A modified asphalt and its preparation and use

Abstract

This invention discloses a modified asphalt, its preparation method, and its application. The modified asphalt of this invention, by weight, comprises the following raw material components: base asphalt: 100 parts; compatibilizer: 3-6 parts; composite SBS modifier: 5-7 parts; stabilizer: 0.1-0.5 parts; stabilizer auxiliary agent: 0.05-0.3 parts; wherein the compatibilizer is a resin obtained after solvent deasphalting; and the composite SBS modifier is an SBS modifier that has undergone pre-degradation extrusion treatment. The polymer-modified asphalt of this invention exhibits good storage stability; after aging in a thin-film oven, the softening point decreases by less than 2°C, and its ductility, penetration, and other properties meet the technical specifications for racing track asphalt.

Description

Technical Field

[0001] This invention relates to an asphalt material and its preparation method, specifically to a modified asphalt, its preparation method, and its application. Background Technology

[0002] The FIA ​​Formula 1 World Championship (F1) is the world's highest level of motorsport, characterized by its speed, cost, and technology. To date, most Formula 1 racing circuits internationally use Shell modified asphalt, with the exception of the Melbourne Circuit in Australia and the Mazo Circuit in Italy, which use Esso modified asphalt. Shell's modified asphalt solutions are used in numerous Formula 1 circuits worldwide, including the Sakhir Circuit (Bahrain), Sepang Circuit (Malaysia), Marina Bay Street Circuit (Singapore), Hockenheim Circuit (Germany), and Yas Marina Circuit (Abu Dhabi).

[0003] Given the characteristics of Formula One racing, such as high speed variations (a maximum speed of 327 km / h and a minimum speed of only 80 km / h), sharp turns, and sudden braking, the selected SBS modified asphalt must possess excellent high-temperature stability and low-temperature ductility, as well as high elastic recovery, viscosity, cohesion, and shear strength. Taking the Ningbo F2 circuit as an example, its surface asphalt requires an SBS content of no less than 5.0% based on the base asphalt content, a softening point of no less than 75℃, and a penetration at 25℃ of no more than 65 0.1 mm. Not only are the requirements for ductility and segregation at 5℃ before and after aging far higher than those for ID-grade modified asphalt, but it also adds indicators such as a ductility at 25℃ greater than 100 cm, which are not required for ID-grade modified asphalt. The Chengdu F1 circuit, which is about to be built, further raises the requirements for softening point, penetration, and other indicators.

[0004] In addition, the modified asphalt for racing tracks now includes an index for changes in softening point before and after short-term aging, an area with limited research both domestically and internationally. Typically, it is required that the softening point increase after short-term aging not exceed 8℃ and the decrease not exceed 2℃, a requirement that poses a challenge in developing modified asphalt for racing tracks. Studies have shown that SBS modified asphalt is more prone to a decrease in softening point after short-term aging, with the decrease exceeding 2℃. The change in softening point after aging is determined by numerous factors, including the properties of the base asphalt, the degree of SBS crosslinking, network structure stability, and the degree of SBS degradation. Furthermore, it is difficult to balance changes in softening point with other indicators, significantly increasing the difficulty of preparing modified asphalt for racing tracks.

[0005] CN105038280B discloses an SBS-modified asphalt and its preparation method. This method uses polyphosphoric acid to replace part of the SBS modifier in the asphalt modification. While this reduces the modification cost to some extent, the low-temperature ductility and softening point are both low, and the softening point varies excessively. Furthermore, the amount of SBS modifier added to modified asphalt for racing tracks is limited, and polyphosphoric acid cannot be used as a substitute.

[0006] CN112300586A discloses an SBS modified asphalt stabilizer and SBS modified asphalt. The modified asphalt prepared by this method can inhibit the aging of the modified asphalt, but it is not good for the ductility at 25℃ and cannot inhibit the change of softening point.

[0007] In summary, the above methods cannot simultaneously ensure the high-temperature stability and low-temperature ductility of modified asphalt, and cannot solve the problem of excessive changes in softening point under high SBS content. As a result, the modified asphalt prepared cannot meet the requirements of track asphalt. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a modified asphalt, its preparation method, and its application. The polymer-modified asphalt of this invention exhibits good storage stability; after aging in a thin-film oven, its softening point decreases by less than 2°C, and its ductility, penetration, and other properties meet the technical specifications for racing track asphalt.

[0009] The first aspect of this invention provides a modified asphalt, comprising, by weight, the following raw material components:

[0010] Base bitumen: 100 parts;

[0011] Compatibilizer: 3-6 parts, preferably 3.5-5 parts;

[0012] Composite SBS modifier: 5-7 parts, preferably 5-6.2 parts;

[0013] Stabilizer: 0.1 to 0.5 parts, preferably 0.1 to 0.25 parts;

[0014] Stabilizer auxiliary agent: 0.05-0.3 parts, preferably 0.1-0.3 parts;

[0015] The compatibilizer is the resin obtained after solvent deasphalting;

[0016] The composite SBS modifier is an SBS modifier that has undergone pre-degradation extrusion treatment.

