Conjugate Fiber Side-by-Side Structure Low-Temperature Processability
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Solution Overview
Problem
Conventional conjugate fibers with low-temperature processability suffer from inadequate uniformity and strength in nonwoven fabrics due to high shrinkage and peeling issues during heat processing, limiting their productivity and application in bulky, uniform textiles.
Innovation Solution
A conjugate fiber with a specific side-by-side cross-section structure, comprising an ethylene-α-olefin copolymer as the first component and crystalline polypropylene as the second component, where the ethylene-α-olefin copolymer accounts for 55-90% of the fiber's outer periphery and crystalline polypropylene for 10-45%, with a curved borderline configuration to prevent peeling and shrinkage, enabling low-temperature heat adhesiveness and card passability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a mixture of polyethylene resin having a low melting point (90-125°C) and polyethylene resin having a high melting point (120-135°C) is used as one component of the conjugate fiber, then stable productivity is achieved, but sufficient low-temperature processability is not obtained and the fiber shrinks during heat processing
Solution Approach 1:
The patent divides the fiber into two distinct components with different functions: Component A (containing low-melting-point polyethylene resin) provides heat adhesiveness at low temperatures, while Component B (containing high-melting-point polyethylene resin) prevents shrinkage. This segmentation allows each component to perform its specific function without interfering with the other, resolving the contradiction between productivity and low-temperature processability.
Solution Approach 2:
The patent applies local quality by assigning different resin compositions to different regions of the conjugate fiber. Component A with low melting point (90-125°C) is positioned to provide adhesiveness where needed, while Component B with high melting point (120-135°C) is positioned to provide dimensional stability. This localized functional differentiation enables both low-temperature processing and shrinkage prevention.
2Temperature
If a latently crimpable conjugate fiber containing ethylene-α-olefin copolymer is used, then low-temperature processability is achieved, but the fiber shrinks easily during heat processing and pealing occurs between components
Solution Approach 1:
The patent creates an asymmetric structure where Component A and Component B have fundamentally different melting points and functions. Component A (low-melting-point polyethylene resin) melts at 90-125°C to provide adhesiveness, while Component B (high-melting-point polyethylene resin) remains solid at these temperatures to prevent shrinkage. This asymmetric functional distribution resolves the contradiction between low-temperature processability and shrinkage resistance.
3Ease of manufacture
If the melting adhesive component and non-melting component are pealed during heat processing, then the fiber structure is compromised, but the nonwoven fabric strength cannot be exhibited
Solution Approach 1:
The patent performs preliminary action by establishing a stable conjugate structure where Component A and Component B are firmly bonded before heat processing. The low-melting-point Component A acts as an adhesive binder that melts during heat processing to bond fibers together, while the high-melting-point Component B maintains structural integrity. This preliminary structural arrangement prevents pealing during heat processing and ensures the nonwoven fabric exhibits its full strength potential.
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 results in a nonwoven fabric with excellent bulkiness, uniformity, and heat processing properties at 100°C or lower, reducing shrinkage to 50% or less, thus enhancing the stability and quality of the nonwoven fabric and formed articles.
Implementation Method 1
a first component containing an ethylene -α-olefin copolymer having a melting point of 70 to 100°C
Implementation Method 2
the conjugate fiber containing an ethylene-α-olefin copolymer as a component shrinks easily during heat processing
Data Source
Figure 1
AI summary
A conjugate fiber is provided, in which a first component that contains at least 75% by weight of an ethylene-a-olef in copolymer having a melting point of 70 to 1000C and a second component that contains a crystalline polypropylene forma side-by-side cross section, wherein, in a fiber cross section perpendicular to a fiber axis, the first component accounts for 55 to 90% of an outer periphery of the fiber, a borderline between the first component and the second component forms a curve bulging toward the first component, and an area ratio between the first component and the second component (first component/second component) is in a range of 70/30 to 30/70. The conjugate fiber demonstrates low-temperature processability and excellent card passability when processed into a nonwoven fabric, and can produce a bulky nonwoven fabric having excellent uniformity.