Silicone Manufacturing

Abstract

The present invention relates to an improved process for preparing non-catalyzed (fluoro)silicone rubber substrates prepared by incorporating reinforcing fillers into high-viscosity (i.e., greater than 1 million mPa s at 25° C.) silicone polymers and / or high-viscosity (i.e., greater than 1 million mPa s at 25° C.) fluorosilicone polymers (often referred to in the industry as silicone polymer rubbers and fluorosilicone polymer rubbers, respectively) and their copolymers, optionally in the presence of a filler treating agent utilized in situ to render the filler hydrophobic. The non-catalyzed silicone rubber substrate is then further mixed with one or more catalysts / vulcanizing agents, and optionally a crosslinking agent, and optionally various additives to form a curable one- or multi-part silicone rubber compound composition. The present invention also relates to silicone elastomers made by curing the curable one- or multi-part silicone rubber compound compositions.

Description

[Technical Field]

[0001] The present invention relates to an improved process for preparing non-catalyzed (fluoro)silicone rubber substrates prepared by incorporating reinforcing fillers into high-viscosity (i.e., greater than 1 million mPa·s at 25° C.) silicone polymers and / or high-viscosity (i.e., greater than 1 million mPa·s at 25° C.) fluorosilicone polymers (often referred to in the industry as silicone polymer gums and fluorosilicone polymer gums, respectively) and their copolymers, optionally in the presence of a filler treating agent utilized in situ to render the filler hydrophobic. The non-catalyzed silicone rubber substrate is then further mixed with one or more catalysts / vulcanizing agents, and optionally a crosslinking agent, and optionally various additives to form a curable one- or multi-part silicone rubber compound composition. The present invention also relates to silicone elastomers made by curing the curable one- or multi-part silicone rubber compound compositions.

[0002] High-viscosity silicone polymers and high-viscosity fluorosilicone polymers and their copolymers can typically be prepared by polymerization of organocyclosiloxane oligomers containing dimethylsiloxane units, methylvinylsiloxane units, trifluoroalkylmethylsiloxane units, such as trifluoropropylmethylsiloxane units and / or phenylmethylsiloxane units in the ring. The organocyclosiloxane oligomers typically have an average of 3 to 5 siloxane units in the organocyclosiloxane ring, and examples include octamethylcyclotetrasiloxane, hexamethylcyclotrisiloxane, decamethylcyclopentasiloxane, cyclopenta(methylvinyl)siloxane, cyclotri(methylvinyl)siloxane, cyclotetra(methylvinyl)siloxane, cyclotetra(phenylmethyl)siloxane, cyclopentamethylhydrosiloxane, trifluoropropylethylcyclotrisiloxane, and mixtures thereof.

[0003] Typically, organocyclosiloxane oligomers and mixtures thereof, either alone or together with a suitably end-blocked polydiorganosiloxane, undergo a polymerization process involving 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 resulting equilibrium 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 solvents. Typically, end-blocking agents are used to add functionality and control the molecular weight of the resulting polymer.

[0004] For example, silicone polymers and copolymers containing fluoroalkyl groups, such as trifluoropropyl or perfluoroalkyl groups, include, for example: R 1 (R 2 )2SiO-((R 4 )(R 3 )SiO) m -Si(R 1 )(R 2 ) (I) R 1 (R 2 )2SiO-((R 4 )(R 3 )SiO) m -((R 2 )2SiO) q Si(R 1 )(R 2 )2(II) It may be either During the ceremony, 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 4is R 2 or an unsaturated monovalent hydrocarbon group, such as an alkenyl or alkynyl group, and q and m are positive integers. The copolymer may be a random copolymer or a block copolymer.

[0005] The resulting silicone polymer gums and fluorosilicone polymer gums and copolymers thereof (hereinafter collectively referred to as (fluoro)silicone gum(s)) are utilized in the preparation of non-catalyzed base stocks of the (fluoro)silicone gum(s) (hereinafter collectively referred to as (fluorosilicone base stock(s)) which are subsequently modified with catalysts and optional additives in the preparation of catalyzed curable one- or multi-part silicone rubber compound compositions (hereinafter referred to as "(fluoro)silicone rubber compound compositions"), often referred to as "high consistency" silicone rubber (HCR) or fluorosilicone rubber (FSR) compound compositions, which upon cure / vulcanization provide elastomers with excellent mechanical and electrical insulating properties.

[0006] The (fluoro)silicone rubber substrate is generally prepared in a first manufacturing step, sometimes called the "hot mix" step, during which the reinforcing filler is introduced into the (fluoro)silicone gum. Unless the reinforcing filler has been pretreated, a filler treating agent is also utilized in situ to render the outer surface of the filler hydrophobic. One or more optional "non-curing" additives, such as extending fillers (sometimes called non-reinforcing fillers) or alkenyl processing aids, may be incorporated in this first step, provided they do not contain catalysts / vulcanizing agents. This results in the preparation of a non-catalyzed (fluoro)silicone rubber substrate that can be stored and packaged for sale or future use, or used in the second step, sometimes called the cold mix or compounding step.

[0007] The second stage, sometimes called the cold mix stage, involves introducing at least one of the following ingredients into the non-catalyzed (fluoro)silicone rubber substrate(s) obtained from the first stage: a catalyst / vulcanizing agent and a crosslinking agent (if necessary for the vulcanizing agent), as well as other additives such as cure inhibitors, additional fillers, pigments, property modifiers, etc. The compounding ingredients and additives introduced during the second stage are thoroughly mixed into the substrate to ensure uniform distribution throughout the resulting (fluoro)silicone rubber compound composition(s). If necessary, if the compound composition is to be hydrosilylated (addition) cured, the non-catalyzed (fluoro)silicone rubber substrate may be divided so that different additives are introduced into different parts, typically into two parts, for example, part A and part B (part A contains the catalyst, and part B contains the crosslinking agent). The two parts are mixed together before curing.

[0008] The hot mixing utilized in the manufacture of the (fluoro)silicone rubber substrate can include, for example, the metered addition of filler to the (fluoro)silicone gum to ensure that the filler is sufficiently well dispersed in the (fluoro)silicone gum and suitably hydrophobized. It also involves the removal of volatile materials, and upon completion of the mixing, it must be cooled to allow safe transportation and packaging, if necessary.

[0009] Therefore, this is a time-intensive, energy-intensive, and expensive process, much more so for the hot mixing stage than for the compounding or cold stage utilized to introduce catalysts and other curing agents, as well as other additional additives, to create the compound composition. For example, one problem is that, given the nature of (fluoro)silicone gums and the historical mixer technology available to manufacturers, such as sigma blade mixers, the production of uncatalyzed (fluoro)silicone rubber substrate(s) was only possible when reinforcing fillers were present in an amount of up to about 35% by weight of the substrate(s).

[0010] Consequently, there is a long-standing desire in the industry to improve the efficiency of the hot mixing utilized in the production of (fluoro)silicone rubber substrates and to reduce the required time required for hot mixing per kg of finished compound composition, as this could potentially provide significant economic benefits by increasing productivity in what is one of the most expensive and technically complex substrate manufacturing processes.

[0011] The present invention provides a process for the preparation of non-catalyzed (fluoro)silicone rubber substrates prepared by incorporating a reinforcing filler and optionally a hydrophobizing treatment into one or more silicone polymers, fluorosilicone polymers or copolymers thereof, in each case the one or more silicone polymers, fluorosilicone polymers or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, the process comprising the following steps: (i) introducing, as a first starting compounding component, one or more silicone polymers, fluorosilicone polymers or copolymers thereof, in each case having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, into the mixing chamber of a mixer at about 25°C, optionally in an inert atmosphere, and mixing; (ii) gradually introducing one or more reinforcing fillers, as a second starting formulation component, and optionally a third starting formulation component, one or more hydrophobizing filler treating agents, into the mixing chamber of the mixer, while continuing mixing until the mixer is charged with a predetermined amount of reinforcing fillers, which is at least 38% by weight of the total base starting formulation components, to form a base mixture; (iii) optionally, maintaining the temperature of the substrate mixture in the mixing chamber within a predetermined range of 100-200°C for a period of up to 6 hours to remove volatile materials from the substrate mixture of step (ii) to form the substrate mixture of step (iii), which step (iii) may be performed under vacuum, if utilized; (iv) cooling the obtained base mixture of step (ii) or the base mixture of step (iii) to a temperature of 25°C to 120°C before, during, or after step (iv); (v) reducing the weight percent of reinforcing filler in the base mixture of step (ii) or the base mixture of step (iii) to a predetermined amount by blending the base mixture of step (ii) or the base mixture of step (iii) with one or more additional silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 to form a non-catalyzed (fluoro)silicone rubber substrate; The mixer utilized for at least steps (i), (ii), and (iii) is a conical screw dump extruder equipped with a conical twin-screw mixing chamber containing two counter-rotating conical screws converging toward an extrusion die having an inlet and an outlet, the flow path through the extrusion die being controlled by an obstruction means, whereby the outlet of the extrusion die is such that the product of steps (iii), (iv), or (v) is not discharged if or when the uncatalyzed (fluoro)silicone rubber substrate is further processed or stored outside the conical screw dump extruder. and adapted to be closed by a closing means until extruded from the conical screw dump extruder, and adapted to be opened after steps (iii), (iv) or (v), wherein during mixing the substrate mixture is driven towards the extrusion die by a pair of counter-rotating conical screws, which are then closed by the closing means and then forced back when opened after steps (iii), (iv) or (v), allowing the product of steps (iii), (iv) or (v) to be extruded through the extrusion die for further processing and / or storage.

[0012] Also provided is a non-catalyzed (fluoro)silicone rubber substrate that is a product of the above process.

[0013] Also provided is a non-catalyzed (fluoro)silicone rubber substrate obtained or obtainable by the above process.

[0014] Also provided is the use of a conical screw dump extruder comprising a conical twin-screw mixing chamber housing two counter-rotating conical screws converging towards an extrusion die having an inlet and an outlet, in a process for the preparation of a non-catalyzed (fluoro)silicone rubber substrate prepared by introducing a reinforcing filler and optionally a hydrophobizing treatment agent into one or more silicone polymers, fluorosilicone polymers or copolymers thereof, the flow path through the extrusion die being controlled by an obstruction means whereby the outlet of the extrusion die is adapted to be closed by the obstruction means, and in each case the one or more silicone polymers, fluorosilicone polymers or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, the process comprising the steps of: (i) introducing, as a first starting compounding component, one or more silicone polymers, fluorosilicone polymers or copolymers thereof, in each case having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, into the mixing chamber of a mixer at about 25°C, optionally in an inert atmosphere, and mixing; (ii) gradually introducing one or more reinforcing fillers, as a second starting formulation component, and optionally a third starting formulation component, one or more hydrophobizing filler treating agents, into the mixing chamber of the mixer, while continuing mixing until the mixer is charged with a predetermined amount of reinforcing fillers, which is at least 38% by weight of the total base starting formulation components, to form a base mixture; (iii) optionally, maintaining the temperature of the substrate mixture in the mixing chamber within a predetermined range of 100-200°C for a period of up to 6 hours to remove volatile materials from the substrate mixture of step (ii) to form the substrate mixture of step (iii), which step (iii) may be performed under vacuum, if utilized; (iv) cooling the obtained base mixture of step (ii) or the base mixture of step (iii) to a temperature of 25°C to 120°C before, during, or after step (iv); (v) reducing the weight percent of reinforcing filler in the base mixture of step (ii) or the base mixture of step (iii) to a predetermined amount by blending the base mixture of step (ii) or the base mixture of step (iii) with one or more additional silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 to form a non-catalyzed (fluoro)silicone rubber substrate; During mixing, the substrate mixture is driven towards an extrusion die by a pair of counter-rotating conical screws, which are then closed by a closure means and then forced back when opened after step (iii), (iv) or (v), allowing the product of step (iii), (iv) or (v) to be extruded through the extrusion die for further processing and / or storage.

