Lightweight waterproof roll and preparation method thereof

Abstract

The present invention relates to a lightweight waterproof roll and a preparation method thereof, comprising a first resin layer and a second resin layer, wherein heat-expandable microspheres are added to the first or second resin layer, the heat-expandable microspheres comprising a core material and an outer shell, the core material comprising a hydrocarbon compound and a liquid phosphorus-containing flame retardant, and the outer shell being an acrylic ester polymer obtained by polymerizing monomers; the polymerized monomers comprising a first polymerized monomer and a second polymerized monomer, the first polymerized monomer being an acrylic phosphate monomer, and the second polymerized monomer being at least one of a nitrile monomer, a carboxyl acrylic monomer, and a methacrylate monomer. The present invention provides a lightweight waterproof roll with a multi-layered resin layer structure, adding specific heat-expandable microspheres to one of the layers, and utilizing a multiple flame-retardant approach: the phosphorus-containing polymer outer shell of the heat-expandable microspheres and the phosphorus-containing flame retardant coating within the heat-expandable microspheres. This allows the waterproof roll to maintain its original flame retardancy while reducing its weight while maintaining mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of building waterproof materials, and particularly relates to a lightweight waterproof coiled material and a preparation method thereof. Background Art

[0002] Polyvinyl chloride (PVC) waterproofing membrane is a high-performance polymer waterproofing material, primarily made from polyvinyl chloride resin and fillers, along with various additives. It boasts high tensile strength, high elongation, minimal dimensional change, excellent low-temperature flexibility, strong resistance to root penetration, and a long service life. It also boasts reliable and robust welding and is environmentally friendly and pollution-free. However, the heavy weight of traditional PVC waterproofing membranes can make installation and transportation difficult.

[0003] In the prior art, there are also some means to reduce the weight of PVC waterproof membranes. For example, when preparing waterproof membranes, a certain amount of foaming agent is added. Although this can reduce the weight of the waterproof membranes, it also damages the mechanical properties of the waterproof membranes and the flame retardant properties of the membranes are not improved. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide an improved lightweight waterproof roll material, which has the advantages of light weight while maintaining mechanical properties and improving the flame retardancy of the waterproof roll material.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A lightweight waterproof roll material, comprising a first resin layer and a second resin layer stacked in sequence, wherein heat-expandable microspheres are added to the first resin layer or the second resin layer, the heat-expandable microspheres comprising a core material and a shell covering the core material, the core material comprising a hydrocarbon and a liquid phosphorus-containing flame retardant, and the shell being an acrylic polymer obtained by polymerizing a monomer;

[0007] The polymerizable monomers include a first polymerizable monomer and a second polymerizable monomer, wherein the first polymerizable monomer is an acrylic acid phosphate monomer, and the second polymerizable monomer is at least one of a nitrile monomer, a carboxyl acrylic acid monomer, and a methacrylic acid ester monomer.

[0008] According to some embodiments of the present invention, the first resin layer and the second resin layer are PVC resin layers, the heat-expandable microspheres are added to the second resin layer, and the amount of the heat-expandable microspheres is 0.5-1% of the total amount of raw materials of the second resin layer.

[0009] In some specific embodiments, the thickness ratio of the first resin layer to the second resin layer is 5:1-15.

[0010] In some specific embodiments, the particle size of the heat-expandable microspheres is 10 to 80 μm. The particle size of the heat-expandable microspheres should be within a certain range. If the particle size is too large, it is difficult to meet the requirements of reducing the density of the waterproof membrane and maintaining the mechanical properties.

[0011] According to some implementation aspects of the present invention, the raw materials of the first resin layer include PVC resin, plasticizer and filler;

[0012] The raw materials of the second resin layer include PVC resin, heat-expandable microspheres, plasticizer and filler;

[0013] In the first resin layer and the second resin layer, the mass ratio of the PVC resin, the plasticizer and the filler is 1:0.2 to 1:0.1 to 0.4;

[0014] In the second resin layer, the amount of the heat-expandable microspheres is 0.5-1% of the total amount of raw materials of the second resin layer.

[0015] In some specific embodiments, the raw material formulas of the first resin layer and the second resin layer independently include:

[0016] 80-100 parts of PVC resin;

[0017] 20-80 parts of plasticizer;

[0018] 15-30 parts of filler;

[0019] The second resin layer also includes heat-expandable microspheres in an amount of 0.5 to 1% of the total raw material amount of the second resin layer.

