Tough silicone rubber foam insulation

Abstract

An insulating / thermal protection barrier for providing insulation and protection to battery cells of a battery assembly, the barrier including a cured silicone rubber foam layer including a toughening material, such as a plurality of toughening particles disposed within the silicone rubber foam layer, in an amount sufficient to impart additional toughness to the silicone rubber foam layer such that a greater compressive force is required to compress the foam layer to a desired compressive value as compared to the same silicone rubber foam layer without the toughening particles.

Description

[Technical field]

[0001] The present disclosure relates generally to the field of silicone rubber foams, and more particularly to the field of thermally insulating silicone rubber foams (e.g., in sheet form) that are toughened to exhibit improved protective properties. The present disclosure also relates to methods for producing such silicone rubber foams and their use for industrial applications, particularly for battery thermal management applications (e.g., in the electric vehicle automotive industry). [Background technology]

[0002] Automotive electrification is currently one of the biggest trends in the automotive industry. In electric vehicles, the source of electrical energy is provided by battery cells in the form of a battery assembly (e.g., module, pack, etc.). In such an assembly, the battery cells are typically placed adjacent to each other and separated by a gap. Electric vehicle batteries are used to power the propulsion systems of battery electric vehicles (BEVs) and hybrid electric vehicles (HEVs). These batteries are typically lithium-ion batteries and are designed with high ampere-hour capacity. The trend in electric vehicle battery development is to increase the energy density (kWh / kg) in the battery, allowing longer distances to be covered and shorter charging times for the battery.

[0003] Due to the high energy density of electric vehicle batteries and the high energy flow during charging or discharging of the batteries, there is a risk of hot spots and thermal runaway events occurring, where heat generated by a decomposed or otherwise damaged battery cell propagates very quickly to adjacent cells. Such hot spots and thermal runaway events can also cause the affected battery cell to expand, which reduces the distance between the affected battery cell and adjacent battery cells. This chain reaction can result in an explosion or fire spreading throughout the electric vehicle.

[0004] In that context, the use of thermal management solutions has rapidly emerged as a way to mitigate the temperature rise of the battery assemblies. One partial solution is disclosed in US Patent Application Publication No. 2007 / 0259258(A1) (Buck), which uses a heat absorbing material to absorb heat generated by the battery cells of the battery pack assembly and transfer it out of the case of the assembly, thereby maintaining a lower temperature inside each battery pack and the entire battery assembly. Another partial solution is described in US Patent Application Publication No. 2019393574(A1) (Goeb et al.), which discloses the use of a thermally conductive gap filler composition including a thermally conductive filler material to cool the battery assembly. Summary of the Invention

[0005] Insulating / thermal protection barriers have been developed for use within battery assemblies (e.g., within the gap between adjacent battery cells) to slow or prevent such thermal runaway events, thereby protecting nearby structures (e.g., remaining battery cells, vehicle structures, building structures, etc.) and personnel. The barriers of the present invention can withstand the extremely high temperatures associated with battery hot spots and disassembled or otherwise damaged battery cells that cause thermal runaway events. When used between adjacent battery cells, the barriers of the present invention, due to their resistance to compression, can significantly slow or even stop a thermal runaway event, thereby helping to maintain a desired protective distance or gap between the affected battery cell and the adjacent battery cell. The desired protective distance or gap (i.e., gap size) between adjacent battery cells is a gap size that maintains a thickness of barrier material that sufficiently inhibits heat transfer between the adjacent battery cells to slow or prevent a thermal runaway event for a desired period of time (e.g., long enough to allow nearby personnel to escape harm, long enough to avoid nearby structures from being damaged, etc.). A thermal runaway event is considered to be prevented if the damage is contained within a battery assembly housing the battery cell and / or if at least a portion, a majority (greater than 50%), or all of the remaining battery cells in the battery assembly remain usable. The remaining battery cells are battery cells that are not the initial origin or initiating battery cells that may have caused the thermal runaway event but for the barrier of the present invention. Preferably, none of the remaining battery cells require replacement. Preferably, only the initial origin battery cells are damaged to the extent that they require replacement.

[0006] According to one aspect, the present disclosure relates to an insulating / thermal protective barrier operatively adapted (i.e., configured, dimensioned, and / or designed) to be disposed between adjacent battery cells of a battery assembly to provide thermal insulation and protection, the barrier comprising a cured silicone rubber foam layer including a plurality of toughening particles disposed within, and preferably uniformly disposed throughout, the silicone rubber foam layer in an amount sufficient to impart additional toughness to the silicone rubber foam layer such that a greater compressive force is required to compress the foam layer to a desired compressive value as compared to the same silicone rubber foam layer without the toughening particles.

[0007] The compressive behavior of these foams is an important property in terms of delaying or even preventing thermal runaway events. If a single battery cell is degraded or otherwise damaged, it can heat up and expand. This can significantly compress the thermal insulation / thermal protection barrier, especially the silicone rubber foam layer, and reduce the gap between the damaged cell and its neighbors. It has been found that the temperature of the neighboring cells is highly dependent on substantially maintaining the size of the gap (i.e., the distance between the neighboring cells) under operating conditions. It has been discovered that during such a thermal runaway event, the desired size of the gap can be significantly maintained, or at least, the reduction in the gap size can be significantly minimized as the foam's toughness increases. Thus, the development of tougher foams can help to delay or even prevent thermal runaway events.

[0008] In one embodiment, the silicone rubber foam layer is formed from a curable, foamable precursor of a silicone rubber foam comprising at least one organopolysiloxane compound A, at least one organohydrogenpolysiloxane compound B containing at least two or three hydrogen atoms per molecule, at least one hydroxyl-containing compound C, an effective amount of a curing catalyst D (e.g., a platinum-based curing catalyst), and a plurality of toughening particles disposed within the silicone rubber foam layer in an amount sufficient to cause the silicone rubber foam layer to exhibit a compression value of about 50% or less when subjected to a compressive force of greater than 100 kPa.

[0009] According to one aspect, the present disclosure provides a silicone rubber foam layer, comprising: providing a substrate; providing a first solid film and applying it onto the substrate; providing a coating tool having an upstream side and a downstream side and offset from the substrate to form a gap perpendicular to a surface of the substrate; moving the first solid film in a downstream direction relative to the coating tool; providing a curable and foamable precursor of a silicone rubber foam onto the upstream side of the coating tool and coating the silicone rubber foam precursor as a layer through the gap onto the substrate with the first solid film; providing a second solid film and applying the second solid film along the upstream side of the coating tool such that the first solid film and the second solid film are applied simultaneously with the formation of the layer of silicone rubber foam precursor; foaming or allowing to foam the silicone rubber foam precursor; and curing or allowing to cure the layer of silicone rubber foam precursor to form a silicone rubber foam layer. Optionally, the present invention relates to a silicone rubber foam layer obtained by a process comprising subjecting a layer of a silicone rubber foam precursor to a heat treatment, and optionally removing the first solid film and / or the second solid film from the silicone rubber foam layer.

[0010] According to another aspect, the present disclosure provides a process for producing a silicone rubber foam layer, comprising: Providing a substrate; Providing a first solid film and applying it onto a substrate; providing a coating tool having an upstream side and a downstream side, the coating tool being offset from the substrate to form a gap perpendicular to a surface of the substrate; moving the first solid film downstream relative to a coating tool; providing a curable and foamable precursor of a silicone rubber foam to an upstream side of a coating tool and coating the silicone rubber foam precursor as a layer through the gap onto the substrate with the first solid film; providing a second solid film and applying the second solid film along an upstream side of the coating tool such that the first solid film and the second solid film are applied simultaneously with the formation of the layer of silicone rubber foam precursor; foaming or allowing a silicone rubber foam precursor to foam; curing or allowing to cure the layer of silicone rubber foam precursor to form a silicone rubber foam layer; Optionally, subjecting the layer of silicone rubber foam precursor to a heat treatment; and and optionally removing the first solid film and / or the second solid film from the silicone rubber foam layer.

[0011] In yet another aspect, the present disclosure relates to the use of a silicone rubber foam layer as described above for industrial applications, particularly thermal management applications for the automotive industry. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of an exemplary coating apparatus and method for producing a silicone rubber foam layer according to an exemplary embodiment of the present disclosure. [Diagram 2] 1 is a schematic cross-sectional view of one exemplary coating tool useful in the present disclosure. [Diagram 3] 1 is a scanning electron microscope image of a cross section of an exemplary silicone rubber foam layer according to one embodiment of the present disclosure. [Figure 4] FIG. 1 illustrates an exemplary battery module assembly according to one aspect of the present disclosure. [Diagram 5] FIG. 1 illustrates an exemplary instrument used in hot side / cold side testing. [Figure 6]1 is a plot showing the variation of gap in a HCST with temperature. [Figure 7] 4 is a plot showing [Figure 8] 1 is a plot showing the results of HCST of Example 14A. [Figure 9] 1 is a plot showing the results of HCST of Example 25. [Figure 10] 1 is a plot showing the results of HCST of Example 21. [Figure 11] FIG. 1 shows a photograph of two layers of Example 21 after HCST (left: hot side, right: cold side). [Figure 12] FIG. 1 shows the results of thermogravimetric analysis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] According to one aspect, the present disclosure relates to an insulating / thermal protection barrier that includes a cured silicone rubber foam (preferably non-syntactic silicone rubber foam) layer and is operably adapted (i.e., configured, dimensioned, and / or designed) to be disposed to provide thermal insulation and protection within a battery assembly. More specifically, the insulating / thermal protection barrier is operably adapted to be disposed between adjacent battery cells in a battery assembly, thereby providing thermal insulation and protection to adjacent battery cells in the battery assembly. The silicone rubber foam layer includes a toughening material, such as a plurality of toughening particles disposed within the silicone rubber foam layer, preferably uniformly disposed throughout the silicone rubber foam layer, in an amount sufficient to impart additional toughness to the silicone rubber foam layer such that a greater compressive force is required to compress the foam layer to a desired compression value, as compared to the same silicone rubber foam layer without the toughening particles.

