U.S. patent application number 09/784219 was filed with the patent office on 2001-09-13 for ink, ink set, ink cartridge, recording unit, image recording apparatus and image recording method.
Invention is credited to Hattori, Yoshifumi, Mishina, Shinya, Osumi, Koichi, Sanada, Mikio, Takizawa, Yoshihisa, Teraoka, Hisashi, Yakushigawa, Yuko.
Application Number | 20010020431 09/784219 |
Document ID | / |
Family ID | 27299688 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010020431 |
Kind Code |
A1 |
Osumi, Koichi ; et
al. |
September 13, 2001 |
Ink, Ink set, ink cartridge, recording unit, image recording
apparatus and image recording method
Abstract
Provided is a black ink capable of mitigating the dependency on
image quality of recording media and giving a high quality image
stably, which comprises at least one salt selected from the group
consisting of (M1).sub.2SO.sub.4, CH.sub.3COO(M1), Ph_COO(M1),
(M1)NO.sub.3, (M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3 and
(M1).sub.2CO.sub.3, where M1 is an alkali metal, ammonium or
organo-ammonium and Ph is a phenyl group, and a self dispersible
carbon black.
Inventors: |
Osumi, Koichi;
(Yokohama-shi, JP) ; Hattori, Yoshifumi;
(Yamato-shi, JP) ; Takizawa, Yoshihisa; (Tokyo,
JP) ; Mishina, Shinya; (Kawasaki-shi, JP) ;
Sanada, Mikio; (Yokohama-shi, JP) ; Teraoka,
Hisashi; (Kawasaki-shi, JP) ; Yakushigawa, Yuko;
(Kawasaki-shi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Family ID: |
27299688 |
Appl. No.: |
09/784219 |
Filed: |
February 16, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09784219 |
Feb 16, 2001 |
|
|
|
09271248 |
Mar 17, 1999 |
|
|
|
Current U.S.
Class: |
106/31.6 ;
106/31.75 |
Current CPC
Class: |
C09D 11/38 20130101;
B41J 2/01 20130101; C09D 11/40 20130101 |
Class at
Publication: |
106/31.6 ;
106/31.75 |
International
Class: |
C09D 011/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 20, 1998 |
JP |
10-072224 |
Oct 27, 1998 |
JP |
10-305742 |
Mar 15, 1999 |
JP |
11-068272 |
Claims
What is claimed is:
1. An aqueous ink comprising at least one salt selected from the
group consisting of (M1).sub.2SO.sub.4, CH.sub.3COO(M1),
Ph-COO(M1), (M1)NO.sub.3, (M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3
and (M1).sub.2CO.sub.3, where M1 represents an alkali metal,
ammonium or an organo-ammonium and Ph is a phenyl group, and a self
dispersible carbon black.
2. The ink according to claim 1, wherein the salt is contained in
an amount of from 0.05 to 10% by weight relative to the whole
weight of ink.
3. The ink according to claim 2, wherein the salt is contained in
an amount of from 0.1 to 5% by weight relative to the whole weight
of ink.
4. The ink according to claim 1, wherein the carbon black has at
least one hydrophilic group bonded directly or via another atomic
group to the surface.
5. The ink according to claim 4, wherein the hydrophilic group is
at least one selected from the group consisting of --COO(M2),
--SO.sub.3(M2).sub.2, --PO.sub.3H(M2), PO.sub.3(M2).sub.2,
--NH.sub.3.sup.+, --NR.sub.3.sup.+, --SO.sub.2N.sup.+H.sub.4,
--SO.sub.2N.sup.+H.sub.2COR, 9where M2 in the formulae is a
hydrogen atom, an alkali metal, ammonium or organo-ammonium and R
is an alkyl group having 1 to 12 carbon atoms, a substituted or
unsubstituted phenyl group or substituted or unsubstituted naphthyl
group.
6. The ink according to claim 4, wherein the another atomic group
is an alkylene group having 1 to 12 carbon atoms, a substituted or
unsubstituted phenylene group or substituted or unsubstituted
naphthylene group.
7. The ink according to claim 1, wherein the hydrophilic group is
at least one selected from the group consisting of --COO(M2),
--SO.sub.3(M2).sub.2 and --PO.sub.3H(M2).sub.2 where M2 is the same
as M1.
8. The ink according to claim 1, wherein the ink further comprises
a stabilizer.
9. The ink according to claim 8, wherein the stabilizer is a
surfactant.
10. The ink according to claim 9, wherein the surfactant is an
ionic surfactant.
11. The ink according to claim 8, wherein the stabilizer is
dodecylbenzenesulfonate.
12. The ink according to claim 8, wherein the stabilizer is
contained in an amount of from 0.02 to 0.1% by weight.
13. The ink according to claim 1, wherein the ink has a pH of from
9 to 12.
14. The ink according to claim 13, wherein the ink has a pH of from
9 to 11.
15. The ink according to claim 1, wherein the ink further comprises
an antioxidant.
16. The ink according to claim 15, wherein the antioxidant is
contained in an amount of from 0.02 to 10% by weight.
17. Ink as set forth in claim 15, wherein the antioxidant is at
least one selected from the group consisting of sulfites,
ascorbates and hydrogensulfite.
18. The ink according to claim 1, wherein the ink further comprises
a water-soluble polymer compound.
19. The ink according to claim 18, wherein the water-soluble
polymer compound has a weight average molecular weight of from
1,000 to 5000.
20. The ink according to claim 18, wherein the water-soluble
polymer compound is contained in an amount of from 0.02 to 2% by
weight relative to the whole weight of ink.
21. The ink according to claim 18, wherein the water-soluble
polymer compound is contained in an amount of from 0.1 to 1% by
weight relative to the whole weight of ink.
22. The ink according to claim 1, wherein Ka value measured by the
Bristow method is not more than 1.5.
23. The ink according to claim 22, wherein the Ka value measured by
the Bristow method is within a range of from 0.2 to 1.5.
24. An ink for forming a predetermined optical density of print
image on a recording medium by an ink-jet method, wherein the ink
comprises at least one salt selected from the group consisting of
(M1).sub.2SO.sub.4, CH.sub.3COO(M1), Ph-COO(M1), (M1)NO.sub.3,
(M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3 and (M1).sub.2CO.sub.3,
where M1 is an alkali metal, ammonium or organic ammonium and Ph is
a phenyl group, and a self dispersible carbon black; and wherein
concentration of the carbon black is concentration that the
predetermined optical density of image cannot be obtained in case
that no salt is contained.
25. The ink according to claim 24, wherein a Ka value measured by
the Bristow method is not more than 1.5.
26. The ink according to claim 25, wherein the Ka value by the
Bristow method is within a range of from 0.2 to 1.5.
27. The ink according to claim 24, wherein the carbon black has at
least one hydrophilic group bonded directly or via another atomic
group to the surface.
28. The ink according to claim 27, wherein the hydrophilic group is
at least one selected from the group consisting of --COO(M2),
--SO.sub.3(M2).sub.2, --PO.sub.3H(M2), PO.sub.3(M2).sub.2,
--NH.sub.3.sup.+, --NR.sub.3.sup.+, --SO.sub.2NH.sub.3.sup.+,
--SO.sub.2NH.sub.2.sup.+COR, 10where M2 in the formulae is a
hydrogen atom, an alkali metal, ammonium or organo-ammonium and R
is an alkyl group having 1 to 12 carbon atoms, a substituted or
unsubstituted phenyl group or substituted or unsubstituted naphthyl
group.
29. Ink as set forth in claim 27, wherein the another atomic group
is an alkylene group having 1 to 12 carbon atoms, a substituted or
unsubstituted phenylene group or substituted or unsubstituted
naphthylene group.
30. Ink as set forth in claim 24, wherein the hydrophilic group is
at least one selected from the group consisting of --COO(M2),
--SO.sub.3(M2).sub.2 and --PO.sub.3H(M2).sub.2, where M2 is the
same as M1.
31. An ink set comprising a combination of aqueous ink comprising
at least one coloring material selected from coloring materials for
cyan, for magenta, for yellow, for red, for green and for blue and
the ink according to claim 1 or 24.
32. The ink set according to claim 31, wherein the coloring
material is an acid dye or a direct dye.
33. The ink set according to claim 31, wherein the coloring
material is a pigment.
34. An ink cartridge comprising an ink tank for storing the ink
therein according to claim 1 or 24.
35. A recording unit comprising an ink storing section for storing
the ink according to claim 1 or 24 and a head section for ejecting
the ink.
36. An image recording apparatus comprising: an ink cartridge
having the ink tank for storing ink according to claim 1 or 24, a
recording head for ejecting the ink and supply means for supplying
the ink to the recording head from the ink cartridge.
37. An image recording apparatus comprising an ink storing section
for storing the ink according to claim 1 or 24, and a recording
unit equipped with the head section for ejecting the ink.
38. An image recording apparatus comprising an ink storing section
for storing aqueous ink comprising at least one coloring material
selected from coloring materials for cyan, for magenta, for yellow,
for red, for green and for blue, an ink storing section for storing
the ink according to claim 1 or 24 and head sections for
respectively ejecting the ink stored in individual ink storing
sections.
39. An image recording apparatus comprising an ink cartridge
equipped with an ink storing section for storing aqueous ink
comprising at least one coloring material selected from coloring
materials for cyan, for magenta, for yellow, for red, for green and
for blue, an ink cartridge equipped with an ink storing section for
storing the ink according to claim 1 or 24, head sections for
respectively ejecting the ink stored in individual ink storing
sections, and supply means for supplying individual types of the
ink from the respective ink cartridges to the respective head
sections.
40. An image recording method for ejecting the ink according to
claim 1 or 24 toward a recording medium surface and depositing the
ink to the surface for the recording of an image.
41. The image recording method according to claim 40, wherein
energy for ejecting the ink is thermal energy.
42. The image recording method according to claim 40, wherein
energy for ejecting the ink is mechanical energy.
43. A color image forming method comprising the steps of: ejecting
a first aqueous ink comprising at least one coloring material
selected from coloring materials for cyan, for magenta, for yellow,
for red, for green and for blue toward a surface of a recording
medium and depositing the ink to the surface; and ejecting a second
ink according to any one of claims 1 to 24 toward a surface of a
recording medium and depositing the ink to the surface.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an ink, an ink set, an ink
cartridge, a recording unit, an image recording apparatus and an
image recording method.
[0003] 2. Related Background Art
[0004] Hitherto, as a black ink for writing implements such as
fountain pen, sign pen or ball-point pen and a black ink for an
ink-jet printer, an ink using carbon black, a black colorant, high
in optical density of image and excellent in fastness has been
proposed. Especially in recent years, a detailed research and
development has been made from diverse aspects such as composition
and property of the ink, so as to perform a good recording even on
plain paper such as copy paper used generally in offices, report
paper, notebook paper, letter paper, bond paper and serial slip
paper. For example, Japanese Patent Application Laid-Open Nos.
61-283875 and 64-6074 disclose a water-based pigment ink containing
carbon black and a dispersant. Besides, Japanese Patent Application
Laid-Open No. 8-3498 mentions technical problems that ejection
becomes unstable and no sufficient printing density cannot be
obtained when an ink containing carbon black together with a
dispersant is used as ink for ink-jet printer, and it discloses a
water-based pigment ink comprising a self dispersible carbon black
using no dispersant as an ink capable of solving such problems.
SUMMARY OF THE INVENTION
[0005] The present inventors have made various examinations on
cases of using a black ink containing the above self dispersible
carbon black as a black pigment for ink-jet recording. As a result,
it has been found a case that insufficient character quality or
insufficient image density is obtained depending on types of
recording media such as paper and the like.
[0006] Besides, in printing color images by using such a black ink
as mentioned above together with other color ink such as at least
one color ink selected from magenta ink, cyan ink, yellow ink, red
ink, green ink and blue ink, there has been recognized a phenomenon
that an image quality is lowered by blotting of ink at the boundary
between the black image portion and the color image portion on a
recording medium and by non-uniform mix of ink (hereinafter,
referred to as "bleeding").
[0007] In order to prevent or reduce such bleeding, an idea of
promoting the permeability of ink into recording media by addition
of a so-called surfactant (such as, e.g. Japanese Patent
Application Laid-Open No. 55-65269) or an idea of mainly employing
volatile solvent as a solvent of ink (such as, e.g. Japanese Patent
Application Laid-Open No. 55-66976) has been proposed. Also with
these background techniques, however, a decrease in optical density
of image and a decrease in ejection stability were brought about in
some cases. In consideration of such background techniques, the
present inventors have found that it is necessary to develop a
black ink hardly changing in image quality even when types of
recording media may be varied, in a case using the ink singly or a
combination thereof with other color ink, with respect to an ink
comprising a self dispersible carbon black as black pigment.
[0008] It is one object of the present invention to provide a black
ink capable of mitigating an influence of recording media to an
image quality and providing a black ink which can provide a high
quality image stably.
[0009] It is one object of the present invention to provide a black
ink capable of mitigating an influence of recording media to an
image quality and providing a black ink which can provide a high
quality image stably and is excellent in ink-jet ejection
characteristics.
[0010] It is another object of the present invention to provide an
ink set capable of effectively inhibiting the bleeding. Especially,
because a black ink is often used for outputting characters or the
like, a high OD (optical density) and a large difference in
sharpness of characters are strongly required. Thus, in a technical
skill for preventing the bleeding by using highly permeable ink as
mentioned above, both character quality grade and OD have not yet
been satisfied at a high level. It is also an object of the present
invention to satisfy both character quality grade and OD at a
higher level.
[0011] Furthermore, it is a further object of the present invention
to provide an image recording apparatus and an image recording
method, capable of mitigating an influence of recording media to an
image quality and providing a high quality image stably, and
moreover an ink cartridge and a recording unit used for them.
[0012] The above objects can be achieved by the present invention
described below.
[0013] According to a first aspect of the present invention, there
is provided an aqueous ink comprising at least one salt selected
from the group consisting of (M1).sub.2SO.sub.4, CH.sub.3COO(M1),
Ph-COO(M1), (M1)NO.sub.3, (M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3
and (M1).sub.2CO.sub.3, where M1 is an alkali metal, ammonium or
organo-ammonium and Ph means a phenyl group, and a self dispersible
carbon black.
[0014] According to this embodiment, a high grade image can be
formed even in the character printing on highly permeable paper
which may cause damaging an image grade, such as sharpness of
characters, or lowering the image density. Incidentally, the reason
why such an effect is obtained according to this embodiment is
obscure, but is attributable to a rapid occurrence of solid-liquid
separation after deposited to the paper surface in contrast to the
stable dispersion of pigments in ink, for example when the ink is
ejected and deposited to paper surface by the ink jet method. In
other words, a slow solid-liquid separation allows ink to diffuse
all over the paper for paper having a high permeability. As a
result, a decrease in optical density of image as well as damages
on the sharpness of characters (character quality grade) is
naturally derived from a permeation of ink into the depth of paper.
