Dispersions of acrylic polymer latex as additives for the inhibition of the deposition of paraffins in crude oils and compositions that contain them

A process for preparing a stable latex dispersion comprising:

• (1) 5 to 70 parts by weight of one or more (co)polymers, whose units come from:
• A—50 to 100%, by weight of one or more monomers of n-alkyl (meth)acrylate, with n designating the number of carbon atoms in the alkyl and being 6 to 40,
• B—0 to 50%, by weight of one or more (meth)acrylic or vinyl monomers having a water solubility of less than 5% at 20° C. selected from n-alkyl (meth)acrylates with n less than or equal to 6, 2-ethyl hexyl (meth)acrylate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl versatates, vinyl pivalate, vinyl laurate, and styrenes,
• C—0 to 50%, by weight of one or more polar monomers that are selected from (meth)acrylamides and their derivatives, N-methylolacrylamide, dialkylaminoethyl (meth)acrylates, the monoolefinic derivatives of sulfonic acid and phosphoric acid, acrylamidomethyl propane sulfonic acid, N-vinylpyrrolidone, vinylpyridine and its derivatives, and hydroxyalkyl (meth)acrylates,
• D—either 0 to 0.5% by weight of one or more monomers that are selected from ethylenically unsaturated monocarboxylic and/or dicarboxylic acids or anhydrides when C=0%,
• or up to 40% by weight of one or more monomers that are selected from ethylenically unsaturated monocarboxylic and/or dicarboxylic acids or anhydrides when C1 0%,
• (2) 0 to 30 parts by weight of a co-solvent or a mixture of co-solvents, parts by weight, selected from ketones, methylethylketone or methylisobutylketone, aromatic solvents, toluene, xylene and mixtures of aromatic hydrocarbons, alcohols, butanol or isopropanol, glycols and polyglycol ethers, ethylene or propylene glycol, diethylene glycol or dipropylene glycol,
• (3) 0.1 to 10, parts by weight of one or more surfactants (ionic surfactants and/or nonionic surfactants and/or protective colloids such as polyvinyl alcohols and/or amphiphilic polymers that are selected from sulfates or sulfonates of fatty alcohols or alkylphenol, alkylbenzene sulfonates and sulfosuccinates, quaternary ammonium salts, dimethyldialkylammonium chlorides and ethoxylated fatty alcohols),
• (4) water (sufficient quantity for 100),
• and surfactants with a low hydrophilic-lipophilic balance,
• and optionally other components comprising initiating agents, buffering agents, transfer agents, and
• said process comprising conducting radical-type emulsion polymerization in water of the monomers in the presence of said surfactant(s) (3) and optionally in the presence of one or more co-solvents, to form a dispersion, and adding to the resultant dispersion at least one additional surfactant, which is a non-ionic surfactant,
• and wherein the radical-type emulsion polymerization is optionally carried out in the presence of one or more co-solvents,
• wherein the at least one additional non-ionic surfactant is added to the dispersion while the dispersion is cooling.

A process for preparing a latex dispersion comprising:

• (1) 5 to 70 parts by weight of one or more (co)polymers, whose units come from:
• A—50 to 100%, by weight of one or more monomers of n-alkyl (meth)acrylate, with n designating the number of carbon atoms in the alkyl and being 6 to 40,
• B—0 to 50%, by weight of one or more (meth)acrylic or vinyl monomers having a water solubility of less than 5% at 20° C. selected from n-alkyl (meth)acrylates with n less than or equal to 6,2-ethyl hexyl (meth)acrylate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl versatates, vinyl pivalate, vinyl laurate, and styrenes,
• C—0 to 50%, by weight of one or more polar monomers that are selected from (meth)acrylamides and their derivatives, N-methylolacrylamide, dialkylaminoethyl (meth)acrylates, the monoolefinic derivatives of sulfonic acid and phosphoric acid, acrylamidomethyl propane sulfonic acid, N-vinylpyrrolidone, vinylpyridine and its derivatives, and hydroxyalkyl (meth)acrylates,
• D—either 0 to less than 0.5% by weight of one or more monomers that are selected from ethylenically unsaturated monocarboxylic and/or dicarboxylic acids or anhydrides when C=0%,
• or up to 40% by weight of one or more monomers that are selected from ethylenically unsaturated monocarboxylic and/or dicarboxylic acids or anhydrides when C≠0%,
• (2) 0 to 30 parts by weight of a co-solvent or a mixture of co-solvents, parts by weight, selected from ketones, methylethylketone or methylisobutylketone, aromatic solvents, toluene, xylene and mixtures of aromatic hydrocarbons, alcohols, butanol or isopropanol, glycols and polyglycol ethers, ethylene or propylene glycol, diethylene glycol or dipropylene glycol,
• (3) 0.1 to 10, parts by weight of one or more surfactants (ionic surfactants and/or nonionic surfactants and/or protective colloids such as polyvinyl alcohols and/or amphiphilic polymers that are selected from sulfates or sulfonates of fatty alcohols or alkylphenol, alkylbenzene sulfonates and sulfosuccinates, quaternary ammonium salts, dimethyldialkylammonium chlorides and ethoxylated fatty alcohols),
• (4) water (sufficient quantity for 100),
• and optionally other components comprising initiating agents, buffering agents, transfer agents and surfactants with a low hydrophilic-lipophilic balance,
• wherein at least one additional surfactant, which is a non-ionic surfactant, is optionally added to the dispersion after the dispersion is formed,
• said process comprising conducting radical-type emulsion polymerization in water of the monomers in the presence of surfactant(s) (3) and optionally in the presence of one or more co-solvents,
• wherein the polymerization is performed in the presence of at least one buffering agent and/or at least one transfer agent,
• wherein the stable latex dispersion is prepared free of an amount of acid or anhydride sufficient to interfere with the overall performance of the resultant latex dispersion and to limit the use thereof with at least one crude oil, and
• wherein the radical type emulsion polymerization is conducted in a single stage.