JP2008274276A - Lubricating oil composition containing hydrated alkali metal borate with improved frictional characteristic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricating oil composition with improved frictional and wear performance. <P>SOLUTION: The lubricating oil composition, improved in frictional and wear performance especially when the ratio of polysulfide is controlled, comprises a major amount of an oil of lubricating viscosity; at least one alkali metal borate; at least one dihydrocarbyl polysulfide component comprising a mixture of sulfides and having at least 30% dihydrocarbyl tetrasulfide or higher sulfides; at least one non-acidic phosphorous component comprising a trihydrocarbyl phosphite; at least one dihydrocarbyl dithiophosphate; and a phosphorous component comprising a dihydrocarbyl phosphite component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates generally to lubricants, and more particularly to automotive gear lubricants.

  It is well known to use dispersed alkali metal borates in lubricating oil formulations. Various patent documents teach combinations of alkali metal borates with sulfur compounds and certain phosphorus compounds. For example, see Patent Documents 1 and 2 and the patent documents cited therein. These prior formulations have the problem of short shelf life compared to other commercial lubricants that do not use borate solid dispersions. U.S. Pat. No. 6,057,059 teaches whether this drawback can be overcome by careful use of non-acidic phosphorus compounds. Patent Document 3 also teaches whether the load bearing capacity can be maintained or improved by considering the balance of the ratio of tetrasulfide: trisulfide: disulfide in the lubricating oil composition.

U.S. Pat. No. 4,717,490 U.S. Pat. No. 4,472,288 US Patent Application Publication No. US2006 / 0252656, filed May 4, 2005

  The present invention relates to a gear oil additive package, a lubricating oil composition, a method for manufacturing a gear oil additive package, and a method for manufacturing a lubricating oil composition.

The present invention provides a lubricating oil composition comprising an oil of lubricating viscosity in which a mixture of the following components is dispersed (usually dispersed in small amounts): (a) a hydrated alkali metal borate component; (B) less than about 64.5% by weight dihydrocarbon trisulfide, more than about 5.5% by weight dihydrocarbon disulfide, and at least about 30.0% by weight dihydrocarbon tetrasulfide or more; A dihydrocarbon polysulfide component composed of a mixture containing polysulfide, (c) a trihydrocarbon phosphite component, and at least 90% by mass of the component is represented by the formula: (RO) ₃ P (where R is the number of carbon atoms) A non-acidic phosphorus component having 4 to 24 hydrocarbon groups), and (d) a dihydrocarbon dithiophosphate derivative. In addition, optionally, it is a dihydrocarbon phosphite hydrogen ester component, of which at least 90% by mass is represented by the formula: (RO) ₂ POH (where R is a hydrocarbon group having 4 to 24 carbon atoms) A phosphite component having can also be used in the lubricating oil composition.

  By adjusting the ratio of polysulfide according to the present invention, it is possible to achieve optimum friction performance while maintaining improvement in wear resistance performance.

  The present invention relates to a gear oil additive package, a lubricating oil composition, a method for manufacturing a gear oil additive package, and a method for manufacturing a lubricating oil composition.

[Additive Package]
The gear oil additive package of the present invention is an oil-soluble additive composition. The gear oil additive package can be used for gear lubricants. The additive package of the present invention comprises (1) at least one hydrated alkali metal borate component, (2) less than about 64.5% by weight dihydrocarbon trisulfide, and more than about 5.5% by weight two. At least one dihydrocarbon polysulfide component comprising a mixture comprising hydrocarbon disulfide and at least about 30.0% by weight of dihydrocarbon tetrasulfide or higher polysulfide; (3) a trihydrocarbon phosphite component And at least 90% by weight of at least one non-acidic phosphorus component having the formula: (RO) ₃ P (where R is a hydrocarbon group having 4 to 24 carbon atoms), and (4) At least one dihydrocarbon dithiophosphate. “Non-acidic” refers to phosphorus contained in the component and is not intended to limit the acidic or non-acidic hydrocarbon groups attached to the phosphorus. This base mixture is combined with a base oil, dialkyl phosphite, antifoam, viscosity modifier, metal deactivator, and optionally a detergent, dispersant and antioxidant to fully lubricate. Product can be prepared.

[Hydrated alkali metal borate]
The first additive component used in the lubricating oil composition of the present invention is a particulate hydrated alkali metal borate. Granular hydrated alkali metal borates are well known in the art and are also commercially available. Representative patent documents disclosing suitable borates and production methods include the following: U.S. Pat. Nos. 3,133,727, 3,919,521, 3,857,772, 3,907,601, 3,997,454, 4,089,790. No. and No. 6534450.

The hydrated alkali metal borate can be represented by the following formula.

