Aqueous organic peroxide emulsion

Abstract

To provide an aqueous emulsion of an organic peroxide that can be used for polymerization or copolymerization of ethylenically unsaturated monomers, in particular vinyl chloride.SOLUTION: Provided is an aqueous emulsion of an organic peroxide comprising at least one peroxyester, at least one antifreeze, and a combination of at least two emulsifying agents selected from the group consisting of a non-ethoxylated sorbitan ester, an ethoxylated sorbitan ester and an ethoxylated fatty alcohol.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to aqueous emulsions of peroxyesters that can be used in the polymerization or copolymerization of ethylenically unsaturated monomers, especially vinyl chloride.

[0002] The precautions inherent in the instability of organic peroxides are an essential part of the knowledge known to those skilled in the art. Furthermore, due to their unstable nature, organic peroxides are used inter alia as initiators for the polymerization of vinyl monomers.

[0003] The most reactive organic peroxides are usually conditioned in the form of an aqueous emulsion in the presence of antifreeze. This conditioning allows both to absorb and dissipate the energy generated during possible peroxide decomposition events and to maintain the emulsion in a liquid state at temperatures below -10°C, typically below -20°C. This conditioning therefore limits unintended decomposition of the peroxide.

[0004] Organic peroxide emulsions generally contain, in addition to water and antifreeze, an emulsifier to reduce the surface tension between the aqueous phase and the organic peroxide, promote its dispersion in droplet form, and stabilize these droplets (maintain droplet size) over time.

[0005] The stability of organic peroxide emulsions is essential not only from the standpoint of safety (during production, transport and storage) but also for use during polymerization.

[0006] This is because the use of heterogeneous organic peroxide emulsions as polymerization initiators in vinyl monomer emulsions or suspensions can result in heterogeneity in the final product. The heterogeneity is typically characterized by polymer particles ("fish eyes," hard particles) that barely gel during application in the dissolved form. The presence of hard particles, however, makes the polymer material opaque. Therefore, these stability considerations are very important in applications where transparency of the final product is crucial, especially in medical applications.

[0007] Therefore, it is essential to maintain good stability of the organic peroxide emulsion until the time of its use.

[0008] However, emulsions become unstable over time, causing the average size of the peroxide droplets to increase. This increase in droplet size can lead to phase separation. Peroxide emulsions are generally considered satisfactory if the average droplet size does not exceed 5 μm, the maximum droplet size does not exceed 20 μm, and the droplet size distribution is uniform.

[0009] Furthermore, the steps of removing the organic peroxide emulsion from the intermediate storage silo, pumping it, and introducing it into the polymerization reactor are critical to the quality of the resulting polymer and the reliability of the polymerization process. These steps must be carried out as quickly as possible. To achieve this, it is very important that the organic peroxide emulsion has a low viscosity so that the flow of the emulsion is as facilitated as possible. Therefore, the organic peroxide emulsion is heated at -10°C and a shear rate of 100 s -1 (dynamic viscosity measurements are carried out, for example, according to standard DIN 53019, using concentric cylinders which generate shear).

[0010] However, those skilled in the art know that in this type of emulsion, any attempt to reduce the droplet size contributes to an increase in viscosity (see the article by JP Canselier and M. Poux, "Procedes d'emulsification-Mecanisme de formation des emulsions [Emulsification processes-emulsion formation mechanism]", Techniques de l'Ingenieur J2 152, pp. 1-12, published June 10, 2004, paragraph 1.4).

[0011] Therefore, achieving these two main goals simultaneously presents a considerable challenge to those skilled in the art due to the conflicting choices that they will have to make. [Background technology]

[0012] WO99 / 05101 discloses the use of partially hydrolyzed polyvinyl acetate (PVA) as a colloidal agent in combination with a nonionic surfactant having an HLB (hydrophilic-lipophilic balance) value greater than 16 in an aqueous emulsion of peroxyester. A low viscosity is required for the peroxide emulsion. Therefore, the document states that a surfactant having an HLB value less than 16 may increase the final viscosity of the emulsion.