[0020] In some specific embodiments, the raw material formula of the first resin layer and the second resin layer further includes 2 to 6 parts of auxiliary agents, and the auxiliary agents are one or a combination of heat stabilizers and anti-ultraviolet agents.

[0021] Furthermore, the auxiliary agent is 2 to 5 parts of a heat stabilizer and 0.01 to 0.2 parts of an anti-ultraviolet agent.

[0022] The anti-ultraviolet agent is a combination of one or more of an ultraviolet absorber, a light shielding agent, and a hindered amine light stabilizer.

[0023] In some specific embodiments, the plasticizer is one or a combination of DOP, DINP, DOTP, and epoxidized soybean oil.

[0024] In some specific embodiments, the filler is a combination of one or more of titanium dioxide, calcium carbonate, talc, and clay.

[0025] In some specific embodiments, the mass ratio of the first polymerizable monomer, the second polymerizable monomer, the hydrocarbon compound, and the liquid phosphorus-containing flame retardant is 30-50:50-100:30-50:5-30.

[0026] In some specific embodiments, the acrylic acid phosphate monomer is one or a combination of acrylic acid monophosphate, acrylic acid diphosphate, methacrylic acid monophosphate, methacrylic acid diphosphate, pentabromobenzyl acrylate, methacryloyloxyethyl phosphate, and 2-hydroxyethyl methacrylate phosphate.

[0027] In some specific embodiments, the nitrile monomer is one or a combination of acrylonitrile, methacrylonitrile, chloroacrylonitrile, and ethoxyacrylonitrile.

[0028] In some specific embodiments, the carboxyl acrylic monomer is one or a combination of acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, monoethyl maleate, and monobutyl maleate.

[0029] In some specific embodiments, the methacrylate monomer is one or a combination of methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, and benzyl methacrylate.

[0030] In some specific embodiments, the hydrocarbon is a hydrocarbon with a boiling point above 60°C.

[0031] In some specific embodiments, the liquid phosphorus-containing flame retardant is one or a combination of tributyl phosphate, dimethyl methyl phosphate, diethyl ethyl phosphate, tricresyl phosphate, diphenyl methyl phosphate, tri(xylene) phosphate, tri(butoxyethyl) phosphate, bisphenol A-bis(diphenyl phosphate) and resorcinol bis(diphenyl phosphate).

[0032] In some specific embodiments, the mass ratio of the nitrile monomer, the carboxyl acrylic monomer, and the methacrylate monomer is 50-100:5-15:20-50.

[0033] According to some implementation aspects of the present invention, the heat-expandable microspheres further include a water-dispersible halogen-free flame retardant dispersed in the core material and / or the shell.

[0034] In some specific embodiments, the water-dispersible halogen-free flame retardant is one or a combination of magnesium hydroxide, hydrated magnesium hydroxide, aluminum hydroxide, hydrated aluminum hydroxide, zinc oxide, and magnesium oxide; and / or the mass ratio of the water-dispersible halogen-free flame retardant to the liquid phosphorus-containing flame retardant is 5-20:5-30.

[0035] In some specific embodiments, the raw material formula of the heat-expandable microspheres comprises, by weight:

[0036] 30-50 parts of hydrocarbons;

[0037] 30 to 50 parts of the first polymerizable monomer;

[0038] 50-100 parts of the second polymerizable monomer;

[0039] 5-20 parts of water-dispersible halogen-free flame retardant;

[0040] 5 to 30 parts of liquid phosphorus-containing flame retardant.

[0041] According to some embodiments of the present invention, the heat-expandable microspheres are further subjected to surface modification treatment, which includes dispersing unmodified heat-expandable microspheres into a dispersion containing an organic carbon-forming agent, a nanocarbon material, and a coupling agent to obtain surface-modified heat-expandable microspheres.

[0042] In some specific embodiments, the mass ratio of the organic carbon-forming agent to the inorganic carbon material is 1:0.5 to 1.5.

