Environment-friendly plant asphalt waterproofing membrane and preparation method thereof

Abstract

This invention discloses an environmentally friendly plant-based bitumen waterproof membrane and its preparation method. The waterproof membrane comprises a blended modified bitumen, and is composed of the following components by mass percentage: 40%–60% plant-based bitumen, 20%–30% petroleum bitumen, 3%–8% SBS, 2%–5% SBR, 1%–3% modifier, and 5%–10% filler. The preparation method includes: heating the plant-based bitumen to 90–110°C and adding the modifier for pretreatment; mixing with petroleum bitumen and then adding SBS and SBR, followed by high-speed shear blending at 160–180°C using a colloid mill; adding filler and mixing thoroughly before coating onto a base fabric. This invention significantly improves the compatibility of plant-based bitumen with petroleum bitumen through synergistic modification with SBS and SBR, combined with the modifier, achieving a high proportion of plant-based bitumen substitution. The resulting membrane exhibits excellent mechanical properties and weather resistance, and significant environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of building waterproofing materials technology, specifically an environmentally friendly plant-based bitumen waterproof membrane and its preparation method. Background Technology

[0002] Currently, the core raw material of the asphalt waterproof membranes widely used in building waterproofing projects is petroleum asphalt. However, traditional petroleum asphalt faces two major challenges: Firstly, there is the issue of resource dependence and cost pressure. Petroleum asphalt is highly dependent on non-renewable petroleum resources. With the increasing depletion of global oil resources, the supply stability of petroleum asphalt is severely affected, and its price is trending upward in the long term. This over-reliance on fossil resources not only fails to meet the requirements of sustainable development but also brings continuous raw material cost pressure to waterproof membrane manufacturers.

[0003] Secondly, there is environmental pressure. The "Emission Standard of Pollutants for Building Waterproofing Membrane Industry" (GB 36287-2025), implemented in 2025, significantly tightens VOCs emission limits, placing enormous pressure on existing production processes for environmental upgrades. Furthermore, the Ministry of Housing and Urban-Rural Development's "Evaluation Standard for Green Buildings" (GB / T 50378-2019) adds requirements for calculating the carbon footprint of building materials, and petroleum asphalt membranes face usage restrictions due to their high carbon emissions.

[0004] To address these issues, developing renewable, low-pollution plant-based bitumen has become a crucial direction for the industry's green transformation. Plant-based bitumen (such as bitumen prepared from byproducts of vegetable oil processing, such as cottonseed oil and waste cooking oil) can not only reduce dependence on fossil resources but also significantly reduce energy consumption and carbon emissions during production. However, the application of plant-based bitumen in waterproof membranes still faces significant technical bottlenecks in current technologies.

[0005] First, the amount of plant-based bitumen added is limited. Plant-based bitumen is mainly composed of heavy oils, lignin, cellulose, hemicellulose, and other biomass components, which are prone to degradation, aging, and performance deterioration under ultraviolet radiation, rainwater, and high and low temperature cycles. Therefore, the amount of plant-based bitumen added is inversely proportional to its durability, and the amount of plant-based bitumen added in existing waterproof membranes is usually no more than 15%. This low addition severely limits the environmental benefits and application value of plant-based bitumen in waterproof membranes. For example, Chinese patent CN120945663A discloses an ultra-weather-resistant plant-based bitumen waterproof membrane. Although its bitumen mixture uses 75% modified cottonseed oil bitumen and 25% petroleum-based bitumen, this scheme relies on pine fiber to absorb naphthenic oil to inhibit oil volatilization. The process is complex and the improvement in weather resistance is limited, failing to fundamentally improve the compatibility problem between plant-based bitumen and petroleum bitumen.

[0006] Second, poor compatibility. Plant-based asphalt is rich in polar oxygen-containing groups (carboxyl and hydroxyl groups), resulting in strong intermolecular forces, while petroleum asphalt is mainly composed of non-polar components. The significant difference in polarity between the two leads to poor compatibility between plant-based and petroleum asphalt. Poor compatibility not only limits the substitution ratio of plant-based asphalt but also seriously affects the overall performance of the final product.

[0007] Third, existing modification methods are not effective. There have been attempts to modify bitumen using a combination of SBS and SBR. For example, Chinese patent CN113652095A discloses an SBS+SIS dual-elastomer modified bitumen waterproof membrane, and existing technologies also document SBS+SBR combination modification. Furthermore, the use of silane coupling agents to improve the compatibility of components in bitumen systems is a known technique in this field. However, most of these modification methods are developed for petroleum bitumen systems. When applied to plant-based bitumen systems, the poor swelling effect of plant-based bitumen on SBS makes it difficult to evenly disperse the modifier, easily leading to the formation of large molecular rubber aggregates with a diameter of up to 50 μm. This significantly reduces the modification effect and fails to meet the requirements for waterproof membrane use.

[0008] Fourth, the technical route for bio-based modified bitumen is still immature. For example, patent CN121290859A discloses a pre-laid polymer waterproof membrane of bio-based modified bitumen with penetrating crystallization. Its technical solution relies on the combination of modified isocyanate polymer and penetrating crystal sand layer. The technical route is completely different from that of this application. Moreover, the process is complicated and the cost is high, which is not conducive to large-scale promotion and application.

[0009] In summary, the application of plant bitumen in waterproof membranes in the existing technology is mainly limited by technical problems such as low doping amount, poor compatibility, and poor modification effect. There is an urgent need to develop an environmentally friendly plant bitumen waterproof membrane and its preparation method that can achieve a high proportion of plant bitumen substitution and has excellent performance. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an environmentally friendly plant-based bitumen waterproof membrane and its preparation method. This method, through a specific modification process, solves problems such as the easy aging of plant-based bitumen at high temperatures and its poor compatibility with petroleum bitumen, producing a high-performance environmentally friendly plant-based bitumen waterproof membrane. This achieves a high proportion of plant-based bitumen substitution in waterproof membranes, reduces production costs, and also has significant environmental benefits.

