Low-smoke fireproof heat-resistant aluminum foil reinforced polyolefin foam as well as preparation method and application thereof

Abstract

The invention belongs to the field of high polymer materials, and particularly relates to low-smoke fireproof heat-resistant aluminum foil reinforced polyolefin foam as well as a preparation method and application thereof. The aluminum foil reinforced polyolefin foam comprises polyolefin foam and an aluminum foil structure arranged on the surface of the polyolefin foam, the polyolefin foam is formed by foaming polyolefin resin, a flame retardant, a foaming agent, an adhesive and an auxiliary agent, the aluminum foil structure comprises an aluminum foil layer; the flame retardant comprises a phosphorus element, a nitrogen element and a bromine element, the sum of the phosphorus element and the nitrogen element accounts for 60wt%-80wt% of the total mass of all the flame-retardant elements, and the bromine element accounts for 15wt%-30wt% of the total mass of all the flame-retardant elements; the mass ratio of the phosphorus element to the nitrogen element is less than or equal to 3: 1. By regulating and controlling the proportions of bromine, phosphorus and nitrogen in the flame retardant, the flame-retardant elements play a synergistic flame-retardant role, and the aluminum foil reinforced polyolefin foam with low smoke, fire resistance and heat resistance is obtained.

Description

Technical Field

[0001] The present application belongs to the field of polymer materials, and more specifically, relates to low-smoke, fire-proof and heat-resistant aluminum foil reinforced polyolefin foam, a preparation method and an application thereof. Background Art

[0002] Polyolefin foam is widely used in rail transit due to its light weight, excellent thermal insulation, electrical insulation and good chemical stability. However, when conventional polyolefin foam encounters flame combustion, it will produce a lot of smoke. At the same time, the heat diffuses quickly during combustion, and the flame can easily penetrate the polyolefin foam. The poor temperature resistance and combustion characteristics limit the application of polyolefin foam in rail transit.

[0003] The compounding of polyolefin foam and aluminum foil can effectively improve the temperature resistance and combustion characteristics of polyolefin foam. Conventional aluminum foil and polyolefin foam are bonded together by double-sided tape. When a fire occurs, the middle adhesive layer is easy to decompose, resulting in the separation of aluminum foil and polyolefin foam. The polyolefin foam is exposed to open flames and cannot effectively play a protective role. At the same time, the burning of the adhesive layer will produce a lot of smoke and release toxic gases, causing great harm. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of this application is to provide low-smoke, fire-resistant and heat-resistant aluminum foil reinforced polyolefin foam, a preparation method and application, aiming to solve the technical problems of the existing aluminum foil composite polyolefin foam, such as poor adhesion between the aluminum foil and the polyolefin foam during high-temperature combustion, easy separation, and generation of a large amount of toxic gases, and failure to meet the requirements of low smoke, fire resistance and heat resistance.

[0005] To achieve the above object, the present application provides a low-smoke, fire-proof and heat-resistant aluminum foil reinforced polyolefin foam, which includes polyolefin foam and an aluminum foil structure arranged on the surface of the polyolefin foam; the polyolefin foam is foamed by polyolefin resin, flame retardant, foaming agent, adhesive and auxiliary agent; the aluminum foil structure includes an aluminum foil layer;

[0006] The flame retardant comprises phosphorus, nitrogen and bromine, wherein the sum of phosphorus and nitrogen accounts for 60wt% to 80wt% of the total mass of all flame retardant elements, and bromine accounts for 15wt% to 30wt% of the total mass of all flame retardant elements; and the mass ratio of phosphorus to nitrogen is less than or equal to 3:1.

[0007] Preferably, in the flame retardant, the mass ratio of phosphorus element to nitrogen element is (1-3):1.

[0008] Further preferably, the flame retardant further comprises other elements, and the other elements account for 0wt% to 20wt% of the total mass of all flame retardant elements; the other elements are selected from one or more of aluminum, magnesium and antimony.

[0009] Preferably, the mass ratio of the polyolefin resin, flame retardant, foaming agent, adhesive and auxiliary agent is (50-200):(1-30):(10-20):(5-20):(1-10).

[0010] Preferably, the thickness of the aluminum foil layer is 0.05-1 mm.

[0011] Preferably, the aluminum foil structure further includes a functional coating and / or reinforcing ribs.

[0012] Preferably, the pore size of the polyolefin foam is 100-600 μm, and the density is 25-200 kg / m 3 , and the ratio of pore diameter to density is less than or equal to 10:1.

[0013] Further preferably, the ratio of the cell diameter to the density of the polyolefin foam is (3-10):1.

[0014] Preferably, the critical thermal radiation value of the aluminum foil reinforced polyolefin foam is 50 kW / m 2 The maximum average heat release rate is less than 20kW / m 2 , VOF4 is less than 200, the maximum specific optical density value within 10 minutes is less than 150, and the average toxicity index is less than 1.

[0015] Further preferably, after the aluminum foil reinforced polyolefin foam is burned with a 600° C. flame for 3 minutes, the polyolefin foam and the aluminum foil structure are not separated.

[0016] Preferably, the density of the polyolefin resin is 0.88 to 0.97 g / cm 3 , selected from one or more of low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, copolymer polypropylene and homopolypropylene.

