U.S. patent application number 12/360459 was filed with the patent office on 2010-07-29 for pigmented phase change inks with dispersant and synergist.
This patent application is currently assigned to XEROX CORPORATION. Invention is credited to C. Geoffrey ALLEN, Marcel P. BRETON, James D. MAYO, Caroline M. TUREK, Raymond W. WONG.
Application Number | 20100190904 12/360459 |
Document ID | / |
Family ID | 42102519 |
Filed Date | 2010-07-29 |
United States Patent
Application |
20100190904 |
Kind Code |
A1 |
WONG; Raymond W. ; et
al. |
July 29, 2010 |
PIGMENTED PHASE CHANGE INKS WITH DISPERSANT AND SYNERGIST
Abstract
A phase change ink composition includes an ink vehicle and at
least one pigment, wherein the ink composition is substantially
solid at room temperature and includes at least one dispersant for
the at least pigment and at least one synergist.
Inventors: |
WONG; Raymond W.;
(Mississauga, CA) ; MAYO; James D.; (Mississauga,
CA) ; ALLEN; C. Geoffrey; (Waterdown, CA) ;
BRETON; Marcel P.; (Mississauga, CA) ; TUREK;
Caroline M.; (Hamilton, CA) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC.
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
XEROX CORPORATION
Norwalk
CT
|
Family ID: |
42102519 |
Appl. No.: |
12/360459 |
Filed: |
January 27, 2009 |
Current U.S.
Class: |
524/275 ;
106/31.6; 106/31.61; 106/31.65; 524/585 |
Current CPC
Class: |
C09D 11/34 20130101;
C09D 11/322 20130101 |
Class at
Publication: |
524/275 ;
106/31.6; 106/31.65; 106/31.61; 524/585 |
International
Class: |
C09D 11/10 20060101
C09D011/10; C09D 11/12 20060101 C09D011/12 |
Claims
1. A phase change ink composition comprising an ink vehicle and at
least one pigment, wherein the ink composition is substantially
solid at room temperature and includes (1) at least one dispersant
soluble in the ink vehicle and (2) at least one solid synergist
insoluble in the ink vehicle, and wherein the average particle size
of the ink composition, when stored at 120.degree. C. for 30 days,
increases by less than 20% from an average particle size of the ink
composition when freshly made.
2. The phase change ink composition according to claim 1, wherein
the average particle size of the ink composition, when stored at
120.degree. C. for 30 days, increases by less than 15% from an
average particle size of the ink composition when freshly made.
3. The phase change ink composition according to claim 1, wherein
the average particle size of the freshly made ink composition is
from about 150 nm to about 300 nm.
4. The phase change ink composition according to claim 1, wherein
the at least one solid synergist includes a functional group that
adsorbs to the surface of the at least one pigment.
5. The phase change ink composition according to claim 4, wherein
the functional group includes amines, amides, esters, sulfonates,
carboxylic acids, hydroxyl groups, anhydrides, urethanes, ureas,
quaternary ammonium salts and combinations thereof.
6. The phase change ink composition according to claim 4, wherein
the at least one dispersant comprises a portion interactive with
the at least one solid synergist and a portion soluble in the ink
vehicle.
7. The phase change ink composition according to claim 6, wherein
the ink vehicle includes at least one wax, and wherein a portion of
the at least one dispersant is soluble in the at least one wax.
8. The phase change ink composition according to claim 7, wherein
the at least one solid synergist is insoluble in the at least one
wax.
9. The phase change ink composition according to claim 1, wherein
the ink vehicle comprises at least one wax and at least one amide
resin.
10. The phase change ink composition according to claim 9, wherein
the at least one amide resin has a formula of: ##STR00007## wherein
R.sub.1 is (i) an alkylene group having from about 3 carbon atoms
to about 200 carbon atoms, (ii) an arylene group having from about
6 carbon atoms to about 200 carbon atoms, (iii) an arylalkylene
group having from about 7 carbon atoms to about 200 carbon atoms,
or (iv) an alkylarylene group having from about 7 carbon atoms to
about 200 carbon atoms, R.sub.a, R.sub.b and R.sub.c are each
independently (i) a hydrogen atom, (ii) an alkyl group having from
about 1 carbon atoms to about 200 carbon atoms, (iii) an aryl group
having from about 6 carbon atoms to about 200 carbon atoms, (iv) an
arylalkyl group having from about 6 carbon atoms to about 200
carbon atoms, or (v) an alkylaryl group having from about 6 carbon
atoms to about 200 carbon atoms, and R.sub.d, R.sub.e and R.sub.f
are each independently (i) an alkyl group having from about 1
carbon atoms to about 200 carbon atoms, (ii) an aryl group having
from about 6 carbon atoms to about 200 carbon atoms, (iii) an
arylalkyl group having from about 6 carbon atoms to about 200
carbon atoms, or (iv) an alkylaryl group having from about 6 carbon
atoms to about 200 carbon atoms.
11. The phase change ink composition according to claim 9, wherein
the at least one wax is a polyethylene wax.
12. The phase change ink composition according to claim 6, wherein
the portion of the dispersant interactive with the at least one
solid synergist is at least one functional group of amines, amides,
esters, sulfonates, carboxylic acids, hydroxyl groups, anhydrides,
urethanes, ureas, salt groups or combinations thereof.
13. The phase change ink composition according to claim 6, wherein
the portion of the dispersant soluble in the ink vehicle comprises
linear or branched alkyl or alkoxyl groups having from about 1 to
about 50 carbon atoms.
14. A phase change ink composition comprising an ink vehicle and at
least one pigment, wherein the ink composition includes at least
one dispersant for the at least one pigment in an amount of from
about 0.1% by weight to about 1.5% by weight of the ink
composition, the at least one dispersant being soluble in the ink
vehicle, and at least one solid synergist that is insoluble in the
ink vehicle and is present in an amount of from about 0.1% by
weight to about 5% by weight of the pigment in the ink
composition.
15. The phase change ink composition according to claim 14, wherein
the ink vehicle includes a wax, the at least one solid synergist
being insoluble in the wax and including a functional group that
adsorbs to the surface of the at least one pigment.
16. The phase change ink composition according to claim 15, wherein
the functional group includes amines, amides, esters, sulfonates,
carboxylic acids, hydroxyl groups, anhydrides, urethanes, ureas,
quaternary ammonium salts or combinations thereof.
17. The phase change ink composition according to claim 15, wherein
the at least one dispersant comprises a portion interactive with
the at least one solid synergist and a portion soluble in the
wax.
18. The phase change ink composition according to claim 17, wherein
the portion of the dispersant interactive with the at least one
solid synergist is at least one functional group of amines, amides,
esters, sulfonates, carboxylic acids, hydroxyl groups, anhydrides,
urethanes, ureas, salt groups or combinations thereof, and wherein
the portion of the dispersant soluble in the ink vehicle comprises
linear or branched alkyl or alkoxyl groups having from about 1 to
about 50 carbon atoms.
19. The phase change ink composition according to claim 15, wherein
the ink vehicle further comprises at least one amide resin and at
least one urethane resin.
20. A phase change ink composition comprising an ink vehicle and at
least one pigment, the ink vehicle comprising at least one wax and
at least one amide resin, wherein the ink composition includes at
least one dispersant for the at least one pigment and at least one
solid synergist, the at least one solid synergist including a
functional group that adsorbs to the surface of the at least one
pigment and being insoluble in the wax, the at least one dispersant
comprising a portion interactive with the at least one solid
synergist and a portion soluble in the wax.
Description
BACKGROUND
[0001] Described herein are phase change ink compositions
comprising an ink vehicle and at least one pigment, wherein the ink
composition is substantially solid at room temperature and includes
at least one dispersant and at least one synergist. The dispersant
and synergist allow the pigment to be well dispersed in the solid
phase change ink composition without adversely affecting the
hardness of the ink. The phase change inks are suitable for ink jet
printing processes
[0002] Advantages achieved by the phase change inks herein include
that the use of at least one dispersant and at least one synergist
results in very stable inks, as determined by the measurement of
particle size after subjecting the inks to high temperatures, for
example 100.degree. C., for extended periods of time, for example 1
week. Furthermore, the amount of dispersant, in particular
dispersants that are liquid or paste-like at room temperature,
required to stabilize the pigment in the ink can be reduced without
sacrificing ink stability, thereby also achieving a reduction in
the tackiness of the ink during processing and on image prints from
the subsequent printed ink.
REFERENCES
[0003] Ink jet printing processes may employ inks that are solid at
room temperature, for example from about 20.degree. C. to about
27.degree. C., and that are liquid at elevated jetting
temperatures, for example of from about 60.degree. C. to about
150.degree. C. Such inks are typically referred to as hot melt inks
or phase change inks.
