CA1191502A - Method for reducing brake noise in oil-immersed disc brakes - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
"METHOD FOR REDUCING BRAKE NOISE IN OIL-IMMERSED DISC
BREAKS"

Lubricating oils containing borated 1,2-alkane diols have been found to reduce brake noise for oil-immersed disc brakes.

Description

01 ~1--METHOD FOR REDUCING BRAKE NOISE
IN OIL IMMERSED DISC BRAK~S

FIELD OF THE INVE~TION
This invention relates to lubricating oil com-positions, particularly to lubricating oil compositions useful as functi3nal fluids in systems requiring coupling, hydraulic fluids and~or lubrication of relatively moving parts. More particularlyl it is concerned with functional fluids for use in the lubrication of heavy machinery, particularly high~power-output tractors, and to the reduc-tion of brake chatter therein.
DESCRIPTION OF THE PRIOR ART
The use of heavy machinery, such as a tractor, has increased the demand for high-performance lubricating compositions Modern trac~ors have many power-assisted components, such as power s~eering and power brakes.
Power brakes are preferably of the disc ~ype since they have greater braking capacity The pre~erred disc brakes are the wet-t~pe brake, which are immersed in a lubricant and are therefQre isolated from dirt and grime Such brakes suffer from at least one problem, namely, brake chatter or brake squawk, This phenomenon is a very unpleasant noise that occurs upon appli~ation of the brake. In the past, riction-modifying agerlts, such as dioleylhydrogen phosphite, have been added to the brake lubricating composition to reduce the chatter. Lubricat-ing compositions containing this additive tend to sufferfrom very high wear rates, particu1arly at high temperature.
A further complication in eliminating brake chatter is the desire to use the sarne functional fluid~
35 not only for the brake lubrication, but also for lubrica-tion of other tractor parts, such as the hydraulic and mechanical power take-offs, the tractor transmission, gears and bearings, and the like. The functional fluid must act as a lubricant, a power transfer means, and as a heat transfer medium. Obtainirlg a compounded fl-lid to ~J

~r~

~1 --2--meet all of these needs wlthout brake chatter is difficult.
05 U.S. Paten~ No. 3,151,077 teaches the use of borated monoacylated trimethylol alkanes as motor fuel and lubricating oil additives. The addltives are taught to reduce the incidence of surface igni~ion in an lnternal combust~on engine and to inhibit the build-up of car-buretor deposits.
U.SI Patent No. 21795,548 discloses the use oflubricating oil compositions containing borated l,2-alkane diols~ The oil compositions are used in the crankcase of an internal combustion engine in order to reduce oxidation lS of the oil and corrosion of the metal parts of the engine SUMMARY OF THE INVENTION
It has now been found that oil soluble borated 1,2-alkane diols of the Formula l:

R - CH - CH~
O ~ ~0 OH

wherein R is alkyl containing 8 to 28 carbon atoms~ act as appropriace friction-modifying agents, which, when added to a lubricating oil, exhibit good anti-chatter characteristics.
More speciflcally, this invention relates to a method or reducing brake chatter between oilrimmersed disc brakes by lubricating the contac'cing surfaces of said brakes with a composition comprising a major amount of a lubricating oil containing an effective amount to reduce chatter of a borated 1,2-alkane diol of ~he Formula I.
The bora~ed alkane-1,2-diols of the Eormula I
useful in the presenr invention are those having from lO
to 30, preferably 10 to 20 carbon atoms. Single carbon 4~ number species ma~ be employed such as borated decane-1,2 ~l -3-diol, bora~ed octadecarle-1,2-dlol, borated eicosane-1,2 diol, borated tricontane-1,2-diol, and the like, but a ~5 blend of several carbon numbers is preferred. Typical blends include the borated 1,2 diols of 10 to 30 (incl.) carbon atom alkanes; the borated 1,2-diols of 12, 14l 16, 18 and 20 carbon atom alkanes; the borated 1,2-diols of 15 to 20 (incl.) carbon atom alkanes; ~he borated 1,2-diols ~ of 15 to 18 (incl~) carbon a~om alkanes; the bora-ted 1,2-diols of 20 to 24 (incl.) carbon atom alkanes; ~he borated 1,2-diols of 24, 26 and 28 carbon akom alkanes, and the like.
The borated long-chain 1/2-alkane diols are lS prepared by borating a long-chain 1,2-alkane diol of the formula.

