JPH0798401A - Antireflection film and antireflection member - Google Patents

Abstract

PURPOSE:To exhibit an excellent antireflection with a small number of superposition to light having a wavelength region and to improve mass productivity, contamination resistance and a property to sustain an antireflection effect by having a specific fluorine-contg. layer on an incident side surface. CONSTITUTION:This antireflection film has the fluorine-contg. layer 1 which has a fine rugged surface formed by many of peaks or valleys of a height or depth of 40 to 200nm and the max. horizontal length of <=200nm and has a refractive index of <=1.40 on at least its incident side surface. A graded refractive index layer and a reflected light scattering surface are formed on the surface and the antireflection film having low reflectivity is obtd. at a high degree if the antireflection film is formed in such a manner. The antireflection film exhibiting the antireflection effect satisfactory to light having the wavelength region is obtd. as well even by fewer superposed structures advantageous to mass production to the extent of superposing the film on the dispersion layer 2 of spherical particles 21 for forming the fine rugged surface of the fluorine-contg. layer 1. For example, average transmittance of usually >=98% is attained in a visible light region of 400 to 700nm wavelength with such superposed structures.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antireflection film which is excellent in mass productivity and stain resistance and is suitable for preventing reflection of light having a wavelength range in various visual recognition devices, and an antireflection member thereof.

[0002]

2. Description of the Related Art Conventionally, as an antireflection film for light having a wavelength range such as visible light, there has been known a multilayer film in which transparent thin films such as metal oxides are superposed. Such a multilayer structure can effectively prevent reflection of light having a single wavelength with a single-layer film, but cannot effectively prevent reflection of light having a wavelength range. It is effective in preventing reflection in the area. Therefore, for example, wavelength 4
In order to prevent reflection in the visible light region of 00 to 700 nm, it is general that the incident side surface is made up of three or more superposed layers formed of metal oxide layers such as SiO ₂ , and in the case of two layers, it is high. It has been said that accurate antireflection cannot be achieved.

However, in order to form an antireflection film having a multi-layered structure, an advanced technique is required to control the film thickness of the thin films with high precision in consideration of the refractive index of each thin film to be superposed, and therefore the number of superposed films is increased by one layer. This alone requires a lot of time and labor, and there is a problem that the manufacturing efficiency is greatly reduced. Further, there is a problem that the metal oxide layer on the incident side surface is easily contaminated with fingerprints or the like, and the antireflection effect is significantly reduced due to the contamination.

[0004]

DISCLOSURE OF THE INVENTION The present invention shows an excellent antireflection effect even with light having a wavelength range with a small number of superpositions, is excellent in mass productivity, and is also excellent in stain resistance and antireflection effect. An object of the present invention is to obtain an antireflection film and an antireflection member having excellent durability.

[0005]

According to the present invention, the incident side surface has a height or depth of 40 to 200 nm and a maximum horizontal length of 2 nm.
An antireflection film having a fluorine-containing layer having a fine uneven surface formed of a large number of peaks or valleys of 00 nm or less and a refractive index of 1.40 or less, and the antireflection film of a transparent substrate. An antireflection member having at least one side is provided.

[0006]

By using the fluorine-containing layer having the fine uneven surface having the above-mentioned structure as the incident side surface, an inclined refractive index layer and a reflected light scattering surface are formed on the surface to obtain an antireflection film having a highly low reflectance. . And a satisfactory antireflection effect with respect to light having a wavelength range is exhibited even with a small overlapping structure that is advantageous in mass productivity and is overlapped with a dispersion layer of spherical fine particles for forming the fine uneven surface of the fluorine-containing layer. It can be an antireflection film. By the way, the overlapping structure has a wavelength of 400
Average transmittances of 98% or more can be achieved in the visible light range of up to 700 nm. Further, by having a fluorine-containing layer on the incident side surface, it is excellent in water repellency, oil repellency, etc., and is unlikely to be contaminated. In addition, the contamination is easily removed and excellent in contamination resistance,
The antireflection effect can be maintained for a long period of time.

[0007]

EXAMPLES The antireflection film of the present invention has a height or depth of 40.
-200 nm, the maximum horizontal length is 200 nm or less, and the refractive index is 1.40 having a fine uneven surface formed of a large number of peaks or valleys.
It has at least the following fluorine-containing layer on the incident side surface. An example thereof is shown in FIG. 1 is a fluorine-containing layer. Reference numeral 2 is a dispersion layer, and 21 is its spherical fine particles, which are for forming the fine uneven surface of the fluorine-containing layer.

