U.S. patent application number 09/750789 was filed with the patent office on 2001-05-31 for pigment composition and colored photosensitive composition.
Invention is credited to Morimoto, Shinichiro, Takeda, Akihiko, Yoshimura, Kousaku.
Application Number | 20010002415 09/750789 |
Document ID | / |
Family ID | 26449984 |
Filed Date | 2001-05-31 |
United States Patent
Application |
20010002415 |
Kind Code |
A1 |
Takeda, Akihiko ; et
al. |
May 31, 2001 |
Pigment composition and colored photosensitive composition
Abstract
A colored photosensitive composition is composed of a pigment
composition, a binder polymer having an acidic group, a
multi-functional monomer having at least two ethylenic unsaturated
double bonds, and a photopolymerization initiator. The pigment
composition is composed of an organic pigment, a dispersant, and an
organic solvent. The dispersant is a copolymer of a polymerizable
oligomer having an ethylenic unsaturated double bond in its
terminal position and one or more monomers at least one of which
has a nitrogen-containing group and an ethylenic unsaturated double
bond.
Inventors: |
Takeda, Akihiko; (Shizuoka,
JP) ; Morimoto, Shinichiro; (Shizuoka, JP) ;
Yoshimura, Kousaku; (Shizuoka, JP) |
Correspondence
Address: |
NIXON PEABODY, LLP
8180 GREENSBORO DRIVE
SUITE 800
MCLEAN
VA
22102
US
|
Family ID: |
26449984 |
Appl. No.: |
09/750789 |
Filed: |
January 2, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09750789 |
Jan 2, 2001 |
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09058221 |
Apr 10, 1998 |
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6194480 |
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Current U.S.
Class: |
525/296 ;
106/31.43; 106/31.57; 106/31.75; 106/31.85; 525/259; 525/262;
525/293; 525/329.4; 525/329.7 |
Current CPC
Class: |
C09B 67/0069 20130101;
G03F 3/106 20130101; G03F 7/0007 20130101; C08F 290/046
20130101 |
Class at
Publication: |
525/296 ;
106/31.43; 106/31.57; 106/31.75; 106/31.85; 525/259; 525/293;
525/329.4; 525/329.7; 525/262 |
International
Class: |
C08F 220/56; C09D
017/00; C08F 220/06; C08F 220/54; C08F 226/02; C08F 226/06; C08F
226/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 1997 |
JP |
9-157699 |
Apr 10, 1997 |
JP |
9-110338 |
Claims
What is claimed is:
1. A pigment composition comprising an organic pigment, a
dispersant, and an organic solvent, wherein the dispersant is a
copolymer of a polymerizable oligomer having an ethylenic
unsaturated double bond in its terminal position and one or more
monomers at least one of which has a nitrogen-containing group and
an ethylenic unsaturated double bond.
2. The pigment composition of claim 1, wherein the copolymer
comprises repeating units derived from the polymerizable oligomer
in an amount of 20 to 99 wt. % of the total repeating units, and
repeating units derived from the monomer or monomers in an amount
of 1 to 40 wt. % of the total repeating units.
3. The pigment composition of claim 1, wherein the copolymer is a
copolymer of a polymerizable oligomer having an ethylenic
unsaturated double bond in its terminal position and two or more
monomers at least one of which has a nitrogen-containing group and
an ethylenic unsaturated double bond and other of which has an
ethylenic unsaturated double bond and has no nitrogen-containing
group.
4. The pigment composition of claim 1, wherein the polymerizable
oligomer is a poly(alkyl acrylate), a copolymer of an alkyl
acrylate and a copolymerizable monomer, a poly(alkyl methacrylate),
a copolymer of an alkyl methacrylate and a copolymerizable monomer,
or polystyrene, any of which has a number average molecular weight
of 1,000 to 10,000 and has an acryloyl or methacryloyl group in its
terminal position.
5. The pigment composition of claim 1, wherein the monomer having a
nitrogen-containing group and an ethylenic unsaturated double bond
is a compound of the following formula (1): 9in which R.sup.11
represents hydrogen atom or methyl group; R.sup.12 represents an
alkylene group of 1 to 8 carbon atoms; X.sup.1 represents
--N(R.sup.13)(R.sup.14) in which each of R.sup.13 and R.sup.14
independently is hydrogen atom, an alkyl group of 1 to 6 carbon
atoms, or phenyl group, --R.sup.15--N(R.sup.16)(R.- sup.17) in
which R.sup.15 is an alkylene group of 1 to 6 carbon atoms and each
of R.sup.16 and R.sup.17 independently is hydrogen atom, an alkyl
group of 1 to 6 carbon atoms, or phenyl group, or a heterocyclic
group selected from the group consisting of pyrrolidino,
pyrrolidyl, pyridyl, piperidino or morpholino; and each of m and n
independently is 0 or 1.
6. The pigment composition of claim 1, wherein the organic pigment
is an acidic yellow pigment.
7. A colored photosensitive composition which comprises a pigment
composition, a binder polymer having an acidic group, a
multi-functional monomer having at least two ethylenic unsaturated
double bonds, and a photopolymerization initiator, said pigment
composition comprising an organic pigment, a dispersant, and an
organic solvent, wherein the dispersant is a copolymer of a
polymerizable oligomer having an ethylenic unsaturated double bond
at its terminal position and one or more monomers at least one of
which has a nitrogen-containing group and an ethylenic unsaturated
double bond.
8. The colored photosensitive composition of claim 7, wherein the
copolymer comprises repeating units derived from the polymerizable
oligomer in an amount of 20 to 99 wt. % of the total repeating
units, and repeating units derived from the monomer or monomers in
an amount of 1 to 40 wt. % of the total repeating units.
9. The colored photosensitive composition of claim 7, wherein the
copolymer is a copolymer of a polymerizable oligomer having an
ethylenic unsaturated double bond in its terminal position and two
or more monomers at least one of which has a nitrogen-containing
group and an ethylenic unsaturated double bond and other of which
has an ethylenic unsaturated double bond and has no
nitrogen-containing group.
10. The colored photosensitive composition of claim 7, wherein the
polymerizable oligomer is a poly(alkyl acrylate), a copolymer of an
alkyl acrylate and a copolymerizable monomer, a poly(alkyl
methacrylate), a copolymer of an alkyl methacrylate and a
copolymerizable monomer, or polystyrene, any of which has a number
average molecular weight of 1,000 to 10,000 and has an acryloyl or
methacryloyl group in its terminal position.
11. The colored photosensitive composition of claim 7, wherein the
monomer having a nitrogen-containing group and an ethylenic
unsaturated double bond is a compound of the following formula (1):
10in which R.sup.11 represents hydrogen atom or methyl group;
R.sup.12 represents an alkylene group of 1 to 8 carbon atoms;
X.sup.1 represents --N(R.sup.13)(R.sup.14) in which each of
R.sup.13 and R.sup.14 independently is hydrogen atom, an alkyl
group of 1 to 6 carbon atoms, or phenyl group,
--R.sup.15--N(R.sup.16)(R.sup.17) in which R.sup.15 is an alkylene
group of 1 to 6 carbon atoms and each of R.sup.16 and R.sup.17
independently is hydrogen atom, an alkyl group of 1 to 6 carbon
atoms, or phenyl group, or a heterocyclic group selected from the
group consisting of pyrrolidino, pyrrolidyl, pyridyl, piperidino or
morpholino; and each of m and n independently is 0 or 1.
12. The colored photosensitive composition of claim 7, wherein the
organic pigment is an acidic yellow pigment.
13. A copolymer of a polymerizable oligomer and one or more
monomers wherein the polymerizable oligomer is selected from the
group consisting of a poly(alkyl acrylate), a copolymer of an alkyl
acrylate and a copolymerizable monomer, a poly(alkyl methacrylate),
a copolymer of an alkyl methacrylate and a copolymerizable monomer,
or polystyrene, any of which has a number average molecular weight
of 1,000 to 10,000 and has an acryloyl or methacryloyl group in its
terminal position; and at least one monomer is a compound of the
following formula (1): 11in which R.sup.11 represents hydrogen atom
or methyl group; R.sup.12 represents an alkylene group of 1 to 8
carbon atoms; X.sup.1 represents --N(R.sup.13)(R.sup.14) in which
each of R.sup.13 and R.sup.14 independently is hydrogen atom, an
alkyl group of 1 to 6 carbon atoms, or phenyl group,
--R.sup.15--N(R.sup.16)(R.sup.17) in which R.sup.15 is an alkylene
group of 1 to 6 carbon atoms and each of R.sup.16 and R.sup.17
independently is hydrogen atom, an alkyl group of 1 to 6 carbon
atoms, or phenyl group, or a heterocyclic group selected from the
group consisting of pyrrolidino, pyrrolidyl, pyridyl, piperidino or
morpholino; and each of m and n independently is 0 or 1.
