Leather-Like Sheet Composition for Balanced Stretch and Recovery

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Solution Overview

Problem

Existing leather-like sheets fail to maintain a natural dense feeling and soft hand while achieving a small difference in mechanical properties between the machine direction and transverse direction, moderate resistance to elongation, and long-lasting recovery, due to loose entanglement of fibers upon elongation.

Innovation Solution

A leather-like sheet composed of a microfine long-fiber nonwoven fabric with bundles of microfine long fibers and an elastic polymer, where each bundle contains 5 to 70 fibers with an average fineness of 0.5 dtex or less, and a mass ratio of microfine long fibers to elastic polymer ranging from 70/30 to 40/60, with a machine direction/transverse direction ratio of breaking strength between 1/1 to 1.3/1 and elongation at break of 80% or more.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If an entangled nonwoven fabric of short fibers is used to achieve a soft hand and natural dense feeling, then the leather-like sheet shows moderate resistance to elongation, but the entanglement between fibers gradually becomes loose upon elongation and recovery is reduced

Engineering Contradiction:

Improveresistance to elongationVSAvoidrecovery

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the fiber parameter from short fibers to long fibers (average fiber length of 50 mm or more), which fundamentally alters the entanglement behavior. Long fibers maintain stable entanglement structure upon elongation, preventing the gradual loosening that occurs with short fibers, thereby achieving both moderate resistance to elongation and long-lasting recovery

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite structure by impregnating elastic polymer into the long-fiber nonwoven fabric. This composite material combines the structural stability of long fibers with the elastic properties of the polymer, enabling the leather-like sheet to achieve both moderate elongation resistance and excellent recovery characteristics

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If the nonwoven fabric is made from bundles of microfine long fibers with specific fineness to achieve small difference in mechanical properties between MD and TD, then the leather-like sheet shows nearly equal mechanical properties in both directions, but the production complexity increases

Engineering Contradiction:

Improveratio of mechanical properties between MD and TDVSAvoidproduction process complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent specifies precise fiber fineness parameters (average single fiber fineness of 0.5 dtex or less, bundle fineness of 3 dtex or less) and composition ratios (microfine long fibers/elastic polymer from 70/30 to 40/60 by mass) to achieve isotropic mechanical properties. These parameter controls ensure small difference in mechanical properties between MD and TD while maintaining production feasibility

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If microfine long fibers with average single fiber fineness of 0.5 dtex or less are used to achieve a soft hand, then the leather-like sheet exhibits natural dense feeling, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvesoft handVSAvoidfiber fineness control

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent defines specific fineness parameters (single fiber: 0.5 dtex or less, bundle: 3 dtex or less) and mass ratios (microfine long fibers/elastic polymer: 70/30 to 40/60) to achieve the desired soft hand and natural dense feeling. These controlled parameters ensure consistent manufacturing quality while maintaining the tactile properties of natural leather

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 solution results in a leather-like sheet that is soft, resistant to elongation, and exhibits durable recovery, making it suitable for applications such as sport shoes by maintaining nearly equal mechanical properties in both directions.

Implementation Method 1

an elastic polymer impregnated in the microfine long-fiber nonwoven fabric

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS9334609B2Leather-like sheet and process for producing the same

Publication Date: 2016.05.10 KURARAY CO LTD

AI summary

A leather-like sheet containing a microfine long-fiber nonwoven fabric containing an entangled web structure made of bundles of microfine long fibers and an elastic polymer impregnated in the microfine long-fiber nonwoven fabric. The leather-like sheet has a machine direction/transverse direction ratio of breaking strength of 1/1 to 1.3/1, an elongation at break in each of the machine direction and the transverse direction of 80% or more, and a machine direction/transverse direction ratio of elongation at break of 1/1 to 1/1.5. The leather-like sheet has a natural dense feeling, a soft hand, a small difference of mechanical properties in the machine direction and the transverse direction, a moderate resistance to elongation and a durable recovery.