NO318427B1 - Homogenized flow point lowering composition, homogenization method and use of the composition - Google Patents

Description

The present invention relates to a homogenized pour point lowering composition, a method for homogenization and use of the composition.

Different types of distillate fuel oils such as diesel oils, oils of various lubricating viscosity, automatic transmission oils, hydraulic oil, heating oils require the use of pour point lowering additives to allow them to flow freely at lower temperatures. Often the kerosene is included in such oils as a solvent for wax, especially that present in distillate fuel oils. However, the need for kerosene for use in jet fuel has caused the amount of kerosene present in distillate fuel oils to decrease over the years. This in turn has required the addition of wax crystal modifiers to make up for the lack of kerosene. Furthermore, the requirements for pour point-lowering additives in crude oils may be even more important, as the addition of kerosene is not considered to be economically desirable.

Many of the pour point depressants are inherently waxy, solid materials due to the presence of relatively long hydrocarbyl groups. Such materials can be better handled at room temperature if they are in liquid form, i.e. dissolved or dispersed in a medium.

U.S. patent 4,435,309, House, March 6, 1984, describes a process for liquefying materials which are either waxy solids at ambient temperatures or solid or semi-solid mixtures of such waxy materials and a solvent therefor. A solution of the waxy material in the solvent is formed at elevated temperatures, the solution is cooled to produce a semi-solid to solid phase, and then the mixture is sheared. Among the waxy materials are quaternary ammonium compounds and polyoxyethylated alkylphenols; solvents include mixtures of isopropylamine and water or hexylene glycol.

U.S. patent 3,061,544, Martinek, October 30, 1962, describes a method for producing colloidal dispersions by simultaneously lowering the temperature, pressure and concentration during cutting. This colloid-forming phase is dissolved in a minimum amount of colloid-bearing phase by the application of sufficient heat to produce a solution. The hot, concentrated solution is injected under high pressure through a jet or spray nozzle into a zone of lower pressure and lower temperature where the currents meet, or collide, with the rest of the liquid phase which is also injected under high pressure.

U.S. patent 3,393,078, Lockhart et al., July 16, 1968, discloses an automobile polish prepared by stirring and heating the ingredients until the wax components are dispersed and emulsified as finely molten (or nearly molten) particles, and cooling the resulting emulsion composition to room temperature. The emulsion is stirred rapidly while it is cooled to a temperature below the melting point of the waxes; then the emulsion is stirred slowly while it is allowed to flow from an outlet in the wall of the (mixing) vessel into the container in which it is to be sold.

U.S. patent 1,637-475, Davis et al., 2 August 1927, describes a wax emulsion which uses as an emulsifier a colloidal material which is a mixture of hard and soft soaps. Heating and vigorous stirring of the mass is continued until the wax has been dispersed. When the dispersion has been effected, a cooling medium is circulated through the jacket of the vessel to rapidly cool the mass, while at the same time agitation is continued. When the mass has reached a temperature of around 65°C, it is pressed through a cheese cloth and then cooled slowly to room temperature.

U.S. patent 5,039,437, Martella et al., August 13, 1991, (and U.S. patent 5,082,470, Martella et al., January 21, 1992, a division thereof) discloses alkylphenol-formaldehyde condensate additives for improving the low temperature flow properties of hydrocarbon oils. The polymer composition has a number average molecular weight of at least about 3,000 and a molecular weight distribution of at least about 1.5; in the alkylated phenol reactant, the alkyl groups are predominantly linear, with about 6 to 50 carbon atoms, and average carbon atoms between about 12 and 26, and no more than about 10 mole percent of the alkyl groups on the alkylated phenol have less than 12 carbon atoms and no more than about 10 mol% of the alkyl groups on the alkylated phenol have more than 26 carbon atoms.

U.S. patent 4,564,460, Dorer, Jr., et al., January 14, 1986, (and U.S. Patents 4,559,155, December 17, 1985, 4,565,550, January 21, 1986, 4,575,526, March 11, 1986 and 4,613,342, September 23, 1986, divisions thereof), describe additive combinations for improving cold flow properties of hydrocarbon fuel compositions. The composition comprises a pour point depressant which may be a hydrocarbyl substituted phenol of the formula (R<*>)a—Ar—(OH)b where R<*> is a hydrocarbyl group selected from the group comprising hydrocarbyl groups having from about 8 to about 39 carbon atoms and polymers having at least 30 carbon atoms. Ar is an aromatic group which may include bonded polynuclear aromatic groups represented by the general formula ar—(—Lng—ar—)—w(Q)mw where w is an integer from 1 to about 20. Each Lng is a bridging bond of the type comprising alkylene linkages (e.g. —CH2—among others).

Norwegian patent application 19963723 with priority from 8 September 1995, but published after the filing of the present application's priority applications, describes flow improvers comprising the reaction product of a hydrocarbyl-substituted phenol and an aldehyde. These can be dispersed in, among other things, acetates and aqueous glycol mixtures.

The present invention provides a homogenized liquid pour point depressant composition characterized in that it comprises: (i) a pour point depressant which is a solid at 10°C, which has a number average molecular weight of at least 500 and a chain length of at least 12 carbon atoms, and which comprises the reaction product of ( a) a hydrocarbyl substituted phenol and (b) an aldehyde of 1 to 12 carbon atoms, or a source thereof; and (ii) a liquid medium in which the material from (i) is substantially insoluble at 0°C; wherein the liquid medium is selected from the group consisting of ketones, alcohols, and mixtures of water and a glycol in the weight ratio of 1:2 to 2:1, water : glycol; wherein component (i) is dispersed in component (ii).

