Polyester Resin Composition for LED Reflector Light Stability
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Solution Overview
Problem
Thermoplastic polyester resins used in lighting display devices face challenges with reduced impact resistance and moldability when white pigments and fillers are added, leading to decreased light stability and mechanical properties at high temperatures.
Innovation Solution
A polyester resin composition comprising a high-melting aromatic polyester resin, a low-melting copolyester resin, white pigment, and inorganic filler, specifically formulated to maintain mechanical properties and light stability while minimizing yellowness index change and reflectivity changes at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If white pigments and fillers are added to polyester resins to improve heat resistance and discoloration resistance, then thermal stability is improved, but impact strength and moldability are dramatically reduced
Solution Approach 1:
The patent uses a composite resin system combining thermoplastic polyester resin and thermosetting polyester resin in specific ratios (30-70 wt% and 70-30 wt% respectively). This composite approach allows the thermosetting component to provide enhanced heat resistance and discoloration resistance while the thermoplastic component maintains impact strength and moldability, resolving the contradiction between thermal stability and mechanical properties.
2Reliability
If white pigments and fillers are added to polyester resins to improve discoloration resistance, then light stability is improved, but mechanical properties are reduced
Solution Approach 1:
The dual-polyester resin composite system provides synergistic effects where the thermosetting polyester resin enhances light stability and discoloration resistance through its crosslinked network structure, while the thermoplastic polyester resin contributes to maintaining mechanical integrity and impact resistance, thus resolving the contradiction between light stability and mechanical properties.
3Illumination intensity
If white pigments and fillers are added to polyester resins to improve reflectivity, then optical efficiency is improved, but moldability is dramatically reduced
Solution Approach 1:
The thermoplastic polyester resin component provides good flow characteristics and moldability during processing, while the thermosetting polyester resin component enhances the final reflectivity and optical efficiency. The specific weight ratio range (30-70 wt% thermoplastic to 70-30 wt% thermosetting) balances the processing ease with the optical performance requirements.
Data Source
AI summary
A polyester resin composition comprises: (A) a first polyester resin having a melting temperature of greater than about 285° C.; (B) a second polyester resin having a melting temperature of less than or equal to about 285° C.; (C) a white pigment; and (D) an inorganic filler. The polyester resin composition may exhibit improved mechanical properties and discoloration resistance and can be used in a molded article, for example, as a LED reflector.