Method for preparing a composition comprising at least the mixture of at least one peroxydicarbonate and at least one peroxyester

Process according to any one of the preceding claims, characterized in that the peroxydicarbonate is chosen from the group consisting of di(2-ethylhexyl) peroxydicarbonate, di(sec-butyl) peroxydicarbonate, bis(1-methylheptyl) peroxydicarbonate, di(n-propyl) peroxydicarbonate, di(3-methoxybutyl) peroxydicarbonate, diethyl peroxydicarbonate and their mixtures.

Process according to any one of the preceding claims, characterized in that the peroxyester corresponds to the following general formula (II):

• in which formula (II) R3 and R4, which are identical or different, represent a linear, branched or cyclic C1-C20 alkyl group which can comprise, preferably be interrupted by, one or more heteroatoms, preferably one or more oxygen atoms, and/or be optionally substituted by one or more hydroxyl groups.

Process according to any one of the preceding claims, characterized in that the peroxyester is chosen from the group consisting of α-cumyl peroxyneodecanoate, α-cumyl peroxyneoheptanoate, 2,4,4-trimethylpent-2-yl peroxyneodecanoate, tert-butyl peroxy(n-heptanoate), tert-butyl peroxyneodecanoate, α-cumyl peroxy(n-heptanoate), tert-amyl peroxy(n-heptanoate), tert-butyl peroxyneoheptanoate, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, tert-amyl peroxy(2-ethylhexanoate), tert-butyl peroxy(2-ethylhexanoate), 1,1,3,3-tetramethylbutyl peroxy(2-ethylhexanoate), hydroxyperoxyesters, tert-amyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxypivalate, tert-hexyl peroxyneodecanoate, tert-hexyl peroxypivalate and their mixtures.

Process according to any one of the preceding claims, characterized in that the peroxyester is a hydroxyperoxyester chosen from the group consisting of 4-hydroxy-2-methylpentyl peroxyneodecanoate, 4-hydroxy-2-methylpentyl peroxyneoheptanoate, 4-hydroxy-2-methylpentyl peroxy(2-ethylhexanoate), 4-hydroxy-2-methylpentyl peroxy(2-phenylbutyrate), 4-hydroxy-2-methylpentyl peroxy(2-phenoxypropionate), 4-hydroxy-2-methylpentyl peroxy(2-butyloctanoate), 4-hydroxy-2-methylpentyl peroxyneohexanoate, 4-hydroxy-2-methylpentyl peroxyneotridecanoate, 4-hydroxy-2-methylhexyl peroxyneohexanoate, 4-hydroxy-2-methylhexyl peroxyneodecanoate, 5-hydroxy-1,3,3-trimethylcyclohexyl peroxyneodecanoate, 4-hydroxy-2,6-dimethyl-2,6-di(neohexanoylperoxy)heptane, 4-hydroxy-2,6-dimethyl-2,6-di(neodecanoylperoxy)heptane, 3-hydroxy-1,1-dimethylbutyl peroxy(2-ethylhexanoate), 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, 3-hydroxy-1,1-dimethylbutyl peroxyneoheptanoate and their mixtures, preferably 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate.

Process according to any one of the preceding claims, characterized in that the peroxyester is chosen from the group consisting of tert-butyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, α-cumyl peroxyneoheptanoate and hydroxyperoxyesters.

Process according to any one of the preceding claims, characterized in that it comprises the mixing of at least one peroxydicarbonate and of at least one peroxyester in an aqueous phase.

Process according to any one of the preceding claims, characterized in that the peroxydicarbonate and/or the peroxyester is (or are) diluted using at least one organic solvent or is (or are) in the aqueous emulsion form.

Process according to any one of the preceding claims, characterized in that it comprises the addition of at least one emulsifying agent, preferably chosen from the group consisting of cellulose ether derivatives, partially hydrolysed poly(vinyl acetates), non-ionic surfactants and their mixtures.

Process according to any one of the preceding claims, characterized in that the mixture is prepared at a temperature ranging from −10° C. to 50° C., preferably at a temperature ranging from 0° C. to 30° C.

Process according to any one of the preceding claims, characterized in that the mixture is prepared before injection of said composition into a polymerization reactor comprising one or more ethylenically unsaturated monomers.