[0017] Preferably, the median particle size of the flame retardant is 1 to 100 μm, more preferably 7 to 40 μm.

[0018] Preferably, the gas evolution amount of the foaming agent is 220-300 mL / g, and the median particle size is 1-50 μm. More preferably, the gas evolution amount of the foaming agent is 220-240 mL / g, and the median particle size is 14-20 μm.

[0019] Preferably, the adhesive is one or more of ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer and aluminate coupling agent.

[0020] Preferably, the mass percentage of acrylic acid in the above ethylene-acrylic acid copolymer is 9% to 20%.

[0021] Preferably, the mass percentage of methyl acrylate in the above ethylene-methyl acrylate copolymer is 9% to 30%.

[0022] Preferably, the auxiliary agent includes one or more of an antioxidant, a dispersant and a sensitizer.

[0023] On the other hand, the present application also provides a method for preparing the above-mentioned aluminum foil reinforced polyolefin foam, comprising the following steps:

[0024] S1, mixing and granulating the polyolefin resin, adhesive, foaming agent, flame retardant and additive according to the ratio to obtain full-formula particles, and then extruding the full-formula particles to obtain a substrate;

[0025] S2, irradiating and cross-linking the substrate to obtain a master sheet, and then foaming the master sheet to obtain a foamed sheet;

[0026] S3, placing the above aluminum foil structure on the above foamed sheet, and subjecting it to a thermal composite process to obtain aluminum foil reinforced polyolefin foam.

[0027] Preferably, in step S2, the electron energy of the radiation cross-linking is 0.1-4.0 MeV, the dose of the radiation cross-linking is 3-50 Mrad, and the cross-linking degree of the substrate is controlled to be 25%-60%.

[0028] Preferably, in step S2, the foaming temperature is 180°C to 300°C.

[0029] Preferably, in step S3, the thermal bonding process is at least one of hot air bonding and hot pressing bonding.

[0030] Preferably, the specific operation of the hot air compounding is: placing the aluminum foil structure on the foam sheet, and then passing hot air at 200° C. to 250° C. for compounding.

[0031] Preferably, the specific operation of the above-mentioned hot pressing composite is: placing the above-mentioned aluminum foil structure on the above-mentioned foam sheet, and composite it through a roller at 150°C to 250°C.

[0032] The present application also provides a fireproof material for rail transit, which includes the above-mentioned aluminum foil reinforced polyolefin foam.

[0033] In general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art:

[0034] (1) The low-smoke, fire-proof and heat-resistant aluminum foil reinforced polyolefin foam provided in the present application includes polyolefin foam and an aluminum foil structure arranged on the surface of the polyolefin foam; wherein the polyolefin foam is foamed by polyolefin resin, flame retardant, foaming agent, adhesive and auxiliary agent; the aluminum foil structure includes an aluminum foil layer. The above-mentioned flame retardant includes bromine, phosphorus and nitrogen, wherein the sum of phosphorus and nitrogen accounts for 60wt% to 80wt% of the total mass of all flame retardant elements, and bromine accounts for 15wt% to 30wt% of the total mass of all flame retardant elements; and the mass ratio of phosphorus to nitrogen is less than or equal to 3:1. By adjusting the proportion of bromine, phosphorus and nitrogen in the flame retardant, the flame retardant elements play a synergistic flame retardant role, and an aluminum foil reinforced polyolefin foam with low smoke, fire resistance and heat resistance is obtained, which is suitable for the field of rail transportation.

[0035] (2) The present application adjusts the mass fractions of flame retardants and adhesives, as well as the types and proportions of flame retardant elements, so as to exert the synergistic flame retardant effect between the flame retardant elements, reduce the amount of smoke during combustion, and improve the overall flame retardant uniformity, and improve the low smoke, fire resistance, and heat resistance of the foam. In addition, by regulating the mass fractions of polyolefin resin and foaming agent in the polyolefin foam, and then regulating the pore size, density, and ratio of pore size to density of the foam, the contact area between the polyolefin foam and the aluminum foil structure is increased, and the bonding performance of the foam and the aluminum foil structure is improved. Through process adjustment, an aluminum foil-reinforced polyolefin foam with good bonding between the foam and the aluminum foil and low smoke, fire resistance, and heat resistance is prepared. In addition, the preparation method provided by the present application has a simple process and low processing difficulty, and can be mass-produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a graph showing the adhesion test results of the aluminum foil reinforced polyolefin foam prepared in Example 2;

[0037] Figure 2 This is a graph showing the adhesion test results of the aluminum foil reinforced polyolefin foam prepared in Comparative Example 4. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present application more clear, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0039] The present application provides a low-smoke, fire-proof and heat-resistant aluminum foil reinforced polyolefin foam, which comprises a polyolefin foam and an aluminum foil structure arranged on the surface of the polyolefin foam; the polyolefin foam is foamed by a polyolefin resin, a flame retardant, a foaming agent, an adhesive and an auxiliary agent; the aluminum foil structure comprises an aluminum foil layer;

[0040] The flame retardant comprises phosphorus, nitrogen and bromine, wherein the sum of phosphorus and nitrogen accounts for 60wt% to 80wt% of the total mass of all flame retardant elements, and bromine accounts for 15wt% to 30wt% of the total mass of all flame retardant elements; and the mass ratio of phosphorus to nitrogen is less than or equal to 3:1.

