Process for the preparation of a composition in powder form comprising at least one solid organic peroxide

Abstract

TITLE: Process for the preparation of a composition in powder form comprising at least one solid organic peroxide The present invention relates to a process for the production of a powder composition comprising at least one solid organic peroxide having the advantages of having a reduced water content and being able to flow easily. The invention also relates to a powder composition which can be obtained from the process as defined below. The present invention further relates to the use of said powder composition as a polymerization initiator for acrylic resins or unsaturated polyester resins, preferably acrylic resins, or as a polymer modifier, for example as a crosslinking agent, grafting agent or polymer rheology modifier, preferably as a polymerization initiator for acrylic resins or unsaturated polyester resins.The invention further relates to the use of said powder composition for road marking, chemical anchoring, waterproofing and flooring applications, preferably road marking.

Description

Title of the invention: Process for the preparation of a composition in powder form comprising at least one solid organic peroxide Field of invention

[0001] The present invention relates to a process for the production of a powder composition comprising at least one solid organic peroxide advantageously offering the advantages of having a reduced water content and being able to flow easily.

[0002] The invention also relates to a powder composition which can be obtained from the process as defined below.

[0003] The present invention further relates to the use of said powder composition as a polymerization initiator for acrylic resins or unsaturated polyester resins, preferably acrylic resins, or as a polymer modifier, for example as a crosslinking agent, grafting agent or polymer rheology modifier, preferably as a polymerization initiator for acrylic resins or unsaturated polyester resins.

[0004] The invention further relates to the use of said powder composition for road marking, chemical anchoring, waterproofing and floor covering applications, preferably road marking. Background to the invention

[0005] Acrylic resins and polyester resins are currently used in many different technical fields for industrial or decorative applications, for example for the preparation of paints, in particular for road marking, the protection of structures and the waterproofing of floors, the manufacture of chemical sealants (also called chemical anchors) in order to fix objects of varying sizes on many surfaces, the production of composite materials in association with reinforced fibers, the manufacture of marbles, natural or synthetic, as well as mastics in particular used for the repair of car bodies.

[0006] Acrylic resins are mainly appreciated by users for their rapid curing, even at low temperatures, for example at temperatures around 10 °C, their strong adhesion to countless types of substrates as well as their high mechanical strength, while polyester resins have very good resistance to chemicals, especially in acidic environments, good properties in terms of mechanical strength and rapid commissioning.

[0007] Such resins also offer the advantage of being able to be applied manually or by spraying, in particular by the use of various spraying techniques, on several types of surfaces.

[0008] Acrylic resins and polyester resins are mostly obtained by polymerization, in particular by radical polymerization of one or more acrylic monomers, identical or different, in the presence of organic peroxides, in liquid or solid form, acting as polymerization initiators.

[0009] A difficult aspect of using organic peroxides is that they are usually highly unstable species when heated, as they decompose relatively easily under the action of a small amount of heat. Thus, in the event of an uncontrolled rise in their storage temperature, some organic peroxides may undergo self-accelerating exothermic decomposition leading to fires and / or violent explosions. Moreover, under these conditions, some of these organic peroxides release combustible vapors which can react with any source of ignition, which can significantly increase or even accelerate the risk of explosion with bursting.

[0010] Indeed, such organic peroxides have a self-accelerating decomposition temperature (SADT) which corresponds to the lowest temperature at which an uncontrolled reaction occurs, i.e. a self-accelerating decomposition in its packaging. In other words, the self-accelerating decomposition temperature SADT represents the temperature at which the chemical process leading to uncontrolled decomposition, possibly accompanied by self-combustion and explosion phenomena, begins.

[0011] Such risky behavior is therefore incompatible with the rules in force for the transport and storage of dangerous goods. It is particularly important to take adequate and stringent precautionary measures when storing and handling such organic peroxides, in particular ensuring that they remain at temperatures below their self-accelerating decomposition temperature SADT in order to minimize the risk of fire and / or uncontrolled decomposition. Therefore, in some cases, such precautionary measures involve maintaining the organic peroxides at a storage temperature which is preferably at least 10 °C, and preferably even further at least 20 °C, below the self-accelerating decomposition temperature SADT.

[0012] In order to overcome these various drawbacks, such organic peroxides can be diluted or mixed with inert products, for example products which are not reactive in contact with said organic peroxides, called phlegmatizing agents. In particular, phlegmatizing agents make it possible to limit the effects of uncontrolled decomposition of organic peroxides and therefore to reduce the various risks associated with their manipulation.

[0013] Accordingly, organic peroxides can be solubilized in a liquid phlegmatizer or mixed with a solid inert phlegmatizer or even be implemented in the form of an emulsion in the liquid phlegmatizer. For example, solid organic peroxides can be mixed with water to form a powder moistened with water.

[0014] Although the presence of water in such solid organic peroxide formulations may mitigate safety concerns, it may also disrupt or even hinder their final application. For example, the presence of water may cause the formation of several small air bubbles or lumps on the surface of the acrylic paint during polymerization, which may hinder its use. In addition, the presence of water in the solid organic peroxide formulation hinders its flow properties, making it more prone to caking during transportation and storage.

[0015] Furthermore, implementing a drying process to evaporate the aqueous phase contained in solid organic peroxide formulations can be tricky since it requires heating such formulations to a temperature close to or higher than the self-accelerating decomposition temperature SADT of the organic peroxide, which causes its chemical degradation. In other words, there is a fairly high risk that implementing such a drying process could trigger the safety issues previously described.

[0016] Therefore, there remains a real need to provide a method for producing a powder composition comprising a solid organic peroxide having a low water content and being easily flowable, without triggering during its implementation the safety problems linked to the uncontrolled chemical decomposition of the organic peroxide.

[0017] In other words, one of the aims of the present invention is to safely produce a pourable product comprising a solid organic peroxide which is ready for use and which can be manufactured without hindrance in its intended end application. Description of the invention

[0018] The present invention results in particular from the unexpected findings, by the inventors, that the implementation of a process as described below makes it possible to achieve the above-mentioned objectives.

