Light-Diffusing Organopolysiloxane Composition for Crack-Resistant Optics
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Solution Overview
Problem
Existing light diffusing materials lack an optimal balance between light transmittance, light diffusion properties, and mechanical durability, particularly in reflow soldering steps, and there is a need for improved light extraction efficiency from light emitting devices like LEDs.
Innovation Solution
A curable organopolysiloxane composition comprising organopolysiloxanes with at least 10 mol% aryl groups, inorganic fillers, and specific organosilicon compounds, which form a cured product with enhanced light transmittance, diffusion, and mechanical properties, suitable for optical members and light emitting diode sealing agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional silicone resin compositions are used for light diffusing materials, then light transmittance and light diffusion properties can be achieved, but mechanical durability and resistance to cracking in reflow soldering steps deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating aromatic rings (phenyl groups) into the polysiloxane backbone structure and controlling the molar ratio of aromatic to aliphatic groups. This structural modification increases the glass transition temperature and crosslinking density, thereby improving mechanical durability and heat resistance while maintaining optical properties
Solution Approach 2:
The patent creates a composite material system combining organopolysiloxane with specific aromatic content, inorganic fillers (such as silica particles), and crosslinking agents. This composite structure provides both the optical transparency needed for light transmission and the mechanical strength required for reflow soldering durability
2Illumination intensity
If inorganic fillers are added to improve light diffusion properties, then light extraction efficiency increases, but mechanical strength and toughness deteriorate
Solution Approach 1:
The patent utilizes inorganic filler particles (such as silica) with controlled size distribution (0.1-10 μm) dispersed within the polysiloxane matrix. These particles create a porous-like scattering structure that diffuses light effectively while the controlled concentration (20-80 wt%) and surface treatment maintain matrix continuity and mechanical integrity
Solution Approach 2:
The patent applies local quality by using surface-treated inorganic fillers with specific surface chemistry that enhances interfacial adhesion to the polysiloxane matrix. This localized improvement at the filler-matrix interface prevents stress concentration and maintains overall mechanical strength despite the presence of dispersed particles
3Illumination intensity
If thick optical members are formed to improve light extraction efficiency, then light diffusion performance increases, but cracking and mechanical failure increase
Solution Approach 1:
The patent modifies the polymer chain structure by incorporating aromatic rings that increase chain rigidity and intermolecular interactions. This structural change raises the glass transition temperature and improves the material's ability to withstand thermal stress during reflow soldering, preventing cracking in thick sections
Solution Approach 2:
The patent employs crosslinking agents as intermediaries that form a three-dimensional network structure within the polysiloxane matrix. This crosslinked network acts as a reinforcing framework that distributes stress uniformly throughout thick optical members, preventing crack propagation while maintaining optical clarity
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 tough, durable cured product with improved breaking elongation, reducing cracking and maintaining mechanical strength, suitable for thick optical members and light diffusion films.
Implementation Method 1
a hydrolyzable silyl group... capable of reacting with the reactive group contained in the organopolysiloxane
Implementation Method 2
one or more inorganic fillers; and one or compounds selected from an organosilicon compound (which has a functional group (capable of reacting with the reactive group contained in the organopolysiloxane))
Data Source
AI summary
Provided herein is a light diffusing material having excellent light transmittance, light diffusion properties, and mechanical properties. The light diffusing material comprises a curable organopolysiloxane composition, comprising: A) an organopolysiloxane having reactive groups; B) one or more inorganic fillers; and C) an organosilicon compound different from component A), and comprising component(s) C1) and/or C2). Component C1) is an organosilicon compound having a reactive functional group that can bond with component A), a hydrolyzable silyl group and/or a silicon atom-bonded hydroxyl group, and two or more silicon atoms, in the molecule. Component C2) is an organosilicon compound having a reactive functional group with three or more carbon atoms, which can bond with component A), a hydrolyzable silyl group and/or a silicon atom-bonded hydroxyl group, and one or more silicon atoms, in the molecule. The mass of component B) is 30 to 95% relative to the mass of the overall composition.