[0041] The present application can coordinately regulate the smoke density and flame retardant effect of foam combustion by regulating the proportion of bromine, phosphorus and nitrogen in the flame retardant, wherein the amount of bromine in the flame retardant is small, which can reduce the smoke density, corrosive and toxic gases released when the overall material is burned, and the generated hydrogen bromide gas can isolate the contact between the foam material and oxygen, thereby improving the flame retardant efficiency. Flame retardants containing phosphorus or nitrogen have a high melting point, can absorb heat by melting, isolate the fire source, and reduce the speed of flame spread. At the same time, phosphorus and nitrogen can react with oxygen to generate phosphoric acid, potassium hydrogen phosphate, nitrogen and nitric oxide, etc., thereby reducing the flame temperature and thermal radiation intensity, and slowing down the chemical reaction rate; in addition, phosphorus can also generate polymetaphosphoric acid, which covers the surface of the combustion body to form a protective film, isolates the contact between the material and the air, and reduces the degree of flame delay. The generated polymetaphosphoric acid is a strong acid with strong dehydration, which can dehydrate the polymer and carbonize it, and form a carbonized layer on its surface to isolate the inside of the polymer from the air and prevent combustion. Combining the above effects, the present application can achieve excellent flame retardant effect with a low amount of flame retardant added. Compared with existing foams, it can significantly reduce the difficulty of foam production and reduce production costs.

[0042] In some embodiments, the mass ratio of phosphorus to nitrogen in the flame retardant is (1-3):1. The bromine and nitrogen in the flame retardant of the present application can reduce the concentration of oxygen and combustible gas and reduce the necessary conditions for combustion through the mechanism of gas phase flame retardancy. At the same time, phosphorus can accelerate the carbonization of polymers through the mechanism of condensed phase flame retardancy to form a carbonized layer, protect the polymer under the carbonized layer from the fire source, and control the proportion of flame retardant elements and the ratio of phosphorus to nitrogen. The bromine, phosphorus, and nitrogen elements play a synergistic flame retardant role, thereby improving the low smoke, flame retardant, and heat resistant properties of the foam. When the ratio of phosphorus to nitrogen in the flame retardant is too large, such as 4:1, the synergistic flame retardancy between the flame retardant components deteriorates, which ultimately leads to the deterioration of the low smoke, fire retardant, and heat resistant properties of the foam.

[0043] In some embodiments, the mass ratio of the polyolefin resin, flame retardant, foaming agent, adhesive and additive is (50-200):(1-30):(10-20):(5-20):(1-10).

[0044] In some embodiments, the mass ratio of the polyolefin resin, flame retardant, foaming agent, adhesive and additive is (50-200):(5-20):(10-20):(5-20):(1-5).

[0045] In some embodiments, the polyolefin foam has a thickness of 2 to 10 mm.

[0046] In some embodiments, the thickness of the aluminum foil layer is 0.05-1 mm, preferably 0.05-0.2 mm.

[0047] In some embodiments, the aluminum foil structure further includes at least one of a functional coating and a reinforcing rib. When the aluminum foil structure is an aluminum foil layer and a functional coating, the functional coating is located on the outside of the aluminum foil reinforced polyolefin foam, that is, the structure of the aluminum foil reinforced polyolefin foam is a polyolefin foam, an aluminum foil layer and a functional coating arranged in sequence. When the aluminum foil structure is a reinforcing rib and an aluminum foil layer, the reinforcing rib is located between the polyolefin foam and the aluminum foil layer, that is, the structure of the aluminum foil reinforced polyolefin foam is a polyolefin foam, a reinforcing rib and an aluminum foil layer arranged in sequence. It is to be understood that the present application does not limit the type and thickness of the functional coating and the reinforcing rib, and those skilled in the art can select according to actual application requirements. In some embodiments, the functional coating includes but is not limited to an anti-UV coating, and the reinforcing rib includes but is not limited to a glass fiber reinforcement layer.

[0048] The polyolefin foam prepared by the synergistic effect of the components in the formula has a pore size of 150 to 250 μm and a density of 25 to 60 kg / m 3 , and the ratio of cell diameter to density is less than or equal to 10:1. The critical thermal radiation value (CFE) of the above aluminum foil reinforced polyolefin foam is 50kW / m 2 , the maximum average heat release rate (HRR) is less than 20kW / m 2 The cumulative optical density value (VOF4) before the test is less than 200, and the maximum specific optical density value (Ds max ) is less than 150, and the average toxicity index (CITG) is less than 1.

[0049] In some embodiments, in the polyolefin foam, the ratio of the pore size to the density is (3-10):1.

[0050] In some embodiments, after the aluminum foil reinforced polyolefin foam is burned with a 600° C. flame for 3 minutes, the polyolefin foam and the aluminum foil structure are not separated.

[0051] In some embodiments, the density of the polyolefin resin is 0.88-0.97 g / cm 3The present application does not limit the specific types of the above-mentioned polyolefin resins, including but not limited to one or more of low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, copolymer polypropylene and homopolymer polypropylene.

