Pour point depressant, its preparation method and application
By preparing a terpolymer type decoagulant, using strong polar groups of styrene to prevent wax crystal aggregation, the limitations of improving the low-temperature performance of asphalt in the prior art are solved, and the balance between improving low-temperature performance and high-temperature performance is achieved.
Patent Information
- Application Number
- CN202310053888.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-02-03
- Publication Date
- 2025-07-25
- Estimated Expiration
- 2043-02-03
AI Technical Summary
Existing decoagulant is rarely used in the field of road engineering, and polyacrylate decoagulant has limitations in improving the low-temperature performance of asphalt, which cannot effectively prevent wax crystals from aggregating, resulting in low-temperature cracking of asphalt.
A terpolymer type degreasing agent is used, which contains styrene with strong polar groups. By adhering to the surface of wax crystal, it increases repulsion, prevents wax crystal aggregation, improves the low-temperature performance of asphalt and maintains high-temperature performance.
It enhances the repulsion between wax crystals, improves the low-temperature performance of asphalt, reduces low-temperature cracking, improves the affinity between asphalt and aggregates, enhances water peeling resistance and adhesion, and does not affect high-temperature performance.
Smart Images
Figure CN115975091B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a pour point depressant and its preparation method and application, belonging to the technical field of modified asphalt for road engineering. Background Art
[0002] Since China's economic reform and opening up, the economy has increased rapidly, the demand for land transportation has grown, heavy traffic has become increasingly frequent, and the requirements for road performance have become higher and higher. In the western plateau and northern regions of China, low-temperature cracking is an important reason for the early damage of asphalt pavements and one of the most important diseases of asphalt pavements.
[0003] According to research, the content of crystalline wax in asphalt is the main factor leading to low-temperature cracking of asphalt. When the temperature is relatively low, the wax crystallizes and precipitates and disperses among other components. At this time, the wax crystals will not only reduce the close connection between molecules, but also when the size of the wax crystals exceeds the limit of the micelles, they will exist in the asphalt in an uneven suspended state. At this time, the wax is equivalent to an impurity in the asphalt, causing cracks in the asphalt.
[0004] A pour point depressant is an additive that can improve the crystallization process of wax. The growth state of wax crystals in asphalt without adding a pour point depressant is two-dimensional and the growth rate is very fast. When the length reaches 200 μm, a rhombic network structure will appear, reducing the fluidity of the asphalt. After adding a pour point depressant, the growth state of the crystals will become three-dimensional growth, and the growth rate in the X and Y axis directions will be greatly reduced; the crystals extend along the Z axis, and the shape changes to a rhombic pyramid or rhombic prism shape. With the increase of the addition amount, the growth rate in the X and Y axis directions slows down until it stops, and the growth rate in the Z axis will continue to increase. At this time, the specific surface area of the wax crystals decreases, and it is not easy to aggregate into larger crystal blocks, so the low-temperature performance of the asphalt is improved.
[0005] There are many types of pour point depressants, including surfactant-type pour point depressants, copolymer-type pour point depressants, and compound-type pour point depressants. The principle of surfactant-type pour point depressants is adsorption. Through the surface adsorption of pour point depressant molecules, the formation of a three-dimensional network structure of wax crystal adhesion is hindered. Currently, well-developed surface-active pour point depressants include petroleum sulfate and polyoxyethylene alkylamine pour point depressants. Copolymer-type pour point depressants are composed of non-polar groups and polar groups. The non-polar groups (such as long-chain alkyl groups) produce a pour point depression effect through eutectic, adsorption, crystal nucleus and other mechanisms, and the polar groups (such as esters, maleic anhydride, etc.) achieve a pour point depression effect by changing the wax crystal morphology and inhibiting the growth of wax crystals. Common copolymer-type pour point depressants include poly(alkyl)acrylate polymers, vinyl acetate polymers (EVA), and maleate or fumarate polymers. Compound-type pour point depressants compound two or more pour point depressants to broaden the application range of pour point depressants. Summary of the Invention
[0006] In view of the fact that pour point depressants are rarely used in the field of road engineering in the prior art, the object of the present invention is to provide a preparation method of a pour point depressant, and the pour point depressant is a ternary copolymer type pour point depressant. Styrene has a strong polar group, which can adhere to the surface of wax crystals, increase the repulsive force between wax crystals, enhance the pour point depressing effect, and make up for the limitations of polyacrylate pour point depressants.
[0007] Another object of the present invention is to provide the application of the above-mentioned pour point depressant. The pour point depressant prevents the formation of larger crystals by the aggregation of microcrystalline wax in asphalt, increases the close connection between molecules, increases the affinity between asphalt and aggregates, and improves the adhesion and water stripping resistance of asphalt.