[0017] The properties of the base asphalt include: a penetration of 80–85 mm at 25°C, a softening point of 42–48°C, a dynamic viscosity of 155 Pa·s–165 Pa·s at 60°C, and a residual ductility of 10 cm–15 cm at 10°C. By mass fraction, the saturated components account for 13.1%–16.4%, the aromatic components account for 49.6%–54.5%, the resins account for 22.4%–27.1%, and the asphaltenes account for 7.3%–12.1%.

[0018] The base bitumen is preferably obtained by vacuum distillation of one or more of the following: crude oil from Sandy Land, Kuwait crude oil, and Basra crude oil.

[0019] The compatibilizer is an adhesive obtained through conventional solvent deasphalting processes in the art.

[0020] The compatibilizer has the following properties: kinematic viscosity of 50 mmHg at 100°C. 2 / s~65mm 2 / s, flash point is 206℃~220℃, by mass fraction, saturated fraction accounts for 30%~42%, aromatic fraction accounts for 48%~57%, resin accounts for 8%~13%, asphaltene content is less than 2%; weight average molecular weight is 1990~2140, molecular weight distribution width is 1.6~3.7.

[0021] The composite SBS modifier includes linear SBS modifiers and star-shaped SBS modifiers. The linear SBS modifier accounts for 45%–70% of the total mass of the composite SBS modifier; the star-shaped SBS modifier accounts for 30%–55% of the total mass of the composite SBS modifier.

[0022] The preparation method of the composite SBS modifier includes: putting linear SBS modifier and star-shaped SBS modifier into a grinding mill, shearing and grinding, and extruding and granulating to obtain the composite SBS modifier.

[0023] The linear SBS modifier has the following properties: a styrene to butadiene mass ratio of 12–20:80–88, and a tensile strength of 280–350 kg / cm². 2 It has an elongation at break of 800%–910% and a Shore hardness of 75±6HA.

[0024] The star-shaped SBS modifier has the following properties: the mass ratio of styrene to butadiene is 35-45:55-65, and the tensile strength is 200-300 kg / cm². 2 Its elongation at break is 720%–800%, and its Shore hardness is 90±5HA.

[0025] The stabilizer is a sulfur pretreatment agent.

[0026] The preparation process of the stabilizer is as follows:

[0027] The dried elemental sulfur is added to a closed reactor, stirred and heated to produce sulfur vapor, and then heated to the reaction temperature to carry out the reaction. After the reaction is completed, the mixture is rapidly cooled and refined to obtain the final stabilizer.

[0028] Furthermore, the drying conditions are as follows: the sulfur element is dried at 55℃~65℃ for 2h~4h.

[0029] The sealed reactor is preferably a high-pressure reactor. Before use, the sealed reactor is purged with nitrogen for 10–30 minutes to ensure that no air is present during the reaction. The heating temperature for sulfur vapor is 280–320°C, the reaction temperature is 500°C–700°C, preferably 550°C–700°C, the reaction pressure is 0.5–3.0 MPa, preferably 0.5–2.2 MPa, and the reaction time is 0.5–4 hours, preferably 1 hour–3.5 hours. The reaction is carried out under stirring at a speed of 300–500 r / min. The temperature is programmed at a rate of 2–5°C / min.

[0030] The stabilizer adjuvant is one or a mixture of several of the following: tetramethylthiuram disulfide and disodium dodecyl thiodipropionate, disodium octadecyl thiodipropionate, di(tridecyl) thiodipropionate, distearate thiodipropionate, zinc hydroxystannate, hydroquinone, zinc dimethyl thiocarbamate, zinc stearate, and thiocarbamate.

[0031] A second aspect of the present invention provides a method for preparing the above-mentioned modified asphalt, comprising the following steps:

[0032] (1) Preparation of composite SBS modifier;

[0033] (2) Preparation of stabilizers;

[0034] (3) Add some of the composite SBS modifier to the compatibilizer, and then shear and develop it for later use;

[0035] (4) Heat the base asphalt to a molten state, add the remaining composite SBS modifier, shear, and after shearing, add the material prepared in step (3) and stir to develop;

[0036] (5) Add a stabilizer to the material obtained in step (4) and continue stirring to develop;

[0037] (6) Add stabilizer and auxiliary agent to the material obtained in step (5), stir and develop to obtain modified asphalt.

[0038] In step (1), the preparation process of the composite SBS modifier is as follows:

[0039] Linear SBS modifier and star-shaped SBS modifier are fed into a grinding mill, sheared and ground, and then extruded and granulated to obtain a composite SBS modifier.

