Year: 1898

page_text: A communication from DR. WILHELM ELBERS, of Hagen, Westfalia, in the
Empire of Germany, Managing Director.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, do hereby declare the nature of this invention to be as
follows:-
The basis of all hitherto known processes for fixing indigo on cotton fibres, is
that indigo is first reduced in an alkaline solution to soluble indigo-white by
means of reducing agents and the cotton fibre impregnated with said indigo-
white the indigo being then precipitated in direct contact with the fibre by
oxidising the indigo-white.
a
For the purposes of dyeing indigo is first reduced in the vat, and the goods to
be dyed being then introduced into the vat, and then the indigo-white is exposed
to air for the purpose of oxidising it. For indigo-printing there are several
processes, the basis of all being the same as above. One method consists in print-
ing the cotton-material with a thickened solution of indigo white and then
oxidising (resist method); another method consists in printing the fabric with
a colouring matter containing indigo in a fine state of division, then passing it
through
and then oxidising. The
bath containing reducing agents
process mostly used is, however that of Schlieper. According to this
process the fabric, impregnated with glucose, is printed with indigo dissolved in
a strong alkali then passed quickly through a chamber filled with steam from
which all air has been previously carefully expelled. This short passage through
steam effects the reduction, and the subsequent washing and oxidising by contact
with air effects the regeneration of the indigo and fixes it on the fibre. Unlike
all the above methods, the process according to the present invention enables
indigo to be fixed to cotton fibres on a large scale without previous reduction.
The process consists substantially in mixing finely ground or divided indigo with
preferably comparatively large quantities of vegetable or animal oils or oil deriva-
tives thickening it with suitable substances and then printing it
fimpregnating with it the cotton-fibres, and then subjecting it for about 1 to 2
hours to the action of high-pressure steam (about 7 to 1. atm.). The colour
thus obtained is a good uniform blue-grey colour. In order to fix the colour
completely the action of steam must continue for a long time, but it is not abso-
lutely necessary to use high-pressure steam, only of course the operation takes
correspondingly longer when low-pressure steam is employed. The addition of
a comparatively large quantity of the oils mentioned (olive-oil, sesame-oil, castor-
oil, fat etc.) is essential as without it the grey colour obtained is not so good and
uniform. It appears therefore that the oils partially dissolve indigo during the
steaming operation.
T
htoin crev tones in printing the following may be employed.
on or

page_text: The colouring matter consists of,
100 grammes finely ground indigo, 20%, or refined indigo, or artificial indigo,
of the same strength 200 gr. of olive oil.
700 gr. of tragacanth gum, for thickening.
This colouring matter is printed on bleached cotton-fabric which is then sub-
jected to the action of steam of 0.1 atm. pressure for say, 3 to 4 hours, then the
gum is removed and the fabric treated with soap.
To obtain a grey colour in dyeing the dye to be taken may consist of,
100 gr. finely ground indigo 20%, or refined indigo or artificial indigo of the
same strength.
200 gr. of ricinoleate of soda.
700 gr. tragacanth water. The fabric to be dyed is impregnated with this
dye on
a hot-flue then subjected for 2 hours to the action of steam at 0.7
to 1.0 atm. pressure, then deprived of gum and treated with soap.
The new process has two great advantages over known processes. First it
enables indigo-dye to be combined with other steam-colours, as the steaming for
long periods and at a higher pressure, as required by the process according to the
present invention does not injure most of the steam-colours. Hitherto the only
way of obtaining grey shades with rich steam colours was to use alizarin black
methyl-grey, indian wood etc. But none of the above colours possess sufficient
fastness to light so that the use of grey shades for such fabrics for which a fast
colour is essential, as for instance for furniture coverings, was very limited.
This drawback is obviated by the process according to the present invention,
which enables grey printing tones of extremely great durability and fastness to
light to be obtained.
Another advantage is that the grey colour obtained in printing or dyeing
possesses the same fastness to acids and shows the same re-actions as indigo. It
becomes therefore possible to treat the grey tones obtained by the new process, by
the same etching method (chromic acid process) as used for indigo and thus to
produce the fine effects of indigo-blue kind on grey ground which was hitherto
impossible on a large scale.
Dated 1 1
T
1000
BOULT & WADE,
Agents for the Applicant.
Improvements in or relating to Indigo Printing and Dyeing.
A communication from DR. WILHELM ELBERS, of Hagen, Westfalia, in the
Empire of Germany, Managing Director.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex.
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 ascer-
tained in and by the following statement:-
The basis of all hitherto known processes for fixing indigo on cotton fibre is
that the indigo is reduced in an alkaline solution to a soluble indigo white, by
means of reducing agents: the cotton fibre is then impregnated with the said
indigo-white, and the indigo reproduced on the fibre by oxidising the indigo
white. Thus, for the purpose of dyeing, indigo is first reduced in the vat, and the
goods to be dyed are then introduced into the vat and become impregnated with
the indigo white. They are then exposed to the air for the purpose of oxidising
the indigo-white.

