CN109679741B

CN109679741B - Gasoline engine lubricating oil composition and preparation method thereof

Info

Publication number: CN109679741B
Application number: CN201710971019.4A
Authority: CN
Inventors: 徐杰; 张耀; 段庆华; 武志强; 张倩; 刘依农; 夏青虹; 张峰
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: 2017-10-18
Filing date: 2017-10-18
Publication date: 2022-01-04
Anticipated expiration: 2037-10-18
Also published as: CN109679741A

Abstract

The invention provides a gasoline engine lubricating oil composition and a preparation method thereof. The gasoline engine lubricating oil composition comprises a gradient copolymer, a viscosity index improver, a dispersant, a detergent, zinc dialkyl dithiophosphate, dialkyl dithiocarbamate and/or dialkyl dithiocarbamate, an antioxidant, a friction improver and lubricating oil base oil. The composition has the phosphorus content of not more than 0.08 percent by mass, has very excellent low-temperature performance and oxidation resistance, and can meet the requirements of SM/GF-4 and SN/GF-5 high-grade gasoline engine lubricating oil.

Description

Gasoline engine lubricating oil composition and preparation method thereof

Technical Field

The invention relates to a lubricating oil composition, in particular to a gasoline engine lubricating oil composition.

Background

Low temperature performance is an important property of modern engine oils, and low temperature pumpability has been introduced into the specifications of engine oils over the last 30 years, but initially only for new oils. The low temperature pumping performance reflects the rheological behavior of the engine oil in the oil pump region. The failure of the low-temperature pumpability of the engine oil is caused by two mechanisms, namely, air resistance appears in a gel structure formed by wax crystallization at low temperature, so that an oil way is not smooth; the second is flow restriction caused by too high a viscosity. In the low temperature pumpability test (MRV), the flow restriction behavior was predicted by measuring the "low temperature pumpability" using the "yield stress" to simulate vapor lock. "

In recent years, due to the continuous progress of engines, the anti-oxidation load of oil products is increased, so that some lubricating oil passes the requirement of new oil pumpability, unqualified low-temperature pumping performance occurs at the later stage of the actual service life, and accidents such as vehicle burning and the like occur in vehicles. Therefore, III GA engine tests for specially measuring the low-temperature pumpability of used oil products are specified in specifications of GF-4/SM of gasoline engine oil which is sold in 2004 and specifications of GF-5/SN gasoline engine oil which is pushed out in 2010, namely III G oxidation tests are carried out to specially measure the low-temperature pumpability of waste oil, and the analysis result of MRV TP-1 with low-temperature pumpability is definitely required to meet the corresponding requirements of the current viscosity grade or the adjacent high-viscosity grade (5 ℃ higher). Because the program III G test has very high cost, a laboratory simulated oxidation aging method, namely a ROBO method, is introduced into the SN/GF-5 grade, and the ROBO method can replace the program III GA engine bench test and is used for simulating the aging of oil products in the program III GA test process.

Pour point depressants are used to improve the low temperature properties of oils in oil formulation development. Many types of pour point depressants have been developed in the prior art. CN 106520261A discloses a lubricant pour point depressant composition, which consists of a poly-alpha-olefin pour point depressant and a fumarate pour point depressant, wherein the mass ratio of the poly-alpha-olefin pour point depressant to the fumarate pour point depressant is 3: 1-5. WO 2015/110340 discloses a blend of two alkyl (meth) acrylate copolymers which improves the low temperature pumpability of the aged engine oil.

With the development of lubricating oils, higher demands are also made on the performance of pour point depressants. In view of this, there is still a need in the art for new pour point depressants with improved performance.

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 properties of the oil in all aspects are balanced through compounding of the additives, so that the increasingly strict low-temperature performance requirements of the oil are met.

Disclosure of Invention

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

In particular, the present invention relates to at least the following aspects:

1. a gasoline engine lubricating oil composition comprising a gradient copolymer, a viscosity index improver, a dispersant, a detergent, zinc dialkyldithiophosphate, dialkyldithiocarbamate and/or dialkyldithiocarbamate, an antioxidant, a friction modifier and a lubricating oil base oil, the method for producing the gradient copolymer comprising: a step of adding at least two monomers to a polymerization reaction system, and subjecting the at least two monomers to addition copolymerization reaction (particularly radical addition copolymerization reaction), wherein the at least two monomers each independently represent a compound represented by formula (I) and/or a mixture thereof,

in the formula (I), the compound represented by the formula (I),

radical R₁Represents H or

Preferably represents a compound of formula (I) or (II),

radical R₂Represents H or C_1-4Straight-chain or branched alkyl, preferably represents H or methyl,

the symbol a represents 0 or 1, preferably 1,

the radical R' represents H or the radical R₃Preferably represents a group R₃，

Radical R₃Represents C₁-C₃₀Straight-chain or branched alkyl, preferably representing C₆-C₂₄Straight or branched alkyl, more preferably C₆-C₂₀A straight chain alkyl group,

setting the initial time of adding the at least two monomers into the polymerization reaction system as t₀The termination time is t_mThen the monomer addition time of the at least two monomers is t (t ═ t)_m-t₀) When the monomer addition time is divided into m equal parts, the symbol m represents a closed interval [5, ∞ ]]An integer of (a), preferablyRepresents a closed interval [8, ∞]Preferably, the upper limit of the integer denoted by the symbol m is 20000, 10000, 5000, 1000, 500, 200, 100 or 50, at any monomer addition time t_xThe relative proportions of the at least two monomers added to the polymerization system being such that the average number of carbon atoms in the side chain X is the average number of carbon atoms in the NMR of a mixture of the at least two monomers in the relative proportions_xSatisfying the following relationship, the symbol x represents any integer from 0 to m,

X₀<X₁<…<X_m-1<X_m (V)

preferably from X₀To X_mGradually increasing, more preferably from X₀To X_mThe linearity increases.

2. The production method according to any one of the preceding aspects, wherein the termination time t of the monomer addition is set_mThe sum of the cumulative addition amounts of the at least two monomers to the polymerization reaction system within the monomer addition time is G, and is set at any monomer addition time t_xThe sum of the addition amounts of the at least two monomers to the polymerization reaction system is G_xThe symbol x represents an arbitrary integer from 0 to m, and the following relational expression holds,

G₀/G<G₁/G<…<G_j/G>…>G_m-1/G>G_m/G (VI)

in formula (VI), the symbol j represents a closed interval [ m/4, 3m/4 ]]An integer within, preferably representing a closed interval [ m/3, 2m/3]An integer within, more preferably representing a closed interval [2m/5, 3m/5]An integer of (a), and G₀+G₁+…+G_j+…+G_m-1+G_m＝G，

Preferably from G₀G to G_jG is gradually increased, more preferably from G₀G to G_jLinear increase of/G, or from G_jG to G_mG is gradually decreased, more preferably from G_jG to G_mthe/G is reduced in a linear manner,

more preferably G_xG and X_xThe following relational expression is satisfied,

in formula (VII), the symbol μ represents any value within the open interval (12.5, 14.2), preferably any value within the open interval (12.6, 13.8), and the symbol σ represents any value within the open interval (0.5, 2).

3. The process according to any one of the preceding aspects, wherein the group R₃Represents C₁₀-C₁₈The proportion (on a molar basis) of the compounds of formula (I) described above, which are linear or branched alkyl groups, relative to the total monomer amount, is from 40% to 95%, preferably from 55% to 95%.

4. The production method according to any one of the preceding aspects, wherein X is₀Represents a closed interval [6.5, 12.5 ]]Any value within, preferably representing a closed interval [7.8, 12.0 ]]Or said X is any one of the values in_mRepresents a closed interval [13.8, 19.5 ]]Any value within, preferably representing a closed interval [14.5, 18.2 ]]Any one of the values in (b).

5. The production method according to any one of the preceding aspects, wherein the ratio G_jG is from 20 to 75%, preferably from 25 to 65%, or the ratio G₀G or the ratio G_mthe/G is from 0.01 to 20%, preferably from 0.1 to 10%.

6. The production process of any one of the preceding aspects, wherein the reaction temperature of the copolymerization reaction is from 50 ℃ to 180 ℃, preferably from 55 ℃ to 165 ℃, more preferably from 60 ℃ to 150 ℃, the reaction time of the copolymerization reaction is from 1 hour to 24 hours, preferably from 1.5 hours to 20 hours, and the monomer addition time t is from 0.5 hours to 12 hours, preferably from 1 hour to 10 hours.

7. The lubricating oil composition of any preceding aspect, wherein the gradient copolymer comprises from 0.01% to 2% (preferably from 0.05% to 1.5%) by weight of the total lubricating oil composition; the viscosity index improver accounts for 0.1-25% (preferably 0.5-20%) of the total mass of the lubricating oil composition; the dispersant accounts for 0.5 to 15 percent (preferably 1 to 12 percent) of the total mass of the lubricating oil composition; the detergent accounts for 0.1-10% (preferably 0.2-6%) of the total mass of the lubricating oil composition; the addition amount of the zinc dialkyl dithiophosphate in the lubricating oil composition is not more than 0.08% (preferably 0.06% -0.08%) in terms of the mass fraction of phosphorus element; the dialkyl dithiocarbamate and/or the dialkyl dithiocarbamate accounts for 0.05 to 1.5 percent (preferably 0.1 to 1.2 percent) of the total mass of the lubricating oil composition; the antioxidant accounts for 0.1-6% (preferably 0.2-3%) of the total mass of the lubricating oil composition; the friction modifier accounts for 0.01-5% (preferably 0.02-2%) of the total mass of the lubricating oil composition; the lubricant base oil constitutes the main component of the lubricating oil composition.

