Room Temperature Curable Silicone Bubble Removal via Humidity Control
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Solution Overview
Problem
Gas bubbles trapped in bulk-cured room temperature condensation curable silicone compositions lead to visual defects in applications like insulated glazing, where transparency is crucial, due to the slow migration of bubbles to the surface during the rapid bulk cure process, and traditional vacuum degassing methods can cause more issues like swelling and reduced cure speed.
Innovation Solution
A method involving applying a bulk cured silicone composition in a controlled atmosphere with a relative humidity of 0-40% to allow initial curing, followed by introducing a dry gaseous blanket to reduce humidity further, eliminating the need for vacuum systems and ensuring gas bubbles are removed without causing additional defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If bulk cure process is used to cure silicone composition quickly throughout the bulk material, then cure speed is improved, but gas bubbles become trapped in the material causing visual defects
Solution Approach 1:
The patent applies vacuum pressure before the bulk cure process to remove gas bubbles from the silicone composition. By performing this degassing action preliminarily, the composition is freed of bubbles before rapid curing occurs, preventing bubble entrapment and ensuring transparency while maintaining fast cure speeds.
Solution Approach 2:
The patent extracts gas bubbles from the silicone composition by applying vacuum pressure. This removal of harmful gas bubbles before curing prevents them from being trapped in the final cured material, thereby maintaining transparency and optical properties while allowing rapid bulk curing to proceed.
2Manufacturing precision
If traditional vacuum degassing methods are used to remove gas bubbles, then gas bubble removal is improved, but swelling and reduced cure speed occur
Solution Approach 1:
The patent modifies the vacuum application parameters by controlling the vacuum pressure level and duration specifically. By optimizing these parameters, the method achieves effective bubble removal without causing the harmful side effects of swelling and cure speed reduction that occur with traditional vacuum degassing methods.
Solution Approach 2:
The patent applies vacuum pressure for a controlled, limited duration and at specific pressure levels rather than prolonged or excessive vacuum application. This partial action approach is sufficient to remove bubbles while avoiding the adverse effects of over-vacuuming, such as swelling and disrupted cure kinetics.
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
Significantly reduces the presence of trapped gas bubbles in the cured silicone material, resulting in fully transparent and bubble-free elastomers, enhancing the optical properties and usability of molded products like spacers for insulated glazing.
Implementation Method 1
One-part room temperature condensation curable silicone compositions are provided with a view to generating skin or diffusion cured silicone-based materials
Implementation Method 2
the cure speed is dependent on the speed of diffusion of moisture from the sealant/encapsulant interface with air to the inside (i.e. the bulk or core)
Implementation Method 3
Gas bubbles may also be generated in pre-cured compositions by the release of dissolved gases under pressure/during storage or can be formed through chemical reactions which take place during the cure process resulting in the generation of volatile compounds
Data Source
AI summary
This disclosure relates to a method for reducing gas bubble entrapment from bulk cured room temperature condensation curable silicone compositions. The method comprising applying a predefined volume of a bulk cured room temperature condensation curable silicone composition bulk curable silicone composition onto or into a target substrate. The method further comprising at least initially curing the composition in an atmosphere having a relative humidity of X %, wherein X has a value in the range of 0<X≤40%, for a predetermined time or until no gas bubbles remain visible in the composition.