14. The copolymer of claim 13, wherein the copolymer comprises
repeating units derived from the polymerizable oligomer in an
amount of 20 to 99 wt. % of the total repeating units, and
repeating units derived from the one or more monomers in an amount
of 1 to 40 wt. % of the total repeating units.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a novel copolymer which is
advantageously employable as a dispersant for dispersing a pigment
in a solvent or a binder solution. The invention further relates a
pigment-dispersing composition and a colored photosensitive
composition which show good pigment-dispersibility, good fluidity
and good coloring power. The pigment composition and the colored
photosensitive composition of the invention are advantageously
employable as coating materials, printing inks and materials for
manufacturing color display units. Particularly, the colored
photosensitive composition is favorably employable for forming a
multi-color image on a substrate (e.g., color proof) and for
preparing a color filter of a liquid crystal color display
unit.
BACKGROUND OF THE INVENTION
[0002] A practically important pigment, which shows bright color
tone and has high coloring power, generally is in the form of very
fine particles. If the particle size is made to be much smaller so
as to enhance the coloring power, however, the pigment dispersion
liquid often exhibits such high viscosity that some troubles are
apt to be caused in its industrial production process, that is, the
dispersion liquid may hardly flow out of a dispersing apparatus,
and it sometimes is impossible to transport the dispersion liquid
through pipe lines. Further, the pigment dispersion liquid having
such high viscosity may turn into gel in the course of storage.
[0003] A colored photosensitive composition containing the pigment
is useful, for instance, as an image-forming material for producing
color proofs or color filters. The pigment contained in the colored
photosensitive composition is required to exhibit bright color tone
and to show high coloring power.
[0004] In the process for forming a color image using the colored
photosensitive composition, the composition is coated on a
substrate to form a colored photosensitive layer, and then exposed
through a predetermined pattern and developed. As the developer
used in the developing procedure, an aqueous alkaline solution is
more frequently employed than an organic solvent in consideration
of environmental preservation. Hence, the unexposed photo-sensitive
layer is required to be soluble in the aqueous alkaline solution.
On the other hand, an organic solvent is advantageously used as a
solvent (i.e., dispersing medium) of the coating liquid containing
the colored photosensitive composition because the coating liquid
in the organic solvent is easily dried. Therefore, a binder
contained in the composition is generally required not only to have
an acidic group but also to be soluble in an appropriate organic
solvent, and in fact the conventional colored photosensitive
composition comprises organic pigment particles dispersed in the
binder having an acidic group.
[0005] Since the layer of a colored photosensitive composition is
generally required to be very thin and to have high coloring power,
the organic pigment must be very finely dispersed in the binder
(which has an acidic group and further which is soluble in an
organic solvent).
[0006] As described hereinbefore, the colored photosensitive
composition (i.e., a pigment dispersed photosensitive composition)
is useful, for example, as a material for forming a color filter of
a liquid crystal display unit.
[0007] The color filter comprises red, green, and blue colorants on
a transparent substrate in the positions of respective pixels so
that light can selectively pass through the pixels to display the
desired color image. In the process for producing the filter, the
colorants are placed on the substrate by various methods such as
dyeing method, printing method, electrodeposition method, and
pigment dispersion method. The pigment dispersion method is most
preferred because the production process is reliable and it gives a
color filter of high quality.
[0008] The pigment dispersion method comprises the steps of coating
the transparent substrate with the colored photosensitive liquid
composition containing the pigment composition to form a colored
photosensitive layer; pattern-wise exposing the layer; developing
in a developing solution the layer to form a pixel pattern of the
first color, and then repeating those steps for each color to
prepare a plural number of color image patterns each consisting of
a large number of pixels. Since the colorant is a solid pigment in
the form of fine particles (which is insoluble in ordinary solvents
such as organic solvents) in this method, the pigment particles may
scatter or absorb the applied light to lower the transparency of
the filter if the particle size is large. Further, in that case,
the axis of polarized light may be rotated by scattering and/or
birefringence, and consequently the contrast of an image given by
the liquid crystal display unit may lower (ref., "Seventh Color
Optics Conference (1990)", a color filter for 10.4" size TFT-LCD
display of 512 colors, Ueki, Koseki, Fukunaga and Yamanaka). Hence,
the pigment particles are desired to be dispersed finely and
uniformly enough and it is requried for the particle size to be
appropriately small.
[0009] In order to make the pigment particles well dispersed and to
give good fluidity to the pigment dispersion liquid, various kinds
of dispersants are developed. Generally used dispersants can be
roughly classified into two types, namely, a polymer type and a low
molecular weight type. Examples of the polymer type dispersants
include polyacrylate, sodium maleate-olefin copolymer, polyester
having carboxyl terminal (Japanese Patent Publication No.
54-34009), a polyester having an acidic group and/or basic group
derived from tetrakis(2-hydroxyalkyl)e- thylenediamine (Japanese
Patent Provisional Publication No. H2-245231), and a copolymer
derived from the following four kinds of monomer, namely, a
macromonomer (i.e., an oligomer having an ethylenic unsaturated
group in its terminal position), a monomer having a hydroxyl group,
a monomer having a carboxyl group and other monomer (Japanese
Patent Provisional Publication No. H8-259876). Examples of the low
molecular weight type dispersants include a sorbitan fatty acid
ester, a polyoxyethylenealkylamine, an alkyldiamine and an alkanol
amine derivative (U.S. Pat. No. 3,536,510).
[0010] The copolymer derived from a macromonomer and others is said
to be useful for preparing a colored photosensitive composition for
color filter or color proof. Japanese Patent Provisional
Publication No. H8-259876 discloses that the above-mentioned
copolymer (which is derived from a macromonomer and others) makes
the pigment particle size small enough and improves dispersing
stability.
[0011] The present inventors have examined known colored
photosensitive compositions and found that there are the following
problems in the known compositions. In the case that organic
pigment particles are dispersed in the binder which has an acidic
group and is soluble in an organic solvent, the dispersion liquid
is apt to show a high viscosity because of certain intermolecular
interaction between the acidic group and the organic pigment
particle. The viscous dispersion liquid is not preferred in
consideration of dispersion of the pigment particles although the
dispersion stability is enhanced, and hence more appropriate
dispersant is needed so as to control the viscosity and to promote
good dispersion of the particles. Among the above-described known
lower molecular weight type dispersants, amine compounds are found
to be relatively effective to promote the dispersion. However,
since the amine compound easily reacts with the acidic group of the
binder to form a salt, it sometimes causes some troubles in the
developing procedure (for example, the photosensitive resin layer
may turns to show less solubility in an aqueous alkaline developing
solution). Further, it has been found that the known water-soluble
dispersants and various alkaline dispersants have the same problem
as the above-mentioned amine compound.
SUMMARY OF THE INVENTION
[0012] The inventors have further examined the dispersant which is
the copolymer derived from four kinds of reactive compounds, that
is, a macromonomer (which is an oligomer having an ethylenic
unsaturated group at the terminal position), a monomer having
hydroxyl group, a monomer having carboxyl group and other
monomer(s) (Japanese Patent Provisional Publication No. H8-259876).
In the case using the above-mentioned copolymer, the obtained
dispersion liquid is not as viscous as that employing a known
polymer type dispersant. However, the copolymer does not
satisfactory promote dispersion of the fine particles, and
consequently the particles are apt to be insufficiently dispersed
in the liquid. The inventors have studied why the viscosity
increase is relatively low when this copolymer is employed, and
concluded that certain steric hindrance of the polymer chain
derived from the macromonomer favorably works to keep the viscosity
at a raltively low level. As a result, the inventors have produced
a variety of copolymers using the macromonomer and other monomers
and studied their characteristics as dispersants.
[0013] It is an object of the present invention to provide a
pigment dispersion composition having excellent characteristics
such as good dispersion stability, good fluidity, high
transparency, and good coloring power.
[0014] It is another object of the invention to provide a colored
photosensitive composition which shows a high coloring power and is
hardly disturbed in the developing step using an aqueous alkaline
developing solution.
[0015] Furthermore, it is an object of the invention to provide a
new copolymer which makes pigment particles finely dispersed in a
binder polymer solution and which gives improved stability to the
finely dispersed particles.
[0016] The present invention resides in a pigment composition
comprising an organic pigment, a dispersant, and an organic
solvent, wherein the dispersant is a copolymer of a polymerizable
oligomer having an ethylenic unsaturated double bond in its
terminal position and one or more monomers at least one of which
has a nitrogen-containing group and an ethylenic unsaturated double
bond.
