Viscosity index improver and preparation method thereof

Abstract

The invention provides a viscosity index improver and a preparation method thereof. The viscosity index improver is a copolymer of methacrylic acid C8-C12 alkyl ester, methacrylic acid C13-C18 alkyl ester and N-vinyl imidazole, and the viscosity index improver comprises the following components in percentage by weight: 40%-70% of methacrylic acid C8-C12 alkyl ester, 10%-50% of methacrylic acid C13-C18 alkyl ester and 5%-40% of N-vinyl imidazole in terms of polymeric monomers. The viscosity index improver disclosed by the invention has excellent viscosity-temperature performance and tackifying capacity, also has a good pour point depressing effect, has relatively good wear resistance and dispersing performance, and is a multifunctional viscosity index improver.

Description

Technical Field

[0001] This invention relates to a viscosity index improver and its preparation method, and particularly to a viscosity index improver suitable for use in lubricating oils and its preparation method. Background Technology

[0002] Lubricating oils have lower viscosity at high temperatures, making them more prone to friction and wear, and higher viscosity at low temperatures, leading to viscous friction or even solidification and reduced lubrication efficiency. To meet the requirements of high-temperature lubricity and low-temperature fluidity, viscosity index improvers are added to enhance the viscosity-temperature properties of lubricating oils. This results in better low-temperature starting performance and high-temperature lubrication capabilities, reducing fuel and oil consumption, minimizing engine wear, and extending the service life of the lubricating oil.

[0003] Viscosity index improvers are oil-soluble polymers. Currently, the main viscosity index improvers on the market include ethylene-propylene copolymer (OCP), star-shaped hydrogenated styrene-isoprene copolymer (HSD), polyisobutylene (PIB), and polymethyl methacrylate (PMA). Compared to the other three viscosity index improvers, PMA viscosity index improver, as an excellent lubricant additive, can improve the viscosity-temperature properties and low-temperature performance of oils.

[0004] CN 102295972A discloses a methacrylate-type viscosity index improver and its preparation method. The method involves copolymerizing alkyl methacrylate and alkyl thiol methacrylate to obtain a viscosity index improver with anti-wear properties.

[0005] CN 114369196A discloses a polymethacrylate type viscosity index improver, which is a viscosity index improver with excellent low-temperature performance and thickening properties obtained by copolymerization of different types of alkyl methacrylate monomers.

[0006] With the development of automotive technology and the increasing demands for energy conservation, environmental protection, and economy from various countries, the development of multifunctional PMA viscosity index improvers is an inevitable trend in the development of additives. Developing PMA viscosity index improvers that simultaneously possess thickening, pour point depressing, dispersing, and anti-wear properties remains a focus of effort for those skilled in the art. Summary of the Invention

[0007] This invention proposes a viscosity index improver and its preparation method.

[0008] The viscosity index improver of this invention is C8-C4 methacrylic acid. 12 Alkyl esters, C methacrylic acid 13 ~C 18A copolymer of alkyl esters and N-vinylimidazole, in the viscosity index improver, comprising, by weight, 40% to 70% of C8-C4 methacrylic acid based on the monomer content. 12 Alkyl esters, 10%–50% (by weight) of C methacrylate 13 ~C 18 Alkyl esters, 5% to 40% (by weight) of N-vinylimidazole.

[0009] According to the present invention, the viscosity index improver contains 50% to 70% (by weight) of C8-C6 methacrylic acid, based on the number of polymerizable monomers. 12 Alkyl esters, 20%–40% (by weight) of C methacrylate 13 ~C 18 Alkyl esters, 5% to 30% (by weight) of N-vinylimidazole.

[0010] According to the present invention, the viscosity index improver has a number-average molecular weight of 2,000 to 100,000 g / mol, preferably 10,000 to 50,000 g / mol. The number-average molecular weight is determined by gel permeation chromatography (GPC) using commercially available polymethyl methacrylate standards.