[0019] Therefore, the present invention relates to a process for the production of a composition in powder form, comprising the steps of:

[0020] a) mixing at least one organic solvent, at least one solid organic peroxide and an aqueous phase,

[0021] b) reducing the aqueous phase of said mixture,

[0022] c) mixing at least one inert filler, preferably at least two inert fillers, with the resulting composition in order to obtain a powder composition comprising said solid organic peroxide.

[0023] The method according to the present invention makes it possible to safely obtain a flowable powder composition comprising at least one solid organic peroxide which is ready for use and which can be manufactured without hindrance in its final application.

[0024] In other words, the process of the present invention results in a powder composition, preferably having fine particles, which has the advantages of being able to flow easily and having a low water content.

[0025] The implementation of such a method makes it possible to restrict the risks linked to the uncontrolled chemical decomposition of the organic peroxide, in particular by not carrying out a drying step for the removal of the aqueous phase present in the composition comprising said organic peroxide.

[0026] This means that the process of the invention minimizes the risks of exothermic decomposition during the preparation of the powder composition.

[0027] The process according to the present invention has the additional advantage of producing a powder composition comprising at least one solid organic peroxide which is ready to be mixed with acrylic or polyester resins since it does not require further removal of its residual water content. In fact, the residual water content of the composition obtained does not hinder its final application.

[0028] Furthermore, the process can be easily optimized and monitored on a laboratory scale as well as on a large-scale production. Indeed, the process according to the invention is easy to implement and consumes a low amount of energy.

[0029] In other words, the method according to the present attention has the advantage of avoiding a drying step, which is a large energy consumer and concerned by a safety risk.

[0030] The present invention also relates to a composition in powder form comprising:

[0031] - at least one solid organic peroxide,

[0032] - at least one inert filler, preferably at least two inert fillers,

[0033] - at least one organic solvent and

[0034] - an aqueous phase, preferably water.

[0035] The composition according to the present invention is a non-agglomerating powder having excellent fluid flow properties.

[0036] Indeed, the powder composition according to the present invention has the advantage of having a poured cone height preferably less than or equal to 3 cm. The lower the poured cone height, the better the flowability of the powder.

[0037] The measurement of the poured cone height under defined conditions of the powder composition according to the present invention can be carried out by a Pfrengle test according to DIN 53 916.

[0038] The powder composition according to the present invention also offers the advantage of generating little or no dust.

[0039] The composition as defined exhibits the desired average particle size and a homogeneous particle size distribution while remaining stable, both during storage and during handling.

[0040] The composition according to the present invention advantageously responds to the problems of application, in particular on road marking.

[0041] The present invention further relates to the use of said powder composition as a polymerization initiator, in particular for acrylic resins or unsaturated polyester resins, preferably acrylic resins, or as a polymer modifier, for example as a crosslinking agent, grafting agent or polymer rheology modifier, preferably as a polymerization initiator for acrylic resins or unsaturated polyester resins, in particular acrylic resins.

[0042] Indeed, the powder composition according to the invention proves to be compatible with the acrylic resins and the polyester resins obtained, preferably with the acrylic monomers, which reduces to a minimum, for example, the risks of the appearance of air bubbles when obtaining such resins, in particular when obtaining an acrylic paint.

[0043] Another object of the invention is the use of said composition for road marking, chemical anchoring, waterproofing and floor covering applications, preferably road marking.

[0044] Other subjects and characteristics, aspects and advantages of the invention will emerge even more clearly from reading the description and examples which follow.

[0045] In the text below, and unless otherwise indicated, the limits of a range of values ​​are included in this range, in particular in the expressions "between" and "ranging from...to...".

[0046] Furthermore, the expression “at least one” used in the present description is equivalent to the expression “one or more”.

[0047] In the text below, the terms “peroxyketal” and “perketal” are equivalent.

[0048] Still further, the term "polymer" encompasses "homopolymers" and "copolymers", the term "copolymers" referring to a polymer consisting of at least two different monomers in polymerized form. For example, a co A polymer according to the present disclosure may be a polymer comprising two different monomers, a terpolymer being a polymer comprising three or more different monomers. Composition

[0049] As detailed above, the present invention relates to a composition in powder form comprising at least one solid organic peroxide, at least one organic solvent, at least one inert filler, preferably at least two inert fillers, and an aqueous phase, preferably water.

[0050] According to the present invention, by the expression "solid organic peroxide" it should be understood that said organic peroxide is in a solid state at room temperature and under atmospheric pressure (approximately 1 bar or 1.013 x 105 Pa).

[0051] For the purposes of the present invention, the term "room temperature" means a temperature ranging from 15°C to 27°C, preferably from 20°C to 25°C.

[0052] Preferably, the solid organic peroxide is selected from the group consisting of solid diacyl peroxides, solid peroxydicarbonates, solid ketone peroxides, solid peroxyesters, solid hydroperoxides, solid dialkyl peroxides and mixtures thereof, preferably selected from the group consisting of solid diacyl peroxides, solid peroxydicarbonates and mixtures thereof, more preferably selected from the group consisting of solid diacyl peroxides.

[0053] The solid diacyl peroxides are preferably selected from the group consisting of dibenzoyl peroxide, di(2-methylbenzoyl) peroxide, di(methoxybenzoyl) peroxide, di(2-methoxycarbonylbenzoyl) peroxide, di(2-benzylbenzoyl) peroxide, di(4-fluorobenzoyl) peroxide, di(3-chlorobenzoyl) peroxide, di(4-chlorobenzoyl) peroxide, di(2,4-dichlorobenzoyl) peroxide, dibenzoyl diperoxyadipate, benzoyl octadecanoyl peroxide, dilauroyl peroxide, dihexadecanoyl peroxide, di(chloroacetyl) peroxide and di(3-carboxypropionyl) peroxide.

