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CN-122011617-A - Toughened ultra-soft low-temperature-resistant PVC sheath, cable and preparation method thereof

CN122011617ACN 122011617 ACN122011617 ACN 122011617ACN-122011617-A

Abstract

The invention relates to a toughened ultra-soft low-temperature-resistant PVC sheath, a cable and a preparation method thereof. The method comprises the steps of high-speed mixing and premixing with a main plasticizer, soft segment-inorganic high-shear pre-dispersing, double-screw melting and mixing, granulating, extruding a sheath, molding and coating a conductor. The inorganic flame-retardant/smoke-suppressing particle refining and coating structure realized by the flexible medium can obviously improve the low-temperature flexibility and toughening performance of a PVC system, and combines a multiphase synergistic toughening system and reasonable melt mixing conditions, so that the sheath material keeps excellent bending performance at deep low temperature, also has flame-retardant performance and environmental protection compliance, and meets the comprehensive use requirements in cold areas and severe working conditions.

Inventors

  • CHEN YADAN
  • CHEN JIAJIE
  • Jin Hangdong

Assignees

  • 浙江宏策电缆有限公司

Dates

Publication Date
20260512
Application Date
20260129

Claims (10)

  1. 1. The preparation method of the toughened ultra-soft low-temperature-resistant PVC sheath composition is characterized by comprising the following steps of: s1, adding PVC resin, trioctyl esterified trimesic acid ester and polyester type high polymer plasticizer into a high-speed mixer, and premixing for 3-5 min at the temperature of 90-115 ℃ to obtain a premix A; S2, heating polycaprolactone diol and epoxidized soybean oil to 60-90 ℃ to form a flexible liquid, sequentially adding layered double hydroxide and surface-treated nano calcium carbonate into the flexible liquid under a high shearing condition, and mixing and dispersing for 10-30 min according to the mass ratio of (0.6-1.4) to 1, so that the volume average particle size D 50 of the layered double hydroxide and the nano calcium carbonate is less than or equal to 1.0 mu m, and obtaining a flexible-inorganic composite dispersion B; S3, sequentially adding the premix A, the composite dispersion B, the liquid nitrile rubber, the core-shell toughening agent, the chlorinated polyethylene, the aluminum phosphinate, the zinc borate, the calcium zinc composite stabilizer, the internal and external lubricants and the antioxidant into a double-screw extruder for melt mixing, extruding, water-cooling bracing and granulating to obtain a sheath composition granule C; s4, extruding and molding the sheath composition granules on an extruder to obtain the toughened ultra-soft low-temperature-resistant PVC sheath or extruding and wrapping the conductor to form a cable sheath layer.
  2. 2. The method according to claim 1, wherein the mass ratio of the trioctyl trimesic acid ester to the polyester type polymer plasticizer in the step S1 is (1.2-2.5) to 1.
  3. 3. The method according to claim 1, wherein the polycaprolactone diol in step S2 has a number average molecular weight of 1000 to 1500 and a hydroxyl value of 70 to 115mgkoh/g.
  4. 4. The method according to claim 1, wherein in the step S2, the layered double hydroxide is Mg-Al-CO 3 hydrotalcite, the volume average particle diameter D 50 is 200-500 nm, the specific surface area is 10-30 m 2 /g, and the surface of the nano calcium carbonate is treated by fatty acid and/or silane coupling agent.
  5. 5. The method of claim 1, wherein in the step S3, the mass fraction of acrylonitrile of the liquid nitrile rubber is 18-26%, the core-shell toughening agent is methacrylic acid-butadiene-styrene core-shell toughening agent and/or acrylic ester core-shell toughening agent, and the mass ratio of the liquid nitrile rubber to the core-shell toughening agent is (0.5-1.2) to 1.
  6. 6. The method according to claim 1, wherein the mass ratio of the aluminum hydride phosphinate to the zinc borate in the step S3 is 3-5:1.
  7. 7. The method according to claim 1, wherein in the step S3, the temperature of each barrel area of the twin-screw extruder is controlled to be 150-170 ℃, the temperature of a machine head is controlled to be 155-170 ℃, a vacuum degree of-0.06 to-0.09 MPa is applied to a vacuum exhaust port, the specific energy input per unit mass of material is 0.15-0.30 kwh/kg, and the online torque fluctuation of the extruder is not more than +/-10% of the stable torque value.
  8. 8. The method according to claim 1, wherein the volatile matter of the pellets C is less than or equal to 0.3wt% after the pellets C are dried by hot air at 60-80 ℃ for 1-3 hours.
  9. 9. The method of any one of claims 1 to 8, wherein the components in the step S2 and the step S3 are added in an amount of 6 to 14 parts by mass of polycaprolactone diol, 3 to 8 parts by mass of liquid nitrile rubber, 4 to 9 parts by mass of core-shell toughening agent, 2 to 6 parts by mass of chlorinated polyethylene, 3 to 6 parts by mass of layered double hydroxide, 4 to 8 parts by mass of surface-treated nano calcium carbonate, 10 to 18 parts by mass of aluminum phosphinate, 2 to 6 parts by mass of zinc borate, 3 to 7 parts by mass of epoxidized soybean oil, 2 to 3 parts by mass of calcium-zinc composite stabilizer, 0.3 to 1.0 part by mass of conventional internal and external lubricant and 0.1 to 0.4 part by mass of antioxidant.
  10. 10. The cable is characterized by comprising a conductor, an insulating layer and an outer sheath, wherein the outer sheath is obtained by extrusion molding of the toughened super-soft low-temperature-resistant PVC sheath composition prepared by the method of any one of claims 1-8.

