New air-blown syntactic silicone foam and articles such as secondary battery packs equipped with said foam

Abstract

The present invention relates to a novel air-blown syntactic silicone foam, a method for producing the silicone foam, an article such as a secondary battery pack that includes the air-blown syntactic silicone foam, and a novel recycling method that includes removing the silicone foam from the article and recycling or reusing components of the article.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED PATENT APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 332,895, filed April 20, 2022, which is incorporated by reference in its entirety.

[0002] FIELD OF THEINVENTION The present invention relates to a novel air-blown syntactic silicone foam, a method for producing the silicone foam, an article such as a secondary battery pack that includes the air-blown syntactic silicone foam, and a novel recycling method that includes removing the silicone foam from the article and recycling or reusing components of the article. [Background technology]

[0003] 2. Description of Related Art Silicone elastomers have attracted great interest because the cured silicones have interesting properties such as high elasticity, flexibility at low and high temperatures, high gas permeability, very low glass transition temperature (Tg around -120°C), very good dielectric properties, and good biocompatibility.

[0004] Because silicone foams can achieve significant weight savings, much effort has been expended in recent years on developing methods to introduce porosity without detrimentally affecting the mechanical properties of the silicone cured material.

[0005] For example, new energy storage applications are now being used in transportation, grid-scale energy storage, and green building technologies where thermal insulation is required, making silicone foams, with their excellent thermal insulation properties and excellent moisture resistance, a lightweight alternative to traditional elastomeric encapsulants and sealants.

[0006] Amid this growing trend towards using new energy storage means, lithium-ion battery (LIB) technology is becoming the first choice for energy storage and is the most attractive battery technology due to its high energy density, high specific energy, and excellent rechargeability.

[0007] However, concerns about the availability and supply of key raw materials such as lithium and cobalt that underpin this technology have created a need for either reprocessing capacity or processes to recover either key components or raw materials within articles such as battery packs that contain valuable components such as rechargeable battery cells.

[0008] In fact, currently, reuse is seen as a positive progressive response to the shortening of product life cycles, which is one of the main factors increasing resource pressure and manufacturing burden.

[0009] Reuse can be defined as any operation in which non-waste products or parts are used again for the same purpose for which they were conceived. Reuse takes place before the item is discarded.

[0010] On the other hand, the process of recovering recyclable major components is often termed "reuse preparation", which refers to the inspection, cleaning or repair salvage operations that prepare the discarded product or product parts for reuse without any other pre-treatment.

[0011] The global consumption of secondary battery cells is expected to grow exponentially, and reuse and / or recycling of secondary battery cells is now a major challenge for many industries. Therefore, materials used in battery packs containing secondary battery cells need to enable an easy process for recovering the secondary battery cells for reuse or recycling purposes.

[0012] Additionally, while secondary battery cells used in secondary battery packs offer several advantages over disposable batteries, this type of battery is not without its drawbacks. Generally, most of the disadvantages associated with secondary batteries are due to the battery chemistries employed, as these chemistries tend to be less stable than those used in primary batteries. Secondary battery cells, such as lithium-ion cells, tend to be prone to thermal management issues, as an increase in temperature can lead to exothermic reactions that can further increase the temperature and cause more harmful reactions. During this event, a large amount of thermal energy is rapidly released, heating the entire cell to over 850°C. This increase in temperature in the affected cell also increases the temperature of adjacent cells in the battery pack. If the temperature of the adjacent cells is allowed to increase, the temperature within the cell can become so high and unacceptable that a cascading effect occurs in which the temperature increase in one cell propagates throughout the battery pack. As a result, power from the battery pack is cut off, and the system using the battery pack is likely to suffer extensive collateral damage due to the scale of damage and the associated release of thermal energy. In the worst case scenario, the amount of heat generated is great enough to lead to the combustion of not only the battery but also materials in close proximity to the battery.

[0013] Furthermore, due to the characteristics of lithium-ion batteries, secondary battery packs may operate within an ambient temperature range of -20°C to 60°C. However, even when operating within this temperature range, the capacity and charge / discharge capability of the secondary battery pack may begin to decrease when the ambient temperature drops below 0°C. Depending on the ambient temperature, the life capacity and charge / discharge capability of the battery may decrease significantly when the temperature drops below 0°C. Nevertheless, there are cases where it is unavoidable to use lithium-ion batteries in places where the ambient temperature is outside the optimal ambient temperature range of 20°C to 25°C.

[0014] From the above, in a battery pack assembly with multiple secondary battery cells, a large temperature difference from one cell to the next can occur, which can adversely affect the performance of the battery pack. To extend the life of the entire battery pack, the cells must be below a desired threshold temperature. To enhance the performance of the pack, the temperature difference between the cells of the secondary battery pack needs to be minimized. However, due to the thermal path to the surroundings, different cells reach different temperatures. Furthermore, for the same reason, different cells reach different temperatures during the charging process. Thus, if one cell is hotter than the other cell, its charging or discharging efficiency will be different and it may be charged or discharged faster than the other cell. This leads to a decrease in the performance of the entire pack.

[0015] Many approaches have been adopted to reduce the risk of thermal problems or to reduce the risk of heat propagation. These are described, for example, in US 2012 / 0003508, which describes a battery of lithium electrochemical generators comprising a casing, a number of lithium electrochemical generators housed in the casing, each generator comprising a container, and a rigid flame-retardant foam with closed pores made of an electrically insulating material filling the space between the inner wall of the casing and the free surface of the side wall of the container of each electrochemical generator, the rigid foam covering the free surface of the side wall of the container of each electrochemical generator over a length corresponding to at least 25% of the height of the container. According to one embodiment, the foam is made of a material selected from the group consisting of polyurethane, epoxy, polyethylene, melamine, polyester, formphenol, polystyrene, silicone or mixtures thereof, with polyurethane and mixtures of polyurethane and epoxy being preferred. The expansion of the foam-forming polyurethane resin is described using the following chemical pathway to obtain the foam: (a) Chemical route, i.e., water on isocyanate reacts to generate CO2, which foams the polyurethane; (b) by physical route, i.e., by vaporizing a low boiling liquid under the action of heat generated by the exothermic reaction of the isocyanate with a hydrogen donor compound; or (c) Inject air.

