CN113547810B

CN113547810B - Multilayer polymer foam material and preparation method thereof

Info

Publication number: CN113547810B
Application number: CN202010328219.XA
Authority: CN
Inventors: 庞永艳; 郭冰洁; 郑文革; 曹诣宇
Original assignee: Ningbo Institute of Material Technology and Engineering of CAS
Current assignee: Ningbo Institute of Material Technology and Engineering of CAS
Priority date: 2020-04-23
Filing date: 2020-04-23
Publication date: 2023-09-26
Anticipated expiration: 2040-04-23
Also published as: CN113547810A

Abstract

The application relates to a multilayer polymer foaming material and a preparation method thereof, wherein the preparation method comprises the following steps: providing a first polymer and nanoparticles, and mixing the first polymer and the nanoparticles to obtain a mixture; providing a second polymer, preparing the second polymer and the mixture into a laminated structure by a multi-layer coextrusion method, wherein the laminated structure comprises at least one second polymer layer and at least one mixed layer, and the second polymer and the first polymer are polymers with the same monomer; and foaming the laminated structure to foam the mixed layers in the laminated structure to form a foaming layer, so as to obtain the multi-layer polymer foaming material comprising at least one film layer and at least one foaming layer. The preparation method is simple, and the obtained multilayer polymer foaming material has no defect inside and has excellent optical, electromagnetic shielding, sound absorption, heat insulation, mechanical properties and the like.

Description

Multilayer polymer foam material and preparation method thereof

Technical Field

The application relates to the technical field of high polymer materials, in particular to a multilayer polymer foaming material and a preparation method thereof.

Background

The polymer foam material is a microporous material having numerous bubbles in the inside, which is based on a polymer such as plastic, rubber, elastomer or natural polymer material, and can be regarded as a composite material using gas as a filler. Scientific researches find that the solid material layer is fused in the polymer foaming material, so that the advantages of the foaming layer and the solid layer can be fused, the defect of a single structure is overcome, and the material is endowed with better performance.

Currently, such foamed layer and solid layer composite multilayer polymeric foamed materials are mainly prepared by multilayer coextrusion. Such as: according to the method (1), a chemical foaming agent is added into a target foaming layer, the foaming agent is decomposed to form bubbles in the coextrusion process, and the multi-layer polymer foaming material compounded by the foaming layer and the solid layer is obtained.

And (2) forming an alternate layered material by co-extrusion or layer-by-layer assembly and hot pressing of the two polymers, and then foaming by using a kettle-pressure foaming device to obtain the multi-layer polymer foaming material with the composite foaming layer and the solid layer. The method uses two different polymers, and most of the polymers are incompatible, so that the layers are easily separated from each other or interlayer bubble defects occur in the foaming process, which is bad for the performance of the multi-layer polymer foaming material. In addition, the growth of cells in the foam layer is also limited by the solid layer, resulting in the foam layer failing to achieve a higher expansion ratio.

Disclosure of Invention

Based on this, it is necessary to provide a multi-layer polymer foam material and a method for producing the same in view of the above-mentioned problems; the multilayer polymer foaming material comprises a film layer and a foaming layer, has no defects in the interior and has excellent optical, electromagnetic shielding, sound absorption, heat insulation, mechanical properties and the like.

A method of preparing a multi-layer polymeric foam comprising:

providing a first polymer and nanoparticles, and mixing the first polymer and the nanoparticles to obtain a mixture;

providing a second polymer, and preparing the second polymer and the mixture into a laminated structure by a multi-layer coextrusion method, wherein the laminated structure comprises at least one second polymer layer and at least one mixed layer, and the second polymer and the first polymer are the same polymer of monomers;

and foaming the laminated structure to enable the mixed layer in the laminated structure to be foamed to form a foaming layer, so as to obtain the multi-layer polymer foaming material comprising at least one film layer and at least one foaming layer.

In one embodiment, the second polymer layer has a thickness less than the thickness of the hybrid layer.

In one embodiment, the second polymer layer has a thickness of 100 μm or less and the mixed layer has a thickness of 10 μm or more.

In one embodiment, the second polymer layer has a thickness of 1 μm to 100 μm and the hybrid layer has a thickness of less than 3mm.

