Tough synergistic composite modified asphalt for hydraulic panel leveling layer and preparation method of tough synergistic composite modified asphalt

Abstract

The invention discloses tough synergistic composite modified asphalt for a hydraulic panel leveling layer and a preparation method of the tough synergistic composite modified asphalt, and the raw materials of the composite modified asphalt comprise matrix asphalt, a composite modifier, rubber oil and a vulcanizing agent, the composite modifier is prepared from the following raw materials: epoxidized castor oil, HDI (hexamethylene diisocyanate), a polymerization inhibitor, phthalic anhydride, an inhibitor and a chain terminator. HDI is dropwise added into epoxidized castor oil added with a polymerization inhibitor to generate epoxidized polyurethane, the epoxidized polyurethane, phthalic anhydride and an inhibitor form composite colloidal particles with a certain size through a granulator, and a long chain of the epoxidized castor oil and an HDI cross-linked network can effectively help the modified asphalt to realize toughness synergy; and the viscosity of the modified asphalt can be effectively reduced by controlling the cross-linking density, so that the material is more suitable for preparing the asphalt concrete which is tough, synergistic and long in service life and is used for a leveling cementing layer of a hydraulic asphalt concrete panel.

Description

Technical Field

[0001] The present invention relates to the technical field of asphalt modification, in particular to a strong and tough synergistic composite modified asphalt for hydraulic panel leveling layers and a preparation method thereof. Background Art

[0002] From top to bottom, hydraulic asphalt concrete panels can be divided into a sealing layer, an anti-seepage layer, a drainage layer, an anti-seepage base layer, a leveling bonding layer and a bottom cushion layer. The leveling bonding layer plays the role of supporting the upper structure and being closely integrated with the lower structure. It provides a flat and solid foundation for the upper layer, ensures that the anti-seepage layer is laid evenly, transfers stress, and prevents slippage and detachment between the upper and lower layers.

[0003] Currently, the materials widely used for leveling bonding layers are base asphalt and SBS modified asphalt. These asphalt materials have poor toughness, which makes the leveling bonding layer insufficiently strong to support the superstructure and effectively resist the damage caused by the upper load. It is easily affected by stress concentration and causes cracking.

[0004] Existing technologies use bio-based raw materials and polyols to form prepolymers through addition polymerization, which are then reacted with chain extenders to form polymer materials. These are then used in asphalt systems to enhance the material's toughness, tear resistance, and wear resistance. However, the reaction rate of polyurethane produced by the reaction of bio-based raw materials and polyols is relatively fast, and the reaction between isocyanate and hydroxyl groups is highly exothermic. Existing technologies still have the following problems:

[0005] 1. The temperature fluctuations during the reaction are large and difficult to control, affecting the performance of the synthetic material. Excessively fast reaction rates cause the system temperature to drop sharply, accelerating crosslinking, causing the synthesized modified asphalt to lose its processing properties and become uncontrollable, ultimately forming an irreversible gel.

[0006] 2. The increased viscosity of synthetic materials increases their sensitivity to temperature fluctuations. During the construction phase of hydraulic asphalt concrete in low-temperature environments, the high-viscosity asphalt tends to solidify quickly. However, its excellent dispersion properties at high temperatures are rapidly lost as the temperature decays. This results in insufficient interfacial bonding between the asphalt binder system and the aggregate particles, making it unable to effectively infiltrate the aggregate surface and form a continuous coating. This in turn affects the mechanical properties and durability of the asphalt binder, making it unsuitable for use as a leveling binder layer in hydraulic asphalt concrete panels. Summary of the Invention

[0007] The present invention addresses the shortcomings of the aforementioned prior art by providing a tough, synergistic composite modified asphalt for use in the leveling layer of hydraulic asphalt panels and its preparation method. The composite modified asphalt is prepared using materials such as epoxidized castor oil, HDI, a polymerization inhibitor, phthalic anhydride, an inhibitor, and a chain terminator. Base asphalt, rubber oil, and a vulcanizing agent are then added to produce the composite modified asphalt. The present invention effectively regulates the reaction process, enhancing the toughness, tear resistance, and wear resistance of the modified asphalt while reducing its viscosity and temperature sensitivity, making it suitable for use in the leveling binder layer of hydraulic asphalt concrete panels.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A composite modified asphalt for a strong and tough synergistic hydraulic asphalt concrete panel leveling layer, characterized in that the raw materials of the composite modified asphalt are proportioned as follows by mass:

