Composition comprising at least one organic peroxide, at least one emulsifier, and at least one salt

Abstract

The present invention relates to a composition comprising at least one organic peroxide, at least one emulsifying agent, at least one salt, and water. The invention also relates to the use of a composition as defined above for polymerising or copolymerising one or more ethylenically unsaturated monomers, preferably one or more halogenated ethylenically unsaturated monomers, more preferably vinyl chloride. The present invention also relates to a halogenated vinyl polymer obtained by polymerising or copolymerising at least one halogenated ethylenically unsaturated monomer in the presence of at least one composition as defined above.

Description

[0001] DESCRIPTION

[0002] TITLE: Composition comprising at least one organic peroxide, at least one emulsifier, and at least one salt

[0003] The present invention relates to a composition comprising at least one organic peroxide, at least one emulsifying agent, at least one salt and water.

[0004] The invention also relates to the use of a composition as defined above for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, preferably one or more halogenated ethylenically unsaturated monomers, more preferably vinyl chloride.

[0005] The present invention also relates to a halogenated vinyl polymer obtained by polymerization or copolymerization of at least one halogenated ethylenically unsaturated monomer in the presence of at least one composition as defined above.

[0006] Organic peroxides, in liquid or solid form, are commonly used as polymerization initiators for ethylenically unsaturated monomers in the synthesis of various types of polymers. Organic peroxides can be peroxydicarbonates, peroxyesters or diacyl peroxides, peroxyketals, monoperoxycarbonates or dialkyl peroxides.

[0007] 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 storage temperature, certain organic peroxides may undergo self-accelerated exothermic decomposition likely to cause violent explosions and / or more or less serious fires. In addition, under these conditions, some of these organic peroxides may release combustible vapors that 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.In order to overcome these drawbacks, organic peroxides are packaged in the form of aqueous emulsions based on antifreeze. Thus, the presence of water allows both the absorption and dissipation of the energy generated in the event of possible exothermic decomposition of the organic peroxides, while the role of the antifreeze is to maintain the emulsion in liquid form, at temperatures well below 0°C, for example at temperatures below -10°C, or generally below -15°C, which makes it possible to prevent and / or limit the risks of involuntary exothermic decomposition of organic peroxides during storage and transport operations.

[0008] Aqueous emulsions generally also contain at least one emulsifying agent having 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. Thus, the role of the emulsifying agent is to stabilize the peroxide droplets in the aqueous phase. 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.

[0009] Furthermore, in addition to these safety considerations due to this destabilization phenomenon, the use of non-homogeneous aqueous emulsions of organic peroxide as a polymerization initiator in an emulsion or suspension of ethylenically unsaturated monomers can also generate points of heterogeneity within the final polymer product. These heterogeneities generally result in the presence of compact grain particles which are polymer particles poorly gelled during processing in the molten state (a phenomenon called "fish-eyes" in English; hard grains). However, the presence of hard grains opacifies the material obtained, which will impact its transparency, which can be a key criterion depending on the applications considered, particularly in medical applications, and / or its mechanical properties.

[0010] In view of the above, aqueous emulsions of organic peroxide must therefore be stable for safety reasons not only during their production but also during a relatively long period corresponding to their transport and storage before being used as polymerization initiators as well as for reasons related to the quality of the product obtained. Aqueous emulsions of organic peroxides generally comprise, as antifreeze agents, one or more alcohols soluble in water at room temperature having a low molecular weight, such as methanol or ethanol, especially methanol. The quantity of the antifreeze agent necessary to ensure a liquid emulsion at a given temperature below 0°C depends on its molecular mass. The quantity of methanol required is therefore lower than that of ethanol. At the same time, the volatility of alcohols decreases with molecular mass.To reduce the risk associated with the emulsion's flash point, it is necessary to choose an alcohol with a higher molecular weight. To maintain the emulsion's melting point at the same temperature, the amount of alcohol in the aqueous phase must be significantly increased, which leads to emulsion stability problems and increases the amount of organic molecules in the aqueous effluent from the polymerization process, which can create a high chemical oxygen demand (COD).

[0011] In addition, such antifreezes have the disadvantage of being volatile and of generating volatile organic compounds (VOCs) which can prove to be harmful to the health of operators, particularly during the various stages of handling aqueous emulsions of organic peroxides used for the synthesis of polymers obtained from one or more ethylenically unsaturated monomers. In other words, the presence of these antifreezes can also pose health and safety problems when handling aqueous emulsions of organic peroxides.

[0012] 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, in particular by proposing a composition capable of forming a reduced quantity of volatile organic compounds (VOCs) and organic molecules in aqueous effluents, thus reducing the chemical oxygen demand (COD).

