Stock material or miscellaneous articles – Ink jet stock for printing – Particles present in ink receptive layer
Reexamination Certificate
2002-12-04
2004-07-06
Schwartz, Pamela R. (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Particles present in ink receptive layer
C428S032290, C428S032300, C428S032340, C428S032240, C428S032250
Reexamination Certificate
active
06759106
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.
The inks used in the various ink jet printers can be classified as either dye-based or pigment-based. A dye is a colorant that is dissolved in the carrier medium. A pigment is a colorant that is insoluble in the carrier medium, but is dispersed or suspended in the form of small particles, often stabilized against flocculation and settling by the use of dispersing agents. In either case, the carrier medium can be a liquid or a solid at room temperature. Commonly used carrier media include water, mixtures of water and organic co-solvents and high boiling organic solvents, such as hydrocarbons, esters, ketones, etc.
Dye-based inks and pigment-based inks behave differently when printed on porous recording elements. The dye molecules in dye-based inks are able to penetrate porous layers because they are much smaller than the pores at the surface of the recording element. However, pigment particles are often larger than the pores, and as a result, accumulate at the surface of the recording element even after the printed image is completely dry. The accumulated pigment particles form a layer on the surface that can crack if the surface is not smooth.
EP 0 739 747 A2 and U.S. Pat. Nos. 5,965,244; 6,114,022 and 6,140,406 relate to porous ink jet recording elements containing silica gel which are printed with dye-based inks. However, these recording elements are not suitable for printing with pigment-based inks because the pores at the surfaces are too small relative to pigment particles. In addition, the surfaces are too smooth such that layers formed from accumulated pigment particles crack.
U.S. Pat. No. 5,700,582 relates to the use of nonporous swellable recording elements for printing with pigment-based inks. However, these recording elements are not suitable for printing with pigment-based inks because it is difficult for pigment particles to diffuse into nonporous ink-receiving layers. Also, nonporous swellable recording elements dry slower than one would like.
It is an object of this invention to provide a porous ink jet recording element that has good image quality with an excellent dry time. It is another object of the invention to provide a porous ink jet recording element having a smooth surface that, when printed with pigment-based inks, does not cause cracking of layers formed by accumulated pigment particles.
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 a porous image-receiving layer comprising at least 30% by weight of particles and at least 30% by weight of a binder, the particles comprising a mixture of
a) silica gel particles having an average particle size of greater than about 9 &mgr;m in diameter; and
b) silica gel particles having an average particle size of between about 1 and about 8 &mgr;m in diameter;
wherein the ratio of the a) silica gel particles to the b) silica gel particles is about 0.05 to about 5.
By use of the invention, a porous ink jet recording element is obtained that has a good image quality with an excellent dry time. In addition, the ink jet recording element has a smooth surface that, when printed with pigment based inks, does not cause cracking of films formed by pigment particles that have accumulated at the surface of the recording element.
DETAILED DESCRIPTION OF THE INVENTION
As described above, the image-receiving layer is porous and contains a mixture of particles.
In a preferred embodiment, the a) silica gel particles have an average particle size of greater than about 10 &mgr;m in diameter. In another preferred embodiment, the b) silica gel particles have an average particle size of between about 2 and about 6 &mgr;m in diameter. The a) and b) silica gel particles are used in an amount of at least about 30 wt. %, preferably from about 40-60 wt. %.
Examples of a) silica gel particles which may be used in the invention include the following: Gasil® IJ45 (Ineos Co.), avg. particle size of 10.1 &mgr;m; Gasil® HP 39 (Ineos Co.), avg. particle size of 10.3 &mgr;m; Gasil® HP395 (Ineos Co.), avg. particle size of 14.5 &mgr;m; Syloid® C812 (Grace-Davison Co.), avg. particle size of 12 &mgr;m; Syloid® 620(Grace-Davison Co.), avg. particle size of 12 &mgr;m; Sylojet® P409(Grace-Davison Co.), avg. particle size of 9 &mgr;m; Sylojet® P412 (Grace-Davison Co.), avg. particle size of 12 &mgr;m; Sylojet® P416 (Grace-Davison Co.), avg. particle size of 16 &mgr;m; and Mizukasil® P-78F (Mizusawa Industrial Chemicals, LTD. Co.), avg. particle size of 12.5 &mgr;m.
Examples of b) silica gel particles which may be used in the invention include the following: Gasil® IJ35 (Ineos Co.), avg. particle size of 4.5 &mgr;m; Gasil® IJ37 (Ineos Co.), avg. particle size of 5.8 &mgr;m; Gasil® HP210 (Ineos Co.), avg. particle size of 6.4 &mgr;m; Gasil® HP260 (Ineos Co.), avg. particle size of 6.6 &mgr;m; Sylojet® P403 (Grace-Davison Co.), avg. particle size of 3 &mgr;m; Sylojet® P405(Grace-Davison Co.), avg. particle size of 5 &mgr;m; Sylojet® P407 (Grace-Davison Co.), avg. particle size of 7 &mgr;m; Mizukasil® P-78A (Mizusawa Industrial Chemicals, LTD. Co.), avg. particle size of 3.3 &mgr;m; and Mizukasil® P-78D (Mizusawa Industrial Chemicals, LTD. Co.), avg. particle size of 7.0 &mgr;m.
The image-receiving layer also comprises a hydrophilic polymer that functions as a binder for the silica gel particles. The binder is used in an amount that imparts cohesive strength to the layer, but should also be minimized so that the layer is porous, i.e., has interconnecting voids so that the carrier medium of an 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. The amount of hydrophilic binder is at least about 30 wt. %, preferably from about 40-60 wt. %.
In a preferred embodiment of the invention, the binder is poly(vinyl alcohol), poly(vinyl pyrrolidone), gelatin, a cellulose ether, a poly(oxazoline), a poly(vinylacetamide), a partially hydrolyzed poly(vinyl acetate/vinyl alcohol), a poly(acrylic acid), a poly(acrylamide), a poly(alkylene oxide), a sulfonated or phosphated polyester, polystyrene, 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 polymer is poly(vinyl alcohol). The hydrophilic polymer should be chosen so that it is compatible with the aforementioned a) and b) silica gel particles.
The image-receiving layer of the invention may optionally comprise one or more mordants in order to improve water and humidity resistance. Such mordants are well known in the art of ink jet printing and typically comprise a water soluble or water dispersible cationic polyme
Chu Lixin
Gallo Elizabeth A.
Ruschak Kenneth J.
Salerno Charles R.
Shaw-Klein Lori J.
Cole Harold E.
Eastman Kodak Company
Schwartz Pamela R.
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