FR2513260A1 - LUBRICATING OIL-BASED COMPOSITION CONTAINING BORATE GLYCEROL FATTY ACID ESTERS AND ITS APPLICATION TO BRAKES NOISE MITIGATION - Google Patents

Abstract

THE INVENTION RELATES TO A PROCESS FOR MITIGATION OF BRAKE JAMMING. THE PROCESS CONSISTS OF USING A LUBRICATING OIL FORMULATED FOR USE IN PARTICULAR IN A TRACTOR IN CONTACT WITH BRAKE SURFACES, THE FORMULATED OIL BEING ADDITIONED FROM ABOUT 0.1 TO ABOUT 5 BY WEIGHT OF A FATTY ACID ESTER GLYCEROL BORATE. APPLICATION TO DISC BRAKES OF THE OIL IMMERSE TYPE.

Description

The present invention relates to lubricating oil compositions,

  compositions of this nature useful as functional fluids in

  circuits requiring hydraulic coupling fluids

  The invention more particularly relates to functional fluids intended for hearths used for the lubrication of high-power machines, in particular tractors delivering a large power,

  and the attenuation of brake chatter in these machines.

  The use of powerful machines such

  tractor has accentuated the demand for lubricating

  High Performance Factors Modern tractors have many power-assisted components such as power steering and brake boosters. The brake boosters are preferably of the disc type, because they have greater braking capability. The preferred disc brakes are wet type which are submerged in a lubricant and so are

  protected from dirt and filth.

  These brakes present at least one disadvantage, which is called grazing This phenomenon is a noise

  very unpleasant that occurs when the brake is applied.

  In the past, friction modifiers, such as dioleyl hydrogen phosphite, have been added to the brake lubrication composition to reduce chatter. Lubricating compositions containing this additive tend to have the disadvantage of being very wear resistant.

  quickly, especially at high temperatures.

  The elimination of brake chatter

  in addition to the need to use the same functional fluid not only to lubricate the brakes, but also to lubricate other tractor parts such as hydraulic and mechanical power take-offs, tractor transmission, gears and bearings , etc. The functional fluid must act as a lubricant, as a power transmission medium and as a heat transfer fluid. Obtaining a fluid formulated to meet all these requirements without grazing.

brake is difficult.

  U.S. Patent No. 3,151,077 teaches the use of mono-acyl borate trimethylolalkanes as additives for motor fuels and lubricating oils. This patent teaches that the additives in question reduce the phenomenon of superficial ignition in an internal combustion engine and inhibit the accumulation of

deposits in the carburetor.

  U.S. Patent No. 2,795,548

  discloses the use of lubricating oil compositions

  Borated glycerol mono-oleate containing oils are used in the crankcase of an internal combustion engine to reduce oxidation

  oil and corrosion of the metal parts of the engine.

  The Applicant has just discovered that borated fatty acid esters of glycerol soluble in oil

  act as appropriate friction modifiers

  who, when added to a lubricating oil,

  have good anti-dripping characteristics.

  More particularly, the invention relates to a method for reducing chatter between disk brakes immersed in the oil by lubricating the contact surfaces of said brakes with a composition containing a dominant amount of a lubricating oil containing a fatty acid ester. borated glycerol in a quantity

effective in reducing chatter.

  The borated fatty acid esters of glycerol are prepared by borating a fatty acid ester of glycerol with boric acid, with removal of the water of reaction. Preferably, the boron is present in an amount sufficient for each boron atom reacts with

  1.5 to 2.5 hydroxyl groups present in the reaction mixture

  tional. The reaction can be carried out at a temperature in the range of 60 to 1350 C, in the absence or in the presence of any suitable organic solvent such as methanol, benzene, xylenes, toluene, neutral oil, etc. . Fatty acid esters of glycerol can be prepared by various methods well known in the art. Many of these esters, such as glycerol mono-oleate and glycerol ester of tallow fatty acid, are produced. On an industrial scale The esters which can be used in the present invention are oil-soluble and are advantageously prepared from C 8 to C 22 fatty acids or a mixture thereof.

  acids, as found in natural products.

