Silicone rubber composition

Abstract

This disclosure relates to a high-temperature vulcanizable (HTV) silicone rubber material cured from a curable high-temperature vulcanizable (HTV) silicone rubber composition having a high hardness (e.g., >30 Shore A hardness). The HTV silicone rubber composition comprises physically recycled and / or recovered silicone rubber microparticles obtained from cured silicone rubber elastomers having a Shore A hardness value of at least 30. The difference in Shore A hardness between the HTV silicone rubber material cured from the curable HTV silicone rubber composition containing the aforementioned physically recycled and / or recovered silicone rubber microparticles and the Shore A hardness of these cured silicone rubber elastomers from which the aforementioned silicone rubber microparticles are physically recycled and / or recovered is less than 30. This disclosure also relates to compositions and methods for preparing this material.

Description

[0001] This disclosure relates to a high-temperature vulcanizable (HTV) silicone rubber material cured from a curable high-temperature vulcanizable (HTV) silicone rubber composition having a high hardness (e.g., >30 Shore A hardness). The curable HTV silicone rubber composition comprises physically recycled and / or recovered silicone rubber microparticles obtained from cured silicone rubber elastomers having a Shore A hardness value of at least 30. The difference in Shore A hardness between the high-temperature vulcanizable (HTV) silicone rubber material cured from the curable HTV silicone rubber composition containing the aforementioned physically recycled and / or recovered silicone rubber microparticles and the Shore A hardness of these cured silicone rubber elastomers from which the aforementioned silicone rubber microparticles are physically recycled and / or recovered is less than 30. This disclosure also relates to the curable high-temperature vulcanizable (HTV) silicone rubber composition as defined above and methods for preparing said composition and the high-temperature vulcanizable (HTV) silicone rubber material. The Shore A hardness value was determined using ASTM D2240-15.

[0002] Silicone rubber compositions that can be cured by hydrosilylation (or addition) reaction are typically prepared by initially mixing polydiorganosiloxane polymers containing at least two alkenyl (or alkynyl) groups per molecule to prepare a silicone rubber matrix composition. These polydiorganosiloxane polymers may contain reinforcing and unreinforced inorganic or resin siloxane fillers and may be unfilled in some elastomer applications, such as gels or coatings for protecting electronic devices. HTV-curable silicone elastomers differ from condensation-curable or wet-curable (also known as room temperature vulcanization (RTV)) silicone elastomers in that the curing reaction that forms the crosslinked network does not produce leaving groups such as alcohols, ketoximes, or carboxylic acids. Examples of HTV-curable silicone elastomers include those that can be cured by hydrosilylation or by using a peroxide radical initiator. It should be understood that, in some cases, despite the name, HTV-curable materials can be cured at ambient or even sub-ambient conditions by appropriately selecting catalysts, stabilizers, and accelerators, and are therefore not limited to any specific temperature range for curing conditions.

[0003] Reinforced silica fillers are naturally hydrophilic when used, making them difficult to mix with polydiorganosiloxane polymers. Therefore, these fillers are typically pretreated with a treatment agent to make them hydrophobic, or alternatively, provided in a hydrophilic form. In the latter case, a hydrophobic treatment agent is typically (but not always) provided to treat the silica in situ during matrix mixing, i.e., the incorporation and dispersion of silica in the polymer is carried out in the presence of the treatment agent. The product of this mixing step is a silicone rubber matrix composition. This silicone rubber matrix composition can be provided in a form suitable for mixing with other components discussed below. Alternatively, the silicone rubber matrix composition can be in the form of a concentrate (commonly referred to in the industry as a “masterbatch” (MB)), which is typically diluted with another polydiorganosiloxane polymer before use. Various treatment agents can be used to make the filler hydrophobic. The treatment agent reacts with the OH groups on the surface of the silica filler, resulting in a reduction in the number of free OH groups on the silica, and thus making the silica surface increasingly hydrophobic.

[0004] Once the silicone rubber matrix composition has been prepared, organohydropolysiloxanes and hydrosilylation catalysts can be added to the matrix to provide a hydrosilylation-curable composition, or, in the case of a peroxide-curable formulation, they can be used to promote more efficient curing. However, commercial compositions are typically produced in multiple parts, usually in two parts, to prevent premature curing during storage before use. In such a two-part composition, one part (typically referred to as part A) comprises a pre-prepared matrix and a hydrosilylation catalyst, and the second part (typically referred to as part B) comprises a pre-prepared matrix and one or more organohydropolysiloxane crosslinking agents. Optionally, one or more curing inhibitors may be added to the part A composition, the part B composition, or both the part A and part B compositions. Preferably, both parts (A and B) are pumpable liquids, typically prepared using a pre-prepared matrix having a standard formulation having up to, for example, 30% silica and the remainder being predominantly a liquid polydiorganosiloxane containing at least two alkenyl groups per molecule.

[0005] Given that they are thermosetting materials, silicone elastomers cannot be melted and reprocessed into polymers suitable for their intended applications, and therefore it is difficult to provide effective recycling and / or recycling alternatives to incineration or landfill as end-of-life options to meet the increasingly desired “carbon footprint” reduction targets found in today’s manufacturing industry.

[0006] There are two main types of methods for recycling / recovering elastomer materials, which tend to be via "chemical processes," such as pyrolysis, chemical degradation, and chemical conversion, and via "physical processes," i.e., mechanical processes, such as mechanical recycling, thermomechanical recycling, and cryogenic mechanical recycling, as well as wet / solution milling methods. Given that the silicone elastomer is a thermosetting material, chemical recycling of silicone elastomers is not ideal because recycling / recovery requires significant separation and typically produces solid residues of low value. That is, physically recycled and / or recovered silicone elastomer particles are often incorporated as fillers in combination with binder materials used as an encapsulation matrix. The binder can be a novel silicone composition or an organic polymer material, which can also be combined with inorganic mixtures such as bitumen or cement mixtures, and serves to embed and / or encapsulate discrete particles. However, physically recycled and / or recovered silicone elastomer microparticles have not yet been considered suitable for high-value applications due to the inconsistency and variability of their properties, and therefore have a poor value proposition, with the microparticles being deployed only in lower-value applications, thus reducing the economic and technological incentives for reuse. This is because:

[0007] (i) Poor incorporation of silicone elastomer microparticles into the binder matrix;

[0008] (ii) Poor interfacial adhesion and bonding between silicone elastomer microparticles and the matrix can cause pre-formed silicone elastomer microparticles to act as defects in the matrix, thereby creating voids, surface protrusions or other heterogeneity in the matrix, resulting in inferior properties compared to new silicone elastomers.

[0009] A high-temperature vulcanizable silicone rubber material having a hardness greater than 30 Shore A as determined using an ASTM D2240-15 durometer is a cured product of the curable high-temperature vulcanizable (HTV) silicone rubber composition described herein, which provides a lower carbon footprint by being able to replace a large amount of new liquid silicone masterbatch (>10 wt.%) with physically recycled and / or recovered cured elastomer silicone microparticles.

[0010] A high-temperature vulcanizable silicone rubber material is provided, which has a Shore A hardness greater than 30 as determined by ASTM D2240-15. It is a cured product of a curable high-temperature vulcanizable (HTV) silicone rubber composition comprising...

[0011] a) An organopolysiloxane polymer having a zero-shear viscosity at 25°C between 100 mPa·s and 200,000 mPa·s (including the terminal value), and having at least two unsaturated groups per molecule selected from alkenyl and / or alkynyl groups, or

[0012] Organopolysiloxane polymer adhesive having Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured according to ASTM D926-08, and having at least two unsaturated groups per molecule selected from alkenyl groups, alkynyl groups, or mixtures thereof;

[0013] b) One or more fillers in an amount of 20.0% to 50% by weight of the composition;

[0014] (c) or (d), where

[0015] (c) is a free radical initiator; or

[0016] (d) is a hydrogenation silylation catalyst package, which contains...

[0017] (i) an organosilicon compound in an amount of 0.1% to 2% by weight of the composition, wherein each molecule of the organosilicon compound has an average of at least two or alternatively at least three Si-H groups; and

[0018] (ii) a hydrogenation silylation catalyst; and

[0019] e) Physically recycled and / or recovered cured silicone rubber microparticles (e)(i) having an average unswelled particle size of 1 mm or less, which have been infiltrated and swollen by an organopolysiloxane polymer swelling agent (e)(ii) having a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25 °C;

[0020] The physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are obtained from a cured silicone rubber elastomer having a Shore A hardness greater than 30 as determined using ASTM D2240-15, and

[0021] The difference in Shore A hardness between high-temperature vulcanized silicone rubber materials with a Shore A hardness greater than 30 and components (e)(i) cured silicone rubber elastomers from which they are physically recycled and / or recovered is less than or equal to 30 as determined using ASTM D2240-15.

[0022] A curable high-temperature vulcanizable (HTV) silicone rubber composition is also provided, the curable high-temperature vulcanizable (HTV) silicone rubber composition comprising

[0023] a) An organopolysiloxane polymer having a zero-shear viscosity at 25°C between 100 mPa·s and 200,000 mPa·s (including the terminal value), and having at least two unsaturated groups per molecule selected from alkenyl and / or alkynyl groups, or

[0024] Organopolysiloxane polymer adhesive having Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured according to ASTM D926-08, and having at least two unsaturated groups per molecule selected from alkenyl and / or alkynyl groups;

[0025] b) One or more fillers in an amount of 20.0% to 50% by weight of the composition;

[0026] (c) or (d), where

[0027] (c) is a free radical initiator; or

[0028] (d) is a hydrogenation silylation catalyst package, which contains...

[0029] (i) an organosilicon compound in an amount of 0.1% to 2% by weight of the composition, wherein each molecule of the organosilicon compound has an average of at least two or alternatively at least three Si-H groups; and

[0030] (ii) Hydrosilylation catalyst;

[0031] as well as

[0032] e) Physically recycled and / or recovered cured silicone rubber microparticles (e)(i) having an average unswelled particle size of 1 mm or less, which have been infiltrated and swollen by an organopolysiloxane polymer swelling agent (e)(ii) having a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25 °C;

[0033] in

[0034] (i) The physically recycled and / or recovered cured silicone rubber microparticles (e) (i) are obtained from a cured silicone rubber elastomer having a Shore A hardness value of at least 30 as determined using ASTM D2240-15;

[0035] (ii) The composition, upon curing, has a Shore A hardness greater than or equal to 30, as determined using ASTM D2240-15; and

[0036] The difference between the Shore A values ​​of (iii), (i), and (ii) is less than or equal to 30 as determined using ASTM D2240-15.

[0037] This article also provides a method for preparing high-temperature vulcanized silicone rubber materials, the method comprising the following steps:

[0038] (1) Physically recycled and / or recovered cured silicone rubber microparticles with an average unswelled particle size of 1 mm or less are obtained from cured silicone rubber elastomers having a Shore A hardness of at least 30 as determined by ASTM D2240-15.

[0039] (2) Mixing the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) from step (1) with an organopolysiloxane polymer swelling agent (e)(ii) having a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25°C for a defined period of time, so that the organopolysiloxane polymer swelling agent (e)(ii) can penetrate and swell the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) to form component (e);

[0040] (3) Forming the mixture of step (3), the mixture comprising at least a portion of components (a) and (e) and optionally one or more of components (b), (c) and / or (d); wherein

[0041] a) An organopolysiloxane polymer having a zero-shear viscosity at 25°C between 100 mPa·s and 200,000 mPa·s (including the terminal value), and having at least two unsaturated groups per molecule selected from alkenyl and / or alkynyl groups, or

[0042] Organopolysiloxane polymer adhesive having Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured according to ASTM D926-08, and having at least two unsaturated groups per molecule selected from alkenyl and / or alkynyl groups;

[0043] b) One or more fillers in an amount of 20.0% to 50% by weight of the composition;

[0044] (c) or (d), where

[0045] (c) is a free radical initiator; or

[0046] (d) is a hydrogenation silylation catalyst package, which contains...

[0047] (i) an organosilicon compound in an amount of 0.1% to 2% by weight of the composition, wherein each molecule of the organosilicon compound has an average of at least two or alternatively at least three Si-H groups; and

[0048] (ii) Hydrosilylation catalyst;

[0049] (4) Mix the mixture from step (3) with the remaining portions of components (a), (b), (c) and / or (d) to produce a curable, high-temperature vulcanizable (HTV) silicone rubber composition.

[0050] (5) Curing the curable high-temperature vulcanizable (HTV) silicone rubber composition at a temperature of 100°C to 200°C to form a high-temperature vulcanizable silicone rubber material having a Shore A hardness greater than 30 as determined using ASTM D2240-15.

[0051] The difference in Shore A hardness between high-temperature vulcanized silicone rubber materials with a Shore A hardness greater than 30 and components (e)(i) cured silicone rubber elastomers from which they are physically recycled and / or recovered is less than or equal to 30 as determined using ASTM D2240-15.

[0052] In one implementation, steps (2), (3), and optional step (4) may be performed together as a single step.

[0053] This article also provides a high-temperature vulcanized silicone rubber material, which is prepared according to the above method.

[0054] Also provided is the use of physically recycled and / or recovered cured silicone rubber microparticles (e)(i) with an average unswelled particle size of 1 mm or less in high-temperature vulcanized silicone rubber materials having a Shore A hardness greater than 30 as determined using ASTM D2240-15, wherein these physically recycled and / or recovered cured silicone rubber microparticles (e)(i) have been infiltrated and swollen by an organopolysiloxane polymer swelling agent (e)(ii) having a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25°C; and

[0055] The physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are obtained from a cured silicone rubber elastomer having a Shore A hardness value of at least 30 as determined using ASTM D2240-15;

[0056] This high-temperature vulcanizable silicone rubber material is a cured product of a curable high-temperature vulcanizable (HTV) silicone rubber composition, which in other respects includes

[0057] a) An organopolysiloxane polymer having a zero-shear viscosity at 25°C between 100 mPa·s and 200,000 mPa·s (including the terminal value), and having at least two unsaturated groups per molecule selected from alkenyl and / or alkynyl groups, or

[0058] Organopolysiloxane polymer adhesive having Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured according to ASTM D926-08, and having at least two unsaturated groups per molecule selected from alkenyl and / or alkynyl groups;

[0059] b) One or more fillers in an amount of 20.0% to 50% by weight of the composition;

[0060] (c) or (d), where

[0061] (c) is a free radical initiator; or

[0062] (d) is a hydrogenation silylation catalyst package, which contains...

