Graphite-Filled Polyester for LED Housing Thermal Management
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Solution Overview
Problem
LED housings require improved thermal conductivity and ductility to manage heat effectively and prevent overheating, which is challenging due to the higher cost and complex current and heat management needs compared to compact fluorescent lamps.
Innovation Solution
A polyester composition comprising 3-40 weight percent polyester, 30-50 weight percent non-fibrous graphite, 10-40 weight percent inorganic filler, and 3-10 weight percent copolyether ester elastomer, providing a thermal conductivity of at least 3 WmK and tensile strength of at least 25 MPa, enabling efficient heat dissipation and mechanical durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high levels of graphite are added to polyester composition, then thermal conductivity is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent uses a composite material system consisting of polyester resin, graphite particles (30-50 wt%), and copolyether ester elastomer (3-10 wt%). This composite approach allows combining materials with different properties to achieve both high thermal conductivity from graphite and adequate mechanical strength through the polyester and elastomer matrix.
Solution Approach 2:
The patent optimizes the concentration of graphite particles to 30-50 wt% and copolyether ester elastomer to 3-10 wt% to achieve the desired balance between thermal conductivity and mechanical strength. This parameter optimization ensures sufficient thermal management while maintaining structural integrity.
2Temperature
If high levels of graphite are added to polyester composition, then thermal conductivity is improved, but ductility deteriorates
Solution Approach 1:
The patent optimizes the concentration of copolyether ester elastomer to 3-10 wt% to maintain ductility and elongation properties even with high graphite content (30-50 wt%). This parameter control ensures the material remains processable and maintains adequate elongation.
Solution Approach 2:
The copolyether ester elastomer components provide localized flexibility and ductility within the rigid graphite-polyester matrix, allowing the material to maintain elongation properties while achieving high thermal conductivity in other regions.
3Illumination intensity
If LED wattage is increased for ambient room lighting, then lighting output is improved, but heat management complexity increases
Solution Approach 1:
The patent extracts the heat management function from complex active cooling systems and integrates it into the housing material itself through high thermal conductivity graphite-filled polyester composition. This passive thermal management approach simplifies the overall LED lighting system while handling higher wattage outputs.
Solution Approach 2:
The graphite-filled polyester composition acts as an intermediary thermal management layer between the LED heat source and the external environment, facilitating heat dissipation without requiring complex active cooling systems.
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 a balance of thermal conductivity and tensile strength, preventing overheating and mechanical failure in LED housings, ensuring safe and reliable operation.
Implementation Method 1
These compositions have good ductility, especially terms of tensile elongation, and thermal conductivity
Implementation Method 2
a copolyether ester elastomer... at least 25 MPa tensile strength
Data Source
AI summary
Polyester compositions comprising:3 to 40 weight percent, preferably 3 to 30 weight percent, of at least one polyester, preferably polybutylene terephthalate, polytrimethylene terephthalate, polyethylene terephthalate, poly(ethylene 2,6-naphthoate), and poly(1,4-cyclohexyldimethylene terephthalate);25 to 50 weight percent non-fibrous graphite, preferably a platy or particulate graphite;10 to 40 weight percent inorganic filler selected from the group consisting of wollastonite, glass fibers, aramid fibers, ceramic fibers, potassium titanate whiskers, or combinations of them;3 to 10 weight percent copolyether ester elastomer;wherein:the amount of a+b+c+d is 100 weight percent of the composition;the amount of b+c is at least 50 weight percent of the composition; the weight ratio of copolyether ester elastomer to polyester is from 0.3 to 0.4; and the composition has at least a 0.2 percent elongation, a thermal conductivity of at least 3 WmK, and a tensile strength of at least 25 MPa. Articles prepared from these compositions.