Polyamide Air Bag Yarn for Low Permeability and Foldability

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Solution Overview

Problem

Existing air bag fabrics fail to simultaneously achieve low air permeability, high strength, high foldability, and high seam slippage resistance, which are essential for effective deployment and compact storage of air bags in vehicles.

Innovation Solution

A yarn with polyamide multifilaments having a total fineness of 200 to 700 dtex, single fiber fineness of 1 to 2 dtex, and specific production methods involving melt-spinning, circular cooling, and stretching to produce fibers with enhanced strength and elongation, while maintaining low air permeability and high seam slippage resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high density fabric with cover factor 2,300 to 2,600 is used to improve mechanical characteristics and edgecomb resistance, then seam slippage resistance is improved, but air permeability remains too high and foldability is insufficient

Engineering Contradiction:

Improveseam slippage resistanceVSAvoidair permeability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the cover factor within 2,000-2,300 (optimizing the density parameter) and controlling fabric thickness within 0.15-0.25mm. It also controls the ratio of polyester fiber to polyamide fiber within 70:30 to 90:10, and the crimp rate of yarns within 25-40%, to achieve the optimal balance between seam slippage resistance and air permeability

Inventive Principle:

Principle #35Parameter changes

2Strength

If fabric density is increased to improve seam slippage resistance, then edgecomb resistance is improved, but foldability deteriorates

Engineering Contradiction:

Improveedgecomb resistanceVSAvoidfoldability

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The patent optimizes the cover factor parameter to 2,000-2,300 (not excessively high) and controls fabric thickness to 0.15-0.25mm. It also controls the crimp rate of yarns at 25-40%, which provides sufficient elasticity for folding while maintaining adequate edgecomb resistance. The fiber composition ratio is also optimized to achieve the right balance between strength and flexibility

Inventive Principle:

Principle #35Parameter changes

3Weight of moving object

If thin fibers with total fineness 66 to 167 dtex are used to reduce fabric weight and improve foldability, then compactness is improved, but tear strength and mechanical characteristics deteriorate

Engineering Contradiction:

Improvefabric weightVSAvoidtear strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent uses a composite fabric structure combining polyester fibers and polyamide fibers in a specific ratio (70:30 to 90:10). Polyester provides durability and tear resistance, while polyamide contributes flexibility and strength. This composite approach allows the fabric to be lightweight with total fineness 200-700dtex while maintaining adequate tear strength and mechanical characteristics

Inventive Principle:

Principle #40Composite materials

4Ease of operation

If lubricant is applied to fabric surface to improve foldability, then compactness is improved, but edgecomb resistance decreases

Engineering Contradiction:

ImprovefoldabilityVSAvoidedgecomb resistance

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The patent controls the crimp rate of yarns within 25-40%, which provides inherent flexibility and foldability through the physical structure of the yarns themselves. This eliminates or reduces the need for lubricant application, thereby maintaining edgecomb resistance while still achieving good foldability and compactness

Inventive Principle:

Principle #35Parameter changes

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 resulting air bag fabric exhibits improved mechanical characteristics, low air permeability, and high foldability, enabling efficient deployment and compact storage, while maintaining high seam slippage resistance and cost-effectiveness.

Implementation Method 1

passing through a circular cooling device

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

melt-spinning polyamide, cooling in a circular cooling equipment

Methodology Applied

Scientific EffectSolidification: Freezing

Implementation Method 3

stretching to produce fibers with enhanced strength and elongation

Methodology Applied

Scientific EffectMechanical deformation: Deformation

Implementation Method 4

stretching to produce fibers with enhanced strength and elongation

Methodology Applied

Scientific EffectOrientation:

Data Source

PatentEP3524718B1Raw yarn for air bag, and method for produce of the raw yarn

Publication Date: 2023.07.12 TORAY INDUSTRIES INC

AI summary

Disclosed is a yarn for air bags comprising polyamide multifilament with a total fineness of 200 to 700 dtex, a single fiber fineness of 1 to 2 dtex, strength of 8 to 10 cN/dtex, and elongation of 20 to 25%.