M ₂ O · mB ₂ O ₃ · nH ₂ O

[Wherein M is an alkali metal having an atomic number in the range of 11 to 19, such as sodium or potassium, and m is a number from 2.5 to 4.5 (which may be an integer or a fraction), N is a number from 1.0 to 4.8. Preferred is hydrated potassium borate, especially hydrated potassium triborate microparticles having a potassium to boron ratio of about 1: 2.75 to 1: 3.25. The average particle size of the hydrated borate particles is generally less than 1 micron. ]

[Dihydrocarbon polysulfide]
The dihydrocarbon polysulfide component used in the present invention is less than about 64.5% by weight, preferably no more than about 60.0% by weight dihydrocarbon trisulfide, more than about 5.5% by weight, preferably about 6. It comprises a mixture comprising greater than 0% by weight of dihydrocarbon disulfide and at least about 30.0% by weight, preferably at least 40% by weight of dihydrocarbon tetrasulfide or higher polysulfide. The dihydrocarbon polysulfide mixture preferably contains mainly dihydrocarbon tetrasulfide or higher polysulfide. “Polysulfide” as used herein may include small amounts of dihydrocarbon monosulfide, also referred to as monosulfide or sulfide. In general, monosulfide is present in relatively small amounts of less than about 1% by weight of the total sulfur-containing compound present. Usually monosulfide is present in an amount ranging from about 0.3% to about 0.4% by weight. Preferably the monosulfide is less than about 0.4 wt%, more preferably less than about 0.3 wt%.

  “Hydrocarbon groups” include hydrocarbon groups as well as substantially hydrocarbon groups. “Substantially hydrocarbon” refers to a group containing a heteroatom substituent that does not substantially alter the main hydrocarbon character of the substituent. Non-limiting examples of hydrocarbon groups include: (1) Hydrocarbon substituents, ie, aliphatic (eg, alkyl or alkenyl) and alicyclic (eg, cycloalkyl, cycloalkenyl, etc.) substituents , Aromatic, aliphatic and alicyclic substituted aromatic substituents, as well as cyclic substituents in which the ring is terminated by another part of the molecule (ie, any two substituents indicated together, for example (2) substituted hydrocarbon substituents, ie non-hydrocarbon groups that do not substantially change the main hydrocarbon properties of the substituent, such as halo (particularly Is a substituent such as chloro and fluoro), hydroxy, mercapto, nitro, nitroso and sulfoxy, including non-hydrocarbon groups, (3) heteroatom substituents, Otherwise substituent containing atoms other than carbon in a ring or in the chain composed of carbon atoms (e.g., alkoxy or alkylthio). Suitable heteroatoms include, for example, sulfur, oxygen, nitrogen, and substituents containing one or more heteroatoms, as exemplified by pyridyl, furyl, thienyl and imidazolyl.

  In general, there are no more than about 2 and preferably no more than 1 heteroatom substituent for every 10 carbon atoms in a hydrocarbon group. Usually there are no heteroatom substituents in the hydrocarbon group, in which case the hydrocarbon group is a hydrocarbon. Preferred is an alkyl group, more preferably the hydrocarbon group is tertiary butyl.

  Organic polysulfides can be prepared as described in US Pat. Nos. 6,489,721, 6,642,187 and 6,689,723, which are also incorporated herein by reference.

[Non-acidic phosphorus compounds]
At least two types of non-acidic phosphorus components are also used in the lubricating oil composition of the present invention. At least two non-acidic phosphorus components are, according to the invention, non-acidic as defined above, more preferably two phosphorus compounds, a trihydrocarbon phosphite and a phosphoric acid derivative, i.e. two It consists of hydrocarbon dithiophosphate.

  An acidic phosphorus compound, as used herein, means a hydrogen atom bonded directly to a phosphorus atom, or a compound containing a hydrogen atom bonded to the heteroatom, wherein a heteroatom is bonded to the phosphorus atom. Non-acidic phosphorus compounds, as used herein, are trihydrocarbyl phosphite or dithiophosphate derivatives that may contain acid groups such as carboxylic acid groups, but hydrogen atoms bonded directly to phosphorus atoms. Alternatively, it means that a hetero atom is bonded to a phosphorus atom and a hydrogen atom bonded to the hetero atom is not included. Thus, compounds with —P—H, —P—O—H, or —P—S—H are considered acidic, while dithiophosphates such as those described in US Pat. No. 5,922,657 are As used herein, even if it has a carboxylic acid functionality, it will be considered non-acidic.

  The acidic phosphoric acid compound can be based on a phosphorus compound as described in US Pat. No. 4,575,431 (Salentine), the disclosure of which is also incorporated herein by reference. If an amino phosphorus compound is used, the amino phosphorus compound is preferably a dithiophosphate amine (ie, an amine salt of a dithiophosphate). Representative dithiophosphates that can be used in the lubricants of the present invention are well known in the art. These dithiophosphates contain two hydrocarbon groups and one hydrogen functional group and are therefore acidic and must be neutralized for use in the compositions of the present invention. The hydrocarbon group that can be used in the present invention is preferably an aliphatic alkyl group having 3 to 8 carbon atoms.