[0043] In some specific embodiments, the organic carbon-forming agent is one or a combination of an organic phosphorus carbon-forming agent, a thermoplastic phenolic resin carbon-forming agent, a polyamide carbon-forming agent, a triazine derivative carbon-forming agent, and a hyperbranched macromolecular flame-retardant carbon-forming agent.

[0044] In some specific embodiments, the nano-carbon material is one or a combination of carbon nanotubes and graphene.

[0045] In some specific embodiments, the coupling agent is a silane coupling agent, such as one or a combination of γ-aminopropyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane.

[0046] In some specific embodiments, the mass ratio of the unmodified heat-expandable microspheres to the organic carbon-forming agent is 10-50:1-5; the mass ratio of the unmodified heat-expandable microspheres to the coupling agent is 100:0.1-5.

[0047] In some specific embodiments, the method for preparing the surface-modified heat-expandable microspheres comprises the following steps:

[0048] (1) uniformly mixing water, a water-dispersible halogen-free flame retardant, an electrolyte, and an emulsifier to obtain an aqueous dispersion;

[0049] (2) uniformly mixing the first polymerizable monomer, the second polymerizable monomer, the initiator, the hydrocarbon compound, and the liquid phosphorus-containing flame retardant to obtain an oil phase dispersion;

[0050] (3) adding the oil phase dispersion to the aqueous phase dispersion under stirring to obtain a presuspension, and then polymerizing under inert gas conditions to obtain surface-unmodified thermally expandable microspheres;

[0051] (4) dispersing the surface-unmodified heat-expandable microspheres in a dispersion containing an organic carbon-forming agent, a nanocarbon material, and a coupling agent to obtain the surface-modified heat-expandable microspheres.

[0052] In some specific embodiments, in step (1), the amount of water is 300-500 parts, the amount of electrolyte is 50-100 parts, and the amount of emulsifier is 0.3-3 parts; in step (2), the amount of initiator is 1-5 parts.

[0053] In some specific embodiments, in step (3), the polymerization reaction is carried out at a pressure of 1.5 to 1.8 MPa and a temperature of 65 to 80° C., and the polymerization reaction time is 12 to 24 hours.

[0054] In some specific embodiments, in step (4), the dispersion medium used in the dispersion liquid is one or a combination of methanol and ethanol.

[0055] In some specific embodiments, in step (4), the surface-unmodified heat-expandable microspheres are added to the dispersion, mixed evenly, and then kept at 60±10° C. for 24 to 30 hours, washed, and filtered to obtain the surface-modified heat-expandable microspheres.

[0056] The second technical solution adopted by the present invention is a method for preparing the waterproof roll material described above, comprising melting the raw materials of the first resin layer and the raw materials of the second resin layer separately, and co-extruding them to obtain the waterproof roll material.

[0057] In some specific embodiments, the extrusion temperature is 160-180° C., and the screw speed is 120-140 rpm.

[0058] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0059] The present invention arranges the waterproof roll into a multi-layer resin layer structure, adds specific heat-expandable microspheres in one of the layers, and utilizes multiple flame retardant measures of the phosphorus-containing polymer shell of the heat-expandable microspheres and the phosphorus-containing flame retardant coated inside, so that the waterproof roll not only maintains its original flame retardancy, but also reduces the weight of the waterproof roll while maintaining its mechanical properties.

[0060] Compared with traditional waterproof membranes, the lightweight waterproof membrane of the present invention has special properties such as lightness and softness, high elasticity and impact resistance, and flame retardancy, and maintains good mechanical properties, and has significant advantages such as low transportation cost and convenient construction. DETAILED DESCRIPTION

[0061] As described in the background art, the existing PCV waterproof membrane is difficult to resolve the contradiction between its own weight and mechanical properties, and the flame retardancy of the membrane has not been improved.

[0062] Heat-expandable microspheres are hollow thermoplastic polymer microspheres. Conventional heat-expandable microspheres typically consist of a thermoplastic polymer shell and an alkane gas interior. When the microspheres are heated, the gas pressure within the shell increases and the shell softens, causing the microspheres to expand in volume. Upon cooling, the shell hardens, and the expanded volume stabilizes, resulting in significant changes in the microsphere's diameter and volume. After full expansion, the microsphere's volume can increase dozens of times. However, the presence of the alkane gas and organic polymer shell within conventional heat-expandable microspheres makes them flammable.

