Ink jet printing with uniform gloss

#This invention pertains to a method of ink jet printing, in particular to a method of ink jet printing with an ink set comprising a gloss equalizing colorless ink.

#For photographic and other high definition imaging, uniform, high gloss is desirable to enhance the perception of clarity and sharpness of image. Ink jet printers can be used to print digital images with photographic quality if a suitable recording medium, such as glossy ink jet paper, is used. This paper is coated with an ink jet ink receptive layer to carry the image and absorb vehicle (reduce dry time).

#Two types of ink jet receptive coating structures are commonly used for ink jet photo glossy media: swellable-polymer, non-porous media (“polymer” media) and a microporous, porous media (“microporous” media). A third type, often referred to as hybrid ink jet media, makes use of a combination of these coating technologies. The coatings are applied to a substrate such as a cellulose-based sheet or PET film.

#Gloss measurements of various ink/media combinations are provided to demonstrate the lack of uniformity generally present in representative commercial systems. A test pattern of 2.5 cm squares of each ink over a tonal scale of 0% (media) to 100% area fill was printed. The gloss of each area fill was measured with a Byk-Gardner micro-Tri-glossmeter at an angle of 60 degrees, unless otherwise noted, and the values reported in gloss units (GU). In each series of results, the average (avg.) gloss across the range of area fills is provided, along with the standard deviation (std. dev.). The standard deviation is viewed as a measure of gloss uniformity. Within any set of gloss uniformity data, lower standard deviation suggests that the gloss uniformity is better.

#As used herein:

#HP=Hewlett Packard