In one embodiment, the second polymer layer and the mixed layer are alternately laminated in the laminated structure.

In one embodiment, the laminate structure has a thickness of 3mm or less.

In one embodiment, the difference in melt index between the first polymer and the second polymer is 5 or less.

In one embodiment, the mass percent of the nanoparticles in the mixture is 0.001wt% to 10wt%.

The multi-layer polymer foam material is prepared by the preparation method and comprises at least one film layer and at least one foam layer, wherein the film layer is made of a second polymer, the foam layer comprises a first polymer and nano particles, and the second polymer and the first polymer are the same polymer as a monomer.

In one embodiment, the thickness of the film layer is 100 μm or less, the expansion ratio of the multi-layer polymer foam material is 5-50 times, and the pore size of the cells is 0.01 μm to 100 μm.

In the preparation method, the first polymer and the second polymer are polymers with the same monomer and have the same or similar melt indexes, so that in the coextrusion process, a certain flow mixing effect exists between the adjacent second polymer layers and the mixed layer, so that the second polymer layers are thinned, the mixed layer is thickened, nano particles are further contained in the mixed layer, heterogeneous nucleation sites can be provided in the foaming process, and the nucleation barrier of the mixed layer is lower than that of the second polymer layers. Therefore, in the foaming process, cells in the mixed layer are extremely easy to form and grow, the foaming becomes a foaming layer, and the second polymer layer is too thin to satisfy the conditions of cell nucleation and growth, and cannot be foamed, so that the second polymer layer becomes a solid film layer. Thus, the multilayer polymer foam material comprising the film layer and the foam layer is prepared by the special cell nucleation growth mode, and the method is simple and does not need to use chemical foaming agents.

In addition, the multi-layer polymer foaming material prepared by the application uses the polymers with the same monomers, so that two adjacent layers can flow and be mixed in the coextrusion process, the interface is compatible, the interlayer binding force is large, and layering or interlayer defects are not caused in the foaming process, so that the multi-layer polymer foaming material has good mechanical properties. Meanwhile, the solid film layer is thinner, and the interlayer binding force is larger, so that the gas escape of the mixed layer is less when the mixed layer is foamed, the multilayer polymer foaming material can be ensured to have larger expansion multiplying power, and the multilayer polymer foaming material has excellent optical, electromagnetic shielding, sound absorption, heat insulation, mechanical properties and the like.

Drawings

FIG. 1 is an electron micrograph of a multilayer polymer foam obtained in example 1 of the present application;

FIG. 2 is an electron micrograph of a single-layered polystyrene foam obtained in comparative example 1 of the present application;

FIG. 3 is an electron micrograph of a single-layered polystyrene/nano-silica composite foam material obtained in comparative example 2 of the present application.

Detailed Description

The multi-layer polymer foam material and the preparation method thereof provided by the application are further described below.

The preparation method of the multilayer polymer foaming material provided by the application comprises the following steps:

s1, providing a first polymer and nanoparticles, and mixing the first polymer and the nanoparticles to obtain a mixture;

s2, providing a second polymer, and preparing the second polymer and the mixture into a laminated structure by a multi-layer coextrusion method, wherein the laminated structure comprises at least one second polymer layer and at least one mixed layer, and the second polymer and the first polymer are the same polymer as each other in a monomer manner;

and S3, foaming the laminated structure, and foaming the mixed layer in the laminated structure to form a foaming layer to obtain the multi-layer polymer foaming material comprising at least one film layer and at least one foaming layer.

In step S1, the first polymer includes one of polypropylene, polyethylene, polystyrene, polymethyl methacrylate, polylactic acid, polyolefin elastomer, and polycarbonate.

The nano particles comprise at least one of silicon dioxide, calcium carbonate, organoclay, polytetrafluoroethylene, talcum powder, carbon black, carbon nano tubes, graphene, mxene and magnetic nano particles, and can be used as heterogeneous nucleating agents of bubbles, so that the nucleation of the bubbles is facilitated, the cell density is increased, and the functionality is given to the material.

