AQUEOUS COMPOSITION IN THE FORM OF AN EMULSION COMPRISING AT LEAST ONE PEROXYDICARBONATE AND AT LEAST ONE PEROXYESTER

Description

[0001] The present invention relates to an aqueous composition in the form of an emulsion comprising at least one peroxydicarbonate and at least one hydroxyperoxyester.

[0002] The invention also relates to the use of an aqueous composition comprising the mixture of organic peroxides, as defined above, for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, preferably halogenated, and more preferably vinyl chloride.

[0003] Organic peroxides, in liquid or solid form, are commonly used as polymerization initiators of ethylenically unsaturated monomers for the synthesis of different types of polymers.

[0004] However, their implementation frequently poses a number of problems. Indeed, organic peroxides are most often highly unstable species because they decompose relatively easily under the action of a low input of heat, mechanical energy (friction or shock) or incompatible contaminants. Thus, in the event of an uncontrolled rise in their storage temperature, certain organic peroxides can undergo self-accelerated exothermic decomposition which can lead to fires and / or violent explosions. In addition, under these conditions, some of these organic peroxides can release combustible vapors which can react with any source of ignition which can drastically increase, or even accelerate, the risks of violent explosion. It follows that it is important to take adequate safety precautions during the storage and transport of organic peroxides.

[0005] To overcome these drawbacks, organic peroxides are packaged in the form of aqueous emulsions containing antifreezes. Thus, the presence of water allows both the absorption and dissipation of the energy generated in the event of exothermic decomposition of organic peroxides, while the role of the antifreeze is to maintain the emulsion in liquid form at temperatures below -10°C, generally below -15°C, which limits the risks of involuntary exothermic decomposition of organic peroxides.

[0006] Aqueous emulsions generally also contain an emulsifier which has the advantage of lowering the interfacial tension between the aqueous phase and the organic peroxide in order to facilitate its dispersion in the form of droplets and to maintain the size of the latter over time. Indeed, over time, the peroxide droplets can agglomerate together causing an increase in their average size and their maximum size which can lead, in certain cases, to a total or partial phase separation and, consequently, to an overall destabilization of the emulsion.

[0007] In view of the above, aqueous emulsions of organic peroxide must therefore be stable for safety reasons not only during their production but also over a relatively long period corresponding to their transport and storage before being used as polymerization initiators. To achieve this, the organic peroxide droplets must mainly have a small average size and a maximum size that are stable over time.

[0008] Furthermore, it is essential to obtain homogeneous emulsions. Indeed, the use of non-homogeneous organic peroxide emulsions, i.e. having a significant difference in organic peroxide concentration distributed between the upper and lower part of the aqueous phase, can also cause unpredictable differences in initiator concentrations in the polymerization reactor.

[0009] Furthermore, the steps of unloading the emulsion into intermediate storage silos, pumping and introducing an organic peroxide emulsion into a polymerization reactor are important steps for the quality of the resulting polymer and the reliability of the polymerization process. These handling steps must be carried out as quickly as possible. To achieve this, it is important that the peroxide emulsion has a low viscosity so that the flow of the emulsion is facilitated as much as possible. Thus, an organic peroxide emulsion must have a maximum dynamic viscosity of around 500-700 mPa.s at low temperature, typically around -10°C for a shear rate of 100 s -1< . Dynamic viscosity measurements are carried out using coaxial cylinders that create the shear, for example according to DIN 53019.

[0010] However, the person skilled in the art knows that, for this type of emulsion, seeking to reduce the size of the droplets contributes to increasing the viscosity (see paragraph 1.4 of the article by JP Canselier and M.Poux, “Emulsification processes - Mechanism of emulsion formation” Techniques de l'Ingénieur J2 152, pp 1-12, publication of June 10, 2004).

[0011] More specifically, seeking to reduce the size of organic peroxide droplets and, at the same time, reducing the viscosity of organic peroxide emulsions leads to contradictory effects that are difficult to reconcile.

[0012] In order to address all of these issues, aqueous emulsions of organic peroxides have already been developed in the prior art, comprising at least one organic peroxide, at least one particular non-ionic surfactant, as an emulsifying agent, for example an alkoxylated fatty alcohol and / or an optionally hydrogenated alkoxylated vegetable or animal oil, and antifreeze agents, such as alcohols, in particular methanol.

[0013] However, such aqueous emulsions of organic peroxides have not proven to be sufficiently stable over time. Indeed, it has been observed that the average size as well as the maximum size of the peroxide droplets increased significantly over a relatively short period of time, leading, in some cases, to a complete phase separation of the emulsion. Some of these emulsions, for example, have become unstable in less than 6 months, or even in less than 3 months, at temperatures of the order of -20°C or -25°C, which naturally makes their transport and storage difficult to undertake safely.

[0014] Thus, one of the objectives of the present invention is to propose a composition in the form of an aqueous emulsion of organic peroxide which is stable and homogeneous over time, intended to be used as polymerization initiators, which does not have the drawbacks previously described in terms of safety and quality of the product obtained.

[0015] In particular, one of the aims of the present invention is to provide an aqueous emulsion composition of organic peroxide having in particular a small average droplet size, in particular less than 10 µm, preferably less than 5 µm, a homogeneous size distribution, a homogeneous distribution of the organic peroxide and a maximum droplet size of less than 20 µm, or even less than 15 µm, in particular less than 5 µm, stable over time, for example over a period of six months, while respecting the required conditions in terms of viscosity and flow time of the emulsion.

[0016] The present invention therefore relates in particular to an aqueous emulsion composition of organic peroxide comprising: one or more organic peroxides of formula (I):

[0017] Formula (I) in which R 1< and R 2<, identical or different, represent a C 1 -C 20 alkyl group, linear, branched or cyclic, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms; one or more organic peroxides of formula (II):

[0018] Formula (II) in which R 3< and R 4<, identical or different, represent a linear, branched or cyclic C 1 -C 20 alkyl group, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms, and / or optionally substituted by one or more hydroxyl groups, said organic peroxide of formula (II) being a hydroxyperoxyester or at least one of said organic peroxides of formula (II) being a hydroxyperoxyester.

[0019] The composition according to the invention thus has the advantage of being stable for a period of 6 months at a temperature of around -20°C or -25°C.

[0020] In particular, the composition according to the invention is an aqueous emulsion having in particular a small average droplet size, preferably less than 10 µm, preferably less than 5 µm, a homogeneous size distribution, a homogeneous distribution of the organic peroxide and a maximum droplet size of less than 20 µm, or even less than 15 µm, which are stable over time, without the appearance of gel or phase separation in the organic and aqueous phases.

[0021] More specifically, the composition according to the invention has an average droplet size (d 50 ) of less than 10 µm after production or during storage at a temperature of -20°C for a period of six months; the maximum droplet size (d 100 ) not exceeding 20 µm during this period.

[0022] Furthermore, the composition according to the invention has the advantage of being stable for a period of 6 months at a temperature of around -20°C or -25°C.

