1.55, an expression (3) 0<¾n<SB>1</SB>-n<SB>2</SB>¾<0.1 and an expression (4) 0<¾n<SB>3</SB>-n<SB>2</SB>¾<0.1, wherein n<SB>1</SB>is refractive index of the transparent substrate, n<SB>2</SB>is refractive index of the intermediate layer and n<SB>3</SB>is refractive index of the hard coat layer. Therein, the thickness (d) (nm) of the intermediate layer falls into the range of 5 to 40 nm. <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) and other displays, and a front filter for a display having the antireflection film.

  Usually, a front filter is always used for a PDP. This front filter is intended for cutting near infrared rays, improving color reproducibility (emission color purity improvement), electromagnetic wave shielding, improving contrast in a bright place (antireflection), protecting a light emitting panel, blocking heat from the light emitting panel, and the like.

  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. Further, in order to make the light emitted from the light emitting panel of the PDP feel a natural color for human vision, there is a demand for improvement in color reproducibility (light emission color purity improvement) 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, it is desirable that the heat generated by the light emitting panel of the PDP is 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, and even if the product is damaged, it is desirable that the fragments are not scattered.

  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.

  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 is obtained by laminating a high refractive index layer 32 having a hard coat property and a low refractive index layer 31 having a lower refractive index than the high refractive index layer 32 having a hard coat property on a transparent base material 33, It has a role of preventing the visibility from being deteriorated due to reflection of external light incident from the low refractive index layer 31 side.

  In order to improve the antireflection effect in the antireflection film having the structure as shown in FIG. 3, it is theoretically preferable that the refractive index difference between the high refractive index layer and the low refractive index layer is large. However, there is a practical limit to reducing the refractive index of the low refractive index layer while satisfying other characteristics required for the low refractive index layer, that is, adhesiveness and hardness with the high refractive index layer. . For this reason, the high refractive index layer is increased in refractive index, which increases the difference in refractive index between the transparent substrate and the high refractive index layer. However, for this reason, interference fringes, also called oil stains, are observed due to a very slight non-uniformity in the thickness of the high refractive index layer. This interference fringe is a problem because it presents a color unrelated to the image displayed on the display and degrades the display quality of the display.

  As an antireflection film that prevents such interference fringes, Patent Document 1 (Japanese Patent Laid-Open No. 2003-75603) discloses an antireflection hard coat sheet for liquid crystal displays. This antireflection hard coat sheet is obtained by laminating a medium refractive index layer, a high refractive index layer, and a low refractive index layer in this order on a transparent substrate. For example, in the antireflection film having the structure of FIG. 3, the refractive index is higher than that of the high refractive index layer 32 and higher than that of the low refractive index layer 33 between the transparent base material 33 and the high refractive index layer 32. The structure has a small medium refractive index layer. In the example of Patent Document 1, a triacetyl cellulose film (refractive index: 1.49) is used as a transparent substrate, and a medium refractive index layer (refractive index 1.59) having a thickness of 86 nm is provided. A hard coat sheet is disclosed.

JP 2003-75603 A

  The present inventors have used an antireflection film for display with reduced interference fringes as described above, in particular, as a means for reducing interference fringes, between the transparent substrate and the high refractive index layer in the structure as shown in FIG. We have intensively studied by providing an intermediate layer (adhesive layer) and controlling the relationship between the layer thickness and the refractive index with respect to the wavelength of light.

  As a result of the investigation, the antireflection hard coat sheet having the structure described in Patent Document 1 uses a material having a relatively low refractive index such as a triacetyl cellulose film (for example, refractive index 1.49) as a transparent substrate. In this case, although it has a relatively good interference fringe prevention function, it is very good when a material having a relatively high refractive index such as PET (polyethylene terephthalate) (refractive index 1.65) is used. It was found that it does not show any properties.

  Further, the antireflection hard coat sheet having the structure described in Patent Document 1 has a characteristic that interference fringe reduction strongly depends on the wavelength of light incident on the antireflection surface from the outside, and is therefore actually used. It turned out that it does not necessarily have a sufficient interference fringe reduction characteristic with respect to all of various indoor lighting.