[0004] In ink jet printing processes employing a phase change ink,
the substantially solid ink is melted by the heater in the printing
apparatus and jetted as a liquid in a manner similar to that of
conventional liquid ink jet printing. Upon contact with the
printing substrate, which can be either an intermediate transfer
medium, such as an aluminum drum, or the receiving substrate, such
as paper or transparency material, the molten ink solidifies
rapidly, desirably solidifying at a rate enabling the colorant to
substantially remain on the surface of the substrate instead of
being carried into the substrate (for example, paper) by capillary
action, thereby enabling higher print density than is generally
obtained with liquid inks. Advantages of a phase change ink in ink
jet printing thus include little or no evaporation of the ink's
components, elimination of potential spillage of the ink during
handling, a wide range of print density and quality, minimal paper
cockle or distortion, and enablement of indefinite periods of
nonprinting without the danger of nozzle clogging, even without
capping the nozzles.
[0005] U.S. Patent Application Publication No. 2008/0098929,
incorporated herein by reference in its entirety, describes a phase
change ink having an ink vehicle, at least one colorant, at least
one triamide and at least one bis-urethane. The at least one
triamide and at least one bis-urethane can assist in dispersing
colorants, such as pigments like carbon black, in non-polar ink
vehicles.
[0006] U.S. Patent Application Publication No. 2008/0098927,
incorporated herein by reference in its entirety, describes a
pigmented phase change ink composition comprising an ink carrier, a
dispersing agent, and pigment particles. The ink can be resistant
to substantial aggregation and settling of the pigment particles in
the melt and even when exposed to freeze thaw cycles.
[0007] U.S. Pat. No. 7,407,539, incorporated herein by reference in
its entirety, describes a phase change ink comprising (a) a
colorant and (b) a phase change ink carrier, said carrier
comprising (i) a branched triamide and (ii) a polyethylene wax
having an average peak molecular weight of from about 350 to about
730, a polydispersity of from about 1.03 to about 3.0, and an
asymmetrical molecular weight distribution skewed toward the high
molecular weight end.
[0008] U.S. Pat. No. 7,293,868, incorporated herein by reference in
its entirety, describes ink compositions that include one or more
radiation curable oil soluble components and one or more thermal
solvents, as well as methods of preparing such ink compositions and
methods of using such ink compositions.
[0009] U.S. Pat. No. 6,860,930, incorporated herein by reference in
its entirety, describes a phase change ink composition comprising
(a) a colorant and (b) a carrier comprising a polyamide, wherein
the polyamide component of the carrier contains at least about 10
percent by weight of a branched triamide.
[0010] Solid inks typically employ dyes as colorants. Certain dyes
are very expensive, contributing a significant amount to the ink
cost, and may suffer from poor lightfastness, dye
migration/bleeding issues and/or poor solubility. Pigments can be
significantly less costly than dyes and offer excellent color and
thermal stability, and improved colorant migration resistance
properties.
[0011] In phase change inks, a dispersant may be used to assist in
stabilizing the dispersion of the pigment of the ink in the ink
vehicles. In order to effectively stabilize the pigment, higher
dispersant loadings have been used, for example loading amounts of
about 5% by weight or more of the ink. However, the higher loading
of the dispersant may adversely affect the hardness of the ink,
resulting in an ink with relatively soft and tacky characteristics.
Prints formed with such an ink may experience higher incidences of
sticking and transfer to a transfuse drum used during the image
formation process. While decreasing the amount of dispersant can
avoid undesirable softening of the ink, the pigment may not be
sufficiently stabilized in the ink, creating other potential
problems such as long term ink stability, which can negatively
impact jetting reliability.
[0012] What is desired is a phase change ink composition that
includes a stabilized pigmented ink system that is not soft and
tacky.
SUMMARY
[0013] These and other objects are achieved herein, where, in
embodiments, disclosed is a phase change ink composition comprising
an ink vehicle and at least one pigment, wherein the ink
composition is substantially solid at room temperature and includes
at least one dispersant and at least one synergist for the at least
one pigment, and wherein the average particle size of the ink
composition, when stored at 120.degree. C. for 30 days, increases
by less than 20% from an average particle size of the ink
composition when freshly made.
[0014] In further embodiments, described is a phase change ink
composition comprising an ink vehicle and at least one pigment,
wherein the ink composition includes at least one dispersant for
the at least one pigment in an amount of from about 0.1% by weight
to about 1.5% by weight of the ink composition, and at least one
synergist in an amount of from about 0. 1% by weight to about 5% by
weight of the pigment in the ink composition.
[0015] In still further embodiments, described is a phase change
ink composition comprising an ink vehicle and at least one pigment,
the ink vehicle comprising at least one wax and at least one amide
resin, wherein the ink composition includes at least one dispersant
for the at least one pigment and at least one synergist, the at
least one synergist including a functional group that adsorbs to
the surface of the at least one pigment and being insoluble in the
wax, the at least one dispersant comprising a portion interactive
with the at least one synergist and a portion soluble in the
wax.
Embodiments
[0016] The phase change inks herein are substantially solid at
temperatures of about 20.degree. C. to about 27.degree. C., for
example room temperature, and specifically are substantially solid
at temperatures below about 40.degree. C. However, the inks chance
phase upon heating, and are in a molten state at jetting
temperatures. Thus, the inks have a viscosity of from about 1 to
about 40 centipoise (cP), such as from about 5 to about 15 cP or
from about 8 to about 12 cP, at an elevated temperature suitable
for ink jet printing, such as temperatures of from about 50.degree.
C. to about 150.degree. C.
[0017] In this regard, the inks herein may be regarded as low
energy inks. Low energy inks are solid at a temperature below about
40.degree. C. and have a viscosity of from about 5 to about 15 cP
at a jetting temperature of from about 50.degree. C. to about
150.degree. C., such as from about 70.degree. C. to about
130.degree. C. or from about 60.degree. C. to about 130.degree. C.
The inks jet at lower temperatures, and thus require lower amounts
of energy for jetting.
[0018] Any suitable ink vehicle can be employed. Typically, phase
change inks include at least a wax based vehicle.
[0019] The wax in the vehicle may act as a phase change agent in
the ink. Specifically, the ink undergoes a phase change by being
solid at room temperature and molten at jetting temperatures. The
wax thus promotes the increase in viscosity and hardness of the ink
as it cools from the jetting temperature, for example from about
75.degree. C. to about 150.degree. C., to the substrate
temperature, which is for example from about 20.degree. C. to about
65.degree. C.
[0020] As used herein, the term wax includes, for example, natural,
modified natural, synthetic waxes and compounded waxes. Natural
waxes may be of vegetable, animal, or mineral origin. Modified
waxes are natural waxes that have been treated chemically to change
their nature and properties. Synthetic waxes are made by the
reaction or polymerization of chemicals. Compounded waxes are
mixtures of various waxes or of waxes with resins or other
compounds added thereto.
[0021] Suitable waxes can include paraffins, olefins such as
polymethylene, polyethylene and polypropylene, microcrystalline
waxes, ester waxes, fatty acids and other waxy materials, fatty
amide containing materials, sulfonamide materials, resinous
materials made from different natural sources (tall oil rosins and
rosin esters, for example), and many synthetic resins, oligomers,
polymers, and copolymers and mixtures thereof
[0022] Suitable phase change waxes include polyethylene waxes,
including hydroxyl-terminated polyethylene waxes such as mixtures
of carbon chains with the structure
CH.sub.3--(CH.sub.2).sub.nCH.sub.2OH, where there is a mixture of
chain lengths, n, where the average chain length is in the range of
about 16 to about 50, and linear low molecular weight polyethylene,
of similar average chain length. Suitable examples of such waxes
include, for example, UNILIN 350, UNILIN 425, UNILIN 550 and UNILIN
700. All of these waxes are commercially available from
Baker-Petrolite.
[0023] Examples of suitable specific ink vehicles include, for
example, ethylene/propylene copolymers, such as those available
from Baker Petrolite having the general formula
##STR00001##
wherein x is an integer of from about 1 to about 200, such as from
about 5 to about 150 or from about 12 to about 105. These materials
may have a melting point of from about 60.degree. C. to about
150.degree. C., such as from about 70.degree. C. to about
140.degree. C. or from about 80.degree. C. to about 130.degree. C.
and a number average molecular weight (Mn) of from about 100 to
about 5,000, such as from about 200 to about 4,000 or from about
400 to about 3,000. Commercial examples of such copolymers include,
for example, the POLYWAX.RTM. line of waxes from
Baker-Petrolite.
