Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymer of an ethylenically unsaturated reactant with a...
Reexamination Certificate
1998-05-29
2002-09-03
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymer of an ethylenically unsaturated reactant with a...
C526S325000, C526S329000, C526S330000
Reexamination Certificate
active
06444784
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to wax crystal modifiers useful in improving the flow characteristics of lube oils and waxy crudes.
BACKGROUND
Many oils, especially crude oils, contain straight chain and branched alkanes that crystallize as their temperature is lowered. Alkane (wax) crystallization in these oils results in increased viscosity which leads to problems such as pipelining difficulties in crudes. The temperature at which wax begins to crystallize in an oil is called the wax appearance temperature (WAT) of the oil. Polymeric and copolymeric compounds can be combined with an oil in order to reduce an oil's WAT. Such additives, known as wax crystal modifiers, can be used as flow improvers in lubricating oils.
Lubricating oils and crude oils have quite different compositions. For example, crude oils contain inorganics, resins, and asphaltenes that are not present in lubricating oils beyond trace levels. Crude oils also contain hydrocarbons having a wider range of molecular weights. These factors contribute to a higher WAT than in lubricating oils. Crude oil WATs can range from about −15° C. to about 30° C., compared to a range of about −25° C. to about −5° C. for lubricating oils.
Dialkyl fumarate-vinyl acetate (DAF-VA) copolymers are used as lubricating oil flow improvers. These copolymers may be formed by the free radical polymerization of vinyl acetate and DAF esters having alkyls ranging in size from about 10 to about 18 carbon atoms. Such copolymers are effective lubricating oil flow improvers at temperatures ranging from about −25° C. to about −5°° C. Such flow improvers are not expected to be effective for crude oils because crude oil WATs are generally outside this temperature range.
There remains a need for polymers and copolymers useful for improving the flow properties of oils, and especially polymers and copolymers capable of improving the flow properties and pipelinability of crude oils.
SUMMARY OF THE INVENTION
In one embodiment, the invention is a copolymer of carbon monoxide and C
6
to C
250
straight-chain or branched dialkyl fumarate.
In another embodiment, the invention is a flow improver for use in an oleaginous fluid comprising one or more copolymers of dialkyl fumarate wherein the alkyl is straight chain or branched and ranges in size from C
6
to C
250
and carbon monoxide.
In another embodiment, the invention is a crude oil wax crystal modifier comprising a copolymer of dialkyl fumarate having straight chain or branched alkyls ranging in size from about C
6
to about C
250
and at least one compound selected from the group consisting of C
3
to C
30
alpha olefin, ethylene, styrene, carbon monoxide, and vinyl acetate.
In another embodiment, the invention is a method for improving the flow properties in an oleagenous fluid comprising: adding to a major amount of the oleagenous fluid a minor amount of at least one copolymer of dialkyl-fumarate having C
6
to C
250
straight chain or branched alkyls and at least one compound selected from the group consisting of C
3
to C
30
alpha olefin, ethylene, styrene, and carbon monoxide, provided that when the oleagenous fluid is a lubricating oil or a distillate oil that the compound is carbon monoxide.
In another embodiment, the invention is a method for forming a copolymer comprising:
dissolving a C
6
to C
250
straight-chain dialkyl fumarate in a solvent selected from the group consisting of hexane, benzene, cyclohexane, chloroform, xylene, oil, and heptane;
combining the dissolved dialkyl fumarate and an initiator selected from the group consisting of t-butyl peroxypivalate, benzoyl peroxide, t-butylper benzoate, and t-butyl peroxide in a reactor;
sealing the reactor and then purging the reactor with purified nitrogen;
pressurizing the reactor with at least one compound selected from the group consisting of carbon monoxide and ethylene to a pressure ranging from about 100 to about 3000 psig; and
heating the reactor to a temperature ranging from about 40° C. to about 200° C. for a time ranging from about 1 hour to about 48 hours in order to form the copolymer.
In another embodiment, the invention is a method for forming a copolymer comprising:
combining under free radical polymerization conditions a C
6
to C
250
straight-chain dialkyl fumarate in a solvent selected from the group consisting of hexane, benzene, cyclohexane, chloroform, xylene, oil, and heptane; at least one compound selected from the group consisting of ethylene and carbon monoxide; and an initiator selected from the group consisting of t-butyl peroxypivalate, benzoyl peroxide, t-butylper benzoate, and t-butyl peroxide, for a time, temperature, and pressure sufficient to form the copolymer.
In another embodiment, the invention is a method for improving the flow properties in an oleagenous fluid having at least one alkane species comprising:
determining a molecular weight distribution of the alkane species in the oleagenous fluid and then
adding to a major amount of the oleagenous fluid a minor amount of at least one copolymer of dialkylfumarate having straight chain or branched alkyls having substantially the same molecular weight distribution and at least one compound selected from the group consisting of C
3
to C
30
alpha olefin, ethylene, styrene, and carbon monoxide.
DETAILED DESCRIPTION OF THE INVENTION
The invention is based on the discovery that dialkylfumarate-containing copolymers having straight chain or branched alkyls ranging in size from about C
6
to about C
250
are effective flow improvers in oleaginous fluids such as fuel oils, lubricating oils, and crude oils. The invention is also based on the discovery that dialkylfumarate can be copolymerized with carbon monoxide.
Copolymers of the present invention having the formula:
wherein B is formed from compounds selected from the group consisting of carbon monoxide, vinyl acetate, styrene, ethylene, and C
3
to C
30
alpha olefin and wherein R is branched or straight chain alkyl ranging from C
6
to C
250
are prepared as follows.
Dialkylfumarate esters having alkyls ranging up to C
250
are prepared by diesterification of fumaric acid with aliphatic alcohols in the presence of a p-toluene sulfonic acid catalyst. Alternatively, the esters can be prepared from fumaryl chloride and alkyl alcohols using an amine catalyst.
Comonomer B is formed from at least one compound selected from the group consisting of vinyl acetate, styrene, C
3
to C
30
&agr;-olefin, ethylene, and carbon monoxide. The term copolymer is thus used in accordance with its more general meaning where the polymer comprises two or more different monomers.
R represents independently selected straight chain or branched alkyl groups of from about C
6
to about C
250
carbon atoms. Preferred alkyls range from about C8 to about C
40
.
The copolymers of this invention can be synthesized using free-radical polymerization. In the case of copolymers of dialkyl fumarate with monomers like vinyl acetate, styrene or C
3
to C
30
&agr;-olefins, polymerization can be carried out in a standard glass reactor. Typically, any inhibitors present in the monomers are removed via an inhibitor remover column. The purified monomers are then placed in tubes with the DAF ester monomers. The tubes are capped with septa and flushed with nitrogen for one to four hours before polymerization. The composition of monomers can be varied from about 5:95 to about 95:5 mole percent.
The reactions can be carried out in a solvent or neat. When a solvent is used, the solvent should be nonreactive or noninterfering in free radical polymerization. Such solvents include benzene, cyclohexane, hexane, heptane, etc. Solvents like xylene or oil can also be used. The solvent may be flushed with argon or nitrogen and then added to the monomers.
The polymerization reactions can be carried out from 40 to 100° C. depending on reactivity of monomers, half-life of the initiator used, or the boiling point of the solvent. The reactions are carried out under inert atmosphere. The solvents are brought to the reac
Berluche Enock
Patil Abhimanyu Onkar
Varma-Nair Manika
Zushma Stephen
Boykin Terressa M.
ExxonMobil Research & Engineering Company
Hughes Gerard J.
Wang Joseph C.
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