Silicone production

Abstract

The present invention relates to an improved process for the preparation of an uncatalyzed (fluoro) silicone rubber matrix by introducing a reinforcing filler into a high viscosity (i.e., greater than 1,000 at 25 DEG C, greater than 1,000,000 at 25 DEG C, greater than 1,000,000 at 25 DEG C) in the presence of a filler treatment agent optionally used in situ to render the filler hydrophobic. The present invention relates to a high viscosity (i.e., greater than 1,000,000 mPa.s) silicone polymer and / or a high viscosity (i.e., greater than 1,000,000 mPa.s at 25 DEG C) fluorinated silicone polymer (commonly referred to in the industry as silicone polymer gum and fluorinated silicone polymer gum, respectively) and their copolymers. The uncatalyzed silicone rubber matrix is then further mixed with one or more catalysts / vulcanizing agents and, when desired, a crosslinker and optionally various additives to form a curable one-component or multi-component silicone rubber compound composition. The invention also relates to silicone elastomers made by curing said curable one-component or multi-component silicone rubber compound composition.

Description

[0001] The present invention relates to an improved method for preparing an uncatalyzed (fluorinated) organosilicon rubber matrix, which is prepared by introducing reinforcing fillers into high-viscosity (i.e., greater than 1,000,000 mPa·s at 25 °C) organosilicon polymers and / or high-viscosity (i.e., greater than 1,000,000 mPa·s at 25 °C) fluorinated organosilicon polymers (commonly referred to as organosilicon polymer gums and fluorinated organosilicon polymer gums, respectively, in the industry) and their copolymers, optionally in the presence of a filler treatment agent used in situ to render the fillers hydrophobic. The uncatalyzed organosilicon rubber matrix is then further mixed with one or more catalysts / vulcanizing agents and, when required, crosslinking agents and optional various additives to form a curable one-component or multi-component organosilicon rubber compound composition. The present invention also relates to an organosilicon elastomer made by curing the curable one-component or multi-component organosilicon rubber compound composition.

[0002] High-viscosity organosilicon polymers, high-viscosity fluorinated organosilicon polymers, and their copolymers can be prepared by the polymerization of organocyclosiloxane oligomers, which typically contain 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, cyclopent(methylvinyl)siloxane, cyclotris(methylvinyl)siloxane, and cyclotetrakis(methylvinyl)siloxane, cyclotetrakis(phenylmethyl)siloxane, cyclopentylmethylhydrogensiloxane, trifluoropropylmethylcyclotrisiloxane, and mixtures thereof.

[0003] Typically, organocyclosiloxane oligomers and their mixtures (alone or together with appropriately capped polydiorganosiloxanes) undergo a polymerization process involving the ring-opening of organocyclosiloxane oligomers in the presence of a catalyst such as an acid or a base. During the polymerization reaction, an equilibrium is established between the desired high-molecular-weight compound and the mixture of organocyclosiloxane compounds. The resulting equilibrium mainly depends on the nature and quantity of the organocyclosiloxane compounds, the catalyst used, and the polymerization method temperature. This polymerization method is typically carried out in the absence of a solvent. Typically, capping agents are used to increase functionality and regulate the molecular weight of the resulting polymer.

[0004] For example, organosilicon polymers and copolymers containing fluoroalkyl groups (such as trifluoropropyl groups) or perfluoroalkyl groups can be, for example:

[0005] R 1 (R 2 ) 2SiO-((R 4 )(R 3 )SiO) m -Si(R 1 )(R 2 )(I)

[0006] R 1 (R 2 ) 2 SiO-((R 4 )(R 3 )SiO) m -((R 2 ) 2 SiO) q Si(R 1 )(R 2 ) 2 (II)

[0007] wherein

[0008] each R 2 is the same or different and is a saturated monovalent hydrocarbon radical group such as an alkyl group, an aryl group or an alkaryl group, a fluoroalkyl group or a perfluoroalkyl group;

[0009] each R 1 is -OH, hydrogen, an alkenyl group or an alkynyl group;

[0010] each R 3 is a fluoroalkyl group or a perfluoroalkyl group;

[0011] each R 4 is R 2 or an unsaturated monovalent hydrocarbon radical group such as an alkenyl group or an alkynyl group; and q and m are positive integers. The copolymer can be a random or block copolymer.

[0012] The resulting silicone polymer gum and fluorosilicone polymer gum and their copolymers (collectively referred to hereinafter as (fluoro)silicone gum) are used to prepare the uncatalyzed matrix of the (fluoro)silicone gum (collectively referred to hereinafter as (fluoro)silicone matrix), and these uncatalyzed matrices are subsequently modified with a catalyst and optional additives in the preparation of a catalytic, curable one-component or multi-component silicone rubber compound composition (commonly referred to as "high-consistency" silicone rubber (HCR) or fluorosilicone rubber (FSR) compound composition (hereinafter referred to as "(fluoro)silicone rubber compound composition")), which provides an elastomer with excellent mechanical and electrical insulation properties upon curing / vulcanization.

[0013] (Fluorinated) organosilicon rubber matrices are typically prepared in a first production stage (sometimes referred to as the "hot mixing" stage), during which reinforcing fillers are introduced into the (fluorinated) organosilicone rubber. Unless the reinforcing fillers have been pretreated, filler treatment agents are also used in situ to render the outer surfaces of the fillers hydrophobic. One or more optional "non-curing" additives, such as extender fillers (sometimes referred to as non-reinforcing fillers) or vinyl processing aids, may be introduced in this first stage, provided that they do not include any catalyst / vulcanizing agent. This results in the preparation of an uncatalyzed (fluorinated) organosilicon rubber matrix, which can be stored and packaged for sale or future use, or can be used in a second stage, sometimes referred to as the cold mixing stage or compounding stage.

[0014] The second stage, sometimes referred to as the cold mixing stage, involves introducing into the uncatalyzed (fluorinated) organosilicon rubber matrix produced in the first stage at least one of the following: a catalyst / vulcanizing agent and a crosslinking agent (if required in the latter case) and other additives, such as a cure inhibitor, additional fillers, pigments, property modifiers, etc. The ingredients and additives to be introduced during the second stage are thoroughly mixed into the matrix to ensure uniform distribution in the resulting (fluorinated) organosilicon rubber compound composition. If desired, in cases where the compound composition is to be hydrosilylated (addition) cured, the uncatalyzed (fluorinated) organosilicon rubber matrix can be separated such that different additives are introduced into different portions, typically for example into two portions (portion A and portion B), where portion A contains the catalyst and portion B contains the crosslinking agent. The two portions are mixed together prior to curing.

[0015] The hot mixing used in the manufacture of the (fluorinated) organosilicon rubber matrix can include, for example, metering the filler into the (fluorinated) organosilicone rubber to ensure that the filler is well dispersed therein and is properly hydrophobically treated. It also includes the removal of volatiles and must be cooled at the end of mixing to enable safe transfer and, if desired, packaging.

[0016] Thus, it is a time-consuming, energy-intensive and expensive process. This is even more the case for the hot mixing stage than for the compounding or cold stage used to introduce the catalyst and other curing agents and other additional additives to prepare the compound composition. For example, one problem is that, given the nature of the (fluorinated) organosilicone rubber and the historical mixer technology available to the manufacturer (e.g., sigma blade mixers), the production of an uncatalyzed (fluorinated) organosilicon rubber matrix is only possible in the presence of the reinforcing filler in an amount up to a maximum of about 35 wt% of the matrix.

[0017] Thus, there has been a long-term desire in the industry to increase efficiency and reduce the necessary time required for thermal mixing used in the manufacture of the (fluorinated) organosilicon rubber matrix per kilogram of finished compound composition, as it potentially can provide significant economic benefits by increasing productivity in the most costly and technically complex matrix manufacturing methods.

[0018] Provided herein is a method for preparing an uncatalyzed (fluorinated) organosilicon rubber matrix, the uncatalyzed (fluorinated) organosilicon rubber matrix being prepared by introducing reinforcing fillers and optionally a hydrophobic treatment agent into one or more organosilicon polymers, fluorinated organosilicon polymers, or copolymers thereof, where in each case the one or more organosilicon polymers, fluorinated organosilicon polymers, or copolymers thereof have a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, the method comprising the steps of:

[0019] (i) introducing the one or more organosilicon polymers, fluorinated organosilicon polymers, or copolymers thereof, as a first starting component, into the mixing chamber of a mixer at about 25 °C, optionally in an inert atmosphere, and mixing, where in each case the one or more organosilicon polymers, fluorinated organosilicon polymers, or copolymers thereof have a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08;

[0020] (ii) gradually introducing one or more reinforcing fillers, as a second starting component, and optionally a third starting component, one or more hydrophobic filler treatment agents, into the mixing chamber of the mixer while continuing to mix until the mixer has been charged with a predetermined amount of reinforcing fillers of at least 38 wt% of the total basic starting components to form a basic mixture;

[0021] (iii) optionally maintaining the temperature of the basic mixture in the mixing chamber within a predetermined range of 100 °C to 200 °C for a period of up to 6 hours to remove volatiles from the basic mixture of step (ii), thereby forming a basic mixture of step (iii), where step (iii) can be carried out under vacuum when in use;

[0022] (iv) cooling the resulting basic mixture of step (ii) or step (iii) to a temperature of 25 °C to 120 °C; and before, during, or after step (iv)

[0023] (v) Reducing the weight percentage of the reinforcing filler in the base mixture of step (ii) or step (iii) to a predetermined amount by mixing the base mixture of step (ii) or 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 an uncatalyzed (fluoro)silicone rubber matrix;

[0024] Reducing the weight percentage of the reinforcing filler in the base mixture of step (ii) or step (iii) to a predetermined amount to form an uncatalyzed (fluoro)silicone rubber matrix;

[0025] Characterized in that at least the mixer for steps (i), (ii), and (iii) is a conical screw extruder comprising a conical twin-screw mixing chamber that houses two counter-rotating conical screws that converge towards an extrusion die head having an inlet and an outlet, wherein the passage through the extrusion die head is controlled by a shut-off device such that the outlet of the extrusion die head is adapted to be closed by the shut-off device until the product of step (iii), (iv), or (v) is to be extruded from the conical screw extruder and is opened after step (iii), (iv), or (v) if or when the uncatalyzed (fluoro)silicone rubber matrix is to be further processed or stored outside the conical screw extruder, such that during mixing, the base mixture is driven towards the extrusion die head by a pair of counter-rotating conical screws and then forced to return when the extrusion die head is closed by the shut-off device and is then opened after step (iii), (iv), or (v) to allow the product of step (iii), (iv), or (v) to be extruded through the extrusion die head for further processing and / or storage.

[0026] An uncatalyzed (fluoro)silicone rubber matrix as a product of the above method is also provided.

[0027] An uncatalyzed (fluoro)silicone rubber matrix obtainable by or capable of being obtained by the above method is also provided.

[0028] The use of a conical screw tablet press is also provided, the conical screw tablet press comprising a conical twin-screw mixing chamber that houses two counter-rotating conical screws that converge towards an extrusion die head having an inlet and an outlet, wherein the passage through the extrusion die head is controlled by a blocking device such that the outlet of the extrusion die head is adapted to be closed by the blocking device in a process for preparing an uncatalyzed (fluoro)organosiloxane rubber matrix, the uncatalyzed (fluoro)organosiloxane rubber matrix being prepared by introducing reinforcing fillers and optionally a hydrophobic treatment agent into one or more organosiloxane polymers, fluoroorganosiloxane polymers, or copolymers thereof, in each case the one or more organosiloxane polymers, fluoroorganosiloxane 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:

[0029] (i) introducing the one or more organosiloxane polymers, fluoroorganosiloxane polymers, or copolymers thereof as a first starting component into the mixing chamber of a mixer at about 25 °C, optionally in an inert atmosphere, and mixing, the one or more organosiloxane polymers, fluoroorganosiloxane polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 in each case according to ASTM D-926-08;

[0030] (ii) gradually introducing one or more reinforcing fillers as a second starting component and optionally a third starting component, one or more hydrophobic filler treatment agents, into the mixing chamber of the mixer while continuing to mix until the mixer has been charged with a predetermined amount of reinforcing filler of at least 38 wt% of the total basic starting components to form a basic mixture;

[0031] (iii) optionally maintaining the temperature of the basic mixture in the mixing chamber within a predetermined range of 100 °C to 200 °C for a period of up to 6 hours to remove volatiles from the basic mixture of step (ii) to form a basic mixture of step (iii), the step (iii) being capable of being carried out under vacuum when in use;

[0032] (iv) cooling the resulting basic mixture of step (ii) or step (iii) to a temperature of 25 °C

[0033] to 120 °C; and before, during, or after step (iv);

[0034] (v) Reducing the weight % of the reinforcing filler in the step (ii) base mixture or step (iii) base mixture to a predetermined amount by mixing the step (ii) base mixture or step (iii) base mixture 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 an uncatalyzed (fluoro)silicone rubber matrix;

[0035] Wherein during mixing, the base mixture is driven towards an extrusion die head by a pair of counter-rotating conical screws, then forced to return when the extrusion die head is closed by the plugging device, and then opened after step (iii), (iv), or (v) to allow the product of step (iii), (iv), or (v) to be extruded through the extrusion die head for further processing and / or storage.

