JP2006317957A - Antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film used for a various kinds of displays, by which required visual information can be clearly read by preventing reflection of light at a surface and in which color development due to interference of light is suppressed and the whole film has low reflection by lessening an optical thin film layer. <P>SOLUTION: On a transparent rugged base material 2 having a rugged shape 6 on its surface, only a single layer of the optical thin film layer 5 having lower refractive index than that of the base material and film thickness of λ/4n (wherein (n) is refractive index and λ is 500 to 600nm) is provided to form a laminated film. Haze value of the whole laminated film is 40% or less and difference between minimum spectral reflectance and highest spectral reflectance in a visible light region (380 to 780nm) is 0.5% or less. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

TECHNICAL FIELD OF THE INVENTION

  The present invention relates to a film having an antiglare optical function, and in particular, various displays such as word processors, computers, and televisions, the surface of a polarizing plate used in a liquid crystal display device, a lens made of transparent plastic, a lens for sunglasses, and glasses with a degree. It belongs to a film excellent in optical properties suitable for an anti-reflection film on the surface of a window glass of an optical lens, a lens of a camera finder, a cover of various instruments, an automobile, a train, etc.

Conventional technology

  Transparent substrates such as glass and plastic are used for displays such as curved mirrors, rearview mirrors, goggles, window glass, personal computers, word processors, and various other commercial displays. And when observing visual information such as objects, characters, figures, etc. through these transparent substrates, or images from mirrors from the reflective layer through the transparent substrates, the surface of these transparent substrates reflects the light, There was a problem that visual information was difficult to read.

Conventionally, technologies for preventing the reflection of light include a method of applying an antireflection coating on the surface of a substrate such as glass or plastic, and MgF ₂ having a thickness of about 0.1 μm on the surface of a transparent substrate such as glass. A method of providing an ultra-thin film or a metal vapor-deposited film, a method of coating an ionizing radiation curable resin on the surface of a plastic lens and the like, and further forming a SiOx or MgF ₂ film on the surface by vapor deposition. There was a method of forming a coating film having a lower refractive index on the cured film.

  Moreover, the optical thin film layer was provided in the surface of the base material in multiple layers, and the spectral minimum reflectance of the film has been lowered by utilizing the light interference effect. However, a multilayer optical thin film is required to have a management accuracy of each thickness. That is, in the case of an optical thin film layer having a large number of layer structures, an antireflection effect can be obtained, but it is difficult to uniformize a color that develops due to light interference. Further, in the case of an optical thin film having a small layer structure, there is a problem that a sufficient antireflection effect cannot be obtained. In particular, it has been one of the important issues in antireflection films such as liquid crystal displays.

  Furthermore, when the spectral minimum reflectance is locally reduced in a specific wavelength region due to optical interference, there is a problem that the numerical value of the spectral reflectance in other wavelength regions inevitably increases. Further, in order to provide a sufficient antireflection effect, a wavelength region with high reflectivity has been made as much as possible by forming a multilayer optical thin film layer. However, providing an optical thin film layer in multiple layers has a problem that it is unstable in process.

  In the present invention, when the visual information such as objects, characters, and figures to be identified through a transparent substrate used for various displays or an image from a mirror is observed from a reflective layer through the transparent substrate, the surface of the transparent substrate is made of light. An object of the present invention is to provide an antireflection film that prevents reflection and transmits necessary visual information inside and can be clearly read. The object of the present invention is to provide an antireflection film that reduces the optical interference by reducing the number of optical thin film layers and is low in the wavelength range where the reflectance is high and the film as a whole has low reflection.

  In order to solve the above-mentioned problems, the present invention provides an optical thin film layer that is transparent and has a concavo-convex shape on the surface, with an optical thin film layer lower than the refractive index of the substrate λ / 4n (where n: A laminated film provided with only a single layer with a film thickness of λ: 500 to 600 nm, the haze value of the whole laminated film is 40% or less, and a visible light region (hereinafter referred to as 380 in this specification). The difference between the lowest spectral reflectance and the highest spectral reflectance in ˜780 nm) is 0.5% or less. And it is an antireflection film whose haze value of the said laminated | multilayer film whole is 20 to 40% of range. Moreover, it is an antireflection film whose surface average roughness Ra of the outermost surface of the said uneven | corrugated base material is 0.1-0.5 micrometer. And it is an antireflection film whose refractive index difference of said concavo-convex base material and an optical thin film layer is 0.03-0.15. Then, an optical thin film layer having a refractive index lower than the refractive index of the coating layer is λ / 4n (where n: refractive index, λ: 500 to 600 nm) through a coating layer having an uneven shape on a transparent substrate sheet. The haze value of the whole laminated film is 40% or less, and the difference between the lowest spectral reflectance and the highest spectral reflectance in the visible light region is 0. The antireflection film is 5% or less. Moreover, it is an antireflection film which has the haze value of the whole laminated film of Claim 5 in the range of 20 to 40%. Moreover, it is an antireflection film whose surface roughness Ra of the outermost surface of the coating layer having the uneven shape is 0.1 to 0.5 μm. And it is an antireflection film whose refractive index difference of the coating layer with the said uneven | corrugated shape and an optical thin film layer is 0.03-0.15. Furthermore, the coating layer according to claim 5 is an antireflection film having a cured film having a pencil hardness of 2H or more.

