JP2006163151A - Antireflection film and filter for display having this antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film which is capable of satisfactorily reducing interference fringes even when a transparent substrate having a relatively high refractive index is used, costs manufacture expenses little and, particularly, is capable of reducing interference fringes produced by three-wavelength fluorescent light in particular. <P>SOLUTION: In the antireflection film useful for a front surface filter of plasma display panel and the like, an intermediate layer, a hard coat layer and a low refractive index layer are laminated in the order on a transparent substrate and the following expressions are satisfied; an expression (1) n<SB>1</SB>>n<SB>2</SB>>n<SB>3</SB>, an expression (2) ¾n<SB>2</SB>-(n<SB>1</SB>+n<SB>3</SB>)/2¾≤0.07, an expression (3) 1.56≤n<SB>1</SB>≤1.71 and an expression (4) 1.50≤n<SB>2</SB>≤1.70, 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 65 to 103 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, the antireflection hard coat sheet which uses a triacetyl cellulose film (refractive index: 1.49) as a transparent substrate 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.

  Furthermore, the hard coat sheet having the structure described in Patent Document 1 has to increase the refractive index of the hard coat layer, which requires a large amount of filler, which increases the manufacturing cost. It was.

  Furthermore, in recent years, so-called three-wavelength fluorescent lamps have been used in homes and offices. This three-wavelength fluorescent lamp has output peaks in three light wavelength regions corresponding to the RGB regions (for example, three wavelength regions near 450 nm, 545 nm, and 610 nm), and is energy-saving and natural. It is becoming popular as lighting that brings in light. However, when the appearance of the antireflection film coated and formed is observed under such illumination, the interference fringes generated by the peak wavelength of the three-wavelength fluorescent lamp are generated corresponding to the light of the peak wavelength. In particular, it has become clear that it may be particularly noticeable visually. For this reason, in order to view a good image on a PDP display characterized by a natural reddish color tone, a PDP front filter using the antireflection film as an antireflection layer causes a particular inconvenience.

  Therefore, the object of the present invention is to have good interference fringe reduction characteristics even when a material having a relatively high refractive index such as PET (polyethylene terephthalate) (for example, refractive index 1.65) is used as the transparent substrate. Another object of the present invention is to provide an antireflection film useful for a front filter of a plasma display panel (PDP) or other display, which does not cause an increase in manufacturing cost due to the use of a large amount of filler in a hard coat layer.

  Another object of the present invention is to provide an antireflection film useful for a front display filter of a plasma display panel (PDP) and other displays in which the interference fringes generated in a three-wavelength fluorescent lamp are reduced.

  It is another object of the present invention to provide a front filter for a display having an antireflection film having the above characteristics.

The present inventors have stated that the above purpose is
An antireflection film in which a low refractive index layer having a refractive index lower than that of an intermediate layer, a hard coat layer, and a hard coat layer is sequentially laminated on a transparent substrate,
The following formulas (1) to (4):
n ₁ > n ₂ > n ₃ (1)
| N ₂ − (n ₁ + n ₃ ) /2|≦0.07 (2)
1.56 ≦ n ₁ ≦ 1.71 (3)
1.50 ≦ n ₂ ≦ 1.70 (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)
The filling,
It has been found that the thickness d (nm) of the intermediate layer is achieved by an antireflection film characterized by being in the range of 65 to 103 nm.

The refractive index n ₁ of the transparent substrate is generally in the range of 1.56 to 1.71, preferably in the range of 1.60 to 1.66, particularly preferably in the range of 1.64 to 1.65. The refractive index n ₂ of the intermediate layer is generally in the range of 1.50 to 1.70, preferably in the range of 1.54 to 1.65, particularly preferably in the range of 1.55 to 1.62. By selecting such a range and combining it with the thickness of the intermediate layer, the interference fringe reduction effect of the present invention can be exhibited.

  The range of 65 to 103 nm of the thickness d (nm) of the intermediate layer described above corresponds to the peak wavelength regions of three lights corresponding to the RGB regions included in the three-wavelength fluorescent lamp considered in the present invention (for example, (Three wavelength regions near 450 nm, 545 nm, and 610 nm), and by setting such a thickness d (nm), it is possible to cancel light reflected at each specific peak wavelength. It becomes. Therefore, in the overall design of the reflective film and the front filter for display, it is possible to dramatically reduce interference fringes corresponding to each specific peak wavelength that becomes an obstacle.