[0054] The solid peroxydicarbonates are preferably dialkyl peroxydicarbonates, in particular selected from the group consisting of dibenzyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, di(cA-3,3,5-trimethylcyclohexyl) peroxydicarbonate, di(4-t-butylcyclohexyl) peroxydicarbonate, dibornyl peroxydicarbonate, di(2-phenoxyethyl) peroxydicarbonate, di-n-tridecyl peroxydicarbonate and di-n-hexadecyl peroxydicarbonate.

[0055] The solid ketone peroxides are preferably selected 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.

[0056] The solid peroxyesters are preferably selected from the group consisting of di-t-butyl diperoxyterephthalate, di-t-butyl diperoxysuccinate, di-t-butyl diperoxyadipate, di-t-butyl diperoxyphthalate, t-butyl peroxy(3-carboxypropionate), t-butyl peroxy(3-carboxy-2-propenoate) and 2,5-dimethyl-2,5-di(benzoylperoxy)hexane.

[0057] The solid alkyl hydroperoxides are preferably selected from the group consisting of 2,5-dimethyl-2,5-dihydroxyperoxyhexane, 2,5-dimethyl-2,5-dihydroxypoxy-3-hexane, 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.

[0058] The solid dialkyl peroxides are preferably selected from the group consisting of dicumyl peroxide, 1,4-di[1-methyl-1-(t-butylperoxy)ethyl]benzene, 1,3-di[1-methyl-1-(t-butylperoxy)ethyl]benzene and di(isopropylcumyl) peroxide.

[0059] Preferably, the solid organic peroxide is selected from the group consisting of solid diacyl peroxides, solid peroxydicarbonates and mixtures thereof. Even more preferably, the solid organic peroxide is selected from the group consisting of solid diacyl peroxides, in particular dibenzoyl peroxide.

[0060] Preferably, the solid organic peroxide is dibenzoyl peroxide.

[0061] The mixture preferably includes dibenzoyl peroxide such as the product sold under the trade name Luperox® A75 by the company Arkema.

[0062] The solid organic peroxide is preferably present in a content ranging from 10 to 60% by weight, relative to the total weight of the powder composition.

[0063] According to a preferred embodiment, the solid organic peroxide is present in a content ranging from 20 to 60% by weight, preferably from 30 to 55% by weight, more preferably from 40 to 55% by weight, relative to the total weight of the powder composition.

[0064] Preferably, the organic solvent has a solubility of less than 5 mg / l, preferably less than 1 mg / l, preferably less than 0.1 mg / l in water at room temperature, in particular at a temperature ranging from 15°C to 27°C, preferably from 20°C to 25°C, under atmospheric pressure (approximately 1 bar or 1.013 x 105 Pa).

[0065] Preferably, the solid organic peroxide has a solubility of less than 5% by weight, preferably less than 1% by weight, preferably less than 0.1% by weight in the organic solvent at room temperature, in particular at a temperature ranging from 15°C to 27°C, preferably from 20°C to 25°C, under atmospheric pressure (approximately 1 bar or 1.013 x 105 Pa).

[0066] Preferably, the organic solvent has a solubility of less than 5 mg / l, preferably less than 1 mg / l, preferably less than 0.1 mg / l in water at room temperature, in particular at a temperature ranging from 15°C to 27°C, preferably from 20°C to 25°C, under atmospheric pressure (approximately 1 bar or 1.013 x 105 Pa) and the solid organic peroxide has a solubility of less than 5% by weight, preferably less than 1% by weight, preferably less than 0.1% by weight in the organic solvent at room temperature, in particular at a temperature ranging from 15°C to 27°C, preferably from 20°C to 25°C, under atmospheric pressure (approximately 1 bar or 1.013 x 105 Pa).

[0067] The organic solvent is in particular liquid up to a temperature strictly lower than the self-accelerated decomposition temperature TDAA of said organic peroxide.

[0068] The term "self-accelerating decomposition temperature SADT of organic peroxide" within the meaning of the present invention means the lowest temperature at which an exothermic decomposition of the organic peroxide begins in its packaging, preferably according to UN Test H.4, as described in the UN Manual of Tests and Criteria, 7th revised edition of 2019.

[0069] For the purposes of the present invention, by the expression "the organic solvent which is liquid up to a temperature strictly lower than the self-accelerating decomposition temperature TDAA of said organic peroxide" it is understood that the organic solvent remains in a liquid state up to a temperature strictly lower than the lowest temperature at which an exothermic decomposition of the organic peroxide begins in its packaging, preferably according to UN test H.4.

[0070] According to a preferred embodiment, the organic solvent (or the mixture of organic solvents) is in a liquid state at a temperature between 4°C and a temperature strictly lower than the self-accelerated decomposition temperature TDAA of said organic peroxide, preferably at a temperature between 15°C and a temperature strictly lower than the self-accelerated decomposition temperature TDAA of said organic peroxide.

[0071] According to a preferred embodiment, the organic solvent is in a liquid state at a temperature between 15°C and at least 10°C lower, preferably at least 20°C lower, than the self-accelerating decomposition temperature TDAA of said solid organic peroxide.

[0072] According to a preferred embodiment, the organic solvent is in a liquid state at a temperature ranging from 15°C to a temperature strictly below 75°C, preferably from 25°C to 65°C, more preferably from 35°C to 60°C, even more preferably from 45°C to 55°C.

[0073] Advantageously, the organic solvent is an organic solvent which is not a phthalate, preferably a plasticizer which is not a phthalate.

[0074] Advantageously, the organic solvent has a very good toxicological profile and has been authorized for sensitive applications by the competent authorities.

[0075] In particular, the organic solvent has the advantage of being authorized for food contact applications.

[0076] Preferably, the organic solvent is authorized for food uses.

[0077] Preferably, when the organic solvent has a solubility of less than 5 mg / l in water at room temperature, preferably less than 1 mg / l in water at room temperature, preferably less than 0.1 mg / l in water at room temperature and the solid organic peroxide has a solubility of less than 5% by weight in the organic solvent at room temperature, preferably less than 1% by weight in the organic solvent at room temperature, preferably less than 0.1% by weight in the organic solvent at room temperature, the organic solvent may be selected from the group consisting of esters, in particular esters of monocarboxylic, dicarboxylic, tricarboxylic and polycarboxylic acids reacted with monoalcohols, diols, triols or polyols, alcohols, alkanes and mineral oils.

