Napped artificial leather and production method thereof
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Solution Overview
Problem
Napped artificial leathers often exhibit a nonuniform and coarse appearance with a rough dry touch due to the increased strength of ultrafine fibers, which causes them to become entangled and raised from the base layer when rubbed, leading to an uneven surface.
Innovation Solution
The ultrafine fibers are fixed in a laid-down state by applying a second elastic polymer, adjusting the surface roughness and peak density to prevent excessive raising during friction, resulting in a smoother, more uniform appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strength per one ultrafine fiber is increased, then the fiber durability is improved, but the fibers become difficult to cut during napping treatment and become excessively raised when rubbed, resulting in a coarse appearance
Solution Approach 1:
The patent controls the strength parameter of ultrafine fibers within a specific range (1.5-4.0 cN) to optimize the balance between durability and nappiness. By precisely adjusting fiber strength parameters, the invention prevents excessive raising during rubbing while maintaining fiber durability, thus resolving the contradiction between strength improvement and surface uniformity.
2Strength
If the ultrafine fibers are made stronger, then the material durability is improved, but the fibers gather and become entangled when the napped surface is rubbed, forming a nonuniform appearance
Solution Approach 1:
The patent specifies fiber strength parameters (1.5-4.0 cN) and fiber fineness (0.01-0.5 dtex) to control fiber behavior during rubbing. By optimizing these parameters, the invention ensures fibers maintain individual separation rather than gathering and entangling, thus preserving composition uniformity while maintaining durability.
3Strength
If the ultrafine fibers are relatively thick, then the fiber strength is increased, but the rigidity of each fiber is increased, causing the fibers to be excessively raised from the laid-down state and exposing the base layer
Solution Approach 1:
The patent controls fiber fineness within 0.01-0.5 dtex and strength within 1.5-4.0 cN to optimize the strength-to-rigidity ratio. This parameter optimization ensures fibers remain flexible enough to stay laid-down while maintaining adequate strength, preventing excessive protrusion and base layer exposure.
4Ease of operation
If the napped surface is rubbed, then the fibers move freely and create a dynamic texture, but the surface develops a nonuniform and coarse appearance with a rough dry touch
Solution Approach 1:
The patent optimizes fiber strength (1.5-4.0 cN) and fineness (0.01-0.5 dtex) to achieve balanced fiber mobility. These parameter settings allow fibers to move freely during rubbing for dynamic texture while preventing excessive gathering and entangling that would cause coarse appearance, thus resolving the contradiction between ease of operation and surface shape.
Data Source
AI summary
Disclosed is a napped artificial leather including: a fabric that has been impregnated with a first elastic polymer and that has a napped surface including napped ultrafine fibers with an average fineness of 0.01 to 0.5 dtex, wherein the napped surface has, as measured by a surface roughness measurement in accordance with ISO 25178, an arithmetic mean height (Sa) of 30 μm or less in both a grain direction and a reverse grain direction, and a density of peaks (Spd) having a height of 100 μm or more from a mean height, of 30/432 mm2 or less in both of the grain direction and the reverse grain direction, and a difference (absolute value) in the density of peaks (Spd) between the grain direction and the reverse grain direction is 20/432 mm2 or less.