Desulfurized-rubber-modified asphalt and preparation method therefor

Abstract

Disclosed in the present invention are a desulfurized-rubber-modified asphalt and a preparation method therefor. The asphalt of the present invention comprises, in parts by mass, 100 parts of petroleum asphalt, 25-35 parts of desulfurized rubber powder, 0.2-2 parts of an oxime-sulfonate-based modifier, and 0.5-3 parts of a modified artificial zeolite, wherein starting materials of the desulfurized rubber powder comprise waste rubber powder, calcium nitrate, aniline, 2,5-benzothiazole dithiol, p‑tolylmagnesium bromide, diphenyl sulfoxide, and trimethylchlorosilane in a mass ratio of 80-100:10-20:20-30:5-10:5-6:1:3-4. Further disclosed in the present invention is a specific preparation method for the desulfurized rubber powder. The asphalt of the present invention has simple components, improved properties and low blending temperature and is more convenient to use.

Description

A desulfurized rubber-modified asphalt and its preparation method Technical Field

[0001] This invention belongs to the field of polymer materials and relates to a method for preparing asphalt materials, particularly a desulfurized rubber-modified asphalt and its preparation method. Background Technology

[0002] Waste tires are recycled and crushed to produce rubber powder, which is then used to modify asphalt to prepare rubberized asphalt. This process not only improves the performance of asphalt but also alleviates the environmental problems caused by waste tires, making it a commonly used technology in asphalt production. However, if undesulfurized rubber powder is used in this process, agglomeration is likely to occur, leading to excessively high viscosity of the rubberized asphalt, difficulty in mixing, and increased mixing time and temperature. It has been found that using desulfurized rubber powder can improve agglomeration. This is because the network structure of the rubber powder is disrupted after desulfurization, reducing the resistance to asphalt molecules diffusing into the rubber powder network, increasing the contact area with the asphalt, and making swelling more likely.

[0003] To fully utilize the modifying effect of rubber powder on asphalt, other substances are used to improve the interfacial interaction between rubber powder and asphalt, thereby enhancing the stability of waste rubber powder in asphalt. For example, Chinese patent application No. 201010579826.X discloses one or more modifiers, including sulfur, polyethylene terephthalate, N-cyclohexyl-2-benzothiazole sulfenamide, and morpholine disulfide. This application requires a high-speed shear emulsifier to assist the reaction, making the operating conditions quite demanding. Furthermore, to further improve the various properties of asphalt, multiple raw materials such as plasticizers, dispersants, accelerators, and anti-aging agents are often added. This results in an overly complex mixing process, causing inconvenience for construction workers.

[0004] Therefore, it is necessary to study a desulfurized rubber-modified asphalt that has simple components, is easy to construct, and has good performance. Technical issues

[0005] This invention provides a desulfurized rubber-modified asphalt and its preparation method, aiming to simplify the components of desulfurized rubber-modified asphalt, reduce mixing temperature and construction difficulty, and study the components of desulfurized rubber-modified asphalt and the desulfurized rubber powder used. Solution

[0006] To achieve the above objectives, the present invention provides a desulfurized rubber modified asphalt, the key being that, by mass parts, the asphalt comprises 100 parts of petroleum asphalt, 25 to 35 parts of desulfurized rubber powder, 0.2 to 2 parts of oxime sulfonate modifier, and 0.5 to 3 parts of modified artificial zeolite.

[0007] The raw materials for preparing the above-mentioned desulfurized rubber powder include waste rubber powder, calcium nitrate, aniline, 2,5-benzothiazole dithiol, p-methylphenyl magnesium bromide, diphenyl sulfoxide and trimethylchlorosilane in a mass ratio of 80-100:10-20:20-30:5-10:5-6:1:3-4.

[0008] The above-mentioned desulfurized rubber powder is prepared by:

[0009] Add 5 to 6 parts of 4-methylphenyl magnesium bromide and 1 part of diphenyl sulfoxide to an inert organic solvent. Control the temperature at 12 ℃ to 32 ℃. Add 3 to 4 parts of p-trimethylchlorosilane dropwise. After reacting for 2 to 4 hours, quench the reaction with water. Adjust the pH value to 1 to 2. After separation, retain the aqueous phase and concentrate it.

[0010] Add 10 to 20 parts of calcium nitrate to the concentrated aqueous phase and stir until the calcium nitrate is fully dissolved to prepare a calcium nitrate solution.

[0011] Mix 80 to 100 parts of waste rubber powder, 20 to 30 parts of aniline and the above calcium nitrate solution, heat to 130 ℃ to 135 ℃, continue stirring and react for 1 h to 2 h, then add 5 to 10 parts of 2,5-benzothiazole dithiol, and continue stirring for 0.5 h to 1 h.

