Phase change hot melt ink compositions

An ink composition comprised of a colorant and a reversible crosslinked component vehicle obtained from the reaction product of an anhydride and an organoamine, and which ink possesses a viscosity of from about 1 centipoise to about 25 centipoise at a temperature of from about 125.degree. C. to about 185.degree. C.

REFERENCE TO COPENDING PATENT APPLICATIONS 
Hot melt inks are illustrated in copending patent applications U.S. Ser. 
No. 624,154, U.S. Ser. No. 624,157, U.S. Ser. No. 624,156, U.S. Ser. No. 
624,273, and U.S. Ser. No. 641,866, the disclosures of each being totally 
incorporated herein by reference. 
BACKGROUND OF THE INVENTION 
The present invention is directed to ink compositions and, more 
specifically, the present invention relates to hot melt inks especially 
useful for acoustic ink printing, processes and apparatuses, reference for 
example U.S. Pat. No. 5,121,141, U.S. Pat. No. 5,111,220, U.S. Pat. No. 
5,128,726, U.S. Pat. No. 5,371,531, the disclosures of which are totally 
incorporated herein by reference, including especially acoustic ink 
processes as illustrated in some of the aforementioned copending 
applications and patents, such as an acoustic ink printer for printing 
images on a record medium. 
More specifically, the present invention is directed to hot melt acoustic 
ink compositions wherein there can be generated with such inks excellent 
developed images with acceptable image permanence, excellent projection 
efficiency on transparencies without a post fusing step, and excellent 
crease resistance, and wherein the inks possess acceptable, and in 
embodiments superior lightfastness and superior waterfastness. Moreover, 
in embodiments of the present invention there is enabled the elimination, 
or minimization of undesirable paper curl since water is not present, or 
very small amounts thereof are selected, in the invention inks, and it is 
preferred that there be an absence of water, and since water is not 
present in the inks a dryer can be avoided thereby minimizing the cost of 
the acoustic ink jet apparatus and process. The inks of the present 
invention in embodiments thereof are comprised of a colorant and a 
vehicle, and more specifically, wherein the vehicle is a reversible 
crosslinked component, that is for example a resin that possesses a low 
viscosity at high temperatures and excellent mechanical characteristics 
after being selected for printing, or wherein the ink vehicle is a liquid 
at high temperatures to enable, for example, a low ink viscosity for 
jetting, and be resin like in its characteristics after jetting to enable 
excellent fixing properties, and which vehicle is obtained from the 
reaction of an anhydride and a diamine or a triamine. The reversible 
crosslinked vehicle can exist as a mixture of an imido amine and a 
polyamide resin, and wherein the equilibria favors a mixture of 
predominately the imido amine at low temperatures such as from about 
20.degree. C. to about 120.degree. C., and predominately a polyamide at 
higher temperatures such as from about 125.degree. C. to about 180.degree. 
C. 
PRIOR ART 
In acoustic ink printing, the printhead produces approximately 2.2 
picoliter droplets by an acoustic energy process. The ink under these 
conditions should display a melt viscosity of about 5 centipoise or less 
at the jetting temperature. Furthermore, once the ink is jetted onto the 
paper, the ink image should be of excellent crease property, and should be 
nonsmearing waterfast, of excellent transparency and excellent fix 
qualities. In selecting an ink for such applications, it is desirable that 
the vehicle display a low melt viscosity, such as from about 1 centipoise 
to about 25 centipoise in the acoustic head, while also displaying solid 
like properties after being jetted onto paper. Since the acoustic head can 
tolerate a temperature up to about 180.degree. C., and preferably up to a 
temperature of from about 140.degree. C. to about 160.degree. C., the 
vehicle for the ink should preferably display liquid like properties, such 
as a viscosity of 1 to about 10 centipoise, at a temperature of from about 
125.degree. C. to about 165.degree. C., and solidify or harden after 
jetting onto paper such that the ink displays a hardness value of from 
about 0.1 to about 0.5 millimeter utilizing a penetrometer according to 
the ASTM penetration method D1321. 
Ink jet printing processes that employ inks that are solid at room 
temperature and liquid at elevated temperatures are known. For example, 
U.S. Pat. No. 4,490,731, the disclosure of which is totally incorporated 
herein by reference, discloses an apparatus for dispensing certain solid 
inks for printing on a substrate such as paper. The ink dye vehicle is 
chosen to have a melting point above room temperature so that the ink, 
which is melted in the apparatus, will not be subject to evaporation or 
spillage during periods of nonprinting. The vehicle selected possesses a 
low critical temperature to permit the use of the solid ink in a thermal 
ink jet printer. In thermal ink jet printing processes employing hot melt 
inks, the solid ink is melted by a heater in the printing apparatus and 
utilized as a liquid in a manner similar to that of conventional thermal 
ink jet printing. Upon contact with the printing substrate, the molten ink 
solidifies rapidly, enabling the dye to remain on the surface instead of 
being carried into the paper by capillary action, thereby attempting to 
enable higher print density than is generally obtained with liquid inks. 
Hot melt ink jets are somewhat similar to thermal ink jets, however, a hot 
melt ink contains no solvent. Thus, rather than being liquid at room 
temperature, a hot melt ink is typically a solid or semi-solid having a 
wax-like consistency. These inks usually need to be heated, for example, 
to approximately 100.degree. C. before the ink melts and turns into a 
liquid. With hot melt inks, a plurality of ink jet nozzles are provided in 
a printhead. A piezoelectric vibrating element is located in each ink 
channel upstream from a nozzle so that the piezoelectric oscillations 
propel ink through the nozzle. After the hot melt ink is applied to the 
substrate, the ink is resolidified by freezing on the substrate. 