[0013] In other words, one of the aims of the present invention is to propose a composition based on organic peroxide which poses fewer problems in terms of safety, in particular health, for operators than the aqueous emulsions of organic peroxides usually used for the synthesis of polymers obtained from ethylenically unsaturated monomers while being capable of being stable and homogeneous over time and having only a reduced quantity of organic molecules in the aqueous phase. In other words, one of the aims of the present invention is to propose a composition based on organic peroxide which is stable over time having improved qualities of use, in particular having a low viscosity, which also makes it possible to ensure good use of the organic peroxide during polymerization and in particular to facilitate all transfers of the emulsion both during its manufacture and its use.

[0014] The present invention therefore relates in particular to a composition comprising one or more organic peroxides in a content of 20 to 70% by weight, one or more emulsifiers, optionally one or more antifreeze agents, at least one salt and water.

[0015] The composition according to the invention thus has the advantage of posing fewer safety problems, particularly in terms of health, for operators than the aqueous emulsions of organic peroxides conventionally used during the synthesis of polymers obtained from ethylenically unsaturated monomers.

[0016] Indeed, the composition according to the invention generates fewer volatile organic compounds (VOCs) than the aqueous emulsions of organic peroxide conventionally used in the prior art, as well as a reduced quantity of organic molecules in the aqueous effluents of the polymerization process.

[0017] In particular, the composition according to the invention generates a lower chemical oxygen demand (COD) than the aqueous emulsions of organic peroxide conventionally used in the prior art.

[0018] Furthermore, the composition according to the invention also has the advantage of being stable and homogeneous at a temperature strictly below 0°C, preferably below -5°C, more preferably below -10°C.

[0019] In addition, the composition according to the invention has a low viscosity which allows a short flow time which makes it possible to facilitate the steps of unloading the emulsion into intermediate storage silos, pumping and introducing the organic peroxide emulsion into a polymerization reactor.

[0020] Furthermore, the composition according to the invention can have an average droplet size suitable for the application. Thus, the composition according to the invention can be transported and stored safely in polymer production units and lead to good quality polymeric materials.

[0021] The composition according to the invention has in particular the advantage of having droplets having a small average size with a narrow distribution. The invention also relates to the use of a composition as defined above for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, in particular one or more vinyl monomers, preferably halogenated, and more preferably vinyl chloride.

[0022] The composition according to the invention can therefore be used as polymerization initiators for the synthesis of polymers or copolymers obtained from one or more ethylenically unsaturated monomers.

[0023] Thus the composition is compatible with the polymerization or copolymerization of ethylenically unsaturated monomers, preferably vinyl monomers, more preferably halogenated vinyl monomers.

[0024] Furthermore, the invention also relates to a halogenated vinyl polymer obtained by polymerization or copolymerization of at least one halogenated ethylenically unsaturated monomer in the presence of the composition as defined above.

[0025] Other characteristics and advantages of the invention will appear more clearly on reading the description and examples which follow.

[0026] In what follows, and unless otherwise indicated, the limits of a domain of values ​​are included in this domain.

[0027] The expression "at least one" is equivalent to the expression "one or more".

[0028] Composition

[0029] The composition according to the invention comprises 20 to 70% by weight of one or more organic peroxides.

[0030] Preferably, the organic peroxide(s) is(are) selected from the group consisting of peroxy dicarbonates, peroxyesters, diacyl peroxides, peroxyketals, monoperoxycarbonates, dialkyl peroxides and mixtures thereof.

[0031] The organic peroxides may be peroxy dicarbonates, preferably selected from the group consisting of di-sec-butyl peroxydicarbonate, dibutyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis(3-methoxybutyl) peroxydicarbonate, bis(isobutyl) peroxydicarbonate, dineopentyl peroxydicarbonate, bis[2-(2-methoxyethoxyethyl)] peroxydicarbonate, bis(3-methoxy-3-methylbutyl) peroxydicarbonate, bis(2-ethoxyethyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, bis(1-methylheptyl) peroxydicarbonate, and mixtures thereof.

[0032] Preferably, the peroxydicarbonate is chosen from the group consisting of di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate and their mixture, more preferably di-sec-butyl peroxydicarbonate.