[0013] Similarly, WO 03 / 095500 discloses the use of partially hydrolyzed PVA in combination with a nonionic surfactant having an HLB value greater than 15 in aqueous emulsions of peroxydicarbonates or diacyl peroxides, and also states that the addition of surfactants with an HLB value less than 10 has a detrimental effect, increasing the final viscosity of the organic peroxide emulsion. Summary of the Invention

[0014] Applicants have discovered that the use of a combination of two particular emulsifiers surprisingly stabilizes aqueous emulsions of organic peroxides while at the same time providing a viscosity that allows for good utilization of the emulsion.

[0015] Therefore, the present invention provides at least one peroxyester, - at least one antifreeze, - the below described: - non-ethoxylated sorbitan esters, ethoxylated sorbitan esters, - ethoxylated fatty alcohols A combination of at least two emulsifiers selected from the group consisting of The present invention relates to an aqueous emulsion of a peroxyester, comprising:

[0016] Therefore, the present invention aims to prevent the average droplet size (d 50 The emulsions according to the invention have a very low viscosity which allows for very short flow times, making them compatible with the polymerization of ethylenically unsaturated derivatives, in particular vinyl monomers such as vinyl chloride monomer.

[0017] The present invention provides a method for preparing an aqueous emulsion of a peroxyester, comprising the steps of: - at least one antifreeze, - a combination of at least two emulsifiers selected from the group consisting of 1) non-ethoxylated sorbitan esters, 2) ethoxylated sorbitan esters, and 3) ethoxylated fatty alcohols; - water, - at least one peroxyester The present invention also relates to a method comprising the step a) of mixing

[0018] The present invention also relates to the use of an emulsion as defined above for the polymerization of ethylenically unsaturated monomers.

[0019] Other characteristics and advantages of the present invention will appear more clearly from a reading of the specification and the examples that follow.

[0020] In the following text, unless otherwise indicated, the limits of the ranges of values ​​are included in this document.

[0021] The phrase "at least one" is equivalent to the phrase "one or more." DETAILED DESCRIPTION OF THE INVENTION

[0022] emulsion Preferably, said at least one peroxyester is present in a content of between 30% and 70% by weight, preferably between 35% and 65% by weight and more preferentially between 40% and 60% by weight, relative to the total weight of the composition.

[0023] Preferably, the peroxyester is peroxyneodecanoates, such as α-cumyl peroxyneodecanoate, 2,4,4-trimethylpentyl 2-peroxyneodecanoate, 3-hydroxy-1,1-tert-butyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, dimethylbutyl peroxyneodecanoate and 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, peroxyneoheptanoates, such as 3-hydroxy-1,1-dimethylbutylperoxyneoheptanoate, α-cumylperoxyneoheptanoate and tert-butylperoxyneoheptanoate, peroxypivalates, such as tert-amyl peroxypivalate and tert-butyl peroxypivalate; peroxyethylhexanoates, such as tert-amyl 2-peroxyethylhexanoate, tert-butyl 2-peroxyethylhexanoate, 1,1,3,3-tetramethylbutyl 2-peroxyethylhexanoate, 3-hydroxy-1,1-dimethylbutyl 2-peroxyethylhexanoate, tert-butyl peroxyisobutyrate, and mixtures thereof is selected from the group consisting of:

[0024] Particularly preferably, the peroxyester is a peroxypivalate, in particular tert-butyl peroxypivalate or tert-amyl peroxypivalate, more preferentially tert-butyl peroxypivalate.

[0025] The tert-butyl peroxypivalate may be, for example, Luperox® 11 from Arkema.

[0026] The tert-amyl peroxypivalate may be, for example, Luperox® 554 from Arkema.

[0027] Alternatively, and particularly preferably, the peroxyester is a peroxyneodecanoate, in particular selected from the group consisting of tert-butyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, α-cumyl peroxyneodecanoate and 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, and more preferentially 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate.

[0028] Particularly preferably, the peroxyester is selected from the group consisting of tert-butyl peroxypivalate, tert-amyl peroxypivalate, tert-butyl peroxyneodecanoate, 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, tert-amyl peroxyneodecanoate and α-cumyl peroxydecanoate.

