Multilayer copolymerized foaming material, preparation method and application

Abstract

The invention provides a multi-layer copolymerized foaming material, a preparation method and application, and belongs to the field of rubber and plastic foaming thermal insulation materials. According to the invention, the insulating layer rubber sheet is firstly stood at 110-130 DEG C for 4-6 minutes, and the high-acrylonitrile nitrile rubber is preferentially vulcanized to form a low-density elastic framework; according to the present invention, the POE-g-MAH and PVC are subjected to standing for 7-10 min at the temperature of 145-155 DEG C, PVC plasticizing and foaming are synchronously performed, the POE-g-MAH and PVC coupling and interface bonding energy can be improved within the temperature range, and finally the POE-g-MAH and PVC are subjected to standing for 2-4 min at the temperature of 155-165 DEG C so as to reinforce cross-linking and crystallization, such that the tensile strength of the material is improved, and the tensile strength is improved from less than 4.5 MPa in the conventional process to more than 6.0 MPa. The thermal bridge effect is reduced by reducing phase interface defects, so that the overall heat conductivity coefficient is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of rubber-plastic foam insulation materials, and in particular relates to a multi-layer copolymer foam material, a preparation method and an application thereof. Background Art

[0002] Due to their excellent thermal insulation, sound insulation, and shock absorption properties, rubber-plastic foam materials have been widely used in many fields such as cold chain logistics, building insulation, and the automotive industry. However, rubber-plastic foam materials have serious deficiencies in the synergy of multi-phase and multi-scale structures, which has caused the industry to face a long-term dilemma of balancing mechanical properties and thermal insulation properties. The rubber-plastic blend system, represented by NBR (rubber phase) and PVC (plastic phase), is prone to phase separation during the blending process due to the significant difference in polarity between the two. This phenomenon directly leads to extremely weak interfacial bonding between the two phases, and the tensile strength of the material is usually difficult to exceed 4.5MPa. In actual application scenarios, when faced with large external forces, the material is prone to tensile fracture.

[0003] Traditional solutions are often limited to using physical compatibilizers like chlorinated polyethylene (CPE) to improve the interfacial compatibility between NBR and PVC. However, while the addition of physical compatibilizers like CPE improves interfacial bonding to a certain extent, it also reduces the material's flexibility and impairs its foaming properties. Therefore, developing a technical solution that can effectively address the synergistic effects of multiphase and multiscale structures in rubber-plastic foam materials while also improving mechanical and thermal insulation properties has become a key technical challenge that needs to be overcome in the field of rubber-plastic foam materials. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention aims to provide a multi-layer copolymer foam material, a preparation method and an application thereof.

[0005] One of the purposes of the present invention is to provide a multi-layer copolymer foam material, which includes a thermal insulation layer, wherein the raw materials of the thermal insulation layer include high acrylonitrile butadiene rubber, aerogel powder, sodium bicarbonate, AC foaming agent, vulcanizing agent, accelerator, co-crosslinking agent, plasticizer, PVC and maleic anhydride grafted ethylene-octene copolymer (POE-g-MAH); The preparation method of the multi-layer copolymer foam material comprises the following steps: The raw materials of the thermal insulation layer are mixed evenly and sheeted to obtain a thermal insulation layer film; The thermal insulation layer film is first allowed to stand at 110-130° C. for 4-6 minutes, then allowed to stand at 145-155° C. for 7-10 minutes, and then allowed to stand at 155-165° C. for 2-4 minutes for vulcanization and foaming, and finally cooled and formed to obtain the multi-layer copolymer foam material.

[0006] Preferably, the raw materials of the thermal insulation layer are mixed evenly and sheeted to obtain the thermal insulation layer film, which comprises the following steps: Preheating the high acrylonitrile butadiene rubber at a temperature of 60-70° C. for 10-15 minutes; Add the preheated high acrylonitrile butadiene rubber, sodium bicarbonate, AC foaming agent, vulcanizing agent, accelerator, co-crosslinking agent, plasticizer, PVC and POE-g-MAH into a high-speed mixer and stir at a speed of 800-1000 rpm for 10-15 minutes; Finally, aerogel powder is added, and the mixture is stirred at a speed of 600 rpm for 5 to 10 minutes before being discharged to obtain a thermal insulation layer film.

[0007] Preferably, the multilayer copolymer foam material further comprises a protective layer, and the raw materials of the protective layer include EPDM rubber, calcium stearate, POE-g-MAH, precipitated silica, ultraviolet absorber, antioxidant, plasticizer, flame retardant, AC foaming agent, vulcanizer and accelerator.

[0008] Preferably, the ultraviolet absorber includes UV-531, the antioxidant includes antioxidant 1010, the plasticizer includes dioctyl phthalate, and the flame retardant includes aluminum hydroxide.

