JP2002243902A - Antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antireflection film not requiring a hard coat layer disposed on a conventional antireflection film, excellent in surface hardness and heat resistance and using a substrate different from a conventional polymer film having flexibility. SOLUTION: In the antireflection film with an antireflection layer on at least one face of a substrate, the substrate is based on borosilicate glass.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an antireflection film, particularly to an antireflection film for a display.

[0002]

2. Description of the Related Art Conventionally, in many places where displays are used, external light such as fluorescent lamps or sunlight is reflected, making it difficult to view the originally displayed screen. In recent years, there has been a demand for an improvement in display image quality under such an environment. In response to such a demand, an antireflection film having an antireflection effect in a wide range of visible light has been attached to the surface of a display.

As shown in FIG. 4, such an antireflection film is provided on a light-transmitting transparent substrate 1 on a hard coat layer 5, an antireflection layer 2 and, if necessary, on the antireflection film. A structure in which a water / oil repellent layer 3 for imparting water and oil repellency is sequentially formed is often used. Here, the hard coat layer 5 is formed to impart mechanical strength such as abrasion resistance of the antireflection layer.

Here, as the light-transmitting transparent substrate 1, a plastic film such as a triacetyl cellulose film, a polycarbonate film, a polyethersulfone film, a polymethyl acrylate film, a polyethylene terephthalate film or the like is used.

[0005]

However, the above plastic film for display use is expensive,
Further, since the plastic film is soft and easily scratched, the surface of the antireflection film needs to be subjected to a hard coating treatment with abrasion resistance. A separate step is required to provide the hard coat layer. Further, since the hard coat layer has only one surface and the back surface is easily damaged, a protective film may be attached. For these reasons, the production cost of the antireflection film has increased.

[0006] Further, since the plastic film as a substrate is weak to heat, there is a problem in production efficiency. In particular, when a triacetylcellulose film was used as a substrate, it was complicated to provide a hard coat layer because a saponification treatment for hydrophilizing the film surface was required.

The present invention has been made to solve the above problems, and does not require a hard coat layer provided on a conventional antireflection film, has excellent surface hardness and heat resistance, and is flexible. It is an object of the present invention to provide an antireflection film using a substrate different from a conventional polymer film having the following.

[0008]

In order to solve the above problems, the invention according to claim 1 is directed to an antireflection film having an antireflection layer on at least one surface of a base material, wherein the base material is mainly made of borosilicate glass. An antireflection film characterized as being a component.

According to a second aspect of the present invention, in the antireflection film according to the first aspect, the base material is a film-shaped base material having a thickness of 10 to 200 μm that can be wound around a cylindrical winding core. It is characterized by being.

The invention according to claim 3 is the antireflection film according to claim 1 or 2, wherein the base material is
It is characterized by containing borosilicate glass as a main component obtained by adding an inorganic oxide other than the components constituting the borosilicate glass.

[0011] The invention according to claim 4 is the invention according to claims 1 to 5.
3. The antireflection film according to any one of 3.
The antireflection layer has at least two layers made of oxides having different refractive indexes.

The invention according to claim 5 is the invention according to claims 1 to
4. The antireflection film according to any one of 4.
At least one of the layers constituting the antireflection layer,
It has a light absorbing property.

The invention according to claim 6 is the invention according to claims 1 to
5. The anti-reflection film according to any one of 5.
The refractive index of the antireflection layer is smaller than the refractive index of the substrate.

[0014] The invention according to claim 7 is the invention according to claims 1 to
6. The anti-reflection film according to any one of 6.
At least one layer having water repellency and oil repellency is formed on the uppermost layer of the antireflection layer.

The invention according to claim 8 is the antireflection film according to claim 7, wherein the water-repellent and oil-repellent layer is perfluorosilane.

The invention according to claim 9 is the first invention.
8. The antireflection film according to any one of the above items 8, wherein the substrate surface opposite to the antireflection layer and the plastic film are bonded via an adhesive layer.

According to a tenth aspect of the present invention, at least one surface of the polarizing film is bonded to a surface of the anti-reflection film according to any one of the first to ninth aspects on the side opposite to the anti-reflection layer. It is characterized by the following.

The invention according to claim 11 is the first invention.
An adhesive layer is formed on the surface of the anti-reflection film according to any one of the above items 10 to 10 opposite to the anti-reflection layer, and a peelable protective film is bonded thereon.