Embodiments of the Invention

  In the invention of claim 1, as shown in FIG. 1, an optical thin film layer 5 having a refractive index lower than the refractive index of the substrate is λ / 4n (provided that λ / 4n) (n: refractive index, λ: 500 to 600 nm) is a laminated film provided with only a single layer. And it is the antireflection film 1 in which the haze value of the whole laminated film is in the range of 40% or less. And it is the antireflection film 1 of the range whose haze value of the said laminated | multilayer film whole is 20 to 40%. Moreover, it is the antireflection film 1 whose surface average roughness Ra of the outermost surface of the said uneven base material 2 is 0.1-0.5 micrometer. And it is an antireflection film whose refractive index difference of said concavo-convex base material 2 and optical thin film layer 5 is 0.03-0.15. And invention of Claim 5 is a laminated film which provided the said optical thin film layer 5 through the uneven | corrugated coating layer 4 which has the uneven | corrugated shape 6 on the transparent base material sheet 3 as shown in FIG. Yes, the antireflection film 1 has a haze value of 40% or less of the entire laminated film. Moreover, it is the antireflection film 1 which has the haze value of the whole laminated film of Claim 5 in the range of 20 to 40%. Moreover, it is the antireflection film 1 whose surface roughness Ra of the outermost surface of the coating layer 4 which has the said uneven | corrugated shape is 0.1-0.5 micrometer. And it is the antireflection film 1 whose refractive index difference of the coating layer 4 with the said uneven | corrugated shape and the optical thin film layer 5 is 0.03-0.15. Moreover, the coating layer 4 of Claim 5 is the antireflection film 1 of the cured film whose pencil hardness is 2H or more.

  In the present invention, by providing the optical thin film layer as a single layer on the transparent substrate provided with the concavo-convex shape, the combination of the concavo-convex light diffusion effect and the optical interference effect of the optical thin film layer, the laminated film as a whole, Constructs an antireflection film with high total light transmittance, spectral average reflectance in the visible light region of 2% or less, and a difference between the lowest spectral reflectance and the highest spectral reflectance of 0.5% or less and no color unevenness To do.

  The uneven substrate 2 used in the invention of claim 1 is formed from a stretched or unstretched film of ceramics such as transparent glass having a refractive index of 1.5% or more, or a transparent plastic. In addition to normal optical glass, thermoplastic resins such as polyester, tri- or diacetylcellulose, polyamide, polyimide, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, methyl polymethacrylate, polycarbonate, and polyurethane are used. can do. The thickness of the film depends on the rigidity, strength, and manufacturing method of the material, but is 30 to 1000 μm for plastic films and 200 to 3000 μm for ceramics. The concave / convex shape is formed by laminating a shaping film or a shaping plate at the time of film formation, or forming a film on which film formation has been completed by a process such as sandblasting.

  The concavo-convex substrate is shaped so that the haze is 40% or less, and the surface roughness Ra of the concavo-convex shape is 0.1 to 0.5 μm. By providing a single optical thin film layer in such an uneven shape, the spectral average reflectance in the visible light region is 2.0% or less, and the minimum spectral reflectance and the maximum spectral reflectance in the visible light region are The difference can be 0.5% or less. It is preferable that the spectral reflectance is 2% or less and the maximum spectral reflectance and the minimum spectral reflectance in the visible light region are 0.5% or less. When the surface roughness Ra exceeds 0.5 μm, the surface becomes rough and is not suitable for applications such as liquid crystal displays. If the haze exceeds 40%, the entire surface becomes whitish, which is unsuitable for display applications. Further, when the surface roughness Ra is less than 0.1 μm, the light diffusing effect due to the surface irregularities becomes insufficient, and the optical thin film layer having only a single layer has a spectral average reflectance of 2.0% in the visible light region. It is difficult to make it below.