[0017] In the pigment composition of the invention, preferred are
the following embodiments:
[0018] 1) The copolymer comprises repeating units derived from the
polymerizable oligomer in an amount of 20 to 99 wt. % (based on the
total repeating units), and repeating units derived from the
monomer or monomers in an amount of 1 to 40 wt. % (based on the
total repeating units).
[0019] 2) The copolymer is a copolymer of a polymerizable oligomer
having an ethylenic unsaturated double bond in its terminal
position and two or more monomers at least one of which has both a
nitrogen-containing group and an ethylenic unsaturated double bond
and other of which has an ethylenic unsaturated double bond but
having no nitrogen-containing group.
[0020] 3) The polymerizable oligomer is a poly(alkyl acrylate), a
copolymer of alkyl acrylate and a copolymerizable monomer, a
poly(alkyl methacrylate), a copolymer of an alkyl methacrylate and
a copolymerizable monomer, or polystyrene, any of which has a
number average molecular weight of 1,000 to 10,000 and has an
acryloyl or methacryloyl group in its terminal position.
[0021] 4) The monomer having a nitrogen-containing group and an
ethylenic unsaturated double bond is a compound of the following
formula (1): 1
[0022] in which
[0023] R.sup.11 represents hydrogen atom or methyl group;
[0024] R.sup.12 represents an alkylene group of 1 to 8 carbon
atoms;
[0025] X.sup.1 represents --N(R.sup.13) (R.sup.14) in which each of
R.sup.13 and R.sup.14 independently is hydrogen atom, an alkyl
group of 1 to 6 carbon atoms, or phenyl group;
--R.sup.15--N(R.sup.16)(R.sup.17) in which R.sup.15 is an alkylene
group of 1 to 6 carbon atoms and each of R.sup.16 and R.sup.17
independently represents hydrogen atom, an alkyl group of 1 to 6
carbon atoms, or phenyl group; or a heterocyclic group such as
pyrrolidino group, pyrrolidyl group, pyridyl group, piperidino
group, or morpholino group; and
[0026] each of m and n independently represents 0 or 1.
[0027] 5) The monomer having a nitrogen-containing group and an
ethylenic unsaturated double bond is a compound of the following
formula (2): 2
[0028] in which R.sup.21, R.sup.22 and X.sup.2 have the same
meaning as R.sup.11, R.sup.12 and X.sup.1 of the formula (1),
respectively.
[0029] 6) The monomer having a nitrogen-containing group and an
ethylenic unsaturated double bond is a compound of the following
formula (3): 3
[0030] in which R.sup.31 and X.sup.3 have the same meaning as
R.sup.11 and X.sup.1 of the formula (1), respectively (X.sup.3
preferably represents --N(R.sup.33) (R.sup.34) in which R.sup.33
and R.sup.34 have the same meansing as R.sup.13 and R.sup.14 of the
formula (1), respectively; and also X.sup.3 preferably represents
--R.sup.35--N(R.sup.36) (R.sup.37) in which R.sup.35 R.sup.36 and
R.sup.37 have the same meaning as R.sup.15, R.sup.16 and R.sup.17
of the formula (1), respectively.
[0031] 7) The monomer having a nitrogen-containing group and an
ethylenic unsaturated double bond is a compound of the following
formula (4): 4
[0032] in which R.sup.41 has the same meaning as R.sup.11 of the
formula (1); and X.sup.4 is pyrrolidino group, pyrrolidyl group,
pyridyl group, piperidino group, or morpholino group.
[0033] 8) The pigment composition further comprises a binder
polymer having an acidic group.
[0034] 9) The organic pigment is a yellow pigment.
[0035] 10) The organic pigment has an acidic group.
[0036] The present invention also resides in a colored
photosensitive composition which comprises a pigment composition, a
binder polymer having an acidic group, a multi-functional monomer
having at least two ethylenic unsaturated double bonds, and a
photopolymerization initiator, in which the pigment composition
comprises an organic pigment, a dispersant, and an organic solvent,
wherein the dispersant is a copolymer of a polymerizable oligomer
having an ethylenic unsaturated double bond in its terminal
position and one or more monomers at least one of which has a
nitrogen-containing group and an ethylenic unsaturated double
bond.
[0037] The invention further resides in a novel copolymer of a
polymerizable oligomer and one or more monomers wherein the
polymerizable oligomer is a poly(alkyl acrylate), a copolymer of an
alkyl acrylate and a copolymerizable monomer, a poly(alkyl
methacrylate), a copolymer of an alkyl methacrylate and a
copolymerizable monomer, or polystyrene, any of which has a number
average molecular weight of 1,000 to 10,000 and has an acryloyl or
methacryloyl group in its terminal position;
[0038] and
[0039] at least one monomer is a compound of the following formula
(1): 5
[0040] in which
[0041] R.sup.11 is hydrogen atom or methyl group;
[0042] R.sup.12 is an alkylene group of 1 to 8 carbon atoms;
[0043] X.sup.1 is --N(R.sup.13) (R.sup.14) in which each of
R.sup.13 and R.sup.14 independently is hydrogen atom, an alkyl
group of 1 to 6 carbon atoms, or phenyl group;
--R.sup.15--N(R.sup.16) (R.sup.17) in which R.sup.15 is an alkylene
group of 1 to 6 carbon atoms and each of R.sup.16 and R.sup.17
independently represents hydrogen atom, an alkyl group of 1 to 6
carbon atoms, or phenyl group; or a heterocyclic group such as
pyrrolidino group, pyrrolidyl group, pyridyl group, piperidino
group, or morpholino group; and
[0044] each of m and n independently represents 0 or 1.
[0045] The copolymer preferably comprises repeating units derived
from the polymerizable oligomer in an amount of 20 to 99 wt. % of
the total repeating units, and repeating units derived from the one
or more monomers in an amount of 1 to 40 wt. % of the total
repeating units.
[0046] The polymerizable oligomer preferably has a number average
molecular weight of 2,000 to 9,000, and the copolymer preferably
has a weight average molecular weight of 3,000 to 100,000.
[0047] The polymerizable oligomer preferably is a polymer
represented by the following formula (5): 6
[0048] in which each of R.sup.51 and R.sup.53 independently
represents hydrogen atom or methyl group; R.sup.52 is an alkylene
group of 1 to 8 (preferably, 2 to 4) carbon atoms; Y represents
phenyl group or a phenylalkyl group whose alkyl group has 1 to 4
carbon atoms; or Y represents --COOR.sup.54 in which R.sup.54 is an
alkyl group of 1 to 6 carbon atoms, phenyl group or an arylalkyl
group of 7 to 10 carbon atoms; and q is an integer of 20 to
200.
[0049] The colored photosensitive composition is advantageously
employable for performing a image forming method comprising the
steps of coating a substrate with the organic solution of the
composition; drying the coated solution to form a colored
photosensitive layer; making the layer imagewise exposed, and then
developed. Further, it can be also advantageously employed for the
image forming method comprising the steps of preparing the
photosensitive image transfer sheet having a layer of the
photosensitive composition thereon; transferring the layer of the
photosensitive composition onto a substrate; making the transferred
layer imagewise exposed, and then developed. In those processes, a
colored photosensitive composition can be advantageously employed
for preparing color filters or color proofs.
BRIEF DESCRIPTION OF DRAWINGS
[0050] FIG. 1 is a schematic view showing a structure of the
copolymer of the invention.
[0051] FIG. 2 is a schematic view showing the copolymer of the
invention adsorbed on the surface of a pigment particle.
DETAILED DESCRIPTION OF THE INVENTION
[0052] The pigment-dispersing composition of the invention
comprises an organic solvent, an organic pigment, and a copolymer
derived from a polymerizable oligomer having an ethylenic
unsaturated double bond at its terminal (hereinafter, the
polymerizable oligomer is referred to as "macromonomer") and a
monomer having a nitrogen-containing group as well as an ethylenic
unsaturated double bond. In addition to the pigment dispersion
composition, the colored photosensitive composition of the
invention further comprises a binder polymer having an acidic
group, a multi-functional monomer having at least two ethylenic
unsaturated double bonds, and a photopolymerization initiator.
[0053] The above-mentioned copolymer can be produced by
copolymerization reaction between the ethylenic unsaturated double
bond at the terminal of the macromonomer and the double bond of the
monomer having a nitrogen-containing group, and hence the copolymer
has the structure, for example, shown in FIG. 1.
[0054] In FIG. 1, the numeral 1 indicates a part corresponding to
the ethylenic unsaturated double bond of the macromonomer
(ethylenic unsaturated double bond is changed to a single bond in
the course of copolymerization, and hence 1 is a single bond). The
numeral 2 indicates a polymer chain of the macromonomer connecting
to the numeral 1. The numeral 3 indicates the monomer unit derived
from the monomer having a nitrogen-containing group, and is formed
by copolymerization between the macromonomer and the monomer.