[0033] The organic peroxides may also be peroxyesters, preferably selected from the group consisting of tert-amyl peroxypivalate, tert-butyl peroxypivalate, tert-butyl peroxy isobutyrate, a-cumyl peroxyneodecanoate, a-cumyl peroxyneoheptanoate, 2,4,4 trimethylpentyl-2-peroxyneodecanoate, tert-butyl peroxyneoheptanoate, tert-amyl peroxy 2-ethylhexanoate, tert-butyl peroxy 2-ethylhexanoate, -1,1,3,3 tetramethyl butyl-peroxy-2 ethylhexanoate, tert-amyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, 1,1,3,3 tetramethylbutylperoxypivalate, 3-hydroxy-l,l-dimethylbutyl peroxyneodecanoate, tert-amyl peroxy n-heptanoate, tert-butyl peroxy n-heptanoate, tert-amyl peroxy n-octanoate, tert-butyl peroxy n-octanoate and mixtures thereof.

[0034] The organic peroxides may be diacyl peroxides, preferably selected from the group consisting of diisobutyroyl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, di(2-ethylhexanoyl) peroxide, di(n-heptanoyl) peroxide, as well as asymmetric peroxides such as isobutyroyl octanoyl peroxide, isobutyroyl decanoyl peroxide, isobutyroyl lauroyl peroxide, 2-ethylbutanoyl decanoyl peroxide, and mixtures thereof.

[0035] Preferably, the diacyl peroxides are selected from the group consisting of diisobutyroyl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, and mixtures thereof.

[0036] The organic peroxides may be peroxyketals, preferably selected from the group consisting of 1,1-di(tert-amyl peroxy)cyclohexane, 1,1-di(tert-butylperoxy)-3,3,5, trimethylcyclohexane), 2,2-di(4,4-di(tert-butylperoxy)cyclohexyl)propane, 1,1-di(tert-butylperoxy)-cyclohexane, 3,6,9- triethyl-3,6,9-trimethyl-1,4,7-triperoxonane and their mixture, preferably 1,1-di(tert-amyl peroxy)cyclohexane.

[0037] The organic peroxides may be monoperoxycarbonates, preferably selected from the group consisting of OO-tert-butyl O-isopropyl monoperoxycarbonate (TBIC), OO-tert-amyl O-isopropyl monoperoxycarbonate (TA-IPC), OO-tert-butyl-O-2-ethyl hexyl monoperoxycarbonate (TBEC) and OO-tert-amyl-O-2ethyl hexyl monoperoxycarbonate. The organic peroxides may be dialkyl peroxides preferably selected from the group consisting of 2,5-dimethyl 2,5-di(tert-butylperoxy)-hexane, tert-butyl cumyl peroxide, di-tert-amyl peroxide, di-tert-butyl peroxide and mixtures thereof.

[0038] Preferably, the organic peroxides are chosen from the group consisting of peroxydicarbonates, peroxyesters, diacyl peroxides and mixtures thereof.

[0039] Preferably, the organic peroxides are selected from the group consisting of di(2-ethylhexyl) peroxydicarbonate, for example sold under the trade name Luperox ® 223, di-sec-butyl peroxydicarbonate, for example sold under the trade name Luperox ® 225, and tert-butyl peroxypivalate, for example sold under the trade name Luperox ® 11.

[0040] Preferably, the organic peroxides are peroxydicarbonates, preferably di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate and their mixture, more preferably di(2-ethylhexyl) peroxydicarbonate.

[0041] Organic peroxides advantageously have a one-hour half-life temperature below 90°C.

[0042] In addition, organic peroxides advantageously have a storage temperature below 0°C.

[0043] Organic peroxides are advantageously liquid at storage temperature, preferably at a storage temperature below 0°C, measured at atmospheric pressure.

[0044] The organic peroxides are present in a content ranging from 20 to 70% by weight, preferably in a content ranging from 40 to 60% by weight, and more preferably from 45 to 60%, relative to the total weight of the composition.

[0045] The composition also comprises one or more emulsifying agents.

[0046] Preferably, the emulsifying agent may be a protective colloid agent, in particular selected from the group consisting of: a partially hydrolyzed polyvinyl acetate (PVA), a polyvinylpyrrolidone, a polyacrylate, a xanthan gum, a cellulose or a derivative thereof, in particular a methylcellulose, a carboxymethylcellulose, and a starch or a derivative thereof, and mixtures thereof, more preferably is selected from the group consisting of a partially hydrolyzed polyvinyl acetate (PVA), a xanthan gum, a methylcellulose, a carboxymethylcellulose and mixtures thereof, more preferably is a partially hydrolyzed polyvinyl acetate (PVA). Preferably, the partially hydrolyzed polyvinyl acetate has a degree of hydrolysis of 50 to 75% / mol.

[0047] Preferably, the emulsifying agent may also be a non-ionic surfactant and / or an ionic surfactant.

