Polymerization of Siloxane Polymers

Abstract

An improved process for the preparation of high viscosity (i.e., greater than 1 million mPa.s at 25° C.) silanol-terminated silicone polymers and copolymers, often referred to in the industry as silanol-terminated silicone polymer gums. The silanol-terminated silicone polymer gums are made by ring-opening polymerization of organocyclosiloxane oligomers (alternatively referred to as cyclic siloxane oligomers) using a conical screw dump extruder (1). The present invention also relates to the silanol-terminated silicone polymer gums made by this process.

Description

[Technical field]

[0001] The present invention relates to an improved process for the preparation of high viscosity (i.e., greater than 1 million mPa.s at 25° C.) silanol terminated silicone polymers and copolymers, often referred to in the industry as silanol terminated silicone polymer gums. The silanol terminated silicone polymer gums are made by ring-opening polymerization of organocyclosiloxane oligomers (alternatively called cyclic siloxane oligomers). The present invention also relates to the silanol terminated silicone polymer gums made by this process.

[0002] Organocyclosiloxane oligomers are formed by the hydrolysis of diorganodichlorosilanes and can be isolated by distillation. They are important intermediates in the silicone industry since they can be used as key building blocks in the preparation of silicone polymers and copolymers and their respective gums.

[0003] Each siloxane unit in the organocyclosiloxane typically has the following structure: -[(R' 2 )SiO]-

[0004] Each R' group is the same or different and is selected from alkyl, alkenyl, aryl, fluoroalkyl, such as trifluoropropyl, or perfluoroalkyl groups. Thus, the organocyclosiloxane oligomer can contain, for example, dimethylsiloxane units, methylvinylsiloxane units, trifluoroalkylmethylsiloxane units, such as trifluoropropylmethylsiloxane units, and / or phenylmethylsiloxane units within the ring.

[0005] Preferred organocyclosiloxane oligomers for use as polymeric building blocks typically have an average of 3 to 5 siloxane units in the organocyclosiloxane ring. Examples of suitable organocyclosiloxane oligomers are octamethylcyclotetrasiloxane, hexamethylcyclotrisiloxane, decamethylcyclopentasiloxane, cyclopenta(methylvinyl)siloxane, cyclotetra(phenylmethyl)siloxane, cyclopentamethylhydrosiloxane, trifluoropropylmethylcyclotrisiloxane, and mixtures thereof.

[0006] Typically, organocyclosiloxane oligomers and their mixtures, either alone or together with a suitably end-blocked polydiorganosiloxane, undergo a polymerization process that involves ring-opening of the organocyclosiloxane oligomer in the presence of a catalyst such as an acid or base. During the polymerization reaction, an equilibrium is created between the desired polymeric compound and the mixture of organocyclosiloxane compounds. The equilibrium obtained depends largely on the nature and number of organocyclosiloxane compounds, the catalyst used, and the polymerization process temperature. Such polymerization processes are generally carried out in the absence of solvent. Typically, end-blocking agents are used to add functionality and control the molecular weight of the resulting polymer.

[0007] For example, silicone polymers and copolymers containing fluoroalkyl groups, such as trifluoropropyl or perfluoroalkyl groups, include, for example: R 1 (R 2 ) 2 SiO-((R 4 )(R 3 )SiO) m -Si(R 1 )(R 2 ) (I) R 1 (R 2 ) 2 SiO-((R 4 )(R 3 )SiO) m -((R 2 ) 2 SiO)q Si(R 1 )(R 2 ) 2 (II) (In the formula, Each R 2 are the same or different and are saturated monovalent hydrocarbon groups such as alkyl, aryl, or alkaryl groups, fluoroalkyl groups, or perfluoroalkyl groups, Each R 1 is -OH, hydrogen, an alkenyl group, or an alkynyl group; Each R 3 is a fluoroalkyl group or a perfluoroalkyl group, Each R 4 is R 2 or an unsaturated monovalent hydrocarbon group such as an alkenyl group or an alkynyl group, where q and m are positive integers. The copolymer may be a random copolymer or a block copolymer.

[0008] Such silicone polymers and / or silicone copolymers include tri-(fluoropropylmethyl)tricyclosiloxane: ((CH 3 )(CH 2 CH 2 CF 3 )SiO) 3 and a suitable catalyst, such as an alkali metal hydroxide, an alkali metal alkoxide, or a complex of an alkali metal hydroxide and an alcohol; silanolates, such as alkali metal silanolates, phosphonitrile halides (sometimes called acid phosphazenes), phosphazene bases, and catalysts derived from the reaction of a tetraalkylammonium hydroxide with a siloxane tetramer as described in U.S. Pat. No. 3,433,765.

[0009] The viscosity of the resulting polymer can be controlled / limited using a suitable chain initiator / endblocker, e.g., water or a suitable short chain siloxane, such as a short chain silanol. After the polymerization reaction is complete, the catalyst can be quenched in a suitable manner and the remaining low molecular weight components can be removed, if desired.

[0010] Batch processes for making silicone polymer gums using the ring-opening polymerization process described above often use a kneader-type mixer to prepare the silicone polymer gum, and then transfer / discharge the resulting polymer into a second piece of equipment, such as a general-purpose or large hopper extruder for down packaging. However, transferring polymer materials between pieces of equipment can cause contamination and reliability issues, resulting in, for example, the need to discharge and scrape off residual materials between batches for reasons of changeover loss, requiring, for example, polytetrafluoroethylene (PTFE) filling and laborious cleaning steps. Furthermore, the need to transfer polymers between separate pieces of equipment can expose workers to potentially toxic materials.

[0011] 1. A process for producing a silanol terminated silicone polymer gum having a William's plasticity of at least 200 mm / 100 according to ASTM D-926-08, comprising carrying out a ring-opening polymerization of one or more organocyclosiloxane oligomers having 3 to 5 siloxane units per molecule, the siloxane units including dialkylsiloxane units, alkylalkenylsiloxane units, trifluoroalkylalkylsiloxane units, perfluoroalkylalkylsiloxane units, phenylalkylalkylsiloxane units, or mixtures thereof in the organocyclosiloxane ring, each alkyl group being the same or different and containing 1 to 10 carbons, and each alkenyl group being the same or different and containing 2 to 10 carbons, the ring-opening polymerization comprising (i) transporting one or more organocyclosiloxane oligomers having 3 to 5 siloxane units per molecule to a polymerization reactor heated to a predetermined temperature of 40 to 170° C. in an inert atmosphere; (ii) simultaneously with or subsequent to step (i), introducing a suitable -OH species containing chain initiator / endblocker into the polymerization reactor and mixing with the organocyclosiloxane oligomer, optionally removing residual water; (iii) introducing a catalyst suitable for catalyzing the ring-opening polymerization into the polymerization reactor to form a reaction mixture with the mixture obtained in step (ii) and subsequently proceeding to ring-open polymerization of the one or more organocyclosiloxane oligomers to produce a silicone polymer gum reaction product; (iv) quenching the silicone polymer gum reaction product resulting from step (iii) and, optionally, vacuum stripping the silicone polymer gum reaction product using vacuum means within the polymerization reactor; (v) cooling the silicone polymer gum reaction product resulting from step (iv) to form a final silicone polymer gum reaction product, and then carrying out either step (vi) or (vii), or both steps (vi) and (vii); (vi) transporting the final silicone polymer gum reaction product to a filling means for filling into suitable storage containers; (vii) transporting the final silicone polymer gum reaction product to a compounding means for combining the silicone polymer gum reaction product with other ingredients; Provided herein is a process characterized in that the polymerization reactor utilized is a conical screw dump extruder equipped with a conical twin chamber containing two counter-rotating conical screws converging towards an extrusion die having an inlet and an outlet, the passage through the extrusion die being controlled by a closure means such that the outlet of the extrusion die is configured to be closed by the closure means until the end of step (v) and open during steps (vi), (vii), or both (vi) and (vii), such that during polymerization the reaction mixture is driven by the pair of counter-rotating conical screws towards the extrusion die and then returned when the extrusion die is closed by the closure means and then extruded through the extrusion die during steps (vi), (vii), or both steps (vi) and (vii) and transported to a filling means and / or a compounding means, respectively.

