Study On The Preparing Process Of Microcapsulated Red Phosphorus Flame Retardant

With the development of technology, because of polymer materials’ highspecific strength, good toughness, wear-resisting, corrosion resistance, goodinsulation and many other excellent performance, it has been widely used inconstruction, automotive, aviation and many other fields gradually for its uniqueadvantages, they are closely related to all aspects of human life. However, polymermaterials are very easy to burn, which makes the fire accident easy to come out. Asan additive which can improve the anti-flammable of materials, the flame retardantcan improve the flame resistance of polymers significantly. Red phosphorus (RP) isan important kind of phosphorus flame retardant with high phosphorus content andflame retardant efficiency, but at the same time, its application is limited because ofsome disadvantages such as easy to dilute, dark red appearance, easy to release toxicgas such as PH3, etc. Therefore, red phosphorus is difficult to use as flame retardantin reality directly. Microencapsulation technology is anemergingtechnology,redphosphorus’s property can be improved through selecting a suitable capsule materialto coat its surface.The topic selected aluminum hydroxide and MQ silicone resin as capsulematerials, red phosphorus powder as the capsule core. The aluminum hydroxidemicroencapsulated red phosphorus and MQ silicone resinmicroencapsulated redphosphorus was preparedthrough the method chemical precipitation and in-situpolymerization, respectively. By designing a single factor experiment and orthogonalexperiment, the impact of each factor towards products’ thermal decompositiontemperaturetendency were investigated. Also, the favorable conditions of eachmethod were found. After that, the product which was prepared under favorableconditions’s hygroscopicity, particle morphology, antioxidant properties werecharacterized, the results were as follows:(1) The impact of each factors towards the products’ thermal decompositiontemperature in the preparing process of aluminum hydroxide microencapsulated red phosphorus in descending order were as follows: reaction temperature, the amount ofdispersant, stirring speed, reaction time, the value of pH, the ratio of capsule material.The analysis of variance reflected that the reaction temperatue, the amount ofdispersant and the stirring speed were highly significant factors(Pis less than0.01),the reaction time and the value of pH were significant factors(Pis less than0.05). Thefacorable conditions of the process were as follows: the value of pH was7.5, theamount of dispersant was0.6%, the stirring speed was300r/min, the reaction timewas1.0h, the reaction temperature was35℃, the ratio of capsule material was100%.Under this condition, the product’s thermal decomposition temperature was328.5℃.(2) The impact of each factors towards the products’ thermal decompositiontemperature in the preparing process ofMQ silicon resin microencapsulated redphosphorus in descending order were as follows: the value of M/Q, the amount ofHCl, the amount of water, the reaction temperature, the reaction time, the amount ofethanol. The analysis of variance reflected that the amount of HCl was highlysignificant factor(Pis less than0.01), the value of M/Q was significant factor(Pis lessthan0.05). The favorable conditions of the process were as follows: the value of M/Qwas0.6, the amount of water was8times the amount of MM and TEOS, the amountof ethanol was0.9%, the amount of HCl was1.0%, the reaction temperature was65℃, the reaction time was4.0h. Under this condition, the product’s thermaldecomposition temperature was257.6℃.(3) After the characterizing of metallurgical microscope at500times, the redphosphorus was completely coated by the capsule materials. The particle size analysisshowed thatthe particle size distribution of the products were homogeneousaftercoating. Compared with the uncoated, the properties of the red phosphorus such ashygroscopic, antioxidant, the release of PH3gas emissions, the variation of pH valuehave been greatly improved.The experiment shows that: the red phosphorus’s low thermal decompositiontemperature, easy to dilute, easy tooxidation, easy to release toxic gas such as PH3and many other disadvantages have been greatly improved while its efficiency is stillvery high after coating. It is quiet suitable for the red phosphorus flame retardant’stendency of high efficiency, low toxicity and halogen-free. In this way, the red phosphorus flame retardant’s scope of application has been greatly expanding and itmakes its application prospects broader and broader.