POUR POINT DEPRESSION
United States Patent 3803034
Hydrocarbon oil which loses fluidity at low temperature containing, in a pour point depressant concentration, a terpolymer of C2 -C22 -olefin, aryl-C2 -C22 -alkylene and unsaturated ester. Specific pour point depressants are terpolymer of ethylene-styrene-methylmethacrylate or terpolymer of ethylene-styrene-vinyl acetate.
US Patent References:
FUEL OIL COMPOSITIONS CONTAINING GRAFTED POLYMERS
Tunkel - August 1969 - 3462249
FUEL OIL COMPOSITIONS CONTAINING GRAFTED POLYMERS
Tunkel - August 1969 - 3462249
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Application Number:
05/286651
Publication Date:
04/09/1974
Filing Date:
09/05/1972
Export Citation:
Assignee:
Universal Oil Products Company (Des Plaines, IL)
Primary Class:
Other Classes:
44/396
International Classes:
C10L1/18; C10L1/195; C10M145/08; C10M145/14; C10L1/10; C10M145/00; C10M1/28; C10M1/26
Field of Search:
252/56R,57 44/62 208/33,38
Primary Examiner:
Cannon W.
Assistant Examiner:
Cannon W.
Attorney, Agent or Firm:
Hoatson Jr. II, James Kramer Bernard Page William R. L. H.
Claims:
1. Hydrocarbon oil containing components which cause the oil to lose fluidity at low temperature, said oil containing, in a pour point depressant concentration, a terpolymer of from about 5 to 30 mole proportions of ethylene, from about 0.5 to 5 mole proportions of styrene and from about 0.5 to 5 mole proportions of methylmethacrylate, said interpolymer having a molecular weight of from about 500 to about 5,000.
2. The hydrocarbon oil of claim 1 being middle distillate within the
3. The hydrocarbon oil of claim 1 being residual oil having an initial
4. The composition of claim 1 further characterized in that the styrene and methylmethacrylate are in equimolar proportion and the ratio of the ethylene to the total styrene and methylmethacrylate reactants is about 10:1, the average molecular weight of the interpolymer being about 2,800.
2. The hydrocarbon oil of claim 1 being middle distillate within the
3. The hydrocarbon oil of claim 1 being residual oil having an initial
4. The composition of claim 1 further characterized in that the styrene and methylmethacrylate are in equimolar proportion and the ratio of the ethylene to the total styrene and methylmethacrylate reactants is about 10:1, the average molecular weight of the interpolymer being about 2,800.
Description:
BACKGROUND OF THE INVENTION
The problems associated with the loss of fluidity of hydrocarbon oils at low temperatures are of considerable concern. Such loss of fluidity interferes with the satisfactory storing and transporting of the oil, as well as in mixing or blending of different oil fractions and in filtering operations. This problem is of increasing concern with the discovery of oil in subarctic areas, with the use of jet fuels at altitudes where temperatures of -50° F. or lower may be encountered, etc.
Such hydrocarbon oils are sometimes referred to as heavier oils and contain components which, upon encountering low temperatures, crystallize to form solid precipitates. These crystals become active centers for further crystallization, with the result that the oil congeals and loses its free flowing properties. The oils are of diversified chemical composition and many of the heavier oils contain waxy components in varying concentrations. These waxy components crystallize readily at low temperatures. Because of the variations in chemical compositions, different oils respond differently to pour point depressant additives. Accordingly, there is a need for novel pour point depressants which will serve to improve the flowing properties of the oils at low temperatures.
DESCRIPTION OF THE INVENTION
The present invention is directed to novel terpolymers for use as pour point depressants in such oils. The oils may be classified as those having pour points of above about -20° F. The oil may have an initial boiling point as low as 175° F. and end boiling point of above 1,000° F. under vacuum or practically not distillable but, as hereinbefore set forth, contains components which are responsible for the loss of fluidity. Illustrative examples of such oils include middle distillates, specialty oils, lubricating oils, residual oils, crude oils, etc. These oils may be untreated or resulting from conventional fractionation, solvent extraction, caustic treating, acid treating, dewaxing, desulfurizing, thermal cracking, catalytic cracking, reforming or other processing operations, etc. The middle distillates include oils within the boiling range of from about 250° to 750° F. and include kerosene, jet fuel, diesel oil, burner oil, gas oil, fuel oil, light cycle oil, specialty oils such as solvent oils, cleaning oils for use in cleaning metallic equipment, electrical insulating oil which is used in transformers or circuit breakers, hydraulic oils, etc. The lubricating oils may be conventional lubricating oils having boiling points, for example, within the range of 650° to 1,050° F. or more or selected fractions thereof for special uses. The residual oils may result from fractionation to remove lower boiling components or heavier oils resulting from processing operations and may have initial boiling points of 600° F. or more. As mentioned earlier, problems are encountered in the transportation and storage of crude oils and reduced crude oils at low temperatures and especially in cold climates.
