Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2000-08-31
2002-10-01
Hess, Bruce H. (Department: 1774)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C428S195100
Reexamination Certificate
active
06457824
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
Reference is made to commonly assigned, co-pending U.S. patent application Ser. No. 09/482,659 by Wexler, filed concurrently herewith entitled “Ink Jet Recording Element”; the disclosure of which is hereby incorporated by reference.
FIELD OF THE INVENTION
This invention relates to an ink jet printing method, more particularly to an ink jet printing method using an ink jet recording element which contains thermally compliant composite particles having a core-shell structure.
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, 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 at least one ink-receiving layer. The ink-receiving layer is typically either a porous layer that imbibes the ink via capillary action, or a polymer layer that swells to absorb the ink. Swellable hydrophilic polymer layers take an undesirably long time to dry so that porous layers which dry more rapidly are generally regarded as superior. Ink jet recording elements may contain several layers on the support. Typical two layer constructions have either an uppermost ink transporting layer in combination with a ink retaining underlayer, or an uppermost ink image capture layer in combination with an underlying ink vehicle sump layer.
Porous layers typically contain an easily wettable but water insoluble refractory inorganic pigment as well as a binder. Typically these refractory inorganic pigment particles are comprised of either silica or alumina. The high loading of these easily wettable but refractory particles and the presence of numerous voids, which are essential to the rapid ink absorption of the layer, presents a problem in that the many interfaces presented by such a layer leads to light scattering and results in insufficient gloss. To reduce the scattering of light and thereby improve gloss, porous layers are often comprised principally of colloidal, i.e., less than 0.5&mgr;, particles. However, these particles are difficult to coat without cracking of the coated layer. Thus it is difficult to achieve high gloss with refractory particles larger than about 0.5&mgr;, and conversely it has proven difficult to coat a non-cracking layer with refractory particles smaller than about 0.5&mgr;.
U.S. Pat. No. 5,576,088 relates to an ink jet recording sheet having at least one ink-receiving layer and a gloss-providing layer consisting of a synthetic polymer latex binder and a pigment, at least 70% by weight of which is colloidal particles. The gloss-providing layer may be calendered or pressure contacted to a heated specular roll immediately after coating to further enhance the gloss. However, there are problems with this recording sheet in that the use of organic particles decreases the releasability of the gloss-providing layer from the specular roll. Further, calendering the layer prior to imaging decreases ink penetrability. In addition, the above layers have a high loading of colloidal particles so that the layers are prone to cracking due to high drying stresses.
U.S. Pat. No.5,472,773 relates to a coated paper comprising a substrate with a surface layer of colloidal aggregates alumina crystals (or psuedo-boehmite) and a binder having a specular gloss at 60° of at least 30%. However, there are problems with this coated paper in that this gloss level is less than desirable for high quality imaged substrates and preparing the coated paper requires a costly and complex layer transfer technology.
EP 0 813 978 A1 discloses a porous ink jet recording sheet having solid fine particles in a hydrophilic binder with oil drops to reduce layer brittleness and cracking. However, there is a problem with this element in that oil drops can be exuded from the coating to give an unwanted oily surface feel and diminished gloss.
It is an object of this invention to provide an ink jet printing method using a recording element having a porous top layer that can either transport or retain an ink image, and which can be heat and pressure treated to a high gloss despite the refractory nature of incorporated inorganic pigment particles. Another object of the invention is to provide an ink jet printing method using a glossable ink jet recording element which can be coated and dried without cracking and yet maintain good ink absorptivity.
SUMMARY OF THE INVENTION
These and other objects are provided by the present invention which relates to an ink jet 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 ink jet recording elements comprising a support having thereon, in the order recited, at least one base layer comprising a hydrophilic or porous material and a porous top layer capable of either retaining or transporting an ink image, the porous top layer comprising a polymeric binder and thermally-compliant core-shell particles, the particle-to-binder ratio being between about 95:5 and 50:50, and wherein each the thermally-compliant core-shell particle has:
i) a shell of inorganic colloidal particles, and
ii) a core of a thermoplastic polymer,
the particles having a particle size between about 0.5 &mgr;m and about 10 &mgr;m, the polymeric core having a softening point of greater than about 50° C., and the weight ratio of the shell of the inorganic colloidal particles to the thermoplastic core being from about 1:5 to about 1:99;
C) loading the printer with an ink jet ink composition; and
D) printing on the ink jet recording element using the ink jet ink in response to the digital data signals.
By use of the invention, an ink jet recording element is provided which has a high gloss, does not crack and has good ink absorptivity.
DETAILED DESCRIPTION OF THE INVENTION
The composite thermally-compliant core-shell particles used in the invention may be prepared by several procedures including evaporative limited coalescence, as described in U.S. Pat. No. 4,833,060 and limited coalescence, as described in U.S. Pat. No. 5,354,799, the disclosures of which are hereby incorporated by reference. In both of these preparations, the shell is formed in-situ by a promoter during the preparation of the particle. Alternatively, the shell may be assembled via the layer-by-layer technique on preformed particles as described in “Electrostatic Self-Assembly of Silica Nanoparticle-Polyelectrolyte Multilayers of Polystyrene Latex Particles” in the Journal of the American Chemical Society, vol. 120, p. 8523 (1998).
The thermoplastic core polymer employed in the invention has a softening point greater than about 50° C., and preferably between about 50° C. and about 120° C. A softening point of a polymer can be measured by the Ring and Ball method as described in ASTM E28.
In a preferred embodiment of the invention, the thermoplastic core polymer is a polyester, an acrylic polymer or a styrenic polymer. Examples of these polymers include an amorphous polyester Kao C® (Kao Corp.), an acrylic polymer such as Carboset 526® (BF Goodrich Specialty Chemicals), or a styrene allyl alcohol copolymer such as SAA 100® (Lyondell Chemical Co.).
If the limited coalescence process is used to prepare the composite particles employed in the invention, then monomers and polymerization conditions should be chosen which will polymerize to form a core polymer with a softening point as described above. Suitable monomers include styrenic and vinyl monomers such as styrene, methylmethacrylate or butylacrylate. Mixtures of monomers, such as styrene, butylacrylate and methylmethacrylate may be polymerized to obtain the desired polymer properties.
Suitable colloi
Cole Harold E.
Eastman Kodak Company
Grendzynski Michael
Hess Bruce H.
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