[0014] According to a more specific aspect, the present disclosure relates to a silicone rubber foam (preferably non-syntactic silicone rubber foam) layer formed from a curable and foamable precursor of silicone rubber foam including at least one organopolysiloxane compound A, at least one organohydrogenpolysiloxane compound B containing at least two or three hydrogen atoms per molecule, at least one hydroxyl-containing compound C, an effective amount of a curing catalyst D (e.g., a platinum-based curing catalyst), and a plurality of toughening particles disposed within the silicone rubber foam layer in an amount sufficient to cause the silicone rubber foam layer to exhibit desired compressive properties.

[0015] Exemplary toughening filler materials include cured particles made from the following materials: aluminum trihydroxide (ATH), magnesium hydroxide (MDH), calcium carbonate, mineral and other ceramic fibers, titanium dioxide (e.g., pyrogenic titanium dioxide), and any combination or mixture thereof. These toughening particles may be surface-treated and have low water absorption. Preferably, the toughening particles exhibit other desirable properties, such as any one or combination of silicone foam precursor viscosity enhancers, relatively low cost, endothermic, and flame retardant (e.g., particles such as aluminum trihydroxide (ATH), magnesium hydroxide (MDH), and calcium carbonate). Other desirable particle properties include structural reinforcement of the foam matrix, including after the silicone rubber has undergone a ceramification process (i.e., after the silicone has been exposed to high temperatures and converted into a silica-based ceramic).

[0016] Exemplary Barrier Embodiments 1. An insulating / thermal protection barrier operably adapted to be disposed between adjacent battery cells of a battery pack or module (e.g., for use on one side of cylindrical battery cells or prismatic or pouch-type battery cells), the insulating / thermal protection barrier comprising a cured silicone rubber foam (preferably non-syntactic silicone rubber foam) layer having at least one major surface or opposing major surfaces, and at least one optional solid film, the solid film disposed to cover at least one major surface or both opposing major surfaces of the silicone rubber foam layer (e.g., the foam layer can be sandwiched between two portions of a folded solid film or between a first solid film and a second solid film), the silicone rubber foam layer comprising a plurality of toughening particles disposed within the silicone rubber foam layer in an amount sufficient to impart additional toughness to the silicone rubber foam layer such that a greater compressive force is required to compress the foam layer to a desired compression value compared to the same silicone rubber foam layer without the toughening particles. 2. The silicone rubber foam layer is at least one organopolysiloxane compound A; at least one organohydrogenpolysiloxane compound B containing at least 2 or 3 hydrogen atoms per molecule; at least one hydroxyl-containing compound C; 13. The insulating / thermal protective barrier of embodiment 1, formed from a curable and foamable precursor of a silicone rubber foam comprising an effective amount of a curing catalyst D (e.g., a platinum-based curing catalyst). 3. The insulating / thermal protective barrier of embodiment 1 or 2, wherein a plurality of toughening particles are uniformly disposed throughout the silicone rubber foam layer. 4. The insulating / thermal protection barrier of any one of embodiments 1-3, wherein the plurality of toughening particles is in an amount sufficient to cause the silicone rubber foam layer to exhibit a compression value of about 30%, 35%, 40%, 45%, or 50% or less when subjected to a compressive force of at least 100 kPa, 150 kPa, 200 kPa, 250 kPa, 300 kPa, 350 kPa, 400 kPa, 450 kPa, or 500 kPa. 5. The insulation / thermal protection barrier of any one of embodiments 1-4, wherein the plurality of toughening particles is in an amount sufficient to cause the silicone rubber foam layer to exhibit a compression value of 50% or less when subjected to a compressive force of greater than 100 kPa. 6. The insulating / thermal protective barrier of any one of the preceding embodiments, wherein the amount of toughening particles is in the range of about 10% to about 60% by weight or less, or about 5% to about 30% by volume or less. 7. The insulating / thermal protective barrier of any one of the preceding embodiments, wherein the amount of toughening particles is about 40% by weight, or about 20% by volume. 8. The insulation / thermal protection barrier of any one of embodiments 1-7, wherein the toughening particles are any one or combination of the following material particles: aluminum trihydroxide (ATH) particles, magnesium hydroxide (MDH) particles, calcium carbonate particles, titanium oxide particles, and mineral fibers. 9. The insulating / thermal protective barrier of any one of the preceding embodiments, wherein the toughening particles have a size (i.e., major axis dimension) ranging from about 0.5 μm or more to about 3, 5, or 10 μm or less. 10. The insulating / thermal protective barrier of any one of the preceding embodiments, wherein the toughening particles have a size (i.e., major axis dimension) of about 2.0 μm. 11. The thermal insulation / thermal protection barrier of any one of the preceding embodiments, wherein the toughening particles comprise non-metallic inorganic fibers (e.g., mineral fibers) having a length in the range of about 200 μm to about 1000 μm, or at least in the range of about 250 μm to about 750 μm. For example, it may be desirable for the fiber length to be about 500 μm. The fibers also have a diameter in the range of at least about 3.0 μm to about 6.0 μm. For example, it may be desirable for the fiber diameter to be about 4.5 μm. 12. The insulation / thermal protection barrier of any one of embodiments 1-11, wherein the amount of toughening particles is sufficient to cause the silicone rubber foam layer to exhibit a compression value of about 25, 30, 35, 40, 45, 50, 55, or 60% or less when subjected to a compressive force of greater than 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, or 1200 kPa. 13. The insulating / thermal protection barrier of any one of embodiments 1-12, wherein the silicone rubber foam layer exhibits a compression value of about 50% or less when subjected to a compressive force of at least 200 kPa. 14. The insulating / thermal protection barrier of any one of embodiments 1-13, wherein the silicone rubber foam layer exhibits a compression value of about 50% or less when subjected to a compressive force of more than 1200 kPa. 15. The insulating / thermal protection barrier of any one of embodiments 1-14, wherein the silicone rubber foam layer exhibits a compression value of about 30% or less when subjected to a compressive force of more than 200 kPa. 16. The insulating / thermal protection barrier of any one of the preceding embodiments, wherein the silicone rubber foam layer exhibits a compression value of about 30% or less when subjected to a compressive force of more than 400 kPa. 17. An insulating / thermal protection barrier as described in any one of embodiments 1 to 16, wherein the silicone rubber foam layer exhibits a compression value ranging from about 30% to a maximum of about 50% when subjected to a compressive force ranging from about 200 kPa to about 1000 kPa or less. 18. An insulating / thermal protection barrier as described in any one of embodiments 1 to 17, wherein the silicone rubber foam layer exhibits a compression value ranging from about 30% to a maximum of about 50% when subjected to a compressive force ranging from about 300 kPa to about 800 kPa or less. 19. The thermal insulation / thermal protection barrier according to any one of the embodiments 1-18, wherein the toughening particles, individually or together, exhibit any one or combination of properties selected from silicone foam precursor viscosity enhancer or thickener, foam matrix reinforcement, relatively low cost, heat absorption, and flame retardant. Particles made from materials such as aluminum trihydroxide (ATH), magnesium hydroxide (MDH), and calcium carbonate exhibit most or all of these properties. Particles made from relatively short ceramic reinforcing particles (e.g., mineral particles, etc.) can provide structural reinforcement for the foam matrix, including after the silicone rubber has undergone a ceramization process (i.e., after the silicone has been exposed to high temperatures and converted to a silica-based ceramic). Particles made from titanium dioxide (e.g., pyrogenic titanium dioxide) can contribute to thickening or increasing the viscosity of the silicone foam precursor. The toughening particles can be added to the silicone foam precursor Part A, Part B, both Part A and Part B, after Part A and Part B are mixed, or after all of the precursor components are combined. 20. A method of using an insulating / thermal protection barrier according to any one of embodiments 1-19 between adjacent battery cells of a battery assembly.

[0017] According to another aspect, the present disclosure provides a process for obtaining a silicone rubber (non-syntactic) foam layer, the process comprising: Providing a substrate; Providing a first solid film and applying it onto a substrate; providing a coating tool having an upstream side and a downstream side, the coating tool being offset from the substrate to form a gap (substantially) perpendicular to a surface of the substrate; moving the first solid film downstream relative to a coating tool; providing a curable and foamable precursor of a silicone rubber foam to an upstream side of a coating tool and coating the silicone rubber foam precursor as a layer through the gap onto the substrate with the first solid film; providing a second solid film and applying the second solid film (at least partially) along an upstream side of the coating tool such that the first solid film and the second solid film are applied (substantially) simultaneously with the formation of the (adjacent) layer of silicone rubber foam precursor; foaming or allowing to foam a silicone rubber foam precursor; curing or allowing to cure the layer of silicone rubber foam precursor to form a silicone rubber foam layer; Optionally, subjecting the layer of silicone rubber foam precursor to a heat treatment; and optionally removing the first solid film and / or the second solid film from the silicone rubber foam layer.

[0018] In the context of the present disclosure, it has surprisingly been found that the silicone rubber foam layer obtained by the method as described above provides excellent thermal insulation properties, excellent heat resistance and stability, excellent thermal insulation / thermal protection barrier performance (e.g., thermal runaway barrier performance in the context of many battery cell module applications), excellent compressibility, and low density properties even at temperatures and long-term exposure to heat up to 600°C. The described silicone rubber foam layer is further characterized by one or more of the following advantageous advantages: a) excellent cushioning performance for individual battery cells when used as a battery assembly; b) easy and cost-effective manufacturing method based on readily available starting materials and minimized manufacturing steps; c) simplicity and versatility of formulation; d) efficient curing without the need for any large energy input such as high temperature or actinic radiation; e) safe handling of the foam layer due to the absence of materials or products that have harmful effects on the human body; f) excellent processability and conversion properties into various forms, sizes and shapes; g) producible with relatively thin thickness; h) ready-to-use foam layer especially for thermal management applications; and i) ability to adhere to various substrates such as metal or polymer surfaces without the need for adhesion promoting processing steps or compositions.

[0019] In one advantageous aspect, the silicone rubber foam layers described herein further comprise excellent flame resistant properties and excellent resistance to surface cracking and surface brittleness, even after prolonged exposure to temperatures up to 600°C.

[0020] Without wishing to be bound by theory, it is believed that these superior properties and performance attributes are due in particular to the combination of the following technical features: a) the use of a curable and foamable precursor of a silicone rubber foam, b) the use of a coating tool, and c) a specific processing step consisting of providing a second solid film and applying the second solid film along the upstream side of the coating tool such that the first and second solid films are applied simultaneously with the formation of the layer of silicone rubber foam precursor, in particular before the foaming and curing steps are (substantially) initiated.

