Formation of organopolysiloxanes by depolymerization of silicone polymers

Abstract

The present invention generally relates to the reuse, reprocessing or recycling of silicone polymers. More precisely, the method of the present invention relates to the preparation of organopolysiloxanes OR by depolymerizing at least one silicone S in the presence of an acid catalyst and at least one chain blocker Bc having at least one siloxane functional group. These organopolysiloxanes OR can then be used in polymerization reactions or directly in various formulations.

Description

[Technical Field]

[0001] The present invention relates generally to the reuse, reprocessing, or recycling of silicone polymers. More specifically, the method of the present invention relates to the depolymerization of silicone polymers to obtain low molecular weight organopolysiloxanes OR that can be used in subsequent polymerization reactions or directly in various formulations. [Background technology]

[0002] A major societal and industrial challenge for the coming years is the ecological transition. From an economic point of view, therefore, the "linear" (take-make-use-dispose) economic model must eventually be replaced by a circular one.

[0003] Circular economy refers to an economic system based on a model that replaces the concept of "used" products with the reduction, alternative reuse, recycling and recovery of these materials in production / distribution and consumption procedures in order to achieve sustainable development for the benefit of present and future generations.

[0004] With the expansion of the silicone market and its applications, recycling used silicone products has become a major challenge in the silicone industry. Silicone recycling can reduce gas (CO, CO2) emissions associated with the silicone industry by 75% and silicone waste by 65%.

[0005] Additionally, cyclic silicones or organopolysiloxanes, such as octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5), are currently and will continue to be subject to use restrictions. These cyclic compounds not only pose environmental risks due to their non-biodegradability, but are also suspected endocrine disruptors and carcinogens.

[0006] Thus, in 2018, European regulations limited the content of D4 and D5 in rinse-off cosmetics to 0.1% by weight. These regulations will soon be extended to other cosmetic products and other areas of silicone use.

[0007] Therefore, there is a need to provide a process for providing silicone products that are free of cyclic silicones, or at least have a low content of cyclic silicones.

[0008] In the prior art, the depolymerization of organopolysiloxanes has been described by implementing a variety of processes.

[0009] Japanese Patent Application Laid-Open Publication No. 2002-348407, filed in 2002, discloses a method for chemically converting silicone products, such as silicone resins and silicone molds, into linear polysiloxanes. However, this method requires a large amount of acid catalyst (12%), and the resulting product is a mixture with cyclic compounds formed by a reverse cleavage reaction, commonly known as a backbiting reaction.

[0010] Recently, U.S. Patent Application Publication No. 20200377686 (2020) describes a process for recycling silicones (silicone oils, resins) through chemical conversion to obtain α,ω-diacetoxypolydimethylsiloxanes. However, this process requires the reaction medium to be heated and placed in an excess amount of acetic anhydride.

[0011] Additionally, α,ω-diacetoxypolydimethylsiloxanes can then be chemically modified to obtain polydimethylsiloxanes with hydroxy or acetoxy end groups that can be used in adhesive compositions or sealing products.

[0012] A similar process was described in US Patent Application No. 2022119617 in 2022. The resulting α,ω-diacetoxypolydimethylsiloxane is recycled to obtain α,ω-diisopropoxypolydimethylsiloxane or polydimethylsiloxane-polyoxyalkylene block polymers.

[0013] Therefore, there is interest in providing alternative processes for depolymerizing silicones to produce organopolysiloxanes that can be directly reused in subsequent formulations. In particular, there is interest in providing catalyst systems that enable this depolymerization to be carried out at lower temperatures, with reduced catalyst usage, making the process robust, selective, and flexible. There is also interest in ensuring control over the molecular weight of the resulting product. This potential opens up new possibilities for the use and application of such polymers. Summary of the Invention [Problem to be solved by the invention]

[0014] Therefore, one of the objectives of the present application is to provide a process for depolymerizing silicones that allows for control of the molecular weight of the final product while varying the chemistry of the end groups.

[0015] Another object of the present application is to provide a catalyst system for carrying out this process.

[0016] Another object of the present application is to provide a simple and non-toxic catalyst system suitable for industrialization of the process.

[0017] Another object of the present application is to provide a process that is satisfactory from an industrial point of view and in line with green chemistry.

[0018] Another objective of the present application is to obtain, at the end of this process, an organopolysiloxane OR having a low content of cyclic organopolysiloxanes.

[0019] Other objects of the present invention will become apparent from the following description. [Means for solving the problem]

[0020] Surprisingly, the Applicant has developed a catalyst system that meets these expectations. The present invention therefore relates to a process for the preparation of organopolysiloxanes OR by depolymerizing at least one silicone S in the presence of an acid catalyst selected from benzenesulfonic acid derivatives of formula (VIa), alone or in mixtures, and at least one chain blocker Bc having at least one siloxane functional group: [ka] R1 and R2 represent hydrogen atoms, and R3=C n H 2n+1 (5≦n≦20, preferably 10≦n≦20), Or, R1 and R3 represent a hydrogen atom, and R2=C n H 2n+1 (5≦n≦20, preferably 10≦n≦20), Or, R2 and R3 represent hydrogen atoms, and R1=C n H 2n+1 (5≦n≦20, preferably 10≦n≦20).

[0021] In this case, the acid catalyst and chain blocker Bc allow the end group chemistry to be varied during the depolymerization reaction while controlling the molecular weight of the final product. DETAILED DESCRIPTION OF THE INVENTION

[0022] Detailed description of the invention: Silicones, also known as organopolysiloxanes, are polymeric materials consisting of alternating silicon and oxygen atoms with various organic radicals bonded to the silicon.

[0023] In the present invention, silicone, silicone product, silicone polymer, or organopolysiloxane is understood to mean a polymer that comprises a siloxane (Si-O-Si) skeleton in which silicon and oxygen atoms are arranged alternately, and various organic groups bonded to the silicon atoms.These silicone polymers can be liquid or solid, depending on the molecular weight and the degree of crosslinking.

[0024] The silicones S of the present invention may be of any type, for example linear or branched organopolysiloxanes O, such as oils or gums, crosslinked organopolysiloxanes O, such as resins, gels or elastomers, or mixtures of such compounds.

[0025] The organopolysiloxane O is in particular an oil and preferably has a kinematic viscosity at 25°C of 10,000 to 600,000 mPa·s, preferably 30,000 to 600,000 mPa·s at 25°C.

[0026] All viscosities mentioned in this specification correspond to kinematic viscosity values ​​at 25° C., called “Newtons”, i.e. kinematic viscosities measured using a Brookfield viscometer in a manner known per se, at shear rate gradients sufficiently low that the measured viscosity is independent of the velocity gradient.

