Improvements in or relating to the Bleaching of Vegetable and Animal Fibres or other Organic Substances.
Year: 1892

page_text: Date of Application, 11th Mar., 1892
Complete Specification Left, 6th Dec., 1892-Accepted, 11th Mar., 1893
PROVISIONAL SPECIFICATION.
Improvements in or relating to the Bleaching of Vegetable and
Animal Fibres or other Organic Substances.
J, CARL JOHANN EUGEN DE HAEN, Doctor of Philosophy and Royal Counsellor
of Commerce, of List near Hanover, in the Kingdom of Prussia, do hereby declare
the nature of this invention to be as follows:-
Since chemistry has succeeded in producing from common salt by electricity and
very cheaply metallic sodium, greater attention has been paid to the manufacture of
sodium compounds which can only be produced from sodium in the metallic state.
The manufacture of peroxide of sodium has primarily occupied chemists and after
long and tedious experiments excellent results have been obtained.
Peroxide of sodium has been thus introduced into the technical art as a new
oxidizing agent and in particular the bleaching action of the peroxide has been the
object of the present applicant's studies.
The simplest way to employ the peroxide of sodium consists in introducing the
salt into a dilute acid solution and in producing by this means peroxide of hydrogen.
It has been discovered however that, although the solution of peroxide of hydrogen
so obtained and to which is added the corresponding quantity of sodium salt does
bleach, it influences the bleached material in such a manner, as to cause it to lose
its lustre and possess a hard touch.
The effect is quite different, when peroxide of sodium is gradually decomposed by
salts, the oxides of which are capable of being precipitated by sodium, and the use
of magnesia salts has been found particularly suitable for this purpose.
The bleaching process may be carried out in the following manner;
i
A quantity of peroxide of sodium is added to a bath heated to a temperature
of 50° C. and containing magnesia salts, sulphate of magnesia, magnesium chloride etc.
A gradual precipitation of magnesium hydrate then takes place, while the oxygen
of the peroxide of sodium becomes free for the bleaching process.
Immediately after the addition the material to be bleached is introduced into the
bath and treated during about ten minutes at a temperature of 50° C., then a fresh
quantity of peroxide of sodium is added and so on, until the desired result has been
obtained.
A perfect and beautiful bleaching of Tussah silk may be obtained in one and a
half hours and for such an operation a quantity of peroxide of sodium equal to
about 20 to 30% of the weight of the material to be bleached is required, so that
at the present price of peroxide of sodium the cost of the new process is already
below that of bleaching by other agents.
In course of time the cost of peroxide of sodium will become still less and it will
probably be eventually reduced to half its present value, so that the peroxide of
sodium as far as it has to compete with peroxide of hydrogen and of barium will
become the cheapest bleaching agent.
A further reduction of the price is not impossible at all, so that peroxide of
sodium could then successfully compete with chlorine and sulphurous acid also.
As particular advantages of the new bleaching process in comparison with the
use of peroxide of hydrogen may be pointed out ;
1. The quickness of the bleaching action,
2. The excellent lustre and touch of the bleached goods,
3. The strength of the fibre which is by no means reduced by the bleaching
process.
Dotal thin 11th 1
1000

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to the Bleaching of Vegetable and
Animal Fibres or other Organic Substances.
I, CARL JOHANN EUGEN DE HAEN, Doctor of Philosophy, and Royal Counsellor
of Commerce, of List, near Hanover, in the Kingdom of Prussia, 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 the bleaching of vegetable and animal, textile fibres or
other organic substances such as feathers, hair, ivory, bones, sponges, bristles,
leather and the like.
Peroxide of sodium has been introduced for some time into the technical art as a
new oxidizing agent and in particular the bleaching action of the peroxide has been
the object of applicant's studies.
The simplest way to employ the peroxide of sodium consists in introducing the
salt into a diluted acid solution and in producing by this means peroxide of
hydrogen. It has been discovered however that, although the solution of peroxide
of hydrogen so obtained and to which is added the corresponding quantity of sodium
salt does bleach, it influences the bleached stuff in such a manner, that it loses its
lustre and that a hard touch is given to the same.
The effect is quite different, when peroxide of sodium is gradually decomposed by
salts, the oxides of which are capable of being precipitated by sodium oxide, and the
use of magnesia salts has been found particularly suitable for this purpose.
The bleaching process is carried out in the following manner:
A quantity of peroxide of sodium is added to a bath heated to a temperaturo
preferably of 50° C. and containing magnesia salts, sulphate of magnesia, magnesium
chloride etc. A gradual precipitation of magnesium hydrate then takes place, while
the oxygen of the peroxide of sodium becomes free for the bleaching process.
Immediately after the addition, the material to be bleached is introduced into the
bath and treated for about ten minutes at a temperature of say 50° C., then a fresh
quantity of peroxide of sodium is added and so on, until the desired result has been
obtained.
The same effect is obtained, if a mixture of peroxide of sodium with sulphate of
magnesium or other salts, the oxides of which are capable of being precipitated by
sodium oxide, such as calcium,-aluminium,-barium,-strontium,-zinc-etc.,
are brought into water.
salts
A solution of sulphate of magnesia is thus effected and the peroxide of sodium
exercises its bleaching effect on the materials. The idea, that peroxide of magnesia
is formed during this process, is quite erroneous.
In case salts are used, the oxides of which are soluble as hydrates, but insoluble
as carbonates, carbonic acid should be added during the bleaching process.
A perfect and beautiful bleaching of Tussah silk may be obtained in 14 hours
and for such an operation a quantity of peroxide of sodium equal to about 20
to 30% of the weight of the material to be bleached is required, so that at the
present price of peroxide of sodium the cost of the new process is already below
that of bleaching by other agents.
As particular advantages of the new bleaching process in comparison with the
use of peroxide of hydrogen may be pointed out :
1. The quickness of the bleaching action,
2. The excellent lustre and touch of the bleached goods,
3. The strength of the fibre, which is by no means reduced by the bleaching
process

page_text: 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 :-
1. The process of bleaching vegetable and animal textile fibres or other organic
substances (such as feathers, hairs, ivory, bones, sponges, bristles, leather and the
like) by means of peroxide of sodium in a neutral or weak alkaline solution
produced by adding peroxide of sodium to solutions of such salts which contain
oxides capable of being precipitated by sodium hydrate or carbonate of sodium and
as such in the first place magnesium salts such as sulphate of magnesia and
magnesium chloride are to be taken into consideration it being the same thing
whether the peroxide of sodium is introduced into an aqueous solution of these salts
or whether a previously made mixture of peroxide of sodium with sulphate of
magnesia or the other salts mentioned is put into water.
2. In the process described in the first claim the substitution of the magnesium
salts by the calcium-aluminium-barium-strontium-zinc-etc., salts; carbonic
acid being added during the bleaching to salts the oxides of which are soluble as
hydrates but insoluble as carbonates.
Dated this 6th day of December 1892
W. P. THOMPSON & BOULT,
Agents for the Applicant.