JPH0412320B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to lubricating oil compositions, particularly functional fluids, hydraulic fluids in systems requiring coupling.
and/or to lubricating oil compositions useful for the lubrication of relatively moving parts. More particularly, the present invention relates to functional fluids for use in lubricating heavy machinery, particularly high-powered tractors, and for reducing the chatter of their brakes. Description of the Prior Art The use of heavy machinery such as tractors has increased the demand for high performance lubricating compositions. Modern tractors have many power operated components such as power steering and power brakes. Disc type power brakes are preferred because they have a relatively large braking capacity. The preferred disc type brake is a wet type brake, which is immersed in lubricant and thus isolated from dirt and grime. Such brakes have at least one problem,
That is, you are bothered by brake chatter or brake squawk. This phenomenon is an extremely unpleasant noise that occurs when braking. In the past, friction-modifying agents such as dioleylhydrogen phospite have been added to brake lubricating compositions to reduce chatter noise. Lubricating compositions containing this additive tend to have very high wear rates, especially at high temperatures. A further complication in reducing brake chatter is that the same functional fluid is used not only to lubricate the brakes, but also to lubricate other systems such as hydraulic and mechanical power take-off, tractor transmission, gears and bearings, etc. The hope is to use it to lubricate tractor parts.
This functional fluid must act as a lubricant, a power transmission means, and a heat transfer medium. It is difficult to obtain a blended fluid that eliminates brake chatter noise and also meets all of these requirements. US Pat. No. 3,151,077 teaches the use of borated monosialylated trimethylol alkanes as motor gasoline and lubricating oil additives. This additive is taught to reduce the incidence of surface ignition and carburetor deposits in internal combustion engines. U.S. Patent No. 2,795,548 includes borated 1,2
- Discloses the use of lubricating oil compositions containing alkanediols. This oil composition is used to prevent oxidation in the crankcase of an internal combustion engine and to prevent corrosion of metal parts of the engine. Summary of the invention Formula, Oil-soluble borated 1,2-alkanediols of the formula (wherein R represents an alkyl group of 8 to 28 carbon atoms) act as suitable friction modifiers and when added to lubricating oils. good anti
It was discovered that it exhibits anti-chatter properties. More particularly, the present invention provides for borating an amount of the formula 1, 2 effective to reduce chatter noise.
- A method for reducing the chatter noise of oil-immersed disc brakes by lubricating the contact surfaces of the same with a composition comprising a predominant amount of lubricating oil containing an alkanediol. Boration of formulas 1 and 2 that are effective in the present invention
-Alkane diols have 10 to 30 carbon atoms,
Preferably it has 10 to 20 pieces. Types with a single carbon number such as borated decane-1,2-diol, borated octadecane-1,2-diol, borated eicosane-1,2-diol, and borated tricontane-1,2-diol can be used. Mixtures of various carbon numbers are also preferred. Typical mixtures include borated alkanes of 10 to 30 carbon atoms, 1,2-diols, borated alkanes of 12, 14, 16, 18 and 20 carbon atoms, 1,2-diols, 15 carbon atoms. Borated 1,2-diol of ~20 alkanes, carbon atoms
Boration of alkanes with 15 to 18 atoms 1,2-diol, boration of alkanes with 20 to 24 carbon atoms Boration of 1,2-diols, alkanes with 24, 26 and 28 carbon atoms 1,2-diol etc. are included. The borated long chain length 1,2-alkane diol has the formula: A long-chain 1,2-alkane diol represented by the formula (wherein R is the same as listed above) is borated with a stoichiometric amount of boric acid, and water is removed by azeotropic distillation. manufactured by This reaction is believed to proceed according to the following equation: (wherein R is an alkyl group having 8 to 28 carbon atoms). This reaction can be carried out in the temperature range of 60-135°C in the presence of any suitable organic solvent such as methanol, benzene, xylene, toluene, neutral oil, etc. If the solvent does not form an azeotrope with water, sufficient azeotropic agent is incorporated to remove the water azeotropically. Diols useful in the present invention are either readily commercially available or readily prepared by methods well known in the art.
