I do not have ASTM E-84 class I specification. However, I can give you the list of materials used as flame retardant.

1. Aluminium trihydrate

2. Ammonoium Polyphosphate + Melamine + pentaerythritol

3. Low quantity of Molybdates, Iron oxides, copper oxides, Zinc borates

4. Chlorinated paraffin wax alone or with antimony trioxide or in combination with antimony trioxide and selected reagents in no. (3)

In (1), H2O molecules come out at burning temperature to cool and reduce burning rate.

In (2) phosphoric acid generates, which reacts with pentaerythritol to form ester and at still higher temperature form char which is in the form of foam. It protects the substrate from coming in contact with flame.

In (3) mostly crosslinking occurs on the surface and protects from free burning.

In (4) (a) HCl generated make cover over burning substrate and protects it from coming in contact with air.

In 4(b) Antimony trichloride/ oxychlorides are formed, which protects better than HCl as it is heavier and can give longer protection.

In 4(c) HCl generated reacts with metal salts to form metal halides, which carries out crosslinking and forms surface char.

Really Valuable

Rheology and mechanical strength of the product on high filler loading also to be taken into consideration while formulationg FR products. It is very tricky approach than can give balance results in fire spread and smoke control for ASTM E 84. Class 1 rating : FS-25 , SD-450

To get the FR grade

Alumina trihydrate

Decabromodiphenyl ethane

antimony trioxide

kind of synergies can be used