Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/06—Preparatory processes
  • C08G77/10—Equilibration processes
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  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/045—Polysiloxanes containing less than 25 silicon atoms
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  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/06—Preparatory processes
  • C08G77/08—Preparatory processes characterised by the catalysts used
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  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
  • C08J11/16—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with inorganic material
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  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
  • C08J11/18—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material
  • C08J11/20—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material by treatment with hydrocarbons or halogenated hydrocarbons
• • 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
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
  • C08J11/18—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material
  • C08J11/22—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material by treatment with organic oxygen-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes
  • C08L83/08—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/14—Polysiloxanes containing silicon bound to oxygen-containing groups
  • C08G77/16—Polysiloxanes containing silicon bound to oxygen-containing groups to hydroxy groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/20—Polysiloxanes containing silicon bound to unsaturated aliphatic groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/22—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen
  • C08G77/24—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen halogen-containing groups
• • 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
  • C08J2383/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen, or carbon only; Derivatives of such polymers
  • C08J2383/04—Polysiloxanes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/62—Plastics recycling; Rubber recycling

Definitions

• the present invention relates to cyclic organopolysiloxanes and more particularly to a process for preparing cyclic organopolysiloxanes by depolymerization of organopolysiloxanes in the presence of a catalytic system comprising an alkaline catalyst and a multidentate complexing agent.
• One of the recycling routes envisaged is the depolymerization of organopolysiloxanes to produce cyclic organopolysiloxanes (or cyclosiloxane).
• An objective of the present application is therefore to propose a process for depolymerizing organopolysiloxane efficiently and making it possible to obtain a good yield of cyclic organopolysiloxanes in particular D3, D4 and D5.
• Another objective of the present application is to provide a catalytic system for the implementation of this process.
• Yet another objective of the present application is to propose a simple catalytic system allowing good reaction kinetics compatible with industrialization of the process.
• the organopolysiloxane O of the invention can be any type of organopolysiloxane, in particular chosen from linear organopolysiloxanes, for example oils, or gums, or branched organopolysiloxanes.
• the organopolysiloxane O may in particular be an oil or a gum, and preferably has a dynamic viscosity of between 50 and 600,000 mPa.s at 25°C or a consistency of between 200 and 2000 expressed in tenths of a millimeter at 25°C. . All the viscosities discussed in this presentation correspond to a quantity of dynamic viscosity at 25°C called “Newtonian”, that is to say the dynamic viscosity which is measured, in a manner known per se, with a viscometer. Brookfield at a sufficiently low shear rate gradient that the measured viscosity is independent of the rate gradient.
• gum is used for organopolysiloxane compounds having viscosities typically greater than 600,000 mPa.s which corresponds to a molecular weight greater than 260,000 g/mole.
• the consistency or penetrability of a gum is determined at 25°C using a PNR12 type penetrometer or equivalent model allowing a cylindrical head to be applied to the sample under standardized conditions.
• organopolysiloxanes O may comprise one or more functional units such as:
• alkenyl in particular comprising from 2 to 6 carbon atoms, preferably vinyl;
• Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preference methyl;
• Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms carbon, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200;
• Alk represents an alkyl comprising from 1 to 5 carbon atoms
• - cyclic amine for example -(CH2) z -O-piperidine in which z represents an integer from 1 to 5, preferably 3, and the piperidine can be substituted in particular by one or more alkyl groups comprising from 1 to 3 carbon atoms , preferably methyl, preferably the substituted piperidine is a group
• the organopolysiloxanes O may comprise one or more functional units such as H, OH, alkenyl (preferably vinyl), aryl, cyclic amine, as defined above.
• the organopolysiloxanes O of the invention can be partially crosslinked.
• the organopolysiloxanes O of the invention may in particular be used organopolysiloxanes, having served for example as a heat transfer fluid, which should be recycled, the process of the invention thus making it possible to generate cyclic organopolysiloxanes OC which can then be directly used in industrial processes, particularly in new polymerization processes.
