Ring opening polymerization method

Abstract

The invention relates to a method for producing linear organopolysiloxanes OL by means of a ring-opening polymerization reaction from cyclic organopolysiloxanes OC by means of a basic catalyst B. More specifically, the method of the present invention makes it possible to obtain a controlled molar mass linear organopolysiloxane OL with a very low cyclic substance ratio. The invention also relates to a composition S1 used within the scope of the method according to the invention.

Description

TECHNICAL FIELD

[0001] The present invention relates to a process for the preparation of linear organopolysiloxanes OL by performing a ring-opening polymerization reaction in the presence of a cyclic organopolysiloxane OC, a basic catalyst B and a chain end-capper C. More precisely, the process of the invention makes it possible to obtain linear organopolysiloxanes OL of controlled molar mass with a very low residual rate of cyclic organopolysiloxane. BACKGROUND

[0002] One of the main challenges for the silicone industry in the coming years is the industrial synthesis of organopolysiloxanes with a very low or even zero residual rate of cyclic compounds.

[0003] To date, the industrial synthesis of organopolysiloxanes by polycondensation or by ring-opening polymerization leads to the formation of cyclic organopolysiloxanes such as octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) or other undesirable cyclic organopolysiloxanes. In conventional industrial processes, this undesirable product content can be as high as 10-15% relative to the total mass of linear organopolysiloxane obtained during synthesis, which corresponds to the thermodynamic equilibrium. Generally, this high cyclic product content requires the implementation of energy-intensive process steps (for example devolatilization steps at high temperature and / or under reduced pressure) to separate these by-products from the resulting linear organopolysiloxane. Omitting these steps makes it possible to increase production efficiency while reducing carbon dioxide emissions and thus obtaining a more environmentally friendly silicone product.

[0004] Thus, for economic and energy benefits, there is a need to develop new solutions to avoid or at least limit these lengthy and costly separation steps.

[0005] In addition, cyclic silicones or organopolysiloxanes such as octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) are currently and will be in the future subject to usage restrictions. In addition to the environmental risks posed by these cyclic compounds due to their non-biodegradability, they are suspected of being endocrine disruptors and of having potential carcinogenicity.

[0006] In this sense, in 2018, European regulations will limit the content of D4 and D5 to a content of 0.1% by mass in cosmetics to be flushed. Soon, this regulation will apply to other cosmetics, as well as other fields of application of silicones. For example in the electronics field, various restriction provisions tend to limit the content of cyclic organopolysiloxanes to values of less than 100 ppm.

[0007] There is therefore a need to develop a process that makes it possible to provide silicone products that do not contain cyclic silicones or at least have a low content of cyclic silicones. It would be particularly beneficial to provide a composition S that can be polymerized by ring-opening, which allows such a process to be implemented. It would also be beneficial to be able to reliably control the molar mass of the product formed. This possibility makes it possible to increase the use and application prospects of the polymers of this type obtained.

[0008] In the prior art, patent application US2012142956A1 teaches a process for preparing linear organopolysiloxanes OL in the presence of a quaternary ammonium such as tetramethylammonium hydroxide or choline. On the one hand, the examples of patent application US2012142956 disclose that no satisfactory yield of linear organopolysiloxanes OL was obtained in the presence of choline and its derivatives. On the other hand, with regard to the tests using tetramethylammonium hydroxide, there is a need to find a substitute for this catalyst and its derivatives, which are toxic to the human body and to the environment.

[0009] More recently, patent application WO2018051792 discloses a process for preparing linear organopolysiloxanes OL in the presence of a guanidine derivative as a basic catalyst. However, unlike the catalyst of the present invention, most guanidine derivatives need to be synthesized, unlike choline, which is commercially available. In addition, the process disclosed in patent application WO2018051792 requires the presence of chlorosilanes, which are known to be highly toxic compounds. SUMMARY

[0010] The development of this alternative technology makes it possible to manufacture silicones that are more environmentally friendly.

[0011] In addition, the present invention makes it possible to achieve the multiple objectives listed below, as well as those that will emerge by reading the description of the invention below.

[0012] SUMMARY OF THE INVENTION : One objective of the present application is thus to propose a process for preparing linear organopolysiloxanes OL by ring-opening polymerization of cyclic organopolysiloxanes OC, which makes it possible to control the molar mass of the final product, with a yield of linear organopolysiloxanes greater than 95%, preferably greater than 98%.

[0013] Another objective of the present application is to be able to control the nature of the chemical functional groups of the linear organopolysiloxanes OL obtained.

[0014] Another objective of the present application is to provide a composition S that can be polymerized by ring-opening, which makes it possible to implement this process.

[0015] Another objective of the present application is to propose a composition S that can be polymerized by ring-opening, which is low in toxicity and compatible with the industrialization of the process.

[0016] Another object of the present application is to propose a process which is satisfactory from an industrial point of view and which belongs to the so-called environmentally friendly chemistry.

[0017] Other objects will become apparent on reading the description of the application which follows.

[0018] Surprisingly, the Applicant has developed a composition S which can be polymerized by ring-opening which meets these expectations. Thus, the present application relates to a process for the preparation of linear organopolysiloxanes OL by ring-opening polymerization, said process comprising the following steps: a) use of a composition S which can be polymerized by ring-opening, comprising: i) at least one cyclic organopolysiloxane OC having three siloxane units, ii) at least one basic catalyst B of formula (I): Formula I in which: - R1, which are identical or different, represent an alkyl chain having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, - R2represents a hydrogen atom or a group -C(=0)-R3in which R3represents an alkyl group having from 1 to 12 carbon atoms; - X represents an anion chosen from the group comprising carboxylates and derivatives thereof, carbonates and derivatives thereof, hydroxyl groups, siloxanolates, silanolates, - n is a natural integer between 1 and 6, and iii) at least one chain-stopper C, b) optionally, subsequent addition to the composition S which can be polymerized by ring-opening mentioned in the preceding step of a chain-stopper C which is identical or different from the chain-stopper of step a) or of an acid A, c) obtaining of linear organopolysiloxanes OL.

[0019] In this case, the basic catalyst B and the chain-stopper C allow the molar mass of the final product to be controlled during the process of the application, while allowing the nature of the terminal chemical functions to be varied.

[0020] DETAILED DESCRIPTION OF THE INVENTION : Silicones, also known as organopolysiloxanes, are polymeric materials comprising alternating silicon and oxygen atoms and having various organo groups bonded to silicon.

[0021] Within the scope of the present invention, the term "silicone" or "silicone product" or "silicone polymer" or "organopolysiloxane" is understood to mean a polymer comprising a siloxane backbone (Si-O-Si) having alternating silicon and oxygen atoms, with various organyl groups bonded to the silicon. These silicone polymers can be liquid or solid, depending on the molar mass and the degree of polymerization.

[0022] Within the meaning of the present invention, the term "reaction mixture" is understood to mean all the reactive chemical species present in the composition S which can be polymerized by ring-opening, as mentioned above. One can mention for example the catalyst(s) B, the cyclic organopolysiloxane(s) OC, the chain end-stopper(s) C.

[0023] All the viscosities mentioned in the present disclosure correspond to the so-called "Newtonian" dynamic viscosity values at 25°C, i.e. the dynamic viscosity measured in a manner known per se using a Brookfield viscometer at a sufficiently low shear rate such that the measured viscosity is independent of the velocity gradient.

[0024] Within the scope of the present invention, the cyclic organopolysiloxane OC is represented by the following formula (II): Formula II wherein R, which is identical or different, is a radical representing an alkyl group having from 1 to 6 carbon atoms, an alkenyl group having from 2 to 6 carbon atoms or an aryl group having from 6 to 18 carbon atoms; and n represents a natural integer from 1 to 2.