[0078] The organic solvent is preferably selected from the group consisting of alkyl esters of diacids, cyclohexanedicarboxylates, esters based on glycols, polyglycols and polyols and mixtures thereof, preferably from the group consisting of cyclohexanedicarboxylates and alkyl esters of diacids and mixtures thereof.

[0079] Suitable dibasic acid alkyl esters may be selected from C4-C12 alkyl esters of dicarboxylic acids such as adipic, sebacic, azelaic and maleic acids.

[0080] The alkyl esters of dicarboxylic acids may be selected from C4-C12 alkyl esters of dicarboxylic acids preferably selected from the group consisting of bis(2-ethylhexyl) adipate (DEHA), dimethyl adipate (DMAD), monomethyl adipate (MMAD), dioctyl adipate (DOA), dibutyl sebacate (DBS), dibutyl maleate (DBM), diisobutyl maleate (DIBM), dioctyl sebacate (DOS) and mixtures thereof.

[0081] Suitable glycol, polyglycol and polyol based esters may be selected from the group consisting of poly(ethylene glycol) monoesters and diesters, cyclohexanedimethanol esters, sorbitol derivatives; and triethylene glycol dihexanoate, diethylene glycol di-2-ethylhexanoate, tetraethylene glycol di-heptanoate and ethylene glycol dioleate and mixtures thereof.

[0082] Preferably, the organic solvent is selected from the group consisting of cyclohexanedicarboxylates, alkyl esters of diacids and mixtures thereof. ci, in particular in the group consisting of cyclohexanedicarboxylates, C4-Ci2 alkyl esters of dicarboxylic acids and mixtures thereof.

[0083] Preferably, the organic solvent is selected from cyclohexanedicarboxylates, more preferably diisononyl 1,2-cyclohexanedicarboxylate, for example diisononyl 1,2-cyclohexanedicarboxylate available under the trade name HEXAMOLL DINCH® from BASF.

[0084] HEXAMOLL DINCH has the advantage of being able to be used for applications sensitive human products, such as food packaging, medical products and toys.

[0085] In particular, HEXAMOLL DINCH has the advantage of being able to be used for food contact applications.

[0086] The organic solvent may be present in the powder composition in a concentration ranging from 5 to 50% by weight, preferably from 10% to 30% by weight, even more preferably from 15% to 25% by weight, relative to the total weight of said powder composition.

[0087] As detailed above, the composition according to the present invention further comprises at least one inert filler, preferably at least two inert fillers.

[0088] The inert filler is preferably selected from inert fillers which are soluble in acrylic and / or polyester resins, preferably soluble in acrylic resins, at room temperature, in particular at a temperature ranging from 15°C to 27°C, preferably from 20°C to 25°C.

[0089] According to the present invention, by the term "inert filler" it is understood that the filler does not trigger the exothermic decomposition of said organic peroxide. In other words, the presence of the filler does not accelerate the exothermic decomposition of said organic peroxide.

[0090] Preferably, the inert filler is other than carbon black.

[0091] Preferably, the inert filler is chosen from the group consisting of fillers inorganic inerts.

[0092] The inert filler is preferably selected from the group consisting of silicas, more preferably selected from the group consisting of silicas obtainable from a precipitation process.

[0093] The inert filler is preferably selected from the group consisting of hydrophobic silicas, hydrophilic silicas and mixtures thereof.

[0094] The inert filler is preferably selected from combinations of dual-functional silicas. In particular, the inert filler is advantageously selected from combinations of at least one hydrophobic silica and at least one hydrophilic silica.

[0095] Advantageously, the presence of a combination of at least one hydrophobic silica and at least one hydrophilic silica improves the flowability of the powder composition.

[0096] The inert filler is preferably selected from the silicas sold by the company Evonik under the trade names SIPERNAT®.

[0097] In particular, the inert filler may be selected from the group consisting of hydrophobic silicas, such as silicas sold under the trade name SIPERNAT® D17, hydrophilic silicas, such as silicas sold under the trade name SIPERNAT® 2200, and mixtures thereof.

[0098] Preferably, the inert filler is selected from the combinations of at least one hydrophobic silica sold under the trade name SIPERNAT® D17 and at least one hydrophilic silica sold under the trade name SIPERNAT® 2200.

[0099] The composition comprises at least one inert filler, in particular at least two inert fillers, preferably in a concentration ranging from 5% to 50% by weight, more preferably from 10% to 30% by weight, even more preferably from 15% to 25% by weight, relative to the total weight of said powder composition. When at least two inert fillers are present, the preferred total concentration of the fillers ranges from 5% to 50% by weight, more preferably from 10% to 30% by weight, even more preferably from 15% to 25% by weight, relative to the total weight of said powder composition.

[0100] The composition may further comprise at least one powder having a crystalline structure and a melting temperature ranging from 30°C to 80°C in order to advantageously reduce the abrasiveness of said powder composition.

[0101] The powder having a crystalline structure and a melting temperature ranging from 30°C to 80°C can be selected from solid fatty acids.

[0102] The solid fatty acids are preferably linear or branched and comprise in their structure a number of carbon atoms ranging from 6 to 20, preferably ranging from 10 to 20, more preferably ranging from 12 to 20, even more preferably from 14 to 20, in particular from 16 to 20.

[0103] Preferably, the fatty acids are selected from the group consisting of lauric acid, myristic acid, capric acid, palmitic acid, stearic acid and mixtures thereof.

[0104] Even more preferably, the solid fatty acid is stearic acid, for example stearic acid sold under the trade name EDENOR® STI GS by the company EMERY.

[0105] According to a preferred embodiment, the composition comprises at least one inert filler, preferably two inert fillers, selected from silicas, and at least one powder having a crystalline structure and a melting temperature ranging from 30°C at 80°C, preferably selected from solid fatty acids, in particular stearic acid.