  The fatty acid may be saturated or unsaturated.

  found in acids from natural sources

  They may contain licanic acid which contains a keto group. Highly preferred C 8 to C 22 fatty acids are those which correspond to the formula R-COOH in which

  R is an alkyl or alkenyl radical.

  Preference is given to the mono fatty acid ester of glycerol; however, mixtures of mono and diesters can be used. Any mixture of monoester and

  diester preferably contains at least 40% mono-ester.

  Mixtures of glycerol mono and diesters contain

  Most preferably, 40 to 60% by weight of the monoester is used.

  For example, the commercial glycerol mono-oleate contains a mixture of 45 to 55% by weight of mono-ester and 55 to

% of diester.

  Preferred fatty acids are oleic, stearic, palmitic, myristic, palmitoleic, linoleic, lauric, linolenic and eleostearic acids and acids derived from natural products such as tallow, palm oil, olive oil, peanut oil, oil males, foot of beef, etc. Oleic acid is a particularly preferred acid. Lubricating compositions used in

  the method of the invention contain a quantity

  of a lubricating oil and about 0.1 to 5.0%

  weight of the borated fatty acid ester of glycerol, preferably

  from 0.5 to 2% by weight based on the weight of the

  total position The optimum amount of a borated fatty acid ester of glycerol in these ranges varies slightly depending on the base oil and other additives present in the oil. Additive concentrates are also within the scope of the invention. In the concentrated form of the additive, the borated fatty acid ester of glycerol is present.

  at a concentration ranging from 5 to 50% by weight.

  Lubricating compositions are prepared

  by mixing, according to conventional techniques, the quantity

  Suitably the Borated Fatty Acid Ester of the Desired Glycerol with the Lubricating Oil When concentrates are prepared, the amount of lubricating oil is limited, but it is sufficient to dissolve the desired amount of the acid ester. Generally, the concentrate contains enough borated fatty acid ester of glycerol to allow the subsequent dilution with

  1 to 10 times more lubricating oil.

  The lubricating oil which can be used in the practice of the invention comprises a large variety of hydrocarbon oils of synthetic or natural origin, for example naphthenic base oils,

  paraffinic and mixed products as obtained by refining

  Other lubricating oils derived from shale, tar sands or coal oil are also useful. Lubricating oils can be used individually or in combination whenever they are miscible. Saybolt viscosity from 50 to 5000 universal seconds, and usually from 100 to 1500 seconds

  universal at 37.80 C The preferred oils have a

  between 10 and 40 and their structure is paraffin-

than.

  In certain tractor circuits in the

  the braking fluid is maintained in a separate housing, the composition formed of a hydrocarbon-oil

  and a borated fatty acid ester of glycerol of the invention

  It is a sufficient lubricant and can be used, however, in the more common tractor circuits in which there is a common crankcase for all

  functional fluids, for example the lubricant for trans-

  mission, hydraulic fluid, etc., lubricating oil

  is formulated with various additives These additives include

  Antioxidants, detergents, dispersants, rust inhibitors, foaming inhibitors, corrosion inhibitors, anti-wear agents, viscosity index (IV) improvers, friction-reducing agents , swelling elastomeric agents, extreme pressure (EP) agents, depressants

  pour point and inhibitors of metal catalysis

  All these additives are well known in the art

lubricating oils.

  The preferred additives which can be added to the lubricating oils to which the borated fatty acid esters of glycerol are added are the detergents

  soluble in oils, such as hydrocarbyl sulpho

  alkali metal or alkaline-earth metal compounds or alkali or alkaline-earth metal phenates or mixtures thereof, extreme pressure additives such as Group II dihydrocarbyldithiophosphates and dispersants such as alkenylsuccinimides or

succinates or mixtures thereof.

  The alkali or alkaline earth metal hydrocarbyl sulfonates can be petroleum sulfonates, synthetic alkylated aromatic sulfonates or aliphatic sulfonates such as those derived from polyisobutylene. One of the most important functions

  sulphonates is their action as a detergent and

  These sulfonates are well known in the prior art.

