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 emulsifier, at least one salt, and water. The invention also relates to the use of a composition as defined above for polymerizing or copolymerizing one or more ethylenically unsaturated monomers, preferably one or more halogenated ethylenically unsaturated monomers, more preferably vinyl chloride. The invention also relates to halogenated vinyl polymers obtained by polymerizing or copolymerizing at least one halogenated ethylenically unsaturated monomer in the presence of at least one composition as defined above.

Description

Technical Field

[0001] The present invention relates to a composition comprising at least one organic peroxide, at least one emulsifier, at least one salt, and water.

[0002] 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, preferably one or more halogenated ethylenically unsaturated monomers, more preferably vinyl chloride.

[0003] The invention also relates to halovinyl polymers obtainable by polymerizing or copolymerizing at least one halovinically unsaturated monomer in the presence of at least one composition as defined above. Background Art

[0004] Organic peroxides in liquid or solid form are commonly used as initiators for the polymerization of ethylenically unsaturated monomers for the synthesis of various types of polymers. The organic peroxide may be a peroxydicarbonate, a peroxyester or a diacyl peroxide, a peroxyketal, a monoperoxycarbonate or a dialkyl peroxide.

[0005] The organic peroxide of the present invention is the organic peroxide of the present invention and has the advantages that: first, it can be used as the raw material of organic peroxide, and second, it can be used as the raw material of organic peroxide.Yet, there is a certain amount of problem in their use often.Particularly, organic peroxide is highly unstable material normally, because they decompose relatively easily under the effect of heat, mechanical energy (friction or impact) or incompatible pollutant of slight input.Therefore, when storage temperature uncontrolled ground raises, some organic peroxide may experience the self-accelerating exothermic decomposition that can cause violent explosion and / or relatively serious fire.In addition, under these conditions, some in these organic peroxides can discharge flammable vapor, and described flammable vapor can react with any ignition source, and this can sharply increase or even accelerate the risk of violent explosion.Therefore, it is important to take suitable preventive safety measures during storage and transportation organic peroxide.

[0006] In order to overcome these drawbacks, organic peroxides are packaged, in particular in the form of aqueous emulsions based on antifreeze agents. The presence of water thus makes it possible to absorb and dissipate the energy generated in the event of a possible exothermic decomposition of the organic peroxide, while the antifreeze agent serves to keep the emulsion in liquid form at temperatures well below 0° C., for example below −10° C., or even generally below −15° C., which makes it possible to prevent and / or limit the risk of unintentional exothermic decomposition of the organic peroxide during storage and transport operations.

[0007] Aqueous emulsions also typically contain at least one emulsifier, which has the advantage of reducing the interfacial tension between the aqueous phase and the organic peroxide, with the goal of promoting the dispersion of the peroxide in the form of droplets and maintaining the size of the droplets over time. Thus, the role of the emulsifier is to stabilize the peroxide droplets in the aqueous phase. This is because, over time, the peroxide droplets can aggregate, resulting in an increase in their median size and their maximum size, which in some cases can lead to complete or partial phase separation and, therefore, to overall destabilization of the emulsion.

[0008] Furthermore, in addition to these safety concerns due to this instability phenomenon, the use of non-homogeneous aqueous organic peroxide emulsions as polymerization initiators in emulsions or suspensions of ethylenically unsaturated monomers can also produce inhomogeneities in the final polymer product. These inhomogeneities are generally manifested as the presence of dense, fine particles, which are polymer particles that gel poorly during melt processing (a phenomenon known as "fish eyes"). However, the presence of fish eyes makes the resulting material opaque, and this will have an impact on its transparency, which may be a necessary requirement depending on the application in question (particularly in medical applications) and / or its mechanical properties.

[0009] In view of the above, aqueous organic peroxide emulsions must therefore be stable not only during their production but also over the relatively long periods corresponding to their transport and storage before use as polymerization initiators for safety reasons, and also for reasons relating to the quality of the products obtained.