Each of these types of known ink jets, however, has a number of advantages 
and disadvantages. One advantage of thermal ink jets is their compact 
design for the integrated electronics section of the printhead. Thermal 
ink jets are disadvantageous in that the thermal ink has a tendency to 
soak into a plain paper medium. This blurs the print or thins out the 
print locally thereby adversely affecting print quality. Problems have 
been encountered with thermal ink jets in attempting to rid the ink of 
moisture fast enough so that the ink does not soak into a plain paper 
medium. This is particularly true when printing with color. Therefore, 
usually when printing with thermal ink, one needed to use coated papers, 
which are more expensive than plain paper. 
One advantage of a hot melt ink jet is its ability to print on plain paper 
since the hot melt ink quickly solidifies as it cools and, since it is 
waxy in nature, does not normally soak into a paper medium. However, hot 
melt ink jets can be cumbersome in structure and in design, that is, the 
associated integrated electronics of a thermal ink jet head are 
considerably more compact than those of a hot melt ink jet head. 
In addition, U.S. Pat. No. 4,751,528, the disclosure of which is totally 
incorporated herein by reference, discloses a hot melt ink jet system 
which includes a temperature-controlled platen provided with a heater and 
a thermoelectric cooler electrically connected to a heat pump and a 
temperature control unit for controlling the operation of the heater and 
the heat pump to maintain the platen temperature at a desired level. The 
apparatus also includes a second thermoelectric cooler to solidify hot 
melt ink in a selected zone more rapidly to avoid offset by a pinch roll 
coming in contact with the surface of the substrate to which hot melt ink 
has been applied. An airtight enclosure surrounding the platen is 
connected to a vacuum pump and has slits adjacent to the platen to hold 
the substrate in thermal contact with the platen. 
Further, U.S. Pat. No. 4,791,439, the disclosure of which is totally 
incorporated by reference, discloses an apparatus for use with hot melt 
inks having an integrally connected ink jet head and reservoir system, the 
reservoir system including a highly efficient heat conducting plate 
inserted within an essentially nonheat conducting reservoir housing. The 
reservoir system has a sloping flow path between an inlet position and a 
sump from which ink is drawn to the head, and includes a plurality of 
vanes situated upon the plate for rapid heat transfer. 
Ink compositions for ink jet printing are known. For example, U.S. Pat. No. 
4,840,674, the disclosure of which is totally incorporated herein by 
reference, discloses an ink composition which comprises a major amount of 
water, an organic solvent selected from the group consisting of 
tetramethylene sulfone, 1,1,3,3-tetramethyl urea, 3-methyl sulfolane, and 
1,3-dimethyl-2-imidazolidone, which solvent has permanently dissolved 
therein spirit soluble dyes. 
U.S. Pat. No. 5,006,170 and U.S. Pat. No. 5,122,187, the disclosures of 
each of which are totally incorporated herein by reference, disclose hot 
melt ink compositions suitable for ink jet printing which comprise a 
colorant, a binder, and a propellant such as hydrazine, cyclic amines, 
ureas, carboxylic acids, sulfonic acids, aldehydes, ketones, hydrocarbons, 
esters, phenols, amides, imides, halocarbons, and the like. The inks of 
the present invention are dissimilar than the aforementioned '170 and 
'187, in that, for example, the invention vehicle selected displays a 
viscosity of from about 1 to about 20, and preferably 10 centipoise when 
heated to a temperature of from about 125.degree. C. to about 165.degree. 
C., such that acoustic energy in the printhead can eject an ink droplet 
onto paper. Additionally, the vehicles of the present invention display 
softening points of from about 50.degree. C. to about 100.degree. C. 
U.S. Pat. No. 5,041,161, the disclosure of which is totally incorporated 
herein by reference, discloses an ink jet ink which is semi-solid at room 
temperature. The ink combines the advantageous properties of thermal phase 
inks and liquid inks. The inks comprise vehicles, such as glyceryl esters, 
polyoxyethylene esters, waxes, fatty acids, and mixtures thereof, which 
are semi-solid at temperatures between 20.degree. C. and 45.degree. C. The 
ink is impulse jetted at an elevated temperature in the range of about 
45.degree. C. to about 110.degree. C., at which temperature the ink has a 
viscosity of about 10 to 15 centipoise. The inks also contain 0.1 to 30 
weight percent of a colorant system. 
U.S. Pat. No. 4,853,036 and U.S. Pat. No. 5,124,718 disclose an ink for ink 
jet recording which comprises a liquid composition essentially comprising 
a coloring matter, a volatile solvent having a vapor pressure of 1 
millimeter Hg or more at 25.degree. C., and a material being solid at room 
temperature and having a molecular weight of 300 or more, and prepared so 
as to satisfy the formula B1/A1o3, assuming viscosity as A1 cP at 
25.degree. C., measured when the content of the solid material in the 
composition is 10 percent by weight, and assuming viscosity as B1 cP at 
25.degree. C., measured when the content of the solid material in the 
composition is 30 percent by weight. An ink jet recording process using 
the ink is also disclosed. 
SUMMARY OF THE INVENTION 
While the known ink compositions and processes may be suitable for their 
intended purposes, a need remains for acoustic hot melt ink compositions 
suitable for thermal ink jet printing. In addition, there is a need for 
hot melt ink compositions which are compatible with a wide variety of 
plain papers. Further, there is a need for hot melt ink compositions which 
generate high quality, waterfast images on plain papers. There is also a 
need for hot melt ink jet ink compositions which generate high quality, 
fast-drying images on a wide variety of plain papers at low cost with high 
quality text and high quality graphics. Further, there is a need for hot 
melt ink jet ink compositions which exhibit minimal feathering. 