[0029] 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate may be, for example, Luperox® 610 from Arkema.

[0030] The alpha-cumyl peroxydecanoate may be, for example, Luperox® 188 from Arkema.

[0031] The tert-amyl peroxy neodecanoate may be, for example, Luperox® 546 from Arkema.

[0032] The tert-butyl peroxyneodecanoate may be, for example, Luperox® 10 from Arkema.

[0033] Preferably, the peroxyester is a liquid at room temperature.

[0034] To allow storage at temperatures below -10°C, preferentially below -20°C, the composition according to the invention comprises at least one antifreeze.

[0035] Preferably, the at least one antifreeze liquid is an alcohol, preferably selected from the group consisting of ethanol, ethylene glycol, isopropanol, n-propanol, 1,2-propanediol, 1,2-propanediol, 1,3-propanediol, glycerol, 1-butanol, 2-butanol, 1,3-butanediol, and 1,4-butanediol, and mixtures thereof, preferably selected from the group consisting of isopropanol, ethanol, propanediol, and mixtures thereof. Particularly preferably, the at least one antifreeze liquid is ethanol, optionally in combination with another alcohol, preferably selected from the group consisting of ethylene glycol, isopropanol, n-propanol, 1,2-propanediol, 1,2-propanediol, 1,3-propanediol, glycerol, 1-butanol, 2-butanol, 1,3-butanediol, 1,4-butanediol, and mixtures thereof.

[0036] Advantageously, said at least one antifreeze liquid comprises, and in particular consists of, a mixture of ethanol and propanediol, preferably 1,2-propanediol.

[0037] Preferably, the aqueous emulsion according to the invention comprises between 5 and 25% by weight of antifreeze, preferably between 10 and 20% by weight, relative to the total weight of the aqueous emulsion.

[0038] Preferably, the aqueous emulsion according to the invention comprises between 0 and 10% by weight of methanol, preferably between 0 and 5% by weight, preferably between 0 and 4% by weight, preferably between 0 and 3% by weight, preferably between 0 and 2% by weight, more preferentially between 0 and 1% by weight of methanol relative to the total weight of the emulsion, and particularly preferably no methanol.

[0039] For purposes of this invention, the term "emulsifier" means a compound that affects the surface tension at the interface between an aqueous phase and an organic phase that contains an organic peroxide.

[0040] For the purposes of the present invention, the expression "a combination of at least two emulsifiers selected from the group consisting of non-ethoxylated sorbitan esters, ethoxylated sorbitan esters and ethoxylated fatty alcohols" means that the combination at least one non-ethoxylated sorbitan ester and one ethoxylated sorbitan ester, at least one non-ethoxylated sorbitan ester and one ethoxylated fatty alcohol, or at least one ethoxylated sorbitan ester and one ethoxylated fatty alcohol This means that the

[0041] Preferably, the combination is at least one non-ethoxylated sorbitan ester and one ethoxylated sorbitan ester, or - at least one non-ethoxylated sorbitan ester and one ethoxylated fatty alcohol Includes.

[0042] In one particular embodiment, the combination may include at least one non-ethoxylated sorbitan ester, one ethoxylated sorbitan ester, and one ethoxylated fatty alcohol.

[0043] Preferably, the combination of at least two emulsifiers has an HLB of less than 13, preferably 12 or less, preferably 11 or less, more preferably 10 or less.

[0044] Preferably, the combination of at least two emulsifiers has an HLB of greater than 5, preferably 6 or greater, more preferably 7 or greater.

[0045] Preferably, the combination of at least two emulsifiers has an HLB between 5 and 13, preferably between 6 and 12, and more preferentially between 7 and 11.

[0046] The term "HLB" or "HLB value" refers to the hydrophilic-lipophilic balance that allows the evaluation of the solubility of an emulsifier in water. Preferably, the HLB is determined according to the method proposed by Griffin (Journal of the Society of Cosmetic Chemists, 5(4), (1954), 249-256).

[0047] The HLB of the combination of the at least two emulsifiers can be calculated from the mass ratio of the emulsifiers.

