Title: Ink jet ink composition
Abstract: An ink jet ink composition of water, humectant and a self-assembling colorant that is capable of spontaneously forming a nanoparticulate dispersion without any prior physical attrition or surface modification, the colorant having the formula: (A).sub.m --Q--(Z).sub.n wherein: Q represents a chromophore; each A independently represents an organic or inorganic group capable of hydrogen bonding or other non-covalent bonding; each Z independently represents an organic or inorganic group capable of electrostatic bonding; and m and n each independently represents an integer from 0 to 10; with the proviso that n+m is at least 1; and with the further proviso that at least about 50 wt. % of the colorant is present in the composition as particles.
Patent Number: 6,855,193 Issued on 02/15/2005 to Andrievsky, et al.
| Inventors:
|
Andrievsky; Andrei (Webster, NY);
Southby; David T. (Rochester, NY);
Evans; Steven (Rochester, NY);
Decann; Dale E. (Rochester, NY)
|
| Assignee:
|
Eastman Kodak Company (Rochester, NY)
|
| Appl. No.:
|
231836 |
| Filed:
|
August 30, 2002 |
| Current U.S. Class: |
106/31.27; 106/31.43; 106/31.44; 106/31.47; 106/31.49; 106/31.6; 106/31.75; 106/31.77; 106/31.78 |
| Intern'l Class: |
C09D 011//02 |
| Field of Search: |
106/31.27,31.43,31.44,31.47,31.49,31.6,31.75,31.77,31.78
|
References Cited [Referenced By]
U.S. Patent Documents
| 4732615 | Mar., 1988 | Kawashita et al. | 106/31.
|
| 5368641 | Nov., 1994 | Dietz et al. | 106/495.
|
| 5571311 | Nov., 1996 | Belmont et al. | 106/31.
|
| 5630868 | May., 1997 | Belmont et al. | 106/31.
|
| 5707432 | Jan., 1998 | Adams et al. | 106/31.
|
| 5830265 | Nov., 1998 | Tsang et al. | 106/31.
|
| 5922118 | Jul., 1999 | Johnson et al. | 106/31.
|
| 5994427 | Nov., 1999 | Kappele et al. | 523/160.
|
| 6066203 | May., 2000 | Badejo et al. | 106/497.
|
| 6152968 | Nov., 2000 | Etzbach et al. | 8/638.
|
| 2003/0209166 | Nov., 2003 | Vanmaele et al. | 106/31.
|
| Foreign Patent Documents |
| 0559309 | Mar., 1988 | EP.
| |
| 0 904 327 | Aug., 2001 | EP.
| |
| 1 146094 | Oct., 2001 | EP.
| |
| WO 97/47699 | Dec., 1997 | WO.
| |
Primary Examiner: Klemanski; Helene
Attorney, Agent or Firm: Cole; Harold E., Konkol; Chris P.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
Reference is made to commonly assigned, co-pending U.S. patent
applications:
Ser. No. 10/231,837 by Andrievsky et al., filed concurrently herewith
entitled "Ink Jet Printing Process";
Ser. No. 10/232,035 by Andrievsky et al., filed concurrently herewith
entitled "Ink Jet Ink Composition"; and
Ser. No. 10/232,058 by Andrievsky et al., filed concurrently herewith
entitled "Ink Jet Printing Process".
Claims
What is claimed is:
1. An ink jet ink composition comprising water, humectant and a
nanoparticulate dispersion that is the product of self-assembling colorant
molecules that spontaneously form the nanoparticulate dispersion without
any prior physical attrition or prior surface modification, said
self-assembling colorant molecules each represented by the formula:
(A).sub.m --Q--(Z).sub.n
wherein:
Q represents a chromophore;
each A independently represents an organic or inorganic non-ionic,
hydrophilic group capable of hydrogen bonding or other non-covalent
bonding to form the nanoparticulate dispersion;
each Z independently represents an organic or inorganic water-solubilizing
group capable of electrostatic bonding to form the nanoparticulate
dispersion; and
m and n each independently represents an integer from 0 to 10;
with the proviso that n+m is at least 1; and with the further proviso that
at least about 50 wt. % of the colorant is present in the composition as
particles.
2. The composition of claim 1 wherein said Q represents a colorant selected
from the class consisting of anthraquinone, naphthoquinone, quinacridone,
quinophthalone, indigo, thioindigo, perylene, dioxazine,
1,4-diketopyrrolopyrrole, anthrapyridine, anthrapyrimidine, anthanthrone,
flavanthrone, indanthrone, isoindoline, isoindolinone, perinone,
pyranthrone, porphyrin, and azo chromophores.
3. The composition of claim 1 wherein each said Z independently represents
sulfonate, sulfinate, phosphonate, carboxylate, ammonium, substituted
ammonium, pyridinium, amidinium or guanidinium.
4. The composition of claim 1 wherein each said A independently represents
hydroxy, a sugar residue, a polyoxyalkylene group, a sulfamoyl or
carbamoyl group and its mono- and di-substituted derivatives, a
heterocyclic group or an alkylsulfonyl group.
5. The composition of claim 1 wherein said colorant is present in an amount
of from about 0.2 to about 10 wt. %, said humectant is present in an
amount of from about 5 to about 70 wt. %, and the balance is water.
6. The composition of claim 1 which also includes a water-soluble dye.
7. The composition of claim 1 wherein said particles are less than about
0.3 .mu.m in size.
8. The composition of claim 1 wherein said particles are less than about
0.1 .mu.m in size.
9. The composition of claim 1 wherein said colorant has the formula:
##STR11##
wherein:
each R.sub.1 independently represents an alkyl group of from 1 to about 6
carbon atoms, an alkoxy group of from 1 to about 6 carbon atoms, an
alkoxycarbonyl group of from 1 to about 6 carbon atoms, halogen, cyano,
nitro, carbamoyl, alkylsulfonyl, an alkylcarbamoyl group of from 1 to
about 6 carbon atoms or a dialkylcarbamoyl group of from 1 to about 6
carbon atoms;
R.sub.2 and R.sub.3 each independently represents H or an alkyl group of
from 1 to about 6 carbon atoms, optionally substituted with one or more
groups selected from the group consisting of hydroxy, amino, dialkylamino,
alkoxy, halogen, nitro, cyano, alkoxycabonyl and acyloxy;
R.sub.2 and R.sub.3 may also be part of a 5- to 7-membered heterocyclic
ring;
x represents an integer from 0 to 4; and
Y represents hydrogen, alkali metal or an organic cation.