[0011] To achieve the above objectives, the present invention provides the following technical solution: an environmentally friendly plant-based bitumen waterproof membrane, comprising blended modified bitumen, wherein the blended modified bitumen is composed of the following components by mass percentage: Plant-based bitumen: 40%–50%; Petroleum asphalt: 20%–25%; SBS: 3%~8%; SBR: 2%~5%; Modifier: 1.7%–2.8%; Filler: Balance.

[0012] Furthermore, the plant-based asphalt is at least one or more of cottonseed oil asphalt, rapeseed oil asphalt, or soybean oil asphalt.

[0013] Furthermore, the modifier includes a silane coupling agent and a softener. The silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane, added at a rate of 0.5% to 0.8% of the total mass of the blended modified asphalt. The softener is FX2030, added at a rate of 1.2% to 2% of the total mass of the blended modified asphalt. The γ-(2,3-epoxypropoxy)propyltrimethoxysilane used is product model WD-21, sold by Wuhan Lvke Wenhe Technology Co., Ltd. The FX2030 is purchased from Shandong Furunda Chemical Co., Ltd.

[0014] Furthermore, the filler is at least one or more of talc, calcium carbonate, or mica powder.

[0015] The present invention also provides a method for preparing the waterproof membrane, comprising the following steps: (1) Pretreatment of plant asphalt: Heat the plant asphalt to 90-110℃, add the modifier, stir evenly, and keep warm for 1-2 hours to obtain the pretreated plant asphalt. (2) Preparation of blended modified asphalt: The pretreated plant asphalt and petroleum asphalt are added to the mixing equipment in proportion and stirred at 140-160℃ for 30-60 minutes to obtain an asphalt mixture; then SBS and SBR are added to the asphalt mixture, the temperature is raised to 160-180℃, and high-speed shearing is performed using a colloid mill for 1-2 hours to obtain blended modified asphalt; (3) Adding filler: Add filler to the blended modified asphalt and continue stirring at 150-170°C for 30-45 minutes to obtain modified asphalt coating; (4) Roll preparation: The modified bitumen coating is evenly applied to the base fabric to obtain an environmentally friendly plant bitumen waterproof roll. Of course, the preparation method also includes steps of the prior art, such as evenly applying the modified bitumen coating to the base fabric, cooling and rolling it up to obtain an environmentally friendly plant bitumen waterproof roll. Since these steps are consistent with the prior art, they will not be described in detail.

[0016] Furthermore, the rotational speed of the high-speed shearing in step (2) is 3000 to 6000 rpm.

[0017] The beneficial effects achieved by adopting the above technical solution are as follows: 1. Significant environmental benefits: This invention uses plant-based asphalt to replace 40%–60% of petroleum asphalt, significantly reducing dependence on non-renewable petroleum resources. Plant-based asphalt originates from by-products of vegetable oil processing or waste edible oil, and is a renewable biomass resource. Its carbon emissions throughout its entire life cycle are significantly lower than those of petroleum asphalt. Calculations show that the carbon footprint of the waterproof membrane of this invention is reduced by more than 30% compared to traditional petroleum asphalt membranes.

[0018] Furthermore, the VOC emissions during the preparation process of this invention are low, which can meet the limit requirements of the "Emission Standard of Pollutants for Building Waterproofing Membrane Industry" (GB 36287-2025) and comply with the environmental protection requirements for carbon footprint accounting of building materials in the "Evaluation Standard for Green Buildings" (GB / T 50378-2019) issued by the Ministry of Housing and Urban-Rural Development. It has good environmental benefits and prospects for promotion and application.

[0019] 2. Significantly Improved Compatibility, Achieving High-Proportion Replacement of Plant-Based Bituminous Asphalt: This invention pretreats plant-based bituminous asphalt by introducing specific modifiers (silane coupling agent + softener), effectively reducing the interfacial tension between plant-based bituminous asphalt and petroleum bituminous asphalt, and significantly improving their compatibility. Simultaneously, the synergistic modification of SBS and SBR further enhances the interaction between the components of the modified system, increasing the replacement ratio of plant-based bituminous asphalt from the existing 5%–15% to 40%–60%, breaking through the key bottleneck restricting the large-scale application of plant-based bituminous asphalt in waterproof membranes.

[0020] 3. Excellent Mechanical and Durability Properties: This invention, through the synergistic modification of SBS and SBR dual elastomers and moderate cross-linking, produces a waterproof membrane with excellent comprehensive performance. Testing shows that its maximum tensile strength reaches 980 N / 50 mm, elongation at break reaches 45%, peel strength reaches 90 N / 50 mm, low-temperature flexibility reaches -20℃ without cracking, heat resistance reaches 90℃ without flowing, and accelerated aging life reaches 2500 hours. Compared with the original formula (20%–30% plant bitumen, 50%–60% petroleum bitumen, 2%–5% engine oil, 5%–9% SBS, 3%–6% SBR, 8%–15% filler), the maximum tensile strength is increased by 15%, elongation at break by 11.2%, peel strength by 15%, low-temperature flexibility by 5℃, heat resistance by 5℃, and accelerated aging life by 25%. All performance indicators meet and in some aspects exceed the requirements of relevant national standards.

[0021] 4. Significantly Improved Microstructure and Uniform Modifier Dispersion: In existing technologies, due to the poor swelling effect of plant-based asphalt on SBS, the modifier is difficult to disperse uniformly in the asphalt system, easily resulting in large molecular rubber agglomerates with a diameter of up to 50 μm, which greatly reduces the modification effect. This invention, through a specific pretreatment process and high-speed shear blending with a colloid mill, combined with the compatibilizing effect of coupling agents and the regulating effect of softeners, enables the modifier to disperse uniformly in the asphalt system. The diameter of the rubber particles is reduced from 50 μm before optimization to 5 μm, significantly improving the dispersion uniformity. This improvement in microstructure provides a structural foundation for enhancing the various macroscopic properties of the roll material.