For example, olefins can be reacted with peracids such as peracetic acid or hydrogen peroxide plus formic acid to form alkane 1,2-epoxides, which are readily hydrolyzed in the presence of acid or base catalysts. to form an alkane 1,2-diol. In another method, olefins are first halogenated to 1,2-dihalo-alkanes and then hydrolyzed to alkane 1,2-diols by reaction first with sodium acetate and then with sodium hydroxide. . 1-Olefins are obtained by thermal decomposition of wax. Olefins with all carbon numbers can be produced by this method. 1-olefins having an even number of carbon atoms are produced by the well-known ethylene growth reaction. The olefins obtained by either of these methods are of essentially linear structure with little or no branching. Linear olefins are preferred for conversion to alkane-1,2-diols. The lubricating composition used in the method of the present invention has a predominant amount of lubricating oil and approximately
Contains from 0.1 to 5% by weight, preferably from about 0.5 to 2% by weight, of a borated 1,2-alkanediol of the formula. The optimal amount of borated 1,2-alkanediol within these ranges will vary slightly depending on the base oil and other additives present in the oil. Additive concentrates are also included within the scope of this invention in concentrated additive form.
The 1,2-alkanediol is present in a concentration range of 5 to 50% by weight. The lubricating composition is prepared by mixing a suitable amount of the desired borated 1,2-alkanediol with a lubricating oil using conventional methods. When making concentrates, the amount of lubricating oil is limited, but sufficient to dissolve a given amount of borated 1,2-alkanediol. Generally, this concentrate is sufficiently borated that it can later be diluted with 1 to 10 times more lubricating oil.
It may contain diols. The lubricating oils used in the practice of this invention include hydrocarbons from a wide variety of synthetic or natural sources, such as naphthenic base oils, paraffinic base oils, and mixed base oils obtained by refining crude oil. Other lubricants derived from shale oil, tar sands or coal are also useful. These lubricating oils can be used alone or in combination with compatible ones. This lubricant is generally 50 to 5000 SUS (Saybolt Universal Second) in 100〓, and usually
It has a viscosity in the range of 100~1500SUS. Preferred oils have an SAE rating in the range of 10-40 and are of paraffinic structure. In some tractor systems where the brake fluid is stored in a separate sump, the hydrocarbon oil/borated 1,2-alkanediol composition of the present invention serves only as a lubricant and as such used. However, all functional fluids,
In more common tractor systems where there is a common sump for things such as transmission lubricants, hydraulic fluids, etc., the lubricating oil is formulated with various additives. These additives include antioxidants, detergents, dispersants, rust inhibitors, antifoaming agents, corrosion inhibitors, antiwear agents, viscosity index improvers, antifriction agents, and elastomer swell agents. agents), extreme pressure (EP) agents, pour point depressants, and metal deactivators. All of these are well known in the lubricant industry. Preferred additives that may be added to the lubricating oil to which the borated 1,2-alkane diols of the formula are added are alkali metal or alkaline earth metal hydrocarbyl sulfonates or alkali metal or alkaline earth metal phenates or mixtures thereof. extreme pressure (EP) agents such as Group metal salts of dihydrocarbyl dithiophosphates, and dispersants such as alkenyl succinimides or succinates or mixtures thereof. The alkali metal or alkaline earth metal hydrocarbyl sulfonates can be any petroleum sulfonates, synthetically alkylated aromatic sulfonates or aliphatic sulfonates such as those derived from polyisobutylene. One of the important functions of this sulfonate is to act as a detergent and dispersant. These sulfonates are well known in the art. The hydrocarbyl group must have a sufficient number of carbon atoms to render the sulfonate molecule oil-soluble. Preferably the hydrocarbyl moiety is
It has at least 20 carbon atoms and can be aromatic or aliphatic, but is usually alkylaromatic. Most preferred for use are calcium, magnesium or barium which are aromatic in nature.
It is a sulfonate. Certain sulfonates are prepared by sulfonating petroleum fractions having aromatic groups, usually mono- or dialkylbenzene groups, and then forming metal salts of the sulfonic acid material. Other feedstocks used for the production of these sulfonates include synthetically alkylated benzene and the polymerization of mono- or di-olefins, such as polyisobutenyl groups made by the polymerization of isobutene. Contains aliphatic hydrocarbons produced by The metal salts are formed directly or by metathesis by well known methods. This sulfonate can be neutral or overbased with a base number of about 400 or more.