Additionally, there is a need for hot melt ink jet ink compositions which 
exhibit minimal intercolor bleed. There is also a need for hot melt ink 
jet ink compositions which exhibit excellent image permanence. Further, 
there is a need for hot melt ink jet ink compositions which are suitable 
for use in acoustic ink jet printing processes. Additionally, there is a 
need for hot ink compositions suitable for ink jet printing processes 
wherein the substrate is heated prior to printing and is cooled to ambient 
temperature subsequent to printing (also known as heat and delay printing 
processes). There is also a need for ink compositions suitable for ink jet 
printing wherein high optical densities can be achieved with relatively 
low dye concentrations. A need also remains for ink compositions suitable 
for ink jet printing wherein curling of the substrate, such as paper, 
subsequent to printing is minimized, or avoided. These and other needs can 
be achievable with the inks of the present invention in embodiments 
thereof. 
Examples of objects of the present invention include, for example: 
It is an object of the present invention to provide hot melt ink 
compositions with many of the advantages illustrated herein. 
It is another object of the present invention to provide hot melt ink 
compositions suitable for acoustic ink jet printing. 
It is yet another object of the present invention to provide hot melt ink 
compositions which are compatible with a wide variety of plain papers. 
It is still another object of the present invention to provide hot melt ink 
compositions which generate high quality images on plain papers. 
Another object of the present invention is to provide hot melt ink jet ink 
compositions which are comprised of a colorant, preferably a dye, and 
vehicle comprised of a reversible crosslink material such as an organo 
amino-imide/polyamide equilibria mixture, and wherein in embodiments the 
inks possess a low viscosity of, for example, 5 to 20 at 160.degree. C. 
Yet another object of the present invention is to provide hot ink jet ink 
compositions which exhibit low viscosity of from about 1 to about 10 
centipoise at a temperature of from about 125.degree. C. to about 
160.degree. C. 
Still another object of the present invention is to provide hot melt ink 
jet ink compositions which exhibit minimal intercolor bleed. 
It is another object of the present invention to provide hot melt ink jet 
ink compositions which exhibit excellent image permanence. 
It is yet another object of the present invention to provide hot ink jet 
ink compositions that contain no water and which are suitable for use in 
acoustic ink jet printing processes. 
It is still another object of the present invention to provide hot ink 
compositions that contain no water and that are suitable for ink jet 
printing processes wherein the substrate is heated prior to printing and 
is cooled to ambient temperature subsequent to printing (also known as 
heat and delay printing processes). 
Another object of the present invention is to provide ink compositions 
suitable for ink jet printing wherein high optical densities can be 
achieved with relatively low dye concentrations. 
Yet another object of the present invention is to provide solvent free hot 
melt ink compositions suitable for ink jet printing wherein curling of the 
substrate subsequent to printing is minimized. 
Another object of the present invention resides in the provision of hot 
melt inks wherein the viscosity of the ink is from about 1 centipoise to 
about 10 centipoise at, for example, the jetting temperature which can be 
from about 125.degree. C. to about 180.degree. C., and preferably from 
about 160.degree. C. thereby enabling excellent jetting at reasonable 
power levels. 
Further, in another object of the present invention there are provided hot 
melt inks with no water and vehicles such as a reversible crosslinked 
vehicle, and a colorant such as a dye, or a pigment. 
Additionally, in another object of the present invention there are provided 
hot melt inks with no water or solvent for ink printing methods and 
apparatuses, and wherein a number of the advantages as illustrated herein 
are achievable. 
The present invention relates to an ink composition comprised of a colorant 
and a reversible crosslinked vehicle obtained from the reaction product of 
an anhydride and an organic amine, including diamines, triamines, 
tetraamines, or mixtures thereof, and which ink preferably possesses a 
viscosity of from about 1 centipoise to about 25 centipoise at a 
temperature of from about 125.degree. C. to about 185.degree. C.; and an 
ink composition wherein the crosslinked component is obtained from the 
reaction product of an anhydride and a diamine, resulting in an imido 
amine wherein the amino group undergoes a ring opening reaction with the 
imide to form a crosslinked amide, and optional known ink additives. 
DETAILED DESCRIPTION OF THE INVENTION 
In embodiments the ink compositions of the present invention comprise a dye 
or pigment, and a reversible crosslinked vehicle, and wherein the colorant 
is present in various effective amounts, such as from about 2 to about 10 
weight percent, and the vehicle is present in an amount of from about 60 
to about 90 weight percent. 
Embodiments of the present invention include an ink composition comprised 
of a dye, a reversible crosslinked vehicle obtained from the reaction of 
an anhydride and diamine or triamine, and resulting in the equilibria 
reaction mixture of an organoimide-amine and polyamide. 
Embodiments of the present invention include an ink composition comprised 
of a colorant and a reversible crosslinked component vehicle obtained from 
the reaction product of an anhydride and an organoamine, and which ink 
possesses a viscosity of from about 1 centipoise to about 25 centipoise at 
a temperature of from about 125.degree. C. to about 185.degree. C.; an ink 
composition wherein said reversible crosslinked vehicle is obtained from 
the reaction product of an anhydride like phthalic anhydride and an 
organoamine, such as a diamine or a triamine, and which reaction product 
results in a temperature dependent equilibria reaction mixture of an imido 
amine and polyamide of the structure 
##STR1## 
wherein R is hydrogen, alkyl, or alkenyl, each with from about 1 to about 
36 carbon atoms, and R.sub.1 is an alkylene or polyoxyalkylene, each with 
from about 2 to about 36 carbon atoms; an ink composition wherein the 
vehicle I or II is comprised of from about 75 to about 95 percent by 
weight of polyamide and from about 5 to about 25 percent by weight of 
imido amine at a temperature of from about 20.degree. C. to about 
100.degree. C., and the vehicle I or II is comprised of from about 75 to 
about 95 percent by weight of imido amine and from about 5 to about 25 
percent by weight of polyamide at a temperature of from about 120.degree. 
