Silicone rubber foam having heat insulation properties

Abstract

The present disclosure provides 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 the coating tool; providing a curable 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 adjacent layers of the 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 optionally removing the first solid film and / or the second solid film from the silicone rubber foam layer.

Description

Technical Field

[0001] The present disclosure generally relates to the field of polymer foams, and more specifically to the field of silicone rubber foam sheets having heat insulation properties. The present disclosure also relates to methods for manufacturing such silicone rubber foams and their use for industrial applications, particularly their use for thermal management applications in the automotive industry.

Background Art

[0002] The electrification of vehicles is currently one of the most significant trends in the automotive industry. This trend has made the development of electric vehicle (EV) batteries suitable as propulsion and energy storage devices powered by batteries a major focus in the automotive industry. EV 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 capacities. The trend in the development of EV batteries is towards increasing the energy density (kWh / kg) within the battery, enabling coverage of longer distances, and shortening the charging time of the battery.

[0003] Due to the high energy density of EV batteries and the high energy flow during battery charging or discharging, there is a risk of the occurrence of hot spots and thermal runaway events where heat generated by the decomposition of battery cells propagates very rapidly to adjacent cells. This chain reaction can lead to an explosion or spread of fire throughout the entire EV.

[0004] In that situation, the use of thermal management solutions has rapidly emerged as one way to reduce the temperature rise of battery assemblies. One partial solution is disclosed in U.S. Patent Application Publication No. 2007 / 0259258 (A1) (Buck), according to which the use of a heat-absorbing material absorbs the heat generated by the battery cells of a battery pack assembly, transfers heat out of the assembly's case, thereby maintaining a lower temperature inside each battery pack and the entire battery assembly. Another partial solution is described in U.S. Patent Application Publication No. 2019393574 (A1) (Goeb et al.), according to which the use of a thermally conductive gap filler composition containing a thermally conductive filler material is disclosed for cooling a battery assembly. SUMMARY OF THE INVENTION

[0005] According to one aspect, the present disclosure provides a silicone rubber foam layer, 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, offset from the substrate to form a gap in a direction perpendicular to the surface of the substrate, moving the first solid film in a downstream direction relative to the coating tool, providing a curable foaming precursor of the silicone rubber foam on the upstream side of the coating tool and coating the precursor of the silicone rubber foam as a layer through the gap onto the substrate having 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 the precursor of the silicone rubber foam, causing or enabling the precursor of the silicone rubber foam to foam, curing or enabling the curing of the layer of the precursor of the silicone rubber foam to form a silicone rubber foam layer, Optionally, subjecting a layer of a precursor of the silicone rubber foam to a heat treatment, and relates to a silicone rubber foam layer obtained by a method comprising, optionally, removing a first solid film and / or a second solid film from the silicone rubber foam layer.

[0006] According to another aspect, the present disclosure is a method for manufacturing 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 in a direction perpendicular to the surface of the substrate, moving the first solid film in a downstream direction relative to the coating tool, providing a curable foaming precursor of the silicone rubber foam on the upstream side of the coating tool and coating the precursor of the silicone rubber foam as a layer through the gap onto the substrate provided 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 the precursor of the silicone rubber foam, causing or enabling the precursor of the silicone rubber foam to foam, curing or enabling the curing of the layer of the precursor of the silicone rubber foam to form a silicone rubber foam layer, optionally, subjecting the layer of the precursor of the silicone rubber foam to a heat treatment, and optionally, removing the first solid film and / or the second solid film from the silicone rubber foam layer, and relates to a method for manufacturing a silicone rubber foam layer.

[0007] In yet another aspect, the present disclosure relates to the use of a silicone rubber foam layer as described above for industrial applications, particularly for thermal management applications in the automotive industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

[0009] According to a first aspect, the present disclosure is a silicone rubber (non-sintered) foam layer, 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, offset from the substrate and forming a gap in a direction (substantially) perpendicular to the surface of the substrate, moving the first solid film in a downstream direction with respect to the coating tool, providing a curable foaming precursor of the silicone rubber foam on the upstream side of the coating tool and coating the precursor of the silicone rubber foam as a layer through the gap onto the substrate provided with the first solid film, providing a second solid film and applying the second solid film (at least partially) 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 an (adjacent) layer of the precursor of the silicone rubber foam, causing the precursor of the silicone rubber foam to foam or enabling foaming, Curing or enabling the curing of a layer of a precursor of a silicone rubber foam to form a silicone rubber foam layer; Optionally, subjecting the layer of the precursor of the silicone rubber foam to a heat treatment; Optionally, removing a first solid film and / or a second solid film from the silicone rubber foam layer, relates to a silicone rubber (non-syntactic) foam layer obtainable by a method comprising.

[0010] In the context of the present disclosure, surprisingly, the silicone rubber foam layer obtained by the method as described above exhibits excellent heat insulation properties, excellent heat resistance and stability, excellent thermal runaway barrier performance, excellent compressibility, and low density characteristics even at temperatures up to 600 °C and under long-term exposure to heat. The described silicone rubber foam layer is further characterized by one or more of the following advantageous benefits: a) excellent cushioning performance for individual battery cells when used as a battery assembly; b) an easy and cost-effective manufacturing method based on readily available starting materials and minimized manufacturing processes; c) simplicity and versatility of formulation; d) being efficiently curable without the need for any large energy input such as high temperature or actinic radiation; e) safe handling of the foam layer by not using materials or products that have harmful effects on the human body; f) excellent processability and conversion characteristics into various forms, sizes, and shapes; g) being manufacturable with a relatively thin thickness; g) a foam layer that is immediately usable especially for thermal management applications; and g) being adherable to various substrates such as metal or polymer surfaces without the need for an adhesion promotion processing step or composition.

[0011] These are particularly unexpected findings since it was expected that heat insulation and heat stability could not be obtained in a compressible (soft) foam layer, especially a foam layer having a relatively thin thickness.

[0012] In one advantageous aspect, the silicone rubber foam layer described herein further comprises excellent flame resistance and excellent resistance to surface cracking and surface brittleness even after long-term exposure to a temperature of up to 600 °C.

[0013] While not wishing to be bound by theory, these excellent properties and performance attributes are believed to be due in particular to the following combination of technical features: a) the use of a curable foaming precursor of a silicone rubber foam, b) the use of a coating tool, and c) 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 a layer of the precursor of the silicone rubber foam, in particular before the foaming and curing steps are (substantially) initiated, which consists of a specific processing step.

