Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Title of the Invention:
METHOD OF OBTAINI~G NATIJRAL LEATHER WITH HAIR FOR
WARM U~LIMED SHOES
Field of the Invention
The invention relates to the leather production and,
more particularlv, it relates to a method of obtaining leather
with hair, suitable for the manufacture of warm unlined footwear.
Background of the Invention
At present, warm foot wear made from natural leather is
usually manufactured with the incorporation of a lining. This is
e~plained by the fact that all the hitherto known types of natural
leather used for footwear manufacturing require either a warm
interla~r or an additional material for insulating the wearing
person's foot from the unfinished flesh side of the leather. So
far, the leather industry has not been manufacturing natural
leather grades suitable for the manufacture of warm unlined foot-
wear.
There is known a method of obtaining "suede" leather from
cattle hides without retaining the hair used for the footwear
manufacture, including pretreatment operations, liming, dehairing,
deliming, tanning, splitting, shaving, greasing, drying, sawdusting,
or rolling, stretching, buffing or grinding, etc.
The leather grades obtained by this method cannot be
used for the manufacture of warm footwear without providing the
latter with a warm lining, which involves additional costs and
labor consumption.
There is also known a method of obtaining leather with
hair from cattle hides with the hair length up to 2 cm, suitable
~ for theproduction of warm hair-out footwear, including pretreating
a hide while retaining its hair, pickling, tanning, splitting to
a 2.0 to 2.5 mm thickness, greasing with a grease mixture to the
grease content in the leather body from 12 to 14 per cent, drying
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to the moisture content within 18 to 22 percent, rollinq, stretch-
ing, slight ~rlnding of the flesh side to remove the weak or
loose fibres of the leather tissue.
A disadvantage of this known method is that it does not
provide for processlng the finished leather with the hair length
in excess of 2 cm; furthermore, the leather thus obtained cannot
be made into footwear with the hair inside, l.e. hair-in footwear,
on account of the flesh side presentinq unsuitable appearance.
Therefore, footwear is manufactured from leather thus ob-tained with
~0 the hair out, and with the mandatory incorporation of an in-ternal
lining.
Object of the Invention
It is an object of the present invention to provide a
method of treating hides obtained from cattle of the northern
regions, i.e. the cattle having long hair, to produce leather with
the halr retained and with the flesh side finished to the suede
appearance, suitable for the manufacture of warm unlined footwear
with the hair inside.
Summary of the Invention
The essence of the herein disclosed method of obtaining
leather from cattle hides, suitable for themanufacture of warm
unlined footwear, resides in that all the operations of treating
the unfinished leather are conducted while retaining the hair
thereon.
In accordance with the invention, the disclosed method
of obtaining leather with the hair retained includes pretreating
raw leather obtained from cattle hides, splitting it longitudi.nally
to the thickness of the leather tissue of the grain split wi-thin
2.0 to 2.5 mm, flushing the thus obtained grain split with an
a~ueous solution contain.ing a surface-active agent and a ferment,
pickling, tanning, sha~ing, greasing for introducing the grease in-
to the leather body to a grease content within 3 to 5 percent by
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weight, drying, rolling, stretching, grinding, with all the above-
mentioned operations being conducted while retaining the hair on
the unfinished leather.
In accordance with a feature of the present inventlon,
it is expedient to use for flushing the grain split an aqueous
solution containing by weight 0.3 to 0.5 per cent the surface-
active agent and 0.4 to 0.5 per cent pancreatic ferment. The said
solution has been found to render the leather tissue soft, and the
hair fluffy.
In accordance with another feature of the present in-
vention, it is expedient to use for greasing the unfinished leather
a grease mixture containing 30 percent by weight emulsifier, 20
per cent by weight the product of saponification of sulphonated
vegetable oil with an alkali, 40 per cent by weight sulphonated
fat, 10 per cent by weight fish oil. This composition has been
found to render the leather water-repellent and elastic.
The herein disclosed method provides for obtaining the
new type of natural leather of which one side retains the original
hair, while the other side is suede-finished. The new type of
leather is particularly suitable for the manufacture of new kinds
of warm footwear where a warm lining is essentially the hair of
the leather itself.
The use of thus obtained leather enables to reduce the
cost and labor consumption associated with the manufacture of
warm footwear.
The abovesaid and other advantages of the present in-
vention will be made apparent in the detailed description of the
invention, to follow hereinbelow.
Detailed Description oE the Invention
The initial raw material for obtaining natural leather
suitable for the manufacture of warm unlined footwear are hides
of cattle with the hair length of 2 cm and more.
