Aqueous ink composition and ink-jet printing method using the same

DETAILED DESCRIPTION Accordingly, a first object of the present invention is to provide an aqueous ink composition suitable for the ink-jet printing, with excellent drying characteristics, penetrating property and preservation stability, capable of producing high quality images not deteriorating over a long period of time on an image-receiving medium.
A second object of the present invention is to provide an ink-jet printing method of recording high quality color images on a sheet of plain paper using the above-mentioned aqueous ink composition.
The above-mentioned first object of the present invention can be achieved by, an aqueous ink composition comprising water, a lubricant, a coloring agent dispersed or dissolved in water, and a compound represented by formula (I): R--O(CH.
sub.
2 CH.
sub.
2 O).
sub.
m CH.
sub.
2 COOM (I) wherein R is an alkyl group having 6 to 14 carbon atoms; M is a cation selected from the group consisting of alkali metal ion, quaternary ammonium cation, quaternary phosphonium cation, alkanol amine cation; and m is an integer of 3 to 12.
The second object of the present invention can be achieved by a method of recording color images on an image-receiving medium, comprising the step of ejecting an aqueous ink composition in the form of droplets from nozzles onto an image-receiving medium with a Stockigt sizing degree of 3 seconds or more as defined in the Japanese Industrial Standards P-8122 (hereinafter referred to as JIS-P-8122), the aqueous ink composition comprising water, a lubricant, a coloring agent dispersed or dissolved in water, and a compound represented by formula (I): R--O(CH.
sub.
2 CH.
sub.
2 O).
sub.
m CH.
sub.
2 COOM (I) wherein R is an alkyl group having 6 to 14 carbon atoms; M is a cation selected from the group consisting of alkali metal ion, quaternary ammonium cation, quaternary phosphonium cation, and alkanol amine cation; and m is an integer of 3 to 12.