I I II
OH OH
wherein R is as defined above, with a stoichiometric amount of boric acicl with removal of the water of reaction by a7.eotropic distillation. The reaction is believed to proceed according to the following scheme:
R - CH - CH2 -~ B(OH)3 solvent ~3 R - CH ~ CH2 ~ l l OH OH ~ \ ~o OH

where R is alkyl containing 8 to 28 carbon atoms.
The reaction may be carried out at a tQmperature in the range of 60C to 135C, in the presence of any suitable organic solvent such as methanol, benzene, x.ylenes, toluenel neutral oil and the like. If the solvent does not form an azeotrope with water, enough of an azeotropic forming agent is included to remove water azeotropically.
~0 ~9-~s~

The diols useful for this invention are either commercially available or are readily prepared from the S corresponding 1-olefin by methods well-known in the art.
For examplel the olefin i5 first reacted with peracid, such as pero~yacetic acid or hydrogen peroxide plus formic acid to form an alkane~1~2-epoxide which is readily hydrolyzed under acid or base catalysis to the alkane-1,2-diol, In another process, the olefin is first halogenated to a 1,2~dihalo-alkane and subsequently hydrolyzed to an alkane~l,2~diol by reaction first with sodium acetate and then with sodium hydroxide.
1-Olefins are available from the thermal crack-ing of waxes. This process produces 012fins of all carbon numbersO l~-Olefins having an even number of carbon atoms are prepared by the well-known ethylene "growth" reactionO
Olefins obtained by either of these processes are essen-tially linear in structure with little or no branching.
Linear olefins are the preferred olefins for conversion into alkane-1,2-diols.
The lubricating compositions used in the process of this invention contain a major amount of a lubricating oil and from about 0.1% to 5.0~ by weight of the borated 1,2-alkane diol of the Formula I, preferably from 005~ to

2~ by weight based on the weight of the total composition.
The optimum amount of a borated 1,2-alkane diol within these ranges will vary slightly depending on the base oil and other additives present in the oil.
Additive concentrates are a]so included within the scope of this invention. In the concentrate additive form, the borated 1~2-alkane diol is preserlt in a concen-tration ranging from 5~ to 50% by weight~
The lubricating compositions are prepared by admixing, using conventional techniques, the appropriate amount of the desired borated 1,2-alkane diol with the lubricating oil. When concentrates are being prepared, the amount of lubricating oil is limited, but is suffi~
cient to dissolve the required amount of bora~ed 1,2-4~ alkane diol. Gener;ll]y, the concentrate will have Z

01 ~5~

sufficient borated l,2-alkane diol to permit subsequent dilution with 1~ to l0 fold more lubricating oilO
~5 The lubricating oil, which may be employed in the practice of this invention, includes a wide variety of hydrocarbon oils derived from synthetic or natural sources, such as naphthenic base~ paraffin base, and mixed base oils as are obtained from the refining of crude oil.
Other lubrica~ing oils derived from shale oil, tar sands or coal are also useful. The lubricating oils may be used individually or in combinations wherever miscible. The lubricating oils generally have a viscosity which ranges from 50 to 5,000 SUS ~Saybolt Universal Seconds)~ and usually from 100 to l,500 SUS at 100Fo The preferred oils have an SAE rating in the range of 10 to 40 and are paraffinic in structure In some tractor systems in which the brake fluid is kept in a separate sump, the hydrocarbon oil/borated l~2-alkane diol composition of ~his invention is a suffi-cient lubricant and can be used as such. Howev r/ in themore usual tractor systems in which there is a common sump for all functional fluids, e.g., transmission lubricant, hydraulic fluid, and the like, the lubricating oil is compounded with a variety of additives. These additives include anti-oxidants, detergents, dispersants, rus~ inhi bitors, foam inhibitors, corrosion inhibitors, anti-wear agents, viscosity index (VI) improvers, friction control agents, elastomer swell agents, extreme pressure (EP) agents, pour point depressants, and metal deactivators All of these additives are well-known in the lubricating oil art.
The preferred additives which may be added to the lubricating oils to which the borated 1~2-alkane diols of the Formula I are added/ are the oil soluble deter gentsl such as the alkali or alkaline earth metal hydrocarbyl sulfonates, or alkali or alkaline earth metal phenates, or mixtures thereof, extreme pressure additives, ~0 ~i -6-such as the Group II metal salt dihydrocarbyl dithiophos-phates and dispersants such as the alkenyl succinimides, ~5 or succinates or mixtures thereof The alkali or alkaline earth metal hydrocarbyl sulfonates may be either petroleum sulonate t synthetic-ally alkylated aromatic sulfonates, or aliphatic sulfo-nates such as those derived from polyisobutylene. One of the more important functions of the sulfonates is to act as a detergent and dispersant. These sulfonates are well-known in the art. The hydrocarbyl group must have a suf~
ficient number of carbon atoms to render the sulfonate molecule oil soluble Preferably, the hydrocarbyl portion lS has at least 20 carbon atoms and may be aromatic or aliphatic, but is usually alkylaromatic. Most preferred for use are calcium, magnesium or barium sulfonates which are aromatic in characterO
Certain sulfonates are typically prepared by sulfonating a pe roleum fraction having aromatic groups, usually mono- or dialkylbenzene groups~ and then forming the metal salt of the sulfonlc acid material~ Other eed-stocks used for preparing these ~ulfonates include syn-thetically alkylated benzenes and aliphatic hydrocarbons ~5 prepared by polymerizing a mono or diolefin, for example~
a polyisobutenyl group prepared by polymerizing isobutene.
The metallic salts are formed directly or by metathesis using well known procedures.
The sulfonates may be neutral or overbased