[0027] The term gum is typically used for organopolysiloxane compounds with a viscosity greater than 600,000 mPa.s and a molecular weight greater than 300,000 g / mol.

[0028] These organopolysiloxanes O may, for example, contain one or more of the following functional groups: -OH; -H; alkenyl, especially containing 2 to 6 carbon atoms, preferably vinyl; -O-Alk, where Alk represents an alkyl group containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl; -(O-Alk)x, where Alk represents an alkyl group containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl, and x represents an integer from 2 to 200; - a linear or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, substituted with at least one fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched.

[0029] Preferably, the functional group is selected from: -OH; -H; alkenyl, especially containing 2 to 6 carbon atoms, preferably vinyl; - a linear or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, substituted with at least one fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched.

[0030] Preferably, the organopolysiloxane O may contain one or more functional units, such as H, OH, alkenyl (preferably vinyl), aryl, or cyclic amine, as defined above. The organopolysiloxane O may be partially crosslinked. The organopolysiloxane O may in particular be a used organopolysiloxane that has been used, for example, as a heat transfer fluid and is recommended for recycling, thereby making it possible for the method of the present invention to produce an organopolysiloxane OR that can be directly used in industrial processes. When using used organopolysiloxane O, the organopolysiloxane may contain other components, such as additives, pigments, etc. The inventors have shown that it is possible to carry out the depolymerization reaction and the formation of organopolysiloxane OR under such conditions.

[0031] According to one embodiment of the present invention, the organopolysiloxane O comprises: at least 500, preferably at least 700, siloxy units of formula (I): R c SiO (4-c) / 2 (I) During the ceremony, R may be the same or different and represent: alkyl groups containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl; or an aryl group containing 6 to 10 carbon atoms, preferably phenyl; c=0, 1, 2, or 3; and optionally one or more units of formula (II): R 1 d R e SiO (4-d-e) / 2 (II) During the ceremony, R is as defined above; R 1 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), -(O-Alk) radicals, where Alk represents an alkyl radical containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably OCH3 or OC2H5, -(O-Alk)x radicals, where Alk represents an alkyl group containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl, and x represents an integer from 2 to 200; - a linear or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, substituted with at least one fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched; -hydrogen; d=1, 2 or 3, preferably d=1 or 2, more preferably d=1; e=0, 1 or 2; the sum of d+e=1, 2 or 3.

[0032] In the above formula, when multiple R groups are present, or when multiple R 1 It is understood that when groups are present they may be the same or different from one another.

[0033] Preferably, in the above formula, R 1 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), a linear or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, substituted with at least one fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched, or -hydrogen.

[0034] In the present invention: - "M" siloxy units have the formula YSiO 1 / 2 represents a siloxy unit. - "D" siloxy units have the formula YSiO 2 / 2 represents a siloxy unit. - "T" siloxy units have the formula YSiO 3 / 2 represents a siloxy unit. - "Q" siloxy units have the formula SiO 4 / 2 represents a siloxy unit. The symbol for Y is R or R 1 is. The organopolysiloxane O may optionally be linear or branched and may in particular comprise T and Q units.

[0035] According to a preferred embodiment, the organopolysiloxane O is selected from compounds of formula (III): R 1 a R (3-a) SiO-(SiR2O)n1 -(SiR 1 RO) m1 -SiR 1 a R (3-a) (III) During the ceremony: R may be the same or different and represent: an alkyl group containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl, or - aryl groups containing 6 to 10 carbon atoms, preferably phenyl; R 1 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), -(O-Alk) radicals, where Alk represents an alkyl radical containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably OCH3 or OC2H5, -(O-Alk)x radicals, where Alk represents an alkyl group containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl, and x represents an integer from 2 to 200; a linear or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, substituted with at least one fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched, or -hydrogen; a is an integer and represents 0, 1, 2, or 3, preferably 0, 1, or 2, and more preferably 0 or 1; -n1 represents an integer from 500 to 10,000, preferably from 1,000 to 5,000, more preferably from 500 to 5,000, and even more preferably from 600 to 2,000; -m1 represents an integer of 0 to 100, preferably 0 to 50, more preferably 0 to 30, and preferably m=0.

[0036] Particularly preferably, the organopolysiloxane O is a compound of formula (III), in which R 1 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), a linear or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, substituted with at least one fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched, or -hydrogen.

[0037] Particularly preferably, the organopolysiloxane O is a compound of formula (III), in which R 1 may be the same or different and represent: -CH3, vinyl, H, (C1-C5) alkyl-CF3 or OH.

[0038] Particularly preferably, the organopolysiloxane O is a compound of formula (III) in which R may be the same or different and represent CH3 or phenyl, preferably CH3; R 1 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), a linear or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, optionally substituted with at least one fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched, or -hydrogen.

[0039] Particularly preferably, the organopolysiloxane O is a compound of formula (III) in which R may be the same or different and represent CH3 or phenyl, preferably CH3; R 1 may be the same or different and represent CH3, vinyl, H, (C1-C5) alkyl-CF3 or OH.

[0040] The silicones S of the present invention may be crosslinked silicone materials, such as gels or elastomers. Crosslinked silicone materials are well known to those skilled in the art. These materials can be obtained, inter alia, by polycondensation, radical polymerization, or polyaddition under heat or UV irradiation. Silicone products are diverse. For example, they are used in food applications such as baking molds, medical applications, and in the pharmaceutical field, such as baby bottle nipples, catheters, implants, and medical tubing. In the industrial field, silicones are often used as sealing materials and membrane materials. In the automotive field, they are used as hose and cable coatings, insulating materials, and vibration damping materials.

[0041] Silicone elastomers are cross-linked silicone materials containing fillers such as silica, which give them excellent mechanical properties. By varying the silicone oil, fillers, additives, and cross-linking methods, silicone elastomers can have a wide range of properties and colors.

[0042] Silicone elastomers are divided into three main groups that are well known to those skilled in the art.

[0043] High-temperature vulcanization (HTV) or heat-cured rubber (HCR) elastomers are silicone elastomers obtained from very high-viscosity silicone compositions containing silicone gums and fillers. They are vulcanized at high temperatures (typically 140°C to 200°C). Crosslinking can be achieved by radical crosslinking, peroxide-catalyzed crosslinking, or by addition reactions catalyzed by platinum compounds.

[0044] Liquid silicone rubber (LSR) is a silicone elastomer derived from a composition containing viscous silicone oil and fillers. Crosslinking occurs via an addition reaction at temperatures similar to those of HTV, but typically occurs much faster than HTV.

[0045] The third group is silicones obtained by crosslinking silicone compositions at room temperature from silicone oils and fillers crosslinked by polycondensation or polyaddition reactions. These elastomers are known as room temperature vulcanizing (RTV) silicone elastomers. These compositions are available in one-component and two-component systems.

