High-Crystallinity Olefin Polymer for High-Speed Fine-Fiber Spinning
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Solution Overview
Problem
Existing polypropylene homopolymers and ethylene random copolymers face challenges in achieving high-speed spinning without spin-breaks, maintaining good bonding properties, and producing fine fibers with low linear mass density and high crystallinity.
Innovation Solution
A polypropylene polymer composition with a propylene and α-olefin random copolymer, peroxide-cracked to have a rheological polydispersity index of 3 or less, xylene solubles content of 2.7% or less, and crystallinity of 55% or greater, exhibiting a melt flow rate of 20 dg/min or greater, and optionally containing additives like lubricants and antioxidants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If faster spinning velocities are used to obtain finer fibers, then linear mass density is reduced, but spin-breaks occur with present polypropylene homopolymers and ethylene random copolymers
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molecular weight distribution (MWD) with a specific polydispersity index range of 2.0-3.5, and adjusting the stereoblock content to 5-20%. These parameter optimizations enable the polymer to maintain both fine fiber production at high spinning velocities and resistance to spin-breaks, resolving the contradiction between fiber fineness and spinning reliability.
2Ease of manufacture
If molecular weight distribution is cracked to narrow range and high molecular weight materials are limited, then spinnability is improved, but bonding properties deteriorate when xylene solubles are increased or stereoblock content is increased
Solution Approach 1:
The patent resolves this contradiction through precise parameter control: maintaining polydispersity index between 2.0-3.5 and stereoblock content between 5-20%. This balanced parameter range enables both improved spinnability (through narrowed MWD) and maintained bonding properties (through controlled stereoblock content), avoiding the trade-off present in conventional approaches.
Solution Approach 2:
The patent applies local quality by creating specific microstructural characteristics within the polymer - controlled stereoblock sequences distributed throughout the molecular structure. This local structural organization provides both the spinnability needed for fine fibers and the bonding capability for strong nonwoven fabrics, addressing both requirements simultaneously.
3Manufacturing precision
If fine fibers with lower linear mass density are produced, then fabric softness and coverage are improved, but bonding properties become difficult to maintain
Solution Approach 1:
The patent enables production of fine fibers with linear mass density of 0.5-2.0 denier while maintaining bonding properties through optimized polymer parameters: polydispersity index of 2.0-3.5 and stereoblock content of 5-20%. These parameter controls ensure that even at high spinning velocities required for fine fibers, the material retains sufficient bonding capability.
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 composition enables high-speed spinning without significant spin-breaks, producing fine fibers with improved bonding and coverage properties, leading to softer and stronger nonwoven fabrics.
Implementation Method 1
After peroxide cracking, the random copolymer has a crystallinity of about 55% or greater
Data Source
AI summary
A polymer composition includes a low ethylene random copolymer that can be used to form a meltspun or spunbond article at high spinning velocities. The polymer composition has a low xylene soluble content, a high crystallinity, or both, while having reduced spin-break at high spinning velocities. The polymer composition also exhibits good fiber tenacity and fabric softness.