Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a process ~or dressing
furs using ground duromer foams ~or the drumming operationO
For the manufacture of fur goods, tanned, greased and,
where required dyed furs are sub~ected to a mechanical
treatment, the so-called dru~ming process. According to this
operation, the hair side and the skin side of the fur are
freed from excess grease, salts, acids and other impurities,
including loose hair. At the same time, the gloss of the
hair and the suppleness of the skin are increased.
According to the conventional drumming operations, furs '
are placed together with first moist, then dry leaf-wood
sawdust (preferably sawdust obtained from the beech tree), - -
which should be as free as possible from resin, into large
drums in which they are tumbled at regular movement. To
increase the drumming effect, solvents, preferably chlorinated
hydrocarbons, may also be added. The two dru~ming operations
using moist and dry sawdust require several hours to be
carried out. When dry sawdust is used, the drumming operation
is often carried out at slightly elevated temperature.
Finally, the furs are freed from the sawdust in drums having ~
slit walls, then beaten and combed. A number of further ~ -
treatments, for example cutting, picking and removing fur
tips, may further improve or modify the hair side of the
furs, if desired.
Wood chips or sawdust as hitherto used according to the
above-said drum~ing method (of, for example, Ullmanns
Encyklopadie der technischen Chemie~ 3rd edition, Vol. 1~
page 577) raise more and more problems, since it is getting
difficult to obtain them. In practice, the intended purpose
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requires only beech-tree sawdust which used to be obtained in large amounts
from the production of wooden shoes and planes. Since, however, in modern -
time, production of those goods is heavily decreasing, whilst the demand for
sawdust to be used for the drumming operation is vigorously increasing, the
supply of this material meets the said difficulty. Therefore, the said mate- ~;
rial has to be bought at a correspondingly increasing price which, in 1972,
was, on an average, 40 to 50% higher than in 1971. Another increase in the
costs for the production o beech-tree sawdust is to be expected. Hence, it
has been necessary for economical reasons to find a possibility of replacing
- 10 wood chips or sawdust by a material which meets all the technical requirements
but can be prepared synthetically; that is to say, in a chemical-technical
way, in order to be independent of natural material and to reach a stable
price, which even decreases in the course of time. In addition to a reason-
able price, the following requirements have to be met by the said substitute
material:
A good adsorption for fats, oils, salts and acids, good wettability,
high resistance to chlorinated hydrocarbons, such as methylene chloride and
trichloroethylene, as well as adequate surface hardness and polishing effi-
ciency.
It has now been found that furs can also be drummed using, for this
mechanical aftertreatment of tanned, greased and where required dyed furs,
ground duromer foams instead of wood chips or sawdust either alone or in ad-
mixture with those natural materials.
Accordingly, the invention provides a process for drumming furs,
which comprises subjecting tanned and greased furs to a mechanical drumming
treatment comprising the steps of contacting tamled, greased and, where re-
quired, dyed furs with a drumming agent comprising a duromer foam selected
from the group consisting of phenol~resol foams, polyurethane hardened foams,
urea~formaldehyde oams and melamine~formaldehyde foams, subjecting the mix-
ture of furs and ground duromer foam to a regular tumbling movement for a
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time sufficient to remove at least a portion of the excess grease, salts,
acidsJ loose hair and other impurities from the furs, removing the drumming
agent from the furs and optionally repeating the operation with the same or
other drumming agent to obtain the desired improvement in the fur quality.
As is known in the art, a duromer foam is an expanded foam thermo-
setting plastics material which does not soften when exposed to the action of
heat. This behaviour may be attributed to cross-linking. Examples of duro- ;
mers are phenolic resins, aminoplast resins (ureaJ melamine), mixed resins '~
composed of phenolic and aminoplast resins and polyurethanes.
The drumming agent of the invention is prepared by crushing duromer
foam blocks or sheets which have been prepared according to the usual methods -
from the corresponding reaction components with the use of propellants, the
reaction product thus obtained is then cut, for example by means of belt saws
and ground, for example, by means of cutting mills.
The duromer foams to be used according to the process of the inven-
tion are advantageously in the form of blocks having a unit weight of from 15
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to 500 kg/m3, preferably from 15 to 100 kg/m3, a unit weight of from 20 to ~0
kg having proved to be especially useful. The blocks are cut into strips
having a size of 50 x 50 x 500 mm (this measure is necessary for the cutting
mill available to be fed), and the resulting strips are placed into the cutting
mill and ground to powder. The advantageous particle size for 80% of the mate-
rial is 0.5 mm, the upper limit for coarse particles being 0.7 mm~ The mate-
rial thus crushed may then be used without further treatment for the drumming .
operation. :
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The following experimental part is to illustrate the process of the
invention, the duromer foam being phenol-resol foam.
The preparation of a phenolic resin foam block is generally known
and disclosed in detail both in the pamphlets of the corresponding raw material
manufacturers and in the competent literature (for example, Kunststoff-
, 30 Handbuch, Vol. X ~uroplaste, Carl Hauser Verlag, Munich, 1968, pages 431 et
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seq.). Starting products are, for example, liquid phenol-resols which harden ~
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of an acid, a propellant, such as hexane or petrol ether, having been added
to the starting material. The blocks thus produced were then crushed as ;
disclosed above.
A number of laboratory-scale optimi~iing tests, including the fat
` adsorption, was carried out using cattle and pigs' fat, for which the
phenolic resin foam powder showed an adsorption which was ten times higher
than that of (beech tree) sawdust, calculated on the same weight. The tests
~ were repeated on an industrial scale in a ~ur dressing factory using the
- furs available, such as mink (especially greasy), racoon, musquash, fox, cat
and sheep. In all these cases, only about one third (calculated on the
weight) of ground phenolic resin foam was used in comparison to the amount
of beech tree sawdust hitherto used.
Moreover, the phenolic resin foam powder showed at least the same
good polishing effect as did the wood sawdust. In drumming tests, in which
the fur had been soaked either with water or with trichloroethylene, the ~ -~
phenolic resin foam powder exhibited an excellent adsorption power for these -
liquids. This property was very surprising in the case of water since nor- -
mally phenolic resin foams can only absorb at most 3 % o~ water. This good
water-adsorption may be due to a large number of capillaries or to the
microstructure of the foam powder. In a drumming test on dyed furs, the
powdered phenolic resin foam showed an adsorption of excess dyestuffS which
was superior to that of wood sawdust. Parallelly operated tests demon-
strated that furs which had been dyed and then drummed with phenolic resin
foam powder did no longer stain wood sawdust used in a second drumming op-
~ eration, whilst the phenolic resin foam powder was still stained by remain-
'f ing dyestuff in a second drumming operation, after the first drumming op
eration had been carried out using wood sawdust.
- Phenolic resln foam powder was chosen for the test, since this
product exhibited better properties than other duromer foams and could be
prepared from the cheapest starting components.
Hence, the advantages of the duromer foam powder used for the
; drumming of furs over those of wood sawdust and, at the same ~ime, the
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technical advantage of the process of the invention are the following:
Better adsorption for fats adhering to the furs,
easier removal of excess dyestuff from dyed furs,
independence of wood sawdust, which is more and
more difficult to obtain,
constant quality inherent in a synthetic product,
control of the production according to quality require-
ments,
lower transport costs compared to those of the voluminous
wood sawdust,
since the foam powder can be prepared where used,
the surface hardness and thus the mechanical properties
can be influenced to a large extent by an adequate choice
of the reaction co~ponent~.
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