[0023] By "homogeneous" is meant that the organic peroxides have a low concentration gradient. In other words, the samples taken from different locations in the emulsion have a similar concentration of organic peroxides (i.e., preferably have less than 5% absolute difference, preferably less than 3% absolute difference, more preferably less than 2% absolute difference). Thus, advantageously, when the composition according to the invention is packaged in a storage container, the difference in organic peroxide concentration distributed between the upper part and the lower part of the container remains less than 3%, or even less than 2%, over time, in particular over a period of 6 months, which makes it possible to guarantee the reproducibility of the polymerization rates.

[0024] This thus makes it possible to take the composition according to the invention both from the upper part and from the lower part of the container in order to initiate the polymerization of the ethylenically unsaturated monomers at similar and reproducible speeds.

[0025] As a result, the composition according to the invention remains effective over time.

[0026] In addition, the composition according to the invention has a low viscosity, preferably less than 850 mPa.s, preferably less than 700 mPa.s, even more preferably less than 500 mPa.s, which allows a very short flow time.

[0027] Dynamic viscosity measurements can be performed using coaxial cylinders that create shear, for example according to DIN 53019.

[0028] Thus, the composition according to the invention can be transported and stored safely in polymer production units and lead to good quality polymeric materials.

[0029] For clarification, the composition according to the invention makes it possible to improve the transparency of the final polymeric material.

[0030] The invention also relates to the use of an aqueous composition comprising the mixture of organic peroxides, as defined above, for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, in particular vinyl monomers, preferably halogenated, and more preferably vinyl chloride.

[0031] The aqueous composition comprising the mixture of organic peroxides can therefore be used as polymerization initiators for the synthesis of polymers or copolymers obtained from one or more ethylenically unsaturated monomers.

[0032] Thus the composition is compatible with the polymerization or copolymerization of ethylenically unsaturated monomers, preferably vinyl monomers.

[0033] Furthermore, the invention also relates to a halogenated vinyl polymer obtained by polymerization of at least one halogenated ethylenically unsaturated monomer in the presence of the aqueous composition containing the mixture of organic peroxides as defined above.

[0034] Other characteristics and advantages of the invention will appear more clearly on reading the description and examples which follow.

[0035] In what follows, and unless otherwise indicated, the limits of a domain of values ​​are included in this domain.

[0036] The expression "at least one" is equivalent to the expression "one or more". Composition

[0037] As indicated previously, the composition according to the invention comprises one or more organic peroxides of formula (I):

[0038] Formula (I) in which R 1< and R 2< , identical or different, represent a C 1 -C 20 alkyl group, linear, branched or cyclic, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms.

[0039] Preferably, R 1< and R 2< , identical or different, represent a C 1 -C 16 alkyl group, more preferably C 3 -C 12 , in particular C 3 -C 10 , linear, branched or cyclic, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms.

[0040] Preferably, R 1< and R 2< , identical or different, represent a linear C 1 -C 16 alkyl group, more preferably C 3 -C 12 , in particular C 3 -C 10 , which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms.

[0041] Preferably, R 1< and R 2< , identical or different, represent a C 1 -C 16 alkyl group, more preferably C 3 -C 12 , in particular C 3 -C 10 , branched, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms.

[0042] Preferably, R 1< and R 2< , identical or different, represent a C 3 -C 16 alkyl group, more preferably C 3 -C 12 , in particular C 3 -C 10 , cyclic, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms.

[0043] For the purposes of the present invention, the term “cyclic alkyl group” means that the alkyl group comprises a cycle, preferably aromatic, comprising 5 to 6 links.

[0044] Preferably, the heteroatom is an oxygen atom.

[0045] Preferably, R 1< and R 2< are identical and represent a C 2 -C 16 alkyl group, in particular C 3 -C 12 , even more preferably C 3 -C 10 , linear or branched, preferably branched.

[0046] Preferably, R 1< and R 2< are identical and represent a C 2 -C 8 alkyl group, linear or branched, preferably branched.

[0047] The organic peroxides of formula (I) are preferably selected from the group consisting of di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, bis(1-methylheptyl) peroxydicarbonate, di-n-propylperoxydicarbonate, di(3-methoxybutyl)peroxydicarbonate, diethyl peroxycarbonate and mixtures thereof, preferably di(2-ethylhexyl) peroxydicarbonate and di-sec-butyl peroxydicarbonate.

[0048] Advantageously, the organic peroxide of formula (I) is chosen from the group consisting of di(2-ethylhexyl) peroxydicarbonate sold under the trade name Luperox ®< 223 and di-sec-butyl peroxydicarbonate sold under the trade name Luperox ®< 225.

[0049] As indicated previously, the composition according to the invention further comprises one or more organic peroxides of formula (II):

[0050] Formula (II) in which R 3< and R 4<, identical or different, represent a linear, branched or cyclic C 1 -C 20 alkyl group, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms, and / or optionally substituted by one or more hydroxyl groups, said organic peroxide of formula (II) being a hydroxyperoxyester or at least one of said organic peroxides of formula (II) being a hydroxyperoxyester.

[0051] Preferably, R 3< and R 4<, identical or different, represent a C 7 -C 20 alkyl group, preferably C 7 -C 16 , in particular C 7 -C 10 , linear or branched, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms, and / or optionally substituted by one or more hydroxyl groups.

[0052] Preferably, R 3< and R 4<, identical or different, represent a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular C 7 -C 10 , linear, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms, and / or optionally substituted by one or more hydroxyl groups.

[0053] Preferably, R 3< and R 4<, identical or different, represent a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular C 7 -C 10 , branched, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms, and / or optionally substituted by one or more hydroxyl groups.

[0054] Preferably, R 3< and R 4<, identical or different, represent a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular C 7 -C 10 , cyclic, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms, and / or optionally substituted by one or more hydroxyl groups.

[0055] For the purposes of the present invention, the term “cyclic alkyl group” means a linear or branched alkyl group, further comprising a cycle, preferably aromatic, preferably comprising 5 to 6 links.

[0056] In other words, within the meaning of the present invention, a cyclic alkyl group is understood to comprise a linear or branched alkyl group, preferably C 2 -C 4 , and a cycle, preferably aromatic, preferably comprising 5 to 6 members.

[0057] Preferably, the cyclic alkyl group comprises a branched alkyl group, preferably C 2 -C 4 , and an aromatic ring preferably comprising 5 to 6 links.

[0058] Preferably, R 3< and R 4<, identical or different, represent an alkyl group, as defined above, which may be interrupted by one or more heteroatoms, preferably one or more oxygen atoms, and / or optionally substituted by one or more hydroxyl groups.

[0059] Preferably, R 3< and R 4<, identical or different, represent a linear, branched or cyclic C 1 -C 20 alkyl group, which may optionally be substituted by one or more hydroxyl groups.

[0060] Preferably, R 3< represents a linear or branched C 7 -C 20 alkyl group, preferably C 7 -C 16 , in particular C 7 -C 10 , which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms, and R 4< represents a linear or branched C 1 -C 7 alkyl group, preferably C 2 -C 6 , optionally substituted by one or more hydroxyl groups, or a cyclic C 7 -C 16 alkyl group, in particular C 7 -C 10 .

