JP2009204698A - Antireflection base material and method for manufacturing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain enough V-curve restraining effect in an antireflection base material, and to achieve excellent productivity and lower the manufacturing cost in a method for manufacturing it. <P>SOLUTION: This antireflection base material 1 includes a low refractive index layer 5 provided on the base material 2 and containing a low refractive index material 3 and having a refractive index lower than that of the base material 2, and a light absorbing material 4. The low refractive index layer 5 is formed so that the concentration of the light absorbing material 4 is gradually increased as it goes toward the base material 2. The part at the base material 2 side of the low refractive index layer 5 functions as a substantial light absorbing layer, so that the V-curve is effectively restrained and these substantially low refractive index layer and light absorbing layer can be formed in one process to lower the manufacturing cost. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an antireflection substrate provided on the surface of a display or the like and a method for manufacturing the same.

  Conventionally, a multilayer film (hereinafter referred to as an antireflection film) that combines a high refractive index layer and a low refractive index layer is formed on the surface of a display or a side mirror of an automobile, thereby reflecting light on those surfaces. Anti-reflection treatment is performed to prevent it. Such an antireflection film can set the wavelength range of the target to prevent reflection by adjusting the film thickness of each layer, and can increase the difference in refractive index between the high refractive index layer and the low refractive index layer. By doing so, the reflectance in the wavelength region of the target can be reduced.

However, when the difference in refractive index between the high refractive index layer and the low refractive index layer increases, the reflectance in the wavelength region other than the target may increase. For example, when the target is set in the medium wavelength region of a wavelength of 500 to 600 nm, the reflectance in this wavelength region is low, while the reflectance on the short wavelength side of 400 nm or less and the long wavelength side of 700 nm or more is high. Become. That is, the spectral reflectance curve has a so-called V-curve shape in which the intermediate region is low and both sides thereof are high. An antireflection film having such reflectance characteristics makes the color of the reflected light unnatural and is not suitable for use in a display or the like.

Therefore, by forming a light absorption layer having a light absorption effect in the laminated film constituting the antireflection film, the reflectance in the medium wavelength region, the short wavelength region, and the long wavelength region is made uniform, and the V curve is A suppressed reflectance characteristic can be obtained (see, for example, Patent Document 1 or Patent Document 2).
JP 2005-148376 A JP 2005-181544 A

However, the antireflection films described in Patent Document 1 and Patent Document 2 differ between the minimum reflectance and the reflectance of light having a wavelength of 380 nm (reflectance difference R ₃₈₀ ), and reflect the light having a minimum reflectance and light having a wavelength of 780 nm. The difference from the reflectance (reflectance difference R ₇₈₀ ) was 2% or more, and a sufficient V-curve suppression effect was not obtained. In addition to these steps of forming each of the low refractive index layer and the high refractive index layer, these antireflection films are formed in a separate process, so that the light absorption layer is formed at least three times in the manufacturing process. A film process is required, the productivity is poor, and the manufacturing cost may increase.

  The present invention solves the above-described problems, and provides an antireflection substrate and a method for producing the same, in which a reflectance characteristic with a sufficiently suppressed V-curve is obtained, which is excellent in productivity and low in production cost. With the goal.

  In order to solve the above-mentioned problems, the invention of claim 1 is directed to an antireflection base material comprising a low refractive index layer containing a low refractive index material having a lower refractive index than that of the base material. The rate layer includes a light absorbing material, and is formed so that the concentration of the light absorbing material gradually increases toward the substrate.

  A second aspect of the present invention is the anti-reflection base material according to the first aspect, wherein a hard coat containing a material that is substantially the same as or higher in refractive index than the base material between the base material and the low refractive index layer. It further comprises a layer.

  A third aspect of the present invention is the antireflective substrate according to the first or second aspect, wherein the low refractive index material is hollow silica fine particles.

  Invention of Claim 4 is a manufacturing method of the antireflective base material provided with the low-refractive-index layer containing the low-refractive-index material whose refractive index is lower than this base material on a base material, Comprising: Said low-refractive-index material And a coating composition containing a matrix-forming material in which the low refractive index material is dispersed and a light-absorbing material having a specific gravity higher than that of the matrix-forming material.