[0008] To achieve the above object, the present invention is realized through the following technical solutions:
[0009] A preparation method of a pour point depressant includes the following steps:
[0010] (1) Synthesis of acrylate
[0011] By weight, add 30 - 40 parts of octadecyl alcohol and 3 - 5 parts of hydroquinone to a beaker. First, raise the temperature to about 50 - 60 °C to dissolve the octadecyl alcohol and hydroquinone, then add 5 - 6 parts of acrylic acid and 3 - 5 parts of p-toluenesulfonic acid, and raise the temperature to 120 - 140 °C and react for 6 - 8 hours;
[0012] Pour the product into a separatory funnel, add a solution of 10 - 12 parts of 0.5 mol / L sodium hydroxide, let it stand for liquid separation and then drain the waste liquid, then wash with hot distilled water, wash repeatedly until the pH is neutral, and dry with 60 - 68 parts of anhydrous calcium chloride to obtain octadecyl acrylate;
[0013] (2) Synthesis of polystyrene - vinyl acetate - octadecyl acrylate
[0014] Add 30 - 38 parts of the octadecyl acrylate prepared in step (1) to a flask, add 120 - 130 parts of toluene for dissolution. After the dissolution is completed, add 3 - 5 parts of benzoyl peroxide. At this time, benzoyl peroxide is used as an initiator, then introduce nitrogen for 15 - 20 min, add 60 - 70 parts of vinyl acetate and 75 - 80 parts of styrene, heat in a water bath to 80 - 90 °C, and stir continuously to obtain polystyrene - ethyl acetate - octadecyl acrylate.
[0015] A pour point depressant prepared by the above preparation method.
[0016] An application of the above pour point depressant in asphalt modification, and the method steps of the application are as follows:
[0017] 1) Preparation of SBS modified asphalt: Keep the asphalt in an oven at 160°C - 170°C for 30 - 40 minutes, then take it out, add SBS, and use a shear machine to shear at a rate of 4000 - 5000 r / min at 170 - 180°C for 30 - 45 minutes. After stirring, put it into an oven at 170 - 180°C for swelling and development for 30 minutes;
[0018] 2) Adding pour point depressant: At a temperature of 170 - 180°C, use a shear machine with a shear rate of 1500 - 1800 r / min, shear for 20 - 30 minutes, and after stirring, put it into an oven at 170 - 175°C for swelling and development for 20 minutes to obtain high-performance modified asphalt doped with a pour point depressant.
[0019] Preferably, the mass ratio of the asphalt to the SBS is 600:(18 - 27).
[0020] The advantages of the present invention are as follows:
[0021] 1. The solubility of n-alkanes in asphalt is low. As the temperature continues to decrease, n-alkanes will first precipitate or solidify in the state of wax crystal aggregation, then form needle-shaped crystals, and adjacent molecules crosslink with each other, and finally form a network structure. In the terpolymer type pour point depressant in the pour point depressant prepared by the present invention, styrene has a strong polar group, which can adhere to the surface of wax crystals, increase the repulsive force between wax crystals, enhance the pour point depressing effect, and make up for the limitations of polyacrylate pour point depressants.
[0022] 2. The pour point depressant prepared by the present invention can not only improve the low-temperature performance of asphalt, but also has no precipitation of wax crystals under high-temperature conditions and does not affect the high-temperature performance of asphalt.
[0023] 3. The pour point depressant prepared by the present invention prevents the formation of larger crystals by the aggregation of microcrystalline wax in asphalt, increases the close connection between molecules, increases the affinity between asphalt and aggregates, and improves the adhesion and water stripping resistance of asphalt.
[0024] 4. The pour point depressant prepared by the present invention can improve the low-temperature performance of asphalt, reduce the low-temperature cracking of asphalt pavement, and has a great improvement on the pavement performance in alpine regions. Description of the Drawings
[0025] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, and do not constitute a limitation to the present invention.
