Ink, and ink-jet recording method and instruments using the same

Disclosed herein is a yellow ink comprising at least two yellow dyes and a liquid medium dissolving or dispersing the dyes therein, wherein the ink comprises a dye represented by the following general formula (1) in the state of a free acid, and a yellow dye having a SO.sub.3 H group as a main solubilizing group in the state of a free acid and having its position in the L*a*b* chromaticity diagram at b*=xa* (3.ltoreq.x.ltoreq..infin.): ##STR1##

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an ink, and an ink-jet recording method, 
instruments and recording apparatus using such an ink. 
2. Related Background Art 
Inks with greatly various manners of being composed have heretofore been 
reported in respect of inks for ink-jet, and various investigations have 
been made on the reliability as to ink-jet. Nowadays, printers are 
required to permit high-speed printing. With such a requirement, inks are 
also required to have good high-frequency responsiveness. Besides, inks 
for ink-jet are required to have better reliability (from the viewpoint of 
ecology) because the life of heads is extended. In addition, the inks are 
also required to have properties that images having high water fastness 
can be provided on, in particular, so-called plain paper such as 
neutralized paper, and good color tone must be achieved in color images. 
References are given to, in particular, yellow inks. An ink using C.I. 
Direct Yellow 86 has been proposed in Japanese Patent Publication No. 
3-6193. According to this ink, considerable improvements are recognized on 
the storage stability and crusting of the ink. However, the ink involves a 
drawback that its ejection property becomes unstable when conducting 
continuous printing. In addition, images formed on plain paper with the 
ink are insufficient in water fastness and color tone. Japanese Patent 
Application Laid-Open Nos. 5-194890 and 61-2771 have proposed, 
respectively, a yellow ink comprising C.I. Direct Yellow 86 and C.I. Acid 
Yellow 23, and a yellow ink comprising a dye represented by the general 
formula 
##STR2## 
wherein M.sub.1 and M.sub.2 may be identical with or different from each 
other and are independently hydrogen, an alkali metal, ammonium or organic 
amino group, and X is an alkylamine or alkoxyalkylamine residue having 6 
to 18 carbon atoms. Both inks provide images having good color tone, but 
are also insufficient in water fastness of images formed on plain paper. 
EP 0468647A1 has proposed yellow dyes having excellent water fastness. When 
inks comprising these water-fast dyes are used in an ink-jet printer, the 
water fastness of the resulting image is improved. On the other hand, 
print irregularity or ejection failure may be caused due to the crusting 
of the inks within nozzles. In addition, the inks also involve a problem 
that printing is disordered while conducting continuous printing, and so 
their ejection properties become unstable. 
As described above, any yellow ink, which satisfies reliability as to 
ink-jet such as print quality upon continuous printing, and also the water 
fastness of the resulting image, and provides images having good color 
tone, has not been yet discovered. 
SUMMARY OF THE INVENTION 
It is accordingly an object of the present invention to provide a yellow 
ink which satisfies reliability as to various properties such as print 
quality when conducting continuous printing in an ink-jet recording 
apparatus and storage stability without the least problem, and can provide 
images good in both water fastness and color tone on plain paper, and an 
ink-jet recording method and instruments using such an ink. 
The above object can be achieved by the present invention described below. 
According to the present invention, there is thus provided a yellow ink 
comprising at least two yellow dyes and a liquid medium dissolving or 
dispersing the dyes therein, wherein the ink comprises a dye represented 
by the following general formula (1) in the state of a free acid, and a 
yellow dye having a SO.sub.3 H group as a main solubilizing group in the 
state of a free acid and having its position in the L*a*b* chromaticity 
diagram at b*=xa* (3.ltoreq.x.ltoreq..infin.): 
##STR3## 
wherein Ar and Ar.sub.1 are independently an aryl group or a substituted 
aryl group, at least one of which has at least one substituent group 
selected from the group consisting of COOH and COSH, J and J.sub.1 are 
independently a group selected from the group consisting of groups 
represented by the general formulae 
##STR4## 
in which R.sub.5 is a radical selected from the group consisting of H, 
alkyl groups, substituted alkyl groups, alkoxy groups, halogens, CN, a 
ureido group and NHCOR.sub.6 (R.sub.6 being a radical selected from the 
group consisting of H, alkyl groups, substituted alkyl groups, aryl 
groups, substituted aryl groups, aralkyl groups and substituted aralkyl 
groups), T is an alkyl group, W is a radical selected from the group 
consisting of H, CN, CONR.sub.10 R.sub.11, pyridinium and COOH, (m) is an 
alkylene chain having 2 to 8 carbon atoms, and B is a radical selected 
from the group Consisting of H, alkyl groups and COOH, R.sub.1, R.sub.2, 
R.sub.3, R.sub.4, R.sub.10 and R.sub.11 are independently a radical 
selected from the group consisting of H, alkyl groups and substituted 
alkyl groups, L is a divalent organic bonding group, n is 0 or 1, X is a 
carbonyl group or a group selected from the group consisting of groups 
represented by the general formulae 
##STR5## 
in which Z is a group selected from the group consisting of OR.sub.7, 
SR.sub.7 and NR.sub.8 SR.sub.9, Y is a radical selected from the group 
consisting of H, Cl, CN and Z, E is a radical selected from the group 
consisting of Cl and CN, and R.sub.7, R.sub.8 and R.sub.9 are 
independently a radical selected from the group consisting of H, alkenyl 
groups, substituted alkenyl groups, alkyl groups, substituted alkyl 
groups, aryl groups, substituted aryl groups, aralkyl groups and 
substituted aralkyl groups, or R.sub.8 and R.sub.9 form a 5- or 6-membered 
ring together with the nitrogen atom to which they are bonded, with the 
proviso that (1) Ar and Ar.sub.1 have at least two groups selected from 
COOH and COSH where they have no SO.sub.3 H group, or (2) Ar and Ar.sub.1 
have groups selected from COOH and COSH of at least the same number as the 
number of SO.sub.3 H groups where they have one or more SO.sub.3 H groups. 
