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CN-122011553-A - Ageing-resistant polyethylene composite material for electric smelting pipe fitting and preparation method thereof

CN122011553ACN 122011553 ACN122011553 ACN 122011553ACN-122011553-A

Abstract

The invention discloses an anti-aging polyethylene composite material for an electric melting pipe fitting and a preparation method thereof, which belong to the technical field of polyethylene composite materials, wherein an amide bond-containing polymerizable antioxidant monomer is synthesized through acyl chlorination and nucleophilic substitution reaction, the chlorine corrosion resistance of an antioxidant is improved on a molecular structure, meanwhile, acrylic acid and sodium dodecyl sulfate are utilized to carry out hydrophobic and double bond functional modification on hydrotalcite to obtain double bond-containing hydrophobic modified hydrotalcite, then the antioxidant monomer and hydrotalcite are chemically combined through free radical polymerization to construct a hydrotalcite-based macromolecule antioxidant, and finally the hydrotalcite-based macromolecule antioxidant and high-density polyethylene are fused and blended to prepare the composite material, so that the problems of thermal volatilization of an antioxidant component at high temperature under electric melting welding and physical migration and chemical consumption under long-term chlorine-containing water flushing are solved, and the electric melting pipe fitting is ensured to have excellent mechanical stability and long-term service life under severe service environment.

Inventors

  • Yi Shucheng
  • WANG ZHIYUE

Assignees

  • 安徽万大管业科技有限公司

Dates

Publication Date
20260512
Application Date
20260306

Claims (10)

  1. 1. The preparation method of the ageing-resistant polyethylene composite material for the electric melting pipe fitting is characterized by comprising the following steps of: step one, using thionyl chloride as an acyl chloride reagent, activating carboxyl of 3, 5-di-tert-butyl-4-hydroxy benzene propionic acid to obtain an active acylated intermediate, and then carrying out nucleophilic substitution reaction on the active acylated intermediate and 4-amino styrene to form an amide bond, so as to obtain a polymerizable amide-group-containing antioxidant monomer; Step two, sodium dodecyl sulfonate containing long chain alkyl and acrylic acid containing reactive double bond are subjected to ion exchange and enter an interlayer structure of hydrotalcite to obtain double bond-containing hydrophobic modified hydrotalcite, and then azo diisobutyronitrile is used as an initiator to enable polymerizable amide antioxidant monomer and double bond-containing hydrophobic modified hydrotalcite to undergo in-situ free radical graft polymerization reaction to obtain hydrotalcite-based macromolecular antioxidant; and thirdly, taking high-density polyethylene as a matrix, mixing with hydrotalcite-based macromolecular antioxidant and polyethylene wax, and carrying out melt extrusion and granulation in a double-screw extruder to obtain the ageing-resistant polyethylene composite material for the electric melting pipe fitting.
  2. 2. The method for preparing an aging-resistant polyethylene composite material for electric melting pipes according to claim 1, wherein the hydrotalcite-based macromolecular antioxidant in the second step is prepared by the steps of: placing double bond-containing hydrophobic modified hydrotalcite and toluene in a reaction kettle under the protection of nitrogen atmosphere, stirring for 10-20min at 25-35 ℃, adding polymerizable amide-containing antioxidant monomer and azodiisobutyronitrile, reacting for 6-8h at 70-80 ℃, filtering, washing, and vacuum drying to constant weight to obtain the hydrotalcite-based macromolecular antioxidant.
  3. 3. The method for preparing the aging-resistant polyethylene composite material for the electric melting pipe fitting, according to claim 2, wherein the dosage ratio of the double bond-containing hydrophobically modified hydrotalcite, the polymerizable amide-containing antioxidant monomer, the azodiisobutyronitrile and the toluene is 40-60 g/15-20 g/0.2-0.4 g/300-500 mL.
  4. 4. The method for preparing an aging-resistant polyethylene composite material for electric-melting pipes according to claim 3, wherein the double bond-containing hydrophobically modified hydrotalcite is prepared by the steps of: and (3) placing hydrotalcite, sodium dodecyl sulfonate, acrylic acid and deionized water into a reaction kettle, stirring for 20-40min at 25-35 ℃, adding a nitric acid solution with the concentration of 0.1mol/L to adjust the pH value of the reaction solution to 5-6, reacting for 2-4h at 60-80 ℃, filtering, washing, vacuum drying to constant weight, grinding and screening to obtain the double bond-containing hydrophobic modified hydrotalcite.
  5. 5. The method for preparing an aging-resistant polyethylene composite material for electric melting pipes according to claim 4, wherein the dosage ratio of hydrotalcite to sodium dodecyl sulfate to acrylic acid to deionized water is 50-70 g/6-8 g/10-14 g/600-800 mL.
  6. 6. A method for preparing an aging-resistant polyethylene composite material for electric-melting pipes according to claim 3, wherein said polymerizable amide-group-containing antioxidant monomer is prepared by the steps of: Placing 4-aminostyrene, N-diisopropylethylamine and methylene dichloride into a reaction kettle, stirring for 10-20min at 25-35 ℃, cooling to 0-5 ℃, adding an active acylation intermediate, heating to 25-35 ℃ for reacting for 2-4h, extracting and washing a reaction liquid, collecting a lower methylene dichloride organic phase, adding anhydrous magnesium sulfate for drying, filtering for removing impurities, and steaming until a solvent is completely removed, thereby obtaining a polymerizable amide-containing antioxidant monomer; The dosage ratio of the 4-aminostyrene, the N, N-diisopropylethylamine, the active acylated intermediate and the dichloromethane is 10-20g to 20-40g to 30-50g to 300-500mL.
  7. 7. The method for preparing an aging-resistant polyethylene composite material for electric-melting pipes according to claim 6, wherein the preparation process of the active acylated intermediate is as follows: Placing 3, 5-di-tert-butyl-4-hydroxy benzene propionic acid and methylene dichloride in a reaction kettle under the protection of nitrogen atmosphere, stirring for 20-40min at 25-35 ℃, adding thionyl chloride, reacting for 4-6h at 40-60 ℃, and distilling under reduced pressure to obtain an active acylated intermediate; the dosage ratio of the 3, 5-di-tert-butyl-4-hydroxy phenylpropionic acid, thionyl chloride and dichloromethane is 50-100g:40-60g:200-300mL.
  8. 8. The method for preparing an aging-resistant polyethylene composite material for electric melting pipes according to claim 1, wherein in the third step, the mass ratio of the high-density polyethylene, the hydrotalcite-based macromolecule antioxidant and the polyethylene wax is 300-500:10-20:3-5.
  9. 9. The method for preparing an aging-resistant polyethylene composite material for electric-melting pipes according to claim 1, wherein in the third step, the processing temperature of the twin-screw extruder in the temperature region is 160-170 ℃, 180-200 ℃ and 190-210 ℃ respectively, the die temperature is 190-210 ℃ and the screw rotating speed is 200-300r/min.
  10. 10. An aging-resistant polyethylene composite material for electric melting pipe fittings, characterized in that it is prepared by a method for preparing an aging-resistant polyethylene composite material for electric melting pipe fittings as claimed in any one of claims 1 to 9.

