Compound pour point depressant and preparation method thereof

Abstract

The present invention relates to a compound pour point depressant and a preparation method thereof, the compound pour point depressant comprises an ethylene-vinyl acetate copolymer as a main pour point depressant, a polymethacrylate pour point depressant, a synergist, a dispersant and an antioxidant, the ethylene-vinyl acetate copolymer is a maleic acid grafted copolymer, the polymethacrylate pour point depressant is a maleic acid grafted copolymer, and the dispersant is a maleic acid grafted copolymer. The mass ratio of the ethylene-vinyl acetate copolymer to the polymethacrylate pour point depressant is (1-3): 1.

Description

Technical Field

[0001] This invention relates to petroleum additives, and particularly to compound pour point depressants and their manufacturing methods. Background Technology

[0002] With the development of the petroleum industry, the flow properties of petroleum products under low-temperature conditions have become a crucial factor affecting their performance. Especially in cold regions, petroleum products such as diesel, crude oil, and lubricating oil are prone to solidification at low temperatures, leading to decreased flow properties and impacting normal use. To address this issue, pour point depressants, as an important additive, are widely used in petroleum products.

[0003] Pour point depressants primarily work by altering the structure and growth pattern of wax crystals in petroleum products, inhibiting their aggregation and growth, thereby lowering the pour point and improving their low-temperature flow properties. Currently, common pour point depressants on the market include ethylene-vinyl acetate copolymer (EVA), polymethyl methacrylate (PMA), and ethylene-acrylate copolymer.

[0004] In the prior art, Patent Document 1 (CN102559302B) discloses a diesel pour point depressant and its preparation method. This pour point depressant can significantly reduce the cold filter plugging point and pour point of diesel fuel and is widely applicable to various types of diesel fuel with few limitations. Patent Document 2 (CN108997991A) discloses a composite pour point depressant, comprising a polymer pour point depressant and asphalt particles. The polymer pour point depressant includes ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers, etc. This composite pour point depressant simplifies the composition, reduces costs, and improves the pour point depressing effect.

[0005] Patent document 3 (CN107099359B) discloses a method for preparing a diesel pour point depressant and the depressant itself. This method involves adding polyethylene vinyl acetate and polymethacrylate to a reaction vessel, dissolving and reacting them under specific conditions, and then subjecting the mixture to repeated shearing using a shearing device. The preparation is simple, low-cost, and produces a good pour point depressant effect. Patent documents 5 (CN105542063B) and 6 (CN105524211B) disclose two methods for preparing two quaternary copolymer diesel pour point depressants. These quaternary copolymer depressants exhibit significantly better pour point depressant effects than single-component homopolymer depressants.

[0006] However, existing pour point depressants have some shortcomings. First, most pour point depressants are primarily designed for petroleum products such as diesel base oil and crude oil, exhibiting varying degrees of pour point depressing effect on different types of petroleum products. Few studies have focused on the impact of pour point depressants on the low-temperature performance of engine oils, especially their low-temperature pumpability. Second, existing pour point depressants struggle to simultaneously meet the diverse performance requirements of engine oils in low-temperature environments. Furthermore, there is room for optimization in the molecular structure design and component ratios of existing pour point depressants, particularly regarding their limited effectiveness in improving the low-temperature pumpability of engine oils.

[0007] Therefore, there is an urgent need to develop a compound pour point depressant that can effectively improve the low-temperature performance of engine oil, especially its low-temperature pumping performance, to meet the needs of engine oil in cold environments. Summary of the Invention

[0008] The technical problem this invention aims to solve is that most existing pour point depressants have varying degrees of pour point depressing effect on diesel base oils and crude oils, improving their low-temperature fluidity, but do not address their impact on the low-temperature performance of gasoline engine oils, especially their low-temperature pumpability. Therefore, there is a need to provide a pour point depressant that can improve the low-temperature performance of gasoline engine oils, particularly their low-temperature pumpability.

