Thermoplastic Modacrylic Resin for Stable Melt Spinning
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Solution Overview
Problem
Modacrylic fibers produced by existing methods face challenges in achieving strength and stability during melt spinning, particularly due to high drainage loads and solvent recovery costs in wet spinning methods, and limited applicability in melt processing.
Innovation Solution
A thermoplastic modacrylic resin is developed with a copolymer structure that includes a polymer formed from acrylonitrile and an ethylenically unsaturated monomer, where a macromonomer with a specific terminal structure is introduced to enhance strength and stability, and a plasticizer with a boiling point above 200°C is used to improve processability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet spinning method is used to produce modacrylic fiber, then fiber production is achieved, but drainage load is high and solvent recovery cost is high
Solution Approach 1:
The invention changes the fundamental processing parameters by developing a modacrylic resin composition with specific molecular weight distribution (Mw/Mn ratio of 2.0 or more) and controlled constituent unit composition. This enables the material to be processed by melt spinning instead of wet spinning, fundamentally altering the production method's energy characteristics and eliminating solvent recovery requirements.
2Loss of energy
If melt spinning method is used to produce modacrylic fiber, then drainage load and solvent recovery cost are reduced, but yarn breakage occurs and spinning stability is poor
Solution Approach 1:
The invention optimizes critical parameters including molecular weight distribution (Mw/Mn ≥ 2.0), acrylonitrile content (35-84.5 mass%), and ethylenically unsaturated monomer content (15-64.5 mass%). These parameter changes ensure the resin has appropriate melt viscosity and molecular characteristics that prevent yarn breakage during melt spinning while maintaining spinning stability.
Solution Approach 2:
The invention creates a composite polymer system combining modacrylic resin with specific copolymer structures containing acrylonitrile and ethylenically unsaturated monomers. This composite material structure provides both the thermoplasticity needed for melt spinning and the mechanical strength required to prevent yarn breakage, resolving the reliability issue.
3Adaptability or versatility
If modacrylic resin is used for melt processing, then processing application possibility is widened, but resin decomposition occurs because decomposition start temperature is lower than softening temperature
Solution Approach 1:
The invention fundamentally changes the thermal parameters of the modacrylic resin by controlling the molecular weight distribution and monomer composition. This raises the decomposition temperature above the softening temperature, creating a safe processing window that enables various melt processing applications without resin decomposition.
Solution Approach 2:
The invention develops a composite resin system where the specific combination of modacrylic components and copolymers creates enhanced thermal stability. The controlled composition ensures that the decomposition temperature exceeds the softening temperature, allowing the material to maintain compositional stability during melt processing operations.
Data Source
AI summary
A thermoplastic modacrylic resin suitable for producing modacrylic fiber excellent in strength and/or melt spinning stability is provided. The thermoplastic modacrylic resin includes a copolymer. The copolymer includes a polymer (A) that includes a modacrylic resin containing constituent unit 1 derived from acrylonitrile (a1) and constituent unit 2 derived from an ethylenically unsaturated monomer (a2) other than the acrylonitrile (a1), and a polymer (B) that contains constituent unit 3 derived from acrylonitrile (b1). The polymer (B) has first and second terminals and is bound to the polymer (A) at the second terminal. The polymer (B) has 30 mol % or more to less than 70 mol % of all constituent unit 3 in a terminal region that contains the first terminal and contains one-half of all constituent units in the polymer (B). The constituent unit 3 content is 3 to 50 mol % relative to all constituent units in the polymer (B).