[0016] However, many irritating gases such as isocyanates, nitric oxide and aldehydes are generated during the thermal decomposition of PU-based materials, which have a negative effect on the respiratory system, so alternative technologies are needed to avoid such health problems.

[0017] Another efficient solution involves the use of silicone syntactic foam to insulate the secondary battery pack and further minimize the propagation of thermal runaway, as described in U.S. Patent Application Publication No. 2018 / 223070 filed by Elkem Silicones USA, Inc. This patent application makes extensive use of a silicone potting product provided as silicone syntactic foam.

[0018] While the above solutions for insulating articles such as secondary battery packs could be used in various applications, there remains a need for novel lightweight insulating materials that also allow for an easy process for separating key components such as secondary battery cells from said articles for reuse for recycling purposes. [Prior art documents] [Patent documents]

[0019] [Patent Document 1] US Patent Application Publication No. 2012 / 0003508 [Patent Document 2] US Patent Application Publication No. 2018 / 223070 Summary of the Invention [Problem to be solved by the invention]

[0020] An essential object of the present invention is to provide a novel silicone foam and a method for producing the same.

[0021] Another essential object of the present invention is to provide an article, such as a secondary battery pack, comprising the silicone foam according to the present invention.

[0022] Finally, a final essential object of the present invention is to provide a novel recycling method that allows recycling or reuse of an article and / or some of its component parts. [Means for solving the problem]

[0023] Before the subject disclosure is further described, it should be understood that the disclosure is not limited to the specific embodiments of the disclosure described below, since variations of the specific embodiments may be made and still fall within the scope of the claims. It should also be understood that the terminology used is for the purpose of describing the specific embodiments and is not intended to be limiting. Instead, the scope of the disclosure is defined by the claims.

[0024] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include the plural forms unless the context clearly indicates otherwise. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0025] As used herein, the term "alkenyl" is understood to mean a substituted or unsubstituted unsaturated linear or branched hydrocarbon chain having at least one olefinic double bond, more preferably a single double bond. Preferably, the "alkenyl" group has 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms. The hydrocarbon chain optionally contains at least one heteroatom, such as O, N, S. Preferred examples of "alkenyl" groups include vinyl, allyl and homoallyl groups, with vinyl being particularly preferred.

[0026] As used herein, "alkyl" refers to a saturated, straight or branched hydrocarbon chain, preferably having 1 to 10 carbon atoms, e.g., 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, which may be optionally substituted (e.g., with one or more alkyl groups). Examples of alkyl groups include methyl, ethyl, isopropyl, n-propyl, t-butyl, isobutyl, n-butyl, n-pentyl, isoamyl, 1,1-dimethylpropyl, among others.

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS All these objectives are achieved by the present invention, which in particular relates to a method for producing an air-blown syntactic silicone foam, comprising the steps of: (a) preparing a curable silicone composition X containing hollow microspheres D1; (b) curing the curable silicone composition X under reduced atmospheric pressure to obtain an air-blown syntactic silicone foam.

[0028] The inventors have found through extensive research that air-foamed silicone syntactic foam can be produced without using chemical foaming agents, mechanical foaming processes or physical foaming processes.By adding hollow microspheres D1 to a curable silicone composition and carrying out a curing process under reduced atmospheric pressure, it is surprising to obtain an air-foamed silicone syntactic foam.This foam has the advantage of having a lower thermal conductivity than standard silicone syntactic foams.The foam produced according to the present invention shows a homogeneous cell size distribution and good foam structure.

[0029] Thus, the novel air-blown silicone syntactic foams have low thermal conductivity and may be an excellent alternative when considering new material classes to achieve reduced fuel consumption and CO2 emissions in transportation, for example, as well as to manage the safety of energy storage used in transportation and net-zero energy buildings.

[0030] The process according to the present invention has the advantage of avoiding some of the hurdles encountered in the foaming extrusion process, which is a continuous process involving physical foaming using CO2 as the foaming agent, for example. Indeed, in this physical foaming process, the curable polymer composition is first saturated with CO2 at several to several hundred bars, and foaming is typically induced by a rapid decompression step that then increases the temperature. This results in supersaturation of dissolved CO2 in the curable polymer composition gas mixture, leading to cell nucleation and subsequent rapid cell expansion. Although this technology has been well utilized, challenges remain that are difficult to control, such as CO2 solubility, CO2 diffusivity, and foaming temperature. Thus, the novel process according to the present invention addresses these growing needs for simplification of the processes used in the prior art.

[0031] By "air-blown silicone syntactic foam" is meant a cured silicone gel or cured silicone material containing preformed hollow microspheres and cavities as a binder formed by the novel foaming process of the present invention.

[0032] Without being limited by theory, hollow microspheres are in powder form, which can favor the entrapment of air during compounding and generate inherent air bubbles within the polymer matrix being built. Hollow microspheres can have the effect of stabilizing inherent air bubbles and can increase nucleation efficiency. In fact, a frequently used strategy to increase nucleation cell density relies on increasing the saturation pressure of the physical blowing agent and / or increasing the pressure release rate, for example in physical foaming processes. Thus, the process according to the present invention is much simpler and shows clear advantages over the known blowing processes of the prior art.

[0033] The process of the present invention allows for the production of foams that are lighter than silicone syntactic foams and exhibit improved insulating properties, and therefore can be used in articles such as secondary battery packs to insulate secondary battery cells, with the added advantage that they can be more easily removed compared to silicone syntactic foams, thus avoiding damage to the battery cells.

