Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2001-01-26
2002-10-01
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C342S100000, C428S195100
Reexamination Certificate
active
06457825
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for using 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. 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.
Another problem encountered with a recording element is ink coalescence which occurs when adjacent ink dots coalesce which leads to nonuniform density.
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 crosslinker should be present in an amount greater than 10%, based on the binder.
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 and reduced ink coalescence.
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, a poly(vinyl alcohol) binder and a crosslinking agent, the 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 the crosslinking agent being present in an amount of at least about 20 weight % of the poly(vinyl alcohol) binder;
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 and reduced ink coalescence.
DETAILED DESCRIPTION OF THE INVENTION
Examples of 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 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.
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. Preferred examples of fumed metallic oxides which may be used in the invention include silica and alumina fumed oxides. Fumed oxides are available in dry form or as dispersions of the aggregates mentioned above.
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.
Any poly(vinyl alcohol) may be used in the invention. In a preferred embodiment, the poly(vinyl alcohol) has an average viscosity greater than about 20 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
1
PVA-B
Gohsenol ® GH-23
52
1
PVA-C
Gohsenol ® N300
27.5
1
PVA-D
Elvanol ® 52-22
23.5
2
1
Trade publication, Nippon Gohsei Co., Ltd.
2
Trade publication, DuPont Corp.
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. 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 Jan. 26, 2001, 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 disclosure
Bermel Alexandra D.
Shaw-Klein Lori J.
Barlow John
Cole Harold E.
Eastman Kodak Company
Shah Manish S.
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