Improvements in the Art of Fixing Dyes in Fabrics.
Year: 1896

page_text: Date of Application, 21st Apr., 1896-Accepted, 20th June, 1896
COMPLETE SPECIFICATION.
Improvements in the Art of Fixing Dyes in Fabrics.
I, CHARLES MELBOURNE WHITE of 27 Sonthampton Buildings in the County
of Middlesex, Patent Agent, do hereby declare the nature of this invention, a
communication to me from abroad by the Electro Water-proofing and Dye-fixing
Company, a Corporation organized under the laws of West Virginia in the United
States of America and having its principal place of business at New York City in
the County and State of New York, in the said United States of America, aud in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
The invention consists in fixing dyes in cotton, wool, silk, and other fabrics by
the use of metals and a current of electricity derived either from a battery or from
a dynamo.
It is well known that natural dye stuffs such as log-wood madder, fustic, hypernic
and the like, have to be treated with a mordant to fix them upon the goods
subjected to the dyeing process. The action of the mordant is to form insoluble
"lakes" as they are called in the goods thus leaving the goods dyed at those
portions where the mor aud dye have formed such insoluble "lakes."
This invention relates to the fixing of that class of dyes in which the coloring
principle is in solution in the liquid to which the cloth is subjected and which
coloring principle requires a mordant to fix the same in the goods.
In the practice of this invention such colors are fixed by subjecting the goods to
a current of electricity after they have been run through the solution containing
the coloring principle, the goods being, between a metal plate or roller on the
positive side and having on the other or negativo side a conductor which may be of
the saine metal or some other metal, or may be a carbon plate or roller. The
metal must be connected with the positive current, to wit: that current which
would emanate from the negative element of the battery, or which would be the
positive current coming from a dynamo. The goods are first saturated with the
solution containing the dye, and are then placed between the metal plate or roller
located on the positive side of the goods and a suitable conductor is then placed on
the other or negative side. The current is then passed through the goods and the
water in or on the fibres is decomposed and oxygen is liberated on the positive
plate or roller and hydrogen on the conductor on the negative side. The nascent
oxygen thus liberated forms af oxide of the metal on the positive side, and this
exide enters into chemical combination with the coloring principle contained in
the goode, thus fixing the color as though a mordant had been employed in the
old way.
With different motals different colors or shades can be produced, and different
degrees of color can be obtained by varying the concentration of the dyo liquid and
by the length of time the goods are treated. Thus, if log-wood is employed in a
dilute state, and a tin plate or roller be employed on the positive side, the goods
where the current acts on them will be turned light blue, a more concentrated
solution of the dyeing solution will turn them a darker blue; and still darker with a
greater concentration; and so on till the greatest concentration is reached, which
gives the darkest color. Of course the metallic plate or roller on the positive side
must be insulated from the conductor, which may be carbon or the like, on the
negative side; the goods being treated serving to separate the plates.
As to the amount of current used, it will depend upon the thickness of the goods,
the size of the inachiue and the rapidity with which the operation is to be

page_text: performed. If rapidly rotating pressure rollers are used, the current must have
higher electro-motive force, and be greater in quantity than if more slowly moving
rollers or less pressure be used. It is impossible to state the proper electro-motive
force and quantity of current to be used in all cases; each specific material, the
thickness of the material, and the dye employed, alter the required quantity and
force of current necessary to effect the fixing of the color. The current strength
and quantity is also altered by the pressure between the metal used and the
conductor on the negative side; the greater the pressure the less the current,
and vice versa; if the pressure is great, the period of exposure to the action of the
current is reduced; if the pressure is less, the period of exposure to the current
must consequently be greater. So great a pressure should not be employed as to
squeeze out all the liquid containing the dyeing principle. Any engraved plates or
rollers may be used for this operation. The plate or roller ou the positive side
should have its surface from time to time wiped, in order to remove the excess of
oxide; and also arrangements should be made to absorb the coloring liquid running
off from the lower roll, if the rolls are used. When rolls are used the oxide may
be wiped off by a wiping arrangement bearing permanently on the surface of the
roller connected with the positive current.
The invention differs wholly from the operation described by Goppeleröder, in
which he submitted cloth between conducting plates to the action of a current of
electricity, the cloth having in it a solution of an aniline salt and the other
materials necessary for the production of aniline black. The operation in his case
consisted in oxidizing the aniline salt by the nascent oxygen liberated by the
current, and thus forming the coloring matter in the goods by the operation of the
Baid nascent oxygen, as is done in other aniline processes by the oxidation of
the aniline with arsenious acid, or with nitrobenzole."
"
In this process is produced an oxide of the metal and said oxide is caused to pass
into the goods for the purpose of fixing the dyeing material by forming a "lake
in the fibre of the goods, the fixing of the color, in this invention, being wholly
different from the operation above described wherein the material in the solution,
to wit, the aniline salt, is oxidized by nascent oxygen; besides the natural dye
stuffs which need a mordant are fixed. The process of Goppelsröder produces
aniline colors on the goods by the action of nascent oxygen and from materials
which do not contain any coloring principle in the solution. In this process it is
absolutely essential that a metal be used on the positive side; while in the
Goppelsröder process any conductor, for instance, carbon, can be used on the
positive side as well as a metal, as he merely seeks to liberate nascent oxygen on
the goods at the point or place where the aniline salt is to be oxidized; thus, he
described the use of a carbon pencil.
In the practice of this invention carbon can not be used on the positive side, but
a metal must necessarily be used, as the oxide of the metal is the fixing agent for
the natural color, the said oxide being carried in the direction of the current from
the metallic plate into the fibre. The metals which are best adapted for use on the
positive side are aluminium, tin, zinc, lead, copper, iron and brass. Bismuth and
antimony do not give good results with log-wood, because these metals are not
capable of forming desirable salts with the coloring principle. In general, those
metals work best which form with the coloring principle colored salts.
From the above it will be seen that alloys may be used as well as simple metals
with beneficial results. The selection of the metal to be used on the positive side
will depend upon the natural dye used, and the capacity of that dye to form
insoluble colored sults with the oxide of the metal; and in this regard the old and
well known mordanting process will indicate the best metal to use with any certain
color. In operating on small samples, where the plates used were between two and
three inches in diameter with log-wood, using tin plates, zinc plates and aluminium
plates, a trentment of ten seconds was found to be sufficient to change the yellowish
brown of the log-wood solution into a rich blue, the current being between 20
and 30 volts, and the goods being held firmly between the plates.

page_text: It is impossible to more definitely lay down the amount of current required, as
each case will depend upon the special circumstances attending it, the thickness of
the goods, the dye used and the amount of pressure.
After the goods are thus treated the goods must be well dried in contact with
ordinary air, or other equivalent way. The coloring matter in the untreated
portion of the goods, if such exists, may be removed by washing, if desired, during
the finishing thoreof. If the goods are to have a pattern upon their surface, and
are not to be dyed over all portions, the coloring matter may first be printed
thereon by rollers in the form of a pattern, and the goods can then be subjected to
the action of the current between plain rollers, and the coloring matter will be
fixed wherever the same is in the goods. Those portions of the goods where no
coloring matter exists are not affected so far as dyeing goes. The goods, after the
operation, may be finished as desired. A less satisfactory result may be obtained
by first treating the goods between a metal on the positive side and a conductor on
the negative side, with a current of electricity when the goods are wet and then
subsequently immersing the goods in the dye liquid. A continuous current, in
contradistinction to an alternating current, should be used in carrying out this
invention. An alternating current can be used if like metallic rolls are used on
both sides of the goods.
It is preferred that the dye liquid be fresh, 'for with fresh liquids the result is a
brighter color, the old decoction being more or less oxidized. At times the color
will be the brightest on the negative side. With some dyes the continuation of the
treatment beyond a certain time reduces the intensity of the color, this is found to
be the case with zinc plates and hypernic.
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
olaim is :-
1. The process of fixing dyes upon fabrics which consists in applying the natural
dye in a suitable solvent to the fabric, placing the fabric between an anode of an
oxidizable metal and a suitable cathode, and substantially in contact with the
anode, passing a current of electricity therethrough, oxidizing the anode, and
combining said oxide with the natural dye to form a lake, substantially as
described.
2. The process of fixing natural dyes upon fabrics which consists in applying the
natural dye iu a suitable solvent to the fabric, placing the fabric between and in
contact with an anode of an oxidizable metal and a suitable cathode, passing a
current of electricity therethrough, oxidizing the anode, and combining said oxide
with the natural dye to form a lake, substantially as described.
3. The process of fixing natural dyes upon fabrics which consists in applying the
natural dye in a suitable solvent to the fabric, pressing the fabric between an anode
of an oxidizable metal and a suitable cathode, passing a current of electricity
therethrough, oxidizing the anode, and combining said oxide with the natural dye
to form a lake, substantially as described.
Dated this 21st day of April 1896
WHITE & WOODINGTON,
27 Southampton Buildings, London, Agents.