Ink composition for color ink jet recording and recording method with the same

A magenta ink composition comprising C.I. Direct Red 227 in an amount of 0.3 to 3.5% by weight, a water-soluble high boiling low volatility organic solvent and water is disclosed. A set comprising the magenta ink composition, a yellow ink composition comprising a 1:3 to 3:1 by weight mixture of C.I. Direct Yellow 86 and C.I. Direct Yellow 132 in an amount of 0.3 to 3.0% by weight and a cyan ink composition comprising at least one of C.I. Direct Blue 86 and C.I. Direct Blue 199 in an amount of 1.0 to 4.0% by weight is also disclosed. An ink jet recording method using the foregoing ink set is further disclosed. The ink composition provides an excellent color reproducibility range and causes no deterioration of printed matter.

FIELD OF THE INVENTION 
The present invention relates to an ink jet composition for color ink jet 
recording and a color ink jet recording method. 
BACKGROUND OF THE INVENTION 
In the formation of a color image by an ink jet recording method, at least 
a magenta ink, a yellow ink and a cyan ink are normally used. It is 
important that these inks each have an excellent color reproducibility 
range. It is further important that even when a magenta ink, a yellow ink 
and a cyan ink are superposed on each other to form red, green, blue and 
black colors, a good color reproducibility can be realized. 
Further, the color ink composition for use in ink jet recording must 
satisfy general requirements for ink composition for ink jet recording. In 
some details, the color ink composition must maintain its composition and 
physical properties during storage to prevent itself from clogging the 
nozzle. 
In respect to these requirements, JP-A-5-214259 (The term "JP-A" as used 
herein means an "unexamined published Japanese patent application") 
discloses that an excellent color reproducibility can be realized by the 
use of an ink set comprising a specific dye set consisting of C.I. Acid 
Yellow 23, C.I. Direct Red 227 and C.I. Acid Blue 9. Further, U.S. Pat. 
No. 5,273,573 discloses that an excellent color reproducibility can be 
realized by the use of an ink set comprising a specific dye set consisting 
of C.I. Acid Yellow 23, C.I. Acid Red 52 and C.I. Acid Blue 9. 
However, printed matters obtained by the conventional ink jet recording 
method employing these dyes are disadvantageous in that they are apt to 
deterioration when exposed to water or light. When printing is performed 
on a paper or film adapted for ink jet recording, fastness is particularly 
required. Fastness can be improved by improving the paper. However, this 
approach leaves something to be desired in solving the problems of the 
prior art ink jet recording method. In other words, the prior art color 
ink jet recording method is disadvantageous in that when-exposed to light, 
the printed matters are apt to discoloration. Further, since two or three 
color inks are overtyped to form an image in the color ink jet recording 
method as mentioned above, an approach which comprises reducing the duty 
(duty: number of ink jetted dots per unit area) of the overtyped area can 
be employed. However, this approach is disadvantageous in that the ink can 
be attached to the overtyped area more than to a single ink area. The 
resulting printed matters are apt to bleeding that impairs the image 
quality when allowed to stand in a high humidity atmosphere. 
The inventors made extensive studies of an approach which satisfies 
requirements for ink composition for color ink jet recording method, ink 
composition set for color ink jet recording method and color ink jet 
recording method to solve the foregoing problems. As a result, it was 
found that the foregoing problems can be solved by the use of a magenta 
ink composition comprising a specific dye and a solvent in combination or 
an ink composition set comprising the magenta ink composition, a specific 
yellow ink composition and a specific cyan ink composition. 
SUMMARY OF THE INVENTION 
It is therefore a major object of the present invention to provide an ink 
composition, ink composition set and recording method which are 
insusceptible to bleeding on the printed matter due to moisture and 
exhibit an excellent light resistance regardless of printing duty in the 
color ink jet recording method. 
It is another object of the present invention to provide an ink 
composition, ink composition set and recording method which exhibit an 
excellent color reproducibility in the color ink jet recording method. 
The present invention concerns a magenta ink composition for color ink jet 
recording comprising at least a dye, a water-soluble high boiling low 
volatility organic solvent and water, wherein as said dye there is 
contained C.I. Direct Red 227 in an amount of from 0.3 to 3.5% by weight. 
The present invention also concerns a color ink jet recording method which 
comprises forming a color image with at least a magenta ink composition, a 
yellow ink composition and a cyan ink composition, wherein as said magenta 
ink composition there is used the foregoing magenta ink composition. 
