Filled silicone foam layer, compositions for their manufacture, and articles including the filled silicone foam layer

Abstract

The extremely thin filled polysiloxane foam layer is formed from a composition comprising a curable polysiloxane composition, including alkenyl-substituted polyorganosiloxanes, hydride-substituted polyorganosiloxanes, and a curing catalyst; a plurality of expanded polymer microspheres, the maximum size of which is smaller than the thickness of the foam material; and a filler composition, wherein the maximum size of each component of the filler composition is smaller than the thickness of the foam material, the filler composition comprising particulate ceramic filler, particulate calcium carbonate filler, or particulate aluminosilicate clay filler with a disc-shaped morphology, or particulate aluminosilicate clay filler with a hollow tubular morphology, particulate polymer silsesquioxane filler, or particulate methylphenyl MQ filler, or a plurality of glass microspheres, or particulate paraffin, or combinations thereof; wherein the curable filled composition has a viscosity of less than 400,000 centiskJ, or 100,000 to 350,000 centiskJ.

Description

Technical Field

[0001] This invention relates to a composition for manufacturing a filled polysiloxane foam layer, a cured filled polysiloxane foam layer manufactured from the composition, a method for manufacturing the same, and an article comprising the filled polysiloxane foam layer. Prior Technology

[0002] The need to reduce, absorb, and prevent shocks to portable electronic devices from external physical impacts or extreme temperatures is increasing, including smart devices, particularly those with organic light-emitting diode (OLED) and flexible OLED screens. The high demand for thinner portable electronics necessitates the development of thinner cushioning solutions. Impacts to the external design of electronic devices can damage the screen itself and / or its internal components. Thermal effects from the external environment or prolonged use of the device can affect the performance of existing cushioning products on the market due to their high glass transition temperatures, leading to reduced performance. Shocks or stresses can also occur in the form of device usage, where the screen's rollability, foldability, or flexibility introduces pressure points at bends, which must be mitigated to maintain display quality. Random and instantaneous contact between the screen and impact forces can result in cracks, dents, or material damage. Solutions at the micron level are required to mitigate the effects of shock and temperature, which imposes manufacturing and formulation limitations that are typically unsuitable for larger applications. Summary of the Invention

[0003] A composition for manufacturing a filled polysiloxane foam layer comprises a curable polysiloxane composition including an alkenyl-substituted polyorganosiloxane, a hydride-substituted polyorganosiloxane, and a curing catalyst; a plurality of expanded polymer microspheres having a maximum size smaller than the thickness of the foam material; and a filler composition, wherein the maximum size of each component of the filler composition is smaller than the thickness of the foam material, the filler composition comprising particulate ceramic filler, particulate calcium carbonate filler, or particulate aluminosilicate clay filler having a disc-shaped morphology, or particulate aluminosilicate clay filler having a hollow tubular morphology, particulate polymer silsesquioxane filler, or particulate methylphenyl MQ filler, or a plurality of glass microspheres, or particulate paraffin, or combinations thereof; wherein the curable filled composition has a viscosity of less than 400,000 centiskJ, or 100,000 to 350,000 centiskJ.

[0004] The filled polysiloxane foam layer contains a cured curable component and has a thickness of 20 to 300 micrometers.

[0005] This invention discloses articles comprising the filled polysiloxane foam layer, particularly for screens of electronic devices.

[0006] The above-described and other features are illustrated by the following detailed description and requests. Implementation

[0007] The inventors of this invention have developed an ultrathin filled polysiloxane foam layer with an excellent combination of impact and other properties, including low compressive flexural strength, low compression set, low water absorption, low glass transition temperature, and surface smoothness. This combination of properties is achieved through a foam layer comprising a polysiloxane, expanded polymer microspheres, and a specific filler composition. The polysiloxane provides at least low compressive flexural strength, low compression set, low water absorption, low glass transition temperature, and surface smoothness. The expanded polymer microspheres and the specific filler composition further contribute to the low compressive flexural strength and low water absorption, and also provide a crush zone that is highly effective against impact. This combination of properties makes the filled polysiloxane foam layer particularly suitable for electronic devices, especially ultrathin electronic devices.

[0008] In particular, the expanded polymer microspheres and filler composition are dispersed in a curable polysiloxane composition using a hydrosilicone curing composition to form a solid but porous polysiloxane sheet. Using polysiloxane as a matrix (network polymer) offers many advantages that meet current market demands, such as constant softness and physical properties across a wide range of temperature conditions. It also allows for higher filler loadings that are not achievable in systems such as polyurethane foams or blended polymers. In one state, polysiloxane may have non-reactive groups, such as phenyl groups, at the side positions of the siloxane chains. The expanded polymer microspheres and fillers in the polysiloxane foam layer are present at concentrations and combinations that promote optimal interaction with the polysiloxane chains, thereby allowing the extrusion zone to absorb as much impact as possible. Some fillers can be configured to make the shape and modulus easier to extrude.

[0009] The curable filled composition used to manufacture silicone foam layers further comprises, in addition to expanded polymer microspheres and specific filler compositions, a curable polysiloxane composition having curable alkenyl-substituted polysiloxanes, co-curable hydrogenated polysiloxanes, and a curing catalyst. The components of the curable polysiloxane composition are selected to provide a liquid curable polysiloxane composition that allows for the incorporation of expanded polymer microspheres and filler compositions and the formation of extremely thin layers.

[0010] The curable polysiloxane composition is further selected to be elastomeric to provide a polysiloxane foam layer with target compression-flexure properties, used, for example, as a material inserted between screen assemblies in electronic devices. The curable polysiloxane composition is further selected to provide a cured polysiloxane material that maintains its elastic performance after numerous compression-flexure cycles, for example, throughout the lifespan of the screen. This is a property reflected by the stress relaxation and compressive permanent deformation of the selected elastomer group. The consistent performance across a variety of temperature conditions due to the low glass transition of cured polysiloxane also provides an advantage in applications. Curable polysiloxane composition

[0011] To achieve the advantageous properties of polysiloxane foam layers, particularly the combination of stress relaxation, low compression set, and high durability, specific combinations of polysiloxane components are used, especially higher molecular weight alkenyl-substituted polysiloxanes, lower molecular weight alkenyl-substituted polysiloxanes, and hydrogenated polysiloxanes, as described in more detail below. The use of selective, low-viscosity, non-volatile polysiloxane copolymers allows for further adjustment of the viscosity of the curable polysiloxane composition (and therefore the curable filled composition), as well as the surface properties and texture of the cured polysiloxane layer. The relative amounts of each component in the curable polysiloxane composition can be adjusted to allow for customization of the composition viscosity, and thus the filler content, which can affect other properties of the curable polysiloxane foam layer. In particular, high-molecular-weight, low-ethylene-content, high-viscosity liquids (e.g., 80,000 to 150,000 centistokes (cSt)) alkenyl-substituted polydimethylsiloxanes provide the bulk for curable polysiloxane compositions, reducing overall crosslinking density and providing a more advantageously softer material, despite its high density due to filler content. Lower molecular weight alkenyl-substituted poly(methylphenyl)siloxanes exist to further improve impact properties. Unbound by theory, it is believed that the network resulting from the reaction of these two components provides the desired low water absorption, low compression set, and low glass transition temperature.

[0012] Suitable alkenyl-substituted polyorganosiloxanes are generally represented by the following chemical formulas: M aD bT cQ d, The subscripts a, b, c, and d are zero or positive integers, with the restriction that if subscripts a and b are both zero, then subscript c is greater than or equal to two; the chemical formula of M is R 3SiO 1 / 2; the chemical formula of D is R 2SiO 2 / 2; the chemical formula of T is R 2SiO 3 / 2; and the chemical formula of Q is SiO 4 / 2, wherein each R group independently represents hydrogen, terminally substituted C 1-6 alkenyl, substituted and unsubstituted monovalent hydrocarbon groups, each having one to forty, or 1 to 6 carbon atoms, with the restriction that at least one, preferably at least two, of the R groups is an alkenyl R group. Suitable alkenyl R groups include vinyl, propenyl, 1-butenyl, 1-pentenyl, and 1-hexenyl, with vinyl being particularly useful. The alkenyl group can be at the end of the molecular chain, at the side position of the molecular chain, or a combination of both. In one state, the alkenyl group is a terminal group, such as a vinyl group bonded at the end of the molecular chain, i.e., an alkenyl-terminated polyorganosiloxane.

[0013] When present, other silicon-bonded organic groups in alkenyl-substituted polyorganosiloxanes, exemplified by substituted and unsubstituted monovalent hydrocarbon groups, have from one to forty carbon atoms, such as: alkyl groups like methyl, ethyl, propyl, butyl, pentyl, and hexyl; aryl groups like phenyl, tolyl, and xylyl; aralkyl groups like benzyl and phenethyl; and halogenated alkyl groups like 3-chloropropyl and 3,3,3-trifluoropropyl. Methyl and phenyl are particularly useful. The concentration of phenyl groups present in alkenyl-substituted polyorganosiloxane chain resins is optimized to increase energy absorbed from shocks.

