1. Human factors
The amount of flame retardant added in the extruded board is very small, generally less than 10%. For the flame retardant to be evenly distributed in the material, stirring is the most critical part. It evenly contains about 5 grams of flame retardant, which requires a lot of manual stirring or a special mixer for stirring. Most manufacturers directly spray the flame retardant on the surface of the material and directly feed it into the feeder, although the feeder comes with its own stirring In a short time, only a small area of dispersion can be formed and squeezed out.
Second, equipment factors
Different equipment manufacturers have different design processes for the clearance, advancement rate, and plasticized dispersing screw of the screw barrel, which results in the plasticization, dispersion and residence time of the materials inside the screw barrel.
3. Flame retardant factors
The domestically produced flame retardants mainly include powders and granules. Due to the difference in density and PS particles, powder flame retardants can only adsorb a small part by frictional static electricity during the stirring process, and most of them will precipitate to the stirring along the gap between the particles The bottom of the device causes uneven dispersion of the flame retardant. The powder adsorbed on the surface of the particles will first come into contact with the screw barrel, which encounters high temperature and is severely decomposed. The free bromine in the decomposition process reacts with the screw barrel to generate iron bromide, which is extremely corrosive to the equipment, so it is not recommended use.