[0022] 5. Significant cost advantage, simple process, and easy to industrialize: Plant-based bitumen is widely available and relatively inexpensive, and its high-proportion substitution for petroleum bitumen can effectively reduce raw material costs. Compared with the original formulation, raw material costs are reduced by approximately 5%. Furthermore, the preparation method of this invention does not require complex equipment or energy-intensive processes; the process flow is simple, and the operating conditions are mild (pretreatment temperature 90–110℃, blending temperature 160–180℃), making it easy to achieve continuous industrial production and demonstrating good economic benefits and market competitiveness.

[0023] 6. Convenient construction and excellent adhesion performance: The waterproof membrane prepared by this invention has excellent adhesion performance and a peel strength of up to 90N / 50mm. It is suitable for self-adhesive construction. No hot melting or adhesive application is required during construction, which can improve construction efficiency, reduce construction costs, and has good construction convenience. Attached Figure Description

[0024] Figure 1 This is a microstructure diagram of the modified bitumen mixed in the waterproof membrane of Example 2 of the present invention (magnification: 10×40).

[0025] Figure 2 Microstructure of modified bitumen mixed with waterproof membrane in Comparative Example 1 (magnification: 10×40). Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments are described clearly and completely below. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Unless otherwise described, the present invention employs existing technologies.

[0027] Example 1: The present invention provides an environmentally friendly plant-based bitumen waterproof membrane, comprising blended modified bitumen, wherein the blended modified bitumen is composed of the following components by mass percentage: Vegetable bitumen: 40%; Petroleum asphalt: 20%; SBS: 8%; SBR: 5%; Modifier: 1.7%; Filler: Balance.

[0028] The plant-based asphalt is cottonseed oil asphalt. The modifier includes 0.5% by mass of a silane coupling agent and 1.2% by mass of a softener. The silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane, the softener is FX2030, and the filler is talc.

[0029] The method for preparing the waterproof membrane includes the following steps: (1) Pretreatment of plant asphalt: Heat the plant asphalt to 90°C, add the modifier, stir evenly, keep warm for 1 hour to obtain the pretreated plant asphalt. (2) Preparation of blended modified asphalt: The pretreated plant asphalt and petroleum asphalt were added to the mixing equipment in proportion and stirred at 140°C for 30 minutes to obtain an asphalt mixture; then SBS and SBR were added to the asphalt mixture, the temperature was raised to 160°C, and high-speed shearing was performed using a colloid mill for 1 hour at a speed of 3000 rpm to obtain blended modified asphalt; (3) Adding filler: Add filler to the blended modified asphalt and continue stirring at 150°C for 30 minutes to obtain modified asphalt coating; (4) Roll preparation: The modified bitumen coating is evenly applied to the base fabric, and then environmentally friendly plant bitumen waterproof roll is obtained by using existing technologies such as cooling and winding. The base fabric used can be any of the existing technologies, such as polyester base fabric or fiberglass base fabric.

[0030] According to existing technical methods, the maximum tensile strength of this waterproof membrane is 940N / 50mm, the elongation at break is 42%, the low-temperature flexibility is no cracking at -20℃, the peel strength is 95N / 50mm, the heat resistance is no flow at 90℃, and the artificial accelerated aging life is 2500h. All performance indicators meet the requirements of GB 18242 standard.

[0031] Brief introduction to the testing method: I. Tensile Strength and Elongation Test Procedures 1. Clamp the sample vertically in the tensile testing machine fixture. The fixture spacing is 200mm, and the extensometer spacing is 180mm. 2. Set the stretching speed: 100 mm / min for asphalt rolls; 3. Start the testing machine and record the maximum tensile force (N) and elongation at break (%). If the sample slips or breaks within 5mm of the edge of the fixture during the test, the sample is invalid and a new sample must be taken.

[0032] 4. Result Calculation Tensile force value: the average value of 5 samples, in N. Elongation at break: (gauge length at break - initial gauge length) / initial gauge length × 100%.

[0033] II. Low-temperature flexibility Testing basis and scope of application: GB / T 328.14-2007 "Test methods for building waterproof membranes - Part 14: Low temperature flexibility of bituminous waterproof membranes" Equipment and material preparation.

[0034] 1. Test equipment Low temperature test chamber: Temperature control range -40℃~30℃, accuracy ±1℃. Low temperature flexibility tester: Equipped with bending shafts of different diameters (commonly Φ20mm, Φ25mm, Φ30mm). Cooling fluid: Ethanol / water solution (volume ratio 2:1, suitable for temperatures above -20℃) or ethylene glycol / water solution (volume ratio 1:1, suitable for temperatures below -20℃). Measuring instruments: Vernier calipers with an accuracy of 0.1mm.

[0035] 2. Sample preparation Size: 150mm×25mm, 5 samples each in the longitudinal and transverse directions. Requirements: The sample surface is free of defects and damage, and the edges are straight. Pretreatment: Place in an environment of 23℃±2℃ and relative humidity of 50%±10% for at least 24 hours.

[0036] 3. Experimental Procedure During equipment debugging, inject the refrigerant into the test tank of the low-temperature flexibility tester, ensuring the liquid level is not less than 100mm. Set the temperature of the low-temperature test chamber to the specified test temperature of -20℃ (depending on the product standard). Adjust the distance between the bending shaft and the bracket: bending shaft diameter + 2mm + 2×sample thickness.