  Representative dihydrocarbon dithiophosphates include di-2-ethyl-1-hexyl dithiophosphate hydrogen ester, diisooctyl dithiophosphate hydrogen ester, dipropyl dithiophosphate hydrogen ester, and di-4-methyl-2- Mention may be made of pentyldithiophosphate hydrogen ester.

  Preferred dithiophosphates are dihexyl dithiophosphate hydrogen ester, dibutyl dithiophosphate hydrogen ester, and di-n-hexyl dithiophosphate hydrogen ester.

  For use in the present invention, the acidic phosphate ester is completely neutralized by reaction with an alkylamine, as disclosed in US Pat. No. 4,575,431 (Salentine). Neutralization must be at least 80% complete. For best results, neutralization should be in the range of 85% to 100%, where 100% neutralization means the reaction of each acidic hydrogen atom with one alkylamine.

  The amine moiety is generally derived from an alkylamine. The amine alkyl group has a length of 10 to 30 carbon atoms, preferably 12 to 18 carbon atoms. Typical amines include pentadecylamine, octadecylamine, cetylamine and the like. Most preferred is oleylamine. When using a mixture of dithiophosphate and sulfur-free phosphate, the molar ratio of dithiophosphate to sulfur-free phosphate should be in the range of 70:30 to 30:70, preferably 55:45 to 45:55, most preferably 1: 1. The molar ratio of substituted dihydrogen phosphate to disubstituted hydrogen phosphate should be in the range 30:70 to 55:45, preferably 35:65 to 50:50, most preferably 45:55. It is.

  Preferred non-acidic phosphoric acid derivatives are dithiophosphates as described in US Pat. No. 5,992,657 (Kamenzin, et al.). The dihydrocarbon ester group is preferably an alkyl such as that represented by Irgalube 353 from Ciba Specialty Chemicals.

In addition, examples of the phosphorus compound of the present invention include non-acidic trihydrocarbon phosphites. The trihydrocarbon phosphites that can be used in the present invention include (RO) ₃ P (where R is about 4 to 24 carbon atoms, more preferably about 8 to 18 carbon atoms, most preferably carbon atoms). A hydrocarbon group of about several to about 14). The hydrocarbon group may be saturated or unsaturated. The hydrocarbon group is preferably alkyl. More preferably, the trialkyl phosphite contains at least 90% by weight of the structure: (RO) ₃ P, where R is as defined above. Representative trialkyl phosphites include, but are not limited to, tributyl phosphite, trihexyl phosphite, trioctyl phosphite, tridecyl phosphite, trilauryl phosphite Mention may be made of esters, and trioleyl phosphites. A particularly preferred trialkyl phosphite is trilauryl phosphite, such as the commercially available Duraphos TLP from Rhodia Incorporated Phosphorus and Performance Derivatives. And Doverphos 53 manufactured by Dover Chemical Corporation. Such trialkyl phosphites may contain small amounts of dialkyl phosphites as impurities, in some cases as much as 5% by weight. Preference is given to mixtures of phosphites containing hydrocarbon groups of about 10 to 20 carbon atoms. These mixtures are usually derived from animal or natural plant materials. Typical hydrocarbon group mixtures are commonly known as palm, beef tallow, tall oil and soybean oil.

Optionally, in addition to the trihydrocarbon phosphite, a dihydrocarbon phosphite can be added to the composition of the present invention. Dihydrocarbon phosphites that can be used in the present invention include (RO) ₂ POH, where R is as previously defined. Particularly preferred dihydrocarbon phosphites are dialkyl phosphites. More preferably, the dialkyl phosphite is dioleyl hydrogen phosphite, such as Duraphos AP-240L available from Rhodia, Inc., Phosphorus and Performance Derivatives, which is commercially available. Such dialkyl phosphites may contain small amounts of impurities, in some cases as high as 6% by weight. Preference is given to mixtures of phosphites containing hydrocarbon groups of about 10 to 20 carbon atoms.

[Polyalkylene co-oligomer]
Optionally, polyalkylene co-oligomers can be used in the present invention. A preferred polyalkylene co-oligomer is a co-oligomer of ethylene and an olefin having no polar group. Particularly preferred polyalkylenes are the Lucant ™ series of synthetic oils sold by Mitsui Chemicals (USA) Incorporated, New York, NY, or ExxonMobil Chemical Company SpectraSyn Ultra ™ series of synthetic oils sold by (ExxonMobil Chemical Company). Typical oils in these series have a kinematic viscosity (ASTM D445, 100 ° C.) of 10 to 2000 cSt. Preferred oils are those with a viscosity between 100 and 2000 cSt.

