Pigmented magenta inks and their use in ink jet printing
Publication Date: 2004-May-19
The IP.com Prior Art Database
The present disclosure relates to pigmented magenta inks that are especially suitable for the printing of various recording materials (such as paper, film, cloth) with the ink jet printing method.
The present disclosure relates to pigmented magenta inks that are especially suitable for the printing of various recording materials (such as paper, film, cloth) with the ink jet printing method. By the ink jet printing method, images and characters are usually printed by subtractive color mixing of inks of four colors, namely Yellow (Y), Magenta (M), Cyan (C) and Black (K). Ink jet printers, particularly those for use in the home or office, generally use aqueous inks, and such inks commonly employ dyes as colorants. In many applications, inks are subject to high demands in terms of their optical density, color brilliance and fastness to humidity, light and atmospheric pollutants. Because of image fastness requirements, there is considerable interest in the use of pigmented inks for ink jet printing applications. Indeed, it is well-known that pigmented inks offer improved fastness to washing and weathering of the prints produced and better light stability on outdoor exposure than those based on colorants. For instance, most pigmented magenta ink jet inks are based on C.I. Pigment Red 122 (2,9-dimethylquinacridone), C.I. Pigment Red 202 (2,9-dichloroquinacridone) or C.I. Pigment Violet 19 (quinacridone), which are all offering outstanding light fastness. However, it is also well known that it is difficult to match the brilliance of dye-based inks with pigmented inks in general, and the brilliance of dye-based magenta inks with pigmented magenta inks in particular. 2,9-dimethylquinacridone pigments having a very small particle size (less than 100 nm) are increasingly used because of their improved coloristic properties. However, a need still exists for magenta pigmented inks with higher chromaticity for multicolor ink jet printing.
It has now been found that certain quinacridone magenta pigments enable to formulate magenta pigmented ink jet inks with outstanding color brilliance. The obtained inks are expected to improve color reproduction when used in combination with a CMYK ink set or with a CMYK ink set already complemented with additional color inks, such as Light Cyan, Light Magenta, Orange, Green or Red inks. Quinacridone pigments according to the present disclosure are solid solutions of quinacridone (C.I. Pigment Violet 19) and 2,9-dichloro-quinacridone (C.I. Pigment Red 202) as described in e.g. U.S. Pat. 3,607,336 and U.S. Pat. 4,015,998. The quinacridone mixture is optionally surface treated with a pyrazole derivative of quinacridone and / or a sulfonated derivative of quinacridone, as described in e.g. U.S. Pat. 5,334,727, examples 11 to 13.
Ink jet inks according to this disclosure typically comprise:
(i) from 1 to 10 parts of an aqueous dispersion of a quinacridone pigment mixture according to the disclosure
(ii) from 0.01 to 10 parts of a pigment dispersant and / or a surfactant or a mixture of such compounds
(iii) from 1 to 60 parts of water-soluble organic solvent or a m...