[0048] Preferably, the emulsifier according to the invention does not contain partially hydrolyzed polyvinyl acetate, more preferentially does not contain polyvinyl acetate, and even more preferentially does not contain polyvinyl acetate or cellulose ester, which makes it possible, inter alia, to reduce the industrial preparation time and to minimize the risks associated with handling the powder, since solid polyvinyl acetate requires a prior dissolution step.

[0049] Preferably, the ethoxylated fatty alcohol is a C4-C 30 , preferably C4 to C 20 , more preferably C 16 ~C 18 linear or branched, cyclic or acyclic, saturated or unsaturated, aromatic or non-aromatic fatty alcohols.

[0050] Preferably, the ethoxylated fatty alcohol is ethoxylated octyldodecanol, ethoxylated decanol, ethoxylated lauryl alcohol, ethoxylated oleocetyl alcohol, ethoxylated isodecanol, ethoxylated capryl alcohol, ethoxylated isotridecanol, ethoxylated cetostearyl alcohol, ethoxylated caprylyl alcohol, ethoxylated myristyl alcohol, ethoxylated hexadecanoyl or palmityl alcohol. alcohol, ethoxylated stearyl alcohol, ethoxylated eicosanoyl or arachidyl alcohol, ethoxylated behenyl alcohol, ethoxylated oleyl alcohol, ethoxylated eicosenoyl or gadolinyl alcohol, ethoxylated docosenoyl alcohol, ethoxylated ricinoleyl alcohol, ethoxylated linoleyl alcohol and ethoxylated linolenyl alcohol, and mixtures thereof.

[0051] Preferably, the fatty alcohol contains between 3 and 80 ethylene oxide groups, preferably between 20 and 40, preferentially between 22 and 30, more preferentially 25 ethylene oxide groups.

[0052] Particularly preferably, the fatty alcohol is a C4-C 30 , preferably C4 to C 20 , preferably C 16 ~C 18 , linear or branched, cyclic or acyclic, saturated or unsaturated, aromatic or non-aromatic fatty alcohols containing between 3 and 80 alkylene oxide units, preferably between 20 and 40, preferentially between 22 and 30, more preferentially 25 alkylene oxide groups. Advantageously, the fatty alcohol is a C 2 fatty alcohol containing 23 to 25 ethylene oxide groups. 16 ~C 18 The fatty alcohol is advantageously a C 2 alcohol containing 23 ethylene oxide groups, such as Surfaline® OC23L from Arkema. 18The fatty alcohol may advantageously be a C 2 alcohol containing 25 ethylene oxide groups, such as Surfaline® CS25L from Arkema. 18 It may also be alcohol.

[0053] Preferably, the non-ethoxylated sorbitan ester is selected from the group consisting of sorbitan monostearate, sorbitan tristearate, sorbitan monolaurate, sorbitan trilaurate, sorbitan monooleate, sorbitan trioleate, sorbitan monopalmitate, and sorbitan tripalmitate, and combinations thereof.

[0054] Sorbitan monooleate is available under the trade name Span80® (Croda).

[0055] Preferably, the ethoxylated sorbitan ester contains between 3 and 40 ethylene oxide groups, preferably between 5 and 20 ethylene oxide groups.

[0056] Preferably, the ethoxylated sorbitan ester is selected from the group consisting of ethoxylated sorbitan monostearate, ethoxylated sorbitan tristearate, ethoxylated sorbitan monolaurate, ethoxylated sorbitan trilaurate, ethoxylated sorbitan monooleate, ethoxylated sorbitan trioleate, ethoxylated sorbitan monopalmitate, ethoxylated sorbitan tripalmitate, and combinations thereof.

[0057] Sorbitan monooleate 20OE is available under the tradename Surfaline SE80® (Arkema) or Tween 80® (Croda).

[0058] Preferably, the combination of at least two emulsifiers comprises a non-ethoxylated sorbitan as defined above, and an ethoxylated sorbitan containing between 5 and 20 ethylene oxide groups.

[0059] Preferably, the combination of at least two emulsifiers is a combination of non-ethoxylated sorbitan as defined above and a C sorbitan containing between 22 and 30 ethylene oxide groups. 16 ~C 22 Contains ethoxylated alcohols.