[0040] In step (1), the shearing and grinding temperature is 120℃~150℃, preferably 125℃~146℃. The shearing and grinding time is 20~40min. The extrusion granulation preferably uses a twin-screw extruder. The number of extrusions is 1~5 times, preferably 3 times. The first extrusion temperature is 120℃~130℃, and the screw speed is 180~300r / min. The second extrusion temperature is between 130℃~140℃, and the screw speed is between 320~450r / min. The third extrusion temperature is between 145℃~160℃, and the screw speed is between 500~650r / min. The temperature of each subsequent extrusion is higher than that of the previous extrusion.

[0041] In step (2), the preparation process of the stabilizer is as follows:

[0042] The dried elemental sulfur is added to a closed reactor, stirred and heated to produce sulfur vapor, and then heated to the reaction temperature to carry out the reaction. After the reaction is completed, the mixture is rapidly cooled and refined to obtain the final stabilizer.

[0043] Furthermore, the drying conditions are as follows: the sulfur element is dried at 55℃~65℃ for 2h~4h.

[0044] The sealed reactor is preferably a high-pressure reactor. Before use, the sealed reactor is purged with nitrogen for 10–30 minutes to ensure that no air is present during the reaction. The heating temperature for sulfur vapor is 280–320°C, the reaction temperature is 500°C–700°C, preferably 550°C–700°C, the reaction pressure is 0.5–3.0 MPa, preferably 0.5–2.2 MPa, and the reaction time is 0.5–4 hours, preferably 1 hour–3.5 hours. The reaction is carried out under stirring at a speed of 300–500 r / min. The temperature is programmed at a rate of 2–5°C / min.

[0045] In step (3), the amount of the composite SBS modifier is 30% to 70% of the total weight of the composite modifier, preferably 40% to 65%. The shear rate is 3000 to 5000 r / min, preferably 3000 to 4500 r / min, the shearing time is 20 to 40 min, and the required temperature during shearing is 120℃ to 145℃, preferably 125℃ to 135℃. The development can be done by static development, the development temperature is 130℃ to 145℃, and the development time is 4 h to 8 h.

[0046] In step (4), the heating temperature of the base asphalt is 130–145°C; both shearing and stirring development are carried out under a protective gas, preferably an inert gas and / or N2. The shearing rate is 4000–6000 r / min, preferably 4000–5500 r / min, the shearing time is 60–80 min, and the required temperature during shearing is 170–185°C. The stirring speed is 600–800 r / min, the development time is 20–40 min, and the development temperature is 150°C–195°C, preferably 170°C–180°C.

[0047] In step (5), the stabilizer is preferably added in several portions, with an interval of 20 to 40 minutes between each addition; preferably, it is added slowly in two separate additions. The stirring speed is 600 to 800 r / min, the development time is 3 to 4 hours, and the development temperature is 150°C to 195°C, preferably 170°C to 180°C.

[0048] In step (6), the stirring speed is 600-800 r / min, the development time is 0.5 h-1.2 h, and the development temperature is 150 ℃-180 ℃, preferably 165 ℃-180 ℃.

[0049] A third aspect of the present invention provides an application of the modified asphalt in a racetrack.

[0050] Compared with the prior art, the modified asphalt and its preparation method of the present invention have the following advantages:

[0051] (1) The present invention uses the resin prepared by solvent deasphalting process as a compatibilizer, and combines it with composite SBS modifier, stabilizer, stabilizer auxiliary agent and matrix asphalt. This can greatly improve the storage stability of modified asphalt, meet the requirements of high SBS content for track asphalt, and avoid excessive changes in softening point. It is particularly suitable as track asphalt.

[0052] (2) The present invention selects SBS with different structural properties for compounding and use. The composite SBS modifier is not a simple mechanical mixing of two SBS modifiers, but an SBS modifier that has undergone pre-degradation extrusion treatment and is then combined with other components. This makes the modified asphalt have better high-temperature stability and low-temperature elongation, avoiding the problem of significant decrease in softening point after short-term aging. In particular, it can achieve a softening point decrease of less than 2°C. A slight increase in softening point is beneficial to the performance of asphalt materials. As long as the increase in softening point is controlled to not exceed 5°C or 8°C, it is acceptable.

[0053] (3) The stabilizer used in this invention can maintain the long-term cross-linking reaction of the modifier, and the network structure is further formed and optimized during short-term aging and thermal storage, which improves the softening point of the modified asphalt, prevents the problem of excessive decrease in softening point after aging, and increases the storage stability of the modified asphalt. The stabilizer can also effectively control the uniformity of the cross-linking reaction rate, making the density and strength of the formed network structure more reasonable, which is conducive to improving the low-temperature and medium-temperature ductility of the modified asphalt.