[0048] Preferably, the emulsifying agent is a non-ionic surfactant preferably chosen from the group consisting of oxyalkylenated (or alkoxylated) fatty alcohols, alkoxylated fatty acids, oxyalkylenated (or alkoxylated) vegetable or animal oils (hydrogenated or not), alkoxylated or non-alkoxylated sorbent esters, and mixtures thereof.

[0049] Preferably, the emulsifying agent(s) are chosen from the group consisting of a non-ionic surfactant, preferably chosen from the group consisting of oxyalkylenated fatty alcohols, alkoxylated fatty acids, oxyalkylenated (or alkoxylated) vegetable or animal oils (hydrogenated or not), alkoxylated or non-alkoxylated sorbitan esters and mixtures thereof.

[0050] 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.

[0051] Preferably, when the composition according to the invention comprises partially hydrolyzed polyvinyl acetate (PVA) then its content is preferably less than 0.5% by weight, more preferably less than 0.3% by weight, better still less than 0.2% by weight, relative to the total weight of the composition.

[0052] In a particularly preferred embodiment, the emulsifying agent is a mixture of a protective colloid agent, in particular a partially hydrolyzed polyvinyl acetate, and a non-ionic surfactant.

[0053] Preferably, when partially hydrolyzed polyvinyl acetate (PVA) is present in the composition according to the invention then its content is less than at least 0.2% by weight, relative to the total weight of the composition.

[0054] The emulsifying agent(s) may be present in the composition according to the invention in a content ranging from 0.05 to 10% by weight, preferably in a content ranging from 0.1 to 5% by weight, more preferably from 0.1 to 2% by weight, relative to the total weight of the composition.

[0055] In a particularly preferred embodiment, the composition does not comprise partially hydrolyzed polyvinyl acetate, preferably does not comprise a protective colloidal agent.

[0056] The composition may further comprise one or more antifreeze agents. For the purposes of the present invention, the term "antifreeze agent" means an agent, preferably a non-ionic agent, capable of lowering the melting point of water by at least 5°C and of maintaining an emulsion in liquid form at temperatures likely to be below -10°C, generally below -15°C.

[0057] For the purposes of the present invention, the antifreeze agent is in particular different from the salt as defined according to the invention.

[0058] Preferably, the antifreeze agent(s) are soluble in water at storage temperature.

[0059] By "soluble in water at storage temperature" is meant, for the purposes of the present invention, a compound having a solubility in water measured at a temperature ranging from -25 to 30°C of at least 0.1 gram / liter (g / l) (measured when the compound introduced into the water results in a macroscopically homogeneous and transparent solution), preferably a compound having a solubility in water measured at a temperature ranging from -25°C to at least 0.1 gram / liter (g / l).

[0060] Preferably, the antifreeze agent(s) have a molecular weight of less than 160 g / mol, preferably have a molecular weight of less than 100 g / mol.

[0061] Preferably, the antifreeze agent(s) are preferably chosen from the group consisting of monoalcohols, diols and triols.

[0062] Preferably, the antifreeze agent is chosen from the group consisting of C1-C6 alcohols, in particular C1-C4.

[0063] Preferably, the antifreeze agent is selected from the group consisting of C1-C6 alcohols, preferably 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, diethylene glycol, triethylene glycol and butan-1,4-diol and mixtures thereof, preferably ethanol.

[0064] The antifreeze agent is preferably present in the composition according to the invention in an antifreeze / water weight ratio of less than 1 / 1, preferably less than 1 / 2 by weight.

[0065] The composition according to the invention comprises at least one salt.

[0066] Said at least one salt is in particular different from a surfactant.

[0067] Preferably, said at least one salt is chosen from the group consisting of inorganic salts, organic salts and their mixtures.

[0068] Preferably, said at least one salt corresponds to the following chemical formula: ByA w (I)

[0069] Formula (I) in which: y is an integer ranging from 1 to 3, w is an integer ranging from 1 to 3,

[0070] A is an organic or inorganic anion,

[0071] B is a cation selected from the group consisting of alkali metal cations, alkaline earth metal cations and ammonium (NHC).

[0072] The salt respects F electroneutrality, that is to say that the absolute value of the sum of the negative charges of the anions is equal to the sum of the positive charges of the cations.

[0073] Preferably, in formula (I): w is equal to 1 or 2, y is equal to 1 or 2.

[0074] A may be an inorganic anion selected from the group consisting of nitrate (NO3'), carbonate (CO3 2'), halides, in particular chloride (CF), more preferably in the group consisting of nitrate (NO3 ) and halides, in particular chloride (CF).