[0010] 65-72 parts of base asphalt,

[0011] 22-28 parts of composite modified product,

[0012] 6-8 parts of rubber oil,

[0013] 0.3-0.4 parts of vulcanizing agent,

[0014] The raw materials of the composite modified product are proportioned as follows by mass:

[0015] 30-38 parts of epoxidized castor oil,

[0016] HDI (hexamethylene diisocyanate) 55-65 parts,

[0017] 0.5-1.0 parts of polymerization inhibitor,

[0018] 5-6 parts of phthalic anhydride,

[0019] 1.5-2.0 parts of chain terminator,

[0020] 0.2-0.3 parts of inhibitor.

[0021] Epoxidized castor oil is prepared by acid-catalyzed peroxidation of castor oil. This peroxidation reaction introduces epoxy groups into the oil. These groups cross-link with the isocyanate groups in HDI and the active hydrogens in asphalt, forming a more stable three-dimensional network. This enhances reactivity and improves the mechanical properties of the material. The strong interaction between the epoxy groups and the polar components of asphalt reduces phase separation and improves the interfacial compatibility between polyurethane and asphalt. The epoxidized structure reduces the hydrophilicity of the castor oil and enhances its hydrolysis resistance, allowing the material to maintain excellent sealing and mechanical properties even after long-term exposure to wind and rain, making it suitable for use in hydraulic engineering environments.

[0022] HDI has a flexible fatty chain structure, which gives polyurethane a soft segment. The flexible fatty chain and the rigid network of epoxidized castor oil can synergistically enhance the elongation at break of the composite modified asphalt. It combines long-chain flexibility with cross-linked rigidity, which can greatly improve the toughness of the material. The aliphatic HDI structure has strong resistance to UV aging, and combined with the hydrophobic properties of epoxidized castor oil, it can extend the outdoor service life of the material. It is suitable for hydraulic application scenarios such as long-term exposed leveling cementing layers and has weather resistance advantages. In addition, HDI has low volatility and low toxicity, meeting environmental requirements.

[0023] The long chains of epoxidized castor oil provide high toughness, and the HDI cross-linked network enhances rigidity, which can effectively help the modified asphalt achieve strong and tough synergy; and the epoxidized polyurethane has a soft segment (long chains of epoxidized castor oil)-hard segment (urethane group) microphase separation structure. The soft segment has a higher glass transition temperature, while the asphalt has a lower one, making the two complementary at low temperatures: the asphalt becomes brittle when entering the glassy state, while the soft segment still maintains the flexibility of the molecular chain, and can absorb and release stress through local movement of the molecular chain, delaying the viscosity growth of the system; and the three-dimensional network formed by the hard segment maintains the overall structural stability of the material to avoid low-temperature embrittlement. This dynamic network of soft and hard segment microphase separation can significantly reduce the sensitivity of asphalt to temperature loss, ensuring that the asphalt maintains construction fluidity after entering a low-temperature environment from a high-temperature construction environment.

[0024] Phthalic anhydride primarily acts as an interfacial compatibilizer, reacting its anhydride groups with the epoxy groups of epoxidized castor oil and the isocyanate groups of HDI to enhance the compatibility between the polyurethane network and the asphalt phase, while also regulating the curing reaction rate to avoid excessive cross-linking. However, the phthalic anhydride dosage should not be too high, as the ratio of phthalic anhydride to asphalt is fixed when the grafting reaction between phthalic anhydride and asphalt reaches equilibrium. As the amount of phthalic anhydride added increases, the strength, toughness, and other mechanical properties of the modified asphalt are no longer optimized but instead decline. Excessive phthalic anhydride can lead to excessively high cross-linking density in the polyurethane network, resulting in brittle polyurethane-asphalt interface.