[0011] The method for preparing the viscosity index improver of the present invention includes: reacting methacrylic acid with C8-C64... 12 Alkyl esters, C methacrylic acid 13 ~C 18 Alkyl esters, N-vinylimidazole, chain transfer agents, initiators, and solvents are mixed uniformly and copolymerized under nitrogen protection. The viscosity index improver product is then collected.

[0012] According to the present invention, the temperature of the copolymerization reaction can be 50-150°C, preferably 60-100°C; the time of the copolymerization reaction can be 2-10 hours, preferably 3-8 hours.

[0013] According to the present invention, in preparing the viscosity index improver, the methacrylic acid C8-C6 is calculated based on the polymerizable monomers. 12 Alkyl esters, C methacrylic acid 13 ~C 18 The molar ratio between alkyl ester and N-vinylimidazole can be 6:1 to 8:1 to 10, preferably 3:1 to 3:1 to 4.

[0014] According to the present invention, the chain transfer agent is trithiocarbonate alkyl propionic acid, for example, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid. The amount of the chain transfer agent added is C8-C6 methacrylic acid. 12 Alkyl esters, C methacrylic acid 13 ~C 18The alkyl ester and N-vinylimidazole together account for 0.1% to 3% by weight, preferably 0.3% to 2%.

[0015] According to the present invention, the initiator may be one or more selected from azobisisobutyronitrile, benzoyl peroxide, and tert-butyl peroxide, preferably azobisisobutyronitrile; the amount of the initiator added is C8-C6 methacrylic acid. 12 Alkyl esters, C methacrylic acid 13 ~C 18 The initiator is added at a weight of 0.1% to 3%, preferably 0.2% to 2%, of the sum of the weights of the alkyl ester and N-vinylimidazole. The initiator may be added all at once or in multiple additions, such as two or three times, without particular limitation.

[0016] According to the present invention, the solvent may be one or more selected from toluene, cyclohexane, n-hexane, and petroleum ether; the amount of solvent added is C8-C6 methacrylic acid. 12 Alkyl esters, C methacrylic acid 13 ~C 18 The alkyl ester and N-vinylimidazole together account for 10% to 200% by weight, preferably 20% to 150%.

[0017] According to the present invention, after the copolymerization reaction is completed, the reaction solution can be dropwise added to a C1-C4 alcohol, the precipitate can be collected, and after drying, the viscosity index improver of the present invention can be obtained. The C1-C4 alcohol can be one or more of methanol, ethanol, propanol, and butanol, preferably ethanol. The amount of the C1-C4 alcohol can be the same as that of the C8-C4 methacrylic acid. 12 Alkyl esters, C methacrylic acid 13 ~C 18 The total mass of alkyl esters and N-vinylimidazole is 50% to 1200%.

[0018] The viscosity index improver of the present invention has excellent viscosity-temperature properties and thickening ability, as well as good pour point depressing effect, and also has good anti-wear ability and dispersing performance. It is a multifunctional viscosity index improver. Detailed Implementation

[0019] The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0020] The main raw materials used are sourced from the following sources:

[0021] Methyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.

[0022] Isooctyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0023] Decyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0024] Dodecyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0025] Tetradecyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0026] Cetyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0027] Octadecyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0028] 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0029] Azobisisobutyronitrile (AIBN), analytical grade, Beijing Innocare Technology Co., Ltd.

[0030] Ethanol, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0031] Toluene, analytical grade, Beijing Innocare Technology Co., Ltd.

[0032] III4 base oil, Guangdong Maoming Petrochemical Company.

[0033] The testing method for the viscosity index improver in this invention is shown in Table 1.

[0034] Table 1

[0035]

[0036] Example 1: Preparation of viscosity index improver

[0037] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 17.9 g of dodecyl methacrylate, 6.22 g of tetradecyl methacrylate, 2.17 g of N-vinylimidazole, 346 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 47 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 47 mg of AIBN, and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of dodecyl methacrylate, tetradecyl methacrylate, and N-vinylimidazole, which is the viscosity index improver 1 of this invention.