[0012] There is also provided a silanol terminated silicone polymer gum having a William's plasticity number of at least 200 mm / 100 according to ASTM D-926-08 obtained or obtainable by the above process.

[0013] 1. Use of a conical screw dump extruder as a polymerization reactor in a process for producing a silanol terminated silicone polymer gum, the silanol terminated silicone polymer gum having a William plasticity of at least 200 mm / 100 according to ASTM D-926-08, comprising carrying out a ring-opening polymerization of one or more organocyclosiloxane oligomers having 3 to 5 siloxane units per molecule, the siloxane units comprising dialkylsiloxane units, alkylalkenylsiloxane units, trifluoroalkylalkylsiloxane units, perfluoroalkylalkylsiloxane units, phenylalkylalkylsiloxane units, or mixtures thereof in the organocyclosiloxane ring, each alkyl group being the same or different and containing 1 to 10 carbons, each alkenyl group being the same or different and containing 2 to 10 carbons, the ring-opening polymerization being (i) transferring one or more organocyclosiloxane oligomers having 3 to 5 siloxane units per molecule to a polymerization reactor heated to a predetermined temperature of 40 to 170° C. in an inert atmosphere; (ii) simultaneously with or subsequent to step (i), introducing a suitable -OH species containing chain initiator / endblocker into the polymerization reactor and mixing with the organocyclosiloxane oligomer, optionally removing residual water; (iii) introducing a catalyst suitable for catalyzing the ring-opening polymerization into the polymerization reactor to form a reaction mixture with the mixture obtained in step (ii) and subsequently proceeding to ring-open polymerization of the one or more organocyclosiloxane oligomers to produce a silicone polymer gum reaction product; (iv) quenching the silicone polymer gum reaction product resulting from step (iii) and, optionally, vacuum stripping the silicone polymer gum reaction product using vacuum means within the polymerization reactor; (v) cooling the silicone polymer gum reaction product resulting from step (iv) to form a final silicone polymer gum reaction product, and then carrying out either step (vi) or (vii), or both steps (vi) and (vii); (vi) transporting the final silicone polymer gum reaction product to a filling means for filling into suitable storage containers; (vii) transporting the final silicone polymer gum reaction product to a compounding means for combining the silicone polymer gum reaction product with other ingredients; Also provided herein is a use, characterized in that the polymerization reactor employed is a conical screw dump extruder equipped with a conical twin chamber, the conical twin chamber housing two counter-rotating conical screws converging towards an extrusion die having an inlet and an outlet, the passage through the extrusion die being controlled by a closure means, such that the outlet of the extrusion die is configured to be closed by the closure means until the end of step (v) and open during steps (vi), (vii), or both (vi) and (vii), such that during polymerization the reaction mixture is driven by the pair of counter-rotating conical screws towards the extrusion die, then returned when the extrusion die is closed by the closure means, and then extruded through the extrusion die during steps (vi), (vii), or both steps (vi) and (vii) and transported to a filling means and / or a compounding means, respectively.

[0014] It is understood that the present disclosure relates to a polymerization process that starts with a low viscosity organocyclosiloxane oligomer and does not combine multiple components to make a silicone-based or curable composition. The conical screw dump extruder is designed to intermix preformed polymers and fillers into a base material or compound with other components that are not intended for polymerization using the low viscosity organocyclosiloxane oligomer as the initial component.

[0015] the one or more organocyclosiloxane oligomers have 3 to 5 siloxane units per molecule in the organocyclosiloxane ring, including dialkylsiloxane units, alkylalkenylsiloxane units, trifluoroalkylalkylsiloxane units, perfluoroalkylalkylsiloxane units, phenylalkylalkylsiloxane units, or mixtures thereof; Each alkyl group is the same or different and contains 1 to 10 carbons, or the same or different and contains 2 to 10 carbons. Any suitable organocyclosiloxane oligomer or combination of said organocyclosiloxane oligomers having 3 to 5 siloxane units per molecule can be used in the process herein. Each siloxane unit in the organocyclosiloxane oligomer typically has the following structure: -[(R' 2 )SiO]-

[0016] Each R' group is the same or different and is selected from alkyl groups, alkenyl groups, aryl groups, fluoroalkyl groups such as trifluoropropyl, or perfluoroalkyl groups. Examples of suitable organocyclosiloxane oligomers include, but are not limited to, octamethylcyclotetrasiloxane, hexamethylcyclotrisiloxane, decamethylcyclopentasiloxane, penta-(methylvinyl)cyclopentasiloxane, tetra-(phenylmethyl)cyclotetrasiloxane, penta-(methylhydro)cyclopentasiloxane, tri-(methylvinyl)cyclotrisiloxane, tri-(ethylvinyl)cyclotrisiloxane, tetra-(methylvinyl)cyclotetrasiloxane, tetra-(ethylvinyl)cyclotetrasiloxane, penta-(methylvinyl)cyclopentasiloxane, and penta-(ethylvinyl)cyclopentasiloxane.

[0017] The organocyclosiloxane oligomers utilized in this process may contain fluoro-containing groups, including fluoroalkyl groups such as trifluoropropyl, trifluoroethyl, and nonafluorohexyl groups, as well as perfluoroalkyl groups such as:CF 3 -, C 2 F 5 -, C 3 F 7 -, e.g. CF 3 CF 2 CF 2 -or (CF 3 ) 2 CF-, C4 F 9 -, e.g. CF 3 CF 2 CF 2 CF 2 -, (CF 3 ) 2 CFCF 2 -, (CF 3 ) 3 C- and CF 3 CF 2 (CF 3 )CF-;C 5 F 11 , e.g. CF 3 CF 2 CF 2 CF 2 CF 2 -, C 6 F 13 -, e.g. CF 3 (CF 2 ) 4 CF 2 -;C 7 F 14 -, e.g. CF 3 (CF 2 CF 2 ) 3 -; and C 8 F 17 -.