[0019]

Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an example of the configuration of the antireflection film of the present invention. As shown in FIG. 1, the antireflection film of the present invention comprises a high refractive index layer (2b) made of an oxide having a different refractive index as an antireflection layer 2 on a transparent base material 1 mainly composed of borosilicate glass. ) And the low-refractive-index layer (2a) are alternately arranged, and a total of four layers are stacked so that the low-refractive-index layer is located on the uppermost layer. The structure having a water-repellent and oil-repellent layer 3 having water and oil repellency on the outermost surface and protecting the surface of the antireflection layer is shown.

The transparent substrate 1 used in the present invention is mainly composed of borosilicate glass, and the borosilicate glass is a transparent glass mainly composed of B ₂ O ₃ and SiO _2. Very low melting point compared to ordinary inorganic glass,
And has a low softening point. Optical characteristics also have a high transmittance of 85% or more. In particular, the softening point, which is a large index of the workability of the glass itself, is 1000 ° C. or less, and it is possible to lower the temperature by further mixing an inorganic compound other than the borosilicate glass component. It is suitable. Borosilicate glass can be reduced in thickness due to such characteristics, and when thinned to about 10 to 200 μm, it becomes possible to bend difficult with ordinary glass, and it is a flexible transparent film that can be wound in a film form. It becomes possible to produce a substrate.

The transparent substrate mainly composed of borosilicate glass used in the present invention can be produced, for example, by the method described below. FIG. 5 is a schematic view showing a method for producing a transparent base material mainly composed of borosilicate glass. FIG.
As shown in (1), glass raw materials are sequentially supplied from a glass raw material introduction unit 10. The glass raw material is gradually guided downward and is completely melted in the melting furnace 11. The molten glass material is
It is pressurized by its own weight and has a thickness of 10 to 20 at the extrusion nozzle 12.
It is formed into an arbitrary thickness and width within a range of 0 μm and extruded. The film-shaped molten transparent base material 14 is gradually cooled
After gradually cooling down and sufficiently lowering the temperature from the softening point,
The transparent base material 16 which is guided by the guide roll 15 and is in the form of a take-up roll is produced. The produced transparent substrate 16 can be wound up and has flexibility like plastic, but has a surface hardness close to that of glass and higher gas barrier properties than plastic films.

The anti-reflection layer 2 in the anti-reflection film of the present invention utilizes the coherence of light, and generally has a predetermined optical thickness nd (refractive index nx shape film) in order to obtain desired anti-reflection characteristics. It is composed of layers having a thickness d), and is formed by alternately stacking high refractive index layers and low refractive index layers. In the present invention, the number of layers is not particularly limited. Although FIG. 1 shows an example in which the number of layers is four, the number of antireflection layers is usually preferably two to six in terms of cost and antireflection effect.

As the high refractive index material constituting the high refractive index layer, a material having a refractive index of more than 1.9 is usually used. For example, titanium oxide, zirconium oxide, tantalum oxide,
An insulating oxide such as niobium oxide, hafnium oxide, or cerium oxide can be used.

Further, a transparent film having conductivity can be used for the high refractive index layer. Any material can be used as long as it is used for the transparent conductive film. For example, zinc oxide, indium oxide, tin oxide and the like can be used. Oxides and mixed oxides, and those obtained by further adding additional elements, particularly, ITO (mixed oxide of indium oxide and tin oxide) are preferable in terms of high conductivity, chemical stability, transparency, and the like. .

As a method for forming such a high refractive index layer, a vacuum film forming process such as a vacuum evaporation method, a reactive evaporation method, an ion beam assisted evaporation method, a sputtering method, an ion plating method, and a plasma CVD method can be used. However, any film forming method may be used.

On the other hand, as a low refractive index material constituting the low refractive index layer, a material having a refractive index of 1.5 or less is used. As such a material, it is preferable to use silicon oxide in consideration of optical performance and matching when a water / oil repellent layer is formed.

As a method for forming the low refractive index layer, a vacuum film forming process can be used as in the case of the high refractive index layer.

FIG. 2 is a sectional view showing another example of the structure of the antireflection film of the present invention. As shown in FIG. 2, when the antireflection layer is composed of three layers, a medium refractive index layer having a refractive index in the middle of the high refractive index layer and the low refractive index layer is often used. At this time, the layer configuration is such that a middle refractive index layer (2c), a high refractive index layer (2b), and a low refractive index layer (2a) are laminated in this order from the substrate side.

The middle refractive index layer uses an oxide that is neither a high refractive index layer nor a low refractive index layer. Alternatively, a layer having a refractive index of about 1.8 can be obtained by using the mixed oxide.