[0055] FIG. 2 schematically shows the copolymer attached to a
pigment particle. The nitrogen atom in the nitrogen-containing
group of each monomer unit 3 is attached to the surface of the
organic pigment particle 4, and the polymer chains 2 of the
macromonomers are stuck out of the surface to cover the particle
4.
[0056] As described above, in the case that the pigment-dispersing
composition is used for the preparation of a photosensitive
composition, the acidic group contained in the binder polymer and
the nitrogen-containing group often interact strongly with each
other or react with each other to form a salt. However, the polymer
chains 2 inhibit this undesirable behavior, improve the dispersion
stability, and enhance the dispersibility by the aid of the
nitrogen-containing group. Consequently, the copolymer of the
invention raises the viscosity at only a small degree while a known
polymer-type dispersant having a nitrogen-containing group often
makes the dispersion liquid too viscous, and further the copolymer
of the invention promotes the dispersion of the organic pigment
particles in the binder solution. Particularly, it remarkably
enhances the dispersion of an acidic organic pigment such as a
yellow pigment.
[0057] The polymerizable oligomer having an ethylenic unsaturated
double bond in its terminal position (namely, macromonomer)
consists essentially of a polymer chain and the group having the
ethylenic unsaturated double bond at the terminal of the chain.
Preferably, the macromonomer has the group having the ethylenic
unsaturated double bond at only one of the terminals of the polymer
chain. The polymerizable oligomer preferably has a number average
molecular weight Mn (converted to that of polystyrene) of 1,000 to
10,000, more preferably 2,000 to 9,000.
[0058] The above polymer chain is generally a homopolymer or a
copolymer derived from at least one selected from the group
consisting of an alkyl (meth)acrylate, styrene, acrylonitrile,
vinyl acetate, and butadiene. Preferred is a homopolymer or a
copolymer derived from an alkyl acrylate, an alkyl methacrylate
and/or polystyrene.
[0059] Preferred examples of the groups having the ethylenic
unsaturated double bond include (meth)acryloyl group and vinyl
group. Particularly preferred is acryloyl or methacryloyl
group.
[0060] Preferably, the above polymerizable oligomer is an oligomer
represented by the following formula (5): 7
[0061] in which each of R.sup.51 and R.sup.53 independently
represents hydrogen atom or methyl group; R.sup.52 is an alkylene
group of 1 to 8 (preferably 2 to 4, more preferably 2) carbon
atoms; Y represents phenyl group or a phenylalkyl group whose alkyl
group has 1 to 4 carbon atoms; or Y represents --COOR.sup.54 in
which R.sup.54 is an alkyl group of 1 to 6 carbon atoms, phenyl
group or an arylalkyl group of 7 to 10 carbon atoms; and q is an
integer of 20-200. Preferably, Y represents phenyl group or
--COOR.sup.54 in which R.sup.54 is an alkyl group of 1 to 4 carbon
atoms.
[0062] Preferred examples of the polymerizable oligomers (i.e.,
macromonomers) include styrene polymer, polymethyl (meth)acrylate,
poly-n-butyl (meth)acrylate, and polyisobutyl (meth)acrylate, each
of which has (meth)acryloyl group in one terminal position.
Examples of the commercially available polymerizable oligomers
include a polystyrene oligomer having methacryloyl group in one
terminal position (Mn: 6,000; AS-6 (trade name), available from Toa
Gosei Kagaku Kogyo Co., Ltd.), polymethyl methacrylate oligomer
having methacryloyl group in one terminal position (Mn: 6,000; AA-6
(trade name), available from Toa Gosei Kagaku Kogyo Co., Ltd.), and
poly-n-butyl acrylate oligomer having methacryloyl group in one
terminal position (Mn: 6,000; AB-6 (trade name), available from Toa
Gosei Kagaku Kogyo Co., Ltd.).
[0063] Preferably, the above monomer having a nitrogen-containing
group and an ethylenic unsaturated double bond is a compound of the
aforementioned formula (1).
[0064] More preferably, the above monomer is a compound of any of
the aforementioned formulas (2) to (4).
[0065] In the formula, the following is preferred.
[0066] R.sup.12 is an alkylene group of 1-6 (more preferably 2-3)
carbon atoms; X.sup.1 is --N(R.sup.13) (R.sup.14) in which each of
R.sup.13 and R.sup.14 independently represents hydrogen atom, an
alkyl group of 1-4 carbon atoms, or phenyl group; or X.sup.1
represents --R.sup.15--N(R.sup.16)(R.sup.17) in which R.sup.15 is
an alkylene group of 2-6 carbon atoms and each of R.sup.16 and
R.sup.17 independently represents an alkyl group of 1-4 carbon
atoms; or X.sup.1 is pyrrolidino group, pyrrolidyl group
(particularly, 2-pyrrolidyl group), pyridyl group (particularly,
1-pyridyl group, 2-pyridyl group), piperidino group (particularly,
1-piperidino group), or morpholino group (particularly,
4-morpholino group).
[0067] Particularly preferred monomers are compounds of the
formulas (2) and (3), which correspond to the case of m=1 and n=1
and the case of m=1 and n=0 in the formula (1), respectively.
[0068] Preferred examples of the compounds of the formula (1)
include (meth)acrylates such as N,N-dimethylaminoethyl
(meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate,
1-(N,N-dimethylamino)-1,1-dimethy- lmethyl (meth)acrylate,
N,N-dimethylaminohexyl (meth)acrylate, N,N-diethylaminoethyl
(meth)acrylate, N,N-diisopropylaminoethyl (meth)acrylate,
N,N-di-n-butylaminoethyl (meth)acrylate, N,N-di-isobutylaminoethyl
(meth)acrylate, morpholinoethyl (meth)acrylate, piperidinoethyl
(meth)acrylate, 1-pyrrolidinoethyl (meth)acrylate,
N,N-methyl-2-pyrrolidylaminoethyl (meth)acrylate, and
N,N-methylphenylaminoethyl (meth)acrylate; (meth)acrylamides such
as dimethyl (meth)acrylamide, diethyl (meth)acrylamide, diisopropyl
(meth)acrylamide, di-n-butyl (meth)acrylamide, diisobutyl
(meth)acrylamide, morpholino (meth)acrylamide, piperidino
(meth)acrylamide, N-methyl-2-pyrrolidyl (meth)acrylamide and
N,N-methylphenyl (meth)acrylamide; aminoalkyl (meth)acrylamides
such as 2-(N,N-dimethylamino)ethyl (meth)acrylamide,
2-(N,N-diethylamino)ethyl (meth)acrylamide,
3-(N,N-diethylamino)propyl (meth)acrylamide,
3-(N,N-dimethylamino)propyl (meth)acrylamide,
1-(N,N-dimethylamino)-1,1-d- imethylmethyl (meth)acrylamide, and
6-(N,N-diethylamino)hexyl (meth)acrylamide; and vinylpyridine.
[0069] It is also preferred that the copolymer of the invention is
derived from the above-mentioned polymerizable oligomer, the above
monomer, and another monomer copolymerizable with them. Examples of
the monomers copolymerizable with the above-mentioned oligomer and
monomer include unsaturated carboxylic acid (e.g., (meth)acrylic
acid, crotonic acid, itaconic acid, maleic acid and fumaric acid);
aromatic vinyl compound (e.g., styrene, .alpha.-methylstyrene and
vinyltoluene); (meth)acrylic acid alkyl ester (e.g., methyl
(meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate and
isobutyl (meth)acrylate); (meth)acrylic acid alkylaryl ester (e.g.,
benzyl (meth)acrylate); glycidyl (meth)acrylate; carboxylic acid
vinyl ester (e.g., vinyl acetate and vinyl propionate); vinyl
cyanide (e.g., (meth)acrylonitrile and
.alpha.-chloroacrylonitrile)- ; and aliphatic conjugated diene
(e.g., 1,3-butadiene and isoprene). Among the above monomers,
unsaturated carboxylic acid, (meth)acrylic acid alkyl ester,
(meth)acrylic acid alkylaryl ester and carboxylic acid vinyl ester
are preferred.
[0070] The copolymer of the invention can be derived from the
above-mentioned polymerizable oligomer (macromonomer) and the
above-mentioned monomer having a nitrogen-containing group.
Further, the copolymer of the invention may be also derived from
the polymerizable oligomer, the monomer having a
nitrogen-containing group, and the monomer having no
nitrogen-containing group but having an ethylenic unsaturated
double bond with which the monomer can be copolymerized with the
above-mentioned oligomer (i.e., macromonomer) and monomer (which
has a nitrogen-containing group).