[0025] The matrix asphalt is at least one of natural asphalt, petroleum asphalt and coal tar asphalt. Preferably, the matrix asphalt is 90# petroleum asphalt with a needle penetration (25°C) of 80-100 (0.1mm).

[0026] The chain terminator is at least one of thiobisphenol, quinone derivatives, and aromatic amines. The chain terminator chemically binds or neutralizes free radicals, blocking their chain reaction, inhibiting oxidation or degradation, and improving the asphalt's anti-aging ability.

[0027] The vulcanizing agent is at least one of dicumyl peroxide, sulfur, and di-tert-butyl peroxide. Its function is to form a stable three-dimensional polymer network through dynamic vulcanization, promote the cross-linking reaction between the composite modifier and asphalt, and improve the storage stability of the modified asphalt.

[0028] The polymerization inhibitor is at least one of p-toluenesulfonic acid, dibutyl phthalate, and p-hydroxyanisole. P-toluenesulfonic acid inhibits the condensation reaction between isocyanates and hydroxyl groups; dibutyl phthalate acts as a plasticizer, reducing system viscosity and delaying gelation; and p-hydroxyanisole captures free radicals to prevent HDI self-polymerization. This provides multiple polymerization inhibition mechanisms, allowing for targeted control of the reaction process based on environmental needs, preventing a sudden increase in system viscosity or premature gelation.

[0029] The inhibitor is at least one of BHT (butylated hydroxytoluene), dilauryl thiodipropionate, and diphenylamine. Its primary function is to inhibit excessive cross-linking between HDI and epoxidized castor oil, preventing excessive self-polymerization of HDI or rapid reaction with hydroxyl groups to form a rigid network, which can lead to excessive asphalt viscosity and reduced compaction. The inhibitor dynamically regulates the reactivity of HDI with hydroxyl / epoxy groups through a synergistic mechanism of free radical capture, catalyst poisoning, and intermediate stabilization, thereby balancing cross-linking density and workability.

[0030] The preparation method of a composite modified asphalt for a strong and tough synergistic hydraulic asphalt concrete panel leveling layer according to claim 1 comprises the following steps:

[0031] Step 1, preparing epoxidized polyurethane: adding 1-3% of a polymerization inhibitor to epoxidized castor oil, adding liquid HDI dropwise to the epoxidized castor oil at a temperature of 80-90°C, and stirring to generate epoxidized polyurethane, wherein the addition ratio of liquid HDI to epoxidized castor oil is between 1:1.45 and 1:2.15;

[0032] Step 2, preparing a composite modified product: to avoid local overheating, the epoxidized polyurethane, phthalic anhydride, inhibitor, and chain terminator are added in stages in the order described above, melt-blended by chemical action, and granulated in a granulator to obtain a composite modified product;

[0033] Step 3, preparing composite modified asphalt: adding the composite modifier and rubber oil to the base asphalt, slowly adding the vulcanizing agent after high-speed shearing, and obtaining the composite modified asphalt after swelling and development.

[0034] The temperature for adding liquid HDI in step 1 is 85°C; the isocyanate index R of the reaction between liquid HDI and epoxidized castor oil is 1.6 to 1.8, preferably 1.7, to prevent HDI from self-polymerizing due to its high activity. The fatty chain structure of HDI gradually polymerizes to form a soft segment, while the hard segment (urethane group) and the soft segment (epoxidized castor oil segment) are separated to ensure the high toughness of the material. At the same time, during the reaction of epoxidized castor oil and HDI to form polyurethane, the reaction rate is too fast, causing the system temperature to rise sharply, accelerating cross-linking, and ultimately forming an irreversible gel with a rapid increase in viscosity, affecting industrial production. Therefore, it is necessary to use an inhibitor to inhibit the rapid reaction of HDI with the hydroxyl groups of epoxidized castor oil. After adding the inhibitor, the system can maintain a low viscosity state without reducing the mechanical properties of the final polyurethane, which is beneficial to enhancing the toughness of the modified asphalt.

