Recycled PET Flake Processing for Injection Molding
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Solution Overview
Problem
The direct use of post-consumer recycled polymeric flake in injection molding processes is challenging due to high contaminant levels and attributes like bulk density and moisture, requiring expensive melt filter systems and specialized extrusion systems.
Innovation Solution
A method involving the separation of ferrous and non-ferrous metals, comminution to specific particle sizes, thermal treatment to reduce moisture, and mixing with virgin pellets for processing in injection molding systems, potentially with inline filtration, to enable the use of high percentages of recycled flake directly in injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PCR polymeric flake is used directly in injection molding, then cost reduction is achieved, but high contaminant levels and moisture content cause processing problems
Solution Approach 1:
The patent applies preliminary action by performing metal separation, comminution to specific particle sizes (0.5-5mm), and thermal drying treatment before the injection molding process. This pre-processing removes contaminants and reduces moisture content in advance, enabling direct use of PCR flake without requiring expensive melt filters or specialized extrusion systems during molding
Solution Approach 2:
The patent changes physical parameters of the PCR flake through controlled comminution (reducing particle size to 0.5-5mm) and thermal treatment (drying at elevated temperatures). These parameter changes improve flow characteristics and reduce moisture content, allowing the flake to be processed directly in standard injection molding equipment without additional contamination control systems
2Object-affected harmful factors
If melt filter systems are used to handle PCR flake contamination, then contamination is reduced, but equipment cost and complexity increase
Solution Approach 1:
The patent extracts harmful metal contaminants from the PCR flake through magnetic and eddy current separation before processing. By removing these contaminants in advance, the need for complex melt filter systems during injection molding is eliminated, allowing standard equipment to be used
Solution Approach 2:
Metal separation and comminution are performed as preliminary actions before injection molding. This pre-cleaning approach removes contaminants that would otherwise require expensive filtration systems during the molding process, simplifying the overall equipment requirements
3Object-affected harmful factors
If specialized twin screw extrusion systems with vacuum venting are used, then moisture and bulk density issues are addressed, but equipment cost increases
Solution Approach 1:
Thermal drying treatment is applied as a preliminary action to remove moisture from the PCR flake before injection molding. This pre-drying eliminates the need for vacuum venting systems and specialized extrusion equipment, allowing moisture control to be achieved through simple thermal treatment
Solution Approach 2:
The patent changes the moisture content parameter through controlled thermal drying and adjusts particle size through comminution to 0.5-5mm. These parameter changes improve bulk density and flow characteristics, enabling processing in standard injection molding equipment without specialized extrusion systems
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
This approach reduces costs, improves final article color and IV, minimizes yield loss, and decreases drying time, allowing for efficient and cost-effective processing of recycled flake without the need for pelletizing.
Implementation Method 1
separating ferrous and non-ferrous metals from the bulk of flakes of PCR plastic
Implementation Method 2
separating ferrous and non-ferrous metals from the bulk of flakes of PCR plastic
Implementation Method 3
comminuting the flake to a particle size less than 10 mm
Implementation Method 4
thermally treating the flake to reduce a moisture content therein
Implementation Method 5
thermally treating the flake to reduce a moisture content therein
Implementation Method 6
processing the mixture of flakes of PCR plastic and virgin plastic pellets in an injection molding system
Data Source
AI summary
A method of processing PCR plastic is disclosed, the method including a step of providing a bulk quantity of flakes of PCR plastic having a particle size of about 10 mm or larger separating ferrous and non-ferrous metals from the bulk of flakes of PCR plastic, comminuting the flake to a particle size less than 10 mm, such as about 4 mm, and thermally treating the flake to reduce a moisture content therein. The process may further including mixing the thermally treated flake with virgin plastic pellet and processing the mixture directly in an injection molding device.