Since a solid-liquid separation occurs rapidly in paper according
to this embodiment, however, the above phenomenon is considered to
become difficult to occur for paper relatively high in
permeability. In brief, it is considered to become insusceptible to
factors such as degree of permeability dependent on the type of
paper. And such an effect seems to be best obtained for 0.05 to 10%
by weight of salts relative to the whole weight of ink.
Furthermore, sulfates such as potassium sulfate or benzoates such
as ammonium benzoate slightly affect the characteristics of the
above ink, e.g. in use for ink-jet printing.
[0015] Besides, as another example of ink according to this
embodiment, an ink comprising a self dispersible carbon black, on
the surface of which at least one selected from --COO(M2),
--SO.sub.3(M2).sub.2 and --PO.sub.3H(M2) is bonded directly or via
other atomic groups, and a salt in which M1 and M2 are identical is
mentioned. On account of its still better stability, this is one of
the preferred embodiments. With M2 of ammonium (NH.sub.4), for
example, addition of an ammonium salt, e.g. ammonium benzoate, as a
salt to ink can further improve the water fastness or the like of
ink-jet recording images obtained.
[0016] Besides, as another embodiment of the above ink, ink the pH
of which is set to 9 to 12 can be mentioned, and the ink is also
employed appropriately in stably obtaining a high grade image.
Namely, a knowledge about the above ink that a long-period
preservation brings about an acidic shift of pH, leading to various
changes in characteristics such as an increase in viscosity of ink,
has been obtained. And, a further examination on this point
revealed a new knowledge that a change in characteristics of ink
becomes extremely slow when the pH of ink is set within the above
range and a change in characteristics accompanying the ink pH
change during the preservation becomes as slight as substantially
negligible. And, the above invention is based on such the
knowledge.
[0017] And as a still another embodiment of the above ink, those
coexistent with an stabilizer selected from anionic surfactant,
cationic surfactant and the like, for example, can be mentioned.
Such a composition permits a change in the characteristics of ink
accompanying the pH change of ink to be mitigated. The reason for
such an effect is obscure, but the stabilizer seems to hinder the
mutual contact (collision) between the particles of carbon black,
thus resulting in an extension of the pH range within which ink can
stably exist. And, such an effect is significant especially in use
of alkylbenzenesulfonate as a stabilizer. As one preferred
embodiment, ink so prepared within a pH range of 9 to 12 with
addition of a stabilizer is mentioned. This embodiment displays
both effects of inhibiting a change in pH during the preservation
of ink and preventing a radical change in characteristics
accompanying the pH change. Furthermore, the added amount of a
stabilizer can be lowered and a possibility of ink characteristics
changing can be almost eliminated.
[0018] Besides, as a still further embodiment of the present
invention, the addition of an antioxidant to ink according to
various embodiments mentioned above is mentioned. Use of it can
inhibit a chemical change during the long-period preservation of
ink and a change in the ejection property of ink-jet printing.
[0019] Still further, as another embodiment of the present
invention, the addition of a water-soluble polymer compound to
according to various embodiments mentioned above is mentioned. Use
of it is effective in promoting the frictional resistance of the
recording medium for recording on the ink-deposited surface of
recording medium such as paper.
[0020] According to further aspect of the present invention, there
is also provided an ink for forming a predetermined optical density
of print image on a recording medium by an ink-jet method, wherein
said ink comprises at least one salt selected from the group
consisting of (M1).sub.2SO.sub.4, CH.sub.3COO(M1), Ph-COO(M1),
(M1)NO.sub.3, (M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3 and
(M1).sub.2CO.sub.3, where M1 is an alkali metal, ammonium or
organic ammonium and Ph is a phenyl group, and a self dispersible
carbon black; and wherein concentration of said carbon black is
concentration that the predetermined optical density of image
cannot be obtained in case that no salt is contained.
[0021] According to further aspect of the present invention, there
is also provided an ink set comprising a combination of an aqueous
color ink comprising at least one coloring material selected from
color materials for cyan, for magenta, for yellow, for red, for
green and for blue and an aqueous ink comprising at least one salt
selected from (M1).sub.2SO.sub.4, CH.sub.3COO(M1), Ph-COO(M1),
(M1)NO.sub.3, (M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3 and
(M1).sub.2CO.sub.3 and a self dispersible carbon black, where M1 is
an alkali metal, ammonium or an organo-ammonium and Ph means a
phenyl group.
[0022] When color images are formed using the ink set, the bleeding
at the boundary area between an image formed with ink containing
carbon black and an image formed with ink containing other coloring
materials can be effectively inhibited. The reason for such an
effect obtained according to this embodiment is obscure, but a
rapid solid-liquid separation on the recording medium surface seems
to be related with this effect.
[0023] According to further aspect of the present invention, there
is further provided an ink cartridge equipped with an ink tank
containing a water-based color ink comprising at least one salt
selected from (M1).sub.2SO.sub.4, CH.sub.3COO(M1), Ph-COO(M1),
(M1)NO.sub.3, (M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3 and
(M1).sub.2CO.sub.3 and a self dispersible carbon black.
[0024] According to further aspect of the present invention, there
is provided a recording unit equipped with an ink container
containing a water-based ink comprising at least one salt selected
from (M1).sub.2SO.sub.4, CH.sub.3COO(M1), Ph-COO(M1), (M1)NO.sub.3,
(M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3 and (M1).sub.2CO.sub.3,
and a self dispersible carbon black; and a head section for
ejecting the ink.
[0025] According to further aspect of the present invention, there
is provided an image recording apparatus comprising an ink
cartridge equipped with an ink tank containing an aqueous ink
comprising at least one salt selected from (M1).sub.2SO.sub.4,
CH.sub.3COO(M1), Ph-COO(M1), (M1)NO.sub.3, (M1)Cl, (M1)Br, (M1)I,
(M1).sub.2SO.sub.3 and (M1).sub.2CO.sub.3, and a self dispersible
carbon black; a recording head for ejecting the ink; and supply
means for supplying the ink from the ink cartridge to the recording
head.
[0026] According to further aspect of the present invention, there
is provided an image recording apparatus comprising a recording
unit equipped with an ink holding section for holding an aqueous
ink comprising at least one salt selected from (M1).sub.2SO.sub.4,
CH.sub.3COO(M1), Ph-COO(M1), (M1)NO.sub.3, (M1)Cl, (M1)Br, (M1)I,
(M1).sub.2SO.sub.3 and (M1).sub.2CO.sub.3 and a self dispersible
carbon black; and a head section for ejecting the ink.
[0027] According to further aspect of the present invention, there
is provided an image recording apparatus comprising an ink
container holding an aqueous ink comprising at least one coloring
material selected from coloring materials for cyan, for magenta,
for yellow, for red, for green and for blue; an ink container
holding an aqueous ink comprising at least one salt selected from
(M1).sub.2SO.sub.4, CH.sub.3COO(M1), Ph-COO(M1), (M1)NO.sub.3,
(M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3 and (M1).sub.2CO.sub.3,
and a self dispersible carbon black; and a head section for
respectively ejecting the inks held in the respective ink holding
sections.
[0028] According to further aspect of the present invention, there
is provided an image recording apparatus comprising an ink
cartridge equipped with an ink container portion holding an aqueous
ink comprising at least one coloring material selected from
coloring materials for cyan, for magenta, for yellow, for red, for
green and for blue, an ink cartridge equipped with an ink container
portion holding an aqueous ink comprising at least one salt
selected from (M1).sub.2SO.sub.4, CH.sub.3COO(M1), Ph-COO(M1),
(M1)NO.sub.3, (M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3 and
(M1).sub.2CO.sub.3, and a self dispersible carbon black; a head
section for respectively ejecting the ink held in the respective
ink cartridges; and supply means for supplying the respective ink
from the respective ink cartridges to the respective head
sections.
[0029] According to further aspect of the present invention, there
is provided an image recording method comprising the steps of:
ejecting an aqueous ink comprising at least one salt selected from
(M1).sub.2SO.sub.4, CH.sub.3COO(M1), Ph-COO(M1), (M1)NO.sub.3,
(M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3 and (M1).sub.2CO.sub.3,
and a self dispersible carbon black, toward a recording medium; and
depositing the ink to a surface of the recording medium, thereby
recording images.
[0030] According to further aspect of the present invention, there
is provided an image recording method comprising the steps of:
ejecting a first aqueous ink comprising at least one coloring
material selected from coloring materials for cyan, for magenta,
for yellow, for red, for green and for blue, toward a recording
medium and depositing the ink to a surface of the recording medium;
ejecting a second aqueous ink comprising at least one salt selected
from (M1).sub.2SO.sub.4, CH.sub.3COO(M1), ph-COO(M1), (M1)NO.sub.3,
(M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3 and (M1).sub.2CO.sub.3,
and a self dispersible carbon black toward a recording medium and
depositing the ink to a surface of the recording medium.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a longitudinal cross-sectional view of a head of
an ink-jet recording apparatus according to an embodiment of the
present invention.
[0032] FIG. 2 is a transverse cross-sectional view taken along line
2-2 in FIG. 1.
[0033] FIG. 3 schematically illustrates a multi-head.
[0034] FIG. 4 is a schematic perspective view illustrating an
ink-jet recording apparatus according to an embodiment of the
present invention.
[0035] FIG. 5 is a longitudinal cross-sectional view of an ink
cartridge according to an embodiment.
[0036] FIG. 6 is a perspective view illustrating an ink-jet
recording unit according to an embodiment.
[0037] FIG. 7 is a schematic perspective view illustrating another
exemplary construction of an ink-jet recording head.
[0038] FIG. 8 schematically illustrates a recording head in which 4
ink cartridges are installed.
[0039] FIG. 9 schematically illustrates the construction that 4
recording heads are arranged on a carriage.
[0040] FIG. 10 is a graph roughly illustrating a relation between a
viscosity and a pH of the ink according to an embodiment of-the
present invention.
[0041] FIGS. 11A, 11B and 11C are drawings illustratively showing a
course of solid-liquid separation when a pigment ink comprising a
salt is applied to a recording medium.
[0042] FIGS. 12A, 12B and 12C are drawings illustratively showing a
course of solid-liquid separation when a pigment ink comprising no
salt is applied to a recording medium.
[0043] FIG. 13 is a graph showing a relation between a pigment
concentration in ink and an optical density of images recorded by
an ink comprising a slat and an ink comprising no salt.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] First Embodiment:
[0045] Ink according to one embodiment of the present invention has
one feature in comprising a self dispersible carbon black as one
coloring material and further a salt. And, these constitute an ink,
dispersed or dissolved, e.g., in an aqueous medium.
[0046] (Self dispersible carbon black and Salt)
[0047] As a self dispersible carbon black, the coloring material
for an ink, carbon black, on the surface of which at least one
hydrophilic group directly or via other atomic groups is bonded, is
mentioned. Its use eliminates the need for a dispersant to have
formerly been added for the dispersion of carbon black
particles.
[0048] As salts, it is preferable to use at least one selected from
the group consisting of (M1).sub.2SO.sub.4, CH.sub.3COO(M1),
Ph-COO(M1), (M1)NO.sub.3, (M1)Cl, (M1)Br, (M1)I, (M1).sub.2SO.sub.3
and (M1).sub.2CO.sub.3. Here, M1 is an alkali metal, ammonium or an
organo-ammonium and Ph means a phenyl group. And, specific examples
of alkali metals include Li, Na, K, Rb, Cs and the like, while
specific ones of organo-ammoniums include methyl ammonium, dimethyl
ammonium, trimethyl ammonium, ethyl ammonium, diethyl ammonium,
triethyl ammonium, trimethanol ammonium, dimethanol ammonium,
trimethanol ammonium, ethanol ammonium, diethanol ammonium and
triethanol ammonium.
[0049] Like this, by allowing salts as mentioned above to coexist
in ink comprising a self dispersible carbon black, stable ink not
greatly varying in image quality with different types of recording
media can be obtained to form a high quality image. The detailed
mechanism that the ink according to this embodiment displays such
the characteristics is not clear presently. However, it has been
found out by the present inventors with respect to a Ka value
obtained by the Bristow method, known as a measure indicating the
permeability of ink to a recording medium, that the claimed ink
indicates a higher Ka value than that of an ink having the same
composition except for the content of salts. An increase in Ka
value represents a promoted permeability of ink to a recording
paper and a promoted permeability of ink signifies a decrease in an
optical density of image as common knowledge of those skilled in
the art. Namely, it is a common knowledge of those skilled in the
art that not only ink but also coloring materials permeate into a
recording medium, thus resulting in a decrease in optical density
of image. And, comprehensively judging from such various knowledges
about ink, a salt in ink according to the present invention seems
to induce a specific action of very rapidly causing the separation
of the solvent and the solid component (solid-liquid separation) in
ink after given on a paper surface. In other words, if the
solid-liquid separation in ink given onto a recording medium is
slow, it is presumed that ink great in Ka value or ink on paper
high in permeability is dispersed isotopically throughout the paper
together with coloring materials, thereby resulting in damages on
the sharpness of characters (character quality grade) and at the
same time coloring materials permeate into the depth of paper,
thereby resulting in a decrease of an optical density of image.
However, since such a phenomenon cannot be observed in the ink
according to this embodiment, solid-liquid separation rapidly
occurs in case of given on a recording medium. As a result, an
image of high quality can be formed in spite of an increase in a Ka
value of ink. Besides, the reason why a phenomenon such as
deterioration of character quality grade and lowering of optical
density of image hardly takes place with ink according to the
present invention even for paper relatively high in permeability is
considered to be the same as this. Hereinafter, this point will be
described referring to FIGS. 11A to 11C and 12A to 12C.
[0050] FIGS. 11A to 11C and FIGS. 12A to 12C are illustrations
schematically and conceptually showing the manner of a solid-liquid
separation occurring in respectively ejecting the salt-contained
ink and the salt-free ink from orifices by the ink-jet recording
method and giving them to a recording medium high in permeability.