10. The composition of claim 1 wherein the particles are less than 0.3
.mu.m in size.
11. The composition of claim 1 wherein the particles are less than about
0.1 .mu.m in size.
Description
FIELD OF THE INVENTION
This invention relates to an ink jet ink composition for improving the
ozone and light stability of an ink jet image.
BACKGROUND OF THE INVENTION
Ink jet printing is a non-impact method for producing images by the
deposition of ink droplets in a pixel-by-pixel manner to an
image-recording element in response to digital signals. There are various
methods that may be utilized to control the deposition of ink droplets on
the image-recording element to yield the desired image. In one process,
known as continuous ink jet, a continuous stream of droplets is charged
and deflected in an imagewise manner onto the surface of the
image-recording element, while unimaged droplets are caught and returned
to an ink sump. In another process, known as drop-on-demand ink jet,
individual ink droplets are projected as needed onto the image-recording
element to form the desired image. Common methods of controlling the
projection of ink droplets in drop-on-demand printing include
piezoelectric transducers and thermal bubble formation. Ink jet printers
have found broad applications across markets ranging from industrial
labeling to short run printing to desktop document and pictorial imaging.
The inks used in the various ink jet printers can be classified as either
dye-based or pigment-based. A dye is a colorant that is molecularly
dispersed or solvated by a carrier medium. The carrier medium can be a
liquid or a solid at room temperature. A commonly used carrier medium is
water or a mixture of water and organic co-solvents. Each individual dye
molecule is surrounded by molecules of the carrier medium. In dye-based
inks, no particles are observable under the microscope. Although there
have been many recent advances in the art of dye-based ink jet inks, such
inks still suffer from deficiencies such as low optical densities on plain
paper and poor light-fastness. When water is used as the carrier medium,
such inks also generally suffer from poor water-fastness.
A pigment is a colorant that is insoluble in the carrier medium, but is
dispersed or suspended in the form of small particles, often stabilized
against flocculation and settling by the use of dispersing agents. Many
such compounds are known and are commercially used. Color Index
International (publication by the Society of Dyers and Colorists, 1997)
lists various classes of pigments. It is common practice to produce
pigment compositions in the form of finely divided dispersions, which may
be generated by well-known methods such as ball milling. In order to
obtain the optimum dispersion properties it is common to have present at
least one dispersant, and the choice of dispersant is important for
achieving acceptable pigment dispersion properties. The purpose of the
dispersant is to stabilize the particles and to prevent growth by
aggregation and flocculation. However, merely adsorbing a dispersant to
the pigment surface may lead to competition for such dispersant from
solvents and humectants used in the ink formulation and may lead to
desorption. In general, such systems may also suffer from a dependence on
the concentration of the pigment, the type of humectants used, and the
temperature and pH of the formulation containing the pigment. Therefore,
it is often difficult to identify an acceptable dispersant which provides
the needed ink stability and is compatible with other components in the
ink formulation.
Images obtained from pigment-based inks generally have better
light-fastness and ozone-fastness than that of the images obtained from
dye-based inks. It is especially true when these are used with a recording
element containing a porous image-receiving layer. However, pigment based
inks have not received a wide degree of acceptance in ink jet ink systems,
because of problems associated with the preparation, performance and
reliability of the composition, such as dispersability, print properties,
dispersion stability, latency, smear, and gloss.
When a pigment-based ink is formulated, a dispersant is normally used along
with a milling or physical grinding step. Alternatively, after milling,
the pigment surface may be chemically modified to render the particles
dispersible in an aqueous formulation. However, there is a problem with
these techniques in that they take time and are expensive. It would be
desirable to find alternative colorants having the image permanence of
pigments but which do not require milling.
U.S. Pat. No. 5,922,118, EPA 0904327, and WO9747699 disclose
surface-modified pigments, wherein such surface modification comprises
ionic or ionizable groups for improvement of pigment dispersability.
However, these pigments still require a milling step.
EP 1146094 describes pigment compositions for paints and inks consisting of
mixtures of salts of quinacridone monosulfonic acids and quinacridone
pigments. The quinacridone monosulfonic acid derivatives of this reference
are not water-soluble and the pigment compositions require mechanical
milling to achieve acceptable dispersions.
U.S. Pat. Nos. 6,066,203 and 5,368,641 describe mono- and bis-sulfamoyl
(--SO.sub.2 NRR') derivatives (respectively) of quinacridones for use in
formulating quinacridone pigment dispersions similar to those described in
EP1146094 above.
It is an object of the invention to provide an ink jet ink composition that
employs self-dispersed particles, which do not require milling or grinding
and do not require the use of a dispersant.
SUMMARY OF THE INVENTION
This and other objects are achieved in accordance with the present
invention which comprises an ink jet ink composition comprising water,
humectant and a self-assembling colorant that is capable of spontaneously
forming a nanoparticulate dispersion without any prior physical attrition
or surface modification, the colorant having the formula:
(A).sub.m --Q--(Z).sub.n
wherein:
Q represents a chromophore;
each A independently represents an organic or inorganic group capable of
hydrogen bonding or other non-covalent bonding;
each Z independently represents an organic or inorganic group capable of
electrostatic bonding; and
m and n each independently represents an integer from 0 to 10;
with the proviso that n+m is at least 1; and with the further proviso that
at least about 50 wt. % of the colorant is present in the composition as
particles.
It was found that the stability to atmospheric pollutants and to light of
an ink jet image was improved using the compositions described herein.
DETAILED DESCRIPTION OF THE INVENTION
The chromophore (Q) of the colorant of the invention may be chosen from any
of the commonly used dye and pigment chromophoric classes. In particular,
those classes that are capable of self-assembling through strong
intermolecular non-covalent associative forces such as electrostatic
bonding, van der Waals interactions, hydrogen bonding, hydrophobic
interactions, dipole-dipole interactions, dipole-induced dipole
interactions, London dispersion forces, cation--.pi. interactions, etc.
are especially preferred. Self-assembly is a process of reversible,
spontaneous formation of polymolecular aggregates from self-complementary
and mutually-complimentary components. Examples of such classes include
the following chromophores: metal and metal-free phthalocyanines;
anthraquinones; naphthoquinones; quinacridones; quinophthalones; indigos;
thioindigos; perylenes; dioxazines; 1,4-diketopyrrolopyrroles;
anthrapyridines; anthrapyrimidines; anthanthrones; flavanthrones;
indanthrones; isoindolines; isoindolinones; perinones; pyranthrones;
porphyrins and azo compounds.