[Lubricating oil composition]
Hydrated alkali metal borates, dihydrocarbon polysulfides, and non-acidic phosphorus components are generally based on the ability to sufficiently lubricate gears and other components in automotive axles and transmissions and stationary industrial gear drives. Added to the oil. Generally, the lubricating oil composition of the present invention contains a major amount of oil of lubricating viscosity and a minor amount of gear oil additive package.

  One aspect of the present invention provides a combination of (1) sodium triborate, (2) tertiary butyl polysulfide, (3) trilauryl phosphite, and (4) dialkyldithiophosphate, with a major amount of lubrication. It is contained in oil of viscosity. Optionally, a polyalkylene co-oligomer is also added to the lubricating oil composition.

The base oil used may be any oil of various lubricating viscosities. The base oil of lubricating viscosity used in such a composition may be a mineral oil or a synthetic oil. Base oils with a viscosity of at least 40 ° C. and 2.5 cSt and a pour point of less than 20 ° C., preferably 0 ° C. or less, are desirable. Base oils can be derived from synthetic or natural sources. Examples of the mineral oil used as the base oil in the present invention include paraffinic, naphthenic and other oils that are usually used in lubricating oil compositions. Synthetic oils can include, for example, both hydrocarbon synthetic oils and synthetic esters having a desired viscosity and mixtures thereof. Examples of the hydrocarbon synthetic oil include oil synthesized by polymerization of ethylene, polyalphaolefin or PAO oil, or oil synthesized by a hydrocarbon synthesis method using carbon monoxide gas and hydrogen gas as in the Fischer-Tropsch process. (That is, Fischer-Tropsch oil). Examples of Fischer-Tropsch oil that can be used in the present invention include, but are not limited to, U.S. Patent Application Publication Nos. US 2006/0289337, US 2006/0276355, US 2004/0079078, and US Pat. No. 6,080,301. Nos. 6090989 and 6165949, which are also described in this specification as reference contents. Other Fischer-Tropsch oils that can be used in the method of the present invention include oils such as those described in pending US patent application Ser. Nos. 11 / 613,83 and 11 / 400,570, These are also described in this specification as reference contents. Synthetic hydrocarbon oils that can be used include alpha olefin liquid polymers having the proper viscosity. Particularly useful are hydrogenated liquid oligomers of C ₆ -C ₁₂ alpha olefins such as 1-decene trimer. Similarly, alkylbenzenes of the proper viscosity, such as didodecylbenzene, can be used. Synthetic esters that can be used include esters of monocarboxylic acids and polycarboxylic acids with monohydroxyalkanols and polyols. Representative examples include didodecyl adipate, pentaerythritol tetracaproate, di-2-ethylhexyl adipate, and dilauryl sebacate. Complex esters synthesized from mixtures of mono and dicarboxylic acids and mono and dihydroxy alkanols can also be used. A blend of mineral and synthetic oils can also be used.

  Thus, the base oil may be a refined paraffinic base oil, a refined naphthenic base oil, or a synthetic or non-hydrocarbon oil of lubricating viscosity. The base oil may be a mixture of mineral oil and synthetic oil.

  In addition, other additives well known in lubricating oil compositions can be added to the additive composition of the present invention to finish the formulated oil.

  The hydrated alkali metal borate component generally comprises 0.1 to 20.0% by weight of the lubricating oil composition, preferably 0.5 to 15.0% by weight, more preferably 1.0 to 9.0. Occupies mass%. The dihydrocarbon polysulfide component accounts for 0.1 to 10.0% by weight of the lubricating oil composition, preferably 0.2 to 4.0% by weight, more preferably 0.25 to 3.0% by weight. . The trihydrocarbon phosphite component comprises 0.01 to 15.0% by weight of the lubricating oil composition, preferably 0.05 to 5.0% by weight, more preferably 0.20 to 1.5% by weight. %. The dihydrocarbon dithiophosphate component comprises 0.03 to 3.0% by weight of the lubricating oil composition, preferably 0.07 to 1.5% by weight, more preferably 0.15 to 0.9% by weight. Occupy. When the dihydrocarbon phosphite is optionally added to the lubricating oil composition, it generally accounts for 0.01 to 10.0% by weight, preferably 0.05 to 5.0% by weight of the lubricating oil composition. More preferably 0.1 to 1.0% by mass.

  Optionally, polyalkylene co-oligomers may be used in the lubricating oil composition. The lubricating oil composition preferably contains about 0.1 to 10% by mass of the polyalkylene derivative. More preferably, the lubricating oil composition contains about 1 to 7 weight percent polyalkylene derivative. Most preferably, the lubricating oil composition contains about 2-5% by weight of the polyalkylene derivative.

  The lubricating oil composition described above can be produced by adding an additive package to the lubricating base oil. Generally, the lubricating oil composition contains 1.0 to 50.0% by weight of the additive package, preferably the lubricating oil composition contains 1 to 10.0% by weight of the additive package, and more preferably the lubricating oil. The composition contains 3.0 to 8.0 weight percent additive package.