[0014] Alkenyl-containing polyorganosiloxanes can have straight-chain, partially branched straight-chain, branched, or network molecular structures, or mixtures of these structures. Examples of alkenyl-substituted polyorganosiloxanes include vinyl-terminated polydimethylsiloxanes; vinyl-terminated dimethylsiloxane-diphenylsiloxane copolymers; vinyl-terminated dimethylsiloxane-methylphenylsiloxane copolymers; vinyl-terminated dimethylsiloxane-methylphenylsiloxane-diphenylsiloxane copolymers; vinyl-terminated dimethylsiloxane-methylphenylsiloxane copolymers; vinyl-terminated dimethylsiloxane-methylphenylsiloxane copolymers; vinyl-terminated dimethylsiloxane-methylvinylsiloxane copolymers; vinyl-terminated methylvinylsiloxane-methylphenylsiloxane copolymers. Vinyl-terminated dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer; dimethylvinylsiloxy-terminated methylvinylpolysiloxane; dimethylvinylsiloxy-terminated methylvinylphenylsiloxane; dimethylvinylsiloxy-terminated dimethylvinylsiloxane-methylvinylsiloxane copolymer; dimethylvinylsiloxy-terminated dimethylsiloxane-methylvinylsiloxane copolymer; dimethylvinylsiloxy-terminated dimethylsiloxane-methylphenylsiloxane copolymer; dimethylvinylsiloxy-terminated dimethylsiloxane-diphenylsiloxane copolymer; or combinations thereof.

[0015] The curable polysiloxane composition is preferably a combination comprising at least two of the above-mentioned alkenyl-substituted polyorganosiloxanes, one having a higher molecular weight and the other a lower molecular weight. The relative amounts of each compound depend on its individual molecular weight and can therefore vary considerably. Similarly, the molecular weight of each compound can vary depending on its content and the desired properties of the cured polysiloxane. The lower molecular weight component can reduce the overall viscosity of the mixture, providing easier casting, coating, spreading, and various texturing methods, including casting onto a carrier. Alternatively, the lower molecular weight compound can be an alkenyl-terminated polydiorganosiloxane containing methyl and phenyl groups in its silicate backbone. In one state, the higher molecular weight alkenyl-substituted polydiorganosiloxane is vinyl-terminated polydimethylsiloxane, and the lower molecular weight alkenyl-substituted polydiorganosiloxane is vinyl-terminated dimethylsiloxane-diphenylsiloxane copolymer, vinyl-terminated dimethylsiloxane-methylphenylsiloxane copolymer, vinyl-terminated dimethylsiloxane-methylphenylsiloxane-diphenylsiloxane copolymer, or a combination thereof.

[0016] When two (or more) curable alkenyl-substituted polyorganosiloxanes are used to formulate curable polysiloxane compositions, their relative contents depend on the type and content of each component, as well as the desired properties of the cured silicone foam layer. Generally, a curable polysiloxane composition may contain 40 to 99 wt%, or 65 to 95 wt%, of a first, higher molecular weight curable polysiloxane composition, and 10 to 50 wt%, or 15 to 35 wt%, of a second, lower molecular weight polysiloxane composition, each based on the total weight of the curable polysiloxane composition.

[0017] Suitable polyorganosiloxanes, with at least two hydrogen atoms bonded to silicon per molecule, are generally represented by the following chemical formulas: M′ aD′ bT′ cQ′ d, Wherein, the subscripts a, b, c, and d are zero or positive integers, with the restriction that if subscripts a and b are both equal to zero, then subscript c is greater than or equal to two; the chemical formula of M′ is R 3SiO 1 / 2; the chemical formula of D′ is R 2SiO 2 / 2; the chemical formula of T′ is R 2SiO 3 / 2; and the chemical formula of Q′ is SiO 4 / 2, wherein each R group independently represents hydrogen, substituted and unsubstituted monovalent hydrocarbon groups, each having one to forty or one to six carbon atoms, with the restriction that at least two of the R groups are hydrogen atoms. Preferably, each R group of the polyorganosiloxane having at least two hydrogen atoms bonded to silicon per molecule is independently selected from hydrogen, methyl, ethyl, propyl, butyl, pentyl, hexyl, aryl, phenyl, tolyl, xylyl, aralkyl, benzyl, phenethyl, alkyl halide, 3-chloropropyl, 3,3,3-trifluoropropyl, or combinations thereof. Methyl and phenyl are preferred.

[0018] Hydrogen can be bonded to silicon at the ends of the molecular chain, at the side groups of the molecular chain, or both. In one state, hydrogen is substituted at the end positions. In another state, at least 3 to 4 hydrogen atoms are present per molecule. Hydrogen-containing polyorganosiloxane components can have straight-chain, partially branched straight-chain, branched, cyclic, or network molecular structures, or can be a mixture of two or more different polyorganosiloxanes having the listed molecular structures.

[0019] Hydrogen-containing polyorganosiloxanes include, for example, trimethylsiloxy-terminated methyl hydrogen-containing polysiloxanes; trimethylsiloxy-terminated dimethylsiloxane-methyl hydrogen-containing silica copolymers; trimethylsiloxy-terminated methyl hydrogen-containing silica copolymers; trimethylsiloxy-terminated dimethylsiloxane-methyl hydrogen-containing silica copolymers; dimethylsiloxy-terminated dimethyl polysiloxanes; dimethylsiloxy-terminated methyl hydrogen-containing polysiloxanes; dimethylsiloxy-terminated dimethylsiloxane-methyl hydrogen-containing silica copolymers; dimethylsiloxy-terminated dimethylsiloxane-methyl hydrogen-containing silica copolymers; and dimethylsiloxy-terminated methyl phenyl polysiloxanes.

[0020] The amount of hydrogenated polyorganosiloxane component used is sufficient to cure the composition. A preferred amount is 1.0 to 10 silicon-bonded hydrogen atoms per alkenyl group in the alkenyl-containing polyorganosiloxane component. When the number of silicon-bonded hydrogen atoms per alkenyl group exceeds 10, bubbles may be generated during curing, leading to a gradual decrease in the heat resistance of the cured polysiloxane.

[0021] A convenient method for formulating curable filled compositions is to combine two different two-part curable polysiloxane compositions, each comprising an alkenyl-containing component and a hydrogenated component. Suitable curable polysiloxane compositions may have viscosities, for example, less than 400,000 centistokes (cSt), such as 100,000 to 250,000 cSt. These two-part formulations can be prepared separately or are commercially available.

[0022] Curable polysiloxane compositions may further selectively include reactive polyorganosiloxanes, i.e., polyorganosiloxanes with reactive groups different from alkenyl or reactive Si-H groups, and which can be covalently bonded to the polyorganosiloxanes. Without being bound by theory, it is assumed that reactive polyorganosiloxanes enhance the bonding of the cured polysiloxane layer, particularly the bonding with the backing layer. In this case, the reactive polyorganosiloxane can be represented by the following chemical formula: M′′ aD′′ bT′′ cQ′′ d, The subscripts a, b, c, and d are zero or positive integers, with the restriction that if subscripts a and b are both zero, then subscript c is greater than or equal to two; the chemical formula of M′′ is R 3SiO 1 / 2; the chemical formula of D′′ is R 2SiO 2 / 2; the chemical formula of T′′ is R 2SiO 3 / 2; and the chemical formula of Q′′ is SiO 4 / 2, wherein each R group independently represents hydrogen, alkenyl, substituted and unsubstituted monovalent hydrocarbon group, each having one to forty or one to ten carbon atoms, limited to any alkenyl and / or reactive hydride groups present in polysiloxane, and one or more of the R groups are reactive organic groups. Suitable reactive groups include, for example, acrylic acid, methacrylic acid, and epoxy groups.

[0023] Polyorganosiloxanes containing such reactive groups can be obtained from the reaction of a trialkoxysilane monomer containing reactive groups in the synthesis of polyorganosiloxanes containing reactive groups. Alternatively, the reactive groups can be used as separate components incorporated into the two systems described above (e.g., in the form of trialkoxysilane monomers). Alternatively, diekoxyalkyl silanes and alkoxydialkyl silane monomers containing reactive groups can be used. The alkoxy groups and / or alkyl groups in the aforementioned monomers can have 1 to 10, 1 to 6, or 1 to 3 carbon atoms. A suitable alkoxysilane monomer is an epoxysilane represented by chemical formula (1): R1, R2, and R3 are independently hydrogen or C1-10 hydrocarbon groups; R4 and R5 are independently C1-10 alkylene or C1-10 alkylene groups; and R6, R7, and R8 are independently C1-10 hydrocarbon groups. The hydrocarbon group may contain 1 to 6 carbon atoms, or 1 to 4 carbon atoms. These hydrocarbon groups may be alkyl groups. Preferably, the alkylene or alkylene groups R4 and R5 contain 1 to 6 carbon atoms, or 1 to 4 carbon atoms, or 1 or 2 carbon atoms. The alkylene or alkylene group may be methylene, ethylene, propylene, etc.

[0024] Alkoxysilane monomers can also be (meth)acrylate silanes represented by chemical formula (2): R9, R10, and R11 are individually hydrogen or C1-10 hydrocarbon groups; R12 is a C1-10 alkylene group or a C2-10 alkylene group; and R13, R14, and R15 are individually C1-10 hydrocarbon groups. The hydrocarbon group preferably contains 1 to 6 carbon atoms, or 1 to 4 carbon atoms. These hydrocarbon groups are preferably alkyl groups (e.g., methyl, ethyl, propyl, etc.). The alkylene and alkylene groups preferably contain 1 to 6 carbon atoms, or 1 to 4 carbon atoms. Alkylene groups include methylene, ethylene, propylene, etc.

[0025] In one specific state, the reactive group may be obtained from propylene oxide propyltris(C1-3 alkoxy)silane, propylene oxide propyldi(C1-3 alkoxy)(C1-3 alkyl)silane, 2,3-epoxycyclohexyl-4-ethyltris(C1-3 alkoxy)silane, 2,3-epoxycyclohexyl-4-ethoxyethyldi(C1-3 alkoxy)(C1-3 alkyl)silane, or a combination thereof. The reactive group may be bonded to the ends of the polyorganosiloxane molecular chain, at the side group positions of the molecular chain, or both. In another specific state, the reactive group is provided by combining one or more of the aforementioned monomers with a curable polyorganosiloxane composition.

