CN108003983B

CN108003983B - Lubricating oil composition for diesel engine and preparation method thereof

Info

Publication number: CN108003983B
Application number: CN201610959653.1A
Authority: CN
Inventors: 徐杰; 张耀; 段庆华; 武志强; 张倩; 刘依农; 夏青虹; 张峰; 孙文斌
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2016-10-27
Filing date: 2016-10-27
Publication date: 2020-05-19
Anticipated expiration: 2036-10-27
Also published as: CN108003983A

Abstract

The invention provides a lubricating oil composition for a diesel engine and a preparation method thereof. The lubricating oil composition for the diesel engine comprises the following components: a is more than acrylate copolymer pour point depressant, which contains a plurality of copolymers obtained by copolymerizing a first monomer shown in formula (1) and a second monomer shown in formula (2) according to proportional gradient change;

Description

Lubricating oil composition for diesel engine and preparation method thereof

Technical Field

The present invention relates to a lubricating oil composition, and particularly to a lubricating oil composition suitable for diesel engines.

Background

The requirements of environmental protection and energy conservation promote the development of engine technology and the continuous upgrading and updating of diesel engine oil, and the performance requirements of oil products in the aspects of soot dispersion, oxidation resistance, wear resistance, high-temperature cleanness and the like are higher and higher. The highest quality grade of diesel engine lubricating oil on the market today is the CJ-4 grade established by the American Petroleum Institute (API).

In the past 20 years, in order to avoid catastrophic accidents caused by vehicle starting failure in winter, low-temperature pumpability is always an important index of engine oil, but only new oil is initially used. The continuous progress of the engine increases the anti-oxidation load of the oil product, and the soot load of the diesel engine oil continuously increases, so that the low-temperature pumping performance of the lubricating oil is unqualified at the later stage of the actual service life, and the accidents of vehicle burning and the like occur. These problems have raised concerns and raised requirements in the industry for cryogenic pumping performance of lubricating oils. For diesel engine oil, the CI-4 specification of 2002 specifies that the dynamic viscosity of MRV-TP1 of waste oil at-20 ℃ in 75h of Mack T-10A engine test is not more than 25000mPa & s, and the waste oil has no yield stress. CJ-4 specification coming out in 2006 stipulates that the MRV-TP1 dynamic viscosity of waste oil at-20 ℃ in 180h of Mack T-11A engine test is not more than 25000mPa & s, and no yield stress exists.

Pour point depressants are used to improve the low temperature properties of oils in oil formulation development. The pour point depressant for the commercially available lubricating oil has multiple types, wherein the (methyl) acrylate copolymer has super-strong adaptability in structure, composition and preparation process, has excellent pour point depressing performance in base oil, and is an important component of the pour point depressant market at home and abroad. It is generally believed that the alkyl side chain of the poly (meth) acrylate pour point depressant has a structure similar to that of paraffin in oil products, and inhibits wax crystals from forming a network structure through adsorption or eutectic crystallization, thereby achieving the purpose of improving the low-temperature performance of base oil. Various poly (meth) acrylate pour point depressants have been developed.

For example, US6458749 discloses improving the low temperature fluidity of lubricating oil compositions by combining a low molecular weight copolymer containing 0-25 wt.% of (C16-C24) alkyl (meth) acrylate with a high molecular weight copolymer containing 25-70 wt.% of (C16-C24) alkyl (meth) acrylate. U.S. Pat. No. 5,5368761 discloses a random copolymer prepared by copolymerizing 15 to 67 mol% of (C8-C15) alkyl (meth) acrylate, 3 to 40 mol% of (C16-C24) alkyl (meth) acrylate, and 30 to 65 mol% of (C1-C4) alkyl (meth) acrylate. CN101535355A discloses a polyalkylmethacrylate copolymer containing 60-96% by weight of a C12-C16 alkyl methacrylate and about 4-40% by weight of a C18-C30 alkyl methacrylate. CN101679902A discloses a pour point depressant for lubricating oils, which is composed of a mixture of an alkyl (meth) acrylate copolymer (a) composed of an alkyl (meth) acrylate having an alkyl group with an average carbon number (CA) in the range of 12.5 to 13.8 and an alkyl (meth) acrylate copolymer (B) composed of an alkyl (meth) acrylate having an alkyl group with an average carbon number (CB) in the range of 13.9 to 15.5. US6403745 discloses a gradient copolymer of ethylenically unsaturated monomers comprising from 0 to 40% by weight of (C1-C5) alkyl (meth) acrylate, from 10 to 98% by weight of (C6-C15) alkyl (meth) acrylate and from 0 to 80% by weight of (C16-C30) alkyl (meth) acrylate, which gradient copolymer is obtained by polymerizing the polymerized monomers in two stages, in particular by reacting a portion of the monomer or monomer mixture for a period of time and then adding the remaining portion of the monomer or monomer mixture to continue the reaction. WO 2015/110340 discloses a mixture of two alkyl (meth) acrylate copolymers which improves the low temperature pumpability of the aged engine oil.

The function of the pour point depressant in the fully formulated engine oil is influenced by the viscosity index improver and the functional additive, and the performance of various aspects of the oil is balanced through compounding of the additives, so that the increasingly strict low-temperature performance requirements of the oil are met, and the pour point depressant is very necessary.

Disclosure of Invention

The invention provides a lubricating oil composition for a diesel engine and a preparation method thereof.

The lubricating oil composition for diesel engines of the present invention comprises the following components:

a is more than acrylate copolymer pour point depressant, which contains a plurality of copolymers obtained by copolymerizing a first monomer shown in formula (1) and a second monomer shown in formula (2) according to proportional gradient change;

wherein R is₁Is C₆-C₁₈Alkyl of R₂Is C₈-C₂₀The alkyl group of (1), R in the first monomer₁Average value of (2)

Less than R in the second monomer₂Average value of (2)

And is

R₃And R₄Each independently hydrogen or methyl;

b is greater than viscosity index improver;

c > dispersing agent;

d > a mixture of an alkylsalicylate and a sulfurized alkylphenate;

e > zinc dialkyldithiophosphate;

f > dialkyldithiocarbamate;

g is more than auxiliary antioxidant;

h is more than the balance of lubricating oil base oil.

Specifically, the lubricating oil composition of the present invention comprises the following components:

Less than R in the second monomer₂Average value of (2)

And is

R₃And R₄Each independently hydrogen or methyl.

