Inkjet print and a method of printing

#The present invention relates to an image recording element and a printing method using the element. More specifically, the invention relates to a recording medium in which the top layer comprises fusible particles.

#In a typical inkjet 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 inkjet 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. Transparent swellable hydrophilic polymer layers do not scatter light and therefore afford high image density and gamut, but tend to take longer time to dry. On the other hand, porous ink-receiving layers, which usually comprise inorganic or organic particles and a binder, can rapidly absorb ink droplets into the coating through capillary action, during the inkjet printing process, so that the image is dry-to-touch right after it comes out of the printer. Therefore, porous layers allow a fast “drying” of the ink and produce a smear-resistant image. However, such porous layers, by virtue of the large number of air-particle interfaces, tend to scatter light, which can result in lower densities of printed images.

#FIG. 1 is a photomicrograph of a cross-section of a printed fused inkjet recording medium prepared in accordance with the method of the present invention.

#The porous layers of the element used in the method have relevant functionality with regard to both ink-fluid-transport and ink-pigment filtration. With regard to the former, the porous upper fusible, preferably the uppermost or top layer, has a median pore size larger than the ink-fluid-receiving layer, i.e., the adjacent underlying or lower layer. This pore-size hierarchy establishes a capillary pressure in the printed areas that drives the ink fluid from the upper into the underlying layer. With regard to ink pigment filtration, the median pore size of the upper layer must be larger than the mean particle size of the ink pigment, which allows the ink-pigment particles to move with the ink fluid within the pore structure of the upper fusible layer. Concomitantly, the median pore size of the lower layer must be smaller than the ink pigment mean particle size, so that pigment particles cannot not substantially enter the pore structure of the lower layer. As capillary pressure drives the ink fluid into the lower layer, the ink-pigment particles are, in effect, filtered at or near the interface between the upper and lower layers.

#A preferred embodiment of the present method is directed to inkjet printing a color image on an inkjet recording element, which method comprises: a) providing an inkjet printer that is responsive to digital data signals; b) loading the printer with a fusible inkjet recording element having a support and thereon, in order from the support, a porous ink-fluid-receiving layer and a porous upper fusible layer adjacent and overlying the ink-fluid-receiving layer, and c) loading the printer with a plurality of inkjet ink compositions including at least a cyan, yellow, and magenta ink composition, wherein at least one, preferably all three of the ink compositions comprise pigment colorant particles pigment whose mean pigment particle size is smaller than about 80 percent, preferably smaller than 70 percent, of the median pore size of the upper fusible layer, but larger than 80 percent of the median pore size of the adjacent underlying ink-fluid-receiving layer, wherein the thickness of the porous fusible layer is from 1 to 50 micrometers, preferably 10 to 30 micrometers, d) printing on the fusible inkjet recording element using the inkjet ink composition in response to the digital data signals; and e) fusing the printed element to obtain a fused upper layer; as determinable by printing a uniform test area with at least one, preferably all three, of said pigment-based ink compositions to an optical density of between 1.0 and 2.5 and then fusing the printed element, resulting in greater than 50%, preferably greater than 60 percent, of the pigment colorant in the pigment-based ink is retained in the bottom half of the fused upper layer, as determined by optical micro-densitometry on a cross-section of the test area of the fused printed element, in accordance with the measurement described in the examples below.

#The ink compositions mentioned above are for use in a colored printer and comprise at least cyan, yellow, and magenta-colored ink compositions. Other ink compositions can optionally achieve the ink-pigment stratification of the present invention, including black ink compositions and other colored ink compositions. Conventional inkjet printers now commonly have 4 to 8 different colored inks in addition to black, especially for photographic quality inkjet printers.