[0026] Reactive organosiloxanes may contain reactive groups and are calculated per mole of 0.1 to 50 mol% of silicon monomer units, or 0.5 to 45 mol%, or 1 to 40 mol%, or 2 to 40 mol%, based on 100 mol% of silicon monomer units in the organosiloxane of the reactive organosiloxane.

[0027] The content of reactive organosiloxanes in a curable polysiloxane composition can vary considerably depending on the reactive groups and the desired elastomer properties. For example, a curable polysiloxane composition may contain 0.05 to 50 wt%, or 0.1 to 45 wt%, or 0.5 to 40 wt%, or 1 to 40 wt% reactive organosiloxanes based on the total weight of the curable polysiloxane composition.

[0028] Curable polysiloxane compositions may further include polysiloxane fluids to adjust the viscosity of the curable polysiloxane composition, extend the life of the curable filled composition, or provide specific properties to the cured product, such as softness. Suitable polysiloxane fluids have a viscosity of less than 3000 cSt. These polysiloxane fluids reduce the viscosity of the composition, thereby allowing for at least one of the following: increased filler loading, improved filler wetting, improved filler dispersion, and improved coating and casting properties, where desired. Preferably, the polysiloxane fluid does not substantially inhibit the curing reaction, i.e., the addition reaction.

[0029] Polysiloxane fluids can be non-reactive or co-cured with other organosiloxane components. Suitable non-reactive polysiloxane fluids have sufficiently high boiling points to disperse within the polymer matrix, preventing evaporation during or after curing, and avoiding migration to surfaces or venting. They are further selected to exhibit low venting and minimal to no surface migration when using cured polysiloxane layers. Suitable non-reactive polysiloxane fluids have boiling points greater than or equal to 260°C (500°F) and can be branched or linear. Examples of non-reactive polysiloxane fluids include Dow Corning Corporation's DC 200.

[0030] When the polysiloxane fluid is co-curable, it can become part of the polymer matrix through covalent bonding, thereby minimizing venting and / or surface migration. The polysiloxane fluid can be co-cured with an alkenyl-containing polyorganosiloxane and a polyorganosiloxane having at least two silicon-bonded hydrogen atoms, and therefore may itself contain an alkenyl group or a silicon-bonded hydrogen group. These compounds may have the same structure as the aforementioned alkenyl-containing polyorganosiloxane and polyorganosiloxane having at least two silicon-bonded hydrogen atoms, but otherwise, their viscosity is less than 1000 cSt, and preferably they have a boiling point greater than the curing temperature of the addition curing reaction, i.e., greater than or equal to 260°C (500°F).

[0031] The curable polysiloxane composition further comprises a curing catalyst, which is generally a component comprising a portion of a polyorganosiloxane having at least two alkenyl groups per molecule, specifically a hydrosilylation catalyst. An effective catalyst promotes the addition of hydrogens bonded to silicon to multiple alkenyl groups to accelerate curing. Such catalysts may contain noble metals, such as platinum, rhodium, palladium, ruthenium, iridium, or combinations thereof. The catalyst may also contain auxiliary materials, such as activated carbon, alumina, silica, polymer resins, or combinations thereof. An effective amount of catalyst for curing the polysiloxane composition is used, which is generally a metal (e.g., platinum) based on the total content of the reactive organosiloxane component from 0.1 to 1000 parts per million (ppmw).

[0032] Platinum and platinum-containing compounds are preferred, including, for example, platinum black, platinum powder on alumina, platinum powder on silica, platinum powder on carbon, chloroplatinic acid, alcohol solutions of platinum-chloroplatinic acid-olefin complexes, platinum-alkenyl silicate complexes, and catalysts provided by micronization of the catalyst dispersed in a polymer resin, such as methyl methacrylate, polycarbonate, polystyrene, polysiloxane, etc. Combinations of different catalysts can also be used. When using a platinum catalytic system, catalyst poisoning may occur, which may result in low-strength uncured or poorly cured polysiloxane compositions. Additional platinum can be added, but adding large amounts of platinum to improve curing may negatively impact pot life or working time. Methyl vinyl rings can be used as curing inhibitors, such as Dow Corning's 1-2287 Cure Inhibitor. These materials bond platinum at room temperature to prevent curing and thus improve working time, but release platinum at higher temperatures to affect curing within the desired time. The amount of platinum and curing inhibitor can be adjusted to change the curing time and working time / pot life. When excessive platinum is used, it is generally less than or equal to 1 wt% of the total weight of the polyorganosiloxane mixture, fillers, and other additives. Preferably, within this range, the additional platinum concentration (i.e., the amount exceeding the requirement) is greater than or equal to 0.05 wt% or greater than or equal to 0.15 wt% based on the total weight of the polyorganosiloxane mixture. Also within this range, the additional platinum concentration is less than or equal to 0.6 wt% or less than or equal to 0.45 wt%, depending on the type and amount of filler used.

[0033] The concentration of the curing retarder (if a curing retarder is used) is less than or equal to 0.3 wt% of the total composition. Within this range, the curing retarder concentration is greater than or equal to 0.005 wt% or greater than or equal to 0.025% based on the total weight of the polyorganosiloxane mixture. Also within this range, the curing retarder concentration is less than or equal to 0.2 wt% or less than or equal to 0.1 wt% based on the total weight of the curable polysiloxane composition and the required working time or pot life.

[0034] Any portion of the curable polysiloxane composition may contain other additives, such as ultraviolet (UV) stabilizers, antistatic agents, pigments, antibacterial or antiviral agents, or combinations thereof. When additives are present, their amounts are selected so that the desired properties of the cured polysiloxane composition are not negatively affected by the presence of the additives.

[0035] To allow for the addition, incorporation, and impregnation of the expanded polymer microspheres and filler composition, the curable polysiloxane composition (excluding expanded polymer microspheres and fillers) must have a viscosity of less than 100,000 cSt, or less than 85,000 cSt, or less than 75,000 cSt. Alternatively, or otherwise, the curable polysiloxane composition (excluding expanded polymer microspheres and fillers) must have a net extrusion rate of less than 500 g / min according to ASTM C-603-98.

[0036] Finally, the components of the curable polysiloxane composition are selected to provide a cured foam with a low glass transition temperature (Tg), such as less than 0°C, less than -50°C, or less than -115°C. Expanded polymer microspheres

[0037] In addition to the curable polysiloxane composition, the curable filled composition used to manufacture the filled polysiloxane foam layer further comprises a plurality of expanded polymer microspheres. As used herein, "expanded polymer microsphere" refers to a polymer shell encapsulating gas and includes shells that are not perfectly spherical; for example, such shells have a hemispherical shape when cut and observed by scanning electron microscopy (SEM). Because the expanded polymer microspheres encapsulate gas within the polymer shell, they can serve as pre-constructed foam-like gas chambers.

[0038] The encapsulated gas may include, for example, air, nitrogen, argon, carbon dioxide, or combinations thereof. The gas may be an organic gas, such as isobutane, isopentane, or combinations thereof. The polymer shell contains the gas; and the polymer shell can contain the gas under pressure. Examples of polymer shells include thermoplastic polymers, such as polyacrylonitrile / methacrylonitrile shells and poly(ethylene chloride) / polyacrylonitrile shells. The shell may be incorporated with inorganic particles, such as silicates, calcium-containing or magnesium-containing particles, which can facilitate the separation of polymer microspheres.

[0039] It should be understood that the microspheres used in this invention are expanded (i.e., pre-expanded), not expandable. Expandable microspheres are commercially available and are often expanded during processing. However, it has been found that using expandable microspheres that expand in situ during formulation or curing can result in textured surfaces or undesirable surface defects. When examined by a drop ball impact test, formulations containing undesirable textures exhibit lower energy absorption.

[0040] Conversely, expanded polymer microspheres are expanded before incorporation into the curable polysiloxane composition. The use of expanded polymer microspheres provides a mechanism to reduce the impact on the foam layer while maintaining a consistent thickness at the micron level. Expanded polymer microspheres can grow to, for example, 10% to 60%, a final average diameter of 20 to 200 micrometers (µm) before expansion. However, for the fabrication of polysiloxane foam layers with smooth surfaces, optimal overall results are achieved when the maximum diameter of the expanded polymer microspheres is smaller than the thickness of the foam layer. Accordingly, the maximum diameter of the expanded polymer microspheres can be less than 300 µm, or 200 µm or less, or 150 µm or less, or 100 µm or less, or 50 µm or less, depending on the desired foam thickness. The D50 of expanded polymer microspheres conforming to this absolute particle size can be 10 to 200 µm, or 20 to 150 µm, or 10 to 100 µm. In one state, the D50 of the expanded polymer microspheres is 10 to 80 µm, for example, 20 to 60 µm. The expanded polymer microspheres can selectively exhibit a multi-peaked median particle size distribution, provided that the maximum diameter is not exceeded.

[0041] Expanded polymer microspheres can be dry or wet when incorporated with curable filled components, and can be non-suspended or suspended in aqueous solutions, organic solutions, or combinations thereof. Expanded polymer microspheres (wet or dry) can be selectively surface-pretreated, for example with silanes, fluoroalkyl groups, long-chain carboxylic acids having 8 to 30 carbon atoms, silicon dioxide, calcium carbonate, or combinations thereof. Long-chain carboxylic acids can have 10 to 20 carbon atoms and can be branched or unbranched, saturated or unsaturated. One example includes stearic acid. The silane used for pretreatment can be a reactive organic functional silane, such as a silane having alkenyl, hydroxyl, C1-12 alkoxy, halide, mercapto, or combinations thereof. Expanded polymer microspheres, with or without various surface pretreatments, are commercially available from Nouryon under the trade name EXPANCEL.