[0025] Preferably, the cyclic organopolysiloxane OC is represented by the following formula (III): Formula III wherein R, which is identical or different, is a radical representing an alkyl group having from 1 to 6 carbon atoms, an alkenyl group having from 2 to 6 carbon atoms or an aryl group having from 6 to 18 carbon atoms.

[0026] Particularly, mention can be made of the commercially available cyclic organopolysiloxanes OC such as hexamethylcyclotrisiloxane (CAS 541-05-9), 2-vinyl-2',4,4',6,6'- pentamethylcyclotrisiloxane (CAS 18395-32-9), 2,4,6-trivinyl-2,4,6- trimethylcyclotrisiloxane (CAS 3901-77-7), hexaphenylcyclotrisiloxane (CAS 512-63-0), 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane (CAS 2374-14-3), 2,2,4-trimethyl-4,6,6-triphenyl-1,3,5,2,4,6- trioxatrisilinane (CAS 546-45-2), 1,3,5-trimethyl-1,3,5-triphenylcyclotrisiloxane (CAS 546-45-2), 2,4,6-trimethylcyclotrisiloxane (CAS 13269-39-1 ), 3,5- trivinyl-1,3,5-trimethylcyclotrisiloxane (CAS 3901-77-7), 2-vinyl-2,4,4,6,6- pentamethylcyclotrisiloxane (CAS 18395-32-9), 2,4,6,8-tetramethylcyclotetrasiloxane (CAS 2370-88-9), 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (CAS 2554-06-5), 2,4,6,8-tetramethyl-2,4,6,8-tetraphenylcyclotetrasiloxane (CAS 77-63-4), octaphenylcyclotetrasiloxane (CAS 546-56-5).

[0027] Advantageously, the cyclic organopolysiloxane OC is hexamethylcyclotrisiloxane (CAS 541-05-9).

[0028] According to one embodiment of the application, the process of the application uses at least two cyclic organopolysiloxanes OC having 3 siloxane units, for example a combination of hexamethylcyclotrisiloxane (CAS 541-05-9) and 2,4,6-trivinyl-2,4,6- trimethylcyclotrisiloxane (CAS 3901-77-7).

[0029] The introduction of these reagents into the reaction mixture is carried out simultaneously or sequentially. For example, it is possible to add first hexamethylcyclotrisiloxane and then 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane, or vice versa. This operating procedure is applicable to the various cyclic organopolysiloxanes OC having 3 siloxane units.

[0030] Within the scope of the present application, the basic catalyst B is represented by formula (IV): Formula IV wherein: R1, which are identical or different, represent an alkyl chain having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, R2represents a hydrogen atom or a group -C(=0)-R3, in which R3represents an alkyl group having from 1 to 12 carbon atoms; X represents an anion chosen from the group comprising carboxylates and their derivatives, carbonates and their derivatives, hydroxyls, siloxanols, silanols, and n is a natural integer between 1 and 6.

[0031] As examples of carboxylate anions, mention can be made in particular of salicylate, oxalate, malonate, gluconate, maleate or citrate.

[0032] As regards carbonate anions, mention can be made of bicarbonate and carbonate.

[0033] In the meaning of the application, the term "siloxanol" refers to an anionic compound of siloxanol of formula (V) below: Formula V wherein, R 1 which are identical or different, represent: - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, - an alkenyl group comprising from 2 to 6 carbon atoms, - a C6-C 18 aryl group, - a hydroxyl group, or R 2 which are identical or different, represent: - an alkenyl group comprising from 2 to 6 carbon atoms, preferably a vinyl group, - a hydroxyl group (OH), - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 5 carbon atoms, q is an integer from 1 to 20, preferably from 1 to 10, more preferentially from 1 to 5, and with the proviso that at least one group R 2 is a hydroxyl group (OH).

[0034] Preferentially, the term "siloxanol" refers to an anionic compound of formula (V) in which: R 1 which are identical or different, represent: - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, - an alkenyl group comprising from 2 to 6 carbon atoms, - A cycloalkyl group having 5-10 carbon atoms, optionally substituted with heteroatoms O, N, S or halides. - C6-C 18 Aryl, - Hydroxyl group, or R 2 If they are the same or different, it means: - Hydroxyl group (OH), q is an integer from 1 to 20, preferably from 1 to 10, and more preferably from 1 to 5.

[0035] Within the scope of this invention, the term "silanol" refers to anion associated with trimethylsilanol (CAS 1066-40-6) or triethylsilanol (CAS 597-52-4).

[0036] The anions associated with silanols represented by formula (VI) may also be specifically mentioned: Style VI in: R is the same or different, indicating: - Alkyl groups having 1-12 carbon atoms, - Cycloalkyl groups having 5-8 carbon atoms - Alkenyl groups having 2-12 carbon atoms, - Benzyl or phenyl, The group R is optionally substituted with an alkenyl, alkyl chain, cycloalkyl, aryl or heteroatom such as oxygen, sulfur or nitrogen, consisting of 2-6 carbon atoms.

[0037] Preferably, those skilled in the art can use compounds of trimethylsilanol (CAS 1066-40-6) or triethylsilanol (CAS 597-52-4).

[0038] Preferably, the alkaline catalyst B is represented by formula (VII): Equation VII in: R1 can be the same or different, representing an alkyl chain having 1-6 carbon atoms, preferably 1-3 carbon atoms; X represents an anion selected from the group consisting of: carboxylate and its derivatives, carbonate and its derivatives, hydroxyl group, siloxane group, and silanol group. And n is a natural integer from 1 to 6.

[0039] Preferably, the alkaline catalyst B is represented by the above formula (VII). in: R1 represents an alkyl chain having 1-6 carbon atoms, preferably 1-3 carbon atoms; X represents an anion selected from the group comprising hydroxyl or silanolate, and n is a natural integer from 1 to 6.

[0040] According to a particular embodiment of the application, the basic catalyst B is represented by the above formula (VII) in which: R1represents an alkyl chain having 1 or 2 carbon atoms; X represents a trimethylsilanolate or triethylsilanolate anion, and n is equal to 1.

[0041] Particularly, the basic catalyst B can be mentioned selected from choline hydroxide (CAS 123-41-1), silanolate choline, choline lactate (CAS 99150-55-7), triethylcholine hydroxide (CAS 3651-90-9), (2-hydroxyethyl)tripropylammonium hydroxide (CAS 96311-53-4), (2-hydroxyethyl)tributylammonium hydroxide, silanolate triethylcholine, choline bicarbonate (CAS 78-73-9) or choline salicylate (CAS 2016-36-6).

[0042] The molar amount of the basic catalyst B used in the process of the application is comprised between 150 ppm and 4000 ppm relative to the molar amount of the reaction mixture, preferably between 250 and 2500 ppm, more preferably between 250 ppm and 1500 ppm relative to the molar amount of the reaction mixture.

[0043] According to an embodiment of the application, the catalyst B is dissolved in a solvent selected from an alcohol or water.

[0044] According to an embodiment of the application, the alcohol is selected from: methanol (CAS 67-56-1), ethanol (CAS 64-17-5), propanol (CAS 71-23-8), isopropanol (CAS 67-63-0), butanol (CAS 71-36-3), allyl alcohol (CAS 107-18-6), benzyl alcohol (CAS 100-51-6), 3-buten-1-ol (CAS 627-27-0), an alcohol with long alkyl chains such as undecanol (CAS 112-42-5) or dodecanol (CAS 27342-88-7).

[0045] Preferably, the catalyst B is dissolved in methanol or water.

[0046] In the meaning of the present patent, the chain capping agent C is selected from H2O, an alcohol and derivatives thereof, or a silanol and derivatives thereof.

