Composite low-temperature-resistant modified asphalt waterproof coiled material and preparation method thereof

Abstract

The invention relates to a composite low-temperature-resistant modified asphalt waterproof coiled material and a preparation method thereof, and relates to the field of waterproof materials, the composite low-temperature-resistant modified asphalt waterproof coiled material comprises a polyester base layer, modified asphalt layers coated on the two surfaces of the base layer, a heat preservation layer compounded on the surface of the upper modified asphalt layer, and an isolation layer covering the surfaces of the heat preservation layer and the lower modified asphalt layer; the thermal insulation layer is formed by bonding and compounding aluminum silicate fiber felt and closed cell perlite particles through organic silicon resin, the thickness of the thermal insulation layer is 0.8-1.5 mm, the particle size of the closed cell perlite particles is 0.1-0.3 mm, and the mass of the closed cell perlite particles accounts for 40-50% of the mass of the thermal insulation layer. According to the waterproof coiled material, an asphalt modification system is optimized, a low-temperature toughening agent is introduced, the bending strain of modified asphalt at the temperature of-40 DEG C is larger than or equal to 30%, the brittle point is smaller than or equal to-45 DEG C, the flexibility and the brittle resistance of the coiled material at the extremely low temperature are effectively improved, the heat preservation layer is formed by compositing aluminum silicate fiber felt and closed cell perlite particles, the heat conductivity coefficient and the water absorption rate are reduced, and the waterproof coiled material is good in heat preservation performance. In addition, the heat-preservation and heat-insulation effect is enhanced, and the material is firmly bonded with the modified asphalt layer and is not easy to peel.

Description

Technical Field

[0001] The present invention relates to the field of waterproof materials, and in particular to a composite low-temperature-resistant modified asphalt waterproof roll and a preparation method thereof. Background Art

[0002] Modified asphalt waterproofing membranes are widely used due to their excellent waterproofing properties and ease of construction. With the increasing demand for weather resistance in construction projects, especially in cold regions or low-temperature environments, the development of composite waterproofing membranes that combine excellent low-temperature resistance with comprehensive mechanical properties has become an important research direction. Composite low-temperature-resistant modified asphalt waterproofing membranes are usually designed by optimizing the asphalt modification system, composite reinforced base, and functional coating to meet the requirements of crack resistance, thermal insulation, and long-term durability in low-temperature environments. The core of this is to improve the membrane's flexibility and brittleness resistance under low-temperature conditions below -40°C through the synergistic effect of the material components, while ensuring compatibility during construction and the stability of the finished product.

[0003] However, existing low-temperature-resistant modified asphalt waterproofing membranes still have limitations in practical application. For example, conventional modified asphalt systems struggle to achieve a flexural strain exceeding 30% at extremely low temperatures, and their brittle point is often above -40°C, making them susceptible to cracking and failure in extremely cold environments. The insulation layer often utilizes a single fiber or granular material, which exhibits high thermal conductivity and high water absorption, and the bond interface with the modified asphalt layer is susceptible to delamination due to environmental stress. During the composite process, the impregnation effect of the base and asphalt layers, as well as the lamination and shaping parameters of the insulation and asphalt layers, lack precise control, which can lead to insufficient uniformity in the overall performance of the membrane. Furthermore, the compatibility between the flexibility and debonding properties of existing insulation materials at low temperatures needs to be improved, and the curing process in some processes is energy-intensive and inefficient. To address these technical bottlenecks, innovations are urgently needed in optimizing material composition, structural composite processes, and production process control. To this end, we propose a composite low-temperature-resistant modified asphalt waterproofing membrane and its preparation method. Summary of the Invention

[0004] In response to the technical problems existing in the prior art, the present invention provides a composite low-temperature resistant modified asphalt waterproof membrane and a preparation method thereof. This technical solution solves the above-mentioned shortcomings of the existing low-temperature resistant modified asphalt waterproof membrane: traditional modified asphalt has limited low-temperature performance, the bending strain is difficult to reach more than 30%, the brittle point is high and it is easy to crack; the insulation layer material is defective and the bonding interface with the asphalt layer is easy to peel off; insufficient control of the composite process leads to uneven performance; the low-temperature performance of the isolation layer needs to be improved, and some curing processes have high energy consumption and low efficiency.