[0042] Pretreated microspheres, especially dried pretreated microspheres, can serve not only as extrusion zones, but also, without being bound by any theory, as a lubricant rather than a binder for other fillers present in the matrix. Again, without being bound by any theory, it is believed that some of the energy dissipated in the polysiloxane is dissipated as heat through friction between the treated filler and its surface, thus also serving as an extrusion zone.

[0043] The content of expanded polymer microspheres in a curable filled composition can vary depending on the polysiloxane composition, the type of expanded polymer microspheres, the amount and type of filler composition as described below, and the desired properties. The amount of expanded polymer microspheres can be further calculated based on volume fraction, which indicates the amount that produces optimal shock absorption and dissipates the most joules of kinetic energy from the impact. For example, the amount of curable filled composition included is 0.1 to 10 parts by weight (pbw), or 0.5 to 8 pbw, or 1 to 5 pbw, based on the total weight of the curable filled composition. Particulate filler composition

[0044] In addition to expanded polymer microspheres, curable filled compositions used to manufacture thin polysiloxane foams include particulate filler compositions. Similarly, to manufacture polysiloxane foam layers with smooth surfaces, the maximum size of each filler used is 200 µm or less, or 150 µm or less, or 100 µm or less, or 50 µm or less, depending on the desired foam thickness. The diameter (D50) of the particulate filler composition conforming to this absolute particle size (as defined herein, may refer to the equivalent sphere diameter) can be 100 µm or less, or 70 µm or less. Accordingly, the suitable particulate filler composition can have a diameter D50 of 10 to 100 µm, or 20 to 100 µm. In one sample, the diameter D50 of the particulate filler composition can be 10 to 80 µm, for example, D50 of 20 to 60 µm. The median particle size of a particulate packing composition can selectively exhibit a multimodal distribution, provided it does not exceed the maximum diameter. This multimodal distribution can result from using two different particulate packings or a single packing with two or more modes.

[0045] Possible fillers for use in filler compositions are microparticles, which may include inorganic fillers such as ceramics, clay, silicates, or multiple ceramic or glass microspheres; or organic fillers such as polymeric silsesquioxanes or methylphenyl MQ resins; or combinations thereof.

[0046] In one state, the particles can be any regular or irregular shape, such as: disc, fiber, sheet, disk, rod (solid or hollow), sphere (solid or hollow), or whisker. In another state, the shape and modulus of the particles can make them easier to extrude and provide improved extrusion properties. Such shapes include, for example: disc and hollow rod.

[0047] A suitable organic filler is particulate paraffin. As is known in the art, paraffin comprises a mixture of solid straight-chain hydrocarbons with melting points ranging from 48° to 66°C (120° to 150°F). Paraffin can be obtained from petroleum by dewaxing light lubricating oil feedstocks.

[0048] Suitable inorganic fillers include alumina, aluminum trihydrate, aluminum nitride, aluminum silicate, barium titanate, beryllium oxide, boron nitride, calcium carbonate, corundum, magnesium oxide, magnesium hydroxide, glass, mica, nano clay, quartz, silicon carbide, strontium titanate, talc, titanium dioxide (such as rutile and anatase), wollastonite, etc.

[0049] In one-phase samples, the filler composition contains silicon dioxide, such as fumed silicon dioxide. Calcium carbonate can be used.

[0050] In one state, the filler composition includes clay with a plate-like, layered morphology, such as kaolin. Kaolin is an aluminosilicate hydrate, which is available from a variety of commercial sources. Using a hexagonal plate-like structure allows for the introduction of a unique geometry into the system, increasing the potential presence of compression zones.

[0051] In another configuration, clay with a hollow tubular shape can be used, specifically as the compression zone. The combination of clay and hollow tube geometry makes the filler an excellent energy absorber because the hollow tube has a low modulus and is relatively easy to break under certain impact test conditions. The clay can be hydrous kaolin, an aluminosilicate clay exhibiting a hollow tubular nanostructure. Hydrous kaolin tubes range in length from 0.5 to less than 3.0 µm, with an outer diameter ranging from 50 to 70 nanometers and an inner diameter (cavity) ranging from 15 to 30 nanometers. Hydrous kaolin is chemically identical to kaolin clay (Al₂Si₂O₅(OH)₄xnH₂O), with a layer of water molecules between the alumina and silica layers. Hydrous kaolin is commercially available from Applied Materials, Inc. under the brand name DRAGONITE™.

[0052] In another embodiment, the filler composition comprises glass or ceramic microspheres, particularly hollow glass microspheres, i.e., hollow spherical glass particles obtained from glass such as alkaline borosilicate glass (e.g., sodium borosilicate glass). Hollow glass microspheres can possess low specific gravity, good heat resistance, thermal insulation properties, compressive strength (e.g., crushing strength), and impact resistance. Each hollow glass microsphere can have a substantially spherical morphology and substantially spherical internal voids. The average diameter of the hollow glass microspheres can be from 10 to 200 µm.

[0053] In another embodiment, polyhedral oligomeric silsesquioxanes (commonly referred to as "POSS") may be included in the filler composition. POSS is a nanoscale inorganic material having a silicon dioxide core with inert or reactive functional groups on its surface. The silsesquioxane may have a cubic or near-cubic structure comprising silicon atoms at the ends and interconnected oxygen atoms. Each silicon atom may be covalently bonded to an R group at one of the alkyl positions. The silsesquioxane may be substituted or unsubstituted, such that each R group may be independently hydrogen, hydroxyl, alkyl, aryl, or alkenyl, wherein the R group may have one to twelve carbon atoms and one or more heteroatoms (e.g., at least one of oxygen, nitrogen, phosphorus, silicon, or halogen). Each R group may independently contain one or more reactive groups, such as at least one of alcohols, epoxy groups, esters, amines, ketones, ethers, halides, or combinations thereof. Each R group may independently contain at least one of silanols, alkoxides, or chlorides. In one state, one or all of the R groups are hydrogen, methyl, or a combination thereof. One example of a silsesquioxane is octa(dimethylsiloxy)silsesquioxane.

[0054] One or more of the aforementioned fillers may be dry or wet and may be selectively surface-pretreated, for example, through silanes, fluoroalkyls, long-chain carboxylic acids having 10 to 30 carbon atoms such as stearic acid, silica, calcium carbonate, or combinations thereof. Expanded polymer microspheres, particularly dry, pretreated microspheres, can serve not only as an extension zone but also, without being bound by any theory, are believed to act as a lubricant rather than a binder for other fillers present in the matrix. Again, without being bound by any theory, it is believed that some of the energy dissipated in the polysiloxane is dissipated as heat due to the friction between the pretreated filler and the surface, simultaneously serving as an extension zone. In another advantageous feature, the use of surface pretreatment improves the dispersion of the filler in the curable filled composition and allows for higher loading of the expanded microspheres and fillers. In particular, when the dispersion is not completely uniform, surface pretreatment can serve as a safeguard against energy dissipation in formulations containing a filled polysiloxane foam layer with a volume fraction of more than 3%.

[0055] Finally, the filler composition may include particulate methylphenyl polysiloxane resin, namely methylphenyl MQ resin, where M′′ is R3SiO and Q is a SiO4 unit, and R is a combination of methyl and phenyl. The presence of methylphenyl MQ resin was unexpectedly found to provide improved energy absorption from shocks. The concentration of phenyl groups present in the MQ resin was therefore optimized to enhance energy absorption from shocks.

[0056] Methylphenyl MQ resin is solid at room temperature and can be in powder or flake form. For ease of handling, methylphenyl MQ resin can be provided in combination with the aforementioned alkenyl-terminated organosiloxanes. Although methylphenyl MQ resin is provided as particulate solids in curable filled compositions, the alkenyl-terminated organosiloxane-containing component, curable polyorganosiloxane composition, or curable filled composition can be processed to at least partially or completely dissolve the particulates. For example, the alkenyl-terminated organosiloxane-containing component can be formed by shearing and mixing various materials (including methylphenyl MQ resin) at 80°C for 4 hours, melting resin flakes in a container and mixing them into the polymer, or using a solvent such as benzene or toluene to improve solubility and then removing the solvent after mixing. Manufacturing method

[0057] Curable filled compositions can be manufactured by combining various components in any suitable order. In one state, the composition comprising an alkenyl-substituted polyorganosiloxane, a catalyst, a filler, and any additives is mixed as a first part, and then combined with a hydrogenated polyorganosiloxane as a second part.

[0058] The pot life of curable, filled compositions can range from minutes to more than a week, depending on the composition used and the curing method. As used herein, the term "pot life" refers to the time elapsed from the start of the curing process (e.g., by combining co-curable components in the presence of a catalyst) until the ideal properties of flowability and / or processability are no longer conducive to the manufacturing process in order to provide a suitable product. Properties affected by the pot life of polysiloxane compositions include, for example, extrudability, flowability, coating quality, coating uniformity, coating thickness, and the number of defects. Pot life is typically assessed at room temperature and, in one state, measured from the initial contact of the co-curable component of the polysiloxane composition with any suitable catalyst, can be greater than or equal to 4 hours, or greater than or equal to 6 hours, or greater than or equal to 8 hours, or greater than or equal to 10 hours, or greater than or equal to 12 hours. In a particular state, the pot life of a polysiloxane composition ranges from 12 hours to 9 days.

[0059] A filled polysiloxane foam layer can be formed by casting a curable filled composition and then curing the cast composition. A convenient method for preparing a filled polysiloxane foam layer from a curable filled composition involves mixing different components into a homogeneous mixture and removing air by degassing in a vacuum.

[0060] Curing times for curable filled compositions are ideally shorter at higher temperatures. Therefore, curing times of 1 to 25 minutes, 5 to 20 minutes, 7 to 15 minutes, or 10 to 12 minutes are useful at higher temperatures. These curing times are ideal when using rapid, efficient mixing, heating, and / or curing, and automated dispensing of compositions.

