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CN-121991425-A - Modified polyethylene foam material and preparation method thereof

CN121991425ACN 121991425 ACN121991425 ACN 121991425ACN-121991425-A

Abstract

The invention relates to the technical field of foaming materials, in particular to a modified polyethylene foaming material and a preparation method thereof, wherein the modified polyethylene foaming material comprises the following components: polyethylene matrix, modified silica aerogel, LDH@polyethylene-maleic anhydride, hydroxyapatite@stearic acid, a foaming agent, a crosslinking agent and an antioxidant. When a fire disaster occurs, LDH is heated and decomposed to form a first protective barrier to prevent molten polyethylene liquid from penetrating into the pore canal in a capillary way, and the decomposed alkaline oxide consumes redundant H + in the system. The inorganic network of aluminophosphate and the organic polymer generated by ZnCl 2 /FeCl 3 are catalyzed to form an organic-inorganic hybridization blocking layer, so that a second protective barrier is formed, the organic layer flexibly fills the pore gap, and the inorganic layer provides high-temperature stability. Stearic acid is coordinated with ZnCl 2 /FeCl 3 acid preferentially and is stable at the processing temperature of the foaming agent, so that the stearic acid can not act with the foaming agent and PE chains any more, and the foaming quality is ensured.

Inventors

  • LIANG YAJIANG
  • LI XIAOHONG
  • CHEN JINGXIONG

Assignees

  • 宁波久禾新材料有限公司

Dates

Publication Date
20260508
Application Date
20260320

Claims (7)