According to the present invention, there is also provided an ink-jet 
recording method comprising ejecting an ink out of an orifice in 
accordance with recording signals to conduct recording on a recording 
medium, wherein said ink is the ink described above. 
According to the present invention, there is further provided a recording 
unit comprising an ink container portion with an ink held therein and a 
head from which the ink is ejected, wherein said ink is the ink described 
above. 
According to the present invention, there is still further provided an ink 
cartridge comprising an ink container portion with an ink held therein, 
wherein said ink is the ink described above. 
According to the present invention, there is yet still further provided an 
ink-jet recording apparatus comprising a recording unit having an ink 
container portion with an ink held therein and a head from which the ink 
is ejected, wherein said ink is the ink described above. 
According to the present invention, there is yet still further provided an 
ink-jet recording apparatus comprising a recording head for ejecting an 
ink, an ink cartridge having an ink container portion with the ink held 
therein, and an ink feeder for feeding the ink from the ink cartridge to 
the recording head, wherein said ink is the ink described above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will hereinafter be described in detail. 
The present inventors have carried out an extensive investigation as to 
various manners of ink compositions. As a result, it has been found that a 
yellow ink composed of a liquid medium containing at least two yellow 
dyes, wherein a dye represented by the general formula (1) in the state of 
a free acid is used in combination with a yellow dye having a SO.sub.3 H 
group as a main solubilizing group in the state of a free acid and having 
its position in the L*a*b* chromaticity diagram at b*=xa* 
(3.ltoreq.x.ltoreq..infin.), has good reliability as to ejection stability 
when conducting continuous printing and long-term storage stability, and 
can provide images good in both water fastness and color tone. 
This is considered to be attributable to the fact that when a single dye is 
used in an ink, the dye tends to form micelles, while when dyes different 
from each other in structure coexist in an ink, a synergistic effect 
occurs between them, so that they are unlikely to form micelles and always 
remain stably dissolved in the ink. Therefore, such an ink may be improved 
in reliability as to ejection stability when conducting continuous 
printing and ejection stability after being stored for a long period of 
time. In particular, it has been found that a dye represented by the 
general formula (1) can achieve good reliability (as to ejection stability 
when conducting continuous printing, ejection stability after being stored 
for a long period of time, etc.) by using it in combination with a yellow 
dye having a SO.sub.3 H group as a main solubilizing group in the state of 
a free acid and having its position in the L*a*b* chromaticity diagram at 
b*=xa* (3.ltoreq.x.ltoreq..infin.). This level of reliability cannot be 
achieved by the dye represented by the general formula (1) alone, and 
besides, the combined use permits the provision of images good in both 
water fastness and color tone. 
For example, when a yellow ink comprising the dye represented by the 
general formula (1) and the yellow dye having a SO.sub.3 H group as a main 
solubilizing group in the state of a free acid and having its position in 
the. L*a*b* chromaticity diagram at b*=xa* (3.ltoreq.x.ltoreq..infin.) is 
used and a* is made near 0, color tones of red and green, which are 
secondary colors, can also be improved, to say nothing of preferable 
yellow, and moreover, the reliability as to print quality when conducting 
continuous printing, long-term storage stability, etc. can be more 
improved than when producing, for example, a tint of a* being near 0 by 
using one kind of dye. 
When the yellow dye having a SO.sub.3 H group as a main solubilizing group 
in the state of a free acid and having its position in the L*a*b* 
chromaticity diagram at b*=xa* (3.ltoreq.x.ltoreq..infin.) is a dye having 
a symmetrical structure inserted with an organic bonding group, the dye is 
better balanced and becomes stable in structure. It is hence considered 
that the reliability is more enhanced. It has also been found that among 
such dyes, a yellow dye represented by the general formula (8), which will 
be described subsequently, is most compatible with the dye represented by 
the general formula (1) and is excellent for the combined use with the dye 
represented by the general formula (1) taking a balance between the 
reliability as to ejection stability and the like, and water fastness, 
color tone and the like into consideration. 