[0005] The present invention solves the above-mentioned technical problems with the following technical solution: a composite low-temperature-resistant modified asphalt waterproof membrane, comprising a polyester base layer, a modified asphalt layer coated on both sides of the base layer, a thermal insulation layer composited on the surface of the upper modified asphalt layer, and an isolation layer covering the surface of the thermal insulation layer and the lower modified asphalt layer; The insulation layer is made of aluminum silicate fiber felt and closed-cell perlite particles bonded by silicone resin, with a thickness of 0.8-1.5 mm. The closed-cell perlite particles have a particle size of 0.1-0.3 mm and account for 40-50% of the insulation layer's mass. The modified asphalt layer comprises the following components: 60-70 parts of 90# petroleum asphalt, 8-12 parts of SBS modifier, 15-20 parts of modified bentonite-basalt fiber composite filler, 3-5 parts of naphthenic oil, and 0.5-1 part of antioxidant RD; The isolation layer comprises an upper isolation layer and a lower isolation layer. The upper isolation layer is a biaxially oriented polyethylene film with a thickness of 0.15-0.25 mm, and the lower isolation layer is a polyethylene aluminum-plated film with a thickness of 0.05-0.1 mm.

[0006] Preferably, in the preparation process of the modified bentonite-basalt fiber composite filler, the bentonite is selected from sodium bentonite, with a calcium content of ≤1.5% and a cation exchange capacity of ≥70mmol / 100g; The diameter of basalt fiber monofilament is 12-15μm, and the tensile strength is ≥3000MPa; The silane coupling agent KH-570 is added as follows: first dilute it with anhydrous ethanol to a concentration of 10wt%, then spray it into the mixed system, and control the stirring temperature at 110-120℃.

[0007] Preferably, the organic silicone resin in the thermal insulation layer is methylphenyl silicone resin, with a solid content of ≥85% and a viscosity of 500-800 mPa·s; The preparation of closed-cell perlite particles includes: crushing the perlite ore to 0.5-1mm, expanding it at 850℃, spraying the surface with an aqueous solution containing 5wt% silica sol, and secondary sintering at 600℃ to form a closed-cell structure with a true density of ≤120kg / m³ and a water absorption rate of ≤5%. The gram weight of aluminum silicate fiber felt is 150-200g / m², and the thermal conductivity coefficient is ≤0.035W / (m·K).

[0008] Preferably, the surface of the biaxially oriented polyethylene film of the upper isolation layer is corona treated, with a dyne value of ≥38 mN / m, and is coated with an isolation coating, which is composed of the following components: 40-50 parts by weight of talc, 10-15 parts by weight of nano-calcium carbonate, 3-5 parts by weight of hydrogenated castor oil derivative, and 30-40 parts by weight of polyurethane acrylate emulsion; The dry film thickness of the coating is 10-15μm.

[0009] Preferably, the polyester base layer is a long-fiber polyester non-woven fabric with a gram weight of ≥180g / m², a longitudinal tensile strength of ≥800N / 50mm, and a transverse tensile strength of ≥700N / 50mm; The tire base is first immersed in a pretreatment liquid, which contains: 20-30 parts by weight of epoxy resin emulsion, 2-3 parts by weight of silane coupling agent KH-550, and 0.5-1 part by weight of penetrant JFC.

[0010] Preferably, a low-temperature toughening agent is added to the modified asphalt layer, and the toughening agent is a maleic anhydride grafted hydrogenated styrene-butadiene block copolymer, with a grafting rate of ≥1.2% and an addition amount of 3-5% of the total mass of the asphalt; The bending strain of modified asphalt at -40℃ is ≥30%, and the brittle point is ≤-45℃.