[0021] Without wishing to be bound by theory, it is believed that this combination of technical features, particularly the process in which the first solid film and the second solid film are applied simultaneously with the formation of the layer of the precursor of the silicone rubber foam, directly results in a silicone foam layer with an advantageous porous structure and foam morphology, which results in the beneficial characteristics and performance attributes detailed above. More specifically, it is believed that this combination of technical features allows the foaming process to be carried out in a relatively controlled manner, which allows the gas cavities (or foam cells) to expand in the thickness direction of the foam layer (i.e., in the direction perpendicular to the plane formed by the foam layer), so that the resulting gas cavities have an oblong shape in the thickness direction of the layer and are uniformly distributed in the resulting foam layer.

[0022] Thus, the silicone rubber foam layer of the present disclosure is suitable for use in various industrial applications, especially thermal management applications. The silicone rubber foam layer of the present disclosure is particularly suitable for thermal management applications in the automotive industry, especially as an insulation / thermal protection barrier (e.g., as a thermal runaway barrier between adjacent battery cells in an electric vehicle battery module). The silicone rubber foam layer described herein has thermal runaway barrier properties suitable for use as a spacer between adjacent battery cells, or suitable for use as a spacer in a rechargeable electric energy storage system such as a battery module, as well as suitable for use between such storage systems (e.g., adjacent battery modules). Advantageously, further, the silicone rubber foam layer of the present disclosure can be used in the manufacture of battery modules, especially electric vehicle battery modules and assemblies. In a beneficial aspect, the silicone rubber foam layer described herein is suitable for manual or automated handling and applications, especially high-speed robotic equipment, especially due to its excellent dimensional stability and handling properties. The silicone rubber foam layer described can also meet the most challenging fire safety regulatory standards due to its remarkable flammability and thermal stability properties.

[0023] In the context of this disclosure, the term "adjacent" is meant to indicate two structures (e.g., battery cells, battery modules, superimposed films or layers, etc.) that are immediately adjacent to each other, i.e., abutting each other. The terms top and bottom layer or film, respectively, are used herein to indicate the position of a layer or film relative to the surface of the substrate carrying such layer or film in the process of forming a silicone rubber foam layer. The direction in which the substrate moves is referred to herein as the downstream direction. The relative terms upstream and downstream refer to positions along the extension of the substrate.

[0024] A schematic diagram of an exemplary method for producing a silicone rubber foam layer and a coating apparatus suitable for use in the production method is shown in Figure 1. The coating apparatus 1 comprises a substrate 2, a coating tool 7 in the form of a coating knife, an unwind roll 11 and a take-up roll 12 for a first solid film 5, and an unwind roll 9 and a take-up roll 10 for a second solid film 6. The downstream direction 8 in which the substrate 2 with the first solid film 5 moves relative to the coating tool 7 is represented by an arrow with a corresponding reference number.

[0025] In a typical embodiment of the present disclosure, the curable and foamable precursor of silicone rubber foam 3 is provided on the upstream side of a coating tool 7, whereby the silicone rubber foam precursor 3 is coated through the gap as a layer on the substrate 2 with a first solid film 5. In FIG. 1, the curable and foamable precursor of silicone rubber foam 3 is represented as forming a so-called "rolling bead" on the upstream side of the coating tool 7. A second solid film 6 is applied (at least partially) along the upstream side of the coating tool 7, whereby the first solid film 5 and the second solid film 6 are applied simultaneously with the formation of the layer of silicone rubber foam precursor 3. The layer of silicone rubber foam precursor 3 can then be foamed and cured into a silicone rubber foam layer 4, which typically comprises the first solid film 5 on its bottom surface and the second solid film 6 on its top surface. Optionally, the layer of silicone rubber foam precursor 3 can be subjected to a heat treatment, typically in an oven (not shown). In an exemplary embodiment, foaming of the layer of silicone rubber foam precursor 3 results in silicone rubber foam layer 4, which has a greater thickness than the initial layer of silicone rubber foam precursor 3. After processing, first solid film 5 and / or second solid film 6 may be removed from silicone rubber foam layer 4.

[0026] The substrate for use herein is not particularly limited. Substrates suitable for use herein can be readily identified by those of skill in the art in light of the present disclosure.

[0027] In a typical embodiment of the present disclosure, the substrate for use herein is a temporary support that is used for manufacturing purposes and is removed after the silicone rubber foam layer is separated and foamed and cured. The substrate can be optionally provided with a surface treatment adapted to allow the silicone rubber foam layer to be cleanly removed from the substrate (through the first solid film). Advantageously, the substrate for providing the temporary support for use herein can be provided in the form of an endless belt. Alternatively, the substrate for use herein can be a non-moving (static) temporary support.

[0028] In one particular aspect of the present disclosure, the resulting silicone rubber foam layer after foaming and curing can be separated from the substrate and wound up, for example, on a roll.

[0029] According to one advantageous aspect of the present disclosure, the substrate for use herein comprises a material selected from the group consisting of polymers, metals, ceramics, composites, and any combination or mixture thereof.

[0030] The silicone rubber foam layer of the present disclosure is obtained by a method using a coating tool with an upstream side and a downstream side, the coating tool being offset from the substrate to form a gap perpendicular to the surface of the substrate.

[0031] The coating tool for use herein is not particularly limited. Any coating tool known in the art can be used in the context of the present disclosure. Coating tools suitable for use herein can be easily identified by those skilled in the art in light of the present disclosure.

[0032] Each of the coating tools useful in the present disclosure has an upstream side (or upstream face) and a downstream side (or downstream face). In a typical embodiment, the coating tools for use herein further comprise a bottom portion facing the surface of the substrate that receives the precursor of the silicone rubber foam. The gap is measured as the minimum distance between the bottom portion of the coating tool and the exposed surface of the substrate. The gap can be essentially uniform in the lateral direction (i.e., in the direction perpendicular to the downstream direction) or can vary continuously or discontinuously in the lateral direction, respectively. The gap between the coating tool and the surface of the substrate is typically adjusted to control the thickness of each coating, in conjunction with other parameters including, for example, the speed of the substrate in the downstream direction, the type of coating tool, the angle at which the coating tool is oriented relative to the normal direction of the substrate, and the type of substrate.

[0033] In one advantageous embodiment of the present disclosure, the gap formed by the coating tool from the substrate (coating tool gap) is in the range of 10-3000 micrometers, 50-2500 micrometers, 50-2000 micrometers, 50-1500 micrometers, 100-1500 micrometers, 100-1000 micrometers, 200-1000 micrometers, 200-800 micrometers, or even 200-600 micrometers.

[0034] Coating tools for use herein can be positioned substantially perpendicular to the surface of the substrate, or can be tilted such that the angle between the substrate surface and the downstream side (or downstream face) of the coating tool ranges from 50° to 130°, or even 80° to 100°. Coating tools useful in the present disclosure are typically solid and may be rigid or flexible. Coating tools for use herein can take a variety of shapes, forms and sizes depending on the intended application and expected properties of the silicone rubber foam layer.

[0035] In an advantageous embodiment, the coating tool for use herein comprises a material selected from the group consisting of polymers, metals, composites, glass, and any combination or mixture thereof. More advantageously, the coating tool for use herein comprises a material selected from the group consisting of metals, in particular aluminum, stainless steel, and any combination thereof. Flexible coating tools for use herein are typically relatively thin, in particular having a downstream thickness in the range of 0.1 mm to 0.75 mm. Rigid coating tools for use herein are usually at least 1 mm, or even at least 3 mm thick.

[0036] According to an exemplary embodiment of the present disclosure, the coating tool for use herein is selected from the group consisting of a coating knife, a coating blade, a coating roll, a coating roll blade, and any combination thereof.

[0037] In an advantageous embodiment, the coating tool for use herein is selected from the group of coating knives. It has been found in practice that the use of a coating tool in the form of a coating knife provides a more reproducible coating process and a better quality coating, which translates into a silicone rubber foam layer with advantageous properties.

[0038] According to another advantageous aspect, the cross-sectional profile of the bottom part of the longitudinal coating tool (in particular the coating knife) is designed so that the precursor layer is formed and excess precursor is removed. Typically, the cross-sectional profile of the bottom part, as presented by the laterally extending edge of the coating tool facing the substrate, is essentially planar, curved, concave or convex.

[0039] An exemplary coating tool in the form of a coating knife is represented diagrammatically in cross-section in FIG. 2, where the coating tool 7 comprises an upstream side 13 and a downstream side 14 .

[0040] The precursor of silicone rubber foam for use herein is not particularly limited, as long as it is curable and foamable.Any curable and foamable precursor of silicone rubber foam known in the art can be formally used in the context of the present disclosure.Suitable curable and foamable precursor of silicone rubber foam for use herein can be easily identified by those skilled in the art in light of the present disclosure.

[0041] According to an advantageous embodiment, the silicone rubber foam precursors for use herein are in-situ foamable compositions, which means that foaming of the precursor occurs without the need for any additional compounds, in particular external compounds.

[0042] According to another advantageous aspect, the foaming of the precursors of the silicone rubber foams for use herein is carried out using a gaseous compound, in particular hydrogen gas.

[0043] In a more advantageous embodiment, foaming of the silicone rubber foam precursors for use herein is carried out by either gas generation or gas injection.

[0044] According to a preferred embodiment, foaming of the silicone rubber foam precursors for use herein is carried out by gas generation, in particular by in-situ gas generation.

[0045] In an alternative, less advantageous aspect, the silicone rubber foam precursor for use herein further comprises an optional blowing agent.

[0046] According to an advantageous embodiment, the silicone rubber foam precursor for use herein is a two-part composition.Typically, the silicone rubber foam precursor may be selected from the group consisting of an addition curing type two-part silicone composition, a condensation curing type two-part silicone composition, and any combination or mixture thereof.

[0047] In another beneficial aspect of the present disclosure, the silicone rubber foam precursor for use herein comprises an organopolysiloxane composition.

[0048] In a preferred embodiment, the silicone rubber foam precursors for use herein comprise addition-curable two-part silicone compositions, particularly addition-curable two-part organopolysiloxane compositions.

