Heat-Bondable Conjugate Fiber for Soft Nonwoven Fabric
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Solution Overview
Problem
Existing methods for producing heat-bondable conjugate fibers often prioritize either bulkiness or softness, failing to maintain crimp configuration stability and elongation, which results in nonwoven fabrics that are either too rigid or lacking in cushioning and fluid absorption.
Innovation Solution
A heat-bondable conjugate fiber composed of a polyester-based resin and a polyolefin-based resin with a melting point difference of 15°C or more, featuring a side-by-side or eccentric sheath-core structure, and optimized drawing and crimping conditions to achieve a three-dimensional crimp with 10 to 20 crests/2.54 cm and a crimp modulus of 85 to 100%, ensuring stability and softness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If a highly rigid resin or fiber with large fineness is used to obtain bulkiness, then the bulkiness is improved, but the softness is reduced and strong physical irritation to the skin occurs
Solution Approach 1:
The patent employs a conjugate fiber structure combining polyester-based resin (first component) and polyolefin-based resin (second component) with different melting points. This composite structure allows the polyester core to provide structural integrity and bulkiness while the polyolefin sheath provides softness and skin comfort, resolving the contradiction between bulkiness and softness through material composition rather than single-material properties
Solution Approach 2:
The conjugate fiber structure assigns different functional properties to different parts of the fiber: the polyester core (first component) provides bulkiness and structural support, while the polyolefin sheath (second component) provides softness and skin comfort. This local differentiation of material properties within the single fiber structure allows simultaneous achievement of bulkiness and softness without physical irritation
2Object-affected harmful factors
If priority is placed on softness to suppress irritation to the skin, then the softness is improved, but the bulkiness and cushioning effect are greatly reduced
Solution Approach 1:
The dual-component conjugate fiber structure enables the polyester core to contribute to bulkiness and cushioning effect while the polyolefin sheath contributes to softness and skin comfort. This composite approach allows simultaneous optimization of both softness and bulkiness, overcoming the trade-off where improving one property deteriorates the other
Solution Approach 2:
By assigning different functional roles to different parts of the fiber structure, the polyester core provides the necessary bulkiness and cushioning while the polyolefin sheath ensures softness and skin compatibility, achieving both softness and bulkiness without compromise
3Volume of stationary object
If conventional heat-bondable conjugate fibers are used to improve bulkiness, then the bulkiness is improved, but the crimp configuration stability is reduced
Solution Approach 1:
The patent optimizes specific parameters including the melting point difference between polyester and polyolefin components (at least 15°C), the proportion of polyolefin in the sheath (30% or more of outer fiber circumference), and heat treatment conditions (temperature and time). These parameter optimizations ensure that the polyolefin melts and bonds at appropriate temperatures while the polyester maintains structural integrity, preserving crimp configuration stability during heat bonding while achieving bulkiness
Solution Approach 2:
The conjugate fiber structure with specifically selected polyester and polyolefin components creates a composite material system where the melting point difference enables differential thermal behavior: polyolefin melts for bonding while polyester maintains crimp structure, simultaneously achieving bulkiness and crimp configuration stability
4Ease of manufacture
If the melting point of polyolefin is made lower to improve heat bondability, then the heat bondability is improved, but the crimp configuration stability during heat treatment is reduced
Solution Approach 1:
The patent establishes an optimal melting point range for polyolefin (at least 15°C lower than polyester but within specific bounds) and optimizes heat treatment parameters (temperature and time) to achieve complete heat bondability while preventing excessive softening that would compromise crimp configuration. This parameter optimization resolves the contradiction between ease of manufacturing through heat bonding and maintenance of structural stability
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 maintains crimp configuration stability and imparts high softness and bulkiness to nonwoven fabrics, enhancing their performance in applications requiring both properties, such as absorbent and medical materials.
Implementation Method 1
a heat-bondable conjugate fiber formable by heat fusion utilizing thermal energy such as hot air and heated roll
Implementation Method 2
the fiber has an elongation of 50 to 120%, a three-dimensional actualized crimp with 10 to 20 crests/2.54 cm and a crimp modulus of 85 to 100%
Data Source
AI summary
An object of the present invention is to provide a heat-bondable conjugate fiber ensuring that the crimp configuration stability can be maintained even in the state of leaving elongation of the fiber and bulkiness and softness are imparted to the nonwoven fabric, and a nonwoven fabric using the same. The present invention provides a heat-bondable conjugate fiber comprising a first component containing a polyester-based resin and a second component containing a polyolefin-based resin having a melting point lower than the melting point of said polyester-based resin, wherein said second component is a heat-bondable conjugate fiber accounting for a specific range of the outer fiber circumference and having a side-by-side or eccentric sheath-core structure and the fiber has a specific elongation, a specific range of a three-dimensional actualized crimp and a specific range of a crimp modulus.