Polyamide Dye Aftertreatment for Chlorine Fastness Without Shade Shift

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Solution Overview

Problem

Dyeings on synthetic polyamide fibre materials, especially those using acid dyes, exhibit high sensitivity to chlorine and hypochlorite, leading to color changes and reduced light fastness, with existing treatments either altering the dye shade or being less effective on stronger requirements like those for carpet fabrics.

Innovation Solution

Treatment of dyed polyamide fibre materials with thiourea derivatives, specifically thiourea/formaldehyde/bisphenol condensation products and thiourea/diisocyanate adducts, which improve chlorine fastness and act as stain blocking agents without significantly affecting other fastness properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If natural or synthetic tannic acid derivatives are used to improve chlorine resistance, then chlorine fastness is improved, but the shade of the dyeing is strongly changed and light fastness is reduced

Engineering Contradiction:

Improvechlorine fastnessVSAvoidshade change and light fastness reduction

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the chemical composition parameters by using specific thiourea derivatives (condensation products of thiourea, formaldehyde, and bisphenol or thiourea/diisocyanate adducts) instead of conventional tannic acid derivatives. These compounds have different molecular structures and chemical properties that allow them to protect against chlorine without causing the adverse shade changes and light fastness reduction associated with tannic acid derivatives.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention employs composite chemical structures in the thiourea derivatives, combining multiple functional groups (thiourea, formaldehyde, bisphenol, or diisocyanate components) into a single compound that simultaneously provides chlorine protection while maintaining color integrity and light fastness properties.

Inventive Principle:

Principle #40Composite materials

2Reliability

If conventional chlorine resistance treatments are applied, then chlorine resistance is improved on PA 6.6 knitted fabrics, but performance is essentially reduced in dyed carpet where requirements are distinctly stronger

Engineering Contradiction:

Improvechlorine resistanceVSAvoidperformance on dyed carpet

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The thiourea derivatives exhibit multi-functionality by simultaneously providing effective chlorine resistance on various polyamide substrates (including PA 6.6 knitted fabrics and dyed carpets) while also acting as stain blocking agents. This universal performance across different fabric types and dyeing conditions resolves the limitation of conventional treatments that work on one substrate but fail on others.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention changes the chemical parameters of the treatment composition by using thiourea derivatives with specific molecular weights and functional groups that enable effective penetration and bonding in densely woven carpet fabrics, which are more challenging than knitted fabrics. The compounds' chemical structure allows them to meet the distinctly stronger requirements of dyed carpet applications.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If acid dyes are used for dyeing polyamide fibre materials, then good coloration is achieved, but high sensitivity to chlorine and hypochlorite results in color changes and reduced light fastness

Engineering Contradiction:

Improvecoloration qualityVSAvoidchlorine sensitivity and light fastness

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The thiourea derivatives act as intermediary protective agents between the acid dyeings and the harmful effects of chlorine/hypochlorite. They form a protective layer or complex with the dye-fibre system that prevents direct attack by chlorine, thereby maintaining both the quality of coloration achieved by acid dyes and the reliability against chlorine sensitivity and light fastness issues.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 method enhances chlorine resistance and stain resistance of dyed synthetic polyamide fibre materials, maintaining color integrity and light fastness while effectively preventing staining by conventional food colorants.

Implementation Method 1

treating the fibre material after dyeing with an aqueous liquor comprising a condensation product of thiourea, formaldehyde and a bisphenol or a thiourea/diisocyanate adduct

Methodology Applied

Scientific EffectCondensation reaction:

Implementation Method 2

condensation product of thiourea, formaldehyde and a bisphenol

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Data Source

PatentUS8956423B2Method of increasing chlorine fastness

Publication Date: 2015.02.17 HUNTSMAN INTERNATIONAL LLC

AI summary

The present invention relates to a method of increasing the chlorine fastness of dyed synthetic polyamide fiber materials, which comprises treating the fiber material after dyeing with an aqueous liquor comprising a thiourea/formaldehyde/bisphenol condensate or a thiourea/polyisocyanate adduct.