Waterfast inks via cyclodextrin inclusion complex

DETAILED DESCRIPTION What is claimed is: 1.
A liquid ink suitable for ink-jet printing, comprising, by weight: (a) a vehicle comprising about 90 to 98 wt.
% water and the balance at least one member selected from the group consisting of glycols and lactams; (b) about 0.
5 to 9 wt.
% of a water-insoluble dye; and (c) a cyclodextrin, present in an amount of at least about twice the concentration of said dye.
2.
The ink of claim 1 wherein said cyclodextrin is selected from the group consisting of .
alpha.
-cyclodextrin, .
beta.
-cyclodextrin, and .
gamma.
-cyclodextrin.
3.
The ink of claim 1 wherein said dye is selected from the group consisting of solvent dyes, vat dyes, and insoluble mordant dyes.
4.
The ink of claim 1 wherein said at least one glycol is present in a range from about 2 to 10 wt.
%.
5.
The ink of claim 1 wherein said lactam consists essentially of at least one pyrrolidone present in a range from about 7 to 10 wt.
%.
6.
The ink of claim 1 wherein said dye is present in an amount ranging from 4 to 5 wt.
%.
7.
The ink of claim 1 consisting essentially of 4% Neazopon Black X52, 10%, .
alpha.
-cyclodextrin, 5.
5% diethylene glycol, and the balance water.
8.
A method for providing a liquid ink having improved waterfastness, comprising (a) preparing a vehicle comprising, by weight, about 90 to 98 wt.
% water and the balance at least one member selected from the group consisting of glycols and lactams; (b) adding thereto a first amount of a cyclodextrin; (c) adding thereto a second amount of a water-insoluble dye, said amount of said dye ranging from about 0.
5 to 9 wt.
% of said ink and wherein said first amount of said cyclodextrin is approximately at least twice the concentration of said dye; and (d) heating said ink at an elevated temperature ranging from about 40.
degree.
to 60.
degree.
C.
to form a complex between said cyclodextrin and said dye.
9.
The method of claim 8 wherein said second amount of said dye ranges from about 4 to 5 wt.
% of said ink.
10.
The method of claim 8 wherein said cyclodextrin is selected from the group consisting of