[0071] The copolymer preferably comprises repeating units derived
from the polymerizable oligomer in an amount of 20 to 99 wt. %
(particularly 20 to 80 wt. %) of the total repeating units, and
repeating units derived from the monomer having a
nitrogen-containing group in an amount of 1 to 40 wt. %
(particularly 5 to 30 wt. %) of the total repeating units. In the
case that the copolymer is derived from the above-mentioned
oligomer, the monomer having a nitrogen-containing group and the
monomer copolymerizable with them, the copolymer preferably
comprises repeating units derived from the copolymerizable monomer
in an amount of 5 to 70 wt. % of the total repeating units.
[0072] The copolymer preferably has a weight average molecular
weight (Mw) of 3,000 to 100,000 (more preferably, 5,000 to 50,000,
in terms of Mw of polystyrene). The weight average molecular weight
here is a value converted to that of polystyrene, and is determined
by means of gel permeation chromatography (carrier:
tetrahydrofuran).
[0073] Concrete examples of the copolymer are as follows:
[0074] (1) copolymer of dimethylaminoethyl acrylate/poly(methyl
methacrylate) having methacryloyl terminal,
[0075] (2) copolymer of diethylaminoethyl acrylate/poly(methyl
methacrylate) having methacryloyl terminal,
[0076] (3) copolymer of di-n-butylaminoethyl acrylate/poly(methyl
methacrylate) having methacryloyl terminal,
[0077] (4) copolymer of di-isobutylaminoethyl acrylate/poly(methyl
methacrylate) having methacryloyl terminal,
[0078] (5) copolymer of dimethylaminoethyl acrylate/polystyrene
having methacryloyl terminal,
[0079] (6) copolymer of dimethylaminoethyl acrylate/poly(methyl
methacrylate) having methacryloyl terminal/benzyl methacrylate,
[0080] (7) copolymer of diethylaminoethyl acrylate/poly(methyl
methacrylate) having methacryloyl terminal/benzyl methacrylate,
[0081] (8) copolymer of di-n-butylaminoethyl acrylate/poly(methyl
methacrylate) having methacryloyl terminal/benzyl methacrylate,
[0082] (9) copolymer of di-isobutylaminoethyl acrylate/poly(methyl
methacrylate) having methacryloyl terminal/benzyl methacrylate,
[0083] (10) copolymer of vinylpyridine/poly(methyl methacrylate)
having methacryloyl terminal/benzyl methacrylate,
[0084] (11) copolymer of N,N-methyl-2-piperidylethyl
acrylate/poly(methyl methacrylate) having methacryloyl
terminal/benzyl methacrylate,
[0085] (12) copolymer of 1-piperidinoethyl acrylate/poly(methyl
methacrylate) having methacryloyl terminal/benzyl methacrylate,
[0086] (13) copolymer of N,N-methylphenylaminoethyl
acrylate/poly(methyl methacrylate) having methacryloyl
terminal/benzyl methacrylate,
[0087] (14) copolymer of 4-morpholinoethyl acrylate/poly(methyl
methacrylate) having methacryloyl terminal/benzyl methacrylate,
[0088] (15) copolymer of dimethylaminoethyl acrylate/polystyrene
having methacryloyl terminal/benzyl methacrylate,
[0089] (16) copolymer of dimethylaminoethyl acrylate/polystyrene
having methacryloyl terminal/methyl methacrylate,
[0090] (17) copolymer of dimethylaminoethyl acrylate/polystyrene
having methacryloyl terminal/styrene,
[0091] (18) copolymer of 3-(N,N-dimethylamino)propyl
acrylamide/poly(methyl methacrylate) having methacryloyl
terminal,
[0092] (19) copolymer of 3-(N,N-dimethylamino)propyl
acrylamide/polystyrene having methacryloyl terminal
[0093] (20) copolymer of 2-(N,N-dimethylamino)ethyl
acrylamide/poly(methyl methacrylate) having methacryloyl
terminal,
[0094] (21) copolymer of 2-(N,N-diethylamino)ethyl
acrylamide/poly(methyl methacrylate) having methacryloyl
terminal.
[0095] The copolymer can be formed by radical polymerization of the
polymerizable oligomer, the monomer having a nitrogen-containing
group, and optionally one or more other monomers copolymerizable
with them. For the polymerization reaction in a solvent, a radical
polymerization initiator is generally employed, and optionally a
chain transfer agent (e.g., 2-mercaptoethanol and dodecylmercaptan)
is also employed.
[0096] Synthesis examples of the copolymers of the invention are
shown below.
Synthesis Example 1
[0097] Fifteen weight parts of 1-methoxy-2-propyl acetate was
placed in a three-necked distillation flask in nitrogen gas
atmosphere. Under stirring by a three-one motor, the flask was
heated to 78.degree. C. in a stream of nitrogen gas.
[0098] Each of the monomer solution and the initiator solution
consisting of the following components was independently prepared,
and then the solutions were simultaneously placed dropwise to the
flask for 135 minutes.
1 (Components of monomer solution) Dimethylaminoethyl acrylate 4.1
weight parts Poly(methyl methacrylate) having 25.9 weight parts
methacryloyl group at one terminal [number average molecular
weight: 6,000, MACROMONOMER AA-6 (trade name), available from Toa
Gosei Kagaku Kogyo Co., Ltd.] 1-Methoxy-2-propyl acetate 45 weight
parts (Components of initiator solution) 2,2-Azobis
(2,4-dimethylvaleronitrile) 0.04 weight part [V-65 (trade name),
available from Wako Junyaku Co., Ltd.] 1-Methoxy-2-propyl acetate
9.6 weight parts
[0099] Subsequently, 0.08 weight part of
2,2-azobis(2,4-dimethylvaleronitr- ile) [V-65, trade name] was
placed in the flask. The flask was kept at 78.degree. C. for 3
hours, and then heated to 90.degree. C. and kept the temperature
for 30 minutes. After that, the flask was cooled to room
temperature to obtain a polymer solution. The obtained polymer
solution contained a solid content of 30 wt. %, and the
polymerization yield was 98%. The weight average molecular weight
of the prepared copolymer was measured by means of gel permeation
chromatography (C-R.sup.4A, Shimadzu Seisakusho Ltd.) and found to
be 20,000.
Synthesis Example 2
[0100] 13.4 Weight parts of 1-methoxy-2-propyl acetate were placed
in a three-necked distillation flask in nitrogen gas atmosphere.
Under stirring by a three-one motor, the flask was heated to
78.degree. C. in a stream of nitrogen gas.
[0101] Each of the monomer solution and the initiator solution
consisting of the following components was independently prepared,
and then the solutions were simultaneously placed dropwise in the
flask for 135 minutes.
2 (Components of monomer solution) Dimethylaminoethyl acrylate 3.1
weight parts Benzyl methacrylate 17.2 weight parts Poly(methyl
methacrylate) having 9.3 weight parts methacryloyl group at one
terminal [number average molecular weight: 6,000, MACROMONOMER AA-6
(trade name), available from Toa Gosei Kagaku Kogyo Co., Ltd.]
1-Methoxy-2-propylacetate 45 weight parts (Components of initiator
solution) 2,2-Azobis(2,4-dimethylvaleronitrile) 0.16 weight part
[V-65 (trade name), available from Wako Junyaku Co., Ltd.]
1-Methoxy-2-propyl acetate 7.2 weight parts
[0102] Subsequently, 0.32 weight part of
2,2-azobis(2,4-dimethylvaleronitr- ile) [V-65, trade name] was
placed in the flask. The flask was kept at 78.degree. C. for 3
hours, and then heated to 90.degree. C. and kept the temperature
for 30 minutes. After that, the flask was cooled to room
temperature to obtain a polymer solution. The obtained polymer
solution contained a solid content of 30 wt. % and the
polymerization yield was 98%. The weight average molecular weight
of the prepared copolymer was measured by means of gel permeation
chromatography (C-R.sup.4A, Shimadzu Seisakusho Ltd.) and found to
be 20,000.
Synthesis Example 3
[0103] 15.5 Weight parts of 1-methoxy-2-propyl acetate were placed
in a three neck distillation flask under nitrogen gas atmosphere.
Under stirring by a three-one motor, the flask was heated to
78.degree. C. in a stream of nitrogen gas.
[0104] Each of the monomer solution and the initiator solution
consisting of the following components was independently prepared,
and then the solutions were simultaneously placed dropwise in the
flask for 135 minutes.