In the present invention, the fluorine-containing layer may form the antireflection film as a single layer, or the antireflection film may be formed as a superimposition with another layer for the purpose of preventing reflection of light having a wavelength range. In some cases, it is provided as a layer forming the incident side surface of the antireflection film as described above.

Therefore, the thickness of the fluorine-containing layer is appropriately determined according to the intended layer structure of the antireflection film, but generally in the case of using a single antireflection film from the viewpoint of achieving low reflectance. , 5 to 200 nm, especially 1 of the wavelength of the target antireflection light
In the case of an antireflection film having a thickness of / 4 and a two-layer superposition structure,
The optical film thickness is 0.1 to 0.6 times the central wavelength in that wavelength range. The optical film thickness is defined as the product of the refractive index and the thickness.

The formation of the fluorine-containing layer has a refractive index of 1.40.
It can be carried out using the following fluorine-containing compound. When the refractive index exceeds 1.40, it is difficult to achieve the target low reflectance. A fluorine-containing compound that can be preferably used has a refractive index of 1.36 or less and is 100 μm.
When the thickness is m, the transmittance is 80% or more and the content of fluorine atoms is 60% by weight or more.

Examples of fluorine-containing compounds that can be preferably used include the following. General formula (1): (However, R is a fluorine atom, a hydrogen atom or a monovalent hydrocarbon group, and n is 1 to 40.), and the fluorine-containing compound has a fluorine atom content of 60% by weight or more.

Formula (a): A fluorine-containing compound having a refractive index of 1.38 represented by

In the above-mentioned general formula (1), a fluorine-containing compound in which all R are fluorine atoms can be particularly preferably used in the present invention. By the way, if all of R are fluorine atoms and n is 9.6 on average, the refractive index is 1.
34 and is soluble in a solvent such as a perfluoro solvent represented by the following general formula (2).

General formula (2): (However, n is 2 to 8.)

Further, the fluorine-containing compound represented by the above formula (a) is also soluble in tetrahydrofuran or the like, and in the present invention, the fluorine-containing compound soluble in the solvent is used in a coating method such as a dipping method or a spin coating method. A thin film can be easily formed, which is preferable in terms of mass productivity. In that case, the solution concentration is usually 0.01 to 20% by weight from the viewpoint of film thickness control and the like, but is not limited to this.

The formation of a fluorine-containing layer having a fine uneven surface having a height or depth of 40 to 200 nm, a maximum horizontal length of 200 nm or less, and in particular, a large number of peaks or valleys of 40 to 200 nm is, for example, a buff. Method, corona discharge method, ion etching method, or other suitable surface roughening method, and in particular, microfabrication surface roughening method may be used. Alternatively, the roughened surface may be reflected in the fluorine-containing layer. In that case, examples of the lower layer such as the layer directly below the surface to be roughened include an internal layer of a superposed layer forming an antireflection film, a base material for attaching the antireflection film, and the like.

A preferred method in which the surface of the fluorine-containing layer is made into a finely roughened surface by roughening the surface of the lower layer, especially the layer immediately below, has an average particle diameter of 200 nm or less as illustrated in FIG. In particular, it is a method of forming a dispersion layer 2 of spherical fine particles 21 of 40 to 200 nm and finely roughening the surface of the fluorine-containing layer 1 based on the dispersion layer 2 (JP-A-3-15).
0501 publication). According to such a method, it is possible to easily form a fluorine-containing layer thinner than the particle diameter of the spherical fine particles by a coating method such as a dipping method or a spray method, and to form a composite or superposed layer of the spherical fine particles and the fluorine-containing layer. A target fine uneven surface can be obtained. The spherical fine particles are preferably fixed in a dispersed state with an appropriate binder made of ethyl silicate, polymer or the like.

As the spherical fine particles, various fine particles made of an inorganic substance such as ceramics and an organic substance such as plastics can be used. Fine particles that can be preferably used are
It is hard and spherical as much as possible, and has excellent transparency when dispersed in a transparent film. Examples are silica,
Examples of the fine particles include alumina, titania, zirconia and the like.

In the present invention, the fine uneven surface of the fluorine-containing layer has a height or depth of 40 to 200 nm and a maximum horizontal length of 2.
When it is not formed of a large number of peaks or troughs of 00 nm or less, the antireflection film has poor optical properties such as low reflectance and scratch resistance. The preferred fine uneven surface is such that the peaks or valleys are 60% or more based on the plane area, especially 65 to 95%.
Occupies and distributes as evenly as possible.