[0063] The main idea of ​​the present invention is to redesign a flame-retardant heat-expandable microsphere. By adopting multiple flame-retardant measures of a phosphorus-containing polymer shell and an internal coating of a halogen-free phosphorus-containing flame retardant, combined with setting the waterproof membrane into a multi-layer structure and introducing the heat-expandable microspheres into one of the layers, on the one hand, the high foaming ratio of the heat-expandable microspheres is utilized to effectively reduce the density of the membrane, thereby achieving the effect of reducing weight and cost. On the other hand, the heat-expandable microspheres are added to one of the layers, and the influence of their foaming structure on the mechanical properties of the membrane is reduced, which will not cause a significant decline in the overall mechanical properties of the waterproof membrane. On the other hand, the heat-expandable microspheres have multiple flame-retardant effects, which compensate for the decline in flame retardant performance of the waterproof membrane due to the formation of internal pores.

[0064] A further concept of the present invention is to use a combination of inorganic carbon materials and organic carbon-forming agents to modify the surface of the heat-expandable microspheres to further improve the flame retardancy. At the same time, the introduction of the organic carbon-forming agent can improve the compatibility between the resin of the waterproof membrane and the microspheres and improve the dispersibility of the microspheres in the resin.

[0065] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments so that those skilled in the art can better understand and implement the technical solutions of the present invention, but the present invention is not limited to the scope of the examples.

[0066] Example 1

[0067] The lightweight waterproof roll provided in this embodiment includes a first resin layer and a second resin layer stacked in sequence, wherein the first resin layer and the second resin layer are PVC resin layers respectively.

[0068] The raw material formulas of the first resin layer and the second resin layer respectively include the following components by weight:

[0069]

[0070] In addition to the above components, heat-expandable microspheres are also added to the second resin layer, and the amount of the heat-expandable microspheres accounts for 1% of the total amount of raw materials used in the second resin layer.

[0071] The heat-expandable microspheres in this example include a core material and a shell wrapped around the core material. The core material contains hydrocarbons and a liquid phosphorus-containing flame retardant. The shell is an acrylic polymer, which is obtained by polymerizing monomers. The polymerized monomers include a first polymerized monomer and a second polymerized monomer. The first polymerized monomer is an acrylic phosphate monomer, and the second polymerized monomer is a combination of a nitrile monomer, a carboxyl acrylic monomer, and a methacrylate monomer.

[0072] The heat-expandable microspheres of this example were prepared by the following method:

[0073] (1) 450 g of water, 15 g of a water-dispersible halogen-free flame retardant, 80 g of an electrolyte, and 1.5 g of an emulsifier were mixed to obtain an aqueous dispersion, wherein the water-dispersible halogen-free flame retardant was magnesium hydroxide, the electrolyte was sodium chloride, and the emulsifier was sodium lauryl sulfate;

[0074] (2) 45 g of a first polymerizable monomer, 80 g of a second polymerizable monomer, 3 g of an initiator, 40 g of a hydrocarbon, and 15 g of a liquid phosphorus-containing flame retardant are mixed uniformly in a sealed ice-water bath to obtain an oil phase dispersion, wherein the first polymerizable monomer is methacrylic acid monophosphate, the second polymerizable monomer is a combination of ethoxyacrylonitrile, maleic acid, and methyl methacrylate in a mass ratio of 70:10:40, the initiator is benzoyl peroxide, the hydrocarbon is n-hexane, and the liquid phosphorus-containing flame retardant is dimethyl methyl phosphate;

[0075] (3) Under high-speed stirring, the oil phase dispersion was added to the aqueous phase dispersion and mixed evenly to obtain a pre-suspension. After nitrogen was passed through to deoxygenate, a high-pressure (pressure of 1.6 mPa, temperature of 70°C) polymerization reaction was carried out for 12 hours. After the reaction was completed, the suspension was filtered and dried at 50°C to obtain microspheres with a particle size of 20 μm.

[0076] The lightweight waterproof membrane in this example is prepared by the following method:

[0077] The raw materials of the first resin layer and the second resin layer are respectively added to a twin-screw extruder for melting, extruded through a multi-layer co-extrusion device, and then pulled, calendered, and cooled to obtain a waterproof membrane, wherein the extrusion temperature is 180°C and the screw speed is 130 rpm.

