FR3101349A1 - Solid anhydrous composition in powder form comprising at least one organic peroxide, at least one phlegmatizing agent and at least one binder and corresponding preparation process - Google Patents

Abstract

Solid anhydrous composition in powder form comprising at least one organic peroxide, at least one phlegmatizing agent and at least one binder and corresponding preparation process The present invention relates to a composition comprising at least one solid organic peroxide, at least one solid phlegmatizing agent, of preferably having a melting point greater than or equal to 40 ° C, and at least one solid binder having an enthalpy of fusion greater than or equal to 125 kJ / kg. The invention also relates to the use of the composition as defined above as a polymerization initiator for the manufacture of acrylic resins and polyester resins, preferably acrylic resins or as a polymer modifier. The present invention also relates to a process for preparing such a composition. Reference: no figure

Description

Solid anhydrous composition in powder form comprising at least one organic peroxide, at least one phlegmatizing agent and at least one binder and corresponding method of preparation

The present invention relates to a composition comprising at least one solid organic peroxide, at least one solid phlegmatizing agent preferably having a melting point greater than or equal to 40°C and at least one solid binder having an enthalpy greater than or equal to 125 kJ/ kg (kiloJoules/moles).

The invention also relates to the use of the composition as defined above as an initiator for the polymerization of acrylic resins and unsaturated polyester resins, preferably acrylic resins, or as a polymer modifier, for example in as a crosslinking agent, grafting agent or rheology modifier.

The present invention also relates to a process for the preparation of such a composition.

Acrylic resins and polyester resins are currently commonly used in many varied technical fields for industrial or decorative applications, for example in the production of paints, in particular intended for road marking, the protection of structures and the waterproofing of floors, the production of chemical seals (also called chemical anchors) in order to fix objects of varying sizes on various surfaces, the production of composite materials in association with reinforced fibers, the manufacture of marbles, natural or synthetic, as well as mastics used in particular for the repair of bodywork.

Acrylic resins are usually appreciated by users for their speed of setting, including at low temperatures of the order of 10°C, their strong adhesion to different types of substrates as well as their high mechanical resistance, while polyester resins offer very good chemical resistance, especially in an acid environment, good properties in terms of mechanical resistance and rapid commissioning.

Such resins also have the advantage of being able to be applied manually or by spraying, in particular by implementing different spraying techniques, on different types of surfaces.

Acrylic resins and polyester resins are generally implemented by polymerization, in particular by radical route from one or more acrylic monomers, identical or different, in the presence of organic peroxides, in liquid or solid form, playing the role of polymerization initiators.

However, organic peroxides most often constitute highly unstable species when heated because they decompose relatively easily under the action of a low heat input. Thus, in the event of an uncontrolled rise in their storage temperature, certain organic peroxides may undergo self-accelerating exothermic decomposition leading to fires and/or violent explosions. In addition, under these conditions, some of these organic peroxides in particular release combustible vapors liable to react with any source of ignition, which can significantly increase, or even accelerate, the risk of a violent explosion.

Such organic peroxides thus have a self-accelerating decomposition temperature T _DAA (also called Self Accelerating Decomposition Temperature in English and denoted SADT) which corresponds to the lowest temperature at which an uncontrolled reaction occurs, ie a self-accelerating decomposition in its packaging. In other words, the self-accelerating decomposition temperature T _DAA represents the temperature at which the chemical process leading to uncontrolled decomposition, possibly accompanied by self-combustion and explosion phenomena, begins.

Such risky behavior is therefore incompatible with the rules in force regarding the transport and storage of hazardous materials. In particular, it is important to take adequate precautionary measures during the storage and handling of such organic peroxides, in particular by making sure to remain at temperatures below their self-accelerating decomposition temperature T _DAA to minimize the risks of fire and/or uncontrolled decomposition. Thus in some cases, such precautionary measures involve maintaining the organic peroxides at a storage temperature which is preferably at least 10° C. lower, more preferably at least 20° C. lower than the self-accelerating decomposition temperature T _DAA .

In order to overcome these various drawbacks, organic peroxides can be diluted or mixed with inert products, i.e. non-reactive in contact with organic peroxide, called phlegmatizing agents. Several possibilities exist: solubilization in a liquid phlegmatizer, mixing with an inert solid phlegmatizer, or even being implemented in the form of an emulsion in the liquid phlegmatizer. In particular, phlegmatizing agents make it possible to limit the effects during the uncontrolled decomposition of organic peroxides and to reduce, consequently, the various risks associated with their handling.

By way of example, solid anhydrous compositions have been proposed which are in the form of particles comprising in particular at least one solid organic peroxide and benzoic acid, substituted or not, as a phlegmatizing agent.

However, the compositions thus obtained have the disadvantage of being inhomogeneous, in particular at the level of the distribution of the particle size. Indeed, on the one hand, the majority of the particles within the composition have a size that is too small, i.e. less than 100 micrometers, which makes them too fine and difficult to use subsequently in the manufacture of resins, in particular resins acrylics and polyester resins. On the other hand, a significant quantity of the particles has too large a size, i.e. greater than or equal to 500 micrometers, which increases the dissolution time of the composition during its use during the implementation of a process of synthesis of acrylic resins and polyester resins. In other words, the yield of particles rich in organic peroxide likely to be able to be effectively used during a process for the synthesis of acrylic resins or polyester resins still remains too low.