[0018] Specific examples include tri-(fluoropropylmethyl)tricyclosiloxane, tri-(fluoropropylethyl)tricyclosiloxane, tetra-(fluoropropylmethyl)tetracyclosiloxane, tetra-(fluoropropylethyl)tetracyclosiloxane, penta-(fluoropropylmethyl)pentacyclosiloxane, penta-(fluoropropylethyl)pentacyclosiloxane, tri-(fluoroethylmethyl)tricyclosiloxane, tri-(fluoroethylethyl)tricyclosiloxane, tetra-(fluoroethylmethyl)tetracyclosiloxane, tetra-(fluoroethylethyl)tetracyclosiloxane, penta-(fluoroethylmethyl)pentacyclosiloxane, penta-(fluoroethylethyl)pentacyclosiloxane, and mixtures thereof.

[0019] Any suitable -OH species containing chain initiator / endcapping agent can be utilized to initiate the polymerization and / or end / cap the resulting silicone polymer gum.

[0020] The -OH species may be water, an alcohol, a glycol. Specific examples include straight or branched chain aliphatic alcohols having 2 to 10 carbons per molecule, including ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, isopropanol, isobutanol, 2-methyl-1-butanol, and 3-methyl-1-butanol, propylene glycol, ethylene glycol, and / or butylene glycol. Alternatively, the -OH species may be any suitable siloxane unit, such as (Me 2 Si-O) unit, (ViMeSi-O) unit, (MePHSi-O) unit, (Ph 2 The short chain organopolysiloxane may be a short chain organopolysiloxane having at least one -OH group per molecule and a degree of polymerization of 2 to 30, such as a disilanol or trisilanol, including (MeTFPSi-O) units, and (MeTFPSi-O) where TFP represents trifluoropropyl, or mixtures thereof. The short chain organopolysiloxane having at least one -OH group per molecule has an average degree of polymerization of 2 to 30, alternatively 3 to 25, including an average degree of polymerization of 5 to 25, per molecule. As specific examples, the -OH species containing chain initiator / endblocker may be: HO(MeTFPSi-O) d -H may also be used.

[0021] In the formula, the average value of d is an average degree of polymerization per molecule of 2 to 30, alternatively an average degree of polymerization of 2 to 25, alternatively an average degree of polymerization of 2 to 20, alternatively an average degree of polymerization of 2 to 15, alternatively an average degree of polymerization of 2 to 10, Me represents methyl, and TFP represents trifluoropropyl.

[0022] The catalyst used herein may be any catalyst suitable for catalyzing a ring-opening polymerization reaction, such as, for example, (I) a suitable alkaline catalyst, for example a suitable hydroxide such as potassium hydroxide, cesium hydroxide, or ammonium hydroxide, or a silanolate; (II) Suitable alkali metal alkyls, such as n-butyllithium, n-butylsodium, and n-butylpotassium; (III) ammonia; (IV) complexes of alkali metal alkoxides or alkali metal hydroxides with alcohols; (V) catalysts derived from the reaction of tetra-alkylammonium hydroxides with siloxane tetramers, as described in U.S. Pat. No. 3,433,765; (VI) Alkali metal-containing silanolates, such as potassium trimethylsilanolate ((CH 3 ) 3 -Si-O - K + ), lithium silanolates, and sodium silanolates, such as sodium trifluoropropylmethylsilanolate, having the following structure:

[0023] [ka] where, when added to the starting organocyclosiloxane oligomer, the initial average value of n is 3 to 6; (VII) Nonmetallic silanolates, for example Silanolates of alkyl ammonium hydroxide compounds, such as tetramethylammonium trimethylsilanolate [(CH 3 ) 4 N-OSi(CH 3 ) 3], tetraethylammonium trimethylsilanolate, tetrapropylammonium trimethylsilanolate, tetramethylammonium triethylsilanolate, tetraethylammonium triethylsilanolate, tetrapropylammonium triethylsilanolate, tetramethylammonium tripropylsilanolate, tetraethylammonium tripropylsilanolate, tetrapropylammonium tripropylsilanolate, etc.; (VIII) phosphazene bases. (A large number of phosphazene bases and their synthetic routes are described in the literature); and (IX) Transient silanolate catalysts such as ammonium trifluoropropylmethylsilanolate.

[0024] Typically, for such catalysts, except for the temporary catalyst (IX), the activity of the catalyst is quenched by using a neutralizing agent that reacts with the catalyst to inactivate it after the polymerization reaction is completed. Any suitable neutralizing agent may be utilized. These may include, for example, weak acids, such as weak Lewis acids, which are effective in neutralizing basic catalysts. Such neutralizing agents include, for example, phosphoric acid, tris(chloroethyl)phosphite silyl phosphate carbon dioxide, and NaH 2 PO 4 Or Na 2 HPO 4 The neutralizing agent may be selected from suitable buffers such as carbon dioxide, a weak Lewis acid that functions when used in conjunction with a silanolate catalyst. For example, if the catalyst used is sodium silanolate, the neutralizing agent typically reacts with the sodium silanolate to form sodium bicarbonate end groups and other sodium salts. Other neutralizing agents such as silyl phosphonates and fumed silica may be used alone or in combination with silanols. The selection of the neutralizing agent may improve the stripping of the gum product by improving the thermal stability of the gum.

[0025] In the case of the temporary catalyst (IX), instead of heating / cooling the polymerization reactor to a reaction temperature of 40-60°C in an inert atmosphere to allow the polymerization reaction to occur, and then introducing a neutralizing agent, the reaction mixture is quenched after completion of the polymerization process by heating the final product to a temperature of at least 80°C to generate ammonia gas, which is then removed from the polymer reactor under vacuum. This may have the advantage that the use of vacuum may help to remove at least some residual organocyclosiloxanes and by-products of the polymerization reaction using heat and vacuum in a conical screw dump extruder polymerization reactor.

[0026] The starting components for the polymerization reactions herein include greater than (>) 99.5% organocyclosiloxane oligomers along with appropriate levels of silanolate catalyst and -OH species containing chain initiator / endblocker.

[0027] The silanol terminated silicone polymer gums prepared by the process herein are generally linear or substantially linear, meaning that they contain less than 2.5% branching by weight, alternatively less than 1.5% branching by weight, alternatively less than 0.5% branching by weight, alternatively less than 0.1% branching by weight. The silanol terminated silicone polymer gums prepared by the process herein have a William's plasticity of at least 200 mm / 100 according to ASTM D-926-08. Silicone polymer gums (also known in the industry as organopolysiloxane polymer gums, silicone polymer gums, or siloxane gums) have very high viscosities (at least 1,000,000 mPa.s at 25° C., often several million mPa.s at 25° C.). Because it is difficult to measure the viscosity of such highly viscous fluids, silicone polymer gums tend to be defined by their William's plasticity (the ability of a sample to undergo compressive deformation under an external force and retain the deformation after the external force is removed) as opposed to their viscosity. Typically, the silicone polymer gum may have a William plasticity value of up to about 400 mm / 100 for fluorosilicone polymer gums measured according to ASTM D-926-08. Alternatively, the silanol terminated silicone polymer gums prepared by the process herein have a William plasticity of at least 225 mm / 100 according to ASTM D-926-08, or 250 mm / 100 according to ASTM D-926-08. Such plasticity values ​​ensure that the resulting polymer product can be extruded from the polymerization reactor without leaving traces of unextruded material in the conical screw dump extruder which must be cleaned between batches.