[0075] A may be an organic anion selected from the group consisting of C1-C6 carboxylic acids, preferably C1-C4, preferably C1-C2, better still C2, in particular from a group consisting of C1-C6 carboxylic acids. Preferably, A may be a mineral anion selected from the group consisting of nitrate (NO3) and halides, in particular chloride (CF), or an organic anion selected from the group consisting of C1-C4 carboxylic acids, preferably C1-C2, better still C2 such as acetate (CH3COO).

[0076] More preferably, A is an inorganic anion, in particular chosen from the group consisting of nitrate (NO3) and halides, in particular chloride (CF).

[0077] Advantageously, B is a cation selected from the group consisting of alkali metal cations and alkaline earth metal cations.

[0078] Preferably, B is a cation selected from the group consisting of calcium ion (Ca 2+ ), the magnesium ion (Mg 2+ ), the sodium ion (Na + ), the potassium ion (K + ) and lithium ion (Li + ), especially calcium ion, sodium ion and lithium ion.

[0079] Advantageously, the salt is soluble in water at least 0.8 moles of ions per kilogram of water, preferably at least 0.9 moles of ions per kilogram of water, more preferably at least 1.35 moles of ions per kilogram of water, measured at a temperature of -5°C.

[0080] Preferably, said at least one salt is chosen from the group consisting of alkali metal salts, alkaline earth metal salts, ammonium salts and mixtures thereof.

[0081] Preferably, said at least one salt is chosen from the group consisting of calcium salts, magnesium salts, sodium salts, potassium salts, lithium salts and mixtures thereof, more preferably chosen from the group consisting of calcium salts, sodium salts, lithium salts and mixtures thereof.

[0082] Preferably, said at least one salt is selected from the group consisting of alkali metal halides, alkali metal acetates, alkali metal nitrates, alkali metal halides, and mixtures thereof.

[0083] More preferably, said at least one salt is chosen from the group consisting of sodium chloride, calcium chloride, sodium acetate, lithium nitrate and mixtures thereof.

[0084] Even more preferably, said at least one salt is an inorganic salt, in particular chosen from the group consisting of calcium chloride, sodium chloride, lithium nitrate and mixtures thereof.

[0085] In one embodiment, said at least one salt is not sodium hexametaphosphate, nor sodium carbonate, nor sodium hydroxide.

[0086] Preferably, the salt is present in a content ranging from 1 to 15% by weight, more preferably in a content ranging from 1 to 10% by weight, better still from 2 to 10% by weight, relative to the total weight of the composition.

[0087] Preferably, when the composition comprises at least one antifreeze, the weight ratio between the total content of antifreeze agent(s) and the total salt content varies from 0.1 to 10, more preferably varies from 0.5 to 5.

[0088] The composition according to the invention further comprises water, preferably in a content ranging from 15 to 58.9% by weight, relative to the total weight of the composition.

[0089] Preferably, the composition according to the invention comprises:

[0090] - 20 to 70% by weight of one or more organic peroxides chosen from the group consisting of peroxy dicarbonates, peroxyesters, diacyl peroxides, in particular peroxydicarbonates, and mixtures thereof, - one or more emulsifying agents, preferably chosen from the group consisting of non-ionic surfactants, protective colloidal agents and mixtures thereof,

[0091] - one or more antifreeze agents having a molecular weight of less than 160 g / mol, preferably a molecular weight of less than 100 g / mol, and soluble in water at room temperature, preferably chosen from the group consisting of C1-C6 alcohols, in particular C1-C4,

[0092] - at least one salt, and

[0093] - water.

[0094] Preferably, the composition according to the invention comprises:

[0095] - 20 to 70% by weight of one or more organic peroxides chosen from the group consisting of peroxy dicarbonates, preferably chosen from the group consisting of di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate and their mixture,

[0096] - one or more emulsifying agents chosen from the group consisting of non-ionic surfactants, protective colloidal agents and mixtures thereof,

[0097] - one or more antifreeze agents having a molecular weight of less than 160 g / mol, preferably a molecular weight of less than 100 g / mol and soluble in water at room temperature, preferably chosen from the group consisting of C1-C6 mono- and di-alcohols, in particular C1-C4,

[0098] - at least one salt, preferably chosen from the group consisting of alkali metal halides, alkali metal acetates, alkali metal nitrates, alkali metal halides and mixtures thereof, and

[0099] - water.