[0047] In the scope of the present patent, the chain capping agent C is selected from H2O or a compound of formula (VIII): Formula VIII wherein: Y represents a carbon atom or a silicon atom; R are identical or different and represent: - an alkyl group having 1 to 12 carbon atoms, - a cycloalkyl group having 5 to 8 carbon atoms, - an alkenyl group having 2 to 12 carbon atoms comprising 1 to 6 unsaturated carbon-carbon bonds, - an aryl group having 6 to 18 carbon atoms, preferably phenyl, - a benzyl group, - a group having at least 5, preferably at least 10, formulae R 1 c SiO (4-c) / 2 a siloxy group of the unit wherein R 1 are identical or different and represent an alkyl group comprising 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 comprising 6 to 10 carbon atoms, preferably phenyl; and c = 0, 1 or 2; and said group R can be unsubstituted or substituted by an alkyl chain having 1 to 12 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an aryl group having 6 to 18 carbon atoms or a heteroatom such as oxygen, sulphur or nitrogen.

[0048] Within the scope of the present application, the chain capping agent C is selected from H2O or a compound of formula (VIII): Y represents a carbon atom or a silicon atom; R are identical or different and represent: - an alkyl group having 1 to 12 carbon atoms, - a cycloalkyl group having 5 to 8 carbon atoms, - an alkenyl group having 2 to 12 carbon atoms, - an aryl group having 6 to 18 carbon atoms, preferably phenyl, - a benzyl group, - a group having at least 5, preferably at least 10, formulae R 1 c SiO (4-c) / 2 a siloxy group of the unit wherein R 1are identical or different and represent an alkyl group comprising 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 comprising 6 to 10 carbon atoms, preferably phenyl; and c = 0, 1 or 2.

[0049] In one embodiment of the application, the chain capping agent C is an alcohol or a silanol having a pKa of 10 to 16, preferably a pKa of 12 to 16, preferably a pKa of 14 to 16.

[0050] According to one embodiment of the application, the chain capping agent C is H2O.

[0051] According to one embodiment of the application, the chain capping agent C is a compound of formula (IX): Formula IX wherein: Y represents a carbon atom, R is identical or different and represents: - an alkyl group having 1 to 12 carbon atoms, - a cycloalkyl group having 5 to 8 carbon atoms, - an alkenyl group having 2 to 12 carbon atoms, - a benzyl group or a phenyl group, said group R can be unsubstituted or substituted with an alkyl chain having 1 to 12 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an aryl group having 6 to 18 carbon atoms or a heteroatom such as oxygen, sulfur or nitrogen.

[0052] According to one embodiment, the chain capping agent C is an alcohol selected from a primary alcohol or a secondary alcohol. Preferably, the chain capping agent C is an alcohol selected from a primary alcohol.

[0053] According to one embodiment, the chain capping agent C is an alcohol selected from a saturated or unsaturated polyol having 2 to 6 hydroxyl groups. As examples, the following polyols can be mentioned, such as glycerol, pentaerythritol, sorbitol or 1,4-butanediol.

[0054] According to one embodiment, the chain capping agent C is an alcohol having a pKa of 10 to 16, preferably a pKa of 12 to 16, preferably a pKa of 14 to 16.

[0055] According to one embodiment, the chain end-capper C is an alcohol selected from the group consisting of methanol (CAS 67-56-1), ethanol (CAS 64-17-5), propanol (CAS 71-23-8), isopropanol (CAS 67-63-0), butanol (CAS 71-36-3), allyl alcohol (CAS 107-18-6), benzyl alcohol (CAS 100-51-6), 3-buten-1-ol (627-27-0), an alcohol with long alkyl chains such as undecanol (CAS 112-42-5) or dodecanol (CAS 27342-88-7).

[0056] Preferably, the chain end-capper is benzyl alcohol (CAS 100-51-6), butanol (CAS 71-36-3) or 3-buten-1-ol (627-27-0).

[0057] Alternatively, within the scope of the present application, the chain end-capper C has at least one silanol terminal functional group.

[0058] Preferably, the chain end-capper C with a silanol terminal functional group is trimethylsilanol (CAS 1066-40-6), triethylsilanol (CAS 597-52-4) or a mixture thereof.

[0059] According to another embodiment of the present application, the chain end-capper C has at least one siloxy unit.

[0060] According to another embodiment, the chain end-capper C with a silanol terminal chemical functional group has at least two siloxy units. Alternatively, the chain end-capper C with a silanol terminal functional group has at least three siloxy units.

[0061] The term "silanol terminal functional group" is understood to mean a chemical functional group at the end of the chain formed by a chemical bond between a silicon atom and a hydroxyl group.

[0062] According to one embodiment of the present application, the chain end-capper C is represented by formula (X): Formula X wherein, R 1 are identical or different, represent: - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted with a heteroatom O, N, S or halide, - an alkenyl group comprising from 2 to 6 carbon atoms, - a cycloalkyl group comprising from 5 to 10 carbon atoms, optionally substituted with a heteroatom O, N, S or halide, - a C6-C 18 aryl group, or - Hydroxyl group, R 2 If they are the same or different, it means: - An alkenyl group containing 2-6 carbon atoms, preferably vinyl. - Hydroxyl group (OH), or - A linear or branched alkyl group containing 1-12 carbon atoms, preferably 1-5 carbon atoms, optionally substituted with at least one heteroatom O, N, S or a halide such as a fluorine atom, for example 1-10 fluorine atoms, such as (C1-C5)alkyl-CF3, wherein the alkyl group is linear or branched; q is an integer from 0 to 20, preferably from 0 to 10, more preferably from 0 to 5, and the condition is that at least one group R 2 It is a hydroxyl group (OH).

[0063] According to one embodiment of the present invention, the chain end-capping agent C is represented by the above formula (X): in, R 1 If they are the same or different, it means: - A linear or branched alkyl group comprising 1-12 carbon atoms, preferably 1-8 carbon atoms, optionally substituted with heteroatoms O, N, S or halides. - Alkenyl groups containing 2-6 carbon atoms, - A cycloalkyl group containing 5-10 carbon atoms, optionally substituted with heteroatoms O, N, S or halides. - C6-C 18 aryl, or - Hydroxyl group, R 2 If they are the same or different, it means: - Hydroxyl group (OH), q is an integer ranging from 0 to 20, preferably from 0 to 10, and more preferably from 0 to 5.

[0064] In another embodiment, the chain end-capping agent C is represented by the above formula (X), wherein: R 1 They are the same, representing CH3. R 2 If they are the same or different, it means: - An alkenyl group containing 2-6 carbon atoms, preferably vinyl. - Hydroxyl group (OH), - Linear or branched alkyl groups containing 1-10 carbon atoms, preferably 1-5 carbon atoms, or - Optional replacement of C6-C 18 Aryl; q is an integer from 0 to 20, preferably from 0 to 10, more preferably from 0 to 5, and the condition is that at least one group R2 It is a hydroxyl group (OH).

[0065] In another embodiment, the chain end-capping agent C is represented by the above formula (X), wherein: R 1 They are the same, representing CH3. R 2 They are the same, meaning: - Hydroxyl group (OH), And q is an integer ranging from 0 to 20, preferably from 0 to 10, and more preferably from 0 to 5.

[0066] The chain-end agent C can be in a solvent. This is particularly advantageous to dissolve it in the reaction mixture. The solvent is especially a non-polar solvent, such as an organic solvent of the alkane or aromatic hydrocarbon type. Preferably, the solvent is selected from pentane, n-hexane, n-heptane, n-decane, n-dodecane, isododecane, EXXSOL D60, xylene, toluene, and mixtures thereof.

[0067] Alternatively, the chain-end-capping agent C can be used in polar solvents such as THF, Me-THF, or CH2Cl2.

