Macromolecular materials

Details Macromolecular materials Macromolecular materials

2001-10-15

2003-01-21

Toomer, Cephia D. (Department: 1714)

Fuel and related compositions

Liquid fuels

Containing organic -c

C044S395000, C524S275000, C508S475000

Reexamination Certificate

active

06508848

ABSTRACT:

This application is a 371 of PCT/EP99/09609, filed Dec. 6, 1999.
This invention relates to additives for use in oil compositions, primarily fuel oil compositions, and more especially fuel oil compositions susceptible to wax formation at low temperatures, and to processes for the manufacture of the additives.
Fuel oils, whether derived from petroleum or from vegetable sources, contain components, e.g., alkanes, that at low temperature tend to precipitate as large crystals or spherulites of wax in such a way as to form a gel structure which causes the fuel to lose its ability to flow. The lowest temperature at which the fuel will still flow is known as the pour point.
As the temperature of the fuel falls and approaches the pour point, difficulties arise in transporting the fuel through lines and pumps. Further, the wax crystals tend to plug fuel lines, screens, and filters at temperatures above the pour point. These problems are well recognized in the art, and various additives have been proposed, many of which are in commercial use, for depressing the pour point of fuel oils. Similarly, other additives have been proposed and are in commercial use for reducing the size and changing the shape of the wax crystals that do form. Smaller size crystals are desirable since they are less likely to clog a filter.
The wax from a diesel fuel, which is primarily an alkane wax, crystallizes as platelets; certain additives inhibit this and cause the wax to adopt an acicular habit, the resulting needles being more likely to pass through a filter than are platelets. The additives may also have the effect of retaining in suspension in the fuel the crystals that have formed, the resulting reduced settling also assisting in prevention of blockages.
Effective wax crystal modification (as measured by cold filter plugging point (CFPP) and other operability tests, as well as simulated and field performance) is achieved by ethylene-vinyl acetate (EVAC) or propionate copolymer-based flow improvers.
It has over a long period—see, for example, U.S. Pat. No. 3,600,311—been proposed to employ hydrogenated diene copolymers, having one or more crystalline, or crystallizable, regions and one or more non-crystallizable regions, as cold flow improvers. These materials are effective wax crystal modifiers, or nucleators, but have the disadvantage that their manufacture, involving a lithium-containing polymerization catalyst, at least two-stage polymerization and subsequent hydrogenation, is expensive.
The present invention provides a macromolecular material of the formula AB, comprising a moiety A having a molecular weight within the range of from 400 to 7000, and containing an alkyl or alkylene chain, and having a linearity such that its degree of crystallinity is at least 25%, and a moiety B imparting oil solubility to the material, moiety B having a degree of crystallinity of at most 10%, the moieties A and B being linked by a bond other than a carbon to carbon bond, or being linked by a functional group, advantageously one that is the reaction product of nucleophilic and electrophilic groups. For simplicity, this material will be referred to below as the macromolecular material of the invention.
The additive composition of this invention comprises the foregoing macromolecular material in combination with a terpolymer of ethylene, vinyl acetate, and a vinyl ester of a C
2
to C
10
alkane carboxylic acid.
In one embodiment of the invention, moiety A is, or comprises, an ethylene-based polymer, either a homopolymer or a copolymer. The polymer may be obtained by polymerization of ethylene, optionally with up to 15, preferably up to 8, and most preferably up to 5, molar percent of one or more ethylenically unsaturated co-monomers, advantageously ethylenically unsaturated hydrocarbons, such as olefins, having from 3 to 16, advantageously from 3 to 8, carbon atoms. Alpha-olefines are preferred, for example propene or a butene.
An ethylene-based moiety A may be prepared, for example, by Ziegler-Natta polymerization, or by metallocene/alumoxane catalysed polymerization, in which case it advantageously contains, before linkage, at least 30%, more advantageously at least 50%, preferably at least 60%, and most preferably 75 to 95%, terminal ethenylidene unsaturation, and is prepared as described in EP-A-353 935, the entire disclosure of which is incorporated herein by reference, as are those of WO 91/11469 and WO 94/13709, the specifications also describing ways in which polymer moiety A may be provided with an electrophilic or nucleophilic group to link it to a moiety B. Alternatively the polymer may be obtained by polymerization using alpha-omega enchainment of a linear diene, especially butadiene, and subsequent hydrogenation. The linear diene may be polymerized alone or with a branched co-monomer, in a manner that provides some alpha-beta enchainment, and hence some branching, provided that the required degree of crystallinity is achieved. Hydrogenated polybutadiene is preferred.
In a further embodiment, moiety A is, or comprises, a wax. Advantageously the wax is one containing a major proportion by weight of n-alkanes, and preferably the n-alkane content is at least 30%. The wax advantageously contains an ethylenically unsaturated group, or some other reactive group, all such groups advantageously being terminal groups.
Alternatively the wax may be used to alkylate a phenol, the hydroxyl group of which forms the link to moiety B.
An advantageous molecular weight range for moiety A is from 1000 to 5000; from 1000 to 3000 is preferred and about 1500 is most preferred. When moiety A is a polymer or a wax, the molecular weight is Mn, as measured by GPC.
The degree of crystallinity of moiety A may be determined by X-ray diffraction and DSC. Advantageously, the degree of crystallinity is at least 30% and is preferably at least 40%.
Turning now to moiety B, this is advantageously a polymeric material, and whether or not it is polymeric advantageously has a molecular weight (Mn in the case of a polymer) within the range of from 1000 to 70,000, more advantageously from 2000 to 20,000, preferably from 2000 to 10,000, and most preferably from 5000 to 6000.
The molecular weights of the two moieties are advantageously of the same order; preferably the molecular weight of the B moiety is from 1 to 5 times that of the A moiety.
Moiety B is advantageously an ethylene-based homo or copolymer. Like moiety A, it may be obtained by polymerization of ethylene, with one or more ethylenically unsaturated, preferably hydrocarbon, comonomers, which is or are present in a proportion, for example at least 20, and preferably at least 30, molar percent, sufficiently high to give a polymer with a sufficiently low crystallinity. Alternatively, it may be an ethylene homopolymer prepared in such a way as to give a high degree of branching, i.e., one having at least 10 CH
3
groups per 100 CH
2
groups. The polymer may be prepared, as described above with reference to moiety A, by for example Ziegler-Natta or metallocene/alumoxane catalysed polymerization.
Polymers based on one or more olefinic hydrocarbon monomers other than ethylene may also be used, especially those containing from 3 to 10, more especially 3 to 5, carbon atoms. Such monomers include for example, propene, n-and iso-butene, 1-pentene, 1-octene, and styrene. Preferred examples of monomers and monomer mixtures are propene, propeneliso-butene, n-butene/iso-butene and, especially, isobutene.
Further, the polymer may be obtained by at least partly 1,2-configuration polymerization of a linear diene, by polymerization of a branched diene, or by a combination of such polymerizations, and subsequent hydrogenation. Suitable dienes include, for example, butadiene, isoprene, and 2,3-dimethylbutadiene. Mixed 1,2 and 1,4 polymerization of butadiene provides on hydrogenation an ethylene-butene type polymer, while isoprene yields an ethylene-propene type material.
Moiety B is advantageously a hydrocarbon polymer, and preferably is predominantly a saturated or unsaturated aliphatic chain. It may,

Affiliated with

Also associated with

Rating

Macromolecular materials does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Macromolecular materials, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Macromolecular materials will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3067551