The Research Of Preparation And Properties Of Effectively Intumescent Flame Retardant Polypropylene Materials

Polypropylene(PP) is a sort of commodity thermoplastic resins, It is widely used in every respect of people's life and production because it has fine general performance, but the further application is restricted for its flammability. The intumescent flame retardant (IFR) have some advantages, such as lower smoke, no toxic, no corrosive gases and so on. So the new IFR systems have been worked out continuously and used as the flame retardant in polypropylene. The research and application of IFR systems have been paid a great attention.In this paper, a new IFR system mainly consisted of a triazine polymer which was design and synthesis in our laboratory, named as a charing-foaming agent (CFA), ammonium polyphosphate (APP) and other additive. Some important factors affecting the flame retardancy were studied, such as the ratio of APP to CFA, type and amount of the synergistic agents such as zeolites, rare earth oxides, the amount of anti-dripping agent and so on. The experimental results demonstrated that the flame retardancy was the best when the weight ratio of APP/CFA is 4/1, and 4A, 5A, H-Beta zeolites, the rare earth oxides, SiO₂, TiO₂ etc all have good synergistic effects, those substance all could enhance the LOI value to 33～35 and help the UL-94 rating test (1.6mm) from no rating to V0 rating at the IFR loading of 20wt%, and those substance all have a optimal content is 5% in IFR. The anti-dripping agent could resolve the flaming dripping phenomenon of the flame ratardant PP materials which have big Melt Flow Rate, and help the UL-94 rating test (1.6mm) from low rating to V0 rating.TGA, CONE and SEM were used to evaluate the thermal degradation, combustion and the morphological structures of the burnt char layer of PP-IFR materials respectively. The results show that the flame retardant PP have extraordinary lower fatalness in the fire compared with pure PP resin. The synergists could efficiently reduce the heat and smoke release rate and total amount, especially for the smoke production rate and total smoke production. The research also found that the synergists could accelerate the degradation of the systems, enhance the char formation in high temperature to form stabile, compact char layer, and prevent the char layer from cracking, thereby a better flame retardancy is obtained.In this paper, we also studied the flame retardancy and properties of different type of PP-IFR materials. It was found that the IFR are quite effective in many types of PP resins. The IFR-PP materials with 20wt% IFR could pass the UL-94 rating test (1.6mm), some of types (K9020)could pass the test at 18wt% content of IFR in PP. The LOI value of all type of PP flame retardant PP-IFR materials could be higher than 30 at 20wt% IFR loading, and 35 at 26wt% IFR. However, there have some influence on the mechanical property of the PP-IFR materials, especially for the Izod Impact Strength of polypropylene(copolymer).