[0015] The present invention provides a process for the preparation of a catalyzed (fluoro)silicone rubber compound composition prepared by incorporating a reinforcing filler and optionally a hydrophobizing treatment agent into one or more silicone polymers, fluorosilicone polymers or copolymers thereof, in each case the one or more silicone polymers, fluorosilicone polymers or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, the process comprising the following steps: (i) introducing, as a first starting compounding component, one or more silicone polymers, fluorosilicone polymers or copolymers thereof, in each case having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, into the mixing chamber of a mixer at about 25°C, optionally in an inert atmosphere, and mixing; (ii) gradually introducing one or more reinforcing fillers, as a second starting formulation component, and optionally a third starting formulation component, one or more hydrophobizing filler treating agents, into the mixing chamber of the mixer, while continuing mixing until the mixer is charged with a predetermined amount of reinforcing fillers, which is at least 38% by weight of the total base starting formulation components, to form a base mixture; (iii) optionally, maintaining the temperature of the substrate mixture in the mixing chamber within a predetermined range of 100-200°C for a period of up to 6 hours to remove volatile materials from the substrate mixture of step (ii) to form the substrate mixture of step (iii), which step (iii) may be performed under vacuum, if utilized; (iv) cooling the obtained base mixture of step (ii) or the base mixture of step (iii) to a temperature of 25°C to 120°C before, during, or after step (iv); (v) reducing the weight percent of reinforcing filler in the base mixture of step (ii) or the base mixture of step (iii) to a predetermined amount by blending the base mixture of step (ii) or the base mixture of step (iii) with one or more additional silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 to form a non-catalyzed (fluoro)silicone rubber substrate; (vi) introducing, at a temperature between 25°C and 60°C, at least one catalyst or vulcanizing agent, and optionally one or more additives selected from crosslinking agents, cure inhibitors, additional fillers, pigments, property modifiers, etc.; The mixer utilized for at least steps (i), (ii), and (iii) is a conical screw dump extruder comprising a conical twin-screw mixing chamber containing two counter-rotating conical screws converging toward an extrusion die having an inlet and an outlet, the flow path through the extrusion die being controlled by an obstruction means whereby the outlet of the extrusion die is such that the product of steps (iii), (iv), or (v) is extruded from the conical screw dump extruder when or when the uncatalyzed (fluoro)silicone rubber substrate is further processed or stored outside the conical screw dump extruder. and adapted to be closed by a closing means until the base mixture is mixed with the extrusion die and adapted to be opened after step (iii), (iv) or (v), wherein during mixing, the base mixture is driven towards the extrusion die by a pair of counter-rotating conical screws, and then the extrusion die is closed by the closing means and then forced back when opened after step (iii), (iv) or (v), allowing the product of step (iii), (iv) or (v) to be extruded through the extrusion die for further processing and / or storage, and wherein step (vi) is performed simultaneously with step (v) or after step (v).

[0016] Also provided is a catalyzed (fluoro)silicone rubber compound composition that is the product of the above process.

[0017] There is also provided a catalyzed (fluoro)silicone rubber compound composition obtained or obtainable by the above process.

[0018] Also provided is the use of a conical screw dump extruder comprising a conical twin-screw mixing chamber housing two counter-rotating conical screws converging towards an extrusion die having an inlet and an outlet, in a process for the preparation of a non-catalyzed (fluoro)silicone rubber substrate prepared by introducing a reinforcing filler and optionally a hydrophobizing treatment agent into one or more silicone polymers, fluorosilicone polymers or copolymers thereof, wherein the flow path through the extrusion die is controlled by an obstruction means, whereby the outlet of the extrusion die is adapted to be closed by the obstruction means, and in each case the one or more silicone polymers, fluorosilicone polymers or copolymers thereof have a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, the process comprising the steps of: (i) introducing, as a first starting compounding component, one or more silicone polymers, fluorosilicone polymers or copolymers thereof, in each case having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, into the mixing chamber of a mixer at about 25°C, optionally in an inert atmosphere, and mixing; (ii) gradually introducing one or more reinforcing fillers, as a second starting formulation component, and optionally a third starting formulation component, one or more hydrophobizing filler treating agents, into the mixing chamber of the mixer, while continuing mixing until the mixer is charged with a predetermined amount of reinforcing fillers, which is at least 38% by weight of the total base starting formulation components, to form a base mixture; (iii) optionally, maintaining the temperature of the substrate mixture in the mixing chamber within a predetermined range of 100-200°C for a period of up to 6 hours to remove volatile materials from the substrate mixture of step (ii) to form the substrate mixture of step (iii), which step (iii) may be performed under vacuum, if utilized; (iv) cooling the obtained base mixture of step (ii) or the base mixture of step (iii) to a temperature of 25°C to 120°C before, during, or after step (iv); (v) reducing the weight percent of reinforcing filler in the base mixture of step (ii) or the base mixture of step (iii) to a predetermined amount by blending the base mixture of step (ii) or the base mixture of step (iii) with one or more additional silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 to form a non-catalyzed (fluoro)silicone rubber substrate; (vi) introducing, at a temperature between 25°C and 60°C, at least one catalyst or vulcanizing agent, and optionally one or more additives selected from crosslinking agents, cure inhibitors, additional fillers, pigments, property modifiers, etc.; During mixing, the substrate mixture is driven towards an extrusion die by a pair of counter-rotating conical screws, which is then closed by a closure means and then forced back when opened after step (iii), (iv) or (v), allowing the product of step (iii), (iv) or (v) to be extruded through the extrusion die for further processing and / or storage, and step (vi) is performed simultaneously with step (v) or after step (v).

[0019] It will be understood that this disclosure relates to a process for making a non-catalyzed (fluoro)silicone rubber substrate, which process can be used to make a curable compound composition by adding catalysts, crosslinkers, etc. to the substrate. This invention does not relate to the polymerization process for making silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, which are one of the starting compounding ingredients in the process described herein.

[0020] Non-catalyzed (fluoro)silicone rubber substrate is intended to mean a mixture of a (fluoro)silicone polymer having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 and a reinforcing filler that does not contain a curing agent and / or a crosslinking agent, i.e. does not contain a catalyst; therefore, such a mixture cannot be cured into an elastomer or the like until it is converted into a curable compound composition containing a curing agent and / or a crosslinking agent (if required) and other additives.

[0021] Reinforcing fillers are incorporated into silicone rubber materials to enhance the strength and toughness of the cured elastomer material. Reinforcing fillers are highly surface active and have a high surface area, which reinforces the cured siloxane polymer matrix through hydrogen bonding and other means. Extending fillers (sometimes called non-reinforcing fillers) generally have a low surface area and are provided primarily to reduce the cost of silicone rubber. Reinforcing fillers typically achieve at least one of the following mechanical properties: they can improve excellent tensile strength, tear strength, and flex fatigue resistance, increase or reduce crepe hardening, improve compression set resistance, and provide silicone elastomers with excellent resistance to heat aging, for example.

[0022] Surprisingly, it has been discovered that by utilizing a conical screw dump extruder instead of a typical traditional mixer, such as a sigma blade mixer, the amount of reinforcing filler that can be introduced into a non-catalyzed (fluoro)silicone rubber substrate before reaching saturation (at which point the substrate disintegrates and is no longer continuous) can be increased by several weight percent. This increase is significant in that it increases the efficiency of substrate production, i.e., the productivity of substrate production, by reducing the thermal mixing time per kg of finished substrate, resulting in economic benefits and increased productivity of the thermal mixer. This productivity increase is achieved through the ability to produce more highly filled non-catalyzed (fluoro)silicone rubber substrate products than can be produced using current mixing technology, for example, a sigma blade mixer, where the absolute maximum filler level is believed to be no more than 35% by weight of the substrate. This increased filler loading also results in a more highly plastic material, allowing for higher shear rates during mixing. This higher shear is believed to improve filler dispersion, which appears to reduce the Williams plasticity of the resulting substrate material and may increase the clarity of cured products incorporating such substrate materials.

[0023] Furthermore, the filler content of the substrate produced using the conical screw dump extruder is typically reduced or eliminated to a predetermined level for a less-filled substrate by using additional silicone polymers, fluorosilicone polymers, or copolymers thereof. These may be silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, but may alternatively include shorter-chain silicone polymers, fluorosilicone polymers, or copolymers thereof, if desired. Such reduced or eliminated substrates have a lower Williams plasticity and are therefore easier to compound; indeed, elastomeric materials made from compound compositions produced using such substrates have been found to exhibit improved mechanical properties compared to elastomeric materials made using standard mixers, such as sigma blade mixers.

[0024] The non-catalyzed (fluoro)silicone rubber substrate prepared by the process of the present invention comprises two essential starting compounding ingredients: (a) silicone polymers, fluorosilicone polymers or copolymers thereof, in each case having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, i.e. (fluoro)silicone gums; (b) Reinforcing fillers.

[0025] If the reinforcing filler is pretreated, no other compounding ingredients are required, and the substrate is prepared by mixing the two together with any optional non-curing additives desired. Economically, the use of such pretreated fillers can significantly increase the cost of making non-catalyzed (fluoro)silicone rubber substrates, and therefore is not preferred in the majority of situations, particularly for economic reasons.

[0026] Thus, the reinforcing filler is usually introduced into the mixer in untreated form, and its outer surface is rendered hydrophobic by an in-situ treatment process during substrate preparation, in which case a third compounding component is required to produce a non-catalyzed (fluoro)silicone rubber substrate, namely, a suitable treating agent (c) to render the filler hydrophobic.

[0027] Starting compounding ingredients / component (a) The starting compounding component / component (a) is an organopolysiloxane polymer having a Williams plasticity of at least 100 mm / 100 as measured according to ASTM D-926-08. Because it is difficult to measure the viscosity of such highly viscous fluids, (fluoro)silicone gums tend to be defined by their Williams plasticity (the ability of a sample to undergo compressive deformation under an external force and retain the deformation after the force is removed) as opposed to viscosity. Typically, silicone polymer gums can have Williams plasticity values ​​of up to about 400 mm / 100 for fluorosilicone polymer gums as measured according to ASTM D-926-08.

[0028] Each organopolysiloxane of component (a) contains a plurality of siloxy units of formula (I): R' a SiO (4-a) / 2 (I)

[0029] The subscript "a" is 0, 1, 2, or 3.

[0030] Siloxy units may be described by shorthand nomenclature, i.e., "M," "D," "T," and "Q," where each R' is any suitable group, typically an organic group, such as an alkyl group. M units are siloxy units where a=3, i.e., R'SiO 1 / 2 and the D units are siloxy units where a=2, i.e., R'2SiO 2 / 2 and the T unit is a siloxy unit where a=1, i.e., R'1SiO 3 / 2 and the Q units are siloxy units where a=0, i.e., SiO 4 / 2is equivalent to

[0031] The organopolysiloxane polymer of component (a) is generally linear or substantially linear, meaning that it contains less than 2.5% by weight branches, alternatively less than 1.5% by weight branches, alternatively less than 0.5% by weight branches, alternatively less than 0.1% by weight branches due to the presence of T units (as described above) within the molecule; therefore, the average value of a in structure (I) is about 2.

[0032] Each organic group R' in the above formula (I) is independently selected from an aliphatic hydrocarbyl group, a substituted aliphatic hydrocarbyl group, an aromatic group, or a substituted aromatic group. Each aliphatic hydrocarbyl group may be exemplified by, but not limited to, an alkyl group having 1 to 20 carbons per group, alternatively 1 to 15 carbons per group, alternatively 1 to 12 carbons per group, alternatively 1 to 10 carbons per group, or alternatively 1 to 6 carbons per group, or a cycloalkyl group such as cyclohexyl. Specific examples of alkyl groups include methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl groups, alternatively methyl and ethyl groups. The substituted aliphatic hydrocarbyl group is preferably a non-halogenated substituted alkyl group.

[0033] Aliphatic non-halogenated organyl groups include, but are not limited to, the above alkyl groups having substituents such as polyoxyalkylene groups, carbonyl groups, alkoxy groups, and oxygen-containing groups such as hydroxyl groups. Examples of aromatic groups or substituted aromatic groups are phenyl groups and substituted phenyl groups having the above substituents.

[0034] Component (a) may alternatively be or include a D unit of structure (I), where one R' is an aliphatic or aromatic group and the other R' is a fluoroalkyl group, such as trifluoropropyltrifluoroethyl, and nonafluorohexyl, or a perfluoroalkyl group, such as CF3-, C2F5-, C3F7-, e.g., CF3CF2CF2- or (CF3)2CF-, C4F9-, e.g., CF3CF2CF2CF2-, (CF3)2CFCF2-, (CF3)3C- and CF3CF2(CF3)CF-, C5F 11 , e.g., CF3CF2CF2CF2CF2-, C6F 13 -, e.g., CF3(CF2)4CF2-, C7F 14 -, for example, CF3(CF2CF2)3-, as well as C8F 17 -It is.

[0035] Since peroxide curing proceeds via a radical reaction pathway, when the substrate is prepared as an intermediate for the production of a compound composition containing a peroxide catalyst, such a (fluoro)silicone gum generally contains two or more alkenyl or alkynyl groups, but reactive groups are not required, and therefore the (fluoro)silicone gum may be free of reactive groups, e.g., free of alkenyl or alkynyl groups, or may even have hydroxyl end groups.

[0036] However, if it is intended to prepare a compound composition that is hydrosilylatable or addition curable, for example, using a platinum catalyst and, for example, a crosslinker containing multiple Si-H bonds, the (fluoro)silicone gum must have at least two unsaturated groups per molecule, typically alkenyl or alkynyl groups. If present, the unsaturated groups of component (a) can be located either at the terminal or pendant positions of the organopolysiloxane polymer, or at both positions.

[0037] When present, the unsaturated groups in component (a) can be alkenyl or alkynyl groups, as described above. Each alkenyl group, when present, can contain, for example, 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, or alternatively 2 to 6 carbon atoms. When present, alkenyl groups can be exemplified by, but not limited to, vinyl, allyl, methallyl, isopropenyl, propenyl, hexenyl, and cyclohexenyl groups. When present, each alkynyl group can have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, or alternatively 2 to 6 carbon atoms. Examples of alkynyl groups can be exemplified by, but not limited to, ethynyl, propynyl, and butynyl groups. Preferred examples of the unsaturated group of component (a) include vinyl, propenyl, isopropenyl, butenyl, allyl, and 5-hexenyl.

[0038] Thus, the (fluoro)silicone gum may be, for example, trialkyl-terminated, alkenyldialkyl-terminated, alkynyldialkyl-terminated, dialkylsilanol-terminated, or terminated with any other suitable combination of end groups, provided that each polymer has a Williams plasticity of at least 100 mm / 100 as measured according to ASTM D-926-08.