The thickness d (nm) of this intermediate layer is expressed by the following formula (5):
d = λ / (4 × n ₂ ) (5)
(Where λ is the wavelength (nm) of the light targeted for interference fringe reduction)
The range corresponds to the value obtained by. That is, the range of 65 to 103 nm, which is the range of the thickness d (nm) of the intermediate layer of the present invention, is composed of the range of 65 to 77 nm, the range of 78 to 93 nm, and the range of 88 to 103 nm. There are three ranges of the three wavelengths corresponding to the RGB regions of the three-wavelength fluorescent lamp considered in the present invention as the wavelength λ (nm) of the light of the above formula (5). This is a range that can be obtained by selecting and applying values corresponding to three wavelength regions in the peak wavelength region, that is, around 450 nm, around 545 nm, and around 610 nm. The values of the peak wavelengths of the three lights corresponding to the RGB regions included in the three-wavelength fluorescent lamp are slightly different depending on the design of the respective fluorescent lamps. Of course, it is also possible to apply to the above. It is naturally possible to apply a value intentionally shifted from the true center value of the peak wavelength to the above equation (5).

In the above formula (2), the following formula:
| N ₂ − (n ₁ + n ₃ ) / 2 |
The value determined by is generally 0.07 or less, preferably 0.05 or less, particularly preferably 0.03 or less. By reducing the difference in the refractive index of each layer according to this standard, an antireflection film with particularly enhanced interference fringe generation suppression effect and antireflection effect can be obtained.

The refractive index n ₃ of the hard coat layer is generally in the range of 1.49 to 1.60, preferably in the range of 1.51 to 1.58, particularly preferably in the range of 1.53 to 1.56. By using a refractive index selected from such a range, preferred implementation of the present invention is possible.

Moreover, it is preferable from the transparency, flexibility, etc. that the said transparent base material is a PET film. When the PET film is used, the refractive index n ₂ of the intermediate layer is set to a value of 1.65 or less corresponding to the refractive index of the PET film.

  The low refractive index layer may contain a resin in which hollow silica (porous 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 using such a filter, it is possible to dramatically reduce interference fringes corresponding to a specific peak wavelength. 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, even when a material having a relatively high refractive index such as PET (polyethylene terephthalate) (for example, a refractive index of 1.65) is used as a transparent base material, it is called an oil stain as well as an antireflection effect. An antireflection film useful for a front display filter of a plasma display panel (PDP) or other display is obtained that reduces interference fringes and does not cause an increase in manufacturing cost due to the use of a large amount of filler in the hard coat layer. be able to.

  Moreover, according to the present invention, an antireflection film particularly suitable for reducing interference fringes generated at a specific peak wavelength of a so-called three-wavelength fluorescent lamp can be obtained. This antireflection film does not produce interference fringes that occur at specific peak wavelengths that are visually unpleasant even in an environment where a so-called three-wavelength fluorescent lamp is used as illumination. A display filter using this antireflection film as an antireflection layer enables viewing of a natural color image. It is particularly suitable for use in a PDP display characterized by a natural reddish 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 and outdoors, display windows for instruments and devices, and the like.

  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, an intermediate layer 13 having adhesiveness on a transparent substrate layer 14, a hard coat layer 12 having a certain hardness for protecting the transparent substrate, and a refractive index lower than that of the hard coat layer. An antireflection film in which the low refractive index layer 11 is sequentially laminated is shown. 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 is an antireflection film in which an intermediate layer 13, a hard coat layer 12, and a low refractive index layer 11 having a refractive index lower than that of the hard coat layer are sequentially laminated on the transparent base layer 14, The following formulas (1) to (4):
n ₁ > n ₂ > n ₃ (1)
| N ₂ − (n ₁ + n ₃ ) /2|≦0.07 (2)
1.56 ≦ n ₁ ≦ 1.71 (3)
1.50 ≦ n ₂ ≦ 1.70 (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 65 to 103 nm.

  The thickness, refractive index, material, etc. of the intermediate layer will be described below.

  The range of 65 to 103 nm, which is the range of the thickness d (nm) of the intermediate layer, is preferably in the range of 65 to 77 nm, 78 to 93 nm, or 88 to 103 nm. These three ranges are the three light peak wavelength regions corresponding to the RGB regions included in the three-wavelength fluorescent lamp considered in the present invention (for example, three wavelengths near 450 nm, 545 nm, and 610 nm). With such a thickness d (nm), the light reflected at each specific peak wavelength can be canceled out. Therefore, in the overall design of the reflective film and the front filter for display, it is possible to dramatically reduce interference fringes corresponding to each specific peak wavelength that becomes an obstacle.

