Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1999-05-03
2001-02-20
Berman, Susan (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S080000, C522S085000, C522S110000, C522S113000, C522S114000, C522S120000, C522S121000
Reexamination Certificate
active
06191184
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to radiation-setting compositions which are suitable for constructing spacers or protective layers in liquid crystal display (LCD) elements and solid-camera elements.
BACKGROUND OF THE INVENTION
A liquid crystal display element is usually provided with a spacer between a color filter and an array substrate to give a uniform film thickness of a liquid crystal layer. It has been conventionally conducted to form such spacers by adding spherical particles such as polymethyl methacrylate or spherical silica to the liquid crystal layer to secure the formation of voids of 3 to 10 &mgr;m.
These spherical particles would migrate within the liquid crystal layer. When the liquid crystal is pushed with a finger, etc., the voids vary due to the migration of the particles, and thereby the liquid crystal thickness is changed. This phenomenon sometimes results in troubles such as color-bleeding in the liquid crystal display or image distortion.
Thus, it is proposed to form spacers by using photosensitive resin compositions as a substitute for the spherical particles. It is possible to use, as a substitute for a spacer, a partly thickened photosensitive, colored composition for forming a color filter. Although such a colored composition layer containing a pigment can be formed simultaneously with the formation of the color filter, there arise some problems, i.e., a need of a high exposure amount for setting and insufficient setting of the bottom of the colored composition layer. In this case, moreover, the production cost is elevated due to use of an expensive pigment and a need of an additional step for preparing a pigment dispersion. Therefore, it has been required to develop a transparent photosensitive composition for forming the above-mentioned spacer.
On the other hand, JP-A-7-248625 discloses a radiation-setting composition for forming permanent films, for example, interlayer insulation films and protective films for liquid crystal displays with the use of a copolymer of an unsaturated carboxylic acid with a polymerizable compound containing epoxy group. (The term “JP-A” as used herein means an “unexamined published Japanese patent application”.) To achieve desired physical properties by this technique, however, heat setting should be performed after the formation of a photosensitive layer, which takes a long time usually. This technique suffers from another disadvantage that since it is necessary to use a carboxylic acid or an acidic component as a substitute therefor, the epoxy ring undergoes thickening or solidifying reactions during storage.
SUMMARY OF THE INVENTION
An object of the present invention, which has been completed to solve the problems encountering in the prior art as described above, is to provide radiation-setting compositions suitable for the formation of LCD spacers which are excellent in photosetting properties (requiring no heat-setting) and development properties, have high adhesiveness to substrates and excellent mechanical characteristics, remain stable over a long storage time and show excellent environmental condition-dependency.
Another object of the present invention is to provide radiation-setting compositions suitable for the formation of LCD protective layers which are excellent in photosetting properties (requiring no heat-setting) and development properties and have high adhesiveness to substrates and excellent mechanical characteristics.
The present inventors have effected intensive studies and consequently found out that the above objects can be achieved by using radiation-setting compositions of the constitution as specified below.
(1) A radiation-setting composition for LCD spacers which comprises:
(A) a (meth)acrylic acid-based copolymer having an acid value of 30 to 200 and a glass transition temperature of −30 to 180° C.;
(B) a (meth)acrylate-based compound obtained by copolymerizing a monomer represented by the following formula (I) with a monomer at least having an acidic group;
(C) a radiation-sensitive compound; and
(D) a solvent:
wherein R represents a hydrogen atom or a methyl group; and R
1
to R
5
each represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 7 carbon atoms or an aryl group having 6 to 12 carbon atoms.
Preferred embodiments of the present invention are shown below.
(2) The radiation-setting composition for LCD spacers as described in the above (1), wherein said (meth)acrylic acid-based copolymer (A) is one represented by the following formula (2-1), (2-2) or (2-3) and having a weight-average molecular weight (Mw) of 3,000 to 300,000.
wherein R
7
represents an alkyl group with 1 to 18 carbon atoms, a phenyl group having an alkyl group with 1 to 4 carbon atoms, a phenyl group having an alkoxy group with 1 to 4 carbon atoms, an aryl group with 6 to 12 carbon atoms or an aralkyl group with 7 to 12 carbon atoms; R
8
to R
10
each represents a hydrogen atom or a methyl group; n is 2 or 3;
a, b: a/b=5/5 to 9/1;
c, d, e: c/(d+e)=5/5 to 9/1, d/e=9/1 to 2/8; and
f, g, h, k: (f+k)/(g+h)=5/5 to 9/1, g/h=9/1 to 2/8, f/k=9/1 to 1/9.
(3) A radiation-setting composition for LCD protective layers which comprises:
(A) a (meth)acrylic acid-based copolymer represented by the formula (2-1), (2-2) or (2-3) as set forth in the above (2), having a weight-average molecular weight (Mw) of 3,000 to 300,000 and having an acid value of 30 to 200 and a glass transition temperature of −30 to 180° C.;
(B) a (meth)acrylate-based compound obtained by copolymerizing a monomer represented by the formula (I) as set forth in the above (1) with a monomer at least having an acidic group;
(C) a radiation-sensitive compound; and
(D) a solvent.
According to the present invention, use of the radiation-setting compositions of the above constitutions makes it possible to control the film thickness and give a uniform film thickness. As a result, excellent LCD spacers having desired patterns can be obtained and color bleeding in the liquid crystal display or image distortion can be prevented. The radiation-setting compositions of the above constructions are also excellent in characteristics for LCD protective layers.
DETAILED DESCRIPTION OF THE INVENTION
Now, the present invention will be described in greater detail.
(A) (meth)acrylic acid-based copolymer having acid value of 30 to 200 and glass transition temperature of −30 to 180° C. (referred to also as copolymer (A)):
This copolymer (A) is a linear organic polymer which is soluble in organic solvents and aqueous solutions of weak alkalis and satisfies the above-mentioned requirements. The acid value of the copolymer (A) may be regulated to 30 to 200 by bonding an acidic group (for example, a carboxyl group or a sulfonic acid group) or a hydroxyl group into the side chain. A preferable example of the acidic group is the carboxylic group. The acid value of the copolymer (A) preferably ranges from 50 to 150, still preferably from 80 to 120. The glass transition temperature of the copolymer (A) preferably ranges from −10 to 150° C., still preferably from 0 to 130° C.
The glass transition temperature of this copolymer is expressed in the molar-weighted average of the glass transition temperatures of homopolymers, while the acid value thereof is a calculated value.
Examples of the copolymer (A) include 2-hydroxypropyl (meth)acrylate/polystyrene macromonomer/benzyl methacrylate/methacrylic acid copolymer, 2-hydroxy-3-phenoxypropyl acrylate/polymethyl methacrylate macromonomer/benzyl methacrylate/methacrylic acid copolymer, 2-hydroxyethyl (meth)acrylate/polystyrene macromonomer/methyl methacrylate/methacrylic acid copolymer and 2-hydroxyethyl (meth)acrylate/polystyrene macromonomer/benzyl methacrylate/methacrylic acid copolymer, which each satisfies the requirements of acid value and glass transition temperature as specified above as described in JP-A-7-140654.
It is preferable that the copolymer (A) is one represented by the formula (2-1), (2-2) or (2-3) as given
Masaki Yoshihisa
Okita Tsutomu
Suzuki Nobuo
Berman Susan
Fuji Photo Film Co. , Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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