Polyethylene heat shrinkable pipe
DATE：2022/8/23 9:31:24 / READ： / SOURCE：This station
Polyethylene heat shrinkable pipe
Crosslinked polyethylene heat shrinkable pipe is a kind of product in which polyethylene is crosslinked and modified, and then expanded and shaped. In application, when the tube is reheated at a certain temperature, it has the characteristics of heat shrinkage. Using the heat shrinkage characteristics of cross-linked polyethylene heat shrinkable pipe, this pipe is used as the joint protection sleeve of electric wire and cable, the insulation protection sleeve of electric instrument and the joint protection sleeve of petrochemical pipeline. In addition, it can also be used as the covering sleeve of the handle of the club and fishing rod. During application, the plastic pipe is sheathed at the required protection place, and after heating, the pipe is tightly wrapped at the application place, which is very convenient, safe and reliable. (1) Selection of raw materials and cross-linking method low density polyethylene is mainly used for the formation of cross-linked polyethylene heat shrinkable pipe, with density ≥ 0.918g/cm3 and melt flow rate MFR = 1.5 ~ 3G / 10min. Radiation crosslinked polyethylene, peroxide crosslinked polyethylene and silane crosslinked polyethylene can be used as crosslinking methods of polyethylene. Here, only the production and molding methods of silane crosslinked polyethylene heat shrinkable pipe are introduced. The main raw material of silane crosslinked polyethylene heat shrinkable pipe is low density polyethylene. Vinyl trimethoxysilane (VTEs), vinyl tris (2 methoxyethoxy) silane (vtmes), Of which: (VTMS hydrolysis speed is the fastest. The amount of silane in the formula is generally controlled at 1% ~ 3%. If the amount is too much, the surface of the product will frost and the strength will decrease; if the amount is too small and the grafting is uneven, the reaction temperature needs to be increased, i.e. the crosslinking degree of raw materials in the barrel is increased. The formula of silane crosslinked polyethylene heat shrinkable tube forming material is as follows, which can be used for reference. ① general purpose silane crosslinked polyethylene heat shrinkable tube material formula low density polyethylene LD 100 parts of PE (density 0.922g/cm3, melt flow rate MFR = 2G / 10min), 0.03 parts of diisopropylbenzene peroxide (DCP), 2 parts of vinyl triethoxysilane (VTEs), 0.125 parts of dibutyltin dilaurate (DBTL), 10100.13 parts of antioxidant, 0.25 parts of antioxidant THIODIPROPIONIC acid (DSTP), and an appropriate amount of lubricant and ultraviolet absorber. ② The material formula of silane crosslinked polyethylene heat shrinkable cable sheath is 100 parts of low-density polyethylene (LDPE) (density: 0922g / cm, melt flow rate: MFR = 2G / 10min), 0.05 parts of diisopropylbenzene peroxide (DCP), 2 parts of vinyl triethoxysilane (VTEs), 0.13 parts of dibutyltin dilaurate (DBTL), 10100.1 parts of antioxidant, 0.35 parts of antioxidant THIODIPROPIONIC acid (DSTP), 26 parts of carbon black, and an appropriate amount of lubricant and ultraviolet absorber, Appropriate amount of antimony trioxide (sb2o). ③ The material formula of silane crosslinked polyethylene flame retardant heat shrinkable pipe is 100 parts of low density polyethylene (LDPE) (degree: 0922g / cm, melt flow rate: MFR = 2G / 10min), 2 parts of vinyl triethoxysilane (VTEs), 0.04 parts of diisopropylbenzene peroxide (DCP), 013 parts of dibutyltin dilaurate (BL), 10100.13 parts of antioxidant, 0.25 parts of antioxidant THIODIPROPIONIC acid (DSTP), 3 parts of decabromodiphenyl ether (FR-10), 7 parts of hexabromocyclododecane (HBCD), and 4 parts of antimony trioxide (sbzo3), Proper amount of lubricant and ultraviolet absorber. (2) The process conditions of acetalization are the same as those of silane crosslinked polyethylene pipe. The difference is that the production of silane crosslinked polyethylene pipe can be completed by adding a pipe expansion process after the extrusion molding crosslinking process of silane crosslinked polyethylene pipe. Chapter 5 the production process sequence and various process parameters in the extrusion molding of silane crosslinked polyethylene heat shrinkable pipe by plastic pipe extrusion can be produced according to the process parameters and conditions in the molding of silane crosslinked polyethylene pipe. (3) The pipe expanding and shaping process of silane crosslinked polyethylene heat shrinkable pipe is carried out after the polyethylene is extruded and then cross-linked into a crosslinked polyethylene pipe. The expanding and shaping production process of this kind of pipe is relatively simple. If the intermittent expansion type is adopted, as long as the pipe is heated to the softening point temperature, and then the expansion rod is pulled into the pipe with steel wire (generally, the diameter of the expansion rod is about twice the diameter of the expanded pipe), the pipe will be expanded by the expansion rod diameter larger than its own inner diameter. At this time, the tube is cooled and shaped. Then the expansion rod is pulled out from the expanded plastic pipe to complete the expansion and shaping of the pipe. The schematic diagram of this method is shown in Fig. 5-24. Fig. 5-24 a traction heating steel wire bundle of intermittent pipe expanding device 1; 2. A plastic pipe; 3-expansion rod if the expansion production process needs to be carried out continuously, the expansion can be carried out as shown in Fig. 5-25. During production, the expanded pipe is added in the airtight containerAfter the water inlet is thermally softened (the internal and external pressure balance of the expanded pipe shall be controlled here), it enters into the sizing sleeve. If the inner diameter of the sizing sleeve is larger than the outer diameter of the expanded pipe (generally about one time larger), the compressed air in the pipe will blow the pipe (the sizing sleeve is provided with an exhaust port) and close to the inner wall of the sizing sleeve; There is circulating cooling water in the sizing sleeve, and the water outlet cools and shapes the expanded plastic pipe to complete the expansion 1-plastic pipe of the silane crosslinked polyethylene heat shrinkable pipe of the continuous expansion device shown in Fig. 5-25; 2. Inlet of fixed diameter sleeve; Production. 3 fixed diameter sleeve; At present, there is no quality standard for silane crosslinked polyethylene heat shrinkable pipe in China. Table5-20 shows the specifications and sizes of crosslinked polyethylene heat shrinkable pipes produced by some enterprises, which can be used for reference. Table 5-21 lists the properties of polyethylene heat shrinkable pipes made in Japan.
Author：admin