8. The lubricating oil composition of any preceding aspect, wherein the viscosity index improver is selected from the group consisting of amorphous ethylene propylene copolymers, polymethacrylates, polyalkylmethacrylates, methacrylate copolymers, copolymers of styrene and acrylates, hydrogenated or partially hydrogenated copolymers of styrene/isoprene, styrene/butadiene, isoprene/butadiene, partially hydrogenated homopolymers of butadiene and isoprene, isoprene/divinylbenzene; the dispersant is selected from one or more of mono-polyisobutylene succinimide, di-polyisobutylene succinimide, high molecular polyisobutylene succinimide, boronized polyisobutylene succinimide and polyisobutylene succinate; the detergent is selected from one or more of a sulphonate, an alkyl salicylate and a sulphurised alkyl phenate; the alkyl in the zinc dialkyl dithiophosphate is C2-C12 alkyl; the alkyl in the dialkyl dithiocarbamate and/or the dialkyl dithiocarbamate is C2-C12 alkyl; the antioxidant is selected from one or more of phenol type antioxidant, amine type antioxidant, phenolic ester type antioxidant and sulfophenolic ester type antioxidant; the friction modifier is selected from an ashless friction modifier and/or an oil-soluble organo-molybdenum friction modifier; the lubricating oil base oil is selected from one or more of API I base oil, II base oil, III base oil, IV base oil and V base oil.

The amorphous ethylene propylene copolymer is a non-crystalline or semi-crystalline ethylene propylene copolymer having an ethylene content of 25 Wt% to 60 Wt% and a crystallinity of 0% to 2.5%, preferably 0% to 2%, more preferably 0% to 1.5%. The viscosity index improver is commercially available under the trade designations LZ7070, LZ7065, LZ7067, LZ7077 from Lubrizol, SV260, SV261 and the like from infinium.

The dispersant is selected from one or more of mono-polyisobutylene succinimide, di-polyisobutylene succinimide, high molecular polyisobutylene succinimide, boronized polyisobutylene succinimide and polyisobutylene succinate, wherein the number average molecular weight of a Polyisobutylene (PIB) part is 500-4000, preferably 700-3000 and most preferably 1000-2400, the mass fraction of boron element in the boronized polyisobutylene succinimide is 0.1-3%, preferably 0.2-2.5%, and the polyisobutylene succinate can be selected from one or more of polyisobutylene pentaerythritol succinate, polyisobutylene glycerol succinate and polyisobutylene ethylene glycol succinate. The dispersant may be selected from T151 and T152 produced by south additive Co., Ltd, T161 produced by Suzhou special oil product factory, T155, T161A and T161B produced by additive factory Co., Ltd, LZL 57 produced by Luborun additive Co., Ltd, LZ6418 and LZ6420 produced by Luborun Co., Ltd, Hitec646 produced by Yakuton Co., Ltd, MX3316 produced by Agip Petroli Co., Ltd, Hitec648 and Hitec7714 produced by Yakuton Co., Ltd, and LZ935 and LZ936 produced by Luborun Co., Ltd.

The detergent is preferably one or more of a sulphonate, an alkyl salicylate and a sulphurised alkyl phenate. The detergent may be selected from, but not limited to, T106B and T122 produced by Ryofeng chemical company, Inc., LZL109B, LZL112, LZL115A and LZL115B produced by Lubrizol additives, LZ6499, LZ6500, LZ6477C and LZ6478 produced by Afton, OLOA219 produced by Chevron Oronite, C9375, C9012, C9391, C9330 and C9394 produced by Infineum, OSCA420 produced by OSCA, SAP007 produced by Shell.

The alkyl group in the zinc dialkyldithiophosphate is preferably a C2-C8 alkyl group, 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 T202 and T203 produced by Wuxi south petroleum additive Co., Ltd, T202 and T203 produced by additive plant of Kanzhou petrochemical company, primary-secondary alkyl T204 and secondary alkyl T205, LZ1371 and LZ1375 produced by Lubrizol corporation, C9417, C9425 and C9426 produced by Infineum corporation, Hitec7169 and Hitec1656 produced by Afton company, and the like.

The alkyl group in the dialkyl dithiocarbamate and/or the dialkyl dithiocarbamate is a C2-C12 alkyl group, preferably a C4-C8 alkyl group. The dialkyldithiocarbamate is selected from one or more of the metal salts of zinc, calcium, sodium, barium and magnesium of dialkyldithiocarbamic acid, preferably zinc dialkyldithiocarbamate. The dialkyl dithiocarbamate and/or the dialkyl dithiocarbamate may be commercially available under a brand name selected from, but not limited to, Vanlube AZ, Vanlube 7723, available from R.T. Vanderbilt, U.S.A., BZ available from Wuhan Yuan river chemical plant, and the like.

The phenolic antioxidant can be one or more of 2, 6-di-tert-butyl-alpha-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 one or more of alkylated aniline, alkylated diphenylamine and phenyl alpha-naphthylamine, preferably an oil-soluble dialkyl diphenylamine, for example one or more of dibutyl diphenylamine, dioctyl diphenylamine, dinonyl diphenylamine, butyl octyl diphenylamine and phenyl naphthylamine. Commercially available alkylated diphenylamines such as IRGANOX L-01, IRGANOX L-57 from BASF corporation, Germany, T534 from BASF corporation, Lanzhou Luobu Brand additives, LZ5150A from Lanzhou Luobun additive Co., Ltd., VANLUBE NA, VANLUBE961, dioctyldiphenylamine VANLUBE 81 from R.T. Vanderbilt corporation, P from Rhein Chemie corporation, Germany, P' diisooctyldiphenylamine RC7001, N438L from Chemtura corporation, and the like. The phenolic ester antioxidant is preferably a hydroxyphenyl carboxylic acid ester with molecular weight of 200-500, such as IRGANOX XL-135 from BASF of Germany and T512 from Fine chemical engineering developers of 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.

The ashless friction modifier is selected from one or more of fatty acid polyol esters, aliphatic amines and aliphatic amides, wherein the aliphatic hydrocarbon group is a saturated or unsaturated hydrocarbon group having 6 to 60 carbon atoms, preferably 10 to 50 carbon atoms. The fatty acid polyol ester comprises fatty acid glyceride, fatty acid pentaerythritol ester, fatty acid glycol ester, fatty acid succinate, fatty acid ethanolamine ester, fatty acid diethanolamine ester, fatty acid triethanolamine ester, and monoester, diester or polyester of the compounds, such as oleic acid monoglyceride, oleic acid diglyceride, stearic acid monopentaerythritol ester, lauric acid glycol diester, oleic acid diethanolamine monoester, oleic acid triethanolamine monoester, etc.; the aliphatic amines include hydrocarbyl-substituted mono-or polyamines, alkoxylated hydrocarbyl-substituted mono-or polyamines, and alkyl ether amines, etc., such as ethoxylated tallow amine and ethoxylated tallow ether amine; examples of aliphatic amides include oleic acid amide, cocoamide, and the like.

The oil-soluble organic molybdenum friction modifier is selected from one or more of molybdenum dialkyl dithiophosphate, oxygen molybdenum dialkyl dithiophosphate, molybdenum dialkyl dithiocarbamate, molybdenum xanthate, molybdenum thioxanthate, trinuclear molybdenum-sulfur complex, molybdenum amine complex, molybdate ester and other oil-soluble organic molybdenum friction modifiers, and is preferably organic molybdate ester. The above-described organomolybdenum compounds have an organo group therein that includes a sufficient number of carbon atoms, typically between 6 and 60, preferably between 10 and 50, to render the organomolybdenum compound soluble or dispersible in the base oil. The oil-soluble organic molybdenum friction modifier may be selected from Molyvan L, 822, 855, manufactured by Vanderbilt, usa, 515, 525, 710, manufactured by asahi electric company, japan, and the like.

The lubricant base oil is preferably an API group II base oil and/or an API group III base oil.

The method of preparing a gasoline engine lubricating oil composition of the present invention comprises the step of mixing various additives as described in any of the preceding aspects with a lubricating base oil.

The gasoline engine lubricating oil composition has excellent low-temperature performance and oxidation resistance, and the composition has the phosphorus content of not more than 0.08 percent calculated by mass fraction and can meet the requirements of high-grade gasoline engine lubricating oil of SM/GF-4 and SN/GF-5 grades.

Detailed Description

The following detailed description of the embodiments of the present invention is provided, but it should be noted that the scope of the present invention is not limited by the embodiments, but is defined by the appended claims.

In the context of the present invention, the term "(meth) acrylic acid" refers to either acrylic acid or methacrylic acid.

Unless otherwise expressly indicated, all percentages, parts, ratios, etc. mentioned in this specification are by weight unless otherwise not in accordance with the conventional knowledge of those skilled in the art.