[0106] The aqueous phase, preferably water, may be present in a concentration of up to 10% by weight (10% by weight being inclusive), relative to the total weight of the powder composition, preferably in a concentration of from 3 to 10% by weight, preferably from 4 to 7%, relative to the total weight of the powder composition, and even more preferably from 4 to 6% by weight relative to the total weight of the powder composition.

[0107] Preferably, the composition is a phthalate-free formulation.

[0108] According to a preferred embodiment, the composition comprises:

[0109] - at least one solid organic peroxide as defined above, preferably selected from diacyl peroxides,

[0110] - at least one filler chosen from the group consisting of silicas, preferably selected from the group consisting of silicas which can be obtained from a precipitation process,

[0111] - at least one organic solvent chosen from the group consisting of cyclohexane- dicarboxylates, alkyl esters of diacids and mixtures thereof, in particular from the group consisting of cyclohexanedicarboxylates, C4-C12 alkyl esters of dicarboxylic acids and mixtures thereof, and

[0112] - an aqueous phase, preferably water.

[0113] Preferably, the composition in powder form comprises:

[0114] - at least one solid organic peroxide as defined above, preferably selected from diacyl peroxides,

[0115] - a combination of at least one hydrophobic silica and at least one hy silica drophile,

[0116] - at least one organic solvent chosen from the group consisting of cyclohexane dicarboxylates, C4-C12 alkyl esters of dicarboxylic acids and mixtures thereof,

[0117] - an aqueous phase, preferably water, in a concentration of up to 10% by weight, preferably ranging from 3 to 10% by weight, in particular ranging from 4 to 7% by weight and even more preferably from 4 to 6% by weight relative to the total weight of the powder composition,

[0118] - preferably at least one powder having a crystalline structure and a temperature melting temperature ranging from 30°C to 80°C, preferably selected from solid fatty acids, in particular stearic acid.

[0119] Preferably, the composition in powder form comprises:

[0120] - at least one solid organic peroxide as defined above, preferably selected from diacyl peroxides, in a content ranging from 20 to 60% by weight, preferably from 30 to 55% by weight, more preferably from 40% to 55% by weight relative to the total weight of the powder composition,

[0121] - at least one inert filler, preferably two inert fillers, preferably selected selected from the combinations of at least one hydrophobic silica and at least one hydrophilic silica in a content ranging from 5 to 60% by weight, preferably ranging from 10 to 40% by weight, even more preferably from 15 to 35% by weight relative to the total weight of the powder composition,

[0122] - at least one organic solvent chosen from the group consisting of cyclohexane- dicarboxylates, C4-C12 alkyl esters of dicarboxylic acids and mixtures thereof, in a content ranging from 5% to 50% by weight, preferably ranging from 10 to 30% by weight, even more preferably from 15 to 25% by weight relative to the total weight of the powder composition,

[0123] - an aqueous phase, preferably water, in a concentration of up to 10% by weight, preferably ranging from 3 to 10% by weight, in particular ranging from 4 to 7% by weight, even more preferably from 4 to 6% by weight relative to the total weight of the powder composition,

[0124] - preferably at least one powder having a crystalline structure and a temperature melting temperature ranging from 30°C to 80°C, preferably selected from solid fatty acids, in particular stearic acid.

[0125] The composition may comprise one or more of the compounds chosen from the group consisting of: sodium tripolyphosphate, at least one pH modifying agent which may be chosen from alkaline agents, in particular chosen from organic or mineral alkaline agents, acidifying agents, in particular chosen from organic or mineral acids such as hydrochloric acid, phosphoric acid, lactic acid or citric acid, and mixtures thereof.

[0126] Preferably, the composition according to the present invention is a powder moistened with water. Process

[0127] As detailed above, the method according to the present invention comprises the steps of:

[0128] a) mixing at least one organic solvent as defined above, at least one solid organic peroxide as defined above and an aqueous phase, preferably water,

[0129] b) reducing the aqueous phase of said mixture,

[0130] c) mixing at least one inert filler, preferably at least two inert fillers, as defined above, with the resulting composition in order to obtain a powder composition comprising said solid organic peroxide.

[0131] According to step a), at least one organic solvent, at least one organic peroxide solid and an aqueous phase, preferably water, are kneaded to obtain a mixture.

[0132] According to one embodiment, the organic solvent, the solid organic peroxide and the aqueous phase, preferably water, can be kneaded at the same time.

[0133] According to one embodiment, the solid organic peroxide and the aqueous phase, preferably water, are first mixed and then the organic solvent is added in order to be kneaded. Alternatively, the solid organic peroxide and at least a part of the aqueous phase are already mixed with each other before step a).

[0134] According to one embodiment, the organic solvent and the aqueous phase, preferably water, are first mixed and then the solid organic peroxide is added in order to be kneaded.

[0135] According to a particular embodiment, the organic solvent is added to the aqueous phase to be mixed and then the solid organic peroxide is added to be kneaded.

[0136] According to a preferred embodiment, the aqueous phase may comprise sodium tripolyphosphate in order to prevent the mixture from sticking to the surfaces of the apparatus, in particular to the surfaces of the reactor involved during the manufacture of said mixture.

[0137] According to a preferred embodiment, the aqueous phase may further comprise at least one pH modifying agent which may be chosen from alkaline agents, in particular chosen from organic or mineral alkaline agents, acidifying agents, in particular chosen from organic or mineral acids such as phosphoric acid, lactic acid or citric acid, and mixtures thereof.

[0138] Preferably, the aqueous phase may contain at least one pH modifying agent chosen from the group consisting of mineral alkaline agents, such as sodium hydroxide (NaOH), mineral acids and mixtures thereof.

[0139] more preferably, the aqueous phase may contain a combination of at least one alkaline agent and at least one acidifying agent, in particular a combination of at least one mineral alkaline agent and at least one mineral acid.

[0140] According to a preferable embodiment, a combination of at least one mineral alkaline agent and at least one mineral acid can advantageously neutralize the pH of a mixture comprising at least one organic solvent chosen from the group consisting of C4-Ci2 alkyl esters of dicarboxylic acids and cyclohexanedicarboxylates, in particular diisononyl 1,2-cyclohexanedicarboxylate.