[0010] Aqueous organic peroxide emulsions typically contain one or more alcohols that are soluble in water at room temperature and have a low molecular weight as antifreeze agents, such as methanol or ethanol, particularly methanol. The amount of antifreeze agent required to ensure a liquid emulsion at a given temperature below 0°C depends on its molecular weight. Therefore, the amount of methanol required is less than that of ethanol. At the same time, the volatility of alcohol decreases with molecular weight. In order to reduce the risks associated with the flash point of the emulsion, alcohols with higher molecular weights must be selected. In order to maintain the melting point of the emulsion at the same temperature, the amount of alcohol in the aqueous phase must be significantly increased, which leads to problems with emulsion stability and increases the amount of organic molecules found in the aqueous effluent from the polymerization process, which may lead to high chemical oxygen demand (COD).

[0011] Furthermore, such antifreeze agents have the disadvantage of being volatile and generating volatile organic compounds (VOCs) that can be harmful to the health of the operators, in particular during the various steps of handling the aqueous organic peroxide emulsions used to synthesize the polymers obtained from one or more ethylenically unsaturated monomers. In other words, the presence of these antifreeze agents can also cause health and safety problems when handling aqueous organic peroxide emulsions. Summary of the Invention

[0012] One of the objects of the present invention is therefore to provide a composition in the form of an aqueous organic peroxide emulsion which is stable and homogeneous over time, which is intended to be used as a polymerization initiator and which does not have the aforementioned drawbacks as regards the safety and quality of the products obtained, in particular by providing a composition capable of forming reduced amounts of volatile organic compounds (VOC) organic molecules in aqueous effluents, thereby reducing the chemical oxygen demand (COD).

[0013] In other words, one of the objects of the present invention is to provide a composition based on organic peroxides which, compared to the aqueous organic peroxide emulsions usually used for the synthesis of polymers obtained from ethylenically unsaturated monomers, poses fewer safety problems, in particular health problems, for the operators, while being stable and homogeneous over time and comprising only a reduced amount of organic molecules in the aqueous phase.

[0014] In other words, one of the objects of the present invention is to provide a composition based on an organic peroxide that is stable over time and has improved qualities in use, in particular a low viscosity; this also makes it possible to ensure good use of the organic peroxide during the polymerization and in particular to facilitate all transfers of the emulsion both during its production and during its use.

[0015] A subject of the present invention is therefore in particular a composition comprising one or more organic peroxides in an amount of 20% to 70% by weight, one or more emulsifiers, optionally one or more antifreeze agents, at least one salt and water.

[0016] The compositions according to the invention therefore have the advantage of causing fewer safety problems, in particular health problems, for operators compared to the aqueous organic peroxide emulsions usually used for the synthesis of polymers obtained from ethylenically unsaturated monomers.

[0017] In particular, the compositions according to the present invention produce fewer volatile organic compounds (VOCs) than the aqueous organic peroxide emulsions conventionally used in the prior art and also reduce the amount of organic molecules in the aqueous effluent from the polymerization process.

[0018] In particular, the compositions according to the invention generate a lower chemical oxygen demand (COD) than the aqueous organic peroxide emulsions conventionally used in the prior art.

[0019] Furthermore, the composition according to the invention has the advantage of being stable and homogeneous at temperatures strictly below 0°C, preferably below -5°C, more preferably below -10°C.

[0020] In addition, the composition according to the invention has a low viscosity, which allows short flow times, which makes it easier to carry out the steps of unloading the emulsion into intermediate storage silos, pumping, and introducing the organic peroxide emulsion into the polymerization reactor.

[0021] Furthermore, the composition according to the invention may have a median droplet size suitable for the application.Thus, the composition according to the invention may be safely transported and stored in polymer production units and result in polymer materials of good quality.

[0022] The compositions according to the invention have the particular advantage that the droplets have a small median size and a narrow distribution.

[0023] Another subject of the present invention is 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 vinyl monomers, more preferably vinyl chloride.

[0024] The composition according to the invention can therefore be used as a polymerization initiator for the synthesis of polymers or copolymers obtained from one or more ethylenically unsaturated monomers.

[0025] Thus, the composition is compatible with the polymerization or copolymerization of ethylenically unsaturated monomers, preferably vinyl monomers, more preferably halogenated vinyl monomers.

[0026] Furthermore, the present invention also relates to halovinyl polymers obtainable by polymerizing or copolymerizing at least one halovinically unsaturated monomer in the presence of a composition as defined above.

[0027] Other characteristics and advantages of the invention will become more apparent from reading the following description and examples.

[0028] Hereinafter, unless otherwise stated, the limits of a range of values ​​are included in the range.