[0028] In the process herein, the following steps (a) to (e) are provided: (i) transporting one or more organocyclosiloxane oligomers having 3 to 5 siloxane units per molecule to a polymerization reactor heated to a predetermined temperature of 40 to 170° C. in an inert atmosphere; (ii) simultaneously with or subsequent to step (i), introducing a suitable -OH species containing chain initiator / endblocker into the polymerization reactor and mixing with the organocyclosiloxane oligomer, optionally removing residual water; (iii) introducing a catalyst suitable for catalyzing the ring-opening polymerization into the polymerization reactor to form a reaction mixture with the mixture obtained in step (ii) and subsequently allowing the ring-opening polymerization of the one or more organocyclosiloxane oligomers to proceed to produce a silicone polymer gum reaction product; (iv) quenching the silicone polymer gum reaction product resulting from step (iii) and optionally vacuum stripping the silicone polymer gum reaction product using vacuum means within the polymerization reactor; (v) cooling the silicone polymer gum reaction product resulting from step (iv) to form a final silicone polymer gum reaction product, and then carrying out either step (vi) or (vii), or both steps (vi) and (vii); (vi) transporting the final silicone polymer gum reaction product to a filling means for filling into suitable storage containers; (vii) transporting the final silicone polymer gum reaction product to a compounding means for combining the silicone polymer gum reaction product with other ingredients.

[0029] Before use, the selected organocyclosiloxane oligomer is stored in a suitable storage container or is directly supplied from production.When the selected organocyclosiloxane oligomer is directly supplied from production to a storage container for immediate use or in the storage container for immediate use, or when the selected organocyclosiloxane oligomer is directly supplied from production, the optional removal of residual water is optional and probably unnecessary, since there is little water to remove.However, when the selected organocyclosiloxane oligomer is stored in a suitable storage container for several days or more, the removal of residual water is necessary.In step (i) of the process, the selected organocyclosiloxane oligomer starting material is transported, for example, pumped from a storage container, or transported directly from production to a polymerization reactor. The polymerization reactor is a conical screw dump extruder as described in US Pat. No. 7,556,419 and US Pat. App. Pub. No. 2021113975 from Colmec SpA for compounding pre-prepared components to make a base composition or a curable silicone-based composition. The organocyclosiloxane oligomer is introduced into the conical screw dump extruder and introduced into the mixing chamber through an inlet. If one oligomer stream is being fed into the polymerization reactor, it may be transferred directly. If two or more organocyclosiloxane oligomer streams are being used, they may be premixed in a suitable mixer before entering the polymerization reactor, if desired, so that the different organocyclosiloxane oligomers are thoroughly intermixed when introduced into the polymerization reactor. When more than one organocyclosiloxane oligomer is utilized, each organocyclosiloxane oligomer may be introduced simultaneously into the conical screw dump extruder or by any other suitable mixing regime, such as having an organocyclosiloxane oligomer at the start of the process and introducing aliquots of a second organocyclosiloxane oligomer periodically during the process of producing the silanol terminated silicone polymer gum.

[0030] The organocyclosiloxane oligomers used herein have low viscosity when in liquid form, e.g., less than 100 mPa.s at 25° C. Conical screw dump extruders are not designed to mix low viscosity organocyclosiloxane oligomers as the main component, nor are they actually used as polymerization reactors. Conical screw dump extruders are designed to intermix preformed polymers and fillers into a base material or compound with other components that are not intended for polymerization using low viscosity organocyclosiloxane oligomers as the initial component.

[0031] As mentioned above, during step (i) of the process, the polymerization reactor is heated to a predetermined temperature between 40 and 170°C in an inert atmosphere. The initially elevated temperature selected is chosen with the intention of removing excess water by evaporation in step (ii) after addition of the suitable -OH species containing chain initiator / endblocker, although the excess water may additionally or alternatively be extracted by an in-line molecular sieve trap which may be installed in the piping to remove water as the ingredients are pumped therethrough. When relying on evaporation to remove excess water in step (ii), the predetermined temperature selected in step (i) is typically between 100 and 170°C. The inert atmosphere may be any suitable inert atmosphere, but is typically a nitrogen atmosphere. Introduction of a suitable -OH species to function as a chain initiator / endblocker in step (ii) of the process to the polymerization reactor can occur before, simultaneously with, or after step (i), in which the resulting organocyclosiloxane oligomer and chain initiator / endblocker combination is mixed and heated to a predetermined temperature between 100°C and 170°C, optionally with removal of residual water as described above.

[0032] Once residual water has been removed, in step (iii), if necessary, a basic catalyst suitable for catalyzing the ring-opening polymerization is introduced into the polymerization reactor, thereby initiating the ring-opening polymerization and subsequently polymerizing to produce the silicone polymer gum. The predetermined temperature selected in step (i) may be the preferred polymerization reaction temperature for step (iii) after the catalyst is introduced.

[0033] Typically, for catalyst types (I) to (VIII), the preferred polymerization reaction temperature is 100 °C or higher and 170 °C or lower. However, if the predetermined temperature in step (i) is different from the preferred polymerization reaction temperature in step (iii), the mixture obtained from step (ii) may be heated or cooled before the addition of the catalyst.

[0034] In the case of transition catalyst (IX), the required reaction temperature is 40 to 60 °C in an inert atmosphere. Therefore, if a temporary catalyst is selected for use and water is removed by heating in step (ii), after cooling the polymerization reactor to a temperature of 40 to 60 °C in an inert atmosphere for the polymerization reaction, the catalyst is introduced, and then, instead of introducing a neutralizing agent to quench the reaction in step (iv), the reaction mixture is heated to a temperature of at least 80 °C at the end of the polymerization process to generate ammonia gas, which is then removed from the polymer reactor under vacuum. This can have the advantage that the use of vacuum can be helpful in removing at least some of the residual organocyclosiloxanes and by-products of the polymerization reaction using heat and vacuum in a conical screw dump extruder polymerization reactor.

[0035] As already shown, the polymerization reactor is a conical screw dump extruder comprising a conical twin-shaft chamber housing two counter-rotating conical screws converging towards an extrusion die. During use, the starting components for the polymerization reaction and the product within the polymerization reactor are driven towards the extrusion die by the counter-rotating screws.

[0036] However, when the obturator is closed, the starting components and / or polymerization products are forced back into the conical twin-axis chamber for further recirculation / additional mixing to increase the homogeneity of the polymerization products during polymerization. The two counter-rotating screws are in converging and intersecting conical channels, with the peripheral contour of the threads extending adjacent to the channel surface. Thus, the conical contour of the screws gradually narrows the material volume, and the pressure increases as the reactants and polymerization products approach the closed extrusion die during the production process of silanol-terminated silicone polymer gums.

[0037] This pressure increase allows for recirculation of the contents of the reaction chamber. If desired, the rotation of the two screws may be temporarily reversed to aid in the polymerization and / or mixing process, for example, perhaps when the polymer reaches a very high viscosity, such as a hard gum. Polytetrafluoroethylene (PTFE) packing may be utilized. However, in one embodiment, the screw may be equipped with a lip seal on the shaft of the screw, if desired.