  According to the first aspect of the present invention, since the portion of the low reflectance layer on the substrate side functions as a substantial light absorption layer, an antireflection substrate having reflectance characteristics with a suppressed V curve can be obtained. In addition, since the substantial low reflectance layer and the light absorption layer are formed in one step, the manufacturing cost can be reduced.

  According to invention of Claim 2, by providing a hard-coat layer, the adhesiveness of the low-refractive-index layer containing a light absorption material becomes good, and durability of an antireflection base material can be improved.

  According to invention of Claim 3, a low refractive index layer can be made low-refractive more and a high antireflection function is obtained.

  According to the invention of claim 4, two layers of a substantial light absorption layer and a low refractive index layer can be formed in one step on the substrate. Therefore, the process for forming the conventional light absorption layer separately is not required, the productivity is good, and the manufacturing cost can be reduced.

  An antireflection substrate and a manufacturing method thereof according to a first embodiment of the present invention will be described with reference to FIG. The antireflection base material 1 of the present embodiment includes a low refractive index layer 5 provided on the base material 2 and including a low refractive index material 3 having a lower refractive index than the base material 2 and a light absorbing material 4. . The low refractive index layer 5 includes a matrix forming material 6 in addition to the low refractive index material 3 and the light absorbing material 4 described above, and the low refractive index material 3 and the light absorbing material 4 are diffused into the matrix forming material 6. Or deposit. In the present embodiment, the low refractive index layer 5 is formed so that the concentration of the light absorbing material 4 gradually increases toward the substrate 2 side.

  The base material 2 has transparency to visible light, and the type thereof is not particularly limited as long as various functional layers can be laminated, but preferably has a refractive index of 1.5 or more and low birefringence. Is used. Examples of the material include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefins such as cyclic polyolefin, polyethylene, polypropylene and polystyrene, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, Examples include films made of resins such as polycarbonate, acrylic resin, triacetylcellulose (TAC), polyethersulfone, or polyetherketone, and these may be used alone or in layers of the same or different types. Further, for example, an inorganic base material such as glass may be used.

  As the transparency of the substrate 2, in the case of a single layer, the light transmittance in the visible region is preferably 80% or more and is preferably colorless and transparent. However, the transparency is not necessarily colorless and transparent. It may be colored to such an extent that the effect of the material 1 is not impaired. The light transmittance in the visible region is preferably high, but may be at least 80% or more. The thickness of the substrate 2 is not particularly limited as long as the transparency is not impaired, but is preferably 12 to 300 μm from the viewpoint of workability. When the thickness is less than 12 μm, the base material 2 is too flexible and tends to be stretched or wrinkled due to the tension during processing. On the other hand, when the thickness exceeds 300 μm, the flexibility of the film is reduced, and continuous winding in each step becomes difficult and workability is also deteriorated.

  As the low refractive index material 3, any translucent material having a refractive index of 1.0 to 1.5 can be used. Preferably, a cavity is formed inside an outer shell (shell) made of silica-based inorganic oxide. The hollow silica fine particle which has is used. By using hollow silica fine particles for the low refractive index material 3, the low refractive index layer 5 can be effectively reduced in refractive index, and a higher antireflection function can be obtained.

  Examples of the silica-based inorganic oxide include a silica single layer, a single layer of a composite oxide composed of silica and an inorganic oxide other than silica, or a double layer obtained by combining these single layers. Note that non-hollow silica-based metal oxide fine particles may be used as the low refractive index material 3. The form of these silica fine particles may be, for example, a powder form, but a sol form is preferably used. When the silica fine particles are used in a sol form, for example, a water-dispersible colloidal silica or a hydrophilic organic solvent-dispersible colloid such as alcohol is used. The blending amount of the silica fine particles is preferably set to 0.1 to 30% by mass with respect to the total solid content in the coating composition when applied to the substrate 2.

