EP0536020A1 - Colloidal products containing boron, sulphur and phosphorus, their preparation and their use as additives for lubricants - Google Patents

Abstract

Colloidal products containing boron and phosphorus which are obtained by a process which comprises: (1) obtaining a borated superbasic alkali or alkaline-earth metal sulphonate; (2) reacting at least one phosphorus sulphide with the borated superbasic sulphonate; and (3) isolating the product obtained. According to an advantageous alternative form, 2,5-dimercapto-1,3,4-thiadiazole or one of its derivatives is added to the reaction mixture. The compounds described can be employed as antiwear and extreme-pressure additives to lubricating oils and greases. <IMAGE> <IMAGE>

Description

The present invention relates to colloidal products containing boron and phosphorus, soluble in mineral oils, obtained by reaction of at least one phosphorus sulfide with at least one alkali or alkaline-earth sulfonate known as "overbased", previously borated.

The present invention also relates to the use of these products as additives in mineral and synthetic lubricant bases. Indeed, the colloidal compounds according to the invention are excellent anti-wear and extreme pressure additives which can be used in the formulation of motor oils, gear oils, hydraulic fluids, lubricants for metalworking , lubricating greases and in general when a lubrication problem requires a high lubricity combined with excellent thermal stability.

In French patent application 2,645,168, the preparation of thiophosphorus compounds is described by reaction of at least one phosphorus sulfide with at least one so-called "overbased" detergent additive. In general, an overbased detergent additive can be defined as consisting of a surfactant consisting essentially of an alkaline or alkaline earth salt of an acidic compound containing oleophilic groups and which maintains in colloidal dispersion salts 'weak mineral acids such as CO ₂ , H ₂ S and alkaline or alkaline earth bases. Furthermore, in this French patent application, the reaction product between phosphorus sulfide and the overbased detergent additive can be subsequently treated with at least one active hydrogen compound which can be water, an alcohol, a phenol, an acid, ammonia, an amine, an amide and / or a mercaptan.

It has now been discovered that it is possible to prepare products having a lower corrosivity towards metals, in particular copper, and improved extreme pressure performance compared to the products described in prior French application 2.645. 168.

Their thermal stability is equivalent to that of the products described in this patent application and is very much greater than that of organic phosphosulfurized extreme pressure additives.

• (1) l'obtention d'un sulfonate alcalin ou alcalino-terreux surbasique boraté ;
• (2) la réaction sur le sulfonate surbasique boraté d'au moins un sulfure de phosphore ; et
• (3) la séparation du produit obtenu.

Thus, the products of the invention can be defined as colloidal products containing boron and phosphorus obtained by a process which comprises:

• (1) obtaining an overbased borated alkaline or alkaline earth sulfonate;
• (2) the reaction on the borated overbased sulfonate of at least one phosphorus sulfide; and
• (3) separation of the product obtained.

Obtaining overbased sulfonates containing alkali or alkaline earth borates from step (1) is well known. The introduction of boron into an overbased sulfonate can be carried out either during its manufacture, or by subsequent treatment of an overbased additive with an acidic compound containing boron. The first so-called co-overbasing technique is described in particular in US Patent 3,679,584 and in French Patent No. 2,612,526. The technique of post-treatment of overbased detergents with boric acid or acid derivatives containing boron is perfectly illustrated by US Patents 3,480,548, 3,829,381, 3,907,691, 3,929,650, 4,965,003 and 4,965 004.

The preferred overbased sulfonates according to the invention for obtaining derivatives containing mineral borates are sodium or calcium sulfonates overbased with sodium carbonate or calcium carbonate. Their alkaline reserve expressed in terms of TBN (equivalent alkalinity expressed in milligrams of KOH per gram of product) is between 50 and 600 (i.e. from 0.9 to 10.7 basic equivalents per kg) and preferably between 150 and 500 ( i.e. 2.6 to 8.9 basic equivalents per kg).

The preparation of overbased additives is well known and is described for example in US patents 2,865,956, 3,150,088, 3,537,996, 3,830,739, 3,865,737, 4,148,740 and 4,505,830 and French patent 2,101 813. There are variants of the overbasing reaction which in particular use preformed carbonates from alkoxides and C0 ₂ before being brought into contact with the alkaline or alkaline earth salt of the acid compound; they are described in particular in US patents 2,956,018, 3,932,289 and 4,104,180.

