U.S. patent application number 13/633019 was filed with the patent office on 2013-04-11 for sulfonated dye salts exhibiting reduced kogation.
This patent application is currently assigned to Silverbrook Research Pty Ltd. The applicant listed for this patent is Silverbrook Research Pty Ltd. Invention is credited to Graciel Gonzaga, Sutharsiny Indusegaram, Damon Donald Ridley, Kia Silverbrook, Simone Charlotte Vonwiller.
Application Number | 20130090481 13/633019 |
Document ID | / |
Family ID | 41464607 |
Filed Date | 2013-04-11 |
United States Patent
Application |
20130090481 |
Kind Code |
A1 |
Vonwiller; Simone Charlotte ;
et al. |
April 11, 2013 |
Sulfonated dye salts exhibiting reduced kogation
Abstract
A sulfonated dye salt of formula (II): ##STR00001## wherein M is
Ga(A.sup.1); A.sup.1 is an axial ligand selected from the group
consisting of: --OH and halogen; and Z.sub.1.sup.+, Z.sub.2.sup.+,
Z.sub.3.sup.+ and Z.sub.4.sup.+ are independently selected from the
group consisting of: H and an ammonium cation. At least one of
Z.sub.1.sup.+, Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ is
the ammonium cation. The ammonium cation is protonated
2,2-bis(hydroxymethyl)-2,2',2''-nitrilotriethanol. Such salts
exhibit reduced kogation in thermal bubble-forming inkjet
printheads.
Inventors: |
Vonwiller; Simone Charlotte;
(Balmain, AU) ; Indusegaram; Sutharsiny; (Balmain,
AU) ; Gonzaga; Graciel; (Balmain, AU) ;
Ridley; Damon Donald; (Balmain, AU) ; Silverbrook;
Kia; (Balmain, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Silverbrook Research Pty Ltd; |
Balmain |
|
AU |
|
|
Assignee: |
Silverbrook Research Pty
Ltd
Balmain
AU
|
Family ID: |
41464607 |
Appl. No.: |
13/633019 |
Filed: |
October 1, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13225481 |
Sep 5, 2011 |
8282722 |
|
|
13633019 |
|
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|
12466337 |
May 14, 2009 |
8029611 |
|
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13225481 |
|
|
|
|
61078319 |
Jul 3, 2008 |
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Current U.S.
Class: |
548/402 |
Current CPC
Class: |
C09D 11/328 20130101;
C09B 47/065 20130101; Y10T 428/24802 20150115; B41J 2002/14475
20130101; C09B 69/04 20130101; B41J 2/1404 20130101; C09B 47/04
20130101; B41J 2202/03 20130101; C09B 47/24 20130101; C09B 47/0678
20130101 |
Class at
Publication: |
548/402 |
International
Class: |
C09B 47/04 20060101
C09B047/04 |
Claims
1. A sulfonated dye salt of formula (II): ##STR00011## wherein M is
Ga(A.sup.1); A.sup.1 is an axial ligand selected from the group
consisting of: --OH and halogen; and Z.sub.1.sup.+, Z.sub.2.sup.+,
Z.sub.3.sup.+ and Z.sub.4.sup.+ are independently selected from the
group consisting of: H and an ammonium cation, wherein at least one
of Z.sub.1.sup.+, Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ is
said ammonium cation and said ammonium cation is protonated
2,2-bis(hydroxymethyl)-2,2',2''-nitrilotriethanol.
2. The sulfonated dye salt of claim 1, wherein at least three of
Z.sub.1.sup.+, Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ are
said ammonium cation.
3. The sulfonated dye salt of claim 1, wherein each of
Z.sub.1.sup.+, Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ is
said ammonium cation.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation Application of
U.S. application Ser. No. 13/225,481 filed Sep. 5, 2011, which is a
Continuation Application of U.S. application Ser. No. 12/466,337
filed May 14, 2009, now issued U.S. Pat. No. 8,029,611, which is
herein incorporated by reference.
FIELD OF THE INVENTION
[0002] The present application relates to sulfonated dyes suitable
for printing inks, such as inkjet inks. It has been developed
primarily for reducing kogation of such dyes in an inkjet
printhead.
CROSS-REFERENCES TO RELATED APPLICATIONS
[0003] The following patents or patent applications filed by the
applicant or assignee of the present invention are hereby
incorporated by cross-reference.
TABLE-US-00001 10/815,635 7,357,323 7,605,940 7,506,168 7,905,401
7,457,961 7,457,007 6,902,255 7,204,941 7,278,727 7,423,145
7,122,076 7,148,345 7,658,792 7,837,775 7,416,280 6,755,509
7,156,289 7,721,948 6,720,985 7,295,839 7,593,899 7,068,382
7,094,910 7,062,651 6,644,642 6,549,935 6,987,573 6,727,996
6,760,119 7,064,851 6,290,349 6,428,155 6,785,016 6,831,682
6,741,871 6,965,439 7,663,780 6,870,966 6,474,888 6,724,374
6,788,982 7,263,270 6,788,293 6,737,591 7,369,265 10/778,056
11/193,482 7,055,739 6,830,196 7,182,247 7,082,562 7,918,404
7,108,192 8,028,925 12/025,762 12/015,507 8,219,908 7,469,062
7,359,551 7,444,021 7,308,148 6,957,768 7,170,499 11/856,061
7,762,453 7,821,507
BACKGROUND OF THE INVENTION
[0004] Chemical dyes are important compounds for a range of
applications. For example, inkjet inks typically comprise at least
one colorant in the form of a dye. Many dyes are charged molecules
carrying either a positive or negative charge, which is balanced
with a counterion. The present invention specifically relates to
cationic salts of sulfonated dyes, such as sulfonated
phthalocyanine dyes.
[0005] Sulfonated phthalocyanine dyes are useful in inkjet ink
applications. For example, sulfonated copper phthalocyanines are
well-known cyan dyes. More recently, the present Applicant has
shown that sulfonated gallium naphthlocyanines are useful IR dyes
having minimal visibility and excellent ozonefastness. Accordingly,
sulfonated gallium naphthlocyanines have found utility in the
Applicant's Netpage and Hyperlabel.TM. systems.
[0006] The Netpage and Hyperlabel.TM. systems generally require a
substrate having a position-coding pattern printed thereon. The
coding pattern is preferably printed with an IR-absorbing ink
having minimal visibility, so that it does not interfere with the
visible content of the substrate. A user can interact with the
substrate using an optical sensing device, which reads part of the
coding pattern and generates interaction data. This interaction
data is transmitted to a computer system, which uses the data to
determine what action is being requested by the user. For example,
a user may make handwritten input onto a form, click on a printed
hyperlink, or request information relating to a product item. This
input is interpreted by the computer system with reference to a
page description corresponding to the printed substrate.
