USING POLAR ORGANIC SOLVENT MIXTURES OF DIFFERING POLARITY FOR PURIFICATION AND AQUEOUS INK PREPARATION OF TEXTILE GRADE WATER SOLUBLE DYES
Original Publication Date: 2001-Jun-30
Included in the Prior Art Database: 2004-Apr-09
Xerox Disclosure Journal
Textile grade dyes typically contain significant amounts of excess salts from the dye preparation process. Particularly high-grade dyes are normally utilized to ensure consistently acceptable jetting performance for Thermal Ink Jet (TJJ). The cost and availability of these purified dyes is high and limited. An inexpensive process for removal of the bulk salts that renders the dye dissolved in the preferred organic co-solvent for TIJ aqueous based inks dissolves the crude dyestuff into polar neat solvent. It also adds less polar solvent to drive the last of unwanted salt from the solution and collects the salt-free; dye rich solvent mixed supernatant liquid. Preferred polar organic solvents include formamide and dimethyl sulfoxide (DMSO) with less polar penetrants such as tripropyleneglycol monomethyl ether (TPM) and diethyleneglycol monobutyl ether. Both cationic an anionic dye types are applicable. Solvent mixtures and ratios are tailored for individual dyestuffs. Robust latitude exists for salt removal and dye solubility in a TPWformamide mixture, ie., TPM:formamide = 2: 1 with the same conductivity and tinture for final inks as with a 3: 1 ratio.