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CN-121975215-A - High-toughness flame-retardant cable protection tube and preparation method thereof

CN121975215ACN 121975215 ACN121975215 ACN 121975215ACN-121975215-A

Abstract

The invention discloses a high-toughness flame-retardant cable protection tube and a preparation method thereof, comprising the following steps of S1, carrying out melt blending and dynamic vulcanization reaction on a mixture containing bimodal high-density polyethylene, a polyolefin elastomer with a double long-chain branched structure and a dynamic cross-linking agent in a first temperature range and under first shearing strength to obtain a pre-crosslinked base material, S2, cooling the pre-crosslinked base material to an interface anchoring temperature range, adding a composite fiber system, carrying out melt blending in a first stage under medium shearing strength, S3, heating the mixture obtained in the step S2 to a second temperature range, and raising the temperature to second shearing strength to carry out high-shear melt blending in a second stage, and simultaneously adding a halogen-free intumescent flame-retardant system and a multi-wall carbon nano tube, and S4, orientation locking and gradient molding. The polyolefin elastomer with the double long branched chain structure is introduced, and the low-temperature impact strength, toughness and flame retardant grade of the material can be obviously improved by adopting a step process.

Inventors

  • QIAN HUIFANG
  • ZHOU JIANG
  • XIA LANLAN
  • YANG QIAN
  • DAI JIE

Assignees

  • 苏州盛信管业有限责任公司

Dates

Publication Date
20260505
Application Date
20260313

Claims (10)

  1. 1. The preparation method of the high-toughness flame-retardant cable protection tube is characterized by comprising the following steps of: S1, dynamic crosslinking and network construction steps: Carrying out melt blending and dynamic vulcanization reaction on a mixture containing bimodal high-density polyethylene, a polyolefin elastomer with a double long-chain branched structure and a dynamic crosslinking agent in a first temperature range under a first shearing strength, so that H-type chemical cross-linked long-chain branched chains in the polyolefin elastomer with the double long-chain branched structure are crosslinked, and meanwhile, T-type crystalline long-chain branched chains form physical crosslinking points to form a physical-chemical bicontinuous interpenetrating network structure together with the bimodal high-density polyethylene, so as to obtain a pre-crosslinked base material; S2, an interface anchoring and gradient interface construction step: cooling the pre-crosslinked base material obtained in the step S1 to an interface anchoring temperature range, adding a composite fiber system compounded by aluminate modified fibrous brucite and titanate modified fibrous brucite, carrying out melt blending in the first stage under medium shear strength, enabling the interfaces of the two modified fibers and the pre-crosslinked base material to be chemically anchored and physically entangled, forming a gradient interface layer of a rigid inner layer and a flexible outer layer on the surface of the fiber in situ, and realizing pre-dispersion; S3, orientation, functionalization and compounding: Heating the mixture obtained in the step S2 to a second temperature range, and raising the temperature to a second shearing strength to perform high-shearing melt blending of a second stage, and simultaneously adding a halogen-free intumescent flame retardant system and multi-wall carbon nanotubes, wherein the second shearing strength is higher than the first shearing strength, the flow field strength is sufficient to enable the anchored fibrous brucite to be aligned, and the multi-wall carbon nanotubes form a conductive network in a matrix; s4, orientation locking and gradient forming: And (3) extruding the material obtained in the step (S3) through a tapered runner die with gradual temperature field control to form a pipe.
  2. 2. The method for preparing a high-toughness flame-retardant cable protective tube according to claim 1, wherein in the step S1, the first temperature range is 160-175 ℃, and the first shear strength corresponds to a screw rotation speed of 100-200rpm.
  3. 3. The preparation method of the high-toughness flame-retardant cable protection tube according to claim 1, wherein in the step S1, the dynamic cross-linking agent is a compound of dicumyl peroxide and triallylisocyanurate, and the mass ratio of the dicumyl peroxide to the triallylisocyanurate is (1:1) - (1:1.5).
  4. 4. The method for preparing a high-toughness flame-retardant cable protective tube according to claim 1, wherein in the step S2, the interfacial anchoring temperature interval is 150-165 ℃, the length-diameter ratio of the aluminate-modified fibrous brucite and the titanate-modified fibrous brucite is more than 50, the activation rate is not less than 95%, and the medium shear strength corresponds to the screw rotation speed of 200-280rpm.
  5. 5. The method for producing a high-toughness flame-retardant cable protective tube according to claim 1, wherein in step S3, the second temperature range is 175-190 ℃, and the second shear strength corresponds to a screw rotation speed of 300-450rpm.
  6. 6. The method for preparing the high-toughness flame-retardant cable protection tube according to claim 1, wherein in the step S3, the halogen-free intumescent flame retardant system is a mixture of microencapsulated ammonium polyphosphate, melamine cyanurate and zinc borate, and the weight ratio of the three is (8-20): 4-10): 1-8.
  7. 7. The method for preparing a high-toughness flame-retardant cable protection tube according to claim 1, wherein in step S4, the temperature of the tapered runner mold is controlled as follows: The temperature of the inlet area is 180-190 ℃, the temperature of the middle compression area is 170-180 ℃, the temperature of the die area is 150-160 ℃, and the oriented structure part of the fibrous brucite is frozen in the pipe wall through a temperature gradient, so that the gradient microstructure with high radial orientation of the surface layer fibers and random distribution of the core layer fibers is formed.
  8. 8. A high-toughness flame-retardant cable protective tube prepared by the method for preparing the high-toughness flame-retardant cable protective tube according to any one of claims 1 to 7.
  9. 9. The high-toughness flame-retardant cable protective tube according to claim 8, comprising the following raw materials in parts by weight: 60-80 parts of bimodal distribution high density polyethylene 20-35 Parts of polyolefin elastomer with double long branched chain structure 0.5-3 Parts of dynamic cross-linking agent 5-9 Parts of aluminate modified fibrous brucite Titanate modified fibrous brucite 1-4 parts 10-18 Parts of halogen-free intumescent flame retardant system 0.5-3 Parts of multiwall carbon nanotube 0.5-3 Parts of weather-resistant stabilizer 0.1 To 1 part of fluorine-containing processing aid 0.5-2 Parts of hyperbranched polyethylene.
  10. 10. The high-toughness flame-retardant cable protective tube according to claim 8, wherein the flame retardant rating of the high-toughness flame-retardant cable protective tube reaches UL 94V-0 level, the notch impact strength is more than or equal to 25kJ/m 2 , and the tensile strength is more than or equal to 25MPa.