It can also be from. Carbon dioxide is the most commonly used substance to produce basic or overbased sulfonates. Mixtures of neutral and overbased sulfonates can also be used. The neutral sulfonate is normally used in amounts of 5 to 25 mmol of sulfonate per kg of total composition. Preferably, the neutral sulfonate is present in an amount of 10 to 20 mmol per kg of total composition and the overbased sulfonate is present in an amount of 50 to 200 mmol per kg of total composition. The phenate used in the present invention is alkylated
Common products are alkali or alkaline earth metal salts of phenols. One function of this fenate is that of a detergent and dispersant.
The phenol may be mono- or polyalkylated. Alkyl The alkyl portion of the fenate is present to make the fenate oil-soluble. The alkyl moiety can be obtained from naturally occurring or synthetic sources. Naturally occurring raw materials include petroleum hydrocarbons such as white oils and waxes.
Because it is derived from petroleum, the hydrocarbon portion is a mixture of various hydrocarbyl groups, the specific composition of which depends on the particular feedstock used as a starting material. Suitable synthetic raw materials include a variety of commercially available alkenes and alkanes that produce alkyl phenols when reacted with phenols. Suitable groups available include butyl, hexyl, octyl, decyl, dodecyl, hexadecyl, eicosyl, tricontyl, and the like. Other suitable synthetic sources of alkyl groups include polypropylene, polybutylene, polyisobutylene, and the like. The alkyl group can be straight chain or branched, saturated or unsaturated (if unsaturated, the olefinic unsaturation is
(preferably no more than one site and generally no more than one site). Alkyl groups are generally
It has 4 to 30 carbon atoms. Generally, when the phenol is mono-alkyl substituted, the alkyl group should contain at least 8 carbon atoms. If desired, the fenate may be sulfurized. It can be either neutral or overbased, and if overbased, the base number is
Probably 200-300 or more. Mixtures of neutral and overbased phenates can also be used. This fenate is usually 10% per Kg of the total composition.
~60 mmol of fenate is present in the oil. Preferably, the neutral phenate is present in an amount of 20 to 50 mmol per kg of total composition and the overbased phenate is present in an amount of 50 to 200 mmol per kg of total composition. Preferred metals are calcium, magnesium, strontium or barium. Sulfurized alkaline earth metal alkyl phenates can also be used. These salts are obtained by various methods such as treating the neutralization product of an alkaline earth metal base and an alkyl phenate with sulfur. Usually elemental sulfur is added to the neutralization product and reacted at elevated temperatures to form the sulfurized alkaline earth metal alkyl phenate. During the neutralization reaction, a basic sulfurized alkaline earth metal alkali phenate is obtained by adding more alkaline earth metal base than is required to neutralize the phenol. See, eg, Walker at al, US Pat. No. 2,680,096. Additional basicity is obtained by adding carbon dioxide to the basic sulfurized alkaline earth metal alkyl phenate. Although an excess of alkaline earth metal base can be added following the sulfidation step, it is convenient to add it at the same time as the alkaline earth metal base added to neutralize the phenol. Carbon dioxide is the most commonly used substance to produce basic or [overbased] phenates. One method of making basic sulfurized alkaline earth metal phenates by the addition of carbon dioxide is shown in US Pat. No. 3,178,368 to Hanneman. Group metal salts of dihydrocarbyl dithiophosphoric acids exhibit abrasion resistance, antioxidant properties, and thermal stability. phosphoro-dithioic acid
The metal salts of Acid) have been previously described.
See, for example, columns 6 and 7 of US Pat. No. 3,390,080, which generally describe these compounds and methods of making them. Group metal salts of dihydrocarbyl dithiophosphoric acids useful in the lubricating oil compositions of the present invention preferably have about 4 to 12 carbon atoms in each hydrocarbyl group, and these may be the same or different. It may also be an aromatic, alkyl or cycloalkyl group. Preferred hydrocarbyl groups are alkyl groups having 4 to 8 carbon atoms and represented by groups such as butyl, isobutyl, sec-butyl, hexyl, isohexyl, octyl, 2-ethylhexyl, and the like. Suitable metals for forming these salts include barium, calcium, strontium, zinc and cadmium, of which zinc is preferred. The Group metal salt of didihydrocarbyl dithiophosphoric acid is preferably one having the following formula: (wherein R ₂ and R ₃ each independently represent a hydrocarbyl group as described above and M ₁ represents a Group metal cation as described above). present in an effective amount for anti-wear and oxidation protection. Its preferred amount is about 3 to 30 per kg of total composition.