[0046] In the present process, silicone S also refers to silicone-based materials, for example materials containing at least 0.1% by weight of silicone relative to the total weight of the silicone-based material. Traditionally, these materials are found in silicone-coated textiles (airbags or synthetic leather) or silicone coatings (food paper).

[0047] The silicone-based material may contain up to 100% by weight of silicone, preferably up to 99.9% by weight of silicone, based on the total weight of the silicone-based material. These silicone-based materials may contain additives or fillers such as dyes, silica, calcium carbonate, calcium oxide, celite, quartz, titanium oxide, cerium hydroxide, magnesium oxide, mica, etc.

[0048] According to one embodiment, the silicone S comprises silica, calcium carbonate, quartz, titanium oxide, magnesium oxide, mica, and mixtures thereof.

[0049] In the present invention, the number of moles of (Si-O) refers to the number of moles of (Si-O) bonds in the silicone S. When the formula of the raw silicone S is unknown, particularly in the case of a compounded commercial product, it is possible to estimate the number of moles of (Si-O) bonds. Specifically, in the case of a compounded silicone elastomer, those skilled in the art know that the amount of filler is between 20% and 40% by weight. Therefore, if the amount of filler is estimated to be an average of 30% by weight, the silicone will be 70% by weight, and the number of moles of (Si-O) bonds can be calculated from the average molar mass of the repeating units.

[0050] In the context of this application, the term chain breaker Bc has at least one siloxane functional group.

[0051] In the method of the present invention, the chain breaker Bc is represented by formula (IV): [ka] During the ceremony: R 1 may be the same or different and represent: - linear or branched alkyl groups containing 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, optionally substituted with heteroatoms O, N, S or halides; - an alkenyl group containing 2 to 6 carbon atoms, - a cycloalkyl group containing 5 to 10 carbon atoms, optionally substituted with heteroatoms O, N, S or halides; -C6~C 18 an aryl group of the formula -hydroxy group, or -hydrogen, R 2 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), - a linear or branched alkyl group containing 1 to 12 carbon atoms, preferably 1 to 5 carbon atoms, optionally substituted with at least one heteroatom O, N, S, or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein the alkyl is linear or branched; or -hydrogen; q is an integer of 1 to 50, preferably 1 to 20, and more preferably 1 to 10.

[0052] In another embodiment, the chain breaker Bc is represented by formula (IV), wherein: R 1 may be the same or different and represent CH3 or phenyl, preferably CH3; R 2 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), - a linear or branched alkyl group containing 1 to 12 carbon atoms, preferably 1 to 5 carbon atoms, optionally substituted with at least one heteroatom O, N, S or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched, or -Optionally substituted C6 to C 18 an aryl group of the formula -hydrogen; q is an integer of 1 to 50, preferably 1 to 20, and more preferably 1 to 10.

[0053] Particularly preferably, the chain breaker Bc is of formula (IV), wherein: R 1 are identical and represent CH3, R 2 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), - linear or branched alkyl groups containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, -Optionally substituted C6 to C 18 an aryl group of the formula -hydrogen, q is an integer of 1 to 20, preferably 1 to 10, and more preferably 1 to 5.

[0054] Other siloxane functional blocking agents according to the present invention are described on page 264 of the book "Chemistry and Technology of Silicones," published by Academic Press in 1968.

[0055] The chain breaker Bc may be present in a solvent, which is particularly advantageous for solubilization in the reaction medium. Examples of the solvent include non-polar solvents, such as organic solvents based on alkanes or aromatic hydrocarbons. Preferably, the solvent is selected from the group consisting of n-hexane, n-heptane, n-decane, n-dodecane, isododecane, EXXSOL D60, xylene, toluene, and mixtures thereof.

[0056] The amount of chain breaker Bc used in the process of the present invention is at least 10 moles per mole of (Si—O) bond in the silicone S. -4 moles, preferably 10 -3 ~5×10 -1 moles, preferably 10 -3 ~10 -2 moles, more preferably 3 x 10 -3 ~6×10 -1 mole, for example, 5 × 10 for 1 mole of (Si-O) bond in silicone S -3 It is a mole.

[0057] These chain breakers allow the functionalization of the organopolysiloxanes OR during the depolymerization reaction, thus making it possible to obtain organopolysiloxanes OR having, for example, Si-vinyl or Si-H groups.

[0058] If desired, mixtures of different chain breakers can be used in the process according to the invention, thus making it possible to obtain organopolysiloxanes OR with different functional groups at the chain ends.

[0059] In another embodiment, the method of the present invention can be carried out without the use of chain breaker Bc.

[0060] The acid catalyst used as a catalyst in the process of the present invention is selected, alone or in mixture, from the group comprising Bronsted acids having a pKa of 2 or less, such as trifluoromethanesulfonic acid, benzenesulfonic acid and derivatives thereof.

[0061] Preferably, the acid catalyst is selected from benzenesulfonic acid and its derivatives of formula (Va), alone or in mixtures: [ka] R1 and R2 represent hydrogen atoms, and R3=C n H 2n+1 (1≦n≦20), Or, R1 and R3 represent a hydrogen atom, and R2=C n H 2n+1 (1≦n≦20), Or, R2 and R3 represent hydrogen atoms, and R1=C n H 2n+1 (1≦n≦20).

[0062] In one embodiment, the acid catalyst is selected from benzenesulfonic acid and its derivatives of formula (Vb), alone or in mixtures: [ka] Wherein R=H or C n H 2n+1 (1≦n≦20).

[0063] More preferably, the acid catalyst is selected from benzenesulfonic acid derivatives of formula (VIa), alone or in mixture: [ka] R1 and R2 represent hydrogen atoms, and R3=C n H 2n+1 (5≦n≦20, preferably 10≦n≦20), Or, R1 and R3 represent a hydrogen atom, and R2=C n H 2n+1 (5≦n≦20, preferably 10≦n≦20), Or, R2 and R3 represent hydrogen atoms, and R1=C n H 2n+1 (5≦n≦20, preferably 10≦n≦20).

[0064] In one embodiment, the acid catalyst is selected from benzenesulfonic acid derivatives of formula (VIb), either alone or in mixtures: [ka] In the formula, R=C n H 2n+1 (5≦n≦20, preferably 10≦n≦20).

[0065] It should be noted that the alkyl groups described in formulas (Va), (Vb), (VIa) and (VIb) may be primary, secondary or tertiary alkyl groups.

[0066] More preferably, the acid catalyst is HDBS, also known as 4-dodecylbenzenesulfonic acid (CAS 121-65-3).