C. to about 160.degree. C.; an ink composition wherein the anhydride is 
selected from the group consisting of phthalic anhydride, 3-methylphthalic 
anhydride, succinic anhydride, 2-alkylsuccinic anhydride such as 
2-methylsuccinic anhydride, 2-ethylsuccinic anhydride, 2-propylsuccinic 
anhydride, 2-butylsuccinic anhydride, 2-octylsuccinic anhydride, 
2-stearylsuccinic anhydride, 2-octadecen-2yl-succinic anhydride, 
2-decen-2yl-succinic anhydride, and 2-dodecen-2yl-succinic anhydride; an 
ink composition wherein the polyamide possesses a molecular weight of from 
about 1,500 to about 15,000 grams per mole; an ink composition wherein the 
ink is a solid at room temperature, about 20.degree. C. to about 
40.degree. C.; an ink composition wherein said polyamide of I or II is 
present in an amount of from about 60 to about 99 weight percent at a 
temperature of from about 20.degree. C. to about 120.degree. C.; an ink 
composition wherein said polyamide of I or II is present in an amount of 
from about 85 to about 97 weight percent at a temperature of from about 
20.degree. C. to about 120.degree. C.; an ink composition wherein said 
imido amine of I or II is present in an amount of from about 60 to about 
99 weight percent at a temperature of from about 120.degree. C. to about 
165.degree. C.; an ink composition wherein said imido amine of I or II is 
present in an amount of from about 85 to about 97 weight percent at a 
temperature of from about 120.degree. C. to about 165.degree. C.; a 
printing process which comprises incorporating into an acoustic ink jet 
printer an ink comprised of a colorant and a crosslinked reversible 
vehicle obtained from the reaction product of an anhydride and an organic 
amine, and which ink possesses a viscosity of from about 1 centipoise to 
about 25 centipoise at a temperature of from about 125.degree. C. to about 
185.degree. C., a viscosity of from about 5 centipoise to about 20 
centipoise at a temperature of from about 125.degree. C. to about 
185.degree. C., and causing droplets of the ink to be ejected in imagewise 
pattern onto a substrate; a process which comprises (a) providing an 
acoustic ink printer having a pool of liquid ink with a free surface, and 
a printhead including at least one droplet ejector for radiating the free 
surface of said ink with focused acoustic radiation to eject individual 
droplets of ink therefrom on demand, said radiation being brought to focus 
with a finite waist diameter in a focal plane, said ink comprising a 
colorant and a reversible crosslinked resin obtained from the reaction 
product of an anhydride and an organic amine, and which ink possesses a 
viscosity of from about 1 centipoise to about 25 centipoise at a 
temperature of from about 125.degree. C. to about 185.degree. C., 
viscosity of from about 5 centipoise to about 20 centipoise at a 
temperature of from about 125.degree. C. to about 185.degree. C., and (b) 
causing droplets of said ink to be ejected onto a recording sheet in an 
imagewise pattern at a temperature of from about 120.degree. C. to about 
185.degree. C.; an ink composition wherein alkyl contains from 1 to 6 
carbon atoms; an ink composition wherein alkenyl contains from 1 to about 
10 carbon atoms; an ink composition wherein R.sub.1 is alkenyl with from 2 
to about 8 carbon atoms; an ink composition wherein the colorant is a 
pigment; and an ink composition wherein said organic amine is a 
tetraamine, a diamine, a triamine or mixtures thereof. 
The organic amine, preferably an organic diamine, can be selected from the 
group consisting of 1,2-diaminoethane, 1,2A diaminopropane, 
1,4-diaminobutane, 1,5-diaminopentane, 2Amethylpentylene diamine, 
1,6-diaminohexane, 1,8-diaminooctane, 1,10Adiaminodecane, 
1,12-diaminododecane, poly(oxyalkyleneoxy)-diamine available from Huntsman 
Corporation as JEFFAMINE.TM. 148, 230, 400, 192, 700 and 403, illustrated 
by the formula 
##STR2## 
wherein R is hydrogen or alkyl like CH.sub.3 ; and n is 2 to 21; and which 
diamine is utilized in an amount of, for example, from about 0.35 mole 
equivalent to about 0.65 mole equivalent of the vehicle. 
The anhydride utilized in the preparation of the reversible crosslink 
vehicle can be selected from the group consisting of phthalic anhydride, 
3-methylphthalic anhydride, succinic anhydride, 2-alkylsuccinic anhydride 
such as 2-methylsuccinic anhydride, 2-ethylsuccinic anhydride, 
2-propylsuccinic anhydride, 2-butylsuccinic anhydride, 2-octylsuccinic 
anhydride, 2-stearylsuccinic anhydride, 2-octadecen-2yl-succinic 
anhydride, 2-decen-2yl-succinic anhydride, 2-dodecen-2yl-succinic 
anhydride, mixtures thereof, and the like, including other known 
anhydrides, and which anhydride is utilized in an amount of, for example, 
about 0.35 mole equivalent to about 0.65 mole equivalent of the vehicle. 
