Process for the preparation of polymer modified bitumen

Abstract

The application discloses a preparation method of polymer modified asphalt. The method comprises the following steps: (1) mixing matrix asphalt in a molten state with a compatibilizer, and then performing first heating; (2) mixing the material after the first heating with a polymer and a cross-linking promoter, and shearing; (3) performing second heating on the material after the shearing in the step (2), and performing development reaction under stirring; (4) after the development reaction is completed, cooling, adding a cross-linking terminator, and stirring to obtain polymer modified asphalt; wherein the cross-linking terminator is a combination of a hindered piperidine derivative and a benzotriazole compound. The application can keep the performance of the polymer modified asphalt at a required performance index, and achieves the purpose of controllable modification degree.

Description

Technical Field

[0001] This invention relates to the field of asphalt, and more specifically to a method for preparing polymer-modified asphalt. Background Technology

[0002] SBS modified asphalt is currently the most widely used polymer-modified asphalt, improving both the high and low temperature properties of asphalt and its temperature sensitivity. After the SBS polymer is uniformly dispersed in the asphalt, under high temperature, a stabilizer cross-links the polymers and the asphalt, forming a polymer network structure, significantly improving the high and low temperature properties of the asphalt. However, a challenging problem exists in the production of polymer-modified asphalt: after a certain development time, the modified asphalt meets the required performance specifications, but a certain number of active sites still exist in the polymer. The cross-linking reaction does not automatically stop. During subsequent storage and transportation, the polymer continues to cross-link, causing the asphalt viscosity to increase further, and in severe cases, even turning into a gel. The asphalt, losing its fluidity, will clog storage tanks or transport vehicles, unable to be discharged, causing serious production accidents.

[0003] CN1171953C discloses a production process for polymer-modified asphalt. This method involves first refining and dispersing the modifier under strong shear, and then adding a stabilizer to allow the modifier and asphalt to undergo chemical cross-linking, forming a stable three-dimensional network structure. However, this method cannot guarantee that the cross-linking reaction will proceed fully, and the viscosity will increase after long-term storage.

[0004] CN102453333B discloses a method for preparing polymer-modified asphalt. This method involves ultrasonic dispersion during the mixing process, followed by the addition of a stabilizer to carry out a crosslinking reaction. This method can accelerate the polymer dispersion process, but it still cannot fundamentally control the degree of crosslinking reaction in the polymer. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for preparing polymer-modified asphalt, which solves the problem of continued cross-linking of the polymer and further increase in asphalt viscosity. This method allows the performance of polymer-modified asphalt to remain at the desired performance levels, achieving controllable modification.

[0006] This invention provides a method for preparing polymer-modified asphalt, comprising:

[0007] (1) Mix the molten base asphalt with the compatibilizer, and then perform the first heating;

[0008] (2) Mix the material after the first heating with the polymer and crosslinking accelerator, and then shear it;

[0009] (3) The material after shearing in step (2) is heated a second time and stirred to carry out the development reaction;

[0010] (4) After the development reaction is completed, the temperature is lowered, a crosslinking terminator is added, and the mixture is stirred to obtain polymer-modified asphalt;

[0011] The crosslinking terminator is a combination of hindered piperidine derivatives and benzotriazole compounds.

[0012] Furthermore, the mass ratio of the base asphalt, compatibilizer, polymer, crosslinking accelerator, and crosslinking terminator is 100:2-6:2-8:0.05-0.5:0.05-0.2.

[0013] Further, in step (1), the base asphalt refers to natural asphalt or petroleum asphalt, tar asphalt, etc. obtained by refining and processing, and the penetration of the base asphalt at 25°C is 60~2001 / 10mm.

[0014] Furthermore, in step (1), the base asphalt is heated to a molten state at a temperature of 135–160°C.

[0015] Further, in step (1), the compatibilizer is one or a mixture of several of the following: reduced-strength extraction oil, furfural refined extraction oil, phenol refined extraction oil, and catalytic cracking slurry oil.