[0014] While not wishing to be bound by theory, this combination of technical features, in particular the step in which the first solid film and the second solid film are applied simultaneously with the formation of a layer of the precursor of the silicone rubber foam, is believed to directly result in a silicone foam layer having an advantageous porous structure and foam morphology, which results in the beneficial features and performance attributes detailed above. More specifically, this combination of technical features enables the foaming process to be carried out in a relatively controlled manner, whereby gas cavities (or foam cells) can expand in the thickness direction of the foam layer (i.e., the direction perpendicular to the plane formed by the foam layer), whereby the resulting gas cavities are believed to have an oblong shape in the thickness direction of the layer and to be uniformly distributed in the resulting foam layer.

[0015] Accordingly, the silicone rubber foam layer of the present disclosure is suitable for use in various industrial applications, particularly in thermal management applications. The silicone rubber foam layer of the present disclosure is particularly suitable for thermal management applications in the automotive industry, particularly as a thermal barrier, more specifically as a thermal runaway barrier. The silicone rubber foam layer described herein is particularly suitable for use as a spacer having thermal runaway barrier properties in a rechargeable electrical energy storage system, particularly a battery module. Advantageously further, the silicone rubber foam layer of the present disclosure can be used in the manufacture of battery modules, particularly electric vehicle battery modules and assemblies. In a beneficial aspect, the silicone rubber foam layer described herein is particularly suitable for manual or automated handling and applications, particularly high-speed robotic equipment, due to its excellent dimensional stability and handling characteristics. The described silicone rubber foam layer can also meet the most difficult fire protection regulatory standards due to its significant flammability and thermal stability characteristics.

[0016] In the context of the present disclosure, the term "adjacent" means two overlapping films or layers that are immediately adjacent to each other, i.e., in contact with each other. The terms upper and lower layers or films are each used herein to indicate the position of such a layer or film relative to the surface of the substrate that supports the layer or film in the method of forming the 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 represent positions along the extension of the substrate.

[0017] A schematic view of an exemplary method for manufacturing a silicone rubber foam layer and a coating apparatus suitable for use in the manufacturing method is shown in FIG. 1. The coating apparatus 1 includes a substrate 2, a coating tool 7 in the form of a coating knife, an unwind roll 11 and a windup roll 12 for the first solid film 5, and an unwind roll 9 and a windup roll 10 for the second solid film 6. The downstream direction 8 in which the substrate 2 provided with the first solid film 5 moves relative to the coating tool 7 is represented by an arrow with a corresponding reference number.

[0018] In a typical embodiment of the present disclosure, the curable foaming precursor 3 of the silicone rubber foam is provided upstream of the coating tool 7, whereby the precursor 3 of the silicone rubber foam is coated as a layer through a gap onto the substrate 2 provided with the first solid film 5. In FIG. 1, the curable foaming precursor 3 of the silicone rubber foam is shown as forming a so-called "rolling bead" upstream of the coating tool 7. The 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 the precursor 3 of the silicone rubber foam. Thereafter, the layer of the precursor 3 of the silicone rubber foam can be foamed and cured into the 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 the precursor 3 of the silicone rubber foam can typically be subjected to a heat treatment in an oven (not shown). In a typical embodiment, the foaming of the layer of the precursor 3 of the silicone rubber foam results in the silicone rubber foam layer 4, which has a greater thickness than the initial layer of the precursor 3 of the silicone rubber foam. After processing, the first solid film 5 and / or the second solid film 6 can be removed from the silicone rubber foam layer 4.

[0019] The substrate for use herein is not particularly limited. Suitable substrates for use herein can be readily identified by those skilled in the art based on the present disclosure.

[0020] In typical embodiments of the present disclosure, the substrate for use herein is a temporary support that is used for manufacturing purposes, from which the silicone rubber foam layer is separated and removed after foaming and curing. The substrate can optionally be subjected to a surface treatment adapted to enable clean removal of the silicone rubber foam layer from the substrate (through the first solid film). Advantageously, the substrate for providing a temporary support for use herein can be provided in the form of an endless belt. Alternatively, the substrate for use herein can be a stationary (static) temporary support.

[0021] In a particular aspect of the present disclosure, the silicone rubber foam layer obtained after foaming and curing is separated from the substrate and can be wound onto a roll, for example.

[0022] According to an 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.

[0023] The silicone rubber foam layer of the present disclosure is obtained by a method using a coating tool having an upstream side and a downstream side. The coating tool is offset from the substrate to form a gap in a direction perpendicular to the surface of the substrate.

[0024] 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. A coating tool suitable for use herein can be readily identified by those skilled in the art in view of the present disclosure.

[0025] Each coating tool useful in the present disclosure has an upstream side (or upstream surface) and a downstream side (or downstream surface). In a typical embodiment, the coating tool for use herein further comprises a bottom portion facing the surface of a substrate that receives a precursor of a 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., perpendicular to the downstream direction) or can vary continuously or discontinuously in the lateral direction. 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 vertical direction of the substrate, and the type of substrate.

[0026] In one advantageous embodiment of the present disclosure, the gap (coating tool gap) formed by the coating tool from the substrate ranges from 10 to 3000 micrometers, 50 to 2500 micrometers, 50 to 2000 micrometers, 50 to 1500 micrometers, 100 to 1500 micrometers, 100 to 1000 micrometers, 200 to 1000 micrometers, 200 to 800 micrometers, or even 200 to 600 micrometers.

[0027] The coating tool for use herein can be disposed 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 surface) of the coating tool ranges from 50° to 130°, or even 80° to 100°. The coating tools useful in the present disclosure are typically solid and can be rigid or flexible. The coating tools for use herein can take on various shapes, forms, and sizes depending on the intended use and expected properties of the silicone rubber foam layer.

[0028] In an advantageous aspect, 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, particularly aluminum, stainless steel, and any combination thereof. The flexible coating tool for use herein is typically relatively thin, particularly having a downstream thickness in the range of 0.1 to 0.75 mm. The rigid coating tool for use herein is typically at least 1 mm thick, or even at least 3 mm thick.

[0029] According to an exemplary aspect of the present disclosure, the coating tool for use herein is selected from the group consisting of coating knives, coating blades, coating rolls, coating roll blades, and any combination thereof.

[0030] In an advantageous aspect, the coating tool for use herein is selected from the group of coating knives. 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 has actually been found to be converted into a silicone rubber foam layer with advantageous properties.

[0031] According to another advantageous aspect, the cross-sectional profile of the bottom portion of the longitudinal coating tool (particularly, the coating knife) is designed such that a precursor layer is formed and excess precursor is removed. Typically, the cross-sectional profile of the bottom portion, as indicated by the laterally extending edge where the coating tool faces the substrate, is essentially planar, curved, concave, or convex.

[0032] An exemplary coating tool in the form of a coating knife is schematically represented in the cross-sectional view of FIG. 2, and the coating tool 7 comprises an upstream side 13 and a downstream side 14.

[0033] The precursor of the 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 officially used in the context of the present disclosure. Suitable curable and foamable precursors of the silicone rubber foam for use herein can be readily identified by those skilled in the art based on the present disclosure.