Examples of the imido amines include N-aminododecyl phthalimide, 
N'-10-amino-decyl phthalimide, N'-8-amino-octyl phthalimide, 
N'-6-amino-hexyl phthalimide, N'-5-amino-pentyl phthalimide, 
N'-4-amino-butyl phthalimide, N'-3-amino-propyl phthalimide, 
N'-2-amino-ethyl phthalimide, N'-ethyloxyethylamine phthalimide, 
N'-ethyloxyethyloxyethylamine phthalimide, 
N'-ethyloxyethyloxyethyloxyethylamine phthalimide, 
N'-ethyloxyethyloxyethyloxyethyloxyethylamine phthalimide, 
N'-(polyethyloxy)ethylamine phthalimide, N'-(polypropyloxy)propylamine 
phthalimide, N'-12-aminododecyl 3-methylphthalimide, 
N'-(polyethyloxy)ethylamine 3-methylphthalimide, 
N'-(polypropyloxy)propylamine 3-methylphthalimide, N'-12-aminododecyl 
succinimide, N'-(polyethyloxy)ethylamine succinimide, 
N'-(polypropyloxy)propylamine succinimide, N'-12-aminododecyl 
2-octylsuccinimide, N'-(polyethyloxy)ethylamine 2-octylsuccinimide, 
N'-(polypropyloxy)propylamine 2-octylsuccinimide, N'-12-aminododecyl 
2-stearylsuccinimide, N'-(polyethyloxy)ethylamine 2-stearylsuccinimide, 
N'-(polypropyloxy)propylamine 2-stearylsuccinimide, 
N'-(polyethyloxy)ethylamine 2-octadecen-2yl-succinimide, 
N'-12-aminododecyl 2-octadecen-2yl-succinimide, N'-12-aminododecyl 
2-decen-2yl-succinimide, and N'-12-aminododecyl 2-dodecen-2yl-succinmide, 
and which amine is present in an effective amount of from about 60 to 
about 97 percent by weight of the ink at a temperature of from about 
120.degree. C. to about 165.degree. C. during jetting from the acoustic 
printing device onto paper, and present in an amount of from about 5 to 
about 35 percent by weight of the ink when the ink is on the paper or 
substrate, and cooled to a temperature of from about 20.degree. C. to 
about 45.degree. C. 
Examples of the polyamide include a crosslinked poly(N'-12-aminododecyl) 
phthalamide, crosslinked poly(N'-10-aminodecyl) phthalamide, crosslinked 
poly(N'-8-amino-octyl) phthalamide, crosslinked poly(N'-6-amino-hexyl) 
phthalamide, crosslinked poly(N'-5-amino-pentyl) phthalimade, crosslinked 
poly(N'-4-amino-butyl) phthalamide, crosslinked poly(N'-3-amino-propyl) 
phthalimide, crosslinked poly(N'-2-amino-ethyl) phthalamide, crosslinked 
poly(N'-ethyloxyethylamine) phthalamide, crosslinked 
poly(N'-ethyloxyethyloxyethylamine) phthalamide, crosslinked 
poly(N'-ethyloxyethyloxyethyloxyethylamine) phthalamide, crosslinked 
poly(N'-ethyloxyethyloxyethyloxyethyloxyethylamine) phthalamide, 
crosslinked poly(N'-(polyethyloxy)ethylamine) phthalamide, crosslinked 
poly(N'-(polypropyloxy)propylamine) phthalamide, crosslinked 
poly(N'-12-aminododecyl) 3-methylphthalamide, crosslinked 
poly(N'-(polyethyloxy)ethylamine) 3-methylphthalamide, crosslinked 
poly(N'-(polypropyloxy)propylamine) 3-methylphthalamide, crosslinked 
poly(N'-12-aminododecyl) succinamide, crosslinked 
poly(N'-(polyethyloxy)ethylamine) succinamide, crosslinked 
poly(N'-(polypropyloxy)propylamine) succinamide, crosslinked 
poly(N'-12-aminododecyl) 2-octylsuccinamide, crosslinked 
poly(N'-(polyethyloxy)ethylamine) 2-octylsuccinamide, crosslinked 
poly(N'-(polypropyloxy)propylamine) 2-octylsuccinamide, crosslinked 
poly(N'-12-aminododecyl) 2-stearylsuccinamide, crosslinked 
poly(N'-(polyethyloxy)ethylamine) 2-stearylsuccinamide, crosslinked 
poly(N'-(polypropyloxy)propylamine) 2-stearylsuccinamide, crosslinked 
poly(N'-(polyethyloxy)ethylamine) 2-octadecen-2yl-succinamide, crosslinked 
poly(N'-12-aminododecyl) 2-octadecen-2yl-succinamide, crosslinked 
poly(N'-12-aminododecyl) 2-decen-2yl-succinamide, and crosslinked 
poly(N'-12-aminododecyl) 2-dodecen-2yl-succinamide, and which polyamide is 
present in an effective amount of, for example, from about 5 to about 65 
percent by weight of the ink at a temperature of from about 120.degree. C. 
to about 165.degree. C. during jetting from the acoustic printing device 
onto paper, and which polyamide is, for example, present in an amount of 
from about 65 to about 97 percent by weight of the ink when the ink is on 
the paper or substrate and cooled to a temperature of from about 
20.degree. C. to about 45.degree. C. 