[0012] After filtration, washing with water, and drying, the above-mentioned desulfurized rubber powder is obtained.

[0013] Preferably, the stirring rate for the above-mentioned mixing is 10 r / min to 15 r / min; and the drying temperature for the above-mentioned drying is 45 ℃ to 60 ℃.

[0014] Specifically, the aforementioned oxime sulfonate modifier is prepared by reacting 2,3-butanedione dioxime and p-toluenesulfonyl chloride under the action of an acid-binding agent, followed by crystallization, filtration, and drying.

[0015] Preferably, the acid-binding agent mentioned above is either pyridine or triethylamine.

[0016] Furthermore, the preparation method of the above-mentioned modified artificial zeolite is as follows: cellulose acetate and artificial zeolite are added to water, heated to 80 ℃~110 ℃, lauric acid is added, stirring is continued and the temperature is raised to 100 ℃~115 ℃, the reaction is kept at this temperature for 1 h~2 h, and then filtered and dried to obtain the above-mentioned modified artificial zeolite; the mass ratio of the above-mentioned cellulose acetate, artificial zeolite and lauric acid is 1:1~1.5:0.3~0.8.

[0017] A method for preparing desulfurized rubber-modified asphalt, used to prepare the aforementioned modified asphalt, is characterized by the following specific steps in the preparation method:

[0018] Petroleum asphalt is heated to a molten state, modified artificial zeolite and desulfurized rubber powder are added, the temperature is raised to 120 ℃~135 ℃, and stirring is continued to allow it to swell fully. Oxime sulfonate modifier is added, and stirring is carried out to prepare the modified asphalt. Beneficial effects

[0019] In summary, the asphalt of this invention utilizes desulfurized rubber produced through a special process. During desulfurization, this process not only more effectively disrupts disulfide bonds and better protects the carbon-carbon backbone, but also introduces abundant oxygen-containing groups and side chains providing active sulfur elements into the backbone. This significantly improves the interfacial bonding between the rubber powder and the asphalt, enhancing their compatibility. Therefore, this invention eliminates the need for accelerators, dispersants, and other auxiliary materials in its composition.

[0020] The modified zeolite added in this invention can serve as a novel warm mix agent, lowering the mixing temperature. Zeolite has numerous channels and pores distributed on its surface. The presence of these channels and pores allows zeolite to adsorb and retain moisture, enabling it to continuously foam as an asphalt warm mix agent. However, synthetic zeolite is not as effective as natural zeolite, which is more expensive. This invention places synthetic zeolite in a water-soluble cellulose solution, filling the pores of the zeolite with water-soluble cellulose. Lauric acid is then added to modify the cellulose into insoluble cellulose particles, expanding the channel capacity of the zeolite and improving the water adsorption and retention capacity of the synthetic zeolite warm mix agent. Furthermore, the insoluble cellulose also helps to improve the strength and toughness of asphalt.

[0021] The modifier used in this invention does not require harsh reaction temperature conditions, and ordinary light can help the modifier to work, so that the modification can be completed during the mixing process.

[0022] Meanwhile, the modifier and desulfurized rubber powder used in this invention also help improve the anti-aging properties of asphalt, manifested in a smaller decrease in ductility and strength before and after aging treatment. Therefore, this invention can reduce or eliminate the use of antioxidants. The best embodiment of the present invention

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Examples 1 to 3

[0025] In this embodiment, desulfurized rubber powder is prepared. The specific process parameters and material ratios are shown in Table 1.

[0026] The specific preparation process of desulfurized rubber powder is as follows:

[0027] S1. Preparation of calcium nitrate solution

[0028] Add 5 to 6 parts of 4-methylphenyl magnesium bromide and 1 part of diphenyl sulfoxide to an inert organic solvent. Control the temperature at 12 ℃ to 32 ℃. Add 3 to 4 parts of p-trimethylchlorosilane dropwise. After reacting for 2 to 4 hours, quench the reaction with water. Adjust the pH value to 1 to 2. After separation, retain the aqueous phase and concentrate it to about 1 / 2 of the original volume.

[0029] Add 10 to 20 parts of calcium nitrate to the aqueous phase and stir until the calcium nitrate is fully dissolved to prepare a calcium nitrate solution.