In a preferred embodiment of the invention, the colorant is substituted
with a mixture of organic or inorganic water-solubilizing group or groups
capable of electrostatic bonding (Z) and/or organic or inorganic
hydrophilic non-ionic groups capable of hydrogen bonding or other
non-covalent bonding (A) in such a ratio that the colorant spontaneously
forms a nanoparticulate dispersion in an aqueous carrier liquid without
prior attritive milling or other high-energy dispersing techniques or
prior surface modification. The ionic water-solubilizing groups (Z) may be
anionic, such as sulfonate, sulfinate, phosphonate or carboxylate; or
cationic such as ammonium, substituted ammonium, pyridinium, amidinium or
guanidinium. The non-ionic, hydrophilic groups (A) may be hydroxy groups,
sugar residues, polyoxyalkylene groups such as poly(ethyleneoxide),
sulfamoyl or carbamoyl groups and their mono- and di-substituted
derivatives, heterocyclic moieties such as tetrahydrofuran, imidazole and
the like, or alkylsulfonyl groups.
In a particularly preferred embodiment, the ionic water-solubilizing groups
(Z) are sulfonate groups and non-ionic hydrophilic groups (A) are mono- or
di-substituted sulfamoyl groups.
Particularly preferred colorant classes are the phthalocyanines and
quinacridones with the following formulas:
Phthalocyanine-MPc(SO.sub.3 X).sub.a (SO.sub.2 NRR').sub.b
wherein:
M represents a metal;
Pc represents a phthalocyanine nucleus;
X represents hydrogen, alkali metal or an organic cation, such as Na, Li,
or ammonium;
a is from 0 to 3;
R represents a substituted or unsubstituted alkyl group having from 1 to
about 15 carbon atoms, a substituted or unsubstituted aryl group, or a
substituted or unsubstituted heterocyclic group;
R' represents R or hydrogen;
with the proviso that a+b is an average of from 2 to 4;
In an especially preferred embodiment of the invention, R in the above
formula represents a substituted or unsubstituted alkyl group having from
1 to about 15 carbon atoms containing a hydroxy group, a substituted or
unsubstituted aryl group containing a hydroxy group or a substituted or
unsubstituted heterocyclic group containing a hydroxy group. In another
preferred embodiment, M in the above formula represents copper, nickel,
aluminum, zinc, iron, or cobalt. In another preferred embodiment, R in the
above formula represents CH.sub.2 CH.sub.2 OH. In another preferred
embodiment, M represents Cu or Ni and R is CH.sub.2 CH.sub.2 OH.
Quinacridone
##STR1##
wherein:
each R.sub.1 independently represents an alkyl group of from 1 to about 6
carbons; an alkoxy group of from 1 to about 6 carbons; an alkoxycarbonyl
group of from 1 to about 6 carbons; halogen; cyano; nitro; carbamoyl; an
alkylcarbamoyl group of from 1 to about 6 carbons; or a dialkylcarbamoyl
group of from 1 to about 6 carbons;
R.sub.2 and R.sub.3 independently represent H or an alkyl group of from 1
to about 6 carbons, optionally substituted with one or more groups chosen
from hydroxy, amino, dialkylamino, alkoxy, halogen, nitro, cyano,
alkoxycarbonyl and acyloxy.
R.sub.2 and R.sub.3 may also be combined to form a 5- to 7-membered
heterocyclic ring;
Y.sup.+ represents hydrogen, an alkali metal, ammonium, alkylammonium,
diallcylammonium, trialkylammonium, tetralkylammonium, pyridinium or a
substituted pyridinium; and
x represents an integer from 0 to 4;
In another preferred embodiment, at least about 70 wt. %, more preferably
80 wt. % of the colorant is present in the composition as particles. In
another preferred embodiment, the particles are less than about 0.3 .mu.m,
more preferably less than about 0.1 .mu.m in size.
In another preferred embodiment of the invention, the metallized,
phthalocyanine colorants that may be used include the following:
TABLE 1a
##STR2##
Colorant M Z.sub.1 Z.sub.2 Z.sub.3 Z.sub.4 Substitution
1 Cu DA DA DA DA 4, 4', 4", 4'''
2 Cu SX DA DA DA 4, 4', 4", 4'''
3 Cu SX SX DA DA 4, 4', 4", 4'''
4 Cu SX SX SX DA 4, 4', 4", 4'''
5 Cu DA DA DA DA random
6 Cu SX DA DA DA random
7 Cu SX SX DA DA random
8 Cu SX SX SX DA random
9 Cu DA DA DA N/S random
10 Cu SX DA DA N/S random
11 Cu SX SX DA N/S random
12 Cu DA DA N/S N/S random
13 Cu SX DA N/S N/S random
14 Ni DA DA DA DA 4, 4', 4", 4'''
15 Ni SX DA DA DA 4, 4', 4", 4'''
16 Ni SX SX DA DA 4, 4', 4", 4'''
17 Ni SX SX SX DA 4, 4', 4", 4'''
18 Cu EA EA EA EA 4, 4', 4", 4'''
19 Cu SEA BA BA BA random
20 Ni SEA SEA BA BA 4, 4', 4", 4'''
21 Ni SEA SEA SEA EA random
22 Cu EA EA EA DA 4, 4', 4", 4'''
23 Cu SEA EA EA DA random
24 Ni SEA SEA EA EA 4, 4', 4", 4'''
25 Co SEA SEA SEA EA random
26 Cu DA DA EA N/S random
27 Cu SX DA EA N/S random
28 Cu SX SEA DA N/S random
29 Cu DA EA N/S N/S random
30 Ni SX DA N/S N/S random
31 Cu SPY SPY SPY SNa random
32 Cu SPY SPY SPH SNa random
33 Ni SPY SPY SNa SNa random
34 Ni SPY SPY SPH SNa random
35 Cu SPY SPY SPH SNa 4, 4', 4", 4'''
36 Ni SPY SPY SPH SNa 4, 4', 4", 4'''
Where:
SX=SO.sub.3.sup.- H.sub.2 N.sup.+ (CH.sub.2 CH.sub.2 OH).sub.2 ;
DA=SO.sub.2 N(CH.sub.2 CH.sub.2 OH).sub.2 ;
EA=SO.sub.2 NHCH.sub.2 CH.sub.2 OH;
SEA=SO.sub.3.sup.- H.sub.3 N.sup.+ CH.sub.2 CH.sub.2 OH;
##STR3##
SNa=SO.sub.3.sup.- Na.sup.+
N/S=no substituent.