[0068] These chain-end-capping agents enable the functionalization of linear organopolysiloxanes (OL) during the polymerization reaction. Therefore, linear organopolysiloxanes (OL) with, for example, the same or different terminal chemical functional groups can be obtained.

[0069] According to one embodiment, the method of the present invention is characterized in that, in step a), the molar ratio of the chain end-capping agent C to the basic catalyst B is 0.01 to 600, preferably 0.8 to 300, preferably 1.5 to 300, preferably 4 to 200, and more preferably 8 to 100.

[0070] According to one embodiment, the method of the present invention is characterized in that, in step a), the molar ratio of the cyclic organopolysiloxane OC to the chain end-capping agent C is 1 to 20,000, preferably 2 to 5,000, preferably 2 to 1,400, preferably 4 to 700, more preferably 4 to 300, and even more preferably 10 to 150.

[0071] According to one embodiment of the present invention, the linear organopolysiloxane OL is a compound of formula (XI): Formula XI in, R is the same or different, indicating: - An alkyl group containing 1-15 carbon atoms, preferably 1-12 carbon atoms, preferably 1-10 carbon atoms, preferably 1-5 carbon atoms, preferably methyl. - An aryl group containing 6-10 carbon atoms, preferably phenyl. R 1 are identical or different and denote: - an alkyl group comprising 1 to 5 carbon atoms, - an alkenyl group comprising 2 to 6 carbon atoms, preferably vinyl, - a hydroxyl group (OH), or - a C6-C 18 aryl group, preferably phenyl, R 2 are identical or different and denote: - an alkenyl group comprising 2 to 6 carbon atoms, preferably vinyl, - a hydroxyl group (OH), - a linear or branched alkyl group comprising 1 to 12 carbon atoms, preferably 1 to 5 carbon atoms, optionally substituted by at least one heteroatom O, N, S or halide such as a fluorine atom, for example 1 to 10 fluorine atoms, for example (C1-C5)alkyl-CF3, the alkyl group being linear or branched, - a C5-C 10 cycloalkyl group, optionally substituted, - a C6-C 18 aryl group, optionally substituted, - a group (O-R 3 ), wherein R 3 denotes: an alkyl group comprising 1 to 15 carbon atoms, preferably 1 to 12 carbon atoms, preferably 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, preferably OCH3or OC2H5, an alkenyl group comprising 2 to 15 carbon atoms, preferably 2 to 10 carbon atoms, a C6-C 18 aryl group or an alkylaryl group such as benzyl, q is an integer from 0 to 50, preferably from 0 to 20, more preferably from 0 to 10; preferably, q = 0 n2 denotes an integer from 10 to 25 000, preferably from 10 to 5 000, preferably from 10 to 1 500, preferably from 50 to 1 000, more preferably from 100 to 500; m2 denotes an integer from 0 to 100, preferably from 0 to 50, more preferably from 0 to 30, preferably, m2 = 0.

[0072] According to a preferred embodiment of the application, the linear organopolysiloxane OL is a compound of formula (XI): wherein, R is identical or different and denotes CH3or phenyl, preferably CH3; R 1 are identical or different and denote: - an alkyl group comprising 1 to 5 carbon atoms, alkenyl comprising 2 to 6 carbon atoms, preferably vinyl, - C6-C 18 aryl, preferably phenyl, R 2 are identical or different and denote: - alkyl comprising 1 to 6 carbon atoms, - alkenyl comprising 2 to 6 carbon atoms, preferably vinyl, - hydroxyl (OH), - C6-C 18 aryl, - a group (O-R 3 ), wherein R 3 denotes: alkyl comprising 1 to 10 carbon atoms, alkenyl comprising 2 to 10 carbon atoms, or benzyl, q is an integer from 0 to 50, preferably from 0 to 20, more preferably from 0 to 10, preferably q = 0 n2 denotes an integer from 10 to 1500, preferably from 10 to 1000, preferably from 50 to 1000, more preferably from 100 to 500; m2 denotes an integer from 0 to 500, preferably from 0 to 100, more preferably from 0 to 50.

[0073] According to a particularly preferred embodiment of the application, the linear organopolysiloxane OL of the application is a compound of formula (XI), wherein

[0074] R is identical or different and denotes CH3or phenyl, preferably CH3, R 1 are identical or different and denote CH3, phenyl or vinyl; R 2 are identical or different and denote: - alkenyl comprising 2 to 6 carbon atoms, preferably vinyl, - hydroxyl (OH), - linear or branched alkyl comprising 1 to 10 carbon atoms, preferably 1 to 5 carbon atoms, - optionally substituted C6-C 18 aryl, or - a group (O-R 3 ), wherein R 3 denotes: alkyl comprising 1 to 10 carbon atoms, alkenyl comprising 2 to 10 carbon atoms, or benzyl, q is equal to 0; n2 represents an integer from 10 to 1500, preferably from 10 to 1000, preferably from 50 to 1000, more preferably from 100 to 500; m2 represents an integer from 0 to 500, preferably from 0 to 100, more preferably from 0 to 50.

[0075] According to one embodiment of the application, the linear organopolysiloxane OL of the application, as represented above by formula (XI), is one in which R 2 The same compound. In other words, the linear organopolysiloxane OL is homotéléchélique.

[0076] As a reminder, the term "homotéléchélique linear organopolysiloxane OL" is understood to mean a linear organopolysiloxane having the same terminal chemical functions.

[0077] Similarly, according to one embodiment of the application, the linear organopolysiloxane OL of the application, as represented above by formula (XI), is one in which R 2 A different compound. In other words, the linear organopolysiloxane OL is hétérotéléchélique.

[0078] As a reminder, the term "hétérotéléchélique linear organopolysiloxane OL" is understood to mean a linear organopolysiloxane having different terminal chemical functions.

[0079] In the meaning of the present application, the mass-average molar mass and the number-average molar mass (respectively denoted M w and M n ) of the various linear organopolysiloxanes OL can be determined by size exclusion chromatography (SEC) in the presence of polystyrene standards in a solvent such as toluene at 35°C.

[0080] According to one embodiment of the process of the application, the linear organopolysiloxane OL of the application is characterized in that its degree of polymerization is between 5 and 28000, preferably between 5 and 7000, preferably between 5 and 4000, preferably between 15 and 2000, more preferably between 20 and 1000, even more preferably between 20 and 400.

[0081] According to one embodiment of the process of the application, the linear organopolysiloxane OL of the application is characterized in that its mass-average molar mass M w may be between 500 and 2000000 g / mol, preferably between 500 and 500000 g / mol, preferably between 500 and 300000 g / mol, preferably between 1000 and 150000 g / mol, more preferably between 1000 and 100000 g / mol, even more preferably between 5000 and 40000 g / mol.

[0082] According to one embodiment of the process of the application, the linear organopolysiloxane OL of the application is characterized in that its number average molar mass M n between 500 and 2000000 g / mol, preferably between 500 and 500000 g / mol, preferably between 500 and 300000 g / mol, preferably between 1000 and 150000 g / mol, more preferably between 1000 and 100000 g / mol, even more preferably between 5000 and 40000 g / mol.

[0083] According to one embodiment of the process of the application, the linear organopolysiloxane OL of the application is characterized in that its dynamic viscosity is between 100 and 1000000 mPa.s at 25°C, preferably between 1000 and 500000 mPa.s at 25°C, preferably between 1000 and 100000, even more preferably between 10000 and 80000 mPa.s at 25°C.

[0084] Within the scope of the present application, the mass or weight percentage of D4 of the product obtained according to the process of the application can be measured via quantification 29 of the Si NMR spectrum. Alternatively, the mass or weight percentage of D4 of the product obtained according to the process of the application can be measured by the chromatogram resulting from the analysis by size exclusion chromatography (SEC).