[0007] Position-coding patterns for Netpage and Hyperlabel.TM. may
be printed by analogue (e.g. offset) or digital (e.g. inkjet)
printers. If the position-coding pattern is printed using an inkjet
printer, it is important that the printhead has excellent
longevity. Preferably, an IR channel in the printhead, used for
printing the coding pattern, should have at least as good longevity
as other color channels used for printing graphics, text etc.
[0008] Kogation is a term used to describe a phenomenon whereby
residues are deposited over time on a heater element in an inkjet
printhead. Kogation typically occurs from repeated firing of a
heater element and is generally understood to result from
high-temperature deposition of ink component residues. Usually, the
inkjet dye (or pigment) is responsible for kogation on inkjet
heater elements.
[0009] Therefore, an important characteristic of inkjet inks in
thermal inkjet printing is their propensity to kogate on a heater
element. Ideally, an inkjet dye should exhibit minimal kogation,
which consequently improves the lifetime of an inkjet
printhead.
[0010] One approach to minimizing kogation is to add relatively
large amounts of surfactant or other additives to the ink vehicle.
For example, U.S. Pat. No. 6,533,851 describes phosphonate
additives for inkjet inks, which are claimed to reduce kogation.
However, additives of this type generally compromise print quality
by increasing intercolor bleed.
[0011] Another approach to the problem of kogation is to simply
ignore the kogate and `overpower` the heater elements so that water
is superheated through the kogate. This approach is unsatisfactory
in the Applicant's Memjet.RTM. printheads, which use minimal ink
ejection energy for each nozzle so as to achieve high-speed
pagewidth printing. Overpowering each nozzle would inevitably
compromise print speed and/or nozzle density.
[0012] It would therefore be desirable to provide an inkjet dye,
which exhibits reduced kogation. It would be further desirable to
provide an IR-absorbing inkjet dye, which exhibits reduced
kogation.
SUMMARY OF THE INVENTION
[0013] In a first aspect, there is provided a salt of a sulfonated
dye comprising at least one ammonium cation, wherein the or each
ammonium cation comprises at least 3 hydroxyl groups. The ammonium
cation is, of course, the counterion for the anionic sulfonate
moiety in the salt.
[0014] Optionally, the ammonium cation comprises at least 4
hydroxyl groups.
[0015] Optionally, the ammonium cation comprises at least 5
hydroxyl groups.
[0016] Optionally, the ammonium cation is of formula (A):
##STR00002##
wherein: R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9 and R.sup.10
are each independently selected from the group comprising: H and
--CH.sub.2OH.
[0017] Optionally, the ammonium cation is selected from the group
comprising: protonated triethanolamine; and protonated
2,2-bis(hydroxymethyl)-2,2',2''-nitrilotriethanol.
[0018] Optionally, the dye is a sulfonated phthalocyanine dye.
[0019] Optionally, the dye is an IR-absorbing dye.
[0020] Optionally, the salt is of formula (I):
##STR00003##
wherein: Q.sup.1, Q.sup.2, Q.sup.3 and Q.sup.4 are the same or
different and are independently selected from a C.sub.3-20 arylene
group or a C.sub.3-20 heteroarylene group; M is (H.sub.2) or a
metal selected from the group comprising: Si(A.sup.1)(A.sup.2),
Ge(A.sup.1)(A.sup.2), Ga(A.sup.1), Mg, Al(A.sup.1), TiO,
Ti(A.sup.1)(A.sup.2), ZrO, Zr(A.sup.1)(A.sup.2), VO,
V(A.sup.1)(A.sup.2), Mn, Mn(A.sup.1), Fe, Fe(A.sup.1), Co, Ni, Cu,
Zn, Sn, Sn(A.sup.1)(A.sup.2), Pb, Pb(A.sup.1)(A.sup.2), Pd and Pt;
A.sup.1 and A.sup.2 are axial ligands, which may be the same or
different, and are selected from the group comprising: --OH,
halogen, --OR.sup.3, --OC(O)R.sup.4 and
--O(CH.sub.2CH.sub.2O).sub.eR.sup.e wherein e is an integer from 2
to 10 and R.sup.e is H, C.sub.1-8 alkyl or --C(O)C.sub.1-8 alkyl;
R.sup.3 is C.sub.1-20 alkyl, C.sub.5-12 aryl, C.sub.5-20 arylalkyl
or Si(R.sup.x)(R.sup.y)(R.sup.z); R.sup.4 is C.sub.1-20 alkyl,
C.sub.5-12 aryl or C.sub.5-20 arylalkyl; R.sup.x, R.sup.y and
R.sup.z are the same or different and are selected from C.sub.1-12
alkyl, C.sub.5-12 aryl, C.sub.5-12 arylalkyl, C.sub.1-12 alkoxy,
C.sub.5-12 aryloxy or C.sub.5-12 arylalkoxy; and Z.sub.1.sup.+,
Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ are independently
selected from the group comprising: H and an ammonium cation
comprising at least 3 hydroxyl groups, wherein at least one of
Z.sub.1.sup.+, Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ is
said ammonium cation.
[0021] Optionally, the salt is of formula (II):
##STR00004##
wherein M is (H.sub.2) or a metal selected from the group
comprising: Si(A.sup.1)(A.sup.2), Ge(A.sup.1)(A.sup.2),
Ga(A.sup.1), Mg, Al(A.sup.1), TiO, Ti(A.sup.1)(A.sup.2), ZrO,
Zr(A.sup.1)(A.sup.2), VO, V(A.sup.1)(A.sup.2), Mn, Mn(A.sup.1), Fe,
Fe(A.sup.1), Co, Ni, Cu, Zn, Sn, Sn(A.sup.1)(A.sup.2), Pb,
Pb(A.sup.1)(A.sup.2), Pd and Pt; A.sup.1 is an axial ligand
selected from --OH, halogen, --OR.sup.3, --OC(O)R.sup.4 or
--O(CH.sub.2CH.sub.2O).sub.eR.sup.e wherein e is an integer from 2
to 10 and R.sup.e is H, C.sub.1-8 alkyl or C(O)C.sub.1-8 alkyl;
R.sup.3 is selected from C.sub.1-12 alkyl, C.sub.5-12 aryl,
C.sub.5-12 arylalkyl or Si(R.sup.x)(R.sup.y)(R.sup.z); R.sup.4 is
selected from C.sub.1-12 alkyl, C.sub.5-12 aryl or C.sub.5-12
arylalkyl; R.sup.x, R.sup.y and R.sup.z may be the same or
different and are selected from C.sub.1-12 alkyl, C.sub.5-12 aryl,
C.sub.5-12 arylalkyl, C.sub.1-12 alkoxy, C.sub.5-12 aryloxy or
C.sub.5-12 arylalkoxy; and Z.sub.1.sup.+, Z.sub.2.sup.+,
Z.sub.3.sup.+ and Z.sub.4.sup.+ are independently selected from the
group comprising: H and an ammonium cation comprising at least 3
hydroxyl groups, wherein at least one of Z.sub.1.sup.+,
Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ is said ammonium
cation.