dithiophosphate in amounts in the millimolar range. Most preferably, the salt is present in an amount of about
It is present in an amount ranging from 15 to 20 mmol. The alkenyl succinimide or succinate or mixtures thereof are present, inter alia, to act as a dispersant and to prevent the formation of deposits. The alkenyl succinimides and succinates are well known in the art. The alkenyl succinimide is the reaction product of a polyolefin polymer-substituted succinic anhydride with an amine, preferably a polyalkylene polyamine, and the alkenyl succinimide is the reaction product of a polyolefin polymer-substituted succinic anhydride with mono- and polyhydric alcohols, phenols and naphthols, Preferably it is a reaction product with a polyhydric alcohol having at least three hydroxyl groups. Polyolefin polymer-substituted succinic anhydrides are obtained by reaction of polyolefin polymers or derivatives thereof with maleic anhydride. The succinic anhydride thus obtained is reacted with an amine or hydroxy compound. The preparation of alkenyl succinimides has been described many times in the art. See, eg, US Patent Nos. 3,390,082, 3,219,666, and 3,172,892, the disclosures of which are incorporated herein by reference. The preparation of alkenyl susuccinates has also been described in the art. See, eg, US Pat. No. 3,381,022 and US Pat. No. 3,522,179, the disclosures of which are also incorporated herein by reference. Particularly good results will be obtained in the lubricating oil compositions of the present invention when the alkenyl succinimide or succinate is a polyisobutene-substituted succinic anhydride of a polyalkylene polyamine or polyhydric alcohol, respectively. Polyisobutene, from which polyisobutene-substituted succinic anhydride is obtained, is obtained by polymerization of isobutene and its composition varies over a wide range. The average number of carbon atoms ranges from 30 or less to 250 or more, and the corresponding number average molecular weight is approximately
They range from 400 or less to 3000 or more. Preferably, the average number of carbon atoms per polyisobutene molecule is from about 50 to about 100, and accordingly the number average molecular weight of the polyisobutene is from about 600 to about 1500.
It is. More preferably, the average number of carbon atoms per polyisobutene molecule ranges from about 60 to about 90, and the number average molecular weight ranges from about 800 to 1300.
Polyisobutene is reacted with maleic anhydride to form polyisobutene-substituted succinic anhydride by well known methods. In the production of alkenyl succinimides, substituted succinic anhydrides are reacted with polyalkylene polyamines to form the corresponding succinimides. Polyalkylene Each alkylene group of the polyamine usually has up to 8 carbon atoms. Examples of this alkylene group are ethylene, propylene,
They are butylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, and octamethylene. The number of amino groups is generally, but not necessarily, one greater than the number of alkylene groups present in the amine, i.e. when the polyalkylene polyamine contains 3 alkylene groups, it is usually 4 Contains 2 amino groups. The number of amino groups ranges up to about 9. Preferably the alkylene group contains about 2 to about 4 carbon atoms and all amine groups are primary or secondary. In this case, the number of amine groups is one more than the number of alkylene groups. Preferably, the polyalkylene polyamine contains 3 to 5 amine groups. Specific examples of polyalkylene polyamines include ethylene diamine, diethylene-triamine, triethylene tetraamine, propylene
These include diamine, tripropylene tetraamine, tetraethylene pentamine, trimethylene diamine, pentaethylene hexamine, di-(trimethylene)triamine, tri(hexamethylene)tetraamine, and the like. Other amines suitable for preparing alkenyl succinimides useful in the present invention include cyclic amines such as piperidine, morpholine and diperidine. Preferably, the alkenyl succinimide that can be used in the compositions of the invention is one having the formula: (wherein a R ₁ is a substantially saturated hydrocarbon prepared by polymerization of an alkenyl group, preferably an aliphatic monoolefin. Preferably, R ₁ is prepared from isobutene and contains a number of carbon atoms. the average number and number average molecular weight are as described above. b [alkylene] groups are substantially hydrocarbyl groups having up to 8 carbon atoms, preferably from about 2 to 2, as hereinbefore described. having 4 carbon atoms. c A represents