  The concavo-convex shape in the invention of claim 5 is formed on the transparent base material sheet 3 by coating for the purpose of improving the characteristics such as the surface hardness or the same as that prepared with the concavo-convex base material. And the coating material which mainly has a thermosetting type or ionizing radiation-curable composition is applied to the transparent base material sheet 3, and the uneven | corrugated coating layer 4 which has a surface characteristic different from a base material sheet is formed. . Moreover, the primer layer which strengthens the adhesion | attachment of an uneven | corrugated coating layer directly or on a base material sheet can be provided, and an uneven | corrugated coating layer can also be formed. The coating amount of the uneven coating layer (in this specification, the thickness of the coating amount is described as a solid content) is 2 to 20 μm. When the coating amount is 2 μm or less, it is not only possible to form an accurate uneven shape, but also the characteristics of the coating material cannot be exhibited. On the other hand, when the coating amount is 20 μm or more, it is a waste of resources, and it takes time for curing, and the flexibility of the coating layer is impaired, and cracks are generated in the processing step. Alternatively, the uneven coating layer can be formed by coating / molding a composition mainly composed of a thermoplastic resin.

  When the difference between the refractive index formed by the concavo-convex coating layer and the refractive index of the optical thin film layer is not 0.03, no interference effect is obtained. Due to color development. Therefore, the difference in refractive index is 0.03 to 0.15, preferably 0.05 to 0.10.

  The uneven coating layer is not only suitable for forming uneven shapes produced in small lots, but also provides surface properties of the base sheet, hardness to prevent scratches, and antifouling properties to prevent adhesion of foreign matter It is provided to do. Therefore, in addition to thermoplastic resins, use of curable resins, thermosetting resins, ionizing radiation curable resins, etc. that are easy to form unevenness with films, if necessary, with surfactants or release materials added Is preferred. For example, in addition to thermoplastic resins such as polycarbonate, polymethyl methacrylate, polymethylpentene, polyimide, and polyester, there are two-component reactive resins such as polyester / isocyanate, polyether / isocyanate, and epoxy / isocyanate. More preferably, polyester (meth) acrylate (in the present specification,..., Methac ... and aku ... are described as (meth) ac ...), epoxy (meth) acrylate. , An ionizing radiation curable resin containing polyfunctional (meth) acrylate as a main component. These resins are coated on a base sheet, and in a molten or uncured state, crimped and molded with a shaping film, and cured by cooling, heating and / or ionizing radiation to form an uneven coating layer. It constitutes. Moreover, the uneven | corrugated shape can also be formed by the sandblast process for the hardened coating layer.

The concavo-convex coating layer can be formed by applying a composition in which inorganic or organic fine particles are dispersed to the above resin varnish, in addition to formation by a shaping film. The coating composition is composed of 1 part by weight of thermosetting resin and / or ionizing radiation resin, ITO, SiO ₂ , Al ₂ O ₃ , polycarbonate, polyimide, polyamide, polyester, polymethyl. A mat material selected from one or more kinds of fine particles such as methacrylate is composed of 0.2 to 20 parts by weight.

  The optical thin film layer preferably has a refractive index smaller than that of the base sheet, and is SiOx (x is 1.5 to 4.0). SiOx is provided by vapor deposition, plasma CVD or sputtering. The raw material for SiO x is preferably organic siloxane as a raw material gas, and the film to be deposited is preferably maintained at the lowest possible temperature by plasma CVD under the condition that no other inorganic vapor deposition source is present. Including the undecomposed organosiloxane in the optical thin film layer (SiOx layer) of the present invention is effective in maintaining the flexibility and adhesiveness of SiOx. The thickness d of the optical thin film layer is preferably provided to a thickness d that satisfies λ / 4n (provided that λ is 500 to 600 nm, and n is 1.5, d is about 80 to 100 nm). There is a problem that when the thickness is less than the above value (for example, 80 nm, no interference effect is exhibited and the total light transmittance is not sufficient, and when the thickness exceeds the above value (for example, 100 nm), color is developed.

Hereinafter, the present invention will be described in more detail based on experimental examples. As shown in FIG. 1 or FIG. 2, about 7 μm of the “coating liquid composition” shown below is applied to the concavo-convex substrate 2 having a thickness of 80 μm shown in Table 1 or the triacetyl cellulose film as the substrate sheet 3. , Various shaped films are laminated and cured with UV irradiation equipment (80 W / cm × 10 m / min × 4 times), then the shaped film is peeled off, and the laminated film having the uneven coating layer 5 on the surface Was made. Next, the laminated film was saponified with an 8% aqueous solution of caustic soda at 60 ° C. for 2 minutes, washed with water and dried. Further, SiOx was deposited on the surface of the concavo-convex shape 6 of the other laminated film except for Comparative Example 5 (*) with a film thickness of λ / 4 (about 90 nm), and the haze or surface roughness of Examples and Comparative Examples of the present invention. A thick antireflection film 1 was constructed.
"Coating fluid composition"
Pentaerythritol triacrylate (functional acrylate) 100 parts by weight Photopolymerization initiator 3 parts by weight Cellulose propionate 1.25 parts by weight Silicone (leveling agent) 0.1 parts by weight