[0034] According to an advantageous aspect, the precursor of the silicone rubber foam for use herein is an in-situ foamable composition, which means that the foaming of the precursor occurs without the need for any additional compound, especially an external compound.

[0035] According to another advantageous aspect, the foaming of the precursor of the silicone rubber foam for use herein is carried out using a gaseous compound, especially hydrogen gas.

[0036] In a more advantageous aspect, the foaming of the precursor of the silicone rubber foam for use herein is carried out either by gas generation or gas injection.

[0037] According to a preferred aspect, the foaming of the precursor of the silicone rubber foam for use herein is carried out by gas generation, especially in-situ gas generation.

[0038] In an alternative and less advantageous aspect, the precursor of the silicone rubber foam for use herein further comprises an optional blowing agent.

[0039] According to a beneficial aspect, the precursor of the silicone rubber foam for use herein is a two-component composition. Typically, the precursor of the silicone rubber foam can be selected from the group consisting of addition-curing two-component silicone compositions, condensation-curing two-component silicone compositions, and any combination or mixture thereof.

[0040] In another beneficial aspect of the present disclosure, the precursor of the silicone rubber foam for use herein comprises an organopolysiloxane composition.

[0041] In a preferred aspect, the precursor of the silicone rubber foam for use herein comprises an addition-curing two-component silicone composition, particularly an addition-curing two-component organopolysiloxane composition.

[0042] Suitable addition-curing two-component organopolysiloxane compositions for use herein as precursors of silicone rubber foams can be readily identified by those skilled in the art. Exemplary addition-curing two-component organopolysiloxane compositions for use herein are described, for example, in U.S. Patent No. 4,593,049 (Bauman et al.).

[0043] According to a particularly advantageous aspect of the present disclosure, the precursor of the silicone rubber foam for use herein is a) at least one organopolysiloxane compound A, and b) at least one organohydrogenpolysiloxane compound B containing at least two, particularly at least three hydrogen atoms per molecule, and c) at least one hydroxyl-containing compound C, and d) an effective amount of a curing catalyst D, particularly a platinum-based curing catalyst, and e) optionally, a blowing agent, and comprises.

[0044] In an exemplary aspect, at least one organopolysiloxane compound A for use herein has the following formula:

Chemical formula

[0045] In another exemplary embodiment, at least one hydroxyl-containing compound C for use herein is selected from the group consisting of alcohols, polyols, particularly polyols having 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.

[0046] In yet another exemplary embodiment, at least one hydroxyl-containing compound C for use herein is selected from the group consisting of silanol-containing organopolysiloxanes.

[0047] According to an advantageous aspect of the present disclosure, the silicone rubber foam layer of the present disclosure is provided with a second solid film immediately after the step of providing a curable foaming precursor of the silicone rubber foam on the upstream side of the coating tool, and the first solid film and the second solid film are applied substantially simultaneously with the formation of the (adjacent) layer of the precursor of the silicone rubber foam. It is obtained by a method in which a step of applying a second solid film along the upstream side of the coating tool is performed.

[0048] According to another advantageous aspect of the present disclosure, the step of foaming or enabling foaming of the precursor of the silicone rubber foam and the step of curing or enabling curing of the layer of the precursor of the silicone rubber foam to form a silicone rubber foam layer are (substantially) simultaneously performed.

[0049] The solid films for use in the present disclosure as the first and second solid films are not particularly limited. Any solid film known in the art can be officially used in the context of the present disclosure. Suitable solid films for use herein can be readily identified by those skilled in the art based on the present disclosure.

[0050] According to one advantageous aspect, the first solid film and / or the second solid film for use in the present disclosure is an impermeable film, particularly an impermeable flexible film. As used herein, the term "impermeable" is intended to refer to impermeability to liquid and gaseous compounds, particularly gaseous compounds.

[0051] According to another advantageous aspect of the present disclosure, the first solid film and / or the second solid film for use herein is selected from the group consisting of polymer films, metal films, composite films, and any combination thereof.

[0052] In a more advantageous aspect of the present disclosure, the first solid film and / or the second solid film for use herein is selected from the group consisting of polymer films, particularly polymer films comprising a polymer material selected from the group consisting of thermoplastic polymers.

[0053] In an even more advantageous aspect of the present disclosure, the first solid film and / or the second solid film for use herein is a polymer film, and the polymer material is selected from the group consisting of polyester, polyether, polyolefin, polyamide, polybenzimidazole, polycarbonate, polyethersulfone, polyoxymethylene, polyetherimide, polystyrene, polyvinyl chloride, and any mixture or combination thereof.

[0054] In a further advantageous aspect of the present disclosure, the first solid film and / or the second solid film for use herein is a polymer film comprising a polymer material selected from the group consisting of polyester, polyolefin, polyetherimide, and any mixture or combination thereof.

[0055] In a particularly advantageous aspect, the first solid film and / or the second solid film for use in the present disclosure is a polymer film comprising a polymer material selected from the group consisting of polyester, particularly polyethylene terephthalate.

[0056] 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 the first solid film is applied to the bottom surface of the layer of the precursor of the silicone rubber foam, and the second solid film is applied to the upper (exposed) surface of the layer of the precursor of the silicone rubber foam.

[0057] In a typical aspect of the present disclosure, the first solid film and / or the second solid film are in direct contact with the adjacent silicone rubber foam layer.

[0058] In another advantageous aspect of the present disclosure, the first major (upper) 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, do not (substantially) contain any adhesion promoting composition or treatment, particularly no priming composition, adhesive composition, and physical surface treatment.

[0059] In yet another advantageous aspect of the present disclosure, no intermediate layer of any kind is included between the first major (upper) 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.

[0060] In a typical aspect of the present disclosure, the first and second solid films smoothly contact the corresponding surfaces of the silicone rubber foam layer so as to fit exactly, thereby substantially avoiding (or at least substantially reducing) the inclusion of air between the solid film and the corresponding surfaces of the silicone rubber foam layer.

[0061] According to one advantageous aspect, the silicone rubber foam layer of the present disclosure includes gas cavities, particularly gas hydrogen cavities, air gas cavities, and any mixtures thereof.

[0062] According to one advantageous aspect, the silicone rubber foam layer of the present disclosure includes gas cavities having a (substantially) long shape in the layer thickness direction (i.e., in a direction perpendicular to the plane formed by the foam layer).

[0063] According to a more advantageous aspect, the gas cavities that may be present in the silicone rubber foam layer have an elongated elliptical shape in the layer thickness direction. An exemplary gas cavity having an elongated elliptical shape in the layer thickness direction is shown in FIG. 3, which is a scanning electron microscope image of a cross-section of an exemplary silicone rubber foam layer according to the present disclosure.

