Process for Decolorising Paper and Textile Fabrics which have become Colored by Immersion in a Waterproofing Solution of Cuprammonium.
Year: 1899

page_text: Date of Application, 19th Jan., 1899
Complete Specification Left, 19th Oct., 1899-Accepted, 13th Jan., 1900
PROVISIONAL SPECIFICATION.
A Process for Decolorising Paper and Textile Fabrics which have
become Colored by Immersion in a Waterproofing Solution of
Cuprammonium.
I, JAMES WILLIAMS, of No. 133, Cannon Street, in the City and County of
London, Gentleman, do hereby declare the nature of this invention to be as
follows:
The present invention relates to an improved process of treating paper and
fabrics to render them waterproof and rot-proof; and the object of it is to
eliminate from the material treated the objectionable discolouration invariably
produced by the process as now performed.
It has long been known that when paper and textile fabrics are immersed
in a solution of cuprammonium hydroxide, then carefully dried, they are
rendered more waterproof and rot-proof and have a greenish-blue colour, if the
fabrics were white or nearly so, before treatment. This greenish-blue colour,
is for some commercial purposes objectionable. The effect of the present inven-
tion is to convert the greenish compound of copper into a white one, so restoring
the fabric to its original colour, or nearly so.
To attain this result, the goods are first immersed in a solution of cupram-
monium hydroxide,-passed-through pressure rollers, to squeeze out the excess
of fluid, and then dried by passing over heated cylinders. The greenish colour
so obtained is then discharged by immersing the fabric in a solution containing
precipitated cyanide of zinc dissolved to saturation in a solution of ammonia
containing 30 to 50 pounds of ammonia gas per hundred gallons. The fabric
is passed between pressure rollers on issuing from the bath and dried over
heated cylinders as before. The green hydrated compound of copper and cellu-
lose is thus converted into white cyanide of copper and oxide of zinc formed
in the liquor, and some also deposited in the fibre. Care must be taken to main-
tain the ammoniacal solution of cyanide of zinc at its proper strength.
Dated this 19th day of January 1899.
PHILLIPS & LEIGH,
Agents for the Applicant.
Process for Decolorising Paper and Textile Fabrics which have
become Colored by Immersion in a Waterproofing Solution of
Cuprammonium.
I, JAMES WILLIAMS, of No. 133, Cannon Street, in the City and County of
London, Gentleman, do hereby declare the nature of this invention and in what

page_text: manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
-
The present invention relates to an improved process of treating paper and
fabrics to render them waterproof and rot-proof; and the object of it is to
eliminate from the material treated the objectionable discolouration invariably
produced by the process as now performed.
It has long been known that when paper and textile fabrics are immersed
in a solution of cuprammonium hydroxide, then carefully dried, they are
rendered more waterproof and rot-proof and have a greenish-blue colour, if the
fabrics were white or nearly so, before treatment. This greenish-blue colour
is for some commercial purposes objectionable. The effect of the present inven-
tion is to convert the greenish compound of copper into a white one, so restoring
the fabric to its original colour, or nearly so.
To attain this result, the goods are first immersed in a solution of cupram-
monium hydroxide, passed through pressure rollers, to squeeze out the excess
of fluid, and then dried by passing over heated cylinders. The greenish colour
so obtained is then discharged by immersing the fabric in a solution containing
precipitated cyanide of zinc dissolved to saturation in a solution of ammonia
containing 30 to 70 pounds of ammonia gas per hundred gallons. The fabric
is passed between pressure rollers on issuing from the bath and dried over
heated cylinders as before. The green hydrated compound of copper and cellu-
lose is then converted into white cyanide of copper, and oxide of zinc formed
in the liquor, and some also deposited in the fibre. Care must be taken to main-
tain the ammoniacal solution of cyanide of zinc at its proper strength.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:--
That process for decolourising paper and textile fabrics which have become
coloured by immersion in a waterproofing solution of cuprammonium, which con-
sists in eliminating the said accidental colouring by immersing the fabric in
a bath composed of a solution containing precipitated cyanide of zinc dissolved
to saturation in a solution of ammonia containing 30 to 70 pounds of ammonia
gas per hundred gallons, then removing the fabric from the bath pressing it
and finally drying it by heat, substantially as described.
1000
PHILLIPS & LEIGH,
No. 22, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.