[0039] Thus, component (a) may be, for example, the following: Dialkylalkenyl-terminated polydimethylsiloxanes, for example, dimethylvinyl-terminated polydimethylsiloxanes, dialkylalkenyl-terminated dimethylmethylphenylsiloxanes, for example, dimethylvinyl-terminated dimethylmethylphenylsiloxanes, trialkyl-terminated dimethylmethylvinylpolysiloxanes, dialkylvinyl-terminated dimethylmethylvinylpolysiloxane copolymers, dialkylvinyl-terminated methylphenylpolysiloxanes, dialkylalkenyl-terminated methylvinylmethylphenylsiloxanes, dialkylalkenyl-terminated methylvinyldiphenylsiloxanes, dialkylalkenyl-terminated methylvinylmethylphenyldimethylsiloxanes, trimethyl-terminated methylvinylmethylphenylsiloxanes, trimethyl-terminated methylvinyl The hydroxyl group may be methylvinylmethylphenyldimethylsiloxane, or trimethyl-terminated methylvinylmethylphenyldimethylsiloxane or a fluorosilicone polymer gum, for example, trimethyl-terminated polymethyltrifluoropropylsiloxane, dimethylalkenyl-terminated polymethyltrifluoropropylsiloxane, for example, dimethylvinyl-terminated polymethyltrifluoropropylsiloxane, dimethylsilanol-terminated polymethyltrifluoropropylsiloxane, trimethyl-terminated polymethylperfluoropropylsiloxane, dimethylalkenyl-terminated polymethylperfluoropropylsiloxane, for example, dimethylvinyl-terminated polymethyltrifluoropropylsiloxane or dimethylsilanol-terminated polymethyltrifluoropropylsiloxane.

[0040] In each case, component (a) has a Williams plasticity of at least 100 mm / 100 as measured according to ASTM D-926-08, alternatively at least 125 mm / 100 as measured according to ASTM D-926-08, alternatively at least 140 mm / 100 as measured according to ASTM D-926-08. Typically, the (fluoro)silicone gum has a Williams plasticity of about 100 mm / 100 to 400 mm / 100 as measured according to ASTM D-926-08.

[0041] Starting compounding ingredients / component (b) Component (b) is at least one reinforcing silica filler. Preferably, the reinforcing silica filler is in finely divided form. Reinforcing silica filler (b) can be exemplified by fumed silica, colloidal silica, and / or precipitated silica.

[0042] Precipitated silica, fumed silica and / or colloidal silica are typically at least 50 ml 2 / g (BET method according to ISO 9277:2010), alternatively 50-450m 2 / g (BET method according to ISO 9277:2010), alternatively between 50 and 300 m 2 / g (BET method according to ISO 9277:2010). All of these types of silica are commercially available. The reinforcing silica fillers of component (b) are hydrophilic in nature and are treated with one or more treating agents (starting compounding components / component (c)) to render them hydrophobic. Such surface-modified reinforcing fillers are finely divided, so they do not agglomerate, and the surface treatment allows the fillers to be readily wetted by rubber (a), so they can be uniformly incorporated into component (a) to produce the non-catalyzed (fluoro)silicone rubber substrates described herein.

[0043] As indicated above, the reinforcing filler is introduced into the rubber as described above to produce a non-catalyzed (fluoro)silicone rubber substrate containing at least 38 wt. % reinforcing filler based on the weight of all base starting compounding ingredients, typically 39-55 wt. %, alternatively 39-50 wt. %, alternatively 39-45 wt. %, based on the weight of all base starting compounding ingredients.

[0044] Starting compounding ingredients / component (c) Given that the silica reinforcing filler (b) is inherently hydrophilic, if it has not been pretreated to render its surface suitably hydrophobic, it is typically treated in situ during the process with a hydrophobic treatment agent. Any suitable treatment agent capable of rendering the silica surface hydrophobic can be utilized. For example, the treatment agent for the starting compounding component / component (c) can be selected from suitable organosilanes, polydiorganosiloxanes, or organosilazanes, such as hexaalkyldisilazanes, short-chain siloxanediols, and / or short-chain fluorosiloxanediols, to render the silica reinforcing filler(s) (b) hydrophobic, thereby facilitating handling and obtaining a homogeneous mixture with other compounding components.

[0045] Specific examples of component (c) include silanol-terminated trifluoropropylmethylsiloxane, silanol-terminated vinylmethyl (ViMe) siloxane, silanol-terminated methylphenyl (MePh) siloxane, liquid hydroxyldimethyl-terminated polydiorganosiloxanes containing an average of 2 to 20 diorganosiloxane repeating units per molecule, hydroxyldimethyl-terminated phenylmethylsiloxane, hexaorganodisiloxanes such as hexamethyldisiloxane, divinyltetramethyldisiloxane; hexamethyldisilazane; hexaorganodisilazanes such as divinyltetramethyldisilazane, and tetramethyldi(trifluoropropyl)disilazane; hydroxyldimethyl-terminated polydimethylmethylvinylsiloxane, octamethylcyclotetrasiloxane, and silanes including, but not limited to, methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, chlorotrimethylsilane, dichlorodimethylsilane, and trichloromethylsilane.

[0046] A small amount of water may be added along with the silica treating agent as a processing aid.

[0047] In one embodiment, the required starting compounding ingredient / component (c) herein comprises a dialkylhydroxy or dialkylalkoxy terminated short chain linear or branched polydiorganosiloxane, which comprises a plurality of units of the following structure: -((R 10 )2SiO)-, In the formula, each R 10 are the same or different and are alkyl groups having 1 to 10 carbons, alternatively alkyl groups having 1 to 6 carbons, alternatively methyl, ethyl, or propyl, alternatively aromatic groups having 6 to 12 carbons, alternatively phenyl, and the number average degree of polymerization ranges from 2 to 50, alternatively 2 to 25. In one embodiment, each R 10 is selected from methyl, ethyl, propyl, and phenyl. Each terminal alkoxy group, when present, typically has 1 to 6 carbons, and is preferably ethoxy or methoxy. Thus, the short-chain linear or branched polydiorganosiloxane may be selected from dimethylhydroxy-, dimethylmethoxy-, or dimethylethoxy-terminated polydimethylsiloxanes having a number-average degree of polymerization of 2 to 25, alternatively 2 to 20; dimethylhydroxy-, dimethylmethoxy-, or dimethylethoxy-terminated polymethylphenylsiloxanes having a number-average degree of polymerization of 2 to 25, alternatively 5 to 20; and / or dimethylhydroxy-, dimethylmethoxy-, or dimethylethoxy-terminated polydimethylmethylphenylsiloxane copolymers having a number-average degree of polymerization of 2 to 25, alternatively 2 to 20, such as HO-((R 10 )2SiO) x -H, In the formula, x is the number average degree of polymerization.

[0048] Molecular weight values ​​can also be determined by gel permeation chromatography, but polymers at the lower end of the range, for example, having a DP of about 2 to 20, can be analyzed by gas chromatography mass spectrometry (GC-MS).

[0049] The surface treatment of the untreated silica reinforcing filler (b) can be carried out prior to its introduction into the composition, or in situ, i.e., in the presence of at least a portion of the other ingredients of the compositions herein, by blending these ingredients together at about 25° C. or above until the filler is fully treated. Typically, the untreated silica reinforcing filler (c) is treated in situ with a treating agent in the presence of component (a), resulting in the preparation of a non-catalyzed (fluoro)silicone rubber substrate as described above.

[0050] Component (c) may be present in an amount of 0.1 to 20% by weight of the total base starting formulation components, alternatively 0.5 to 15% by weight of the total base starting formulation components, alternatively 1 to 10% by weight of the total base starting formulation components.

[0051] Optional Base Formula Ingredients Optionally, a small amount of water, for example, up to 3 weight percent of the total base starting formulation components, can be added together with component (c) as a processing aid to promote hydrolysis and enhance processing effectiveness, especially when component (c) is a hexaorganodisilazane such as hexamethyldisilazane (HMDZ).

[0052] If desired or deemed necessary, additional silicone polymers, fluorosilicone polymers or copolymers thereof of the structure defined for component (a) may additionally be incorporated into the substrate during step (i), step (v) or steps (i) and (v) of the present process. These may be rubbers having a Williams plasticity of less than 100 mm / 100 and / or silicone polymers, fluorosilicone polymers or copolymers thereof having a viscosity of 10,000 mPa s at 25°C to 500,000 mPa s at 25°C, the viscosity being measured using a Brookfield® rotational viscometer with spindle LV-4 (designed for viscosities in the range of 1,000 to 2,000,000 mPa s), the speed adapted according to the polymer viscosity, e.g., 6 rpm, and the vinyl content not exceeding a maximum of 10% by weight of each respective polymer.

[0053] If added, the cumulative total amount of such additional silicone polymer, fluorosilicone polymer, or copolymer thereof that may be added in step (i), step (v), or steps (i) and (v) is 10% by weight of the total base starting formulation components, alternatively, in an amount up to 7.5% by weight of the total base starting formulation components, alternatively, in an amount up to 5.0% by weight of the total base starting formulation components.

[0054] For the avoidance of doubt, total base starting formulation ingredients are starting formulation ingredients (a), (b), (c) and any additional formulation ingredients introduced to form the base composition / mixture.

[0055] The process herein for making a non-catalyzed (fluoro)silicone rubber substrate provides the following steps: (i) introducing, as a first starting compounding component, one or more silicone polymers, fluorosilicone polymers or copolymers thereof, in each case having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, into the mixing chamber of a mixer at about 25°C, optionally in an inert atmosphere, and mixing; (ii) gradually introducing one or more reinforcing fillers, as a second starting formulation component, and optionally a third starting formulation component, one or more hydrophobizing filler treating agents, into the mixing chamber of the mixer, while continuing mixing until the mixer is charged with a predetermined amount of reinforcing fillers, that is at least 38% by weight of the total base starting formulation components, to form a base mixture; (iii) optionally maintaining the temperature of the substrate mixture in the mixing chamber within a predetermined range of 100-200°C for a period of up to 6 hours to remove volatile materials from the substrate mixture of step (ii) to form the substrate mixture of step (iii), which step (iii) may be performed under vacuum, if utilized; (iv) cooling the obtained base mixture of step (ii) or the base mixture of step (iii) to a temperature of 25°C to 120°C before, during or after step (iv); (v) reducing the weight percent of reinforcing filler in the base mixture of step (ii) or the base mixture of step (iii) to a predetermined amount by blending the base mixture of step (ii) or the base mixture of step (iii) with one or more additional silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 to form a non-catalyzed (fluoro)silicone rubber substrate.

[0056] Step (v) can be carried out before step (iv), during step (iv), or after step (iv).Typically, step (v) is carried out before or during step (iv) as needed when a substrate is produced.When producing the (fluoro)silicone rubber compound composition described herein, the above step (v) is essential, and there is an additional step (vi) carried out simultaneously with or after step (v).Step (vi) is: (vi) introducing at least one catalyst or vulcanizing agent, and optionally one or more additives selected from crosslinking agents, cure inhibitors, additional fillers, pigments, property modifiers, and the like.

[0057] Focusing on the production of the (fluoro)silicone rubber substrate, as indicated above, the mixer utilized for at least steps (i), (ii) and (iii) is a conical screw dump extruder equipped with a conical twin-screw mixing chamber containing two counter-rotating conical screws converging towards an extrusion die having an inlet and an outlet, the flow path through the extrusion die being controlled by an obturator means whereby the outlet of the extrusion die is adapted to be closed by the obturator means until the end of steps (iii), (iv) or (v), as appropriate, and, where appropriate, adapted to be opened after a selected one of steps (iii), (iv) or (v), depending on whether or when the uncatalyzed (fluoro)silicone rubber substrate is to be further processed or stored outside the conical screw dump extruder.

[0058] The blocking means is in the form of a plate that can be moved between an open position and a closed position. In the closed position, the blocking means is designed to prevent the contents of the conical screw dump extruder from exiting during the non-catalyzed (fluoro)silicone rubber substrate production process, and in the open position, the blocking means is designed to allow the non-catalyzed (fluoro)silicone rubber substrate product to exit through the extrusion die. The two intermeshing conical screws operate in a counter-rotating manner and are driven by a motor that forms part of the conical screw dump extruder. The intermeshing conical screws may be equipped with lip seals on their shafts, if desired. The conical screw dump extruder may be equipped with multiple inlets, for example, for rubber, reinforcing fillers, and processing agents. In each case, these compounding ingredients can be stored in any suitable manner before being introduced into the conical screw dump extruder. They may also be designed so that predetermined amounts of them can be periodically introduced into the conical screw dump extruder mixing chamber for mixing and preparing the non-catalyzed (fluoro)silicone rubber substrate. The starting compounding components for the non-catalyzed (fluoro)silicone rubber substrate manufacturing process can be maintained in an inert atmosphere, typically a nitrogen atmosphere. Furthermore, the mixing chamber of the conical screw dump extruder can be purged with nitrogen before the introduction of the starting compounding components (a), (b), and (c), and during the preparation of the non-catalyzed (fluoro)silicone rubber substrate after the filler has been fully introduced into the mixer. Furthermore, conical screw dump extruders typically have a clamshell-type opening design that allows for easy cleaning, if necessary, during use as a conical screw dump extruder. It has also been found that little or no draining and scraping is required between polymer batch preparations due to the small loss of overall batch weight 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 starting compounding components and by-products involved in the polymerization process described herein.