In order to reduce the quantity of fine particles and obtain a more homogeneous composition in terms of particle size distribution, it has already been proposed to add a mineral oil during the preparation.

Nevertheless, the presence of a mineral oil within the solid anhydrous composition based on solid organic peroxide can create problems in the final application, in particular the mineral oil tends to migrate to the surface of the acrylic paint after polymerization . Also, the presence of mineral oil in the solid peroxide formulation reduces its flow properties, making it more susceptible to the problem of caking during transportation and storage.

Thus one of the objectives of the present invention is in particular to propose a composition based on stable and homogeneous organic peroxide, intended in particular to be used as polymerization initiators in the manufacture of acrylic resins and polyester resins, which does not does not have the aforementioned drawbacks.

In other words, there is a real need to prepare a stable and homogeneous organic peroxide-based composition which is compatible with acrylic resins and polyester resins intended to be synthesized.

The present invention therefore relates in particular to a composition comprising:

• at least one solid organic peroxide,
• at least one solid phlegmatizing agent, preferably having a melting point greater than or equal to 40°C, and
• at least one solid binder having an enthalpy of fusion greater than or equal to 125 kJ/kg, preferably ranging from 145 kJ/kg to 250 kJ/kg.

The composition as defined thus represents an organic peroxide composition in powder form which has the desired average particle size as well as a homogeneous particle size distribution while remaining stable, whether on storage or during handling.

In particular, the particle size distribution of the composition according to the invention is narrower compared to that of a conventional composition in the form of organic peroxide powder phlegmatized with benzoic acid.

In addition, the particle size distribution of the composition according to the invention is advantageously more narrow when the composition comprises at least one mineral filler, preferably a silica.

The composition according to the invention can thus be effectively used subsequently as polymerization initiators in the synthesis of acrylic resins and unsaturated polyester resins, preferably in the synthesis of acrylic resins.

A subject of the invention is also the use of the composition as defined above as an initiator for the polymerization of acrylic resins and unsaturated polyester resins, preferably acrylic resins, or as a polymer modifier, for example as as polymer crosslinking agent, grafting agent, or rheology modifier, in particular as polymerization initiator of acrylic resins and unsaturated polyester resins.

Indeed, the composition according to the invention proves to be compatible with the acrylic resins and the polyester resins obtained, preferably with the acrylic monomers, which minimizes the risks of salting out mineral oils when obtaining such resins, in especially when obtaining an acrylic paint.

In addition, the present invention also relates to a method for preparing a composition comprising a step of adding a binder in the molten state, endowed with an enthalpy of fusion greater than or equal to 125 kJ/kg, preferably ranging from 145 kJ/kg to 250 kJ/kg in a mixture comprising a solid organic peroxide as defined above and at least one phlegmatizing agent as defined above.

The process according to the invention has the advantage of being able to lead mainly to an anhydrous composition, in solid form, rich in organic peroxide having a particle size greater than or equal to 100 micrometers and less than 500 micrometers.

The process according to the invention makes it possible to dispense with a step of heating the organic peroxide and thus to minimize the risks of exothermic decomposition during the preparation of the composition. In other words, the method according to the invention ensures good security during its implementation.

In addition, the method according to the invention is easy to implement and consumes a small amount of energy.

The present invention also relates to a composition capable of being obtained by the process described above.

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

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

The phrase "at least one" is equivalent to the phrase "one or more".

Composition

The composition according to the invention comprises at least one solid organic peroxide, at least one solid phlegmatizing agent having a melting point higher than the self-accelerating decomposition temperature of the organic peroxide and at least one solid binder, endowed with an enthalpy of melting greater than or equal to 125 kJ/kg, preferably ranging from 145 kJ/kg to 250 kJ/kg.

Preferably, the composition is a solid composition.

Preferably, the composition herein is in powder form.

By "solid organic peroxide", "solid phlegmatizing agent", and "solid binder", it is meant within the meaning of the present invention that the compound is in the solid state at room temperature and under atmospheric pressure (approximately 1 bar).

By "ambient temperature" is meant within the meaning of the present invention a temperature ranging from 15°C to 27°C, preferably ranging from 20°C to 25°C.

Preferably, the storage temperature is 10° C. lower, more preferably 20° C. lower, relative to the self-accelerated decomposition temperature of the organic peroxide.

Preferably, the organic peroxide has a melting point greater than or equal to 30°C.

The melting temperature is determined by differential calorimetric analysis (DSC) with a temperature rise rate of 10° C./min. The melting temperature then corresponds to the peak of the endothermic melting peak obtained during the measurement.

Preferably, the solid organic peroxide is chosen from the group consisting of solid diacyl peroxides, solid peroxydicarbonates, solid ketone peroxides, solid peroxy esters, solid hydroperoxides, solid dialkyl peroxides and mixtures thereof.