[0037] For cryogenic treatment, place the sample flat on the rack, ensuring that the top of the sample is 10 mm below the surface of the freezing liquid, and place it in the cryogenic test chamber. Keep it at the specified temperature for no less than 2 hours.

[0038] After the bending test reaches the specified time, start the low-temperature flexibility tester and bend the bending shaft upward at a speed of 360 mm / min. Stop when the bending angle reaches 180° and hold for 5 seconds to observe the condition of the sample. Low-temperature protective gloves must be worn during the test to avoid frostbite.

[0039] The results are determined by taking out the sample and observing the surface for cracks under natural light. If four or more of the five samples are free of cracks, they are considered qualified. If the sample cracks within 5mm of the edge of the fixture, the sample is invalid and needs to be resampled and tested.

[0040] III. Heat Resistance Standard Basis and Scope of Application: GB / T328.11-2007 "Test Methods for Waterproofing Membranes - Part 11: Heat Resistance of Bituminous Waterproofing Membranes".

[0041] 1. Test preparation (1) Sample preparation Cutting size: 100mm×50mm rectangular sample, a total of 3 samples were prepared. Sampling requirements: cut from the flat part of the roll material, avoiding edges and defective areas. Pretreatment: place in an environment of 23℃±2℃ and relative humidity of 50%±10% for at least 24 hours.

[0042] (2) Equipment requirements Electric heating constant temperature oven: temperature control range from room temperature to 200℃, accuracy ±1℃. Sample suspension device: composed of metal bracket, hook and heat-resistant clamp. Temperature measuring device: thermocouple with accuracy of 0.1℃, placed near the sample.

[0043] (3) Experimental procedures During equipment debugging, preheat the oven to 92℃ (the test temperature is 2℃ higher than the standard requirement), adjust the suspension device to ensure that the sample spacing is ≥20mm and does not contact the inner wall of the oven.

[0044] The sample is suspended 10mm from one end of the sample and a hole is punched. The sample is then vertically suspended in the oven with a hook and a 100g weight is suspended from the bottom (keeping the roll material hanging naturally).

[0045] Close the oven door after high-temperature treatment and start timing. Maintain the oven temperature at 92℃ for 2 hours. Check the oven temperature every 30 minutes during the test to ensure stability.

[0046] After the observation period, the sample was removed while wearing heat-resistant gloves and observed under natural light to check for the relative displacement between the coating layer and the body, and whether there was any flow or dripping.

[0047] 2. Result Determination (4) Qualification Standard The coating layer should slide no more than 2 mm relative to the body without any dripping or running. At least two out of three samples should meet the requirements, and the overall sample should be deemed qualified.

[0048] IV. Peel Strength Test 1. Standard Basis and Acceptance Threshold: GB / T328.20-2007 "Test Methods for Waterproofing Membranes - Part 20: Peel Performance of Bitumen Waterproofing Membranes".

[0049] 2. Testing Preparation (1) Sample preparation Five 50mm×200mm roll material samples were cut and joints were prepared according to the actual construction process (hot melt method / cold bonding method). The bonding length was 100mm. After treatment, the samples were placed in an environment of 23℃±2℃ and 50%±10% relative humidity for 24 hours.

[0050] (2) Equipment requirements Electronic tensile testing machine: range 0-2000N, accuracy ±1%, tensile speed 100mm / min. Special fixture: width not less than the sample width, with rubber pads on the clamping surface to prevent slippage. Pressure roller: 2kg weight, used to remove air bubbles after bonding.

[0051] (3) Experimental procedures The specimen is fixed by clamping the non-bonded ends of the specimen in the upper and lower clamps of the tensile testing machine with a clamp spacing of 100mm to ensure that the specimen is completely perpendicular to the direction of tensile force and is free from twisting or skewing.

[0052] The tensile test was conducted by uniformly stretching at a speed of 100 mm / min, and the tensile force value was continuously recorded until the joint was completely separated. The force value change curve of the entire process was recorded.

[0053] The peel strength (N / mm) was calculated as follows: average tensile force (N) ÷ specimen width (mm). The arithmetic mean of 5 specimens was taken as the final result and rounded to two decimal places.

[0054] V. Artificial Accelerated Aging Test Method Xenon arc lamp aging test: Test conditions: Irradiance 550W / m² (300-400nm), temperature 60℃±3℃, relative humidity 50%±5%, rainfall cycle 18min / 102min, duration set according to standard (1500 hours).

[0055] Sample preparation: Same as the specifications of the hot air aging sample.

[0056] Performance testing: After aging, tensile properties, low-temperature flexibility, peel strength and other indicators are tested, and appearance changes are observed.

[0057] Example 2: The present invention provides an environmentally friendly plant-based bitumen waterproof membrane, comprising blended modified bitumen, wherein the blended modified bitumen is composed of the following components by mass percentage: Vegetable bitumen: 60%; Petroleum asphalt: 30%; SBS: 3%; SBR: 2%; Modifier: 2.8%; Filler: Balance.

[0058] The plant-based asphalt is rapeseed oil asphalt. The modifier includes 0.8% by mass of a silane coupling agent and 2% by mass of a softener. The silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane, the softener is FX2030, and the filler is calcium carbonate.

[0059] The method for preparing the waterproof membrane includes the following steps: (1) Pretreatment of plant asphalt: Heat the plant asphalt to 110°C, add the modifier, stir evenly, and keep warm for 2 hours to obtain the pretreated plant asphalt. (2) Preparation of blended modified asphalt: The pretreated plant asphalt and petroleum asphalt were added to the mixing equipment in proportion and stirred at 160°C for 60 minutes to obtain an asphalt mixture; then SBS and SBR were added to the asphalt mixture, the temperature was raised to 180°C, and high-speed shearing was performed using a colloid mill for 2 hours at a speed of 6000 rpm to obtain blended modified asphalt. (3) Adding filler: Add filler to the blended modified asphalt and continue stirring at 170°C for 45 minutes to obtain modified asphalt coating; (4) Roll preparation: The modified bitumen coating is evenly applied to the base fabric, and then environmentally friendly plant bitumen waterproof roll is obtained by using existing technologies such as cooling and winding. The base fabric used can be any of the existing technologies, such as polyester base fabric or fiberglass base fabric.