[0026] Figure 1 Infrared spectrum diagram of polystyrene - vinyl acetate - octadecyl acrylate prepared for Example 1. Detailed Embodiments
[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0028] Example 1
[0029] A method for preparing the pour point depressant includes the following steps:
[0030] 1) Synthesis of acrylate
[0031] According to the above weight parts, add 30 parts of octadecyl alcohol and 5 parts of hydroquinone into a beaker. First, raise the temperature to about 50°C to dissolve the octadecyl alcohol and hydroquinone, then add 5 parts of acrylic acid and 5 parts of p-toluenesulfonic acid, and raise the temperature to 120°C for reaction for 8 hours;
[0032] Pour the product into a separatory funnel, add 10 parts of a 0.5 mol / L sodium hydroxide solution at a temperature of 45°C, let it stand for liquid separation and then drain the waste liquid, and then wash it with distilled water at 38°C and wash repeatedly until the pH is neutral, and add 68 parts of anhydrous calcium chloride for drying to obtain acrylate;
[0033] 2) Synthesis of polystyrene-vinyl acetate-octadecyl acrylate
[0034] Add 30 parts of octadecyl acrylate into a flask, add 130 parts of toluene for dissolution. After the dissolution is completed, add 3 parts of benzoyl peroxide. At this time, benzoyl peroxide is used as an initiator, then introduce nitrogen for 20 min, add 60 parts of vinyl acetate and 80 parts of styrene, heat in a water bath to 80°C, and stir continuously to obtain polystyrene-ethyl acetate-octadecyl acrylate.
[0035] Use infrared spectroscopy to analyze polystyrene-vinyl acetate-octadecyl acrylate, and the infrared spectrum is as Figure 1 shown. An ester group C=O vibration absorption peak appears at 1728 cm -1 The C=C bond absorption peak at 1650 cm -1 disappears, and the 1188 cm -1 is the ester group C-O stretching vibration peak; the 1455 cm -1 is the benzene ring skeleton vibration absorption peak, and the vibration peak of the alcohol hydroxyl group at 3500 cm -1 disappears, indicating that the copolymerization of octadecyl acrylate, vinyl acetate and styrene is complete.
[0036] Example 2
[0037] A method for preparing a pour point depressant includes the following steps:
[0038] (1) Synthesis of acrylate
[0039] According to parts by weight, add 40 parts of stearyl alcohol and 3 parts of hydroquinone into a beaker. First, raise the temperature to 60 °C to dissolve the stearyl alcohol and hydroquinone, then add 6 parts of acrylic acid and 3 parts of p-toluenesulfonic acid, and raise the temperature to 140 °C for reaction for 6 hours;
[0040] Pour the product into a separatory funnel, add a solution of 12 parts of 0.5 mol / L sodium hydroxide, let it stand for liquid separation and then drain the waste liquid, and then wash it with hot distilled water, wash repeatedly until the pH is neutral, add 60 parts of anhydrous calcium chloride for drying to obtain octadecyl acrylate;
[0041] (2) Synthesis of polystyrene-vinyl acetate-octadecyl acrylate
[0042] Add 38 parts of the octadecyl acrylate prepared in step (1) into a flask, add 120 parts of toluene for dissolution. After the dissolution is completed, add 5 parts of benzoyl peroxide. At this time, benzoyl peroxide is used as an initiator, then introduce nitrogen for 15 min, add 70 parts of vinyl acetate and 750 parts of styrene, heat in a water bath to 90 °C, and stir continuously to obtain polystyrene-ethyl acetate-octadecyl acrylate.
[0043] Example 3
[0044] Application of a pour point depressant prepared in Example 1 in asphalt modification, the method steps of the application are as follows:
[0045] 1) Preparation of SBS modified asphalt: Keep the asphalt in an oven at 160 °C for 40 min and take it out, add SBS, use a shear machine to shear at 170 °C and a rate of 5000 r / min for 30 min, and then put it into an oven at 180 °C for swelling and development for 30 min; Among them
[0046] 2) Add pour point depressant: At a temperature of 170 °C, use a shear machine with a shear rate of 1800 r / min to shear for 20 min, and then put it into an oven at 175 °C for swelling and development for 20 min to obtain high-performance modified asphalt doped with a pour point depressant.
[0047] The dosage ratio of the above raw materials is formulated according to Table 1, and the matrix asphalt uses Esso 70 # Asphalt (Esso70 # )
[0048] Table 1 Raw material ratio
[0049] Serial number Base asphalt SBS Pour point depressant A 600g 0 0 B 600g 18g 0 C 600g 18g 6g D 600g 27g 0g E 600g 27g 6g F 600g 27g 12g
[0050] Example 3
[0051] Example of Penetration Test of Pour Point Depressant Compound Modified Asphalt at 25°C
[0052] The high-performance modified asphalt prepared in Example 2 was subjected to a penetration test at 25°C and a ductility test at 5°C respectively in accordance with T 0604-2011 and T 0606-2011 of "Test Regulations for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The test results are shown in Table 2:
[0053] Table 2 Low-temperature Experimental Data
[0054] Serial number Penetration at 25°C / (0.1 mm) Ductility at 5°C / cm A 64 11.2 B 62 24 C 59 29 D 55 33 E 52 37 F 50 40
[0055] Example 4
[0056] Example of Bending Beam Rheometer (BBR) Test of Pour Point Depressant Compound Modified Asphalt
[0057] The high-performance modified asphalt prepared in Example 3 was tested at -18°C using a bending beam rheometer (BBR) in accordance with T 0627-2011 of "Test Regulations for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011) to study its low-temperature rheological properties. The stiffness modulus index S is shown in Table 3, and the creep rate is shown in Table 4.
