Lignin-Modified Polyphenolic Tanning Agent for Leather
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Solution Overview
Problem
Current tanning agents in the leather manufacturing process, particularly phenolic syntans, face issues with toxicity and emission problems due to their petro-based nature, and there is a need for a more sustainable, bio-based alternative that enhances hydrothermal stability and organoleptic properties of leather.
Innovation Solution
A method for manufacturing a lignin-modified polyphenolic product by reacting hydroxybenzene compounds with sulphuric acid and diluting the mixture, followed by adding lignin and performing a condensation reaction with aldehydes to create a water-soluble hydroxybenzene-lignin-aldehyde polymer, which increases bio-based content and reduces emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If petro-based phenolic syntans are used for tanning, then hydrothermal stability and organoleptic properties of leather are improved, but toxicity and emission problems occur
Solution Approach 1:
The patent changes the chemical composition parameters by substituting petro-based phenol with bio-based lignin in the syntan structure. This parameter change maintains the functional properties (hydrothermal stability) while eliminating the harmful effects (toxicity and emissions) associated with petro-based phenolic compounds.
Solution Approach 2:
The patent creates a composite tanning agent combining lignin (bio-based) with traditional phenolic syntan components. This composite material achieves both the desired performance (hydrothermal stability, organoleptic properties) and reduced harm (lower toxicity, reduced emissions) by integrating renewable resources into the existing tanning formulation.
2Reliability
If phenol is used in syntan manufacturing, then effective tanning action is achieved, but free phenol content and formaldehyde emissions increase
Solution Approach 1:
The patent extracts and removes the harmful phenol monomer from the final syntan product through controlled condensation reactions. By using lignin as the aromatic building block instead of phenol, the formulation eliminates free phenol content and associated formaldehyde emissions while maintaining effective tanning action through the functional groups of lignin.
Solution Approach 2:
The patent converts the potential harm of using aromatic compounds into a benefit by selecting lignin, which provides the necessary aromatic functionality for tanning without the harmful monomer emissions. The condensation reaction process transforms potential harmful monomers into stable polymeric structures with reduced or eliminated emissions.
3Object-generated harmful factors
If bio-based lignin is introduced to replace phenol, then emission properties are improved, but manufacturing process complexity increases
Solution Approach 1:
The patent segments the manufacturing process into distinct modular steps: (1) sulfonation of lignin, (2) condensation with aldehyde, and (3) purification. This segmentation allows for optimized control of each step, making the bio-based process as manageable and efficient as the traditional petro-based process while achieving reduced emissions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The lignin-modified polyphenolic product improves hydrothermal stability and organoleptic properties of leather, such as fullness and softness, while significantly reducing free phenol content and formaldehyde emissions, achieving up to 60% bio-based content substitution.
Implementation Method 1
reacting a hydroxybenzene compound, optionally in a mixture comprising lignin, with sulphuric acid
Implementation Method 2
performing a condensation reaction by adding formaldehyde or glyoxylic acid or glyoxal or a combination of different aldehydes as an aldehyde to obtain a water soluble hydroxybenzene-lignin-aldehyde polymer-based product
Implementation Method 3
synthetic reactive tanning using aldehydes work differently by either creating crosslinking sites through hydrogen bonding and hydrophobic interactions, or through covalent bond formation on the amine groups of the protein
Implementation Method 4
metal ions (mostly used being chromium ions) crosslink collagen structure through electrostatic interactions followed by complex formation
Implementation Method 5
creating crosslinking sites through hydrogen bonding and hydrophobic interactions
Implementation Method 6
creating crosslinking sites through hydrogen bonding and hydrophobic interactions
Data Source
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AI summary
The invention relates to a method for manufacturing a lignin- modified polyphenolic product to be used in the treatment of leather or skin, comprising the steps of: [1] reacting a hydroxybenzene compound, optionally in a mixture comprising lignin,with sulphuric acid and [2] diluting the reaction mixture with water; wherein the method further comprises either: [3a] adding urea to the reaction mixture obtained in step [2], [4a] if the mixture of step [1] does not comprise lignin, adding water insoluble lignin to the mixture obtained in step [3a], and [5a] performing a condensation reaction by adding formaldehyde or glyoxylic acid or glyoxal or a combination of different aldehydes as aldehyde to obtain a water soluble hydroxybenzene-lignin-aldehyde polymer-based product, or [4b] if the mixture of step [1] does not comprise lignin, adding water insoluble lignin to the reaction mixture obtained in step [2], and [5b] performing a condensation reaction by adding glyoxylic acid or glyoxal or a combination of glyoxylic acid and glyoxal as aldehyde to obtain a water soluble hydroxybenzene-lignin-aldehyde polymer-based product.