Addition-Curable Silicone Composition for Optical Encapsulation
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Solution Overview
Problem
Conventional addition-curable silicone compositions for optical purposes face issues with insufficient temperature cycling resistance, peeling from substrates, and crack generation, while also failing to achieve high refractive index and transparency.
Innovation Solution
An addition-curable silicone composition comprising a three-dimensional network organopolysiloxane with alkenyl and aryl groups, a linear organopolysiloxane with multiple alkenyl and aryl groups, and an organosilicon compound with hydrogen atoms, cured with a platinum group metal hydrosilylation catalyst, which provides a cured product with high refractive index, transparency, and temperature cycling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a linear organopolysiloxane having an aryl group is used to achieve high refractive index and transparency, then the refractive index and transparency are improved, but the temperature cycling resistance deteriorates
Solution Approach 1:
The invention uses a composite organopolysiloxane composition combining linear organopolysiloxane (for transparency and refractive index) with branched organopolysiloxane containing specific siloxane units (for temperature cycling resistance). This composite approach allows both requirements to be satisfied simultaneously by leveraging the complementary strengths of different polysiloxane structures.
Solution Approach 2:
The invention changes the structural parameters of the organopolysiloxane by controlling the ratio of different siloxane units (DS, TD, TR, T4) and the content of aryl groups. Specifically, maintaining DS/TD+TR+T4 within 0.3-2.0 and TD+TR within 10-80 mole% optimizes both optical properties and temperature cycling resistance.
2Strength
If a branched organopolysiloxane having RSiO3/2 units is used to achieve higher hardness, then the hardness is improved, but the temperature cycling resistance and crack resistance deteriorate
Solution Approach 1:
The invention applies local quality by specifying that the branched organopolysiloxane should contain R2SiO units (which provide hardness) while strictly excluding RSiO3/2 units (which cause brittleness). This selective incorporation of specific structural units allows hardness improvement without sacrificing temperature cycling resistance.
Solution Approach 2:
The invention changes the structural composition parameters by controlling the ratios of different siloxane units. The constraint that RSiO3/2 units shall not be present, combined with specific ranges for R2SiO and other units, optimizes the balance between hardness and flexibility for temperature cycling resistance.
3Ease of manufacture
If conventional organopolysiloxane compositions are used, then the composition is easy to manufacture, but the cured product exhibits peeling from substrate and crack generation
Solution Approach 1:
The invention employs a composite organopolysiloxane system combining linear and branched polysiloxanes with specific siloxane unit compositions. This composite structure provides both ease of manufacture (through conventional mixing and curing processes) and improved reliability (through the synergistic effects of different polysiloxane structures that prevent peeling and cracking).
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 enhanced refractive index, transparency, and temperature cycling resistance, making it suitable for optical device encapsulation, effectively addressing the limitations of conventional compositions.
Implementation Method 1
An addition-curable silicone composition includes an organopolysiloxane containing an aliphatic unsaturated group such as an alkenyl group to provide a cured product by being cured by a hydrosilylation reaction
Data Source
AI summary
An addition-curable silicone composition includes: a three-dimensional network organopolysiloxane having at least one alkenyl group and at least one aryl group in one molecule, having a siloxane unit represented by the following general formula, R2SiO, and SiO2, and not having a unit represented by RSiO3/2, wherein R represents an organic group; a linear organopolysiloxane having at least two alkenyl groups and at least one aryl group in one molecule; an organosilicon compound having at least two hydrogen atoms bonded to silicon atoms per one molecule, and not having an alkenyl group; and a hydrosilylation catalyst containing a platinum group metal. Thereby, there can be provided an addition-curable silicone composition which provides a cured product having high refractive index, transparency, and temperature cycling resistance, an optical device encapsulating material, and an optical device which is encapsulated with the optical device encapsulating material.