Description

High-toughness flame-retardant cable protection tube and preparation method thereof Technical Field The invention belongs to the technical field of polymer composite materials, and particularly relates to a high-toughness flame-retardant cable protection tube and a preparation method thereof. Background The high polymer composite material cable protection pipe is widely applied to the fields of power, communication and the like. With the development of severe application environments such as ultra-high voltage transmission, offshore wind power, severe cold areas and the like, higher requirements are put on the comprehensive performance of the protection pipe, namely the protection pipe is required to have excellent high toughness, rigidity, halogen-free flame retardance, long-term environmental stress cracking resistance and the like. In recent years, halogen-free flame retardant polyolefin composites have become a research hotspot. However, there is a technical contradiction which is not solved effectively for a long time, namely, the dynamic vulcanization toughening technology and the high-efficiency expansion flame retardant technology are difficult to cooperate in a single system. Disclosure of Invention The invention aims to solve the problems in the prior art and provide a high-toughness flame-retardant cable protection tube and a preparation method thereof. In order to achieve the above purpose and achieve the above technical effects, the invention adopts the following technical scheme: the preparation method of the high-toughness flame-retardant cable protection tube comprises the following steps: S1, dynamic crosslinking and network construction steps: Carrying out melt blending and dynamic vulcanization reaction on a mixture containing bimodal high-density polyethylene, a polyolefin elastomer with a double long-chain branched structure and a dynamic crosslinking agent in a first temperature range under a first shearing strength, so that H-type chemical cross-linked long-chain branched chains in the polyolefin elastomer with the double long-chain branched structure are crosslinked, and meanwhile, T-type crystalline long-chain branched chains form physical crosslinking points to form a physical-chemical bicontinuous interpenetrating network structure together with the bimodal high-density polyethylene, so as to obtain a pre-crosslinked base material; S2, an interface anchoring and gradient interface construction step: cooling the pre-crosslinked base material obtained in the step S1 to an interface anchoring temperature range, adding a composite fiber system compounded by aluminate modified fibrous brucite and titanate modified fibrous brucite, carrying out melt blending in the first stage under medium shear strength, enabling the interfaces of the two modified fibers and the pre-crosslinked base material to be chemically anchored and physically entangled, forming a gradient interface layer of a rigid inner layer and a flexible outer layer on the surface of the fiber in situ, and realizing pre-dispersion; S3, orientation, functionalization and compounding: Heating the mixture obtained in the step S2 to a second temperature range, and raising the temperature to a second shearing strength to perform high-shearing melt blending of a second stage, and simultaneously adding a halogen-free intumescent flame retardant system and multi-wall carbon nanotubes, wherein the second shearing strength is higher than the first shearing strength, the flow field strength is sufficient to enable the anchored fibrous brucite to be aligned, and the multi-wall carbon nanotubes form a conductive network in a matrix; s4, orientation locking and gradient forming: And (3) extruding the material obtained in the step (S3) through a tapered runner die with gradual temperature field control to form a pipe. Further, in step S1, the first temperature range is 160-175 ℃, and the first shear strength corresponds to a screw rotation speed of 100-200rpm. In step S1, the dynamic cross-linking agent is a compound of dicumyl peroxide and trialkenyl isocyanurate, and the mass ratio of the dicumyl peroxide to the trialkenyl isocyanurate is (1:1) - (1:1.5). Further, in the step S2, the interfacial anchoring temperature range is 150-165 ℃, the length-diameter ratio of the aluminate-modified fibrous brucite and the titanate-modified fibrous brucite is more than 50, the activation rate is not less than 95%, and the medium shear strength corresponds to the screw rotating speed of 200-280rpm. Further, in step S3, the second temperature range is 175-190 ℃, and the second shear strength corresponds to a screw rotation speed of 300-450rpm. Further, in the step S3, the halogen-free intumescent flame retardant system is a mixture of microencapsulated ammonium polyphosphate, melamine cyanurate and zinc borate, and the weight ratio of the three is (8-20): 4-10): 1-8. Further, in step S4, the temperature of the tapered runner mold is controlled as follo