[0063] (i) an organosilicon compound in an amount of 0.1% to 2% by weight of the composition, wherein each molecule of the organosilicon compound has an average of at least two or alternatively at least three Si-H groups; and

[0064] (ii) Hydrosilylation catalyst;

[0065] The difference in Shore A hardness between high-temperature vulcanized silicone rubber materials with a Shore A hardness greater than 30 and components (e)(i) of high-temperature vulcanized (HTV) silicone rubber elastomers obtained by physical recycling and / or recovery is less than or equal to 30 as determined using ASTM D2240-15.

[0066] High-temperature vulcanizable (HTV) silicone rubber compositions are compositions that can typically be cured at high temperatures between 100°C and 200°C. However, it should be noted that while most hydrogen silane curing processes are carried out within this temperature range, some hydrogen silane curing processes can be achieved at lower temperatures with selected components.

[0067] As used in this article, the terms recycling and recycling are intended to define the function of recovering waste and transforming it into new materials and usable products.

[0068] For the avoidance of ambiguity, the term average unswelled particle size is intended to refer to the average particle size of physically recycled and / or recovered cured silicone rubber particles (e)(i) as used herein, after the source of the physically recycled silicone elastomer particles (e)(i) and before mixing with a “swelling agent” that is otherwise identified as component (e)(ii) and / or organopolysiloxane polymer (e)(ii).

[0069] This provides a more sustainable curable high-temperature vulcanizable (HTV) silicone rubber composition, and subsequently, upon curing, yields a high-temperature vulcanizable silicone rubber material with a higher Shore A hardness (>30) as determined using ASTM D2240-15. This HTV silicone rubber material provides users with a lower carbon footprint by being able to replace a significant portion of the new liquid silicone composition (e.g., 10% by weight or more of the composition) with physically recycled and / or recovered HTV silicone rubber microparticles derived from / obtained from cured silicone rubber elastomers having a Shore A hardness value of at least 30 as determined using ASTM D2240-15. Furthermore, the difference in Shore A hardness between the HTV silicone rubber material with a Shore A hardness greater than 30 and component (e)(i) derived from its physically recycled and / or recovered cured silicone rubber elastomer is less than or equal to 30 as determined using ASTM D2240-15.

[0070] Therefore, this solution offers the benefit of reducing the carbon footprint associated with the production of new curable high-temperature vulcanizable (HTV) silicone rubber compositions, and providing a high-value alternative to incineration or landfill as a life-end option for silicone elastomers used to prepare physically recycled and / or recovered silicone elastomer microparticles.

[0071] The ability of the organopolysiloxane polymer swelling agent (e)(ii) described above to penetrate and swell physically recycled and / or recovered cured silicone rubber microparticles (e)(i) results in the formation of an interpenetrating network between the new silicone composition and the physically recycled and / or recovered silicone elastomer microparticles, leading to the presence of physically recycled and / or recovered silicone elastomers from different sources without significant degradation of the mechanical properties of the high-temperature vulcanizable silicone rubber material described herein (and possibly even “upgraded” through improved properties). This has a direct benefit to the life cycle assessment (LCA) of the composition by replacing the carbon dioxide equivalent (used in the preparation of components in curable high-temperature vulcanizable (HTV) silicone rubber compositions) with recycled material that does not require capital- and energy-intensive molecular-level purification steps (such as distillation).

[0072] Physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are obtained from cured silicone rubber elastomers having a Shore A hardness greater than 30 as determined using ASTM D2240-15.

[0073] Physically recycled and / or recovered cured silicone rubber microparticles (e)(i) obtained from cured silicone rubber elastomers having a Shore A hardness greater than 30 as determined using ASTM D2240-15 can originate from any suitable source, such as post-industrial waste or waste rubber, pre-consumer waste or waste rubber, or post-consumer waste or waste rubber, derived from, for example, silicone rubber elastomers prepared by hydrolyzable silanization curing compositions, peroxide curing compositions (by, for example, free radical curing processes using photoinitiators or photocatalysts, and UV curing compositions) exposed to UV light. These elastomers can be used in applications such as airbag coatings, gaskets and sealing adhesives, foams, molded rubber products, hoses and tubing (such as medical tubing), encapsulants, and potting compounds. The virgin elastomer and the resulting physically recycled and / or recovered silicone rubber microparticles can be dense or have inclusions or voids, as in foams.

[0074] Physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are used to prepare cured silicone rubber elastomers from which elastomeric silicone rubber materials are prepared by hydrogenated silanization curing, free radical curing, and / or photocuring.

[0075] When the source of the cured silicone rubber elastomer particles is a priori unknown, the cured rubber from which they originate, or the particles from physical recycling or recovery, can be characterized by a variety of known methods to determine the composition. These methods include spectroscopic techniques, such as infrared techniques, such as Fourier transform infrared (FTIR) spectroscopy, attenuated total reflectance infrared spectroscopy (ATR-IR), infrared microscopy, Raman spectroscopy, Raman microscopy, and solid-state nuclear magnetic resonance (NMR) spectroscopy; chemical derivatization and titration techniques; chemical digestion followed by chromatographic methods, such as gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), and liquid chromatography (LC); or by a variety of known elemental or ion analysis techniques, such as inductively coupled plasma optical emission spectrometry (ICP-OES), x-ray fluorescence (XRF), and neutron activation analysis (NAA).

[0076] Cured silicone rubber elastomers prepared from physically recycled and / or recovered cured silicone rubber microparticles (e)(i) have a Shore A hardness value of at least 30 as determined using ASTM D2240-15. Furthermore, the difference in Shore A hardness between high-temperature vulcanized silicone rubber materials having a Shore A hardness greater than 30 and those from physically recycled and / or recovered cured silicone rubber elastomers of component (e)(i) is less than or equal to 30 as determined using ASTM D2240-15.

[0077] Physical recycling methods are used to convert cured silicone rubber elastomers into powders, granules, chips, or pellets (collectively referred to herein as “microparticles”). For the avoidance of doubt, for the purposes of this disclosure, physically (mechanically) recycled / recovered microparticles retain their original cross-linked structure, whereas chemically recycled materials do not.

[0078] Cured silicone elastomer microparticles obtained through physical recycling and / or recovery (e)(i) are prepared by any suitable physical recycling method, such as by milling, grinding, or pulverizing methods, for example by mechanical recycling, thermomechanical recycling, cryogenic mechanical recycling, and wet / solution milling. Specific examples of methods that can be used to produce microparticles include, for example, cryogenic milling (at liquid nitrogen temperature), using milling equipment known in the art, such as ball mills, pin mills, etc., cyclone milling (which can be performed in a solid state at ambient or cryogenic temperatures), and wet jet milling (e.g., wet jet), in which the rubber is pulverized by a strong stream of water.

[0079] The physically recycled and / or recovered cured silicone elastomer microparticles (e)(i) have an average particle size of 1 mm or less. Smaller particle sizes are preferred to minimize stress concentration defects in virgin articles, but satisfactory performance has been achieved even for milled physically recycled and / or recovered cured silicone elastomer microparticles (e)(i) with a relatively larger 1 mm size. In one embodiment, the physically recycled and / or recovered cured silicone elastomer microparticles (e)(i) have an average particle size of 600 μm or less, alternatively pre-formed silicone elastomer microparticles have an average particle size of 500 μm or less, alternatively pre-formed silicone elastomer microparticles have an average particle size of 400 μm or less, alternatively pre-formed silicone elastomer microparticles have an average particle size of 300 μm or less, and alternatively pre-formed silicone elastomer microparticles have an average particle size of 200 μm or less. Particles of acceptable sizes can be obtained by mechanical sieving with a mesh size. Smaller particles are obtained by filtration with progressively smaller mesh sizes.

[0080] For more precise particle size measurement, laser diffraction can be used, employing, for example, a Beckman Coulter with a Tornado (dry) module, commercially available from Beckman Coulter Inc. ™ The LS13 320 particle size analyzer is dependent on the Beckman Coulter. ™ The software deconvolves the diffraction signal to obtain a particle size distribution determined using the Fraunhofer diffraction model to measure the sample.

[0081] If the silicone elastomers to be made into microparticles are adhered to another material before use, they are preferably separated or peeled off. For example, in the case of recyclable airbag articles, the first step is to recover the silicone elastomers by peeling them off the textile carrier. The resulting coating can then be broken down into microparticles using one of the methods listed above.

[0082] However, it should be understood that the peeling or separation of silicone materials from certain substrates or articles may be imperfect and may result in some residual trace amounts of foreign non-silicone contaminants, such as small fragments of fabric or plastic substrates, in the resulting particles, which may be present in amounts less than 10% by weight, preferably 5% by weight or less, of which less is desirable. Physical recycling and / or recovery using one or more of the different methods described above provides:

[0083] 1) The advantage of being able to reuse inorganic fillers,

[0084] 2) The ability to incorporate contaminated raw materials into silicone elastomers, and the ability to tolerate residual Si-H from hydrosilane-cured silicone elastomers that may produce process incompatibility or formulation instability, without having to undergo depolymerization, neutralization, filtration and stripping steps associated with chemical recycling processes.

[0085] Organopolysiloxane polysiloxanes with a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25°C Physical recycling of compound swelling agents (e)(ii) and / or infiltration and swelling of cured silicone rubber microparticles (e)(i) .

[0086] As discussed above, the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) in the cured high-temperature vulcanizable (HTV) silicone rubber compositions cured herein have an average unswelled particle size of 1 mm or less. However, the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are not simply directly mixed into standard cured high-temperature vulcanizable (HTV) silicone rubber compositions to encapsulate them during composition curing. They are initially immersed and / or soaked in a low-viscosity organopolysiloxane polymer having a zero-shear viscosity (e)(ii) of less than or equal to (≤) 15,000 mPa·s at 25°C, alternatively having a zero-shear viscosity (e)(ii) of 100 mPa·s to 13,000 mPa·s at 25°C, alternatively having a zero-shear viscosity (e)(ii) of 100 mPa·s to 10,000 mPa·s at 25°C, alternatively having a zero-shear viscosity (e)(ii) of 100 mPa·s to 7,500 mPa·s at 25°C, alternatively having a zero-shear viscosity (e)(ii) of 100 mPa·s to 5,000 mPa·s at 25°C, alternatively having a zero-shear viscosity (e)(ii) of 100 mPa·s to 2,000 mPa·s at 25°C. Examples of (e)(ii) include vinyl dimethyl-terminated divinyl-functionalized polydimethylsiloxanes, hydroxyl-terminated polydiorganosiloxanes, alkoxy-terminated polydiorganosiloxanes, or siloxane crosslinkers as defined herein as component (c), such as polymethylhydrodimethylsiloxane copolymers. They may also be non-reactive silicone plasticizers, such as trimethyl-terminated polydimethylsiloxanes. The organopolysiloxane polymer swelling agent (e)(ii) is present in the composition in an amount of about 1.0% by weight to 5.0% by weight.

[0087] Physically recycled and / or recovered cured silicone rubber microparticles (e)(i) may or may not react with organopolysiloxane polymers (e)(ii) having a zero shear viscosity of ≤15,000 mPa·s at 25°C, and similarly, may or may not react with components of the composition in which it will be located.

[0088] It has been found that a pre-cured phase containing physically recycled and / or recovered cured silicone rubber microparticles (e)(i) within a second curable network provides a means of forming a dual-network or interpenetrating network (IPN) having an organopolysiloxane polymer (e)(ii) with a zero-shear viscosity of ≤15,000 mPa·s at 25°C capable of penetrating and swelling the microparticles (e)(i). Unbound by currently held theories, it is believed that the microparticle component (e)(i) consists of a pre-cured cross-linked “mesh” component, and the composition in which component (e)(ii) forms a part also forms a cross-linked network. Due to the ability of component (e)(ii) to penetrate and swell component (e)(i), the two networks are physically entangled, resulting in physical bonding rather than mere encapsulation. It has been found that the lower the viscosity value of component (e)(ii), the greater the penetration and swelling of component (e)(i).

[0089] Furthermore, when component (e)(ii) has a zero-shear viscosity greater than 15,000 mPa·s at 25°C, penetration and swelling occur or occur at a minimal level. Component (e)(i) is compatible with (e)(ii), so if the zero-shear viscosity of component (e)(ii) is within the stated range, there appears to be no problem of component (e)(ii) penetrating into component (e)(i) and causing it to swell. However, given that the physically recycled and / or recovered silicone elastomer microparticles (e)(i) are thermosetting materials, they cannot dissolve in component (e)(ii) due to their crosslinking properties. Therefore, it instead swells to accommodate the organopolysiloxane polymer of component (e)(ii). Thus, the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are physically well bonded in the matrix and cannot act as defects in the matrix, thus creating voids, surface protrusions, or other heterogeneity, which is generally problematic when simply encapsulated and used as a filler.

[0090] In a first embodiment, physically recycled and / or recovered cured silicone rubber microparticles (e)(i) can be permeated and soaked in an organopolysiloxane polymer swelling agent (e)(ii) having a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25°C for a suitable period of time. In this embodiment, the organopolysiloxane polymer swelling agent (e)(ii) is preferably pure or undoped. A suitable period of time may be at least 1 hour, alternatively at least 12 hours, alternatively at least 24 hours, or alternatively at least 48 hours. This allows the organopolysiloxane polymer swelling agent (e)(ii) to permeate and swell the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) to form component (e). This corresponds to step (2) of the method described above. Subsequently, the resulting mixture of swollen (e)(i) and residual (e)(ii) is added to a curable high-temperature vulcanizable (HTV) silicone rubber composition or a portion thereof, typically part B when the curable high-temperature vulcanizable (HTV) silicone rubber composition is a hydrogenated silanization curable silicone rubber composition. This includes step (3) of the method described above.