The present invention further provides a method for homogenizing a mixture of: (i) a pour point depressant which is a solid at 10°C and which has a number average molecular weight of at least 500 and a chain length of at least 12 carbon atoms, and which comprises the reaction product of (a ) a hydrocarbyl-substituted phenol and (b) an aldehyde of 1 to 12 carbon atoms, or a source thereof; and (ii) a liquid in which the material of (i) is substantially insoluble at 0°C, the liquid being selected from the group consisting of ketones, alcohols and mixtures of water and a glycol in the weight ratio of 1:2 to 2:1, water:glycol;

characterized by the fact that it includes the steps:

(a) heating components (i) and (ii) to a temperature at which (i) is soluble in (ii) or is molten;

(b) mixing the heated components; and

(c) cooling the heated mixture to a temperature at which (i) is substantially insoluble in the liquid (ii).

Furthermore, the invention includes the use of the pour point-lowering composition according to the invention for reducing the pour point of a paraffin-containing liquid.

The present invention is a dispersion of a wax pour point depressant in a material which is a non-solvent for the pour point depressant. The dispersion is homogeneous, at least on a macroscopic scale. The wax pour point depressant is a material having a number average molecular weight of at least 500, preferably at least 700 and more preferably at least 1000, preferably up to 500,000, preferably 50,000, more preferably 5,000. The material is a solid (in the absence of added solvent) at 10°C, preferably also at room temperature, i.e. at least up to about 20°C, and more preferably up to 30 or 40°C or higher. The material has a chain length of at least 12 carbon atoms. The material is also one that acts as a pour point depressant when mixed in a wax-containing hydrocarbon liquid, as measured by ASTM D-97. Suitable materials are the reaction product of (a) a hydrocarbyl substituted phenol with sufficient carbon atoms in the hydrocarbyl substituent such that the product is a solid or semisolid at room temperature, typically a "wax" material, and (b) an aldehyde having 1 to 12, preferably 1 to 4 , carbon atoms or a source therefore.

Hydrocarbyl-substituted phenols are known materials, as are their methods of preparation.

The aromatic group of the hydrocarbyl-substituted compound is thus a simple aromatic benzene nucleus.

Specific examples of the aromatic group are the following:

etc., where Me is methyl and Et is ethyl or ethylene.

This first reactant is a hydroxybenzene compound, i.e. a compound in which at least one hydroxy group is directly bonded to a benzene ring. The number of hydroxy groups per benzene ring will vary from 1 up to the maximum number of such groups that the hydrocarbyl-substituted benzene ring can have while still having at least one, and preferably two, positions, at least some of which are preferably adjacent (ortho) to a hydroxy group, suitable for additional reaction by condensation with aldehydes (described in detail below). Thus, most of the molecules of the reactant will have at least two unsubstituted positions. Most commonly, however, each hydrocarbyl-substituted phenol will contain one benzene nucleus and one hydroxyl group. Naturally, a small group of the aromatic reactant molecules may contain zero hydroxyl substituents. For example, a minor amount of non-hydroxy material may be present as an impurity. However, this will not conflict with the spirit of the invention as long as the starting material is functional and typically contains at least one hydroxyl group per molecule.

The hydroxyaromatic reactant is similarly characterized in that it is hydrocarbyl substituted. The term "hydrocarbyl substituent" or "hydrocarbyl group" is used herein in its normal sense, which is well known to those skilled in the art. Specifically, it refers to a group that has a carbon atom directly attached to the rest of the molecule and is predominantly hydrocarbon in character. Examples of hydrocarbyl groups include: (1) Hydrocarbon substituents, i.e., aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and alicyclic-substituted aromatic substituents, as well as cyclic substituents where the ring is completed via another group of the molecule (eg two substituents together form an alicyclic radical); (2) substituted hydrocarbon substituents, i.e. substituents containing non-hydrocarbon groups which, within the scope of the invention, do not alter the main hydrocarbon substituent (e.g. halo (especially chlorine and fluorine), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso and sulfoxy); (3) heterosubstituents having a predominantly hydrocarbon character, within the scope of the present invention, containing other than carbon in a ring or chain otherwise composed of carbon atoms. Heteroatoms include sulfur, oxygen, nitrogen, and include substituents such as pyridyl, furyl, thienyl and imidazolyl. In general, no more than two, preferably no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically there will be no non-hydrocarbon substituents in the hydrocarbyl group.

Preferably, the hydrocarbyl group is an alkyl group. Preferably, the alkyl group will contain at least 12, more preferably at least 20, and even more preferably at least 30 carbon atoms or, if the alkyl group is a mixture of alkyl groups, the mixture will preferably contain on average at least 30 carbon atoms, typically 31 to 400 carbon atoms, typically 31 to 400 carbon atoms, preferably 31 to 60, and more preferably 32 to 50 or 45 carbon atoms, although this is not necessary. In a preferred embodiment, the alkyl group in the composition will be a mixture of alkyl groups which can vary in quantity from one particular molecule to another. While a fraction of such molecules may contain an alkyl group of fewer than 30 carbon atoms, the composition as a whole will normally be characterized by having alkyl substitution of at least 30 carbon atoms in length. For certain embodiments of the present invention, the alkyl group may be shorter, contain fewer than 30 carbon atoms, e.g. mainly 24 to 28 carbon atoms or 20-24 carbon atoms. The alkyl groups may in all cases be derived from either linear or branched olefin reactants; linear are sometimes preferred, although materials with longer chain lengths tend to increase the proportion of branching. A certain amount of branching appears to be introduced via a rearrangement mechanism during the alkylation process.

