Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Reexamination Certificate
1998-12-16
2001-02-06
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
C428S195100, C428S207000, C428S211100, C428S323000, C428S328000, C428S329000, C428S331000, C428S500000, C428S522000, C428S532000
Reexamination Certificate
active
06183844
ABSTRACT:
When substrates coated with an ink-receiving coating are printed with inkjet printing inks and dried, the inks often later migrate from their original locations on the coated substrate, thereby resulting in unsatisfactory images. Such migration is known as “bleed” or “bloom” and is especially prevalent under conditions of high temperature and high humidity such as for example, 35° C. and 80 percent relative humidity.
Low wet smear resistance is another problem that has arisen in inkjet printing. “Wet smear resistance” is the ability of inkjet printing to resist smearing when the inkjet printed and dried substrate is rubbed in the presence of water.
Printing media which may be inkjet printed to provide images of low bleed and/or improved wet smear resistance when used with a wide variety of inkjet printing inks, and printed media which provide images of low bleed and/or improved wet smear resistance, have now been found.
Accordingly a first embodiment of the invention is a printing medium comprising: (a) a substrate having at least one surface; (b) an interior water-absorptive coating on a surface of the substrate wherein the interior water-absorptive coating comprises: (1) a matrix of hydrophilic organic polymer which contains from 10 to 50 percent by weight nitrogen-containing substance, and (2) discrete nonfilm-forming particles which have a number average particle size in the range of from 1 to 500 nanometers and which are distributed throughout the matrix of the interior water-absorptive coating; and (c) an exterior water-absorptive coating on the interior water-absorptive coating wherein the exterior water-absorptive coating comprises: (1) a matrix of hydrophilic organic polymer which contains from 0 to 30 percent by weight nitrogen-containing substance, and (2) discrete nonfilm-forming particles which have a number average particle size in the range of from 1 to 500 nanometers and which are distributed throughout the matrix of the exterior water-absorptive coating; wherein: (d) each nitrogen-containing substance is independently selected from the group consisting of quaternary ammonium mer units, poly(N-vinylpyrrolidinone), copolymer of N-vinylpyrrolidinone and &agr;-(meth)acrylyloxy-&ohgr;-(hydroxy, methoxy, or ethoxy)-poly(ethylene oxide), and two or more thereof; and (e) the hydrophilic organic polymer of the interior water-absorptive coating contains a greater quantity of nitrogen-containing substance than the hydrophilic organic polymer of the exterior water-absorptive coating, on a percent by weight basis.
The interior water-absorptive coating and the exterior water-absorptive coating both comprise hydrophilic organic polymer. The main difference is that the hydrophilic organic polymer of the interior water-absorptive coating contains more nitrogen-containing substance than the hydrophilic organic polymer of the exterior water-absorptive coating. Usually, but not necessarily, the difference between the quantity of nitrogen-containing substance of the hydrophilic organic polymer of the interior coating expressed as percent by weight and the quantity of nitrogen-containing substance of the hydrophilic organic polymer of the exterior coating expressed as percent by weight, is at least 0.1 percent. Often the difference is at least 1 percent. In many cases the difference is at least 5 percent. Preferably the difference is at least 10 percent. These differences are formed by simple subtraction of the two percentages.
In the interests of brevity, the coating composition used to form the interior water-absorptive coating will be referred to as the “interior coating composition” and the coating composition used to form the exterior water-absorptive coating will be referred to as the “exterior coating composition”.
The printing media of the invention may be made by coating a surface of a substrate with an interior coating composition to form an interior coating, and coating the interior coating with an exterior coating composition to form an exterior coating. Volatile aqueous liquid may be partially or wholly removed from the interior coating prior to coating with the exterior coating composition. Alternatively, the exterior coating composition may be applied to the interior coating before removing volatile aqueous liquid; volatile aqueous liquid is then substantially removed after application of the exterior coating composition.
The substrate may be any substrate at least one surface of which is capable of bearing the coating discussed above. In most instances the substrate is in the form of an individual sheet or in the form of a roll, web, strip, film, or foil of material capable of being cut into sheets. It may be an uncoated material or it may be the exposed coating of a material which has been previously coated with one or more coatings.
The substrate may be porous throughout, it may be nonporous throughout, or it may comprise both porous regions and nonporous regions.
Examples of porous substrates include paper, paperboard, wood, cloth, nonwoven fabric, felt, unglazed ceramic material, polymer membranes, porous foam, and microporous foam.
Examples of substrates which are substantially nonporous throughout include sheets or films of organic polymer such as poly(ethylene terephthalate), polyethylene, polypropylene, cellulose acetate, poly(vinyl chloride), and copolymers such as saran. The sheets or films may be metallized or unmetallized as desired. Additional examples include metal substrates including but not limited to metal foils such as aluminum foil and copper foil. Yet another example is a porous or microporous foam comprising thermoplastic organic polymer which foam has been compressed to such an extent that the resulting deformed material is substantially nonporous. Still another example is glass.
Base stocks which are normally porous such as for example paper, paperboard, wood, cloth, nonwoven fabric, felt, unglazed ceramic material, polymer membranes, porous foam, or microporous foam may be coated or laminated to render one or more surfaces substantially nonporous and thereby provide substrates having at least one substantially nonporous surface.
The substrate may be substantially transparent, it may be substantially opaque, or it may be of intermediate transparency. For some applications such as inkjet printed overhead slides, the substrate must be sufficiently transparent to be useful for that application. For other applications such as inkjet printed paper, transparency of the substrate is not so important.
Each of the coating compositions used to produce the printing media of the invention can independently be in the form of an aqueous solution in which case the volatile aqueous liquid is a volatile aqueous solvent for the film-forming organic polymer of the coating composition, or the coating composition can be in the form of an aqueous dispersion in which instance the volatile aqueous liquid is a volatile aqueous dispersion liquid for at least some of the film-forming organic polymer of the coating composition.
The volatile aqueous liquid is predominately water. Small amounts of low boiling volatile water-miscible organic liquids may be intentionally added for particular purposes. Examples of such low boiling volatile water-miscible organic liquids solvents include methanol [CAS 67-56-1], ethanol [CAS 64-17-5], 1-propanol, [CAS 71-23-8], 2-propanol [CAS 67-63-0], 2-butanol [CAS 78-92-2], 2-methyl-2-propanol [CAS 75-65-0], 2-propanone [CAS 67-64-1], and 2-butanone [CAS 78-93-3]. The listing of such liquids is by no means exhaustive.
Similarly, water-miscible organic liquids which themselves are of low, moderate, or even negligible volatility may be intentionally added for particular purposes, such as for example, retardation of evaporation. Examples of such organic liquids include 2-methyl-1-propanol [CAS 78-83-1], 1-butanol [CAS 71-36-3], 1,2-ethanediol [CAS 107-21-1], and 1,2,3-propanetriol [CAS 56-81-5]. The listing of such liquids
Grendzynski Michael E.
Hess Bruce H.
Hewlett--Packard Company
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