Cellulose Textile Finishing with Low-Temperature Acid Moist Curing
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Solution Overview
Problem
Current cross-linking textile finishes for cellulose fabrics, which aim to provide durable press and crease recovery, often contain formaldehyde, leading to issues like low tear resistance, yellowing, and unpleasant amine smells, and increasing their concentration compromises whiteness and tear strength.
Innovation Solution
A formaldehyde-free cross-linking process for cellulose fabrics using non-formaldehyde cross-linking agents like 1,3-Dimethyl-4,5-dihydroxy-2-imidazolidinone (DMeDHEU) applied under extreme acidic conditions in a moist cure process, involving impregnation, gentle drying, low-temperature curing, and washing, to achieve excellent easy-care properties without yellowing or amine smells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-formaldehyde cross-linking agents are applied under conventional acidic conditions (pH 3-5), then the etherification of cellulose is catalysed, but dialkylhydantoins are formed as side products reducing crosslinker efficiency
Solution Approach 1:
The patent applies extreme acidic conditions (pH 0.8-1.5, significantly lower than conventional pH 3-5) to suppress the formation of dialkylhydantoin side products while maintaining catalysis of the desired etherification reaction. This parameter change in acidity level resolves the contradiction by creating conditions where the main reaction is favoured over side reactions.
2Strength
If the concentration of non-formaldehyde crosslinkers is increased to improve easy-care properties, then crease resistance and dimensional stability are enhanced, but whiteness and tear strength deteriorate
Solution Approach 1:
The patent uses extreme acidic conditions (pH 0.8-1.5) to enable effective crosslinking at lower crosslinker concentrations, thereby achieving good easy-care properties without the yellowing and tear strength reduction associated with high concentrations. The low pH optimizes the reaction efficiency, allowing reduced chemical dosage.
3Reliability
If high curing temperatures (120°C-230°C) are used to achieve complete curing, then crosslinking efficiency is improved, but fabric yellowing and damage increase
Solution Approach 1:
The patent employs low temperature curing (50°C or below, preferably 20-40°C) combined with extreme acidic conditions (pH 0.8-1.5) to achieve effective crosslinking without the yellowing and fabric damage caused by high temperatures. The acidic environment enhances reaction efficiency at lower temperatures.
4Strength
If formaldehyde-containing cross-linking finishes are used to achieve durable press properties, then crease recovery and dimensional stability are improved, but formaldehyde release and unpleasant smells occur
Solution Approach 1:
The patent removes formaldehyde from the cross-linking system by using non-formaldehyde cross-linking agents (glyoxal and substituted ureas). This extraction of the harmful substance eliminates formaldehyde release and unpleasant smells while maintaining the desired durable press properties through alternative crosslinking chemistry.
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 results in cellulose fabrics with high tear strength, excellent whiteness, and no unpleasant amine smell, while maintaining easy-care properties, significantly improving upon existing methods by avoiding the drawbacks of formaldehyde-based treatments.
Implementation Method 1
a catalyst or a mixture of catalysts under acidic conditions... The cross-linking of the cellulose is acid-catalysed
Implementation Method 2
Drying at a temperature of 130°C or below to a residual moisture of from 3 to 30%
Data Source
AI summary
The instant invention relates to a process for the finishing of textiles with a non formaldehyde cross-linking agent based on 2-imidazolidinones wherein by certain process parameters in drying and curing the undesired yellowing and unpleasant amine smell is avoided.