Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-11-21
2003-03-11
Mullis, Jeffrey (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S256000, C525S263000, C525S267000, C525S273000, C525S299000, C525S301000, C525S309000, C508S110000
Reexamination Certificate
active
06531547
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for preparing block copolymers, block copolymers prepared by the process, additive concentrates and lubricating oil compositions.
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.
Viscosity improvers are usually polymeric materials and are often referred to as viscosity modifiers or viscosity index improvers. Block copolymers are a known class of viscosity improvers.
Dispersants are also well-known in the lubricating art. Dispersants are employed in lubricants to keep impurities, particularly those formed during operation of mechanical devices such as internal combustion engines, automatic transmissions, etc. in suspension rather than allowing them to deposit as sludge or other deposits on the surfaces of lubricated parts.
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.
Dispersant-viscosity improvers are generally prepared by functionalizing, i.e., adding polar groups, to a hydrocarbon polymer backbone.
Hayashi, et al, U.S. Pat. No. 4,670,173 relates to compositions suitable for use as dispersant-viscosity improvers made by reacting an acylating reaction product which is formed by reacting a hydrogenated block copolymer and an alpha-beta olefinically unsaturated reagent in the presence of free-radical initiators, then reacting the acylating product with a primary amine and optionally with a polyamine and a mono-functional acid.
Chung et al, U.S. Pat. No. 5,035,821 relates to viscosity index improver-dispersants comprised of the reaction products of an ethylene copolymer grafted with ethylenically unsaturated carboxylic acid moieties, a polyamine having two or more primary amino groups or polyol and a high functionality long chain hydrocarbyl substituted dicarboxylic acid or anhydride.
Van Zon et al, U.S. Pat. No. 5,049,294, relates to dispersant/VI improvers produced by reacting an alpha, beta-unsaturated carboxylic acid with a selectively hydrogenated star-shaped polymer then reacting the product so formed with a long chain alkane-substituted carboxylic acid and with a C
1
to C
18
amine containing 1 to 8 nitrogen atoms and/or with an alkane polyol having at least two hydroxy groups or with the performed product thereof.
Bloch et al, U.S. Pat. No. 4,517,104, relates to oil soluble viscosity improving ethylene copolymers reacted or grafted with ethylenically unsaturated carboxylic acid moieties then with polyamines having two or more primary amine groups and a carboxylic acid component or the preformed reaction product thereof.
Gutierrez et al, U.S. Pat. No. 4,632,769, describes oil-soluble viscosity improving ethylene copolymers reacted or grafted with ethylenically unsaturated carboxylic acid moieties and reacted with polyamines having two or more primary amine groups and a C
22
to C
28
olefin carboxylic acid component.
Each of these patents is hereby expressly incorporated herein by reference.
For additional disclosures concerning multi-purpose additives and particularly viscosity improvers and dispersants, the disclosures of the following United States patents are incorporated herein by reference:
2,973,344
3,488,049
3,799,877
3,278,550
3,513,095
3,842,010
3,311,558
3,563,960
3,864,098
3,312,619
3,598,738
3,864,268
3,326,804
3,615,288
3,879,304
3,403,011
3,637,610
4,033,889
3,404,091
3,652,239
4,051,048
3,445,389
3,687,849
4,234,435
U.S. Pat. No. 5,530,079, Veregin et al., discloses a polymerization process comprising heating a mixture of a free radical initiator, a stable free radical agent, at least one polymerizable monomer compound, and optionally a solvent.
U.S. Pat. No. 5,401,804, Georges et al., discloses a free radical polymerization process comprising heating a mixture of a free radical initiator, a stable free radical agent, and at least one polymerizable monomer. The stable free radical agent includes nitroxide free radicals. An organic sulfonic or carboxylic acid can be added to increase the rate of polymerization.
U.S. Pat. No. 3,189,663, Nozaki, discloses block copolymers comprising copolymers where the macromolecules are made up of at least two different linear segments. The first is made up of a linear polymer of a member of the group consisting of ethylenically unsaturated carboxylic acids, anhydrides thereof, and their esters and amides. The second segment is made up of a polymer of a dissimilar member of the first group, esters of unsaturated alcohols and saturated acids, alkenes, alkadienes, vinyl halides, vinyl substituted aromatic hydrocarbons, alkenyl-substituted halo-hydrocarbons, and alkenyl ethers.
U.S. Pat. No. 4,581,429, Solomon et al., discloses a process for free radical polymerization to produce relatively short chain length homo- and copolymers. The initiator has the general formula
U.S. Pat. No. 5,608,023, Odell et al., discloses a polymerization process comprising heating a mixture of a free radical initiator, a stable free radical agent, at least one polymerizable monomer compound, and a sulfonic acid salt polymerization rate enhancing compound to form thermoplastic resins.
U.S. Pat. No. 5,449,724, Moffatt et al., discloses a free radical polymerization process which includes heating a mixture comprised of a free radical initiator, a stable free radical agent, and ethylene.
U.S. Pat. No. 5,677,388, Koster et al., relates to a living free-radical polymerization process for preparing polymers from vinyl aromatic monomers comprising polymerizing the vinyl aromatic monomer in the presence of a difunctional nitroxyl initiator.
An object of this invention is to provide a novel process for preparing block copolymers.
Another object is to provide a one-pot, relatively short duration process for preparing block copolymers.
Another object is to provide block copolymers which may be isolated as diluent-free, dry, free-flowing solids.
Another object of this invention is to provide novel block copolymers useful as lubricant additives.
Still another object is to provide lubricants having improved shear stability and viscometric properties.
A more specific object is to provide additives directed to improving lubricant viscometrics.
Other objects will in part be obvious in view of this disclosure and will in part appear hereinafter.
SUMMARY OF THE INVENTION
The present invention provides a process for preparing a block copolymer. In one embodiment, the block copolymers comprise (A) a poly (vinyl aromatic) block and (B) a poly (vinyl aromatic-co-acrylic) block, said process comprising the steps,
(a) polymerizing at an elevated temperature from about 5 to about 95 mole % of a charge comprising at least one vinyl aromatic monomer to prepare a stabilized active polymer block (A), using a free radical polymerization process,
wherein a stable free radical agent is employed during the polymerization, thereby preserving the stabilized active polymerization
Lange Richard M.
Visger Daniel C.
Esposito Michael F.
Mullis Jeffrey
Shold David M.
The Lubrizol Corporation
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