The preparation method of the acrylate copolymer pour point depressant comprises the following steps:

(a) dropping a first mixture containing a first monomer represented by formula (1), an initiator and a molecular weight regulator into a reactor filled with diluent oil under the condition of olefin polymerization, wherein the initial dropping rate of the first mixture is X₀(ii) a The dropping rate X of the first mixture at the early stage of the dropping₁-X_n/2Maintaining constant, increasing or decreasing, and the dropping speed X in the middle stage of dropping_n/2Satisfy 4/5X₀<X_n/2<5/4X₀Addition rate X at the late stage of addition_n/2-X_nDecreasing, dropping rate X when dropping is over_nSatisfy 1/10X_n/2<X_n<4/5X_n/2(ii) a The total dropping time of the first mixture is t 1;

(b) dropping a second mixture containing a second monomer represented by the formula (2), an initiator and a molecular weight regulator into the reactor while dropping the first mixtureAnd the initial dropping rate of the second mixture is Y₀(ii) a The dropping rate Y of the second mixture at the early stage of dropping₁-Y_n/2Increasing, the dropping rate Y in the middle stage of dropping_n/2Satisfy Y₀<Y_n/2<5Y₀The dropping rate Y at the late stage of dropping_n/2-Y_nMaintaining constant, increasing or decreasing, the dropping rate Y at the end of the dropping_nSatisfies 4/5Y_n/2<Y_n<6/5Y_n/2(ii) a The total drop time of the second mixture is t2, and t1 ═ t 2;

Less than R in the second monomer₂Average value of (2)

And is

Preference is given to

Preferably sigma R₂＝14.0-15.6；R₃And R₄Each independently hydrogen or methyl.

The acrylate copolymer provided by the invention can enable the lubricating oil composition to have excellent low-temperature performance, and particularly can improve the low-temperature pumping performance of the aged soot-containing lubricating oil.

The method for preparing the acrylate copolymer pour point depressant of the present invention will be described in detail in the following section.

The component A accounts for 0.01 to 2 percent of the total mass of the lubricating oil composition, and preferably 0.05 to 1.5 percent.

B > the viscosity index improver is selected from the group consisting of amorphous ethylene propylene copolymers, polymethacrylates, polyalkylmethacrylates, methacrylate copolymers, copolymers of styrene and acrylates, partially hydrogenated copolymers of styrene/isoprene, styrene/butadiene, isoprene/butadiene, and partially hydrogenated homopolymers of butadiene and isoprene, isoprene/divinylbenzene.

By amorphous ethylene propylene copolymer is meant amorphous or semi-crystalline ethylene propylene copolymers, typically having an ethylene content of from 25 Wt% to 60 Wt%, and the amorphous ethylene propylene copolymers selected for use in the present invention have a crystallinity of from 0% to 2.5%, preferably from 0% to 2%, more preferably from 0% to 1.5%.

Component B viscosity index improvers are commonly available under the trade designations LZ7070, LZ7065, LZ7067, LZ7077 from Lubrizol, SV260, SV261 from Infineum, and the like.

The component B accounts for 0.1 to 25 percent of the total mass of the lubricating oil composition, and preferably 0.5 to 20 percent of the total mass of the lubricating oil composition.

The dispersant C is selected from polyisobutylene succinimide ashless dispersant and/or antioxidant polyisobutylene succinimide ashless dispersant.

The ashless dispersant of polyisobutylene succinimide may be selected from one or more of mono-polyisobutylene succinimide, di-polyisobutylene succinimide, polyisobutylene succinimide and high molecular polyisobutylene succinimide, wherein the number average molecular weight of Polyisobutylene (PIB) moiety is 800-4000, preferably 900-3000, preferably 1000-2400, T151, T152 from southern additive Co., Ltd, T161 from Suzhou special oil product factory, T155, T161A, T161B from additives factory of petrochemical company, LZL157 from Lobonun additive Co., Ltd, LZ6418, LZ6420 from Lubrizol Corporation, Hitec646 from Afton Corporation, etc.

The antioxidant polyisobutylene succinimide ashless dispersant is obtained by connecting nitrogen atoms on polyolefin succinimide with benzene rings in methoxyphenol through alkylene groups, and the preparation method comprises the steps of adding aldehyde into a mixture of the methoxyphenol and the polyene polyamine to react to obtain condensed amine, and then reacting the condensed amine with polyolefin succinic anhydride. The polyolefin is preferably C2-C4 monoolefin copolymerization or homopolymer, and can be polyisobutylene, atactic polypropylene, ethylene-propylene copolymer, and its number average molecular weight is 850-5000, preferably 1000-4000; the methoxyphenol is selected from one or more of p-methoxyphenol, o-methoxyphenol and m-methoxyphenol; the aldehyde is selected from one or more of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde and benzaldehyde, and preferably formaldehyde and/or paraformaldehyde. The antioxidant polyisobutylene succinimide ashless dispersant can be prepared by the method of patent CN 00107484.9.

The component C accounts for 0.5 to 15 percent of the total mass of the lubricating oil composition, and preferably 1 to 12 percent.

D > a mixture of an alkyl salicylate and a sulfurized alkylphenate, preferably a mixture of calcium alkyl salicylate and calcium sulfurized alkylphenate, more preferably a mixture of high-base-number calcium alkyl salicylate having a base number of (200-450) mgKOH/g and medium-base-number calcium sulfurized alkylphenate having a base number of (100-200) mgKOH/g, the preferred mass ratio between the two being 0.2: 1 to 4: 1. Component D may be selected from LZL109B, LZL112, LZL115A, LZL115B, manufactured by Lubrium additives Ltd, C9375, C9012, C9391, C9394, manufactured by OSCA, SAP007 manufactured by Shell, LZ6499, LZ6500 manufactured by Lubrizol Corporation, OLOA219 manufactured by Chevron Oronite Company.

The component D accounts for 0.5 to 8 percent of the total mass of the lubricating oil composition, and preferably 1 to 6 percent.

Alkyl groups in the E > zinc dialkyldithiophosphate are alkyl groups containing 2 to 12 carbon atoms, preferably alkyl groups containing 2 to 8 carbon atoms, including, but not limited to, one or more of ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-octyl, 2-ethylhexyl, cyclohexyl, and methylcyclopentyl.

The zinc dialkyldithiophosphate may be selected from, but not limited to, T202 and T203 from south oil additives limited without tin, T202 and T203 from additive plants from petrochemical division, ca, primary-secondary alkyl T204 and secondary alkyl T205, LZ1371 and LZ1375 from Lubrizol, C9417, C9425 and C9426 from infinium, Hitec7169 and Hitec1656 from Afton, and the like.

The addition amount of the component E in the lubricating oil composition is preferably not more than 0.12% by mass of the phosphorus element, and preferably 0.07-0.12%.

The alkyl group in the F > dialkyldithiocarbamate is an alkyl group having 2 to 12 carbon atoms, preferably an alkyl group having 2 to 8 carbon atoms, and may be an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a n-pentyl group, an isopentyl group, a n-hexyl group, an isohexyl group, a n-octyl group, or a 2-ethylhexyl group.

The dialkyl dithiocarbamates may be selected from T323 available from New Petroleum additives, Inc., Vanderbilt, Inc., 7723, and the like.

Component F accounts for 0.02-5% of the total mass of the lubricating oil composition, preferably 0.05-2%, and most preferably 0.1-0.5%.

G & gt is one or more of phenolic antioxidant, amine antioxidant, phenolic ester antioxidant and sulfophenolic ester antioxidant.

the phenolic antioxidant can be one or more of 2, 6-di-tert-butyl- α -dimethylamino-p-cresol, 2, 6-di-tert-butyl-p-cresol, 4-methylenebis (2, 6-di-tert-butylphenol) and 2, 6-di-tert-butyl-4-alkoxy phenol.

the amine-type antioxidant may be alkylated anilines, alkylated diphenylamines having an alkyl carbon number of C2-C12, preferably oil-soluble dialkyldiphenylamines such as dibutyldiphenylamine, dioctyldiphenylamine, dinonyldiphenylamine, butyloctyldiphenylamine, phenylnaphthylamine, more preferably dinonyldiphenylamine, and alkylated diphenylamines commercially available such as IRGANOX L-01 and IRGANOX L-57 from BASF corporation, Beijing, Xingpu Fine chemical engineering development company, T534 from Lanzhou Luborun additives, LZ5150A from Lanzhou Lubornlet, VANLUBE NA, VANLUBE 961, dioctyldiphenylamine VANLUBE 81 from Rhein Chemie corporation, P' -diisooctyldiphenylamine RC7001, MTN 438L from Cheura corporation, and the like.

The phenolic ester antioxidant is preferably hydroxy phenyl carboxylic ester with molecular weight of 200-500, such as IRGANOX L-135 from BASF corporation in Germany and T512 from Fine chemical engineering technology development corporation in Beijing Xingpo.

The thiophenol ester antioxidant can be 2,2' -thiobis [ ethyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], such as antioxidant 1035 from Sichuan Yongsu chemical Co., Ltd, and IRGANOX L115 from BASF.

Component G is preferably a phenolic ester type antioxidant.

The component G accounts for 0.1 to 6 percent of the total mass of the lubricating oil composition, and preferably 0.2 to 4 percent.

H > the balance of lubricating base oil, selected from one or more of API group I, II, III, IV and V base oils, preferably API group II base oil and/or API group III base oil.

The following is a detailed description of specific embodiments of component A of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The acrylate copolymer provided by the invention contains a plurality of copolymers obtained by copolymerizing a first monomer shown in a formula (1) and a second monomer shown in a formula (2) according to a proportional gradient change;

Less than R in the second monomer₂Average value of (2)

And is

Preference is given to

The acrylate copolymer provided by the invention contains a plurality of copolymers obtained by copolymerizing a first monomer shown in a formula (1) and a second monomer shown in a formula (2) according to a gradient change of proportion, namely, the acrylate copolymer has a gradient molecular structure. The gradient molecular structure means that the acrylate copolymer is composed of P₁、P₂、P₃···P_n-1、P_nComposition, n is more than or equal to 3, wherein, P₁、P₂、P₃···P_n-1、P_nBoth of which are copolymers obtained by copolymerizing a first monomer represented by the formula (1) and a second monomer represented by the formula (2), P₁Wherein the relative ratio of the content of the structural unit derived from the first monomer to the content of the structural unit derived from the second monomer is X₁:Y₁；P₂-P_nAt P₁Based on the content (X) of the structural unit derived from the first monomer in the copolymer structure₂-X_n) Continuously decreasing in content of structural units derived from the second monomer (Y)₂-Y_n) Is increasing, i.e. X₁:Y₁＞X₂:Y₂＞X₃:Y₃＞···＞X_n-1:Y_n-1＞X_n:Y_n。

The content of the structural units derived from the first monomer and the second monomer in the acrylate-based copolymer is not particularly limited, and preferably, the content of the structural units derived from the first monomer is 10 to 90% by weight, and the content of the structural units derived from the second monomer is 10 to 90% by weight; more preferably, the content of the structural unit derived from the first monomer is 25 to 75% by weight, and the content of the structural unit derived from the second monomer is 25 to 75% by weight. In the present invention, the content of the structural units derived from the first monomer and the second monomer can be calculated by the amount of the first monomer and the second monomer added in the process of preparing the acrylate-based copolymer. It should be noted that, in order to obtain the acrylate-based copolymer having a gradient molecular structure, the first monomer and the second monomer are generally separately fed, and therefore, although the first monomer and the second monomer contain partially overlapping monomers, the content of the structural unit derived from the first monomer and the content of the structural unit derived from the second monomer can be distinguished according to the feeding manner.

In the first monomer, the C₆-C₁₈Examples of alkyl groups of (a) include, but are not limited to: hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, or eicosyl. Specifically, the first monomer may be selected from the group consisting of hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, octyl acrylate, octyl methacrylate, nonyl acrylate, nonyl methacrylate, decyl acrylate, decyl methacrylate, undecyl acrylate, undecyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, tetradecyl acrylate, tetradecyl methacrylate, pentadecyl acrylate, pentadecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, heptadecyl acrylate, heptadecyl methacrylate, acrylic acid, heptadecyl ester, acrylic acidOne or more of octadecyl ester and octadecyl methacrylate. Preferably, the first monomer is a monomer containing (meth) acrylic acid C₆Alkyl esters, (meth) acrylic acid C₈Alkyl esters, (meth) acrylic acid C₁₀Alkyl esters, (meth) acrylic acid C₁₂Alkyl esters, (meth) acrylic acid C₁₄Alkyl esters, (meth) acrylic acid C₁₆Alkyl esters, (meth) acrylic acid C₁₈At least one alkyl ester. Preferably, the first monomer contains both (meth) acrylic acid C₁₂Alkyl esters and (meth) acrylic acid C₁₄An alkyl ester. More preferably, the first monomer is (meth) acrylic acid C₁₀Alkyl esters, (meth) acrylic acid C₁₂Alkyl esters, (meth) acrylic acid C₁₄Alkyl esters, (meth) acrylic acid C₁₆Alkyl esters and (meth) acrylic acid C₁₈A mixture of alkyl esters; or, the first monomer is (meth) acrylic acid C₈Alkyl esters, (meth) acrylic acid C₁₀Alkyl esters, (meth) acrylic acid C₁₂Alkyl esters and (meth) acrylic acid C₁₄A mixture of alkyl esters; or, the first monomer is (meth) acrylic acid C₁₂Alkyl esters, (meth) acrylic acid C₁₄Alkyl esters, (meth) acrylic acid C₁₆Alkyl esters and (meth) acrylic acid C₁₈A mixture of alkyl esters.

The first monomer comprises (meth) acrylic acid ester having an average number of carbon atoms in the alkyl side chain thereof

More preferably satisfies

In the second monomer, the C₈-C₂₀Examples of alkyl groups of (a) include, but are not limited to: octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl or eicosyl. In particular, the second monomer may be selected from octyl acrylate, octyl methacrylateOne or more of ester, nonyl acrylate, nonyl methacrylate, decyl acrylate, decyl methacrylate, undecyl acrylate, undecyl methacrylate, dodecyl acrylate, dodecyl methacrylate, tridecyl acrylate, tridecyl methacrylate, tetradecyl acrylate, tetradecyl methacrylate, pentadecyl acrylate, pentadecyl methacrylate, hexadecyl acrylate, hexadecyl methacrylate, heptadecyl acrylate, heptadecyl methacrylate, octadecyl acrylate, octadecyl methacrylate, nonadecyl acrylate, nonadecyl methacrylate, eicosyl acrylate, and eicosyl methacrylate. Preferably, the second monomer preferably has C₈-C₂₀The mixture of alkyl-substituted (meth) acrylates more preferably contains C (meth) acrylic acid₈Alkyl esters, (meth) acrylic acid C₁₀Alkyl esters, (meth) acrylic acid C₁₂Alkyl esters, (meth) acrylic acid C₁₄Alkyl esters, (meth) acrylic acid C₁₆Alkyl esters, (meth) acrylic acid C₁₈Alkyl esters, (meth) acrylic acid C₂₀At least one alkyl ester. Preferably, the second monomer contains both (meth) acrylic acid C₁₄Alkyl esters, (meth) acrylic acid C₁₆Alkyl esters, (meth) acrylic acid C₁₈Alkyl esters and (meth) acrylic acid C₂₀An alkyl ester. More preferably, the second monomer is (meth) acrylic acid C₁₄Alkyl esters, (meth) acrylic acid C₁₆Alkyl esters, (meth) acrylic acid C₁₈Alkyl esters, (meth) acrylic acid C₂₀A mixture of alkyl esters; or the second monomer is (methyl) acrylic acid C₁₀Alkyl esters, (meth) acrylic acid C₁₂Alkyl esters, (meth) acrylic acid C₁₄Alkyl esters, (meth) acrylic acid C₁₆Alkyl esters, (meth) acrylic acid C₁₈Alkyl esters and (meth) acrylic acid C₂₀A mixture of alkyl esters.

The second monomer comprises a (meth) acrylate having an alkyl side chain with an average number of carbon atoms satisfying

More preferably satisfies

The first monomer and the second monomer can be obtained commercially, or can be prepared by various methods, for example, by an esterification reaction of (meth) acrylic acid and alcohol, or by an exchange reaction of a low carbon ester of (meth) acrylic acid and alcohol, and are known to those skilled in the art and will not be described herein.

The acrylate copolymer can be produced by various methods known to those skilled in the art, and can be produced, for example, by any one of bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and the like, preferably by solution polymerization.

According to a preferred embodiment of the present invention, the acrylate-based copolymer is prepared according to a method comprising the steps of:

(b) dropping a second mixture containing a second monomer represented by the formula (2), an initiator and a molecular weight regulator into the reactor at the same time as dropping the first mixture, wherein the initial dropping rate of the second mixture is Y₀(ii) a The dropping rate Y of the second mixture at the early stage of dropping₁-Y_n/2Increasing, the dropping rate Y in the middle stage of dropping_n/2Satisfy Y₀<Y_n/2<5Y₀The dropping rate Y at the late stage of dropping_n/2-Y_nMaintaining constant, increasing or decreasing, the dropping rate Y at the end of the dropping_nSatisfies 4/5Y_n/2<Y_n<6/5Y_n/2(ii) a The total drop time of the second mixture was t2, and t1 ═ t 2.

In the present invention, the term "the preliminary stage of dropping" means a period of time from the start of dropping of the material to half of the total dropping time; the term "mid-dropping stage" refers to a point in time that is half of the total dropping time; the term "late stage of addition" means a period from half of the total addition time to the completion of the addition of the materials. In other words, the early dropping stage t is 0 < t < 1/2t1, the middle dropping stage t is 1/2t1, and the late dropping stage t is 1/2t1 < t1, relative to the first mixture; and relative to the second mixture, the early dropping stage t is 0 < t < 1/2t2, the middle dropping stage t is 1/2t2, and the later dropping stage t is 1/2t2 < t 2.

When the acrylate copolymer is prepared by the method, the relative proportion of the first monomer in a polymerization system is gradually reduced and the relative proportion of the second monomer is gradually increased along with the lapse of time, and at the moment, the polymerization reaction is gradually changed into the copolymer containing less first monomer and more second monomer from the copolymerization of more first monomer and less second monomer, so that the copolymer P is obtained₁、P₂、P₃···P_n-1、P_nThe acrylic ester copolymer of (2) has a gradient molecular structure. The copolymer has a gradient molecular structure, which means that a monomer mixture constituting the copolymer is changed from one composition to another composition in a gradual gradient manner, namely, the content of a part of monomer structural units in the molecular structure of the copolymer is gradually reduced along with the increase of time, and the content of another part of monomer structural units in the molecular structure of the copolymer is gradually increased along with the increase of time.

Further, the first monomer may be used in an amount of 10 to 90% by weight, preferably 25 to 75% by weight, and the second monomer may be used in an amount of 10 to 90% by weight, preferably 25 to 75% by weight, based on the total amount of the first monomer and the second monomer.

In the preparation of the acrylate-based copolymer, the initial temperature of the olefin polymerization reaction may be generally 50 to 180 ℃, preferably 55 to 165 ℃, and most preferably 60 to 150 ℃. In addition, the total dropping time t1 and t2 may be 1 to 12 hours, preferably 1.5 to 10 hours.

According to the present invention, in order to further facilitate the improvement of the monomer conversion rate, preferably, the method for preparing the acrylate-based copolymer further comprises continuing the reaction for 0.5 to 2 hours after the end of the dropwise addition of the first mixture and the second mixture, then supplementing the initiator and the diluent oil, and then increasing the temperature to 100 to 150 ℃ to continue the reaction for 0.5 to 5 hours.

The amount of the initiator used in the present invention is not particularly limited, and for example, the amount of the initiator used in the entire polymerization process may be 0.01 to 2.5 parts by weight, preferably 0.05 to 2 parts by weight, and more preferably 0.1 to 1.5 parts by weight, relative to 100 parts by weight of the total amount of the first monomer and the second monomer. The weight ratio of the total amount of initiator used to the amount of added initiator in the first and second mixtures may be from 1 to 20:1, preferably from 2 to 10:1, more preferably from 2.5 to 7.5: 1. In addition, the initiator used in the first mixture and the second mixture and the additional initiator may be the same or different, and may be at least one of various existing radical initiators, such as azo initiators, peroxide initiators, and redox initiators, independently.

Wherein the azo initiator may be selected from one or more of dimethyl azobisisobutyrate, azobisisobutyramidine hydrochloride, azobisformamide, azobisisopropylimidazoline hydrochloride, azobisisobutyronitrile formamide, azobiscyclohexylcarbonitrile, azobiscyanovaleric acid, azobisdiisopropylimidazoline, azobisisobutyronitrile, azobisisovaleronitrile, and azobisisoheptonitrile.

The peroxide initiator may be one or more selected from hydrogen peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, lauroyl peroxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide t-butyl peroxide, t-butyl peroxypivalate, cyclohexanone peroxide, methyl ethyl ketone peroxide, and diisopropyl peroxydicarbonate.

The redox initiator may be selected from one or more of sulfate-sulfite, persulfate-thiourea, persulfate-organic salt and ammonium persulfate-fatty amine. Wherein, the sulfate-sulfite can be selected from one or more of sodium sulfate-sodium sulfite, potassium sulfate-potassium sulfite and ammonium sulfate-ammonium sulfite; the persulfate-thiourea can be one or more selected from sodium persulfate-thiourea, potassium persulfate-thiourea and ammonium persulfate-thiourea; the persulfate-organic salt can be selected from one or more of sodium persulfate-potassium acetate, potassium persulfate-potassium acetate and ammonium persulfate-ammonium acetate; the ammonium persulfate-fatty amine may be selected from one or more of ammonium persulfate-N, N-tetramethylethylenediamine and ammonium persulfate-diethylamine.

The amount of the diluent oil used in the present invention is not particularly limited, and for example, the amount of the diluent oil used throughout the polymerization reaction may be 10 to 150 parts by weight, preferably 50 to 100 parts by weight, and more preferably 60 to 80 parts by weight, relative to 100 parts by weight of the total amount of the first monomer and the second monomer. The weight ratio of the amount of diluent oil used in the initial polymerization stage to the amount of additional diluent oil used may be in the range of 0.5 to 1.5:1, preferably 0.8 to 1.2: 1. The diluent oil in the initial polymerization stage may be the same as or different from the additional diluent oil, and may be, independently of each other, any of various conventional substances capable of diluting the viscosity of the acrylate-based copolymer and facilitating its addition and dispersion in subsequent applications, for example, at least one of diesel oil, kerosene, solvent oil, aromatic solvent, white oil, mineral oil base oil, synthetic oil, etc., preferably at least one of white oil, mineral oil base oil, synthetic oil, and most preferably mineral base oil. The diluent oil may be commercially available, for example, as a 100N diluent oil available from Dilongjie corporation. The diluent oil may or may not be separated from the acrylate copolymer after the polymerization reaction is completed.

The molecular weight regulators in the first and second mixtures may be the same or different in type and may each be a routine choice in the art, for example, may each independently be dodecyl mercaptan and/or 2-mercaptoethanol. In addition, the amount of the molecular weight regulator contained in the first mixture and the second mixture can be selected conventionally in the field, and is not described herein.

In order to overcome oxygen inhibition and obtain copolymerization products with larger molecular weight, the olefin polymerization reaction is preferably carried out in an inert atmosphere. The inert atmosphere refers to any gas or gas mixture that does not chemically react with the reactants and products, such as one or more of nitrogen, helium, and a gas from group zero of the periodic table of elements. The inert atmosphere may be maintained by introducing any one or a mixture of the above gases which do not chemically react with the reactants and the products into the reaction system.

In the present invention, the molecular weight of the acrylate copolymer is not particularly limited, and for example, the number average molecular weight of the acrylate copolymer may be 1 ten thousand to 100 ten thousand, preferably 1 ten thousand to 50 ten thousand, and more preferably 1 ten thousand to 10 ten thousand. In the present invention, the number average molecular weight is measured by Gel Permeation Chromatography (GPC) using polybutylmethacrylate as a standard, a sample concentration of 0.05mmol/L, and tetrahydrofuran as a solvent.

(a) dropping a first mixture containing a first monomer represented by formula (1), an initiator and a molecular weight regulator into a reactor filled with diluent oil under the condition of olefin polymerization, wherein the initial dropping rate of the first mixture is X₀(ii) a The dropping rate X of the first mixture at the early stage of the dropping₁-X_n/2Maintaining constant, increasing or decreasing, and the dropping speed X in the middle stage of dropping_n/2Satisfies 4/5X₀<X_n/2<5/4X₀Addition rate X at the late stage of addition_n/2-X_nDecreasing, dropping rate X when dropping is over_nSatisfy 1/10X_n/2<X_n<4/5X_n/2(ii) a The total dropping time of the first mixture is t 1;

(b) dropping a second mixture containing a second monomer represented by the formula (2), an initiator and a molecular weight regulator into the reactor at the same time as dropping the first mixture, wherein the initial dropping rate of the second mixture is Y₀(ii) a The dropping rate Y of the second mixture at the early stage of dropping₁-Y_n/2Increasing, the dropping rate Y in the middle stage of dropping_n/2Satisfy Y₀<Y_n/2<5Y₀The dropping rate Y at the late stage of dropping_n/2-Y_nMaintaining constant, increasing or decreasing, the dropping rate Y at the end of the dropping_nSatisfies 4/5Y_n/2<Y_n<6/5Y_n/2(ii) a The total drop time of the second mixture is t2, and t1 ═ t 2;

Less than R in the second monomer₂Average value of (2)

And is

Preference is given to

The olefin polymerization reaction may be initiated at a temperature generally ranging from 50 to 180 deg.C, preferably from 55 to 165 deg.C, and most preferably from 60 to 150 deg.C. In addition, the total dropping time t1 and t2 may be 1 to 12 hours, preferably 1.5 to 10 hours.

Preferably, the preparation method further comprises the steps of continuing the reaction for 0.5 to 2 hours after the dropwise addition of the first mixture and the second mixture is finished, then adding the initiator and the diluent oil, and then raising the temperature to 100 to 150 ℃ for continuing the reaction for 0.5 to 5 hours.

The specific types and amounts of the first monomer, the second monomer, the diluent oil, the initiator, the molecular weight regulator and other conditions have been described above, and are not described herein.

The acrylate copolymer provided by the invention is particularly suitable for being used as pour point depressant of base oil from different sources, including API I mineral base oil, API II/III hydrogenated base oil and lubricating oil containing API I and API II/III base oil. Wherein the lubricating oil containing API group I and API group II/III base oils contains at least one of API group IV synthetic oils, API group V synthetic oils, GTL synthetic base oils, and the like, in addition to the API group I/API group II base oils.

The acrylate copolymer provided by the invention has excellent pour point depressing effect, and particularly for base oil with complex composition, the distribution and the side chain structure of the acrylate copolymer can be quantitatively matched with paraffin in the base oil, so that the pour point depressing efficiency is obviously improved.

The acrylate copolymer provided by the invention can be used alone or mixed with other lubricating oil pour point depressants to improve the low-temperature performance of the base oil. In particular applications, pour point depressants are generally added in an amount of from 0.01 to 2% by weight of the base oil, preferably from 0.05 to 1.5% by weight of the base oil, more preferably from 0.1 to 1% by weight of the base oil.

The acrylate copolymer provided by the invention is compounded with other additives and base oil for use, so that the lubricating oil composition has excellent low-temperature performance, and particularly the low-temperature pumping performance of the aged soot-containing lubricating oil can be improved.

The lubricating oil composition of the present invention can be prepared by the following method: the additives are respectively added into the lubricating oil base oil, or the components are mixed to prepare a concentrate which is then added into the lubricating oil base oil to be mixed and stirred, wherein the mixing and stirring temperature is between 40 ℃ and 90 ℃, and the time is between 1h and 6 h.

The lubricating oil composition of the present invention has excellent low temperature performance and low temperature pumping performance of aged soot-containing oil. Calculated by mass fraction, the composition of the invention has the phosphorus content of not more than 0.12 percent, the sulfur content of not more than 0.4 percent and the sulfated ash content of not more than 1 percent, and can meet the requirements of CJ-4 grade high-performance diesel engine lubricating oil.

Detailed Description

The present invention will be described in detail below by way of examples.

In the following examples and comparative examples, the contents of the copolymer and the diluent oil and the contents of the respective structural units in the copolymer were calculated from the charged amounts.

Example 1

This example is provided to illustrate the acrylate based copolymer pour point depressant and the method of making the same.

113kg of diluent oil (from Doxolone, 100N, same below) was charged into a mechanically stirred reactor under nitrogen, heated to 83-91 ℃ and 270kg of the first monomer [ decyl methacrylate/dodecyl methacrylate/tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate (C) was introduced at 50 kg/hr at A feed inlet₁₀28% by weight, C₁₂32% by weight, C₁₄28% by weight, C₁₆8% by weight, C₁₈4% by weight),

a mixture of 1.35kg of benzoyl peroxide and 1.08kg of dodecyl mercaptan was added dropwise to the reaction vessel, the feed was stabilized for 3 hours, and the rate of addition was then linearly reducedSo that when the total feed time was to 6 hours, the flow rate was reduced to 30 kg/hour. 150kg of a second monomer [ tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate/eicosyl methacrylate (C) was simultaneously added dropwise at an initial rate of 10 kg/hr at the feed inlet of B₁₄38% by weight, C₁₆20% by weight, C₁₈25% by weight, C₂₀When the weight percentage is equal to 17 percent,

a mixture of 0.75kg of benzoyl peroxide and 0.6kg of dodecyl mercaptan was added dropwise to the reaction vessel, and the flow rate of the pump at feed port B was set to a linear increase so that when the total feed time was 3 hours, the flow rate was increased to 30 kg/hour, and then the flow rate was maintained to feed for 3 hours. A. And when the dropwise adding of the feed inlets B is finished, continuously keeping the reaction kettle at 95 ℃ for 1 hour, then adding 0.3kg of benzoyl peroxide and 113kg of diluent oil, raising the temperature to 103 ℃ and keeping the temperature for 2 hours to finish the reaction to obtain a pour point depressant J1, wherein the monomer conversion rate of the pour point depressant J1 is 99.1%, and the number average molecular weight is 40120. Further, the pour point depressant J1 contained a copolymer containing 64.3% by weight of a structural unit derived from the monomer represented by formula (1) and 35.7% by weight of a structural unit derived from the monomer represented by formula (2).

Example 2

113kg of diluent oil were introduced into a mechanically stirred reactor under nitrogen, heated to 83-91 ℃ and 171kg of a first monomer [ octyl methacrylate/decyl methacrylate/dodecyl methacrylate/tetradecyl methacrylate (C) was introduced into the feed A at an initial rate of 40 kg/h₈12% by weight, C₁₀15% by weight, C₁₂48% by weight, C₁₄25% by weight),

a mixture of 0.9kg of benzoyl peroxide and 0.7kg of dodecyl mercaptan was added dropwise to the reaction vesselFollowed by a linear slow decrease such that the flow rate decreases to 32 kg/hour when the total feed time is 3 hours, followed by a linear fast decrease such that the flow rate decreases to 10 kg/hour when the total feed time is 6 hours. 255kg of a second monomer [ tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate/eicosyl methacrylate (C14: 38% by weight, C) was simultaneously added dropwise at an initial rate of 20 kg/h at the feed inlet B₁₆20% by weight, C₁₈25% by weight, C₂₀When the weight percentage is equal to 17 percent,

a mixture of 0.9kg of benzoyl peroxide and 0.7kg of dodecyl mercaptan was added dropwise to the reaction vessel, and the flow rate of the pump at feed port B was set to a linear increase so that when the total feed time was 3 hours, the flow rate was increased to 50 kg/hour, and then the flow rate was maintained to feed for 3 hours. A. And when the feed inlets B are all dripped, continuously keeping the reaction kettle at 95 ℃ for 1 hour, then adding 0.3kg of benzoyl peroxide and 113kg of diluent oil, raising the temperature to 103 ℃ and keeping the temperature for 2 hours to finish the reaction to obtain a pour point depressant J2, wherein the monomer conversion rate of the pour point depressant J2 is 99.4%, and the number average molecular weight is 41702. Further, the copolymer pour point depressant J2 contained a copolymer containing 40.0% by weight of a structural unit derived from the monomer represented by formula (1) and 60.0% by weight of a structural unit derived from the monomer represented by formula (2).

Comparative example 1

A pour point depressant was prepared as in example 1, except that the first monomer and the second monomer were mixed well and then added dropwise to the reaction system at a constant rate, specifically:

under the protection of nitrogen, 113kg of diluent oil was added to a reaction kettle equipped with a mechanical stirrer, heated to 83-91 ℃, and 270kg of a first monomer [ decyl methacrylate/dodecyl methacrylate/tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate (C)₁₀28% by weight, C₁₂32% by weight, C₁₄28% by weight, C₁₆8 wt%, C18-4 wt%),

150kg of a second monomer [ tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate/eicosyl methacrylate (C)₁₄38% by weight, C₁₆20% by weight, C₁₈25% by weight, C₂₀When the weight percentage is equal to 17 percent,

a mixture of 2.1kg of benzoyl peroxide and 1.68kg of dodecyl mercaptan is added dropwise into a reaction kettle at a constant rate of 70 kg/h, the dropwise addition time is 6 hours, when the dropwise addition is finished, the reaction kettle is kept at 95 ℃ for 1 hour, then 0.3kg of benzoyl peroxide and 113kg of diluent oil are added, the reaction is finished after the temperature is increased to 103 ℃ and kept for 2 hours, and the pour point depressant DJ1 is obtained, wherein the monomer conversion rate of the pour point depressant DJ1 is 99.3%, and the number average molecular weight is 41768. Further, the pour point depressant DJ1 contained a copolymer containing 64.3% by weight of a structural unit derived from the monomer represented by formula (1) and 35.7% by weight of a structural unit derived from the monomer represented by formula (2).

Example 3

Under the protection of nitrogen, 100kg of diluent oil is added into a reaction kettle provided with a mechanical stirrer, the mixture is heated to 83-91 ℃, 166kg of first monomer [ dodecyl methacrylate/tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate (C) is added at the feed inlet A at the speed of 48 kg/hour₁₂50% by weight, C₁₄18% by weight, C₁₆20% by weight, C₁₈12% by weight),

a mixture of 0.4kg of benzoyl peroxide and 0.5kg of dodecyl mercaptan was added dropwise to the reaction vessel and then slowly increased linearly so that when the total feed time was 2h, the flow rate was increased to 56 kg/h and then rapidly decreased linearlySmall so that when the total feed time was to 4 hours, the flow rate was reduced to 6 kg/hour. Simultaneously, 303kg of a second monomer [ decyl methacrylate/dodecyl methacrylate/tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate/eicosyl methacrylate (C) was added dropwise at an initial rate of 30 kg/hr at the feed inlet of B₁₀12% by weight, C₁₂27% by weight, C₁₄19% by weight, C₁₆18% by weight, C₁₈14% by weight, C₂₀Not more than 10% by weight),

a mixture of 0.75kg of benzoyl peroxide and 0.9kg of dodecyl mercaptan was added dropwise to the reactor, and the flow rate of the pump at feed port B was set to a linear increase so that when the total feed time was 2 hours, the flow rate was increased to 100 kg/hour, and then the flow rate was maintained for 2 hours. A. And when the feed inlets B are all dripped, continuously keeping the reaction kettle at 95 ℃ for 2 hours, then adding 0.2kg of benzoyl peroxide and 142kg of diluent oil, raising the temperature to 103 ℃ and keeping the temperature for 2 hours, and ending the reaction to obtain a pour point depressant J3, wherein the monomer conversion rate of the pour point depressant J3 is 98.9%, and the number average molecular weight is 43196. Further, the pour point depressant J3 contained a copolymer containing 35.4% by weight of a structural unit derived from the monomer represented by formula (1) and 64.6% by weight of a structural unit derived from the monomer represented by formula (2).

Example 4

100kg of diluent oil is added into a reaction kettle provided with a mechanical stirrer under the protection of nitrogen, the mixture is heated to 83-91 ℃, and 255kg of first monomer [ dodecyl methacrylate/tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate (C) is added at the feed inlet A at the speed of 40 kg/hour₁₂50% by weight, C₁₄18% by weight, C₁₆20% by weight, C₁₈12% by weight),

a mixture of 1.2kg of benzoyl peroxide and 1.0kg of dodecyl mercaptan was added dropwise to the reaction vessel, followed by a linear slow increase so that the flow rate increased to 50 kg/h when the total feed time was 3h, followed by a linear rapid decrease so that the flow rate decreased to 30 kg/h when the total feed time was 6 h. 150kg of a second monomer [ tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate/eicosyl methacrylate (C14: 38% by weight, C) were simultaneously added dropwise at an initial rate of 10 kg/h at the feed inlet B₁₆20% by weight, C₁₈25% by weight, C₂₀When the weight percentage is equal to 17 percent,

a mixture of 0.70kg of benzoyl peroxide and 0.60kg of dodecyl mercaptan was added dropwise to the reactor, and the flow rate of the pump at feed port B was set to a linear increase so that when the total feed time was 3 hours, the flow rate was increased to 30 kg/hour, and then the flow rate was maintained for feeding for 3 hours. A. And when the dropwise adding of the feed inlets B is finished, continuously keeping the reaction kettle at 95 ℃ for 2 hours, then adding 0.2kg of benzoyl peroxide and 66kg of diluent oil, heating to 103 ℃ and keeping for 2 hours to finish the reaction to obtain a pour point depressant J4, wherein the monomer conversion rate of the pour point depressant J4 is 99.7%, and the number average molecular weight is 42637. Further, the pour point depressant J4 contained a copolymer containing 63.0% by weight of a structural unit derived from the monomer represented by formula (1) and 27.0% by weight of a structural unit derived from the monomer represented by formula (2).

Test example

The test examples were used to test pour point depressant performance in base oils. The properties of the base oil are shown in table 1:

TABLE 1

Base oil	A	B	C	D	E	F
							Rank of	API-Ⅱ6	API-Ⅲ6	150SN	500SN	API-Ⅱ4	150BS
Viscosity at 100 ℃/(mm)²·s^-1)	5.67	5.54	5.46	11.22	3.97	29.6
							Viscosity index	112	121	90	95	114	98
Pour point/. degree.C	-18	-15	-15	-12	-15	-9

Pour point depressants J1-J4 and a reference pour point depressant DJ1 were added to the base oil, respectively, wherein the amounts of pour point depressants, the types of base oils, and the results obtained are shown in Table 2.

From the comparison of the results, it can be seen that the acrylate copolymer pour point depressant with a gradient molecular structure obtained by the method has excellent pour point depressing effect in various base oils, particularly, the pour point of the base oil is still obviously reduced when the addition amount is very small, and the pour point depressing efficiency is obviously improved.

TABLE 2

Note: in Table 2, pour point depressants are added based on the total weight of the base oil.

Examples 5-9 and comparative examples 2-5 of lubricating oil compositions for diesel engines

The formulation compositions of examples 5-9 and comparative examples 2-5 of the diesel engine lubricating oil compositions are shown in Table 3. The components are added into a mixing container according to the proportion, heated to 45-80 ℃ under normal pressure, stirred for 1-2 hours, and the CJ-4 diesel engine lubricating oil composition with the viscosity grade of 15W-40 is prepared.