According to one aspect of the invention, the gradient copolymer has a side chain average carbon number X of generally from 5 to 20, preferably from 11.5 to 17, preferably from 11.5 to 16.2, more preferably from 12.2 to 15.7, more preferably from 12.2 to 15.5.

According to one aspect of the invention, the side chain average carbon number X of the n polymer components is generally from 5 to 20, preferably from 11.5 to 17, preferably from 11.5 to 16.2, more preferably from 12.2 to 15.7, more preferably from 12.2 to 15.5.

According to one aspect of the invention, the symbol n represents an integer within the closed interval [5, ∞ ], preferably an integer within the closed interval [8, ∞ ]. Here, the symbol n represents an integer, and the lower limit thereof may be 5 or 8, or may be 10 or 20. The upper limit of the integer represented by the symbol n may be ∞, or 20000, 10000, 5000, 1000, 500, 200, 100, or 50.

According to one aspect of the invention, the gradient copolymer may be produced by one or more of the following production methods. In the following of the present description, for the sake of simplicity, any matter not described in detail or specifically with respect to the manufacturing process, such as the type of reactor, the way of using various additives, the pretreatment of the feed, the separation of the reaction products, etc., may be directly referred to the corresponding matter known in the art.

According to one aspect of the present invention, the production method comprises a step of adding at least two monomers to a polymerization reaction system to cause addition copolymerization of the at least two monomers.

According to one aspect of the present invention, in order to facilitate the implementation of the addition copolymerization reaction, the at least two monomers are sometimes added to the polymerization reaction system in the form of a feed mixture. Here, as the feed mixture, in addition to the at least two monomers, one or more additives conventionally used for addition copolymerization such as a solvent, a diluent, an initiator, a molecular weight modifier, a polymerization catalyst and the like may be further generally contained as necessary. Furthermore, the type and amount of these additives can be determined by the requirements of the prior art, and the present invention is not particularly limited thereto.

According to one aspect of the present invention, in the polymerization reaction system, the at least two monomers undergo an addition copolymerization reaction, particularly a free radical addition copolymerization reaction, of carbon-carbon double bonds, to obtain a gradient copolymer. The gradient copolymer includes the gradient copolymer of the present invention described in various aspects of the present specification.

According to one aspect of the present invention, the reaction temperature of the addition copolymerization reaction is generally from 50 ℃ to 180 ℃, preferably from 55 ℃ to 165 ℃, more preferably from 60 ℃ to 150 ℃.

According to an aspect of the present invention, the reaction time of the addition copolymerization reaction is generally from 1 hour to 24 hours, preferably from 1.5 hours to 20 hours.

According to an aspect of the present invention, the addition copolymerization reaction may be carried out in any manner of bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, etc., preferably solution polymerization.

According to an aspect of the present invention, in order to facilitate the improvement of the monomer conversion, it is also possible to continue the addition copolymerization reaction for 0.5 to 2 hours after the end of the monomer addition, or to raise the temperature of the polymerization reaction system to 100 ℃ and 150 ℃ and continue the reaction for 0.5 to 5 hours after further addition of an initiator, a polymerization catalyst, a diluent, or the like, as necessary. These reaction modes are known to those skilled in the art.

According to an aspect of the present invention, as the initiator, those conventionally used in the art, particularly, radical polymerization initiators can be used, and there is no particular limitation. Specific examples of the initiator include azo initiators, peroxide initiators, and redox initiators. These initiators may be used singly or in combination in any ratio. In addition, the amount of the initiator used in the present invention is not particularly limited, and those conventionally known in the art can be applied, for example, as the total amount of the initiator used in the whole addition copolymerization reaction, generally 0.01 to 2.5 parts by weight, preferably 0.05 to 2 parts by weight, more preferably 0.1 to 1.5 parts by weight, relative to 100 parts by weight of the total amount of the monomers.

According to an aspect of the present invention, as the diluent, those conventionally used in the art, particularly diluent oil, may be used, without particular limitation.

According to an aspect of the present invention, as the molecular weight regulator, those conventionally used in the art can be used, and there is no particular limitation. Specific examples of the molecular weight modifier include dodecyl mercaptan and 2-mercaptoethanol. These molecular weight regulators may be used singly or in combination of two or more in any ratio. In addition, the amount of the molecular weight regulator used in the present invention is not particularly limited, and those conventionally known in the art can be applied.

According to an aspect of the present invention, as the polymerization catalyst, those conventionally used in the art can be used, and there is no particular limitation. Specific examples of the polymerization catalyst include radical polymerization catalysts, particularly ziegler-natta catalysts. These polymerization catalysts may be used singly or in combination in any ratio. In addition, the amount of the polymerization catalyst used in the present invention is not particularly limited, and those conventionally known in the art can be applied.

According to one aspect of the present invention, the addition copolymerization reaction is generally carried out in an inert atmosphere. Here, the inert gas atmosphere refers to an inert gas atmosphere that does not chemically react with the reactant and the product. Examples of the inert gas include nitrogen gas and an inert gas. The inert gas atmosphere may be maintained by, for example, continuously introducing the inert gas into the polymerization reaction system.

According to one aspect of the invention, the at least two monomers each independently represent a compound of formula (I). One or more of the at least two monomers may sometimes also be present as a monomer mixture. In this case, according to this aspect of the present invention, the two or more monomer compounds contained in the monomer mixture each independently represent a compound represented by formula (I).

According to one aspect of the invention, in formula (I), the radical R₁Represents H or

Preferably represents H. Here, the radical R' represents H or the radical R₃Preferably represents a group R₃。

According to one aspect of the invention, in formula (I), the radical R₂Represents H or C_1-4Straight-chain or branched alkyl, preferably represents H or methyl.

According to one aspect of the invention, in formula (I), the symbol a represents 0 or 1, preferably 1.

According to one aspect of the invention, in formula (I), the radical R₃Represents C₁-C₃₀Straight-chain or branched alkyl, preferably representing C₆-C₂₄Straight or branched alkyl, more preferably C₆-C₂₀Straight chain alkyl or C₈-C₂₄A linear alkyl group.

According to one aspect of the invention, it is preferred that the group R₃Represents C₁₀-C₁₈The proportion (on a molar basis) of the linear or branched alkyl group of the compound of formula (I) to the total monomer amount (the total amount of the at least two monomers) is generally from 40% to 95%, preferably from 55% to 95%.

According to one aspect of the present invention, as the compound represented by the formula (I), there may be mentioned, for example, fumaric acid monoc₁-C₃₀Straight or branched alkyl ester, fumaric acid di-C₁-C₃₀Straight or branched chain alkyl ester, C₃-C₃₀Linear or branched alpha-olefins and (meth) acrylic acid C₁-C₃₀Straight or branched alkyl esters, more specifically for example fumaric acid mono C₈-C₂₄Straight or branched alkyl ester, fumaric acid di-C₈-C₂₄Straight or branched chain alkyl ester, C₆-C₂₀Linear or branched alpha-olefins and (meth) acrylic acid C₆-C₂₀Straight or branched alkyl esters, more specifically for example fumaric acid mono C₈-C₂₄Linear alkyl ester, fumaric acid di-C₈-C₂₄Straight chain alkyl ester, C₆-C₂₀Linear alpha-olefins and (meth) acrylic acid C₆-C₂₀A linear alkyl ester. These monomers may be used singly or in combination in any ratio.

According to an aspect of the present invention, as the fumaric acid mono C₈-C₂₄Straight or branched alkyl ester, and specific examples thereof include fumaric acid mono C₈Linear alkyl ester, fumaric acid mono C₁₀Linear alkyl ester, fumaric acid mono C₁₂Linear alkyl ester, fumaric acid mono C₁₄Linear alkyl ester, fumaric acid mono C₁₆Linear alkyl ester, fumaric acid mono C₁₈Linear alkyl ester, fumaric acid mono C₂₀Linear alkyl ester, fumaric acid mono C₂₂Linear alkyl esters and fumaric acid mono C₂₄A linear alkyl ester. These fumaric acid monomers₈-C₂₄The linear or branched alkyl esters may be used singly or in combination in any ratio.

According to an aspect of the present invention, as the fumaric acid di-C₈-C₂₄Straight or branched alkyl ester, and specific examples thereof include fumaric acid di-C₈Linear alkyl ester, fumaric acid di-C₁₀Linear alkyl ester, fumaric acid di-C₁₂Linear alkyl ester, fumaric acid di-C₁₄Linear alkyl ester, fumaric acid di-C₁₆Linear alkyl ester, fumaric acid di-C₁₈Linear alkyl ester, fumaric acid di-C₂₀Linear alkyl ester, fumaric acid di-C₂₂Linear alkyl esters and fumaric acid di-C₂₄A linear alkyl ester. These fumaric acid di-C₈-C₂₄The linear or branched alkyl esters may be used singly or in combination in any ratio.

According to an aspect of the present invention, as said C₆-C₂₀Specific examples of the linear or branched alpha-olefin include 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene. These C₆-C₂₀The linear or branched alpha-olefin may be used singly or in combination of two or more kinds in an arbitrary ratio.