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he raw leather material, i.e. the hides are sorted
into lots according to their weight, surface area leather body or
tissue thickness, hair length, etc., and then are flushed with
water and fleshed. The thus pretreated unfinished leather is
subjected, with the hair retained, to longitudinal splitting with
the object of reducing the thickness of the leather tissue of the
grain split of the initial leather to 2 to 2.5 mm. The reduced
thickness of the unfinished leather is required for ensuring the
uniform distribution throughout the leather tissue of the com-
ponents and chemicals used at the subsequent treatment stages,
` ~or reducing the consumption of these components and for speedingup the subsequent treatment operations. The thickness range
between 2.0 to 2.5 mm is explained by the fact that with the
unfinished leather split to a thickness substantially short of
2.0 mm, the roots of the hair might be undercut, whereas with the
unfinished leather split to a thickness in excess of 2.5 mm, the
process of footwear manufacture is complicated, and the weight of
the footwear itself is increased, which is obviously undesirable.
Following the splitting, the flesh-side layer is directed to be
processed by the known methods as the flesh split, whereas the
grain-split with the hair is flushed with an aqueous solution con-
tainin~ detergents and sof-tening agents commonly used in the
leather manufacture, such as surface-active agents and ferments.
In this way the softness of the leather tissue and the fluffiness
of the hair are attained. The flushed unfinished leather is then
subjected to pickling with a solution of salts and acids, so as
to prepare the fibres of the leather tissue to tanning, and to
promote the fastness of the hair bulbs in the leather tissue. The
pickled raw leather is air-seasoned for 20 to 24 hours to enhance
the links between the introduced agents and the fibres of the
leather tissue, and then it is squeezed to reduce the water
content to 50...55%, whereafter the unfinished leather is tanned.
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The tanning may be conducted with any suitable known
per se tanning agent, e.g. chromium oxide. In this case the
tannin~ is conducted with the chromium oxide solution at 25...28C.
for 12 to 14 hours, whereafter the unfinished leather is air-
seasoned once again for 8 to 10 hours and squeezed to reduce the
moisture content to 50...55%.
Then the semi-finished material is subjected to shaving
to remove the irregularities of its thickness, whereafter it
is neutralized with an aqueous solution of sodium bicarbonate at
30 to 40C. for 30 to 60 minutes. If required, follow~ng the
neutralization, the semi-finished product is dyed to a specified
colour while being submerged in a solution of a dye and a dispersion
agent, whereafter the product is water-flushed for 20 to 30 minutes
at a temperature of 45 to 55C.
The flushed product is then subjected to greasing inclu-
ding treating the product with a grease mixture of a type commonly
used in the leather productlon, e.g. a mixture conthining by
weight 30% emulsifier, 20% the product of saponification of
sulphonated vegetable oil with an alkali, 40% sulphonated fat,
10% fish oil. The emulsifier in most cases is the product of
saponification ofsynthetic fatty acids~ The amount of the grease
mixture introduced into the semi-finishedproduct is preferably
3 to 5% by weight. With the amount of the~introduced grease short
of 3~, the water-repellent properties of the product have been
found inadequate, whereas with the amount in excess of 5%, the
flesh side of the leather becomes greasy when ground or buffed
to attain the suede finish. If the leather had been dyed, following
the greasing, it is treated with a solution of acetic acid to
fasten the dye. In any case, following the greasing, the semi-
finished leather is flushed with water for 15 to 30 minutes,squeezed and directed to drying. The drying is conducted to reduce
the moisture content to 18...20%.
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7a~38
The dried semi-finished product is subjected to rolling
in a drum to soften the leather, and to staking in a staking
machine and stretchin~ on a stretcher frame.
The ~lesh side of the thus o}~tained semi-finished leather
product is ground or buffed twice: the ~irst grinding or buffing
is performed with an a~rasive material with coarse grains, and
the second grinding or buffing is performed with a fine~grain
abrasive material. Following the grinding or buffing, the
product is subjected to dedusting, which yields the finished
leather.
The herein disclosed method, as it has been explained,
- yields the novel type of leather retaining the original hair.
Following all -the abovedescribed treatment, the hair
would not loose its original properties. On the contrary, the
treatment with the detergents and softening agents renders the
hair clean, fluffy and strong, whereas the flesh side of the leather
has uniform velvet-like appearance, providing for the elegant
outlook of the footwear made therefrom.
The disclosed method is suitable for treating cattle
hldes with the hair length as great as 10 cm: the longer the hair,
the warmer is the footwear manufactured from the leather obtained
by the method.
For the present invention to be better understood, given
hereinbelow is an example of the implementation of the method in
the leather production.
Example.
Cattle hides are classified into lots by the similarity
of the preservation method, the weight, the thickness, the
~ surface area, the hair length, the absence of bald and loose hair
spots.