  1. 1. The modified polyethylene foam material is characterized by comprising, by weight, 80-100 parts of a polyethylene matrix, 10-30 parts of modified silica aerogel, 5-15 parts of LDH@polyethylene-maleic anhydride, 3-10 parts of hydroxyapatite@stearic acid, 2-5 parts of a foaming agent, 0.3-0.8 part of a cross-linking agent and 0.2-0.5 part of an antioxidant; the modified silica aerogel pore canal is loaded with ZnCl 2 /FeCl 3 catalyst and is filled with aluminum phosphate precursor; the LDH@polyethylene-maleic anhydride is of a core-shell structure, the LDH is taken as a core, and the polyethylene-maleic anhydride is taken as a shell; the hydroxyapatite@stearic acid is of a core-shell structure, the hydroxyapatite is used as a core, and the stearic acid is used as a shell.
  2. 2. The modified polyethylene foam material according to claim 1, wherein the preparation method of the modified silica aerogel comprises the following steps: s11, ultrasonically dispersing the silicon dioxide aerogel in an ethanol/deionized water mixed solution, refluxing and stirring under the protection of water bath and nitrogen, filtering the obtained reaction liquid, collecting solids, and vacuum drying to obtain activated silicon dioxide aerogel; s12, stirring ZnCl 2 and FeCl 3 , dissolving in absolute ethyl alcohol, adding activated silica aerogel, carrying out ultrasonic impregnation and rotary evaporation, and transferring the obtained solid into a tube furnace for calcination to obtain metal-loaded aerogel; S13, stirring and dissolving Al (H 2 PO 4 ) 3 ) in deionized water, adding metal loaded aerogel, stirring and soaking, slowly adjusting pH with ammonia water, filtering and collecting solid, washing with deionized water, and vacuum drying to obtain the modified silica aerogel.
  3. 3. The modified polyethylene foam material according to claim 1, wherein the preparation method of the LDH@polyethylene-maleic anhydride comprises the following steps: S21, dissolving Mg (NO 3 ) 2 ·6H 2 O and Al (NO 3 ) 3 ·9H 2 O in deionized water to obtain a solution A, dissolving NaOH and Na 2 CO 3 in deionized water to obtain a solution B, simultaneously dropwise adding the solution A and the solution B into the deionized water under the protection of nitrogen, crystallizing, aging, filtering, collecting solids, washing with the deionized water, vacuum drying, grinding and sieving to obtain LDH powder; S22, stirring and dissolving maleic anhydride and dicumyl peroxide in acetone to obtain a solution C, uniformly spraying the solution C on the surfaces of low-density polyethylene particles, stirring and soaking, standing in an open way, adding an antioxidant 1010, stirring uniformly, adding the obtained mixture into a double-screw extruder, performing melt grafting reaction, water-cooling to form strips after extrusion, granulating, purifying by a Soxhlet extractor, and performing vacuum drying to obtain polyethylene-maleic anhydride; S23, stirring and dissolving polyethylene-maleic anhydride in dimethylbenzene, adding LDH powder, stirring and dispersing under heating, performing ultrasonic treatment, slowly cooling to room temperature, separating out crystals of the polyethylene-maleic anhydride on the surface of the LDH powder, filtering and collecting solids, washing with dimethylbenzene, and performing vacuum drying to obtain the LDH@polyethylene-maleic anhydride.
  4. 4. The modified polyethylene foam material according to claim 3, wherein the temperature of a first zone of the twin-screw extruder is 140 ℃, the temperature of a second zone is 170 ℃, the temperature of a third zone is 180 ℃, the temperatures of a fourth zone and a fifth zone are 185 ℃, the temperature of a machine head is 180 ℃, the rotating speed of a screw is 100rpm, and the feeding rate is 8-10 kg/h.
  5. 5. The modified polyethylene foam material according to claim 1, wherein the preparation method of the hydroxyapatite @ stearic acid comprises the following steps: S31, dissolving Ca (NO 3 ) 2 ·4H 2 O) in deionized water to obtain a calcium solution, dissolving Na 2 HPO 4 ·10H 2 O in deionized water to obtain a phosphorus solution, slowly dripping the phosphorus solution into the calcium solution at room temperature under stirring, maintaining pH with ammonia water, aging in water bath to promote crystallization, filtering and collecting solids, washing with deionized water, vacuum drying, and grinding to obtain nano hydroxyapatite; s32, stirring stearic acid to dissolve in absolute ethyl alcohol, adding nano hydroxyapatite, performing ultrasonic dispersion, continuously stirring, filtering and collecting solid, washing with cold ethanol, and performing vacuum drying to obtain the hydroxyapatite@stearic acid.
  6. 6. A method for preparing a modified polyethylene foam material, which is applied to preparing the modified polyethylene foam material according to any one of claims 1 to 5, and is characterized by comprising the following steps: s1, premixing, namely placing modified silicon dioxide aerogel and hydroxyapatite@stearic acid into a high-speed mixer, and dry-mixing uniformly to obtain a first mixture; S2, blending and granulating, namely premixing a polyethylene matrix, a first mixture and an antioxidant in a double-screw extruder to obtain a second mixture, adding LDH@polyethylene-maleic anhydride into the second mixture, and carrying out dispersion mixing to obtain a third mixture; S3, foaming and forming, namely placing the modified polyethylene composite particles into a flat vulcanizing machine, preserving heat and pressure for 25 minutes at 190 ℃ and 12MPa, performing compression molding foaming and forming, rapidly releasing pressure, demolding and cooling to obtain the modified polyethylene foaming material.
  7. 7. The preparation method of the modified polyethylene foam material according to claim 6, wherein in the blending granulation, a polyethylene matrix, a first mixture and an antioxidant are added from a main feeding port, heated and dispersed in one region to three regions at 120-165 ℃, stay for 2min, LDH@polyethylene-maleic anhydride is added from a first side feeding port, heated and dispersed in four regions to five regions at 170 ℃ and stay for 1.5min, a foaming agent and a crosslinking agent are added from a second side feeding port, heated and dispersed in six regions to a machine head at 160-165 ℃ and stay for 1min.