[0049] Suitable addition-curable two-part organopolysiloxane compositions for use herein as silicone rubber foam precursors can be easily identified by those skilled in the art.Exemplary addition-curable two-part organopolysiloxane compositions for use herein are described, for example, in U.S. Pat. No. 4,593,049 (Bauman et al.).

[0050] According to a particularly advantageous aspect of the present disclosure, the silicone rubber foam precursor for use herein comprises: a) at least one organopolysiloxane compound A; b) at least one organohydrogenpolysiloxane compound B containing at least two, in particular at least three, hydrogen atoms per molecule; c) at least one hydroxyl-containing compound C; d) an effective amount of a curing catalyst D, particularly a platinum-based curing catalyst; e) optionally, a blowing agent.

[0051] In an exemplary embodiment, at least one organopolysiloxane compound A for use herein has the formula: [ka] [In the formula, R and R” are independently C1 to C 30 in particular R is an alkyl group selected from the group consisting of methyl, ethyl, propyl, trifluoropropyl, and phenyl, optionally R is a methyl group; R' is C1 to C20 in particular R' is selected from the group consisting of vinyl, allyl, hexenyl, decenyl, and tetradecenyl, more particularly R' is a vinyl group; R" is an alkyl group, in particular methyl, ethyl, propyl, trifluoropropyl, phenyl, in particular R" is a methyl group; n is an integer having a value in the range of 5 to 1000, particularly 5 to 100].

[0052] In another exemplary embodiment, the at least one hydroxyl-containing compound C for use herein is selected from the group consisting of alcohols, polyols, especially polyols having from 3 to 12 carbon atoms per molecule and having an average of at least 2 hydroxyl groups, silanols, silanol-containing organopolysiloxanes, silanol-containing silanes, water, and any combination or mixture thereof.

[0053] In yet another exemplary embodiment, the at least one hydroxyl-containing compound C for use herein is selected from the group consisting of silanol-containing organopolysiloxanes.

[0054] According to an advantageous aspect of the present disclosure, the silicone rubber foam layer of the present disclosure is obtained by a method in which a step of providing a curable and foamable precursor of silicone rubber foam to the upstream side of a coating tool is carried out immediately followed by a step of providing a second solid film and applying the second solid film along the upstream side of the coating tool such that the first solid film and the second solid film are applied (substantially) simultaneously with the formation of the (adjacent) layer of silicone rubber foam precursor.

[0055] According to another advantageous aspect of the present disclosure, the steps of foaming or allowing to foam the silicone rubber foam precursor and curing or allowing to cure the layer of silicone rubber foam precursor to form the silicone rubber foam layer are performed (substantially) simultaneously.

[0056] The solid film for use herein as the first and second solid film is not particularly limited.Any solid film known in the art can be formally used in the context of the present disclosure.The solid film suitable for use herein can be easily identified by those skilled in the art in light of the present disclosure.

[0057] According to one advantageous embodiment, the first solid film and / or the second solid film for use in the present disclosure are impermeable films, in particular impermeable flexible films. As used herein, the term "impermeable" is intended to refer to impermeability to liquids and gaseous compounds, in particular gaseous compounds.

[0058] According to another advantageous aspect of the present disclosure, the first solid film and / or the second solid film for use herein are selected from the group consisting of polymeric films, metallic films, composite films, and any combination thereof.

[0059] In a more advantageous aspect of the present disclosure, the first solid film and / or the second solid film for use herein are selected from the group consisting of polymer films, in particular polymer films comprising a polymer material selected from the group consisting of thermoplastic polymers.

[0060] In an even more advantageous aspect of the present disclosure, the first solid film and / or the second solid film for use herein are polymeric films, the polymeric material being selected from the group consisting of polyesters, polyethers, polyolefins, polyamides, polybenzimidazoles, polycarbonates, polyethersulfones, polyoxymethylenes, polyetherimides, polystyrenes, polyvinyl chlorides, and any mixtures or combinations thereof.

[0061] In a further advantageous embodiment of the present disclosure, the first solid film and / or the second solid film for use herein are polymeric films comprising a polymeric material selected from the group consisting of polyesters, polyolefins, polyetherimides, and any mixtures or combinations thereof.

[0062] In a particularly advantageous embodiment, the first solid film and / or the second solid film for use in the present disclosure are polymeric films comprising a polymeric material selected from the group consisting of polyesters, in particular polyethylene terephthalate.

[0063] According to an advantageous aspect of the present disclosure, the silicone rubber foam layer of the present disclosure is obtained by a method in which a first solid film is applied to a bottom surface of the layer of silicone rubber foam precursor and a second solid film is applied to a top (exposed) surface of the layer of silicone rubber foam precursor.

[0064] In an exemplary embodiment of the present disclosure, the first solid film and / or the second solid film directly contact the adjacent silicone rubber foam layer.

[0065] In another advantageous aspect of the present disclosure, the first major (top) surface and the second (opposite) major (bottom) surface of the silicone rubber foam layer, and / or the first solid film and / or the second solid film are (substantially) free of any adhesion promoting compositions or treatments, and in particular are free of priming compositions, adhesive compositions, and physical surface treatments.

[0066] In yet another advantageous aspect of the present disclosure, no intermediate layer of any kind is included between the first major (top) surface or the second (opposite) major (bottom) surface of the silicone rubber foam layer and the first solid film and / or the second solid film.

[0067] In an exemplary embodiment of the present disclosure, the first and second solid films conformably and smoothly contact the corresponding surfaces of the silicone rubber foam layer, thereby substantially avoiding (or at least substantially reducing) air entrapment between the solid films and the corresponding surfaces of the silicone rubber foam layer.

[0068] According to one advantageous embodiment, the silicone rubber foam layer of the present disclosure comprises gas cavities, in particular gas hydrogen cavities, air gas cavities, and any mixture thereof.

[0069] According to one advantageous embodiment, the silicone rubber foam layer of the present disclosure comprises gas cavities having a (substantially) elongated shape in the thickness direction of the layer (i.e., in the direction perpendicular to the plane formed by the foam layer).

[0070] According to a more advantageous embodiment, the gas cavities that may be present in the silicone rubber foam layer have an elongated elliptical shape in the thickness direction of the layer. An exemplary gas cavity having an elongated elliptical shape in the thickness direction of the layer is shown in Figure 3, which is a scanning electron microscope image of a cross section of an exemplary silicone rubber foam layer according to the present disclosure.

[0071] Advantageously further, the gas cavity for use herein is not surrounded by any ceramic or polymer shell (other than the surrounding silicone polymer matrix).

[0072] In one particular embodiment, gas cavities for use herein have an average size (in the largest dimension) of 150 micrometers or less, 120 micrometers or less, 100 micrometers or less, 80 micrometers or less, 60 micrometers or less, 50 micrometers or less, 40 micrometers or less, 30 micrometers or less, or even greater than 20 micrometers (as calculated from SEM micrographs).

[0073] In another particular embodiment, the gas cavities for use herein have an average size (in the largest dimension) of 5 micrometers to 3000 micrometers, 5 micrometers to 2000 micrometers, 10 micrometers to 1500 micrometers, 20 micrometers to 1500 micrometers, 20 micrometers to 1000 micrometers, 20 micrometers to 800 micrometers, 20 micrometers to 600 micrometers, 20 micrometers to 500 micrometers, or even 20 micrometers to 400 micrometers (as calculated from SEM micrographs).

[0074] According to an exemplary embodiment, the silicone rubber foam layer of the present disclosure is (substantially) free of hollow cavities selected from the group consisting of hollow microspheres, glass bubbles, expandable microspheres, particularly hydrocarbon-filled expandable microspheres, hollow inorganic particles, expanded inorganic particles, and any combination or mixture thereof.

[0075] The silicone rubber foam layer of the present disclosure may include additional (optional) ingredients or additives depending on the intended application.

[0076] In certain embodiments of the present disclosure, the silicone rubber foam layer may further comprise additives specifically selected from the group consisting of flame retardants, softeners, curing agents, filler materials, tackifiers, nucleating agents, colorants, pigments, preservatives, rheology modifiers, UV stabilizers, thixotropic agents, surface additives, flow additives, nanoparticles, antioxidants, reinforcing agents, toughening agents, silica particles, calcium carbonate, glass or synthetic fibers, thermal insulation particles, conductive particles, electrically insulating particles, and any combination or mixture thereof. Exemplary filler additives include aluminum trihydroxide (ATH), magnesium hydroxide (MDH), huntite-hydromagnesite, talc, clay, boron-based flame retardants, molybdenum compounds, tin compounds, antimony compounds, expandable graphite, gypsum, calcium carbonate, and any combination or mixture thereof. In certain embodiments of the present disclosure, these fillers may be surface treated and may have low water absorption.

[0077] In one advantageous embodiment, the silicone rubber foam layer further comprises a non-combustible (or non-burning) filler material. In a more advantageous embodiment, the non-combustible filler material for use herein is selected from the group of inorganic fibers, in particular from the group consisting of mineral fibers, mineral wool, silicate fibers, ceramic fibers, glass fibers, carbon fibers, graphite fibers, asbestos fibers, aramid fibers, and any combination or mixture.

[0078] According to a more advantageous embodiment, the non-combustible filler material for use herein is selected from the group consisting of mineral fibers, silicate fibers, ceramic fibers, asbestos fibers, aramid fibers, and any combination or mixture.

[0079] According to a particularly advantageous embodiment, the non-combustible filler material for use herein is selected from the group consisting of mineral fibers.In the context of the present disclosure, it has been surprisingly discovered that silicone rubber foams further comprising mineral fibers provide excellent heat resistance and thermal stability properties and improved resistance to surface cracking and surface brittleness, even after long-term exposure to temperatures up to 600°C.Without wishing to be bound by theory, it is believed that these advantageous characteristics are due in particular to the excellent compatibility of the surrounding silicone polymer matrix with the mineral fibers (especially silicate fibers), which are responsible for densifying and mechanically stabilizing the resulting matrix.

[0080] In certain embodiments, the non-flammable filler material for use herein is included in the silicone rubber foam in an amount ranging from 0.5% to 40% by weight, 1% to 30% by weight, 1% to 20% by weight, 1% to 10% by weight, 1% to 8% by weight, 2% to 8% by weight, 2% to 6% by weight, or even 3% to 6% by weight, based on the total weight of the silicone rubber foam precursor composition.