[0030] S2, Desulfurization process of rubber powder:

[0031] Mix 80-100 parts of rubber powder, 20-30 parts of aniline and the above calcium nitrate solution at a stirring rate of 10-15 r / min, heat to 130-135 ℃, continue stirring and react for 1-2 h, then add 5-10 parts of 2,5-benzothiazole dithiol and continue stirring for 0.5-1 h.

[0032] S3, Drying:

[0033] After filtration, washing with water, and drying, the desulfurized rubber powder is obtained. According to Examples 1 to 3, desulfurized rubber powder samples 1 to 3 are prepared for later use.

[0034] Table 1: Specific process parameters and material usage for the preparation of desulfurized rubber powder

[0035]

[0036] Continued from Table 1: Specific process parameters and material usage for the preparation of desulfurized rubber powder

[0037]

[0038] Examples 4 to 6

[0039] In this embodiment, modified artificial zeolite was prepared. The specific process parameters and material ratios are shown in Table 2.

[0040] The specific preparation process of modified synthetic zeolite is as follows:

[0041] Cellulose acetate and artificial zeolite were added to water and heated to 80 ℃~110 ℃. Lauric acid was added, and the mixture was stirred and heated to 100 ℃~115 ℃. After reacting at this temperature for 1 h~2 h, the mixture was filtered and dried to obtain the modified artificial zeolite. The mass ratio of cellulose acetate, artificial zeolite and lauric acid was 1:1~1.5:0.3~0.8.

[0042] According to Examples 4 to 6, modified artificial zeolite samples 1 to 3 were prepared respectively for later use.

[0043] Table 2: Specific process parameters and material usage for the preparation of modified synthetic zeolite

[0044]

[0045] Examples 7 to 9

[0046] In this embodiment, the oxime sulfonate modifier was prepared by reacting 2,3-butanedione dioxime and p-toluenesulfonyl chloride in the presence of pyridine or triethylamine, followed by crystallization, filtration, and drying. Specific process parameters and material ratios are shown in Table 3.

[0047] The structural formula of the prepared oxime sulfonate modifier is:

[0048] .

[0049] Table 3: Specific process parameters and material usage for the preparation of oxime sulfonate modifiers

[0050]

[0051] According to Examples 7 to 9, modifier samples 1 to 3 were prepared respectively for later use.

[0052] Examples 10 to 18

[0053] The specific steps for preparing desulfurized rubber-modified asphalt in this embodiment are as follows:

[0054] Weigh out 100 parts of petroleum asphalt, 25 to 35 parts of desulfurized rubber powder, 0.2 to 2 parts of oxime sulfonate modifier, and 0.5 to 3 parts of modified artificial zeolite by weight.

[0055] Petroleum asphalt is heated to a molten state, and modified artificial zeolite and desulfurized rubber powder are added and stirred. The temperature is raised to 120 ℃~135 ℃, and stirring is continued to allow it to swell fully. Oxime sulfonate modifiers are added and stirred to allow it to develop, thus preparing desulfurized rubber modified asphalt.

[0056] Table 4: Specific process parameters and material usage for the preparation of desulfurized rubber-modified asphalt

[0057]

[0058] In Table 4, the purchased oxime sulfonate compound 1 is 2,3-butanedione bis[O-(butylsulfonyl)oxime, with the following structural formula:

[0059] ;

[0060] The purchased oxime sulfonate compound 2 is 4-[O-[(4-methoxyphenyl)sulfonyl]oxime]-2,6-dimethyl-2,5-cyclohexadien-1,4-dione, with the following structural formula:

[0061] ;

[0062] The purchased oxime sulfonate compound 3 is 4,5-diazafluorene-9-one O-p-toluenesulfonyl oxime, with the following structural formula:

[0063] .

[0064] According to Examples 10 to 18, asphalt samples 1 to 9 were prepared respectively.

[0065] Comparative Example 1

[0066] The implementation method of this comparative example is the same as that of Example 10, except that the desulfurized rubber powder sample 1 prepared in this invention is not used, but rubber powder treated with strong acid desulfurization is used. The specific process is as follows:

[0067] S1. Preparation of desulfurizing agent

[0068] Mix 10 parts toluene and 2 parts acetic acid, add 2 parts ferric chloride and 2 parts hydrochloric acid (30% mass concentration) to prepare a ferric chloride solution, and then mix well for later use.

[0069] S2, Desulfurization process of rubber powder:

[0070] Mix 10 parts of rubber powder with 100 parts of the desulfurizing agent prepared above, stir thoroughly, and carry out the desulfurization reaction at 50°C for 8 hours;

[0071] S3, Drying:

[0072] After filtration and washing with water, and drying, desulfurized rubber powder reference standard 1 is obtained for later use.