[0091] As previously noted, steps (2), (3), and optional (4) may alternatively be performed simultaneously. In this embodiment, component (e) may be prepared by swelling physically recycled and / or recovered cured silicone rubber microparticles (e)(i) in a curable high-temperature vulcanizable (HTV) silicone rubber composition containing component (e)(ii), or more generally by swelling in a portion of the curable high-temperature vulcanizable (HTV) silicone rubber composition (when stored in multiple portions prior to use).

[0092] In such embodiments, swelling can occur throughout the period during which the microparticles (e)(i) are stored in the portion of the curable high-temperature vulcanizable (HTV) silicone rubber composition containing component (e)(ii).

[0093] When the organopolysiloxane polymer swelling agent (e)(ii) is initially stored in one part of a two-part composition, such as in part B of a hydrogenable silanization curable silicone rubber composition, it may be present in an amount of 2% to 10% by weight of part B before being mixed with part A in a 1:1 weight ratio. Typically, part B is used because it does not contain any catalyst. This is because the particles (e)(i) may contain Si-H groups, which, if mixed with a catalyst, can initiate some curing during storage.

[0094] In this embodiment, the organopolysiloxane polymer swelling agent (e)(ii) may comprise component (d)(i) crosslinking agent or at least 1.0% by weight of component (a) or a mixture of component (d)(i) and said at least 1.0% by weight of component (a), or may be an organopolysiloxane polymer plasticizer. After being added to the relevant portion of the composition containing component (e)(ii), the particles (e)(i) are swollen.

[0095] For example, a swelling agent may be introduced into part B of a hydrogenatinizable silanization curable silicone rubber composition (described in more detail later), and physically recycled and / or recovered cured silicone rubber microparticles (e)(i) may be swollen in part B of the composition for a predetermined period of time, after which part A may be mixed with part B of the composition and the composition may be cured.

[0096] Typically, throughout their entire service life, and even after curing, physically recycled and / or recovered cured silicone rubber microparticles (e)(i) will remain swollen in the presence of organopolysiloxane polymer swelling agents (e)(ii).

[0097] Swelling component (e)

[0098] Typically, after a predetermined time has elapsed since the particles of component (e)(i) have swelled with component (e)(ii), component (e) is present in an amount of 5% to 80% by weight of the curable high-temperature vulcanizable (HTV) silicone rubber composition, alternatively in an amount of 5% to 50% by weight, alternatively in an amount of 7.5% to 35% by weight, alternatively in an amount of 7.5% to 30% by weight, or alternatively in an amount of 9.0% to 25% by weight of the curable high-temperature vulcanizable (HTV) silicone rubber composition. The total weight percentage of the curable high-temperature vulcanizable (HTV) silicone rubber composition is 100% by weight.

[0099] Except for components (e)(i) and (e)(ii), the curable high-temperature vulcanizable (HTV) silicone rubber composition for preparing a high-temperature vulcanizable silicone rubber material having a Shore A hardness greater than 30 as determined using ASTM D2240-15 comprises the following components:

[0100] Component (a)

[0101] The components (a) of the curable high-temperature vulcanizable (HTV) silicone rubber composition, and the high Shore A hardness (>30) high-temperature vulcanizable silicone rubber material upon curing are:

[0102] (i) an organopolysiloxane polymer having a zero-shear viscosity at 25°C between 100 mPa·s and 200,000 mPa·s, including the terminal value, and having at least two unsaturated groups per molecule selected from alkenyl and / or alkynyl groups; or

[0103] (ii) an organopolysiloxane polymer adhesive having Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured according to ASTM D926-08, and having at least two unsaturated groups per molecule selected from alkenyl and / or alkynyl groups.

[0104] Each organopolysiloxane polymer of component (a) contains a plurality of silanoxy units of formula (I):

[0105]

[0106] The subscript "a" can be 0, 1, 2 or 3.

[0107] The silanoxy unit can be described by abbreviations, namely "M", "D", "T", and "Q", where R' is as described above, alternatively an alkyl group, usually a methyl group. The M unit corresponds to a silanoxy unit where a = 3, i.e., R'3SiO 1 / 2 The D unit corresponds to the silanoxy unit where a = 2, i.e., R'2SiO. 2 / 2 The T unit corresponds to the silanoxy unit where a = 1, i.e., R'1SiO. 3 / 2 The Q unit corresponds to the silanoxy unit where a=0, i.e., SiO2. 4 / 2 The organopolysiloxane polymer of component (a) is essentially linear, but may contain a certain proportion of branches due to the presence of T units within the molecule (as previously described), thus the average value of a in structure (I) is approximately 2.

[0108] The unsaturated group of component (a) may be located at the end or side chain of the organopolysiloxane polymer, or at both positions. The unsaturated group of component (a) may be an alkenyl group or an alkynyl group as described above. When present, each alkenyl group may 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 may be, but is not limited to, the following: vinyl, allyl, methyl allyl, propenyl, hexenyl, and cyclohexenyl groups. When present, each alkynyl group may 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 may be, but are not limited to, the following: ethynyl, propynyl, and butynyl groups. Preferred examples of unsaturated groups in component (a) include vinyl, propenyl, isopropenyl, butenyl, allyl, and 5-hexenyl.

[0109] In formula (I), in addition to the unsaturated groups described above, each R' is independently selected from aliphatic hydrocarbon groups, substituted aliphatic hydrocarbon groups, aromatic groups, or substituted aromatic groups. Each aliphatic hydrocarbon group may be exemplified by, but is not limited to, alkyl groups having 1 to 20 carbon / groups, alternatively 1 to 15 carbon / groups, alternatively 1 to 12 carbon / groups, alternatively 1 to 10 carbon / groups, alternatively 1 to 6 carbon / groups, or cycloalkyl groups, such as cyclohexyl. Specific examples of alkyl groups may 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.

[0110] Aliphatic nonhalogenated organic groups are exemplified by, but not limited to, the following: alkyl groups having substituted groups, such as suitable nitrogen-containing groups, such as amide groups, imino groups; oxygen-containing groups (such as polyoxyethylene groups, carbonyl groups, alkoxy groups, and hydroxyl groups). Other organic groups may include sulfur-containing groups, phosphorus-containing groups, and boron-containing groups. Examples of aromatic groups or substituted aromatic groups are phenyl groups and substituted phenyl groups having substituted groups as described above.

[0111] Component (a) may be selected, for example, from polydimethylsiloxane, alkylmethylpolysiloxane, alkylarylpolysiloxane or copolymers thereof (wherein alkyl means any suitable alkyl group, alternatively having two or more carbon alkyl groups), provided that each polymer has a zero shear viscosity of the organopolysiloxane polymer (a) that is between 100 mPa·s and 200,000 mPa·s, including the end value, at 25°C.

[0112] Therefore, for example, component (a) could be:

[0113] Dialkylene-terminated polydimethylsiloxanes, such as dimethylvinyl-terminated polydimethylsiloxanes; dialkylene-terminated dimethylmethylphenylsiloxanes, such as dimethylvinyl-terminated dimethylmethylphenylsiloxanes; trialkyl-terminated dimethylmethylvinyl polysiloxanes; dialkylvinyl-terminated dimethylmethylvinyl polysiloxane copolymers; dialkylvinyl-terminated methylphenyl polysiloxanes, dialkylene-terminated methylvinylmethylphenylsiloxanes; dialkylene-terminated methylvinyldiphenylsiloxanes; dialkylene-terminated methylvinylmethylphenyldimethylsiloxanes; trimethyl-terminated methylvinylmethylphenylsiloxanes; trimethyl-terminated methylvinylmethylphenylsiloxanes; or trimethyl-terminated methylvinylmethylphenyldimethylsiloxanes.

[0114] In each case, when the organopolysiloxane polymer of component (a) has a zero-shear viscosity between 100 mPa·s and 200,000 mPa·s (including the end value) at 25°C and at least two unsaturated groups per molecule (these unsaturated groups are selected from alkenyl and / or alkynyl groups), the viscosity of the organopolysiloxane polymer (a) should be between 100 mPa·s and 200,000 mPa·s (including the end value) at 25°C, alternatively between 1,000 mPa·s and 150,000 mPa·s at 25°C, alternatively between 1,000 mPa·s and 125,000 mPa·s at 25°C, alternatively between 1,000 mPa·s and 100,000 mPa·s at 25°C. These polymers are used to prepare “liquid silicone rubber” (LSR).

[0115] Unless otherwise stated, all viscosity measurements given are zero shear viscosity (η). o The zero-shear viscosity (ZHV) value is obtained by extrapolating values ​​acquired at low shear rates to zero or by simply averaging the viscosity-shear rate curve over a limiting range where the viscosity-shear rate curve is independent of the rate. This is a method-independent value provided a suitable and properly operated rheometer is used. For example, the zero-shear viscosity of a substance at 25°C can be obtained using a commercial rheometer, such as the Anton-Parr MCR-301 rheometer equipped with a cone-plate clamp of suitable diameter or the TA Instruments AR-2000 rheometer, at a range of low shear rates such as 0.01 s⁻¹. -1 0.1s -1 and 1.0s -1 This generates a sufficient torque signal without exceeding the transducer's torque limit. Alternatively, viscosity measurements can be taken using an ARES-G2 rotational rheometer, commercially available from TA Instruments, on a 25 mm cone plate using a 0.1 s... -1up to 10s -1 The stable rate scan is used to obtain the data. If a zero-shear plateau region cannot be observed at the shear rate achievable by the rheometer or viscometer, report a plateau at 0.1 s at 25°C. -1 Viscosity measured at the standard shear rate.

[0116] Alternatively, the organopolysiloxane polymer of component (a) has a Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured according to ASTM D926-08, and each molecule has at least two unsaturated groups selected from alkenyl and / or alkynyl groups. The organopolysiloxane polymer adhesive has a viscosity value of at least 1,000,000 mPa·s at 25°C and typically several million mPa·s at 25°C. Due to the difficulty in measuring these viscosity values, the adhesive is often described by its Williams plasticity value according to ASTM D926-08 rather than by viscosity. Therefore, when component (a) is an organopolysiloxane adhesive, the adhesive has Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured by ASTM D926-08, alternatively 100 mm / 100 to 450 mm / 100 as measured by ASTM D926-08, alternatively 120 mm / 100 to 400 mm / 100 as measured by ASTM D926-08, and alternatively 120 mm / 100 to 375 mm / 100 as measured by ASTM D926-08. These adhesives are used to prepare high-consistency silicone rubber materials (HCR).

[0117] Typically, for each organopolysiloxane polymer containing at least two silicon-bonded alkenyl groups per molecule of component (a), the alkenyl and / or alkynyl content (e.g., vinyl content) of the polymer is from 0.01 wt% to 3 wt%, alternatively, the organopolysiloxane or component (a) of each organopolysiloxane containing at least two unsaturated groups per molecule is from 0.01 wt% to 2.5 wt%, alternatively, component (a) is from 0.01 wt% to 2.0 wt%, or 0.01 wt% to 1.5 wt%, wherein these unsaturated groups are selected from the alkenyl and / or alkynyl groups of each molecule of component (a). The alkenyl / alkynyl content of component (a) is determined using quantitative infrared analysis according to ASTM E168.

[0118] Component (a) may be present in a curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare high-Shaughness A hardness (>30) high-temperature vulcanizable silicone rubber materials, in an amount of 40% to about 80% by weight of the curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare high-Shaughness A hardness (>30) hydrogenated silane-cured elastomer silicone rubber materials, alternatively in an amount of 45% to 80% by weight of the composition used to prepare high-Shaughness A hardness (>30) hydrogenated silane-cured elastomer silicone rubber materials, alternatively in an amount of 50% to 80% by weight of the curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare high-Shaughness A hardness (>30) hydrogenated silane-cured elastomer silicone rubber materials. Typically, component (a) is present as the difference between 100% by weight of the composition and the cumulative weight percentage of other components / ingredients.

[0119] Component (b)

[0120] Component (b) of the curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare high Shore A hardness (>30) high-temperature vulcanizable silicone rubber materials is one or more fillers, in an amount of 20.0% to 50% by weight of the composition. The fillers may be reinforcing fillers, non-reinforcing fillers, or mixtures thereof.

[0121] The filler can be a reinforcing filler comprising pyrolytic silica, precipitated silica, or mixtures thereof. A finely granulated form of silica is preferred. The reinforcing filler is provided to enhance the physical properties of the elastomer provided when the composition is cured. Reinforcing filler (b) is used, for example, a silica filler having a relatively high surface area, typically at least 50 m². 2 / g (according to the BET method of ISO 9277:2010). For example, it is common to use 50m 2 / g-450m 2 / g, 50m alternative location 2 / g-400m 2 / g, 50m alternative location 2 / g to 300m 2 / g, 100m of alternative location 2 / g-300m 2 Filler (e.g., pyrolytic silica) with a surface area of ​​ / g (according to the BET method of ISO 9277: 2010).

[0122] Typically, the reinforcing filler (b) is a naturally hydrophilic (e.g., untreated) silica filler, and is therefore treated with a treatment agent to make it / them hydrophobic. These surface-modified reinforcing fillers (b) do not clump and can be uniformly incorporated into the organopolysiloxane polymer (a) described below, because the surface treatment makes the filler readily wettable by the organopolysiloxane polymer (a).

[0123] Component (b) may optionally or additionally contain one or more non-reinforced fillers.