  Accordingly, an object of the present invention is to provide a plasma display panel (PDP) in which interference fringes are sufficiently reduced even when a material having a relatively high refractive index such as PET (polyethylene terephthalate) is used as a transparent substrate. An object of the present invention is to provide an antireflection film useful for a front filter of other displays.

  It is another object of the present invention to provide a plasma display panel (PDP) or other display in which restrictions on the wavelength of light are minimized, and interference fringes are sufficiently reduced in various indoor lighting used in practice. Another object is to provide an antireflection film useful for a front filter or the like.

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

The present inventors have stated that the above purpose is
An antireflection film in which an intermediate layer, a hard coat layer having a high refractive index, and a low refractive index layer having a lower refractive index than the hard coat layer are sequentially laminated on a transparent substrate,
The following formulas (1) to (4):
n ₁ ≧ 1.55 (1)
n ₃ ≧ 1.55 (2)
_{0 <| n 1 -n 2 |} <0.1 (3)
_{0 <| n 3 -n 2 |} <0.1 (4)
(Where n ₁ is the refractive index of the transparent substrate, n ₂ is the refractive index of the intermediate layer, and n ₃ is the refractive index of the hard coat layer)
And the thickness d (nm) of the intermediate layer is found to be in the range of 5 to 40 nm.

  By providing such an intermediate layer, an antireflection film with sufficiently reduced interference fringes can be obtained even when the refractive index of a layer such as a hard coat layer is increased.

The value of the above formula | n ₁ −n ₂ | is generally 0.1 or less, preferably 0.09 or less, and particularly preferably 0.08 or less. A smaller value is preferable in terms of reducing interference fringes.

The value of the above formula | n ₃ −n ₂ | is generally 0.1 or less, preferably 0.08 or less, and particularly preferably 0.06 or less. A smaller value is preferable in terms of reducing interference fringes.

  The thickness d (nm) of the intermediate layer can be in the range of 5 to 40 nm, but is generally in the range of 5 to 30 nm, preferably in the range of 10 to 30 nm, and particularly preferably in the range of 15 to 25 nm. . A smaller value of thickness d (nm) is preferable from the viewpoint of reducing interference fringes, but from the viewpoint of maintaining the adhesive strength required for the intermediate layer as an adhesive layer, a larger thickness is preferable in this range.

The antireflection film has the following formula (5):
n ₁ ≧ n ₃ (5)
(However, n ₁ and n ₃ have the same meaning as in the above formula)
It can implement suitably in the aspect which satisfy | fills.

The refractive index n ₃ of the hard coat layer in the above formula is generally 1.55 or more, preferably 1.57 or more, and particularly preferably 1.59 or more. The refractive index n ₁ of the transparent substrate in the formula takes a value not less than the value of n ₃ . By dealing with a larger value of the refractive index in this way, it is possible to take advantage of the present invention that interference fringes can be sufficiently reduced even when the refractive index of the transparent substrate is increased.

Further, as the range thereof, the refractive index n ₁ of the transparent substrate can be generally in the range of 1.55 to 1.70, preferably in the range of 1.59 to 1.68, particularly 1 The refractive index n ₃ of the hard coat layer can generally be in the range of 1.55 to 1.70, preferably in the range of 1.59 to 1.68. In particular, the range of 1.63-1.66 is preferable. With respect to the refractive index in such a range, the refractive index and thickness of the intermediate layer of the present invention can be suitably selected.

Various transparent substrates can be used as the transparent substrate, but a PET film is preferable from the viewpoint of transparency and flexibility. In this case, the refractive index of the PET film is a refractive index of usually about 1.65, as the refractive index n ₃ of the refractive index of the intermediate layer n ₂ and the hard coat layer is approached, it becomes possible to reduce the interference fringes, preferable.