Electrophilic substitution or construction of the phthalocyanine nucleus
leads to a mixture of products. In each aromatic ring, as shown in the
generalized structure below, substitution may occur at one of the 4 or 4a
positions, which are equivalent, or at one of the 3 or 3a positions, which
are equivalent.
Numbering of position of substitution
##STR4##
The descriptors in Table 1a, `Substitution` column have the following
meanings: 4, 4', 4", 4'": substitution occurred to give one substituent in
each aromatic ring at a 4 or 4a position; random: where substitution
occurred, the substituent is present in one of the 3, 4, 4a or 3a
positions in each aromatic ring.
Colorant A Composition is predominantly a mixture of Colorants 1-4 and
includes positional isomers of Colorants 1-4;
Colorant B Composition is predominantly a mixture of Colorants 5-13 and
includes positional isomers of Colorants 5-13;
Colorant C Composition is predominantly a mixture of Colorants 14-17 and
includes positional isomers of Colorants 14-17.
In another preferred embodiment of the invention, the quinacridone
colorants that may be used include the following:
TABLE 1b
##STR5##
Col-
or-
ant M.sup.+ R.sub.1 R.sub.2
37 H.sub.2 N.sup.+ (C.sub.2 H.sub.4 OH).sub.2 C.sub.2 H.sub.4 OH
C.sub.2 H.sub.4 OH
38 H.sub.3 N.sup.+ C.sub.2 H.sub.4 OH H C.sub.2 H.sub.4
OH
39 Na.sup.+ CH.sub.3 C.sub.2 H.sub.4 OH
40 N.sup.+ (CH.sub.3).sub.4 H CH.sub.2 CH(OH)CH.sub.2
OH
41 Na.sup.+ CH.sub.3 CH.sub.3
42 Na.sup.+ H C.sub.3 H.sub.6 N(CH.sub.3).sub.2
43 Na.sup.+ C.sub.2 H.sub.4 CO.sub.2 CH.sub.3 C.sub.2 H.sub.4
CO.sub.2 CH.sub.3
44 Na.sup.+ H CH.sub.2 [CH(OH)].sub.4 CH.sub.2 OH
45 NH.sub.4.sup.+ H H
46 Na.sup.+ C.sub.2 H.sub.4 CONHCH.sub.3 C.sub.2 H.sub.4
CONHCH.sub.3
47 ##STR6## --C.sub.2 H.sub.4 OC.sub.2 H.sub.4 --
48 ##STR7## --C.sub.4 H.sub.8 --
49 ##STR8##
50 ##STR9##
Colorant D Composition is predominantly Colorant 37
The colorants described above may be employed in any amount effective for
the intended purpose. In general, good results have been obtained when the
colorant is present in an amount of from about 0.2 to about 10 wt. %, the
humectant is present in an amount of from about 5 to about 70 wt. %, and
the balance is water. A dye may also be added to the ink jet ink
composition if desired.
The support for the ink jet recording element used in the invention can be
any of those usually used for ink jet receivers, such as paper,
resin-coated paper, plastics such as a polyester-type resin such as
poly(ethylene terephthalate), polycarbonate resins, polysulfone resins,
methacrylic resins, cellophane, acetate plastics, cellulose diacetate,
cellulose triacetate, vinyl chloride resins, poly(ethylene naphthalate),
polyester diacetate, various glass materials, and microporous materials
such as microvoided polyester described in copending U.S. Ser. No.
09/656,129, filed Aug. 29, 2000, polyethylene polymer-containing material
sold by PPG Industries, Inc., Pittsburgh, Pa. under the trade name of
Teslin.RTM., Tyvek.RTM. synthetic paper (DuPont Corp.), and OPPalyte.RTM.
films (Mobil Chemical Co.) and other composite films listed in U.S. Pat.
No. 5,244,861. The thickness of the support employed in the invention can
be, for example, from about 12 to about 500 .mu.m, preferably from about
75 to about 300 .mu.m.
Antioxidants, antistatic agents, plasticizers and other known additives may
be incorporated into the support, if desired. In a preferred embodiment,
paper is employed.
In a preferred embodiment of the invention, the ink-receiving layer is
porous and contains inorganic particles such as silica, alumina, titanium
dioxide, clay, calcium carbonate, barium sulfate, or zinc oxide. In
another preferred embodiment, the porous ink-receiving layer comprises
from about 20 wt. % to about 95 wt. % inorganic particles, preferably at
least 30 wt. %, and from about 5 wt. % to about 80 wt. %, preferably not
more than 70 wt. %, of polymeric binder, such as gelatin, poly(vinyl
alcohol), poly(vinyl pyrrolidinone) or poly(vinyl acetate). The porous
ink-receiving layer can also contain organic beads or polymeric
micro-porous structures without inorganic filler particles as shown in
U.S. Pat. Nos. 5,374,475 and 4,954,395, the disclosures of which are
hereby incorporated by reference.
Examples of binders which may be used in the image-receiving layer include
polyvinyl alcohol, polyvinyl pyrrolidone, poly(ethyl oxazoline),
non-deionized or deionized Type IV bone gelatin, acid processed ossein
gelatin or pig skin gelatin. The hydrophilic polymer may be present in an
amount of from about 0.4 to about 30 g/m.sup.2, preferably from about 1 to
about 16 g/m.sup.2.
The pH of the aqueous ink compositions of the invention may be adjusted by
the addition of organic or inorganic acids or bases. Useful inks may have
a preferred pH of from about 2 to 9, depending upon the type of dye being
used. Typical inorganic acids include hydrochloric, phosphoric and
sulfuric acids. Typical organic acids include methanesulfonic, acetic and
lactic acids. Typical inorganic bases include alkali metal hydroxides and
carbonates. Typical organic bases include ammonia, triethanolamine and
tetramethylethylenediamine.
