AQUEOUS DISPERSIONS OF PARAFFIN INHIBITORS

Abstract

Aqueous dispersion of paraffine inhibitors, comprising a continuous aqueous phase comprising water and a water-miscible organic solvent, a dispersed phase comprising at least one paraffin inhibitor component, and at least one anionic surfactant, methods of manufacturing such aqueous dispersions, and the use of such aqueous dispersions as paraffin inhibitor or pour point depressant for crude oil or other hydrocarbon fluids, such as fuel oils or diesel.

Claims

1.-46. (canceled)

47. An aqueous dispersion comprising at least (A) a continuous aqueous phase comprising water and a water-miscible organic solvent, (B) a dispersed phase comprising at least one paraffin inhibitor component having a melting point of not more than 100 C., wherein the amount of the paraffin inhibitor component is from 10% to 60% by weight relating to the total of all components of the aqueous dispersion, and the paraffin inhibitor component comprises at least 30% to 100% by weightrelating to the total of the paraffin inhibitor componentof at least one polymeric, oil-soluble paraffin inhibitor (X), 0% to 70% by weightrelating to the total of the paraffin inhibitor componentof a hydrocarbon or a hydrocarbon mixture having a boiling point of at least 100 C., and (C) at least one surfactant (S), wherein the surfactant (S) is anionic and comprises at least one anionic group selected from sulfonate, sulfate, phosphonate or phosphate groups, the amount of the surfactants (S) is from 1% to 7% by weight relating to the paraffin inhibitor component, and the D.sub.50 particle size (volume size distribution) of the dispersed phase, measured by dynamic light scattering is from 50 nm to 500 nm.

48. The aqueous dispersion according to claim 47, wherein the melting point of the paraffin inhibitor component is from 30 C. to 95 C.

49. The aqueous dispersion according to claim 47, wherein the paraffin inhibitor component comprises 60% to 90% by weight of the polymeric, oil-soluble paraffin inhibitor(s) (X), and 10% to 40% by weight of the hydrocarbon or a hydrocarbon mixture.

50. The aqueous dispersion according to claim 47, wherein the water-miscible organic solvent is at least one selected from the group of ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, ethylene glycol monomethyl ether and propylene glycol monomethyl ether, dipropylene glycol monomethyl ether and glycol monobutyl ether.

51. The aqueous dispersion according to claim 47, wherein the amount of water in the aqueous phase (A) is from 20% to 40% by weight, and the amount of water-soluble organic solvents is from 60% to 80% by weight, in each case based on the amount of all components of the aqueous phase, and wherein the amount of the paraffin inhibitor component is from 20% to 35% by weight, relating to the total of all components of the aqueous dispersion.

52. The aqueous dispersion according to claim 47, wherein the anionic surfactants comprise at least an alkyl ether sulfate having the general formula (I)
R.sup.7O(CH.sub.2CHR.sup.8O).sub.nSO.sub.3.sup.M.sup.+(I) wherein R.sup.7 is linear, branched or cyclic alkyl group having 6 to 36 carbon atoms, R.sup.8 is a group selected from H, methyl or ethyl, with the provisio, that at least 50 mol % of the groups R.sup.7 are H, M is HE or a monovalent counterion, and n is a number from 0 to 60.

53. The aqueous dispersion according to claim 52, wherein R.sup.7 has 8 to 20 carbon atoms, and n is a number from 2 to 20.

54. The aqueous dispersion according to claim 47, wherein the polymeric, oil-soluble paraffin inhibitor (X) is a paraffin inhibitor (X1) comprising, as monomers, -olefins having 10 to 60 carbon atoms, and monoethylenically unsaturated monomers comprising carboxylate groups, where some or all of the carboxylate groups have been reacted with aliphatic, cycloaliphatic or aromatic alcohols and/or primary amines, with the proviso that at least 50 mol % of the alcohols or primary amines are linear aliphatic alcohols or linear aliphatic amines having 16 to 32 carbon atoms.

55. The aqueous dispersion according to claim 54, wherein the polymeric, oil-soluble paraffin inhibitor (X1) comprises, as monomers, 40% to 60 mol % of -olefins having 10 to 32 carbon atoms, and 60% to 40 mol % of maleic acid, where at least a part of the carboxylate groups have been reacted with aliphatic, cycloaliphatic and/or aromatic alcohols and/or primary amines, with the proviso that at least 50 mol % of the alcohols are or primary amines are linear aliphatic alcohols or linear primary amines having 16 to 32 carbon atoms, and where the degree of esterification or amidation is 30% to 60%, based on the number of all carboxylate groups present.

56. The aqueous dispersion according to claim 47, wherein the polymeric, oil-soluble paraffin inhibitor (X) is a paraffin inhibitor (X2) comprising monoethylenically unsaturated monomers comprising at least alkyl(meth)acrylates of the general formula H.sub.2CC(R.sup.1)COOR.sup.2 (I), wherein R.sup.1 is H or a methyl group and R.sup.2 is a linear alkyl group having 12 to 60 carbon atoms.

57. The aqueous dispersion according to claim 56, wherein additionally alkyl(meth)acrylates according to the following formula are present
H.sub.2CC(R.sup.1)COOR.sup.3(II), wherein R.sup.1 is H or a methyl group and R.sup.3 is an alkyl group selected from cyclic or branched alkyl groups having 1 to 36 carbon atoms or linear alkyl groups having 1 to 11 carbon atoms.

58. The aqueous dispersion according to claim 47, wherein the polymeric, oil-soluble paraffin inhibitor (X) is a paraffin inhibitor (X3) available by radical polymerization alkyl(meth)acrylates of the general formula H.sub.2CC(R.sup.1)COOR.sup.2 (I), wherein R.sup.1 is H or a methyl group and R.sup.2 is a linear alkyl group having 12 to 60 carbon atoms, in the presence of ethylene-vinylester copolymers.

59. The aqueous dispersion according to claim 47, wherein the polymeric, oil-soluble paraffin inhibitor (X) is a paraffin inhibitor (X4) which is a copolymer comprising at least ethylene and a vinyl ester of the general formula H.sub.2CCHO(O)CR.sup.4 (I) where R.sup.4 is H or a C.sub.1- to C.sub.4 alkyl moiety.