3~ having base numbers up to about 400 or more. Carbon dioxide is the most commonly used material to produce the basic or overbased sulfonates. Mixtures of neutral and overbased sulonates may be used. The neutral sulfonates are ordinarily used so as to provide from 5 to 25 milli-moles of sulfonate per kilogram of the total composi-tion.
Preferably, the neutral sulfonates are present from 10 to 20 millimoles per kilogram of the total composition and the overbased sulonates are present from 50 to 200 milli~
moles per kilogram of the total composition.

~1 The phenates for use in this invention are those conven~ional products which are the alkali or a]kaline ~5 earth metal salts of alkylated phenols. One of the func tions o ~he phenates is to act as a detergent and disper-sant. The phenols may be mono- or polyalkylated~
The alkyl portion of the alkylphenate is present to lend oil solubility to the phenate. The alkyl portion can be obtained from naturally occurriny or synthetic sources. Naturally occurring sources lnclude petroleum hydrocarbons such as white oil and wax. Being derived from petroleum, the hydrocarbon moiety is a mixture of different hydrocarbyl groups, ~he specific composition of which depends upon the particular oil stock which was used as a startlng materialO Suitable synthetic sources include various commercially available alkenes and alkane derivatives which, when reacted with the phenol, yield an alkylphenol. Suitable radicals obtained include butyl~
hexyl, octyl, decyl, dodecyl, hexadecyl~ eicosyl, tricontyl, and the like~ Other suitable synthetic sources of the alkyl radlcal include olefin polymers such as poly-propylene, polybutylene, polyisobut~lene and the like J
The alkyl group can be straight-chained or branch-chained, saturated or unsaturated (if unsaturatedy preferably containing not more than 2 and generally not more than 1 site of olefinic unsaturation). The alkyl radicals will generally contain from 4 to 30 carbon atoms Generally when the phenol is monoal]cyl~substituted, the alkyl radical should contain at least 8 carbon atoms. The phenate may be sulfurized if desired. It may be either neutral or overbased and if overbased will have a base number of up to 200 to 300 or more. Mixtures of neutral and overbased phenates may be used.
The phenates are ordinarily present in the oil to provide from 10 to 60 millimoles of phena~e per lcilo-gram of the total composition. PreEerably, the neutral phenates are present from 20 to 50 millimoles per lcilogram of the total composltion and the overbased phenates are present frorn 50 to 200 milllmoles per kilogram of the 01 _~_ total composition~ Preferred metals are calcium, magne~
sium, strontium or bariumO
OS The sulfurized alkaline earth metal alkyl-phenates may also be used. These salts are obtained by a variety of processes such as treating the neutralization product of an alkaline earth metal base and an alkylphenol with sulfur. Conveniently the sulur, in elemental form, 1~ is added to the neutralization product and reacted at elevated temperatures to produce the sulfurized alkaline earth metal alkylphenate~
If more alkaline earth metal base were added during the neutralization reaction than was necessary to neutralize the phenol, a basic sul~urized alkaline earth metal alkylphenate is obtained. 5ee, for example7 the process o Walker et al, U~S. Patent No. 2,680,096. Addi-tional basicity can b~ obtained by adding carbon dioxide ~o the basic sulfurized alkaline earth metal alkylphenate.
2~ The excess alkaline earth metal base can be added subse=
quent to the sulfurization step but is conveniently added at the same time as the alkaline earth me~aL base is added to neutrallz~ the phenol.
Carbon dioxide is the most commonly used material to produce the basic or "overbased" phenates~ A
process wherein basic sulfurized alkaline earth metal alkylphenates are produced by adding carbon dioxide is sho~n in ~anneman, U.S. Patent No. 3,178,368~
The Group II metal salts of dihydrocarbyl di-thiophosphoric acids exhibit wear, antioxidan-t and thermal stability properties. Group II metal sal~s of phosphoro-dithioic acids have been described previously. See, for example, U.S. Patent No. 3,390/080~ columns 6 and 71 wherein these compounds and their preparation are des-cribed generally~ Suitabl~, the Group II metal salts Oethe dihydrocarbyl dithiophosphoric acids useful in the lubricating oil composition o this invention contain from about 4 to about 12 carbon atoms in each of the hydro carbyl radicals and may be the same or different and may