[Other additives]
Various other additives may be present in the lubricating oil of the present invention. These additives include antioxidants, viscosity index improvers, dispersants, rust inhibitors, antifoam agents, corrosion inhibitors, other anti-wear additives, demulsifiers, friction modifiers, pour point depressants. , And other various known additives. Preferred dispersants include known succinimides and ethoxylated alkylphenols and alcohols. Particularly preferred additional additives are oil-soluble succinimides, oil-soluble alkali or alkaline earth metal sulfonates, and dihydrocarbon phosphites.

  The following additive components are some examples of components that can be preferably used in the present invention. Examples of these additives are given to illustrate the invention, but are not intended to limit the invention.

1) Metal detergents Sulfurized or unsulfurized alkyl or alkenyl phenates, alkyl or alkenyl aromatic sulfonates, borated sulfonates, sulfurized or unsulfurized metal salts of polyhydroxyalkyl or alkenyl aromatic compounds, alkyl or alkenyl hydroxy aromatic sulfonates, Sulfurized or unsulfurized alkyl or alkenyl naphthenates, metal salts of alkanolic acids, metal salts of alkyl or alkenyl polyacids, and chemical and physical mixtures thereof.

2) Antioxidants Antioxidants reduce the tendency of mineral oil to degrade during service, and oxidation products such as metal surface sludge and varnish deposits and increased viscosity are evidence of degradation. . Examples of antioxidants that can be used in the present invention include, but are not limited to, phenolic (phenolic) antioxidants such as 4,4′-methylene-bis (2,6-di-tert). -Butylphenol), 4,4'-bis (2,6-di-tert-butylphenol), 4,4'-bis (2-methyl-6-tert-butylphenol), 2,2'-methylene-bis (4 -Methyl-6-tert-butylphenol), 4,4'-butylidene-bis (3-methyl-6-tert-butylphenol), 4,4'-isopropylidene-bis (2,6-di-tert-butylphenol) 2,2′-methylene-bis (4-methyl-6-nonylphenol), 2,2′-isobutylidene-bis (4,6-dimethylphenol), 2,2′-5-methylene Bis (4-methyl-6-cyclohexylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6 tert-butylphenol, 2,6-di-tert-1-dimethylamino-p-cresol, 2,6-di-tert-4- (N, N′-dimethylaminomethylphenol), 4,4′-thiobis ( 2-methyl-6-tert-butylphenol), 2,2′-thiobis (4-methyl-6-tert-butylphenol), bis (3-methyl-4-hydroxy-5-tert-10-butylbenzyl) -sulfide And bis (3,5-di-tert-butyl-4-hydroxybenzyl). Diphenylamine-type antioxidants include, but are not limited to, alkylated diphenylamine, phenyl-alpha-naphthylamine, and alkylated-alpha-naphthylamine. Other types of antioxidants include metal dithiocarbamates (eg, zinc dithiocarbamate), and 15-methylenebis (dibutyldithiocarbamate).

3) Abrasion resistant additives As the name implies, these additives reduce the wear of moving metal parts. Examples of such additives include, but are not limited to, phosphate esters, carbamates, esters, and molybdenum complexes.

4) Rust prevention additive (rust prevention agent)
a) Nonionic polyoxyethylene surfactant: polyoxyethylene lauryl ether, polyoxyethylene higher alcohol ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene octyl stearyl ether, polyoxyethylene oleyl Ethers, polyoxyethylene sorbitol monostearate, polyoxyethylene sorbitol monooleate, and polyethylene glycol monooleate.
b) Other compounds: stearic acid and other fatty acids, dicarboxylic acids, metal soaps, fatty acid amine salts, metal salts of heavy sulfonic acids, partial carboxylic acid esters of polyhydric alcohols, and phosphate esters.

5) Demulsifiers Adducts of alkylphenols and ethylene oxide, polyoxyethylene alkyl ethers, and polyoxyethylene sorbitan esters.

6) Extreme pressure antiwear agent (EP / AW agent)
Zinc dialkyl-1-dithiophosphate (primary alkyl, secondary alkyl and aryl type), diphenyl sulfide, methyltrichlorostearate, chlorinated naphthalene, fluoroalkylpolysiloxane, lead naphthenate, neutralized phosphate ester, dithiophosphorus Acid esters, and sulfur-free phosphate esters.

7) Friction modifiers: fatty alcohols, fatty acids, amines, borated esters, other esters, phosphate esters, phosphite esters, and phosphonate esters.

8) Multifunctional additive Sulfurized oxymolybdenum dithiocarbamate, sulfurized oxymolybdenum organoline dithioate, oxymolybdenum monoglyceride, oxymolybdenum diethylate amide, amine-molybdenum complex compound, and sulfur-containing molybdenum complex compound.

