Stock material or miscellaneous articles – Ink jet stock for printing – Specified property of backing layer
Reexamination Certificate
2002-03-04
2004-11-30
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Specified property of backing layer
C428S032240, C428S032260, C428S032270, C428S032280
Reexamination Certificate
active
06824841
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a particular type of ink jet recording material and its use in printing applications.
BACKGROUND OF THE INVENTION
In the majority of applications printing proceeds by pressure contact of an ink-loaden printing form with an ink-receiving material which is usually plain paper. The most frequently used impact printing technique is known as lithographic printing based on the selective acceptance of oleophilic ink on a suitable receptor.
In recent times however so-called non-impact printing systems have replaced classical pressure-contact printing to some extent for specific applications. A survey is given e.g. in the book “Principles of Non Impact Printing” by Jerome L. Johnson (1986), Palatino Press, Irvine, Calif. 92715, USA.
Among non-impact printing techniques ink jet printing has become a popular technique because of its simplicity, convenience and low cost. Especially in those instances where a limited edition of the printed matter is needed ink jet printing has become a technology of choice. A recent survey on progress and trends in ink jet printing technology is given by Hue P. Le in
Journal of Imaging Science and Technology
Vol. 42 (1), Jan/Febr 1998.
In ink jet printing tiny drops of ink fluid are projected directly onto an ink receptor surface without physical contact between the printing device and the receptor. The printing device stores the printing data electronically and controls a mechanism for ejecting the drops image-wise. Printing is accomplished by moving the print head across the paper or vice versa. Early patents on ink jet printers include U.S. Pat. Nos. 3,739,393, 3,805,273 and 3,891,121.
The jetting of the ink droplets can be performed in several different ways. In a first type of process a continuous droplet stream is created by applying a pressure wave pattern. This process is known as continuous ink jet printing. In a first embodiment the droplet stream is divided into droplets that are electrostatically charged, deflected and recollected, and into droplets that remain uncharged, continue their way undeflected, and form the image. Alternatively, the charged deflected stream forms the image and the uncharged undeflected jet is recollected. In this variant of continuous ink jet printing several jets are deflected to a different degree and thus record the image (multideflection system)
According to a second process the ink droplets can be created “on demand” (“DOD” or “drop on demand” method) whereby the printing device ejects the droplets only when they are used in imaging on a receiver thereby avoiding the complexity of drop charging, deflection hardware, and ink recollection. In drop-on-demand the ink droplet can be formed by means of a pressure wave created by a mechanical motion of a piezoelectric transducer (so-called “piezo method”), or by means of discrete thermal pushes (so-called “bubble jet” method, or “thermal jet” method).
Ink compositions for ink jet typically include following ingredients dyes or pigments, water and/or organic solvents, humectants such as glycols, detergents, thickeners, polymeric binders, preservatives, etc. It will be readily understood that the optimal composition of such an ink is dependent on the ink jetting method used and on the nature of the substrate to be printed. The ink compositions can be roughly divided in:
water based; the drying mechanism involves absorption, penetration and evaporation;
oil based; the drying involves absorption and penetration;
solvent based; the drying mechanism involves primarely evaporation;
hot melt or phase change: the ink vehicle is liquid at the ejection temperature but solid at room temperature; drying is replaced by solidification;
UV-curable; drying is replaced by polymerization.
It is known that the ink-receiving layers in ink-jet recording elements must meet different stringent requirements:
The ink-receiving layer should have a high ink absorbing capacity, so that the dots will not flow out and will not be expanded more than is necessary to obtain a high optical density.
The ink-receiving layer should have a high ink absorbing speed (short ink drying time) so that the ink droplets will not feather if smeared immediately after applying.
The ink dots that are applied to the ink-receiving layer should be substantially round in shape and smooth at their peripheries. The dot diameter must be constant and accurately controlled.
The receiving layer must be readily wetted so that there is no “puddling”, i.e. coalescence of adjacent ink dots, and an earlier absorbed ink drop should not show any “bleeding”, i.e. overlap with neighbouring or later placed dots, or non-printed areas.
Transparent ink-jet recording elements must have a low haze-value and be excellent in transmittance properties.
After being printed the image must have a good resistance regarding waterfastness, lightfastness, and good endurance under severe conditions of temperature and humidity.
The ink jet recording element may not show any curl or sticky behaviour if stacked before or after being printed.
The ink jet recording element must be able to move smoothly through different types of printers.
All these properties are often in a relation of trade-off. It is difficult to satisfy them all at the same time.
It is known that the presence in the ink accepting layer of absorptive pigments such as silica, kaolin, talc, aluminum oxide, boehmite, etc. improve the absorption capacity, the obtainable colour density and the drying time. Many patent applications have described this effect for many different binder-systems. U.S. Pat. No. 3,357,846 describes pigments such as kaolin, talc, bariet, TiO
2
used in starch and PVA. U.S. Pat. No. 3,889,270 describes silica in gelatin, PVA and cellulose. Pigments and particles have also been described in patent applications including DE 2,925,769, GB 2,050,866, U.S. Pat. Nos. 4,474,850, 4,547,405, 4,578,285, WO 88 06532, U.S. Pat. No. 4,849,286, EP 339604, EP 400681, EP 407881, EP 411638 and U.S. Pat. No. 5,045,864 (non-exhaustive list).
These particulates are dispersed in various types of binders of which the most common types such as gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, and various types of cellulose derivatives. These conventional binders are mentioned in numerous patent documents.
It is further known to use various types of film-forming polymers to improve the waterfastness of the coated ink receiving layer by increasing its adhesion to the support.
It is also known to improve the waterfastness of the finished printed image by the incorporation of cationic pigments or mordanting polymers bearing cationic quaternary groups such as ammonium-, sulphonium and phosphonium groups. These polymers interact with most typical ink jet inks resulting in a better anchoring of the dye in the binder. Typical examples of such descriptions are U.S. Pat. Nos. 4,371,582, 4,575,465, 4,649,064, GB 2 210 071 and EP 423829.
Many of the described or commercialy available ink jet recording materials suffer from one or more of the following deficiencies
sticking of front side to back side of the freshly manufactured ink jet recording element when rolled up as a web or, or when stacked after being cut in formats;
attraction of dust of the ink jet printed material when it is used as a master for the exposure of a printing plate such as an offset plate or a silk screen, or of a contact duplicating film; this is due to triboelectric differences;
insufficient sharpness of the printed dots;
insufficient resistance to feathering;
transport problems during printing;
a lack of sufficient density of full areas of the printed image;
migration of ink from the printed side to the back side during occasional rolling up of the film during printing;
lack of dimensional stability. This property is of extreme importance when the printed images emanate from digitally stored information corresponding to more then one colour selection, and the printed images are to be used as masters.
OBJECTS OF THE INVENTION
It is an object of the present invention to provid
Aert Huub Van
De Voeght Frank
Slabbinck Peter
AGFA-Gevaert
Guy Joseph T.
Kelly Cynthia H.
Nexsen Pruet , LLC
Shewareged B.
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