[0036] Provided herein is a method for preparing a catalyzed (fluoro)silicone rubber compound composition, the catalyzed (fluoro)silicone rubber compound composition being prepared by introducing a reinforcing filler and an optional hydrophobic 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 method comprising the following steps:

[0037] (i) Introducing and mixing the one or more silicone polymers, fluorosilicone polymers, or copolymers thereof as a first starting component into a mixing chamber of a mixer at about 25 °C, optionally in an inert atmosphere, the one or more silicone polymers, fluorosilicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 in each case according to ASTM D-926-08;

[0038] (ii) Gradually introducing one or more reinforcing fillers as a second starting component and an optional third starting component, one or more hydrophobic filler treatment agents into the mixing chamber of the mixer while continuing to mix until the mixer has been charged with a predetermined amount of reinforcing filler of at least 38 wt% of the total base starting components to form a base mixture;

[0039] (iii) Optionally maintaining the temperature of the base mixture in the mixing chamber within a predetermined range of 100 °C to 200 °C for a period of up to 6 hours to remove volatiles from the step (ii) base mixture, thereby forming a step (iii) base mixture, the step (iii) being capable of being carried out under vacuum when in use;

[0040] (iv) Cool the resulting base mixture of step (ii) or step (iii) to a temperature of 25 °C

[0041] to 120 °C; and before, during or after step (iv);

[0042] (v) Reduce the weight % of the reinforcing filler in the base mixture of step (ii) or step (iii) to a predetermined amount by mixing the base mixture of step (ii) or 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 an uncatalyzed (fluoro)silicone rubber matrix;

[0043] (vi) At a temperature of 25 °C to 60 °C, introduce at least one catalyst or vulcanizing agent and optionally one or more additives selected from crosslinking agents, curing inhibitors, additional fillers, pigments, property modifiers, etc.;

[0044] It is characterized in that at least the mixer for steps (i), (ii) and (iii) is a conical screw press including a conical twin - screw mixing chamber that houses two counter - rotating conical screws that converge towards an extrusion die head having an inlet and an outlet, wherein the passage through the extrusion die head is controlled by a blocking device such that the outlet of the extrusion die head is adapted to be closed by the blocking device until the product of step (iii), (iv) or (v) is to be extruded from the conical screw press and is opened after step (iii), (iv) or (v) if or when the uncatalyzed (fluoro)silicone rubber matrix is to be further processed or stored outside the conical screw press, so that during mixing, the base mixture is driven towards the extrusion die head by a pair of counter - rotating conical screws and then forced to return when the extrusion die head is closed by the blocking device and then opened after step (iii), (iv) or (v) to allow the product of step (iii), (iv) or (v) to be extruded through the extrusion die head for further processing and / or storage; and wherein step (vi) is carried out simultaneously with step (v) or after step (v).

[0045] There is also provided a catalyzed (fluoro)silicone rubber compound composition as a product of the above - mentioned method.

[0046] There is also provided a catalyzed (fluoro)silicone rubber compound composition obtainable or obtained by the above - mentioned method.

[0047] Also provided is the use of a conical screw tablet press, which comprises a conical twin-screw mixing chamber that houses two counter-rotating conical screws converging towards an extrusion die head having an inlet and an outlet, wherein the passage through the extrusion die head is controlled by a shut-off device such that the outlet of the extrusion die head is adapted to be closed by the shut-off device in a process for preparing an uncatalyzed (fluoro)organosiloxane rubber matrix, the uncatalyzed (fluoro)organosiloxane rubber matrix being prepared by introducing reinforcing fillers and optionally a hydrophobic treatment agent into one or more organosiloxane polymers, fluoroorganosiloxane polymers or copolymers thereof, in each case the one or more organosiloxane polymers, fluoroorganosiloxane polymers or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, the method comprising the following steps:

[0048] (i) introducing the one or more organosiloxane polymers, fluoroorganosiloxane polymers or copolymers thereof, as a first starting component, into the mixing chamber of a mixer at about 25 °C, optionally in an inert atmosphere, and mixing, the one or more organosiloxane polymers, fluoroorganosiloxane polymers or copolymers thereof having a Williams plasticity of at least 100 mm / 100 in each case according to ASTM D-926-08;

[0049] (ii) gradually introducing one or more reinforcing fillers, as a second starting component, and optionally a third starting component, one or more hydrophobic filler treatment agents, into the mixing chamber of the mixer while continuing to mix until the mixer has been charged with a predetermined amount of reinforcing fillers of at least 38% by weight of the total basic starting components to form a basic mixture;

[0050] (iii) optionally maintaining the temperature of the basic mixture in the mixing chamber within a predetermined range of 100 °C to 200 °C for a period of up to 6 hours to remove volatiles from the basic mixture of step (ii) to form a basic mixture of step (iii), the step (iii) being capable of being carried out under vacuum when in use;

[0051] (iv) cooling the resulting basic mixture of step (ii) or step (iii) to a temperature of 25 °C

[0052] to 120 °C; and before, during or after step (iv);

[0053] (v) Reducing the weight percentage of the reinforcing filler in the step (ii) base mixture or step (iii) base mixture to a predetermined amount by mixing the step (ii) base mixture or step (iii) base mixture 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 an uncatalyzed (fluoro)silicone rubber matrix;

[0054] (vi) Introducing at least one catalyst or vulcanizing agent and optionally one or more additives at a temperature of 25 °C to 60 °C, the one or more additives being selected from crosslinking agents, curing inhibitors, additional fillers, pigments, property modifiers, etc.;

[0055] Wherein during mixing, the base mixture is driven towards an extrusion die head by a pair of counter-rotating conical screws, then forced to return when the extrusion die head is closed by the blocking device, and then opened after step (iii), (iv), or (v) to allow the product of step (iii), (iv), or (v) to be extruded through the extrusion die head for further processing and / or storage; and wherein step (vi) is carried out simultaneously with step (v) or after step (v).

[0056] It should be understood that the present disclosure relates to a method for preparing an uncatalyzed (fluoro)silicone rubber matrix, which can then be used to prepare a curable compound composition by adding a catalyst, crosslinking agent, etc. to the matrix. It does not relate to a polymerization method for preparing a silicone polymer, fluorosilicone polymer, or copolymer thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, which is one of the starting components in the method described herein.

[0057] The uncatalyzed (fluoro)silicone rubber matrix is intended to represent 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 any curing agent and / or crosslinking agent, i.e., it is uncatalyzed, and thus such a mixture cannot be cured into an elastomer, etc. until it is converted into a curable compound composition containing a curing agent and / or crosslinking agent (if required) and other additives.

[0058] Reinforcing fillers are incorporated into silicone rubber materials to enhance the strength and toughness of the cured elastomeric materials. The reinforcing fillers are highly surface active and have a high surface area, which enhance the cured siloxane polymer matrix by hydrogen bonding and other means. Incremental fillers (sometimes referred to as non-reinforcing fillers) typically have a lower surface area and are mainly used to reduce the cost of silicone rubber. The reinforcing fillers generally achieve at least one of the following mechanical properties, thereby enhancing excellent tensile strength, tear strength, and flex fatigue resistance, increasing reduced wrinkle hardening, improving compression set resistance, and can provide, for example, excellent heat aging resistance for the silicone elastomer.

[0059] It has surprisingly been found that using a conical screw kneader instead of the usual historical mixers (such as sigma blade mixers) allows an increase in the amount of reinforcing filler that can be introduced into the uncatalyzed (fluorinated) silicone rubber matrix by several weight percent before saturation (at which point the matrix will break and no longer be continuous). This increase is significant as it improves the efficiency of matrix manufacturing, i.e., productivity, by reducing the hot mixing time per kg of finished matrix, resulting in corresponding economic benefits and an increase in the productivity of the hot mixer. This increase in productivity is achieved by the ability to manufacture uncatalyzed (fluorinated) silicone rubber matrix products that are more highly filled than can be manufactured using current mixing techniques (such as sigma blade mixers, where the absolute maximum filler incorporation level does not seem to exceed 35 wt% of the matrix). This increase in filler loading also results in a higher plasticity material at higher shear rates during mixing. This higher shear is thought to lead to improved dispersion of the filler, which seems to reduce the Williams plasticity of the resulting matrix material and can increase the transparency of the cured product incorporated into such a matrix material.

[0060] Furthermore, when using the conical screw kneader, the filler content of the resulting matrix is usually reduced or trimmed to a predetermined concentration of a less filled matrix using additional silicone polymers, fluorinated silicone polymers, or copolymers thereof. These can be silicone polymers, fluorinated silicone polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, but alternatively include shorter chain silicone polymers, fluorinated silicone polymers, or copolymers thereof if desired. It has been found that such matrices reduced or trimmed to a predetermined concentration have a lower Williams plasticity and are thus easier to use during compounding, and in fact, elastomeric materials prepared from compound compositions using such matrices provide improved mechanical properties compared to elastomeric materials prepared using standard mixers (such as sigma blade mixers).

[0061] The uncatalyzed (fluorinated) silicone rubber matrix prepared by the method herein contains two basic starting components:

[0062] (a) A silicone polymer, fluorosilicone polymer, or copolymer thereof, i.e., a (fluoro)organosilicate, having a Williams plasticity of at least 100 mm / 100 in each case according to ASTM D - 926 - 08, and

[0063] (b) a reinforcing filler.

[0064] When the reinforcing filler has been pretreated, other components are not necessary, and the matrix is prepared by mixing the two with any desired optional non - curing additives. Economically, using such pretreated fillers can greatly increase the cost of preparing an uncatalyzed (fluoro)silicone rubber matrix. Therefore, especially for economic reasons, this is not preferred in the vast majority of cases.

[0065] Therefore, the reinforcing filler is usually introduced into the mixer in an untreated form and its outer surface is made hydrophobic by an in - situ treatment method during matrix preparation. In this case, a third component, a suitable treating agent (c) that makes the filler hydrophobic, is required to produce an uncatalyzed (fluoro)silicone rubber matrix.

[0066] Starting ingredient / component (a)

[0067] The starting component (a) is an organopolysiloxane polymer having a Williams plasticity of at least 100 mm / 100 as measured according to ASTM D - 926 - 08. Since it is difficult to measure the viscosity of highly viscous fluids, (fluoro)organosilicates tend to be defined by their Williams plasticity (the ability of a specimen to undergo compressive deformation under an external force and retain the deformation after the external force is removed) rather than by viscosity. Usually, in the case of a fluorosilicone polymer gum measured according to ASTM D - 926 - 08, the Williams plasticity value of the silicone polymer gum can be at most about 400 mm / 100.

[0068] Each organopolysiloxane polymer of component (a) contains a plurality of siloxy units of formula (I):

[0069] R’ a SiO (4-a) / 2 (I)

[0070] The subscript “a” is 0, 1, 2, or 3.

[0071] The siloxy units can be described by shorthand (abbreviated) nomenclature, i.e., - “M”, “D”, “T”, and “Q”. At this time, each R' is any suitable group, usually an organic group, such as an alkyl group. The M unit corresponds to the siloxy unit where a = 3, i.e., R’ 3 SiO 1 / 2; The D unit corresponds to a siloxy unit, where a = 2, i.e., R' 2 SiO 2 / 2 ; The T unit corresponds to a siloxy unit, where a = 1, i.e., R' 1 SiO 3 / 2 ; The Q unit corresponds to a siloxy unit, where a = 0, i.e., SiO 4 / 2 .

[0072] The organopolysiloxane polymer of component (a) is generally linear or substantially linear, which means that due to the presence of T units (as described above) in the molecule, it contains less than 2.5 wt%, alternatively less than 1.5 wt%, alternatively less than 0.5 wt%, alternatively less than 0.1 wt% of branching, and thus the average value of a in structure (I) is about 2.

[0073] Each organic group R' in the above formula (I) is independently selected from aliphatic hydrocarbon groups, substituted aliphatic hydrocarbon groups, aromatic groups or substituted aromatic groups. Each aliphatic hydrocarbon group can be exemplified by, but not limited to, the following: alkyl groups or cycloalkyl groups having 1 to 20 carbons / group, alternatively 1 to 15 carbons / group, alternatively 1 to 12 carbons / group, alternatively 1 to 10 carbons / group, alternatively 1 to 6 carbons / group, such as cyclohexyl. Specific examples of alkyl groups can include methyl, ethyl, propyl, pentyl, octyl, undecyl and octadecyl groups, alternatively methyl and ethyl groups. The substituted aliphatic hydrocarbon group is preferably a non-halogenated substituted alkyl group.

[0074] Aliphatic non-halogenated organic groups are exemplified by, but not limited to, the following: the above alkyl groups having substituted groups, such as oxygen-containing groups, such as polyoxyalkylene groups, carbonyl groups, alkoxy groups and hydroxyl groups. Examples of aromatic groups or substituted aromatic groups are phenyl groups and substituted phenyl groups having substituted groups as described above.

[0075] Component (a) may alternatively contain D units of structure (I), where one R' is an aliphatic group or an aromatic group, and the other is a fluoroalkyl group, such as trifluoropropyl, trifluoroethyl and nonafluorohexyl groups, or a perfluoroalkyl group, for example, CF 3 -, C 2 F 5 -, C 3 F 7 - such as CF 3 CF 2 CF 2 - or (CF 3 ) 2 CF-, C 4 F 9 - such as CF 3CF 2 CF 2 CF 2 -, (CF 3 ) 2 CFCF 2 -, (CF 3 ) 3 C- and CF 3 CF 2 (CF 3 )CF-; C 5 F 11 such as CF 3 CF 2 CF 2 CF 2 CF 2 -, C 6 F 13 -, such as CF 3 (CF 2 ) 4 CF 2 -; C 7 F 14 -, such as CF 3 (CF 2 CF 2 ) 3 -; and C 8 F 17 -.

[0076] When the substrate is prepared as an intermediate for preparing a compound composition containing a peroxide catalyst, since peroxide curing proceeds via a free radical reaction pathway, although typically such (fluorinated) organosilicones contain two or more alkenyl or alkynyl groups, reactive groups are not required, so the (fluorinated) organosilicone can be free of reactive groups, such as free of alkenyl groups or alkynyl groups, or can even have hydroxyl end groups.