In the antireflection film of the present invention, Si
A publicly known layer composed of a metal oxide such as O ₂ , ZrO ₂ , Al ₂ O ₃ or Y ₂ O ₃ and magnesium fluoride may be superposed to improve the transmittance as an antireflection film having two or more layers. You can also measure. In that case, the layers other than the fluorine-containing layer can be appropriately formed according to the conventional method according to the refractive index, the number of overlapping layers, and the like, and the formation is performed by, for example, a vacuum vapor deposition method,
It can be performed by an appropriate method such as a vapor deposition method such as a sputtering method or an ion plating method.

The antireflection film of the present invention can be applied by forming a predetermined layer on the surface intended for antireflection, or by providing an antireflection film on a base material such as a film. It can also be applied by a method of forming a member and attaching it to a surface for the purpose of antireflection.
The method applied as an antireflection member has an advantage that it can be easily attached to an existing article such as a display device or attached to a curved surface or a large area surface.

The antireflection member of the present invention has the antireflection film of the present invention on at least one side of the transparent substrate.
An example thereof is shown in FIG. 3 is a transparent substrate. In addition, 4 is an adhesive layer provided as needed.

As the transparent base material, an appropriate material can be used.
Those having excellent transmittance and strength are preferable. Generally, a plate, a film or a sheet made of glass, a plastic such as polyester or triacetyl cellulose is used. Further, optical functional materials such as a polarizing plate and a retardation plate can be used. The thickness can be appropriately determined and is generally 5 mm or less, but the thickness is not limited to this.

Further, a transparent substrate which has been subjected to an appropriate treatment such as a hard coat treatment may be used. The hard coat treatment is intended to reinforce the substrate, especially the surface thereof, and is generally formed of a thermosetting resin such as a silicone resin. Further, it may be a hard coat layer mixed with oxide fine particles such as silica, alumina, titania and zirconia, and conductive fine particles such as tin oxide, indium oxide and antimony oxide. A transparent substrate can be used. The antireflection member can be formed by a method of providing an antireflection film on one side or both sides of the transparent substrate.

The antireflection member of the present invention may be provided with an adhesive layer for the purpose of adhering to an application target. The adhesive layer to be provided preferably has a refractive index difference of ± 5% or less of the transparent substrate from the viewpoint of preventing reduction of transmittance. For forming the adhesive layer, an appropriate adhesive such as an acrylic adhesive, a rubber adhesive, a silicone adhesive or a hot melt adhesive can be used. Those having excellent transparency and weather resistance are preferable. The attachment of the adhesive layer may be performed by an appropriate method such as a coating method or a transfer method of the one provided on the separator. When the adhesive layer is a pressure-sensitive adhesive layer, it is preferable to protect the surface with a separator or the like until practical use.

The antireflection film or the antireflection member of the present invention is preferably used for preventing interfacial reflection of various articles such as optical functional materials such as polarizing plates, display devices such as liquid crystal display devices, instruments such as weighing scales. You can

Example 1 A glass plate having a thickness of 500 μm (refractive index 1.53) was immersed in a dispersion liquid of ethyl silicate in a monodisperse ethanol solution of silica having an average particle diameter of 150 nm, and the glass plate was immersed at 30 ° C. at 160 ° C.
A minute uneven surface (silica concentration 4% by weight) is formed by firing for a minute, and then in the general formula (1) above, all of R are fluorine atoms and n is an average of 9.6 perfluorinated compounds of a fluorine-containing compound. A dip coat was applied by dipping in a 0.05 wt% solution with a solvent to form a 10-nm-thick fluorine-containing layer, to obtain an antireflection member. The fluorine-containing layer has a height or depth of 50 to 70 nm and a maximum horizontal length of 14
It had a fine concavo-convex surface composed of many peaks or valleys of 0 to 150 nm. The film thickness was measured by observing a cross section with an electron microscope, and the perfluoro solvent represented by the general formula (2) was used (the same applies hereinafter).

Example 2 An antireflection member was obtained in the same manner as in Example 1 except that a liquid in which silica having an average particle diameter of 120 nm was dispersed was used. The fluorine-containing layer has a thickness of 10 nm and a height or depth of 40 to 6
At 0 nm, it had a fine concavo-convex surface composed of a large number of peaks or valleys having a maximum horizontal length of 110 to 120 nm.

Example 3 A triacetyl cellulose film (refractive index 1.49) having a thickness of 500 μm was used in place of the glass plate, and the temperature was 3 ° C. at 80 ° C.
An antireflection member was obtained in the same manner as in Example 1 except that silica was dispersed and fixed by baking treatment for a period of time.

Example 4 A triacetyl cellulose film (refractive index 1.49) having a thickness of 500 μm was used in place of the glass plate, and the temperature was 3 ° C. at 80 ° C.
An antireflection member was obtained in the same manner as in Example 2 except that silica was dispersed and fixed by baking treatment for a period of time.