The first polymer and the nanoparticles may be mixed by a solution blending method, a mechanical blending method, or the like to obtain a mixture. In the mixture, when the nano particles are increased in a smaller range, the size and the density of the foam holes of the mixed layer are reduced during foaming, so that the expansion multiplying power of the obtained foaming layer is improved; however, when the nanoparticle content exceeds the optimum content, the hardness of the mixed layer is too high, which is disadvantageous for cell growth. Thus, the mass percentage of the nanoparticles in the mixture is 0.001wt% to 10wt%, preferably 0.1wt% to 0.5wt%.

In step S2, the second polymer and the first polymer are polymers with the same monomer and the same or similar melt indexes, so that in the coextrusion process, a certain flow mixing effect exists between the adjacent second polymer layers and the mixed layer, so that the second polymer layers are thinned, and the mixed layer is thickened. Furthermore, the hybrid layer also contains nanoparticles that can provide heterogeneous nucleation sites during foaming such that the hybrid layer has a lower nucleation barrier than the second polymer layer. Therefore, in the foaming process of step S3, cells in the mixed layer are extremely easy to form and grow, foaming becomes a foamed layer, and the second polymer layer is too thin to satisfy the conditions of cell nucleation and growth, and cannot be foamed to become a solid film layer, thereby obtaining a multilayer polymer foamed material including the film layer and the foamed layer.

In order to make it easier for the mixed layer to foam into a foamed layer during foaming, while the second polymer layer cannot foam into a solid film layer, the thickness of the second polymer layer in the lamellar structure is smaller than the thickness of the mixed layer.

Further, it is considered that the same polymer as the monomer has a different melt index due to a different molecular weight, and has a difference in fluidity. In order to ensure a better mixed flow between the adjacent second polymer layer and the mixed layer during coextrusion, the difference in melt indices of the first polymer and the second polymer is less than or equal to 5, preferably less than or equal to 3, more preferably the melt indices are the same.

The smaller the difference between the melt indexes of the first polymer and the second polymer, the closer the flowability of the polymers of the adjacent layers is, so that the larger the difference between the thicknesses of the second polymer layer and the mixed layer in the co-extrusion laminated structure is, which is more beneficial to the preparation of the multi-layer polymer foam material of the application.

In addition, as the second polymer layer and the mixed layer have certain mixing effect due to the flowing of the polymers during multi-layer coextrusion, the interlayer binding force of each unit layer in the lamellar structure is large, and layering or interlayer defects cannot occur in the foaming process of the step S3, so that the obtained multi-layer polymer foaming material has better mechanical properties.

Further, in order to ensure that the thickness of the second polymer layer cannot satisfy the conditions of cell nucleation and growth, so that the second polymer layer cannot foam into a solid film layer, the thickness of the second polymer layer is preferably 100 μm or less.

In addition, the thinner second polymer layer does not limit the growth of cells in the mixed layer during foaming, but can also reduce gas escape at the time of foaming of the mixed layer, so the thickness of the second polymer layer may be further preferably 50 μm or less, more preferably 25 μm or less, to better secure the expansion ratio of the mixed layer.

Of course, in view of the mechanical properties of the multilayer polymer foam, the thickness of the second polymer layer is preferably 1 μm to 100. Mu.m, more preferably 1 μm to 50. Mu.m, still more preferably 1 μm to 25. Mu.m.

Further, although the mixed layer has a low nucleation barrier and is extremely easily foamed, in order to ensure that the thickness of the mixed layer is greater than the critical nucleation size of bubbles, it is ensured that the gas can nucleate and grow, and in the lamellar structure, the thickness of the mixed layer is 10 μm or more.

Of course, the thickness of the mixed layer is less than 3mm in consideration of the mechanical properties of the multi-layer polymer foam material and the limit of the autoclave foaming.

The number of mixed layers in the sheet structure may be one or more, and the number of second polymer layers may be one or more, so that the sheet structure is at least a two-layer structure in which the mixed layers and the second polymer layers are stacked.

In view of the fact that the film layers and the foam layers are alternately laminated and distributed in number, the multi-layer polymer foam material can have strength and toughness, so that the mechanical properties of the multi-layer polymer foam material can be enhanced along with the increase of the number of layers, and meanwhile, the optical, electromagnetic shielding, sound absorption, heat insulation and other properties of the multi-layer polymer foam material are more excellent, therefore, in the laminated structure, the number of the second polymer layers and the number of the mixed layers are preferably multiple, and the second polymer layers and the mixed layers are alternately laminated and distributed.