[0054] (4) The stabilizer additives used in this invention can not only work synergistically with stabilizers to regulate reaction rate and progress and improve the overall performance of modified asphalt, but also inhibit the degradation of polymer modifiers in a hot and oxygen environment, thereby strengthening the stability of the modified asphalt network structure and suppressing changes in softening point. Detailed Implementation

[0055] The technical solution of the present invention is further described below through embodiments, but these embodiments cannot limit the scope of protection of the present invention, and the percentages involved are mass fractions.

[0056] In this invention, conventional indicators such as softening point and penetration are tested in accordance with the requirements of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering JTG E20-2011".

[0057] Example 1

[0058] Preparation of stabilizers:

[0059] Sublimed sulfur, dried in an oven at 60°C for 2.5 hours, was added to a high-pressure reactor that had been purged with nitrogen for 30 minutes. The reactor was heated to sulfur vapor at 300°C and then heated to 560°C at a programmed rate of 5°C / min. The reactor was then stirred at 450 r / min for 2 hours, with the pressure maintained at 1.2 MPa during the reaction. After the reaction was completed, the reactor was injected into a liquid nitrogen atmosphere for rapid cooling. The cooled solid product was then ground and passed through a 100-mesh (0.147 mm) standard sieve. The sieved product was collected and stored at -25°C for later use.

[0060] Preparation of modified asphalt:

[0061] (1) Linear SBS modifier and star-shaped SBS modifier (linear SBS modifier accounts for 65 wt% of the total amount, and the linear SBS modifier has the following properties: the mass ratio of styrene to butadiene is 20:80, and the tensile strength is 300 kg / cm²) 2 The elongation at break is 820%, and the Shore hardness is 75HA. The star-shaped SBS modifier has the following properties: the mass ratio of styrene to butadiene is 40:60, and the tensile strength is 250 kg / cm². 2A modifier with an elongation at break of 750% and a Shore hardness of 90HA was fed into a grinding mill and sheared and ground at 130℃ for 40 minutes until the two were evenly mixed. The evenly mixed modifier was then extruded and granulated three times. The first extrusion temperature was 125℃ and the screw speed was 200 r / min. The second extrusion temperature was 135℃ and the screw speed was 350 r / min. The third extrusion temperature was 155℃ and the screw speed was 500 r / min, thus obtaining a composite SBS modifier.

[0062] (2) Add 2.1 parts of the composite SBS modifier prepared in step (1) to 4 parts of compatibilizer (the resin obtained by solvent deasphalting process, with a kinematic viscosity of 60 mmHg at 100℃). 2 The sample has a flash point of 212℃ and, by mass fraction, comprises 33% saturated matter, 56.5% aromatic matter, 10% resin, and 0.5% asphaltenes; its weight-average molecular weight is 2090, and its molecular weight distribution width is 2.7. It was sheared at 135℃ for 30 min at a shear rate of 4000 r / min. After shearing, it was allowed to stand in a 135℃ oven for 6 h for later use.

[0063] (3) 100 parts of base asphalt (prepared from pure crude sand, with a penetration of 810.1 mm at 25℃, a softening point of 46℃, a dynamic viscosity of 158 Pa·s at 60℃, and a residual ductility (10℃) of 13 cm, and by mass fraction, saturated components account for 14.1%, aromatic components account for 54.1%, resins account for 23.2%, and asphaltenes account for 8.6%) were heated to a fluid state at 135℃, and 3 parts of the composite SBS modifier prepared in step (1) were added. The mixture was then subjected to high-speed shearing at 175℃ under a N2 atmosphere for 60 min at a shearing rate of 4000 r / min. After shearing, the material prepared in step (2) was added, and the mixture was stirred at 170℃ for 30 min at a stirring speed of 600 r / min.

[0064] (4) Slowly add 0.11 parts of the stabilizer prepared above to the material in step (3), and add another 0.11 parts of the same stabilizer after 30 minutes. Each addition is completed within 5 minutes. After the addition is completed, continue stirring and developing for 3 hours. The development temperature is 175℃ and the stirring speed is 800r / min.

[0065] (5) Add 0.15 parts of stabilizer additive (a mixture of tetramethylthiuram disulfide, zinc hydroxystannate, and di(tridecyl) thiodipropionate, wherein, based on the total mass of the stabilizer, the content of tetramethylthiuram disulfide is 30%, the content of zinc hydroxystannate is 38%, and the content of di(tridecyl) thiodipropionate is 32%) to the material in step (4), stir at 170°C for 1 hour at a stirring speed of 600 r / min to obtain the final modified asphalt A1 for the racetrack.

[0066] Example 2

[0067] (1) Linear SBS modifier and star-shaped SBS modifier (the linear SBS modifier accounts for 70% of the total amount, and the properties of the linear SBS modifier and star-shaped SBS modifier are the same as in Example 1) are put into a grinding mill and sheared and ground at 130°C for 40 minutes until they are evenly mixed. The evenly mixed modifier is extruded and granulated three times. The first extrusion temperature is 125°C and the screw speed is 250 r / min. The second extrusion temperature is 135°C and the screw speed is 350 r / min. The third extrusion temperature is 150°C and the screw speed is 550 r / min to obtain the composite SBS modifier.

