Low smoke fire retardant heat resistant aluminum foil reinforced polyolefin foam, method of making and use

Abstract

The application belongs to the field of polymer materials, and more particularly relates to low-smoke fireproof heat-resistant aluminum foil reinforced polyolefin foam, a preparation method and application. 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 foamed by 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 phosphorus elements, nitrogen elements and bromine elements, wherein the sum of the phosphorus elements and the nitrogen elements accounts for 60wt%-80wt% of the total mass of all flame-retardant elements, the bromine elements account for 15wt%-30wt% of the total mass of all flame-retardant elements, and the mass ratio of the phosphorus elements to the nitrogen elements is less than or equal to 3:1. By adjusting the proportions of the bromine elements, the phosphorus elements and the nitrogen elements in the flame retardant, the flame-retardant elements can play a synergistic flame-retardant role, and the aluminum foil reinforced polyolefin foam with low smoke, fireproof and heat-resistant properties is obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polymer materials, more particularly, relates to a low-smoke fireproof heat-resistant aluminum foil reinforced polyolefin foam, a preparation method and application. BACKGROUND

[0002] Polyolefin foam is widely used in rail transit due to its light weight, excellent thermal insulation performance, electrical insulation and good chemical stability. However, when the conventional polyolefin foam is exposed to fire, it will produce a large amount of smoke, and the heat spreads quickly, making the flame easily penetrate the polyolefin foam. The poor temperature resistance and combustion characteristics limit the application of polyolefin foam in rail transit.

[0003] The polyolefin foam and the aluminum foil are compounded, which can effectively improve the temperature resistance and combustion characteristics of the polyolefin foam. The conventional aluminum foil compounded polyolefin foam is bonded together by double-sided adhesive. When exposed to fire, the middle adhesive layer is easy to decompose, causing the aluminum foil and the polyolefin foam to separate, and the polyolefin foam is exposed to the open flame scene, which cannot effectively play a protective role. At the same time, the combustion of the adhesive layer will produce a large amount of smoke and release toxic gases, causing great harm. SUMMARY

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a low-smoke fireproof heat-resistant aluminum foil reinforced polyolefin foam, a preparation method and application, which aims to solve the problems of poor bonding performance between aluminum foil and polyolefin foam, easy separation, and large amount of toxic gas generated when the existing aluminum foil compounded polyolefin foam is burned at high temperature, and does not meet the requirements of low smoke, fireproof and heat-resistant.

[0005] To achieve the above-mentioned purpose, the present application provides a low-smoke fireproof 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 from a polyolefin resin, a flame retardant, a foaming agent, an adhesive and an auxiliary agent; the aluminum foil structure comprises an aluminum foil layer;

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

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

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

[0009] Preferably, the mass ratio of the polyolefin-based resin, the flame retardant, the foaming agent, the adhesive, and the 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 comprises a functional coating and / or a reinforcing rib.

[0012] Preferably, the cell diameter of the polyolefin foam is 100-600 μm, the density is 25-200 kg / m 3 , and the ratio of the cell diameter to the 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 heat radiation value of the aluminum-foil-reinforced polyolefin foam is 50 kW / m 2 , the maximum average heat release rate is less than 20 kW / m 2 , the VOF4 is less than 200, the maximum specific optical density value within 10 min is less than 150, and the average value of the toxicity index is less than 1.

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

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

[0017] Preferably, the median particle diameter of the flame retardant is 1-100 μm, and further preferably 7-40 μm.

[0018] Preferably, the foaming agent has a gas generation amount of 220-300 mL / g and a median particle diameter of 1-50 μm. Further preferably, the foaming agent has a gas generation amount of 220-240 mL / g and a median particle diameter of 14-20 μm.