[0124] Non-reinforcing fillers suitable for component (b) may include pulverized quartz, diatomaceous earth, barium sulfate, iron oxide, titanium dioxide and carbon black, talc, and wollastonite. Other fillers that may be used alone or in addition to the fillers mentioned above include alumina, calcium sulfate (anhydrite), gypsum, calcium sulfate, precipitated calcium carbonate, ground calcium carbonate, magnesium carbonate, clay (such as kaolin), magnesium hydroxide (e.g., brucite), graphite, copper carbonate (e.g., malachite), nickel carbonate (e.g., niobite), barium carbonate (e.g., barite), and / or strontium carbonate (e.g., strontium sappan).

[0125] Other fillers may include silicates selected from the group consisting of: olivine; garnet; aluminosilicates; cyclosilicates; chain silicates; and platy silicates. Olivine includes silicate minerals such as, but not limited to, forsterite and Mg₂SiO₄. Garnet includes ground silicate minerals such as, but not limited to, pyrope; Mg₃Al₂Si₃O₄. 12 Grossular garnet and Ca2Al2Si3O 12 Aluminosilicates include milled silicate minerals such as, but not limited to, sillimanite; Al₂SiO₅; mullite; 3Al₂O₃·2SiO₂; kyanite; and Al₂SiO₅. Cyclosilicates can be used as non-reinforcing fillers; these include silicate minerals such as, but not limited to, cordierite and Al₃(Mg,Fe)₂[Si₄AlO₂]. 18 Chain silicates include ground silicate minerals, such as, but not limited to, wollastonite and Ca[SiO3]. Flake silicates may alternatively or otherwise be used as non-reinforcing fillers, wherein suitable classes contain silicate minerals, such as, but not limited to, mica; K2Al 14 [Si6Al2O 20 (OH)4; pyrophyllite; Al4[Si8O 20 (OH)4; Talc; Mg6[Si8O 20 (OH)4; serpentine, for example asbestos; kaolinite; Al4[Si4O] 10 (OH)8; and vermiculite.

[0126] Typically, one or more fillers (b) can be surface-treated with any low molecular weight organosilicon compound disclosed in the art suitable for preventing wrinkling of organosiloxane compositions during processing. For example, organosilanes, polydiorganosiloxanes, or organosilazanes (e.g., hexaalkyldisilazane), short-chain siloxane diols, or fatty acids or fatty acid esters such as stearates can be used to impart hydrophobicity to the filler and thus facilitate processing and obtain homogeneous mixtures with other components. Specific examples include, but are not limited to, silanol-terminated trifluoropropylmethylsiloxanes, silanol-terminated vinylmethylsiloxanes, tetramethyldisilazane, tetramethyldivinyldisilazane, hexamethyldisilazane (HMDZ), silanol-terminated MePh siloxanes, liquid hydroxyl-terminated polydiorganosiloxanes, hexaorganodisilazanes, and hexaorganodisilazanes containing an average of 2 to 20 diorganosiloxane repeating units per molecule. A small amount of water and a silica treatment agent as a processing aid may be added.

[0127] One or more fillers (b) may be pretreated before being introduced into the curable high-temperature vulcanizable (HTV) silicone rubber composition, or may be treated in situ (i.e., by blending these components together at room temperature or higher until the filler is fully treated, in the presence of at least a portion of the other components of the curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare the high Shore A hardness (>30) high-temperature vulcanizable silicone rubber material described herein). Typically, one or more fillers (b) are treated in situ with a treatment agent in the presence of an organopolysiloxane polymer (a) to prepare a silicone rubber matrix material, which may then be blended with other components.

[0128] One or more fillers (b) are present in a curable high-temperature vulcanizable (HTV) silicone rubber composition for preparing a high-Shaughness A hardness (>30) high-temperature vulcanizable silicone rubber material, in an amount of 20.0% to 50% by weight, or alternatively 20% to 45% by weight, of the composition for preparing a high-Shaughness A hardness (>30) high-temperature vulcanizable silicone rubber material. Alternatively, in a composition for preparing a high-Shaughness A hardness (>30) hydrogenated silanized curable elastomeric silicone rubber material, 20% to 40% by weight is present. Alternatively, in a composition for preparing a high-Shaughness A hardness (>30) high-temperature vulcanizable silicone rubber material, 20% to 35% by weight is present. In an alternative, the filler will be selected from one or more of the following: pyrolytic silica, precipitated silica, calcium carbonate, talc, mica, and / or quartz; alternatively, it will contain reinforcing fillers pyrolytic silica, precipitated silica, or mixtures thereof, or constitute thereof.

[0129] Component (c)

[0130] Component (c) of the compositions described herein is a free radical initiator, typically in the form of an organic peroxide. The organic peroxide free radical initiator can be any of the well-known commercial peroxides used for curing high-temperature vulcanizable (HTV) compositions. Typically, the free radical initiator is combined with the organopolysiloxane rubber of component (a) and fillers (b), particularly reinforcing fillers of component (b), to prepare a high-consistency rubber composition. The amount of free radical initiator (e.g., organic peroxide) used is determined by the nature of the curing process, the organic peroxide used, and the composition used. Typically, the amount of peroxide catalyst used in the compositions as described herein is from 0.2% to 3% by weight, or alternatively from 0.2% to 2% by weight, based on the weight of the composition in each case. Suitable organic peroxides that can be used as free radical initiators include, but are not limited to, substituted or unsubstituted dialkyl peroxides, alkyl aryl peroxides, and diaryl peroxides, such as benzoyl peroxide and 2,4-dichlorobenzoyl peroxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butylisopropyl peroxide, bis(tert-butylperoxyisopropyl)benzene, bis(tert-butylperoxy)-2,5-dimethylhexyne, 2,4-dimethyl-2,5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide, and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane. Mixtures of the above may also be used.

[0131] Component (d)

[0132] Component (d) of the curable high-temperature vulcanizable (HTV) composition described herein is a hydrosilylation catalyst package containing...

[0133] (i) a polydiorganosiloxane polymer having at least two or at least three Si-H groups per molecule, used as a crosslinking agent; and

[0134] (ii) Hydrogenation silanization catalyst.

[0135] Component (d)(i)

[0136] Component (d)(i) of a curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare a high-Shaughness A hardness (>30) high-temperature vulcanizable silicone rubber material serves as a crosslinking agent and is provided in the form of a silicone compound having an average of at least two, alternatively at least three, Si-H groups per molecule. Component (d)(i) typically contains three or more silicon-bonded hydrogen atoms, so that the hydrogen atoms can react with the unsaturated groups (alkenyl and / or alkynyl groups) of component (a) and / or the remainder of the composition to form a network structure therewith, thereby curing the composition to prepare a high-Shaughness A hardness (>30) hydrogenated silanized elastomeric silicone rubber material. Alternatively, some or all of component (d)(i) may have two silicon-bonded hydrogen atoms per molecule. However, when, for example, polymer (a) has more than two unsaturated groups per molecule, such a molecule is used only as the sole crosslinking agent, in which case a network can be formed during curing. Otherwise, when component (d)(i) contains a molecule having an average of two silicon-bonded hydrogen atoms per molecule, the molecule can be used as a chain extender.

[0137] The molecular configuration of organosilicon compounds (d)(i) having at least two, alternatively at least three Si-H groups per molecule is not specifically limited, and they may be silanes, or straight-chain, branched (a straight chain with some branches by the presence of T units), or cyclic polymers, or based on organosilicon resins.

[0138] All viscosities were measured at 25°C and were zero-shear measurements using the previously described method.

[0139] The silicon-bonded organic group used in component (d)(i) may 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, particularly methyl, ethyl, or propyl groups or phenyl groups. Preferably, the silicon-bonded organic group used in component (d)(i) is an alkyl group, alternatively a methyl, ethyl, or propyl group.

[0140] Examples of organosilicon compounds (d)(i) having an average of at least two, and optionally at least three, Si-H groups per molecule include, but are not limited to:

[0141] (a') Trimethylsiloxy-terminated methylhydropolysiloxane

[0142] (b') Trimethylsiloxy-terminated polydimethylsiloxane-methylhydrosiloxane

[0143] (c') Dimethylsiloxane-methylhydrosiloxane copolymer with dimethylhydrosiloxane end-capped

[0144] (d') dimethylsiloxane-methylhydrosiloxane cyclic copolymer

[0145] (e') is derived from (CH3)2HSiO 1 / 2 Unit, (CH3)3SiO 1 / 2 unit and SiO 4 / 2 copolymers and / or silicone resins composed of units,

[0146] (f') is derived from (CH3)2HSiO 1 / 2 unit and SiO 4 / 2 copolymers and / or silicone resins composed of units,

[0147] (g') A methylhydrosiloxane cyclic homopolymer having 3 to 10 silicon atoms per molecule. Alternatively, the crosslinking agent of component (d)(i) may be a filler, such as silica treated with one of the above substances, and mixtures thereof.

[0148] In one embodiment, component (d)(i) is selected from methylhydrosiloxanes capped at both ends with trimethylsiloxy groups; copolymers of methylhydrosiloxanes and dimethylsiloxanes capped at both ends with trimethylsiloxy groups; dimethylsiloxanes capped at both ends with dimethylhydrosiloxy groups; and copolymers of methylhydrosiloxanes and dimethylsiloxanes capped at both ends with dimethylhydrosiloxy groups.

[0149] The crosslinking agent (d)(i) is typically present in curable high-temperature vulcanizable (HTV) silicone rubber compositions used to prepare high-Shore A hardness (>30) high-temperature vulcanizable silicone rubber materials, such that the molar ratio of silicon-bonded hydrogen atoms in component (d)(i) to the total unsaturated groups selected from alkenyl and / or alkynyl groups in the composition is 0.5:1 to 20:1. When this ratio is less than 0.5:1, a well-cured composition is not obtained. When this ratio exceeds 20:1, the hardness of the cured curable high-temperature vulcanizable (HTV) silicone rubber composition tends to increase upon heating.

[0150] The molar ratio of the silicon-bonded hydrogen atoms of component (d)(i) to the total unsaturated groups selected from alkenyl and / or alkynyl groups in the organopolysiloxane (a) of the hydrogenosilane-curable silicone rubber composition is preferably at least 0.8:1, alternatively 1:1, and can be as high as 8:1 or 10:1. Most preferably, the molar ratio of Si-H groups to aliphatic unsaturated groups is in the range of 1.1:1 to 5:1.

[0151] The silicon-bonded hydrogen (Si-H) content of component (d)(i) was determined using quantitative infrared analysis according to ASTM E168. In this case, the ratio of silicon-bonded hydrogen to alkenyl (vinyl) and / or alkynyl groups is important when relying on a hydrogen silane curing process. Generally, this is determined by calculating the total weight % of alkenyl groups, such as vinyl [V], in the curable high-temperature vulcanizable (HTV) silicone rubber composition and the total weight % of silicon-bonded hydrogen [H] in the composition, and assuming a molecular weight of 1 for hydrogen and a molecular weight of 27 for vinyl, the molar ratio of silicon-bonded hydrogen to vinyl is 27[H] / [V].

[0152] Typically, depending on the number of unsaturated groups in component (a) and the remainder of the curable high-temperature vulcanizable (HTV) silicone rubber composition and the number of Si-H groups in component (d)(i), component (d)(i) will be present in the following amounts: 0.1% to 2% by weight of the composition for preparing a high Shore A hardness (>30) hydrogenated silane-cured elastomeric silicone rubber material; alternatively, 0.1% to 1.5% by weight of the composition for preparing a high Shore A hardness (>30) hydrogenated silane-cured elastomeric silicone rubber material; alternatively, 0.25% to 1.0% by weight of the composition for preparing a high Shore A hardness (>30) hydrogenated silane-cured elastomeric silicone rubber material; and further alternatively, 0.3% to 1% by weight of the composition for preparing a high Shore A hardness (>30) hydrogenated silane-cured elastomeric silicone rubber material.

[0153] (d)(ii) Hydrosilylation catalyst

[0154] Component (d)(ii) of the curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare a high Shore A hardness (>30) hydrogenated silanization curable elastomeric silicone rubber material is a hydrogenated silanization catalyst comprising or consisting of a platinum group metal or a compound thereof. These catalysts are typically selected from catalysts of platinum group metals (platinum, ruthenium, osmium, rhodium, iridium, and palladium), or compounds of one or more of these metals. Alternatively, platinum and rhodium compounds are preferred due to the high activity levels of these catalysts in the hydrogenated silanization reaction, with platinum compounds being the most preferred. In the hydrogenated silanization (or addition) reaction, the hydrogenated silanization catalyst, such as component (d)(ii) herein, catalyzes the reaction between unsaturated groups (typically alkenyl groups, e.g., vinyl groups) and Si-H groups.

[0155] The hydrosilylation catalyst of components (d) and (ii) can be a platinum group metal, a platinum group metal deposited on a support (such as activated carbon, metal oxides such as silica, silica gel, or charcoal powder), or a compound or complex of a platinum group metal. Preferably, the platinum group metal is platinum.

[0156] Examples of preferred hydrosilylation catalysts for components (d) and (ii) include platinum-based catalysts such as platinum black, platinum oxide (Adams catalyst), platinum on various solid supports, chloroplatinic acid (e.g., hexachloroplatinic acid (Pt oxidation state IV) (Speyer catalyst)), solutions of chloroplatinic acid in alcohols (e.g., isooctyl alcohol or pentanol) (Ramoro catalyst), and complexes of chloroplatinic acid with olefinically unsaturated compounds (such as alkenes and organosiloxanes containing olefinically unsaturated silicon-bonded hydrocarbon groups), such as tetravinyltetramethylcyclotetrasiloxane-platinum complexes (Ashby catalyst). Soluble platinum compounds that can be used include, for example, platinum-olefin complexes of the formula (PtCl2.olefin)2 and H(PtCl3.olefin), preferably in this context olefins having 2 to 8 carbon atoms, such as isomers of ethylene, propylene, butene, and octene, or cycloalkanes having 5 to 7 carbon atoms, such as cyclopentene, cyclohexene, and cycloheptene. Other soluble platinum catalysts include, for example, platinum-cyclopropane complexes of formula (PtCl2C3H6)2, reaction products of hexachloroplatinic acid with alcohols, ethers, and aldehydes, or mixtures thereof, or reaction products of hexachloroplatinic acid and / or its conversion products with vinylsiloxanes (such as methylvinylcyclotetrasiloxane) in the presence of an ethanol solution containing sodium bicarbonate. Platinum catalysts with phosphorus, sulfur, and amine ligands, such as (Ph3P)2PtCl2, can also be used; as well as platinum complexes with vinylsiloxanes, such as symmetrical divinyltetramethyldisiloxane (Castel catalyst).