[0068] (2) Add 3 parts of the composite SBS modifier prepared in step (1) to 4 parts of compatibilizer (properties as in Example 1), and shear at 135°C for 30 min at a shear rate of 4000 r / min. After shearing, let it stand in an oven at 135°C for 5 h for later use.

[0069] (3) Heat 100 parts of base asphalt (properties as in Example 1) to a fluid state at 135°C, add 2.2 parts of the composite SBS modifier prepared in step (1), and shear at high speed for 60 min at 175°C under a N2 atmosphere, with a shear rate of 3500 r / min. After shearing, add the material prepared in step (2), and stir at 170°C for 30 min at a stirring speed of 600 r / min.

[0070] (4) Slowly add 0.12 parts of stabilizer (preparation method is the same as in Example 1) to the material in step (3), and add another 0.12 parts of the same stabilizer after 30 min. Each addition is completed within 5 min. After the addition is completed, continue stirring and developing for 3.5 h. The development temperature is 175℃ and the stirring speed is 800 r / min.

[0071] (5) Add 0.2 parts of stabilizer additive (same as in Example 1) to the material in step (4), stir at 170°C for 40 minutes at a stirring speed of 600 r / min to obtain the final modified asphalt A2 for track use.

[0072] Example 3

[0073] (1) Linear SBS modifier and star-shaped SBS modifier (the linear SBS modifier accounts for 50% of the total amount, and the linear SBS modifier has the following properties: the mass ratio of styrene to butadiene is 20:80, and the tensile strength is 300 kg / cm²) 2 The elongation at break is 820%, and the Shore hardness is 75HA. The star-shaped SBS modifier has the following properties: the mass ratio of styrene to butadiene is 35:65, and the tensile strength is 260 kg / cm². 2A modifier with an elongation at break of 757% and a Shore hardness of 93HA was fed into a grinding mill and sheared and ground at 130℃ for 40 minutes until the two were evenly mixed. The evenly mixed modifier was then extruded and granulated three times. The first extrusion temperature was 130℃ and the screw speed was 300 r / min. The second extrusion temperature was 135℃ and the screw speed was 380 r / min. The third extrusion temperature was 160℃ and the screw speed was 600 r / min, thus obtaining a composite SBS modifier.

[0074] (2) Add 2.1 parts of the composite SBS modifier prepared in step (1) to 4 parts of compatibilizer (the resin obtained by solvent deasphalting process, with a kinematic viscosity of 65 mmHg at 100°C). 2 / s, flash point 215℃, by mass fraction, saturated fraction 35%, aromatic fraction 54.5%, resin 10%, asphaltenes 0.5%; weight average molecular weight 2100, molecular weight distribution width 2.4), sheared at 135℃ for 30 min, shear rate 4000 r / min. After shearing, it was placed in a 135℃ oven for 6 h for later use.

[0075] (3) 100 parts of base asphalt (prepared from pure Basra crude oil, with a penetration of 830.1 mm at 25℃, a softening point of 45.8℃, a dynamic viscosity of 158 Pa·s at 60℃, and a residual ductility (10℃) of 14 cm, and by mass fraction, saturated content of 15.1%, aromatic content of 53.6%, resin content of 24.1%, and asphaltenes content of 7.2%) were heated to a fluid state at 135℃. 3.3 parts of the composite SBS modifier prepared in step (1) were added, and the mixture was sheared at high speed for 60 min in a N2 atmosphere at 175℃ at a shear rate of 4000 r / min. After shearing, the material prepared in step (2) was added, and the mixture was stirred at 170℃ for 30 min at a stirring speed of 600 r / min.

[0076] (4) Slowly add 0.11 parts of stabilizer (preparation method is the same as in Example 1) to the material in step (3), and add 0.09 parts of stabilizer after 30 minutes. Each addition is completed within 5 minutes. After the addition is completed, continue stirring and developing for 3 hours. The development temperature is 175℃ and the stirring speed is 800r / min.

[0077] (5) Add 0.15 parts of stabilizer additive (a mixture of tetramethylthiuram disulfide, dodecayl thiodipropionate, and zinc dimethyl thiocarbamate, wherein, based on the total mass of the stabilizer, the content of tetramethylthiuram disulfide is 35%, the content of dodecayl thiodipropionate is 40%, and the content of zinc dimethyl thiocarbamate is 25%) to the material in step (4), stir at 170°C for 1 hour at a stirring speed of 600 r / min to obtain the final modified asphalt A3 for the racetrack.