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

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

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

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

[0023] In another aspect, the application also provides a preparation method of the above-mentioned aluminum foil reinforced polyolefin foam, comprising the following steps:

[0024] S1, according to the proportion, the above-mentioned polyolefin resin, adhesive, foaming agent, flame retardant and auxiliary agent are mixed and blended, and then granulated to obtain full formula particles, and then the full formula particles are extruded to obtain a substrate;

[0025] S2, the above-mentioned substrate is irradiated and crosslinked to obtain a mother sheet, and then the above-mentioned mother sheet is foamed to obtain a foamed sheet;

[0026] S3, the above-mentioned aluminum foil structure is placed on the above-mentioned foamed sheet, and then a hot compounding process is carried out to obtain an aluminum foil reinforced polyolefin foam.

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

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

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

[0030] Preferably, the specific operation of the hot air compounding is that the above-mentioned aluminum foil structure is placed on the above-mentioned foamed sheet, and then hot air at 200°C to 250°C is introduced for compounding.

[0031] Preferably, the specific operation of the hot pressing compounding is that the above-mentioned aluminum foil structure is placed on the above-mentioned foamed sheet, and then compounding is carried out by a pair of rollers at 150°C to 250°C.

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

[0033] Overall, compared with the prior art, the above technical solutions conceived by the application mainly have the following technical advantages:

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

[0035] (2) The application adjusts the mass fraction of the flame retardant and the adhesive, the types and proportions of the flame-retardant elements, etc., so as to achieve the synergistic flame-retardant effect of the flame-retardant elements, reduce the smoke emission during combustion, improve the overall uniformity of the flame retardant, and improve the low-smoke, fireproof and heat-resistant properties of the foam. In addition, by adjusting the mass fraction of the polyolefin resin and the foaming agent in the polyolefin foam, the pore size, density, ratio of the pore size and density of the foam are adjusted, the contact area of the polyolefin foam and the aluminum foil structure is increased, the adhesion of the foam and the aluminum foil structure is improved, and the aluminum foil reinforced polyolefin foam with good adhesion, low smoke, fireproof and heat-resistant properties is prepared by process adjustment. In addition, the preparation method provided by the application is simple, has low processing difficulty, and can be mass-produced. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0038] In order to make the purpose, technical scheme and advantages of the application more clear, the application will be further described in detail below with reference to the examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application.

[0039] The application provides a low-smoke fireproof 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 polyolefin resin, a flame retardant, a foaming agent, an adhesive and an auxiliary agent; and the aluminum foil structure comprises an aluminum foil layer;

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

[0041] The application can synergistically control the smoke density and the flame-retardant effect of the foam during combustion by adjusting the proportions of the bromine element, the phosphorus element and the nitrogen element in the flame retardant. The amount of the bromine element in the flame retardant is relatively small, which can reduce the smoke density, the release of corrosive and toxic gases during the combustion of the overall material. In addition, the generated hydrogen bromide gas can isolate the foam material from oxygen, thereby improving the flame-retardant efficiency. The flame retardant containing the phosphorus element or the nitrogen element has a high melting point, which can absorb heat by melting to isolate the fire source and reduce the speed of flame spread. At the same time, the phosphorus element and the nitrogen element can react with oxygen to generate phosphoric acid, dipotassium hydrogen phosphate, nitrogen and nitric oxide, thereby reducing the flame temperature and the heat radiation intensity and slowing down the chemical reaction rate. In addition, the phosphorus element can also generate poly-metaphosphoric acid to form a protective film on the surface of the combustion body, isolate the material from air and reduce the degree of afterglow. The generated poly-metaphosphoric acid is a strong acid with strong dehydrating property, which can cause the polymer to dehydrate and carbonize to form a carbonized layer on the surface, thereby isolating the polymer inside from air and preventing combustion. In summary, the application can achieve excellent flame-retardant effect with a low amount of flame retardant, which can significantly reduce the difficulty of making the foam and the production cost compared with the existing foam.

