Improvements in the Manufacture of Flexible Leather-like Substances.
Year: 1899

page_text: Date of Application, 18th Mar., 1899
Complete Specification Left, 13th Dec., 1899-Accepted, 17th Mar., 1900
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Flexible Leather-like
Substances.
I, LEOPOLD SCHWARZHUBER, of Purkersdorf, near Vienna, in the Empire of
Austria, Engineer, do hereby declare the nature of this invention to be as
follows:-
For a long time experiments have been made to manufacture a leather-like
flexible substance from wood-vencers. Generally these experiments have been
executed in such a manner that the veneers were steamed under pressure whereby
they became soft and flexible. This treatment has offered the serious draw-
back that the fibrous structure of the wood was rendered very bad owing to
the destruction of the fatty materials in the wood, so that the latter after being
dried, became brittle and cracked. This process has been improved in treating
the wood with alkali under a certain pressure. In this improvement the danger
of destroying the fatty materials in the wood is still greater and the wood only
remains flexible a certain time for the reason that in the presence of alkali
owing to its hygroscopicity a rapid drying cannot take place. As soon as the
alkali is transformed into carbonic alkali, which does not take a
long time,
this hygroscopic action ceases and the wood becomes brittle and cracks.
Further it has been tried, to manufacture leather-like wood-preparations by
means of fatty substances, but these preparations have proved the inconvenience
that apart from the great cost of manufacture it is impossible to join several
pieces by means of glue or other adhesive materials, nor it is possible, to attach
the so prepared articles to other objects. In manufacturing leather-like flexible
wooden substances it has to be borne in mind, that when rendering soft the
wood by means of alkali a substituent has to be formed for the fatty materials
in the wood because after removal of the alkali and after the drying of the
preparation all the fibres are to be closed in such a manner, that these fibres
remain flexible and soft. Although the material forming a substitute for the
fatty substances of the wood must be of a flexible nature a direct impregnation
of the wood with gutta-percha or caoutchouc would not be sufficient to solve
the problem for the reason that this process would be too expensive. In my
invention I have overcome all these drawbacks and no breaks or cracks are
possible in the wood manufactured according to my idea. I crush materials
containing starch, sugar or the like, for instance raw potatoes, and boil the
same in an alkali lye of about 10-15° Bé. under a pressure of 3-4 Atm.,
for several hours, until I obtain a gelatinous brown glue-like liquid which when
dry forms a compact quite black-looking mass having much similarity to raw
caoutchouc. In this solution I introduce the veneers for about half an hour,
whereafter the same become flexible and very soft; the flexibility and softness
is attained even then when the veneers are not yet impregnated completely.
If now these veneers are boiled within such a solution under a pressure of
4-5 Atm., they become very flexible but they are difficult to dry. The advantage

page_text: of this process is that even after the drying and after the alkali is transformed
into carbonic alkali, the wood always remains flexible and never cracks or
breaks. The veneers treated according to my invention, have lost the so-called
sound of wood and are completely water-tight. This is a feature of great im-
portance for several industries for instance the industry of manufacturing boot- 5
soles. According to the degree of concentration of the solution the flexibility
of the wood will be greater or less and the colour of the wood will be lighter or
darker.
Improvements in the Manufacture of Flexible Leather-like
Substances.
I, LEOPOLD SCHWARZHUBER, of Purkersdorf, near Vienna, in the Empire of
Austria Engineer, 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 :-
For a long time experiments have been made to manufacture a leather-like 2
flexible substance from wood-veneers. Generally these experiments have been
executed in such a manner that the voneers were steamed under pressure whereby
they became soft and flexible. This treatment has offered the serious draw-
back that the fibrous structure of the wood was rendered very bad owing to
the destruction of the fatty materials in the wood, so that the latter after being !
dried, became brittle and cracked. This process has been improved in treating
the wood with alkali under a certain pressure. In this improvement the danger
of destroying the fatty materials in the wood is still greater and the wood only
remains flexible a certain time for the reason that in the presence of alkali
owing to its hygroscopic nature a rapid drying cannot take place. As soon as the
alkali is transformed into carbonic alkali, which does not take a long time,
this hygroscopic action ceases and the wood becomes brittle and cracks.
Further it has been tried, to manufacture leather-like wood-preparations by
means of fatty substances, but these preparations have proved the inconvenience
that apart from the great cost of manufacture it is impossible to join several
pieces by means of glue or other adhesive materials, nor it is possible, to attach
the so prepared articles to other objects. In manufacturing leather-like flexible
wooden substance it has to be borne in mind, that when rendering the wood
soft by means of alkali a substitute has to be formed for the fatty materials
in the wood because after removal of the alkali and after the drying of the
preparation all the fibres are to be closed in such a manner, that these fibres
remain flexible and soft. Although the material forming a substitute for the
fatty substances of the wood must be of a flexible nature, a direct impregnation
of the wood with gutta-percha or caoutchouc would not be sufficient to solve
the problem for the reason that this process would be too expensive. In my
invention I have overcome all these drawbacks, and no breaks or cracks are
possible in the wood manufactured according to my idea.
The process is executed in the following manner;
Into a boiler which contains 5000 litres, so much natron or alkali lye is

page_text: introduced, until the lye in the boiler shows 4-5° Beaumé. Then 10 kilo-
grammes of starch or 20-25 kilogrammes crushed potatoes are introduced and
the liquid is brought to boil under a pressure of 34 atmospheres by inflowing
steam for instance and boiled so long, till the starch-powder or the potatoes are
totally dissolved. The liquid in this case is of a lightbrown gelatinous glue-
like mass, which, when dried, formis a compact, black-looking mass having much
similarity with raw caoutchouc.
The boiling lasts about 1-2 hours, whereupon about 2-3 cubic metres of
wood-vencers are put into the apparatus, the cover of the receptacle is closed
and the contents steamed under pressure of 4-5 atmospheres. Then the further
heating is stopped and the mass left to cool, whereupon the process is finished.
The advantage of this process is that even after the drying and after the
alkali is transformed into carbonic alkali, the wood always remains flexible and
never cracks or breaks. The veneers treated according to my invention, have
lost the sound of wood and are completely water-proof. This is a feature of
great importance for several industries for instance the industry of manufacturing
boot-soles. According to the degree of concentration of the solution the flexibility
of the wood will be greater or less and the colour of the wood will be lighter
or darker.
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:-
1. Process for manufacturing a leather-like flexible substance from wood-
vencers consisting of crushing materials containing starch or the like, boiling
the same in an alkali lye under pressure of about 3-4 atmospheres intro-
ducing into this mass the veneers and eventually boiling the whole under
pressure of about 4-5 atmospheres substantially as described.
2. The process for producing leather-like flexible substances from wood-
veneers, substantially as described.
DJ AL
104L
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