Namely, directly after the an ink is impacted, a pigment ink 1101
or 1201 is in a status of being placed on a surface of paper 1103
or 1203 regardless of whether with or without addition of salts for
both cases of ink as shown in FIG. 11A and FIG. 12A. After the
lapse of time T1 for the salt-contained pigment ink, solid-liquid
separation occurs rapidly, is almost separated into the area 1105
containing the solid component in abundance from the solvent in ink
and the permeation front 1107 of the separated solvent advances to
the interior of a solvent paper 1103 as shown in FIG. 11B. On the
other hand, because of being not so rapid in solid-liquid
separation as with the salt-contained ink, the salt-free pigment
ink permeates into the interior of the paper 1203 in an unseparated
status 1205 as shown in FIG. 12B. After the lapse of time T2 for
the salt-contained ink, the permeation front 1107 of solvent
further permeates in the interior but the area 1105 is retained to
remain at and near the surface of paper as shown in FIG. 11C. On
the other hand, for the salt-free ink, solid-liquid separation just
occurs at this point of time, as shown in FIG. 12C, a difference
begins to appear between the permeation front 1207 of the solid
portion and that 1209 of the solvent, but the solid component
contained area 1211 reaches the depth of the recording medium.
Incidentally, the time T1 and time T2 in the above description are
measures for conceptually understanding a difference of
solid-liquid separation between the salt-contained and the
salt-free. As clear from the above description, the above effect is
presumed to originate in the fact that addition of salts permits
solid-liquid separation to occur rapidly, thus resulting in the
permeation into the depth of paper as well as the solid-liquid
separation at a relatively earlier stage after the impaction of the
ink. Namely, addition of salts is considered to make the image
grade insusceptible to the degree of permeability in recording
medium. And, among the salts mentioned above, sulfates such as,
e.g. potassium sulfate and benzoates such as, e.g. ammonium
benzoate permit ink-jet record images superior especially in
quality to be formed on various recording media probably because of
their good affinity to a self dispersible carbon black,
specifically excellent solid-liquid separation in case of given to
a recording medium.
[0051] The content of a self dispersible carbon black in ink is
preferably set to the range of from 0.1 to 15% by weight,
especially from 1 to 10% by weight relative to the whole weight of
ink, while that of salts is preferably set to the range of from
0.05 to 10% by weight, especially from 0.1 to 5% by weight. By
setting the contents of a self dispersible carbon black and salts
to the respective ranges mentioned above, a still better effect can
be enjoyed.
[0052] (Self dispersible carbon black)
[0053] Next, a self dispersible carbon black will be described in
detail.
[0054] As a self dispersible carbon black, anionic ones are
preferable and carbon black (CB) charged anionically or
cationically can be suitably used.
[0055] (Anionically charged CB)
[0056] As anionically charged carbon black, those of a hydrophilic
group, e.g. as shown below combined with the surface of carbon
black can be mentioned: --COO(M2), --SO.sub.3(M2).sub.2,
--PO.sub.3H(M2) and --PO.sub.3(M2).sub.2.
[0057] In the formulae mentioned above, M2 represents a hydrogen
atom, an alkali metal, ammonium or an organo-ammonium and R
represents a C.sub.1-C.sub.12 alkyl group, a substituted or
unsubstituted phenyl group or a substituted or unsubstituted
naphthyl group. Among these, especially carbon black anionically
charged by combining --COO(M2) or --SO.sub.3(M2) with the surface
thereof can especially preferably be used for this embodiment
because of being good in dispersibility. Meanwhile, among those
represented by M2, specific examples of alkali metals include Li,
Na, K, Rb, Cs and the like, while specific ones of organo-ammoniums
include methyl ammonium, dimethyl ammonium, trimethyl ammonium,
ethyl ammonium, diethyl ammonium, triethyl ammonium, methanol
ammonium, dimethanol ammonium, trimethanol ammonium and the like.
And, ink according to this embodiment comprising a self dispersible
carbon black in which M2 is ammonium or organo-ammonium employed
can rather promote the water fastness of recorded images and is
preferably usable from this point of view. This is attributable to
the effect of ammonium decomposed and evaporated when the ink is
applied to the surface of a recording medium. Here, the self
dispersible carbon black in which M2 is ammonium can be obtained
by, for example, a method to substitute ammonium for an alkali
metal of a self dispersible carbon black in which M2 is an alkali
metal by means of an ion exchange process, a method to make it to a
H-type (free acid type) by adding an acid and then adding ammonium
hydroxide to make M2 to an ammonium salt, or the like.
[0058] Examples of methods for manufacturing anionically charged
self dispersible carbon black include a method to perform an
oxidation treatment of carbon black with sodium hypochlorite, by
which a --COONa group can be chemically bonded to the surface of
carbon black.
[0059] (Cationically charged Carbon Black)
[0060] As cationically charged carbon black, those bonded with at
least one selected from the quaternary ammonium groups shown below
on the surface of carbon black can be mentioned:
--N.sup.+H.sub.3, --N.sup.+R.sub.3, --SO.sub.2N.sup.+H.sub.3,
--SO.sub.2N.sup.+H.sub.2COR,
[0061] 1
[0062] wherein R represents a straight or branched alkyl group
having 1 to 12 carbon atoms, a substituted or unsubstituted phenyl
group or a substituted or unsubstituted naphthyl group.
Aforementioned quaternary ammonium groups have counter anions such
as NO.sub.3.sup.-, CH.sub.3COO.sup.-, etc., respectively.
[0063] As a method to prepare a cationically charged self
dispersible carbon black bonded with a hydrophilic group, there
will be explained a method in which an N-ethylpyridyl 2
[0064] is bonded.
[0065] A process to treat carbon black with 3-amino-N-ethyl
pyridinium bromide is mentioned. Because of being excellent in
water dispersibility due to the repulsion of ions, the carbon black
anionically or cationically charged by introducing a hydrophilic
group onto the surface thereof retains a stable dispersion state
without addition of a dispersant also for its content in ink.
[0066] Meanwhile, various hydrophilic groups as mentioned above may
be bonded directly to the surface of black carbon, or may be
indirectly bonded with another atomic group laid between the
surface and the hydrophilic group. Here, specific examples of
another atomic groups include a straight or branched alkylene group
having 1 to 12 carbon atoms, substituted or unsubstituted phenylene
groups and substituted or unsubstituted naphthylene groups. Here,
examples of the substituents of the phenylene group and naphthylene
group include a straight or branched alkylene group having 1 to 6
carbon atoms. Besides, specific examples of combinations of the
another atomic groups and the hydrophilic groups include
--C.sub.2H.sub.4--COOM, -Ph-SO.sub.3M and Ph-COOM, where Ph means a
phenyl group and M is an alkaline metal.
[0067] Meanwhile, in this embodiment, two or more self dispersible
carbon blacks may be appropriately selected from the above types
for coloring materials of ink. Besides, the content of a self
dispersible carbon black is preferably set to the range of from 0.1
to 15% by weight, in particular from 1 to 10% by weight relative to
the whole weight of ink. By choosing this range, a self dispersible
carbon black can retain a sufficient dispersion state in ink.
Furthermore, in order to adjust the color tone of ink, dyes may be
added to ink as coloring materials in addition to the self
dispersible carbon black.
[0068] (Affinity between a self dispersible carbon black and
salts)
[0069] In case of using --COO(M2), --SO.sub.3(M2).sub.2,
--PO.sub.3H(M2) or --PO.sub.3(M2).sub.2, for example, as
hydrophilic group at the surface of a self dispersible carbon black
among the above various types of a self dispersible carbon black, a
preferable availability of ammonium or organo-ammoniums as M2 is as
mentioned above, but bringing M1 into coincidence with M2 is
preferable as salts employed at this time. Namely, it has been
found out by the present inventors in the course of examining the
effect of adding a salt to ink comprising a self dispersible carbon
black that the stability of ink is enhanced especially on making M2
(counter ion) identical with M1 in hydrophilic groups. The reason
for such an effect obtained by matching M1 with M2 is obscure, but
is inferred from a dispersion stability of a self dispersible
carbon black retained securely by the absence of salt exchange
between the counter ion of the hydrophilic group of a self
dispersible carbon black and the salt in ink.
[0070] The use of ammonium or organo-ammonium for both M1 and M2
can realize further improvement in water fastness of a recorded
image in addition to a stabilization effect on the ink
characteristics. When Ph-COONH.sub.4 (ammonium benzoate) is then
employed as a salt in ink, an excellent result can be obtained in
terms of re-ejection characteristics of ink from a head nozzle
after suspension of ink jet recording.
[0071] (Aqueous medium)
[0072] An example of aqueous media used in ink according to this
embodiment is water or a mixture comprising water and a
water-soluble organic solvent. As water-soluble organic solvent,
those being effective in preventing the drying of ink are in
particular preferable. Specific examples include
C.sub.1-C.sub.4alkyl alcohols such as methyl alcohol, ethyl
alcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol,
sec-butyl alcohol, and tert-butyl alcohol; amides such as dimethyl
formaldehyde and dimethyl acetamide; ketones or ketoalcohols such
as acetone and diacetone alcohol; ethers such as tetrahydrofurane
and dioxane; polyalkylene glycols such as polyethylene glycol and
polypropylene glycol; alkylene glycols with a
C.sub.2-C.sub.6-alkylene group such as ethylene glycol, propylene
glycol, butylene glycol, triethylene glycol, hexylene glycol and
diethylene glycol; 1,2,6-hexane triol, thiodiglycol; lower alkyl
ether acetates such as polyethylene glycol monomethylether acetate;
glycerol; lower alkyl ethers of polyhydric alcohols such as etylene
glycol monomethyl- (or monoethyl-)ether, dietylene glycol methyl-
(or ethyl-) ether and trietylene glycol monomethyl- (or
monoethyl-)ether; polyhydric alcohols such as trimethylol propane
and trimethylol ethane; N-methyl-2-pyrrolidene, 2-pyrrolidone and
1,3-dimethyl-2-imidazolidinone. Such water-soluble organic solvents
may be used simply or as mixture.
[0073] Besides, use of demineralized water is desired.
[0074] The content of water-soluble organic solvents in ink
according to this embodiment is not especially limited, but lies
preferably within the range of from 3 to 50% by weight relative to
the whole weight of ink. Besides, the content of water in ink lies
preferably within the range of from 50 to 95% by weight.
[0075] As described above, the ink according to the first aspect of
the present invention can exhibit a significant effect that the
dependence of print quality on recording media's chracteristics can
be reduced. In addition, the ink according to the first aspect of
the present invention can show further significant technical
effect. Namely, as to the ink of the present invention and a
reference ink whose contents are identical except that no salt is
contained. FIG. 13 shows a relation between the respective inks'
pigment concentration and optical density of images formed with the
respective inks. As shown in FIG. 13, the optical density of the
respective images saturate in the end, and the present inventors
have found the fact that the optical density of the image according
to the present ink (line (a) of FIG. 13) saturates at lower pigment
concentration than the pigment concentration of the reference ink
which the optical density of the image according to the reference
ink saturates. That is to say, by adding a salt to the ink, the
pigment concentration of the ink can be reduced without changing
the optical density of the image. For example, when a self
dispersible carbon black concentration is varied as to an ink
containing 1% by weight of ammonium benzoate, the optical density
of the image saturates at about 1.4 when the concentration is set
at about 4% by weight, and the optical density does not change any
more even if the concentration is incresed. On the contrary,
salt-free inks whose concentration of the self dispersible carbon
black is set at about 4% by weight and 7% by weight provide prints
having optical densities of about 1.32 and 1.35, respectively.
Further, even though the concentration is set at about 8% by
weight, the optical density keeps the value of about 1.35.
Therefore, for the salt-free ink, the saturated value of the
optical density is considered to be 1.35. The difference between
the saturated values in optical density is numerically slight as
0.05 which is a difference between 1.40 and 1.35, but the
difference between the images is conspicuous.
[0076] As stated above, the salt added inks of the present
invention can provide a print having a high optical density at
relatively low carbon black concentration in comparison with the
salt-free inks, and also the saturated value in an optical density
of the image according to the present ink is higher than that
according to the salt-free inks. Thus, the present ink brings
favorable and unexpected effects in ink-jet printing.
[0077] This also provides the following advantage. That is, ink
comprising a salt has such characteristics that it has a wide
margin for carbon black concentrations with respect to optical
density of printing, as mentioned above. Thus, when an ink tank
containing an absorbent is filled with this ink, left in the same
posture over a long period of time (for example, it is left to keep
its nozzle on the upside for 6 months), and then employed for
printing, it can be prevented very effectively to cause a
visually-detectable difference in optical density between printings
obtained in the initial phase of printing and those obtained
immediately before the ink in the ink tank is used up.
[0078] As a still another effect of addition of salts in ink
according to this embodiment, the excellence in intermittent
ejection property is mentioned. The intermittent ejection property
means estimation of whether ink is normally ejected or not with
eyes laid to a definite nozzle of the recording head when ink is
again ejected from the nozzle on standing for a predetermined time
without spare ejecting or sucking the ink remaining in the nozzle
after ejecting ink from the nozzle.
[0079] (Second embodiment)
[0080] As a second embodiment according to the present invention,
for example, an embodiment with a stabilizer further added to the
ink described above as the first embodiment can be mentioned. Here,
as stabilizer, a surfactant can be mentioned, for example. Besides,
as surfactant, one selected from anionic, nonionic and cationic
surfactants can be employed. And, if the content of stabilizers in
ink is set to 0.005 to 0.4% by weight, in particular to 0.02 to
0.2% by weight relative to the whole weight of ink, the
preservation stability of ink can be further promoted and moreover
the ejecting characteristics or the like of ink is hardly affected.
Furthermore, application of this technique hardly affects the
effect obtained in ink according to the first embodiment,
especially by making M1 and M2 into an identical group, e.g.
ammonium.
[0081] (Anionic surfactant)
[0082] Examples of anionic surfactants include higher fatty acid
salts, higher alkyldicarboxylates, sulfuric acid ester salts of
higher alcohols, higher alkyl-sulfonates, alkylbenzenesulfonates,
alkylnaphthalene sulfonates, naphthalene sulfonates (Na, K, Li, Ca,
etc.), formalin polycondensates, condensates between higher fatty
acids and amino acids, dialkylsulfosuccinic acid ester salts,
alkylsulfosuccinates, naphthenates, alkylether carboxylates,
acylated peptides, .alpha.-olefine sulfonates, N-acrylmethyl
taurine, alkylether sulfonates, secondary higher alcohol
ethoxysulfates, polyoxyethylene alkylphenylether sulfates,
monoglycylsulfates, alkylether phosphates and alkyl phosphates and
the like.
[0083] (Cationic surfactants)
[0084] Examples of cationic surfactants include aliphatic amines,
quaternary ammonium salts, sulfonium salts, phosphonium salts and
the like.