[0060] Preferably, the at least two emulsifiers are present in a content ranging from 0.05% to 5% by weight of the emulsion, preferably from 1% to 2% by weight. The expression "the two emulsifiers are present in a content ranging from 0.05% to 5% by weight of the emulsion, preferably from 1% to 2% by weight" means that the total content of the two agents is in the range of 0.05% to 5% by weight of the emulsion, preferably from 1% to 2% by weight of the emulsion.

[0061] The emulsions according to the present invention may also contain one or more additives that may be specifically designed to provide particular properties / characteristics of the final thermoplastic composition.

[0062] Preferably, the additives are selected from the group consisting of antioxidants; UV protectants; processing agents which, when used, function to improve the final appearance, such as fatty amides, stearic acid and its salts, ethylene bis(stearamide) or fluoropolymers; anti-fog agents; anti-blocking agents, such as silica or talc; fillers, such as calcium carbonate, and nano-fillers, e.g. clays; coupling agents, such as silanes; anti-static agents; nucleating agents; pigments; dyes; plasticizers; flow agents and flame retardant additives, such as aluminum hydroxide or magnesium hydroxide; pH adjusters, such as phosphate and citrate buffers; chelating agents; biocides, e.g. fungicides; antiozonants, antioxidants; anti-degradants, swelling agents and release agents.

[0063] Preferably, the additive has no effect on the homogeneity of the solution.

[0064] Said additives may be added in amounts commonly used and known to those skilled in the art, these additives being generally used in a content of between 10 and 10,000 ppm by weight relative to the weight of the emulsion.

[0065] Preferably, emulsions according to the invention comprise water making up the remainder of the composition (up to 100%), preferably deionized or distilled water.

[0066] The aqueous emulsions according to the invention preferably have a viscosity at -10°C and 100°C of less than 1000 mPa·s, preferentially less than 700 mPa·s, more preferentially less than 500 mPa·s. -1 (Viscosity measurements are carried out, for example, according to standard DIN 53019, well known to those skilled in the art, using an instrument such as a Viscotester Haake VT550 at -10°C and a shear rate of 100 s -1 (measured in

[0067] The aqueous emulsions according to the invention preferably have a flow time of less than 200 seconds, preferentially less than 100 seconds (flow time measurements may be carried out, for example, using the Consistometer cup technique DIN 53211, viscosity cup diameter 4 mm, temperature 5°C).

[0068] method The present invention provides a method for preparing an aqueous emulsion of a peroxyester, comprising the steps of: - at least one antifreeze as defined above, a combination of at least two emulsifiers selected from the group consisting of 1) non-ethoxylated sorbitan esters, 2) ethoxylated sorbitan esters, and 3) ethoxylated fatty alcohols, as defined above; - water, - at least one peroxyester as defined above The present invention also relates to a method comprising the step a) of mixing

[0069] Preferably, step a) is carried out by mixing said at least one organic peroxide with an aqueous solution comprising said at least one antifreeze and said at least two emulsifiers.

[0070] Preferably, step a) is an emulsification step. Preferably, step a) is carried out at a temperature below 5° C., preferably below 0° C., and even more preferentially below −5° C. The use of such temperatures makes it possible to limit premature degradation of the organic peroxide.

[0071] Preferably, the aqueous emulsion is prepared using deionized or distilled water.

[0072] Preferably, the mixing step is carried out using a high-shear mixer in order to divide and / or homogenize the peroxide in the aqueous phase as much as possible. Examples of mixers that may be mentioned include mechanical rotating paddle and anchor type agitators, impeller type agitators, turbo mixers, ultrasonic mixers and rotor-stator type mixers.

[0073] Use of emulsions The present invention also relates to the use of an emulsion as defined above for the polymerization of ethylenically unsaturated monomers.

[0074] For purposes of this invention, the term "polymerization" means the polymerization of ethylenically unsaturated monomers alone or copolymerization thereof with comonomers.

[0075] Preferably, the polymerization is carried out at an initiation temperature between 45°C and 70°C.