The hard coat layer can preferably contain a resin in which metal oxide fine particles are dispersed. As the metal oxide fine particles, ITO, ATO, Sb ₂ O ₃ , SbO ₂ , In ₂ O ₃ , SnO ₂ , ZnO, TiO ₂ , ZrO ₂ , CeO ₂ , Al ₂ O ₃ , Y ₂ O ₃ , La One or more metal oxide fine particles selected from the group consisting of ₂ O ₃ , LaO ₂ and Ho ₂ O ₃ can be used. ITO (indium oxide / tin oxide), ATO (antimony oxide / tin oxide), Sb ₂ O ₃ , SbO ₂ , In ₂ O ₃ , SnO ₂ , ZnO are particularly useful for imparting electrical conductivity to the hard coat layer. TiO ₂ , ZrO ₂ , CeO ₂ , Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , LaO ₂ and Ho ₂ O ₃ are particularly useful for increasing the refractive index of the hard coat layer. is there. Accordingly, the refractive index of the hard coat layer can be adjusted, and charging can be prevented by imparting conductivity. Various resins can be used as this resin, but an ultraviolet curable resin is preferable from the viewpoints of hardness after curing and handling in manufacturing.

  The low refractive index layer can contain a resin in which hollow silica is dispersed, and thereby the refractive index of the low refractive index layer can be adjusted. In addition, it is preferable to use an ultraviolet curable resin as the resin from the viewpoint of improving the hardness.

  The antireflection film containing the low refractive index layer as the outermost layer is a preferred embodiment of the present invention.

  Furthermore, this invention exists also in the filter for displays containing the said antireflection film. By setting it as such a filter, it becomes possible to obtain the display filter which has the advantage of this invention with which interference fringes were reduced. In particular, the display filter including the antireflection film as the outermost layer is a preferred embodiment of the present invention that takes advantage of the antireflection and interference fringe reduction characteristics.

  According to the present invention, for example, even when a material having a relatively high refractive index, such as PET (polyethylene terephthalate), is used, an antireflection film with reduced interference fringes called so-called 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. FIG. 1 shows an antireflection film having a low refractive index layer 11, a hard coat layer 12, an intermediate layer 13, and a transparent substrate layer 14. 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.

This antireflection film has the following formulas (1) to (4):
n ₁ ≧ 1.55 (1)
n ₃ ≧ 1.55 (2)
_{0 <| n 1 -n 2 |} <0.1 (3)
_{0 <| n 3 -n 2 |} <0.1 (4)
(Where n ₁ is the refractive index of the transparent substrate layer 14, n ₂ is the refractive index of the intermediate layer 13, and n ₃ is the refractive index of the hard coat layer 12)
And the condition that the thickness d (nm) of the intermediate layer 13 is 40 nm or less is satisfied. In this way, an antireflection film with sufficiently reduced interference fringes can be obtained even when the refractive index of a layer such as a hard coat layer is increased.

In a more preferred embodiment, the value of the above formula | n ₁ −n ₂ | is generally 0.1 or less, preferably 0.09 or less, particularly preferably 0.08 or less. A smaller value is preferable in terms of reducing interference fringes. The value of the above formula | n ₃ −n ₂ | is generally 0.1 or less, preferably 0.08 or less, and particularly preferably 0.06 or less. A smaller value is preferable in terms of reducing interference fringes.

The antireflection film has the following formula (5):
n ₁ ≧ n ₃ (5)
(However, n ₁ and n ₃ have the same meaning as in the above formula)
It can implement suitably in the aspect which satisfy | fills.

The refractive index n ₃ of the hard coat layer in the above formula is generally 1.55 or more, preferably 1.57 or more, and particularly preferably 1.59 or more. The refractive index n ₁ of the transparent substrate in the formula takes a value equal to or greater than the value of n ₃ and is generally 1.55 or more, preferably 1.57 or more, and particularly preferably 1.59 or more. By dealing with a larger value of the refractive index in this way, it is possible to take advantage of the present invention that interference fringes can be sufficiently reduced even when the refractive index of the transparent substrate is increased.

