FIELD OF THE INVENTION
The present invention relates to a process for making leather using Aloe vera extract. In
particular, the present invention provides a process for tanning and post tanning of
leather essentially using Aloe vera as a chemical transport medium, whereby it ensures
elimination of water during leather making. The process finds enormous application in
tanning and post tanning operations during leather making. Moreover, the invention
provides an efficient way to minimize the effluents generated by the conventional
leather manufacture, thereby providing a sustainable solution for the minimization of
disposal of the wastes generated by using water as a medium.
BACKGROUND OF THE INVENTION AND DESCRIPTION OF PRIOR ART
Water is used as a medium for the diffusion of chemicals and cleaning of hide/skin to
remove unwanted materials. Hide or skin is commonly preserved using salts for
temporary storage and transportation from slaughter house to tannery. Water is used to
rehydrate the salted skin/hide and subsequent discharge of water with high TDS (Total
Dissolved Solids) is high concern to the tannery. Several, alternate technologies like salt
free/salt less preservation method is adopted to reduce the TDS and water consumption
during soaking process.
Similarly, pickling is yet another unit operation which accounts for high TDS discharge in
the effluent. Development of cleaner and eco-benign technologies for leather
processing is the major intention to march towards eco-friendly manufacturing methods.
Several cleaner technologies have been developed for pre-tanning, tanning and post
tanning processes. Eco-benign leather processing methods are gaining more
recognition in the global platform owing to the rise in concerns over environmental
pollution and as a step towards establishing sustainable manufacturing methods. To
minimize and eliminate the use of water several new technologies are developed such
as waterless chrome tanning, use of non-aqueous medium such as solvents like
ethanol, heptane etc., and super critical carbon dioxide are also used as a medium for
leather making (US2523325A).
Technology like waterless chrome tanning completely eliminate the use of water during
tanning process and minimize the unit operations like pickling and basification
(W020151 04 716A 1 ). The important advantage of waterless chrome tanning is reducing
the number of operations and maximizing the utilization of inherent moisture of the
material to convert raw hides/skins into leathers. However, it limits the application to
tanning process alone.
Application of solvent medium during tanning and post tanning replaces the
conventional aqueous medium with non-aqueous medium. Conventionally, water plays
a critical role in diffusion of chemicals into leather substrate but the non-aqueous
medium aids in the better uptake of chemicals by leather through hydrophobic clustering
environment in the case of non-polar solvents (Bhargavi Narayana Reddy Gari et al.,
2018). The major limitation of the technology is choice of chemicals for post tanning
primarily which needs to be compatible for the selected non-aqueous medium.
Supercritical carbon dioxide is an emerging technology to use liquefied carbon dioxide
as a medium for leather manufacture, this technology paves a loop for the circulation of
solvent in the processing vessel which enables the recycle and reuse of solvent (Ersin
On em 2018 and Ersin On em et al., 2015). Elimination or utilization of alternate medium
for leather making not only reduces the water usage but also eliminates the discharge of
water effluent in the natural water bodies. However, technologies like alternate medium
requires skilled labor and modification either in the conventional manufacturing vessel
or chemicals used for leather making which makes it less viable at commercial.
Application of natural products is gaining interest as they are biocompatible, renewable
and sustainable in nature. Aloe vera extract is a natural product, commonly used in the
field of pharmaceutics and cosmetics. It is also reported to use for its lubrication
property in leather process (US 6953483). The plant has fleshy leaves containing a
translucent gel which is composed of more than 95-98% water, predominantly moisture
and the residual constituents confer significant medicinal properties .
In short it may be summarized that enormous amount of water is being used in leather
processing leading to major effluent problem. The present invention addresses the
problems associate with the prior art processes and aims in the reduction of water use
in leather processing. The solution is provided by the way of using aloe vera in leather
process that completely eliminates the use of water during leather making.
OBJECTS OF THE INVENTION
The main objective of the present invention is therefore to provide a process for making
leather using Aloe vera extract, which obviates the limitations as stated above.
Another objective of the present invention is to utilize Aloe vera extract to eliminate the
use of water during leather processing.
Yet another objective of the present invention is to employ eco-benign medium for pretanning,
tanning and post tanning processes to minimize the discharge of effluent.
Still another objective of the present invention is to eliminate pickling operations during
leather making.