  The hydrocarbyl group must have a sufficient number of carbon atoms to make the sulfonate molecule

  oil-soluble. Preferably, the hydro-

  carbyl has at least 20 carbon atoms and may be aromatic.

  or aliphatic, but it is ordinarily alkyl-

  The most preferred is the use of calcium, magnesium or barium sulfonates which are of aromatic character. Some sulfonates are normally prepared by the sulfonation of a petroleum moiety carrying aromatic groups, usually mono groups or

  dialkylbenzene, and subsequent formation of the metal salt

  Other fillers used for the preparation of these sulfonates include synthetic alkylated benzenes and aliphatic hydrocarbons prepared by polymerization of a monoolefin or diolefin, for example a polyisobutenyl group.

  prepared by polymerization of isobutene

  are formed directly or by metathesis using

well-known procedures.

  The sulfonates can be neutral or can be overbased, with basicity indices reaching or even exceeding about 400 Carbon dioxide is the most commonly used material for

  produce basic or overbased sulfonates.

  It is possible to use mixtures of neutral sulphonates and

  Overbased sulphonates are usually

  5 to 25 mmol of sulfonate per kg of total composition. Preferably, the neutral sulfonates are present in

  at 20 mmol per kg of the total composition and the sulphate

  overbased fonates are present in proportion

  from 50 to 200 mmol per kg of the total composition.

  The phenates to be used in the present invention are the conventional products which are the alkali metal or alkaline earth metal salts of alkylated phenols. One of the functions of the phenates is their action as a detergent and dispersant.

  be mono-alkylated or polyalkylated.

  The alkyl portion of the alkylphenate is present to give the phenate its solubility in the oil.

  alkyl portion can be obtained from natural sources

  synthetic or natural sources include petroleum hydrocarbons such as white oil and

  paraffin is derived from oil, the hydrocarbon portion

  bonée is a mixture of different hydrocarbyl groups

  the particular composition depends on the base oil

  The suitable synthetic sources include various alkenes and various commercially available alkane derivatives which, when reacted with the phenol, give an alkylphenol. Suitable radicals are:

  radicals butyl, hexyl, octyl, decyl, dodecyl,

  decyl, eicosyl, tricontyl, etc. Other synonymous sources

  Suitable alkyl radicals are the olefinic polymers such as polypropylene, polybutylene, polyisobutylene, and the like. The alkyl group may be a straight-chain or branched-chain, saturated or unsaturated group (if it is not saturated, it preferably contains no more than two sites of olefinic unsaturation, and generally no more than Alkyl radicals generally contain from 4 to 30 carbon atoms. Generally, when the phenol bears a single alkyl substituent, the alkyl radical must contain at least 8 carbon atoms. The phenate may optionally be sulphuretted. It may be neutral or overbased and if it is overbased, it has a basicity index of 200 to 300 or more.

  neutral and overbased phenoxide mixtures.

  The phenates are usually present in the oil so that there are 10 to 60 mololes of phenate per kg of total composition. Preferably, the neutral phinates are present in a proportion of 20 to 50 mmol per

  kg of the total composition and the phenates rendered

  The preferred metals are calcium, magnesium, strontium or baryuimide. The alkylphenates of the alkaline earth metals can also be used. These salts are obtained in amounts of 50 to 200 moles per kg of the total composition. by various methods such as treating the neutralization product of the alkaline earth metal halide and an alkylphenol with sulfur. The sulfur, advantageously in the elemental form, is added to the neutralization product and reacted with high temperatures to produce

  the sulphurated alkaline earth metal alkylphenate.

  If one adds during the neutralization reaction

  a larger amount of alkali metal base

  earthy than necessary to neutralize the phenol, a basic alkaline-earth metal alkylphenantate is obtained (see, for example, the process described in US Patent No. 2,680,096). increase

  basicity by adding carbon dioxide to the alkyl-

  basic alkaline earth metal sulphide phenate The excess alkaline earth metal base can be added after the sulphurization operation, but it is conveniently added

  at the same time as the alkali metal base is added

  earthy to neutralize phenol.

  Carbon dioxide is the most commonly used material for producing basic phenates

  or "overbased" means a process in which alkyls are

  basic alkaline earth metal sulphide phenates are produced by addition of carbon dioxide is shown

  in U.S. Patent No. 3,178,368.