[0064] Advantageously further, the gas cavities for use herein are not surrounded by any ceramic or polymer shell (other than the surrounding silicone polymer matrix).

[0065] In one particular aspect, the gas cavities for use herein have an average size (of the maximum 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 more than 20 micrometers (when calculated from SEM micrographs).

[0066] In another specific embodiment, the gas cavities for use herein have an average size (of the maximum dimension) of 5 to 3000 micrometers, 5 to 2000 micrometers, 10 to 1500 micrometers, 20 to 1500 micrometers, 20 to 1000 micrometers, 20 to 800 micrometers, 20 to 600 micrometers, 20 to 500 micrometers, or even 20 to 400 micrometers (when calculated from SEM micrographs).

[0067] According to a typical embodiment, the silicone rubber foam layer of the present disclosure may (substantially) not contain 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.

[0068] According to another embodiment, the silicone rubber foam of the present disclosure may contain a density-reducing filler that can be selected from the group consisting of microspheres, particularly hollow microspheres, such as glass bubbles, expandable microspheres, particularly hydrocarbon-filled expandable microspheres, hollow inorganic particles, expanded inorganic particles, and any combination or mixture thereof.

[0069] The silicone rubber foam layer of the present disclosure may include additional (optional) components or additives depending on the intended use.

[0070] In certain embodiments of the present disclosure, the silicone rubber foam layer may further include additives specifically selected from the group consisting of flame retardants, softening agents, 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, heat insulating particles, carbon black, iron, copper, aluminum, nickel, silver, metallized glass, lead, zinc, and conductive particles such as alloys, electrical insulating particles, and any combination or mixture thereof. Exemplary filler additives include aluminum trihydroxide (ATH), magnesium hydroxide (MDH), hydrotalcite-magnesite, talc, clay, boron-based flame retardants, molybdenum compounds, tin compounds, antimony compounds, expandable graphite, gypsum, calcium carbonate, carbide fillers such as silicon carbide, metals such as aluminum flakes and steel flakes, metal oxides such as aluminum oxide, iron oxide, lead oxide, magnesium oxide, titanium oxide, zinc oxide, zirconium oxide, sulfates such as barium sulfate and calcium sulfate, sulfides, molybdenum disulfide, zinc disulfide, silicates, glass, aluminum silicate, calcium silicate, zirconium silicate, titanates, and any combination or mixture thereof. In certain embodiments of the present disclosure, these fillers may be surface-treated and may have a low water absorption rate. Preferred fillers are selected from aluminum trihydroxide (ATH), calcium carbonate, the fibers described herein, and any combination and mixture thereof. Preferably, the filler includes a combination of aluminum trihydroxide (ATH), calcium carbonate, and the fibers described herein.

[0071] In certain embodiments of the present disclosure, the fillers may be selected according to their particle shape. The particle shape can be sufficiently defined by its length, width, and thickness. The particle shape can be spherical, cubic, prismatic, rhombohedral, flake, or fibrous.

[0072] In certain embodiments of the present disclosure, the fillers can be selected according to their particle sizes. The particle size can be defined by d50 (50% of the particles are smaller than this value) that defines the average particle size of the particle size distribution.

[0073] In certain embodiments, the filler materials used herein included in the silicone rubber foam have a d50 of 50 micrometers or less, 40 micrometers or less, 30 micrometers or less, 20 micrometers or less, 10 micrometers or less, or even 5 micrometers or less.

[0074] In certain embodiments, the filler materials used herein have a d50 in the range of 0.005 - 50 micrometers, 0.05 - 40 micrometers, 0.5 - 20 micrometers, 0.1 - 10 micrometers, or even 0.5 - 5 micrometers. This can have the effect that, together with preventing undesirable sedimentation of the filler, optimal rheology control of the precursor part can be achieved. Also, good ceramization at temperatures higher than 500 °C can be achieved, particularly in combination with flame retardant filler materials such as aluminum trihydrate (ATH), calcium carbonate and / or magnesium hydroxide. Furthermore, better mechanical integrity of the materials as disclosed herein can be obtained after exposure to temperatures exceeding 500 °C.

[0075] In certain embodiments, the filler materials used herein are included in the silicone rubber foam in an amount in the range of 0.5 - 80 wt%, 5 - 80 wt%, 10 - 80 wt%, 15 - 80 wt%, 20 - 80 wt%, 21 - 80 wt% based on the total weight of the precursor composition of the silicone rubber foam.

[0076] In certain embodiments, the filler materials used herein do not react with the hydrogen-functional silicone polymer or are surface-functionalized accordingly.

[0077] In certain embodiments, the filler materials used herein are compatible with the hydrogen-functional silicone polymer.

[0078] In a more beneficial embodiment, the filler material for use herein is a combination of fillers having a d50 of less than 10 micrometers.

[0079] In a more beneficial embodiment, the silicone foam further contains a non-combustible material, preferably a fiber material selected from the group of inorganic fibers, particularly mineral fibers, mineral wool, silicate fibers, ceramic fibers, glass fibers, carbon fibers, graphite fibers, asbestos fibers, aramid fibers, and any combination or mixture thereof.

[0080] In 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 thereof.

[0081] In a particularly beneficial 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, surprisingly, it has been found that silicone rubber foams further containing mineral fibers provide excellent heat resistance and thermal stability properties and improved resistance to surface cracks and surface brittleness even after long-term exposure to temperatures up to 600 °C. Without wishing to be bound by theory, these beneficial features are thought to be due in particular to the excellent compatibility between the surrounding silicone polymer matrix and the mineral fibers (particularly silicate fibers), which is involved in densifying and mechanically stabilizing the resulting matrix.

[0082] In certain embodiments, the non-combustible filler material for use herein is included in the silicone rubber foam in an amount in the range of 0.5 to 40 wt%, 1 to 30 wt%, 1 to 20 wt%, 1 to 10 wt%, 1 to 8 wt%, 2 to 8 wt%, 2 to 6 wt%, or even 3 to 6 wt% based on the total weight of the precursor composition of the silicone rubber foam.

[0083] In another typical aspect, the silicone rubber foam layer of the present disclosure does not contain (substantially) thermally conductive fillers.

[0084] According to one advantageous aspect of the present disclosure, the silicone rubber foam layer has a density of 500 kg / m 3 or less, 450 kg / m 3 or less, 400 kg / m 3 or less, 380 kg / m 3 or less, 350 kg / m 3 or less, 320 kg / m 3 or less, 300 kg / m 3 or less, 280 kg / m 3 or less, 250 kg / m 3 or less, 220 kg / m 3 or even 200 kg / m 3 or less when measured according to the method described in the experimental section.