[0061] Preferably, R 3< represents a C 7 -C 20 alkyl group, preferably C 7 -C 16 , in particular C 7 -C 10 , branched, which may comprise, preferably interrupted by, one or more heteroatoms, preferably one or more oxygen atoms, and R 4< represents a C 1 -C 7 alkyl group, preferably C 2 -C 6 , branched, optionally substituted by one or more hydroxyl groups.

[0062] Preferably, the heteroatom is an oxygen atom.

[0063] Preferably, in formula (II): R 3< represents a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular a C 7 -C 10 alkyl group, linear, branched or cyclic, preferably branched, which may be interrupted by one or more oxygen atoms, preferably an oxygen atom; R 4< represents: i) a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular a C 7 -C 10 alkyl group, linear or branched, preferably branched, which may be interrupted by one or more oxygen atoms, preferably an oxygen atom;ii) a linear or branched, preferably branched, C 1 -C 7 alkyl group, preferably C 2 -C 6 , optionally substituted by one or more hydroxyl groups, or iii) a cyclic, in particular C 9 , cyclic, C 7 -C 10 alkyl group. Preferably, in formula (II), R 3< represents a linear or branched, preferably branched, C 7 -C 16 alkyl group, in particular C 7 -C 10 alkyl group. ;

[0064] Preferably, in formula (II), R 4< represents: a C 1 -C 7 alkyl group, preferably C 2 -C 6 , in particular C 4 or C 6 , linear or branched, preferably branched, optionally substituted by one or more hydroxyl groups, a C 7 -C 10 alkyl group, in particular C 9 , cyclic.

[0065] Preferably, in formula (II), when R 4< represents a cyclic C 7 -C 10 alkyl group, R 4< then comprises a linear or branched, preferably branched, C 2 -C 4 alkyl group, in particular C 3 , and a cycle, preferably aromatic, preferably comprising 5 to 6 links

[0066] Even more preferably, R 4< represents a C 1 -C 7 alkyl group, preferably C 2 -C 6 , in particular C 6 , linear or branched, preferably branched, substituted by one or more hydroxyl groups, in particular a hydroxyl group.

[0067] Advantageously, in formula (II): R 3< represents a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular a C 7 -C 10 alkyl group, linear or branched, preferably branched, R 4< represents a C 1 -C 7 alkyl group, preferably a C 2 -C 6 alkyl group, linear or branched, preferably branched, optionally substituted by one or more hydroxyl groups.

[0068] The organic peroxides of formula (II) are preferably selected from the group consisting of alpha-cumyl peroxyneodecanoate, alpha-cumyl peroxyneoheptanoate, 2,4,4 trimethylpentyl-2-peroxyneodecanoate, tert-butyl peroxy n-heptanoate, tert-butyl peroxyneodecanoate, alpha-cumyl peroxy n-heptanoate, tert-amyl peroxy n-heptanoate, tert-butyl peroxyneoheptanoate, 2,5-dimethyl-2,5 di (2-ethylhexanoyl peroxy) hexane, tert-amyl peroxy 2-ethylhexanoate, tert-butyl peroxy 2-ethylhexanoate, 1,1,3,3 tetramethyl butyl-peroxy-2 ethylhexanoate, hydroxyperoxyesters, tert-amyl peroxy neodecanoate, 1,1,3,3 tetramethyl butyl-peroxy neodecanoate, 1,1,3,3 tetramethyl butyl-peroxy pivalate, tert-hexyl peroxyneodecanoate, tert-hexyl peroxypivalate and mixtures thereof.

[0069] Preferably, the peroxyesters are selected from the group consisting of hydroxyperoxyesters.

[0070] The hydroxyperoxyesters are advantageously chosen from the group consisting of 4-hydroxy-2-methylpentylperoxyneodecanoate, 4-hydroxy-2-methylpentylperoxyneoheptanoate, 4-hydroxy-2-methylpentylperoxy-(2-ethylhexanoate), 4-hydroxy-2-methylpentylperoxy-2-phenylbutyrate, 4-hydroxy-2-methylpentylperoxy-2-phenoxypropionate, 4-hydroxy-2-methylpentylperoxy-(2-butyloctanoate), 4-hydroxy-2-methylpentylperoxyneohexanoate, 4-hydroxy-2-methylpentylperoxyneotridecanoate, 4-hydroxy-2-methylhexylperoxyneohexanoate, 4-hydroxy-2-methylhexylperoxyneodecanoate, 5-hydroxy-1,3,3-trimethylcyclohexylperoxyneodecanoate, 4-hydroxy-2,6-dimethyl-2,6-di(neohexanoylperoxy)heptane, 4-hydroxy-2,6-dimethyl-2,6-di(neodecanoylperoxy)heptane, 3-hydroxy-1,1 dimethylbutylperoxy 2-ethylhexanoate, 3-hydroxy-1,1 dimethylbutyl peroxyneodecanoate, 3-hydroxy-1,1 dimethylbutyl peroxyneoheptanoate and mixtures thereof, preferably 3-hydroxy-1,1 dimethylbutyl peroxyneodecanoate.

[0071] Preferably, the organic peroxide of formula (II) is selected from the group consisting of tert-butyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, alpha-cumyl peroxyneoheptanoate, hydroxyperoxyesters and mixtures thereof.

[0072] Preferably, the organic peroxide of formula (II) is chosen from the group consisting of 3-hydroxy-1,1 dimethylbutyl peroxyneodecanoate, sold under the trade name Luperox ®< 610 by Arkema, alpha-cumyl peroxyneoheptanoate, sold under the trade name Luperox ®< 188, tert-amyl peroxyneodecanoate sold under the trade name Luperox ®< 546 and tert-butyl peroxyneodecanoate sold under the trade name Luperox ®< 10 by Arkema, and mixtures thereof.

[0073] Preferably, the organic peroxide of formula (II) is chosen from the group consisting of 3-hydroxy-1,1 dimethylbutyl peroxyneodecanoate, sold under the name Luperox ®< 610 by Arkema, tert-butyl peroxyneodecanoate sold under the name Luperox ®< 10 by Arkema and their mixtures.

[0074] Advantageously, the organic peroxide of formula (II) is 3-hydroxy-1,1 dimethylbutyl peroxyneodecanoate sold under the trade name Luperox ®< 610 by Arkema.

[0075] The organic peroxide(s) of formula (I) and the organic peroxide(s) of formula (II) are present in a concentration ranging from 40 to 70% by weight relative to the total weight of the composition, preferably ranging from 40 to 65% by weight relative to the total weight of the composition, more preferably present in a concentration ranging from 40 to 60% by weight relative to the total weight of the composition. In other words, the concentration of the organic peroxide(s) of formula (I) plus the concentration of the organic peroxide(s) of formula (II) represent a concentration ranging from 40 to 70% by weight relative to the total weight of the composition, preferably ranging from 40 to 65% by weight relative to the total weight of the composition, more preferably ranging from 40 to 60% by weight relative to the total weight of the composition.

[0076] Preferably, the total concentration of organic peroxides in the composition ranges from 40 to 70% by weight relative to the total weight of the composition, preferably from 40 to 65% by weight relative to the total weight of the composition, more preferably from 40 to 60% by weight.

[0077] Preferably, only organic peroxides of formulas (I) and (II) are present in the composition.