Examples of colorants, preferably dyes selected for the inks of the present 
invention, are known, reference the Color Index, and include those as 
illustrated in U.S. Pat. No. 5,310,887, the disclosure of which is totally 
incorporated herein by reference, and, for example, Resorcin Crystal 
Violet, Orasol Black RL or Intraplast Black RL/Solvent Black 29, Lapranol 
Black BR, Savinyl Black RLS, Orasol Black RLP, Neozapon Black X57; solvent 
yellow dyes inclusive of Savinyl Yellow 2 RLS, Savinyl Yellow RLSN, 
Intraplast Yellow 2GLN, Neozapon Yellow 081, Neozapon Yellow 141, Levaderm 
Lemon Yellow, Zapon Fast Yellow CGR, Aizen Fast Yellow CGNH, Zapon Yellow 
100, Zapon Yellow 157, and Savinyl Yellow RLS; magenta dyes such as 
Neozapon Red 492, Direct Brilliant Pink B, Savinyl Pink 6 BLS, Savinyl Red 
3 BLS, Orasol Red 2 BL, Intraplast Red G (Orasol Red), Savinyl Red BLSN, 
Savinyl Scarlet RLS, Savinyl Fire Red 3GLS, and Zapon Red 335; cyan dyes 
such as Orasol Blue 2 GLN, Neozapon Blue 807, Savinyl Blue RLS, Savinyl 
Blue GLS, Orasol Blue GN, and Losol Blue; brown dyes inclusive of Zapon 
Brown 187 and Savinyl Brown GLS, Solvent Green 3, Sudan Black B, Ceres 
Blue 2V, Liquid Oil Jet Black, Macrolex Red G Gram, Macrolex Yellow 3G, 
Victoria Blue R, available from Bayer AG, Leverkusen, Germany, Morfast 
Blue 100, Morfast Red 104, and Morfast Red 100, available from Morton 
International Specialty Chemicals Group, Chicago, Ill.; mixtures thereof; 
and the like with preferred dyes in embodiments including Reactint Black 
57AB, Reactint Black X40LV, Reactint Blue 17AB, Reactint Blue X3LV, 
Reactint Blue X19, Reactint Red X26B-50, Reactint Red X520, Reactint 
Violet X80LT, Reactint Orange X38, and Reactint Yellow X15, all available 
from Milliken Chemicals. Typically, the dye or pigment is present in the 
ink in an amount of from about 0.01 to about 10 percent by weight, 
preferably from about 0.05 to about 4 percent by weight, and more 
preferably from about 0.1 to about 3 percent by weight, although the 
amount can be outside these ranges. Specific pigment examples include 
carbon black, magenta, yellow, cyan pigments, or mixtures thereof selected 
in effective amounts of, for example, from 1 to about 10 weight percent. 
Optional ink additives include biocides, such as Dowicil 150, 200, and 75, 
benzoate salts, sorbate salts, and the like, present in effective amounts, 
such as for example an amount of from about 0.0001 to about 4 percent by 
weight, and preferably from about 0.01 to about 2.0 percent by weight; pH 
controlling agents such as acids; or bases, phosphate salts, carboxylates 
salts, sulfite salts, amine salts, and the like, present, for example, in 
an amount of from 0 to about 1 percent by weight and preferably from about 
0.01 to about 1 percent by weight, based on the weight of the ink 
components. 
The inks of the present invention are particularly suitable for printing 
processes wherein the substrate, such as paper, transparency material, or 
the like, is heated during the printing process to facilitate formation of 
the liquid crystalline phase within the ink. When transparency substrates 
are employed, temperatures typically are limited to a maximum of about 
100.degree. C. to about 110.degree. C., since the polyester typically 
employed as the base sheet in transparency sheets tends to deform at 
higher temperatures. Specially formulated transparencies and paper 
substrates can, however, tolerate higher temperatures, and frequently are 
suitable for exposure to temperatures of 150.degree. C. or even 
200.degree. C. in some instances. Typical heating temperatures are from 
about 40.degree. C. to about 140.degree. C., and preferably from about 
60.degree. C. to about 95.degree. C., although the temperature can be 
outside these ranges. 
The reversible crosslinked vehicle can be prepared by reacting an anhydride 
with an organic diamine compound by a condensation process. In one 
embodiment of this invention, the reversible crosslinked vehicle can be 
prepared, for example, by charging a reactor, such as a 300 milliliter 
Parr reactor equipped with a distillation apparatus, with from about 0.5 
mole equivalent of an anhydride, such as phthalic anhydride or succinic 
anhydride, with about 0.5 mole equivalent of an organic diamine such as 
1,12-dodecane diamine, and optionally a condensation catalyst, such as 
dibutylstannoic acid, at a temperature of from about 150.degree. C. to 
about 185.degree. C. with stirring for a duration of from about 3 to 6 
hours. During this time, water is collected as a byproduct in the 
distillation receiver. The reaction mixture is then poured into a pan and 
allowed to cool to room temperature, about 25.degree. C. 
The inks of the present invention can be prepared by any suitable method. 
For example, the inks can be prepared by gently stirring or shaking the 
individual components, such as melt mixing the vehicle with a colorant at 
a temperature of from about 90.degree. C. to about 130.degree. C., 
followed by cooling to about 25.degree. C. 
The inks of the present invention are particularly suitable for use in 
acoustic ink jet printing processes. In acoustic ink jet printing, 
reference a number of the copending applications and patents recited here, 
the disclosures of which have been totally incorporated herein by 
reference, an acoustic beam exerts a radiation pressure against objects 
upon which it impinges. Thus, when an acoustic beam impinges on a free 
surface of the ink of a pool of liquid from beneath, the radiation 
pressure which it exerts against the surface of the pool may reach a 
sufficiently high level to release individual droplets of liquid from the 
pool, despite the restraining force of surface tension. Focusing the beam 
on or near the surface of the pool intensifies the radiation pressure it 
exerts for a given amount of input power, reference, for example, IBM 
Technical Disclosure Bulletin, Vol. 16, No. 4, September 1973, pages 1168 
to 1170, the disclosure of which is totally incorporated herein by 
reference. Acoustic ink printers typically comprise one or more acoustic 
radiators for illuminating the free surface of a pool of liquid ink with 
respective acoustic beams. Each of these beams usually is brought to focus 
at or near the surface of the reservoir (i.e., the liquid/air interface). 
Furthermore, printing conventionally is performed by independently 
modulating the excitation of the acoustic radiators in accordance with the 
input data samples for the image that is to be printed. This modulation 
enables the radiation pressure, which each of the beams exerts against the 
free ink surface, to make brief, controlled excursions to a sufficiently 
high pressure level for overcoming the restraining force of surface 
tension. That, in turn, causes individual droplets of ink to be ejected 
from the free ink surface on demand at an adequate velocity to cause them 
to deposit in an image configuration on a nearby recording medium. The 
acoustic beam may be intensity modulated or focused/defocused to control 
the ejection timing, or an external source may be used to extract droplets 
from the acoustically excited liquid on the surface of the pool on demand. 
Regardless of the timing mechanism employed, the size of the ejected 
droplets is determined by the waist diameter of the focused acoustic beam. 