[0011] A method for preparing a composite low-temperature resistant modified asphalt waterproofing membrane, for realizing the composite low-temperature resistant modified asphalt waterproofing membrane, comprises the following steps: S1. Preparation of modified bentonite-basalt fiber composite filler: Bentonite was soaked in a 5wt% hydrochloric acid solution for 2 hours, washed to neutrality, calcined at 550°C for 3 hours, and ball-milled to a particle size of ≤10 μm; basalt fiber was treated with a 10wt% sodium hydroxide solution at 40°C for 30 minutes, washed, dried, and cut into 3-5 mm short fibers; bentonite powder and basalt short fibers were mixed in a mass ratio of 2:1, 3% of the total amount of silane coupling agent KH-570 was added, and the mixture was modified by high-speed stirring for 20 minutes to obtain a composite filler; S2. Preparation of modified asphalt: Heat 90# petroleum asphalt to 160-170°C, add naphthenic oil and stir for 10 minutes, then add SBS modifier, antioxidant RD and the composite filler obtained in step S1 in sequence, react at a shear rate of 1800 rpm for 2 hours, and mature at 175°C for 3 hours to obtain modified asphalt; S3, coil forming: preheat the polyester base with 180°C heat-conducting oil, and impregnate both sides with the modified asphalt obtained in step S2, controlling the coating thickness to 1.5-2.0mm; when the coating layer is not cured, lay the upper surface with a prefabricated insulation layer, which is made of aluminum silicate fiber felt impregnated with silicone resin and then sprinkled with closed-cell perlite particles, and is shaped by roller pressing at a pressure of 0.8-1.2MPa; finally, coat both sides with an isolation film, and cure by a three-stage gradient heating process of 40°C → 80°C → 110°C, and then roll up to obtain the finished product.

[0012] Preferably, the aging process of the modified asphalt in step S2 adopts segmented temperature control: the first stage is kept at 170°C for 1 hour, the second stage is kept at 175°C for 1.5 hours, and the third stage is cooled to 165°C and kept for 0.5 hours; the shearing equipment is a high-speed colloid mill, the grinding disc gap is controlled at 0.1-0.2mm, and the material circulation number is ≥5 times.

[0013] Preferably, the preparation of the thermal insulation layer prefabricated member in step S3 specifically includes: The aluminum silicate fiber felt is impregnated with a silicone resin emulsion with a solid content of 40%, and the rubber content is controlled to 60-70% by rollers. Closed-cell perlite particles are evenly spread on the surface of the impregnated felt with a spreading density of 800-1000g / m². The felt is then pre-pressed for 1 minute in a double-roll hot press at 130°C and 0.8MPa to set the shape. The three-stage gradient temperature rise curing parameters of step S3 are: the first stage is 40°C ± 2°C and maintained for 2 hours, the second stage is heated to 80°C at a rate of 1°C / min and maintained for 3 hours, and the third stage is heated to 110°C at a rate of 0.5°C / min and maintained for 1 hour; the curing process is carried out under tension control, and the longitudinal tension of the coil is ≤50N / 50mm.

[0014] Preferably, the laminating process of the lower isolation layer polyethylene aluminum film in step S3 includes: Apply a hot melt adhesive layer on the aluminum-plated surface. The adhesive layer consists of ethylene-vinyl acetate copolymer and petroleum resin in a ratio of 7:3, with a coating amount of 15-20g / m². Then, use a hot press roller to compound it with the modified asphalt layer at 100-110℃ and 0.3-0.5MPa. It also includes post-processing steps: the coiled material is cross-linked by gamma ray irradiation, with an irradiation dose of 8-12kGy and a dose rate of 1.5-2.0kGy / h; after irradiation, it is placed in a 50℃ curing room for 48 hours, with a relative humidity of ≤30%.

[0015] The beneficial effects of the present invention are as follows: the waterproof roll material optimizes the asphalt modification system and introduces a low-temperature toughening agent, so that the bending strain of the modified asphalt at -40°C is ≥30%, and the brittle point is ≤-45°C, which effectively improves the flexibility and brittleness resistance of the roll material at extremely low temperatures. The thermal insulation layer is composited with aluminum silicate fiber felt and closed-cell perlite particles, which reduces the thermal conductivity and water absorption, enhances the thermal insulation effect, and is firmly bonded to the modified asphalt layer and is not easy to peel off. In the composite process, the uniformity of the overall performance of the roll material is ensured by precisely controlling the impregnation effect of the base and the asphalt layer, and the pressing and shaping parameters of the thermal insulation layer and the asphalt layer. The isolation layer material exhibits good flexibility and peeling performance at low temperatures, and the preparation method adopts three-stage gradient heating and curing, which reduces energy consumption, improves production efficiency, ensures the stability of the finished product of the roll material, and meets the waterproofing needs in cold areas or low-temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of the present invention; Figure 2 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0018] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of this application, "plurality" means two or more, unless otherwise specifically specified.