[0078] Example 4

[0079] (1) Linear SBS modifier and star-shaped SBS modifier (the linear SBS modifier accounts for 45% of the total amount, and the properties of the linear SBS modifier and star-shaped SBS modifier are the same as in Example 3) are put into a grinding mill and sheared and ground at 130°C for 40 minutes until they are evenly mixed. The evenly mixed modifier is extruded and granulated three times. The first extrusion temperature is 125°C and the screw speed is 280 r / min. The second extrusion temperature is 140°C and the screw speed is 350 r / min. The third extrusion temperature is 150°C and the screw speed is 520 r / min to obtain the composite SBS modifier.

[0080] (2) Add 2.3 parts of the composite SBS modifier prepared in step (1) to 4 parts of compatibilizer (properties as in Example 3), and shear at 135°C for 30 min at a shear rate of 3500 r / min. After shearing, let it stand in an oven at 135°C for 7 h for later use.

[0081] (3) Heat 100 parts of base asphalt (properties as in Example 3) to a fluid state at 135°C, add 3.2 parts of the composite SBS modifier prepared in step (1), and shear at high speed for 60 min at 175°C under a N2 atmosphere, with a shear rate of 4000 r / min. After shearing, add the material prepared in step (2), and stir at 175°C for 30 min at a stirring speed of 600 r / min.

[0082] (4) Slowly add 0.125 parts of stabilizer (preparation method is the same as in Example 1) to the material in step (3), and add 0.11 parts of stabilizer after 30 min. Each addition is completed within 5 min. After the addition is completed, continue stirring and developing for 4 h. The development temperature is 175℃ and the stirring speed is 800 r / min.

[0083] (5) Add 0.25 parts of stabilizer additive (same as in Example 3) to the material in step (4), stir at 170°C for 50 minutes at a stirring speed of 600 r / min to obtain the final modified asphalt A4 for track use.

[0084] Example 5

[0085] Preparation of stabilizers:

[0086] Sublimed sulfur, dried in an oven at 60°C for 3 hours, was added to a high-pressure reactor that had been purged with nitrogen for 30 minutes. The reactor was heated to 320°C to produce sulfur vapor, and then the temperature was increased to 600°C at a programmed rate of 5°C / min. The reactor was then stirred at 450 r / min for 3 hours, with the pressure maintained at 1.4 MPa during the reaction. After the reaction was completed, the reactor was injected into a liquid nitrogen atmosphere for rapid cooling. The cooled solid product was then ground and passed through a 100-mesh (0.147 mm) standard sieve. The sieved product was collected and stored at -25°C for later use.

[0087] Preparation of modified asphalt:

[0088] (1) Linear SBS modifier and star-shaped SBS modifier (the linear SBS modifier accounts for 50% of the total amount, and the linear SBS modifier has the following properties: the mass ratio of styrene to butadiene is 20:80, and the tensile strength is 300 kg / cm²) 2 The elongation at break is 820%, and the Shore hardness is 75HA. The star-shaped SBS modifier has the following properties: the mass ratio of styrene to butadiene is 35:65, and the tensile strength is 260 kg / cm². 2 A modifier with an elongation at break of 757% and a Shore hardness of 93HA was fed into a grinding mill and sheared and ground at 130℃ for 40 minutes until the two were evenly mixed. The evenly mixed modifier was then extruded and granulated three times. The first extrusion temperature was 130℃ and the screw speed was 300 r / min. The second extrusion temperature was 135℃ and the screw speed was 380 r / min. The third extrusion temperature was 160℃ and the screw speed was 600 r / min, thus obtaining a composite SBS modifier.

[0089] (2) Add 3 parts of the composite SBS modifier prepared in step (1) to 4 parts of compatibilizer (properties as in Example 1), and shear at 135°C for 30 min at a shear rate of 4000 r / min. After shearing, let it stand in an oven at 135°C for 5 h for later use.

[0090] (3) Heat 100 parts of base asphalt (properties as in Example 3) to a fluid state at 135°C, add 3.2 parts of the composite SBS modifier prepared in step (1), and shear at high speed for 60 min at 175°C under a N2 atmosphere, with a shear rate of 4000 r / min. After shearing, add the material prepared in step (2), and stir at 175°C for 30 min at a stirring speed of 600 r / min.

[0091] (4) Slowly add 0.11 parts of the stabilizer prepared above to the material in step (3), and add another 0.11 parts of the same stabilizer after 30 minutes. Each addition is completed within 5 minutes. After the addition is completed, continue stirring and developing for 3 hours. The development temperature is 175℃ and the stirring speed is 800r / min.

[0092] (5) Add 0.25 parts of stabilizer additive (same as in Example 3) to the material in step (4), stir at 170°C for 50 minutes at a stirring speed of 600 r / min to obtain the final modified asphalt A5 for the track.