[0085] (Nonionic surfactants)
[0086] Examples of nonionic surfactants include fluorine
derivatives, silicone derivatives, acrylic acid copolymers,
polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether,
polyoxyethylene secondary alcohol ether, polyoxyethylene styrol
ether, polyoxyethylene lanolin derivatives, ethylene oxide
derivatives of alkylphenol formalin condensates, polyoxyethylene
polyoxypropylene block polymers, fatty acid esters of
polyoxyethylene polyoxypropylene alkylether polyoxyethylene
compounds, ethylene glycol fatty acid esters of polyethylene oxide
condensation type, fatty acid monoglycerides, fatty acid esters of
polyglycerol, fatty acid esters of propylene glycol, cane sugar
fatty acid esters, fatty acid alkanol amides, polyoxyethylene fatty
acid amides and polyoxyethylene alkylamine oxides. Even among the
various surfactant mentioned above, those with ionic groups are
preferably used. Besides, among these surfactants, it is preferable
to use anionic or nonionic surfactans for the carbon having an
anionic hydrophilic group on the surface, or cationic or nonionic
surfactants for the carbon having a cationic hydrophilic group.
[0087] (Dodecylbenzenesulfonate)
[0088] Meanwhile, a change in ink characteristics accompanying the
pH change of ink can be made astonishingly slow, surprisingly in
this embodiment, when a dodecylbenzenesulfonate (sodium salt,
potassium salt, ammonium salt or the like) as a surfactant is added
to an ink comprising a self dispersible carbon black charged
anionically by introducing a hydrophilic group such as --COO(M2),
--SO.sub.3(M2), --PO.sub.3H(M2) and --PO.sub.3(M2).sub.2, where M2
in the formulae represents a hydrogen atom, alkali metal, ammonium
or an organo-ammonium and R represents a C.sub.1-C.sub.12alkyl
group, a substituted or unsubstituted phenyl group or a substituted
or unsubstituted naphthyl group, directly or indirectly on the
surface and further a salt concurrently. Namely, the line (a) in
FIG. 10 shows an outline of a pH change depending on a viscosity
change of an ink comprising an anionically charged self dispersible
carbon black and a salt in coexistence, included in the first
embodiment. Like this, ink according to the first embodiment tends
to change somewhat greatly in ink characteristics with a pH change.
However, addition of a dedocylbenzene-sulfonate to such ink can
mitigate a change of ink characteristics for a pH change extremely
as shown in the line (b) of FIG. 10. Here, the content of a
dodecylbenzenesulfonate in ink is preferably 0.02 to 0.2% by weight
relative to the whole weight of ink.
[0089] (Third embodiment)
[0090] Next, as a third embodiment of the present invention, ink
prepared from ink according to the first or second embodiment by
setting the pH to 9 to 12, in particular to 9 to 11, can be
mentioned. As mentioned above, the inventors have been aware of
that the pH dependence of ink characteristics is rather great and a
pH value tends to lower with a longer period of preservation for
the ink according to the first embodiment of the present invention.
If the pH of ink lies within the above range, however, a change
with time in characteristics of ink is on an almost negligible
order.
[0091] Unless otherwise adjusted, the pH of the ink described in
the first or second embodiment is normally on the order of 7 to 8.
Such the pH value of ink can be adjusted to a desired one, e.g. by
using an hydroxide, such as specifically potassium hydroxide,
aqueous ammonia solution or lithium hydroxide. Meanwhile, when ink
was preserved for a long period of time, the pH changes by the
order of 1, specifically lowers in some cases depending on a
composition and preserving conditions. In order to retain such a pH
value in ink after the long-term preservation within the above
range, it is preferable to adjust the initial pH to a somewhat
higher value within the range of from 9 to 12 beforehand.
[0092] Here, the ink with the pH of ink according to the second
embodiment, i.e. ink comprising a dodecylbenzenesulfonate
as-stabilizer, adjusted to within the above range can be
appropriately used in particular as ink for ink-jet recording. This
is because, due to the effect of mitigating the pH dependence of
ink characteristics for ink obtained by the content of a
dodecylbenzenesulfonate, variations in ink characteristics reduces
more and more within the above pH range. Besides, since the amount
of a dodecylbenzenesulfonate is added only to extent sufficient for
suppressing the variation in ink characteristics in the above pH
range, the effect of minimizing the addition of a
dodecylbenzenesulfonate is also displayed.
[0093] (Fourth embodiment)
[0094] As ink according to a fourth embodiment of the present
invention, ink with an antioxidant added to ink according to any of
the first to the third embodiments can be mentioned. Such addition
of an antioxidant can improve the preserving stability of ink still
more.
[0095] Examples of antioxidants may include sodium sulfite, sodium
hydrogensulfite, ascorbic acid, gallic acid, 2-naphthol tannic
acid, catechol, o-phenylene diamine and succinic acid and it is
advisable to add one or more compounds selected from these to
ink.
[0096] Although the action of these compounds added to ink is
obscure, the progress of oxidation with time, for example, in
water-soluble solvent such as, e.g. ethylene glycol is considered
to affect the disperse state of pigments and the above compounds
can effectively prevent the oxidation of the above solvents, so
that the long-period preservability of ink is presumed to be
stabilized.
[0097] Here, if the addition of an antioxidant is set to 0.02 to
10% by weight, in particular 0.1 to 2% by weight relative to the
whole weight of ink, promotion the preserving stability is
achievable with hardly any change in ink characteristics.
[0098] (Fifth embodiment)
[0099] As ink according to a fifth embodiment of the present
invention, ink with a water-soluble polymer compound added to ink
according to any one of the first to the fourth embodiments can be
mentioned. Such addition of a water-soluble polymer compound can
improve the frictional resistance of an image after the recording
of the image by depositing this ink to the surface of a recording
medium.
[0100] (Water-soluble polymer compounds)
[0101] Examples of water-soluble polymer compounds include
styrene-acrylic acid copolymers, styrene-acrylic acid-alkyl
acrylate terpolymers, styrene-methacrylic acid copolymers,
styrene-maleic acid copolymers, styrene-maleic acid-alkyl acrylate
terpolymers, styrene-methacrylic acid-alkyl acrylate terpolymers,
styrene-maleic acid half ester copolymers, vinyl
naphthalene-acrylic acid copolymers, alginic acid, polyacrylic
acids or their salts and their derivatives.
[0102] And, a weight average molecular weight of a water-soluble
polymer compound used here is set preferably to the order of 1,000
to 5,000, for example, and the content of a water-soluble polymer
compound is set preferably to 0.02 to 2% by weight, in particular
to 0.05 to 1% by weight to the whole weight of ink. Namely, if the
molecular weight and the content in ink are set to such respective
ranges, a variation of ink viscosity or ink ejecting
characteristics with the addition of a water-soluble polymer
compound can be minimized to substantially negligible extent while
the advantages (such as improvement of the frictional resistance of
a recorded image) of the added water-soluble polymer compound is
secured.
[0103] (Ink characteristics: ink-jet ejecting characteristics and
permeability through recording media)
[0104] Ink according to each of the embodiments mentioned above can
be used as ink for writing tools and ink for ink-jet recording. As
ink-jet recording methods, there are a recording method in which a
mechanical energy is applied to ink to eject liquid droplets and a
recording method in which a thermal energy is applied to ink to
eject liquid droplets under action of bubbles of an ink, for both
of which ink according to the present invention is especially
suitable. When using the ink according to each of the embodiments
for ink-jet recording, it is preferable for the ink to have a
characteristic capable of being ejected from an ink-jet head. From
the viewpoint of ejection property from an ink-jet head, a
viscosity and a surface tension, for example, are set preferably to
1 to 15 cP and 25 dyn/cm or stronger, in particular to 1 to 5 cP
and 25 to 50 dyn/cm, respectively, as characteristics of the
liquid.
[0105] Besides, as an index indicating a permeability of ink to a
recording medium, there is a Ka value determined by the Bristow
method. Namely, the permeating amount V (ml/m.sup.2=.mu.m) of ink
to a recording medium after the lapse of a predetermined time t
from the an ink droplet is ejected is expressed in terms of the
Bristow formula:
V=Vr+Ka (t-tw).sup.1/2,
[0106] supposing that the permeability of ink is expressed by an
ink amount V per m.sup.2, tw is a contact time and Vr is an amount
of ink absorbed.
[0107] Here, directly after the depositing of an ink droplet to the
surface of a recording medium, almost all ink is absorbed in the
uneven portion (rough portion on a surface of recording medium) of
the recording medium surface and almost none permeates into the
recording medium interior. The duration time is a contact time (tw)
and the amount of ink absorbed in the uneven portion of a recording
medium during the contact time is Vr. Then, when the contact time
elapsed after the depositing of ink, the amount of ink permeating
through a recording medium increases in proportion to 1/2 power of
the elapsed time exceeding the contact time, i.e., (t-tw). A Ka
value is a proportional coefficient of this increment and
represents a value corresponding to the permeating speed. And, the
Ka value is measurable by using a dynamic permeability testing
device (such as Dynamic Permeability Testing Device S, trade name,
a product of TOYO Seiki Mfg., Ltd.) for a liquid by the Bristow
method. Furthermore, in ink according to each of the embodiment
mentioned above, setting this Ka value to not more than 1.5 is
preferable for further promoting the quality of a recorded image,
more preferably a Ka value of from 0.2 to 1.5. With ink comprising
a self dispersible carbon black and a salt, for example, according
to the first embodiment, the solid-liquid separation is accelerated
on a recording medium, greatly contributing to the promotion of
image quality as mentioned above. For a Ka value of not more than
1.5, since the solid-liquid separation takes place at an earlier
stage of the permeating process of ink through a recording medium,
a high quality image with very few feathering seems capable of
being formed on various recording media under cooperation with the
addition of a salt to ink. Incidentally, the Ka value by the
Bristow method in the present invention is measured on plain paper
(such as PB paper available from Canon Inc. and serving for copiers
or page printers (laser beam printers) using the electronic
photography process or for ink-jet printers using the ink-jet
recording process and PPC paper serving for copiers using the
electronic photography process) employed as a recording medium.
Besides, as measuring environments, general office environments
such as temperature of from 20 to 25.degree. C. and humidity of
from 40 to 60% are assumed.
[0108] And, as composition of aqueous medium allowing ink according
to each of the embodiments mentioned above to carry the above
characteristics, those comprising glycerol, trimethylol propane,
thiodiglycol, ethylene glycol, diethylene glycol, isopropyl alcohol
and acetylene alcohols are preferable. Incidentally, as one example
of acetylene alcohol, the one expressed in terms of the chemical
formula mentioned below can be mentioned: 3
[0109] where n+m is 10.
[0110] In particular, for a Ka value set to not more than 1.5 as
mentioned above, the desired ink can be attained by appropriately
adding a surfactant such as acetylenol, a permeative solvent or the
like at a predetermined amount.
[0111] Furthermore, in addition to the above components,
surfactants, defoaming agents, antiseptics, antimolds, etc. can be
added to make ink having desired property values if necessary and
further commercially available water-soluble dyes may be added.
[0112] (Ink-jet recording technology)
[0113] An ink-jet recording technology in which the above-described
inks can be suitably used will hereinafter be described.
[0114] Examples of a head construction, which is a main component
of an ink-jet recording apparatus of a system that thermal energy
is used to eject an ink will be shown in FIGS. 1 and 2.
[0115] FIG. 1 is a schematic cross-sectional view of a head 13
taken along an ink flow path, and FIG. 2 is a cross-sectional view
taken along line 2-2 in FIG. 1. In FIGS. 1 and 2, the head 13 is
formed by bonding a glass, ceramic, silicon or plastic plate or the
like having a flow path (nozzle) 14, through which an ink is
passed, to a heating element substrate 15. The heating element
substrate 15 is composed of a protective film 16 made of silicon
oxide, silicone nitride, silicon carbide or the like, aluminum
electrodes 17-1 and 17-2 made of aluminum, aluminum-copper alloy or
the like, a heating resistor layer 18 made of a high-melting point
material such as HfB.sub.2, TaN, TaAl and the like, a heat
accumulating layer 19 made of thermally oxidized silicon, aluminum
oxide or the like, and a substrate 20 made of silicone, aluminum,
alumina nitride or the like having a good heat radiating
property.
[0116] Now, upon application of electric signals to the electrodes
17-1 and 17-2 in a form of a pulse, the heating element substrate
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
(for example, paper) 25 in the form of minute droplets 24 and
applied to a recording medium 25.
[0117] 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.
[0118] (Ink-jet recording apparatus)
[0119] FIG. 4 illustrates an example of an ink-jet recording
apparatus in which such a head as described above 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 65 operates, and in this embodiment, is held in such a form
that it protrudes into the course through which the recording head
65 is moved.
[0120] 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 65 is moved, and comes into contact with the face of
ejection openings to cap it. Reference numeral 63 denotes an
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 65 is moved. The
above-described blade 61, cap 62 and absorbing member 63 constitute
an ejection-recovery portion 64, where the blade 61 and absorbing
member 63 remove water, dust and/or the like from the face of the
ink-ejecting openings.
[0121] 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) at its part 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 paper feeding part from which the recording
paper is inserted, and paper feed rollers driven by a motor (not
illustrated), respectively.
[0122] With such a construction, the recording paper 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.
[0123] 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.
[0124] 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.
[0125] 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 65 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.
[0126] (Ink cartridge)
[0127] FIG. 5 illustrates an exemplary ink cartridge 45 in which an
ink to be fed to a 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 absorbing member for
receiving a waste ink. It is preferred that the ink container
portion be formed of a polyolefin, in particular, polyethylene, at
its surface with which the ink comes into contact.
[0128] (Recording unit)
[0129] The ink-jet recording apparatus used in the present
invention are 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.
[0130] 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 is preferably used as a material for the ink-absorbing
member.
[0131] Alternatively, the ink container portion may be so
constituted that it is an ink bag mounted with a spring and the
like, without using 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 can
be used in place of the recording head 65 shown in FIG. 4, and is
detachably installed on the carriage 66.
[0132] Next, as a second embodiment of an ink-jet recording
apparatus utilizing mechanical energy, there may be exemplified an
On-Demand ink-jet recording head, which is provided with a
nozzle-formed substrate having a plurality of nozzles, a
pressure-generating element composed of a piezo-electric material
and a electric conductive material positioned opposing to the
nozzles and an ink which fills the surrounding of the
pressure-generating element, and which can eject ink-droplets from
the nozzles, by deforming the pressure-generating element upon a
voltage-application. An example of a construction of the head which
constitutes a recording apparatus is shown in FIG. 7.
[0133] The head is constituted with the ink flow path 80
communicated with an ink chamber (not shown), an orifice plate 81
for ejecting an ink droplet of a desired volume, a vibration plate
82 which serves to apply directly a pressure to the ink, a piezo
electric element 83 which deforms by an electric signal and is
connected with the vibration plate and a substrate 84 for
supporting and fixing the vibration plate and the like.