[0019] In the description of this application, the term "for example" is used to mean "used as an example, illustration or explanation". Any embodiment described as "for example" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is given to enable any person skilled in the art to implement and use the present invention. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art will recognize that the present invention can be implemented without using these specific details. In other examples, well-known structures and processes will not be elaborated in detail to avoid obscuring the description of the present invention with unnecessary details. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in this application.

[0020] Example 1, a composite low temperature resistant modified asphalt waterproof membrane, reference Figure 1As shown, the structure comprises a polyester base layer, a modified asphalt layer applied to both sides of the base layer, an insulation layer laminated to the upper modified asphalt layer, and a barrier layer covering both the insulation layer and the lower modified asphalt layer. The insulation layer is composed of aluminum silicate fiber felt bonded to closed-cell perlite particles with a silicone resin. Its thickness ranges from 0.8-1.5mm, and the closed-cell perlite particles are 0.1-0.3mm in size, accounting for 40-50% of the insulation layer's mass. Specifically, the closed-cell perlite particles are prepared by crushing the raw perlite to a particle size of 0.5-1mm, subjecting it to high-temperature expansion at 850°C. An aqueous solution containing 5wt% silica sol is then sprayed onto the surface of the particles, followed by a secondary sintering process at 600°C to create a closed-cell structure. The resulting closed-cell perlite particles have a true density of ≤120kg / m³ and a water absorption rate of ≤5%. The weight of aluminum silicate fiber felt is 150-200g / m², the thermal conductivity is ≤0.035W / (m·K), and the silicone resin used is methyl phenyl silicone resin with a solid content of ≥85% and a viscosity of 500-800mPa·s.

[0021] The modified asphalt layer contains the following components: 60-70 parts of 90# petroleum asphalt, 8-12 parts of SBS modifier, 15-20 parts of modified bentonite-basalt fiber composite filler, 3-5 parts of cyclohexane oil, 0.5-1 part of antioxidant RD, and a low-temperature toughening agent is added. The toughening agent is a maleic anhydride grafted hydrogenated styrene-butadiene block copolymer with a grafting rate of ≥1.2%. The addition amount is 3-5% of the total mass of the asphalt, so that the bending strain of the modified asphalt at -40°C is ≥30% and the brittle point is ≤-45°C. The preparation process of the modified bentonite-basalt fiber composite filler is as follows: sodium bentonite with a calcium content of ≤1.5% and a cation exchange capacity of ≥70mmol / 100g is selected, and it is first soaked in a 5wt% hydrochloric acid solution for 2 hours, washed with water until the solution is neutral, and then calcined at 550℃ for 3 hours, and then ball-milled to a particle size of ≤10μm; the basalt fiber monofilament has a diameter of 12-15μm and a tensile strength of ≥3000MPa, and is treated with a 10wt% sodium hydroxide solution at 40℃ for 30 minutes, washed and dried, and cut into 3-5mm short fibers; then the bentonite powder and the basalt short fibers are mixed in a mass ratio of 2:1, and a silane coupling agent KH-570 accounting for 3% of the total amount is added (the coupling agent is first diluted to 10wt% with anhydrous ethanol). The mixture was added into the mixed system by spraying, and the stirring temperature was controlled at 110-120°C and the mixture was modified by high-speed stirring for 20 minutes to obtain a composite filler.

[0022] The isolation layer includes an upper isolation layer and a lower isolation layer. The upper isolation layer is a biaxially oriented polyethylene film with a thickness of 0.15-0.25mm. Its surface is corona treated, and the dyne value is ≥38mN / m. It is coated with an isolation coating, which is composed of 40-50 parts by weight of talc powder, 10-15 parts by weight of nano calcium carbonate, 3-5 parts by weight of hydrogenated castor oil derivatives, and 30-40 parts by weight of polyurethane acrylate emulsion. The dry film thickness of the coating is 10-15μm; the lower isolation layer is a polyethylene aluminum-plated film with a thickness of 0.05-0.1mm.

[0023] The polyester base layer is a long-fiber polyester non-woven fabric with a grammage of ≥180g / m², a longitudinal tensile strength of ≥800N / 50mm, and a transverse tensile strength of ≥700N / 50mm. The base is first impregnated with a pretreatment solution containing 20-30 parts by weight of epoxy resin emulsion, 2-3 parts by weight of silane coupling agent KH-550, and 0.5-1 part by weight of penetrant JFC.