In a preferred embodiment, the hydrocarbyl groups used comprise a mixture of alkyl with lengths of mainly 30 µl 36 carbon atoms with a number average number of about 34.4 and a weight average carbon number of about 35.4. This material is characterized by having approximately the following chain length distribution:

The hydrocarbyl substituent thus forms a number average number of more than 30 carbon atoms. Such substituents are preferably alkyl groups where the number-average number of carbon atoms in the alkyl chain is 31-40, more preferably 32-38. The hydrocarbyl group may be derived from the corresponding olefin; for example, a C26 alkyl group is derived from a C26 alkene, preferably a 1-alkene, a C34 alkyl group is derived from a C34 alkene, and mixed length groups are derived from the corresponding mixture of olefins. However, when the hydrocarbyl group is a hydrocarbyl group of at least 30 carbon atoms, it is often an aliphatic group (or a mixture of such groups) prepared from homo- or interpolymers (eg, copolymers, terpolymers) of mono- and diolefins of 2 to 10 carbon atoms , such as ethylene, propylene, butene-1-, isobutene, butadiene, isoprene, 1-hexene, 1-octene, etc. For suitable use as pour point depressants, at least part of the alkyl group or groups, preferably straight chain, i.e. mainly linear. It is believed that this property is preferred to allow the chain to more optimally interact with the chain structure of the wax-forming hydrocarbons. It is observed that in many cases there will be a methyl branch at the point of attachment of the alkyl chain to the aromatic ring, even when an α-olefin is used. It is considered to be within the meaning of straight chain or linear alkyl groups. Likewise, in some cases, part of the alkyl groups may contain lower alkyl branches at the attachment point (or ot position), preferably due to migration of the active site during the alkylation reaction. Typically, the olefins used are 1-mono-olefins such as homopolymers of ethylene. These aliphatic hydrocarbyl groups may also be derived from halogenated (eg, chlorinated or brominated) analogs of such homo- or interpolymers. However, such groups may be derived from other sources, such as monomeric high molecular weight alkenes (e.g. 1-tetraconte) and chlorinated analogues and hydrochlorinated analogues thereof, aliphatic petroleum fractions, especially paraffin waxes and cracked and chlorinated analogues and hydrochlorinated analogues thereof, white oils, synthetic alkenes such as those produced by the Ziegler-Natta process (eg, poly(ethylene) grease) and other sources known to those skilled in the art. Any unsaturation in the hydrocarbyl groups can be reduced or eliminated by hydrogenation according to procedures known in the art. Production by roads or the use of materials that are essentially free of chlorine or other halogens is often preferred for environmental reasons.

In one embodiment, a portion of the hydrocarbyl groups are derived from polybutene. In another embodiment, part of the hydrocarbyl groups are derived from polypropylene. In a preferred embodiment, the hydrocarbyl group is derived from a mixture of substantially unbranched olefins having a chain length of substantially 30-36 carbon atoms as described above.

More than one such hydrocarbyl group may be present, but usually no more than 2 or 3 are present for each benzene ring. Most typically, only 1 hydrocarbyl group is present per benzene ring.

The attachment of the hydrocarbyl group to the aromatic group of the first reactant of the present invention can be accomplished by a number of techniques well known to those skilled in the art. A particularly suitable technique is the Friedel-Crafts reaction, in which an olefin (eg a polymer containing an olefinic bond), or halogenated or hydrohalogenated analogue thereof, is reacted with a phenol in the presence of a Lewis acid catalyst . Procedures and conditions for carrying out such reactions are well known to the person skilled in the art. In, for example, the discussion in the article entitled; "Alkylation of Phenols" in "Kirk-Othmer Encyclopedia of Chemical Technology", Third Edition, Vol. 2, pp. 65-66, Interscience Publishers, a division of John Wiley and Company, N.Y. Other equally suitable and applicable techniques for the preparation of the hydrocarbon-based group of the aromatic group will be apparent to those skilled in the art.

The second component which reacts to form the pour point depressant as described above is an aldehyde of 1 to 12 carbon atoms, or a source thereof. Suitable aldehydes have the general formula RC(0)H, where R is preferably hydrogen or a hydrocarbyl group as described above, although R may comprise other functional groups which do not interfere with the condensation reaction (described below) of the aldehyde with the hydroxyaromatic compound. This aldehyde preferably contains 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms and even more preferably 1 or 2 carbon atoms. Such aldehydes include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, pentanaldehyde, caproaldehyde, benzaldehyde and higher aldehydes. Monoaldehydes are preferred. The most preferred aldehyde is formaldehyde which can be supplied as a solution, but is usually used in the polymeric form as paraformaldehyde. Paraformaldehyde can be considered a reactive equivalent of, or a source for, an aldehyde. Other reactive equivalents may include hydrates or cyclic trimers of aldehydes.