[0100] Preferably, the composition according to the invention comprises:

[0101] - 20 to 70% by weight of one or more organic peroxides chosen from the group consisting of peroxy dicarbonates, preferably di(2-ethylhexyl) peroxydicarbonate,

[0102] - one or more emulsifying agents chosen from the group consisting of non-ionic surfactants, protective colloidal agents and mixtures thereof

[0103] - one or more antifreeze agents chosen from the group consisting of C1-C6 mono- and di-alcohols, in particular C1-C4, in particular ethanol,

[0104] - at least one salt, preferably chosen from the group consisting of alkali metal halides, alkali metal acetates, alkali metal nitrates, alkali metal halides and mixtures thereof, and - optionally hydrogen peroxide,

[0105] - water.

[0106] The composition according to the invention may also comprise hydrogen peroxide.

[0107] 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.

[0108] The additive may be chosen from the group consisting of antioxidants; UV protection agents; processing agents, whose function is to improve the final appearance during its processing, such as fatty amides, stearic acid and its salts, ethylene bis-stearamide or fluorinated polymers; anti-fogging agents; anti-blocking agents such as silica or talc; nanofillers such as, for example, clays; coupling agents such as silanes; crosslinking agents such as peroxides other than the organic peroxides according to the invention; antistatic agents; nucleating agents; pigments; dyes; plasticizers; fluidizers.

[0109] The composition according to the invention may optionally contain one or more additives including chelating agents, biocides, for example fungicides, antiozonants, antioxidants, antidegradants, swelling agents and release agents.

[0110] The composition according to the invention may also contain additives usually used to stabilize organic peroxide or delay its decomposition such as phlegmatizers (isododecane, mineral oil, etc.) or hydroperoxides.

[0111] These additives may be added in the amounts usually used and known to those skilled in the art. These additives are generally used in amounts between 10 ppm and 10,000 ppm by weight relative to the final polymer weight. Plasticizers, plasticizers and flame retardant additives may reach amounts well above 10,000 ppm.

[0112] Preparation of the composition

[0113] The composition according to the invention can be prepared by dispersing at least the emulsifying agent, optionally one or more antifreeze agents, one or more salts, as defined above, and optionally one or more additives, in water to obtain an aqueous phase and then adding one or more organic peroxides to said aqueous phase, the whole then being emulsified during an emulsion step.

[0114] The above-mentioned steps may be carried out in the particular prescribed order or in a different order. Apart from the particular successive steps of the process for preparing the composition according to the invention, the preparation of the emulsion does not differ in any way from the techniques and apparatus well known to those skilled in the art.

[0115] The temperature at which the emulsion is prepared is not critical but must be low enough to avoid a significant rate of decomposition which would result in a loss of strength. The temperature chosen depends on the organic peroxide.

[0116] Preferably, the emulsion step is carried out at a temperature below 5°C (Celsius).

[0117] Furthermore, to prepare aqueous emulsions, deionized water or distilled water is conventionally used.

[0118] Preferably, the emulsion step is carried out with a high shear mixer to best divide and / or homogenize the peroxide in the aqueous phase. Examples include mechanically rotating paddle and anchor agitators, propeller agitators, i.e. one or more agitators mounted on a common shaft, and turbine agitators, i.e. those having fixed baffles on the mixing tank or positioned adjacent to the agitating members. Colloidal mills and homogenizers may also be used.

[0119] 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 pumping steps, the transfer into another container and / or the unloading at the end user, must be carried out as quickly as possible. This is why peroxide emulsions preferably have a low viscosity.

[0120] Preferably, the organic peroxide emulsions according to the invention have a flowability or flow time measured by a consistometric cutting technique of 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

[0121] The present invention also relates to the use of a composition 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.

[0122] Examples of ethylenically unsaturated monomers include acrylates, vinyl esters, vinyl halide monomers, vinyl ethers, butadiene, and aromatic vinyl compounds such as styrene.

[0123] Preferably, the ethylenically unsaturated monomers are chosen from the group consisting of vinyl halide monomers (i.e. halogenated vinyl monomers), in particular vinyl chloride or vinyl fluoride, and more preferably vinyl chloride.

[0124] Preferably, the polymerization or copolymerization is carried out with a suspension of the monomers to be polymerized.

[0125] The aqueous emulsion composition according to the invention can also be used in applications such as polymer modification reactions, crosslinking reactions, bulk polymerization reactions and curing processes as used in unsaturated polyester resins.

[0126] In particular, the aqueous emulsion composition according to the invention can also be used to modify the rheology of polymers, in particular polypropylene.

[0127] Polymer

[0128] Another subject of the present invention relates to the polymer, preferably a vinyl polymer, more preferably a halogenated vinyl polymer, obtained by polymerization or copolymerization of at least one ethylenically unsaturated monomer, as defined above, in the presence of the composition according to the invention as defined above.

[0129] Preferably, the invention relates to 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.