• the organopolysiloxanes O of the invention can be silicone oils in particular terminated with trimethylsilyl, dimethylhydroxysilyl or dimethylvinylsilyl units or else silicone gels.
• the organopolysiloxane may then contain other elements such as additives, pigments, etc., the inventors have shown that the presence of these other elements does not disturb the depolymerization reaction and the formation of cyclic organopolysiloxanes OC.
• the organopolysiloxane O of the invention comprises:
• R is as defined above
• R 1 identical or different, represents:
• a group (O-Alk) with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 atoms of carbon, preferably OCH 3 or OC2H5,
• a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200,
• Alk an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms;
• cyclic amine for example -(CH2) z -O-piperidine in which z represents an integer from 1 to 5, preferably 3, and the piperidine can be substituted in particular by one or more alkyl groups comprising from 1 to 3 carbon atoms , preferably methyl, preferably the substituted piperidine is a group
• R 1 identical or different, represents:
• cyclic amine for example -(CH2) z -O-piperidine in which z represents an integer from 1 to 5, preferably 3, and the piperidine can be substituted in particular by one or more alkyl groups comprising from 1 to 3 carbon atoms , preferably methyl, preferably substituted piperidine ⁇ r z NH r is a group;
• siloxyl unit “M” represents a siloxyl unit of formula YsSiOi/2
• siloxyl unit “D” represents a siloxyl unit of formula Y2SiO2/2,
• siloxyl unit “T” represents a siloxyl unit of formula YSiOs/2
• siloxyl unit “Q” represents a siloxyl unit of formula SiC>4/2, the symbols Y being R or R 1 .
• the organopolysiloxane O may optionally comprise a small quantity of T and Q units.
• the depolymerization process of the invention can be implemented on organopolysiloxanes O comprising long chains of successive D units.
• the organopolysiloxane O according to the invention comprises less than 20%, preferably less than 10%, even more preferably less than 5% and even more preferably less than 2% of T or Q units as defined above relative to the number of total siloxyl units of the organopolysiloxane O.
• the organopolysiloxane O of the invention is preferably chosen from the compounds of formula (I):
• R identical or different, represents:
• an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl;
• R 1 identical or different, represents:
• a group (O-Alk) with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 atoms of carbon, preferably OCH 3 or OC2H5,
• a group (O-Alk) x with Alk represents an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl, and x represents an integer between 2 and 200,
• Alk an amino group chosen from (Alk)-NH2 or (Alk)-NH-(Alk)-NH2, with Alk representing an alkyl comprising from 1 to 5 carbon atoms;
• cyclic amine for example -(CH2) z -O-piperidine in which z represents an integer from 1 to 5, preferably 3, and the piperidine can be substituted in particular by one or more alkyl groups comprising from 1 to 3 carbon atoms , preferably methyl, preferably the substituted piperidine is a group
• the presence of Si-H group in organopolysiloxane O can generate a release of dihydrogen. It may therefore be advantageous, in the device for implementing the process of the invention, in the case where the quantity of Si-H group is large, to provide a device for managing the release of dihydrogen.
• the quantity of Si-H group is preferably less than 20%, preferably less than 10%, preferably less than 5%, preferably less than 2% by weight per relative to the total weight of organopolysiloxane O.
• the organopolysiloxane O of the invention is a compound of formula (I) in which R 1 , identical or different, represents:
• cyclic amine for example -(CH2) z -O-piperidine in which z represents an integer from 1 to 5, preferably 3, and the piperidine can be substituted in particular by one or more alkyl groups comprising from 1 to 3 carbon atoms , preferably methyl, preferably substituted piperidine
• ⁇ z NH r is a group
• the organopolysiloxane O of the invention is a compound of formula (I) in which R 1 , identical or different, represents CH 3 , vinyl, H or OH.