  Group II metal salts of dihydro-

  Carbyldithiophosphoric compounds are endowed with

  Wear, antioxidant and thermal stability Group II metal salts of phosphorodithioic acids have already been described (see, for example, columns 6 and 7 of U.S. Patent No. 3,390,080, in US Pat. which compounds and their preparation are generally described) Group II metal salts of dihydrocarbyldithiophosphoric acids which may be

  used in the lubricating oil composition of the

  The preferred hydrocarbyl groups are alkyl groups containing from 4 to 8 carbon atoms and are represented by butyl, isobutyl, sec-butyl, hexyl, isohexyl, octyl, 2-ethylhexyl, etc. Suitable metals for forming such salts include barium, calcium, strontium,

  zinc and cadmium, among which the most preferred

zinc.

  The Group II metal salt of a di-

  hydrocarbyldithiophosphoric acid advantageously corresponds to the following formula R 20 oe S

R 30 / "PS M 1

  wherein: R 2 and R 3 are each independently of one another hydrocarbyl radicals as defined above, and M 1 represents a Group II metal cation

as defined above.

  The dithiophosphoric salts are present in the lubricating oil composition in an effective amount

  to inhibit wear and oxidation of the lubricating oil.

  The preferred amount is from about 3 to 30 mmol of dithiophosphoric salt per kg of the total composition. The salt is present in particular in an amount of about

  at 20 mmol per kg of the total lubricating oil composition.

fiasco.

  Alkylsuccinimide or succinate or mixtures thereof are present for, among other functions, acting

  as a dispersant and to prevent the formation of deposits.

  Alkenyl succinimides and succinates are well known in the art. Alkenyl succinimides are the reaction product of a substituted succinic anhydride.

  by a polyolefinic polymer with an amine, preferably

  polyalkylenepolyamine, and the alkenylsuccinates are the reaction product of a succinic anhydride substituted with a polyolefinic polymer with alcohols,

  monohydroxy and polyhydroxy phenols and naphthols

  The polyolefin polymer-substituted succinic anhydrides are obtained by reacting a polyolefinic polymer or a polyolefinic derivative thereof with a polyhydric alcohol.

  this polymer with maleic anhydride Succinic anhydride

  The preparation of the alkenylsuccinimides has been described many times in the prior art (see, for example, U.S. Patent Nos. 3,390. 082, N 3 219 666 and N 3 172 892) The preparation

  alkenylsuccinates has also been described in the prior art.

  (see, for example, the United States patents

  N 3 381 022 and N 3 522 179).

  Particularly suitable results can be obtained with the lubricating oil compositions of the invention when the alkenyl succinimide or succinate is a polyisobutene substituted succinic anhydride of a polyalkylene polyamine or, respectively, of a polyhydric alcohol. The polyisobutene from which the polyisobutene-substituted succinic anhydride is derived, is obtained by isobutene polymerization and can vary widely in its compositions. The average number of carbon atoms can range from 30 or less than 30 to 250 or more; which gives a number average molecular weight of about 400 or less than 400 to 3000 or more.

  average number of carbon atoms per molecule of polyiso-

  butene ranges from about 50 to about 100, the polyisobutenes having a number average molecular weight of about 600 to about 1500 The average number of carbon atoms per molecule of polyisobutene is preferably from about 60 to about 90, the number average molecular weight

  from about 800 to 1300 The polyisocyanate is reacted

  butene with maleic anhydride according to well-known methods to form polyisobutene-substituted succinic anhydride. In the preparation of alkenyl succinimide, the substituted succinic anhydride is reacted with

  polyalkylenepolyamine to form the succinimide cor-

  Each alkylene radical of the polyalkylenepoly-

  amine usually comprises up to about 8 carbon atoms The number of alkylene radicals can range up to

  The alkylene radical is illustrated by the radicals

  ethylene, propylene, butylene, trimethylene, tetra-

  methylene, pentamethylene, hexamethylene, octamethylene, etc. The number of amino groups is generally, but not necessarily, one unit higher than the number of alkylene radicals present in the amine, i.e., if a polyalkylene polyamine contains three alkylene radicals it usually contains four amino radicals. The number of amino groups can reach about 9%.

  preferably, the alkylene radical contains about 2 to about

  4 carbon atoms and all amino groups are primary or secondary In this case, the number of groups

  amino exceeds the number of alkylene groups by one unit.

