Patent ID: 6715869
Filing Date: 2004-04-06
Classification: C09D

Abstract:
A pigment-based ink set for ink jet printing, the ink set comprising at least one pigment-based ink; wherein the normalized differential specular reflectance for each ink in the set, N&Dgr;RS(X), is less than 1.25 when calculated according to Equation 1:N&Dgr;RS(X)=[N&Dgr;RS(Xn)]maxâ€ƒâ€ƒEquation 1 where X represents the ink, n is an integer associated with each density patch printed on an image-recording element as part of a test image, and [N&Dgr;RS(Xn)]max is the maximum value of the [N&Dgr;RS(Xn)] values that are calculated for the density patches printed using ink X; wherein the image-recording element has a gloss value of at least about 5 when measured at 60Â°; wherein the test image for ink X consists of a series of at least ten density patches printed such that the ink laydown of the patches increases incrementally, from no ink laydown to a maximum level generating a density of at least about 1.5; and wherein the normalized differential specular reflectance value for each patch, N&Dgr;RS(Xn), is determined according to Equation 2: N&it;â€ƒ&it;Î”&it;â€ƒ&it;RS&af;(Xn)=[RSmax&af;(Xn)-RSmin&af;(Xn)]RSmean&af;(Xn)Equation&it;â€ƒ&it;2where RSmax(Xn) is the maximum specular reflectance over the visible spectral region between 390 nm and 720 nm for patch Xn, RSmin(Xn) is the minimum specular reflectance over the visible spectral region between 390 nm and 720 nm for patch Xn, and RSmean(Xn) is the average specular reflectance over the visible spectral region between 390 nm and 720 nm for patch Xn.