According to an aspect of the present invention, as the (meth) acrylic acid C₆-C₂₀Examples of the linear or branched alkyl ester include C (meth) acrylate₆Straight-chain alkyl ester, (meth) acrylic acid C₈Straight-chain alkyl ester, (meth) acrylic acid C₁₀Straight-chain alkyl ester, (meth) acrylic acid C₁₂Straight-chain alkyl ester, (meth) acrylic acid C₁₄Straight-chain alkyl ester, (meth) acrylic acid C₁₆Straight-chain alkyl ester, (meth) acrylic acid C₁₈Straight-chain alkyl esters and (meth) acrylic acid C₂₀A linear alkyl ester. These (meth) acrylic acids C₆-C₂₀The linear or branched alkyl esters may be used singly or in combination in any ratio.

According to one aspect of the present invention, the compound represented by the formula (I) may be commercially available or may be manufactured by various methods known in the art. As a specific example, the (meth) acrylic acid C₆-C₂₀The linear or branched alkyl ester may be prepared by reacting (meth) acrylic acid with C₆-C₂₀Obtained by esterification of a linear or branched alkanol, optionally with methyl (meth) acrylate and C₆-C₂₀The ester interchange reaction of the linear or branched alkyl alcohol is not particularly limited.

According to one aspect of the present invention, the addition of the at least two monomers to the polymerization system is initiated at time t₀The termination time is t_mThen the monomer addition time of the at least two monomers is t (t ═ t)_m-t₀). In order to increase the monomer conversion as much as possible, or depending on the manner of monomer addition of the at least two monomers, the monomer addition time is generally shorter than the reaction time of the copolymerization reaction. For example, the monomer addition time is generally from 0.5 to 12 hours, preferably from 1 to 10 hours.

According to one aspect of the invention, when dividing the monomer addition time t into m equal parts, at any monomer addition time t_xLet the average carbon number of the side chains of the at least two monomers be X_xThe following relational expression holds. In other words, at any monomer addition time t_xThe relative proportions of the at least two monomers added to the polymerization system being such that the average number of carbon atoms in the NMR side chain of a (hypothetical) mixture of the at least two monomers, X, is_xThe following relational expression is satisfied. Here, the symbol x represents an arbitrary integer from 0 to m.

X₀<X₁<…<X_m-1<X_m (V)

According to one aspect of the inventionSide chain average carbon number X of at least two monomers_xAs previously stated in the present specification, refers to the average carbon number of the side chains of a (fictitious) mixture of said at least two monomers in a predetermined ratio, wherein said predetermined ratio refers to the time t at which any one of the monomers is added_xThe relative proportions of the at least two monomers added to the polymerization system.

According to one aspect of the invention, the at least two monomers are added at the monomer addition time t_xThe relative proportion to be added to the polymerization reaction system is not particularly limited, and may be any value as long as it enables the side chain average carbon number X of the hypothetical mixture_xThe formula (V) may be satisfied. For simplicity, it is assumed that the at least two monomers represent two monomers, monomer a and monomer B, wherein the average carbon number of the side chain of monomer a is greater than the average carbon number of the side chain of monomer B. In order to satisfy the regulation of the formula (V), the starting time t of the addition of the two monomers to the polymerization system₀To the end time t_mThe amount of the monomer B may be gradually increased while maintaining the amount of the monomer B, gradually decreased while maintaining the amount of the monomer a, or both may be changed so that the amount of the monomer B is relatively decreased as compared with the amount of the monomer a.

According to one aspect of the invention, the addition amounts of the monomer A and the monomer B can be manually regulated or automatically regulated by a program, so that the addition amount proportion of the monomer A and the monomer B is continuously changed, and the total addition amount is continuously changed. For example, the simple example: at the initial moment t of the polymerization₀To the end time t_mAnd manually and continuously regulating and controlling the addition rate of the monomer A in an intermittent manner by setting m control points so as to discontinuously realize the relative reduction of the addition amount of the monomer B compared with the addition amount of the monomer A. Or can be easily developed and mastered by the personnel in the industry by setting a control program, and the control of the addition rate of the monomer A is continuously realized by the control programThereby satisfying the regulation of the formula (V).

According to one aspect of the invention, the symbol m represents an integer within the closed interval [5, ∞ ], preferably an integer within the closed interval [8, ∞ ]. Here, the symbol m represents an integer, and the lower limit thereof may be 5 or 8, or may be 10 or 20. The upper limit of the integer represented by the symbol m may be ∞, or 20000, 10000, 5000, 1000, 500, 200, 100, or 50.

According to an aspect of the present invention, a larger value of the integer represented by the symbol m indicates a more continuous change in the addition timing of two adjacent monomers, and also means a more continuous change in the average carbon number of the side chain at the addition timing of two adjacent monomers. When the value of the integer represented by the symbol m is sufficiently large, for example, the upper limit value thereof reaches ∞, this does not mean that the upper limit value actually reaches ∞ in terms of value, but means that the average carbon number of the side chain has reached the extent of continuous or stepless smooth change with continuous change in the monomer addition timing. For example, when m ∞, the number of average carbon numbers of the side chains is from X₀To X_mIt no longer appears as a finite incremental progression of changes, but as a continuous incremental change, in particular as an infinite or smooth incremental change.

According to one aspect of the present invention, the number of the average carbon number X of the side chain is from X as shown in the formula (V)₀To X_mPresent as an incremental change, such as a gradual incremental change or a linear incremental change. The increment amplitude (also called step size) between any two adjacent X in the incremental change is not particularly limited by the invention, as long as the effective increment is considered by the person skilled in the art. The incremental change may be an equal-step incremental change or an unequal-step incremental change, and is not particularly limited. The step size may be, for example, any value in the range of 0.01 to 4.00 or any value in the range of 0.05 to 1.5, but the present invention is not limited thereto.

According to an aspect of the present invention, as said X₀It isRepresents the starting time t of the addition of the at least two monomers to the polymerization system₀The average carbon number of the side chain of (a) also represents the starting point and the minimum value of the whole incremental change, and may be, for example, any value within a range from 6.5 to 12.5 or any value within a range from 7.8 to 12.0, but the present invention is not limited thereto. In addition, as the X_mIt represents the termination time t of the addition of said at least two monomers to said polymerization system_mAlso represents the end point and the maximum value of the overall incremental change, such as any value in the range from 13.8 to 19.5, or any value in the range from 14.5 to 18.2, but the invention is not limited thereto.

According to one aspect of the invention, the termination time t of the monomer addition is set_mThe sum of the cumulative addition amounts of the at least two monomers to the polymerization reaction system within the monomer addition time t is G, and is set at any monomer addition time t_xThe sum of the addition amounts of the at least two monomers to the polymerization reaction system is G_xThe symbol x represents an arbitrary integer from 0 to m, and the following relational expression holds. The ratio G is sometimes described below_xThe term,/G is simply referred to as the addition amount ratio.

G₀/G<G₁/G<…<G_j/G>…>G_m-1/G>G_m/G (VI)

According to one aspect of the invention, in said formula (VI), the symbol j represents a closed interval [ m/4, 3m/4 ]]An integer within, preferably representing a closed interval [ m/3, 2m/3]An integer within, more preferably representing a closed interval [2m/5, 3m/5]An integer of (a), and G₀+G₁+…+G_j+…+G_m-1+G_m＝G。

According to one aspect of the invention, at any monomer addition time t_xAnd adding the at least two monomers to the polymerization reaction system, wherein the at least two monomers are represented by q monomers. Here, the symbol q represents the number of monomer species involved in the production method, and may be, for example, an arbitrary integer of from 2 to 100 or an integer of from 2 to 2Any integer of 0, in particular from 2 to 5. Here, let us say that each monomer is added at the monomer addition time t_xThe amount (absolute value) added alone to the polymerization reaction system was g_sAnd the symbol s represents any integer from 1 to q, the sum of these individual addition amounts is equal to said G_xThe ratio between these individual addition amounts is the time t at which the at least two monomers are added_xRelative proportions added to the polymerization system. At any monomer addition time t, as described earlier in this specification_xThe relative proportions are required so that the side chain average carbon number X of the hypothetical mixture_xSatisfies the specification of the formula (V). This is a requirement set forth for the relative amounts of these separate additions of the at least two monomers. According to this aspect of the present invention, there is no particular limitation on the absolute value of each of these individual addition amounts of the at least two monomers, as long as the sum thereof reaches the G_xAnd further causing said G_xOr the G_xIt is sufficient that/G satisfies the specification of the formula (VI). For simplicity, it is assumed that the at least two monomers represent two monomers, monomer a and monomer B, wherein the average carbon number of the side chain of monomer a is greater than the average carbon number of the side chain of monomer B. In order that the amounts of the two monomers added individually satisfy both the regulation of the formula (V) and the regulation of the formula (VI), the starting time t of the addition of the two monomers to the polymerization reaction system₀To the moment of monomer addition t_jGradually increasing the amount of the monomer A while maintaining the amount of the monomer B added, and then starting from the monomer addition time t_jTo the end of the monomer addition_mThe amount of the monomer B added was gradually decreased while the amount of the monomer A added was kept constant.

According to one aspect of the invention, the value of the addition ratio is from G, as shown in the formula (VI)₀G to G_jthe/G is presented as an incremental change, such as a gradual incremental change or a linear incremental change. The invention does not specifically limit the increment amplitude (also called step size) between any two adjacent numerical values in the incremental change, as long as the increment amplitude is not limited by the inventionTo the extent that one of skill in the art would recognize that effective incremental increases have been achieved. The incremental change may be an equal-step incremental change or an unequal-step incremental change, and is not particularly limited. The step size may be, for example, any value in the range of 0.05% to 20% or any value in the range of 0.1% to 5%, but the present invention is not limited thereto.