  The light-absorbing material 4 uses any light-absorbing agent according to the application of the antireflection substrate 1, and for example, at least one selected from pigments such as organic pigments, inorganic pigments, and dyes that do not dissolve in solvents. including. These pigments and dyes include monoazo pigment, quinacridone, iron oxide yellow, disazo pigment, phthalocyanine green, phthalocyanine blue, cyanine blue, flavanthrone yellow, dianthraquinolyl red, indanthrone blue, thioindigo. Bordeaux, Perinone Orange, Perylene Scarlet, Perylene Red 178, Perylene Maroon, Diquiosadine Violet, Isoindolinone Yellow, Quinophthalone Yellow, Isoindoline Yellow, Nickel Nitroso Yellow, Madder Lake, Copper Azomethine Yellow, Aniline Black, Alkaline Blue, Zinc Hana, titanium oxide, petal, chromium oxide, tin oxide, iron black, titanium yellow, cobalt blue, cerulean blue, cobalt green, alumina white Viridian, Cadmium Yellow, Cadmium Red, Vermilion, Lithbon, Yellow Lead, Molybdate Orange, Zinc Chromate, Calcium Sulfate, Barium Sulfate, Calcium Carbonate, Lead White, Ultramarine, Manganese Violet, Cobalt Violet, Emerald Green, Bitumen, Carbon Black , Metal powder, azo dye, anthraquinone dye, indigoid dye, phthalocyanine dye, carbonium dye, quinoneimine dye, methine dye, quinoline dye, nitro dye, nitroso dye, benzoquinone dye, naphthoquinone dye, naphthalimide dye, or verinone dye It is done.

  The addition amount of the light absorbing material 4 is appropriately adjusted according to the absorption spectrum dependent on each material and the absorption intensity depending on the absorption coefficient, but the extinction coefficient during film formation is preferably in the range of 0 to 1.0. Is added in a range of 0.01 to 0.5. As the matrix forming material 6, for example, methyl silicate or the like is used.

  In the formation process of the low refractive index layer 5, the coating composition 7 containing the low refractive index material 3, the light absorbing material 4 and the matrix forming material 6 is prepared, and further, an appropriate solvent is added. Is applied onto the substrate 2. Examples of coating methods include brush coating, spray coating, dipping (dipping, dip coating), roll coating, flow coating, curtain coating, knife coating, spin coating, table coating, sheet coating, single wafer coating, die coating or bar coating. As long as a uniform film having a predetermined thickness can be formed on the substrate 2, any coating method is used without being limited to the above-described method.

  As a method of forming the concentration of the light absorbing material 4 so as to gradually increase toward the substrate 2 side, a material having a specific gravity higher than that of the matrix forming material 6 is used as the light absorbing material 4 to form the matrix of the light absorbing material 4. A method is used in which the concentration of the light-absorbing material 4 is increased on the substrate 2 side by being deposited in the lower part of the material 6. According to this method, two layers of a substantial light absorption layer and a low refractive index layer can be formed on the substrate 2 in one step. Therefore, the process of forming the light absorption layer separately is unnecessary, the productivity is good, and the manufacturing cost can be reduced. Moreover, since the part by the side of the base material 2 of the manufactured low reflectance layer 5 functions as a substantial light absorption layer, the antireflection base material 1 which has the reflectance characteristic in which the V curve was suppressed is obtained.

  Further, when the low refractive index layer 5 is formed so that the concentration of the light absorbing material 4 gradually increases toward the base material 2 side, while the base material 2 side functions as a substantial light absorption layer, Since it is formed integrally, it is difficult to separate, and the durability is excellent as compared with the case where the low refractive index layer and the light absorption layer are formed in separate steps. In addition to this method, for example, in the manufacturing process of the antireflection substrate 1, the light absorbing material 4 is first used in the drying process using a solvent whose solubility is different from that of the light absorbing material 4 and the matrix forming material 6. You may use the method of setting it as the solvent composition which precipitates.

  Next, an antireflection substrate according to a second embodiment of the present invention will be described with reference to FIG. In the antireflection substrate 1 of the present embodiment, a hard coat layer 8 containing a material that is substantially the same as or higher in refractive index than the substrate 2 is formed between the substrate 2 and the low refractive index layer 5. This is different from the first embodiment. The hard coat layer 8 refers to a material having a hardness of H or higher in a pencil hardness test shown in JIS 5600-5-4: 1999.

