A kind of desulfurized rubber modified asphalt and preparation method thereof

Abstract

The invention discloses a desulfurized rubber modified asphalt and a preparation method thereof. The asphalt of the invention comprises, by weight, 100 parts of petroleum asphalt, 25 to 35 parts of desulfurized rubber powder, 0.2 to 2 parts of an oxime sulfonate modifier, and 0.5 to 3 parts of a modified artificial zeolite; wherein the raw materials of the desulfurized rubber powder comprise waste rubber powder, calcium nitrate, aniline, 2,5-benzothiazole dithiol, p-methylphenyl magnesium bromide, diphenyl sulfoxide, and trimethylchlorosilane in a weight ratio of 80 to 100:10 to 20:20 to 30:5 to 10:5 to 6:1:3 to 4; the invention also discloses a specific preparation method of the desulfurized rubber powder; the asphalt of the invention has simple components, not only various properties are improved, but also the mixing temperature is low and the use is more convenient.

Description

Technical Field

[0001] The invention belongs to the field of polymer materials and relates to a preparation method of an asphalt material, in particular to a desulfurized rubber modified asphalt and a preparation method thereof. Background Art

[0002] Recycling and crushing waste tires to make rubber powder for asphalt modification to prepare rubber asphalt can not only improve the performance of asphalt, but also alleviate the environmental problems caused by waste tires. It is a commonly used technology in the field of asphalt production. If undesulfurized rubber powder is used in the above process, agglomeration is likely to occur, resulting in excessive viscosity of rubber asphalt, difficulty in stirring, and increased mixing time and temperature. People have found that the use of desulfurized rubber powder can improve the agglomeration phenomenon. This is because the network structure of the rubber powder is destroyed after desulfurization, the resistance of asphalt molecules to diffuse into the rubber powder network is reduced, and the contact area with asphalt is larger, which is more conducive to swelling.

[0003] In order to give full play to the modification effect of rubber powder on asphalt, other substances are also used to improve the interface between rubber powder and asphalt, thereby improving the stability of waste rubber powder in asphalt. For example, in the Chinese patent application with document number 201010579826.X, the modifier disclosed is one or more of sulfur, ethylene terephthalate, N-cyclohexyl-2-benzothiazole sulfonamide, dimorpholine disulfide and other substances. In this document, a high-speed shear emulsifier is required to assist the reaction, and the use conditions are relatively harsh. In addition, in order to further improve the various properties of asphalt, plasticizers, dispersants, promoters, anti-aging agents, dispersants and other raw materials are often added in a targeted manner. This makes the mixing process too complicated, which brings inconvenience to construction workers.

[0004] Therefore, it is necessary to study a desulfurized rubber modified asphalt with simple components, convenient construction and good performance. Summary of the invention

[0005] The purpose of the present invention is to simplify the components of desulfurized rubber modified asphalt, reduce the mixing temperature and construction difficulty, and study the components of desulfurized rubber modified asphalt and the desulfurized rubber powder used.

[0006] The technical solution adopted by the present invention provides a desulfurized rubber modified asphalt, the key is that, by weight, the above-mentioned asphalt includes 100 parts of petroleum asphalt, 25 parts to 35 parts of desulfurized rubber powder, 0.2 parts to 2 parts of oxime sulfonate modifier, and 0.5 parts 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-benzothiazoledithiol, p-methylphenylmagnesium bromide, diphenyl sulfoxide and trimethylsilyl chloride in a mass ratio of 80-100:10-20:20-30:5-10:5-6:1:3-4;

[0008] The preparation method of the above-mentioned desulfurized rubber powder is:

[0009] Add 5 to 6 parts of 4-methylphenylmagnesium bromide and 1 part of diphenyl sulfoxide to an inert organic solvent, control the temperature at 12°C to 32°C, dropwise add 3 to 4 parts of trimethylsilyl chloride, react for 2 to 4 hours, quench the reaction with water, adjust the pH value to 1 to 2, retain the aqueous phase after separation and concentrate;

[0010] Then, 10 to 20 parts of calcium nitrate are added to the concentrated aqueous phase, and stirred evenly until the calcium nitrate is fully dissolved to prepare a calcium nitrate solution;

[0011] 80 to 100 parts of waste rubber powder, 20 to 30 parts of aniline and the above calcium nitrate solution are stirred and mixed, heated to 130°C to 135°C, stirred and reacted for 1 to 2 hours, and then 5 to 10 parts of 2,5-benzothiazoledithiol are added and stirred for 0.5 to 1 hour.

