Plant-based asphalt waterproof coiled material and preparation method thereof

Abstract

The invention provides a plant-based asphalt waterproof coiled material and a preparation method and device thereof, and belongs to the technical field of waterproof coiled materials, the preparation method comprises the following steps: firstly, pretreating cottonseed oil asphalt through esterification reaction to reduce the polarity of the cottonseed oil asphalt and improve the compatibility of the cottonseed oil asphalt with petrochemical asphalt; then blending the modified cottonseed oil asphalt with petrochemical asphalt, waste engine oil, SBS (Styrene Butadiene Styrene) and filler, wherein the cottonseed oil asphalt can replace the petrochemical asphalt in a high proportion; the prepared waterproof coiled material has excellent high and low temperature resistance, waterproof performance and weather resistance, meanwhile, resource utilization of waste materials is achieved, the production cost is reduced, and remarkable environmental protection benefits and economic values are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of waterproof rolls, and in particular relates to a plant-based asphalt waterproof roll and a preparation method thereof. Background Art

[0002] The core raw material of asphalt waterproofing membranes, which are widely used in building waterproofing projects, is petrochemical asphalt. However, traditional petrochemical asphalt faces two severe challenges.

[0003] The first is resource dependence and cost pressure. Petrochemical asphalt is highly dependent on non-renewable oil resources. According to energy statistics, the annual growth rate of global proven oil reserves has slowed to 0.8%, while the growth rate of demand for asphalt in the construction waterproofing industry has remained stable at more than 3.5%. The contradiction between supply and demand is becoming increasingly prominent.

[0004] Secondly, petrochemical asphalt production (typically at temperatures between 160-200°C) produces significant amounts of volatile organic compounds (VOCs), including polycyclic aromatic hydrocarbons (PAHs), which are listed in the "Catalogue of Toxic and Hazardous Air Pollutants." The "Industrial Pollutant Emission Standard for Building Waterproofing Membranes" (GB 36287-2025), which will be implemented in 2025, will tighten VOC emission limits, placing significant pressure on existing production processes to undergo environmentally friendly upgrades. Furthermore, the Ministry of Housing and Urban-Rural Development's "Green Building Evaluation Standard" (GB / T 50378-2025) has added requirements for calculating the carbon footprint of building materials, placing restrictions on the use of petrochemical asphalt membranes due to their high carbon emissions.

[0005] Therefore, the development of renewable, low-pollution plant-based asphalt has become a key direction for the industry's green transformation. Plant-based asphalt (such as that produced from byproducts such as cottonseed oil and waste cooking oil) not only reduces reliance on fossil resources but also significantly reduces energy consumption and carbon emissions during the production process. However, the application of plant-based asphalt in waterproofing membranes in existing technologies still faces technical bottlenecks, primarily manifested in low replacement ratios (typically in the 5%-15% range) and poor compatibility between plant-based asphalt and petrochemical asphalt, which affects the overall performance of the final product. Therefore, the development of a plant-based asphalt waterproofing membrane that can replace petrochemical asphalt at a high rate and exhibit excellent performance, as well as its preparation method, is of great practical significance and market value. Summary of the Invention

[0006] In order to overcome the problems in the background technology, the present invention provides a high-proportion plant-based asphalt waterproofing membrane and a preparation method thereof, aiming to solve the problems faced by traditional petrochemical asphalt waterproofing membranes, such as strong resource dependence, high cost, environmental pollution, low replacement rate of existing plant-based asphalt, and poor compatibility.

[0007] To achieve the above object, the present invention is implemented through the following technical solutions: A plant-based asphalt waterproofing membrane is composed of a base fabric and a blended modified asphalt layer coated thereon, wherein the blended modified asphalt layer is made of the following components by mass percentage: Modified cottonseed oil asphalt: 36%; Petrochemical asphalt: 12%; Waste engine oil: 7%; Thermoplastic elastomer powder: 5%; Waste tire rubber powder: 20%; Calcite powder: 20%.

[0008] Furthermore, the modified cottonseed oil asphalt is an esterification product obtained by reacting cottonseed oil asphalt with alcohol in the presence of a catalyst.