[0052] In a preferred embodiment, the flame retardant further comprises other elements, and the other elements account for 0wt% to 20wt% of the total mass of all flame retardant elements; the other elements are selected from one or more of aluminum, magnesium and antimony.

[0053] In some embodiments, the median particle size of the flame retardant is 1 to 100 μm, preferably 7 to 40 μm.

[0054] The present application does not specifically limit the types of the above-mentioned foaming agents, and preferably the foaming agents with low cost and good foaming effect are selected, such as but not limited to one or more of azodicarbonamide, OBSH foaming agent, N,N'-dinitrosopentamethylenetetramine, 4,4-oxobisbenzenesulfonylhydrazine, inorganic carbonates and bicarbonates. In some embodiments, the gas emission of the above-mentioned foaming agent is 220-300 mL / g, and the median particle size is 1-50 μm, preferably, the gas emission is 220-240 mL / g, and the median particle size is 14-20 μm.

[0055] In some embodiments, the ratio of the median particle size of the flame retardant to the median particle size of the foaming agent is (0.5-2): 1. By controlling the particle size ratio to the particle size of the foaming agent, the flame retardant and the foaming agent can be evenly dispersed. In the foaming stage, the flame retardant can play a role in heterogeneous nucleation and can serve as the starting point of the foaming cells. The generated cells are uniform and will not show anisotropy during combustion, which is conducive to improving the overall flame retardant uniformity and flame retardant effect.

[0056] In some embodiments, the adhesive is one or more of ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer, and aluminate coupling agent.

[0057] In some embodiments, the mass percentage of acrylic acid in the above ethylene-acrylic acid copolymer is 9% to 20%. In some embodiments, the mass percentage of methyl acrylate in the above ethylene-methyl acrylate copolymer is 9% to 30%.

[0058] In order to meet the requirements of different application environments, the aluminum foil reinforced polyolefin foam prepared in the present application also includes 1 to 5 parts by mass of an auxiliary agent to give the foam various properties. The above-mentioned auxiliary agent includes but is not limited to one or more of an antioxidant, a dispersant and a sensitizer. It is understood that the present application does not limit the specific types of the above-mentioned antioxidant, dispersant and sensitizer, and those skilled in the art can select a suitable auxiliary agent according to actual needs.

[0059] The present application provides a method for preparing the above-mentioned aluminum foil reinforced polyolefin foam, comprising the following steps:

[0060] S1, mixing and granulating the polyolefin resin, adhesive, foaming agent and auxiliary agent according to the ratio to obtain full-formula particles, and then extruding the full-formula particles to obtain a substrate;

[0061] S2, irradiating and cross-linking the substrate to obtain a master sheet, and then foaming the master sheet to obtain a foamed sheet;

[0062] S3, placing the above aluminum foil structure on the above foamed sheet, and subjecting it to a thermal composite process to obtain aluminum foil reinforced polyolefin foam.

[0063] In order to improve the dispersion uniformity of each raw material, in some embodiments, the above step S1 is as follows: all the foaming agents are mixed and granulated with a part of the mass fraction of polyolefin resin, adhesive and auxiliary agent to obtain foaming agent masterbatch; all the flame retardants are mixed and granulated with the remaining mass fraction of polyolefin resin, adhesive and auxiliary agent to obtain flame retardant masterbatch; then the above foaming agent masterbatch and flame retardant masterbatch are stirred and mixed and then granulated to obtain full formula particles, and then the above full formula particles are extruded to obtain substrates.

[0064] It is understandable that the present application does not limit the process of the internal mixing and blending in step S1, as long as the materials can be evenly dispersed.

[0065] In some embodiments, in step S2, the electron energy of the radiation cross-linking is 0.1-4.0 MeV, the dose of the radiation cross-linking is 3-50 Mrad, and the cross-linking degree of the substrate is controlled to be 25%-60%.

[0066] In some embodiments, in step S2, the foaming temperature is 180°C to 300°C;

[0067] In some embodiments, in step S3, the thermal bonding process is at least one of hot air bonding and hot pressing bonding.

[0068] In some embodiments, the specific operation of the hot air compounding is: placing the aluminum foil structure on the foam sheet, and then passing hot air at 200° C. to 250° C. for compounding.

[0069] In some embodiments, the specific operation of the hot pressing composite is: placing the aluminum foil structure on the foam sheet, and composite it with a roller at 150° C. to 250° C.

[0070] The present application also provides a fireproof material for rail transit, which includes the above-mentioned aluminum foil reinforced polyolefin foam.

[0071] It should be understood that materials with the same or similar types, models, qualities, properties or functions as the reagents and instruments used in the following examples can be used to implement the present application. The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

[0072] The following are examples and comparative examples:

[0073] Example 1

[0074] The components and weight fractions of the aluminum foil reinforced polyolefin foam of this embodiment are shown in Table 1.

[0075] Table 1 Composition of the aluminum foil reinforced polyolefin foam of Example 1

[0076]

[0077] The preparation steps of the aluminum foil reinforced polyolefin foam provided in this embodiment are as follows:

[0078] (1) Foaming agent masterbatch: 50% by weight of polyolefin resin, adhesive, additive and all foaming agents are put into an internal mixer for mixing and kneading. The temperature of the internal mixer is 115° C. and the kneading time is 15 min. Then the mixture is discharged into a pelletizer for granulation to obtain a foaming agent masterbatch.