[0024] The ability of the wax to crystallize contributes to its
overall hardness, which imparts strength to the ink. The degree of
crystallization can be controlled by regulating the degree of
branching (that is, irregularity) of the wax. A high degree of
linearity of a polyethylene chain generally yields a highly
crystalline and hard material. The hardness of the ink is also
directly dependent on the molecular weight of the waxy components,
such that higher molecular weight waxes afford inks that are
relatively harder and potentially more robust.
[0025] Other suitable phase change waxes include alcohol waxes, for
example, hydrogenated castor oil, 1-octadecanol, 1,10-decanediol
and 1,12-dodecanediol. Other examples of mono functional alcohols
that can be employed as phase change waxes herein include
1-tetradecanol, 1-pentadecanol, 1-hexadecanol, 1-heptadecanol,
1-nonadecanol, 1-eicosanol, 1-tricosanol, 1-tetracosanol,
1-pentacosanol, 1-hexacosanol, 1-heptacosanol, 1-octacosanol,
1-nonacosanol, 1-tricontanol, 1-dotriacontanol, 1-tritriacontanol,
1-tetratriacontanol. Also suitable are Guerbet alcohols such as
2-tetradecyl 1-octadecanol, 2-hexadecyl 1-eicosanol, 2-octadecyl
1-docosanol, 2-nonadecyl 1-tricosanol, 2-eicosyl tetracosanol, and
mixtures thereof. Suitable diols include 1,8-octanediol,
1,9-nonanediol, 1,13-tridecanediol, 1,14-tetradecanediol,
1,15-pentadecanediol, 1,16-hexandecanediol, 1,17-heptadecanediol,
1,18-octadecanediol, 1,19-nonadecanediol, 1,20-eicosanediol,
1,22-docosanediol, 1,25-pentacosanediol, and mixtures thereof.
[0026] Other suitable phase change waxes include carboxylic acid
waxes, for example, UNICID.RTM. 350, UNICID.RTM. 425, UNICID.RTM.
550 and UNICID.RTM. 700. All of these waxes are commercially
available from Baker-Petrolite.
[0027] Examples of urethane waxes that may be used include the
reaction product of an isocyanate and an alcohol. Examples of
suitable isocyanates include monoisocyanates, diisocyanates,
triisocyanates, copolymers of a diisocyanate, copolymers of a
triisocyanate, polyisocyanates (having more than three isocyanate
functional groups), and the like, as well as mixtures thereof.
Examples of monoisocyanates include n-octadecylisocyanate,
hexadecylisocyanate; octylisocyanate; n- and t-butylisocyanate;
cyclohexyl isocyanate; adamantyl isocyanate;
ethylisocyanatoacetate; ethoxycarbonylisocyanate; phenylisocyanate;
alphamethylbenzyl isocyanate; 2-phenylcyclopropyl isocyanate;
benzylisocyanate; 2-ethylphenylisocyanate; benzoylisocyanate; meta
and para-tolylisocyanate; 2-, 3-, or 4-nitrophenylisocyanates;
2-ethoxyphenyl isocyanate; 3-methoxyphenyl isocyanate;
4-methoxyphenylisocyanate; ethyl 4-isocyanatobenzoate;
2,6-dimethylphenylisocyante; 1-naphthylisocyanate;
(naphthyl)ethylisocyantes; and the like, as well as mixtures
thereof. Examples of diisocyanates include isophorone diisocyanate
(IPDI), toluene diisocyanate (TDI);
diphenylmethane-4,4'-diisocyanate (MDI); hydrogenated
diphenylmethane-4,4'-diisocyanate; tetra-methyl xylene diisocyanate
(TMXDI); hexamethylene-1,6-diisocyanate (HDI),
naphthalene-1,5-diisocyanate; 3,3
'-dimethoxy-4,4'-biphenyldiisocyanate;
3,3'-dimethyl-4,4'-bimethyl-4,4'-biphenyldiisocyanate; phenylene
diisocyanate; 4,4'-biphenyldiisocyanate;
trimethyl-1,6-diisocyanatohexane, tetramethylene xylene
diisocyanate; 4,4'-methylenebis(2,6-diethylphenyl isocyanate);
1,12-diisocyanatododecane; 1,5-diisocyanato-2-methylpentane;
1,4-diisocyanatobutane; dimer diisocyanate and cyclohexylene
diisocyanate and its isomers; uretidione dimers of HDI; and the
like, as well as mixtures thereof Examples of triisocyanates or
their equivalents include the trimethylolpropane trimer of TDI, and
the like, isocyanurate trimers of TDI, HDI, IPDI, and the like, and
biuret trimers of TDI, HDI, IPDI, and the like, as well as mixtures
thereof. Examples of higher isocyanate functionalities include
copolymers of TDI/HDI, and the like, and MDI oligomers, as well as
mixtures thereof.
[0028] In embodiments, the wax is functionalized with one or more
curable moieties, including, for example, vinyl ethers; epoxides,
such as cycloaliphatic epoxides, aliphatic epoxides, and glycidyl
epoxides; oxetanes; (meth)acrylates, that is, acrylates and
methacrylates; and the like.
[0029] Additional examples of wax materials that may be used as the
ink vehicle are set forth in, for example, U.S. Pat. No. 6,860,930,
incorporated herein by reference in its entirety.
[0030] The ink vehicle may also include fatty amides, such as
monoamides, tetra-amides, mixtures thereof, and the like, for
example such as described in U.S. Pat. No. 6,858,070, incorporated
herein by reference in its entirety. Suitable monoamides may have a
melting point of at least about 50.degree. C., for example from
about 50.degree. C. to about 150.degree. C., although the melting
point can be above or below these temperatures. Specific examples
of suitable monoamides include, for example, primary monoamides and
secondary monoamides. Stearamide, such as KEMAMIDE S available from
Witco Chemical Company and CRODAMIDE S available from Croda,
behenamide/arachidamide, such as KEMAMIDE B available from Witco
and CRODAMIDE BR available from Croda, oleamide, such as KEMAMIDE U
available from Witco and CRODAMIDE OR available from Croda,
technical grade oleamide, such as KEMAMIDE O available from Witco,
CRODAMIDE O available from Croda, and UNISLIP 1753 available from
Uniqema, and erucamide such as KEMAMIDE E available from Witco and
CRODAMIDE ER available from Croda, are some examples of suitable
primary amides. Behenyl behenamide, such as KEMAMIDE EX666
available from Witco, stearyl stearamide, such as KEMAMIDE S-180
and KEMAMIDE EX-672 available from Witco, stearyl erucamide, such
as KEMAMIDE E-180 available from Witco and CRODAMIDE 212 available
from Croda, erucyl erucamide, such as KEMAMIDE E-221 available from
Witco, oleyl palmitamide, such as KEMAMIDE P-181 available from
Witco and CRODAMIDE 203 available from Croda, and erucyl
stearamide, such as KEMAMIDE S-221 available from Witco, are some
examples of suitable secondary amides. Additional suitable amide
materials include KEMAMIDE W40 (N,N'-ethylenebisstearamide),
KEMAMIDE P181 (oleyl palmitamide), KEMAMIDE W45
(N,N'-thylenebisstearamide), and KEMAMIDE W20
(N,N'-ethylenebisoleamide).
[0031] Additional examples of suitable ink vehicle components for
the phase change inks include rosin esters, such as glyceryl
abietate (KE-100.RTM.); polyamides; dimer acid amides; fatty acid
amides, including ARAMID C; epoxy resins, such as EPOTUF 37001,
available from Riechold Chemical Company; fluid paraffin waxes;
fluid microcrystalline waxes; Fischer-Tropsch waxes; polyvinyl
alcohol resins; polyols; cellulose esters; cellulose ethers;
polyvinyl pyridine resins; fatty acids; fatty acid esters; poly
sulfonamides, including KETJENFLEX MH and KETJENFLEX MS80; benzoate
esters, such as BENZOFLEX S552, available from Velsicol Chemical
Company; phthalate plasticizers; citrate plasticizers; maleate
plasticizers; polyvinyl pyrrolidinone copolymers; polyvinyl
pyrrolidone/polyvinyl acetate copolymers; novolac resins, such as
DUREZ 12 686, available from Occidental Chemical Company; and
natural product waxes, such as beeswax, montan wax, candelilla wax,
GILSONITE (American Gilsonite Company), and the like; mixtures of
linear primary alcohols with linear long chain amides or fatty acid
amides, such as those with from about 6 to about 24 carbon atoms,
including PARICIN 9 (propylene glycol monohydroxystearate), PARICIN
13 (glycerol monohydroxystearate), PARICIN 15 (ethylene glycol
monohydroxystearate), PARICIN 220
(N(2-hydroxyethyl)-12-hydroxystearamide), PARCIN 285
(N,N'-ethylene-bis-12-hydroxystearamide), FLEXRICIN 185
(N,N'-ethylene-bis-ricinoleamide), and the like. Further, linear
long chain sulfones with from about 4 to about 16 carbon atoms,
such as diphenyl sulfone, n-arnyl sulfone, n-propyl sulfone,
n-pentyl sulfone, n-hexyl sulfone, n-heptyl sulfone, n-octyl
sulfone, n-nonyl sulfone, n-decyl sulfone, n-undecyl sulfone,
n-dodecyl sulfone, n-tridecyl sulfone, n-tetradecyl sulfone,
n-pentadecyl sulfone, n-hexadecyl sulfone, chlorophenyl methyl
sulfone, and the like, are suitable ink vehicle materials.
