PPS Monofilament Heat Shrinkage Stress Control
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Solution Overview
Problem
Current PPS monofilaments face challenges in achieving consistent physical properties and high precision due to variations in heat shrinkage stress and fineness, which hinder their application in producing high precision filters with low aperture variation rates.
Innovation Solution
A PPS monofilament with controlled continuous heat shrinkage stress variation up to 5% and fineness consistency up to 1.2%, produced through a method involving precise temperature control during extrusion and cooling, and a one-step direct spinning process to minimize stretching tension variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PPS monofilament is produced by separating multifilament into monofilaments, then productivity is improved and cost is reduced, but fineness irregularity occurs in axial direction and consistency of physical properties is lost
Solution Approach 1:
The patent divides the production process into two distinct stages: first producing multifilament with consistent properties, then carefully separating it into monofilaments. This segmentation allows the initial high-precision extrusion to be decoupled from the separation process, maintaining fineness consistency while enabling high productivity through batch production.
Solution Approach 2:
The patent applies preliminary entanglement treatment and stretching before separation to ensure that the monofilaments maintain consistent physical properties after being divided. By pre-establishing the structural integrity and uniformity in the multifilament stage, the subsequent separation process can achieve high productivity without sacrificing fineness irregularity control.
2Stability of the object's composition
If polyalkylene terephthalate is added to PPS to improve dimensional stability, then dimensional stability is improved, but heat resistance and chemical resistance are lost and blend irregularity occurs
Solution Approach 1:
Instead of changing the material composition by adding polyalkylene terephthalate, the patent changes the processing parameters - specifically controlling the extrusion temperature distribution and cooling conditions. This approach achieves dimensional stability through process optimization rather than material blending, preserving the inherent heat and chemical resistance of pure PPS.
Solution Approach 2:
The patent addresses dimensional stability by controlling local temperature distribution in the extrusion process, specifically managing temperature inconsistency between center and periphery of the spinning nozzle. This localized control ensures uniform cooling and solidification, achieving dimensional stability without requiring material additives that would compromise heat and chemical resistance.
3Manufacturing precision
If filter precision is increased by controlling tension during weaving, then aperture variation rate is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent achieves low aperture variation rate by pre-controlling the monofilament properties during extrusion and stretching, rather than requiring complex tension control during the weaving process. By ensuring consistent fineness and minimal heat shrinkage stress variation in the monofilament production stage, the subsequent filter manufacturing becomes simpler while maintaining high precision.
Solution Approach 2:
The patent extracts the precision control requirements from the weaving process and relocates them to the monofilament production process. By achieving fineness consistency and minimal heat shrinkage stress variation during extrusion and stretching, the need for complex tension control devices during weaving is eliminated, reducing manufacturing complexity while maintaining aperture precision.
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 enables the production of high precision filters with enhanced heat resistance, chemical resistance, and extremely low aperture variation rates, ensuring consistent filter performance.
Implementation Method 1
temperature inconsistency between the center and periphery of the spinning nozzle surface is up to 3°C
Implementation Method 2
each filament is cooled by a cooling gas stream at a temperature of at least 5°C and up to 20°C in the area within 100 mm from the spinning nozzle
Implementation Method 3
stretching the filaments between the take up roller and a heated stretching roller
Data Source
Figure 1
AI summary
The present invention takes the forms of: (1) a polyphenylene sulfide monofilament characterized by having a continuous heat-shrinking stress variation of at most 5% and a size uniformity (U%, Normal value) of at most 1.2%; and (2) a drum-shaped fiber package wherein the polyphenylene sulfide monofilament described in (1) has been wound. Provided is a polyphenylene sulfide monofilament having a very small aperture variation rate and being optimal for high-precision filters.