[0016] Further, in step (1), the first heating is to heat the temperature to 140-180°C.

[0017] Further, in step (2), the polymer is a thermoplastic rubber polymer, more preferably a thermoplastic rubber polymer containing a conjugated diene structure, and even more preferably SBS.

[0018] Furthermore, in step (2), the crosslinking promoter is a polyfunctional amine with the following structural formula:

[0019]

[0020] Further, in step (2), the shearing conditions are: shearing speed of 2000-5000 r / min and shearing time of 10-50 min.

[0021] Further, in step (3), the second heating is to heat the temperature to 185-220°C. Preferably, the temperature after the second heating is 10-50°C higher than the temperature after the first heating.

[0022] Furthermore, in step (3), the developmental reaction time is 30 to 200 minutes.

[0023] Furthermore, in step (4), the cooling is to cool down to 140-160°C.

[0024] Furthermore, the mass ratio of the hindered piperidine derivative to the benzotriazole compound is 0.1 to 5:1, preferably 0.25 to 4:1.

[0025] Further, the hindered piperidine derivative is at least one of 2-ethyl-2-(4-hydroxy-3,5-tert-butylbenzyl)malonate bis(1,2,2,6,6-pentamethyl-4-hydroxypiperidine), sebacate bis(1,2,2,6,6-pentamethyl-4-hydroxypiperidine), and tris(1,2,2,6,6-pentamethyl-4-hydroxypiperidine) phosphite.

[0026] Further, the benzotriazole compound is at least one of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, and 2-(2'-hydroxy-3'-cumyl-5'-tert-octylphenyl)benzotriazole.

[0027] Further, a crosslinking terminator is added, and the stirring time is 10 to 50 minutes.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) The reaction-controllable polymer-modified asphalt of the present invention incorporates a reaction control agent, which can promptly remove the remaining double bonds in the polymer (such as SBS), stop the polymer from further cross-linking, maintain the viscosity of the asphalt, and precisely control the performance of the modified asphalt.

[0030] (2) The reaction-controlled polymer-modified asphalt of the present invention has a longer-lasting high and low temperature performance because it removes the remaining unstable double bonds in the polymer, slows down the degradation rate of the polymer, and thus slows down the performance decay rate of the polymer-modified asphalt.

[0031] (3) The reaction control agents used include hindered piperidine derivatives and benzotriazole compounds, which have a very good synergistic effect and can significantly improve the reaction control ability. Detailed Implementation

[0032] The technical solution of the present invention will be described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] Base asphalt with a penetration of 801 / 10mm at 25℃ was melted at 155℃. A compatibilizer and reduced-strength extract oil were added, and a mixture was obtained under stirring. The mixture was further heated to 160℃, and SBS polymer and a crosslinking accelerator (polyfunctional amine) were added. The mixture was then subjected to constant-temperature shearing in a high-speed shear emulsifier for 30 minutes at a shearing speed of 3000 r / min. The temperature was then raised to 195℃ and stirred for 120 minutes. The mixture was then cooled to 155℃, and crosslinking terminator 1 was added. Stirring was continued for 40 minutes to obtain polymer-modified asphalt. The amounts of each raw material are shown in Table 1, and the formulation of the crosslinking terminator is shown in Table 2.

[0035] Example 2

[0036] Base asphalt with a penetration of 1021 / 10mm at 25℃ was melted at 145℃, and furfural refined extract oil was added as a compatibilizer. A mixture was obtained under stirring. The mixture was further heated to 150℃, and SBS polymer and polyfunctional amine crosslinking accelerator were added. The mixture was then subjected to constant-temperature shearing in a high-speed shear emulsifier for 20 minutes at a shearing speed of 4000 r / min. The temperature was then raised to 190℃ and stirred for 180 minutes. The temperature was then lowered to 140℃, and crosslinking terminator 2 was added. Stirring was continued for another 20 minutes to obtain polymer-modified asphalt. The amounts of each raw material are shown in Table 1, and the crosslinking terminator formulation is shown in Table 2.