[0077] However, if it is intended to prepare a compound composition that can be hydrosilylated or addition-cured using, for example, a platinum catalyst and a crosslinking agent containing, for example, multiple Si-H bonds, then the (fluorinated) organosilicone requires at least two unsaturated groups per molecule, typically alkenyl or alkynyl groups. When present, the unsaturated groups of component (a) can be located at the ends or side chains of the organopolysiloxane polymer, or at both positions.

[0078] When present, the unsaturated group of component (a) can be an alkenyl group or an alkynyl group as described above. When present, each alkenyl group can contain, for example, 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, alternatively 2 to 6 carbon atoms. When present, the alkenyl group can be exemplified by, but not limited to, the following: vinyl, allyl, methallyl, isopropenyl, propenyl, and hexenyl, as well as cyclohexenyl groups. When present, each alkynyl group can also have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, alternatively 2 to 6 carbon atoms. Examples of alkynyl groups can be exemplified by, but not limited to, the following: ethynyl, propynyl, and butynyl groups. Preferred examples of the unsaturated group of component (a) include vinyl, propenyl, isopropenyl, butenyl, allyl, and 5-hexenyl.

[0079] Thus, the (fluoro)organosilicone can be, for example, trialkyl-capped, alkenyldialkyl-capped, alkynyldialkyl-capped, dialkylsilanol-capped, or can be capped with any other suitable combination of end groups, provided that each polymer has at least 100 mm / 100 Williams plasticity as measured according to ASTM D-926-08.

[0080] Thus, for example, component (a) can be:

[0081] Alkenyldialkyl-capped polydimethylsiloxane, such as dimethylethylene-capped polydimethylsiloxane; alkenyldialkyl-capped dimethylmethylphenylsiloxane, such as dimethylethylene-capped dimethylmethylphenylsiloxane; trialkyl-capped dimethylmethylvinylpolysiloxane; alkenyldialkyl-capped dimethylmethylvinylpolysiloxane copolymer; alkenyldialkyl-capped methylphenylpolysiloxane, alkenyldialkyl-capped methylvinylmethylphenylsiloxane; alkenyldialkyl-capped methylvinyldiphenylsiloxane; alkenyldialkyl-capped methylvinylmethylphenyldimethylsiloxane; trimethyl-capped methylvinylmethylphenylsiloxane; trimethyl-capped methylvinyldiphenylsiloxane; or trimethyl-capped methylvinylmethylphenyldimethylsiloxane or fluoroorganosilicone polymer gum, such as trimethyl-capped polymethyltrifluoropropylsiloxane, dimethyldialkyl-capped polymethyltrifluoropropylsiloxane, such as dimethylethylene-capped polymethyltrifluoropropylsiloxane, dimethylsilanol-capped polymethyltrifluoropropylsiloxane; trimethyl-capped polymethylperfluoropropylsiloxane, dimethyldialkyl-capped polymethylperfluoropropylsiloxane, such as dimethylethylene-capped polymethyltrifluoropropylsiloxane or dimethylsilanol-capped polymethyltrifluoropropylsiloxane.

[0082] In each case, component (a) has a Williams plasticity of at least 100 mm / 100 measured according to ASTM D-926-08, alternatively at least 125 mm / 100 measured according to ASTM D-926-08, alternatively at least 140 mm / 100 measured according to ASTM D-926-08. Generally, the (fluoro)organosilicone has a Williams plasticity of about 100 mm / 100 to 400 mm / 100 measured according to ASTM D-926-08.

[0083] Starting ingredient / component (b)

[0084] Component (b) is at least one reinforcing silica filler. Preferably, the reinforcing silica filler is in a finely divided form. The reinforcing silica filler (b) may be exemplified by: fumed silica, colloidal silica and / or precipitated silica.

[0085] Precipitated silica, fumed silica and / or colloidal silica are particularly preferred because of their relatively high surface area (usually at least 50 m 2 / g (BET method according to ISO 9277:2010)); alternatively, a surface area of 50 m 2 / g to 450 m 2 / g (BET method according to ISO 9277:2010) is usually used, alternatively a surface area of 50 m 2 / g to 300 m 2 / g (BET method according to ISO 9277:2010). All these types of silica are commercially available. The reinforcing silica filler of component (b) is naturally hydrophilic and is treated with one or more treating agents (starting component / component (c)) to make them hydrophobic. Such surface-modified reinforcing fillers are subdivided because they do not agglomerate and can be uniformly incorporated into component (a) because the surface treatment makes the filler easily wetted by the gum (a) to produce the uncatalyzed (fluoro)organosiloxane rubber matrix described herein.

[0086] As described above, the reinforcing filler is introduced into the gum as described above to prepare an uncatalyzed (fluoro)organosiloxane rubber matrix, which contains at least 38% by weight of the reinforcing filler based on the weight of the total basic starting components, usually 39% to 55% by weight, alternatively 39% to 50% by weight, alternatively 39% to 45% by weight of the reinforcing filler based on the weight of the total basic starting components.

[0087] Starting ingredient / component (c)

[0088] Considering that the silica reinforcing filler (b) is naturally hydrophilic, it is generally treated in situ with a hydrophobizing agent during the process unless it has been pretreated to render the surface appropriately hydrophobic. Any suitable agent capable of hydrophobizing the silica surface can be used. For example, the treating agent of the starting ingredient / component (c) can be selected from suitable silanes, polydiorganosiloxanes or silazanes (such as hexamethyldisilazane), short-chain siloxanediols and / or short-chain fluorosiloxanediols to render the silica reinforcing filler (b) hydrophobic, and thus easier to handle and obtain a homogeneous mixture with other components.

[0089] Specific examples of component (c) include, but are not limited to, silanol-terminated trifluoropropylmethylsiloxane, silanol-terminated vinylmethyl (ViMe) siloxane, silanol-terminated methylphenyl (MePh) siloxane, liquid hydroxy dimethyl-terminated polydiorganosiloxane having an average of 2 to 20 repeating units of diorganosiloxane per molecule, hydroxy dimethyl-terminated phenylmethylsiloxane, hexaorganodisiloxanes such as hexamethyldisiloxane and divinyltetramethyldisiloxane; hexaorganodisilazanes, such as hexamethyldisilazane (HMDZ), divinyltetramethyldisilazane and tetramethyldi(trifluoropropyl)disilazane; hydroxy dimethyl-terminated polydimethylmethylvinylsiloxane, octamethylcyclotetrasiloxane and silanes, including but not limited to methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, trichloromethylsilane.

[0090] A small amount of water can be added together with the silica treating agent as a processing aid.

[0091] In one embodiment, when needed, the starting ingredient / component (c) herein comprises a short-chain straight-chain or branched polydiorganosiloxane terminated with dialkylhydroxy or dialkylalkoxy, the short-chain straight-chain or branched polydiorganosiloxane comprising a plurality of the following structural units:

[0092] -((R 10 ) 2 SiO)-,

[0093] wherein each R 10 can be the same or different and is an alkyl group having 1 to 10 carbons, alternatively an alkyl group having 1 to 6 carbons, alternatively methyl, ethyl or propyl, or an aromatic group having 6 to 12 carbons, alternatively phenyl, and the number-average degree of polymerization is in the range between 2 and 50, alternatively 2 and 25. In one embodiment, each R 10Selected from methyl, ethyl, propyl, and phenyl. When present, each terminal alkoxy group typically has from 1 to 6 carbons, but is preferably ethoxy or methoxy. Thus, short-chain linear or branched polydiorganosiloxanes can be selected from dimethyl hydroxy-terminated polydimethylsiloxane, dimethyl methoxy-terminated polydimethylsiloxane, or dimethyl ethoxy-terminated polydimethylsiloxane, wherein the number-average degree of polymerization is from 2 to 25, alternatively 2 to 20; dimethyl hydroxy-terminated polymethylphenylsiloxane, dimethyl methoxy-terminated polymethylphenylsiloxane, or dimethyl ethoxy-terminated polymethylphenylsiloxane, wherein the number-average degree of polymerization is from 2 to 25, alternatively 5 to 20; and / or dimethyl hydroxy-terminated polydimethylmethylphenylsiloxane copolymer, dimethyl methoxy-terminated polydimethylmethylphenylsiloxane copolymer, or dimethyl ethoxy-terminated polydimethylmethylphenylsiloxane copolymer, wherein the number-average degree of polymerization is from 2 to 25, alternatively 2 to 20; for example

[0094] HO-((R 10 ) 2 SiO) x -H

[0095] where x is the number-average degree of polymerization

[0096] The molecular weight values can again be determined by gel permeation chromatography, but polymers at the lower limit of this range, for example those having a DP of about 2 to 20, can be analyzed by gas chromatography-mass spectrometry (GC-MS).

[0097] The surface treatment of the untreated silica reinforcing filler (b) can be carried out before introduction into the composition or in situ (i.e., in the presence of at least a portion of the other components of the composition herein, by blending these components together at about 25 °C or higher temperature until the filler is completely treated). Generally, the untreated silica reinforcing filler (c) is treated in situ with a treating agent in the presence of component (a), which results in the preparation of an uncatalyzed (fluoro)organosiloxane rubber matrix as described above.

[0098] Component (c) can be present in an amount of from 0.1 wt% to 20 wt% of the total base starting components, alternatively from 0.5 wt% to 15 wt% of the total base starting components, alternatively from 1 wt% to 10 wt% of the total base starting components.

[0099] Optional base ingredient

[0100] Optionally, a small amount of water, such as up to 3 wt% of the total base starting components, can be added together with component (c) as a processing aid to facilitate hydrolysis and enhance the treatment effect. Specifically, this is the case when component (c) is a hexaorganodisilazane such as hexamethyldisilazane (HMDZ).

[0101] If desired or deemed necessary, during step (i), step (v) or both step (i) and step (v) of the method, additional organosilicon polymers, fluorinated organosilicon polymers or copolymers thereof having the structure defined for component (a) may additionally be incorporated into the matrix. These may be gums having a Williams plasticity of less than 100 mm / 100 and / or may be organosilicon polymers, fluorinated organosilicon polymers or copolymers thereof having a viscosity at 25 °C of from 10,000 mPa·s to 500,000 mPa·s at 25 °C, the viscosity being measured using a rotational viscometer (designed for viscosities in the range of 1,000 mPa·s - 2,000,000 mPa·s) and adjusting the speed, for example 6 rpm, according to the polymer viscosity; and the vinyl content is at most 10 wt% for each respective polymer.

[0102] When added, the cumulative total amount of such additional organosilicon polymers, fluorinated organosilicon polymers or copolymers thereof that may be added in step (i), step (v) or both step (i) and step (v) is 10 wt% of the total base starting components, alternatively the amount is at most 7.5 wt% of the total base starting components, alternatively the amount is at most 5.0 wt% of the total base starting components.

[0103] For the avoidance of doubt, the total base starting components are starting components (a), (b), (c) and any additional components introduced to form the base composition / mix.

[0104] In the method herein for preparing an uncatalyzed (fluorinated) organosilicon rubber matrix, the following steps are provided:

[0105] (i) introducing the one or more organosilicon polymers, fluorinated organosilicon polymers or copolymers thereof as a first starting component into the mixing chamber of a mixer at about 25 °C, optionally in an inert atmosphere, and mixing, the one or more organosilicon polymers, fluorinated organosilicon polymers or copolymers thereof having in each case a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08;

[0106] (ii) gradually introducing one or more reinforcing fillers as a second starting component and optionally a third starting component, one or more hydrophobic filler treating agents into the mixing chamber of the mixer while continuing to mix until the mixer has been charged with a predetermined amount of reinforcing fillers of at least 38 wt% of the total base starting components to form a base mixture;

[0107] (iii) Optionally, maintain the temperature of the base mixture in the mixing chamber within a predetermined range of 100°C to 200°C for a period of up to 6 hours to remove volatiles from the base mixture of step (ii), thereby forming the base mixture of step (iii), which can be carried out under vacuum in use;

[0108] (iv) Cool the resulting base mixture of step (ii) or step (iii) to a temperature of 25°C to 120°C; and before, during, or after step (iv);

[0109] (v) Reduce the weight percentage of reinforcing filler in the base mixture of step (ii) or step (iii) by mixing the base mixture of step (ii) or 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

[0110] to a predetermined amount to form an uncatalyzed (fluoro)silicone rubber matrix.

[0111] Step (v) can be carried out before, during, or after step (iv). Generally, if required, when preparing the matrix, step (v) is carried out before or during step (iv). When preparing the (fluoro)silicone rubber compound composition as described herein, the above step (v) is necessary, and there is an additional step (vi) that occurs simultaneously with or after step (v). Step (vi) is

[0112] (vi) Introduce at least one catalyst or vulcanizing agent and optionally one or more additives selected from crosslinking agents, curing inhibitors, additional fillers, pigments, property modifiers, etc.

[0113] Focusing on the manufacture of (fluoro)silicone rubber matrix, as previously shown, at least the mixer for steps (i), (ii), and (iii) is a conical screw extruder including a conical twin - screw mixing chamber that houses two counter - rotating conical screws that converge towards an extrusion die head having an inlet and an outlet, wherein the passage through the extrusion die head is controlled by a shut - off device such that the outlet of the extrusion die head is adapted to be closed by the shut - off device as required until the end of step (iii), (iv), or (v), and is appropriately opened after one of the steps selected in step (iii), (iv), or (v), depending on whether or when the uncatalyzed (fluoro)silicone rubber matrix will be further processed or stored outside the conical screw extruder.