[0035] In step 3, the shear rate of high-speed shearing is 4000-6000 r / min, and the shearing time is 30-45 min, so as to ensure uniform dispersion of the composite modifier and avoid asphalt aging during the shear preparation process; the stirring speed of swelling and development is 200-300 r / min, and the stirring time is 90-120 min; the temperature of high-speed shearing and swelling and development is both 170-180°C.

[0036] Polyurethane is very easy to solidify and separate, and it is separated in layers in the asphalt system. This application prepares a composite modified product to form a homogenized composite granule, which enhances the compatibility of the polyurethane network with asphalt, reduces the phase separation problem, makes the polymer more evenly dispersed in the asphalt, and improves the homogeneity of the overall material. At the same time, the composite granule can regulate the cross-linking reaction process through the granulation process. The particle structure after granulation slows down the rapid reaction of HDI and hydroxyl groups through physical isolation. For example, inhibitors (such as BHT) in the composite granule can suppress the excessive cross-linking of HDI and epoxidized castor oil through free radical capture and reaction activity regulation. The particle structure formed after granulation allows the cross-linking density to be gradually released during the processing process, avoiding excessive cross-linking during the modification process to cause excessive viscosity or gelation, and ensuring construction performance.

[0037] The application of the composite modified asphalt according to claim 1 is characterized in that it is applied to the leveling bonding layer of hydraulic asphalt concrete panels.

[0038] The present invention has the following beneficial effects:

[0039] 1. The long chain of epoxidized castor oil provides high toughness, and the HDI cross-linked network enhances rigidity, which can synergistically enhance the toughness, tear resistance and wear resistance of the modified asphalt; and the epoxidized polyurethane has a soft segment (long chain of epoxidized castor oil)-hard segment (urethane group) microphase separation structure. The soft segment has a higher glass transition temperature, while the asphalt has a lower one, making the two complementary at low temperatures: the asphalt is prone to brittleness when entering the glassy state, while the soft segment still maintains the flexibility of the molecular chain, and can absorb and release stress through the local movement of the molecular chain, delaying the viscosity growth of the system; and the three-dimensional network formed by the hard segment maintains the overall structural stability of the material to avoid low-temperature embrittlement. This dynamic network of soft and hard segment microphase separation can significantly reduce the sensitivity of asphalt to temperature loss, ensuring that the asphalt maintains construction fluidity after entering a low-temperature environment from a high-temperature construction environment.

[0040] 2. This invention utilizes a multi-stage reaction control technology, adding polymerization inhibitors, inhibitors, and chain terminators in stages during the reaction to control the exothermic reaction and regulate the reaction progress. The polymerization inhibitors provide multiple inhibition mechanisms, rather than relying on a single acidic environment to inhibit the reaction. The inhibitors further control excessive crosslinking, while the chain terminators block the chain reaction. The three work synergistically to regulate crosslink density, reduce system viscosity, and thus reduce the temperature sensitivity of the modified asphalt.

[0041] 3. The present invention adopts a granulation process to prepare composite modified asphalt, regulates the cross-linking reaction process, controls the system temperature by segmented feeding, avoids local overheating, and the particle structure formed after granulation allows the cross-linking density to be gradually released during the processing, avoiding excessive cross-linking during the modification process that leads to excessive viscosity or gelation, thereby ensuring construction performance.

[0042] 4. The composite modified product prepared by the present invention has good compatibility with asphalt, which solves the processing difficulties of high-dosage polymer-modified asphalt caused by too fast reaction rate and overreaction, so that a higher amount of polymer can be incorporated into the modified asphalt system, thereby enhancing the toughness, tear resistance and wear resistance of the modified asphalt while reducing the sensitivity of the modified asphalt to temperature, making it more suitable for the leveling bonding layer of hydraulic asphalt concrete panels.