[0157] Therefore, specific examples of suitable platinum-based catalysts for component (d)(ii) include:

[0158] (i) A complex of chloroplatinic acid as described in US 3,419,593 with an organosiloxane containing an olefinic unsaturated hydrocarbon group.

[0159] (ii) Chloroplatinic acid in hexahydrate or anhydrous form;

[0160] (iii) A platinum-containing catalyst, which is obtained by a method comprising the steps of reacting chloroplatinic acid with an aliphatic unsaturated organosilicon compound (such as divinyltetramethyldisiloxane);

[0161] (iv) olefin-platinum-silyl complexes as described in U.S. Patent No. 6,605,734, such as (COD)Pt(SiMeCl2), where “CO” is 1,5-cyclooctadiene; and / or

[0162] (v) Karstedt catalyst, i.e., a platinum-divinyltetramethyldisiloxane complex typically containing about 1% by weight of platinum in a vinylsiloxane polymer. Solvents such as toluene and similar organic solvents have historically been used as alternatives, but the use of vinylsiloxane polymers is currently the preferred choice. These are described in US3,715,334 and US3,814,730. In a preferred embodiment, component (d) and (ii) may be selected from platinum coordination compounds. In one embodiment, hexachloroplatinic acid and its conversion products with vinyl-containing siloxanes, the Karstedt catalyst, and the Speier catalyst are preferred. In one embodiment, the catalyst may be encapsulated during storage, especially in the case of a single-component composition, to prevent premature curing.

[0163] The catalytic amount of the hydrogenation silanization catalyst is based on the weight of the curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare high Shore A hardness (>30) hydrogenation silanization cured elastomeric silicone rubber materials, and is typically between 0.01 ppm and 10,000 parts by weight of platinum group metals per million parts (ppm); alternatively between 0.1 ppm and 7,500 ppm; alternatively between 100 ppm and 75,000 ppm; and alternatively between 500 ppm and 6,000 ppm. This range may refer only to the metal content within the catalyst or to the entire catalyst (including its ligands) as detailed, but typically these ranges refer only to the metal content within the catalyst. The catalyst may be added as a single substance or as a mixture of two or more different substances. Typically, depending on the form / concentration of the catalyst provided (e.g., in the polymer or solvent), the amount of component (d)(ii) present will be in the range of 0.001% by weight to 3.0% by weight of the curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare a high Shore A hardness (>30) hydrogenated silanized curable elastomeric silicone rubber material; alternatively, the curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare a high Shore A hardness (>30) hydrogenated silanized curable elastomeric silicone rubber material has 0.001% to 1.5% by weight of the silicone rubber composition; alternatively, 0.01%–1.5% by weight of the curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare high Shore A hardness (>30) hydrogenated silane-cured elastomeric silicone rubber materials; alternatively, 0.01% to 0.1.0% by weight of the curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare high Shore A hardness (>30) hydrogenated silane-cured elastomeric silicone rubber materials.

[0164] When present, components (a) and (d) (i) always consist of a mixture of macromolecules with different degrees of polymerization and therefore different molecular weights. Different types of average polymer molecular weights exist, which can be measured in different experiments. The two most important average polymer molecular weights are number-average molecular weight (Mn) and weight-average molecular weight (Mw). Mn and Mw of silicone polymers and / or resins can be determined by gel permeation chromatography (GPC) using polystyrene calibration standards. This technique is standard and produces Mw, Mn, and the polydispersity index (PI). Degree of polymerization (DP) = Mn / Mu, where Mn is the number-average molecular weight measured from GPC, and Mu is the molecular weight of the monomer unit. PI = Mw / Mn. DP is related to the viscosity of the polymer via Mw; the higher the DP, the higher the viscosity. Silicone resins typically have a weight-average molecular weight (Mn) of 2,000 to 50,000 Daltons, alternatively 3,000 to 40,000 Daltons, alternatively 3,000 to 30,000 Daltons, alternatively 4,000 to 30,000 Daltons, and alternatively 5,000 to 25,000 Daltons. w The molecular weight was determined by gel permeation chromatography using a triple detector system (e.g., light scattering detector, refractive index detector, and / or viscosity detector) and polystyrene standards.

[0165] Additional optional ingredients

[0166] Depending on their intended end use, additional optional components may be present in the curable high-temperature vulcanizable (HTV) silicone rubber compositions described above. Examples of such optional components include curing inhibitors, pot life extenders, flame retardants, adhesion promoters, lubricants, metal passivators, pigments and / or colorants, bactericides, wetting agents, heat stabilizers, compression set additives, plasticizers, silicone resins, and mixtures thereof.

[0167] Component (d)(i) may also be present in HTV-curable silicone rubber compositions cured by free radical initiators. This is optional because the stoichiometry of Si-H with olefinically unsaturated groups is less critical and can be extended beyond the scope referenced in hydrogenosilane-curable compositions, while still providing effective curing. In these cases, a smaller amount of component (d)(i) than when used in hydrogenosilane-curable compositions can generally be used to contribute to effective curing.

[0168] When a curable high-temperature vulcanizable (HTV) silicone rubber composition as described above is cured via an addition / hydrosilaneation reaction, a curing inhibitor can be used to suppress the curing of the composition. These curing inhibitors are used to prevent premature curing during storage and / or to achieve a longer working time or pot life of the hydrosilaneized cured composition by delaying or inhibiting the activity of the catalyst. Curing inhibitors for hydrosilaneation catalysts (d)(ii) (e.g., platinum-based catalysts) are well known in the art and may include hydrazines, triazoles, phosphines, thiols, organonitrogen compounds, alkynyl alcohols, silylated alkynyl alcohols, maleate esters (such as dibutyl maleate); fumarate esters, olefinic or aromatic unsaturated amides, olefinic unsaturated isocyanates, olefin siloxanes (such as tetramethyltetravinylcyclotetrasiloxane), unsaturated hydrocarbon monoesters and diesters, conjugated alkynylenes, hydroperoxides, nitriles, and diazacyclopropanes. Alkenyl-substituted siloxanes, as described in US 3,989,667, may be used, with cyclic methyl vinyl siloxanes being preferred.

[0169] Known curing inhibitors for hydrogenation silylation catalysts, such as platinum catalysts (d)(ii), include alkynyl compounds disclosed in US 3,445,420. Alynyl alcohols, such as 2-methyl-3-butyn-2-ol, constitute a preferred class of curing inhibitors, which inhibit the activity of platinum-containing catalysts at 25°C. Compositions containing these curing inhibitors typically require heating at 70°C or higher to achieve curing at an achievable rate.

[0170] Examples of alkynols and their derivatives include 1-ethynyl-1-cyclohexanol (ETCH), 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-methylbutynol, 3-butyn-2-ol, propargyl alcohol, 2-phenyl-2-propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclopentanol, 1-phenyl-2-propynol, 3-methyl-1-penten-4-yn-3-ol, and mixtures thereof. In an alternative, the curing inhibitor is selected from one or more of 1-ethynyl-1-cyclohexanol (ETCH), tetramethyltetravinylcyclotetrasiloxane, 3-methylbutynol, and / or dibutyl maleate.

[0171] When present, a curing inhibitor concentration as low as 1 mole of curing inhibitor per mole of catalyst (d)(ii) will, in some cases, impart satisfactory storage stability and curing rate. In other cases, a curing inhibitor concentration of up to 500 moles of curing inhibitor per mole of catalyst (d)(ii) is required. The optimal concentration of a given curing inhibitor in a given curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare the high Shore A hardness (>30) high-temperature vulcanizable silicone rubber material described herein can be readily determined by routine experiments. The mixtures described above may also be used. Depending on the concentration and form in which the selected curing inhibitor is provided / commercially available, the curing inhibitor is typically present in the composition in amounts of 0.0001 wt% to 10 wt%, alternatively 0.001 wt% to 5 wt% of curing inhibitor, or alternatively 0.0125 wt% to 5 wt% of the composition.

[0172] Pot life extenders, such as triazoles, may be used, but are not considered essential within the scope of this invention. Therefore, curable high-temperature vulcanizable (HTV) silicone rubber compositions used to prepare high Shore A hardness (>30) high-temperature vulcanizable silicone rubber materials may be free of pot life extenders.

[0173] Examples of flame retardants include calcium carbonate (e.g., precipitated calcium carbonate), aluminum trihydrate (ATH), magnesium dihydroxyl hydroxide (MDH), and HMH (a mixture of magnesia and calcium carbonate), chlorinated paraffin, hexabromocyclododecane, triphenyl phosphate, dimethyl methylphosphonate, tris(2,3-dibromopropyl) phosphate (tribromoester), and mixtures or derivatives thereof. When present in the composition, the flame retardant may be present in an amount from 5% to 50% by weight of the composition, if desired.

[0174] Adhesion promoter

[0175] When available, any suitable adhesion promoter may be used if desired. Adhesion promoters may be, for example, alkoxysilane coupling agents. Examples of adhesion promoters that can be incorporated into the curable compositions according to the invention include alkoxysilanes such as aminoalkylalkoxysilanes, such as 3-aminopropyltriethoxysilane, epoxyalkylalkoxysilanes, such as 3-glycidoxypropyltrimethoxysilane, and mercaptoalkylalkoxysilane, as well as reaction products of ethylenediamine with silyl acrylates. Isocyanurates containing silicon groups, such as 1,3,5-tris(trialkoxysilylalkyl)isocyanurate, may also be used. Other suitable adhesion promoters are reaction products of epoxyalkylalkoxysilanes (such as 3-glycidoxypropyltrimethoxysilane) with amino-substituted alkoxysilanes (such as 3-aminopropyltrimethoxysilane) and optionally with alkylalkoxysilanes (such as methyl-trimethoxysilane). When present, the adhesion promoter may be present in amounts from 0.1% to 5.0% by weight of the composition, alternatively from 0.1% to about 3.5% by weight of the composition, alternatively from 0.1% to 2.5% by weight of the composition, alternatively from 0.1% to 2.25% by weight of the composition, and alternatively from 0.2% to 2.0% by weight of the composition. Other suitable adhesion promoters are epoxyalkylalkoxysilanes (such as 3-glycidyl etheroxypropyltrimethoxysilane) reacting with amino-substituted alkoxysilanes (such as 3-aminopropyltrimethoxysilane) and optionally reaction products with alkylalkoxysilanes (such as methyl-trimethoxysilane).

[0176] In an alternative, the adhesion promoter can be a combination of an alkoxysilane coupling agent and an organometallic adhesion catalyst, such as zirconium tetraacetylacetonate (IV) (sometimes referred to as zirconium AcAc4) or aluminum triacetylacetonate (III) (sometimes referred to as aluminum AcAc3). Typically, such catalysts are introduced in an amount of 0.05% to 0.3% by weight of the composition.

[0177] Examples of lubricants include tetrafluoroethylene, resin powder, graphite, fluorinated graphite, talc, boron nitride, fluorinated oil, silicone oil, molybdenum disulfide, and mixtures or derivatives thereof. When present in curable high-temperature vulcanizable (HTV) silicone rubber compositions used to prepare high Shore A hardness (>30) hydrogenated silanized elastomeric silicone rubber materials, flame retardants are typically present in an amount of 0.1% to 5% by weight of the composition.

[0178] Examples of pigments include titanium dioxide, chromium trioxide, bismuth vanadium oxide, iron oxide, and mixtures thereof.

[0179] Examples of colorants that can be used in curable high-temperature vulcanizable (HTV) silicone rubber compositions for preparing high Shore A hardness (>30) high-temperature vulcanizable silicone rubber materials include pigments, vat dyes, reactive dyes, acid dyes, chromium dyes, disperse dyes, cationic dyes, and mixtures thereof. The curable high-temperature vulcanizable (HTV) silicone rubber compositions described herein may further contain one or more pigments and / or colorants, which may be added if desired. Pigments and / or colorants can be colored, white, black, metallic, and luminescent, such as fluorescent and phosphorescent. Pigments are used to color the composition as needed. Any suitable pigment can be used, provided it is compatible with the composition used to prepare the high Shore A hardness (>30) high-temperature vulcanizable silicone rubber materials described herein.

[0180] Suitable white pigments and / or colorants include titanium dioxide, zinc oxide, lead oxide, zinc sulfide, zinc barium white, zirconium oxide, and antimony oxide.

[0181] Suitable non-white inorganic pigments and / or colorants include, but are not limited to, iron oxide pigments such as goethite, lepidocrocite, hematite, maghemite, and maghemite black, yellow, brown, and red iron oxides; blue iron pigments; chromium oxide pigments; cadmium pigments such as cadmium yellow, cadmium red, and cadmium cinnabar; bismuth pigments such as bismuth vanadate and bismuth vanadate; mixed metal oxide pigments such as cobalt titanate green; chromate and molybdate pigments such as chrome yellow, molybdenum red, and molybdenum orange; ultramarine pigments; cobalt oxide pigments; nickel antimony titanate; lead chromium; carbon black; lampblack; and metallic effect pigments such as aluminum, copper, copper oxide, bronze, stainless steel, nickel, zinc, and brass.