In one embodiment, the present invention relates to a hydrocarbon oil containing components which cause the oil to lose fluidity at low temperature, said oil containing, in a pour point depressant concentration, a terpolymer of C 2 -C 22 -olefin, aryl-C 2 -C 22 -alkylene and unsaturated ester of the formula: ##SPC1##
in which R is hydrogen or C 1 -C 6 -alkyl and R' is C 1 -C 22 -alkyl.
The terpolymer embraced in the above definition is believed to comprise a new composition of matter. The composition may also contain all or a portion of a free radical initiator and particularly organic peroxide used in the preparation of the terpolymer, as well as some of the solvent, when employed which is not subsequently removed from the composition. However, the initiator, if present, will be in a minor concentration and the solvent probably is present in a chemically uncombined state. Such retained solvent will increase solubility of the terpolymer and, as will be hereinafter set forth, the terpolymer may be commingled with additional solvent to form a fluid concentrate for use as a pour point depressant.
As hereinbefore set forth, one component of the terpolymer is a C 2 -C 22 -olefin and preferably a C 2 -C 6 -olefin. In one embodiment, ethylene is a particularly preferred olefin. Other preferred olefins include propylene, butylene, amylene and hexylene. Other olefins comprise heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octadecylene, nonadecylene, eicosylene, heneicosylene, docosylene. It is understood that the olefin may be of straight or branched chain, with the double bond preferably in a terminal position. With two double bonds, they may be conjugated or randomly located in such a manner that one double bond is in a terminal position.
Another component of the terpolymer is an aryl-C 6 -C 22 -alkylene and preferably a phenyl-C 2 -C 6 -alkylene which also may be named as an alkenyl aromatic. In a particularly preferred embodiment, the double bond of the alkylene moiety is positioned between the alpha and beta carbon atoms and thus is in close proximity to the aromatic ring. In this embodiment, styrene is an especially preferred alkenyl aromatic. Other preferred alkenyl aromatics contain up to 6 carbon atoms in the alkenyl moiety and include alpha-methylstyrene, alpha-ethylstyrene, alpha-propylstyrene, and alpha-butylstyrene. In another embodiment, but not necessarily with equivalent results, the alkylene moiety may contain from 7 to 22 carbon atoms and may contain two or more double bonds therein, with a double bond in a terminal position and a terminal carbon atom attached to two hydrogen atoms. Such higher boiling olefinic moieties may be separated as specific fractions from particular processing steps or may be prepared by polymerization of olefinic and/or diolefinic C 2 -C 6 -olefins. The phenyl alkylene may be prepared by conventional alkylation of benzene with the olefin or in any other suitable manner. In still another embodiment instead of the phenyl alkylene, other vinyl aromatics may be used as vinyl naphthalene, alpha-methyl-vinyl naphthalene, etc., but not necessarily with equivalent results.
In another embodiment, the aryl alkylene may contain one or more substituents attached to the aryl ring. These substituents may be selected from alkyl of 1 to 12 carbon atoms, alkoxy containing from 1 to 12 carbon atoms in the alkyl moiety, phenoxy, hydroxy, halogen and preferably chlorine or bromine, etc. In a preferred embodiment, only one such substituent is attached to the phenyl ring and preferably in a position para to the alkylene moiety. When two substituents are attached to the phenyl ring, they preferably are in the 3,4- or 3,5- positions.
Another component of the terpolymer is an unsaturated ester of the formulas hereinbefore set forth. The formula I, to the left, illustrates esters which may be generically termed alkylcarboxyethylenes or vinylic alkanoates. Illustrative examples include vinyl acetate, vinyl propionate, vinyl butyrate, preferably vinyl isobutyrate, vinyl valerate, vinyl hexanoate, vinyl heptanoate, vinyl caprylate, vinyl nonanoate, vinyl decanoate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, etc. When R is alkyl, illustrative compounds comprise isopropenyl acetate, 1-ethylvinyl acetate, 1-propylvinyl acetate, 1-butylvinyl acetate, etc., and corresponding higher molecular weight alkanoates.
Referring to the formulas hereinbefore set forth, formula II, to the right, illustrates alkylcarboxyethylenes, carbalkoxyethylenes or derivatives of acrylic acid. Illustrative examples include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, capryl acrylate, lauryl acrylate, myristyl acrylate, palmityl acrylate, stearyl acrylate, etc. When R is methyl, the corresponding methacrylates will comprise a component of the terpolymer. Methylmethacrylate, ethylmethacrylate, propylmethacrylate and butylmethacrylate are particularly preferred in this embodiment.