[0043] 5. The composite modified asphalt prepared by the present invention is resistant to ultraviolet aging and has strong hydrolysis resistance, which extends the service life of the material in the hydraulic environment; it has low toxicity and is not easy to volatilize, and its environmental performance is guaranteed; and the higher dosage of epoxidized castor oil reduces the cost, and is more suitable for the leveling bonding layer of hydraulic asphalt concrete panels that are strong and tough, not affected by temperature, and have a long service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] none. DETAILED DESCRIPTION

[0045] The present invention is further illustrated below by way of examples, but the scope of protection of the claims of the present invention is not limited by the examples.

[0046] The sources of the raw materials used in the examples of the present invention are as follows:

[0047] The matrix asphalt was 90# petroleum asphalt and 70# petroleum asphalt, purchased from Jiangsu Xinyue Asphalt Co., Ltd.

[0048] The chain terminator is one or more of thiobisphenol, quinone derivatives and aromatic amines, purchased from Hubei Xinrunde Chemical Co., Ltd.

[0049] Rubber oil was purchased from Jiangsu Zhonghong Green Environmental Protection Co., Ltd.

[0050] The vulcanizing agent is one or more of dicumyl peroxide, sulfur and di-tert-butyl peroxide, purchased from Shandong Xuchen Chemical Technology Co., Ltd.

[0051] Epoxidized castor oil was purchased from Jiangsu Shenglun Chemical Technology Co., Ltd.

[0052] HDI (hexamethylene diisocyanate) was purchased from Jiangsu Bosite Chemical Technology Co., Ltd.

[0053] The polymerization inhibitor is one or more of p-toluenesulfonic acid, dibutyl phthalate and p-hydroxyanisole, purchased from Wuhan Jiyesheng Chemical Co., Ltd.

[0054] Phthalic anhydride was purchased from Shandong Xuchen Chemical Technology Co., Ltd.

[0055] The inhibitor is one or more of BHT (butylated hydroxytoluene), dilauryl thiodipropionate and diphenylamine, and is purchased from Anhui Haihua Technology Group Co., Ltd.

[0056] Example 1

[0057] A strong and tough synergistic composite modified asphalt (1#) for a leveling layer of a hydraulic asphalt concrete panel, the composite modified asphalt being used for a leveling bonding layer of a hydraulic asphalt concrete panel, comprising the following components in parts by weight:

[0058]

[0059] The composite modified material is a mixture of epoxidized castor oil, HDI, polymerization inhibitor, phthalic anhydride, inhibitor and chain terminator.

[0060] in:

[0061] The matrix asphalt is 90# petroleum asphalt.

[0062] The composite modified material comprises the following components in parts by mass:

[0063]

[0064] The inhibitor is BHT.

[0065] The chain terminator is thiobisphenol.

[0066] The vulcanizing agent is dicumyl peroxide.

[0067] The polymerization inhibitor is p-toluenesulfonic acid.

[0068] The preparation method of the above-mentioned strong and tough synergistic composite modified asphalt for the leveling layer of hydraulic asphalt concrete panel comprises the following steps:

[0069] (1) 30 parts by mass of epoxidized castor oil were added with 0.5 parts by mass of a polymerization inhibitor, and 65 parts by mass of liquid HDI were added dropwise at 85°C. The mixture was stirred at a stirring speed of 500 r / min for 30 minutes to generate epoxidized polyurethane. The isocyanate index R of the reaction between liquid HDI and epoxidized castor oil was controlled to be 1.7.

[0070] (2) adding the prepared epoxidized polyurethane, 5 parts by mass of phthalic anhydride, 1.5 parts by mass of a chain terminator, and 0.2 parts by mass of an inhibitor in the order of polyurethane-phthalic anhydride-inhibitor-chain terminator, and performing chemical force melt blending, and preparing a composite modified product by granulating;

[0071] (3) Add 22 parts by mass of the composite modifier and 6 parts by mass of rubber oil to 72 parts by mass of 90# base asphalt, increase the temperature of the mixture to 175°C, shear at a high speed of 6000 r / min for 45 minutes, add 0.3 parts by mass of the vulcanizing agent, maintain the temperature at 175°C, stir at a speed of 300 r / min for 120 minutes to allow swelling and development, and obtain the composite modified asphalt.