One or more humectants are employed in the ink jet composition of the
invention to help prevent the ink from drying out or crusting in the
orifices of the printhead. Examples of humectants which can be used
include polyhydric alcohols, such as ethylene glycol, diethylene glycol,
triethylene glycol, propylene glycol, tetraethylene glycol, polyethylene
glycol, glycerol, 2-methyl-2,4-pentanediol 1,2,6-hexanetriol and
thioglycol; lower alkyl mono- or di-ethers derived from alkylene glycols,
such as ethylene glycol mono-methyl or mono-ethyl ether, diethylene glycol
mono-methyl or mono-ethyl ether, propylene glycol mono-methyl or
mono-ethyl ether, triethylene glycol mono-methyl or mono-ethyl ether,
diethylene glycol di-methyl or di-ethyl ether, and diethylene glycol
monobutylether; nitrogen-containing cyclic compounds, such as pyrrolidone,
N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone; and
sulfur-containing compounds such as dimethyl sulfoxide and tetramethylene
sulfone. Preferred humectants for the composition of the invention are
diethylene glycol, glycerol, and diethylene glycol monobutylether.
Water-miscible organic solvents may also be added to the aqueous ink of the
invention to help the ink penetrate the receiving substrate, especially
when the substrate is a highly sized paper. Examples of such solvents
include alcohols, such as methyl alcohol, ethyl alcohol, n-propyl alcohol,
isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, t-butyl alcohol,
iso-butyl alcohol, furfuryl alcohol, and tetrahydrofurfuryl alcohol;
ketones or ketoalcohols such as acetone, methyl ethyl ketone and diacetone
alcohol; ethers, such as tetrahydrofuran and dioxane; and esters, such as,
ethyl lactate, ethylene carbonate and propylene carbonate.
Surfactants may be added to adjust the surface tension of the ink to an
appropriate level. The surfactants may be anionic, cationic, amphoteric or
nonionic. A preferred surfactant for the ink composition of the present
invention is Surfynol.RTM. 465 (Air Products) at a final concentration of
0.1% to 1.0%.
A biocide may be added to the composition of the invention to suppress the
growth of micro-organisms such as molds, fungi, etc. in aqueous inks. A
preferred biocide for the ink composition of the present invention is
Proxel.RTM. GXL (Zeneca Specialties Co.) at a final concentration of
0.05-0.5 wt. %.
A typical ink composition of the invention may comprise, for example, the
following substituents by weight: colorant (0.2-5%), water (20-95%),
humectant (5-70%), water miscible co-solvents (2-20%), surfactant
(0.1-10%), biocide (0.05-5%) and pH control agents (0.1-10%).
Additional additives which may optionally be present in the ink jet ink
composition of the invention include thickeners, conductivity enhancing
agents, anti-kogation agents, drying agents, and defoamers.
The image-recording layer used in a process employing the composition of
the present invention can also contain various known additives, including
matting agents such as titanium dioxide, zinc oxide, silica and polymeric
beads such as crosslinked poly(methyl methacrylate) or polystyrene beads
for the purposes of contributing to the non-blocking characteristics and
to control the smudge resistance thereof; surfactants such as non-ionic,
hydrocarbon or fluorocarbon surfactants or cationic surfactants, such as
quaternary ammonium salts; fluorescent dyes; pH controllers; anti-foaming
agents; lubricants; preservatives; viscosity modifiers; dye-fixing agents;
waterproofing agents; dispersing agents; UV-absorbing agents;
mildew-proofing agents; mordants; antistatic agents, anti-oxidants,
optical brighteners, and the like. A hardener may also be added to the
ink-receiving layer if desired.
In order to improve the adhesion of the image-recording layer to the
support, the surface of the support may be subjected to a treatment such
as a corona-discharge-treatment prior to applying the image-recording
layer.
In addition, a subbing layer, such as a layer formed from a halogenated
phenol or a partially hydrolyzed vinyl chloride-vinyl acetate copolymer
can be applied to the surface of the support to increase adhesion of the
image recording layer. If a subbing layer is used, it should have a
thickness (i.e., a dry coat thickness) of less than about 2 .mu.m.
The image-recording layer may be present in any amount which is effective
for the intended purpose. In general, good results are obtained when it is
present in an amount of from about 2 to about 46 g/m.sup.2, preferably
from about 6 to about 16 g/m.sup.2, which corresponds to a dry thickness
of about 2 to about 42 .mu.m, preferably about 6 to about 15 .mu.m.
The following examples are provided to illustrate the invention.
EXAMPLES
Synthesis of Colorant A Composition
Colorant A Composition was prepared from Copper (II) phthalocyanine
4,4',4",4'"-tetrasulfonic acid or its salts which was made according to
JP00303009A.
Copper (II) phthalocyanine 4,4',4",4'"-tetrasulfonic acid (5 g) was
suspended in sulfolane (100 ml), and thionyl chloride (100 ml) was added
all at once followed by dimethylformamide (0.5 g). The mixture was
refluxed for 48 hours, insolubles were filtered off and discarded, and
excess thionyl chloride was evaporated using a rotary evaporator.
Diethanolamine (19 g) was then added while stirring and keeping the
reaction temperature between 45 and 55.degree. C. After stirring for 2
hours at 55.degree. C., diisopropyl ether (250 ml) was added to the
resulting reaction mixture, and stirring was continued for 2 hours at
ambient temperature. The colorless layer was decanted, and isopropyl
alcohol (250 ml) was added. The mixture was stirred for 6 hrs at ambient
temperature. The precipitate was filtered, washed with ethanol (200 ml) at
70.degree. C. and dried in vacuo to give Colorant A Composition (4.3 g).
Synthesis of Colorant B Composition
Colorant B Composition was made the same as Colorant A Composition except
Direct Blue 199, sulfonated copper phthalocyanine dye, obtained by freeze
drying an aqueous solution available from Tricon, Inc. was used as the
starting material.
Synthesis of Colorant C Composition
Colorant C Composition was made the same as Colorant A Composition except
Nickel (II) phthalocyanine 4,4',4",4'"-tetrasulfonic acid was used as the
starting material.