[0038] Example 2: Preparation of viscosity index improver

[0039] To a three-necked flask equipped with an electric stirrer, add 90 mL of toluene, 97.62 g of dodecyl methacrylate, 33.9 g of tetradecyl methacrylate, 21.2 g of N-vinylimidazole, 1107 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 165 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 165 mg of AIBN, and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 720 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of dodecyl methacrylate, tetradecyl methacrylate, and N-vinylimidazole, which is the viscosity index improver 2 of this invention.

[0040] Example 3: Preparation of viscosity index improver

[0041] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 16.3 g of dodecyl methacrylate, 5.7 g of tetradecyl methacrylate, 5.2 g of N-vinylimidazole, 412 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 50 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 50 mg of AIBN, and continue stirring at 70°C for another 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of dodecyl methacrylate, tetradecyl methacrylate, and N-vinylimidazole, which is the viscosity index improver 3 of this invention.

[0042] Example 4: Preparation of viscosity index improver

[0043] To a three-necked flask equipped with an electric stirrer, add 60 mL of toluene, 42.76 g of isooctyl methacrylate, 24.9 g of hexadecyl methacrylate, 8.5 g of N-vinylimidazole, 550 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 145 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 145 mg of AIBN, and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of isooctyl methacrylate, hexadecyl methacrylate, and N-vinylimidazole, which is the viscosity index improver 4 of this invention.

[0044] Example 5: Preparation of viscosity index improver

[0045] To a three-necked flask equipped with an electric stirrer, add 90 mL of toluene, 61 g of decyl methacrylate, 34 g of octadecyl methacrylate, 9.4 g of N-vinylimidazole, 685 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 150 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 150 mg of AIBN, and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 400 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of decyl methacrylate, octadecyl methacrylate, and N-vinylimidazole, which is the viscosity index improver 5 of this invention.

[0046] Comparative Example 1: Preparation of a Comparative Viscosity Index Improver

[0047] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 37.82 g of dodecyl methacrylate, 13.12 g of tetradecyl methacrylate, 4.88 g of methyl methacrylate, 370 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 110 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 110 mg of AIBN, and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of dodecyl methacrylate, tetradecyl methacrylate, and methyl methacrylate, which is the comparative viscosity index improver 1 of this invention.

[0048] Comparative Example 2: Preparation of a Comparative Viscosity Index Improver

[0049] To a three-necked flask equipped with an electric stirrer, add 82 mL of toluene, 61 g of decyl methacrylate, 34 g of octadecyl methacrylate, 623 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 136 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 136 mg of AIBN and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 364 mL of ethanol, collect the precipitate, and dry it to obtain a copolymer of decyl methacrylate and octadecyl methacrylate, which is the comparative viscosity index improver 2 of this invention.

[0050] Comparative Example 3: Preparation of a Comparative Viscosity Index Improver

[0051] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 41 g of dodecyl methacrylate, 15 g of tetradecyl methacrylate, 370 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 108 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 108 mg of AIBN and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain a copolymer of dodecyl methacrylate and tetradecyl methacrylate, which is the comparative viscosity index improver 3 of this invention.

[0052] Comparative Example 4: Preparation of a viscosity index improver

[0053] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 62 g of dodecyl methacrylate, 370 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 105 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 105 mg of AIBN and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain poly(dodecyl methacrylate), which is the comparative viscosity index improver 4 of this invention.

[0054] Comparative Example 5: Preparation of a viscosity index improver

[0055] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 69 g of tetradecyl methacrylate, 180 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 108 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 108 mg of AIBN and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain polytetradecyl methacrylate, which is the comparative viscosity index improver 5 of this invention.

[0056] According to the test methods in Table 1, the viscosity index, thickening ability, pour point depressing performance, dispersion performance and anti-wear performance of the viscosity index improvers prepared in the examples and comparative examples were determined respectively. The test results are shown in Table 2.