[0134] In FIG. 7, the ink flow path 80 is made of a photosensitive
resin and the like, the orifice plate 81 is made of a metal such as
stainless steel, nickel and the like and an ejection opening 85 is
formed thereon by punching the plate by means of electrocasting or
press processing, the vibration plate 82 is formed from a metal
film such as stainless steel, nickel, titanium and the like, or
from a elastic resin film or the like and the piezo electric
element 83 is made of a ferroelectric material such as barium
titanate, PZT and the like. The recording head thus constituted
operates so as to provide a voltage to the piezo electric element
83 in a form of pulse, to generate a strain stress, to deform the
vibration plate connected with the piezo electric element 83 by the
stress, and to press the ink in the ink flow path 80
perpendicularly to eject ink droplets (not shown) from the orifice
85 of the orifice plate 81, thereby conducing recording. Such the
recording head can be used upon mounted in the same recording
apparatus as shown in FIG. 4.
[0135] (Ink set)
[0136] Meanwhile, ink according to each of the first to the fifth
embodiments mentioned constitutes a black ink. This ink can provide
an ink set appropriately used for the formation of a color image by
its combination with at least one color ink selected from the group
consisting of a color ink comprising a coloring material for
yellow, a color ink comprising a coloring material for magenta, a
color ink comprising a coloring material for cyan, a color ink
comprising a coloring material for red, a color ink comprising a
coloring material for blue and a color ink comprising a coloring
material for green. And, when such an ink set is used to make a
record in which the black image portion and the color image portion
are adjacent with each other, the occurrence of bleeding can be
very effectively eliminated. Incidentally, the reason for such an
ink set to very effectively eliminate the occurrence of bleeding is
obscure, but is attributable to the effect of a rapid progress of
solid-liquid separation and a subsequent solidification of the
colorant after the depositing of the black ink to a recording
medium by making black ink coexistent with a self dispersible
carbon black and a salt, thus leading to a difficulty in exudation
of black ink to the side of color ink at the boundary of color
image portion.
[0137] (Color ink)
[0138] Here, as coloring materials of color ink usable for the
above ink set, publicly-known dyes or pigments can be employed.
Examples of usable dyes include acid dyes and direct dyes. As
anionic dyes, for example, most of the existing or newly
synthesized ones are usable only if moderate in color tone and
density. Besides, any mixture of these is also usable. Specific
examples of anionic dyes will be mentioned below.
[0139] (Yellow coloring materials)
[0140] C.I. Direct Yellow 8, 11, 12, 27, 28, 33, 39, 44, 50, 58,
85, 86, 87, 88, 89, 98, 100 and 110;
[0141] C.I. Acid Yellow 1, 3, 7, 11, 17, 23, 25, 29, 36, 38, 40,
42, 44, 76, 98 and 99;
[0142] C.I. Reactive Yellow 2, 3, 17, 25, 37 and 42; and
[0143] C.I. Food Yellow 3
[0144] (Red coloring materials)
[0145] C.I. Direct Red 2, 4, 9, 11, 20, 23, 24, 31, 39, 46, 62, 75,
79, 80, 83, 89, 95, 197, 201, 218, 220, 224, 225, 226, 227, 228 and
229;
[0146] C.I. Acid Red 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 42, 51,
52, 80, 83, 87, 89, 92, 106, 114, 115, 133, 134, 145, 158, 198,
249, 265 and 289;
[0147] C.I. Reactive Red 7, 12, 13, 15, 17, 20, 23, 24, 31, 42, 45,
46 and 59; and
[0148] C.I. Food Red 87, 92 and 94.
[0149] (Blue coloring materials)
[0150] C.I. Direct Blue 1, 15, 22, 25, 41, 76, 77, 80, 86, 90, 98,
106, 108, 120, 158, 163, 168, 199 and 226;
[0151] C.I. Acid Blue 1, 7, 9, 15, 22, 23, 25, 29, 40, 43, 59, 62,
74, 78, 80, 90, 100, 102, 104, 117, 127, 138, 158 and 161; and
[0152] C.I. Reactive Blue 4, 5, 7, 13, 14, 15, 18, 19, 21, 26, 27,
29, 32, 38, 40, 44 and 100.
[0153] (Black coloring materials)
[0154] C.I. Acid Black 2, 4, 8, 51, 52, 110, 115 and 156; and
[0155] C.I. Food Black 1 and 2.
[0156] (Solvent)
[0157] As a solvent or dispersion medium of ink comprising coloring
materials for color ink as mentioned above, water or a solvent
mixture of water and a water-soluble organic solvent, for example,
is mentioned. And, as a water-soluble organic solvent, the same
ones as described in the first embodiment are mentioned. Besides,
in case of depositing the color ink to a recording medium by the
ink-jet method (such as bubble jet method), ink is preferably
prepared so as to have a desired viscosity and surface tension,
leading to excellency in ink-jet ejecting characteristics.
[0158] (Contents of coloring materials)
[0159] Here, the content of coloring materials in each color ink
needs to be appropriately selected only so as to be excellent in
ink ejecting characteristics and to have a desired color tone and
density, for example, in use for ink-jet recording, but lies
preferably in the range of, e.g. from 3 to 50% by weight relative
to the whole weight of ink as a standard. On the other hand, the
water content in ink lies preferably in the range of from 50 to 95%
by weight relative to the whole weight of ink.
[0160] (Permeability of color ink)
[0161] With respect to color ink as mentioned above, setting the Ka
value of ink, for example, to 5 or more, enabling a high quality
color image to be formed on a recording medium, is preferable.
Namely, even in case of recording images of at least two colors
selected, e.g. from yellow, magenta and cyan, adjacently, ink
having such a Ka value can eliminate the bleeding between the
adjacent images on account of its high permeability through a
recording medium. Even if these colors of ink are printed in
overlapping to form an image of secondary color, the bleeding
between the adjacent images of different colors can be eliminated
because individual colors of ink are highly permeable. To the
preparation of color ink in such a value of Ka, a former
publicly-known method, such as, e.g. addition of a surfactant or
addition of a permeative solvent such as glycol ether, is
applicable and needless to say, the added amount needs only to be
chosen appropriately.
[0162] (Recording apparatus and recording method using the ink
set)
[0163] In use of the above ink set for recording a color image, a
recording apparatus with four recording heads lined up on a
carriage, e.g as shown in FIG. 3, can be used. FIG. 9 shows one
embodiment thereof, in which recording units 91, 92, 93 and 94 are
provided respectively for ejecting yellow, magenta, cyan and black
ink, for example. The recording units are disposed on the carriage
in the above recording apparatus and jet individual colors of ink
in response to recording signals. Besides, FIG. 9 shows an example
of using four recording units, but the present invention is not
limited to this and an embodiment comprising a single recording
head 95 with the flow path so divided as to allow the four
respective colors of ink, supplied from ink cartridges 86 to 89
each containing the four colors of ink on one recording head, to be
individually ejected for recording, for example, as shown in FIG. 8
is also mentioned.
[0164] Hereinafter, referring to Examples and Comparative Examples,
the present invention will be described still more specifically but
is not limited by the Examples mentioned later without departing
from its essential points. Incidentally, in the following
description, a designation of "part" and "%" is based on the weight
unless otherwise specified.
[0165] Experimental Example I--(1) (Evaluation of the ink according
to the first embodiment):
[0166] First of all, Pigment dispersions 1 to 4 were prepared.
[0167] Pigment dispersion 1:
[0168] After fully mixing 10 g of carbon black having a surface
area of 230 m.sup.2/g and DBP oil absorption of 70 ml/100 g and
3.41 g of p-amino-benzoic acid with 72 g of water, 1.62 g of nitric
acid was added drop by drop to the mixture with stirring at
70.degree. C. Here, several seconds later, a solution of 1.07 g of
sodium nitrite dissolved in 5 g of water was add with further
stirring for 1 hour. The obtained slurry was filtered through
filter paper, TOYO Filter Paper No. 2 (trade name, a product of
Advantis Co.), and the pigment particles filtered out were fully
washed with water and dried on a 90.degree. C. oven. Further water
was added to this pigment to prepare a 10% by weight aqueous
dispersion of pigment. By the above method, the group expressed in
terms of the chemical formula: 4
[0169] was introduced to the surface of carbon black.
[0170] Pigment dispersion 2:
[0171] At 5.degree. C., 1.58 g of anthranilic acid was added to a
solution of 5 g of concentrated hydrochloric acid dissolved in 5.3
g of water. To this, while keeping a temperature of not higher than
10.degree. C. with stirring in an ice bath, a solution of 1.78 g of
sodium nitrite dissolved in 8.7 g of water was added at 5.degree.
C. To this, after further stirring for 15 minutes, 20 g of carbon
black having a surface area of 320 m.sup.2/g and DBP oil absorption
of 120 ml/100 g was added in a state of mixture and stirred further
for 15 minutes. The obtained slurry was filtered through filter
paper, TOYO Filter Paper No. 2 (trade name, a product of Advantis
Co.), and the pigment particles filtered out were fully washed with
water and dried on a 110.degree. C. oven. Further water was added
to this pigment to prepare a 10% by weight aqueous dispersion of
pigment. By the above method, the group expressed in the term of
chemical formula: 5
[0172] was introduced to the surface of carbon black.
[0173] Pigment dispersion 3:
[0174] To the Pigment dispersion 2 prepared above, sulfuric acid
was added so as to bring the pH to the order of 4.5 and the
carboxyl group bonded to the surface of carbon black was made into
H type. Thereafter, the mixture was centrifuged at 5,000 rpm for 5
minutes, the precipitate was taken out and again dispersed into
pure water. By repeating this centrifugal treatment three times,
carbon was washed with water. Furthermore, the pH of this disperse
solution was adjusted to the order of 8 by the addition of
NH.sub.4OH. By these treatments, the counter ion of a carboxyl
group bonded to the carbon surface was converted from Na.sup.+ into
NH.sub.4.sup.+. And, the Pigment dispersion containing such a self
dispersible carbon black was made to Pigment dispersion 3.
[0175] Pigment dispersion 4:
[0176] Carbon black with --COONa groups introduced to the surface
by the following method was prepared.
[0177] After 300 g of acidic carbon black MA-77 (pH 3.0) (trade
name, a product of Mitsubishi Chemical Industries Ltd.) fully mixed
with 1,000 ml of water, 450 g of sodium hypochlorite solution
(effective chlorine concentration 12%) was added drop by drop to
this mixture, and stirred at 100 to 105.degree. C. for 10 hour. The
obtained slurry was filtered through filter paper, TOYO Filter
Paper No. 2 (trade name, a product of Advantis Co.), and the
pigment particles filtered out were fully washed with water. Wet
cake of this pigment was again dispersed into 3,000 ml of water and
desalted with a reverse osmosis membrane to an electric
conductivity of 0.2 .mu.s. Furthermore, this Pigment dispersion (pH
8 to 10) was concentrated to a pigment concentration of 10% by
weight to obtain carbon black on the surface of which a --COONa
group was introduced.
[0178] Next, Black Inks 1 to 4 were prepared by employing
aftermentioned Pigment dispersions 1 to 4, as follows.
[0179] (Black Ink 1)
[0180] After the following components were mixed and dissolved
fully with stirring, the solution was filtered through a micro
filer having a pore size of 3 .mu.m (available from Fuji Photo Film
Co., Ltd) under pressure to prepare Black Ink 1.
1 Pigment dispersion 1: 30 parts potassium sulfate: 1 part
trimethylol propane: 6 parts glycerol: 6 parts diethylene glycol: 6
parts acetylene glycol ethyleneoxide adduct 0.2 part (ACETYLENOL
EH, trade name, a product of KAWAKEN Fine Chemical, Ltd.): water:
50.8 parts
[0181] (Black Ink 2)
[0182] Using the following components, Black Ink 2 was prepared in
the same manner as in the Black Ink 1.
2 Pigment dispersion 2: 30 parts potassium chlorite: 0.5 part
trimethylol propane: 6 parts acetylene glycol ethyleneoxide adduct
0.15 part (ACETYLENOL EH, trade name, a product of KAWAKEN Fine
Chemical, Ltd.): glycerol: 5 parts ethylene glycol: 5 parts water:
53.35 parts
[0183] (Black Ink 3)
[0184] Using the following components, Black Ink 3 was prepared in
the same manner as in the Black Ink 1.
3 Pigment dispersion 3: 30 parts ammonium benzoate: 1 part
trimethylol propane: 6 parts acetylene glycol ethyleneoxide adduct
0.15 part (ACETYLENOL EH, trade name, a product of KAWAKEN Fine
Chemical, Ltd.): glycerol: 5 parts diethylene glycol: 5 parts
water: 52.85 parts
[0185] (Black Ink 4)
[0186] After the following components were mixed and dissolved
fully with stirring, the solution was filtered through a micro
filer having a pore size of 3.0 .mu.m, (available from Fuji Photo
Film Co., Ltd.) under pressure to prepare Black Ink 4.
4 Pigment dispersion 4: 30 parts acetylene glycol ethyleneoxide
adduct 0.15 part (ACETYLENOL EH, trade name, a product of KAWAKEN
Fine Chemical, Ltd.): glycerol: 5 parts diethylene glycol: 5 parts
trimethylol propane: 6 parts water: 53.85 parts
[0187] The main characteristics of the Black Inks 1 to 4 are shown
in Table 1.
5 TABLE 1 Atomic group interposed between Self dispersible the self
dispersible carbon black carbon black surface Hydrophilic and a
hydrophilic group of the Counter group surface ion Salt in ink
Black Ink 1 phenylene group --COO.sup.- Na.sup.+ K.sub.2SO.sub.4
Black Ink 2 phenylene group --COO.sup.- Na.sup.+ KCl Black Ink 3
phenylene group --COO.sup.- NH.sub.4.sup.+ C.sub.6H.sub.5--
COONH.sub.4 Black Ink 4 none --COO.sup.- Na.sup.+ none
[0188] By using an ink-jet recording apparatus, BJC-4000 (trade
name, a product of Canon Inc.) equipped with an on-demand recording
multi-head for applying thermal energy to ink in response to a
recording signal for ejecting the ink, the following evaluations
were made on each of the above Black Inks 1 to 4. The results are
shown in Table 2.
[0189] 1) Character quality grade
[0190] In each of the above inks, the above ink-jet recording
apparatus is used to execute character printing on 5 types of plain
paper A, B, C, D and E for copy, different in the permeability of
ink and the resistance to bleeding of characters observed at that
time was evaluated on the basis of the following criteria:
[0191] A: PPC paper NSK available from Canon Inc.
[0192] B: PPC paper NDK available from Canon Inc.
[0193] C: PPC paper 4024 available from Xerox Corp.
[0194] D: PPC Prover bond paper available from Fox River.