[0012] The desulfurized rubber powder is obtained by filtering, washing with water and drying.

[0013] Preferably, the stirring rate of the stirring and mixing is 10 r / min to 15 r / min; and the drying temperature of the drying is 45°C to 60°C.

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

[0015] Preferably, the acid binding agent is any one of pyridine or triethylamine.

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

[0017] A method for preparing desulfurized rubber modified asphalt is used to prepare the modified asphalt. The key is that the specific steps of the preparation method are:

[0018] The petroleum asphalt is heated to a molten state, modified artificial zeolite and desulfurized rubber powder are added, the temperature is raised to 120°C to 135°C, stirring is continued to make it fully swollen, an oxime sulfonate modifier is added, stirring and developing, and the modified asphalt is prepared.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The asphalt of the present invention uses a desulfurized rubber with a special process. During the desulfurization process, not only the disulfide bonds are more specifically destroyed, the carbon-carbon main chain is better protected, but also abundant oxygen-containing groups and side chains providing active sulfur elements are introduced into the main chain, which fully improves the interface bonding performance between the rubber powder and the asphalt, and enhances the compatibility of the rubber powder and the asphalt. Therefore, the present invention omits auxiliary materials such as accelerators and dispersants in the components.

[0021] The modified zeolite added by the present invention can be used as a new warm-mixing agent to reduce the mixing temperature. Zeolite has a large number of channels and holes distributed on the surface. The presence of holes and channels enables zeolite to absorb and retain moisture, and can be used as a warm-mixing agent to continuously foam asphalt, while the effect of artificial zeolite is not as good as natural zeolite, but the cost of natural zeolite is higher. The present invention places artificial zeolite in a water-soluble cellulose solution, fills the holes of the zeolite with water-soluble cellulose, and then adds lauric acid to modify the cellulose to obtain insoluble cellulose particles, thereby expanding the channel capacity of the zeolite and improving the adsorption and water retention capacity of the artificial zeolite warm-mixing agent. In addition, insoluble cellulose is also beneficial to improving the strength and toughness of asphalt.

[0022] The reaction temperature conditions required for the modifier used in the present invention are not harsh, and general light is helpful for the action of the modifier, so that the modification can be completed during the mixing process of the present invention.

[0023] At the same time, the modifier and desulfurized rubber powder used in the present invention are also beneficial to improving the anti-aging performance of asphalt, which is manifested in that the reduction in ductility and strength before and after aging treatment becomes smaller. Therefore, the present invention can reduce or omit the use of antioxidants. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Embodiment 1 to Embodiment 3

[0026] In this example, desulfurized rubber powder was prepared. The specific process parameters and material ratios are shown in Table 1.

[0027] The specific preparation process of desulfurized rubber powder is:

[0028] S1. Preparation of calcium nitrate solution

[0029] Add 5 to 6 parts of 4-methylphenylmagnesium bromide and 1 part of diphenyl sulfoxide to an inert organic solvent, control the temperature at 12 ℃ to 32 ℃, dropwise add 3 to 4 parts of trimethylsilyl chloride, react for 2 h to 4 h, quench the reaction with water, adjust the pH value to 1 to 2, retain the aqueous phase after separation, and concentrate to about 1 / 2 of the original volume;

[0030] Then, 10 to 20 parts of calcium nitrate are added to the aqueous phase, and stirred evenly until the calcium nitrate is fully dissolved to prepare a calcium nitrate solution;

[0031] S2, rubber powder desulfurization process:

[0032] 80 to 100 parts of rubber powder, 20 to 30 parts of aniline and the above calcium nitrate solution are stirred and mixed at a stirring rate of 10 to 15 r / min, heated to 130 to 135°C, and stirred and reacted for 1 to 2 hours, then 5 to 10 parts of 2,5-benzothiazoledithiol are added and stirred for 0.5 to 1 hour;

[0033] S3, Drying:

[0034] The desulfurized rubber powder was filtered, washed with water and dried to obtain the desulfurized rubber powder. According to Example 1 to Example 3, desulfurized rubber powder samples 1 to 3 were prepared respectively for later use.