When the sum of the layers of the second polymer layer and the mixed layer in the sheet structure is even, the foamed multi-layer polymer foam material is a structure in which the foamed layers and the film layers are alternately laminated and distributed.

When the sum of the layers of the second polymer layer and the mixed layer in the sheet structure is an odd number, and the number of the second polymer layers is larger than that of the mixed layer, the outermost layers of the foamed multi-layer polymer foam material obtained by foaming are all film layers, and the inside is a structure in which the foaming layers or the foaming layers and the film layers are alternately laminated and distributed.

When the sum of the layers of the second polymer layer and the mixed layer in the sheet structure is an odd number and the number of the second polymer layers is smaller than the number of the mixed layers, the outermost layers of the foamed multi-layer polymer foam material are all foam layers, and the inner layers are thin film layers or the structure that the foam layers and the thin film layers are alternately laminated and distributed.

Therefore, the multi-layer polymer foaming material can be suitable for different application scenes.

In view of the fact that foaming cannot be performed when the laminate structure is too thick, the thickness of the laminate structure is preferably 3mm or less.

In step S3, the foaming process includes: and placing the laminated structure in an autoclave, introducing foaming gas, and after the laminated structure reaches the saturation pressure, foaming by adopting an intermittent foaming method to obtain the multi-layer polymer foaming material comprising at least one film layer and at least one foaming layer.

Wherein the foaming gas comprises one of carbon dioxide and nitrogen.

The intermittent foaming method is classified into a rapid temperature rising foaming method and a rapid pressure releasing foaming method. When the rapid heating foaming method is adopted, the saturation pressure is 2MPa-10MPa, the saturation time is 24h-168h, the temperature of the autoclave is 10 ℃ to 100 ℃, after saturation is completed, the lamellar structure reaching the saturation pressure is taken out and placed in a medium with the temperature of 100 ℃ to 200 ℃ for foaming, the foaming time is 5s-60s, and the medium comprises at least one of simethicone and glycerol.

When the rapid pressure relief foaming is adopted, the saturation pressure is 10MPa-30MPa, the saturation time is 5h-72h, the temperature of the high-pressure kettle is 10-100 ℃, after the saturation is finished, or the temperature in the high-pressure kettle is adjusted to 40-160 ℃, or the temperature in the high-pressure kettle is kept unchanged, the high-pressure kettle is relieved, the pressure relief speed is greater than 1MPa/s, and the foaming is finished.

Therefore, the multilayer polymer foaming material comprising the film layer and the foaming layer is prepared by the special cell nucleation growth mode, and the preparation method is simple, safe, efficient and good in controllability, and does not need to use a chemical foaming agent.

In addition, the application can regulate and control the size, shape, expansion ratio and the like of the bubble hole in the foaming layer by regulating and controlling the saturated pressure, saturated time, saturated temperature, foaming time and other foaming conditions, and can regulate and control the performance of the multi-layer polymer foaming material.

The application also provides a multilayer polymer foaming material obtained by the preparation method, which comprises at least one film layer and at least one foaming layer, wherein the film layer is made of a second polymer, the foaming layer is made of a first polymer and nano particles, and the second polymer and the first polymer are the same polymer as a monomer.

Further, the thickness of the film layer is less than or equal to 100 mu m, the foaming multiplying power of the multi-layer polymer foaming material is 5 times to 50 times, and the pore size of the foam cells is 0.01 mu m to 100 mu m.

Preferably, the thickness of the film layer is 1 μm to 100. Mu.m, more preferably 1 μm to 50. Mu.m, still more preferably 1 μm to 25. Mu.m.

Preferably, the expansion ratio of the multi-layer polymer foam material is 10 times to 50 times, and the pore size of the cells is 0.01 mu m to 80 mu m.

Further, when the sum of the layers of the film layer and the foaming layer is even and greater than 2, the multi-layer polymer foaming material has a structure in which the foaming layers and the film layer are alternately laminated and distributed.