[0195] E: PPC paper for CANON Inc. available from Neusiedler
Co.
[0196] .smallcircle.: Hardly any bleeding is observed on any of
five types of paper.
[0197] .DELTA.: Bleeding is observed on some types of paper.
[0198] x: Bleeding takes place on all five types of paper.
[0199] 2) Optical density of print
[0200] In each of the above ink, the above ink-jet recording
apparatus is used to execute character printing on 5 types of plain
paper A, B, C, D and E for copy and the optical density of print
observed at that time was measured using a Macbeth optical density
of print measuring device and estimated on the basis of the
following criteria:
[0201] .smallcircle.: Difference of not more than 0.1 in optical
density of print of plain paper A, B, C, D and E for copy between
maximum and minimum
[0202] x: Difference of 0.1 or greater in optical density of print
of plain paper A, B, C, D and E for copy between maximum and
minimum.
[0203] 3) Water fastness
[0204] In each of the above inks, the above ink-jet recording
apparatus was used to execute character printing on 5 types of
plain paper A, B, C, D and E for copy as in Item 1) above and after
the lapse of a predetermined time, a recording medium printed was
dipped in a water stream to observe the condition of ground dirt
visually and the results were estimated on the basis of the
following criteria:
[0205] .circleincircle.: Ground dirt has become inconspicuous
within an hour after the printing on all types of plain paper for
copy A, B, C, D and E.
[0206] .smallcircle.: Ground dirt has become inconspicuous within
one day after the printing on all types of plain paper for copy A,
B, C, D and E.
[0207] x: Ground dirt remains conspicuous on some type of plain
paper even after the lapse of one day or longer from the
printing.
[0208] 4) Intermittent ejecting property
[0209] The above ink-jet recording apparatus was used to print a
longitudinal line on plain paper for copy A, then print a
longitudinal line again 30 seconds later and a difference between
the two lines obtained was evaluated on the basis of the following
criteria without performing pre-ejection or suction.
[0210] .circleincircle.: No difference is detectable even through
observing with a loupe (a magnifying glass) between both lines.
[0211] .smallcircle.: No difference is detectable visually between
both lines.
[0212] .DELTA.: A difference is detectable visually between both
lines, but presents no problem in practical use.
6 TABLE 2 Character Optical density Water Intermittent quality
grade of print fastness ejecting Black Ink 1 .smallcircle.
.smallcircle. .smallcircle. .DELTA. Black Ink 2 .smallcircle.
.smallcircle. .smallcircle. .smallcircle. Black Ink 3 .smallcircle.
.smallcircle. .circleincircle. .circleincircle. Black Ink 4 .DELTA.
x .smallcircle. .DELTA.
[0213] As understood from the results of Table 2, the ink according
to the first embodiment of the present invention is high in
character quality and optical density of print for the recording,
e.g. by the ink-jet recording method and these results hardly
depend on types of paper.
[0214] Besides, Black Ink 3 with the counter ion of a hydrophilic
group of self dispersible carbon black made to ammonium salt and
moreover ammonium benzoate employed as the salt in the ink
exhibited an excellent effect especially in water fastness.
[0215] Experimental Example I--(2) (Evaluation of the ink set using
ink according to the first embodiment):
[0216] (Black Ink 1)
[0217] Black Ink 1 prepared in the same manner as in the Black Ink
1 of Experimental Example I--(1) was made ready.
[0218] (Black Ink 2)
[0219] Black Ink 2 prepared in the same manner as in the Black Ink
2 of Experimental Example I--(1) was made ready.
[0220] (Black Ink 3)
[0221] Black Ink 3 prepared in the same manner as in the Black Ink
3 of Experimental Example I--(1) was made ready.
[0222] (Black Ink 5)
[0223] In the same manner as in the Black Ink 1, Black Ink 5 was
prepared using the following components:
7 Pigment dispersion 3 prepared in Experimental 30 parts Example I
- (1): acetylene glycol ethylene oxide adduct 0.15 part (ACETYLENOL
EH, trade name, a product of KAWAKEN Fine Chemical, Ltd.):
trimethylol propane: 6 parts glycerol: 5 parts diethylene glycol: 5
parts water: 53.85 parts
[0224] (Black Ink 6)
[0225] Preparation of Pigment dispersion 5:
[0226] By the following method, the Pigment dispersion 5 was
prepared.
[0227] First of all, the following components were mixed and heated
to 70.degree. C. in a water bath to dissolve the resin part
completely.
8 styrene-acrylic acid-butylacrylate terpolymer 3 parts (acid
value: 60; weight average molecular weight: 13,000):
1,3-bis-(.beta.-hydroxyethyl) urea: 0.5 part ion exchange water:
72.5 parts diethylene glycol: 5 parts
[0228] Next, to the above mixture, 14 parts of carbon black, Color
Black S170 (trade name, a product of Degussa) and 5 parts of
isopropyl alcohol were added with premixing for 30 minutes and
thereafter subjected to a disperse treatment under the following
conditions:
[0229] Dispersing machine: Sand grinder (available from Igarashi
Kikai Co.)
[0230] Pulverizing media: 1 mm diameter zirconium beads
[0231] Fill ratio of pulverizing media: 50% (by volume)
[0232] Pulverizing time: 3 hour
[0233] After the disperse treatment, a centrifugal treatment
(12,000 rpm; for 20 minutes) was further made to remove rough
particles, thereby obtaining Pigment dispersion 5.
[0234] Next, using the following components, Black Ink 6 was
prepared in the same manner as in the Black Ink 1 mentioned
above.
9 Pigment dispersion 5: 30 parts acetylene glycol ethylene oxide
adduct 0.15 part (ACETYLENOL EH, trade name, a product of KAWAKEN
Fine Chemical, Ltd.): ethyl alcohol: 6 parts 2-methyl pyrrolidone:
6 parts water: 57.85 parts
[0235] (Yellow Ink 1)
[0236] After the following components were mixed and dissolved
fully with stirring, the solution was filtered through a micro
filer having a pore size of 3.0 .mu.m, (available from Fuji Photo
Film Co., Ltd.) under pressure to prepare Yellow Ink 1.
10 acetylene glycol ethylene oxide adduct 1 part (ACETYLENOL EH,
trade name, a product of KAWAKEN Fine Chemical, Ltd.): diethylene
glycol: 10 parts glycerol: 5 parts C.I. Direct Yellow 86: 3 parts
water: 81 parts
[0237] (Magenta Ink 1)
[0238] Using the following components, Magenta Ink 1 was prepared
in the same manner as in the Yellow Ink 1 mentioned above.
11 acetylene glycol ethylene oxide adduct 1 part (ACETYLENOL EH,
trade name, a product of KAWAKEN Fine Chemical, Ltd.):
thiodiglycol: 20 parts C.I. Acid Red 35: 3 parts water: 76
parts
[0239] (Cyan Ink 1)
[0240] Using the following components, Cyan Ink 1 was prepared in
the same manner as in the Yellow Ink 1 mentioned above.
12 acetylene glycol ethylene oxide adduct 1 part (ACETYLENOL EH,
trade name, a product of KAWAKEN Fine Chemical, Ltd.): diethylene
glycol: 35 parts C.I. Acid Blue 9: 3 parts water: 61 parts
[0241] Example 1
[0242] An ink set was prepared by the following combination of the
inks prepared above.
[0243] Black Ink 1
[0244] Yellow Ink 1
[0245] Magenta Ink 1
[0246] Cyan Ink 1
[0247] Example 2
[0248] An ink set was prepared by the following combination of the
inks prepared above.
[0249] Black Ink 2
[0250] Yellow Ink 1
[0251] Magenta Ink 1
[0252] Cyan Ink 1
[0253] Example 3
[0254] An ink set was prepared by the following combination of the
inks prepared above.
[0255] Black Ink 3
[0256] Yellow Ink 1
[0257] Magenta Ink 1
[0258] Cyan Ink 1
[0259] Comparative Example 1
[0260] An ink set was prepared by the following combination of the
inks prepared above.
[0261] Black Ink 5
[0262] Yellow Ink 1
[0263] Magenta Ink 1
[0264] Cyan Ink 1
[0265] Comparative Example 2
[0266] An ink set was prepared by the following combination of the
inks prepared above.
[0267] Black Ink 6
[0268] Yellow Ink 1
[0269] Magenta Ink 1
[0270] Cyan Ink 1
[0271] Table 3 shows the main compositions of individual types of
Black Ink constituting the ink sets of Examples 1 to 3 and
Comparative Examples 1 and 2.
13 TABLE 3 Atomic group interposed between the self Self
dispersible dispersible carbon black carbon black Hydro- surface
and a philic hydrophilic group of Counter Disper- group the surface
ion Salt in ink sant Example 1 phenylene --COO.sup.- Na.sup.+
K.sub.2SO.sub.4 None (Black Ink group 1) Example 2 phenylene
--COO.sup.- Na.sup.+ KCl None (Black Ink group 2) Example 3
phenylene --COO.sup.- NH.sub.4.sup.+ C.sub.6H.sub.5COONH.sub.4 None
(Black Ink group 3) Com- phenylene --COO.sup.- Na.sup.+ None None
parative group Example 1 (Black Ink 5) Com- None None None None
Present parative Example 2 (Black Ink 6)
[0272] The ink sets of Examples 1 to 3 and Comparative Examples 1
and 2 were used to make a record on the same 5 types of plain paper
for copy A to E as mentioned above with the aid of an ink-jet
recording apparatus BJC-4000 (trade name, a product of Canon Inc.)
equipped with an on-demand recording multi-head for giving thermal
energy to ink in response to a recording signal for ejecting ink
and the following evaluations were performed as follows. The
results are shown in Table 4.
[0273] 1) Resistance to bleeding
[0274] Solid printing was conducted on 5.times.5 meshed square
portions (each portion's size: 2 cm.times.2 cm) in a 10 cm square,
alternatively with black and color inks, and resistance to bleeding
at the boundary between the black printing portion and the color
printing portion was evaluated on the basis of the following
criteria:
[0275] .smallcircle.: A boundary line between two colors is sharp
and neither bleeding nor color mixture is observed.
[0276] .DELTA.: The presence of a boundary line between two colors
is clear, but a certain degree of bleeding or color mixture at the
boundary is observed on part of paper types.
[0277] x: No boundary line between two colors is discernible.
14 TABLE 4 Resistance to bleeding Example 1 .smallcircle. Example 2
.smallcircle. Example 3 .smallcircle. Comparative Example 1 x
Comparative Example 2 x
[0278] As evident from the above results, a color image free from
or scant of bleeding can be recorded with any ink set using ink
according to the first embodiment.
[0279] Pigment dispersion 6:
[0280] After fully mixing 10 g of carbon black having a surface
area of 230 m.sup.2/g and DBP oil absorption of 70 ml/100 g and
3.06 g of 3-amino-N-ethyl pyridinium bromide with 72 g of water,
1.62 g of nitric acid was added drop by drop to the mixture with
stirring at 70.degree. C. Here, several seconds later, a solution
of 1.07 g of sodium nitrite dissolved in 5 g of water was add with
further stirring for 1 hour. The obtained slurry was filtered
through filter paper TOYO Filter Paper No. 2 (trade name, a product
of Advantis Co.), and the pigment particles filtered out were fully
washed with water and dried on a 110.degree. C. oven. Further water
was added to this pigment to prepare a 10% by weight aqueous
dispersion of pigment. By the above method, the group expressed in
terms of the chemical formula: 6
[0281] was introduced to the surface of carbon black.
[0282] (Black Ink 7)
[0283] After the Pigment dispersion 6 mentioned above and following
components were mixed and dissolved fully with stirring, the liquid
mixture was filtered through a micro filer having a pore size of
3.0 .mu.m (available from Fuji Photo Film Co., Ltd.) under pressure
to prepare Black Ink 7.
15 Pigment dispersion 6: 30 parts ammonium sulfate: 2 parts
trimethylol propane: 6 parts sodium tetradecylsulfonate: 0.1 parts
glycerol: 6 parts thiodiglycol: 6 parts water: 49.9 parts
[0284] The main features of the Black Ink 7 obtained thus are shown
below.
16 Atomic group interposed between the self Self dispersible carbon
black dispersible carbon black Hydrophilic surface and a
hydrophilic group of the Counter group surface ion Salt in ink
Black Ink 7 none 7 NO.sub.3.sup.- (NH.sub.4).sub.2SO.sub.4
[0285] The character quality grade, optical density of print, and
water fastness were evaluated for Black Ink 7 above according to
the method and criteria identical to those employed for Black Inks
1 to 4 above, and all the evaluated items were judged as
".smallcircle.".
[0286] Experimental Example II--(1) (Evaluation of the ink
according to the second embodiment):
[0287] (Black Ink 8)
[0288] After the following components were mixed and dissolved with
fully stirring, the solution was filtered through a micro filer
having a pore size of 3 .mu.m (available from Fuji Photo Film Co.,
Ltd.) under pressure to prepare Black Ink 8.
17 Pigment dispersion 1: 30 parts potassium sulfate: 1 part sodium
dodecylbenzenesulfonate: 0.1 part trimethylol propane: 6 parts
glycerol: 6 parts diethylene glycol: 6 parts acetylene glycol
ethyleneoxide adduct 0.2 part (ACETYLENOL EH, trade name, a product
of KAWAKEN Fine Chemical, Ltd.): water: 50.7 parts
[0289] (Black Ink 9)
[0290] Using the following components, Black Ink 9 was prepared in
the same manner as in the Black Ink 8 mentioned above.
18 Pigment dispersion 2: 30 parts potassium chloride: 0.5 part
sodium dodecylbenzenesulfonate: 0.15 part trimethylol propane: 6
parts acetylene glycol ethyleneoxide adduct 0.15 part (ACETYLENOL
EH, trade name, a product of KAWAKEN Fine Chemical, Ltd.):
glycerol: 5 parts ethylene glycol: 5 parts water: 53.2 parts
[0291] (Black Ink 10)
[0292] Using the following components, Black Ink 10 was prepared in
the same manner as in the Black Ink 8 mentioned above.
19 Pigment dispersion 2: 30 parts ammonium sulfate: 2 parts sodium
dodecylbenzenesulfonate: 0.1 part trimethylol propane: 6 parts
sodium tetradecylsulfonate: 0.1 parts glycerol: 6 parts
thiodiglycol: 6 parts water: 49.8 parts
[0293] (Black Ink 11)
[0294] Using the following components, Black Ink 11 was prepared in
the same manner as in the Black Ink 8 mentioned above.