[0085] Hereinafter, by product resulting from the reaction is meant the sum of the linear organopolysiloxane OL and of the cyclic organopolysiloxane OC resulting from the process of the application.

[0086] In one embodiment, the process according to the application is characterized in that the content of cyclic organopolysiloxane OC is less than 2%, preferably less than or equal to 1%, preferably less than or equal to 0.5%, relative to the total mass of the product resulting from the reaction.

[0087] In one embodiment, the process according to the application is characterized in that the content of octamethylcyclotetrasiloxane (D4) is less than 2%, preferably less than or equal to 1%, preferably less than or equal to 0.5%, relative to the total mass of the product resulting from the reaction.

[0088] Preferably, the process of the application is implemented without using any solvent, except for the amount necessary for solubilizing and / or dissolving the catalyst B in the reaction medium.

[0089] This embodiment is particularly advantageous as it makes it possible to avoid the use of solvents and their handling or recycling once used, while still providing satisfactory results when implementing the process of the application.

[0090] However, in an alternative embodiment, the process of the application is carried out in a non-polar solvent. This solvent can in particular be an organic solvent of the alkane, aromatic hydrocarbon type.

[0091] Preferably, the solvent is chosen from n-hexane, n-heptane, n-decane, n-dodecane, isododecane, EXXSOL D60, xylene, toluene and mixtures thereof.

[0092] Alternatively, the process of the application is carried out in a polar solvent. This solvent can in particular be an organic solvent such as THF or Me-THF.

[0093] In one embodiment, the process of the application is characterized in that the mass ratio of the cyclic organopolysiloxane OC relative to the mass of the solvent used is between 0.5 and 50, preferably between 1.5 and 15, preferably between 3 and 10, relative to the mass of the solvent used.

[0094] Advantageously and preferably, the reaction is carried out at a temperature of between 25°C and 150°C, preferably between 35°C and 100°C, more preferentially between 35°C and 80°C.

[0095] According to the process of the application, the duration of the reaction is between 1 minute and 48 hours, preferably between 1 minute and 18 hours, more preferentially between 1 minute and 8 hours, even more preferentially between 1 minute and 2 hours, even more preferentially between 1 minute and 1 hour.

[0096] The person skilled in the art will know how to adapt these parameters depending on the nature of the reactor and of the substances used.

[0097] The process as defined according to the application can also comprise a step b) by subsequently adding to the composition S which can be polymerized by ring-opening, a chain-stoppering agent C which is the same as or different from the chain-stoppering agent of step a) or an acid A.

[0098] Step b) of the process of the application makes it possible to provide flexibility in controlling the nature of the terminal chemical functions of the product OL and in controlling the molar mass of the product OL.

[0099] Indeed, depending on the nature of step b) of the process, it is possible to obtain linear organopolysiloxanes OL which are homo- or hetero-terminal.

[0100] As a reminder, by "linear organopolysiloxane OL which is homo-terminal" is understood a linear organopolysiloxane having the same terminal chemical functions.

[0101] By "linear organopolysiloxane OL which is hetero-terminal" is understood a linear organopolysiloxane having different terminal chemical functions.

[0102] According to an embodiment of the application, the method further comprises a step b) defined by the subsequent addition of a chain-stoppering agent C which is different from the chain-stoppering agent introduced during step a) of the method.

[0103] This embodiment makes it possible to obtain linear organopolysiloxanes OL with homoterminal groups while controlling the molar mass of the product thus obtained.

[0104] According to an embodiment of the application, the method further comprises a step b) defined by the subsequent addition of a chain-stoppering agent C which is different from the chain-stoppering agent introduced during step a) of the method.

[0105] This embodiment makes it possible to control both the molar mass of the product OL and the nature of the terminal chemical functions. Linear organopolysiloxanes OL with heteroterminal groups are thus obtained.

[0106] According to an embodiment of the application, the process according to the application is characterized in that the molar ratio of chain-stoppering agent C relative to basic catalyst B (used during step b)) is between 1 and 200, preferably between 1 and 100, preferably between 20 and 100.

[0107] According to an embodiment of the application, the process according to the application is characterized in that the molar ratio of cyclic organopolysiloxane OC relative to chain-stoppering agent C (used during step b)) is between 1 and 100, preferably between 5 and 80, preferably between 10 and 50.

[0108] Alternatively, step b) of the process according to the application comprises the step of subsequently adding an acid A to the composition S which is polymerizable by ring-opening polymerization.

[0109] This step b) makes it possible to neutralize the basic catalyst B and to stop the polymerization reaction carried out according to the process according to the application.

[0110] This embodiment also makes it possible to control the nature of the terminal chemical functions of the product OL. Linear organopolysiloxanes OL with heteroterminal groups are thus obtained.

[0111] According to an embodiment of the process according to the application, the acid A introduced during step b) of the process is chosen from acids such as organic acids, Lewis acids, functionalized organohalosilanes, ion exchange resins or mineral acids.

[0112] As regards organic acids, carboxylic acid derivatives such as propionic acid, glycolic acid, valeric acid, butyric acid, caproic acid, caprylic acid, capric acid, caprylic acid, lauric acid, myristic acid, stearic acid, palmitic acid, oleic acid, undecylenic acid or other carboxylic acid derivatives can in particular be mentioned.

[0113] Preferably, the acid A is chosen from carboxylic acid derivatives or mineral polyacids.

[0114] In the meaning of the present application, the term "mineral polyacid" means a compound formed of hydrogen and one or more other elements (except carbon) which has the ability to release a plurality of protons in aqueous solution, unlike monoacids which can only release one proton. Examples that can be mentioned include phosphoric acid, sulfuric acid and oxalic acid ions.

[0115] According to one embodiment of the present application, the acid A is phosphoric acid.

[0116] According to one embodiment of the present application, the acid A has a pKa of between 1 and 13, preferably between 1.5 and 10, preferably between 2 and 8.

[0117] Obviously, the person skilled in the art will know how to adapt the nature and the quantity of the acid A introduced to meet the requirements of the process of the application.

[0118] According to one particular embodiment, step b) of the process of the application comprises a step of adding to the composition S which can be polymerized by ring-opening a chain-stoppering agent C which is the same as or different from the chain-stoppering agent of step a) and an acid A.

[0119] According to one embodiment of the process of the application, step b) is carried out between 2 and 45 minutes after step a) of the process, preferably between 2 and 30 minutes, preferably between 2 and 15 minutes after step a) of the process.

[0120] During step c) of the process of the application, a linear organopolysiloxane OL is obtained.

[0121] This step c) can also comprise one or more filtration, evaporation, distillation steps to make it possible to obtain the linear organopolysiloxane OL.

[0122] The person skilled in the art will know how to adapt the implementation of these treatment steps and their operating conditions to meet the requirements of the process of the application.

[0123] The present application also relates to the linear organopolysiloxane OL obtained according to the various embodiments of the process of the application described above. The present application also relates to a silicone composition comprising the organopolysiloxane OL obtained according to the various embodiments of the process of the application described above.

[0124] The present application also relates to a composition S1 comprising: i) at least one cyclic organopolysiloxane OC having three siloxane units, ii) at least one basic catalyst B of formula (XII): Formula XII in which: - R1, which are identical or different, represent an alkyl chain having between 1 and 6 carbon atoms, preferably between 1 and 3 carbon atoms, - R2 represents a hydrogen atom or a group -C(=0)-R3, in which R3 represents an alkyl group having from 1 to 12 carbon atoms; - X represents an anion chosen from the group comprising carboxylate and its derivatives, carbonate and its derivatives, hydroxyl, siloxanolate, silanolate, and n is a natural integer between 1 and 6, iii) at least one chain capping agent C.

