Aqueous composition comprising at least one organic peroxide and at least one oxyalkylated fatty alcohol

Abstract

The present invention relates to an aqueous suspension comprising at least one linear diacyl peroxide and at least one oxyalkylated fatty alcohol having an HLB value of less than or equal to 16. The invention also relates to the use of at least one aqueous suspension, as described above, for the polymerization or copolymerization of one or more ethylenically unsaturated monomers, preferably halogenated, and more preferably vinyl chloride.

Description

[0001] DESCRIPTION

[0002] TITLE: Aqueous composition comprising at least one organic peroxide and at least one oxyalkylated fatty alcohol

[0003] The present invention relates to a composition in the form of an aqueous suspension comprising at least one linear diacyl peroxide and at least one oxyalkylated fatty alcohol having an HLB value less than or equal to 16.

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

[0005] Similarly, the present invention also relates to a process for preparing a polymer or a copolymer comprising one or more motifs derived from halogenated ethylenic unsaturation monomers, comprising at least one step of polymerizing at least one halogenated ethylenic unsaturation monomer, optionally in a mixture with at least one ethylenic unsaturation comonomer, in a composition as defined above.

[0006] Organic peroxides, such as peroxydicarbonates, peroxyesters and diacyl peroxides, are generally used as initiators for the polymerization or copolymerization of ethylenically unsaturated monomers, for example halogenated ethylenically unsaturated monomers, especially vinyl chloride.

[0007] However, their handling frequently presents a number of difficulties. Indeed, organic peroxides are most often highly unstable species because they decompose relatively easily under the influence of even a small amount of heat, mechanical energy (friction or impact), or incompatible contaminants. Thus, in the event of an uncontrolled rise in their storage temperature, some organic peroxides can undergo self-accelerating exothermic decomposition, potentially leading to fires and / or violent explosions. Furthermore, under these conditions, some of these organic peroxides can release combustible vapors that can react with any ignition source, which can drastically increase, or even accelerate, the risk of a violent explosion. Consequently, it is crucial to take appropriate safety precautions during the storage and transport of organic peroxides.

[0008] To overcome such drawbacks, organic peroxides are formulated with an organic solvent (phlegmatizing agent) or are packaged as a suspension or emulsion in water to prevent and / or limit the risks of unintentional exothermic decomposition of organic peroxides which can occur not only during their production but also over a relatively long period corresponding to their storage and / or transport before being used as polymerization initiators.

[0009] In particular, in suspensions, the presence of water offers the advantage of absorbing and dissipating the energy generated in the event of exothermic decomposition of organic peroxides. Thus, in the event of decomposition, it will occur without a major risk of fire because water constitutes a powerful reservoir for absorbing heat, unlike an organic solvent which is likely to ignite under these conditions.

[0010] In addition, aqueous suspensions of organic peroxide have the advantage of being pumpable, making them easier to transport and / or store safely.

[0011] In particular, dilauroyl peroxide is found in solid form and has a type D classification according to UN recommendations, while an aqueous suspension of such peroxide at a concentration of 40% active ingredients has a type F classification. Such a type F classification allows it to be transported in IBCs and stored in tanks in large quantities.

[0012] Furthermore, the steps of unloading these formulations into intermediate storage silos, pumping and introducing these formulations into a polymerization reactor are important steps for the quality and properties of the polymer or copolymer obtained as well as the reliability of the polymerization or copolymerization process.

[0013] These handling steps generally need to be implemented as quickly as possible. To achieve this, it is important that such formulations have a low viscosity so that their flow within the polymerization reactor is maximized and they are easier to pump. At a given temperature, the viscosity of this type of suspension varies particularly with the shear rate.

[0014] Indeed, it has been observed that the implementation of certain suspending agents, or suspension systems, is likely to lead to a significant increase in the viscosity over time of these formulations, for example an increase of more than 50% of their initial viscosity only two months after their preparation, which accentuates their flow time within the polymerization reactor and causes significant pumpability problems, thus impacting not only the costs and / or production time but also the quality and properties of the polymers or copolymers prepared, in particular polymers or copolymers obtained from halogenated ethylenic unsaturated monomers, especially vinyl chloride.