[0182] Suitable organic non-white pigments and / or colorants include phthalocyanine pigments, such as phthalocyanine blue and phthalocyanine green; monoaryl yellow, diaryl yellow, benzimidazolone yellow, heterocyclic yellow, DAN orange, quinacridone pigments, such as quinacridone fuchsin and quinacridone violet; organic reds, including metallized azo red and non-metallized azo red, as well as other azo pigments, monoazo pigments, diazo pigments, azo pigment lakes, β-naphthol pigments, naphthol AS pigments, benzimidazolone pigments, diazo condensation pigments, isoindolineone and isoindoline pigments, polycyclic pigments, perylene and fenone pigments, thioindole pigments, anthraquinone pigments, yellow anthrone pigments, anthraquinone pigments, dioxazine pigments, triarylcarbene pigments, quinacridone pigments, and diketopyrrolopyrrole pigments.

[0183] Typically, pigments and / or colorants, when in particulate form, have an average particle size in the range of 10 nm to 50 µm, preferably in the range of 40 nm to 2 µm. Pigments and dyes can be used in the form of pigment masterbatches composed of which they are dispersed in component (a) at a ratio of 25:75 to 70:30.

[0184] Curable high-temperature vulcanizable (HTV) silicone rubber compositions used to prepare high Shore A hardness (>30) high-temperature vulcanizable silicone rubber materials can be heat-stable. Examples of heat stabilizers may include metal compounds such as iron oxide red, iron oxide yellow, iron hydroxide, cerium oxide, cerium hydroxide, lanthanum oxide, copper phthalocyanine, pyrolytic titanium dioxide, iron naphthenate, cerium naphthenate, dimethyl polysiloxane cerium, and acetylacetone salts of metals selected from copper, zinc, aluminum, iron, cerium, zirconium, titanium, etc. Other examples of heat stabilizers may include suitable antioxidants or metal scavengers such as 1,2-bis(3,5-di-tert-butyl-4-hydroxycinnamoyl)hydrazine, 2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide, and N'1,N'12-bis(2-hydroxybenzoyl)dodecanedihydrazine. When present in a curable high-temperature vulcanizable (HTV) silicone rubber composition, the amount of heat stabilizer may be in the range of 0.01% by weight to 1.0% by weight of the curable high-temperature vulcanizable (HTV) silicone rubber composition.

[0185] Organosilicon resin

[0186] The curable high-temperature vulcanizable (HTV) silicone rubber composition used to prepare high Shore A hardness (>30) high-temperature vulcanizable silicone rubber materials is a silicone resin containing unsaturated groups selected from alkenyl groups, alkynyl groups, or a mixture of alkenyl and alkynyl groups, specifically selected from T silicone resin (silsesquioxane), DT silicone resin, MQ silicone resin, MDT silicone resin, MTQ silicone resin, QDT silicone resin, or mixtures thereof.

[0187] Resins using the MDTQ designation contain Q-type (SiO2) resins. 4 / 2 ) siloxane unit, T-type (R 2 1SiO 3 / 2 ) siloxane unit; D-type (R 2 1SiO 3 / 2 ) siloxane unit and R 2 3SiO 1 / 2 (M) Siloxane units. These resins can be divided into two main categories: silsesquioxanes and silicates. Silsesquioxane or T resins are mainly composed of T units and can be synthesized by hydrolysis and condensation of alkoxysilanes, chlorosilanes, or mixtures thereof. Silicate or MQ resins are mainly composed of M and Q units and can be synthesized by hydrolysis and condensation of alkoxysilanes and chlorosilanes. Alternatively, MQ resins can be synthesized by polymerization of aqueous alkali metal silicates in the presence of acid, followed by reaction with triorganoalkoxysilanes, triorganochlorosilanes, hexaorganodisiloxanes, or mixtures thereof.

[0188] Preferably, when present, the silicone resin is one or more MQ resins. Typically, MQ resins (when present) contain SiO₂. 4 / 2 (Q) Siloxane unit and R 2 3SiO 1 / 2 (M) siloxane units, wherein each R 2 They can be the same or different and represent monovalent groups selected from hydrocarbon groups, having 1 to 20 carbon atoms and alternatively 1 to 12 carbon atoms. A suitable R... 2 Examples of groups include alkyl groups, such as methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl; alicyclic groups, such as cyclohexyl; alkenyl groups having 2 to 12 carbons, such as vinyl, propynyl, butenyl, pentenyl, and hexenyl; alkynyl groups selected from ethynyl, propynyl, butynyl, pentynyl, or hexynyl; aryl groups, such as phenyl, tolyl, xylyl, benzyl, α-methylstyryl, and 2-phenylethyl; and alternatively, R 2 The group is a vinyl, methyl, ethyl, or phenyl group, such as the preferred R group. 2 3SiO 1 / 2 Examples of (M) siloxane units include Me3SiO 1 / 2 PhMe2SiO 1 / 2 ViMe2SiO 1 / 2 and Ph2MeSiO 1 / 2 In this context, Me represents methyl, Vi represents vinyl, and Ph represents phenyl. Alternatively, the T silicone resin may be referred to as sesquioxane. Silicone resins can be a single silicone resin or a mixture containing two or more different silicone resins (each as described above). Typically, they are ViMe2SiO 1 / 2

[0189] With Me3SiO 1 / 2 and / or PhMe2SiO 1 / 2 MQ resin with a combination of functional groups.

[0190] In addition, silicone resins may contain residual OZ. 5 MQ resin, of which Z 5 It can represent hydrogen or alkyl groups. OZ 5 The presence of groups on the Q component after the synthesis of the organosilicon MQ resin indicates incomplete condensation during the reaction process of MQ resin production, provided that the OZ content meets the aforementioned requirement of hydroxyl groups per mole of Si. Residual OZ 5 This is inherent to the process and reactions used in the manufacture of MQ resin. The MQ resin can also undergo subsequent silylation reactions to further minimize residual OZ. 5 .

[0191] When present, silicone resins are typically delivered in hydrocarbon or silicone solvents. In the absence of solvents, silicone resins are typically solids, but it is preferred herein that silicone resins are delivered in silicone solvents such as nonfunctionalized polydimethylsiloxanes or polydimethylsiloxanes containing two or more alkenyl groups per molecule (such as component (a) in this document, for example).

[0192] For example, any suitable MQ resin can be used if desired. The molar ratio of M siloxane units to Q siloxane units has a value of 0.5:1 to 1.2:1, alternatively 0.6:1 to 1.1:1, alternatively 0.8:1 to 1.1:1, or alternatively 0.9:1 to 1.1:1. In one embodiment, the MQ resin (e) comprises a resin portion wherein the M units are bonded to SiO2. 4 / 2 The siloxane unit (i.e., the Q unit), and each unit in the Q unit is bonded to at least one other SiO2. 4 / 2 Siloxane units. The molar ratio of M units to Q units is 0.3:1 to 1.2:1, alternatively 0.4:1 to 1.1:1, alternatively 0.5:1 to 1:1, or alternatively 0.6:1 to 0.9:1. Such MQ resins may have a number-average molecular weight (Mn) of 2000 g / mol to 50,000 g / mol, or alternatively 3,000 g / mol to 30,000 g / mol. In one embodiment, the silicone resin can be described according to its molar fraction as an MQ silicone resin having the following formula:

[0193]

[0194] Where R 4 C1 to C1 without aliphatic unsaturation 10 The hydrocarbon group, u is 0.3 to 0.6, or alternatively 0.37 to 0.52, v is 0.4 to 0.7, or alternatively 0.48 to 0.63, and the value of u+v is 1.0.

[0195] Methods for preparing organosilicon resins are well known in the art. For example, they can be prepared by treating resin copolymers produced by silica hydrosol end-capping methods with end-capping agents containing alkyl and / or alkenyl groups. This method preferably involves reacting a silica hydrosol under acidic conditions with hydrolyzable triorganosilanes such as trimethylchlorosilane, siloxanes such as hexamethyldisiloxane, and combinations thereof, followed by recovery of the M(R3SiO) group. 1 / 2 ) unit and Q(SiO) 4 / 2 The copolymer comprises units ranging from 0.07 moles of hydroxyl groups per mole of silicon (Si) to 0.2 moles of hydroxyl groups per mole of Si. The copolymer can be further reacted with a capping agent comprising saturated organic groups to achieve less than 0.06 moles of hydroxyl groups per mole of Si. Suitable capping agents include silazanes, siloxanes, silanes, and combinations thereof.

[0196] Silicone resins are typically delivered in hydrocarbon or silicone solvents. In the absence of solvent, silicone resins are usually solid, but it is preferred herein that silicone resins are delivered in silicone solvents such as nonfunctionalized polydimethylsiloxanes or polydimethylsiloxanes containing two or more alkenyl groups per molecule (such as component (a) in this document, for example).

[0197] When present, the silicone resin described above may be present in the curable high-temperature vulcanizable (HTV) silicone rubber composition in an amount of 1% to 60% by weight, or alternatively 1% to 40% by weight, and preferably in the form of MQ resin.

[0198] Methods for preparing organosilicon resins are well known in the art. For example, they can be prepared by treating resin copolymers produced by silica hydrosol end-capping methods with end-capping agents containing alkyl and / or alkenyl groups. This method preferably involves reacting a silica hydrosol under acidic conditions with hydrolyzable triorganosilanes such as trimethylchlorosilane, siloxanes such as hexamethyldisiloxane, and combinations thereof, followed by recovery of the M(R3SiO) group. 1 / 2 ) unit and Q(SiO) 4 / 2 The copolymer comprises units ranging from 0.07 moles of hydroxyl groups per mole of silicon (Si) to 0.2 moles of hydroxyl groups per mole of Si. The copolymer can be further reacted with a capping agent comprising saturated organic groups to achieve less than 0.06 moles of hydroxyl groups per mole of Si. Suitable capping agents include silazanes, siloxanes, silanes, and combinations thereof.

[0199] Therefore, the curable high-temperature vulcanizable (HTV) silicone rubber composition for preparing a high-temperature vulcanizable silicone rubber material having a Shore A hardness greater than 30 as determined by ASTM D2240-15 comprises:

[0200] a) An organopolysiloxane polymer having a zero-shear viscosity at 25°C between 100 mPa·s and 200,000 mPa·s (including the end value), alternatively between 1,000 mPa·s and 150,000 mPa·s at 25°C, optionally between 1,000 mPa·s and 125,000 mPa·s, optionally between 1,000 mPa·s and 70,000 mPa·s at 25°C, and each molecule having at least two unsaturated groups selected from alkenyl and / or alkynyl groups, or

[0201] An organopolysiloxane polymer adhesive having Williams plasticity of 75 mm / 100 to 500 mm / 100, alternatively 100 mm / 100 to 450 mm / 100, alternatively 120 mm / 100 to 400 mm / 100, and alternatively 120 mm / 100 to 375 mm / 100 as measured according to ASTM D926-08, and having at least two unsaturated groups per molecule selected from alkenyl and / or alkynyl groups;

[0202] The amount is from 40% to about 80% by weight of the composition, alternatively from 45% to 80% by weight of the composition, alternatively from 50% to 80% by weight of the composition; unless otherwise specified, all viscosity measurements given are zero-shear viscosities (η) determined as described above. o The values ​​were measured, and in the embodiments, all were performed at 25°C.

[0203] (b) One or more fillers in an amount of 20.0% to 50% by weight of the composition, said filler may be reinforced filler or unreinforced filler (b), and is generally treated to make it hydrophobic, and is present in an amount of 20.0% to 50% by weight of the composition, alternatively 20% to 45% by weight of the composition, alternatively 20% to 40% by weight of the composition, alternatively 20% to 35% by weight of the composition; (c) or (d), wherein

[0204] (c) A free radical initiator catalyst used in the compositions described herein, in each case based on the weight of the composition, in an amount of 0.2% to 3% by weight, alternatively 0.2% to 2% by weight, such as substituted or unsubstituted dialkyl peroxides, alkyl aryl peroxides, diaryl peroxides, for example benzoyl peroxide and 2,4-dichlorobenzoyl peroxide, di-tert-butyl peroxide, dicumyl peroxide, tert-butyl isopropyl peroxide, bis(tert-butylperoxy)benzene, bis(tert-butylperoxy)-2,5-dimethylhexyne, 2,4-dimethyl-2,5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide, and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane. Mixtures of the above may also be used.

[0205] (d) is a hydrogenation silylation catalyst package, which contains...

[0206] (d)(i) An organosilicon compound having an average of at least two or alternatively at least three Si-H groups per molecule, preferably wherein the molar ratio of silicon-bonded hydrogen atoms in component (d)(i) to the total unsaturated groups selected from alkenyl and / or alkynyl groups in the composition is from 0.5:1 to 20:1, and alternatively the molar ratio of silicon-bonded hydrogen atoms in component (d)(i) to the total unsaturated groups selected from alkenyl and / or alkynyl groups in the organopolysiloxane (a) is preferably at least 1:1, and can be up to 8:1 or 10:1. Most preferably, the molar ratio of Si-H groups to aliphatic unsaturated groups is in the range of 1.1:1 to 5:1; each molecule of the organosilicon compound has an average of at least two, alternatively at least three Si-H groups, present in amounts of 0.1 wt% to 2 wt% of the composition, 0.1 wt% to 1.5 wt% of the curable high-temperature vulcanizable (HTV) silicone rubber composition, alternatively 0.25 wt% to 1.0 wt% of the curable high-temperature vulcanizable (HTV) silicone rubber composition, and further alternatively 0.3 wt% to 1 wt% of the curable high-temperature vulcanizable (HTV) silicone rubber composition. Component (d)(i) is used as a crosslinking agent;

[0207] (d)(ii) a hydrogenation silanization curing catalyst, wherein the catalytic amount of the hydrogenation silanization catalyst is based on the weight of the curable high-temperature vulcanizable (HTV) silicone rubber composition and is between 0.01 ppm and 10,000 parts by weight of platinum group metals per million (ppm); alternatively between 0.1 ppm and 7,500 ppm; alternatively between 100 ppm and 75,000 ppm of metals, alternatively between 500 ppm and 6,000 ppm of metals, based on the weight of the composition, and wherein, depending on the form / concentration provided by the catalyst (e.g., in a polymer or solvent), the amount of component (d)(ii) present will be in the range of 0.001 wt% to 3.0 wt% of the composition, alternatively between 0.001 wt% to 1.5 wt% of the composition, alternatively between 0.01 wt% to 1.5 wt% of the composition, alternatively between 0.01 wt% to 0.1.0 wt% of the curable high-temperature vulcanizable (HTV) silicone rubber composition; and

[0208] (e) Physically recycled and / or recovered cured silicone rubber microparticles (e)(i) having an average unswelled particle size of 1 mm or less, which have been infiltrated and swollen by an organopolysiloxane polymer swelling agent (e)(ii) having a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25°C; said component (e) is present in the composition in an amount of 7.5% to 30% by weight, alternatively in an amount of 7.5% to 25% by weight, or alternatively in an amount of 9.0% to 20% by weight, after a predetermined time has elapsed since component (e)(i) was swollen by component (e)(ii);

[0209] The composition may also contain one or more of the optional additives mentioned above, as needed and when required. The total weight percentage of the composition is 100% by weight.