[0114] The blocking device is in the form of a plate that is movable between an open position and a closed position such that in the closed position, the blocking device is designed to prevent the content of the conical screw extruder from flowing out during the production of the uncatalyzed (fluorinated) silicone rubber matrix, and in the open position, to allow the uncatalyzed (fluorinated) silicone rubber matrix product to flow out through the extrusion die. Two intermeshing conical screws operate in a counter-rotating manner and are driven by a motor that forms part of the conical screw extruder. If desired, the intermeshing conical screws may include lip seals on the shafts. The conical screw extruder may include a plurality of inlets for, for example, rubber, reinforcing fillers, and treating agents. In each case, these components may be stored in any preferred manner before being introduced into the conical screw extruder. They may also be designed such that a predetermined amount thereof can be metered periodically into the mixing chamber of the conical screw extruder for mixing and preparing the uncatalyzed (fluorinated) silicone rubber matrix. The starting components for the method of producing the uncatalyzed (fluorinated) silicone rubber matrix may be maintained in an inert atmosphere, typically a nitrogen atmosphere. In addition, before introducing the starting components (a), (b), and (c) and during the preparation of the uncatalyzed (fluorinated) silicone rubber matrix, once the fillers have been completely introduced into the mixer, the mixing chamber of the conical screw extruder can be purged with nitrogen. In addition, a typical conical screw extruder has a clamshell opening design that allows for easy cleaning if needed during use as a conical screw extruder. It has also been determined that very little or no dumping and scraping are required between polymer batches due to the small loss of the total batch weight remaining in the mixer after extrusion (heel). This also has the advantage of reducing the labor intensity of the method and further limiting the risk of operator exposure to the starting components and by-products involved in the polymerization method described herein.

[0115] Additionally, the conical screw extruder may have an integrated vacuum system capability, allowing the use of vacuum during step (iii) for removing volatiles. Examples of such conical screw extruders are described in US7556419 and US2021113975, both of which are incorporated herein by reference, and such conical screw extruders are commercially available from Colmec SpA, Busto Arsizio, Italy.

[0116] In the method described herein, during mixing, the base mixture is driven towards the extrusion die by a pair of counter-rotating conical screws and then forced back when the extrusion die is closed by the blocking device. Compared to conventional mixers, this mixing method unexpectedly and surprisingly seems to be able to mix a larger amount of filler into the rubber.

[0117] Conventional mixers (such as Banbury type mixers or sigma blade mixers) that have been used to prepare (fluorinated) organosilicon rubber matrices only seem to be able to incorporate up to a maximum of about 35 wt% of reinforcing silica filler of the total base starting components for making the gum into a matrix. If any more filler is introduced into the mixer, the filler will not be fully incorporated into the gum, and the gum / filler mixture will tend to crumble and never come together. Typically, the excess filler will be drawn out through vents etc., or will remain in the mixing chamber in powder form, thus contributing to an unblocky organosilicon rubber matrix.

[0118] Hindsight suggests that the 35 wt% maximum may be due to, for example, the mixing mechanism of the sigma blades, where when initial mixing occurs, the material is "grabbed" and pulled into the mixing trough for mixing, but as the viscosity / Williams plasticity increases, this becomes increasingly difficult and the partially prepared matrix becomes too hard to pull the remaining portion into the base composition, or considering the mixing mechanism of the mixer used, when the filler loading increases to the functional saturation level, the matrix becomes powdery due to the inability to re-aggregate. Surprisingly, the methods described herein seem to be able to incorporate a greater proportion of filler into the gum without such problems.

[0119] In step (i) of the (fluorinated) organosilicon rubber matrix manufacturing method, one or more organosilicon polymers, fluorinated organosilicon polymers or their copolymers ((fluorinated) organosilicones) having a Williams plasticity of at least 100 mm / 100 in each case according to ASTM D - 926 - 08 are introduced into a conical twin-screw mixing chamber through a suitable inlet.

[0120] The (fluorinated) organosilicone is typically introduced at about 25 °C, after which the gum is mixed. In use, one or more (fluorinated) organosilicones that have been introduced into the conical twin-screw extruder mixing chamber are driven towards the extrusion die by the counter-rotating screws. However, when the shut-off device is closed, they are forced to move back into the conical twin-screw extruder mixing chamber for further recirculation / additional mixing, thus enhancing the uniformity of the (fluorinated) organosilicone. The two counter-rotating screws are in converging and intersecting conical channels, where the outer peripheral profile of the screw threads extends adjacent to the channel surfaces. Thus, before preparing the matrix in step (ii), when the (fluorinated) organosilicone approaches the closed extrusion die, the material is forced along the conical profile of the screw to a gradually narrowing volume, thereby increasing the pressure. This can optionally be carried out in an inert atmosphere. During the (fluorinated) organosilicon rubber matrix manufacturing method, during the shear heating of the uncatalyzed (fluorinated) organosilicon rubber matrix, the material introduced into the conical twin-screw extruder gradually heats up, possibly up to around 200 °C.

[0121] (Fluoro)organosilicones 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 metering addition method, such as a screw automatic metering addition method from a rubber hopper, etc. If mixing is carried out under an inert atmosphere, the method for manufacturing the (fluoro)organosilicone rubber matrix is usually carried out in a nitrogen atmosphere.

[0122] In the case of using two or more (fluoro)organosilicones (a), if necessary, these rubbers can be premixed in a suitable mixer before entering the conical twin-screw extruder so that the different (fluoro)organosilicones (a) are thoroughly intermingled when introduced into the conical twin-screw extruder. Alternatively, when using more than one (fluoro)organosilicone (a), the corresponding (fluoro)organosilicones (a) can be introduced into the conical screw tablet press simultaneously or by any other suitable mixing method, such as introducing one (fluoro)organosilicone (a) at the start of the method for manufacturing the (fluoro)organosilicone rubber matrix and introducing aliquots of a second (fluoro)organosilicone (a) periodically during the method for manufacturing the (fluoro)organosilicone rubber matrix, or introducing a certain amount of the first (fluoro)organosilicone (a) and then introducing a certain amount of the second (fluoro)organosilicone (a) and repeating if appropriate. Then, before introducing the reinforcing filler (b) and the treating agent (c), these rubbers can be thoroughly mixed together in the conical twin-screw extruder, if this is necessary in the latter case to prepare the uncatalyzed (fluoro)organosilicone rubber matrix.

[0123] In step (ii) of the method for manufacturing a (fluorinated) organosilicon rubber matrix, one or more reinforcing fillers and optionally one or more hydrophobic filler treatment agents are gradually introduced into a conical twin-screw extruder while continuing mixing until the mixer has been charged with a predetermined amount of reinforcing filler of at least 38% by weight, typically 39% to 55% by weight, alternatively 39% to 50% by weight, alternatively 39% to 45% by weight, based on the weight of the total basic starting components; to form a base mixture. The reinforcing filler (b) can be introduced into the conical twin-screw extruder via any suitable powder metering addition device compatible therewith. For example, it can be metered in via one or more hoppers or even manually from a bag, etc. When required, the treatment agent (c) can be metered in using any suitable means, such as automatically metered from a tank, but can also alternatively be manually fed as required and when required. Generally, when the treatment agent (c) is required, as can be expected in most cases, the reinforcing filler (b) and the treatment agent (c) can be introduced into the conical twin-screw extruder in any order, i.e., one before the other or simultaneously. If required, they can be gradually introduced or periodically introduced at a predetermined rate during the mixing process. The mixing in step (ii) of the method for manufacturing a (fluorinated) organosilicon rubber matrix can also be carried out in a nitrogen atmosphere, for example by using periodic introduction of nitrogen to control the oxygen level in the mixer during mixing.

[0124] In step (ii) of the method for manufacturing a (fluorinated) organosilicon rubber matrix, the reinforcing filler (b) is introduced into the (fluorinated) organosilicone (a) using a conical screw tablet press, and the reinforcing filler (b) is treated in situ with the treatment agent (c) so that the outer surface of the reinforcing filler has hydrophobicity and is thus more easily wetted by the (fluorinated) organosilicone (a) and introduced therein.

[0125] In use, assuming that a treating agent (c) is required, components (b) and (c) are introduced into a conical screw extruder that already contains component (a). The ingredients for preparing the matrix, namely components (a), (b), and (c), are then mixed in the same manner as previously described for step (i), i.e., in the mixing chamber of the conical screw extruder, they are driven towards the extrusion die by counter-rotating screws, where the shut-off device is closed so that they are forced to move back into the conical twin-screw mixing chamber for further recirculation / additional mixing to enhance the homogeneity of the uncatalyzed (fluoro)silicone rubber matrix during preparation. The two counter-rotating screws are located in convergent and intersecting conical channels, where the outer peripheral profile of the threads extends adjacent to the channel surface. Thus, during the production method of the uncatalyzed (fluoro)silicone rubber matrix product, as the ingredients and / or the uncatalyzed (fluoro)silicone rubber matrix product approach the closed extrusion die, the material is forced along the conical profile of the screw to a progressively narrowing volume, thereby increasing the pressure. This pressure increase enables the recirculation of the contents of the mixing chamber. If desired, for example, when it is considered that the production process of the uncatalyzed (fluoro)silicone rubber matrix is approaching completion, the rotation of the two screws can also be temporarily reversed to assist in the mixing or cooling process. PTFE packing can be used on the shaft of the conical screw, and in one embodiment, if desired, the screw can include a lip seal on the shaft of the screw. Generally, step (ii) of the (fluoro)silicone rubber matrix manufacturing method is carried out at a temperature of about 50°C to 120°C, alternatively about 50°C to 100°C, alternatively about 50°C to 80°C, which generally depends on the hydrophobic agent (c) used. Although chain extension is not typically used when preparing the matrix from (fluoro)silicone rubber, if chain extension is required for any reason, it is generally carried out during step (ii). Thus, if desired, a chain extender can be added to the conical screw extruder during step (ii) of the method so that chain extension can occur during step (ii) and / or step (iii) of the method for preparing the matrix.

[0126] In step (iii) of the method for manufacturing a (fluorinated) organosilicon rubber matrix, the temperature of the mixing chamber is optionally maintained within a predetermined range of 100 °C to 200 °C for a period of up to 6 hours to remove volatiles and thermodynamically promote silica treatment. When used, step (iii) can be carried out under vacuum, and heating may be required if / when the heat generated during shear mixing in step (ii) does not generate sufficient heat to ensure that the temperature is maintained within the desired range in step (iii) while removing volatiles. The volatiles generated during step (ii) of the method for manufacturing a (fluorinated) organosilicon rubber matrix are removed while mixing can continue. Depending on the volatiles envisaged to be present due to the ingredients used, in particular depending on the treatment agent (c) used, when required, the mixing chamber of the conical twin-screw extruder is maintained at a suitable temperature, i.e., within a predetermined range of 100 °C to 200 °C, for a period of up to 6 hours to remove volatiles as required and when required.

[0127] In step (iv) of the method for manufacturing a (fluorinated) organosilicon rubber matrix, the resulting base mixture from step (ii) and optionally step (iii) is cooled to a temperature of 25 °C to 120 °C, thereby providing an uncatalyzed (fluorinated) organosilicon rubber matrix containing at least 38% by weight of reinforcing filler that can be further processed or stored. The temperature to which the uncatalyzed (fluorinated) organosilicon rubber matrix needs to be cooled depends on whether it is to be used for further processing, i.e., compounding in which a catalyst and optionally additives are introduced, or whether the uncatalyzed (fluorinated) organosilicon rubber matrix is to be stored, e.g., packaged for future use or sale.

[0128] Thus, for example, if the uncatalyzed (fluorinated) organosilicon rubber matrix is to be stored and / or packaged, the cooling needs to be reduced to a low enough temperature to prevent the packaging material from melting. For example, in the case of polyethylene, it must be cooled to a temperature not exceeding 90 °C. For example, it can be cooled to a predetermined temperature of about 30 °C to 80 °C, alternatively about 30 °C to 70 °C, alternatively about 40 °C to 70 °C. The cooling step (iv) of the method for manufacturing a (fluorinated) organosilicon rubber matrix can be carried out, for example,

[0129] (I) entirely in the conical screw tablet press used to prepare the uncatalyzed (fluorinated) organosilicon rubber matrix, in which case the resulting uncatalyzed (fluorinated) organosilicon rubber matrix is cold extruded at a temperature in the range of 30 °C to 40 °C;

[0130] (II) Partially in the conical screw extruder used for preparing the uncatalyzed (fluoro)organosiloxane rubber matrix, in which case the resulting uncatalyzed (fluoro)organosiloxane rubber matrix is extruded at a moderate temperature in the range of 50 °C to 80 °C and then transferred to an alternative device for further cooling, such as a tray or other container; or

[0131] (III) Entirely outside the conical screw extruder used for preparing the uncatalyzed (fluoro)organosiloxane rubber matrix, in which case the resulting uncatalyzed (fluoro)organosiloxane rubber matrix 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 device for cooling, such as a second "cooling" conical screw extruder, a tray or other container, in which case the conical screw extruder used for preparing the uncatalyzed (fluoro)organosiloxane rubber matrix can be reused to immediately prepare another batch of uncatalyzed (fluoro)organosiloxane rubber matrix from components (a), (b) and (c).

[0132] If the conical screw extruder used for preparing the uncatalyzed (fluoro)organosiloxane rubber matrix is also used to cool the matrix to about 25 °C, this may increase costs and time and will reduce the plant output, so such options (iv)(II) and (iv)(III) are preferred.

[0133] Optional step (v) can be carried out before, during or after step (iv). Generally, if required, step (v) is carried out before or during step (iv) when preparing the matrix.

[0134] If required, after step (iv) or (v), the resulting product of step (iv) or step (v) can be granulated or dusted with a suitable powder before storage to facilitate future use, such as as a main component in a compounding process. Any suitable method can be used to granulate the product, and this resulting granulated product can be considered a preferred storage form before compounding. Similarly or alternatively, the base composition can be dusted with a suitable powder (such as talc) for future use after storage.

