Lubricant including water dispersible base

Abstract

A lubricant in the form of an oil-insoluble solvent e.g. water in oil emulsion is described where a water soluble or water dispersible base is present in the dispersed phase. These lubricants are beneficial in various applications such as internal combustion engines where the oil desirable has enough basicity to neutralize any inorganic acids generated by sulfur present in the fuel.

Description

[0001] Lubricants with excess basicity, characterized as total base number (TBN) are used as lubricants in internal combustion engines where atoms such as sulfur, nitrogen and carbon generate acidic combustion products that cause additional wear. In the past the overbased components where bases were reacted in the oil phase with gases like CO.sub.2 contributed basicity. Water soluble or water dispersible bases can offer more neutralization capacity on a weight basis. The bases can be incorporated into an emulsified water phase.BACKGROUND OF INVENTION[0002] A variety of lubricant oils are available having various total base numbers. One reason for having a total base number above zero in a lubricant is that acidic products are more likely to cause corrosion and wear to metal parts of a device than bases, which tend not to be involved in corrosion. Thus lubricants are formulated with sufficient excess base that over their intended lifetime, they remain neutral or slightly basic.[0003]...

AI Technical Summary

Benefits of technology

[0009] The lubricant can also comprise various conventional lubricating additives to assist in the performance of the lubricant such as dispersants, detergents (including neutral and overbased detergents), extreme pressure agents, antioxidants, viscosity index modifiers, etc. The lubricating oil can be selected from a wide variety of oils of API Groups I through V including mineral oils or combinations of grades or synthetic or combinations with synthetics. A preferred use of the lubricant is as a cylinder lubricant in a marine diesel engine which can burn high sulfur content fuels. The high total base number of the lubricant can minimize the corrosive effect of sulfuric acid on the metal parts of the marine diesel engine. The lubricant can be used in a variety of other applications, such as an internal combustion engine using low sulfur fuel, where an oil with some basicity is beneficial to avoid the effects of acidic reaction products or to extend the useful life of the lubricant.

[0063] In one embodiment, the water-soluble salt (iii) functions as an emulsion stabilizer, i.e., it acts to stabilize the aqueous hydrocarbon lubricant compositions.

[0066] A detergent is an additive that reduces formation of piston deposits, for example high-temperature varnish and lacquer deposits, in engines; it normally has acid-neutralizing properties and is capable of keeping finely divided solids in suspension. Most detergents are based on metal "soaps", that is metal salts of acidic organic compounds, these are sometimes referred to as surfactants.

[0118] Reaction under the conditions described above typically leads to a product which has a relatively high content of --CHO substituent groups, that is, 10%, 12%, and even 15% and greater. Such materials, when used as detergents in lubricating compositions, exhibit good upper piston cleanliness performance, low Cu / Pb corrosion, and good compatibility with seals. Use of metals other than magnesium in the synthesis typically leads to a reduction in the content of --CHO substituent groups.

[0127] Marine cylinder lubricants are used in marine engines including two stroke marine engines in order to provide lubricity, antioxidancy, high temperature detergency and neutralisation of sulphuric acid formed during the combustion. Traditional formulations use overbased detergents for acid neutralisation. The following examples describe a water in lubricant oil emulsion, which uses KOH dissolved in the water phase. KOH is a widely used and non-expensive base. KOH could neutralise the acids formed during the combustion in a more efficient way than the overbased detergents, which would improve the efficiency of the marine cylinder lubricant and reduce the cost of the formulation. The examples also describe the emulsifiers used for the preparation of the water in oil emulsion. These emulsifiers could also contribute to the high temperature detergency.

Problems solved by technology

Due to the high amount of sulfur containing species in the economical residual fuel, the combustion products include high amount of acidic SOX which causes additional wear to the cylinder wall and the rings of the piston.

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