[0022] Optionally, at least three of Z.sub.1.sup.+, Z.sub.2.sup.+,
Z.sub.3.sup.+ and Z.sub.4.sup.+ are said ammonium cation.
[0023] In a second aspect, there is provided an inkjet ink
comprising a salt as described above.
[0024] In a third aspect, there is provided a method of reducing
kogation in an inkjet printhead, the method comprising: printing
from the printhead using an inkjet ink as described above.
[0025] Optionally, the printhead comprises a plurality of nozzles,
each nozzle comprising: a nozzle chamber containing said ink; a
heater element for heating said ink; and a nozzle opening for
ejection of ink.
[0026] Optionally, the heater element is comprised of titanium
nitride or a nitride of a titanium alloy.
[0027] Optionally, the heater element is comprised of titanium
aluminium nitride.
[0028] Optionally, the heater element is a cantilever beam
suspended across said nozzle chamber.
[0029] Optionally, the printing includes at least 50 million drop
actuations.
[0030] In a fourth aspect, there is provided an inkjet printhead
comprising a plurality of nozzles, each nozzle comprising: a nozzle
chamber containing an inkjet ink as described above; a heater
element for heating said ink; and a nozzle opening for ejection of
ink.
[0031] Optionally, the heater element is comprised of titanium
aluminium nitride.
[0032] In a fifth aspect, there is provided a substrate having a
salt as described above disposed thereon or therein.
BRIEF DESCRIPTION OF DRAWINGS
[0033] FIG. 1 is a partial perspective view of an array of nozzle
assemblies of a thermal inkjet printhead;
[0034] FIG. 2 is a side view of a nozzle assembly unit cell shown
in FIG. 1; and
[0035] FIG. 3 is a perspective of the nozzle assembly shown in FIG.
2.
DETAILED DESCRIPTION
Sulfonated Dye Salts
[0036] As used herein, the term "sulfonated dye" refers to any dye
molecule bearing a sulfonate group. Sulfonated dyes are a
well-known class of compound. Examples of some commercially
available sulfonated dyes are Food Black 1 (Brilliant Black BN),
Food Black 2 (Black 7984), Allura Red AC, Amaranth, Amido Black,
Food Red 3 (Azorubine), Food Brown 3 (Brown HT), Chrysoine
resorcinol (Resorcinol Yellow), Congo Red, Food Yellow 2 (Fast
Yellow), Hydroxynaphthol Blue, Lithol Rubine BK, Pigment Rubine,
Orange B, Orange G, Orange GGN, Food Red 7, Acid Red 1 (Red 2G),
Food Red 2, Orange Yellow S, Sunset Yellow, tartrazine, Yellow 2G,
Food Blue 2, Food Green S, Food Green 2, Food Blue 5, and
sulfonated phthalocyanines (e.g. copper phthalocyanine, Aldrich
Catalogue No. 41, 205-8). The Applicant has previously described
sulfonated phthalocyanine IR dyes, such as sulfonated
naphthalocyanines (see U.S. Pat. Nos. 7,148,345 and 7,122,076).
[0037] As used herein, the term "phthalocyanine" refers to any
compound belonging to the general class of macrocyclic
phthalocyanines, and includes naphthalocyanines,
quinolinephthalocyanines etc, as well as substituted derivatives
thereof.
[0038] As used herein, the term "IR-absorbing dye" means a
substance, which absorbs infrared radiation and which is therefore
suitable for detection by an infrared sensor. Preferably, the
IR-absorbing dye absorbs in the near infrared region, and
preferably has a .sub.max in the range of 700 to 1000 nm, more
preferably 750 to 900 nm, more preferably 780 to 850 nm. Dyes
having a .sub.max in this range are particularly suitable for
detection by semiconductor lasers, such as a gallium aluminium
arsenide diode laser.
[0039] Typically in the prior art, sulfonated dyes are provided in
their salt form. The usual salts of sulfonated dyes are sodium
salts, lithium salts, potassium salts and calcium salts. Such salts
are inexpensive, readily soluble in aqueous-based media and easy to
prepare. However, these salts suffer from severe kogation,
particularly salts of sulfonated phthalocyanines used in the
Applicant's Memjet.RTM. printers.
[0040] By contrast, the ammonium salts according to the present
invention, where the ammonium cation comprises at least 3 hydroxyl
groups, exhibit reduced kogation compared to, for example, sodium
salts.
[0041] Preferably, the ammonium cation comprises at least 5
hydroxyl groups. An example of such a cation is protonated
"bis-tris" (protonated
2,2-bis(hydroxymethyl)-2,2',2''-nitrilotriethanol), which exhibits
vastly reduced kogation compared to sodium salts. "Bis-tris", which
comprises 5 hydroxyl groups, also exhibits reduced kogation
compared to, for example, triethanolamine which comprises 3
hydroxyl groups.
[0042] In the most general form of the present invention, the dye
may be any sulfonated dye, such as those commonly used in printing
inks. These include Food dyes, sulfonated phthalocyanines,
sulfonated azo dyes and the like.
[0043] The present invention has been shown to work particularly
well with sulfonated phthalocyanines, which include sulfonated
naphthalocyanines. Sulfonated phthalocyanine dyes may be metal-free
or may comprise a central metal atom moiety M. Optionally, M is
selected from Si(A.sup.1)(A.sup.2), Ge(A.sup.1)(A.sup.2),
Ga(A.sup.1), Mg, Al(A.sup.1), TiO, Ti(A.sup.1)(A.sup.2), ZrO,
Zr(A.sup.1)(A.sup.2), VO, V(A.sup.1)(A.sup.2), Mn, Mn(A.sup.1), Fe,
Fe(A.sup.1), Co, Ni, Cu, Zn, Sn, Sn(A.sup.1)(A.sup.2), Pb,
Pb(A.sup.1)(A.sup.2), Pd and Pt. Phthalocyanines having a range of
central metal atom moieties are well known in the literature (see,
for example, Aldrich Catalogue). Copper phthalocyanine
tetrasulfonate is a particularly well known example, used in cyan
inkjet dyes. Sulfonation of phthalocyanines is readily achievable
using standard sulfonation chemistry.
