Ceramic low smoke halogen-free fire-resistant polyolefin,as a new type of fireproof material,can form a hard ceramic protective layer at high temperatures and is widely used in the insulation and sheath layers of wires and cables.The extrusion processing temperature is a key parameter that affects material properties and production efficiency,and needs to be comprehensively controlled according to the material formula,equipment type,and process conditions.

 

　　From the existing process,the extrusion temperature of ceramicized low smoke halogen-free refractory polyolefin is usually controlled within the range of 110-160℃.For example,when a certain model of product is recommended to be processed using a regular polyolefin extruder,the temperature in the feed area should be set to 100℃,the body temperature should be distributed between 110-140℃,and the head temperature should be maintained between 120-145℃.The overall temperature gradient needs to be dynamically adjusted according to the plasticizing effect to avoid material decomposition and failure caused by exceeding 180℃.In addition,in some production cases,the temperature zones of the extruder are set more specifically:Zone I(feed section)125℃,Zone II 135℃,Zone III 145℃,Zone IV 155℃,and the head and mold temperature reaches 160℃.This staged heating design can ensure sufficient plasticization of materials and prevent performance degradation caused by local overheating.

 

　　

 

　　It is worth noting that the setting of extrusion temperature needs to be flexibly adjusted according to the characteristics of the equipment.For example,extruders with a length to diameter ratio(L/D)of 18-25 are more suitable for processing such materials.Reducing the screw compression ratio can improve the discharge efficiency,but it is necessary to synchronously control the solution temperature not to exceed 180℃.At the same time,using extrusion instead of semi extrusion tube extrusion can optimize surface smoothness and structural density,and the head temperature can be appropriately increased to around 145℃.In practical operation,factors such as workshop environment temperature,material dryness,and color masterbatch addition need to be considered.It is allowed to fine tune the set temperature by±5℃to ensure the smoothness and mechanical properties of the extruded cable.

 

　　

 

　　In addition,there are differences in temperature sensitivity among different formulations of ceramicized polyolefins.For example,composite materials containing kaolin or muscovite may require higher melting temperatures to achieve uniform dispersion,while systems with added silane coupling agents require strict control of the residence time at high temperatures to avoid coupling agent failure.Therefore,before production,it is necessary to determine the optimal process window through small-scale trials,taking into account both processing efficiency and finished product flame retardancy and ceramic performance.For example,a patented formula was mixed at 135℃and extruded at 180℃to successfully prepare an oxygen barrier layer with a fire rating of B under steam pressure of 1.1-1.2MPa.