9) Viscosity index improver Polymethacrylate type polymer, ethylene-propylene copolymer, styrene-isoprene copolymer, hydrated styrene-isoprene copolymer, polyisobutylene, and dispersion type viscosity index improver.

10) Pour point depressant polymethyl methacrylate.

11) Antifoaming agent Alkyl methacrylate polymer and dimethyl silicone polymer.

12) Metal deactivators disalicylidenepropylenediamine, triazole derivatives, mercaptobenzothiazole, and mercaptobenzimidazole.

13) Dispersants Alkenyl succinimides, alkenyl succinimides modified with other organic compounds, alkenyl succinimides modified by post-treatment with ethylene carbonate or boric acid, pentaerythritol, phenate-salicylate and their post-treatment analogues Alkali metal or mixed alkali metals, alkaline earth metal borates, hydrated alkali metal borate dispersions, alkaline earth metal borate dispersions, and polyamide ashless dispersants, or the like Mixture of dispersants.

  The following examples illustrate the invention and are not intended to limit the invention in any way other than what is contained in the appended claims.

[Examples of automotive gear oil]
The additive concentrate package shown in Table 1 can be blended by any conventional method. A typical viscosity (8.0-18.0 cSt at 100 ° C.) grade automotive gear lubricant is blended with at least one base oil shown in Table 2 by any conventional method to obtain the desired viscosity range. Can reach. A mixture of specific polysulfides is selected in accordance with the present invention to achieve the desired ratio of di, tri, tetra and higher polysulfides. Using a mixture of commercially available polysulfides (eg, TBPS344, TBPS34, TBPS454 and dialkyl disulfide from Chevron Phillips Chemical Company), the ratio (ie, relative concentration) of polysulfide is adjusted according to the present invention. Thus, the optimum friction performance can be achieved while maintaining the improvement of the wear resistance performance.

Table 2: Typical gear lubricant blends
────────────────────
Ingredient Mass%
────────────────────
Mineral oil or synthetic base oil 80-77
Viscosity index improver 9
Packages in Table 1 6-9
Friction modifier 4
Pour point depressant 1
────────────────────
Total mass% 100.00
────────────────────

  Although the friction characteristics of the lubricating oil can be improved by adding a friction modifier, the degree of improvement is limited. If an excessive amount of friction modifier is added, harmful side effects such as reduction in oxidation stability may be caused. Table 3 shows the effect on oxidation performance of adding excessive friction modifier. Oxidation performance is measured by heating the lubricant for the specified amount of time and measuring the percent increase in viscosity according to the CEC L-48-A-95 standard method. The lower the percent viscosity increase, the better.

Table 3 ──────────────────────────────────
Lubricating oil using Example 1
Limit Friction modifier Friction modifier
None 0.5%
──────────────────────────────────
Oxidation test,
CEC L-48-A-95
(160 ° C / 192 hours) Maximum increase in viscosity (100 ° C) 50% 45 95
──────────────────────────────────

  Frictional performance is very important in both manual and automatic transmission gearshifts. If the friction is too small, excessive pressure must be applied to the friction plate to effect gear synchronization prior to shifting. If the friction is too large, the friction plate does not leave smoothly after the shift is completed, and the smooth operation of the transmission cannot be obtained.

  Friction can be measured by measuring the amount of torque required to pull away the transmission friction plate after the gear shift. That is, this type of torque is called the pull-off torque and is measured as a Newton meter force.

  Specifically, the separation torque is measured by using an electric engine and a gear cone that is driven at a low rotational speed by gear reduction. A pneumatic cylinder containing controlled compressed air presses the synchronized collar against a gear cone with some axial force. During that time, torque is measured. This method allows the measurement of static and dynamic friction coefficients. After releasing the applied force, the torque for pulling the closed synchronization frame is determined, also known as the pulling torque.

  With any new gear set, there is usually an initial break-in period of about 25 gear shift cycles before a smooth shift occurs and the average pull-off torque can be measured. The ideal pull-off torque after 25 cycles (new) is less than 10 Nm. In addition to the desired average separation torque value over 100 shift cycles being approximately 2.0 Nm, it is also important that the separation torque after the break-in period is relatively constant. This can be evaluated by examining the slope of the pull-off torque curve over time. It is desirable that the curve is flat and the slope is approximately zero. If the slope is negative, the pull-off torque will gradually decrease. If the slope is positive, the pull-off torque will increase. Either situation is unacceptable because the driver feels different about the car transmission.

  In an embodiment of the present invention, it is clear how a lubricating oil composition that meets the above-mentioned friction requirements and produces optimum wear resistance performance can be achieved by an appropriate balance of the components of the lubricating oil additive package. To do. Table 4 shows the average pull-off torque after acclimation for the lubricating oil produced as shown in Table 2 using the lubricating oil additive package shown in Table 1.

