Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2001-11-29
2003-10-21
Nguyen, Judy (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C347S105000, C428S195100
Reexamination Certificate
active
06634743
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for increasing the diameter of an ink jet ink dot.
BACKGROUND OF THE INVENTION
In a typical ink jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye or pigment, and a large amount of solvent. The solvent, or carrier liquid, typically is made up of water and an organic material such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof.
An inkjet recording element typically comprises a support having on at least one surface thereof an ink-receiving or image-receiving layer, and includes those intended for reflection viewing, which have an opaque support, and those intended for viewing by transmitted light, which have a transparent support.
An important characteristic of ink jet recording elements is their need to dry quickly after printing. To this end, porous recording elements have been developed which provide nearly instantaneous drying as long as they have sufficient thickness and pore volume to effectively contain the liquid ink. For example, a porous recording element can be manufactured by cast coating, in which a particulate-containing coating is applied to a support and is dried in contact with a polished smooth surface.
When an ink drop contacts the ink jet recording medium, the drop initially spreads on the surface and then begins to adsorb into the medium. The ink adsorbs vertically into the medium as well as radially. The rate of ink adsorption depends on the nature of the medium. Ink adsorption in non-porous media comprising hydrophilic polymers takes place due to molecular diffusion and occurs at a much slower rate than for porous media where the ink adsorption occurs due to capillary action. The adsorption of the ink drop transports a colorant into the medium to form the image.
The diameter of the resulting colorant in the medium is referred to as dot size. Dot size is an important parameter in ink jet printing systems and is a key component in establishing image quality and printer productivity. Smaller dot sizes yield a gain in edge acuity but decrease printer productivity. Larger dot sizes can cover up for printing errors due to misplaced drops. Therefore, the ability to control dot size is an important issue for ink jet printing systems.
Dot gain refers to the increase in dot size over the initial, spherical drop diameter. The dot gain is determined by the ratio of the final dot diameter to the initial drop diameter. The desired dot size is typically achieved by controlling the drop volume, i.e., larger volume drops produce larger dot sizes in the medium. It would be desirable to find a way to increase dot size without having to increase drop volume.
U.S. Pat. No. 6,114,022 relates to a method for controlling the dot diameter on an ink jet receptive medium that employs a microporous medium and a porous imaging layer. The dot gain achieved by this process is about 3.5. However, there are problems with this method in that the amount of dot gain is not as large as one would like and the process is limited to pigmented inks.
It is an object of this invention to provide a method for increasing the dot gain of an ink jet ink drop applied to an ink jet recording element in an amount of up to about 10. It is another object of the invention to provide a method for increasing the diameter of an ink jet ink dot resulting from the application of an ink jet ink drop wherein the ink jet ink comprises a dye.
SUMMARY OF THE INVENTION
These and other objects are achieved in accordance with the invention which comprises a method for increasing the diameter of an ink jet ink dot resulting from the application of an ink jet ink drop applied to the surface of an ink jet recording medium comprising a support having thereon an image-receiving layer and an overcoat layer, the ink penetration rate of the overcoat layer being faster than the ink penetration rate of the image-receiving layer; comprising the steps of:
a) applying the overcoat layer on top of the image-receiving layer at a thickness less than the maximum thickness, the maximum thickness being that thickness whereby an ink jet ink drop applied to the surface of the overcoat layer will not substantially penetrate the surface of the image-receiving layer; and
b) applying the inkjet ink drop on the surface of the overcoat layer whereby the diameter of the ink jet ink dot is increased relative to that which would have been obtained if the overcoat layer had been coated at a thickness of at least the maximum thickness.
By use of the method of the invention, the dot gain of an ink jet ink drop applied to an ink jet recording element can be in an amount of up to about 10 and the ink jet ink can comprise a dye.
Another advantage of the invention is that smaller volume of ink jet ink drops can be used to achieve dot sizes equivalent to those obtained with larger volume drops. This results in increased printer productivity since fewer dots are needed to cover an area of the recording medium, and the drying times are faster.
DETAILED DESCRIPTION OF THE INVENTION
The support for the ink jet recording medium used in the invention can be any of those usually used for ink jet receivers, such as resin-coated paper, paper, polyesters, or microporous materials such as polyethylene polymer-containing material sold by PPG Industries, Inc., Pittsburgh, Pa. under the trade name of Teslin®, Tyvek® synthetic paper (DuPont Corp.), and OPPalyte® films (Mobil Chemical Co.) and other composite films listed in U.S. Pat. No. 5,244,861. Opaque supports include plain paper, coated paper, synthetic paper, photographic paper support, melt-extrusion-coated paper, and laminated paper, such as biaxially oriented support laminates. Biaxially oriented support laminates are described in U.S. Pat. Nos. 5,853,965; 5,866,282; 5,874,205; 5,888,643; 5,888,681; 5,888,683;and 5,888,714, the disclosures of which are hereby incorporated by reference. These biaxially oriented supports include a paper base and a biaxially oriented polyolefin sheet, typically polypropylene, laminated to one or both sides of the paper base. Transparent supports include glass, cellulose derivatives, e.g., a cellulose ester, cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate; polyesters, such as poly(ethylene terephthalate), poly(ethylene naphthalate), poly(1,4-cyclohexanedimethylene terephthalate), poly(butylene terephthalate), and copolymers thereof; polyimides; polyamides; polycarbonates; polystyrene; polyolefins, such as polyethylene or polypropylene; polysulfones; polyacrylates; polyetherimides; and mixtures thereof. The papers listed above include a broad range of papers, from high end papers, such as photographic paper to low end papers, such as newsprint. In a preferred embodiment, polyethylene-coated paper is employed.
The support used in the invention may have a thickness of from about 50 to about 500 &mgr;m, preferably from about 75 to 300 &mgr;m. Antioxidants, antistatic agents, plasticizers and other known additives may be incorporated into the support, if desired.
In order to improve the adhesion of the ink-receiving layer to the support, the surface of the support may be subjected to a corona-discharge treatment prior to applying the image-receiving layer.
The image-receiving layer which may be used in the invention can either be porous or non-porous. If the image receiving layer is porous, it would comprise organic or inorganic particles dispersed in a polymeric binder. In a preferred embodiment of the invention, the polymeric binder is a hydrophilic polymer such as poly(vinyl alcohol), poly(vinyl pyrrolidone), gelatin, cellulose ethers, poly(oxazolines), poly(vinylacetamides), partially hydrolyzed poly(vinyl acetate/vinyl alcohol), poly(acrylic acid), poly(acrylamide), poly(alkylene oxide), sulfonated or phosphated polyesters and polystyrenes, casein, zein
Ng Kam C.
Perchak Dennis R.
Yip Kwok L.
Cole Harold E.
Eastman Kodak Company
Nguyen Judy
Shah Manish
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