[0093] Comparative Example 1

[0094] 100 parts of base asphalt (properties as in Example 1) were heated to a fluid state at 135°C, and 5.2 parts of linear SBS modifier (same as in Example 1) were added. The mixture was then subjected to high-speed shearing at 175°C for 60 minutes at a shear rate of 4000 r / min. After shearing, 0.225 parts of stabilizer (same as in Example 1) were slowly added, and the mixture was stirred and developed for 4 hours at a development temperature of 175°C and a stirring speed of 800 r / min to obtain the final modified asphalt B1.

[0095] Comparative Example 2

[0096] 100 parts of base asphalt (properties as in Example 1) were heated to a fluid state at 135°C, and 5.2 parts of star-shaped SBS modifier (same as in Example 1) were added. The mixture was then subjected to high-speed shearing at 175°C for 60 minutes at a shear rate of 4000 r / min. After shearing, 0.225 parts of stabilizer (same as in Example 1) were slowly added, and the mixture was stirred and developed for 4 hours at a development temperature of 175°C and a stirring speed of 800 r / min to obtain the final modified asphalt B2.

[0097] Comparative Example 3

[0098] 100 parts of base asphalt (properties as in Example 1) were heated to a fluid state at 135°C. Then, 3.3 parts of linear SBS modifier (properties as in Example 1) and 1.8 parts of star-shaped SBS modifier (properties as in Example 1) were added. The mixture was then subjected to high-speed shearing at 175°C for 60 minutes at a shear rate of 4000 r / min. After shearing, 0.225 parts of stabilizer (same as in Example 1) were slowly added, and the mixture was stirred and developed for 4 hours at 175°C and a stirring speed of 800 r / min to obtain the final modified asphalt B3.

[0099] Comparative Example 4

[0100] Same as Example 1, except that in step (1), linear SBS modifier and star-shaped SBS modifier (linear SBS modifier accounts for 65wt% of the total amount) are directly mechanically mixed to obtain composite SBS. The other steps are the same to obtain the final modified asphalt B4.

[0101] Comparative Example 5

[0102] Same as Example 1, except that step (2) is omitted. 5.1 parts of the composite SBS modifier prepared in step (1) are directly added to the base asphalt heated to a fluid state to obtain the final modified asphalt B5.

[0103] Comparative Example 6

[0104] Same as Example 1, except that in step (4), the stabilizer is replaced with 0.11 parts of elemental sulfur to obtain the final modified asphalt B6.

[0105] Comparative Example 7

[0106] Same as Example 1, except that no stabilizer or auxiliary agent is added during the preparation process to obtain the final modified asphalt B7.

[0107] Test case

[0108] The main property indicators of the modified asphalt for the track obtained in the examples and comparative examples were tested, and the specific test results are shown in Table 1.

[0109] Table 1. Main properties of the asphalt materials obtained in the examples and comparative examples.

[0110]

[0111]

[0112] The scope of protection of this invention is not limited to the above embodiments, but is defined by the claims. Those skilled in the art can make appropriate modifications to these embodiments without departing from the technical concept and spirit of this invention, and these modified embodiments are also included within the scope of protection of this invention.

Claims

1. A modified asphalt, comprising, by weight, the following raw material components: Base bitumen: 100 parts; Compatibilizer: 3-6 parts; Composite SBS modifier: 5-7 parts; Stabilizer: 0.1~0.5 parts; Stabilizer adjuvant: 0.05~0.3 parts; The compatibilizer is the resin obtained after solvent deasphalting; The composite SBS modifier is an SBS modifier that has undergone pre-degradation extrusion treatment; the composite SBS modifier includes linear SBS modifier and star-shaped SBS modifier; wherein the linear SBS modifier accounts for 45% to 70% of the total mass of the composite SBS modifier; and the star-shaped SBS modifier accounts for 30% to 55% of the total mass of the composite SBS modifier. The preparation method of the composite SBS modifier includes: Linear SBS modifier and star-shaped SBS modifier are put into a grinding mill, sheared and ground, and then extruded and granulated to obtain composite SBS modifier. The shearing and grinding temperature is 120℃~150℃, the shearing and grinding time is 20~40min, the extrusion is performed 3 times, the first extrusion temperature is 120℃~130℃, the screw speed is 180~300r / min, the second extrusion temperature is 130℃~140℃, the screw speed is 320~450r / min, and the third extrusion temperature is 145℃~160℃, the screw speed is 500~650r / min, wherein the extrusion temperature of each subsequent extrusion is higher than that of the previous extrusion. The stabilizer is a sulfur pretreatment agent; The stabilizer adjuvant is one or a mixture of several of the following: tetramethylthiuram disulfide and disodium dodecyl thiodipropionate, disodium octadecyl thiodipropionate, di(tridecyl) thiodipropionate, distearate thiodipropionate, zinc hydroxystannate, hydroquinone, zinc dimethyl dithiocarbamate, zinc stearate, and thiocarbamate. The properties of the compatibility agent include: a kinematic viscosity at 100°C of 50 mm 2 / s~65 mm 2 / s, a flash point of 206°C~220°C, a saturates content of 30%~42%, an aromatics content of 48%~57%, a resins content of 8%~13%, and an asphaltene content of less than 2% by mass; a weight average molecular weight of 1990~2140, and a molecular weight distribution width of 1.6~3.7; The preparation process of the stabilizer is as follows: dried elemental sulfur is added to a closed reactor, stirred and heated to produce sulfur vapor, and then heated to the reaction temperature to carry out the reaction. After the reaction is completed, the stabilizer is rapidly cooled and refined to obtain the final stabilizer.