[0079] (2) Flame retardant masterbatch: The remaining polyolefin resin, adhesive, additive and all flame retardants are put into an internal mixer for mixing and kneading. The temperature of the internal mixer is 150°C and the kneading time is 20 minutes. Then, the mixture is discharged into a pelletizer for granulation to obtain a flame retardant masterbatch.

[0080] (3) Base sheet: The foaming agent masterbatch of step (1) and the flame retardant masterbatch of step (2) are stirred and mixed at room temperature at a speed of 60 r / min for 60 min, and then put into a twin-screw extruder for granulation to obtain full-formula particles; and then the full-formula particles are extruded using a single-screw extruder to obtain a base sheet.

[0081] (4) Foamed sheet: The substrate was subjected to electron irradiation cross-linking, the electron energy of the irradiation cross-linking was 2.0 MeV, the irradiation dose was 25 Mrad, and the cross-linking degree of the substrate was controlled to be 55%, thereby obtaining a master sheet; the master sheet was subjected to free-style foaming at a foaming temperature of 230° C., thereby obtaining a 5 mm foamed sheet.

[0082] (5) Covering the aluminum foil structure on the foamed sheet in step (4), and subjecting the composite material to hot pressing with rollers at a temperature of 180° C., to obtain aluminum foil reinforced polyolefin foam P1.

[0083] Example 2

[0084] The components and weight fractions of the aluminum foil reinforced polyolefin foam of this embodiment are shown in Table 2.

[0085] Table 2 Composition of the aluminum foil reinforced polyolefin foam of Example 2

[0086]

[0087] The preparation steps of the aluminum foil reinforced polyolefin foam provided in this embodiment are as follows:

[0088] The preparation of foaming agent masterbatch, flame retardant masterbatch and substrate is the same as that in Example 1. The substrate is subjected to electron irradiation crosslinking, the electron energy of the irradiation crosslinking is 4.0 MeV, the irradiation dose is 10 Mrad, and the crosslinking degree of the substrate is controlled to be 60%, to obtain a master sheet; the master sheet is subjected to free-style foaming, the foaming temperature is 200°C, to obtain a 3 mm foam sheet. The aluminum foil structure is covered on the foam sheet, and hot air at 230°C is introduced for hot air compounding to obtain aluminum foil reinforced polyolefin foam P2.

[0089] Example 3

[0090] The components and weight fractions of the aluminum foil reinforced polyolefin foam of this embodiment are shown in Table 3.

[0091] Table 3 Composition of the aluminum foil reinforced polyolefin foam of Example 3

[0092]

[0093] The preparation steps of the aluminum foil reinforced polyolefin foam provided in this embodiment are as follows:

[0094] The preparation of foaming agent masterbatch, flame retardant masterbatch and substrate is the same as that in Example 1. The substrate is subjected to electron irradiation crosslinking, the electron energy of the irradiation crosslinking is 2.0 MeV, the irradiation dose is 15 Mrad, and the crosslinking degree of the substrate is controlled to be 50%, to obtain a master sheet; the master sheet is subjected to free-style foaming, the foaming temperature is 220°C, to obtain a 10 mm foam sheet. The aluminum foil structure is covered on the foam sheet, and hot-pressed and compounded by rollers at a temperature of 180°C to obtain aluminum foil reinforced polyolefin foam P3.

[0095] Example 4

[0096] The components and weight fractions of the aluminum foil reinforced polyolefin foam of this embodiment are shown in Table 4.

[0097] Table 4 Composition of the aluminum foil reinforced polyolefin foam of Example 4

[0098]

[0099] The preparation steps of the aluminum foil reinforced polyolefin foam provided in this embodiment are as follows:

[0100] The preparation of foaming agent masterbatch, flame retardant masterbatch and substrate is the same as that in Example 1. The substrate is subjected to electron irradiation crosslinking, the electron energy of the irradiation crosslinking is 4.0 MeV, the irradiation dose is 20 Mrad, and the crosslinking degree of the substrate is controlled to be 57%, to obtain a master sheet; the master sheet is subjected to free-style foaming, the foaming temperature is 200°C, to obtain a 7mm foamed sheet. The aluminum foil structure is covered on the foamed sheet, and hot-pressed and compounded by rollers at a temperature of 170°C to obtain aluminum foil reinforced polyolefin foam P4.

[0101] Example 5

[0102] The components and weight fractions of the aluminum foil reinforced polyolefin foam of this embodiment are shown in Table 5.

[0103] Table 5 Composition of the aluminum foil reinforced polyolefin foam of Example 5

[0104]

[0105]

[0106] The preparation steps of the aluminum foil reinforced polyolefin foam provided in this embodiment are as follows:

[0107] The preparation of foaming agent masterbatch, flame retardant masterbatch and substrate is the same as that in Example 1. The substrate is subjected to electron irradiation crosslinking, the electron energy of the irradiation crosslinking is 2.0 MeV, the irradiation dose is 15 Mrad, and the crosslinking degree of the substrate is controlled to be 48%, to obtain a master sheet; the master sheet is subjected to free-style foaming, the foaming temperature is 190°C, to obtain a 4 mm foam sheet. The aluminum foil structure is covered on the foam sheet, and hot air at 200°C is introduced for hot air compounding to obtain aluminum foil reinforced polyolefin foam P5.