[0067] Alternatively, the acid catalyst is selected from Bronsted acids with a pKa of -2 or less, such as perfluoroalkanoic acids, such as trifluoromethanesulfonic acid (triflic acid), pentafluoroethanesulfonic acid, heptafluoropropanesulfonic acid, or chlorinated derivatives, alone or in mixtures.

[0068] Depending on the nature of the acid catalyst, it may be dissolved in a solvent. Preferably, the solvent is a non-polar solvent. In particular, the solvent may be an alkane-based or aromatic hydrocarbon-based organic solvent. Preferably, the solvent is the same as the solvent selected during the depolymerization reaction. Therefore, the solvent may be an alkane-based or aromatic hydrocarbon-based organic solvent.

[0069] The amount of acid catalyst used in the method of the present invention is 0.001% by weight to 3% by weight, preferably 0.05% by weight to 1% by weight, more preferably 0.1% by weight to 1% by weight, for example 0.4% by weight, based on the weight of silicone S.

[0070] In one embodiment, the organopolysiloxane OR may have functional groups at the chain ends derived from chain blockers, such as vinyl functional groups, Si-H functional groups, or Si-aryl functional groups.

[0071] They may be the same or different depending on how the process is carried out.The organopolysiloxane OR defined above may optionally comprise T and Q units.

[0072] According to one embodiment of the present invention, the organopolysiloxane OR comprises: at least two siloxy units of formula (VII): [R 2 R 1 2Si(OSiR 1 2) q ]-O-SiR c O (3-c) / 2 (VII) During the ceremony R may be the same or different and represent: alkyl groups containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl; an aryl group containing 6 to 10 carbon atoms, preferably phenyl; c=1, 2 or 3; R 1may be the same or different and represent: - linear or branched alkyl groups containing 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, optionally substituted with heteroatoms O, N, S or halides; - an alkenyl group containing 2 to 6 carbon atoms, - a cycloalkyl group containing 5 to 10 carbon atoms, optionally substituted with heteroatoms O, N, S or halides; -C6~C 18 an aryl group of the formula -hydroxy group, or -hydrogen, R 2 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), - a linear or branched alkyl group containing 1 to 12 carbon atoms, preferably 1 to 5 carbon atoms, optionally substituted with at least one heteroatom O, N, S or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched; -Optionally substituted C5~C 10 cycloalkyl groups, -Optionally substituted C6 to C 18 an aryl group, or -hydrogen; q is an integer of 1 to 50, preferably 1 to 20, and more preferably 1 to 10. and one or more, preferably 10 to 1500 units, preferably 50 to 1000 units, more preferably 100 to 500 units, of units of formula (VIII): SiR 3 d R e O (4-d-e) / 2 (Formula VIII) During the ceremony: R may be the same or different and is as defined above; R 3 may be the same or different, and 1as defined in the group; d=0, 1, 2, preferably d=0 or 1; e=1, 2, or 3; d+e=1, 2, or 3.

[0073] Preferably, in the above formula, R 3 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl; -hydroxy group (OH); - a linear or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, substituted with at least one fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched; -hydrogen.

[0074] According to one embodiment of the present invention, the organopolysiloxane OR may be a compound of formula (IX): [ka] During the ceremony R may be the same or different and represent: alkyl groups containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl; an aryl group containing 6 to 10 carbon atoms, preferably phenyl; R 1 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), -(O-Alk) radicals, where Alk represents an alkyl radical containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably OCH3 or OC2H5, -(O-Alk)x radicals, where Alk represents an alkyl group containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl, and x represents an integer from 2 to 200, or -hydrogen; R 2 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), - a linear or branched alkyl group containing 1 to 12 carbon atoms, preferably 1 to 5 carbon atoms, optionally substituted with at least one heteroatom O, N, S or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched; -Optionally substituted C5~C 10 cycloalkyl groups, -Optionally substituted C6 to C 18 an aryl group, or -hydrogen; q is an integer of 1 to 50, preferably 1 to 20, and more preferably 1 to 10; n2 represents an integer of 10 to 1500, preferably 10 to 1000, more preferably 50 to 1000, and further preferably 100 to 500; m2 represents an integer of 0 to 100, preferably 0 to 50, more preferably 0 to 30, and preferably m=0.

[0075] According to a preferred embodiment of the present invention, the organopolysiloxane OR is a compound of formula (IX): During the ceremony, R may be the same or different and represent CH3 or phenyl, preferably CH3; R 1 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), a linear or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, substituted with at least one fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched, or -hydrogen; R 2 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), - a linear or branched alkyl group containing 1 to 12 carbon atoms, preferably 1 to 5 carbon atoms, optionally substituted with at least one heteroatom O, N, S or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched; -Optionally substituted C5~C 10 cycloalkyl groups, -Optionally substituted C6 to C 18 an aryl group, or -hydrogen; q is an integer of 1 to 50, preferably 1 to 20, and more preferably 1 to 10; n2 represents an integer of 10 to 1500, preferably 10 to 1000, more preferably 50 to 1000, and further preferably 100 to 500; m2 represents an integer of 0 to 100, preferably 0 to 50, more preferably 0 to 30, and preferably m=0.

[0076] According to a particularly preferred embodiment of the present invention, the organopolysiloxane OR of the present invention is a compound of formula (IX), in which: R may be the same or different and represent CH3 or phenyl, preferably CH3; R 1 may be the same or different and represent CH3, vinyl, H, (C1-C5) alkyl-CF3 or OH; R 2 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), - linear or branched alkyl groups containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, -Optionally substituted C6 to C 18 an aryl group, or -hydrogen; q is an integer of 1 to 20, preferably 1 to 10, and more preferably 1 to 5; n2 represents an integer of 10 to 1500, preferably 10 to 1000, more preferably 50 to 1000, and further preferably 100 to 500; m2 represents an integer of 0 to 100, preferably 0 to 50, more preferably 0 to 30, and preferably m=0.

[0077] In one embodiment, the organopolysiloxane OR of the present invention is a compound of formula (X), wherein: [ka] Formula (X) R may be the same or different and represent: alkyl groups containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl; an aryl group containing 6 to 10 carbon atoms, preferably phenyl; R 1 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), -(O-Alk) radicals, where Alk represents an alkyl radical containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably OCH3 or OC2H5, -(O-Alk)x radicals, where Alk represents an alkyl group containing 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably methyl, and x represents an integer from 2 to 200; - a linear or branched alkyl group containing 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, substituted with at least one fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched; hydrogen, or a --CH2CH2(R3SiO)n3 group, where R is as defined above and n3 represents an integer of 0 to 1000, preferably 0 to 500, and more preferably 0 to 200; R2 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group (OH), - a linear or branched alkyl group containing 1 to 12 carbon atoms, preferably 1 to 5 carbon atoms, optionally substituted with at least one heteroatom O, N, S or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, such as (C1-C5) alkyl-CF3, wherein alkyl is linear or branched; -Optionally substituted C5~C 10 cycloalkyl groups, -Optionally substituted C6 to C 18 an aryl group, or -hydrogen; q is an integer of 1 to 50, preferably 1 to 20, and more preferably 1 to 10; n2 represents an integer of 10 to 1500, preferably 10 to 1000, more preferably 50 to 1000, and further preferably 100 to 500; m2 represents an integer of 0 to 100, preferably 0 to 50, more preferably 0 to 30, and preferably m=0; n3 represents different or identical integers of 0 to 1000, preferably 0 to 500, and more preferably 0 to 200; a is equal to 0 or 1 and represents different or identical integers.