[0038] The extrusion die has an inlet and an outlet, and the passage through the extrusion die from the inlet to the outlet of the polymerization reactor is controlled by the aforementioned blocking means. The blocking means is maintained in a closed position blocking the outlet of any contents present in the polymerization reactor (conical screw dump extruder) during the production process of the silanol-terminated silicone polymer gum (e.g., steps (i) to (v) above), so that the contents in the reactor, such as starting components, polymer, and any by-products, are driven by a pair of counter-rotating screws toward the extrusion die and then returned to the conical reaction chamber for further mixing repeatedly over a predetermined polymerization reaction period.

[0039] In step (iv), the reaction is quenched. This is most often accomplished by introducing a suitable neutralizing agent, as described above, into the polymerization reactor to neutralize the mixture resulting from the silanol-terminated silicone polymer gum production process, particularly the silicone polymer gum resulting from step (iii). Optionally, if desired, a vacuum may be applied inside the polymerization reactor to vacuum strip the quenched product of steps (iii) and (iv), e.g., to remove any residual organocyclosiloxane oligomers and / or impurities and / or by-products.

[0040] Step (v) of the process involves cooling the resulting polymerization product to a predetermined temperature of from 30°C to 80°C, alternatively from 30°C to 70°C, and then, once cooled, moving the occlusion means to an open position to allow the resulting silicone polymer gum product to be extruded through the extrusion die.

[0041] In step (vi), the silicone polymer gum product coming out of the polymerization reactor through the extrusion die is collected and transferred to a suitable filling means, or if it has an acceptable viscosity, it may be pumped to a filling means. In step (vii), the silicone polymer gum product coming out of the polymerization reactor through the extrusion die is transported to a compounding means for further processing, i.e., for combining with additional ingredients to make a gel product, a rubber base, or a curable rubber compound, for example, by compounding with other ingredients to make a silicone rubber base, after mixing with a suitable reinforcing filler or a suitable curable silicone rubber composition, the filler, if necessary a crosslinking agent, and a catalyst or curing agent. The compounding means may be any suitable compounder type mixer, such as a sigma blade kneader mixer, a bottom discharge kneader mixer, a conical twin mixer, such as a screw dump extruder, a planetary extruder, a co-kneader extruder, a twin screw extruder, a single screw extruder, and / or a two-roll mill, but in this case, in a preferred embodiment, it may be a second conical screw dump extruder. In such cases, the silanol-terminated silicone polymer gum product may, if desired, first undergo a reaction to replace the silanol end groups with another end group, for example an unsaturated end group such as an alkenyl or alkynyl end group, typically an alkenyl end group such as a vinyl end group. Alternatively, the polymer gum may be end-capped with a trialkyl end group. If end-capping is performed, it is performed by maintaining the freshly polymerized silanol gum at a temperature of 20-70°C and then adding a small molecule such as a silane or disilazane, for example, divinyltetramethyldisilazane or hexamethyldisilazane, with continuous mixing. The silazane then reacts with the -OH end groups on the reaction product to "cap" it. The temperature may then be increased to 100°C-190°C to remove any remaining by-products such as ammonia. Optionally, a vacuum may be applied if desired or additionally required.As mentioned above, previous batch processes for making silicone polymer gums using the above ring-opening polymerization process often use a kneader-type mixer to prepare silicone polymer gums (high-viscosity silicone polymers with a viscosity of more than 1,000,000 mPa.s at 25°C), and then transfer / discharge the resulting polymer into a second device, such as a general-purpose or large hopper extruder for down packaging. One advantage of utilizing a conical screw dump extruder as the polymerization reactor described herein is that it eliminates many of the previous problems, since there is no need to transfer polymer material between devices. The use of a conical screw dump extruder allows mixing and delivery to the filling means from the same device, thereby avoiding contamination and reliability issues.

[0042] Furthermore, the use of a conical screw dump extruder as a polymerization reactor in this process avoids the need to dump and scrape off residual material between batches for reasons of changeover losses, thus avoiding the previously laborious cleaning steps between batches, avoiding the need to transfer polymer between equipment, and thus protecting operators from exposure to any potentially toxic materials, since the conical screw dump extruder is effectively self-cleaning. The conical shape of the screw, combined with the shape of the inner surface of the mixing body, allows the contents to be completely removed from the batch. [Brief description of the drawings]

[0043] The disclosure herein is further described below with reference to the drawings. [Figure 1] FIG. 1 shows a schematic diagram of an example process for producing the silanol-terminated silicone polymer gums described herein.

[0044] In FIG. 1, a conical screw dump extruder (1) is provided which is utilized as a polymerization reactor for the ring-opening polymerization of organocyclosiloxane oligomers. The conical screw dump extruder (1) has a conical biaxial chamber (1a) housing two intermeshing conical screws (not shown) which converge into an extrusion die (2). Also provided is an obturator (3) in the form of a plate which can be moved between an open position and a closed position, such that in the closed position the obturator (3) is designed to prevent the exit of the polymer product during the production process of the silanol-terminated silicone polymer gum, and in the open position (not shown) to allow said polymer product to exit through the extrusion die. The two intermeshing conical screws operate in a counter-rotating manner and are driven by a motor (14) of the conical screw dump extruder (1). The intermeshing conical screws may be equipped with a lip seal on the shaft if desired.

[0045] FIG. 1 also shows two organocyclosiloxane oligomer storage tanks (4) and (5) and respective delivery lines (6) and (7) for transferring the respective organocyclosiloxane oligomers through inlet ports (8) and (9) to the conical screw dump extruder (1). In the illustrated embodiment, two inlet ports (8) and (9) are provided for introducing the organocyclosiloxane oligomers to the conical screw dump extruder (1). If desired, these may be replaced by the use of an organocyclosiloxane oligomer hopper (not shown) replacing the inlet ports (8) and (9) for feeding the organocyclosiloxane oligomers to the conical screw dump extruder (1). Alternatively or additionally, the delivery lines may lead to a mixing means, for example a static mixer for mixing the organocyclosiloxane oligomers together before entering the conical screw dump extruder (1), if desired.

[0046] Also provided is a neutralizing agent supply tank (10), a neutralizing agent delivery line (11), and a neutralizing agent inlet port (12). Also provided is a catalyst supply tank (15), a catalyst delivery line (16), and a catalyst inlet port (17). Also provided is a chain initiator / endblocker supply tank (20), a chain initiator / endblocker delivery line (21), and a chain initiator / endblocker inlet port (22).

[0047] As the silicone polymer gum prepared in the conical screw dump extruder (1) exits through the extrusion die (2), it may be transported, in this case to a filling means (30), for filling and storage.