[0135] However, in one embodiment, the conical screw tablet press used to prepare the uncatalyzed (fluoro)organosiloxane rubber matrix can be used to prepare the uncatalyzed (fluoro)organosiloxane rubber matrix, and then step (iv)(I) can be used, such that it can also be a means of compounding the cooled uncatalyzed (fluoro)organosiloxane rubber matrix with other additives in the conical screw tablet press before its extrusion. In this case, during the production method of the uncatalyzed (fluoro)organosiloxane rubber matrix, for example, in the above steps (i) to (iii), this step (iv), and the above compounding steps (v) and (vi), the occlusion device remains in the closed position.

[0136] Subsequently, once the product of step (iii) of the uncatalyzed (fluoro)organosiloxane rubber matrix has cooled to the desired temperature for discharge from the conical screw tablet press used to prepare the uncatalyzed (fluoro)organosiloxane rubber matrix, the occlusion device is moved to the open position to allow the resulting uncatalyzed (fluoro)organosiloxane rubber matrix product to be extruded through the extrusion die. The extrusion die has an inlet and an outlet, and the passage through the extrusion die from the inlet in the conical screw tablet press to the outlet is controlled by the above occlusion device.

[0137] The uncatalyzed (fluoro)organosiloxane rubber matrix product flowing out of the conical screw tablet press through the extrusion die is collected for further cooling and / or step (v), or is collected and transferred to a suitable packaging device, or is conveyed to a compounding device for the above steps (v) and (vi) to prepare a curable rubber compound composition, etc. In the case of further cooling, it can be extruded into a bulk barrel or other container, or can be passed directly through a gear pump and then packaged.

[0138] In one embodiment, another conical screw tablet press with a gear pump or a conical twin-screw extruder in which the matrix can be tensioned and packaged, or alternatively any suitable compounding device, such as a Sigma blade kneader mixer, a bottom discharge kneader mixer, a conical screw tablet press, a planetary extruder, a co-kneader extruder, a twin-screw extruder, a single-screw extruder, and / or a two-roll mill, is used to extrude the matrix flowing out of the conical screw tablet press into another device for further processing, such as steps (v) and optionally step (vi) as described above, but in this case, in a preferred embodiment, it can be a second conical screw tablet press.

[0139] In one embodiment, the method for preparing an uncatalyzed (fluoro)organosiloxane rubber matrix forms part of a continuous compounding method, for example, there may be a cascade of conical screw extruders used, where a first conical screw extruder can be used to prepare an organosiloxane rubber compound, such as described in WO2023219834, a second conical screw extruder can be used to prepare the uncatalyzed (fluoro)organosiloxane rubber matrix as described above, a third conical screw extruder can be used at least partially for the cooling step (iv) and subsequently for packaging, and optionally partially for the cooling step (iv) and step (v) and optionally (vi), or the third conical screw extruder can extrude the cooled uncatalyzed (fluoro)organosiloxane rubber matrix into a fourth conical screw extruder, which can be used with a catalyst and other additives for steps (v) and (vi) to form a curable organosiloxane rubber compound composition.

[0140] Typically, when compounding the uncatalyzed (fluoro)organosiloxane rubber matrix as described above, step (v) is first carried out, where an additional amount of (fluoro)organosiloxane gum is introduced and mixed with the product obtained in step (iv). The amount of the additional (fluoro)organosiloxane gum is pre-determined to ensure the correct level of filler in the final compound composition produced by step (vi). If desired, one or more organopolysiloxane polymers identified as the above additional base components can be additionally introduced during step (v). Thus, such optional components (when present) are typically introduced into the matrix during step (i), (ii) or (v), alternatively during step (i) or (v). If appropriate, step (v) can be carried out, and then the product of step (v) can be packaged and stored so that step (vi) can be carried out later indoors or by a third party. Alternatively, step (vi) can be carried out simultaneously with step (v), or after step (v) together with the product of step (v).

[0141] The catalyst, crosslinker (when required), and optionally the additives are ideally all metered in, depending on the equipment used, but if necessary, some small volumes of additives can be introduced manually, although this is generally not preferred.

[0142] After the cooling step (iv), the compounding of the uncatalyzed (fluoro)organosiloxane rubber matrix must be carried out at a temperature below the curing temperature of the catalyst, which is typically a peroxide and is usually one of the additives used in compounding. Thus, for most peroxides, it is preferred to carry out the compounding at a temperature below 50 °C, but for some catalysts, the compounding can be carried out at a temperature up to about 120 °C.

[0143] The compounding device used in step (vi) can be any suitable compounding machine mixer, such as a Sigma blade kneader mixer, a bottom discharge kneader mixer, a conical twin screw mixer (e.g., a screw tablet press), 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, it can be a second conical screw tablet press.

[0144] Once the above method is completed, the resulting uncatalyzed (fluoro)organosiloxane rubber matrix can be stored for future use or can be used to prepare a curable compound composition by introducing a catalyst, a crosslinking agent, etc. into the matrix.

[0145] First, the uncatalyzed (fluoro)organosiloxane rubber matrix can be diluted by introducing an additional amount of one or more (fluoro)organosiloxanes as defined above in component (a), optionally together with one or more organopolysiloxane polymers identified as additional base components, in order to reduce the filler content in the uncatalyzed (fluoro)organosiloxane rubber matrix before introducing other additives. Any suitable amount of (fluoro)organosiloxane can be introduced as needed and when needed. In fact, if desired, the uncatalyzed (fluoro)organosiloxane rubber matrix can be diluted with a (fluoro)organosiloxane different from the (fluoro)organosiloxane initially used to prepare the uncatalyzed (fluoro)organosiloxane rubber matrix.

[0146] Generally, when using an uncatalyzed (fluoro)organosiloxane rubber matrix made of an organosiloxane and / or a fluoroorganosiloxane polymer gum, a favorable catalyst used is a suitable organic peroxide or its selection. Suitable organic peroxides include substituted or unsubstituted dialkyl peroxides, alkyl aryl acyl peroxides, diacyl peroxides, such as benzoyl peroxide and 2,4-dichlorobenzoyl peroxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, bis(tert-butyl dioxy)diisopropylbenzene, bis(tert-butylperoxy)-2,5-dimethylhex-3-yne, 2,4-dimethyl-2,5-bis(tert-butylperoxy)hexane, di-tert-butyl peroxide, and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane. Mixtures of the above can also be used.

[0147] Generally, the amount of the free radical curing agent used in a high-consistency rubber composition as described herein is in each case 0.2% to 3% by weight, alternatively 0.2% to 2% by weight, based on the weight of the composition.

[0148] Alternatively, but less favorable for such base materials, is a hydrosilylation curing (also known as addition curing) package, which comprises

[0149] (i) A crosslinking agent in the form of a silicone compound having at least two, alternatively at least three, Si-H groups per molecule; and

[0150] (ii) A hydrosilylation catalyst comprising, consisting of, or composed of a platinum group metal or its compound.

[0151] The silicone compound (i) serves as a crosslinking agent and is provided in the form of a silicone compound having at least two, alternatively at least three, Si-H groups per molecule. The silicone compound (i) of the liquid silicone rubber composition usually 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 structure therewith, and thereby cure the composition. When the polymer (a) has more than two unsaturated groups per molecule, some or all of the silicone compound (i) can alternatively have two silicon-bonded hydrogen atoms per molecule.

[0152] The molecular configuration of the silicone compound having at least two, alternatively at least three, Si-H groups per molecule (silicone compound (i)) is not particularly limited. It can be a linear, branched (linear with some branches through the presence of T groups), cyclic, or silicone resin-based polyorganosiloxane.

[0153] Although the molecular weight of the silicone compound (i) is not particularly limited, using the test method as described for component (a), the viscosity at 25 °C is usually 5 mPa·s to 50,000 mPa·s.

[0154] The silicon-bonded organic groups used in the silicone compound (i) can be exemplified by: alkyl groups such as methyl, ethyl, propyl, n-butyl, tert-butyl, pentyl, hexyl; aryl groups such as phenyl, tolyl, xylyl or similar aryl groups; 3-chloropropyl, 3,3,3-trifluoropropyl or similar haloalkyl groups, preferably alkyl groups having 1 to 6 carbons, especially methyl, ethyl or propyl groups or phenyl groups. Preferably, the silicon-bonded organic groups used in the silicone compound (i) are alkyl groups, alternatively methyl, ethyl or propyl groups.

[0155] Examples of the silicone compound having at least two, alternatively at least three, Si-H groups per molecule of the silicone compound (i) include, but are not limited to:

[0156] (a’) Methylhydrogenpolysiloxane endblocked with trimethylsilyloxy

[0157] (b’) Polydimethylsiloxane-methylhydrogensiloxane endblocked with trimethylsilyloxy

[0158] (c’) Dimethylhydrogensiloxy-terminated dimethylsiloxane-methylhydrogensiloxane copolymer,

[0159] (d’) Dimethylsiloxane-methylhydrogensiloxane cyclic copolymer,

[0160] (e’) Copolymer and / or silicone resin composed of (CH 3 ) 2 HSiO 1 / 2 units, (CH 3 ) 3 SiO 1 / 2 units and SiO 4 / 2 units,

[0161] (f’) Copolymer and / or silicone resin composed of (CH 3 ) 2 HSiO 1 / 2 units and SiO 4 / 2 units,

[0162] (g’) Methylhydrogensiloxane cyclic homopolymer having 3 to 10 silicon atoms per molecule;

[0163] Optionally, the silicone compound (i) crosslinking agent can be a filler, such as silica treated with one of the above substances, and mixtures thereof.

[0164] In one embodiment, the silicone compound (i) is selected from methylhydrogenpolysiloxane terminated with trimethylsilyloxy groups at both molecular ends; copolymer of methylhydrogen siloxane and dimethylsiloxane terminated with trimethylsilyloxy at both molecular ends; dimethylsiloxane terminated with dimethylhydrogensiloxy groups at both molecular ends; copolymer of methylhydrogen siloxane and dimethylsiloxane terminated with dimethylhydrogensiloxy at both molecular ends.

[0165] The crosslinking agent silicone compound (i) is present in the compound composition in an amount such that the molar ratio of the total number of organosilicon-bonded hydrogen atoms in the silicone compound (i) to the total number of alkenyl and / or alkynyl groups in component (a) is from 0.5:1 to 10:1. When the ratio is less than 0.5:1, a well-cured elastomeric material is not obtained. When the ratio exceeds 10:1, there is a tendency for the hardness of the cured elastomeric material to increase when heated. Preferably, the amount of the silicone compound (i) is such that the molar ratio of the silicon-bonded hydrogen atoms of the silicone compound (i) to the alkenyl / alkynyl groups, optionally alkenyl groups, of component (a) is in the range of 0.7:1.0 to at most 5.0:1.0, optionally 0.9:1.0 to 2.5:1.0, and additionally optionally 0.9:1.0 to 2.0:1.0.

[0166] The Si-bonded hydrogen (Si-H) content of the organosilicon compound (i) is determined by quantitative infrared analysis in accordance with ASTM E168. In this case, when relying on a hydrosilylation curing process, the ratio of Si-bonded hydrogen to alkenyl (vinyl) and / or alkynyl groups is important. Generally speaking, this is determined by calculating the total weight % of alkenyl groups (such as vinyl) [V] in the composition and the total weight % of Si-bonded hydrogen [H] in the composition, and assuming that the molecular weight of hydrogen is 1 and the molecular weight of vinyl is 27, the molar ratio of Si-bonded hydrogen to vinyl is 27[H] / [V].

[0167] Typically, depending on the number of unsaturated groups in component (a) and the number of Si-H groups in the organosilicon compound (i), the organosilicon compound (i) will be present in the following amounts: 0.1 wt% to 10 wt% of the compound composition, alternatively 0.1 wt% to 7.5 wt% of the compound composition, alternatively 0.5 wt% to 7.5 wt%, and further alternatively 0.5 wt% to 5 wt% of the compound composition.

[0168] The hydrosilylation catalyst (ii) comprises or consists of a platinum group metal or a compound thereof. These catalysts are generally selected from catalysts of platinum group metals (platinum, ruthenium, osmium, rhodium, iridium, and palladium), or compounds of one or more of such metals. Alternatively, due to the high activity level of these catalysts in the hydrosilylation reaction, platinum and rhodium compounds are preferred, 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.

[0169] The hydrosilylation catalyst (ii) can be a platinum group metal, a platinum group metal deposited on a support (such as activated carbon, metal oxides such as alumina or silica, silica gel, or charcoal powder), or a compound or complex of a platinum group metal. Preferably, the platinum group metal is platinum.

[0170] 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 catalyst)), chloroplatinic acid in a solution of an alcohol (such as isooctanol or pentanol) (Lamoreaux catalyst), and complexes of chloroplatinic acid with ethylenically unsaturated compounds (such as olefins) and organosiloxanes containing ethylenically unsaturated Si-bonded hydrocarbon groups, such as tetraethenyltetramethylcyclotetrasiloxane-platinum complex (Ashby catalyst). Soluble platinum compounds that can be used include, for example, the formula (PtCl 2 . Olefins) 2 and H(PtCl3 Platinum-olefin complexes of olefins), and in this context olefins having 2 to 8 carbon atoms are preferably used, 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. Other soluble platinum catalysts are, for example, of the formula (PtCl 2 C 3 H 6 ) 2 Platinum-cyclopropane complexes, reaction products of hexachloroplatinic acid with alcohols, ethers and aldehydes or mixtures thereof, or reaction products of hexachloroplatinic acid and / or its transformation products with vinylsiloxanes (such as methylvinylcyclotetrasiloxane) in the presence of an ethanol solution containing sodium bicarbonate. Platinum catalysts having phosphorus and amine ligands can also be used, for example (Ph 3 P) 2 PtCl 2 ; and complexes of platinum with vinylsiloxanes, such as symmetric divinyltetramethyldisiloxane.

