Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F10/02—Ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0025—Crosslinking or vulcanising agents; including accelerators
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/14—Peroxides
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/22—Compounds containing nitrogen bound to another nitrogen atom
  • C08K5/23—Azo-compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/34—Heterocyclic compounds having nitrogen in the ring
  • C08K5/3412—Heterocyclic compounds having nitrogen in the ring having one nitrogen atom in the ring
  • C08K5/3415—Five-membered rings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/06—Polyethene
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
  • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
  • H01B3/441—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from alkenes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/10—Esters; Ether-esters
  • C08K5/101—Esters; Ether-esters of monocarboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2312/00—Crosslinking

Definitions

• the subject of the invention is the impregnation of polymer granules (composition) with a mixture of free radical initiator previously solubilized in a crosslinking promoter (primary mixture).
• the invention also relates to a process for producing crosslinked polymer previously impregnated with a mixture of free radical initiator solubilized in a crosslinking promoter.
• the free radical initiator is selected from organic peroxides, azo compounds and mixtures thereof.
• the initiators of free radicals thermally decompose, producing free radicals. They make it possible to give to many polymers, and more particularly to rubbers and polyolefms, excellent mechanical, thermal and chemical characteristics, thanks to the formation of covalent bonds between the polymer chains. This operation is called crosslinking.
• a crosslinking bond is a carbon-carbon bond between the adjacent chains of the polymer.
• Premature crosslinking reactions reduce the viscoelastic properties of the polymer, so that the material can no longer be suitably transformed and induce the formation of gel particles leading to inhomogeneity of the material.
• the free radical initiator should be mixed with the polymer at a temperature not exceeding the melting point of the polymer.
• This method of impregnating the free radical initiator into polymer granules is often the limiting step in the production of these polymer granules. Indeed, it is often necessary for this step to take place at a certain temperature and for a certain time in order to guarantee homogeneous impregnation of these granules. It is therefore imperative to be able to minimize this impregnation time.
• the initiator of free radicals at room temperature When the initiator of free radicals at room temperature is in the solid state, it therefore needs to be generally heated above its melting temperature to be incorporated in its liquid form to a polymeric matrix.
• the polymer granules Before being converted into the finished product either by extrusion or injection processes, the polymer granules must be able to be stored for several months without the crosslinking agent desorbing said granules. In order to avoid an inhomogeneity in the composition of the product, the desorption time must be as long as possible.
• the amount of free radical initiator, generally organic peroxides, necessary for the crosslinking of polymers is sufficiently high to create problems of significant generation of VOC (Volatile Organic Compound). Indeed, the crosslinking reactions tend to release volatile products from the decomposition of organic peroxides. Depending on the desired performance, a long degassing process is then necessary after the production of the finished products to eliminate some of these volatile products, and more particularly the methane in the case of electrical wiring type applications. State of the art
• US 3455752 discloses a mixture of polyethylene and dicumyl peroxide previously melted for the production of cross-linked polyethylene for electric cable coating.
• Oxidation reactions of organic peroxides can be inhibited by the presence of antioxidant.
• US 4101512 discloses the dissolution of an antioxidant in previously melted dicumyl peroxide. This mixture is then added to polyethylene pellets in electrical cable coating applications.
• US 7160958 discloses a mixture of organic peroxide with an absorption promoter additive in polymer particles at a temperature above the melting point of the organic peroxide and below the glass transition temperature of the polymer.
• the method described in US 7160958 seems to allow an increase in the rate of absorption of the peroxide in the polymer granules, but only in the first minutes of the impregnation, while it is known that the complete impregnation of the polymer is usually reached in several hours, to allow the peroxide to spread evenly inside the polyethylene pellets.
• dicumyl peroxide is added in the solid state in the polyethylene pellets.
• this implementation procedure is no longer used because of the risk of poor absorption that this procedure may entail.
• thermoplastic composition characterized in that it comprises:
• component (a) of component (b) being 100 parts by weight
• component (B) an olefinic plastic material; the sum of component (b) and component (B) being not less than 5 parts by weight per 100 parts by weight of the final composition.
• the weight ratio organic peroxide crosslinking promoter is much lower than 1 (of the order of 0.6), which fundamentally changes the physicochemical properties of the composition.