[0015] In view of the foregoing, one of the objectives of the present invention is therefore to propose an aqueous composition based on organic peroxide, intended to be used as polymerization initiators, which does not have the disadvantages previously described, i.e. having in particular a sufficiently low viscosity and stable over time, for example for a period of at least two months, allowing good use of said composition, in particular a short flow time of the composition and good pumpability.

[0016] In particular, one of the aims of the present invention is to propose an aqueous composition of organic peroxide having a sufficiently low viscosity and stable over time, capable of leading to a polymer or copolymer having a satisfactory quality.

[0017] The present invention therefore relates in particular to a composition in the form of an aqueous suspension comprising:

[0018] at least one linear diacyl peroxide and

[0019] - at least one oxyalkylated fatty alcohol having an HLB value less than or equal to 16.

[0020] In other words, the composition according to the invention is an aqueous suspension comprising at least one linear diacyl peroxide and at least one oxyalkylated fatty alcohol having an HLB value less than or equal to 16.

[0021] The composition according to the invention thus has the advantage of having a low viscosity and stable over time, in particular during a period of at least two months at room temperature, thus allowing a short flow time and maintaining good pumpability while maintaining good dispersion of the organic peroxide in the water.

[0022] The composition according to the invention thus has a low viscosity that is likely to vary only slightly over time, in particular over a period of at least two months at room temperature, which makes it possible to guarantee good use, in particular short flow times.

[0023] The composition according to the invention has, in particular, a viscosity at room temperature of less than or equal to 600 mPa.s, preferably less than or equal to 500 mPa.s, at a shear rate greater than 100 s⁻¹ 1 , while varying by 50% or less of its initial value, more preferably by less than 30% of its initial value, even more preferably by less than 20% of its initial value, better by less than 15% of its initial value, for a period of at least two months at room temperature.

[0024] In particular, the composition according to the invention exhibits a lower viscosity, whether after production or after a storage period of at least two months at room temperature, than those measured for a composition comprising the same organic peroxide mixed with at least one oxyalkylated fatty alcohol having an HLB value strictly greater than 16, at a shear rate greater than 100 s' 1 .

[0025] Furthermore, advantageously, the composition according to the invention has a viscosity less than or equal to 500 mPa.s, at a shear rate greater than 100 s' 1, while varying by less than 15% of its initial value, for a period of at least two months at room temperature, whereas over the same period of time the viscosity of a composition comprising the same organic peroxide mixed with at least one oxyalkylated fatty alcohol having an HLB value strictly greater than 16, can vary by more than 50%, or even nearly 70%, of its initial value, considerably affecting flow times in the polymerization reactor and ease of pumping.

[0026] Dynamic viscosity measurements can be performed using coaxial cylinders that create shear, for example according to DIN 53019.

[0027] The composition according to the invention has a low and stable viscosity over time allowing a short flow time which facilitates the steps of unloading the composition into intermediate storage silos, pumping and introducing said composition into a polymerization reactor including after a storage period of at least two months at room temperature.

[0028] Thus the composition according to the invention can be used either immediately after its preparation or after a storage period of at least two months at room temperature without its flow properties being affected, in particular without the steps of unloading, pumping and / or introducing the composition into a polymerization reactor being affected.

[0029] In other words, the composition according to the invention offers greater flexibility to operators in its use for the polymerization of monomers with ethylenic unsaturation, in particular compared to a composition comprising the same organic peroxide mixed with at least one oxyalkylated fatty alcohol having an HLB value strictly greater than 16, the viscosity of which increases rapidly over time once prepared.

[0030] Indeed, the handling steps no longer need to be implemented as quickly as possible once the composition has been prepared.

[0031] The composition according to the invention is therefore easily manipulated to carry out the polymerization or copolymerization of monomers with ethylenic unsaturation.

[0032] The composition according to the invention is particularly easy to pump.

[0033] The composition according to the invention has in particular the advantage of being stable for a period of at least two months at a temperature ranging from 1 to 30°C, preferably from 5 to 27°C.

[0034] Thus, the composition according to the invention can therefore be safely transported and stored in polymer production units and lead to good quality polymeric materials.

[0035] The invention also relates to the use of at least one 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.

