Recycled ABS Resin Extrusion for Polyurethane Impurity Removal
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Solution Overview
Problem
Existing methods for recycling ABS resin face challenges in maintaining the physical properties and appearance of the recycled product due to the presence of impurities, particularly polyurethane, which leads to surface deterioration and deformation.
Innovation Solution
A method involving the use of a hydrate of a metal carboxylic acid salt, such as zinc acetate or potassium acetate, in the extrusion process to depolymerize polyurethane, controlling the residence time and temperature to minimize heat exposure and promote efficient depolymerization, thereby preparing a recycled ABS resin with improved surface properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If waste ABS resin including polyurethane impurities is melted and pelletized by mechanical recycling, then the recycled resin can be produced, but surface properties deteriorate and deformation occurs due to impurities
Solution Approach 1:
The patent extracts and removes polyurethane impurities from waste ABS resin through a multi-step process involving dissolution in a specific solvent system (chloroform/methanol), filtration, and purification. This extraction process separates the harmful polyurethane components from the valuable ABS resin, enabling production of recycled resin with restored surface properties and minimal deformation.
Solution Approach 2:
The patent uses a solvent system (chloroform and methanol) as an intermediary medium to facilitate the separation of polyurethane from ABS resin. The specific solvent ratio and temperature conditions create an environment where polyurethane dissolves and can be filtered out, while ABS resin remains intact and can be recovered through precipitation and drying.
2Device complexity
If polyurethane is not removed from waste ABS resin, then the recycling process is simpler, but the recycled resin shows deterioration of physical properties and surface quality
Solution Approach 1:
The patent applies preliminary action by performing dissolution and separation of polyurethane impurities before the final pelletization step. The waste resin is first treated with solvent to dissolve polyurethane, then filtered to remove dissolved impurities, and finally dried and pelletized. This preliminary purification ensures that the subsequent molding process produces high-quality recycled resin with reliable physical properties.
3Ease of manufacture
If high temperature melting is used to process waste ABS resin, then the resin can be molded, but discoloration and deterioration of appearance properties occur
Solution Approach 1:
The patent changes the processing parameters from high-temperature direct melting to a lower-temperature solvent-based separation process followed by controlled drying. The resin is treated at moderate temperatures during dissolution and filtration, then dried at controlled temperatures (40-60°C) to prevent discoloration. This parameter change maintains ease of manufacture while preserving appearance properties.
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 effectively depolymerizes polyurethane, preventing surface deterioration and maintaining the physical properties of the recycled ABS resin, ensuring minimal discoloration and deformation.
Implementation Method 1
preparing an extrusion feed including an acrylonitrile butadiene styrene (ABS) base resin including polyurethane and a hydrate of a metal carboxylic acid salt, and supplying the extrusion feed to an extruder to perform a depolymerization reaction of the polyurethane
Implementation Method 2
supplying the extrusion feed to an extruder to perform a depolymerization reaction of the polyurethane and extrude the extrusion feed
Implementation Method 3
supplying the extrusion feed to an extruder to perform a depolymerization reaction of the polyurethane and extrude the extrusion feed
Data Source
AI summary
Provided is a method for preparing a recycled ABS resin including: preparing an extrusion feed including an acrylonitrile butadiene styrene (ABS) base resin including polyurethane and a metal carboxylic acid salt or a hydrate of the metal carboxylic acid salt, and supplying the extrusion feed to an extruder to perform a depolymerization reaction of the polyurethane and extrude the extrusion feed, wherein a master index (M) value satisfies 0.2≤M≤0.6.