[0141] The pH of the mixture in step a) may be less than 9, preferably less than 8, more preferably slightly less than 8.

[0142] According to a preferred embodiment, the pH of the mixture in step a) ranges from 6 to 8, preferably from 7 to 8, even more preferably from 7.5 to less than 8.

[0143] Preferably, the aqueous phase comprises at least one pH modifying agent such as as defined above and sodium tripolyphosphate.

[0144] Preferably, the organic solvent and an aqueous phase, in particular containing at least one pH modifying agent and sodium tripolyphosphate, are first mixed and then the solid organic peroxide is added in order to be kneaded.

[0145] According to one embodiment, step a) can be carried out up to a temperature strictly lower than the self-accelerated decomposition temperature TDAA of said solid organic peroxide, preferably at least 10°C lower, more preferably at least 20°C lower than this.

[0146] According to a preferred embodiment, step a) can be carried out at a temperature ranging from 30°C to 65°C, preferably at a temperature ranging from 40°C to 60°C, more preferably at a temperature ranging from 45°C to 55°C, even more preferably at a temperature ranging from 50°C to 55°C.

[0147] According to a preferred embodiment, at least one organic solvent as defined above and an aqueous phase as defined above are mixed and then heated to a temperature strictly lower than the self-accelerating decomposition temperature TDAA of said solid organic peroxide, in particular at a temperature ranging from 30°C to 65°C, more particularly ranging from 40°C to 60°C, even more particularly from 45°C to 55°C, preferably even more at a temperature ranging from 50°C to 55°C, before adding said solid organic peroxide.

[0148] According to this preferred embodiment, the resulting mixture can be further heated to the temperature defined above.

[0149] As indicated above, the method further comprises a step b) of reducing the aqueous phase of said mixture, preferably in one or more steps, to obtain in particular a composition which may be in a paste form. In other words, at least a part of the aqueous phase, preferably the major part of the aqueous phase, is separated from said mixture. Some water may remain in the mixture, preferably less than 10% by weight of water remains in said mixture after step b).

[0150] The concentration of the aqueous phase may therefore be reduced by separating said aqueous phase from said mixture in one or more steps, preferably in one step.

[0151] In particular, the aqueous phase may be separated from said mixture in one or more steps by filtration, distillation or other available methods in order to obtain a composition comprising said solid organic peroxide.

[0152] According to a preferred embodiment, the aqueous phase, preferably water, is separated from said mixture in one or more steps by filtration in order to obtain a composition comprising said solid organic peroxide.

[0153] In particular, after being kneaded in step a), the mixture is cooled, preferably at a temperature which may range from 4 to 50°C, and then the aqueous phase, preferably water, is separated from said mixture in one or more stages by filtration, preferably for a period of at least 24 hours.

[0154] The composition resulting from the separation in step b) is consequently depleted in aqueous phase compared to the mixture provided in step a), which means that the concentration of the aqueous phase in the resulting composition is lower than that of the mixture produced in step a).

[0155] Preferably, the composition resulting from the separation described above is in particular in the form of a paste.

[0156] For the purposes of the present invention, the terms "pasty composition" or "composition in a paste form" mean that the composition resulting from the separation step has the rheological behavior of a viscous liquid.

[0157] The pasty composition may comprise an aqueous phase, preferably water, in a concentration ranging from 3% to 10% by weight, preferably in a concentration ranging from 4% to 7% by weight, more preferably in a concentration ranging from 5% to 7% by weight relative to the total weight of the pasty composition. The pasty composition may comprise at least said solid organic peroxide as defined above in a concentration ranging from 20% to 75% by weight, preferably in a concentration ranging from 40% to 75% by weight, more preferably in a concentration ranging from 60% to 70% by weight relative to the total weight of the pasty composition.

[0158] The pasty composition may further comprise at least said organic solvent in a content ranging from 5 to 50% by weight, preferably in a content ranging from 10 to 40%, more preferably in a concentration ranging from 15% to 30% by weight relative to the total weight of the pasty composition.

[0159] Preferably, the pasty composition comprises:

[0160] - at least said organic peroxide as defined previously in one concentration ranging from 20% to 75% by weight, preferably in a concentration ranging from 40% to 75% by weight, more preferably in a concentration ranging from 60% to 70% by weight relative to the total weight of the pasty composition,

[0161] - an aqueous phase, preferably water, in a concentration ranging from 3% to 10% by weight, preferably in a concentration ranging from 4% to 7% by weight, more preferably in a concentration ranging from 5% to 7% by weight relative to the total weight of the pasty composition and

[0162] - at least said organic solvent in a content ranging from 5% to 50% by weight, of preferably in a concentration ranging from 10% to 40% by weight, more preferably in a concentration ranging from 15% to 30% by weight relative to the total weight of the pasty composition.

[0163] As defined previously, the method according to the present invention further comprises a step c) consisting of mixing at least one inert filler, preferably two inert fillers, as defined previously, with the composition which follows in order to obtain a powder composition comprising said solid organic peroxide.

[0164] Preferably, the inert filler is selected from the combinations of at least one hydrophobic silica sold under the trade name SIPERNAT® D17 and at least one hydrophilic silica sold under the trade name SIPERNAT® 2200.

[0165] According to a preferred embodiment, the method may comprise the addition of a hydrophobic silica, such as silicas sold under the trade name SIPERNAT® D17, in one step and the addition of a hydrophilic silica, such as silicas sold under the trade name SIPERNAT® 2200, in two successive steps in said pasty composition.

[0166] According to a preferred embodiment, the method may comprise:

[0167] i) the addition to said pasty composition of:

[0168] - a hydrophobic silica, such as silicas sold under the name com SIPERNAT® D17 commercial,

[0169] - a partial quantity of hydrophilic silica, such as silicas sold under the name commercial name SIPERNAT® 2200,

[0170] ii) mixing the mixture obtained, in particular for a period of approximately 30 minutes,

[0171] iii) adding the residual amount of said hydrophilic silica to said pasty composition.