Acoustic ink printing is attractive because it does not require the 
nozzles or the small ejection orifices which have caused many of the 
reliability and pixel placement accuracy problems that conventional drop 
on demand and continuous stream ink jet printers have suffered. 
The size of the ejection orifice is a critical design parameter of an ink 
jet because it determines the size of the droplets of ink that the jet 
ejects. As a result, the size of the ejection orifice cannot be increased 
without sacrificing resolution. Acoustic printing has increased intrinsic 
reliability since usually there are no nozzles to clog. Furthermore, small 
ejection orifices are avoided, so acoustic printing can be performed with 
a greater variety of inks than conventional ink jet printing, including 
inks having higher viscosities and inks containing pigments and other 
particulate components. Acoustic ink printers embodying printheads 
comprising acoustically illuminated spherical focusing lenses can print 
precisely positioned pixels (picture elements) at resolutions which are 
sufficient for high quality printing of relatively complex images. It has 
also been determined that the size of the individual pixels printed by 
such a printer can be varied over a significant range during operation, 
thereby accommodating, for example, the printing of variably shaded 
images. Furthermore, the known droplet ejector technology can be adapted 
to a variety of printhead configurations, including (1) single ejector 
embodiments for raster scan printing, (2) matrix configured ejector arrays 
for matrix printing, and (3) several different types of pagewidth ejector 
arrays ranging from (i) single row, sparse arrays for hybrid forms of 
parallel/serial printing to (ii) multiple row staggered arrays with 
individual ejectors for each of the pixel positions or addresses within a 
pagewidth image field (i.e., single ejector/pixel/line) for ordinary line 
printing. Inks suitable for acoustic ink jet printing typically are liquid 
at ambient temperatures (i.e., about 25.degree. C.), however, in other 
embodiments the ink is in a solid state at ambient temperatures and 
provision is made for liquefying the ink by heating or any other suitable 
method prior to introduction of the ink into the printhead. Images of two 
or more colors can be generated by several methods, including by processes 
wherein a single printhead launches acoustic waves into pools of different 
colored inks. Further information regarding acoustic ink jet printing 
apparatus and processes is disclosed in, for example, U.S. Pat. No. 
4,308,547, U.S. Pat. No. 4,697,195, U.S. Pat. No. 5,028,937, U.S. Pat. No. 
5,041,849, U.S. Pat. No. 4,751,529, U.S. Pat. No. 4,751,530, U.S. Pat. No. 
4,751,534, U.S. Pat. No. 4,801,953, and U.S. Pat. No. 4,797,693, the 
disclosures of each of which are totally incorporated herein by reference. 
The use of focused acoustic beams to eject droplets of controlled diameter 
and velocity from a free-liquid surface is also described in J. Appl. 
Phys., vol. 65, no. 9 (1 May 1989) and references therein, the disclosure 
of which is totally incorporated herein by reference. 
Other modifications of the present invention may occur to those of ordinary 
skill in the art subsequent to a review of the present application, and 
these modifications, including equivalents thereof, are intended to be 
included within the scope of the present invention.

EXAMPLE I 
Synthesis of the reversible crosslinked vehicle from JEFFAMINE.TM. EDR-192, 
a poly(ethylylene glycol) bis(2-aminopropyl ether) of a molecular weight 
of 192 grams per mole, and phthalic anhydride was accomplished as follows: 
A 300 milliliter Parr reactor equipped with a mechanical stirrer and a 
distillation apparatus was charged with 94 grams of JEFFAMINE.TM. 192 
obtained from Huntsman Chemical Company, and 74 grams of phthalic 
anhydride. The mixture was then heated to 100.degree. C. over a 2 hour 
period, followed by increasing the temperature slowly to 150.degree. C. 
and then to 175.degree. C. over a four hour period. The pressure was then 
reduced from atmospheric pressure to about 1 millimeter Hg, and these 
conditions were maintained for an additional one hour, wherein the total 
amount of water collected in the distillation receiver during the process 
was measured to be about 5 milliliters. The pressure was then increased to 
atmospheric pressure and the product, a viscous liquid, comprised of a 
mixture of N'-ethyloxyethyloxy ethyloxyethylamine phthalimide and 
crosslinked poly(N'-(ethyloxyethyloxy ethyloxy)ethylamine) phthalamide, 
was poured into a metal container and left undisturbed to cool down to 
room temperature (about 25.degree. C. throughout the Examples). 
EXAMPLE II 
Synthesis of the reversible crosslinked vehicle from JEFFAMINE.TM. D-230, a 
poly(propylene glycol) bis(2-aminopropyl ether) of molecular weight of 230 
grams per mole, and phthalic anhydride was accomplished as follows: 
A 300 milliliter Parr reactor equipped with a mechanical stirrer and a 
distillation apparatus was charged with 115 grams of JEFFAMINE.TM. D-230 
obtained from Huntsman Chemical Company, and 74 grams of phthalic 
anhydride. The mixture was then heated to 100.degree. C. over a 2 hour 
period, followed by increasing the temperature slowly to 150.degree. C. 
and then to 175.degree. C. over a four hour period. The pressure was then 
reduced from atmospheric pressure to about 1 millimeter Hg, and these 
conditions were maintained for an additional one hour, wherein the total 
amount of water collected in the distillation receiver during the process 
was measured to be about 8 milliliters. The pressure was then increased to 
atmospheric pressure and the product, a viscous liquid comprised of a 
mixture of N'-(polypropyloxy)propylamine phthalimide crosslinked 
poly(N'-(polypropyloxyl)propylamine) phthalamide, was poured into a metal 
container and left undisturbed to cool down to room temperature. 
EXAMPLE III 
Synthesis of the reversible crosslinked vehicle obtained from JEFFAMINE.TM. 