[0009] Preferably, the multi-layer copolymer foam material further includes a low-temperature adaptation layer, and the raw materials of the low-temperature adaptation layer further include hydrogenated nitrile rubber, PVC, ethylene-vinyl acetate copolymer, ethylene glycol ether, silane coupling agent, diisopropylbenzene peroxide, diisononyl phthalate, dinitrosopentamethylenetetramine and POE-g-MAH; the mass ratio of the hydrogenated nitrile rubber to PVC is 6~7:2~3.

[0010] Preferably, the thermal insulation layer is located between the protective layer and the low-temperature adaptation layer; the protective layer, the thermal insulation layer and the low-temperature adaptation layer are an integral structure, and are integrally formed by co-extrusion and vulcanization foaming.

[0011] A second object of the present invention is to provide a method for preparing a multilayer copolymer foam material, comprising the following steps: The raw materials of the protective layer are mixed evenly and sheeted to obtain a protective layer film; The raw materials of the thermal insulation layer are mixed evenly and sheeted to obtain a thermal insulation layer film; The raw materials of the low temperature adaptation layer are mixed evenly and sheeted to obtain a low temperature adaptation layer film; The protective layer film, the thermal insulation layer film and the low temperature adaptation layer film are blended and extruded to obtain a mixed film; The mixed film is first allowed to stand at 110-130° C. for 4-6 minutes, then allowed to stand at 145-155° C. for 7-10 minutes, then allowed to stand at 155-165° C. for 2-4 minutes for vulcanization and foaming, and finally cooled and formed to obtain the multilayer copolymer foam material.

[0012] Preferably, the raw materials for the protective layer are mixed evenly and produced into a sheet to obtain the protective layer film, which comprises the following steps: The raw materials of the protective layer are stirred at a rotation speed of 800-1000 rpm for 15-20 minutes and then produced into a sheet to obtain a protective layer film.

[0013] Preferably, the raw materials of the low-temperature adaptation layer are mixed evenly and produced to obtain the low-temperature adaptation layer film, which includes the following steps: Preheating the hydrogenated nitrile rubber at a temperature of 60-70° C. for 10-15 minutes; Pre-swell ethylene-vinyl acetate copolymer and diisononyl phthalate at 50-70°C for 30 minutes; The preheated hydrogenated nitrile rubber, pre-swollen ethylene-vinyl acetate copolymer, diisononyl phthalate, PVC, ethylene glycol ether, silane coupling agent, dicumyl peroxide, dinitrosopentamethylenetetramine and POE-g-MAH are added into a high-speed mixer, stirred at a speed of 800-1000 rpm for 15-20 minutes, and then a sheet is produced to obtain a low-temperature adaptation layer film.

[0014] A third object of the present invention is to provide an application of the multi-layer copolymer foam material as described above in cold chain insulation.

[0015] The beneficial effects of the present invention include: The insulation film of this invention is first allowed to stand at 110-130°C for 4-6 minutes. This allows the high-acrylonitrile butadiene-acrylonitrile rubber to preferentially vulcanize, forming a low-density elastic skeleton. This limits the disordered expansion of cells during the subsequent foaming process, preventing cell merging or rupture and laying the foundation for a closed-cell structure. The film is then allowed to stand at 145-155°C for 7-10 minutes, allowing the PVC to plasticize and foam simultaneously. Within this temperature range, the anhydride groups of the maleic anhydride-grafted ethylene-octene copolymer (POE-g-MAH) couple with the PVC molecular chains, forming chemical covalent bonds. This increases interfacial binding energy, allowing gas to expand uniformly within the elastic network of the rubber phase (NBR), forming a dense closed-cell structure. This reduces convective heat dissipation, and the thermal conductivity decreases as the closed-cell ratio increases.

[0016] The ethylene-octene chain segments of POE-g-MAH are both flexible and crystalline, allowing them to embed into both the NBR cross-linked network and the PVC crystalline regions, forming an interpenetrating network structure. This allows for more uniform stress transfer and prevents tensile fracture caused by interfacial defects. The chemically bonded interface and interpenetrating network structure result in more uniform stress distribution, reducing stress concentration during stretching and increasing tensile strength from <4.5 MPa achieved with conventional processes to over 6.0 MPa.