It is understood that the various olefins, phenyl alkylenes and unsaturated esters are not necessarily equivalent for use in preparation of the terpolymers. These components will be selected with reference to the particular terpolymer to be prepared which, in turn, will depend upon the particular oil in which it is to be used. In another embodiment, an unsaturated ester of formula I and an unsaturated ester of formula II are both used in preparing a tetrapolymer. As hereinbefore set forth, different oils respond differently to additives. Also, the particular components will be selected with regard to availability, cost and reactivity in forming the desired terpolymer.
The terpolymer is prepared in any suitable manner. In one embodiment, the terpolymer is produced by polymerization using conventional initiators of the free radical type such as benzoyl peroxide, tert-butyl peroxide, di-tert-butyl peroxide, cumene peroxide, 2,2'-azobisbutyronitrile, etc. The peroxide generally is used in a concentration of from about 0.1% to 10% and preferably 1-2% by weight of the liquid monomers. Conveniently, a typical hydrocarbon polymerization solvent is used, as for example, benzene, toluene, xylene, aromatic commercial solvents such as Espesol, alcohols, ketones, esters, halogenated hydrocarbons, etc. The temperature of polymerization is generally within the range of from about 150° to about 350° F. and preferably from about 275° to about 325° F. The pressure may be within the range of from about 500 to 2,000 or more and preferably 800 to 1,500 lbs. per sq. in. The time of reaction will be sufficient to accomplish the desired polymerization and may range from 1 to 12 hours or more and preferably 2 to 6 hours.
In one specific method of preparation of the terpolymer, utilizing a rotating autoclave as the reaction zone, the autoclave is first purged with nitrogen and then charged with a solution of methylmethacrylate in benzene, a solution of styrene in benzene and a solution of tertiary butyl peroxide in benzene. The autoclave then is closed tightly, purged with ethylene, vented and pressurized with ethylene to the desired pressure, heated to the desired temperature and maintained therein for the desired time. In some cases, purging of the autoclave may be omitted and the polymerization effected in the presence of a small amount of air.
Following completion of the reaction, the autoclave is allowed to cool and the products withdrawn, filtered and evaporated, preferably under vacuum, to remove solvent and to recover the terpolymer. It is understood that this is a preferred method of preparing the terpolymer batchwise when using the peroxide type initiator and that other suitable methods may be employed. In another embodiment, preparation of the terpolymer is effected in a continuous manner. In this embodiment, the reaction chamber is maintained at the desired temperature and contains some form of packing, such as glass beads, berl saddles, raschig rings, etc. In one method, a solution of the phenyl alkylene, unsaturated ester and peroxide initiator is prepared and charged to the reaction chamber, with ethylene under high pressure being separately charged to the reaction chamber. In one method, the solution and ethylene may be passed concurrently but preferably are passed countercurrently into the reaction chamber. For example, the solution may be introduced into an upper portion of the reaction chamber and the ethylene is introduced into a lower portion thereof. In still another method, the phenyl alkylene, unsaturated ester and/or peroxide catalyst may be introduced separately into the reaction chamber. Regardless of the specific method employed, excess ethylene is withdrawn, preferably from an upper portion of the reaction chamber, and reused in the process. The liquid effluent from the reaction chamber is withdrawn, preferably from a lower portion thereof, and is processed in any suitable manner to recover the terpolymer, preferably by filtering and then vacuum distillation to remove the solvent. In another embodiment, metal oxides or other initiators of free radicals for promoting polymerization may be used.
The reactants are used in any suitable proportions. In general the olefin, and particularly ethylene, will be used in a large overall proportion. Overall means the amount of ethylene totally present in gaseous and liquid phase within the system. Since the critical temperature of ethylene is only 50° F., the ethylene will be in gaseous state under the conditions of copolymerization. Only a small part of the ethylene will be dissolved in the liquid phase. It was found that, with an overall excess of 100 to 300:1, only 4 to 20:1 mole ratio of ethylene to other monomers was actually present in the liquid reaction mixture, i.e. in the monomers and initiator in the solvent. The amount of ethylene dissolved in the liquid phase depends on the nature and amount of the solvent, temperature and pressure of ethylene. The mole ratios in the terpolymer may comprise from 5 to 30 and preferably 10 to 25 mole proportions of ethylene, from about 0.5 to 5 and preferably 1 to 3 mole proportions of styrene and from about 0.5 to 5 and preferably 1 to 3 mole proportions of unsaturated ester. The molecular weight of the terpolymer may range from about 500 to 5,000 or more and preferably from about 1,000 to about 3,000 and more particularly from about 1,500 to about 2,500.