[0172] Preferably, at least one inert filler, preferably at least two inert fillers, are mixed with the composition resulting from step b), in particular the pasty composition, in a mixer, in particular a mixer with ejection blades, usually called a paddle mixer.

[0173] According to a preferred embodiment, the method may further comprise a step d) consisting of adding at least one powder having a crystalline structure and a melting temperature ranging from 30°C to 80°C as defined above into the composition, preferably into the composition resulting from step b), preferably the pasty composition. Preferably, step d) is carried out before step c), at the same time as it or after it and preferably it is even carried out after step c).

[0174] The method may further comprise a step of limiting the particle size distribution of the obtained powder composition comprising said organic peroxide, in particular by means of mechanical sieving on a metal sieve.

[0175] The particle size and size distribution of the composition can be measured by dry sieving, carried out by a VE 1000 sieve shaker from RETSCH, operating for 20 minutes at an oscillation angle of 1.5 mm.

[0176] The particle size of the composition is advantageously greater than 73 pm, preferably greater than 100 pm.

[0177] The particle size of the composition is advantageously less than 1000 μm, preferably less than 800 μm.

[0178] The method according to the present invention can lead to a powder composition as defined above.

[0179] Preferably, the process according to the present invention can lead to a powder composition comprising an aqueous phase in a concentration of up to 10% by weight, preferably from 3 to 10% by weight, preferably from 4 to 6% by weight, relative to the total weight of the powder composition.

[0180] Preferably, the process according to the present invention can lead to a powder composition comprising at least one solid organic peroxide in a content ranging from 20 to 60% by weight, preferably from 30 to 55% by weight, more preferably from 40 to 55% by weight relative to the total weight of the powder composition.

[0181] The process according to the present invention can lead to a powder composition comprising at least one inert filler, preferably two inert fillers, in a total content ranging from 8% to 35% by weight relative to the total weight of the powder composition.

[0182] As detailed above, the present invention also relates to a powder composition which can be obtained from the process as defined above. Use of the composition

[0183] The present invention further relates to the use of said powder composition as a polymerization initiator for acrylic resins or unsaturated polyester resins, preferably acrylic resins, or as a polymer modifier, for example as a crosslinking agent, grafting agent or polymer rheology modifier.

[0184] Preferably, the invention relates to the use of said powder composition as a polymerization initiator for acrylic resins or unsaturated polyester resins, in particular acrylic resins.

[0185] Another object of the invention is the use of said composition for road marking, chemical anchoring, waterproofing and floor covering applications, preferably road marking. Examples: Example 1:

[0186] The purpose of the following examples (Examples 1 and 2) is to study the flow behavior and agglomeration properties of a commercial powdered peroxide formulation comprising 50% by weight of dibenzoyl peroxide to which water has been added. Such a commercial peroxide formulation does not contain any organic solvent.

[0187] a. Protocol

[0188] A commercial peroxide formulation in powder form sold under the name BP50 FT1 by United Initiators containing 50% by weight of dibenzoyl peroxide and 1% by weight of water was provided.

[0189] 0.15 grams of water is added to 10 grams of BP50 FT1. The components are then stirred with a spatula for 10 minutes at a temperature of 23°C to promote mixing so that the final peroxide formulation ends up with a water content of 2.5% by weight relative to the total weight of the peroxide formulation.

[0190] The resulting peroxide formulation is then kept in a closed beaker (sealed with Parafilm) at a temperature of 23°C.

[0191] The consistency of this formulation is examined after 2 hours, 1 day, 3 days and 1 week and compared to that of the commercial peroxide formulation BP50 FT1 without the addition of water.

[0192] After each control point, the peroxide formulation is stirred with a spatula to observe the result and then re-enclosed and left at a temperature of 23°C.

[0193] b. Results

[0194] The findings are summarized in Table 1:

[0195] [Tableauxl] Time / After Visual observation T = after 2 hours Unsatisfactory flow behavior, lumps remaining in the peroxide formulation leading to agglomeration T = after 1 day Flow behavior has improved but is not as good as that of BP50 FT1 without added water. Lumps are still visible. T = after 3 days Unsatisfactory agglomeration, lumps are still visible. T = after 1 week Unsatisfactory agglomeration, lumps are still visible.

[0196] This means that a peroxide formulation containing 50% by weight of dibenzoyl peroxide and 2.5% by weight of water does not have satisfactory flow behavior and agglomeration properties. This is because this formulation is an agglomerating powder composition which can flow less than the same formulation to which water has not been added. Example 2:

[0197] a. Protocol

[0198] After 1 week, an additional 0.27 grams of water is added to the previously studied organic peroxide formulation (containing BP 50 FT1 and 2.5% by weight of water) to increase the total water content to 5% by weight.

[0199] After mixing to achieve the best possible homogeneity, a significant deterioration in the flowability properties of the peroxide formulation can be observed.

[0200] In particular, it can be noted that water remains on the surface of the grains, which makes the powder appear wet. The grains end up sticking to the glass and form lumps.

[0201] In the same manner as in Example 1, the consistency of such a formulation is again observed over a period of one week following the same control points (i.e. after 2 hours, after 1 day, after 3 days and after 1 week).

[0202] The visual findings are summarized in Table 2:

[0203] [Tables2] Time / after Visual observation T = after 2 hours Unsatisfactory flow behavior, moisture and lumps remain which lead to agglomeration T = after 1 day Moisture and lumps remain which lead to agglomeration T = after 3 days Moisture and lumps remain which lead to agglomeration T = after 1 week Moisture and lumps remain which lead to agglomeration

[0204] This means that such a peroxide formulation containing 5% by weight of water does not exhibit satisfactory flow behavior and agglomeration properties. Indeed, this formulation is an agglomerating powder composition which may flow less than the same formulation to which water has not been added.

[0205] Therefore, the above-mentioned examples show that powdered peroxide formulations containing no organic solvent and having a water concentration of 2.5% or 5% by weight, based on the total weight of the formulation, lack flowability and have agglomeration problems. Example 3

[0206] a. Protocol

[0207] In a reactor, sodium hydroxide (0.5 g) and sodium tripolyphosphate (0.5 g) are added to 1000 g of water. 170 grams of an organic solvent sold under the trade name Hexamoll Dinch is added and the whole is then mixed to produce a thick suspension.