4~ be aromatic, alkyl or cycLoalk~l. Preeerred hydrocarbyl

5~

~1 groups are alkyl groups containing from 4 to 8 carbon atoms and are represented by butyl, isobutyl, sec.-butyl, ~5 hexyl, isohexyl, octyl, 2-ethylhexyl ?nd the like~ The metals suitable for forming these salts include barium calcium, strontium, zinc and cadmium~ of whlch zinc is preferred.
Preferably, the Group II metal salt of a dihy-l~ drocarbyl dithiophosphoric acid has the following formulaO

~ P

wherein:
R2 and R3 each independently represent hydrocarbylradicals as described above, and Ml represents a Group II metal ca~ion as described 2 above.
The dithiophosphoric salts are present in the lubricating oil composition in an amount effective to inhibit wear and oxidation of the lu~ricating oil. The preferred amount ranges from about 3 to 30 millimoles of dithiophosphoric sa]t per kilogram of the total composi-tion. Most preferably the salt i5 present in an amount ranging from about 15 to 20 millimoles per kilogram of the tot~l lubricating oil composition.
The alkenyl succinimide or succinate or mixtures thereof are present to, among other things, act as a dis-persant and prevent formatlon of deposits. The alkenyl succinimides and succinates are well-known in the art.
The alkenyl succinimides are the reaction product of a polyolefin polymer-substituted succinic anhydride with an amine, preerably a polyalkylene polyamine, and the alkenyl succinates are the reaction product of a poly~
olefin polymer-substituted succinic anhydride with ~ono-hydric and polyhydric alcohols, phenols and naphthols, preferably a polyhydric alcohol containing at least thr2e ~0 hydroxy radicals. The polyolefin polymer-subs-tituted succini.c anhydrides are obtained by reaction of a polyole:Ein polymer or a derivative thereof with maleic anhyclride. The succinic anhydride thus ob-tained is reacted with the amine or hydroxy compound. The preparation of the alkenyl succinimides has been described many times in the art. See, for example, United States Patent Nos. 3,390,082, 3,219,666 and 3,172,892.
The preparation of the alkenyl succinates has also been described in the art. See, for example, United States Patent Nos. 3,381,022 and 3,522,179.
Particularly good results may be obtained with the lubricating oil compositions of this invention when -the alkenyl succinimide or succinate is a polyisobu-tene~
substituted succinic anhydride of a polyalkylene polyamine or polyhydric alcohol, respectively.
The polylsobutene from which the polyisobutene-substituted succinic anhydride is obtained by polymerizing isobutene and can vary widely in its compositions. The average number of carbon atoms can range from 30 or less -to 250 or more, with a resulting number average molecular weight of about 400 or less to 3,000 or more. Preferably, the average number of carbon atoms per polyisobutene molecule will range from about 50 to about 100 with -the polyisobutenes having a number average molecular weight of about 600 to about 1,500. 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 1,300~ The polyisobutene is reacted with maleic anhydride according to well-known procedures -to yield the polyisobutene-substituted succinic anhydride.