[0059] Additionally, the conical screw dump extruder may have an integrated vacuum system that allows for the use of a vacuum during the removal of volatiles in step (iii). Examples of such conical screw dump extruders are described in U.S. Pat. No. 7,556,419 and U.S. Patent Application Publication No. 2021 / 113975, both of which are incorporated herein by reference, and such conical screw dump extruders are commercially available from Colmec SpA (Busto Arsizio, Italy).

[0060] In the process described herein, during mixing, the base mixture is driven by a pair of counter-rotating conical screws toward an extrusion die and then forced back when the extrusion die is closed by a closure means. This mixing means appears to unexpectedly and surprisingly be capable of incorporating greater amounts of filler into the rubber than conventional mixers.

[0061] Conventional mixers used to prepare (fluoro)silicone rubber substrates, such as Banbury mixers or Sigma blade mixers, appear to be only capable of incorporating a maximum of about 35% by weight of reinforcing silica filler into the substrate to produce rubber. If more filler is introduced into the mixer, the filler will not be fully incorporated into the rubber, and the rubber / filler mixture will tend to crumble and never clump together. Typically, the excess filler is either extracted through a vent or remains in powder form in the mixing chamber, contributing to the silicone rubber substrate not clumping.

[0062] It is believed that the maximum value of 35 wt.% can be attributed to, for example, the mixing mechanism of a sigma blade, where as the initial mixing occurs, the material is "grabbed" and drawn into the mixing trough for mixing, which becomes increasingly difficult as the viscosity / Williams plasticity increases, and the partially prepared base material becomes too hard to draw the remainder into the base material composition, or, given the mixing mechanism of the mixer used, the base material becomes powdery due to its inability to be re-agglomerated as the filler loading increases to functional saturation levels. Surprisingly, it is believed that the process described herein allows for greater percentages of filler to be incorporated into the rubber without such problems.

[0063] In step i) of the process for producing a (fluoro)silicone rubber substrate, one or more silicone polymers, fluorosilicone polymers or copolymers thereof ((fluoro)silicone gums), in each case having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, are introduced into a conical twin-screw mixing chamber through a suitable inlet.

[0064] The (fluoro)silicone gum is generally introduced at about 25°C, after which the gum is mixed. In use, the (fluoro)silicone gum or gums introduced into the mixing chamber of the conical twin-screw extruder are driven toward the extrusion die by the counter-rotating screws. However, when the closure is closed, they are forced back into the mixing chamber for further recirculation / additional mixing to enhance the homogeneity of the (fluoro)silicone gum. The two counter-rotating screws are in converging and intersecting conical channels, with the peripheral contours of the screw threads extending adjacent to the channel surfaces. Thus, the material is forced into a gradually narrower volume along the conical contours of the screws, and the pressure of the (fluoro)silicone gum increases as it approaches the closed extrusion die prior to the preparation of the substrate in step (ii). This can optionally be carried out in an inert atmosphere. The materials introduced into the conical twin-screw extruder gradually heat up during the preparation of the non-catalyzed (fluoro)silicone rubber substrate due to shear heating during the (fluoro)silicone rubber substrate manufacturing process, and can reach temperatures up to nearly 200°C.

[0065] The (fluoro)silicone gum introduced into the mixing chamber of the conical twin-screw extruder in step (i) can be introduced in any suitable manner, for example manually or otherwise from any suitable container or using an automatic introduction process, such as an automatic introduction process with an auger from a gum hopper, etc. When mixed under an inert atmosphere, the (fluoro)silicone rubber substrate manufacturing process is typically carried out in a nitrogen atmosphere.

[0066] When two or more (fluoro)silicone gums (a) are used, they may be premixed in a suitable mixer before entering the conical twin-screw extruder, if desired, so that the different (fluoro)silicone gums (a) are thoroughly intermixed when introduced into the conical twin-screw extruder. Alternatively, when two or more (fluoro)silicone gums (a) are utilized, the respective (fluoro)silicone gums (a) may be introduced into the conical screw dump extruder simultaneously or by any other suitable mixing regime, for example, by introducing one (fluoro)silicone gum (a) at the beginning of the (fluoro)silicone rubber substrate manufacturing process and introducing aliquots of a second (fluoro)silicone gum (a) periodically during the (fluoro)silicone rubber substrate manufacturing process, or by introducing a quantity of a first (fluoro)silicone gum (a), followed by a quantity of a second (fluoro)silicone gum (a), and repeating as appropriate. These gums can then be thoroughly mixed together in a conical twin-screw extruder prior to the introduction of reinforcing filler (b) and treating agent (c) (if the latter is required to prepare a non-catalyzed (fluoro)silicone rubber substrate).

[0067] In step (ii) of the (fluoro)silicone rubber substrate manufacturing process, one or more reinforcing fillers and, optionally, one or more hydrophobizing filler treating agents are gradually introduced into the conical twin-screw extruder while continuing mixing until a predetermined amount of reinforcing filler is introduced, typically 38% by weight based on the weight of all base starting ingredients, typically 39-55%, alternatively 39-50%, alternatively 39-45% by weight based on the weight of all base starting ingredients, to form the base mixture. The reinforcing filler (b) can be introduced into the conical twin-screw extruder via any suitable powder introduction means compatible therewith. For example, it can be introduced via one or more hoppers or manually from a bag or the like. The treating agent (c), if necessary, can be automatically dosed using any suitable means, for example, from a tank, or manually if desired. Typically, if a treating agent (c) is required, as would be expected in most cases, the reinforcing filler (b) and the treating agent (c) can be introduced into the conical twin-screw extruder in any order, i.e., one before the other, or simultaneously. They can both be introduced gradually at a predetermined rate or periodically during the mixing process, if desired. The mixing in step (ii) of the (fluoro)silicone rubber substrate manufacturing process can also be carried out in a nitrogen atmosphere, for example, by periodically introducing nitrogen to control the oxygen level in the mixer during mixing.

[0068] In step (ii) of the manufacturing process for the (fluoro)silicone rubber substrate, a conical screw dump extruder is utilized to introduce reinforcing filler (b) into the (fluoro)silicone gum(s) (a), and said reinforcing filler (b) is treated in situ with a treating agent (c) to make the outer surface of the reinforcing filler hydrophobic and therefore more easily wetted by and introduced into the (fluoro)silicone gum(s) (a).

[0069] In use, assuming that a treating agent (c) is required, components (b) and (c) are introduced into a conical screw dump extruder that already contains component (a). The compounding ingredients for preparing the substrate, i.e., components (a), (b), and (c), are then mixed in the same manner as described above for step (i), i.e., in the conical screw dump extruder mixing chamber, and they are driven toward the extrusion die by the counter-rotating screws with the obturator closed, so that they are forced back into the conical twin-screw mixing chamber for further recirculation / additional mixing, enhancing the uniformity of the non-catalyzed (fluoro)silicone rubber substrate as it is being prepared. The two counter-rotating screws are in converging, intersecting conical channels, with the peripheral contours of the screw threads extending adjacent to the channel surfaces. Thus, the material is forced into a progressively narrower volume along the conical profile of the screw, and pressure increases as the compounding ingredients and / or the non-catalyzed (fluoro)silicone rubber substrate product approach the closed extrusion die during the non-catalyzed (fluoro)silicone rubber substrate production process. This pressure increase allows for recirculation of the contents of the mixing chamber. If desired, for example, perhaps when the non-catalyzed (fluoro)silicone rubber substrate production process is considered nearly complete, the rotation of the two screws can be temporarily reversed to aid in the mixing or cooling process. Polytetrafluoroethylene (PTFE) packing can be utilized on the shaft of the conical screw, and in one embodiment, the screw can be equipped with a lip seal on the shaft of the screw, if desired. Typically, step ii) of the non-catalyzed (fluoro)silicone rubber substrate production process is usually carried out at a temperature of about 50°C to 120°C, alternatively about 50°C to 100°C, or alternatively about 50°C to 80°C, depending on the hydrophobizing agent (c) utilized.Chain extension is not often utilized when making substrates from (fluoro)silicone gums, but if for some reason chain extension is required it is typically performed during step (ii); therefore, if required, a chain extender can be added to the conical screw dump extruder during step (ii) of the process to effect chain extension during step (ii) and / or step (iii) of the process for making the substrate.

[0070] In step (iii) of the (fluoro)silicone rubber substrate manufacturing process, the temperature of the mixing chamber is optionally maintained within a predetermined range of 100-200°C for up to six hours to remove volatiles and thermodynamically promote the silica treatment. If utilized, step (iii) may be performed under vacuum; heating may be required if the heat generated during shear mixing in step (ii) does not generate enough heat to ensure that the temperature in step (iii) is maintained within the desired range while the volatiles are removed. Volatiles generated during step (ii) of the (fluoro)silicone rubber substrate manufacturing process are removed, and mixing can continue. Depending on the volatiles believed to be present due to the compounding ingredients used, particularly the treating agent (c) used, the conical twin-screw extruder mixing chamber may be maintained at a suitable temperature, i.e., within a predetermined range of 100-200°C, for up to six hours to remove volatiles as needed.

[0071] In step (iv) of the (fluoro)silicone rubber substrate manufacturing process, the resulting substrate mixture of step (ii) and optional step (iii) is cooled to a temperature of 25°C to 120°C, thereby providing a non-catalyzed (fluoro)silicone rubber substrate containing at least 38 wt% reinforcing filler, which can be further processed or stored. The temperature to which the non-catalyzed (fluoro)silicone rubber substrate needs to be cooled depends on whether it is to be used for further processing, i.e., compounding, in which a catalyst and optional additives are introduced, or whether the non-catalyzed (fluoro)silicone rubber substrate is to be packaged, for example, for future use or sale.

[0072] Therefore, for example, when a non-catalyzed (fluoro)silicone rubber substrate is stored and / or packaged, it must be cooled to a temperature low enough to prevent melting of the packaging material, e.g., in the case of polyethylene, it must be cooled to a temperature of 90°C or less, and can be cooled to a predetermined temperature of, for example, about 30°C to 80°C, or about 30°C to 70°C, or about 40°C to 70°C. The cooling step (iv) of the (fluoro)silicone rubber substrate production process can be, for example: (I) entirely in the conical screw dump extruder used to make the non-catalyzed (fluoro)silicone rubber substrate, in which case the resulting non-catalyzed (fluoro)silicone rubber substrate is extruded at low temperatures, in the range of 30-40°C; or (II) partially in a conical screw dump extruder used to make the non-catalyzed (fluoro)silicone rubber substrate, in which case the resulting non-catalyzed (fluoro)silicone rubber substrate is extruded at moderate temperatures in the range of 50-80°C and then transferred to an alternative means for further cooling, such as a pan or other container; or (III) entirely outside of the conical screw dump extruder used to make the non-catalyzed (fluoro)silicone rubber substrate, in which case the resulting non-catalyzed (fluoro)silicone rubber substrate is "hot" extruded at a temperature of 80°C to 120°C, alternatively at a temperature of 90°C to 120°C, and then transferred to an alternative means for cooling, such as a second "cooled" conical screw dump extruder, pan, or other container, in which case the conical screw dump extruder used to make the non-catalyzed (fluoro)silicone rubber substrate can be reused to make additional batches of non-catalyzed (fluoro)silicone rubber substrate from components (a), (b), and (c) without delay.

[0073] If a conical screw dump extruder used to make non-catalyzed (fluoro)silicone rubber substrates is also used to cool the substrate to about 25°C, costs and time may increase and plant production may decrease, resulting in options (iv)(II) and (iv)(III) being preferred.

[0074] Optional step (v) may be carried out before, during or after step (iv). Typically, step (v) is carried out before or during step (iv), as needed, when the substrate is prepared.

[0075] If desired, after step (iv) or (v), the resulting product of step (iv) or step (v) may be pelletized or dusted with a suitable powder before storage to facilitate future use, for example, as a major component in a compounding process. Any suitable process may be used to pelletize the product, and the resulting pelletized product may be considered a preferred storage medium before being used in compounding. Similarly, or alternatively, the base composition may be dusted with a suitable powder, such as talcum powder, to facilitate future use after storage.

[0076] However, in one embodiment, the conical screw dump extruder used to make the non-catalyzed (fluoro)silicone rubber substrate may also be used to make the non-catalyzed (fluoro)silicone rubber substrate, and then step (iv)(I) may be utilized to compound the cooled non-catalyzed (fluoro)silicone rubber substrate with other additives in the conical screw dump extruder prior to extrusion. In such a case, the blocking means is maintained in the closed position during the non-catalyzed (fluoro)silicone rubber substrate manufacturing process, for example, during steps (i)-(iii) above and this step (iv), as well as steps (v) and (vi) described above for compounding.

[0077] Subsequently, when the non-catalyzed (fluoro)silicone rubber substrate product of step (iii) has cooled to the desired temperature for removal from the conical screw dump extruder used to make the non-catalyzed (fluoro)silicone rubber substrate, the closure means is moved to an open position to allow the resulting non-catalyzed (fluoro)silicone rubber substrate product to be extruded through an extrusion die having an inlet and an outlet, and the flow path through the extrusion die from the inlet to the outlet of the conical screw dump extruder is controlled by the closure means.