[0085] According to another advantageous aspect of the present disclosure, the silicone rubber foam layer has a density in the range of 200 - 500 kg / m 3 , 200 - 450 kg / m 3 , 200 - 400 kg / m 3 , 200 - 380 kg / m 3 , 200 - 350 kg / m 3 , 200 - 320 kg / m 3 , 200 - 300 kg / m 3 , 200 - 280 kg / m 3 , or even 200 - 250 kg / m 3 when measured according to the method described in the experimental section.

[0086] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer has a hardness (Shore 00) greater than 10, greater than 15, greater than 20, greater than 25, or even greater than 30.

[0087] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer has a hardness (Shore 00) in the range of 10 - 80, 10 - 70, 20 - 70, 25 - 60, 25 - 55, 30 - 55, 30 - 50, 30 - 45, or even 30 - 40.

[0088] According to yet another advantageous aspect of the present disclosure, when measured according to the test method described in the experimental section, the silicone rubber foam layer has a compression value of at least 40% or at least 60% with a compression force of 1750 kPa, 1500 kPa, 1250 kPa, 1000 kPa, 750 kPa, 500 kPa, 250 kPa or less, 200 kPa or less, 150 kPa or less, or even 100 kPa or less.

[0089] According to yet another advantageous aspect of the present disclosure, when measured according to the test method described in the experimental section, the silicone rubber foam layer has a heat transfer time to 150 °C of more than 20 seconds, more than 40 seconds, more than 60 seconds, more than 80 seconds, more than 100 seconds, more than 120 seconds, more than 140 seconds, more than 150 seconds, more than 160 seconds, more than 170 seconds, or even more than 180 seconds.

[0090] According to yet another advantageous aspect of the present disclosure, when measured according to the test method described in the experimental section, the silicone rubber foam layer has a heat transfer time to 150 °C in the range of 20 to 600 seconds, 40 to 600 seconds, 60 to 500 seconds, 100 to 500 seconds, 120 to 400 seconds, 140 to 300 seconds, 160 to 200 seconds, or even 160 to 180 seconds.

[0091] According to yet another advantageous aspect of the present disclosure, when measured according to the test method described in the experimental section, 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.

[0092] According to yet another advantageous aspect of the present disclosure, when measured according to the test method described in the experimental section, the silicone rubber foam layer has a thermal conductivity in the range of 0.005 to 1 W / m·K, 0.01 to 1 W / m·K, 0.02 to 1 W / m·K, or even 0.02 to 0.8 W / m·K.

[0093] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer undergoes the ceramization process (substantially) at a temperature of 500 °C or lower, 450 °C or lower, 400 °C or lower, 350 °C or lower, 300 °C or lower, or even 250 °C or lower.

[0094] According to yet another advantageous aspect of the present disclosure, the silicone rubber foam layer undergoes the ceramization process (substantially) 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.

[0095] In the context of the present disclosure, surprisingly, it has been discovered that a silicone rubber foam layer having the function of undergoing the ceramization process, particularly at a relatively low temperature, provides excellent heat resistance and thermal stability characteristics.

[0096] 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.

[0097] In one advantageous aspect, 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.

[0098] In another advantageous aspect, the silicone rubber foam layer of the present disclosure has a thickness in the range of 100 to 6000 micrometers, 200 to 5000 micrometers, 300 to 5000 micrometers, 300 to 4500 micrometers, 300 to 4000 micrometers, 500 to 4000 micrometers, 500 to 3000 micrometers, 500 to 2500 micrometers, 500 to 2000 micrometers, 500 to 1500 micrometers, 800 to 1500 micrometers, or even 1000 to 1500 micrometers.

[0099] According to one particular aspect of the present disclosure, the silicone rubber foam layer may comprise a first solid film and / or a second solid film. In an alternative implementation, the silicone rubber foam layer may not comprise either the first solid film or the second solid film.

[0100] As will be apparent to those skilled in the art, the silicone rubber foam layer of the present disclosure can take various forms, shapes, and sizes depending on the intended application. Similarly, the silicone rubber foam layer of the present disclosure can be post-processed or converted as is customary in the art.

[0101] According to one exemplary aspect, the silicone rubber foam layer of the present disclosure can take the form of a roll that is wound around a core, particularly a horizontally wound roll. The silicone rubber foam layer in the wound roll may or may not comprise a first solid film and / or a second solid film.

[0102] According to one exemplary aspect, the silicone rubber foam layer of the present disclosure can be cut into smaller pieces of various forms, shapes, and sizes.

[0103] According to another aspect, the present disclosure is a method for manufacturing 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, offset from the substrate and forming a gap in a direction perpendicular to the surface of the substrate, moving the first solid film in a downstream direction with respect to the coating tool, providing a curable foaming precursor of the silicone rubber foam on the upstream side of the coating tool and coating the precursor of the silicone rubber foam as a layer through the gap onto the substrate having the first solid film, Providing a second solid film and applying the second solid film along the upstream side of a coating tool such that the first solid film and the second solid film are applied simultaneously with the formation of a layer of a precursor of a silicone rubber foam; Foaming a precursor of a silicone rubber foam or enabling foaming; Curing or enabling curing of a precursor of a silicone rubber foam to form a silicone rubber foam layer; Optionally, subjecting a layer of a precursor of a silicone rubber foam to a heat treatment; Optionally, removing the first solid film and / or the second solid film from the silicone rubber foam layer, relates to a method for manufacturing a silicone rubber foam layer.

[0104] In particular, all specific preferred embodiments related to the various processing steps described above in the context of a substrate, the first and second solid films, a coating tool, a gap, a curable foaming precursor of a silicone rubber foam, optional components, and a silicone rubber foam layer are fully applicable to a method for manufacturing a silicone rubber foam layer.

[0105] According to an advantageous aspect of the process of the present disclosure, the first solid film is applied to the bottom surface of a layer of a precursor of a silicone rubber foam, and the second solid film is applied to the upper (exposed) surface of a layer of a precursor of a silicone rubber foam.

[0106] According to another advantageous aspect of the method of the present disclosure, immediately after the step of providing a curable foaming precursor of a silicone rubber foam to the upstream side of a coating tool is carried out, a second solid film is provided and the second solid film is applied 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 an (adjacent) layer of a precursor of a silicone rubber foam.

[0107] According to yet another advantageous aspect of the process of the present disclosure, the step of foaming the precursor of the silicone rubber foam or enabling foaming and the step of curing or enabling curing of the layer of the precursor of the silicone rubber foam to form a silicone rubber foam layer are carried out (substantially) simultaneously.

[0108] According to yet another advantageous aspect of the present disclosure, the method is a continuous method in which the curable and foaming precursor of the silicone rubber foam is continuously provided upstream of the coating tool, in particular from a continuous dispensing device.

[0109] According to yet another advantageous aspect of the present disclosure, the method is a discontinuous method in which the curable and foaming precursor of the silicone rubber foam is discontinuously provided upstream of the coating tool, in particular from a discontinuous dispensing device.