[0029] The expression "at least one" is equivalent to the expression "one or more".

[0030] Composition

[0031] The composition according to the invention comprises from 20% to 70% by weight of one or more organic peroxides.

[0032] Preferably, the one or more organic peroxides are selected from the group consisting of peroxydicarbonates, peroxyesters, diacyl peroxides, peroxyketals, monoperoxycarbonates, dialkyl peroxides, and mixtures thereof.

[0033] The organic peroxide may be a peroxydicarbonate, 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-methoxyethoxy)ethyl] peroxydicarbonate, bis(3-methoxy-3-methylbutyl) peroxydicarbonate, bis(2-ethoxyethyl) peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, bis(1-methylheptyl) peroxydicarbonate, and mixtures thereof.

[0034] Preferably, the peroxydicarbonate is selected from di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate and mixtures thereof, more preferably di-sec-butyl peroxydicarbonate.

[0035] The organic peroxide may also be a peroxyester, preferably selected from the group consisting of tert-amyl peroxypivalate, tert-butyl peroxypivalate, tert-butyl peroxyisobutyrate, 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-tetramethylbutyl peroxy-2-ethylhexanoate, tert-amyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxypivalate, 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.

[0036] The organic peroxide may be a diacyl peroxide, preferably selected from diisobutyryl peroxide, di(3,5,5-trimethylhexanoyl)peroxide, di(2-ethylhexanoyl)peroxide, di(n-heptanoyl)peroxide, and also asymmetric peroxides such as isobutyryloctanoyl peroxide, isobutyryldecanoyl peroxide, isobutyryllauroyl peroxide, 2-ethylbutyryldecanoyl peroxide and mixtures thereof.

[0037] Preferably, the diacyl peroxide is selected from diisobutyryl peroxide, di(3,5,5-trimethylhexanoyl)peroxide and mixtures thereof.

[0038] The organic peroxide may be a peroxyketal, preferably selected from 1,1-di(tert-amylperoxy)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 mixtures thereof, and preferably 1,1-di(tert-amylperoxy)cyclohexane.

[0039] The organic peroxide may be a monoperoxycarbonate, preferably selected from OO-tert-butyl O-isopropyl monoperoxycarbonate (TBIC), OO-tert-amyl O-isopropyl monoperoxycarbonate (TA-IPC), OO-tert-butyl O-(2-ethylhexyl) monoperoxycarbonate (TBEC) and OO-tert-amyl O-(2-ethylhexyl) monoperoxycarbonate.

[0040] The organic peroxide may be a dialkyl peroxide, preferably selected from 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butylcumyl peroxide, di-tert-amyl peroxide, di-tert-butyl peroxide and mixtures thereof.

[0041] Preferably, the organic peroxide is selected from the group consisting of peroxydicarbonates, peroxyesters, diacyl peroxides and mixtures thereof.

[0042] Preferably, the organic peroxide is selected from 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.

[0043] Preferably, the organic peroxide is a peroxydicarbonate, preferably di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate and mixtures thereof, more preferably di(2-ethylhexyl) peroxydicarbonate.

[0044] The organic peroxide advantageously has a one hour half life temperature of less than 90°C.

[0045] Furthermore, the organic peroxide advantageously has a storage temperature below 0°C.

[0046] The organic peroxide is advantageously liquid at the storage temperature, preferably at a storage temperature below 0° C., measured at atmospheric pressure.

[0047] The organic peroxide is present in a content range of 20 to 70 wt %, preferably in a content range of 40 to 60 wt %, and more preferably in a content range of 45 to 60 wt %, relative to the total weight of the composition.

[0048] The composition also comprises one or more emulsifiers.

[0049] Preferably, the emulsifier can be a protective colloid, in particular selected from: partially hydrolyzed polyvinyl acetate (PVA), polyvinyl pyrrolidone, polyacrylate, xanthan gum, cellulose or its derivatives, in particular methylcellulose, carboxymethylcellulose and starch or its derivatives, and mixtures thereof, more preferably selected from partially hydrolyzed polyvinyl acetate (PVA), xanthan gum, methylcellulose, carboxymethylcellulose and mixtures thereof, more preferably partially hydrolyzed polyvinyl acetate (PVA).