[0044] Optionally, M is selected from Si(A.sup.1)(A.sup.2),
Ge(A.sup.1)(A.sup.2), Ga(A.sup.1), Al(A.sup.1), VO, Mn,
Mn(A.sup.1), Cu, Zn, Sn, and Sn(A.sup.1)(A.sup.2). S
[0045] Optionally, M is Ga(A.sup.1).
[0046] A.sup.1 and A.sup.2 are axial ligands, which may be the same
or different. Optionally, A.sup.1 and A.sup.2 and are selected from
--OH, halogen or --OR.sup.3. Optionally, A.sup.1 and A.sup.2 may be
--OC(O)R.sup.4 or --O(CH.sub.2CH.sub.2O).sub.eR.sup.e wherein e is
an integer from 2 to 10 and Re is H, C.sub.1-8 alkyl or
--C(O)C.sub.1-8 alkyl. Typically A.sup.1 is a hydroxyl group
(--OH).
[0047] R.sup.3 may be C.sub.1-20 alkyl, C.sub.5-12 aryl, C.sub.5-20
arylalkyl or Si(R.sup.x)(R.sup.y)(R.sup.z).
[0048] R.sup.4 may be C.sub.1-20 alkyl, C.sub.5-12 aryl or
C.sub.5-20 arylalkyl.
[0049] R.sup.x, R.sup.y and R.sup.z may be the same or different
and are selected from C.sub.1-12 alkyl, C.sub.5-12 aryl, C.sub.5-12
arylalkyl, C.sub.1-12 alkoxy, C.sub.5-12 aryloxy or C.sub.5-12
arylalkoxy.
[0050] An example of a sulfonated phthalocyanine dye salt, which
may be used in the present invention is shown in formula (I):
##STR00005##
wherein: Q.sup.1, Q.sup.2, Q.sup.3 and Q.sup.4 are the same or
different and are independently selected from a C.sub.3-20 arylene
group or a C.sub.3-20 heteroarylene group (e.g. C.sub.4 arylene to
provide typical phthalocyanines or C.sub.8 arylene to provide
naphthalocyanines); M is (H.sub.2) or a metal selected from the
group comprising: Si(A.sup.1)(A.sup.2), Ge(A.sup.1)(A.sup.2),
Ga(A.sup.1), Mg, Al(A.sup.1), TiO, Ti(A.sup.1)(A.sup.2), ZrO,
Zr(A.sup.1)(A.sup.2), VO, V(A.sup.1)(A.sup.2), Mn, Mn(A.sup.1), Fe,
Fe(A.sup.1), Co, Ni, Cu, Zn, Sn, Sn(A.sup.1)(A.sup.2), Pb,
Pb(A.sup.1)(A.sup.2), Pd and Pt; A.sup.1 and A.sup.2 are axial
ligands, which may be the same or different, and are selected from
the group comprising: --OH, halogen, --OR.sup.3, --OC(O)R.sup.4 and
--O(CH.sub.2CH.sub.2O).sub.eR.sup.e wherein e is an integer from 2
to 10 and R.sup.e is H, C.sub.1-8 alkyl or --C(O)C.sub.1-8 alkyl;
R.sup.3 is C.sub.1-20 alkyl, C.sub.5-12 aryl, C.sub.5-20 arylalkyl
or Si(R.sup.x)(R.sup.y)(R.sup.z); R.sup.4 is C.sub.1-20 alkyl,
C.sub.5-12 aryl or C.sub.5-20 arylalkyl; R.sup.x, R.sup.Y and
R.sup.z are the same or different and are selected from C.sub.1-12
alkyl, C.sub.5-12 aryl, C.sub.5-12 arylalkyl, C.sub.1-12 alkoxy,
C.sub.5-12 aryloxy or C.sub.5-12 arylalkoxy; and Z.sub.1.sup.+,
Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ are independently
selected from the group comprising: H and an ammonium cation
comprising at least 3 hydroxyl groups, wherein at least one of
Z.sub.1.sup.+, Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ is
said ammonium cation.
[0051] Usually, either three of Z.sub.1.sup.+, Z.sub.2.sup.+,
Z.sub.3.sup.+ and Z.sub.4.sup.+ or all of Z.sub.1.sup.+,
Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ are the ammonium
cation, depending on the exact nature of the cation and the method
of salt precipitation used in the preparation.
[0052] Optionally, Q.sup.1, Q.sup.2, Q.sup.3 and Q.sup.4 are the
same and are each a C.sub.4-10 arylene group (e.g. phthalocyanines
and naphthalocyanines). Q.sup.1, Q.sup.2, Q.sup.3 and Q.sup.4 may,
of course, be substituted in accordance with the optional aryl
substituents described below.
[0053] The general synthesis of phthalocyanines in accordance with
formula (I) are described in, for example, the Applicant's earlier
U.S. Pat. Nos. 7,148,345 and 7,122,076, the contents of which are
herein incorporated by reference. Specific salt syntheses are
described hereinbelow.
[0054] Optionally, the groups represented as Q.sup.1, Q.sup.2,
Q.sup.3 and Q.sup.4 are each selected from an arylene group of
formula (I) or (ii) below:
##STR00006##
wherein: R.sup.1 and R.sup.2 may be the same or different and are
selected from hydrogen, hydroxyl, C.sub.1-12 alkyl, C.sub.1-12
alkoxy, amino, C.sub.1-12 alkylamino, di(C.sub.1-12 alkyl)amino,
halogen, cyano, thiol, C.sub.1-12 alkylthio, C.sub.5-12 arylthio,
nitro, carboxy, C.sub.1-12 alkylcarbonyl, C.sub.1-12
alkoxycarbonyl, C.sub.1-12 alkylcarbonyloxy or C.sub.1-12
alkylcarbonylamino; and
Z.sup.+=Z.sub.1.sup.+, Z.sub.2.sup.+, Z.sub.3.sup.+ or
Z.sub.4.sup.+.
