Stock material or miscellaneous articles – Ink jet stock for printing – Particles present in ink receptive layer
Reexamination Certificate
2001-08-31
2003-11-04
Hess, B. Hamilton (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Particles present in ink receptive layer
C428S032340
Reexamination Certificate
active
06641875
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink jet recording element, more particularly 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.
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 that occurs when the dye molecules penetrate too far into the porous layer.
World Publication 00/01539 discloses a porous ink jet recording element containing first and second group particles, the first group comprising metal oxide particles which are aggregates of smaller, primary particles with a mean diameter of the aggregates from about 100 nm to about 500 nm and the second group comprising of particles with a mean diameter less than 50% of the mean diameter of the aggregates in the first group. However, there is a problem with this recording element in that it has a poor dry time as will be shown hereinafter.
It is an object of this invention to provide a porous ink jet recording element that has a good image quality with good gloss and has an excellent dry time.
SUMMARY OF THE INVENTION
These and other objects are achieved in accordance with the invention which comprise an ink jet recording element comprising a support having thereon a porous image-receiving layer comprising at least about 50% by weight of particles and less than about 20% by weight of a binder, the particles comprising a mixture of
(a) inorganic particles having a primary particle size of from about 7 to about 40 nm in diameter which may be aggregated to provide a mean aggregate particle size of up to about 500 nm; and
(b) colloidal particles having a mean particle size of from about 20 to about 500 nm;
and wherein the difference between the mean aggregate particle size of the inorganic particles and the mean particle size of the colloidal particles is within about 10%.
By use of the invention, a porous ink jet recording element is obtained that has a good image quality with good gloss and has an excellent dry time.
DETAILED DESCRIPTION OF THE INVENTION
The porous image-receiving layer useful in the invention comprises at least about 50% by weight of particles, preferably from about 80-90% by weight, and less than about 20% by weight of binder. This amount of binder will insure that the layer is porous, i.e., have interconnecting voids so that a solvent in the ink jet ink used in printing on the recording element can travel through the image-receiving layer to a support or base layer if one is present.
Examples of (a) inorganic particles useful in the invention include alumina, boehmite, hydrated alumina, silica, titanium dioxide, zirconium dioxide, clay, calcium carbonate, inorganic silicates or barium sulfate. The particles may be porous or nonporous. In a preferred embodiment of the invention, the (a) inorganic particles are metallic oxides, preferably fumed. Preferred examples of fumed metallic oxides which may be used include silica and alumina fumed oxides. Fumed oxides are available in dry form or as dispersions of the aggregates.
In another preferred embodiment of the invention, the (a) inorganic particles may be in the form aggregated particles. The aggregates are comprised of smaller primary particles about 7 to about 40 nm in diameter, and are aggregated up to about 500 nm in diameter. In still another preferred embodiment, the (a) inorganic particles have a mean aggregate particle size of from about 50 nm to about 200 nm.
Examples of (b) colloidal particles useful in the invention include alumina, boehmite, hydrated alumina, silica, titanium dioxide, zirconium dioxide, clay, calcium carbonate, inorganic silicates, barium sulfate or organic particles such as polymeric beads. Examples of organic particles useful in the invention are disclosed and claimed in U.S. patent application Ser. No. 09/458,401, filed Dec. 10, 1999; Ser. No. 09/608,969, filed Jun. 30, 2000; Ser. No. 09/607,417, filed Jun. 30, 2000; Ser. No. 09/608,466 filed Jun. 30, 2000; Ser. No. 09/607,419, filed Jun. 30, 2000; and Ser. No. 09/822,731, filed Mar. 30, 2001; the disclosures of which are hereby incorporated by reference. In a preferred embodiment of the invention, the (b) colloidal particles are silica, alumina, boehmite or hydrated alumina. The particles may be porous or nonporous. In another preferred embodiment of the invention, the (b) colloidal particles may be in the form of primary particles. In yet another preferred embodiment of the invention, the mean particle size of the primary particles may range from about 20 nm to about 500 nm.
In a preferred embodiment of the invention, the first (a) inorganic particles comprise from about 5 to about 25% by weight of the particle mixture. In another preferred embodiment, the first (a) inorganic particles have a mean aggregate particle size of from about 50 nm to about 200 nm. In yet another preferred embodiment, the (b) colloidal particles have a mean particle size of from about 50 nm to about 200 nm.
The above particles are preferred for ink jet recording elements because they possess positively charged surfaces, which are capable of binding anionic inkjet printing dyes, rendering printed images resistant to dye migration due to water and high humidity conditions.
It has been found that the size difference between the (a) first inorganic particles and the (b) colloidal particles determines the dry time of the ink jet recording element. If the mean particle size of the (b) particles is much smaller than the mean aggregate particle size of the (a) first inorganic particles, then the (b) colloidal particles may fill in the void space between the (a) first inorganic particles in the dry coating, which would reduce the porosity of the image-receiving layer. A reduction in porosity of the image-receiving layer would reduce the dry time of the image-recording element.
In general, any binder may be used in the image-receiving layer of the invention. In a preferred embodiment, the binder is a hydrophilic polymer such as poly(vinyl alcohol), poly(vinyl pyrrolidone), gelatin, cellulose ethers, poly(oxazolines), poly(vinylacetarnides), partially hydrolyzed poly(vinyl acetate/vinyl alcohol), poly(acrylic acid), poly(acrylamide), poly(alkylene oxide), sulfonated or phosphated polyesters and polystyrenes, casein, zein, albumin, chitin, chitosan, dextran, pectin, collagen derivatives, collodian, agar—agar, arrowroot, guar, carrageenan, tragacanth, xanthan, rhamsan and the like. In another preferred embodiment, the hydrophilic binder is poly(vinyl alcohol). The polymeric binder should be chosen so that it is compatible with the afore
Baier John M.
Chu Lixin
Gallo Elizabeth A.
Sadasivan Sridhar
Cole Harold E.
Eastman Kodak Company
Hess B. Hamilton
Leipold Paul A.
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