Synthesis of Colorant D Composition
10 g of quinacridone (PV Fast Red ESB available from Clariant Corporation)
was added in portions to 100 g of chlorosulfonic acid at <15.degree. C.
under a nitrogen atmosphere. The resulting purple solution was heated in
an 80.degree. C. oil bath for 3 hours, 5 mL thionyl chloride was added and
heating continued at 80.degree. C. for 2 more hours. The reaction mixture
was transferred to a rotary evaporator and the volatiles removed at
50.degree. C. The residue was cooled to room temperature and slowly added
to 400 g of ice with good mixing. The resulting red-orange solid was
collected by filtration and rinsed with cold water. The solid cake was
allowed to air-dry overnight, ground with a mortar and pestle, slurried
with acetone and filtered to yield crude quinacridone bis-sulfonyl
chloride.
10 g of the crude sulfonyl chloride from above was added in portions to a
solution of 9.2 g diethanolamine in 100 mL DMF at <15.degree. C. The
resulting suspension was stirred at ambient temperature for 3 hours and
added to 400 mL methanol with stirring. The solid product was collected by
filtration and rinsed with methanol. The methanol-DMF soluble fraction is
mainly quinacridone bis-sulfonate. The crude product was further purified
by re-suspension in 50 mL warm DMF, dilution with 100 mL methanol, cooling
to room temperature and filtration. The solid was ground with a mortar and
pestle and slurried in acetonitrile to yield 10.2 g of a red-orange solid.
Mass spectral and HPLC analyses indicated that the product was
predominately Colorant 37, with traces of bis-sulfonate and
bis-(diethanolsulfonamide) products.
Receiving Elements
The following commercially-available receiving elements with a porous
image-receiving layer were used:
Receiving Element 1
Kodak Professional Inkjet Products, Instant-Dry Photographic Glossy Paper,
CAT 8987752.
Receiving Element 2
Konica Photo Quality Ink Jet Paper QP, No: KJP-LT-GH-15-QP PI.
Ink Preparation
Inks were formulated to give a maximum density of approximately 1.2-1.4,
when printed onto the above receiving elements using a Lexmark Z51.RTM.,
thermal head printer. The concentration of colorants in the formulation
could be adjusted to achieve other levels of coverage. Inks for printing
via a Piezo head using a Mutoh 4100.RTM. wide format printer are described
hereinafter.
Thermal Cyan Ink Formulations
1) Ink from Colorant C Composition
Colorant C Composition (0.338 g) was stirred overnight with water (2 g) and
a solution (5 g) containing glycerol (37% by weight), diethylene glycol
(12.5%), and butoxytriglycol (14%) in water (to 100%). Once no solids
remained, a further quantity of water (2.66 g) was added to generate 10 g
of ink. This ink was filtered through a 0.45 .mu.m polytetrafluoroethylene
filter pad then loaded into a Lexmark cartridge to be printed using a
Lexmark Z51.RTM. printer.
2) Ink from Colorant C Composition/Direct Blue 199 (Tricon, Inc. Green
Shade 1837-P) Mixture
10 g sample of ink was prepared similar to 1) from Colorant C Composition
(0.169 g) and DB-199 concentrate (1.171 g).
3) Ink from Colorant A Composition
10 g sample of ink was prepared similar to 1) from Colorant A Composition
(0.21 g) to print to a maximum density of approximately 1.0.
4) Ink from Colorant B Composition
10 g sample of ink was prepared similar to 1) from Colorant B Composition
(0.21 g) to print to a maximum density of approximately 1.0.
C-1 Comparison Ink from Direct Blue 199 (Tricon, Inc. Green Shade 1837-P)
10 g sample of ink was prepared similar to 1) from the dye aqueous DB-199
concentrate (2.342 g).
C-2 Comparison Ink from Avecia Pro-Jet.TM. Fast Cyan 2 (Liquid)
10 g sample of ink was prepared similar to 1) from the dye aqueous
concentrate (1.523 g).
C-3 Ink from Bayer Bayscript Cyan BA.TM.
10 g sample of ink was prepared similar to 1) from the dye aqueous
concentrate (0.9 g).
Piezo Light Cyan Ink Formulations
These were prepared to have viscosity in the range of 2.8-3.0 cp and were
adjusted to a pH of about 8.1.
5) Ink from Colorant A Composition
For 80 g of ink, Colorant A Composition (1.6 g) was stirred overnight with
a mixture of glycerol (3.44 g), diethylene glycol (6.8 g), butoxytriglycol
(6.4 g), 2-pyrrolidinone (3.44 g) and water (58.32 g). The pH of the
mixture was measured and adjusted to pH=8.18 by careful addition of a
dilute solution of triethanolamine. The mixture was filtered through a
0.45 .mu.m polytetrafluoroethylene filter pad then loaded ready for
printing using a Mutoh 4100.RTM., wide format printer.
6) Ink from Colorant B Composition
This ink was prepared the same as 5) above except using the dye (1.6 g),
glycerol (8.0 g), diethylene glycol (8.0 g), butoxytriglycol (6.4 g), and
water (56.0 g).
C-4 Comparison Ink from Avecia Pro-Jet.TM. Fast Cyan 2 (Liquid)
This ink was prepared the same as 5) above except using the dye concentrate
(6% dye, 16 g), glycerol (9.4 g), diethylene glycol (10.8 g),
butoxytriglycol (5.6 g), and water (38.2 g).
Thermal Magenta Ink Formulations
7) Ink from Colorant D Composition
Colorant D Composition (0.817 g) was stirred overnight with water (2 g) and
a solution (5 g) containing tetraethylene glycol (30% by weight),
2-pyrrolidinone (16%), and 1,2-hexanediol (14%) in water (to 100%). A
further quantity of water (1.68 g) and triethanolamine (0.5 g) were added
to generate 10 g of ink. This ink was filtered through a 0.45 .mu.m
polytetrafluoroethylene filter pad then loaded into a Lexmark cartridge to
be printed using a Lexmark Z51.RTM. printer.
C-5 Comparison Ink from Ex. 2 of U.S. Pat. No. 6,152,968 (Structure Shown
Below)
##STR10##
10 g sample of ink was prepared similar to 7) from this colorant (0.937 g),
water (2 g+1.56 g), triethanolamine (0.5 g) and a solution (5 g)
containing tetraethylene glycol (30% by weight), 2-pyrrolidinone (16%),
and 1,2-hexanediol (14%) in water (to 100%).
