Organic compounds -- part of the class 532-570 series – Organic compounds – Azo
Patent
1996-12-16
1997-11-04
Powers, Fiona T.
Organic compounds -- part of the class 532-570 series
Organic compounds
Azo
534728, 106 22K, C09B 4316, C09D 1100
Patent
active
056841400
DESCRIPTION:
BRIEF SUMMARY
This is a 371 of PCT/GB96/00262 filed Feb. 5, 1996.
FIELD OF THE INVENTION
The present invention relates to dyes and aqueous ink composition comprising these dyes for ink jet printing processes.
Ink jet printing systems generally are of two types: continuous stream and drop-on-demand. In continuous stream ink jet systems, ink is emitted in a continuous stream under pressure through an orifice or nozzle. The stream is perturbed, causing it to break up into droplets at a fixed distance from the orifice. At the break up point, the droplets are charged in accordance with digital data signals and passed through an electrostatic field which adjusts the trajectory of each droplet in order to direct it to a waste ink collecting vessel (e.g. for recirculation) or a specific location on a recording medium. In drop-on-demand systems, a droplet is expelled from an orifice to a position on a recording medium in accordance with digital data signals. A droplet is not formed or expelled unless it is to be placed on the recording medium.
The most important part of an ink used in ink jet printing are the dyes. Although a number of dyes have been proposed none has been produced which meets all the requirements of a modern printing process.
BACKGROUND OF THE INVENTION
Reactive dyes with incorporated 1,3,5-triazine structural elements are common in textile printing and have also been proposed for ink jet printing. Such dyes are for several reasons in general not too well suited for this application. The reactive groups are not very stable over prolonged periods in aqueous solutions. Dyes containing such reactive groups are moreover, due to their potential health risk, less suitable for handling in a non industrial environment.
Reactive dyes of this kind have been described in EP 559'331 (B. Lamble et al). In particular dyes of the following structural formulas have been described: ##STR1##
These dyes are however still inadequate when used in aqueous inks of modern ink jet printers. In particular printers of the continuous-stream type are highly demanding as far as physical properties of the inks are concerned. Particularly critical is the storage stability of the inks without forming degradation products prone to clog the nozzles of the printer. Printers are today able to print images of high density rapidly. Therefore highly concentrated inks are needed in order to avoid the jetting of high water volumes onto the receiving layer. These high concentrations should ideally, for environmental reasons, be achieved without the use of organic cosolvents. Such inks can only be prepared with dyes having a particularly high water solubility.
Dyes of the above mentioned structures which are the state of the art, are in general not soluble or stable enough to satisfy the required demanding conditions. It is the aim of this invention to provide dyes with the required high water solubility.
DESCRIPTION OF THE INVENTION
This invention relates to azo dyes of the formula (3) ##STR2## wherein: R.sub.1 is selected from hydrogen or an aliphatic radical having from 1 to 6 C atoms; or acylamino containing up to 3 C atoms; to 6 C atoms, substituted alkyl having 2 to 6 C atoms where the substituents are selected from OH, OCH.sub.3, COOM, SO.sub.3 M; aralkyl; unsubstituted aryl or an awl substituted by COOM or SO.sub.3 M; R.sub.5 and R.sub.6 may form a ring without or with inclusion of a hetero atom; atoms; substituted alkyl having 2 to 6 C atoms where the substituents are selected from OH, OCH.sub.3, COOM, SO.sub.3 M; from 1 to 6 C atoms; 4,8/5,7/6,8/3,6,8 or 4,6,8. In a case where m is 1, SO.sub.3 M may also be in position 1 or 4to 8; alkyl, alkoxyalkyl and hydroxyalkyl each having 1 to 12 C atoms.
The azo dyes of the present invention comprise no reactive groups. They are of particular use in inks used for ink-jet printing because of their high water solubility.
Dye Synthesis
One method of preparing dyes of the present invention is by: ##STR3## with cyanuric chloride under conditions such that one chlorine atom of the triazine is displ
REFERENCES:
patent: 3843623 (1974-10-01), Siegel
patent: 4661158 (1987-04-01), Kobayashi et al.
Baettig Kurt
Jan Gerald
Ilford A.G.
Powers Fiona T.
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