[0048] In use, any number of different organocyclosiloxane oligomers may be utilized, but typically one organocyclosiloxane oligomer or a mixture of two, three, four, or five different organocyclosiloxane oligomers will be utilized, and more often one, two, or three organocyclosiloxane oligomers, usually one or two. For the purposes of this illustration, there are two selected organocyclosiloxane oligomers, which are fed from organocyclosiloxane oligomer storage tanks (4) and (5) via respective delivery lines (6) and (7) and through respective inlet ports (8) and (9) to the conical screw dump extruder (1). For example, when a fluorosilicone polymer / copolymer gum is being prepared, the organocyclosiloxane oligomer fed to the conical screw dump extruder (1) is (3,3,3-trifluoropropyl)methylcyclotrisiloxane: ((CH 3 )(CH 2 CH 2 CF 3 )SiO) 3It may be alone or in combination with one or more other organocyclosiloxane oligomers, such as octamethylcyclotetrasiloxane, hexamethylcyclotrisiloxane, tri-(methylvinyl)cyclotrisiloxane, tri-(ethylvinyl)cyclotrisiloxane, tetra-(methylvinyl)cyclotetrasiloxane, or tetra-(ethylvinyl)cyclotetrasiloxane. For illustrative purposes, we shall hereinafter describe the process based on the organocyclosiloxane oligomers present being tri-(fluoropropylmethyl)tricyclosiloxane and, optionally, tri-(methylvinyl)cyclotrisiloxane. Thus, for purposes of this description, (3,3,3-trifluoropropyl)methylcyclotrisiloxane is fed to the conical screw dump extruder (1) from the organocyclosiloxane oligomer storage tank (4), and tri-(methylvinyl)cyclotrisiloxane is fed to the conical screw dump extruder (1) from the organocyclosiloxane oligomer storage tank (5) when / when desired. They may be fed in any order, simultaneously, or in fact may be premixed and fed if desired. The starting components for the polymerization are maintained in an inert atmosphere, typically a nitrogen atmosphere. Typically, the conical screw dump extruder (1) may be purged with nitrogen prior to the introduction of the organocyclosiloxane oligomer.

[0049] Simultaneously or subsequent to the introduction of the organocyclosiloxane oligomer into the conical screw dump extruder (1), an initiator / endblocking agent is fed from a feed tank (20) through a chain initiator / endblocking agent delivery line (21) into the conical screw dump extruder (1) through said chain initiator / endblocking agent inlet port (22) and then mixed with the organocyclosiloxane oligomer using the two intermeshing conical screws of the conical screw dump extruder (1). The blocking means (3) is in a closed position. The resulting mixture is heated to a predetermined temperature between 40 and 170°C, typically 100 and 170°C, to remove any excess water. The initiator / endblocking agent may be, for example, any one of the initiators / endblocking agents described above, but in this example, is of the following structure: HO-(MeTFPSi-O) d -H (wherein the average value of d is 4 to 8).

[0050] Once excess water has been removed / evaporated and the mixture in the conical screw dump extruder (1) has reached a predetermined reaction temperature of 40-170°C depending on the catalyst used in the polymerization reaction, the catalyst is introduced into the conical screw dump extruder (1) through the catalyst inlet port (17) from the catalyst supply tank (15) via the catalyst delivery line (16). The catalyst may be any suitable catalyst as described above, but in this case is preferably, for example, a suitable silanolate, e.g., an alkali metal silanolate, a non-metal silanolate such as an ammonium silanolate, or an alkali metal hydroxide. In the examples herein, a suitable alkali metal silanolate is utilized as the catalyst.

[0051] The polymerization ingredients are then mixed continuously using the two intermeshing conical screws of the conical screw dump extruder (1) with the obturator means (3) in the closed position for a predetermined period of time depending on the desired polymer product.

[0052] During the production process of silanol-terminated silicone polymer gums, the contents of the conical screw dump extruder (1), i.e., the polymerization ingredients and the gradually resulting polymer or gum, are continuously mixed using two counter-rotating intermeshing conical screws, so that during polymerization, the contents are driven by the pair of counter-rotating screws towards the extrusion die (2) and then reversed back into the conical twin-screw chamber (1a) and back into the conical screw dump extruder (1), throughout the period during which they are prevented from exiting through the extrusion die (2) by the obstruction means (3) in the closed position.

[0053] If desired, a sample of the polymer produced via the ring-opening polymerization process in the conical screw dump extruder (1) may be removed and analyzed to verify that the viscosity, or Williams plasticity in the case of gums, is within a predetermined tolerance range before the sample is discharged from the conical screw dump extruder (1) through the extrusion die (2) after the occlusion means (3) is opened.

[0054] Once the polymerization reaction is complete, i.e., by undergoing reaction for a certain predetermined length of time or reaching a certain physical property value, e.g., a certain William Plasticity value, the polymerization reaction may be quenched, for example, by introducing a suitable neutralizing agent, typically a weak Lewis acid, as described above. The neutralizing agent is transferred from a neutralizing agent supply tank (10) through a neutralizing agent delivery line (11) to the conical screw dump extruder (1) via a neutralizing agent inlet port (12). The neutralizing agent may be, for example, carbon dioxide. Any remaining starting components and / or by-products generated during the production process of the silanol terminated silicone polymer gums herein may then be extracted by vacuum and / or vacuum stripped.

[0055] After the optional vacuum extraction or vacuum stripping step is completed, the resulting polymerization product in the conical screw dump extruder (1) is cooled and then the closing means (3) is moved to an open position to allow the silicone polymer gum product to be extruded from the conical screw dump extruder (1) through the extrusion die (2) and, in this case of FIG. 1, transferred to a filling means (30) for filling / storage.

[0056] The silanol terminated silicone polymer gums prepared by the process herein have a William's plasticity according to ASTM D-926-08 of at least 200 mm / 100, alternatively, the silanol terminated silicone polymer gums prepared by the process herein have a William's plasticity according to ASTM D-926-08 of at least 225 mm / 100, alternatively, at least 250 mm / 100 according to ASTM D-926-08.

[0057] The process for producing silanol-terminated silicone polymer gums described herein, utilizing a conical screw dump extruder (1) as a polymerization reactor (rather than as a means of compounding as previously identified), offers several advantages over previous polymerization reactors used heretofore. For example, the use of a conical screw dump extruder (1) allows the resulting silicone polymer gum product to be extruded through an extrusion die (2) when the conical screw dump extruder (1) functions as both a reactor and an extruder and the closing means (3) is in an open position, where the polymer can be transported directly to a filling means (30), allowing for mixing of the resulting polymer / gum and transfer to the filling means from the same equipment. The use of this single equipment provides the further advantage that its use reduces the risk of contamination and reliability issues.

[0058] Furthermore, typically, the conical screw dump extruder (1), such as that commercially available from Colmec SpA (Busto Arsizio, Italy), has a clamshell-type opening design that allows easy cleaning during use as a polymerization reactor, if necessary. It has also been found that little or no dumping and scraping is required during the preparation of polymer batches, due to the small loss of weight of the total batch remaining in the mixer after extrusion (heel). This also has the advantage of reducing the labor intensity of the process, further limiting the risk of operator exposure to the components and by-products involved in the polymerization process described herein.

[0059] In addition, the conical screw dump extruder may have integrated vacuum system capability that can allow for stripping of the silicone polymer product to reduce the levels of residual starting materials and / or by-products. EXAMPLES

[0060] Below are a series of examples provided to demonstrate the suitability of the process for making silanol-terminated silicone polymer gums having a William plasticity of at least 200 mm / 100 according to ASTM D-926-08. All gums prepared and / or used in the following examples contain at least one silanol end group. All plasticity targets and actual measurements shown in the following tables are William plasticity values ​​according to ASTM D-926-08. The reaction times provided describe the length of time used in the examples to make the gums from the starting materials. The batch size is the approximate volume of the starting ingredients in the conical screw dump extruder used in the examples. In the tables, TFP is intended to mean trifluoropropyl.