[0055] A more specific example of a sulfonated dye salt, which may
be used in the present invention is the sulfonated naphthalocyanine
salt shown in formula (II):
##STR00007##
wherein M is (H.sub.2) or a metal selected from the group
comprising: Si(A.sup.1)(A.sup.2), Ge(A.sup.1)(A.sup.2),
Ga(A.sup.1), Mg, Al(A.sup.1), TiO, Ti(A.sup.1)(A.sup.2), ZrO,
Zr(A.sup.1)(A.sup.2), VO, V(A.sup.1)(A.sup.2), Mn, Mn(A.sup.1), Fe,
Fe(A.sup.1), Co, Ni, Cu, Zn, Sn, Sn(A.sup.1)(A.sup.2), Pb,
Pb(A.sup.1)(A.sup.2), Pd and Pt; A.sup.1 is an axial ligand
selected from --OH, halogen, --OR.sup.3, --OC(O)R.sup.4 or
--O(CH.sub.2CH.sub.2O).sub.eR.sup.e wherein e is an integer from 2
to 10 and R.sup.e is H, C.sub.1-8 alkyl or C(O)C.sub.1-8 alkyl;
R.sup.3 is selected from C.sub.1-12 alkyl, C.sub.5-12 aryl,
C.sub.5-12 arylalkyl or Si(R.sup.x)(R.sup.y)(R.sup.z); R.sup.4 is
selected from C.sub.1-12 alkyl, C.sub.5-12 aryl or C.sub.5-12
arylalkyl; R.sup.x, R.sup.y and R.sup.z may be the same or
different and are selected from C.sub.1-12 alkyl, C.sub.5-12 aryl,
C.sub.5-12 arylalkyl, C.sub.1-12 alkoxy, C.sub.5-12 aryloxy or
C.sub.5-12 arylalkoxy; and Z.sub.1.sup.+, Z.sub.2.sup.+,
Z.sub.3.sup.+ and Z.sub.4.sup.+ are independently selected from the
group comprising: H and an ammonium cation comprising at least 3
hydroxyl groups, wherein at least one of Z.sub.1.sup.+,
Z.sub.2.sup.+, Z.sub.3.sup.+ and Z.sub.4.sup.+ is said ammonium
cation. Typically, Z.sub.1.sup.+=H; and
Z.sub.2.sup.+=Z.sub.3.sup.+=Z.sub.4.sup.+=the ammonium cation
comprising at least 3 hydroxyl groups. Alternatively,
Z.sub.1.sup.+=Z.sub.2.sup.+=Z.sub.3.sup.+=Z.sub.4.sup.+=the
ammonium cation comprising at least 3 hydroxyl groups.
Optionally, M is Ga(OH).
[0056] The term "aryl" is used herein to refer to an aromatic
group, such as phenyl, naphthyl or triptycenyl. C.sub.6-12 aryl,
for example, refers to an aromatic group having from 6 to 12 carbon
atoms, excluding any substituents. The term "arylene", of course,
refers to divalent groups corresponding to the monovalent aryl
groups described above. Any reference to aryl implicitly includes
arylene, where appropriate.
[0057] The term "heteroaryl" refers to an aryl group, where 1, 2, 3
or 4 carbon atoms are replaced by a heteroatom selected from N, O
or S. Examples of heteroaryl (or heteroaromatic) groups include
pyridyl, benzimidazolyl, indazolyl, quinolinyl, isoquinolinyl,
indolinyl, isoindolinyl, indolyl, isoindolyl, pyrrolyl, imidazolyl,
oxazolyl, isoxazolyl, pyrazolyl, isoxazolonyl, piperazinyl,
pyrimidinyl, pyridyl, pyrimidinyl, benzopyrimidinyl, benzotriazole,
quinoxalinyl, pyridazyl etc. The term "heteroarylene", of course,
refers to divalent groups corresponding to the monovalent
heteroaryl groups described above. Any reference to heteroaryl
implicitly includes heteroarylene, where appropriate.
[0058] Unless specifically stated otherwise, aryl and heteroaryl
groups may be optionally substituted with 1, 2, 3, 4 or 5 of the
substituents described below. The optional substituent(s) are
independently selected from C.sub.1-8 alkyl, C.sub.1-8 alkoxy,
--(OCH.sub.2CH.sub.2).sub.dOR.sup.d (wherein d is an integer from 2
to 5000 and R.sup.d is H, C.sub.1-8 alkyl or C(O)C.sub.1-8 alkyl),
cyano, halogen, amino, hydroxyl, thiol, --SR.sup.v,
--NR.sup.uR.sup.v, nitro, phenyl, phenoxy, --CO.sub.2R.sup.v,
--C(O)R.sup.v, --OCOR.sup.v, --SO.sub.2R.sup.v, --SO.sub.2R.sup.v,
--SO.sub.2OR.sup.v, --NHC(O)R.sup.v, --CONR.sup.uR.sup.v,
--CONR.sup.uR.sup.v, --SO.sub.2NR.sup.uR.sup.v, wherein R.sup.u and
R.sup.y are independently selected from hydrogen, C.sub.1-12 alkyl,
phenyl or phenyl-C.sub.1-8 alkyl (e.g. benzyl). Where, for example,
a group contains more than one substituent, different substituents
can have different R.sup.u or R.sup.v groups. For example, a
naphthyl group may be substituted with three substituents:
--SO.sub.2NHPh, --CO.sub.2Me group and --NH.sub.2.
[0059] The term "alkyl" is used herein to refer to alkyl groups in
both straight and branched forms. Unless stated otherwise, the
alkyl group may be interrupted with 1, 2, 3 or 4 heteroatoms
selected from O, NH or S. Unless stated otherwise, the alkyl group
may also be interrupted with 1, 2 or 3 double and/or triple bonds.
However, the term "alkyl" usually refers to alkyl groups having
double or triple bond interruptions. Where "alkenyl" groups are
specifically mentioned, this is not intended to be construed as a
limitation on the definition of "alkyl" above.
[0060] Where reference is made to, for example, C.sub.1-20 alkyl,
it is meant the alkyl group may contain any number of carbon atoms
between 1 and 20. Unless specifically stated otherwise, any
reference to "alkyl" means C.sub.1-20 alkyl, preferably C.sub.1-12
alkyl or C.sub.1-6 alkyl.