In preparing che alkenyl succinimi.de, the subs-tituted succinic anhydride is reacted wi-th a polyalkylene polyamine to -lO-~, yield the correspondin~3 succinimi~e. Each a:Lkylene radical of the polyalkylene polyamine usually has -lOa-0 1 ~

up to about 8 carbon atoms. The number of alkylene radi~
cals can range up to about 8. The alkylene radical is 0S exemplified by ethylene, propylene, butylene, trimethyl-ene, te~ramethylene, pentamethylene, hexamethylene, octa-methylene~ etc~ The number of amino groups yenerally, but not necessarily, i5 one grea~er than the number of alkylene radicals present in the amine~ i.e., if a poly-alkylene polyamine contains 3 alkylene radicals, it will usually contain 4 amino radicals. The number of aminoradicals ca~ range up to about 9. Preferably/ the alkyl ene radical contains from ahout 2 to about 4 carbon atoms and all amine groups are primary or secondary. In this case~ the number of ~mine groups exceeds the number of alkylene groups by 1. Preferably the polyalkylene polyamine contains from 3 to 5 amine groups. Specific examples of the polyalkylene polyamines include ethylene-diamine, diethyler.etriamine, triethylenete~ramine, propyl-enediamine, t-ripropylenetetramine, tetraethylenepentamine, trimethylenediamine, pentaethylenehexamine, di-(trimethylene)triamine/ tri(hexamethylene)tetramine~ etc.
Other amines suitable for preparing the alkenyl succinimide useful in this invention include the cyclic amines such as piperizine, morpholine and dipiperizines~
Preferably the alkenyl succinimides which may be used in the compositions of this invention have the following formula~

R~ fl-C
I ~ N~Alkylene-NtnH
CH2-C~ A

wherein-a. Rl represents an alkenyl group, preferably a sub-stantially saturated hydrocarbon prepared by polymerizing aliphatic monoolefins. Preferably Rl is prepared from ~1 -12-isobutene and has an average number oE carbon atoms and a number average molecular weight as described above;
~5 b. the ~Alkylene" radical represents a substantially hydrocarbyl group containing up to about 8 carbon a-toms and preferably containing from about 2-4 carbon atoms as described hereinabove;
c. A represents a hydrocarbyl group, an amine-sub-stituted hydrocarbyl group, or hydrogen. The hydrocarbyl group and the amine-substituted hydrocarbyl groups are generally the alkyl and amino-substitu ed alkyl analogs of the alkylene radicals described above~ Preferably represents hydrogen;
d. n represents an integer of from about 1 to 10, and preferably from about 3-5~
The alkenyl succinimide can be reacted with boric acid or a similar boron-containing compound to form borated dispersants having utility in this inven~ion. The borated succinimides are intended to be included within the scope of the term "alkenyl succinimide".
The alkenyl succinates are those of the above-described succinic anhydride with hydroxy compounds which may be aliphatic compounds such as monohydric and poly-hydric alcohols or aromatic compounds such as phenols andnaphthols~ The aromatic hydroxy compounds from which the ~sters may be derived are illustrated by ~he following specific examples: phenol, beta-naphthol, alpha-naphthol, cresol, resorcinol, catehol, p,p' dihydroxybiphenyl, 3a 2-chlorophenol, 2,4~dibutylphenol/ propene tetramer-sub-stituted phenol, didodecylphenol, 4,4'-methylene-bis-phenol~ alpha-decyl-beta-naphthol, polyisobutene(molecular weight of 1000)-substituted phenol, the condensation prod-uct of heptylphenol with 0.5 mole of formaldehyde, the condensaticn product of octylphenol with acetone, di(hydroxyphenyl)oxide, di(hydroxyphenyl)sulfide, di~hydroxyphenyl)disulfide, and ~-cyclohexylphenol.
Phenol and alkylated phenols having up to three alkyl sub~
stituents are preferred. Each of the alkyl subs~ituen~s 4~ may contain 100 or more carbon atoms.