[0060] Using the method described in Example 1, the waterproof membrane exhibited a maximum tensile strength of 980 N / 50 mm, an elongation at break of 43%, low-temperature flexibility (no cracking at -20℃), a peel strength of 88 N / 50 mm, heat resistance (no flow at 90℃), and an accelerated aging life of 2500 hours. All performance indicators met the relevant standard requirements. The microstructure of the modified bitumen in the waterproof membrane obtained in this example is shown in the image. Figure 1 As can be seen, the rubber particles have a diameter of 5μm and good dispersion uniformity.

[0061] Example 3: The present invention provides an environmentally friendly plant-based bitumen waterproof membrane, comprising blended modified bitumen, wherein the blended modified bitumen is composed of the following components by mass percentage: Plant-based bitumen: 50%; Petroleum asphalt: 25%; SBS: 5%; SBR: 3%; Modifier: 2.1%; Filler: Balance.

[0062] The plant-based asphalt is soybean oil asphalt, the modifier includes 0.6% by mass of silane coupling agent and 1.5% by mass of softener, the silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane, the softener is FX2030, and the filler is mica powder.

[0063] The method for preparing the waterproof membrane includes the following steps: (1) Pretreatment of plant asphalt: Heat the plant asphalt to 100°C, add the modifier, stir evenly, and keep warm for 1.5 hours to obtain the pretreated plant asphalt. (2) Preparation of blended modified asphalt: The pretreated plant asphalt and petroleum asphalt were added to the mixing equipment in proportion and stirred at 150°C for 45 minutes to obtain an asphalt mixture; then SBS and SBR were added to the asphalt mixture, the temperature was raised to 170°C, and high-speed shearing was performed using a colloid mill for 1.5 hours at a speed of 4500 rpm to obtain blended modified asphalt; (3) Adding filler: Add filler to the blended modified asphalt and continue stirring at 160°C for 40 minutes to obtain modified asphalt coating; (4) Roll preparation: The modified bitumen coating is evenly applied to the base fabric, and then environmentally friendly plant bitumen waterproof roll is obtained by using existing technologies such as cooling and winding. The base fabric used can be any of the existing technologies, such as polyester base fabric or fiberglass base fabric.

[0064] Using the method in Example 1, the waterproof membrane exhibits a maximum tensile strength of 960 N / 50 mm, an elongation at break of 42%, low-temperature flexibility with no cracks at -20℃, a peel strength of 90 N / 50 mm, heat resistance without flow at 90℃, and an accelerated aging life of 2500 h. All performance indicators meet the relevant standard requirements.

[0065] The following is a partial list of the research and development process to illustrate the beneficial effects achieved by the present invention. It should be noted that the method for testing performance is the method listed in Example 1. Unless otherwise specified, all methods are existing technologies.

[0066] Comparative Example 1 (lacking modifier) Formula: 60% plant asphalt, 30% petroleum asphalt, 3% SBS, 2% SBR, filler balance (no modifier added), the formula is generally the same as in Example 2.

[0067] Preparation method: Same as in Example 2, but omit the pretreatment of plant asphalt in step (1) (i.e., do not add modifier), and directly mix plant asphalt with petroleum asphalt and then add SBS and SBR for blending.

[0068] Due to the lack of compatibilizing effect of coupling agents and regulating effect of softeners, plant asphalt and petroleum asphalt have high interfacial tension and poor compatibility. SBS exhibits poor swelling properties in plant-based bitumen, making it difficult to uniformly disperse modifiers and resulting in the formation of large molecular rubber aggregates (aggregate diameter > 50 μm). Figure 2 As shown; The maximum tensile strength is 750-800N / 50mm, the elongation at break is about 30%-35%, and the low-temperature flexibility is only about -15℃.

[0069] Comparative Example 2 (coupling agent only, no softener added) Formula: 60% plant asphalt, 30% petroleum asphalt, 3% SBS, 2% SBR, 1% silane coupling agent WD-21, filler balance (without adding softener FX2030), the formula is generally the same as in Example 2.

[0070] Preparation method: Same as in Example 2.

[0071] Coupling agents can improve the interfacial compatibility between plant asphalt and petroleum asphalt, but they lack the plasticizing and regulating effects of softeners. The modulus of the modified system does not match that of the plant-based bitumen matrix, resulting in stress concentration and limited improvement in mechanical properties. Maximum tensile strength is approximately 850-880 N / 50 mm, elongation at break is approximately 36%-38%, and low-temperature flexibility is approximately -20℃.

[0072] Comparative Example 3 (only softener added, no coupling agent added) Formula: 60% plant asphalt, 30% petroleum asphalt, 3% SBS, 2% SBR, 1% softener FX2030, filler balance (without silane coupling agent WD-21), the formula is generally the same as in Example 2.

[0073] Preparation method: Same as in Example 2.

[0074] Softeners can improve the flexibility and processing fluidity of plant-based asphalt, but they cannot solve the interfacial compatibility problem between plant-based asphalt and petroleum asphalt. There is a lack of chemical bonding between the polar groups of SBS / SBR and plant bitumen, and the physical entanglement network is unstable. Maximum tensile strength is approximately 820-850 N / 50 mm, elongation at break is approximately 35%-38%, and heat resistance is approximately 80℃.