[0042] In some embodiments, the mass ratio of the phosphorus element to the nitrogen element in the flame retardant is (1-3):1. The bromine element and the nitrogen element in the flame retardant can reduce the concentration of oxygen and flammable gas by the gas-phase flame-retardant mechanism, and reduce the necessary conditions for combustion. At the same time, the phosphorus element can accelerate the carbonization of the polymer by the condensed-phase flame-retardant mechanism to form a carbonized layer, which protects the polymer below the carbonized layer from the fire source. By controlling the proportion of the flame-retardant elements and the ratio of the phosphorus element to the nitrogen element, the bromine element, the phosphorus element and the nitrogen element can play a synergistic flame-retardant effect to improve the low-smoke, flame-retardant and heat-resistant properties of the foam. When the ratio of the phosphorus element to the nitrogen element in the flame retardant is too large, such as 4:1, the synergistic flame-retardant effect between the flame-retardant components is poor, which ultimately leads to poor low-smoke, flame-retardant and heat-resistant properties of the foam.

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

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

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

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

[0047] In some embodiments, the aluminum foil structure further comprises 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, i.e., the structure of the aluminum foil reinforced polyolefin foam is polyolefin foam, aluminum foil layer, and 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, i.e., the structure of the aluminum foil reinforced polyolefin foam is polyolefin foam, reinforcing rib, and aluminum foil layer arranged in sequence. It can be understood that the type and thickness of the functional coating and the reinforcing rib are not limited in the present application, and can be selected by those skilled in the art 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 reinforcing layer.

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

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

[0050] In some embodiments, after the aluminum foil reinforced polyolefin foam is subjected to a 600°C flame for 3 min, the polyolefin foam and the aluminum foil structure do not separate.

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

[0052] In preferred embodiments, the flame retardant described above 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 elements, magnesium elements, and antimony elements.

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

[0054] The present application does not have special limitations on the types of foaming agents described above, and preferably foaming agents with low cost and good foaming effect, such as but not limited to one or more of azodicarbonamide, OBSH foaming agent, N,N'-dinitrosopentamethylenetetramine, 4,4-oxobisbenzenesulfonylhydrazide, inorganic carbonate, and bicarbonate. In some embodiments, the foaming agent described above has a gas generation amount of 220 to 300 mL / g and a median particle size of 1 to 50 microns, preferably a gas generation amount of 220 to 240 mL / g and a median particle size of 14 to 20 microns.

[0055] In some embodiments, the ratio of the median particle size of the flame retardant described above to the median particle size of the foaming agent is (0.5 to 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 uniformly dispersed, and in the foaming stage, the flame retardant can play a role in heterogeneous nucleation, serving as a starting site for foaming cells, generating uniform foaming cells, and not exhibiting anisotropy during combustion, which is conducive to improving the overall uniformity of flame retardation and improving the flame retardation effect.

[0056] In some embodiments, the adhesive described above 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 ethylene-acrylic acid copolymer described above is 9% to 20%. In some embodiments, the mass percentage of methyl acrylate in the ethylene-methyl acrylate copolymer described above is 9% to 30%.

[0058] To meet the requirements of different application environments, the aluminum foil reinforced polyolefin foam prepared by the present application further comprises 1 to 5 parts by mass of an auxiliary agent to impart various properties to the foam. The auxiliary agent described above includes but is not limited to one or more of antioxidants, dispersants, and sensitizers. It can be understood that the present application does not limit the specific types of antioxidants, dispersants, and sensitizers described above, and those skilled in the art can select appropriate auxiliary agents according to actual needs.

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

[0060] S1, the polyolefin resin, the adhesive, the foaming agent and the additive are mixed and blended by internal mixing, and granulation is performed to obtain full-formulation particles, and then the full-formulation particles are extruded to obtain a substrate;

[0061] S2, the substrate is irradiated and crosslinked to obtain a mother sheet, and then the mother sheet is foamed to obtain a foamed sheet;

[0062] S3, the aluminum foil structure is placed on the foamed sheet, and a thermal compounding process is performed to obtain the aluminum foil reinforced polyolefin foam.