[0024] Example 2, reference Figure 2 As shown, the preparation method of the composite low-temperature resistant modified asphalt waterproof membrane is as follows: First, the modified bentonite-basalt fiber composite filler is prepared. As mentioned above, the bentonite is treated according to the above steps and then mixed with the basalt short fibers and modified.

[0025] Next, to prepare the modified asphalt, 90# petroleum asphalt was heated to 160-170°C, naphthenic oil was added, and stirred at an appropriate speed for 10 minutes. The SBS modifier, antioxidant RD, and the prepared composite filler were then added in sequence. The mixture was then subjected to a high-speed colloid mill at a shear rate of 1800 rpm for two hours, with a grinding disc gap of 0.1-0.2 mm and a material recycle cycle of ≥5 times. The aging process employed staged temperature control: the first stage was held at 170°C for one hour, the second stage was raised to 175°C and held for 1.5 hours, and the third stage was cooled to 165°C and held for 0.5 hours, ultimately yielding the modified asphalt.

[0026] The coil is then formed. The polyester base is preheated with 180°C heat-conducting oil and then impregnated on both sides with the prepared modified asphalt, with a coating thickness of 1.5-2.0mm. The insulation preform is prepared by impregnating aluminum silicate fiber felt with a 40% solids silicone resin emulsion, controlled to a 60-70% adhesive content by rollers. Closed-cell perlite particles are evenly spread on the surface of the impregnated felt at a density of 800-1000g / m². The preform is then pre-pressed for one minute in a twin-roll hot press at 130°C and 0.8MPa to set the shape. While the modified asphalt coating is still uncured, the insulation preform is placed on the upper surface and rolled at a pressure of 0.8-1.2MPa to set the shape. The lamination process for the lower insulating layer of polyethylene aluminized film is as follows: a hot-melt adhesive layer composed of ethylene-vinyl acetate copolymer and petroleum resin in a ratio of 7:3 is applied to the aluminized surface at a coating weight of 15-20g / m². The adhesive is then laminated with the modified asphalt layer using hot-pressing rollers at 100-110°C and 0.3-0.5MPa. Finally, the insulating film is laminated on both sides and subjected to a three-stage gradient temperature curing process. The first stage is held at 40°C ± 2°C for 2 hours; the second stage is heated at a rate of 1°C / min to 80°C for 3 hours; and the third stage is heated at a rate of 0.5°C / min to 110°C for 1 hour. The curing process is tension-controlled, with the longitudinal tension of the coil ≤50N / 50mm.

[0027] Finally, the coiled material is subjected to post-processing, and is cross-linked by γ-ray irradiation with a dose of 8-12 kGy and a dose rate of 1.5-2.0 kGy / h. After irradiation, the coiled material is placed in a 50°C curing room for 48 hours with a relative humidity of ≤30% to obtain the finished product.

[0028] During the preparation of the modified bentonite-basalt fiber composite filler, the acidification, calcination, and ball milling of the sodium bentonite and the alkaline treatment of the basalt fiber effectively enhance the filler's surface activity. The spray modification with a silane coupling agent enhances the compatibility between the filler and asphalt, laying the foundation for subsequent performance optimization of the modified asphalt. During the preparation of the modified asphalt, precise control of the heating temperature, high-speed colloid mill shear rate, and number of cycles ensures the full dispersion and fusion of the components. A staged temperature-controlled aging process ensures a thorough modification reaction, enhances the stability of the asphalt system, and ensures the membrane's flexibility and crack resistance in low-temperature environments. During the roll forming process, the polyester base is preheated and then impregnated on both sides with modified asphalt to promote a strong bond between the base and the asphalt layer, enhancing the overall mechanical properties of the roll. The preformed insulation layer is impregnated with adhesive, sprinkled with perlite, and hot-pressed to form a structurally stable insulation layer. While still uncured, it is rolled and bonded to the modified asphalt layer to ensure interfacial adhesion. The lower barrier layer utilizes a specifically formulated hot-melt adhesive and hot-pressing process to ensure a secure bond between the barrier film and the roll and facilitates removal during installation. A three-stage gradient temperature curing process precisely controls the heating rate and temperature to avoid stress concentration within the roll, improving dimensional stability and durability. Tension control prevents roll deformation. Post-processing involves gamma-ray cross-linking to further improve the roll's molecular structure, enhancing weather resistance and chemical stability. A curing treatment ensures stable performance. Each step of the overall process is closely linked. Through scientific parameter control and process design, efficient bonding and synergistic performance between the roll layers are achieved, ensuring the product's superior performance in low-temperature resistance, adhesion, durability, and ease of installation.