[0171] Thus, specific examples of suitable platinum-based catalysts include:

[0172] (i) Complexes of chloroplatinic acid with organosiloxanes containing ethylenically unsaturated hydrocarbon groups as described in US 3,419,593;

[0173] (ii) Chloroplatinic acid in the form of the hexahydrate or the anhydrous form;

[0174] (iii) Platinum-containing catalysts obtained by a method comprising the step of reacting chloroplatinic acid with an aliphatic unsaturated organosilicon compound (such as divinyltetramethyldisiloxane);

[0175] (iv) Olefin-platinum-silyl complexes as described in US Patent 6,605,734, such as (COD)Pt(SiMeCl 2 ) 2 , where "COD" is 1,5-cyclooctadiene; and / or

[0176] (v) Karstedt catalyst, platinum divinyltetramethyldisiloxane complex, typically containing about 1 wt% of platinum in a vinylsiloxane polymer having a viscosity of about 200 to 750 as measured by the test method described for component (a).

[0177] Solvents such as toluene and similar organic solvents have been used historically as alternatives, but the use of vinyl siloxane polymers is the preferred choice so far. These are described in US3,715,334 and US3,814,730. In a preferred embodiment, the hydrosilylation catalyst (ii) can be selected from coordination compounds of platinum. In one embodiment, chloroplatinic acid and its conversion products with vinyl-containing siloxanes, Karstedt catalyst and Speier catalyst are preferred.

[0178] The hydrosilylation catalyst (ii) is generally present in an amount providing 0.1 ppm to 500 ppm (parts per million) of platinum atoms by weight relative to the reactive components, namely components (a) and (c1(ii)). The catalyst can be added as a single substance or as a mixture of two or more different substances. Generally, depending on the form / concentration of the hydrosilylation catalyst (ii) provided, the amount of catalyst present will be in the range of 0.05 wt% - 1.5 wt%, alternatively 0.05 wt% - 1.0 wt%, alternatively 0.1 wt% - 1.0 wt%, alternatively 0.1 wt% to 0.5 wt% of the composition, where the platinum catalyst is provided in the masterbatch of the polymer (such as (a) as described above).

[0179] During the compounding process, a variety of other additives can be added to the uncatalyzed (fluoro)organosiloxane rubber matrix.

[0180] Optional additive

[0181] In each case, various optional additives suitable for the application of the elastomer produced by curing can also be incorporated into the composition. Examples include cure inhibitors (usually when incorporated into the hydrosilylation cure package), mold release agents, extender fillers, adhesion catalysts, rheology modifiers, conductive fillers, heat conductive fillers, shelf life extenders, acid acceptors, lubricants, heat stabilizers, compression set additives, UV light stabilizers, fungicides, wetting agents, pigments and colorants, flame retardants and plasticizers, etc.

[0182] Curing inhibitor

[0183] When needed, i.e., in the case of using a hydrosilylation (addition) curing system instead of peroxide, a curing inhibitor is used. They are used to prevent or delay the curing process of the addition reaction, especially during storage. Optional addition reaction inhibitors for platinum-based catalysts are well known in the art and include hydrazine, triazole, phosphine, thiol, organic nitrogen compounds, alkynols, methanesilylated alkynols, maleate, fumarate, ethylenically or aromatically unsaturated amides, ethylenically unsaturated isocyanates, vinyl siloxanes, unsaturated hydrocarbon monoesters and diesters, conjugated enyne, hydroperoxides, nitriles, and diaziridines. Vinylically substituted siloxanes as described in US3989667 can be used, where cyclic methyl vinyl siloxanes are preferred.

[0184] A class of known hydrosilylation reaction inhibitors are the acetylenic compounds disclosed in US3445420. Alkynols such as 2-methyl-3-butyn-2-ol constitute a preferred class of inhibitors, which will inhibit the activity of platinum-containing catalysts at 25 °C. Compositions containing these inhibitors generally need to be heated at a temperature of 70 °C or above in order to cure at an achievable rate.

[0185] Examples of alkynols 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. Alkynol derivatives can include those compounds having at least one silicon atom.

[0186] When present, an inhibitor concentration as low as 1 mole of inhibitor / mole of catalyst metal will, in some cases, confer satisfactory storage stability and curing rate. In other cases, an inhibitor concentration of up to 500 moles of inhibitor / mole of catalyst metal is required. The optimal concentration of a given inhibitor in a given composition can be readily determined by routine experimentation. Depending on the concentration and form in which the selected inhibitor is provided / commercially available, when present in the composition, the inhibitor is generally present in an amount of 0.0125% to 10% by weight of the composition.

[0187] In one embodiment, when present, the inhibitor is selected from 1-ethynyl-1-cyclohexanol (ETCH) and / or 2-methyl-3-butyn-2-ol, and is present in an amount of greater than zero to 0.1% by weight of the composition.

[0188] Release agent

[0189] Any suitable release agent can be utilized. For example, it can be a hydroxyl dimethyl terminated polydimethylsiloxane having a viscosity at 25 °C of from 10 mPa·s to 200 mPa·s, which viscosity is measured at 12 rpm using a Brookfield rotational viscometer having a cone and plate arrangement with cone CP-52. Tm Rotational viscometer at 12 rpm.

[0190] Extender filler

[0191] The extender fillers can include, such as, ground quartz, diatomaceous earth, barium sulfate, iron oxide, titanium dioxide, and carbon black, talc, wollastonite. Other fillers that can be used alone or in addition to the above include bauxite, calcium sulfate (anhydrite), gypsum, calcium sulfate, clays such as kaolin, aluminum trihydrate, graphite, copper carbonate such as malachite, nickel carbonate such as violarite, barium carbonate such as witherite, and / or strontium carbonate such as strontianite.

[0192] Other extender fillers can include alumina, silicates selected from the group consisting of: olivines; garnets; aluminosilicates; ring silicates; chain silicates; and sheet silicates. The olivines include silicate minerals such as, but not limited to, forsterite and Mg 2 SiO 4 . The garnets include ground silicate minerals such as, but not limited to, pyrope; Mg 3 Al 2 Si 3 O 12 ; grossular; and Ca 2 Al 2 Si 3 O 12 . The aluminosilicates include ground silicate minerals such as, but not limited to, sillimanite; Al 2 SiO 5 ; mullite; 3Al 2 O 3 .2SiO 2 ; kyanite; and Al 2 SiO 5 . The ring silicates can be used as extender fillers and these include silicate minerals such as, but not limited to, cordierite and Al 3 (Mg,Fe) 2 [Si 4 AlO 18 . The chain silicates include ground silicate minerals such as, but not limited to, wollastonite and Ca[SiO 3 . The sheet silicates can alternatively or in addition be used as extender fillers, where suitable classes include silicate minerals such as, but not limited to, mica; K 2 AI14 [Si 6 Al 2 O 20 (OH) 4 ; Pyrophyllite; Al 4 [Si 8 O 20 (OH) 4 ; Talc; Mg 6 [Si 8 O 20 (OH) 4 ; Serpentine, such as asbestos; Kaolinite; Al 4 [Si 4 O 10 (OH) 8 ; And Vermiculite.

[0193] Tackifier

[0194] The composition may further comprise one or more tackifiers selected from: one or more monoacrylates, diacrylates or methacrylates; alkoxysilanes containing epoxy groups, alkoxysilanes containing amine groups, alkoxysilanes containing methacrylic acid groups or acrylic acid groups, and mixtures and / or reaction products of the following substances:

[0195] i) one or more alkoxysilanes having epoxy groups in the molecule;

[0196] ii) linear organopolysiloxane oligomers containing at least one alkenyl group and at least one hydroxyl or alkoxy group per molecule; and

[0197] iii) organometallic condensation reaction catalysts including organoaluminum or organozirconium compounds; or mixtures thereof;

[0198] Rheology modifier

[0199] The composition may further comprise a rheology modifier such as polytetrafluoroethylene (PTFE).

[0200] Pigment and other colorants

[0201] Examples of pigments include titanium dioxide, chromium(III) oxide, bismuth vanadium oxide, iron oxide, and mixtures thereof.

[0202] Examples of colorants useful in the organosilicon coating compositions curable by hydrosilylation include pigments, vat dyes, reactive dyes, acid dyes, chrome dyes, disperse dyes, cationic dyes, and mixtures thereof. The two-part moisture-curable organopolysiloxane compositions as described herein may also contain one or more pigments and / or colorants, which may be added if desired. The pigments and / or colorants may be colored, white, black, metallic effect, and luminescent, such as fluorescent and phosphorescent. Pigments are used as needed to color the composition. Any suitable pigments that provide compatibility with the compositions herein may be utilized. In the two-part 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 final sealant product.

[0203] Suitable white pigments and / or colorants include titanium dioxide, zinc oxide, lead oxide, zinc sulfide, lithopone, zirconium oxide, and antimony oxide.

[0204] Suitable non-white inorganic pigments and / or colorants include, but are not limited to, iron oxide pigments such as goethite, lepidocrocite, hematite, maghemite, and magnetite black iron oxides, yellow iron oxides, brown iron oxides, and red iron oxides; blue iron pigments; chromium oxide pigments; cadmium pigments such as cadmium yellow, cadmium red, and cadmium vermilion; bismuth pigments such as bismuth vanadate and bismuth molybdovanadate; 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 antimonate titanate; lead chromate; carbon black; lampblack; and metallic effect pigments such as aluminum, copper, copper oxide, bronze, stainless steel, nickel, zinc, and brass.

[0205] Suitable organic non-white pigments and / or colorants include phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; monoarylide yellows, diarylide yellows, benzimidazolone yellows, heterocyclic yellows, 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 condensation pigments, isoindolinone and isoindoline pigments, polycyclic pigments, perylene and violanthrone pigments, thioindigo pigments, anthrapyrimidine pigments, flavanthrone pigments, anthraquinone pigments, dioxazine pigments, triarylmethonium pigments, quinophthalone pigments, and diketopyrrolopyrrole pigments.

[0206] Generally, pigments and / or colorants, when particulate, have an average particle size in the range of 10 nm to 50 μm, preferably in the range of 40 nm to 2 μm.

[0207] Lubricant

[0208] Typically, if present, lubricants that can be added to the compound composition include polyphenylmethylsiloxane and its copolymers, such as trimethylsilyl-terminated phenylmethylsiloxane dimethylsiloxane copolymer, which has a viscosity of 100 mPa·s to 200 mPa·s at 25 °C, and this viscosity is measured using a Brookfield Tm rotational viscometer with a cone-plate arrangement having a cone CP-52 at 12 rpm, and mixtures or derivatives thereof. Examples of other lubricants that can be used alternatively or additionally include tetrafluoroethylene, resin powder, graphite, fluorinated graphite, talc, boron nitride, fluorinated oil, molybdenum disulfide, and mixtures or derivatives thereof. When present, such lubricants can be present in an amount of 1 wt% to 7 wt% of the composition.

[0209] Heat stabilizer

[0210] The compositions herein may also contain 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 alumina, red iron oxide, yellow iron oxide, carbon black, graphite, and zinc oxide.

[0211] Metal deactivator

[0212] The composition may incorporate one or more metal deactivators selected from diacylhydrazine-based compounds, aminotriazole-based compounds, and aminotriazine-containing compounds. Commercially produced compounds of the above include, for example, N,N'-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, which is sold by BASF under the name Irganox Tm MD1024, dodecanedioyl-bis-(N'-salicyl)hydrazine, the synonym of which is 1-N',12-N'-bis(2-hydroxybenzoyl)dodecanedioylhydrazine, which is commercially sold as ADK STAB Tm CDA-6 from Adeka Corporation; N'1,N'12-bis(2-hydroxybenzoyl)dodecanedioylhydrazine, which is commercially sold as ADK STAB TM CDA-6S from Adeka Corporation; and N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, which is sold as ADK STAB TMCDA-10 is commercially available from Adeka Corporation; and N,N'-bis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionylhexamethylenediamine, which is commercially available as ANTAGE HP-300 from Kawaguchi Chemical Industry. Examples of such commercially produced compounds they may also include are 3-(n-salicyl)amino-1,2,4-triazole (the synonym of which is 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide), which is available as ADK STAB Tm CDA-1 and in blend form as ADK STAB Tm CDA-1M is commercially available from Adeka Corporation or as Adekastab Tm ZS-27 is commercially available from Adeka Corporation, and its main component is understood to be 2,4,6-triamino-1,3,5-triazine.

[0213] Before use, the selected organocyclosiloxane oligomer is stored in a suitable storage container or supplied directly from the manufacture. If the selected organocyclosiloxane oligomer that is stored directly at the time of manufacture for immediate use is supplied to a storage container, or stored in said storage container for immediate use, or if the selected organocyclosiloxane. If desired, any of the above optional additives can be introduced into the matrix, but this is generally not done. They are typically introduced into the matrix together with a catalyst during the compounding process and, in the case of a hydrosilylation curing crosslinker, into the matrix. No catalyst and crosslinker are added during the preparation of the matrix herein.

[0214] In one embodiment, if desired, after step (iv) or (v), the resulting step (iv) or step (v) product can be granulated or dusted with a suitable powder before storage.

[0215] In another embodiment, the method for preparing an uncatalyzed (fluoro)organosiloxane rubber matrix forms part of a continuous compounding method. Examples

[0216] The following are a series of examples.