[0061] The term "alkyl" also includes cycloalkyl groups. As used
herein, the term "cycloalkyl" includes cycloalkyl, polycycloalkyl,
and cycloalkenyl groups, as well as combinations of these with
linear alkyl groups, such as cycloalkylalkyl groups. The cycloalkyl
group may be interrupted with 1, 2 or 3 heteroatoms selected from
O, N or S and may be specifically indicated as a heterocycloalkyl
group. Examples of heterocycloalkyl groups are pyrrolidino,
morpholino, piperidino etc. However, the term "cycloalkyl" usually
refers to cycloalkyl groups having no heteroatom interruptions.
Examples of cycloalkyl groups include cyclopentyl, cyclohexyl,
cyclohexenyl, cyclohexylmethyl and adamantyl groups.
[0062] The term "arylalkyl" refers to groups such as benzyl,
phenylethyl and naphthylmethyl.
[0063] The term "halogen" or "halo" is used herein to refer to any
of fluorine, chlorine, bromine and iodine. Usually, however,
halogen refers to chlorine or fluorine substituents.
[0064] Any chiral compounds described herein have not been given
stereo-descriptors. However, when compounds may exist in
stereoisomeric forms, then all possible stereoisomers and mixtures
thereof are included (e.g. enantiomers, diastereomers and all
combinations including racemic mixtures etc.).
[0065] Likewise, when compounds may exist in a number of
regioisomeric forms, then all possible regioisomers and mixtures
thereof are included.
[0066] For the avoidance of doubt, the term "a" (or "an"), in
phrases such as "comprising a", means "at least one" and not "one
and only one". Where the term "at least one" is specifically used,
this should not be construed as having a limitation on the
definition of "a".
[0067] Throughout the specification, the term "comprising", or
variations such as "comprise" or "comprises", should be construed
as including a stated element, integer or step, but not excluding
any other element, integer or step.
Inks
[0068] The dye salts described above may be formulated in inkjet
inks. Preferably, the inkjet ink is a water-based inkjet ink.
[0069] Water-based inkjet ink compositions are well known in the
literature and, in addition to water, may comprise additives, such
as co-solvents, biocides, sequestering agents, humectants,
viscosity modifiers, penetrants, wetting agents, surfactants
etc.
[0070] Co-solvents are typically water-soluble organic solvents.
Suitable water-soluble organic solvents include C.sub.1-4 alkyl
alcohols, such as ethanol, methanol, butanol, propanol, and
2-propanol; glycol ethers, such as ethylene glycol monomethyl
ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl
ether, ethylene glycol monomethyl ether acetate, diethylene glycol
monomethyl ether, diethylene glycol monoethyl ether, diethylene
glycol mono-n-propyl ether, ethylene glycol mono-isopropyl ether,
diethylene glycol mono-isopropyl ether, ethylene glycol
mono-n-butyl ether, diethylene glycol mono-n-butyl ether,
triethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl
ether, diethylene glycol mono-t-butyl ether,
1-methyl-1-methoxybutanol, propylene glycol monomethyl ether,
propylene glycol monoethyl ether, propylene glycol mono-t-butyl
ether, propylene glycol mono-n-propyl ether, propylene glycol
mono-isopropyl ether, dipropylene glycol monomethyl ether,
dipropylene glycol monoethyl ether, dipropylene glycol
mono-n-propyl ether, dipropylene glycol mono-isopropyl ether,
propylene glycol mono-n-butyl ether, and dipropylene glycol
mono-n-butyl ether; formamide, acetamide, dimethyl sulfoxide,
sorbitol, sorbitan, glycerol monoacetate, glycerol diacetate,
glycerol triacetate, and sulfolane; or combinations thereof.
[0071] Other useful water-soluble organic solvents include polar
solvents, such as 2-pyrrolidone, N-methylpyrrolidone, -caprolactam,
dimethyl sulfoxide, sulfolane, morpholine, N-ethylmorpholine,
1,3-dimethyl-2-imidazolidinone and combinations thereof.
[0072] The inkjet ink may contain a high-boiling water-soluble
organic solvent which can serve as a wetting agent or humectant for
imparting water retentivity and wetting properties to the ink
composition. Such a high-boiling water-soluble organic solvent
includes one having a boiling point of 180.degree. C. or higher.
Examples of the water-soluble organic solvent having a boiling
point of 180.degree. C. or higher are ethylene glycol, propylene
glycol, diethylene glycol, pentamethylene glycol, trimethylene
glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol,
2-methyl-2,4-pentanediol, tripropylene glycol monomethyl ether,
dipropylene glycol monoethyl glycol, dipropylene glycol monoethyl
ether, dipropylene glycol monomethyl ether, dipropylene glycol,
triethylene glycol monomethyl ether, tetraethylene glycol,
triethylene glycol, diethylene glycol monobutyl ether, diethylene
glycol monoethyl ether, diethylene glycol monomethyl ether,
tripropylene glycol, polyethylene glycols having molecular weights
of 2000 or lower, 1,3-propylene glycol, isopropylene glycol,
isobutylene glycol, 1,4-butanediol, 1,3-butanediol,
1,5-pentanediol, 1,6-hexanediol, glycerol, erythritol,
pentaerythritol and combinations thereof.
[0073] The total water-soluble organic solvent content in the
inkjet ink is preferably about 5 to 50% by weight, more preferably
10 to 30% by weight, based on the total ink composition.
[0074] Other suitable wetting agents or humectants include
saccharides (including monosaccharides, oligosaccharides and
polysaccharides) and derivatives thereof (e.g. maltitol, sorbitol,
xylitol, hyaluronic salts, aldonic acids, uronic acids etc.)
[0075] The inkjet ink may also contain a penetrant for accelerating
penetration of the aqueous ink into the recording medium. Suitable
penetrants include polyhydric alcohol alkyl ethers (glycol ethers)
and/or 1,2-alkyldiols. Examples of suitable polyhydric alcohol
alkyl ethers are ethylene glycol monomethyl ether, ethylene glycol
monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol
monomethyl ether acetate, diethylene glycol monomethyl ether,
diethylene glycol monoethyl ether, ethylene glycol mono-n-propyl
ether, ethylene glycol mono-isopropyl ether, diethylene glycol
mono-isopropyl ether, ethylene glycol mono-n-butyl ether,
diethylene glycol mono-n-butyl ether, triethylene glycol
mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene
glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene
glycol monomethyl ether, propylene glycol monoethyl ether,
propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl
ether, propylene glycol mono-isopropyl ether, dipropylene glycol
monomethyl ether, dipropylene glycol monoethyl ether, dipropylene
glycol mono-n-propyl ether, dipropylene glycol mono-isopropyl
ether, propylene glycol mono-n-butyl ether, and dipropylene glycol
mono-n-butyl ether. Examples of suitable 1,2-alkyldiols are
1,2-pentanediol and 1,2-hexanediol. The penetrant may also be
selected from straight-chain hydrocarbon diols, such as
1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,
1,7-heptanediol, and 1,8-octanediol. Glycerol or urea may also be
used as penetrants.
