Improvements in the Bleaching of Vegetable Textile Materials.
Year: 1891

page_text: Date of Application, 1st Oct., 1891
Complete Specification Left, 28th June, 1892-Accepted, 30th July, 1892
PROVISIONAL SPECIFICATION.
[Communicated from abroad by HERBERT WILLIAM WILSON, of No. 40, Rue de
la Gare, Lille, in the Republic of France.]
Improvements in the Bleaching of Vegetable Textile Materials.
I, OLIVER IMRAY, of No. 28, Southampton Buildings, Chancery Lane, in the
County of London, Chartered Patent Agent, do hereby declare the nature of this
invention to be as follows:-
Usually, in bleaching vegetable textile materials, they are first subjected to the
action of hot alkaline solutions and are afterwards treated with oxidising agents
such as bleaching powder, and these preliminary operations have often to be
repeated, and have to be succeeded by other operations necessary for effecting the
desired decoloration of the material. It has been proposed to employ vacuum and
pressure in order to effect more complete impregnation of the textile materials with
the chemical substances applied to them.
But, hitherto, no practical process has come into use such as that embodied in
the present invention, which has for its object to simplify and abridge these pre-
liminary bleaching operations, to dispense with the heating required in the alkaline
treatment, and to avoid the injury to the material which results from the too vigorous
and often very partial action of the hot alkaline agents. For this purpose, the
textile material, whether in fibre or in the spun or woven condition, is placed dry in a
close vessel from which the air is extracted until the pressure is reduced, it may be
to about one tenth of an atmosphere. A solution of sodium hypochlorite, or
potassium hypochlorite (the former being preferred as it is less costly) at a
temperature considerably below boiling, is then run into the vessel so as com-
pletely to submerge the textile material, and the contents of the vessel are then
subjected to a pressure, it may be of several atmospheres, while the solution is
added to, if necessary, to keep the textile material still submerged. After a short
time, the pressure is relieved, and the material may then be withdrawn from the
vessel and subjected to such farther operations as are usually applied after the
ordinary oxidising treatment. By the process above described, one chemical
operation at low temperature produces the result hitherto requiring the separate
action of alkali at a high temperature and of the oxidising agents which are
afterwards applied.
Dated this 1st day of October 1891.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Bleaching of Vegetable Textile Materials.
I, OLIVER IMRAY of No. 28 Southampton Buildings, Chancery Lane in the
County of London, Chartered Patent Agent, 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:-
Usually in bleaching vegetable textile materials, they are first subjected to a
process of boiling with alkaline solutions, and are afterwards treated with oxidising
agents such as a solution of bleaching powder, and this succession of operations has
often to be repeated in order to effect the desired decoloration of the material. It
has been proposed to employ vacuum and pressure, either alone or as successive
treatments, in order to effect more complete impregnation of the textile materials
[Price 8d.1

page_text: with the chemical substances applied to them. But hitherto no practical process
has come into use such as that embodied in the present invention, which has for its
object to simplify and abridge the bleaching process, to dispense with the heating
required in the alkaline treatment, and to avoid the injury to the material which
results from the too vigorous and often very partial action of the hot alkaline
agents. For this purpose, the textile material, whether in fibre or in the spun or
woven condition, is placed dry in a close vessel from which the air is extracted
until the pressure is reduced, it may be to about one tenth of an atmosphere. A
solution of sodium hypochlorite or potassium hypochlorite (the former being
preferred as it is less costly) at a temperature considerably below boiling is then
run into the vessel so as completely to submerge the textile material, and the
contents of the vessel are then subjected to a pressure, it may be of several
atmospheres, while fresh solution is, if necessary, added to keep the textile material
still submerged. A good solution for the purpose may be prepared as follows:
5 parts bleaching powder and 3 parts soda ash are mixed in solution and, the clear
solution being decanted off, the precipitate is diluted with water to a specific
gravity of from 1-03 to 101. The temperature under which the bleaching process
is carried out may be from 50° Fahr. upwards, but for most purposes not exceeding
100° Fahr. The temperature as well as the strength of the solution may be varied
within the limits mentioned, or even in certain cases outside these limits, to suit the
various characters of the materials treated and of the bleaching required. When a
considerable quantity of material is treated, it is of advantage to keep the liquor in
circulation while the pressure is maintained. After a sufficient time, usually from
one to two hours, the pressure is relieved and the material may then be withdrawn
from the vessel and subjected to such farther operations as are usually applied after
the ordinary oxidising treatment. By the process above described, one chemical
operation, at low temperature, produces the result hitherto requiring the separate
action of alkali at a high temperature and of the oxidising agents which are
afterwards applied.
By employing vacuum and pressure, as above described, the solution is caused to
penetrate the ultimate fibres completely so that, without requiring heat, it effects
oxidation of the natural colouring matters and other constituents, not of the
character of cellulose, which are removed as soluble compounds in combination with
the alkali.
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 :
The herein described process of bleaching textile materials by subjecting them,
under vacuum and pressure to the action of alkaline hypochlorites, substantially as
described.