Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Reexamination Certificate
2001-01-05
2004-09-21
Hess, Bruce H. (Department: 1774)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
C428S032240
Reexamination Certificate
active
06793860
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to methods for making media for aqueous ink-jet systems and more particularly to methods for making aqueous ink-jet recording media using hot-melt extrudable ink-receptive compositions. The invention also encompasses media made by such methods.
2. Brief Description of the Related Art
Today, ink-jet printing systems are easier to use and more cost effective than many other printing systems. Ink-jet printing systems are capable of producing high-quality, multicolored images and text for many applications. As a result, ink-jet printing has become more popular in home-office, commercial, textile, and packaging markets, where printing systems are needed. In an ink-jet printing process, liquid ink is squirted through very fine nozzles in a printer, and the resultant ink droplets form an image directly on a recording medium. Typically, the medium comprises a coated film or paper substrate. The quality of the final image or text is largely dependent on the composition of the ink-jet recording medium particularly the coating(s) and substrate.
Most inks used in ink-jet printing devices are aqueous-based inks containing water as their primary component. The aqueous-based inks contain molecular dyes or pigmented colorants. Small amounts of water-miscible solvents, such as glycols and glycol ethers, may also be present in the ink. The intended medium (e.g., paper or film) may be coated with an ink-receptive composition. During printing (imaging), dyes or colorants from the ink penetrate into the ink-receptive coating on the medium. Water and other solvents, if present, evaporate from the printed medium during drying of the medium. By the terms, “ink-receptive coating” (or “ink-receptive composition”), as used herein, it is meant a coating or composition that is capable of receiving (i.e., absorbing) aqueous-based inks. By the term, “aqueous ink-jet recording medium”, as used herein, it is meant a medium coated with a composition that is capable of receiving (i.e., absorbing) aqueous-based inks. In order to form high-quality, multicolored images having well-defined resolution and color fidelity, the ink-receptive compositions should have good water absorptivity and be fast drying.
As described in Sargeant et al., U.S. Pat. No. 5,700,582, water-soluble polymers such as poly(vinyl alcohol), cellulose ethers, cellulose esters, poly(vinyl pyrrolidone), gelatins, poly(vinyl acetate) starch, poly(acrylic acids), poly(ethylene oxide), proteins, hydroxypropyl cyclodextrin, poly(2-ethyl-2-oxazoline), alginates, water-soluble gums, and the like are typically used in coating compositions for ink-jet recording media.
However, many water-soluble polymers, such as high molecular weight polyvinyl pyrrolidone, polyvinyl alcohol, natural polymers, and gums, are not suitable for forming hot-melt extrudable compositions, because these materials tend to degrade and decompose at their melting point temperatures.
Hence, current methods for applying water-soluble polymers onto substrates involve dissolving the polymers and other additives in a carrier fluid to form a coating solution. Suitable carrier fluids may comprise organic solvents and/or water. The coating solution is then applied to the substrate by a number of coating methods, such as roller coating, wire-bar coating, dip coating, air-knife coating, curtain coating, slide coating, blade coating, doctor coating, and gravure coating. In some instances, the coating solution may be extruded as a solution using a slot-die.
The major disadvantage with using such conventional coating methods is that an active drying process is required to remove water or solvent from the coating after the coating has been applied to the substrate. Typically, these drying processes use thermal ovens, and there are a limited choice of substrates that can be conveniently dried in such ovens. Many substrates do not have adequate thermal resistance. These drying processes can also place the ink-jet media manufacturer at a competitive cost disadvantage. For example, the speed of a media manufacturing line is limited by the slow drying rate of the coatings. The cost problems are compounded when multiple coatings, requiring multiple drying steps, are applied to the media.
In contrast, hot-melt extrusion coating technology is a high speed process. Extrusion coating technology is conventionally used in the packaging industry. In such coating processes, hot-melt extrudable compositions that do not contain any organic solvents or water, are extruded onto a substrate. By employing various thermoplastic resins, such as polyolefins and ethylene copolymers, extrusion coatings can provide strength, moisture vapor barriers, oxygen barriers, gas permeability, abrasion resistance, flame retardancy, flexibility, and elasticity for packaging and other industrial products.
In the ink-jet printing industry, various film and paper substrates are used to manufacture ink-jet recording media. However, clay-coated papers are typically not preferred, since these papers tend to absorb the aqueous ink vehicle and cockle, i.e., develop an uneven bumpy surface. Rather, polyethylene-coated paper is typically used as the substrate because of its excellent dimensional stability, moisture resistance, surface smoothness, tear resistance and tendency not to cockle. The polyethylene coating acts as a barrier layer and is generally impermeable to the aqueous ink vehicle.
For ink-jet recording media applications, melt-extrusion coating technology may be used to form a polyethylene moisture barrier coating on the base paper. For example, Abe et al., U.S. Pat. No. 5,372,884 discloses an ink-jet recording sheet comprising a transparent or opaque support having an ink-receiving layer. In Example 1, a melt-extrusion coating of a polyethylene resin is described as being applied to both sides of a paper support. Then, the surface of the resin on the front side of the paper is described as then being subjected to corona discharge treatment and coated with a solution of an ink-receiving layer comprising polyvinyl alcohol by means of a curtain coater.
Kojima, U.S. Pat. No. 5,677,067 discloses an inkjet recording sheet comprising an ink-receiving layer on a support material. A polyolefin resin-coated paper is described as one example of a support material. The polyolefin resin-coated paper may be produced by a melt-extrusion coating method.
Kobayashi et al., U.S. Pat. No. 5,910,359 discloses an ink-jet recording sheet having a transparent support and a colorant-receptive layer. Example 16 describes forming a high density polyethylene layer on a base paper by melt extrusion.
Melt extrusion coating techniques may also be used for coating other materials onto substrates.
For example, Emslander et al., U.S. Pat. No. 5,721,086 discloses an image receptor medium comprising a substrate and an image reception layer. The image reception layer comprises an acid or acid/acrylate-modified ethylene vinyl acetate (EVA) polymeric resin. The modified EVA resin is preferably capable of being extruded or co-extruded into a substantially two-dimensional sheet and bonding without delamination to an adjacent substrate layer when the layers are co-extruded or laminated. The material for the substrate layer is preferably a resin capable of being extruded or co-extruded into a substantially two-dimensional film. Suitable materials are described as including polyester, polyolefin, polyamide, polycarbonate, polyurethane, polystyrene, acrylic, and polyvinyl chloride. The medium may have an optional inkjet layer on the outer surface of the image reception layer. In Example 4, a multi-layered film is described as being made using a blown film co-extrusion process. Ink-jet layers comprising bottom and top-coating solutions are described as being solution-coated onto the film using a notchbar coater.
Malhorta, U.S. Pat. No. 5,928,765 discloses recording sheets for use in an electrophotographic printing process (xerography). This process involves generating an electrostatic latent imag
Risen, Jr. William M.
Sargeant Steven J.
Song Jay C.
Xing Linlin
Arkwright Incorporated
Hess Bruce H.
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