[0009] A method for preparing a plant-based asphalt waterproofing membrane comprises the following steps: S1. Pretreatment of cottonseed oil pitch: esterifying the cottonseed oil pitch with an excess of alcohol in the presence of a catalyst to reduce the polarity of the cottonseed oil pitch to obtain modified cottonseed oil pitch; S2. Preparation of a modifier: mixing a thermoplastic elastomer with waste engine oil and swelling the mixture at 180° C. to prepare a modifier; S3, preparation of blended modified asphalt: mixing the modified cottonseed oil asphalt with petrochemical asphalt to obtain an asphalt mixture; adding the modifier prepared in S2 to the asphalt mixture, and then adding waste tire rubber powder and calcite powder in sequence, and blending at 180° C. to obtain a blended modified asphalt; S4. Preparation of the roll material: coating the blended modified asphalt on the base cloth to prepare the plant-based asphalt waterproof roll material.

[0010] Furthermore, the alcohol in S1 is anhydrous ethanol, and the amount of the excess alcohol is 1.4 times the theoretical molar amount of carboxyl groups in cottonseed oil asphalt.

[0011] Furthermore, the catalyst in S1 is sulfonic acid resin, and the amount used is 2% of the mass of cottonseed oil asphalt.

[0012] Furthermore, the temperature of the esterification reaction in S1 is 110-130° C., and the reaction time is 4-6 hours.

[0013] Furthermore, the mass ratio of modified cottonseed oil asphalt to petrochemical asphalt in S1 is 3:1.

[0014] Beneficial effects of the present invention: 1. The present invention successfully increases the replacement rate of cottonseed oil asphalt in asphalt mixtures to 75% by esterification modification, far exceeding the existing level of 5%-15%. At the same time, it innovatively uses waste engine oil to replace traditional aromatic oil as a plasticizer, and uses waste tire rubber powder as a filler, realizing the resource utilization of waste materials, which is in line with the concept of a green circular economy.

[0015] 2. Through esterification modification, the molecular structure of cottonseed oil asphalt is reshaped, forming a more stable network system, effectively improving the material's resistance to high and low temperatures and anti-aging ability; the finished waterproof membrane has excellent performance, heat resistance up to 84°C, low-temperature flexibility up to -29°C, and impermeability for 120 minutes under a pressure of 0.5Mpa. The performance is 1-3 times higher than that of unmodified plant-based asphalt membrane, and fully meets or even exceeds the requirements of the national standard (GB 23441-2007).

[0016] 3. In the preparation process proposed in this invention, both the ethanol modifier and the sulfonic acid resin catalyst are recyclable, reducing production costs and minimizing secondary pollution. Cost accounting of the final product demonstrates a significant price advantage over some existing solutions, laying the foundation for large-scale industrial production. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and beneficial effects of the present invention clearer, the preferred embodiments of the present invention will be described in detail below to facilitate understanding by technicians.

[0018] Example 1 Raw materials and formula The final blended modified asphalt formula used in this embodiment is (by mass): 48% asphalt mixture, 7% waste engine oil, 5% SBS powder, 20% 60-mesh waste tire rubber powder, and 20% 200-mesh calcite powder; among them, the 48% asphalt mixture is composed of 75% modified cottonseed oil asphalt and 25% No. 70 petrochemical asphalt, that is, the modified cottonseed oil asphalt accounts for 36% of the final product and the No. 70 petrochemical asphalt accounts for 12%.