[0078] The thickness of the waterproof coiled material is 1.5 mm, the thickness of the first resin layer is 0.5 mm, and the thickness of the second resin layer is 1 mm.

[0079] Example 2

[0080] The waterproof roll provided in this embodiment is basically the same as that in embodiment 1, except that the amount of heat-expandable microspheres added to the second resin layer accounts for 0.5% of the total amount of raw materials used in the second resin layer.

[0081] The preparation matrix of the heat-expandable microspheres in this example is the same as that in Example 1, except that:

[0082] In step (1), the raw materials are 300 g of water, 5 g of aluminum hydroxide, 100 g of sodium chloride and 1.5 g of polyvinyl alcohol;

[0083] In step (2), the raw materials are 50 g of the first polymerizable monomer, 50 g of the second polymerizable monomer, 3 g of benzoyl peroxide, 30 g of n-heptane and 30 g of bisphenol A-bis(diphenyl phosphate), wherein the first polymerizable monomer is methacryloyloxyethyl phosphate, and the second polymerizable monomer is a combination of acrylonitrile, maleic acid and methyl methacrylate in a mass ratio of 50:15:20.

[0084] Finally, thermal expansion microspheres with a particle size of 25 μm were obtained.

[0085] Example 3

[0086] The lightweight waterproof membrane provided in this embodiment is basically the same as that in embodiment 1, except that:

[0087] The heat-expandable microspheres in this example are surface-modified heat-expandable microspheres, and the specific preparation method is as follows:

[0088] 10 g of an organic carbon-forming agent, 10 g of a nanocarbon material and 3 g of a silane coupling agent were added to 600 g of a dispersion medium to obtain a dispersion, and the mixture was evenly mixed. Then, 100 g of the microspheres prepared in Example 1 were added to the dispersion and mixed evenly. The mixture was kept warm at 60° C. for 24 h, allowed to stand, washed and filtered to obtain thermally expandable microspheres with a particle size of 30 μm, wherein the organic carbon-forming agent was an organophosphorus carbon-forming agent (triphenyl phosphate); the nanocarbon material was a commercially available acidified carbon nanotube (Pioneer Nano, carboxylated multi-walled carbon nanotube aqueous slurry); the silane coupling agent was γ-aminopropyltriethoxysilane; and the dispersion medium was ethanol.

[0089] Example 4

[0090] The lightweight waterproof membrane provided in this embodiment is basically the same as that in embodiment 3, except that:

[0091] The raw material formulas of the first resin layer and the second resin layer respectively include the following components by weight:

[0092]

[0093] In addition to the above components, the second resin layer also contains surface-modified heat-expandable microspheres, and the amount of the surface-modified heat-expandable microspheres accounts for 0.8% of the total amount of raw materials used in the second resin layer.

[0094] The preparation substrate of the surface-modified heat-expandable microspheres in this example is the same as that in Example 3, except that:

[0095] The raw materials include 10 g of organic carbon-forming agent (triphenyl phosphate), 5 g of nano-carbon material (Xianfeng Nano, carboxylated multi-walled carbon nanotube aqueous slurry) and 2 g of silane coupling agent.

[0096] Finally, surface-modified thermally expandable microspheres with a particle size of 28 μm were obtained.

[0097] Comparative Example 1

[0098] The waterproof membrane provided in this comparative example is basically the same as that in Example 1, except that no heat-expandable microspheres are added to the second resin layer.

[0099] Comparative Example 2

[0100] The waterproof roll provided in this comparative example is basically the same as that in Example 1, except that the amount of the heat-expandable microspheres in the second resin layer is 3% of the total amount of raw materials in the second resin layer.

[0101] Comparative Example 3

[0102] The waterproof roll provided in this comparative example is basically the same as that in Example 1, except that a carbonate foaming agent is used in place of heat-expandable microspheres in the second resin layer.

[0103] The mechanical properties of the waterproof membranes of Examples 1 to 4 and Comparative Examples 1 to 3 were tested according to GB 12952-2011, the density was tested according to GB / T 6343-2009, and the flame retardancy was tested according to GB / T 2408-2021 and GB / T 2406. The results are shown in Tables 1 and 2.