20 Pigment dispersion 3: 30 parts ammonium benzoate: 1 part sodium
dodecylbenzenesulfonate: 0.15 part trimethylol propane: 6 parts
acetylene glycol ethyleneoxide adduct 0.15 part (ACETYLENOL EH,
trade name, a product of KAWAKEN Fine Chemical, Ltd.): glycerol: 5
parts ethylene glycol: 5 parts water: 52.7 parts
[0295] The main features of the Black Inks 8 to 11 mentioned above
are shown in Table 5.
21 TABLE 5 Atomic group interposed between the self Self
dispersible dispersible carbon black carbon black Hydro- surface
and a philic hydrophilic group of Counter group the surface ion
Salt Stability Black phenylene --COO.sup.- Na.sup.+ K.sub.2SO.sub.4
sodium Ink 8 group dodecyl- benzene- sulfonate Black phenylene
--COO.sup.- Na.sup.+ KCl sodium Ink 9 group dodecyl- benzene-
sulfonate Black phenylene --COO.sup.- Na.sup.+
(NH.sub.4).sub.2SO.sub.4 sodium Ink 10 group dodecyl- benzene-
sulfonate Black phenylene --COO.sup.- NH.sub.4.sup.+
C.sub.6H.sub.5COONH.sub.4 sodium Ink 11 group dodecyl- benzene-
sulfonate
[0296] An evaluation was made of the preserving stability of each
of the Black Inks 8 to 11 mentioned above. Namely, in four 100 ml
capacity glass receptacles (available from Shot Co.), 100 ml of the
respective Black Inks 8 to 11 mentioned above were put into
individual receptacles and left standing at 60.degree. C. for one
month to observe the presence of a change in ink viscosity between
before and after the standing. The results are shown in Table 6.
Incidentally, the criteria are as follows:
[0297] .smallcircle.: Hardly any viscosity change in ink is
recognizable between before and after the standing.
[0298] x: A viscosity change in ink is recognizable between before
and after the standing.
22 TABLE 6 Reserving stability Black Ink 8 .smallcircle. Black Ink
9 .smallcircle. Black Ink 10 .smallcircle. Black Ink 11
.smallcircle.
[0299] Experimental Example II--(2) (Evaluation of the ink
according to the second embodiment):
[0300] (Black Ink 8)
[0301] Black Ink 8 prepared in the same manner as in the Black Ink
8 of Experimental Example II--(1) was made ready.
[0302] (Black Ink 9)
[0303] Black Ink 9 prepared in the same manner as in the Black Ink
9 of Experimental Example II--(1) was made ready.
[0304] (Black Ink 10)
[0305] Black Ink 10 prepared in the same manner as in the Black Ink
10 of Experimental Example II--(1) was made ready.
[0306] (Black Ink 11)
[0307] Black Ink 11 prepared in the same manner as in the Black Ink
11 of Experimental Example II--(1) was made ready.
[0308] (Yellow Ink 1)
[0309] Yellow Ink 1 prepared in the same manner as in the Yellow
Ink 1 of Experimental Example I--(2) was made ready.
[0310] (Magenta Ink 1)
[0311] Magenta Ink 1 prepared in the same manner as in the Magenta
Ink 1 of Experimental Example I--(2) was made ready.
[0312] (Cyan Ink 1)
[0313] Cyan Ink 1 prepared in the same manner as in the Cyan Ink 1
of Experimental Example I--(2) was made ready.
[0314] Example 4
[0315] An ink set was prepared by the following combination of the
color inks prepared above.
[0316] Black Ink 8
[0317] Yellow Ink 1
[0318] Magenta Ink 1
[0319] Cyan Ink 1
[0320] Example 5
[0321] Black Ink 9
[0322] Yellow Ink 1
[0323] Magenta Ink 1
[0324] Cyan Ink 1
[0325] Example 6
[0326] Black Ink 10
[0327] Yellow Ink 1
[0328] Magenta Ink 1
[0329] Cyan Ink 1
[0330] Example 7
[0331] Black Ink 11
[0332] Yellow Ink 1
[0333] Magenta Ink 1
[0334] Cyan Ink 1
[0335] On the ink sets of Examples 4 to 7, an evaluation was made
with respect to resistance to bleeding in the same manner as in
Experimental Example I--(2). The results are shown in Table 7.
23 TABLE 7 Resistance to Bleeding Example 4 .smallcircle. Example 5
.smallcircle. Example 6 .smallcircle. Example 7 .smallcircle.
[0336] Experimental Example III--(1) (Evaluation of the ink
according to the third embodiment):
[0337] (Black Ink 12)
[0338] After the following components were mixed and dissolved
fully with stirring, the solution was adjusted to a pH of 10.5 by
adding potassium hydroxide and thereafter filtered through a micro
filer having a pore size of 3 .mu.m (available from Fuji Photo Film
Co., Ltd.) under pressure to prepare Black Ink 12.
24 Pigment dispersion 1 prepared in Experimental 30 parts Example I
- (1): potassium sulfate: 1 part trimethylol propane: 6 parts
glycerol: 6 parts diethylene glycol: 6 parts acetylene glycol
ethyleneoxide adduct 0.2 part (ACETYLENOL EH, trade name, a product
of KAWAKEN Fine Chemical, Ltd.): water: 50.8 parts
[0339] (Black Ink 13)
[0340] Using the following components, Black Ink 13 was prepared in
the same manner as in the Black Ink 12 mentioned above.
Incidentally, the pH was adjusted to 11 by using an aqueous
ammonia.
25 Pigment dispersion 2 prepared in Experimental 30 parts Example I
- (1): potassium chloride: 0.5 part trimethylol propane: 6 parts
acetylene glycol ethyleneoxide adduct 0.15 part (ACETYLENOL EH,
trade name, a product of KAWAKEN Fine Chemical, Ltd.): glycerol: 5
parts ethylene glycol: 5 parts water: 53.35 parts
[0341] (Black Ink 14)
[0342] Using the following components, Black Ink 14 was prepared in
the same manner as in the Black Ink 12 mentioned above.
Incidentally, the pH was adjusted to 11 by using a lithium
hydroxide.
26 Pigment dispersion 2 prepared in Experimental 30 parts Example I
- (1): ammonium sulfate: 2 parts trimethylol propane: 6 parts
sodium tetradecylsulfonate: 0.1 part glycerol: 6 parts
thiodiglycol: 6 parts water: 49.9 parts
[0343] (Black Ink 15)
[0344] Using the following components, Black Ink 15 was prepared in
the same manner as in the Black Ink 12 mentioned above.
Incidentally, the pH was adjusted to 11 by using an aqueous
ammonia.
27 Pigment dispersion 3 prepared in Experimental 30 parts Example I
- (1): ammonium benzoate: 1 part trimethylol propane: 6 parts
acetylene glycol ethyleneoxide adduct 0.15 part (ACETYLENOL EH,
trade name, a product of KAWAKEN Fine Chemical, Ltd.): glycerol: 5
parts ethylene glycol: 5 parts water: 52.85 parts
[0345] The main features of the Black Inks 12 to 15 obtained thus
are shown in Table 8.
28 TABLE 8 Atomic group interposed be- tween the self dispersible
Self dispersible carbon black carbon black surface and Hydrophilic
a hydrophilic group of the Counter group surface ion Salt in ink pH
Black phenylene --COO.sup.- Na.sup.+ K.sub.2SO.sub.4 10.5 Ink 12
group Black phenylene --COO.sup.- Na.sup.+ KCl 11 Ink 13 group
Black phenylene --COO.sup.- Na.sup.+ (NH.sub.4).sub.2SO.sub.4 11
Ink 14 group Black phenylene --COO.sup.- NH.sub.4.sup.+
C.sub.6H.sub.5COONH.sub.4 11 Ink 15 group
[0346] An evaluation was made for the preserving stability of each
of the Black Inks 12 to 15 mentioned above. Namely, in four 100 ml
capacity glass receptacles (available from Shot Co.), 100 ml of the
respective Black Inks 12 to 15 mentioned above were put into
individual receptacles and left standing to observe the presence of
a change in ink viscosity between before and after the standing.
The results are shown in Table 9. Incidentally, the criteria are as
follows:
[0347] .smallcircle.: Hardly any viscosity change in ink is
recognizable between before and after the standing.
[0348] x: A viscosity change in ink is recognizable between before
and after the standing.
29 TABLE 9 Reserving stability Black Ink 12 .smallcircle. Black Ink
13 .smallcircle. Black Ink 14 .smallcircle. Black Ink 15
.smallcircle.
[0349] Experimental Example III--(2):
[0350] (Black Ink 12)
[0351] Black Ink 12 prepared in the same manner as in the Black Ink
12 of Experimental Example III--(1) was made ready.
[0352] (Black Ink 13)
[0353] Black Ink 13 prepared in the same manner as in the Black Ink
13 of Experimental Example III--(1) was made ready.
[0354] (Black Ink 14)
[0355] Black Ink 14 prepared in the same manner as in the Black Ink
14 of Experimental Example III--(1) was made ready.
[0356] (Black Ink 15)
[0357] Black Ink 15 prepared in the same manner as in the Black Ink
15 of Experimental Example III--(1) was made ready.
[0358] (Black Ink 16)
[0359] After the following components were mixed and dissolved
fully with stirring, the solution was adjusted to a pH of 11 by
using potassium hydroxide and thereafter filtered through a micro
filer having a pore size of 3 .mu.m (available from Fuji Photo Film
Co., Ltd.) under pressure to prepare Black Ink 16.
30 Pigment dispersion 5 prepared in Experimental 30 parts Example I
- (2): acetylene glycol ethyleneoxide adduct 0.15 part (ACETYLENOL
EH, trade name, a product of KAWAKEN Fine Chemical, Ltd.): ethyl
alcohol: 6 parts 2-methylpyrrolidone: 6 parts water: 57.85
parts
[0360] (Yellow Ink 1)
[0361] Yellow Ink 1 prepared in the same manner as in the Yellow
Ink 1 of Experimental Example I--(2) was made ready.
[0362] (Magenta Ink 1)
[0363] Magenta Ink 1 prepared in the same manner as in the Magenta
Ink 1 of Experimental Example I--(2) was made ready.
[0364] (Cyan Ink 1)
[0365] Cyan Ink 1 prepared in the same manner as in the Cyan Ink 1
of Experimental Example I--(2) was made ready.
[0366] Example 8
[0367] An ink set was prepared by the following combination of the
inks made ready above.
[0368] Black Ink 12
[0369] Yellow Ink 1
[0370] Magenta Ink 1
[0371] Cyan Ink 1
[0372] Example 9
[0373] An ink set is prepared by the following combination of the
inks made ready above.
[0374] Black Ink 13
[0375] Yellow Ink 1
[0376] Magenta Ink 1
[0377] Cyan Ink 1
[0378] Example 10
[0379] An ink set is prepared by the following combination of the
inks made ready above.
[0380] Black Ink 14
[0381] Yellow Ink 1
[0382] Magenta Ink 1
[0383] Cyan Ink 1
[0384] Example 11
[0385] An ink set is prepared by the following combination of the
inks made ready above.
[0386] Black Ink 15
[0387] Yellow Ink 1
[0388] Magenta Ink 1
[0389] Cyan Ink 1
[0390] Comparative Example 3
[0391] Black Ink 16
[0392] Yellow Ink 1
[0393] Magenta Ink 1
[0394] Cyan Ink 1
[0395] Table 10 shows the main features of the Black Ink
constituting the ink sets of Examples 8 to 11 and Comparative
Example 3.
31 TABLE 10 Atomic group interposed between the self dispersible
Self dispersible carbon black carbon black surface and Hydrophilic
a hydrophilic group of the Counter group surface ion Salt in ink pH
Example phenylene --COO.sup.- Na.sup.+ K.sub.2SO.sup.4 10.5 8
(Black group Ink 12) Example phenylene --COO.sup.- Na.sup.+ KCl 11
9 (Black group Ink 13) Example phenylene --COO.sup.- Na.sup.+
(NH.sub.4).sub.2SO.sub.4 11 10 (Black group Ink 14) Example
phenylene --COO.sup.- NH.sub.4.sup.+ C.sub.6H.sub.5COONH.sub.4 11
11 (Black group Ink 15) Compara- None None None 11 tive example 3
(Black Ink 16)
[0396] On the ink sets of Examples 9 to 12 and Comparative Example
3, an evaluation was made for resistance to bleeding in the same
manner as in Experimental Example I--(2). The results are shown in
Table 11.
32 TABLE 11 Resistance to bleeding Example 8 .smallcircle. Example
9 .smallcircle. Example 10 .smallcircle. Example 11 .smallcircle.
Comparative example 3 x
[0397] Experimental Example IV--(1) (Evaluation of the ink
according to the fourth embodiment):
[0398] (Black Ink 17)
[0399] Using the following components, Black Ink 17 was prepared in
the same manner as in the Black Ink prepared above.
33 Pigment dispersion 1 of Experimental Example I-(1) 30 parts
potassium sulfate 1 part sodium sulfite 0.3 part trimethylol
propane 6 parts glycerol 6 parts diethylene glycol 6 parts
acetylene glycol ethylene oxide adduct 0.2 part (ACETYLENOL EH,
trade name, a product of KAWAKEN Fine Chemical, Ltd.) water 50.5
parts
[0400] (Black Ink 18)
[0401] Using the following components, Black Ink 18 was prepared in
the same manner as in the Black Ink prepared above.
34 Pigment dispersion 2 of Experimental Example I-(1) 30 parts
potassium chloride 0.5 part sodium ascorbate 0.15 part trimethylol
propane 6 parts glycerol 5 parts ethylene glycol 5 parts acetylene
glycol ethylene oxide adduct 0.15 part (ACETYLENOL EH, trade name,
a product of KAWAKEN Fine Chemical, Ltd.) water 53.2 parts
[0402] (Black Ink 19)
[0403] Using the following components, Black Ink 19 was prepared in
the same manner as in the Black Ink prepared above.
35 Pigment dispersion 2 of Experimental Example I-(1) 30 parts
ammonium sulfate 2 parts sodium sulfite 0.1 part trimethylol
propane 6 parts sodium tetradecylsulfonate 0.1 parts glycerol 6
parts thiodiglycol 6 parts water 49.8 parts
[0404] (Black Ink 20)
[0405] Using the following components, Black Ink 20 was prepared in
the same manner as in the Black Ink prepared above.
36 Pigment dispersion 3 of Experimental Example I-(1) 30 parts
ammonium benzoate 1 part sodium ascorbate 0.15 part trimethylol
propane 6 parts glycerol 5 parts ethylene glycol 5 parts acetylene
glycol ethylene oxide adduct 0.15 part (ACETYLENOL EH, trade name,
a product of KAWAKEN Fine Chemical, Ltd.) water 52.7 parts
[0406] The main features of the respective Black Inks 17 to 20
obtained thus are shown in Table 12.