In one embodiment, all or a major portion of the solvent is removed from the product and the terpolymer is recovered as a solid material. In another embodiment, at least a substantial portion of the solvent is allowed to remain and the terpolymer is recovered as a concentrated solution for use as a concentrate to be incorporated as a pour point depressant in the oil. In still another embodiment, other solvents may be used to comprise a more homogeneous solution for use as a pour point depressant.
As hereinbefore set forth, the novel terpolymer of the present invention is a very effective pour point depressant. It is believed that the phenyl moiety being attached to the main polymeric chain forms an improved pour point depressant of increased solubility as compared, for example, to copolymers of olefin and unsaturated ester.
The chemical structure of the copolymer can vary, depending upon the specific character of the reactants, and mode of preparation. It may form a polyethylenic straight chain to which phenyl and polar alkyls are attached and some incidental alkyls resulting from some branching and chain termination mode. Also, as hereinbefore set forth, a small amount of the peroxide catalyst may enter into the reaction, as well as the final composition containing some unremoved solvent. Regardless of the specific chemical structure, the terpolymer, prepared as described herein, is a very effective pour point depressant. As another advantage to the present invention, the terpolymer is useful in many different oils and thus extends the range of its applicability.
The terpolymer is incorporated in the oil in a sufficient concentration to lower the pour point of the oil to a satisfactory degree. For economical reasons, the additive is used in as low a concentration as is satisfactory for the purpose and may be within the range of from about 0.001% to about 1% but generally is within the range of from about 0.005% to about 0.1% by weight of the oil. It is understood that the pour point depressant may be used in conjunction with other additives normally incorporated in the hydrocarbon oil, which will vary with the particular hydrocarbon oil and may comprise one or more of anti-oxidant, corrosion or rust inhibitor, viscosity index improver, cetane improver, metal deactivator, dye, etc.
The following examples are introduced to illustrate further the novelty and utility of the present invention but not with the intention of unduly limiting the same.
EXAMPLE I
This example describes the preparation of a terpolymer of ethylene, styrene and methylmethacrylate. The preparation was made in a 3 liter rotating autoclave which first was purged with nitrogen and then charged with 5 g. (0.05 mole) methylmethacrylate in 100 g. of benzene, 5.02 g. (0.05 mole) of styrene in 100 g. of benzene and 1 g. (0.007 mole) of tert-butyl peroxide in 100 g. of benzene. The autoclave was sealed tight and purged with ethylene at a pressure of about 70 atmospheres, and then vented. The autoclave next was pressured to 70 atmospheres with ethylene, thus saturating the reaction mixture, heated to 284° F. and maintained at this temperature for 4 hours, after which the autoclave was cooled and 296 g. of liquid product recovered. The liquid product was warmed, filtered, and evaporated (20 torr.) to yield 25 g. of tacky solid. The styrene to methylmethacrylate ratio in the terpolymer is 1:1 and the ratio of ethylene to the total of other reactants is 10.4:1. The average molecular weight of the terpolymer is 2,800.
EXAMPLE II
Another terpolymer preparation was made in substantially the same manner as described in Example I except that the solvent used in this preparation was toluene. Specifically, the rotating autoclave was charged with 5 g. (0.05 mole) of methylmethacrylate in 100 g. of toluene, 5.02 g. (0.05 mole) of styrene in 100 g. of toluene and 1 g. (0.007 mole) of tert-butyl peroxide in 100 g. of toluene. Following purging and pressurizing to 70 atmospheres with ethylene, the autoclave was heated and maintained at 284° F. for 4 hours. After cooling, 308 g. of liquid was withdrawn from the autoclave, filtered and evaporated to remove solvent, to yield 14 g. of soft and tacky dry solid product. The average molecular weight of the terpolymer is 1180.
EXAMPLE III
A terpolymer is prepared in substantially the same manner as described in Example I except that the unsaturated ester is vinyl acetate. The reactants are charged to the rotating autoclave in mole ratios of ethylene:styrene:vinyl acetate of 15:1.5:1. Following completion of the reaction and removal of the benzene solvent, the product is recovered as a solid terpolymer.
EXAMPLE IV
Another terpolymer is prepared in substantially the same manner as described in Example II except that alpha-methylstyrene is used as the phenyl alkylene. The reactants are used in a mole ratio of ethylene:transbeta-methylstyrene:methylmethacrylate of 12:1:1.5. After cooling of the autoclave, filtering and vacuum distillation to remove the solvent, the solid terpolymer product is recovered.
EXAMPLE V
Another preparation is made in the same manner as described in Example II except that vacuum distillation to remove the toluene solvent is omitted and the resultant solution is utilized as a liquid concentrate for adding as a pour point depressant to a hydrocarbon oil.