[0076] Ethylenically unsaturated monomers that may be mentioned include butadiene, acrylates, vinyl esters, vinyl halides such as vinyl chloride, vinyl ethers, and aromatic vinyl compounds such as styrene, and vinylidene halides such as vinylidene chloride and vinylidene fluoride. Preferably, the ethylenically unsaturated monomer is vinyl chloride.

[0077] Polymerization method The present invention also relates to a process for polymerizing ethylenically unsaturated monomers, comprising polymerizing in the presence of an emulsion as defined above.

[0078] The following examples serve to illustrate the invention without limiting it. [Example]

[0079] Preparation of test composition formulations: The emulsion was prepared according to the following protocol: The aqueous phase containing the emulsifier, antifreeze, and water is stirred at between 500 and 1000 rpm (revolutions per minute) and maintained at -5°C (Celsius). The organic peroxide is gradually added to the reactor containing the water / emulsifier / antifreeze mixture. Stirring is maintained at 2000 rpm for 3 minutes. The whole is then vigorously stirred for 2 minutes at 9500 rpm using equipment such as an Ultra-Turrax S-25N 18G mixer, and then stirred for 1 minute at 1000 rpm using a paddle. Each emulsification is performed with a total of 200g.

[0080] The following emulsions were produced: - an antifreeze system consisting of an alcohol mixture of ethanol / 1,2-propanediol in a mass ratio of 60 / 40, with a total concentration of 16%; 40% of one of the following organic peroxides: Luperox® 11 (tert-butyl peroxypivalate), Luperox® 610 (3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate), Luperox® 10 (tert-butyl peroxyneodecanoate) and Luperox® 554 (tert-amyl peroxypivalate) from Arkema, - an emulsifier or a combination of emulsifiers, The remainder is distilled water. TIFF2025172790000001.tif220170

[0081] Tests performed: After 6 months of storage at -20°C, the following measurements were made: Dynamic viscosity measurements are carried out using a viscometer such as the Viscotester Haake VT550 instrument. The measuring device is SV-DIN53019, referring to the standard DIN53019. Measurements are carried out using concentric cylinders that generate shear. 5-10 ml (milliliters) of emulsion are introduced into the measuring chamber, which is maintained at -10°C. The values ​​given in the following examples are for a shear rate of 100 s -1 and is expressed in mPa·s.

[0082] The flow time measurements are carried out using a Consistometer cup according to the standard DIN 53211 (viscosity cup diameter: 4 mm), well known to those skilled in the art. After conditioning at +5° C., the measurement is carried out on 100 g of emulsion. The flow time measurements are expressed in seconds.

[0083] The droplet size is determined by conventional means using light scattering techniques. Measurements are carried out at room temperature using a Malvern Mastersizer 2000® instrument. The droplet size d is measured with an accuracy of ±0.5 μm (micrometers). 50 or d 100 Determine.

[0084] A sample taken from the top of the sample and another sample taken from the bottom of the emulsion sample are measured for organic peroxide concentration by HPLC. The emulsion is considered stable when the observed difference between the concentrations in the top and bottom samples is less than 4%.

[0085] The results are shown in Table 2 below. TIFF2025172790000002.tif201170

Claims

1. at least one peroxyester; at least one antifreeze; the below described: non-ethoxylated sorbitan esters, ethoxylated sorbitan esters, Ethoxylated Fatty Alcohols a combination of at least two emulsifiers selected from the group consisting of:

1. An aqueous emulsion of organic peroxide comprising:

2. 2. The emulsion of claim 1, wherein the combination of at least two emulsifiers has an HLB of less than 13, preferably 12 or less, preferably 11 or less, more preferably 10 or less.

3. 2. The emulsion of claim 1, wherein the non-ethoxylated sorbitan ester is selected from the group consisting of sorbitan monostearate, sorbitan tristearate, sorbitan monolaurate, sorbitan trilaurate, sorbitan monooleate, sorbitan trioleate, sorbitan monopalmitate, sorbitan tripalmitate, and combinations thereof.