[0061] Suitable curable filled compositions, compared to shorter-term, faster-curing polysiloxane compositions, may contain a lower proportion of curing agent, a higher proportion of catalyst inhibitor, a higher weight content of reactive crosslinking groups (e.g., alkenyl and active silyl groups), or combinations thereof, sufficient to increase the curing time at room temperature from 1 to 20 minutes to greater than or equal to 7 days. When the curing time at room temperature is increased to this extent, temperature or other methods of achieving curing allow for a controlled, shorter working life, suitable for processes requiring pre-curing manipulation of polysiloxane compositions, where curing is achieved under a set of controlled conditions. Curing can be achieved using heat, ultraviolet radiation, visible light radiation, pressure, or combinations thereof. In one state, the curable filled composition is cured at temperatures greater than or equal to 80°C, or greater than or equal to 90°C, or greater than or equal to 100°C, or greater than or equal to 125°C, or greater than or equal to 150°C. Suitable curable filled compositions may allow a working life of less than 30 minutes, or less than 25 minutes, or less than 20 minutes, or less than or equal to 15 minutes at 100°C. In another embodiment, suitable curable filled compositions may allow a working life of less than 12 minutes, or less than 10 minutes, or less than 9 minutes, or less than 8 minutes at 125°C. In yet another embodiment, suitable curable filled compositions may allow a working life of less than 10 minutes, or less than 8 minutes, or less than 6 minutes, or less than 5 minutes at 150°C.

[0062] Alternatively, a phased curing process can be used, such as a first curing at a lower temperature (e.g., 60 to 80°C) for a first period of time (e.g., 5 to 15 minutes), followed by a second curing at a higher temperature (e.g., 90 to 130°C) for a second period of time (e.g., 5 to 20 minutes). Post-curing can be used in conjunction with any of the aforementioned curing methods, such as at 80 to 150°C or 100 to 140°C for a period of time (e.g., 30 minutes to 3 hours). Post-curing is particularly helpful in strengthening the adhesion of the polysiloxane foam layer to any suitable backing layer.

[0063] The curable filled composition can be cast onto a backing layer, adhesive composition, or release liner, and can be cured by maintaining the composition at room temperature (e.g., 25°C) or by heating as described above. When a non-reactive organosiloxane fluid is present, the curing temperature is below the boiling point of the fluid to substantially prevent fluid removal during curing. Preferably, the curing temperature is at least 20°C, or at least 50°C, or at least 80°C below the boiling point of the fluid component. When a reactive fluid is used, the curing temperature is the temperature at which the fluid cures before being expelled. Selective post-curing operations can be used. When the cured polysiloxane layer is formed on the carrier, it can be adhesive-coated or transferred to the backing layer. Transfer methods can include lamination, rolling, or calendering.

[0064] In a continuous process, a curable filled composition is transferred onto a moving carrier. Another carrier film is selectively pulled over the mixture, and the clamped mixture is then pulled through a coating machine, which determines the final thickness of the elastomer. The composition is then cured and selectively post-cured. In a single-phase process, continuous manufacturing in roll form is used for ease of subsequent manufacturing and lower costs. This allows for the fabrication of filled polysiloxane layers from liquid compositions in continuous rolls of cast sheets of varying thicknesses, resulting in better thickness tolerances.

[0065] A smooth (textured release) layer is preferred. The adhesive can be selectively applied to the side of the release layer opposite the curable filled composition. Alternatively, the curable filled composition is cast onto the release layer, and the backing layer is applied to the opposite side before curing. In another embodiment, the backing layer applied to the opposite side before curing comprises adhesive and a release liner. Using two backing layers is advantageous when one layer can inhibit the curing of the polysiloxane composition. For example, complete curing of the polysiloxane composition can be inhibited if the curable filled composition is directly applied to the polyurethane backing layer during or before curing. Increasing the amount of curing catalyst, reducing the inhibitor load where possible, applying a protective layer to the polyurethane surface, or increasing the number of reaction sites in the polysiloxane composition can overcome any reduced reactivity at the interface between the polysiloxane composition and the polyurethane during curing. Alternatively, where appropriate, the use of a backing layer between the curable filled composition and the polyurethane can overcome any curing-related difficulties, specifically when the backing layer does not have reactive functional groups that could interfere with the curing of the polysiloxane composition.

[0066] After curing, in a one-state sample, the filled polysiloxane foam layer absorbs liquid to further improve impact performance, such as water, a non-reactive solvent, or a low molecular weight polysiloxane oil. In a one-state sample, a low molecular weight, non-reactive polysiloxane oil is absorbed to further improve impact performance. Polysiloxane oils can absorb a large amount of energy from an impact without transferring energy to adjacent sides or the polysiloxane material. Suitable oils are non-reactive and may have a viscosity below 1000 cSt, or below 750 cSt, or below 600 cSt, or below 500 cSt. Exemplary polysiloxane oils include dimethyl polysiloxane oil, methylphenyl polysiloxane oil, diphenyl polysiloxane oil, and methyl hydrogen-containing polysiloxane oil. Particularly useful polysiloxane oils are generally homopolymers, especially dimethyl polysiloxane oil. Other useful polysiloxane oils include those modified with alkyl or fluoroalkyl groups, polyether-modified polysiloxane oils, methylstyrene-modified polysiloxane oils, alkyl-modified polysiloxane oils, fatty acid-modified polysiloxane oils, alkoxy-modified polysiloxane oils, and fluorine-modified polysiloxane oils; and linear polysiloxane oils, such as fluorine-modified polysiloxane oils. Polysiloxane oils can be impregnated, coated, soaked, or otherwise aspirated using techniques that do not cause the filled polysiloxane layer to expand significantly beyond the desired thickness. For example, a foamed layer can be placed in polysiloxane oil under vacuum for a suitable period of time. Properties of filled polysiloxane foam layers

[0067] Cured filled polysiloxane (PVC) obtained from a curable filled composition is a flexible and compressible foam. As used herein, "foam" refers to a material having a porous structure. The density of cured PVC foam can be, for example, less than 55 pounds per cubic foot (pcf) (881 kg / m³) or less than 25 pcf (200 kg / m³), based on a total volumetric porosity of at least 5% to 99%, preferably greater than or equal to 30%, or a combination thereof. The density of the foam can be measured from a thicker sample of the foam, such as a sheet one inch (2.54 cm) thick.

[0068] The filled polysiloxane foam layer is advantageously extremely thin, yet still retains excellent impact properties. The thickness of the filled polysiloxane foam layer can be 20 to 300 µm, or 40 or 200 µm, or 50 to 250 µm, preferably 60 to 200 µm.

[0069] Filled polysiloxane (PVC) foams retain their elasticity after multiple cycles of compressive flexural stress throughout their lifespan, properties reflected in compressive flexural stress and compression set. Foams with good compression set resistance provide cushioning and maintain their original shape or thickness under prolonged loads. In one sample, the compressive flexural stress of filled PVC foam is 0 to 25 psi (0 to 172 kPa) per square inch, preferably 0 to 15 psi (0 to 103 kPa), determined according to ASTM D3574-17 at 25% flexural stress. The compression set of filled PVC foam can be 0 to 5%, determined according to ASTM D3574-95 Test D at 70°C.

[0070] To determine the suitability of the filled polysiloxane foam for impact absorption, a drop ball test as described in the examples can be performed. A 4.5 g stainless steel ball and an impact distance of 0.1 m can be used. Other steel ball masses, such as a 28.5 g steel ball at 0.3 m and impact distances, can be used to demonstrate the usefulness of the foam under other, more demanding conditions.

[0071] Filled polysiloxane foam can have low water absorption rates, such as less than 5 wt%, less than 3 wt%, or less than 2 wt%. This is determined by heating the sample at 50°C for 24 hours, then immersing the sample in water at room temperature for 30 seconds, and measuring the weight of the absorbed water. In a single-state sample, the water absorption rate can be determined by cutting a 100 mm x 100 mm sample, storing it at 50°C for at least 24 hours, and then measuring the weight W1 of the sample. The sample is submerged in water at room temperature for 30 seconds and then removed from the water. The water is removed from the sample surface, and its weight is recorded as W2. The percentage water absorption rate is calculated using the equation ((W2-W1) / W1)*100.

[0072] The filled polysiloxane foam may have the following combination: compressive flexural strength of 0 to 25 pounds per square inch (0 to 172 kPa) at 25% flexural strength as determined by ASTM D3574-17, preferably 0 to 15 pounds per square inch (0 to 103 kPa), and compressive settling of 0 to 5% as determined by ASTM D 3574-95 Test D at 70°C.

[0073] In one state, the filled polysiloxane foam may have a combination of the aforementioned properties, such as: a low glass transition temperature, for example below -115°C; low compression set, for example 0 to 5% at 70°C as determined by ASTM D 3574-95 test D, and 0 to 15 psi (0 to 103 kPa) of compressive force flexural strength as determined by ASTM D3574-1 at 25% flexural strength; and low water absorption, for example, less than 2 wt% as determined as above.

[0074] In a preferred embodiment, the thickness of the filled polysiloxane foam layer is 60 to 200 µm, and it is formed from the following: high molecular weight vinyl-terminated polydimethylsiloxane (PDMS), 3 to 7 wt%, preferably 4 to 6 wt%, of lower molecular weight vinyl-terminated poly(methylphenyl)siloxane, 0.5 to 2 wt%, or 0.8 to 1.2 wt%, of dried, selectively treated, pre-expanded polymer microspheres, and 1 to 3 wt%, preferably 1.8 to 2.2 wt%, of kaolin clay, preferably kaolin with a hollow tubular nanostructure, based on the total weight of the filled polysiloxane foam layer.