[0058] Table 3 Technical Index of Stiffness Modulus S in Bending Beam Test (BBR)
[0059] Stiffness modulus S (MPa) -18℃ A 391 B 246 C 238 D 281 E 269 F 241
[0060] Table 4 Technical Index of Creep Rate m in Bending Beam Test (BBR)
[0061]
[0062]
[0063] As can be seen from Table 3 and Table 4, at low temperatures, due to the addition of the pour point depressant, the stiffness of the asphalt increases slowly at low temperatures, it can maintain good stress relaxation ability, is not easy to crack, and has good low-temperature performance.
[0064] Example 5
[0065] Example of Bond Beam Strength (BBS) Test of Pour Point Depressant Compound Modified Asphalt
[0066] The high-performance modified asphalt prepared in Example 3 was used to study the adhesion performance of the pour point depressant compound modified asphalt by the BBS test in accordance with ASSHTO TP-91; the molding of the specimens and the steps are as follows:
[0067] (1) Heat the basalt slab and the pull head at 170 °C for 1 h for later use. At the same time, heat the pour point depressant compound modified asphalt prepared in Example 3 to a liquid state at 170 °C.
[0068] (2) Drop about 1 g of the pour point depressant compound modified asphalt onto the basalt slab, then immediately place the [object not specified] on the asphalt and apply a constant load to allow the excess asphalt to flow out of the overflow hole, ensuring that the thickness of the asphalt film is 0.2 mm.
[0069] (3) Let the specimen stand at 25 °C for 1 h, then place it in water at 40 °C for water bath curing. The water bath curing times are 24 h and 48 h respectively. After the water bath curing is completed, place it in a constant temperature and humidity chamber (25 °C, relative humidity 30%) and let it stand for 1 h. Immediately conduct the BBS test after taking it out, and the bond strength of the asphalt is shown in Table 5:
[0070] Table 5 Pull-out test (BBS) data
[0071] Viscosity strength (MPa) 24h 48h A 0.73 0.49 B 1.32 0.86 C 1.18 0.75 D 1.76 1.41 E 1.62 1.26 F 1.49 1.05
[0072] As can be seen from Table 5, for the modified asphalt added with the pour point depressant prepared in Example 3, in the pull-out test, its adhesion strength is greater than that of the original asphalt without the pour point depressant. This shows that the pour point depressant compound modified asphalt can enhance the adhesion between the asphalt and the aggregate within a reasonable mixing ratio range, and the ability of its asphalt mixture to resist water damage is also stronger.
[0073] Example 6
[0074] Example of freeze-thaw splitting test of pour point depressant compound modified asphalt
[0075] Refer to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20 - 2011) T 0729 - 2011 to test the freeze-thaw splitting strength of the asphalt mixture with the high-performance modified asphalt prepared in Example 3. Vacuum saturate the prepared SMA-13 Marshall specimens at a vacuum degree of 97.3 - 98.7 kPa to allow water to fully penetrate into the voids of the asphalt mixture. Subsequently, place them in a low-temperature environment chamber at -18 °C for 16 h, then place them in a water bath at 60 °C for 24 h for freeze-thaw cycling. Finally, place them in a constant temperature water bath at 25 °C and soak for 2 h, and then measure the splitting strength. The test results are shown in Table 6:
[0076] Table 6 Freeze-thaw splitting test results
[0077]
[0078] As can be seen from Table 6, for the modified asphalt with pour point depressant prepared in Example 2, after freeze-thaw cycles, its freeze-thaw splitting strength ratio is greater than that of the original asphalt without pour point depressant, indicating that the modified asphalt with the compounded pour point depressant can make the asphalt exhibit good freeze-thaw damage resistance performance within a reasonable proportion range.