[0061] In Example 1-1, a silanol-terminated silicone polymer gum was prepared according to the process for producing silanol-terminated silicone polymer gum using a Colmec™ CTM-65 mixer as the conical screw dump extruder (1). The organocyclosiloxane oligomer used was trifluoropropylmethylsiloxane trimer and a small amount of vinylmethylsiloxane trimer. The -OH species-containing chain initiator / endblocker had the following structure: HO(MeTFPSi-O) d -H The starting components were silanol (wherein the average value of d is 4-8) and the catalyst was a silanolate. Each component was introduced into a conical screw dump extruder as described herein. The final volume of the starting components was approximately 5 liters, and more than (>) 99.5% of the mixture was one or more organocyclosiloxane oligomers with appropriate levels of silanolate catalyst. The ring-opening polymerization step was carried out at a temperature of about 130°C for about 60 minutes, after which the reaction / catalysis was quenched using solid carbon dioxide. The blocking means (3) in the conical screw dump extruder (1) was maintained in a closed position until the neutralizing agent was added. The blocking means (3) was then opened to extrude the resulting prepared silanol-terminated silicone polymer gum through the extrusion die (2), and then transported to the filling. The resulting silanol terminated silicone polymer gum made in a conical screw dump extruder (1) having a William plasticity of greater than 200 mm / 100 was found to be well mixed and extruded cleanly through the extrusion die (2), with only about 0.1 wt. % of the total batch weight remaining in the mixer after extrusion (also referred to as the 0.1 wt. % heel).

[0062] For Example 1.2, a pre-prepared fluorosilicone polymer gum was inserted into a conical screw dump extruder (1), mixed for a short time with the occlusion means (3) closed, and then extruded through an extrusion die (2) once the occlusion means was opened to determine whether the gum was well extruded. It was found that rubbers with a William plasticity of more than 200 mm / 100 were well mixed and extruded cleanly through the extrusion die (2), with less than (<) 1.5% by weight of the total batch weight remaining in the mixer after extrusion.

[0063] In the case of Example 1-3, a process similar to that of Example 1-1 was carried out to produce a silanol-terminated silicone polymer gum with a lower Williams plasticity value. The only organocyclosiloxane oligomer used was trifluoropropylmethylsiloxane trimer. It was found that the process worked and that the silanol-terminated silicone polymer gum was thoroughly mixed and extruded cleanly through the extrusion die (2), with less than 1.5% by weight of the total batch remaining in the mixer after extrusion.

[0064] The results and details are summarized in Table 1a.

[0065] [Table 1]

[0066] The actual plasticity of the gum product could be finely tuned by controlling the chain initiator / endblocker level and / or catalyst level.

[0067] Two comparative examples were then evaluated. Comparative Example 1 was prepared and tested for extrudability and mixing in a Colmec™ CTM-65 mixer, while Comparative Example 2 was another pre-formulated gum with much lower William Plasticity results compared to Examples 1-1 through 1-3 above. This was achieved by introducing a higher loading of endblocker into the mixer.

[0068] In the case of Comparative Example 1, a gum was prepared using a Colmec™ CTM-65 mixer. In this example, a plasticity of less than 200 mm / 100 was intentionally polymerized in a manner similar to that of Example 1-1. However, in this case, the resulting gum had a much lower plasticity target and actual reading. The resulting gum was found to be unsuitable for preparation in the Colmec™ CTM-65 mixer, because it was very sticky in the conical twin-axis chamber (1a), and it was found that only 42% by weight of the silanol-terminated silicone polymer gum was extruded from the Colmec™ CTM-65 mixer, with 58% remaining in the extruder, resulting in the fact that a laborious cleaning regime was required before the next batch could be prepared. This was deemed unsatisfactory and it was therefore believed that this Williams plasticity material could not be polymerized satisfactorily in the Colmec™ CTM-65 mixer because it would not extrude satisfactorily and would therefore require a rather time consuming cleaning regime between batches.

[0069] Comparative Example 2 was a second pre-prepared resulting silanol-terminated silicone polymer gum. In this case, it was prepared from dimethylsiloxane trimer as the starting organocyclosiloxane oligomer. The pre-prepared gum was inserted into a conical screw dump extruder (1), mixed for a short time with the occlusion means (3) closed, and then extruded through the extrusion die (2) when the occlusion means (3) was opened to determine whether the gum was successfully extruded. It was found that gums with a William plasticity of less than 200 mm / 100 were well mixed, but only about 65% by weight of the gum was successfully extruded through the extrusion die (2), with 35% by weight remaining in the extruder, a fact that resulted in the need for a laborious cleaning regime before the next batch could be prepared. This was deemed unsatisfactory and it was therefore believed that this Williams plasticity material could not be polymerized satisfactorily in the Colmec™ CTM-65 mixer because it would not extrude satisfactorily and would therefore require a rather time consuming cleaning regime between batches.

[0070] The results are summarized in Table 1.b below.

[0071] [Table 2]

Claims

1. 1. A process for producing a silanol terminated silicone polymer gum having a William's plasticity of at least 200 mm / 100 according to ASTM D-926-08, comprising carrying out a ring-opening polymerization of one or more organocyclosiloxane oligomers having 3 to 5 siloxane units per molecule, said siloxane units comprising dialkylsiloxane units, alkylalkenylsiloxane units, trifluoroalkylalkylsiloxane units, perfluoroalkylalkylsiloxane units, phenylalkylalkylsiloxane units, or mixtures thereof in said organocyclosiloxane ring, each alkyl group being the same or different and containing 1 to 10 carbons, each alkenyl group being the same or different and having 2 to 10 carbons, said ring-opening polymerization being (i) transporting one or more organocyclosiloxane oligomers having 3 to 5 siloxane units per molecule to a polymerization reactor heated to a predetermined temperature of 40 to 170° C. in an inert atmosphere; (ii) simultaneously with or subsequent to step (i), introducing a suitable -OH species containing chain initiator / endblocker into the polymerization reactor and mixing with the organocyclosiloxane oligomer, optionally removing residual water; (iii) introducing a catalyst suitable for catalyzing the ring-opening polymerization into the polymerization reactor to form a reaction mixture with the resulting mixture of step (ii) and subsequently allowing the ring-opening polymerization of the at least one organocyclosiloxane oligomer to proceed to produce a silicone polymer gum reaction product; (iv) quenching the silicone polymer gum reaction product resulting from step (iii) and optionally vacuum stripping said silicone polymer gum reaction product using vacuum means within said polymerization reactor; (v) cooling the silicone polymer gum reaction product resulting from step (iv) to form a final silicone polymer gum reaction product, followed by either step (vi) or (vii), or both steps (vi) and (vii); (vi) transporting the final silicone polymer gum reaction product to a filling means (30) for filling into suitable storage containers; (vii) transporting the final silicone polymer gum reaction product to a compounding means for combining said silicone polymer gum reaction product with other ingredients; The polymerization reactor employed is a conical screw dump extruder (1) with a conical twin chamber (1a) housing two counter-rotating conical screws converging towards an extrusion die (2) having an inlet and an outlet, the passage through the extrusion die (2) being controlled by a blocking means (3) such that the outlet of the extrusion die (2) is closed by the blocking means (3) until the end of step (v) and until the end of steps (vi), (vii), or both (vi) and (vii). wherein said counter-rotating conical screws are configured to be open between said two conical twin-axis chambers (1 a) and (1 b) so that, during polymerization, said reaction mixture is driven by said pair of counter-rotating conical screws towards the extrusion die (2) and then returned to said conical twin-axis chamber (1 a) when said extrusion die (2) is closed by said obturation means (3) and then, during steps (vi), (vii), or both (vi) and (vii), extruded through said extrusion die (2) and transported to said charging means (30) and / or said compounding means, respectively.