[0108] Example 6

[0109] The components and mass fractions of the aluminum foil reinforced polyolefin foam of this embodiment are shown in Table 6.

[0110] Table 6 Composition of the aluminum foil reinforced polyolefin foam of Example 6

[0111]

[0112]

[0113] The preparation steps of the aluminum foil reinforced polyolefin foam provided in this embodiment are as follows:

[0114] The preparation of foaming agent masterbatch, flame retardant masterbatch and substrate is the same as in Example 1. The substrate is subjected to electron irradiation crosslinking, the electron energy of the irradiation crosslinking is 3.0 MeV, the irradiation dose is 15 Mrad, and the crosslinking degree of the substrate is controlled to be 55%, to obtain a master sheet; the master sheet is subjected to free-style foaming, the foaming temperature is 220°C, to obtain a 3mm foamed sheet. The aluminum foil structure is covered on the foamed sheet, and hot-pressed and compounded by rollers at a temperature of 200°C to obtain aluminum foil reinforced polyolefin foam P6.

[0115] Example 7

[0116] The components and weight fractions of the aluminum foil reinforced polyolefin foam of this embodiment are shown in Table 7.

[0117] Table 7 Composition of the aluminum foil reinforced polyolefin foam of Example 7

[0118]

[0119] The preparation steps of the aluminum foil reinforced polyolefin foam provided in this embodiment are as follows:

[0120] The preparation of foaming agent masterbatch, flame retardant masterbatch and substrate is the same as that in Example 1. The substrate is subjected to electron irradiation crosslinking, the electron energy of the irradiation crosslinking is 2.0 MeV, the irradiation dose is 10 Mrad, and the crosslinking degree of the substrate is controlled to be 47%, to obtain a master sheet; the master sheet is subjected to free-style foaming, the foaming temperature is 190°C, to obtain a 3 mm foamed sheet. The aluminum foil structure is covered on the foamed sheet, and hot-pressed and compounded by rollers at a temperature of 200°C to obtain aluminum foil reinforced polyolefin foam P7.

[0121] Example 8

[0122] The components and mass fractions of the aluminum foil reinforced polyolefin foam of this embodiment are shown in Table 8.

[0123] Table 8 Composition of the aluminum foil reinforced polyolefin foam of Example 8

[0124]

[0125] The preparation steps of the aluminum foil reinforced polyolefin foam provided in this embodiment are as follows:

[0126] The preparation of foaming agent masterbatch, flame retardant masterbatch, base sheet and master sheet is the same as in Example 1. The master sheet is subjected to free-style foaming at a foaming temperature of 210°C to obtain a 5 mm foam sheet. The aluminum foil structure is covered on the foam sheet and hot-pressed and laminated by rollers at a temperature of 180°C to obtain aluminum foil reinforced polyolefin foam P8.

[0127] Comparative Example 1

[0128] The components and weight fractions of the polyolefin foam of this comparative example are shown in Table 9.

[0129] Table 9 Composition of the polyolefin foam of Comparative Example 1

[0130]

[0131]

[0132] The preparation method of the polyolefin foam provided in this comparative example is the same as that in Example 1, wherein the crosslinking degree of the base sheet is 52%, and the prepared 5 mm foam sheet is polyolefin foam D1.

[0133] Comparative Example 2

[0134] An aluminum foil structure is covered on the foam sheet prepared in Comparative Example 1, wherein the aluminum foil structure is aluminum foil + glass fiber reinforcement layer, the thickness of the aluminum foil is 0.1 mm, and the thickness of the glass fiber reinforcement layer is 0.02 mm. Then, the method of Example 1 is used to prepare aluminum foil reinforced polyolefin foam D2.

[0135] Comparative Example 3

[0136] The polyolefin foam of this comparative example does not include an aluminum foil structure, and other parameters are the same as those of Example 2. Then, a foamed sheet, namely, polyolefin foam D3, is prepared according to the method of Example 2.

[0137] Comparative Example 4

[0138] The adhesive of the aluminum foil reinforced polyolefin foam of this comparative example is 3 parts of ethylene-acrylic acid copolymer and 1 part of aluminate coupling agent, and other parameters are the same as those of Example 2.

[0139] The preparation method of the aluminum foil reinforced polyolefin foam provided in this comparative example is as follows:

[0140] The preparation of foaming agent masterbatch, flame retardant masterbatch, base sheet, master sheet and foaming sheet is the same as in Example 2. The aluminum foil structure and the foaming sheet are bonded with an adhesive, and then hot air compounded according to the method of Example 2 to obtain aluminum foil reinforced polyolefin foam D4.

[0141] Comparative Example 5

[0142] The components and weight fractions of the aluminum foil reinforced polyolefin foam of this comparative example are shown in Table 10.

[0143] Table 10 Composition of the aluminum foil reinforced polyolefin foam of Comparative Example 5

[0144]

[0145]

[0146] The preparation method of the aluminum foil reinforced polyolefin foam D5 of this comparative example is the same as that of Example 2.