[0050] Preferably, the partially hydrolyzed polyvinyl acetate has a degree of hydrolysis of 50 mol % to 75 mol %.

[0051] Preferably, the emulsifier may also be a nonionic surfactant and / or an ionic surfactant.

[0052] Preferably, the emulsifier is a nonionic surfactant, preferably selected from oxyalkylenated (or alkoxylated) fatty alcohols, alkoxylated fatty acids, oxyalkylenated (or alkoxylated) vegetable or animal oils (which are optionally hydrogenated), sorbitan esters (which are optionally alkoxylated) and mixtures thereof.

[0053] Preferably, the emulsifier is chosen from nonionic surfactants, preferably from oxyalkylenated fatty alcohols, alkoxylated fatty acids, oxyalkylenated (or alkoxylated) vegetable or animal oils (which are optionally hydrogenated), sorbitan esters (which are optionally alkoxylated) and mixtures thereof.

[0054] The oxyalkylenated units are more particularly ethylene oxide units (ie ethylene oxide groups), propylene oxide units (ie propylene oxide groups) or a combination thereof, preferably ethylene oxide units or a combination of ethylene oxide units and propylene oxide units.

[0055] When the composition according to the invention contains partially hydrolyzed polyvinyl acetate (PVA), it is preferred that 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.

[0056] In a particularly preferred embodiment, the emulsifier is a mixture of a protective colloid, in particular partially hydrolyzed polyvinyl acetate, and a nonionic surfactant.

[0057] When partially hydrolyzed polyvinyl acetate (PVA) is present in the composition according to the invention, its content is preferably less than at least 0.2% by weight relative to the total weight of the composition.

[0058] The emulsifier may be present in the composition according to the invention in an amount ranging from 0.05% to 10% by weight, preferably from 0.1% to 5% by weight, more preferably from 0.1% to 2% by weight relative to the total weight of the composition.

[0059] In a particularly preferred embodiment, the composition comprises no partially hydrolyzed polyvinyl acetate and preferably no protective colloids.

[0060] The composition may further comprise one or more antifreeze agents.

[0061] For the purposes of the present invention, "antifreeze" is understood to mean an agent, preferably a non-ionic agent, capable of lowering the melting temperature of water by at least 5°C and maintaining the emulsion in liquid form at temperatures which may be below -10°C, typically below -15°C.

[0062] For the purposes of the present invention, antifreeze agents are in particular distinguished from salts as defined according to the invention.

[0063] Preferably, the antifreeze agent is soluble in water at the storage temperature.

[0064] For the purposes of the present invention, "soluble in water at storage temperature" is understood to mean a compound having a solubility in water of at least 0.1 gram per liter (g / l) measured in a temperature range of -25°C to 30°C (measured when the compound introduced into water results in a macroscopically homogeneous and transparent solution being obtained), preferably a compound having a solubility in water of at least 0.1 gram per liter (g / l) measured in a temperature range of -25°C to 30°C.

[0065] Preferably, the antifreeze agent has a molecular weight of less than 160 g / mol, preferably less than 100 g / mol.

[0066] Preferably, the antifreeze agent is selected from monohydric alcohols, dihydric alcohols and trihydric alcohols.

[0067] Preferably, the antifreeze agent is selected from C1-C6 alcohols, in particular C1-C4 alcohols.

[0068] Preferably, the antifreeze agent is selected from C1-C6 alcohols, preferably selected from methanol, ethanol, ethylene glycol, isopropanol, n-propanol, propane-1,2-diol, propane-1,3-diol, glycerol, butane-1-ol, butane-2-ol, butane-1,3-diol, diethylene glycol, triethylene glycol, and butane-1,4-diol and mixtures thereof, preferably ethanol.

[0069] The antifreeze agent is preferably present in the composition according to the invention in an antifreeze agent / water weight ratio of less than 1 / 1 by weight, preferably less than 1 / 2 by weight.

[0070] The composition according to the invention comprises at least one salt.

[0071] The at least one salt is in particular different from a surfactant.

[0072] Preferably, the at least one salt is selected from inorganic salts, organic salts and mixtures thereof.

[0073] Preferably, the at least one salt corresponds to the following formula:

[0074] B y A w (I)

[0075] Formula (I), wherein:

[0076] y is an integer ranging from 1 to 3,

[0077] w is an integer ranging from 1 to 3,

[0078] A is an organic or inorganic anion,

[0079] B is selected from alkali metal cations, alkaline earth metal cations and ammonium cations (NH4 + ) cations.