• the mixture of free radical initiator and crosslinking promoter is either liquid at ambient temperature or liquid at the impregnation temperature of the polyethylene, that is to say at a temperature slightly above room temperature;
• the impregnation time (of the free radical initiator in the polyethylene) is markedly reduced, which can in certain cases be halved compared with the use of non-solubilized free radical initiator in the crosslinking promoter;
• the mixture of free radical initiator and crosslinking promoter does not desorb the polymer, or with a very significantly lower kinetics compared to the methods of the state of the art;
• the release of volatile products is also significantly reduced, as is the amount of free radical initiators, this reduction can reach 40%, compared with the use of organic peroxide not solubilized beforehand with the crosslinking promoter .
• the dissolution of the free radical initiator in a crosslinking promoter in order to form the primary mixture is a preliminary operation carried out in a variable time depending on the chosen peroxide / promoter pair and the mixing temperature, which may range from a few minutes to many hours.
• the dissolution and homogenization of the primary mixture is an essential step to ensure the best results of impregnation of the primary mixture in the polymer.
• the present invention relates to a primary mixture for the crosslinking of polyethylene, comprising at least one free radical initiator chosen from organic peroxides, azo compounds or mixtures thereof, characterized in that it consists of said free radical initiator and at least one free radical initiator.
• crosslinking promoter chosen from cycloalkanes having 5 to 7 carbon atoms, substituted with 1 to 3 vinyl, allyl or isopropenyl groups, aromatic compounds substituted with 1 to 3 vinyl, allyl or isopropenyl groups, monomers based on methacrylate, of acrylate, maleimide, multi-substituted and in that the weight ratio of free radical initiator to crosslinking promoter is greater than or equal to 1, preferably between 1.5 and 4.
• the crosslinking promoter is trivinylcycloalkane and / or divinylbenzene;
• the free radical initiator is dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane or di- [(t-butyl-peroxy) isopropyl] benzene or a mixtures of these initiators;
• the primary mixture is in liquid form at room temperature, at least for a temperature between 10 ° C and 50 ° C at ambient pressure (1 bar).
• the invention also relates to a composition for the crosslinking of polyethylene, comprising polyethylene, preferably low density polyethylene, characterized in that it further comprises a primary mixture as described above.
• This composition is understood here as all the components (free radical initiator, crosslinking promoter and polyethylene) before the polyethylene crosslinks.
• the composition according to the invention further comprises at least one UV protection agent, an implementing agent, an anti-fogging agent, an anti-blocking agent, a coupling agent, a pigment, a colorant, a plasticizer, a plasticizer, a flame retardant and / or a crosslinking retarder.
• the invention also relates to a process for producing crosslinked polyethylene, comprising a final step of crosslinking polyethylene, in which:
• a free radical initiator is chosen from organic peroxides, azo compounds or their mixtures, preferably said initiator is chosen from dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane or diisocyanate; [(t-butylperoxy) isopropyl] benzene or a mixture of these initiators, and wherein
• At least one crosslinking promoter is chosen from cycloalkanes having 5 to 7 carbon atoms, substituted with 1 to 3 vinyl, allyl or isopropenyl groups, aromatic compounds substituted with 1 to 3 vinyl, allyl or isopropenyl groups, the monomers with base of methacrylate, acrylate, maleimide, multi-substituted, preferably said promoter is chosen from trivinylcycloalkane and / or divinylbenzene, characterized in that initially a dilution step of the above-mentioned free radical initiator is carried out with the aforesaid promoter crosslinking, then impregnating the primary mixture thus formed (as described above), in liquid form, with polyethylene.
• the crosslinking promoter is present in liquid form at ambient temperature and pressure, that is to say for a temperature of between 10 ° C. and 50 ° C. C at a pressure of 1 bar.
• the crosslinking step is carried out by extrusion or injection.
• the present invention relates to the use of the primary mixture as described above or the aforementioned composition for the production of cables, in particular for the transport of fluid or electric current.
• the following description is given solely for illustrative and not limiting. Detailed description of the invention
• the present invention is for polymer crosslinking.
• the polymer according to the invention may be any type of polymer that may be crosslinked by organic peroxides, the present invention being more particularly intended for the crosslinking of polyethylene.
• polyethylene high density polyethylenes (PE-HD), low density polyethylenes (PE-LD), linear low density polyethylenes (LLDPE), very low density polyethylenes (VLDPE), are included.
