Year: 1896

page_text: I, ARTHUR GEORGE GREEN, F.I.C., F.C.S., of 13 Kings Drive, Heaton Moor
near Stockport in the County of Lancaster Research Chemist, do hereby declare
the nature of my Invention to be as follows:-
In the ordinary method of producing paranitraniline red upon cotton by padding
with an alkaline solution of betanaphthol, drying and passing through a solution
of diazotised paranitraniline, considerable difficulty is experienced, especially upon
cotton yarn, in obtaining even results. Moreover the red dyed in this way has
not the same clearness, brilliancy and blueness of tone as a good Turkey red. I
have discovered that these difficulties may be overcome and a red obtained of far
greater fullness, evenness, brilliancy, and blueness of shade by proceeding in the
following manner:
The yarn previous to being padded with the alkaline naphthol solution is sub-
mitted to a process known as "Mercerisation" which consists in steeping it for
some time in a strong solution of caustic soda. It is then washed and at once
padded with betanaphthol, dried and developed with diazotised paranitraniline in
the usual way. In addition to betanaphthol and caustic soda the alkaline naphthol
solution may contain any suitable additions such as sulphated oil, gelatine, gum,
tragacanth, antimony salts, &c. The diazotised paranitraniline solution may be
prepared from paranitraniline itself or from one of the ready diazotised products
known as "Nitrosamine" "Azophor P.N." and the like. With exception of the
preliminary mercerisation of the cotton the dyeing process is carried out in exactly
the same manner as usual.
The improved process can also be applied to printing, the cotton cloth being first
mercerised then padded with alkaline betanaphthol and finally printed in the
usual way with diazotised paranitraniline solution suitably thickened.
In place of using caustic soda for mercerisation the mercerisation may also be
effected by steeping the cotton in solutions of zinc chloride or sulphuric acid of
suitable concentration.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.

page_text: Improvements in the Production or raramitranmine ne
I, ARTHUR GEORGE GREEN, F.I.C., F.C.S., of 13 Kings Drive, Heaton Moor
near Stockport, in the County of Lancaster, Research 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:-
In the ordinary method of producing paranitraniline red upon cotton by padding
with an alkaline solution of betanaphthol, drying and passing through a solution
of diazotised paranitraniline, considerable difficulty is experienced, especially upon
cotton yarn, in obtaining even results. Moreover the red dyed in this way has
not the same clearness, brilliancy and blueness of tone as a good Turkey red. I
have discovered that these difficulties may be overcome, and a red obtained of far
greater fullness, evenness, brilliancy, and blueness of shade by proceeding in the
following manner:-
The yarn, previous to being padded with the alkaline naphthol solution, is sub-
mitted to a process known as "Mercerisation" which consists in steeping it for
some time in a strong solution of caustic alkali, such as caustic soda. It is then
washed and at once padded with betanaphthol, and developed with diazotised
paranitraniline in the usual way. In addition to betanaphthol and caustic alkali
the alkaline naphthol solution may contain any suitable additions; such as sul-
phated oil, gelatine, gum, tragacanth, antimony salts or the like. The diazotised
paranitraniline solution may be prepared from paranitraniline itself, or from one
of the ready diazotised products known as "Nitrosamine," "Azophor PN," and
the like. With the exception of the preliminary mercerisation of the cotton, the
dyeing process may be carried out in exactly the same manner as usual.
The improved process can also be applied in printing, the cotton cloth, it being
first mercerised, then padded with alkaline betanaphthol, and finally printed in
the usual way with diazotised paranitraniline solution suitably thickened.
Besides other advantages, already mentioned, the new red resists light better
than paranitraniline red obtained in the usual manner.
The cause of the improved results lies in the fact that cotton acquires, by
mercerisation, a greatly increased affinity for alkaline betanaphthol, so that more
naphthol is taken up, even from weaker solutions. This increased affinity of
mercerised cotton for a colourless compound like betanaphthol has, so far as I am
aware, never been previously observed although it has long been known that
mercerised cotton possesses a greater affinity for dyestuffs than does unmercerised
cotton. The formation of the red on the cotton impregnated with betanaphthol
is a secondary chemical process, and not a true dyeing process, so that the deeper
shades obtained do not arise from the increased affinity of the mercerised cotton
for the red colouring-matter, but depend upon the greater quantity of betanaphthol
fixed on the fibre, and probably also upon the physical condition of the latter.
As illustrating the general method of carrying out the process the following
example is given; but I do not limit myself to the details therein set forth.
Cotton is immersed in cold caustic soda solution of 300 Tw. during half an
hour to one hour. If unbleached cotton be used, this should be first freed from oil
by well boiling with soda-ash or 2% caustic soda solution. The cotton after mer-
cerising is washed and grounded with betanaphthol and developed with diazotised
paranitraniline which may be done in the usual well known manner. The
grounding bath can be used at about half the usual strength, viz. 1 lb (instead of
2 lbs) of naphthol to each 8 gallons of water. The time required for mercerisa-
tion can be shortened by using a stronger solution of caustic soda (for instance one
of from 40° to 50° Tw.).

page_text: 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:-
The hereinbefore described improvements in the production of paranitraniline
red upon cotton, consisting in first mercerising the cotton, then treating the mer-
cerised cotton with betanaphthol, and developing with diazotised paranitraniline.
Dated this 1st day of September 1897.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.