The hydrocarbylphenol and the aldehyde are reacted in relative amounts in the range from about equal molar amounts to about a 30% molar excess of the aldehyde (calculated based on aldehyde monomer). Preferably, the amount of aldehyde is 5 to 20, more preferably 8 to 15, percent greater than the hydrocarbylphenol on a molar basis. The components are reacted under conditions to lead to oligomer or polymer formation. The molecular weight of the product will depend on properties including the equivalent ratio of reactants, the temperature and reaction time, and the presence of impurities. The product may have from 2 to 50 aromatic units repeated in its chain, preferably 3 to 30 such units, more preferably 4 to 14 units. When the hydrocarbylphenol is specifically an alkylphenol with 24-28 carbon atoms in the alkyl chain, and when the aldehyde is formaldehyde, the material will preferably have a number average molecular weight of 1,000 to 24,000, more preferably 2,000 to 18,000, even more preferably 3,000 to 6,000. The molecular weights of materials based on a hydrocarbyl substituent length of about 34 carbon atoms would be proportionally somewhat higher.

The hydrocarbyl phenol and the aldehyde are reacted by mixing the alkyl phenol and the aldehyde in a suitable amount of petroleum thinner or, optionally, another solvent such as an aromatic solvent, e.g. xylene, in the presence of an acid such as sulfuric acid, a sulfonic acid such as an alkylphenylsulfonic acid, para-toluenesulfonic acid, or methanesulfonic acid, an organic acid such as glycosylic acid or Amberlyst™ catalyst, a solid, macroporous, lightly crosslinked sulfonated polystyrene divinylbenzene resin catalyst from Rohm and Haas . The mixture is heated, generally to 90 to 160°C, preferably

100 to 150 or 120°C, for a suitable time, such as 30 minutes to 6 hours, preferably 1 to 4 hours, to remove condensation water. The time and temperature are correlated so that reaction at a lower temperature will generally require a longer time, etc. Determination of the exact conditions is within the knowledge of the person skilled in the art. If desired, the reaction mixture can then be heated to a higher temperature, e.g. 140-180°C, preferably 145-155°C, to further drive away volatile components and drive the reaction to completion. The product may be treated with base such as NaOH if desired, to neutralize the strong acid catalyst and to prepare a sodium salt of the product, if desired, and is then isolated by conventional techniques such as filtration, as appropriate.

The product of this reaction can generally be considered to include polymers or oligomers having the following repeating structure: and positional isomers thereof. However, a part of the formaldehyde is preferably used which is assumed to be incorporated into the molecular structure in the form of substituent groups and cross-linking groups such as those illustrated by the following types, including ether bonds and hydroxymethyl groups:

The pour point depressant according to the present invention is supplied as dispersions in a liquid medium in which it is not normally soluble at 0°C, and preferably also not soluble at room temperature, i.e. around 20°C, or even 30 or 40°C. This means that the medium is initially a liquid at room temperature (around 20°C) and will preferably have a freezing point of 10°C or lower. A preferred medium, especially in mixtures, will have a freezing point as low as 0°C, -20°C, -30°C, -40°C or lower. Furthermore, the medium will not dissolve a significant amount of the pour point depressant at such temperatures, preferably at room temperature. More particularly, the medium will preferably dissolve less than 4% by weight, preferably less than 2 or even 2% by weight, of the pour point depressant at room temperature or moderately elevated temperatures, (in some cases a small soluble fraction may include impurities and unreacted materials, so that the amount of actual pour point depressant dissolved will be proportionally lower, eg lower than 0.5% by weight. Preferably, the medium will remain a non-solvent at 30°C or preferably at 40 to 50°C or higher.

In order for the liquid medium to not be a non-solvent for the pour point depressant, the medium must generally have an appropriate degree of polarity. Polarity can be measured or expressed in many ways. Thus, in one embodiment, the molecules in the solvent will preferably have 10 to 80% by weight of heteroatoms such as oxygen or nitrogen, more preferably 20 to 70%, and more preferably 25 to 60% by weight. Alternatively, the medium can have a dielectric constant of at least 3, preferably at least 10. The above-mentioned parameters will normally be those of the medium as a whole, including all the components that are mixed, if it is in a mixture.

Suitable liquid media include acetates, ketones (eg, acetone, butanone, pentanone, hexanone) or aqueous glycol mixtures (eg, mixtures of ethylene glycol and water) in a weight ratio of 1:2 to 2:1. Among the materials that can be used in combination with water are ethylene glycol and its derivatives, such as monomethyl ether (Methyl Cellosolve™), monoethyl ether (Cellosolve™), monopropyl ether, monobutyl ether and monohexyl ether; diethylene glycol and its derivatives, such as monomethyl ether (Methyl Carbitol™), monoethyl ether (Carbitol™), monopropyl ether, monobutyl ether and monohexyl ether; propylene glycol and its derivatives, including monomethyl ether (Methyl Propasol™), monopropyl ether and monobutyl ether; and dipropyl glycol and its derivatives, such as monomethyl ether (Methyl Dipropasol™"), monopropyl ether and monobutyl ether.

Other suitable materials include alcohols such as butanol, diacetone alcohol (4-hydroxy-4-methyl-2-pentanone), 2,6-dimethyl-4-heptanol (Diisobutyl Carbinol™), hexanol, isopropanol, 2-ethylhexanol and 1-pentanol.

If the liquid material is a mixture of glycol and water, the relative amounts of the materials are such that the water component will not freeze even at low temperatures such as 0 to -40°C. Weight ratios of about 1:1 for such aqueous mixtures are often preferred, more generally ratios of 1:2 to 2:1, preferably 1:1.5 to 1.5:1 are satisfactory.