[0029] It should be noted that, in the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0030] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0031] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A composite low-temperature resistant modified asphalt waterproof membrane, characterized in that: It includes a polyester tread base layer, a modified asphalt layer coated on both sides of the tread base layer, a thermal insulation layer compounded on the surface of the upper modified asphalt layer, and an isolation layer covering the surface of the thermal insulation layer and the lower modified asphalt layer; The insulation layer is made of aluminum silicate fiber felt and closed-cell perlite particles bonded by silicone resin, with a thickness of 0.8-1.5 mm. The closed-cell perlite particles have a particle size of 0.1-0.3 mm and account for 40-50% of the insulation layer's mass. The modified asphalt layer comprises the following components: 60-70 parts of 90# petroleum asphalt, 8-12 parts of SBS modifier, 15-20 parts of modified bentonite-basalt fiber composite filler, 3-5 parts of naphthenic oil, and 0.5-1 part of antioxidant RD; The isolation layer comprises an upper isolation layer and a lower isolation layer. The upper isolation layer is a biaxially oriented polyethylene film with a thickness of 0.15-0.25 mm, and the lower isolation layer is a polyethylene aluminum-plated film with a thickness of 0.05-0.1 mm.

2. The composite low-temperature resistant modified asphalt waterproof membrane according to claim 1, characterized in that: In the preparation process of the modified bentonite-basalt fiber composite filler, the bentonite is selected from sodium bentonite, the calcium content is ≤1.5%, and the cation exchange capacity is ≥70mmol / 100g; The diameter of basalt fiber monofilament is 12-15μm, and the tensile strength is ≥3000MPa; The silane coupling agent KH-570 is added as follows: first dilute it with anhydrous ethanol to a concentration of 10wt%, then spray it into the mixed system, and control the stirring temperature at 110-120℃.

3. The composite low-temperature resistant modified asphalt waterproof membrane according to claim 1, characterized in that: The organic silicone resin in the thermal insulation layer is methylphenyl silicone resin, with a solid content of ≥85% and a viscosity of 500-800mPa·s; The preparation of closed-cell perlite particles includes: crushing the perlite ore to 0.5-1mm, expanding it at 850℃, spraying the surface with an aqueous solution containing 5wt% silica sol, and secondary sintering at 600℃ to form a closed-cell structure with a true density of ≤120kg / m³ and a water absorption rate of ≤5%. The gram weight of aluminum silicate fiber felt is 150-200g / m², and the thermal conductivity coefficient is ≤0.035W / (m·K).

4. The composite low-temperature resistant modified asphalt waterproof membrane according to claim 1, characterized in that: The surface of the upper isolation layer biaxially oriented polyethylene film is corona treated, with a dyne value of ≥38mN / m, and is coated with an isolation coating, which is composed of the following components: 40-50 parts by weight of talc, 10-15 parts by weight of nano-calcium carbonate, 3-5 parts by weight of hydrogenated castor oil derivative, and 30-40 parts by weight of polyurethane acrylate emulsion; The dry film thickness of the coating is 10-15μm.

5. The composite low-temperature resistant modified asphalt waterproof membrane according to claim 1, characterized in that: The polyester base layer is a long-fiber polyester non-woven fabric with a gram weight of ≥180g / m², a longitudinal tensile strength of ≥800N / 50mm, and a transverse tensile strength of ≥700N / 50mm; The tire base is first immersed in a pretreatment liquid, which contains: 20-30 parts by weight of epoxy resin emulsion, 2-3 parts by weight of silane coupling agent KH-550, and 0.5-1 part by weight of penetrant JFC.

6. The composite low-temperature resistant modified asphalt waterproof membrane according to claim 1, characterized in that: A low-temperature toughening agent is added to the modified asphalt layer, wherein the toughening agent is a maleic anhydride grafted hydrogenated styrene-butadiene block copolymer, with a grafting rate of ≥1.2% and an addition amount of 3-5% of the total mass of the asphalt; The bending strain of modified asphalt at -40℃ is ≥30%, and the brittle point is ≤-45℃.