[0034] In a preferred embodiment, the hollow microspheres D1 are hollow glass microspheres D, more preferably hollow borosilicate glass microspheres.

[0035] In a preferred embodiment, the applied reduced atmospheric pressure is less than 700 mbar, preferably between 700 and 100 mbar, more preferably between 530 and 150 mbar.

[0036] In another embodiment the reduced pressure applied is less than 700mbar, between 700 and 50mbar, between 700 and 140mbar, between 530 and 140mbar, between 360 and 140mbar, between 190 and 140mbar, less than 530mbar or less than 200mbar.

[0037] In another embodiment, the applied reduced atmospheric pressure is 100 to 700 mbar, 100 to 600 mbar, 100 to 550 mbar, 100 to 500 mbar, 100 to 450 mbar, 100 to 400 mbar, 100 to 350 mbar, 100 to 300 mbar, 100 to 250 mbar, 100 to 200 mbar, 150 to 200 mbar, 150 to 250 mbar, 150 to 300 mbar, 150 to 350 mbar, 150 to 400 mbar, 150 to 500 mbar, 150 to 550 mbar, 150 to 600 mbar, 150 to 650 mbar, or 150 to 700 mbar.

[0038] In another preferred embodiment, the reduced atmospheric pressure is applied before the curable silicone composition X is completely cured, for a time that is at least 10% of the gel time of the curable silicone composition X, preferably for a time that is at least 30% of the gel time of the curable silicone composition X, more preferably for a time that is 30% to 70% of the gel time of the curable silicone composition X, and even more preferably for a time that is 45% to 65% of the gel time of the curable silicone composition X.

[0039] The gel time corresponds to the time taken for the reaction mixture to gel and is measured at room temperature (20° C.).

[0040] In another preferred embodiment, the curable silicone composition X further contains 1 to 60 parts by weight, preferably 5 to 40 parts by weight, most preferably 5 to 30 parts by weight, and even more preferably 5 to 20 parts by weight of hollow microspheres D1, relative to 100 parts by weight of the curable silicone composition X.

[0041] Examples of suitable hollow microspheres D1 include hollow glass microspheres or hollow ceramic microspheres.

[0042] Hollow ceramic microspheres, also called cenospheres, are lightweight, inert hollow spheres filled with inert air or gas and are typically produced as a by-product of coal combustion in thermal power plants. Silica and alumina are the main components. Cenospheres vary in color from grey to almost white and have a density of about 0.4-0.8 g / cm. 3 It flows like a liquid and looks like a powder. Suitable cenospheres are either untreated or surface treated with a silane coupling agent such as one or more of 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminopropylmethyldimethoxysilane, or 3-aminopropylmethyldiethoxysilane.

[0043] Hollow glass microspheres, sometimes called "hollow glass beads" or "hollow glass bubbles", are employed in the present invention and function to reduce the density of the silicone foam and play a key role in the air foaming process. Hollow glass microspheres are small hollow spheres of hardened silica (glass) that vary in size and density depending on the grade. They have a shell thick enough to retain structural rigidity. Their hollow nature makes them very light, and their density varies with size and wall thickness. They appear as a white powder in bulk. The main differences between the grades are their size, strength and density, with the strength of the microspheres being expressed in terms of average isotropic crush strength.

[0044] According to one embodiment, the hollow glass beads are hollow borosilicate glass microspheres.

[0045] According to one embodiment, the hollow glass microspheres D have a true density in the range of 0.10 grams per cubic centimeter (g / cc) to 0.75 grams per cubic centimeter (g / cc).

[0046] The term "true density" refers to the quotient obtained by dividing the mass of a sample of hollow glass microspheres by the true volume of the mass of the glass bubbles as measured by a gas pycnometer. "True volume" is the total volume of the glass bubbles, not the bulk volume.

[0047] According to a preferred embodiment, the hollow glass microspheres are selected from: (1) 3M (trademark) Glass Bubble Floated Series (A16 / 500, G18, A20 / 1000, H20 / 1000, D32 / 4500, H50 / 10000 EPX glass bubble products) and 3M (trademark) Glass Bubble Series (K1, K11, K15, S15, S22, K20, K25, S32, S35, K37, XLD3000, S38, S38HS, S38XHS, K46, K42H) sold by 3M The glass bubbles may be formed from a variety of glass bubbles, including, but not limited to, S, S42XHS, S60, S60HS, iM16K, iM30K, A16 / 500, A20 / 1000, H20 / 1000, D32 / 4500, H50 / 10000EPX, HGS2000, HGS3000, HGS4K28, HGS4000, HGS5000, HGS6000, HGS10000, HGS8000X, HGS18000, HGS19K46 glass bubble products. The glass bubbles exhibit various crush strengths ranging from 1.72 megapascals (250 psi) to 186.15 megapascals (27,000 psi) at which 10% by volume of the first plurality of glass bubbles collapse. The true density is from about 0.11 g / cc to about 0.60 g / cc. Other glass bubbles sold by 3M may also be used in accordance with the present invention, such as 3M™ Glass Bubbles-Floated Series, 3M™ Glass Bubbles-HGS Series, and surface treated 3M™ Glass Bubbles. (2) Hollow glass microspheres sold by Potters Industries LLC under the trade names SPHERICEL™ (products such as 110P8, 60P18, 34P30, and 25P45) (exhibiting bulk gravities ranging from about 0.14 g / cc to about 0.49 g / cc) or Q-Cel™ Lightweight (products such as 6014, 6019, 7019, 6019S, 5020, 5020FPS, 7023, 7028, 6036, 7037, 7040S, 6042S, 6048, and 5070S) (exhibiting bulk gravities ranging from about 0.08 g / cc to about 0.42 g / cc).

[0048] The curable silicone composition X is a liquid precursor that cures into a binder such as a silicone gel or a silicone elastomer (sometimes called "silicone rubber"). A suitable curable silicone composition X may be composed of three or four essential components. These components are (i) one or more reactive silicone polymers, (ii) optionally one or more fillers, (iii) a crosslinker, and (iv) a catalyst.

