Polyethylene Resin Injection Suitability Prediction
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Solution Overview
Problem
Current methods for injection molding of plastic resins lack accurate prediction of injection pressure and suitability, leading to issues such as incomplete injection due to pressure being below a certain range or deteriorated processability when above a certain range.
Innovation Solution
A method involving measuring the number average molecular weight and fraction of low molecular weight molecules in a plastic resin specimen to predict injection suitability and pressure, using a polyethylene resin with specific molecular weight characteristics and rheological properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If injection pressure is increased to ensure complete injection, then injection reliability is improved, but processability deteriorates due to excessive pressure
Solution Approach 1:
The patent performs preliminary measurement of molecular weight and low molecular weight content in the resin before injection molding. These measurements are used to predict the appropriate injection pressure range in advance, allowing the process to be optimized before actual production, thus avoiding both incomplete injection and excessive pressure damage.
Solution Approach 2:
The patent establishes specific parameter ranges for molecular weight (10,000-30,000 g/mol) and low molecular weight content (2-10%) as predictive indicators. By controlling these resin parameters within specified ranges, the injection pressure can be optimized to achieve both complete injection and good processability without trial and error.
2Measurement precision
If direct injection testing is performed to determine injection pressure, then accuracy of pressure determination is improved, but time consumption and cost increase
Solution Approach 1:
The patent uses molecular weight and low molecular weight content as surrogate indicators that copy the resin's flow behavior characteristics. Instead of performing actual injection tests to measure pressure, these measurable resin properties serve as proxies to predict injection pressure accuracy, dramatically reducing time and cost while maintaining predictive capability.
Solution Approach 2:
The patent replaces the mechanical injection testing system with a chemical characterization system. By measuring molecular weight distribution through analytical methods rather than physical injection tests, the system substitutes complex mechanical evaluation with simpler chemical analysis, achieving the same predictive goal with less time and resources.
3Ease of manufacture
If injection pressure is set too low to maintain processability, then resin flow is smooth, but incomplete injection occurs due to boundary layer formation
Solution Approach 1:
The patent performs preliminary characterization of the resin's molecular weight and low molecular weight content before injection molding. This advance knowledge allows prediction of the resin's flow behavior and boundary layer formation characteristics, enabling optimization of injection pressure to ensure complete injection while maintaining smooth flow.
Solution Approach 2:
The patent establishes specific parameter ranges for molecular weight (10,000-30,000 g/mol) and low molecular weight content (2-10%) that optimize the balance between resin flow smoothness and injection completeness. By controlling these parameters, the resin exhibits favorable flow characteristics that reduce boundary layer effects while ensuring complete mold filling.
Data Source
AI summary
The present invention relates to a method for evaluating an injection physical property of a plastic resin, and a polyethylene resin suitable for an injection molding process and, more particularly, to a novel method for evaluating an injection physical property of a plastic resin, which, when a particular plastic resin is processed by an injection process, can accurately derive injection suitability of the plastic resin and injection pressure in the injection process through a physical property value measured by using a resin specimen, and a polyethylene resin suitable for injection molding.