It has further found that when a monovalent alkali metal not contained in 
the dyes is added to the ink, the balance between the reliability as to 
ejection stability and the like, and water fastness is more improved. The 
reason for it is considered to be that the alkali metal not contained in 
the dyes acts as a counter ion to the dyes, and some synergistic effect 
thus takes place. 
The present invention will hereinafter be described in more detail by 
preferred embodiments. 
The ink according to the present invention is an ink comprising at least 
two yellow dyes and a liquid medium dissolving or dispersing the dyes 
therein, wherein the ink comprises a dye represented by the following 
general formula (1) in the state of a free acid, and a yellow dye having a 
SO.sub.3 H group as a main solubilizing group in the state of a free acid 
and having its position in the L*a*b* chromaticity diagram at b*=xa* 
(3.ltoreq.x.ltoreq..infin.). 
##STR6## 
In the general formula (1), Ar and Ar.sub.1 are independently an aryl group 
or a substituted aryl group, at least one of which has at least one 
substituent group selected from the group consisting of COOH and COSH, J 
and J.sub.1 are independently a group selected from the group consisting 
of groups represented by the general formulae 
##STR7## 
wherein R.sub.5 is a radical selected from the group consisting of H, 
alkyl groups, substituted alkyl groups, alkoxy groups, halogens, CN, a 
ureido group and NHCOR.sub.6 (R.sub.6 being a radical selected from the 
group consisting of H, alkyl groups, substituted alkyl groups, aryl 
groups, substituted aryl groups, aralkyl groups and substituted aralkyl 
groups), T is an alkyl group, W is a radical selected from the group 
consisting of H, CN, CONR.sub.10 R.sub.11, pyridinium and COOH, (m) is an 
alkylene chain having 2 to 8 carbon atoms, and B is a radical selected 
from the group consisting of H, alkyl groups and COOH, R.sub.1, R.sub.2, 
R.sub.3, R.sub.4, R.sub.10 and R.sub.11 are independently a radical 
selected from the group consisting of H, alkyl groups and substituted 
alkyl groups, L is a divalent organic bonding group, n is 0 or 1, X is a 
carbonyl group or a group selected from the group consisting of groups 
represented by the general formulae 
##STR8## 
in which Z is a group selected from the group consisting of OR.sub.7, 
SR.sub.7 and NR.sub.8 R.sub.9, Y is a radical selected from the group 
consisting of H, Cl, CN and Z, E is a radical selected from the group 
consisting of Cl and CN, and R.sub.7, R.sub.8 and R.sub.9 are 
independently a radical selected from the group consisting of H, alkenyl 
groups, substituted alkenyl groups, alkyl groups, substituted alkyl 
groups, aryl groups, substituted aryl groups, aralkyl groups and 
substituted aralkyl groups, or R.sub.8 and R.sub.9 form a 5- or 6-membered 
ring together with the nitrogen atom to which they are bonded, with the 
proviso that (1) Ar and Ar.sub.1 have at least two groups selected from 
COOH and COSH where they have no SO.sub.3 H group, or (2) Ar and Ar.sub.1 
have groups selected from COOH and COSH of at least the same number as the 
number of SO.sub.3 H groups where they have one or more SO.sub.3 H groups. 
Preferred dyes among the dyes represented by the general formula (1) will 
now be described. 
Dyes represented by the general formula (1), which each have at least one 
SO.sub.3 H group as a water-soluble group and at least the same number of 
COOH groups as the number of SO.sub.3 H groups in the dye, are preferred. 
Dyes represented by the general formula (1), which each have no SO.sub.3 H 
group and contain at least two COOH groups, are preferred. 
Dyes represented by the general formula (1), which each have at least three 
COOH groups, are preferred. 
Preferred dyes represented by the general formula (1) are those of a 
structure that at least one of Ar and Ar.sub.1 has at least one COOH 
group. 
Preferred dyes represented by the general formula (1) are those of a 
structure that Ar and Ar.sub.1 each have at least one COOH group. 
Preferred dyes represented by the general formula (1) are those of a 
structure that Ar and Ar.sub.1 each have at least two COOH groups. 
Preferred dyes represented by the general formula (1) are those of a 
structure that both Ar and Ar.sub.1 are dicarboxyphenyl groups. 
Preferred dyes represented by the general formula (1) are those of a 
structure that X is a group represented by the general formula (5), and Z 
in the general formula (5) is a group selected from the group consisting 
of NHC.sub.2 H.sub.4 OH, N(C.sub.2 H.sub.4 OH).sub.2, NHR (R being an 
alkyl group having 1 to 6 carbon atoms) and a morpholino group. 