[0079] Example 7
[0080] Example of rutting factor test for modified asphalt with compounded pour point depressant
[0081] Regarding the high-performance modified asphalt prepared in Example 3, referring to the rutting factor G*
[0082] / sinδ proposed in the SHRP specification as an index to evaluate the high-temperature stability of asphalt binder, the high-temperature stability test of asphalt was carried out, and the results are shown in Table 7:
[0083] Table 7 Technical indexes of rutting factor G* / sinδ
[0084]
[0085]
[0086] As can be seen from Table 7, for the modified asphalt with pour point depressant prepared in Example 3, when the modulus decreases at high temperature, the rutting factor decreases slowly, and the rutting resistance ability is the same as that of the original asphalt without pour point depressant, indicating that the modified asphalt with the compounded pour point depressant can maintain the ability of the original asphalt to resist flow deformation within a reasonable proportion range, and the addition of the pour point depressant does not affect the high-temperature performance of the asphalt.
[0087] Example 8
[0088] Example of LAS fatigue test for modified asphalt with compounded pour point depressant
[0089] The high-performance modified asphalt prepared in Example 3 was subjected to a linear amplitude sweep test (Linear Amplitude Sweep, LAS), and the S-VECD analysis method was used to analyze the test data. The maximum strain level was selected as the failure index to determine the LAS test fatigue life of each modified asphalt. The fatigue life results at 5%, 10%,
[0090] The fatigue life results at 15% stress level are shown in Table 8: Table 8 Technical indexes of fatigue life
[0091] Serial number 5％ 10％ 15％ A 1061 276 126 B 7116 1209 389 C 8207 1476 541 D 9649 1697 614 E 9867 1832 936 F 11450 2140 1197
[0092] As can be seen from Table 8, the modified asphalt with pour point depressant prepared in Example 3 has a higher fatigue life than the asphalt without pour point depressant at stress levels of 5%, 10%, and 15%, and the fatigue life is proportional to the dosage of pour point depressant, indicating that the modified asphalt with compounded pour point depressant can increase the fatigue life of the original asphalt and reduce the stress sensitivity of the original asphalt.
[0093] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. Application of a pour point depressant, characterized in that, The pour point depressant is polystyrene-vinyl acetate-octadecyl acrylate, and the preparation method is as follows: (1)Synthesis of acrylate Mix octadecanol and hydroquinone, dissolve them at 50-60°C, then add acrylic acid and p-toluenesulfonic acid, heat up to 120-140°C, react for 6-8 hours, add sodium hydroxide solution, let it stand for liquid separation, wash, and dry to obtain octadecyl acrylate; the mass ratio of octadecanol, hydroquinone, acrylic acid, toluenesulfonic acid and sodium hydroxide solution is: (30-40):(3-5):(5-6):(3-5):(10-12); (2)Synthesis of polystyrene-vinyl acetate-octadecyl acrylate Add toluene to the octadecyl acrylate prepared in step (1) and dissolve it, add benzoyl peroxide, introduce nitrogen, add vinyl acetate and styrene, heat in a water bath to 80°C, stir to obtain polystyrene-ethyl acetate-octadecyl acrylate, that is, the pour point depressant; The pour point depressant is used for asphalt modification, and the application method is as follows: 1) Preparation of SBS modified asphalt: Keep the asphalt at 160°C - 170°C for 30 - 40 min and take it out, add SBS, use a shearing machine to shear at a rate of 170 - 180°C and 4000 - 5000 r / min for 30 - 45 min, after stirring, put it into an oven at 170 - 180°C for swelling and development for 30 min; the mass ratio of the asphalt and SBS is 600:18 - 27; 2) Add the pour point depressant: Add the pour point depressant to the modified asphalt treated in step 1), shear at a temperature of 170 - 180°C, the shear rate is 1500 - 1800 r / min, shear for 20 - 30 min, after shearing, put it into an oven at 170 - 175°C for swelling and development for 20 min to obtain the high-performance modified asphalt doped with the pour point depressant.
2. The application according to claim 1, characterized in that The concentration of the sodium hydroxide solution in step (1) is 0.5mol / L.
3. The application according to claim 1, characterized in that, The mass ratio of the octadecyl acrylate, toluene, benzoyl peroxide, vinyl acetate and styrene in step (2) is: (30-38):(120-130):(3-5):(60-76):(75-80).
4. The application according to claim 1, characterized in that The specific operation of adding the sodium hydroxide solution and standing for liquid separation in step (1) is: Pour the reaction product into a separatory funnel, add the sodium hydroxide solution, stand for liquid separation and drain the waste liquid, then wash with distilled water, wash repeatedly until the pH is neutral, add anhydrous calcium chloride for drying to obtain octadecyl acrylate.
5. The application according to claim 1, wherein, The time for introducing nitrogen in step (2) is 15 - 20 min.