Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-10-11
2002-01-22
Jagannathan, Vasu (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S513000, C524S521000, C525S217000, C525S228000
Reexamination Certificate
active
06340725
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. an 80 percent relative humidity.
It has now been found that bleed can be substantially reduced or even eliminated if the coating contains organic polymer which is substantially free of ammonium groups, addition polymer containing quaternary ammonium groups, and addition polymer containing secondary, tertiary, or both secondary and tertiary ammonium groups.
Accordingly, one embodiment of the invention is a coating composition comprising: (a) a volatile aqueous liquid medium; and (b) binder dissolved or dispersed in the volatile aqueous liquid medium, the binder comprising: (1) water-soluble film-forming organic polymer which is substantially free of ammonium groups, (2) water-soluble first cationic addition polymer consisting essentially of quaternary ammonium-containing mer units and ammonium-free mer units, and (3) water-soluble second cationic addition polymer consisting essentially of secondary, tertiary, or both secondary and tertiary ammonium-containing mer units and ammonium-free mer units, wherein the binder constitutes from 20 to 90 percent by weight of the solids of the coating composition; and (c) finely divided substantially water-insoluble filler particles which have a maximum dimension of less than 500 nanometers and constitute from 10 to 80 percent by weight of the solids of the coating composition.
Another embodiment of the invention is a printing medium comprising a substrate having at least one surface and a coating on the surface wherein the coating comprises: (a) binder comprising: (1) organic polymer which is substantially free of ammonium groups, (2) first cationic addition polymer consisting essentially of quaternary ammonium-containing mer units and ammonium-free mer units, and (3) second cationic addition polymer consisting essentially of secondary, tertiary, or both secondary and tertiary ammonium-containing mer units and ammonium-free mer units, wherein the binder constitutes from 20 to 90 percent by weight of the solids of the coating; and (b) finely divided substantially water-insoluble filler particles which have a maximum dimension of less than 500 nanometers, are distributed throughout the binder, and constitute from 10 to 80 percent by weight of the solids of the coating.
Yet another embodiment of the invention is a printing process which comprises applying liquid ink droplets to the printing medium of the second embodiment.
The printing media of the invention may be made by coating a surface of a substrate with the coating composition of the invention and thereafter substantially removing the aqueous liquid medium.
The coating composition can be in the form of an aqueous solution in which case the volatile aqueous liquid medium is a volatile aqueous solvent for the polymer of the binder, or the coating composition can be in the form of an aqueous dispersion in which instance the volatile aqueous liquid medium is a volatile aqueous dispersion liquid for at least some of the polymer of the binder.
The volatile aqueous liquid medium 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.
It is preferred that substantially no low boiling volatile water-miscible organic liquids be intentionally added to the system in order to minimize organic emissions upon drying the coating.
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 is by no means exhaustive.
It is preferred that substantially no water-miscible organic liquids which are of low, moderate, or negligible volatility be intentionally added to the system.
Notwithstanding the above, those materials which, although not intentionally added for any particular purpose, are normally present as impurities in one or more of the components of the coating compositions of the invention and which become components of the volatile aqueous liquid medium, may be present at low concentrations.
In most instances water constitutes at least 80 percent by weight of the volatile aqueous liquid medium. Often water constitutes at least 95 percent by weight of the volatile aqueous liquid medium. Preferably water constitutes substantially all of the volatile aqueous liquid medium.
The amount of volatile aqueous liquid medium present in the coating composition may vary widely. The minimum amount is that which will produce a coating composition having a viscosity low enough to apply as a coating. The maximum amount is not governed by any theory, but by practical considerations such as the cost of the liquid medium, the minimum desired thickness of the coating to be deposited, and the cost and time required to remove the volatile aqueous liquid medium from the applied wet coating. Usually, however, the volatile aqueous liquid medium constitutes from 75 to 98 percent by weight of the coating composition. In many cases the volatile aqueous liquid medium constitutes from 85 to 98 percent by weight of the coating composition. Often the volatile aqueous liquid medium constitutes from 86 to 96 percent by weight of the coating composition. Preferably the volatile aqueous liquid medium constitutes from 88 to 95 percent by weight of the composition.
The water-soluble film-forming organic polymer which is substantially free of ammonium groups and which may be used in the present invention are numerous and widely varied.
Examples include poly(ethylene oxide), poly(vinyl alcohol), poly(vinyl pyrrolidone), water-soluble cellulosic organic polymer, or a mixture of two or more thereof.
Water-soluble poly(ethylene oxide) is known. Such materials are ordinarily formed by polymerizing ethylene oxide [CAS 75-21-8], usually in the presence of a small amount of an initiator such as low molecular weight glycol or triol. Examples of such initiators include ethylene glycol [CAS 107-21-1], diethylene glycol [CAS 111-46-6], triethylene glycol [CAS 112-27-6], tetraethylene glycol [CAS 112-60-7], propylene glycol [CAS 57-55-6], trimethylene glycol [CAS 504-63-2], dipropylene glycol [CAS 110-98-5], glycerol [CAS 56-81-5], trimethylolpropane [CAS 77-99-6], and &agr;,&ohgr;-diaminopoly(propylene glycol) [CAS 9046-10-0]. One or more other lower alkylene oxides such as propylene oxide [CAS 75-56-9] and trimethylene oxide [CAS 503-30-0] may also be employed as comonomer with the ethylene oxide, whether to form random polymers or block polymers, but they should be used only in those small amounts as will not render the resulting polymer both water-insoluble and nondispersible in water. As used herein and in the claims, the term “poly(ethylene oxide)” is intended to include the foregoing copolymers of ethylene oxide with small amounts of lower alkylene oxide, as well as homopolymers of ethylene oxide. The configuration of the poly(ethylene o
Allison William C.
Cho Suk H.
Nehmsmann Louis J.
Tang Robert H.
Wang Alan E.
Hewlett--Packard Company
Jagannathan Vasu
Shosho Callie E
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