[0078] Preferably, the weight ratio of organic peroxide(s) of formula (I) / organic peroxide(s) of formula (II) varies from 1 / 99 to 99 / 1, preferably from 2 / 98 to 98 / 2.

[0079] According to another embodiment, the weight ratio of organic peroxide(s) of formula (I) / organic peroxide(s) of formula (II) varies from 10 / 90, in particular from 20 / 80, to 50 / 50.

[0080] According to another embodiment, the weight ratio of organic peroxide(s) of formula (I) / organic peroxide(s) of formula (II) varies from 99 / 1, in particular 97 / 3, in particular 90 / 10 and preferably 80 / 20 to 50 / 50.

[0081] The organic peroxides of formulae (I) and (II) advantageously have a one-hour half-life temperature of less than or equal to 90°C, preferably less than 90°C.

[0082] Furthermore, organic peroxides of formulas (I) and (II) advantageously have a storage temperature below 0°C.

[0083] The organic peroxides of formulae (I) and (II) are advantageously liquid at storage temperature, preferably at a storage temperature below 0°C, measured at atmospheric pressure.

[0084] Preferably, the composition according to the invention comprises: one or more organic peroxides of formula (I):

[0085] Formula (I), in which R 1< and R 2< are identical and represent a C 1 -C 16 alkyl group, in particular C 3 -C 12 , even more preferably C 3 -C 10 , linear or branched, preferably branched; one or more organic peroxides of formula (II):

[0086] Formula (II) in which: R 3< represents a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular a C 7 -C 10 alkyl group, linear, branched or cyclic, preferably branched, which may comprise, preferably interrupted by, one or more oxygen atoms, preferably an oxygen atom; R 4< represents: i) a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular a C 7 -C 10 alkyl group, linear or branched, preferably branched, which may comprise, preferably interrupted by, one or more oxygen atoms, preferably an oxygen atom;ii) a linear or branched C 1 -C 7 alkyl group, preferably C 2 -C 6 , preferably branched, optionally substituted by one or more hydroxyl groups, or iii) a cyclic C 7 -C 10 alkyl group, in particular C 9 , cyclic, said organic peroxide of formula (II) being a hydroxyperoxyester or at least one of said organic peroxides of formula (II) being a hydroxyperoxyester.;

[0087] Advantageously, in accordance with this preferred embodiment, in formula (I), R 1< and R 2< are identical and represent a C 2 -C 8 alkyl group, linear or branched, preferably branched.

[0088] Advantageously, in accordance with this preferred embodiment, R 3< and R 4< are different.

[0089] Even more advantageously, in accordance with this preferred embodiment, in formula (II): R 3< represents a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular a C 7 -C 10 alkyl group, linear or branched, preferably linear; R 4< represents a C 1 -C 7 alkyl group, preferably a C 2 -C 6 alkyl group, linear or branched, preferably branched, optionally substituted by one or more hydroxyl groups.

[0090] Advantageously also, in accordance with this preferred embodiment, in formula (II), R 4< represents a C 1 -C 7 alkyl group, preferably C 2 -C 6 , linear or branched, preferably branched, optionally substituted by one or more hydroxyl groups.

[0091] Advantageously also, in accordance with this preferred embodiment, in formula (II), R 4< represents a C 1 -C 7 alkyl group, preferably C 2 -C 6 , linear or branched, preferably branched, substituted by one or more hydroxyl groups, in particular a hydroxyl group.

[0092] More advantageously, the composition according to the invention comprises di(2-ethylhexyl) peroxydicarbonate, in particular sold under the trade name Luperox ®< 223, or di-sec-butyl peroxydicarbonate, in particular sold under the trade name Luperox ®< 225 and hydroxyperoxyesters of formula (II), preferably 3-hydroxy-1,1 dimethylbutyl peroxyneodecanoate, in particular sold under the trade name Luperox ®< 610.

[0093] Preferably, the composition may comprise one or more antifreeze agents preferably chosen from the group consisting of monoalcohols, diols and triols.

[0094] Preferably, the antifreeze agent is selected from the group consisting of methanol, ethanol, ethylene glycol, isopropanol, n-propanol, propane-1,2-diol, propane-1,3-diol, glycerol, butan-1-ol, butan-2-ol, butan-1,3-diol and butan-1,4-diol and mixtures thereof, these mixtures comprising at least two of the antifreeze agents listed above, advantageously a mixture of ethanol and propane-1,2-diol.

[0095] Preferably, the antifreeze agent is selected from the group consisting of methanol, ethanol and propane-1,2-diol and mixtures thereof, in particular a mixture of ethanol and propane-1,2-diol. Most preferably, the antifreeze agent is propane-1,2-diol.

[0096] The antifreeze agent is preferably present in the composition according to the invention in a content of less than 40% by weight, preferably less than 25% by weight, preferably less than 22% by weight relative to the total weight of the composition. Such antifreeze contents allow the aqueous phase to remain in liquid form down to temperatures below -20°C, preferably down to temperatures below -25°C.

[0097] Preferably, the composition according to the invention contains less than 10% by weight of ethanol relative to the total weight of the composition.

[0098] Preferably, the composition according to the invention is free of ethanol.

[0099] Preferably, the composition according to the invention contains less than 10% by weight of methanol relative to the total weight of the composition.

[0100] Preferably, the composition according to the invention is free of methanol.

[0101] Preferably, the composition according to the invention comprises less than 10% by weight of ethanol or methanol relative to the total of the composition. If the composition according to the invention comprises both ethanol and methanol, their total content by weight is less than 10% relative to the total weight of the composition.

[0102] The composition according to the invention may also comprise one or more emulsifying agents.

[0103] Preferably, the emulsifying agent is a non-ionic surfactant.

[0104] Preferably, the emulsifying agent is a non-ionic surfactant, oxyalkylenated or not, chosen from the group consisting of fatty alcohols, fatty acids, sorbitans, vegetable or animal oils (hydrogenated or not); or mixtures thereof.

[0105] The oxyalkylenated units are more particularly oxyethylenated units (i.e. ethylene oxide groups), oxypropylenated units (i.e. propylene oxide groups), or their combination, preferably oxyethylenated or a combination of oxyethylenated units and oxypropylenated units.

[0106] In other words, the non-ionic surfactant is preferably chosen from the group consisting of fatty alcohols having oxyethylenated units and optionally oxypropylenated units, fatty acids having oxyethylenated units and optionally oxypropylenated and oxypropylenated units, vegetable or animal oils, optionally hydrogenated, having oxyethylenated units and optionally oxypropylenated units.

[0107] The oxyethylenated (i.e. ethylene oxide groups) and oxypropylenated (i.e. propylene oxide groups) units can be distributed statistically or in bulk.

[0108] The number of moles of ethylene and / or propylene oxide preferably varies from 1 to 250, more particularly from 2 to 100, better still from 2 to 50 and more particularly from 2 to 40.

[0109] Preferably, the number of moles of ethylene oxide ranges from 2 to 40.

[0110] For the purposes of the present invention, the term "fatty alcohol" means an alcohol comprising at least 8 carbon atoms, preferably a C 8 -C 40 alcohol, preferably a C 8 -C 20 alcohol.