[0049] The curable silicone binder can be obtained by curing either an addition-curable organopolysiloxane composition, a peroxide-curable organopolysiloxane composition, or a condensation-type organopolysiloxane composition.

[0050] Exemplary peroxide-curable organopolysiloxane compositions according to the present invention are preferably defined as comprising essentially: (1) per 100 parts by weight of an organopolysiloxane having at least two alkenyl groups bonded to silicon atoms per molecule, (2) 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, of an organic peroxide that generates free radicals at high temperatures to initiate a crosslinking reaction, and (3) 0.1 to 60 parts by weight, preferably 5 to 40 parts by weight, and most preferably 5 to 30 parts by weight of hollow microspheres D1.

[0051] Organopolysiloxanes having at least two alkenyl groups bonded to silicon atoms per molecule have the same chemical structure as those used in polyaddition curable compositions, but may have a higher viscosity due to the larger number of siloxyl units. Such polymers may contain 0-4% by weight, preferably 0.01-3% by weight, of vinyl groups. These polyorganosiloxane polymers with a viscosity of up to 1,000,000 mPa·s at 25°C are called oils, while those with a viscosity of more than 1,000,000 mPa·s are called gums.

[0052] Suitable organic peroxides include peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters, peroxydicarbonates, benzoyl peroxide, bis(p-chlorobenzoyl)peroxide, bis(2,4-dichlorobenzoyl)peroxide, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butyl perbenzoate, t-butylcumyl peroxide, halogenated derivatives of the above peroxides such as bis(2,4-dichlorobenzoyl)peroxide, 1,6-bis(p-toluoylperoxycarbonyloxy)hexane, 1,6-bis(benzoylperoxycarbonyloxy)hexane, 1,6-bis(p-toluoylperoxycarbonyloxy)butane, and 1,6-bis(2,4-dimethylbenzoylperoxycarbonyloxy)hexane.

[0053] Exemplary condensation-curable organopolysiloxane compositions according to the present invention are preferably defined as comprising essentially: (1) per 100 parts by weight of an organopolysiloxane having at least two hydroxyl end groups, which may be prefunctionalized with a silane to have hydrolyzable groups; (2) 0.1 to 50 parts by weight, preferably 1 to 30 parts by weight, and more preferably 1 to 20 parts by weight, of at least one crosslinking agent, (3) 1 to 60 parts by weight, preferably 5 to 40 parts by weight, most preferably 5 to 30 parts by weight, and even more preferably 5 to 20 parts by weight of hollow glass microspheres D1, and (4) A catalytic amount of a condensation catalyst.

[0054] The curable silicone composition that crosslinks and cures by condensation reaction used in the present invention is well known and commercially available.Such composition is stable during storage in the absence of moisture as a single component, i.e. the composition is packaged in a single package, and can be cured in the presence of moisture, particularly by the moisture provided by ambient air or by the moisture generated in the base during its use.Apart from the single component package, it can also be used as a two-component package (catalyst is separated from the organopolysiloxane with hydroxyl end groups), i.e. the composition is packaged in two separate packages, and cures as soon as these two components are mixed.

[0055] The organopolysiloxane having at least two hydroxyl end groups is preferably an α,ω-dihydroxypolydiorganosiloxane polymer having a viscosity in the range of 50 to 1,000,000 mPa·s at 25° C., which may be end-functionalized with hydrolyzable groups obtained by condensation of a precursor having hydroxyl functional groups with a crosslinkable silane having hydrolyzable groups. The crosslinker is preferably an organosilicon compound having more than two hydrolyzable groups bonded to silicon atoms in one molecule. Examples of crosslinkers include: Silanes of the following general formula: 1 k Si(OR 2 ) (4-k) (Wherein, the symbol R 2 are the same or different and represent an alkyl group having 1 to 8 carbon atoms, such as a methyl, ethyl, propyl, butyl, pentyl or 2-ethylhexyl group, a C3 to C6 oxyalkylene group, and the symbol R 1 represents a linear or branched, saturated or unsaturated aliphatic hydrocarbon-based group, a saturated or unsaturated and / or aromatic monocyclic or polycyclic carbocyclic group, k being equal to 0, 1 or 2; and Partial hydrolysis products of this type of silane.

[0056] Crosslinking agents are silicone market available products.Furthermore, their use in room temperature curable compositions is known and described in French Patent No. 1126411, French Patent No. 1179969, French Patent No. 1189216, French Patent No. 1198749, French Patent No. 1248826, French Patent No. 1314649, French Patent No. 1423477, French Patent No. 1432799 and French Patent No. 2067636.

[0057] The crosslinking agents include, inter alia, alkyltrialkoxysilanes, alkylsilicates and alkylpolysilicates, where the organic group is an alkyl group having 1 to 4 carbon atoms.

[0058] Other examples of crosslinkers that can be used include, in particular, the following silanes: ·Propyltrimethoxysilane; ·Methyltrimethoxysilane; ·Ethyltrimethoxysilane; · Vinyltriethoxysilane; ·Methyltriethoxysilane; · Vinyltriethoxysilane; ·Propyltriethoxysilane; Tetraethoxysilane; Tetrapropoxysilane; 1,2-Bis(trimethoxysilyl)ethane; 1,2-bis(triethoxysilyl)ethane; and Tetraisopropoxysilane, ·CH3Si(OCH3)3;C2H5Si(OC2H5)3;C2H5Si(OCH3)3 ·CH2=CHSi(OCH3)3;CH2=CHSi(OCH2CH2OCH3)3 ·C6H5Si(OCH3)3;[CH3][OCH(CH3)CH2OCH3]Si[OCH3]2 ·Si(OCH3)4;Si(OC2H5)4;Si(OCH2CH2CH3)4;Si(OCH2CH2CH2CH3)4 ·Si(OC2H4OCH3)4;CH3Si(OC2H4OCH3)3;ClCH2Si(OC2H5)3.

