Fluorosilicone Composition Defoaming via Viscosity Control
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Solution Overview
Problem
Fluorosilicone polymers exhibit poor defoamability, leading to difficulties in removing bubbles from curable compositions, especially in one-part systems used for potting electronic parts, where vacuum deaeration is inefficient.
Innovation Solution
A liquid curable fluorosilicone composition comprising specific organopolysiloxane, organohydrogenpolysiloxane, an addition catalyst, and diorganopolysiloxane components, along with fine powder silica reinforcement, which enhances defoamability and maintains resistance to gasoline and chemicals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fluorosilicone compositions are used, then gasoline resistance and chemical resistance are maintained, but defoamability is extremely poor
Solution Approach 1:
The patent modifies the chemical composition parameters of the fluorosilicone system by introducing specific organopolysiloxane compounds with controlled molecular structures and ratios. This changes the physical-chemical parameters of the composition to enable bubble nucleation and collapse while maintaining the fluorosilicone's inherent chemical resistance properties.
Solution Approach 2:
The patent creates a composite fluorosilicone composition by combining multiple components: base fluorosilicone polymer, specific organopolysiloxane additives, catalysts, and fillers. This composite approach allows the material to simultaneously achieve defoamability through the synergistic interaction of components while preserving gasoline and chemical resistance from the fluorosilicone backbone.
2Productivity
If vacuum deaeration is used to remove bubbles, then bubble removal is achieved in two-part systems, but the process is complex and time-consuming
Solution Approach 1:
The patent enables the fluorosilicone composition to remove its own bubbles through internally generated defoaming mechanisms. The composition contains built-in defoaming agents and controlled viscosity characteristics that allow bubbles to collapse automatically during mixing and curing, eliminating the need for external vacuum deaeration equipment.
Solution Approach 2:
The patent extracts and eliminates the need for complex vacuum deaeration equipment by incorporating defoaming functionality directly into the composition chemistry. The harmful bubbles are removed through chemical mechanisms within the material itself rather than through external mechanical intervention.
3Ease of operation
If one-part curable fluorosilicone composition is used, then mixing steps are eliminated, but bubbles remain in the potting layer
Solution Approach 1:
The patent adjusts the viscosity, surface tension, and chemical composition parameters of the one-part fluorosilicone system to enable spontaneous bubble collapse. By controlling the molecular weight distribution and adding specific organopolysiloxane compounds, the composition maintains ease of application while achieving reliable bubble removal without additional mixing steps.
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 significantly improved defoamability, allowing for efficient bubble removal and maintaining chemical resistance, resulting in a cured product with enhanced tear resistance and reduced rejection rates during molding.
Implementation Method 1
a liquid curable fluorosilicone composition comprising a specific organopolysiloxane, an organohydrogenpolysiloxane, and an addition catalyst
Data Source
AI summary
A liquid curable fluorosilicone composition having improved defoamability is provided. The composition comprises (A) an organopolysiloxane having a viscosity at 25°C of 100 to 500,000 mPa·s and represented by the following formula: (CF3CH2CH2)aRbSiO(4-a-b)/2 wherein R is a monovalent hydrocarbon group with the proviso that at least 0.001% by mole of the hydrocarbon group is an alkenyl group, a is 0.1 to 1.0, b is 2.5 to 1.0, and a+b is 1.8 to 3.0, (B) an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to the silicon atom in a molecule, (C) an addition catalyst, and (D) a diorganopolysiloxane having a viscosity at 25°C of 1 to 10,000 mpa·s which does not comprise trifluoropropyl group but comprises dimethylsiloxane unit.