Silicone Rubber Composition Shape Retention After Burning
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Solution Overview
Problem
Conventional silicone rubber-based refractory products lose their shape and functionality when exposed to high temperatures, and existing solutions with platinum-based compounds crack and allow fire to spread, while being difficult to knead due to heavy filler loads.
Innovation Solution
A silicone rubber composition combining an organopolysiloxane with silicon-bonded alkenyl groups, reinforcing silica, and calcined mica, along with a curing agent, which provides excellent roll processability and shape retention after burning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional silicone rubber is used for refractory building material, then heat resistance and weather resistance are improved, but the material burns down to ash and loses its original shape when exposed to high temperatures for long periods
Solution Approach 1:
The patent combines organopolysiloxane with specific molecular structure (containing silicon-bonded hydroxyl groups and hydrolyzable groups) with zinc oxide, aluminum hydroxide, and other inorganic fillers to create a composite material that forms a ceramic-like structure after burning, thereby retaining shape while maintaining heat resistance
2Temperature
If platinum-based compounds are added as refractory aid to improve fire resistance, then heat resistance is enhanced, but the product cracks and allows fire to spread in high-level fire tests, and becomes brittle and spalling under external stresses
Solution Approach 1:
The patent changes the chemical composition parameters by using organopolysiloxane with specific functional groups (silicon-bonded hydroxyl groups and hydrolyzable groups) that react to form a more stable ceramic structure, and adjusts the types and proportions of inorganic fillers to achieve both fire resistance and mechanical strength without the brittleness problems of platinum-based compounds
3Temperature
If zinc oxide, aluminum hydroxide, and other inorganic fillers are added to improve fire resistance, then sinterability is enhanced, but the composition becomes heavily loaded with fillers and is sticky to rolls and very difficult to knead
Solution Approach 1:
The patent applies local quality by using organopolysiloxane with specific functional groups that provide reactive sites for filler interaction, creating localized bonding regions that improve filler distribution and reduce stickiness, while the specific molecular structure allows for better processing characteristics despite high filler content
4Reliability
If conventional silicone rubber composition is used, then basic gasket function is provided, but the material is sticky to rolls and very difficult to knead when heavily loaded with fillers for fire resistance
Solution Approach 1:
The patent changes the molecular structure parameters of the base polymer by using organopolysiloxane with specific functional groups and molecular weight ranges, which modifies the rheological properties and reduces stickiness during processing, enabling easier kneading while maintaining the essential gasket functionality
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 exhibits improved sinterability and roll workability, making it suitable for refractory materials like gaskets with enhanced fire resistance and mechanical strength.
Implementation Method 1
can retain the original molded shape even after prolonged exposure to fire because the ash of the burned article sinters (into a ceramic mass)
Data Source
Figure 1
AI summary
The present invention relates to a silicone rubber composition comprising: (A) 100 parts by mass of an organopolysiloxane that has a degree of polymerization of 100 or more and contains at least two alkenyl groups each bound to a silicon atom in the molecule; (B) 10 to 100 parts by mass of a reinforcing silica having a specific surface area (BET method) of 50 m2/g or more; (C) 1 to 100 parts by mass of calcined mica having an average particle diameter of 20 µm or less; and (D) an effective amount of a curing agent. According to the present invention, even when a silicone rubber molded article is exposed to flame for a long time, ash of the silicone rubber molded article after firing is sintered (is transformed into a ceramic material) and the shape of the silicone rubber molded article before the firing (sintering) can be maintained. In addition, the rolling properties (workability) in a kneading step in the production of the silicone rubber composition is excellent.