[0036] 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. Thus, the composition according to the invention is compatible with the polymerization or copolymerization of ethylenically unsaturated monomers, preferably vinyl monomers, more preferably halogenated vinyl monomers.

[0037] Another aspect of the present invention relates to a process for preparing a polymer or a copolymer comprising one or more motifs derived from halogenated ethylenic unsaturates, comprising at least one step of polymerizing at least one halogenated ethylenic unsaturates monomer, optionally in a mixture with at least one ethylenic unsaturates comonomer, in a composition as defined above.

[0038] Other features and advantages of the invention will become clearer upon reading the description and examples that follow.

[0039] In what follows, and unless otherwise indicated, the bounds of a domain of values ​​are included within that domain.

[0040] The expression "at least one" is equivalent to the expression "one or more".

[0041] Composition

[0042] Linear Diacyl Peroxide

[0043] The linear diacyl peroxide(s) present in the composition according to the invention, preferably correspond(s) to the following formula (A):

[0044] R1-C(=O)-OOC(=O)-R2

[0045] (HAS)

[0046] Formula (A) in which:

[0047] - Ri and / or R.2, identical or different, independently represent a linear alkyl group in C6-C21, preferably in C7-C20, preferably in C9-C18, preferably in Cio-Cis, preferably in C10-C15, and more preferably in C11-C15.

[0048] Preferably, Ri and R2 are identical and represent a linear alkyl group in C6-C21, preferably in C7-C20, preferably in C9-C18, preferably in Cio-Cis, preferably in C10-C15, and more preferably in Cn-C15.

[0049] The linear diacyl peroxide(s) is / are preferentially chosen from the group consisting of diheptanoyl peroxide, dioctoyl peroxide, didecanoyl peroxide, dilauroyl peroxide, and mixtures thereof.

[0050] More preferably, linear diacyl peroxide is dilauroyl peroxide.

[0051] The linear diacyl peroxide(s) is / are present in a content ranging from 5 to 50% by weight, preferably in a content ranging from 30 to 45% by weight, relative to the total weight of the composition.

[0052] Oxyalkylated fatty alcohol having an HLB value less than or equal to 16

[0053] As previously stated, the composition according to the invention further comprises at least one oxyalkylated fatty alcohol having an HLB value less than or equal to 16.

[0054] The oxyalkylated fatty alcohol(s) having an HLB value less than or equal to 16, present in the composition according to the invention, is or are different from alkyl(Cs-C24) oxyalkylated phenol.

[0055] Preferably, the oxyalkylated fatty alcohol(s) has an HLB value less than or equal to 15, more preferably less than or equal to 14.5, again preferably less than or equal to 13, again preferably less than or equal to 12.5, even better less than or equal to 11.

[0056] Preferably, the oxyalkylated fatty alcohol(s) has an HLB value greater than or equal to 8, more preferably greater than or equal to 9.

[0057] Preferably, the oxyalkylated fatty alcohol(s) has an HLB value of 8 to 16, more preferably of 8 to 15, even more preferably of 9 to 14.5, even more preferably of 9 to 13, better of 9 to 12.5, even better of 9 to 11.

[0058] For the purposes of this invention, "HLB (or Hydrophilic Lipophilic Balance)" refers to the hydrophilic / lipophilic balance of a surfactant at 25°C, as defined by Griffin. This means the equilibrium between the size and strength of the hydrophilic group and the size and strength of the lipophilic group of the surfactant. The HLB (hydrophilic-lipophilic balance) value according to Griffin is defined in J. Soc. Cosm. Chem. 1954 (volume 5), pages 249-256. The oxyalkylated motifs are more particularly oxyethylenated motifs (i.e., ethylene oxide groups), oxypropylenated motifs (i.e., propylene oxide groups), or a combination thereof, preferably oxyethylenated or a combination of oxyethylenated and oxypropylenated motifs.

[0059] The oxyethylenated (i.e. ethylene oxide groups) and oxypropylenated (i.e. propylene oxide groups) motifs can be distributed statistically or in blocks.

[0060] The number of moles of ethylene oxide and / or propylene varies preferably from 1 to 250, preferably from 1 to 200, more preferably from 2 to 100, better from 2 to 50 and even better from 2 to 40.

