Improvements in the Bleaching of Fibre.
Year: 1889

page_text: Date of Application, 9th Jan., 1889
Complete Specification Left, 9th Nov., 1889-Accepted, 4th Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Bleaching of Fibre.
I ALFRED GORDON SALAMON of 1 Fenchurch Avenue in the City of London,
Analytical Chemist, do hereby declare the nature of this invention to be as
follows:-
:-
This invention has for its object the bleaching of vegetable fibre after suitable.
preliminary treatment of the fibre with alkaline solutions, without the use of
chlorine.
The preliminary treatment to which I subject the fibre is intended to achieve the
double object of cleansing the fibre and of rendering it more amenable to to the action
of the bleaching agents which I subsequently employ. This treatment consists in
first boiling the material in the manner usual with bleachers, in a kier or other suitable
vessel in which is contained a solution of caustic alkali, preferably soda. The strength
of this solution, and the length of time during which the fibre is allowed to be in
contact with it, should be proportionate to the foulness of the fibrous material.
The material is taken out of this bath, and washed by convenient means until
sufficiently free from alkali.
The materials I employ as my bleaching agents are two, and are made up in two
separate baths. One bath contains a solution, suitably concentrated, of permanganate
of soda. The other a solution of borax of convenient strength, more or less saturated
with sulphurous acid. The borax solution is impregnated with sulphurous acid by
any convenient means, and the amount of impregnation necessary or advisable will
be dependent upon the character of the fibre it is desired to bleach; but in no case
should the solution of borax be completely saturated with sulphurous acid.
The fibrous material, treated as above described with caustic alkali, is first placed
in the bath of sodic permanganate, and allowed to remain there for about fifteen
minutes, whereby a brownish film or deposit is formed on the fibre, which probably
consists mainly, if not entirely, of hydrated oxide and peroxide of manganese.
The fibrous material is next taken out of the permanganate bath, and immediately
introduced into the second bath containing borax and sulphurous acid, where it is
allowed to remain until the oxides of manganese have been dissolved off the fibre,
and until the sulphurous acid has effectually completed the bleaching operation, so as
to adapt the fibrous material to practical requirements.
The fibrous material is then taken out of the bath of borax and sulphurous acid;
and is then ready, after efficient washing, to be put through the finishing operations
customary in bleaching by the chlorine process.
The permanganate of soda I prefer to prepare through the green coloured salt
known as manganate of soda. The latter is a comparately cheap compound, which
may be prepared with facility in quantity suitable for all requirements of the process.
It is made in the usual way, by fusing peroxide of manganese with sodic hydrate or
nitrate. The green manganate of soda thus formed is then dissolved in water, whereby
it is decomposed, when the water is added in sufficient quantity, with formation of
permanganate of soda and precipitation of manganese dioxide. Manganate of soda
is a very alkaline salt when in solution; so much so, that it might require very
great dilution in order to fit it for the purposes of fibre bleaching. I therefore prefer,
after filtering or syphoning off, if necessary, the manganate of soda, after treatment
with water, to acidify the solution to form the permanganate of soda. Or the
decomposition may be effected by any other suitable and known method.

page_text: The borax bath is made by saturating a solution of borax with sulphurous acid
gas generated by any convenient method, and subsequently diluting to any required
strength.
NEWTON & SON,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Bleaching of Fibre.
I, ALFRED GORDON SALAMON, of 1 Fenchurch Avenue, in the City of London,
Analytical 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 has for its object the bleaching of vegetable fibre, after suitable
preliminary treatment of the fibre with alkaline solutions, without the use of chlorine.
The preliminary treatment to which I subject the fibre is intended to achieve the
double object of cleansing the fibre, and of rendering it more amenable to the action
of the bleaching agents which I subsequently employ.
This treatment consists in first boiling the material, in the manner usual with
bleachers, in a Kier or other suitable vessel, in which is contained a solution of caustic
alkali, preferably soda.
The strength of this solution, and the length of time during which the fibre is
allowed to be in contact with it, should be proportional to the foulness of the fibrous
material. The quantity of alkali added should be the same as that employed in the
ordinary process of bleaching.
The material is next taken out of this bath, and washed by, convenient means until
sufficiently free from alkali, such sufficient freedom being indicated in the ordinary
way, either by taste or by the use of litmus paper.
The materials I employ as my bleaching agents are two, and made up in two
separate baths. One bath contains a solution, suitably concentrated, of permanganate
of soda. The other a solution of borax of convenient strength, more or less saturated
with sulphurous acid. The borax solution is impregnated with sulphurous acid, by
any convenient means, and the amount of impregnation necessary or advisable will
be dependent upon the character of the fibre it is desired to bleach; but in no case
should the solution of borax be completely saturated with sulphurous acid. The
fibrous material, treated as above described with caustic alkali, is first placed in the
bath of sodic permanganate, and allowed to remain there for about 15 minutes,
whereby a brownish film or deposit is formed on the fibre, which probably consists
mainly, if not entirely, of hydrated oxide and peroxide of manganese.
The strength of this bath of permanganate of soda is best arrived at by dissolving
about eleven pounds of permanganate of soda in about 265 gallons of cold or lukewarm
water, or by making a solution by other means, which, when chemically tested by
known means, will give about this proportional strength. The quantity of perman-
ganate of soda mentioned, namely, about eleven pounds (avoirdupois), is about the
quantity required to treat one ton of raw material. The fibrous material is next taken
out of the permanganate of soda bath, and immediately introduced into the second
bath containing borax and sulphurous acid, where it is allowed to remain until the
oxides of manganese have been dissolved off the fibre, and until the sulphurous acid
bas effectually completed the bleaching operation, so as to adapt the fibrous material
to practical requirements.
The bath of borax and sulphurons acid is prepared by dissolving about three pounds
of borax in about twenty gallons of water, and then passing sulphurous acid gas or
solution into the water, until it smells strongly of sulphurous acid.gas.

page_text: The fibrous material is then taken out of the bath of borax and sulphurous acid, and
is then ready, after efficient washing, to be put through the finishing operations
customary in bleaching by the chlorine process.
The permanganate of soda 1 prefer to prepare through the green coloured salt
known as manganate of soda. The latter is a comparatively cheap compound, which
may be prepared with facility in quantity suitable for all requirements of the process.
It is made in the usual way by fusing peroxide of manganese with sodic hydrate or
nitrate. The green manganate of soda thus formed is then dissolved in water, whereby
it is decomposed, when the water is added in sufficient quantity, with formation of
permanganate of soda and precipitation of manganese dioxide. Manganate of soda
is a very alkaline salt when in solution; so much so, that it might require very great
dilution in order to fit it for the purposes of fibre bleaching.
I therefore prefer, in the preparation of permanganate of soda, after filtering, or
syphoning off if necessary, the manganate of soda, suitably diluted with water, to-
acidify the solution to form the permanganate of soda, or the decomposition may be
effected by.any other suitable and known method.
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 :-
The process of bleaching vegetable fibre by the combined use of Permanganate of
Soda, Borax, and sulphurous acid, substantially as described.
Dated this 9th day of November 1889.
NEWTON & SON,
Agents for the Applicant.