Use of monomeric and oligomeric additives to stabilize dyes on porous ink jet medias

#The present invention relates to a print medium for use in ink-jet printing and, more specifically, to incorporating an additive into the print medium to produce a print medium with improved permanence.

#The use of inkjet printing systems in offices and homes has grown dramatically in recent years. The growth can be attributed to drastic reductions in cost of inkjet printers and substantial improvements in print resolution and overall print quality. While the print quality has drastically improved, research and development efforts continue toward improving the permanence of inkjet images because this property still falls short of the permanence produced by other printing and photographic techniques. A continued demand in inkjet printing has resulted in the need to produce images of high quality, high permanence, and high durability, while maintaining a reasonable cost.

#In inkjet printing, the inkjet image is formed on a print medium when a precise pattern of dots is ejected from a drop-generating device known as a print-head. The typical inkjet printhead has an array of precisely formed nozzles located on a nozzle plate and attached to an inkjet printhead array. The nozzles are typically 30 to 40 μm in diameter. The inkjet printhead array incorporates an array of firing chambers that receive liquid ink, which comprises colorants, pigments, and/or dyes dissolved or dispersed in a liquid vehicle, through fluid communication with one or more ink reservoirs. Each chamber has a thin-film resistor, known as a firing resistor, located opposite the nozzle so ink can collect between the firing resistor and the nozzle. The printhead is held and protected by an outer packaging referred to as a print cartridge or an inkjet pen.

#While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the present invention, the present invention can be more readily ascertained from the following description of the invention when read in conjunction with the accompanying drawings in which:

#FIGS. 1 and 2 show the percentage of cyan dye loss fade for a Cu-phalocyanine based dye blend (Test Ink 1) printed on coated and uncoated nanoporous media; and

#FIGS. 3 and 4 show the percentage of cyan dye loss fade for a Cu-phalocyanine based dye (Test Ink 2) printed on coated and uncoated nanoporous media.

#An additive is used to improve the airfastness of an image printed on print medium coated with the additive of the present invention. The additive may comprise a high molecular weight UV absorber, light stabilizer, free radical scavenger, antioxidant, or fixative. The term “high molecular weight” refers to an additive having a molecular weight of greater than approximately 1000. More preferably, the molecular weight is greater than 1500. This additive may be monomeric or oligomeric. More specifically, the additive may comprise a high molecular weight HALS. In addition, the additive may have low volatility. Preferably, a monomeric or oligomeric HALS having a high molecular weight and low volatility may be used.

#It is also contemplated that more than one additive may be used to obtain the desired airfastness. For example, multiple HALS, antioxidants, or antiozonants may be used or a combination of at least one HALS may be used in combination with at least one antioxidant or at least one antiozonant.

#A monomeric HALS that may be used in the present invention is CHIMASSORB 119, available from Ciba Specialty Chemicals (Vienna, Austria), having the chemical structure R—NH—(CH2)3—NR—(CH2)2—NR—(CH2)3—NH—R, where R is