SUMMARY OF THE INVENTION
The present invention provides a process for making leather, which comprises treating
semi-processed leather having moisture content in the range of 30 to 65% and
exhibiting pH in the range of 2.0 to 5.0, with 10 to 100% w/w of modified Aloe vera
extract for a period in the range of 10 to 60 min to obtain conditioned leather, followed
by conventional tanning or post tanning unit operation to obtain wet processed leather.
In an embodiment, the present invention provides a process for making leather using
Aloe vera extract, wherein the steps comprising:
(a) treating Aloe vera extract with organic acids and sonicating for 10 to 30 min
at a temperature in the range of 30 to 40 degree C for a period in the range
of 10 to 60 min;
(b) treating semi-processed leather having moisture content in the range of 30 to
65% and exhibiting pH in the range of 2.0 to 5.0 with 10 to 1 00% w/w of Aloe
vera extract obtained in step [a] to obtain conditioned leather, followed by
conventional tanning or post tanning unit operation to obtain wet processed
leather.
In another embodiment, the present invention provides a process wherein the semiprocessed
leather used is selected from de-limed pelt, pickled pelt, wet blue, vegetable
tanned leather, neutralized leather.
In still another embodiment, the present invention provides a process wherein the
temperature is 37 degree C.
In yet another embodiment of the present invention, the semi-processed leather used
may be such as de-limed pelt, pickled pelt, wet blue, vegetable tanned leather and
neutralized leather.
In another embodiment of the present invention, the process produces leathers similar
to conventional tanned leathers in aqueous medium.
In still another embodiment of the present invention, the physical strength
characteristics of the leather obtained by the developed process matches with the
leathers re-tanned with conventional re-tanning chemicals.
In yet another embodiment of the present invention, the tanning and post tanning
processes produce leathers similar to conventional leather.
In still another embodiment of the present invention, aloe vera extract is used for better
diffusion of tanning and post tanning chemicals in leather.
In yet another embodiment, the process of the present invention minimizes pollution
load in the effluent.
In still another embodiment, the process of the present invention ensures increased
productivity with reduction in process duration as well as optimization of the process.
DETAILS OF BIOLOGICAL RESOURCES USED IN THE INVENTION
SI.No. Common Scientific name Parts used Address from where
name procured
1 . Aloe vera Aloe vera Aloe vera extract Ashokkumar Traders J13,
Koyambedu Market,
Chennai600092
DETAILED DESCRIPTION OF THE INVENTION
The inventiveness of the present invention lies in treating semi-processed leather with
Aloe vera extract as the only medium, under conditions, as herein described, to ensure
better diffusion of chemicals, thereby ensuring economy as well as eco-benign feature
of the process. Aloe vera gel is extracted and thermally treated followed by chemical
modifications. This is further applied for pre-tanning or post-tanning of leather
processmg.
Semi-processed leather having moisture content in the range of 30 to 65% and
exhibiting pH in the range of 2.0 to 5.0 is treated with 10 to 1 00% w/w of Aloe vera
extract for a period in the range of 10 to 60 min. Aloe vera extract is treated with organic
acids to adjust the pH to 2.0 to 5.0 and sonicated for a period in the range of 10 to 30
min at 3rC. The resulting Aloe vera treated conditioned leather is subjected to
conventional tanning or post tanning unit operation to obtain wet processed leather.
Thus, it may be noted that most of the prior art documents reported till date, use
enormous amount of water in leather processing which leads to release of major
effluent. The present invention addresses this problem of water wastage and pollution
generation by reducing the use of water by using Aloe vera during leather processing.
Thus, it leads to zero waste discharge

We Claim:
1. A process for making leather us1ng Aloe vera extract, wherein the steps
compnsmg:
[a) treating Aloe vera extract with organic acids and sonicating for 10 to 30
min at a temperature in the range of 30 to 40 degree C for a period in the
range of 10 to 60 min;
[b) treating semi-processed leather having moisture content in the range of 30
to 65% and exhibiting pH in the range of 2.0 to 5.0 with 10 to 100% w/w of
Aloe vera extract obtained in step [a) to obtain conditioned leather,
followed by conventional tanning or post tanning unit operation to obtain
wet processed leather.
2. A process, as claimed in claim 1, wherein the semi-processed leather used is
selected from de-limed pelt, pickled pelt, wet blue, vegetable tanned leather,
neutralized leather.
3. The process as claimed in claim 1, wherein the temperature is 37 degree C.