[0017] Finally, the material is allowed to stand at 155-165°C for 2-4 minutes to enhance crosslinking and crystallization. Further crosslinking of the NBR molecular chains at 155-165°C increases network density, strengthens the cell walls, and inhibits cell collapse. This promotes orderly alignment of the PVC molecular chains, enhances crystallinity, and forms rigid support points. These, in synergistically with the NBR elastic network, enhance the material's tensile strength. Increased crystallinity also reduces thermal bridging by reducing interfacial defects, ultimately lowering overall thermal conductivity. DETAILED DESCRIPTION

[0018] According to a first aspect of the present invention, a multilayer copolymer foam material is provided, the multilayer copolymer foam material comprising a thermal insulation layer, the raw materials of the thermal insulation layer comprising high acrylonitrile butadiene rubber, aerogel powder, sodium bicarbonate, AC foaming agent, vulcanizing agent, accelerator, co-crosslinking agent, plasticizer, PVC and POE-g-MAH; The preparation method of the multi-layer copolymer foam material comprises the following steps: The raw materials of the thermal insulation layer are mixed evenly and sheeted to obtain a thermal insulation layer film; The thermal insulation layer film is first allowed to stand at 110-130° C. for 4-6 minutes, then allowed to stand at 145-155° C. for 7-10 minutes, and then allowed to stand at 155-165° C. for 2-4 minutes for vulcanization and foaming, and finally cooled and formed to obtain the multi-layer copolymer foam material.

[0019] In this method, the insulation film is first allowed to stand at 110-130°C for 4-6 minutes. This allows the high-acrylonitrile butadiene-acrylonitrile rubber to preferentially vulcanize, forming a low-density elastic skeleton. This limits the disordered expansion of cells during the subsequent foaming process, preventing cell merging or rupture and laying the foundation for a closed-cell structure. The film is then allowed to stand at 145-155°C for 7-10 minutes, allowing the PVC to plasticize and foam simultaneously. Within this temperature range, the anhydride groups couple with the PVC molecular chains to form chemical covalent bonds, increasing interfacial binding energy and allowing gas to expand uniformly within the NBR elastic network, forming a dense closed-cell structure. This reduces convection heat dissipation and reduces thermal conductivity as the closed-cell ratio increases.

[0020] The ethylene-octene chain segments of POE-g-MAH are both flexible and crystalline, allowing them to embed into both the NBR cross-linked network and the PVC crystalline regions, forming an interpenetrating network structure. This allows for more uniform stress transfer and prevents tensile fracture caused by interfacial defects. The chemically bonded interface and interpenetrating network structure result in more uniform stress distribution, reducing stress concentration during stretching and increasing tensile strength from <4.5 MPa achieved with conventional processes to over 6.0 MPa.

[0021] Finally, the material is allowed to stand at 155-165°C for 2-4 minutes to enhance crosslinking and crystallization. Further crosslinking of the NBR molecular chains at 155-165°C increases network density, strengthens the cell walls, and inhibits cell collapse. This promotes orderly alignment of the PVC molecular chains, enhances crystallinity, and forms rigid support points. These, in synergistically with the NBR elastic network, enhance the material's tensile strength. Increased crystallinity also reduces thermal bridging by reducing interfacial defects, ultimately lowering overall thermal conductivity.

[0022] In a preferred embodiment of the present invention, the raw materials of the thermal insulation layer are mixed uniformly and sheeted to obtain the thermal insulation layer film, which comprises the following steps: Preheating the high acrylonitrile butadiene rubber at a temperature of 60-70° C. for 10-15 minutes; Add the preheated high acrylonitrile butadiene rubber, sodium bicarbonate, AC foaming agent, vulcanizing agent, accelerator, co-crosslinking agent, plasticizer, PVC and POE-g-MAH into a high-speed mixer and stir at a speed of 800-1000 rpm for 10-15 minutes; Finally, aerogel powder was added, and the mixture was stirred at a speed of 600 rpm for 5 to 10 minutes before being discharged to obtain a thermal insulation layer film.

[0023] In a preferred embodiment of the present invention, the multilayer copolymer foam material includes an insulation layer, which includes the following raw materials in parts by weight: 70-80 parts of high acrylonitrile-butadiene rubber, 5-10 parts of aerogel powder, 2-4 parts of sodium bicarbonate, 4-6 parts of AC foaming agent, 1-2 parts of sulfur, 0.5-1 parts of accelerator N-cyclohexyl-2-benzothiazole sulfenamide (CZ), 0.5-1 parts of co-crosslinking agent triallyl isocyanurate (TAIC), 25-35 parts of plasticizer dioctyl sebacate (DOS), 10-15 parts of PVC and 3-10 parts of POE-g-MAH.

[0024] In a preferred embodiment of the present invention, the multilayer copolymer foam material further comprises a protective layer, the raw materials of which include EPDM rubber, calcium stearate, POE-g-MAH, precipitated silica, ultraviolet absorber, antioxidant, plasticizer, flame retardant, AC foaming agent, vulcanizing agent and accelerator.

