Microfine Long-Fiber Leather-Like Sheet for Isotropic Recovery
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Solution Overview
Problem
Existing leather-like sheets fail to maintain a natural dense feeling and soft hand while having a small difference in mechanical properties between machine direction and transverse direction, moderate resistance to elongation, and long-lasting recovery, due to loose entanglement of fibers upon elongation, leading to shape distortion in shoes.
Innovation Solution
A leather-like sheet composed of a microfine long-fiber nonwoven fabric with an entangled web structure made of 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 web orientation angle of 73° or more, combined with a grain-finished surface for enhanced durability and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an entangled nonwoven fabric of short fibers is used to achieve a soft hand and natural dense feeling, then the leather-like sheet has a soft hand and initial shape stability, but the entanglement between fibers gradually becomes loose upon elongation resulting in poor recovery and shape distortion
Solution Approach 1:
The patent changes the fundamental parameter of fiber type from short fibers to long fibers (10mm or more in length). This parameter change transforms the entanglement mechanism from weak, loose entanglement of short fibers to strong, stable entanglement of long fibers, enabling the material to maintain its shape and recover after elongation while preserving the soft hand feel
Solution Approach 2:
The patent creates a composite structure by combining long fibers with elastic fibers (5-50% by mass). The long fibers provide structural stability and entanglement strength, while the elastic fibers contribute to flexibility and recovery. This composite material approach resolves the contradiction between softness and shape retention
2Strength
If the nonwoven fabric is highly compacted to improve durability and reduce elongation, then the leather-like sheet gains strength, but the difference in mechanical properties between machine direction and transverse direction increases resulting in anisotropic behavior
Solution Approach 1:
The patent changes the fiber length parameter to 10mm or more, which fundamentally alters the entanglement behavior. Long fibers create more uniform three-dimensional entanglement networks that distribute stress evenly in all directions, achieving both high strength and isotropic mechanical properties simultaneously
Solution Approach 2:
The patent applies local quality by ensuring uniform distribution of long fibers and elastic fibers throughout the nonwoven fabric structure. This uniform local composition throughout the material achieves consistent mechanical properties in all directions (isotropy) while maintaining overall high strength
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 provides a leather-like sheet with nearly identical mechanical properties in both directions, moderate resistance to elongation, and excellent recovery, making it suitable for sport shoes and other applications requiring a natural leather-like feel and durability.
Implementation Method 1
a leather-like sheet having a natural dense feeling similar to that of natural leathers and a soft hand, which is further characterized by having a small difference in mechanical properties between the machine direction and the transverse direction (MD and TD), a moderate resistance to elongation and a long-lasting recovery
Data Source
Figure 1~2
AI summary
A leather-like sheet comprising a microfine long-fiber nonwoven fabric comprising 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 the following features: (1) each of the bundles of microfine long fibers comprises 5 to 70 microfine long fibers having an average single fiber fineness of 0.5 dtex or less; (2) the bundles of microfine long fibers have an average fineness of 3 dtex or less; (3) the entangle web structure comprises superposed webs each comprising the bundles of microfine long fibers; (4) a ratio of the microfine long fibers and the elastic polymer is 70/30 to 40/60 by mass; (5) the elastic polymer is substantially continuous; and (6) a machine direction/transverse direction ratio of breaking strength is 1/1 to 1.3/1, an elongation at break in each of the machine direction and the transverse direction is 80% or more, and a machine direction/transverse direction ratio of elongation at break is 1/1 to 1/1.5. With these features, the leather-like sheet has a natural dense feeling resembling natural leathers, 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.