2. The modified asphalt according to claim 1, characterized in that, By weight, it includes the following raw material components: Base bitumen: 100 parts; Compatibilizer: 3.5~5 parts; Composite SBS modifier: 5~6.2 parts; Stabilizer: 0.1~0.25 parts; Stabilizer adjuvant: 0.1~0.3 parts.

3. The modified asphalt according to claim 1, characterized in that, The properties of the base asphalt include: a penetration of 80~85 0.1 mm at 25℃, a softening point of 42℃~48℃, a dynamic viscosity of 155 Pa·s~165 Pa·s at 60℃, and a residual ductility of 10 cm~15 cm at 10℃. By mass fraction, the saturated components account for 13.1%~16.4%, the aromatic components account for 49.6%~54.5%, the resins account for 22.4%~27.1%, and the asphaltenes account for 7.3%~12.1%.

4. The modified asphalt according to claim 2 or 3, characterized in that, The base bitumen is obtained by vacuum distillation of one or more of the following: crude oil from Sandy Land, Kuwait crude oil, and Basra crude oil.

5. The modified asphalt according to claim 1, characterized in that, The linear SBS modifier has the following properties: the mass ratio of styrene to butadiene is 12~20:80~88, and the tensile strength is 280~350 kg / cm². 2 Elongation at break is 800%~910%, Shore hardness is 75±6HA; and / or, The star-shaped SBS modifier has the following properties: the mass ratio of styrene to butadiene is 35~45:55~65, and the tensile strength is 200~300 kg / cm². 2 It has an elongation at break of 720%~800% and a Shore hardness of 90±5HA.

6. A method for preparing modified bitumen according to any one of claims 1-5, comprising the following steps: (1) Preparation of composite SBS modifier; (2) Preparation of stabilizers; (3) Add a portion of the composite SBS modifier to the compatibilizer, and then shear and develop it for later use; (4) Heat the base asphalt to a molten state, add the remaining composite SBS modifier, shear, and after shearing, add the material prepared in step (3) and stir to develop; (5) Add a stabilizer to the material obtained in step (4) and continue stirring to develop; (6) Add stabilizer and auxiliary agent to the material obtained in step (5), stir and develop to obtain modified asphalt.

7. The method according to claim 6, characterized in that, In step (1), the preparation process of the composite SBS modifier is as follows: linear SBS modifier and star-shaped SBS modifier are put into a grinding mill, sheared and ground, and extruded and granulated to obtain the composite SBS modifier.

8. The method according to claim 6, characterized in that, In step (2), the preparation process of the stabilizer is as follows: The dried elemental sulfur is added to a closed reactor, stirred and heated to produce sulfur vapor, and then heated to the reaction temperature to carry out the reaction. After the reaction is completed, the mixture is rapidly cooled and refined to obtain the final stabilizer.

9. The method according to claim 6, characterized in that, In step (3), the amount of the partial composite SBS modifier is 30% to 70% of the total weight of the composite modifier; the shear rate is 3000 to 5000 r / min, the shearing time is 20 to 40 min, and the temperature required for shearing is 120℃ to 145℃; the development temperature is 130℃ to 145℃, and the development time is 4h to 8h.

10. The method according to claim 6, characterized in that, In step (4), the base asphalt is heated to a temperature of 130-145℃; the shearing and stirring development are both carried out under a protective gas; the shearing rate is 4000-6000 r / min, the shearing time is 60-80 min, and the temperature required for shearing is 170-185℃; the stirring speed is 600-800 r / min, the development time is 20-40 min, and the development temperature is 150℃-195℃.

11. The method according to claim 6, characterized in that, In step (5), the stabilizer is added in several batches, with an interval of 20 to 40 minutes between each addition; the stirring speed is 600 to 800 r / min, the development time is 3 to 4 hours, and the development temperature is 150°C to 195°C.

12. The method according to claim 11, characterized in that, In step (5), the stabilizer is added in two separate steps.

13. The application of the modified asphalt according to any one of claims 1-5 or the modified asphalt prepared by the method according to any one of claims 6-12 in a racetrack.

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