The sulfonic acids for the manufacture of overbased sulfonates which can be used according to the invention are known and described in numerous patents, for example in French patent 2 101 813, pages 5 to 8. The hydrocarbon portion of the molecule advantageously has a molecular weight at less than 370 to ensure the miscibility of the corresponding sulfonates in mineral oils. They may be so-called "natural" acids, resulting from the sulfonation of petroleum fractions, or synthetic acids prepared by sulfonation of charges prepared by synthetic means: alkenyl hydrocarbons, such as polyisobutenes (US Pat. No. 4,159,956), alkylaryl hydrocarbons such as, for example, post-dodecylbenzenes obtained as bottoms products from the manufacture of dodecylbenzene.

The borated acid compounds which can be used according to the invention are boron oxide, boric acids, boric esters in the presence of water. The preferred acidic compound is orthoboric acid. The reaction without addition of solvent is carried out between 100 and 175 ° C with simultaneous elimination of water and carbon dioxide. A protic solvent can be used, preferably methanol. The reaction temperature is then that of the reflux of methanol. A particularly advantageous technique consists in extracting with methanol solid boric acid contained in an enclosure overhanging the reactor. Another method consists in introducing into the overbased sulfonate optionally diluted with a hydrocarbon solvent brought to the reflux temperature of methanol, a saturated solution of boric acid in methanol with simultaneous evacuation of the methanol vapors.

The borated acid compound is used in an amount such that the molar ratio of boron to the basic equivalent (E.B) of the overbased sulfonate is between 0.01 and 7, and preferably between 0.05 and 3.

In step (2) of the process for preparing the products of the invention, the product from step (1) is reacted with a phosphorus sulfide at a pressure between atmospheric pressure and about 5 bar absolute ( 0.5 MPa) at a temperature between 60 and 200 ° C and preferably between 90 and 150 ° C. The reaction between the phosphorus sulfide, solid reagent and the overbased additive is facilitated by good stirring of the reaction medium and by the possible use of a hydrocarbon solvent. The phosphorus sulfide can be gradually introduced into the reaction medium, but it can also be introduced entirely at the start of handling in the borated overbased compound, optionally dissolved in a hydrocarbon solvent, provided that the temperature of the reaction medium is less than approximately 60 ° C. The reaction is then started by gradually raising the temperature in the ranges indicated above.

The phosphorus sulfides which can be used according to the invention are P 4S7, P ₄ S ₉ , P ₄ S _i0 . P ₄ S ₁ () is the preferred phosphorus sulfide according to the invention. The phosphorus sulfide is used in an amount such that the molar ratio of phosphorus to the basic equivalent (EB) of the overbased sulfonate is between 0.002 and 0.15 and preferably between 0.02 and 0.12. Beyond the molar P / EB ratio = 0.15, the reaction between the overbased sulfonate and the phosphorus sulfide may be incomplete.

During step (2) of the process, a solvent can be used to reduce the viscosity of the medium and to facilitate the contact of the various reagents. As examples of solvents according to the invention, mention may be made of cyclohexane, benzene, toluene, xylenes and generally hydrocarbon fractions having a boiling range between 60 and 200 ° C and preferably between 90 and 150 ° C.

Step (3) of the process for preparing the products of the invention consists in filtering and removing the solvent or solvents that may be used. Filtration can be carried out before the removal of the solvent, for example either on simple cellulose disks or on layers of filtering agents of the diatomite type or of natural silica of volcanic origin. Filtration can also be carried out after removal of the solvents. In this case, it is advantageous to perform the filtration hot, for example from 90 to 120 ° C and under a pressure of 2 to 5 bars. (0.2 to 0.5 MPa).

The distillation of the solvent can be carried out in the reactor itself. The elimination of the last traces is facilitated by a nitrogen stripping. It can also be carried out in a thin film evaporator.

The introduction of additional additives such as antioxidants, dispersants, anti-rust, anti-corrosives, anti-foam, etc ... entering into the constitution of additive packages intended for a specific use can be advantageously carried out during step (3 ) before removing the solvent.

The nature of the products formed by the reaction between overbased sulfonates previously borated and phosphorus sulfides is not known. The additive retains the colloidal state after the reaction according to the invention and dissolves in hydrocarbons, giving clear solutions which are perfectly stable over time.

