Silicone Primer Adhesion to Pre-Cured Substrates
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Solution Overview
Problem
The adhesion between adjacent interfaces of neighboring silicone elastomer sections in subsea insulation applications is often inadequate due to extreme temperatures and environmental conditions, despite the use of various primers, which typically rely on reactive chemistry processes that are sensitive to moisture and require catalysts.
Innovation Solution
A primer composition comprising a silicone polyether, a reinforcing filler, and a polydiorganosiloxane polymer with alkenyl or alkynyl groups, which is non-reactive and does not require catalysts, is applied to a pre-cured silicone elastomer substrate to enhance adhesion, allowing for immediate application of a hydrosilylation curable silicone rubber composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional primers relying on reactive chemistry processes are used, then adhesion between silicone elastomer layers is improved, but the process becomes sensitive to moisture and requires catalysts
Solution Approach 1:
The patent changes the chemical parameters of the primer composition by using silane-modified polyether polymers with specific molecular weights and silane content (0.5-10 mmol/g), replacing conventional reactive chemistry-based primers. This modification allows the primer to achieve strong adhesion through physical bonding and silane grafting without requiring catalysts or being sensitive to moisture conditions.
Solution Approach 2:
The patent creates a composite primer system combining polyether polymers with grafted silane groups. This composite structure provides both the adhesion properties of polyethers and the bonding capabilities of silanes, achieving strong interfacial adhesion between silicone elastomer layers without the drawbacks of conventional reactive primers.
2Temperature
If sequential molding process is used for subsea insulation, then thermal insulation performance is improved, but multiple joint sections create adhesion problems at interfaces
Solution Approach 1:
The patent applies the silane-modified polyether primer to the surface of pre-cured silicone elastomer sections before applying the next layer. This preliminary action ensures that the interface is pre-treated with adhesion-promoting groups, guaranteeing strong bonding at the joint sections where multiple insulation layers meet, thus solving the adhesion problem at interfaces while maintaining thermal insulation performance.
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 primer composition significantly improves the adhesion between silicone elastomer layers, as demonstrated by increased peel force in 180° peel tests, without the need for reactive chemistry or catalysts, ensuring strong bonds in challenging environmental conditions.
Implementation Method 1
silane-modified polyether polymers which have an average molecular weight of 2,000 to 5,000,000 and silane grafts with a silane content of 0.5 to 10 mmol/g
Data Source
AI summary
There is described a primer composition comprising a silicone polyether, a reinforcing filler, one or more polydiorganosiloxane polymer(s) and a carrier and the preparation and use thereof. The primer composition is particularly designed for use with silicone elastomers especially for addition (hydrosilylation) curing silicone elastomers, the preparation thereof, and to a process for improving the adhesion of silicone elastomeric compositions to pre-cured silicone elastomer material substrates. A method for improving the adhesion of silicone elastomer to a pre-cured silicone elastomeric substrate is provided. The method comprises: applying a primer composition to a silicone elastomer substrate; optionally, air-drying (or baking) the primer composition to form a uniform primer film covering the substrate; applying a hydrosilylation curable silicone rubber composition to the substrate covered with the primer to obtain a composite; and curing the composite in order to obtain a silicone elastomer adhesively bonded to a silicone elastomer substrate.