[0032] The ink vehicle may comprise from about 25% to about 99.5%
by weight of the ink, for example from about 30% to about 90% or
from about 50% to about 75% by weight of the ink.
[0033] The ink may also include therein at least one amide resin.
The amide resin may act as a dispersant for the pigment(s) of the
ink. The amide resin may be a triamide or higher order amide (such
as tetraamide and the like) resin.
[0034] Suitable triamides for use herein include linear triamides,
which are molecules in which all three amide groups are contained
within a single hydrocarbon backbone. Examples of linear triamides
include those triamides having the following formulas:
##STR00002##
R can be any hydrocarbon having from about 1 to about 200, carbon
atoms, such as from about 25 to 150 carbon atoms or from about 30
to about 100 carbon atoms.
[0035] Linear triamides can farther include those wherein the three
amide groups are contained within a single hydrocarbon backbone,
even though the normal depiction of the molecule would suggest the
amide groups are on different branches. One example of such a
triamide can be expressed by the following formula:
##STR00003##
which can also be depicted as:
##STR00004##
[0036] In embodiments, the triamide may also be a branched
triamide. Examples of suitable branched triamides include those
triamides disclosed in U.S. Pat. No. 6,860,930, which is
incorporated herein in its entirety by reference. Any branched
triamide disclosed in U.S. Pat. No. 6,860,930, is suitable for use
herein. Examples of branched triamides suitable for use herein
include those having the formulas:
##STR00005##
and the like are disclosed in U.S. Pat. No. 6,860,930. In such
branched triamides, R.sub.1 and R.sub.2 may be (i) an alkylene
group (including linear, branched, saturated, unsaturated, cyclic,
substituted, and unsubstituted alkylene groups, and wherein hetero
atoms, such as oxygen, nitrogen, sulfur, silicon, phosphorus, and
the like either may or may not be present in the alkylene group),
having from about 3 carbon atoms to about 200 carbon atoms, such as
from about 15 carbon atoms to about 150 carbon atoms or from about
21 carbon atoms to about 100 carbon atoms, although the number of
carbon atoms can be outside of these ranges, (ii) an arylene group
(including unsubstituted and substituted arylene groups, and
wherein hetero atoms, such as oxygen, nitrogen, sulfur, silicon,
phosphorus, and the like either may or may not be present in the
arylene group), having from about 6 carbon atoms to about 200
carbon atoms, such as from about 10 carbon atoms to about 150
carbon atoms or from about 14 carbon atoms to about 100 carbon
atoms, although the number of carbon atoms can be outside of these
ranges, (iii) an arylalkylene group (including unsubstituted and
substituted arylalkylene groups, wherein the alkyl portion of the
arylalkylene group can be linear, branched, saturated, unsaturated,
and/or cyclic, and wherein hetero atoms, such as oxygen, nitrogen,
sulfur, silicon, phosphorus, and the like either may or may not be
present in either or both of the alkyl portion and the aryl portion
of the arylalkylene group), having from about 7 carbon atoms to
about 200 carbon atoms, such as from about 8 carbon atoms to about
150 carbon atoms or from about 9 carbon atoms to about 100 carbon
atoms, although the number of carbon atoms can be outside of these
ranges, such as benzylene or the like, or (iv) an alkylarylene
group (including unsubstituted and substituted alkylarylene groups,
wherein the alkyl portion of the alkylarylene group can be linear,
branched, saturated, unsaturated, and/or cyclic, and wherein hetero
atoms, such as oxygen, nitrogen, sulfur, silicon, phosphorus, and
the like either may or may not be present in either or both of the
alkyl portion and the aryl portion of the alkylarylene group),
having from about 7 carbon atoms to about 200 carbon atoms, such as
from about 8 carbon atoms to about 150 carbon atoms or from about 9
carbon atoms to about 100 carbon atoms, although the number of
carbon atoms can be outside of these ranges, such as tolylene or
the like. R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.g, R.sub.h,
R.sub.j, R.sub.k, R.sub.p and R.sub.q may each independently be (i)
a hydrogen atom, (ii) an alkyl group (including linear, branched,
saturated, unsaturated, cyclic, substituted, and unsubstituted
alkyl groups, and wherein hetero atoms, such as oxygen, nitrogen,
sulfur, silicon, phosphorus, and the like either may or may not be
present in the alkyl group), in embodiments from about 1 carbon
atoms to about 200 carbon atoms, such as from about 6 carbon atoms
to about 150 carbon atoms or from about 10 carbon atoms to about
100 carbon atoms, although the number of carbon atoms can be
outside of these ranges, (iii) an aryl group (including
unsubstituted and substituted aryl groups, and wherein hetero
atoms, such as oxygen, nitrogen, sulfur, silicon, phosphorus, and
the like either may or may not be present in the aryl group),
having from about 6 carbon atoms to about 200 carbon atoms, such as
from about 10 carbon atoms to about 150 carbon atoms or from about
14 carbon atoms to about 100 carbon atoms, although the number of
carbon atoms can be outside of these ranges, (iv) an arylalkyl
group (including unsubstituted and substituted arylalkyl groups,
wherein the alkyl portion of the arylalkyl group can be linear,
branched, saturated, unsaturated, and/or cyclic, and wherein hetero
atoms, such as oxygen, nitrogen, sulfur, silicon, phosphorus, and
the like either may or may not be present in either or both of the
alkyl portion and the aryl portion of the arylalkyl group), having
from about 6 carbon atoms to about 200 carbon atoms, such as from
about 7 carbon atoms to about 150 carbon atoms or from about 8
carbon atoms to about 100 carbon atoms, although the number of
carbon atoms can be outside of these ranges, such as benzyl or the
like, or (v) an alkylaryl group (including unsubstituted and
substituted alkylaryl groups, wherein the alkyl portion of the
alkylaryl group can be linear, branched, saturated, unsaturated,
and/or cyclic, and wherein hetero atoms, such as oxygen, nitrogen,
sulfur, silicon, phosphorus, and the like either may or may not be
present in either or both of the alkyl portion and the aryl portion
of the alkylaryl group), having from about 6 carbon atoms to about
200 carbon atoms, such as from about 7 carbon atoms to about 150
carbon atoms or from about 8 carbon atoms to about 100 carbon
atoms, although the number of carbon atoms can be outside of these
ranges, such as tolyl or the like. R.sub.d, R.sub.e and R.sub.f may
each independently be (i) an alkyl group as described above, (ii)
an aryl group as described above, (iii) an arylalkyl group as
described above, or (iv) an alkylaryl group as described above.
[0037] The triamide is present in the ink in amounts of from about
0.5 weight percent to about 40 weight percent, such as from about 5
weight percent to about 18 weight percent or from about 8 weight
percent to about 13 weight percent of the ink. In embodiments, the
amide resin used may be present in amounts outside of these ranges,
and may also include higher order amides, such as tetraamides,
pentaamides and the like.
[0038] One or more urethane resins may be included in the ink
composition. Suitable urethane resins are described in, for
example, U.S. Pat. No. 6,309,453, incorporated herein by reference
in its entirety.
[0039] The urethane may be present in the ink in amounts of from
about 0.5 weight percent to about 40 weight percent, such as from
about 1 weight percent to about 8 weight percent or from about 1.5
weight percent to about 5 weight percent of the ink.
[0040] The ink of embodiments may further include conventional
additives to take advantage of the known functionality associated
with such conventional additives. Examples of additives are briefly
discussed below.
[0041] Plasticizers may be included in the ink, and may include,
for example, pentaerythritol tetrabenzoate, commercially available
as BENZOFLEX S552 (Velsicol Chemical Corporation), trimethyl
titrate, commercially available as CITROFLEX 1 (Monflex Chemical
Company), N,N-dimethyl oleamide, commercially available as HALCOMID
M-18-OL (C. P. Hall Company), a benyl phthalate, commercially
available as SANTICIZER 278 (Ferro Corporation), and the like, may
be added to the ink vehicle, and may constitute from about 1 to 100
percent of the ink vehicle component of the ink. Plasticizers can
either function as the ink vehicle or can act as an agent to
provide compatibility between the ink propellant, which generally
is polar, and the ink vehicle, which generally is non-polar.
