Ink jet ink composition

Details Ink jet ink composition Ink jet ink composition

2000-08-22

2003-03-18

Jagannathan, Vasu (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S091000, C524S092000, C524S094000, C524S106000, C524S190000

Reexamination Certificate

active

06534566

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATIONS
Reference is made to commonly assigned, co-pending U.S. Patent Application Serial Numbers:
Ser. No. 09/643,281 by Shuttleworth et al., filed of even date herewith, entitled “Ink Jet Ink Composition”;
Ser. No. 09/643,789 Shuttleworth et al., filed of even date herewith, entitled “Ink Jet Printing Method”; now U.S. Pat. No. 6,419,354;
Ser. No. 09/643,532 by Chen et al., filed of even date herewith, entitled “Ink Jet Printing Method”;
the disclosures of which are hereby incorporated by reference.
FIELD OF THE INVENTION
This invention relates to an ink jet ink composition containing cationic dyes and a polymer latex.
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 which 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.
Commercial dye based inks are commonly composed of a chromophoric unit which has attached to it, by some means, an anionic functionality. The receiver material commonly possesses some kind of cationic functionality, so that the integrity of the image is maintained by means of a salt type link, between the dye and receiver material as described in EP 970819A2. Much less common is the reverse of this system where the dye is cationic and the receiver contains the anionic function as described in EP1010539A1. There are always limitations for the above two scenarios that the right dye-mordant combination has to be chosen in order to obtain high quality inkjet prints with good waterfastness and light fastness.
U.S. Pat. No. 5,560,996 discloses a variety of cationic dyes, including cationic azo dyes such as Basic Red 46 and other cationic magenta dyes such as Basic Reds 12, 14 and 15 for use in an ink jet ink. However, there is a problem with these dyes in that they have poor light stability.
It is an object of this invention to provide an ink composition that is capable of yielding print images with consistent light fastness irrespective of the receiver type.
SUMMARY OF THE INVENTION
This and other objects are achieved in accordance with this invention which relates to an ink jet ink composition comprising water, a humectant, and a water-dispersible polymeric latex having contained therein a delocalized cationic azo dye derived from the quaternization of a nitrogen heterocyclic azo dye having the following formula:
wherein:
Z represents the atoms necessary to complete a nitrogen-containing heterocyclic ring containing 2 or 3 nitrogen atoms and the balance carbon atoms;
R
1
and R
2
each independently represents hydrogen or a substituted or unsubstituted alkyl group of 1 to about 6 carbon atoms;
R
4
, R
5
and R
6
each independently represents the same substituents as R
1
and R
2
, halogen, cyano, substituted or unsubstituted alkoxy, acyl, benzoyl or alkoxycarbonyl; with the proviso that at least one of R
4
, R
5
and R
6
represents a substituted or unsubstituted alkyl group of 1 to about 6 carbon atoms attached to a nitrogen atom;
R
3
represents the same groups as R
4
, R
5
and R
6
; hydroxy; a polyoxyalkylene group of 2-20 alkylene oxide residues; carboxy or sulfo or phospho ester; carbamoyl; substituted or unsubstituted alkyl-, aryl- aralkyl-, diaryl- or dialkyl-carbamoyl of 1 to about 20 carbon atoms; sulfamoyl; substituted or unsubstituted alkyl-, aryl-, aralkyl-, diaryl- or dialkyl-sulfamoyl of 1 to about 20 carbon atoms; acylamino; sulfonylamino; amino; a substituted or unsubstituted alkyl-, aryl-, aralkyl-, diaryl- or dialkylamino-of 1 to about 20 carbon atoms; or a quaternary ammonium or phosphonium group; or may be combined with R
2
to form a carbocyclic or heterocyclic 5 or 6 membered ring;
n is 1 except when Z represents the atoms necessary to complete a nitrogen-containing heterocyclic ring containing 3 nitrogen atoms, in which case n is 0; and
X represents a counterion;
with the proviso that when Z represents the atoms necessary to complete a nitrogen-containing heterocyclic ring of 3 nitrogen atoms, then R
3
is combined with R
2
to form a carbocyclic or heterocyclic 5 or 6 membered ring.
It has been found that these dyes provide excellent light stability for the printed image on a variety of different ink jet receivers when a water dispersible polymer latex is contained in the ink composition irrespective of the receiver type.
DETAILED DESCRIPTION OF THE INVENTION
Quaternized nitrogen heterocyclic-azo dyes are not new. They have been used for dyeing fabrics, particularly polyacrylonitrile fabrics. Typical examples are quaternized pyrazole-azo, imidazole-azo, triazole-azo dyes. Their use has been described for this purpose in “Chemistry and Application of Dyes” ed D. R. Waring and G. Hallas, (Plenum Press), p184. A typical preparation of dyes of this type is also described in the above reference (p197).
Representative examples of dyes employed in the invention are:

