Radiation imagery chemistry: process – composition – or product th – Diazo reproduction – process – composition – or product – Composition or product which contains radiation sensitive...
Reissue Patent
1997-01-03
2001-01-30
Chu, John S. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Diazo reproduction, process, composition, or product
Composition or product which contains radiation sensitive...
C430S007000, C430S197000, C430S270100, C430S281100, C430S288100, C430S910000, C430S176000
Reissue Patent
active
RE037033
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a pigment-dispersed composition for a color-filter (to be referred to as “pigment-dispersed color-filter composition” hereinafter). More specifically, it relates to a pigment-dispersed color-filter composition useful for the production of color filters of a liquid crystal display and a charge coupled device.
For producing a color filter of a liquid display, a dyeing method, a printing method and an electrodeposition method are known. In recent years, a photolithographic method using a pigment-dispersed photosensitive composition is particularly attracting attention in terms of color purity, dimensional accuracy and process resistance (“Color Liquid Crystal Display” page 173, edited by Shunsuke Kobayashi, published by Sangyotosho, 1990).
However, the photolithographic method using a pigment-dispersed photosensitive composition having a variety of advantages is still required to have further improved performances for stably producing highly accurate and fine color filters. That is, a highly accurate and fine pixel is liable to peel off a substrate in a development step when a colored pixel of a color filter is formed by applying a pigment-dispersed photosensitive composition to the substrate, exposing the coating and developing it, and the color filter is thus liable to have a deficiency. On the other hand, when an attempt is made to improve the adhesion of a highly accurate and fine pixel to a substrate, the solubility of a non-pixel portion which should be dissolved away in a developer solution tends to decrease, and a so-called surface soiling and resin-remaining are liable to occur. In this case, it is general practice to apply a physical stimulus by rubbing the coating with a soft substance such as sponge or the like for removing the surface soiling and remaining resin. However, this practice is undesirable, since it involves toughening and occurrence of dust on the color filter surface, which ends up in a decrease in the yields of color filters.
When a color filter is produced from a radiation-sensitive composition, it is conventionally produced as follows. A light shielding layer in a desired pattern is formed on a glass substrate on which an SiO
2
film or the like has been formed to prevent the elution of sodium ion. A radiation-sensitive composition is spin-coated on the light shielding layer to form a coating, and the coating is heated (prebaked) and dried. The so-prepared dried coating (to be sometimes referred to as “dry coating” hereinafter) is exposed and developed to form a pixel of each color.
In the so-obtained dry coating formed on the substrate, the thickness of its central portion and the thickness of its marginal portion sometimes differs by 0.2 &mgr;m or more, and striation (streaks) sometimes occurs. It is therefore difficult to produce a dry coating having a uniform thickness. Further, an unevenness having a depth of approximately 300 to 500Å is sometimes formed on the dry coating surface, and the dry coating surface is inferior in surface smoothness. When the surface of the coating formed by spin coating has a nonuniform thickness or fine evenness, a color filter obtained by developing the dry coating has inferior transparency.
For this reason, in forming a color filter on a substrate surface, it is therefore desired to develop a radiation-sensitive composition for a color fitter, which is capable of forming a dry coating having a uniform thickness and having an excellently smooth surface.
When a conventional color filter is produced from a radiation-sensitive composition, a coating of the composition is developed with an alkaline aqueous solution. In this case, an undissolved substance from the radiation-sensitive composition sometimes remains on a non-pixel portion of the substrate. When an undissolved substance from the radiation-sensitive composition remains on the non-pixel portion of the substrate, the color filter shows a decline in transmittance or a decrease in contrast. When a color filter is produced, generally, pixels of three colors are consecutively produced by consecutively forming coatings of radiation-sensitive compositions each of which has a hue of red, blue or green. However, when an undissolved substance of the radiation-sensitive composition for forming a pixel of one of the colors remains on the substrate, a pixel of other color subsequently formed on the substrate where the undissolved substance remains is inferior in adhesion to the substrate and hence, it may peel off. The so-remaining undissolved radiation-sensitive composition on a non-pixel portion of the substrate surface is one of the reasons for decreasing the yields of color filters.
It is therefore an object of the present invention to provide a novel pigment-dispersed color-filter composition.
It is another object of the present invention to provide a novel pigment-dispersed color-filter composition which gives pixels having excellent adhesion to a substrate and is free of surface soiling and a remaining composition in development.
It is further another object of the present invention to provide a pigment-dispersed color-filter composition which gives a color filter having little difference in thickness between its central portion and its marginal portion and having excellent surface smoothness.
Further, it is another object of the present invention to provide to a pigment-dispersed color-filter composition which is capable of uniformly forming pixels having excellent adhesion to a substrate without leaving an undissolved substance of the composition on a non-pixel portion when a color filter is produced.
It is still further another object of the present invention to provide a novel pigment-dispersed color-filter composition useful for producing a color filter for a liquid crystal display and a charge coupled device.
Other objects and advantages of the present invention will be apparent from the following description.
According to the present invention, the above objects and advantages of the present invention will be achieved, first, by a novel pigment-dispersed color-filter composition (to be referred to as “first composition” hereinafter) comprising:
(A) an alkali-soluble block copolymer composed of a block having an acid group and a block having no acid group,
(B) a radiation-sensitive compound, and
(C) a pigment.
In the first composition of the present invention, an alkali-soluble block copolymer (A) composed of a block having an acid group and a block having no acid group is used as a binder.
The block having an acid group is composed of a homopolymer formed from at least one monomer having an acid group such as an ethylenically unsaturated carboxylic acid and ethylenically unsaturated sulfonic acid, a copolymer of these or a copolymer formed from the above monomer having an acid group and a monomer having no acid group and being copolymerizable with the above monomer.
In view of ease in controlling the polymerization degree, preferred as the block having an acid group is a homopolymer of an ethylenically unsaturated carboxylic acid or a copolymer formed from an ethylenically unsaturated carboxylic acid and a monomer having no acid group and being copolymerizable therewith.
The ethylenically unsaturated carboxylic acid preferably includes acrylic acid, methacrylic acid, crotonic acid, iraconic acid, maleic acid, fumaric acid, monomethyl maleate and monomethyl fumarate.
The ethylenically unsaturated sulfonic acid includes isoprenesulfonic acid and styrenesulfonic acid.
The monomer having no acid group and being copolymerizable with the above monomer includes aromatic vinyl compounds such as styrene, &agr;-methylstyrene and vinyltoluene; ethylenically unsaturated carboxylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate and benzyl (meth)acrylate; carboxylic acid vinyl esters such as vinyl acetate and vinyl propionate; vinyl cyanides such as (meth)acrylonitrile and &agr;-chloroacrylonitrile; and aliphatic conjugated dien
Bessho Nobuo
Masuko Hideaki
Tajima Yusuke
Takinishi Fumitaka
Yokoyama Yasuaki
Chu John S.
JSR Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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