• the organopolysiloxane O of the invention is a compound of formula (I) in which
• R identical or different, represents CH 3 or phenyl, preferably CH 3 ;
• R 1 identical or different, represents:
• cyclic amine for example -(CH2) z -O-piperidine in which z represents an integer from 1 to 5, preferably 3, and the piperidine can be substituted in particular by one or more alkyl groups comprising from 1 to 3 carbon atoms , preferably methyl, preferably the substituted piperidine is a group
• the organopolysiloxane O of the invention is a compound of formula (I) in which
• R identical or different, represents CH 3 or phenyl, preferably CH 3 ;
• R 1 identical or different, represents CH 3 , vinyl, H or OH.
• the process of the invention can be implemented with organopolysiloxanes O having a dynamic viscosity of between 3 and 20,000,000 mPa.s, preferably between 3 and 6,000,000 mPa.s, for example between 3 and 1,000,000 mPa.s, at 25°C.
• the process of the invention can be implemented with an organopolysiloxane O or a mixture of organopolysiloxanes O having a dynamic viscosity, of the organopolysiloxane O or of the mixture of organopolysiloxanes O, of between 3 and 1 000,000 mPa.s, preferably between 100 and 60,000 mPa.s, at 25°C.
• the organopolysiloxanes O can have variable viscosities to the extent that the viscosity of the mixture is as mentioned above. -above.
• the process of the invention can be implemented in the presence of a solvent.
• the solvent must be chosen from the solvents solubilizing the organopolysiloxane O.
• the solvent can be an alcohol or n-paraffins.
• the alcohol is chosen from fatty alcohols such as n-lauryl alcohol, n-myristyl alcohol, n-palmitic alcohol, n-stearyl alcohol, n-docosanol, or alcohols de Guerbet such as 2-octyl 1 - dodecanol, 2-decyl 1 -tetradecanol.
• fatty alcohols such as n-lauryl alcohol, n-myristyl alcohol, n-palmitic alcohol, n-stearyl alcohol, n-docosanol, or alcohols de Guerbet such as 2-octyl 1 - dodecanol, 2-decyl 1 -tetradecanol.
• the n-paraffins are chosen from the compounds C16H34, C Hss, C20H42, C22H46, or C24H 5 o- If a solvent is used in the process of the invention, the quantity of solvent added is preferably between 5 and 50% by weight, preferably between 10 and 20% by weight, relative to the weight of organopolysiloxane O.
• the use of a solvent will allow the implementation of the process of the invention with more viscous organopolysiloxanes O, for example having a viscosity of between 1,000,000 and 20,000,000,000 mPa.s at 25°C so that the mixture (organopolysiloxane O + solvent ) has a viscosity between 3 and
• the alkaline salt catalyst is an alkali metal salt comprising a metal M, the metal M being chosen from K, Na, Rb or Cs, preferably K, Rb, Cs.
• said alkali metal salt is chosen from silanolates, hydroxides, alkoxides and siliconates, preferably silanolates.
• silanolate a salt derived from a silanol group which is a functional group comprising at least one Si-OH group.
• Silanolates generally have a formula MOSi(R')s with M as defined above and R', identical or different, represents an alkyl group, linear or branched, comprising 1 to 6 carbon atoms, or an alkenyl group. comprising of
• R' identical or different, represents methyl or vinyl.
• alkoxide a compound of formula MOAlk, with M as defined above and Alk represents an alkyl, linear or branched, comprising from 1 to 22 carbon atoms, preferably from 1 to 15 carbon atoms, preferably from 1 with 12 carbon atoms.
• the alkaline catalyst of the invention is a catalyst of formula MX with
• M is chosen from K, Na, Rb, Cs, preferably K, Rb, Cs, preferably K;
• X is chosen from OSIR 4 2R 5 , OH, OALK, with Alk represents an alkyl, linear or branched comprising from 1 to 22 carbon atoms, preferably 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms , (OSi(R 3 )2) P -OSi(R 3 )2 with M as defined above and R 3 represents an alkyl group comprising from 1 to 6 carbon atoms, preferably methyl, and p represents a number integer between 1 and 20, preferably between 1 and 10, R 4 identical or different represents a linear or branched alkyl comprising from 1 to 6 carbon atoms, preferably methyl, R 5 represents a linear or branched alkyl comprising from 1 with 6 carbon atoms, preferably methyl , or a vinyl group, preferably 2-(OSi(Me)2) P -OSiMe 3 with p as defined above.