[0076] The amount of penetrant is preferably in the range of 1 to
20% by weight, more preferably 1 to 10% by weight, based on the
total ink composition.
[0077] The inkjet ink may also contain a surface active agent,
especially an anionic surface active agent and/or a nonionic
surface active agent. Useful anionic surface active agents include
sulfonic acid types, such as alkanesulfonic acid salts,
-olefinsulfonic acid salts, alkylbenzenesulfonic acid salts,
alkylnaphthalenesulfonic acids, acylmethyltaurines, and
dialkylsulfosuccinic acids; alkylsulfuric ester salts, sulfated
oils, sulfated olefins, polyoxyethylene alkyl ether sulfuric ester
salts; carboxylic acid types, e.g., fatty acid salts and
alkylsarcosine salts; and phosphoric acid ester types, such as
alkylphosphoric ester salts, polyoxyethylene alkyl ether phosphoric
ester salts, and glycerophosphoric ester salts. Specific examples
of the anionic surface active agents are sodium
dodecylbenzenesulfonate, sodium laurate, and a polyoxyethylene
alkyl ether sulfate ammonium salt.
[0078] Suitable nonionic surface active agents include ethylene
oxide adduct types, such as polyoxyethylene alkyl ethers,
polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters,
and polyoxyethylene alkylamides; polyol ester types, such as
glycerol alkyl esters, sorbitan alkyl esters, and sugar alkyl
esters; polyether types, such as polyhydric alcohol alkyl ethers;
and alkanolamide types, such as alkanolamine fatty acid amides.
Specific examples of nonionic surface active agents are ethers such
as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl
ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene
alkylallyl ether, polyoxyethylene oleyl ether, polyoxyethylene
lauryl ether, and polyoxyalkylene alkyl ethers (e.g.
polyoxyethylene alkyl ethers); and esters, such as polyoxyethylene
oleate, polyoxyethylene oleate ester, polyoxyethylene distearate,
sorbitan laurate, sorbitan monostearate, sorbitan mono-oleate,
sorbitan sesquioleate, polyoxyethylene mono-oleate, and
polyoxyethylene stearate. Acetylene glycol surface active agents,
such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol,
3,6-dimethyl-4-octyne-3,6-diol or 3,5-dimethyl-1-hexyn-3-ol, may
also be used.
[0079] The inkjet ink may also include a biocide, such as benzoic
acid, dichlorophene, hexachlorophene, sorbic acid, hydroxybenzoic
esters, sodium dehydroacetate, 1,2-benthiazolin-3-one,
3,4-isothiazolin-3-one or 4,4-dimethyloxazolidine.
[0080] The inkjet ink may also contain a sequestering agent, such
as ethylenediaminetetraacetic acid (EDTA).
[0081] The inkjet ink may also contain a singlet oxygen quencher.
The presence of singlet oxygen quencher(s) in the ink reduces the
propensity for the IR-absorbing dye to degrade. The quencher
consumes any singlet oxygen generated in the vicinity of the dye
molecules and, hence, minimizes their degradation. An excess of
singlet oxygen quencher is advantageous for minimizing degradation
of the dye and retaining its IR-absorbing properties over time.
Preferably, the singlet oxygen quencher is selected from ascorbic
acid, 1,4-diazabicyclo-[2.2.2]octane (DABCO), azides (e.g. sodium
azide), histidine or tryptophan.
Substrates
[0082] As mentioned above, the dyes of the present invention are
especially suitable for use in Hyperlabel.TM. and Netpage systems.
Such systems are described in more detail below and in the patent
applications listed above, all of which are incorporated herein by
reference in their entirety.
[0083] In the case of Hyperlabel.TM. and Netpage application, the
IR dye is disposed on a substrate in the form of a coding pattern
readable by an optically imaging sensing device. An example of a
suitable coding pattern is described in U.S. Pat. No. 6,832,717,
the contents of which is herein incorporated by reference.
Typically, the coding pattern is disposed over a substantial
portion of an interface surface of the substrate (e.g. greater than
20%, greater than 50% or greater than 90% of the surface).
[0084] Preferably, the substrate is IR reflective so that the dye
disposed thereon may be read by a sensing device. The substrate may
be comprised of any suitable material such as plastics (e.g.
polyolefins, polyesters, polyamides etc.), paper, metal or
combinations thereof. The substrate may be laminated.
[0085] For netpage applications, the substrate is preferably a
paper sheet. For Hyperlabel.TM. applications, the substrate is
preferably a tag, a label, a packaging material or a surface of a
product item. Typically, tags and labels are comprised of plastics,
paper or combinations thereof.
Thermal Bubble-Forming Inkjet Printhead
[0086] As mentioned above, the dyes of the present invention are
especially suitable for use in the Applicant's thermal inkjet
("Memjet.RTM.") printheads. A brief description of a thermal inkjet
printhead now follows. Further details of such printheads may be
found in the cross-referenced patents and patent applications
listed above, which are incorporated herein by reference.
[0087] Referring to FIG. 1, there is shown a part of printhead
comprising a plurality of nozzle assemblies. FIGS. 2 and 3 show one
of these nozzle assemblies in side-section and cutaway perspective
views.
[0088] Each nozzle assembly comprises a nozzle chamber 24 formed by
MEMS fabrication techniques on a silicon wafer substrate 2. The
nozzle chamber 24 is defined by a roof 21 and sidewalls 22 which
extend from the roof 21 to the silicon substrate 2. As shown in
FIG. 1, each roof is defined by part of a nozzle plate 56, which
spans across an ejection face of the printhead. The nozzle plate 56
and sidewalls 22 are formed of the same material, which is
deposited by PECVD over a sacrificial scaffold of photoresist
during MEMS fabrication. Typically, the nozzle plate 56 and
sidewalls 21 are formed of a ceramic material, such as silicon
dioxide or silicon nitride. These hard materials have excellent
properties for printhead robustness, and their inherently
hydrophilic nature is advantageous for supplying ink to the nozzle
chambers 24 by capillary action.