[0078] The uncatalyzed (fluoro)silicone rubber base product exiting the conical screw dump extruder through the extrusion die is either collected for further cooling and / or step (v), or collected and transferred to suitable packaging means, or conveyed to a compounding means to undergo steps (v) and (vi) above, i.e., to produce a curable rubber compound composition, etc. If further cooled, it can be extruded into bulk tubs or other containers, or flow directly to a gear pump and then packaged.

[0079] In one embodiment, the substrate exiting the conical screw dump extruder is extruded to another apparatus for further processing, such as step (v) above and optional step (vi), where it is filtered and packaged, using a conical screw dump extruder equipped with a gear pump or a tapered twin screw extruder, or alternatively using any suitable compounding means such as a sigma blade kneader-mixer, a bottom discharge kneader-mixer, a conical screw dump extruder, a planetary extruder, a co-kneader-extruder, a twin screw extruder, a single screw extruder and / or a two-roll mill (in this case, in a preferred embodiment, this may be a second conical screw dump extruder).

[0080] In one embodiment, the process for preparing the non-catalyzed (fluoro)silicone rubber substrate forms part of a continuous compounding process; for example, a first conical screw dump extruder may be used to prepare the silicone rubber rubber as described in WO 2023 / 219834; a second conical screw dump extruder may be utilized to make the non-catalyzed (fluoro)silicone rubber substrate as described above; a third conical screw dump extruder may be utilized at least partially for cooling step (iv) and subsequent packaging, or partially for cooling steps (iv) and steps (v) and optional (vi); or there may be a cascade of conical screw dump extruders used, in that the third conical screw dump extruder can extrude the cooled non-catalyzed (fluoro)silicone rubber substrate together with the catalyst and other additives into a fourth conical screw dump extruder which can be utilized for steps (v) and (vi) to form the curable silicone rubber compound composition.

[0081] Typically, when compounding a non-catalyzed (fluoro)silicone rubber substrate as described above, step (v) is performed first, with an additional amount of (fluoro)silicone gum being introduced and mixed with the resulting product of step (iv). The amount of additional (fluoro)silicone gum is predetermined to ensure an appropriate level of filler is present in the final compound composition resulting from step (vi). If desired, one or more of the organopolysiloxane polymers identified above as additional substrate compounding ingredients may be additionally introduced during step (v). Thus, if such optional compounding ingredients are present, they are typically introduced to the substrate during steps (i), (ii), or (v), or between steps (i) and (v). If appropriate, step (v) may be performed, and the product of step (v) may then be packaged and stored so that step (vi) can be performed later, either in-house or by a third party. Alternatively, step (vi) may be performed simultaneously with step (v) or after step (v) using the product of step (v).

[0082] The catalyst, crosslinker, and optional additives, if required, are ideally all charged depending on the equipment utilized, although small amounts of additives may be introduced manually if desired, although this is typically not preferred.

[0083] After the cooling step (iv), compounding of the non-catalyzed (fluoro)silicone rubber substrate must be carried out at a temperature below the cure temperature of the catalyst, typically a peroxide, which is one of the additives commonly used during compounding. Thus, compounding is preferably carried out at a temperature below 50°C for most peroxides, but can be carried out at temperatures up to about 120°C for some catalysts.

[0084] The compounding means used in step (vi) 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 a preferred embodiment may be a second conical screw dump extruder.

[0085] Once the above process is complete, the resulting uncatalyzed (fluoro)silicone rubber substrate can be stored for future use or utilized to make a curable compound composition by introducing catalysts, crosslinkers, etc., into the substrate.

[0086] First, the non-catalyzed (fluoro)silicone rubber substrate may be diluted by introducing an additional amount of one or more (fluoro)silicone gum(s) defined as component (a) above, optionally along with one or more of the organopolysiloxane polymers identified as additional base compounding ingredients, to reduce the filler content in the non-catalyzed (fluoro)silicone rubber substrate before introducing other additives. Any suitable amount of (fluoro)silicone gum(s) may be introduced as needed and when necessary. In fact, the non-catalyzed (fluoro)silicone rubber substrate may, if desired, be diluted with (fluoro)silicone gum(s) different from those originally utilized to make the non-catalyzed (fluoro)silicone rubber substrate.

[0087] Typically, when using non-catalyzed (fluoro)silicone rubber substrates made from silicone gum and / or fluorosilicone polymer rubber, the preferred catalyst used is a suitable organic peroxide or a selection thereof.Suitable organic peroxides include substituted or unsubstituted dialkyl-, alkylaroyl-, and diaroyl peroxides, such as benzoyl peroxide and 2,4-dichlorobenzoyl peroxide, ditertiary butyl peroxide, dicumyl peroxide, t-butylcumyl peroxide, bis(tert-butyldioxy)diisopropylbenzenebis(t-butylperoxy)-2,5-dimethylhexyne2,4-dimethyl-2,5-di(t-butylperoxy)hexane, di-t-butyl peroxide, and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane.Mixtures of the above can also be used.

[0088] Typically, the amount of free radical curative utilized in the high consistency rubber compositions described herein is from 0.2 to 3 weight percent, alternatively from 0.2 to 2 weight percent, in each case based on the weight of the composition.

[0089] Alternatively, but less preferred for such substrate materials, (i) a crosslinker in the form of an organosilicon compound having at least two, alternatively at least three, Si—H groups per molecule; and (ii) a hydrosilylation cure package comprising a hydrosilylation catalyst comprising or consisting of a platinum group metal or a compound thereof.

[0090] Organosilicon compound (i) functions as a crosslinker and is provided in the form of an organosilicon compound having at least two, or alternatively at least three, Si-H groups per molecule. The organosilicon compound (i) of the liquid silicone rubber composition typically contains three or more silicon-bonded hydrogen atoms, so that the hydrogen atoms can react with the unsaturated alkenyl and / or alkynyl groups of component (a) to form a network therewith, thereby curing the composition. Alternatively, if polymer (a) has more than two unsaturated groups per molecule, some or all of organosilicon compound (i) can have two silicon-bonded hydrogen atoms per molecule.

[0091] The molecular configuration of the organosilicon compound (organosilicon compound (i)) having at least two or at least three Si-H groups per molecule is not particularly limited. It may be a polyorganosiloxane, which may have a linear chain, a branched chain (a linear chain with some branches through the presence of T groups), a cyclic chain, or may be a silicone resin-based system.

[0092] The molecular weight of organosilicon compound (i) is not particularly limited, but the viscosity is typically 5 to 50,000 mPa.s at 25°C using the test methodology described for component (a).

[0093] The silicon-bonded organic group used in the organosilicon compound (i) can be exemplified by alkyl groups such as methyl, ethyl, propyl, n-butyl, t-butyl, pentyl, hexyl, etc.; aryl groups such as phenyl, tolyl, xylyl, or similar aryl groups; 3-chloropropyl, 3,3,3-trifluoropropyl, or similar halogenated alkyl groups, and is preferably an alkyl group having 1 to 6 carbon atoms, particularly a methyl, ethyl, or propyl group, or a phenyl group. Preferably, the silicon-bonded organic group used in the organosilicon compound (i) is an alkyl group, or a methyl, ethyl, or propyl group.

[0094] Examples of organosilicon compounds (c1(i)) having at least two, or alternatively at least three Si—H groups per molecule of organosilicon compound (i) include, but are not limited to, the following: (a') trimethylsiloxy-terminated methylhydrogenpolysiloxane, (b') trimethylsiloxy-terminated polydimethylsiloxane-methylhydrogensiloxane; (c') dimethylhydrogensiloxy-terminated dimethylsiloxane-methylhydrogensiloxane copolymer; (d') dimethylsiloxane-methylhydrogensiloxane cyclic copolymer; (e')(CH3)2HSiO 1 / 2 Units: (CH3)3SiO 1 / 2 units, and SiO 4 / 2 copolymers and / or silicone resins consisting of units, (f')(CH3)2HSiO 1 / 2 units, and SiO 4 / 2 copolymers and / or silicone resins consisting of units, (g') methylhydrogensiloxane cyclic homopolymer having 3 to 10 silicon atoms per molecule; Alternatively, the crosslinking organosilicon compound (i) can be a filler such as silica treated with one of the above, and mixtures thereof.

[0095] In one embodiment, the organosilicon compound (i) is selected from the group consisting of methylhydrogenpolysiloxanes terminated at both molecular chain ends with trimethylsiloxy groups; copolymers of methylhydrogensiloxanes terminated at both molecular chain ends with trimethylsiloxy groups and dimethylsiloxanes; dimethylsiloxanes terminated at both molecular chain ends with dimethylhydrogensiloxy groups; and copolymers of methylhydrogensiloxanes terminated at both molecular chain ends with dimethylhydrogensiloxy groups and dimethylsiloxanes.

[0096] The crosslinking agent, organosilicon compound (i), is generally present in the compound composition in an amount such that the molar ratio of the total number of silicon-bonded hydrogen atoms in organosilicon compound (i) to the total number of alkenyl and / or alkynyl groups in component (a) is 0.5:1 to 10:1. If this ratio is less than 0.5:1, a sufficiently cured elastomeric material will not be obtained. If this ratio exceeds 10:1, the hardness of the cured elastomeric material tends to increase when heated. Preferably, organosilicon compound (i) is present in an amount such that the molar ratio of silicon-bonded hydrogen atoms in organosilicon compound (i) to the alkenyl / alkynyl or alkenyl groups in component (a) is in the range of 0.7:1.0 to a maximum of 5.0:1.0, alternatively 0.9:1.0 to 2.5:1.0, or even alternatively 0.9:1.0 to 2.0:1.0.

[0097] The silicon-bonded hydrogen (Si-H) content of organosilicon compound (i) is determined using quantitative infrared analysis in accordance with ASTM E168. In the present invention, the ratio of silicon-bonded hydrogen to alkenyl (vinyl) and / or alkynyl is important when relying on a hydrosilylation curing process. Generally, this is determined by calculating the total weight percent of alkenyl groups, e.g., vinyl [V], in the composition and the total weight percent of silicon-bonded hydrogen [H] in the composition; if the molecular weight of hydrogen is 1 and the molecular weight of vinyl is 27, then the molar ratio of silicon-bonded hydrogen to vinyl is 27 [H] / [V].

[0098] Typically, depending on the number of unsaturated groups in component (a) and the optional base material additive, and the number of Si—H groups in organosilicon compound (i), organosilicon compound (i) is present in an amount of 0.1 to 10 wt % of the compound composition, alternatively 0.1 to 7.5 wt %, alternatively 0.5 to 7.5 wt %, and further alternatively 0.5 wt % to 5 wt % of the compound composition.

[0099] The hydrosilylation catalyst (ii) comprises or consists of a platinum group metal or a compound thereof. They are usually selected from catalysts of platinum group metals (platinum, ruthenium, osmium, rhodium, iridium, and palladium) or compounds of one or more of such metals. Alternatively, platinum and rhodium compounds are preferred due to the high activity levels of these catalysts in hydrosilylation reactions, with platinum compounds being most preferred. In the hydrosilylation (or addition) reaction, the hydrosilylation catalyst (ii) herein catalyzes the reaction between an unsaturated group, usually an alkenyl group, such as vinyl, and an Si-H group.

[0100] The hydrosilylation catalyst (ii) can be a platinum group metal; a platinum group metal deposited on a support, for example, activated carbon, a metal oxide such as aluminum oxide or silicon dioxide, silica gel, or powdered charcoal; or a compound or complex of a platinum group metal. Preferably, the platinum group metal is platinum.

[0101] Examples of preferred hydrosilylation catalysts (ii) are platinum-based catalysts such as platinum black, platinum oxide (Adams' catalyst), platinum on various solid supports, chloroplatinic acid such as hexachloroplatinic acid (Pt oxidation state IV) (Speier's catalyst), chloroplatinic acid in solution in an alcohol such as isooctanol or amyl alcohol (Lamoreaux's catalyst), and complexes of chloroplatinic acid with ethylenically unsaturated compounds such as olefins and organosiloxanes containing ethylenically unsaturated silicon-bonded hydrocarbon groups, such as tetra-vinyl-tetramethylcyclotetrasiloxane-platinum complex (Ashby's catalyst). Usable soluble platinum compounds include, for example, platinum-olefin complexes of the formula (PtCl2.(olefin)2 and H(PtCl3.olefin), and in this context, the use of alkenes having 2 to 8 carbon atoms, such as ethylene, propylene, isomers of butene and isomers of octene, or cycloalkanes having 5 to 7 carbon atoms, such as cyclopentene, cyclohexene, and cycloheptene, is preferred. Other soluble platinum catalysts are, for example, hexachloroplatinic acid and alcohols, ethers, and aldehydes. and platinum-cyclopropane complexes of the formula (PtCl2C3H6)2, which are reaction products of hexachloroplatinic acid and / or its conversion products with vinyl-containing siloxanes such as methylvinylcyclotetrasiloxane in the presence of sodium bicarbonate in an ethanolic solution. Platinum catalysts with phosphorus and amine ligands, e.g., (Ph3P)2PtCl2, and complexes of platinum with vinyl siloxanes such as sym-divinyltetramethyldisiloxane, can also be used.