[0072] Example 2

[0073] A composite modified asphalt (2#) for a strong and tough synergistic hydraulic asphalt concrete panel leveling layer, the composite modified asphalt is used for the leveling bonding layer of the hydraulic asphalt concrete panel, and comprises the following components in parts by weight:

[0074]

[0075] The composite modified material is a mixture of epoxidized castor oil, HDI, polymerization inhibitor, phthalic anhydride, inhibitor and chain terminator.

[0076] in:

[0077] The matrix asphalt is 70# petroleum asphalt.

[0078] The composite modified material comprises the following components in parts by mass:

[0079]

[0080] The inhibitor is dilauryl thiodipropionate.

[0081] The chain terminator is a quinone derivative.

[0082] The vulcanizing agent is sulfur.

[0083] The polymerization inhibitor is dibutyl phthalate.

[0084] The preparation method of the above-mentioned strong and tough synergistic composite modified asphalt for the leveling layer of hydraulic asphalt concrete panel comprises the following steps:

[0085] (1) 34 parts by mass of epoxidized castor oil were added with 0.7 parts by mass of a polymerization inhibitor, and 62 parts by mass of liquid HDI were added dropwise at 80°C. The mixture was stirred at a stirring speed of 300 r / min for 50 minutes to generate epoxidized polyurethane. The isocyanate index R of the reaction between liquid HDI and epoxidized castor oil was controlled to be 1.6.

[0086] (2) adding the prepared epoxidized polyurethane, 5 parts by mass of phthalic anhydride, 1.8 parts by mass of a chain terminator, and 0.3 parts by mass of an inhibitor in the order of polyurethane-phthalic anhydride-inhibitor-chain terminator, and melt-blending them under chemical action, and preparing a composite modified product by pelletizing;

[0087] (3) Add 26 parts by mass of the composite modifier and 7 parts by mass of rubber oil to 68 parts by mass of 70# base asphalt, increase the temperature of the mixture to 170°C, shear at a high speed of 4000 r / min for 30 minutes, add 0.3 parts by mass of the vulcanizing agent, maintain the temperature at 170°C, and stir at a speed of 200 r / min for 90 minutes to allow swelling and development to obtain the composite modified asphalt.

[0088] Example 3

[0089] A strong and tough synergistic composite modified asphalt (3#) for the leveling layer of hydraulic asphalt concrete panels. The composite modified asphalt is used for the leveling bonding layer of hydraulic asphalt concrete panels and comprises the following components in parts by weight:

[0090]

[0091] The composite modified material is a mixture of epoxidized castor oil, HDI, polymerization inhibitor, phthalic anhydride, inhibitor and chain terminator.

[0092] in:

[0093] The matrix asphalt is 90# petroleum asphalt.

[0094] The composite modified material comprises the following components in parts by mass:

[0095]

[0096] The inhibitor is diphenylamine.

[0097] The chain terminator is an aromatic amine.

[0098] The vulcanizing agent is di-tert-butyl peroxide.

[0099] The polymerization inhibitor is p-hydroxyanisole.

[0100] The preparation method of the above-mentioned strong and tough synergistic composite modified asphalt for the leveling layer of hydraulic asphalt concrete panel comprises the following steps:

[0101] (1) 38 parts by mass of epoxidized castor oil were added with 1.0 parts by mass of a polymerization inhibitor, and 60 parts by mass of liquid HDI were added dropwise at 90°C. The mixture was stirred at a stirring speed of 450 r / min for 30 minutes to generate epoxidized polyurethane. The isocyanate index R of the reaction between liquid HDI and epoxidized castor oil was controlled to be 1.7.

[0102] (2) adding the prepared epoxidized polyurethane, 5 parts by mass of phthalic anhydride, 2.0 parts by mass of a chain terminator, and 0.3 parts by mass of an inhibitor in the order of polyurethane-phthalic anhydride-inhibitor-chain terminator, and melt-blending them under chemical action, and preparing a composite modified product by pelletizing;

[0103] (3) Add 28 parts by mass of the composite modifier and 8 parts by mass of rubber oil to 65 parts by mass of 90# base asphalt, increase the temperature of the mixture to 180°C, shear at a high speed of 5500 r / min for 40 minutes, add 0.4 parts by mass of the vulcanizing agent, maintain the temperature at 180°C, and stir at a speed of 250 r / min for 100 minutes to allow swelling and development to obtain the composite modified asphalt.