[0104] Table 1 Performance test results of waterproof membranes of Examples 1 to 4

[0105] Example 1 Example 2 Example 3 Example 4 tensile strength 11MPa 10.9MPa 10.5MPa 12MPa Elongation at break 270％ 265％ 259％ 280％ Density changes <![CDATA[-0.33g / cm 3 ]]> <![CDATA[-0.26g / cm 3 ]]> <![CDATA[-0.31g / cm 3 ]]> <![CDATA[-0.29g / cm 3 ]]> Vertical combustion UL-94 V-0 V-0 V-0 V-0 Limiting oxygen index 26.9％ 27.2％ 27.6％ 26.8％

[0106] Table 2 Performance test results of waterproof membranes of comparative examples 1 to 3

[0107] Comparative Example 1 Comparative Example 2 Comparative Example 3 tensile strength 15 MPa 8MPa 6MPa Elongation at break 310％ 135％ 110％ Density changes <![CDATA[0g / cm 3 ]]> <![CDATA[-0.41g / cm 3 ]]> <![CDATA[-0.28g / cm 3 <!-- 6 -->]]> Vertical combustion UL-94 V-1 V-0 V-2 Limiting oxygen index 27.1％ 22.1％ 18.8％

[0108] As shown in Tables 1 and 2, compared to the waterproof membrane without microspheres in Comparative Example 1, the solution proposed in the present invention effectively reduces the density of the waterproof membrane while maintaining the membrane's inherent flame retardancy and mechanical properties. In contrast, while increasing the microsphere content in Comparative Example 2 significantly reduces weight, the excessive porosity reduces flame retardancy and leads to a sharp drop in mechanical properties. The use of an inorganic blowing agent in Comparative Example 3 significantly reduces various properties due to the creation of open pores. Neither solution can simultaneously achieve density reduction while maintaining mechanical and flame retardancy.

[0109] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

[0110] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

Claims

1. A lightweight waterproof roll, comprising a first resin layer and a second resin layer stacked in sequence, characterized in that: Heat-expandable microspheres are added to the first resin layer or the second resin layer, the heat-expandable microspheres comprising a core material and a shell covering the core material, the core material comprising hydrocarbons and a liquid phosphorus-containing flame retardant, and the shell being an acrylic polymer obtained by polymerizing a monomer; The polymerizable monomers include a first polymerizable monomer and a second polymerizable monomer, wherein the first polymerizable monomer is an acrylic acid phosphate monomer, and the second polymerizable monomer is at least one of a nitrile monomer, a carboxyl acrylic acid monomer, and a methacrylic acid ester monomer; The first resin layer and the second resin layer are PVC resin layers, the heat-expandable microspheres are added to the second resin layer, and the amount of the heat-expandable microspheres is 0.5-1% of the total amount of raw materials of the second resin layer; The mass ratio of the first polymerizable monomer, the second polymerizable monomer, the hydrocarbon and the liquid phosphorus-containing flame retardant is 30-50:50-100:30-50:5-30.

2. The lightweight waterproof membrane according to claim 1, characterized in that: The thickness ratio of the first resin layer to the second resin layer is 5:1-15.

3. The lightweight waterproof membrane according to claim 1, characterized in that: The particle size of the thermally expandable microspheres is 10-80 μm.

4. The lightweight waterproof membrane according to claim 1, characterized in that: The raw materials of the first resin layer include PVC resin, plasticizer and filler; The raw materials of the second resin layer include PVC resin, heat-expandable microspheres, plasticizer and filler; In the first resin layer and the second resin layer, the mass ratio of the PVC resin, the plasticizer and the filler is 1:0.2 to 1:0.1 to 0.4; In the second resin layer, the amount of the heat-expandable microspheres is 0.5-1% of the total amount of raw materials of the second resin layer.

5. The lightweight waterproof membrane according to claim 4, characterized in that: The raw material formulas of the first resin layer and the second resin layer independently include: 80-100 parts of PVC resin; 20-80 parts of plasticizer; 15-30 parts of filler; The second resin layer further comprises heat-expandable microspheres in an amount of 0.5 to 1% of the total raw material amount of the second resin layer.

6. The lightweight waterproof membrane according to claim 5, characterized in that: The raw material formula of the first resin layer and the second resin layer further includes 2 to 6 parts of auxiliary agents, and the auxiliary agents are one or a combination of heat stabilizers and anti-ultraviolet agents.

