Method for controlling the stability of emulsions

Abstract

The invention concerns a method for controlling the stability of an emulsion comprising a hydrophobic phase dispersed in an aqueous phase, or an aqueous phase dispersed in a hydrophobic phase, and less than 4% by weight of a surfactant, said process comprising the step of using in the emulsion a block copolymer.

1 - 23 . (canceled)  
   
   
       24 . A stabilized emulsion comprising: 
 a hydrophobic phase dispersed in an aqueous phase,    a surfactant in an amount of greater than 0 but less than 4% by weight, and    a linear block copolymer selected from the group consisting of: 
 (block A)-(block B) di-block copolymers,  
 (block A)-(block B)-(block A) tri-block copolymers, and  
 (block B)-(block A)-(block B) tri-block copolymers,  
 wherein  
 block A is a hydrophilic block,  
 block B is a hydrophobic block, and  
 block A and block B comprise units deriving from mono-alpha-ethylenically-unsaturated monomers.  
   
   
   
       25 . An emulsion according to  claim 24 , wherein the amount of surfactant is of less than 1% by weight  
   
   
       26 . A emulsion according to  claim 25 , wherein the amount if surfactants is of less than 0.1% by weight.  
   
   
       27 . An emulsion according to  claim 24 , having a weight ratio between the amount of the block polymer and the amount of the surfactant together with the block copolymer comprised between 50% and 1%.  
   
   
       28 . An emulsion according to  claim 24 , having less than 0.1% by weight of the block copolymer.  
   
   
       29 . An emulsion according to  claim 24 , wherein block B comprises repeating units deriving from monomers selected from the group consisting of: 
 alkylesters of an alpha-ethylenically-unsaturated, preferably mono-alpha-ethylenically-unsaturated, monocarboxylic acid,    vinyl Versatate,    acrylonitrile,    vinyl nitrites, comprising from 3 to 12 carbon atoms,    vinylamine amides, and    vinylaromatic compounds.    
   
   
       30 . An emulsion according to  claim 29 , wherein the alkylester of an alpha-ethylenically-unsaturated, is a mono-alpha-ethylenically-unsaturated, monocarboxylic acid.  
   
   
       31 . An emulsion according to  claim 29 , wherein block B comprises units deriving from monomers selected from the consisting of: 
 methylacrylate, ethylacrylate, n-propylacrylate, n-butylacrylate, methylmethacrylate, ethylmethacrylate, n-propylmethacrylate, n-butylmethacrylate, and 2-ethyl-hexyl acrylate, 2-ethyl-hexyl methacrylate, isooctyl acrylate, isooctyl methacrylate, lauryl acrylate, lauryl methacrylate, and    styrene.    
   
   
       32 . An emulsion according to  claim 24 , wherein block A comprises repeating units deriving from monomers selected from the group consisting of: 
 vinyl alcohol,    vinyl pyrrolidone,    polyethylene oxide (meth)acrylate (i.e. polyethoxylated (meth)acrylic acid), alpha ethylenically unsaturated monomers comprising a phosphate or phosphonate group,    alpha ethylenically unsaturated monocarboxylic acids,    amides of alpha ethylenically unsaturated monomers comprising a carboxylic group, alpha ethylenically unsaturated compounds comprising a sulphonic acid group, salts of alpha ethylenically unsaturated compounds comprising a sulphonic acid group, dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, ditertiobutylaminoethyl (meth)acrylate, dimethylaminomethyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide;    ethylenimine, vinylamine, 2-vinylpyridine, 4-vinylpyridine;    trimethylammonium ethyl (meth)acrylate chloride, trimethylammonium ethyl (meth)acrylate methyl sulphate, dimethylammonium ethyl (meth)acrylate benzyl chloride, 4-benzoylbenzyl dimethylammonium ethyl acrylate chloride, trimethyl ammonium ethyl (meth)acrylamido chloride, trimethyl ammonium propyl (meth)acrylamido chloride, vinylbenzyl trimethyl ammonium chloride, diallyldimethyl ammonium chloride,    monomers having the following formula:                        wherein:    R 1  is a hydrogen atom or a methyl or ethyl group;    R 2 , R 3 , R 4 , R 5  and R 6 , which are identical or different, are linear or branched C 1 -C 6 , preferably C 1 -C 4 , alkyl, hydroxyalkyl or aminoalkyl groups;    m is an integer from 1 to 10, for example 1;    n is an integer from 1 to 6, preferably 2 to 4;    Z represents a —C(O)O— or —C(O)NH— group or an oxygen atom;    A represents a (CH 2 ) p  group, p being an integer from 1 to 6, preferably from 2 to 4;    B represents a linear or branched C 2 -C 12 , advantageously C 3 -C 6 , polymethylene chain optionally interrupted by one or more heteroatoms or heterogroups, in particular O or NH, and optionally substituted by one or more hydroxyl or amino groups, preferably hydroxyl groups, and    X, which are identical or different, represent counterions, and their mixtures, and macromonomers deriving therefrom.      
   