[0110] In yet another beneficial aspect of the method, the step of moving the substrate provided with the first solid film downstream with respect to the coating tool is carried out at a speed (web speed) in the range of 0.1 to 50 m / min, 0.1 to 40 m / min, 0.1 to 30 m / min, 0.1 to 20 m / min, 0.1 to 10 m / min, 0.1 to 8 m / min, 0.1 to 6 m / min, 0.1 to 5 m / min, 0.2 to 5 m / min, 0.2 to 4 m / min, 0.3 to 3 m / min, 0.3 to 2 m / min, 0.4 to 2 m / min, 0.4 to 1 m / min, or even 0.5 to 1 m / min.

[0111] In yet another beneficial aspect of the method, the step of providing the curable and foaming precursor of the silicone rubber foam upstream of the coating tool is carried out at a throughput in the range of 0.5 to 100 kg / h, 0.5 to 80 kg / h, 0.5 to 60 kg / h, 0.5 to 50 kg / h, 0.5 to 40 kg / h, 0.5 to 30 kg / h, 0.5 to 25 kg / h, 0.5 to 20 kg / h, 0.5 to 15 kg / h, 1 to 15 kg / h, 1.5 to 15 kg / h, 1.5 to 10 kg / h, 2 to 10 kg / h, 2 to 8 kg / h, or even 2 to 6 kg / h.

[0112] In yet another advantageous aspect of the method, the step of providing the curable foaming precursor of the silicone rubber foam on the upstream side of the coating tool is carried out at a coating weight in the range of 10 to 5000 g / m 2 , 50 to 5000 g / m 2 , 50 to 4000 g / m 2 , 50 to 3000 g / m 2 , 100 to 3000 g / m 2 , 100 to 2500 g / m 2 , 150 to 2500 g / m 2 , 150 to 2000 g / m 2 , 150 to 1500 g / m 2 , 150 to 1000 g / m 2 , or even 200 to 1000 g / m 2 .

[0113] In yet another advantageous aspect of the method, the step of foaming or enabling foaming of the precursor of the silicone rubber foam is carried out at a temperature of 100 °C or lower, 90 °C or lower, 80 °C or lower, 70 °C or lower, 60 °C or lower, 50 °C or lower, 40 °C or lower, or even 30 °C or lower.

[0114] Advantageously further, the step of foaming or enabling foaming of the precursor of the silicone rubber foam is carried out at a temperature in the range of 15 °C to 40 °C, or even 20 °C to 30 °C.

[0115] Advantageously, the step of foaming or enabling foaming of the precursor of the silicone rubber foam is carried out using a gaseous compound, in particular hydrogen.

[0116] According to another advantageous aspect of the method, the step of foaming or enabling foaming of the precursor of the silicone rubber foam is carried out by either gas generation or gas injection, in particular by gas generation.

[0117] According to yet another advantageous aspect of the method, the step of curing or enabling curing of the layer of the precursor of the silicone rubber foam is carried out at a temperature of 60 °C or lower, 50 °C or lower, 40 °C or lower, or even 30 °C or lower.

[0118] Advantageously, further, the step of curing or enabling curing of the layer of the precursor of the silicone rubber foam is carried out at a temperature in the range of 15°C to 40°C, or even 20°C to 30°C.

[0119] Advantageously, further, the step of curing or enabling curing of the layer of the precursor of the silicone rubber foam 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.

[0120] In yet another advantageous aspect, the curable precursor of the silicone rubber foam can be cured at 23°C with a cure percentage of more than 90%, more than 95%, more than 98%, or even more than 99% after a curing time of 72 hours or less, 48 hours or less, or even 24 hours or less.

[0121] In yet another advantageous aspect, the curable precursor of the silicone rubber foam can be cured at 23°C with a cure percentage of more than 90%, more than 95%, more than 98%, or even more than 99% after a curing 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.

[0122] In yet another advantageous aspect of the method of the present disclosure, the precursor of the silicone rubber foam is as described above in the context of the silicone rubber foam layer.

[0123] According to another beneficial aspect of the method, the precursor of the silicone rubber foam is a two-component composition, particularly an addition-curing two-component silicone composition, more specifically an addition-curing two-component organopolysiloxane composition, and the precursor of the silicone rubber foam is obtained by mixing the two components of the two-component silicone composition according to a dynamic mixing process.

[0124] According to another advantageous aspect of the method, the step of mixing the two components of the two-component silicone composition is carried out in a dynamic mixing device. Advantageously, further, the step of mixing the two components of the two-component silicone composition is carried out immediately before the step of providing the curable foaming precursor of the silicone rubber foam on the upstream side of the coating tool.

[0125] In yet another advantageous aspect 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.

[0126] According to an advantageous aspect, the method of the present disclosure (substantially) does not include any step consisting of applying any adhesion promoting composition or adhesive composition to the first major surface and the second (opposite) major surface of the silicone rubber foam layer and / or the first solid film and / or the second solid film.

[0127] According to another advantageous aspect, the method of the present disclosure (substantially) does not include any step consisting of (physically) treating the first major surface and the second (opposite) major surface of the silicone rubber foam layer and / or the first solid film and / or the second solid film to enhance their adhesion properties.

[0128] According to another aspect, the present disclosure is directed to a thermal barrier article comprising a silicone rubber foam layer as described above.

[0129] According to yet another aspect, the present disclosure relates to a rechargeable electrical energy storage system, in particular a battery module comprising a thermal barrier article as described above.

[0130] In yet another aspect, the present disclosure relates to a battery module comprising a plurality of battery cells separated from each other by gaps and a silicone rubber foam layer as described above disposed in the gaps between the battery cells.

[0131] FIG. 4 shows an exemplary assembled battery module 15 according to one aspect of the present disclosure, which includes a plurality of battery cells 16 separated from each other by gaps, and a plurality of silicone rubber foam layers 17 disposed in the gaps between the battery cells 16. The battery module is further provided with a base plate 19 in which a thermally conductive gap filler 18 is disposed.

[0132] Suitable battery modules, battery sub-units, and methods for their manufacture for use herein are described, for example, in European Patent No. 3352290 (A1) (Goeb et al.), particularly FIGS. 1-3 and paragraphs

[0016] -

[0035] , the content of which is hereby incorporated by reference in its entirety into this specification.

[0133] According to yet another aspect, the present disclosure is a method of manufacturing a battery module, comprising: a) providing a plurality of battery cells separated from each other by gaps; and b) disposing the silicone rubber foam layer as described above in the gaps between the battery cells.

[0134] According to yet another aspect, the present disclosure relates to the use of the silicone rubber foam layer described above for industrial applications, particularly for thermal management applications, and more particularly for use in the automotive industry.

[0135] According to yet another aspect, the present disclosure relates to the use of the silicone rubber foam layer described above as a thermal barrier, particularly as a thermal runaway barrier.