The solid diacyl peroxides are preferably chosen from the group consisting of dibenzoyl peroxide, di(2-methylbenzoyl) peroxide, di(methoxybenzoyl) peroxide, di(2-methoxycarbonylbenzoyl) peroxide, di (2-benzylbenzoyl), di (2-benzylbenzoyl) peroxide, di (4-fluorobenzoyl) peroxide, di (3-chlorobenzoyl) peroxide, di (4-chlorobenzoyl) peroxide, di ( 2,4-dichlorobenzoyl), dibenzoyl diperoxy adipate, benzoyl octadecanoyl peroxide, dilauroyl peroxide, dihexadecanoyl peroxide, di(chloroacetyl) peroxide, and di(3-carboxypropionyl) peroxide.

The solid peroxydicarbonates are preferably dialkyl peroxydicarbonates, chosen in particular from the group consisting of dibenzyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, di(cis-3,3,5-trimethylcyclohexyl) peroxydicarbonate, di(4 -t-butylcyclohexyl), dibornyl peroxydicarbonate, di(2-phenoxyethyl) peroxydicarbonate, di-n-tridecyl peroxydicarbonate and di-n-hexadecyl peroxydicarbonate.

The solid ketone peroxides are preferably chosen from the group consisting of di(1-hydroxycyclohexyl) peroxide, 1-hydroxycyclohexyl-1-hydroperoxycyclohexyl, di(hydroperoxycyclohexyl) peroxide and 3,5-dihydroxy-3,5 -dimethyl-1,2-dioxolane.

The solid peroxyesters are preferably chosen from the group consisting of di-t-butyl diperoxyterephthalate, di-t-butyl diperoxysuccinate, di-t-butyl-diperoxyadipate, di-t-butyl diperoxyphthalate, peroxy - (t-Butyl 3-carboxypropionate), t-butylperoxy-(3-carboxy-2-propenoate) and 2,5-dimethyl-2,5-di (benzoylperoxy) hexane.

The solid alkyl hydroperoxides are preferably selected from the group consisting of 2,5-dimethyl-2,5-dihydroxyperoxyhexane (mp, 104°C-5°C), 2,5-dimethyl-2,5- dihydroxypoxy-3-hexyne, 2,7-dimethyl-2,7-dihydroperoxy-3,5-octadiyne, 1,4-di (1-methyl-1-hydroxyperoxyethyl) benzene and 1,3,5, - tri (1-methyl-1-hydroperoxyethyl) benzene.

The solid dialkyl peroxides are preferably chosen from the group consisting of di-cumyl peroxide, 1,4-di[1-methyl-1-(tertio-butylperoxy)ethyl]benzene, 1,3-di- [1-methyl-1-(tertio-butylperoxy)-ethyl]-benzene and di(isopropyl-cumyl) peroxide.

Preferably, the solid organic peroxide is chosen from the group consisting of solid diacyl peroxides, solid peroxydicarbonates and mixtures thereof. Even more preferentially, the solid organic peroxide is chosen from the group consisting of solid diacyl peroxides.

Preferably, the organic peroxide is dibenzoyl peroxide such as that sold under the trade name Luperox® A75 by the company Arkema.

The solid organic peroxide is preferably present in a content ranging from 10 to 80% by weight, preferably in a content ranging from 15% to 75% by weight, and more preferably in a content ranging from 20 to 60% by weight per relative to the total weight of the composition according to the invention.

Within the meaning of the present invention, the organic peroxide content is expressed relative to pure organic peroxide, that is to say without phlegmatizer.

Preferably, the solid phlegmatizing agent has a melting temperature above the self-accelerating decomposition temperature of the organic peroxide. Preferably, the phlegmatizing agent has a melting point greater than or equal to 40°C.

The melting point of the phlegmatizing agent is determined by differential scanning calorimetry (DSC) with a temperature rise rate of 10°C/min. The melting temperature then corresponds to the peak of the endothermic melting peak obtained during the measurement.

Preferably, the phlegmatizing agent has an enthalpy less than or equal to the enthalpy of fusion of the solid binder, preferably is less than 125 kJ/kg.

The enthalpy of fusion is determined by differential calorimetric analysis (DSC) with a temperature rise rate of 10°C/min., using for example the ISO 11357-3 standard.

The phlegmatizing agent is preferably chosen from the group consisting of saturated carboxylic acids having at least 11, preferably at least 12 carbon atoms, linear or branched, substituted or unsubstituted, carboxylic acids comprising at least one aromatic ring, substituted or not and mixtures thereof, preferably carboxylic acids comprising at least one aromatic ring.

Preferably, the phlegmatizing agent is chosen from the group consisting of carboxylic acids comprising at least one aromatic ring. More preferably, the phlegmatizing agent is a benzoic acid optionally substituted by one or more alkyl groups, in particular C ₁ -C ₁₀ .

Preferably, the phlegmatizing agent is chosen from benzoic acid, monomethylbenzoic acids, dimethylbenzoic acids, trimethylbenzoic acids, monoethylbenzoic acids, mono-n-propylbenzoic acids, pentamethylbenzoic acids, monoisopropylbenzoic acids, acid 4 -tert-butylbenzoic acid, phthalic acid esters such as dicyclohexyl phthalate, diphenyl phthalate, phenyl benzoate, p-tert-butyl-phenyl benzoate, alpha or beta-naphthyl benzoate, ethylene glycol dibenzoate, triethylene glycol dibenzoate or trimethylene glycol dibenzoate and 1,6-hexane-diol dibenzoate, esters thereof and mixtures thereof.

More preferably, the phlegmatizing agent is benzoic acid.

