Low density polyethylene drip irrigation pipe for farmland
DATE：2022/8/17 9:06:02 / READ： / SOURCE：This station
Low density polyethylene drip irrigation pipe for farmland
5.2.6 low density polyethylene calcium plastic pipe
Low density polyethylene calcium plastic pipe is a kind of plastic pipe with low price, certain rigidity and impact strength of - 254 degrees, which is not easy to be damaged and has wide application prospects. (1) Raw material selection: low density polyethylene calcium plastic pipe mainly uses low density polyethylene (with melt flow rate of 0.30 ~ 0.60g / 10min) resin and heavy calcium carbonate as raw materials, and then adds some auxiliary raw material combinations to plasticize and extrude. The reference formula of the materials for extrusion molding this calcium plastic pipe is as follows (parts by mass). Low density polyethylene resin (LDPE) 100 liquid paraffin (white oil). (2) Calcium plastic pipe extrusion molding process: various raw materials are metered into the high-speed mixer according to the formula (mixing temperature: 45 ~ 55 ℃, mixing and stirring for about 5min) → transported to the internal mixer for mixing and pre plasticizing (temperature: 60 ~ 70 ℃, mixing for about 3min) → mixed on the first open mixer (temperature: 65 ~ 75 ℃, mixing for about 2min) → mixed, tablet pressed Coiling (the mixing temperature is 60 ~ 70 ℃, and the distance between the two rollers is about 2mm) → after the sheet is cooled, use the pelletizer to cut the granules, and then sift out the granules with too small or too large specifications, Finally, bagging → extrusion plasticizing to form calcium plastic pipe (the extrusion molding of calcium plastic pipe is basically similar to the extrusion molding method of polyethylene general pipe by using extruder, molding die and process temperature control. However, attention should be paid to the selection of extrusion screw. Since CaCO3 raw material wears the screw quickly, boronizing screw with high hardness and wear resistance should be selected). 527 linear low density polyethylene flame retardant pipe compared with low density polyethylene pipe, linear low density polyethylene pipe is a kind of plastic pipe with high tensile strength, high toughness (about 50% higher), excellent environmental stress cracking resistance and low temperature resistance, and relatively low price. In order to make this plastic pipe become the protective sleeve of wire and cable, a certain proportion of flame retardant and auxiliary materials are added to its resin to become a linear low-density polyethylene flame retardant pipe. Quantity: in order to improve the mixing quality and flame retardancy of flame retardant and resin, some coupling agents and dispersants are added to the flame retardant (the amount is about 1.5% of the flame retardant)] and placed in a high-speed mixer with a certain temperature for pre mixing → various raw materials and additives are metered and added to the high-speed mixer (the temperature is about 90 ℃), Stir and mix evenly - extrude, mix and granulate (use the equidistant depth progressive screw, and the process temperature is controlled within the range of 150 ~ 180 ℃) → extrude and form pipes (use the single screw general-purpose extruder, the screw is the equidistant depth progressive screw, the length diameter ratio is 20:1, and the compression ratio is 2.5. The structure of the molding die is the same as that of the polyethylene general-purpose pipe molding die). (2) The molding process temperature is 110 ~ 130 ℃ in the barrel feeding section, 140 ~ 160 ℃ in the plasticizing section, and 160 ~ 180 ℃ in the homogenizing section. Molding die 160 ~ 170 ℃.
5.2.8 polyethylene composite pipe
The composite plastic pipe refers to the plastic pipe extruded by two or more different types of resins and the plastic pipe extruded by two different density polyethylene resins, which is called ethylene composite pipe. Polyethylene composite pipe is a kind of plastic pipe that can withstand certain pressure and has strong corrosion resistance. It is mainly used in oil and gas transportation and mine ventilation pipeline. In corrosive liquid (gas) transportation such as low-pressure gas brine, carbon dioxide and crude oil, there is a tendency to gradually replace steel pipes. (1) The inner layer of the composite pipe is made of low-density polyethylene resin (melt flow rate: 2-7g / 10min) and the outer layer is made of high-density polyethylene resin (melt flow rate: 3-8g / 10min). (2) Production process sequence: low-density polyethylene extrusion melting high-density polyethylene extrusion melting forming composite pipe cooling and setting with mold → traction → cutting → inspection → weighing and warehousing (3) single screw universal extruder is used for the extrusion of preparation B and high-density polyethylene. The screw structure of extruded LDPE resin is of constant distance and varying depth, with length diameter ratio of 20 ∶ 1 and compression ratio of 2 ~ 3. The screw structure for extrusion of HDPE resin is the same as that for extrusion of LDPE, but the length diameter ratio is (25 ~ 30): 1, and the screw diameter is larger than that for extrusion of LDPE.
Author：admin