This document discusses developing a renewable source for tanning leather that is safer and more sustainable than traditional tanning methods. The objectives are to tan leather with hydrothermal resistance above 70°C using renewable polymers as the basis for tanning. The process uses oxidation reactions to generate tanning aldehydes from polysaccharides without producing dangerous aldehydes. Testing shows the tanned leather has good organoleptic and mechanical properties and can be further processed like traditionally tanned leather. The renewable tanning agent is non-toxic, biodegradable, and avoids issues with formaldehyde production compared to traditional organic tanning methods.

1. TANNING WITH RENEWABLE SOURCES
Marco Nogarole
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2. Project objectives
 To develop an innovative product/process for creating «Metal Free»
tanned leathers, in the light of market requests.
 To stabilise the leather (tanning or pre-tanning) with hydrothermal
resistance (Tg) above 70°C and with good mechanical workability
(pressing, splitting and shaving).
 To obtain by-products/waste (shavings, trimmings) that are more
recyclable
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3. RENEWABILITY
Agriculture
and waste
Urban
waste
Animal
waste
Industrial
waste
Forest
waste
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4. • We use natural polymers, polysaccharides as the
basis of our tanning.
• We use oxidation reactions to generate tanning
aldehydes from these complex structures.
• Dangerous aldehydes are not produced.
• The product is purified and analysed to obtain the
same level of reactivity.
POLYALDEHYDES
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5. REACTION USED
To prepare this product we use an oxidation reaction.
We can consider the polysaccharide as a polymer that is full of -OH groups, which can be oxidised
selectively into aldehydes.
All the aldehydes that form are directly connected to the polymer chain.
In this manner aldehydes with a low molecular weight, such as formaldehyde and acetaldehyde, are
not generated.
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6. ALDEHYDES
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7. This product can be made in solid or liquid form, but its main characteristic is
its working pH. Tanning with this polymer ends at pH 8.5.
This characteristic is the reason why we developed a tanning process that
begins directly from the end of maceration and skips the pickle process.
These are the advantages that can be obtained from polyaldehyde tanning:
• Time saving
• Reduced auxiliary chemical use
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8. 50
52
54
56
58
60
62
64
66
68
70
72
74
76
78
80
0 20 40 60 80 100
Tg
% oxidation
% oxidation v Tg
62
64
66
68
70
72
74
76
78
80
2 2,5 3 3,5 4 4,5 5
Tg
concentration
concentration v Tg
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9. ORGANOLEPTIC CHARACTERISTICS
• Light leathers tending towards beige
• Workable using normal mechanical operations
• Can be re-tanned as a normal wet-white
• Non-toxic
• Biodegradable
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10. 0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60
%Biodegraded
Weeks
Concia vegetale Concia al cromo Concia con glutaraldeide Concia IKEM
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11. TANNING TESTS AND RESULTS
Tests were carried out in the project partner tanneries to evaluate the
effectiveness of the new tanning agent.
After tanning, the leathers were re-tanned using recipes for automotive,
furnishings and footwear.
The organoleptic and chemical-physical properties obtained demonstrate
that the tanning and re-tanning process can be adapted to the various
sectors where leather is used.
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12. ADVANTAGES OVER TRADITIONAL ORGANIC TANNING
Synthetic origin Natural origin
Not renewable Renewable
Can release
formaldehyde
No formaldehyde
Toxic product Non-toxic product
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13. PRE-INDUSTRIAL DEVELOPMENT
• Initially, we perfected the reaction on a
laboratory scale with a production capacity
of 10-50 g per day of tanning product.
• We then moved to a production phase in the
laboratory with new instruments that
allowed us to increase production to 2-3 kg
per day.
• The last step taken was to construct a pilot
system that allowed us to prepare up to 200
kg of product per batch.
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14. FINAL BALANCE
• A product that gives the leather a hight Tg.
• The leathers become workable.
• The product answers the set renewability
requirements.
• Predictably competitive cost in comparison with
other innovative tanning agents.
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15. THANK YOU FOR YOUR
ATTENTION
11/04/2018
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