4. 4. The emulsion of claim 1, wherein the ethoxylated sorbitan ester is selected from the group consisting of ethoxylated sorbitan monostearate, ethoxylated sorbitan tristearate, ethoxylated sorbitan monolaurate, ethoxylated sorbitan trilaurate, ethoxylated sorbitan monooleate, ethoxylated sorbitan trioleate, ethoxylated sorbitan monopalmitate, ethoxylated sorbitan tripalmitate, and combinations thereof.

5. The ethoxylated fatty alcohol is ４ ~C ３０ , preferably C ４ ~C ２０ , preferably C １６ ~C １８ 5. An emulsion according to claim 1 , characterized in that the alcohol is a linear or branched, cyclic or acyclic, saturated or unsaturated, aromatic or non-aromatic fatty alcohol of the formula (I), containing between 3 and 80 alkylene oxide units, preferably between 20 and 40, preferentially between 22 and 30, more preferentially 25 alkylene oxide groups.

6. 6. Emulsion according to any one of claims 1 to 5, characterized in that the at least two emulsifiers are present in a content ranging from 0.05% to 5% by weight of the emulsion, preferably from 1% to 2% by weight.

7. 7. Emulsion according to any one of claims 1 to 6, characterized in that the at least one organic peroxide is present in a content of between 30% and 70% by weight, preferably from 35% to 65% by weight and more preferentially from 40% to 60% by weight relative to the total weight of the composition.

8. the at least one peroxyester being Peroxyneodecanoates, such as α-cumyl peroxyneodecanoate, 2,4,4-trimethylpentyl 2-peroxyneodecanoate, 3-hydroxy-1,1-tert-butyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, tert-amyl peroxyneodecanoate, dimethylbutyl peroxyneodecanoate and 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate; Peroxyneoheptanoates, such as 3-hydroxy-1,1-dimethylbutylperoxyneoheptanoate, α-cumylperoxyneoheptanoate and tert-butylperoxyneoheptanoate; Peroxypivalates, such as tert-amyl peroxypivalate and tert-butyl peroxypivalate; Peroxyethylhexanoates, such as tert-amyl 2-peroxyethylhexanoate, tert-butyl 2-peroxyethylhexanoate, 1,1,3,3-tetramethylbutyl 2-peroxyethylhexanoate, 3-hydroxy-1,1-dimethylbutyl 2-peroxyethylhexanoate, tert-butyl peroxyisobutyrate, and mixtures thereof is selected from the group consisting of 8. An emulsion according to claim 1, characterized in that the peroxyester is preferably selected from the group consisting of tert-butyl peroxypivalate, tert-amyl peroxypivalate, tert-butyl peroxyneodecanoate, 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, tert-amyl peroxyneodecanoate and α-cumyl peroxydecanoate.

9. 9. Emulsion according to any one of claims 1 to 8, characterized in that the at least one antifreeze liquid is selected from the group consisting of ethanol, ethylene glycol, isopropanol, n-propanol, 1,2-propanediol, 1,3-propanediol, glycerol, 1-butanol, 2-butanol, 1,3-butanediol and 1,4-butanediol and mixtures thereof, preferably selected from the group consisting of isopropanol, ethanol, propanediol and mixtures thereof, more preferentially selected from the group consisting of ethanol and propanediol or mixtures thereof.

10. 10. The emulsion according to claim 1, wherein the emulsion is methanol-free.

11. 11. Emulsion according to any one of claims 1 to 10, characterized in that it contains between 5 and 25% by weight of antifreeze solution relative to the total weight of the aqueous emulsion, preferably 10% to 20% by weight.

12. 1. A method for preparing an aqueous emulsion of a peroxyester, comprising: at least one antifreeze; a combination of at least two emulsifiers selected from the group consisting of 1) non-ethoxylated sorbitan esters, 2) ethoxylated sorbitan esters, and 3) ethoxylated fatty alcohols; Water and at least one peroxyester; a) mixing the above components;

13. 12. Use of an emulsion according to any one of claims 1 to 11 for the polymerization of ethylenically unsaturated monomers.

14. 14. Use of a composition according to claim 13, characterized in that the ethylenically unsaturated monomer comprises vinyl chloride.

15. 12. A method for polymerizing ethylenically unsaturated monomers, comprising polymerizing in the presence of the emulsion of any one of claims 1 to 11.

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