Method of emulsion polymerization

Abstract

A method has been disclosed of preparing ultrafine hydrophobic latex particles of polymers and copolymers by free radical emulsion polymerization in a water-based system, making use therefor, in order to polymerize or copolymerize monomers or monomer mixtures respectively, of at least one compound selected from the group consisting of dimers and cobalt complexes, acting as a chain transfer agent (CTA), wherein said latex particles have an average particle size of less than 100 nm, being more than 10% lower than if prepared in the absence of said CTA, characterized in that said polymerization is conducted in a water-based reaction in the presence of a chain transfer agent and of a surfactant, wherein said surfactant is present in a concentration versus said monomer or monomer mixture of from 5 up to 25% by weight for a non-ionic surfactant or from 0.05 up to 10% by weight for an ionic surfactant, more particularly a surfactant in a concentration below twice its critical micelle concentration.

1 - 35 . (canceled)  
     
     
         36 . Free radical emulsion polymerization method for forming latex particles of a monomer or monomer mixture in a water-based reaction in the presence of a chain transfer agent and of a surfactant, wherein said surfactant is present in a concentration of at least 0.05%, by weight, versus said monomer to below twice its critical micelle concentration and that said chain transfer agent is a dimmer wherein said latex particle has an average particle size of less than 100 nm.  
     
     
         37 . Free radical emulsion polymerization method according to  claim 36 , wherein said dimer is selected from the group consisting of dimers or cross-dimers or α-methylstyrene, methyl methacrylate, hydroxy ethylacrylate, benzyl methacrylate, allyl methacrylate, methacrylonitrile, glycidyl methacrylate, methacrylic acid, tert.-butyl methacrylate, isocyanatoethyl methacrylate, meta-isopopenyl-α,α-dimethyl isocyanate (TMI), ω-sulfoxyalkyl methacrylates and alkali salts thereof.  
     
     
         38 . Free radical emulsion polymerization method according to  claim 36 , wherein said dimer is selected from the group consisting of α-methyl vinyl compounds and α-ethyl vinyl compounds.  
     
     
         39 . Free radical emulsion polymerization method according to  claim 36 , wherein said surfactant is an anionic surfactant, present in a concentration versus said monomer or monomer mixture of from 0.05 up to 5%, by weight.  
     
     
         40 . Free radical emulsion polymerization method according to  claim 39 , wherein said dimer is a compound selected from the group consisting of α-methyl vinyl compounds and α-ethyl vinyl compounds.  
     
     
         41 . Free radical emulsion polymerization method according to  claim 39 , wherein said dimer is a compound selected from the group consisting of dimers or cross-dimers or α-methylstyrene, methyl methacrylate, hydroxy ethylacrylate, benzyl methacrylate, allyl methacrylate, methacrylonitrile, glycidyl methacrylate, methacrylic acid, tert.-butyl methacrylate, isocyanatoethyl methacrylate, meta-isopopenyl-α,α-dimethyl isocyanate (TMI), ω-sulfoxyalkyl methacrylates and alkali salts thereof.  
     
     
         42 . Free radical emulsion polymerization method according to  claim 36 , wherein said monomers are selected from the group consisting of styrene derivatives, methacrylates, acrylates, methacrylamides, acrylamides, maleimides, vinyl ethers and vinyl esters.  
     
     
         43 . Free radical emulsion polymerization method according to  claim 42 , wherein said derivatives are selected from the group consisting of para-methylstyrene, tert.-butylstyrene, methylmethacrylate, ethylmethacrylate, butylmethacrylate, glycidylmethacryate, hydroxyethylmethacrylate, a-methylstyrene, ethylacrylate, butylacrylate, vinylacetate, vinyl versatate, butadiene, isoprene, acrylonitrile, methacrylonitrile, sulfoethyl methacrylate and its alkali salts, acrylic acid, methacrylic acid, tert-butyl acrylamide, AMPS, N-isopropylacrylamide, itaconic acid, maleic acid, maleic anhydride, vinylidene chloride, isopropylmethacrylate, dialkyl itaconate, acrylonitrile, methacrylonitrile and vinyl chloride.  
     
     
         44 . Free radical emulsion polymerization method according to  claim 39 , wherein said anionic surfactants are selected from the group consisting of fatty alcohol sulphates, alkylphenol sulphates, fatty alcohol ether sulphates, fatty alcohol ether sulphates, alkylphenol ether sulphates, alkylbenzene sulphonic acid, alkyl ether carboxylic acid and salts thereof, alkyl sulphosuccinates, alkyl sulphosuccinamates, phosphate esters or α-olefin sulphonates.  
     
     
         45 . Free radical emulsion polymerization method for forming latex particles of a monomer or monomer mixture in a water-based reaction in the presence of a chain transfer agent and of a surfactant, wherein said surfactant is present in a concentration below twice its critical micelle concentration of at least 0.05%, by weight, versus said monomer and that said chain transfer agent is a cobalt complex.  
     
     
         46 . Free radical emulsion polymerization method according to  claim 45 , wherein said anionic surfactants are selected from the group consisting of fatty alcohol sulphates, alkylphenol sulphates, fatty alcohol ether sulphates, fatty alcohol ether sulphates, alkylphenol ether sulphates, alkylbenzene sulphonic acid, alkyl ether carboxylic acid and salts thereof, alkyl sulphosuccinates, alkyl sulphosuccinamates, phosphate esters or α-olefin sulphonates.  
     
     
         47 . Free radical emulsion polymerization method according to  claim 45 , wherein said surfactant is an anionic surfactant, present in a concentration versus said monomer or monomer mixture of from 0.05 up to 1%, by weight.  
     
     
         48 . Free radical emulsion polymerization method according to  claim 45 , wherein said monomers are selected from the group consisting of styrene derivatives, methacrylates, acrylates, methacrylamides, acrylamides, maleimides, vinyl ethers and vinyl esters.  
     
     
         49 . Free radical emulsion polymerization method according to  claim 48 , wherein said derivatives are selected from the group consisting of para-methylstyrene, tert.-butylstyrene, methylmethacrylate, ethylmethacrylate, butylmethacrylate, glycidylmethacryate, hydroxyethylmethacrylate, a-methylstyrene, ethylacrylate, butylacrylate, vinylacetate, vinyl versatate, butadiene, isoprene, acrylonitrile, methacrylonitrile, sulfoethyl methacrylate and its alkali salts, acrylic acid, methacrylic acid, tert-butyl acrylamide, AMPS, N-isopropylacrylamide, itaconic acid, maleic acid, maleic anhydride, vinylidene chloride, isopropylmethacrylate, dialkyl itaconate, acrylonitrile, methacrylonitrile and vinyl chloride.  
     
     
         50 . Free radical emulsion polymerization method according to  claim 45 , wherein said cobalt complex is a cobalt II or cobalt III complex.  
     
     
         51 . Free radical emulsion polymerization method according to  claim 50 , wherein said cobalt complex is selected from cobalt II diphenyl complex; bis(borondifluorodiphenylglyoximate) cobaltate II complex; bis(borondifluorodimethylglyoximate) cobaltate II complex; [bis[m-(2,3-butanedione dioximato)(2-)O,O′tetraflorodiborato(2-propyl)N,N′,N″,N′″](2-propyl)Co(III)]] or benzylbis(dimethlglyximato)(pyridine)cobalt III.  
     
     
         52 . Free radical emulsion polymerization method according to  claim 36 , wherein said dimer is selected from the group consisting of α-methyl vinyl compounds and α-ethyl vinyl compounds.