[0042] The ink may further include an optional viscosity modifier,
such as (1) 2-hydroxybenzyl alcohol, (2) 4-hydroxybenzyl alcohol,
(3) 4-nitrobenzyl alcohol, (4) 4-hydroxy-3-methoxy benzyl alcohol,
(5) 3-methoxy-4-nitrobenzyl alcohol, (6) 2-amino-5-chlorobenzyl
alcohol, (7) 2-amino-5-methylbenzyl alcohol, (8)
3-amino-2-methylbenzyl alcohol, (9) 3-amino-4-methyl benzyl
alcohol, (10) 2(2-(aminomethyl)phenylthio)benzyl alcohol, (11)
2,4,6-trimethylbenzyl alcohol, (12)
2-amino-2-methyl-1,3-propanediol, (13)
2-amino-1-phenyl-1,3-propanediol, (14)
2,2-dimethyl-1-phenyl-1,3-propanediol, (15)
2-bromo-2-nitro-1,3-propanediol, (16)
3-tert-butylamino-1,2-propanediol, (17)
1,1-diphenyl-1,2-propanediol, (18) 1,4-dibromo-2,3-butanediol, (19)
2,3-dibromo-1,4-butanediol, (20) 2,3-dibromo-2-butene-1,4-diol,
(21) 1,1,2-triphenyl-1,2-ethanediol, (22) 2-naphthalenemethanol,
(23) 2-methoxy-1-naphthalenemethanol, (24) decafluoro benzhydrol,
(25) 2-methylbenzhydrol, (26) 1-benezeethanol, (27)
4,4'-isopropylidene bis(2-(2,6-dibromo phenoxy)ethanol), (28)
2,2'-(1,4-phenylenedioxy)diethanol, (29) 2,2-his
(hydroxymethyl)-2,2',2''-nitrilotriethanol, (30)
di(trimethylolpropane), (31) 2-amino-3-phenyl-1-propanol, (32)
tricyclohexylmethanol, (33) tris(hydroxymethyl)aminomethane
succinate, (34) 4,4'-trimethylene bis(1-piperidine ethanol), (35)
N-methyl glucamine, (36) xylitol, or mixtures thereof. When
present, the viscosity modifier is present in the ink in any
effective amount, such as from about 30 percent to about 55 percent
by weight of the ink or from about 35 percent to about 50 percent
by weight of the ink.
[0043] The ink may optionally contain antioxidants to protect the
images from oxidation and also may protect the ink components from
oxidation while existing as a heated melt in the printer. Examples
of suitable antioxidants include (1) N,N'-hexamethylene
bis(3,5-di-tert-butyl-4-hydroxy hydrocinnamamide) (IRGANOX 1098,
available from Ciba-Geigy Corporation), (2)
2,2-bis(4-(2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy))ethoxyphenyl)-
propane (TOPANOL-205, available from ICI America Corporation), (3)
tris(4-tert-butyl-3-hydroxy-2,6-dimethyl benzyl)isocyanurate
(CYANOX 1790, 41, 322-4, LTDP, Aldrich D12,840-6), (4)
2,2'-ethylidene bis(4,6-di-tert-butylphenyl) fluoro phosphonite
(ETHANOX-398, available from Ethyl Corporation), (5)
tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenyl diphosphonite
(ALDRICH 46,852-5; hardness value 90), (6) pentaerythritol
tetrastearate (TCI America #PO739), (7) tributylammonium
hypophosphite (Aldrich 42,009-3), (8)
2,6-di-tert-butyl-4-methoxyphenol (Aldrich 25,106-2), (9)
2,4-di-tert-butyl-6-(4-methoxybenzyl)phenol (Aldrich 23,008-1),
(10) 4-bromo-2,6-dimethylphenol (Aldrich 34,951-8), (11)
4-bromo-3,5-didimethylphenol (Aldrich B6,420-2), (12)
4-bromo-2-nitrophenol (Aldrich 30,987-7), (13) 4-(diethyl
aminomethyl)-2,5-dimethylphenol (Aldrich 14,668-4), (14)
3-dimethylaminophenol (Aldrich D14,400-2), (15)
2-amino-4-tert-amylphenol (Aldrich 41,258-9), (16)
2,6-bis(hydroxymethyl)-p-cresol (Aldrich 22,752-8), (17)
2,2'-methylenediphenol (Aldrich B4,680-8), (18)
5-(diethylamino)-2-nitrosophenol (Aldrich 26,951-4), (19)
2,6-dichloro-4-fluorophenol (Aldrich 28,435-1), (20) 2,6-dibromo
fluoro phenol (Aldrich 26,003-7), (21) .alpha.-trifluoro-o-creso-1
(Aldrich 21,979-7), (22) 2-bromo-4-fluorophenol (Aldrich 30,246-5),
(23) 4-fluorophenol (Aldrich F1, 320-7), (24)
4-chlorophenyl-2-chloro-1,1,2-tri-fluoroethyl sulfone (Aldrich
13,823-1), (25) 3,4-difluoro phenylacetic acid (Aldrich 29,043-2),
(26) 3-fluorophenylacetic acid (Aldrich 24,804-5), (27)
3,5-difluoro phenylacetic acid (Aldrich 29,044-0), (28)
2-fluorophenylacetic acid (Aldrich 20,894-9), (29) 2,5-bis
(trifluoromethyl)benzoic acid (Aldrich 32,527-9), (30)
ethyl-2-(4-(4-(trifluoromethyl) phenoxy) phenoxy) propionate
(Aldrich 25,074-0), (31) tetrakis (2,4-di-tert-butyl
phenyl)-4,4'-biphenyl diphosphonite (Aldrich 46,852-5), (32)
4-tert-amyl phenol (Aldrich 15,384-2), (33)
3-(2H-benzotriazol-2-yl)-4-hydroxy phenethylalcohol (Aldrich
43,071-4), NAUGARD 76, NAUGARD 445, NAUGARD 512, and NAUGARD 524
(manufactured by Uniroyal Chemical Company), and the like, as well
as mixtures thereof The antioxidant, when present, may be present
in the ink in any desired or effective amount, such as from about
0.25 percent to about 10 percent by weight of the ink or from about
1 percent to about 5 percent by weight of the ink.
[0044] The ink can also optionally contain a UV absorber. The
optional UV absorbers primarily protect the generated images from
UV degradation. Specific examples of suitable UV absorbers include
(1) 2-bromo-2',4-dimethoxyacetophenone (Aldrich 19,948-6), (2)
2-bromo-2,5'-dimethoxyacetophenone (Aldrich 10,458-2), (3)
2-bromo-3'-nitroacetophenone (Aldrich 34,421-4), (4)
2-bromo-4'-nitroacetophenone (Aldrich 24,561-5), (5)
3',5'-diacetoxyacetophenone (Aldrich 11,738-2), (6)
2-phenylsulfonyl acetophenone (Aldrich 34,150-3), (7)
3'-aminoacetophenone (Aldrich 13,935-1), (8) 4'-aminoacetophenone
(Aldrich A3,800-2), (9) 1H-benzotriazole-1-acetonitrile (Aldrich
46,752-9), (10) 2-(2H-benzotriazol-2yl)-4,6-di-tert-pentylphenol
(Aldrich 42,274-6), (11)
1,1-(1,2-ethane-diyl)bis(3,3,5,5-tetramethylpiperazinone)
(commercially available from Goodrich Chemicals), (12)
2,2,4-trimethyl-1,2-hydroquinoline (commercially available from
Mobay Chemical), (13) 2-(4-benzoyl-3-hydroxy phenoxy)ethylacrylate,
(14) 2-dodecyl-N-(1,2,2,6,6-pentamethyl-4-piperidinyl) succinimide
(commercially available from Aldrich Chemical Co., Milwaukee,
Wis.), (15)
2,2,6,6-tetramethyl-4-piperidinyl/.beta.-tetramethyl-3,9-(2,4,8,10-tetrao-
xo spiro(5,5)-undecane) diethyl-1,2,3,4-butane tetracarboxylate
(commercially available from Fairmount), (16)
N-(p-ethoxycarbonylphenyl)-N'-ethyl-N'-phenylformadine
(commercially available from Givaudan), (17)
6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline (commercially
available from Monsanto Chemicals), (18)
2,4,6-tris-(N-1,4-dimethylpentyl-4-phenylenediamino)-1,3,5-triazine
(commercially available from Uniroyal), (19)
2-dodecyl-N-(2,2,6,6-tetramethyl-4-piperidinyl)succinimide
(commercially available from Aldrich Chemical Co.), (20)
N-(1-acetyl-2,2,6,6-tetramethyl-4-piperidinyl)-2-dodecyl
succinimide (commercially available from Aldrich Chemical Co.),
(21)
(1,2,2,6,6-pentamethyl-4-piperidinyl/.beta.-tetramethyl-3,9-(2,4,8,10-tet-
ra oxo-spiro-(5,5)undecane)diethyl)-1,2,3,4-butane tetracarboxylate
(commercially available from Fairmount), (22)
(2,2,6,6-tetramethyl-4-piperidinyl)-1,2,3,4-butane tetracarboxylate
(commercially available from Fairmount), (23) nickel dibutyl dithio
carbamate (commercially available as UV-Chek AM-105 from Ferro),
(24) 2-amino-2',5-dichlorobenzophenone (Aldrich 10,515-5), (25)
2'-amino-4',5'-dimethoxyacetophenone (Aldrich 32,922-3), (26)
2-benzyl-2-(dimethylamino)-4'-morpholino butyrophenone (Aldrich
40,564-7), (27) 4'-benzyloxy-2'-hydroxy-3'-methylacetophenone
(Aldrich 29,884-0), (28) 4,4'-bis(diethylamino)benzophenone
(Aldrich 16,032-6), (29) 5-chloro-2-hydroxy benzophenone (Aldrich
C4,470-2), (30) 4'-piperazinoacetophenone (Aldrich 13,646-8), (31)
4'-piperidinoacetophenone (Aldrich 11,972-5), (32)
2-amino-5-chlorobenzophenone (Aldrich A4,556-4), (33)
3,6-bis(2-methyl-2-morpholinopropionyl)-9-octylcarbazole (Aldrich
46,073-7), and the like, as well as mixtures thereof.
