Fire resistance Imerys talcs and micas act in synergy with flame retardant fillers and additives in EVA systems
Acting in synergy with flame retardant fillers and additives, Imerys minerals create a physical barrier to fire, reducing combustion rate, improving char strength and decreasing smoke quantity and rate of emission.
Imerys talc creates a mass transfer barrier restricting the transfer of combustible materials and oxygen and imparting a cohesive foam structure to the polymer.
It is particularly effective partial replacement of magnesium hydroxide (MDH) and aluminum tri-hydrates (ATH) reducing compound costs without affecting fire retardant properties.
- Limits burnable gas emissions and oxygen diffusion by foaming effect, resulting in delayed combustion
- Creates a physical barrier effect limiting heat and mass transfer
- Is an excellent char promoter
- Improves ash cohesion
- Generates less smoke
- Is a natural, environmentally friendly solution
Effect of talc in EVA systems
High aspect ratio talcs
For more stringent requirements, Imerys High Aspect Ratio Mistron HAR® talc provides an outstanding intumescent effect which retards fire ignition and protects the EVA from combustion. This intumescence is mainly due to the conjunction of heterogeneous bubble nucleation, barrier effect, increased viscosity and char promotion.
Mica can also partially replace ammonium polyphosphate (APP) systems in polyolefins, while improving mechanical properties without affecting overall fire resistance.
Loading levels of around 30% APP are commonly used to meet UL94 requirements such as V-0 ratings; however APP is expensive and diminishes physical properties such as tensile strength. Replacing up to one third of APP flame retardant by Imerys mica not only improves fire resistance, char promotion and afterglow time, it boosts the mechanical properties of the material.
We recommend our Suzorite® range for this application.
HAR® talc for fire resistant cables
We offer a full range of bespoke formulation and technical and process support services to help you match the right mineral grade to your application requirement.