[0063] In order to improve the dispersion uniformity of each raw material, in some embodiments, the step S1 is as follows: the total foaming agent is mixed and blended by internal mixing with part of the mass fraction of the polyolefin resin, the adhesive and the additive to obtain a foaming agent master batch; the total flame retardant is mixed and blended by internal mixing with the remaining mass fraction of the polyolefin resin, the adhesive and the additive to obtain a flame retardant master batch; then the foaming agent master batch and the flame retardant master batch are stirred and uniformly mixed, and then granulation is performed to obtain full-formulation particles, and then the full-formulation particles are extruded to obtain a substrate.

[0064] It can be understood that the application does not limit the process of the internal mixing and blending in step S1, as long as each material can be uniformly dispersed.

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

[0066] In some embodiments, in step S2, the foaming temperature is 180-300 DEG C.

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

[0068] In some embodiments, the specific operation of the hot air compounding is that the aluminum foil structure is placed on the foamed sheet, and then hot air at 200-250 DEG C. is introduced for compounding.

[0069] In some embodiments, the specific operation of the hot pressing compounding is that the aluminum foil structure is placed on the foamed sheet, and then compounding is performed by a pair of rollers at 150-250 DEG C.

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

[0071] It should be understood that materials identical or similar in type, model, quality, property or function to the reagents and instruments used in the following examples can be used to carry out the present application. The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents and the like used in the following examples can be obtained commercially unless otherwise specified.

[0072] The following are examples and comparative examples:

[0073] Example 1

[0074] The components and mass fractions of the aluminum foil reinforced polyolefin foam of the present example are shown in Table 1.

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

[0076]

[0077] The preparation steps of the aluminum foil reinforced polyolefin foam provided by the present example are as follows:

[0078] (1) Foaming agent master batch: the polyolefin resin, adhesive, auxiliary agent and all foaming agents with a mass fraction of 50% each are put into a mixing mill for mixing and milling, the temperature of the milling bin is 115°C, the milling time is 15 min, then the mixture is discharged into a granulator for granulation to obtain a foaming agent master batch.

[0079] (2) Flame retardant master batch: the remaining polyolefin resin, adhesive, auxiliary agent and all flame retardants are put into a mixing mill for mixing and milling, the temperature of the milling bin is 150°C, the milling time is 20 min, then the mixture is discharged into a granulator for granulation to obtain a flame retardant master batch.

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

[0081] (4) Foamed sheet: the above base sheet is subjected to electron irradiation crosslinking, the electron energy for irradiation crosslinking is 2.0 MeV, the irradiation dose is 25 Mrad, and the crosslinking degree of the base sheet is controlled at 55% to obtain a mother sheet; the above mother sheet is subjected to free foaming at a foaming temperature of 230°C to obtain a 5 mm foamed sheet.

[0082] (5) An aluminum foil structure is covered on the foamed sheet of step (4) and is subjected to hot press compounding at a temperature of 180°C to obtain an aluminum foil reinforced polyolefin foam P1.

[0083] Example 2

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

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

[0086]

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

[0088] The preparation of the foaming agent master batch, the flame retardant master batch and the base sheet is the same as in Example 1. The above base sheet 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 base sheet is controlled to be 60%, to obtain a master sheet; the above master sheet is subjected to free foaming, the foaming temperature is 200°C, to obtain a 3mm foamed sheet. An aluminum foil structure is covered on the above foamed sheet, hot air compounding is carried out by passing in 230°C hot air, to obtain the aluminum foil reinforced polyolefin foam P2.

[0089] Example 3

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

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

[0092]

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

[0094] The preparation of the foaming agent master batch, the flame retardant master batch and the base sheet is the same as in Example 1. The above base sheet 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 base sheet is controlled to be 50%, to obtain a master sheet; the above master sheet is subjected to free foaming, the foaming temperature is 220°C, to obtain a 10mm foamed sheet. An aluminum foil structure is covered on the above foamed sheet, hot pressing compounding is carried out by passing through a roller with a temperature of 180°C, to obtain the aluminum foil reinforced polyolefin foam P3.