[0037] Example 3

[0038] Base asphalt with a penetration of 145 1 / 10 mm at 25℃ was melted by heating at 145℃. Phenolic refined extract oil, a compatibilizer, was added, and a mixture was obtained under stirring. The mixture was then heated to 175℃, and SBS polymer and polyfunctional amine crosslinking accelerator were added. The mixture was then subjected to constant-temperature shearing in a high-speed shear emulsifier for 40 minutes at a shearing speed of 5000 r / min. The temperature was then raised to 185℃ and stirred for 100 minutes. The temperature was then lowered to 160℃, and crosslinking terminator 3 was added. Stirring was continued for 30 minutes to obtain polymer-modified asphalt. The amounts of each raw material are shown in Table 1, and the crosslinking terminator formulation is shown in Table 2.

[0039] Example 4

[0040] Base asphalt with a penetration of 180 1 / 10 mm at 25℃ was melted at 135℃, and a compatibilizer and catalytic cracking slurry were added. A mixture was obtained under stirring. The mixture was further heated to 140℃, and polymer SBS and crosslinking accelerator polyfunctional amine were added. The mixture was then subjected to isothermal shearing in a high-speed shear emulsifier for 50 min at a shearing speed of 4000 r / min. The temperature was then raised to 210℃ and stirred for 60 min. The temperature was then lowered to 140℃, and crosslinking terminator 4 was added. Stirring was continued for another 50 min to obtain a storage-stable polymer-modified asphalt. The amounts of each raw material are shown in Table 1, and the crosslinking terminator formulation is shown in Table 2.

[0041] Example 5

[0042] Base asphalt with a penetration of 921 / 10mm at 25℃ was melted at 155℃. A compatibilizer and reduced-strength extract oil were added, and a mixture was obtained under stirring. The mixture was further heated to 180℃, and SBS polymer and a crosslinking accelerator (polyfunctional amine) were added. The mixture was then subjected to constant-temperature shearing in a high-speed shear emulsifier for 20 minutes at a shearing speed of 3000 r / min. The mixture was then heated to 180℃ and stirred for 80 minutes. After cooling to 150℃, crosslinking terminator 5 was added, and stirring continued for 20 minutes to obtain polymer-modified asphalt. The amounts of each raw material are shown in Table 1, and the crosslinking terminator formulation is shown in Table 2.

[0043] Example 6

[0044] The base asphalt with a penetration of 1131 / 10 mm at 25℃ was melted by heating at 160℃, and phenol-refined extract oil was added as a compatibilizer. A mixture was obtained under stirring. The mixture was then heated to 170℃, and SBS polymer and polyfunctional amine crosslinking accelerator were added. The mixture was subjected to constant-temperature shearing in a high-speed shear emulsifier for 40 min at a shearing speed of 2000 rpm. The temperature was then raised to 185℃ and stirred for 140 min. The mixture was then cooled to 155℃, and crosslinking terminator 6 was added. Stirring was continued for 30 min to obtain a storage-stable polymer-modified asphalt. The amounts of each raw material are shown in Table 1, and the formulation of the crosslinking terminator is shown in Table 2.

[0045] Table 1

[0046]

[0047] Table 2

[0048]

[0049]

[0050] Comparative Example 1

[0051] Compared with Example 1, the difference is that no crosslinking promoter and crosslinking terminator are added, while the amount of other raw materials and preparation conditions remain the same as in Example 1.

[0052] Comparative Example 2

[0053] Compared with Example 1, the difference is that only an equal mass of crosslinking promoter is added, and no crosslinking terminator is added. The amounts of other raw materials and preparation conditions are the same as in Example 1.

[0054] Comparative Example 3

[0055] Compared with Example 1, the difference is that the crosslinking terminator added is only an equal mass of sebacic acid bis(1,2,2,6,6-pentamethyl-4-hydroxypiperidine) ester, while the amounts of other raw materials and preparation conditions are the same as in Example 1.

