Thermoplastic Resin Composition for LED Light Stability
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Solution Overview
Problem
Thermoplastic resin compositions used in illuminating display devices, such as LEDs, face challenges in maintaining reflectance and light efficiency over long periods at high temperatures and high humidity conditions, with existing solutions compromising mechanical properties or long-term stability.
Innovation Solution
A thermoplastic resin composition comprising a polyester resin, a white pigment, and a sodium phosphate salt, specifically sodium pyrophosphate or sodium hexametaphosphate, which enhances reflectance, light efficiency, and discoloration resistance while maintaining mechanical properties and moldability, even under prolonged exposure to high temperature and humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light stabilizer additive is mixed into the resin to improve light stability and discoloration resistance, then light stability is improved, but mechanical properties are deteriorated
Solution Approach 1:
The patent uses a specific polyester resin composition as an intermediary medium that inherently provides light stability without requiring harmful additives. The polyester resin with controlled molecular weight and composition acts as a mediator between the requirement for light stability and the need to maintain mechanical properties, eliminating the need for light stabilizer additives that would compromise mechanical strength.
Solution Approach 2:
The patent changes the parameters of the polyester resin itself, specifically controlling the molecular weight (intrinsic viscosity of 0.4-1.5 dl/g) and composition (ratio of aromatic dicarboxylic acid to diol components), to achieve light stability intrinsically. This parameter optimization allows the resin to resist discoloration and maintain mechanical properties simultaneously, without adding light stabilizers.
2Temperature
If high heat resistant polyester resin is used to maintain heat resistance and discoloration resistance, then heat resistance is improved, but long term light stability under high temperature and high humidity conditions is deteriorated
Solution Approach 1:
The patent optimizes specific parameters of the polyester resin including intrinsic viscosity (0.4-1.5 dl/g) and the ratio of aromatic dicarboxylic acid to diol components (1:4 to 4:1). These parameter changes enable the resin to maintain both heat resistance and long-term light stability under high temperature and humidity conditions, resolving the contradiction between heat resistance and light stability.
Solution Approach 2:
The patent creates a composite resin system by combining polyester resin with specific additives (0.1-10 parts by weight of light stabilizer and 10-60 parts by weight of white pigment based on 100 parts by weight of base resin). This composite approach enhances long-term light stability while preserving heat resistance properties.
Data Source
AI summary
A thermoplastic resin composition that can have high reflectance and light efficiency and excellent discoloration resistance even at high temperature and high humidity conditions over a long period of time includes (A) a polyester resin; (B) a white pigment; and (C) a sodium phosphate salt.