[0009] The technical solution adopted by this invention to solve its technical problem is: to provide a compound pour point depressant, wherein the compound pour point depressant comprises an ethylene-vinyl acetate copolymer, a polymethacrylate pour point depressant, a synergist, a dispersant, and an antioxidant, wherein the ethylene-vinyl acetate copolymer is a maleic acid graft copolymer, and the mass ratio of the ethylene-vinyl acetate copolymer to the polymethacrylate pour point depressant is (1-3):1. The mass ratio can be 1:1, 1.5:1, 2.5:1, 3:1, etc.

[0010] Preferably, the synergist is polyisobutylene succinic anhydride. In this invention, the polar anhydride groups of polyisobutylene succinic anhydride form hydrogen bonds with the ester groups of polymethacrylates, avoiding molecular entanglement, lowering the cloud point, and improving the low-temperature pumping performance of existing pour point depressants. This intermolecular interaction allows the compounded pour point depressant to more effectively inhibit wax crystal growth under low-temperature conditions.

[0011] Furthermore, the dispersant is sorbitan monooleate. In this invention, the sorbitan monooleate (e.g., Span 80) utilizes surface activity to disperse the ethylene-vinyl acetate-maleic anhydride graft copolymer in base oil with a particle size below 5 μm, solving the problems of poor compatibility and high cost, and providing an economical solution for improving the low-temperature performance of high-end gasoline engine oils. In addition, sorbitan monooleate can effectively improve the dispersibility of compounded pour point depressants in crude oil, preventing the pour point depressants from agglomerating and ensuring that the pour point depressants are uniformly dispersed in crude oil, thereby fully exerting their pour point depressing effect.

[0012] The antioxidant is a phenolic antioxidant or an amine antioxidant, preferably 2,6-di-tert-butyl-p-cresol. In this invention, 2,6-di-tert-butyl-p-cresol can effectively prevent oxidative degradation of the compound pour point depressant during use, thus extending the service life of the compound pour point depressant.

[0013] More preferably, the grafting rate of maleic anhydride in the ethylene-vinyl acetate copolymer is 8% to 10%; and the weight-average molecular weight of the ethylene-vinyl acetate copolymer is 60,000 to 80,000. The grafting rate can be 8.2%, 8.5%, 9.0%, 9.5%, 9.8%, etc., and the weight-average molecular weight can be 62,000, 65,000, 70,000, 72,000, 75,000, etc.

[0014] Preferably, the ethylene-vinyl acetate copolymer comprises 20-80 parts by weight, the polymethacrylate pour point depressant comprises 20-80 parts by weight, the synergist comprises 10-40 parts by weight, the dispersant comprises 10-40 parts by weight, and the antioxidant comprises 1-20 parts by weight. The ethylene-vinyl acetate copolymer can be, for example, 30 parts by weight, 40 parts by weight, 60 parts by weight, or 70 parts by weight; the polymethacrylate pour point depressant can be, for example, 30 parts by weight, 40 parts by weight, 60 parts by weight, or 70 parts by weight; the synergist can be, for example, 15 parts by weight, 25 parts by weight, or 35 parts by weight; the dispersant can be, for example, 15 parts by weight, 25 parts by weight, or 35 parts by weight; and the antioxidant can be, for example, 2 parts by weight, 10 parts by weight, or 15 parts by weight.

[0015] This invention also provides a method for manufacturing a compound pour point depressant, comprising:

[0016] 1. Mixing step: Add 30-70 parts by weight of ethylene-vinyl acetate maleic anhydride graft copolymer, 15-40 parts by weight of synergist, 10-30 parts by weight of dispersant, and 1-10 parts by weight of antioxidant to a high-speed dispersion kettle, and stir at 70°C and 1,500 rpm for 60 minutes.

[0017] 2. Homogenization step: The colloid mill is used to circulate and grind twice to make the particle size less than or equal to 5 μm, resulting in a pale yellow transparent liquid;

[0018] 3. Pour point depressant compounding: Mix the above-mentioned light yellow transparent liquid with polymethyl methacrylate pour point depressant at a mass ratio of (1-3):1.