  The polyalkylene polyamine advantageously contains 3 to 5 amino groups. Particular examples illustrating the polyalkylene polyamines include ethylenediamine,

  diethylenetriamine, triethylenetetramine, propylene

  diamine, tripropylenetetramine, tetraethylenepentase

  mine, trimethylenediamine, penta-ethylenehexamine,

  di- (trimethylene) triamine, tri- (hexamethylene) -

tetramine, etc. "

  Other amines which are suitable for the preparation of

  alkenylsuccinimide which can be used in the present invention include cyclic amines

  such as piperazine, morpholine and dipiperizines.

  Alkenylsuccinimides which can be used

  in the compositions of the present invention

  dent advantageously to the general formula: R 1 -CH-C v | N + Alkylene-N + n H I

CH 2-C A

A in which:

  R 1 represents an alkenyl group, advantageously

  an almost saturated hydrocarbon prepared by polymerisation

  Aliphatic mono-olefin R 1 is advantageously prepared from isobutene and has an average number of carbon atoms and a number average molecular weight as defined above; b the "alkylene" radical represents a predominantly hydrocarbyl group containing up to about 8 carbon atoms and, preferably, about 2 to 4 carbon atoms as defined above; c A represents a hydrocarbyl group, a

  amino-substituted hydrocarbyl group or hydrogen.

  The hydrocarbyl group and the hydrocarbyl substituted groups

  killing amino are generally alkyl and alkyl analogues

  amino-substituted alkylene radicals defined below

  A is preferably hydrogen; d N is an integer of about 1 to 10,

and in particular from about 3 to 5.

  The alkenyl succinimide can be reacted with boric acid or a similar boron-containing compound to form the borated dispersants for use in the present invention. Borated succinimides are within the scope of the definition of "alkenyl succinimide". The alkenylsuccinates are those of the succinic anhydride defined above with hydroxyl compounds which may be aliphatic compounds such as

  monohydroxyl and polyhydroxyl alcohols or

  aromatic compounds such as phenols and naphthols.

  The aromatic hydroxyl compounds from which the esters can be prepared are illustrated by the following specific examples: phenol, beta-naphthol,

  alpha-naphthol, cresol, resorcinol, catechol, p, p'-dihydroxy-

  biphenyl, 2-chlorophenol, 2,4-dibutylphenol, propene tetramer substituted phenol, didodecylphenol, 4,4'-methylene-bis-phenol, alphadecyl-beta-naphthol, polyisobutene-substituted phenol with a molecular weight of 1000, condensation product of heptylphenol with

  0.5 mole of formaldehyde, the condensation product of octyl-

  phenol with acetone, di (hydroxyphenyl) oxide, di (hydroxyphenyl) sulfide, di (hydroxyphenyl) disulfide and 4-cyclohexylphenol. Phenol and alkylated phenols having up to 3 alkyl substituents are preferred. contain 100 or more than 100 carbon atoms. The alcohols from which the esters may be derived preferably contain up to about 40 atoms.

  carbon aliphatics These may be monohydric alcohols

  hydroxyls such as methanol, ethanol, iso-

  octanol, dodecanol, cyclohexanol, cyclopentanol,

  behenyl alcohol, hexatriacontanol, neo-alcohol

  pentyl alcohol, isobutyl alcohol, benzyl alcohol, bastaphenyl alcohol, 2-methylcyclohexanol,

  beta-chloroethanol, monomethyl ether of ethylene-

  glycol, ethylene glycol monobutyl ether, ether

  monopropyl ether of diethylene glycol, the monododecyl ether

  that triethylene glycol, the mono-oleate of ethylene-

  glycol, diethylene glycol monostearate, alcohol

  sec-pentyl, tert-butyl alcohol, 5-bromo

  dodecanol, nitro-octadecanol and glycerol dioleate.

