Improvements in the Process for Producing Fast Colours from Direct Dyes on Cotton.
Year: 1893

page_text: Date of Application, 11th Aug., 1893
Complete Specification Left, 11th May, 1894-Accepted, 16th June, 1894
PROVISIONAL SPECIFICATION.
[Communicated from abroad by The Farbwerke vormals MEISTER LUCIUS
AND BRUNING, of Hoechst a/ Main, in the Empire of Germany, Chemical
Manufacturers.]
Improvements in the Process for Producing Fast Colours from
Direct Dyes on Cotton.
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 :-
It is well known that the azo-colouring matters which dye cotton directly (also
known as congo-diamine and benzidine colouring matters) especially by reason of
their application being very simple, have in a very short time become of great
importance in the cotton-dyeing industry, for which very large quantities are
now used.
There is however a very important objection to the use of these direct dyes for
cotton in many branches of the cotton dyer's business, they are not fast, especially
in washing, and the benzidine colouring matters have the inconvenience that in
washing and fulling they readily bleed on to the undyed parts of the fibre, yarn or
texture.
It is true that the direct dyes for cotton can be fixed very easily on the fibre, by
dyeing it in neutral, feebly alkaline or feebly acid bath; but in washing, the fibre
as readily loses the colour, so that, as stated above, white parts become spotted to
a great extent.
"
My foreign correspondents have succeeded in discovering a process by which this
very great objection can be overcome, at least for a large number of the colouring
matters in question, a process which permits fixing of the colours on cotton fast to
washing and absolutely fast to water. They have discovered that of the colouring
matters of these kinds those which contain lake forming groups can be converted
upon or in the fibre into chrome-lakes which keep to the fibre in an extraordinarily
high degree, so that they resist even strong alkalies and they are not withdrawn
in washing, fulling and soaping, consequently white parts cannot be spotted by
them. This effect is produced by a very simple after treatment by chrome oxide
salts, of cotton previously dyed with the colouring matters in question.
The best suited for this treatment are those simple and mixed azo colouring
matters which dye directly on cotton, and which contain as components

page_text: formed, which adheres to the fibre the more firmly the better the colouring matter
has been fixed to the fibre in the preliminary dyeing.
Any of the chrome oxides will give the desired result, but it will be found more
advantageous to use basic salts, such as for instance, basic chromium-chloride.
The greater or less concentration of the chrome solution is not of great importance,
nor the duration of its action. A nearly complete formation of the chrome-lake
will be obtained for example, by passing the goods for a few minutes through a
boiling solution of a half gramme of solid basic chromium-chloride per litre.
But the effect is obtained with more certainty when somewhat more concentrated
solutions are employed or when the treatment is longer continued.
Instead of treating the goods with boiling chrome oxide salts, the formation of
the lake can be produced by padding, especially when piece goods are in question,
with a concentrated solution and subsequent steaming.
The effect thus obtained is surprising.
The manner of carrying out the invention is described more fully in the following
examples

page_text: a ning temperature for 20 minutes maneno ya
centrifugal machine and dried.
IV.
To produce blue, fast to soap on 50 kilos. of cotton.
A bath is prepared with 2.000 kilos. of the colouring matter obtained from
diazotised benzidine and alpha, alpha, dioxy-naphthaline alpha, sulphonic acid,
5 kilos. of Glauber salts, 0-500 kilos. soap and about 1200 litres water. The cotton
is dyed at boiling temperature for an hour and is then brought to a second bath
containing 1.500 kilos. basic chromium chloride and about 1200 litres water.
It is boiled for 20 minutes, washed, treated in the centrifugal machine and dried.
Dated this 11th day of August 1893.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Process for Producing Fast Colours from
Direct Dyes on Cotton.
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 :-
It is well known that the azo-colouring matters which dye cotton directly (also
known as congo-diamine and benzidine colouring matters) especially by reason of
their application being very simple, have in a very short time become of great
importance in the cotton-dyeing industry for which very large quantities are
now used.
There is however a very important objection to the use of these direct dyes for
cotton in many branches of the cotton dyer's business, they are not fast, especially
in washing, and the benzidine colouring matters have the inconvenience that in
washing and fulling they readily bleed on to the undyed parts of the fibre, yarn
or texture.
It is true that the direct dyes for cotton can be fixed very easily on the fibre,
by dyeing it in a neutral, feebly alkaline or feebly acid bath; but in washing, the
fibre as readily loses the colour, so that, as stated above, white parts become
spotted to a great extent.
My foreign correspondents have succeeded in discovering a process by which
this very great objection can be overcome, at least for a large number of the
colouring matters in question, a process which permits fixing of the colours on
cotton so as to be fast to washing and absolutely fast to water. They have
discovered that, of the colouring matters of these kinds, those which contain lake
forming groups can be converted upon or in the fibre into chrome-lakes which
keep to the fibre with extraordinary firmness, so that they resist even strong
alkalies and they are not withdrawn in washing, fulling and soaping, consequently
white parts can not be spotted by them. This effect is produced by a very simple
after treatment by chrome oxide salts, of cotton previously dyed with the colouring
matters in question.
The best suited for this treatment are those simple and mixed azo colouring
matters which dye directly on cotton, and which contain as components
Salicylic acid,
Othe and mote areentin asid fataluin asid)

page_text: It does not matter what base may have been employed for the production of the
colouring matters in question; any of the direct dyeing colouring matters. that
contain the components named above will do.
The dyeing process is the following.
The cotton is dyed in the usual way, that is to say, according to the nature of
the colouring matter used, in a neutral, feebly alkaline or feebly acid bath,
with the direct dyeing colouring matters;. then the dyed stuffs are treated best in
a fresh bath which contains in solution the chrome oxide salt and which may be
cold, or may be heated, best to boiling temperature. In the second bath the fast
chrome-lake is formed, which adheres to the fibre the more firmly the better the
colouring matter has been fixed to the fibre in the preliminary dyeing.
Any of the chrome oxides will give the desired result, but it will be found more
advantageous to use basic salts, such as for instance, basic chromium-chloride.
The greater or less concentration of the chrome solution is not of great importance,
nor the duration of its action. A nearly complete formation of the chrome-lake
will be obtained, for example, by passing the goods for a few minutes through a
boiling solution of a half gramme of solid basic chromium-chloride per litre. But
the effect is obtained with more certainty when somewhat more concentrated
solutions are employed, or when the treatment is longer continued.
Instead of treating the goods with boiling chrome oxide salts, the formation of
the lake can be produced by padding, especially when piece goods are in question,
with a concentrated solution and subsequent steaming.
The effect thus obtained is surprising.
The manner of carrying out the invention is described more fully in the following
exaninles: