Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Reexamination Certificate
2001-06-04
2003-09-02
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
C428S328000, C428S331000, C428S343000, C428S354000, C428S483000, C428S500000
Reexamination Certificate
active
06613426
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a very fine anti-glare hard coat film and, more particularly, to a very fine anti-glare hard coat film which provides excellent visibility when the film is used for various types of displays since the film provides an excellent anti-glare property to the displays such as very fine liquid crystal displays without deterioration in the quality of displayed images and can also be used as a film for protecting surfaces since the film has a great surface hardness.
2. Description of Related Art
Liquid crystal displays used for displaying images are recently becoming very fine so that quality of images is further improved. Due to this tendency of becoming very fine, it is required that components used for liquid crystal displays have a sufficient high quality. Specific examples of such components include anti-glare hard coat films.
When a display such as a CRT or a liquid crystal display is used, light from the outside is occasionally reflected at the surface of the display (so-called glare) and difficulty arises in watching images on the display. In particular, as the size of flat panel displays increases recently, solving the above problem is becoming more important.
To solve the above problem, various methods for preventing glare (anti-glare methods) have been used for various types of display. In an example of such methods for preventing glare, roughness is formed on the surface of hard coat films used for polarizing plates in liquid crystal displays and protective hard coat films for various types of display. The anti-glare methods for hard coat films can generally be divided into (1) methods in which roughness is formed on the surface of a hard coat film by a physical means during curing for forming a hard coat layer and (2) methods in which a filler is mixed into a hard coat material which is used for forming a hard coat layer.
Between these two types of method, the latter method in which a filler is mixed into a hard coat material is mainly used and silica particles are mainly used as the filler. Silica particles are used because whiteness of the obtained hard coat film is low and dispersion is excellent when silica particles are mixed into a hard coat material.
However, when the liquid crystal display is very fine, using a conventional anti-glare hard coat film which is not very fine (which has a rough feel) as the anti-glare hard coat film causes a problem in that the quality of images inevitably deteriorates even when the liquid crystal display itself is very fine. Therefore, it is necessary that a very fine anti-glare hard coat film should be used for achieving the high quality of images which should be obtained by the very fine liquid crystal display.
In conventional anti-glare hard coat films, in general, silica particles having an average diameter of 1 to 2.5 &mgr;m have been used. Although these silica particles provide an excellent anti-glare property, the silica particles cannot satisfy the requirements of recent liquid crystal displays which are becoming very fine and the quality of images is held poor.
As described above, it is the actual present situation that no anti-glare hard coat films which can provide the excellent anti-glare property to recent very fine liquid crystal displays without causing deterioration in the quality of images are found among anti-glare hard coat films using silica particles having an average diameter of 1 to 2.5 &mgr;m singly as the filler.
Methods (1) described above in which the roughness is formed by a physical means during curing of a hard coat layer have drawbacks in that the operation of forming the roughness is complicated and that this methods cause insufficient visibility similarly to the method described above.
SUMMARY OF THE INVENTION
The present invention has an object of providing a very fine anti-glare hard coat film which provides an excellent anti-glare property to displays such as very fine liquid crystal displays without deterioration in the quality of displayed images and, therefore, excellent visibility when the film is used for various types of displays and can also be used as a film for protecting surfaces.
As the result of extensive studies by the present inventors to develop a very fine anti-glare hard coat film having the above excellent functions, it was found that the object can be achieved by a very fine anti-glare hard coat film which comprises a hard coat layer comprising a resin cured by an ionizing radiation and, in specific amounts, silica particles having an average diameter of 0.5 to 5 &mgr;m and fine particles having an average diameter of 1 to 60 nm and has a haze of a specific value or greater. The present invention has been completed based on the knowledge.
The present invention provides:
(1) A very fine anti-glare hard coat film which comprises a base film and a hard coat layer disposed on the base film and has a haze of 3% or greater, wherein the hard coat layer comprises (A) a resin cured by an ionizing radiation and, per 100 parts by weight of the resin, 2 to 25 parts by weight of (B) silica particles having an average diameter of 0.5 to 5 &mgr;m and 10 to 200 parts by weight of (C) fine particles having an average diameter of 1 to 60 nm;
(2) A film described in (1), which has a 60° gloss of 100 or smaller;
(3) A film described in any of (1) and (2), which has a clarity of vision through of 100 or greater;
(4) A film described in any of (1) to (3), which has a total light transmittance of 70% or greater;
(5) A film described in any of (1) to (4), which comprises a layer for preventing reflection disposed on the hard coat layer; and
(6) A film described in any of (1) to (5), which comprises an adhesive layer disposed on a face of the base film opposite to a face on which the hard coat layer is disposed.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The base film in the very fine anti-glare hard coat film of the present invention is not particularly limited and a suitable plastic film can be selected from conventional plastic films which are used as the base film in optical hard coat films. Examples of the plastic film include films of polyesters, such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene films, polypropylene films, cellophane, diacetylcellulose films, triacetylcellulose films, acetylcellulose butyrate films, polyvinyl chloride films, polyvinylidene chloride films, polyvinyl alcohol films, ethylene-vinyl acetate copolymer films, polystyrene films, polycarbonate films, polymethylpentene films, polysulfone films, polyether ether ketone films, polyether sulfone films, polyether imide films, polyimide films, fluororesin films, polyamide films and acrylic resin films.
The base film may be transparent or translucent and may be colored or colorless. These properties can be suitably selected in accordance with the application. For example, when the hard coat film is used as a protective film of a liquid crystal display, a colorless transparent film is preferable as the base film.
The thickness of the base film is not particularly limited and suitably selected in accordance with the situation. The thickness is generally in the range of 15 to 250 &mgr;m and preferably in the range of 30 to 200 &mgr;m. One or both surfaces of the base film may be treated, for example, by oxidation or by a treatment of forming rough surfaces, where desired, so that adhesion with layers disposed on the surfaces is enhanced. Examples of the treatment of the surface by oxidation include the treatment by corona discharge, the treatment by chromic acid (a wet process), the treatment by flame, the treatment by heated air or irradiation by ultraviolet light in the presence of ozone. Examples of the treatment of forming rough surfaces include the treatment by sand blasting and the treatment with a solvent. The surface treatment is suitably selected in accordance with the type of the base film. In general, the treatment by corona discharge is preferable from the standpoint of the effect
Maruoka Shigenobu
Onozawa Yutaka
Shoshi Satoru
Ahmed Sheeba
Frishauf Holtz Goodman & Chick P.C.
Lintec Corporation
Thibodeau Paul
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