EXAMPLE VI
The terpolymer prepared as described in Example I was utilized as a pour point depressant in a commercial light cycle oil having a pour point of -2° F. and a boiling range of 358°-709° F. The terpolymer was evaluated at different concentrations, based on active ingredient, ranging from a high of 500 ppm (parts per million) down to a low of 10 ppm. The data was reported in the following table.
TABLE I ______________________________________ Additive Pour Point Concentration Pour Point Depression ppm °F. °F. ______________________________________ None -2 - 500 <-60 >-60 50 -43 >41 25 -25 23 10 -20 18 ______________________________________
From the data in the above table, it will be seen that the terpolymer was very effective in lowering the pour point of the oil. Even in a concentration as low as 10 ppm, the pour point was lowered from -2° to -20° F.
EXAMPLE VII
The terpolymer prepared as described in Example II is used in a concentration of 250 ppm in a commercial No. 2 fuel oil having a boiling range of 428°-677° F. and a pour point of 10° F. The addition of the terpolymer serves to decrease the pour point to -20° F.
EXAMPLE VIII
The flowing properties of crude oil in subarctic areas is improved by incorporating therein 250 ppm of the terpolymer prepared as described in Example I.
EXAMPLE IX
The pour point properties of lubricating oil are improved by incorporating therein 1,000 ppm of the terpolymer prepared as described in Example II.
The problems associated with the loss of fluidity of hydrocarbon oils at low temperatures are of considerable concern. Such loss of fluidity interferes with the satisfactory storing and transporting of the oil, as well as in mixing or blending of different oil fractions and in filtering operations. This problem is of increasing concern with the discovery of oil in subarctic areas, with the use of jet fuels at altitudes where temperatures of -50° F. or lower may be encountered, etc.
Such hydrocarbon oils are sometimes referred to as heavier oils and contain components which, upon encountering low temperatures, crystallize to form solid precipitates. These crystals become active centers for further crystallization, with the result that the oil congeals and loses its free flowing properties. The oils are of diversified chemical composition and many of the heavier oils contain waxy components in varying concentrations. These waxy components crystallize readily at low temperatures. Because of the variations in chemical compositions, different oils respond differently to pour point depressant additives. Accordingly, there is a need for novel pour point depressants which will serve to improve the flowing properties of the oils at low temperatures.
DESCRIPTION OF THE INVENTION
The present invention is directed to novel terpolymers for use as pour point depressants in such oils. The oils may be classified as those having pour points of above about -20° F. The oil may have an initial boiling point as low as 175° F. and end boiling point of above 1,000° F. under vacuum or practically not distillable but, as hereinbefore set forth, contains components which are responsible for the loss of fluidity. Illustrative examples of such oils include middle distillates, specialty oils, lubricating oils, residual oils, crude oils, etc. These oils may be untreated or resulting from conventional fractionation, solvent extraction, caustic treating, acid treating, dewaxing, desulfurizing, thermal cracking, catalytic cracking, reforming or other processing operations, etc. The middle distillates include oils within the boiling range of from about 250° to 750° F. and include kerosene, jet fuel, diesel oil, burner oil, gas oil, fuel oil, light cycle oil, specialty oils such as solvent oils, cleaning oils for use in cleaning metallic equipment, electrical insulating oil which is used in transformers or circuit breakers, hydraulic oils, etc. The lubricating oils may be conventional lubricating oils having boiling points, for example, within the range of 650° to 1,050° F. or more or selected fractions thereof for special uses. The residual oils may result from fractionation to remove lower boiling components or heavier oils resulting from processing operations and may have initial boiling points of 600° F. or more. As mentioned earlier, problems are encountered in the transportation and storage of crude oils and reduced crude oils at low temperatures and especially in cold climates.
In one embodiment, the present invention relates to a hydrocarbon oil containing components which cause the oil to lose fluidity at low temperature, said oil containing, in a pour point depressant concentration, a terpolymer of C 2 -C 22 -olefin, aryl-C 2 -C 22 -alkylene and unsaturated ester of the formula: ##SPC1##
in which R is hydrogen or C 1 -C 6 -alkyl and R' is C 1 -C 22 -alkyl.
The terpolymer embraced in the above definition is believed to comprise a new composition of matter. The composition may also contain all or a portion of a free radical initiator and particularly organic peroxide used in the preparation of the terpolymer, as well as some of the solvent, when employed which is not subsequently removed from the composition. However, the initiator, if present, will be in a minor concentration and the solvent probably is present in a chemically uncombined state. Such retained solvent will increase solubility of the terpolymer and, as will be hereinafter set forth, the terpolymer may be commingled with additional solvent to form a fluid concentrate for use as a pour point depressant.
