Continuous Filament Rayon Fabric With Surface-Biased Flame Retardancy

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Solution Overview

Problem

Existing flame retardant fabrics, such as those made from Nomex fiber, are uncomfortable in hot environments and limited in color options, while also failing to provide adequate moisture wicking and flame retardant properties when used in close-fitting garments that require direct skin contact.

Innovation Solution

A textile fabric formed from continuous filament rayon yarns treated with a phosphorus-based flame retardant compound, where the outer filaments have a phosphorus content at least 25% greater than the inner filaments, using a modified dip-squeeze treatment process to achieve improved comfort, moisture wicking, and flame retardant properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Nomex fiber is used for flame retardant fabrics, then flame retardant properties are improved, but comfort and moisture wicking properties deteriorate

Engineering Contradiction:
Improveflame retardant propertiesVSAvoidcomfort and moisture wicking
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention changes the chemical composition parameters by using rayon continuous filament (a cellulosic fiber) instead of Nomex aramid, and applies a phosphorus-based flame retardant treatment to achieve the required flame retardancy. This parameter change allows the fabric to maintain comfort and moisture wicking properties while achieving flame retardant performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite structure by treating rayon continuous filament fabric with a phosphorus-based flame retardant compound. The combination of the hydrophilic rayon fiber and the phosphorus-based chemical treatment produces a material that exhibits both comfort/moisture wicking properties and flame retardant properties.

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If staple fiber rayon yarns are used, then flame retardant treatment is easier to apply, but fabric comfort and smoothness deteriorate

Engineering Contradiction:
Improveflame retardant treatment applicationVSAvoidfabric comfort and smoothness
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

Instead of using staple fiber rayon (the conventional approach) and accepting its rougher texture, the invention inverts the approach by using continuous filament rayon, which provides superior smoothness and comfort. The invention then develops a specialized flame retardant treatment process adapted for continuous filament structures.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The invention changes the yarn structure parameter from staple fiber to continuous filament, which fundamentally alters the fabric's surface properties to be smoother and more comfortable, while also requiring modifications to the flame retardant treatment parameters to achieve adequate penetration and retention.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If continuous filament rayon yarns are used, then fabric smoothness and moisture wicking are improved, but flame retardant treatment effectiveness deteriorates

Engineering Contradiction:
Improvefabric smoothness and moisture wickingVSAvoidflame retardant treatment effectiveness
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention applies local quality by creating a concentration gradient of phosphorus-based flame retardant compound within the yarn structure, with higher concentration at the periphery and lower concentration in the core. This localized distribution optimizes flame retardant effectiveness at the yarn surface while maintaining the hydrophilic properties of the inner fiber structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention employs preliminary action through multiple sequential dip-squeeze treatments followed by curing steps. The fabric undergoes repeated impregnation cycles with the phosphorus-based compound, with each treatment building upon the previous one to ensure adequate flame retardant retention on the continuous filament structure before final curing.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If phosphorus-based flame retardant treatment is applied to continuous filament rayon, then flame retardant properties are improved, but fabric weight increases

Engineering Contradiction:
Improveflame retardant propertiesVSAvoidfabric weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The invention optimizes the concentration parameter of the phosphorus-based flame retardant compound to achieve the minimum effective level required for flame retardancy. By carefully controlling the add-on level and distribution of the chemical treatment, the fabric achieves adequate flame protection with minimal weight gain.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention applies the flame retardant compound preferentially at the yarn periphery where flame exposure occurs, rather than uniformly throughout the entire yarn cross-section. This localized application reduces the total amount of chemical treatment required, thereby minimizing weight increase while maintaining effective flame retardant protection.

Inventive Principle:
Principle #3Local quality

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 treated continuous filament rayon fabric provides enhanced comfort, durability, and effective flame retardancy, with improved moisture wicking and reduced chafing, meeting or exceeding ASTM flame resistance standards, and is suitable for garments and non-apparel applications.

Implementation Method 1

curing the compound on the fabric

Methodology Applied
Scientific EffectCuring: Photopolymerisation

Implementation Method 2

cured phosphorus-based flame retardant compound durably affixed to the filaments

Methodology Applied
Scientific EffectCross-linking: Chemical Bonding

Implementation Method 3

hydrophilic, exhibiting good moisture wicking properties

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP2004902B1Flame retardant textile fabric
Publication Date: 2009.07.22 SSM IND INC
  • EP2004902B1 patent drawingFigure 1~2
  • EP2004902B1 patent drawingFigure 3
  • EP2004902B1 patent drawingFigure 4

AI summary

A high performance flame retardant textile fabric is provided which is suitable for use in producing close-fitting garments, such as undergarments, that come into direct contact with the skin of the wearer and provide a protective function, as well as in non-apparel applications. The fabric is formed of yarns of rayon continuous filaments, the yarns having outer filaments along the periphery of the yarn and inner filaments in the interior of the yarn. A cured phosphorus-based flame retardant compound is durably affixed to the filaments and imparts flame retardant properties to the fabric. The outer filaments of the yarns have a phosphorus content at least 25% greater than the inner filaments of the yarn.