The phlegmatizing agent is preferably present in a content ranging from 19 to 89% by weight and preferably in a content ranging from 20% to 75% by weight relative to the total weight of the composition according to the invention.

Preferably, the binder is also in the solid state at the storage temperature of the solid organic peroxide.

By "storage temperature of the organic peroxide", it is meant within the meaning of the present invention the temperature at which the organic peroxide is chemically stable when stored for an extended period of time, typically at least 6 months, without suffering any damage. significant losses of peroxide content or changes in its physical form (caking, sedimentation, exudation). The storage temperature of the organic peroxide is thus lower than the self-accelerating decomposition temperature of said organic peroxide.

The solid binder has an enthalpy of fusion greater than or equal to 125 kJ/kg, preferably ranging from 145 kJ/kg to 250 kJ/kg so that it does not crystallize too quickly during the preparation of the composition according to the invention.

Preferably, the solid binder has a melting temperature above the storage temperature of the solid organic peroxide.

Preferably, the solid binder has a melting point below 90°C, more preferably still below 80°C.

Preferably, the solid binder has a melting point lower than the self-accelerating decomposition temperature T _DAA of the organic peroxide, preferably lower by at least 10°C, more preferably lower by at least 20°C.

By “self-accelerated decomposition temperature T _DAA of the organic peroxide”, is meant within the meaning of the present invention the lowest temperature at which an exothermic decomposition of the organic peroxide begins in its packaging, preferably according to the UN H.4 test. .

Preferably, when the organic peroxide is a diacyl peroxide, preferably benzoyl peroxide, the solid binder has a melting point ranging from 30°C to 80°C, in particular ranging from 35 to 60°C.

Preferably, the solid binder is chosen from the group consisting of solid fatty acids, solid fatty acid esters, solid waxes and mixtures thereof, preferably solid fatty acids.

The fatty acids are preferably linear or branched, and include in their structure a number of carbon atoms ranging from 6 to 18.

Preferably, the fatty acids are chosen from the group consisting of lauric acid, myristic acid, capric acid, palmitic acid, stearic acid and mixtures thereof. Even more preferably, the fatty acid is lauric acid.

The fatty acids are preferably different from the acids mentioned above with regard to the phlegmatizing agent.

The fatty acid esters are in particular esters comprising at least 10 carbon atoms in their structure, and preferably esters of a carboxylic acid comprising at least 10 carbon atoms and of a monoalcohol or of a polyol. The fatty acid esters according to the invention can be mono-, di- or triesters.

Preferably, the fatty acid esters are selected from the group consisting of cetyl myristate, myristyl myristate, palmityl palmitate, stearyl palmitate, palmityl stearate, stearyl stearate and mixtures thereof.

By "wax" is meant, within the meaning of the present invention, a lipophilic compound, solid, at room temperature, with a reversible solid/liquid state change and exhibiting an anisotropic crystalline organization in the solid state.

As waxes that can be used in the present invention, mention may be made of waxes of animal origin such as beeswax, spermaceti, lanolin wax and lanolin derivatives; vegetable waxes such as carnauba, candelilla, ouricury or japan wax, cocoa butter or cork fiber or sugar cane waxes; mineral waxes, for example paraffin, petrolatum, lignite or microcrystalline waxes, ozokerite, olive wax, rice wax, hydrogenated jojoba wax or absolute flower waxes such as essential wax blackcurrant flower sold by the BERTIN Company (France), animal waxes such as beeswax, or modified beeswax (cerabellina); other waxes or waxy raw materials that can be used according to the invention are in particular marine waxes such as that sold by the company SOPHIM under the reference M82, and mixtures thereof. As organic waxes, mention may also be made of waxes comprising amide functions and in particular natural or synthetic ceramides.

Preferably, the solid binder is chosen from the group consisting of solid fatty acids, preferably linear fatty acids having a number of carbon atoms ranging from 6 to 18.

Preferably, the solid binder is lauric acid.

The solid binder is preferably present in a content ranging from 1 to 40% by weight and more preferably in a content ranging from 2% to 15% by weight relative to the total weight of the composition according to the invention.

Preferably, the binder and the phlegmatizing agent of the composition according to the invention are different.

Preferably, the composition according to the present invention comprises:

• from 10 to 80% by weight, preferably from 15% to 75% by weight, and more preferably from 20 to 60% by weight of said at least one organic peroxide;
• from 19 to 89% by weight, preferably from 20% to 75% by weight of said at least one phlegmatizing agent; And
• from 1 to 40% by weight, preferably from 2% to 15% by weight of said at least one binder

relative to the total weight of the composition.

The composition according to the invention may also comprise at least one anti-caking agent and/or one dust suppressing agent.

The anti-caking agent is preferably chosen from the group consisting of calcium carbonate, talc, kaolin, silicon dioxide, fatty acid amides, fatty amines, silicone oil and metallic soaps.

The anti-caking agent is preferably present in a content ranging from 0.001 to 10% by weight, preferably in a content ranging from 0.1 to 5% by weight, relative to the total weight of the composition.

The composition can also comprise at least one mineral filler, preferably a silica.

As examples of silica that can be used in the context of the present invention, mention will be made of the silicas sold by the company Evonik under the trade names SIPERNAT®.