3 (Components of monomer solution) Dimethylaminoethyl acrylamide
4.4 weight parts Poly(methyl methacrylate) having 25.6 weight parts
methacryloyl group at one terminal [number average molecular
weight: 6,000, MACROMONOMER AA-6 (trade name), available from Toa
Gosei Kagaka Kogyo Co., Ltd.] 1-Methoxy-2-propyl acetate 45 weight
parts (Components of initiator solution)
2,2-Azobis(2,4-dimethylvaleronitrile) 0.04 weight part [V-65 (trade
name), available from Wako Junyaku Co., Ltd.] 1-Methoxy-2-propyl
acetate 9.5 weight parts
[0105] Subsequently, 0.08 weight part of
2,2-azobis(2,4-dimethylvaleronitr- ile) [V-65 (trade name)] was
placed in the flask. The flask was kept at 78.degree. C. for 3
hours, and then heated to 90.degree. C. and kept the temperature
for 30 minutes. After that, the flask was cooled to room
temperature to obtain a polymer solution. The obtained polymer
solution contained a solid content of 30 wt. % and the
polymerization yield was 98%. The weight average molecular weight
of the prepared copolymer was measured by gel permeation
chromatography (C-R4A, Shimadzu Seisakusho Ltd.) and found to be
20,000.
Synthesis Example 4
[0106] 15.5 Weight parts of 1-methoxy-2-propyl acetate were placed
in a three neck distillation flask in nitrogen gas atmosphere.
Under stirring by a three-one motor, the flask was heated to
78.degree. C. in a stream of nitrogen gas.
[0107] Each of the monomer solution and the initiator solution
consisting of the following components was independently prepared,
and then the solutions were simultaneously placed dropwise in the
flask for 135 minutes.
4 (Components of monomer solution) 3-(N,N-Dimethylamino)propyl
acrylamide 4.1 weight parts Poly(methyl methacrylate) having 25.9
weight parts methacryloyl group at one terminal [number average
molecular weight: 6,000, MACROMONOMER AA-6 (trade name), available
from Toa Gosei Kagaku Kogyo Co., Ltd.] 1-Methoxy-2-propyl acetate
45 weight parts (Components of initiator solution)
2,2-Azobis(2,4-dimethylvaleronitrile) [V-65 (trade name), available
from Wako Junyaku Co., Ltd.] 0.04 weight part 1-Methoxy-2-propyl
acetate 9.5 weight parts
[0108] Subsequently, 0.08 weight part of
2,2-azobis(2,4-dimethylvaleronitr- ile) [V-65, trade name] was
placed in the flask. The flask was kept at 78.degree. C. for 3
hours, and then heated to 90.degree. C. and kept the temperature
for 30 minutes. After that, the flask was cooled to room
temperature to obtain a polymer solution. The obtained polymer
solution contained a solid content of 30 wt. % and the
polymerization yield was 98%. The weight average molecular weight
of the prepared copolymer was measured by gel permeation
chromatography (C-R.sup.4A, Shimadzu Seisakusho Ltd.) and found to
be 20,000.
[0109] The copolymer (polymer dispersant) of the invention can be
used singly or in combination with one or more of other known
dispersants. When the copolymer is used with other dispersants, a
weight ratio of the copolymer/known dispersants is generally in the
range of 99/1 to 10/90, preferably 99/1 to 30/70. Examples of the
known dispersants include amide compounds such as nonanoamide,
decaneamide, dodecaneamide, N-dodecylhexadecaneamide,
N-octadecylpropionamide, N,N-dimethyldodecaneamide, and
N,N-dihexylacetamide; amine compounds such as diethylamine,
diheptylamine, dibutylhexadecylamine,
N,N,N',N'-tetramethylmethaneamine, triethylamine, tributylamine and
trioctylamine; amine compounds having hydroxyl group such as
monoethanolamine, diethanolamine, triethanolamine,
N,N,N',N'-tetra(hydroxyethyl)-1,2-diaminoethane,
N,N,N'-tri(hydroxyethyl)- -1,2-diaminoethane,
N,N,N',N'-tetra(hydoxyethylpolyoxyethylene)-1,2-diamin- oethane,
1,4-bis(2-hydroxyethyl)piperazine and 1-(2-hydroxyethyl)piperazin-
e; and other compounds such as nipecotamide, isonipecotamide and
nicotinic acid amide. Examples of commercially available
dispersants employable with the copolymer of the invention include
SIGENOX 105 (trade name, available from Hakko Chemical Co.,
Ltd.).
[0110] It is also preferred for the copolymer (polymer dispersant)
to be used in combination with one or more of amine compounds of
the following formula (6) or (7): 8
[0111] In the formula (6), each of R.sup.61 and R.sup.62
independently represents hydrogen, an alkyl group which may have
one or more substituent groups or an aralkyl group which may have
one or more substituent groups, and R.sup.61 and R.sup.62 may be
combined with each other to form a nitrogen-containing 5- or
6-membered saturated ring (which may further contain 1-3
heteroatoms selected from the group consisting of oxygen atom,
sulfur atom or nitrogen atom); R.sup.63 represents an alkylene
group or an alkylene group having ether linkage therein; and
X.sup.6 is one of the groups of --CON(Y.sup.61)(Y.sup.62),
--OCON(Y.sup.61)(Y.sup.62), --N(Y.sup.63)CO(Y.sup.64) and
--N(Y.sup.63)CON(Y.sup.61)(Y.sup.62) in which each of Y.sup.61,
Y.sup.62, Y.sup.63 and Y.sup.64 independently represents hydrogen
atom, an alkyl group which may have one or more substituent groups,
an aralkyl group which may have one or more substituent groups, or
an aryl group which may have one or more substituent groups.
[0112] In the formula (7), each of R.sup.71, R.sup.72, R.sup.76 and
R.sup.77 independently represents hydrogen atom, an alkyl group
which may have one or more substituent groups or an aralkyl group
which may have one or more substituent groups. Each of R.sup.71,
R.sup.72, R.sup.76 and R.sup.77 may independently be combined with
each other to form a nitrogen-containing 5- or 6-membered saturated
ring (which may further contain 1-3 hetero atoms selected from the
group consisting of oxygen atom, sulfur atom or nitrogen atom).
Each of R.sup.74 and R.sup.75 independently represents an alkylene
group or an alkylene group having ether linkage. Z.sup.7 is one of
the groups of --CON(Y.sup.71)--, --OCON(Y.sup.71)-- and
--N(Y.sup.72)CON(Y.sup.73)-- in which Y.sup.71 Y.sup.72 and
Y.sup.73 mean the same as Y.sup.61, Y.sup.62 and Y.sup.63 in the
formula (6), respectively.
[0113] Examples of the above-mentioned compounds include
bis(2-(1-morpholino)ethyl)terephthalamide.
[0114] Various surface active agents can improve dispersion
stability. Preferred examples of the surface active agents include
an anionic surface active agent such as alkylnaphthalene sulfonic
acid salt or phosphate ester salt; and a cationic surface active
agent such as amine salt; and am amphoteric surface active agent
such as aminocarboxylic acid or betaine.
[0115] The pigment-dispersing composition generally contains the
dispersant (i.e., copolymer of the invention and optionally known
dispersant) in an amount of 0.1 to 200 weight parts, preferably 1
to 50 weight parts, based on 100 weight parts of the pigment.
[0116] As the dispersion medium, organic solvents are generally
used. The amount of the solvent is generally in the range of 10 to
1000 weight parts, preferably 20 to 500 weight parts, based on 100
weight parts of the pigment.
[0117] The pigment composition generally contains the pigment in
the amount of 5 to 80 wt. %, preferably 10 to 70 wt. %.
[0118] Examples of the pigment employable for the invention are as
follows.
[0119] Yellow pigment: C.I. pigment yellow 20, C.I. pigment yellow
24, C.I. pigment yellow 83, C.I. pigment yellow 86, C.I. pigment
yellow 93, C.I. pigment yellow 109, C.I. pigment yellow 110, C.I.
pigment yellow 117, C.I. pigment yellow 125, C.I. pigment yellow
137, C.I. pigment yellow 138, C.I. pigment yellow 139, C.I. pigment
yellow 185, C.I. pigment yellow 147, C.I. pigment yellow 148, C.I.
pigment yellow 153, C.I. pigment yellow 154, C.I. pigment yellow
166, C.I. pigment yellow 168, and C.I. pigment yellow 185;
[0120] Orange pigment: C.I. pigment orange 36, C.I. pigment orange
43, C.I. pigment orange 51, C.I. pigment orange 55, C.I. pigment
orange 59, and C.I. pigment orange 61;
[0121] Red pigment: C.I. pigment red 9, C.I. pigment red 97, C.I.
pigment red 122, C.I. pigment red 123, C.I. pigment red 149, C.I.
pigment red 168, C.I. pigment red 177, C.I. pigment red 180, C.I.
pigment red 192, C.I. pigment red 215, C.I. pigment red 216, C.I.
pigment red 217, C.I. pigment red 220, C.I. pigment red 223, C.I.
pigment red 224, C.I. pigment red 226, C.I. pigment red 227, C.I.
pigment red 228, C.I. pigment red 240, and C.I. pigment red
48:1;
[0122] Violet pigment: C.I. pigment violet 19, C.I. pigment violet
23, C.I. pigment violet 29, C.I. pigment violet 30, C.I. pigment
violet 37, C.I. pigment violet 40, and C.I. pigment violet 50;
[0123] Blue pigment: C.I. pigment blue 15, C.I. pigment blue 15:6,
C.I. pigment blue 22, C.I. pigment blue 60, and C.I. pigment blue
64;
[0124] Green pigment: C.I. pigment green 7, and C.I. pigment green
36
[0125] Brown pigment: C.I. pigment brown 23, C.I. pigment brown 25,
and C.I. pigment brown 26; and
[0126] Black pigment: C.I. pigment black 7.