[0080] The salt is observed to be electrically neutral, ie 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.

[0081] Preferably, in formula (I):

[0082] w is equal to 1 or 2,

[0083] y is equal to 1 or 2,

[0084] A can be an inorganic anion selected from nitrate (NO3 - ), carbonate (CO3 2- ), halogen ions, especially chloride ions (Cl - ), more preferably selected from nitrate (NO3 - ) and halide ions, especially chloride ions (Cl - ).

[0085] A can be an organic anion selected from C1-C6 carboxylic acids, preferably C1-C4 carboxylic acids, preferably C1-C2 carboxylic acids, better still C2 carboxylic acids, in particular selected from C1-C6 carboxylic acids. Preferably, A can be selected from nitrate (NO3 - ) and halide ions, especially chloride ions (Cl -) or an inorganic anion selected from C1-C4 carboxylic acids, preferably C1-C2 carboxylic acids, and better still C2 carboxylic acids, such as acetate (CH3COO-).

[0086] More preferably, A is an inorganic anion, in particular selected from nitrate (NO3 - ) and halide ions, especially chloride ions (Cl - ).

[0087] B is advantageously a cation selected from alkali metal cations and alkaline earth metal cations.

[0088] Preferably, B is selected from calcium ions (Ca 2+ ), magnesium ions (Mg 2+ ), sodium ion (Na + ), potassium ion (K + ) and lithium ion (Li + ) cations, especially calcium ions, sodium ions and lithium ions.

[0089] The salt is advantageously soluble in water to the extent of at least 0.8 mol ions per kg of water, preferably at least 0.9 mol ions per kg of water, more preferably at least 1.35 mol ions per kg of water, measured at a temperature of -5°C.

[0090] Preferably, the at least one salt is selected from alkali metal salts, alkaline earth metal salts, ammonium salts and mixtures thereof.

[0091] Preferably, the at least one salt is selected from calcium salts, magnesium salts, sodium salts, potassium salts, lithium salts and mixtures thereof, more preferably selected from calcium salts, sodium salts, lithium salts and mixtures thereof.

[0092] Preferably, the 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.

[0093] More preferably, the at least one salt is selected from sodium chloride, calcium chloride, sodium acetate, lithium nitrate, and mixtures thereof.

[0094] Even more preferably, said at least one salt is an inorganic salt, in particular chosen from calcium chloride, sodium chloride, lithium nitrate and mixtures thereof.

[0095] In one embodiment, the at least one salt is not sodium hexametaphosphate, sodium carbonate, or sodium hydroxide.

[0096] Preferably, the salt is present in a content ranging from 1% to 15% by weight, more preferably from 1% to 10% by weight, better still from 2% to 10% by weight relative to the total weight of the composition.

[0097] When the composition comprises at least one antifreeze agent, it is preferred that the weight ratio between the total content of antifreeze agents and the total content of salts ranges from 0.1 to 10, more preferably from 0.5 to 5.

[0098] 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.

[0099] Preferably, the composition according to the invention comprises:

[0100] - 20% to 70% by weight of one or more organic peroxides chosen from peroxydicarbonates, peroxyesters and diacylperoxides, in particular peroxydicarbonates and mixtures thereof,

[0101] - one or more emulsifiers, preferably selected from nonionic surfactants, protective colloids and mixtures thereof,

[0102] one or more antifreeze agents having a molecular weight of less than 160 g / mol, preferably less than 100 g / mol, and soluble in water at room temperature, preferably selected from C1-C6 alcohols, especially C1-C4 alcohols,

[0103] - at least one salt, and

[0104] -water.

[0105] Preferably, the composition according to the invention comprises:

[0106] - 20% to 70% by weight of one or more organic peroxides selected from the group consisting of peroxydicarbonates, preferably selected from di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate and mixtures thereof,

[0107] - one or more emulsifiers selected from nonionic surfactants, protective colloids and mixtures thereof,

[0108] one or more antifreeze agents having a molecular weight of less than 160 g / mol, preferably less than 100 g / mol, and soluble in water at room temperature, preferably selected from C1-C6 monoalcohols and diols, in particular C1-C4 monoalcohols and diols,

[0109] at least one salt, preferably selected from alkali metal halides, alkali metal acetates, alkali metal nitrates, alkali metal halides and mixtures thereof, and

[0110] -water.