Mention may also be made of the silicas sold by Rhodia under the Tixosil® range.

Preferably, the silicas are hydrophobic silicas.

Hydrophobic silicas are generally obtained from a surface treatment of a silica, in particular by transforming all or almost all of the hydrophilic silanol groups into hydrophobic groups, for example by the action on the silica of halogenated silanes, alkoxylated silanes or silazanes or else by dehydration of the silica at high temperature.

As hydrophobic silica, mention may in particular be made of the silicas sold under the trade name AEROSIL®, in particular AEROSIL® R972.

The mineral filler is preferably present in a content ranging from 0.01 to 10% by weight, preferably in a content ranging from 0.1 to 5% by weight, relative to the total weight of the composition.

Advantageously, the composition is free of paraffinic oil. In particular, the composition does not include mineral oil.

Preferably, the composition according to the invention is in the form of solid particles.

Preferably, the composition according to the invention also comprises at least one dispersing agent.

Preferably, the dispersing agent is chosen from the group consisting of sodium, potassium or ammonium polyphosphates, naphthalene sulphonic acid salts and mixtures thereof, even more preferably sodium, potassium or ammonium polyphosphates, in particular those sold under the trade name Coadis® OP10.

Preferably, at least 50%, preferably at least 60%, more preferably 70%, more preferably 80% and particularly preferably 90%, by weight of the particles have a size greater than or equal to 100 micrometers and less than 500 micrometers . In other words, according to the invention, at least 50% by weight of the composition has a size greater than or equal to 100 micrometers and strictly less than 500 micrometers (the value of 500 micrometers is therefore excluded).

According to an advantageous embodiment, the composition according to the invention comprises at least one mineral filler, preferably chosen from the group consisting of silicas, more preferably hydrophobic silicas, and at least 90% by weight of the particles of the composition have a size greater than or equal to 100 micrometers and less than 500 micrometers.

The particle size of the composition can be measured using various measurement techniques, including light scattering techniques (dynamic and static), sedimentation rate measurements and microscopy. Preferably, the particle size of the composition according to the invention are measured by dry sieving, which consists in measuring the weight of material which passes through the calibrated meshes of a sieve cloth. The sieves are superimposed by decreasing mesh and the weight of material retained on each sieve is measured. This operation can be carried out by vibrating the entire sieve column using a VE 1000 sieve shaker from RETSCH, operating for 20 minutes at an oscillation angle of 1.5 mm.

Preferably, the composition according to the invention is anhydrous.

By "anhydrous" is meant within the meaning of the present invention that the composition is substantially free of water, that is to say having a water content less than or equal to 2% by weight, preferably less than or equal to 1 % by weight, relative to the total weight of the composition. Preferably, the composition does not include water.

Advantageously, according to one embodiment, the composition comprises:

• at least one solid organic peroxide chosen from the group consisting of solid diacyl peroxides, solid peroxydicarbonates and mixtures thereof, preferably solid diacyl peroxides,
• at least one solid phlegmatizing agent chosen from the group consisting of carboxylic acids comprising at least one aromatic ring, preferably unsubstituted benzoic acid,
• at least one solid binder at room temperature chosen from the group consisting of solid fatty acids.

According to this embodiment, the diacyl peroxide is preferably dibenzoyl peroxide.

In accordance with this embodiment, the composition preferably also comprises at least one mineral filler, preferably chosen from the group consisting of silicas, more preferably hydrophobic silicas.

In accordance with this embodiment, at least 50% by weight of the particles, preferably at least 80% by weight of the particles, of the composition preferably have a size greater than or equal to 100 micrometers and less than 500 micrometers.

In accordance with this embodiment, the composition preferably comprises at least one mineral filler chosen from the group consisting of silicas, more preferably hydrophobic silicas and at least 90% by weight of the particles of the composition have a size greater than or equal to 100 micrometers and less than 500 micrometers.

Use

The invention also relates to the use of the composition as defined above as an initiator for the polymerization of acrylic resins or unsaturated polyester resins, preferably acrylic resins, or as a polymer modifier, for example as polymer crosslinking agent, grafting agent or rheology modifier, preferably as polymerization initiator of acrylic resins or unsaturated polyester resins.

Unsaturated polyesters are obtained by polycondensation between a dicarboxylic acid and a diol.

The dicarboxylic acids are preferably chosen from aliphatic, linear or branched diacids, and cycloaliphatic diacids.

The linear aliphatic dicarboxylic acids are preferably chosen from succinic acid, pentanedioic acid, adipic acid, heptanedioic acid, octanedioic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, octadecanedioic acid, eicosanedioic acid, docosanedioic acid and fatty acid dimers containing 36 carbons.

The cycloaliphatic dicarboxylic acids can comprise the carbon skeletons norbornyl methane, cyclohexylmethane, dicyclohexylmethane, dicyclohexylpropane, di(methylcyclohexyl) and di(methylcyclohexyl)propane.

Preferably, the dicarboxylic acids are chosen from linear aliphatic dicarboxylic acids.

The diols are preferably chosen from the group consisting of linear aliphatic diols such as ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexylene glycol, branched diols such as as neopentyl glycol, 3-methylpentane glycol, 1,2-propylene glycol, and cyclic diols such as 1,4-bis(hydroxymethyl)cyclohexane and 1,4-cyclohexane-dimethanol.