Preferred dyes represented by the general formula (1) are those each having 
a counter ion selected from the group consisting of ammonium and 
alkylamino ions. 
Specific examples of particularly preferred dyes represented by the general 
formula (1) are given below, to which, however, the invention is not 
limited. 
##STR9## 
Another dye used in the present invention is a yellow dye having a SO.sub.3 
H group as a main solubilizing group in the state of a free acid and 
having its position in the L*a*b* chromaticity diagram at b*=xa* 
(3.ltoreq.x.ltoreq..infin.). Examples of such a dye include C.I. Direct 
Yellow 86 and C.I. Acid Yellow 36. Preferred yellow dyes are dyes each 
having a symmetrical structure inserted with an organic bonding group, 
with dyes represented by the following general formula (8) in the state of 
a free acid being particularly preferred. 
##STR10## 
wherein A.sub.1 is C.sub.n H.sub.2n+1 or OC.sub.n H.sub.2n+1 (n: an 
integer of 1 to 5), and B.sub.1 is 
##STR11## 
(X.sub.1 :a sulfonic group; X.sub.2 and X.sub.3 : a radical selected from 
the group consisting of carboxyl, hydroxyl and amino groups, and hydrogen, 
at least one of X.sub.2 and X.sub.3 having a SO.sub.3 H group). 
Of the dyes represented by the general formula (8), those in which A.sub.1 
is CH.sub.3, and B.sub.1 is 
##STR12## 
(X.sub.1 having the same meaning as defined above) are preferred taking 
the compatibility with the dyes represented by the general formula (1) 
into consideration. Such a combination is the most preferable combination 
from the overall consideration of the properties of ink such as the water 
fastness and color tone, to say nothing of the reliability as to the 
ejection stability and the like. 
Examples of such yellow dyes include yellow dyes having their position in 
the L*a*b* chromaticity diagram at b*=xa* (3.ltoreq.x.ltoreq..infin.), 
such as C.I. Direct Yellow 86. 
The total content of the dye represented by the general formula (1) and the 
yellow dye in the ink is within a range of from 0.1 to 30% by weight, 
preferably from 0.1 to 10% by weight based on the total weight of the ink. 
When the dye represented by the general formula (1) and the yellow dye are 
used in combination, their proportions in the ink are suitably determined 
without any particular limitation. However, it is preferable to use the 
dye represented by the general formula (1) and the yellow dye in a weight 
ratio ranging from 5:1 to 1:1, preferably from 4:1 to 2:1 taking the 
reliability as to print quality when conducting continuous printing and 
long-term storage stability, and the water fastness, color tone and the 
like into consideration. 
When the dye represented by the general formula (1) and the yellow dye are 
used at such a ratio that a* is near 0, the color tone of red and green, 
which are secondary colors, can also be improved, to say nothing of 
preferable yellow. The use of such a mixed dye according to the present 
invention can better improve the reliability as to print quality when 
conducting continuous printing, long-term storage stability, etc. than 
when producing, for example, a tint of a* being near 0 by using one kind 
of dye. It is hence preferable to use such a mixed dye. 
It is also preferable to select a counter ion to the dye represented by the 
general formula (1) from ammonium and alkylamino ions, and to select a 
counter ion to the yellow dye having a SO.sub.3 H group as a main 
solubilizing group in the state of a free acid and having its position in 
the L*a*b* chromaticity diagram at b*=xa* (3.ltoreq.x.ltoreq..infin.) from 
alkanolamino and alkali metal ions. The reason for this is not clearly 
known, but it may be that the solution stability of the dyes is improved. 
It is further preferable that the ink according to the present invention 
should contain a monovalent alkali metal not contained in the dyes. The 
reason for this is considered to be that since the alkali metal not 
contained in the dyes acts as a counter ion to the dyes, and some 
synergistic effect thus takes place, the balance between reliability and 
water fastness is better improved. 
The content of the monovalent alkali metal in the ink is within a range of 
from 0.01 to 10.0% by weight, preferably from 0.1 to 5% by weight, more 
preferably from 0.1 to 3% by weight. 
The ink according to the present invention preferably has a pH of 9 or 
higher because the pH of 9 or higher is more advantageous to the 
reliability as to the print quality when conducting continuous printing, 
crusting, long-term storage stability, etc. 
The ink according to the present invention contains a volatile base 
component such as ammonia or an alkylamine. Since these base components 
volatilize with time, it is preferable that the ink should contain urea or 
a urea derivative such as ethyleneurea, propyleneurea, thiourea or 
diethylurea as a component for covering up such a loss. The content of 
urea or the urea derivative in the ink is within a range of from 0.01 to 
20% by weight, preferably from 0.1 to 15% by weight. 
In order to improve an evenness of a solid print and a fixing ability, a 
penetrating agent such as alcohol or ether may be contained in the ink. 