• Alk represents an alkyl, linear or branched comprising from 1 to 22 carbon atoms,
• M is chosen from K, Rb , Cs and between 1 and 20, preferably between 1 and 10, and O-tBu (tBu represents tert-butyl).
• the alkaline catalyst is KOSiMes.
• multidentate complexant means a complexant of the alkali metal of the alkaline salt catalyst, that is to say a complexant of K, Na, Rb or Cs, preferably a complexant of K, Rb or Cs.
• the multidentate complexing agents of the invention are chosen from crown ethers, cryptands which are diamine macroheterocycles and polyethylene glycols (PEG) terminated OH or OCH 3 , preferably terminated OCH 3 , preferably polyethylene glycols are polyethylene glycol dimethyl ether.
• PEGs are soluble in the reaction medium.
• the PEGs have a low molar mass in number (Mn), for example between 100 and 2000, preferably between 200 and 1000 g/mol.
• the molar mass in number (Mn) can be measured by any technique known to those skilled in the art and for example by steric exclusion chromatography (CES).
• the crown ethers comprise from 2 to 8 oxygen atoms.
• Crown ethers are cyclic oligomers of ethylene oxide comprising as repeating unit a group (CH 2 -CH 2 -O), these crown ethers can be substituted or 2 carbon atoms of a unit (CH2-CH2-O) can be fused with a hydrocarbon ring, notably cyclohexyl or phenyl.
• the multidentate complexing agents are chosen from:
• the alkaline salt is used in catalytic proportions, preferably in an amount of between 0.005 and 1.5% by weight relative to the weight of organopolysiloxane (O), preferably between 0.005 and 0.9%, more preferably between 0.01 and 0.8%.
• the alkaline salt/multidentate complexing molar ratio is between 1/100 and 100/1, preferably between 1/50 and 50/1, preferably between 1/25 and 25/1. 1, preferably between 1/10 and 10/1, preferably between 1/4 and 4/1, preferably between 1/2 and 2/1, preferably greater than or equal to 1, preferably between 1 and 2 , for example the ratio is equal to 1.
• the method of the invention is carried out at a temperature between 50 and 200°C, preferably between 60 and 180°C, preferably between 120 and 160°C.
• the method of the invention uses reactive distillation.
• reactive distillation consists of the combination of separation by distillation and a reaction.
• the device implementing reactive distillation therefore combines a reactor and a distillation system.
• Reactive distillation, and the method of the invention can be implemented continuously or discontinuously.
• Batch reactive distillation combines the advantages of reactive distillation and the batch process.
• the reaction mixture is charged into the reactor and the reaction products are distilled gradually.
• the reagents are introduced continuously.
• the method of the invention, and the reactive distillation is implemented continuously.
• the temperature is between 50 and 200°C, preferably between 60 and 180°C, preferably between 120 and 160°C.
• the pressure is between 0.01 and 50 mbar, preferably between 0.1 and 35 mbar, more preferably between 5 and 30 mbar.
• the pressure is between 0.01 and 50 mbar for a temperature between 50 and 200°C, preferably the pressure is between 5 and 30 mbar for a temperature between 120 and 160° vs.
• the method of the invention, and the reactive distillation is implemented batchwise.
• the temperature is between 50 and 200°C, preferably between 60 and 180°C, preferably between 120 and 160°C.
• the pressure is between 0.01 and 50 mbar, preferably between 0.1 and 35 mbar, more preferably between 5 and 30 mbar.
• the reaction and heating begin at atmospheric pressure then after 10 to 120 min, preferably 30 to 60 min after reaching the temperature, the reactive distillation begins at a pressure of between 0.01 and 50 mbar, preferably between 0.1 and 35 mbar, more preferably between 5 and 30 mbar.
• the method of the present invention can be implemented in the absence of solvent or in the presence of a solvent, particularly of the alcohol type.