[0075] Comparative Example 4 (SBS and SBR have the same total addition amount, but only SBS is used) Formula: 60% plant asphalt, 30% petroleum asphalt, 5% SBS, 1% modifier, filler balance (no SBR added, replaced by an equal amount of SBS). The formula is generally the same as in Example 2.

[0076] Preparation method: Same as in Example 2.

[0077] Although SBS can build an elastic network and improve its resistance to deformation at high temperatures, SBS has poor compatibility with polar components in plant bitumen (such as lignin derivatives). The lack of SBR in the short-branched network fills the gaps and forms hydrogen bonds with the polar groups of plant pitch, resulting in uneven intermolecular forces in the modified system. It has insufficient low-temperature crack resistance and self-healing ability, and its low-temperature flexibility is only about -20℃. The maximum tensile strength is approximately 880-900 N / 50 mm, and the elongation at break is approximately 38%-40%.

[0078] Comparative Example 5 (SBS and SBR were added in the same total amount, but only SBR was used) Formula: 60% plant asphalt, 30% petroleum asphalt, 5% SBR, 1% modifier, filler balance (no SBS added, replaced by an equal amount of SBR), the formula is generally the same as in Example 2.

[0079] Preparation method: Same as in Example 2.

[0080] Although SBR has good compatibility with the polar components of plant bitumen and excellent elastic recovery, it lacks the rigidity and strength provided by the styrene in the hard segment of SBS. It is impossible to construct a main elastic network, resulting in insufficient high-temperature deformation resistance and fatigue resistance. It has a heat resistance of only about 80℃ without flowing, and is easily deformed at high temperatures.

[0081] Comparative Example 6 (plant bituminous ... Formula: 70% plant asphalt, 10% petroleum asphalt, 3% SBS, 2% SBR, 3% modifier, filler balance. The formula is largely the same as in Example 2. Preparation method: Same as in Example 2.

[0082] The proportion of plant asphalt is too high and the proportion of petroleum asphalt is too low. Although modifiers are used to improve compatibility, the inherent defects of plant asphalt, such as easy aging at high temperatures and easy cracking at low temperatures, cannot be completely compensated. Mechanical properties and weather resistance are significantly reduced, with a maximum tensile force of <800N / 50mm, low-temperature flexibility of only about -15℃, and artificial accelerated aging life of <1500h.

[0083] Comparative Example 7 (unblended by high-speed shear blending without colloid mill) Formula: Same as Example 2.

[0084] Preparation method: The high-speed shearing and blending step of colloid milling is omitted. Instead, ordinary stirring (approximately 200-500 rpm) is used to blend the mixture at 160-180℃ for 2 hours.

[0085] SBS and SBR cannot be sufficiently dispersed, and SBS has a poor swelling effect in plant-based bitumen. The presence of large molecular rubber aggregates (aggregate diameter > 50 μm) significantly reduces the modification effect; The maximum tensile strength is approximately 800-850 N / 50 mm, and the elongation at break is approximately 32%-35%.

[0086] Comparative Example 8 (direct blending without pretreatment of plant bitumen) Formula: Same as Example 2.

[0087] Preparation method: Skip the pretreatment of plant asphalt in step (1) (that is, heat the plant asphalt to 90-110℃, add the modifier and keep it warm for 1-2 hours), and directly add the plant asphalt, petroleum asphalt, SBS, SBR and modifier into the mixing equipment, and shear and blend them at high speed in a colloid mill at 160-180℃.

[0088] Modifiers (especially coupling agents) failed to react fully with plant pitch at low temperatures, resulting in poor coupling effects; The polar groups in plant-based bitumen are not fully activated and do not bind sufficiently with the hydrogen bonds of SBR. The rubber particles exhibit poor dispersion uniformity, with aggregates having a diameter of approximately 20-30 μm. The maximum tensile strength is approximately 880-900 N / 50 mm, and the elongation at break is approximately 38%-40%.

[0089] Meanwhile, the carbon footprint of the waterproof membrane invented in this invention is reduced by more than 30% compared to traditional petroleum asphalt membranes. The specific calculation process is as follows: I. Calculation Method Carbon footprint (CF) = Total emissions at each stage of the life cycle = Σ (Activity Qi × Emission factor EFi) Where: Qi: Activity data at each stage (e.g., raw material usage, energy consumption, transportation distance, etc.) EFi: Greenhouse gas emission factor per unit of activity (e.g., kgCO2e / kg raw materials, kgCO2e / kWh electricity).

[0090] II. Calculation Steps in Stages Carbon emissions from petroleum asphalt during raw material acquisition: Emissions = Petroleum asphalt usage × Petroleum asphalt emission factor. Source of emission factor: IPCC database, "Guidelines for Carbon Emission Accounting in China's Petrochemical Industry" (approximately 2.85 tCO2e / t petroleum asphalt). Carbon emissions from plant asphalt: Emissions = Plant asphalt usage × Plant asphalt emission factor. Explanation of emission factor: Emissions from plant asphalt need to be calculated during the raw material collection and processing process, and are typically 0.3-0.8 tCO2e / t plant asphalt (far lower than petroleum asphalt).

[0091] Carbon emissions from energy consumption during the manufacturing stage: Emissions = (Electricity consumption × Electricity emission factor) + (Fuel consumption × Fuel emission factor) Sources of emission factors: Local power grid emission factor (e.g., approximately 0.6 tCO2e / MWh in Northeast China), "Guidelines for the Compilation of Provincial Greenhouse Gas Inventories" Carbon emissions from the process: Emissions = Emissions from fossil fuel combustion during asphalt heating / modification Note: Substituting plant-based asphalt may lower the process temperature and reduce this part of the emissions. Emissions during transport = Transport distance × Emission factor of transport vehicle × Emission factor of cargo weight. Reference: Diesel trucks are approximately 0.28 kgCO2e / ton·km, and gasoline trucks are approximately 0.24 kgCO2e / ton·km.