[0208] The thick suspension is heated to a temperature of 55°C before adding 636 grams of a commercial peroxide formulation sold under the name Luperox A75 (peroxide formulation comprising 75% by weight of dibenzoyl peroxide and 25% by weight of water). The resulting mixture is then kneaded at this temperature.

[0209] The mixture is then cooled with ice and filtered for 24 hours in order to separate the aqueous phase present in said mixture to produce an intermediate product having a pasty form.

[0210] The intermediate product obtained comprises 67.8% by weight of dibenzoyl peroxide.

[0211] 200 grams of the intermediate product obtained are first introduced into a mixer with ejector blades, generally called a paddle mixer.

[0212] One or two inert fillers in the proportions given in Table 3 are then introduced into the mixer and the whole is then mixed for approximately 30 minutes.

[0213] Stearic acid may then be added depending on the composition.

[0214] The compositions are obtained according to the ingredients described in Table 3 below.

[0215] [Tables3] Al A2 A3 A4 A5 Intermediate product containing benzoyl peroxide (g) 200 200 200 200 200 Sipemat® 2200(g) 51.2 53.2 47.5 - 25.8 Sipemat® D17 - 18 23.7 80.2 25 Stearic acid (g) - - - 30

[0216] Each composition obtained comprises the following content of dibenzoyl peroxide relative to the total weight of the formulation:

[0217] [Tables4] Al A2 A3 A4 A5 % by weight of benzoyl peroxide in the final composition 54 50 50 48.4 48.3

[0218] b. Results

[0219] The compositions detailed in Table 3 are powder compositions which visually may flow.

[0220] Flowability

[0221] The versatility (flowability) of such compositions is determined by carrying out a Pfrengle test, according to DIN 53 916.

[0222] 150 ml of each sample are poured into a funnel whose outlet opening was previously closed.

[0223] Then the opening is cleared so that the powder flows out, while slowly stirring with the support plate. After two minutes of rest, the height of the powder cone is measured using the measuring bar and read on the scale. The thickness of the base plate (25 mm) must be subtracted from the measured height of the powder cone.

[0224] The result is the height of the powder cone in cm, minus 25 mm from the base disc.

[0225] The results are given in Table 5:

[0226] [Tables5] Al A2 A3 A4 A5 Flowability, visually Good Very good Very good Good Good Flowability, Pfrengle test (cm) 2.5 2.7 2.6 2.9 2.9-2.7

[0227] During the flowability test, it can be seen that the powder compositions have the ability to flow dropwise by themselves without a mixing medium.

[0228] Dust formation

[0229] The compositions generate little or no dust.

[0230] It can also be noted that composition A5 is less dusty than compositions A1-A4 thanks to the presence of stearic acid.

Claims

Claims

1. Composition in powder form comprising: - at least one solid organic peroxide, - at least two inert fillers, - at least one organic solvent and - an aqueous phase, preferably water.

2. A composition according to claim 1, characterized in that the solid organic peroxide is selected from the group consisting of solid diacyl peroxides, solid peroxydicarbonates, solid ketone peroxides, solid peroxyesters, solid hydroperoxides, solid dialkyl peroxides and mixtures thereof, preferably selected from the group consisting of solid diacyl peroxides, solid peroxydicarbonates and mixtures thereof, more preferably selected from the group consisting of solid diacyl peroxides.

3. A composition according to claim 1 or claim 2, wherein the inert filler is soluble in an acrylic and / or polyester resin at a temperature ranging from 15°C to 27°C, preferably from 20°C to 25°C.

4. A composition according to any preceding claim, wherein the inert filler is selected from the group consisting of silicas, preferably selected from the group consisting of silicas obtainable from a precipitation process.

5. A composition according to any preceding claim, wherein the inert filler is selected from the group consisting of hydrophobic silicas, hydrophilic silicas and mixtures thereof, more preferably selected from combinations of at least one hydrophobic silica and at least one hydrophilic silica.

6. A composition according to any preceding claim, wherein the organic solvent is selected from the group consisting of dibasic acid alkyl esters, cyclohexanedicarboxylates, esters based on glycols, polyglycols and polyols and mixtures thereof, preferably from the group consisting of cyclohexanedicarboxylates and dibasic acid alkyl esters and mixtures thereof.

7. Composition according to any one of the preceding claims, comprising at least one crystalline powder having a temperature of melting ranging from 30°C to 80°C, especially a solid fatty acid.

8. Composition according to any one of the preceding claims, characterized in that the total quantity of aqueous phase present in said composition ranges from 3% to 10% by weight, preferably from 4% to 7% by weight, more preferably from 4% to 6% by weight relative to the total weight of the composition.

9. A process for the preparation of a composition in powder form comprising the steps of: a) mixing at least one organic solvent as defined in either of Claim 1 or Claim 6, at least one solid organic peroxide as defined in either of Claim 1 or Claim 2 and an aqueous phase, preferably water, b) reducing the aqueous phase of said mixture, c) mixing at least one inert filler, preferably at least two inert fillers, as defined in any one of Claims 1 and 3 to 5, with the resulting composition to obtain a powder composition comprising said solid organic peroxide.

10. A method according to claim 9, further comprising a step d) of adding at least one crystalline powder having a melting temperature ranging from 30°C to 80°C, in particular a solid fatty acid, into the composition, in particular into the composition resulting from step b).

11. 11. Use of the composition as defined in any one of claims 1 to 8 as a polymerization initiator for acrylic resins or unsaturated polyester resins, preferably acrylic resins, or as a polymer modifier, for example as a crosslinking agent, grafting agent or polymer rheology modifier, preferably as a polymerization initiator for acrylic resins or unsaturated polyester resins.

12. 12. Use of the compositions as defined in any one of claims 1 to 8 for road marking, chemical anchoring, waterproofing and / or floor covering applications.