Low-Silicon Recycled Polyamide for Clog-Resistant Melt Spinning
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Solution Overview
Problem
Polyamide compositions used in recycling processes are prone to clogging during melt processing, leading to equipment downtime, and recycled polyamide fibers exhibit non-uniform aging-related shrinkage, causing weaving defects in airbag base fabrics.
Innovation Solution
A polyamide composition with controlled silicon and oligomer content, processed using a specific dissolution method to minimize residual silicone and optimize polymerization degree, reducing clogging and enhancing fiber uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If material recycling is used to recycle polyamide, then resource conservation is achieved, but quality instability occurs due to degradation of polymers and additives
Solution Approach 1:
The patent extracts and removes contaminants (silicone resin, coatings, and other additives) from the recycled polyamide through a specific dissolution process using calcium chloride methanol solution, thereby obtaining purified polyamide that maintains quality stability while still benefiting from material recycling's lower energy consumption compared to chemical recycling
2Strength
If silicone coating is applied to polyamide base fabric, then durability against rupture is improved, but clogging during melt processing occurs
Solution Approach 1:
The patent removes the harmful silicone coating from the polyamide base fabric through dissolution in calcium chloride methanol solution, separating the silicone resin from the polyamide matrix. This extraction eliminates the clogging issue during melt processing while preserving the structural integrity and strength benefits of the original polyamide material
Solution Approach 2:
The patent changes the chemical state of the silicone coating from a bonded surface layer to a dissolved and separated phase through controlled dissolution conditions. By adjusting the dissolution parameters (temperature, solvent concentration, treatment time), the silicone is effectively removed without degrading the polyamide base material, thereby eliminating clogging while maintaining material strength
3Reliability
If dissolution method using ethylene glycol is used to remove contaminants, then purification is achieved, but glycolysis of polyamide occurs and significant energy is required for solvent distillation
Solution Approach 1:
The patent changes the solvent system from ethylene glycol (which causes glycolysis and requires high-temperature distillation) to calcium chloride methanol solution. This parameter change eliminates the chemical degradation issue while reducing the energy required for solvent removal, as the calcium chloride methanol solution can be removed through evaporation at lower temperatures and the calcium chloride can be filtered out
Solution Approach 2:
The patent uses a disposable or recyclable calcium chloride methanol solution system that can be easily separated from the polyamide through filtration and evaporation. The calcium chloride acts as a temporary agent that facilitates contaminant removal but can be completely separated, avoiding the need for energy-intensive distillation processes required by ethylene glycol methods
4Loss of energy
If low-temperature dissolution method using calcium chloride methanol solution is used, then energy consumption is reduced, but filter clogging occurs during spinning
Solution Approach 1:
The patent thoroughly extracts and removes all contaminants including silicone resin, coatings, and other additives from the polyamide through extended dissolution treatment with calcium chloride methanol solution. By ensuring complete removal of these harmful substances before spinning, the patent eliminates filter clogging while maintaining the energy efficiency of the low-temperature dissolution method
Solution Approach 2:
The patent performs preliminary dissolution and purification treatment before the spinning process to remove all potential clogging agents. By conducting the contamination removal step in advance through calcium chloride methanol solution treatment, the patent ensures that the subsequent spinning process proceeds without filter clogging, thereby enabling continuous operation
5Loss of energy
If recycled polyamide is used for airbag base fabric, then resource conservation is achieved, but non-uniform aging-related shrinkage causes weaving defects
Solution Approach 1:
The patent extracts and removes contaminants that cause non-uniform shrinkage through dissolution treatment. By removing silicone resin, coatings, and other additives that create heterogeneous structures within the polyamide, the patent achieves uniform aging-related shrinkage behavior, thereby eliminating weaving defects while maintaining resource conservation benefits
Solution Approach 2:
The patent changes the chemical composition and molecular structure of the recycled polyamide through controlled dissolution and reprecipitation processes. This parameter change homogenizes the material structure, ensuring uniform shrinkage characteristics during aging that prevent weaving defects in the final airbag base fabric
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 long-term continuous operation of processing equipment and improves the quality of airbag base fabrics by minimizing clogging and uniformity issues.
Implementation Method 1
a dissolution method using an alcohol solution of calcium chloride can be mentioned. For example, PTL 4 discloses a method in which polyamide fabric coated with silicone is treated with a calcium chloride methanol solution to dissolve the polyamide
Implementation Method 2
the polyamide is then precipitated and recovered by some methods
Data Source
AI summary
According to the present disclosure, a polyamide composition that is less prone to clogging in the flow paths such as filters in a processing apparatus during melt processing such as melt spinning, and allows for long-term continuous operation of a processing apparatus can be provided. A polyamide composition is provided which is a recycled polyamide composition containing a silicon compound and having a silicon atom content as quantified by X-ray fluorescence analysis of 1000 ppm or less.