Can Halogen - free Flame - Retardant Materials Be Chosen for Making Polypropylene Flame - Retardant Sheets

The production process of general plastic PP sheets includes: feeding the materials; extrusion, using a single-screw extruder to extrude the material cylinder; heating in four zones; evaporating the moisture contained in the PP raw materials and promptly exhausting it through the exhaust holes set on the material cylinder; and extruding it into a mold for molding and shaping it into a sheet. 

For the halogen-free formula, among the halogen-free additive-type flame retardants used for flame-retardant PP, intumescent flame retardants are commonly seen. When each component in the intumescent flame retardant is used alone, its flame-retardant performance for PP is not good. However, when they are used together, the flame retardancy of PP is significantly improved due to the increased char formation rate. And the addition amount of the halogen-free flame-retardant system is generally relatively high. On the one hand, it is not convenient for a single screw to disperse the materials. On the other hand, too much addition amount will also affect other properties of the sheet. 

In order to obtain better dispersibility and a better flame-retardant effect, it is still recommended to use the special flame-retardant master batch for PP sheets!