37TABLE 12 Atomic group interposed between the Self dispersible
self depersible carbon black carbon black Hydrophilic surface and a
group of Counter Anti- hydrophilic group the surface ion Salt
oxidant Black phenylene group -COO- Na.sup.+ K.sub.2SO.sub.4 sodium
Ink sulfite 17 Black phenylene group -COO- Na.sup.+ KCl sodium Ink
ascorbate 18 Black phenylene group -COO- Na.sup.+ (NH.sub.4).sub.2-
sodium Ink SO.sub.4 sulfite 19 Black phenylene group -COO-
NH.sub.4.sup.+ C.sub.6H.sub.5- sodium Ink COONH.sub.4 ascorbate
20
[0407] An estimate was made on the preserving stability of each of
the Black Inks 17 to 20 mentioned above as the same way as in the
Experimental Example II--(1). The results are shown in Table
13.
38 TABLE 13 Reserving stability Black Ink 17 .smallcircle. Black
Ink 18 .smallcircle. Black Ink 19 .smallcircle. Black Ink 20
.smallcircle.
[0408] Experimental Example IV--(2) (Evaluation of ink sets using
the ink according to the fourth embodiment):
[0409] (Black Ink 17)
[0410] Black Ink 17 prepared in the same manner as in the Black Ink
17 of Experimental Example IV--(1) was made ready.
[0411] (Black Ink 18)
[0412] Black Ink 18 prepared in the same manner as in the Black Ink
18 of Experimental Example IV--(1) was made ready.
[0413] (Black Ink 19)
[0414] Black Ink 19 prepared in the same manner as in the Black Ink
19 of Experimental Example IV--(1) was made ready.
[0415] (Black Ink 20)
[0416] Black Ink 20 prepared in the same manner as in the Black Ink
20 of Experimental Example IV--(1) was made ready.
[0417] (Yellow Ink 1)
[0418] Yellow Ink 1 prepared in the same manner as in the Yellow
Ink 1 of Experimental Example I--(2) was made ready.
[0419] (Magenta Ink 1)
[0420] Magenta Ink 1 prepared in the same manner as in the Magenta
Ink 1 of Experimental Example I--(2) was made ready.
[0421] (Cyan Ink 1)
[0422] Cyan Ink 1 prepared in the same manner as in the Cyan Ink 1
of Experimental Example I--(2) was made ready.
[0423] Example 12
[0424] An ink set is prepared by the following combination of the
inks made ready above.
[0425] Black Ink 17
[0426] Yellow Ink 1
[0427] Magenta Ink 1
[0428] Cyan Ink 1
[0429] Example 13
[0430] An ink set is prepared by the following combination of the
inks made ready above.
[0431] Black Ink 18
[0432] Yellow Ink 1
[0433] Magenta Ink 1
[0434] Cyan Ink 1
[0435] Example 14
[0436] An ink set is prepared by the following combination of the
inks made ready above.
[0437] Black Ink 19
[0438] Yellow Ink 1
[0439] Magenta Ink 1
[0440] Cyan Ink 1
[0441] Example 15
[0442] An ink set is prepared by the following combination of the
inks made ready above.
[0443] Black Ink 20
[0444] Yellow Ink 1
[0445] Magenta Ink 1
[0446] Cyan Ink 1
[0447] On the ink sets of Examples 12 to 15, an evaluation was made
on resistance to bleeding in the same manner as in Experimental
Example I--(2). The results are shown in Table 14.
39 TABLE 14 Resistance to bleeding Example 12 .smallcircle. Example
13 .smallcircle. Example 14 .smallcircle. Example 15
.smallcircle.
[0448] Experimental Example V--(1) (Evaluation of the ink according
to the fifth embodiment):
[0449] (Black Ink 21)
[0450] Using the following components, Black Ink 21 was prepared in
the same manner as in the Black Ink prepared above.
40 Pigment dispersion 1 of Experimental Example I-(1) 30 parts
potassium sulfate 1 part trimethylol propane 6 parts glycerol 6
parts diethylene glycol 6 parts acetylene glycol ethylene oxide
adduct 0.2 part (ACETYLENOL EH, trade name, a product of KAWAKEN
Fine Chemical, Ltd.) sodium alginate 0.1 part water 50.7 parts
[0451] (Black Ink 22)
[0452] Using the following components, Black Ink 22 was prepared in
the same manner as in the Black Ink prepared above.
41 Pigment dispersion 2 of Experimental Example I-(1) 30 parts
potassium chloride 0.5 part trimethylol propane 6 parts glycerol 5
parts ethylene glycol 5 parts acetylene glycol ethylene oxide
adduct 0.15 part (ACETYLENOL EH, trade name, a product of KAWAKEN
Fine Chemical, Ltd.) sodium polyacrylate 0.1 part water 53.25
parts
[0453] (Black Ink 23)
[0454] Using the following components, Black Ink 23 was prepared in
the same manner as in the Black Ink prepared above.
42 Pigment dispersion 3 of Experimental 30 parts Example I - (1):
ammonium benzoate: 1 part trimethylol propane: 6 parts glycerol: 5
parts ethylene glycol: 5 parts acetylene glycol ethylene oxide
adduct 0.15 part (ACETYLENOL EH, trade name, a product of KAWAKEN
Fine Chemical, Ltd.): sodium polyacrylate: 0.1 part water: 52.75
parts
[0455] (Black Ink 24)
[0456] Using the following components, Black Ink 24 was prepared in
the same manner as in the Black Ink prepared above.
43 Pigment dispersion 6 of Experimental 30 parts Example I - (2):
ammonium sulfate: 2 parts trimethylol propane: 6 parts sodium
alginate: 0.1 part glycerol: 6 parts thiodiglycol: 6 parts water:
49.9 parts
[0457] The main features of the Black Inks 21 to 24 obtained thus
are shown in Table 15.
44 TABLE 15 Atomic group interposed between the self dispersible
Water- carbon black Self dispersible carbon black soluble surface
and a Hydrophilic group Counter polymer hydrophilic group of the
surface ion Salt compound Black Ink phenylene group --COO.sup.-
Na.sup.+ K.sub.2SO.sub.4 sodium 21 alginate Black Ink phenylene
group --COO.sup.- Na.sup.+ KCl sodium 22 polyacry- late Black Ink
phenylene group --COO.sup.- NH.sub.4.sup.+
C.sub.6H.sub.5COONH.sub.4 sodium 23 polyacry- late Black Ink 24
None 8 NO.sub.3.sup.- (NH.sub.4).sub.2SO.sub.4 sodium alginate
[0458] Each of the Black Inks 21 to 24 mentioned above was applied
to an ink-jet recording apparatus BJC-4000 (trade name, a product
of Canon Inc.) equipped with an on-demand recording multi-head for
applying thermal energy to ink in response to a recording signal
for ejecting ink and the following evaluations were performed as
follows. The results are shown in Table 16.
[0459] 1) Character quality Grade
[0460] Each of the above inks is charged to the above ink-jet
recording apparatus to execute character printing on 5 types of
plain paper for copy A, B, C, D and E mentioned above and the
resistance to bleeding of characters observed at that time was
evaluated on the basis of the following criteria:
[0461] .smallcircle.: Hardly any bleeding is observed on any type
of paper.
[0462] .DELTA.: Bleeding is observed on some types of paper.
[0463] x: Bleeding takes place on all five types of paper.
[0464] 2) Optical Density of Print
[0465] Each of the above inks is charged to the above ink-jet
recording apparatus to execute character printing on 5 types of
plain paper for copy A, B, C, D and E and the optical density of
print observed at that time was measured using a optical density of
print measuring device available from Macbeth Co. and evaluated on
the basis of the following criteria:
[0466] .smallcircle.: Difference of not more than 0.1 in optical
density of print of plain paper for copy A, B, C, D and E between
maximum and minimum.
[0467] x: Difference of 0.1 or greater in optical density of print
of plain paper for copy A, B, C, D and E between maximum and
minimum.
[0468] 3) Scratch Resistance
[0469] Each of the above inks was charged to the above ink-jet
recording apparatus to execute character printing on 5 types of
plain paper for copy A, B, C, D and E and, after left standing for
one-day, a scratch test was made on the printed paper by using a
weight of 40 g/cm.sup.2 load to evaluate the scratch resistance on
the basis of the criteria mentioned below:
[0470] .smallcircle.: No stain is noticeable on any type of
paper.
[0471] .DELTA.: Stains are noticeable on some types of paper.
[0472] x: Stains are noticeable on all types of paper.
[0473] 4) Water fastness
[0474] Each of the above inks was charged to the above ink-jet
recording apparatus to execute character printing on 5 types of
plain paper for copy A, B, C, D and E as in Item 1) and after the
lapse of a predetermined time, a recording medium printed was
dipped in a water stream to observe the condition of ground dirt
visually and the results were evaluated on the basis of the
following criteria:
[0475] .circleincircle.: Ground dirt has become inconspicuous
within an hour after the printing on all types of plain paper for
copy A, B, C, D and E.
[0476] .smallcircle.: Ground dirt has become inconspicuous within
one day after the printing on all types of plain paper for copy A,
B, C, D and E.
[0477] x: Ground dirt remains conspicuous on some type of plain
paper even after the lapse of one day or longer from the
printing.
45 TABLE 16 Character Quality Optical Density Scratch Water Grade
of Print Resistance fastness Black Ink 21 .smallcircle.
.smallcircle. .smallcircle. .smallcircle. Black Ink 22
.smallcircle. .smallcircle. .smallcircle. .smallcircle. Black Ink
23 .smallcircle. .smallcircle. .smallcircle. .circleincircle. Black
Ink 24 .smallcircle. .smallcircle. .smallcircle. .smallcircle.
[0478] Experimental Example V--(2) (Evaluation of ink sets using
the ink according to the fifth embodiment):
[0479] (Black Ink 21)
[0480] Black Ink 21 prepared in the same manner as in the Black Ink
21 of Experimental Example V--(1) was made ready.
[0481] (Black Ink 22)
[0482] Black Ink 22 prepared in the same manner as in the Black Ink
22 of Experimental Example V--(1) was made ready.
[0483] (Black Ink 23)
[0484] Black Ink 23 prepared in the same manner as in the Black Ink
18 of Experimental Example V--(1) was made ready.
[0485] (Black Ink 24)
[0486] Black Ink 24 was prepared in the same manner as in the Black
Ink 23 of Experimental Example V--(1) was made ready.
[0487] (Black Ink 25)
[0488] Using the following components in the same manner as in the
Black Ink prepared above Black Ink 25 was prepared:
46 Pigment dispersion 2 of Experimental 30 parts Example I- (1):
ammonium sulfate: 2 parts trimethylol propane: 6 parts sodium
alginate: 0.1 part glycerol: 6 parts thiodiglycol: 6 parts water:
49.9 parts
[0489] (Yellow Ink 1)
[0490] Yellow Ink prepared in the same manner as in the Yellow Ink
1 of Experimental Example I--(2) was made ready.
[0491] (Magenta Ink 1)
[0492] Magenta Ink prepared in the same manner as in the Magenta
Ink 1 of Experimental Example I--(2) was made ready.
[0493] (Cyan Ink 1)
[0494] Cyan Ink prepared in the same manner as in the Cyan Ink 1 of
Experimental Example I--(2) was made ready.
[0495] Example 16
[0496] An ink set was prepared by the following combination of
various types of color ink made ready above.
[0497] Black Ink 21
[0498] Yellow Ink 1
[0499] Magenta Ink 1
[0500] Cyan Ink 1
[0501] Example 17
[0502] An ink set was prepared by the following combination of the
inks made ready above.
[0503] Black Ink 22
[0504] Yellow Ink 1
[0505] Magenta Ink 1
[0506] Cyan Ink 1
[0507] Example 18
[0508] An ink set was prepared by the following combination of the
inks made ready above.
[0509] Black Ink 23
[0510] Yellow Ink 1
[0511] Magenta Ink 1
[0512] Cyan Ink 1
[0513] Example 19
[0514] An ink set was prepared by the following combination of the
inks made ready above.
[0515] Black Ink 25
[0516] Yellow Ink 1
[0517] Magenta Ink 1
[0518] Cyan Ink 1
[0519] Comparative Example 4
[0520] An ink set similar to that employed for Comparative Example
2 in Experimental Example I--(2) was made ready above.
[0521] Table 17 shows the main features of the black ink types used
in the ink sets of Examples 16 to 19 and Comparative Example 4.
47 TABLE 17 Atomic group interposed between Self dispersible the
self dispersible carbon black Water- carbon black surface
Hydrophilic soluble and a hydrophilic group of the Counter polymer
group surface ion Salt compound Example 16 phenylene group
--COO.sup.- Na.sup.+ K.sub.2SO.sub.4 sodium (Black Ink alginate 21)
Example 17 phenylene group --COO.sup.- Na.sup.+ KCl sodium (Black
Ink polyacry- 22) late Example 18 phenylene group --COO.sup.-
NH.sub.4.sup.+ C.sub.6H.sub.5COONH.sub.4 sodium (Black Ink
polyacry- 23) late Example 19 phenylene group --COO.sup.- Na.sup.+
(NH.sub.4).sub.2SO.sub.4 sodium (Black Ink alginate 25) Comparative
None None None None example 4 (Black Ink 6)
[0522] On the ink sets of Examples 17 to 20 and Comparative Example
4, an evaluation was made on resistance to bleeding in the same
manner as in Experimental Example I--(2), while an evaluation was
made on scratch resistance in the same manner as in Experimental
Example V--(1). The results are shown in Table 18.
48 TABLE 18 Resistance to Scratch bleeding resistance Example 16
.smallcircle. .smallcircle. Example 17 .smallcircle. .smallcircle.
Example 18 .smallcircle. .smallcircle. Example 19 .smallcircle.
.smallcircle. Comparative example 4 x .DELTA.
[0523] As described above, according to individual embodiments of
the present invention, for example, the following advantages can be
obtained.
[0524] (1) Ink capable of mitigating the influence of recording
media exerted upon the image quality grade and stably giving a high
grade image can be obtained.
[0525] (2) Ink capable of minimizing the pH dependence of ink
quality and stably keeping the properties of ink is obtained.
[0526] (3) Ink hardly changeable in quality e.g. in ejecting
property of ink even for a long period of preservation, is
obtained.
[0527] (4) Ink excellent in the scratch resistance of printed
matter and that almost independently of recording medium types can
be obtained.
[0528] (5) An ink set capable of effectively inhibiting the
bleeding can be obtained.
[0529] (6) An imaging apparatus and an imaging method capable of
mitigating the influence of recording media exerted upon the image
quality grade and stably forming a high grade image and further an
ink cartridge and a recording unit used therein can be
obtained.
* * * * *