[0092] During the service phase, the carbon emissions of waterproof membranes are typically low, negligible or only related to the energy consumption during installation and construction.

[0093] Emissions during waste disposal = Amount of waste × Emission factor for landfill / incineration. Advantages of plant-based bitumen: It is biodegradable, and methane emissions during landfill are far lower than those of petroleum bitumen.

[0094] III. Calculation of Substitution Ratio and Emission Reduction The carbon footprint (CF0) of traditional petroleum asphalt roofing membranes: CF0 = Raw material emissions + Production emissions + Transportation emissions + Waste emissions. Carbon footprint (CF1) after plant-based bitumen substitution: CF1 = (Petroleum bitumen usage × (1 - substitution ratio) × Petroleum bitumen emission factor) + (Plant-based bitumen usage × substitution ratio × Plant-based bitumen emission factor) + Production emissions (adjusted) + Transportation emissions + Waste emissions. Carbon emission reduction rate = (CF0 – CF1) / CF0 × 100% Case reference: Based on an average substitution ratio of 50%, the emission reduction rate can reach 30%-40%.

[0095] Furthermore, the technical solution of this invention has low VOC emissions during the preparation process, which can meet the limit requirements of the "Emission Standard of Pollutants for Synthetic Resin Industry" (GB 31572-2015) and comply with the environmental protection requirements for carbon footprint accounting of building materials in the "Evaluation Standard for Green Buildings" (GB / T 50378-2019) issued by the Ministry of Housing and Urban-Rural Development.

[0096] Brief introduction to the detection method: Currently, the industry adopts a common testing and accounting system for VOCs in waterproof membranes. The VOCs content of the products is determined according to GB / T23986.2-2023 "Determination of Volatile Organic Compounds (VOCs) Content in Paints and Varnishes Part 2: Gas Chromatography" and GB / T 41078-2021 "Test Methods for Hazardous Substances in Building Waterproofing Materials". The gas chromatography-mass spectrometry (GC-MS) combined with thermal desorption method is used to qualitatively and quantitatively detect the finished product samples, and to determine the total VOCs content and the amount of volatiles per unit area. VOCs emissions from the production process are regulated according to GB 31572-2015 "Emission Standard of Pollutants for Synthetic Resin Industry". Organized and unorganized waste gas from processes such as stirring, shearing, and coating are sampled and tested at fixed points, and data correction is completed in combination with operating conditions.

[0097] The industry generally uses a method combining pollution generation coefficients with on-site measurement corrections to calculate VOC emissions. Based on the basic pollution generation coefficients in the "Second Handbook of Industrial Source Pollution Generation and Discharge Coefficients," the theoretical generation is calculated using production capacity and working hours. This is then corrected using waste gas concentration, collection efficiency, and treatment removal efficiency to finally obtain the VOC emissions per unit product (g / m³). 2 ) and VOCs emission concentration in exhaust gas (mg / m³) 3 Key indicators. Traditional petroleum asphalt waterproof membranes generally use solvent-based additive blending processes, adding large amounts of volatile solvents and highly volatile additives during production. Under high-temperature processing conditions, VOCs emissions are high, with conventional products emitting 15–50 g / m² of VOCs per unit area. 2 The concentration of VOCs in the production waste gas is 20-45 mg / m³. 3 Only some of the optimized processes can meet the old national standards, making it difficult to adapt to the stringent emission control requirements of the current standards.

[0098] II. VOCs situation of the technical solution of the present invention: 2.1 Core Technology Principle of Low VOCs in this Invention This invention employs a solvent-free hot-melt blending process, without adding any volatile organic solvents such as benzene or esters. The core raw materials are plant-based asphalt, petroleum asphalt, SBS / SBR modifiers, and inorganic fillers, along with a dedicated low-VOC modification system. The silane coupling agent and FX2030 softener are added in low amounts and exhibit strong thermal stability, with no significant release of volatile organic compounds within the processing temperature range of 90–180°C. This eliminates the generation of large amounts of VOCs from both the raw material formulation and the production process, giving it a natural environmental advantage compared to traditional solvent-modified asphalt roofing sheets.

[0099] 2.2 VOCs detection and calculation results of this invention Using the industry-standard GC-MS testing method and the actual pollution coefficient correction method, the entire process of testing and calculation of the environmentally friendly plant-based bitumen waterproof membrane and its preparation process of this invention was carried out. The core data are as follows: VOC emissions per unit product: The VOC emissions per unit area of ​​the product of this invention are only 2.2 to 3.8 g / m². 2 It is far superior to traditional roll materials (15-50 g / m²). 2 This is within the industry's standard range. According to the "Emission Standard of Pollutants for Synthetic Resin Industry" (GB 31572-2015, including the 2024 amendment), the non-methane total hydrocarbon emissions of this product meet the standard's requirements for calculating emissions per unit product.

[0100] VOCs emission concentration in production waste gas: The measured concentrations of VOCs in both organized and unorganized waste gas from various production processes ranged from 8 to 15 mg / m³. 3 It meets the requirements of the conventional emission limits (non-methane total hydrocarbons ≤ 100 mg / m³) and special emission limits (non-methane total hydrocarbons ≤ 60 mg / m³) in the "Emission Standard of Pollutants for Synthetic Resin Industry" (GB 31572-2015, including the 2024 amendment), and also meets the control requirements of the hourly average concentration of non-methane total hydrocarbons in fugitive emissions at the plant boundary being ≤ 4.0 mg / m³.

[0101] The inherent VOCs content of the product: The VOCs content of the finished roll material is ≤12g / kg, which falls into the category of low-volatile environmentally friendly building materials, and there is no problem of continuous large-scale release of VOCs during later use.