[0081] In another exemplary embodiment, the silicone rubber foam layer of the present disclosure is (substantially) free of thermally conductive fillers.

[0082] According to one advantageous embodiment of the present disclosure, the silicone rubber foam layer has a compressive strength of 500 kg / m2 as measured according to the method described in the experimental section. 3 Below 450kg / m 3 Below 400kg / m 3 Below 380kg / m 3 Below 350kg / m 3 Below 320kg / m 3 Below 300kg / m 3 Below 280kg / m 3 Below 250kg / m 3 Below 220kg / m 3 or even 200 kg / m 3 It has the following density:

[0083] According to another advantageous aspect of the present disclosure, the silicone rubber foam layer has a compressibility of 200 kg / m2 as measured according to the method described in the experimental section. 3 ~500kg / m 3 , 200kg / m 3 ~450kg / m 3 , 200kg / m 3 ~400kg / m 3 , 200kg / m 3 ~380kg / m 3 , 200kg / m 3 ~350kg / m 3 , 200kg / m 3 ~320kg / m 3 , 200kg / m 3 ~300kg / m 3 , 200kg / m 3 ~280kg / m 3 , or even 200 kg / m 3 ~250kg / m 3 It has a density in the range of

[0084] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer has a hardness greater than 10, greater than 15, greater than 20, greater than 25, or even greater than 30 (Shore 00).

[0085] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer has a hardness (Shore 00) ranging from 10-80, 10-70, 20-70, 25-60, 25-55, 30-55, 30-50, 30-45, or even 30-40.

[0086] The silicone rubber foam layer may have a compression value of 60% at a compression force of 250 kPa or less, 200 kPa or less, 150 kPa or less, or even 100 kPa or less, when measured according to the test methods described in the Experimental Section.

[0087] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer has a heat transfer time to 150° C. of greater than 20 seconds, greater than 40 seconds, greater than 60 seconds, greater than 80 seconds, greater than 100 seconds, greater than 120 seconds, greater than 140 seconds, greater than 150 seconds, greater than 160 seconds, greater than 170 seconds, or even greater than 180 seconds, as measured according to the test methods described in the Experimental Section.

[0088] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer has a heat transfer time to 150°C in the range of 20 seconds to 600 seconds, 40 seconds to 600 seconds, 60 seconds to 500 seconds, 100 seconds to 500 seconds, 120 seconds to 400 seconds, 140 seconds to 300 seconds, 160 seconds to 200 seconds, or even 160 seconds to 180 seconds, when measured according to the test method described in the Experimental Section.

[0089] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer has a thermal conductivity of 1 W / m·K or less, 0.8 W / m·K or less, 0.6 W / m·K or less, 0.5 W / m·K or less, 0.4 W / m·K or less, 0.3 W / m·K or less, 0.2 W / m·K or less, or even 0.1 W / m·K or less, when measured according to the test method described in the Experimental Section.

[0090] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer has a thermal conductivity in the range of 0.005 W / m·K to 1 W / m·K, 0.01 W / m·K to 1 W / m·K, 0.02 W / m·K to 1 W / m·K, or even 0.02 W / m·K to 0.8 W / m·K, when measured according to the test method described in the Experimental Section.

[0091] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer is (substantially) subjected to a ceramization process at a temperature of 500°C or less, 450°C or less, 400°C or less, 350°C or less, 300°C or less, or even 250°C or less.

[0092] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer is (substantially) subjected to a ceramification process at a temperature in the range of 200°C to 450°C, 200°C to 400°C, 200°C to 350°C, 250°C to 350°C, or even 250°C to 300°C.

[0093] In the context of the present disclosure, it has surprisingly been discovered that a silicone rubber foam layer having the ability to undergo a ceramization process, particularly at relatively low temperatures, provides excellent heat resistance and thermal stability properties.

[0094] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer has a V-0 classification when measured according to the UL-94 standard flammability test method.

[0095] In one advantageous embodiment, the silicone rubber foam layer of the present disclosure has a thickness of 6000 micrometers or less, 5000 micrometers or less, 4000 micrometers or less, 3000 micrometers or less, 2500 micrometers or less, 2000 micrometers or less, or even 1500 micrometers or less.

[0096] In another advantageous embodiment, the silicone rubber foam layer of the present disclosure has a thickness in the range of 100 micrometers to 6000 micrometers, 200 micrometers to 5000 micrometers, 300 micrometers to 5000 micrometers, 300 micrometers to 4500 micrometers, 300 micrometers to 4000 micrometers, 500 micrometers to 4000 micrometers, 500 micrometers to 3000 micrometers, 500 micrometers to 2500 micrometers, 500 micrometers to 2000 micrometers, 500 micrometers to 1500 micrometers, 800 micrometers to 1500 micrometers, or even 1000 micrometers to 1500 micrometers.

[0097] According to one particular aspect of the present disclosure, the silicone rubber foam layer may include a first solid film and / or a second solid film. In an alternative implementation, the silicone rubber foam layer may not include either a first solid film and / or a second solid film.

[0098] As will be apparent to one of ordinary skill in the art, the silicone rubber foam layer of the present disclosure may take on a variety of forms, shapes, and sizes depending on the intended application. Similarly, the silicone rubber foam layer of the present disclosure may be post-processed or converted as is conventional practice in the art.

[0099] According to one exemplary embodiment, the silicone rubber foam layer of the present disclosure may be in the form of a roll wound, particularly horizontally wound, around a core, with or without the first solid film and / or the second solid film.

[0100] According to one exemplary embodiment, the silicone rubber foam layer of the present disclosure may be cut into smaller pieces of various forms, shapes, and sizes.

[0101] According to another aspect, the present disclosure is a process for making a silicone rubber foam layer, the process comprising: Providing a substrate; Providing a first solid film and applying it onto a substrate; providing a coating tool having an upstream side and a downstream side, the coating tool being offset from the substrate to form a gap perpendicular to a surface of the substrate; moving the first solid film downstream relative to a coating tool; providing a curable and foamable precursor of a silicone rubber foam to an upstream side of a coating tool and coating the silicone rubber foam precursor as a layer through the gap onto the substrate with the first solid film; providing a second solid film and applying the second solid film along an upstream side of the coating tool such that the first solid film and the second solid film are applied simultaneously with the formation of the layer of silicone rubber foam precursor; foaming or allowing to foam a silicone rubber foam precursor; curing or allowing to cure the silicone rubber foam precursor to form a silicone rubber foam layer; Optionally, subjecting the layer of silicone rubber foam precursor to a heat treatment; and optionally removing the first solid film and / or the second solid film from the silicone rubber foam layer.

[0102] All of the specific preferred aspects, particularly relating to the substrate, first and second solid films, coating tool, gap, curable and foamable precursor of the silicone rubber foam, optional ingredients, and various processing steps described above in the context of the silicone rubber foam layer, are fully applicable to the method for producing a silicone rubber foam layer.

[0103] According to an advantageous aspect of the process of the present disclosure, a first solid film is applied to a bottom surface of the layer of silicone rubber foam precursor and a second solid film is applied to a top (exposed) surface of the layer of silicone rubber foam precursor.

[0104] According to another advantageous aspect of the method of the present disclosure, the step of providing a curable and foamable precursor of silicone rubber foam to the upstream side of the coating tool is performed immediately followed by a step of providing a second solid film and applying the second solid film along the upstream side of the coating tool such that the first solid film and the second solid film are applied (substantially) simultaneously with the formation of the (adjacent) layers of silicone rubber foam precursor.

[0105] According to yet another advantageous aspect of the process of the present disclosure, the steps of foaming or allowing to foam the silicone rubber foam precursor and curing or allowing to cure the layer of silicone rubber foam precursor to form the silicone rubber foam layer are performed (substantially) simultaneously.

[0106] According to yet another advantageous aspect of the present disclosure, the method is a continuous method, in which the curable and foamable precursor of the silicone rubber foam is continuously provided upstream of the coating tool, in particular from a continuous dispensing device.

[0107] According to yet another advantageous aspect of the present disclosure, the method is a discontinuous method, in which the curable and foamable precursor of the silicone rubber foam is provided discontinuously upstream of the coating tool, in particular from a discontinuous dispensing device.

[0108] In yet another advantageous embodiment of the method, the step of moving the substrate with the first solid film in a downstream direction relative to the coating tool is carried out at a speed (web speed) in the range of 0.1 m / min to 50 m / min, 0.1 m / min to 40 m / min, 0.1 m / min to 30 m / min, 0.1 m / min to 20 m / min, 0.1 m / min to 10 m / min, 0.1 m / min to 8 m / min, 0.1 m / min to 6 m / min, 0.1 m / min to 5 m / min, 0.2 m / min to 5 m / min, 0.2 m / min to 4 m / min, 0.3 m / min to 3 m / min, 0.3 m / min to 2 m / min, 0.4 m / min to 2 m / min, 0.4 m / min to 1 m / min, or even 0.5 m / min to 1 m / min.

[0109] In yet another advantageous embodiment of the method, the step of providing the curable and foamable precursor of the silicone rubber foam upstream of the coating tool is carried out at a throughput in the range of 0.5 kg / hr to 100 kg / hr, 0.5 kg / hr to 80 kg / hr, 0.5 kg / hr to 60 kg / hr, 0.5 kg / hr to 50 kg / hr, 0.5 kg / hr to 40 kg / hr, 0.5 kg / hr to 30 kg / hr, 0.5 kg / hr to 25 kg / hr, 0.5 kg / hr to 20 kg / hr, 0.5 kg / hr to 15 kg / hr, 1 kg / hr to 15 kg / hr, 1.5 kg / hr to 15 kg / hr, 1.5 kg / hr to 10 kg / hr, 2 kg / hr to 10 kg / hr, 2 kg / hr to 8 kg / hr, or even 2 kg / hr to 6 kg / hr.