Description

Toughened ultra-soft low-temperature-resistant PVC sheath, cable and preparation method thereof Technical Field The invention belongs to the technical field of cables, and particularly relates to a toughened ultra-soft low-temperature-resistant PVC sheath, a cable and a preparation method thereof. Background Polyvinyl chloride (PVC) is widely used as an insulation and sheath material for wires and cables for a long time due to wide sources of raw materials, low cost, wide processing window and certain flame retardance. Conventional processes have been able to meet the basic requirements of mechanical, flame retardant and electrical properties. However, in the occasions such as wiring in cold areas, outdoor low-temperature environments, robot drag chains, cold houses, low-temperature logistics and the like, the sheath material also needs to keep good flexibility and crack resistance under the low-temperature conditions, and meanwhile, has the advantages of single vertical combustion, no flame retardation, long-term electrical stability and compliance with environmental protection regulations such as lead-free, antimony reduction and the like. Therefore, more inorganic flame-retardant/smoke-suppressing filler and rubber phase or soft segment resin are often required to be introduced into the PVC sheath material to adjust the low-temperature performance, so that higher requirements are put on the cooperative control of the formula structure and the preparation process. Chinese patent CN103205070A discloses a cold-resistant oil-resistant flame-retardant polyvinyl chloride cable material and a preparation method thereof, wherein the cable material consists of PVC resin powder, a plasticizer, nitrile rubber powder, a stabilizer, epoxidized soybean oil, a flame retardant, elvaloy, an antioxidant, a lubricant and the like, and the cable material is obtained by uniformly stirring the raw materials in a high-speed mixer, banburying the raw materials in a temperature range of 125-140 ℃, extruding by a double screw, hot cutting and granulating, cooling and sieving. According to the scheme, nitrile rubber powder and a specific plasticizing system are introduced into the formula, and the conventional high-speed mixing, banburying and double-screw extrusion process route is matched, so that the cold resistance and oil resistance of the PVC cable material can be improved to a certain extent, and the flame retardant property is improved. However, the process control is mainly concentrated on the mixing temperature and banburying temperature interval, and no specific process design and parameter window are given for the dispersion state of a high-filling inorganic flame-retardant/smoke-suppressing system in a matrix, particle size control, energy input and volatile component control in the melting and mixing process, and no process path for realizing lower-temperature-level (such as-50 ℃) flexibility and single vertical combustion non-delayed combustion under an antimony-free system is involved. It can be seen from the comprehensive prior art that the preparation method of the PVC sheath material adopts a basic route of high-speed mixing, banburying or double-screw extrusion granulation in the prior art, and the mechanical property and processing stability of the material are improved by adjusting the mixing temperature, the extrusion temperature and the addition sequence of the PVC and the plasticizer. Part of the literature introduces flexible phases such as nitrile rubber powder and chlorinated polyethylene or synergistic systems such as halogen-containing flame retardants and antimony trioxide to achieve both cold resistance and flame retardance. However, for realizing high-efficiency dispersion and interface structure construction between the inorganic flame-retardant/smoke-suppressing filler and the soft segment phase by a process means under the conditions of no antimony and high inorganic filling, controlling the microscopic morphology of the material, reducing volatile matters and ensuring the combination property of deep low-temperature bending property and single vertical combustion non-delayed combustion, no systematic solution has been given out in the prior art. Therefore, on the premise of not changing the overall cost of the PVC system and processing equipment, how to further improve the deep low-temperature flexibility, toughness and crack resistance of the cable and also consider the flame retardant property and the environment-friendly compliance so as to meet the comprehensive use requirements in cold areas and severe working conditions is still a technical subject faced by the person skilled in the art. Disclosure of Invention In order to solve the technical problems, the invention provides the preparation process of the ultra-soft low-temperature-resistant PVC sheath, which can simultaneously realize the deep low-temperature flexibility, toughening and cracking resistance collaborative promotion of the