[0059] Other examples of cross-linking agents include ethyl polysilicate or n-propyl polysilicate.

[0060] Examples of addition-curable organopolysiloxane compositions suitable for the present invention include compositions comprising the following components: (1) at least one organopolysiloxane A which is linear or branched and has from 2 to 8 carbon atoms and at least two silicon-bonded alkenyl groups per molecule; (2) at least one organohydrogensiloxane B having at least two silicon-bonded hydrogen atoms per molecule, preferably at least three silicon-bonded hydrogen atoms per molecule; (3) at least one hydrosilylation catalyst C; (4) hollow microspheres D1, preferably hollow glass microspheres D; (5) optionally, at least one filler E, (6) optionally at least one cure rate regulator G, which retards the cure rate; (7) optionally, at least one additive H, and (8) Optionally, at least one silicone resin I.

[0061] In a preferred embodiment, organohydrogensiloxane B is a mixture of at least one silicon compound CE containing two telechelic silicon-bonded hydrogen atoms per molecule and no pendant silicon-bonded hydrogen atoms per molecule, and at least one silicon compound XL containing at least three silicon-bonded hydrogen atoms per molecule.

[0062] The term "alkenyl" refers to an acyclic, branched or unbranched monovalent hydrocarbon group having one or more carbon-carbon double bonds. Examples of alkenyl include, but are not limited to, vinyl, allyl, methallyl, propenyl, and hexenyl. The alkenyl group preferably has 2 to 8 carbon atoms.

[0063] In another preferred embodiment, the curable silicone composition is an addition-curable organopolysiloxane composition, defined as comprising: (a) per 100 parts by weight of at least one organopolysiloxane A having at least two silicon-bonded alkenyl groups per molecule, (b) 0.1 to 50 parts by weight of at least one organohydrogensiloxane B having at least two silicon-bonded hydrogen atoms per molecule (i.e., SiH groups, preferably at least three silicon-bonded hydrogen atoms per molecule); (c) 1 to 60 parts by weight, preferably 5 to 40 parts by weight, most preferably 5 to 30 parts by weight, and even more preferably 5 to 20 parts by weight of hollow microspheres D1, (d) a catalytic amount of an addition reaction catalyst C; (e) 0 to 50 parts by weight of at least one filler E, (f) 0 to 20 parts by weight of at least one additive H, (g) optionally, an effective amount of at least one cure rate control agent G that retards the cure rate of the curable silicone composition, and (i) 0 to 50 parts by weight of at least one silicone resin I.

[0064] This embodiment offers several advantages over one-part systems (condensation-type organopolysiloxane compositions), especially in manufacturing environments. Section thickness is not an issue, since it is the catalyst, not moisture, that causes the cure, as in the case of condensation-curable silicones. In fact, they are advantageously used in applications such as potting, sealing, and large castings. Addition-curable organopolysiloxane compositions do not release reaction by-products, so they can be cured in closed environments. Their cure is also greatly accelerated by thermal curing, where the cure does not require heat and can be easily obtained at ambient temperatures of 20°C (±5°C) by adjusting the levels of inhibitors and / or catalysts, a major advantage over peroxide curing, which requires temperatures of 90°C or higher.

[0065] According to another preferred embodiment, the curable silicone composition X comprises: (a) at least one organopolysiloxane A of the formula: [ka] (A) (In the formula, R and R” are C1 to C 30 R and R″ are independently selected from the group consisting of hydrocarbon groups, preferably R and R″ are alkyl groups selected from the group consisting of methyl, ethyl, propyl, trifluoropropyl, and phenyl, most preferably R is a methyl group; R' is C1~C 20 an alkenyl group, preferably R' is selected from the group consisting of vinyl, allyl, hexenyl, decenyl and tetradecenyl, most preferably R' is a vinyl group; n is an integer from 1 to 1000, or from 1 to 500, or from 10 to 500, or from 10 to 400, or from 10 to 350, or from 10 to 300, or from 10 to 250, and is preferably an integer from 5 to 100. (b) at least one silicon compound B containing at least two silicon-bonded hydrogen atoms per molecule, preferably at least three silicon-bonded hydrogen atoms per molecule, most preferably a mixture of two silicon compounds B, one containing two telechelic silicon-bonded hydrogen atoms per molecule and no pendant silicon-bonded hydrogen atoms per molecule (compound CE) and the other containing at least three silicon-bonded hydrogen atoms per molecule, preferably at least three silicon-bonded hydrogen atoms per molecule (compound XL); (c) an effective amount of a hydrosilylation catalyst C, preferably a platinum-based hydrosilylation catalyst C, and (d) hollow microspheres D1, preferably hollow borosilicate glass microspheres; (e) optionally at least one filler E, (f) optionally at least one additive H, (g) optionally, at least one cure rate regulator G that retards the cure rate of the silicone composition, and (i) optionally, at least one silicone resin I.

[0066] According to the above embodiment, the curable liquid silicone composition of the present invention comprises at least one alkenyl-containing organopolysiloxane A having two silicon-bonded alkenyl groups per molecule. In some embodiments, the curable liquid silicone composition of the present invention comprises one or more alkenyl-containing organopolysiloxanes A having two silicon-bonded alkenyl groups per molecule. For example, the curable liquid silicone composition of the present invention can comprise two alkenyl-containing organopolysiloxanes A (A1 and A2) having two silicon-bonded alkenyl groups per molecule.