[0210] The curable high-temperature vulcanizable (HTV) silicone rubber composition can be a hydrogenated silanized curing composition containing components (a), (b), (d), and (e) or a free radical activated composition containing components (a), (b), (c), and (e).

[0211] Typically, when a curable high-temperature vulcanizable (HTV) silicone rubber composition is used to prepare a high-temperature vulcanizable silicone rubber material having a Shore A hardness greater than 30 as determined by ASTM D2240-15, the composition comprises components (a), (b), (d), and (e) and is stored in two parts (Part A and Part B) to keep components (d)(i) (crosslinking agent) and (d)(ii) (hydrosilane curing catalyst) separate to avoid premature curing. Typically, Part A will comprise component (a) a polymer, (b) one or more fillers; alternatively, it will include reinforcing fillers or one or more fillers thereof, and (d)(ii) (hydrosilane curing catalyst), and Part B comprises components (a), (d)(i) a crosslinking agent, one or more fillers (b); alternatively, it will include reinforcing fillers or one or more fillers thereof (b), and optionally a curing inhibitor (if present).

[0212] After the physically recycled and / or recovered high-temperature vulcanized (HTV) silicone rubber microparticles (e)(i) have swelled (e)(ii), component (e) may be introduced into the part B composition. Alternatively, the microparticles (e) may swell in the part B composition, in which case the swelling agent (e)(ii) may be introduced into the part B composition before or simultaneously with the microparticles (e)(i), or when some components (a) have a sufficiently low viscosity (i.e., less than 15,000 mPa·s), component (a) may be used at least partially as component (e)(ii), in which case component (e)(i) may be added directly to the part B composition and allowed to swell for a certain period of time. When components (e)(i) and (e)(ii) are mixed together in the premix, once the time period allowed for the swelling of component (e)(i) expires, the premix of component (e) can be added directly to part B, or it can be kept alone or together with additional component (a) in the composition of part C, and then part C is mixed into the final composition while parts A and B are mixed together.

[0213] Other optional additives in curable high-temperature vulcanizable (HTV) silicone rubber compositions used to prepare high-temperature vulcanizable silicone rubber materials having a Shore A hardness greater than 30 as determined by ASTM D2240-15 (i.e., other than curing inhibitors (when present)) may be in part A or part B, provided that they do not adversely affect the properties of any other components present (e.g., catalyst deactivation).

[0214] Shortly before use, portions A and B of a curable high-temperature vulcanizable (HTV) silicone rubber composition in the form of a hydrogenated silanizable curable silicone rubber composition as described herein are mixed together to initiate the curing of the entire composition into a cured elastomeric silicone rubber material having a Shore A hardness greater than 30 as determined using ASTM D2240-15. The composition of portions A and B (and optionally, the composition containing portion C (e)) can be designed to be mixed in any suitable weight ratio, for example, portion A: portion B can be mixed in a weight ratio of 10:1 to 1:10, alternatively 5:1 to 1:5, alternatively 2:1 to 1:2, but most preferably a weight ratio of 1:1.

[0215] The components of Part A and Part B can be mixed together separately in any suitable manner, wherein the components are introduced individually or in combination that can be prepared in advance, for example, to facilitate mixing of the final composition.

[0216] For example, components (a) and (b) are typically mixed together to form a polymer matrix or masterbatch before being added with other ingredients, wherein silica is optionally treated in situ. Similarly, component (e) may also be premixed with component (a) if desired. These can then be mixed with other components of part B prepared directly, or used to prepare pre-concentrated concentrates commonly referred to in the industry as masterbatches.

[0217] Any mixing techniques and apparatus described in the prior art can be used to prepare the composition of part A and part B. The specific apparatus to be used will depend on the viscosity of the components and the final composition. Suitable mixers include, but are not limited to, paddle mixers, such as planetary mixers and kneader-type mixers. It may be desirable to cool the components during mixing to prevent premature curing of the composition.

[0218] Curable high-temperature vulcanizable (HTV) silicone rubber compositions, as described above, can be placed in a mold or applied to a substrate, etc., and then cured using any suitable known technique. Curing of the curable high-temperature vulcanizable (HTV) silicone rubber composition can be carried out in a mold to form a molded part by injection molding using, for example, a liquid injection molding system (LIMS), compression molding, extrusion, transfer molding, pressure vulcanization, or calendering. The curable high-temperature vulcanizable (HTV) silicone rubber composition is cured at any suitable temperature (e.g., at 80°C to 200°C, alternatively about 100°C to 180°C, alternatively about 120°C to 180°C) to produce a high-temperature vulcanizable silicone rubber material with a Shore A hardness greater than 30 as determined using ASTM D2240-15.

[0219] The hydrogenated silanized cured elastomeric silicone rubber materials described herein, having a Shore A hardness greater than 30 as determined using ASTM D2240-15, can be used for a variety of end applications, such as, for illustrative purposes, the manufacture of gaskets and seals, adhesives, coatings, molded rubber products, hoses and tubing such as medical tubing, encapsulants and potting compounds, etc. Example

[0220] In the following examples, unless otherwise stated, the compositions are defined in weight % (wt. %).

[0221] The content of vinyl groups and Si-H groups was measured by infrared spectroscopy according to ASTM E168 standards for carbon double bond elongation and organosilicon hydrogen bond elongation, respectively.

[0222] Unless otherwise stated, all viscosity measurements given are zero shear viscosity (η). oThe zero-shear viscosity (ZHV) value is obtained by extrapolating values ​​acquired at low shear rates to zero or by simply averaging the viscosity-shear rate curve over a limiting range where the viscosity-shear rate curve is independent of the rate. This is a method-independent value provided a suitable and properly operated rheometer is used. For example, the zero-shear viscosity of a substance at 25°C can be obtained using a commercial rheometer, such as the Anton-Parr MCR-301 rheometer equipped with a cone-plate clamp of suitable diameter or the TA Instruments AR-2000 rheometer, at a range of low shear rates such as 0.01 s⁻¹. -1 0.1s -1 and 1.0s -1 This generates a sufficient torque signal without exceeding the transducer's torque limit. Alternatively, viscosity measurements can be taken using an ARES-G2 rotational rheometer, commercially available from TA Instruments, on a 25 mm cone plate using a 0.1 s... -1 up to 10s -1 The stable rate scan is used to obtain the data. If a zero-shear plateau region cannot be observed at the shear rate achievable by the rheometer or viscometer, report a plateau at 0.1 s at 25°C. -1 Viscosities were measured at standard shear rates. Unless otherwise specified, all viscosity measurements were obtained at 25°C. All Shore hardness measurements were taken using the Shore A hardness scale as defined in ASTM D2240-15.

[0223] Swelling reference example

[0224] To demonstrate that the low-viscosity organopolysiloxane polymer of component (e)(ii) will swell and be silanized and cured into an organosilicon elastomer, the following experiments were conducted when the elastomer was immersed / soaked in the low-viscosity organopolysiloxane polymer.

[0225] Prepare a sheet of hydrogenated silanized curable liquid silicone rubber material according to the instructions supplied with the product for mixing the provided two-part composition. Cut three 1-inch × 1-inch × 0.08-inch (2.54 cm × 2.54 cm × 0.2 mm) rectangular samples from the sheet. Immerse the three rectangular samples in three dimethyl vinyl-terminated polydimethylsiloxanes with different viscosities: the first polysiloxane polymer has a zero-shear viscosity of about 30 mPa·s, the second polysiloxane polymer has a zero-shear viscosity of about 430 mPa·s, and the third polysiloxane polymer has a zero-shear viscosity of about 44,000 mPa·s, with the zero-shear value measured at 25°C as described above in each case. Each sample is kept immersed in the corresponding polysiloxane polymer for 24 hours, after which their changes are analyzed.

[0226] It was found that samples immersed in an organopolysiloxane polymer with a zero shear viscosity of 44,000 mPa·s did not increase in mass or change in size. Samples immersed in an organopolysiloxane polymer with a viscosity of 430 mPa·s showed an 8% increase in both mass and size. Samples immersed in an organopolysiloxane polymer with a viscosity of 30 mPa·s showed a 30% increase in both mass and size.

[0227] Therefore, it can be seen that swelling does occur when the sample is immersed in a low-viscosity organopolysiloxane polymer, but no significant swelling occurs when immersed in an organopolysiloxane polymer with a zero-shear viscosity of 44,000 mPa·s.

[0228] Laboratory preparation of microparticles

[0229] In one example, samples of cured silicone rubber blocks were shredded using a paper shredder and cut with scissors until they had a predetermined particle size of less than 2 cm. These were then fed into a Mikro feeder, commercially available from Hosokawa Micron Corporation. ™ In the UMP-B grinder, shredded / cut rubber samples are mixed with dry ice (previously pulverized into powder using a mortar and pestle) at approximately a 1:1 weight ratio to lower the rubber's temperature and help it harden for grinding. The rubber / dry ice mixture is then fed into the grinder using a blade rotor rotating at >10,000 rpm. The rubber is then allowed to exit the grinding chamber through a stainless steel sieve as it is cut finer than the mesh size of the sieve. The sieve has round holes with a diameter of 2mm-3mm for the first pass. The rubber ground in the first pass can then be subjected to a second pass with dry ice as described above, this time fed through a Mikro sieve with a 1mm grooved sieve. ™ Perform a second pass using the UMP-B grinder.

[0230] Particle size analysis and evaluation .

[0231] The particle size distribution of the milled silicone elastomer microparticles was measured using laser diffraction. A Beckman Coulter with a Tornado (dry) module was used. ™ LS 13 320 particle size analyzer. Approximately 25 mL of ground, blocky solid sample was added to a vial, placed in the LS 13320 Tornado module, and then activated. Upon activation, the Tornado module automatically evacuates the sample through a laser and measures the sample's diffraction signal. The result was then analyzed using a Beckman Coulter. ™ The software deconvolve the diffraction signal to obtain the particle size distribution determined using the Fraunhofer diffraction model.

[0232] Prepare curable high-temperature vulcanizable (HTV) silicone rubber compositions in the form of hydrogenated silanization curable silicone rubber compositions using the compositions shown in Table 1.

[0233] Table 1: Hydrogen-silanized curable silicone rubber compositions (LSR 1) (wt%)

[0234]

[0235] The reactive swelling agent used is a vinyl dimethyl-terminated polydimethylsiloxane fluid with a viscosity of 450 mPa·s.

[0236] The crosslinking agent used in the above composition is a trimethyl-terminated methylhydrodimethylsiloxane polymer with a zero shear viscosity of about 15 mPa·s.

[0237] According to ASTM D 2240, in the absence of physical recycling and / or recovered particles, the Shore A hardness value of the above composition once cured is 35.

[0238] Table 2: Part B compositions containing microparticles and reactive swelling agents (parts relative to Part B)

[0239]

[0240] In the table above, the particulate load is expressed as parts by weight / 100 parts by weight of the corresponding B(1) or B(2) part composition as defined in Table 1.

[0241] In the above:

[0242] Physically recycled and / or recovered silicone rubber 1 microparticles are prepared from a hydrogenated silanized and cured liquid silicone rubber (LSR) coating composition containing HMDZ-treated pyrolytic silica with a Shore A hardness of approximately 40. Prior to conversion into microparticles, it has a Shore A hardness value of approximately 40 as measured according to ASTM D 2240-15.

[0243] Physically recycled and / or recycled silicone rubber 2 microparticles are prepared from peroxide-cured high-consistency rubber (HCR) having a Shore A hardness of approximately 60 as measured according to ASTM D 2240-15, which can be used for applications such as gaskets.

[0244] Therefore, in both cases, when cured in the absence of the aforementioned physically recycled and / or recycled silicone rubber, the difference in Shore A hardness between the composition and the aforementioned physically recycled and / or recycled silicone rubber is therefore less than 30.

[0245] In Ref. 1, C.1, and C.2, the B-part compositions shown in Table 1 were prepared in the absence of a reactive swelling agent, and in Ex. 1 and Ex. 2, the B(2)-part compositions shown in Table 1 were prepared in the presence of a reactive swelling agent. The relevant physically recycled and / or recovered microparticles as indicated in Table 2 were introduced into the corresponding B(1) and B(2)-part compositions of C.1, C.2, Ex. 1, and Ex. 2, and the microparticles used in Ex. 1 and Ex. 2 were swollen by interacting with the provided reactive swelling agent. In Ex. 1 and 2, swelling was carried out for approximately 24 hours.

[0246] After the swelling step is completed, the resulting mixture containing 100 parts by weight of the B-part composition incorporating the swollen microparticles is mixed with 100 parts by weight of the A-part composition of LSR 1 (excluding microparticles, the A-part:B-part weight ratio is 1:1), resulting in the presence of microparticles equivalent to approximately 10% by weight (unswollen weight) in the total A-part + B-part composition. Hydrogen-silanizable curable silicone rubber compositions are obtained by compression molding rectangular plates of different compositions with dimensions of 5 inches × 5 inches × 0.08 inches (12.7 cm × 12.7 cm × 0.2 cm) at 150°C for 10 minutes.

