Multilayer Silicone Adhesion via SiH-Alkenyl Ratio Control
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Solution Overview
Problem
Current methods for manufacturing multilayer silicone structures face challenges in achieving excellent layer-to-layer adhesion, particularly in photovoltaic modules, where cohesive failure occurs, and there is a need for materials that provide resistance to climate conditions and adherence to various substrates such as glass, plastic, and metal.
Innovation Solution
A process involving two curable silicone compositions, where the first composition is applied to a substrate and then a second composition is cured onto the first, using specific polyorganosiloxanes with SiH and alkenyl groups, along with metal catalysts and oxidic fillers, to achieve strong adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two layer encapsulation process is applied to build modules with defined front and back layer upon semiconductors, then complete encapsulation is achieved, but cohesive failure occurs at the interface between layers
Solution Approach 1:
The patent resolves the cohesive failure issue by changing the chemical composition parameters of the two silicone layers. The first layer uses a silicone composition with a molar ratio of SiH groups to alkenyl groups of 0.5-2.0, optimized for substrate bonding. The second layer uses a composition with a molar ratio of 2.0-4.0, optimized for layer-to-layer bonding. This parameter differentiation ensures strong interface strength while maintaining complete encapsulation reliability.
2Reliability
If silicone encapsulants are used instead of EVA for encapsulating photovoltaic cells, then resistance to UV radiation and extreme temperature changes is improved, but layer-to-layer adhesion deteriorates
Solution Approach 1:
The patent maintains the climate resistance benefits of silicone encapsulants while resolving the adhesion issue through parameter changes in the silicone composition. By optimizing the molar ratio of SiH groups to alkenyl groups differently in the two layers (0.5-2.0 for the first layer, 2.0-4.0 for the second layer), the patent achieves both UV radiation stability and extreme temperature resistance along with excellent layer-to-layer adhesion.
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 process ensures excellent adhesion between silicone layers, providing a robust and durable multilayer structure that withstands climate conditions and adheres well to various substrates, enhancing the longevity and performance of electronic devices like solar cell modules.
Implementation Method 1
a system of addition (or light, in particular, UV light) curable silicone compositions comprising at least of two silicone compositions whereby a second composition 2) is applied and cured onto a first composition 1)
Implementation Method 2
along with metal catalysts and oxidic fillers, to achieve strong adhesion and durability
Data Source
AI summary
The present invention is directed to a process for the manufacture of a multilayer silicone structure of cured silicone elastomer layers wherein the compositions of each of the curable silicone elastomers are chosen such as to provide excellent layer-to-layer adhesion of the said cured silicone elastomer layers, that is, the layers do not suffer form cohesive failure. The multilayer silicone structures may be used for example for the manufacture of electronic devices, coatings, shaped molded articles, laminates etc.