• PE-HD high density polyethylenes
• PE-LD low density polyethylenes
• LLDPE linear low density polyethylenes
• VLDPE very low density polyethylenes
• polyethylenes obtained by metallocene catalysis copolymers of ethylene with one or more comonomers, such as ⁇ ethylene-propylene-diene terpolymers (EPDM), ethylene-propylene copolymers (EPM), ethylene-acetate copolymers vinyl (EVA), ethylene-alkyl acrylate copolymers (EMA, EEA, EBA), copolymers of ethylene- (alpha-omega) alkadienes.
• EPDM ⁇ ethylene-propylene-diene terpolymers
• EPM ethylene-propylene copolymers
• EVA ethylene
• the other polymers concerned by the present invention are hydrogenated butadiene-acrylonitrile copolymers (HNBR), butadiene-acrylonitrile copolymers (NBR), fluoroelastomers (FKM) and polybutadienes (PBU).
• HNBR hydrogenated butadiene-acrylonitrile copolymers
• NBR butadiene-acrylonitrile copolymers
• FKM fluoroelastomers
• PBU polybutadienes
• Polymers such as high density polyethylenes, low density polyethylenes and ethylene-propylene copolymers are particularly preferred. Nevertheless, in the specific context of polyethylene crosslinking and for this invention, the low density polyethylenes will be selected preferentially.
• free radical initiator it is understood organic peroxides, and more particularly the organic peroxides used as crosslinking agents such as dialkyl peroxides, diperoxyketals and certain monoperoxycarbonates, to which the azo compounds can be added.
• the free radical initiator of the primary mixture according to the invention may consist of one or more organic peroxides and / or azo compounds.
• dialkyl peroxides the preferred initiators are: dicumyl peroxide (marketed Luperox ® DC or Luperox ® DCP), di-t-butyl (Luperox ® DI), peroxide t-butyl cumyl (Luperox ® 801), the 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (Luperox ® 101), 2,5-dimethyl-2,5-di (t-amyl peroxy) hexane, 2,5- dimethyl-2,5-di (t-butylperoxy) hexyne-3 (Luperox ® 130), 2,5-dimethyl-2,5-di (t-amyl peroxy) hexyne-3, a, a'-di - [( t-butylperoxy) isopropyl] benzene (Luperox ® F), ⁇ , ⁇ '-
• Some monoperoxycarbonates such as 00-tert-butyl-0- (2-ethylhexyl) monoperoxycarbonate (Luperox TBEC ®), OO-tert-butyl-O-isopropyl monoperoxycarbonate (Luperox ® TBIC) and OO-tert-amyl-O-2 hexyl monoperoxycarbonate (Luperox ® TAEC) are also used.
• the preferred initiator is benzoyl peroxide (Luperox ® A75).
• the preferred initiators are: l, l-di- (t-butylperoxy) -3,3,5-trimethylcyclohexane (Luperox ® 231), 4,4-di- (t-amylperoxy) valerate, n-butyl (Luperox ® 230), 3,3-di- (t-butylperoxy) butyrate (Luperox ® 233), 2,2-di- (t-amylperoxy) propane, 3,6,6,9,9 3-pentamethyl-3-ethoxycarbonylmethyl-1,2,4,5-tetraoxacyclononane, 3,3,5,7,7-pentamethyl-1,2,4-trioxepane, 4,4-bis (t-butylperoxy) valerate n-butyl 3,3-di (t-amyl peroxy) butyrate, l, l-di (t-butylperoxy) cyclo
• Azo compounds include, for example, 2,2'-azobis (2-acetoxypropane), azobisisobutyronitrile, azodicarbamide, 4,4'-azobis cyanopentanoic acid and 2,2'-azobisisobutyronitrile. azobismethylbutyronitrile.
• crosslinking promoter it is understood cycloalkanes having 5 to 7 carbon atoms, substituted with 1 to 3 vinyl groups, allyl or isopropenyl, aromatic compounds substituted with 1 to 3 vinyl groups, allyl or isopropenyl, the monomers based on methacrylate, acrylate, maleimide, multi-substituted.
• vinylcyclohexane divinylcyclohexane, trivinylcyclohexane, vinylcyclopentane, diisopropenylcyclohexane and triisopropenyl cyclohexane.
• Cyclohexane substituted with 1 to 3 vinyl or allyl groups is advantageously used, in particular trivinylcyclohexane.
• trivinylcyclohexane contains predominantly 1,2,4 trivylcyclohexane.
• multi-substituted aromatic type crosslinking promoter mention may be made of divinylbenzene, diisopropenylbenzene, alpha-methylstyrene, alpha-methylstyrene dimer and triallyl trimellitate.
