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CN-121975221-A - Crosslinked polyethylene insulated wire with low-temperature frost crack prevention function

CN121975221ACN 121975221 ACN121975221 ACN 121975221ACN-121975221-A

Abstract

The application relates to the technical field of wire and cable manufacture, and discloses a crosslinked polyethylene insulated wire with a low-temperature frost crack prevention function, the insulating layer of the crosslinked polyethylene insulated wire comprises linear low density polyethylene, ethylene-1-octene copolymer elastomer, porous linear low density polyethylene carrier resin, fluorine-containing polymer processing aid and homogeneous phase active mixed solution. The homogeneously active mixed liquid consists of vinyl silane, 1-octadecene, high vinyl liquid polybutadiene, initiator, etc. and is adsorbed inside porous carrier resin to prepare the dry silane mother material. The components are melted and grafted in a double-screw extruder and are formed by coating, solidifying and crosslinking treatment. According to the application, the flexible crosslinking node is constructed by introducing 1-octadecene and polybutadiene, and the physical limit of the carrier resin and the high-pressure airtight foam inhibition process of the extruder are combined, so that the insulating layer has the anti-brittle fracture capability at-40 ℃, and meanwhile, the high-temperature dimensional stability and the low dielectric loss characteristic are maintained.

Inventors

  • Ning Liqing
  • GENG LICHUAN
  • ZHAO MEILING
  • GENG SONGSONG
  • MA YUANLING
  • LI XIJIAO
  • Li Xicha
  • Bo Jinyang
  • Feng Honghong
  • WANG SHANSHAN
  • ZHAO BINGYAN
  • ZHAO JIANGXIN
  • YAN CONGCONG

Assignees

  • 友惠线缆有限公司

Dates

Publication Date
20260505
Application Date
20260318

Claims (10)