The present invention further concerns a set of ink composition sets for 
color ink jet recording each containing at least a dye, a water-soluble 
high boiling low volatility organic solvent and water, comprising in 
combination a magenta ink composition having C.I. Direct Red 227 
incorporated therein as a dye in an amount of from 0.3 to 3.5% by weight, 
a yellow ink composition having a 1:3 to 3:1 mixture by weight of C.I. 
Direct Yellow 86 and C.I. Direct Yellow 132 incorporated therein as a dye 
in an amount of from 0.3 to 3.0% by weight, and a cyan ink composition 
having a dye selected from the group consisting of C.I. Direct Blue 86 and 
C.I. Direct Blue 199 incorporated therein as a dye in an amount of from 
1.0 to 4.0% by weight. 
The present invention still further concerns a color ink jet recording 
method which comprises the formation of a color image with at least a 
magenta ink composition, a yellow ink composition and a cyan ink 
composition, wherein the foregoing ink composition set is used. 
The magenta ink composition according to the present invention comprises 
C.I. Direct Red 227 in an amount of from 0.3 to 3.5% by weight, preferably 
from 0.5 to 2.5% by weight based on the total weight of the foregoing 
magenta ink composition. The magenta ink composition according to the 
present invention allows the reproduction of an ideal magenta tone. In 
particular, an ideal color tone can be obtained with an ordinary paper, 
especially with an ordinary acid paper. 
If the content of the foregoing dye in the magenta ink composition 
according to the present invention falls below 0.3% by weight, a 
sufficient color developability cannot be obtained. On the contrary, if 
the content of the foregoing dye exceeds 3.5% by weight, the resulting 
magenta ink composition clogs the nozzle. In other words, if the content 
of the foregoing dye deviates from the above defined range, the resulting 
color tone is a bluish or reddish magenta even when the magenta ink 
composition is printed singly. Thus, an ideal magenta tone cannot be 
reproduced. When overtyped on or by the other color ink compositions, the 
magenta ink composition cannot provide reproduction of a good red or blue 
tone. Further, a great difference in color reproducibility can be produced 
between ordinary neutral paper and ordinary acid paper. Moreover, the 
magenta ink composition can easily clog the ink nozzle of the recording 
head. If the content of the foregoing dye falls within the range of from 
0.5 to 2.5% by weight, a more natural magenta hue can be obtained to 
advantage. 
The yellow ink composition to be incorporated in the ink composition set 
comprising the foregoing magenta ink composition and the yellow ink 
composition in combination comprises a 1:3 to 3:1, preferably 1:2 to 2:1 
mixture (by weight) of C.I. Direct Yellow 86 and C.I. Direct Yellow 132 
each in an amount of from 0.3 to 3.0% by weight, preferably from 0.5 to 
2.0% by weight, based on the total weight of the yellow ink composition. 
If the content of the foregoing two dyes deviates from the above defined 
range, a good red tone cannot be reproduced even when these ink 
compositions are overtyped. Further, a great difference in color 
reproducibility can be produced between ordinary neutral paper and 
ordinary acid paper. Moreover, the ink composition set can easily clog the 
ink nozzle of the recording head. 
The cyan ink composition to be incorporated in the ink composition set 
comprising the foregoing magenta ink composition and the cyan ink 
composition in combination comprises at least a dye selected from the 
group consisting of C.I. Direct Blue 86 and C.I. Direct Blue 199 in an 
amount of from 1.0 to 4.0% by weight, preferably from 1.5 to 3.5% by 
weight, based on the total weight of the cyan ink composition. If the 
content of the foregoing two dyes deviates from the above defined range, a 
good blue tone cannot be reproduced even when these ink compositions are 
overtyped. Further, a great difference in color reproducibility can be 
produced between ordinary neutral paper and ordinary acid paper. Moreover, 
the ink composition set can easily clog the ink nozzle of the recording 
head. 
The foregoing magenta ink composition, yellow ink composition and cyan ink 
composition each comprise as solvents a water-soluble high boiling low 
volatility organic solvent and water besides the foregoing specific dyes. 
The foregoing water-soluble high boiling low volatility organic solvent is 
not specifically limited so far as it is a solvent for the foregoing dyes. 
Specific preferred examples of the water-soluble high boiling low 
volatility organic solvent will be given below. 
(1) Alkylene glycol compound represented by the following general formula: 
EQU R.sup.11 O--CH.sub.2 --CH(R.sup.13)--O!.sub.t --R.sup.12 
wherein R.sup.11 and R.sup.12 each independently represent a hydrogen atom, 
a methyl group or an ethyl group; R.sup.13 represents a hydrogen atom or a 
C.sub.1-4 lower alkyl group, preferably a hydrogen atom, a methyl group or 
an ethyl group; and t represents an integer of from 1 to 20, preferably 
from 1 to 15. Examples of such an alkylene glycol compound include glycol 
compounds such as ethylene glycol, diethylene glycol, triethylene glycol, 
propylene glycol, dipropylene glycol, polyethylene glycol and 
polypropylene glycol, monoether compounds such as ethylene glycol 
monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether 
and triethylene glycol monomethyl (or ethyl) ether, and diether compounds 
such as triethylene glycol dimethyl (or ethyl) ether. 