As hereinbefore set forth, one component of the terpolymer is a C 2 -C 22 -olefin and preferably a C 2 -C 6 -olefin. In one embodiment, ethylene is a particularly preferred olefin. Other preferred olefins include propylene, butylene, amylene and hexylene. Other olefins comprise heptylene, octylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octadecylene, nonadecylene, eicosylene, heneicosylene, docosylene. It is understood that the olefin may be of straight or branched chain, with the double bond preferably in a terminal position. With two double bonds, they may be conjugated or randomly located in such a manner that one double bond is in a terminal position.
Another component of the terpolymer is an aryl-C 6 -C 22 -alkylene and preferably a phenyl-C 2 -C 6 -alkylene which also may be named as an alkenyl aromatic. In a particularly preferred embodiment, the double bond of the alkylene moiety is positioned between the alpha and beta carbon atoms and thus is in close proximity to the aromatic ring. In this embodiment, styrene is an especially preferred alkenyl aromatic. Other preferred alkenyl aromatics contain up to 6 carbon atoms in the alkenyl moiety and include alpha-methylstyrene, alpha-ethylstyrene, alpha-propylstyrene, and alpha-butylstyrene. In another embodiment, but not necessarily with equivalent results, the alkylene moiety may contain from 7 to 22 carbon atoms and may contain two or more double bonds therein, with a double bond in a terminal position and a terminal carbon atom attached to two hydrogen atoms. Such higher boiling olefinic moieties may be separated as specific fractions from particular processing steps or may be prepared by polymerization of olefinic and/or diolefinic C 2 -C 6 -olefins. The phenyl alkylene may be prepared by conventional alkylation of benzene with the olefin or in any other suitable manner. In still another embodiment instead of the phenyl alkylene, other vinyl aromatics may be used as vinyl naphthalene, alpha-methyl-vinyl naphthalene, etc., but not necessarily with equivalent results.
In another embodiment, the aryl alkylene may contain one or more substituents attached to the aryl ring. These substituents may be selected from alkyl of 1 to 12 carbon atoms, alkoxy containing from 1 to 12 carbon atoms in the alkyl moiety, phenoxy, hydroxy, halogen and preferably chlorine or bromine, etc. In a preferred embodiment, only one such substituent is attached to the phenyl ring and preferably in a position para to the alkylene moiety. When two substituents are attached to the phenyl ring, they preferably are in the 3,4- or 3,5- positions.
Another component of the terpolymer is an unsaturated ester of the formulas hereinbefore set forth. The formula I, to the left, illustrates esters which may be generically termed alkylcarboxyethylenes or vinylic alkanoates. Illustrative examples include vinyl acetate, vinyl propionate, vinyl butyrate, preferably vinyl isobutyrate, vinyl valerate, vinyl hexanoate, vinyl heptanoate, vinyl caprylate, vinyl nonanoate, vinyl decanoate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, etc. When R is alkyl, illustrative compounds comprise isopropenyl acetate, 1-ethylvinyl acetate, 1-propylvinyl acetate, 1-butylvinyl acetate, etc., and corresponding higher molecular weight alkanoates.
Referring to the formulas hereinbefore set forth, formula II, to the right, illustrates alkylcarboxyethylenes, carbalkoxyethylenes or derivatives of acrylic acid. Illustrative examples include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, capryl acrylate, lauryl acrylate, myristyl acrylate, palmityl acrylate, stearyl acrylate, etc. When R is methyl, the corresponding methacrylates will comprise a component of the terpolymer. Methylmethacrylate, ethylmethacrylate, propylmethacrylate and butylmethacrylate are particularly preferred in this embodiment.
It is understood that the various olefins, phenyl alkylenes and unsaturated esters are not necessarily equivalent for use in preparation of the terpolymers. These components will be selected with reference to the particular terpolymer to be prepared which, in turn, will depend upon the particular oil in which it is to be used. In another embodiment, an unsaturated ester of formula I and an unsaturated ester of formula II are both used in preparing a tetrapolymer. As hereinbefore set forth, different oils respond differently to additives. Also, the particular components will be selected with regard to availability, cost and reactivity in forming the desired terpolymer.
The terpolymer is prepared in any suitable manner. In one embodiment, the terpolymer is produced by polymerization using conventional initiators of the free radical type such as benzoyl peroxide, tert-butyl peroxide, di-tert-butyl peroxide, cumene peroxide, 2,2'-azobisbutyronitrile, etc. The peroxide generally is used in a concentration of from about 0.1% to 10% and preferably 1-2% by weight of the liquid monomers. Conveniently, a typical hydrocarbon polymerization solvent is used, as for example, benzene, toluene, xylene, aromatic commercial solvents such as Espesol, alcohols, ketones, esters, halogenated hydrocarbons, etc. The temperature of polymerization is generally within the range of from about 150° to about 350° F. and preferably from about 275° to about 325° F. The pressure may be within the range of from about 500 to 2,000 or more and preferably 800 to 1,500 lbs. per sq. in. The time of reaction will be sufficient to accomplish the desired polymerization and may range from 1 to 12 hours or more and preferably 2 to 6 hours.