[0247] After curing, the physical properties of the cured samples were analyzed according to the ASTM methods described below, and the results are shown in Tables 3a (Shore A Hardness) and 3b (Tension Test). For the tensile test, tensile test bars with a gauge length of 40 mm were cut from a rectangular plate using a metal die; otherwise, the tensile strength, elongation at break, and modulus at 100% elongation were determined according to ASTM D412. Five parallel determinations were performed for each sample.

[0248] Table 3a: Shore A hardness measurements for Ref. 1, C.1 and C.2 and Ex.1 to Ex.2 (ASTM D2240-15) .

[0249]

[0250] Table 3b: Tensile properties according to ASTM D412 Ref. 1, C.1, C.2 and Ex.1 to Ex.2 and their relationship with Ref. 1 Comparison .

[0251]

[0252] As can be understood from the results in Table 3b, an increase in the elongation at break can be observed in Ex.1 and Ex.2 compared to the results of Comparative Examples C.1 and C.2. This indicates that, when measured according to ASTM D2240-15, when the difference in Shore A hardness between the liquid silicone rubber of Table 1 and the silicone rubber from which the particles are physically recycled and / or recycled is less than 30 on the Shore A scale, the inclusion of a reactive swelling agent (a swelling agent that participates in the curing of the composition and may interact with the physically recycled and / or recycled particle portion) in the composition of part B(2) positively affects the tensile properties, regardless of how the physically recycled and / or recycled particles were initially cured.

[0253] It can also be seen that, once cured, similar tensile strength and elongation at break results increase due to the addition of physically recycled and / or recovered microparticles swollen with reactive swelling agents to the composition. The reactive swelling agent appears to have a greater positive effect when the difference in Shore A hardness between the liquid silicone rubber in Table 1 and the silicone rubber from which the microparticles are physically recycled and / or recovered is close to zero (i.e., they are approximately the same value on the Shore A scale). This will be evident when comparing Ex.1 with C.1 and Ex.2 with C.2.

[0254] In further evaluation, the composition of Ex.1 was compared with the same formulation (Ex.1*) using physically recycled and / or recovered microparticles with an average particle size of 400 µm, and the results are provided in Table 4 below:

[0255] Table 4: Comparison of physical properties of Ex.1* with Ref. 1, C.1 and Ex.1

[0256]

[0257] It can be seen that Ex.1* does indeed provide improved tensile strength and elongation results compared to Ex.1 and C.1, and has a similar modulus at 100% elongation, and the Shore A hardness results are also similar. Therefore, reducing the particle size seems to have some advantages for this type of composition.

Claims

1. A high-temperature vulcanizable silicone rubber material having a Shore A hardness greater than 30 as determined by ASTM D2240-15, which is a cured product of a curable high-temperature vulcanizable (HTV) silicone rubber composition, the curable high-temperature vulcanizable (HTV) silicone rubber composition comprising... (a) An organopolysiloxane polymer having a zero-shear viscosity at 25°C between 100 mPa·s and 200,000 mPa·s, including the terminal value, and having at least two unsaturated groups per molecule, said unsaturated groups being selected from alkenyl and / or alkynyl groups, or An organopolysiloxane polymer adhesive having Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured according to ASTM D926-08, and having at least two unsaturated groups per molecule, said unsaturated groups being selected from alkenyl and / or alkynyl groups; (b) One or more fillers in an amount of 20.0% to 50% by weight of the composition; (c) or (d), where (c) is a free radical initiator; or (d) is a hydrogenation silylation catalyst package, which contains... (ii) An organosilicon compound in an amount of 0.1% to 2% by weight of the composition, wherein each molecule of the organosilicon compound has an average of at least two or alternatively at least three Si-H groups; as well as (ii) Hydrosilylation catalyst; as well as (e) Physically recycled and / or recovered cured silicone rubber microparticles (e)(i) having an average unswelled particle size of 1 mm or less, wherein the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) have been infiltrated and swollen by an organopolysiloxane polymer swelling agent (e)(ii) having a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25°C; The physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are obtained from a cured silicone rubber elastomer having a Shore A hardness greater than 30 as determined by ASTM D2240-15, and the difference in Shore A hardness between the high-temperature vulcanized silicone rubber material having a Shore A hardness greater than 30 and the cured silicone rubber elastomer from which the component (e)(i) is physically recycled and / or recovered is less than or equal to 30 as determined by ASTM D2240-15.

2. The high-temperature vulcanized silicone rubber material according to claim 1, wherein the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are obtained from a cured silicone rubber elastomer, which is prepared from a composition that can be hydrogenated and silanized, a free radical curing composition, or a photocurable composition.

3. The high-temperature vulcanized silicone rubber material according to claim 2, wherein the source of the cured silicone rubber elastomer prepared from the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) is airbag coatings, gaskets and sealing adhesives, coatings, molded rubber products, hoses, pipes, foams, encapsulants and potting compounds.

4. A curable high-temperature vulcanizable (HTV) silicone rubber composition, wherein the curable high-temperature vulcanizable (HTV) silicone rubber composition comprises a) An organopolysiloxane polymer having a zero-shear viscosity at 25°C between 100 mPa·s and 200,000 mPa·s (including the end value), and having at least two unsaturated groups per molecule, said unsaturated groups being selected from alkenyl and / or alkynyl groups, or An organopolysiloxane polymer adhesive having Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured according to ASTM D926-08, and having at least two unsaturated groups per molecule, said unsaturated groups being selected from alkenyl and / or alkynyl groups; b) One or more fillers in an amount of 20.0% to 50% by weight of the composition; (c) or (d), where (c) is a free radical initiator; or (d) is a hydrogenation silylation catalyst package, which contains... (i) an organosilicon compound in an amount of 0.1% to 2% by weight of the composition, wherein each molecule of the organosilicon compound has an average of at least two or alternatively at least three Si-H groups; as well as (ii) Hydrosilylation catalyst; as well as e) Physically recycled and / or recovered cured silicone rubber microparticles (e)(i) having an average unswelled particle size of 1 mm or less, wherein the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) have been infiltrated and swollen by an organopolysiloxane polymer swelling agent (e)(ii) having a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25°C; in (i) The physically recycled and / or recovered cured silicone rubber microparticles (e) (i) are obtained from a cured silicone rubber elastomer having a Shore A hardness value of at least 30 as determined using ASTM D2240-15; (ii) The composition, upon curing, has a Shore A hardness greater than or equal to 30, as determined using ASTM D2240-15; and The difference between the Shore A values ​​of (iii), (i), and (ii) is less than or equal to 30 as determined using ASTM D2240-15.

5. The curable high-temperature vulcanizable (HTV) silicone rubber composition according to claim 4, wherein the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are obtained from a silicone rubber elastomer, the silicone rubber elastomer being prepared from a cured silicone rubber elastomer, the cured silicone rubber elastomer being prepared from a hydrogenated silanization curable composition, a free radical curable composition, or a photocurable composition.

6. The curable high-temperature vulcanizable (HTV) silicone rubber composition according to claim 5, wherein the physically recycled and / or recovered silicone rubber elastomer is obtained from airbag coatings, gaskets and sealing adhesives, coatings, molding rubber articles, hoses, pipe foams, encapsulants and potting compounds.

7. The curable high-temperature vulcanizable (HTV) silicone rubber composition according to claim 4, 5 or 6, wherein component (e) (ii) has a zero shear viscosity of 100 mPa·s to 5,000 mPa·s at 25°C.

8. The curable high-temperature vulcanizable (HTV) silicone rubber composition according to claim 4, 5, 6 or 7, wherein the composition further comprises one or more additives selected from: curing inhibitors, pot life extenders, flame retardants, adhesion promoters, lubricants, metal passivators, pigments and / or colorants, bactericides, wetting agents, heat stabilizers, compression set additives, plasticizers, silicone resins and mixtures thereof.

9. A method for preparing high-temperature vulcanized silicone rubber material, the method comprising the following steps: (1) Physically recycled and / or recovered cured silicone rubber microparticles with an average unswelled particle size of 1 mm or less are obtained from cured silicone rubber elastomers having a Shore A hardness of at least 30 as determined by ASTM D2240-15. (2) The cured silicone rubber microparticles (e)(i) from the physical recycling and / or recovery of step (1) are mixed with an organopolysiloxane polymer swelling agent (e)(ii) having a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25°C for a defined period of time, so that the organopolysiloxane polymer swelling agent (e)(ii) can penetrate and swell the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) to form component (e); (3) Forming the mixture of step (3), said mixture comprising at least a portion of components (a) and (e) and optionally one or more of components (b), (c) and / or (d); wherein a) An organopolysiloxane polymer having a zero-shear viscosity at 25°C between 100 mPa·s and 200,000 mPa·s (including the end value), and having at least two unsaturated groups per molecule, said unsaturated groups being selected from alkenyl and / or alkynyl groups, or An organopolysiloxane polymer adhesive having Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured according to ASTM D926-08, and having at least two unsaturated groups per molecule, said unsaturated groups being selected from alkenyl and / or alkynyl groups; b) One or more fillers in an amount of 20.0% to 50% by weight of the composition; (c) or (d), where (c) is a free radical initiator; or (d) is a hydrogenation silylation catalyst package, which contains... (i) an organosilicon compound in an amount of 0.1% to 2% by weight of the composition, wherein each molecule of the organosilicon compound has an average of at least two or alternatively at least three Si-H groups; as well as (ii) Hydrosilylation catalyst; (4) Mix the mixture from step (3) with the remaining portions of components (a), (b), (c) and / or (d) to produce a curable, high-temperature vulcanizable (HTV) silicone rubber composition. (5) Curing the curable high-temperature vulcanizable (HTV) silicone rubber composition at a temperature of 100°C to 200°C to form a high-temperature vulcanizable silicone rubber material having a Shore A hardness greater than 30 as determined using ASTM D2240-15. The difference in Shore A hardness between the high-temperature vulcanized silicone rubber material having a Shore A hardness greater than 30 and the cured silicone rubber elastomer of component (e)(i) by physical recycling and / or recovery is less than or equal to 30 as determined using ASTM D2240-15.

10. The method of claim 9, wherein steps (2), (3) and optional step (4) are performed together as a single step.

11. The method according to claim 9 or 10, wherein component (e)(i) is physically recycled and / or recovered cured silicone rubber microparticles (e)(i) obtained from a silicone rubber elastomer, said silicone rubber elastomer being prepared from a composition that can be hydrogenated and silanized, a free radical curing composition or a photocurable composition.

12. The method according to claim 11, wherein the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are prepared by milling, grinding or pulverizing silicone elastomers into microparticles.

13. The method according to claim 9, 10, 11 or 12, wherein component (e)(ii) has a zero shear viscosity of 100 mPa·s to 5,000 mPa·s at 25°C.

14. The method according to claim 9, 10, 11, 12 or 13, wherein the composition is a hydrogenatable silanization curable composition comprising components (a), (b), (d) and (e) or a radical-activated composition comprising components (a), (b), (c) and (e).

15. A high-temperature vulcanized silicone rubber material, said high-temperature vulcanized silicone rubber material being prepared by the method according to any one of claims 9, 10, 11, 12, 13 or 14.

16. Use of physically recycled and / or recovered cured silicone rubber microparticles (e)(i) having an average unswelled particle size of 1 mm or less in high-temperature vulcanized silicone rubber materials having a Shore A hardness greater than 30 as determined using ASTM D2240-15, wherein the physically recycled and / or recovered cured silicone rubber microparticles (e)(i) have been infiltrated and swollen by an organopolysiloxane polymer swelling agent (e)(ii) having a zero shear viscosity of less than or equal to (≤) 15,000 mPa·s at 25°C; and The physically recycled and / or recovered cured silicone rubber microparticles (e)(i) are obtained from a cured silicone rubber elastomer having a Shore A hardness value of at least 30 as determined using ASTM D2240-15; The high-temperature vulcanizable silicone rubber material is a cured product of a curable high-temperature vulcanizable (HTV) silicone rubber composition, wherein the curable high-temperature vulcanizable (HTV) silicone rubber composition comprises, in other respects, a) An organopolysiloxane polymer having a zero-shear viscosity at 25°C between 100 mPa·s and 200,000 mPa·s (including the end value), and having at least two unsaturated groups per molecule, said unsaturated groups being selected from alkenyl and / or alkynyl groups, or An organopolysiloxane polymer adhesive having Williams plasticity of 75 mm / 100 to 500 mm / 100 as measured according to ASTM D926-08, and having at least two unsaturated groups per molecule, said unsaturated groups being selected from alkenyl and / or alkynyl groups; b) One or more fillers in an amount of 20.0% to 50% by weight of the composition; (c) or (d), where (c) is a free radical initiator; or (d)(i) is a hydrogenation silylation catalyst package, which contains... (i) an organosilicon compound in an amount of 0.1% to 2% by weight of the composition, wherein each molecule of the organosilicon compound has an average of at least two or alternatively at least three Si-H groups; and (ii) Hydrosilylation catalyst; The difference in Shore A hardness between the high-temperature vulcanized silicone rubber material having a Shore A hardness greater than 30 and the high-temperature vulcanized (HTV) silicone rubber elastomer of component (e)(i) by its physical recycling and / or recovery is less than or equal to 30 as determined using ASTM D2240-15.

17. The use of a high-temperature vulcanizable silicone rubber material having a Shore A hardness greater than 30 as determined by ASTM D2240-15 as described in claims 1, 2, 3, or 15 in or as used in gaskets, seals, adhesives, coatings, molded rubber products, hoses, encapsulants, and potting compounds, and / or the use of a curable high-temperature vulcanizable (HTV) silicone rubber composition as described in claims 4 to 8 in or for use in the manufacture of gaskets, seals, adhesives, coatings, molded rubber products, hoses, encapsulants, and potting compounds.

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