7. A method for preparing a composite low-temperature resistant modified asphalt waterproof membrane, characterized in that: The method for realizing a composite low-temperature resistant modified asphalt waterproof membrane as claimed in any one of claims 1 to 6 comprises the following steps: S1. Preparation of modified bentonite-basalt fiber composite filler: Bentonite was soaked in a 5wt% hydrochloric acid solution for 2 hours, washed to neutrality, calcined at 550°C for 3 hours, and ball-milled to a particle size of ≤10 μm; basalt fiber was treated with a 10wt% sodium hydroxide solution at 40°C for 30 minutes, washed, dried, and cut into 3-5 mm short fibers; bentonite powder and basalt short fibers were mixed in a mass ratio of 2:1, 3% of the total amount of silane coupling agent KH-570 was added, and the mixture was modified by high-speed stirring for 20 minutes to obtain a composite filler; S2. Preparation of modified asphalt: Heat 90# petroleum asphalt to 160-170°C, add naphthenic oil and stir for 10 minutes, then add SBS modifier, antioxidant RD and the composite filler obtained in step S1 in sequence, react at a shear rate of 1800 rpm for 2 hours, and mature at 175°C for 3 hours to obtain modified asphalt; S3, coil forming: preheat the polyester base with 180°C heat-conducting oil, and impregnate both sides with the modified asphalt obtained in step S2, controlling the coating thickness to 1.5-2.0mm; when the coating layer is not cured, lay the upper surface with a prefabricated insulation layer, which is made of aluminum silicate fiber felt impregnated with silicone resin and then sprinkled with closed-cell perlite particles, and is shaped by roller pressing at a pressure of 0.8-1.2MPa; finally, coat both sides with an isolation film, and cure by a three-stage gradient heating process of 40°C → 80°C → 110°C, and then roll up to obtain the finished product.

8. The method for preparing a composite low-temperature resistant modified asphalt waterproof membrane according to claim 7, characterized in that: The aging process of the modified asphalt in step S2 adopts segmented temperature control: the first stage is kept at 170°C for 1 hour, the second stage is kept at 175°C for 1.5 hours, and the third stage is cooled to 165°C and kept for 0.5 hours; the shearing equipment is a high-speed colloid mill, the grinding disc gap is controlled at 0.1-0.2mm, and the material circulation number is ≥5 times.

9. The method for preparing a composite low-temperature resistant modified asphalt waterproof membrane according to claim 7, characterized in that: The preparation of the thermal insulation layer prefabricated member in step S3 specifically includes: The aluminum silicate fiber felt is impregnated with a silicone resin emulsion with a solid content of 40%, and the rubber content is controlled to 60-70% by rollers. Closed-cell perlite particles are evenly spread on the surface of the impregnated felt with a spreading density of 800-1000g / m². The felt is then pre-pressed for 1 minute in a double-roll hot press at 130°C and 0.8MPa to set the shape. The three-stage gradient temperature rise curing parameters of step S3 are: the first stage is 40°C ± 2°C and maintained for 2 hours, the second stage is heated to 80°C at a rate of 1°C / min and maintained for 3 hours, and the third stage is heated to 110°C at a rate of 0.5°C / min and maintained for 1 hour; the curing process is carried out under tension control, and the longitudinal tension of the coil is ≤50N / 50mm.

10. The method for preparing a composite low-temperature resistant modified asphalt waterproof membrane according to claim 7, characterized in that: The composite process of the lower isolation layer polyethylene aluminum film in step S3 includes: Apply a hot melt adhesive layer on the aluminum-plated surface. The adhesive layer consists of ethylene-vinyl acetate copolymer and petroleum resin in a ratio of 7:3, with a coating amount of 15-20g / m². Then, use a hot press roller to compound it with the modified asphalt layer at 100-110℃ and 0.3-0.5MPa. It also includes post-processing steps: the coiled material is cross-linked by gamma ray irradiation, with an irradiation dose of 8-12kGy and a dose rate of 1.5-2.0kGy / h; after irradiation, it is placed in a 50℃ curing room for 48 hours, with a relative humidity of ≤30%.

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