In one specific method of preparation of the terpolymer, utilizing a rotating autoclave as the reaction zone, the autoclave is first purged with nitrogen and then charged with a solution of methylmethacrylate in benzene, a solution of styrene in benzene and a solution of tertiary butyl peroxide in benzene. The autoclave then is closed tightly, purged with ethylene, vented and pressurized with ethylene to the desired pressure, heated to the desired temperature and maintained therein for the desired time. In some cases, purging of the autoclave may be omitted and the polymerization effected in the presence of a small amount of air.
Following completion of the reaction, the autoclave is allowed to cool and the products withdrawn, filtered and evaporated, preferably under vacuum, to remove solvent and to recover the terpolymer. It is understood that this is a preferred method of preparing the terpolymer batchwise when using the peroxide type initiator and that other suitable methods may be employed. In another embodiment, preparation of the terpolymer is effected in a continuous manner. In this embodiment, the reaction chamber is maintained at the desired temperature and contains some form of packing, such as glass beads, berl saddles, raschig rings, etc. In one method, a solution of the phenyl alkylene, unsaturated ester and peroxide initiator is prepared and charged to the reaction chamber, with ethylene under high pressure being separately charged to the reaction chamber. In one method, the solution and ethylene may be passed concurrently but preferably are passed countercurrently into the reaction chamber. For example, the solution may be introduced into an upper portion of the reaction chamber and the ethylene is introduced into a lower portion thereof. In still another method, the phenyl alkylene, unsaturated ester and/or peroxide catalyst may be introduced separately into the reaction chamber. Regardless of the specific method employed, excess ethylene is withdrawn, preferably from an upper portion of the reaction chamber, and reused in the process. The liquid effluent from the reaction chamber is withdrawn, preferably from a lower portion thereof, and is processed in any suitable manner to recover the terpolymer, preferably by filtering and then vacuum distillation to remove the solvent. In another embodiment, metal oxides or other initiators of free radicals for promoting polymerization may be used.
The reactants are used in any suitable proportions. In general the olefin, and particularly ethylene, will be used in a large overall proportion. Overall means the amount of ethylene totally present in gaseous and liquid phase within the system. Since the critical temperature of ethylene is only 50° F., the ethylene will be in gaseous state under the conditions of copolymerization. Only a small part of the ethylene will be dissolved in the liquid phase. It was found that, with an overall excess of 100 to 300:1, only 4 to 20:1 mole ratio of ethylene to other monomers was actually present in the liquid reaction mixture, i.e. in the monomers and initiator in the solvent. The amount of ethylene dissolved in the liquid phase depends on the nature and amount of the solvent, temperature and pressure of ethylene. The mole ratios in the terpolymer may comprise from 5 to 30 and preferably 10 to 25 mole proportions of ethylene, from about 0.5 to 5 and preferably 1 to 3 mole proportions of styrene and from about 0.5 to 5 and preferably 1 to 3 mole proportions of unsaturated ester. The molecular weight of the terpolymer may range from about 500 to 5,000 or more and preferably from about 1,000 to about 3,000 and more particularly from about 1,500 to about 2,500.
In one embodiment, all or a major portion of the solvent is removed from the product and the terpolymer is recovered as a solid material. In another embodiment, at least a substantial portion of the solvent is allowed to remain and the terpolymer is recovered as a concentrated solution for use as a concentrate to be incorporated as a pour point depressant in the oil. In still another embodiment, other solvents may be used to comprise a more homogeneous solution for use as a pour point depressant.
As hereinbefore set forth, the novel terpolymer of the present invention is a very effective pour point depressant. It is believed that the phenyl moiety being attached to the main polymeric chain forms an improved pour point depressant of increased solubility as compared, for example, to copolymers of olefin and unsaturated ester.
The chemical structure of the copolymer can vary, depending upon the specific character of the reactants, and mode of preparation. It may form a polyethylenic straight chain to which phenyl and polar alkyls are attached and some incidental alkyls resulting from some branching and chain termination mode. Also, as hereinbefore set forth, a small amount of the peroxide catalyst may enter into the reaction, as well as the final composition containing some unremoved solvent. Regardless of the specific chemical structure, the terpolymer, prepared as described herein, is a very effective pour point depressant. As another advantage to the present invention, the terpolymer is useful in many different oils and thus extends the range of its applicability.