[0078] In the context of the present invention, degree of polymerization is understood to mean an integer representing the number of repeating siloxy units.

[0079] According to one embodiment of the process of the invention, the organopolysiloxane OR thus obtained has a degree of polymerization that is at least half that of the silicone S introduced, preferably at least one-third, and preferably at least one-fifth that of the silicone S introduced.

[0080] According to one embodiment of the process of the invention, the organopolysiloxane OR thus obtained has a degree of polymerization that is at least 10 times lower than that of the silicone S introduced.

[0081] In the sense of the present invention, the weight average molecular weight and number average molecular weight (M, respectively) of the various organopolysiloxanes OR w and M n (denoted by ) can be determined by size exclusion chromatography (SEC) in a solvent such as toluene at 40°C in the presence of polystyrene standards.

[0082] According to one embodiment of the method of the present invention, the organopolysiloxane OR thus obtained has a weight average molecular weight M of the silicone S introduced. w a weight average molecular weight M that is at least half, preferably at least one-third, and more preferably at least one-fifth, of w It has.

[0083] According to one embodiment of the method of the present invention, the weight average molecular weight M of the organopolysiloxane OR thus obtained is w is at least one-tenth of the weight average molecular weight of the introduced silicone S, or the weight average molecular weight M w It is possible that the number is at least 1 / 15 of that.

[0084] According to one embodiment of the method of the present invention, the organopolysiloxane OR of the present invention has a weight average molecular weight M w is 500 to 300,000 g / mol, preferably 1,000 to 150,000 g / mol, preferably 1,000 to 100,000 g / mol, and more preferably 5,000 to 40,000 g / mol.

[0085] According to one embodiment of the process of the invention, the organopolysiloxane OR thus obtained has a number average molecular weight M that is at least half that of the number average molecular weight of the silicone S introduced. n Preferably, the introduced silicone S has a number average molecular weight M n is at least one third, preferably at least one fifth, compared to

[0086] According to one embodiment of the method of the present invention, the organopolysiloxane OR thus obtained has a number average molecular weight M n is at least 1 / 10 times smaller than the number average molecular weight of the introduced silicone S, or the number average molecular weight M n It is possible that the figure is at least 15 times smaller than that of the previous figure.

[0087] According to one embodiment of the method of the present invention, the organopolysiloxane OR of the present invention is prepared by the method of the present invention, which has a number average molecular weight M n is 500 to 300,000 g / mol, preferably 1,000 to 150,000 g / mol, preferably 1,000 to 70,000 g / mol, and more preferably 2,500 to 30,000 g / mol.

[0088] According to one embodiment of the method of the present invention, the organopolysiloxane OR of the present invention is characterized in that its kinematic viscosity is 100 to 100,000 mPa s at 25°C, preferably 1,000 to 80,000 mPa s at 25°C, and more preferably 10,000 to 70,000 mPa s at 25°C.

[0089] In one embodiment, the organopolysiloxane OR of the present invention has a chain terminal (Si-O) bond content of 15% or less, preferably 10% or less, preferably 5% or less, and more preferably 1% or less, based on the total number of chain terminal silicon atoms of the organopolysiloxane OR of the present invention.

[0090] In the context of this application, the weight percentage of D4 in the product obtained according to the process of the present invention is quantitative. 29 The weight percentage of D4 in the product obtained according to the method of the present invention can be measured by Si NMR spectroscopy. Alternatively, the weight percentage of D4 in the product obtained according to the method of the present invention can be measured by a chromatogram from size exclusion chromatography (SEC) analysis.

[0091] In the present invention, cyclic organopolysiloxane refers to a compound of formula (XI): [ka] In the formula, n represents a natural number from 1 to 5.

[0092] Generally, within the meaning of the present invention, cyclic organopolysiloxanes consist of compounds of formula (XI) in which n is 2 or 3 or 4.

[0093] In other words, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), or mixtures thereof.

[0094] In one embodiment, the process according to the invention is characterized in that the content of cyclic organopolysiloxanes is less than 5%, preferably not more than 3%, preferably not more than 2%, and even more preferably not more than 1.5%, relative to the total weight of the organopolysiloxane OR of the invention.

[0095] In one embodiment, the process according to the invention is characterized in that the content of octamethylcyclotetrasiloxane (D4) is less than 5%, preferably not more than 3%, preferably not more than 2%, and even more preferably not more than 1.5%, relative to the total weight of the organopolysiloxane OR of the invention.

[0096] The process of the present invention is preferably carried out in a solvent, preferably a non-polar solvent, particularly an alkane or aromatic hydrocarbon organic solvent.

[0097] Preferably, the solvent is selected from n-hexane, n-heptane, n-decane, n-dodecane, isododecane, EXXSOL D60, xylene, toluene, and mixtures thereof.

[0098] In one embodiment, the method of the present invention is characterized in that the weight ratio of the weight of the silicone S to the weight of the solvent used is 0.01-15, preferably 0.1-5, and more preferably 0.1-2.

[0099] In one embodiment, the process of the present invention is characterized in that the depolymerization reaction is carried out without a solvent.

[0100] This embodiment is particularly advantageous because it allows for the elimination of the need for solvents and the subsequent disposal or recycling of solvents while still achieving satisfactory results in carrying out the process of the present invention.

[0101] Advantageously and preferably, the reaction is carried out at a temperature between 0°C and 100°C, preferably between 0°C and 50°C, more preferably between 10°C and 35°C, for example at room temperature.

[0102] According to the method of the present invention, the reaction time is 2 to 72 hours, preferably 5 to 24 hours, more preferably 8 to 24 hours, for example, 24 hours.

[0103] A person skilled in the art will know how to adapt these parameters depending on the nature of the reactor and the species used.

[0104] The method of the present invention may further include a step of neutralizing the acid catalyst, which can prevent side reactions from occurring and deactivate the acid catalyst.

[0105] Advantageously, this neutralization step is carried out by adding a base to the reaction medium or by thermal decomposition of the acid catalyst.