Dialysis performed according to the method described by AMOS R. and ALBAUGH E.W.: "The determination of additives in lubricants" in "Chromatography in petroleum analysis", published by ALTGELT K.H. and GOW T.H., DEKKER Edit. vol 11, chapter 17, pages 409 to 446 (1979) shows that the phosphorus is found entirely in the non-dialyzed fraction which constitutes the colloidal part and is absent from the dialysate where the low molecular weight species are concentrated.

However, it appears that the composition of the products according to the invention is, surprisingly, different from that of the reaction products of phosphorus sulfides on non-borated overbased sulfonates as shown by the nuclear magnetic resonance spectra of phosphorus which reveal a significantly less complex structure of the phosphorus compounds produced when overbased sulfonates containing alkali or alkaline earth borates are used as reagent (see Figures 1 A and 1 B).

A relatively small amount of alkali or alkaline earth borates is sufficient to modify the course of the reaction with phosphorus sulfides.

The colloidal compounds containing boron and phosphorus according to the invention constitute excellent antiwear and extreme pressure additives. Antiwear and extreme pressure additives are incorporated into lubricants when they are intended to lubricate organs subjected to significant mechanical stresses, such as distribution in heat engines, gears, bearings or stops. Significant mechanical stresses also appear during the machining of metals, whether cutting or forming.

In addition, the colloidal compounds containing boron and phosphorus according to the invention are endowed with a great thermal stability which authorizes their use in lubricants subjected in service to temperatures. Very high temperatures of up to 160 ° C, as in some advanced engines, in heavily loaded transmissions or high speed metal cutting.

The colloidal compounds according to the invention also have more pronounced anticorrosive properties and a weaker odor than the corresponding products not containing boron, which facilitates their use in workshops, for example for cutting or forming metals, without upsetting the staff.

où R = H, avec x = 1, R = groupement hydrocarbyle ou mercaptothiadiazole avec 1 Zx Z 5.The corrosiveness of the colloidal compounds according to the invention is reduced compared to the products described in French patent application 2,645,168. It can be further improved, and this is also part of the invention, by the use of 2.5 -dimercapto-1,3,4-thiadiazole or its derivatives of formula

where R = H, with x = 1, R = hydrocarbyl or mercaptothiadiazole group with 1 Zx Z 5.

Preferred according to the invention are 2,5-dimercapto-1,3,4-thiadiazole or its derivatives, normally insoluble in mineral oils but which can be dissolved in the inorganic colloidal part of the micelles. The addition of 2,5-dimercapto-1,3,4-thiadiazole or its derivatives can occur before or after the reaction with phosphorus sulfide.

2,5-dimercapto-1,3,4-thiadiazole or its derivatives are used in an amount such that the molar ratio of the dimercapto thiadiazole group to the phosphorus provided by the phosphorus sulfide is between 0.03 and 3 and preferably between 0,1 and 1. 2,5-dimercapto-1,3,4-thiadiazole is introduced in the form of powder and its dissolution in the reaction medium is rapid at a temperature greater than or equal to 90 ° C. Other compounds such as bis 2,2 '(5-mercapto-1,3,4-thiadiazole) disulfide require higher dissolution temperatures of up to 130-140 ° C.

The introduction of 2,5-dimercapto-1,3,4-thiadiazole or its derivatives can occur before or after the addition of the phosphorus sulfide from step (2). If it is carried out before, the water formed must be removed beforehand by reaction with the colloidal carbonate, for example by azeotropic entrainment.

In the use of the products of the invention as additives for lubricating oils and greases, they can be incorporated into them, for example at a concentration of 0.1 to 25% by mass, preferably from 1 to 15% by mass .

Lubricating oils (or greases) also generally contain one or more other additives such as additives improving the viscosity index, pour point lowering additives, antioxidants, anti-rust, additives anti-corrosion of copper, anti-foam, dispersants, friction reducers, with which the products of the invention are compatible.

The following examples illustrate the invention. They should in no way be considered as limiting. Examples 1, 4 and 8 are given for comparison.

