Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1999-07-30
2001-08-28
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S101000, C347S105000
Reexamination Certificate
active
06280028
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink jet printing process for improving the dye density and fixability of an ink jet image ink containing a water-soluble cationic or basic dye.
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. No. 5,560,996 relates to the use of a printing paper containing an intercalated compound that can chemically fix water soluble, cationic or anionic dyes to the paper by an electrostatic attraction between the dye and the intercalated compound. Although this type of an ink receiving layer does provide an image with good fixability, there is a problem with this material in that the overall density of the images generated is too low, as will be shown hereafter.
It is an object of this invention to provide an ink jet printing process for improving the fixability of an ink jet image so that it does not smear or wander when subjected to water for a period of time. It is another object of this invention to provide an ink jet printing process wherein the ink jet image is of high density.
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 dye density and fixability of an ink jet image comprising:
a) providing an ink jet recording element comprising a support having thereon an image-recording layer comprising a mixture of a hydrophilic polymer and a polyolefin polymer or wax; and
b) applying droplet s of a liquid ink on the image-recording layer in an image-wise manner, the ink comprising water, humectant and a water-soluble cationic or basic dye.
It was found that the fixability of the printed ink jet image is of high density and does not smear or wander when subjected to water for a period of time.
DETAILED DESCRIPTION OF THE INVENTION
A variety of basic or cationic dyes may be used in the invention as disclosed in U.S. Pat. No. 5,560,996, the disclosure of which is hereby incorporated by reference. In a preferred embodiment of the invention, the dye is an azo dye, a triphenylmethane dye, a phthalocyanine dye, an azine dye, an oxazine dye, a thiazine dye, each having an amine salt residue or a quaternary ammonium group. Such inks may be prepared directly from the basic or cationic dyes or by redissolving the leuco or deprotonated, electrically neutral forms (precursor) of these dyes in dilute aqueous acids, as described in U.S. Pat. Nos. 4,880,769; 3,992,140; and 5,559,076 and U.S. Ser. Nos. 09/299,480 and 09/299,412, both filed Apr. 26, 1999 the disclosures of which are hereby incorporated by reference. Examples of such electrically neutral forms of cationic dyes include the following:
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.
In a preferred embodiment of the invention, the polyolefin which may be employed is a dispersion of submicron size, e.g., from about 0.01 &mgr;m to 1 &mgr;m. The polyolefin may be an aqueous or non-aqueous dispersion such as polypropylene, polyethylene, high density polyethylene, oxidized polyethylene, ethylene-acrylic acid copolymers, etc.
The waxes which may be employed in the invention can be a microcrystalline wax, paraffin, or a natural wax such as carnauba wax, including aqueous dispersions of synthetic waxes. A dispersing aid such as polyethylene glycol may also be used.
In another preferred embodiment of the invention, the polyolefin employed preferably has a melting point (Tm) between about 25° C. and about 175° C. A plasticizer may also be added if desired.
Specific examples of polyolefins which may be used in the invention include the following:
TABLE 1
Polymer
Tm
Particle
No.
Polyolefin
Onset/Peak
Size nm
1
P-1
High Density Polyethylene
123/131
60
PE260 (Chemical Corporation of
America Inc.)
P-2
High Density Polyethylene
123/130
68
PE392LE30 (Chemical
(CH
3
OH)
Corporation of America Inc.)
P-3
Polyethylene PE40 (Chemical
65/86
—
Corporation of America Inc.)
P-4
High Density Polyethylene
125/132
87
PE316N30A (Chemical
Corporation of America Inc.)
P-5
High Density Polyethylene
124/131
50
PE325N35 (Chemical Corporation
of America Inc.)
P-6
Oxidized High Density
121/129
80
Polyethylene AC392
(Allied Signal Co.)
P-7
Polyethylene with 2-5% Acrylic
82/95
45
Acid ME02925 (Michelman Inc.)
P-8
Ethylene-Acrylic Acid Copolymer
36/43 and
30
ME4983R (Michelman Inc.)
71/80
1
measured in water unless otherwise noted.
The polyolefin or wax which may be employed in the invention may be used in an amount of from about 0.2 to about 26 g/m
2
, preferably from about 1 to about 16 g/m
2
.
Any hydrophilic polymer may be used in the invention. For example, there may be used gelatin or polymers having the following formula:
wherein:
R
1
represents hydrogen or an alkyl group having from about 1 to about 6 carbon atoms; and
R
2
represents hydroxyl, pyrrolidone, NHCOR
3
or CONH—R
3
, where R
3
represents an alkyl group having from about 1 to about 6 carbon atoms.
Examples of the above hydrophilic polymer 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
.
Examples of hydrophilic polymers which may be used in this invention include:
G-1: Type IV non-deionized bone gel, isoelectric point=5.0 (Eastman Chemical Co.)
G-2: Acid Processed Ossein gel, isoelectric point=6.7 (Croda Colloids Ltd.)
G-3: Pig skin deionized gel, isoelectric point=8.0 (SKW Biosystems).
In a preferred embodiment of the invention, the weight ratio of polyolefin or wax to hydrophilic polymer is from about 1:9 to about 8:2, preferably from about 1 to about 1.
The pH of the aqueous ink compositio
Evans Steven
Kovacs Csaba A.
Lawrence Kristine B.
Barlow John
Cole Harold E.
Eastman Kodak Company
Shah Manish S.
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