The content of the penetrating agent in the ink is within a range of from 
0.01 to 15% by weight, preferably from 0.01 to 10% by weight. 
The liquid medium dissolving or dispersing the dyes therein, which is 
useful in the practice of the present invention, is preferably a mixed 
solvent of water and a water-soluble organic solvent. Specific examples of 
the water-soluble organic solvent include amides such as dimethylformamide 
and dimethylacetamide; ketones such as acetone; ethers such as 
tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene 
glycol and polypropylene glycol; alkylene glycols the alkylene moiety of 
which has 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, 
butylene glycol, triethylene glycol, hexylene glycol and diethylene 
glycol; thiodiglycol; 1,2,6-hexanetriol; glycerol; lower alkyl ethers of 
polyhydric alcohols, such as ethylene glycol monomethyl (or monoethyl) 
ether, diethylene glycol monomethyl (or monoethyl) ether and triethylene 
glycol monomethyl (or monoethyl) ether; N-methyl-2-pyrrolidone; 
1,3-dimethyl-2-imidazolidinone; triethanolamine; sulfolane; 
dimethylsulfoxide; cyclic amide compounds such as 2-pyrrolidone and 
.epsilon.-caprolactam; and imide compounds such as succinimide. 
The content of the water-soluble organic solvent in the ink is preferably 
within a range of generally from 1% to 40% by weight, more preferably from 
3% to 30% by weight, based on the total weight of the ink. 
The content of water in the ink is within a range of from 30 to 95% by 
weight. If the amount of water is less than 30% by weight, the solubility 
and the like of the dyes are deteriorated, and the viscosity of the 
resulting ink is also increased. It is hence not preferable to use water 
in such a small amount. On the other hand, if the amount of water is 
greater than 95% by weight, the vaporizing components are too great to 
sufficiently satisfy the crusting property. 
In order to better improve the solution stability of the dyes in the ink, 
besides the above components, various additives may preferably be 
contained in the ink according to the present invention. More 
specifically, a volatile base component such as ammonia or an alkylamine 
may be contained in the ink without any problem. Besides, urea, urea 
derivatives and other various additives may be contained. Further, salts 
of a strong acid and a strong base, amines and the like may be contained 
as a pH adjustor. Besides the above components, additives such as 
surfactants, rust preventives, mildewproofing agents, antioxidants, 
vaporization accelerators, chelating agents and water-soluble polymers may 
be added as necessary. 
Although the ink according to the present invention may be used as a common 
water-soluble writing utensil, it is particularly suitable for use in an 
ink-jet recording system of the type that an ink is ejected by thermal 
energy. This recording system has the feature that the ejection of the ink 
becomes extremely stable, and no satellite dots are generated. In this 
case, however, the thermal properties (for example, the specific heat, the 
coefficient of thermal expansion, the heat conductivity, etc.) of the ink 
may be controlled in some cases. 
The ink according to the present invention is desirably controlled so as to 
have, as its own physical properties, a surface tension of 30 to 68 
dyn/cm, preferably 30 to 50 dyn/cm and a viscosity of 15 cP or lower, 
preferably 10 cP or lower, more preferably 5 cP or lower as measured at 
25.degree. C. from the viewpoint of solving the problem of water fastness 
of the resulting printed images when recorded on plain paper or the like 
and at the same time, making the matching of the ink with an ink-jet head 
good. 
As a preferred method and apparatus for conducting recording by using the 
ink according to the present invention, may be mentioned an ink-jet 
recording method and apparatus in which thermal energy corresponding to 
recording signals is applied to an ink within a recording head, and the 
ink is ejected by the thermal energy. 
Examples of the construction of a head, which is a main component of such 
an apparatus, are illustrated in FIGS. 1, 2 and 3. 
A head 13 is formed by bonding a glass, ceramic or plastic plate or the 
like having a groove 14 through which an ink is passed, to a heating head 
15, which is used for thermal recording (the drawings show a head to 
which, however, the invention is not limited). The heating head 15 is 
composed of a protective film 16 made of silicon oxide or the like, 
aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 made of 
nichrome or the like, a heat accumulating layer 19, and a substrate 20 
made of alumina or the like having a good heat radiating property. 
An ink 21 comes up to an ejection orifice (a minute opening) 22 and forms a 
meniscus 23 due to a pressure (not illustrated). 
Now, upon application of electric signals to the electrodes 17-1 and 17-2, 
the heating head 15 rapidly generates heat at the region shown by n to 
form bubbles in the ink 21 which is in contact with this region. The 
meniscus 23 of the ink is projected by the pressure thus produced, and the 
ink 21 is ejected from the orifice 22 to a recording medium 25 in the form 
of minute droplets 24. 