a hydrocarbyl group, an amine-substituted hydrocarbyl group, or hydrogen. The hydrocarbyl and amine-substituted hydrocarbyl groups generally include the alkyl and amino groups of the alkylene group as described above. -substituted alkyl analogs (preferably A is hydrogen; dn is an integer from about 1 to 10, preferably about 3 to 5). The compounds can be reacted to form borated dispersants useful in the present invention. This borated succinimide is intended to be encompassed within the term "alkenyl succinimide". Alkenyl succinates are the reaction products of the aforementioned succinic anhydride with hydroxy compounds which may be aliphatic compounds such as monohydric or polyhydric alcohols or aromatic compounds such as phenols and naphthols. Aromatic hydroxy compounds from which esters are derived include phenols,
beta, naphthol, alpha, naphthol, cresol, resorcinol, catechol, p,
p'-dihydrobiphenyl, 2-chlorophenol, 2,4-dibutylphenol, propenetetramer-substituted phenol, didodecyl phenol, 4,4'-methylene-bis-phenol, alpha-decyl-beta-naphthol, polyisobutene (molecular weight 1000 )-substituted phenols, condensation products of 0.5 mole formaldehyde and heptyl phenol, condensation products of acetone and octyl phenol, di-(hydroxy phenyl) oxide, di(hydroxy phenyl) sulfide, di(hydroxy phenyl) bisulfide and 4-cyclohexyl phenol. Phenols and alkylated phenols with up to three alkyl substituents are preferred. Each alkyl substituent may contain 100 or more carbon atoms. The alcohol from which the ester is derived preferably contains about 40 aliphatic carbon atoms. These are methanol, ethanol, isooctanol, dodecanol, cyclohexanol, cyclopentanol, behenyl alcohol, hexatriacontanol, neopentyl alcohol, isobutyl alcohol, benzyl alcohol, beta phenyl ethyl alcohol,
2-Methylcyclohexanol, beta chloro ethanol, monomethyl ether of ethylene glycol, monobutyl ether of ethylene glycol, monopropyl ether of diethylene glycol, monododecyl ether of triethylene glycol, monooleate of ethylene glycol, sec-pentyl alcohol, tert-butyl alcohol, 5-bromododecanol,
It may also be a monohydric alcohol such as nitro octadecanol, and dioleate of glycerin.
Preferably, the polyhydric alcohol has 2 to about 10 hydroxyl groups. Give examples of these, e.g.
Ethylene glycol diethylene glycol, triethylene glycol, tetraethylene
glycols, dipropylene glycol, tripropylene glycol, dibutylene glycol, tributylene glycol and other alkylene glycols in which the alkylene group has from 2 to about 8 carbon atoms. Other useful polyhydric alcohols include glycerin, monooleate of glycerin, monomethyl ether of glycerin, pentaerythritol, 9,10-dihydroxy stearic acid, methyl ester of 9,10-dihydroxy stearic acid, 1,2-butane diol, 2,3-hexane diol,
Includes 2,4-hexane diol, pinacol, erythritol, arabitol, sorbitol, mannitol, 1,2-cyclohexane diol and xylene glycol. Carbohydrates such as sucrose, starch, cellulose, etc. also produce similar esters. Examples of carbohydrates are glucose, fructose, sucrose, rhamnose, mannose, glyceraldehyde and galactose. A particularly preferred class of polyhydric alcohols has at least three hydroxyl groups, some of the hydroxyl groups being from about 8 to about 30, such as caprylic acid, oleic acid, stearic acid, linoleic acid, lauric acid or tall oil. It is esterified with a monocarboxylic acid having 5 carbon atoms. Examples of polyhydric alcohols that are partially esterified in this way are sorbitol monooleate, sorbitol distearate, and erythritol didodecaate. This ester also contains allyl alcohol,
It may also be derived from unsaturated alcohols such as cinnamyl alcohol, pyropargyl alcohol, 1-cyclohexan-3-ol, and oleyl alcohol. Further classes of alcohols from which the esters of the invention may be formed include, for example, one or more oxy-alkylenes,
Included are oxy-alkylene-, oxy-arylene-, amino-alkylene- and amino-arylene-substitutions with amino-arylene or oxy-arylene groups. Examples of these include Cellosolve, Carbitol,
Phenoxy-ethanol, heptyl phenyl-
(oxypropylene) ₆ -H, octyl-(oxyethylene) ₃₀ -H, phenyl(oxyoctylene) ₂ -H, mono(heptyl phenyl-oxypropylene) substituted glycerin, poly(styrene oxide), amino-ethanol, 3- Amino ethyl-pentanol, di(hydroxy ethyl) amine, p-amino phenol, tri(hydroxy propyl) amine, N-hydroxy ethyl ethylenediamine, N,N,