• the alcohol is chosen from fatty alcohols such as n-lauryl alcohol, n-myristyl alcohol, n-palmitic alcohol, n-stearyl alcohol, n-docosanol, or alcohols of Guerbet such as 2- octyl 1 -dodecanol, 2-decyl 1 -tetradecanol.
• the solvent can also be chosen from the group of n-paraffins such as the compounds C16H34, C Hss, C20H42, C22H46, C24H 5 o- If a solvent is used in the process of the invention, the quantity of solvent added East preferably between 5 and 50% by weight, preferably between 10 and 20% by weight, relative to the weight of organopolysiloxane.
• the cyclic organopolysiloxanes OC (or cyclic organopolysiloxanes) obtained by the method of the invention are preferably compounds D3, D4 or D5.
• the cyclic organopolysiloxanes OC obtained are obtained as a mixture with more than 95% by weight of a mixture of compounds D3, D4 or D5, preferably from 95 to 99%, relative to the total weight of cyclic organopolysiloxanes OC produced.
• the majority compound obtained by the method of the invention is compound D4.
• the method of the invention allows a D4 yield of at least 80% by weight.
• the starting organopolysiloxane O may comprise functions described by the group R 1 described above.
• at least one of the methyl groups of compounds D3, D4 and/or D5 can be substituted by at least one of R 1 .
• these compounds preferably comprise less than 10%, preferably less than 5%, preferably less 2% and even more preferably less than 0.2% by weight of functions described by group R 1 as described above relative to the total weight of compounds D3, D4 and D5.
• the method of the invention preferably makes it possible to obtain a mass yield of cyclic organopolysiloxanes OC greater than 85%, preferably greater than 95% and which can go up to 99% by weight.
• the compounds D3, D4 and D5 can be separated in particular by distillation, for example by distillation with numerous theoretical plates.
• the compounds D3, D4 and D5 obtained by the process of the invention can be directly used in other industrial processes to be polymerized and to manufacture new oils and gums.
• the present invention also relates to the use of a catalytic system comprising an alkaline salt selected from salts of K, Na, Rb or Cs, and a multidentate complexing agent, for the depolymerization of organopolysiloxanes O to produce cyclic organopolysiloxanes OC.
• the alkaline salt for the aforementioned use is as defined above.
• the multidentate complexing agent for the aforementioned use is as defined above.
• the multidentate complexing agents used for the depolymerization of organopolysiloxanes O are chosen from crown ethers, cryptands which are diamine macroheterocycles and polyethylene glycols (PEG) terminated OH or OCH 3 , preferably terminated OCH 3 , preferably polyethylene glycols are polyethylene glycol dimethyl ether.
• PEGs are soluble in the reaction medium.
• the PEGs have a low molar mass in number (Mn), for example between 100 and 2000, preferably between 200 and 1000 g/mol.
• the crown ethers comprise from 2 to 8 oxygen atoms.
• Crown ethers are cyclic oligomers of ethylene oxide comprising as a repeating unit a group (CH2-CH2-O), these crown ethers can be substituted or 2 carbon atoms of a unit (CH2-CH2-O) can be fused with a hydrocarbon ring, notably cyclohexyl or phenyl.
• the multidentate complexing agents used for the depolymerization of organopolysiloxanes O are chosen from:
• the alkaline salt used for the depolymerization of organopolysiloxanes O is used in catalytic proportions, preferably in an amount of between 0.005 and 1.5% by weight relative to the weight of organopolysiloxane (O), preferably between 0.005 and 0.9%, more preferably between 0.01 and 0.8%.
• the alkaline salt/multidentate complexing molar ratio is between 1/100 and 100/1, preferably between 1/50 and 50/1, preferably between 1/25 and 25 /1, preferably between 1/10 and 10/1, preferably between 1/4 and 4/1, preferably between 1/2 and 2/1, preferably greater than or equal to 1, preferably between 1 and 2, for example the ratio is equal to 1.
• the aforementioned use is implemented by reactive distillation.