01 -13~

The alcohols from which the esters may be derived preferably contain up to about 40 aliphatic carbon ~S atomsO They may be monohydric alcohols such as methanol, ethanol, isooctanol, dodecanol, cyclohexanol, cyclo-pentanol, behenyl alcohol, hexatriacontanol, neoperltyl alcohol~ isobutyl alcohol, benzyl alcohol, betaphenylethyl alcoholl 2-methylcyclohexanol, beta-chloroethanol, mono-methyl ether of ethylene glycol, monobutyl ether ofethylene glycol, monopropyl ether of die~hylene glycol, monododecyl e~her of triethylene glycol, monooleate of ethylene glycol, monostearate of diethylene glycol~ sec-pentyl alcohol~ tert-butyl alcohol~ 5-bromo~dodecanol, nitro~octadecanol and dioleate of glycerol. The poly-hydric alcohols preferably contain from 2 to about 10 hydroxy radicals~ They are illustrated by, for example, ethylene glycol/ diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol~ tripropylene 2~ glycol, dibutylene glycol, tributylene glycol~ and other alkylene glycols in which the alkylene radical contains rom 2 to about 8 carbon atoms. Other useful polyhydric alcohols include glycerol, monooleate of glycerol, monomethyl ether of glycerol~ pentraerythritol, 9,10-dihydroxy stearic acid, methyl ester of 9,10-dihydroxy stearic acid, 1,2-butanediol, 2,3-hexanediol, 2,4~hexane-diol, pinacol, erythritoll arabitol, sorbitol, mannitol9 1,2-cyclohexanediol, and xylene glycol. Carbohydrates such as sugars~ starches~ celluloses, etcO, likewise may yield esters. The carbohydrates may be exemplified by a glucose, fructose, sucrose, rhamnose~ mannose, glyceralde-hyde, and galactose.
An especially preerred class of polyhycdric alco-hols are those having at least three hydroxy radicals, some of which have been esterified with a monocarboxylic acid having from about 8 to about 30 carbon atoms such as octa-noic acidl oleic acid~ stearic acid, linoleic acicl, dode canoic acid, or tall oil acid. Examples of such partially esteriied polyhydric alcohols are the monooleate of sorbitol, disteara-te of sorbito], rnonoolea-te of glycerol, monostearate of glycerol, di-dodecanoate oF ery-thri-tol.
The esters may also be derived from unsaturated alcohols such as allyl alcohol, cinnamyl alcohol, propargyl alcohol, 1-cyclohexene-3-ol, an oleyl alcohol. S-till other classes of the alcohols capable of yielding the esters of this invention comprises the ether-alcohols and amino-alcohols including, for example, the oxy-alkylene-, oxy-arylene-, amino-alkylene-, and amino-arylene-substituted alcohols having one or more oxy-alkylene, amino-alkylene or amino-arylene oxy-arylene radicals. They are exemplified by Cellosolve, carbitol, phenoxy-ethanol, heptylphenyl-(oxy-propylene)6-H, octyl-(oxyethylene)3o~H, phenyl(oxyoctylene)2-H, mono(heptylphenyl-oxypropylene)-substituted glycerol, polytstyrene oxide), am:ino-ethanol, 3-amino ethyl-pentanol, di(hydroxyethyl)amine, p-aminophenol, tri(hydroxypropyl)amine, N-hydroxyethyl ethylene diamine, N~N,N',N'-tetrahydroxy-trimethylene diamine, and the like. For -the most part, the ether-alcohols having up to about 150 oxy-alkylene radicals in which the alkylene radical contains from 1 to about 8 carbon atoms are preferred.
The esters may be di-esters of succinic acids or acidic esters, i.e., partially esterified succinic acids, as well as partially esterified polyhydric alcohols or phenols, i.e., esters having free alcoholic or phenolic hydroxyl radicals. Mixtures of the above-illustra-ted es-ters likewise are contemplated within the scope of the invention.
The alkeny] succinates can be reacted with boric acid or a similar boron-containiny compound -to form borated dispersants having utility in this invention. Such borated succinates are described in United S-ta-tes Patent No. 3,533,9~5.
The borated succinates are intended to be included within the 5~Z

scope of the term "alkenyl succinate."
The alkenyl succinimide and succinates are present in the lubricatlng oil compositions in an amoun-t -l~a-I