N′N′-tetrahydroxy trimethylene diamine, etc. Generally, ether alcohols having up to 150 oxy-alkylene groups, where the alkylene groups have 1 to about 8 carbon atoms, are preferred. The esters are diesters or acid esters of succinic acid, i.e. partially esterified succinic acid, likewise partially esterified polyhydric alcohols or phenols, i.e. with free alcoholic or phenolic hydroxyl groups. Ester may also be used. Mixtures of the esters exemplified above are likewise intended to be included within the scope of this invention. Alkenyl succinates can be reacted with boric acid or similar boron-containing compounds to form borated dispersants useful in the present invention. Regarding such borated succinates, US Pat. No. 3,533,945, the disclosure of which is incorporated herein by reference. The borated succinates are intended to be encompassed by the term "alkenyl succinates." The alkenyl succinimide and succinate are present in the lubricating oil composition in an effective amount to act as a dispersant and to act as a deterrent to contaminants formed in the oil. The amount of alkenyl succinimide and succinate ranges from about 0.5% to about 20% by weight of the total lubricating oil composition. Preferably, the amount of alkenyl succinimide or succinate that may be present in the lubricating oil composition ranges from about 2% to about 5% by weight of the total composition. The finished lubricant may be single or multigrade. Multigrade lubricating oils are produced by the addition of viscosity index improvers. Typical viscosity index improvers are polyalkyl methacrylates, ethylene propylene copolymers, styrene diene copolymers, and the like. So-called decorated improvers combine the properties of both viscosity index and dispersant and are also suitable for use in the compositions of the invention. The following examples are presented to further demonstrate the invention. These examples are not intended to limit the scope of the invention in any way. Example 1 Into the reaction flask of 5, 1050 g (4 moles) of
C _15-18 alkane 1,2-diol, 272g (4.4
mol) of boric acid and 1500 g of xylene were charged. The mixture was stirred and heated under reflux for 90 minutes. By the end of this time 191 ml of water had been collected.
The reaction mixture was cooled, filtered, and the solvent removed in vacuo to yield a product containing 6.3% boron, 1158
I got g. Example 2 Compositions of the invention were tested in laboratory tests. This test was modified by adding a moderate speed hydraulic motor drive.
It was carried out using a SAENo.2 friction machine. The test piece was made by sandwiching a piece of General Metal Powder Co. 1500 mix sintered onto a bronze plate between two steel spacers placed on the test machine. Approximately 300g of test fluid
The test-oil sump was then charged. The specimen was rotated at 100 rpm by hydraulic operation. A piston brake was applied with a working pressure of 75 psig. SAENo.2
The load cell is used to detect braking torque (braking torque).
torque) and the rotational speed with an electric tachometer. Automatic drawing machine (X-Y plotter) that traces torque against rpm as hydraulic operation gradually decelerates to 0 rpm.
Manufactured by. The brake chatter performance of a fluid is related to the slope of the friction versus velocity curve.
This slope is determined by measuring the slope of a line passing through the 50 rpm point on the trace and the highest point on the trace below 50 rpm. As the slope of this curve becomes increasingly negative, the brake chatter noise becomes progressively louder. This trend correlates with full-scale tractor noise testing. The above tests were tested on three mineral oil base tractor hydraulic fluids. The results for these three fluids are shown in Table 1. Composition A
is the base without friction modifier and composition B
contains the 1% borated alkane diol addition of Example 1. Composition C is a commercial tractor hydraulic fluid. As can be seen from Table 1, borate is added to the base oil fluid (fluid A).
Addition of 1,2-alkanediol (Fluid B) increased the slope indicating its effectiveness in reducing brake chatter. Table 1 also shows the gradients obtained with commercial tractor hydraulic fluids. 【table】

Claims (1)

[Claims] 1 formula, (wherein R represents an alkyl group having 8 to 28 carbon atoms) A composition comprising a lubricating oil containing about 0.1 to 5% by weight of a borated 1,2-alkanediol or a mixture thereof of the formula: A method for reducing chatter noise of an oil-immersed disc brake, characterized by lubricating the contact surface of the oil-immersed disc brake. 2. A method according to claim 1, wherein R is an alkyl group having 8 to 18 carbon atoms. 3 Borated 1,2-alkane diol whose borated 1,2-alkane diol has 15 to 18 carbon atoms.
The method according to item 2 above, wherein the method is a mixture of diols.