Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2001-01-26
2003-04-15
Schwartz, Pamela R. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
Reexamination Certificate
active
06548151
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a porous ink jet recording element.
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 ink jet 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 a porous recording element is manufactured, it is difficult to co-optimize the image receiving layer surface appearance and ink drying times. Good image-receiving layer surface appearance is obtained when it is virtually crack-free and has high gloss. A crack-free surface appearance and high gloss can
When a porous recording element is manufactured, it is difficult to co-optimize the image-receiving layer surface appearance and ink drying times. Good image-receiving layer surface appearance is obtained when it is virtually crack-free and has high gloss. A crack-free surface appearance and high gloss can be obtained merely by adding more binder to the image-receiving layer. However, adding more binder increases dry time since the binder fills the pores in the image-receiving layer. Therefore, it is difficult to obtain an image-receiving layer which has a crack-free, glossy surface yet is fast-drying.
In addition, when a porous recording element is printed with dye-based inks, the dye molecules penetrate the coating layers. However, there is a problem with such porous recording elements in that the optical densities of images printed thereon are lower than one would like. The lower optical densities are believed to be due to optical scatter which occurs when the dye molecules penetrate too far into the porous layer. Thus, it is very difficult to obtain an image-receiving layer which has a crack-free, glossy surface yet is fast-drying, and in addition has high image density when printed.
EP 1,002,660 relates to a porous ink jet recording element comprising fine particles, hydrophilic binder and a water-soluble, cationic polymer. However, there is a problem with this element in that the density of an image printed on such an element using a water-soluble cationic polymer is lower than one would like.
It is an object of this invention to provide a porous ink jet recording element that has a good overall appearance with high gloss without cracking, has an excellent dry time and has high image densities when printed.
SUMMARY OF THE INVENTION
These and other objects are achieved in accordance with the invention which comprises an ink jet recording element comprising a support having thereon in order:
I) a porous base layer comprising particles having a primary particle size of from about 7 to about 40 nm in diameter which may be aggregated up to about 300 nm and which are dispersed in a binder; and
II) a porous image-receiving layer comprising:
(a) particles having a primary particle size of from about 7 to about 40 nm in diameter which may be aggregated up to about 300 nm; and
(b) water insoluble, cationic, polymeric particles comprising at least about 20 mole percent of a cationic mordant moiety;
the thickness of layer I) being between about 35 and about 50 &mgr;m and the thickness of layer II) being between about 2 and about 6 &mgr;m.
By use of the invention, a porous ink jet recording element is obtained that has a good overall appearance with high gloss without cracking, has an excellent dry time and has high image densities when printed.
DETAILED DESCRIPTION OF THE INVENTION
As noted above, the recording element of the invention contains a base layer containing certain particles, next to the support, the function of which is to absorb the solvent from the ink. These particles may be the same or different from the (a) particles in the image-receiving layer, described hereinafter. This base layer may also contain a binder, such as those binders described hereinafter for the image-receiving layer.
Examples of (a) particles useful in the invention include alumina, boehmite, clay, calcium carbonate, titanium dioxide, calcined clay, aluminosilicates, silica, barium sulfate, or polymeric beads. The particles may be porous or nonporous. In a preferred embodiment of the invention, the particles are metallic oxides, preferably fumed. While many types of inorganic and organic particles are manufactured by various methods and commercially available for an image-receiving layer, porosity of the ink-receiving layer is necessary in order to obtain very fast ink drying. The pores formed between the particles must be sufficiently large and interconnected so that the printing ink passes quickly through the layer and away from the outer surface to give the impression of fast drying. At the same time, the particles must be arranged in such a way so that the pores formed between them are sufficiently small that they do not scatter visible light.
The (a) particles may be in the form of primary particles, or in the form of secondary aggregated particles. The aggregates are comprised of smaller primary particles about 7 to about 40 nm in diameter, and being aggregated up to about 300 nm in diameter. The pores in a dried coating of such aggregates fall within the range necessary to ensure low optical scatter yet sufficient ink solvent uptake.
Preferred examples of fumed metallic oxides which may be used in the invention as the (a) particles include alumina, silica and cationic silica. Fumed metallic oxides are available in dry form or as dispersions of the aggregates mentioned above.
The (b) water insoluble, cationic, polymeric particles comprising at least about 20 mole percent of a cationic mordant moiety useful in the invention can be in the form of a latex, water dispersible polymer, beads, or core/shell particles wherein the core is organic or inorganic and the shell in either case is a cationic polymer. Such particles can be products of addition or condensation polymerization, or a combination of both. They can be linear, branched hyper-branched, grafted, random, blocked, or can have other polymer microstructures well known to those in the art. They also can be partially crosslinked. Examples of core/shell particles useful in the invention are disclosed and claimed in U.S. patent application Ser. No. 09/772,097, of Lawrence et al., Ink Jet Printing Method, filed of even date herewith, the disclosure of which is hereby incorporated by reference. Examples of water dispersible particles useful in the invention are disclosed and claimed in U.S. patent application Ser. No. 09/770,124, of Lawrence et al., Ink Jet Printing Method, filed of even date herewith, U.S. Pat. No. 6,454,404; and U.S. patent application Ser. No. 09/770,127, of Lawrence et al., Ink Jet Printing Method, filed of even date herewith, the disclosures of which are hereby incorporated by reference. Examples of latex particles useful in the invention are disclosed in Ser. No. 09/770,814, by Bermel et al., filed of even date herewith entitled “Ink Jet Recording Element”, the disclosure of which is hereby incorporated by reference. In a preferred embodiment, the
Bermel Alexandra D.
Shaw-Klein Lori J.
Cole Harold E.
Schwartz Pamela R.
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