JP2010520319A - Engine lubricant - Google Patents

Abstract

An object of the present invention is to provide an engine lubricant that is particularly useful for use in a four-stroke engine.
Engine lubricants, in particular SAE 0W engine lubricants, are described. This engine lubricant is an engine lubricant containing at least one diester of 15% by mass or more and an additive of 20% by mass or less, provided that the at least one diester or more than one is present. An engine lubricant in which the mixture has a kinematic viscosity of 3.3 or less at 100 ° C, a viscosity index of 130 or more, a pour point of -30 ° C or less, and a Noack evaporation loss of 15% by mass or less.
[Selection figure] None

Description

  The present invention relates to engine lubricants, particularly engine lubricants used in four-stroke engines, and more preferably engine lubricants having a SAE classification of less than SAE 5 W, and the use of such lubricants in four-stroke engines. About.

  Due to the increasing environmental, legal and economic pressures, engine lubricants increase engine efficiency, i.e. greater mpg or kpl, and reduce engine emissions, and the frequency of lubricant changes There is a need to contribute to a reduction in the use of less oil.

  However, especially when petroleum-derived oils, such as mineral oils, are used as lubricants, these requirements impose requirements that contradict the viscosity and volatility properties exhibited by these oils, so that these requirements are met. It is difficult. For example, engine oils are required to easily start a cold engine when ambient temperature is low, while ensuring good lubrication at high operating temperatures. This can be achieved by mixing lubricant feedstocks of different viscosities. However, such a formulation may not be sufficient to meet the operating temperature range requirements due to the different viscosity indices of the component lubricant stock. This leads to the use of viscosity index improvers and often leads to relatively large amounts. Such viscosity index improvers are often polymeric in nature and can be destroyed by operating temperatures and fluid shear in the engine, particularly in high performance vehicles, and potential loss of viscosity and Cause engine failure.

  Other efforts include synthetic lubricant feedstocks such as specially treated mineral oils, alpha olefin oligomers and polymers (hereinafter polyalphaolefins) and esters, such as monoesters, diesters, polyesters and complex esters, optionally Used with suitable additives such as viscosity index improvers.

  Such an approach is described in, for example, German Patent Application No. 2133042, European Patent Application Publication No. 0089709, European Patent No. 079334, Japanese Patent Application Laid-Open No. 05-331483, US Pat. No. 4,155,861. Illustrated in the specification and US Pat. No. 6,303,548.

  German Offenlegungsschrift 2133042 discloses engine lubricants with a viscosity classification of 10W-20 to 5W-20, which have a viscosity index in the range of 80 to 105 and 7.5 cSt at 100 ° C. A mineral oil raffinate having a kinematic viscosity in the range of ˜12 cSt, an oil soluble synthetic lubricant having a kinematic viscosity in the range of 3 cSt to 5 cSt at 100 ° C. and a Noack evaporation loss of 3% to 10%, such as diesters, And consists of additives. A specific example of a 10 W engine oil having a kinematic viscosity of 7 sSt at 100 ° C. and a viscosity index of 116 and having a 5% additive package is 75% kinematic viscosity of 9 cSt at 100 ° C., Derived from a mineral oil with a viscosity index of 102 and 6% Noack evaporation loss, and 25% di-n-decanol trimethyladipate.

  EP 0089709 discloses organic carbonic acid diesters derived from alcohols as components of engine lubricants.

  EP 0 792 334 describes at least one derivative derived from a saturated branched aliphatic monohydric alcohol having at least 8 carbon atoms and a saturated branched aliphatic monocarboxylic acid having at least 10 carbon atoms. Engine lubricants having the following esters are disclosed.

  Japanese Patent Application Laid-Open No. 05-331483 discloses an engine oil that requires only a small amount of a viscosity index improver. This engine oil contains 10% to 30% diester or polyester, 60% to 89% alpha olefin oligomer, 1% to 20% ethylene alpha olefin oligomer and 0.5% to 3% zinc dialkyldithiophosphate. It has as an agent. This oil has a kinematic viscosity of 4 cSt or higher at 100 ° C. A specific example includes diisodecyl adipate having a kinematic viscosity of 3.62 cSt at 100 ° C.

  U.S. Pat. No. 4,155,861 describes a lubrication based on mixed esters comprising diesters of dicarboxylic acid monomers and complex esters derived from dicarboxylic acids (preferably branched) and hexanediol or trimethylhexanediol. Agents are disclosed. In a specific example, the monomeric diester is n-octyl trimethyladipate, n-decyl trimethyladipate. Addition of complex esters to levels of 1% to 10% of n-octyl trimethyladipate, n-decyl, is described to give SAE class 5W / 20, 5W / 30 or 10W / 40 engine oils. .

  U.S. Pat. No. 6,303,548 discloses SAE 0W-40 lubricant composition, which is 5% to 80% mineral oil base stock, 3.5 cSt to 4.5 cSt at 100 <0> C. 5% to 90% polyalphaolefins with kinematic viscosities ranging from 1% to 30% esters derived from monocarboxylic acids and polycarboxylic acids with monohydric alcohols and polyols, and further 3% to 7 % Polymethacrylate and 4-9% olefin copolymer or hydrogenated diene copolymer. A specific example uses diisooctyl adipate.

  Disadvantages of such lubricants include increased inherent limits and volatility (ie, lubricant Noack evaporation loss) given by the base oil viscosity index (which affects film thickness). It is mentioned that the viscosity cannot be reduced without this. In addition, very low viscosity esters may also have high polarity, and if these esters are used at high usage, eg, greater than 15% by weight, they may compete with antiwear agents such as ZDDP. This can lead to seal compatibility problems and potential wear problems. For example, diisooctyl adipate has an NPI of 41. In addition, low viscosity lubricants that are optimized to give low volatility also have a low viscosity index (less than 125) resulting from poor oxidative stability (due to the use of components with gem-branches), Either poor cold flow properties or short exchange intervals can be plagued.

German Patent Application No. 2133042 European Patent Application Publication No. 0089709 European Patent No. 0792334 Japanese Patent Application Laid-Open No. 05-331483 U.S. Pat. No. 4,155,861 US Pat. No. 6,303,548

  It is an object of the present invention to provide an engine lubricant that is particularly useful for use in a four stroke engine. It is a further object of the present invention to provide an engine lubricant having a SAE classification of less than 5 W, more preferably a SAE classification of 0 W or less.

  According to the present invention, the engine lubricant comprises at least 15% by weight of at least one diester and up to 20% by weight of an additive, if there is at least one diester or more than one. For example, the mixture of diesters has a kinematic viscosity of not more than 3.3 at 100 ° C., a viscosity index of not less than 130, a pour point of not more than −30 ° C., and a Noack evaporation loss of not more than 15% by mass.

  The present invention provides an engine lubricant that is particularly useful for use in a four-stroke engine.

  The term “mass%” as used herein in the context of the invention described and claimed herein is expressed as a percentage of the total mass of engine lubricant, as required by the context. It represents the mass% of that component. When referring to a particular component in context, for example, Noack evaporation loss, the term “mass%” represents mass% relative to the total mass of that component.

  Preferably, the engine lubricant comprises 90% by weight or less of the at least one diester. In one aspect of the invention, the engine oil consists essentially of the at least one diester and the additive.

  Preferably, the engine lubricant comprises 20% by weight or more, more preferably 25% by weight or more of the at least one diester. The engine lubricant may contain 75% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less of the at least one diester. In one embodiment of the invention, the engine lubricant comprises about 30% by weight of the at least one diester.

Where the engine lubricant does not consist essentially of the at least one diester and the additive, the remainder of the engine lubricant is an API Group III, IV and V lubricant. And a gas liquefied lubricant (GTL) and mixtures thereof. An example of a suitable Group III lubricant is mineral oil. Examples of lubricants suitable group IV _includes a polyalphaolefin derived from alpha olefins C 8 _{-C 12,} also has a kinematic viscosity in the range of 3.6cSt~8cSt at 100 ° C. Yes. Examples of Group V lubricants include alkyl naphthalenes, alkyl benzenes, and esters such as esters derived from monohydric alcohols and / or polyols and mono- or polycarboxylic acids. Examples of alkylnaphthalenes include Cinestick ™ 5 and Cinestick ™ 12 alkylnaphthalenes available from Mobil. Examples of esters are the Priolube 1976 ™ monoester and the Priolube 3970 ™ TMPnC ₈ / nC ₁₀ polyol ester. GTL base stocks are higher molecular weight molecules via conversion of natural gas (ie methane and higher alkanes) to synthesis gas (carbon monoxide and hydrogen) and subsequent oligomerization (eg, Fischer-Tropsch process). This high molecular weight molecule is hydrocracked to produce isoparaffins in the desired lubricant boiling / viscosity range. GTL base stocks are only recently commercialized and therefore there is very little or no data freely available in this connection. As far as is known, such GTL-based feedstocks will have a viscosity grade similar to polyalphaolefins.

  In one aspect of the present invention, the engine lubricant comprises the at least one diester, at least one Group V lubricant, preferably an alkyl naphthalene or an ester other than the at least one diester, such as It consists essentially of a polyol ester or complex ester and the aforementioned additives.

  Preferably, the at least one diester has a kinematic viscosity at 100 ° C. of 3.0 cSt or less. Preferably, the at least one diester has a viscosity index of 140 or less. Preferably, the at least one diester has a pour point of about −30 ° C. or lower, more preferably −35 ° C. or lower, and especially −40 ° C. or lower. Preferably, said at least one diester has a Noack evaporation loss of 14.5% by weight or less, more preferably 14.0% by weight or less.

  Preferably, said at least one diester has a flash point of 200 ° C. or higher, more preferably 210 ° C. or higher, more preferably 220 ° C. or higher, and especially about 230 ° C.

  Preferably, said at least one diester has a non-polarity index (NPI) of greater than 30 to less than 100, more preferably less than 80, as described in EP 0 792 334. .

  Preferably, said at least one diester is also stable when kept at -20 ° C for 1 week. The low temperature stability is determined by storing approximately 30 mL of diester in a glass bottle and leaving the bottle in a -20 ° C. freezer for a week, examining the sample at regular intervals, and forming crystals or It can be tested by noting the signs of gelation.

  Preferably, the at least one diester has a cold crack simulation test (CCS) kinematic viscosity at −35 ° C. of 6200 cPs or less.

  Preferably, the engine lubricant contains only one of the at least one diester.

  If the engine lubricant contains at least two of the at least one diester, each diester can be selected with different properties. Preferably, the properties of each diester are in the range of property values as described above, or if the properties of the diester mixture are within the range of property values described above, one of the at least one diester Or more characteristics may be outside the range of the above characteristic values.

Preferably, said at least one diester is:
a) at least one C ₅ -C ₁₂ , preferably C ₆ -C ₁₀ aliphatic dicarboxylic acid or anhydride thereof, and at least one primary or secondary, preferably primary C Reaction product of _{7 to} C ₁₂ , preferably C _{8 to} C ₁₀ aliphatic primary alcohol (if the at least one acid is branched, the at least one alcohol is a chain, if if at least one acid is linear above, in which case at least one alcohol of the is obtained by branching), and b) at least one C ₅ -C _12, preferably the at least one polyalkylene glycol and aliphatic monocarboxylic acids C ₆ -C ₁₀ (the alkyl group is selected from C ₂ -C ₄ alkyl groups and mixtures thereof) Reaction product (wherein said at least one polyalkylene glycol contains at least one repeating unit which is a branched methyl group, at least one said at least one acid is linear; Also, if the at least one polyalkylene glycol contains only linear repeating units, at least one of the at least one acid is branched),
Selected from the group consisting of

  Preferably, when the diester is derived from dibasic acids or their anhydrides and primary alcohols, the diester is 17-36, more preferably 20-30, and even more preferably 23-26 carbons. Contains atoms.

  Preferably, when the diester is derived from a monobasic acid and a polyalkylene glycol, the diester contains 17 to 40, more preferably 20 to 30 carbon atoms.

  Preferably, the reaction product of a dicarboxylic acid and an alcohol is either a branched acid and a linear alcohol reaction product, or a linear acid and a branched alcohol reaction product.

  Preferably, the reaction product of a monocarboxylic acid and a polyalkylene glycol is a reaction product of a branched acid and polyethylene glycol, or a linear acid and polypropylene glycol or polybutylene glycol, preferably polypropylene glycol, Or any of the reaction products with those copolymers containing at least one ethylene glycol repeat unit. Preferably, the polyalkylene glycol has an average relative molecular mass (avRMM) in the range of approximately 150-300, more preferably in the range of approximately 180-250. A preferred polyalkylene glycol is polypropylene glycol.

Branched branched acids and / or branched alcohols, C ₁ -C ₄ alkyl groups, more preferably C ₁ -C ₂ alkyl group, and particularly can be a methyl group. The branched acid is preferably not branched at the alpha position, but is preferably branched at the beta position. Preferably, the acid does not contain any gem-branching groups, such as gem-dimethyl or gem-diethyl groups, and preferably only one or only two branched chains, preferably a single in the beta position. Contains a branched chain.

  Preferred dicarboxylic acids include adipic acid, 3-methyladipic acid and sebacic acid. Preferred primary alcohols include 1-octanol, 1-decanol and mixtures thereof, 2-ethylhexanol and isononyl alcohol. Preferred monocarboxylic acids include caprylic acid and capric acid. Preferred polyalkylene glycols preferably consist of polypropylene glycol having an avRMM in the range of 180-250.

  Preferred diesters are selected from the group consisting of diisononyl adipate, di-n-octyl 3-methyl-adipate, di-2-ethylhexyl sebacate and PPG225 n-octyl, n-decyl diester and mixtures thereof. More preferably, the diester is selected from the group consisting of diisononyl adipate, di-n-octyl 3-methyl-adipate and di-2-ethylhexyl sebacate and mixtures thereof.

  As expected, the acids and alcohols used to make the diesters are from commercial sources and need not contain 100% acid or alcohol. Such commercial products usually contain other isomers and / or additional products of short or long chain length, along with the main components of the main product. This can lead to fluctuations in the properties of the reaction product diester. Such variation in properties is illustrated in the examples below.

  In one aspect of the invention, the engine lubricant may optionally include simple esters, diesters that are not diesters previously described, and complex esters or mixtures thereof. Preferably, the mass ratio of the diester to the optional ester is in the range of 100: 0 to 60:40, more preferably in the range of 100: 0 to 75:25, even more preferably 99: 1 to 80:20. In the range of 95: 5 to 85:15.

  As described above, the engine lubricant according to the present invention contains 20% by mass or less of an additive. Preferably, the engine lubricant includes an additive of 15% by mass or less, more preferably 10% by mass or less.

Usually, the additive is
a) Viscosity index improvers such as alkyl methacrylate copolymers, olefin copolymers (OCP) and mixtures thereof (these are effective amounts, usually in the range of 0.1% to 6% by weight) are added. )
b) antioxidants, such as phenolic antioxidants, such as hindered phenols, and alkylated diphenylamines and mixtures thereof (these are effective amounts, usually in the range 0.5% to 1% by weight). )
c) Metal deactivators such as metal salts of dialkyldithiophosphates, thiadiazole and riasol (which may also function as corrosion inhibitors and extreme pressure additives) (these are effective amounts, usually 0.01 mass% to 0.5 mass% is added)

d) Pour point depressants (these are added in effective amounts, usually 0.1% to 1.0% by weight)
e) Extreme pressure additives such as zinc diaryldithiophosphate (ZDDP) (these are added in effective amounts, usually in the range of 0.5% to 3.0% by weight)
f) Friction modifiers such as glycerol monooleate (these are added in effective amounts, usually in the range of 0.3% to 1.3% by weight)

g) Antifoaming agents such as dimethylpolysiloxane, polyacrylates (these are added in effective amounts, usually from 1 ppm to 100 ppm)
h) Multifunctional additives, such as DDI (cleaner dispersion prevention) packages, and i) mixtures of such additives.

  In the engine lubricant according to the present invention, the above-mentioned diesters and optionally other esters are present in a significant amount, preferably as the main component of the engine lubricant, such engine lubricants such as viscosity index improvers and the like. There may be no additives.

  The combination of additives used in engine lubricants and their amounts can vary widely, however, the total amount of all additives contained in the engine lubricant according to the invention is as described above. The upper limit is 20% by mass, more preferably 15% by mass, and still more preferably 10% by mass.

  The present invention includes the use of the engine lubricant described herein in lubricating a four-stroke engine, and lubrication of the engine with the engine lubricant described herein. Includes methods.

  The present invention further includes a SAE 0W engine lubricant, which includes at least one diester as described herein. The features and embodiments described herein also apply to the SAE 0W engine lubricant described above, mutatis mutandis.

The invention will be further described with reference to the following examples.
Examples and Comparative Examples As identified in Table 1 below, Examples 1-5 are suitable diesters for use in the aforementioned engine lubricants according to the present invention.
Comparative Examples 6-11 are also identified in Table 1.
The characteristics of each example are shown in Table 2.

  The present invention provides engine lubricants, particularly engine lubricants used in 4-stroke engines.

Claims (20)

  An engine lubricant comprising at least one diester of 15% by weight or more and an additive of 20% by weight or less, wherein the at least one diester or, if more than one, the mixture is 100 ° C. Engine lubricant having a kinematic viscosity of 3.3 or lower, a viscosity index of 130 or higher, a pour point of −30 ° C. or lower and a Noack evaporation loss of 15% by mass or lower.   SAE 0W engine lubricant comprising at least one diester of 15% by weight or more and an additive of 20% by weight or less, wherein the at least one diester, or a mixture thereof, if more than one is present An engine lubricant having a kinematic viscosity of 3.3 or lower at 100 ° C., a viscosity index of 130 or higher, a pour point of −30 ° C. or lower and a Noack evaporation loss of 15% by mass or lower.   The engine lubricant according to claim 1 or 2, comprising 90% by mass or less of the at least one diester.   The engine lubricant according to any one of claims 1 to 3, consisting essentially of the at least one diester and the additive.   The engine lubricant according to any one of claims 1 to 3, comprising at least 25 mass% and at most 40 mass% of the at least one diester.   6. An engine lubricant according to any one of claims 1 to 3 and 5 comprising a lubricant component selected from API groups III, IV and V and mixtures thereof.   The engine lubricant of claim 6 consisting essentially of said at least one diester, said additive and at least one API Group V lubricant.   Said at least one diester has a kinematic viscosity of not more than 3.0 and / or a viscosity index of not less than 140 and / or a pour point of not more than −35 ° C. and / or a Noack evaporation loss of not more than 14% by weight at 100 ° C. The engine lubricant according to any one of claims 1 to 7. The at least one diester is
a) at least one C ₅ -C ₁₂ , preferably C ₆ -C ₁₀ aliphatic dicarboxylic acid or anhydride thereof and at least one primary or secondary, preferably primary C ₇ -C _12, if preferably those reaction products of aliphatic primary alcohols of C ₈ -C ₁₀ (at least one acid of the branching, the said at least one alcohol of the case is a linear And if the at least one acid is linear, then the at least one alcohol is branched), and b) at least one C _{5 to} C ₁₂ , preferably the anti of at least one polyalkylene glycol and aliphatic monocarboxylic acids C ₆ -C ₁₀ (the alkyl group is selected from C ₂ -C ₄ alkyl groups and mixtures thereof) Product (wherein said at least one polyalkylene glycol contains at least one repeating unit which is a branched methyl group, at least one said at least one acid is linear; and If the at least one polyalkylene glycol contains only linear repeating units, at least one of the at least one acid is branched),
The engine lubricant according to any one of claims 1 to 8, which is selected from the group consisting of:   When the diester is derived from dibasic acids or their anhydrides and primary alcohols, the diester is 17-36, more preferably 20-30, and even more preferably 23-26 carbons. 10. The diester of claim 9, comprising atoms or, if derived from monobasic acids and polyalkylene glycols, the diester contains from 17 to 40, more preferably from 20 to 30 carbon atoms. Engine lubricant.   The reaction product of the dicarboxylic acid and the alcohol is either a reaction product of a branched acid and a linear alcohol, or a reaction product of a linear acid and a branched alcohol, and a monocarboxylic acid and The reaction product of the polyalkylene glycol is a reaction product of a branched acid and polyethylene glycol, or a linear acid and polypropylene glycol or polybutylene glycol, preferably polypropylene glycol, or at least one ethylene glycol repeat. The engine lubricant according to claim 9 or 10, which is any one of a reaction product with a copolymer containing units.   The engine lubricant of claim 11, wherein the polyalkylene glycol has an average relative molecular mass generally in the range of 150-300, more preferably in the range of approximately 180-250.   The engine lubricant according to any one of claims 9 to 12, wherein the branched acid is branched at the beta position and / or does not contain a gem branched group.   The engine lubricant according to any one of claims 9 to 13, wherein the dicarboxylic acid comprises adipic acid, 3-methyladipic acid and sebacic acid.   The engine lubricant according to any one of claims 9 to 14, wherein the primary alcohol comprises 1-octanol, 1-decanol and mixtures thereof, 2-ethylhexanol and isononyl alcohol.   15. An engine lubricant according to any one of claims 9 to 14, wherein the polyalkylene glycol comprises polypropylene glycol, preferably polypropylene glycol having an average relative molecular mass in the range of 180 to 250.   17. The diester according to any of claims 1 to 16, wherein the diester is diisononyl adipate, di-n-octyl 3-methyladipate, di-2-ethylhexyl sebacate and PPG225n-octyl, n-decyl diester and mixtures thereof. The engine lubricant according to claim 1.   The engine lubricant according to any one of claims 1 to 17, comprising 15% by mass or less, more preferably 10% by mass or less of the additive.   Use of an engine lubricant according to any one of claims 1 to 18 in lubrication of a four-stroke engine.   21. A method for lubricating an engine, comprising lubricating a four-stroke engine with the engine lubricant according to any one of claims 1 to 20.