Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Compound of indeterminate structure – prepared by reacting a...
Reexamination Certificate
2002-01-09
2003-04-08
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Compound of indeterminate structure, prepared by reacting a...
C508S235000, C508S471000, C525S327600, C525S327700
Reexamination Certificate
active
06544935
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to nitrogen-containing esterified carboxy-containing interpolymers and to lubricating compositions containing them. More particularly, this invention relates to nitrogen-containing esterified interpolymers derived from low molecular weight olefin or vinyl aromatic compounds and alpha, beta-unsaturated acylating agent, such interpolymers being esterified with aliphatic alcohols and partially neutralized with amino compounds having an average of from about 1 to about 1.1 primary or secondary amino groups. The resulting compositions are particularly useful as viscosity improvers having improved oxidative stability.
BACKGROUND OF THE INVENTION
The viscosity of oils of lubricating viscosity is generally dependent upon temperature. As the temperature of the oil is increased, the viscosity usually decreases, and as the temperature is reduced, the viscosity usually increases.
The function of a viscosity improver is to reduce the extent of the decrease in viscosity as the temperature is raised or to reduce the extent of the increase in viscosity as the temperature is lowered, or both. Thus, a viscosity improver ameliorates the change of viscosity of an oil containing it with changes in temperature. The fluidity characteristics of the oil are improved since the oil maintains a more consistent viscosity over a wider range of temperatures.
Viscosity improvers are usually polymeric materials and are often referred to as viscosity index improvers and sometimes as viscosity modifiers.
Ester group containing polymers are well-known additives for improving the fluidity characteristic of lubricating oils. Polyacrylate, particularly polymethacrylate ester polymers, and esterified carboxy-containing interpolymers are well-known and are widely used for this purpose.
Dispersants are also well-known in the lubricating art. Dispersants are employed in lubricants to keep impurities, particularly those formed during operation of machinery, in suspension rather than allowing them to deposit on the surfaces of parts contacted by the lubricant.
Multifunctional additives that provide both viscosity improving properties and dispersant properties are likewise known in the art. Such products are described in numerous publications including Dieter Klamann, “Lubricants and Related Products”, Verlag Chemie Gmbh (1984), pp 185-193; C. V. Smalheer and R. K. Smith “Lubricant Additives”, Lezius-Hiles Co. (1967); M. W. Ranney, “Lubricant Additives”, Noyes Data Corp. (1973), pp 92-145, M. W. Ranney, “Lubricant Additives, Recent Developments”, Noyes Data Corp. (1978), pp 139-164; and M. W. Ranney, “Synthetic Oils and Additives for Lubricants”, Noyes Data Corp. (1980), pp 96-166. Each of these publications is hereby expressly incorporated herein by reference.
It is also known to improve antioxidant properties of organic compositions such as lubricants and fuel by adding thereto antioxidant compounds such as hindered phenols, sulfur compounds, certain aromatic amines and the like.
It is desirable that the viscosity improver or dispersant viscosity improver not adversely affect the low-temperature viscosity of the lubricant containing same. Frequently, while many viscosity improvers or dispersant viscosity improvers enhance the high temperature viscosity characteristics of lubricating oil, the low temperature properties of the treated lubricant become worse.
Lubricating oils are frequently used in environments that promote oxidation, so it is desirable to manufacture products for use in lubricating oil compositions that do not undergo detrimental degradation under prolonged operating conditions in severe environments.
One of the major requirements for automatic transmission fluids has been improved low temperature performance, the current requirement approximating a maximum Brookfield viscosity of 20,000 centipoise, and more stringent future requirements as low as 10,000 centipoise at −40° C. The viscosity modifier may comprise a significant proportion of the total additive system employed in an automatic transmission fluid and can have a major impact on the low temperature performance. Low temperature performance characteristics are also desirable in other applications such as in gear lubricants. The copolymers of this invention are also useful in many other lubricating oil compositions including, but not limited to engine oils, hydraulic oils, industrial oils, etc.
It is desirable, and a primary object of this invention, to provide compositions that can successfully resist oxidation under use in severe environments.
Another important object is to provide compositions that reduce the extent of loss of viscosity at high temperatures while not adversely increasing the low temperature viscosity of lubricating oil compositions.
Another object is to provide novel additive concentrates containing multi-purpose lubricant additives.
A more specific object is to provide multi-purpose additives directed to improving the viscosity and dispersant properties of a lubricating composition.
Yet another object is to provide lubricants having improved dispersant and viscosity properties.
A further object is to provide lubricants having improved oxidation properties.
Another object is to provide additive concentrates for lubricants, which additive concentrates contain esterified interpolymers that are resistant to shearing.
Other objects will in part be obvious in view of this disclosure and will in part appear hereinafter.
Various pour point depressants, additives which reduce the temperature at which oil will flow freely, have been developed and those to reach the commercial market have primarily been organic polymers, although some monomeric substances such as tetra (long chain alkyl) silicates, phenyl tristearyloxy-silane, and pentaerythritol tetrastearate have been shown to be effective. Presently available commercial pour point depressants are believed to be represented by the following types of polymeric materials: polymethacrylates, for example, copolymers of various chain length alkyl methacrylates (see, for example, U.S. Pat. No. 2,655,479); polyacrylamides (see, for example, U.S. Pat. No. 2,387,501); Friedel-Crafts condensation products of chlorinated paraffin wax with naphthalene (see, for example, U.S. Pat. No. 1,815,022 and 2,015,748); Friedel-Crafts condensation products of chlorinated paraffin wax with phenol (see, for example, U.S. Pat. No. 2,191,498); and vinyl carboxylate, such as dialkyl fumarate copolymers (see, for example, U.S. Pat. Nos. 2,666,746; 2,721,877 and 2,721,878).
Esters of maleic anhydride/alpha-olefin copolymers have been suggested as pour point depressants. For example, U.S. Pat. No. 2,977,334 describes the use of copolymers of maleic anhydride and ethylene which are esterified with low or high molecular weight alcohols and/or amidized with an amine. These resins are described as being useful as pour point modifiers, gelling agents, thickeners, viscosity improvers, etc., for mineral and synthetic oils including functional fluids and lubricating oils. U.S. Pat. No. 2,992,987 describes a class of lubricant additives useful as pour point depressants which are ethylene-maleic anhydride copolymers esterified to 80% or more, preferably 90-100%, with a mixture of straight-chain saturated hydrocarbon alcohols having from 8 to 24 carbon atoms. The unesterified carboxylic groups can be left unreacted or can be reacted with such materials as ethylene or propylene oxide alcohol esters, or lower-dialkylamino-lower-alkylene-amines. U.S. Pat. No. 3,329,658 and 3,449,250 describe copolymers of maleic anhydride and alpha-olefins such as ethylene, propylene, isobutylene or vinyl aromatic compounds such as styrene as being useful dispersancy and detergency additives for oils, as well as pour point depressants and viscosity index improvers. The copolymer is esterified to about 30 to about 95% with aliphatic alcohols or mixtures of alcohols having from 10 to 20 carbon atoms, and the remaining carboxyl groups are reacted with an amine of the following formula:
where R
1
a
Lange Richard M.
Tipton Craig D.
Vargo Daniel M.
Esposito Michael F.
McAvoy Ellen M.
Shold David M.
The Lubrizol Corporation
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