[0067] In some embodiments, the at least one alkenyl-containing organopolysiloxane A comprises: Two siloxy units of the following formula (A-1): (Alk)(R)2SiO 1 / 2 (A-1) (In the formula, the symbol "Alk" is C2 to C 20 R represents an alkenyl group, such as a vinyl group, an allyl group, a hexenyl group, a decenyl group, or a tetradecenyl group, preferably a vinyl group hydrogen atom, and the symbol R is C1-C 20 an alkyl group, for example a methyl group, an ethyl group, a propyl group, a trifluoropropyl group, or an aryl group, preferably a methyl group; Other siloxy units of the following formula (A-2): (L) g SiO (4-g) / 2 (A-2) (In the formula, the symbol L is C1 to C 20 represents an alkyl group, such as methyl, ethyl, propyl, trifluoropropyl or an aryl group, preferably methyl, the symbol g being equal to 0, 1, 2 or 3, and each L being the same or different.

[0068] In some preferred embodiments, the at least one alkenyl-containing organopolysiloxane A is of formula (1): [ka] (1) (In the formula, n is an integer from 1 to 1000, or from 1 to 500, or from 10 to 500, or from 10 to 400, or from 10 to 350, or from 10 to 300, or from 10 to 250, and is preferably an integer from 5 to 100. R is C1~C 20 an alkyl group, for example a methyl group, an ethyl group, a propyl group, a trifluoropropyl group, or an aryl group, preferably a methyl group; R' is C2~C 20 an alkenyl group, such as a vinyl group, an allyl group, a hexenyl group, a decenyl group, or a tetradecenyl group, preferably a vinyl group; R” is C1~C 20 It may be an alkyl group, for example a methyl group, an ethyl group, a propyl group, a trifluoropropyl group, or an aryl group, preferably a methyl group.

[0069] In a preferred embodiment, the at least one alkenyl-containing organopolysiloxane A is one or more α,ω-(vinyldimethylsilyl)polydimethylsiloxanes, more preferably one or more linear α,ω-(vinyldimethylsilyl)polydimethylsiloxanes.

[0070] All viscosities considered herein correspond in magnitude to the dynamic viscosity measured in a manner known per se with a Brookfield viscometer at 25° C. For fluid products, the viscosity considered herein is the dynamic viscosity at 25° C. known as the “Newtonian” viscosity, i.e. the dynamic viscosity measured in a manner known per se at a sufficiently low shear rate gradient so that the viscosity measured is independent of the velocity gradient.

[0071] In some embodiments, the viscosity of the at least one alkenyl group-containing organopolysiloxane A is from about 50 to about 100,000 mPa·s, from about 5 to about 100,000 mPa·s, from about 100 to about 80,000 mPa·s, from about 100 to about 65,000 mPa·s, from 5 mPa·s to about 5,500 mPa·s, from about 100 to about 40,000 mPa·s, or from about 50 to about 100,000 mPa·s. 0 mPa s, about 100 to about 35,000 mPa s, about 100 to about 30,000 mPa s, about 100 to about 25,000 mPa s, about 100 to about 20,000 mPa s, about 100 to about 15,000 mPa s, about 5 to about 15,000 mPa s, about 5 to about 10,000 mPa s, or about 5 to about 5,000 mPa s.

[0072] In some embodiments, the molecular weight of the at least one alkenyl-containing organopolysiloxane A is from about 1,000 g / mol to about 80,000 g / mol, or from about 10,000 g / mol to about 70,000 g / mol, or from about 10,000 g / mol to about 40,000 g / mol, or from about 10,000 g / mol to about 35,000 g / mol, or from about 10,000 g / mol to about 30,000 g / mol.

[0073] According to a preferred embodiment, the organopolysiloxane A is selected from the group of dimethylpolysiloxanes containing dimethylvinylsilyl end groups.

[0074] A suitable example of silicon compound B is an organohydrogenpolysiloxane containing 10 to 500 silicon atoms, preferably 10 to 250 silicon atoms, in each molecule, which can be contained in the curable liquid silicone composition in an amount of about 0.01% to about 10%, preferably about 0.05% to about 5%, more preferably about 0.1% to about 4% based on the total weight of the composition.

[0075] In some embodiments, the molecular weight of silicon compound B is from about 135 g / mol to about 20,000 g / mol, from about 400 g / mol to about 15,000 g / mol, from about 420 g / mol to about 13,000 g / mol, from about 425 g / mol to about 20,000 g / mol, from about 425 g / mol to about 15,000 g / mol, or from about 425 g / mol to about 12,500 g / mol.

[0076] In a preferred embodiment, the silicon compound B is a mixture of the following compounds: at least one silicon compound B (i.e., compound CE) containing two silicon-bonded telechelic hydrogen atoms per molecule and no silicon-bonded pendant hydrogen atoms per molecule, and at least one silicon compound B (i.e. compound XL) containing at least three hydrogen atoms bonded to silicon per molecule.

[0077] In some embodiments, the organosilicon crosslinker XL containing at least three silicon-bonded hydrogen atoms (silicon hydride or SiH) per molecule / polymer is an organohydrogenpolysiloxane containing 0.45% to 40% by weight SiH, more preferably 0.5% to 35% by weight SiH, even more preferably 0.5% to 15% by weight SiH, or 5% to 12% by weight SiH.

[0078] In some embodiments, the organosilicon crosslinker XL comprises: (i) at least three siloxy units of the following formula (XL-1), which may be the same or different: (H)(Z) e SiO (3-e) / 2 (XL-1) (In the formula, The symbol H represents a hydrogen atom, The symbol Z represents an alkyl group containing 1 to 8 carbon atoms; the symbol e is 0, 1 or 2, preferably e is 1 or 2; and (ii) at least one, preferably 1 to 550, of the siloxy unit of the following formula (XL-2): (Z) g SiO (4-g) / 2 (XL-2) (In the formula, The symbol Z represents an alkyl group containing 1 to 8 carbon atoms; the symbol g is 0, 1, 2 or 3, preferably g is 2; Here, Z in XL-1 and XL-2 may be the same or different.