  1. 1. The crosslinked polyethylene insulated wire with the low-temperature frost crack prevention function is characterized in that an insulating layer of the crosslinked polyethylene insulated wire is prepared from the following raw materials in parts by weight: 55.0-82.0 parts by weight of linear low density polyethylene; 10.0-30.0 parts by weight of an ethylene-1-octene copolymer elastomer; 8.0-15.0 parts by weight of porous linear low-density polyethylene carrier resin; 0.02-0.10 parts by weight of a fluorine-containing polymer processing aid; 3.29-9.31 parts by weight of homogeneous phase active mixed solution; the porous linear low-density polyethylene carrier resin is mixed with the homogeneous phase active mixed solution in advance and adsorbed to prepare a dry silane master batch, and then the dry silane master batch is extruded and molded; The homogeneously active mixed solution comprises: 1.0-3.0 parts by weight of vinyl tri (2-methoxyethoxy) silane; 0.2-1.0 part by weight of 1-octadecene; 2.0-5.0 parts by weight of high vinyl liquid polybutadiene; 0.05-0.15 parts by weight of a first-stage initiator; 0.02-0.08 parts by weight of a second-stage initiator; and 0.02-0.08 parts by weight of a silane crosslinking catalyst.
  2. 2. The crosslinked polyethylene insulated wire having a low-temperature frost crack prevention function according to claim 1, wherein the gel content of the insulating layer is not less than 79%, the thermal elongation under a load of 200 ℃ and 20N/cm 2 is not more than 70%, and the elongation at break of the insulating layer under a load of-40 ℃ is not less than 165%, and the dielectric loss tangent under a load of 90 ℃ is not more than 5.0x10 -4 .
  3. 3. The crosslinked polyethylene insulated wire with the low-temperature frost-crack prevention function according to claim 1, wherein the first-stage initiator is tert-butyl peroxybenzoate, the second-stage initiator is 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane, the silane crosslinking catalyst is dibutyltin dilaurate, and the fluorine-containing polymer processing aid is a copolymer of vinylidene fluoride and hexafluoropropylene.
  4. 4. The crosslinked polyethylene insulated wire with the low-temperature frost crack prevention function according to claim 1, wherein the porous linear low-density polyethylene carrier resin has a porosity of 40% -60%, the ethylene-1-octene copolymer elastomer has an octene mass content of 25%, a crystallinity of 15%, the high-vinyl liquid polybutadiene has a number average molecular weight of 2000, and a 1, 2-vinyl structure mass content of 70%.
  5. 5. The crosslinked polyethylene insulated wire with the low-temperature frost crack prevention function according to claim 1, wherein the preparation method of the porous linear low-density polyethylene carrier resin comprises the following steps: Adding linear low-density polyethylene and liquid paraffin into a closed reaction kettle according to the mass ratio of 1:0.67-1:1.5, carrying out heat preservation and stirring at 180-200 ℃ to form a homogeneous solution, then cooling to 25 ℃ at the cooling rate of 5-10 ℃ per minute to enable the homogeneous solution to be subjected to thermal phase separation and solidification, deep-cooling and crushing the solidified material into particles, then placing the particles into a normal hexane solvent for ultrasonic extraction to remove the liquid paraffin in the particles, and finally drying under the vacuum condition to obtain the porous linear low-density polyethylene carrier resin.
  6. 6. The crosslinked polyethylene insulated wire with the low-temperature frost crack prevention function according to claim 1, wherein the insulating layer is prepared from the following raw materials, by weight, 70.0 parts of linear low-density polyethylene, 20.0 parts of ethylene-1-octene copolymer elastomer, 10.0 parts of porous linear low-density polyethylene carrier resin, 0.05 parts of fluorine-containing polymer processing aid and 6.30 parts of homogeneous active mixed solution; the porous linear low-density polyethylene carrier resin is mixed with the homogeneous phase active mixed solution in advance and adsorbed to prepare a dry silane master batch, and then the dry silane master batch is extruded and molded; The homogeneously active mixture comprises 2.0 parts by weight of vinyltris (2-methoxyethoxy) silane, 0.6 parts by weight of 1-octadecene, 3.5 parts by weight of high vinyl liquid polybutadiene, 0.10 parts by weight of tert-butyl peroxybenzoate, 0.05 parts by weight of 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane and 0.05 parts by weight of dibutyltin dilaurate.
  7. 7. A method for preparing the crosslinked polyethylene insulated wire with the low-temperature frost crack prevention function according to any one of claims 1 to 6, comprising the following steps: S1, mixing a set weight part of vinyl tri (2-methoxyethoxy) silane, 1-octadecene, high vinyl liquid polybutadiene, a first-stage initiator, a second-stage initiator and a silane crosslinking catalyst, and stirring to form a homogeneous phase active mixed solution; S2, putting the porous linear low-density polyethylene carrier resin into a high-speed mixer, spraying the homogeneously active mixed liquid and continuously stirring to enable the homogeneously active mixed liquid to be absorbed into micropores of the porous linear low-density polyethylene carrier resin, so as to obtain a dry silane master batch; S3, adding the linear low-density polyethylene, the ethylene-1-octene copolymer elastomer, the fluorine-containing polymer processing aid and the dry silane master batch into a homodromous double-screw extruder with a plurality of temperature control sections together for melting, grafting reaction and three-dimensional network anchoring; S4, enabling the melt homogenized by the homodromous double-screw extruder to enter an extrusion cross head and uniformly coat the outer layer of the metal conductor, cooling and solidifying, and then sending into a warm water or steam environment for treatment to complete crosslinking, so as to obtain the crosslinked polyethylene insulated wire with the low-temperature frost crack prevention function.
  8. 8. The preparation method of the cross-linked polyethylene insulated wire with the low-temperature frost-crack prevention function, which is characterized by comprising the steps of controlling the mixing temperature to be 30-50 ℃ and the stirring time to be 10-15 min in the step S1, maintaining the temperature in a high-speed mixer to be 50-60 ℃ and setting the stirring rotating speed to be 200-300 rpm and the stirring time to be 20-40 min in the step S2.
  9. 9. The method for preparing the crosslinked polyethylene insulated wire with the low-temperature frost crack prevention function according to claim 7, wherein the specific implementation manner of the step S3 is as follows: the inside of the homodromous double-screw extruder is sequentially divided into a melting zone, a grafting reaction zone and a network anchoring zone from the feeding direction to the discharging direction, wherein the process parameters of each temperature zone of the homodromous double-screw extruder are that the temperature of a machine barrel of the melting zone is set to 120-140 ℃, the temperature of the machine barrel of the grafting reaction zone is set to 165-175 ℃, and the temperature of the machine barrel of the network anchoring zone is set to 195-210 ℃; In order to construct a melt sealing environment of a high-pressure inhibition air hole, a first flow blocking ring element is assembled on a screw configuration at the tail end of a melting zone, a second flow blocking ring element is assembled at the tail end of a grafting reaction zone, and the residence time of materials in a closed grafting reaction space formed by the first flow blocking ring element and the second flow blocking ring element is strictly controlled to be 15-25 s.
  10. 10. The preparation method of the crosslinked polyethylene insulated wire with the low-temperature frost-crack prevention function according to claim 7, wherein in the step S4, the temperature of the extrusion cross head is set to be 200-210 ℃, the cooling and curing are carried out after the extrusion cross head is uniformly coated on the outer layer of a metal conductor and then the extrusion cross head enters a water tank at 25 ℃, and the process parameters of the treatment and the crosslinking are that the treatment is carried out in a constant-temperature water tank at 80-95 ℃ or a steam crosslinking room at 100 ℃ for 4-8 hours.