Many wax pour point depressants are conventionally supplied in concentrate form, containing various amounts of aromatic solvents such as xylenes or a commercially mixed aromatic solvent having a boiling point of about 179°C. The presence of a modest amount of such solvents (e.g., 10% to 50%, e.g., 25%, based on the weight of the pour point depressant/solvent mixture) has sometimes been found to aid in the dispersion of the pour point depressant in the medium, even if its presence is not necessary. If such an aromatic solvent is present, it will be considered a component of the liquid medium and will contribute to the total amount and solvent character (polarity) of the medium.

The dispersed composition also preferably contains a dispersing agent to help form and maintain the dispersion. Dispersants, also known as surfactants, can be classified as anionic, cationic, zwitterionic or nonionic. Anionic surfactants include substances that contain a long lipophilic tail attached to a water-soluble (hydrophilic) group at the other end, where the hydrophilic group contains an anionic group such as a carboxylic acid, sulfonic acid or phenolic group, neutralized by a cation such as an alkali metal or ammonium. The lipophilic tail is preferably an alkyl group, typically having about 8 to about 21 carbon atoms.

Typical anionic surfactants include carboxylic acid salts such as fatty acid salts of the formula RjCOOR2> where R1 is a straight-chain, saturated or unsaturated hydrocarbon radical of 8 to about 21 carbon atoms, and R2 is a base-forming radical such as Li, Na, K or NH4 , which makes the detergent-like surfactant soluble in water or increases the affinity of the surfactant to water. Alternatively, R 2 may be a divalent or polyvalent metal, in which case the appropriate number of acid groups is normally present to give the neutral salt. Multiple valent metal ions include Mg, Ca, Sr, Ba, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Pb and others. Typical fatty acid salts include sodium stearate, sodium palmitate, ammonium oleate and triethanolamine palmitate. Additional carboxylic acid salts useful as anionic surfactants include salts and especially sodium and potassium salts, coconut oil fatty acids and tall oil acids as well as other carboxylic acid salt compounds including amine salts, such as triethanolamine salts, acylated polypeptides and salts of N-laurylsarcosine such as n-dodecanoyl-N-methylglycine- sodium salt.

Other anionic surfactants include aryl and alkylarylsulfonates such as alkylbenzenesulfonate, linear alkylbenzenesulfonates, sodium tetrapropylenebenzenesulfonate, sodium dodecylbenzenesulfonate, benzene, toluene, xylene and cumenesulfonates, ligninsulfonates, petroleum sulfonates, paraffinsulfonates, secondary n-alkanesulfonates, o-olefinsulfonates . potassium dodecyl sulfate and sodium tetradecyl sulfate, acyl sulfonates of the formula R\SO3R2, where R\ and R2 are as defined above, such as sodium lauryl sulfonate, sulfate pea and sulfonated amides and amines, sulfate pea and sulfonated esters such as laurin monoglyceride sodium sulfate, sodium sulfoethyl oleate and sodium lauryl sulfoacetate, sulfuric acid ester salts p such as sulfated linear primary alcohols, sulfated polyoxyethylenated straight chain alcohols and sulfated triglyceride oils, phosphoric and polyphosphoric acid esters, perfluorinated carboxylic acids, and polymeric anionic surfactants such as alginic acids.

Also included are polymeric anionic surfactants such as salts of polymers of alkyl acrylates and/or alkyl methacrylates and acrylic and/or methacrylic acid and salts of partial esters of maleic anhydride-styrene copolymers.

Another group of materials that can be classified as anionic surfactants are those materials known as overbased or superbased materials. These are basic metal salts, preferably alkali or alkaline earth metal salts of acidic organic compounds (carboxylic acids, sulphonic acids, phosphonic acids, phenols, etc.). Overbased materials are generally single-phase, homogeneous Newtonian systems characterized by a metal content in excess of that which would be present for neutralization according to the stoichiometry of the metal and the particular acidic organic compound reacted with the metal. The overbased materials are prepared by reacting an acidic material (typically an inorganic acid or lower carboxylic acid, preferably carbon dioxide) with a mixture comprising an acidic organic compound, a reaction medium comprising at least one inert, organic solvent (mineral oil, naphtha, toluene, xylene, etc. ) for said acidic organic material, a stoichiometric excess of a metal base and a promoter such as a phenol or alcohol. The acidic organic material will normally have a sufficient number of carbon atoms to achieve a degree of solubility in oil and to give a degree of surface activity to the product. The amount of excess metal is usually expressed in terms of metal ratio. The term "metal ratio" is the ratio of the total equivalents of the metal to the equivalents of the acidic organic compound: A neutral metal salt has a metal ratio of 1; a salt with 4.5 times the amount of metal present in a normal salt will have a metal excess of 3.5 equivalents, or a ratio of 4.5.

Overbased materials are usually used as lubricant additives and are well known to those skilled in the art. While they are useful for some applications, the scope of their application may be different from that of other surfactants. I.e. they have been observed from time to time to deposit what is believed to be calcium carbonate after exposure to an electric field. Nevertheless, in situations where there is no problem, their use may be appropriate, and they are accordingly considered to be within the scope of the present invention. Patents describing techniques for preparing basic salts and sulfonic acids, carboxylic acids, and mixtures of two or more of these include U.S. Pat. patents 2,501,731; 2,616,905; 2,616,911; 2,616,925; 2,777,874; 3,256,186; 3,384,585; 3,365,396; 3,320,162; 3,318,809; 3,488,284 and 3,629,109.

