Warp Knit Fabric Impregnation for Cross-Direction Stretch

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Solution Overview

Problem

Existing elastic fabrics are costly due to high-priced elastic fibers and require expensive processing, and there is a need for fabrics with desirable stretch properties, especially in the cross-direction, which are not adequately met by current technologies.

Innovation Solution

A method involving the consolidation of warp knit fabrics by drawing them to 30-90% of their initial width and uniformly impregnating them with an elastomeric polymer, followed by solvent removal through wet coagulation, to create fabrics with enhanced cross-direction stretch properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If elastic fibers such as spandex or elastane are used to produce knit fabrics, then the fabrics achieve stretchability, but the cost of production increases significantly

Engineering Contradiction:

ImprovestretchabilityVSAvoidproduction cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the physical state and distribution of elastomeric material from discrete high-cost fibers to a polymer solution impregnated throughout the fabric matrix. By controlling the concentration and distribution of the polymer solution (5-20% by weight), the invention achieves comparable stretchability at lower cost

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces expensive elastic fibers with a more economical elastomeric polymer solution that can be applied and cured in place. The polymer solution serves as a cost-effective alternative to premium elastic yarns while providing the necessary mechanical properties

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Strength

If elastomeric materials are applied to fabric substrates to provide elasticity, then stretch properties are improved, but the cost of processing increases

Engineering Contradiction:

ImproveelasticityVSAvoidprocessing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The fabric substrate is pre-consolidated by drawing to 30-90% of its initial width before polymer impregnation. This preliminary consolidation creates a stable base structure that reduces subsequent processing complexity and cost while ensuring uniform polymer distribution

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces complex mechanical knitting of elastic yarns with a simpler chemical impregnation process. The elastomeric polymer is applied as a solution that penetrates and bonds to the consolidated fabric, eliminating the need for expensive elastic yarn handling and knitting machinery

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Stability of the object's composition

If warp knit fabrics are consolidated to increase stability, then the fabric structure is improved, but the cross-direction stretch is reduced

Engineering Contradiction:

Improvefabric structureVSAvoidcross-direction stretch

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The invention creates a composite structure combining the consolidated warp knit fabric substrate with an elastomeric polymer matrix. The polymer fills the interstices of the consolidated fabric, providing cross-direction stretch while the consolidated substrate maintains structural stability

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The elastomeric polymer is selectively distributed within the consolidated fabric structure, concentrating stretch properties in the cross-direction where needed while maintaining the stability of the machine-direction structure. The polymer impregnation creates localized elastic zones throughout the fabric

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 resulting elastic fabrics exhibit significant cross-direction elongation (>50%) at a lower cost, making them suitable for various applications including apparel and medical uses while maintaining comfort and elasticity.

Implementation Method 1

the consolidated warp knit fabric is substantially uniformly impregnated with a solution comprising an elastomeric polymer dissolved in a solvent

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

solvent is removed from the impregnated consolidated warp knit fabric by wet coagulation to thereby deposit the elastomeric polymer substantially uniformly throughout the thickness of the consolidated warp knit fabric

Methodology Applied

Scientific EffectCoagulation: Coagulation

Data Source

PatentEP2276881B1Elastic knit fabrics with cross direction stretch

Publication Date: 2018.08.29 INVISTA TECHNOLOGIES SARL(CH)

AI summary

Disclosed herein are stretchable elastic fabrics prepared by substantially uniformly impregnating a consolidated warp knit fabric with an elastomeric polymer by treatment with an elastomeric polymer solution. The resulting fabrics exhibit considerable elongation in the cross-direction with little or no machine-direction elongation. Such stretchable elastic fabrics are useful in medical and personal hygiene articles as well as in apparel applications.