Example 1 (comparative):

• Ca = 14 % en masse
• P = 1,94 % en masse
• S = 4,6 % en masse

245 g of a calcium sulfonate overbased with calcium carbonate, the TBN of which is 410 mg KOH / g (i.e. a basic equivalent number of 7.32 per kg) and 250 ml of toluene. When the mixture is homogeneous, 6.4 g of 2,5-dimercapto-1,3,4-thiadiazole are introduced and the mixture is heated to 90 ° C. until dissolution. The water formed is entrained by azeotropic distillation, then, the reaction mixture being brought to 90 ° C., 18.7 g (0.042 mole) of P ₄ S _io are gradually introduced into the reactor. The temperature is maintained at 90 ° C for 2 hours, then the reaction mixture is brought to reflux; the temperature stabilizes at 115 ° C and is maintained at this value for 3 hours. After cooling, the product is filtered on a cellulose disc, then the solvent is removed on a rotary evaporator. Finally, 270 g of a product are obtained having the following elementary analysis:

• Ca = 14% by mass
• P = 1.94% by mass
• S = 4.6% by mass

Example 2:

• Ca = 13,6 % en masse
• P = 1,87 % en masse
• B = 1,47 % en masse
• S = 3,4 % en masse

245 g of the calcium sulfonate used in Example 1, 250 ml of toluene and 85 ml of methanol are introduced into a stirred reactor fitted with a soxhlet device. In the cartridge of the soxhlet, we have 23.4 g (0.38 mole) of orthoboric acid. The reaction mixture is then maintained at reflux until complete dissolution of the boric acid. The methanol is then distilled, then the reaction water is entrained by azeotropic distillation. After the reaction medium has cooled, 6.4 g of 2,5-dimercapto-1,3,4-thiadiazole are introduced and, at this stage, the same procedure as that described in Example 1 is then followed. The yield of final product is 278 g containing:

• Ca = 13.6% by mass
• P = 1.87% by mass
• B = 1.47% by mass
• S = 3.4% by mass

Example 3:

• Ca = 13,7 % en masse
• B = 3,35 % en masse
• TBN (ASTM D2896) = 362 mg KOH/g (soit un nombre d'équivalents basiques de 6,46 par kg).

A borated overbased calcium sulfonate is prepared by carbonation of a calcium sulfonate derived from a synthetic sulfonic acid according to the indications of Example 1 of French patent 2 101 813, with the difference that the hydrocarbon solvent used is toluene instead of hexane and the target TBN is 400. After the passage of carbon dioxide, boric acid is added to the reaction medium so that the molar ratio of boron to basic equivalent is 0.45 and the mixture is brought to reflux until complete reaction. The solvents and the water formed during the preceding reactions are removed by distillation. After hot filtration, the product obtained has the following characteristics:

• Ca = 13.7% by mass
• B = 3.35% by mass
• TBN (ASTM D2896) = 362 mg KOH / g (i.e. a number of basic equivalents of 6.46 per kg).

• Ca = 9,31 % en masse
• P = 1,44 % en masse
• B = 2,23 % en masse
• S = 2,5 % en masse

250 g of this borated sulfonate are dissolved in 250 ml of toluene. 6.5 g of 2,5-dimercapto-1,3,4-thiadiazole are then added, then dissolved by heating to 90 ° C. The water formed is entrained by azeotropic distillation, then the reaction mixture being brought to 90 ° C., 19.1 g (0.043 mole) of P ₄ S _io are gradually introduced into the reactor. At this stage, the same procedure as that described in Example 1 is then followed, with the exception that 100 g of 100 neutral oil are added before removing the solvent. 369 g of product are finally obtained having the following composition:

• Ca = 9.31% by mass
• P = 1.44% by mass
• B = 2.23% by mass
• S = 2.5% by mass

Example 4 (comparative):

• Ca = 15,0 % en masse
• P = 1,21 % en masse
• S = 3,4 % en masse

245 g of the overbased calcium sulfonate used in Example 1 and 250 ml of xylene are introduced into a stirred reactor under a nitrogen blanket. After homogenization, the mixture is brought to 90 ° C and 10.9 g (0.025 mole) of P ₄ S ₁₀ are gradually introduced. After 5 hours of reaction at 90 ° C. and cooling, 3.7 g of 2,5-dimercapto-1,3,4-thiadiazole are introduced and the mixture is again heated to 90 ° C. After dissolution the mixture is brought to reflux. The temperature stabilizes at 143 ° C; it is kept at this value for 2 hours. After filtration and elimination of the solvents, 251 g of product are collected, the analysis of which is as follows:

• Ca = 15.0% by mass
• P = 1.21% by mass
• S = 3.4% by mass

Example 5:

• Ca = 14,3 % en masse
• P = 1,15% en masse
• B = 1,55 % en masse
• S = 2,3 % en masse