Cationic surfactants are similar to anionic surfactants, except that the surfactant part of the molecule has a positive charge. Examples of cationic surfactants include long-chain amines and their salts, such as primary amines derived from animal and vegetable fatty acids and tall oils and synthetic C 2 -C 1 g primary, secondary or tertiary amines; diamines and their salts, quaternary ammonium salts including tetra-alkylammonium salts and imidazolinium salts derived from e.g. tallow or hydrogenated tallow or N-benzyl-N-alkyldimethylammonium halides; polyoxyethylenated long chain amines: quaternized polyoxyethylenated long chain amines; and amine oxides such as N-alkyldimethylamine oxides (which are actually zwitterionic) such as cetyldimethylamine oxide or stearyldimethylamine oxide.

Zwitterionic surfactants include amino acids such as 1-N-alkylamino-propionic acids, N-alkyl-6-iminodipropionic acids, imidazoline carboxylates, N-alkyl betaines, sulfobetaines and sultaines.

Non-ionic surfactants which are preferred for the present invention are corresponding materials in which the polar functionality is not provided by an anionic or cationic group, but by a neutral polar group such as typically an alcohol, amine, ether, ester -, ketone or amide function. Typical nonionic surfactants include polyoxyethylenated alkylphenols such as polyoxyethylenated p-nonylphenol, p-octylphenol or p-dodecylphenol, polyoxyethylenated straight chain alcohols derived from coconut oil, tallow or synthetic materials including oleyl derivatives; polyoxyethylenated polyoxypropylene glycols (block copolymers of ethylene oxide and propylene oxide), typically with molecular weights of from 1,000 to 30,000; polyethylene glycol; polyoxyethylenated mercaptans; long chain carboxylic acid esters including glyceryl and polyglyceryl esters of natural fatty acids, propylene glycol esters, sorbitol esters, polyoxyethylene sorbitol esters, polyoxyethylene glycol esters and polyoxyethylene fatty acids; alkanolamine "condensates", e.g. the condensates prepared by reaction of methyl or triglyceride esters of fatty acids with equimolar or twice the amount of alkanolamine; tertiary acetylenic glycols; polyoxyethylenated silicones prepared by reaction of a reactive silicone intermediate with a capped allyl polyalkylene oxide such as propylene oxide or mixed ethylene oxide/propylene oxide copolymer; N-alkyl pyrrolidones and alkyl poly-glycosides (long-chain acetals of polysaccharides). Many of these and other ionic and nonionic surfactants are discussed in Rosen, "Surfactans and Interfacial Phenomena", John Wiley & Sons, pp. 7-31, 1989.

Certain materials normally characterized as nonionic surfactants may bear some resemblance to certain of the liquid media described above. If a distinction between these components is necessary, a material can be classified as a non-ionic surfactant for the purposes of the present invention if it shows the characteristics of a non-ionic surfactant and is furthermore a solid at room temperature, preferably at 30°C or 40°C. Materials that are liquids at these temperatures, especially at room temperature and below, can be classified rather as a component of the liquid medium.

Additional nonionic surfactants include more specifically ethoxylated coco amide, oleic acid, t-dodecyl mercaptan, modified polyester dispersants, ester, amide or mixed ester amide dispersants based on polyisobutenyl succinic anhydride, dispersants based on polyisobutylphenol, ABA-type block copolymer-non -ionic dispersants, acrylic graft copolymers, octylphenoxypolyethoxyethanol, nonylphenoxypolyethoxyethanol, alkyl aryl ethers, alkylaryl polyethers, amine polyglycol condensates, modified polyethoxy adducts, modified terminated alkyl aryl ethers, modified polyethoxylated straight chain alcohols, terminated ethoxylates of linear, primary alcohols, high molecular weight tertiary amines such as l- hydroxyethyl-2-alkylimidazolines, oxazolines, perfluoroalkyl sulphonates, sorbitan fatty acid esters, polyethylene glycol esters, aliphatic and aromatic phosphate esters. Also included are the reaction products of hydrocarbyl-substituted succinic acid acylating agents and amines. These reaction products and methods for their preparation are described in U.S. Pat. the patents 4,234,435; 4,952,328; 4,938,881 and 4,957,649.

Other nonionic surfactants include functionalized polysiloxanes. These materials include functional groups such as amino, amido, imino, sulfonyl, sulfoxyl, cyano, hydroxy, hydrocarbyloxy, mercapto, carbonyl (including aldehydes and ketones), carboxy, epoxy, acetoxy, phosphate, phosphonyl and haloalkyl groups. These polysiloxanes can be linear or branched and generally have a molecular weight above 800, e.g. up to 10.00 or 20.000. The functionality can be randomly distributed on the poly tag chain or present in blocks. The functionality may be present as alkyl or alkaryl groups as well as groups such as -(C2H40)a-(C3HgO)D-R where a and b are independent numbers from 0 to about 100, provided that at least one of a and b is at least 1, and R is H, acetoxy or a hydrocarbyl group. Other suitable substituent groups may include C 3 H 6 X, where X is OH, SH or NH 2 . Examples of such materials include Silwet™ surfactants from Union Carbide and Tegopren™ silicone surfactants from Goldschmidt Chemical Corp., Hopewell, Va.