[0073] Asphalt reference standard 1 was prepared by using desulfurized rubber powder reference standard 1 according to the material ratio of Example 10, controlling the temperature according to the actual process conditions, and observing the state of asphalt.

[0074] Comparative Example 2

[0075] The implementation method of this comparative example is the same as that of Example 10, except that the desulfurized rubber powder sample 1 prepared by this invention is not used. Instead, the preparation process of the desulfurized rubber powder is studied. The specific process is as follows:

[0076] S1. Preparation of calcium nitrate solution

[0077] Add 35 parts of calcium nitrate to 200 parts of water and stir until the calcium nitrate is fully dissolved to prepare a calcium nitrate solution.

[0078] S2, Desulfurization process of rubber powder:

[0079] 90 parts of rubber powder, 25 parts of aniline and the above-mentioned calcium nitrate solution were stirred and mixed. The subsequent preparation process was the same as in Example 1 to prepare desulfurized rubber powder reference standard 2 for later use.

[0080] Asphalt reference standard 2 was prepared by using the material ratio of desulfurized rubber powder reference standard 2 according to Example 10, controlling the temperature according to the actual process conditions, and observing the state of asphalt.

[0081] Comparative Example 3

[0082] The implementation method of this comparative example is the same as that of Example 10, except that the modifier sample 1 prepared by the present invention is not used, but 5 parts of hydrogen peroxide are used to prepare asphalt control sample 3.

[0083] Comparative Example 4

[0084] The implementation method of this comparative example is the same as that of Example 10, except that the modifier sample 1 prepared by the present invention is not used. Instead, 5 parts of silane coupling agent (vinyltris(2-methoxyethoxy)silane is used in this comparative example) are used to prepare asphalt reference standard 4.

[0085] Comparative Example 5

[0086] The implementation method of this comparative example is the same as that of Example 10, except that the modified artificial zeolite 1 prepared in this invention is not used. Instead, ordinary artificial zeolite of the same mass is used, and the mixing temperature is controlled according to the actual situation during mixing to prepare asphalt control product 5.

[0087] Analysis and Testing

[0088] 1. Research on desulfurized rubber powder

[0089] (1) Elemental analysis

[0090] Elemental analysis was performed on waste rubber powder (rubber powder before desulfurization), desulfurized rubber powder samples, and reference standards. The results are shown in Table 5.

[0091] Table 5: Elemental Analysis Results of Adhesive Powder

[0092]

[0093] As shown in Table 5, the sulfur (S) content in the rubber powder did not decrease before and after desulfurization. This is because the desulfurization process does not remove sulfur, but rather breaks disulfide bonds. Simultaneously, 2,5-benzothiazole dithiol is introduced into the desulfurization process, providing abundant carbon (C) and sulfur (S) elements and increasing their ratio. However, regarding the increase in oxygen (O), since 2,5-benzothiazole dithiol does not contain oxygen, the added O element originates from the desulfurization process.

[0094] (2) Crosslinking density analysis

[0095] The crosslinking density of waste rubber powder, desulfurized rubber powder samples, and control samples was tested using the equilibrium swelling method. The results are shown in Table 6.

[0096] (3) Contact angle analysis

[0097] The contact angles of waste rubber powder, desulfurized rubber powder samples, and control samples were tested using a contact angle meter. The results are shown in Table 6.

[0098] Table 6: Analysis Results of Crosslinking Density and Contact Angle of Adhesive Powder

[0099]

[0100] As shown in Table 6, the crosslinking density and contact angle of the desulfurized rubber powder in this embodiment are significantly reduced, indicating that the network structure of the rubber powder is fully destroyed and the hydrophilicity is greatly improved. This is because the calcium nitrate oxidation method used in this invention for desulfurization of the rubber powder not only breaks the disulfide bonds but also introduces oxygen-containing groups, increasing the hydrophilicity of the rubber powder surface. Simultaneously, the 2,5-benzothiazole dithiol introduced in this invention provides active sulfur atoms, forming covalent bonds with the hydroxyl or carboxyl groups on the rubber powder surface. This not only enhances the surface activity of the rubber powder but also improves its compatibility with the polymer matrix. In contrast, the crosslinking degree and contact angle of the desulfurized rubber powder control 2 are still very high, indicating that the desulfurization process in Comparative Example 2 is not sufficient. This is because calcium nitrate is difficult to miscible with the rubber powder in the organic phase. This invention uses 4-methylphenyl magnesium bromide and p-trimethylchlorosilane through a simple reaction to prepare an onium salt solution with catalytic function, increasing the contact area between calcium nitrate and the rubber powder, thereby improving the desulfurization efficiency. This onium salt itself does not participate in the oxidation reaction, so the catalytic efficiency is even higher.