[0104] Example 4

[0105] A strong and tough synergistic composite modified asphalt (4#) for the leveling layer of hydraulic asphalt concrete panels. The composite modified asphalt is used for the leveling bonding layer of hydraulic asphalt concrete panels and comprises the following components in parts by weight:

[0106]

[0107] The composite modified material is a mixture of epoxidized castor oil, HDI, polymerization inhibitor, phthalic anhydride and chain terminator.

[0108] in:

[0109] The matrix asphalt is 90# petroleum asphalt.

[0110] The composite modified material comprises the following components in parts by mass:

[0111]

[0112] The chain terminator is thiobisphenol.

[0113] The vulcanizing agent is dicumyl peroxide.

[0114] The polymerization inhibitor is p-toluenesulfonic acid.

[0115] The preparation method of the above-mentioned strong and tough synergistic composite modified asphalt for the leveling layer of hydraulic asphalt concrete panel comprises the following steps:

[0116] (1) 30 parts by mass of epoxidized castor oil were added with 0.5 parts by mass of a polymerization inhibitor, and 65 parts by mass of liquid HDI were added dropwise at 85°C. The mixture was stirred at a stirring speed of 500 r / min for 30 minutes to generate epoxidized polyurethane. The isocyanate index R of the reaction between liquid HDI and epoxidized castor oil was controlled to be 1.7.

[0117] (2) adding the prepared epoxidized polyurethane, 5 parts by mass of phthalic anhydride, and 1.5 parts by mass of a chain terminator in the order of polyurethane-phthalic anhydride-chain terminator, and melt-blending them by chemical action, and preparing a composite modified product by a granulator;

[0118] (3) Add 22 parts by mass of the composite modifier and 6 parts by mass of rubber oil to 72 parts by mass of 90# base asphalt, increase the temperature of the mixture to 175°C, shear at a high speed of 6000 r / min for 45 minutes, add 0.3 parts by mass of the vulcanizing agent, maintain the temperature at 175°C, stir at a speed of 300 r / min for 120 minutes to allow swelling and development, and obtain the composite modified asphalt.

[0119] In order to explore the strength and toughness of the composite modified asphalt prepared based on the above method, the compressive strength of the composite modified asphalt was measured at room temperature by a compression test, and the elongation at break was measured at low temperature by a tensile test. The performance of the modified asphalt was evaluated by the two indicators of compressive strength and elongation at break. The test results are shown in Table 1.

[0120] Table 1 Properties of composite modified asphalt obtained in Examples 1 to 4

[0121] sample Compressive strength (MPa) Elongation at break (%) viscosity Base asphalt 6.5 10.2 0.55 SBS modified asphalt 12.3 21.5 0.61 1# 16.4 27.1 1.53 2# 15.9 27.6 1.62 3# 16.7 26.8 1.58 4# 15.1 25.8 3.21

[0122] According to the test results in Table 1, it can be found that the performance of the composite modified asphalt in the experiment is significantly better than the most widely used SBS modified asphalt and matrix asphalt at this stage. The incorporation of epoxidized castor oil, HDI, polymerization inhibitor, phthalic anhydride, inhibitor and chain terminator has a significant improvement effect on the strong and tough synergistic performance of asphalt. Asphalt concrete made with appropriate grading is expected to become an ideal hydraulic asphalt concrete panel leveling binder layer material. Example 4 does not add inhibitors, and the viscosity is significantly higher than the other three groups. The cross-linking density is too large and the viscosity is relatively high. The addition of inhibitors can further regulate the degree of cross-linking of the macromolecular chain, significantly improve its low-temperature fluidity and mixing performance, and ensure that a uniform and dense asphalt film is formed inside the mixture.

