Cotton Flame-Retardant Composition With Soft Hand Durability
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Solution Overview
Problem
Existing flame retardant compositions for cotton fibers, based on tetrakishydroxyalkylphosphonium (THP) salts and nitrogen compounds, fail to provide durable flame retardancy and a soft hand, especially after multiple washes at high temperatures, and often require additional softeners that can compromise durability.
Innovation Solution
A composition is developed by adding caprolactam to a mixture of water and THP salt, maintaining it at 100°C until no free caprolactam remains, then adding urea and heating to 105°C for at least 10 minutes, creating a condensation product that enhances both flame retardancy and softness, with optional additional softeners like amides and imidazolines to control durability and softness ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If THP salt condensate compositions are used for flame retardant finishing, then flame retardant properties are achieved, but the hand feel becomes harsh and durability to laundering deteriorates
Solution Approach 1:
The invention combines multiple condensation products in a single composition: THP salt-urea condensation product, THP salt-caprolactam condensation product, and THP salt-urea-caprolactam condensation product. This composite formulation integrates the flame retardant efficacy of THP salt-urea with the softening effect of caprolactam, achieving both durable flame retardancy and pleasant hand feel that neither component alone can provide
Solution Approach 2:
The invention optimizes specific parameter ranges including caprolactam content (0.03-0.9 mol per mol THP ions), urea content (0.35-0.55 mol per mol THP ions), and condensation temperature (100-105°C for at least 10 minutes). These parameter controls ensure the formation of the desired condensation products with balanced flame retardant durability and hand softness properties
2Ease of operation
If additional softeners are added to improve hand feel, then softness increases, but flame retardant durability to laundering deteriorates
Solution Approach 1:
Caprolactam serves as an intermediary substance that provides softening effects without compromising flame retardant durability. Unlike conventional softeners that are washed away, caprolactam forms a stable condensation product with THP salt and urea that remains bound to the fiber, maintaining both soft hand feel and durable flame retardancy through multiple laundering cycles
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 composition achieves durable flame retardant properties and a pleasantly soft hand for cotton fibers, maintaining effectiveness after 50 washes at 95°C, with adjustable ratios of caprolactam to urea allowing targeted control of softness and durability, and optional additives like ethylene glycol for improved softness.
Implementation Method 1
adding caprolactam to a mixture of water and a tetrakishydroxyalkylphosphonium (THP) salt, by adding from 0.03 to 0.9 mol and preferably from 0.05 to 0.2 mol of caprolactam per mol of tetrakishydroxymethylphosphonium cations (THP ions), subsequently maintaining the mixture at about 100°C until essentially no free caprolactam is present any longer, then optionally adding urea and maintaining the mixture at a temperature of about 105°C for at least 10 minutes and preferably for from 10 minutes to 2 hours
Data Source
AI summary
Compositions useful for the flame retardant finishing of cotton articles or other cellulose materials are described. The compositions are obtainable by reacting a tetrakishydroxyalkylphosphonium (THP) salt with caprolactam and urea to form a condensation product and subsequently forming a condensate from excess THP salt and excess urea. The compositions endow cotton articles with flame retardant properties and a pleasantly soft hand coupled with good durability to laundering processes.