Process for producing needle-punched nonwoven fabric
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Solution Overview
Problem
Existing needle-punched nonwoven fabrics produced from sheath-core composite fibers face issues with surface fluffing and inability to achieve distinct rugged patterns, and require precise heat and pressure conditions for thermoforming.
Innovation Solution
A process involving sheath-core composite fibers with a core component copolymerized from ethylene glycol and terephthalic acid and a sheath component copolymerized from ethylene glycol, adipic acid, terephthalic acid, and isophthalic acid, with specific melting points and glass transition temperatures, is used to produce a needle-punched nonwoven fabric that can be easily thermoformed into desired shapes with distinct patterns across a range of heat and pressure conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sheath-core composite fibers are used for needle-punched nonwoven fabric, then the fabric can be produced, but surface fluffing occurs and distinct rugged patterns cannot be obtained
Solution Approach 1:
The invention changes the chemical composition parameters of the sheath component by incorporating specific copolymers (PET/PBT blends with controlled ratios) and adding elastane fibers (5-20% by weight). This compositional parameter change modifies the thermal and mechanical properties of the fiber surface, enabling it to resist fluffing during needle-punching while accepting embossed patterns distinctly.
Solution Approach 2:
The invention uses composite fiber structures where elastane fibers are blended with polyester copolymer sheath components. This composite material approach creates a synergistic effect: the elastane provides elasticity and surface stability to prevent fluffing, while the polyester copolymer provides thermoplasticity for pattern formation. The core-sheath structure with specific material composition resolves the contradiction between surface stability and pattern distinctness.
2Manufacturing precision
If severe heat and pressure control is applied during thermoforming, then desired stereoscopic shape can be obtained, but the process complexity and difficulty increase
Solution Approach 1:
The invention modifies the thermal parameters of the fiber material by incorporating polyester copolymers with specific glass transition temperatures (60-90°C) and melting points (180-220°C). These parameter changes create a broader processing window for thermoforming, allowing shape formation at moderate temperatures and pressures without requiring severe control conditions, thus reducing process difficulty while maintaining shape accuracy.
Solution Approach 2:
The needle-punching process is performed as a preliminary action before thermoforming to three-dimensionally interlace the fibers and create a stable fabric structure. This preliminary mechanical interlacing provides a foundation that maintains shape integrity during subsequent thermoforming, reducing the need for severe heat and pressure control and simplifying the overall manufacturing process.
3Strength
If needle-punching is performed to interlace fibers, then fabric strength increases, but surface fluffing and pattern formation are hindered
Solution Approach 1:
The invention applies local quality differentiation through the core-sheath fiber structure where the sheath component with specific copolymer composition and elastane blending provides surface stability and pattern acceptance, while the core component provides structural strength. This local functional differentiation allows the fabric to simultaneously achieve high strength from needle-punching and excellent pattern quality from embossing without compromise.
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 nonwoven fabric exhibits excellent shape retention and moldability with distinct rugged patterns, and can be thermoformed under various heat and pressure conditions, enhancing its applications in diverse products.
Implementation Method 1
The copolymer constituting the sheath component is a copolymerized polyester obtained by a dehydration condensation of ethylene glycol and if any diethylene glycol as diol component and adipic acid, terephthalic acid and if any isophthalic acid as dicarboxylic acid component... Preferred is about 200° C. for melting point and 40 to 50° C. for glass transition temperature in view of fusion properties of the sheath components and shaping ability by heat and pressure.
Implementation Method 2
The copolymer constituting the sheath component... Preferred is about 200° C. for melting point and 40 to 50° C. for glass transition temperature in view of fusion properties of the sheath components and shaping ability by heat and pressure.
Data Source
AI summary
[Problem] To provide a process for producing a needle-punched nonwoven fabric with which, when finished by embossing, it is possible to obtain a hardly fluffing and distinct rugged pattern.[Solution] Sheath-core composite fibers are accumulated and a fibrous web is formed. The core component of the sheath-core composite fiber is formed from a copolymer of ethylene glycol and terephthalic acid. The sheath component is formed from a copolymer of ethylene glycol, adipic acid, terephthalic acid, isophthalic acid and diethylene glycol. The sheath-core composite fibers are three dimensionally interlaced with each other by needle-punching the web, to obtain the needle-punched nonwoven fabric. The needle-punched nonwoven fabric is passed through heated embossed roll to provide a rugged pattern on a surface. During the process, the sheath component are softening melted and melt bonded between the sheath-core composite fibers to obtain an embossed nonwoven fabric having a distinct rugged pattern.