  The polyhydric alcohols preferably contain 2 to about 10 hydroxy groups. They are illustrated for example by ethylene glycol, diethylene glycol,

  triethylene glycol, tetraethylene glycol, dipropylene

  glycol, tripropylene glycol, dibutylene glycol,

  tributylene glycol and other alkylene glycols in

  The other alkylene radicals contain 2 to about 8 carbon atoms. Other useful polyhydric alcohols include glycerol, glycerol monooleate, ether, and the like.

  monomethyl glycerol, pentaerythritol, 9,10-

  dihydroxystearic acid, the methyl ester of 9,10-

  dihydroxystearic acid, 1,2-butanediol, 2,3-hexanediol, 2,4-hexanediol, pinacol, erythritol, arabitol, sorbitol, mannitol, 1,2-cyclohexanediol and xylene glycol carbohydrates such as sugars, starches, celluloses, etc. can similarly give esters Carbohydrates can be exemplified by glucose, fructose, sucrose, rhamnose, mannose, glyceraldehyde

and galactose.

  A class of polyhydroxyl alcohols

  Especially preferred are alcohols which carry 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 octanolic acid, oleic acid, stearic acid, acidelinoleic acid, dodecanoic acid or tall oil acid Examples of these partially esterified polyhydric alcohols are sorbitol monooleate, sorbitol distearate, glycerol monooleate, glycerol monostearate,

Erythritol didodecanoate.

  Esters can also be derived from alcohols

  unsaturated alcohols such as allyl alcohol, cinnamyl alcohol

  that propargyl alcohol, 1-cyclohexene-3-ol, a

  Oleyl alcohol There are still other classes of alcohol

  cools capable of giving the esters of the invention,

  taking the ether-alcohols and amino-alcohols such as,

  for example, oxyalkylene-substituted alcohols, oxyalkylene,

  arylene, amino-alkylene and amino-arylene having one or

  several oxyalkylene, amino-alkylene, amino-

  arylene or oxyarylene They are illustrated by the product called "Cellosolve", carbitol, phenoxyethanol, heptylphenyl (oxypropylene) 6-H, octyl (oxyethylene) 30-H,

  phenyl (oxyoctylene) 2-H, mono-substituted glycerol

  (heptylphenyloxypropylene), poly (styrene oxide),

  amino-ethanol, 3-amino-ethylpentanol, di (hydroxypropyl)

  ethyl) amine, p-aminophenol, tri (hydroxypropyl) amine,

  N-hydroxyethylethylenediamine, N, N, N ', N'-tetrahydroxy-

  trimethylenediamine, etc. Most ether-alcohols having up to about 150 oxyalkylene radicals, the alkylene radical of which contains 1 to about 8 carbon atoms,

are preferred.

  The esters may be succinic acid diesters or acidic esters, ie partially esterified succinic acids as well as partially esterified polyhydric alcohols or phenols,

  that is, esters having alcoholic hydroxyl radicals

  However, mixtures of the esters illustrated above are likewise within the scope of the invention. The alkenyl succinates may be reacted with boric acid or a similar boron-containing compound to form borated dispersants for use in the present invention.

  Borate succinates are described in the US Pat.

  United States of America N 3 533 945 Borated succinates

  fall within the definition of the term "alkenyl-

succinate. "

  Alkenylsuccinimides and succinates are present in the lubricating oil compositions in an amount to act effectively as a dispersant and to prevent deposition of formed impurities.

* in the oil The quantity of alkenyl succinimides and

  The amount of alkenyl succinimide or succinate which may be present in the lubricating oil composition is preferably from about 0.5 to about 20% by weight of the total lubricating oil composition. 5% by weight of the total composition. The ready-to-use lubricating oil can be

  monograde or multigrade Multi-lubricating oils

  grades are prepared by the addition of improvers

  viscosity index (IV) Examples of improving agents

  viscosity index are polyalkylmethacrylates,

  ethylene-propylene copolymers, styrene copolymers,

  diene, etc. Viscosity index improvers qualified as "decorated" having both viscosity index improving properties and dispersing properties can also be advantageously used.

  in the formulations of the invention.

  The invention is illustrated by the examples

  following, given in a non-limitative manner.

Example 1

  Preparation of borated glycerol mono-oleate 30.92 g of boric acid and 250 ml of xylene are added to a mixture containing 125.23 g of glycerol monooleate (45 to 55% by weight) and glycerol dioleate (55 g). 45% by weight) The reaction mixture is heated at 99-14 ° C. for about 9.5 hours under a nitrogen atmosphere under azeotropic conditions.

