Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2002-06-24
2003-05-06
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S206000
Reexamination Certificate
active
06558779
ABSTRACT:
DESCRIPTION
1. Field of the Invention
The present invention relates to an improved recording element for ink jet printing.
2. 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./Feb. 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. No. 3,739,393, U.S. Pat. No. 3,805,273 and U.S. Pat. No. 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.
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 water-fastness, light-fastness, 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. improves 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. No. 4,474,850, U.S. Pat. No. 4,547,405, U.S. Pat. No. 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 are gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, and various types of cellulose derivatives. These conventional binders are mentioned in numerous patent documents.
Since printing speeds are becoming ever faster the issue of fast ink droplet absorption is a crucial one. A first droplet must be absorbed into the interior of the receiver layer before a second one arrives at the same pixel. So, to improve this property there is a permanent need for better absorptive pigments.
The present invention extends the teachings on ink-absorptive pigments in ink jet recording media.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide an ink jet recording element with high ink absorptivity.
It is a further object of the present invention to provide an ink jet recording element with very fast drying characteristics.
SUMMARY OF THE INVENTION
The above mentioned objects are realised by providing an ink jet recording element comprising a support and an ink receiving layer containing a binder and Ca
3
(PO
4
)
2
pigment characterized in that said Ca
3
(PO
4
)
2
pigment consists substantially of the whitlockite crystal structure.
DETAILED DESCRIPTION OF THE INVENTION
The essence of the present invention is the fact that the pigment incorporated in the ink receiver layer is calcium phosphate (Ca
3
(PO
4
)
2
) substantially completely composed of the so-called whitlockite crystal structure, also called &bgr;-calcium triphosphate (&bgr;-CTP), which is a rhombohedral crystal structure. By “substantially” is meant that the great majority of the calcium phosphate present shows this crystal structure. Minor amounts of other crystal structures which also can deviate stoechiometrically from Ca
3
(PO
4
)
2
may be present, such as apatite, hydroxylapatite, monetite, etc. The nature of the crystal structure(s) present can be verified by means of X-ray diffraction XRD. The preparation o
Lingier Stefaan
Vanmaele Luc
AGFA-Gevaert
Guy Joseph T.
Kelly Cynthia H.
Nexsen Pruet Jacobs & Pollard LLC
Shewareged B.
LandOfFree
Ink jet recording element does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink jet recording element, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink jet recording element will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3014860