[0079] In some embodiments, the symbol Z is selected from methyl, ethyl, propyl, and 3,3,3-trifluoropropyl, cycloalkyl, and aryl groups. In some embodiments, Z is a cycloalkyl group selected from cyclohexyl, cycloheptyl, and cyclooctyl. In other embodiments, Z is an aryl group selected from the group consisting of xylyl, tolyl, and phenyl. In other embodiments, Z is a methyl group.

[0080] In a preferred embodiment, the symbol "e" in XL-1 is 1 or 2. In a preferred embodiment, the symbol "g" in XL-2 is 2. In a preferred embodiment, the organosilicon crosslinker XL contains 3 to 60 siloxy units of formula (XL-1) and 1 to 250 siloxy units of formula (XL-2).

[0081] In some embodiments, the organosilicon crosslinker XL contains from 3 to 60 siloxy units of formula (XL-1) and from 1 to 250 siloxy units of formula (XL-2).

[0082] The viscosity of the organosilicon crosslinking agent XL at 25° C. is from about 1 mPa·s to about 10,000 mPa·s, from about 5 mPa·s to about 5,000 mPa·s, from about 5 mPa·s to about 4,000 mPa·s, from about 5 mPa·s to about 3,500 mPa·s, from about 5 to about 2,000 mPa·s, from about 5 mPa.s to about 1,500 mPa.s, from about 5 mPa.s to about 1,000 mPa.s, from about 5 mPa.s to about 500 mPa.s, from about 5 mPa.s to about 350 mPa.s, from about 5 mPa.s to about 150 mPa.s, or from about 5 mPa.s to about 100 mPa.s.

[0083] The curable liquid silicone composition of the present invention may further comprise at least one diorganohydrogensiloxy-terminated polydiorganosiloxane chain extender CE. The at least one diorganohydrogensiloxy-terminated polydiorganosiloxane chain extender CE may be contained in the curable liquid silicone composition in an amount of about 0.1% to about 20% by weight, preferably about 0.5% to about 15% by weight, and more preferably about 0.5% to about 10% by weight, based on the total weight of the composition.

[0084] In some embodiments, the diorganohydrogensiloxy-terminated polydiorganosiloxane CE is of formula (2): [ka] (2) (In the formula, R and R″ are independently C1 to C 20 alkyl groups, preferably R and R″ are independently selected from the group consisting of methyl, ethyl, propyl, trifluoropropyl, and aryl, most preferably R and R″ are methyl; n is an integer ranging from 1 to 500, preferably from 2 to 100, and more preferably from 3 to 50 or 5 to 20.

[0085] In some embodiments, the viscosity of the at least one diorganohydrogensiloxy-terminated polydiorganosiloxane CE is from about 1 to about 500 mPa·s, from about 2 to about 100 mPa·s, from about 4 to about 50 mPa·s, or from about 5 to about 25 mPa·s, or from about 5 to about 20 mPa·s.

[0086] In some embodiments, the molecular weight of the at least one diorganohydrogensiloxy-terminated polydiorganosiloxane CE is from about 100 g / mol to about 5,000 g / mol, preferably from about 250 g / mol to about 2,500 g / mol, or from about 250 g / mol to about 1,500 g / mol, and more preferably from about 500 g / mol to about 1,000 g / mol.

[0087] In some embodiments, the diorganohydrogensiloxy-terminated polydiorganosiloxane CE is of formula (2): [ka] (2) (In the formula, R and R" are independently C1 to C 20 alkyl groups, n is an integer in the range of 1 to 500, preferably an integer in the range of 2 to 100, and more preferably an integer in the range of 3 to 50 or 3 to 20.

[0088] In some embodiments, R and R″ are independently selected from methyl, ethyl, propyl, trifluoropropyl, and phenyl. Preferably, R and R″ are methyl.

[0089] In another embodiment, the diorganohydrogensiloxy-terminated polydiorganosiloxane CE has a weight ratio of silicon chain extender B1 to silicon crosslinker XL of from about 2:1 to about 30:1, from about 2:1 to about 20:1, from about 2:1 to about 15:1, from about 5:1 to about 20:1, from about 5:1 to about 15:1, from about 5:1 to about 15:1, or from about 6:1 to about 15:1.

[0090] According to another preferred embodiment, the viscosity of the organopolysiloxane A at 25°C is from about 5 mPa·s to about 60,000 mPa·s, from about 5 mPa·s to about 50,000 mPa·s, from about 5 to about 40,000 mPa·s, from about 5 to about 35,000 mPa·s, from about 5 to about 30,000 mPa·s, from about 5 to about 25,000 mPa·s, from about 5 to about 20,000 mPa s, from about 5 to about 15,000 mPa s, from about 5 to about 10,000 mPa s, from about 5 to about 5,000 mPa s, or from about 5 to about 3,500 mPa s; the silicon compound CE containing two silicon-bonded telechelic hydrogen atoms per molecule and no silicon-bonded pendant hydrogen atoms per molecule has a viscosity at 25° C. of about 1 to about 500 mPa s, about 2 to about 100 mPa s, about 4 to about 50 mPa s, about 5 to about 25 mPa s, or about 5 to about 20 mPa s; The silicon compound XL containing at least three hydrogen atoms bonded to silicon per molecule has a viscosity at 25° C. of 5 to 2000 mPa·s.

[0091] In preferred embodiments, the components of curable silicone composition X are selected so that its viscosity is from about 100 mPa·s to about 300,000 mPa·s, from about 500 mPa·s to about 100,000 mPa·s, most preferably from 500 mPa·s to 10000 mPa·s, from about 500 mPa·s to about 80,000 mPa·s, from about 100 mPa·s to about 20,000 mPa·s, from about 100 mPa·s to about 15,000 mPa·s, from about 100 mPa·s to about 10,000 mPa·s, from about 500 mPa·s to about 10,000 mPa·s, from about 500 mPa·s to about 5000 Pa·s, from about 500 mPa·s to about 3,500 mPa·s, or from about 500 mPa·s to about 2500 mPa·s.