[0075] In another preferred embodiment, the thickness of the filled polysiloxane foam layer is 60 to 200 µm, and it is formed of: high molecular weight vinyl-terminated PDMS, 3 to 7 wt%, preferably 4 to 6 wt%, of low molecular weight vinyl-terminated poly(methylphenyl)siloxane, 0.5 to 2 wt%, or 0.8 to 1.2 wt%, of dried, silica-treated pre-expanded polymer microspheres, 2 to 8 wt%, preferably 3 to 7 wt%, of stearic acid-treated calcium carbonate, and 2 to 8 wt%, preferably 3 to 7 wt%, of vinyl-terminated silane-treated hexagonal flake kaolin, each based on the total weight of the filled polysiloxane foam layer.

[0076] Polysilicon foam layers are particularly useful for electronic devices with screens, such as portable or handheld electronic devices. Particularly useful applications are for handheld devices with liquid crystal displays (LCDs) or OLED screens. The screen can be flexible, i.e., bendable, rollable, foldable, etc. Various layers in such devices are known and can completely or partially cover each other. It is also understood that the various layers can be in direct physical contact with adjacent layers (directly disposed on top) or disposed on top of each other, allowing for the presence of any suitable intermediate layer, such as an adhesive layer.

[0077] Unwilling to be bound by any theory, the inventors of this case are believed to have developed a formulation that provides the importance of the "extrusion zone," the geometry of the extrusion zone, thermal efficiency across a wide temperature range, optimal loading for the interaction of the smallest particles, and the mode of dissipating the maximum amount of energy at the micron level through mutual friction between coated fillers in a highly filled medium. In contrast, prior art addresses the thermal properties of a given material, specifically its glass transition temperature and inherent elastomeric properties that mitigate impact upon initial contact, as well as impact-mitigating properties such as hardness, density, and filler content.

[0078] In summary, the filled polysiloxane foam layer is a single-layer polysiloxane foam material comprising expanded polymer microspheres and a specific filler packaging combination, providing micron-scale "extrusion zones" that significantly reduce, dissipate, or absorb impact energy. The polymer microspheres and filler packaging are dispersed in a polydimethylsiloxane matrix and cured using a hydrosilicification reaction to form a solid but porous polysiloxane sheet. The concentration of phenyl groups present in the curable filled composition is thus optimized to enhance energy absorption from impacts. The microspheres and fillers contained in the polysiloxane foam exist at specific concentrations and combinations to promote optimal interaction with the polysiloxane chains, thus allowing the extrusion zones to absorb as much impact as possible. Using polysiloxane as a medium or network polymer offers many advantages that meet current market demands, such as softness and the ability to perform consistently under various thermal conditions. It also achieves higher filler loading, which is not possible in prior art, such as polyurethane foam, (meth)acrylate, or mixed (meth)acrylate polymer systems. Compared with filled polysiloxane foam, these prior art compositions further exhibit poor compression set, higher water absorption and higher Tg, making them more sensitive to thermal changes, especially at low temperatures.

[0079] The following examples are for illustrative purposes only and are not intended to limit the composition, layer or article made from the materials, conditions or process parameters presented in the examples. Example Material

[0080] The following materials are used in the examples. [name] [Product Name] [] [(source)] [] [describe] Vi-100000 FLD 621V100000, Vinyl-terminated PDMS, 100,000 cSt Vi-6000 FLD 621V60000 Vinyl-terminated PDMS, 60,000 cSt Vi-350 FLD 621V350 Vinyl-terminated PDMS, 350 cSt Vi-600 FLD 621V600 Vinyl-terminated PDMS, 600 cSt Vi-15DPS / DMS-10000 / PDV-1641 Vinyl-terminated poly(15-17% diphenylsiloxane-dimethylsiloxane), 10,000 cSt Vi-3DPDMS-60000 PDV-0346 Vinyl-terminated poly(3.0-3.5% diphenylsiloxane-dimethylsiloxane), 60,000 cSt Vi-15DP / DMS-5000 PDV-1635 Vinyl-terminated poly(15-17% diphenylsiloxane-dimethylsiloxane), 5,000 cSt Vi-DPS / MPS / DMS SiSiB® VF 6800-2500 Vinyl-terminated poly(dimethylsiloxane-methylphenylsiloxane-diphenylsiloxane), 2,500 cSt Vi-DPS / MPS / DMS mixture A mixture of SiB® VF 6800-2500 and PDV-0346 A mixture of vinyl-terminated poly(dimethylsiloxane-methylphenylsiloxane-diphenylsiloxane), 2,500 cSt and vinyl-terminated poly(3.0-3.5% diphenylsiloxane-dimethylsiloxane), 60,000 cSt. Vi-polymer, low FLD 50620W Vinyl-terminated dimethylsiloxane copolymer, low viscosity, 400 cSt curing agent Trimethylsilyl-terminated methyl hydrogen siloxane-dimethylsiloxane copolymer CAS No. 68037-59-2 Pt-cat PT 56710C Platinum-containing catalyst complexes and inhibitors ExD Expancel 551 DE 30 d42 (Nouryon) Dry, expanded polymer microspheres (particle size 25-50 micrometers (μm), density 42+ / - 2 kg / m³) ExDT Expancel 461 DET 40 d25 (Nouryon) Dry, expanded, and SiO2-treated microspheres (particle size 35-55 μm, density 25+ / - 3 kg / m3) ExW Expancel W (Nouryon) Moistened, swollen polymer microspheres (for easy dispersion in water) GMS 3M K15 glass spheres Borosilicate glass microspheres, 60 nanometer (nm) size St-CaCO 3 Winnofil SPM Calcium carbonate treated with stearic acid VSi-Kaolin Polarite 503-S Calcined kaolin (hexagonal flaky hydrous aluminosilicate clay) treated with vinylsilane SiO 2-1 TPX-5030 Vaporized silica (colloidal silica, 115 nm particle size) treated with HDMZ SiO 2-2 TS-530 Vaporized silicon dioxide (8 nm particle size) treated with HDMZ SiO 2-3 Aerosil Hydrophilic fumed silica Water-rich kaolin Dragonite HP High-density polyethylene (HDPE) contains water-rich kaolin (aluminate silicate clay). POSS Methyl-substituted polyhedral oligomeric silica silsesquioxanes (POSS) MQ XJY-8205A Polysiloxane MQ (CAS No. 68988-56-7), powder XYJ 8010A Flake-shaped methylphenyl polysiloxane, containing 25:75 methylphenyl polysiloxane: vinyl-terminated PDMS (V100k) Inhibitors DC1-2287 Methyl vinyl-cyclic-D4 siloxane (MV-CYC-4) method

[0081] The polysiloxane layer is prepared by combining the formulations shown below and then forming a layer. The amounts of each component are expressed in parts by weight, and the total weight of the listed components is also shown. Each formulation further contains 0.00163 parts by weight of an inhibitor (DCI-2287), which is in addition to the total weight shown. All percentage values ​​are by weight.

[0082] Unless otherwise stated, the components of each embodiment are manually mixed to form a first portion comprising an alkenyl polyorganosiloxane, a catalyst, additives, and fillers, and a second portion comprising a hydrogenated polyorganosiloxane as a curing agent. The first and second portions are combined in a weight ratio of 25:1 to 100:1. The formulation is then applied to a roller-roller coater between two release liner layers and cured at, for example, 70°C to 130°C for 10 to 25 minutes to form a layer of the desired final thickness (without chemical foaming).

[0083] The cured layer was tested using a drop ball apparatus, where, following accepted practice, the cured polysiloxane foam layer was placed above a load sensor connected to high-frequency data acquisition (DAQ) and force measurement software. The load sensor was placed in the drop ball test apparatus, where a 4.5 g stainless steel ball was placed 0.1 m above the sample and dropped. The software then recorded and reported the force readings, which were then compared to a control drop ball test with a sample without foam / elastomer material. Other steel ball masses and impact distances were also tested, such as a 28.5 g steel ball at 0.3 m. In the table below, "Pass" indicates a pass result in the drop ball apparatus, and "Fail" indicates a failure result. If no pass or failure is given, the sample was not evaluated in this test. Formula and Results

[0084] Table 1 shows the formulations containing vinyl silicone polymer and an increased amount of wettable, expandable polymer microspheres. Table 1 [] 1 2 3 4 [Element] 2.5% ExW* 3% ExW* 4% ExW* 0% ExW* Vi-60000 0.7311 0.7270 0.7199 0.7499 Vi-100000 0.2437 0.2430 0.2400 0.2500 Pt-cat 0.000163 0.000163 0.000163 0.000163 ExW 0.025 0.03 0.04 -0 Total value 1.000 1.000 1.000 1.000 Pass / Fail fail fail fail fail *Comparison

[0085] As can be seen from Table 1, all samples failed without filler components.

[0086] Table 2 shows formulations containing curable polyorganosiloxane compositions, comprising one of three different types of phenylsiloxanes, and equal amounts of moistened, expanded polymer microspheres. These formulations may further include particulate fillers with or without low-viscosity copolymers. Table 2 5 6 7 8 9 10 11 Element 3% + 5% Phenylenol* 3% + 20% Phenylenol* 3% + 20% phenyl + 10% CaCO3 3% + 20% phenyl + 10% silicon dioxide 3% + 20% phenyl + 10% mixed filler 3% + 20% phenyl + 10% CaCO3^ 3% + 20% phenyl + 10% CaCO3^ + Low viscosity copolymer Vinyl polysiloxane 0.6899 0.577 0.5024 0.5024 0.5024 0.5061 0.5061 Vinyl polysiloxane 0.2300 0.192 0.1675 0.1675 0.1675 0.1687 0.1487 Vinyl polysiloxane - - - - - 0.04 0.04 Pt-cat 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 Vi-15DP / DMS-10000 / 0.05 0.2 0.2 0.2 0.2 - - Vi-DP / MP / DMS - - - - - 0.105 - Vi-DP / MP / DMS mixture - - - - - - 0.105 Vi-polymer, low - - - - - - 0.02 ExW 0.03 0.03 0.03 0.03 0.03 0.03 0.03 St-CaCO3 - - 0.1 0.05 0.15 0.15 SiO2-1 - - - 0.1 0.05 - - Total pbw 1.000 1.000 1.000 1.000 1.0000 1.0000 1.0000 pass / fail pass pass *Comparison ^To be carried out on a larger scale (greater than 100 feet)

[0087] As can be seen from Table 2, using a large quantity of moistened expanded polymer microspheres can provide passing results in the drop ball test. However, to obtain the ideal combination of properties, the combination of expanded polymer microspheres and fillers is tested. Calcium carbonate filler with vinylsiloxane having phenyl backbone groups also provides passing results in the drop ball test.

