EP1046699B1 - Use of non-toxic, biodegradable functional fluids for motor vehicles - Google Patents

Description

The invention relates to the use of non-toxic and biodegradable motor vehicle functional fluids obtained by adding nontoxic and biodegradable functional additives to base fluids of the copolymer type of ethylene oxide and propylene oxide.

Each motor vehicle currently contains a variety of fluids that perform various functions such as engine and / or gear lubricating oils, hydraulic oils such as power steering oil, brake fluid or shock absorber fluid, and the coolant.

When a vehicle is put out of service, all of these fluids must be removed at 95% and disposed of in separate containers or recycled separately, which entails significant costs.

• les inhibiteurs de la corrosion/rouille des pièces métalliques du moteur,
• les agents anti-usure (AW) et extrême-pression (EP) réduisant le frottement par réaction chimique avec la surface métallique,
• les agents dispersants assurant la dispersion et l'évacuation de contaminants solides insolubles,
• les agents détergents évitant la formation de dépôt à la surface des pièces métalliques par dissolution des produits secondaires d'oxydation ou de la combustion,
• les agents augmentant l'indice de viscosité (VI), c'est-à-dire réduisant la diminution de la viscosité du lubrifiant en fonction de la température,
• les agents anti-oxydation inhibant la dégradation par oxydation du lubrifiant, et
• les agents abaissant le point d'écoulement.

Among these functional fluids, the most problematic from an ecological point of view is undoubtedly the motor oil. In fact, the current lubricants mainly use mineral (paraffinic or naphthenic) or synthetic base oils that are little or not biodegradable. To meet the requirements of a specification or a lubricant standard, a base of additives with specific functions is added to this base oil. Examples of such additives may be indicated

• the corrosion / rust inhibitors of the metal parts of the engine,
• anti-wear (AW) and extreme-pressure (EP) agents reducing friction by chemical reaction with the metal surface,
• dispersants dispersing and discharging insoluble solid contaminants,
• the detergent agents avoiding the formation of deposition on the surface of the metal parts by dissolving the secondary oxidation products or combustion,
• viscosity index (VI) increasing agents, that is reducing the decrease in lubricant viscosity as a function of temperature,
• the anti-oxidation agents inhibiting the oxidative degradation of the lubricant, and
• pour point depressants.

Most of these additives have toxicity problems and are not biodegradable or carcinogenic.

Thus, current engine oils pose a serious problem for the protection of the environment because of oil leaks, emission with exhaust gases and failure to control the collection and recycling of a high tonnage of oil. Drainage oils (in Germany, up to 20 to 30% of sales volume) are the source of significant pollution.

One approach to overcome these problems has been to use non-ecotoxic and rapidly biodegradable base fluids.

Thus, the patent application DE A 196 47 554 (Daimler Benz and Fragol Industrieschmierstoffe) discloses a refrigerating and lubricating fluid for life of an internal combustion engine consisting of a carrier fluid based on a copolymer of ethylene oxide and propylene oxide having a average molar mass between 300 and 700 and a weight ratio EO / PO between 30/70 and 70/30, and a mixture of additives.

However, in this application, only the base fluid has a rapid biodegradability greater than 90% and an absence of ecological toxicity.

The patent application EP 0 572 866 discloses ecological and biodegradable functional fluids, consisting of a biodegradable base fluid, preferably selected from polyol esters, and non-toxic additives not presenting ecological risks.

The patent US 5,401,428 discloses water-soluble and biodegradable fluids for machining ferrous and non-ferrous metals comprising polyaspartic acid as a biodegradable antioxidant.

The patent WO 97/30137 (corresponding to DE 196 05 162 ) (Elf Antar) discloses a lubricating composition consisting of at least 70% by weight of at least one C _2-5 monoalkylene _glycol , and up to 30% of a mixture of additives. This composition may also contain a small proportion, especially from 0 to 15% by weight, of a polyalkylene glycol having a molar mass of less than 5000.

However, because of the high volatility of the monoalkylene glycols, the upper limit of the temperature of use of these lubricants is at most 165 ° C. A large part of the additives contained in these lubricants are also toxic and not very biodegradable.

Applicant has now discovered that it is possible to overcome the problems related to the ecotoxicity and recycling of lubricants, hydraulic fluids and coolants of the prior art by using ethylene oxide copolymers and propylene oxide as the sole base fluid for the various functional fluids and adding only nontoxic and rapidly biodegradable additives in a reduced amount.

This use of the same basic fluid makes it possible, when the vehicle is put out of definitive use, to landfill with a single waste number or to reprocess together all the functional fluids made from it. .