• Organopolysiloxane 02 n 100 viscosity 350 mPa.s
• Organopolysiloxane n 100 (waste oil used as a heating bath for several years) viscosity 350 mPa.s
• Organopolysiloxane 06 viscosity 450 mPa.s
• Organopolysiloxane 07 viscosity 100 mPa.s
• Organopolysiloxane 08 50% weight of 07 + 50% weight of 01 the viscosity of the mixture is 100 mPa.
• Organopolysiloxane 09 50% weight of 01 + 50% weight of silicone gum of formula
• the viscosity of the mixture is less than 60,000 mPa.s
• Organopolysiloxane 010 viscosity 250 mPa.s
• Organopolysiloxane 01 1 50% weight of 01 + 50% weight of PDMS with 5% Si-Ph pattern relative to the total number of patterns and a viscosity of 60,000 mPa.s
• Organopolysiloxane 012 50% by weight of 01 + 50% by weight mixture of 2 organopolysiloxanes of type 05 but with a number of different patterns, one having a viscosity of 10,000 mPa.s and the other a viscosity of 60,000 mPas.s and a crosslinking catalyst
• Organopolysiloxane 013 50% by weight of 01 + 50% by weight of a mixture of 2 organopolysiloxanes of type 05 but with a number of different patterns, one having a viscosity of 10,000 mPa.s and the other a viscosity of 60,000 mPas.s and approximately 5% by weight of a silicone oil comprising Si-H units
• Organopolysiloxane 014 01 + crosslinked silicone gel coming from the crosslinking between 012 and 013 free of fillers
• the organopolysiloxane, the alkaline salt and the multidentate complexing agent are introduced and are heated to a temperature T for 30 minutes to 1 hour. Then the reaction mixture is distilled under reduced pressure for 20-25 minutes.
• the D3/D4/D5/other ratio was determined between the integrated intensity of the signals (D3/D4/D5/others) in the 29Si-NMR spectrum, this ratio corresponds to a ratio by weight.
• Example 1 The protocol of Example 1 is implemented with KOSiMes (SA1) as the alkaline salt and an 18-6 crown ether (CM1). The reaction mixture is heated for 30 minutes before reactive distillation (temperature and pressure mentioned above).
• SA1 KOSiMes
• CM1 18-6 crown ether
• organopolysiloxane used is organopolysiloxane 01.
• Example 1 The protocol of Example 1 is implemented with KX as the alkaline salt and an 18-6 crown ether (CM1). The reaction mixture is heated for 1 h before reactive distillation at a temperature of 140°C and a pressure of 10 mbar for 20-25 min.
• CM1 18-6 crown ether
• Organopolysiloxane is 01.
• Example 1 The protocol of Example 1 is implemented with KOSiMes (SA1) as an alkaline salt and a multidentate complexing agent.
• SA1 KOSiMes
• the reaction mixture is heated for 1 h before reactive distillation at a temperature of 140°C and a pressure of 10 mbar for 20-25 min.
• Organopolysiloxane is 01.
• Example 1 The protocol of Example 1 is implemented with KOSiMes (SA1) as the alkaline salt and an 18-6 crown ether (CM1). The reaction mixture is heated for 1 hour before reactive distillation, at a temperature of 140°C and a pressure of 10 mbar for 20-25 min.
• SA1 KOSiMes
• CM1 18-6 crown ether
• Example 1 The protocol of Example 1 is implemented with different catalytic systems, at a temperature of 140°C.
• the reaction mixture is heated for 30 minutes before reactive distillation at a temperature of 140°C and a pressure of 10 mbar for 20-25 min.
• Organopolysiloxane is 01.
• Example 7 Example with an oil from chlorosilane hydrolysis reaction by-product
• Example 1 The protocol of Example 1 is implemented with different catalytic systems.
• the reaction mixture is heated to 150°C for 30 minutes before reactive distillation at a temperature of 150°C and a pressure of 5 mbar for 30 min.
• Organopolysiloxane is an oil derived from chlorosilane hydrolysis reaction byproducts comprising at least 95% of an organopolysiloxane comprising approximately 2% Si-H group, and other reaction products such as product residues. reaction, catalyst, etc.

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