CN-113461881-B - Viscosity index improver concentrate prepared in situ in low-viscosity base oil and preparation method thereof

Abstract

The invention relates to a viscosity index improver concentrated solution applied to lubricating oil, in particular to a viscosity index improver concentrated solution (concentrated solution of star hydrogenated styrene (S) -isoprene (I) -butadiene (B) terpolymer viscosity index improver) prepared in situ in low-viscosity base oil and a preparation method thereof. The star-shaped viscosity index improver is synthesized by polymerizing, hydrogenating and deashing monomers in the concentration of 5-15 wt% of the system in the low-viscosity base oil to directly obtain the viscosity index improver concentrated solution. The method for synthesizing the star-shaped viscosity index improver in situ in the low-viscosity base oil reduces the procedures of solvent removal, solvent recovery, product drying, redissolution and the like in the traditional synthesis method of the viscosity index improver, reduces the production cost and ensures the product quality. The invention also provides a method for preparing the viscosity index improver concentrate in situ in a low viscosity base oil.

Inventors

• LI WEI
• YU SHENGNAN
• CHEN ERZHONG
• YAN XIAOYU
• LIU XIAOJIE
• E YANPENG
• LU JUNDIAN
• LIU GE
• SUN MENGYAO
• ZHANG JIAO

Assignees

• 沈阳化工研究院有限公司

Dates

Publication Date

20260505

Application Date

20210630

Claims (5)

1. 1. A method for preparing a viscosity index improver concentrated solution in situ in low-viscosity base oil is characterized in that the star-shaped viscosity index improver is synthesized by polymerizing, hydrogenating and deashing monomers in the low-viscosity base oil at the concentration of 5-15 wt% of the system to directly obtain the viscosity index improver concentrated solution; the preparation method comprises the following steps: Adding isoprene and butadiene into base oil, adding an alkyl lithium initiator to initiate polymerization at 20-90 ℃, reacting to obtain isoprene and butadiene random copolymer I/B when the conversion rate of the isoprene and the butadiene exceeds 95%, adding styrene to continue the reaction at 20-90 ℃ until the conversion rate of the styrene exceeds 95% to obtain I/B-S two-block polymer, wherein the mass ratio of total monomers to 2cst base oil is 1:4-1:19 when preparing I/B, the addition amount of alkyl lithium is 1X 10 -3 -1×10 - 2 mol/100g total monomers, the mass ratio between I and B is 3:7-7:3, and the mass ratio between I/B and S is 98:2-90:10; B, after obtaining an I/B-S two-block polymer, adding a coupling agent into the system to react at 20-90 ℃, and adding isopropanol into the system to terminate the coupling reaction when the conversion rate of the coupling agent exceeds 95%, thereby obtaining a base gum, namely a star-shaped block copolymer (I/B-S) n -C, wherein the mol ratio of the coupling agent to the alkyl lithium is 3:1-20:1, and the mol ratio of the isopropanol to the alkyl lithium is 1:1; Adding a hydrogenation catalyst into the base oil solution of the base gum, uniformly mixing, introducing hydrogenation, and carrying out hydrogenation reaction at the temperature of 40-90 ℃ and the hydrogen pressure of 1.0-6.0 MPa; The base oil solvent is one or two of base oils of class I, class II, class III and class IV with viscosity of 1-5 cst.
2. 2. The process according to claim 1, wherein the alkyllithium has the formula RLi, R is a hydrocarbon group having 4 to 20 carbon atoms, and the coupling agent is an epoxy compound or a diene compound.
3. 3. The process of claim 1 wherein the hydrogenation catalyst is a main catalyst and a cocatalyst, the main catalyst is a nickel salt, and the cocatalyst is an aluminum alkyl.
4. 4. A process according to claim 3, wherein the molar ratio of aluminum alkyl to nickel salt is from 2:1 to 6:1.
5. 5. The process according to claim 1, wherein the hydrogenation reaction is carried out such that the degree of hydrogenation of the diolefin unsaturated double bonds in the copolymer is more than 95%, the degree of hydrogenation of the aromatic unsaturated bonds is less than 5% and the catalyst residue is less than 30ppm.