[0110] In yet another advantageous embodiment of the method, the step of providing a curable and foamable precursor of silicone rubber foam upstream of the coating tool comprises providing a curable and foamable precursor of silicone rubber foam upstream of the coating tool in an amount of 10 g / m 2 ~5000g / m2 , 50g / m 2 ~5000g / m 2 , 50g / m 2 ~4000g / m 2 , 50g / m 2 ~3000g / m 2 , 100g / m 2 ~3000g / m 2 , 100g / m 2 ~2500g / m 2 , 150g / m 2 ~2500g / m 2 , 150g / m 2 ~2000g / m 2 , 150g / m 2 ~1500g / m 2 , 150g / m 2 ~1000g / m 2 , or even 200 g / m 2 ~1000g / m 2 Coating weights in the range of

[0111] In yet another advantageous embodiment of the method, the step of foaming or allowing to foam the silicone rubber foam precursor is carried out at a temperature of 100° C. or less, 90° C. or less, 80° C. or less, 70° C. or less, 60° C. or less, 50° C. or less, 40° C. or less, or even 30° C. or less.

[0112] Advantageously further, the step of foaming or allowing the silicone rubber foam precursor to foam is carried out at a temperature in the range of 15°C to 40°C, or even 20°C to 30°C.

[0113] Advantageously further, the step of foaming or enabling foaming of the silicone rubber foam precursor is carried out using a gaseous compound, in particular hydrogen.

[0114] According to another advantageous aspect of the method, the step of foaming or allowing the silicone rubber foam precursor to foam is carried out either by gas generation or by gas injection, in particular by gas generation.

[0115] According to yet another advantageous aspect of the method, the step of curing or allowing to cure the layer of silicone rubber foam precursor is carried out at a temperature of 60° C. or less, 50° C. or less, 40° C. or less, or even 30° C. or less.

[0116] Advantageously further, the step of curing or allowing to cure the layer of silicone rubber foam precursor is carried out at a temperature in the range of from 15°C to 40°C, or even from 20°C to 30°C.

[0117] Advantageously further, the step of curing or allowing to cure the layer of silicone rubber foam precursor is carried out at a temperature in the range of 40°C to 100°C, 50°C to 100°C, 60°C to 100°C, 60°C to 90°C, or even 70°C to 90°C.

[0118] In yet another advantageous embodiment, the curable precursor of the silicone rubber foam is curable at 23° C. to a percent cure of greater than 90%, greater than 95%, greater than 98%, or even greater than 99% after a cure time of 72 hours or less, 48 ​​hours or less, or even 24 hours or less.

[0119] In yet another advantageous aspect, the curable precursor of the silicone rubber foam is curable at 23° C. to a percent cure of greater than 90%, greater than 95%, greater than 98%, or even greater than 99% after a cure time of 180 minutes or less, 210 minutes or less, 180 minutes or less, 150 minutes or less, 120 minutes or less, 100 minutes or less, 90 minutes or less, 80 minutes or less, 70 minutes or less, 60 minutes or less, 50 minutes or less, 40 minutes or less, or even 30 minutes or less.

[0120] In yet another advantageous aspect of the method of the present disclosure, the silicone rubber foam precursor is as described above in the context of the silicone rubber foam layer.

[0121] According to another advantageous embodiment of the method, the silicone rubber foam precursor is a two-part composition, in particular an addition-curable two-part silicone composition, more particularly an addition-curable two-part organopolysiloxane composition, and the silicone rubber foam precursor is obtained by mixing the two parts of the two-part silicone composition according to a dynamic mixing process.

[0122] According to another advantageous embodiment of the method, the step of mixing the two parts of the two-part silicone composition is carried out in a dynamic mixing device. Advantageously, further, the step of mixing the two parts of the two-part silicone composition is carried out immediately prior to the step of providing a curable and foamable precursor of the silicone rubber foam to the upstream side of the coating tool.

[0123] In yet another advantageous embodiment of the method of the present disclosure, the first solid film and the second solid film are as described above in the context of the silicone rubber foam layer.

[0124] According to an advantageous embodiment, the method of the present disclosure is (substantially) free of any step consisting of applying any adhesion promoting or adhesive composition to the first and second (opposite) major surfaces of the silicone rubber foam layer and / or to the first solid film and / or to the second solid film.

[0125] According to another advantageous aspect, the method of the present disclosure is (substantially) free of any step consisting of (physically) treating the first and second (opposite) major surfaces of the silicone rubber foam layer and / or the first solid film and / or the second solid film to enhance their adhesive properties.

[0126] According to another aspect, the present disclosure is directed to an insulating / thermal protective barrier article comprising a silicone rubber foam layer as described above.

[0127] According to yet another aspect, the present disclosure relates to a rechargeable electrical energy storage system, and in particular a battery module, comprising the above-described insulating / thermal protective barrier article.

[0128] In yet another aspect, the present disclosure relates to a battery module comprising a plurality of battery cells separated from one another by gaps, and a silicone rubber foam layer as described above disposed in the gaps between the battery cells.

[0129] 4 illustrates an exemplary assembled battery module 15 according to one embodiment of the present disclosure, which includes a plurality of battery cells 16 separated from one another by gaps and a plurality of silicone rubber foam layers 17 disposed in the gaps between the battery cells 16. The battery module further includes a base plate 19 having a thermally conductive gap filler 18 disposed therein.

[0130] Suitable battery modules, battery subunits, and methods of manufacture thereof for use herein are described, for example, in EP 3352290(A1) (Goeb et al.), in particular Figures 1-3 and paragraphs

[0016] -

[0035] , the contents of which are hereby incorporated by reference in their entirety.

[0131] According to yet another aspect, the present disclosure provides a method for manufacturing a battery module, comprising: a) providing a plurality of battery cells separated from one another by gaps; and b) placing the silicone rubber foam layer in the gap between the battery cells.

[0132] According to yet another aspect, the present disclosure relates to the use of the above-mentioned silicone rubber foam layer for industrial applications, in particular for thermal management applications, more particularly in the automotive industry.

[0133] According to yet another aspect, the present disclosure relates to the use of the above-described silicone rubber foam layer as a thermal barrier, in particular as an insulating / thermal protective barrier.

[0134] In yet another aspect, the present disclosure relates to the use of the above-described silicone rubber foam layer as an insulating / thermal protection barrier, particularly a thermal runaway barrier, in rechargeable electrical energy storage systems, particularly in battery modules.

[0135] In yet another aspect, the present disclosure relates to the use of the silicone rubber foam layer described above as an insulating / thermal protection barrier spacer, particularly a thermal runaway barrier spacer, between multiple battery cells present in a rechargeable electrical energy storage system, particularly a battery module. EXAMPLES

[0136] The present disclosure is further illustrated by the following examples, which are merely for illustrative purposes and are not intended to limit the scope of the appended claims.

[0137] Test Method 1) Thermal stability test (600℃) The test was carried out in a muffle furnace at 600°C. Test pieces were cut from the sample sheets and placed in porcelain crucibles. The porcelain crucibles were then placed in the furnace at 600°C for 3 minutes, then removed and allowed to cool before being analyzed by microscopy. The weight loss (%) of the samples after 3 minutes at 600°C was calculated.

[0138] 2) Insulation test The tests were carried out in compression mode using a Zwick tension / compression testing machine.

[0139] The compression tester comprises two plates (dimensions: 65×80×20 mm W×L×H, made of Inconel® steel, insulated on the outside): a cold (23° C.) bottom plate with a thermocouple to record the temperature, and a top plate heated at a constant temperature of 600° C. At the start of the test, a heat shield was placed between the two plates. The sample was placed on the cold bottom plate and the heat shield was removed. The top plate was moved to a gap of 1000 micrometers between the two plates. The temperature rise of the cold plate cold plate is recorded over time. Specifically, the time in seconds for the cold plate to reach 150° C. was recorded.

[0140] 3) Thermal conductivity measurement The thermal conductivity of the cured compositions is measured using the flash analysis method on a Netzsch Hyperflash LFA467 (Netzsch, Selb, Germany) according to ASTM E1461 / DIN EN821 (2013). Samples with a thickness of 1 mm are prepared by coating the curable composition between two PET release liners with a knife coater and curing at room temperature. The samples are then carefully cut into 10 mm x 10 mm squares with a knife cutter to fit the sample holder. Before the measurements, both sides of the sample are coated with a thin layer of graphite (GRAPHIT33, Kontakt Chemie). For the measurements, the temperature of the top side of the sample is measured by an InSb IR detector after irradiating the bottom side with a pulse of light (xenon flash lamp, 230 V, duration of 20-30 microseconds). The diffusivity is then calculated from the fitting of the thermogram by using the Cowan method. Three measurements are performed for each sample at 23 °C. For each formulation, three samples are prepared and measured. Thermal conductivity is calculated from the thermal diffusivity, density, and specific heat capacity of each sample. The heat capacity (Cp) is calculated in Joules per gram per Kelvin using Netzsch-LFA Hyper Flash in combination with a standard sample (Polyceram). The density (d) is determined in grams per cubic centimeter based on the weight and geometric dimensions of the sample. Using these parameters, the thermal conductivity (L) is calculated in watts per meter per Kelvin according to L=a·d·Cp.

[0141] 4) Flammability test The test was carried out using the UL94 standard, i.e., standard for safety testing of flammability of plastic materials for equipment and appliance parts. The UL94 standard is a flammability standard for plastics published by Underwriters Laboratories, USA. This standard determines whether the material tends to extinguish or spread the flame when the test specimen ignites. The UL-94 standard is aligned with IEC 60707, 60695-11-10 and 60695-11-20 and ISO 9772 and 9773. The specimen size, a sheet of 75 mm x 150 mm, is exposed to a 2 cm, 50 W tirrel burner flame ignition source. The test specimen was placed vertically above the flame with the test flame hitting the bottom of the specimen. For each specimen, the time to extinguish was measured and a V rating was given. As shown in Table 1 below, the V rating is a measure of the time it takes for the sample to extinguish without burning through the top of the clamp or dropping molten material that ignites the cotton indicator.

[0142] [Table 1]

[0143] 5) Compression test Compression tests were carried out in compression mode using a Zwick tensile tester. The samples used in the examples had a diameter of 50.8 mm and a thickness of >1000 micrometers. Tests were carried out at room temperature (typically 23°C). The top plate of the compression tester was moved at a rate of 1 mm / min until a maximum force of 2 MPa was reached. The compression force required to reach the compression value was recorded (in kPa) or the compression value obtained from a given compression force was recorded. The compression force was plotted against the deformation of the sample.