Moreover, the use of exclusively non-toxic and biodegradable additives also solves the problem of ecological nuisances in the event of accidental leakage or neglect of fluid recovery.

The subject of the present invention is therefore the use of copolymers of ethylene oxide (EO) and of propylene oxide (PO) as the sole and same basic fluid for the manufacture of the various functional fluids of motor vehicles by addition of suitable non-toxic and biodegradable functional additives.

It also relates to a functional fluid for a motor vehicle containing a base fluid consisting of copolymers of ethylene oxide (EO) and propylene oxide (PO), and various non-toxic and biodegradable functional additives.

Copolymers of ethylene oxide and propylene oxide (hereinafter referred to as EO / PO copolymers) used as base fluid for the manufacture of functional liquids are random copolymers containing from 30 to 90% by weight of units derived from ethylene oxide and from 70 to 10% by weight of units derived from propylene oxide and having a weight average molecular weight of between 300 and 1200.

These base fluids, because of their macromolecular structure, have high viscosity indexes, generally between 140 and 220, which render superfluous the addition of additives whose function is to increase the viscosity index.

The good miscibility with the water of these fluids makes it possible to dispense with dispersant and / or detergent additives during the formulation of lubricants.

The rapid biodegradability (according to CEC L-33-A-94) of these fluids is greater than 70%, and sometimes even greater than 80%.

These copolymers have a good lubricating power that can be attributed to the formation of strongly adsorbed films on the surface of the parts subjected to friction. They also have a very low pour point, below -20 ° C or even below -30 ° C. Their cooling capacity is better than that of mineral oils.

The above-described molecules used according to the present invention as the base fluid for automotive functional liquids should have low volatility. In the field of engines, this volatility is evaluated by measuring the loss of mass by evaporation at high temperature. This loss of mass is determined in Europe by means of the Noack test, of German origin (NF T 60-161, CEC L-40-A-93, DIN 51-581), which consists in heating 65 g of oil at 250 ° C for 1 hour under a vacuum of 20 mm of water.

The base fluids, namely the EO / PO copolymers used according to the present invention must have a volatility (Noack) of less than 7% and preferably less than 4%.

On the other hand, as indicated above with respect to the EO / PO copolymers, the base fluids according to the invention must have a sufficiently low pour point. Flow point (in English: for point ) means the lowest temperature at which the oil still flows when it is cooled, without agitation, under standardized conditions (NF). T 60-105 / ASTM D 97 / ISO 3016).

The EO / PO copolymers and the neopolyol fatty-chain esters forming the base fluids used according to the present invention must have a pour point of less than -20 ° C, and preferably less than -30 ° C, or even lower at -40 ° C.

The object of the present invention is to solve the problems of ecotoxicity and recycling posed by the functional liquids of motor vehicles of the prior art. For this it proposes the use of non-toxic and biodegradable base fluids described above in combination with additives also non-toxic and biodegradable.

The interesting physicochemical properties of the non-additive base fluids described above, such as their high viscosity index, their low pour point and their good lubricating power, make it possible to avoid the use of additives whose function is to reduce improvement of these properties (anti-wear / extreme pressure additives, pour point depressants and viscosity index increasing agent).

The additives used for the production of the various functional fluids are chosen from antioxidants, anti-corrosion / anti-rust agents, pH-regulating agents (buffers), anti-wear agents, anti-hydrolysis agents, agents dispersants and anti-foam agents, all non-toxic and biodegradable.

The non-toxic and biodegradable anti-oxidizing agents are chosen from zinc dialkyldithiocarbamates, alkyl dithiocarbamates such as methyl dithiocarbamate, vitamin E (tocopherol) and derivatives thereof, sterically hindered phenols such as 2,6-di- tert -butyl-4-methylphenol or similar hindered phenols wherein the methyl group at the 4-position is replaced by a higher aliphatic alkyl group, and the dialkyl trisulfides.

The non-toxic and biodegradable anti-corrosion / anti-rust agents are chosen from succinic acid derivatives such as alkylsuccinic and partial esters of succinic acid, and neutral alkylbenzenesulfonates calcium.

Polyaspartic acid is a peptide polymer of aspartic acid capable of fulfilling both the functions of dispersing agent, buffering agent (pH regulator) and antiwear agent. It is preferable to use a polyaspartic acid having a weight average molecular weight of between 1000 and 10,000.

Non-toxic and biodegradable anti-foam agents are for example chosen from polydimethylsiloxanes.

