Spandex Fiber Uniformity via Composite Chain Termination
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Solution Overview
Problem
Existing spandex compositions lack high uniformity, particularly in warp-knitting and high content weft-knitting applications, resulting in variations in fiber denier and properties.
Innovation Solution
A spandex fiber or yarn is produced using a polyurethaneurea reaction product of a capped glycol, a blend of diamine chain extenders, and a chain terminator composition including cyclohexylamine, with specific mole ratios and end groups to achieve high uniformity and reduced coefficient of denier variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spandex composition is made with conventional chain terminators, then the production process is simpler, but the fiber uniformity and denier consistency deteriorate
Solution Approach 1:
The patent changes the chemical parameters of the chain terminator from conventional monoalkylurea types to a composition containing both dialkylurea and cycloalkylurea ends. This parameter change in chain terminator composition achieves superior fiber uniformity and denier consistency while maintaining compatibility with existing solution-spinning processes
Solution Approach 2:
The patent uses a composite chain terminator composition containing both dialkylamine (such as diethylamine) and cycloalkylamine (such as cyclohexylamine) components. This composite approach creates polyurethaneurea with both dialkylurea and cycloalkylurea ends, achieving enhanced fiber uniformity through the synergistic effect of different chain terminator types
2Strength
If the mole ratio of diamines is not optimized, then the manufacturing process is simpler, but the elastic properties and strength deteriorate
Solution Approach 1:
The patent optimizes the mole ratio parameter of diamines in the chain extender to a specific range (first diamine to second diamine ratio of about 75:25 to about 85:15). This parameter optimization achieves enhanced elastic properties and strength while maintaining control over the polymerization process
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-spinning process results in spandex with improved fiber uniformity, characterized by lower coefficient of denier variation, enhanced strength, and elastic properties, making it suitable for high-performance knitting applications.
Implementation Method 1
a capped glycol comprising the reaction product of (i) a polyol selected from the group consisting of a polyether polyol, a polyester polyol, a polycarbonate polyol, and combinations thereof; and (ii) a diisocyanate
Implementation Method 2
contacting the capped glycol, the chain extender and the chain terminator composition in a solvent to form a polyurethaneurea in solution
Implementation Method 3
spinning the polyurethaneurea in solution to form the spandex
Data Source
AI summary
Disclosed herein are a highly uniform spandex and process for making such spandex. More particularly, the polyurethaneurea of which such spandex is prepared has both dialkylurea and cycloalkylurea ends, wherein a chain terminator composition includes a dialkylamine such as diethylamine and a cylcoalkylamine such as cyclohexylamine.