Liquid Crystal Polyester Resin for LED Reflector
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Solution Overview
Problem
Conventional liquid crystal polyester resin compositions used for LED reflectors are prone to discoloration under LED light, leading to decreased light reflectance and efficiency.
Innovation Solution
A liquid crystal polyester resin composition containing p-hydroxybenzoic acid, cyclohexane dicarboxylic acid, and titanium oxide, with specific mole percentages and two-stage polymerization, is developed to enhance light reflectance, heat resistance, and mechanical properties, reducing discoloration and maintaining reflectance even after light irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid crystal polyester resin compositions are used for LED reflectors, then the reflector can be manufactured with good molding processability and heat resistance, but the reflector surface is easily discolored by LED light, causing decreased light reflectance and LED brightness
Solution Approach 1:
The patent changes the chemical composition parameters of the liquid crystal polyester by incorporating specific repeating structural units (formulas 1-4) with controlled mole percentages. This chemical parameter modification enhances the polymer's resistance to light-induced discoloration while preserving its heat resistance and molding properties, directly resolving the contradiction between reliability under heat and resistance to light-induced degradation
Solution Approach 2:
The patent creates a composite resin composition by blending liquid crystal polyester with specific inorganic fillers (titanium oxide, zinc oxide, silicon oxide) and UV absorbers. This composite structure combines the heat resistance of the polyester with the light-stability and UV-absorption properties of the inorganic additives, achieving both heat resistance and resistance to discoloration simultaneously
2Power
If the power of LEDs is increased to improve light output, then the light energy received by reflectors increases, but this exacerbates the discoloration problem and reduces light reflectance over time
Solution Approach 1:
The patent converts the harmful effect of high-energy LED light into a beneficial outcome by incorporating UV absorbers and light-stable inorganic fillers that actively absorb and dissipate the excess light energy. These additives sacrifice themselves to protect the reflector material, converting the potentially harmful high-power LED radiation into harmless heat through controlled absorption, thereby maintaining light reflectance even under high-power operation
Solution Approach 2:
The patent modifies the optical absorption parameters of the reflector material by adding specific inorganic fillers and UV absorbers with controlled concentrations. This parameter change enables the material to safely handle higher light energy loads by adjusting its absorption characteristics, allowing the system to utilize higher-power LEDs without accelerating discoloration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition achieves high light reflectance, minimal discoloration, and excellent heat resistance, ensuring the LED reflector maintains performance and withstands solder reflow, suitable for high-power LEDs.
Implementation Method 1
a resin composition comprising a liquid crystal polyester containing p-hydroxybenzoic acid (HBA) in a particular amount and cyclohexane dicarboxylic acid (CHDA) in a particular amount as a constituent of a polyester, and titanium oxide in a particular amount
Implementation Method 2
the light reflectance of the reflector decreases, and LED brightness decrease (decrease in light extraction efficiency) occurs
Implementation Method 3
a liquid crystalline polyester having an adamant molecular structure and exhibiting optical anisotropy during melting to bring excellent flowability
Implementation Method 4
exhibiting optical anisotropy during melting to bring excellent flowability
Implementation Method 5
heat resistance withstanding soldering is also required... sufficiently high distortion temperature under load (DTUL)... the DTUL is preferably 220° C. or more
Data Source
AI summary
A liquid crystal polyester resin composition of the present invention comprises: 100 parts by mass of a liquid crystal polyester; and 50 to 150 parts by mass of titanium oxide, wherein the liquid crystal polyester comprises 2 to 30 mole % of a repeating structural unit represented by the following formula (1), and 40 to 80 mole % of a repeating structural unit represented by the following formula (2).