▎ 摘　　要

NOVELTY - Multi-layer composite pipe comprises inner layer, a middle layer close to the outside of inner layer, and an outer layer close to the outside of middle layer. The inner layer is a modified fluoroolefin polymer inner layer. The intermediate layer is an alloy granular intermediate layer. The intermediate layer of the alloy pellets contains a compatibilizer. The outer layer is a polyolefin outer layer. USE - Multi-layer composite pipe with high thermal conductivity and high heat resistance. ADVANTAGE - The multi-layer composite pipe has high heat resistance temperature, good thermal conductivity, tight interlayer bonding, simple production process, long service life, environmental protection of polyvinylidene fluoride pipes, less precipitation and good chemical stability, high impact resistance, wear resistance, creep resistance, mechanical strength and toughness, good heat resistance, long-term use temperature of 20100 degrees C, smooth surface, less fluid resistance, and outstanding oxygen barrier performance. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing the multi-layer composite pipe, which involves adding different materials separately to three extruders for forming the inner layer, middle layer and outer layer, adding fluoroolefin polymer pellets into the extruder used to form the inner layer to form outer layer, adding polyethylene pellets to the extruder of the layer, and adding alloy pellets to the extruder used to form middle layer, using three extruders to respectively extrude the inner layer, middle layer and outer layer, and forming an unshaped three-layer composite pipe through the same composite extrusion die at one time, cutting the unshaped three-layer composite pipe after vacuum sizing, and then heat-setting in an oven to obtain a three-layer composite pipe.