[0061] More preferably, oxyalkylated motifs are oxyethylated motifs.

[0062] Preferably, the number of moles of ethylene oxide varies from 2 to 40, better from 2 to 20.

[0063] Preferably, the oxyalkylated fatty alcohol(s) is / are chosen from among the oxyethylated fatty alcohols in which the number of moles of ethylene oxide varies from 2 to 40, more preferably from 2 to 20.

[0064] Fatty alcohol, for the purposes of this invention, means an alcohol comprising at least 8 carbon atoms (excluding carbons of oxyalkylated motifs), preferably a C8-C40 alcohol, preferably a C8-C30 alcohol, more preferably a C8-C20 alcohol, better a C10-C20 alcohol.

[0065] The oxyalkylated fatty alcohol(s) correspond(s) to the following formula (B):

[0066] R3-(OCH2CH2)n-(OCH2CH2CH2)m-OH (B)

[0067] Formula (B) in which:

[0068] R3 represents a linear or branched alkyl group, particularly linear, at C8-C40, preferably at C8-C30, more preferably at C8-C20, better at C10-C20,

[0069] n is an integer ranging from 0 to 50, preferably n is an integer ranging from 1 to 40,

[0070] m is an integer ranging from 0 to 50, preferably m is an integer ranging from 0 to 40,

[0071] given that the sum n+m is at least equal to 1. Preferably, in formula (B), the sum n+m varies from 2 to 100, better from 2 to 80.

[0072] Preferably, the oxyalkylated fatty alcohol(s) correspond(s) to the following formula (B'):

[0073] R3-(OCH2CH2)n-OH (B')

[0074] Formula (B') in which:

[0075] R3 represents a linear or branched alkyl group, particularly linear, at C8-C40, preferably at Cs-C30, more preferably at C8-C20, better at C10-C20,

[0076] n is an integer ranging from 1 to 50, preferably ranging from 2 to 40, better from 2 to 20.

[0077] Preferably, in formula (B'), R3 represents a linear C8-C20 alkyl group and n is an integer ranging from 2 to 20.

[0078] Even more preferably, in formula (B'), R3 represents a linear C10-C20 alkyl group and n is an integer ranging from 2 to 20.

[0079] According to a preferred embodiment, the oxyalkylated fatty alcohol(s) according to the invention have an HLB value less than or equal to 14.5, preferably less than or equal to 13, and correspond(s) to formula (B') as defined above.

[0080] According to a preferred embodiment, the oxyalkylated fatty alcohol(s) according to the invention have an HLB value ranging from 9 to 13, better from 9 to 12.5, even better from 9 to 11, and correspond(s) to the formula (B') in which R3 represents a linear C10-C20 alkyl group, n is an integer ranging from 2 to 40, better from 2 to 20.

[0081] The oxyalkylated fatty alcohol(s) having an HLB value less than or equal to 16 is or are 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 0.5 to 5% by weight, relative to the total weight of the composition.

[0082] Preferably, the composition according to the invention comprises:

[0083] - at least one linear diacyl peroxide corresponding to formula (A) in which Ri and R2 are identical and represent a linear alkyl group in C6-C21, preferably in C7-C20, preferably in C9-C18, preferably in C10-C18, preferably in C10-C15, and more preferably in C11-C15, - at least one oxyalkylated fatty alcohol having an HLB value less than or equal to 14.5, preferably less than or equal to 13 and corresponding to formula (B), preferably to formula (B').

[0084] Advantageously, the composition according to the invention comprises:

[0085] - at least one linear diacyl peroxide corresponding to formula (A) in which Ri and R2 are identical and represent a linear alkyl group at C6-C21, preferably at C7-C20, preferably at C9-C18, preferably at C10-C18, preferably at C10-C15, and more preferably at C11-C15,

[0086] - at least one oxyalkylated fatty alcohol having an HLB value ranging from 9 to 13, preferably from 9 to 12.5, and corresponding to formula (B), preferably to formula (B').

[0087] Advantageously, the composition according to the invention comprises dilauroyl peroxide and at least one oxyalkylated fatty alcohol having an HLB value ranging from 9 to 13, better from 9 to 12.5, even better from 9 to 11, and corresponding to the formula (B') in which R3 represents a linear C10-C20 alkyl group, n is an integer ranging from 2 to 20.