[0025] In the present invention, EPDM rubber forms a tight three-dimensional network structure through vulcanizers and accelerators, and the interaction between molecular chains is strong, which improves the overall strength and tear resistance; EPDM rubber has both a non-polar main chain and a polar third monomer, and has good compatibility with fillers, which facilitates the introduction of high-proportion reinforcing fillers. The surface of silica is rich in hydroxyl groups, and it forms a filler-rubber network with the EPDM rubber molecular chain through physical adsorption and hydrogen bonds, which significantly improves the tensile strength, tear strength and hardness. The reinforcing effect of silica is close to that of carbon black, but it has better aging resistance. Silica itself has a high density of about 2.65g / cm 3 High filler loading directly increases the overall density of the protective layer, while micro-crosslinking reduces molecular chain slip and strengthens structural density. The maleic anhydride (MAH) groups in the compatibilizer POE-g-MAH react with the double bonds of the EPDM rubber and the hydroxyl groups of silica to form a rubber-compatibilizer-filler chemical bridge. This reduces interfacial defects, improves load transfer efficiency, and avoids strength loss caused by filler agglomeration. The elastomeric segments of POE-g-MAH are embedded in the EPDM rubber network, further densifying the structure through physical entanglement and chemical crosslinking, thereby improving tear resistance.

[0026] EPDM rubber contains no easily oxidizable double bonds and exhibits significantly better ozone and weather resistance than natural rubber or nitrile rubber, making it suitable for long-term outdoor use. UV absorbers selectively absorb ultraviolet light between 280 and 400 nm, converting it into heat and preventing photooxidative breakage of the EPDM rubber backbone. Antioxidants capture free radicals, inhibiting molecular chain degradation during thermal oxidative aging and extending its service life. The synergistic protection of EPDM rubber, UV absorbers, and antioxidants enhances the material's aging resistance.

[0027] Fillers such as silica and calcium stearate fill the gaps in the rubber network, reducing free volume and further lowering the water vapor diffusion coefficient. Silica surface hydroxyl groups absorb trace amounts of water through hydrogen bonds, but the overall network is primarily composed of non-polar chains of EPDM rubber, forming a polar-non-polar interfacial barrier that inhibits liquid water penetration. Calcium stearate acts as a lubricant, migrating to the surface during processing to form a hydrophobic layer, reducing surface hygroscopicity. Its calcium salt structure also slightly inhibits hydrolysis, enhancing the material's anti-condensation properties.

[0028] Preferably, at least one surface of the multilayer copolymer foam material is provided with regularly arranged square lattice protrusions, each of which is surrounded by four mutually perpendicular strip protrusions to form a grid structure. The edges of each side of the square lattice are rounded.

[0029] In a preferred embodiment of the present invention, the ultraviolet absorber includes UV-531, the antioxidant includes antioxidant 1010, the plasticizer includes dioctyl phthalate, and the flame retardant includes aluminum hydroxide.

[0030] In a preferred embodiment of the present invention, the multi-layer copolymer foam material further includes a low-temperature adaptation layer, and the raw materials of the low-temperature adaptation layer further include hydrogenated nitrile rubber, PVC, ethylene-vinyl acetate copolymer, ethylene glycol ether, silane coupling agent, diisopropylbenzene peroxide, diisononyl phthalate, dinitrosopentamethylenetetramine and POE-g-MAH; the mass ratio of the hydrogenated nitrile rubber to PVC is 6~7:2~3.

[0031] In a preferred embodiment of the present invention, the thermal insulation layer is located between the protective layer and the low-temperature adaptation layer; the protective layer, the thermal insulation layer and the low-temperature adaptation layer are an integral structure, which are formed as one piece by co-extrusion and vulcanization foaming.

[0032] In this invention, the protective layer serves a protective function. Made from materials such as EPDM rubber, it exhibits high elasticity, weather resistance, and UV resistance. It withstands external mechanical impacts, rain, snow, and UV radiation, protecting the internal insulation layer from physical damage and environmental degradation. The protective layer's high-density precipitated silica and calcium stearate create a dense structure. Combined with the low moisture permeability of EPDM rubber, this effectively blocks moisture penetration, preventing water absorption (water has a much higher thermal conductivity than air) and maintaining long-term thermal insulation performance. Furthermore, its high moisture resistance prevents condensation from forming internally, thus avoiding the problem of condensation. This core insulation layer (intermediate layer) provides thermal insulation.

[0033] The insulation layer is primarily composed of an NBR / PVC blend, resulting in a uniform closed-cell structure through three-stage vulcanization and foaming. The internal bubbles isolate air convection, resulting in low thermal conductivity. Placed in the middle layer, it directly blocks the heat conduction path, forming a thermal barrier. The NBR rubber phase in the middle layer provides flexibility, while the PVC plastic phase enhances rigidity. The compatibilizer POE-g-MAH strengthens the interfacial bond between the two, making the insulation layer resistant to damage under load while maintaining low thermal conductivity.