[0088] Table 3 shows formulations containing a curable polyorganosiloxane composition with low viscosity containing vinyl organosiloxane (Vi-350) and the same amount of wetted, expanded polymer microspheres, with or without calcium carbonate microparticle filler. Table 3 [] 12 13 [Element] Vi-350 Vi-350 Unfilled* Vi-100000 0.5024 0.6132 Vi-350 0.1675 0.3066 Pt-cat 0.000163 0.000163 ExW 0.03 0.03 Vi-DPS / MPS / DMS 0.2 Vi-15DPS / DMS-10000 / 0.05 St-CaCO3 0.1 Total pbw 1.0000 1.000 Pass / Fail fail fail *Comparison

[0089] As can be seen from Table 3, both samples failed in the ball-dropping device test.

[0090] Table 4 shows formulations containing curable polyorganosiloxane compositions, selectively containing phenyl-substituted polysiloxanes having dried, treated, or moistened expanded polymer microspheres, and selective filler compositions (one or more of calcium carbonate, kaolin, fumed silica, or POSS). Some formulations further contain low-viscosity copolymers. Table 4 14* 15* 16 17 18 19 20 twenty one Element ExDT ExDT #2 ExW #2 ExDT+ CaCO3 ExDT + POSS + Silicon Dioxide ExDT + CaCO3 + Kaolin ExDT + POSS + CaCO3 ExDT + Aerosil Vi-60000 0.6988 0.7011 0.7011 0.6674 0.6699 0.6223 0.6374 0.6598 Vi-100000 0.2470 0.2337 0.2337 0.2225 0.2199 0.2075 0.2124 0.2200 Pt-cat 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 ExDT 0.004 0.015 0.01 0.02 0.01 0.01 0.01 ExW - - 0.015 - - - - - Vi-3DPDMS-60000 0.05 - - - - - - - Vi-15DP / DMS-5000 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Vi-polymer, low - - - - 0.01 0.01 0.01 0.01 St-CaCO3 - - - 0.05 - 0.05 0.05 - SiO2-2 - - - - 0.02 - - - SiO2-3 - - - - - - - 0.05 Kaolin - - - - - 0.05 - - POSS - - - - 0.01 - 0.03 - Total pbw 1.0000 1.0000 1.0000 1.0001 1.0000 1.0000 1.0000 1.0000 Pass / Fail pass pass pass pass pass pass *Comparison

[0091] Table 5 shows that formulations containing curable polyorganosiloxane compositions with phenyl polysiloxanes and expandable polymer microspheres, selective low-viscosity copolymers, and selective filler compositions (calcium carbonate, kaolin, or fumed silica) pass the drop ball test. Table 5 [] 2 twenty three* twenty four 25 [Element] DET + MQ + CaCO3 DET + MQ (No filler) ExDT + MQ + Silicon Dioxide ExDT + MQ + Kaolin Vi-60000 0.4900 0.4900 0.6074 0.6074 Vi-100000 0.2000 0.2500 0.2025 0.2025 Pt-cat 0.000163 0.000163 0.000163 0.000163 Vi-15DP / DMS-5000 0.05 0.05 0.05 0.05 Vi-polymer, low - - 0.01 0.01 ExDT 0.01 0.005 0.01 0.01 St-CaCO3 0.05 - - - SiO2-2 - - 0.02 - Kaolin - - - 0.02 Phenylmethyl MQ 0.2 0.2 0.1 0.1 Total pbw 1.0002 0.9952 1.0001 1.0001 Pass / Fail pass pass *Comparison

[0092] As can be seen from Table 5, the two samples containing fumed silica and kaolin passed the test.

[0093] Table 6 shows formulations containing curable polyorganosiloxane compositions with dried, untreated expanded polymer microspheres, and free of kaolin, kaolin, or solid phenylmethyl MQ polymers. Table 6 26* 27 28 [Element] ExD ExD + Kaolin ExD + Methyl MQ Vi-60000 0.7011 0.6636 0.5511 Vi-100000 0.2337 0.2212 0.1837 Pt-cat 0.000163 0.000163 0.000163 ExD 0.015 0.015 0.015 Kaolin - 0.05 - Phenylmethyl MQ - - 0.2 Total pbw 1.0000 1.0000 1.0000 Pass / Fail pass pass pass *Comparison

[0094] As can be seen from Table 6, all samples passed the ball drop test.

[0095] Table 7 shows formulations containing curable polyorganosiloxane compositions comprising phenyl-containing polysiloxanes having dried, treated, or moistened expanded polymer microspheres. The compositions may further selectively include glass microspheres, calcium carbonate, kaolin, fumed silica, POSS, or combinations thereof. Some formulations further contain low-viscosity copolymers.

[0096] The samples marked with "†" in Table 7 are "filled", meaning they contain a large amount of expanded polymer microspheres, fillers, or both (up to about 2% of the total volume of the composition). Table 7 29†, * 30 31† 32 33 34 35 36† 37† 38† 39 40 Element ExDT† (No filler) ExDT + High Ph + CaCO3 + Silicon dioxide ExDT + CaCO3 + Silicon dioxide + POSS 31 ExDT + GMS ExDT + GMS + Fumed Silicon Dioxide GMS (only) ExDT + GMS ExDT + GMS + CaCO3 + SiO2 + POSS (No Vi-60000) ExW + GMS + CaCO3 + SiO2 + POSS (No Vi-60000) ExDT + Silica + POSS (No Vi-100000) ExW + GMS ExW + GMS + Kaolin Vi-60000 0.2287 0.5999 0.5324 0.6449 0.6299 0.6636 0.6599 - - 0.7848 0.6674 0.6298 Vi-100000 0.6861 0.1999 0.1774 0.2149 0.2149 0.2212 0.2199 0.7548 0.7348 - 0.2225 0.2100 Pt-cat 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 0.000163 ExDT 0.02 0.01 0.01 0.015 0.015 - 0.01 0.01 0.01 - - ExW - - - - - - - - 0.03 0.03 0.03 Vi-DPS / MPS / DMS 0.05 0.12 0.1 0.11 0.1 0.1 0.1 0.1 0.1 0.1 0.05 0.05 Vi-polymer, low 0.01 0.01 0.01 - - - - - 0.01 - 0.01 0.01 GMS - - - 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.02 0.02 CaCO3 - 0.03 0.05 - - - - 0.05 0.04 - - - Takane soil - - - - - - - - - - - 0.05 SiO2-1 - 0.03 0.02 - - - - - - - - - SiO2-3 - - 0.1 - 0.3 - - 0.05 0.05 0.07 - - POSS - - 0.02 - - - - 0.02 0.02 0.02 - - Total pbw 0.9950 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0001 1.0000 Pass / Fail fail fail † Filled *Compare

[0097] As can be seen from Table 7, Example 29 shows that a significant amount of filler can be present in the curable filled composition.

[0098] Table 8 shows formulations comprising curable polyorganosiloxane compositions containing phenyl-containing polysiloxanes having dried, treated, or moistened expanded polymer microspheres. The compositions may further selectively include glass microspheres, clay, or combinations thereof. The formulations may further include low-viscosity copolymers. Table 8 ExDT + clay ExDT + GMS + clay ExW + GMS + clay ExW + Water-rich kaolin Water-rich kaolin (only)* Vi-60000 0.6824 0.6786 0.6561 0.6299 0.6449 Vi-100000 0.2274 0.2262 0.2187 0.2099 0.2149 Pt-cat 0.000163 0.000163 0.000163 0.000163 0.000163 Vi-DPS / MPS / DMS 0.05 0.05 0.05 0.1 0.1 Vi-polymer, low 0.01 0.01 0.01 0.01 0.01 ExDT 0.01 - - - - ExW - - 0.03 0.03 - GMS - 0.02 0.02 - - Water-rich ridge clay 0.02 0.015 0.015 0.02 0.03 Total pbw 1.0000 1.0000 1.0000 1.0000 1.0000 Pass / Fail pass pass pass pass *Comparison

[0099] As can be seen from Table 8, the combination of expandable microspheres and water-rich kaolin clay with or without glass microspheres passed the drop ball test.

[0100] Table 9 shows formulations containing curable polyorganosiloxane compositions, comprising phenyl-containing vinyl polysiloxanes and mixtures of phenylmethyl polysiloxane sheets and vinyl polysiloxane (Vi-100000). The formulations further include dried, treated expanded polymer microspheres, glass microspheres, and clay. Low-viscosity copolymers are also present. Table 9 ExD + Phenyl flake resin + Water-rich kaolin ExD + Phenyl flake resin + Water-rich kaolin [Element] [quantity] [Element] Vi-60000 0.3500 0.4500 Phenylenoid tablets: Vi-100000 (25:75) 0.5000 0.4000 Pt-cat 0.000163 0.000163 Vi-DPS / MPS / DMS 0.1 0.1 Vi-polymer, low 0.01 0.01 ExD 0.015 0.015 Water-rich kaolin clay 0.02 0.02 Total pbw 0.9952 0.9952 Pass / Fail pass pass

[0101] As can be seen from Table 9, both samples passed the ball drop test.