[0217] In each of Ex.1 and Comparative Examples 1 to 3 (Comp.1 to Comp.3), an attempt was made to prepare a series of uncatalyzed fluoroorganosiloxane rubber matrices. In Ex.1, Colmec was used TMThe CTM-65 mixer, as a conical screw tablet press, prepares a fluorinated organosilicon rubber matrix according to the method for preparing an uncatalyzed (fluorinated) organosilicon rubber matrix described herein. A dimethylhydroxy-terminated polytrifluoropropylmethylmethylvinylsiloxane gum having a Williams plasticity of about 278 mm / 100 and a vinyl content of 0.188 wt% according to ASTM D-926-08 is combined with 2 wt% to 5 wt% of a small amount of processing aid in the form of a vinyl-terminated poly(dimethylsiloxane-co-methylvinylsiloxane) having a viscosity of 370 mPa·s at 25 °C and introduced into Colmec TM CTM-65 mixer, and this viscosity is measured at 12 rpm using a Brookfield TM rotational viscometer with a cone-plate arrangement with cone CP-52.

[0218] The above substances are stirred while gradually introducing 40 wt% of untreated pyrogenic silica (available as CAB-O-SIL TM MS-75D commercially available from Cabot Corporation) and about 4 wt% of a filler treatment agent into the Colmec TM CTM-65 mixer and mixing into the gum at a speed of about 45 rpm - 60 rpm. This filler treatment agent contains a short-chain dimethylhydroxy-terminated polytrifluoropropylmethylsiloxane having an average DP of 5 to 15. Once the silica is introduced, the mixing is carried out in a nitrogen atmosphere. The components are introduced at about 25 °C, but the action of shear mixing gradually raises the temperature inside the mixer to the range of 50 °C to 80 °C. Once the components are satisfactorily mixed with each other, no heating step is carried out, and the base product is held at 150 °C at about 15 rpm for about 60 minutes to ensure the removal of volatiles generated by the in-situ treatment of the filler surface to make it hydrophobic and form a fluorinated organosilicon rubber matrix material.

[0219] Subsequently, the fluorinated organosilicon matrix is extruded from the Colmec TM CTM-65 mixer and cooled to a temperature below 90 °C.

[0220] Then the resulting fluorinated organosilicon rubber matrix is mixed with additional fluorinated organosilicone gum in a sigma blade mixer, thereby reducing or cutting the filler content from 40 wt% to 20 wt%. Then the change in plasticity over time of a sample of the resulting matrix containing 20 wt% reinforcing filler is tested, and the results are provided in Table 1 below. Comp.1 and Comp.2 were also prepared from the beginning with only 20 wt% of the reinforcing filler, so there was no reduction or cutting step.

[0221] Comp.1 follows exactly the same method as described in Ex.1, except that Colmec is introduced. TM The amount of filler in the CTM-65 mixer is 20 wt%, so no reduction or trimming step is required.

[0222] In comp.2, the same ingredients and amounts as used for comp.1 are used to prepare the matrix and the subsequent compound, but in this case, a Sigma blade mixer is used for mixing.

[0223] Then the plastic properties of these are compared with Ex.1.

[0224] Subsequently, 1.2 parts per hundred (pph) of benzoyl peroxide dichloride is introduced into the uncatalyzed fluorosilicone rubber matrix to make it curable by milling on a two-roll mill, and the curing physical properties of the resulting cured elastomeric material are evaluated. Again, the results are provided in Table 1, where comparison is made with the cured elastomeric materials of comp.1 and Comp.2. Comp.3 is also prepared, where an attempt is made to introduce 40 wt% filler into the rubber using a Sigma blade mixer, so comp.3 is an attempt to repeat Ex.1 using a Sigma blade mixer. However, it is proven impossible to prepare a continuous matrix containing 40 wt% filler in this mixer. Some of the filler will not incorporate, and the bulk of the matrix is "friable" and cannot be made into a satisfactory continuous mass. Therefore, it is considered impossible to test the physical properties of comp.3, and thus this comparative example is omitted from Table 1 below.

[0225] Table 1. Comparison of the properties of Ex.1, Comp.1 and Comp.2

[0226] Ex.1 Comp.1 Comp.2 Plasticity after 1 hour (mm / 100) 220 283 277 Plasticity after aging at room temperature for 7 days (mm / 100) 232 297 287 Plasticity after 4 days at 70 °C (mm / 100) 248 307 292 Elongation at break (%) 475 430 423 Elongation at break after curing (%) 451 439 399 Tear strength (kN / m) 24.1 21.5 15.4

[0227] All plastic results are timed starting from when the matrix is freshly milled on a two-roll mill after extrusion from the mixer and reaching 25 °C in the case of Ex.1, and starting from when preparation and fresh milling are completed and reaching 25 °C for comp.1 and Comp.2, and are measured according to ASTM D-926-08. The elongation at break is measured according to ASTM D412, and the post-cured samples are post-cured at a temperature of 200 °C for 4 hours. The tear strength results are measured using Die B according to ASTM D624.

[0228] It can be seen that the results of Ex.1 obtained using the matrix prepared as described herein give lower plastic results than comp.1 and comp.2, indicating that the matrix prepared by the method herein is more easily handled by the users of this matrix during compounding. It will also be noted that the matrix prepared using a conical screw tablet press shows improvement over the matrix prepared using a Sigma blade type mixer.

[0229] The above plastic results seem to be consistent with the physical property results in Table 1, because the best results were obtained using the method described herein, while the worst results were obtained using a sigma blade mixer. It should be understood that Ex.1 has a more effective matrix preparation method because it can integrate a larger amount of filler into the continuous matrix, making this method more effective than the sigma blade method, which would require significantly more energy to mix the filler into the gum due to the presence of a larger amount of gum.

[0230] Another series of examples and comparative examples (Ex.2 and Comp.4 to Comp.7) were prepared using a dimethyl vinyl terminated polydimethylsiloxane gum (i.e., non-fluorinated).

[0231] In each of Ex.2 and Comp.4 to Comp.7), an attempt was made to prepare a series of uncatalyzed silicone rubber matrices. In Ex.2, a Colmec TM CTM-65 mixer was used as a conical screw press to prepare the silicone rubber matrix according to the method described herein. A dimethyl vinyl terminated polydimethylsiloxane gum with a Williams plasticity of about 148 mm / 100 and a vinyl content of 0.012% according to ASTM D-926-08 was combined with 2 wt% to 5 wt% of a small amount of processing aid in the form of a vinyl terminated poly(dimethylsiloxane-co-methylvinylsiloxane) having a viscosity of 370 mPa·s at 25 °C and introduced into the Colmec TM CTM-65 mixer, and this viscosity was measured at 12 rpm using a Brookfield TM rotational viscometer with a cone plate arrangement having a cone CP-52.

[0232] The above substances were stirred while gradually introducing 40 wt% of untreated pyrogenic silica (available commercially as CAB-O-SIL TM MS-75D from Cabot Corporation) and about 4 wt% of a filler treatment agent into the Colmec TMIn the CTM-65 mixer, it is mixed into the glue at a speed of about 45 rpm - 60 rpm. The filler treatment agent contains short-chain dimethyl hydroxy-terminated polydimethylsiloxane with an average DP of 5 to 15. Once all the silica is introduced, the mixing is carried out in a nitrogen atmosphere. The components are introduced at about 25 °C, but the action of shear mixing gradually raises the temperature inside the mixer to the range of 50 °C to 80 °C. Once the components are satisfactorily mixed with each other, no heating step is carried out, and the base product is held at about 150 °C at a speed of about 15 rpm for about 60 minutes to ensure the removal of volatiles generated by the in-situ treatment of the filler surface, to make it hydrophobic and form an uncatalyzed silicone rubber matrix.

[0233] Subsequently, the silicone rubber matrix is extruded from the Colmec TM CTM-65 mixer and cooled to a temperature below 90 °C.

[0234] Then the obtained silicone rubber matrix of Ex.2 is mixed with additional dimethyl vinyl-terminated polydimethylsiloxane glue as described above in a sigma blade mixer. During mixing, sufficient dimethyl vinyl-terminated polydimethylsiloxane glue is added thereto to reduce or cut the filler content from 40 wt% of the matrix to 20 wt%. Then the change of plasticity of the obtained sample of the matrix containing 20 wt% reinforcing filler with time is tested, and the results are provided in Table 2 below.

[0235] Comp.4 follows exactly the same method as described for Ex.2, except that the amount of filler introduced into the Colmec TM CTM-65 mixer is 20 wt%, so no reduction or cutting step is required. In Comp.5, the same components and amounts as those used for Comp.4 are used to prepare the matrix and the subsequent compound composition, but in this case, a sigma blade mixer is used for matrix preparation. Comp.6 and Comp.7 are prepared using the same components as Ex.2, where an attempt is made to introduce 40 wt% of the filler into the silicone rubber stock using a sigma blade mixer (Comp.6) and a compression type sigma blade mixer (Comp.7).

[0236] Subsequently, 1.2 parts per hundred parts (pph) of benzoyl peroxide dichloride is introduced into the uncatalyzed silicone rubber matrix to make it curable by milling on a two-roll mill, and then the obtained compound composition is cured at 250 °F (about 121 °C) for a period of 5 minutes. Several physical properties of the obtained cured elastomeric material are evaluated. Similarly, the results are provided in Table 2, where a comparison is made with the cured elastomers produced from the preparation of the elastomeric materials of Comp.4 and Comp.5.

[0237] It was found that in the case of Comp.6, similar to Comp.3, the matrix would agglomerate discontinuously. It fragmented and did not re - aggregate. Further, repeating Comp.6 but using a compression - type sigma blade mixer (Comp.7), it was seen that when using 40 wt% filler, despite additional compression using a fixed plate that reduced the free volume in the mixer to <50% of its original volume, thus generating a downward compressive force on the matrix equal to the upward force from the mixing blades; that is, adding a compression plate to the sigma blade device did not result in a significant improvement regarding agglomeration. Thus, Comp.6 and Comp.7 could not be reduced (trimmed) or cured, and thus their physical properties were not tested.

[0238] The plastic results of the matrix and the physical property results of the resulting elastomers are described in Table 2 below relative to Ex.2 and Comp.6 and Comp.7.

[0239] Table 2

[0240] Ex.2 Comp.4 Comp.5 Plasticity after 1 hour (mm / 100) 157 170 178 Plasticity after aging at room temperature for 7 days (mm / 100) 185 189 215 Plasticity after 4 days at 70 °C (mm / 100) 216 218 253 Elongation at break (%) 632 620 625 Elongation at break after curing (%) 560 544 492 Tear strength (kN / m) 27.3 23.5 21.1

[0241] The test methods used were exactly the same as the results in Table 1 above.

[0242] It can be seen that the results of Ex.2 obtained using the matrix prepared as described herein gave lower plastic results than Comp.4 and Comp.5, indicating that the matrix prepared by the method herein was more easily processed by the users of the matrix during compounding. It will also be noted that the matrix prepared using a conical screw tablet press showed improvement compared to the matrix prepared using a sigma blade - type mixer.

[0243] The above - mentioned plastic results seem to be consistent with the physical property results in Table 1, as the best results were obtained using the method described herein, while the worst results were obtained using a sigma blade - type mixer. It should be understood that Ex.1 has a more efficient matrix preparation method because it can integrate a larger amount of filler into a continuous matrix, making the method more efficient than the sigma blade method, which would require significantly more energy to mix the filler into the rubber due to the presence of a larger amount of rubber.

[0244] In another series of embodiments, the ability to introduce the non - reinforcing filler aluminum trihydrate was evaluated to compare saturation levels, and the non - reinforcing filler aluminum trihydrate is typically included as a flame retardant and smoke suppressant non - reinforcing filler in silicone elastomers.

[0245] In Ex.3, Colmec was used TMThe CTM-65 mixer was used to perform exactly the same method as in Ex. 2 to prepare the uncatalyzed matrix, except that an alternative silicone gum was used. The silicone gum was a vinyl dimethyl terminated polyvinyl methyl dimethyl siloxane copolymer having a Williams plasticity of 149.6 mm / 100 and a vinyl content of 0.0654 wt%. Additionally, in Ex. 3, no processing aids were used in combination with the gum and no catalyst was added as only the uncatalyzed matrix was prepared. After performing the reduction / cutting step to add more gum such that the matrix contained only 20 wt% of reinforcing silica filler, aluminum trihydrate was gradually introduced into the Ex. 3 matrix until a saturation level of 170 pph of aluminum trihydrate had been added to the matrix (total composition of 61.5 wt% gum + reinforcing filler + treatment agent + aluminum trihydrate). Two additional comparative examples, Comp. 8 and Comp. 9, were prepared. In Comp. 8, a silicone rubber matrix containing 20 wt% silica filler was prepared without performing the reduction / cutting step. This matrix also had aluminum trihydrate gradually introduced until a saturation level of 150 pph was introduced, after which the matrix began to crumble. Thus, the matrix in Ex. 3 was shown to be able to accommodate a significantly greater amount of aluminum trihydrate than Comp. 8 could accommodate. In the case of Comp. 9, the matrix was prepared in exactly the same manner as Comp. 8, the only difference being that a Sigma blade mixer was used to prepare the matrix containing 20 wt% silica reinforcing filler. In the case of Comp. 9, once the matrix containing 20 wt% silica reinforcing filler was prepared, aluminum trihydrate was gradually introduced until a saturation level of only 50 pph was introduced, after which the matrix began to crumble.

[0246] Therefore, it should be understood that a silicone rubber matrix having a reinforcing filler content of 20 wt% (the content of which was reduced from at least 40 wt% using a conical screw tablet press with a reduction / cutting step) is surprisingly able to accommodate a significantly greater amount of aluminum trihydrate before reaching saturation compared to a matrix having a reinforcing filler content of 20 wt% prepared without a reduction / cutting step or especially a matrix having a reinforcing filler content of 20 wt% prepared in a Sigma blade mixer without a reduction / cutting step.

