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Fire resistance

Fire resistance Imerys minerals - cost-effective fire retardants and insulation additives

Imerys talc, mica, and wollastonite are successfully used in many halogenated, halogen-free, and intumescent flame retardant (FR) formulations as FR synergists and/or for improving mechanical, thermal, rheological and aesthetic properties of fire resistant plastics.

Imerys minerals in intumescent flame retardant PA 6

Imerys talc, mica and wollastonite products demonstrate synergistic flame retardant (FR) performance allowing manufacturers to reduce FR additive loading or FR specimen thickness when used for partial replacement of chopped glass fiber (GF) in polyamide 6. 

Replacing 10% of glass fiber with any of the above minerals improves rheology of 30% GF-filled FR PA which is a known weakness of glass fiber reinforced PA6.

For example, partial replacement of GF with high aspect ratio talc or mica allows compounders to achieve UL94 V0 or V1 rating at decreased loading levels of organic phosphinate-based intumescent FR additives in a 30% GF-filled PA6 formulation at 1/8” or 1/16” specimen thickness.

We recommend our HAR® talc, Suzorite® mica, and the surface treated Nyglos® wollastonite line of products for GF replacement in intumescent FR formulations of PA6.

Talc for MDH and ATH replacement

Imerys talc can be used effectively for partial replacement of magnesium hydroxide (MDH) and aluminum tri-hydrates (ATH) to reduce compound costs without affecting flame retardant properties. Talc creates a mass transfer barrier and imparts a cohesive foam structure to the polymer.

Imerys talcs:

  • Reduce the combustible content of the compound
  • Reduce combustion rate
  • Contribute to char formation

We recommend:

  • Luzenac 10M2 grades for ATH replacement for color and non-color sensitive applications
  • Mistron® R10 talc for MDH replacement
  • HAR® high aspect ratio talcs for high fire resistant thermoplastics. High aspect ratio talcs provide outstanding intumescent effect which retards fire ignition.

Talc for flame retardancy in polypropylene (PP)

Used in combination with magnesium hydroxide (MDH) in PP quenching and intumescent systems, Imerys talcs improve flame retardancy (FR) of PP compounds used for E&E components such as computer and electronic device housings, while reducing the overall formulation cost.

Imerys talcs:

  • limit gas emission and oxygen diffusion resulting in delayed combustion
  • create a physical barrier effect limiting heat and mass transfer
  • reduce dripping in intumescent systems
  • improve thermal stability
  • promote char formation
  • improve ash cohesion
  • reduce smoke and afterglow

We recommend Luzenac 1445 for PP quenching and intumescent systems.

Mica for APP replacement

Imerys mica grades make cost-effective replacements for ammonium polyphosphate (APP) commonly used to meet UL94 V0 requirements in halogen-free flame retardant formulations for polyolefins.

APP is not only expensive it also diminishes physical properties such as tensile strength.

Imerys micas can be used as a synergist to replace up to one third of APP flame retardants where they:

  • Boost flexural modulus
  • Improve HDT
  • Reduce shrinkage and warping
  • Promote char formation

We recommend our Suzorite® range for APP replacement in polyolefins.

UL94 ratings at 1/8” specimen thickness

UL94 ratings for 1/8” specimen

UL94 ratings at 1/32” specimen thickness

UL94 ratings for 1/32” specimen

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.

Please contact us, we will be only too happy to help

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