(2) Divalent alcohol compound represented by the general formula: 
EQU HO--CH.sub.2 CH.sub.2 --(R.sup.21).sub.s --OH 
wherein R.sup.21 represents a C.sub.1-4 straight-chain or branched alkylene 
group; and s represents an integer of from 1 to 6, preferably from 1 to 4. 
Examples of such a divalent alcohol compound include 1,3-propanediol, 
1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-pentanediol, 
1,4-pentanediol, 1,3-pentanediol, 1,2-pentanediol, 1,6-hexanediol, 
1,5-hexanediol, 1,4-hexanediol, 1,3-hexanediol, and 1,2-hexanediol. 
(3) Trivalent alcohol compound represented by the general formula: 
EQU HO--CH(R.sup.31)--C(R.sup.32)(OH)--R.sup.33 
wherein R.sup.31 and R.sup.32 each independently represent a hydrogen atom 
or a C.sub.1-4 lower alkyl group, preferably a hydrogen atom, a methyl 
group or an ethyl group; and R.sup.33 represents a C.sub.1-6 
straight-chain or branched hydroxyalkyl group. Examples of such a 
trivalent alcohol compound include glycerin, and 1,2,6-hexanetriol. 
(4) Ethanolamine compound represented by the general formula: 
EQU (R.sup.42).sub.v --N--CH.sub.2 CH(R.sup.41)OH!.sub.u 
wherein R.sup.41 represents a hydrogen atom or a C.sub.1-4 lower alkyl 
group, preferably a hydrogen atom, a methyl group or an ethyl group; 
R.sup.42 represents a hydrogen atom, a C.sub.1-4 lower alkyl group or 
--CH.sub.2 CH(R.sup.41)OH!; u represents an integer of from 1 to 3; and v 
represents 0 or an integer 1 or 2, with the proviso that the sum of u and 
v is 3. Examples of such a compound include monoethanolamine, 
N,N-dimethylethanolamine, N,N-diethylethanolamine, diethanolamine, 
triethanolamine, triisopropanolamine, and N-n-butyldiethanolamine. 
(5) Other preferred examples of the water-soluble high boiling low 
volatility organic solvent include a 2- or 3-pyrrolidone compound which 
may be optionally substituted by a methyl group or an ethyl group in 
N-position. Examples of such a 2- or 3-pyrrolidone compound include 
2-pyrrolidone, N-methyl-2-pyrrolidone, imidazolidinone compound which may 
be optionally substituted by two methyl groups in N-position, such as 
1,3-dimethyl-2-imidazolidinone, C.sub.2-4 thioglycol compound such as 
thioglycol and thiodiglycol, trimethylol-substituted C.sub.2-4 lower 
alkane compound such as trimethylolethane and trimethylolpropane, and 
urea. 
In the present invention, the organic solvents listed in the foregoing 
groups (1) to (5) may be used singly or in combination. These organic 
solvents act to prevent the clogging of the nozzle and thus can be used as 
humectants. However, the hygroscopicity of these solvents worsens bleeding 
on paper adapted for ink jet recording and printed film due to humidity. 
Therefore, the foregoing solvent is preferably incorporated in the ink 
composition in an amount of from 5 to 30% by weight, more preferably from 
9 to 20% by weight based on the total weight of the ink composition. 
The ink composition set according to the present invention comprises in 
combination the foregoing magenta ink composition, yellow ink composition 
and cyan ink composition each having at least the foregoing specific dye, 
water-soluble high boiling low volatility organic solvent, and water 
incorporated therein. 
The tone of red, green and blue formed by overtyping two out of the 
foregoing magenta ink composition, yellow ink composition and cyan ink 
composition and black formed by overtyping the three ink compositions, not 
to mention magenta, yellow and cyan obtained directly by ink jet printing 
of these ink compositions, respectively, are closely related to the 
combination of the kind and amount of dyes. Thus, an ink composition set 
comprising the magenta ink composition of the present invention, and the 
foregoing yellow ink composition and cyan ink composition can be obtained. 