[0136] In yet another aspect, the present disclosure relates to the use of the silicone rubber foam layer described above as a thermal barrier, particularly as a thermal runaway barrier, in a rechargeable electrical energy storage system, particularly in a battery module.

[0137] In yet another aspect, the present disclosure relates to the use of the silicone rubber foam layer described above as a thermal barrier spacer, particularly a thermal runaway barrier spacer, between a plurality of battery cells present in a rechargeable electrical energy storage system, particularly a battery module.

Examples

[0138] The present disclosure will be further described by the following examples. These examples are for illustrative purposes only and are not intended to limit the scope of the appended claims.

[0139] Test methods 1) Thermal stability test (600 °C) This test was carried out in a muffle furnace at 600 °C. The test piece was cut from the sample sheet and placed in a porcelain crucible. Then, the porcelain crucible was placed in the furnace at 600 °C for 3 minutes, then taken out and analyzed by microscopy after cooling. The weight loss (%) of the sample after 3 minutes at 600 °C was calculated.

[0140] 2) Heat insulation test This test was carried out in compression mode using a tensile / compression testing machine manufactured by Zwick. The compression testing machine includes two plates (dimensions: W×L×H of 65×80×20 mm, made of Inconel® steel, with the outer surface insulated): a low-temperature (23 °C) bottom plate equipped with a thermocouple for recording temperature, and an upper 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 low-temperature bottom plate and the heat shield was removed. The upper plate was moved between the two plates to a gap of 1000 micrometers. The temperature rise of the low-temperature plate cold plate was recorded over time. Specifically, the time in seconds when the low-temperature plate reached 150 °C was recorded.

[0141] 3) Thermal conductivity measurement The thermal conductivity of the cured composition is measured using the flash analysis method with Netzsch Hyperflash LFA467 (Netzsch, Selb, Germany) in accordance with ASTM E1461 / DIN EN821 (2013). A sample with a thickness of 1 mm is prepared by coating the curable composition between two PET release liners with a knife coater and curing it at room temperature. Then, the sample is carefully cut into a 10 mm × 10 mm square using a knife cutter and fitted into the sample holder. Before measurement, both sides of the sample are coated with a thin layer of graphite (GRAPHIT33, Kontakt Chemie). In the measurement, after irradiating the bottom side with a light pulse (xenon flash lamp, 230 V, duration of 20 - 30 microseconds), the temperature on the upper side of the sample is measured by an InSb IR detector. Then, the diffusivity is calculated from the fitting of the thermogram using the Cowan method. Three measurements are performed for each sample at 23 °C. For each formulation, three samples are prepared and measured. The 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 specified 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 kelvin according to L = a·d·Cp.

[0142] Flammability test The test was carried out using the UL94 standard, i.e., the standard for the flammability safety test of plastic materials for devices and appliance parts. The UL94 standard is a plastic flammability standard published by Underwriters Laboratories in the United States. This standard determines whether the material tends to extinguish or spread the flame when the test piece ignites. The UL-94 standard is consistent with IEC 60707, 60695-11-10 and 60695-11-20, as well as ISO 9772 and 9773. A sample size of a 75 mm × 150 mm sheet was exposed to a 2 cm, 50 W tirrel burner flame ignition source. The test sample was placed vertically above the flame with the test flame hitting the bottom of the sample. For each sample, the time to extinction was measured and a V grade was assigned. As shown in Table 1 below, the V grade is a measure of the time to digestion in a state where the sample does not burn up to the upper part of the clamp or does not drop molten material that ignites the cotton indicator.

[0143]

Table 1

[0144] 4) Compression test The compression test was carried out in compression mode using a tensile testing machine made by Zwick. The sample has a diameter of 50.8 mm and a thickness of more than 1000 micrometers. The test was carried out at 23 °C. The upper plate of the compression testing machine was moved at a speed of 1 mm / min until a maximum force of 2 MPa was achieved. The compression force (in kPa) required to reach at least 40% and / or 60% of the compression value was recorded.

[0145] 5) Coating weight The coating weight of the silicone rubber foam layer was measured by weighing a 100 cm sample cut from the sample layer using a circle cutter. Then, the coating weight was converted to g / m. 2 2

[0146] 6) Thickness ​The thickness of the silicone rubber foam layer was measured using a thickness gauge.

[0147] 7) Density The density (kg / m 3 unit) of the silicone rubber foam layer was calculated by dividing the coating weight (kg / m 2 unit) of the foam layer by their thickness (m unit).

[0148] 8) SEM micrograph The silicone rubber foam images were obtained from SEM micrographs recorded with a tabletop microscope TM3030 available from Hitachi High-Tech Corporation.

[0149] Raw materials: In the examples, the following raw materials were used. DOWSIL 3-8209 and DOWSIL 3-8235 are two-component room-temperature curable silicone rubber foam formulations commercially available under the DOWSIL brand name from Dow Chemical Company (Midland, MI, United States). BLUESIL 3242 is a two-component foam commercially available under the BLUESIL brand name from ELKEM (Olso, Norway). Hostaphan RN 50 / 50 is a PET solid film obtained from Mitsubishi Polyester Film (Greer, SC, United States). CoatForce CF30 is a silicate fiber and CoatForce 50 is a mineral fiber, both obtained from Rockwool B.V., The Netherlands). Martinal OL-104LEO is a fine aluminum trihydroxide (ATH) having a d50 in the range of about 1.7 to about 2.1 micrometers, obtained from Martinswerk GmBH (Bergheim, Germany) available under the trade name Martinal OL-104LEO. IMERSEAL 74S is a surface-treated calcium carbonate available under the trade name IMERSEAL from WhitChem (Staffordshire, United Kingdom). AFI PU Foam is a polyurethane foam sheet with a thickness of approximately 2000 micrometers, commercially available as a flame-retardant polymer foam from Aerofoam Industries (Lake Elsinore, CA, United States).

[0150] Examples: General manual preparation method for exemplary silicone rubber foam layers (Examples 1 - 2 and 4 - 5) and Comparative Example CE - 1: An exemplary manual silicone rubber foam layer was prepared according to the following procedure.

[0151] Agent A and Agent B of DOWSIL 3 - 8235 were filled into a 200 mL two - component cartridge system manufactured by Adchem GmbH at a volume mixing ratio of 1:1 (200 mL F - system cartridge). The two - component silicone system was mixed by a static mixer (MFH10 - 18T) using a dispensing gun at an air pressure of 4 bar. After discharging 50 g of the mixed silicone into a jar, the mixture was further homogenized by hand for 10 seconds using a wooden spatula. Then, this mixture was coated with a knife coater between two layers of Hostaphan RN 50 / 50 solid film as shown in Figure 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.