The same quantities of reagents and the same procedure as in Example 4 are used, but a preliminary treatment is carried out with 23.4 g (0.38 mole) of orthoboric acid according to the technique described in Example 2. The yield of final product is 264 g, the elementary analysis of which is as follows:

• Ca = 14.3% by mass
• P = 1.15% by mass
• B = 1.55% by mass
• S = 2.3% by mass

Example 6:

• sulfonate de calcium surbasique = 250 g
• acide orthoboorique = 59,9 g
• 2,5-dimercapto-1,3,4-thiadiazole = 4,2 g
• P₄S_1O = 12,6 g

The procedure used is that of Example 2, but with an overbased calcium sulfonate from TBN 483 mg KOH / g (number of basic equivalents: 8.62 per kg) and with the following amounts of reagents:

• overbased calcium sulfonate = 250 g
• orthobooric acid = 59.9 g
• 2,5-dimercapto-1,3,4-thiadiazole = 4.2 g
• P ₄ S _1O = 12.6 g

• Ca = 15,7 % en masse
• P = 1,19 % en masse
• B = 3,55 % en masse
• S = 2,4 % en masse

Finally, 289.9 g of product of the following composition are obtained:

• Ca = 15.7% by mass
• P = 1.19% by mass
• B = 3.55% by mass
• S = 2.4% by mass

Example 7:

• Ca = 14,3 % en masse
• P = 1,14 % en masse
• B = 1,55 % en masse
• S = 2,8 % en masse

The same quantities of reagents and the same procedure as those indicated in Example 5 are used, with the difference that 2,5-dimercapto-1,3,4-thiadiazole is replaced by an equivalent quantity of bis 2,2 '(2,5-dimercapto-1,3,4-thiadiazole) disulfide. Finally, after filtration and evaporation of the solvents, 267 g of product having the following composition are recovered:

• Ca = 14.3% by mass
• P = 1.14% by mass
• B = 1.55% by mass
• S = 2.8% by mass

Example 8 (comparative):

• Ca = 14,4 % en masse
• P = 2,76 % en masse
• S = 5,5 % en masse

250 g of the calcium sulfonate used in Example 1 and 250 ml of toluene are introduced into a stirred reactor under a nitrogen blanket. After homogenization, the mixture is brought to 110 ° C., 26.7 g (0.06 mole) of P ₄ S ₁₀ are then introduced gradually and the reaction is continued until the evolution of hydrogen sulfide is stopped. After filtration and evaporation of the toluene, 267 g of product are obtained, having the following composition:

• Ca = 14.4% by mass
• P = 2.76% by mass
• S = 5.5% by mass

Example 9:

• Ca = 13,9 % en masse
• P = 2,53 % en masse
• B = 1,42 % en masse
• S = 2,9 % en masse

The procedure is as in Example 8 above after having previously treated with 22.6 g (0.37 mole) of orthoboric acid according to the technique described in Example 2. After the usual treatments, collects 278 g of product, the analysis of which is as follows:

• Ca = 13.9% by mass
• P = 2.53% by mass
• B = 1.42% by mass
• S = 2.9% by mass

Example 10:

Assessment of thermal stability.

The product of Example 5 is used to formulate a manual transmission oil 75W-80W conforming to the PEUGEOT - CITROEN B71 2315 specification and having the following composition (Formulation A):

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The behavior in thermal stability of this oil is compared to that of a commercial lubricant containing a conventional phosphosulfur additive (Formulation B) meeting the same specification, in test GFC T021 A90 intended to verify the stability of transmission lubricants. The test is carried out at 150 ° C for 192 hours under an air flow of 10 liters / hour.

The insoluble products at the end of the test are determined by the GFC method T022 A90. The following results were obtained:

It appears that the lubricant formulated from the product of Example 5 has better thermal stability than the commercial lubricant.

Example 11:

Evaluation of anticorrosive properties with respect to copper.

Copper corrosion tests are carried out according to the AFNOR M 07-015 method equivalent to the ASTM D130 method, for 3 hours at temperatures of 100, 121 and 150 ° C:

Copper corrosion is less pronounced with additives containing boron, the difference being particularly pronounced for tests carried out at 150 ° C.