  Oil 1 is manufactured using the additive package of Example 1 and comprises polysulfide, dialkyldithiophosphate, and trialkylphosphorous acid containing the specified proportions of alkali metal borates, tetra, tri and disulfide Contains ester. This particular combination of ingredients meets all friction requirements and requires a minimum amount of special friction modifiers to achieve the desired final friction properties. Oil 2 was made using the additive package of Example 2 and is a similar blend but lacking the trialkyl phosphite and dialkyl dithiophosphate components. The resulting oil has an unacceptably low draw torque. Oil 3 is manufactured using the additive package of Example 3 and lacks polysulfide, an important component of the present invention. Not only is the pulling torque very low, but the torque continues to change, leading to a negative slope, which is unacceptable. Oil 4 is manufactured using the additive package of Example 4, except that the polysulfide of Oil 4 is not composed of the desired proportions of tetra, tri and disulfide as specified in the claims. Has all the basic components of oil 1. This leads to an unacceptably high pull-off torque.

  The above effect can be seen more clearly in FIGS. 1-5, which shows the actual pull-off torque measured for each cycle for oils 1-5. It is easy to see the change in pull-off torque leading to an undesirable negative slope. FIG. 1 is a graph showing the separation torque that is flat and acceptable. FIG. 2 is a graph showing that the gradient is negative and the separation torque is gradually increased away from the allowable range. FIG. 3 is a graph showing that the gradient is flat but the pull-off torque is too low. FIG. 4 is a graph showing an undesirable negative slope where the pull-off torque does not fully reach the desired torque of 2.0 Nm. FIG. 5 is a graph showing a typical commercial oil that also has a negative slope.

  While friction performance is important for a smooth shift in the transmission, the lubricant must also have acceptable wear resistance to protect the gears. Preferred lubricating oils described in the present invention also exhibit improved wear resistance performance. Table 5 shows this. Using the FZG narrow gear stage test A10 / 16, 6R / 120, it is possible to evaluate the wear resistance performance by measuring changes in the appearance of teeth when a gradually large load (stage) is applied to the gear. Therefore, the higher the load stage, the better the performance. In Table 5, oil 1 produced from additive package 1 using trialkyl phosphite and polysulfide with the optimal ratio of tetra, tri and disulfide lacks the essential components of the present invention. It shows improved wear resistance performance compared to other oils.

Table 5 ──────────────────────────────────
Oil 1 Oil 2 Oil 3 Oil 4 Commercial oil ───────────────────────────────────
FZG acceptance stage 10 9 9 8 9
──────────────────────────────────

  The additive concentrates listed in Table 1 were used in the examples of the present invention to produce automotive gear oils, but can be used to produce industrial oils and greases as well.

[Examples of industrial oil]
Using the lubricating oil additive concentrates described in Examples 1-4 of Table 1, industrial gear oils were blended as shown in Table 6 by any conventional method to produce any desired ISO viscosity. Can reach the range.

Table 6: Industrial gear lubricant blends
────────────────────
Ingredient Mass%
────────────────────
Mineral oil or synthetic base oil 97
Package in Table 1 2.75
Demulsifier 0.25
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  Numerous variations on the present invention are possible in light of the teachings and supporting examples described herein. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described or illustrated herein.

FIGS. 1-5 are graphs of the separation torque versus gear shift cycle for the compositions of the present invention and comparative lubricating oil compositions, where FIG. 1 is a flat gradient and acceptable separation torque. It is a graph which shows. FIG. 2 is a graph showing that the gradient is negative and the separation torque is gradually increased away from the allowable range. FIG. 3 is a graph showing that the gradient is flat but the pull-off torque is too low. FIG. 4 is a graph showing an undesirable negative slope where the pull-off torque does not fully reach the desired torque of 2.0 Nm. FIG. 5 is a graph showing a typical commercial oil that also has a negative slope.

Claims (18)