[0111] Preferably, the composition according to the invention comprises:

[0112] - 20% to 70% by weight of one or more organic peroxides chosen from peroxydicarbonates, preferably di(2-ethylhexyl)peroxydicarbonate,

[0113] - one or more emulsifiers selected from nonionic surfactants, protective colloids and mixtures thereof,

[0114] one or more antifreeze agents selected from C1-C6 mono- and diols, especially C1-C4 mono- and diols, in particular ethanol,

[0115] - at least one salt, preferably selected from alkali metal halides, alkali metal acetates, alkali metal nitrates, alkali metal halides and mixtures thereof, and

[0116] - optionally hydrogen peroxide,

[0117] -water.

[0118] The composition according to the invention may also comprise hydrogen peroxide.

[0119] The composition according to the invention may also contain one or more additives intended to impart specific properties / characteristics to the final composition. These additives will ideally be present for the final polymerization or copolymerization.

[0120] The additives may be selected from antioxidants; UV protectants; processing agents which, when used, have the function of improving the final appearance, such as fatty amides, stearic acid and its salts, ethylenebis(stearamide) or fluoropolymers; antifogging agents; antiblocking agents, such as silica or talc; nanofillers, such as 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; fluidizing agents.

[0121] The compositions according to the present invention may optionally contain one or more additives including chelating agents, biocides such as fungicides, antiozonants, antioxidants, antidegradants, swelling agents and release agents.

[0122] The composition according to the invention may also contain additives usually used to stabilize organic peroxides or to delay their decomposition, such as phlegmatizers (isododecane, mineral oil, etc.) or hydroperoxides.

[0123] These additives can be added in amounts commonly 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 weight of the final polymer. Plasticizers, fluidizers and flame retardant additives can be added in amounts far exceeding 10,000 ppm.

[0124] Preparation of composition

[0125] The composition according to the invention can be prepared by dispersing at least the emulsifier, 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, then adding one or more organic peroxides to said aqueous phase and then emulsifying the whole during an emulsification step.

[0126] The above steps can be performed in the specific order specified or in a different order. Apart from the specific successive steps of the process (method, process) for preparing the composition according to the invention, the preparation of the emulsion is no different in any respect from the techniques and equipment well known to those skilled in the art.

[0127] The temperature at which the emulsion is prepared is not critical, but it must be low enough to avoid high levels of decomposition which would result in a loss of titer. The temperature chosen depends on the organic peroxide.

[0128] Preferably, the emulsification step is performed at a temperature below 5°C (degrees Celsius).

[0129] Furthermore, deionized water or distilled water is conventionally used to prepare aqueous emulsions.

[0130] Preferably, the emulsification step is carried out using a high shear mixer to separate and / or homogenize the peroxide in the aqueous phase as much as possible. Examples include paddle and anchor stirrers with mechanical rotation, impeller stirrers, i.e., stirrers with one or more stirrers mounted on a common shaft, and turbine stirrers, i.e., stirrers with baffles fixed to the mixing vessel or adjacent to the stirring element. Colloid mills and homogenizers may also be used.

[0131] 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. After the emulsion is prepared, the steps of pumping, transferring to another container and / or unloading at the end user should be carried out as quickly as possible. This is why the peroxide emulsion preferably has a low viscosity.

[0132] Preferably, the organic peroxide emulsion according to the invention has a fluidity or flow time of less than 200 seconds, preferably less than 100 seconds, measured by the consistometer cup technique (DIN 53211, viscosity cup diameter 4 mm, temperature 5° C.). In the context of the present invention, the subsequent polymerization or copolymerization steps do not differ from those of the prior art.

[0133] use

[0134] 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 one or more vinyl monomers, preferably halogenated vinyl monomers and more preferably vinyl chloride.

[0135] Ethylenically unsaturated monomers include acrylates, vinyl esters, vinyl halide monomers, vinyl ethers, butadiene, and vinyl aromatic compounds such as styrene.

[0136] Preferably, the ethylenically unsaturated monomer is selected from vinyl halide monomers (ie, halovinyl monomers), in particular vinyl chloride or vinyl fluoride, more preferably vinyl chloride.

