Flame-Resistant Yarn Blends That Prevent the Scaffolding Effect
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Solution Overview
Problem
Current flame retardant fabrics, particularly those using thermoplastic fibers, suffer from the 'scaffolding effect' where the thermoplastic fibers continue to burn when blended with non-melting fibers, leading to incomplete self-extinguishing and potential skin injuries due to molten polymer dripping.
Innovation Solution
Development of yarns combining partially aromatic polyamide fibers, which are melt-spun without flame retardant additives, with flame-resistant fibers like modacrylic or FR cellulose, to create self-extinguishing, non-drip, and durable fabrics that prevent molten polymer from sticking to skin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermoplastic fibers are blended with non-melting flame retardant fibers to improve wear resistance and processability, then the fabric gains superior wear resistance and ease of manufacture, but the thermoplastic fibers continue to burn and drip when exposed to flame, causing incomplete self-extinguishing and skin injuries
Solution Approach 1:
The invention extracts the harmful burning and dripping behavior of thermoplastic fibers by replacing them with melt-spun aromatic polyamide fibers that do not drip when exposed to flame. The solution removes the problematic thermoplastic component while retaining the desired wear resistance through the aromatic polyamide alternative.
Solution Approach 2:
The invention creates a composite fiber system by blending melt-spun aromatic polyamide fibers (which provide wear resistance and self-extinguishing properties) with flame retardant fibers (such as modacrylic or FR-treated cellulose) that provide vapor phase action. This composite approach combines the benefits of both fiber types while eliminating the harmful scaffolding effect.
2Object-affected harmful factors
If aromatic polyamide fibers like Nomex and Kevlar are used to provide inherent flame retardancy, then the fabric achieves excellent flame resistance, but the fibers are difficult and expensive to produce and are not very comfortable
Solution Approach 1:
The invention changes the production parameters of aromatic polyamide fibers by using melt-spinning technology instead of solution spinning. This parameter change makes the production process simpler, more cost-effective, and produces fibers that are more comfortable while maintaining inherent flame retardancy and self-extinguishing properties.
3Object-affected harmful factors
If modacrylic or flame retardant cellulose fibers are used to provide vapor phase action, then the fabric achieves flame resistance through gas emission, but these fibers require post-treatment with phosphorus-based additives to maintain durability through laundering
Solution Approach 1:
The invention enables the fabric to be self-sufficient in flame resistance by using melt-spun aromatic polyamide fibers that inherently self-extinguish without requiring post-treatment with phosphorus-based additives. The aromatic polyamide fibers provide built-in flame retardancy that withstands laundering without additional complex finishing processes.
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 results in fabrics that self-extinguish within 10 seconds in vertical flammability tests, prevent molten polymer dripping, and provide improved wear resistance and comfort while maintaining flame retardancy.
Implementation Method 1
the partially aromatic polyamide fiber excludes flame retardant additives, which are integral to the fiber composition. The yarn including the partially aromatic fiber is referred to in the claims as a 'primary yarn.'
Implementation Method 2
The mechanisms for flame resistance performance of both modacrylic and flame resistant cellulose rely on gases emitted from the fibers which dilute, cool, or chemically neutralize flammable gases (vapor phase action)
Implementation Method 3
gases emitted from the fibers which dilute, cool, or chemically neutralize flammable gases (vapor phase action) and which form intumescent char barriers (condensed phase action)
Data Source
AI summary
Disclosed are technical fibers and yams made with partially aromatic polyamides and a fiber having vapor phase action such as an FR cellulosic fiber. Fabrics made from such fibers and yarns demonstrate superior flame retardancy over traditional flame retardant nylon 6,6 fabrics. Further, the disclosed fibers and yams, when blended with other flame retardant fibers, do not demonstrate the dangerous “scaffolding effect” common with flame retardant nylon 6,6 blended fabrics.