Ink jet printing process

Details Ink jet printing process Ink jet printing process

2001-03-21

2003-04-15

Klemanski, Helene (Department: 1755)

Compositions: coating or plastic

Coating or plastic compositions

Marking

C347S100000

Reexamination Certificate

active

06547865

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an ink jet printing process for improving the ozone 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 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.
The inks used in the various ink jet printers can be classified as either dye-based or pigment-based. A dye is a colorant which 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.
The ink jet receiving elements that can be used with the above mentioned inks must meet several requirements including producing high density images that will not smear, bleed or wander when exposed to water for short periods of time.
U.S. Pat. Nos. 6,149,722 and 6,015,896, WO 00/08103 and WO 98/49239 relate to inks containing phthalocyanine dyes used in ink jet printing. However, there is no disclosure in these references that these inks would be useful with a recording element containing a porous image-receiving layer.
It is an object of this invention to provide an ink jet printing process for improving the ozone stability of an ink jet image.
SUMMARY OF THE INVENTION
These and other objects are achieved in accordance with the present invention which comprises an ink jet printing process for improving the ozone stability of an ink jet image comprising:
a) providing an ink jet recording element comprising a support having thereon a porous image-receiving layer having interconnecting voids; and
b) applying droplets of a liquid ink on the image-receiving layer in an image-wise manner, the ink comprising water, humectant and a metallized, phthalocyanine dye, the metallized, phthalocyanine dye comprising the formula:
MPc(SO
3
X)
a
(SO
2
NRR′)
b
wherein:
M represents a metal; such as copper, nickel, aluminum, zinc, iron or cobalt.
Pc represents a phthalocyanine nucleus;
X represents hydrogen, alkali metal or an organic cation;
a is from 0 to 2;
R represents hydrogen; a substituted or unsubstituted alkyl group having from about 1 to about 15 carbon atoms, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group;
R′ represents an amino acid radical or at least one substituted or unsubstituted alkyl, aryl or heterocyclic substituent containing a primary, secondary, tertiary or quaternary amino group which may be part of a cyclic ring; and
b is from 1 to 4, with the proviso that a+b is an average of from 3 to 4.
It was found that the ozone stability of an ink jet image was improved using the compounds described herein.
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment of the invention, the metallized, phthalocyanine dyes which may be used include the following:
 MPc(SO
3
X)
a
(SO
2
NHR′)
b
(M is Cu, and X, Pc, a and b being defined as above)
TABLE 1
Dye
R′
1

2

3

4

5

6

7

8

9

10
 MPc(SO
3
X)
a
(SO
2
NHR′)
b
(M is Ni, and X, Pc, a and b being defined as above)
TABLE 2
Dye
R′
11

12
The dyes described above may be employed in any amount effective for the intended purpose. In general, good results have been obtained when the dye is present in an amount of from about 0.2 to about 5% by weight of the ink jet ink composition, preferably from about 0.3 to about 3% by weight. Dye mixtures may also be used.
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. 09/650,129, filed Aug. 29, 2000, polyethylene polymer-containing material sold by PPG Industries, Inc., Pittsburgh, Pennsylvania under the trade name of Teslin® Tyvek® synthetic paper (DuPont Corp.), and OPPalyte® 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 &mgr;m, preferably from about 75 to about 300 &mgr;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 porous ink-receptive layer contains inorganic particles such as silica, alumina, titanium dioxide, clay, calcium carbonate, barium sulfate, or zinc oxide. In another preferred embodiment, the porous ink-receptive layer comprises from about 30% to about 95% inorganic particles and from about 5% to about 70% polymeric binder, such as gelatin, poly(vinyl alcohol), poly(vinyl pyrrolidinone) or poly(vinyl acetate). The porous ink-receptive 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. The porous image-receiving layer comprises from about 10% to about 95% inorganic particles and from about 5% to about 90% of a polymeric binder.
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
2
, preferably from about 1 to about 16 g/m
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 7, 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.
A humectant is 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

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