[0089] Returning to the details of the nozzle chamber 24, it will
be seen that a nozzle opening 26 is defined in a roof of each
nozzle chamber 24. Each nozzle opening 26 is generally elliptical
and has an associated nozzle rim 25. The nozzle rim 25 assists with
drop directionality during printing as well as reducing, at least
to some extent, ink flooding from the nozzle opening 26. The
actuator for ejecting ink from the nozzle chamber 24 is a heater
element 29 positioned beneath the nozzle opening 26 and suspended
across a pit 8.
[0090] Typically, the heater element 29 is comprised of a titanium
nitride or a nitride of a titanium alloy. An example of titanium
alloy nitride is titanium aluminium nitride. However, it will be
appreciated that other materials may be used as the heater element
29, and the present invention is not restricted to those materials
specifically recited herein.
[0091] Current is supplied to the heater element 29 via electrodes
9 connected to drive circuitry in underlying CMOS layers of the
substrate 2. When a current is passed through the heater element
29, it rapidly superheats surrounding ink to form a gas bubble,
which forces ink through the nozzle opening. By suspending the
heater element 29, it is completely immersed in ink when the nozzle
chamber 24 is primed. This improves printhead efficiency, because
less heat dissipates into the underlying substrate 2 and more input
energy is used to generate a bubble.
[0092] The heater element 29 shows less kogation using inks in
accordance with the present invention, when compared with inks
comprising, for example, sodium salts of sulfonated dyes. Less
kogation is observed after about 20 million drop ejections, about
30 million drop ejections, about 40 million drop ejections or about
50 million drop ejections.
[0093] Consequently, the lifetime of the printhead is increased by
at least 2-fold, at least 3-fold, at least 4-fold or at least
5-fold when compared with inks comprising sodium salts of
sulfonated dyes.
[0094] As seen most clearly in FIG. 1, the nozzles are arranged in
rows and an ink supply channel 27, extending longitudinally along
the row, supplies ink to each nozzle in the row. The ink supply
channel 27 delivers ink to an ink inlet passage 15 for each nozzle,
which supplies ink from the side of the nozzle opening 26 via an
ink conduit 23 in the nozzle chamber 24.
[0095] A MEMS fabrication process for manufacturing such printheads
was described in detail in U.S. application Ser. No. 11/246,684
filed on Oct. 11, 2005, the contents of which is herein
incorporated by reference.
[0096] The invention will now be described with reference to the
following examples. However, it will of course be appreciated that
this invention may be embodied in many other forms without
departing from the scope of the invention, as defined in the
accompanying claims.
EXAMPLES
[0097] In our earlier U.S. Pat. No. 7,148,345 and U.S. Patent
Application No. 60/851,754 (Attorney Docket No. IRB022US, filed on
Oct. 16, 2006), the contents of which are herein incorporated by
reference, we described the preparation of various salts of gallium
naphthalocyanine tetrasulfonic acid 1. The skilled person will
readily appreciate that salts according to the present invention
may be readily prepared from corresponding sulfonic acids by
conventional methods.
[0098] In testing a range of alternative salts, including those of
the alkali metals it was unexpectedly found that when the salt of
acid 1 comprises protonated "bis-tris"
[2,2-bis(hydroxymethyl)-2,2',2''-nitrilotriethanol] 2 as the
counterion, kogation on TiAlN heaters is greatly reduced and the
effective lifetime of a thermal inkjet printhead is increased by at
least 3-5-fold.
##STR00008##
[0099] A further advantage of the protonated bis-tris counterion is
that it greatly facilitates the preparation and isolation of the
corresponding salt of the acid 1. In general, salts of acid 1 are
conveniently prepared by mixing an amine or metal hydroxide with
the acid in methanol/water (ca. 80:20), diluting with a fixed
amount of ethyl acetate and filtering the product. Most of the
salts, especially the alkali metal salts, precipitate as fine
solids that are slow to filter, clogging membranes easily. However,
in the case of bis-tris salts, these have a lower solubility in the
reaction medium and flocculate readily to afford a much coarser
precipitate that filters easily. This lower solubility causes the
product to precipitate and stop at the tris(bis-tris) inner salt
(3) stage rather than proceed on to the tetrakis(bis-tris) salt (4)
form.
##STR00009##
Example 1
Preparation of the bis-tris Salt (3)
[0100] Bis-tris 2 (26.3 g; 0.125 mol, 7 equiv.) was dissolved
completely in methanol (150 mL) and water (40 mL) and then gallium
naphthalocyanine tetrasulfonic acid 1 (20.1 g; 0.018 mol) was added
with stirring to give a green suspension. The reaction mixture was
allowed to stir for 20 h and then ethyl acetate (350 mL) was added.
After stirring for another 10 min. the reaction mixture was poured
into ethyl acetate (250 mL) in a 2 L conical flask with vigorous
stirring. The precipitated salt was filtered off on a sintered
glass funnel under gravity, the filtrate draining readily at a fast
rate. The moist solid was then washed with methanol (4.times.50 mL)
under gravity and then the last traces were removed by suction. The
resulting solid was air-dried before being dried under high vacuum
at 65.degree. C. The bis-tris salt was obtained as a green powder
(23.7 g; 76%).
Example 2
Formulation of IR Inks
##STR00010##
[0101] Dye salts 5 and 6 were prepared similarly to salt 3 prepared
in Example 1. Each IR dye salt (3, 5, 6) was formulated according
to the components listed in Table 1 and filtered through a 0.2
.mu.m PTFE filter membrane.
TABLE-US-00002 TABLE 1 Composition of an ink vehicle used for
making up IR inks containing IR dye at 4 mM Ink component % w/w
ethylene glycol 5-15 1-propanol 5-15 2-pyrrolidinone 5-15 biocide
0.2 water balance
Example 3
Kogation Testing
[0102] Each IR ink containing the respective dye salt (3, 5 or 6)
was printed using the thermal inkjet printhead described in
connection with FIGS. 1-3. The heater elements 29 were observed
under high magnification after 50 million actuations.
[0103] The ink containing the sodium salt 6 performed the worst and
a high degree of kogation was observed after 50 million actuations.
The ink containing the triethanolamine salt 5 performed better than
the sodium salt 6, although a moderate amount of kogation was still
observed after 50 million actuations. However, the ink containing
the "bis-tris" salt 3 performed excellently with minimal or no
kogation observed after 50 million actuations.
[0104] It will be appreciated by ordinary workers in this field
that numerous variations and/or modifications may be made to the
present invention as shown in the specific embodiments without
departing from the spirit or scope of the invention as broadly
described. The present embodiments are, therefore, to be considered
in all respects to be illustrative and not restrictive.
* * * * *