[0111] Among the fatty alcohols, we can cite in particular 2-octyl dodecanol, decanol, lauryl alcohol, oleocetyl alcohol, isodecanol, oxo isotridecanol, cetostearyl alcohol, caprylic alcohol, myristyl alcohol, hexadecanoic or palmitic alcohol, stearic alcohol, eicosanoic or arachidic alcohol, behenyl alcohol, oleyl alcohol, eicosenoic or gadolic alcohol, docosenoic alcohol, ricinoleic alcohol, linoleic alcohol, linolenic alcohol.

[0112] Preferably, the non-ionic surfactant is chosen from the group consisting of oxyalkylenated fatty alcohols preferably chosen from octyl dodecanol, decanol, lauryl alcohol, oleocetyl alcohol, isodecanol, capric alcohol, oxo isotridecanol alcohol, cetostearyl alcohol, eleostearyl alcohol, caprylic alcohol, myristyl alcohol, hexadecanoic or palmitic alcohol, stearic alcohol, eicosanoic or arachidic alcohol, behenyl alcohol, oleyl alcohol, eicosenoic or gadolic alcohol, docosenoic alcohol, ricinoleyl alcohol, linoleyl alcohol, linolenic alcohol, oxyalkylenated, preferably oxyethylenated and / or oxypropylenated linolenic alcohol, and more preferably oxyethylenated and possibly oxypropylenated.

[0113] Preferably, the oxyalkylenated fatty alcohols are selected from the group consisting of oxyethylenated linoleic alcohol, oxyethylenated linolenic alcohol, oxyethylenated eleostearic alcohol and mixtures thereof.

[0114] The fatty alcohols mentioned above may possibly be oxypropylenated to a minor extent.

[0115] Preferably, the oxyalkylenated vegetable / animal oils (hydrogenated or not) are in particular derivatives of ethoxylated mono, di and triglycerides and comprise a complex mixture of ethoxylated glycerol linked or not to one or more fatty acid chains (themselves ethoxylated or not), of fatty acids ethoxylated on the acid function and / or on the hydroxyl function carried by the fatty acid chain, as well as variable proportions of fatty acids, glycerol and mono, di or triglycerides of fatty acids.

[0116] For the purposes of this document, the term "fatty acid" means an acid or a mixture of acids comprising at least 6 carbon atoms, preferably from 6 to 60 carbon atoms, better still from 6 to 20 carbon atoms.

[0117] The oxyalkylenated vegetable / animal oils (hydrogenated or not) are preferably chosen from the group consisting of vegetable oils, optionally hydrogenated, oxyethylenated (or ethoxylated).

[0118] The optionally hydrogenated, oxyethylenated vegetable oils are preferably chosen from the group consisting of ethoxylated castor oil and ethoxylated hydrogenated castor oil comprising from 20 to 40 moles of ethylene oxide per mole of ricinoleic acid. Mention may also be made of ethoxylated oils derived from copra, palm, palm kernel, olive, peanut, rapeseed, soybean, sunflower, walnut, hazelnut, coconut, poppy seed, safflor, linseed, perilla, oitica, and Chinese wood oils.

[0119] Ethoxylated fats based on tallow, crude or refined tall, whale, herring, and sardine oils may also be mentioned. All of these ethoxylated glyceride derivatives are characterized in that they comprise mixtures of ethoxylated mono, di, or triglycerides as well as ethoxylated derivatives of fatty acids and the corresponding glycerol. These fatty acids are in particular derived from the saturated or unsaturated fatty acids of caproic, caprylic, capric, lauric, myristic, palmitic, stearic, arachic, behenic, myristoleic, palmitoleic, oleic, ricinoleic, erucic, litioleic, linolenic, oleostearic, licanic, gadoleic, and erneic acids. Some unsaturated fatty acids are hydrogenated or not, as in the case of ethoxylated castor oil, where the ricinoleic group has been partially or fully hydrogenated or not.

[0120] Preferably, the non-ionic surfactant is chosen from the group consisting of oxyalkylenated vegetable or animal oils (hydrogenated or not).

[0121] Preferably, the non-ionic surfactant is chosen from the group consisting of vegetable oils, optionally hydrogenated, oxyethylenated and optionally oxypropylenated.

[0122] Preferably again, the non-ionic surfactant is chosen from the group consisting of ethoxylated vegetable oils, optionally hydrogenated, containing from 20 to 40 moles of ethylene oxide, in particular ethoxylated castor oil and ethoxylated hydrogenated castor oil containing from 20 to 40 moles of ethylene oxide.

[0123] Even more preferably, the non-ionic surfactant is ethoxylated castor oil containing 20 to 40 moles of ethylene oxide.

[0124] The emulsifying agent may be present in the composition according to the invention in a content ranging from 0.1 to 10% by weight, preferably in a content ranging from 0.5 to 5% by weight, relative to the total weight of the composition.

[0125] Preferably, the emulsifying agent according to the invention does not comprise partially hydrolyzed polyvinyl acetate, even more preferably does not comprise polyvinyl acetate, even more preferably does not comprise polyvinyl acetate or cellulose ester. This makes it possible in particular to reduce the preparation time at the industrial level, because the polyvinyl acetate which is in solid form requires a prior dissolution step, and to minimize the risks linked to the handling of powders.

[0126] The composition according to the invention may also comprise one or more additives intended to provide the final composition with particular properties / characteristics. These additives will ideally be present for the final polymerization or copolymerization.

[0127] The additive can be selected from the group consisting of anti-foaming agents, chain transfer agents, chain extenders, pH regulating agents, plasticizers and their mixtures.

[0128] Preferably, the composition according to the invention comprises one or more plasticizers, preferably chosen from the group consisting of phthalates, adipates, benzoates and hydrogenated derivatives of these molecules, including in particular diisononylcyclohexane and di-isononyl cyclohexane dicarboxylate and mixtures thereof. Preferably, the composition according to the invention comprises: one or more organic peroxides of formula (I):

[0129] Formula (I), in which R 1< and R 2< are identical and represent a C 1 -C 16 alkyl group, in particular C 3 -C 12 , even more preferably C 3 -C 10 , linear or branched, preferably branched; one or more organic peroxides of formula (II):

[0130] Formula (II) in which: R 3< represents a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular a C 7 -C 10 alkyl group, linear, branched or cyclic, preferably branched, which may comprise, preferably interrupted by, one or more oxygen atoms, preferably an oxygen atom; R 4< represents: i) a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular a C 7 -C 10 alkyl group, linear or branched, preferably branched, which may comprise, preferably interrupted by, one or more oxygen atoms, preferably an oxygen atom; ii) a C 1 -C 7 alkyl group, preferably a C 2 -C 6 alkyl group, linear or branched, preferably branched, optionally substituted by one or more hydroxyl groups;or iii) a cyclic C 7 -C 10 alkyl group, in particular C 9 , cyclic, said organic peroxide of formula (II) being a hydroxyperoxyester or at least one of said organic peroxides of formula (II) being a hydroxyperoxyester. one or more emulsifying agents, preferably chosen from the group consisting of alkoxylated fatty alcohols, alkoxylated fatty acids and alkoxylated vegetable or animal oils (hydrogenated or not) or mixtures thereof, preferably vegetable oils, optionally hydrogenated, alkoxylated, optionally one or more antifreeze agents, preferably chosen from the group consisting of ethanol, methanol and propane-1,2-diol. ;

