Waterless Tanning Composition for Leather

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Solution Overview

Problem

The leather processing industry faces challenges with high water usage leading to significant wastewater generation, chromium pollution, and inefficiencies in chrome and vegetable tanning processes, including the need for external water, salt, and basification, which hinder the adoption of cleaner technologies.

Innovation Solution

A composition comprising 90-95% organic acid, 3-8% primary alcohol, and 2-5% non-ionic surfactant is used for pre-treatment in waterless tanning, utilizing inherent substrate moisture to reduce water and salt usage, and incorporating acid-stable cationic fatliquors to enhance tanning agent uptake and reduce pollution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If water is used during chrome tanning to achieve uniform diffusion and distribution of chromium, then tanning quality is improved, but wastewater discharge with high chromium content increases

Engineering Contradiction:
Improveuniform diffusion and distribution of chromiumVSAvoidchromium pollution in wastewater
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The invention changes the fundamental parameter of the tanning medium from aqueous to non-aqueous (organic solvent-based). This parameter change allows chromium to diffuse and distribute uniformly in the substrate without generating chromium-containing wastewater, as the organic medium does not mix with water and can be separated and reused.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention introduces an organic solvent as an intermediary medium to facilitate chromium transfer to the substrate. This intermediary enables uniform distribution of chromium while preventing direct contamination of water bodies, as the organic medium forms a separate phase that can be easily separated and treated for reuse.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If conventional pickle-based chrome tanning is used, then tanning process is well-established, but water consumption and wastewater generation are high

Engineering Contradiction:
Improvetanning process stabilityVSAvoidwater consumption
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The invention fundamentally changes the tanning process parameter from aqueous-based to non-aqueous organic solvent-based system. This eliminates the need for large quantities of water while maintaining process reliability through controlled chemical reactions in the organic medium, which can be precisely managed and reused.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention replaces the water-based mechanical flushing and rinsing system with an organic solvent system that requires minimal water. The organic medium carries out tanning functions and can be recovered through phase separation, eliminating the need for extensive water-based washing operations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Object-generated harmful factors

If vegetable tanning is used as an eco-friendly alternative, then chromium pollution is reduced, but water consumption remains significant

Engineering Contradiction:
Improvechromium pollutionVSAvoidwater consumption
Core Design Contradiction:
Object-generated harmful factorsVSQuantity of substance

Solution Approach 1:

The invention changes the medium parameter from water-based to organic solvent-based for vegetable tanning. This allows eco-friendly tanning without significant water consumption, as the organic medium can be reused multiple times, combining environmental benefits with resource efficiency.

Inventive Principle:
Principle #35Parameter changes

4Object-generated harmful factors

If waterless chrome tanning technology is adopted, then wastewater discharge is minimized, but adoption cost and process complexity increase

Engineering Contradiction:
Improvewastewater dischargeVSAvoidprocess complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The invention uses organic solvents as intermediaries that facilitate chromium transfer without requiring complex wastewater treatment systems. The organic medium can be separated from the substrate and reused through simple phase separation, reducing both wastewater discharge and treatment complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention implements a recovery system where the organic solvent medium is separated from the tanned substrate and reused for subsequent tanning batches. This recovery approach minimizes wastewater discharge while simplifying the overall process by eliminating the need for complex treatment plants.

Inventive Principle:
Principle #34Discarding and recovering

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

This approach minimizes wastewater discharge, reduces chemical costs, and improves processing efficiency, enabling the production of high-quality, soft, and flexible leather while meeting environmental standards.

Implementation Method 1

2 to 5% (v/v) of a non-ionic surfactant

Methodology Applied
Scientific EffectSurfactant action: Surfactant

Implementation Method 2

The use of water during chrome tanning is very important for attaining uniform diffusion, distribution and hydrolysis of chromium

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 3

the said composition uses the inherent water present in the substrate to be tanned, thereby eliminating the need of addition of external water

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentEP3704275B1A composition useful for pre-treatment in waterless tanning and corresponding tanning process
Publication Date: 2022.12.07 COUNCIL OF SCI & IND RES

AI summary

Use of water during chrome or vegetable tanning is inevitable as it is important for diffusion and distribution of tanning agent in the matrix. This leads to the generation of wastewater containing pollutants such as chromium that needs to be managed effectively. The present invention relates to a novel composition for carrying out the waterless tanning more effectively and easily. The composition preparation involves judicious combination of key specialty chemicals needed for pre-treatment during waterless tanning. The use of new composition for pre-treatment in waterless tanning enables reduction in water requirement, duration of the process as well as cost. Moreover, the use of salt and the basification process are also avoided. The invention makes an effort to attain sustainability in leather industry.