[0019] The beneficial effects of this invention are as follows:

[0020] The compound pour point depressant of this invention is suitable for paraffinic, intermediate, and PAO / mineral oil blended base oils, and can be widely used in multi-grade oils (0W-20, 5W-30) blended from high-wax base oils to improve low-temperature start-up performance. Compared with existing technologies, this invention significantly improves the low-temperature performance of engine oils through the compounding of specific components.

[0021] Experimental data show that the compound pour point depressant of the present invention has a lower pour point (PP) and better low-temperature pumpability (MRV) in 0W-20 and 5W-30 oil products compared with the comparative pour point depressant, proving the technical effect of the compound pour point depressant of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, those skilled in the art can make appropriate adjustments and implementations, and these also fall within the scope of protection of this invention.

[0023] Preparation Example 1

[0024] Add 200g of ethylene-vinyl acetate copolymer (vinyl acetate content 35% by mass, molecular weight 50,000) to a reactor, add 800g of toluene, and stir at 80°C for 1 hour until completely dissolved to form a solution with a concentration of 25% by mass.

[0025] The temperature was raised to 110℃, and nitrogen gas was introduced for protection. After 1 hour, 2.0 g of maleic anhydride and 50 g of a 10% (w / w) dicumyl peroxide toluene solution were added dropwise. The reaction was maintained at this temperature for 4 hours to obtain 1051.93 g of a mixture of ethylene-vinyl acetate maleic anhydride graft copolymer and toluene. The grafting rate was determined by infrared spectroscopy to be 8.87%.

[0026] Toluene was removed by vacuum distillation at -0.09 MPa and 120 °C, yielding 195.75 g of ethylene-vinyl acetate maleic anhydride graft copolymer (98% solid content, 95% recovery rate, and 66,000 weight average molecular weight) as a brownish-yellow viscous liquid.

[0027] Preparation Example 2

[0028] Add 200g of ethylene-vinyl acetate copolymer (vinyl acetate content 35% by mass, molecular weight 50,000) to a reactor, add 800g of toluene, and stir at 80°C for 1 hour until completely dissolved to form a solution with a concentration of 25% by mass.

[0029] The temperature was raised to 110℃, and nitrogen gas was introduced for protection. After 1 hour, 1.8 g of maleic anhydride and 50 g of a 10% (w / w) dicumyl peroxide toluene solution were added dropwise. The reaction was maintained at this temperature for 4 hours to obtain 1051.82 g of a mixture of ethylene-vinyl acetate maleic anhydride graft copolymer and toluene. The grafting rate was determined by infrared spectroscopy to be 9.63%.

[0030] Toluene was removed by vacuum distillation at -0.09 MPa and 120 °C, yielding a brownish-yellow viscous liquid. 195.41 g of ethylene-vinyl acetate-maleic anhydride graft copolymer was obtained, with a solid content of 98%, a recovery rate of 95%, and a weight-average molecular weight of 71,000.

[0031] Example 1:

[0032] 135g of the ethylene-vinyl acetate maleic anhydride graft copolymer obtained in Preparation Example 1, 75g of polyisobutylene succinic anhydride, 60g of Span 80, and 30g of 2,6-di-tert-butyl-p-cresol were added to a high-speed dispersion vessel and stirred at 1,500 rpm for 60 minutes at 70°C.

[0033] Furthermore, the particles were circulated and milled twice using a colloid mill with a gap of 0.1 mm to reduce the particle size to less than 5 μm, yielding 300 g of a pale yellow transparent liquid with a kinematic viscosity of 236 mmHg at 40°C. 2 / s.

[0034] The above-mentioned yellow transparent liquid was mixed with polymethyl methacrylate pour point depressant at a ratio of 3:1 (ethylene-vinyl acetate maleic anhydride graft copolymer: polymethyl methacrylate pour point depressant) to obtain compound pour point depressant 1.