Further, as the range, the refractive index n ₁ of the transparent substrate can be in the range of 1.55 to 1.70, but is generally in the range of 1.59 to 1.68, preferably 1. The refractive index n ₃ of the hard coat layer can be in the range of 1.55 to 1.70, but is generally in the range of 1.59 to 1.68, Preferably it is the range of 1.63-1.66. With respect to the refractive index in such a range, the refractive index and thickness of the intermediate layer of the present invention can be suitably selected.

  As the material of the transparent substrate layer 14 in FIG. 1, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), acrylic resin, polycarbonate; polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy Polymer (PFA), 4-fluorinated ethylene-6-fluorinated propylene copolymer (FEP), 2-ethylene-4-fluorinated ethylene copolymer (ETFE), poly-3-fluoroethylene chloride (PCTFE) And films of fluororesins such as polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF). A PET film is particularly preferable from the viewpoints of transparency and flexibility, and the present invention can be suitably applied to PET having a refractive index of 1.65.

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

Furthermore, in a preferred embodiment of the present invention, the refractive index n ₂ of the intermediate layer is expressed by the following formulas (6) and (7):
n ₁ ≧ n ₂ (6)
n ₃ ≧ n ₂ (7)
It is a value that satisfies By setting it as such a value, an intermediate | middle layer can be installed more easily.

  An intermediate layer 13 is provided on the transparent base layer 14 in FIG. As the material of the intermediate layer, a material having a refractive index that can achieve the above-described refractive index relationship between the respective layers of the present invention, that is, a refractive index of 1.55 or more, a transparent base material layer, a hard coat layer, Any material having a close refractive index and capable of being bonded can be used without particular limitation. 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.

  The thickness d (nm) of the intermediate layer 13 can generally be in the range of 5 to 40 nm, but is preferably in the range of 5 to 30 nm, and particularly preferably in the range of 10 to 30 nm. A smaller value of thickness d (nm) is preferable from the viewpoint of reducing interference fringes, but from the viewpoint of maintaining the adhesive strength required for the intermediate layer as an adhesive layer, a larger thickness is preferable in this range.

  A hard coat layer 12 is provided on the transparent intermediate layer 13 in FIG. The hard coat layer is a layer made of a cured film of a thermosetting resin or an ultraviolet curable resin, and in particular, the hard coat layer can be provided on the transparent substrate layer very easily by using an ultraviolet curable resin. it can.

  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.

In a preferred embodiment, the hard coat layer includes, as the metal oxide fine particles, ITO (indium oxide / tin oxide), ATO (antimony oxide / tin oxide), Sb ₂ O ₃ , SbO ₂ , In ₂ O. ₃ , one or more selected from the group consisting of SnO ₂ , ZnO, TiO ₂ , ZrO ₂ , CeO ₂ , Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , LaO ₂ and Ho ₂ O ₃ The metal oxide fine particles can be used. ITO, ATO, Sb ₂ O ₃ , SbO ₂ , In ₂ O ₃ , SnO ₂ , and ZnO are particularly useful for imparting conductivity to the hard coat layer, and include TiO ₂ , ZrO ₂ , CeO ₂ , Al _2. O ₃ , Y ₂ O ₃ , La ₂ O ₃ , LaO ₂ and Ho ₂ O ₃ are particularly useful for increasing the refractive index of the hard coat layer. Accordingly, the refractive index of the hard coat layer can be adjusted, and charging can be prevented by imparting conductivity.

  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 thickness of the hard coat layer 12 is preferably 1 to 20 μm (particularly 1 to 15 μm).

  A low refractive index layer 11 is provided on the hard coat layer 12 in FIG. The low refractive index layer 11 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 11 can also 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. It is.

  Since such an organic thin film is generally a low refractive index thin film having a refractive index of 1.3 to 1.6, it is suitable in the present invention.