[0144] 6) Coating weight The coating weight of the silicone rubber foam layer was measured using a 100 cm 2 The coating weight was then determined in g / m 2 was converted to.

[0145] 7) Thickness The thickness of the silicone rubber foam layer was measured using a thickness gauge.

[0146] 8) Density Density of silicone rubber foam layer (kg / m 3 unit) to the coating weight of the foam layer (kg / m 2 The thickness of the plate was calculated by dividing the thickness (in m) of the plate by its thickness (in m).

[0147] 9) SEM micrograph Silicone rubber foam images were obtained from SEM micrographs recorded with a tabletop microscope TM3030 available from Hitachi High-Tech Corporation.

[0148] 10) High temperature side / low temperature side test (HCST) The test was carried out in compression mode using a Zwick tension / compression tester. The compression tester is equipped with two plates: a cold (RT) bottom plate (552) with a thermocouple (554) to record the temperature and a heated top plate (555) with a constant temperature of 600°C. The top plate (555) is heated with an element (557). At the start of the test, a heat shield (558) is between the two plates. The sample is placed on the bottom cold plate, then the heat shield is removed and the top plate is moved to the desired gap between the two plates (here 1.0 mm) or the desired compression force and the temperature of the cold side begins to be recorded. See FIG. 5. Depending on the example, the compression force was 0.1 MPa, 0.5 MPa or 1.0 MPa. The compression force is applied via a cylinder (562) and the bottom plate (552) is supported by a cylinder (560).

[0149] raw materials: In the examples, the following raw materials were used:

[0150] DOWSIL 3-8209 and DOWSIL 3-8235 are two-part room temperature vulcanizable silicone rubber foam formulations commercially available under the trade name DOWSIL, obtained from Dow Chemical Company, Midland, MI, United States. The Dowsil 3-8209 used had a viscosity of 1.07 kg / cm 3 Density of agent A: 1.01kg / cm 3 0.01, 0.18, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 10.16, 11.14, 12.12, 13.16, 14.18, 15.18, 16.19, 17.19, 18.2

[0151] BLUESIL 3242 is a two-component foam commercially available under the trade name BLUESIL obtained from ELKEM (Olso, Norway).

[0152] Hostaphan RN 50 / 50 is a neat PET solid film obtained from Mitsubishi Polyester Film (Greer, SC. ​​United States).

[0153] CoatForce CF30 is a silicate fiber and CoatForce 50 is a mineral fiber, both available from Rockwool BV, The Netherlands.

[0154] Martinal OL-104LEO is finely divided aluminum trihydroxide (ATH) obtained from Martinswerk GmBH (Bergheim, Germany) available under the trade name Martinal OL-104LEO.

[0155] IMERSEAL 74S is a surface treated calcium carbonate available under the trade name IMERSEAL obtained from WhitChem (Staffordshire, United Kingdom).

[0156] Magnifin H-5 is fine magnesium hydroxide (MDH) with a d50 of 1.8 μm and was purchased from Martinswerk Huber Minerals.

[0157] Magnifin H-5A is a finely divided magnesium hydroxide (MDH) with a vinyl surface modification and a d50 of 1.8 μm and was purchased from Martinswerk Huber Minerals.

[0158] Aeroxide PF2 is a pyrogenic titanium dioxide with 2% iron dioxide obtained from Evonik.

[0159] AFI PU Foam is a polyurethane foam sheet having a thickness of approximately 2000 micrometers, commercially available as a flame retardant polymer foam, obtained from Aerofoam Industries (Lake Elsinore, Calif., United States). [Example]

[0160] General Handmade Preparation Method of Exemplary Silicone Rubber Foam Layers Containing Fillers (Examples 1-5): An exemplary homemade silicone rubber foam layer was prepared according to the following procedure.

[0161] The mineral fibers, specified in parts by weight (see Table 1), were added to each of the A and B parts of the silicone foam using a high speed mixer at a speed of 2500 RPM for 30 seconds in two increments.

[0162] The materials in the amounts of parts by weight specified in Table 7 were added to a 200 mL two-part cartridge system (200 mL F-system cartridge) manufactured by Adchem GmbH in a 1:1 volumetric mix ratio. The two-part silicone system was mixed by a static mixer (MFH10-18T) using a dispensing gun at 4 bar air pressure. After releasing 50 g of mixed silicone into the jar, the mixture was further homogenized by hand for 10 seconds using a wooden spatula. The mixture was then coated by a knife coater with a gap thickness of 350 micrometers between two layers of solid film Hostaphan, as depicted in FIG. 1. The resulting sheet began to expand, and the reaction was completed by placing the sheet in a forced air oven at 80° C. for 10 minutes. Thickness, coating weight, density, thermal conductivity, and compression tests were performed, and the results are also included in Table 1.

[0163] [Table 2]

[0164] General Handmade Preparation Method of Exemplary Filler-Containing Silicone Rubber Foam Layers (Examples 6-8): The same procedure was followed as described in Examples 1-5, except that another mineral fiber was included (the two-part composition was premixed with ATH before being added to the 200 mL cartridge). The resulting sheet also began to expand, and the reaction was completed by placing the sheet in a forced air oven at 40° C. for 10 minutes. The mixture was then coated using a knife coater between two layers of Hostaphan® 50 / 50 solid film at gap thicknesses of 350 micrometers (Example 6), 400 micrometers (Example 7), and 800 micrometers (Example 8), as shown in FIG. 1. Thickness, coating weight, density, thermal conductivity, and compression tests were performed. The results are included in Table 2 along with the amounts of Part A and Part B in parts by weight.

[0165] [Table 3]

[0166] General Homemade Preparation Method for Exemplary Silicone Rubber Foam Layers (Examples 1-8) and Comparative Examples CE1 and CE2: Parts A and B were weighed and mixed by hand along with the corresponding filler and toughening packages, then they were mixed in a Speedmixer at 2500 rpm for 30 seconds twice.

[0167] Silicone foam sheets were prepared according to the following procedure: Silicone precursors A and B of each example were filled into a 200mL two-part cartridge system (200mL F System cartridge) from Adchem with a volumetric mix ratio of 1:1. In process 1, the materials were kept at room temperature, whereas in process 2, the materials were cooled to 7°C before mixing. The two-part silicone system is mixed by a static mixer (MFH10-18T) using a dispensing gun at 6 bar air pressure. After releasing 65g of mixed silicone into the jar, the mixture is further homogenized by hand using a wooden spatula for 10 seconds. The mixture is then coated between two PET liners with a defined gap using a knife coater. The resulting sheet already starts to expand at room temperature, and the reaction is completed in 10 minutes in a forced air convection oven at 60°C. In process 1, the resulting sheet was immediately placed in the oven, whereas in process 2, the materials were kept at room temperature for 10 minutes.

[0168] [Table 4]

[0169] High temperature / low temperature test performance In the hot side / cold side test (HCST), the foam is heated to 600° C. on one side (hot side) and pressure is applied, which compresses the foam. The temperature is measured on the other side of the foam. Compression of the foam at a given pressure reduces the gap between the hot side and the cold side. To investigate the effect of gap size on the isolation performance of the foams of the present invention, foams with different thicknesses and compression behaviors were prepared (Examples 9-15).

[0170] HCST Experiments. Table 3 summarizes the foams used in these experiments. The initial gap size in the HCST, the applied pressure in the HCST, the cold side temperature obtained after 10 minutes in the HCST, the gap size and compression values ​​obtained after 10 minutes in the HCST (THCST=600°C) are summarized in Table 1. Additionally, the compression values ​​at the same pressures at room temperature obtained from the compression test method are given.

[0171] The gap size and cold side temperature were investigated after 10 minutes in HCST using samples from Table 3. Figure 6 shows the dependence of cold side temperature after 10 minutes of HCST from gap size after 10 minutes of HCST. The correlation between these values ​​is linear for the systems and experimental design space investigated, which means that the isolation performance increases with increasing gap retention in HCST. Higher gap retention can be achieved by increasing the toughness of the foam.

[0172] [Table 5]

[0173] [Table 6]

[0174] Foam toughness performance To understand how to increase the toughness of the foam, the effect of different fillers in the foam was evaluated. Table 3 summarizes the foams tested. Figure 7 shows the compression test results of the foams.

[0175] Examples 15-17 show the effect of increasing ATH (from 9.8% to 13.7% by volume) and CaCO3 (from 9.9% to 13.8% by volume) concentrations. The foam toughness increases with increasing filler concentration. Also, the foam density (0.36 g / mL to 0.5 g / mL) and coating weight (980 to 1167 g / m2) increase, but the foam thickness decreases as the filler loading increases at a given gap size.

[0176] Comparison of Examples 16, 18 and 14 shows the effect of increasing fiber concentration (from 0.7% to 2.8% by volume) at a constant filler level (parts by weight). The foam toughness increases with increasing fiber concentration. Compression tests were also performed using two layers of foam from Example 14A. The toughness of this structure is slightly lower compared to the single layer structure.

[0177] Example 19 corresponds to a foam with very high filler (14.8 vol.% ATH and 15 vol.% CaCO3) and fiber concentration (2.3 vol.%). The resulting foam is extremely tough and has a very high density of 0.75 g / mL. In particular, the viscosity of side A is very high, probably near the upper limit of processability by Process 3.

[0178] Example 20 corresponds to a foam with a thicker thickness of 6830 μm. Typically, the toughness of a foam decreases as the thickness increases. Although a thicker foam is produced in this example, the toughness of the foam remains high.

[0179] [Table 7]

[0180] Compression Curve Figure 8 shows the HCST results for Example 14A (2 layers). The temperature after 10 minutes was 156°C, which is a very encouraging result compared to other foams tested so far.

[0181] General homemade preparation method for exemplary silicone rubber foam layers and comparative examples CE1 and CE2: Parts A and B were weighed and mixed by hand along with the corresponding filler and toughening packages, then they were mixed in a Speedmixer at 2500 rpm for 30 seconds twice.