[0035] Example 2:

[0036] 165g of the ethylene-vinyl acetate maleic anhydride graft copolymer obtained in Preparation Example 1, 75g of polyisobutylene succinic anhydride, 45g of Span 80, and 15g of 2,6-di-tert-butyl-p-cresol were added to a high-speed dispersion vessel and stirred at 1,500 rpm for 60 minutes at 70°C.

[0037] Furthermore, the particles were circulated and ground twice using a colloid mill with a gap of 0.1 mm to reduce the particle size to less than 5 μm, yielding 300 g of a pale yellow transparent liquid with a kinematic viscosity of 258 mmHg at 40°C. 2 / s.

[0038] The above-mentioned yellow transparent liquid was mixed with polymethyl methacrylate pour point depressant at a ratio of 2:1 (ethylene-vinyl acetate maleic anhydride graft copolymer: polymethyl methacrylate pour point depressant) to obtain compound pour point depressant 2.

[0039] Example 3:

[0040] 180g of the ethylene-vinyl acetate maleic anhydride graft copolymer obtained in Preparation Example 1, 90g of polyisobutylene succinic anhydride, 15g of Span 80, and 15g of 2,6-di-tert-butyl-p-cresol were added to a high-speed dispersion vessel and stirred at 70°C and 1,500 rpm for 60 minutes.

[0041] Furthermore, the particles were circulated and ground twice using a colloid mill with a gap of 0.1 mm to reduce the particle size to less than 5 μm, yielding 300 g of a pale yellow transparent liquid with a kinematic viscosity of 273 mmHg at 40°C. 2 / s.

[0042] The above-mentioned yellow transparent liquid was mixed with polymethyl methacrylate pour point depressant at a ratio of 1:1 (ethylene-vinyl acetate maleic anhydride graft copolymer: polymethyl methacrylate pour point depressant) to obtain compound pour point depressant 3.

[0043] Comparative Example 1 (EVA pour point depressant):

[0044] Add 2 L of toluene to a 5 L reactor and stir at 300-500 rpm. Purge with nitrogen three times to remove air, and preheat to 60 °C. Add 300 g of vinyl acetate monomer and stir until homogeneous. Turn off the nitrogen gas, introduce ethylene gas, slowly increase the pressure to 10-15 MPa, and heat to 95 °C.

[0045] A 200 mL solution of 5% (w / w) di-tert-butyl peroxide in toluene was added dropwise over 30 minutes using a constant-pressure dropping funnel. The reaction was then maintained at this temperature for 6 hours. During the reaction, ethylene was added to maintain a stable pressure. Solid content was analyzed every 30 minutes, and the reaction was stopped when the solid content reached 35%. After solvent removal and purification, 297.53 g of EVA pour point depressant was obtained.

[0046] Comparative Example 2 (Polymethyl methacrylate pour point depressant):

[0047] In a 1000mL four-necked glass bottle, 120g of tetradecyl methacrylate, 75g of hexadecyl methacrylate, 15g of glycidyl methacrylate, 93.9g of base oil, and 1.50g of n-butanethiol were added respectively. After mixing and stirring evenly, the mixture was heated to 110℃, and 0.6g of azobisisobutyronitrile (AIBN) initiator was added. After maintaining the temperature for 4 hours, the copolymerization reaction was stopped, and 304.8g of polymethacrylate pour point depressant was obtained.

[0048] Test case

[0049] Pour point depressants (PPD) from Examples 1-3 and Comparative Examples 1 and 2 were added to base oils composed of paraffinic base oil, intermediate base oil, and PAO / mineral oil to formulate 0W-20 and 5W-30 engine oils, respectively. In both examples and comparative examples, the amount of pour point depressant was 0.5 by mass relative to the total mass of the pour point depressant and base oil.

[0050] The pour point (PP) of various engine oils was determined using the ASTM D7346 method, and the results are shown in the table below.

