Orasa Patarapaiboolchai and Somjai Chaiyaphate

pp. 299 - 305

Abstract

The present invention provides a process for treating natural rubber to increase its flame retardant capability. The
process comprises a mixture of a natural rubber with, (a) halogenated free flame retardant agent (zinc hydroxystannate;
STORFLAM ZHS) and (b) halogenated flame retardant agent (decabromodiphenyl; Great Lake DE-83R and chlorinated
paraffins; Plastoil 152) and another material like antimony trioxide and aluminium hydroxide in appropriate amount, with ratio
of halogenated flame retardant agent: antimony trioxide 3:1. In the resulting product with halogen flame retardant showed
a more efficient flame retardant property than halogen free flame retardant, i.e. brominated flame retardant provide higher
efficiency than chlorinated and ZHS, respectively. The minimum requirement ratio for being flame retardant of antimony
trioxide: brominated or chlorinated agent is 7:21 or 10:30 phr while aluminium hydroxide: ZHS is 10: 150 phr. It was found that
burning rate was zero for brominated and chlorinated agent used but not for zinc hydroxyl stannate system. Average time of
burning (ATB) was 135, 118 and 41 second for brominated, chlorinated and ZHS flame retardant, respectively. Average extent
of burning (AEB) was 24, 19 and 14 millimeters, respectively. An advantage of this invention is that chemicals (antimony
trioxide and either brominated or chlorinated agent) added to natural rubber have the effect of rendering the natural rubber
flame-resistant like synthetic rubbers, chloroprene.