[0125] According to one embodiment of the application, the present application also relates to a composition S1 comprising: i) at least one cyclic organopolysiloxane OC having three siloxane units, ii) at least one basic catalyst B of formula (XIII): Formula XIII in which: - R1, which are identical or different, represent an alkyl chain having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, - X represents an anion chosen from the group comprising carboxylate and its derivatives, carbonate and its derivatives, hydroxyl, siloxanolate, silanolate, and n is a natural integer between 1 and 6 The present application also relates to the use of the organopolysiloxane OL obtained according to the process of the application as an ingredient which can be directly used in various silicone formulations which can be used, for example, in the fields of cosmetics, household maintenance products, automobiles, energy.

[0126] Finally, the present application relates to a basic catalyst B represented by formula (XIV): Formula XIV in which: - R1, which are identical or different, represent an alkyl chain having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, - X represents a siloxanolate or silanolate anion, and n is a natural integer between 1 and 6.

[0127] Preferably, the basic catalyst B represented by the above formula (XIV): in which: - R1, which are identical or different, represent an alkyl chain having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms, - X represents a silanolate anion, and n is a natural integer between 1 and 6.

[0128] Basic catalyst B represented by the formula (XIV) above: wherein: - R1, which are identical or different, represent an alkyl chain having 1 or 2 carbon atoms, - X represents a trimethylsilanol or triethylsilanol anion, and n is equal to 1. DETAILED DESCRIPTION

[0129] Examples : Cyclic organopolysiloxanes used in the examples : Cyclic organopolysiloxane OC1 : hexamethylcyclotrisiloxane (CAS 541-05-9) Cyclic organopolysiloxane OC2: 2,4,6-trivinyl-2,4,6-trimethylcyclotrisiloxane (CAS 3901-77-7) Comparative cyclic organopolysiloxane OC comp1 : octamethylcyclotetrasiloxane (CAS 556-67-2) Basic catalysts B used in the examples : Catalyst B1 : commercial choline hydroxide (CAS 123-41-1) diluted in water or methanol

[0130] Catalyst B2: trimethylsilanol choline (13%) diluted in 1,3-butene-1-ol (CAS 627-27-0), synthesized within the scope of the application.

[0131]

[0132] Catalyst B3: trimethylsilanol triethyicholine (13%) diluted in 1,3-butene-1-ol (CAS 627-27-0), synthesized within the scope of the application.

[0133]

[0134] Catalyst B4: choline bicarbonate (CAS 78-73-9)

[0135] Catalyst B5: choline salicylate (CAS 2016-36-6)

[0136] Catalyst B comp1 : triazabicyclodecene CAS (5807-14-7)

[0137] Catalyst B comp2 : KOSiMe3(CAS 10519-96-7) diluted in 1,3-butene-1 -ol (CAS 627-27-0), (13 mass%)

[0138] Catalyst B comp3 : KOSiMe3(CAS 10519-96-7)

[0139] Catalyst B comp4 : Choline chloride (CAS 67-48-1 )

[0140] Catalyst B comp5 : Tetramethylammonium hydroxide (CAS 75-59-2)

[0141] Chain capping agents used in the examples : Chain capping agent C comp1 : Divinyltetramethyldisiloxane (CAS 2627-95-4).

[0142] Chain capping agent C1 : Benzyl alcohol (CAS 100-51 -6)

[0143] Chain capping agent C2: 1,3-butene-1 -ol (CAS 627-27-0)

[0144] Chain capping agent C3: Triethylsilanol (CAS 597-52-4)

[0145] Chain capping agent C4: Trimethylsilanol (CAS 1066-40-6)

[0146] Chain capping agent C5: H2O

[0147] Chain capping agent C6: n-Butanol (CAS 71 -36-3)

[0148] The residual mass percentage of the cyclic organopolysiloxane OC (D3 or D4, D5 and D6) and the mass percentage of the linear organopolysiloxane OL obtained according to the process of the application, within the scope of the examples described below, are measured by size exclusion chromatography (SEC) in the presence of polystyrene standards in a solvent such as toluene at 35°C.

[0149] Likewise, the number average molar mass (expressed as M n ) of the various linear organopolysiloxanes OL according to the application is measured by the same method of size exclusion chromatography (SEC).

[0150] Example 1 : Synthesis of catalysts B2 and B3 : A solution of choline chloride or ethyl choline chloride (1.2 equivalents, dissolved in 3-buten-1-ol, 15 mass%) and a solution of potassium silanolate (1.0 equivalent, dissolved in 3-buten-1-ol, 25 mass%) were weighed into a 100 mL round bottom flask.

[0151] The resulting turbid reaction medium was mixed with magnetic stirring at ambient temperature for 2 hours. After filtration, catalyst B2 or B3 was obtained as a clear solution in 3-buten-1-ol at 13% by weight.

[0152] Example 2: General operating procedure for the polymerization process as defined according to the invention : The cyclic organopolysiloxane OC, the basic catalyst B and the chain capping agent C were introduced under inert atmosphere (argon) into a 500 mL reactor. The reaction mixture was maintained at 70°C for 1 hour under stirring. Samples were extracted and analyzed by 1 H NMR and 29 Si NMR.

[0153] Example 3a: Screening of different basic catalysts B to implement the process of the invention : In this example, the reaction mixture consisted of the cyclic organopolysiloxane OC1 (10 g), the basic catalyst B (5-9 mg) and the chain capping agent (with an OC / C ratio of 15 or an OC / C ratio of 21). For the whole of this example, the chain capping agent C was 1,3-buten-1-ol (CAS 627-27-0) (C2). The reaction mixture was maintained at 70°C under stirring. Samples were extracted and analyzed by 1 H NMR and 29 Si NMR.

[0154] The nature of the catalyst B, the reaction time, the molar quantity of catalyst B and the various products obtained at the end of the ring-opening polymerization are mentioned in Table 1 below.

[0155]

[0156] The additional tests were repeated with an OC / C molar ratio equal to 15.

[0157]

[0158] Concerning the calculation of the molar ppm of catalyst B, it is obtained according to the following calculation:

[0159] The above table shows that the basic catalyst B of the process of the application makes it possible to carry out a ring-opening polymerization with a maximum conversion in 10 to 30 minutes with a low amount of by-products (in this case residual cyclic compounds).

[0160] In the remainder of these examples, these by-products will be collectively referred to as residual OC. It should be noted that the only satisfactory comparative catalyst (B Comp5 ) is a catalyst that is toxic and ecotoxic, unlike those of the application.

[0161] Example 3b: In cyclic organopolysiloxane OC comp1 Comparative Example in the presence of : In a first example, the reaction mixture consists of a comparative cyclic organopolysiloxane OC comp1 (octamethylcyclotetrasiloxane) and a basic catalyst B1 (in the presence of C5).

[0162] In this example, the reaction mixture is maintained at a temperature of 70°C under stirring for one hour. Samples are collected and analyzed by 1 H NMR and 29 Si NMR.

[0163] Under the above conditions, 12% of product OL (88% OC comp1 ) is obtained.

[0164] A second test is carried out with a reaction mixture comprising a comparative cyclic organopolysiloxane OC comp1 (octamethylcyclotetrasiloxane), a catalyst B2 and a chain-stopper C2 (OC / C ratio of 21).

[0165] In this example, the reaction mixture is maintained at a given temperature under stirring. Samples are collected and analyzed by 1 H NMR and 29 Si NMR.

[0166] At 70°C, using catalyst B2, the yield after 4 hours of reaction is 0%.

[0167] If the experiment is repeated with B2 and the reaction medium is heated at 135°C for 4 hours, 10% of product OL (and 90% of OC comp1 ) is obtained.