D-400, a poly(propylene glycol) bis(2-aminopropyl ether) of a molecular 
weight of 400 grams per mole, and phthalic anhydride was accomplished as 
follows: 
A 300 milliliter Parr reactor equipped with a mechanical stirrer and a 
distillation apparatus was charged with 100 grams of JEFFAMINE.TM. D-400 
obtained from Huntsman Chemical Company, and 37 grams of phthalic 
anhydride. The mixture was then heated to 100.degree. C. over a 2 hour 
period, followed by increasing the temperature slowly to 150.degree. C. 
and then to 175.degree. C. over a four hour period. The pressure was then 
reduced from atmospheric pressure to about 1 millimeter Hg, and these 
conditions were maintained for an additional hour, wherein the total 
amount of water collected in the distillation receiver during the process 
was measured to be about 4 milliliters. The pressure was then increased to 
atmospheric pressure and the product, a viscous liquid comprised of a 
mixture of N'-(polypropyloxy)propylamine phthalimide and crosslinked 
poly(N'-(polypropyloxyl)propylamine) phthalamide, was poured into a metal 
container and left undisturbed to cool down to room temperature. 
EXAMPLE IV 
Synthesis of the reversible crosslinked vehicle obtained from JEFFAMINE.TM. 
T-403, a poly(propylene glycol) tris(2-aminopropyl ether) of molecular 
weight of 403 grams per mole, and phthalic anhydride was accomplished as 
follows: 
A 300 milliliter Parr reactor equipped with a mechanical stirrer and a 
distillation apparatus was charged with 100.8 grams of JEFFAMINE.TM. T-403 
obtained from Huntsman Chemical Company, and 37 grams of phthalic 
anhydride obtained from Fisher Chemical Company. The mixture was then 
heated to 100.degree. C. over a 2 hour period, followed by increasing the 
temperature slowly to 150.degree. C. and then to 175.degree. C. over a 
four hour period. The pressure was then reduced from atmospheric pressure 
to about 1 millimeter Hg, and these conditions were maintained for an 
additional one hour, wherein the total amount of water collected in the 
distillation receiver during the process was measured to be about 4 
milliliters. The pressure was then increased to atmospheric pressure and 
the product, a viscous liquid comprised of a mixture of 
N'-(polypropyloxy)propylamine phthalimide and crosslinked 
poly(N'-(polypropyloxyl)propylamine) phthalamide, was poured into a metal 
container and left undisturbed to cool down to room temperature. 
EXAMPLE V 
Synthesis of the reversible crosslinked vehicle generated from 
1,12-dodecanediamine and phthalic anhydride was accomplished as follows: 
A 300 milliliter Parr reactor equipped with a mechanical stirrer and a 
distillation apparatus was charged with 66.8 grams of 1,12-dodecanediamine 
obtained from E. I. DuPont and 49.4 grams of phthalic. The mixture was 
then heated to 100.degree. C. over a 2 hour period, followed by increasing 
the temperature slowly to 150.degree. C. and then to 175.degree. C. over a 
four hour period. The pressure was then reduced from atmospheric pressure 
to about 1 millimeter Hg, and these conditions were maintained for an 
additional hour, wherein the total amount of water collected in the 
distillation receiver during the process was measured to be about 5 
milliliters. The pressure was then increased to atmospheric pressure and 
the product comprised of a mixture of N'-(12-aminododecyl) phthalimide and 
crosslinked poly(N'-12-aminododecyl) phthalamide, was poured into a metal 
container and left undisturbed to cool down to room temperature. 
EXAMPLE VI 
Synthesis of the reversible crosslinked vehicle polymer generated from 
1,12-dodecanediamine and dodecenyl succinic anhydride was accomplished as 
follows: 
A 300 milliliter Parr reactor equipped with a mechanical stirrer and a 
distillation apparatus was charged with 66.8 grams of 1,12-dodecanediamine 
obtained from E. I. DuPont, and 88.7 grams of dodecenyl succinic anhydride 
obtained from Lonza. The mixture was then heated to 100.degree. C. over a 
2 hour period, followed by increasing the temperature slowly to 
150.degree. C. and then to 175.degree. C. over a four hour period. The 
pressure was then reduced from atmospheric pressure to about 1 millimeter 
Hg, and these conditions were maintained for an additional hour, wherein 
the total amount of water collected in the distillation receiver during 
the process was measured to be about 5 milliliters. The pressure was then 
increased to atmospheric pressure and the product comprised of a mixture 
of N'-(12-aminododecyl) 2-stearylsuccinimide crosslinked 
poly(N'-12-aminododecyl)2-stearylsuccinamide was poured into a metal 
container and left undisturbed to cool down to room temperature. 
Viscosity Measurements 
The rheological characterization, and more specifically, the viscosity of 
the above prepared vehicles was performed using the Carri-Med CSL-100 
controlled stress rheometer using a 4 centimeter, 2 degree cone and plate 
geometry. 
______________________________________ 
Example Viscosity (cp) at 160.degree. C. 
______________________________________ 
I 13 
II 13 
III 8 
IV 10 
V 15 
______________________________________ 
The vehicles were melt mixed with 5 percent by weight of Neopan Blue dye to 
form inks, and each ink was incorporated into an acoustic ink jet printing 
test fixture utilizing the ejection mechanism disclosed in J. Appl. Phys. 
65(9), 1 May 1989, and references therein, the disclosure of which are 
totally incorporated herein by reference. A jetting frequency of 160 MHz 
was used to generate drops of about 2 picoliters, up to 12 drops per pixel 
at 600 spi. The images formed exhibited excellent quality, high 
definition, sharp edges, and waterfastness. 
Other modifications of the present invention may occur to those of ordinary 
skill in the art based upon a review of the present application and these 
modifications, including equivalents thereof, are intended to be included 
within the scope of the present invention and the claims.