  As the material of the hard coat layer 8, a monomer or an oligomer that generates a polymerization reaction directly upon receiving irradiation of ionizing radiation such as acrylic resin, visible light, ultraviolet light, or electron beam, or under the action of an initiator, is appropriately used. A monomer or oligomer having an acrylic group or a methacryl group is preferred. In addition, a multifunctional binder component may be used to increase the scratch resistance and hardness by crosslinking. The ionizing radiation curable resin composition used for forming the hard coat layer 8 preferably has an acrylate functional group, for example, a relatively low molecular weight polyester resin, polyether resin, acrylic resin, epoxy resin, Di (meth) acrylates such as urethane resin, alkyd resin, spiroacetal resin, polybutadiene resin, polythiol polyether resin, polyhydric alcohol, ethylene glycol di (meth) acrylate, pentaerythritol di (meth) acrylate monostearate; trimethylol Tri (meth) acrylates such as propane tri (meth) acrylate and pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate derivatives and dipentaerythritol penta (meth) acrylate There are rate polyfunctional (meth) oligomers monomers and epoxy acrylate or urethane acrylate polyfunctional compounds such as acrylates such as. In the ionizing radiation curable resin composition, the photopolymerization initiator is appropriately selected from those described above. The hard coat layer 8 is formed so that the film thickness after curing is 0.1 to 100 μm, preferably 0.8 to 20 μm. When the film thickness is 0.1 μm or less, sufficient hard coat performance cannot be obtained, and when the film thickness is 100 μm or more, the film easily breaks against an impact from the outside.

  By providing the hard coat layer 8, the adhesiveness of the low refractive index layer 5 including the light absorbing material 4 is improved, and the durability of the antireflection substrate 1 can be improved. Moreover, the higher antireflection effect is acquired by adjusting the film thickness of the hard-coat layer 8 suitably.

Specific examples of the present invention will be described below in comparison with comparative examples. In the following description, “parts” all represent “parts by weight” and “%” all represent “% by weight”. Moreover, Example 1 and Comparative Examples 1 and 2 showed what contains a hard-coat layer.
(Example 1)
A coating composition (A) for forming the low refractive index layer 5 was prepared. 5.6 parts of methyl silicate MS51 (manufactured by Mitsubishi Chemical) as a matrix forming material 6 is added to 426.1 parts of methanol, and hollow silica fine particles / isopropyl alcohol (IPA) dispersion sol (solid content 20) is added as a low refractive index material 3. %: 55.5 parts of catalyst conversion), 47.4 parts of tin oxide antimony sol (solid content 30%: manufactured by catalyst conversion) as light absorbing material 4, and 50% of 0.1N nitric acid aqueous solution as an acid catalyst. Add 0 parts and mix well. This mixed solution is allowed to stand in a constant temperature atmosphere at 25 ° C. for 24 hours to obtain a silicone resin having a weight average molecular weight of 1800 and a solid content of 5.0% as a silicone resin, and then the total solid content is 3%. This was diluted with IPA to obtain a coating composition (A).

  As the substrate 2, a substrate film having a refractive index of 1.65 was used. On this base material 2, a coating material (B) containing an acrylic resin having a refractive index of 1.69 and a solid content of 25% was applied using a wire bar coater # 10 and subjected to dry explosion at 100 ° C. for 5 minutes. Then, the hard coat layer 8 was formed by irradiation with ultraviolet rays (intensity 500 mJ / cm). The film thickness of the hard coat layer 8 was 1250 nm.

  The surface of the formed hard coat layer 8 is subjected to corona treatment with an intensity of 0.7 kW, and then the coating composition (A) is applied to the surface using a wire bar coater # 4 and dried at 100 ° C. for 5 minutes. Thus, the low refractive index layer 5 was formed, and this was used as the antireflection substrate 1 of Example 1. The low refractive index layer 5 has a refractive index of 1.33 and a film thickness of 100 nm.