[0045] When present, the optional additives may each, or in
combination, be present in the ink in any desired or effective
amount, such as from about 1 percent to about 10 percent by weight
of the ink or from about 3 percent to about 5 percent by weight of
the ink.
[0046] The inks disclosed herein may contain any suitable
pigment(s) as the at least one pigment. Examples of suitable
pigments include, for example, PALIOGEN Violet 5100 (commercially
available from BASF); PALIOGEN Violet 5890 (commercially available
from BASF); HELIOGEN Green L8730 (commercially available from
BASF); LITHOL Scarlet D3700 (commercially available from BASF);
SUNFAST Blue 15:4 (commercially available from Sun Chemical);
HOSTAPERM Blue B2G-D (commercially available from Clariant);
HOSTAPERM Blue B4G (commercially available from Clariant);
Permanent Red P-F7RK; HOSTAPERM Violet BL (commercially available
from Clariant); LITHOL Scarlet 4440 (commercially available from
BASF); Bon Red C (commercially available from Dominion Color
Company); ORACET Pink RF (commercially available from Ciba);
PALIOGEN Red 3871 K (commercially available from BASF); SUNFAST
Blue 15:3 (commercially available from Sun Chemical); PALIOGEN Red
3340 (commercially available from BASF); SUNFAST Carbazole Violet
23 (commercially available from Sun Chemical); LITHOL Fast Scarlet
L4300 (commercially available from BASF); SUNBRITE Yellow 17
(commercially available from Sun Chemical); HELIOGEN Blue L6900,
L7020 (commercially available from BASE); SUNBRITE Yellow 74
(commercially available from Sun Chemical); SPECTRA PAC C Orange 16
(commercially available from Sun Chemical); HELIOGEN Blue K6902,
K6910 (commercially available from BASF); SUNFAST Magenta 122
(commercially available from Sun Chemical); HELIOGEN Blue D6840,
D7080 (commercially available from BASE); Sudan Blue OS
(commercially available from BASF); NEOPEN Blue FF4012
(commercially available from BASF); PV Fast Blue B2GO1
(commercially available from Clariant); IRGALITE Blue BCA
(commercially available from Ciba); PALIOGEN Blue 6470
(commercially available from BASF); Sudan Orange G (commercially
available from Aldrich), Sudan Orange 220 (commercially available
from BASF); PALIOGEN Orange 3040 (BASE); PALIOGEN Yellow 152, 1560
(commercially available from BASF); LITHOL Fast Yellow 0991 K
(commercially available from BASF); PALIOTOL Yellow 1840
(commercially available from BASF); NOVOPERM Yellow FGL
(commercially available from Clariant); Ink Jet Yellow 4G VP2532
(commercially available from Clariant); Toner Yellow HG
(commercially available from Clariant); Lumogen Yellow D0790
(commercially available from BASF); Suco-Yellow L1250 (commercially
available from BASF); Suco-Yellow D1355 (commercially available
from BASF); Suco Fast Yellow D1 355, D1 351 (commercially available
from BASE); HOSTAPERM Pink E 02 (commercially available from
Clariant); Hansa Brilliant Yellow 5GX03 (commercially available
from Clariant); Permanent Yellow GRL 02 (commercially available
from Clariant); Permanent Rubine L6B 05 (commercially available
from Clariant); FANAL Pink D4830 (commercially available from
BASF); CINQUASIA Magenta (commercially available from DU PONT);
PALIOGEN Black L0084 (commercially available from BASE); Pigment
Black K801 (commercially available from BASF); and carbon blacks
such as REGAL 330.TM. (commercially available from Cabot), Nipex
150 (commercially available from Degussa) Carbon Black 5250 and
Carbon Black 5750 (commercially available from Columbia Chemical),
and the like, as well as mixtures thereof.
[0047] In embodiments, the pigment may comprise from about 0.5
weight percent to about 40 weight percent of the ink, such as from
about 1 weight percent to about 8 weight percent or from about 1.5
weight percent to about 6 weight percent of the ink. Pigments
suitable for use herein include particles having an average
particle size of from about 15 nm to about 200 nm, such as from
about 15 nm to about 100 nm or from about 15 nm to about 50 nm.
[0048] There are several challenges in incorporating a pigment into
a solid phase change ink composition. Typical ink compositions have
many relatively non-polar components that can hinder pigment
stabilization. At the same time, organic pigments can be
anisotropic and have lower polarity that can make it difficult to
stabilize the pigment particles in the ink. The low viscosity and
high temperatures in use require a dispersant that is sufficiently
anchored (such as adsorbed, covalently or ionically attached, or
grafted) to the pigment particle surface such that at least a
portion of the dispersant is compatible with the low polarity
vehicle.
[0049] In general, pigment particles in a liquid based medium will
tend to flocculate unless a suitable stabilization mechanism is
employed. In non-aqueous systems, this can be achieved by adsorbing
onto the pigment particle surface a molecule that is entirely or
partially soluble in the ink medium, which prevents, or at least
hinders, pigment particles from approaching each other too closely
such that they interact and flocculate. In order to achieve good
thermal stability of the ink dispersion, the dispersant must be
strongly associated to the pigment surface, such that it does not
desorb from the pigment surface upon aging at elevated
temperatures. Addition of a suitable synergist assists in
strengthening the pigment/dispersant interaction.
[0050] The synergist contains functional groups capable of
anchoring, or adsorbing, to the pigment particle surface. The
functional groups may be polar groups. The synergist may be
insoluble in a substantial portion of the ink vehicle, although it
may be soluble in a portion of the ink vehicle.
[0051] Examples of suitable functional groups that associate the
synergist to the pigment particles include such functional groups
as amines, amides, esters, sulfonates, carboxylic acids, hydroxyl
groups, anhydrides, urethanes, ureas and salt groups such as
quaternary ammonium salts, combinations thereof and the like. The
groups anchor the synergist to the pigment particles such that the
synergist is, for example, adsorbed, attached to or grafted to the
pigment particle. The groups can suitably anchor or adsorb to the
pigment particle in any suitable manner, such as hydrogen bonding,
covalent or ionic bonding, acid-base reaction, Van der Waals
interactions, and the like.
[0052] Specific examples of synergists suitable for use herein
include, but are not limited to, for example, SOLSPERSE.RTM. 5000
from Lubrizol (a copper phthalocyanine derivatives, for example
desirably used with blue, green or black pigments, SOLSPERSE.RTM.
12000 from Lubrizol, for example desirably used with blue, green or
black pigments, SOLSPERSE.RTM. 22000 from Lubrizol for yellow,
orange or red pigments, EFKA.RTM. 6745 from Ciba-Geigy desirably
used for blue or black pigments and EFKA.RTM. 6750 from Ciba-Geigy
desirably used for yellow, orange or red pigments.