When the sum of the layers of the film layer and the foaming layer is odd, and the number of the film layers is larger than that of the foaming layers, the outermost layers of the multi-layer polymer foaming materials are the film layers, and the inner layers are the foaming layers or the foaming layers and the film layers are alternately laminated and distributed.

When the sum of the layers of the film layer and the foaming layer is odd, and the number of the film layers is smaller than that of the foaming layers, the outermost layers of the multi-layer polymer foaming materials are all foaming layers, and the inner layers are the film layers or the structure that the foaming layers and the film layers are alternately laminated and distributed.

Therefore, the multilayer polymer foaming material has no defects in the interior, has excellent mechanical properties, and most importantly, has excellent optical, electromagnetic shielding, sound absorption, heat insulation, mechanical properties and the like due to the special structure, and can be suitable for different application scenes.

Hereinafter, the multi-layered polymer foam and the method of preparing the same will be further described by the following specific examples.

Example 1

The nano silicon dioxide and the first polystyrene are blended to obtain a mixture, wherein the mass percentage of the nano silicon dioxide is 0.1wt%.

The second polystyrene and the mixture were made into a sheet having a width of 5cm, a thickness of about 1mm and a number of layers of 128 layers by a multi-layer coextrusion apparatus, wherein the polystyrene layer in the sheet had a thickness of 5.5 μm and the mixed layer had a thickness of 10.1 μm, and the polystyrene layer and the mixed layer were alternately laminated and distributed, and the difference in melt index between the second polystyrene and the first polystyrene was 4.5.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is carbon dioxide, the saturation pressure is 2MPa, the saturation time is 72h, the temperature of the autoclave is 25 ℃, after saturation is completed, taking out the sheet reaching the saturation pressure, placing the sheet into dimethyl silicone oil with the temperature of 130 ℃ for foaming for 15s, and obtaining the multi-layer polymer foam material with alternately laminated film layers and foaming layers as shown in figure 1, wherein the thickness of the film layers is 5.5 mu m.

Example 2

And blending the nano calcium carbonate with the first polypropylene to obtain a mixture, wherein the mass percentage of the nano calcium carbonate is 1wt%.

The second polypropylene and the mixture were made into a sheet having a width of 10cm, a thickness of 2mm and a number of layers of 32 by a multilayer coextrusion apparatus, wherein the polypropylene layer in the sheet had a thickness of 10 μm and the mixed layer had a thickness of 115 μm, and the polypropylene layer and the mixed layer were alternately laminated and distributed, and the difference in melt index between the first polypropylene and the second polypropylene was 0.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is carbon dioxide, the saturation pressure is 5MPa, the saturation time is 24h, the temperature of the autoclave is 25 ℃, after saturation is completed, taking out the sheet reaching the saturation pressure, placing the sheet into glycerin with the temperature of 120 ℃ for foaming, and the foaming time is 20s, so as to obtain the multilayer polymer foaming material with alternately laminated film layers and foaming layers, wherein the thickness of the film layers is 10 mu m.

Example 3

And blending the carbon nano tube with the first polyethylene to obtain a mixture, wherein the mass percent of the carbon nano tube is 10wt%.

The second polyethylene and the mixture were made into a sheet having a width of 2cm, a thickness of 1mm and a number of layers of 32 layers by a multilayer coextrusion apparatus, the thickness of the polyethylene layer in the sheet was 12.5 μm, the thickness of the mixed layer was 50 μm, and the polyethylene layer and the mixed layer were alternately laminated, and the difference in melt index between the first polyethylene and the second polyethylene was 2.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is carbon dioxide, the saturation pressure is 6MPa, the saturation time is 128h, the temperature of the autoclave is 25 ℃, after saturation is completed, taking out the sheet reaching the saturation pressure, placing the sheet into glycerin with the temperature of 150 ℃ for foaming for 20s, and obtaining the multilayer polymer foaming material with alternately laminated film layers and foaming layers, wherein the thickness of the film layers is 12.5 mu m.

Example 4

And blending graphene and first polymethyl methacrylate to obtain a mixture, wherein the mass percentage of the graphene is 5wt%.