Comparative Example 1 A glass plate on which silica was dispersed and fixed according to Example 1 was used as it was as an antireflection member except that no fluorine-containing layer was provided.

Comparative Example 2 A glass plate having silica dispersed and fixed according to Example 2 was used as it was as an antireflection member except that a fluorine-containing layer was not provided.

Comparative Example 3 A triacetyl cellulose film having silica dispersed and fixed according to Example 3 was directly used as an antireflection member except that a fluorine-containing layer was not provided.

Comparative Example 4 A triacetyl cellulose film having silica dispersed and fixed according to Example 4 was used as it was as an antireflection member except that a fluorine-containing layer was not provided.

Comparative Example 5 On one side of a 500 μm thick triacetyl cellulose film (refractive index 1.49), a Z layer having a thickness of 125 nm was formed by vapor deposition.
rO ₂ (refractive index 2.05) was formed, and a fluorine-containing layer having a thickness of 95 nm was superposed thereon in accordance with Example 1 to obtain an antireflection member. The vapor deposition was performed by an electron gun method without heating the vapor deposition surface under the conditions of an ultimate vacuum of 5 × 1/10 ⁵ Torr and a vapor deposition rate of about 0.5 nm / sec (the same applies hereinafter).

Comparative Example 6 A Y ₂ O ₃ layer having a thickness of 130 nm (refractive index 1.8) was formed on one surface of a glass plate having a thickness of 500 μm (refractive index 1.53) by vapor deposition.
7) and 85 nm thick SiO ₂ (refractive index 1.46) were superposed to obtain an antireflection member.

Comparative Example 7 A glass plate (refractive index: 1.53) having a thickness of 500 μm was formed on one surface thereof with ZrO ₂ having a thickness of 120 nm (refractive index: 2.0).
5) and 90 nm thick SiO ₂ (refractive index 1.46) were superposed to obtain an antireflection member.

Evaluation Test Before Contamination Light having a wavelength of 400 to 700 nm is vertically incident from the antireflection film side of the antireflection members obtained in Examples and Comparative Examples, and the reflectance and the transmittance are measured with a spectrophotometer. The average reflectance and the average transmittance in the visible range were obtained.

After contamination, an acrylic pressure-sensitive adhesive tape was pressure-bonded onto the antireflection film and rubbed with an eraser 10 times, and then the adhesive tape was vigorously peeled off in the vertical direction. The average transmittance was determined.

The above results are shown in Table 1.

[Table 1]

From Table 1, the antireflection films of the examples show excellent antireflection effect against light in the visible region and practically satisfactory transmittance, and at the same time, they are hard to be contaminated and have antireflection effect,
It can be seen that the durability of the transmittance is excellent.

[0042]

INDUSTRIAL APPLICABILITY The antireflection film of the present invention has an excellent antireflection effect, and even in the case of a superposed layer composed of two layers, it exhibits an excellent antireflection effect with respect to light having a wavelength range, and is practical and mass-produced. It has excellent properties. Further, it has a fluorine-containing layer on the incident side surface and is less likely to be contaminated, and the contamination is easily removed, and the contamination resistance is excellent and the antireflection effect is durable.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of an antireflection film.

FIG. 2 is a sectional view of an example of an antireflection member.

[Explanation of symbols]

 1: Fluorine-containing layer 2: Dispersion layer of spherical fine particles 21: Spherical fine particles 3: Transparent base material 4: Adhesive layer

Claims (5)

[Claims] 1. The height or depth of the incident side surface is 40 to 2
An antireflection film having a fluorine-containing layer having a refractive index of 1.40 or less, which has a fine uneven surface formed of a large number of peaks or troughs having a maximum horizontal length of 200 nm or less at 00 nm. 2. The fluorine-containing layer has the general formula: (Wherein R is a fluorine atom, a hydrogen atom or a monovalent hydrocarbon group, and n is 1 to 40) and is formed of a fluorine-containing compound having a refractive index of 1.36 or less, which is soluble in a solvent. The antireflection film according to claim 1. 3. An average particle size of 200 directly below the fluorine-containing layer.
The antireflection film according to claim 1, which has a dispersion layer of spherical fine particles having a size of not more than nm, and on which a fine uneven surface of the fluorine-containing layer is formed. 4. An antireflection member having the antireflection film according to claim 1 on at least one side of a transparent substrate. 5. The antireflection member according to claim 4, wherein the antireflection member has an adhesive layer having a refractive index difference of ± 5% or less of that of the transparent substrate.