The antireflection film of the present invention is characterized in that at least one of the layers constituting the antireflection layer has a light absorbing property. FIG. 3 is a sectional view showing still another example of the configuration of the antireflection film of the present invention. As shown in FIG. 3, the light absorbing layer 4 is for adding high contrast display performance by using a light absorbing material as a material constituting the antireflection layer of the antireflection film. Further, in the case of a CRT, since the image display surface is charged, dust and the like are easily attached, and dirt is easily noticeable.
The conductive film is removed by dropping it to ground. Since the light absorbing material has conductivity, it is possible to satisfy both high contrast and charging.

The antireflection film of the present invention is characterized in that the antireflection layer has a refractive index smaller than that of the substrate. In order to form a substance having a refractive index lower than that of the film base material, a method of lowering the refractive index by using a material containing fluorine and a method of depositing fine particles or the like on the surface of the film to form pores, and mixing the air to lower the refractive index. It is roughly classified into a method of increasing the refractive index. When classified according to the material constituting the low refractive index layer, a method of curing an alkoxysilane by a sol-gel method,
There are a method using a fluorine-based organic material and a method using fine particles having a low refractive index.

The anti-reflection film of the present invention is characterized in that at least one layer having water and oil repellency is formed on the uppermost layer of the anti-reflection layer. 3, which has water and oil repellency, protects the surface of the anti-reflection layer, repels water, makes it difficult for dirt to adhere, and can easily wipe off dirt such as oil-based ink and fingerprints. Becomes

As a material for forming the water / oil repellent layer 3, various organic compounds can be used according to the degree of water repellency and oil repellency imparted to the water / oil repellent layer 3.

Preferred examples of the forming material exhibiting water repellency and oil repellency include fluorine-containing organic compounds. Particularly, a polymer compound of perfluorocarbon is suitable.

The water-repellent / oil-repellent layer 3 may be formed by a vacuum film forming process such as a vacuum deposition method, a sputtering method, an ion plating method, a plasma CVD method, or a plasma polymerization method, or a microgravure method, depending on the material for forming the layer. And various coating methods such as a screen coating method and a dip coating method in a wet process. The thickness of the water-repellent / oil-repellent layer is preferably set to 10 nm or less in order not to impair the function of the antireflection layer.

In the case of a CRT or the like, since it is required to prevent the CRT screen from scattering when the glass is broken, a plastic film can be bonded to a substrate made of borosilicate glass. Therefore, an anti-reflection layer is provided on the base material to provide water repellency. A plastic film is bonded via an adhesive layer to the surface of the anti-reflection film opposite to the anti-reflection layer on which the oil-repellent layer is laminated.

An optical functional film having an antireflection function can be obtained by laminating an optical functional film such as a polarizing film and the antireflection film of the present invention with a laminate or the like.

When an optical functional film is produced by laminating the antireflection film of the present invention with another plastic film, polarizing film, or the like, the antireflection film or optical functional film can be used for various displays including liquid crystal, CRT, and plasma displays. By sticking to the front plate of the display of the apparatus, the display is prevented from being scratched by abrasion, the display quality is improved, and the displayed image can be more clearly recognized.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to specific embodiments.

Example 1 An antireflection film having the layer structure shown in FIG. 1 was produced as follows. 100 μm thick borosilicate glass (DESAG, Germany)
, D263, n = 1.53). This antireflection film is formed of titanium oxide (n = 2.17) as the high refractive index layer 2b, silicon oxide (n = 1.46) as the low refractive index layer 2a, and the high refractive index layer 2b from the substrate side. Titanium oxide (n = 2.17) and silicon oxide (n = 1.46) as the low refractive index layer 2a were used. Each of the high refractive index layer and the low refractive index layer was formed by a plasma assisted EB evaporation method. The optical film thickness (nd) of each layer is approximately 30n titanium oxide from the substrate side.
m, silicon oxide 50 nm, titanium oxide 290 nm, and silicon oxide 130 nm. Further, a fluorine-based water / oil repellent layer 3 was formed on the outermost surface.

In this case, the optical film thickness of each layer was monitored by an optical film thickness monitor, and when the target light amount was reached, the film formation was stopped to obtain a predetermined optical film thickness.

FIG. 6 shows the spectral reflection characteristics of the obtained anti-reflection layer by absolute reflection measurement. Absolute reflectance is 0.6% or less between 430 nm and 770 nm. From this, there is an antireflection effect over a wide range.