[0131] Preferably, the composition according to the invention comprises: one or more organic peroxides of formula (I): Formula (I), in which R 1< and R 2< are identical and represent a C 1 -C 16 alkyl group, in particular C 3 -C 12 , even more preferably C 3 -C 10 , linear or branched, preferably branched; one or more organic peroxides of formula (II),

[0132] Formula (II) in which: R 3< represents a C 7 -C 20 alkyl group, preferably a C 7 -C 16 alkyl group, in particular a C 7 -C 10 alkyl group, linear or branched, preferably branched; R 4< represents a C 1 -C 7 alkyl group, preferably a C 2 -C 6 alkyl group, linear or branched, preferably branched, optionally substituted by one or more hydroxyl groups, said organic peroxide of formula (II) being a hydroxyperoxyester or at least one of said organic peroxides of formula (II) being a hydroxyperoxyester. one or more emulsifying agents chosen from the group consisting of non-ionic surfactants, preferably chosen from the group consisting of alkoxylated fatty alcohols, alkoxylated fatty acids and alkoxylated vegetable or animal oils (hydrogenated or not) or mixtures thereof, optionally one or more antifreeze agents preferably chosen from the group consisting of ethanol, methanol and propane-1,2-diol. Preparation of the composition

[0133] Preferably, the composition according to the invention can be prepared according to a process successively comprising: (i) the mixture: (a) of at least one organic peroxide of formula (I): Formula (I) in which R 1< and R 2< , identical or different, represent a linear, branched or cyclic C 1 -C 20 alkyl group, which may comprise one or more heteroatoms, preferably one or more oxygen atoms; and (b) at least one organic peroxide of formula (II):

[0134] Formula (II) in which R 3< and R 4<, identical or different, represent a linear, branched or cyclic C 1 -C 20 alkyl group, which may comprise one or more heteroatoms, preferably one or more oxygen atoms, and / or optionally substituted by one or more hydroxyl groups, said organic peroxide of formula (II) being a hydroxyperoxyester or at least one of said organic peroxides of formula (II) being a hydroxyperoxyester. (ii) Optionally, emulsifying the mixture.

[0135] Thus, the invention also relates to a process for preparing the composition according to the invention comprising successively (i) the mixture (a) of at least one organic peroxide of formula (I), as defined previously, and (b) of at least one organic peroxide of formula (II), as defined previously, (ii) the emulsification of the mixture.

[0136] In other words, the process for preparing the composition may successively comprise (i) at least one step of mixing (a) at least one organic peroxide of formula (I), as defined previously, and (b) at least one organic peroxide of formula (II), as defined previously, and (ii) optionally at least one step of emulsification of the mixture.

[0137] Preferably, the method according to the invention successively comprises: the addition of at least one emulsifying agent, as defined above, in water, the mixture of at least one organic peroxide of formula (I), as defined above, and at least one peroxide of formula (II), as defined above, in the aqueous phase, the emulsification of said mixture.

[0138] The composition according to the invention can be prepared by dispersing at least the emulsifying agent, and optionally one or more antifreeze agents as well as one or more additives, in water to obtain a homogeneous aqueous phase and then adding one or more organic peroxides of formula (I) and (II) to said aqueous phase, the whole then being emulsified during an emulsion step at a temperature below 5°C (Celsius), so as to limit premature degradation of the peroxide and preferably below -5°Celsius.

[0139] The above-mentioned steps can be performed in the particular order prescribed or in a different order.

[0140] The temperature at which the emulsion is prepared is not critical but it must be sufficiently low to avoid a significant rate of decomposition of the organic peroxide, which would result in a loss of strength. The temperature chosen depends on the organic peroxide. Furthermore, to prepare aqueous emulsions, deionized water or distilled water is conventionally used. The preparation process includes an emulsion step with a high shear mixer to optimally divide and / or homogenize the peroxide in the aqueous phase. Examples include mechanically rotating paddle and anchor stirrers, propeller stirrers, i.e., one or more stirrers mounted on a common shaft, and turbine stirrers, i.e., those with fixed baffles on the mixing tank or adjacent to the stirring members. Colloidal mills and homogenizers can also be used.

[0141] According to one embodiment feature, the method according to the invention is characterized in that an ultrasonic mixer or a rotor-stator mixer is used. Following the preparation of the emulsion, the steps of pumping and introducing the emulsions into a polymerization reactor must be carried out as quickly as possible. Thus, the peroxide emulsions must have a low viscosity. Thus, the organic peroxide emulsions according to the invention have a dynamic viscosity range at -10°C, 100 s -1< , less than 850 mPa.s, preferably less than 700 mPa.s, preferably less than 500 mPa.s just after production, (the viscosity measurements are measured for example according to the DIN 53019 standard, well known to those skilled in the art, with a device of the Viscotester Haake VT550 type, at -10°C and for a shear rate of 100 s -1< ).

[0142] Their flowability or flow time measured by a consistometric cutting technique is less than 200 seconds, preferably less than 100 seconds (DIN 53211, viscosity cup diameter 4 mm, temperature 5°C). The subsequent polymerization or copolymerization steps are, within the scope of the present invention, no different from those of the prior art. Use

[0143] The present invention also relates to the use of an aqueous emulsion composition comprising the mixture of organic peroxides, as defined above, for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, in particular of one or more vinyl monomers, preferably halogenated, and more preferably of vinyl chloride.

[0144] Examples of ethylenically unsaturated monomers include acrylates, vinyl esters, vinyl halide monomers, vinyl ethers, butadiene, and aromatic vinyl compounds such as styrene.

[0145] Preferably, the ethylenically unsaturated monomers are chosen from the group consisting of vinyl halide monomers (i.e. halogenated vinyl monomers), and more preferably vinyl chloride. Polymer

[0146] The disclosure describes a halogenated vinyl polymer obtained by polymerization of at least one ethylenically unsaturated monomer, as defined above, in the presence of the composition according to the invention as defined above.

[0147] The disclosure describes a poly(vinyl chloride) obtained by polymerization of vinyl chloride in the presence of the composition according to the invention, in particular of the mixture of organic peroxides, as defined above.

[0148] In particular, the polymerization of vinyl chloride monomer occurs in suspension at an initiation temperature ranging from 45°C to 70°C.

[0149] The following examples serve to illustrate the invention without, however, being limiting in nature. EXAMPLES Example 1

[0150] The following compositions A1, A2, A3 and B1 are prepared according to the procedure indicated below.

[0151] An emulsifying agent and an antifreeze agent are added to water.

[0152] The aqueous phase containing the emulsifying agent, namely the non-ionic surfactant, the antifreeze agent and water is stirred between 500 and 1000 revolutions per minute (rpm) and maintained at -5°C (Celsius) so as to obtain a homogeneous aqueous phase.