The thickness d (nm) of this intermediate layer is expressed by the following formula (5):
d = λ / (4 × n ₂ ) (5)
(Where λ is the wavelength (nm) of the light targeted for interference fringe reduction)
The range corresponds to the value obtained by. That is, the three ranges forming the range of the thickness d (nm) of the intermediate layer of the present invention are the three-wavelength type considered in the present invention as the wavelength λ (nm) of the light of the above formula (5). It can be obtained by selecting and applying values corresponding to the three peak wavelength regions of RGB corresponding to the RGB regions of the fluorescent lamp, that is, the three wavelength regions near 450 nm, 545 nm, and 610 nm. It is a range. The values of the peak wavelengths of the three lights corresponding to the RGB regions included in the three-wavelength fluorescent lamp are slightly different depending on the design of the respective fluorescent lamps. Of course, it is also possible to apply to the above. It is naturally possible to apply a value intentionally shifted from the true center value of the peak wavelength to the above equation (5).

  The thickness d (nm) of the intermediate layer can be set to a value in the range of 65 to 103 nm. From the range of 65 to 77 nm, the range of 78 to 93 nm, and the range of 88 to 103 nm, Furthermore, it is possible to set the value within a selected range as follows.

  The range of 65 to 77 nm of the thickness d (nm) of the intermediate layer is preferably in the range of 68 to 75 nm, particularly preferably in the range of 70 to 73 nm, so that the specific peak wavelength centered at 450 nm is It is possible to effectively suppress the occurrence of interference fringes.

  The range of 78 to 93 nm of the thickness d (nm) of the intermediate layer is preferably in the range of 83 to 91 nm, particularly preferably in the range of 85 to 89 nm, with respect to a specific peak wavelength centered at 545 nm. It is possible to effectively suppress the occurrence of interference fringes.

  The range of 88 to 103 nm of the thickness d (nm) of the intermediate layer is preferably in the range of 92 to 101 nm, particularly preferably in the range of 94 to 99 nm, so that the specific peak wavelength centered at 610 nm is It is possible to effectively suppress the occurrence of interference fringes.

The refractive index n ₂ of the intermediate layer is generally in the range of 1.50 to 1.70, preferably in the range of 1.54 to 1.65, particularly preferably in the range of 1.55 to 1.62. By selecting such a range and combining it with the thickness of the intermediate layer, the interference fringe reduction effect of the present invention can be exhibited.

The value of the refractive index n ₂ of the intermediate layer is expressed by the following formula:
| N ₂ − (n ₁ + n ₃ ) / 2 |
In general, it is preferable that the value obtained by the above is 0.07 or less, preferably 0.05 or less, particularly 0.03 or less. By setting the value of the refractive index n ₂ of the intermediate layer according to this standard and reducing the difference in the refractive index of each layer, an antireflection film with particularly enhanced interference fringe generation suppression effect and antireflection effect can be obtained. .

  As the material of the intermediate layer, any material can be used without any limitation as long as it has a refractive index that can achieve the above-described relationship of refractive index between the layers of the present invention and can be bonded with a predetermined thickness. It is. 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 intermediate layer 13 is laminated on the transparent substrate layer 14. The refractive index, material, thickness, etc. of this transparent substrate layer will be described below.

The refractive index n ₁ of the transparent substrate layer is generally in the range of 1.56 to 1.71, preferably in the range of 1.60 to 1.66, particularly preferably in the range of 1.64 to 1.65. By using such a transparent substrate layer having a relatively low refractive index, it is possible to effectively cancel interference fringes while enabling the use of a hard coat layer having a relatively low refractive index. The superiority of the invention can be exhibited particularly.

Examples of the material for the transparent substrate layer include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), acrylic resin, polycarbonate; polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA). ), 4-fluorinated ethylene-6-fluorinated propylene copolymer (FEP), 2-ethylene-4-fluorinated ethylene copolymer (ETFE), poly-3-fluoroethylene chloride (PCTFE), polyvinylidene fluoride Examples thereof include films made of fluororesins such as (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. In a preferred embodiment of the present invention, when a PET film is used, the refractive index n ₂ of the intermediate layer is set to a value of 1.65 or less corresponding to the refractive index of the PET film.

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

  On the transparent intermediate layer 13, a hard coat layer 12 is provided. The refractive index, material, thickness, etc. of the hard coat layer will be described below.

The refractive index n ₃ of the hard coat layer is generally in the range of 1.49 to 1.60, preferably in the range of 1.51 to 1.58, particularly preferably in the range of 1.53 to 1.56. By using a refractive index selected from such a range, preferred implementation of the present invention is possible. By using such a hard coating layer having a relatively low refractive index, the reflection of the present invention does not increase the manufacturing cost without using a large amount of filler in the hard coating layer. The superiority of the prevention film can be exhibited.