Example 12:

Assessment of extreme pressure properties

• Viscosité cinématique à 40°C = 25,5 mm²/s
• Viscosité cinématique à 100°C = 4,7 mm²/s
• Index de viscosité = 101
• Point d'écoulement = -15°C
• Teneur en soufre = 0,46 % en masse

The products according to the invention are evaluated for their extreme pressure properties in a lubricating oil. The mineral oil used is a 130 neutral with the following characteristics:

• Kinematic viscosity at 40 ° C = 25.5 mm ² / s
• Kinematic viscosity at 100 ° C = 4.7 mm ² / s
• Viscosity index = 101
• Pour point = -15 ° C
• Sulfur content = 0.46% by mass

The additives are added to the neutral 130 oil in a concentration such that the phosphorus content of the mixtures is identical and equal to 0.11%.

The tests are carried out on a 4-ball machine according to the PEUGEOT-RENAULT D55 1136 method, in which the seizure load is determined after one-minute tests. The results are presented in the following table.

The presence of boron significantly improves the anti-seize properties. The best result is obtained with the product having the highest boron content. The PEUGEOT-CITROEN B71 2315 specification sets a maximum footprint of the balls of 0.5 mm for a load of 1000 N. The table above shows that only the products containing boron according to the invention are capable of reaching this level of performance.

Example 13:

Nuclear magnetic resonance examination of phosphorus.

The products of Examples 8 and 9 are examined, by ³¹ P NMR on a Brüker CXP 200 apparatus, in solution in deuterated benzene, at ambient temperature and at a frequency of 81 MHz.

The P molar / EB ratio is identical for the two products and equal to 0.125. For the sulfonate previously treated with orthoboric acid (Example 9) the molar B / EB ratio is equal to 0.2.

FIGS. 1 A and 1 B respectively represent the spectra of the products of Examples 8 and 9.

Although obtained with products in solution, the general appearance of the spectra recalls that obtained by NMR of the solid, which confirms that in this type of product the phosphorus is well localized in the mineral micelle. The general appearance of the spectra obtained with and without boron is very different. In the presence of boron, no more bands beyond +50 ppm are observed, a region which seems to correspond to phosphosulfur compounds having a high sulfur content.

Claims (14)

1. Collodal product containing boron and phosphorus, characterized in that it is obtained by a process which comprises: (1) obtaining an overbased borated alkaline or alkaline earth sulfonate; (2) reacting said borated overbased sulfonate with at least one phosphorus sulfide; and (3) separation of the product obtained. 2. Product according to claim 1, characterized in that step (1) is carried out by bringing into play at least one acidic compound containing boron during the manufacture of overbased sulfonate. 3. Product according to claim 1, characterized in that step (1) is carried out by post-treatment of an overbased sulfonate with at least one acidic compound containing boron. 4. Product according to one of claims 2 and 3, characterized and that said acid compound containing boron is boron oxide, a boric acid or a boric ester used in the presence of water. 5. Product according to one of claims 2 to 4, characterized in that said overbased sulfonate is a sodium or calcium sulfonate overbased with calcium or sodium carbonate and has a TBN of 50 to 600. 6. Product according to one of claims 2 to 5, characterized in that in step (1) one operates without solvent at a temperature of 100 to 175 ° C. 7. Product according to one of claims 2 to 5, characterized in that in step (1) one operates in a protic solvent at the reflux temperature thereof. 8. Product according to one of claims 2 to 7, characterized in that in step (1) the acid compound containing boron is used in a molar proportion of 0.01 / 1 to 7/1 relative to l basic equivalent of overbased sulfonate. 9. Product according to one of claims 1 to 8, characterized in that the reaction of step (2) is carried out under a pressure of 1 to 5 bars, at a temperature of 60 to 200 ° C and with a proportion molar of phosphorus sulfide from 0.002 / 1 to 0.15 / 1 relative to the basic equivalent of overbased sulfonate. 10. Product according to one of claims 1 to 9, characterized in that the reaction of step (2) is carried out in a hydrocarbon solvent. 11. Product according to one of claims 1 to 10, characterized in that in step (3) one proceeds to a filtration and the elimination of the solvent (s). 12. Product according to one of claims 1 to 11, characterized in that, during its preparation, 2,5-dimercapto-1,3,4-thiadiazole or one of its derivatives is brought into play, before or after step (2), in a molar proportion of 0.03 to 3 dimercaptothiadiazole groups per gram atom of phosphorus involved. 13. Use of a product according to one of claims 1 to 12 as an additive for oil or lubricating grease. 14. Use according to claim 13 wherein said product is incorporated into the lubricating oil or grease at a concentration of 0.1 to 25% by mass.

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