[0034] The cryogenically adaptable layer, primarily composed of elastomer, maintains its elasticity even in low-temperature environments, preventing embrittlement and cracking that could expose or degrade the insulation layer. When placed in close proximity to low-temperature media, it adapts to thermal expansion and contraction, maintaining structural integrity. The elastic properties of the cryogenically adaptable layer buffer the thermal expansion differential between the pipe and the insulation layer, reducing stress concentration caused by temperature fluctuations and preventing interlayer delamination.

[0035] During the blending process, the POE-g-MAH compatibilizer in the protective layer forms chemical bonds with the PVC and NBR in the thermal insulation layer. Simultaneously, during vulcanization and foaming, the various layers diffuse into each other at the interface, forming a physically entangled network that significantly improves interlayer adhesion and prevents delamination. One-piece molding avoids the glue bonding or mechanical fixation required in traditional multi-layer composite processes, eliminating thermal bridge effects and water vapor penetration paths caused by interfacial gaps. During co-extrusion, the three layers of material are melted, vulcanized, and foamed in the same equipment. By precisely controlling the temperature-time segmentation, the protective layer achieves low or micro-foaming, forming a high-density "skin" that enhances tear resistance and moisture resistance. The thermal insulation layer has a high foaming rate and uniform closed cells to maximize thermal insulation. The low-temperature adaptive layer is moderately foamed, balancing elasticity and support. The high strength of the protective layer, the elastic skeleton of the thermal insulation layer, and the flexibility of the low-temperature adaptive layer form a gradient mechanical support, improving the overall structure's tensile strength, compression resistance, and rebound properties.

[0036] Adding maleic anhydride-grafted ethylene-octene copolymer (POE-g-MAH) to the raw materials significantly improves the compatibility between NBR (rubber phase) and PVC (plastic phase) by coupling or hydrogen bonding the highly polar maleic anhydride (MAH) groups with the PVC molecular chains. Compared to traditional physical compatibilizers (CPEs), which only improve the interface through mechanical entanglement, POE-g-MAH achieves molecular-level compatibility through chemical crosslinking, enhancing interfacial bonding and effectively suppressing phase separation.

[0037] According to a second aspect of the present invention, there is provided a method for preparing the multilayer copolymer foam material as described above, characterized in that it comprises the following steps: The raw materials of the protective layer are mixed evenly and sheeted to obtain a protective layer film; The raw materials of the thermal insulation layer are mixed evenly and sheeted to obtain a thermal insulation layer film; The raw materials of the low temperature adaptation layer are mixed evenly and sheeted to obtain a low temperature adaptation layer film; The protective layer film, the thermal insulation layer film and the low temperature adaptation layer film are blended and extruded to obtain a mixed film; The mixed film is first allowed to stand at 110-130° C. for 4-6 minutes, then allowed to stand at 145-155° C. for 7-10 minutes, then allowed to stand at 155-165° C. for 2-4 minutes for vulcanization and foaming, and finally cooled and formed to obtain the multilayer copolymer foam material.

[0038] In a preferred embodiment of the present invention, the raw materials for the protective layer are uniformly mixed and sheeted to obtain the protective layer film, which comprises the following steps: The raw materials of the protective layer are stirred at a rotation speed of 800-1000 rpm for 15-20 minutes and then produced into a sheet to obtain a protective layer film.

[0039] In a preferred embodiment of the present invention, the raw materials of the low-temperature adaptation layer are mixed uniformly and produced to obtain the low-temperature adaptation layer film, which includes the following steps: Preheating the hydrogenated nitrile rubber at a temperature of 60-70° C. for 10-15 minutes; Pre-swell ethylene-vinyl acetate copolymer and diisononyl phthalate at 50-70°C for 30 minutes; The preheated hydrogenated nitrile rubber, pre-swollen ethylene-vinyl acetate copolymer, diisononyl phthalate, PVC, ethylene glycol ether, silane coupling agent, dicumyl peroxide, dinitrosopentamethylenetetramine and POE-g-MAH are added into a high-speed mixer, stirred at a speed of 800-1000 rpm for 15-20 minutes, and then a sheet is produced to obtain a low-temperature adaptation layer film.

