Chrome-free Tanning via Sodium Lignosulfonate Mediator
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current chrome-free tanning methods for ecological leather, such as those using TWS and TWLZ agents, face challenges in achieving uniform tanning, high isoelectric point, and softness, with TWS tanning agents detanning at low pH and TWLZ agents having low softness and poor penetration.
Innovation Solution
A chrome-free tanning process involving the use of TWS tanning agents, sodium lignosulfonate, and TWLZ tanning agents, where sodium lignosulfonate is added to inhibit detanning of TWS and improve the distribution of TWLZ, resulting in a synergistic effect that enhances tanning uniformity, isoelectric point, and softness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If TWS tanning agent is used for chrome-free tanning, then the leather can be tanned without chrome, but the TWS agent detanns at low pH causing non-uniform tanning
Solution Approach 1:
Sodium lignosulfonate is introduced as an intermediary substance that mediates between the TWS and TWLZ tanning agents. It prevents TWS detanning at low pH while facilitating TWLZ penetration, achieving uniform tanning without chrome pollution
Solution Approach 2:
The patent uses a composite tanning system combining TWS organic tanning agent, TWLZ chrome-free metal tanning agent, and sodium lignosulfonate. This composite approach leverages the synergistic effects of different tanning mechanisms to achieve both environmental sustainability and tanning uniformity
2Reliability
If TWLZ tanning agent is used to achieve high isoelectric point, then the leather absorbs post-tanning chemicals well, but the leather softness is reduced
Solution Approach 1:
The patent optimizes the concentration ratio of TWS to TWLZ tanning agents, along with pH and temperature parameters during the tanning process. This parameter optimization achieves high isoelectric point while maintaining leather softness through balanced chemical interactions
3Device complexity
If only TWS agent is used for tanning, then the process is simple, but the isoelectric point is low and softness is insufficient
Solution Approach 1:
The tanning process is segmented into two stages: first using TWS agent for initial tanning, then adding TWLZ agent for secondary tanning. This segmentation allows each agent to perform its optimal function, achieving high isoelectric point while keeping the overall process manageable
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 process achieves a leather with high isoelectric point, excellent absorption of post-tanning chemicals, and prominent softness, overcoming the limitations of existing methods by ensuring even penetration and fixation of tanning agents, thus improving the quality and range of application of the leather.
Implementation Method 1
the TWLZ tanning agent is electropositive, and mainly coordinates with carboxyl of collagen
Implementation Method 2
a TWS tanning agent... mainly reacts with amino of collagen
Implementation Method 3
the obtained crust leather has excellent softness... the wet white leather exhibits excellent absorption and binding abilities to anionic post-tanning chemicals
Implementation Method 4
allowing a binding at 35° C. to 42° C. for 1 h to 3 h
Data Source
AI summary
A chrome-free tanning process of an ecological leather is characterized by a TWS+sodium lignosulfonate+TWLZ ternary tanning process system. The sodium lignosulfonate added can not only have a fixation effect on a TWS tanning agent to make the TWS tanning not undergo detanning at a low pH, but also significantly improve the uniformity of distribution of a TWLZ tanning agent in a hide/skin and promote the formation of a stable cross-linked network structure by the TWLZ tanning agent in a collagen fiber, which effectively overcomes the defects of tanning performance of the existing tanning systems to obtain a leather with uniform and sufficient tanning, a high isoelectric point, a strong electropositivity, excellent absorption for post-tanning chemicals, and a prominent softness, and gives a leather a wide use range and a high quality.