2. 2. The process for producing a silanol terminated silicone polymer gum according to claim 1, wherein each organocyclosiloxane oligomer having from 3 to 5 siloxane units per molecule is a cyclic trimer.

3. 3. The process for producing a silanol-terminated silicone polymer gum according to claim 1 or 2, wherein the organocyclosiloxane oligomer comprises alkylvinylsiloxane units and / or trifluoropropylmethylsiloxane units.

4. The organocyclosiloxane oligomer is selected from the group consisting of octamethylcyclotetrasiloxane, hexamethylcyclotrisiloxane, decamethylcyclopentasiloxane, penta(methylvinyl)cyclopentasiloxane, tetra(phenylmethyl)cyclotetrasiloxane, penta(methylhydro)cyclopentasiloxane, tri(methylvinyl)cyclotrisiloxane, tri(ethylvinyl)cyclotrisiloxane, tetra(methylvinyl)cyclotetrasiloxane, tetra(ethylvinyl)cyclotetrasiloxane, penta(methylvinyl)cyclopentasiloxane, penta(ethylvinyl)cyclopentasiloxane, tri(fluoropropylmethyl)tricyclosiloxane, tri(fluoropropylethyl)tricyclosiloxane, 4. A process for producing the silanol terminated silicone polymer gum of any one of claims 1 to 3, comprising tetra-(fluoropropylmethyl)tetracyclosiloxane, tetra-(fluoropropylethyl)tetracyclosiloxane, penta-(fluoropropylmethyl)pentacyclosiloxane, penta-(fluoropropylethyl)pentacyclosiloxane, tri-(fluoroethylmethyl)tricyclosiloxane, tri-(fluoroethylethyl)tricyclosiloxane, tetra-(fluoroethylmethyl)tetracyclosiloxane, tetra-(fluoroethylethyl)tetracyclosiloxane, penta-(fluoroethylmethyl)pentacyclosiloxane, penta-(fluoroethylethyl)pentacyclosiloxane, and mixtures thereof.

5. The process for producing a silanol terminated silicone polymer gum according to any one of claims 1 to 4, wherein the catalyst is a silanolate catalyst.

6. The process for producing a silanol-terminated silicone polymer gum according to any one of claims 1 to 5, wherein the catalyst is an alkali metal-containing silanolate catalyst.

7. The process for producing a silanol terminated silicone polymer gum according to any of claims 1 to 6, wherein the quenching in step (iv) is carried out by introducing a neutralizing agent.

8. The neutralizing agent is phosphoric acid, tris(chloroethyl)phosphite silyl phosphate, carbon dioxide, NaH ２ P.O. ４ , Na ２ H.P.O. ４ 8. A process for producing the silanol terminated silicone polymer gum of claim 7, comprising:

9. The process for producing a silanol terminated silicone polymer gum according to any one of claims 1 to 6, wherein the catalyst is a temporary silanolate catalyst.

10. The production process of the silanol-terminated silicone polymer gum according to any one of claims 1 to 9, wherein in step (i), the selected organocyclosiloxane oligomer is transported from a suitable storage tank (4, 5) or directly supplied from production.

11. The production process of the silanol-terminated silicone polymer gum according to any one of claims 1 to 10, wherein the compounding means in step (vii) is a second conical screw dump extruder.

12. A silanol-terminated silicone polymer gum having a William plasticity of at least 200 mm / 100 according to ASTM D-926-08, obtainable or obtainable by the process according to any one of claims 1 to 11.

13. The silanol-terminated silicone polymer gum according to claim 12, having a William plasticity of at least 225 mm / 100 according to ASTM D-926-08.

14. The silanol-terminated silicone polymer gum according to claim 12 or 13, which is linear or substantially linear and has less than 2.5% by weight of branches.

15. Use of a conical screw dump extruder (1) as a polymerization reactor in the production process of a silanol-terminated silicone polymer gum, wherein the silanol-terminated silicone polymer gum has a William plasticity of at least 200 mm / 100 according to ASTM D-926-08 and includes ring-opening polymerization of one or more organocyclosiloxane oligomers having 3 to 5 siloxane units per molecule, and the siloxane units include dialkylsiloxane units, alkylalkenylsiloxane units, trifluoroalkylalkylsiloxane units, perfluoroalkylalkylsiloxane units, and phenylalkylalkylsiloxane units, or mixtures thereof in the organocyclosiloxane ring, each alkyl group is the same or different and contains 1 to 10 carbons, each alkenyl group is the same or different and has 2 to 10 carbons, and the ring-opening polymerization includes (i) transporting one or more organocyclosiloxane oligomers having 3 to 5 siloxane units per molecule to a polymerization reactor heated to a predetermined temperature of 40 to 170 °C in an inert atmosphere; (ii) simultaneously with or subsequent to step (i), introducing a suitable -OH species containing chain initiator / endblocker into the polymerization reactor and mixing with the organocyclosiloxane oligomer, optionally removing residual water; (iii) introducing a catalyst suitable for catalyzing the ring-opening polymerization into the polymerization reactor to form a reaction mixture with the resulting mixture of step (ii) and subsequently allowing the ring-opening polymerization of the one or more organocyclosiloxane oligomers to proceed to produce a silicone polymer gum reaction product; (iv) quenching the silicone polymer gum reaction product resulting from step (iii) and optionally vacuum stripping the silicone polymer gum reaction product using vacuum means within the polymerization reactor; (v) cooling the silicone polymer gum reaction product resulting from step (iv) to form a final silicone polymer gum reaction product, followed by either step (vi) or (vii), or both steps (vi) and (vii); (vi) transporting the final silicone polymer gum reaction product to a filling means (30) for filling into suitable storage containers; (vii) transporting the final silicone polymer gum reaction product to a compounding means for combining said silicone polymer gum reaction product with other ingredients; The polymerization reactor employed is a conical screw dump extruder (1) with a conical twin chamber (1a) housing two counter-rotating conical screws converging towards an extrusion die (2) having an inlet and an outlet, the passage through which is controlled by a blocking means (3) such that the outlet of the extrusion die (2) is closed by the blocking means (3) until the end of step (v), and until the end of steps (vi), (vii), or both (vi) and (vii) and (v) being open during steps (vi), (vii), (vii) and (vii) so that, during polymerization, the reaction mixture is driven by the pair of counter-rotating conical screws towards the extrusion die (2), then returned to the conical twin-axis chamber (1 a) when the extrusion die (2) is closed by the closure means (3), and then extruded through the extrusion die (2) during steps (vi), (vii), or both (vi) and (vii) and transported to the filling means (30) and / or the compounding means, respectively.

Images