Curable Organopolysiloxane for LED Packaging
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Solution Overview
Problem
Existing curable organopolysiloxane compositions for packaging materials, such as those used in light emitting diodes, face issues with high viscosity, poor adhesive properties, and the generation of nonreactive residues like methyl phenyl rings, leading to sticky surfaces and yellowing during high-temperature curing.
Innovation Solution
A curable composition comprising an organopolysiloxane with at least two silicon-bonded alkenyl groups, a branched organopolysiloxane, and a siloxane capped with H, along with a catalyst, which eliminates low molecular weight residue issues and provides a cured product with improved heat resistance, refractive index, and transmittance, allowing for quick curing and adjustable structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a curable organopolysiloxane composition with silicon-bonded phenyl groups and alkenyl groups is used, then the cured product has high refractive index and transmittance, but the composition has high viscosity causing operation difficulty and poor adhesive property
Solution Approach 1:
The patent modifies the polysiloxane structure by changing the ratio of phenyl groups to alkenyl groups, and by introducing linear organopolysiloxane components with different molecular weights, to achieve optimal balance between refractive index and viscosity. This structural parameter adjustment allows the composition to maintain high optical properties while improving processability and adhesion.
2Ease of operation
If a linear organopolysiloxane with silicon-bonded alkenyl groups and aryl groups is used to reduce viscosity, then the cured product has low viscosity and good adhesive property, but nonreactive residue of methyl phenyl rings is generated making the surface sticky
Solution Approach 1:
The patent carefully controls the content of aryl groups and the ratio of alkenyl groups to prevent excessive formation of nonreactive methyl phenyl ring residues. By adjusting these compositional parameters, the cured product achieves low viscosity and good adhesion without developing a sticky surface.
Solution Approach 2:
The patent creates a composite system combining linear organopolysiloxane with crosslinking agents and catalysts, where the interaction between components prevents residue accumulation. The composite formulation ensures complete reaction of alkenyl groups while maintaining low viscosity and non-sticky surface properties.
3Object-generated harmful factors
If high-temperature distillation is used to remove nonreactive rings, then the residue is removed, but the bonding between phenyl groups breaks resulting in yellowing
Solution Approach 1:
Instead of using high-temperature distillation that causes yellowing, the patent converts the potential harm of phenyl group decomposition into a benefit by designing a composition where phenyl groups are properly protected through optimal crosslinking. The alkylation reaction conditions are optimized to prevent bond breakage while still removing residues, transforming a harmful process into a beneficial one.
Solution Approach 2:
The patent changes the reaction parameters including temperature, catalyst type, and composition ratios to enable residue removal without phenyl group decomposition. By controlling these parameters, the curing process eliminates sticky residues while maintaining color stability and preventing yellowing.
4Ease of operation
If a linear organopolysiloxane with insufficient strength is used, then the composition has low viscosity, but the cured product fractures under high temperature or drastic temperature variation
Solution Approach 1:
The patent creates a composite structure by combining linear organopolysiloxane with crosslinking agents that form a three-dimensional network. This composite architecture provides both low viscosity for easy processing and high thermal stability for resistance to fracture under temperature stress.
Solution Approach 2:
The patent introduces crosslinking points at strategic locations within the polymer structure, creating local regions of enhanced strength and thermal stability while maintaining the overall low viscosity characteristic of linear polysiloxanes. This localized reinforcement prevents fracture without compromising 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 achieves a cured product with low viscosity, excellent adhesive properties, high refractive index, and resistance to yellowing at high temperatures, making it suitable for optical materials like LED packaging without the drawbacks of sticky surfaces or color changes.
Implementation Method 1
An organic silicon resin, i.e., organopolysiloxane, can be cured through alkylation with silicon hydrides
Implementation Method 2
a curable organopolysiloxane composition, comprising an organopolysiloxane in which each molecule has a silicon-bonded phenyl group and an silicon-bonded alkenyl group, an organic hydrogen siloxane, and an alkylation catalyst
Data Source
AI summary
A curable composition comprises the following: (A) a polymer having at least two silicon-bonded alkenyl groups and having an average unit formula (I′):(R12SiO2/2)a1(R23SiO1/2)b1(CH2CH2)e1;(B) a branched organopolysiloxane having at least one silicon-bonded alkenyl group and having a siloxane unit of formula R4SiO3/2; (C) an organopolysiloxane having an average unit formula (II) being capped with H: (R52SiO2/2)f(R63SiO1/2)g(R7SiO3/2)h(SiO4/2)i(CH2CH2)j; and (D) a catalyst, wherein R1, R2 and R4 to R7 and a1, b1, e1 and f to j are as defined in the specification.