   
       33 . An emulsion according to  claim 32 , wherein block A comprises units deriving from monomers selected from the group consisting of: 
 vinyl alcohol,    vinyl pyrrolidone,    acrylamide, methacrylamide,    polyethylene oxide (meth)acrylate,    hydroxyalkylesters of alpha-ethylenically-unsaturated, preferably mono-alpha-ethylenically-unsaturated, monocarboxylic acids,    hydroxyalkylamides of alpha-ethylenically-unsaturated, preferably mono-alpha-ethylenically-unsaturated, monocarboxylic acids,    dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, ditertiobutylaminoethyl (meth)acrylate, dimethylaminomethyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide,    ethylenimine, vinylamine, 2-vinylpyridine, 4-vinylpyridine,    trimethylammonium ethyl (meth)acrylate chloride, trimethylammonium ethyl (meth)acrylate methyl sulphate, dimethylammonium ethyl (meth)acrylate benzyl chloride, 4-benzoylbenzyl dimethylammonium ethyl acrylate chloride, trimethyl ammonium ethyl (meth)acrylamido chloride, trimethylammonium ethyl (meth)acrylate methyl sulphate, trimethyl ammonium propyl (meth)acrylamido chloride, vinylbenzyl trimethyl ammonium chloride,    diallyldimethyl ammonium chloride,    alpha-ethylenically-unsaturated, preferably mono-alpha-ethylenically-unsaturated, monomers comprising a phosphate or phosphonate group,    alpha-ethylenically-unsaturated, preferably mono-alpha-ethylenically-unsaturated, monocarboxylic acids,    monoalkylesters of alpha-ethylenically-unsaturated, preferably mono-alpha-ethylenically-unsaturated, dicarboxylic acids,    monoalkylamides of alpha-ethylenically-unsaturated, preferably mono-alpha-ethylenically-unsaturated, dicarboxylic acids,    alpha-ethylenically-unsaturated, preferably mono-alpha-ethylenically-unsaturated, compounds comprising a sulphonic acid group, and salts of alpha-ethylenically-unsaturated, preferably mono-alpha-ethylenically-unsaturated, compounds comprising a sulphonic acid group.    
   
   
       34 . An emulsion according to  claim 32 , wherein block A comprises units deriving from monomers selected from the group consisting of: 
 2-hydroxyethylacrylate,    acrylic acid, methacrylic acid,    vinyl sulphonic acid, salts of vinyl sulfonic acid, vinylbenzene sulphonic acid, salts of vinylbenzene sulphonic acid, alpha-acrylamidomethylpropanesulphonic acid, salts of alpha-acrylamidomethylpropanesulphonic acid 2-sulphoethyl methacrylate, salts of 2-sulphoethyl methacrylate, acrylamido-2-methylpropanesulphonic acid (AMPS), salts of acrylamido-2-methylpropanesulphonic acid, and styrenesulfonate (SS).    
   
   
       35 . An emulsion according to  claim 24 , wherein the block copolymer is a di-block copolymer, block A being a poly(acrylic acid) block, or a salt thereof, and block B being a poly (butylacrylate) block.  
   
   
       36 . An emulsion according to  claim 24 , wherein the surfactant is a nonionic, anionic, cationic, or amphoteric surfactant.  
   
   
       37 . An emulsion according to  claim 36 , wherein block A is polyanionic in the pH conditions of the emulsion, and wherein the surfactant is not cationic in the pH conditions of the emulsion.  
   
   
       38 . An emulsion according to  claim 24 , wherein the emulsion: 
 is a pre-emulsion, used for latex polymerization, and    the hydrophobic phase is a latex monomer phase comprising ethylenically-unsaturated monomers.    
   
   
       39 . An emulsion according to  claim 38 , wherein the ethylenically unsaturated of the latex monomer phase monomers are selected from the group consisting of alkylacrylates, alkylmethacrylates, vinylacetate, styrene, butadiene, derivatives thereof, and mixtures thereof.  
   
   
       40 . An emulsion according to  claim 39 , wherein the latex monomer phase comprises a mixture of monomers comprising ethyl-hexyl acrylate, vinyl acetate, and acrylic acid oligomers comprising at least one ethylenically unsaturated group.  
   
   
       41 . An emulsion according to  claim 38 , wherein the block copolymer is a di-block copolymer, block A being a poly(acrylic acid) block, or a salt thereof, and block B being a poly(butylacrylate) block.  
   
   
       42 . An emulsion according to  claim 38 , wherein the ratio between the weight-average molecular weight of the hydrophilic block(s) and the weight-average molecular weight of the hydrophobic block(s) is of from 2.33 to 9, and the weight-average molecular weight of the copolymer is comprised between 2000 g/mol and 15000 g/mol.