page_text: For indigo printing there are several processes, but all are based on this same
principle. One method consists in printing the cotton material with a thickened
solution of indigo white, and then oxidising (resist method). Another method
consists in printing the fabric with printing colour, containing indigo in a fine
state of division, then passing the goods through a bath containing a reducing
agent and finally oxidising but the process which is perhaps most widely used is
that of Schlieper. According to this well-known process the fabric is impreg-
nated with glucose, and then printed with indigo suspended in a strong alkaline
solution. The goods are then passed quickly through a chamber filled with
steam, as free from air as possible. This short passage through steam effects
the reduction, and the regeneration of the indigo is effected by oxidising, during
the subsequent washing operation, by contact with the air.
The process according to the present invention is based upon an entirely
different principle from all the above methods. The indigo is fixed upon cotton
fibres on a large scale without previous reduction. The process consists sub-
stantially in mixing finely ground or divided indigo with thickening substances,
and preferably with comparatively large quantities of vegetable or animal oils
or oil derivatives. The cotton goods are then impregnated with this printing
colour, and subjected to the action of high pressure steam, (say about seven-
tenths to one atmosphere extra pressure) for a period of about one to two hours.
To fix the colour
The colour thus obtained is a good uniform blue-grey colour.
completely the action of steaming must be continued for a long time, but it is
not necessary to use high-pressure steam, only, of course, the operation takes
longer when low-pressure steam is employed.
The addition of a comparatively large quantity of oily body, (for instance olive
oil, sesame oil, castor oil. fat, etc.) is recommended, because it is essential. if it
be desired, to readily obtain a good and uniform grey colour. It appears likely
that the action of the oils may consist in a dissolving action on the indigo during
the steaming operation.
The following example will serve to illustrate the nature of the invention, and
the manner in which it can be carried into practical effect, but the invention is
not confined to the examples. Parts are by weight:―
EXAMPLE I.
Prepare a printing-colour by mixing 100 parts of finely divided indigo, con-
taining 20% real indigo blue, or refined or synthetic indigo of the same strength,
and 100 parts of starch and tragacanth thickening. Print this mixture on bleached
cotton material, and steam the goods for from three to four hours at one-tenth
atmosphere extra pressure. Free the goods from thickening and wash with soap.
EXAMPLE II.
Prepare a printing-colour by mixing 100 parts of finely divided indigo, con-
taining 20% real indigo blue, or the corresponding quantity of refined or
synthetical indigo, with 200 parts of olive oil and 700 parts of traga-
canth thickening. Print the goods with this mixture and treat them further
exactly as described in Example I.
EXAMPLE III.
In order to obtain a grey colour by printing large surfaces, or,
called, dyeing cotton goods, proceed as follows:-
as it may be
Prepare a printing-colour by mixing 100 parts of finely ground indigo, con-
taining 20% real indigo blue or the corresponding quantity of refined or syn-
thetical indigo, 200 parts of olive oil or turkey red oil, 700 parts of tragacanth
thickening, or, as an alternative, prepare the printing-colour by mixing 100 parts
finely divided indigo, containing 20% real indigo blue, or the corresponding
quantity of refined indigo or synthetical indigo. 50 parts of tallow, and 850 parts
of tragacanth water. Print the goods with either of these printing-colours, and

page_text: dry on the hot flue. Then steam for about two hours at an extra pressure of
from seven-tenths to one atmosphere. Free the goods from thickening and wash
with soap.
"
The process according to the present invention presents in particular two prin-
cipal advantages. It is possible, by the aid of this invention, to combine the
use of indigo with other "" steam colours, that is, colours developed by steam
after printing, for the majority of these steamed colours are not injured by the
action of steam at high-pressure for a long time. Prior to this invention the only
way of obtaining grey shades with the rich steam colours was to use alizarine
black, methyl grey, logwood or similar colours, but none of the above possess
sufficient fastness to light for many purposes. This drawback is obviated by the
process according to the present invention, which enables grey tones of extremely
great durability and fastness to light to be obtained.
Another advantage is that the grey colour obtained possesses the same fastness
to acids and shows the same re-actions as indigo. It is therefore possible to treat
the grey tones obtained by the process of the present invention in the same way
as indigo dyeings are treated. Thus, it may be discharged by the treatment with
chromic acid as practised for discharging indigo, and such effects as have hither-
to been obtained on indigo blue grounds can now be obtained on a grey ground.
Having now particularly described and ascertained the nature of the said inven-
tion as communicated to me by my foreign correspondent and in what manner
the same is to be performed, I declare that what I claim is:-
1. The process of producing grey shades on cotton or similar vegetable fibres
or fabrics by printing or padding the same with printing colour containing
indigo blue and submitting them to a steaming treatment, substantially as
described.
'
2. The process for the production of grey shades on cotton or similar vegetable
fibre or fabric by printing or padding the same with a printing colour containing
indigo blue and an oily or fatty body or derivative thereof, such as are herein-
before described, and then submitting the goods to a steaming treatment,
substantially as hereinbefore described.
Dated this 30th day of September 1898.
BOULT & WADE,
Agents for the Applicant.