Improvements in Ungumming and Bleaching by Electrolysis China Grass, Rhea, Ramie, and other Nettles.
Year: 1888

page_text: Date of Application, 12th Sept., 1888
Specification Accepted. 26th Oct., 1888
COMPLETE DI MULTIVALION.
Improvements in Ungumming and Bleaching by Electrolysis China
Grass, Rhea, Ramie, and other Nettles.
I EMILE MARIE HIPPOLYTE ANDREOLI, Journalist of 62 Loughborough Park
Brixton S. W. Surrey, 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 an electro-chemical method for dissolving and removing
the resinous and gummy substances which unite and cement together the decorticated
fibres of the different species of nettles of China Grass Rhea, Rhamie, Bochmeria and
Urtica utilis etc. and to render their fibres white, lustrous, silky flexible and ready for
combing carding spinning and weaving.
Briefly described, this electro chemical process consists in submitting the fibres to
an electric current in an electrolyte of water and chloride of sodium or another
chloride when Hypochlorite of Sodium in combination with Oxygen destroys the
colouring and cementitious or glutinous substances.
It must be understood that I do not undertake to decorticate the stems stalks shoots
of the plant but that on the contrary I only treat the ribbons when they have been
separated from the ligneous part of the plant or stripped of their bark or Cuticle and
are in the state of bundles or fibres which adhere one to the other owing to the gummy
and incrusting substances which form a sort of if not insoluble varnish, at least very
difficult to attack.
Before they are subjected to the electrolytic treatment the long stapled fibres are
tied in bundles at their extremities to keep the fibres parallel and to prevent them
from entangling and mixing up so that the physical and chemical action will be equally
distributed on all parts of the material, and they are placed in openwork trays or
willow trays when they form a layer and such trays are superposed one over the
other in a wooden openwork box or wicker crate so that there is between each tray a
space and that the circulation of the liquid is perfectly free whilst the fibres do not
mix up, which would cause a great amount of difficulty in the work.

page_text: Instead of such layers of fibres in bundles I may attach the bundles by their ends
one to each other so as to form a long rope, which cannot entangle, as it is usual to
do in the cotton mills when the hanks are tied together.
The materials to be bleached are first soaked in water in a tank where the steam
is afterwards gradually introduced in all directions by means of several pipes,
which washes away the soluble matter & facilitates the uniform action of the
subsequent bath on all the parts of the fibrous mass; then a sufficient quantity of
Sodium Carbonate, Caustic Soda or any other alkali is added to make a solution
having a specific gravity of from 1.060 to 1.090 and steaming or boiling during
2 to 3 hours is kept on to disintegrate the bark from the fibre & at the same time to
dissolve the colouring & gummy matters in such a way that after rinsing in a stream
of running water which opens the fibres, separates them & cleans them of extraneous
adhesive substances whether bark or gum which has been acted upon by the
alkaline lye, the Rhea or China grass will be ready to be submitted to the
electrolytic process & rendered white without losing strength or being brittle or
having lost its gloss, and is suitable for textile purposes. The proportions of
Carbonate of soda and Caustic soda may be varied and the detersive properties of
these alkalies may be increased by rendering the liquid more caustic.
The alkaline liquid which has softened & prepared the materials is withdrawn
from the tank which preferably must be closed & water is forced in a spray until
no trace of alkali remains.
I may also take the bundles on which the bark or other extraneous substances
are still slightly adhering & pass them under a strong jet of hot or cold water.
When the materials are very refractory I use a fatty acid such as Oleic or
Margaric Acid in a fluid or saponaceous state which helps the separation of the
bark & cementitious substances which enveloped or glued the fibres together.
At this stage the fibres are still coarse and are far from being perfectly white
and degummed but the alkaline lye has promoted the removal of a great part of
the matters with which the fibres are impregnated and which will be thoroughly
effected by the action of an electric current in a bath of concentrated sea water,
common salt & water or another chloride solution having a density of 10° to 15° T.
I may use a stronger solution but I find that it is far better to bleach in severa!
short operations by means of weak solutions.
The electrodes I use are made of charcoal (see specification Nos. 8161 & 13192
of 1888) I use continuous but preferably alternating currents or I reverse the current
by means of a switch at very short intervals.
When the solution has been sufficiently electrolysed I immerse the crate containing
the layers of material to be bleached & by means of bellows, or better of an
injector disposed in a convenient manner, I force air into the tank to cause the
liquid to circulate freely & rapidly & keep in constant floating motion the fibres
which were cemented together & which not only rapidly turn white but also get
the appearance of fine silky lustrous slender filaments which are strong & will be
ready after washing, for combing, carding & weaving.
1 bleach either in the electrolytic tank containing several sets of electrodes or
in a tank containing the electrolysed solution & with only one anode & one
cathode or in a tank containing the above electrolytic hypochlorite mentioned
liquid and without any electric current at all.
In the first case, the tank is, so to say composed of two parts, a large, wide &
deep one where the material to be treated is, and the second which may be of
the same depth and narrow and which contains a sufficient number of electrodes
to generate the electrolytic hypochlorite of sodium required for the degumming &
bleaching of the nettles. The electrolysis is constantly circulating, sometimes the
materials are between two sets of Electrodes through which passes the current of a
low tension dynamo.
In the second case the electrolysis is supplied from a tank above the bleaching tank
& it is obvious that the nascent Oxygen acts almost as powerfully as if the fibres were
under the action of the current.

page_text: In the third case the operation takes more time. Whatever may be the way in
which the bleaching is carried out, the liquid is constantly renewed & the operation
always takes place in the cold.
The longer the fibres have been in the alkaline bath the easier the electrolytic
treatment is, but I found it advisable to alternate the baths and to use weak solutions
& weak currents in order to have a perfectly snow white fibre which has lost none of
its strength. Therefore instead of having one bath of alkaline lye for say 6 hours
and one chlorinated electrolytic bath for about the same period of time I prefer to
immerse the fibres in an alkaline solution, then in running water and then in the
electrolyte or chlorinated solution & so on in the same alkaline baths and in the saine
electrolyte with less current until all trace of bark or incrusting substances has
disappeared leaving the fibres in a state of division & whiteness which no other
process can reach without decreasing the strength or injuring the fibres.
The final operation is a thorough washing in order to eliminate the Chlorine.
Having now particularly described and ascertained the nature of my said Inven-
tion, and in what manner the same is to be performed I declare that what I
claim is
1st. The bleaching, degumming and eliminating all cuticular or coloring matters
by subjecting the China grass Ramie or Rhea after it has been boiled in an alkaline
lye to an electric current in a solution of Chloride of Sodium or other convenient
chloride as an electrolyte in which the electrodes are made of charcoal as substantially
described.
2nd. The treatment of such fibres in an hypochlorite of Sodium solution which
has been electrolysed and stored, such treatment taking place without passing an
electric current through the solution.
3rd. The use of an electric current as substantially specified in the above described
process.
Dated this Eleventh day of September 1888.