[0168] Example 4: Influence of the nature of the chain capping agent C on the process of the invention : The operating procedure of example 2 is carried out using a cyclic organopolysiloxane OC1 (250 g), a basic catalyst B1 (950 pmol) and a chain-stopper C (52.7 mmol). The reaction mixture is maintained at 70°C under stirring for 1 hour. The molar ratio of OC1 / C is equal to 21.

[0169] The table below mentions the properties of the chain-stopper, the molar mass of the linear organopolysiloxane OL obtained and the mass percentage of residual cyclic organopolysiloxane OC resulting from the process of the application.

[0170]

[0171] Test 1 shows that traditional chain end-capping agents such as C comp1 Adjusting the molecular weight of the obtained product is not permitted. Furthermore, it can be observed that the percentage of cyclic byproducts (residual cyclic organopolysiloxanes OC) is higher than the percentage obtained under the conditions of the method claimed in this invention.

[0172] In particular, the presence of the chain-capping agent C in tests 2 to 5, as claimed by the method according to the invention, provides a very low content of cyclic byproducts (≤1%). Furthermore, these chain-capping agents allow for adjustment of the molar mass of the obtained product OL and control of the properties of the terminal chemical functional groups. Therefore, the results shown in the table above demonstrate that the method of the invention is universal and can be used with different chain-capping agents C as defined according to the invention.

[0173] Example 5: Influence of the amount of chain capping agent C on the process of the invention : Within the scope of this embodiment, the operating procedure of Example 2 was performed using cyclic organopolysiloxane OC1 (250 g), basic catalyst B1 (950 μmol), and chain-end-capping agent C4 (amounts defined in the table below). The reaction mixture was maintained at 70°C for 1 hour with stirring.

[0174] The table below mentions the molar ratio of OC1 to C, as well as the molecular weight of the obtained product OL and the mass percentage of the residual cyclic organopolysiloxane OC produced by the method of the present invention.

[0175]

[0176] The amount of chain-end agent C introduced into the reaction mixture allows control over the molecular weight of the obtained linear product OL.

[0177] Example 6: Preparation of organopolysiloxanes with homotelechelic or heterotelechelic groups

[0178] Within the scope of this embodiment, the procedures of Example 2 were performed using cyclic organopolysiloxane OC1 (250 g), basic catalyst B1 (950 μmol), and chain-end-capping agent C4 (52.7 mmol). The reaction mixture was maintained at 70°C with stirring for a period ranging from several minutes to 1 hour. Samples were then extracted and used... 1 H NMR and 29 Si NMR analysis. In this embodiment, the initial molar ratio OC1 / C was the same and equal to 21 for each test.

[0179]

[0180] The different steps of the method of the present invention are performed in the tests mentioned in the table above.

[0181] First, test 1 comprises only step a) of the process of the application. This test makes it possible to obtain a linear organopolysiloxane OL of identical end groups.

[0182] As a reminder, the term "linear organopolysiloxane OL of identical end groups" is understood to mean a linear organopolysiloxane having identical terminal chemical functions.

[0183] Test 2 comprises steps a) of the process of the application and optional step b) of the process. Within the scope of this example, step b) consists in the subsequent addition of the same chain-stopper C4. For test 2, the subsequent addition of the chain-stopper C4 is performed after a few minutes of reaction (8 to 15 minutes). Thus, a linear organopolysiloxane OL of identical end groups is obtained. This implementation (test 2) allows to control the molar mass of the product OL.

[0184] Finally, test 3 comprises step a) of the process of the application followed by step b) of the process. For this test, step b) consists in the addition of an acid (H3PO4) which makes it possible to obtain Heterotelechelic linear organopolysiloxane OL .

[0185] Thus, these different strategies detailed in the above table allow to influence the nature of the terminal chemical functions of the linear organopolysiloxane OL obtained depending on the nature of the reaction inhibition (addition of a second chain-stopper or addition of an acid to the reaction medium). The various 1 H NMR and 29 Si NMR spectra confirm these results.

[0186] Example 7: Preparation of short a, w-hydroxypolydimethylsiloxanes in a solvent medium : Within the scope of this example, the operating procedure of example 2 is performed with a cyclic organopolysiloxane OC1 (250 g), a basic catalyst B1 (950 pmol) and a chain-stopper C5 (52.7 mmol).

[0187] To obtain an a, w-hydroxypolydimethylsiloxane oil having a low number average molar mass M n of 6900 g / mol and a mass percentage of residual cyclic organopolysiloxane OC of 1.2%, the chain-stopper C is mixed with a solvent such as Me-THF (80 mL) and the reaction mixture is heated to 45°C. The sample is collected and analyzed by 1 H NMR and 29 Si NMR.

[0188] Under these operating conditions, a linear organopolysiloxane OL containing two hydroxyl functions at the end of the chain, having a number average molar mass M n of 6900 g / mol and a mass percentage of residual cyclic organopolysiloxane OC of 1.2%, is obtained.

[0189] This test demonstrates the flexibility of the process of the application and the possibility of obtaining a-, w-hydroxypolydimethylsiloxane oils with low number average molar mass M n

[0190] Block copolymers : Characterization of the V and D triades of the copolymers by NMR : By 29 Microstructural analysis by Si NMR is an extremely effective analytical tool for determining the structure and microstructure of linear organopolysiloxanes OL. This makes it possible to distinguish between D units and V units respectively resulting from the homopolymerization of the introduced cyclic organopolysiloxanes OC1 and OC2.

[0191] Thus, the distribution of V units in the silicone chain is determined from the distribution of the triads V V V, D V V (or V V D) and D V D. These triads are clearly identified by Si NMR by the presence of characteristic triplets of V V V, D V V (or V V D) and D V D units. 29 As a reminder, for the purposes of the present application, the triads V V V, D V V (or V V D) and D V D refer to the following units: V V V triad:

[0192] D V V (or V V D) triad:

[0193] D V D triad:

[0194] The D D D, D D V and V D V triads will be composed in a similar manner.

[0195] Within the scope of the present embodiment, the term "statistical product" refers to a linear organopolysiloxane OL having a random distribution of vinyl units (V) obtained by the process of the application.

[0196] On the other hand, for the purposes of the present application, the term "block copolymer" refers to a linear organopolysiloxane OL having a non-random distribution of vinyl units (V) obtained according to the process of the application.

[0197] Within the scope of the present embodiment, the process of the application is carried out in six different embodiments: ​The cyclic organopolysiloxane OC, the basic catalyst B (800 ppm) and the chain capping agent C were introduced into a vial under inert atmosphere (argon). The reaction mixture was maintained at 70°C for a period of 1 hour under stirring. The sample was collected and analyzed with 1 H NMR and 29 Si NMR analysis.

[0198] In the context of the various tests A, B and C described below, the cyclic organopolysiloxane introduced was OC1 (5 g, 70 mol%) and OC2 (2.5 g, 30 mol%). The basic catalyst B1 was dissolved in methanol and the chain capping agent was C4.

[0199] Test A : was performed using the cyclic organopolysiloxanes OC1 and OC2 introduced simultaneously.

[0200] Test B : was performed using the cyclic organopolysiloxane OC1 and the cyclic organopolysiloxane OC2 was introduced about ten minutes after the beginning of the reaction.

[0201] Test C : was performed using the cyclic organopolysiloxane OC2 and the cyclic organopolysiloxane OC1 was introduced about ten minutes after the beginning of the reaction.

[0202] In the context of the various tests D, E and F described below, the cyclic organopolysiloxane introduced was OC1 (5 g, 80 mol%) and OC2 (1.7 g, 20 mol%). The basic catalyst B1 was dissolved in water and the chain capping agent was C6.

[0203] Test D : was performed using the cyclic organopolysiloxanes OC1 and OC2 introduced simultaneously.