Evaluation
Various test targets were printed, using two ink jet receiving elements, to
allow examination of several density level patches (approx 10 mm square)
ranging from 100% dot coverage to less than 25% dot coverage. Printed
samples were then subjected to image stability testing under a variety of
conditions. These tests are described below. Typically the Status A red
(for cyans) or green (for magentas) reflection density of the 100% and 75%
dot coverage (or other) patches on a fresh sample were measured using an
X-Rite 820.RTM. densitometer, corrected for the color of the receiver, and
recorded. That sample was subjected to a test described below and re-read.
The percentage of dye density remaining relative to the fresh sample was
calculated, to give a measure of colorant fastness on a particular
receiver. These data are given in the Tables below.
Atmospheric Contaminants Test
Printed samples were mounted in a darkened chamber maintained at room
temperature, with a constant atmosphere containing 5 ppm of Ozone, and at
a relative humidity of approximately 50%. The samples were removed after a
time period of 24 hours. The results are shown in the Tables below.
High Intensity Simulated Daylight Fading (HID) Test
Samples were mounted in a temperature and humidity controlled chamber where
they were subjected to 50 Klux light exposure from a filtered xenon light
source, designed to match the spectral characteristics of daylight, for a
period of two weeks. The results are shown in the Tables below.
Printing of Test Images Using a Thermal Head
To print using a thermal head, the above prepared inks 1-4, 7 and C-1 to
C-3, C-5 were placed into empty Lexmark ink cartridges, No. 15MO120, and
fitted into the ink station of a Lexmark Z51.RTM. printer. They were
printed on to receiving elements 1 and 2 with the results summarized in
Tables 2 to 4.
TABLE 2
Atmospheric Contaminants HID, Light Fastness Test
Test (% retained) (% retained)
Receiving 100% dot 75% dot 100% dot 75% dot
Ink Element coverage coverage coverage coverage
C-1 1 30% 33% 86% 84%
C-1 2 29% 32% 79% 75%
1 1 98% 95% 104% 101%
1 2 97% 97% 99% 102%
2 1 77% 76% 94% 93%
2 2 72% 70% 94% 89%
The above results show that on either receiving element, the inventive ink
compositions 1 and 2 show considerable improvements in the light fastness
and ozone fastness over that of the comparison ink composition.
TABLE 3
Atmospheric Contaminants HID, Light Fastness Test
Test (% retained) (% retained)
Receiving 100% dot 75% dot 100% dot 75% dot
Ink Element coverage coverage coverage coverage
C-1 1 21% 23% 75% 75%
C-1 2 28% 29% 70% 65%
C-2 1 28% 29% 69% 66%
C-2 2 24% 28% 56% 49%
C-3 1 45% 47% 84% 82%
C-3 2 46% 47% 82% 79%
3 1 92% 89% 98% 96%
3 2 94% 94% 100% 97%
4 1 91% 93% 99% 99%
4 2 93% 93% 98% 98%
The above results show that on either receiving element the inventive ink
compositions 3 and 4 show considerable improvements in the light fastness
and ozone fastness over that of the comparison ink compositions C-1, C-2
and C-3.
TABLE 4
Atmospheric Contaminants HID, Light Fastness Test
Test (% retained) (% retained)
Receiving 100% dot 75% dot 100% dot 75% dot
Ink Element coverage coverage coverage coverage
C-5 1 16% 17% 12% 15%
C-5 2 21% 23% 16% 20%
7 1 90% 91% 80% 81%
7 2 88% 88% 95% 94%
2.sup.nd Experi-
ment
C-5 1 16% 20% 18% 25%
C-5 2 19% 28% 23% 26%
7* 1 92% 93% 87% 88%
7* 2 95% 94% 87% 87%
*ink prepared as for 7) but with water replacing the triethanolamine
The above results show that on either receiving element, the inventive ink
composition 7, with or without triethanolamine, shows considerable
improvement in stability to fading by both light and by atmospheric
contaminants such as ozone over that of the comparison ink composition
C-5.
Printing of Test Images Using a Piezo Head
To print using a Piezo head, inks C-4, 5 and 6 were placed in empty ink
sachets, the remaining air was removed by bleeding and the sachets were
fitted into a bay of the Mutoh 4100.RTM. printer. The following results
were obtained:
TABLE 4
Atmospheric Contaminants HID, Light Fastness Test
Test (% retained) (% retained)
Receiving At Maximum At Den- At Maximum At Den-
Ink Element Density sity = 1 Density sity = 1
C-4 1 24% 23% 75% 71%
C-4 2 25% 25% 55% 55%
5 1 97% 92% 98% 99%
5 2 99% 98% 99% 99%
6 1 88% 91% 97% 97%
6 2 88% 88% 95% 94%
The above results show that the inventive inks are better than the
comparison ink for both light and ozone fastness.
Physical Nature of the Inventive Colorants in the Inks by Microscopy
Four thermal ink samples (1-3 and C-1 were analyzed by transmission
electron microscopy (TEM) in a JEM-2000FX.RTM. operating at either 200 or
100 kV accelerating voltage, and by optical microscopy (OM) at
magnifications up to 1000.times. in an Olympus BX30.RTM. microscope. For
direct microscopy examination of ink formulations, suitable samples were
prepared by spreading a small drop of the ink onto a carbon film supported
on 200 mesh aluminum TEM grid (SPI Inc., West Chester, Pa. 19381). The
complementary observation of ink written onto the receiving elements set
forth in the invention was performed using suitable cross-sectioned
samples, prepared by cryomicrotomy in a Reichert Ultracut S.RTM.
microtome, equipped with a Reichert FCS.RTM. cryo-temperature attachment
and a diamond knife. Small area composition analysis was carried out with
Energy Dispersive Spectroscopy (EDS) using a focused electron beam,
.about.20 nm in diameter. The method used follows the standard analysis
technique as outlined in published books (e.g. see "Principles of
Analytical Electron Microscopy", Chapters 4 and 5, Edit. D. C. Joy, A. D.
Romig, and J. I. Goldstein, Plenum Press, New York, 1989).