[0088] Polyvinyl alcohol

[0089] The composition according to the invention may further comprise at least one polyvinyl alcohol (PVA).

[0090] Preferably, polyvinyl alcohol (PVA) is partially hydrolyzed. Advantageously, polyvinyl alcohol has a degree of hydrolysis less than or equal to 90%, preferably less than or equal to 85%, and even more preferably less than or equal to 80%.

[0091] Preferably, the degree of hydrolysis of polyvinyl alcohol (PVA) varies from 45 to 90%, more preferably from 50 to 85%, better from 55 to 80%.

[0092] Advantageously, the degree of hydrolysis of polyvinyl alcohol (PVA) varies from 70 to 75%.

[0093] Preferably, polyvinyl alcohol (PVA) is present in the composition according to the invention in a content less than or equal to 5% by weight, preferably in a content less than or equal to 3% by weight, more preferably in a content less than or equal to 1.5% by weight relative to the total weight of the composition.

[0094] Preferably, polyvinyl alcohol (PVA) is present in the composition according to the invention in a content greater than or equal to 0.05% by weight, preferably in a content greater than or equal to 0.1% by weight relative to the total weight of the composition.

[0095] Polyvinyl alcohol (PVA) may be present in the composition according to the invention in a content ranging from 0.05 to 5% by weight, preferably in a content ranging from 0.1 to 3% by weight, more preferably in a content ranging from 0.1 to 1.5% by weight.

[0096] According to a preferred embodiment, the weight ratio between the oxyalkylated fatty alcohol(s) having an HLB value less than or equal to 16, as described above, and the polyvinyl alcohol (PVA), described above, is strictly less than 1.

[0097] Preferably, the composition according to the invention comprises:

[0098] - at least one linear diacyl peroxide corresponding to formula (A) in which Ri and R2 are identical and represent a linear alkyl group in C7-C20, preferably in Cio-Cis, and more preferably in C10-C16,

[0099] - at least one oxyalkylated fatty alcohol having an HLB value less than or equal to 14.5, preferably less than or equal to 13 and conforming to formula (B), preferably to formula (B'),

[0100] - at least one polyvinyl alcohol (PVA) having a degree of hydrolysis ranging from 50 to 85%, better from 55 to 80%, even more preferably from 70% to 75%.

[0101] Advantageously, the composition according to the invention comprises:

[0102] - at least one linear diacyl peroxide corresponding to formula (A) in which Ri and R2 are identical and represent a linear alkyl group in C10-C16,

[0103] - at least one oxyalkylated fatty alcohol having an HLB value ranging from 9 to 13, better from 9 to 12.5, even better from 9 to 11, and corresponding to formula (B') in which R3 represents a linear C10-C20 alkyl group, n is an integer ranging from 2 to 20,

[0104] - at least one polyvinyl alcohol (PVA) having a degree of hydrolysis ranging from 50 to 85%, better from 55 to 80%, even more preferably from 70 to 75%.

[0105] Water

[0106] The composition according to the invention comprises water, preferably in a content of 50 to 95% by weight, more preferably in a content of 70 to 55% by weight, relative to the total weight of the composition.

[0107] Preferably, the water is deionized or distilled. Additives

[0108] The composition according to the invention may also include one or more additives intended to provide the final composition with particular properties / characteristics, for example, antifreeze properties. These additives will ideally be present for the final polymerization or copolymerization.

[0109] The additive may be chosen from the group consisting of antifreeze agents, 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; fillers such as calcium carbonate and 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; colorants; plasticizers; fluidizers and flame retardant additives such as aluminium or magnesium hydroxides.

[0110] The composition according to the invention may optionally contain one or more additives including pH adjusting agents such as phosphate and citrate buffers, chelating agents, biocides for example fungicides, antiozonants, antioxidants, antidegradants, swelling agents and release agents.

[0111] These additives can be added in the quantities usually used and known to those skilled in the art. These additives are generally used at concentrations between 10 ppm and 10,000 ppm by weight relative to the final polymer weight. Plasticizers, flow agents, and flame retardants can be used at concentrations well above 10,000 ppm.