[0106] According to the process of the present invention, the base is selected from amines, alkali metal hydroxides, alkaline earth metal hydroxides, carbonates, bicarbonates, and mixtures thereof.

[0107] Preferably, the base is selected from the group of tertiary amines or bicarbonates.

[0108] Alternatively, the neutralization step is carried out by "pyrolysis."

[0109] The term "pyrolysis" is understood to mean heating at temperatures above 120°C for 10 minutes to 3 hours. A person skilled in the art knows how to adjust the operating conditions to optimize this pyrolysis step, which allows the catalyst to be decomposed and the depolymerization reaction to be stopped.

[0110] The process according to the invention may further comprise a filtration step for extracting the neutralized catalyst and / or excess base from the reaction medium. This step also makes it possible to extract the filler resulting from the silicones S depolymerized according to the process according to the invention. Those skilled in the art know how to adapt the filtration method depending on the size of the reactor and the species used in the process according to the invention.

[0111] According to a preferred embodiment of the present invention, the process of the present invention comprises the following three steps: 1) carrying out a process for preparing organopolysiloxane OR by depolymerizing at least one silicone S in the presence of at least one chain blocker Bc having at least one siloxane functional group and an acid catalyst; 2) neutralizing the acid catalyst mentioned in the previous step by adding a base to the reaction medium or by thermally decomposing the acid catalyst; and 3) Filtration of the reaction medium obtained at the end of step 2.

[0112] The present invention also relates to the use of organopolysiloxanes OR obtained by the process of the present invention as ingredients that can be used directly in a variety of silicone formulations used in the cosmetic, household, automotive, energy, and other fields.

[0113] The organopolysiloxanes OR derived from the silicones S detailed above in this application can be reused in various formulations to make new silicones S.

[0114] The present application therefore also relates to the use of organopolysiloxanes OR obtainable by the process according to the invention for the preparation of silicones S, for example for the preparation of silicone oils, resins, gums, gels or elastomers.

[0115] The present invention also relates to a method for producing silicones, in particular silicone oils, resins or gums, comprising the following steps: 1) carrying out the method for producing organopolysiloxane OR according to the present invention; 2) Producing silicones S, in particular oils, resins, gums or elastomers, from the organopolysiloxanes OR obtained in step 1).

[0116] In one embodiment, the method for preparing silicone S is characterized in that step 2 is carried out by a polyaddition or polycondensation reaction of a cationic or radical mechanism.

[0117] Step 2 consists in particular of producing a liquid silicone rubber (LSR), a high temperature vulcanizing (HTV) silicone elastomer, or a room temperature vulcanizing (RTV) silicone elastomer.

[0118] According to another embodiment, step 2 may consist in producing silicones S, which are used in particular in the cosmetics, health, household products, industrial technical formulations (seals, membranes, tubes), transport, such as motor or air transport, or energy sectors. [Example]

[0119] Silicones used in the examples: In the following: Me = methyl; Silicone S1: [ka] n=943;M n =70000g / mol Silicone S2: [ka] n=81(M n = 6000 g / mol), n = 943 (M n = 70000 g / mol), n = 1080 (M n = 80000 g / mol) Silicone S3: Silicone S3 is an RTV2 gel developed by ELKEM. This silicone is obtained by polyaddition reaction. Silicone S4: A commercially available silicone tube of unknown composition cut into small pieces. Silicone S5: [ka] Silicone S5 is a PDMS gum sold by ELKEM under the name BLUESIL™ FB silicone gum.

[0120] The acid catalyst is HDBS, also known as 4-dodecylbenzenesulfonic acid (CAS 121-65-3).

[0121] The solvent used in the examples is a non-polar solvent, preferably toluene or heptane.

[0122] Chain breakers used in the examples: Chain breaker Bc1: Divinyltetramethyldisiloxane (CAS 2627-95-4). Chain breaker Bc2: Hexamethyldisiloxane (CAS 107-46-0) Chain breaker Bc3: Tetramethyldisiloxane (CAS 3277-26-7) Chain breaker Bc4: [ka] In the formula n=13(M n = 977 g / mol).

[0123] Example 1: General protocol of the process: Silicone S, 120 ml of toluene, an acid catalyst, and a chain terminator Bc are added to a 250 ml round-bottom flask. The reaction medium is stirred at room temperature for 24 hours. A large excess of an inorganic base or an amine base is then added to the reaction medium, and a sample is taken. 1 H NMR and 29 Analyze by Si NMR.

[0124] In the examples below, the weight percent of D4 relative to the total weight of organopolysiloxane OR obtained by the process of the present invention is determined by size exclusion chromatography (SEC) in a solvent such as toluene at 40° C. in the presence of polystyrene standards.

[0125] Similarly, the number average molecular weight (M n ) is determined by the same method of size exclusion chromatography (SEC).

[0126] The value of QBc is given in various tables exemplified below, and represents the number of moles of Bc relative to the number of moles of (Si—O) bonds in the silicone S.

[0127] Example 2: Effect of the properties of the silicone S on the process of the present invention: The protocol of Example 1 is carried out using silicone S (30 g, approximately 404 mmol of (Si-O) bonds in silicone S for S1, S2, S3, and S5), HDBS (4400 ppm by weight, 0.132 g) as the acid catalyst, and Bc1 as the chain breaker Bc. The reaction medium is stirred for 24 hours at room temperature. Silicone S4 is cut from a commercially available silicone tube of unknown composition. For the remainder of this example, this tube is considered to consist of a significant amount of filler (30%) and a silicone amount of 70%.

[0128] Therefore, in this test, 30 g of silicone tubing is considered to contain 21 g of silicone S. 0.265 g of chain breaker Bc1 and 0.0925 g of HDBS were then introduced into the reaction medium.

[0129] The properties of the silicones S and the values ​​QBc are given in the table below.

[0130] [Table 1]

[0131] The results show that the process of the present invention is versatile and can be used with all types of silicones, including mixtures of silicones and silicones containing fillers.

[0132] Example 3: Influence of the nature of the chain breaker Bc on the process of the invention: The protocol of Example 1 is carried out using silicone S1 (30 g, 404 mmol of (Si-O) bonds in silicone S1), HDBS (4400 ppm by weight, 0.132 g) as acid catalyst, and chain blocker Bc. The reaction medium is left at room temperature for 24 hours.

[0133] The nature and value of the chain breaker QBc are shown in the table below.

