Improvements in the Manufacture of Alizarin Colours and in the Method of Employing same in the Process of Dyeing.
Year: 1891

page_text: Date of Application, 18th Nov., 1891-Accepted, 19th Dec., 1591
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Alizarin Colours and in the
Method of Employing same in the Process of Dyeing.
"
I, HENRY NICHOLAS FREDERICK SCHAEFFER, of Merrimack House, Lowell,
Massachusetts, United States of America, Chemist, do hereby declare the nature
of the said invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
This invention relates to the production of a soluble modification of alizarin, with
which colors or lakes similar to those produced by the combination of a mordant
with the ordinary insoluble alizarin, may be formed in an improved manner.
By experiment I have discovered that by treatment of alizarin with a soluble
borate, a definite soluble compound is produced, which contains the alizarin in
combination with both the boracic acid and the base, and thus forms a soluble salt
of a compound acid radical, and from which soluble salt the alizarin is easily sepa-
rated and precipitated by contact with a mordant, a reaction which does not occur
when alizarin in combination with an alkali (such as when combined with soda, as
alizarate of soda) is caused to act upon a mordant.
The soluble modification or compound of alizarin referred to, may and preferably
will be obtained in the following manner, viz. :-
The commercial alizarin which is prepared in the form of a paste (i.e. in an
hydrated form) is preferably completely dried, and one part by weight of the
dehydrated substance is thoroughly incorporated or mixed, as by trituration,
with two parts by weight of a dry soluble borate, preferably common borax or
sodium borate.
To this mixture, water, preferably heated to the boiling point, is added, and a
perfect solution of the alizarin and borate is obtained, which solution is then
available for application to the fibre or fabric to be treated.
The solution of the alizarin and borate may and preferably will be evaporated
to dryness, and the powder so produced may be put in suitable packages for trans-
portation or storage until ready for use.
The powder being perfectly soluble in cold water and immediately so in hot
water, a solution for use may be readily prepared at any time.
The soluble product of the alizarin with the borate, which I believe to be
the boro-alizarate of the alkali, is unstable, and differs from the ordinary well
known solutions of alizarin in alkalies, which are stable in that any sub-
sequent combinations of the alizarin with mordants are not influenced or affected
by the presence of the borates as they are by the presence of such alkalies,
that is, the alizarin of the boro-alizarate retains its property of dyeing and
readily unites with a mordant to produce a practical or desired colour or lake,
of a shade equal and usually superior to the color or lake produced with insoluble
alizarin.
By means of the boro-alizarate or soluble alizarin referred to, the ordinary pro-
cesses for the production of lakes in dyeing with alizarin, may be very considerably
simplified and improved for by reason of the solubility of the alizarin product in
water, the fibre may first be completely saturated with the coloring matter, that
is the soluble alizarin, and the required lake or color may then be produced within
the fibre by the subsequent application of the necessary mordant, thus reversing
the ordinary methods of dyeing with alizarin for the production of such lakes,
which essentially consists in the application of the mordanting bodies usually a
lengthy and difficult operation, either in whole or in part previous to the application
of the alizarin.
The colors or lakes produced by the combination of the soluble alizarin with a
mordant, are superior to the colors ordinarily produced from the combination of

page_text: alizarin and a mordant, because the fibre or fabric by reason of the solubility in
water of the boro-alizarin compound, is thereby completely saturated with or per-
meated by the coloring matter, and the lakes or colors formed by the combination
of the coloring matter with the mordant are in consequence fixed on and within
such fibre or fabric, while at the same time there is a great economy in the quantity
of the coloring matter required to produce a certain shade or result.
Owing to the complete saturation of the fibre or fabric, the colors or lakes
produced possess a greater depth or solubility and usually greater brilliancy,
than the ordinary colors or lakes produced by the present known methods of
dyeing with alizarin.
By the term alizarin in the foregoing, I mean to include, not only natural and
artificial alizarin proper, having the formula C₁H.O, but also such similar bodies
known to the chemist as anthrapurpurin, flavo-purpurin, iso-purpurin, etc. with their
homologues and derivatives.
I prefer to render the alizarin soluble in water as above described, but I do not
desire to limit myself in this respect, as the soluble salt of the compound acid
radical may be obtained in other ways.
For instance, the alizarin in paste form, or preferably in an anhydrous condition,
may have added to it crystallized boracic acid, which is thoroughly mixed or
incorporated with the alizarin.
A solution of alkali (that is of potassium, sodium or ammonium) preferably
warin, is then added, and the alizarin is rendered soluble by the formation of a
soluble borate of the alkali.
Instead of adding a warm solution of alkali, the latter may be cold when added
and the reaction completed by heat.
On account of this solubility of the new alizarin compound, animal and vegetable
fibres, either raw or in any stage of manufacture, may be readily dyed to any
desired shade or depth of color by the processes above indicated.
With the herein described soluble alizarin, a solution of alizarin of any desired
degree of concentration or strength may be obtained, and in dyeing, any desired
shade of alizarin color from the deepest, such as garnet, Turkey red, etc. to the
lightest, such as the pinks, may be produced.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The herein described method of dyeing or producing colors or lakes with
alizarin, which consists in first treating the cloth or fibre with a soluble modification
of alizarin, consisting of a soluble salt of boracic acid combined with alizarin, and
then with a mordant, substantially as described.
2. The herein described soluble alizarin coloring matter consisting of a soluble
salt of alizarin and boracic acid capable of producing any desired shade of the
alizarin colors from the deepest to the lightest, substantially as described.
3. The herein described anhydrous boro-alizarate of a soluble alkali or soluble
alizarin powder, consisting of an anhydrous soluble salt of alizarin, boracic acid
and a soluble alkali capable of producing any desired shade from the deepest to
the lightest of the alizarin colors, substantially as described.
4. The method of producing a soluble alizarin capable of contbining with a
mordant to obtain any desired or required shade of the alizarin colors, which
consists in combining alizarin with a soluble salt of boracic acid substantially in
the manner set forth.
Dated this 6th day of November 1991.
H. N. F. SCHAEFFER.
W. H. Beck,
Per F. G. Gunyon,
115, Cannon Street, London; E.C., Agent.