Diesel fuel and lubricating oil antifoams and methods of use

Abstract

The present invention relates to diesel fuel and lubrication oil defoaming agents, and crude oil demulsifiers, as well as methods for using same. In particular, the defoaming agents and demulsifiers are comprised of copolymers which have structures constituting a backbone of polysiloxane onto which is grafted an organic group. These structures comprise a polymer of the formula MD.sub.xD'.sub.yD".sub.zM, where M is O.sub.0.5Si(CH.sub.3).sub.3, D is a OSi(CH.sub.3).sub.2, D' is OSi(CH.sub.3)R, D" is OSi(CH.sub.3)R', R is a polyhydric C.sub.6-C.sub.28 organic group, R' is a phenol derivative or a long chain aliphatic group or polyethers, z is between 0 and 80, x+y+z is between 10-200, x / z is .gtoreq.1, and x / (y+z) is between about 1 and about 5, or formula M'D.sub.aM' where M' is O.sub.0.5Si(CH.sub.3).sub.2R, a is between 4-10, and R and D are the same as defined above.

Description

BACKGROUND OF THE INVENTION[0001] 1. Field of the Invention[0002] This invention relates to defoaming agents for petroleum products (such as diesel fuel and lubricating oils) and crude oil demulsifying agents, and methods for using them.[0003] 2. Description of Related Art[0004] Diesel fuel is a mixture of a variety of hydrocarbons. Most of the hydrocarbons are aliphatic, but aromatics may be present at up to twenty to twenty-five weight percent of the fuel. The mixture can also include kerosine or gas oil. Diesel fuel is commonly used in motor vehicles, and has a tendency to foam profusely when it is poured into the fuel tank of a motor vehicle. It is therefore desirable to reduce such foaming, which can be accomplished by the addition of a defoamer.[0005] Oil companies treat diesel fuel with organic additives,-such as detergents, cetane improvers, viscosity breakers and occasionally perfumes (collectively referred to as "DAP"). Each oil company has its own preferred DAP which it t...

AI Technical Summary

Benefits of technology

[0025] The advantages of the present invention are made possible by the cografting of the low molecular weight, compact, high polarity organic groups onto a silicone backbone. The substitution of the organic groups surprisingly improves the defoaming ability of the copolymer because it enhances defoaming efficiency and helps to maintain the performance characteristics of the copolymers in diesel fuel wherein water is dispersed or dissolved, and because it allows the complete elimination of foam at low silicon concentration.

Problems solved by technology

Diesel fuel is commonly used in motor vehicles, and has a tendency to foam profusely when it is poured into the fuel tank of a motor vehicle.

Diesel fuels delivered to filling stations also may contain some amount of dispersed or dissolved water which can adversely affect the performance characteristics of previously known defoamers.

The water causes a decay in defoaming characteristics and in some extreme cases, may cause the defoamer to enhance foaming, rather than suppress it.

Such wet defoamers also can result in increased sludge deposition in the fuel tank.

However, these polysiloxane copolymers do not work well in wet diesel fuel because the ethers, as a hydrophilic material, will tend to stabilize the foaming of wet fuel.

A disadvantage of this foam suppressant is that it contains high levels of silicon, which can be harmful to engines.

In addition, it can be incompatible with DAP and does not age well.

Such foaming, in combination with the propensity in moving machinery parts for air to be trapped, can adversely affect the lubricity, which can be detrimental to fast moving parts of machinery.

Consequently, abatement of foam and rapid deaeration of lubricating oils is a serious technical requirement for use of lubricating oils.

However, their use usually results in an undesirably low deaeration rate.

The more efficient the silicone oil defoamer is the more pronounced is the problem of deaeration.

However, their efficiency as defoamers is very low at concentrations between about 10-50 ppm.

While organic defoamers provide a satisfactory deaeration rates, the treat rates are undesirably high, and are even several times higher than the treat rates for silicone oils.