60. The aqueous dispersion according to claim 47, wherein the polymeric, oil-soluble paraffin inhibitor (X) is a paraffin inhibitor (X5) which is a copolymer comprising at least ethylene, a vinyl ester of the general formula H.sub.2CCHO(O)CR.sup.4 (I) where R.sup.4 is H or a C.sub.1- to C.sub.4 alkyl moiety and a (meth)acrylate of the general formula H.sub.2CC(R.sup.5)COOR.sup.6 wherein R.sup.5 is H or methyl, and R.sup.6 is an alkyl moiety having from 4 to 18 carbon atoms.

61. The aqueous dispersion according to claim 47, wherein the polymeric, oil-soluble paraffin inhibitor (X) is a paraffin inhibitor (X6), which is a hyperbranched or dendritic polymer which comprises terminal hydrophobic groups.

62. The aqueous dispersion according to claim 61, wherein the paraffin inhibitor (X6) is a hyperbranched polyester obtainable by (a) reacting a hydroxyl group containing carboxylic acid with at least one carboxylic acid group and at least two hydroxyl groups with a diol having a molecular weight of more than 100 g/mol, optionally in the presence of at least one further reactant, wherein the at least one further reactant is a polyol having at least three hydroxyl groups under a reaction condition allowing ester and ether formation; and (b) reacting the mixture resulting from step (a) with a hydrophobic carboxylic acid resulting in the hyperbranched polyester mixture.

63. A process for producing an aqueous dispersion according to claim 47, which comprises (a1) Providing an oil-in-water emulsion by mixing the paraffin inhibitor component at a temperature above its melting point with at least water and the surfactant(s) (S) and distributing it in the aqueous phase, (a2) homogenizing the oil-in-water emulsion by means selected from the group of a homogenizer, ultrasound treatment, or a rotor-stator disperser, and (a3) adding a water-miscible organic solvent, wherein the addition may be carried out at any stage of the process.

64. A process for producing an aqueous dispersion according to claim 47, which comprises (b1) providing an oil-in-water emulsion by mixing oil-soluble, monoethylenically unsaturated monomers for forming a polymeric, oil-soluble paraffin inhibitor (X) with the surfactant(s) (S) and at least a portion of the aqueous phase, and (b2) homogenizing the oil-in-water emulsion by means of a homogenizer, ultrasound treatment, or a rotor-stator disperser, and (b3) adding initiators for radical polymerization to the homogenized oil-in-water emulsion and polymerizing, thereby obtaining a paraffin inhibitor component which is a dispersed phase in a continuous aqueous phase.

65. A fuel or fuel oil comprising at least one aqueous dispersion according to claim 47, wherein the aqueous dispersion is used in such an amount that the concentration of the paraffin inhibitors (X) is from 10 ppm to 3,000 ppm by weight based on the fuel oil.

66. A fuel according to claim 65, wherein the fuel is a diesel fuel (absent any additives) with a Cloud Point value according to ASTM D2500/ASTM D97 of 0 to 15 C. and/or with a content of paraffines of from 10 to 30% by weight.

Description

[0230] The following examples are deemed to further illustrate the invention:

Test Methods

Particle Size Distribution

[0231] Particle size distributions were measured for the emulsion after homogenization or ultrasound treatment and for the final product.

[0232] The particle sizes/particle diameters or particle radii indicated here for the polymer particles are particle diameters and were determined by means of photon correlation spectroscopy (PCS), also known as quasi-elastic light scattering (QELS) or dynamic light scattering. In the present invention, particle size was determined by using a NANO-Flex particle sizer from Microtrac (Microtrac Retsch GmbH, Haan, Germany) using a 780 nm laser light (3 mW) at a 180 scattering angle. Measurements were done with samples tel quel diluted to the required concentration, determined by the equipment, with demineralized water at room temperature. A measurable concentration for the equipment is typically reached when ca. 3 drops of the sample were dispersed in 10 ml of demineralized water. The values reported are D50 values in nm (50% of the particlesthe D50 value) of the particle population based on their volume size distribution.

Dynamic Viscosity

[0233] The dynamic viscosity of the dispersion was determined using a Brookfield viscosimeter (model DV-E). A sample of 150 ml was brought to the desired temperature (20 or 23 C.) using a thermostat bath. The LV-type spindle belonging to the range to be measured was connected to the Brookfield viscosimeter, and immersed slowly into the sample until the mark on the spindle was on the same level as the surface of the liquid to be measured. The measurement speed was set in the range of 50 to 100 rpm. The measurement was started and the value shown on the display was recorded.

Molecular Weight Determination

[0234] GPC was measured on an Agilent 1260 Infinity apparatus against polystyrene standards in 5 mg/ml THF solutions on 2 sequential PolyPore 300 mm7.5 mm Agilent columns at 40 C. and 1 ml/min flow. Detection of the signals was done by refractive index and the data were processed using Agilent GPC/SEC Software Version 1.2.

Synthesis of Aqueous Dispersions

Starting Materials

[0235]

TABLE-US-00002 Component Chemical description Behenylacrylate Mixture of linear C18, C20, C22 alkylacrylates (C16 0-5% C18 40-55%, C20 0-15%, C22 35-45% by weight) Stearylacrylate Mixture of linear C16, C18 alkylacrylates (C14 0-3%, C16 47-52%, C18 42-48% by weight) EVA-1 copolymer of 67% by weight of ethylene and 33% by weight of ethylene acetate, Melt Index (190 C., 2, 16 kg) 21 g/10 min EVA-2 copolymer of 70% by weight of ethylene and 30% by weight of ethylene acetate, melt viscosity @ 120 C. = 70 mPas Solvesso 150 ND Mixture of high boiling aromatic hydrocarbons, distillation range 183 C. to 194 C., flash point 64 C. Shellsol D70 Mixture of high-boiling aliphatic hydrocarbons (predominantly C.sub.11-14 paraffins), initial boiling point 203 C., dry point 237 C., flash point 78 C. Brggolite FF6M Commercially reducing agent (sulfinic acid derivative) Anionic surfactant 1 Aqueous solution comprising 31 wt.-% of n-C.sub.12/14O(CH.sub.2CH.sub.2O).sub.4SO.sub.3Na n-C.sub.12/14 are linear alkyl groups having 12 and 14 carbon atoms Non-ionic surfactant 1 n-C.sub.16/18O(CH.sub.2CH.sub.2O).sub.11H n-C.sub.16/18 are linear alkyl groups having 18 and 18 carbon atoms Non-ionic surfactant 2 i-C.sub.13O(CH.sub.2CH.sub.2O).sub.7H i-C.sub.13 is the branched alkyl group of a C.sub.13 oxo alcohol Non-ionic surfactant 3 n-C.sub.16/18O(CH.sub.2CH.sub.2O).sub.50H t-dodecylmercaptane chain transfer agent t-butylhydroperoxide radical initiator 1,2 propanediol water-miscible organic solvent Monoethylene glycol water-miscible organic solvent KOH neutralization agent

Method A

Dispersion of a Dre-Prepared Pour Point Depressant in an Aqueous Phase

EXAMPLE 1

Aqueous Dispersion of an Esterified Copolymer of Maleic Acid Anhydride and C.sub.20/24 Olefines (Paraffin Inhibitor Type (X1)) in Solvesso 150 ND (Polymer Solvent 75/25 wt/wt) Stabilized by 4 Wt.-% of Anionic Surfactant (25 wt.-% of Polymer in Dispersion)

(The Percentages Relate to the Total of all Components)

Synthesis of the Paraffin Inhibitor Component

[0236] In a 1.sup.st step, 271 g of maleic acid anhydride and 829 g of a commercially available mixture of C.sub.20 to C.sub.24 -olefines are radically polymerized at a temperature of about 140 C. by adding 11.2 g of di-tert-butyl peroxide within a period of 5 h, thereby obtaining a copolymer of maleic acid anhydride and C.sub.20/24 -olefines.

[0237] In a 2.sup.nd step, 775.5 g Solvesso 150 ND and 1347.3 g of Behenyacrylate is added at a temperature of 145 C. to the prepolymer obtained in the 1.sup.st step and the mixture stirred for about 8 h. The alcohols react with the maleic acid anhydride groups under ring opening thereby yielding maleic acid ester groups.

[0238] The product comprises 75 wt.-% of a maleic acid ester-olefine copolymer (M.sub.w18,000 g/mole) and the remainder is Solvesso ND 150. The melting point of the mixture is about 40 C.

Preparation of an Aqueous Dispersion

[0239] For the preparation of a stable oil/water emulsion 249.6 g of the melted paraffin inhibitor component was placed into a pre-heated reactor at 65 C. While stirring, 32.2 g of an aqueous solution of the anionic surfactant 1 (31 wt.-%) were added slowly, followed by 129 g of water and 92 g of 1,2-propanediol. After stirring for 15 min, a preheated (60 C.) solution of 3.2 g of solid KOH in 130 g of water and 104 g of 1,2-propanediol was added slowly and stirred for another 15 min.

[0240] Subsequently, the warm pre-emulsion was poured into the addition funnel of a Gaulin type homogenizer (APV 1000 SPX Flow) and while stirring in the funnel, directly treated once at 500 bar valve setting and at 60 C., resulting into a stable emulsion with a D50 droplet size of 246 nm which was collected from the homogenizer via the exit tube into a transport flask.

[0241] The warm emulsion was directly placed back in a reactor and cooled to RT under stirring over one hour.

[0242] Afterwards it was filtered via a 125 m filter into a container. No coagulum was found. The final dispersion was obtained as a white opaque, slightly viscous liquid.

[0243] The resulting particle size of the dispersion D.sub.50 was monomodal at 269 nm and the pH was 6.9. The dynamic viscosity of the aqueous dispersion was 40 mPas (at 23 C.).

[0244] The obtained dispersion comprises (the numbers relate to the total of all components of the aqueous dispersion):

TABLE-US-00003 Paraffin inhibitor component 33.7 wt.-% (polymer + org. solvent) polymer (75 wt.-% of paraffin 25.3 wt.-% inhibitor component) Anionic surfactant 1.3 wt.-% Water 38.0 wt.-% Propanediol 26.5 wt.-% KOH 0.4 wt.-%

[0245] The amount of anionic surfactant relating to the paraffin inhibitor component (comprising polymer and organic solvent (see above)) was 4 wt.-%. The proportion of water/propanediol (wt./wt.) was 59:41.

EXAMPLE 2

Aqueous Dispersion of an Esterified Copolymer of Maleic Acid Anhydride and C.sub.20/24 Olefines (Paraffin Inhibitor Type (X1) in Solvesso 150 ND (Polymer/Solvent 75/25 wt/wt) Stabilized by 4 Wt.-% of Anionic Surfactant (35 wt.-% of Polymer in Dispersion)

(The Percentages Relate to the Total of all Components)

Synthesis of the Paraffin Inhibitor Component

[0246] The synthesis was carried out as in example 1.

Preparation of an Aqueous Dispersion

[0247] For the preparation of a stable oil/water emulsion 328 g of melted paraffin inhibitor component 1 was placed into a pre-heated reactor at 65 C. While stirring, 42.3 g of an aqueous solution of the anionic surfactant 1 (31 wt.-%) was added slowly, followed by 134 g of water and 110 g of 1,2-propanediol. After stirring for 15 min, a preheated (60 C.) solution of 4.19 g of solid KOH in 41.9 g of water and 41.9 g of 1,2-propanediol was added slowly and stirred for another 15 min.

[0248] Subsequently, the warm pre-emulsion was poured into the addition funnel of a Gaulin type homogenizer (APV 1000 SPX Flow) and while stirring in the funnel, directly treated once at 500 bar valve setting and at 60 C., resulting into a stable emulsion with a D50 droplet size of 280 nm, which was collected from the homogenizer via the exit tube into a transport flask.

[0249] Afterwards it was filtered via a 125 m filter into a container. No coagulum was found. The final dispersion was obtained as a white opaque, slightly viscous liquid.

[0250] The warm emulsion was directly placed back in a reactor and cooled to RT under stirring over one hour.

[0251] The resulting particle size of the dispersion D.sub.50 was monomodal at 278 nm, and the pH was 7.0. The dynamic viscosity of the aqueous dispersion was 100 mPas (at 23 C.).

[0252] The obtained dispersion comprises (the numbers relate to the total of all components of the aqueous dispersion):

TABLE-US-00004 Paraffin inhibitor component 46.7 wt.-% (polymer + org. solvent) polymer (75 wt.-% of paraffin 35 wt.-% inhibitor component) Anionic surfactant 1.9 wt.-% Water 29.2 wt.-% Propanediol 21.6 wt.-% KOH 0.6 wt.-%

[0253] The amount of anionic surfactant relating to the paraffin inhibitor component (comprising polymer and organic solvent (see above)) was 4.0 wt.-%. The proportion of water/propanediol (wt./wt.) was 57:43.

EXAMPLE 3

Aqueous Dispersion of an Esterified Copolymer of Maleic Acid Anhydride and C.sub.20/24 Olefines (Paraffin Inhibitor Type (X1) in Solvesso 150 ND (Polymer/Solvent 60/40 wt/wt) Stabilized by 4 Wt.-% of Anionic Surfactant (25 wt.-% of Polymer in Dispersion)

Synthesis of the Paraffin Inhibitor Component

[0254] The synthesis was carried out as in example 1.

Preparation of an Aqueous Dispersion

[0255] In a first step, 62.4 g of melted paraffin inhibitor component were placed into a pre-heated reactor at 70 C. and 15.6 g of Solvesso150 ND were added, thereby obtaining a more diluted paraffin inhibitor component which comprises 60 wt.-% of the polymer and 40 wt.-% Solvesso 150 ND.

[0256] While stirring, 10.1 g of an aqueous solution of the anionic surfactant 1 (31 wt.-%) was added slowly, followed by 27.1 g of water and 22.6 g of 1,2-propanediol. After stirring for 15 min, a preheated (60 C.) solution of 0.8 g of solid KOH in 26.8 g of water and 19.6 g of 1,2-propanediol was added slowly and stirred for another 15 min.

[0257] Subsequently, the warm pre-emulsion was poured into a beaker of 200 ml, a stirring rod was added and kept at 60 C., in order to be treated with ultrasound using a Hielscher ultrasound generator UP400S (400 Watt, 24 kHz) with a Sonotrode H14 with a max. amplitude of 125 m. The tip of the ultrasound probe was immersed for 2 cm deep into the liquid and the magnetic stirrer engine was started ensuring a efficient homogenization. The pre-emulsion was treated at 50% power for 20 minutes and this resulted into a stable emulsion. After this time the stirrer was stopped and the warm emulsion was placed back in a reactor and cooled to RT under stirring over one hour. Afterwards it was filtered via a 125 m filter into a container. No coagulum was found. The final dispersion was obtained as a white opaque, slightly viscous liquid.

[0258] The resulting particle size of the dispersion D.sub.50 was monomodal at 160 nm.

[0259] The obtained dispersion comprises (the numbers relate to the total of all components of the aqueous dispersion):

TABLE-US-00005 Paraffin inhibitor component 42.2 wt.-% (polymer + org. solvent) polymer (60 wt.-% of paraffin 25.3 wt.-% inhibitor component) Anionic surfactant 1.7 wt.-% Water 32.9 wt.-% Propanediol 22,8 wt.-% KOH 0.4 wt.-%

[0260] The amount of anionic surfactant relating to the paraffin inhibitor (comprising polymer and organic solvent (see above)) was 4 wt.-%. The proportion of water/propanediol (wt./wt.) was 59:41.

EXAMPLE 4

Aqueous Dispersion of a Hyperbranched Polyester Modified with Terminal Behenyl Acid Groups (Paraffin Inhibitor Type (X6)) in Solvesso 150 ND (Polymer/Solvent 50/50 wt/wt) Stabilized by 4 wt.-% of Anionic Surfactant (23 wt.-% Polymer in the Dispersion).

Synthesis of the Paraffin Inhibitor Component

1.SUP.st .Step

[0261] In the first step, a hyperbranched polyester is produced. The reactor is purged with nitrogen. dimethylolproionic acid (DMPA, 375.48 g, 2.80 mol) and trimethylolpropane (TMP, 1.88 g, 0.014 mol), both in solid form, are first introduced to the reactor. 74.72 g (0.01868 mol) of polypropyleneglycol having an average molecular weight M.sub.n of 4000 g/mol and 1.44 g of methane sulfonic acid are premixed in a separate vessel and added to the reactor. Thereafter, the reactor is heated to 160 C. while stirring. Once the temperature reaches 130 C., the pressure is reduced to 250 to 500 mbar. The reaction is controlled via the acid-number value. The reactor is kept at 160 C. until the acid number was 22 mg KOH/g.

2.SUP.nd .Step

[0262] In the 2.sup.nd step, terminal OH-groups of the hyperbranched polyester are esterified with behenyl acid (technical mixture comprising as main components 85 to 90 wt. % of behenyl acid (linear C.sub.22 carboxylic acid), 10 wt. % of C.sub.20 carboxylic acid, and 5 wt. % C.sub.18 caboxylic acid). The temperature in the reactor is kept at 160 C. and 807.36 g (2.40 mol) of behenyl acid are added portionwise in solid form. The reaction is controlled via the acid-number value. After about 6 h, and acid number of 15 mg KOH/g is reached and the reaction is finished. Finally, the polymer at 160 C. is poured into the same amount of Solvesso 150 ND while stirring to achieve a paraffin inhibitor component, comprising 50% by weight of a paraffin inhibitor X5 and 50% by weight of Solvesso 150 ND having a melting point of 37 C. M.sub.w of the final polymer: 16000 g/mol.

Preparation of an Aqueous Dispersion

[0263] For the preparation of a stable oil/water emulsion 90.0 g of melted paraffin inhibitor component prepared as described above was placed into a pre-heated reactor at 65 C. While stirring, 11.25 g of an aqueous solution of the anionic surfactant 1 (31 wt.-%) was added slowly, followed by 48.1 g of water and 43.8 g of 1,2-propanediol.

[0264] After stirring for 15 min at 60 C., the warm pre-emulsion was poured into a beaker of 250 ml, a stirring rod was added and kept at 60 C., in order to be treated with ultrasound using a Hielscher ultrasound generator UP400S (400 Watt, 24 kHz) with a Sonotrode H14 with a max. amplitude of 125 m. The tip of the ultrasound probe was immersed for 2 cm deep into the liquid and the magnetic stirrer engine was started ensuring a efficient homogenization. The pre-emulsion was treated at 50% power for 10 minutes and this resulted into a stable emulsion which was cooled to RT under stirring over one hour. Afterwards it was filtered via a 125 m filter into a container. No coagulum was found. The final dispersion was obtained as a white opaque, viscous liquid.

[0265] The resulting particle size of the dispersion D.sub.50 was monomodal at 154 nm.

[0266] The obtained dispersion comprises (the numbers relate to the total of all components of the aqueous dispersion):

TABLE-US-00006 Paraffin inhibitor component 46.6 wt.-% (polymer + org. solvent) polymer (50 wt.-% of paraffin 23.3 wt.-% inhibitor component) Anionic surfactant 1.8 wt.-% Water 28.9 wt.-% ethylene glycole 22.7 wt.-%

EXAMPLE 5

Aqueous Dispersion of an Grafted EVA Polymer (Paraffin Inhibitor Type (X3) in Solvesso 150 ND and Shellsol D70 (Polymer/Solvent1/Solvent 2=50/25/25 wt/wt/Wt) Stabilized by 4 wt.-% of Anionic Surfactant (23 wt.-% of Polymer in Dispersion)

Synthesis of the Paraffin Inhibitor Component

[0267] A ethylene-vinylacetate copolymer (Escorene Ultra UL 02133EN2) (60.45 g) was dissolved in a high-boiling aliphatic hydrocarbon solvent (Shellsol D70) (144.3) and stearyl acrylate (246.48 g) with heating at 95 C. for about 30 to 60 min. After full dissolution of the ethylene-vinylacetate copolymer, the solution was cooled to 75 C. and tert-dodecylmercaptan (1.3656 g) was added to generate a ca. 70 wt % solution. After O.sub.2 removal via bubbling the monomer solution with N.sub.2 (30 min) a 9 wt. % solution of t-butylhydroperoxide in an organic solvent (7.633 g) was fed into the reaction solution with step-wise within 5 h. After adding the initiator, the reactor is heated to 90 C. and an additional amount of the 9 wt. % solution of t-butylhydroperoxide in an organic solvent (3.816 g) was fed into the reaction vessel over 1 h and left to stir for a further 1.5 h at 90 C. After the post-polymerisation period, a high-boiling aromatic hydrocarbon (Solvesso 150 ND) (154.66 g) and MEHQ (0.062 g, 100 ppm) were added to the reaction vessel, stirred for 30 min at 90 C. and the final product was cooled to room temperature under constant stirring. The final product comprises about 50 wt. % of the paraffin inhibitor (an EVA with polystearylarylate which is at least partly grafted the EVA) in Shellsol D70 (about 25 wt %) and Solvesso 150 ND (about 25 wt %).

Preparation of an Aqueous Dispersion

[0268] For the preparation of a stable oil/water emulsion 90.0 g of melted paraffin inhibitor component as described above was placed into a pre-heated reactor at 60 C. While stirring, 11.25 g of an aqueous solution of the anionic surfactant 1 (31 wt.-%) was added slowly, followed by 48.1 g of water and 43.8 g of 1,2-propanediol.

[0269] After stirring for 15 min at 55 C., the warm pre-emulsion was poured into a beaker of 250 ml, a stirring rod was added and kept at 55 C., in order to be treated with ultrasound using a Hielscher ultrasound generator UP400S (400 Watt, 24 kHz) with a Sonotrode H14 with a max. amplitude of 125 m. The tip of the ultrasound probe was immersed for 2 cm deep into the liquid and the magnetic stirrer engine was started ensuring a efficient homogenization. The pre-emulsion was treated at 50% power for 10 minutes and this resulted into a stable emulsion, which was cooled to RT under stirring over one hour and afterwards was filtered via a 125 m filter into a container. No coagulum was found. The final dispersion was obtained as a white opaque, slightly viscous liquid.

[0270] The resulting particle size of the dispersion D.sub.50 was monomodal at 331 nm.

[0271] The obtained dispersion comprises (the numbers relate to the total of all components of the aqueous dispersion):

TABLE-US-00007 Paraffin inhibitor component 46.6 wt.-% (polymer + org. solvent) polymer (50 wt.-% of paraffin 23.3 wt.-% inhibitor component) Anionic surfactant 1.8 wt.-% Water 28.9 wt.-% Propanediol 22.7 wt.-%

EXAMPLE 6

Aqueous Dispersion of a Copolymer of Ethylene and Ethylene Acetate EVA-2 (Paraffin Inhibitor Type X3) in Solvesso 150 ND (Polymer/Solvent 70/30 wt/wt) Stabilized by 4 wt.-% of Anionic Surfactant (30 wt.-% of Polymer in Dispersion)

(The Percentages Relate to the Total of all Components)

Synthesis of the Paraffin Inhibitor Component

[0272] An Ethylene-Vinyl Acetate copolymer with a vinyl acetate content of 30 wt. % and a melt viscosity @ 120 C.=ca. 70 mPas was prepared according to the examples in page 7 of WO 99/29748 A1.

Preparation of an Aqueous Dispersion

[0273] For the preparation of a stable oil/water emulsion 40 g of melted paraffin inhibitor component EVA-2 (X3) was placed into a pre-heated reactor at 65 C. and mixed with 17.10 g of Solvesso 150 ND. While stirring, 7.5 g of an aqueous solution of the anionic surfactant 1 (31 wt.-%) was added slowly, followed by 35.5 g of water and 33.0 g of ethylene glycol. This pre-emulsion was stirred for another 15 min at 60 C.

[0274] The pre-emulsion was poured into a beaker of 250 ml, a stirring rod was added and kept at 60 C., in order to be treated with ultrasound using a Hielscher ultrasound generator UP400S (400 Watt, 24 kHz) with a Sonotrode H14 with a max. amplitude of 125 m. The tip of the ultrasound probe was immersed for 2 cm deep into the liquid and the magnetic stirrer engine was started ensuring a efficient homogenization. The pre-emulsion was treated at 50% power for 10 minutes and this resulted into a stable emulsion which was cooled to RT under stirring over one hour. Afterwards it was filtered via a 125 m filter into a container. No coagulum was found. The final dispersion was obtained as a white opaque, viscous liquid.

[0275] The resulting particle size of the dispersion D.sub.50 was monomodal at 335 nm and had a solid content of 38.2%.

[0276] The obtained dispersion comprises (the numbers relate to the total of all components of the aqueous dispersion):

TABLE-US-00008 Paraffin inhibitor component 42.8 wt.-% (polymer + org. solvent) polymer (70 wt.-% of paraffin 30 wt.-% inhibitor component) Anionic surfactant 1.75 wt.-% Water 30.6 wt.-% Ethyleneglycol 24.85 wt.-%

[0277] The amount of anionic surfactant relating to the paraffin inhibitor component (comprising polymer and organic solvent (see above)) was 4.1 wt.-%. The proportion of water/ethanediol (wt./wt.) was 55:45.

COMPARATIVE EXAMPLE C1

Aqueous Dispersion of an Esterified Copolymer of Maleic Acid Anhydride and C.sub.20/24 Olefines (Paraffin Inhibitor Type (X1) in Solvesso 150 ND (Polymer/Solvent 75/25 wt/wt) Stabilized by a 4 wt. % of Non-Ionic Emulsifiers (25 wt. % Polymer)

[0278] Comparative Example C1 was carried out as example 1, except that the anionic surfactant 1 was substituted by a mix of the three non-ionic surfactants, non-ionic surfactant 1 (1.67 wt.-%), non-ionic surfactant 2 (1.67 wt.-%), and non-ionic surfactant 3 (0.67 wt.-%). A mixture of three non-ionic surfactants as suggested by WO 2018/104071 A1 was used. The final dispersion was obtained as a white opaque, slightly viscous liquid.

[0279] The resulting particle size of the dispersion D.sub.50 was monomodal 632 nm.

EXAMPLE C2

Aqueous Dispersion of an Esterified Copolymer of Maleic Acid Anhydride and C.sub.20/24 Olefines (Paraffin Inhibitor Type (X1) in Solvesso 150 ND (Polymer/Solvent 75/25 wt/wt) Stabilized by 7.5 wt. % of Non-Ionic Emulsifiers (25 wt. % Polymer)

[0280] Comparative Example C2 was carried out as example 1, except that the amount of anionic surfactant 1 was increased to 7.5 wt.-%.

[0281] The final dispersion was obtained as a white opaque, slightly viscous liquid.

[0282] The resulting particle size of the dispersion D.sub.50 was monomodal 265 nm.

Method B

Dispersion of Starting Materials in an Aqueous Phase Followed by Polymerization

EXAMPLE 7

Aqueous Dispersion of a Graft Polymer of an Ethylene-Vinylacetate Copolymer and Stearylacrylate (Paraffin Inhibitor (X3)) in Shellsol D70 (Polymer/Solvent 64/36 wt/wt) Stabilized by 6.5 wt.-% of Anionic Surfactant 1 (Polymer 27 wt.-%)

[0283] In a reactor, 15.0 g of the ethylene-vinyl acetate copolymer EVA-1 and 60.0 g of stearylacrylate were dissolved in 41.5 g of Shellsol D70 at 95 C. for one hour under a lean air atmosphere (5% O.sub.2) to obtain a clear solution.

[0284] For the preparation of a stable oil/water emulsion, the abovementioned solution was cooled down to 75 C. and 0.57 g of tert-dodecylmercaptane and a pre-warmed (50 C.) solution of 24.6 g of an aqueous solution of the anionic surfactant 1 (39 wt. %); 51.6 g of 1,2-propanediol and 48.1 g of water were added. The resulting pre-emulsion was treated in an Ultrasound equipment at 50% power as described in example 3 for 10 minutes while stirring, maintaining the temperature above 70 C. all the time. This resulted in a stable emulsion with a D50 droplet size of 272 nm.

[0285] The emulsion was transferred to a reactor equipped with an overhead stirrer, nitrogen inlet, thermometer, heating mantle, and syringe pump. The emulsion was brought to 60 C. and inerted under a nitrogen atmosphere. 22.2 g of tert-butyl hydroperoxide (10% solution in water) was added to the reactor. Subsequently, 12.0 g of a reducing agent on basis of sulfinic acid (Brggolit FF6M) (30% solution in water) was added via a syringe pump over a period of 2.5 hours to the reaction mixture at 60 C.

[0286] After the addition, the reaction mixture was continuously stirred by a mechanical stirrer and was maintained at 60 C. for one hour, then cooled to RT and filtered via a 125 m filter. No coagulum was found. The final dispersion was obtained as a white opaque, slightly viscous liquid.

[0287] The resulting particle size of the dispersion D.sub.50 was monomodal 215 nm, and the M.sub.w was 9040 g/mol (polydispersity M.sub.w/M.sub.n 4.6). The melting point of the paraffin inhibitor component is 8 C.

TABLE-US-00009 Paraffin inhibitor component 42.3 wt.-% (polymer + org. solvent) polymer (64.3 wt.-% of paraffin 27.2 wt.-% inhibitor component) Anionic surfactant 2.8 wt.-% Water 33.2 wt.-% Propanediol 18.7 wt.-% Initiator system 3.0 wt.-%

[0288] The amount of anionic surfactant relating to the PPD2 (comprising polymer and organic solvent (see above)) was 6.5 wt.-%. The proportion of water/propanediol (wt./wt.) was 59:41.

Application Tests

Stability of the Aqueous Dispersions

[0289] The stability of the dispersions was tested at three different temperatures: 20 C., room temperature (21 to 23 C.) and 50 C.

[0290] For determining the stability 20 ml of each dispersion were stored in glass bottles at the three different temperatures for at least 4 weeks. After said storage, the dispersions were visually inspected. It was checked whether they showed a separation or creaming/sedimentation. To quantify the stability of the dispersion the following criteria were developed:

TABLE-US-00010 1 Dispersion is stable and homogeneous. No creaming/sedimentation or separation can be observed. Dispersion is also fluid. No solidification or gelling. 2 Dispersion is stable with slight streaking formation. No creaming/sedimentation or separation can be observed. Dispersion is also fluid, but maybe more viscous. No solidification or gelling 3 Dispersion shows a separation. Creaming or sedimentation might be observed. Some dispersions do not flow any more. Some solid particles might be visible. 4 Dispersion solidified as a whole 5 Dispersion coagulated irreversibly

[0291] The results are summarized in the following table 1:

TABLE-US-00011 TABLE 1 Results of the stability tests Storage/ Stabil- Stability Stability Example weeks ity 20 C. RT 50 C. C1 4 w 1 3 3 C2 4 w 1 3 1 1 4 w 1 1 1 2 4 w 1 1 1 3 4 w 1 1 1 7 4 w 1 1 1

Comments

[0292] Whereas example 1-3 and 7 show no changes at any of the temperatures for at least 4 weeks, comparative examples C1 an C2 showed phase separation at at least one temperature. Phase separation can lead to blocking of lines and doesn't allow for homogeneous dosing, even when the product is still pumpable. Since, the active ingredient is in the oil phase, dosing the aqueous phase will result in no effect in respect to pour point reduction or reduction in paraffin crystallization, whereas dosing of the oil phase will lead to higher than required addition of additive, which in some cases might even be detrimental as well.

Pour Point Testing

[0293] The pour point and no flow point was determined with a Pour Point-Tester 45150 from PSL (Osterode am Harz, Germany). The pour point is measured according to ASTM D5985.

[0294] A 2 liter aluminum bottle containing the crude oil was heated to 80 C. for 30 minutes. During the heating process the bottle was shaken repeatedly to homogenize the crude oil. Then 50 ml of the crude oil were transferred to a 100 ml plastic bottle. The bottle was heated to 80 C. again for 15 minutes. After that, the dispersion containing 500 ppm of active PPD was added to the crude oil. Then the crude oil with the dispersion was shaken. Finally, the sample was heated to 80 C. again for 15 min. Approximately 30 ml of the sample were then transferred to the cup of the pour point tester so that it was filled up to the calibration line. The cup was inserted into the pour point tester, the sensor head was put into the sample and the measuring was started. The sample was firstly heated until 70 C. before the pour point measurement was started.

[0295] Several test were carried out varying the crude oils, whose origine and characteristics are describe in Table 2, the paraffin inhibitor (pour point depressant; PPD) type and the solution type used for the paraffin inhibitor. The results are summarized in Table 3.

TABLE-US-00012 TABLE 2 Description of the crude oils used for the application tests Pour Crude API Point WAT ( C.) oil type gravity ( C.) by DSC 1 32.21 21 45.47 2 36.75 24 50.97 3 36.8 24 51.55 4 44 <30 33.5 5 36.56 30 24.87 6 25.38 27 43.43 7 45.93 24 25.41 8 37.31 9 35.46 9 35.24 12 21.18

TABLE-US-00013 TABLE 3 Results of Pour point testing Paraffin Dosage, Active amount of Pour Non-Flow Table Crude oil inhibitor active active surfactant Solution type D.sub.50 particle Point Point entry type (PPD) type*** PPD (ppm) Anionic surfactant (wt. %*) of the PPD size (nm) ( C.) ( C.) 1 1 21 18 2 1 X1 500 Organic solvent- 15 13.6 based solution 3 1 X1.sup.a 500 Anionic surfactant 1 4 Aqueous dispersion 205 18 15.7 4 2 24 23 5 2 X3 500 Organic solvent- 18 15.8 based solution 7 2 X3.sup.b 500 Anionic surfactant 1 6.51 Aqueous dispersion 312 18 16.1 9 2 X3.sup.b 500 Anionic surfactant 1 6.51 Aqueous dispersion 309 18 15.3 10 2 X3 500 Organic solvent- 9 8.4 based solution 11 2 X3.sup.a 500 Anionic surfactant 1 4 Aqueous dispersion n.m.** 15 12.1 12 3 24 22.7 13 3 X6 500 Organic solvent- 15 13.6 based solution 14 3 X6.sup.a 500 Anionic surfactant 1 4 Aqueous dispersion 181 15 14.2 15 3 X2.sup.b 500 Anionic surfactant 1 6.51 Aqueous dispersion 169 18 16.9 *Relating to the amount of paraffin inhibitor component (paraffin inhibitor + optionally a hydrocarbon or a hydrocarbon mixture having a boiling point of at least 100 C.) **n.m. = not measured ***PPDs described under the same X-category were manufactured, for the purpose of testing, using the same monomers and ratio. This applies across Tables 3-5 and 8.

Cold Finger (Wax Inhibition) Testing

[0296] The cold finger deposition test is used to determine the wax inhibition properties of the dispersions. The wax inhibition was determined by exposing the crude oil to a cold metal finger surface in the presence and absence of the inhibitor. The amount and type of wax deposited on the cold metal finger was used to determine waxing tendency.

[0297] The test was started by conditioning the oil sample by heating to 80 C. and holding for 30 minutes to remove thermal history. A water bath on the cold finger apparatus was adjusted so that the oil temperature was maintained at 30 C. The cold finger was maintained at 15 C. and the cold finger was inserted into the oil sample. The test was run for 6 hours. The cold finger was removed, and the wax deposit on it was collected with a paper towel. The wax deposit was weighed. The wax test was repeated in the presence and absence of the inventive dispersion. The percent efficacy was calculated on the performance of paraffin inhibitor as compared to the baseline (i.e. the measurement without wax inhibitor).

