Addition-Curable Silicone Composition for Optical Elements
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Solution Overview
Problem
Existing addition-curable silicone compositions for optical elements face challenges in achieving high transparency, refractive index, and strength characteristics, particularly with unsatisfactory optical transmission at 400nm wavelength and brittleness issues.
Innovation Solution
A specific addition-curable silicone composition comprising linear and branched organopolysiloxanes with CF3—(CF2)y—(CH2)z— groups, an organosilicon compound, and a platinum group metal-based catalyst, optimized to provide a cured product with a low refractive index, high transparency, and improved strength, enhancing optical transmission and light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a copolymer of dimethylsiloxane and diphenylsiloxane or polymethylphenylsiloxane is used as main backbone to achieve high refractive index (1.54 or more), then the refractive index is improved, but the cured product becomes difficult to synthesize and lacks elasticity
Solution Approach 1:
The patent changes the chemical composition parameters by introducing CF3-(CF2)y-(CH2)z- groups into the polysiloxane structure, which fundamentally alters the refractive index from the conventional 1.54 or higher down to 1.40 or lower, while simultaneously maintaining elasticity through the specific molecular architecture
Solution Approach 2:
The patent creates a composite material system combining linear organopolysiloxane (A) with branched organopolysiloxane (B) and organosilicon compound (C), where each component contributes specific properties: (A) provides base elasticity and transparency, (B) enhances strength through branching structure, and (C) enables crosslinking while maintaining optical properties, achieving a balance between refractive index, elasticity, and strength
2Temperature
If a branched polysiloxane with phenyl group is used to achieve refractive index of 1.53 to 1.54, then the refractive index is improved, but the cured product becomes hard resin and less elastic
Solution Approach 1:
The patent fundamentally changes the chemical structure by replacing phenyl groups with CF3-(CF2)y-(CH2)z- groups, which have different optical and mechanical properties, achieving low refractive index (≤1.40) while maintaining elasticity through the fluorinated alkyl chain structure
Solution Approach 2:
The patent introduces specific CF3-(CF2)y-(CH2)z- groups at controlled ratios (1-50 mol%) into the polysiloxane chain, creating local regions with desired optical properties while the overall polymer structure maintains elasticity through the siloxane backbone and crosslinking network
3Temperature
If composition is optimized for high transparency and high refractive index, then optical properties are improved, but the optical transmission with wavelength of 400 nm at 25°C becomes unfavorable
Solution Approach 1:
The patent changes the chemical composition by incorporating CF3-(CF2)y-(CH2)z- groups which have low polarizability and do not absorb in the UV-blue region, achieving both low refractive index (≤1.40) and high optical transmission at 400nm through the specific fluorinated structure
Solution Approach 2:
The patent uses simple fluorinated alkyl groups (CF3-(CF2)y-(CH2)z-) that can be readily synthesized and incorporated into the polysiloxane structure, achieving superior optical properties at 400nm without complex molecular designs
4Strength
If conventional silicone composition is used to achieve satisfactory strength characteristic, then mechanical properties are improved, but the transparency and refractive index fail to meet requirements
Solution Approach 1:
The patent creates a composite system where linear organopolysiloxane (A) provides base optical properties and elasticity, branched organopolysiloxane (B) enhances strength through its branching structure, and organosilicon compound (C) provides crosslinking for mechanical strength, achieving simultaneous optimization of transparency, refractive index, and strength
Solution Approach 2:
The patent introduces branched structures and crosslinking points at specific ratios (1-100 parts (B) and controlled SiH to unsaturated group ratio of 0.2-5.0) into the linear polysiloxane matrix, creating local regions that enhance strength while the overall structure maintains optical transparency and low refractive index
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 excellent optical transmission and strength characteristics, with refractive index below 1.40, significantly improving LED luminance and optical element performance, particularly at 400nm wavelength, while maintaining heat and electric insulation properties.
Implementation Method 1
An addition-curable silicone composition comprises a polyorganosiloxane containing an aliphatic unsaturated group such as an alkenyl group, and provides a cured product obtained by curing the polyorganosiloxane from hydrosilylation reaction
Implementation Method 2
a platinum group metal-based catalyst
Data Source
AI summary
An addition-curable silicone composition that provides a cured product having a particularly high transparency, an excellent light extraction efficiency and a favorable strength characteristic by subjecting the cured product to a lower refractive index by using a specific composition. The present invention was accomplished by an addition-curable silicone composition, including at least:(A) a linear organopolysiloxane having 2 or more aliphatic unsaturated groups bonded to a silicon atom and 1 or more CF3—(CF2)y—(CH2)z— groups bonded to a silicon atom in one molecule;(B) an organopolysiloxane having 2 or more aliphatic unsaturated groups bonded to a silicon atom and 1 or more CF3—(CF2)y—(CH2)z— groups bonded to a silicon atom in one molecule and having a branch structure of a siloxane unit represented by an SiO4/2 and/or an RSiO3/2;(C) an organosilicon compound represented by the following general formula (1); and(D) a platinum group metal-based catalyst.