[0035] Table 1: Specific process parameters and material dosage of desulfurized rubber powder preparation process

[0036]

[0037] Table 1: Specific process parameters and material dosage of desulfurized rubber powder preparation process

[0038]

[0039] Embodiment 4 to Embodiment 6

[0040] In this example, modified artificial zeolite was prepared. The specific process parameters and material ratios are shown in Table 2.

[0041] The specific preparation process of modified artificial zeolite is:

[0042] Add cellulose acetate and artificial zeolite to water, heat to 80°C to 110°C, add lauric acid, continue stirring and heat to 100°C to 115°C, keep warm for 1 h to 2 h, filter and dry to prepare the modified artificial zeolite; the mass ratio of cellulose acetate, artificial zeolite and lauric acid is 1:1 to 1.5:0.3 to 0.8.

[0043] According to Example 4 to Example 6, modified artificial zeolite sample 1 to modified artificial zeolite sample 3 are prepared respectively and set aside.

[0044] Table 2: Specific process parameters and material dosage of modified artificial zeolite preparation process

[0045]

[0046] Embodiment 7 to Embodiment 9

[0047] In this embodiment, an oxime sulfonate modifier is prepared by reacting 2,3-butanedione dioxime and p-toluenesulfonyl chloride under the action of pyridine or triethylamine, followed by crystallization, filtration, and drying. For specific process parameters and material ratios, see Table 3.

[0048] The structural formula of the prepared oxime sulfonate modifier is:

[0049] .

[0050] Table 3: Specific process parameters and material dosages in the preparation process of oxime sulfonate modifiers

[0051]

[0052] According to Example 7 to Example 9, modifier samples 1 to 3 are prepared respectively for later use.

[0053] Embodiment 10 to Embodiment 18

[0054] In this embodiment, desulfurized rubber modified asphalt is prepared, and the specific steps are as follows:

[0055] Weigh 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 mass;

[0056] The petroleum asphalt is heated to a molten state, and modified artificial zeolite and desulfurized rubber powder are added and stirred and mixed. The temperature is raised to 120°C to 135°C, and stirring is continued to make it fully swollen. An oxime sulfonate modifier is added and stirred and mixed to make it develop, so as to prepare desulfurized rubber modified asphalt.

[0057] Table 4: Specific process parameters and material dosage of desulfurized rubber modified asphalt preparation process

[0058]

[0059] In Table 4, the purchased oxime sulfonate compound 1 is 2,3-butanedione bis[O-(butylsulfonyl)oxime, and the structural formula is:

[0060] ;

[0061] The purchased oxime sulfonate compound 2 is 4-[O-[(4-methoxyphenyl)sulfonyl]oxime]-2,6-dimethyl-2,5-cyclohexadiene-1,4-dione, and its structural formula is:

[0062] ;

[0063] The purchased oxime sulfonate compound 3 is 4,5-diazafluorene-9-one O-toluenesulfonyl oxime, and the structural formula is:

[0064] .

[0065] According to Example 10 to Example 18, asphalt samples 1 to asphalt samples 9 were prepared respectively.

[0066] Comparative Example 1

[0067] 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 the present invention is not used, but the rubber powder treated with strong acid desulfurization is used. The specific process is as follows:

[0068] S1. Preparation of desulfurizer

[0069] Mix 10 parts of toluene and 2 parts of acetic acid, add 2 parts of ferric chloride and 2 parts of hydrochloric acid (mass concentration 30%) prepared ferric chloride solution to obtain a desulfurizer, mix well and set aside.

[0070] S2, rubber powder desulfurization process:

[0071] 10 parts of rubber powder were mixed with 100 parts of the desulfurizing agent prepared above, stirred thoroughly, and desulfurized for 8 hours at 50°C;

[0072] S3, Drying:

[0073] The desulfurized rubber powder was filtered, washed with water, and dried to obtain the desulfurized rubber powder reference substance 1 for later use.