Nonionic surfactants include polyoxyalkenalkyl alcohols or phenols, such as ethoxylated nonylphenol, alkanoates (preferably partial alkanoates) of polyalcohols such as glyceryl mono-oleate, glyceryl monolaurate, sorbitan mono-oleate, sorbitan sesquioleate, sorbitan monolaurate and sorbitan sesquilaurate and 4,4- bishydroxylmethyl-2-heptadecenyl-2-oxazoline. Preferred materials include tall oil fatty acid neutralized with diethanolamine, Triton™ surfactants (from Rohm & Haas), including the octylphenol series with 1 to 70 ethylene oxide units and the nonylphenol series with 4 to 40 ethylene oxide units, Neodol™ surfactant ethoxylates (from Shell Chemical Co.) with 2 to 13 ethylene oxide units, Igepal™ surfactants (from Rhone-Poylenc) containing 7 to 50 ethylene oxide units and Tergititol™ surfactants (from Union Carbide) containing 4 to 41 ethylene oxide units. The commercial materials mentioned above are generally linear, primary alcohol ethoxylates or (for Triton materials) branched alkyl phenol ethoxylates.

The relative amounts of the fat pour point depressant, the liquid medium and the possible surfactant can vary widely, but are preferably in the range of (20-60): (40-80):(0-10), preferably (30-50=:( 50-70):(1-7), more preferably (35-45):(55-65):(2-6), especially about 38:58:4 parts by weight.

The dispersed composition according to the present invention is prepared by first heating the components to a temperature at which the wax material can be dispersed by suitable means in the liquid medium plus the eventual surfactant, if present. This condition may be encountered if, at a suitably elevated temperature, the waxy material is soluble in the liquid medium. Normally, such solubility will be determined not only by the inherent solubility characteristics of the wax material and the solubility properties of the medium, but also the boiling point of the liquid medium. Preferably, the combination of the liquid medium and the wax material is such that, in this embodiment, a suitable amount of solubility, e.g. 80 g per 100 g of medium, obtained at or below the normal boiling point of the medium, although increased solubility can normally be obtained, if desired, by combining the components under elevated pressure to raise the boiling point of the medium. Alternatively, improved dispersibility of the wax material can be achieved by heating the mixture to a temperature above the melting point of the wax material, even if the wax material does not dissolve in the medium. More generally, the mixture is heated until the composition becomes liquid. Finally, it is possible in certain cases to achieve suitable dispersibility for materials which neither dissolve nor melt at elevated temperatures, provided that suitable mechanical means are used for dispersion. The heated components, especially if they are in a liquid state (molten or dissolved), are then mixed to ensure dispersion. This mixing can be carried out under conditions of high shear or cavitation. "High shear" will normally mean shear conditions at at least 10^ sec.-<l>, preferably at least 10^ sec.-<l> and more preferably at least 10^ sec.-<l>. Cavitation conditions are also considered to be high shear conditions; cavitation generally involves the formation of microscopic bubbles in a liquid that expand under the influence of ultrasonic energy and then implode with an intense shearing action. Devices capable of producing sufficiently high shear or cavitation conditions include a Sonicator™, a high-intensity ultrasonic processor in which high-frequency electrical voltage (eg, 20 kHz) is converted into mechanical vibration energy that is directed into a liquid sample at

using a probe. Also included are high shear dispersers (such as the Dispersator™),

in which a high speed rotor is held a short distance from a fixed stator to create an extremely high shear environment due to the mechanical and hydraulic forces as the fluid passes into the rotor and is expelled at high speed through the stator

or a Microfluidizer™ (Microfluidics Intl. Inc.) in which two high-pressure streams interact at high velocities in defined microchannels, whereby shear, impact and cavitation forces typically produce submicron particles. The temperature to which the composition will be heated will depend on the melting, solubility and volatility characteristics of the materials used; typical heating may be from 40 to 100°C, preferably 50 to 90°C, more preferably 70 to 83°C. The heated mixture is then cooled to a temperature at which the wax material is substantially insoluble and will normally exist in a solid or semi-solid state while maintaining the mixing conditions. The resulting mixture is a stable dispersion.

In one embodiment, the pour point depressant is melted, and an appropriate amount of surfactant is added to the melt while stirring. An appropriate amount of correspondingly heated liquid medium (such as water/glycol) is added and the components mixed. The mixture is then subjected to high shear mixing or sonicated either while it is still hot, or during the cooling process or alternatively after the mixture has cooled.

Materials produced by any of the preceding methods may also be described as homogenized materials. That is they are materials in which, due to the above-described treatment, the particle size of the suspended material is relatively reduced and preferably relatively uniform, and the suspended particles are relatively evenly distributed throughout the medium, and remain dispersed for a commercially reasonable period of time.

The dispersions according to the present invention can be used to add pour point depressants in a concentrated form to wax (paraffin) containing hydrocarbon materials such as a crude oil or a fraction of crude oil, such as residual oil, vacuum gas oil or vacuum residual oils (Bunker C crude oils), i.e. oils from natural sources and partially refined, including partially processed petroleum derived oils. The amount of pour point depressant employed in the paraffin containing liquid will be an amount suitable to lower the pour point thereof by a measurable amount, ie at least 0.6°C (1°F), preferably at least 2°C (3 or 4°F ), more preferably 3°C (5°F) and even more preferably 6°C (10°F). This reduction in pour point can easily be determined by the person skilled in the art using the methodology according to ASTM D-97. Typically, the amount of pour point depressant used, apart from the liquid medium in which it is dispersed, will be 50 to 10,000 parts per million by weight (ppm), preferably 100 to 5000 ppm, more preferably 200 to 2000, based on the fluid to which it is added. The total amount of concentrate to feed will be proportionally higher, depending on the concentration of the pour point depressant in the concentrate.