[0123] The present invention adds HDI dropwise to epoxidized castor oil to which an inhibitor is added to generate epoxidized polyurethane, and forms composite granules of a certain size by a granulator with epoxidized polyurethane, phthalic anhydride, inhibitor and chain terminator, etc., which are better compatible with asphalt. The long chain of epoxidized castor oil and the cross-linked network of HDI can effectively help the modified asphalt achieve strong and tough synergy, enhance the elongation at break and low-temperature crack resistance of asphalt, and control the cross-linking density to effectively reduce the viscosity of the modified asphalt, making it less susceptible to solidification due to temperature. By using a high amount of polymer, the synthesized composite modified asphalt is more suitable for preparing asphalt concrete for the leveling bonding layer of hydraulic asphalt concrete panels with strong and tough synergy and long service life.

[0124] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the scope of protection of the present invention.

Claims

1. Strong and tough synergistic composite modified asphalt for hydraulic panel leveling layer, characterized by: The raw materials of the composite modified asphalt are proportioned in parts by mass as follows: 65-72 parts of base asphalt, 22-28 parts of composite modified product, 6-8 parts of rubber oil, 0.3-0.4 parts of vulcanizing agent, The raw materials of the composite modified product are proportioned as follows by mass: 30-38 parts of epoxidized castor oil, HDI 55-65 parts, 0.5-1.0 parts of polymerization inhibitor, 5-6 parts of phthalic anhydride, 1.5-2.0 parts of chain terminator, 0.2-0.3 parts of inhibitor.

2. The composite modified asphalt according to claim 1, characterized in that: The matrix asphalt is at least one of natural asphalt, petroleum asphalt and coal tar asphalt.

3. The composite modified asphalt according to claim 1, characterized in that: The chain terminator is at least one of thiobisphenol, quinone derivatives and aromatic amines.

4. The composite modified asphalt according to claim 1, characterized in that: The vulcanizing agent is at least one of dicumyl peroxide, sulfur and di-tert-butyl peroxide.

5. The composite modified asphalt according to claim 1, characterized in that: The polymerization inhibitor is at least one of p-toluenesulfonic acid, dibutyl phthalate and p-hydroxyanisole.

6. The composite modified asphalt according to claim 1, characterized in that: The inhibitor is at least one of BHT (butylated hydroxytoluene), dilauryl thiodipropionate and diphenylamine.

7. The method for preparing the strong and tough synergistic composite modified asphalt for the hydraulic panel leveling layer according to claim 1, characterized in that: Here are the steps: Step 1, preparing epoxidized polyurethane: adding 1-3% of a polymerization inhibitor to epoxidized castor oil, adding liquid HDI dropwise to the epoxidized castor oil at a temperature of 80-90° C., and stirring to generate epoxidized polyurethane, wherein the addition ratio of liquid HDI to epoxidized castor oil is between 1:1.45 and 1:2.15, and the isocyanate index R of the reaction of liquid HDI and epoxidized castor oil is 1.6-1.8; Step 2, preparing a composite modified product: adding epoxidized polyurethane, phthalic anhydride, inhibitor, and chain terminator in the order mentioned above in stages, melt-blending them by chemical action, and then granulating them into a composite modified product; Step 3: Preparation of composite modified asphalt: The composite modifier and rubber oil are added to the base asphalt, and the vulcanizing agent is slowly added after high-speed shearing, and the composite modified asphalt is obtained after swelling and development.

8. The preparation method according to claim 7, characterized in that: The temperature for dropwise adding liquid HDI in step 1 is 85° C., and the isocyanate index R of the reaction between liquid HDI and epoxidized castor oil is 1.

7.

9. The preparation method according to claim 7, characterized in that: In step 3, the shear rate of high-speed shearing is 4000-6000 r / min, and the shearing time is 30-45 min; the stirring speed of swelling and development is 200-300 r / min, and the stirring time is 90-120 min; the temperature of high-speed shearing and swelling and development is 170-180°C.

10. The use of the composite modified asphalt according to claim 1, characterized in that: Used for leveling bonding layer of hydraulic asphalt concrete panels.

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