Flame Retardant Polyamide 6 Copolymer via Substituted Caprolactam
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Solution Overview
Problem
Current methods for producing flame retardant polyamide 6 fibers face challenges such as high FR loadings impairing spinnability and tensile properties, agglomeration of FR additives, and the inhibition of chemical recyclability, which are not effectively addressed in existing technologies.
Innovation Solution
A method for preparing a polyamide 6 copolymer through copolymerization with substituted caprolactam bearing flame retardant groups, allowing for the production of recyclable flame retardant polyamide 6 fibers with improved flame retardancy and spinnability, using phosphonates, phosphinates, and phosphazenes as flame retardant moieties, and maintaining chemical recyclability back to ε-caprolactam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high flame retardant loadings (>15 wt%) are used to achieve efficient flame retardancy, then flame retardant effect is improved, but spinnability and tensile properties are impaired
Solution Approach 1:
The patent changes the chemical structure of the flame retardant from traditional additives to functionalized comonomers with specific molecular architectures (cyclic structures with pendant flame retardant groups). This structural parameter change allows the flame retardant to be integrated into the polymer chain at low concentrations (0.1-10 mol%), achieving efficient flame retardancy without the need for high loadings that would impair mechanical properties
Solution Approach 2:
The patent creates a composite molecular structure where flame retardant moieties are covalently bonded to the polyamide 6 backbone through functionalized comonomers. This composite approach integrates the flame retardant function within the polymer matrix at the molecular level, avoiding the agglomeration problems of physical blends and maintaining mechanical integrity at low concentrations
2Object-affected harmful factors
If traditional flame retardant additives are used in melt-compounding, then flame retardant effect is achieved, but agglomeration occurs reducing dispersion uniformity
Solution Approach 1:
The patent performs preliminary chemical modification of the caprolactam monomer before polymerization, incorporating flame retardant groups directly into the monomer structure. This preliminary action ensures uniform molecular-level distribution of flame retardant moieties throughout the polymer chain, eliminating the agglomeration that occurs when additives are mixed into pre-formed polymer through melt-compounding
Solution Approach 2:
The patent uses functionalized caprolactam comonomers as intermediaries to bridge the polymer matrix and flame retardant function. These comonomers act as molecular carriers that incorporate flame retardant groups into the growing polymer chain during polymerization, ensuring uniform distribution without the need for separate additive mixing steps that cause agglomeration
3Object-affected harmful factors
If flame retardant additives are incorporated into PA6 matrix, then flame retardant effect is achieved, but chemical recyclability back to ε-caprolactam is inhibited
Solution Approach 1:
The patent applies local quality by placing flame retardant groups as pendant side chains on the polyamide backbone rather than as crosslinking or terminal groups. This localized incorporation allows the main polymer chain to retain its chemical structure and recyclability, while the pendant groups provide the flame retardant function without interfering with the depolymerization process back to ε-caprolactam
Solution Approach 2:
The patent designs the functionalized comonomer structure to allow for recovery of the original monomer through chemical recycling. The flame retardant groups are attached in a way that they can be removed or transformed during the recycling process, enabling recovery of ε-caprolactam that can be re-polymerized, thus maintaining the circular economy approach
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 solution enables the production of polyamide 6 fibers with instantaneous flame extinguishment, enhanced thermal stability, and preserved chemical recyclability, meeting industrial-scale economic conditions and fire safety standards, while maintaining good physical and chemical properties.
Implementation Method 1
A method for preparing a polyamide 6 copolymer through copolymerization with substituted caprolactam bearing flame retardant groups
Implementation Method 2
polyamide 6 fibers with instantaneous flame extinguishment, enhanced thermal stability
Data Source
AI summary
The invention relates to a method for preparation of a polyamide 6 copolymer, characterised in that a copolymerization reaction is carried out between: o at least one caprolactam of formula (I): o at least one caprolactam, named substituted caprolactam, in which at least one of the carbon atoms is covalently linked to at least one A moiety, said A moiety being selected from the group formed of: # moieties comprising at least one group of formula: (A) #moieties comprising at least one group of formula: (B) # moieties comprising at least one group of formula: (C) The invention also relates to a polyamide 6, to polyamide 6 filaments and filaments yarns.