Further, a printed matter can be obtained which shows an almost ideal tone 
on the black area formed by overtyping the three colors from the ink 
composition set comprising the magenta ink composition of the present 
invention, and the foregoing yellow ink composition and cyan ink 
composition. Moreover, a printed matter can be obtained which shows an 
excellent color reproducibility of an ink comprising a black dye. In the 
ink composition set according to the present invention, if dyes of kind 
different from the foregoing specific dye are used, or if ink compositions 
comprising the foregoing dyes in an amount deviating from the above 
defined range are used, the various colors cannot be provided with an 
ideal tone. Moreover, such an ink composition set can easily clog the 
nozzle of the recording head and thus cannot be stably jetted. 
Bleeding on the paper adapted for ink jet recording and printed film due to 
moisture or the light resistance of these materials is closely related to 
the dyes incorporated in the ink composition. Thus, the ink composition 
set of the present invention is extremely effective for the preservability 
of the printed matter. 
The various ink compositions constituting the ink composition set of the 
present invention may optionally comprise an organic solvent other than 
the foregoing water-soluble high boiling low volatility organic solvent 
incorporated therein. Specific examples of the organic solvent include 
amides such as dimethylformamide and dimethylacetamide, ketones and ketone 
alcohols such as acetone and diacetone alcohol, cyclic ethers such as 
tetrahydrofuran and dioxane, C.sub.1-5 alkylalcohols such as methyl 
alcohol, ethyl alcohol, n-propyl alcohol and n-butyl alcohol, sulfolane, 
pyrrolidone, N-methyl-2-imidazolidinone, and 1,5-pentanediol. These 
organic solvents may be used singly or in admixture. Such an organic 
solvent is preferably used in an amount of not more than 10% by weight 
based on the total weight of the foregoing ink composition. 
The various ink compositions constituting the ink composition set of the 
present invention may optionally comprise a lower alkyl ether of 
polyvalent alcohol. A preferred example of the lower alkyl ether of 
polyvalent alcohol is a compound represented by the following general 
formula: 
EQU R.sup.51 O--CH.sub.2 --CH(R.sup.53)--O!.sub.t --R.sup.52 
wherein R.sup.51 and R.sup.52 each independently represent a hydrogen atom 
or a C.sub.3-6 alkyl group (preferably butyl group); R.sup.53 represents a 
hydrogen atom or a C.sub.1-4 lower alkyl group, preferably a hydrogen 
atom, a methyl group or an ethyl group; and t represents an integer of 
from 1 to 8, preferably from 1 to 4, with the proviso that at least one of 
R.sup.51 and R.sup.52 is a C.sub.3-6 alkyl group (preferably butyl group). 
Examples of the lower alkyl ether of polyvalent alcohol include 
monoethylene glycol-C.sub.3-6 alkyl ether, diethylene glycol-C.sub.3-6 
alkyl ether, triethylene glycol-C.sub.3-6 alkyl ether, monopropylene 
glycol-C.sub.3-6 alkyl ether, dipropylene glycol-C.sub.3-6 alkyl ether, 
and tripropylene glycol-C.sub.3-6 alkyl ether. Preferred among these lower 
alkyl ethers of polyvalent alcohol are triethylene glycol monobutyl ether, 
diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, 
diethylene glycol monomethyl ether, and propylene glycol monobutyl ether. 
Most preferred among these lower alkyl ethers of polyvalent alcohol is 
triethylene glycol monobutyl ether. The content of such a lower alkyl 
ether of polyvalent alcohol is preferably from 7 to 12% by weight, more 
preferably from 7 to 10% by weight based on the total weight of the ink 
composition. 
The sum of the content of the water-soluble high boiling low volatility 
organic solvent and the lower alkyl ether of polyvalent alcohol in the ink 
composition of the present invention is preferably from 15 to 30% by 
weight based on the total weight of the ink composition. This is because 
that if the sum of the content of the two components falls within the 
above defined range, ink compositions excellent in all of color 
reproducibility, discharge stability, and intermittent discharge 
characteristics on ordinary paper can be obtained. 
The various ink compositions constituting the ink composition set of the 
present invention may optionally comprise an acetylene glycol represented 
by the following general formula (I) incorporated therein: 
##STR1## 
wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each independently represent 
a C.sub.1-6 straight-chain or branched alkyl group; and the sum of n and m 
is from 0 to 30, preferably from 0 to 15. 
Specific examples of the acetylene glycol will be given in Table 1. 