~1 --1 S--effective to act as a dispersant and prevent the deposit of contaminan~s formed in ~he oil. The amount of alkenyl 05 succinimide a~d succinates can range from about 0.5 per-cent to about 20 percent weight of the total lubricatiny oil composition. Preferably the amount of alkenyl suc-cinimide or succinate which may be present in the lubri~
cating oil composition ranges Erom about 2 to about 5 percent by weight of the total composition.
The finished lubricating oil may be single or multigradeO Multigrade lubricating oils are prepared by adding viscosity index (VI~ lmprovers~ Typical viscosity index improvers are polyalkyl methacrylates, ethylene pro-i5 pylene copolymers~ styrene diene copolymers and the likerSo c~lled decorated VI improvers having both viscosity index and dispersant properties are also sui~able for use in the formulations of this invention~
The following examples are ofered to specific-ally illustrate the invention. These examples and illus~
trations are not to be construed in any way as limiting the scope of the invention.
Example 1 A five-liter reaction flask was charged with 1050 grams (4 moles~ of C15~1~ alkane 1,2-diol; 272 grams (4.4 moles) of boric acid and 1500 grams of xyleneO The stirred reaction mixture was hea~ed under reElux for 90 hours. At the end of this time 191 mls of water was col-lectedO The reaction mixture was cooled, filtered and the solvent was removed in vacuo to afford 1158 grams of pro~
duct containing 6.3~ boron.
Example 2 The compositions of this invention were tested in a laboratory test. The test was carried out on an S~E
No. 2 friction machine modified by adding a moderate-speed hydraulic mo~or drive. The te.st specimen was a sandwich of one General ~etals Powder Co. 1500 mix sintered bronze plate between t~o steel spacer plates mounted in the above apparatus. The test fluid, about 300 grams in quantity, 4~ was then charged to the test-oil sump. The hydr~ulic drive rotatecl th~ test specimen~ at 100 rpm. ~ piston-like brake was applied at an apply pre~sure o-f 75 psig.
05 The SAE No. 2 load cell measured the braking torque and an electric tachometer measured rpm. ~n x-y plot~er was used to produce a trace of torque versus rpm as the hydraulic drive was slowly adjusted to decrease the speed to 0 rpm.
The brake chakter performance of a fluid is related to the ~ slope of th~ riction vs~ velocity curve. The slop~ of the curve is found by measuring the slope of a line drawn through the 50 rpm point on the trace and ~he highest point on the trace below 50 rpm. As the slope o-f this curve becomes increasingly negativel th~ brake chatter noise becomes progressively louder. This tendency corre-lates with full scale tractor brake noise tests.
Th~ above described test was run on threemineral oil based tractor hydraulic fluids. The results for these three fluids are shown in Table I~ Composition A was a base without a friction modifier and composi~ion B
contains in addition 1% borated alkanediol of Example lo Composition C is a commercial tractor hydraulic fluid. As shown in Table I, the addition of borated 1,2-alkanediol ~Fluid B) to the base fluid (Fluid A) increased the slope 25 indicating it i~ effective in reducing brake chatterO Also shown in Table 1 is the 510pe ob~ained with a commercial tractor hydraulic fluido 3~

~0 ~3~5~Z

TABLE I
Efect of Borated 1,2~Alkanediol ~5 Upon Laboratory Brake Chatter Simulation Slope of Friction Formulation Velocity Curve A - base oil -.0131 B - base oil + 1% by ~0086 weight Borated 1,2-alkanediol of Example 1 C - Commercial Formulation~0143 3~

~0

Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a lubricating oil composition formulated for use in a tractor and contacting the surfaces of oil-immersed disc brakes, the improvement which comprises adding to said formulated oil from about 0.1% to about 5%
by weight of a borated 1,2-alkane diol of the Formula:

wherein R is alkyl containing 8 to 28 carbon atoms or mixtures thereof.

2. The lubricating oil formulation according to Claim 1 wherein R is alkyl containing 8 to 18 carbon atoms.

3. The lubricating oil formulation according to Claim 2 wherein the borated 1,2-alkane diol is a mixture of borated 1,2-diols containing from 15 to 18 carbon atoms.

4. A method for reducing oil-immersed disc brake chatter by lubricating the contacting surfaces of oil-immersed disc brakes with a composition comprising a lubricating oil containing from about 0,1% to about 5% by weight of a borated 1,2-alkane diol of the formula:

wherein R is alkyl containing from 8 to 28 carbon atoms or mixtures thereof.

5. The method of Claim 4 wherein R is alkyl containing 8 to 18 carbon atoms.

6. The method of Claim 5 wherein the borated 1,2-alkane diol is a mixture of borated 1,2-diols containing from 15 to 18 carbon atoms.