[0095] Example 4

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

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

[0098]

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

[0100] The foaming agent master batch, the flame retardant master batch and the substrate were prepared according to the method of Example 1. The substrate was subjected to electron irradiation crosslinking, the electron energy of the irradiation crosslinking was 4.0 MeV, the irradiation dose was 20 Mrad, and the crosslinking degree of the substrate was controlled to be 57%, to obtain a master sheet. The master sheet was subjected to free foaming, the foaming temperature was 200°C, to obtain a 7mm foamed sheet. An aluminum foil structure was covered on the foamed sheet, and hot-pressing was performed on the aluminum foil structure and the foamed sheet by a roller with a temperature of 170°C, to obtain an aluminum foil reinforced polyolefin foam P4.

[0101] Example 5

[0102] The components and mass fractions of the aluminum foil reinforced polyolefin foam provided in the example were shown in Table 5.

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

[0104]

[0105]

[0106] The preparation steps of the aluminum foil reinforced polyolefin foam provided in the example were as follows:

[0107] The foaming agent master batch, the flame retardant master batch and the substrate were prepared according to the method of Example 1. The substrate was subjected to electron irradiation crosslinking, the electron energy of the irradiation crosslinking was 2.0 MeV, the irradiation dose was 15 Mrad, and the crosslinking degree of the substrate was controlled to be 48%, to obtain a master sheet. The master sheet was subjected to free foaming, the foaming temperature was 190°C, to obtain a 4mm foamed sheet. An aluminum foil structure was covered on the foamed sheet, and hot-pressing was performed on the aluminum foil structure and the foamed sheet by blowing hot air with a temperature of 200°C, to obtain an aluminum foil reinforced polyolefin foam P5.

[0108] Example 6

[0109] The components and mass fractions of the aluminum foil reinforced polyolefin foam provided in the example were shown in Table 6.

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

[0111]

[0112]

[0113] The preparation steps of the aluminum foil reinforced polyolefin foam provided in the example were as follows:

[0114] The preparation of the foaming agent masterbatch, flame retardant masterbatch, and substrate was the same as in Example 1. The substrate was cross-linked by electron irradiation at an electron energy of 3.0 MeV and an irradiation dose of 15 Mrad, with a cross-linking degree of 55% to obtain a master sheet. The master sheet was then free-form foamed at a temperature of 220°C to obtain a 3 mm foamed sheet. An aluminum foil structure was placed over the foamed sheet and hot-pressed with rollers at 200°C to obtain aluminum foil-reinforced polyolefin foam P6.

[0115] Example 7

[0116] The components and mass 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 the foaming agent masterbatch, flame retardant masterbatch, and substrate was the same as in Example 1. The substrate was cross-linked by electron irradiation at an electron energy of 2.0 MeV and an irradiation dose of 10 Mrad, with a cross-linking degree of 47%, to obtain a master sheet. The master sheet was then free-form foamed at a temperature of 190°C to obtain a 3 mm foamed sheet. An aluminum foil structure was placed over the foamed sheet and hot-pressed with rollers at 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 the foaming agent masterbatch, flame retardant masterbatch, base sheet, and mother sheet was the same as in Example 1. The mother sheet was subjected to free-style foaming at a foaming temperature of 210°C to produce a 5 mm foam sheet. An aluminum foil structure was placed over the foam sheet and hot-pressed with rollers at 180°C to produce aluminum foil-reinforced polyolefin foam P8.

[0127] Comparative Example 1

[0128] The components and mass parts of the polyolefin foam of the present comparative example are shown in Table 9.

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

[0130]

[0131]

[0132] The polyolefin foam of the present comparative example is prepared by the same method as Example 1, wherein the crosslinking degree of the substrate is 52%, and a 5mm foamed sheet, i.e. polyolefin foam D1, is prepared.