[0130] In particular, the polymerization of the vinyl chloride monomer occurs in suspension, preferably at an initiation temperature ranging from 45°C to 70°C. The following examples serve to illustrate the invention without, however, being limiting in nature.

[0131] EXAMPLES

[0132] Example 1

[0133] The following compositions A1, A2, A3, A4, A5, A6, A7, A8 and A9 are prepared according to the same procedure.

[0134] The aqueous phase containing the emulsifying agent (except Span® 80), namely the non-ionic surfactant and PVA, possibly the antifreeze agent, salt and water is stirred between 500 and 1000 revolutions per minute (rpm) and maintained at -5°C (Celsius).

[0135] The organic peroxides (with Span® 80 if applicable) are gradually added to the reactor containing this mixture. Stirring is maintained for three minutes at 2000 rpm. The mixture is then vigorously stirred using an "Ultraturrax type S-25N 18G" for eight minutes at 12500 rpm, then stirred using a paddle at 1000 rpm for one minute. Each emulsion is made on 200 grams in total. The compositions are then stored at a temperature of -20°C.

[0136] Tests carried out:

[0137] The droplet size is determined by conventional means using the light diffraction technique.

[0138] Measurements are made using a Malvern Master Sizer 3000® device at room temperature. D50, the average droplet size, represents the particle size for which 50% of the sample volume has a smaller particle size. D95 represents the particle size for which 95% of the sample volume has a smaller particle size. The D50 and D95 ​​measurements provide an indication of the particle size distribution within the emulsion.

[0139] Results are given with an accuracy of ± 0.5 pm (micrometer).

[0140] Viscosity was measured according to ASTM D1200 - LORD cup at a temperature of 5°C and is expressed in seconds. Compositions:

[0141] 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:

[0142] 5 [Table 1]

[0143] Results :

[0144] 5 At the time of production of the compositions

[0145] The results of average droplet size, droplet size distribution and viscosity at the time of production of compositions Al, A2, A3, A4, A5, A6, A7, A8 and A9 are grouped in Table 2 below:

[0146] 10

[0147] [Table 2]

[0148] The results show that the compositions according to the invention have droplets having a fine average size, including in the presence of hydrogen peroxide. It is also noted that the distribution of the size of the droplets is narrow, which reflects good homogeneity in the emulsions.

[0149] The compositions according to the invention also have a low viscosity which makes them easier to handle.

[0150] Stability of compositions Al to A9

[0151] The results of average droplet size, maximum droplet size

[0152] 25 droplets as well as the droplet size distribution determined over a period of one month at -20°C of the tested compositions are grouped in Table 3 below:

[0153] [Table 3]

[0154] It is found that the compositions according to the invention remain fluid at a temperature of -20°C.

[0155] The results show that the compositions according to the invention have an average droplet size, as well as a droplet size distribution that is virtually unchanged compared to those measured at the time of production of the composition.

[0156] These emulsions are therefore stable during storage, including in the presence of hydrogen peroxide in the emulsion.

[0157] The emulsions according to the invention advantageously make it possible to reduce the presence of alcohol in the emulsion, while maintaining a stable liquid emulsion at a temperature of -20°C.

[0158] Example 2

[0159] Compositions C1 to C5 were produced according to the protocol of example 1.

[0160] These compositions do not include salts. [Table 3]

[0161] Stability of compositions Cl to C5

[0162] After one week at -20°C, the compositions were visually studied: the appearance of crystals was observed in all compositions Cl to C5.

[0163] Such compositions cannot be pumped and are therefore difficult to use in a polymerization process.

Claims

CLAIMS 1. Composition comprising: - 20 to 70% by weight of one or more organic peroxides, - one or more emulsifiers, - possibly one or more antifreeze agents, - at least one salt and - water.

2. Composition according to claim 1, characterized in that the organic peroxides are chosen from the group consisting of peroxydicarbonates, peroxyesters, diacyl peroxides, peroxyketals, monoperoxycarbonates, dialkyl peroxides and their mixtures, preferably chosen from the group consisting of peroxydicarbonates, peroxyesters, diacyl peroxides and their mixtures, more preferably peroxydicarbonates.

3. Composition according to claim 1 or 2, characterized in that the organic peroxides are peroxydicarbonates chosen from the group consisting of di-sec-butyl peroxydicarbonate, dibutyl peroxydicarbonate, diisopropyl peroxydicarbonate, bis(3-methoxybutyl) peroxydicarbonate, bis(isobutyl) peroxydicarbonate, dineopentyl peroxydicarbonate, bis[2-(2-methoxyethoxy)ethyl] peroxydicarbonate, bis(3-methoxy-3-methylbutyl) peroxydicarbonate, bis(2-ethoxyethyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, bis(1-methylheptyl) peroxydicarbonate, and mixtures thereof, preferably chosen from the group consisting of di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate and mixtures thereof. blend.