The second polymethyl methacrylate and the mixture were made into a sheet having a width of 5cm, a thickness of 3mm and a number of layers of 64 layers by a multilayer coextrusion apparatus, wherein the polymethyl methacrylate layer in the sheet had a thickness of 23.75 μm and the mixed layer had a thickness of 70 μm, and the polymethyl methacrylate layer and the mixed layer were alternately laminated and distributed, and the difference in melt index between the first polymethyl methacrylate and the second polymethyl methacrylate was 2.5.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is carbon dioxide, the saturation pressure is 3MPa, the saturation time is 48h, the temperature of the autoclave is 25 ℃, after saturation is completed, taking out the sheet reaching the saturation pressure, placing the sheet into glycerin with the temperature of 120 ℃ for foaming, and the foaming time is 50s, so as to obtain the multilayer polymer foaming material with alternately laminated film layers and foaming layers, wherein the thickness of the film layers is 23.75 mu m.

Example 5

And blending the nano silicon dioxide and the first polylactic acid to obtain a mixture, wherein the mass percentage of the nano silicon dioxide is 1wt%.

The second polylactic acid and the mixture were made into a sheet having a width of 1cm, a thickness of about 2mm and a number of layers of 256 layers by a multilayer coextrusion apparatus, wherein the thickness of the polylactic acid layer in the sheet was 4 μm, the thickness of the mixed layer was 11.6 μm, and the polylactic acid layer and the mixed layer were alternately laminated and distributed, and the difference between the first polylactic acid and the second polylactic acid was 2.7.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is carbon dioxide, the saturation pressure is 8MPa, the saturation time is 48h, the temperature of the autoclave is 25 ℃, after saturation is completed, taking out the sheet reaching the saturation pressure, placing the sheet into glycerin with the temperature of 120 ℃ for foaming, and the foaming time is 20s, so as to obtain the multilayer polymer foaming material with alternately laminated film layers and foaming layers, wherein the thickness of the film layers is 4 mu m.

Example 6

And blending the nano calcium carbonate with the first polycarbonate to obtain a mixture, wherein the mass percentage of the nano calcium carbonate is 1wt%.

The second polycarbonate and the mixture were formed into a sheet having a width of 3cm, a thickness of about 2mm and a number of layers of 256 layers by a multi-layer coextrusion apparatus, wherein the polycarbonate layer in the sheet had a thickness of 4.4 μm and the mixed layer had a thickness of 11.2 μm, and the polycarbonate layer and the mixed layer were alternately laminated, and the difference between the first polycarbonate and the second polycarbonate was 3.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is carbon dioxide, the saturation pressure is 4MPa, the saturation time is 72h, the temperature of the autoclave is 25 ℃, after saturation is completed, taking out the sheet reaching the saturation pressure, placing the sheet into glycerin with the temperature of 110 ℃ for foaming for 30s, and obtaining the multilayer polymer foaming material with alternately laminated film layers and foaming layers, wherein the thickness of the film layers is 4.4 mu m.

Example 7

The second polystyrene and the mixture were made into a sheet having a width of 8cm, a thickness of 2mm and a number of layers of 32 by a multilayer coextrusion apparatus, the polystyrene layer in the sheet had a thickness of 25 μm and the mixed layer had a thickness of 100 μm, and the polystyrene layer and the mixed layer were alternately laminated and distributed, and the difference in melt index between the second polystyrene and the first polystyrene was 2.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is nitrogen, the saturation pressure is 20MPa, the saturation time is 72h, the temperature of the autoclave is 100 ℃, after saturation is finished, the temperature of the autoclave is adjusted to 70 ℃, the pressure of the autoclave is relieved, the pressure relief speed is 3MPa/s, and foaming is finished, so that the multilayer polymer foam material with alternately laminated film layers and foaming layers is obtained, wherein the thickness of the film layers is 25 mu m.

