Polyamide LED Compositions Retaining Reflectivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polymer compositions used in LED applications tend to yellow and lose reflectivity when exposed to high temperatures, which affects the performance and longevity of LED components.
Innovation Solution
A polyamide composition with specific properties, including low intrinsic melt viscosity and the combination of magnesium oxide, zinc oxide, and titanium dioxide, is developed to maintain high reflectivity and whiteness even after heat and light aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polymer compositions are used to replace ceramics in LED applications, then manufacturing cost is reduced, but heat resistance and retention of reflectivity at high temperature deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of polyphthalamide polymer combined with specific inorganic fillers (talc, glass fiber, wollastonite) and a unique stabilizer package (hindered phenol, phosphite, and hindered amine light stabilizer in specific ratios). This composite structure allows the polymer to achieve ceramic-like heat resistance while maintaining the cost advantages and processability of polymer materials.
2Ease of manufacture
If polymer compositions are used to replace ceramics in LED applications, then ease of processing is improved, but retention of reflectivity after heat exposure deteriorates
Solution Approach 1:
The patent optimizes the parameters of the stabilizer package by specifying precise weight ratio ranges: hindered phenol to phosphite at 1:0.3 to 1:2, and hindered phenol to hindered amine light stabilizer at 1:0.5 to 1:3. This parameter optimization ensures the composition maintains reflectivity above 80% after 1000 hours at 85°C and above 70% after 10 minutes at 260°C, while preserving good moldability and processing characteristics.
3Illumination intensity
If higher reflectivity is achieved through titanium dioxide content, then optical performance is improved, but yellowing resistance at high temperature deteriorates
Solution Approach 1:
The patent introduces phosphite as an intermediary substance that mediates between titanium dioxide and the polymer matrix. The phosphite acts as a synergistic stabilizer that protects titanium dioxide from thermal degradation and prevents catalytic yellowing, while allowing high TiO2 content (10-40 wt%) to be used for achieving reflectivity above 90% in the visible range.
4Ease of manufacture
If polycondensation polymers are used for LED components, then good moldability is achieved, but yellowing when exposed to light and heat occurs
Solution Approach 1:
The patent creates a composite stabilization system combining three types of stabilizers (hindered phenol, phosphite, and hindered amine light stabilizer) in specific ratios within the polyphthalamide matrix. This composite approach provides synergistic protection against both thermal degradation and photo-oxidation, maintaining yellowing resistance while preserving the inherent good moldability of polycondensation polymers.
Solution Approach 2:
The patent optimizes the concentrations and ratios of stabilizers to achieve maximum protection against yellowing. The specific weight ratios (hindered phenol:phosphite = 1:0.3 to 1:2; hindered phenol:hindered amine light stabilizer = 1:0.5 to 1:3) create an optimized chemical environment that prevents yellowing while maintaining processability.
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 provides improved retention of reflectivity, mechanical properties, and heat resistance, ensuring the performance and efficiency of LED components over time.
Implementation Method 1
Titanium dioxide (TiO 2 ) is extensively used in compositions used in LED applications as a white pigment. Such compositions exhibit superior properties for molding and the molded parts exhibit high thermal stability, including dimensional stability and retention of mechanical properties, during fabrication and end use. Retention of whiteness and reflectivity during processing and end use is also high.
Implementation Method 2
Typical compounds contain TiO 2 , a reinforcing filler (glass fiber or mineral fillers) and organic stabilizers (hindered phenols, phosphites and hindered amines light stabilizers).
Data Source
AI summary
The invention relates to polyamide composition comprising at least one polyamide featuring a melting temperature (Tm), at least one metal oxide selected from magnesium oxide, zinc oxide and calcium oxide, and titanium dioxide, said composition featuring an intrinsic melt viscosity of below 800 Pa.s as measured according to ASTM D3835-08 at a moisture content as measured according to ASTM D6869-03 in the range of 150-500 ppm at a shear rate of 400 s-1 and at a temperature ranging from [(Tm max) +10°C] to [(Tm max)+20°C] where (Tm max) is the highest of all melting temperatures(Tm). Invented compositions feature high reflectivity in the molded part with high retention of whiteness and reflectivity after heat aging. This unique combination of properties makes the compositions according to the invention most suitable for LED applications.