Discussion on Processing Precautions of Halogen-free Flame Retardant Wire And Cable Materials

Wire and cable material to achieve the requirements of low smoke without halogen flame retardant, must add a lot of inorganic flame retardant, extrusion, melt viscosity, the fluidity is poor, easy to produce friction heat, lead to melt local temperature is too high, the material in the fuselage long time decomposition, decomposition of gas easy to form pores in products. Low smoke halogen-free flame retardant wire and cable material extrusion processing, we should pay attention to the following points.

(1) Selection of the extruder. Due to the more additives of low smoke halogen-free flame retardant wire and cable material and the large melt viscosity, the extruder with relatively low screw compression should be used. Ordinary single screw extruder has low shear rate and poor mixing capacity; the double screw extruder has high mixing capacity, but processing high filling low smoke halogen flame retardant wire and cable material, often caused by material decomposition, discoloration and other problems, so it is best to choose double order mixing extruder combined with single screw and double screw. According to the reciprocating single screw mixer is an ideal low smoke halogen free flame retardant wire and cable material processing equipment.

(2) Selection of processing technology. In addition to the selection of the appropriate extruder, the processing technology should also be reasonable. If the temperature is too high, the additives will decompose, resulting in pores; too low temperature will produce poor plasticizing. The fuselage pressure should be reduced as far as possible, and the screw speed should not be too high under the condition of ensuring sufficient plasticization of materials, the extrusion temperature should be reduced appropriately. The processing process should be adjusted according to different materials and different formulations.

(3) Before material extrusion processing, drying should be done to avoid the product section pores.

(4) Due to the poor fluidity of the material and the friction resistance with the equipment is large, organic silicon can be added to improve the dispersion of inorganic flame retardant and reduce the processing torque. The addition of organic silicon can improve the flame retardant performance of wire and cable material, is a good processing additives.

In short, low smoke halogen-free flame retardant wire and cable material for processing equipment and process conditions and other aspects of the requirements, must be strict according to the appropriate extrusion equipment and process conditions according to the raw material characteristics, product performance and extrusion characteristics.