Example 8

The second polystyrene and the mixture were made into a sheet having a width of 8cm, a thickness of 2mm and a number of layers of 32 by a multilayer coextrusion apparatus, the polystyrene layer in the sheet had a thickness of 15 μm and the mixed layer had a thickness of 110 μm, and the polystyrene layer and the mixed layer were alternately laminated and distributed, and the difference in melt index between the second polystyrene and the first polystyrene was 1.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is nitrogen, the saturation pressure is 15MPa, the saturation time is 72h, the temperature of the autoclave is 100 ℃, after saturation is finished, the temperature of the autoclave is adjusted to 70 ℃, the pressure of the autoclave is relieved, the pressure relief speed is 5MPa/s, and foaming is finished, so that the multilayer polymer foam material with alternately laminated film layers and foaming layers is obtained, wherein the thickness of the film layers is 15 mu m.

Example 9

The second polyethylene and the mixture were made into a sheet having a width of 10cm, a thickness of 1mm and a number of layers of 16 layers by a multilayer coextrusion apparatus, the thickness of the polyethylene layer in the sheet was 20 μm, the thickness of the mixed layer was 105 μm, and the polyethylene layer and the mixed layer were alternately laminated, and the difference in melt index between the second polyethylene and the first polyethylene was 1.5.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is nitrogen, the saturation pressure is 30MPa, the saturation time is 8h, the temperature of the autoclave is 25 ℃, after saturation is finished, the temperature of the autoclave is 100 ℃, the pressure relief is carried out on the autoclave, the pressure relief speed is 2MPa/s, and foaming is finished, so that the multilayer polymer foaming material with alternately laminated film layers and foaming layers is obtained, wherein the thickness of the film layers is 20 mu m.

Example 10

And blending graphene and first polymethyl methacrylate to obtain a mixture, wherein the mass percentage of the graphene is 10wt%.

The second polymethyl methacrylate and the mixture were produced into a sheet having a width of 3cm, a thickness of 3mm and a number of layers of 64 layers by a multilayer coextrusion apparatus, wherein the polymethyl methacrylate layer in the sheet had a thickness of 23.75 μm and the mixed layer had a thickness of 70 μm, and the polymethyl methacrylate layer and the mixed layer were alternately laminated and distributed, and the difference in melt index between the second polymethyl methacrylate and the first polymethyl methacrylate was 2.6.

And (3) placing the multilayer polymer sheet into an autoclave for saturation, wherein saturated gas is nitrogen, the saturation pressure is 30MPa, the saturation time is 8h, the temperature of the autoclave is 25 ℃, after saturation is finished, the temperature of the autoclave is 100 ℃, the pressure of the autoclave is relieved, the pressure relief speed is 7MPa/s, foaming is finished, and the multilayer polymer foam material with alternately laminated film layers and foaming layers is obtained, wherein the thickness of the film layers is 23.75 mu m.

Example 11

The second polylactic acid and the mixture were made into a sheet having a width of 8cm, a thickness of 3mm and a number of layers of 64 layers by a multilayer coextrusion apparatus, wherein the thickness of the polylactic acid layer in the sheet was 14.75 μm, the thickness of the mixed layer was 79 μm, and the polylactic acid layer and the mixed layer were alternately laminated and distributed, and the difference in melt index of the first polylactic acid and the second polylactic acid was 1.5.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is nitrogen, the saturation pressure is 10MPa, the saturation time is 28h, the temperature of the autoclave is 60 ℃, after saturation is finished, the temperature of the autoclave is adjusted to 130 ℃, the pressure relief is carried out on the autoclave, the pressure relief speed is 3MPa/s, and foaming is finished, so that the multilayer polymer foaming material with alternately laminated film layers and foaming layers is obtained, wherein the thickness of the film layers is 14.75 mu m.

Example 12

The second polycarbonate and the mixture were made into a sheet having a width of 9cm, a thickness of 2mm and a number of layers of 128 layers by a multilayer coextrusion apparatus, wherein the polycarbonate layer in the sheet had a thickness of 6.25 μm and the mixed layer had a thickness of 25 μm, and the polycarbonate layer and the mixed layer were alternately laminated and distributed, and the difference in melt index between the first polycarbonate and the second polycarbonate was 2.

And (3) placing the sheet into an autoclave for saturation, wherein saturated gas is nitrogen, the saturation pressure is 10MPa, the saturation time is 28h, the temperature of the autoclave is 60 ℃, after saturation is finished, the temperature of the autoclave is adjusted to 130 ℃, the pressure of the autoclave is relieved, the pressure relief speed is 6MPa/s, foaming is finished, and the multilayer polymer foam material with alternately laminated film layers and foaming layers is obtained, wherein the thickness of the film layers is 6.25 mu m.