  Further, preferably, by filling a filler such as hollow silica (porous silica), the refractive index can be lowered and the antireflection performance can be improved. In particular, since hollow silica is an inorganic compound filler, a decrease in refractive index due to this is preferable in that a harder low refractive index thin film can be formed as compared with a decrease in refractive index due to an organic additive.

  Since the hollow silica is hollow and contains air inside, it has a very low refractive index (about 1.34 to 1.44) compared to ordinary silica (refractive index: about 1.46). This can be created by covering the surface of porous silica fine particles with an organosilicon compound or the like and closing the pore entrance. The average particle diameter of the hollow silica 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 size, the better. However, in addition to the above-mentioned contribution to lowering the refractive index, hollow silica fine particles tend to aggregate, especially when the particle size is smaller than about 0.5 nm. Uniform dispersion is not easy.

  The thickness of the low refractive index layer 11 is preferably an optical film thickness within a range in which the antifouling function can be obtained in order to achieve both the antireflection function and the antifouling function, and in the range of 50 to 500 nm. 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 having a high refractive index 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. be able to.

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

[Example 1]
Production of Antireflection Film and Display Filter of the Present Invention Immediately after forming a PET film (refractive index: 1.65, 150 μm thickness) as a transparent substrate, a sulfur-modified acrylic resin is cast on the PET film. Were rolled and bonded to form an intermediate layer (intermediate refractive index layer) having a refractive index of 1.57 and a thickness of 20 nm. Next, as a polyfunctional acrylate monomer, 40 parts by mass of dipentaerythritol hexaacrylate (DPHA) (trade name DPHA, manufactured by Nippon Kayaku Co., Ltd.), 60 parts by mass of zirconia, 100 parts by mass of MEK, 100 parts by mass of toluene, polymerization start A coating liquid containing 4 parts by mass of a photoinitiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) was prepared as an agent, and applied onto the above intermediate layer. 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 1.63, thickness 3 μm). A fluororesin layer (refractive index 1.43, thickness 90 nm) was formed thereon as a low refractive index layer.

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

[Example 2]
Production of Antireflection Film and Display Filter of the Present Invention In the same manner as in Example 1, an intermediate layer (intermediate refractive index layer) made of sulfur-modified acrylic resin was formed on a transparent substrate made of PET film. Next, as in Example 1, a hard coat layer made of an ultraviolet curable resin was formed. Next, 2 parts by mass of DPHA, 2 parts by mass of porous silica (hollow silica) (particle size 20 nm), 0.1 parts by mass of a photoinitiator (manufactured by Ciba Specialty Chemicals, trade name Irgacure 184) as a polymerization initiator, A coating solution containing 100 parts by mass of MIBK 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 1.43, thickness 90 nm).

  Further, this was bonded to a glass plate with a thickness of 2.5 mm to produce a display filter for interference fringe prevention experiments.

[Comparative Example 1]
Production of Antireflection Film and Display Filter of Comparative Example 1 A film was produced in the same manner as in Example 1 except that a layer having a refractive index of 1.57 and a thickness of 80 nm was formed as an intermediate layer.

  Further, this was bonded to a glass plate with a thickness of 2.5 mm to produce a display filter for interference fringe prevention experiments.

[Comparative Example 2]
Production of antireflection film and display filter of Comparative Example 2 As an intermediate layer, except for forming a 20 nm thick layer having a refractive index of 1.51 by adjusting the modification of the sulfur-modified acrylic resin. A film was prepared as in Example 1.

  Further, this was bonded to a glass plate with a thickness of 2.5 mm to produce a display filter for interference fringe prevention experiments.

[Comparative Example 3]
Production of Antireflection Film and Display Filter of Comparative Example 3 A film was produced in the same manner as in Example 2 except that a layer having a refractive index of 1.57 and a thickness of 80 nm was formed as an intermediate layer.

  Further, this was bonded to a glass plate with a thickness of 2.5 mm to produce a display filter for interference fringe prevention experiments.

