Process for Producing Black Azo Dyestuffs on the Fibre.
Year: 1896

page_text: Date of Application, 3th May, 1896-Accepted, 13th June, 1896
COMPLETE SPECIFICATION.
Process for Producing Black Azo Dyestuffs on the Fibre.
I, EMIL RITTER VON PORTHEIM, of No. 38 Ferdinands Strasse, Prague,
Bohemia, Manufacturer, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
My invention relates to a process for producing black azo dyestuffs on cotton
fibre impregnated with ẞ-naphthol sodium. The dyestuffs, produced in the manner
hereinafter described, are distinguished from all similar products hitherto know
by the facility of performing the diazotising operation, the intensity of the tints
produced, the tinctorial power, the resistance to light and the stability of the diazo
compound, whilst the said dyestuffs are not inferior in other respects to any
similar products and therefore they fill up a void in the use of the so-called
ice colours.
The invention is carried out by employing the diazo compounds of the amido
chrysoïdines, such as those formed from the diazo compound of acetyl-p-phenylene-
diamine by its combination with meta-phenylene-diamine or ortho-para-toluylene-
diamine or asymmetrical dimethyl-meta-phenylene-diamine and by disacetylisation
of the obtained product, whether the amido-chrysoïdines are formed as above or in
any other known manner.
In carrying out the diazotising process for the amido-chrysoïdine, 1 molecule of
the latter is treated with 1 molecule of nitrite, but similar results are also obtained
by the action of 2 molecules of nitrite.
The stability of the diazo compounds obtained has been found to increase very
much, when certain acids, such as oxalic acid, are added to these compounds.
EXAMPLE.
5-3 parts by weight of the base of amido chrysoïdine (triamido-azobenzene) are
dissolved in 75 parts by weight of water and 7 parts by weight of hydrochloric acid
(specific gravity 1-2) then 45 parts by weight of ice are added; the cooled
mixture is then diazotised with a concentrated solution of 1.78 parts by weight of
nitrite.
The diazo liquor is mixed with 110 parts by weight of acetic starch paste, then
5-3 parts by weight of oxalic acid are added to it and finally, before printing,
24 parts by weight of acetate of sodium in concentrated solution are added.
The addition of oxalic acid can however also take place before the diazo-
tising operation, that is to say, simultaneously with the addition of hydrochloric
acid.
The mordanting of the cotton fibre can be performed with naphthol-sodium alone,
or with addition of any suitable fatty acid compounds.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
A process for producing black azo dyestuffs on the fibre by the treatment of the
fibre, previously impregnated with ẞ naphthol sodium, with diazo derivatives of the
amido chrysoïdines which are formed in any known manner, as for instance, from
the diazo compound of acetyl-para-phenylene-diamine, by its combination with

page_text: meta-phenylene-diamine or ortho-para-toluylene-diamine or asymmetrical dimethyl-
meta-phenylene-diamine and by the subsequent disacetylisation of the obtained
product, substantially as described.
Dated this 9th day of May 1896
ABEL & IMRAY,
Agents for the Applicant.