7. The lightweight waterproof membrane according to claim 1, characterized in that: The acrylic acid phosphate monomer is one or a combination of acrylic acid monophosphate, acrylic acid diphosphate, methacrylic acid monophosphate, methacrylic acid diphosphate, pentabromobenzyl acrylate, methacryloyloxyethyl phosphate, and 2-hydroxyethyl methacrylate phosphate; and / or The nitrile monomer is one or a combination of acrylonitrile, methacrylonitrile, chloroacrylonitrile, and ethoxyacrylonitrile; and / or The carboxyl acrylic acid monomer is one or a combination of acrylic acid, methacrylic acid, and ethacrylic acid; and / or, The methacrylate monomer is one or a combination of methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, and benzyl methacrylate; and / or The hydrocarbon has a boiling point of 60° C. or above; and / or The liquid phosphorus-containing flame retardant is one or a combination of tributyl phosphate, dimethyl methyl phosphate, diethyl ethyl phosphate, tricresyl phosphate, diphenyl methyl phosphate, tri(xylene) phosphate, tri(butoxyethyl) phosphate, bisphenol A-bis(diphenyl phosphate) and resorcinol bis(diphenyl phosphate).

8. The lightweight waterproof membrane according to claim 1, characterized in that: The mass ratio of the nitrile monomer, the carboxyl acrylic monomer, and the methacrylate monomer is 50-100:5-15:20-50.

9. The lightweight waterproof membrane according to claim 1, characterized in that: The heat-expandable microspheres further include a water-dispersible halogen-free flame retardant dispersed in the core material and / or the shell.

10. The lightweight waterproof membrane according to claim 9, characterized in that: The water-dispersible halogen-free flame retardant is one or a combination of magnesium hydroxide, hydrated magnesium hydroxide, aluminum hydroxide, hydrated aluminum hydroxide, zinc oxide, and magnesium oxide; and / or the mass ratio of the water-dispersible halogen-free flame retardant to the liquid phosphorus-containing flame retardant is 5~20:5~30.

11. The lightweight waterproof membrane according to any one of claims 1 to 9, characterized in that: The heat-expandable microspheres are further subjected to surface modification treatment, which comprises dispersing unmodified heat-expandable microspheres into a dispersion liquid containing an organic carbon-forming agent, nano-carbon materials and a coupling agent to obtain surface-modified heat-expandable microspheres.

12. The lightweight waterproof membrane according to claim 11, characterized in that: The mass ratio of the organic carbon-forming agent to the inorganic carbon material is 1:0.5-1.5; and / or, The organic carbon-forming agent is one or a combination of an organic phosphorus carbon-forming agent, a thermoplastic phenolic resin carbon-forming agent, a polyamide carbon-forming agent, a triazine derivative carbon-forming agent and a hyperbranched macromolecular flame-retardant carbon-forming agent; and / or, The nano-carbon material is one or a combination of carbon nanotubes and graphene; and / or, The coupling agent is a silane coupling agent; and / or, The mass ratio of the unmodified thermally expandable microspheres to the organic carbon-forming agent is 10-50:1-5.

13. The lightweight waterproof membrane according to claim 11, characterized in that: The preparation method of the surface-modified heat-expandable microspheres comprises the following steps: (1) uniformly mixing water, a water-dispersible halogen-free flame retardant, an electrolyte and an emulsifier to obtain an aqueous dispersion; (2) uniformly mixing the first polymerizable monomer, the second polymerizable monomer, the initiator, the hydrocarbon compound and the liquid phosphorus-containing flame retardant to obtain an oil phase dispersion; (3) adding the oil phase dispersion to the aqueous phase dispersion under stirring to obtain a presuspension, and then polymerizing under inert gas conditions to obtain surface-unmodified thermally expandable microspheres; (4) Dispersing the surface-unmodified heat-expandable microspheres in a dispersion containing an organic carbon-forming agent, a nanocarbon material, and a coupling agent to obtain the surface-modified heat-expandable microspheres.

14. A method for preparing the lightweight waterproof roll according to any one of claims 1 to 13, characterized in that: The preparation method comprises melting the raw material of the first resin layer and the raw material of the second resin layer respectively, and co-extruding them to obtain the lightweight waterproof coiled material.

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