[0102] Therefore, specific examples of suitable platinum-based catalysts include: (i) complexes of chloroplatinic acid with organosiloxanes containing ethylenically unsaturated hydrocarbon groups, as described in U.S. Pat. No. 3,419,593; (ii) chloroplatinic acid in either the hexahydrate or anhydrous form; (iii) platinum-containing catalysts obtained by a process comprising reacting chloroplatinic acid with an aliphatically unsaturated organosilicon compound such as divinyltetramethyldisiloxane; (iv) alkene-platinum-silyl complexes described in U.S. Pat. No. 6,605,734, such as (COD)Pt(SiMeCl) (where “COD” is 1,5-cyclooctadiene), and / or (v) Karstedt catalysts, platinum divinyltetramethyldisiloxane complexes typically containing about 1% by weight of platinum in a vinylsiloxane polymer having a viscosity of about 200-750 using the test method described for component (a).

[0103] While organic solvents such as toluene have historically been used as alternatives, the use of vinylsiloxane polymers is by far the preferred choice. These are described in U.S. Patent Nos. 3,715,334 and 3,814,730. In a preferred embodiment, the hydrosilylation catalyst (ii) can be selected from platinum coordination compounds. In one embodiment, hexachloroplatinic acid and its conversion products with vinyl-containing siloxanes, Karstedt's catalyst, and Speier's catalyst are preferred.

[0104] The hydrosilylation catalyst (ii) is typically present in an amount of platinum atoms providing 0.1 to 500 ppm (parts per million) based on the weight of the reactive formulation components (a) and (c1(ii)). The catalyst may be added as a single species or as a mixture of two or more different species. Typically, depending on the form / concentration in which the hydrosilylation catalyst (ii) is provided, the amount of catalyst present ranges from 0.05 to 1.5 wt. % of the composition, alternatively from 0.05 to 1.0 wt. % of the composition, alternatively from 0.1 to 1.0 wt. %, alternatively from 0.1 to 0.5 wt. %, and the platinum catalyst is provided in a polymer masterbatch such as (a) above.

[0105] A wide variety of other additives can be added to the non-catalyzed (fluoro)silicone rubber base material during the compounding process.

[0106] Optional Additives In each case, various optional additives suitable for the application in which the elastomer resulting from the cure will be used may also be incorporated into the composition. Examples include cure inhibitors (typically when a hydrosilylation cure package is incorporated), mold release agents, extending fillers, adhesion catalysts, rheology modifiers, electrically conductive fillers, thermally conductive fillers, pot life extenders, acid acceptors, lubricants, heat stabilizers, compression set additives, UV light stabilizers, fungicides, wetting agents, pigments and colorants, flame retardants, and plasticizers.

[0107] Curing inhibitor Cure inhibitors are used when necessary, i.e., when a hydrosilylation (addition) cure system is used rather than a peroxide. Cure inhibitors are used to prevent or slow the addition reaction cure process, especially during storage. Optional addition reaction inhibitors for platinum-based catalysts are well known in the art and include hydrazines, triazoles, phosphines, mercaptans, organic nitrogen compounds, acetylenic alcohols, silylated acetylenic alcohols, maleates, fumarates, ethylenically or aromatic unsaturated amides, ethylenically unsaturated isocyanates, olefinic siloxanes, unsaturated hydrocarbon monoesters and diesters, conjugated ene-ynes, hydroperoxides, nitriles, and diaziridines. Alkenyl-substituted siloxanes, such as those described in U.S. Pat. No. 3,989,667, may also be used, of which cyclic methylvinylsiloxanes are preferred.

[0108] One class of known hydrosilylation reaction inhibitors is the acetylenic compounds disclosed in U.S. Patent No. 3,445,420. Acetylenic alcohols, such as 2-methyl-3-butyn-2-ol, constitute a preferred class of inhibitors, which suppress the activity of platinum-containing catalysts at 25° C. Typically, compositions containing these inhibitors must be heated to temperatures above 70° C. in order to cure at a practical rate.

[0109] Examples of acetylene alcohols and their derivatives include 1-ethynyl-1-cyclohexanol (ETCH), 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-butyn-2-ol, propargyl alcohol, 1-phenyl-2-propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclopentanol, 3-methyl-1-penten-4-yn-3-ol, and mixtures thereof. Derivatives of acetylene alcohols can include those compounds having at least one silicon atom.

[0110] When present, inhibitor concentrations as low as 1 mole of inhibitor per mole of catalyst metal provide satisfactory storage stability and cure rates. In other cases, inhibitor concentrations of up to 500 moles of inhibitor per mole of catalyst metal are required. The optimum concentration for a given inhibitor in a given composition is readily determined by routine experimentation. Depending on the concentration and form in which the selected inhibitor is commercially provided / available, inhibitors, if present in the composition, are typically present in amounts of 0.0125 to 10 weight percent of the composition.

[0111] In one embodiment, the inhibitor, if present, is selected from 1-ethynyl-1-cyclohexanol (ETCH) and / or 2-methyl-3-butyn-2-ol and is present in an amount greater than 0 to 0.1% by weight of the composition.

[0112] release agent Any suitable release agent may be utilized, such as a hydroxydimethyl-terminated polydimethylsiloxane having a viscosity of 100-200 mPa.s at 25° C. as measured using a Brookfield™ rotational viscometer at 12 rpm using a cone-plate configuration with cone CP-52.

[0113] Bulking filler Expanding fillers may include ground quartz, diatomaceous earth, barium sulfate, iron oxide, titanium dioxide, and carbon black, talc, wollastonite, etc. Other fillers that may be used alone or in addition to the above include clays such as aluminite, calcium sulfate (anhydrite), gypsum, calcium sulfate, kaolin, aluminum trihydroxide, graphite, copper carbonates such as malachite, nickel carbonates such as zarachite, barium carbonates such as witherite, and / or strontium carbonates such as strontium stone.

[0114] Other expanding fillers may include aluminum oxide, silicates from the group consisting of the olivine family; the garnet family; aluminosilicates; cyclic silicates; chain silicates, and layer silicates. The olivine family includes silicate minerals such as, but not limited to, forsterite and Mg2SiO4. The garnet family includes red garnet; Mg3Al2Si3O 12 ; green garnet; and Ca2Al2Si3O 12 Aluminosilicates include, but are not limited to, ground silicate minerals such as sillimanite; Al2SiO5; mullite; 3Al2O3.2SiO2; kyanite; and Al2SiO5. Cyclic silicates may also be utilized as expanding fillers, including cordierite and Al3(Mg,Fe)2[Si4AlO 18 The chain silicate family includes, but is not limited to, ground silicate minerals such as wollastonite and Ca[SiO3]. Layered silicates may alternatively or additionally be used as extending fillers, and suitable groups include silicate minerals such as mica; K2AI; 14 [Si6Al2O 20 ](OH)4;phyllite;Al4[Si8O 20 ](OH)4; talc, Mg6[SiO 20 ](OH)4; serpentine, e.g. asbestos; kaolinite; Al4[Si4O 10 ](OH)8; and vermiculite.

[0115] Adhesion promoter The composition may also comprise one or more monoacrylates, diacrylates, or methacrylates; epoxy-containing alkoxysilanes, amine-containing alkoxysilanes, alkoxysilanes containing methacryl or acrylic groups, and i) one or more alkoxysilanes having an epoxy group in the molecule; ii) a linear organopolysiloxane oligomer containing at least one alkenyl group and at least one hydroxy or alkoxy group per molecule; iii) an organometallic condensation reaction catalyst comprising an organoaluminum compound or an organozirconium compound; or a mixture and / or reaction product thereof.

[0116] Rheology Modifiers The composition may also include a rheology modifier such as polytetrafluoroethylene (PTFE).

[0117] Pigments and other colorants Examples of pigments include titanium dioxide, chromium oxide, bismuth vanadium oxide, iron oxide, and mixtures thereof.

[0118] Examples of colorants that can be used in the hydrosilylation-curable silicone coating composition include pigments, vat dyes, reactive dyes, acid dyes, chrome dyes, disperse dyes, cationic dyes, and mixtures thereof. The dual moisture-curable organopolysiloxane compositions described herein can further include one or more pigments and / or colorants, which can be added as needed. The pigments and / or colorants can be colored, white, black, metallic effect, and luminescent, such as fluorescent and phosphorescent. Pigments are used as needed to color the composition. Any suitable pigment may be used as long as it is compatible with the compositions herein. In dual moisture-curable organopolysiloxane compositions, pigments and / or colored (non-white) fillers, such as carbon black, may be used in the catalyst package to color the end sealant product.

[0119] Suitable white pigments and / or colorants include titanium dioxide, zinc oxide, lead oxide, zinc sulfide, lithopone, zirconium oxide, and antimony oxide.

[0120] Suitable non-white inorganic pigments and / or colorants include, but are not limited to, goethite, lepidocrocite, hematite, maghemite, and magnetite; iron oxide pigments such as black iron oxide, yellow iron oxide, brown iron oxide, and red iron oxide; blue iron pigments; chromium oxide pigments; cadmium pigments such as cadmium yellow, cadmium red, cadmium cinnabar; bismuth pigments such as bismuth vanadate and bismuth vanadate molybdate; mixed metal oxide pigments such as cobalt titanate green; chromate and molybdate pigments such as chrome yellow, molybdate red, and molybdate orange; ultramarine pigments; cobalt oxide pigments; nickel antimony titanate; lead chromium; carbon black, lamp black, and metallic effect pigments such as aluminum, copper, copper oxide, bronze, stainless steel, nickel, zinc, and brass.

[0121] Suitable organic non-white pigments and / or colorants include phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; monoarylide yellow, diarylide yellow, benzimidazolone yellow, heterocyclic yellow, DAN orange, quinacridone pigments such as quinacridone magenta and quinacridone violet, organic reds including metallized azo reds and non-metallized azo reds and other azo pigments, monoazo pigments, diazo pigments, azo pigment lakes, β-naphthol pigments, naphthol AS pigments, benzimidazolone pigments, diazo condensed pigments, isoindolinone and isoindoline pigments, polycyclic pigments, perylene and perinone pigments, thioindigo pigments, anthrapyrimidone pigments, flavanthrone pigments, anthanthrone pigments, dioxazine pigments, triarylcarbonium pigments, quinophthalone pigments, and diketopyrrolopyrrole pigments.

[0122] Typically, the pigment and / or colorant, when in the form of fine particles, has an average particle size in the range of 10 nm to 50 μm, preferably in the range of 40 nm to 2 μm.

[0123] lubricant Typically, if present, lubricants that can be added to the compound composition include polyphenylmethylsiloxanes and copolymers thereof, such as trimethylsilyl-terminated phenylmethylsiloxane dimethylsiloxane copolymers, having a viscosity of 100 mPa·s to 200 mPa·s at 25°C using a Brookfield™ rotational viscometer in cone-plate configuration with a CP-52 cone at 12 rpm, and mixtures or derivatives thereof. Examples of other lubricants that can be utilized alternatively or additionally include tetrafluoroethylene, resin powders, graphite, fluorinated graphite, talc, boron nitride, fluorinated oils, molybdenum disulfide, and mixtures or derivatives thereof. If present, such lubricants can be present in an amount of 1 to 7% by weight of the composition.

[0124] heat stabilizer The compositions herein may also include one or more inorganic heat stabilizers, used alone or in combination, such as hydrated cerium oxide, cerium hydroxide, cerium carboxylates and / or cerium esters such as cerium ethylhexanoate, hydrated aluminum oxide, red iron oxide, yellow iron oxide, carbon black, graphite, and zinc oxide.

[0125] metal deactivator The composition can incorporate one or more metal deactivators selected from diacylhydrazide compounds, aminotriazole compounds, and amino-containing triazine compounds, such as N,N'-bis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl]hydrazine, sold by BASF as Irganox™ MD1024; dodecandioyl-di-(N'-salicyloyl)hydrazine, which is a synonym for 1-N',12-N'-bis(2-hydroxybenzoyl)dodecanedihydrazide, sold by Adeka Corporation as ADK STAB™ CDA-6; N'1,N'12-bis(2-hydroxybenzoyl)dodecanedihydrazide, sold by Adeka Corporation as ADK STAB™ CDA-6S; and ADK STAB™ CDA-6S, sold by Adeka Corporation. Examples include N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, commercially available as STAB™ CDA-10, and N,N'-bis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionylhexamethylenediamine, commercially available as ANTAGE HP-300 from Kawaguchi Chemical Industry Co., Ltd. They may also include the following: An example of a commercially produced compound of this type is 3-(n-salicyloyl)amino-1,2,4-triazole (its synonym is 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide), which is commercially available from Adeka Corporation as ADK STAB™ CDA-1 and in blends as ADK STAB™ CDA-1M, or from Adeka Corporation as Adekastab™ ZS-27, the major component of which is understood to be 2,4,6-triamino-1,3,5-triazine.

[0126] Before use, the selected organocyclosiloxane oligomer is stored in a suitable storage container or delivered directly from production. When the selected organocyclosiloxane oligomer(s) are delivered to a storage container in which the product is directly stored for immediate use, or delivered to such a storage container for immediate use, any of the optional additives described above can be added to the substrate if desired, but this is not usually done. They are usually added to the substrate during the compounding process, along with the catalyst in the case of a hydrosilylation curing crosslinker. The catalyst and crosslinker are not added during the preparation of the substrate herein.