[0152] The preparation of the exemplary silicone foam layer of Example 5 (containing mineral fibers) involved a pre - step of incorporating mineral fiber CF30 into each of Agent A and Agent B of the two - component formulation using a high - speed mixer at a speed of 1500 RPM for 120 seconds (a total of 5% by weight based on the weight of the entire formulation), and then filling the resulting formulation into a 200 mL two - component cartridge system.

[0153] The preparation of the silicone foam layer of Comparative Example CE-1 (including a single solid film) differed from the above general procedure in that the precursor mixture was coated with a knife coater onto only one layer of the Hostaphan RN 50 / 50 solid film.

[0154] General continuous preparation method of an exemplary silicone rubber foam layer (Example 3): Prepare an exemplary continuously produced silicone rubber foam layer according to the following procedure.

[0155] Agent A and Agent B of DOWSIL 3-8235 were filled into a specific cartridge system equipped with a dynamic mixing head (3M 05846 Pneumatic Dynamic Mixing System available from 3M). The cartridge had a dynamic mixing nozzle adapted to a volume mixing ratio of 1:1 and a system of 1:1 (the 3M 05847 dynamic mixing nozzle was also available from 3M). By applying a pressure of 400 kPa, the piston of the dispensing device extruded the material through a nozzle rotating at 2000 - 3000 rpm. The throughput was 3.5 kg / h. The continuous bead of the dynamically mixed material was applied between two layers of the Hostaphan RN 50 / 50 solid film and extruded through a knife coater with a 350 micrometer gap and an 18.5 cm width as shown in Figure 1. The web speed was 0.7 m / min.

[0156] Exemplary silicone rubber foam layers (Examples 1 - 5) and Comparative Example CE-1: An exemplary silicone rubber foam formulation is shown in Table 1, and all complementary processing parameters are specified.

[0157] [Table 2]

[0158] Density [Table 3]

[0159] Thermal stability performance

Table 4

[0160] Heat insulation performance

Table 5

[0161] Compression performance

Table 6

[0162] Reduction of surface cracking performance (microscopic observation) The reduction in surface cracking performance obtained while using a silicone rubber foam layer containing mineral fibers (Example 5) compared to the same silicone rubber foam layer without mineral fibers (Example 2) is evaluated by comparing the magnified microscopic images of the corresponding silicone rubber foam layer surfaces. The sample surface used for microscopic observation is from the above heat insulation performance test facing the hot plate.

[0163] The reduction in surface cracking performance obtained while using a silicone rubber foam layer containing mineral fibers compared to the same silicone rubber foam layer without mineral fibers is clearly evident from microscopic observation. The microscopic images show that the silicone rubber foam layer containing mineral fibers has a stable non-brittle surface with reduced cracks, while the surface of the silicone rubber foam layer without mineral fibers results in deeper and more significant cracks along with a brittle surface.

[0164] Combustibility performance

Table 7

[0165] General manual preparation method of an exemplary silicone rubber foam layer containing a filler (Examples 6 - 10): An exemplary manually prepared silicone rubber foam layer was prepared according to the following procedure.

[0166] Mineral fibers specified in parts by weight (see Table 7) were added to each of Agent A and Agent B of the silicone foam using a high - speed mixer at a speed of 1500 RPM for 120 seconds.

[0167] Materials in the amounts in 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 at a volume mixing ratio of 1:1. The two - part silicone - based system was mixed by a static mixer (MFH10 - 18T) using a dispensing gun at an air pressure of 4 bar. After discharging 50 g of the mixed silicone into a jar, the mixture was further homogenized by hand for 10 seconds using a wooden spatula. Then, as shown in Figure 1, this mixture was coated with a knife coater at a gap thickness of 350 micrometers between two layers of the solid film Hostaphan. The resulting sheet began to expand, and the reaction was completed by placing the sheet in an 80 °C forced - air oven for 10 minutes. Thickness, coating weight, density, thermal conductivity, and compression tests were carried out, and the results are also included in Table 7.

[0168] [Table 8]

[0169] General manual preparation method of an exemplary silicone rubber foam layer containing a filler (Example 11): The same procedure as described in Examples 6 - 10 was followed, except that different two - part silicone rubbers were used. Thickness, coating weight, density, thermal conductivity, and compression tests were carried out. The results are included in Table 8 together with the amounts of Agent A and Agent B in parts by weight.

[0170] [Table 9]

[0171] General manual preparation method of an exemplary silicone rubber foam layer containing a filler (Examples 12 - 14): The same procedure as described in Examples 6 - 10 was followed, except that another mineral fiber was included (ATH was pre - mixed before adding the two - part composition to the 200 mL cartridge). Also, the obtained sheet began to expand, and the reaction was completed by placing the sheet in a forced - air oven at 40 °C for 10 minutes. Then, as shown in Figure 1, the mixture was coated with a knife coater between two layers of Hostaphan RN 50 / 50 solid film with gap thicknesses of 350 micrometers (Example 12), 400 micrometers (Example 13), and 800 micrometers (Example 14). Thickness, coating weight, density, thermal conductivity, and compression tests were performed. The results are included in Table 8 along with the amounts of Agent A and Agent B in parts by weight.

[0172] [Table 10]

Claims

1. A method for manufacturing a silicone rubber foam layer, comprising: a) providing a substrate; b) providing a first solid film and applying it onto the substrate; c) providing a coating tool having an upstream side and a downstream side, offset from the substrate to form a gap in a direction perpendicular to the surface of the substrate; d) moving the first solid film in a downstream direction relative to the coating tool; e) providing a curable foaming precursor of the silicone rubber foam on the upstream side of the coating tool, and coating the precursor of the silicone rubber foam as a layer through the gap onto the substrate provided with the first solid film; f) 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 the precursor of the silicone rubber foam; g) foaming the precursor of the silicone rubber foam; h) curing the layer of the precursor of the silicone rubber foam to form the silicone rubber foam layer; i) optionally, subjecting the layer of the precursor of the silicone rubber foam to a heat treatment; j) optionally, removing the first solid film and / or the second solid film from the silicone rubber foam layer. A method for manufacturing a silicone rubber foam layer.

2. The method for manufacturing a foam layer according to claim 1, wherein the foaming of the precursor of the silicone rubber foam is carried out using a gaseous compound.

3. The precursor of the silicone rubber foam comprises: a) at least one organopolysiloxane compound A; b) at least one organohydrogenpolysiloxane compound B containing at least two 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. The method for manufacturing a foam layer according to claim 1 or 2.

4. The method for manufacturing a foam layer according to any one of claims 1 to 3, comprising gas cavities having a shape long in the thickness direction of the layer.

5. A method for manufacturing a thermal runaway barrier using a silicone rubber foam layer obtained by the method for manufacturing a silicone rubber foam layer according to claim 1.

Images