• ethylene glycol dimethacrylate phenylene dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol 200 dimethacrylate, polyethylene glycol 400 dimethacrylate, 1,3- butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,12-dodecanediol dimethacrylate, 1,3-glycerol dimethacrylate, diurethane dimethacrylate and trimethylolpropane trimethacrylate.
• cross-linking promoter based on multi-substituted methacrylate is advantageously used, in particular ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate.
• multi-substituted acrylate crosslinking promoter mention may be made of bisphenol A epoxy diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol 600 diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate , neopentyl glycol ethoxylate diacrylate, butanediol diacrylate, hexanediol diacrylate, aliphatic urethane diacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxylate triacrylate, trimethylolpropane propoxylate triacrylate, glycerol propoxylate triacrylate, aliphatic urethane triacrylate, trimethylolpropane triacrylate and dipentaerythritol pentaacrylate.
• the nitrogen-containing crosslinking promoter mention may be made
• trivinylcyclohexane and divinylbenzene will be chosen preferentially as a crosslinking promoter.
• antioxidants mention may be made of those of the hydroquinone family, such as hydroquinone, hydroquinone di (P-hydroxyethyl) ether, hydroquinone monomethyl ether, mono-tert-butyl hydroquinone, ditertiobutylhydroquinone and the like.
• the present invention relates to a primary mixture comprising only two components, namely the free radical initiator and the crosslinking promoter. Once this primary mixture is made, it is intended to impregnate polyethylene.
• composition primary mixture according to the invention with polyethylene
• various components which may comprise UV protection agents; processing agents, whose function is to improve the final appearance during its implementation, such as fatty amides, stearic acid and its salts, ethylene bis-stearamide or fluoropolymers; anti-fogging agents; anti-blocking agents such as silica or talc; fillers such as calcium carbonate and nanofillers such as clays; coupling agents such as silanes; antistatic agents; nucleating agents; pigments; dyes; plasticizers; fluidifiers and flame retardant additives such as aluminum or magnesium hydroxides.
• UV protection agents processing agents, whose function is to improve the final appearance during its implementation, such as fatty amides, stearic acid and its salts, ethylene bis-stearamide or fluoropolymers
• anti-fogging agents such as silica or talc
• fillers such as calcium carbonate and nanofillers such as clays
• coupling agents such as silanes
• one or more crosslinking retarders may also be introduced after the production / manufacture of the primary mixture according to the invention, such as the antioxidant compounds of the family of hydroquinones and phenolic antioxidants.
• These additives are generally used in contents of between 10 ppm and 10,000 ppm by weight relative to the weight of the final polymer.
• Plasticizers, fluidifiers and flame retardant additives can reach amounts well above 10000 ppm.
• LDPE low density polyethylene
• LDPE low density polyethylene
• 1 L Schott bottle one liter
• 6 g of dicumyl peroxide preheated to 60 ° C was added to the LDPE, the closed container was placed on a roller mixer at 15 rpm at 60 ° C.
• 13 g of the LDPE-based component is taken from the bottle and placed in 20 ml of methanol to be mixed for 30 seconds with a wooden spatula and the mixture is filtered on sieves.
• the non-adsorbed peroxide is thus removed from the surface of the LDPE by methanol, the adsorbed peroxide remaining in the LDPE granules which are then dried on sieves under a suction hood and then analyzed using an RPA2000 type rheometer.
• Table No. 1 evolution of the densities and kinetics of crosslinking as a function of the impregnation time for dicumyl peroxide used alone.
• LDPE low density polyethylene
• a glass container ie for example a Schott bottle of 1 L.
• 7.2 g of a mixture containing 50% of peroxide of dicumyl and 50% of The pre-heated trivetylcyclohexane at 60 ° C was added to the LDPE, the closed container was placed on a roller mixer at a rate of 15 rpm at 60 ° C.
• 13 g of LDPE-based component is taken from the bottle and placed in 20 milliliters (ml) of methanol to be mixed for 30 seconds with a wooden spatula and the mixture is filtered on sieves.
• the non-adsorbed peroxide is thus removed from the surface of the LDPE by methanol, the adsorbed peroxide remaining in the LDPE granules which are then dried on sieves under a suction hood and then analyzed using an RPA2000 type rheometer.
