Polyester Resin Composition for LED Reflectors
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Solution Overview
Problem
Polyester resin used in LED components faces challenges with yellowing, impact resistance, and reflectance deterioration under high heat and humidity conditions, particularly when compared to liquid crystal polymers, which exhibit unevenness and deterioration over time.
Innovation Solution
A polyester resin composition comprising high heat-resistant polyester resin with a main chain derived from aromatic dicarboxylic acid and cycloaliphatic diol, combined with white pigments and polyolefin copolymers, which provides excellent yellowing resistance, impact strength, and maintain reflectance without heat resistance deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid crystal polymer (LCP) is used for high heat resistance, then heat resistance is improved, but deterioration and unevenness occur over time
Solution Approach 1:
The patent modifies the polyester resin composition by controlling the molar ratio of cyclic aliphatic diol (15-85 mol%) and aromatic diol (15-85 mol%), and by controlling the intrinsic viscosity (0.4-1.5 dl/g) to achieve both heat resistance and long-term stability without the deterioration issues of LCP
Solution Approach 2:
The patent uses a composite resin system combining modified polyester resin with specific diol components to achieve the properties of LCP (heat resistance) while avoiding its drawbacks (deterioration and unevenness), effectively creating a superior composite material solution
2Productivity
If modified polyester resin is used to substitute LCP, then productivity is improved, but yellowing occurs under high heat and humidity
Solution Approach 1:
The patent controls the intrinsic viscosity of the polyester resin within 0.4-1.5 dl/g and adjusts the molar ratio of cyclic aliphatic diol (15-85 mol%) to aromatic diol (15-85 mol%) to prevent yellowing while maintaining manufacturing efficiency, resolving the contradiction between productivity and yellowing resistance
3Temperature
If high heat resistant polyester resin is used, then heat resistance is improved, but impact resistance deteriorates
Solution Approach 1:
The patent controls the intrinsic viscosity within 0.4-1.5 dl/g and adjusts the diol composition (cyclic aliphatic diol 15-85 mol% + aromatic diol 15-85 mol%) to achieve a balance between heat resistance and impact resistance, preventing the brittleness that typically accompanies high heat resistance
Solution Approach 2:
The patent creates a composite resin system with specific diol components that combines the heat resistance of aromatic polyesters with the flexibility and impact resistance of cyclic aliphatic diols, achieving both properties simultaneously
4Illumination intensity
If white pigment is added to improve reflectance, then reflectance is improved, but yellowing resistance deteriorates
Solution Approach 1:
The patent controls the intrinsic viscosity (0.4-1.5 dl/g) and diol composition to maintain resin stability that resists yellowing, allowing the use of white pigment (5-70 parts by weight) to achieve high reflectance (90% or more) without significant yellowing deterioration
Data Source
AI summary
The polyester resin composition of the present invention is characterized by comprising: (A) 100 parts by weight of a high heat resistant polyester resin having a main chain formed by a structure derived from aromatic dicarboxylic acid and alicyclic diol, wherein the melting point of the high heat resistant polyester resin is 200° C. or more; (B) 0.1 to 80 parts by weight of white pigment; and (C) 1 to 40 parts by weight of polyolefin copolymer. The resin composition of the present invention further comprises 1 to 40 parts by weight of a high stiffness polyester resin having a main chain comprising a structure derived from aromatic dicarboxylic acid and aliphathic diol. The molding foam, which is obtained from the polyester resin composition and the manufactured polyester resin composition, has good flexibility, heat resistance, and yellowing resistance and can be used for an LED reflecting plate due to having improved impact strength.