The specific gravity of the hollow silica fine particles is 1.68, the specific gravity of methyl silicate which is the matrix forming material 6 is 2.4, and the specific gravity of the tin oxide antimony sol which is the light absorbing material 4 is 6.6. Therefore, in the process of forming the low refractive index layer 5 after the coating composition 7 is applied, the tin oxide antimony sol having a specific gravity higher than that of methyl silicate is deposited near the hard coat layer 8. As a result, the concentration of the tin oxide antimony sol is formed so as to gradually increase toward the substrate 2 side.
(Comparative Example 1)
Comparative Example 1 is different from Example 1 in that the low refractive index layer does not contain a light absorbing material. In order to produce Comparative Example 1, first, a coating composition (C) for forming a low refractive index layer was prepared. Methyl silicate MS51 (manufactured by Mitsubishi Chemical) "31.46 parts as a matrix forming material was added to 432.04 parts of methanol, and hollow silica fine particles / isopropyl alcohol (IPA) dispersion sol (solid content 20%: as a low refractive index material) 55.5 parts of Catalytic Chemical) was added, and 50.0 parts of 0.1N nitric acid aqueous solution was added thereto as an acid catalyst and mixed well. This mixed solution is allowed to stand in a constant temperature atmosphere at 25 ° C. for 24 hours to obtain a silicone resin having a weight average molecular weight of 1800 and a solid content of 5.0% as a silicone resin, and then the total solid content is 3%. This was diluted with IPA to obtain a coating composition (C).

A coating material (B) having a refractive index of 1.69 and a solid content of 25% is applied to the base material 2 made of the same material as in Example 1 by the same method as in Example 1, and a hard coat layer having a thickness of 1250 nm is applied. Formed. On the hard coat layer, the coating composition (C) was applied in the same manner as in Example 1 and dried at 100 ° C. for 5 minutes to form a low refractive index layer. The antireflection base material was used. The low refractive index layer had a refractive index of 1.37 and a film thickness of 100 nm.
(Comparative Example 2)
Comparative Example 2 is different from Example 1 in that the light absorption layer is formed in a separate process from the low refractive index layer, and the light absorption layer and the low refractive index layer are separated. In order to produce the comparative example 2, first, the coating material (D) for forming a light absorption layer was adjusted. In this coating material (D), 3.0% of black nanoparticles “carbon black # 2650 (manufactured by Mitsubishi Chemical)” is added to the coating material (B) for forming a hard coat layer in Example 1 and Comparative Example 1. Was prepared by

A coating material (B) having a refractive index of 1.69 and a solid content of 25% was applied on the base material 2 made of the same material as in Example 1 by the same method as in Example 1 to form a hard coat layer. The surface of the hard coat layer is corona-treated with an intensity of 0.7 kW, and then the coating composition (D) is applied to the surface using a wire bar coater # 4 and dried at 100 ° C. for 5 minutes to produce light. An absorbent layer was formed. The film thickness of the light absorption layer was 100 nm. Further, the coating composition (C) was applied on the light absorbing layer by the same method as in Example 1, and dried at 100 ° C. for 5 minutes to form a low refractive index layer. The antireflection substrate of Example 2 was obtained.
(Evaluation)
The reflectance characteristics of the antireflection substrates of Example 1 and Comparative Examples 1 and 2 were evaluated. As an optical characteristic, a haze value and a total light transmittance are measured using a haze meter (“NDH2000” manufactured by Nippon Denshoku Industries Co., Ltd.), and a wavelength of 550 nm is measured using a spectrophotometer (“U-4100” manufactured by Hitachi, Ltd.). The reflectance was measured. As the difference in reflectance, a difference R ₃₈₀ between the minimum reflectance and the reflectance with respect to light having a wavelength of 380 nm, and a difference R ₇₈₀ between the minimum reflectance and the reflectance with respect to light having a wavelength of 780 nm were measured. The luminous reflectance was calculated by measuring the spectral regular reflectance at 5 ° and multiplying this measured value by the luminous coefficient. These results are shown in Table 1.