Description

Modified polyethylene foam material and preparation method thereof Technical Field The invention belongs to the technical field of foaming materials, and particularly relates to a modified polyethylene foaming material and a preparation method thereof. Background Polyethylene (PE) foaming materials are widely applied to the fields of building heat preservation, pipeline heat insulation, cold chain logistics packaging and the like due to light weight and excellent heat insulation and buffering performance. The silica aerogel with low heat conductivity coefficient is introduced into a PE foaming system, so that the heat insulation performance of the material can be further greatly improved, and the silica aerogel is a research hot spot in academia and industry in recent years. However, aerogel itself is not flammable, but PE as the continuous phase is flammable, and if a fire breaks out, the melted PE may become entrapped with the dripping of aerogel powder, not only failing to form an effective fire barrier, but may even promote fire spread due to the "wick effect". On one hand, when a fire disaster happens, PE is heated to melt, a developed nano pore network in the silica aerogel has extremely strong capillary adsorption force on molten PE liquid, the molten PE liquid is accumulated in the pore to form a fuel reservoir, on the other hand, the huge specific surface area of the aerogel has catalytic acceleration on PE pyrolysis, PE adsorbed in the pore is quickly pyrolyzed to generate a large amount of combustible micromolecular gases such as alkane, alkene and the like, the combustible micromolecular gases are sprayed out to the outer surface of the material through a porous channel, the aerogel has extremely low heat conductivity coefficient to enable heat to be highly retained in the material, the inner PE is continuously pyrolyzed and continuously supplies gaseous fuel to flame to form continuous and stable flame on the surface of the material, meanwhile, the aerogel framework locks the molten PE in a core area of a fire scene to prevent the molten PE from taking away heat, the contact area of combustible matters and oxygen is greatly increased, the combustion is more durable and thorough than that of pure PE, and the fire spreading risk is remarkably increased. Disclosure of Invention (1) Technical problem to be solved The invention aims to provide a modified polyethylene foaming material and a preparation method thereof, which are used for solving the problem that the silicon dioxide aerogel modified polyethylene foaming material generates a candlewick effect when a fire disaster occurs. (2) Technical proposal In order to achieve the aim, on the one hand, the invention provides a modified polyethylene foaming material which comprises, by weight, 80-100 parts of a polyethylene matrix, 10-30 parts of modified silica aerogel, 5-15 parts of LDH@polyethylene-maleic anhydride, 3-10 parts of hydroxyapatite@stearic acid, 2-5 parts of a foaming agent, 0.3-0.8 part of a cross-linking agent and 0.2-0.5 part of an antioxidant; the modified silica aerogel pore canal is loaded with ZnCl 2/FeCl3 catalyst and is filled with aluminum phosphate precursor; the LDH@polyethylene-maleic anhydride is of a core-shell structure, the LDH is taken as a core, and the polyethylene-maleic anhydride is taken as a shell; the hydroxyapatite@stearic acid is of a core-shell structure, the hydroxyapatite is used as a core, and the stearic acid is used as a shell. Further, the preparation method of the modified silica aerogel comprises the following steps: s11, ultrasonically dispersing the silicon dioxide aerogel in an ethanol/deionized water mixed solution, refluxing and stirring under the protection of water bath and nitrogen, filtering the obtained reaction liquid, collecting solids, and vacuum drying to obtain activated silicon dioxide aerogel; s12, stirring ZnCl 2 and FeCl 3, dissolving in absolute ethyl alcohol, adding activated silica aerogel, carrying out ultrasonic impregnation and rotary evaporation, and transferring the obtained solid into a tube furnace for calcination to obtain metal-loaded aerogel; S13, stirring and dissolving Al (H 2PO4)3) in deionized water, adding metal loaded aerogel, stirring and soaking, slowly adjusting pH with ammonia water, filtering and collecting solid, washing with deionized water, and vacuum drying to obtain the modified silica aerogel. Further, the preparation method of the LDH@polyethylene-maleic anhydride comprises the following steps: S21, dissolving Mg (NO 3)2·6H2 O and Al (NO 3)3·9H2 O in deionized water to obtain a solution A, dissolving NaOH and Na 2CO3 in deionized water to obtain a solution B, simultaneously dropwise adding the solution A and the solution B into the deionized water under the protection of nitrogen, crystallizing, aging, filtering, collecting solids, washing with the deionized water, vacuum drying, grinding and sieving to obtain LDH powder; S22, stirring and dissolving