Description

Ageing-resistant polyethylene composite material for electric smelting pipe fitting and preparation method thereof Technical Field The invention belongs to the technical field of polyethylene composite materials, and particularly relates to an aging-resistant polyethylene composite material for an electric melting pipe fitting and a preparation method thereof. Background Polyethylene pipes have been widely used in urban water supply pipe network systems by virtue of their excellent toughness and connection reliability, wherein an electric melting pipe is used as a special connecting piece with embedded resistance wires, and the working principle is that polyethylene resin on the inner wall of the pipe and the outer wall of the pipe is melted at high temperature by electric heating to form an integrated connection interface, which means that the electric melting pipe is not only in direct contact with tap water medium for a long time, but also must be subjected to severe high-temperature hot-oxygen impact at the initial stage of installation. In order to improve the thermo-oxidative aging resistance of polyethylene materials, the current industry common practice is to add antioxidants to the polyethylene matrix to form an anti-aging system. In the prior art scheme, chinese patent application with publication number of CN110467769A discloses an antioxidation high-density polyethylene composite material and a preparation method thereof, and the antioxidation performance of the material is improved by compounding a phenolic antioxidant 1010 and a phosphite antioxidant 168 to form a micromolecular composite antioxidation system and adding a synergistic inorganic filler into a high-density polyethylene matrix in a physical mixing mode. In the technical scheme, as the molecular weight of the antioxidant is low and the antioxidant is dispersed in the matrix only through physical action, the binding force with the matrix is weak, the micromolecular antioxidant obtains extremely high thermal motion energy under the action of a high-temperature thermal field of electric melting welding, the intermolecular acting force is extremely easy to overcome, severe thermal migration and volatilization occur to the surface of a melt, the irreversible physical migration easily causes loss of antioxidant components at a key welding interface, oxidation fracture and degradation of a polyethylene molecular chain which is lost easily occur under the attack of thermal oxygen, the pipe fitting material is easy to become brittle and the strength is greatly reduced in the use process, and the requirement of long-term safe service of the electric melting pipe fitting is difficult to meet. Disclosure of Invention The invention aims to provide an ageing-resistant polyethylene composite material for an electric melting pipe fitting and a preparation method thereof, and an antioxidant monomer is fixedly supported on a hydrotalcite carrier in a chemical bonding mode, so that in-situ anchoring and chemical stabilization of an antioxidant component in a high-temperature welding thermal field and chlorine-containing water flow environment are realized, and the long-acting ageing resistance of the material is improved. The aim of the invention can be achieved by the following technical scheme: The invention provides an aging-resistant polyethylene composite material for an electric melting pipe fitting, which is prepared by the following steps: step one, using thionyl chloride as an acyl chloride reagent, activating carboxyl of 3, 5-di-tert-butyl-4-hydroxy benzene propionic acid to obtain an active acylated intermediate, and then carrying out nucleophilic substitution reaction on the active acylated intermediate and 4-amino styrene to form an amide bond, so as to obtain a polymerizable amide-group-containing antioxidant monomer; Step two, sodium dodecyl sulfonate containing long chain alkyl and acrylic acid containing reactive double bond are subjected to ion exchange and enter an interlayer structure of hydrotalcite to obtain double bond-containing hydrophobic modified hydrotalcite, and then azo diisobutyronitrile is used as an initiator to enable polymerizable amide antioxidant monomer and double bond-containing hydrophobic modified hydrotalcite to undergo in-situ free radical graft polymerization reaction to obtain hydrotalcite-based macromolecular antioxidant; and thirdly, taking high-density polyethylene as a matrix, mixing with hydrotalcite-based macromolecular antioxidant and polyethylene wax, and carrying out melt extrusion and granulation in a double-screw extruder to obtain the ageing-resistant polyethylene composite material for the electric melting pipe fitting. The invention also provides a preparation method of the ageing-resistant polyethylene composite material for the electric melting pipe fitting, which comprises the following steps: placing high-density polyethylene, hydrotalcite-based macromolecular antioxidant and polyethylene