  17.6 ml of water using a Dean Stark separator.

  The reaction product is filtered and evaporated in vacuo at 1350 ° C. in a rotary evaporator to obtain 128.35 g of product. Analysis: 2.42% and 2.52% boron

  hydroxyl number = 32 mg KOH / g Spectroscopic analysis

  The infrared peak of the product shows that there is no hydroxyl extension of the free glycerol type, but that there is, in fact, a strong bond, BO-H, and that there is

  has virtually no B-O-B absorption.

Example 2

  The compositions of the invention have been

  in a laboratory test The test was carried out on a modified SAE N O 2 friction machine by the addition of a hydraulic speed motor drive

  Moderate The test sample consisted of a sample

  a laminate formed of a General Metals Powder Co type 1500 mixed sintered bronze plate disposed between two steel spacers, the assembly being mounted in the above apparatus The test fluid, amount of about 300 g, was then loaded into the test oil pan Hydraulic control made

  rotate the test samples at the speed of 100 rpm.

  A piston-type brake was tightened at a pressure

  0.525 M Pa load cell The SAE No 2 load cell measured the braking torque and an electrical tachometer measured the rotational speed A coordinate recorder was used to plot the torque variation curve as a function of rotational speed, as the hydraulic control was slowly adjusted to reduce speed to 0 rpm.

17 2513260

  of a fluid with respect to the braking of the brakes is pro-

  proportional to the slope of the curve of variation of the friction as a function of the speed The slope of the curve is determined by measuring the slope of a straight line passing through the point at 50 rpm on the graphical representation and the most high on the curve below rpm As the slope of this curve becomes more and more negative, the noise of brake chatter becomes more and more intense This trend is correlated with the effects of brake noise on tractor

at full power.

  The test described above was applied to three mineral oil-based tractor hydraulic fluids. The results obtained for these three fluids

  are reproduced on the table Composition A consist

  was in a base without friction modifier and composition B further contained 1% borated glycerol mono-oleate of Example 1 Composition C is a commercial tractor hydraulic fluid As shown in the table, the addition of borated glycerol mono-oleate (fluid B) to the base fluid <fluid A) raised the slope, thus proving to be able to effectively reduce brake chatter. The table also shows the slope obtained with a hydraulic fluid

for commercial tractor.

BOARD

  Effect of a borated acid ester on the simulation of brake grazing in the laboratory Slope of the friction curve according to the formulation Speed A base oil -0.0131 B base oil + 1% by weight of borated glycerol oleate of Example 1 -0.0092 C commercial formulation -0.0143

Claims (6)

  An improved lubricating oil formulated for use in a tractor and in contact with the disk brake surfaces immersed in an oil, characterized in that the improvement comprises adding to said formulated oil about 0.1 to about 5% by weight of a borated fatty acid ester of glycerol. Lubricating oil formulation according to Claim 1, characterized in that the acid ester   Borated fat of glycerol is a borate glycerol oleate.   Lubricating oil formulation according to Claim 2, characterized in that the borated fatty acid ester of glycerol is a mixture containing 45 to 55% by weight of borated glycerol mono-oleate and 55 to 45% by weight.   weight of borated glycerol dioleate.   Lubricating oil formulation according to Claim 2, characterized in that the borated fatty acid ester of glycerol is glycerol mono-oleate. borate.   Method for attenuating the chatter of disc brakes immersed in oil, characterized in that it consists in lubricating the contact surfaces of the brakes   discs immersed in the oil with a composition   taking a lubricating oil containing from about 0.1 to about 5% by weight of a borated fatty acid ester of glycerol.   Process according to claim 5, characterized   in that the borated fatty acid ester of glycerol is a borate glycerol oleate.   Process according to claim 6, characterized   characterized in that the borated fatty acid ester of glycerol is a mixture containing 45 to 55% by weight of borated glycerol mono-oleate and 55 to 45% by weight of Borated glycerol.   Process according to claim 6, characterized   in that the borated fatty acid ester of glycerol   is glycerol borate mono-oleate.