[0127] In one embodiment, if desired, after step (iv) or (v), the resulting product of step (iv) or step (v) may be pelletized or dusted with a suitable powder before storage.

[0128] In another embodiment, the process for preparing the non-catalyzed (fluoro)silicone rubber substrate forms part of a continuous compounding process. [Example]

[0129] Below are a series of examples:

[0130] In each case, Example 1 and Comparative Examples 1-3 (Comp. 1-3), a series of non-catalyzed fluorosilicone rubber substrates were prepared. In Example 1, the fluorosilicone rubber substrates were prepared according to the process for preparing non-catalyzed (fluoro)silicone rubber substrates described herein using a Colmec™ CTM-65 mixer as a conical screw dump extruder. In accordance with ASTM D-926-08, a dimethylhydroxy-terminated polytrifluoropropylmethylmethylvinylsiloxane rubber having a Williams plasticity of approximately 278 mm / 100 and a vinyl content of 0.188 wt.% was introduced into the Colmec™ CTM-65 mixer in combination with a small amount of a processing aid in the form of 2-5 wt.% vinyl-terminated poly(dimethylsiloxane-co-methylvinylsiloxane) having a viscosity of 370 mPa.s at 12 rpm at 25°C using a Brookfield™ rotational viscometer equipped with a cone-plate apparatus with cone CP-52.

[0131] While the above mixture was being stirred, 40% by weight of untreated fumed silica commercially available from Cabot Corporation as CAB-O-SIL™ MS-75D and approximately 4% by weight of a filler treatment agent comprising a short-chain dimethylhydroxy-terminated polytrifluoropropylmethylsiloxane with an average DP of 5-15 were gradually introduced into a Colmec™ CTM-65 mixer and mixed into the rubber at a speed of approximately 45-60 rpm. After the silica was introduced, mixing was carried out under a nitrogen atmosphere. The compounding ingredients were introduced at approximately 25°C, but the temperature inside the mixer gradually rose to a range of 50-80°C due to the effects of shear mixing. Once the compounding ingredients were thoroughly mixed, the substrate product was held at 150°C for approximately 60 minutes at approximately 15 rpm without a heating step to ensure the removal of volatiles resulting from the in-situ treatment of the filler surface to render it hydrophobic and form a fluorosilicone rubber substrate material.

[0132] The fluorosilicone substrate was then extruded through a Colmec™ CTM-65 mixer and cooled to a temperature below 90°C.

[0133] The resulting fluorosilicone rubber substrate was then mixed with additional fluorosilicone gum in a sigma blade mixer, thereby reducing or trimming the filler content from 40% by weight to 20% by weight. Samples of the resulting substrate containing 20% ​​by weight reinforcing filler were then tested for changes in plasticity over time, with the results shown in Table 1 below. Comparative Examples 1 and 2 were also prepared with only 20% by weight reinforcing filler from the start, and therefore no reduction or trimming step was performed.

[0134] Comparative Example 1 followed the exact same process as described in Example 1, except that the amount of filler introduced into the Colmec™ CTM-65 mixer was 20 wt %, and therefore no reduction or reduction step was necessary.

[0135] In Comparative Example 2, the same ingredients and amounts as in Comparative Example 1 were used to prepare a base material, followed by compounding, but in this example, mixing was carried out using a sigma blade mixer.

[0136] These plasticity properties were then compared with those of Example 1.

[0137] Subsequently, 1.2 parts per hundred (pph) of 2,4-dichlorobenzoyl peroxide was introduced into the uncatalyzed fluorosilicone rubber substrate, which was allowed to cure by milling on a two-roll mill. The resulting cured elastomeric material was evaluated for its cured physical properties. The results are also shown in Table 1 and compared with the cured elastomeric materials of Comparative Examples 1 and 2. Comparative Example 3 was also initiated, and an attempt was made to incorporate 40 wt. % filler into the rubber using a sigma blade mixer. Thus, Comparative Example 3 was an attempt to repeat Example 1 using a sigma blade mixer. However, it was found that such a mixer was not capable of producing a continuous substrate containing 40 wt. % filler. Some of the filler was not incorporated, and the body of the substrate was "brittle" and could not be produced as a satisfactory continuous mass. Therefore, physical property testing for Comparative Example 3 was deemed impossible and it was omitted from Table 1 below.

[0138] [Table 1]

[0139] All plasticity results were measured according to ASTM D-926-08 from the point at which the substrate was freshly milled on a two-roll mill after extrusion from the mixer and after reaching 25°C for Example 1, and from the point at which preparation was completed and freshly milled after reaching 25°C for Comparative Examples 1 and 2. Elongation at break was measured according to ASTM D412, and post-cured samples were post-cured at a temperature of 200°C for 4 hours. Tear strength was measured according to ASTM D624 using Die B.

[0140] The results of Example 1, conducted using a base material prepared as described herein, resulted in lower plasticity than both Comparative Examples 1 and 2, indicating that the base material prepared by the process herein is easier to handle by the user of the base material during compounding. It is also noted that the base material prepared using the conical screw dump extruder shows an improvement over the base material prepared using the sigma blade mixer.

[0141] The plasticity results above appear to be consistent with the physical property results in Table 1, in that the best results were achieved using the process described herein and the worst results were achieved using the sigma blade mixer. It can be seen that Example 1 is a more efficient substrate making process that allows for more filler to be incorporated into the continuous substrate, making the process more efficient compared to the sigma blade process, which requires significantly more energy to mix the filler into the rubber because there is much more rubber.

[0142] A further series of examples and comparative examples (Example 2 and Comparative Examples 4-7) were prepared using dimethylvinyl-terminated polydimethylsiloxane rubber (ie, non-fluorinated).

[0143] In each of Example 2 and Comparative Examples 4-7, a series of non-catalyzed silicone rubber substrates were attempted to be prepared. In Example 2, the silicone rubber substrates were prepared according to the process described herein using a Colmec™ CTM-65 mixer as a conical screw dump extruder. A dimethylvinyl-terminated polydimethylsiloxane rubber having a Williams plasticity of approximately 148 mm / 100 according to ASTM D-926-08 and a vinyl content of 0.012% was introduced into the Colmec™ CTM-65 mixer in combination with a small amount of processing aid in the form of 2-5 wt.% vinyl-terminated poly(dimethylsiloxane-co-methylvinylsiloxane) having a viscosity of 370 mPa.s at 12 rpm at 25°C using a Brookfield™ rotational viscometer equipped with a cone-plate apparatus with cone CP-52.

[0144] While the above mixture was being stirred, 40% by weight of untreated fumed silica commercially available from Cabot Corporation as CAB-O-SIL™ MS-75D and approximately 4% by weight of a filler treatment agent comprising a short-chain dimethylhydroxy-terminated polydimethylsiloxane with an average DP of 5-15 were gradually introduced into a Colmec™ CTM-65 mixer and mixed into the rubber at a speed of approximately 45-60 rpm. Once all of the silica had been introduced, mixing was carried out under a nitrogen atmosphere. The compounding ingredients were introduced at approximately 25°C, but the temperature inside the mixer gradually rose to a range of 50-80°C due to the effects of shear mixing. Once the compounding ingredients were thoroughly mixed, the substrate product was held at 150°C for approximately 60 minutes at approximately 15 rpm without a heating step to ensure the removal of volatiles resulting from the in-situ treatment of the filler surfaces to render them hydrophobic and form a non-catalyzed silicone rubber substrate.

[0145] The silicone rubber substrate was then extruded through a Colmec™ CTM-65 mixer and cooled to a temperature below 90°C.

[0146] The resulting silicone rubber substrate of Example 2 was then mixed with additional dimethylvinyl-terminated polydimethylsiloxane rubber as described above in a sigma blade mixer, into which sufficient dimethylvinyl-terminated polydimethylsiloxane rubber was added with mixing to reduce or eliminate the filler content from 40% to 20% by weight of the substrate. Samples of the resulting substrate containing 20% ​​by weight of reinforcing filler were then tested for change in plasticity over time, with the results shown in Table 2 below.

[0147] Comparative Example 4 followed the exact same process as described in Example 2, except that the amount of filler introduced into the CTM-65 mixer was 20 wt. %, and therefore no reduction or reduction step was necessary. Comparative Example 5 utilized the same formulation ingredients and amounts as Comparative Example 4 to prepare a base material, followed by a compound composition, but in this example, a sigma blade mixer was used for base material preparation. Comparative Examples 6 and 7 were conducted using the same formulation ingredients as Example 2, and attempted to incorporate 40 wt. % filler into the silicone rubber gum using a sigma blade mixer (Comparative Example 6) and a compression-type sigma blade mixer (Comparative Example 7).

[0148] Subsequently, 1.2 parts per hundred (pph) of 2,4-dichlorobenzoyl peroxide was introduced into the uncatalyzed silicone rubber substrate, which was allowed to cure by milling on a two-roll mill, and the resulting compound composition was then cured at 250°F (about 121°C) for 5 minutes. The resulting cured elastomeric material was evaluated for several physical properties. The results are also shown in Table 2 and are compared to the cured elastomers obtained from the preparation of the elastomeric materials of Comparative Examples 4 and 5.

[0149] In the case of Comparative Example 6, as in Comparative Example 3, it was found that the substrate did not continuously agglomerate. It collapsed and did not come back together. Furthermore, when Comparative Example 6 was repeated using a compression-type sigma blade mixer (Comparative Example 7), it was observed that agglomeration could not be achieved when using 40 wt.% filler, even though additional compression using a fixed plate that reduced the free volume in the mixer to <50% of its original volume resulted in a downward compression force on the substrate equal to the upward force from the mixing blade. That is, adding a compression plate to the sigma blade setup did not result in any significant improvement in agglomeration. Therefore, Comparative Examples 6 and 7 could not be reduced (reduced) or hardened, and therefore were not tested for their physical properties.

[0150] The plasticity results for the substrate and the physical property results for the resulting elastomers are set forth below in Table 2 for Example 2 and Comparative Examples 6 and 7.

[0151] [Table 2]

[0152] The test method used was exactly the same as the results in Table 1 above.

[0153] It can be seen that the results of Example 2, conducted using a base material prepared as described herein, resulted in a lower plasticity than both Comparative Examples 4 and 5, indicating that the base material prepared by the process herein is easier to handle by the user of the base material during compounding. It is also noted that the base material prepared using the conical screw dump extruder shows an improvement over the base material prepared using the sigma blade mixer.

[0154] The plasticity results above appear to be consistent with the physical property results in Table 1, in that the best results were achieved using the process described herein and the worst results were achieved using the sigma blade mixer. It can be seen that Example 1 is a more efficient substrate making process that allows for more filler to be incorporated into the continuous substrate, making the process more efficient compared to the sigma blade process, which requires significantly more energy to mix the filler into the rubber due to the much higher amount of rubber present.

[0155] In a further series of examples, the ability to incorporate the non-reinforcing filler aluminum trihydrate into silicone elastomers, often containing non-reinforcing fillers as a flame retardant and smoke suppressant, was evaluated and saturation levels were compared.

[0156] In Example 3, a non-catalyzed substrate was prepared using the exact same process as in Example 2, using a Colmec™ CTM-65 mixer, except that an alternative silicone gum was used. The silicone gum was a vinyldimethyl-terminated polyvinylmethyldimethylsiloxane copolymer with a Williams plasticity of 149.6 mm / 100 and a vinyl content of 0.0654 wt. %. Also in Example 3, a non-catalyzed substrate was prepared without any processing aids in combination with the rubber and without the addition of a catalyst. After a reduction / reduction step to add more gum so that the substrate contained only 20 wt. % reinforcing silica filler, aluminum trihydrate was gradually introduced into the substrate of Example 3 until a saturation level of 170 pph of aluminum trihydrate was added to the substrate (61.5 wt. % of the total composition of gum + reinforcing filler + treating agent + aluminum trihydrate). Two additional comparisons, Comparative Examples 8 and 9, were prepared. In Comparative Example 8, a silicone rubber substrate containing 20 wt. % silica filler was prepared without using a reduction / reduction step. This substrate also had aluminum trihydrate gradually introduced until a saturation level of 150 pph was introduced, after which the substrate began to disintegrate. Therefore, the substrate of Example 3 demonstrates that it can accommodate a greater amount of aluminum trihydrate than Comparative Example 8. Comparative Example 9 was prepared in exactly the same manner as Comparative Example 8, with the only difference being that the substrate containing 20 wt. % silica reinforcing filler was prepared using a sigma blade mixer. In Comparative Example 9, after preparing the substrate containing 20 wt. % silica reinforcing filler, aluminum trihydrate was gradually introduced until a saturation level of 50 pph was introduced, after which the substrate began to disintegrate.

[0157] It can thus be seen that a silicone rubber substrate having a 20 wt. % reinforcing filler content, where the content has been reduced from at least 40 wt. % using a reduction / reduction step using a conical screw dump extruder, can surprisingly accommodate significantly more aluminum trihydrate before reaching saturation than either a substrate containing a 20 wt. % reinforcing filler content prepared without a reduction / reduction step, or in particular a substrate containing a 20 wt. % reinforcing filler content prepared without a reduction / reduction step in a sigma blade mixer.