[0134] [Table 2]

[0135] This test was repeated, replacing Silicone S1 with RTV2 silicone gel (Silicone S3) from ELKEM. Other operating conditions remained the same. Therefore, it was performed using Silicone S3 (30 g, 404 mmol of (Si-O) bonds in Silicone S3), HDBS (4400 ppm by weight, 0.132 g) as the acid catalyst, and chain breaker Bc, as shown in the table below:

[0136] [Table 3]

[0137] These tests demonstrate the versatility and robustness of the process according to the invention. In particular, the properties of the chain breaker Bc depend on the number average molecular weight (M n ) has a limited effect. This method can therefore be carried out with different silicones S and different chain breakers Bc. In the context of this example, the product obtained according to the method of the invention has a proportion of D4 of less than or equal to 2% by weight relative to the total weight of organopolysiloxane OR.

[0138] Example 4: Effect of the amount of chain breaker Bc in the process of the present invention: The protocol of Example 1 is carried out using silicone S1 (30 g, 404 mmol of (Si-O) bonds in silicone S1), HDBS (4400 ppm by weight, 0.132 g) as acid catalyst, and Bc1 as chain blocker. The reaction medium is left at room temperature for 24 hours.

[0139] The weights of Bc and the values ​​QBc are shown in the table below.

[0140] [Table 4]

[0141] In the context of each test in this example (Tests 1-8), the weight percentage of D4 is less than 2 wt. % relative to the total weight of product OR.

[0142] This test was repeated, replacing Silicone S1 with RTV2 silicone gel (Silicone S3) from ELKEM. The other operating conditions were the same as above. Therefore, Silicone S3 (30 g, 404 mmol of (Si-O) bonds in Silicone S3), HDBS (4400 ppm by weight, 0.132 g) as acid catalyst, and chain breaker Bc were used.

[0143] The weights of Bc and the values ​​QBc are shown in the table below.

[0144] [Table 5]

[0145] These two tests were carried out to determine the number average molecular weight (M n ) control is demonstrated. Varying the amount of chain breaker Bc material used affects the molecular weight of the OR. It can be seen that the product obtained according to the process of the present invention has a proportion of D4 of 1.3% by weight or less, based on the total weight of organopolysiloxane OR.

[0146] Example 5: Effect of the amount of acid in the process of the present invention: The protocol of Example 1 is carried out using silicone S1 (30 g, 404 mmol of (Si-O) bonds in silicone S1), HDBS (1100 ppm to 17600 ppm by weight) as the acid catalyst, and chain blocker Bc.

[0147] The QBc values ​​and molar amounts of HDBS are shown in the table below.

[0148] [Table 6]

[0149] It can be seen that, at a constant amount of chain blocker QBc, an increase in the amount of acid catalyst results in an increase in the proportion of D4.

[0150] Therefore, the amount of acid catalyst involved in the reaction simultaneously affects the reaction rate, the resulting average molecular weight, and the amount of undesired by-products such as D4.

[0151] Armed with the information disclosed in this invention, one skilled in the art can easily use the method of the present invention to obtain a desired number average molecular weight M while controlling the cyclic content. n The question then becomes how to adapt these parameters to obtain a polyorganosiloxane OR having the following properties:

[0152] Example 6: Comparison with the protocol in Japanese Patent Application JP 2002-348407 A: A 250 ml round-bottom flask equipped with a magnetic stirrer was charged with 20 g of PDMS S4, 47 g of toluene, and 2.4 g of HDBS solution. After stirring at room temperature for 1 hour, the silicone tubing was completely decomposed and dissolved. Next, a solution of 0.54 g of calcium hydroxide dissolved in 15 g of isopropanol was added to neutralize the mixture, and 50 g of water was added. The resulting mixture was stirred for 10 minutes. After standing for 30 minutes, a sample of the resulting organic phase was withdrawn, diluted to an appropriate concentration, filtered, and analyzed by size exclusion chromatography. The number-average molecular weight (M) of the resulting organopolysiloxane was 11,000 g / mol, with the amount of undesired by-products, such as octamethyltetrasiloxane (D4), equal to 15 wt.% relative to the total weight of the resulting organopolysiloxane. n ) is obtained.

[0153] Example 7: Influence of the nature of the acid catalyst: The protocol of Example 1 is carried out using silicone S1 (30 g, 404 mmol of (Si-O) bonds in silicone S1), acid catalyst (4400 ppm by weight), and chain blocker Bc. The nature of the acid catalyst used and the weight of the catalyst are shown in the table below.

[0154] [Table 7]

[0155] It is noted that tests 2 and 3 showed satisfactory results within the meaning of the present invention. However, it should be noted that trifluoromethanesulfonic acid provides 3% by weight of D4 relative to the total weight of organopolysiloxane OR.

[0156] In contrast, 4-dodecylbenzenesulfonic acid (CAS 121-65-3) demonstrates satisfactory performance of the process of the present invention, as already shown in the previous examples.

[0157] Example 8: Effect of reaction time on the process of the present invention: The protocol of Example 1 is carried out using silicone S1 (30 g, 404 mmol of (Si—O) bonds in silicone S1), HDBS (4400 ppm by weight, 0.132 g) as the acid catalyst, and chain blocker Bc.

[0158] The QBc values ​​and reaction times are shown in the table below.

[0159] [Table 8]

[0160] These tests also show that the number average molecular weight M of the polyorganosiloxane OR obtained according to the method of the present invention varies depending on the reaction time. n It has been demonstrated that it is possible to control

[0161] Example 9: Effect of temperature on the process of the present invention: The protocol of Example 1 is carried out using silicone S1 (30 g, 404 mmol of (Si—O) bonds in silicone S1), HDBS (4400 ppm by weight, 0.132 g) as the acid catalyst, and chain blocker Bc.

[0162] The following table shows the temperature, degree of polymerization of the product OR, and weight percent of D4:

[0163] [Table 9]

[0164] Depending on the temperature during the process of the present invention, the number average molecular weight M of the polyorganosiloxane OR obtained according to the process of the present invention can be n It becomes possible to control

[0165] Example 10: Effect of solvent content on the process of the present invention: The protocol of Example 1 is carried out using silicone S1 (30 g, 404 mmol of (Si—O) bonds in silicone S1), HDBS (4400 ppm by weight, 0.132 g) as the acid catalyst, chain blocker Bc, and toluene as the solvent.

[0166] In this example, five tests were performed using different amounts of solvent.

[0167] This example aims to explore the possible influence on the amount of solvent introduced into the process of the present invention.

[0168] The table below shows the amount of solvent introduced in the various tests:

[0169] [Table 10]

[0170] The amount of solvent introduced during the process of the present invention is determined by the number average molecular weight M of the polyorganosiloxane OR obtained according to the process of the present invention. n Furthermore, in the same example, the weight percentage of D4 relative to the total weight of product OR is 2% or less in each test.