[0040] In the present invention, during the preparation of the low-temperature adaptation layer film, ethylene-vinyl acetate copolymer (EVA) and diisononyl phthalate (DINP) are pre-swelled, mainly to improve the uneven dispersion problem caused by the polarity difference between the two. The infiltration of DINP weakens the interaction between the EVA molecular chains to achieve uniform swelling. This process not only softens the EVA and improves processing fluidity, but also promotes efficient mixing of EVA with other raw materials (such as HNBR, PVC), enhances the interfacial bonding strength of the multiphase system, and avoids low-temperature embrittlement. At the same time, pre-swelling helps to evenly disperse the foaming agent and the vulcanizing agent, optimizes the foaming and vulcanization reactions, and ensures that the material has both high elasticity and frost resistance. In addition, pre-swelling can also reduce processing energy consumption, shorten the blending time, and improve industrial production efficiency, ultimately allowing the low-temperature adaptation layer to form a stable multiphase structure to meet the application requirements of low-temperature scenarios such as cold chain.

[0041] According to a second aspect of the present invention, there is provided a use of the multi-layer copolymer foam material as described above in cold chain insulation.

[0042] Example 1 The preparation steps of a multi-layer copolymer foam material are as follows: Raw materials: 70 parts of high acrylonitrile butadiene rubber, 8 parts of aerogel powder, 3 parts of sodium bicarbonate, 5 parts of AC foaming agent, 1.5 parts of sulfur, 0.7 parts of accelerator N-cyclohexyl-2-benzothiazole sulfenamide (CZ), 1 part of co-crosslinking agent triallyl isocyanurate (TAIC), 30 parts of plasticizer dioctyl sebacate (DOS), 12 parts of PVC, and 5 parts of POE-g-MAH. Preheat the high acrylonitrile butadiene rubber at 60-70°C for 10-15 minutes; Add the preheated high acrylonitrile butadiene rubber, sodium bicarbonate, AC foaming agent, sulfur, accelerator CZ, co-crosslinking agent TAIC, plasticizer DOS, PVC and POE-g-MAH into a high-speed mixer and stir at a speed of 800-1000 rpm for 10-15 minutes; Finally, aerogel powder was added, and the mixture was stirred at a speed of 600 rpm for 5 to 10 minutes before being discharged to obtain a thermal insulation layer film.

[0043] The thermal insulation layer film is first allowed to stand at 120° C. for 5 minutes, then allowed to stand at 150° C. for 8 minutes, and then allowed to stand at 160° C. for 3 minutes for vulcanization and foaming, and finally cooled and formed to obtain the multilayer copolymer foam material.

[0044] Example 2 In this embodiment, the weight portion of POE-g-MAH is 3 parts, and the remaining steps and parameters are the same as those in Example 1.

[0045] Example 3 In this embodiment, the weight portion of POE-g-MAH is 7 parts, and the remaining steps and parameters are the same as those in Example 1.

[0046] Example 4 In this embodiment, the weight portion of POE-g-MAH is 10 parts, and the remaining steps and parameters are the same as those in Example 1.

[0047] Example 5 In this embodiment, the weight portion of aerogel powder is 5 parts, and the remaining steps and parameters are the same as those in Example 1.

[0048] Example 6 In this embodiment, the weight portion of aerogel powder is 10 parts, and the remaining steps and parameters are the same as those in Example 1.

[0049] Example 7 In this embodiment, the thermal insulation layer film is first allowed to stand at 110°C for 6 minutes, then at 145°C for 10 minutes, and then at 155°C for 4 minutes for vulcanization and foaming. Finally, it is cooled and formed to obtain the multilayer copolymer foam material. The remaining steps and parameters are the same as in Example 1.

[0050] Example 8 In this embodiment, the thermal insulation layer film is first allowed to stand at 130°C for 4 minutes, then at 155°C for 7 minutes, and then at 165°C for 2 minutes for vulcanization and foaming. Finally, it is cooled and formed to obtain the multi-layer copolymer foam material. The remaining steps and parameters are the same as those in Example 1.

[0051] Example 9 The preparation steps of a multi-layer copolymer foam material are as follows: Preparation of raw materials for the protective layer: 70 parts of EPDM rubber, 7 parts of calcium stearate, 5 parts of POE-g-MAH, 17 parts of precipitated silica, 12 parts of ultraviolet absorber UV-53, 10101 parts of antioxidant, 18 parts of plasticizer DOP, 25 parts of flame retardant aluminum hydroxide, 2 parts of AC foaming agent, 1.5 parts of sulfur and 0.7 parts of accelerator CZ.