Preferably, the polyester belongs to the polyadipate family.

The acrylic polymers are preferably polyalkyl methacrylates or polyalkyl acrylates. The alkyl group or the corresponding alkyl methacrylate or alkyl acrylate monomers consist of C ₁ -C ₁₂ alkyl groups.

Preferably, the acrylic resin is a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate.

Process

As indicated above, the method according to the invention comprises a step a) of adding a binder in the molten state as defined above, to a mixture comprising a solid organic peroxide as defined above and at least one phlegmatizing agent as defined above.

Preferably, said mixture comprises a solvent.

Preferably, the organic peroxide and said phlegmatizer are not soluble in the solvent. Preferably said mixture is a suspension.

Preferably, the solvent is selected from the group consisting of water, methanol and hydrocarbons, preferably and water.

Preferably, said solvent is present in the mixture in a content by weight ranging from 60 to 95%, more preferably ranging from 70 to 90%, more preferably from 75 to 85% relative to the total weight of said mixture.

Preferably, said organic peroxide is present in the mixture in a content by weight ranging from 0.5 and 32% relative to the total weight of the mixture.

Preferably, said phlegmatizer is present in the mixture in a content by weight ranging from 0.95 and 36% relative to the total weight of the mixture.

Preferably, said binder and said phlegmatizer are different.

However, in a particular embodiment, said binder and said phlegmatizer are identical.

Advantageously, step a) is preceded by a step a′) of mixing said at least one solid organic peroxide and said at least one solid phlegmatizing agent in a solvent.

Preferably, no heating is carried out during step a), said binder being melted beforehand.

Preferably, no heating is carried out during step a′).

Even more preferentially, no heating is carried out during steps a) and a′).

Preferably, the method according to the invention comprises, before step a′) of mixing the solid organic peroxide and the phlegmatizing agent, a step a′′) of reducing the size of the particles of the solid organic peroxide and/ or phlegmatizing agent.

Advantageously, steps a′) of mixing and a′′) of reducing the size of the particles of the solid organic peroxide and/or of the phlegmatizing agent are carried out simultaneously.

Step a'') of reducing the size of the particles of the solid organic peroxide, as defined above, and of the solid phlegmatizing agent, as defined above, is preferably carried out by implementing a process grinding or mixing with stirring, at room temperature, in the solvent as defined above.

By stirring is meant stirring carried out by means of a homogenizer of the rotor/stator type, the speed of rotation of which preferably oscillates from 200 to 4000 rpm, preferably from 300 to 3500 rpm.

The grinding or mixing process includes the use of a grinder or a mixing device.

The reduction in the size of the particles of the solid organic peroxide and the reduction in the size of the particles of the phlegmatizing agent can be carried out sequentially or simultaneously in a solvent as defined previously.

Preferably, the particle size reduction of the solid organic peroxide and the particle size reduction of the phlegmatizing agent are carried out sequentially.

Preferably, the reduction in the size of the particles of the phlegmatizing agent is carried out before the reduction in the size of the particles of the solid organic peroxide.

Preferably, the step of reducing the particle size of the solid organic peroxide and the solid phlegmatizing agent successively comprises:

• the addition of the solid phlegmatizing agent as defined above in a solvent as defined above,
• mixing with stirring, at room temperature, at a speed ranging from 200 to 4000 rpm of the solid phlegmatizing agent in the solvent,
• the addition of the solid organic peroxide, as defined previously, in the said aqueous solution with stirring, at room temperature, at a speed ranging from 200 to 4000 rpm.

Preferably, the method according to the invention further comprises the addition of at least one mineral filler as defined above, preferably a silica, preferably after step a) of adding the binder.

Preferably, at least one dispersing agent as described above is added with the solid phlegmatizing agent in the solvent.

The solid organic peroxide and the phlegmatizing agent are then mixed together, preferably until a suspension is obtained.

Preferably, the binder in the solid state is added in a solvent as defined above and then is heated to a temperature above its melting point so as to melt it.

The molten binder is then added to the mixture, preferably with stirring at a speed ranging from 200 to 3000 rpm.

Preferably, at least one mineral filler, as defined above, is added to the mixture, advantageously after step a) of adding the molten binder.

Preferably, at least one anti-caking agent and/or dust suppressant is added to the mixture, advantageously after the addition of the molten binder.

A step for homogenizing the mixture can be implemented after adding the mineral filler and/or the anti-caking agent and/or dust suppressant.

Preferably, the process according to the invention further comprises a step b) of filtration of the composition obtained in step a) so as to eliminate all or part of the solvent.

Step b) of filtration of the composition is preferably carried out by a sieving process, preferably with a 25 micrometer filter sieve.

Preferably, the method according to the invention may also comprise a step c) of drying the composition.

Step c) of drying is preferably implemented in a rotary evaporator, for example at a temperature of approximately 40° C. at a pressure of approximately 53 bar for a period of 2 hours.

Preferably, the composition obtained after step c) is anhydrous.

The process according to the invention also preferably comprises a step d) of sieving the composition, in particular carried out using a sieve provided with several types of openings, preferably with three types of openings, such as 800 micrometers, 500 micrometers and 100 micrometers.