[0147] The performance test of the products prepared in Examples 1 to 8 and Comparative Examples 1 to 5 was conducted by the following test methods:

[0148] (1) Cell diameter of foam: 5 specimens with a size of 100 mm × 50 mm (length × width) were cut from the foam sheet, placed in liquid nitrogen for 30 min and then taken out. The specimens were broken in the middle to obtain 10 specimens with fracture surfaces. The fracture surface of each specimen was taken with an electron microscope at 200 times magnification. Two positions were selected on each fracture surface, and the size of each position was 2 mm × 2 mm. The pore diameters of all micropores at the above positions were measured, and the arithmetic mean of the pore diameters was taken as the cell diameter.

[0149] (2) Foam density: tested according to JIS K6767 (1999) "Foamed plastics - Polyethylene - Test methods".

[0150] (3) Critical thermal radiation (CFE): Refer to ISO 5660-1 standard test.

[0151] (4) Maximum average heat release rate (HRR): Refer to ISO 5660-1 standard (heat radiation level is set to 50kw / m 2 )test.

[0152] (5) The cumulative optical density value (VOF4) in the first 4 minutes of the test, the maximum specific optical density value (Ds max ), Toxicity index CITG average value: refer to ISO 5659-2 standard test.

[0153] (6) Adhesion test: Cut the product into 15cm×15cm sheets, use 600℃ ethane flame to burn the aluminum foil surface for 3min, then remove the flame and wait for cooling, peel off the foam and aluminum foil, and observe whether the aluminum foil surface is adhered to the foam. If the aluminum foil surface is adhered to the foam, it means that the foam and aluminum foil are not separated, and the adhesion is good; if the aluminum foil surface is not adhered to the foam, it means that the foam and aluminum foil are separated, and the adhesion is poor.

[0154] The test results are shown in Tables 11 and 12.

[0155] Table 11 Properties of aluminum foil reinforced polyolefin foams P1 to P8 prepared in Examples 1 to 8

[0156]

[0157] Table 12 Properties of polyolefin foams D1 to D5 prepared in Comparative Examples 1 to 5

[0158]

[0159] The experimental results show that from the perspective of formula preparation and process improvement, this application coordinates the flame retardant properties of the foam, the bonding properties of the foam and the aluminum foil structure by adjusting the ratio of pores and density, the amount of adhesive, the proportion of flame retardant elements bromine, phosphorus and nitrogen, the ratio of phosphorus and nitrogen, the particle size of the foaming agent and the flame retardant, etc., to play a synergistic flame retardant role, reduce the amount of smoke during combustion, and at the same time, effectively improve the flame retardant uniformity of the entire foam. In addition, it can ensure that the aluminum foil structure and the foam do not separate during high-temperature combustion, thereby improving the temperature resistance and combustion characteristics of the foam, and can also effectively support the foam structure, slow down the combustion rate of the foam, and further reduce the concentration of smoke released to the outside world. The critical thermal radiation value (CFE) of the aluminum foil reinforced polyolefin foam prepared in this application is 50kW / m 2 , the maximum average heat release rate (HRR) is less than 20kW / m 2 The cumulative optical density value (VOF4) of the first 4 minutes of the test is less than 200, and the maximum specific optical density value (Ds max ) is less than 150, the average toxicity index CITG is less than 1, the foam and aluminum foil structure do not separate when burned at a high temperature of 600°C, the bonding performance is good, and it can be used in rail transit scenarios such as railway carriages.

[0160] The foam of Comparative Example 1 does not contain an aluminum foil structure, and the flame retardant in the foam formula does not contain phosphorus and nitrogen elements. When the prepared foam is subjected to a critical thermal radiation value (CFE) test, the foam is completely thermally decomposed, and there is no phenomenon of the flame stopping propagation and extinguishing, indicating that the flame retardant performance of the foam is poor. Comparative Example 2 adds an aluminum foil structure through a thermal composite process on the basis of Comparative Example 1, but the combustion characteristics of the foam are still poor, and do not meet the requirements of low smoke, fire resistance and heat resistance, and are not suitable for rail transit scenarios. Example 1 of the present application synergistically improves the temperature resistance and combustion characteristics of the foam, and the bonding performance of the foam and the aluminum foil structure by adjusting the formula and structure of the foam.

[0161] In Example 2 of the present application, the foam formula and process are improved by coordinated regulation, so that the foam and the aluminum foil structure will not separate during high temperature combustion (such as Figure 1 As shown), it has excellent low smoke fireproof and heat resistant performance. Compared with Example 2, the foam prepared in Comparative Example 3 does not contain an aluminum foil structure, and the low smoke fireproof and heat resistant performance of the prepared foam is poor. Comparative Example 4 reduces the amount of adhesive on the basis of Comparative Example 3, and uses an adhesive and a thermal composite process to composite an aluminum foil structure. The low smoke fireproof and heat resistant performance of the prepared foam is slightly better than that of Comparative Example 3, but it still does not meet the requirements of the application scenario, and the foam and the aluminum foil structure separate during high temperature combustion (such as Figure 2 The bonding performance is poor.