[0153] The organic peroxides are gradually added to the reactor containing this water / surfactant / antifreeze mixture. Stirring is maintained for three minutes at 2000 rpm. The mixture is then vigorously stirred using an "Ultraturrax type S-25N 18G" ultrasonic device for two minutes at 9500 rpm, then stirred using a paddle at 1000 rpm for one minute. Each emulsion is made on 200 grams in total. Tests carried out:

[0154] Dynamic viscosity measurements are carried out using a viscometer of the type "Viscotester Haake VT550". The measuring device is the "SV-DIN 53019", referring to the DIN 53019 standard. The measurement is carried out using coaxial cylinders which create the shear. Between 5 and 10 ml (milliliter) of emulsion is introduced into the measuring chamber maintained at -10°C. The values ​​given in the examples below correspond to a shear rate of 100 s -1< and are expressed in mPa.s. The measurement accuracy is ±10% of the indicated value.

[0155] Flow time measurements are carried out using consistometric cups according to DIN 53211 (viscosity cup diameter: 4 mm), well known to those skilled in the art. The measurement is carried out on 100 g of emulsion after conditioning at +5 °C. Flow time measurements are expressed in seconds and the accuracy is ±10% of the indicated value.

[0156] The average droplet size as well as the maximum droplet size are determined by conventional means using the light diffraction technique for a period ranging from 1 to 6 months at a temperature of -25°C / - 20°C.

[0157] Measurements are made using a Malvern Master Sizer 2000 ® device at room temperature. The average droplet size and the maximum droplet size are given with an accuracy of ± 0.5 µm (micrometer). Compositions:

[0158] The quantities of the ingredients below are indicated as a percentage by weight relative to the total weight of the composition in Table 1 below: [Table 1] A1 (comp) A2 (comp) A3 (comp) B1 (inv) Di-sec-butyl peroxydicarbonate (Luperox ®< 225) 50% 50% 50% 50% 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox ®< 610) - - - 3% Ethoxylated castor oil (310E) (Surfaline ®< R31L) 1,44% - - - Ethoxylated castor oil (20OE) (Surfaline ®< R20) - 1,50% 1,50% 1,50% Propane-1,2-diol 21,4% 21,4% 5,4% 21,4% Ethanol - - 10% Water Qsp 100 Qsp 100 Qsp 100 Qsp 100 Results : At the time of production of the compositions

[0159] The results of average droplet size, maximum droplet size and viscosity cut at the time of production of compositions A1, A2, A3 and B1 are grouped in Table 2 below: ] [Table 2 A1 (comp) A2 (comp) A3 (comp) B1 (inv) Average droplet size (µm) 2,1 2,03 2,02 1,4 Maximum droplet size (µm) 5 5,8 5 3,3 Viscosity cut at T = +5°C (dry) 22 24 16 27

[0160] The results show that the composition according to the invention (composition B) has an average droplet size (µm) as well as a maximum droplet size lower than the comparative compositions A1, A2 and A3 not comprising such a mixture of organic peroxides. Stability of the tested compositions

[0161] The mean and maximum droplet sizes of composition B determined at 6 months of the tested compositions and stored at -20°C in a freezer are 2.2 and 7.6 µm respectively. Example 2 :

[0162] Composition A4, corresponding to an aqueous emulsion of di(2-ethylhexyl) peroxydicarbonate (Luperox ®< 223), and composition A5 corresponding to an aqueous emulsion of 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox ®< 610), are prepared according to a procedure similar to that described in example 1.

[0163] Composition B2 was prepared by mixing 67% by weight of composition A4 and 33% by weight of composition A5 together.

[0164] Composition B3 was prepared by adding di(2-ethylhexyl) peroxydicarbonate and 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate in an aqueous phase at a weight ratio of 67 / 33 in accordance with the procedure described in Example 1.

[0165] Compositions A4, A5, B2 and B3 are described in Tables 3 to 5 below. Compositions:

[0166] The quantities of the ingredients below are indicated as a percentage by weight relative to the total weight of compositions A4 and A5 in Table 3 below: [Table 3] A4 (comp) A5 (comp) Di(2-ethylhexyl) peroxydicarbonate (Luperox ®< 223) 60% - 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox ®< 610) - 50% Polyvinyl alcohol (Alcotex 552 P) 1.2% 1.6% Propane-1,2-diol 3.2% 6.7% Methanol 11% 9.8% Water Qsp 100 Qsp 100

[0167] The quantities of the ingredients below are indicated as a percentage by weight relative to the total weight of composition B2 in Table 4 below: The quantities of the ingredients below are indicated as a percentage by weight relative to the total weight of composition B2 in Table 4 below: [Table 4] B2 (inv) Di(2-ethylhexyl) peroxydicarbonate (Luperox ®< 223) 40.1% 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox ®< 610) 18.4% Polyvinyl alcohol (Alcotex 552 P) 1.2% Propane-1,2-diol 3.2% Methanol 11.0% Water Qsp 100 Results : Stability of the tested compositions

[0168] The results of average droplet size and maximum droplet size determined at the time of manufacture of the tested compositions and over a period of time ranging from 1 to 6 months are grouped in Table 5 below: [Table 5] A4 (comp) A5 (comp) B2 (inv) T 0 Average droplet size (µm) 3.5 2.1 2.7 Maximum droplet size (µm) 10 7.6 8.7 T+1 month Average droplet size (µm) 3.9 3.8 3.3 Maximum droplet size (µm) 11.5 11.5 10 T+2 months Average droplet size (µm) 4.1 5.3 3.4 Maximum droplet size (µm) 13.2 20 10 T+3 months Average droplet size (µm) 4.2 6 3.5 Maximum droplet size (µm) 13.2 22.9 10 T+4 months Average droplet size (µm) 4.3 6.6 3.7 Maximum droplet size (µm) 13.2 22.9 10 T+6 months Average droplet size (µm) 4.5 7.1 4 Maximum droplet size (µm) 13.2 26.3 10

[0169] The results show that the compositions according to the invention (composition B2) have an average droplet size (µm) as well as a maximum droplet size lower than the comparative compositions A4 and A5 not comprising such a mixture of organic peroxides. Example 3 :

[0170] Composition A6, corresponding to an aqueous emulsion of di(2-ethylhexyl) peroxydicarbonate (Luperox ®< 223), and composition A7 corresponding to an aqueous emulsion of 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox ®< 610), are prepared according to a procedure similar to that described in example 1.

[0171] Composition B3 was prepared by mixing 73% by weight of composition A6 and 27% by weight of composition A7 together to obtain a weight ratio of 80 / 20.

[0172] Composition B4 was prepared by mixing 65% by weight of composition A6 and 35% by weight of composition A7 together to obtain a weight ratio of 80 / 20.

[0173] Composition B5 was prepared by mixing di(2-ethylhexyl) peroxydicarbonate and 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate added in an aqueous phase in a weight ratio of 80 / 20 and in accordance with the procedure described in Example 1.

[0174] Composition B6 was prepared by mixing di(2-ethylhexyl) peroxydicarbonate and 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate added in an aqueous phase in a weight ratio of 70 / 30 and in accordance with the procedure described in Example 1.

