Some Knowledge about flame-retardant silicone rubber

When it comes to flame-retardant silicone, let's first distinguish a few concepts to understand what flame-retardant is:

1. Flammability: The ability of materials or products to undergo flame combustion under specified experimental conditions;

2. Non flammability: The ability of a material to undergo flameless combustion under specified experimental conditions;

3. Flame retardancy: The characteristics of materials that slow down, terminate, or prevent flame burning;

4. Flame retardant materials: Compared with ordinary materials, materials that are difficult to ignite, easy to extinguish after ignition, or difficult to spread under fire conditions, have low heat release, low smoke release, and other flame retardant properties. What flame retardants can help silicone achieve flame retardant properties;

5. Flame retardancy level: UL94 is a plastic flammability standard issued by Underwriters Laboratories in the United States, which classifies plastics based on their burning behavior for different thicknesses. Flame retardant silicone is usually classified into three grades: UL94-V0, UL94-V1, and UL94-V2

What additives are usually used to enhance the flame retardancy of silicone? Flame retardant silicone rubber can be prepared by using alumina hydrate, calcium carbonate, carbon black, and platinum compounds as flame retardants. The average particle size of alumina hydrate should be below 50um, and the average particle size of calcium carbonate should be below 20um. Carbon black can be acetylene carbon black, hot cracking carbon black, or furnace process carbon black, with a specific surface area greater than 10 ㎡/g and a particle size of 0.05-0.2um; Platinum compounds can be selected as platinum/alcohol complexes or platinum/vinyl siloxane complexes.

Flame retardant silicone not only has excellent mechanical properties unique to silicone rubber itself, but also has good electrical insulation and flame retardancy. It is increasingly widely used in our daily lives, such as in the electronic and electricity industry (wires, silicone cable and sheaths), automotive, aerospace, high-speed rail, and other products and components with flame retardant application scenarios.

However, according to the definition of flame retardant materials, we must note that this type of material is not non combustible, but difficult to burn. So we can make it clear that flame retardant silicone rubber cannot absolutely prevent the occurrence of fires. Flame retardant silicone can only prevent small fire sources from spreading and developing into fires, and can delay the spread and development of large-scale fires that have already occurred, buying time for firefighting. In this sense, flame-retardant silicone is not omnipotent, but it has prevented 90% of small fires from developing into large-scale fires and countless losses of life and property. Therefore, flame-retardant silicone rubber is essential