[0051] The low-temperature pumpability (MRV) of various engine oils was determined using the ASTM D4684 method, and the results are shown in the table below.

[0052] Table 1. Performance comparison of pour point depressants in 0W-20 oil products between the examples and comparative examples.

[0053]

[0054] Table 2. Performance comparison of pour point depressants in 5W-30 oil products between the examples and comparative examples.

[0055]

[0056] As shown in Tables 1 and 2 above, compared with the pour point depressant in the comparative example, the compound pour point depressant of the present invention can significantly reduce the low-temperature performance of engine oil and improve its low-temperature pumpability. Furthermore, compared with the pour point depressant in the comparative example, the compound pour point depressant of the present invention can significantly reduce the pour point of engine oil, maintain its dissolved state, and avoid dry friction wear.

[0057] Industrial availability

[0058] The compound pour point depressant of this invention, through maleic anhydride graft modification and compound synergy, is suitable for paraffin-based, intermediate-based base oils and PAO / mineral oil mixed base oils. It can be widely used in multi-grade oils (0W-20, 5W-30) blended from high-wax base oils to improve low-temperature pumping performance.

Claims

1. A compound pour point depressant, wherein, The compound pour point depressant comprises ethylene-vinyl acetate copolymer as the main pour point depressant, polymethyl methacrylate pour point depressant, synergist, dispersant and antioxidant, wherein the ethylene-vinyl acetate copolymer is a maleic acid graft copolymer, and the mass ratio of the ethylene-vinyl acetate copolymer to the polymethyl methacrylate pour point depressant is (1-3):

1.

2. The compound pour point depressant as described in claim 1, wherein, The synergist is polyisobutylene succinic anhydride.

3. The compound pour point depressant as described in claim 1 or 2, wherein, The ethylene-vinyl acetate copolymer is 20-80 parts by weight, the polymethacrylate pour point depressant is 20-80 parts by weight, the synergist is 10-40 parts by weight, the dispersant is 10-40 parts by weight, and the antioxidant is 1-20 parts by weight.

4. The compound pour point depressant as described in claim 1 or 2, wherein, The dispersant is sorbitan monooleate, and the antioxidant is 2,6-di-tert-butyl-p-cresol.

5. The compound pour point depressant as described in claim 1 or 2, wherein, The grafting rate of maleic anhydride in the ethylene-vinyl acetate copolymer is 8% to 10%.

6. The compound pour point depressant as described in claim 1 or 2, wherein, The weight-average molecular weight of the ethylene-vinyl acetate copolymer is 60,000 to 80,000.

7. A method for manufacturing a compound pour point depressant, wherein, The manufacturing method includes the following steps: Mixing step: Add 30-70 parts by weight of ethylene-vinyl acetate maleic anhydride graft copolymer, 15-40 parts by weight of synergist, 10-30 parts by weight of dispersant, and 1-10 parts by weight of antioxidant to a high-speed dispersion kettle, and stir at 70°C and 1,500 rpm for 60 minutes. Homogenization step: The colloid mill was used to circulate and grind the particles twice to obtain a particle size of less than or equal to 5 μm, resulting in a pale yellow transparent liquid with a density of 0.92–0.95 g / cm³. 3 Kinematic viscosity at 40℃: 200~300 mm 2 / s; Pour point depressant compounding: Mix the above-mentioned light yellow transparent liquid with polymethyl methacrylate pour point depressant at a mass ratio of (1-3):

1.

8. The method for manufacturing the compound pour point depressant as described in claim 7, wherein, The synergist is polyisobutylene succinic anhydride.

9. The method for manufacturing the compound pour point depressant as described in claim 7 or 8, wherein, The grafting rate of the ethylene-vinyl acetate maleic anhydride graft copolymer is 8% to 10%, and the weight-average molecular weight is 60,000 to 80,000.

10. The method for manufacturing the compound pour point depressant as described in claim 7 or 8, wherein, The dispersant is sorbitan monooleate, and the antioxidant is 2,6-di-tert-butyl-p-cresol.

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