Polycarbonate Resin Composition for Light Guide Plates
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Solution Overview
Problem
Polycarbonate resin compositions used for light guide plates in display devices face challenges with low light transmittance, brightness, yellowing, reduced heat resistance, and increased gas generation and mold contamination during high-temperature injection molding, which affect the optical and mechanical properties of the molded articles.
Innovation Solution
A polycarbonate resin composition is developed by blending a conventional polycarbonate resin with specific quantities of a phosphorus-containing stabilizer and a polycarbonate copolymer having carbonate bonding between bisphenol A and polyalkylene glycol, which improves impact resistance, hue, and reduces gas generation and mold contamination during molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polycarbonate resin is used to replace conventional resin materials for light guide plates, then heat resistance is improved, but light transmittance and brightness deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of polycarbonate resin blended with specific additives including phosphorus-containing stabilizers and aromatic amine compounds. This composite approach maintains the heat resistance of polycarbonate while mitigating its poor light transmittance through synergistic interactions between components that suppress yellowing and maintain optical clarity.
Solution Approach 2:
The patent modifies the chemical composition parameters of polycarbonate resin by incorporating specific ratios of phosphorus-containing stabilizers (0.01-1.0 part by mass per 100 parts of polycarbonate) and aromatic amine compounds (0.1-5.0 parts by mass per 100 parts of polycarbonate). These parameter changes optimize both thermal stability and optical properties simultaneously.
2Strength
If polycarbonate resin is used for light guide plates, then mechanical properties are improved, but yellowing occurs affecting hue
Solution Approach 1:
The patent converts the inherent susceptibility of polycarbonate to yellowing into a benefit by using phosphorus-containing stabilizers that preferentially react with degradation products causing yellowing. The stabilizers transform harmful oxidation products into harmless compounds, maintaining both mechanical strength and optical clarity throughout the service life.
Solution Approach 2:
The patent introduces phosphorus-containing stabilizers and aromatic amine compounds as intermediary substances that mediate between the polycarbonate resin and environmental factors causing yellowing. These intermediaries absorb UV radiation and free radicals, preventing direct damage to the polycarbonate chains and maintaining hue stability while preserving mechanical properties.
3Productivity
If high barrel temperatures and high injection speeds are used for molding light guide plates, then productivity is improved, but gas generation and mold contamination increase
Solution Approach 1:
The patent incorporates phosphorus-containing stabilizers and aromatic amine compounds into the polycarbonate resin before molding to perform preliminary protection against thermal degradation. These additives preemptively neutralize degradation tendencies during high-temperature injection molding, allowing high productivity operation without generating excessive gas or causing mold contamination.
Solution Approach 2:
The patent converts the potential harm of high-temperature processing into a benefit by using stabilizers that become more effective at higher temperatures. The phosphorus-containing stabilizers and aromatic amine compounds undergo beneficial thermal reactions that suppress gas generation and prevent mold contamination, enabling high-speed molding with clean results.
Data Source
AI summary
A polycarbonate resin composition containing 0.1 to 10 parts by mass of a polycarbonate copolymer (B) having carbonate bonding between (B1) bisphenol A and a (B2) polyalkylene glycol and 0.005 to 0.5 parts by mass of a phosphorus-containing stabilizer (C) relative to 100 parts by mass of a polycarbonate resin (A).