Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heterocyclic ring compound; a heterocyclic ring is one...
Reexamination Certificate
2002-04-15
2003-07-01
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heterocyclic ring compound; a heterocyclic ring is one...
C508S264000, C508S268000, C508S297000, C508S436000
Reexamination Certificate
active
06586375
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to phosphorus salts of dispersant viscosity improvers and lubricating compositions and concentrates containing such salts.
BACKGROUND OF THE INVENTION
Dispersant viscosity improvers are used in lubricating compositions to control the viscosity decrease of the lubricating oils under increasing temperatures. Additionally, these materials have components which improve the oil's ability to suspend or “disperse” impurities in the oil. The dispersing of the impurities prevents them from depositing on the surface of lubricated parts. Polyacrylates, especially polymethacrylate ester polymers, are well known and widely used as viscosity improvers. When these materials have a nitrogen containing monomer, they act as a multifunctional additives providing viscosity improving properties as well as dispersant properties to the lubricating compositions.
Multifunctional additives that provide both viscosity improving properties and dispersant properties are known in the art. Such products are described in numerous publications including C. V. Smalheer and R. K. Smith “Lubricant Additives”, Lezius-Hiles Co. (1967); 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.
Phosphorus containing antiwear agents have been used to prevent adverse wear to metal surfaces of equipment. The phosphorus antiwear agents act to help prevent adverse metal to metal contact.
It is desirable to have a multifunctional additive that provides the benefits of the dispersant viscosity improvers as well as the phosphorus containing antiwear agents.
SUMMARY OF THE INVENTION
This invention relates to a lubricating composition comprising a major amount of an oil of lubricating viscosity and a minor amount of a salt of at least one nitrogen containing polyacrylate and at least one phosphorus acid ester. The invention also relates to lubricating compositions and concentrates containing the same. The present phosphorus salts of the nitrogen containing copolymers provide improved dispersant, viscosity improver and antiwear properties to lubricating compositions. In particular, the salts provide improved viscosity temperature characteristics in finished fluids. The salts also provide improved thermal stability of the lubricating compositions.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the terms “hydrocarbon”, “hydrocarbyl” or “hydrocarbon based” mean that the group being described has predominantly hydrocarbon character within the context of this invention. These include groups that are purely hydrocarbon in nature, that is, they contain only carbon and hydrogen. They may also include groups containing substituents or atoms which do not alter the predominantly hydrocarbon character of the group. Such substituents may include halo-, alkoxy-, nitro-, etc. These groups also may contain hetero atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, sulfur, nitrogen and oxygen. Therefore, while remaining predominantly hydrocarbon in character within the context of this invention, these groups may contain atoms other than carbon present in a chain or ring otherwise composed of carbon atoms.
In general, no more than about three non-hydrocarbon substituents or hetero atoms, and preferably no more than one, will be present for every 10 carbon atoms in the hydrocarbon or hydrocarbon based groups. Most preferably, the groups are purely hydrocarbon in nature, that is they are essentially free of atoms other than carbon and hydrogen.
As used herein, the terms “acrylate” and “acrylamide” includes their alkyl substituted versions, such as lower alkyl acrylates and lower alkyl acrylamides, and especially, methacrylates and methacrylamides. Lower alkyl refers to groups containing 8 or less carbon atoms.
The nitrogen-containing polymers of this invention may be prepared by several different processes. In one embodiment, the nitrogen-containing polymer is obtained by reacting, together, the acrylate ester monomers and the nitrogen-containing monomer. In another embodiment, the nitrogen-containing monomer is grafted onto a preformed acrylate copolymer backbone.
The nitrogen containing polymers generally have weight average molecular weight (Mw) ranging from about 10,000 to about 350,000 or from about 12,000 to about 200,000 or from about 15,000 to about 150,000 or from about 20,000 to about 120,000. Here and elsewhere in the specification and claims range and ratio limits may be combined. Polydispersity of the nitrogen containing polymers (abbreviated PDI for polydispersity index) values (Mw/Mn), where Mn denotes number average molecular weight, range from about 1.2 to about 5, or from about 2 to about 4.
Molecular weights of polymers are determined using well-known methods described in the literature. Examples of procedures for determining molecular weights are gel permeation chromatography (also known as size-exclusion chromatography) and vapor phase osmometry.
The nitrogen containing polymers of the present invention are derived from a majority of acrylate ester monomers. In one embodiment, the ester groups of the acrylate monomers independently contain from about 1 to about 30 carbon atoms, or from about 4 to about 24 carbon atoms. The acrylate monomers are generally derived by esterifying acrylic or methacrylic acid with one or more alcohols. Useful alcohols include methyl alcohol, ethyl alcohol, butyl alcohol, octyl alcohol, iso-octyl alcohol, isodecyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, capryl alcohol, lauryl alcohol, myristyl alcohol, pentadecyl alcohol, palmityl alcohol, stearyl alcohol and the like. The additional alcohols and the acrylate monomers derived therefrom may be used to make the majority of the polymer. These monomers may be used alone or in combination. The alcohols may be reacted with acrylic acid or methacrylic acid to form the desirable acrylates or methacrylates.
The acrylate ester monomers can be prepared by conventional methods well-known to those of skill in the art.
In one embodiment, the nitrogen-containing polymers are derived from (a) from about 5% to about 75% by weight, or from about 30% to about 60% by weight of alkyl acrylate ester monomers containing from 1 to 11 carbon atoms in the alkyl group and (b) from about 25% to about 95% by weight, or from about 40% to about 70% by weight of alkyl acrylate ester monomers containing from 12 to about 24 carbon atoms in the alkyl group. Alkyl methacrylate esters are particularly useful monomers. In another embodiment, monomer (a) comprises at least 5% by weight of alkyl acrylate esters having from 4 to 11 carbon atoms in the alkyl group. In another embodiment, monomer (a) comprises from about 10% to about 40% by weight alkyl acrylate esters having from 1 to 4 carbon atoms in the alkyl group. In still another embodiment, monomer (a) comprises from about 60% to about 90% by weight of alkyl acrylate esters having from 9 to 11 carbon atoms in the alkyl group.
In another embodiment, the nitrogen containing polymers are derived from a mixture of alkyl methacrylate ester monomers containing, (a) from about 9 to about 25 carbon atoms in the ester group, or from about 13 to about 19 carbon atoms, or to about 16 carbon atoms, and (b) from about 7 to about 12 carbon atoms in the ester group, or from about 9 to about 12 carbon atoms, or 9 carbon atoms. In one embodiment, the polymer is derived from ester (a) and (b) and at least one monomer selected from the group consisting of methacrylic acid esters containing from 2 to about 8 carbon in the ester group atoms and which are different from methacrylic acid esters (a) and (b). Typically, the mole ratio of esters (a) to esters (b) in the copolymer ranges from about 95:5 to about 35:65, often from about 90:10 to about 60:40, and frequently from about 80:20 to about 50:50. In on
Gahagan Michael P.
Sivik Matthew R.
Esposito Michael F.
Gilbert Teresan W.
Howard Jacqueline V.
The Lubrizol Corporation
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