[0102] The following are non-limiting embodiments of the present invention.

[0103] State 1. A curable, filled composition for manufacturing a filled polysiloxane foam layer with a thickness of 20 to 300 micrometers, the composition comprising a curable polyorganosiloxane composition including alkenyl-substituted polyorganosiloxane, hydride-substituted polyorganosiloxane, and a curing catalyst; a plurality of expanded polymer microspheres having a maximum size smaller than the thickness of the foam material; and a filler composition, wherein the maximum size of each component of the filler composition is smaller than the thickness of the foam material, the filler composition comprising particulate ceramic filler, or particulate calcium carbonate filler, or particulate aluminosilicate clay filler with a disc-shaped morphology, or particulate aluminosilicate clay filler with a hollow tubular morphology, or particulate polymeric silsesquioxane filler, or particulate methylphenyl MQ filler, or a plurality of glass microspheres, or particulate paraffin, or combinations thereof; wherein the curable, filled composition has a viscosity of less than 400,000 centiskJ, or 100,000 to 350,000 centiskJ.

[0104] Sample 2. A curable, filled composition as described in Sample 1, wherein the curable polyorganosiloxane composition further comprises a cocurable polyorganosiloxane containing at least two alkenyl groups and further containing phenyl groups in its main chain, preferably an alkenyl-terminated polyorganosiloxane further containing phenyl groups in its main chain.

[0105] Sample 3. A curable, filled composition as described in Sample 1 or 2, wherein the expanded polymer microspheres are dry.

[0106] Sample 4. A curable, filled composition as described in any of the preceding samples, wherein the expanded polymer microspheres, fillers, or both contain a surface pretreatment.

[0107] Sample 5. A curable, filled composition as described in any of the preceding samples, wherein the filler composition comprises aluminosilicate clay having a hollow tubular nanostructure; or calcium carbonate and aluminosilicate clay having a disc-shaped structure.

[0108] Sample 6. A curable, filled polysiloxane foam layer comprising a curable product of the composition as described in any of the preceding samples, the filled polysiloxane foam layer having a thickness of 20 to 300 micrometers, or 50 to 250 micrometers, or 60 to 200 micrometers.

[0109] Sample 7. The filled polysiloxane foam layer as described in Sample 6 further comprises inhaled polysiloxane oil, inhaled water, inhaled non-reactive solvent, or a combination thereof.

[0110] Sample 8. The filled polysiloxane foam layer as described in Sample 6 or 7, having a compressive flexural strength of 0 to 25 pounds per square inch (0 to 172 kPa), preferably 0 to 15 pounds per square inch (0 to 103 kPa), as determined by ASTM D3574-17 at 25% flexural strength, and a compressive settling of 0 to 5% as determined by ASTM D 3574-95 Test D at 70°C.

[0111] Sample 9. A filled polysiloxane foam layer as described in any of Samples 6 to 8, having a water absorption rate of less than 2% by weight, obtained by heating the sample at 50°C for 24 hours, followed by immersing the sample in water at room temperature for 30 seconds, and a glass transition temperature below -115°C.

[0112] Specimen 10. An electronic article comprising a filled polysiloxane foam layer as described in any one of Specimens 6 to 9.

[0113] Sample 11. An electronic article as described in Sample 10, wherein the article includes a screen of an electronic device, preferably wherein the screen is flexible.

[0114] The aforementioned compositions, methods, and articles may alternatively include, constitute, or substantially constitute any suitable materials, steps, or components disclosed herein. The compositions, methods, and articles may additionally or alternatively be formulated to be free of or substantially free of any materials (or types), steps, or components that are not essential for achieving the function or purpose of the aforementioned compositions, methods, and articles.

[0115] The term "one" does not indicate a quantity limitation, but rather signifies the presence of at least one of the referred to. Unless otherwise expressly stated herein, the term "or" means "and / or". Throughout this specification, references to "one state sample," "another state sample," "partial state sample," etc., indicate that a specific element (e.g., feature, structure, step, or property) described as relating to that state sample is included in at least one state sample described herein, and may or may not be present in other state samples. Furthermore, it should be understood that the elements may be combined in any suitable manner in the various state samples. The term "combination" includes admixtures, mixtures, alloys, reaction products, etc. In the list of alternative types, "combinations thereof" means that the combination may include at least one element from the list with one or more unnamed similar elements. Meanwhile, "at least one of" means that the list contains each element individually, and combinations of two or more elements from the list, and combinations of at least one element from the list with unnamed similar elements.

[0116] Unless otherwise stated herein, all test standards are the most recent valid standards as of the filing date of this application, or, if priority is claimed, the most recent valid standards as of the filing date of the earliest priority application for which such test standard is claimed.

[0117] As used herein, the “diameter” of a particle refers to the diameter of a sphere, or the equivalent diameter obtained from a two-dimensional image analyzed by a particle size analyzer or an electron microscope, such as a transmission electron microscope image analyzed by software such as ImageJ. The designation “D x” indicates the median particle size, where x is the median. For example, D 50 for a 5 µm particle swarm means that 50% of the particles are larger than 5 µm and 50% are smaller than 5 µm. In a sample, “size” refers to the size of a single particle or the average (e.g., mean or median) of a plurality of particles or a swarm of particles.

[0118] When a component, such as a layer, film, block, or substrate, is referred to as being "on" another component, it may be directly on the other component, or there may be intermediate components. Conversely, when a component is referred to as being "directly" on another component, there are no intermediate components.

[0119] The endpoints of all ranges for the same ingredient or property are included, can be independently combined, and include all intermediate points and ranges. For example, the range of "up to 25 wt%, or 5 to 20 wt%" includes the endpoints of the range of "5 to 25 wt%" and all intermediate values, such as 10 to 23 wt%.

[0120] Unless otherwise defined, the technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains.

[0121] All patents, patent applications and other references cited herein are incorporated herein by reference in their entirety. However, if any terminology used in this invention contradicts or conflicts with any terminology used in the incorporated references, the terminology used in this invention shall take precedence over the conflicting terminology from the incorporated references.

[0122] Although specific forms have been described, the applicant or a person skilled in the art may conceive of alternatives, modifications, variations, improvements, and substantial equivalents that are currently unforeseeable or unforeseeable. Therefore, the scope of the appended patent application, as amended thereto, is intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0123] This application claims priority to U.S. Provisional Patent Application No. 63 / 274,094, filed November 1, 2021, the entire contents of which are incorporated herein by reference.

Claims

1. A curable, filled composition for manufacturing a filled polysiloxane foam layer, the composition comprising a curable polysiloxane composition including an alkenyl-substituted polyorganosiloxane, a hydrogenated polyorganosiloxane, and a curing catalyst; a plurality of expanded polymer microspheres having a maximum size smaller than the thickness of the filled polysiloxane foam layer; and a filler composition, wherein the maximum size of each component of the filler composition is smaller than the thickness of the foam material, the filler composition comprising a disc-shaped particulate aluminosilicate clay filler or a hollow tubular particulate aluminosilicate clay filler; wherein the curable, filled composition has a viscosity of less than 400,000 centistokes; wherein the thickness of the filled polysiloxane foam layer is 60 to 200 µm; and wherein the filled polysiloxane foam layer is formed by: The composition is based on the total weight of the filled polysiloxane foam layer: high molecular weight vinyl-terminated polydimethylsiloxane (PDMS), 3 to 7 wt% of lower molecular weight vinyl-terminated poly(methylphenyl)siloxane, 0.5 to 2 wt% of dried, pre-expanded polymer microspheres, and 1 to 3 wt% of kaolin clay; or high molecular weight vinyl-terminated PDMS, 3 to 7 wt% of lower molecular weight vinyl-terminated poly(methylphenyl)siloxane, 0.5 to 2 wt% of dried, silica-treated, pre-expanded polymer microspheres, 2 to 8 wt% of stearic acid-treated calcium carbonate, and 2 to 8 wt% of vinyl-terminated silane-treated hexagonal lamellar kaolin.

2. The curable, filled composition as claimed in claim 1, wherein the curable polysiloxane composition further comprises a cocurable polyorganosiloxane containing at least two alkenyl groups and further containing phenyl groups in its main chain.

3. A curable, filled composition as described in claim 1 or 2, wherein the expanded polymer microspheres are dry prior to addition to the curable, filled composition.

4. A curable, filled composition as described in claim 1 or 2, wherein the expanded polymer microspheres include a surface pretreatment.

5. A filled polysiloxane foam layer comprising a cured product of the composition as described in claim 1 or 2, the filled polysiloxane foam layer having a thickness of 60 to 200 micrometers.

6. The filled polysiloxane foam layer as claimed in claim 5, further comprising an inhaled polysiloxane oil, inhaled water, an inhaled non-reactive solvent, or a combination thereof.

7. The filled polysiloxane foam layer as described in claim 5, having a compression set of 0 to 25 pounds per square inch (0 to 172 kPa) at 25% flexure as determined by ASTM D3574-17, and 0 to 5% at 70°C as determined by ASTM D3574-95 Test D.

8. The filled polysiloxane foam layer as described in claim 5, wherein the water absorption rate is less than 2% by weight, which is achieved by heating the sample at 50°C for 24 hours, followed by immersing the sample in water at room temperature for 30 seconds, and a glass transition temperature below -115°C.

9. An electronic article comprising a filled polysiloxane foam layer as described in claim 5.

10. The electronic article as claimed in claim 9, wherein the article includes a screen of an electronic device.