実施例１、比較例１，２のいずれにおいても、最小反射率は１．０％以下、全光線透過率は９０％以上であり、反射防止基材として好適な結果であった。しかし、光吸収層を有していない比較例１は、視感反射率が０．５％以上あり、十分な低反射化が実現されていなかった。これに対して、低屈折率層に光吸収層を含む実施例は、視感反射率が０．４％以下であり、反射防止基材として十分な低反射化が実現された。

In both Example 1 and Comparative Examples 1 and 2, the minimum reflectance was 1.0% or less, and the total light transmittance was 90% or more, which was a suitable result as an antireflection substrate. However, Comparative Example 1 which does not have a light absorption layer has a luminous reflectance of 0.5% or more, and a sufficiently low reflection has not been realized. On the other hand, the example in which the light absorbing layer is included in the low refractive index layer has a luminous reflectance of 0.4% or less, and a sufficiently low reflection is realized as an antireflection substrate.

The minimum reflectance and the reflectance difference R ₃₈₀ for light having a wavelength of 380 nm, and the minimum reflectance and the reflectance difference R ₇₈₀ for light having a wavelength of 780 nm strongly affect the reflectance characteristics in appearance. When these values are increased, the spectral reflectance curve becomes a V curve, and the color of the reflected light becomes unnatural. In an antireflection substrate, these values are generally 3.0 or less, preferably 2.0 or less. In Comparative Examples 1 and 2, the reflectance differences R ₃₈₀ and R ₇₈₀ were 2.0 or more. In particular, Comparative Example 1 had a reflectance difference R ₃₈₀ of 3.0 or more, and had reflectance characteristics in which a V curve appeared remarkably. On the other hand, in Example 1, both the reflectance difference R ₃₈₀ and the reflectance difference R ₇₈₀ were 2.0 or less, and had reflectance characteristics in which the V curve was suppressed.

In Comparative Example 2, the reflectance difference R ₃₈₀ is 3.0 or less, and the V curve is suppressed as compared with Comparative Example 1. However, since the comparative example 2 requires a step of forming the light absorption layer separately in addition to the step of forming the low refractive index layer and the hard coat layer, the productivity is poor and the manufacturing cost may be increased. On the other hand, in Example 1, by forming the low refractive index layer 5 containing the light absorbing material, there is no need to individually form the light absorbing layer, so the productivity is good and the manufacturing cost is low. can do.

  In addition, in Example 1, although the structure containing the hard-coat layer 8 was shown, the low-refractive-index layer 5 containing the light absorption material 4 was directly formed on the base material 2 without providing the hard-coat layer 8. Also in the antireflection substrate 1, as in the first embodiment, a reflectance characteristic in which the V curve is suppressed can be obtained. This can be understood from the fact that the suppression effect of the V curve is realized by the light absorbing material 4 and the presence or absence of the hard coat layer 8 does not directly affect.

1 is a side sectional view of an antireflection substrate according to a first embodiment of the present invention. The side sectional view of the antireflection substrate concerning a 2nd embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antireflection base material 2 Base material 3 Low refractive index material 4 Light absorption material 5 Low refractive index layer 6 Matrix formation material 7 Coating composition 8 Hard-coat layer

Claims (4)

In the antireflection base material provided with a low refractive index layer containing a low refractive index material having a lower refractive index than the base material on the base material,
The low-refractive index layer includes a light-absorbing material, and is formed so that the concentration of the light-absorbing material gradually increases toward the substrate side.   2. The antireflection group according to claim 1, further comprising a hard coat layer containing a material that is substantially the same as or higher in refractive index than the base material between the base material and the low refractive index layer. Wood.   The antireflective substrate according to claim 1 or 2, wherein the low refractive index material is hollow silica fine particles. A method for producing an antireflection substrate comprising a low refractive index layer containing a low refractive index material having a refractive index lower than that of the substrate on the substrate,
Applying a coating composition containing the low refractive index material, a matrix forming material in which the low refractive index material is dispersed, and a light-absorbing material having a specific gravity higher than that of the matrix forming material onto the substrate. A manufacturing method of an antireflection substrate characterized by including.

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