[0074] The desulfurized rubber powder reference product 1 was used according to the material ratio of Example 10, the temperature was controlled according to the actual process conditions, and the asphalt state was observed to prepare the asphalt reference product 1.

[0075] Comparative Example 2

[0076] 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 the present invention is not used, but the preparation process of the desulfurized rubber powder is studied. The specific process is as follows:

[0077] S1. Preparation of calcium nitrate solution

[0078] Add 35 parts of calcium nitrate to 200 parts of water, and stir evenly until the calcium nitrate is fully dissolved to prepare a calcium nitrate solution;

[0079] S2, rubber powder desulfurization process:

[0080] 90 parts of rubber powder, 25 parts of aniline and the above calcium nitrate solution were stirred and mixed, and the subsequent preparation process was the same as that in Example 1 to prepare a desulfurized rubber powder reference substance 2 for use.

[0081] The desulfurized rubber powder reference product 2 was used according to the material ratio of Example 10, the temperature was controlled according to the actual process conditions, the asphalt state was observed, and the asphalt reference product 2 was prepared.

[0082] Comparative Example 3

[0083] The implementation method of this comparative example is the same as that of Example 10, except that instead of using the modifier sample 1 prepared by the present invention, 5 parts of hydrogen peroxide are used to prepare the asphalt reference product 3.

[0084] Comparative Example 4

[0085] The implementation method of this comparative example is the same as that of Example 10, except that instead of using the modifier sample 1 prepared by the present invention, 5 parts of a silane coupling agent (vinyl tris(2-methoxyethoxy)silane is used in this comparative example) to prepare an asphalt reference product 4.

[0086] Comparative Example 5

[0087] The implementation method of this comparative example is the same as that of Example 10, except that the modified artificial zeolite 1 prepared by the present invention is not used, but ordinary artificial zeolite of equal mass is used, and the mixing temperature is controlled according to the actual situation during mixing, thereby preparing an asphalt reference product 5.

[0088] Analysis and testing

[0089] 1. Research on desulfurized rubber powder

[0090] (1) Elemental analysis

[0091] Elemental analysis was carried out on waste rubber powder (rubber powder before desulfurization), desulfurized rubber powder samples and reference materials. The results are shown in Table 5.

[0092] Table 5: Elemental analysis results of rubber powder

[0093]

[0094] From the results in Table 5, it can be seen that the S content in the rubber powder does not decrease before and after desulfurization. This is because the desulfurization process does not remove S, but breaks the disulfide bond. At the same time, 2,5-benzothiazole dithiol is introduced into the desulfurization process, which can provide rich C and S elements and increase the ratio of C and S elements. However, as for the increase of O element, since 2,5-benzothiazole dithiol does not contain O element, the increased O element comes from the desulfurization process.

[0095] (2) Cross-link density analysis

[0096] The crosslinking density of waste rubber powder, desulfurized rubber powder and control samples was tested by equilibrium swelling method. The results are shown in Table 6.

[0097] (3) Contact angle analysis

[0098] The contact angle of the waste rubber powder, desulfurized rubber powder and control samples was tested using a contact angle tester. The results are shown in Table 6.

[0099] Table 6: Analysis results of crosslinking density and contact angle of rubber powder

[0100]

[0101] As can be seen from the results in Table 6, the crosslinking density and contact angle of the desulfurized rubber powder of this embodiment are greatly 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 the present invention to desulfurize the rubber powder not only breaks the disulfide bond, but also introduces oxygen-containing groups, thereby increasing the hydrophilicity of the rubber powder surface. At the same time, the 2,5-benzothiazole dithiol introduced in the present invention also provides an active sulfur atom to form a covalent bond with the hydroxyl or carboxyl group on the surface of the rubber powder. Not only does it enhance the surface activity of the rubber powder, but it can also improve the compatibility with the polymer matrix. However, the crosslinking degree and contact angle of the desulfurized rubber powder reference substance 2 are still very high, indicating that the desulfurization process of the comparative example 2 is not sufficient, because calcium nitrate is difficult to dissolve in the organic phase with the rubber powder. The present invention uses 4-methylphenylmagnesium bromide and trimethylchlorosilane through a simple reaction to prepare an onium salt solution with catalytic function, thereby increasing the contact area between calcium nitrate and rubber powder, and thus improving the desulfurization efficiency. This onium salt itself does not participate in the oxidation reaction, so the catalytic efficiency is higher.