A lot of the raw material (young bull hides, 6 cm hair
length, green-salted) weighing 1,000 kg is loaded into a drum and
flushed for one hour with running water at a temperature of 16
to 22OC. Following the flushing, the raw product is sub~ected
to ~leshlng and edge-trimming, whereafter it is loaded for
soaking into a drum containing 2,000 litres o~ water at 16...22C-.
The soaking is performed to reconditionthe raw material -to its
initial or raw state. Without dehairing the hides, they are fed
into a splitting machine, to be lon~itudinally split to the
thickness of the grain split from 2.0 to 2.5 mm. The flesh split
is then directed to further treatment according to any suitable
known per se method of leather production.
The grain split with the hair retained thereon is loaded
into a drum containing 2,000 litres o a solution containing
10 kg sodium chloride, 3 kg sulphanol, and pancreatic ferment
obtained by extracting 4 kg of pancreas with an ammonium sulphate `
solution for one hour. The split is treated in this solution
in the rotating drum for 1.5 to 2.0 hours, with the solution
temperature from 30C. to 35C. With the trèatment completed,
the splits are unloaded from the drum, stacked and kept iIl air for
- 15 to 20 minutes. Then the air-conditioned product is loaded
into a drum for pickling, wi-th the drum being filled with 2,000
litres of an aqueous solution containing 150 kg sodium chloride,
and the drum with the product therein is rotated for 35 minutes,
whereafter 20 kg sulphuric acid is added into the drum and the
drum is rotated for 9 hours more, the solution tempera-ture being
maintained at 22...26C. With the nine-hour treatment completed,
the product is unloaded from the drum, the pieces are stacked
and air-conditioned for 22 hours, whereaEter they are subjected
to squeezing with the aim of reducing the mois-ture content to 50...
55~. The squeezed product is loaded into a tanning drum containing
2,000 litres of an aqueous solution of chromium oxide. The
chromium oxide is fed-in in three portions, 10 kg eachj with 30-
minute intervals. After 6...8 hours of the treatment/ 30 Xg of
~ 8 - ,
sodium sulphate are added in three 10 kg portions, with 15-
minute intervals. Four hours after the introduc-tion of the
sodium sulphate, 3 kg of soda ash are added in three 1 kg portions,
with 15-minute intervals. The tanning process is conducted with
the solution temperature maintained at 25...28C. Following 12...
14 hours of the treatment, the tanned product is unloaded from the
drum, and individual pieces are ~stacked so that no wrinkles and
creases are left, to be air-conditioned for 9 hours and then
s~ueezed to the moisture content of 50...55%. The squeezed product
is subjected to the shaving of the flesh side to remove all the
irregularities, whereafter the product is loaded into a drum to
be neutralized in 2,000 litres of a solution containing 25 kg
sodium bicarbonate, for 60 minutes. The temperature of the neu-
tralizing solution is maintained at 30...35C. Following the
neutralization, the product is flushed with running water at 40
50OC. for 3 minutes.
If required, the product is then subjec-ted to dyeing
with any known per sesuitable dye, with the subsequent flushing of
the product and fastening of the dye with acetic acidO
Following the flushing, the semi-finished product is
~reased in a drum with a greasing mixture containing 30~ emulsifier,
20~ the product of saponification of sulphonated vegetable oil
with an alkali, 40~ sulphonated fat, 10~ fish oil, the object
being to introduce the grease into the leather tissue in an amount
of 4~ by weight.
The greasing is conducted at a temperature of 50 to 55C
for 60 minutes, whereafter the semi-finished leather pieces are
unloaded from the drum, stacked grain-to-grain, i.e. hair-to-hair
and air-conditioned for 4 hours, whereafter they are squeezed to
reduce the moisture content to 50.~.55~. The squeezed semi-
finished leather is then put into a dr~ing chamber with the air
temperature of 45 to 50C. The semi-finished product is dried
~7~38
therein to the moisture content of 18 to 22%, whereafter it is
air-conditioned for 24 hours, slightly moistened and loaded into
a rolling drum to be treated -therein for 10 hours. The léather
thus obtained is staked in a staking machine and then stretched
and fixed with simultaneous after-drying to a 14...16% moisture
content. The staked and stretched pieces of leather aré then ground
or buffed twice, first, with a coarse-grain abrasive-coated cloth,
then, with a fine-grain one.
The ground or buffed leather pieces are dedusted, and
thus the leather attains its final marketable form: with the
; ~rain side covered with the clean fluffy hair, the flesh side
having a smooth velvet-like appearance over its entire surface.
The herein disc:losed method is suitable for the treatment
of cattle hides with any hair lengthi however the most suitable
hides are those with the hair length in excess of 2 cm, since the
leather obtained will render the footwear made therefrom warmer.
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