[0182] Silicone foam sheets were prepared according to the following procedure: Silicone precursors A and B of each example were filled into a 200mL two-part cartridge system (200mL F System cartridge) from Adchem with a volumetric mix ratio of 1:1. The two-part silicone system is mixed by a static mixer (MFH10-18T) using a dispensing gun at 6 bar air pressure. After releasing 70g of mixed silicone into the jar, the mixture is further homogenized by hand using a wooden spatula for 10 seconds. The mixture is then coated using a knife coater between two PET liners with a defined gap (here 650μm). The resulting sheet already starts to expand at room temperature, and the reaction is completed in 10 minutes in a forced air convection oven at 60°C.

[0183] Comparative Example Commercially available silicone foam formulations Dowsil 3-8235 and Dowsil 3-8209 (Comparative Example 1 and Comparative Example 2) coated as described herein. Dowsil 3-8235 parts A and B have very high viscosities (77000 and 91000 mPa.s, respectively), while Dowsil 3-8209 has very low viscosities (15000 and 15000 mPa.s, respectively). Comparative Example 1 resulted in a very homogeneous soft foam as seen in Table 1, while Comparative Example 2 resulted in a heterogeneous foam sheet with macroscopic cell domains. Both Comparative Examples 1 and 2 are very soft, which can be seen in the low compressive forces at 40, 50 and 60% deformation. Although they undergo a ceramization process at high temperatures, they are highly compressed under external stresses such as those occurring between battery cells. This high compressibility affects the insulating properties under constant pressure, as seen in the HCST at 600°C under 1 MPa stress. In the case of Comparative Example 1, when the foam is compressed under 1 MPa, it reaches 150° C. already after 60 seconds (Table 1).

[0184] Silicone foam filled with ATH and CaCO3 To tailor the compression behavior of the silicone foam, a toughening package was added to the low viscosity foam precursor Dowsil 8209. The addition of toughening fillers had the following effects on foam performance: Better and more uniform foam quality by increasing the viscosity of the foam precursor part Better flame retardancy Reduced internal stresses in the cured foam sheet (absence): e.g. very good dimensional stability Better ceramification of silicone foams at temperatures >250°C (i.e. conversion of silicone to silica-based ceramics) -Adjusting compression characteristics · Prevention of cracks, mechanical integrity of ceramified foam -Price reduction

[0185] When incorporating aluminum trihydrate (ATH), calcium carbonate and optionally ceramic fibers, the viscosity of the low-viscosity foam precursor Dowsil 3-8209 could be advantageously increased to obtain very homogeneous foam sheets (Examples 25 to 27). In Examples 26 and 27 (prophetic examples), a small amount of nano-TiO2 was further incorporated to increase the heat resistance of the silicone foam. The incorporation of these fillers advantageously increases their compressive properties: the foams became harder and were able to better withstand external compressive stresses: under a load of 0.5 MPa, the low-temperature side reached 150°C only after 385 seconds, which is a significant improvement over very soft foams such as Comparative Example 1 (Table 6).

[0186] [Table 8]

[0187] [Table 9]

[0188] FIG. 9 shows the HCST of the layer of Example 25 on the hot side at 600° C. under a pressure of 0.5 MPa.

[0189] Silicone foam filled with magnesium hydroxide and CaCO3 Another highly preferred flame retardant and smoke suppressant is magnesium dihydrate (MDH). In a 1:1 exchange for ATH (Example 21 vs. Example 25), the MDH filled precursor results in a tougher foam structure at the same filler loading. The density is also higher (0.42 vs. 0.32 kg / cm3). 3). Further increasing the filler amounts of MDH and CaCO3 results in a tougher foam structure. The advantage of the tougher foams compared to the very soft foams (Comparative Examples 1 and 2) is that they maintain a higher gap between the battery cells at a given compressive stress. This higher gap results in better thermal insulation properties, as can be seen in the two-layer HCST of Examples 21 and 22 under a compressive force of 1 MPa. For Example 21, 150°C is reached only after 387 seconds, and for Example 22, after 531 seconds. Example 24 is interesting in that the surface-modified MDH produces a very dense foam (0.57 kg / cm3). 3 )

[0190] Figure 10 shows the results of HCST of two layers of Example 21 under 1 MPa compression. Figure 11 shows a photograph of two layers of Example 21 after 17 minutes in contact with a 600°C hot plate (left: hot side, right: cold side).

[0191] From FIG. 11 it can be seen that the hot side has begun to undergo the ceramification process, while the cold side is still silicone rubber foam.

[0192] thermogravimetric analysis The ceramization process was also analyzed by thermogravimetric analysis (TGA) in N for Comparative Example 2 (neat silicone foam), Example 21 filled with MDH and CaCO3, and Example 25 filled with ATH and CaCO3.

[0193] From the TGA analysis in N2 shown in Figure 12, the MDH-filled foams begin to lose weight later than the ATH-filled foams. The weight loss observed at a temperature of about 725°C is associated with the thermal oxidation of calcium carbonate.

[0194] The addition of ultra-fine MDH or ATH and CaCO to the silicone foam precursor can enable any, more, or all of the following: Controlling the flowability of foam precursors to obtain optimal foam sheet quality with fine cell distribution and uniform thickness Adjusting the compression behavior of the foam sheet by adjusting the filler loading - The ability to produce very tough silicone foam sheets (without internal stress) with high dimensional stability of the foam sheet Effectively retard or prevent heat transfer when used as a cushioning material within a battery assembly (e.g., an electric vehicle or EV battery assembly). · To produce silicone foam sheets with exceptional thermal insulation properties at very high temperatures (>300℃) -Effectively reduce the price of expensive silicone materials by incorporating inexpensive fillers When ceramic fibers having short lengths are added (to provide reinforcement), the crack resistance during the ceramization process at high temperatures is greatly improved. Fibers having lengths of about 250 to 750 μm (e.g., about 500 μm) may be desirable.

[0195] Additional Disclosures

[0196] [Table 10]

[0197] Test Method: Compression Test Compression tests were performed in compression mode using a tensile tester (obtained from ZWICKROELL, Ulm, Germany). Samples had a diameter of 33 mm and a thickness of >1000 micrometers. Tests were performed at room temperature (typically 23° C.). The top plate of the compression tester was moved at a rate of 1 mm / min until a maximum force of 2 MPa was achieved. The compression forces (in kPa) required to reach compression values ​​of 30%, 40%, 50%, and / or 60% were recorded.

[0198] High temperature side / low temperature side test (HCST) In a 10 kN tensile testing machine (obtained from ZWICKROELL, Ulm, Germany), the upper metal platen (having a diameter of 90 x 70 mm) was heated to 600°C and the sample was placed on the lower metal platen with an embedded thermocouple set at 23°C. A heat shield was used to cover the sample to ensure that it remained at ambient temperature. The heat shield was then removed and the upper platen was lowered while the pressure was maintained at 1 MPa. The time taken to reach 150°C on the cold side, the gap thickness before and after the test, and the temperature (°C) on the cold side were recorded.

[0199] Viscosity test (flow curve) Viscosity tests were performed using a stress-controlled rheometer (Anton Paar, Austria, MCR 302). Samples were measured at room temperature (typically 23°C) using a parallel plate geometry with a diameter of 25 mm and a gap of 1 mm. A 0.5 s -1 After preconditioning the sample at a constant shear rate of 0.1 s and a recovery time of 300 s, the shear rate ramp was -1 From 100s -1 When the experiment was carried out, the measurement time per data point decreased logarithmically from 15 seconds to 0.5 seconds. -1 , 1s -1 and 10s -1 The shear rate dependent viscosity values ​​at are reported exemplarily.

[0200] Examples 28 to 34 Table 7 provides a summary of the foam and filler compositions (parts by weight) and identifies the process used for fabrication, as well as the thickness, coating weight, and density of the samples. These samples were subjected to compression testing, the results of which are shown in Table 7.

[0201] [Table 11]

[0202] [Table 12]

Claims

1. 1. A thermal insulation / thermal protection barrier operatively adapted to be disposed between adjacent battery cells of a battery pack or module, the thermal insulation / thermal protection barrier comprising: a cured silicone rubber non-syntactic foam layer having at least one major surface; and at least one optional solid film, the solid film disposed so as to cover the at least one major surface of the silicone rubber foam layer; and the silicone rubber foam layer comprising a plurality of toughening particles disposed within the silicone rubber foam layer in an amount sufficient to impart additional toughness to the silicone rubber foam layer such that a greater compressive force is required to compress the foam layer to a desired compressive value compared to the same silicone rubber foam layer without the toughening particles.

2. The silicone rubber foam layer is at least one organopolysiloxane compound A; at least one organohydrogenpolysiloxane compound B containing at least two or three hydrogen atoms per molecule; at least one hydroxyl-containing compound C; 10. The thermal insulation / protection barrier of claim 1 formed from a curable and foamable precursor of a silicone rubber foam comprising: an effective amount of a curing catalyst D;

3. 10. The thermal insulation / protection barrier of claim 1, wherein the amount of the toughening particles ranges from about 10% to about 60% by weight or from about 5% to about 30% by volume.

4. 10. The thermal insulation / protection barrier of claim 1, wherein the toughening particles are any one or combination of particles of a material selected from aluminum trihydroxide (ATH) particles, magnesium hydroxide (MDH) particles, calcium carbonate particles, titanium oxide particles, silicon oxide particles, and mineral fibers.

5. 10. The thermal insulation / protection barrier of claim 1, wherein the toughening particles have a size ranging from about 0.5 μm to about 10 μm.

6. 10. The thermal insulation / protection barrier of claim 1, wherein the toughening particles comprise non-metallic inorganic fibers (e.g., mineral fibers) having a length in the range of about 200 [mu]m to about 1000 [mu]m.

7. 10. The thermal insulation / protection barrier of claim 1, wherein the amount of toughening particles is sufficient to cause the silicone rubber foam layer to exhibit a compression value of about 60% or less when subjected to a compressive force of greater than 1200 kPa.

8. 10. The thermal insulation / protection barrier of claim 1, wherein the silicone rubber foam layer exhibits a compression value of about 30% or less when subjected to a compressive force of more than 200 kPa.

9. 10. The thermal insulation / protection barrier of claim 1, wherein the silicone rubber foam layer exhibits a compression value ranging from about 30% up to about 50% when subjected to a compressive force ranging from about 300 kPa to about 800 kPa or less.

10. 10. A method of using the thermal insulation / protection barrier of claim 1 between adjacent battery cells of a battery assembly.

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