[0133] Comparative Example 2

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

[0135] Comparative Example 3

[0136] The polyolefin foam of the present comparative example does not include an aluminum foil structure, and other parameters are the same as those of Example 2, and then a foamed sheet, i.e. 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 the present comparative example is 3 parts of ethylene-acrylic acid copolymer and 1 part of aluminic acid ester 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 by the present comparative example is as follows:

[0140] The preparation of the foaming agent master batch, the flame retardant master batch, the substrate, the master sheet and the foamed sheet is the same as that of Example 2. The aluminum foil structure is bonded to the above-mentioned foamed sheet using an adhesive, and then hot air lamination is performed according to the method of Example 2 to obtain the aluminum foil reinforced polyolefin foam D4.

[0141] Comparative Example 5

[0142] The components and mass parts of the aluminum foil reinforced polyolefin foam of the present comparative example are shown in Table 10.

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

[0144]

[0145]

[0146] The aluminum foil reinforced polyolefin foam D5 of the present comparative example was produced in the same manner as Example 2.

[0147] The properties of the products produced in Examples 1 to 8 and Comparative Examples 1 to 5 were tested by the following methods.

[0148] (1) Cell diameter of the foam: Five 100 mm x 50 mm (length x width) samples were cut from the foam sheet, placed in liquid nitrogen for 30 minutes, and then removed. The samples were fractured in the middle to obtain 10 samples with fractured surfaces. An electron microscope was used to take 200x magnification photographs of the fractured surfaces of each sample. Two locations were selected on each fractured surface, and the diameter of all the cells in each location was measured. The arithmetic mean of the diameters was taken as the cell diameter.

[0149] (2) Density of the foam: The density was tested in accordance with the standard JIS K6767 (1999) "Foamed Plastics - Polyethylene - Test Method".

[0150] (3) Critical heat radiation value (CFE): The CFE was tested in accordance with the standard ISO 5660-1.

[0151] (4) Maximum average heat release rate (HRR): The HRR was tested in accordance with the standard ISO 5660-1 (heat radiation level set to 50 kW / m 2 ).

[0152] (5) Optical density cumulative value (VOF4) for 4 minutes before the test, maximum specific optical density value (Ds max ) within 10 minutes, and toxicity index CITG average value: The values were tested in accordance with the standard ISO 5659-2.

[0153] (6) Adhesion test: The product was cut into 15 cm x 15 cm sheets, and the aluminum foil surface was burned using an ethane flame at 600°C for 3 minutes. After the flame was removed and the product cooled, the foam was peeled away from the aluminum foil. The aluminum foil surface was observed to determine whether the foam was adhered to the aluminum foil. If the foam was adhered to the aluminum foil, the foam and the aluminum foil did not separate, and the adhesion was good. If the foam was not adhered to the aluminum foil, the foam and the aluminum foil separated, and the adhesion was poor.

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

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

[0156]

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

[0158]

[0159] The experimental results show that, from the aspects of formula preparation and process improvement, by adjusting the ratio of cell and density, the amount of adhesive, the proportion of bromine element, phosphorus element and nitrogen element, the ratio of phosphorus element and nitrogen element, the particle size of foaming agent and flame retardant, the flame retardant performance of the foam, the bonding performance of the foam and the aluminum foil structure are synergistically controlled, the synergistic flame retardant effect is played, the smoke emission during combustion is reduced, at the same time, the uniformity of the flame retardant of the whole foam can be effectively improved. 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 effectively support the foam structure, slow down the combustion speed of the foam, and further reduce the smoke concentration released to the outside. The critical heat radiation value (CFE) of the aluminum foil reinforced polyolefin foam prepared by the present application is 50kW / m 2 , the maximum average heat release rate (HRR) is less than 20kW / m 2 , the optical density cumulative value (VOF4) in the first 4min of the test is less than 200, the maximum specific optical density value (Ds max ) within 10min is less than 150, the average value of the toxicity index CITG is less than 1, the foam and the aluminum foil structure do not separate during high temperature combustion at 600℃, the bonding performance is good, and can be applied to railway carriages and other rail transit scenes.