[0175] Compositions A6, A7, B3, B4, B5 and B6 are described in Tables 6 to 8 below. Compositions:

[0176] The quantities of the ingredients below are indicated as a percentage by weight relative to the total weight of compositions A6 and A7 in Table 6 below: Table 6] A6 (comp) A7 (comp) Di(2-ethylhexyl) peroxydicarbonate (Luperox ®< 223) 60% - 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox ®< 610) - 50% Surfaline R20 Ethoxylated Castor Oil 1.2% 1.2% Ethanol 9% 9% Propane-1,2-diol 6% 7.5% Water Qsp 100 Qsp 100

[0177] The quantities of the ingredients below are indicated as a percentage by weight relative to the total weight of composition B3 in Table 7 below: [Table 7] B3 (inv) Di(2-ethylhexyl) peroxydicarbonate (Luperox ®< 223) 44% 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox ®< 610) 11% Surfaline R20 Ethoxylated Castor Oil 1.2% Ethanol 9% Propane-1,2-diol 7.5% Water Qsp 100

[0178] The quantities of the ingredients below are indicated as a percentage by weight relative to the total weight of composition B4 in Table 8 below: [Table 8] B4 (inv) Di(2-ethylhexyl) peroxydicarbonate (Luperox ®< 223) 39% 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox ®< 610) 17% Surfaline R20 Ethoxylated Castor Oil 1.2% Ethanol 9% Propane-1,2-diol 7.5% Water Qsp 100

[0179] The quantities of the ingredients below are indicated as a percentage by weight relative to the total weight of composition B5 in Table 9 below: [Table 9] B5 (inv) Di(2-ethylhexyl) peroxydicarbonate (Luperox ®< 223) 46% 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox ®< 610) 12% Surfaline R20 Ethoxylated Castor Oil 1.2% Ethanol 9% Propane-1,2-diol 7.5% Water Qsp 100

[0180] The quantities of the ingredients below are indicated as a percentage by weight relative to the total weight of composition B6 in Table 10 below: [Table 10] B6 (inv) Di(2-ethylhexyl) peroxydicarbonate (Luperox ®< 223) 40% 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate (Luperox ®< 610) 17% Surfaline R20 Ethoxylated Castor Oil 1.2% Ethanol 9% Propane-1,2-diol 7.5% Water Qsp 100 Results : Stability of the tested compositions

[0181] The results of average droplet size and maximum droplet size determined at the time of manufacture of the tested compositions and over a period of time ranging from 1 to 6 months are grouped in Table 11 below. [Table 11] A6 (comp) A7 (comp) B3 (inv) B4 (inv) B5 (inv) B6 (inv) T+1 month Average droplet size (µm) 2.2 7.3 1.7 1.7 1 12 Maximum droplet size (µm) 6.6 30.2 4.4 5 2.9 3.8 T+6 months Average droplet size (µm) 2.6 12.8 1.8 2 1.5 1.8 Maximum droplet size (µm) 7.6 120.2 5 5.8 5 5

[0182] The results show that the compositions according to the invention (compositions B3 to B6) have an average droplet size (µm) as well as a maximum droplet size lower than the comparative compositions A6 and A7 which do not comprise such a mixture of organic peroxides.

Claims

1. Aqueous emulsion composition comprising: - one or more organic peroxides of formula (I): in which formula (I) R1 and R2, which may be identical or different, represent a linear, branched or cyclic C1-C20 alkyl group which may comprise, and is preferably interrupted with, one or more heteroatoms, preferably one or more oxygen atoms; - one or more organic peroxides of formula (II): in which formula (II) R3 and R4, which may be identical or different, represent a linear, branched or cyclic C1-C20 alkyl group which may comprise, and is preferably interrupted with, one or more heteroatoms, preferably one or more oxygen atoms, and / or is optionally substituted with one or more hydroxyl groups, said organic peroxide of formula (II) being a hydroxyperoxyester or at least one of said organic peroxides of formula (II) being a hydroxyperoxyester; the organic peroxide(s) of formula (I) and the organic peroxide(s) of formula (II) being present in a concentration ranging from 40% to 70% by weight relative to the total weight of the composition, preferably ranging from 40% to 65% by weight relative to the total weight of the composition, more preferentially ranging from 40% to 60% by weight relative to the total weight of the composition.

2. Composition according to Claim 1, characterized in that R1 and R2, which may be identical or different, represent a linear or branched C1-C16, more preferentially C3-C12, in particular C3-C10, alkyl group which may comprise one or more heteroatoms, preferably one or more oxygen atoms.

3. Composition according to Claim 1 or 2, characterized in that R1 and R2 are identical and represent a linear or branched, preferably branched, C1-C16, more preferentially C3-C12, in particular C3-C10, alkyl group.

4. Composition according to any one of Claims 1 to 3, characterized in that the peroxides of formula (I) are chosen from the group consisting of bis(2-ethylhexyl) peroxydicarbonate, di(sec-butyl) peroxydicarbonate, bis(1-methylheptyl) peroxydicarbonate, di(n-propyl) peroxydicarbonate, bis(3-methoxybutyl) peroxydicarbonate, diethyl peroxycarbonate and mixtures thereof, preferably bis(2-ethylhexyl) peroxydicarbonate and di(sec-butyl) peroxydicarbonate.

5. Composition according to any one of the preceding claims, <b>characterized in that: - R3 represents a linear, branched or cyclic, preferably branched, C7-C20 alkyl group, preferably a C7-C16 alkyl group, in particular a C7-C10 alkyl group, which may comprise, and is preferably interrupted with, one or more oxygen atoms, preferably one oxygen atom; - R4 represents: i) a linear or branched, preferably branched, C7-C20, preferably C7-C16, in particular C7-C10, alkyl group which may comprise, and is preferably interrupted with, one or more oxygen atoms, preferably one oxygen atom; ii) a linear or branched, preferably branched, C1-C7, preferably C2-C7, alkyl group optionally substituted with one or more hydroxyl groups, iii) a cyclic C7-C10, in particular cyclic C9, alkyl group.

6. Composition according to any one of the preceding claims, characterized in that the peroxides of formula (II) are hydroxyperoxyesters 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 peroxyneo-decanoate, 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 mixtures thereof, preferably 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate.

7. Composition according to any one of the preceding claims, characterized in that the weight ratio of organic peroxide(s) of formula (I) / peroxide(s) of formula (II) ranges from 99 / 1, in particular from 97 / 3, in particular from 90 / 10 and preferentially from 80 / 20 to 50 / 50.

8. Composition according to any one of the preceding claims, characterized in that it also comprises one or more antifreezes.

9. Composition according to any one of the preceding claims, characterized in that it comprises ethanol or methanol in a content of less than 10% by weight.

10. Composition according to any one of the preceding claims, characterized in that it comprises one or more emulsifiers.

11. Composition according to any one of the preceding claims, characterized in that it comprises an average organic peroxide droplet size of less than 10 µm, preferably less than 5 µm and a maximum droplet size of less than 20 µm, preferably less than 15 µm.

12. Process for preparing a composition as defined according to any one of Claims 1 to 12, characterized in that it successively involves: (i) mixing: (a) at least one organic peroxide of formula (I) as defined according to any one of Claims 1 to 4, (b) at least one organic peroxide of formula (II) as defined according to any one of Claims 1 and 5 to 7, (ii) optionally emulsifying the mixture.

13. Use of the composition as defined according to any one of Claims 1 to 11, for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, preferably one or more halogenated vinyl monomers, and more preferentially vinyl chloride.