[0101] 2. Asphalt Performance Analysis

[0102] Asphalt samples and reference standards were taken. The test data are shown in Table 7 according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTJ 052-2000).

[0103] Table 7: Test Data of Asphalt Samples

[0104]

[0105] As shown in Table 7, the asphalt samples prepared by this invention exhibit high softening point, viscosity, and ductility. This is likely because the desulfurized rubber powder used in this invention primarily breaks disulfide bonds while minimizing main chain damage, and new side chains are introduced into the main chain. Theoretically, adding side chains increases the network structure, but the side chains introduced in this invention provide reactive sulfur elements, facilitating the diffusion and penetration of small molecule asphalt, thus providing better high and low temperature performance for the asphalt. Increased ductility indicates enhanced plasticity of the asphalt. The changes in ductility, tensile strength, and elastic recovery before and after aging are lower in this invention, indicating that the anti-aging ability of this invention is also improved. This is because the modifier used in this invention has special properties, requiring no excessively high temperatures during crosslinking and reacting rapidly under normal operation. In Examples 16-18, three commercially available oxime sulfonate compounds were selected. The asphalt prepared using these compounds showed performance similar to that of the self-made modifier, maintaining good ductility, tensile strength, and elastic recovery after aging, although the decrease in performance indicators after aging was slightly greater.

Claims

1. A desulfurized rubber-modified asphalt, characterized in that, By weight, the asphalt comprises 100 parts petroleum asphalt, 25 to 35 parts desulfurized rubber powder, 0.2 to 2 parts oxime sulfonate modifier, and 0.5 to 3 parts modified synthetic zeolite. The raw materials for preparing the desulfurized rubber powder include waste rubber powder, calcium nitrate, aniline, 2,5-benzothiazole dithiol, p-methylphenyl magnesium bromide, diphenyl sulfoxide and trimethylchlorosilane in a mass ratio of 80-100:10-20:20-30:5-10:5-6:1:3-4. The preparation method of the desulfurized rubber powder is as follows: Add 5 to 6 parts of 4-methylphenyl magnesium bromide and 1 part of diphenyl sulfoxide to an inert organic solvent. Control the temperature at 12℃ to 32℃. Add 3 to 4 parts of p-trimethylchlorosilane dropwise. After reacting for 2 to 4 hours, quench the reaction with water. Adjust the pH value to 1 to 2. After separation, retain the aqueous phase and concentrate it. Add 10 to 20 parts of calcium nitrate to the concentrated aqueous phase and stir until the calcium nitrate is fully dissolved to prepare a calcium nitrate solution. Mix 80 to 100 parts of waste rubber powder, 20 to 30 parts of aniline and the calcium nitrate solution, heat to 130 ℃ to 135 ℃, continue stirring and react for 1 to 2 hours, then add 5 to 10 parts of 2,5-benzothiazole dithiol, and continue stirring for 0.5 to 1 hour. After filtration, washing with water, and drying, the desulfurized rubber powder is obtained. The modified artificial zeolite is prepared by adding cellulose acetate and artificial zeolite to water, heating to 80 ℃~110 ℃, adding lauric acid, continuing to stir and raising the temperature to 100 ℃~115 ℃, keeping the reaction at this temperature for 1 h~2 h, filtering and drying to obtain the modified artificial zeolite; the mass ratio of cellulose acetate, artificial zeolite and lauric acid is 1:1~1.5:0.3~0.

8.

2. The desulfurized rubber-modified asphalt according to claim 1, characterized in that, The stirring rate for mixing is 10 r / min to 15 r / min; the drying temperature is 45℃ to 60℃.

3. The desulfurized rubber-modified asphalt according to claim 1, characterized in that, The oxime sulfonate modifier is prepared by reacting 2,3-butanedione dioxime and p-toluenesulfonyl chloride under the action of an acid-binding agent, followed by crystallization, filtration, and drying.

4. The desulfurized rubber-modified asphalt according to claim 3, characterized in that, The acid-binding agent is either pyridine or triethylamine.

5. A method for preparing desulfurized rubber-modified asphalt according to any one of claims 1-4, characterized in that, The specific steps of the preparation method are as follows: Petroleum asphalt is heated to a molten state, modified artificial zeolite and desulfurized rubber powder are added, the temperature is raised to 120 ℃~135 ℃, and stirring is continued to allow it to swell fully. Oxime sulfonate modifier is added, and stirring is carried out to prepare the modified asphalt.

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