[0052] Add all the raw materials into a high-speed blender, stir at a speed of 800-1000 rpm for 15-20 minutes, and then produce a sheet to obtain a protective layer film; Insulation layer raw materials: 70 parts of high acrylonitrile butadiene rubber, 8 parts of aerogel powder, 3 parts of sodium bicarbonate, 5 parts of AC foaming agent, 1.5 parts of sulfur, 0.7 parts of accelerator N-cyclohexyl-2-benzothiazole sulfenamide (CZ), 1 part of co-crosslinking agent triallyl isocyanurate (TAIC), 30 parts of plasticizer dioctyl sebacate (DOS), 12 parts of PVC, and 5 parts of POE-g-MAH; Preheat the high acrylonitrile butadiene rubber at 60-70°C for 10-15 minutes; Add the preheated high acrylonitrile butadiene rubber, sodium bicarbonate, AC foaming agent, sulfur, accelerator CZ, co-crosslinking agent TAIC, plasticizer DOS, PVC and POE-g-MAH into a high-speed mixer and stir at a speed of 800-1000 rpm for 10-15 minutes; Finally, add aerogel powder, stir at a speed of 600 rpm for 5 to 10 minutes, and then produce a sheet to obtain a thermal insulation layer film; Low temperature adaptation layer raw materials: 65 parts of hydrogenated nitrile rubber, 25 parts of PVC, 13 parts of ethylene vinyl acetate copolymer (EVA), 6 parts of ethylene glycol ether, 2 parts of silane coupling agent KH-560, 1.5 parts of dicumyl peroxide DCP, 22 parts of diisononyl phthalate (DINP), 2 parts of dinitrosopentamethylenetetramine, and 5 parts of POE-g-MAH; Preheating the hydrogenated nitrile rubber at a temperature of 60-70° C. for 15 minutes; Pre-swell ethylene-vinyl acetate copolymer and diisononyl phthalate at 50-70°C for 30 minutes; Preheated hydrogenated nitrile rubber, pre-swollen ethylene-vinyl acetate copolymer, diisononyl phthalate, PVC, glycol ether, silane coupling agent KH-560, dicumyl peroxide, dinitrosopentamethylenetetramine and POE-g-MAH were added to a high-speed blender, stirred at a speed of 800-1000 rpm for 15-20 minutes, and then discharged to obtain a low-temperature adaptation layer film; The protective layer film, the thermal insulation layer film and the low temperature adaptation layer film are blended and extruded to obtain a mixed film; The mixed film is placed in an oven and allowed to stand at 120° C. for 5 minutes, then at 150° C. for 8 minutes, and then at 160° C. for 3 minutes for vulcanization and foaming, and finally cooled and formed to obtain the multilayer copolymer foam material.

[0053] Comparative Example 1 In this comparative example, POE-g-MAH was not added, and the remaining steps and parameters were the same as those in Example 1.

[0054] Comparative Example 2 In this comparative example, no aerogel powder was added, and the remaining steps and parameters were the same as those in Example 1.

[0055] Comparative Example 3 In this comparative example, the thermal insulation layer film is placed in an oven for vulcanization and foaming. The oven temperature is 140° C. and the foaming time is 30 minutes. The remaining steps and parameters are the same as those in Example 1.

[0056] Performance Testing Burst resistance: Determined in accordance with BS EN 12332-1-1999: Rubber or plastics coated fabrics - Test for bursting strength. Part 1: Steel ball method; Tear strength test: measured in accordance with GB / T 529-2008 method; Thermal conductivity: Determined in accordance with GB / T10295-2008 "Determination of thermal conductivity and thermal resistance of insulating materials by steady-state heat flow method".

[0057] The test results are shown in Table 1: Table 1 Performance test results

[0058] The above data demonstrate that the POE-g-MAH dosage, aerogel powder addition, and vulcanization process are key factors influencing the performance of multilayer copolymer foam materials. POE-g-MAH enhances mechanical properties by improving the interfacial compatibility between NBR and PVC, achieving a burst force of 86.045N at a dosage of 5 phr. Aerogel powder optimizes the cell structure, with thermal conductivity as low as 0.027 W / (m·K) at 10 phr. In the three-stage vulcanization process, a combination of 120°C for 5 minutes, 150°C for 8 minutes, and 160°C for 3 minutes achieves a balanced crosslinking level and cell uniformity.

[0059] The three-layer design further enhances material performance. The protective layer's silica-EPDM network improves tear resistance, while the low-temperature adaptability layer buffers thermal stress, resulting in a bursting force of 88.0N and a thermal conductivity of 0.026W / (m·K) in Example 9. Comparative experiments show that the absence of POE-g-MAH, aerogel, or improper vulcanization process significantly degrades performance, validating the scientific nature of the formulation and process design.