[0127] Among the above-mentioned pigments, pigments having an
acidic group (e.g., C.I. pigment yellow 138, C.I. pigment yellow
139, C.I. pigment yellow 185 and C.I. pigment yellow 83) are
preferred, and C.I. pigment yellow 138, C.I. pigment yellow 139 and
C.I. pigment yellow 185 are particularly preferred.
[0128] Using the above-described copolymer as the dispersant, the
pigment-dispersing composition of the invention can be prepared,
for example, in the following manners.
[0129] 1) The organic pigment and the dispersant are beforehand
mixed to prepare a pigment composition, and then the prepared
composition is added to an organic solvent or a vehicle.
[0130] 2) The organic pigment and the dispersant are independently
added to an organic solvent or vehicle.
[0131] 3) Each of organic pigment and the dispersant is
independently added to an organic solvent or vehicle to prepare
each dispersion liquid, and then the prepared liquids are mixed. In
this case, only the dispersant may be dispersed with a solvent.
[0132] 4) The organic pigment is added to a solvent or vehicle to
prepare a dispersion liquid, and then the dispersant is added to
the prepared dispersion liquid.
[0133] The term "vehicle" here means a dispersion medium of liquid
coating material containing dispersed pigment, and it generally
consists of a binder component (with which pigment particles are
bound to each other so that the coated film may be hardened) and an
organic solvent (in which the binder is dissolved and diluted).
[0134] Examples of the dispersing apparatuses used in the
above-mentioned preparation method include kneader, roll mill,
attriter, supermill, dissolver, homomixer, and sand mill.
[0135] The process for forming a color image using the pigment
composition comprises, for example, the steps of: coating a
substrate with a coating liquid containing the pigment composition,
and then drying it to form a layer of the composition; or
transferring the composition layer beforehand formed on a temporary
support onto the substrate; forming a layer of known positive or
negative type photosensitive resin composition on the above formed
pigment dispersion composition layer; making the photosensitive
resin layer exposed, and developed; and then removing the
photosensitive resin composition and the pigment dispersion
composition in the unexposed area.
[0136] A colored photosensitive composition can be prepared from
the pigment composition, and thus prepared photosensitive
composition can be used for forming a color image.
[0137] The colored photosensitive composition can be prepared by
mixing the pigment composition and a photosensitive composition. As
the photosensitive compositions, known materials are employable (in
fact, almost all the photosensitive compositions disclosed in
Japanese Patent Provisional Publication No. H3-282404 are
employable). Examples of the photosensitive compositions include a
photosensitive composition comprising a negative type diazo resin
and a binder; a photopolymerizable composition; a photosensitive
composition comprising an azide compound and a binder; and a
cinnamic photosensitive composition.
[0138] The photopolymerizable composition is particularly
preferred. The photopolymerizable composition mainly comprises a
photopolymerization initiator, a multifunctional monomer, and a
binder. Some photosensitive compositions can be developed with an
aqueous alkaline solution, and others can be developed with an
organic solvent. The former photosensitive compositions are
preferred in consideration of environmental preservation and labor
security.
[0139] A binder contained in the colored photosensitive composition
is required not only to give good dispersion stability to the
pigment, but also to suit development with an aqueous alkaline
solution. As the binder having such properties as described above,
the below-described polymers (which generally have an acidic group)
are preferably employed. The polymers practically used can be
selected from the following polymers in consideration of pigment
dispersibility, compatibility with the multifunctional monomer and
the photopolymerization initiator, solubility in alkaline
developer, solubility in organic solvents, strength and a softening
temperature. The polymers are preferably used in combination with
each other.
[0140] Examples of the polymers include copolymer of (meth)acrylic
acid and (meth)acrylic ester, styrene/maleic anhydride copolymer,
and a reaction product of styrene/maleic anhydride copolymer and
alcohols. The copolymer of (meth)acrylic acid and (meth)acrylic
acid ester is preferred. The weight average molecular weight
preferably is in the range of 5,000 to 200,000, in terms of Mw of
polystyrene. The colored photosensitive composition preferably
contains the binder in an amount of 20 to 80 wt. % of the total
solid content.
[0141] Examples of the organic solvents employable for the
preparation of the colored photosensitive composition include
(poly)alkyleneglycol monoalkyl ethers and their acetic acid esters
such as ethyleneglycol monomethyl ether, ethyleneglycol monoethyl
ether, propyleneglycol monomethyl ether, propyleneglycol monoethyl
ether, diethyleneglycol monomethyl ether, and ethyleneglycol
monoethyl ether; acetic acid esters such as ethyl acetate, n-propyl
acetate, isopropyl acetate, n-butyl acetate, and isobutyl acetate;
aromatic hydrocarbons such as benzene, toluene and xylene; ketones
such as methyl ethyl ketone, acetone, methyl isobutyl ketone and
cyclohexanone; and alcohols such as ethanol, propanol, butanol,
hexanol, cyclohexanol, ethylene glycol, diethylene glycol and
glycerol. Preferred are alkyleneglycol monoalkyl ethers and their
acetic acid esters, acetic acid esters, and methyl ethyl ketone.
The amount of the organic solvent preferably is in the range of 50
to 2,000 wt. % of the total solid content. The organic solvents are
employable for the preparation of the pigment-dispersing
composition, as well as the colored photosensitive composition.
[0142] Examples of the multifunctional monomers for the colored
photosensitive composition include (meth)acrylic acid ester,
urethane (meth)acrylate, (meth)acrylamide, allyl compounds, and
vinyl ester. The multi-functional monomers are disclosed in
Japanese Patent Provisional Publication No. S60-258539. Preferred
is a (meth)acrylic acid ester. The amount of the multi-functional
monomer preferably is in the range of 10 to 60 wt. % of the total
solid content of the colored photosensitive composition.
[0143] The photopolymerization initiator used for the colored
photosensitive composition preferably comprises at least one
compound having a molecular extinction coefficient of not less than
50 in the wavelength region of 300 to 500 nm. Examples of these
compounds include aromatic ketones, lophine dimer, benzoin, benzoin
ethers and polyhalogens (Japanese Patent Provisional Publications
No. H2-48664, No. H1-152449 and No. H2-153353). Two or more
compounds can be used in combination. Examples of the initiators
preferably used include a combination of
4,4'-bis(diethylamino)benzophenone and
2-(o-chlorophenyl)-4,5-diphenylimi- dazole dimer; and
4-[p-N,N-di(ethoxycarbonylmethyl)-2,6-di(trichloromethyl-
)-s-triazine]. The amount of the photopolymerization initiator
preferably is in the range of 0.2 to 10 wt. % of the total solid
content of the colored photosensitive composition.
[0144] A color image can be formed using the colored photosensitive
composition by the process basically comprising the following steps
(1)-(3):
[0145] (1) well mixing and kneading the dispersant (copolymer of
the invention), the organic pigment, and the organic solvent to
prepare the pigment dispersion liquid; and then adding the binder
monomer soluble in an aqueous alkaline solution, the
photopolymerization initiator, and optionally a diluting solvent
into the prepared pigment dispersion liquid to prepare the colored
photosensitive composition (coating liquid),
[0146] (2) coating the prepared colored photosensitive composition
onto a substrate and drying the coated composition, or transferring
the composition layer beforehand formed by coating on a temporary
support onto the substrate, to form a colored photosensitive layer,
and
[0147] (3) making the photosensitive layer exposed and developed to
form a pattern image.
[0148] In the process for production of a color filter of liquid
crystal display unit, the above steps (2) and (3) are repeated for
the preparation of each color. The process comprising the
transferring method is described, for example, in Japanese Patent
Provisional Publications No. H4-208940, No. H5-72724, No. H5-80503
and No. H5-173320.
[0149] As the substrate, a transparent sheet such as glass plate
and transparent plastic plate are generally used. One or more of
various commercially available silane coupling agents may be
beforehand added to the composition or coated on the substrate so
as to enhance the adhesion between the composition layer and the
substrate.