  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 is preferably 1 to 20 μm (particularly 1 to 15 μm).

  On the hard coat layer 12, a low refractive index layer 11 is provided. The material, refractive index, thickness, etc. of the low refractive index layer will be described below.

  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 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 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 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 the formation of a PET film (refractive index: 1.65, 150 μm thickness) as a transparent substrate, a sulfur-modified acrylic resin was cast on this 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 87 nm. Next, 75 parts by mass of dipentaerythritol hexaacrylate (DPHA) (trade name DPHA, manufactured by Nippon Kayaku Co., Ltd.) as a polyfunctional acrylate monomer, 25 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 photopolymerization initiator (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) as an agent was prepared and applied on the intermediate layer. 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 3 μm). On this, a fluororesin layer (refractive index 1.43, thickness 90 nm) was formed as a low refractive 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 Production was conducted in the same manner as Example 1 except that the low refractive layer was formed as follows. That is, first, similarly to Example 1, a transparent base material, an intermediate layer, and a hard coat layer were laminated in order.

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 photopolymerization initiator (trade name Irgacure 184, manufactured by Ciba Specialty Chemicals) as a polymerization initiator Then, 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).

  Furthermore, this was bonded to a glass plate in the same manner as in Example 1 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 the thickness of the intermediate layer was changed from 87 nm to 40 nm.

  Furthermore, this was bonded to a glass plate in the same manner as in Example 1 to produce a display filter for interference fringe prevention experiments.

[Comparative Example 2]
Production of Antireflection Film and Display Filter of Comparative Example 2 Example 1 except that the refractive index of the intermediate layer was changed from 1.57 to 1.51 by adjusting the modification of the sulfur-modified acrylic resin. A film was produced in the same manner as above.

  Furthermore, this was bonded to a glass plate in the same manner as in Example 1 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 the thickness of the intermediate layer was changed from 87 nm to 40 nm.

  Further, this was bonded to a glass plate in the same manner as in Example 2 to produce a display filter for interference fringe prevention experiments.

[Comparative Example 4]
Production of Antireflection Film and Display Filter of Comparative Example 4 Example 2 except that the refractive index of the intermediate layer was changed from 1.57 to 1.51 by adjusting the modification of the sulfur-modified acrylic resin. A film was produced in the same manner as above.

  Further, this was bonded to a glass plate in the same manner as in Example 2 to produce a display filter for interference fringe prevention experiments.

中間層厚さ 中間層 目視評価
ｄ（ｎｍ） 屈折率ｎ₂

実施例１ ８７ １．５７ ○
実施例２ ８７ １．５７ ○
比較例１ ４０ １．５７ ×
比較例２ ８７ １．５１ ×
比較例３ ４０ １．５７ ×
比較例４ ８７ １．５１ ×

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.

Intermediate layer thickness Intermediate layer Visual evaluation
d (nm) Refractive index n ₂

Example 1 87 1.57 ○
Example 2 87 1.57 ○
Comparative Example 1 40 1.57 ×
Comparative Example 2 87 1.51 ×
Comparative Example 3 40 1.57 ×
Comparative Example 4 87 1.51 ×

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. Moreover, what used the ultraviolet curable resin containing a hollow silica as a low refractive index layer was excellent in hardness compared with the thing by a fluororesin.

  From the above, the antireflection film of the present invention and the display panel using the antireflection film have excellent characteristics that particularly reduce annoying interference fringes when a three-wavelength fluorescent lamp is used for illumination. all right.

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 (7)

An antireflection film in which a low refractive index layer having a refractive index lower than that of an intermediate layer, a hard coat layer, and a hard coat layer is sequentially laminated on a transparent substrate,
The following formulas (1) to (4):
n ₁ > n ₂ > n ₃ (1)
| N ₂ − (n ₁ + n ₃ ) /2|≦0.07 (2)
1.56 ≦ n ₁ ≦ 1.71 (3)
1.50 ≦ n ₂ ≦ 1.70 (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)
The filling,
An antireflection film, wherein the intermediate layer has a thickness d (nm) in the range of 65 to 103 nm. The antireflection film according to claim 1, wherein the refractive index n ₃ of the hard coat layer is in the range of 1.49 to 1.60. The antireflection film according to claim 1, wherein a PET film is used as the transparent substrate, and the refractive index n ₂ of the intermediate layer is a value of 1.65 or less.   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 4, comprising an ultraviolet curable resin as the resin.   A display filter comprising the antireflection film according to claim 1.   The display filter according to claim 6, wherein the antireflection film is provided as an outermost layer.

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