[0247] In Ex. 4 and Ex. 5, a base composition prepared using 45 wt% of starting component (b) was first prepared. Ex. 4 was reduced to a matrix containing 38.5 wt% of reinforcing filler, and Ex. 5 was reduced to a matrix containing 32 wt% of reinforcing filler. A dimethylvinyl-terminated polydimethylsiloxane gum with a Williams plasticity of 148 mm / 100 and a vinyl content of 0.012% according to ASTM D-926-08 was combined with 2 wt% to 5 wt% of a small amount of processing aid in the form of a vinyl-terminated poly(dimethylsiloxane-co-methylvinylsiloxane) having a viscosity of 370 mPa·s at 25 °C and introduced into a Colmec TM CTM-65 mixer, and this viscosity was measured at 12 rpm using a Brookfield TM rotational viscometer with a cone-plate arrangement having a cone CP-52.

[0248] The above substances were stirred while gradually introducing the 45 wt% of untreated pyrogenic silica (available commercially as CAB-O-SIL TM MS-75D from Cabot Corporation) and approximately 4 wt% of a filler treatment agent into the Colmec TM CTM-65 mixer and mixing into the gum at a speed of approximately 45 rpm - 60 rpm. The filler treatment agent comprised short-chain dimethylhydroxy-terminated polydimethylsiloxane having an average DP of 5 to 15. Once all the silica was introduced, mixing was carried out in a nitrogen atmosphere. The components were introduced at approximately 25 °C, but the action of shear mixing gradually raised the temperature inside the mixer to within the range of 50 °C to 80 °C. Once the components were satisfactorily mixed with each other, no heating step was carried out, and the base product was held at 150 °C at approximately 15 rpm for approximately 60 minutes to ensure removal of volatiles generated by in-situ treatment of the filler surface to render it hydrophobic and form an uncatalyzed silicone rubber matrix.

[0249] Subsequently, before extrusion from the Colmec TM CTM-65 mixer, the silicone rubber matrix was cooled to below 60 °C in this mixer. In this case, the extruded silicone rubber matrix was actually returned to the Colmec TM CTM-65 mixer for step (v), for reduction / cutting. In Ex. 4, a sufficient amount of dimethylvinyl-terminated polydimethylsiloxane gum with 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 TM CTM-65 mixer such that a final matrix product having a total of 38.5 wt% of reinforcing filler was obtained after step (v).

[0250] In Example 5, the exact same method was carried out, except that more glue was introduced in step (v) such that a final matrix product with a total of 32.0 wt% of reinforcing filler was obtained.

[0251] In each of Ex. 4 and Ex. 5, the compound was prepared according to step (vi) herein. Thus, 1.2 parts per hundred parts (pph) of benzoyl peroxide dichloride was introduced into the uncatalyzed silicone rubber matrix to make it curable by milling on a two-roll mill, and then the resulting compound composition was cured at 250°F (about 121°C) for a period of 5 minutes to prepare the respective resulting samples. In this case, some samples of both Ex. 4 and Ex. 5 were post-cured at a temperature of 200°C for 4 hours.

[0252] The physical properties of the resulting cured silicone elastomers were evaluated and the results are provided in Table 3 below. The physical properties of samples of the original matrix material with 45 wt% of reinforcing filler having a peroxide catalyst milled in the same manner (Ref. 1) were also evaluated. The same test methods as described above were used.

[0253] Table 3

[0254] Ref.1 Ex.4 Ex.5 Shore A hardness Elongation at break (%) 53.9 45.3 32.8 Elongation at break (%) 218 281 349 Elongation at break after curing (%) 162 261 320 Modulus at 100% elongation (MPa) 5.18 2.99 1.89

[0255] These results show that a high-viscosity matrix incorporating a high level of silica filler can be prepared and then its filler content can be reduced or trimmed to other lesser filler loadings, thereby successfully preparing a matrix with an acceptable range of properties at each loading.

Claims

1. A method for preparing an uncatalyzed (fluoro)organosilicon rubber matrix, the uncatalyzed (fluoro)organosilicon rubber matrix being prepared by introducing reinforcing fillers and optionally a hydrophobic treatment agent into one or more organosilicon polymers, fluoroorganosilicon polymers, or copolymers thereof, in each case the one or more organosilicon polymers, fluoroorganosilicon polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, the method comprising the steps of: (i) introducing the one or more organosilicon polymers, fluoroorganosilicon polymers, or copolymers thereof, as a first starting component, into the mixing chamber of a mixer at about 25 °C, optionally in an inert atmosphere, and mixing, the one or more organosilicon polymers, fluoroorganosilicon polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 in each case according to ASTM D-926-08; (ii) gradually introducing one or more reinforcing fillers, as a second starting component, and optionally a third starting component, one or more hydrophobic filler treatment agents, into the mixing chamber of the mixer while continuing to mix until the mixer has been charged with a predetermined amount of reinforcing filler of at least 38 wt% of the total basic starting components to form a basic mixture; (iii) optionally maintaining the temperature of the basic mixture in the mixing chamber within a predetermined range of 100 °C to 200 °C for a period of up to 6 hours to remove volatiles from the basic mixture of step (ii) to form the basic mixture of step (iii), wherein step (iii) can be carried out under vacuum when in use; (iv) cooling the resulting basic mixture of step (ii) or step (iii) to a temperature of 25 °C to 120 °C; and before, during, or after step (iv); (v) reducing the weight percentage of the reinforcing filler in the basic mixture of step (ii) or step (iii) to a predetermined amount by mixing the basic mixture of step (ii) or step (iii) with one or more additional organosilicon polymers, fluoroorganosilicon polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08 to form an uncatalyzed (fluoro)organosilicon rubber matrix; It is characterized in that the mixer used at least for steps (i), (ii) and (iii) is a conical screw tablet press including a conical twin-screw mixing chamber, the conical twin-screw mixing chamber accommodating two counter-rotating conical screws, the conical screws converging towards an extrusion die head having an inlet and an outlet, wherein the passage through the extrusion die head is controlled by a blocking device such that the outlet of the extrusion die head is adapted to be closed by the blocking device until the product of step (iii), (iv) or (v) is to be extruded from the conical screw tablet press and is opened after step (iii), (iv) or (v) if or when the uncatalyzed (fluoro) silicone rubber matrix is to be further processed or stored outside the conical screw tablet press, so that during mixing, the base mixture is driven towards the extrusion die head by a pair of counter-rotating conical screws and then forced to return when the extrusion die head is closed by the blocking device and then opened after step (iii), (iv) or (v) to allow the product of step (iii), (iv) or (v) to be extruded through the extrusion die head for further processing and / or storage.

2. The method according to claim 1, wherein the base mixture of step (ii) and the product of step (iv) contain 39% to 55% by weight of a reinforcing filler.

3. The method according to claim 1 or 2, wherein the silicone polymer, fluoro silicone polymer or copolymer thereof having a Williams plasticity of at least 100 mm / 100 in each case according to ASTM D-926-08 is selected from dialkyl alkenyl-terminated polydimethylsiloxane; dialkyl alkenyl-terminated dimethyl methylphenylsiloxane; trialkyl-terminated dimethyl methylvinyl polysiloxane; dialkyl vinyl-terminated dimethyl methylvinyl polysiloxane copolymer; dialkyl vinyl-terminated methylphenyl polysiloxane, dialkyl alkenyl-terminated methyl vinyl methylphenylsiloxane; dialkyl alkenyl-terminated methyl vinyl diphenylsiloxane; dialkyl alkenyl-terminated methyl vinyl methylphenyl dimethylsiloxane; trimethyl-terminated methyl vinyl methylphenylsiloxane; trimethyl-terminated methyl vinyl diphenylsiloxane; or trimethyl-terminated methyl vinyl methylphenyl dimethylsiloxane.

4. The method according to claim 1 or 2, wherein the silicone polymer, fluoro silicone polymer or copolymer thereof having a Williams plasticity of at least 100 mm / 100 in each case according to ASTM D-926-08 is selected from trimethyl-terminated polymethyltrifluoropropylsiloxane, dimethyl alkenyl-terminated polymethyltrifluoropropylsiloxane, dimethylsilanol-terminated polymethyltrifluoropropylsiloxane, trimethyl-terminated polymethylperfluoropropylsiloxane, dimethyl alkenyl-terminated polymethylperfluoropropylsiloxane or dimethylsilanol-terminated polymethyltrifluoropropylsiloxane.

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

6. The method according to any one of the preceding claims, the method comprising step (v).

7. The method according to any one of the preceding claims, wherein during step (i) and / or step (v) of the method, 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 at 25 °C of from 10,000 mPa·s to 500,000 mPa·s at 25 °C is introduced until the cumulative total of the total base starting components is 10% by weight.

8. The method according to any one of the preceding claims, wherein in step (v), the weight percentage of the reinforcing filler in the uncatalyzed (fluoro)silicone rubber matrix is reduced to an amount of 15% to 30% by weight based on the weight percentage of the total base starting components by mixing the product of step (iv) 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 the step (v) product.

9. The method according to any one of the preceding claims, wherein the cooling step (iv) of the (fluoro)silicone rubber matrix manufacturing method is carried out; (I) entirely in the conical screw extruder for preparing the uncatalyzed (fluoro)silicone rubber matrix, in which case the resulting uncatalyzed (fluoro)silicone rubber matrix is cold extruded at a temperature in the range of 30 °C to 40 °C; (II) partially in the conical screw extruder for preparing the uncatalyzed (fluoro)silicone rubber matrix, in which case the resulting uncatalyzed (fluoro)silicone rubber matrix is extruded at a medium temperature in the range of 50 °C to 80 °C and then transferred to an alternative device for further cooling; or (III) entirely outside the conical screw extruder for preparing the uncatalyzed (fluoro)silicone rubber matrix, in which case the resulting uncatalyzed (fluoro)silicone rubber matrix 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 device for cooling.

10. The method according to claim 9, wherein the cooling outside the conical screw extruder is carried out in a second "cooling" conical screw extruder, tray or other container which allows the conical screw extruder for preparing the uncatalyzed (fluoro)silicone rubber matrix to be reused for preparing another batch of uncatalyzed (fluoro)silicone rubber matrix.

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

12. The method according to any one of claims 1 to 10, wherein the method for preparing the uncatalyzed (fluoro)organosiloxane rubber matrix forms part of a continuous compounding method.

13. The method according to claim 6, wherein there is an additional step (vi) occurring simultaneously with or after step (v), step (v) being after step (iv), and wherein step (vi) comprises introducing at least one catalyst or vulcanizing agent and optionally one or more additives at a temperature of 25 °C to 60 °C to provide a catalyzed (fluoro)organosiloxane rubber compound, the one or more additives being selected from crosslinking agents, cure inhibitors, additional fillers, pigments, property modifiers, and the like.

14. An uncatalyzed (fluoro)organosiloxane rubber matrix, and / or a catalyzed (fluoro)organosiloxane rubber compound, the uncatalyzed (fluoro)organosiloxane rubber matrix being the product of the method according to any one of claims 1 to 10, the catalyzed (fluoro)organosiloxane rubber compound being the product of the method according to claim 11.

15. An uncatalyzed (fluoro)organosiloxane rubber matrix, the uncatalyzed (fluoro)organosiloxane rubber matrix being obtainable or obtained by the method according to any one of claims 1 to 10.

16. Use of a conical screw tablet press comprising a conical twin-screw mixing chamber accommodating two counter-rotating conical screws that converge towards an extrusion die head having an inlet and an outlet, wherein the passage through the extrusion die head is controlled by a shut-off device such that the outlet of the extrusion die head is adapted to be closed by the shut-off device in a method for preparing an uncatalyzed (fluoro)organosiloxane rubber matrix by introducing a reinforcing filler and optionally a hydrophobizing agent into one or more organosiloxane polymers, fluoroorganosiloxane polymers, or copolymers thereof, in each case the one or more organosiloxane polymers, fluoroorganosiloxane polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 according to ASTM D-926-08, the method comprising the steps of: (i) introducing the one or more organosiloxane polymers, fluoroorganosiloxane polymers, or copolymers thereof as a first starting component into the mixing chamber of a mixer at about 25 °C, optionally in an inert atmosphere, and mixing, the one or more organosiloxane polymers, fluoroorganosiloxane polymers, or copolymers thereof having a Williams plasticity of at least 100 mm / 100 in each case according to ASTM D-926-08; (ii) Gradually introduce one or more reinforcing fillers as the second starting component and optionally a third starting component, one or more hydrophobic filler treatment agents into the mixing chamber of the mixer while continuing mixing until the mixer is charged with a predetermined amount of reinforcing filler of at least 38% by weight of the total basic starting components to form a basic mixture; (iii) Optionally maintain the temperature of the basic mixture in the mixing chamber within a predetermined range of 100 °C to 200 °C for a period of up to 6 hours to remove volatiles from the basic mixture of step (ii), thereby forming the basic mixture of step (iii), which can be carried out under vacuum when in use; (iv) Cool the resulting basic mixture of step (ii) or step (iii) to a temperature of 25 °C to 120 °C; and before, during or after step (iv) (v) Reduce the weight percentage of the reinforcing filler in the basic mixture of step (ii) or step (iii) to a predetermined amount by mixing the basic mixture of step (ii) or 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 an uncatalyzed (fluoro)silicone rubber matrix; wherein during mixing, the basic mixture is driven towards the extrusion die head by a pair of counter-rotating conical screws, then forced to return when the extrusion die head is closed by the blocking device, and then opened after step (iii), (iv) or (v) to allow the respective product of step (iii), (iv) or (v) to be extruded through the extrusion die head for further processing and / or storage.