Optical: systems and elements – Glare or unwanted light reduction
Reexamination Certificate
2001-04-06
2003-01-14
Sikder, Mohammad (Department: 2872)
Optical: systems and elements
Glare or unwanted light reduction
C359S602000, C359S603000, C359S604000, C359S608000
Reexamination Certificate
active
06505942
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an anti-reflection material and to a polarization film employing the anti-reflection material, which is suitable for use in displays such as liquid crystal displays (LCDs), plasma displays (PDPs), CRTs, ELs, etc., and in particular, relates to an anti-reflection material and to a polarization film employing the anti-reflection material, having superior anti-glare properties, anti-reflection properties, and anti-static properties.
Displays typified by LCDs, PDPs, CRTs, and ELs are widely used in various fields such as television and computer technologies, and have been developed rapidly. In particular, LCDs are in remarkably common use in lap-top-type personal computers and word processors, portable telephones, PHSs, various portable terminals, etc., as displays which are thin, light, and extremely versatile.
Generally, as shown in
FIG. 3
, LCDs have a construction in which a back light
40
is arranged at the rear (the lower side in
FIG. 3
) of a liquid-crystal display panel
30
which is a multilayer lamination. In the liquid-crystal display panel
30
, a liquid crystal cell
32
and a polarization film
33
having a low reflection layer are laminated on the front (the upper side in
FIG. 3
) of a TFT glass substrate
31
, in that order, and a polarization film
34
without a low reflection layer is laminated on the rear of the TFT glass substrate
31
. The polarization films
33
and
34
have a basic construction in which a transparent substrate
36
consisting of TAC (triacetylcellulose), etc., and a protective material
37
are laminated on the front and the rear of a polarization material
35
consisting of a PVA (polyvinyl alcohol) film, etc., respectively. In the polarization film
33
having a low reflection layer, an anti-glare layer
38
and a low reflection layer
39
are laminated in that order. In the anti-glare layer
38
, for example, a UV-curable resin coating material in which an acrylic compound is contained as a primary material can be employed, and in the low reflection layer
39
, for example, a fluorine-containing resin coating material can be employed.
Furthermore, in such display, there was a problem in that contaminants such as dust, etc., adhered due to static electricity occurring at the surface thereof. As a method for preventing the static electricity on the surface of this display, specifically, in a display having the above construction, {circle around (1)} a method in which an electroconductive material having an anti-static effect is used as a material for forming the anti-glare layer; {circle around (2)} a method in which electroconductive fillers are contained in the anti-glare layer; and {circle around (3)} a method in which an electroconductive material is used as a material for forming the low reflection layer, can be mentioned.
However, in the above method {circle around (1)}, problems in physical properties such as decreasing of surface hardness, lack of adhesion to saponified TAC which is a transparent substrate, etc., are caused, although the anti-static property is improved. In the above method {circle around (2)}, problems in optical properties such as increasing of turbidity in the anti-glare layer, decreasing of permeability thereon, etc., are caused. In addition, also in the above method {circle around (3)}, there is a problem in practice, since although the anti-static property is improved, disappearance of the low reflection property and decreasing of the surface hardness are caused.
SUMMARY OF INVENTION
Therefore, the present invention has been made in view of the above circumstances, and it is an object thereof to provide an anti-reflection material which can not only exhibit superior anti-glare properties, anti-reflection properties, and durability, but can also exhibit anti-static properties while retaining the above properties. In addition, it is also an object thereof to provide a polarization film employing the above anti-reflection material, and in particular, performance of full color liquid crystal display is thereby drastically improved.
The inventors have conducted various research with regard to anti-static properties on the frontmost surface of anti-reflection material in order to prevent electrostatic charge from occurring on the surface of a display, etc., and consequently, they have found that the anti-static property can be obtained while retaining superior optical properties and physical properties before treating, by carrying out a surface hydrophilizing treatment such as a corona treatment, etc., on the frontmost surface of a conventional anti-reflection material having superior optical properties and physical properties.
Therefore, an anti-reflection material according to the present invention is characterized in that an anti-glare layer is provide on the surface of a transparent base substrate directly or via another layer, a low reflection layer having a lower reflective index than that of the anti-glare layer is provided on the surface of the anti-glare layer, and the frontmost surface of the anti-reflection material is subjected to a surface hydrophilizing treatment. In the following, preferable embodiments of the present invention will be explained in detail.
(1) Anti-reflection Material
A. Transparent Substrate
As a transparent substrate employed in an anti-reflection material according to the present invention, a conventional transparent film, glass, etc., can be employed. Specifically, various resin films such as polyethylene terephthalate (PET), triacetyl cellulose (TAC), polyacrylate, polyimide, polyether, polycarbonate, polysulfone, polyether sulfone, cellophane, aromatic polyamide, polyethylene, polypropylene, polyvinyl alcohol, and the like, and glass based materials such as fused glass, soda glass, and the like can be preferably employed. For PDPs and LCDs, PET and TAC are preferred.
The higher the transparency of the transparent substrate, the better the transparent substrate. The light transmittance (Japanese Industrial Standard C-6714) is preferably 80% or more, and is more preferably 90% or more. In the case in which the transparent substrate is employed in a compact and light-weighting liquid-crystal display, the transparent substrate is preferably in the form of a film. It is desirable that the transparent substrate be thin from the standpoint of being light-weight, and it is preferred that the thickness of the transparent substrate be preferably 1 to 5 &mgr;m in consideration of the productivity thereof.
In addition, the adhesion between the anti-glare layer and the transparent substrate can be improved by surface-treatment of the transparent substrate such as an alkaline treatment, corona treatment, plasma treatment, fluorine treatment, sputtering treatment, or the like, a coating, on the transparent substrate, of a surface active agent, a silane coupling agent, or the like, or a surface-modification-treatment such as an Si deposition or the like.
B. Anti-glare Layer
Next, an anti-glare layer in the present invention is explained.
As a resin for forming the anti-glare layer, a resin cured by means of radiation or heat, or a combination thereof, can be employed. As a radiation curable resin, compounds appropriately mixed with monomers, oligomers, or prepolymers having polymeric unsaturated bonds such as for an acryloyl group, methacryloyl group, acryloyloxy group, methacryloyloxy group, etc., can be employed. As a monomer, styrene, methyl acrylate, methyl methacrylate, methoxy polyethylene methacrylate, cyclohexyl methacrylate, phenoxy ethyl methacrylate, ethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, and the like, can be mentioned. As an oligomer or prepolymer, an acrylate such as polyester acrylate, polyurethane acrylate, epoxy acrylate, polyether acrylate, alkyd acrylate, melamine acrylate, silicone acrylate, or the like, an unsaturated polyester, an epoxy-type compound, or the like, can be mentioned. These can be employed alone or in combination. In the case in which
Murata Chikara
Ohishi Kazuya
Arent Fox Kintner & Plotkin & Kahn, PLLC
Sikder Mohammad
Tomoegawa Paper Co. Ltd.
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