Process of Mordanting Animal Fibre.
Year: 1897

page_text: Date of Application, 18th Dec., 1897-Accepted, 29th Jan.,
1898
Process of Mordanting Animal Fibre.
I, OTTO PAUL AMEND, of 205, Third Avenue, in the City and State of New York,
United States of America, Chemist, 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:-
This invention relates to a process of mordanting animal fibre, whether wool
fibre, silk fibre, hair or other animal fibre and it consists of the steps hereinafter
set forth.
In carrying out this process I first treat the fibre with an acid in dilute state.
This step in the process admits of the use of any suitable acid which will not
reduce chromic acid, such as oxalic acid, sulphuric acid, acetic acid, muriatic acid,
nitric acid, etc. Any one of such dilute acids will produce upon the fibre the effect
desired, although not always in the same degree of desirability or with the same
facility and cheapness. We prefer to use, in this step, an oxalic acid solution of
about one-tenth of one per cent. (.001) and find the acid solution most effective at
a temperature of about 125° Fahrenheit, in which the fibre remains for about half
an hour. The strength of the dilute acid, its temperature, and the length of time
the fibre is subjected thereto, may of course be considerably varied without depart-
ing from the scope of the invention. It will be found, however, that the fibre will
require longer treatment in the dilute acid if its temperature is reduced and that a
stronger dilute acid will act at a lower temperature. The temperature of the dilute
acid might be raised considerably above 125° Fahrenheit and might even be
brought to boiling temperature without departing from the invention. But boiling
would be injurious to the fibre and would not be recommended in practice. For a
continuous, rapid and practical carrying out of the process I have found that the
strength, temperature and duration of the bath, as above stated, are quite satisfac-
tory, that is to say, the bath being in solution of about one-tenth of one per cent.
in strength, at about 125° Fahrenheit, and about half an hour in duration.
In the second step of the process the fibre is treated for about half an hour in
a bath consisting of a chromic acid solution of suitable strength, as for example,
about one-thirtieth of one per cent. (.00033) of chromic acid. The temperature of
this second bath should be such that the fibre under treatment will not be substan-
tially oxidized. In practice, I prefer to make the first bath in the form of an
aqueous solution (in contradistinction to a gaseous form which might be used), and
the chromic acid is added to the acid solution of the first step, and at this time the
temperature of the bath will have become somewhat lower. If the bath of the first
step is not raised above 125° Fahrenheit, as is recommended, the bath will have
become somewhat lower than this temperature when the chromic acid is added.
This temperature will be quite satisfactory.
In the third step I add to the chromic acid bath of the second step any suitable
reducing agent, which may be either metallic or non-metallic in character. A two-
tenths of one per cent. (.002) solution of bisulphite of soda has been used with suc-
cess as the reducing agent. In this reducing bath the fibre is treated for about half
an hour. The temperature of the bath during this third step will in practice be

page_text: lower than that of the chromic acid bath, which will have already cooled somewhat.
The temperature of the bath during this third step might, however, be considerably
varied either way, without departing from the invention. But it should not be
raised to such a point as would cause the fibre to be oxidized, so as to substantially
affect the fibre.
Upon the fibre thus mordanted there will be found to remain a certain amount
of acid or acids from the reducing bath which is apt to produce deleterious effects
in the subsequent dye bath. The fourth step of the process is designed to remove
or render removable such remaining acid or acids from the fibre, so as to obviate
these deleterious results.
In this fourth step of the process the fibre is treated in a wash bath containing
a suitable neutralizing agent which by acting upon the acid or acids remaining
apon the fibre after the third step, renders it or them easily removable. In prac-
tice, the mordanting liquor is run off and the wash bath for the fibre is run in for
the fourth step. Any neutralizing agent suitable for neutralizing the acid or acids
of the reducing bath may be employed for the purpose.
of a carbonate of soda solution of about two-fifteenths of one per cent. (.00133) is
A wash bath consisting
quite efficient for this purpose.
Any other suitable neutralizing agent may of course be employed. If desired,
ammonia or lime water may be used as the neutralizing agents. The fibre is sub-
jected to the wash bath for about half an hour, which is gradually raised from
room temperature to about 140° Fahrenheit. The fibre is then ready for the dye
bath.
The temperatures at which the fibre is treated and the duration of the various
steps may be considerably varied without departing from the invention.
The duration of the treatment of the fibre for the several steps is, in general,
dependent upon the temperature and strength of the bath and the nature of the
fibre. The time of treatment would be longer for lower temperatures and weaker
solutions and shorter. for higher temperatures and stronger solutions, other things
being equal.
:
This process as above described has been found to be peculiarly efficient in
working with unscoured fibre, that is, fibre from which the natural oil and fat has
not been removed. This peculiarity of the process renders it specially valuable in
dyeing wool fibre. Heretofore it has been the practice to scour the wool fibre be-
fore, mordanting it, in order to remove from the fibre the natural oil and fat whose
presence on the fibre made mordanting of unscoured wool by the previous methods
employed difficult and generally impracticable.
directed to the discovery of a mordanting process which could be efficiently
For years efforts have been
employed on unscoured wool fibre. Such a process, it has been recognized, would
be of great value both because of the great saving in time, labor, and the cost of
materials which would be made by working with unscoured wool fibre and also
because of the saving in the strength and quality of the fibre which the retention
of its natural oil and fat would entail. Prior to this invention, however, no
mordanting process has been employed for unscoured wool fibre, so far as I am
aware. My process, however, is applicable to both scoured and unscoured fibre.
In carrying out my process for scoured animal fibre, I may omit the first step
consisting of the acid treatment, above described, and still obtain many of the
benefits of my mordanting process. But this acid treatment should not be omitted
when working with unscoured wool, and it is preferably used when working with
other unscoured animal fibres. Moreover, in working with scoured fibre, when this
first step is omitted, I may use with advantage, in the chromic acid bath, a per-
centage of such acids as are used to form the first bath, that is, such acids as will
not reduce the chromic acid. Such acid assists in the fixation of the chromic acid
on the fibre and in its subsequent reduction. I have successfully used; in the
chromic acid bath, oxalic acid of about one tenth of one per cent. (0.001) in relation 5
to the solution.
Again, in some cases when working with fibre which has been subjected to the

page_text: some
treatment of the first step, I may dispense with the treatment by the neutralizing
agent which constitutes the fourth step as above described; and yet obtain
of the advantages of the process. But in general this treatment by the neutraliz-
ing agent should be employed as it will be found beneficial.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
1. The process of producing a mordant on animal fibre which consists in, first,
treating the fibre with a chromic acid solution at such temperature as will not sub-
stantially oxidize the fibre; second, treating the fibre with a reducing agent, and
third, treating the fibre with a neutralizing agent for the purpose of removing or
rendering removable from the fibre the injurious acid or acids remaining thereon
from the reducing bath.
2. The process of producing a mordant on animal fibre which consists in, first,
treating the fibre with a suitable dilute acid which will not reduce chromic acid;
second, treating the fibre with a suitable chromic acid solution at such temperature
as will not substantially oxidize the fibre, and third, treating the fibre with a suit-
able reducing agent.
3. The process of producing a mordant on animal fibre which consists in, first,
treating the fibre with a suitable dilute acid which will not reduce chromic acid;
second, treating the fibre with a suitable chromic acid solution at such temperature
as will not substantially oxidize the fibre; third, treating the fibre with a suitable
reducing agent; and fourth, treating the fibre with a suitable neutralizing agent.
Dated this month dow of Dogambar 1807