According to an aspect of the present invention, the addition amount ratio G is₀(iv)/G, which represents the starting time t at which the at least two monomers are added to the polymerization system₀The ratio of the (instantaneous) total addition amount of the at least two monomers with respect to the total addition amount G of the at least two monomers over the entire monomer addition time t also represents the starting point and the minimum value of the entire incremental change, and may be, for example, any value in the range from 0.01% to 20%, or any value in the range from 0.1% to 10%, but the present invention is not limited thereto. The addition amount ratio G is defined as_jG, which represents the time t at which the monomer is added_jThe ratio of the (instantaneous) total addition amount of the at least two monomers with respect to the total addition amount G also represents the end point and the maximum value of the entire incremental change, and may be, for example, any value in the range from 20% to 75%, or any value in the range from 25% to 65%, but the present invention is not limited thereto.

According to one aspect of the invention, the value of the addition ratio is from G, as shown in the formula (VI)_jG to G_mthe/G is presented as a decreasing change, such as a gradual decreasing change or a linear decreasing change. The present invention does not specifically limit the decrement amplitude (also referred to as step size) between any two adjacent values in the decrement change, as long as the person skilled in the art considers that the effective decrement has been achieved. The decrement change may be an equal-step decrement change or an unequal-step decrement change, and is not particularly limited. The step size may be, for example, generally any value in the range of 0.05% to 20%, or any value in the range of 0.1% to 5%, but the present invention is not limited theretoAnd is not limited thereto.

According to an aspect of the present invention, the addition amount ratio G is_jG, which represents the time t at which the monomer is added_jThe ratio of the (instantaneous) total addition amount of the at least two monomers with respect to the total addition amount G also represents the starting point and the maximum value of the overall decreasing change, and may be, for example, any value in the range from 20% to 75%, or any value in the range from 25% to 65%, but the present invention is not limited thereto. The addition amount ratio G is defined as_m(iv)/G, which represents the end time t at which the addition of the at least two monomers to the polymerization system is terminated_mThe ratio of the (instantaneous) total addition amount of the at least two monomers with respect to the total addition amount G also represents the end point and the minimum value of the overall decreasing variation, and may be, for example, any value in the range from 0.01% to 20%, or any value in the range from 0.1% to 10%, but the present invention is not limited thereto.

According to an aspect of the invention, the addition amount ratio G_mThe ratio G of the amount of addition to the amount of₀The groups represented by the formula are not particularly limited, and may be the same or different.

According to one aspect of the invention, the value of the addition ratio is from G, as shown in the formula (VI)₀G to G_mthe/G shows a distribution state with two sides low and the middle high, and is very similar to a Gaussian distribution. Therefore, according to one embodiment of the present invention, in a desirable state, the numerical value of the addition amount ratio is taken as the ordinate, the numerical value of the average carbon number X of the side chain is taken as the abscissa, and the starting time t at which the addition from the at least two monomers to the polymerization reaction system is started is taken as₀To the termination time t of the addition of said at least two monomers to said polymerization system_mThe relationship is, or substantially corresponds to, a gaussian distribution, such as shown in formula (VII). By "substantially in line" is meant that the relationship between the two deviates slightly from the gaussian distribution shown in said formula (VII), but within a range acceptable to a person skilled in the art.

According to one aspect of the invention, in said formula (VII), the symbol x represents any integer from 0 to m, the symbol μ represents any value within the open interval (12.5, 14.2), preferably any value within the open interval (12.6, 13.8), and the symbol σ represents any value within the open interval (0.5, 2). Pi is the circumferential ratio, which can be generally taken as 3.141592654 or 3.14, and e is a natural constant, which can be generally taken as 2.718281828 or 2.72.

Examples

The present invention will be described in further detail with reference to examples, but the present invention is not limited to these examples.

In the following examples and comparative examples, the respective contents of the copolymer and the diluent oil and the respective monomer contents in the copolymer were calculated in terms of the charged amounts.

In the context of the present invention, including in the following examples and comparative examples, the respective measuring methods and calculation methods were carried out as follows.

1. Gel Permeation Chromatography (GPC) resolution method

Operating the instrument: model 1515 gel permeation chromatograph manufactured by Waters corporation, usa. The detector was a Waters 2414 refractive index detector. The solvent used for preparing the standard was chromatographically pure tetrahydrofuran manufactured by Acros corporation. The chromatographic column is provided by Waters company and is formed by connecting 3 silica gel columns with different pore diameters in series, and the specific specifications are as follows:

(1)Waters

HR 0.5THF, a relative molecular weight measurement ranging from 1 to 1000 (7.8X 300mm),

(2)Waters

HR 1THF, a relative molecular weight measurement range of 100-,

(3)Waters

HR 3THF, relative molecular weight measurement range 5000-.

The operating conditions are as follows: the mobile phase is tetrahydrofuran, the flow rate of the mobile phase is 1.0mL/min, the column temperature is 35 ℃, the detector temperature is 35 ℃, and the sample injection amount is 200 mu L.

Splitting: 0.02 to 0.2g of the sample was dissolved in 10mL of tetrahydrofuran and shaken up to obtain a homogeneous solution. The solution was then subjected to GPC analysis on the operating instrument under the operating conditions. From the appearance of a chromatographic peak on a gel chromatographic spectrum until the end of the chromatographic peak, a volumetric flask is adopted and the effluent liquid of the outflow port of the detector is respectively collected by being equally divided into n sections on the basis of the accumulated peak appearance time of the chromatographic peak. Labeling the n-stage effluents with L respectively₁、L₂、…、L_n. The above operation was repeated 10 times, and the effluent from each fraction collected was combined. Then, tetrahydrofuran was removed from the effluent of each stage by distillation at 80 ℃ to obtain n stages of resolved components, which were weighed separately. The number average molecular weight Mn and molecular weight distribution Mw/Mn of each stage of the resolved components are measured, and the weight percentage of each stage of the resolved components to the total weight of all n stages of the resolved components, i.e., the component ratio Y, is calculated.

2. Nuclear magnetic resonance analysis method

Operating the instrument: INOVA 500MHz NMR spectrometer manufactured by Varian corporation of America (¹H-NMR), solid dual resonance probe (5 mm).

The operating conditions are as follows: the operating temperature is room temperature, the number of scans nt is 1000, the chemical shift calibration δ tetramethylsilane is 0, the decoupling mode dm is nny (inverse gated decoupling), and the water lock field is heavy.

And (3) analyzing: subjecting the sample to¹And H-NMR characterization, namely analyzing a nuclear magnetic spectrum obtained correspondingly and calculating the average carbon number X of the side chain of the sample.

The following will specifically describe the procedure of analyzing the nuclear magnetic spectrum and the method of calculating the average carbon number X of the side chain, taking a methacrylate polymer, an acrylate polymer, a fumarate polymer, and an α -olefin polymer as examples, respectively, but the present invention is not limited thereto, and other polymers may be similarly analyzed and calculated with reference to the contents.

By way of example only, the methacrylate polymer or the acrylate polymer generally comprises structural units as shown below.

According to¹The significant difference in H-NMR spectra for methacrylate polymers can be roughly divided into H as shown in the figure for the hydrogen atoms in the structural units_A、H_B、H_C、H_DFour regions, and these regions have the relationship shown in formula (1). Due to H_CIs at chemical shift H_BIs covered with and H_DWhere it is more difficult to integrate, H can be_B、H_CAnd H_DAnd (6) combining and calculating. Therefore, the formula (1) can be transformed into the formula (2) and further derived as the formula (3).

In these formulas, X represents the side chain average carbon number of the methacrylate polymer.

Similar to the resolution of methacrylate polymers, the hydrogen atoms in the structural units can be roughly classified as H as shown in the figure_A、H_B、H_DIn the three regions, the average carbon number X of the side chain of the acrylate polymer can be calculated as shown in formula (4).

By way of example only, the fumarate polymers generally comprise structural units as shown below.

Similarly to the analysis of the methacrylate ester polymer, the average carbon number X of the side chain of the fumarate ester polymer can be calculated as shown in formula (5).

By way of example only, the α -olefin polymers generally comprise structural units as shown below.

Similarly to the analysis of the methacrylate polymer, the average carbon number X of the side chain of the α -olefin polymer can be calculated as shown in formula (6).

Specifically, for example, if a certain methacrylate polymer has the indicated nuclear magnetic spectrum and integral data, the average carbon number X of the side chain of the methacrylate polymer is 14.86 as calculated by formula (3).

In the following examples and comparative examples, properties of lubricant base oils a to F are shown in table a.