Steel wool (Bonstar No. 000)
0, manufactured by Nippon Steel Wool Co., Ltd.)
A scratch resistance test was performed with a load of m ² . As a result, it was found that there was no flaw and that it had very excellent scratch resistance.

Example 2 An antireflection film having the layer structure shown in FIG. 2 was produced as follows. As a film substrate, an antireflection film composed of three layers was formed on a borosilicate glass having a thickness of 100 μm (D263, manufactured by DESAG, Germany), n = 1.53. This antireflection film is composed of a lanthanum oxide-aluminum oxide composite layer (n = 1.77) as the middle refractive index layer 2c, a titanium oxide (n = 2.17) as the high refractive index layer 2b, and a low refractive index from the substrate side. Silicon oxide (n = 1.46) was used as the rate layer 2a. These layers were formed by a plasma-assisted EB evaporation method. The optical thickness (nd) of each layer was about 95 nm for the middle refractive index layer 2c, about 230 nm for the high refractive index layer 2b, and about 130 nm for the low refractive index layer 2a. Further, a fluorine-based water / oil repellent layer 3 was formed on the outermost surface.

In this case, the optical film thickness of each layer was monitored by an optical film thickness monitor, and when the target light amount was reached, the film formation was stopped to obtain a predetermined optical film thickness.

FIG. 7 shows the spectral reflection characteristics of the obtained anti-reflection layer by absolute reflection measurement. Absolute reflectance is 0.4% or less between 450 nm and 700 nm. From this, there is a good antireflection effect.

Steel wool (Bonstar No. 000)
0, manufactured by Nippon Steel Wool Co., Ltd.)
A scratch resistance test was performed with a load of m ² . As a result, it was found that there was no flaw and that it had very excellent scratch resistance.

Example 3 An antireflection film having the layer structure shown in FIG. 3 was produced as follows. As a film base material, an antireflection film composed of two layers was formed on borosilicate glass (D263, n = 1.53, manufactured by DESAG, Germany) having a thickness of 100 μm. This antireflection film is laminated from the substrate side on the light-absorbing layer 4 and the low-refractive-index layer 2, silicon oxide (n = 1.46) as the low-refractive-index layer 2, and titanium nitride as the light-absorbing layer 4 And In each of these layers, the low-refractive-index layer was formed by a plasma-assisted EB evaporation method, and the light-absorbing layer was formed by a reactive sputtering method using a titanium target introduced with nitrogen gas. The optical thickness (nd) is approximately 125 nm for the low refractive index layer, and 14 nm for the light absorbing layer.
And Although the optical characteristics of the titanium nitride change depending on the measurement wavelength, when the wavelength λ = 450 nm, n = 1.
75, extinction coefficient k = 0.86, n = when λ = 550 nm
1.26, k = 1.26, λ = 650 nm, n =
1.15, k = 1.65. Further, a fluorine-based water / oil repellent layer 3 was formed on the outermost surface.

In this case, the optical film thickness of each layer was monitored by an optical film thickness monitor, and when the target light amount was reached, the film formation was stopped to obtain a predetermined optical film thickness.

The average reflectance of the obtained antireflection film was 0.33% between wavelengths of 450 nm and 650 nm, and the average transmittance was 68.2% in the same range.

The internal resistance was measured at a diagonal of A4 size and found to be 1.54 kΩ.

Comparative Example 1 As a hard coat layer, triacetylcellulose having a thickness of 80 μm formed of a polyfunctional acrylic resin by an ultraviolet irradiation curing method was used as a transparent base material, and four layers of antireflection were formed thereon. A film was formed.
Titanium oxide (n = 2.1) is applied to the high refractive index layer from the side of the substrate.
7) Using silicon oxide (n = 1.46) for the low refractive index layer, titanium oxide (n = 2.17) for the high refractive index layer, and silicon oxide (n = 1.46) for the low refractive index layer A total of four layers were laminated to form an antireflection layer. Each of the high refractive index layer and the low refractive index layer was formed by a plasma assisted EB evaporation method. The optical film thickness (nd) of each layer is approximately 60 nm for titanium oxide, 40 nm for silicon oxide,
00 nm and silicon oxide 140 nm. Further, a fluorine-based water / oil repellent layer 3 was formed on the outermost surface.

FIG. 8 shows the spectral reflection characteristics of the obtained antireflection layer by absolute reflection measurement. Absolute reflectance is 0.6% or less between 410 nm and 650 nm.

Steel wool (Bonstar No. 000)
0, manufactured by Nippon Steel Wool Co., Ltd.)
A scratch resistance test was performed with a load of m ² . As a result, it was found that there was almost no scratch and sufficient scratch resistance was obtained.