[0298] Several test were carried out varying the crude oils used and varying the amount of Pour point depressant (PPD). The results are summarized in the following table:

TABLE-US-00014 TABLE 4 Results of wax inhibition testing Paraffin Dosage, Amount of Table Crude oil inhibitor active active surfactant Solution type D.sub.50 particle % wax entry type (PPD) type*** PPD (ppm) Anionic surfactant (wt. %*) of the PPD size (nm) inhibition 1 2 X1 500 46.36 2 2 X1.sup.a 500 Anionic surfactant 1 4 205 50.77 3 4 X1 100 Organic solvent-based 67 solution 4 4 X1.sup.a 100 Anionic surfactant 1 4 Aqueous dispersion 205 45 5 5 X1 150 Organic solvent-based 85 solution 6 5 X1.sup.a 150 Anionic surfactant 1 4 Aqueous dispersion 205 85 7 4 X2.sup.b 100 Anionic surfactant 1 6.51 Aqueous dispersion 169 34 8 6 X2.sup.b 120 Anionic surfactant 1 6.51 Aqueous dispersion 169 67 9 7 X2.sup.b 25 Anionic surfactant 1 6.51 Aqueous dispersion 169 86 10 8 X2.sup.b 25 Anionic surfactant 1 6.51 Aqueous dispersion 169 51 11 8 X2.sup.b 100 Anionic surfactant 1 6.51 Aqueous dispersion 169 94 12 5 X2.sup.b 25 Anionic surfactant 1 6.51 Aqueous dispersion 169 35 13 5 X2.sup.b 50 Anionic surfactant 1 6.51 Aqueous dispersion 169 28 14 5 X2.sup.b 100 Anionic surfactant 1 6.51 Aqueous dispersion 169 55 15 2 X3 500 Anionic surfactant 1 Organic solvent-based 1.74 solution 16 2 X3.sup.a 500 Anionic surfactant 1 4 Aqueous dispersion n.m.** 8.05 *Relating to the amount of paraffin inhibitor component (paraffin inhibitor + optionally a hydrocarbon or a hydrocarbon mixture having a boiling point of at least 100 C.) **n.m. = not measured ***PPDs described under the same X-category were manufactured, for the purpose of testing, using the same monomers and ratio. This applies across Tables 3-5 and 8. .sup.aPrepared by method A; .sup.bPrepared by method B

Yield Stress Testing

[0299] Stress-ramp tests were conducted to determine the amount of stress that must be applied to the sample before it begins to flow.

[0300] The test was started by conditioning the sample by homogenizing the crude oil at 10 C. above the WAT or 80 C., followed by heating the homogenized sample at 45 C. at a shear rate of 10 s.sup.1 for 10 minutes. Afterwards, the sample was cooled down. The sample was cooled from 45 C. to 5 C. at a rate of 1 C./min without shearing, followed by maintaining the sample at 5 C. for 16 h without shearing.

[0301] The prepared sample was tested at given temperature by applying a gradually increasing shear stress. The shear stress was increased from 1 to 850 Pa.

[0302] Tests were carried out to compare the yield points of a crude oil (entry 1, Table 5), of that crude oil mixed with an organic solvent-based solution of a paraffin inhibitor type X6 (entry 2, Table 5), and of that crude oil mixed with an aqueous dispersion of a paraffin inhibitor type X6 (entry 3, Table 5). The results are summarize in the following table:

TABLE-US-00015 TABLE 5 Results of yield stress testing Paraffin Dosage, Amount of Yield stress/ Table Crude oil inhibitor active active surfactant Solution type D.sub.50 particle yield point entry type (PPD) type** PPD (ppm) Anionic surfactant (wt. %*) of the PPD size (nm) (Pa) 1 2 >100 2 2 X6 500 Organic solvent-based 1 17 solution 3 2 X6.sup.a 500 Anionic surfactant 1 4 Aqueous dispersion 181 22 *Relating to the amount of paraffin inhibitor component (paraffin inhibitor + optionally a hydrocarbon or a hydrocarbon mixture having a boiling point of at least 100 C.) **PPDs described under the same X-category were manufactured, for the purpose of testing, using the same monomers and ratio. This applies across Tables 3-5 and 8. .sup.aPrepared by method A.

Cold Filter Plugging Point Testing

[0303] The cold filter plugging point (CFPP) is the lowest temperature at which a given volume of mineral oil still passes through a standardized filtration device in a specified time when cooled under certain conditions. This test gives an estimate for the lowest temperature that a oil will give trouble free flow in certain tubing systems. This is important as in cold temperate countries, a high cold filter plugging point will clog up tubes more easily.

[0304] The CFPP was measures according to the to the European Standard DIN EN 116. Two aqueous dispersions containing a different type of paraffin inhibitor were testes in two different mineral oils. The characteristics of the mineral oils used are summarized in Tables 6 and 7 and were measured according to the European Standard DIN EN 590. The CFPP results are summarized in Table 8.

TABLE-US-00016 TABLE 6 Characteristics of mineral oils used for the CFPP testing Mineral CP CFPP Viscosity (mm.sup.2/s @ Density @15 C. conductivity Pour Point no oil ( C.) ( C.) 15 C.) (kg/m3) (pS/m) ( C.) Flow ( C.) 1 9.4 10 3.7795 833 n.m.** 21 22.2 2 9.5 11 3.77 826.3 320 18 18.2 **n.m. = not measured

TABLE-US-00017 TABLE 7 Boiling analysis of mineral oils used for the CFPP testing. All values are given in C. Mineral oil IBP 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 1 172 188 195 201 207 213 219 226 233 240 247 254 262 270 279 289 2 167 183 190 195 202 208 215 222 230 238 247 256 265 275 285 296

TABLE-US-00018 TABLE 8 Results of CFPP testing Amount Paraffin Dosage, of active Table Mineral inhibitor active surfactant D.sub.50 particle CFPP entry oil (PPD)*** PPD (ppm) Anionic surfactant (wt. %*) size (nm) ( C.) 1 1 X4 150 Anionic surfactant 1 4 274 20 2 1 X5 90 Anionic surfactant 1 4 n.m.** 14 3 2 X4 150 Anionic surfactant 1 4 274 25 4 2 X5 180 Anionic surfactant 1 4 n.m.** 22 *Relating to the amount of paraffin inhibitor component (paraffin inhibitor + optionally a hydrocarbon or a hydrocarbon mixture having a boiling point of at least 100 C.) **n.m. = not measured ***PPDs described under the same X-category were manufactured, for the purpose of testing, using the same monomers and ratio. This applies across Tables 3-5 and 8.