TABLE A

Base oil numbering	A	B	C
				Rank of	API-Ⅱ6	API-Ⅲ6	150SN
Viscosity at 100 deg.C	5.67	5.54	5.46
				V (viscosity m degree m2 means s-number 1)	112	121	90
Pour point/. degree.C	-18	-15	-15

Example A

113kg of a diluent oil (from Doxolone, 100N, same below) was charged into a mechanically stirred reactor under nitrogen, heated to 83-91 deg.C, and 270kg of a first monomer (decyl methacrylate/dodecyl methacrylate/tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate mixture, C: C)₁₀＝61％，C₁₂＝20％，C₁₄＝12％，C₁₆＝5％，C₁₈2%, X11.1), 1.35kg of benzoyl peroxide and 1.08kg of dodecyl mercaptan are added dropwise to the reactor while 150kg of a second monomer (a mixture of tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate/eicosyl methacrylate, where C is₁₄27% by weight, C₁₆＝42％，C₁₈＝24％，C₂₀7% by weight of a mixture B of X16.0), 0.75kg of benzoyl peroxide and 0.6kg of dodecylmercaptan are added dropwise to the reactor. At the initial moment of the dropwise addition, the ratio A/B of the amount (kg/hour) of the mixture A to the amount (kg/hour) of the mixture B was 4:1, and the sum of the two was 20 kg/hour, and then A/B was gradually decreased and the sum of the two was gradually increased until the moment of the dropwise addition for 3 hours, A/B reached 5:3, and the sum of the two reached 80 kg/hour. Then, the A/B is gradually reduced, the sum of the A/B and the B is gradually reduced until the dripping time is 6 hours, the A/B ratio reaches 1:2, the sum of the A/B and the B reaches 15 kg/hour, and the dripping is finished. Then, the reaction kettle is kept for 1 hour at 95 ℃, then 0.3kg of benzoyl peroxide and 113kg of diluent oil are added, the temperature is raised to 103 ℃ and kept for 2 hours, and then the polymerization reaction is finished, so that the gradient copolymer J1 is obtained. Here, the monomer conversion of the polymerization reaction was 99.1%, the number average molecular weight Mn of the gradient copolymer J1 was 47120, and the average carbon number X of the side chain was 12.5. Gradient copolymer J1 was used as a sample, and subjected to GPC resolution to obtain a 5-stage resolved fraction. The 5 split fractions were measured separately and are shown in table 1.

TABLE 1

Item	1	2	3	4	5
						Component ratio Y/%)	7.1	16.7	50	16.7	9.5
Average carbon number of side chain X	12.21	12.42	12.80	13.71	14.13
						Number average molecular weight Mn	21542	35411	48214	54525	65214

Example B

113kg of a diluent oil (obtained from Dilon corporation under the name 100N, the same applies below) was charged into a mechanically stirred reactor under nitrogen, heated to 83-91 deg.C, and 50kg of a first monomer (a mixture of hexyl methacrylate/octyl methacrylate/decyl methacrylate, where C is C₆＝71％，C₈＝21％，C₁₀8%, X6.6), 0.32kg benzoyl peroxide and 0.21kg dodecyl mercaptan was added dropwise to the kettle, while 370kg of the second monomer was added(mixture of lauryl methacrylate/tetradecyl methacrylate/hexadecyl methacrylate, wherein C₁₂55% by weight, C₁₄17% by weight, C₁₆28% by weight, X13.3), 1.8kg of benzoyl peroxide and 1.5kg of dodecylmercaptan are added dropwise to the reactor. At the initial moment of the dropwise addition, the ratio A/B of the amount (kg/hour) of the mixture A to the amount (kg/hour) of the mixture B was 7:1, and the sum of the two was 12 kg/hour, and then A/B was gradually decreased and the sum of the two was gradually increased until the moment of the dropwise addition for 3 hours, A/B reached 1:10, and the sum of the two reached 150 kg/hour. Then, the A/B is gradually reduced, the sum of the A/B and the B is gradually reduced until the dripping time is 6 hours, the A/B ratio reaches 1:20, the sum of the A/B and the B reaches 20 kg/hour, and the dripping is finished. Then, the reaction kettle is kept for 1 hour at 95 ℃, then 0.3kg of benzoyl peroxide and 113kg of diluent oil are added, the temperature is raised to 103 ℃ and kept for 2 hours, and then the polymerization reaction is finished, so that the gradient copolymer J2 is obtained. Here, the monomer conversion of the polymerization reaction was 98.3%, the number average molecular weight Mn of the gradient copolymer J2 was 45975, and the side chain average carbon number X was 12.0. The gradient copolymer J2 was used as a sample, and subjected to GPC resolution to obtain 8-stage resolved fractions. The 8 split fractions were measured separately and the results are shown in table 2.

TABLE 2

Item	1	2	3	4	5	6	7	8
									Component ratio Y/%)	4.2	5.9	8.5	9.6	43.1	14.4	8.4	6.0
Average carbon number of side chain X	7.30	9.84	11.17	11.82	12.44	12.65	12.70	12.89
									Number average molecular weight Mn	19542	25057	31124	38512	44215	47045	50215	59021

Comparative example A

A gradient copolymer was prepared as in example A, except that the first monomer and the second monomer were mixed uniformly and then added dropwise to the reaction system at a constant rate, specifically:

113kg of diluent oil are introduced into a mechanically stirred reactor under nitrogen, heated to 83-91 ℃ and 270kg of a first monomer (mixture of decyl methacrylate/dodecyl methacrylate/tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate, where C is C₁₀＝61％，C₁₂＝20％，C₁₄＝12％，C₁₆＝5％，C₁₈2%, X11.1), 150kg of a second monomer (a mixture of tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate/eicosyl methacrylate, where C is₁₄27% by weight, C₁₆＝42％，C₁₈＝24％，C₂₀7% by weight, X16.0), 2.1kg of benzoyl peroxide and 1.68kg of dodecylmercaptan are added dropwise at a constant rate of 70 kg/h, the dropwise addition being carried out for 6 hours, after the end of the dropwise addition, the reaction vessel is held at 95 ℃ for 1 hour, then 0.3kg of benzoyl peroxide and 113kg of diluent oil are added, the reaction is terminated after the temperature is raised to 103 ℃ for 2 hours, and the copolymer DJ1 is obtained. Here, the monomer conversion of the polymerization reaction was 99.3%, the number average molecular weight Mn of the copolymer DJ1 was 41768, and the side chain average carbon number X was 12.5. The copolymer DJ1 was used as a sample and subjected to GPC resolution to obtain 5 fractions as resolved fractions. The 5-stage split fractions were measured separately and the results are shown in Table 3.

TABLE 3

Item	1	2	3	4	5
						Component ratio Y/%)	13.2	17.5	30.0	21.1	18.2
Average carbon number of side chain X	12.41	12.54	12.54	12.47	12.40
						Number average molecular weight Mn	32154	39024	45145	52153	59213

Example C

Under nitrogen protection, 113kg of diluent oil (from Dilongyu, 100N, same below) was charged into a mechanically stirred reactor, heated to 83-91 deg.C, and 150kg of a first monomer (decyl methacrylate/dodecyl methacrylate)Mixture of C₁₀＝50％，C₁₂50%, X10.9), 0.75kg benzoyl peroxide and 0.7kg dodecyl mercaptan were added dropwise to the kettle, and 100kg of a second monomer (dodecyl methacrylate/tetradecyl methacrylate mixture, where C is C) was added dropwise at a constant rate while maintaining the feed rate of the first monomer mixture at 10 kg/hr for the first 4 hours₁₂70% by weight, C₁₄30%, X12.5), 0.6kg benzoyl peroxide and 0.55kg dodecyl mercaptan were added dropwise to the kettle. At the initial moment of the dropwise addition, the ratio A/B of the amount of mixture A added in drops (kg/hour) to the amount of mixture B added in drops (kg/hour) was 2:1, the sum of which was 15 kg/hour, then B was gradually increased, the sum of which was gradually increased until 4 hours of dropwise addition, A/B reached 1:3, the sum of which reached 80 kg/hour, at which time the second monomer feed was terminated, at which time 170kg of a third monomer (a mixture of tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate mixture, in which C was C₁₄64% by weight, C₁₆＝25％，C₁₈And (3) adding a mixture C of 11 percent, 14.8 percent, 0.8kg of benzoyl peroxide and 0.7kg of dodecyl mercaptan dropwise into the reaction kettle, wherein the ratio of the dropwise adding amount (kg/hour) of the mixture A to the dropwise adding amount (kg/hour) of the mixture C is 1:2, the sum of the A and the C is 100 kg/hour, then the A is gradually reduced, the sum of the A and the C is gradually reduced until the dropwise adding is continued for 5 hours, the A/C reaches 1:3, the sum of the A and the C reaches 10 kg/hour, and the dropwise adding is finished. Then, the reaction kettle is kept for 1 hour at 95 ℃, then 0.5kg of benzoyl peroxide and 113kg of diluent oil are added, the temperature is raised to 103 ℃ and kept for 2 hours, and then the polymerization reaction is finished, so that the gradient copolymer J3 is obtained. Here, the monomer conversion of the polymerization reaction was 99.6%, the number average molecular weight Mn of the gradient copolymer J3 was 52120, and the side chain average carbon number X was 11.8. Gradient copolymer J3 was used as a sample, and subjected to GPC resolution to obtain a 5-stage resolved fraction. The 5-stage split fractions were measured separately and the results are shown in Table 4.