[0053] In embodiments, the ink composition includes at least one
synergist in an amount of from about 0.1% by weight to about 50% by
weight of the pigment in the ink composition, for example from
about 0.15% by weight to about 10% by weight of the pigment in the
ink composition or from about 0.5 to about 5% by weight of the
pigment in the ink composition. An adequate amount of synergist is
sufficient to permit the amount of dispersant required to stabilize
the pigment in the ink to be reduced compared to the scenario where
no synergist is present in the ink, for example to decreased
amounts of about 10 to about 90% by weight of the dispersant
without a synergist, such as from about 30 to about 80% by weight
of the dispersant without a synergist, or such as from about 60 to
about 75% by weight of the dispersant without a synergist. The
amount of dispersant in the ink composition is not particularly
limited, and may be, for example, from about 0. 1% by weight to
about 50% by weight of the pigment in the ink composition. The
amount may be low in embodiments, such as from about 0.1% by weight
to about 1.5% by weight of the ink composition, with the use of at
least one synergist.
[0054] As above, the amount of dispersant in the ink composition
may be reduced as a result of the use of the synergist. This can be
particularly advantageous in cases in which the dispersant is
tacky, because reducing the amount of tacky dispersant reduces the
tackiness of the overall ink, which can result in less tackiness on
an intermediate transfer member or image receiving surface. The
reduced amount of dispersant, however, does not adversely affect
the stability of the pigment(s) in the ink composition due to the
use of the synergist.
[0055] The effect of reducing the amount of dispersant yet
retaining the stability of the ink via addition of a synergist can
be expressed in terms of particle size measurements with aging. In
this regard, particle size may be measured in any suitable manner,
for example using a glass cell and a Malvern ZetaSizer. With
storing of the ink in an oven at 120.degree. C. and taking particle
size measurements at various times over the course of 30 days, the
particle size for the ink increases by less than 20%, for example
less than 15%, from the particle size of the freshly made ink, when
the amount of the dispersant is reduced in the above amounts in an
ink composition and a synergist is added. In embodiments, the ink
as made may have average particle sizes of from about 150 to about
300 nm.
[0056] The synergist is thus a solid that contains functional
groups that can strongly adsorb onto the pigment. The dispersant,
on the other hand, is soluble, or at least mainly soluble, in a
substantial portion of the ink vehicle. A portion of the dispersant
interacts strongly with the synergist such that the
synergist/dispersant combination is strongly associated to the
surface of the pigment. The combination of the synergist and the
dispersant thus permits the pigment to be effectively dispersed in
the solid ink medium with a desirable reduction in the loading of
the dispersant while maintaining particle size stability over time
at elevated temperatures. Pigmented inks are considered stable when
the particle size growth of the pigment is limited to less than or
equal to 15% after being aged at elevated temperature, for example,
after 30 days at 120.degree. C.
[0057] The dispersant thus comprises at least a portion of itself
that is soluble in the ink vehicle, which includes at least one
functional group that has an affinity for the synergist. Overall,
the dispersant is partially or wholly soluble in the medium, but
the at least one functional group of the dispersant interacts
strongly with the synergist wherein the synergist is strongly
associated to the surface of the pigment. The soluble portion of
the dispersant extends into the ink medium and provides a barrier,
thus preventing or hindering the flocculation of pigment
particles.
[0058] The dispersant generally comprises a portion, such as polar
groups, that interact with the synergist and a portion, for example
a chain, that is compatible with the ink vehicle. Polar groups can
suitably interact with the synergist in any suitable manner, such
as hydrogen bonding, covalent bonding, acid-base reaction, Van der
Waals interactions, and the like. Examples of suitable polar groups
include such functional groups as amines, amides, esters,
sulfonates, carboxylic acids, hydroxyl groups, anhydrides,
urethanes, ureas and salt groups such as quaternary ammonium salts,
and the like. Examples of the portion of the dispersant that is
compatible with the ink vehicle include groups such as alkyl and
alkoxyl groups, which can be linear or branched, saturated or
unsaturated and the like, and may have a chain length of from, for
example, about I to about 50 carbon atoms.
[0059] Specific examples of suitable dispersants are polyester
dispersants such as those disclosed in U.S. Pat. No. 6,702,884 and
U.S. Pat. No. 6,841,590, the disclosures of which are totally
incorporated herein by reference. Dispersants may include
SOLSPERSE.RTM. 16000, SOLSPERSE.RTM. 28000, SOLSPERSE.RTM. 32500,
SOLSPERSE.RTM. 38500, SOLSPERSE.RTM. 39000, SOLSPERSE.RTM. 54000,
SOLSPERSE.RTM. 17000, SOLSPERSE.RTM. 17940, SOLSPERSE.RTM. 13240,
SOLSPERSE.RTM. 19000, as well as mixtures thereof.
[0060] Examples of suitable polyester dispersants are disclosed in
U.S. Pat. No. 3,996,059, the disclosure of which is totally
incorporated herein by reference. The dispersant may be a polyester
of the formula
##STR00006##
wherein each R.sub.1 is an alkylene group, including linear,
branched, saturated, unsaturated, cyclic. substituted, and
unsubstituted alkylene groups containing at least 8 carbon atoms,
such as from about 8 to about 40 carbon atoms or from about 8 to
about 40 or from about 8 to about 20 carbon atoms, although the
numbers can be outside these ranges; X is (i) an oxygen atom, or
(ii) an alkylene group which is attached to the carbonyl group
through an oxygen or nitrogen atom with at least 2 carbon atoms;
R.sub.2 is (i) a hydrogen atom, or (ii) a primary, secondary or
tertiary amine group or a salt thereof with an acid, or a
quaternary ammonium salt group; and n is an integer representing a
number of repeating groups, for example from 2 to about 20 or from
about 2 to about 10.
[0061] Other examples of suitable dispersants include polyalkylene
succinimide dispersants such as those disclosed in U.S. Pat. No.
6,858,070, the disclosure of which is totally incorporated herein
by reference. Dispersants can include the Chevron Oronite OLOA
11000, OLOA 11001, OLOA 11002, OLOA 11005, OLOA 371, OLOA 375, OLOA
411, OLOA 4500, OLOA 46001, OLOA 8800, OLOA 8900, OLOA 9000, OLOA
9200 and the like, commercially available from Chevron Oronite
Company, as well as mixtures thereof. Other suitable dispersants
from Byk-Chemie include examples such as BYK P-105, an unsaturated
polycarboxylic acid, BYK 9076, an alkyl ammonium salt of high
molecular weight co-polymer, BYK 9077, Disperbyk 108, a
hydroxy-functional carboxylic acid ester, Disperbyk 116, an
acrylate co-polymer, Disperbyk 140, a solution of an alkyl ammonium
salt of an acid polymer in 2-methoxy-1-methylethyl acetate,
Disperbyk 168, a solution of a high molecular weight block
copolymer in a dicarboxylic acid ester, Disperbyk 2000, a solution
of a modified acrylate polymer in methoxypropyl acetate, Disperbyk
2001, a solution of a modified acrylate polymer in a mixture of
methoxypropyl acetate, butylglycol and methoxypropanol.
[0062] Some dispersants are dispersed in volatile solvents (from
the supplier), and thus may not be suitable for use directly in
certain mixing apparatuses. These dispersants can be pre-treated to
remove the volatile solvent so that the material may optionally be
used in the desired mixing device. The volatile solvents can be
removed by heating the dispersant at high temperature, for example
at 120.degree. C. (optionally under vacuum) to remove the volatile
solvent before being used for the mixing process.
[0063] In embodiments, a desirable ink composition comprises, in
addition to dispersant and synergist, from about 40 to about 60% by
weight of a polyethylene wax, from about 8 to about 18% by weight
of a triamide resin, from about 10 to about 20% by weight of a
fatty amide, for example stearyl steramide, from about 5 to about
15% by weight of a rosin ester, from about 0.01 to about 3% by
weight of an antioxidant, for example NAUGARD 445, and from about 1
to about 7% by weight of a urethane resin (described in Example 4
of U.S. Pat. No. 6,309,453).
[0064] In embodiments, the ink may be prepared by preparing the
pigment as a concentrate in a suitable mixing apparatus, such as
for example an extruder, kneader, attritor or the like, for
subsequent letdown and high shear mixing, for example,
homogenizing, with other components of the ink vehicle. In
embodiments, in the extrusion process, the synergist, the pigment
and the polar resin from the ink formulation, for example the
triamide resin, are blended together in powder form before being
charged to the extruder. Although the triamide resin may be
considered a dispersant for the pigment(s), the blend at this stage
can be optionally free of dispersants. The resulting extrudate can
then be processed with other ink ingredients to form the phase
change ink. The contents in the extruder may then be mixed at
temperatures of from about 25.degree. C. to about 90.degree. C.,
such as from about 50.degree. C. to about 85.degree. C. or from
about 60.degree. C. to about 80.degree. C. at about 5 RPM to about
600 RPM, such as at about 25 RPM to about 100 RPM or at about 40
RPM to about 65 RPM. This mixing provides the necessary torque to
shear the pigment particles, allowing the polar group of the
synergist to anchor onto the pigment surface. The dispersant may
then subsequently be added to the mixture later in the extrusion
process, or in embodiments, during the ink making process. The
contents are extruded to form an extrudate of the pigment, wherein
the sheared pigment has been wetted by the resins, synergist and/or
dispersant.