[0137] Preferably, the polymerization or copolymerization is carried out with a suspension of the monomers to be polymerized.

[0138] The aqueous emulsion composition according to the present invention can also be used in applications such as use in unsaturated polyester resins, such as polymer modification reactions, crosslinking reactions, bulk polymerization reactions, and curing processes.

[0139] In particular, the aqueous emulsion compositions according to the invention can also be used to modify the rheological properties of polymers, in particular polypropylene.

[0140] polymer

[0141] Another subject of the present invention relates to polymers, preferably vinyl polymers, more preferably halogenovinyl polymers, obtained by polymerizing or copolymerizing at least one ethylenically unsaturated monomer as defined above in the presence of a composition according to the invention as defined above.

[0142] Preferably, the invention relates to poly(vinyl chloride) obtained by polymerization of vinyl chloride in the presence of a composition according to the invention, in particular a mixture of organic peroxides as defined above.

[0143] In particular, the polymerization of vinyl chloride monomer is carried out in suspension, preferably at an initiation temperature in the range of 45°C to 70°C.

[0144] The following examples are intended to illustrate the present invention but are not limiting in nature. Example

[0145] Example 1

[0146] The following compositions A1, A2, A3, A4, A5, A6, A7, A8 and A9 were prepared according to the same procedure.

[0147] The aqueous phase containing the emulsifier (except Span® 80), i.e., nonionic surfactant, and PVA, optionally antifreeze, salt and water is stirred at 500 to 1000 revolutions per minute (rpm) and maintained at -5°C (degrees Celsius).

[0148] An organic peroxide (including Span® 80, if appropriate) was gradually added to the reactor containing the mixture. Agitation was maintained at 2000 rpm for 3 minutes. The entire mass was then vigorously stirred at 12,500 rpm for 8 minutes using an Ultra-Turrax S-25N 18G, followed by stirring with a paddle at 1000 rpm for 1 minute. A total of 200 g was emulsified per time. The composition was then stored at -20°C.

[0149] Tests performed:

[0150] Droplet size is determined by conventional means using light scattering techniques.

[0151] Measurements were taken at room temperature using a Malvern MasterSizer 3000® instrument. The D50, or median droplet size, represents the particle size at which 50% of the sample volume has a smaller particle size. The D95 represents the particle size at which 95% of the sample volume has a smaller particle size. The D50 and D95 ​​measurements give an indication of the particle size distribution within the emulsion.

[0152] The results are given with an accuracy of ±0.5 μm (micrometer).

[0153] Viscosity was measured using a Ford viscosity cup at a temperature of 5°C according to ASTM D1200 and is expressed in seconds.

[0154] Composition:

[0155] The amounts of the following ingredients are expressed in Table 1 below as weight percentages relative to the total weight of the composition:

[0156] [Table 1]

[0157]

[0158] result:

[0159] When producing the composition

[0160] The results for median droplet size, droplet size distribution and viscosity when producing compositions A1, A2, A3, A4, A5, A6, A7, A8 and A9 are collated in Table 2 below:

[0161] [Table 2]

[0162]

[0163] The results show that the composition according to the invention has a fine median size of droplets, including in the presence of hydrogen peroxide. The droplets were also found to have a narrow size distribution, which is a reflection of good homogeneity in the emulsion.

[0164] The compositions according to the invention also have a low viscosity, which makes them easier to handle.

[0165] Stability of compositions A1 to A9

[0166] The results of the median droplet size, maximum droplet size and droplet size distribution of the test compositions measured at -20°C over a period of one month are collated in Table 3 below:

[0167] [Table 3]

[0168]

[0169] The composition according to the invention was found to remain fluid at a temperature of -20°C.

[0170] The results show that the compositions according to the present invention have median droplet sizes and droplet size distributions that are little changed from those measured when the compositions were produced.

[0171] Thus, these emulsions are stable upon storage, including when hydrogen peroxide is present in the emulsion.

[0172] The emulsion according to the invention advantageously makes it possible to reduce the amount of alcohol in the emulsion while keeping the liquid emulsion stable at a temperature of -20°C.

[0173] Example 2

[0174] Compositions C1 to C5 were produced according to the protocol of Example 1. These compositions did not contain salt.