TABLE 4

Item	1	2	3	4	5
						Component ratio Y/%)	8.2	24.5	38.8	22.4	6.1
Average carbon number of side chain X	11.70	11.91	12.36	13.68	13.90
						Number average molecular weight Mn	20023	35289	50317	62527	74924

Example D

5 different linear alkyl methacrylate monomer mixtures A to E were prepared, and the compositions of the respective mixtures are shown in Table 5.

TABLE 5

Under the protection of nitrogen, 113kg of diluent oil (purchased from Bilongong company, brand 100N, the same below) was added into a reaction kettle equipped with a mechanical stirrer, the mixture A was heated to 92-100 ℃ at the initial time of the dropwise addition, the mixture A was added into the reaction kettle at a constant rate of 10 kg/hr, simultaneously, the mixture B was added dropwise at a rate of 5 kg/hr, the feed rate of the mixture B was gradually increased, when 2 hours were reached, the feed of the mixture A and the mixture B was terminated, then the mixture C and the mixture D were added into the reaction kettle dropwise, the ratio C/D of the amount of the mixture C added dropwise (kg/hr) to the amount of the mixture D added dropwise (kg/hr) was 3:1, the sum of the two was 60 kg/hr, then C was gradually decreased, the mixture D was gradually increased, the sum of the two was gradually increased until the time of 5 hours, and C/D reaches 1:1, the sum of the two reaches 130 kg/h, at the moment, the dropping of the mixture C is finished, then the mixture E is dropped into the reaction kettle, at the moment, the ratio D/E of the dropping amount (kg/h) of the mixture D to the dropping amount (kg/h) of the mixture E is 10:1, the sum of the two is 130 kg/h, then D is gradually reduced, the sum of the two is gradually reduced until the dropping time is 7 hours, D/E reaches 1:1, the sum of the two reaches 13 kg/h, and the dropping is finished. Then, the reaction kettle is kept for 1 hour at the temperature of 100 ℃, then 0.3kg of benzoyl peroxide and 113kg of diluent oil are added, the temperature is raised to 103 ℃ and kept for 2 hours, and then the polymerization reaction is finished, so that the gradient copolymer J4 is obtained. Here, the monomer conversion of the polymerization reaction was 99.2%, the number average molecular weight Mn of the gradient copolymer J4 was 39120, and the side chain average carbon number X was 12.14. The gradient copolymer J4 was used as a sample, and subjected to GPC resolution to obtain 8-stage resolved fractions. The 8 split fractions were measured separately and the results are shown in table 6.

TABLE 6

Item	1	2	3	4	5	6	7	8
									Component ratio Y/%)	3.2	6.3	11.9	15.1	26.2	23.8	11.1	2.4
Average carbon number of side chain X	8.00	9.64	12.05	12.00	12.23	13.16	13.50	14.13
									Number average molecular weight Mn	18154	25124	30147	34987	37651	40154	49872	58326

Gradient copolymers J1 to J4 and copolymer DJ1 were added to the base oil in the amounts specified in Table 7, respectively. The amount of each copolymer, the type of base oil, and the pour point depressing test results obtained are shown in Table 7.

TABLE 7

As can be seen from the results obtained in the comparative examples and comparative examples, the gradient copolymer obtained in the present invention exhibits excellent pour point depressing effect on a variety of lubricant base oils. Moreover, even if the addition amount is very small, the pour point of the lubricating oil base oil is still obviously reduced, which shows that the gradient copolymer obtained by the invention also has a remarkable pour point reducing effect.

Example E

113kg of a diluent oil (obtained from Dilongyu Co., Ltd., trade name 100N, the same applies hereinafter) was charged into a mechanically stirred reaction vessel under nitrogen protection, heated to 83-91 ℃ and 270kg of a first monomer [ decyl methacrylate/dodecyl methacrylate/tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate (C) was added at a steady rate of 50 kg/hr₁₀＝28％，C₁₂＝32％，C₁₄＝28％，C₁₆＝8％，C₁₈＝4％)，X＝12.3]A mixture A 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 then the addition rate was linearly decreased so that the flow rate was reduced to 30 kg/hour when the total feed time was 6 hours. 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/h₁₄＝38％，C₁₆＝20％，C₁₈＝25％，C₂₀＝17％，X＝16.2]A mixture B of 0.75kg of benzoyl peroxide and 0.6kg of dodecyl mercaptan was added dropwise to the reaction vessel, the amount of the mixture B added being linearly increased such that the flow rate was increased to 30 kg/hr when the total feeding time was 3 hours, and then the flow rate was maintained to feed for 3 hours. A. And when the mixture B is dropwise added, continuously keeping the temperature of 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, thus obtaining the lubricating oil pour point depressant J5, wherein the monomer conversion rate in the lubricating oil pour point depressant J5 is 99.1%, the number average molecular weight of the gradient copolymer J5 is 40120, and the average carbon number X of a side chain is 13.5. Gradient copolymer J5 was used as a sample, and subjected to GPC resolution to obtain a 5-stage resolved fraction. The 5-stage split fractions were measured separately and the results are shown in Table 8.

TABLE 8

Item	1	2	3	4	5
						Component ratio Y/%)	17.0	19.5	28.4	18.2	16.8
Average carbon number of side chain X	12.90	13.21	13.54	13.83	14.01
						Number average molecular weight Mn	25987	34561	41250	48647	57854

Example F

113kg of diluent oil were added to 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 added at an initial rate of 40 kg/hour₈＝12％，C₁₀＝15％，C₁₂＝48％，C₁₄＝25％)，X＝11.5]A mixture A of 0.9kg of benzoyl peroxide and 0.7kg of dodecylmercaptan is added to the reactor and then slowly reduced linearly so that when the total feed time is 3 hours, the flow is reduced to 32 kg/hour, withThe latter line decreased rapidly so that the flow rate decreased to 10 kg/hour when the total feed time was to 6 hours. 255kg of a second monomer [ tetradecyl methacrylate/hexadecyl methacrylate/octadecyl methacrylate/eicosyl methacrylate (C14 ═ 38%, C) was simultaneously added dropwise at an initial rate of 20 kg/h₁₆＝20％，C₁₈＝25％，C₂₀＝17％，X＝16.2]A mixture B of 0.9kg of benzoyl peroxide and 0.7kg of dodecylmercaptan was added 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 50 kg/hour, and then the flow rate was maintained for feeding 3 hours. A. And when the addition of the mixture B is finished, continuously keeping the temperature of 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 the lubricating oil pour point depressant J6, wherein the monomer conversion rate of the lubricating oil pour point depressant J6 is 99.4 percent, the number average molecular weight is 41702, and the average carbon number X of a side chain is 14.0. Gradient copolymer J6 was used as a sample, and subjected to GPC resolution to obtain a 5-stage resolved fraction. The 5-stage split fractions were measured separately and the results are shown in Table 9.

TABLE 9

Item	1	2	3	4	5
						Component ratio Y/%)	18.8	16.5	25.3	20.3	19.2
Average carbon number of side chain X	12.81	13.30	14.00	14.86	15.10
						Number average molecular weight Mn	23781	34217	41702	51514	59248

Examples 1-6 and comparative examples 1-7 of lubricating oil compositions for gasoline engines

The sources of additives used in the examples and comparative examples of lubricating oil compositions are shown in Table 10.

Watch 10

Name (R)	Source
		Amorphous ethylene-propylene copolymer finger adhesive LZ7065	Lubrizol Ltd
Hydrogenated styrene-isoprene adhesive SV260	Infineum Corp
		Semi-crystalline ethylene-propylene copolymer tackifier, Paratone 8421	Chevron Oronite Corp
Alkylated diphenylamine T534	Beijing Xinpu Fine chemical technology development Co
		Phenolic ester type antioxidant L135	BASF AG

The formulation compositions of examples 1-6 and comparative examples 1-7 of gasoline engine lubricating oil compositions are shown in Table 11. The components are added into a blending container according to the proportion, heated at the normal pressure of 45-80 ℃, stirred for 1-2 hours, and the SN/GF-5 gasoline engine lubricating oil composition with the viscosity grade of 5W-30 is prepared.

These lubricating oil compositions were subjected to aging tests using ROBO test method (ASTM D7528) to simulate iii GA engine test conditions to obtain aged oils. MRV low temperature pumpability measurements of lubricating oil samples before and after aging, including yield stress and low temperature pumpability, were performed using the method of ASTM D4684. In the III GA engine test, the CCS low-temperature dynamic viscosity of the old oil is firstly measured, if the CCS of the old oil meets the requirement of the original viscosity grade, the MRV low-temperature pumpability is measured at the test temperature of the original viscosity grade, otherwise, the MRV is measured at the test temperature of the next higher viscosity grade (higher by 5 ℃). In order to compare test results at the same level, the MRV low temperature pumpability measurements of the aged used oils of the lubricating oil compositions of the present invention were conducted at a temperature that was 5 ℃ higher than the original viscosity grade test temperature.

The low temperature pumpability of the lubricating oil composition is acceptable if the MRV low temperature pumpability of the test samples (including virgin and aged oils) is not greater than 60000 mPas and no yield stress (yield stress < 35 Pa). The test results are shown in Table 12.

TABLE 11

The oxidation induction period of the oil product is measured by using ASTM D4742 thin layer oxidation test (TFOUT), the oxidation resistance of the oil product is evaluated, and the longer the induction period is, the better the oxidation resistance of the oil product is. The results of the oxidation induction periods for the oils of examples 1-6 and comparative examples 6-7 and the SN/GF-55W-30 market are shown in Table 13.