[0150] The coating liquid of the colored photosensitive composition
is coated on the substrate by means of coating means such as
spinner, roll coater, bar coater, or curtain coater.
[0151] The composition layer beforehand formed on a temporary
support is preferably transferred onto the substrate by means of
heat roll laminator under atmospheric or reduced pressure.
[0152] Examples of the developers include aqueous solutions of
alkali metal or alkaline earth metal hydroxide or carbonate,
hydrogen carbonate, ammonia, or quaternary ammonium salt.
Particularly preferred is an aqueous solution of sodium
carbonate.
[0153] The present invention is further described by the following
non-restrictive working examples.
EXAMPLE 1
[0154] A yellow pigment dispersion liquid of the following
components were prepared.
5 (Components) C.I. pigment yellow 138 8.28 g Copolymer of the
invention 8.28 g (the compound of Synthesis example 1)
1-Methoxy-2-propyl acetate 63.44 g
[0155] The above components were mixed and kneaded by a motor mill
M50 (produced by Eiger) using zirconia beads (diameter: 0.65 mm) at
a rotation rate of 9 m/s for 9 hours, to prepare a pigment
dispersion liquid.
EXAMPLE 2
[0156] The procedure of Example 1 was repeated except for using the
compound of Synthesis example 2 in place of that of Synthesis
example 1, to prepare a yellow pigment dispersion liquid.
EXAMPLE 3
[0157] The procedure of Example 1 was repeated except for using the
compound of Synthesis example 3 in place of that of Synthesis
example 1, to prepare a yellow pigment dispersion liquid.
EXAMPLE 4
[0158] The procedure of Example 1 was repeated except for using the
compound of Synthesis example 4 in place of that of Synthesis
example 1, to prepare a yellow pigment dispersion liquid.
EXAMPLE 5
[0159] The procedure of Example 1 was repeated except for using
C.I. pigment yellow 139 in place of C.I. pigment yellow 138, to
prepare a yellow pigment dispersion liquid.
EXAMPLE 6
[0160] The procedure of Example 1 was repeated except for using the
following components of green pigment dispersion liquid in place of
that of yellow one, to prepare a green pigment dispersion
liquid.
6 (Components of green pigment dispersion liquid) C.I. pigment
green 36 9.20 g C.I. pigment yellow 138 4.96 g Copolymer of the
invention 14.16 g (the compound of Synthesis example 1)
1-methoxy-2-propyl acetate 51.68 g
Comparison Example 1
[0161] The procedure of Example 1 was repeated except for using
copolymer of dimethylaminoethyl acrylate and methyl methacrylate
(weight ratio: 15/85, weight average molecular weight: 20,000) in
place of the compound of Synthesis example 1, to prepare a yellow
pigment dispersion liquid.
Comparison Example 2
[0162] The procedure of Example 1 was repeated except for using the
following copolymer in place of the compound of Synthesis example
1, to prepare a yellow pigment dispersion liquid.
[0163] The copolymer was prepared by repeating the procedure of
Synthesis example 2 except for using the following monomer
solution.
7 (Components of monomer solution) 2-Hydroxyethyl methacrylate 4.5
weight parts Methacrylic acid 4.5 weight parts Benzyl methacrylate
18.0 weight parts Poly(methyl methacrylate) having 3.0 weight parts
methacryloyl group at one terminal [number average molecular
weight: 6,000, MACROMONOER AA-6 (trade name), available from Toa
Gosei Kagaku Kogyo Co., Ltd.] 1-Methoxy-2-propyl acetate 45 weight
parts
[0164] Each of the above-prepared pigment dispersion liquids was
evaluated in respect of the following characteristics.
[0165] (1) Viscosity: Viscosity of the liquid was measured by means
of E-type viscometer.
[0166] (2) Contrast of image: Contrast of an image given by the
liquid was estimated in the following manner:
[0167] The pigment dispersion liquid was coated on a glass plate to
form a coated layer (thickness: 6 .mu.m). The plate having the
layer was placed between two polarizers. The polarizers were set so
that the polarizing axis of each polarizer might be parallel, and
then transmittance was measured. In the case that the axes of
polarization were perpendicular to each other, transmittance was
also measured. Thereafter, the transmittance ratio was calculated
to determine the contrast of image (ref. "Seventh Color Optics
Conference (1990)", a color filter for 10.4" size TFT-LCD display
of 512 colors, Ueki, Koseki, Fukunaga and Yamanaka).
EXAMPLE 7
[0168] (Preparation of Green Photosensitive Composition for Color
Filter)
[0169] A photopolymerizable photosensitive composition of the
following components was prepared.
8 (Components of photopolymerizable photosensitive composition)
Methacrylic acid/benzyl methacrylate 30 g copolymer (molar ratio:
28/72, weight average molecular weight: 30,000) Pentaerythritol
tetracrylate 7.7 g 4-[p-N,N-Di(ethoxycarbonylmethyl)- 0.3 g
2,6-di(trichloromethyl)-s-triazine] Hydroquinone monomethyl ether
0.01 g 1-Methoxy-2-propyl acetate 62 g
[0170] To the prepared photosensitive composition, 45 g of a
pigment dispersion liquid of C.I. pigment green 36 dispersed in
1-methoxy-2-propyl acetate (solid content: 33%) and 40 g of the
yellow pigment dispersion liquid of Example 1 (for color
compensation) were added to prepare a green photosensitive
composition for color filter.
EXAMPLE 8
[0171] The procedure of Example 7 was repeated except for using the
yellow pigment dispersion liquid of Example 2 in place of that of
Example 1, to prepare a green photosensitive composition for color
filter.
EXAMPLE 9
[0172] The procedure of Example 7 was repeated except for using the
yellow pigment dispersion liquid of Example 3 in place of that of
Example 1, to prepare a green photosensitive composition for color
filter.
EXAMPLE 10
[0173] The procedure of Example 7 was repeated except for using the
yellow pigment dispersion liquid of Example 4 in place of that of
Example 1, to prepare a green photosensitive composition for color
filter.
EXAMPLE 11
[0174] The procedure of Example 7 was repeated except for using the
yellow pigment dispersion liquid of Example 5 in place of that of
Example 1, to prepare a green photosensitive composition for color
filter.
EXAMPLE 12
[0175] The procedure of Example 7 was repeated except for using 85
g of the green pigment dispersion liquid of Example 6 in place of
45 g of that prepared in Example 7 and 40 g of the yellow pigment
dispersion liquid of Example 1, to prepare a green photosensitive
composition for color filter.
Comparison Example 3
[0176] The procedure of Example 7 was repeated except for using the
yellow pigment dispersion liquid of Comparison Example 1 in place
of that of Example 1, to prepare a green photosensitive composition
for color filter.
Evaluation
[0177] With respect to each above-prepared green photosensitive
composition for color filter, the viscosity was measured in the
same manner as described above.
[0178] Further, a color filter was prepared from each
photosensitive composition in the following manner:
[0179] The photosensitive composition was coated on a glass plate
by means of spinner, and dried at 100.degree. C. for 2 minutes to
form a film (thickness: about 2 .mu.m). In a stream of nitrogen
gas, the film was exposed to light coming from ultra-high pressure
mercury lamp and then developed with 1% aqueous solution-of sodium
carbonate to prepare a color filter.
[0180] The contrast of an image given by the prepared filter was
estimated in the manner described above.
[0181] The results are shown in Table 1.
9 TABLE 1 Contrast pigment photosensitive Viscosity (cp) dispersion
composition Ex. 1 40 300 -- Ex. 2 90 270 -- Ex. 3 100 250 -- Ex. 4
45 380 1300 Ex. 5 150 250 -- Ex. 6 70 1300 -- Ex. 7 70 -- 1250 Ex.
8 70 -- 1100 Ex. 9 70 -- 1200 Ex. 10 70 -- 1350 Ex. 11 70 -- 1350
Ex. 12 70 -- 1300 C. Ex. 1 more than 1200 150 -- C. Ex. 2 too
viscous* -- -- C. Ex. 3 200 -- 500 Remarks*: the liquid of
Comparison Example 2 was too viscous to disperse the pigment.
[0182] The results set forth in Table 1 indicate that the pigment
dispersion liquid containing the copolymer (dispersant) of the
invention shows a low viscosity and that the color filter prepared
from the colored photosensitive composition of the invention gives
an image of high contrast. This fact suggests that the pigment
particles are dispersed finely enough to give an image of high
contrast.
[0183] The pigment dispersion composition of the invention has
excellent properties such as a high dispersion stability, a high
fluidity, and a high coloring power. Further, the colored
photosensitive composition of the invention is favorable for
development with an alkaline developer and shows a high coloring
power or a high contrast to form a color image of a high
quality.
* * * * *