[0056] Comparative Example 4

[0057] Compared with Example 1, the difference is that the crosslinking accelerator is replaced with an equal mass of sulfur accelerator, while the amounts of other raw materials and preparation conditions remain the same as in Example 1.

[0058] Test method:

[0059] Storage tests were conducted on polymer-modified bitumen from Examples 1-6 and Comparative Examples 1-4. The test conditions were set as follows: storage temperature 163℃, storage time 7 days, and penetration at 25℃ and viscosity at 135℃ were measured according to JTG E20-2011. The test results are shown in Table 3.

[0060] Table 3

[0061]

[0062] The specific embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing polymer-modified asphalt, characterized in that, include: (1) Mix the molten base asphalt with the compatibilizer, and then perform the first heating; (2) Mix the material after the first heating with the polymer and crosslinking accelerator, and then shear; (3) The material after shearing in step (2) is heated a second time and stirred to carry out the development reaction; (4) After the development reaction is completed, the temperature is lowered, a crosslinking terminator is added, and the mixture is stirred to obtain polymer-modified asphalt; The crosslinking terminator is a combination of hindered piperidine derivatives and benzotriazole compounds; The crosslinking accelerator is a multifunctional amine with the following structural formula: 。 2. The method according to claim 1, characterized in that, The mass ratio of the base asphalt, compatibilizer, polymer, crosslinking accelerator, and crosslinking terminator is 100:2~6:2~8:0.05~0.5:0.05~0.

2.

3. The method according to claim 1, characterized in that, In step (1), the penetration of the base asphalt at 25°C is 60~200 1 / 10mm; the temperature at which the base asphalt is heated to the molten state is 135~160°C.

4. The method according to claim 1, characterized in that, In step (1), the compatibilizer is one or a mixture of several of the following: reduced-temperature four-line extracted oil, furfural refined extracted oil, phenol refined extracted oil, and catalytic cracking slurry oil.

5. The method according to claim 1, characterized in that, In step (1), the first heating is to heat the temperature to 140~180℃.

6. The method according to claim 1, characterized in that, In step (2), the polymer is a thermoplastic rubber polymer.

7. The method according to claim 6, characterized in that, In step (2), the polymer is a thermoplastic rubber polymer containing a conjugated diene structure.

8. The method according to claim 6, characterized in that, In step (2), the polymer is SBS.

9. The method according to claim 1, characterized in that, In step (2), the shearing conditions are: shearing speed of 2000~5000 r / min and shearing time of 10~50 min.

10. The method according to claim 1, characterized in that, In step (3), the second heating is to heat the temperature to 185~220℃.

11. The method according to claim 10, characterized in that, In step (3), the temperature after the second heating is 10~50℃ higher than the temperature after the first heating.

12. The method according to claim 1, characterized in that, In step (3), the developmental reaction takes 30 to 200 minutes.

13. The method according to claim 1, characterized in that, In step (4), the cooling is to cool down to 140~160℃.

14. The method according to claim 1, characterized in that, The mass ratio of the hindered piperidine derivative to the benzotriazole compound is 0.1 to 5:

1.

15. The method according to claim 14, characterized in that, The mass ratio of the hindered piperidine derivative to the benzotriazole compound is 0.25 to 4:

1.

16. The method according to claim 1 or 14, characterized in that, The hindered piperidine derivative is at least one selected from bis(1,2,2,6,6-pentamethyl-4-hydroxypiperidine) ester of 2-ethyl-2-(4-hydroxy-3,5-tert-butylbenzyl)malonate, bis(1,2,2,6,6-pentamethyl-4-hydroxypiperidine) sebacate, and tris(1,2,2,6,6-pentamethyl-4-hydroxypiperidine) phosphite; and / or, The benzotriazole compound is at least one of 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, and 2-(2'-hydroxy-3'-cumyl-5'-tert-octylphenyl)benzotriazole.

17. The method according to claim 1, characterized in that, Add the crosslinking terminator, and stir for 10-50 minutes.

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