Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2001-07-26
2003-11-18
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S421000, C428S448000, C428S451000
Reexamination Certificate
active
06649271
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an anti-static anti-reflective film 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-static anti-reflective film exhibiting superior anti-reflective property, abrasion resistance, 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 note-book-type personal computers and word processors, portable telephones, PHSs, various portable terminals, etc., as displays which are thin, light, and extremely versatile.
In the past, in such displays, although an anti-reflective layer having a low refractive index had been formed to prevent reflection on the surface, there was a problem in that contamination such as dust, etc., adhered by static electricity occurring on the surface, since an insulating resin is generally used in the anti-reflective layer or other members constituting the display. As methods for preventing static electricity on the surface of the display, specifically, a method in which an anti-static layer is formed by depositing or sputtering an extremely thin layer of a metal oxide such as ITO or a metal such as aluminum or tin; by dispersing whiskers and metal microparticles such as those of aluminum or tin, whiskers and microparticles such as those of antimony-doped metal oxide such as tin oxide, fillerized charge-transfer complexes produced between 7,7,8,8-tetracyanoxydimethane and an electron donor such as an organic cation or a metal ion in a polyester resin, an acrylic resin, an epoxy resin, or the like, and subsequently solvent-coating; by solvent-coating a camphor-sulfonic-acid-doped polypyrrol, polyaniline, etc.; or a method in which an anti-reflective layer or another layer having an anti-static property is formed by containing the above anti-static materials therein, were typically used.
However, since the above anti-static fine particles and anti-static agents are materials having a very high refractive index, the refractive index of an anti-static layer or a layer containing the anti-static agent is increased, and therefore there was a problem in that the anti-reflective property thereof was deteriorated. Additionally, there was also a problem in that deterioration of abrasion resistance on the layer occurs due to the containing of such anti-static fine particles or anti-static agents.
SUMMARY OF INVENTION
The present invention has been made in view of the above circumstances, and it is an object thereof to provide an anti-static anti-reflective film which exhibits not only superior optical properties and physical properties but also superior anti-static properties.
The inventor has conducted various research with respect to anti-static properties on the mostsurface of an anti-reflective film in order to prevent static electricity occurring on the surface of displays, etc., and consequently, he has found that a superior anti-static property of the film can be exhibited by containing cation-modified silicon compounds in a low refractive layer while conventional superior optical properties and physical properties are maintained.
Therefore, an anti-static anti-reflective film according to the present invention is characterized in that a low reflective layer is provided on the surface of a transparent substrate directly or via another layer, the low reflective layer is formed by curing at least a silicon compound, and the silicon compound includes cation-modified silicon compounds.
In the following, preferable embodiments of an anti-static anti-reflective film of the present invention will be explained in detail.
A. Transparent Substrate
As a transparent substrate employed in an anti-static anti-reflective film 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-weight 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 10 to 500 &mgr;m in consideration of the productivity thereof.
In addition, the adhesion between the low reflective layer or another layer provided thereunder 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 a Si deposition or the like.
B. Low Reflective Layer
A low reflective layer of the present invention is formed by curing at least a silicon compound, and preferably by curing a silica sol. The silica sol is a sol in which silica microparticles are dispersed in water or an organic solvent, and is produced by a method for condensation of an activated silicic acid which de-alkalizes an alkali metal ion in an alkaline salt of silicic acid by ion exchange, etc., or which neutralizes an alkaline salt of silicic acid with a mineral acid, or by a method for hydrolysis and condensation of an alkoxysilane in an organic solvent in the presence of a basic catalyst. Alternatively, an organic-solvent type silica sol (organosilica sol) obtained by replacing the water in an aqueous silica sol described above with an organic solvent by a distillation method may be employed. These silica sols can be employed in either an aqueous or organic-solvent condition. It is not necessary to completely replace the water with the organic solvent in the case of production of the organic-solvent type silica sol. The silica sol contains a solid component as SiO
2
in a concentration of 0.5 to 50% by weight. Various types of silica ultra-microparticles in the silica sol, such as in a spheroidal form, a needle form, a plate form, or the like can be employed.
In addition, it is desirable that the pH be nearly neutral in consideration of dispersiveness to solvent, etc., since the silica sol is generally used by dispersing in organic solvent. The particle size of the silica sol is preferably 5 to 500 nm, and is more preferably 5 to 300 nm. When the particle size of the silica sol is below 5 nm, a reduction of the reflective characteristics can be insufficiently obtained. In contrast, when the particle size of the silica sol exceeds 500 nm, the haze value is increased and the surface of the film is hazy white, and in addition, the anti-static property is undesirable.
In addition, in the silicon compound in the present invention, a cation-modified silicon compound which works as a film forming agent and an anti-static agent must be contained. Furthermore, it is preferable that this cation-modified silicon compound contain nitrogen, and in particular, that nitrogen be contained as a quarternary ammonium salt. Specifically, as a cation-modified silicon compound, octadecyl dimethyl [3-(trimethoxysilyl) propyl] ammonium chloride, N-(3-trimethoxysilylpropyl)-N-methyl-N,N-diallyl ammonium chloride, N,N-didecyl-N-methyl-N-(3-trimethoxysilylpropyl)
Arent Fox Kintner Plotkin & Kahn
Dawson Robert
Keehan Christopher M.
Tomoegawa Paper Co. Ltd.
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