Although, for most applications, the addition of antiwear agents is not necessary, it may be useful in the formulation of motor or gear oils. Suitable anti-wear agents are, for example, zinc dialkyldithiocarbamates, sulphurized olefins, sulfurized unsaturated fatty acid esters, sulphured jojoba oil and vegetable oils which can be sulphidated by trapping and transfer of sulfur from fuel.

This list of additives is of course not exhaustive and can be extended according to the specifications of the different functional fluids that it is desired to manufacture provided that only functional additives that are non-toxic and biodegradable are used.

The amounts of these various additives will of course depend on the nature of the base fluid and the role of the additive. In general, the oxidizing agent (s) are used in a proportion of 0.2 to 3% by weight, the anti-corrosion / anti-rust agent (s) are present in a proportion of 0.05 to 1% by weight, on or anti-wear agents, if present, are added at the rate of 0.1 to 2% by weight, the polyaspartic acid is present in a proportion of 0.3 to 3% by weight, the anti-foaming agent (s) are present in an amount of less than 0.02% by weight and the Anti-hydrolysis agents are present in a proportion of 0.2 to 2% by weight, all these values being related to the base fluid.

In the same way, the total amount of functional additives added will depend on the chemical nature of the base fluid and the application of the final functional fluid. It is generally between 1 and 20% by weight, preferably between 2 and 12% by weight relative to the base fluid.

The functional fluid produced by adding nontoxic and biodegradable functional additives to copolymers of ethylene oxide and propylene oxide, may be for example a motor oil, a gear oil, an oil for automatic transmission, an oil for power steering, a hydraulic fluid for dampers, a brake fluid or a coolant.

Claims (11)

1. Use, for all of the functional fluids of a motor vehicle, of one and the same base fluid comprising a copolymer of ethylene oxide (EO) and propylene oxide (PO) with a weight-average molecular weight comprised between 300 and 1,200 and with a EO/PO weight ratio comprised between 30/70 and 90/10, a volatility (Noack volatility measured according to DIN 51581), of less than 7 %, a viscosity index of greater than 140, a pour point of less than -20°C and a biodegradability according to CEC L-33-A-94 of greater than 70 %, to which one or more non-toxic and biodegradable functional additives appropriate for the specific function are added.
2. Use according to any of the preceding claim, characterized in that said EO/PO copolymers have a volatility (Noack volatility measured according to DIN 51581) of less than 4 %.
3. Use according to any one of the preceding claims, characterized in that said EO/PO copolymers have a pour point of less than -30°C, and most particularly of less than -40°C.
4. Use according to any one of the preceding claims, characterized in that said functional additives are chosen from anti-oxidants, anti-corrosion/anti-rust agents, pH regulators (buffer), anti-wear agents, anti-hydrolysis agents, anti-foaming agents and dispersing agents, all being non-toxic and biodegradable.
5. Use according to claim 4, characterized in that the non-toxic and biodegradable anti-oxidants are chosen from zinc dialkyldithiocarbamates, alkyl thiocarbamates such as methyl dithiocarbamate, vitamin E (tocopherol) and its derivatives, sterically-hindered phenols such as 2,6-di-tert-butyl-4-methyl-phenol or similarly hindered phenols in which the methyl group in position 4 is replaced by an upper aliphatic alkyl group, and dialkyl trisulphides.
6. Use according to claim 4, characterized in that the non-toxic and biodegradable anti-corrosion/anti-rust agent or agents are chosen from derivatives of succinic acid such as alkyl succinic acids and partial esters of succinic acid, and neutral calcium alkylbenzene sulphonates.
7. Use according to claim 4, characterized in that, as dispersing agent, buffering (pH regulator) agent and anti-wear agent, a poly(aspartic acid) is used with a weight-average molecular weight comprised between 1,000 and 10,000.
8. Use according to claim 4, characterized in that, as anti-wear agent, zinc dialkyldithiocarbamates, sulphurized olefins, sulphurized unsaturated fatty acid esters, sulphurized jojoba oil and vegetable oils which are able to be sulphurized by trapping and transfer of sulphur originating from the fuel, are used.
9. Use according to claim 4, characterized in that the non-toxic and biodegradable anti-foaming agents are chosen from polydimethylsiloxanes.
10. Use according to any one of the preceding claims, characterized in that the content of non-toxic and biodegradable functional additives of the functional liquids prepared using the base liquid is comprised between 1 and 20 % by weight, preferably between 2 and 12 % by weight relative to the base fluid.
11. Use according to any one of the preceding claims, characterized in that said prepared functional fluids are chosen from engine oil, gear lubricant oil, automatic-transmission fluids, power-steering fluid, shock-absorber hydraulic fluid, brake fluid and coolant.