Description

Crosslinked polyethylene insulated wire with low-temperature frost crack prevention function Technical Field The invention relates to the technical field of wire and cable manufacturing, in particular to a crosslinked polyethylene insulated wire with a low-temperature frost crack prevention function. Background The crosslinked polyethylene insulated wire has good electrical insulation performance and high current-carrying capacity, and is widely applied to electric laying of buildings and power transmission and distribution engineering of power grids. The conventional crosslinked polyethylene material has stable physical and mechanical properties at normal temperature and high temperature, but in extremely cold environment, the motion capability of a polymer molecular chain segment is sharply weakened, and the local crystallinity of the material is relatively increased and is in a hardened state. When the cable is bent, laid and pulled or subjected to external mechanical impact under the low-temperature weather, the insulating layer is extremely easy to embrittle and crack, so that electrical accidents such as electric leakage or short circuit are caused. In order to improve the low temperature resistance of crosslinked polyethylene, it is common practice in the prior art to add small molecular plasticizers to the matrix resin or to blend polyolefin elastomers having low glass transition temperatures in large amounts. Although the treatment mode can relieve the low-temperature brittleness of the insulating layer to a certain extent, the comprehensive heat engine performance of the material is damaged. The addition of a large amount of elastomer dilutes the crosslinkable sites in the matrix resin, resulting in a decrease in the overall crosslinking degree of the insulating layer, and thus a deterioration in creep resistance of the cable in an overload heating state, and a thermal elongation exceeding the standard requirements. Meanwhile, the micromolecular plasticizer is easy to migrate and exude outwards in the long-term temperature alternating operation of the electric wire, so that the cold-resistant effect is attenuated with time. In addition, in the conventional silane crosslinking process, the crosslinking agent in a liquid state and the modifying monomer are generally directly attached to the surface of the resin particles by mechanical stirring. These free liquid components are subject to premature volatilization by heating during subsequent extruder feeding and melting. This not only leads to a mismatch in the ratios actually involved in the grafting reaction, but also leaves a large number of foamed micropores inside the insulating layer due to vaporization of the polar small molecules. These microscopic voids disrupt the compactness of the insulating layer and provide microscopic migration channels for free moisture and polar impurities, ultimately leading to an increase in the dielectric loss tangent of the wire, severely affecting the stability and service life of high voltage transmission. Therefore, the invention provides a crosslinked polyethylene insulated wire with a low-temperature frost crack prevention function, which solves the defects in the prior art. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a crosslinked polyethylene insulated wire with a low-temperature frost crack prevention function, which solves the problems that an insulating layer of the conventional crosslinked polyethylene insulated wire is easy to harden and brittle fracture in an extremely cold environment, and the conventional plasticization modification can cause the reduction of crosslinking degree and the increase of dielectric loss. In order to solve the problems, the invention provides the following technical scheme: In a first aspect, the invention provides a crosslinked polyethylene insulated wire with a low-temperature frost crack prevention function, which adopts the following technical scheme: The crosslinked polyethylene insulated wire with the low-temperature frost crack prevention function is characterized in that the insulating layer is prepared from the following raw materials in parts by weight: 55.0-82.0 parts by weight of linear low density polyethylene; 10.0-30.0 parts by weight of an ethylene-1-octene copolymer elastomer; 8.0-15.0 parts by weight of porous linear low-density polyethylene carrier resin; 0.02-0.10 parts by weight of a fluorine-containing polymer processing aid; 3.29-9.31 parts by weight of homogeneous phase active mixed solution; the porous linear low-density polyethylene carrier resin is mixed with the homogeneous phase active mixed solution in advance and adsorbed to prepare a dry silane master batch, and then the dry silane master batch is extruded and molded; The homogeneously active mixed solution comprises: 1.0-3.0 parts by weight of vinyl tri (2-methoxyethoxy) silane; 0.2-1.0 part by weight of 1-octadecene; 2.0-5.0 parts by weight of hi