[0056]

According to the present invention, by using a base material mainly composed of borosilicate glass, which is different from the conventional polymer film, as the base material of the antireflection film, the hard coat film conventionally provided on the antireflection film can be obtained. It has become possible to provide a flexible antireflection film which does not require a layer, is excellent in mechanical strength such as abrasion resistance, and excellent in heat resistance. The antireflection film of the present invention eliminates the step of forming a hard coat layer, and can improve the production efficiency because the base material is excellent in heat resistance, and can produce a large amount of highly reliable products. When an optical function film is produced by laminating an anti-reflection film with another plastic film or polarizing film, etc., the anti-reflection film or the optical function film is adhered to the front panel of the display of the display device, thereby scratching the display. Thus, the display quality can be improved, and the displayed image can be more clearly recognized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a layer configuration of an antireflection film as an example of the invention.

FIG. 2 is a cross-sectional view illustrating a layer configuration of an antireflection film as an example of the invention.

FIG. 3 is a cross-sectional view illustrating a layer configuration of an antireflection film as an example of the invention.

FIG. 4 is a cross-sectional view illustrating an example of a layer configuration of a conventional antireflection film.

FIG. 5 is an explanatory view showing a method for producing a transparent substrate in the antireflection film of the present invention.

FIG. 6 is a spectral reflection characteristic diagram of the antireflection film obtained in Example 1.

FIG. 7 is a spectral reflection characteristic diagram of the antireflection film obtained in Example 2.

FIG. 8 is a spectral reflection characteristic diagram of the antireflection film obtained in Comparative Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 16 ... Transparent base material 2 ... Anti-reflection layer 3 ... Water / oil repellent layer 4 ... Light absorption layer 5 ... Hard coat layer 10 ... Glass raw material introduction part 11 ... Melting furnace 12 ... Extrusion nozzle 13 ... Cooling part 14 ... Film-like glass in the molten state 15: Guide roll

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H04N 5/72 G02B 1/10 A F term (reference) 2K009 AA06 AA07 BB02 CC03 CC26 CC42 DD02 DD03 DD04 DD07 EE00 EE03 4F100 AA17A AA17B AA17C AA17D AA17E AA20 AA21 AG00A AK52E AR00B AR00C AR00D AR00E BA02 BA03 BA05 BA06 BA10B BA10C CA23A EH662 JB04E JJ03 JK01 JK06 JL11E JL14 JN06B JN06C JN06D JN06E JN18B JN18C JN18D JN18E 4G059 AA20 AC04 AC30 EA01 EA03 EA04 EA05 EB03 EB04 FA07 FB01 FB03 GA02 GA04 GA12 GA16 5C058 AA01 AB05 BA08 BA30

Claims (11)

[Claims] 1. An anti-reflection film having an anti-reflection layer on at least one surface of a substrate, wherein the substrate comprises borosilicate glass as a main component. 2. The method according to claim 1, wherein the base material has a thickness of 10 to 2 that can be wound.
2. The anti-reflection film according to claim 1, wherein the anti-reflection film is a film-shaped substrate having a thickness of 00 [mu] m. 3. The anti-reflection film according to claim 1, wherein the base material is mainly composed of borosilicate glass to which an inorganic oxide other than the borosilicate glass component is added. 4. The anti-reflection film according to claim 1, wherein the anti-reflection layer has at least two layers composed of oxides having different refractive indexes. 5. The anti-reflection film according to claim 1, wherein at least one of the layers constituting the anti-reflection layer has a light absorbing property. 6. The method according to claim 1, wherein a refractive index of the antireflection layer is smaller than a refractive index of the substrate.
The anti-reflection film according to item. 7. The method according to claim 1, wherein at least one layer having water repellency and oil repellency is formed on the uppermost layer of the antireflection layer. Anti-reflection film. 8. The anti-reflection film according to claim 7, wherein the layer having water repellency and oil repellency is perfluorosilane. 9. The antireflection film according to any one of claims 1 to 8, wherein the substrate surface opposite to the antireflection layer and a plastic film are bonded via an adhesive layer. Anti-reflection film. 10. An anti-reflection film, characterized in that at least one surface of the polarizing film is bonded to the surface of the anti-reflection film according to claim 1 opposite to the anti-reflection layer. . 11. An adhesive layer is formed on the surface of the anti-reflection film according to any one of claims 1 to 10 opposite to the anti-reflection layer, and a peelable protective film is bonded thereon. An anti-reflection film, characterized in that: