JP2012516384A - Ashless lubricating oil composition - Google Patents

Abstract

A lubricating oil composition having improved antioxidant capacity is provided by an additive composition comprising a metal-free sulfur-containing compound, an aromatic amine, and a hindered amine. Particularly effective metal-free sulfur-containing compounds include ashless dithiocarbamates such as methylene bis (dibutyldithiocarbamate), and sulfurized fatty acids.

Description

  The present invention relates to lubricating oil compositions that are stabilized from oxidation by the presence of (a) a metal-free sulfur-containing compound, (b) a hindered amine, and (c) an aromatic amine.

  The present invention relates to lubricating oil compositions, methods for their preparation and uses. Specifically, the present invention relates to a lubricating composition comprising an antioxidant additive comprising a metal-free sulfur-containing compound, a hindered amine, and an aromatic amine.

  Oxidation is a major cause of lubricant breakdown. This shortens the life of the lubricating oil and forces more frequent replacement, especially in harsh environments such as internal combustion engines.

  Antioxidants have therefore played an important role as an additive in lubricating oils to extend the useful life of these lubricating oils. Aryl amines (also called aromatic amines), particularly secondary diaryl amines, such as alkylated diphenylamines, phenothiazines, and alkylated N-naphthyl-N-phenylamines, were important additives to lubricating compositions. . Phenolic compounds were also important in delaying oxidation.

  Other combinations of antioxidants have also been used. US Pat. Nos. 5,073,278 and 5,273,669 to Schumacher et al. Disclose synergistic combinations of aromatic and hindered amines in lubricating oils. US Pat. No. 5,268,113 to Evans et al. Discloses a combination of a hindered amine and a phenolic compound.

  Sulfurized organic compounds have also been shown to have antioxidant activity. US Pat. No. 4,880,551 to Doe and US Pat. No. 6,743,759 to Stunkel disclose synergistic effects between ashless dithiocarbamate and triazole compounds. US Pat. No. 6,806,241 discloses a synergistic effect between an ashless dithiocarbamate, a molybten compound and an alkylated diphenylamine.

US Pat. No. 5,073,278

US Pat. No. 5,273,669

US Pat. No. 5,268,113

U.S. Pat. No. 4,880,551

U.S. Pat. No. 6,743,759

US Pat. No. 6,806,241

US Pat. No. 5,874,035

U.S. Pat.No. 4,085,104

U.S. Pat. No. 4,857,595

US Pat. No. 5,098,944

Nitrones, Nitronates and Nitroxides "E. Breuer et al., 1989, John Wiley & Sons

  Accordingly, an object of the present invention is to provide a lubricating oil composition that is stabilized from oxidation by the presence of (a) a metal-free sulfur-containing compound, (b) a hindered amine, and (c) an aromatic amine. .

The inventors have discovered that lubricating oil compositions comprising additives comprising a metal-free sulfur-containing compound, an aromatic amine, and a hindered amine synergistically provide antioxidant protection. More specifically, the present invention relates to mineral or synthetic base oils, mixtures or greases of such oils, and (as weight percent of the total lubricating oil composition)
At least one metal-free sulfur-containing compound between about 0.001 and 10%, preferably between about 0.1 and 1.0%, most preferably between about 0.25 and 0.5%;
At least one hindered amine between 0.001 and 10%, preferably between about 0.05 and 1.0%, most preferably between about 0.1 and 0.5%, and 0.001 to 10 %, Preferably between about 0.1 and 1.0%, most preferably between 0.25 and 0.5% of the antioxidant additive composition comprising at least one aromatic amine; A lubricating oil composition is provided.

  Particularly effective metal-free sulfur-containing compounds include ashless dithiocarbamates such as methylene bis (dibutyldithiocarbamate), and sulfurized fatty acids. In addition, the highest degree of synergy is, as in the preferred composition comprising about 0.1% hindered amine, about 0.4% aromatic amine, and about 0.5% metal-free sulfur-containing compound, This was observed using a relatively small amount of hindered amine in the additive.

Lubricating oil base stock Typical lubricating oil base stocks that can be used in the present invention can include both mineral and synthetic oils. Polyalphaolefins (also known as PAOS), esters, diesters, and polyol esters, or mixtures thereof are included. The base stock constitutes at least 90%, preferably at least 95% of the total lubricating oil composition.

A grease-based grease composition consists of a lubricating oil and a thickener system. Generally, the base oil and thickener system comprise 65 to 95 and 3 to 10 weight percent of the final grease, respectively. The most commonly used base oils are petroleum, bio-based oils or synthetic base oils. The most common thickener systems known in the art are neutralizing fatty carboxylic acids, typically directly in a base fluid using lithium hydroxide, or Lithium soaps and lithium complex soaps produced by saponifying acid esters. Lithium complex greases differ from simple lithium soaps by the incorporation of complexing agents, usually consisting of dicarboxylic acids.

  Other thickener systems that can be used in the present invention include aluminum, aluminum complexes, sodium, calcium, calcium complexes, organoclays, sulfonates, and polyureas.

Metal-free sulfur-containing compounds There are many types of sulfur-containing compounds used in the present invention. Typically, sulfur-containing compounds contain sulfur atoms or groups of atoms that are oil soluble and can be readily oxidized. Examples of such compounds are sulfurized olefins, alkyl sulfides and disulfides, dialkyl dithiocarbamates, dithiocarbamate esters, ashless dithiocarbamates, thiuram disulfides, sulfurized fatty acids, sulfurized fatty acid derivatives, and thiadiazole compounds.

1. Sulfurized fatty acids and derivatives Sulfurized fatty acids can be prepared by reacting unsaturated fatty acids with the aforementioned sulfur sources. Examples of unsaturated fatty acids include, but are not limited to, linoleic acid, oleic acid, arachidonic acid, linolenic acid, and myristoleic acid.

  Derivatives of sulfurized fatty acids include, but are not limited to, sulfurized fatty acid esters and sulfurized fatty acid amides.

2. Other sulfur-containing compounds Ashless dithiocarbamate, tetraalkylthiuram disulfide, and thiadiazole compounds suitable for use in the present invention include, but are not limited to, methylene bis (dialkyldithiocarbamate), ethylenebis (dialkyldithio). Carbamates), and tetraalkylthiuram disulfides, where the alkyl group preferentially has between 1 and 20 carbon atoms. Examples of preferred ashless dithiocarbamates are methylene bis (dibutyldithiocarbamate) and ethylenebis (dibutyldithiocarbamate). Examples of preferred thiuram disulfides include tetrabutyl thiuram disulfide and tetraoctyl thiuram disulfide. Examples of thiadiazole compounds include dialkyl thiadiazoles.

  It is found that sulfurized olefins do not provide a remarkable synergistic effect when used in the proposed three-component system of the present invention. Sulfurized olefins are typically derived from alpha olefins, isomerized alpha olefins, cyclic olefins, branched olefins, and polymeric olefins by reaction with a sulfur source. Specific examples of olefins include, but are not limited to, 1-butene, isobutylene, diisobutylene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and polymers having C60 and longer carbon chains. To olefins. Examples of sulfur sources include sulfur, hydrogen sulfide, sodium hydrogen sulfide, sodium sulfide, sulfur chloride, and sulfur dichloride.

Hindered amines The hindered amines used in the present invention are of many types, with three being dominant, namely pyrimidine, piperidine, and stable nitroxide compounds. Even more are the books “Nitrones, Nitronates and Nitroxides” E.I. Breuer et al., 1989, in John Wiley & Sons. Hindered amines, also known as HALS (hindered amine light stabilizers), are a special class of amines that are capable of antioxidant activity. They are widely used in the plastics industry to retard photochemical degradation.

1. Pyrimidine Compounds Pyrimidine compounds consist of substituted tetrahydro forms and are represented by the following (I), 2,3 as described by Volodarsky et al. In US Pat. No. 5,874,035 and Alink in US Pat. No. 4,085,104. , 4,5 General structure of tetrahydropyrimidine

including. R1 is H, O, or a hydrocarbon having 1 to 25 carbon atoms, or an alkoxy group having an oxygen moiety containing 1 to 25 carbon atoms with oxygen bonded to nitrogen. R2, R3, R4, R5, R6 and R7 are each hydrocarbons having 1 to 25 carbon atoms. Most preferably R2, R3, R6 and R7 are methyl.

Other pyrimidine compounds consist of hexahydro form (II),

R8 and R11 are H, O, or a hydrocarbon having 1 to 25 carbon atoms, or an alkoxy group having an oxygen moiety having 1 to 25 carbon atoms with oxygen bonded to nitrogen. . R9, R10, R11, R12, R13, R14 and R15 are each hydrocarbons having 1 to 25 carbon atoms. Most preferably R9, R10, R14 and R15 are methyl.

2. Piperidine Compounds Piperidine compounds used in the present invention are described by Schumacher et al. In US Pat. No. 5,073,278 and by Evans in US Pat. No. 5,268,113. These compounds have the general formula (III)

Where R 16 is H, O, or a hydrocarbon having 1 to 25 carbon atoms, or an oxygen moiety having 1 to 25 carbon atoms with oxygen bonded to nitrogen. It is an alkoxy group having. R17, R18, R22 and R23 are preferentially methyl groups. R20 is either OH, H, O, NH2, an ester group O2CR (where R is a hydrocarbon having 1 to 25 carbon atoms), or a succinimide group.

  Examples of hindered amines based on piperidine include the following compounds:

4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-allyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-benzyl-4-hydroxy-2,2,6 6-tetramethylpiperidine, 1- (4-tert-butylbut-2-enyl) -4hydroxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethyl Piperidine, 1-ethyl-4-salicyloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6,6-pentamethylpiperidine, 1,2, 2,6,6-pentamethylpiperidin-4-yl- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, di (1-benzyl-2,2,6,6- Tramethylpiperidin-4-yl) maleate, di (2,2,6,6-tetramethylpiperidin-4-yl) succinate, di (2,2,6,6-tetramethylpiperidin-4-yl) glutarate, Di (2,2,6,6-tetramethylpiperidin-4-yl) adipate, di (2,2,6,6-tetramethylpiperidin-4-yl) sebacate, di (1,2,2,6, 6-pentamethylpiperidin-4-yl) sebacate, di (1,2,3,6-tetramethyl-2,6-diethylpiperidin-4-yl) sebacate, di (1-allyl-2,2,6,6) 6-tetramethylpiperidin-4-yl) phthalate, 1-hydroxy-4-β-cyanoethoxy-2,2,6,6-tetramethylpiperidine, 1-acetyl-2,2,6,6-tetramethyl Piperidin-4-yl acetate, tri (2,2,6,6-tetramethylpiperidin-4-yl) trimellitate, 1-acryloyl-4-benzyloxy-2,2,6,6-tetrainethylpiperidine, di (2,2,6,6-tetramethylpiperidin-4-yl) diethyl malonate, di (1,2,2,6,6-pentamethylpiperidin-4-yl) dibutyl malonate, di (1,2 , 2,6,6-pentamethylpiperidin-4-yl) butyl (3,5-di-tert-butyl-4-hydroxybenzyl) malonate, di (1-octyloxy-2,2,6,6-tetra) Methylpiperidin-4-yl) sebacate, di (1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, hexane-1 ′, 6 -Bis (4-carbamoyloxy-1-n-butyl-2,2,6,6-tetramethylpiperidine), toluene-2 ', 4'-bis (4-carbamoyloxy-1-n-propyl-2, 2,6,6-tetramethylpiperidine), dimethyl-bis (2,2,6,6-tetramethylpiperidine-4-oxy) silane, phenyl-tris (2,2,6,6-tetramethylpiperidine-4) -Oxy) silane, tris (1-propyl-2,2,6,6-tetramethylpiperidin-4-yl) phosphate, tris (1-propyl-2,2,6,6-tetrarnetylpiperidin-4yl) ) Phosphate, phenyl [bis (1,2,2,6,6-pentamethylpiperidin-4-yl)] phosphonate, 4-hydroxy-1,2,2,6,6-pentamethylpi Lysine, 4-hydroxy-N-hydroxyethyl-2,2,6,6-tetramethylpiperidine, 4-hydroxy-N- (2-hydroxypropyl) -2,2,6,6-tetramethylpiperidine, 1- Glycidyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, dodecyl-N- (2,2,6,6, -tetramethyl-4-piperidinyl) succinate.

  Most useful in the present invention are 2,2,6,6-tetramethylpiperidine, 1,2,2,6,6-pentaalkylpiperidine, 1-oxo-2,2,6,6-tetramethylpiperidine, and 1-alkoxy-2,2,6,6-tetramethylpiperidine.

3. Polymers containing hindered amines Polymeric 2,2,6,6-tetraalkylpiperidine and 1,2,2,6,6-pentaalkylpiperidine are also prevalent and can be used in this formulation. The polymeric compounds used in the present invention are described in U.S. Pat. No. 5,073,278 by Schumacher et al., U.S. Pat. No. 5,268,113 by Evans, and U.S. Pat. No. 4,857,595 by Kazmierzak et al. There are several types of polymeric piperidine compounds that can be utilized. Commercially available examples include Tinuvin® 622 from Ciba, and Songlight® 9440 from Songwon.

4). Other hindered amines Another class of hindered amines is disclosed in US Pat. No. 5,098,944 and has the general formula (IV)

The hindered amines of the type shown in are described.

In the formula, PSP represents the general formula (V)

Represents a substituent derived from a cyclic amine represented by a structure selected from the group
Wherein R24 represents C1-C24 alkyl, C5-C20 cycloalkyl, C7-C20 aralkyl or alkaryl, C1-C24 aminoalkyl, or C6-C20 aminocycloalkyl; R25, R26, R27 and R28 are independently R25 and R26, or R27 and R28 may be cyclized to form C5-C12 cycloalkyl containing C3 and C5 atoms, respectively, of the piperazin-2-one ring; And R30 independently represent C1-C24 alkyl, and polymethylene having 4-7 carbon atoms that can be cyclized; R31 represents H, C1-C6 alkyl, and phenyl; R32 represents C1-C25 Alkyl, H, or O, or charcoal having between 1 and 25 carbon atoms Alkoxy having hydrogen chain; p represents an integer in the range of 2 to about 10.

Diarylamine The diarylamine used in the present invention is of the type Ar2NR. These are antioxidants well known in the art and there are requirements regarding solubility in lubricating compositions, but there are no limitations on the type of diarylamine used in the present invention.

  Alkylated diphenylamine is a well-known antioxidant and there are no specific limitations on the type of secondary diarylamine used in the present invention, preferably secondary diarylamine antioxidants are generally Having the formula (X), wherein R33 and R34 each independently represents a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. R35 represents either an H atom or an alkyl group containing 1 to 30 carbon atoms. Illustrative substituents for aryl include aliphatic hydrocarbon groups such as alkyl having about 1-20 carbon atoms, hydroxy, carboxyl or nitro, e.g., alkaryl having 7-20 carbon atoms in the alkyl group. The group can be mentioned. Aryl is preferably substituted or unsubstituted phenyl or naphthyl, especially where one or both of the aryl groups are substituted with alkyl such as alkyl having 4 to 18 carbon atoms. R35 can be either H or alkyl having 1 to 30 carbon atoms. The alkylated diphenylamine used in the present invention can be composed of structures other than those shown in the above formula showing only one nitrogen atom in the molecule. Thus, an alkylated diphenylamine has two aryl groups with at least one nitrogen attached to it, such as in the case of various diamines having, for example, a secondary nitrogen atom and two aryls on one of the nitrogens. Then, it can consist of different structures. The alkylated diphenylamine used in the present invention preferably has antioxidant properties in the lubricating oil, even in the absence of molybdenum compounds.

  Examples of some alkylated diphenylamines that can be used in the present invention include diphenylamine, 3-hydroxydiphenylamine, N-phenyl-1,2-phenylenediamine, N-phenyl-1,4-phenylenediamine, dibutyldiphenylamine, dioctyl Examples include diphenylamine, dinonyldiphenylamine, phenyl-α-naphthylamine, phenyl-β-naphthylamine, diheptyldiphenylamine, and p-oriented styrenated diphenylamine.

Phenothiazine Phenothiazine has the general structure (VII)

Another class of diarylamines having: wherein R36 is H or alkyl having 1 to 30 carbon atoms, and R37 and R38 are alkyl having 1 to 30 carbon atoms.

Lubricating Oil Composition The lubricating oil composition of the present invention can be prepared by adding a sulfur-containing compound, a hindered amine, and an aromatic amine to a base stock. The combination can include 0.001 to 10 weight percent of each of the three additives in the lubricating oil.

Grease Composition In another embodiment, the grease composition of the present invention can be prepared by adding a sulfur-containing compound, a hindered amine, and an aromatic amine to a base grease. The combination can include 0.001 to 10 weight percent of each of the three additives in the lubricating oil.

Other Additives In addition, other additives can be added to the lubricating composition. Examples of these additives include the following components.

  Other antioxidants including phenol, hindered phenol, hindered bisphenol, sulfurized phenol, zinc dihydrocarbyl dithiophosphate, zinc dithiocarbamate, organic phosphite. A more complete list of useful phenols can be found in US Pat. No. 5,073,278 to Schmacher et al.

  Anti-wear additives including zinc dihydrocarbyl dithiophosphate, tricresol phosphate, dilauryl phosphate.

  A dispersant comprising polymethacrylate, styrene / maleic acid ester copolymer, substituted succinamide, polyamine succinamide, polyhydroxysuccinic acid ester, substituted Mannich base, and substituted triazole.

  A detergent comprising neutral and base excess alkali and alkaline earth metal sulfonates, neutral and base excess alkali and alkaline earth metal phenates, sulfurized phenates, base excess phosphonates, and thiophosphonates.

  Viscosity index improvers including polyacrylates, polymethacrylates, vinyl pyrrolidone / methacrylate copolymers, polyvinyl pyrrolidone, polybutenes, olefin copolymers, styrene / acrylate copolymers.

  A pour point depressant comprising polymethacrylate and an alkylated naphthalene derivative.

Lubricating oil composition comprising hindered amine, diarylamine and methylene bis (dibutyldithiocarbamate) Pressure differential scanning calorimetry (PDSC) was performed according to ASTM test method D6186. These tests consisted of a lubricating oil composition comprising a polyalphaolefin oil from BP, Durasyn® 166; and a crankcase dispersant containing 1.2% Nitrogen from Infineum, Infineum® C9269. It carried out about. Also provided in the lubricating oil composition is a hindered amine having the name 4-piperidol-2,2,6,6-tetramethyl-RPW stearin (fatty acid mixture) from Cytec, Cyasorb (R) UV -3853. Metal-free sulfur-containing compounds are R.I. T.A. Vanderbilt Company, Inc. Methylenebis (dibutyldithiocarbamate) from VANLUBE® 7723. The diarylamine used is R.I. T.A. Vnaderbilt Company, Inc. A mixture of octylated and butylated diphenylamines from Vanlube® 961 additive. The test is performed by blending the ingredients and placing in a DSC cell, heating the cell to 180 ° C., and then pressurizing with 500 psi oxygen. What is measured is the oxidation induction time (OIT), which is the time required to observe the exotherm. The longer the OIT, the greater the oxidative stability of the oil blend. The results are shown in Table I, labeled “Induction Time (min)”.

Lubricating oil composition comprising hindered amine, diarylamine and sulfurized fatty acid The lubricating oil composition was prepared as Cyasorb (R) UV-3853 and Vanlube (R) 961, and a sulfur-containing compound, approximately 15% (w / W) a sulfurized fatty acid mixture containing sulfur and a combination consisting of Arkema® VPS 15 was prepared as in Example 1 above. PDSC (ASTM D1686) was performed as in Example 1. Data are reported in Table II.

(Comparative Example 3)
Lubricating oil composition comprising a hindered amine, a diarylamine, and a sulfurized olefin. A lubricating oil composition is prepared using Cyasorb UV3853 and Vanlube® 961 with R.I. T.A. Vanderbilt Company, Inc. Prepared according to Example 1 above, including a combination of sulfurized olefins containing approximately 45% sulfur from the sulfur-containing compound VANLUBE® SB. PDSC (ASTM D1686) was performed as in Example 1. Data are reported in Table III.

Claims (16)

At least 90% by weight of a lubricant base stock, and (a) between about 0.001 and 10% metal free selected from the group consisting of sulfurized fatty acids, ashless dithiocarbamates, tetraalkylthiuram disulfides, and thiadiazoles Sulfur-containing compounds,
A lubricating composition comprising an antioxidant additive composition comprising (b) about 0.001 to 10% hindered amine and (c) about 0.001 to 10% diarylamine. The additive composition is
(A) between about 0.1 and 1.0% of a metal-free sulfur-containing compound;
The lubricating oil composition of claim 1, comprising (b) between about 0.05 and 1.0% hindered amine, and (c) between about 0.1 and 1.0% diarylamine. The additive composition is
(A) between about 0.25 and 0.5% of a metal-free sulfur-containing compound;
The lubricating oil composition of claim 2, comprising (b) between about 0.1 and 0.5% hindered amine, and (c) between about 0.25 and 0.5% diarylamine. The additive composition is
(A) about 0.5% metal-free sulfur-containing compound;
4. The lubricating oil composition of claim 3, comprising (b) about 0.1% hindered amine and (c) about 0.4% diarylamine.   The lubricating oil composition according to claim 1, wherein the metal-free sulfur-containing compound is selected from the group consisting of ashless dithiocarbamates and sulfurized fatty acids.   The lubricating oil composition according to claim 5, wherein the ashless dithiocarbamate is methylenebis (dibutyldithiocarbamate) or sulfurized fatty acid.   The lubricating oil composition according to claim 1, wherein the sulfur-containing compound is methylene bis (dibutyldithiocarbamate) and the hindered amine is 4-piperidol-2,2,6,6-tetramethyl-RPW stearin (fatty acid mixture).   The lubricating oil composition according to claim 2, wherein the sulfur-containing compound is methylene bis (dibutyldithiocarbamate).   The lubricating oil composition according to claim 3, wherein the sulfur-containing compound is methylene bis (dibutyldithiocarbamate).   The lubricating oil composition according to claim 4, wherein the sulfur-containing compound is methylene bis (dibutyldithiocarbamate). The additive composition is
(A) about 0.5% methylenebis (dibutyldithiocarbamate),
2. (b) comprising about 0.1% 4-piperidol-2,2,6,6-tetramethyl-RPW stearin (fatty acid mixture), and (c) about 0.4% diarylamine. The lubricating oil composition described.   The lubricating oil composition according to claim 1, wherein the sulfur-containing compound is a sulfurized fatty acid.   The lubricating oil composition according to claim 1, wherein the sulfur-containing compound is a sulfurized fatty acid and the hindered amine is 4-piperidol-2,2,6,6-tetramethyl-RPW stearin (fatty acid mixture).   The lubricating oil composition according to claim 2, wherein the sulfur-containing compound is a sulfurized fatty acid.   The lubricating oil composition according to claim 3, wherein the sulfur-containing compound is a sulfurized fatty acid. The additive composition is
(A) about 0.5% sulfurized fatty acid,
2. (b) comprising about 0.1% 4-piperidol-2,2,6,6-tetramethyl-RPW stearin (fatty acid mixture), and (c) about 0.4% diarylamine. The lubricating oil composition described.