Anti-reflection film and optical members using the same

Details Anti-reflection film and optical members using the same Anti-reflection film and optical members using the same

2001-12-07

2003-12-09

Dawson, Robert (Department: 1712)

Stock material or miscellaneous articles

Composite

Of silicon containing

C428S447000, C428S448000, C528S028000, C528S042000

Reexamination Certificate

active

06660392

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an anti-reflection film with good stain resistance, and optical members using the film.
2. Description of the Prior Art
On anti-reflection films which are generally formed on the surface of display units are liable to be stained with dirt from hands, fingerprint, sweat, or hairdressing. For this, reflectance at surface may change, and the stain may become conspicuous and look white, making unclear the contents of indication, so that there is a problem that stains stand out compared to mere transparent plates. Accordingly, it has been sought to provide an anti-reflection film excellent in stain resistance and stain-cleanabillty for a long period of time.
With the aim of improving the stain resistance, Japanese Post-Examination Patent Publication (kokoku) No. 6-5324 discloses an optical article with anti-stain resistance, comprising an anti-reflection layer of a monolayered or multilayered inorganic layer having a surface layer formed by PVD (Physical Vapor Deposition) and mainly comprised of silicon dioxide, and a layer of a cured product of an organopolysiloxane polymer or a perfluoroalkyl group-containing polymer formed on said anti-reflection layer.
However, if to this optical article is attached a human-derived stain such as dirt from hands or fingerprint, the stain can be wiped off with common tissue paper with difficulty. Furthermore, when the tissue paper is used, the stain may be pressed and extended on the thin anti-reflection film, or when the anti-reflection film is scraped strongly with the paper it may be damaged. Thus, there is a problem that the stain cannot be removed satisfactorily.
SUMMARY OF THE INVENTION
In view of the situation described above, an object of the present invention is to provide an anti-reflection film with good performance in stain resistance, wipe off cleanability, mar resistance, and water repellency, and good durability of these properties, and also to provide optical members having the film on a supporting substrate and good performance in the same properties.
The present inventors have studied in various ways, and as a result have discovered that formation of a cured product layer of a particular fluorine-containing silazane compound described below as the surface layer on the anti-reflection film enables achievement of the above stated object, thus leading to the present invention.
Thus, as a first aspect, the present invention provides an anti-reflection film comprising an inorganic anti-reflection layer comprising a silicon dioxide-based inorganic layer and having a monolayer structure or plural-layer structure, and a stain-resistant layer provided as a surface layer, said stain-resistant layer comprising a cured product of a fluorine-containing silazane compound represented by the formula (1):
[(RfQ)
a
Si(R
1
)
b
(NR
2
)
4−a−b/2
]
1
·[(RfQ)
c
Si(R
1
)
d
O
4−c−d/2
]
m
·[(RfQ)
a
Si(R
1
)
f
(NR
2
)
g/2
O
h/2
]
n
  (1)
wherein R
1
are the same or different and each represent a hydrogen atom, or an unsubstituted or substituted monovalent hydrocarbon group; R
2
are the same or different and each represent a hydrogen atom or an alkyl group; Rf are the same or different and each represent a perfluoroalkyl group with 1-20 carbon atoms or perfluoroalkylether group with 2-35 carbon atoms; Q is a divalent organic group with 2-5 carbon atoms; in each of the first structural units, independently, a represents an integer of 1-3, and b is an integer of 0-2, provided that a+b represents an integer of 1-3; in each of the second structural units, independently, c represents an integer of 0-2, and d is an integer of 1-3, provided that c+d represents an integer of 1-3; in each of the third structural units, e and f independently represent an integer of 0-2, and g and h each represents an integer of 1 or 2, provided that e+f+g+h=4; and l, m and n are each a number of 1 or greater.
The fluorine-containing silazane compound is a block polymer containing blocks of Si—N units and Si—O units.
As a second aspect, the present invention provides an optical member comprising a supporting substrate and said anti-reflection film formed on the supporting substrate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will now be described in detail.
The anti-reflection film according to the present invention comprises an inorganic anti-reflection layer comprising a silicon dioxide-based inorganic layer and having a monolayer structure or plural-layer structure, and a stain-resistant layer provided as a surface layer, and the stain-resistant layer is comprised of a cured product of the fluorine-containing silazane compound having the formula (1). The inorganic anti-reflection layer is firstly described.
Inorganic Anti-Reflection Layer
The inorganic anti-reflection layer in the anti-reflection film is a part substantially responsible for the anti-reflection function, and it may has a monolayer structure or plural-layer structure.
Accordingly, the inorganic anti-reflection layer may be formed as an anti-reflection layer having any of the structures described in, for example, A. VASICEK, OPTICS OF THIN FILMS, p. 159-283, NORTH-HOLLAND PUBLISHING COMPANY, AMSTERDAM (1960), Japanese Laid-Open Patent Publication (kokai) Nos. 58-46301, 59-49501, 59-50401, and 1-294709, and Japanese Post-Examination Patent Publication (kokoku) No. 6-5324.
As the inorganic compound used for forming the inorganic anti-reflection layer, can be used inorganic oxides, inorganic halides, and their composites, The inorganic compound specifically includes, e.g., inorganic oxides such as SiO
2
, ZrO
2
, Al
2
O
3
, Y
2
O
3
, and TiO
2
, inorganic fluorides such as MgF
2
, BaF
2
, CaF
2
, LaF
2
, LiF, NaF, and SrF
2
, and their composites.
When the inorganic anti-reflection layer has a monolayer structure, it is preferably a silicon dioxide-based inorganic layer in view of a high surface hardness and good adhesion to the stain-resistant layer being obtained. When It is a plural-layer structure, the layer adjacent to the surface layer is preferably a silicon dioxide-based inorganic layer.
The inorganic anti-reflection layer can be formed according to the production processes described below as a layer of one or more inorganic compounds or a layer of a mixture of an inorganic compound described above and a binder polymer. When it is formed as a layer of a mixture of an inorganic compound described above and a binder polymer, the mixture preferably contains the inorganic compound in a quantity of 30% or more from the viewpoint of hardness and surface stain resistance. As the binder polymer, any suitable polymer can be used and there is no particular limitation: however, a variety of organosilicon compounds and their hydrolysates capable of forming organopolysiloxanes are preferred in view of hardness, etc.
The formation of the inorganic anti-reflection layer can be performed by a suitable method for forming thin coating film. e.g., PVD methods such as vacuum deposition, spattering, and ion plating, fluid coating methods such as spin coating, dip coating, curtain flow coating, roll coating, spray coating, flow coating.
In the PVD methods, inorganic oxides such as SiO
2
and inorganic halides such as MgF
2
are preferably used. Especially the silicon dioxide-based inorganic layer to be present on the side of the surface layer is preferably formed by a PVD method as a layer mainly comprised of silicon dioxide from the viewpoint of a higher surface hardness and a good adhesion with the stain-resistant layer formed as the surface layer.
The anti-reflection layer preferably has a plural-layer structure in view of the anti-reflection effect, in particular a plural-layer structure inside which one or more layers are present which have a higher refractive index than the silicon dioxide-based inorganic layer which is present on the side of the surface layer. In that case, thickness, refractive index, etc. of each la

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