Comparative example 1

And (3) pressing the polystyrene into a sheet with the thickness of 1mm, putting the sheet into an autoclave for saturation, wherein the saturated gas is carbon dioxide, the saturation pressure is 2MPa, the saturation time is 72h, the temperature of the autoclave is 25 ℃, taking out the sheet with the saturation pressure after the saturation is finished, and putting the sheet into dimethyl silicone oil with the temperature of 130 ℃ for foaming for 15s to obtain the single-layer polystyrene foaming material shown in figure 2.

Comparative example 2

The nano silicon dioxide and polystyrene are blended to obtain a mixture, wherein the mass percentage of the nano silicon dioxide is 1wt%.

Pressing the mixture into a sheet with the thickness of 1mm, putting the sheet into an autoclave for saturation, wherein the saturated gas is carbon dioxide, the saturation pressure is 2MPa, the saturation time is 72h, the temperature of the autoclave is 25 ℃, after the saturation is completed, taking out the sheet with the saturation pressure, putting the sheet into dimethyl silicone oil with the temperature of 130 ℃ for foaming, and the foaming time is 15s, thus obtaining the single-layer polystyrene/nano silicon dioxide composite foaming material shown in figure 3.

The foam materials of examples 1-12 and comparative examples 1-2 were characterized for cell structure using a ZEISS scanning electron microscope, and the results were: examples 1 to 12 were multilayer materials in which film layers and foam layers were alternately laminated, and comparative examples 1 to 2 were single-layer materials.

The foaming materials in examples 1-12 and comparative examples 1-2 were subjected to mechanical property characterization according to standard GB/T8813, and simultaneously subjected to heat insulation property characterization according to standard ASTME 1461 by using a laser heat conduction instrument, and specific results are shown in Table 1.

TABLE 1

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims

1. A method for preparing a multilayer polymeric foam material, comprising:

providing a first polymer and nanoparticles, and mixing the first polymer and the nanoparticles to obtain a mixture, wherein the mass percent of the nanoparticles in the mixture is 0.001-10wt%;

providing a second polymer, and preparing the second polymer and the mixture into an alternate laminated structure by a multi-layer coextrusion method, wherein the laminated structure comprises at least one second polymer layer and at least one mixed layer, the second polymer and the first polymer are the same polymer of monomers, the difference of melt indexes is less than or equal to 5, the thickness of the second polymer layer is less than that of the mixed layer, the thickness of the second polymer layer is 1-100 mu m, the thickness of the mixed layer is less than 3mm, and the thickness of the mixed layer is more than or equal to 10 mu m;

foaming the laminated structure to form a foaming layer by foaming the mixed layer in the laminated structure to obtain a multi-layer polymer foaming material comprising at least one film layer and at least one foaming layer, wherein the foaming process comprises the following steps: placing the laminated structure in an autoclave, introducing foaming gas, and after the laminated structure reaches saturation pressure, foaming by adopting an intermittent foaming method, wherein the foaming multiplying power of the multi-layer polymer foaming material is 5-50 times, and the pore size of the foam holes is 0.01-100 mu m.

2. The method of producing a multilayer polymeric foam according to claim 1, wherein the thickness of the second polymeric layer is 1 μm to 50 μm.

3. The method for producing a multilayer polymer foam according to claim 1, wherein the thickness of the laminate structure is 3mm or less.

4. The method for producing a multilayer polymer foam according to claim 1, wherein the difference in melt index between the first polymer and the second polymer is 3 or less.

5. The method for preparing a multi-layer polymer foam according to claim 1, wherein the mass percentage of the nanoparticles in the mixture is 0.1wt% to 0.5wt%.

6. A multilayer polymer foam material characterized by being obtained by the production method according to any one of claims 1 to 5.

7. The multilayer polymer foam material according to claim 6, wherein the thickness of the film layer is 100 μm or less, the expansion ratio of the multilayer polymer foam material is 10-50 times, and the pore size of the cells is 0.01 μm to 80 μm.