A Process Ior washing Crude wool.
Year: 1895

page_text: Date of Application, 1st June, 1895-Accepted, 6th July, 1895
A Process Ior washing Crude wool.
I, FRITZ RASCHIG, of Ludwigshafen of Rh. Germany, 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:-
As is well known sheep's wool contains besides woolly fibres, a mass of organic
or inorganic substances from which it must be freed by a thorough washing
operation before it can be used for spinning purposes. Washing by means of clean
water does not answer the purpose and hence putrifying urine was first used and
replaced later on by ammonia, but now-a-day, soap and soda is most generally
used. The soapy solutions sbould, in order not to weaken the wool be sufficiently
cold and have a temperature of about 40° C. they should moreover be sufficiently
concentrated; 100 parts containing about 5 parts of soap.
With sodaic soap such 5% solutions cannot be made at a temperature of 40° C.
as a 5% solution of sodaic soap prepared by the aid of heat soon becomes
gelatinized when cooled down to 40° and moreover it is absolutely impossible to
add soda to a 5% solution of sodaic soap, as so soon as a very small quantity of soda
solution is added the sodaic soap separates immediately in flakes; hence potash soap
has been generally used in wool washing although it is much more costly than
sodaic soap.
The best potash soap containing only about 44% of fatty acids and having only
two thirds of the cleaning power of a good sodaic soap containing about 66% of
fatty acids although it costs about as much as the latter.
Although a great economy would be realized by replacing potassic by sodaic
soap considering the extent of the wool washing industry, all efforts in this
direction have hitherto failed, for when trying to use for wool washing purposes,
sodaic soap in a sufficient degree of concentration the soap solution becomes
gelatinized as soon as soda is introduced the wool receives the separating soap
flakes and remains unctuous without the wool fat or sweat being dissolved.
The substitution above mentioned is only possible by adding to the sodaic soap
a substance which increases its solubility in water and imparts thereto the nature of
a potash soap, this substance which is a bye product of the manufacture of
carbolic acid, is cresylic acid. About 1000 parts of water are necessary to
dissolve 20 parts of sodaic soap.
When 5 parts of cresylic acid are added to 20 parts of sodaic soap the mixture
may be dissolved in 100 parts of water at 40° C. and this solution which is
possessed of great washing power will bear moreover the addition of 125 parts of
a 10% solution of soda without separation of soap and is still fairly thin. By
adding lesser quantities of soda, or by diluting with water thoroughly thin and
fluid soap lyes are obtained in a very concentrated state. If the contents in fatty
acids were merely considered with reference to the washing power of this
solution then 20 parts of sodaic soap containing 66% of fatty acids and 5 parts of
cresol would replace 30 parts of potassic soap containing 44% of fatty acids and
as cresylic acid does not cost more than soap a considerable reduction in the cost
of the washing process would be realized; but experience proves that these
expectations are much exceeded, as in reality 20 parts of sodaic soap and 5 parts
of cresylic acid replace 40 parts of potassic soap. The reason therefore is that
cresylic acid possesses cleaning properties similar to those of sodaic soap which are
added thereto.

page_text: It has been found that the washing power of these solutions can be still further
increased by saturating the cresylic acid with caustic soda either entirely or
partially. So long as the necessary quantity of caustic soda is added that will
half saturate the cresylic acid mass in use, the latter has the same favorable
influence upon the solubility of the sodaic soap as if added in a free state; but if
all the cresylic acid is saturated with caustic soda its property of rendering the
soap soluble is diminished notwithstanding the reaction is clearly remarkable.
The proportion of 4 parts of sodaic soap to 1 part of cresylic acid (partly,
entirely, or not at all saturated by caustic soda) such as is indicated in the above
example has been found most useful; but more cresylic acid could be used, the
soap being rendered more readily soluble than above stated although when too
large quantities of cresylic acid are used the smell becomes objectionable in the
washing houses. With less cresylic acid the solubility of the soap is not so
considerably increased and yet it retains considerable advantages as compared with
former processes.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
.A process for washing crude wool by the simultaneous use of sodaic soap and
cresylic acid, the latter being partly, fully, or not at all saturated with caustic
soda.
Dated this 1st day of June 1899.
R. CORE GARDNER,
166 Fleet Street, London,
Agent for the said Fritz Raschig.
R. CORE GARDNER,
166 Fleet Street, London,
Agent for the said Fritz Raschig.