Compositions – Organic luminescent material containing compositions
Reexamination Certificate
2001-12-27
2004-02-24
Koslow, C. Melissa (Department: 1755)
Compositions
Organic luminescent material containing compositions
C252S30140R, C252S30140S, C252S30140F, C252S30140P, C252S30140H, C252S301500, C252S30160R, C252S30160P, C252S30160S, C252S30160F, C106S031150, C106S031320, C106S031640, C106S031920
Reexamination Certificate
active
06695980
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to imaging compositions that contain functional materials, more specifically, electroluminescent materials, more specifically, electroluminescent materials that are dissolved, dispersed and/or solubilized in a fluid that is in a compressed state. The compositions are used to create a high-resolution pattern or image onto a substrate for display applications.
BACKGROUND OF THE INVENTION
Ink jet recording or printing systems are commonly used to create high-resolution patterns on a substrate. In a typical ink jet recording or printing system, ink droplets are ejected from a nozzle towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a functional material or functional material, such as a dye or pigment or polymer, and a large amount of solvent. In conventional ink jet printing systems, the liquid ink droplets are ejected from the nozzle using pressure pulses generated by an oscillating piezoelectric crystal or by heating the nozzle to generate an ink droplet resulting from bubble formation or from ink phase change. The solvent, or carrier liquid, typically is made up of water, an organic material such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof. There can be many additives in the system aimed at preserving the pixel integrity upon deposition to the receiver. Such materials may be surfactants, humectants, biocides, rheology modifiers, sequestrants, pH adjusters, and penetrants among others. Such materials are necessary due to the high solvent loads in conventional ink formulations. More recently, the ink jet printing method has been used to make electroluminescent display devices.
U.S. Pat. No. 6,245,393 discloses a method of making a muticolor display device, comprising a transparent substrate, fluorescent dye deposited in a dye layer on to a substrate by ink jet printing. There is a problem with this invention in that the ink jet printing compositions, which contain fluorescent dyes have high solvent loads to be used in conventional ink jet printers.
There are alternate technologies that are available in prior art, that eliminate this problem by using gaseous propellants. For example, Peeters et al., in U.S. Pat. No. 6,116,718, disclose a print head for use in a marking apparatus in which a propellant gas is passed through a channel, the functional material is introduced controllably into the propellant stream to form a ballistic aerosol for propelling non-colloidal, solid or semi-solid particulate or a liquid, toward a receiver with sufficient kinetic energy to fuse the marking material to the receiver. There is a problem with this technology in that the functional material and propellant stream are two different entities and the propellant is used to impart kinetic energy to the functional material. This can cause functional material agglomeration leading to nozzle obstruction and poor control over functional material deposition. Another problem with this technology is that when the functional material is added into the propellant stream in the channel it forms a non-colloidal ballistic aerosol prior to exiting the print head. This non-colloidal ballistic aerosol, which is a combination of the functional material and the propellant, is not thermodynamically stable. As such, the functional material is prone to settling in the propellant stream, which in turn, can cause functional material agglomeration leading to nozzle obstruction and poor control over functional material deposition.
Technologies that use supercritical fluid solvents to create thin films are also known. For example, R. D. Smith in U.S. Pat. No. 4,734,227, issued Mar. 29, 1988, discloses a method of depositing solid films or creating fine powders through the dissolution of a solid material into a supercritical fluid solution and then rapidly expanding the solution to create particles of the functional material in the form of fine powders or long thin fibers which may be used to make films. There is a problem with this method in that the free-jet expansion of the supercritical fluid solution results in a non-collimated/defocused spray that cannot be used to create high-resolution patterns on a receiver. Further, defocusing leads to losses of the functional material.
A different approach for creating high resolution patterns is needed—one that would eliminate the issues with solvent management. There is also a need for a technology that permits high speed, accurate, and precise deposition of a functional material, more specifically, electroluminescent material on a substrate to create display devices. There is also a need for a technology that permits high speed, accurate, and precise patterning of a substrate that can be used to create high-resolution patterns on a receiver to form electroluminescent displays.
SUMMARY OF THE INVENTION
The present invention overcomes the problems discussed above by providing an imaging composition comprising a mixture of a fluid and a functional material, more specifically electroluminescent material. The fluid is compressed and the functional material is dissolved, dispersed and/or solubilized in the compressed fluid. The mixture is thermodynamically stable or thermodynamically metastable or both. The invention is useful for making organic light emitting diode and polymeric light emitting diode display applications.
DETAILED DESCRIPTION OF THE INVENTION
The formulations useful in the present invention contain a functional material, more specifically, electroluminescent material, which is dissolved, dispersed and/or solubilized, in a compressed fluid. The compressed fluid is any material with a density greater than 0.1 grams/cc. The compressed fluid may include a compressed liquid and/or a supercritical fluid. Materials that are at sufficiently high temperatures and pressures below their critical point are known as compressed liquids. Materials in their supercritical fluid and/or compressed liquid state that exist as gases at ambient conditions find application here because of their unique ability to dissolve, solubilize and/or disperse functional materials, more specifically, electroluminescent materials, of interest in the compressed liquid or supercritical state. In this context, the chosen materials taken to a compressed liquid and/or supercritical fluid state are gases at ambient pressure and temperature. Ambient conditions are preferably defined as temperature in the range from −100 to +100° C., and pressure in the range from 1×10
−8
-100 atm for this application. More commonly, the ambient conditions are temperature in the range of 0 to 100° C. and pressure in the range from 1×10
−5
to 100 atm. for this application. One skilled in the art should know how to select and maintain the appropriate ambient conditions such that the selected compressed fluid is gas at the ambient conditions.
The compressed fluids include, but are not limited to, carbon dioxide, nitrous oxide, ammonia, xenon, ethane, ethylene, propane, propylene, butane, isobutane, chlorotrifluoromethane, monofluoromethane, sulphur hexafluoride and mixtures thereof. Due its characteristics, e.g. low cost, wide availability, etc., carbon dioxide is generally preferred in many applications.
Functional materials, more specifically, electroluminescent materials can be any material that needs to be delivered to a receiver, to create a pattern on the receiver by deposition, or etching or other processes involving the placement of a functional material on a receiver for creating an electroluminescent device.
The functional materials, more specifically, electroluminescent materials may be selected from species that are ionic and/or molecular of the types such as organic, inorganic, metallo-organic, polymeric, oligomeric, metallic, alloy, ceramic, a synthetic and/or natural polymer, and a composite material of these previously mentioned. The functional material, more specifically, electroluminescent material can be a solid or a liqui
Irvin Glen C.
Jagannathan Ramesh
Jagannathan Seshadri
Mehta Rajesh V.
Sadasivan Sridhar
Eastman Kodak Company
Koslow C. Melissa
Wells Doreen M.
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