Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-03-16
2003-06-24
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S080000, C526S189000, C526S190000, C526S229000, C526S323200, C526S325000
Reexamination Certificate
active
06583247
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to processes for the copolymerization of a diester and an unsaturated polycarboxylic acid ester in the presence of a peroxide catalyst. In particular, the present invention relates to the copolymerization of vinyl acetate and specific diesters, for example, dialkyl fumarate-vinyl acetate copolymers (FVA copolymers). FVA copolymers are particularly useful as lube oil flow improvers (LOFIs) or pour point depressants in lubricating oils as well as wax crystal modifiers for fuels and middle distillates.
BACKGROUND OF THE INVENTION
In the field of lubricating oil additives, it has been known for many years that various polymers and copolymers can be used as additives for improving a number of the desirable characteristics of these lubricating oils. For instance, certain of these additives have been found to be useful for improving the viscosity index or the rate of change of viscosity of various oil compositions with changes in temperatures, and/or for improving the pour point of lubricating oils, that is lowering the temperature at which they lose their flow properties, as well as other such lubricating oil properties. In particular, it has been known for many years that various polymers and copolymers of acrylate esters, and polymers and copolymers of alpha-beta unsaturated polycarboxylic acid esters have potential utility for such purposes. These compounds, and particularly the copolymers of vinyl acetate and dialkyl fumarates, have been found to be particularly useful for such purposes. Thus, these fumarate vinyl acetate copolymers have been used commercially as lubricating oil additives, primarily because of their ability to act as lubricating oil flow improvers. These compounds can also be used as wax crystal modifiers, such as cloud point depressants for diesel fuels, and as flow improvers for middle distillates and heavy fuels.
Cashman et al, U.S. Pat. No. 2,825,717, discloses that these additives can be produced by the copolymerization of certain polycarboxylic acid esters, and most particularly fumaric acid diesters and maleic acid diesters, with other polymerizable materials, such as vinyl compounds, and most particularly vinyl acetate, in the presence of a peroxide catalyst, in an alkaline medium. The processes disclosed in Cashman et al include both bulk polymerization and solution polymerization processes in which the reaction is run at temperatures of up to 250° F., but preferably between about 100° and 200° F., and in the presence of an alkaline medium. An alkaline medium is essential to the Cashman et al process apparently in order to neutralize the residual acid in the first step of the Cashman et al process in which the fumarate is prepared. Commercial processes for the production of these additives are often conducted in the presence of a solvent, such as heptane, hexane, or cyclohexane.
Tutwiler et al, U.S. Pat. No. 2,936,300, discloses processes for the copolymerization of vinyl acetate with a dialkyl fumarate in which the reactants are mixed with a solvent or diluent such as white oil in the presence of peroxide catalysts, such as benzoyl peroxide, with cooling to absorb the heat of polymerization so that the reactions are run at temperatures of from 50° to 125° C. (122° to 257° F.). Also, Young et al, U.S. Pat. No. 3,507,908, discloses the copolymerization of dialkyl fumarate with vinyl esters in the presence of a trialkyl aluminum catalyst utilizing a solvent polymerization reaction. These patents are typical of those processes in which it has been believed that the presence of a solvent was essential not only to maintain a workable viscosity, but even more importantly to act as a chain transfer agent in order to terminate these free radical catalytic reactions. It was also believed that the presence of a solvent was required so that its evaporation would moderate the reaction temperatures of these exothermic reactions.
Other patents have discussed bulk polymerization processes of various kinds. These include Voss et al, U.S. Pat. No. 2,200,437, in which vinyl esters of organic acids, including vinyl acetate, are polymerized in the presence of peroxides of the fatty acids containing at least 16 carbon atoms, with the patentee contending that they unexpectedly discovered that by using such catalysts higher molecular weight polymerization products can be produced, specifically compared to the use of catalysts such as dibenzoyl peroxide and the like. In particular, in example 4 of this patent the vinyl acetate is copolymerized with maleic acid dimethyl ester with oleic acid peroxide at 80° C. (176° F.). This disclosure does not mention, however, the fumarates as a candidate for any of the copolymerization reactions thereof. The maleic acid esters of Voss et al are not, however, nearly as effective as pour point depressants as are the fumarate copolymers of the present invention. Trulacs et al, U.S. Pat. No. 4,220,744, discloses other bulk polymerization processes, in this case employing acrylic monomers and minor quantities of alpha, beta-unsaturated monomers therewith.
U.S. Pat. No. 4,772,674 (C. K. Shih, et al.), the disclosure of which is incorporated herein by reference, discloses a solventless process for producing dialkyl fumarate-vinyl acetate copolymers using a peroxide catalyst; the copolymers are disclosed as being useful as lubricating oil and fuel oil additives.
Redpath et al, U.S. Pat. No. 5,939,365, the disclosure of which is incorporated herein by reference, discloses that higher molecular weight (i.e., 50,000 to 350,000 Daltons) FVA copolymers can be made by changes in conventional process conditions, including reaction temperature, residence time, free radical initiator concentration, number of initiator additions during reaction and the molar ratio of vinyl acetate to dialkyl fumarate (VA:DAF). Furthermore, such higher molecular FVA copolymers were demonstrated to significantly improve low temperature properties of formulated oils comprising an alkylewne/alkylene viscosity index copolymer and to perform particularly well in catalytic and isodewaxed basestocks at competitive treat rates and are expected to perform well in other lubricant and fuel applications, including power transmission fluids, gear oils, tractor hydraulic fluids (THF). However, improvements obtained by employing, in particular, lower reaction temperatures to increase the molecular weight of the copolymer tend to increase the viscosity of the reaction mixture, making it more difficult to mix and pump the copolymer. Furthermore, use of a lower reaction temperature can also reduce the reaction rate.
Other patents disclose copolymerization of the class of copolymers of interest in the present invention, but each of these is directed to the specific nature of the copolymer components or their precursors in order to achieve a particular improvement in performance. Included in this group of disclosures is U.S. Pat. No. 2,618,602 (Bartlett), U.S. Pat. No. 4,088,589 (Rossi et al.), U.S. Pat. No. 3,250,715 (Wyman), U.S. Pat. No. 4,713,088 (Tack), U.S. Pat. No. 4,661,121 (Lewtas) and U.S. Pat. No. 4,661,122 (Lewtas).
Copolymers of dialkyl fumarate-vinyl acetate in which a large proportion of the alkyl groups are C
20
to C
24
alkyl groups are also known to function as dewaxing aids, see e.g., U.S. Pat. Nos. 4,670,130 and 4,956,492 (A. R. Dekraker and D. J. Martella).
The search has therefore continued for improvements to commercially acceptable processes for copolymerization of vinyl acetate and fumaric acid diesters for the production of these fuel and lubricating oil additives which can be conducted in either the presence or absence of a solvent medium.
SUMMARY OF THE INVENTION
A process comprising the copolymerization of:
(a) unsaturated carboxy ester monomer selected from at least one compound represented by formulas (I) or (II), said compound formed via the esterification of an unsaturated carboxylic acid or its corresponding anhydride with one or more monohydric aliphatic alcohols having an average carbon number of between a
Alvarino Ariel
Bloch Ricardo A.
Gardiner James M.
Lapinas Arunas T.
Martella David J.
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