A NEW METHOD OF DYEING SILK AND WOOLLEN FIBRES WITH INSOLUBLE AZO-COLOURING MATTERS
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
WO, DAN DAWSON, of Hofmann Street, Milnsbridge, near Huddersfield, Yorkshire,
Chemist, and GEORGE WILLIAM OLDILAM, of Netherton, near Huddersfield, aforesaid,
Silk Dyer, do hereby declare the nature of our invention for "A NEW METHOD OF
DYEING SILK AND WOOLLEN FIBRES WITH INSOLUBLE AZO-COLOURING MATTERS,”
to be as follows :—
This invention has special reference to dyeing silk fibre (but it is also applicable
to dyeing woollen fibre) with insoluble azo-coloring matters simultaneously with
their formation. In the course of experiments we have found that when precipi-
tated naphtol or a similar body is added to a weak neutral solution of a diazo body,
a bath is produced which has a tendancy to slowly and gradually deposit an azo-
coloring matter. The same effect is also produced, but at a slower rate, if the bath
contains a very slight excess of a weak organic acid, as for example, acetic acid.
If silk or wool is immersed in such a bath the fibre will induce formation of the
coloring matter upon its surface and become dyed thereby.
As an example of preparing a bath according to our invention for dyeing silk or
woollen fibre we proceed as follows:-
We azotize a body, say, for example zylidine by adding in the usual way nitrite
of seda to a weak solution containing, say, point one per cent of the hydrochlorate
of this base, together with a somewhat large excess of hydrochloric acid until the
base becomes thoroughly azotized, then an emulsion of pure chalk is added until
completo neutralization is attained, after which naphtol is added in a finely precipi-
tated state in at least equivalent proportion to the zylidino employed along with
acetate of soda, and a slight quantity of acetic acid.
The finely precipitated naphtol and acetato of soda are obtained together by
precipitating naphtol from naphtolato of soda by means of acetic acid, the acid
being added slightly in excess. Silk or wool, but more especially silk, immersed
into a bath prepared as mentioned above will gradually fix upon itself the coloring
matter as it forms, and thereby become effectively dyed, the rate of formation
being regulated by introducing into the bath a larger or smaller quantity of acetic
acid or similar acid.

page_text: The following are some of the bodies which may be azotized and employed in
the same manner as the example previously cited-viz-aniline, toluidine, zylidine,
naphtylamine, amidoazobenzole, and roscaniline, all of which give colors by the
same treatment; but doubtless there are many other compounds containing
amidogen which will act in the same way.
The quantity of materials used for the purposes herein mentioned will vary
according to depth of color or shade required as will be well understood by chemists
and dyers.

page_text: COMPLETE SPECIFICATION,
We, DAN DAWSON of Hofmann Street, Milnsbridge, near Huddersfield, Yorkshire,
Chemist, and GEORGE WILLIAM OLDHAM of Netherton, near Huddersfield aforesaid,
Silk Dyer do hereby declare the nature of our invention for "A NEW METHOD of
DYEING SILK AND WOOLLEN FIBRES WITH INSOLUBLE AZO-COLOURING MATTERS" and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:—
This invention has special reference to dyeing silk fibre, (but it is also applicable
to dyeing woollen fibre) with insoluble azo-colouring matters, simultaneously with
their formation.
In the course of experiments, we have found that when precipitated naphtol or a
similar body is added to a weak neutral solution of a diazo body, a bath is produced
which has a tendancy to slowly and gradually deposit an azo-colouring matter.
The same effect is also produced, but at a slower rate, if the bath contains a very
slight excess of a weak organic acid, as for example, acetic acid. If silk or wool is
immersed in such a bath, the fibre will induco formation of the colouring matter
upon its surface, and become dyed thereby.
As an example of preparing a bath according to our invention for dyeing silk or
woollen fibre, we proceed as follows.
We azotize a body, say, for example, zylidine or naphtylamine, by adding in the
usual way, nitrite of soda to a weak solution containing, say, decimal, one per cent
of the hydrochlorate of this base, together with a somewhat larger excess of hydro-
chloric acid until the base becomes thoroughly azotized, then an emulsion of pure
chalk is added until complete neutralization is attained, after which naphtol is
added in a finely precipitated state in at least equivalent proportion to the zylidine
or naphtylamine employed, along with acetate of soda, and a slight quantity of
acetic acid.
The finely precipitated naphtol and acetate of soda are obtained together by
precipitating naphtol from naphtolate of soda by means of acetic acid, the acid
being added slightly in excess. Silk or wool, but more especially silk, immersed
into a bath prepared as mentioned above, will gradually fix upon itself the
colouring matter as it forms, and thereby become effectively dyed; the rate of
formation can be regulated by introducing into the bath a larger or smaller
quantity of acetic acid or similar acid.
The following are some of the bodies which may be azotized and employed in
the same manner as the examples previously cited-viz-aniline, toluidine, zylidine,
amidoazobenzole, and roseaniline, all of which give colours by the same treatment;
but doubtless there are many other compounds containing amidogen which will act
in the same way.
The kind of colour produced by this process depends upon the kind of base
made use of to be azotized-for instance, aniline yields orange, zylidine scarlet, and
naphtylamine red,

page_text: The quantity of materials used for the purposes herein mentioned, will vary
according to depth of colour or shade required as will be well understood by
chemists and dyers.
When silk or wool has been thus dyed it must be well washed in water, after
which it is advisable to work it in a hot soap solution, or put through any other
cleansing process, whereby the colour will be considerably improved.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is
The means or method of fixing upon silk and wool (but especially silk) at one
operation insoluble azo-colouring matters, in which the bodies employed are so
balanced as to cause the dyeing process to proceed in one bath, slowly and gradually,
according to the rate of formation of the colouring matter.