FIG. 3 illustrates an appearance of a multi-head composed of an array of a 
number of heads as shown in FIG. 1. The multi-head is formed by closely 
bonding a glass plate 27 having a number of grooves 26 to a heating head 
28 similar to the head as illustrated in FIG. 1. 
Incidentally, FIG. 1 is a cross-sectional view of the head 13 taken along 
the flow path of ink, and FIG. 2 is a cross-sectional view taken along 
line 2--2 in FIG. 1. 
FIG. 4 illustrates an example of an ink-jet recording apparatus in which 
such a head has been incorporated. 
In FIG. 4, reference numeral 61 designates a blade serving as a wiping 
member, one end of which is a stationary end held by a blade-holding 
member to form a cantilever. The blade 61 is provided at a position 
adjacent to a region in which a recording head operates, and in this 
embodiment, is held in such a form that it protrudes into the course 
through which the recording head is moved. Reference numeral 62 indicates 
a cap, which is provided at a home position adjacent to the blade 61, and 
is so constructed that it moves in a direction perpendicular to a 
direction in which the recording head is moved, and comes into contact 
with the face of ejecting openings to cap it. Reference numeral 63 denotes 
an ink-absorbing member provided adjoiningly to the blade 61 and, similar 
to the blade 61, held in such a form that it protrudes into the course 
through which the recording head is moved. The above-described blade 61, 
cap 62 and absorbing member 63 constitute an ejection-recovery portion 64, 
where the blade 161 and absorbing member 63 remove water, dust and/or the 
like from the face of the ink-ejecting openings. 
Reference numeral 65 designates the recording head having an 
ejection-energy-generating means and serving to eject the ink onto a 
recording medium set in an opposing relation to the ejection opening face 
provided with the ejection openings to conduct recording. Reference 
numeral 66 indicates a carriage on which the recording head 65 is mounted 
so that the recording head 65 can be moved. The carriage 66 is slidably 
interlocked with a guide rod 67 and is connected (not illustrated) to a 
belt 69 driven by a motor 68. Thus, the carriage 66 can be moved along the 
guide rod 67 and hence, the recording head 65 can be moved from a 
recording region to a region adjacent thereto. 
Reference numerals 51 and 52 denote a feeding part from which the recording 
media are separately inserted, and feed rollers driven by a motor (not 
illustrated), respectively. With such a construction, the recording medium 
is fed to the position opposite to the ejection opening face of the 
recording head 65, and discharged from a discharge section provided with 
discharge rollers 53 with the progress of recording. 
In the above construction, the cap 62 in the head recovery portion 64 is 
receded from the path of motion of the recording head 65 when the 
recording head 65 is returned to its home position, for example, after 
completion of recording, and the blade 61 remains protruded into the path 
of motion. AS a result, the ejection opening face of the recording head 65 
is wiped. When the cap 62 comes into contact with the ejection opening 
face of the recording head 65 to cap it, the cap 62 is moved so as to 
protrude into the path of motion of the recording head 65. 
When the recording head 65 is moved from its home position to the position 
at which recording is started, the cap 62 and the blade 61 are at the same 
positions as the positions for the wiping as described above. As a result, 
the ejection opening face of the recording head 65 is also wiped at the 
time of this movement. 
The above movement of the recording head 65 to its home position is made 
not only when the recording is completed or the recording head is 
recovered for ejection, but also when the recording head 65 is moved 
between recording regions for the purpose of recording, during which it is 
moved to the home position adjacent to each recording region at given 
intervals, where the ejection opening face is wiped in accordance with 
this movement. 
FIG. 5 illustrates an exemplary ink cartridge 45 in which an ink to be fed 
to the head through an ink-feeding member, for example, a tube is 
contained. Here, reference numeral 40 designates an ink container portion 
containing the ink to be fed, as exemplified by a bag for the ink. One end 
thereof is provided with a stopper 42 made of rubber. A needle (not 
illustrated) may be inserted into this stopper 42 so that the ink in the 
bag 40 for the ink can be fed to the head. Reference numeral 44 indicates 
an ink-absorbing member for receiving a waste ink. It is preferred in the 
present invention that the ink container portion is formed of a 
polyolefin, in particular, polyethylene, at its surface with which the ink 
comes into contact. 
The ink-jet recording apparatus used in the present invention is not 
limited to the apparatus as described above in which the head and the ink 
cartridge are separately provided. Therefore, a device in which these 
members are integrally formed as shown in FIG. 6 can also be preferably 
used. 
In FIG. 6, reference numeral 70 designates a recording unit, in the 
interior of which an ink container portion containing an ink, for example, 
an ink-absorbing member, is contained. The recording unit 70 is so 
constructed that the ink in such an ink-absorbing member is ejected in the 
form of ink droplets through a head 71 having a plurality of orifices. In 
the present invention, polyurethane, cellulose or polyvinyl acetal is 
preferably used as a material for the ink-absorbing member. 
