Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2001-01-26
2003-04-15
Hess, Bruce H. (Department: 1774)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C428S195100
Reexamination Certificate
active
06547386
ABSTRACT:
FIELD OF THE INVENTION
Ser. No. 09/770,431 by Lawrence et al., filed Jan. 26, 2001 entitled “Ink Jet Printing Method”.
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. A crack-free surface appearance 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 surface yet is fast-drying.
U.S. Pat. No. 6,037,050 and EP 888,904 relate to an ink jet recording element wherein an ink absorption layer comprises inorganic particles such as silica and a poly(vinyl alcohol) binder that is crosslinked with a hardener. However, there is no disclosure in these references that the poly(vinyl alcohol) binder should have a certain viscosity or that the inorganic particles comprise a fumed metallic oxide.
It is an object of this invention to provide a method for using a porous ink jet recording element that exhibits good overall appearance without cracking and has an excellent dry time.
SUMMARY OF THE INVENTION
These and other objects are achieved in accordance with the invention which comprises an ink jet printing method, comprising the steps of:
A) providing an ink jet printer that is responsive to digital data signals;
B) loading the printer with an ink jet recording element comprising a support having thereon a porous image-receiving layer comprising particles and a poly(vinyl alcohol) binder, the particles comprising a fumed metallic oxide, and the binder having an average viscosity greater than about 25 cp at 4% solids in an aqueous solution at 20° C.;
C) loading the printer with an ink jet ink composition; and
D) printing on the image-receiving layer using the ink jet ink composition in response to the digital data signals.
By use of the process of the invention, a porous ink jet recording element is obtained that exhibits good overall appearance without cracking and has an excellent dry time.
DETAILED DESCRIPTION OF THE INVENTION
Any fumed metallic oxide particles may be used in the invention. Examples of such particles include fumed alumina, silica, titania, cationic silica, antimony(III) oxide, chromium(III) oxide, iron(III) oxide, germanium(IV) oxide, vanadium(V) oxide, or tungsten(VI) oxide. In a preferred embodiment, fumed alumina, fumed silica or cationic fumed silica is employed. Fumed oxides are available in dry form or as dispersions. The fumed metallic oxide particles may be porous or nonporous.
The fumed metallic oxide particles used in the invention may be in the form of primary particles or in the form of secondary aggregated particles. Preferred aggregates are comprised of smaller primary particles about 7 to about 40 nm in diameter and are 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.
The process for fuming metallic oxides is well known in the art. For example, reference may be made to Technical Bulletin Pigments, no. 56, Highly Dispersed Metallic Oxides Produced by the AEROSIL® Process, by Degussa AG., 1995.
Porosity of an image-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.
As noted above, the poly(vinyl alcohols) useful in the invention have an average viscosity greater than about 25 cp when employed in a 4% aqueous solids solution at 20° C. Specific examples of such poly(vinyl alcohols) which may be used in the invention include the following:
TABLE 1
Poly (vinyl alcohol)
Average Viscosity @ 4% (cp)*
PVA-A
Gohsenol ® GH-17
30
PVA-B
Gohsenol ® GH-23
52
PVA-C
Gohsenol ® N300
27.5
*Trade publication, Nippon Gohsei Co., Ltd.
The amount of poly(vinyl alcohol) binder used should be sufficient to impart cohesive strength to the image-receiving layer, but as small as possible so that the interconnected pore structure formed by the aggregates is not filled in by the binder. In a preferred embodiment of the invention, the weight ratio of the binder to the particles is from about 1:20 to about 1:5.
The image-receiving layer may also contain a mordant and/or a crosslinker for crosslinking the poly(vinyl alcohol). Examples of mordants which may be used include water-soluble cationic polymers, metal salts, water-insoluble cationic polymeric particles 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. 09/770,128 of Lawrence et al., Ink Jet Printing Method, filed Jan. 26, 2001; and U.S. patent application Ser. No. 09/770,127 of Lawrence et al., Ink Jet Printing Method, filed Jan. 26, 2001, the disclosures of which are hereby incorporated by reference.
Examples of crosslinkers which may be used include carbodiimides, polyfunctional aziridines, aldehydes, isocyanates, epoxides, polyvalent metal cations, acetals, ketals, etc. In a preferred embodiment of the invention, the crosslinker is an aldehyde, an acetal or a ketal. In a more preferred embodiment, the crosslinker is 2,3-dihydroxy-1,4-dioxane.
Since the image-receiving layer is a porous layer comprising particles, the void volume must be sufficient to absorb all of the printing ink. For example, if a porous layer has 60 volume % open pores, in order to instantly absorb 32 cc/m
2
of ink, it must have a physical thickness of at least about 54 &mgr;m.
The support for the ink jet recording element used in the in
Bermel Alexandra D.
Shaw-Klein Lori J.
Cole Harold E.
Eastman Kodak Company
Grendzynski Michael E.
Hess Bruce H.
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