Napped leather-like sheet and method for producing the same
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Solution Overview
Problem
Conventional napped leather-like sheets with fibers fixed using an elastic polymer fail to achieve a tactile impression similar to nubuck, which has a moist and slimy touch, and often result in a coarse tactile impression.
Innovation Solution
A napped leather-like sheet is created with a surface comprising napped regions of ultrafine fibers and thermally welded unnapped regions, where the unnapped regions account for 5 to 30% of the surface area, and the ratio of average nap length to overall average width of unnapped regions is adjusted between 0.5 to 1.5, preventing direct contact with the unnapped regions and reducing dry feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If napped fibers are fixed with an elastic polymer, then the fibers are secured in place, but the surface develops a coarse tactile impression that prevents achieving a moist and slimy touch like nubuck
Solution Approach 1:
The invention extracts the harmful elastic polymer coating from the fiber surface while maintaining fiber fixation through thermal welding of the non-woven fabric structure itself. This removes the source of coarse tactile impression while preserving the necessary fiber securation.
Solution Approach 2:
The invention replaces the mechanical/chemical bonding mechanism (elastic polymer coating) with a thermal welding mechanism that fuses fibers directly at their contact points, eliminating the need for polymer coating and its associated coarse surface texture.
2Object-affected harmful factors
If the napped region accounts for a higher ratio to achieve moist and slimy touch, then the tactile impression improves, but the durability of unnapped regions decreases
Solution Approach 1:
The invention creates distinct local zones with different properties: napped regions provide moist tactile impression while thermally welded unnapped regions provide structural durability. The specific ratio range (5-30% unnapped regions) optimizes the balance between these local qualities.
3Object-affected harmful factors
If ultrafine fibers are used to achieve nubuck-like tactile impression, then the surface softness improves, but the fibers become more susceptible to wear and loss of napped state
Solution Approach 1:
The invention applies thermal welding as a preliminary action to secure the non-woven fabric structure before the napping process. This pre-fixation prevents ultrafine napped fibers from being lost during subsequent handling and use, while maintaining their soft tactile properties.
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 achieves a tactile impression with a moist and slimy touch while maintaining excellent durability and design quality of the unnapped regions, reducing the likelihood of a coarse tactile impression and ensuring color fastness to water.
Implementation Method 1
a plurality of unnapped regions including the ultrafine fibers that have been thermally welded
Data Source
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AI summary
A napped leather-like sheet is used that includes a fiber base material including a non-woven fabric of ultrafine fibers and an elastic polymer, wherein the napped leather-like sheet has a surface including a napped region including the ultrafine fibers that have been napped, and a plurality of unnapped regions including the ultrafine fibers that have been thermally welded and laid down, the unnapped regions being surrounded by the napped region and present discontinuously, a total area of the unnapped regions accounts for 5 to 30% of an area of the surface, and Y/X is 0.7 to 1.5, where X represents an average nap length of the napped ultrafine fibers and Y represents an overall average length of averages of widths, orthogonal to a longitudinal direction, of the unnapped regions.