Reference numeral 72 indicates an air passage for communicating the 
interior of the recording unit 70 with the atmosphere. This recording unit 
70 is used in place of the recording head shown in FIG. 4, and is 
detachably installed on the carriage 66. 
The present invention will hereinafter be described in more detail by the 
following Examples and Comparative Examples. Incidentally, all 
designations of "part" or "parts" and "%" as will be used in the following 
examples mean part or parts by weight and % by weight unless expressly 
noted. 
EXAMPLES 1 TO 4 
After their corresponding components described below were mixed and 
thoroughly stirred into solutions, the resultant solutions were separately 
filtered under pressure through a "Fluoropore Filter" (trade name; product 
of Sumitomo Electric Industries, Ltd.) having a pore size of 0.45 .mu.m, 
thereby preparing respective inks according to Examples 1 to 4. These inks 
were adjusted to a pH of about 9.5 
Ink Composition of Example 1: 
______________________________________ 
Acetylenol EH (trade name, product of 
1 part 
Kawaken Fine Chemicals Co., Ltd.) 
Urea 8 parts 
Glycerol 8 parts 
Ethylene glycol 8 parts 
Water 72.1 parts 
C.I. Direct Yellow 86 (x = 7.3) 
0.5 part 
Dye (1) 1.7 parts 
Lithium hydroxide 0.2 part 
Triethanolamine 0.5 part. 
______________________________________ 
(Note) x in the yellow dye means a value of a position of b*=xa* on an 
L*a*b* chromaticity diagram when conducting printing with an ink 
containing the dye at a concentration of 2.5% on paper for copying, 4024 
(trade name, product of Xerox Co.) to measure the chromaticity of the 
resulting print. 
Ink Composition of Example 2: 
______________________________________ 
Ethylene oxide-propylene oxide 
1 part 
copolymer (MH 50, trade name, product 
of Asahi Denka Kogyo K.K.) 
Thiourea 5 parts 
2-Pyrrolidone 8 parts 
Triethylene glycol 8 parts 
Water 74.8 parts 
C.I. Direct Yellow 86 (x = 7.3) 
0.8 part 
Dye (2) 1.7 parts 
Ammonium sulfate 0.3 part 
Sodium hydroxide 0.4 part. 
______________________________________ 
Ink Composition of Example 3: 
______________________________________ 
Acetylenol EH (trade name, product of 
1 part 
Kawaken Fine Chemicals Co., Ltd.) 
Urea 8 parts 
Diethylene glycol 10 parts 
Thiodiglycol 10 parts 
C.I. Direct Yellow 86 (x = 7.3) 
0.5 part 
Dye (3) 1.7 parts 
Water 67.5 parts 
Diethanolamine 0.8 part 
Lithium acetate 0.5 part. 
______________________________________ 
Ink Composition of Example 4: 
______________________________________ 
Acetylenol EH (trade name, product of 
1 part 
Kawaken Fine Chemicals Co., Ltd.) 
Urea 8 parts 
Glycerol 8 parts 
Ethylene glycol 8 parts 
Water 72.1 parts 
C.I. Direct Yellow 86 (x = 7.3) 
0.5 part 
Dye (1) 1.7 parts 
Sodium hydroxide 0.2 part 
Triethanolamine 0.5 part. 
______________________________________ 
Comparative Example 1: 
In the composition of Example 1, Dye (1) was omitted, and instead, purified 
water was supplied to prepare an ink. 
Comparative Example 2: 
In the composition of Example 1, C.I. Direct Yellow 86 (x=7.3) was omitted, 
and instead, purified water was supplied to prepare an ink. 
Comparative Example 3: 
In the composition of Example 1, C.I. Direct Yellow 86 (x=7.3) was omitted, 
and instead, Dye (2) was supplied to prepare an ink. 
Comparative Example 4: 
In the composition of Example 1, Dye (1) was omitted, and instead, C.I. 
Acid Yellow 23 was supplied to prepare an ink. 
Comparative Example 5: 
In the composition of Example 1, Dye (1) and C.I. Direct Yellow 86 (x=7.3) 
were omitted, and instead, C.I. Direct Yellow 142 was supplied to prepare 
an ink. 
&lt;Methods and Standards for Evaluation&gt; 
(1) Evaluation of chromaticity: 
Solid printing was conducted with an ink to be tested on paper for copying, 
4024 (trade name, product of Xerox Co.) to measure a chromaticity of the 
resulting print by means of a high-speed spectrophotometer, CMS-500 Model 
(trade name, manufactured by K.K. Murakami Shikisai Gijutsu Kenkyusho), 
whereby a position on the chromaticity diagram was confirmed to rank the 
chromaticity as AA, A or B in order from that near the neutral position 
(a*=0). 
EQU AA: -2.ltoreq.a*.ltoreq.2, b*.gtoreq.0; 
EQU A: -10.ltoreq.a*.ltoreq.-2, 2.ltoreq.a*.ltoreq.10, b*.gtoreq.0; 
EQU B: a*.ltoreq.-10, 10.ltoreq.a*, b*.gtoreq.0. 
