PHA Multifilament Cooling and Stretching for Breakage
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Solution Overview
Problem
The challenge is to produce a high-strength multifilament with thin individual filaments containing poly(3-hydroxyalkanoate) resin, as previous attempts to stretch undrawn multifilaments with a high stretching ratio resulted in filament breakage and inability to obtain a multifilament with small mean fineness and low coefficient of variation.
Innovation Solution
An undrawn multifilament with 30 or more individual filaments containing poly(3-hydroxyalkanoate) resin and a nucleating agent, having a mean fineness of 30 dtex or less and a coefficient of variation of 33% or less, is produced using a melt spinning method with a spinning nozzle having 30 or more discharge holes and cooled by a gas at 0-50°C, followed by stretching with a stretching roll unit at a ratio of 1.5 or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the stretching ratio is increased to enhance the degree of polymer orientation and strength, then the strength of the multifilament is improved, but the individual filaments break during stretching
Solution Approach 1:
The patent applies parameter changes by precisely controlling the cooling temperature (0-50°C) and cooling rate of the undrawn multifilament before stretching. This parameter optimization ensures the filaments have appropriate mechanical properties to withstand high stretching ratios (1.5 or more) without breaking, while still achieving the desired polymer orientation and strength in the final multifilament.
Solution Approach 2:
The patent implements preliminary action through the controlled cooling step performed before stretching. By cooling the undrawn multifilament to a specific temperature range (0-50°C) prior to stretching, the filaments are prepared in advance with optimal mechanical properties that enable them to survive the subsequent high-ratio stretching process and achieve high strength without breakage.
2Manufacturing precision
If the mean fineness of individual filaments is reduced to achieve thin filaments, then the fineness is improved, but the coefficient of variation increases making the multifilament unprocessable
Solution Approach 1:
The patent applies parameter changes by optimizing the cooling conditions (temperature range of 0-50°C and controlled cooling rate) to achieve a balance between mean fineness and uniformity. This parameter control ensures that even when producing thin filaments with low mean fineness (30 dtex or less), the coefficient of variation remains at 33% or less, maintaining processability.
Solution Approach 2:
The patent uses a spinning nozzle with 30 or more discharge holes to produce multiple filaments simultaneously with consistent dimensions. This copying approach ensures that each filament in the multifilament has uniform fineness, maintaining a low coefficient of variation (33% or less) even when the mean fineness is reduced to 30 dtex or less, thereby ensuring processability.
3Productivity
If the number of discharge holes in the spinning nozzle is increased to produce more filaments, then the productivity is improved, but the control of fineness uniformity becomes more difficult
Solution Approach 1:
The patent segments the production process by using a spinning nozzle with 30 or more discrete discharge holes, where each hole produces an individual filament. This segmentation allows for high productivity while maintaining uniformity, as each discharge hole operates independently under controlled cooling conditions (0-50°C), ensuring consistent fineness across all filaments with a coefficient of variation of 33% or less.
Solution Approach 2:
The patent employs a spinning nozzle with 30 or more discharge holes that replicate the same filament formation process simultaneously. This copying mechanism ensures that each filament is produced under identical conditions, maintaining fineness uniformity (coefficient of variation ≤33%) while achieving high productivity through parallel production of multiple filaments.
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 method enables the production of a multifilament with high strength and small mean fineness, overcoming the issue of filament breakage during stretching and achieving a stable, processable undrawn multifilament with improved mechanical properties.
Implementation Method 1
blowing a gas having a temperature of 0 to 50° C. onto the 30 or more raw filaments in the molten state to cool the 30 or more raw filaments
Implementation Method 2
the individual filaments contain a poly(3-hydroxyalkanoate) resin and a nucleating agent
Data Source
AI summary
The present invention is directed to an undrawn multifilament including 30 or more individual filaments. In the undrawn multifilament, the individual filaments contain a poly(3-hydroxyalkanoate) resin and a nucleating agent, the mean of the finenesses of the individual filaments is 30 dtex or less, and the coefficient of variation of the finenesses of the individual filaments is 33% or less.