Flame retardant, smoke suppressing additives for PVC etc. - comprising solid solns. of zinc oxide and calcium oxide or magnesium oxide and having no adverse effect on heat stability

摘要

Flame retardant, smoke suppressing additives for plastics materials comprises a solid soln. of ZnO and CaO and/or MgO. The solid soln. pref. contains ZnO and CaO in a wt. ratio of 50:50 - 85:15. or ZnO and MgO in a wt. ratio of 30:70-50:50. The solid soln. pref. has a specific surface of >10 m2/g., esp. >16 m2/g. The solid soln. additives give excellent flame retardant and smoke suppressing properties, e.g., to PVC without adversely affecting the thermal stability of the polymer. Milled ZnO is mixed with milled MgO and/or CaO in the desired ratio and the mixt. calcined at >=500 degrees C, pref. 800-1000 degrees C and is not >1500 degrees C.