Method for preparing high-strength heat-resistant and cold-resistant modified polypropylene pipe

The invention discloses a method for preparing a high-strength heat-resistant and cold-resistant modified polypropylene pipe. The pipe is formed by the following steps of: extruding an outer layer, a middle transition layer and an inner wall layer onto the same one mold through three extruders, fusing and compounding. The outer layer of the pipe consists of modified polypropylene, an impact-resistant modifying agent, an antibacterial agent, a light stabilizer, an antioxygen, a compatibilizer, nanometer materials, a tackifier and a color masterbatch in parts by weight; the middle transition layer of the pipe consists of engineering plastics, the modified polypropylene, the compatibilizer, the a tackifier and the color masterbatch in parts by weight; and the inner wall layer of the pipe consists of the engineering plastics, the modified polypropylene, the compatibilizer, a fortifier, a filler, the nanometer materials and the color masterbatch in parts by weight. Compared with traditional similar pipes, the operating temperature of the pipe prepared by the method disclosed by the invention is improved by 30-70 DEG C; the cold-resistant temperature is lowered by minus 15-minus 30 DEG C; the pressure-resistant property is improved by 30-50 percent; the creep resistance is improved by 100-200 percent; the service life is prolonged by 10-20 years; and the wall thickness of the pipe is reduced by 20-50 percent.