[0019] Preparation process S1: Pretreatment of cottonseed oil asphalt (1) The amount of ethanol used is determined by the acid value of cottonseed oil asphalt. Excessive ethanol esterification reduces the polarity of cottonseed oil asphalt, thereby increasing its compatibility with petrochemical asphalt. The limit ratio of cottonseed oil asphalt is determined by the product: Determination of the acid value of cottonseed oil pitch: The acid value of cottonseed oil pitch varies greatly between batches (influenced by the degree of refining and oxidation). The acid value is determined using the potentiometric titration method (GB / T 264-1983). (2) Infer the carboxyl content through the acid value (AV): Acid value definition: milligrams of potassium hydroxide (KOH) required to neutralize the free acid in 1g of sample (mgKOH / g); Conversion between carboxyl group (-COOH) and acid value: number of moles of carboxyl group = acid value / molar mass of KOH (56.11 g / mol); Carboxyl mass fraction = number of carboxyl moles × molar mass of carboxyl 45 g / mol × 100%; The acid value of the purchased cottonseed oil asphalt is 204 mg (KOH / g); Then: Number of moles of carboxyl groups = 204×10⁻³ g (KOH / g) ÷ 56.11 g / mol ≈ 3.63×10⁻³ mol / g; (3) Determine the amount of anhydrous ethanol: The esterification reaction is a reversible reaction, and excess ethanol pushes the equilibrium toward ester formation. Ethanol will be lost during the reaction (needs to be recovered by reflux condensation). The optimal amount is 40% excess ethanol (molar ratio), that is, the actual amount is 1.4 times the theoretical value. Ethanol can be recovered in industrial production. Calculation of ethanol usage: Calculate the theoretical amount of anhydrous ethanol required for the esterification reaction based on the acid value, and use a 1.4-fold excess to promote the reaction (for example, the theoretical amount of ethanol required in 1 kg of cottonseed oil pitch is ≈ 3.63 mol × 46.07 g / mol ≈ 167 g, that is, the actual amount of ethanol used in 1 kg of cottonseed oil pitch is = 167 g × 1.4 ≈ 234 g); (4) Cottonseed oil pitch pretreatment: 12 parts of cottonseed oil pitch were added to a three-necked flask equipped with a stirrer and a reflux device, heated to 80°C and stirred at 400 r / min, and 2% sulfonic acid resin (Amberlyst-15) was added as a catalyst. The mixture was stirred for 10 minutes to disperse evenly, and then 1.4 times excess anhydrous ethanol was added according to the acid value. The mixture was heated to 130°C and kept under reflux for 4 hours. (5) Post-treatment: After the reaction is completed, the resin and the reaction liquid (ethanol + esterification product) are separated by hot filtration, and the resin is washed with excess ethanol 2 to 3 times for recovery, distilled at 90 °C for 1 h, the excess ethanol is recovered, and distilled at 130 °C for 1 h to remove the moisture in the asphalt matrix to obtain the pretreated modified cottonseed oil asphalt.

[0020] S2: Preparation of modifier Weigh 7 parts of waste oil and 5 parts of SBS powder according to the formula ratio, mix and swell in a reactor at 180°C for 30 minutes to increase the oil absorption and cross-linking degree of SBS; S3: Preparation of blended modified asphalt (1) The modified cottonseed oil asphalt prepared in step S1 is mixed with No. 70 petrochemical asphalt in a mass ratio of 3:1, dispersed evenly, and kept at a constant temperature for later use; (2) adding the waste engine oil / SBS modifier prepared in step S2 to the heated asphalt mixture; (3) Slowly add 20 parts of 60-mesh waste tire rubber powder and stir at a constant temperature of 180°C for 2 hours; (4) Then slowly add 20 parts of 200-mesh calcite powder gradually, avoiding adding too quickly and causing the temperature to drop and become sticky. Keep it for 1 hour before removing from the pan.

[0021] S4. Preparation of coiled material The obtained blended modified asphalt is evenly coated on both sides of 200g polyester base cloth through coating equipment to a thickness of 3mm, and then covered with a PE isolation film with silicone oil. The prepared roll is cured at room temperature for 24 hours and then the performance test can be carried out.

[0022] In order to verify the modified effect of cottonseed oil asphalt and determine the amount of cottonseed oil asphalt added, the above process was used for production, and only the formula was different and a comparative example was set, as follows: Table 1 Experimental formula Comparative Example 1: Same as Example 1, except that 36% of unmodified cottonseed oil asphalt was used.

[0023] Comparative Example 2-4: Same as Example 1, except that the replacement ratio of modified cottonseed oil asphalt is gradually increased (from 0% to 25% and then to 50%).

[0024] Comparative Example 5: Same as Example 1, except that 100% modified cottonseed oil asphalt was used.

[0025] Comparative Examples 6-8: Same as Example 1, except that Examples 6 and 8 used direct mixing instead of step-by-step mixing, i.e., waste engine oil, SBS powder, waste tire rubber powder, and calcite powder were directly added after the S1 post-treatment was completed; Examples 6 and 7 used aromatic oil instead of waste engine oil for testing.

