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Conversion of Acid Dyes to Cationic Dyes for Printing Inks

IP.com Disclosure Number: IPCOM000043895D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Gendler, P: AUTHOR

Abstract

Cationic dyes have the desirable property of an affinity for typical mineral sizings found in many papers which renders the cationic dye-sizing interaction product rather intractable. This results in improved waterfastness and even print quality. However, these cationic dyes are, unfortunately, not readily available. A simple, 2-step procedure is now described which converts an existing sulfonated or carboxylated acid anionic dye, to a cationic dye via a sulfonyl chloride followed by treatment with an amine. This conversion is attractive since there are many acid dyes, they come in all colors, they are very well known, and the sulfonate and usually the carboxylate do not influence the chromophore to a large extent so that their conversions should not drastically alter the original color.

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Conversion of Acid Dyes to Cationic Dyes for Printing Inks

Cationic dyes have the desirable property of an affinity for typical mineral sizings found in many papers which renders the cationic dye-sizing interaction product rather intractable. This results in improved waterfastness and even print quality. However, these cationic dyes are, unfortunately, not readily available. A simple, 2-step procedure is now described which converts an existing sulfonated or carboxylated acid anionic dye, to a cationic dye via a sulfonyl chloride followed by treatment with an amine. This conversion is attractive since there are many acid dyes, they come in all colors, they are very well known, and the sulfonate and usually the carboxylate do not influence the chromophore to a large extent so that their conversions should not drastically alter the original color. The process is illustrated for methyl orange (MO)1, a typical azo acid dye. MO is dissolved in tetramethylene sulfone (TMSO), an inert solvent which can dissolve sulfonates, acetonitrile, and treated with phosphoryl chloride (POCl3), a catalytic amount of dimethylacetamide (DMA), and briefly heated. The resulting sulfonyl chloride can be purified, if desired, but was usually combined with the required amine side chain by taking a methylene chloride solution of the crude product and adding the amine. The intermediate, 4-dimethylaminoazobenzene-4'- sulfonyl chloride, is known. We have tested compound 1b and found it to be a...