Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1999-01-07
2001-07-17
Schwartz, Pamela R. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S213000, C428S328000, C428S329000, C428S331000
Reexamination Certificate
active
06261669
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink jet recording medium having two coating layers on a base substrate. The surface layer of the medium primarily comprises inorganic particulates and the underlayer of the medium primarily comprises polymeric materials. More particularly, this invention relates to an ink jet recording medium that performs well within a full environment range.
BACKGROUND OF THE INVENTION
Recently, ink jet printing technology has been used for presentation, graphic arts, engineering drawing and home office applications. The performance requirements for ink jet media used for these applications are quite stringent. The media have to provide fast drying, good color fidelity, high image resolution, and archivability. In addition, the media must perform at different environmental conditions and be capable of being produced at an acceptable cost.
There are many commercial products and proposed designs available in the field. Both inorganic materials and organic polymers have been used in these designs. For example, U.S. Pat. Nos. 5,264,275, 5,275,867, 5,104,730, 4,879,166, 4,780,356 proposed designs using porous particles such as pseudo-boehmite, and U.S. Pat. Nos. 4,503,111, 3,889,270, 4,592,951, 5,102,717, 3,870,549, 4,578,285, 5,101,218 and 5,141,599 proposed designs using organic polymers such as poly(vinyl pyrrolidone), poly(alkyl vinyl ether-maleic acid), a mixture of gelatin and starch, a water insoluble polymer containing a cationic resin, poly(ethylene oxide), and crosslinked poly(vinyl alcohol). Although some of these designs improved some properties, none of them meets all functional performance requirements of a commercial ink jet recording medium. More importantly, none of these designs perform satisfactorily in a full environment range, of from low to high relative humidities (RH). For example, prior known media using inorganic particulates cause ink migration at high humidity and poor handling properties, and prior known media using organic polymers did not reliably give good image resolution and often gave low optical density at low humidity. U.S. Pat. No. 5,264,275 discloses a composite consisting of both inorganic particulate and organic polymer layers. However, this design uses three coating layers on a surface of a base substrate, with the designed product containing two different inorganic particulate layers.
SUMMARY OF THE INVENTION
We have recently designed an ink jet recording medium that provides an optimal performance in terms of quality, functionality and cost. The present inventive medium does not require the presence of three coating layers on a surface of a base substrate. Instead, the present inventive media are only required to have an inorganic particulate surface layer and a polymeric underlayer on a given surface of a base substrate. The surface layer primarily comprises inorganic particulates and the underlayer primarily comprises polymeric materials. In this regard, the inorganic particulates in the surface layer provide good image resolution and high optical density, while the polymeric materials in the underlayer provide a reservoir for an ink vehicle. The underlayer also provides a dye-fixing function when dye-fixing materials such as polymeric quaternary ammonium salts are also present therein.
The ink jet recording media encompassed by the present invention are full range ink jet recording media that perform well within a wide range of humidities. For example, they perform well at both a low humidity (about 20% RH) and a high humidity (about 80% RH), as well as at humidities therebetween.
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the base substrate can be a transparent plastic, an opaque plastic, a translucent plastic or a paper. Suitable polymeric materials for use as the base substrate include polyester, cellulose esters, polystyrene, polypropylene, polyvinyl acetate, polycarbonate, and the like. A polyethylene terephthalate polyester film is a particularly preferred base substrate. Further, while almost any paper can also be used as the base substrate, clay coated papers are particularly preferred as base substrate papers.
The thickness of the base substrate is not particularly restricted but should generally be in the range of from about 2 to about 10 mils, preferably from about 3.0 to about 5.0 mils. The base substrate may be pretreated to enhance adhesion of the polymeric underlayer coating thereto.
The surface layer of the medium in present invention primarily comprises one or more inorganic particulates, in a total amount of from about 75 to about 100 wt %, preferably from about 80 to about 100 wt %, based on the total weight of solids in the surface layer. Although the particle size of the inorganic particulates is not specifically limited, for a transparent ink jet recording medium of the present invention the average particle size of the particulates should be smaller than about 1 micrometer, preferably smaller than about 0.5 micrometer.
The surface layer of the inventive medium may also contain a certain percentage of one or more polymeric materials as a polymeric binder, if so desired. In such an instance, the ratio of the inorganic particulates to the polymeric binder should be equal to or higher than about 3:1, and preferably equal to or higher than about 4:1, on a weight/weight basis.
Typical examples of inorganic particulates which may be used in the surface layer of the present inventive ink jet recording medium include silica, alumina, titanium oxide, alumina hydrate, pseudo-boehmite, zinc oxide, tin oxide, and silica-magnesia, bentonite, hectorite, mixtures thereof, and the like.
Typical examples of polymeric binders which may be used in the surface layer of the present inventive ink jet recording media are hydrophilic polymeric materials such as poly(vinyl alcohol), poly(vinyl pyrrolidone), gelatins, poly(vinyl acetate), poly(acyclic acids), poly(ethylene oxide), cellulose ethers, hydroxypropylcyclodextrin, poly (2-ethyl-2-oxazoline), proteins, water-soluble gums, poly(acrylamide), alginates, mixtures thereof, and the like. Also, copolymers having hydrophilic components can be used as the polymeric binders, if so desired.
The underlayer of the present inventive ink jet medium primarily comprises one or more polymeric materials, in a total amount of from about 60 to about 100 wt %, preferably from about 70 to about 100 wt %, based on the total weight of solids in the underlayer. At least one of the polymeric materials present in the underlayer should be a water-soluble or water-imbibing component. The water-imbibing component should absorb water but not be soluble in water. Exemplary of such water-imbibing or water-soluble components are poly (vinyl alcohol), poly (vinyl pyrrolidone), gelatin, poly (vinyl acetate), poly (acrylic acid), hydroxyethylcellulose, poly (ethylene oxide), hydroxypropylcellulose, poly (2-ethyl-2-oxazoline), proteins, carboxymethylcellulose, alginate, water-soluble gums, 2-hydroxyethyl acrylate, N-hydroxyethyl acrylamide, N-hydroxymethyl acrylamide, dimethylaminoethyl methacrylate, mixtures thereof, and the like. The water-soluble or water-imbibing component can be a component of a homopolymer, a copolymer or a polymer blend.
In order to achieve archivability, a polymeric quaternary ammonium salt may also be used in the underlayer of the present inventive ink jet recording mediums, if so desired. The polymeric quaternary ammonium salts used in the underlayer should preferably be: (1) of high molecular weight, and more preferably possess an average molecular weight larger than 10,000; (2) soluble in a selected organic solvent system (e.g., methyl ethyl ketone, toluene, isopropyl alcohol, mixtures thereof, and the like); and (3) compatible with the polymeric materials in the underlayer. Exemplary polymeric quaternary ammonium salts include those disclosed in U.S. Pat. No. 5,206,071, which is incorporated herein by reference in its entirety.
The thickness ratio of the surface layer to the underlayer has an impact on the medium's performanc
Atherton Dave
Huang Miaoling
Sargeant Steven J.
Sun Kang
Yang Sen
Arkwright Incorporated
Birch, Stewart, Kolasch and Birch LLP
Schwartz Pamela R.
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