The method according to the invention may also comprise a step of recovering the anhydrous composition in solid form having a particle size greater than or equal to 100 micrometers and less than 500 micrometers.

Advantageously, the method according to the invention successively comprises two, preferably three, more preferably four, more preferably five, and particularly preferably all of the following steps:

• a step of reducing the size of the particles of at least one solid organic peroxide as defined above and/or of at least one solid phlegmatizing agent as defined above,
• a step a′) of mixing the solid organic peroxide and the phlegmatizing agent thus obtained,
• a step a) of adding a binder in the molten state as defined above, in said mixture,
• a filtration step b) of said mixture so as to remove all or part of the solvent,
• a drying step c) of the composition,
• a sieving step d) of the composition.

The present invention also relates to the composition capable of being obtained by the preparation process as defined previously.

The following examples serve to illustrate the invention without, however, being of a limiting nature.

EXAMPLE

A. Preparation of a solid organic peroxide composition comprising 50% by weight of dibenzoyl peroxide, 45% by weight of benzoic acid and 5% by weight of lauric acid

Add benzoic acid in the solid state (90g), benzoyl peroxide (75% dephlegmatized dibenzoyl peroxide with 25% water, sold under the name Luperox® A75), (133g, i.e. 100g of pure dibenzoyl peroxide) and a dispersing agent, sold under the trade name Coadis® OP10 (0.9g) in an aqueous solution (745g of water) at a temperature of 20°C.

The whole is then mixed using a shear blade rotor/stator with stirring at 3000 rpm at room temperature for a period of 1 hour 30 minutes.

Separately from this preparation, lauric acid (10g) in the solid state is added to a beaker filled with water at a temperature of 60°C for a sufficient time to melt it.

Dibenzoyl peroxide, sold under the name Luperox® A75, is then gradually added to the aqueous phase of the composition comprising the benzoic acid with stirring at 400 rpm for a period of 20 minutes.

The whole is mixed so as to obtain a suspension.

The lauric acid is then introduced in the molten state into the reaction medium with stirring at 1100 rpm for a period of 30 minutes.

The paste thus obtained is filtered through a 25 micron filter screen.

The composition is then dried in the form of a paste in a rotary evaporator at a temperature of 40° C. and a pressure of 53 bars for a period of two hours.

After drying, the product is filtered with a sieve having three types of openings 800 micrometers, 500 micrometers and 100 micrometers.

B. Particle size distribution

Following the method as described above, the particle size distribution of the solid dibenzoyl peroxide compositions is analyzed. The size and particle size distribution of the composition are measured by dry sieving, carried out by a VE 1000 sieve from RETSCH, operating for 20 minutes at an angle of oscillation of 1.5 mm.

Table 1: Particle size distribution obtained after implementation of the process

Particle size
(µm)
800
630
500
315
200
100
75
<75 g-residues 0.5 6.42 8.44 12.7 11.46 17.02 13.87 6.87 Residues
%
0.65
8.31
10.92
16.43
14.83
22.02
17.95
8.89 Residues
% by particle class
19.9%
53.3%
26.8% Class of
particles ≥ 500µm ]500µm – 100µm] < 100 µm

C.Conclusion

It is observed that the majority (i.e. of the order of 53%) of particles of composition of dibenzoyl peroxide mixed with benzoic acid and lauric acid having a size greater than or equal to 100 μm and less than 500 µm.

As a result, a narrow particle size distribution is obtained around this range of values.

D. Preparation of a solid organic peroxide composition comprising 50% by weight dibenzoyl peroxide, 41% by weight benzoic acid, 5% by weight lauric acid and 4% by weight silica

• The same process as that described in part A is implemented by adding 4% by weight of a hydrophobic silica, sold under the name Aerosil R972 (8g) with stirring at 1100 rpm for a period of 10 minutes, after the step of adding lauric acid in the molten state. The following quantities were used: benzoic acid in solid state: 82g,
• benzoyl peroxide (75% dephlegmatized dibenzoyl peroxide with 25% water, sold as Luperox® A75): 133g
• dispersing agent, sold under the trade name Coadis® OP10: 0.9g
• lauric acid: 10g
• water: 745g.

E. Particle size distribution

Following the method as described above, the particle size distribution of the solid dibenzoyl peroxide composition is analyzed. The size and the particle size distribution of the composition are measured by dry sieving, carried out by a VE 1000 sieve from RETSCH, operating for 20 minutes at an angle of oscillation of 1.5 mm.

Table 2: Particle size distribution obtained after implementation of the process

Particle size
(µm)
≥ 800
]800µm – 100µm]
]500µm – 100µm]
< 100 g-residues 0.63 1.62 184.15 1 Residues
% 0.34% 0.86% 98.27% 0.53%

F.Conclusion

It is observed that the majority (i.e. of the order of 98%) of particles of composition of dibenzoyl peroxide mixed with benzoic acid, lauric acid and silica having a size greater than or equal to 100 are obtained. µm and less than 500 µm.

It is observed more particularly that the presence of silica makes it possible to limit the percentage of particles having a size greater than or equal to 500 μm with respect to the particle size distribution detailed in Table 1.

G. Preparation of a solid organic peroxide composition comprising 50% by weight of dibenzoyl peroxide and 50% by weight of benzoic acid

The same process as described in part A is carried out, except that no lauric acid is added to the suspension and that 100g of benzoic acid has been used.

