Preparation And Application Of Brucite Matrix Composite Flame Retardant

The consumption of inorganic magnesium hydroxide and aluminium hydroxide exceeds50%of total consumption of all flame retardant, and exists a rising trend year by year. Because of better fume suppression、higher thermal stability and more wide using range, magnesium hydroxide will be one of development directions of halogen-free flame retardant. Magnesium hydroxide contains naturals and synthetics. Brucite is synthetic magnesium hydroxide flame retardant. Natural brucite has more advantage than synthetic magnesium hydroxide because of its low cost. But it exits two problems:poor compatibility and huge addition level in polymers, coating a layer of organic flame retardant on brucite can effectively solve the above problem. Based on this consideration, we design to prepare a kind of composite flame retardant by compounding brucite and nitrogen-phosphorus intumescent flame retardant. In the previous investigations, the composite flame retardant prepared by brucite、polyphosphoric acid and long-chain amine can meet flame retardancy requirement but can not form continuous and dense carbon residue. Low nitrogen content of long-chain amine may be the reason. Based on the above, we design to use melamine which has high nitrogen content to substitute long-chain amine. The results are listed below:(1) The preparation of encapsulated brucite composite flame retardant based on melamine resin and its performance in POE. The encapsulated brucite flame retardant was prepared by coating polyphosphoric acid and melamine resin on brucite, industrial alcohol as reaction system. XRD、contact angle test、particle size distribution tes、TG、SEM and FT-IR confirm its structure. Adding encapsulated brucite composite flame retardant to POE through melting blending method, the influence on mechanical property and flame retardancy of POE was also investigated. The POE product filled with50%encapsulated brucite had the utmost limit oxygen of30, tensile strength of9.58MPa and elongation at break of430%that can accordance the demand of tensile strength greater than9.0MPa, elongation at break greater than150%in cable materials.(2) The preparation of MPP/brucite composite flame retardant and its performance in POE. Compared with the above encapsulated physical coated process, the salification reaction between melamine and polyphosphoric acid before compounding with brucite was investigated. MPP was prepared by melamine and polyphosphoric acid in DMF through only one step, and it was characterized by XRD、FT-IR and TG. MPP/brucite was prepared by compounding MPP and brucite directly. TG analysis indicates that MPP/brucite was benefit for the icreasing of carbon residue and its thermostability. Adding MPP/brucite composite flame retardant to POE through melting blending method, the influence on mechanical property and flame retardancy of POE was also investigated. The POE product filled with50%MPP/brucite composite flame retardant had the utmost limit oxygen of31, tensile strength of12.86MPa and elongation at break of369%that can accordance the demand of tensile strength greater than9.0MPa, elongation at break greater than150%in cable materials.