[0112] Preparation of the composition

[0113] The present invention also relates to a method for preparing a composition according to the invention, said method comprising a step a) of mixing:

[0114] of at least one oxyalkylated fatty alcohol having an HLB value less than or equal to 16, as described above, of water, of one or more linear diacyl peroxides, as defined above

[0115] and possibly at least polyvinyl alcohol, as described previously.

[0116] In a preferred embodiment, the oxyalkylated fatty alcohol and water are pre-mixed, preferably with regular stirring, to obtain an aqueous phase. In other words, in this preferred embodiment, the process includes a step a'), prior to step a) of mixing the oxyalkylated fatty alcohol and water.

[0117] Preferably, the said linear diacyl peroxide(s), as defined above, is or are added to said aqueous phase.

[0118] Preferably, the process according to the invention includes a step b) of grinding the organic peroxide(s) as described above.

[0119] Said step b) may be prior to, simultaneous with or subsequent to step a), preferably simultaneous.

[0120] Preferably, the grinding step b) is carried out using a conventional grinding or high shear dispersion device, such as Ultra Turrax® type colloid mills, bead mills, ball mills, dispax mills, ultrasonic mills.

[0121] The steps mentioned above may be carried out in the specific order prescribed or in a different order. Apart from the specific successive steps of the process for preparing the composition according to the invention, the preparation of the suspension is indistinguishable from the techniques and apparatus well known to those skilled in the art.

[0122] Alternatively to step b), the process according to the invention may include a step b') of heating the composition obtained in step a). Preferably, the heating step b) is carried out at a temperature between:

[0123] -the melting point of said linear diacyl peroxide, as defined above, or, where several linear diacyl peroxides are present, at a temperature equal to or greater than the highest melting point of said linear diacyl peroxides: and

[0124] -the self-accelerating decomposition temperature of said linear diacyl peroxide, as defined above, or, when several linear diacyl peroxides are present, a temperature lower than the lowest decomposition temperature of said linear diacyl peroxides. The melting temperature can be determined by differential scanning calorimetry (DSC) with a heating rate of 10°C / min. The melting temperature then corresponds to the peak of the endothermic melting peak obtained during the measurement.

[0125] The self-accelerating decomposition temperature (SADT) is the lowest temperature at which an uncontrolled reaction occurs, i.e., self-accelerating decomposition within its packaging. In other words, the self-accelerating decomposition temperature represents the temperature at which the chemical process leading to uncontrolled decomposition, possibly accompanied by spontaneous combustion and explosion, begins.

[0126] Furthermore, deionized or distilled water is typically used to prepare the compositions. Preferably, the water content ranges from 50 to 95% by weight, and more preferably from 70 to 55% by weight, relative to the total weight of the composition.

[0127] According to one embodiment feature, the process according to the invention is characterized in that an ultrasonic mixer or a rotor-stator mixer is used.

[0128] Use

[0129] The present invention also relates to the use of at least one 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.

[0130] Preferably, the ethylenically unsaturated monomers are chosen from the group consisting of vinyl halide monomers (i.e. halogenated vinyl monomers), and more preferably vinyl chloride.

[0131] Process for preparing the polymer or copolymer

[0132] Similarly, another object of the present invention relates to a process for preparing a polymer or a copolymer comprising one or more motifs derived from halogenated ethylenic unsaturation monomers, comprising at least one step of polymerizing at least one halogenated ethylenic unsaturation monomer, optionally in a mixture with at least one ethylenic unsaturation comonomer, in a composition as defined above.

[0133] According to one embodiment, the process includes at least one mixing step of at least one halogenated ethylenic unsaturation monomer, optionally with at least one ethylenic unsaturation comonomer, and of the composition as defined above, before the polymerization step.

[0134] The polymerization step preferably occurs at a temperature ranging from 45°C to 80°C, more preferably ranging from 60 to 75°C.

[0135] Preferably, the halogenated ethylenically unsaturated monomer(s) is or are chosen from the group consisting of vinyl halide monomers (i.e. halogenated vinyl monomers), and more preferably vinyl chloride.

[0136] The co-monomer(s) with ethylenic unsaturation is / are different from the halogenated monomer(s) with ethylenic unsaturation.