[0065] Separate from the extrusion process, the other components of
the ink vehicle, for example including at least the wax component,
are mixed, for example at temperatures of from about 80.degree. C.
to about 150.degree. C., such as from about 80.degree. C. to about
140.degree. C.
[0066] The extrudate and the mixed ink vehicle components are then
processed by stirring or high shear mixing, for example using a
homogenizer or high speed stirrer or the like, to form a stable
pigmented solid phase change ink. The present disclosure is not
restricted in terms of the choice of ink components used during
preparation of the ink concentrate. For example, in some
embodiments, both the synergist and the dispersant may be present
during preparation of the ink concentrate.
[0067] In further embodiments, the mixing of the extrudate with the
remaining components of the ink vehicle may be performed in one or
more stages. For example, the homogenization may comprise a first
homogenization process with the relatively polar component(s) of
the ink and the extrudate, and a second homogenization process
wherein the product of the first homogenization process is mixed
with at least one of the relatively non-polar component of the ink.
Relatively polar components of the ink may include, but are not
limited to, fatty amides (for example, KEMAMIDE S180), and rosin
esters such as a glyceryl abietate (for example, KE-100).
Relatively non-polar components of the ink may include, but are not
limited to, wax such as polyethylene wax. Both homogenization
procedures may be conducted at the same or different temperatures,
for example at temperatures of from about 60.degree. C. to about
150.degree. C., or from about 80.degree. C. to about 120.degree.
C.
[0068] Of course, other processes may also be used to form the ink.
For example, the dispersant may be present in a mixture to which
the pigment is added, with subsequent addition of the synergist
either during preparation of the concentrate or the ink itself.
This can still result in an adequate stabilized dispersion of the
pigment in the ink vehicle, particularly where the synergist has a
stronger affinity for the pigment surface than the dispersant.
Furthermore, alternative means of processing may be used for both
the preparation of the ink concentrate and the ink itself. For
example, the ink concentrates or the inks can be agitated or mixed
by any suitable means, including a mechanical or magnetic stirrer,
a high speed mixer, an attritor, a homogenizer, a sonificator, a
microfluidizer, and the like, with or without an optional grinding
medium, such as stainless steel balls, ceramic chips, and the
like.
[0069] The ink formed may be filtered by any suitable process, for
example by filtering with a screen at temperatures of from about
90.degree. C. to about 150.degree. C. Filtration of the prepared
ink can be performed using various depth filters, such as for
example nylon, polysulfone, and glass fiber filters having absolute
ratings of, for example, 6 microns or 1 micron.
[0070] The inks disclosed herein may exhibit Newtonian behavior
from about 100.degree. C. to 130.degree. C., such as from about
110.degree. C. to about 120.degree. C., at a shear rate of about
10.sup.-2 to about 10.sup.4 s.sup.-1, such as from about 10.sup.-1
to about 10.sup.3 s.sup.-1.
[0071] Phase change ink jet processes are well known and are
described, for example, in U.S. Pat. Nos. 4,601,777, 4,251,824,
4,410,899, 4,412,224 and 4,532,530, the disclosures of which are
incorporated herein by reference in their entirety.
[0072] Ink jetting devices are known in the art. As described in
U.S. Pat. No. 6,547,380, the disclosure of which is totally
incorporated herein by reference, ink jet printing systems are
generally of two types: continuous stream and drop-on-demand. In
continuous stream ink jet systems, ink is emitted in a continuous
stream under pressure through at least one orifice or nozzle. The
stream is perturbed, causing it to break up into droplets at a
fixed distance from the orifice. At the break-up point, the
droplets are charged in accordance with digital data signals and
passed through an electrostatic field that adjusts the trajectory
of each droplet in order to direct it to a gutter for recirculation
or a specific location on a recording medium. In drop-on-demand
systems, a droplet is expelled from an orifice directly to a
position on a recording medium in accordance with digital data
signals. A droplet is not formed or expelled unless it is to be
placed on the recording medium. Different types of drop-on-demand
ink jet systems for non-aqueous inks exist. One type of
drop-on-demand system is a piezoelectric device that has as its
major components an ink filled channel or passageway having a
nozzle on one end and a piezoelectric transducer near the other end
to produce pressure pulses. Another type of drop-on-demand system
is known as acoustic ink printing. As is known, an acoustic beam
exerts a radiation pressure against objects upon which it impinges.
Thus, when an acoustic beam impinges on a free surface (i.e.,
liquid/air interface) 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 tile 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.
[0073] Printed images may be generated with the ink described
herein by incorporating the ink into an ink jet device, for example
an acoustic ink jet device or a piezoelectric ink jet device,
heating the ink to a suitable jetting temperature, and concurrently
causing droplets of the molten ink to be ejected in a pattern onto
a substrate such as an intermediate transfer medium or directly
onto paper or transparency material, which can be recognized as an
image. The ink is typically included in the at least one reservoir
connected by any suitable feeding device to the ejecting channels
and orifices of the ink jet head for ejecting the ink. In the
jetting procedure, the inkjet head may be heated, by any suitable
method, to the jetting temperature of the inks. The phase change
inks are thus transformed from the solid state to a molten state
for jetting. In a typical design of a piezoelectric ink jet device,
the image is applied by jetting appropriately colored inks during
four to eighteen rotations (incremental movements) of a substrate
such as an image receiving member or intermediate transfer member
with respect to the ink jetting head, that is, there is a small
translation of the printhead with respect to the substrate in
between each rotation. This approach simplifies the printhead
design, and the small movements ensure good droplet
registration.
[0074] The inks can also be employed in indirect (offset) printing
inkjet applications, wherein when droplets of the melted ink are
ejected in an imagewise pattern onto a recording substrate, the
recording substrate is an intermediate transfer member and the ink
in the imagewise pattern is subsequently transferred from the
intermediate transfer member to a final recording substrate, such
as paper or transparency.
[0075] Embodiments described above will now be further illustrated
by way of the following examples.
EXAMPLE 1
[0076] Inks were prepared using an attritor for preparation of the
ink concentrate, as summarized below. Ink concentrate 1 was
prepared as follows: a Szegvari 01 Attritor equipped with 1/8 inch
stainless steel balls was heated to 120.degree. C. and charged with
a pre-melted mixture containing triamide resin 6 (113.4 g),
SOLSPERSE.RTM. 13240 (21.0 g), and NAUGARD 445 (0.25 g). To the
stirred mixture was added slowly HOSTAPERM Blue B4G (21.0 g), and
then SOLSPERSE.RTM. 5000 (0.42 g) as the synergist. The mixture was
stirred for 16 hours at a speed of 250 RPM and a temperature of
120.degree. C. A diluent solution of KE100 (36.0 g), KEMAMIDE S-180
(40.5 g), urethane resin (12.0 g), NAUGARD 445 (0.25 g), and
polyethylene wax (156.0 g) was pre-melted at 120.degree. C. The
molten diluent solution was then poured slowly into the stirred ink
concentrate (55.7 g), and stirred at 120.degree. C. for a further 1
hour.
[0077] The ink was filtered and then immediately placed in a glass
cell, used for particle size measurements on a Malvern ZetaSizer.
The cell was stored in an oven at 120.degree. C.; particle size
measurements were taken at various times over the course of 30
days. The particle size for the freshly filtered ink was 234 nm,
and after 30 days aging at 120.degree. C., the particle size was
229 nm.
EXAMPLE 2
[0078] Ink 2 was prepared using the same method as for Example 1,
but the synergist was not added. The particle size for the freshly
filtered ink was 283 nm, and after 30 days aging at 120.degree. C.,
the particle size was 372 nm.
EXAMPLE 3
[0079] Ink 3 was prepared using the same method as for Example 1,
but a reduced amount of SOLSPERSE.RTM. 13240 (13.7 g) was used. The
particle size for the freshly filtered ink was 255 nm, and after 30
days aging at 120.degree. C., the particle size was 282 nm.
[0080] The effect of the synergist can be seen both in terms of
nominal particle size, and particle size stability. The inks
without synergist exhibited larger particle size and size growth
than did the inks containing synergist. Furthermore, addition of
the synergist enabled the use of less dispersant, while maintaining
thermal stability in terms of particle size and particle size
growth.
[0081] It will be appreciated that various of the above-disclosed
and other features and functions, or alternatives thereof, may be
desirably combined into many other different systems or
applications. Also, various presently unforeseen or unanticipated
alternatives, modifications, variations or improvements therein may
be subsequently made by those skilled in the art, and are also
intended to be encompassed by the following claims.
* * * * *