• LDPE low density polyethylene
• the non-adsorbed peroxide is thus removed from the surface of the LDPE by methanol, the adsorbed peroxide remaining in the LDPE granules which are then dried on sieves under a suction hood and then analyzed using an RPA2000 type rheometer.
• Table n ° 3 evolution of the densities and kinetics of crosslinking as a function of the impregnation time for dicumyl peroxide previously mixed with trivinylcyclohexane in mass proportions 75% Peroxide -25% Trivinylcyclohexane.
• LDPE low density polyethylene
• the non-adsorbed peroxide is therefore removed from the surface of the LDPE by methanol, the adsorbed peroxide remaining in the LDPE granules which are then dried on sieves under a hood and then analyzed using an RPA2000 type rheometer.
• Table n ° 4 evolution of the densities and kinetics of crosslinking as a function of the impregnation time for dicumyl peroxide premixed with divinyl benzene in mass proportions 50% Peroxide -50% divinyl benzene.
• the graph No. 1 below shows the comparison of the crosslinking density values obtained with the rheometer of the RPA 2000 type between the 4 systems, that is to say the examples No. 1, No. 2 No. 3 and No. ° 4 described above.
• divinyl benzene also improves the absorption of dicumyl peroxide: the mixture containing this additive requires 3 hours to reach a crosslinking density of 16 dN.m. - Measurement of the desorption time
• LDPE low-density polyethylene
• a glass container more precisely for example a 1 L Schott-type bottle.
• 6 g of dicumyl peroxide preheated to 60 ° C. were added to the LDPE.
• closed container was placed on a roller mixer at a speed of 15 rpm at 60 ° C.
• the bottle is placed in an airtight container at a temperature of 5 ° C.
• 13 g of LDPE-based component are taken from the bottle and placed in 20 ml of methanol to be mixed for 30 seconds with a wooden spatula and then the mixture is filtered through a sieve. .
• the LDPE granules are thus freed of the peroxide which has desorbed.
• the granules are then dried on sieves under an extractor hood and then analyzed using an RPA2000 type rheometer.
• LDPE low density polyethylene
• the LDPE granules are thus freed from the peroxide which has desorbed, they are then dried on sieves under a suction hood and then analyzed using an RPA2000 type rheometer.
• the evolution of the crosslinking density is detailed in Table No. 6 below which shows that no desorption is detected the first five (5) days in the case of dicumyl peroxide used previously mixed with trivinylcyclohexane in mass proportions 50% Peroxide - 50% Trivinylcyclohexane.
• Table n ° 6 evolution of the densities and kinetics of crosslinking as a function of storage time at 5 ° C for dicumyl peroxide premixed with trivinylcyclohexane in mass proportions 50% Peroxide -50% Trivinylcyclohexane.
• LDPE low density polyethylene
• a glass container ie a 1 L Schott bottle.
• 7.2 g of a mixture containing 50% dicumyl peroxide and 50% previously heated trivinylcyclohexane at 60 ° C were added to the LDPE, the closed container was placed on a roller mixer at a rate of 15 rpm at 60 ° C.
• the bottle is placed in a container (adiabatic) at 5 ° C.
• 13 g of LDPE-based component are taken from the bottle and placed in 20 ml of methanol to be mixed for 30 seconds with a wooden spatula and then the mixture is filtered through a sieve.
• the LDPE granules are thus freed from the peroxide which has desorbed, they are then dried on sieves under a suction hood and then analyzed using an RPA2000 type rheometer.
• the evolution of the crosslinking density is detailed in Table No. 7 below which shows that no desorption is detected the first five (5) days in the case of dicumyl peroxide used previously mixed with trivinylcyclohexane in mass proportions 75% Peroxide - 25% Trivinylcyclohexane.
• Table n ° 7 evolution of the densities and kinetics of crosslinking as a function of storage time at 5 ° C for dicumyl peroxide premixed with trivinylcyclohexane in mass proportions 75% Peroxide - 25% Trivinylcyclohexane.
• the graph No. 2 below shows the comparison of the crosslinking density values obtained with the RPA 2000 rheometer between the 3 systems (examples No. 5, No. 6 and No. 7 presented above).
• the present invention makes it possible to significantly reduce the volatile products, and more particularly methane, which are mainly derived from the decomposition of the organic peroxide. Indeed, it has been shown that the present invention makes it possible to obtain acceptable levels of crosslinking by using up to 40% less organic peroxide, consequently the quantity of volatile products is also reduced, this reduction going as far as at 40%.

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