For each sample of Examples and Comparative Examples having the haze and surface roughness shown in (Table 1) of the above experiment, spectral reflectance, total light transmittance, degree of color development and gloss of the antireflection film are as follows: The results of measurement and evaluation are shown in (Table 2).
-Surface roughness: Measured with Surfcoder AY-31 manufactured by Kosaka Laboratory.
-Haze: Measured with a direct reading haze meter manufactured by Toyo Seiki Co., Ltd.
Spectral reflectance: Spectral reflectance measuring instrument manufactured by Shimadzu Corporation MPC-3100 is used to measure the total light transmittance, the highest spectral reflectance, and the lowest spectral reflectance in the visible light range, and calculate the difference. .
Gloss: Gloss meter GM-3D manufactured by Murakami Color Research Laboratory is used to evaluate the gloss at 60 degrees of incident light.
-Degree of color development: Visually evaluate the degree of color development due to light interference.
3: Large color development 2: Slight color development 1: Almost no color development

・実施例９及び１０は、反射率が比較的大きく、反射防止効が若干劣るものであった。
・比較例１はヘイーズが高く画像の鮮明性が劣るものであった。

In Examples 9 and 10, the reflectance was relatively large and the antireflection effect was slightly inferior.
Comparative Example 1 had high haze and poor image sharpness.

[The invention's effect]
As described above, the antireflection film of the present invention is optically applied to a film having an irregular shape shaped haze of 40% or less, or a curable coating layer provided with an irregular shape haze of 40% or less. The thin film layer is formed as a single layer. Therefore, the formation of a single-layer optical thin film layer is easier to manage in production as compared with a multilayered one, and in the visible light region, an antireflection film having a low reflectance with a spectral average reflectance of 2% or less is used. There is an effect that can be provided. In addition, unlike the conventional antireflection film, the difference between the highest spectral reflectance and the lowest spectral reflectance in the visible light region can be 0.5% or less, so the antireflection effect can be achieved even in the high spectral reflectance wavelength region. Will not be disturbed. And the antireflection film which provided the curable uneven | corrugated coating layer has an effect excellent in surface characteristics.

It is a section schematic diagram showing layer composition of an antireflection film of the present invention. It is a section schematic diagram showing other layer composition of the antireflection film of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antireflection film 2 Uneven base material 3 Base material sheet 4 Uneven coating layer 5 Optical thin film layer 6 Uneven shape

Claims (9)

  An optical thin film layer having a thickness of λ / 4n (where n: refractive index, λ: 500 to 600 nm) is a single layer on an uneven substrate that is transparent and has an uneven shape on the surface. The haze value of the entire laminated film is 40% or less, and the difference between the lowest spectral reflectance and the highest spectral reflectance in the visible light region (380 to 780 nm) is 0.5. % Antireflective film characterized by being less than or equal to%.   2. The antireflection film according to claim 1, wherein the entire laminated film according to claim 1 has a haze value in the range of 20 to 40%.   2. The antireflection film according to claim 1, wherein the surface average roughness Ra of the outermost surface of the concavo-convex substrate is from 0.1 to 0.5 [mu] m.   An antireflection film, wherein the refractive index difference between the uneven substrate according to claim 1 and the optical thin film layer is 0.03 to 0.15.   An optical thin film layer having a refractive index lower than the refractive index of the coating layer is formed on a transparent substrate sheet having a concavo-convex shape by a film of λ / 4n (where n: refractive index, λ: 500 to 600 nm). A laminated film having a single layer only in thickness, the haze value of the whole laminated film is 40% or less, and the difference between the lowest spectral reflectance and the highest spectral reflectance in the visible light region is 0.5% An antireflection film characterized by the following.   The haze value of the whole laminated film according to claim 5 is in the range of 20 to 40%.   6. The antireflection film according to claim 5, wherein the surface roughness Ra of the outermost surface of the multilayer film is from 0.1 to 0.5 [mu] m.   An antireflection film, wherein the difference in refractive index between the coating layer according to claim 5 and the optical thin film layer is 0.03 to 0.15.   5. The antireflection film according to claim 4, wherein the coating layer is a cured film having a pencil hardness of 2H or more.

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