Improvements in the Treatment of Silk for Dyeing and Bleaching.
Year: 1897

page_text: Date of Application, 29th Nov., 1897-Accepted, 1st Jan., 1898
COMPLETE SPECIFICATION.
Improvements in the Treatment of Silk for Dyeing and Bleaching.
We, CARL SPINDLER, Manufacturer, and DR. CARL GÖHRING, Chemist, both of
Spindlersfeld, near Berlin, Germany, 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: —
This invention producing a series of new technical effects consists in treating
silk or wild silk (Tussah silk etc.) waste-silk or fibres made therefrom (chape,
bourette, etc.) with bleaching baths, which take away the colouring matters similar
to chlorophyll of the pure silk or the colouring matters of the other silks while
the sericine and fibroine, or the fibroine alone is left intact, these substances
being the constituents which render the fibres fit for technical purposes.
The aqueous solutions of the peroxides of commerce used for bleaching are
mixed in an acid, neutral or alkaline condition with so many parts of an alcohol
or of another suitable body such as aldehyde, acetone and similar bodies, that the
sericine of the fibre is not dissolved; the proportion of 40 parts of alcohol to 60 parts
of peroxide of hydrogen of 3 p.c. strength for instance has been found advan-
tageous in practice, this proportion must of course be adapted to the different
qualities of the goods and the quantity of the alcohol may be substituted by an
equivalent quantity of a similar acting body, such as acetone, aldehyde, and the
like. The liquor with the material to be bleached is then heated in an open
or closed vessel. The duration of the heating and the height of the temperature
depend upon the quality of the goods.
It is entirely immaterial whether the silk is subjected to this process prior
to the reeling off from the cocoon, during the reeling off or after it.
Silk, wild silk, waste silk, fibres made from waste silk in a loose, spun or woven
condition may be treated according to the process above described at any stage of
their preparation or of the dyeing process.
In applying this bleaching process to coloured raw silk a product is obtained
which replaces entirely the silk having a white bast, whereby the value of the
silk with a yellow bast is in particular increased.
In practice moreover a particularly advantageous mode of procedure consists,
so far as colour and quality in subjecting raw or half-boiled off silk to this pro-
cess and then to boil off the gum.
When the silk has previously been half-boiled and is then subjected to this
process a considerably better colour is obtained in all kinds of silk than hitherto
has been possible by the usual methods, without the boiled off silk suffering a
greater loss than was intended.
According to this invention even boiled off silk may be subjected to this
bleaching process and in this case also a better colour and quality is obtained as
the fibroine remains intact and above all is not rendered harsh.

page_text: Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is-
A process of improving any kind of silk, wild silk waste silk and fibres made
therefrom in any stage of their preparation consisting in bleaching in hitherto
usual acid, neutral, or alkaline aqueous bleaching baths but containing as an
essential constituent an alcohol or another suitable chemical body such as aldehyde.
acetone and similar bodies, wherein sericine, as a main constituent of the natural
silk, fibre is insoluble, or wherein fibroine, as the sole basis of the boiled-off fibre,
remains intact, substantially as set forth.
Dated this 20th dow of November 1897
ABEL & IMRAY,
Agents for the Applicants.