These lubricating oil compositions and CJ-415W-40 market oil were subjected to a carbon black addition aging test to obtain simulated aged soot-containing oil. Carbon black was dispersed in a new oil of a lubricating oil composition by high-speed mechanical stirring using carbon black as a simulant of soot to form a dispersion of carbon black and oil, the carbon black content being 3%, and then an aging test was conducted. The aging test conditions were: 15ppm of iron naphthenate is added into 100g of dispersion liquid of carbon black and oil as a catalyst, the test temperature is 165 ℃, the oxygen flow is 150mL/min, and the aging time is 40 h. The carbon black-containing oil after aging was tested for MRV low temperature pumpability using ASTM D6896, and the lubricating oil composition new oil was tested for MRV low temperature pumpability, including yield stress and low temperature pumpability, using ASTM D4684. In the specification of API CJ-4 diesel engine oil, the Mack T-11A engine test of test oil 180h of the MRV low-temperature pumpability test temperature of soot-containing oil is-20 ℃, the pass standard is that the yield stress is less than 35Pa, and the low-temperature pumpability is not more than 25000mPa & s. The MRV low temperature pumpability test of the carbon-containing black oil after aging of the lubricating oil composition of the present invention was conducted at-20 deg.C and the test results are shown in Table 4.

From the results in Table 4, it can be seen that the MRV low temperature pumpability of the virgin oil was acceptable for the lubricating oil compositions formulated with the example pour point depressant J1-J4 and the comparative pour point depressant DJ1 with suitable viscosity modifiers, base oils and other functional additives, and that the yield stress and the MRV low temperature pumpability of the virgin oil and the aged carbon-containing black oil were unacceptable for the comparative example 5 without the addition of the pour point depressant. The carbon black oil MRV low temperature pumpability after aging of the lubricating oil composition using the pour point depressant of the examples is qualified in yield stress compared with the CJ-415W-40 market oil, and the MRV low temperature pumpability is smaller than that of the CJ-4 market oil, while the carbon black oil MRV low temperature pumpability after aging of the lubricating oil composition using the pour point depressant of the examples is larger than that of the CJ-4 market oil, and the yield stress disqualification phenomenon also occurs. The acrylate-based copolymer pour point depressant provided by the invention has an obvious improvement effect on the low-temperature pumping performance of aged soot-containing oil.

TABLE 4

Examples 10-12 and comparative examples 6-8 of lubricating oil compositions for diesel engines.

The formulation compositions of examples 10-12 and comparative examples 6-8 of the diesel engine lubricating oil compositions are shown in Table 5. The components are added into a mixing container according to the proportion, heated to 45-80 ℃ under normal pressure, stirred for 1-2 hours, and the CJ-4 diesel engine lubricating oil composition with the viscosity grade of 15W-40 is prepared. These lubricating oil compositions were subjected to a carbon black addition aging test in the same manner as described above, and MRV low temperature pumpability measurements were made of the carbon black-containing oil and virgin oil after aging, the test results being shown in Table 6.

As can be seen from the results in Table 6, the effect of the pour point depressant on the low temperature pumping performance of the aged lubricating oil is affected by additives such as an adhesive, an antioxidant, etc. The acrylate copolymer pour point depressant is reasonably compounded with proper functional additives such as viscosity index improver, base oil, antioxidant corrosion inhibitor, detergent dispersant and the like, so that the lubricating oil composition has excellent low-temperature performance, and particularly, the aged soot-containing lubricating oil has excellent low-temperature pumping performance. Can meet the requirements of CJ-4 grade high-grade diesel engine lubricating oil.

TABLE 6

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A diesel engine lubricating oil composition comprising the following components:

Less than R in the second monomer₂Average value of (2)

And is

R₃And R₄Each independently hydrogen or methyl;

the acrylate copolymer is prepared according to the method comprising the following steps:

b is greater than viscosity index improver;

c > dispersing agent;

d > a mixture of an alkylsalicylate and a sulfurized alkylphenate;

e > zinc dialkyldithiophosphate;

f > dialkyldithiocarbamate;

g is more than auxiliary antioxidant;

h is more than the balance of lubricating oil base oil.

2. The composition of claim 1, wherein Σ R₁＝12.2-13.5，∑R₂＝14.0-15.6。

3. The composition according to claim 1, wherein the acrylate-based copolymer contains 10 to 90 wt% of the structural unit derived from the first monomer and 10 to 90 wt% of the structural unit derived from the second monomer.

4. The composition of claim 1, wherein the olefin polymerization reaction has an initiation temperature of 50 to 180 ℃; the total dropping times t1 and t2 are both 1 to 12 hours.

5. The composition of claim 1, wherein the method for preparing the acrylate copolymer further comprises reacting the first mixture and the second mixture for 0.5-2 hours after the dropwise addition of the first mixture and the second mixture is completed, adding an initiator and a diluent oil, and then increasing the temperature to 100-150 ℃ to continue the reaction for 0.5-5 hours.

6. The composition of claim 1, wherein component a comprises from 0.01% to 2% by weight of the total weight of the lubricating oil composition.

7. The composition according to claim 1, wherein component B is selected from the group consisting of amorphous ethylene propylene copolymers, polymethacrylates, polyalkylmethacrylates, methacrylate copolymers, copolymers of styrene and acrylates, partially hydrogenated copolymers of styrene/isoprene, styrene/butadiene, isoprene/butadiene, and partially hydrogenated homopolymers of butadiene and isoprene, isoprene/divinylbenzene; the component B accounts for 0.1 to 25 percent of the total mass of the lubricating oil composition.

8. The composition according to claim 1, wherein component C is selected from polyisobutylene succinimide ashless dispersants and/or antioxidant polyisobutylene succinimide ashless dispersants; the component C accounts for 0.5-15% of the total mass of the lubricating oil composition.

9. The composition of claim 1 wherein component D is a mixture of calcium alkyl salicylate and calcium alkyl phenate sulfide; the component D accounts for 0.5 to 8 percent of the total mass of the lubricating oil composition.

10. The composition of claim 1 wherein the alkyl group of the zinc dialkyldithiophosphate is an alkyl group containing 2 to 12 carbon atoms; the addition amount of the component E in the lubricating oil composition is not more than 0.12% in terms of the mass fraction of phosphorus element.

11. The composition of claim 1, wherein the alkyl group of the dialkyldithiocarbamate is an alkyl group containing 2 to 12 carbon atoms; the component F accounts for 0.02-5% of the total mass of the lubricating oil composition.

12. The composition of claim 1 wherein component G is one or more of a phenolic antioxidant, an amine antioxidant, a phenolic ester antioxidant, and a thiophenolic ester antioxidant; the component F accounts for 0.1-6% of the total mass of the lubricating oil composition.

13. A process for preparing a composition as claimed in any one of claims 1 to 12, wherein the respective lubricant additives are added to the lubricant base oil and mixed by heating.