The terpolymer is incorporated in the oil in a sufficient concentration to lower the pour point of the oil to a satisfactory degree. For economical reasons, the additive is used in as low a concentration as is satisfactory for the purpose and may be within the range of from about 0.001% to about 1% but generally is within the range of from about 0.005% to about 0.1% by weight of the oil. It is understood that the pour point depressant may be used in conjunction with other additives normally incorporated in the hydrocarbon oil, which will vary with the particular hydrocarbon oil and may comprise one or more of anti-oxidant, corrosion or rust inhibitor, viscosity index improver, cetane improver, metal deactivator, dye, etc.
The following examples are introduced to illustrate further the novelty and utility of the present invention but not with the intention of unduly limiting the same.
EXAMPLE I
This example describes the preparation of a terpolymer of ethylene, styrene and methylmethacrylate. The preparation was made in a 3 liter rotating autoclave which first was purged with nitrogen and then charged with 5 g. (0.05 mole) methylmethacrylate in 100 g. of benzene, 5.02 g. (0.05 mole) of styrene in 100 g. of benzene and 1 g. (0.007 mole) of tert-butyl peroxide in 100 g. of benzene. The autoclave was sealed tight and purged with ethylene at a pressure of about 70 atmospheres, and then vented. The autoclave next was pressured to 70 atmospheres with ethylene, thus saturating the reaction mixture, heated to 284° F. and maintained at this temperature for 4 hours, after which the autoclave was cooled and 296 g. of liquid product recovered. The liquid product was warmed, filtered, and evaporated (20 torr.) to yield 25 g. of tacky solid. The styrene to methylmethacrylate ratio in the terpolymer is 1:1 and the ratio of ethylene to the total of other reactants is 10.4:1. The average molecular weight of the terpolymer is 2,800.
EXAMPLE II
Another terpolymer preparation was made in substantially the same manner as described in Example I except that the solvent used in this preparation was toluene. Specifically, the rotating autoclave was charged with 5 g. (0.05 mole) of methylmethacrylate in 100 g. of toluene, 5.02 g. (0.05 mole) of styrene in 100 g. of toluene and 1 g. (0.007 mole) of tert-butyl peroxide in 100 g. of toluene. Following purging and pressurizing to 70 atmospheres with ethylene, the autoclave was heated and maintained at 284° F. for 4 hours. After cooling, 308 g. of liquid was withdrawn from the autoclave, filtered and evaporated to remove solvent, to yield 14 g. of soft and tacky dry solid product. The average molecular weight of the terpolymer is 1180.
EXAMPLE III
A terpolymer is prepared in substantially the same manner as described in Example I except that the unsaturated ester is vinyl acetate. The reactants are charged to the rotating autoclave in mole ratios of ethylene:styrene:vinyl acetate of 15:1.5:1. Following completion of the reaction and removal of the benzene solvent, the product is recovered as a solid terpolymer.
EXAMPLE IV
Another terpolymer is prepared in substantially the same manner as described in Example II except that alpha-methylstyrene is used as the phenyl alkylene. The reactants are used in a mole ratio of ethylene:transbeta-methylstyrene:methylmethacrylate of 12:1:1.5. After cooling of the autoclave, filtering and vacuum distillation to remove the solvent, the solid terpolymer product is recovered.
EXAMPLE V
Another preparation is made in the same manner as described in Example II except that vacuum distillation to remove the toluene solvent is omitted and the resultant solution is utilized as a liquid concentrate for adding as a pour point depressant to a hydrocarbon oil.
EXAMPLE VI
The terpolymer prepared as described in Example I was utilized as a pour point depressant in a commercial light cycle oil having a pour point of -2° F. and a boiling range of 358°-709° F. The terpolymer was evaluated at different concentrations, based on active ingredient, ranging from a high of 500 ppm (parts per million) down to a low of 10 ppm. The data was reported in the following table.
TABLE I ______________________________________ Additive Pour Point Concentration Pour Point Depression ppm °F. °F. ______________________________________ None -2 - 500 <-60 >-60 50 -43 >41 25 -25 23 10 -20 18 ______________________________________
From the data in the above table, it will be seen that the terpolymer was very effective in lowering the pour point of the oil. Even in a concentration as low as 10 ppm, the pour point was lowered from -2° to -20° F.
EXAMPLE VII
The terpolymer prepared as described in Example II is used in a concentration of 250 ppm in a commercial No. 2 fuel oil having a boiling range of 428°-677° F. and a pour point of 10° F. The addition of the terpolymer serves to decrease the pour point to -20° F.
EXAMPLE VIII
The flowing properties of crude oil in subarctic areas is improved by incorporating therein 250 ppm of the terpolymer prepared as described in Example I.
EXAMPLE IX
The pour point properties of lubricating oil are improved by incorporating therein 1,000 ppm of the terpolymer prepared as described in Example II.