Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-06-21
2003-03-18
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S096000, C106S031600
Reexamination Certificate
active
06533408
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink jet printing method employing an ink composition containing water-dispersible polymers.
BACKGROUND OF THE INVENTION
Ink jet printing is a non-impact method for producing images by the deposition of ink droplets on a substrate (paper, transparent film, fabric, etc.) in response to digital signals. Ink jet printers have found broad applications across markets ranging from industrial labeling to short run printing to desktop document and pictorial imaging.
In ink jet recording processes, it is necessary that the inks being used meet various performance requirements. Such performance requirements are generally more stringent than those for other liquid ink applications, such as for writing instruments (e.g., a fountain pen, felt pen, etc.). In particular, the following conditions are generally required for inks utilized in ink jet printing processes:
(1) The ink should possess physical properties such as viscosity, surface tension, and electric conductivity matching the discharging conditions of the printing apparatus, such as the driving voltage and driving frequency of a piezoelectric electric oscillator, the form and material of printhead orifices, the diameter of orifices, etc;
(2) The ink should be capable of being stored for a long period of time without causing clogging of printhead orifices during use;
(3) The ink should be quickly fixable onto recording media, such as paper, film, etc., such that the outlines of the resulting ink dots are smooth and there is minimal blotting of the dotted ink;
(4) The printed image should be of high quality, such as having a clear color tone and high density, have high gloss and high color gamut;
(5) The printed image should exhibit excellent waterfastness (water resistance) and lightfastness (light resistance);
(6) The printed (ink) images should have good adhesion to the surface of image receiving elements and should be durable and highly resistant to physical and mechanical scratches or damages;
(7) The ink should not chemically attack, corrode or erode surrounding materials such as the ink storage container, printhead components, orifices, etc;
(8) The ink should not have an unpleasant odor and should not be toxic or inflammable; and
(9) The ink should exhibit low foaming and high pH stability characteristics.
The inks used in 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 cosolvents. 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 lightfastness. When water is used as the carrier medium, such inks also generally suffer from poor waterfastness.
Pigment-based inks have been gaining in popularity as a means of addressing these limitations. In pigment-based inks, the colorant exists as discrete particles. These pigment particles are usually treated with addenda known as dispersants or stabilizers which serve to keep the pigment particles from agglomerating and/or settling out.
Pigment-based inks suffer from a different set of deficiencies than dye-based inks. One deficiency is that pigment-based inks interact differently with specially coated papers and films, such as transparent films used for overhead projection and glossy papers and opaque white films used for high quality graphics and pictorial output. In particular, it has been observed that pigment-based inks produce imaged areas that are entirely on the surface of coated papers and films which results in images that have poor dry and wet adhesion properties and can be easily smudged. In recent years, inkjet receivers have been developed to have both high gloss and high porosity to give fast drying capabilities. However, scratch mark smudges are more visible on high gloss receivers. There is a need to provide a pigmented ink composition which can be used in printing images on the surface of an ink jet receiving element which have improved durability and smudging resistance.
Ozone is generally present in the air at sea level at a concentration of about 10 to 50 parts per billion. Only under certain conditions does the ozone concentration exceed these levels. However, even at low ozone concentrations, dyes and pigments such as ink jet dyes and pigments can be very sensitive and fade significantly when the air permeability is high, such as when they are printed onto porous, glossy receivers.
Although ink jet receivers designed for outdoor usage tend to have good durability when printed with pigmented inks, they also fade significantly due to their exposure to ozone caused by high air permeability.
U.S. Pat. No. 5,716,436 and JP 2000-290553 disclose the use of water-dispersible polymers in ink jet inks which are printed onto plain paper. However, images printed with these inks have low optical densities and very poor wet abrasion resistance and will not withstand outdoor applications.
GB 2 351 292 relates to an ink jet ink composition containing a water-dissipatable polymer comprising a reaction product. However, there is no disclosure in this patent of the use of these compositions on a receiver other than plain paper.
It is an object of this invention to provide an ink jet printing method using an ink jet ink composition containing water-dispersible polymers so that images printed on the surface of an ink jet receiving element using the ink composition will have improved ozonefastness and physical durability such as scratch and smudging resistance.
SUMMARY OF THE INVENTION
These and other objects are achieved in accordance with this invention which relates to an ink jet printing method, comprising the steps of:
A) providing an ink jet printer that is responsive to digital data signals;
B) loading the printer with an ink-receiving element comprising a support having thereon a continuous, coextensive, porous ink-receiving layer having interconnecting voids;
C) loading the printer with an ink jet ink composition comprising water, a humectant, a pigment and particles of a water-dispersible polymer; and
D) printing on the ink-receiving layer using the ink jet ink in response to the digital data signals.
The ink jet printing method of the invention using a porous receiver and an ink composition containing particles of a water-dispersible polymer provides images which have improved ozonefastness and physical durability such as scratch and smudging resistance.
DETAILED DESCRIPTION OF THE INVENTION
The support for the ink-receiving element employed in the invention can be paper or resin-coated paper, plastics such as a polyolefin type resin or 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, etc. or comprising an open pore structure such as those made from polyolefins or polyesters. 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.
In a preferred embodiment of the invention, the continuous, coextensive, porous ink-receiving layer contains organic or inorganic particles. Examples of organic particles which may be used include core/shell particles such as those disclosed in U.S Ser. No. 09/609/969 of Kapusniak et al., filed Jun. 30, 2000, and homogeneous particles such as those disclosed in U.S. Ser. No. 09/608/466 of Kapusniak et al., filed Jun. 30, 2000, the disclosures of which are hereby incorporated by reference. Examples of organic particles which may be used in
Campbell Bruce C.
Erdtmann David
Han-Adebekun Chris G.
Lopez Edgardo
Martin Thomas W.
Barlow John
Cole Harole E.
Eastman Kodak Company
Shah Manish S.
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