[0137] The co-monomer(s) with ethylenic unsaturation can be chosen from the group consisting of acrylates, vinyl esters, vinyl ethers, butadiene, aromatic vinyl compounds such as styrene.

[0138] Preferably, the process according to the invention is a process for preparing a polymer comprising one or more motifs derived from halogenated ethylenic unsaturated monomers, preferably derived from vinyl halide monomers, comprising at least one polymerization step of at least one halogenated ethylenic unsaturated monomer, preferably at least one vinyl halide monomer, in a composition as defined above.

[0139] Advantageously, the process according to the invention is a process for preparing a polymer comprising one or more motifs derived from vinyl chloride, comprising at least one step of polymerizing vinyl chloride in a composition as defined above.

[0140] The following examples serve to illustrate the invention but are not intended to be limiting. EXAMPLES

[0141] Example 1

[0142] The following compositions A1 and B were prepared from the ingredients listed in Table 1 below:

[0143] [Table 1]

[0144]

[0145] Preparation protocol for compositions Al and B

[0146] Compositions Al and B were prepared according to the same operating protocol.

[0147] In a beaker, pour the demineralized water followed by the polyvinyl alcohol diluted to 8.30% in water, as well as the suspending agent (namely the oxyethylenated fatty alcohol having an HLB value of 9.7 for composition Al and the oxyethylenated fatty alcohol having an HLB value of 16.7 for composition B).

[0148] The ingredients are added while stirring regularly, at approximately 600 rpm, using a standard three-pronged blade at its lower end. From the moment the last ingredient of the aqueous phase is added, homogenization takes five minutes.

[0149] Powdered dilauroyl peroxide is ground in the stainless steel chamber of an IKA A10 mill, pre-cooled with ice, until a particle size of d(50) of 4.5 µm is obtained. This dilauroyl peroxide is then added at regular intervals to the aqueous phase while stirring. Once all the dilauroyl peroxide has been incorporated into the aqueous phase, the mixture is blended with an Ultra-Turrax® agitator-disperser at a speed ranging from 1500 rpm to 9000 rpm.

[0150] This yields aqueous suspensions of dilauroyl peroxide.

[0151] Tests performed:

[0152] In this example, the dynamic viscosities of the Al and B compositions were measured using a "Viscotester Haake VT550" type viscometer.

[0153] The measuring device is the "SV-DIN 53019", referring to the DIN 53019 standard. The measurement is performed using coaxial cylinders that create shear. Between 5 and 10 ml (milliliters) of the composition is introduced into the measuring chamber.

[0154] Dynamic viscosity measurements are performed at room temperature after preparation of the composition (T0) and after two months (T0 + 2 months) at different shear rates, namely at shear rates of 125.5 s' 1 , of 245 s' 1 , of 349 s' 1 and 583 s' 1 .

[0155] The results are summarized in Table 2 below:

[0156] [Table 2]

[0157]

[0158] The results show that the composition according to the invention (Al) exhibits a lower viscosity, whether after production (T0) or after a storage period of two months at room temperature (T0 + 2 months), than those measured for a comparative composition (B) having an HLB value strictly greater than 16, at a shear rate greater than 100 s' 1 More specifically, the viscosity of composition (Al) varies by less than 15% of its initial viscosity, while over the same period, the viscosity of composition (B) varies by nearly 70% of its initial viscosity.

[0159] Example 2

[0160] The following compositions A2 and A3 were prepared from the ingredients listed in Table 3 below:

[0161] [Table 3]

[0162]

[0163] Compositions A2 and A3 were prepared according to the operating protocol described previously.

[0164] Tests performed:

[0165] In this example, the dynamic viscosities of compositions A2 and A3 were measured using a "Viscotester Haake VT550" type viscometer in accordance with example 1.

[0166] The results are grouped in Table 4 below: [Table 4]

[0167]

[0168] The results show that the compositions according to the invention (A2) and (A3) exhibit low viscosity, whether after production (TO) or after a storage period of two months at room temperature (TO + 2 months).

Claims

DEMANDS 1. Composition in the form of an aqueous suspension comprising at least one linear diacyl peroxide and at least one oxyalkylated fatty alcohol having an HLB value less than or equal to 16.