[0175] [Table 3]

[0176]

[0177] Stability of compositions C1 to C5

[0178] After one week at -20°C, the compositions were visually inspected: the appearance of crystals was observed in all compositions C1 to C5.

[0179] Such compositions are not pumpable and are therefore difficult to use in polymerization processes.

Claims

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

2. The composition according to claim 1, characterized in that The organic peroxide is selected from peroxydicarbonates, peroxyesters, diacyl peroxides, peroxyketals, monoperoxycarbonates, dialkyl peroxides and mixtures thereof, preferably selected from peroxydicarbonates, peroxyesters, diacyl peroxides and mixtures thereof, more preferably peroxydicarbonates.

3. The composition according to claim 1 or 2, characterized in that The organic peroxide is a peroxydicarbonate selected from 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 selected from di(2-ethylhexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate and mixtures thereof.

4. The composition according to any one of claims 1 to 3, characterized in that The organic peroxide is a peroxyester selected from the group consisting of tert-amyl peroxypivalate, tert-butyl peroxypivalate, tert-butyl peroxyisobutyrate, 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-tetramethylbutyl peroxy-2-ethylhexanoate, tert-amyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxypivalate, 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. The composition according to any one of the preceding claims, characterized in that The organic peroxide is a diacyl peroxide selected from the group consisting of diisobutyryl peroxide, di(3,5,5-trimethylhexanoyl)peroxide, di(2-ethylhexanoyl)peroxide, di(n-heptanoyl)peroxide, and also asymmetric peroxides such as isobutyryloctanoyl peroxide, isobutyryldecanoyl peroxide, isobutyryllauroyl peroxide, 2-ethylbutyryldecanoyl peroxide, and mixtures thereof.

6. A composition according to any one of the preceding claims, characterised in that The emulsifier is selected from: - nonionic surfactants, preferably chosen from oxyalkylenated fatty alcohols, alkoxylated fatty acids, oxyalkylenated vegetable or animal oils (which are optionally hydrogenated), sorbitan esters, which are optionally alkoxylated, and mixtures thereof, a protective colloid, in particular selected from the group consisting of partially hydrolyzed polyvinyl acetate, polyvinyl pyrrolidone, polyacrylates, xanthan gum, cellulose or its derivatives, in particular methylcellulose, carboxymethylcellulose and starch or its derivatives, and mixtures thereof, more preferably selected from the group consisting of partially hydrolyzed polyvinyl acetate, xanthan gum, methylcellulose, carboxymethylcellulose and mixtures thereof, more preferably partially hydrolyzed polyvinyl acetate, - mixtures thereof.

7. A composition according to any one of the preceding claims, characterised in that The antifreeze agent has a molecular weight of less than 160 g / mol, preferably less than 100 g / mol.

8. The composition according to any one of the preceding claims, characterized in that The antifreeze agent is selected from C1-C6 alcohols, preferably selected from methanol, ethanol, ethylene glycol, isopropanol, n-propanol, propane-1,2-diol, propane-1,3-diol, glycerol, butane-1-ol, butane-2-ol, butane-1,3-diol and butane-1,4-diol and mixtures thereof.

9. The composition according to any one of the preceding claims, wherein the at least one salt corresponds to the formula: B y A w (I) Formula (I), wherein: 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 selected from alkali metal cations, alkaline earth metal cations and ammonium cations (NH4 + ) cations.

10. The composition according to any one of the preceding claims, characterized in that The 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.

11. The composition according to any one of the preceding claims, wherein the at least one salt is present in an amount ranging from 1% to 15% by weight, more preferably from 2% to 10% by weight relative to the total weight of the composition.

12. The composition according to any one of the preceding claims, comprising at least one antifreeze agent, the weight ratio between the total content of antifreeze agent and the total salt content preferably being in the range of 0.1 to 10, more preferably in the range of 0.5 to 5.

13. Use of a composition as defined in any one of the preceding claims for the polymerisation or copolymerisation of one or more ethylenically unsaturated monomers.

14. The use according to claim 13, characterized in that The ethylenically unsaturated monomer is a halogenated vinyl monomer, preferably vinyl chloride.

15. A polymer, preferably a vinyl polymer, more preferably a halogenovinyl polymer, obtained by polymerizing at least one ethylenically unsaturated monomer in the presence of a composition as defined in any one of claims 1 to 12.

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