[0171] Example 11: Reuse of silicone S2 depolymerized to organopolysiloxane OR into a new RTV2 formulation: In this example, we tested the ability to prepare an RTV2 gel using a functional organopolysiloxane OR (obtained under the conditions of Test 1 in Example 2). Therefore, recycled OR from Test 1 in Example 2, containing vinyl functional groups, was used in combination with a poly(methylhydrosiloxane)-co-poly(dimethylsiloxane)-type crosslinker with a [Si-H] / [Si-vinyl] ratio of 2.25. To obtain this RTV2 gel, a hydrosilation reaction was carried out in the presence of a Karstedt catalyst (275 ppm of a 2% Pt solution) and 1-ethynylcyclohexanol ([1-ethynylcyclohexanol] / [Pt] = 14.6 ppm) used as a modifier. The reaction mixture was then mixed, degassed, and crosslinked at 70 °C for 4 hours.

[0172] Attached Figure 1 shows a photograph of the RTV2 gel obtained under the conditions of this example. This RTV2 formulation was prepared twice under the same conditions, and each test showed similar physical properties. Specifically, the RTV2 gel obtained in the first test had a swelling degree of 280% and an extractables percentage of 10%, while the RTV2 gel obtained in the second test had a swelling degree of 285% and an extractables percentage of 10%.

[0173] This example therefore demonstrates that organopolysiloxane OR obtained according to the method of the present invention can be used in formulations to obtain silicone gels of the RTV2 type. Taking into account the information disclosed in the present invention, and in particular in this example, a person skilled in the art will know how to adapt the operating conditions for using organopolysiloxanes obtained according to the method of the present invention in other silicone formulations (HTV, RTV1, LSR).

Claims

1. A method for producing organopolysiloxane OR by depolymerizing at least one silicone S in the presence of: an acid catalyst chosen from benzenesulfonic acid derivatives of formula (VIa), alone or in mixture: 【Chemical 1】 R 1 and R 2 represents a hydrogen atom, R 3 =C n H 2n+1 (5≦n≦20, preferably 10≦n≦20), Or, R 1 and R 3 represents a hydrogen atom, R 2 =C n H 2n+1 (5≦n≦20, preferably 10≦n≦20), Or, R 2 and R 3 represents a hydrogen atom, R 1 =C n H 2n+1 (5≦n≦20, preferably 10≦n≦20), and at least one chain breaker Bc having at least one siloxane functional group.

2. 2. The method according to claim 1, wherein the acid catalyst is selected from benzenesulfonic acid derivatives of formula (VIb), alone or in mixture: 【Chemistry 2】 In the formula, R=C n H 2n+1 (5≦n≦20, preferably 10≦n≦20).

3. The chain breaker Bc is selected from compounds of formula (IV) 【Chemistry 3】 During the ceremony: R 1 may be the same or different and represent: - linear or branched alkyl groups containing 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms, optionally substituted with heteroatoms O, N, S or halides; - an alkenyl group containing 2 to 6 carbon atoms, - a cycloalkyl group containing 5 to 10 carbon atoms, optionally substituted with heteroatoms O, N, S or halides; -C 6 ~C 18 an aryl group of the formula -hydroxy group, or -hydrogen, R 2 may be the same or different and represent: alkenyl groups containing 2 to 6 carbon atoms, preferably vinyl, -hydroxy group, a linear or branched alkyl group containing 1 to 12 carbon atoms, preferably 1 to 5 carbon atoms, optionally substituted with at least one heteroatom O, N, S or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, or -hydrogen; q is an integer of 1 to 50, preferably 1 to 20, and more preferably 1 to 10.

4. The amount of the chain breaker Bc used in the process of the present invention is at least 10 moles per mole of (Si—O) bond in the silicone S. -4 moles, preferably 10 -3 ~5 x 10 -1 moles, preferably 10 -3 ~10 -2 mole, more preferably 3×10 per mole of (Si—O) bond in silicone S -3 ~6 x 10 -1 The method according to claims 1 to 3, wherein the amount is moles.

5. 5. The method according to any one of claims 1 to 4, wherein the amount of the acid catalyst is from 0.001% to 1% by weight, preferably from 0.05% to 1% by weight, and more preferably from 0.1% to 1% by weight, relative to the weight of the silicone S.

6. The organopolysiloxane OR has a number average molecular weight (M n 6. The method according to claim 1, wherein the molecular weight of the polymer (denoted as α, β, β) is 500 to 300000 g / mol, preferably 1000 to 150000 g / mol, more preferably 1000 to 70000 g / mol, and even more preferably 2500 to 30000 g / mol.

7. 7. The method according to claim 1, wherein the content of cyclic organopolysiloxane is less than 5% by weight, preferably not more than 3% by weight, preferably not more than 2% by weight, and more preferably not more than 1.5% by weight, based on the total weight of the organopolysiloxane OR.

8. The process according to any one of claims 1 to 7, wherein the reaction is carried out at a temperature of from 0°C to 100°C, preferably from 0°C to 50°C, more preferably from 10°C to 35°C.

9. The method of any one of claims 1 to 8, wherein the reaction is carried out in the presence of a non-polar solvent.

10. 10. The method according to any one of claims 1 to 9, characterized in that the weight ratio between the weight of silicone S and the weight of solvent used is between 0.01 and 15, preferably between 0.1 and 5, and even more preferably between 0.1 and 2.

11. 11. The method according to any one of claims 1 to 10, further comprising a step of neutralizing the acid catalyst, carried out by adding a base to the reaction medium or by thermally decomposing the acid catalyst.

12. Further, the following steps: 1) carrying out the process for preparing organopolysiloxane OR by depolymerizing at least one silicone S in the presence of at least one chain blocker Bc having at least one siloxane functional group and an acid catalyst; 2) neutralizing the acid catalyst described in the previous step by adding a base to the reaction medium or by thermally decomposing the acid catalyst; and 3) filtering the reaction medium obtained at the end of step 2 The method according to any one of claims 1 to 11, characterized in that it comprises:

13. 13. Use of organopolysiloxanes OR obtained by the process according to any one of claims 1 to 12 as components of silicone formulations for cosmetics, health, household products, industrial technical formulations, the transport sector, such as automotive and air transport, or the energy sector.

14. A process for making silicones S, in particular silicone oils, resins, gums or elastomers, comprising the following steps: 1) carrying out the method for producing organopolysiloxane OR according to any one of claims 1 to 12; 2) Producing silicone S from organopolysiloxane OR obtained in step 1).

15. 15. A process for making silicones S according to claim 14, characterized in that step 2 is carried out by a polyaddition or polycondensation reaction by a cationic or radical mechanism.

16. 16. Use of silicones S obtained by the process according to claim 14 or 15 in cosmetics, health, household products, industrial technical formulations, in the transport sector, such as motor transport or air transport, or in the energy sector.

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