PVC/CPVC hybrid modified heat shrinkable tube

日期:2021/9/17 8:33:33 / 阅读: / 来源:本站

PVC/CPVC hybrid modified heat shrinkable tube
        The connection of insulated wires, especially the close and beautiful connection of two insulated wires with different diameters, should use heat shrinkable tubing. Commonly used heat-shrinkable tubes include PC heat-shrinkable tubes and PE heat-shrinkable tubes. The advantages of PC heat shrinkable tube are flame retardant, good flexibility, but low heat shrinkage rate, which is not suitable for the connection of insulated wires with large diameter differences. The heat shrinkage rate of PE heat shrinkable tube is higher, but the disadvantage is that it is flammable and When curing with electron irradiation, the surface is uneven and the appearance is poor. The PVC resin and CNC resin are mixed and used, and polytetrafluoroethylene powder and corresponding additives are added at the same time to prepare a heat shrinkable tube. The tube is non-flammable, soft, has a high thermal shrinkage rate, a tight and beautiful wire joint, and will not break under high temperature.

       1. Material selection and formula design

       (1) PVC material, average polymerization degree 1300, industrial grade; PVC, average polymerization degree 2500, industrial grade; CPVC, chlorine content 63%, industrial grade; DOP, industrial grade; PN150, produced by Dainippon Ink Industry Co., Ltd.; poly Tetrafluoroethylene powder, technical grade; tribasic lead sulfate (trisalt), technical grade; stearic acid, technical grade; clay, technical grade; light CaCO3, technical grade.
       (2) Analysis of raw material quality and ratio. The average degree of polymerization of PVC resin is 800-3000, preferably 1200-1500. Within this range, the processing performance is good. The chlorine content of CPVC resin is less than or equal to 70%. If it exceeds 70%, the processing performance and thermal stability will become poor. The chlorine content is preferably 63% to 65%. The mass ratio of PVC resin to CPC resin is preferably 90:1050:50. If the amount of PVC resin is more than 9 parts and CPVC resin is less than 10 parts, the shrinkage rate will decrease. If the amount of PNC resin is less than 50 parts, and the amount of CPNC is more than 50 parts, the processing performance will become poor.
       The amount of polytetrafluoroethylene is preferably 1-10 parts per 100 parts of basic resin (ie PC resin and CPC. resin). If it is less than 1 part, the tube is easy to break during expansion; if it is more than 10 parts, the mechanical properties and extrusion processing performance of the compound are not good. The best dosage is 3 parts. The amount of plasticizer added is based on the product hardness and resistance. It depends on the thermal properties, and the general dosage is 400 servings. The heat stabilizer is a three-salt, preferably three-salt, dibasic lead stearate, lead stearate and calcium stearate, four kinds of heat stabilizers are used in combination, because there is a "synergistic effect" between them.

      2. Main equipment
       Banbury mixer, single screw extruder granulator, single screw extruder, expansion rate and heat sink rate detection device.
     3. Preparation process
      (1) Process flow ingredients → banburying → granulation → squeeze tube → measurement of expansion rate and measurement of thermal shrinkage rate.
      (2) Molding process
       1) Ingredients. Ingredients according to formula requirements.
       2) Tantra. Put the prepared materials in a Banbury mixer to mix the components evenly.
       3) Granulation. Put the mixed material into a single-screw extruder granulator for granulation. 4) Squeeze the tube. Put the pellets into a single-screw extruder and extrude into a tube; the temperature of the extruder is 140-170°C.

作者:admin


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