Description

Viscosity index improver concentrate prepared in situ in low-viscosity base oil and preparation method thereof Technical Field The invention relates to a viscosity index improver concentrated solution applied to lubricating oil, in particular to a viscosity index improver concentrated solution (concentrated solution of star hydrogenated styrene (S) -isoprene (I) -butadiene (B) terpolymer viscosity index improver) prepared in situ in low-viscosity base oil and a preparation method thereof. Background The viscosity index improver with controllable structure, narrow molecular weight distribution and various topological structures can be prepared by adopting a method of combining anionic living polymerization and hydrogenation modification. Among them, the star-shaped hydrogenated SIBR type viscosity index improver is the best known, and the SV260 of RunYing company is the highest market share of the product. The polymer arm of the star-shaped viscosity index improver described in U.S. patent No.4116917 is a hydrogenated poly (butadiene/isoprene) graded arm, the preparation process uses cyclohexane as a solvent, styrene, butadiene and isoprene as monomers, n-butyllithium as an initiator, divinylbenzene as a coupling agent for anionic polymerization and coupling, nickel naphthenate as a main catalyst and triisobutylaluminum as a cocatalyst are used for hydrogenation modification of the star-shaped polymer after termination of the reaction, so as to obtain a saturated star-shaped polymer, and the star-shaped viscosity index improver dry gel is obtained through catalyst removal, solvent flash evaporation, gel solution condensation, solvent recovery and product drying. Commercial products include both dry gelatin and concentrate forms. In the preparation method, the steps of solvent flash evaporation, glue solution condensation, solvent recovery, product drying and dry glue dissolution in base oil and the like are complex in operation, so that the production period is prolonged, and the production cost is increased. Disclosure of Invention The invention aims to provide a viscosity index improver concentrated solution prepared in situ in low-viscosity base oil and a preparation method thereof. In order to achieve the above purpose, the technical scheme is as follows: a method for preparing a viscosity index improver concentrated solution in situ in low-viscosity base oil comprises the steps of polymerizing, hydrogenating and deashing monomers in the low-viscosity base oil at a concentration of 5-15 wt% of the system to directly obtain the viscosity index improver concentrated solution. Further, in the present description, Adding isoprene and butadiene into base oil, adding an alkyl lithium initiator to initiate polymerization at 20-90 ℃, reacting to obtain isoprene and butadiene random copolymer I/B when the conversion rate of the isoprene and the butadiene exceeds 95%, adding styrene (S), continuing to react at 20-90 ℃ until the conversion rate of the styrene exceeds 95% to obtain I/B-S two-block polymer, wherein the mass ratio of total monomers to 2cst base oil is 1:4-1:19 when preparing I/B, the addition amount of alkyl lithium is 1X 10 -3-1×10-2 mol/100g total monomers, the mass ratio between I and B is 3:7-7:3, and the mass ratio between I/B and S is 98:2-90:10; In the steps, the distribution of monomers in the isoprene and butadiene copolymer I/B is controlled by adding a structure regulator, the random copolymer is obtained by adding the structure regulator, the addition amount is generally that the molar ratio of THF to Li is between 10:1 and 50:1, the structure regulator is tetrahydrofuran, and meanwhile, the gradual change copolymer I/B can be obtained without adding the structure regulator. B, after obtaining an I/B-S two-block polymer, adding a coupling agent into the system to react at 20-90 ℃, and adding isopropanol into the system to terminate the coupling reaction when the conversion rate of the coupling agent exceeds 95%, thereby obtaining a base gum, namely a star-shaped block copolymer (I/B-S) n -C, wherein the mol ratio of the coupling agent to the alkyl lithium is 3:1-20:1, and the mol ratio of the isopropanol to the alkyl lithium is 1:1; Adding a hydrogenation catalyst into the base oil solution of the base gum, uniformly mixing, introducing hydrogenation, performing hydrogenation reaction at the temperature of 40-90 ℃ and the hydrogen pressure of 1.0-6.0MPa, adding solid acid and hydrogen peroxide after the hydrogenation reaction is finished to separate the hydrogenation catalyst out in a solid form, and lowering catalyst waste residues on a high-speed centrifuge for layering and removing to obtain concentrated solution of the viscosity index improver. The base oil solvent is one or two of base oils of class I, class II, class III and class IV with viscosity of 1-5 cst. The molecular formula of the alkyl lithium is RLi, R is alkyl with 4-20 carbon atoms, preferably n-butyl lithium or sec-butyl