(2) Evaluation of water fastness: 
After an ink to be tested was charged into a printer to print English 
characters and numerals and solid print areas on commercially-available 
acid paper, the printer was stopped and the resulting print sample was 
left over for at least 1 hour, followed by measurement of the Optical 
density of the print by a "Macbeth RD915" (trade name; manufactured by 
Macbeth Company). After the print sample was then immersed for 3 minutes 
in a container filled with water, it was allowed to stand and air-dried to 
measure its optical density again, whereby the percent retention of the 
optical density was determined in accordance with the following equation. 
The water fastness was ranked in accordance with the following standard: 
##EQU1## 
A: Percent retention of optical density not lower than 80%, B: Percent 
retention of optical density not lower than 60% but lower than 80%; 
C: Percent retention of optical density lower than 60%. 
(3) Evaluation of print quality after continuous printing (evaluation of 
durability): 
Continuous printing was conducted with an ink to be tested by a printer for 
24 hours in a thermostatic chamber at 35.degree. C., and the print quality 
after this was visually observed to rank it in accordance with the 
following standard: 
A: Normal printing could be conducted; 
B: Printing could be conducted without problems in actual use though print 
irregularity was somewhat observed; 
C: Ejection failure or print irregularity was observed. 
(4) Evaluation of clogging tendency (recovery property 
from crusting): 
An ink-jet printer, BJC600J (trade name; manufactured by Canon Inc.) 
charged with an ink to be tested was left over for 1 month in a 
thermostatic chamber at 35.degree. C., and then for 24 hours at room 
temperature. After conducting recovery operation (sucking operation by 
pumping), printing was conducted. The clogging tendency was ranked in 
accordance with the following standard: 
A: Normal printing state was recovered by conducting recovery operation at 
most 5 times; 
B: Normal printing state was recovered by conducting recovery operation 6 
to 10 times; 
C: Ejection failure or print irregularity was caused even after conducting 
recovery operation 6 to 10 times. 
(5) Evaluation of long-term storage stability at high temperature: 
An ink to be tested was placed in a hermetically sealed bottle and left 
therein over 3 months in an environment controlled at 50.degree. C. 
Thereafter, the ink sample was filtered through filter paper to evaluate 
the ink as to storage stability by visually observing whether aggregate 
occurred or not and rank it in accordance with the following standard: 
AA: No aggregate was observed; 
A: Aggregate was somewhat observed at a level causing no problem from the 
viewpoint of printing; 
B: Aggregate was somewhat observed, and the resulting print slightly 
blurred; 
C: Aggregate was observed to a great extent, and ejection failure was 
caused. 
(6) Evaluation of long-term storage stability at low temperature: 
An ink to be tested was placed in a hermetically sealed bottle and left 
therein over 3 months in an environment controlled at 5.degree. C. 
Thereafter, the ink sample was filtered through filter paper to evaluate 
the ink as to storage stability by visually observing whether aggregate 
occurred or not and rank it in accordance with the following standard: 
AA: No aggregate was observed; 
A: Aggregate was somewhat observed at a level causing no problem from the 
viewpoint of printing; 
B: Aggregate was somewhat observed, and the resulting print slightly 
blurred; 
C: Aggregate was observed to a great extent, and ejection failure was 
caused. 
The evaluation results as to the above Examples and Comparative Examples 
are shown in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Example Comparative Example 
1 2 3 4 1 2 3 4 5 
__________________________________________________________________________ 
(1) 
Chromaticity 
AA AA AA AA A A A AA AA 
(2) 
Water fastness 
A A A A B A A C C 
(3) 
Print quality after 
A A A A B B B A A 
continuous printing 
(4) 
Clogging tendency 
A A A A A B B A A 
(5) 
Long-term storage at 
AA AA AA AA AA AA AA AA C 
high temperature 
(6) 
Long-term storage at 
AA A AA A AA B B AA A 
low temperature 
__________________________________________________________________________ 
According to the present invention, as described above, there can be 
provided inks which have excellent durability and long-term storage 
stability, can improve the water fastness and color tone of the resulting 
recorded images, and permit recording with high reliability without the 
least problem even when used in an ink-jet recording system. 
According to the ink-jet recording method and apparatus of the present 
invention using the inks described above, recording can be conducted with 
high reliability in that resistance to clogging at orifices is excellent. 
While the present invention has been described with respect to what is 
presently considered to be the preferred embodiments, it is to be 
understood that the invention is not limited to the disclosed embodiments. 
To the contrary, the invention is intended to cover various modifications 
and equivalent arrangements included within the spirit and scope of the 
appended claims. The scope of the following claims is to be accorded the 
broadest interpretation so as to encompass all such modifications and 
equivalent structures and functions.