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IP.com Disclosure Number: IPCOM000006588D
Publication Date: 2002-Jan-16
Document File: 2 page(s) / 42K

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The IP.com Prior Art Database

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US 5370731: PATENT [+3]

Abstract

Ink-jet inks of good pH stability may be prepared from compositions which comprise one or more yellow dyes and one or more buffers. Examples of suitable yellow dyes include are water-soluble azo and bis azo dyes such as C.I. Direct Yellow 86, C.I. Direct Yellow 132, C.I. Direct Yellow 142, C.I. Direct Yellow 173 and C.I. Acid Yellow 23. Examples of buffers include substituted amino compounds, especially aliphatic amines, morpholine derivatives and piperazine derivatives, particularly those which have a sulfonic acid,carboxylic acid or one or more hydroxyl groups.

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DYES AND COMPOSITIONS FOR INK-JET PRINTING

Ink jet printing (“IJP”) is a non‐impact printing technique in which droplets of ink are ejected through a fine nozzle onto a substrate without bringing the nozzle into contact with the substrate. 

There are many demanding performance requirements for dyes and inks used in IJP.  For example they desirably provide sharp, non‐feathered images having good water‐fastness, light‐fastness and optical density.  The inks are often required to dry quickly when applied to a substrate to prevent smudging, but they should not form a crust over the tip of an ink jet nozzle because this will stop the printer from working. The inks should also be stable to storage over time  without decomposing or forming a precipitate which could block the fine nozzle.  An important aspect of storage stability is pH stability as printer heads are susceptible to damage at relatively low pH.

Ink-jet inks of good pH stability may be prepared from compositions which comprise one or more yellow dyes and one or more buffers.  Examples of suitable yellow dyes include are water‐soluble azo and bis azo dyes such as C.I. Direct Yellow 86, C.I. Direct Yellow 132, C.I. Direct Yellow 142, C.I. Direct Yellow 173 and C.I. Acid Yellow 23.  Examples of buffers include substituted amino compounds, especially  aliphatic amines, morpholine derivatives and piperazine derivatives, particularly those which have a sulfonic acid,carboxylic acid or one or more hydroxyl groups.

The preparation and...