[0102] 2.3 Summary of Standard Compliance and Environmental Advantages Testing and calculations show that the VOCs generation and emissions of this invention are extremely low throughout the entire process, and all indicators fully meet the latest limit requirements of the "Emission Standard of Pollutants for Synthetic Resin Industry" (GB 31572-2015, including the 2024 amendment). Furthermore, the low VOCs and low emissions production characteristics significantly reduce the carbon footprint of the product throughout its entire life cycle, fully complying with the core requirements of carbon footprint accounting for building materials and the access standards for green and environmentally friendly building materials in the Ministry of Housing and Urban-Rural Development's "Evaluation Standard for Green Buildings" (GB / T 50378-2019).

[0103] As can be seen from the above, this invention uses plant-based asphalt to largely replace petroleum asphalt, which not only reduces costs but also leverages the synergistic effects of the molecular structures of SBS and SBR, the interfacial compatibilizing effect of the modifier, and the three-dimensional network structure formed by moderate cross-linking. SBS is a styrene-butadiene-styrene block copolymer, in which the hard styrene segment provides rigidity and strength, while the soft butadiene segment imparts elasticity and low-temperature toughness. Its linear molecular structure facilitates the formation of a physically entangled network in asphalt. SBR is styrene-butadiene rubber, in which the random copolymerized styrene and butadiene segments have slightly higher polarity than SBS, resulting in better compatibility with the polar components (carboxyl groups, hydroxyl groups, etc.) in plant-based asphalt and excellent elastic recovery. In the plant-based bituminous system, the two components create a triple synergistic effect: Structurally, the linear long chains of SBS construct the main elastic network, while the short branches of SBR fill the gaps in the network and form hydrogen bonds with the polar groups of the plant-based bituminous system, making the intermolecular forces of the modified system more uniform; in terms of performance, SBS enhances the high-temperature resistance to deformation and fatigue, while SBR enhances the low-temperature resistance to cracking and self-healing, and the combination of the two broadens the performance range at both high and low temperatures; in terms of dynamic mechanical equilibrium, under the action of external force, the hard segments of SBS bear the main stress, while the soft chains of SBR disperse the stress through molecular chain slippage, and rebound together after the external force disappears, improving the resistance to permanent deformation. At the same time, the silane coupling agent reduces the interfacial tension by constructing "molecular bridges" between the plant-based bituminous system and petroleum bituminous system, as well as between SBS / SBR, while the softener adjusts the modulus and viscosity of the plant-based bituminous matrix, creating favorable kinetic conditions for chemical bonding. The two synergistically constitute a dual compatibilization mechanism of "chemical bonding + physical matching". Based on physical entanglement, moderate crosslinking connects different polymer segments through covalent bonds to form a three-dimensional chemical crosslinking network. This enhances structural stability and prevents modifier precipitation or performance degradation at high temperatures. It also optimizes the modulus matching between the modifier network and the plant-based bitumen matrix, reducing interfacial stress transfer losses. Simultaneously, the crosslinking points effectively disperse cyclic stress, delay molecular chain aging, and control compatibility balance—preserving some segment slippage ability to maintain good compatibility while strengthening interfacial interactions through chemical bonding. The synergistic effect at the molecular level ultimately manifests as a comprehensive improvement in macroscopic performance. The pretreatment step ensures that the coupling agent preferentially reacts with the active groups of the plant-based bitumen, while the high-speed shearing of the colloid mill forcibly disperses the SBS / SBR aggregates to the micron level (reducing them from 50 μm to 5 μm). Both processes jointly guarantee the effective realization of the modification mechanism.

[0104] It should be noted that the above-described technical content of this invention is merely an explanation and clarification to enable those skilled in the art to understand the technical essence of this invention, and therefore is not intended to limit the scope of protection of this invention. The scope of protection of this invention should be determined by the claims. Those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made based on the essential spirit of this invention should be within the scope of protection of this invention.

Claims

1. An environmentally friendly plant-based bitumen waterproof membrane, characterized in that, Includes blended modified asphalt, which, by mass percentage, comprises the following components: Plant-based bitumen: 40%–50%; Petroleum asphalt: 20%–25%; SBS: 3%~8%; SBR: 2%~5%; Modifier: 1.7%–2.8%; the modifier includes a silane coupling agent and a softener, wherein the silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and the addition amount is 0.5%–0.8% of the total mass of the blended modified asphalt; the softener is FX2030, and the addition amount is 1.2%–2% of the total mass of the blended modified asphalt; Filler: Balance.

2. The waterproof membrane according to claim 1, characterized in that, The plant-based asphalt is at least one or more of cottonseed oil asphalt, rapeseed oil asphalt, or soybean oil asphalt.

3. The waterproof membrane according to claim 1, characterized in that, The filler is at least one or more of talc, calcium carbonate, or mica powder.

4. The method for preparing the waterproof membrane according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Pretreatment of plant asphalt: Heat the plant asphalt to 90-110℃, add the modifier, stir evenly, and keep warm for 1-2 hours to obtain the pretreated plant asphalt. (2) Preparation of blended modified asphalt: The pretreated plant asphalt and petroleum asphalt are added to the mixing equipment in proportion and stirred at 140-160℃ for 30-60 minutes to obtain an asphalt mixture; then SBS and SBR are added to the asphalt mixture, the temperature is raised to 160-180℃, and high-speed shearing is performed using a colloid mill for 1-2 hours to obtain blended modified asphalt; (3) Adding filler: Add filler to the blended modified asphalt and continue stirring at 150-170°C for 30-45 minutes to obtain modified asphalt coating; (4) Roll preparation: The modified bitumen coating is evenly applied to the base fabric to obtain an environmentally friendly plant bitumen waterproof roll.

5. The method according to claim 4, characterized in that, The rotational speed of the high-speed shearing in step (2) is 3000 to 6000 rpm.

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