[0160] The foam of Comparative Example 1 does not contain aluminum foil structure, and the flame retardant in the foam formula does not contain phosphorus element and nitrogen element. When the prepared foam is tested for critical heat radiation value (CFE), the foam completely decomposes, and no phenomenon of flame stopping propagation and extinguishing occurs, indicating that the foam has poor flame retardant performance. Comparative Example 2 increases the aluminum foil structure by a thermal compounding process based on Comparative Example 1, but the combustion characteristics of the foam are still poor, which does not meet the requirements of low smoke fire resistance and heat resistance, and is not suitable for rail transit scenes. The foam of Example 1 synergistically improves the temperature resistance and combustion characteristics of the foam by adjusting the formula and structure of the foam, and the bonding performance of the foam and the aluminum foil structure.

[0161] Example 2 synergistically adjusts the formula and process improvement of the foam, so that the foam and the aluminum foil structure do not separate during high temperature combustion (as shown in Figure 1 ), and have excellent low smoke fire resistance and heat resistance. The foam prepared in Comparative Example 3 does not contain aluminum foil structure compared with Example 2, and the low smoke fire resistance and heat resistance of the prepared foam are poor. Comparative Example 4 reduces the amount of adhesive based on Comparative Example 3, and uses adhesive and thermal compounding process to compound the aluminum foil structure, and the low smoke fire resistance and heat resistance of the prepared foam are slightly better than those of Comparative Example 3, but still do not meet the application scene requirements, and the foam and the aluminum foil structure separate during high temperature combustion (as shown in Figure 2 ), and the bonding performance is poor.

[0162] The foam prepared by Comparative Example 5 separates from the aluminum foil structure when burning at high temperature, and the reason is that the ratio of the pore size and the density is too large, the contact area between the foam and the aluminum foil structure is reduced, thereby reducing the bonding performance, and the ratio of the phosphorus element and the nitrogen element in the flame retardant is too large, the synergistic flame retardance between the flame retardant components is poor, and finally the low smoke fireproof heat resistance of the foam is poor.

[0163] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Low smoke, fireproof and heat-resistant aluminum foil reinforced polyolefin foam, characterized by: It includes polyolefin foam and an aluminum foil structure arranged on the surface of the polyolefin foam; the polyolefin foam is foamed from polyolefin resin, flame retardant, foaming agent, adhesive and additive; 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; 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).

2. 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.

3. The aluminum foil reinforced polyolefin foam according to claim 1 or 2, characterized in that: The polyolefin foam has a pore size of 100-600 μm and a density of 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 , the cumulative optical density value VOF4 in the first 4 minutes of the test 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; After the aluminum foil surface of the aluminum foil reinforced polyolefin foam is burned using a 600° C. flame for 3 minutes, the polyolefin foam and the aluminum foil structure are not separated.

4. 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.

5. 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 generation capacity of 220-300 mL / g and a median particle size of 1-50 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.

6. The aluminum foil reinforced polyolefin foam according to claim 5, characterized in that: The flame retardant further comprises other elements, wherein the other elements account for 0 wt% to 20 wt% 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 generation capacity of 220-240 mL / g and a median particle size of 14-20 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%.

7. A method for preparing the aluminum foil reinforced polyolefin foam according to any one of claims 1 to 6, characterized in that: The steps include: S1. Kneading and blending the polyolefin resin, adhesive, foaming agent, flame retardant and additives according to a ratio, and granulating to obtain fully formulated particles, and then extruding the fully formulated particles to obtain a substrate; S2, irradiating and cross-linking the substrate to obtain a mother sheet, and then foaming the mother sheet to obtain a foamed sheet; S3. Placing the aluminum foil structure on the foam sheet and subjecting it to a thermal composite process to obtain aluminum foil reinforced polyolefin foam.

8. The preparation method according to claim 7, 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 as follows: 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 with a roller at 150° C. to 250° C.

9. A fireproof material for rail transportation, characterized in that: The invention comprises the aluminum foil reinforced polyolefin foam according to any one of claims 1 to 6.

Images