[0162] When the foam prepared in Comparative Example 5 is burned at high temperature, the foam and the aluminum foil structure separate. The possible reason is that the ratio of pore size and density is too large, the contact area between the foam and the aluminum foil structure is reduced, thereby reducing the bonding performance. At the same time, the ratio of phosphorus and nitrogen in the flame retardant is too large, and the synergistic flame retardancy between the flame retardant components deteriorates, which ultimately leads to the deterioration of the low-smoke fire retardancy and heat resistance of the foam.

[0163] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. Low smoke, fireproof and heat-resistant aluminum foil reinforced polyolefin foam, characterized in that: It includes polyolefin foam and an aluminum foil structure arranged on the surface of the polyolefin foam; the polyolefin foam is foamed by polyolefin resin, flame retardant, foaming agent, adhesive and auxiliary agent; the aluminum foil structure includes an aluminum foil layer; The flame retardant comprises phosphorus, nitrogen and bromine, wherein the sum of phosphorus and nitrogen accounts for 60wt% to 80wt% of the total mass of all flame retardant elements, and bromine accounts for 15wt% to 30wt% of the total mass of all flame retardant elements; and the mass ratio of phosphorus to nitrogen is less than or equal to 3:

1.

2. The aluminum foil reinforced polyolefin foam according to claim 1, characterized in that: The mass ratio of the polyolefin resin, the flame retardant, the foaming agent, the adhesive and the auxiliary agent is (50-200):(1-30):(10-20):(5-20):(1-10).

3. The aluminum foil reinforced polyolefin foam according to claim 1, characterized in that: The thickness of the aluminum foil layer is 0.05-1 mm; the aluminum foil structure also includes a functional coating and / or reinforcing ribs.

4. The aluminum foil reinforced polyolefin foam according to any one of claims 1 to 3, characterized in that: The pore diameter of the polyolefin foam is 100-600 μm, and the density is 25-200 kg / m 3 , and the ratio of pore diameter to density is less than or equal to 10:1; The critical thermal radiation value of the aluminum foil reinforced polyolefin foam is 50kW / m 2 The maximum average heat release rate is less than 20kW / m 2 , VOF4 is less than 200, the maximum specific optical density value within 10 minutes is less than 150, and the average toxicity index is less than 1; Preferably, after the aluminum foil reinforced polyolefin foam is burned with a 600° C. flame for 3 minutes, the polyolefin foam and the aluminum foil structure are not separated.

5. The aluminum foil reinforced polyolefin foam according to claim 1, characterized in that: The density of the polyolefin resin is 0.88-0.97 g / cm 3 , selected from one or more of low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ultra-high molecular weight polyethylene, copolymer polypropylene and homopolypropylene.

6. The aluminum foil reinforced polyolefin foam according to claim 1, characterized in that: The flame retardant has a median particle size of 1 to 100 μm; and / or, The foaming agent has a gas emission of 220 to 300 mL / g and a median particle size of 1 to 50 μm; and / or, The adhesive is one or more of ethylene-acrylic acid copolymer, ethylene-methyl acrylate copolymer and aluminate coupling agent; and / or, The auxiliary agent includes one or more of an antioxidant, a dispersant and a sensitizer.

7. The aluminum foil reinforced polyolefin foam according to claim 6, characterized in that: The flame retardant further comprises other elements, which account for 0wt% to 20wt% of the total mass of all flame retardant elements and are selected from one or more of aluminum, magnesium and antimony; and / or, The flame retardant has a median particle size of 7 to 40 μm; and / or, The foaming agent has a gas emission of 220 to 240 mL / g and a median particle size of 14 to 20 μm; and / or The mass percentage of acrylic acid in the ethylene-acrylic acid copolymer is 9% to 20%; and / or, The mass percentage of methyl acrylate in the ethylene-methyl acrylate copolymer is 9% to 30%.

8. A method for preparing the aluminum foil reinforced polyolefin foam according to any one of claims 1 to 7, characterized in that: The steps include: S1, mixing and granulating the polyolefin resin, adhesive, foaming agent, flame retardant and additive according to the ratio to obtain full-formula particles, and then extruding the full-formula particles to obtain a substrate; S2, irradiating and cross-linking the substrate to obtain a master sheet, and then foaming the master sheet to obtain a foamed sheet; S3, placing the aluminum foil structure on the foamed sheet, and subjecting it to a thermal composite process to obtain aluminum foil reinforced polyolefin foam.

9. The preparation method according to claim 8, characterized in that: In step S2, the electron energy of the radiation cross-linking is 0.1-4.0 MeV, the radiation cross-linking dose is 3-50 Mrad, and the cross-linking degree of the substrate is controlled to be 25%-60%; the foaming temperature is 180° C.-300° C.; In step S3, the thermal bonding process is at least one of hot air bonding and hot pressing bonding; The specific operation of the hot air compounding is: placing the aluminum foil structure on the foam sheet, and then passing hot air at 200° C. to 250° C. for compounding; The specific operation of the hot pressing composite is: placing the aluminum foil structure on the foam sheet, and composite it through a roller at 150° C. to 250° C.

10. A fireproof material for rail transit, characterized in that: The invention comprises the aluminum foil reinforced polyolefin foam as described in any one of claims 1 to 7.

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