A lubricating oil composition comprising an oil of lubricating viscosity in which a mixture of the following components is dispersed:
(A) at least one hydrated alkali metal borate component,
(B) less than about 64.5% by weight dihydrocarbon trisulfide, more than about 5.5% by weight dihydrocarbon disulfide, and at least about 30.0% by weight dihydrocarbon tetrasulfide or more; At least one dihydrocarbon polysulfide component comprising a mixture comprising polysulfide,
(C) comprising a trihydrocarbyl phosphite component and at least 90% by weight of which has the formula: (RO) ₃ P, wherein R is a hydrocarbon group having 4 to 24 carbon atoms, One non-acidic phosphorus component, and (d) at least one dihydrocarbon dithiophosphate. The lubricating oil composition also includes a dihydrocarbon hydrogen phosphite, and at least 90% by weight of the composition is (RO) ₂ POH, wherein R is a hydrocarbon group having 4 to 24 carbon atoms, A composition according to claim 1 having The composition of claim 1, wherein the lubricating oil composition comprises:
(A) 0.1 to 20.0% by weight of an alkali metal borate,
(B) 0.1 to 10.0% by weight of a dihydrocarbon polysulfide component,
(C) 0.01 to 15.0% by mass of a non-acidic phosphorus component, and (d) 0.03 to 3.0% by mass of a dihydrocarbon dithiophosphate.   The composition of claim 1 wherein the alkali metal borate is potassium or sodium triborate. The composition of claim 1 wherein the trihydrocarbyl phosphite is a mixture of C ₁₀ -C ₂₀ trialkyl phosphite.   The composition of claim 1 wherein the dihydrocarbon dithiophosphate is an amine salt of a dithiophosphate. Gear oil additive package containing a mixture of the following ingredients:
(A) a hydrated alkali metal borate component,
(B) less than about 64.5% by weight dihydrocarbon trisulfide, more than about 5.5% by weight dihydrocarbon disulfide, and at least about 30.0% by weight dihydrocarbon tetrasulfide or more; A dihydrocarbon polysulfide component comprising a mixture comprising polysulfide,
(C) containing a trihydrocarbyl phosphite component and having at least 90% by weight of the formula: (RO) ₃ P, wherein R is a hydrocarbon group having 4 to 24 carbon atoms An acidic phosphorus component, and (d) at least one dihydrocarbon dithiophosphate. Gear oil additive package containing a mixture of the following ingredients:
(A) a hydrated alkali metal borate component,
(B) less than 70.0% by weight of dihydrocarbon trisulfide, more than 5.5% by weight of dihydrocarbon disulfide, and at least 30.0% by weight of dihydrocarbon tetrasulfide or higher polysulfide. A dihydrocarbon polysulfide component comprising a mixture comprising
(C) non-comprising a trihydrocarbon phosphite component and having at least 90% by weight of the formula: (RO) ₃ P, wherein R is a hydrocarbon group having 4 to 24 carbon atoms Acidic phosphorus component,
(D) at least one dihydrocarbon dithiophosphate, and (e) a dihydrocarbon phosphite component, of which at least 90% by weight is of the formula: (RO) ₂ POH, where R is a carbon atom A phosphorus component having an alkyl of 4 to 24.   A lubricating oil composition comprising a major amount of lubricating oil and a minor but effective amount of the gear oil additive package of claim 7 to improve the load bearing and friction properties of the lubricating oil composition.   A lubricating oil composition comprising a major amount of lubricating oil and a minor but effective amount of the gear oil additive package of claim 8 to improve the load bearing and friction properties of the lubricating oil composition.   A lubricating oil composition comprising a major amount of an oil of lubricating viscosity and from about 1.0 to about 10.0% by weight of the gear oil additive package of claim 7 or 8.   The gear oil additive package according to claim 7 or 8, wherein the borate is potassium or sodium triborate.   The gear oil additive package according to claim 7 or 8, wherein the dihydrocarbon dithiophosphate is an amine salt of a dithiophosphate.   The lubricating oil composition of claim 1, wherein the major amount of oil of lubricating viscosity is selected from the group consisting of Type I, Type II, Type III, Type IV or Fischer-Tropsch base oil.   The lubricating oil composition of claim 1 comprising a polyalkene co-oligomer.   The lubricating oil composition of claim 15 comprising about 1 to 20 weight percent polyalkene co-oligomer. A method for producing a lubricating oil composition comprising mixing a major amount of oil of lubricating viscosity with the following ingredients:
(A) at least one hydrated alkali metal borate component,
(B) less than about 64.5% by weight dihydrocarbon trisulfide, more than about 5.5% by weight dihydrocarbon disulfide, and at least about 30.0% by weight dihydrocarbon tetrasulfide or more; At least one dihydrocarbon polysulfide component comprising a mixture comprising polysulfide,
(C) comprising at least 90% by mass of a trihydrocarbon phosphite component, and having at least 90% by mass of the formula: (RO) ₃ P, wherein R is a hydrocarbon group having 4 to 24 carbon atoms One non-acidic phosphorus component, and (d) at least one dihydrocarbon dithiophosphate. A method of manufacturing a gear oil additive package comprising mixing the following ingredients:
(A) at least one hydrated alkali metal borate component,
(B) less than about 64.5% by weight dihydrocarbon trisulfide, more than about 5.5% by weight dihydrocarbon disulfide, and at least about 30.0% by weight dihydrocarbon tetrasulfide or more; At least one dihydrocarbon polysulfide component comprising a mixture comprising polysulfide,
(C) comprising at least 90% by mass of a trihydrocarbon phosphite component, and having at least 90% by mass of the formula: (RO) ₃ P, wherein R is a hydrocarbon group having 4 to 24 carbon atoms One non-acidic phosphorus component, and (d) at least one dihydrocarbon dithiophosphate.

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