[0026] Comparative experiment To verify the technical effects of the present invention, key indicators such as heat resistance, low-temperature flexibility, water impermeability, peel strength, oil permeability, and thermal aging performance of Example 1 and Comparative Examples 1-8 were tested in accordance with GB 23441-2007 "Self-adhesive polymer modified asphalt waterproof membrane". The test results according to the standard are as follows: Table 2 Experimental data table Performance Analysis Comparative Example 1: Using 36% of unmodified cottonseed oil asphalt, its heat resistance is only 51°C, far lower than the national standard requirement of 70°C, indicating that unmodified cottonseed oil asphalt cannot be used in high proportions.

[0027] Comparative Examples 2-4: The replacement ratio of modified cottonseed oil asphalt was gradually increased (from 25% to 50% and then to 75%), and the performance met the national standards. However, the comprehensive performance and cost control of Example 1 (replacement rate of 75%) achieved the best balance.

[0028] Comparative Example 5: When 100% modified cottonseed oil asphalt was used, its heat resistance (64°C) and peel strength decreased, indicating that the performance was unstable after completely replacing petrochemical asphalt and needed to be compounded with a certain proportion of petrochemical asphalt.

[0029] Comparative Examples 6-8: Comparative Example 8 (direct mixing) and Example 1 (step-by-step mixing) demonstrate that the step-by-step modification method significantly improves the heat resistance and peel strength of SBS, demonstrating the superiority of this process. Comparative Example 7 (using aromatic oil) and Example 1 (using waste engine oil) demonstrate that using waste engine oil is not only more environmentally friendly, but also produces coils with comparable performance to those using aromatic oil, and even surpasses them in some indicators.

[0030] In summary, the technical solution provided by the present invention, through esterification pretreatment of cottonseed oil asphalt and the adoption of an optimized step-by-step modification process, successfully achieved the preparation of waterproof membranes with performance that fully meets or even exceeds national standards when a high proportion of plant-based asphalt is added (replacement rate reaches 75%), which has significant technological progress and practical value.

[0031] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A plant-based asphalt waterproofing membrane, characterized in that: It consists of a tire base cloth and a blended modified asphalt layer coated thereon, wherein the blended modified asphalt layer is made of the following components by mass percentage: Modified cottonseed oil asphalt: 36%; Petrochemical asphalt: 12%; Waste engine oil: 7%; Thermoplastic elastomer powder: 5%; Waste tire rubber powder: 20%; Calcite powder: 20%.

2. The plant-based asphalt waterproofing membrane according to claim 1, characterized in that: The modified cottonseed oil asphalt is an esterification product obtained by reacting cottonseed oil asphalt with alcohol under the action of a catalyst.

3. A method for preparing a plant-based asphalt waterproofing membrane, characterized in that: The following steps are involved: S1. Pretreatment of cottonseed oil pitch: esterifying the cottonseed oil pitch with an excess of alcohol in the presence of a catalyst to reduce the polarity of the cottonseed oil pitch to obtain modified cottonseed oil pitch; S2. Preparation of a modifier: mixing a thermoplastic elastomer with waste engine oil and swelling the mixture at 180° C. to prepare a modifier; S3, preparation of blended modified asphalt: mixing the modified cottonseed oil asphalt with petrochemical asphalt to obtain an asphalt mixture; adding the modifier prepared in S2 to the asphalt mixture, and then adding waste tire rubber powder and calcite powder in sequence, and blending at 180° C. to obtain a blended modified asphalt; S4. Preparation of the roll material: coating the blended modified asphalt on the base cloth to prepare the plant-based asphalt waterproof roll material.

4. The preparation method according to claim 3, characterized in that The alcohol in S1 is anhydrous ethanol, and the amount of the excess alcohol is 1.4 times the theoretical molar amount of carboxyl groups in cottonseed oil pitch.

5. The preparation method according to claim 3, characterized in that The catalyst in S1 is sulfonic acid resin, and the amount used is 2% of the mass of cottonseed oil asphalt.

6. The preparation method according to claim 3, characterized in that The temperature of the esterification reaction in S1 is 110-130° C., and the reaction time is 4-6 hours.

7. The preparation method according to claim 3, characterized in that The mass ratio of modified cottonseed oil asphalt to petrochemical asphalt in S1 is 3:1.

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