Dye
R
1
R
2
—R
3
R
4
R
5
&lgr;-max (nm)
1
n-C
4
H
9
2,2,4,7-Tetramethyl
CH
3
CH
3
547
tetrahydroquinoline
2
—H
2,2,4,7-Tetramethyl
CH
3
CH
3
534
tetrahydroquinoline
3
n-C
4
H
9
2,2,4,7-Tetramethyl
C
2
H
5
C
2
H
5
549
tetrahydroquinoline
4
C
2
H
5
2-Methyl-
CH
3
CH
3
546
benzoxazine
5
C
2
H
4
OH
2,2,4-Trimethyl
CH
3
CH
3
544
tetrahydroquinoline

Dye
R
1
R
2
R
3
R
4
R
5
R
6
&lgr; max
6
n-C
4
H
9
2,2,4,7-Tetramethyl
CH
3
CH
3
CONH(C
2
H
4
OH)
2
551
tetrahydroquinoline
7
C
2
H
4
Cl
2,2,4,7-Tetramethyl
CH
3
CH
3
CO
2
CH
3
530
tetrahydroquinoline
8
C
2
H
5
2,2,4-Trimethyl
CH
3
CH
3
CONHC
4
H
9
550
tetrahydroquinoline
9
C
2
H
5
C
2
H
5
H
CH
3
CH
3
CN
550
10
n-C
4
H
9
2,2,4,7-Tetramethyl
CH
3
CH
3
CO
2
CH
3
546
tetrahydroquinoline
11
n-C
3
H
7
n-C
3
H
7
3-NHCOCH
3
CH
3
CH
3
CO
2
CH
3
544
12
C
2
H
5
C
2
H
5
3-CH
3
CH
3
CH
3
CN
554
In a preferred embodiment of the invention, R
1
in the above formula represents hydrogen. In another preferred embodiment, R
2
represents C
4
H
9
. In still another preferred embodiment, R
2
and R
3
are taken together and represent a tetrahydroquinoline ring. In yet another preferred embodiment, R
4
represents CN or CON(C
2
H
4
OH)
2
. In still another preferred embodiment, R
5
and R
6
each represents CH
3
.
In general, the above dyes comprise from about 0.2 to about 5%, preferably from about 0.5 to 3%, by weight of the ink jet composition.
The cationic dyes of the present invention should be practically water insoluble, with the solubility in water preferably less than about 0.1 g/l at 25° C., and the solubility in organic solvents such as methanol, acetone, ethyl acetate tetrahydrofuran greater than or equal to about 0.2 g/l. The solubility of cationic dyes in water and organic solvent is significantly affected by the nature of the counterion X
−
. The counterions preferred for solubility are BF
4
−
, OTs
−
, PF
6
−
, C
12
H
25
SO
3
−
and ClO
4
−
.
The dye-containing polymeric latex employed in the invention can be prepared by dissolving the dye in a water-miscible organic solvent, mixing the solution with the latex and then removing the solvent. Useful water-miscible organic solvents are water-miscible alcohols, ketones and amides, tetrahydrofuran, N-methyl-2-pyrrolidone, dimethylsulfoxide and mixtures thereof, such as acetone, ethy

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