EXAMPLES

Example 1

Ethylene glycol, 571.5 g, and distilled water, 571.5 g, are mixed with stirring and heated to about 50°C (120°F). Separately, 1143.0 g of the condensation product of formaldehyde and alkylphenol, the alkyl substituents having a length of mainly C^q^ carbons, as described above (50% active ingredient in 50% diluted mineral oil) and 114.3 g of a dispersant composition of 75.6 wt% tall oil fatty acid and 24.4 wt% diethanolamine are mixed, heated until melting occurs (about 82°C, 180°F), and then mixed with sufficient shear over a period of about 10 minutes to produce a uniform mixture . The heated ethylene glycol/water mixture is added to the second mixture using sufficient shear over a period of 20 minutes.

The resulting mixture is cooled, then passed twice through a Micronizer™ set up with a "3669" interaction chamber (to produce 75 micron particles) and a 3839 back pressure module (200 micron), with the pressure set at 170 mPa (25,000 psi) . The fully processed material is collected.

Example 2

Into a Pyrex™ beaker is placed (a) 15 parts by weight of a pour point depressant comprising the condensation product of formaldehyde and alkylphenol, wherein the alkyl substituents are predominantly C30-36 carbons in length, as described above (50% active ingredient in 50% diluent mineral oil) and (b) 1.5 parts by weight of a dispersion composition of 75.6 weight percent tall oil fatty acid and 24.4 weight percent diethanolamine. The mixture is heated to 82°C (180°F) with stirring on a hot plate and to the mixture is slowly added a mixture of (c) 7.5 parts by weight of ethylene glycol and 7.5 parts by weight of water, which had been preheated to 50-70 °C (120-160°F). When addition is complete, the mixture is passed through a Microfluidizer™ and cooled to room temperature.

Example 3

Example 2 was repeated instead with the alkylphenol condensation product, component (a) being 15 parts by weight of the pour point depressant from Example 1.

Except in the examples, or where otherwise explicitly stated, all numerical amounts in this description are specific amounts of materials, reaction conditions, molecular weights, carbon atom numbers, etc., to be understood as modified by the word "about". Unless otherwise indicated, each chemical or composition referred to herein shall be understood to be a commercial material which may contain the isomers, by-products, derivatives and other such materials normally understood to be present in commercial grade. However, the amount of each chemical component present is exclusive of any solvent or diluent oil that may typically be present in the commercial material unless otherwise indicated. As used herein, the term "consisting principally of" permits the inclusion of substances which do not materially affect the inherent and novel characteristics of the composition of the present invention.

Claims (12)

1. Homogenized pour point depressant composition, characterized in that it comprises: (i) a pour point depressant which is a solid at 10°C, which has a number average molecular weight of at least 500 and a chain length of at least 12 carbon atoms, and which comprises the reaction product of (a) a hydrocarbyl substituted phenol and (b) an aldehyde of 1 to 12 carbon atoms, or a source thereof; and (ii) a liquid medium in which the material from (i) is substantially insoluble at 0°C; wherein the liquid medium is selected from the group consisting of ketones, alcohols, and mixtures of water and a glycol in the weight ratio of 1:2 to 2:1, water : glycol; wherein component (i) is dispersed in component (ii). 2. Composition according to claim 1, characterized in that the aldehyde is formaldehyde or a source thereof. 3. Composition according to claim 1, characterized in that the liquid medium has a freezing point of 10°C or lower. 4. Composition according to claim 1, characterized in that the liquid medium comprises about 10 to 80% by weight of heteroatoms. 5. Composition according to claim 1, characterized in that the liquid medium has a dielectric constant of at least about 3. 6. Composition according to claim 1, characterized in that the relative weight ratio of the components (i):(ii) is (20 to 60):(40 to 80). 7. Composition according to claim 1, characterized in that it further comprises (iii) a dispersing agent in an amount suitable to assist in the formation and maintenance of the dispersion of component (i) in component (ii). 8. Process for homogenizing a mixture of: (i) a pour point depressant which is a solid at 10°C and which has a number average molecular weight of at least 500 and a chain length of at least 12 carbon atoms, and which comprises the reaction product of (a) a hydrocarbyl-substituted phenol and (b) an aldehyde of 1 to 12 carbon atoms, or a source thereof; and (ii) a liquid in which the material of (i) is substantially insoluble at 0°C, the liquid being selected from the group consisting of ketones, alcohols and mixtures of water and a glycol in the weight ratio of 1:2 to 2:1, water:glycol; characterized in that it comprises the steps of: (a) heating the components (i) and (ii) to a temperature at which (i) is soluble in (ii) or is molten; (b) mixing the heated components; and (c) cooling the heated mixture to a temperature at which (i) is substantially insoluble in the liquid (ii). 9. Method according to claim 8, characterized in that components (i) and (ii) are heated to a temperature of 40 to 100°C. 10. Method according to claim 8, characterized in that the heated components are mixed under conditions of high shear or cavitation. 11. Method according to claim 8, characterized in that the cooling in step (c) is carried out under mixing conditions. 12. Use of a pour point-reducing amount of the composition according to claim 1 for reducing the pour point of a paraffin-containing liquid.