(EP2897936) 1. Aqueous organic peroxide emulsion composition devoid of protective colloid agent, namely a partially hydrolyzed polyvinyl acetate or cellulose derivatives, consisting of: - from 10% to 65% by weight of one or more organic peroxides, - from 2% to 25% by weight of at least one antifreeze agent, - from 0.01% to 10% by weight of an emulsifying agent, - optionally at least one additive, - water, the amount of which is determined so as to form the remainder of the composition up to 100%, characterized in that the emulsifying agent consists of a nonionic surfactant chosen exclusively from: - a triblock copolymer comprising at least one alkylene oxide block, wherein the copolymer consists of two alkylene oxide blocks surrounding a block of hydrophobic polymer, or of a block of alkylene oxide polymer surrounded by two blocks of hydrophobic polymer, said hydrophobic polymer being chosen from polyethylene and polypropylene, or - a triblock copolymer comprising: a first block consisting predominantly of ethylene oxide and to a minor extent of propylene oxide polymerized simultaneously or exclusively of polymerized ethylene oxide, a second block consisting predominantly of propylene oxide and to a minor extent of butylene oxide polymerized simultaneously or exclusively of polymerized propylene oxide, a third block having the same structure as the first or second block described above but being covalently bonded only to the block having a different composition, - an alkoxylated fatty alcohol; or - an alkoxylated fatty acid; or - an alkoxylated, hydrogenated or not, vegetable or animal oil; or - a mixture of several of these components. 2. Composition according to Claim 1, characterized in that the alkoxylated vegetable or animal oil is chosen from ethoxylated derivatives of mono-, di- or triglycerides and their mixtures. 3. Composition according to Claim 1 or 2, characterized in that the alkoxylated vegetable or animal oil comprises a mixture of: - ethoxylated glycerol connected or not to one or more chains of fatty acids, the latter being ethoxylated or not, - fatty acids ethoxylated on the acid functional group and/or on the hydroxyl functional group carried by the fatty acid chain, and also - variable proportions of fatty acids, of glycerol and of mono-, di- or triglycerides. 4. Composition according to any one of Claims 1 to 3, characterized in that the fatty alcohol comprises a chain of 4 to 60 and preferably 4 to 20 carbon atoms, linear or branched, cyclic or not, saturated or unsaturated, aromatic or not, and between 3 and 80 alkylene oxide units, preferably between 20 and 40. 5. Composition according to any one of the preceding claims, characterized in that the vegetable oil is ethoxylated or ethoxylated hydrogenated, such as, in particular, an ethoxylated castor oil or ethoxylated hydrogenated castor oil. 6. Composition according to Claim 1, characterized in that the fatty alcohol comprises a chain of 4 to 60 and preferably 4 to 20 carbon atoms, linear or branched, cyclic or not, saturated or unsaturated, aromatic or not, and between 3 and 80 alkylene oxide units, preferably between 20 and 40. 7. Composition according to Claim 1, characterized in that the block copolymer comprises at least two alkylene oxide blocks, said alkylene oxide block comprising between 5 and 80 units. 8. Composition according to Claim 6, characterized in that the alkylene oxide units are ethylene oxide units alone or ethylene oxide and propylene oxide and/or butylene oxide units. 9. Composition according to any one of the preceding claims, characterized in that the nonionic surfactant is present at a concentration of between 0.05% and 5% by weight in the emulsion, preferably of between 0.1% and 3% by weight. 10. Composition according to any one of the preceding claims, characterized in that it comprises more than 30% by weight of one or more organic peroxides, preferably more than 45% by weight. 11. Composition according to any one of the preceding claims, characterized in that the organic peroxide or peroxides are chosen from peroxyesters, peroxydicarbonates and/or diacyl peroxides. 12. Process for the preparation of the composition according to any one of the preceding claims, characterized in that it comprises the optionally successive steps of: - dispersion of the antifreeze agent, optionally at least said additive and also the emulsifying agent in water to obtain a homogeneous aqueous phase, then - the peroxide is added to the aqueous phase, and - the mixture thus formed is emulsified during an emulsion stage at a temperature of less than 5°C. 13. Use of the composition according to one of Claims 1 to 11 for the polymerization or the copolymerization of ethylenically unsaturated monomers. 14. Use according to Claim 13, characterized in that the ethylenically unsaturated monomers comprise vinyl chloride.
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