4. Composition according to any one of claims 1 to 3, characterized in that the organic peroxides are peroxyesters chosen from the group consisting of tert-amyl peroxypivalate, tert-butyl peroxypivalate, tert-butyl peroxy isobutyrate, α-cumyl peroxyneodecanoate, α-cumyl peroxyneoheptanoate, 2,4,4 trimethylpentyl-2-peroxyneodecanoate, tert-butyl peroxyneoheptanoate, tert-amyl peroxy 2-ethylhexanoate, tert-butyl peroxy 2-ethylhexanoate, 1,1,3,3 tetramethyl butyl-peroxy-2 ethylhexanoate, tert-amyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, 1,1,3,3 tetramethylbutylperoxypivalate, 3-hydroxy-1,1-dimethylbutyl peroxyneodecanoate, tert-amyl peroxy n-heptanoate, tert-butyl peroxy n-heptanoate, tert-amyl peroxy n-octanoate, tert-butyl peroxy n-octanoate and mixtures thereof.

5. Composition according to any one of the preceding claims, characterized in that the organic peroxides are diacyl peroxides chosen from the group consisting of diisobutyroyl peroxide, di(3,5,5-trimethylhexanoyl) peroxide, di(2-ethylhexanoyl) peroxide, di(n-heptanoyl) peroxide, as well as asymmetric peroxides such as isobutyroyl octanoyl peroxide, isobutyroyl decanoyl peroxide, isobutyroyl lauroyl peroxide, 2-ethylbutanoyl decanoyl peroxide, and mixtures thereof.

6. Composition according to any one of the preceding claims, characterized in that the emulsifying agent(s) are chosen from the group consisting of: - a non-ionic surfactant, preferably chosen from the group consisting of oxyalkylenated fatty alcohols, alkoxylated fatty acids, oxyalkylenated vegetable or animal oils (hydrogenated or not), alkoxylated or non-alkoxylated sorbitan esters and mixtures thereof - a protective colloidal agent, in particular selected from the group consisting of: a partially hydrolyzed polyvinyl acetate, a polyvinylpyrollidone, a polyacrylate, a xanthan gum, a cellulose or a derivative thereof, in particular a methylcellulose, a carboxymethylcellulose, and a starch or a derivative thereof, and mixtures thereof, more preferably is selected from the group consisting of a partially hydrolyzed polyvinyl acetate, a xanthan gum, a methylcellulose, a carboxymethylcellulose and mixtures thereof, more preferably is a partially hydrolyzed polyvinyl acetate, - mixtures of these.

7. Composition according to any one of the preceding claims, characterized in that the antifreeze agent(s) have a molecular weight of less than 160 g / mol, preferably a molecular weight of less than 100 g / mol.

8. Composition according to any one of the preceding claims, characterized in that the antifreeze agent(s) are chosen from the group consisting of C1-C6 alcohols, preferably chosen 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.

9. Composition according to any one of the preceding claims, in which said at least one salt corresponds to the following formula: ByA w (I) Formula (I) in which: y is an integer ranging from 1 to 3, w is an integer ranging from 1 to 3, A is an organic or inorganic anion, B is a cation selected from the group consisting of alkali metal cations, alkaline earth metal cations and ammonium (NHC).

10. Composition according to any one of the preceding claims, characterized in that said at least one salt is chosen from the group consisting of alkali metal halides, alkali metal acetates, alkali metal nitrates, alkali metal halides, and mixtures thereof.

11. Composition according to any one of the preceding claims, in which said at least one salt is present in a content ranging from 1 to 15% by weight, more preferably in a content ranging from 2 to 10% by weight, relative to the total weight of the composition.

12. Composition according to any one of the preceding claims, comprising at least one antifreeze, the weight ratio between the total content of antifreeze agent(s) and the total salt content preferably ranging from 0.1 to 10, more preferably varying from 0.5 to 5.

13. Use of the composition as defined according to any one of the preceding claims for the polymerization or copolymerization of one or more ethylenically unsaturated monomers.

14. Use according to claim 13, characterized in that the ethylenically unsaturated monomers are halogenated vinyl monomers, preferably vinyl chloride.

15. Polymer, preferably vinyl polymer, more preferably halogenated vinyl polymer, obtained by polymerization of at least one ethylenically unsaturated monomer in the presence of the composition as defined according to any one of claims 1 to 12.

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