For ink 1, TEM analysis revealed the ink contained a non-uniform
microstructure consisting mostly of spherically shaped islands, and
occasionally, irregularly shaped facetted particulates. The former
exhibited uniform contrast in the TEM, indicating that they are amorphous
solids, and were found to have the range approximately between 10 and 20
nm. Further, these islands are found to comprise agglomerates of amorphous
colorant solids, and as such are larger than the individual colorant
particles. The facetted particulates showed black and white contrast
indicating crystalline characteristics, and they ranged from .about.40 to
100 nm. Both the islands and particulates were found to contain Ni and S
by EDS, consistent with the colorant composition. For ink written on
receiving element 1, TEM observations revealed a distinct layer of
colorant deposited at the surface. At 100% dot coverage using the Lexmark
Z51.RTM. printer, this layer thickness was approximately 0.1 .mu.m.+-.0.05
.mu.m. In a complimentary fashion, optical microscopy showed that the
colorant had not significantly penetrated into the receiving elements, but
instead is confined as a thin layer at the surface. Taken together, the
microstructure and composition data indicate that the ink contains a
nanoparticulate dispersion of amorphous and crystalline colorants. These
characteristics are distinctly different than those found for the
comparison ink composition C-1.
For ink 2, TEM results similar to those of 1 were found. The ink dispersion
consisted mostly of spherically shaped islands, and occasionally
irregularly shaped facetted particulates. The former exhibited uniform
contrast in the TEM, indicating their amorphous nature, and were found to
be approximately 10-20 nm in size. Further, these islands are found to
comprise agglomerates of amorphous colorant solids, and as such are larger
than the individual colorant particles. The latter showed black and white
contrast, indicating their crystalline matrix, and ranged in size from
approximately 40 to 100 nm. Both the islands and the particulates were
found to contain Ni, Cu and S, as analyzed by EDS, consistent with the
colorant composition. For ink written on receiving element 1, TEM
observations revealed a distinct layer of colorant deposited at the
surface. At 100% dot coverage using the Lexmark Z51.RTM. printer, this
layer thickness was approximately 0.1 .mu.m.+-.0.05 .mu.m. In a
complimentary fashion, optical microscopy showed that the colorant had not
significantly penetrated into the receiving elements, but instead is
confined as a thin layer at the surface. Taken together, the
microstructure and composition data indicate that the ink contains a
nanoparticulate dispersion of amorphous and crystalline colorants. These
characteristics are distinctly different than those found for the
comparison ink composition C-1.
For ink 3, TEM analysis revealed the ink to exhibit microstructural
characteristics similar to those of 1 and 2. It consisted of spherically
shaped solid islands, and irregularly shaped facetted particulates. The
former exhibited uniform contrast in the TEM, indicative of its amorphous
matrix, and was found to have sizes ranging from 10-20 nm. Further, these
islands are found to comprise agglomerates of amorphous colorant solids,
and as such are larger than the individual colorant particles. The latter
showed black and white contrast, indicative of its crystalline matrix, and
they ranged from approximately 40 to 100 nm. Both the islands and the
particulates were found to contain Cu and S, as analyzed by EDS,
consistent with its colorant composition. For ink written on receiving
element 1, TEM observations revealed a distinct layer of colorant
deposited at the surface. At 100% dot coverage using the Lexmark Z51.RTM.
printer, this layer thickness was approximately 0.1 .mu.m.+-.0.05 .mu.m.
In a complimentary fashion, optical microscopy showed that the colorant
had not significantly penetrated into the receiving elements, but instead
is confined as a thin layer at the surface. Taken together, the
microstructure and composition data indicate that the ink contains a
nanoparticulate dispersion of amorphous and crystalline colorants. These
characteristics are distinctly different than those found for the
comparison ink composition C-1.
For ink C-1, when it was spread out and dried on the carbon film, TEM data
showed the ink was uniform in morphology, with no discernible
microstructure feature. Under the optical microscope, this dried ink
exhibited a cyan color and formed a uniform film. When printed on
receiving elements 1 and 2, cross-section TEM data revealed no solid
deposit at the surface. Cross-section OM observations showed this colorant
had significantly penetrated into the receiving elements. These
observations are consistent with the characteristics of soluble dye-based
inks that can penetrate into the receiving elements after the ink
deposition process.
Physical Nature of the Inventive Colorants in the Inks by Centrifugation
Ink samples 3, 4, C-1 and C-3 were used to fill centrifuge tubes and were
subjected to centrifugation for 24 h, using a Beckman Ultra
Centrifuge.RTM. with conditions of 60,000 rpm at 20.degree. C. A 100 .mu.L
sample was taken from the top 5 mm of the centrifuge tube, before and
after centrifugation. These were diluted with deionized water using the
same dilution factor such that the range of absorbance seen when the
visible spectra of the samples taken before centrifugation was within the
range of the spectrometer. For each sample, the spectral absorbance
maximum between 400 nm and 700 nm was recorded before centrifugation
(D.sub.1) and compared to the absorbance at that wavelength after
centrifugation (D.sub.2). The ratio of these values D.sub.2 /D.sub.1
expressed as a percentage is an indicator of the proportion by weight of
the colorant in the ink that exists in solution. The value 100-(D.sub.2
/D.sub.1) % is then an indicator of the proportion by weight of the
colorant that is in particulate form. These results are given in Table 6
below.
TABLE 6
Colorant Ink 100-(D.sub.2 /D.sub.1) %
A 3 86%
B 4 83%
DB199 C-1 34%
Bayscript Cyan BA .TM. C-3 50%
A similar experiment was performed using inventive colorant composition 7
(made from colorant D, with no triethanolamine) and comparison C-5. The
results are shown in Table 7 below.
TABLE 7
Colorant Ink 100-(D.sub.2 /D.sub.1) %
D 7* 75%
Ex. 2 of U.S. C-5 21%
Pat. No. 6,152,968
ink prepared as for 7) but with water replacing the triethanolamine
The above results show that in the invention ink compositions, the
colorants exist predominantly as particles that are capable of
sedimentation when centrifuged, which is not the case for the comparison
ink compositions.
Although the invention has been described in detail with reference to
certain preferred embodiments for the purpose of illustration, it is to be
understood that variations and modifications can be made by those skilled
in the art without departing from the spirit and scope of the invention.
*