Claims

1. A multi-layer copolymer foam material, characterized in that: The multilayer copolymer foam material comprises a thermal insulation layer, and the raw materials of the thermal insulation layer comprise high acrylonitrile butadiene rubber, aerogel powder, sodium bicarbonate, AC foaming agent, vulcanizing agent, accelerator, co-crosslinking agent, plasticizer, PVC and POE-g-MAH; The preparation method of the multi-layer copolymer foam material comprises the following steps: The raw materials of the thermal insulation layer are mixed evenly and sheeted to obtain a thermal insulation layer film; The thermal insulation layer film is first allowed to stand at 110-130° C. for 4-6 minutes, then allowed to stand at 145-155° C. for 7-10 minutes, and then allowed to stand at 155-165° C. for 2-4 minutes for vulcanization and foaming, and finally cooled and formed to obtain the multi-layer copolymer foam material.

2. The multilayer copolymer foam material according to claim 1, wherein The step of uniformly mixing the raw materials of the thermal insulation layer and producing the film to obtain the thermal insulation layer film comprises the following steps: Preheating the high acrylonitrile butadiene rubber at a temperature of 60-70° C. for 10-15 minutes; Add the preheated high acrylonitrile butadiene rubber, sodium bicarbonate, AC foaming agent, vulcanizing agent, accelerator, co-crosslinking agent, plasticizer, PVC and POE-g-MAH into a high-speed mixer and stir at a speed of 800-1000 rpm for 10-15 minutes; Finally, aerogel powder is added, and the mixture is stirred at a speed of 600 rpm for 5 to 10 minutes before being discharged to obtain a thermal insulation layer film.

3. The multilayer copolymer foam material according to claim 1, wherein The multilayer copolymer foam material further comprises a protective layer, the raw materials of which include EPDM rubber, calcium stearate, POE-g-MAH, precipitated silica, ultraviolet absorber, antioxidant, plasticizer, flame retardant, AC foaming agent, vulcanizer and accelerator.

4. The multilayer copolymer foam material according to claim 3, wherein The ultraviolet absorber includes UV-531, the antioxidant includes antioxidant 1010, the plasticizer includes dioctyl phthalate, and the flame retardant includes aluminum hydroxide.

5. The multi-layer copolymer foam material according to claim 3, wherein: The multi-layer copolymer foam material also includes a low-temperature adaptation layer, and the raw materials of the low-temperature adaptation layer also include hydrogenated nitrile rubber, PVC, ethylene-vinyl acetate copolymer, ethylene glycol ether, silane coupling agent, diisopropylbenzene peroxide, diisononyl phthalate, dinitrosopentamethylenetetramine and POE-g-MAH; the mass ratio of the hydrogenated nitrile rubber to PVC is 6~7:2~3.

6. The multilayer copolymer foam material according to claim 5, wherein The heat-insulating layer is located between the protective layer and the low-temperature adaptability layer; the protective layer, the heat-insulating layer and the low-temperature adaptability layer are an integral structure, and are integrally formed by co-extrusion and vulcanization foaming.

7. A method for preparing a multi-layer copolymer foam material according to claim 6, characterized in that: The following steps are involved: The raw materials of the protective layer are mixed evenly and sheeted to obtain a protective layer film; The raw materials of the thermal insulation layer are mixed evenly and sheeted to obtain a thermal insulation layer film; The raw materials of the low temperature adaptation layer are mixed evenly and sheeted to obtain a low temperature adaptation layer film; The protective layer film, the thermal insulation layer film and the low temperature adaptation layer film are blended and extruded to obtain a mixed film; The mixed film is first allowed to stand at 110-130° C. for 4-6 minutes, then allowed to stand at 145-155° C. for 7-10 minutes, then allowed to stand at 155-165° C. for 2-4 minutes for vulcanization and foaming, and finally cooled and formed to obtain the multilayer copolymer foam material.

8. The preparation method according to claim 7, wherein The steps of uniformly mixing the raw materials for the protective layer and producing the protective layer film include: The raw materials of the protective layer are stirred at a rotation speed of 800-1000 rpm for 15-20 minutes and then produced into a sheet to obtain a protective layer film.

9. The preparation method according to claim 7, wherein The step of uniformly mixing the raw materials of the low-temperature adaptation layer and producing the film to obtain the low-temperature adaptation layer film comprises the following steps: Preheating the hydrogenated nitrile rubber at a temperature of 60-70° C. for 10-15 minutes; Pre-swell ethylene-vinyl acetate copolymer and diisononyl phthalate at 50-70°C for 30 minutes; The preheated hydrogenated nitrile rubber, pre-swollen ethylene-vinyl acetate copolymer, diisononyl phthalate, PVC, ethylene glycol ether, silane coupling agent, dicumyl peroxide, dinitrosopentamethylenetetramine and POE-g-MAH are added into a high-speed mixer, stirred at a speed of 800-1000 rpm for 15-20 minutes, and then a sheet is produced to obtain a low-temperature adaptation layer film.

10. Use of the multilayer copolymer foam material according to any one of claims 1 to 6 in cold chain insulation.

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