H. Particle size distribution of the product obtained

Table 3: Particle size distribution obtained after implementation of the process

Particle size
(µm)
≥ 800
]800µm – 100µm]
]500µm – 100µm]
< 100
≥ 800
]800µm – 100µm] g-residues 46.2 12 9.1 2.2 20.6 18.1 Residues
% 42.8 11 8.4 2 19 16.7 Residues
% by particle class
53.8%
29.4%
16.8% Class of
particles ≥ 500µm ]500µm – 100µm] <100µm

It is observed that the majority (i.e. of the order of nearly 53%) of particles of composition of dibenzoyl peroxide mixed with benzoic acid having a size greater than 500 μm are obtained.

Consequently, the dibenzoyl peroxide repair is not homogeneous across the different fractions of particles because it is mainly formulated in particles having a size greater than 500 µm.

In addition, it is observed that the percentage yield of particles having a size greater than or equal to 100 μm and strictly less than 500 μm is lower than that obtained in tables 1 and 2.

Claims (15)

Composition comprising:

• at least one solid organic peroxide,
• at least one solid phlegmatizing agent, preferably having a melting point greater than or equal to 40°C, and
• at least one solid binder having an enthalpy of fusion greater than or equal to 125 kJ/kg, preferably ranging from 145 kJ/kg to 250 kJ/kg.

Composition according to Claim 1, characterized in that the organic peroxide is chosen from the group consisting of solid diacyl peroxides, solid peroxydicarbonates, solid ketone peroxides, solid peroxy esters, solid hydroperoxides, solid dialkyl peroxides and mixtures thereof, preferably solid diacyl peroxides. Composition according to any one of the preceding claims, characterized in that it comprises:

• from 10 to 80% by weight, preferably from 15% to 75% by weight, and more preferably from 20 to 60% by weight of said at least one organic peroxide;
• from 19 to 89% by weight, preferably from 20% to 75% by weight of said at least one phlegmatizing agent; And
• from 1 to 40% by weight, preferably from 2% to 15% by weight of said at least one binder
  relative to the total weight of the composition.

Composition according to any one of the preceding claims, characterized in that the solid phlegmatizing agent is chosen from the group consisting of saturated carboxylic acids comprising at least 11, preferably at least 12 carbon atoms, linear or branched, substituted or no, carboxylic acids comprising at least one aromatic ring, substituted or unsubstituted, and mixtures thereof, preferably carboxylic acids comprising at least one aromatic ring. Composition according to any one of the preceding claims, characterized in that the solid phlegmatizing agent is a benzoic acid optionally substituted by one or more alkyl groups, in particular C ₁ -C ₁₀ . Composition according to any one of the preceding claims, characterized in that the solid binder is chosen from the group consisting of solid fatty acids, solid fatty acid esters, solid waxes and mixtures thereof, preferably solid fatty acids . Composition according to any one of the preceding claims, characterized in that the solid binder is a fatty acid chosen from the group consisting of lauric acid, myristic acid, capric acid, palmitic acid, stearic acid and mixtures thereof, more preferably lauric acid. Composition according to any one of the preceding claims, characterized in that it also comprises at least one mineral filler, preferably a silica. Composition according to any one of the preceding claims, characterized in that at least 50% by weight of the particles have a size greater than or equal to 100 micrometers and less than 500 micrometers, preferably at least 60%, more preferably 70%, more preferably 80% and particularly preferably 90% by weight of the particles have a size greater than or equal to 100 micrometers and less than 500 micrometers. Use of the composition as defined according to any one of the preceding claims as an initiator for the polymerization of acrylic resins or unsaturated polyester resins, preferably acrylic resins, or as a polymer modifier, for example as an polymer crosslinker, grafting agent, or rheology modifier. Process for the preparation of a composition comprising a step a) of adding a binder, as defined according to any one of Claims 1, 6 and 7, in the molten state, into a mixture comprising a solid organic peroxide as defined in claim 1 or 2, and at least one phlegmatizing agent as defined in any one of claims 1, 4 and 5. Process according to claim 11, characterized in that step a) is preceded by a step a') of mixing said at least one solid organic peroxide and said at least one solid phlegmatizing agent in a solvent. Process according to Claim 11 or 12, characterized in that it further comprises the addition of at least one mineral filler, preferably a silica, preferably after step a) of adding the molten binder. Process according to any one of Claims 11 to 13, characterized in that it also comprises, before step a') of mixing the solid organic peroxide and the phlegmatizing agent, a step a'') of reducing the particle size of the solid organic peroxide and/or the phlegmatizing agent. Process according to any one of Claims 11 to 14, characterized in that it successively comprises two, preferably three, more preferably four, more preferably five, and particularly preferably all of the following steps:

• a step of reducing the size of the particles of at least one solid organic peroxide as defined above and/or of at least one solid phlegmatizing agent as defined above,
• a step a′) of mixing the solid organic peroxide and the phlegmatizing agent thus obtained,
• a step a) of adding a binder in the molten state as defined above, to said mixture,
• a filtration step b) of said mixture so as to eliminate all or part of the solvent,
• a drying step c) of the composition,
• a sieving step d) of the composition.