Organic compounds -- part of the class 532-570 series – Organic compounds – Azo
Patent
1996-12-16
1998-10-20
Powers, Fiona T.
Organic compounds -- part of the class 532-570 series
Organic compounds
Azo
106 3148, C09B 2908, C09D 1100
Patent
active
058247858
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/GB96/00300 filed Feb. 5, 1996.
FIELD OF THE INVENTION
The present invention relates to dyes and aqueous Ink compositions 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 non 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. Non reactive dyes of this kind have been described in U.S. Pat. No. 4,771,129 (K. Hideo) and U.S. Pat. No. 4,777,248 (D. Greenwood). In particular dyes of the following structural formulas have been described: ##STR1##
In some of these dyes particularly enhanced water-solubility has been claimed to be due to the introduction of elements of the following structure ##STR2## and in some cases water solubility seems still to be improved by introduction of elements of the structure
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 are 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 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 (4) ##STR3## wherein: R.sub.1 is selected from hydrogen or an aliphatic radical having from 1 to 6 C atoms; to 6 C atoms, C2 to C6 substituted alkyl where the substituents are selected from OH, OCH.sub.3, COOM, SO.sub.3 M; aralkyl; unsubstituted aryl or an aryl substituted by COOM or SO.sub.3 M; atom; substituted alkyl where the substituents are selected from OH, OCH.sub.3, COOM, SO.sub.3 M; from 1 to 6 C atoms; where the substituents are selected from CN, COOM, OH, COOCH.sub.3, COOCH.sub.2 CH.sub.3, COCH.sub.3 ; unsubstituted aryl or aryl substituted by CH.sub.3, halogen; 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 prin
REFERENCES:
patent: 4777248 (1988-10-01), Greenwood
Baettig Kurt
Jan Gerald
Ilford Imaging Switzerland GmbH
Powers Fiona T.
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