[Comparative Example 4]
Production of antireflection film and display filter of Comparative Example 4 As an intermediate layer, except for forming a 20 nm thick layer having a refractive index of 1.51 by adjusting the modification of the sulfur-modified acrylic resin. A film was prepared as in Example 2.

  Further, this was bonded to a glass plate with a thickness of 2.5 mm to produce a display filter for interference fringe prevention experiments.

目視評価

実施例１ ○
実施例２ ○
比較例１ ×
比較例２ ×
比較例３ ×
比較例４ ×

表１ [Evaluation of interference fringe generation]
The display filters of Examples 1 and 2 and Comparative Examples 1 to 4 were used to prevent reflection on a smooth wall surface in a room using a three-wavelength fluorescent lamp (product name: FHF32EX-N, manufactured by Toshiba) as a ceiling lamp. It was installed so that the film surface was on the indoor side. 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.

Visual evaluation

Example 1 ○
Example 2 ○
Comparative Example 1 ×
Comparative Example 2 ×
Comparative Example 3 ×
Comparative Example 4 ×

Table 1

[result]
In the display panel using the antireflection film of the present invention shown in Example 1 and Example 2, the conspicuous interference fringes are hardly seen, whereas the intermediate layers shown in Comparative Examples 1 to 4 are not visible. Conspicuous interference fringes were clearly visible in display panels using antireflection films with different refractive indices or thicknesses. That is, it was found that the antireflection film of the present invention and the display panel using the same have excellent characteristics for reducing annoying interference fringes.

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 13 Intermediate layer 14 Transparent base material layer 20 Light emission panel 21 Antireflection layer 22 Electromagnetic wave shield layer 23 Transparent substrate 24 Color tone correction filter layer 25 Near-infrared cut layer 31 Low refractive index layer 32 Hard coat property High refractive index layer having 33 transparent substrate

Claims (12)

An antireflection film in which an intermediate layer, a hard coat layer having a high refractive index, and a low refractive index layer having a lower refractive index than the hard coat layer are sequentially laminated on a transparent substrate,
The following formulas (1) to (4):
n ₁ ≧ 1.55 (1)
n ₃ ≧ 1.55 (2)
_{0 <| n 1 -n 2 |} <0.1 (3)
_{0 <| n 3 -n 2 |} <0.1 (4)
(Where n ₁ is the refractive index of the transparent substrate, n ₂ is the refractive index of the intermediate layer, and n ₃ is the refractive index of the hard coat layer)
And the thickness d (nm) of the intermediate layer is in the range of 5 to 40 nm. Formula (5):
n ₁ ≧ n ₃ (5)
The antireflection film according to claim 1, wherein The refractive index n ₁ of the transparent substrate is in the range of 1.55 to 1.70, and the refractive index n ₃ of the hard coat layer is in the range of 1.55 to 1.70. The antireflection film as described in 1.   The antireflection film according to claim 1, wherein the transparent substrate is a PET film.   The antireflection film according to claim 1, comprising a resin in which metal oxide fine particles are dispersed in the hard coat layer. The metal oxide fine particles include ITO, ATO, Sb ₂ O ₃ , SbO ₂ , In ₂ O ₃ , SnO ₂ , ZnO, TiO ₂ , ZrO ₂ , CeO ₂ , Al ₂ O ₃ , Y ₂ O ₃ , La _2. The antireflection film according to claim 5, which is one or more metal oxide fine particles selected from the group consisting of O ₃ , LaO ₂ and Ho ₂ O ₃ .   The antireflection film according to claim 5, wherein the resin in which metal oxide fine particles are dispersed includes an ultraviolet curable resin.   The antireflection film according to claim 1, comprising a resin in which hollow silica is dispersed in the low refractive index layer.   The antireflection film according to claim 8, wherein the resin in which hollow silica is dispersed includes an ultraviolet curable resin.   The antireflection film according to claim 1, comprising the low refractive index layer as an outermost layer.   A display filter comprising the antireflection film according to claim 1. A display filter comprising the antireflection film according to claim 1 as an outermost layer.

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