As can be seen from the results of tables 12 and 13, the lubricating oil compositions of the present invention have very excellent low-temperature pumping performance and antioxidant performance.

TABLE 12

Watch 13

Oil sample	TFOUT/min
		Example 1	153
Example 2	156
		Example 3	148
Example 4	160
		Example 5	158
Example 6	162
		Comparative example 6	126
Comparative example 7	130
		SN/GF-55W-30 market oil	141

Claims

1. A gasoline engine lubricating oil composition comprising a gradient copolymer, a viscosity index improver, a dispersant, a detergent, zinc dialkyldithiophosphate, dialkyldithiocarbamate and/or dialkyldithiocarbamate, an antioxidant, a friction modifier and a lubricating oil base oil, the method for producing the gradient copolymer comprising: a step of adding at least two monomers to a polymerization reaction system to cause addition copolymerization of the at least two monomers, wherein the at least two monomers each independently represent a compound represented by formula (I) and/or a mixture thereof,

in the formula (I), the compound represented by the formula (I),

radical R₁Represents H or

Radical R₂Represents H or C_1-4A linear or branched alkyl group,

the symbol a represents either 0 or 1,

the radical R' represents H or the radical R₃，

Radical R₃Represents C₁-C₃₀A linear or branched alkyl group,

setting the initial time of adding the at least two monomers into the polymerization reaction system as t₀The termination time is t_mThe monomer addition time of the at least two monomers is t, t ═ t_m-t₀When the monomer addition time is divided into m equal parts, the symbol m represents a closed interval [5, ∞ ]]An integer of (a) at any monomer addition time t_xThe relative proportions of the at least two monomers added to the polymerization system being such that the average number of carbon atoms in the side chain X is the average number of carbon atoms in the NMR of a mixture of the at least two monomers in the relative proportions_xSatisfying the following relationship, the symbol x represents any integer from 0 to m,

X₀<X₁<…<X_m-1<X_m (V)

wherein the termination time t of the monomer addition is set_mThe sum of the cumulative addition amounts of the at least two monomers to the polymerization reaction system within the monomer addition time is G, and is set at any monomer addition time t_xThe sum of the addition amounts of the at least two monomers to the polymerization reaction system is G_xThe symbol x represents an arbitrary integer from 0 to m, and the following relational expression holds,

G₀/G<G₁/G<…<G_j/G>…>G_m-1/G>G_m/G (VI)

in formula (VI), the symbol j represents a closed interval [ m/4, 3m/4 ]]An integer of (a), and G₀+G₁+…+G_j+…+G_m-1+G_m＝G。

2. Lubricating oil composition according to claim 1, characterised in that the group R₁Represents H, a radical R₂Represents H or methyl, the symbol a represents 1, the radical R' represents the radical R₃Radical R₃Represents C₆-C₂₄A linear or branched alkyl group; symbol m represents a closed interval [8, ∞ ]]An integer within; from X₀To X_mGradually increasing; the symbol j represents a closed interval [ m/3, 2m/3 ]]An integer within; from G₀G to G_jG is gradually increased from G_jG to G_mthe/G gradually decreases.

3. Lubricating oil composition according to claim 1, characterised in that the group R₃Represents C₆-C₂₀A linear alkyl group, the upper limit of the integer represented by the symbol m is 20000, 10000, 5000, 1000, 500, 200, 100 or 50; the symbol j represents a closed interval [2m/5, 3m/5 ]]An integer within; from G₀G to G_jLinear increase of/G from G_jG to G_mthe/G decreases linearly.

4. Lubricating oil composition according to claim 1, wherein G is_xG and X_xThe following relational expression is satisfied,

in formula (VII), symbol μ represents any one value within the open interval (12.5, 14.2), and symbol σ represents any one value within the open interval (0.5, 2).

5. Lubricating oil composition according to claim 4, characterised in that the symbol μ represents any value within the open interval (12.6, 13.8).

6. Lubricating oil composition according to claim 1, wherein the group R is represented by moles₃Represents C₁₀-C₁₈The proportion of the compounds of formula (I) having a linear or branched alkyl group to the total amount of monomers is from 40% to 95%.

7. Lubricating oil composition according to claim 1, wherein the group R is represented by moles₃Represents C₁₀-C₁₈The proportion of the compounds of formula (I) having a linear or branched alkyl group to the total amount of monomers is from 55 to 95%.

8. The lubricating oil composition according to claim 1, wherein X is₀Represents a closed interval [6.5, 12.5 ]]Or said X is any one of the values in_mRepresents a closed interval [13.8, 19.5 ]]Any one of the values in (b).

9. The lubricating oil composition according to claim 1, wherein X is₀Represents a closed interval [7.8, 12.0 ]]Or said X is any one of the values in_mRepresents a closed interval [14.5, 18.2 ]]Any one of the values in (b).

10. Lubricating oil composition according to claim 1, wherein the ratio G_jG is from 20% to 75%, or the ratio G₀G or the ratio G_mthe/G is from 0.01% to 20%.

11. Lubricating oil composition according to claim 1, wherein the ratio G_jG is from 25% to 65%, or the ratio G₀G or the ratio G_mThe ratio of/G is 0.1% to 10%.

12. The lubricating oil composition according to claim 5, wherein the reaction temperature of the copolymerization reaction is from 50 ℃ to 180 ℃, the reaction time of the copolymerization reaction is from 1 hour to 24 hours, and the monomer addition time t is from 0.5 hour to 12 hours.

13. The lubricating oil composition according to claim 1, wherein the reaction temperature of the copolymerization reaction is from 55 ℃ to 165 ℃, the reaction time of the copolymerization reaction is from 1.5 hours to 20 hours, and the monomer addition time t is from 1 hour to 10 hours.

14. Lubricating oil composition according to any one of claims 1 to 13, wherein the gradient copolymer comprises from 0.01% to 2% by weight of the total lubricating oil composition; the viscosity index improver accounts for 0.1-25% of the total mass of the lubricating oil composition; the dispersant accounts for 0.5 to 15 percent of the total mass of the lubricating oil composition; the detergent accounts for 0.1-10% of the total mass of the lubricating oil composition; the addition amount of the zinc dialkyl dithiophosphate in the lubricating oil composition is not more than 0.08 percent in terms of the mass fraction of phosphorus; the dialkyl dithiocarbamate and/or the dialkyl dithiocarbamate accounts for 0.05 to 1.5 percent of the total mass of the lubricating oil composition; the antioxidant accounts for 0.1-6% of the total mass of the lubricating oil composition; the friction modifier accounts for 0.01-5% of the total mass of the lubricating oil composition; the lubricant base oil constitutes the main component of the lubricating oil composition.

15. Lubricating oil composition according to any one of claims 1 to 13, wherein the gradient copolymer comprises from 0.05% to 1.5% by weight of the total lubricating oil composition; the viscosity index improver accounts for 0.5 to 20 percent of the total mass of the lubricating oil composition; the dispersant accounts for 1-12% of the total mass of the lubricating oil composition; the detergent accounts for 0.2 to 6 percent of the total mass of the lubricating oil composition; the adding amount of the zinc dialkyl dithiophosphate in the lubricating oil composition is 0.06-0.08 percent by mass of the phosphorus element; the dialkyl dithiocarbamate and/or the dialkyl dithiocarbamate accounts for 0.1 to 1.2 percent of the total mass of the lubricating oil composition; the antioxidant accounts for 0.2-3% of the total mass of the lubricating oil composition; the friction modifier accounts for 0.02-2% of the total mass of the lubricating oil composition; the lubricant base oil constitutes the main component of the lubricating oil composition.

16. Lubricating oil composition according to any one of claims 1 to 13, characterised in that the viscosity index improver is selected from amorphous ethylene propylene copolymers, polymethacrylates, polyalkylmethacrylates, methacrylate copolymers, copolymers of styrene and acrylates, hydrogenated or partially hydrogenated copolymers of styrene/isoprene, styrene/butadiene, isoprene/butadiene, partially hydrogenated homopolymers of butadiene and isoprene, isoprene/divinylbenzene; the dispersant is selected from one or more of mono-polyisobutylene succinimide, di-polyisobutylene succinimide, high molecular polyisobutylene succinimide, boronized polyisobutylene succinimide and polyisobutylene succinate; the detergent is selected from one or more of a sulphonate, an alkyl salicylate and a sulphurised alkyl phenate; the alkyl group in the zinc dialkyl dithiophosphate is C₂-C₁₂Alkyl groups of (a); the alkyl in the dialkyl dithiocarbamate and/or the dialkyl dithiocarbamate is C₂-C₁₂Alkyl groups of (a); the antioxidant is selected from one or more of phenol type antioxidant, amine type antioxidant, phenolic ester type antioxidant and sulfophenolic ester type antioxidant; the friction modifier is selected from an ashless friction modifier and/or an oil-soluble organo-molybdenum friction modifier; the lubricating oil base oil is selected from one or more of API I base oil, II base oil, III base oil, IV base oil and V base oil.

17. A method of making a gasoline engine lubricating oil composition comprising the step of mixing the various additives set forth in any one of claims 1-16 with a lubricating base oil.