[0102] 2. Asphalt performance analysis

[0103] Take asphalt samples and reference materials, and according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTJ 052-2000), the test data can be found in Table 7.

[0104] Table 7: Asphalt sample test data

[0105]

[0106] As can be seen from the results in Table 7, the asphalt samples prepared by the present invention have higher softening point, viscosity and ductility. This may be because the desulfurized rubber powder used in the present invention mainly has disulfide bonds broken, while the main chain is less damaged, and new side chains are introduced into the main chain. In theory, the addition of side chains will increase the network structure, but the side chains introduced by the present invention can provide active sulfur elements, which are easy to diffuse and penetrate small molecule asphalt, providing better high and low temperature performance for asphalt. The increase in ductility represents the enhancement of the plasticity of asphalt. The changes in ductility, tensile strength and elastic recovery before and after aging of the present invention are lower, indicating that the anti-aging ability of the present invention has also been improved. This is because the modifier used in the present invention has special properties, does not require excessively high temperatures during cross-linking, and can react quickly during normal operation. In Examples 16 to 18, three types of purchased oxime sulfonate compounds were selected, and the prepared asphalt performance was close to that of the homemade modifier, and good ductility, tensile strength and elastic recovery performance could be maintained after aging, but the reduction in each performance index after aging was slightly larger.

Claims

1. A desulfurized rubber modified asphalt, characterized in that: In terms of mass, 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; The raw materials for preparing the desulfurized rubber powder include waste rubber powder, calcium nitrate, aniline, 2,5-benzothiazoledithiol, p-methylphenylmagnesium bromide, diphenyl sulfoxide and trimethylsilyl chloride 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: Add 5 to 6 parts of 4-methylphenylmagnesium bromide and 1 part of diphenyl sulfoxide to an inert organic solvent, control the temperature at 12°C to 32°C, dropwise add 3 to 4 parts of trimethylsilyl chloride, react for 2 to 4 hours, quench the reaction with water, adjust the pH value to 1 to 2, retain the aqueous phase after separation and concentrate; Then, 10 to 20 parts of calcium nitrate are added to the concentrated aqueous phase, and stirred evenly until the calcium nitrate is fully dissolved to prepare a calcium nitrate solution; 80 to 100 parts of waste rubber powder, 20 to 30 parts of aniline and the calcium nitrate solution are stirred and mixed, heated to 130°C to 135°C, stirred and reacted for 1h to 2h, and then 5 to 10 parts of 2,5-benzothiazoledithiol are added, and stirred for 0.5h to 1h; Filter, wash with water, and dry to obtain the desulfurized rubber powder; The preparation method of the modified artificial zeolite is as follows: cellulose acetate and artificial zeolite are added to water, heated to 80°C to 110°C, lauric acid is added, stirring is continued and the temperature is raised to 100°C to 115°C, and the modified artificial zeolite is prepared by filtering and drying after heat preservation for 1 h to 2 h; the mass ratio of the cellulose acetate, artificial zeolite and lauric acid is 1:1 to 1.5:0.3 to 0.

8.

2. A desulfurized rubber modified asphalt according to claim 1, characterized in that: The stirring rate of the stirring and mixing is 10 r / min to 15 r / min; the drying temperature of the drying is 45° C. to 60° C.

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. A desulfurized rubber modified asphalt according to claim 3, characterized in that: The acid binding agent is any one of pyridine or triethylamine.

5. A method for preparing desulfurized rubber modified asphalt according to any one of claims 1 to 4, characterized in that: The specific steps of the preparation method are: The petroleum asphalt is heated to a molten state, modified artificial zeolite and desulfurized rubber powder are added, the temperature is raised to 120°C to 135°C, stirring is continued to make it fully swollen, an oxime sulfonate modifier is added, stirring and developing, and the modified asphalt is prepared.

Images