[0057] As shown in Table 2, the viscosity index improver of the present invention has excellent viscosity-temperature properties and thickening ability when the molecular weight is smaller than that of the alkyl methacrylate viscosity index improver in the comparative example. This indicates that the viscosity index improver of the present invention has excellent ability to improve viscosity index and thicken, while also having good pour point depressing effect, and good anti-wear ability and dispersing performance.

[0058] Generally, the larger the molecular weight of a polymer, the stronger its thickening ability. Although the molecular weight of the viscosity index improver of this invention is smaller than that of the comparative viscosity index improver, the thickening ability of the viscosity index improver of this invention is greater than that of the comparative example, indicating that the viscosity index improver of this invention has excellent thickening ability. Simultaneously, the viscosity index of the viscosity index improver of this invention is greater than that of the comparative example, indicating that the viscosity index improver of this invention has excellent thickening ability and viscosity-temperature properties; the viscosity index improvers of comparative examples 4 and 5 have almost no pour point depressing ability, which shows that the viscosity index improver of this invention has a good pour point depressing effect, and the viscosity index improver of this invention also has good anti-wear ability and dispersing properties. Therefore, the viscosity index improver of this invention is a multifunctional viscosity index improver.

[0059] Table 2

[0060]

[0061] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention are within the scope of protection of the present invention.

Claims

1. A viscosity index improver, comprising methacrylic acid C8-C64. 12 Alkyl esters, C methacrylic acid 13 ~C 18 A copolymer of alkyl esters and N-vinylimidazole, in the viscosity index improver, comprising, by weight, 40% to 70% of C8-C4 methacrylic acid based on the monomer content. 12 Alkyl esters, 10%–50% (by weight) of C methacrylate 13 ~C 18 Alkyl esters, 5% to 40% (by weight) of N-vinylimidazole.

2. The viscosity index improver according to claim 1, characterized in that, The viscosity index improver, based on the monomer content, contains 50% to 70% (by weight) of C8-C4 methacrylic acid. 12 Alkyl esters, 20%–40% (by weight) of C methacrylate 13 ~C 18 Alkyl esters, 5% to 30% (by weight) of N-vinylimidazole.

3. The viscosity index improver according to claim 1, characterized in that, The viscosity index improver has a number average molecular weight of 2,000 to 100,000 g / mol.

4. A method for preparing the viscosity index improver according to claim 1, comprising: C8-C999 methacrylic acid 12 Alkyl esters, C methacrylic acid 13 ~C 18 Alkyl esters, N-vinylimidazole, chain transfer agents, initiators, and solvents are mixed uniformly and copolymerized under nitrogen protection. The viscosity index improver product is then collected.

5. The preparation method according to claim 4, characterized in that, The copolymerization reaction is carried out at a temperature of 50–150°C (preferably 60–100°C) and for a duration of 2–10 h (preferably 3–8 h).

6. The preparation method according to claim 4, characterized in that, In preparing the viscosity index improver, based on the polymer monomer, the methacrylic acid C8-C9... 12 Alkyl esters, C methacrylic acid 13 ~C 18 The molar ratio between alkyl ester and N-vinylimidazole is 6:1 to 8:1 to 10 (preferably 3:1 to 3:1 to 4).

7. The preparation method according to claim 4, characterized in that, The chain transfer agent is trithiocarbonate alkyl propionic acid.

8. The preparation method according to claim 4, characterized in that, The initiator is selected from one or more of azobisisobutyronitrile, benzoyl peroxide, and tert-butyl peroxide.

9. The preparation method according to claim 4, characterized in that, The solvent is one or more of toluene, cyclohexane, n-hexane, and petroleum ether.

10. The preparation method according to claim 4, characterized in that, After the copolymerization reaction is complete, the reaction solution is added dropwise to a C1-C4 alcohol, the precipitate is collected, and after drying, the viscosity index improver is obtained.

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