2. Composition according to the preceding claim, characterized in that the linear diacyl peroxide(s) correspond(s) to the following formula (A): R1-C(=O)-OOC(=O)-R2 (HAS) Formula (A) in which: Ri and / or R.2, identical or different, independently represent a linear alkyl group in C6-C21, preferably in C7-C20, preferably in C9-Ci8, preferably in Cio-Cis, preferably in C10-C15, and more preferably in C11-C15.

3. Composition according to claim 1 or 2, characterized in that the linear diacyl peroxide(s) is or are selected from the group consisting of diheptanoyl peroxide, dioctoyl peroxide, didecanoyl peroxide, dilauroyl peroxide, and mixtures thereof, preferably dilauroyl peroxide.

4. Composition according to any one of the preceding claims, characterized in that the linear diacyl peroxide is dilauroyl peroxide.

5. Composition according to any one of the preceding claims, characterized in that the oxyalkylated fatty alcohol(s) has an HLB value less than or equal to 15, more preferably less than or equal to 14.5, even more preferably less than or equal to 13, even more preferably less than or equal to 12.5, even better less than or equal to 11.

6. Composition according to any one of the preceding claims, characterized in that the oxyalkylated fatty alcohol(s) has an HLB value greater than or equal to 8, more preferably greater than or equal to 9.

7. Composition according to any one of the preceding claims, characterized in that the oxyalkylated fatty alcohol(s) correspond(s) to the following formula (B): R3-(OCH2CH2)n-(OCH2CH2CH2)m-OH (B)Formula (B) in which: R3 represents a linear or branched alkyl group, particularly linear, at C8-C40, at C8-C40, preferably at C8-C30, more preferably at C8-C20, better at C10-C20, n is an integer ranging from 0 to 50, preferably n is an integer ranging from 1 to 40, m is an integer ranging from 0 to 50, preferably m is an integer ranging from 0 to 40, given that the sum n+m is at least equal to 1.

8. Composition according to any one of the preceding claims, characterized in that the oxyalkylated fatty alcohol(s) correspond(s) to the following formula (B'): R3-(OCH2CH2)n-OH (B') Formula (B') in which: R3 represents a linear or branched alkyl group, particularly linear, at C8-C40, preferably at C8-C30, more preferably at C8-C20, better at C10-C20, n is an integer ranging from 1 to 50, preferably ranging from 2 to 40, better from 2 to 20.

9. Composition according to any one of the preceding claims, characterized in that the HLB value of the oxyalkylated fatty alcohol(s) varies from 9 to 13, better from 9 to 12.5, even better from 9 to 11.

10. Composition according to any one of the preceding claims, characterized in that the oxyalkylated fatty alcohol(s) having an HLB value less than or equal to 16 is or are 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, relative to the total weight of the composition.

11. Composition according to any one of the preceding claims, characterized in that it further comprises at least one polyvinyl alcohol (PVA), preferably partially hydrolyzed.

12. Composition according to the preceding claim, characterized in that the degree of hydrolysis of the polyvinyl alcohol (PVA) varies from 45 to 90%, more preferably from 50 to 85%, better from 55 to 80%.

13. Composition according to any one of claims 11 or 12, characterized in that polyvinyl alcohol (PVA) is present in a content less than or equal to 5% by weight, preferably in a content less than or equal to 3% by weight, more preferably in a content less than or equal to 1.5% by weight relative to the total weight of the composition.

14. Use of at least one composition as defined according to any one of claims 1 to 13 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.

15. A process for preparing a polymer or copolymer comprising one or more motifs derived from halogenated ethylenic unsaturates, comprising at least one step of polymerizing at least one halogenated ethylenic unsaturates monomer, optionally in a mixture with at least one ethylenic unsaturates comonomer, in a composition as defined according to any one of claims 1 to 13.

16. A process according to claim 15, characterized in that the halogenated ethylenically unsaturated monomer(s) is or are selected from the group consisting of vinyl halide monomers, more preferably vinyl chloride.

17. A process according to claim 15 or 16, characterized in that the ethylenically unsaturated co-monomer(s) is or are selected from the group consisting of acrylates, vinyl esters, vinyl ethers, butadiene and aromatic vinyl compounds such as styrene.

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