[0158] In Examples 4 and 5, a base composition was first prepared using 45 wt. % of starting compounding component (b). In Example 4, this was reduced to a base containing 38.5 wt. % reinforcing filler, and in Example 5, this was reduced to a base containing 32 wt. % reinforcing filler. A dimethylvinyl-terminated polydimethylsiloxane rubber having a Williams plasticity of 148 mm / 100 according to ASTM D-926-08 and a vinyl content of 0.012% was combined with a small amount of processing aid in the form of 2-5 wt. % vinyl-terminated poly(dimethylsiloxane-co-methylvinylsiloxane) having a viscosity of 370 mPa.s and introduced into a Colmec™ CTM-65 mixer at 12 rpm at 25°C using a Brookfield™ rotational viscometer equipped with a cone-plate apparatus with cone CP-52.

[0159] While the above mixture was being stirred, 45% by weight of the untreated fumed silica, commercially available from Cabot Corporation as CAB-O-SIL™ MS-75D, and approximately 4% by weight of a filler treatment comprising a short-chain dimethylhydroxy-terminated polydimethylsiloxane with an average DP of 5-15 were gradually introduced into a Colmec™ CTM-65 mixer and mixed into the rubber at a speed of approximately 45-60 rpm. Once all of the silica was introduced, mixing was carried out under a nitrogen atmosphere. The compounding ingredients were introduced at approximately 25°C, but the temperature inside the mixer gradually rose to a range of 50-80°C due to the effects of shear mixing. Once the compounding ingredients were thoroughly mixed, the substrate product was held at 150°C for approximately 60 minutes at approximately 15 rpm without a heating step to ensure the removal of volatiles resulting from the in-situ treatment of the filler surfaces to render them hydrophobic and form a non-catalyzed silicone rubber substrate.

[0160] The silicone rubber substrate was then cooled to below 60°C in a Colmec™ CTM-65 mixer before being extruded therefrom. In this case, the extruded silicone rubber substrate was actually returned to the Colmec™ CTM-65 mixer for step (v) to undergo reduction / reduction. In Example 4, sufficient dimethylvinyl-terminated polydimethylsiloxane rubber having a Williams plasticity of 148 mm / 100 and a vinyl content of 0.012% according to ASTM D-926-08 was introduced into the Colmec™ CTM-65 mixer to provide a final substrate product containing a total of 38.5 wt% reinforcing filler after step (v).

[0161] In Example 5, the exact same process was followed except that more rubber was introduced in step (v) to give a final substrate product containing a total of 32.0 wt. % reinforcing filler.

[0162] In each of Examples 4 and 5, compounds were made according to step (vi) herein, and each resulting sample was prepared by introducing 1.2 parts per hundred (pph) of 2,4-dichlorobenzoyl peroxide into a non-catalyzed silicone rubber substrate and allowing it to cure by milling on a two-roll mill, and then curing the resulting compound composition at 250°F (about 121°C) for 5 minutes. In this case, some samples of both Examples 4 and 5 were cured at a temperature of 200°C for 4 hours. Post-cured.

[0163] The physical properties of the resulting cured silicone elastomer were evaluated, and the results are shown in Table 3 below. A sample of the original substrate (Reference 1) with 45 wt. % reinforcing filler with peroxide catalyst milled in the same manner was also evaluated for its physical properties, using the same test methods as described above.

[0164] [Table 3]

[0165] These results demonstrate that it is possible to prepare high viscosity base stocks incorporating high levels of silica filler, and then reduce or eliminate the filler content to other, lower filler loadings, successfully producing base stocks with an acceptable range of properties at each loading.

Claims

1. 1. A process for the preparation of a non-catalyzed (fluoro)silicone rubber substrate prepared by incorporating a reinforcing filler and optionally a hydrophobizing treatment agent into one or more silicone polymers, fluorosilicone polymers or copolymers thereof, in each case said one or more silicone polymers, fluorosilicone polymers or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, the process comprising the following steps: (i) introducing, as a first starting compounding component, the one or more silicone polymers, fluorosilicone polymers or copolymers thereof, in each case having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, into the mixing chamber of a mixer at about 25°C, optionally in an inert atmosphere, and mixing; (ii) gradually introducing one or more reinforcing fillers, as a second starting formulation component, and optionally a third starting formulation component, one or more hydrophobizing filler treating agents, into the mixing chamber of the mixer while continuing mixing until the mixer is charged with a predetermined amount of reinforcing fillers, that is at least 38% by weight of the total base starting formulation components, to form a base mixture; (iii) optionally maintaining the temperature of the substrate mixture in the mixing chamber within a predetermined range of 100-200°C for up to 6 hours to remove volatiles from the substrate mixture of step (ii) to form a substrate mixture of step (iii), which, if utilized, may be performed under vacuum; (iv) cooling the obtained base mixture of step (ii) or base mixture of step (iii) to a temperature of 25°C to 120°C before, during or after step (iv); (v) reducing the weight percent of reinforcing filler in said base mixture of step (ii) or step (iii) to a predetermined amount by blending said base mixture of step (ii) or step (iii) with additional one or more silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 to form a non-catalyzed (fluoro)silicone rubber substrate; The mixer utilized for at least steps (i), (ii) and (iii) is a conical screw dump extruder comprising a conical twin screw mixing chamber containing two counter-rotating conical screws converging towards an extrusion die having an inlet and an outlet, the flow path through the extrusion die being controlled by an obstruction means whereby the outlet of the extrusion die is such that the product of steps (iii), (iv) or (v) exits the conical screw dump extruder if or when the uncatalyzed (fluoro)silicone rubber substrate is further processed or stored outside the conical screw dump extruder. and adapted to be closed by said closing means until extruded from a crew dump extruder, and adapted to be opened after step (iii), (iv) or (v), wherein during mixing, the substrate mixture is driven towards an extrusion die by a pair of counter-rotating conical screws, and then the extrusion die is closed by said closing means and then forced back when opened after step (iii), (iv) or (v), to allow the product of step (iii), (iv) or (v) to be extruded through the extrusion die for further processing and / or storage.

2. 10. The process of claim 1, wherein the base mixture of step (ii) and the product of step (iv) contain 39 to 55 weight percent reinforcing filler.

3. 3. The process of claim 1 or 2, wherein the silicone polymer, fluorosilicone polymer, or copolymer thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 in each case is selected from dialkylalkenyl-terminated polydimethylsiloxane, dialkylalkenyl-terminated dimethylmethylphenylsiloxane, trialkyl-terminated dimethylmethylvinylpolysiloxane, dialkylvinyl-terminated dimethylmethylvinylpolysiloxane copolymer, dialkylvinyl-terminated methylphenylpolysiloxane, dialkylalkenyl-terminated methylvinylmethylphenylsiloxane, dialkylalkenyl-terminated methylvinyldiphenylsiloxane, dialkylalkenyl-terminated methylvinylmethylphenyldimethylsiloxane, trimethyl-terminated methylvinylmethylphenylsiloxane, trimethyl-terminated methylvinyldiphenylsiloxane, or trimethyl-terminated methylvinylmethylphenyldimethylsiloxane.

4. In each case, said silicone polymer, fluorosilicone polymer or copolymer thereof having a Williams plasticity number of at least 100 mm / 100 according to ASTM D-926-08 is trimethyl-terminated polymethyltrifluoropropylsiloxane, 3. The process of claim 1 or 2, wherein the siloxane is selected from dimethylalkenyl-terminated polymethyltrifluoropropylsiloxane, dimethylsilanol-terminated polymethyltrifluoropropylsiloxane, trimethyl-terminated polymethylperfluoropropylsiloxane, dimethylalkenyl-terminated polymethylperfluoropropylsiloxane, or dimethylsilanol-terminated polymethyltrifluoropropylsiloxane.

5. 5. The process of any one of claims 1 to 4, wherein the additional one or more silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity according to ASTM D-926-08 of at least 100 mm / 100 added in step (v) can be the same as or different from that introduced in step (i).

6. The process of any one of claims 1 to 5, wherein the process comprises step (v).

7. 7. The process of any one of claims 1 to 6, wherein a silicone polymer, fluorosilicone polymer or copolymer thereof having a Williams plasticity of less than 100 mm / 100 and / or a silicone polymer, fluorosilicone polymer or copolymer having a viscosity of from 10,000 MPa.s at 25°C to 500,000 MPa.s at 25°C is introduced during step (i) and / or step (v) of the process in a cumulative total of up to 10% by weight of the total base starting formulation components.

8. 8. The process of any one of claims 1 to 7, wherein in step (v), the weight percent of reinforcing filler in the uncatalyzed (fluoro)silicone rubber substrate is reduced to an amount of 15 wt% to 30 wt%, based on the weight percent of the total substrate starting compounding ingredients, by blending the product of step (iv) with additional one or more silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 to form the step (v) product.

9. The cooling step (iv) of the (fluoro)silicone rubber substrate production process comprises: (I) entirely in the conical screw dump extruder used to make the non-catalyzed (fluoro)silicone rubber substrate, in which case the resulting non-catalyzed (fluoro)silicone rubber substrate is extruded at low temperatures, in the range of 30-40°C; or (II) partially in the conical screw dump extruder used to make the non-catalyzed (fluoro)silicone rubber substrate, where the resulting non-catalyzed (fluoro)silicone rubber substrate is extruded at moderate temperatures in the range of 50-80°C and then transferred to an alternative means for further cooling; or (III) The process of any one of claims 1 to 8, which is carried out entirely outside of the conical screw dump extruder used to make the non-catalyzed (fluoro)silicone rubber substrate, in which case the resulting non-catalyzed (fluoro)silicone rubber substrate is "hot" extruded at a temperature of 80°C to 120°C, alternatively at a temperature of 90°C to 120°C, and then transferred to an alternative means for cooling.

10. 10. The process of claim 9, wherein cooling outside the conical screw dump extruder is performed in a second "cooled" conical screw dump extruder, pan, or other container, allowing the conical screw dump extruder used to make the non-catalyzed (fluoro)silicone rubber substrate to be reused to make additional batches of non-catalyzed (fluoro)silicone rubber substrate.

11. 10. The process according to any one of claims 1 to 9, wherein after step (iv) or (v), the obtained product of step (iv) or step (v) is pelletized or dusted with a suitable powder before storage.

12. A process according to any one of claims 1 to 10, wherein said process for the preparation of non-catalysed (fluoro)silicone rubber substrates forms part of a continuous compounding process.

13. 7. The process of claim 6, wherein there is an additional step (vi) occurring simultaneously with or subsequent to step (v), said step (v) being after step (iv), said step (vi) comprising introducing at a temperature between 25°C and 60°C at least one catalyst or vulcanizing agent, and optionally one or more additives selected from crosslinking agents, cure inhibitors, additional fillers, pigments, property modifiers, and the like.

14. An uncatalyzed (fluoro)silicone rubber substrate which is the product of the process of any one of claims 1 to 10 and / or a catalyzed (fluoro)silicone rubber substrate which is the product of the process of claim 11.

15. A non-catalyzed (fluoro)silicone rubber substrate obtained or obtainable by the process according to any one of claims 1 to 10.

16. 1. Use of a conical screw dump extruder comprising a conical twin-screw mixing chamber housing two counter-rotating conical screws converging towards an extrusion die having an inlet and an outlet, in a process for the preparation of a non-catalyzed (fluoro)silicone rubber substrate prepared by introducing a reinforcing filler and optionally a hydrophobic treatment agent into one or more silicone polymers, fluorosilicone polymers or copolymers thereof, wherein the flow path through the extrusion die is controlled by an obstruction means, whereby the outlet of the extrusion die is adapted to be closed by the obstruction means, and in each case the one or more silicone polymers, fluorosilicone polymers or copolymers thereof have a Williams plasticity number of at least 100 mm / 100 according to ASTM D-926-08, and the process comprises the following steps: (i) introducing, as a first starting compounding component, the one or more silicone polymers, fluorosilicone polymers or copolymers thereof, in each case having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, into the mixing chamber of a mixer at about 25°C, optionally in an inert atmosphere, and mixing; (ii) gradually introducing one or more reinforcing fillers, as a second starting formulation component, and optionally a third starting formulation component, one or more hydrophobizing filler treating agents, into the mixing chamber of the mixer while continuing mixing until the mixer is charged with a predetermined amount of reinforcing fillers, that is at least 38% by weight of the total base starting formulation components, to form a base mixture; (iii) optionally maintaining the temperature of the substrate mixture in the mixing chamber within a predetermined range of 100-200°C for up to 6 hours to remove volatiles from the substrate mixture of step (ii) to form a substrate mixture of step (iii), which, if utilized, may be performed under vacuum; (iv) cooling the obtained base mixture of step (ii) or base mixture of step (iii) to a temperature of 25°C to 120°C before, during or after step (iv); (v) reducing the weight percent of reinforcing filler in said base mixture of step (ii) or step (iii) to a predetermined amount by blending said base mixture of step (ii) or step (iii) with additional one or more silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 to form a non-catalyzed (fluoro)silicone rubber substrate; Use wherein during mixing, the substrate mixture is driven towards an extrusion die by a pair of counter-rotating conical screws, and then the extrusion die is closed by a closure means and then forced back when opened after said steps (iii), (iv) or (v), allowing the product of said steps (iii), (iv) or (v), respectively, to be extruded through said extrusion die for further processing and / or storage.

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