TABLE 1 
______________________________________ 
R.sup.1 R.sup.2 R.sup.3 
R.sup.4 
n + m 
______________________________________ 
No. 1 iso-Butyl Methyl Methyl iso-Butyl 
10 
No. 2 iso-Butyl Methyl Methyl iso-Butyl 
3.5 
No. 3 Ethyl Methyl Methyl Ethyl 10 
No. 4 Methyl Methyl Methyl Methyl 0 
No. 5 Ethyl Methyl Methyl Ethyl 0 
No. 6 iso-Butyl Methyl Methyl iso-Butyl 
0 
______________________________________ 
Most preferred among the compounds shown in Table 1 is No. 1 acetylene 
glycol. As these acetylene glycols there may be used commercially 
available products. For example, Surfynol 82, Surfynol 104, Surfynol 440 
and Surfynol 465 (manufacturer: Air Product and Chemicals, Inc.; dealer: 
Shin-Etsu Chemical Co., Ltd.) may be used. The content of the acetylene 
glycol is preferably from 0.5 to 1.2% by weight, more preferably from 0.5 
to 1% by weight based on the total weight of the ink composition. 
The combination of the foregoing lower alkyl ether of polyvalent alcohol 
and acetylene glycol in the foregoing respective content can prevent the 
deterioration of printing quality due to color stain across adjacent dots, 
which often presents a problem in the color ink jet recording method. 
The various ink compositions constituting the ink composition set of the 
present invention each may comprise an additive for improving various 
properties of ink composition. For example, for the purpose of controlling 
various physical properties such as viscosity, surface tension, pH and 
specific resistivity and inhibiting corrosion and fungus growth, anionic 
surface active agents such as aliphatic acid salt, ester alkylsulfate, 
alkylbenzenesulfonic acid and alkylnaphthalenesulfonic acid salt, nonionic 
surface active agents such as acetylene glycol, polyoxyethylene 
alkylphenyl ether, polyoxyethylene alkylphenyl ether, ester 
polyoxyethylenealiphate and ester sorbitanealiphate, water-soluble natural 
or synthetic high molecular compounds such as cellulose, polyvinyl 
pyrrolidone, polyvinyl alcohol and water-soluble resin, diethanolamines, 
triethanolamines, inorganic salts such as lithium chloride, ammonium 
chloride and sodium chloride, and benzotriazole may be used. 
The color ink jet recording method of the present invention can be 
implemented by inserting a common ink cartridge loaded with the foregoing 
magenta ink composition of the present invention into a common color ink 
jet recording apparatus. Alternatively, the color ink jet recording method 
of the present invention can be implemented by inserting the foregoing ink 
cartridge loaded with the foregoing magenta ink composition, the foregoing 
ink cartridge loaded with the foregoing yellow ink composition and the 
foregoing ink cartridge loaded with the foregoing cyan ink composition 
into the color ink jet recording apparatus in combination. The color ink 
jet recording method of the present invention can also be implemented by 
the use of a color ink jet recording apparatus with an ink cartridge 
having the foregoing magenta ink composition, the foregoing yellow ink 
composition and the foregoing cyan ink composition loaded in the 
respective compartment. 
The ink jet recording method according to the present invention performs 
color ink jet recording, preferably with the foregoing magenta ink 
composition, the foregoing yellow ink composition and the foregoing cyan 
ink composition, optionally combined with a common black ink composition. 
A color ink jet recording with the foregoing magenta ink composition, a 
common yellow ink composition other than the foregoing yellow ink 
composition and a common cyan ink composition other than the foregoing 
cyan ink composition, optionally combined with a common black ink 
composition, is included in the present invention. In the color ink jet 
recording method according to the present invention, the reproduction of 
the three colors, i.e., magenta, yellow and cyan is excellent. In 
addition, by overtyping any two of these ink compositions, red, green and 
blue with an almost ideal tone can be obtained free from the effect of the 
quality of the recording paper. In other words, red formed by overtyping 
the magenta ink and the yellow ink on each other and blue formed by 
overtyping the magenta ink and the cyan ink on each other on various 
recording papers are the reproduction of the respective color with an 
almost ideal tone free from the effect of the quality of the paper (e.g., 
ordinary recording paper with a high acidity). 
In a preferred embodiment of the present invention, the amount of the 
magenta ink composition, yellow ink composition and cyan ink composition 
to be jetted for the formation of red, green or blue may be equal. In 
general, it is theoretically possible to control the tone of red, green 
and blue formed by overtyping the foregoing ink compositions by properly 
controlling the amount of the yellow, magenta and cyan ink compositions to 
be jetted through the nozzle every tone. However, this approach is too 
complicated to be put into practical use. In other words, the 
differentiation of the jetted amount of the magenta ink composition from 
blue to green is not practical. Accordingly, the present invention is very 
advantageous in that red, green and blue can be reproduced with a good 
tone while keeping the jetted amount of the magenta, yellow and cyan ink 
compositions constant.