[0204] Test E : was performed using the cyclic organopolysiloxane OC1 and the cyclic organopolysiloxane OC2 was introduced about ten minutes after the beginning of the reaction.

[0205] Test F : was performed using the cyclic organopolysiloxane OC2 and the cyclic organopolysiloxane OC1 was introduced about ten minutes after the beginning of the reaction.

[0206]

[0207] Therefore, the experimental data measured under the conditions described above show a tendency to form block copolymers under these particular experimental conditions. Therefore, in addition to the control of the nature of the terminal chemical functions discussed in the foregoing examples, the process of the application also allows to control the structure of the linear organopolysiloxane OL obtained.

[0208] Characterization of the units present at the chain ends for tests A, B and C SUMMARY OF THE INVENTION DETAILED DESCRIPTION OF THE INVENTION Examples Cyclic organopolysiloxanes used in the examples Basic catalysts B used in the examples Chain capping agents used in the examples Example 1 : Synthesis of catalysts B2 and B3 Example 2: General operating procedure for the polymerization process as defined according to the invention Example 3a: Screening of different basic catalysts B to implement the process of the invention Example 4: Influence of the nature of the chain capping agent C on the process of the invention Example 5: Influence of the amount of chain capping agent C on the process of the invention Example 6: Preparation of organopolysiloxanes with homotelechelic or heterotelechelic groups Heterotelechelic linear organopolysiloxane OL Example 7: Preparation of short a, w-hydroxypolydimethylsiloxanes in a solvent medium Block copolymers Characterization of the V and D triades of the copolymers by NMR Test A Test B Test C Test D Test E Test F Characterization of the units present at the chain ends for tests A, B and C The above mentioned addition of chain end capping agent C4 29 The microstructure analysis by Si NMR also makes it possible to identify the units found at the chain end in tests A, B and C. In other words, this makes it possible to assess the possible influence of the order of addition of the cyclic organopolysiloxane OC on the nature of the units found at the chain end.

[0209] In the table below, the abbreviation HO-D represents the following unit:

[0210] The abbreviation (Me)3SiO-D represents the following unit:

[0211] Similarly, the abbreviation HO-V represents the following unit:

[0212] Finally, the abbreviation (Me)3SiO-V represents the following unit:

[0213] The results obtained are mentioned in the table below.

[0214]

[0215] Thus, using the chain end capping agent C4, a different distribution of the units present at the chain end is observed according to the embodiments of the process according to the application (tests A, B or C). In particular, the table above shows that the order of addition of the cyclic organopolysiloxane OC strongly influences the nature of the "terminal" units. Moreover, the chain end capping agent C4 allows complete control of the nature of the units present at the chain end.​

Claims

1. A method for preparing linear organopolysiloxane OL by ring-opening polymerization, the method comprising the following steps: a) Using a composition S that can be ring-polymerized, comprising: i) at least one cyclic organopolysiloxane (OC) having three siloxane units, ii) At least one basic catalyst B of formula (I): Formula I in: - R1 can be the same or different, representing an alkyl chain having 1-6 carbon atoms, preferably 1-3 carbon atoms. - R2 represents a hydrogen atom or a group -C(=O)-R3, where R3 represents an alkyl group having 1-12 carbon atoms; - X represents an anion selected from the group consisting of: carboxylate and its derivatives, carbonate and its derivatives, hydroxyl group, siloxane group, silanol group, - n is a natural integer between 1 and 6, and iii) At least one chain end-capping agent C, b) Optionally, a chain-end agent C or acid A, which is the same as or different from the chain-end agent used in step a), may then be added to the composition S, which can be polymerized by ring-opening polymerization. c) Obtain linear organopolysiloxane OL.

2. The method according to any one of the preceding claims, wherein the cyclic organopolysiloxane OC is represented by formula (II): Formula II in, R is the same or different, and it represents an alkyl group having 1-6 carbon atoms, an alkenyl group having 2-6 carbon atoms, or an aryl group having 6-18 carbon atoms.

3. The method according to any one of the preceding claims, wherein the alkaline catalyst B is represented by formula (III): Formula III in: - R1 indicates an alkyl chain having 1-6 carbon atoms, preferably 1-3 carbon atoms. - X represents an anion selected from the group consisting of: carboxylate and its derivatives, carbonate and its derivatives, hydroxyl group, siloxane group, silanol group, And n is a natural integer between 1 and 6.

4. The method according to any one of the preceding claims, wherein the molar amount of alkaline catalyst B is 150 ppm to 4000 ppm, preferably 250 to 2500 ppm, more preferably 250 ppm to 1500 ppm, relative to the molar amount of the reaction mixture.

5. The method according to any one of the preceding claims, wherein the chain-end agent C is selected from H2O or a compound of formula (VIII): Formula VIII in: Y represents a carbon atom or a silicon atom; R is the same or different and means: - Alkyl groups having 1-12 carbon atoms, - Cycloalkyl groups having 5-8 carbon atoms - Alkenyl groups with 2-12 carbon atoms containing 1-6 unsaturated carbon-carbon bonds. - An aryl group having 6-18 carbon atoms, preferably phenyl. - Benzyl, - Having at least 5, preferably at least 10, formulas R 1 c SiO (4-c) / 2 The silyloxy group of the unit in R 1 "Identical or different" indicates an alkyl group containing 1-15 carbon atoms, preferably 1-12 carbon atoms, preferably 1-10 carbon atoms, preferably 1-5 carbon atoms, preferably methyl; an aryl group containing 6-10 carbon atoms, preferably phenyl; and c = 0, 1, or 2; and The group R may be unsubstituted or substituted with an alkyl chain having 1-12 carbon atoms, an alkenyl group having 2-6 carbon atoms, a cycloalkyl group having 5-8 carbon atoms, an aryl group having 6-18 carbon atoms, or a heteroatom such as oxygen, sulfur, or nitrogen.

6. The method according to any one of the preceding claims, wherein the chain end-capping agent C is an alcohol or silanol having a pKa of 10-16, preferably 12-16, or preferably 14-16.

7. The method according to any one of the preceding claims, wherein in step a), the molar ratio of the chain end-capping agent C to the basic catalyst B is 0.01 to 600, preferably 0.8 to 300, preferably 1.5 to 300, preferably 4 to 200, and more preferably 8 to 100.

8. The method according to any one of the preceding claims, wherein in step a), the molar ratio of the cyclic organopolysiloxane OC to the chain end-capping agent C is 1 to 20,000, preferably 2 to 5,000, preferably 2 to 1,400, preferably 4 to 700, more preferably 4 to 300, and even more preferably 10 to 150.

9. The method according to any one of the preceding claims, wherein in step b), the molar ratio of the cyclic organopolysiloxane OC to the chain end-capping agent C used during that step is 1 to 100, preferably 10 to 80, and more preferably 10 to 50.

10. Composition S1, comprising: i) at least one cyclic organopolysiloxane (OC) having three siloxane units, ii) At least one basic catalyst B of formula (XII): Formula XII in: - R1 can be the same or different, representing an alkyl chain having 1-6 carbon atoms, preferably 1-3 carbon atoms. - R2 represents a hydrogen atom or a group -C(=O)-R3, where R3 represents an alkyl group having 1-12 carbon atoms; - X represents an anion selected from the group consisting of: carboxylate and its derivatives, carbonate and its derivatives, hydroxyl group, siloxane group, silanol group, And n is a natural integer between 1 and 6, and iii) At least one chain end-capping agent C.

11. Catalyst B represented by formula (XIV): Formula XIV in: - R1 can be the same or different, representing an alkyl chain having 1-6 carbon atoms, preferably 1-3 carbon atoms. - X represents a siloxane group or a siloxane anion. And n is a natural integer between 1 and 6.

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