[0092] According to another preferred embodiment, the viscosities of the organopolysiloxane A and the silicon compound B, which contain at least two hydrogen atoms bonded to silicon per molecule, at 25° C. are selected so that the viscosity of the addition-curable organopolysiloxane composition X at 25° C. is 500 mPa·s to 300,000 mPa·s, about 500 mPa·s to about 100,000 mPa·s, and more preferably about 500 mPa·s to about 80,000 mPa·s, so that the composition can be injected into the battery module casing 102. If the option of pouring a composition into the battery module casing 102 is selected, the components of the addition-curable organopolysiloxane composition X are selected so that its viscosity is about 100 mPa·s to about 20,000 mPa·s, about 100 mPa·s to about 15,000 mPa·s, about 100 mPa·s to about 10,000 mPa·s, about 500 mPa·s to about 10,000 mPa·s, about 500 mPa·s to about 5000 Pa·s, about 500 mPa·s to about 3500 mPa·s, or about 500 mPa·s to about 2500 mPa·s.

[0093] In another preferred embodiment, when about 5% by weight to about 25% by weight or about 5% by weight to about 20% by weight of the hollow microspheres D1 are mixed with other components of the addition-curable organopolysiloxane composition X, the composition X has a viscosity of about 500 mPa·s to about 5,000 mPa·s at 25° C. and can be filled into a container such as a casing for a secondary battery module or a secondary battery pack.

[0094] Examples of hydrosilylation catalysts C include hydrosilylation catalysts such as Karstedt's catalyst as shown in U.S. Pat. No. 3,715,334 or other platinum or rhodium catalysts known in the art, and microencapsulated hydrosilylation catalysts known in the art as seen in U.S. Pat. No. 5,009,957. However, the hydrosilylation catalysts relevant to the present invention can include at least one of the following elements: Pt, Rh, Ru, Pd, Ni, such as Raney nickel, and combinations thereof. The catalyst is optionally bound to an inert or active support. Examples of preferred catalysts that can be used include platinum-type catalysts such as chloroplatinic acid, alcoholic solutions of chloroplatinic acid, complexes of platinum with olefins, complexes of platinum with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, and platinum supported powders. Platinum catalysts are well described in the literature. In particular, platinum complexes with organic products as described in U.S. Patent Nos. 3,159,601, 3,159,602 and 3,220,972 and European Patent Nos. 057,459, 188,978 and 190,530, as well as platinum complexes with vinylated organopolysiloxanes as described in U.S. Patent Nos. 3,419,593, 3,715,334, 3,377,432, 3,814,730 and 3,775,452 to Karlstedt, are preferred. Platinum-type catalysts are particularly preferred.

[0095] The hydrosilylation catalyst C can be added in a catalytic amount (effective amount). The content of the hydrosilylation catalyst is not particularly limited as long as it is an amount sufficient to promote the curing of the composition of the present invention. However, the hydrosilylation catalyst is preferably configured such that the amount of metal atoms is within the range of 0.01 to 500 ppm, 0.01 to 100 ppm, or 0.01 to 50 ppm by mass relative to the organopolysiloxane A component.

[0096] The composition may include one or more fillers E, which may be surface-treated with a treating agent such as a fatty acid or a fatty acid ester, such as a stearic acid ester, or an organosilane, an organosiloxane, or an organosilazane, such as hexamethyldisilazane or a short-chain siloxanediol. The filler may be one or more reinforcing fillers, non-reinforcing fillers (sometimes referred to as "semi-reinforcing fillers"), or a mixture thereof.

[0097] The optional filler E is preferably mineral. It may in particular be siliceous. The siliceous material may function as a reinforcing or semi-reinforcing filler. The reinforcing siliceous filler is selected from colloidal silica, combustion precipitated silica powders, or mixtures thereof. These powders generally have an average particle size of less than 0.1 μm (micrometer) and a mean particle size of less than 30 μm. 2 / g or more, preferably 30 to 350m 2 / g. Semi-reinforcing siliceous fillers such as diatomaceous earth and crushed quartz can also be used. For non-siliceous mineral materials, they function as semi-reinforcing mineral fillers. Examples of these non-siliceous fillers, which can be used alone or in combination, include carbon black, titanium dioxide, aluminum oxide, hydrated alumina, expanded vermiculite, unexpanded vermiculite, calcium carbonate, which may be surface-treated with fatty acids, zinc oxide, mica, talc, iron oxide, barium sulfate, hydrated lime, etc. These fillers generally have a particle size of 0.001 to 300 μm (micrometers) and a BET specific surface area of ​​less than 100 m / g. In practice, mixtures of quartz and silica are used. The fillers may be treated with suitable products.

[0098] Examples of cure rate control agents G, also called inhibitors, are designed to appropriately slow the cure of the formulated silicone. Cure rate control agents are well known in the art, and examples of such materials can be found in U.S. patents. U.S. Patent No. 3,923,705 mentions the use of vinyl-containing cyclic siloxanes. U.S. Patent No. 3,445,420 describes the use of acetylenic alcohols. U.S. Patent No. 3,188,299 shows the effectiveness of heterocyclic amines. U.S. Patent No. 4,256,870 describes alkyl maleates used to control cure. Olefin-based siloxanes can also be used, as described in U.S. Patent No. 3,989,667. Polydiorganosiloxanes containing vinyl groups have also been used, and this technology is described in U.S. Patents Nos. 3,498,945, 4,256,870, and 4,347,346. The preferred inhibitors for this composition are methylvinylcyclosiloxane, 3-methyl-1-butyn-3-ol, and 1-ethynyl-1-cyclohexanol, and most preferably 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, used in amounts of 0.002% to 1.00% of the silicone compound depending on the desired cure rate.

[0099] Preferred curing rate regulators G are selected from: 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane, 3-Methyl-1-butyn-3-ol, or · 1-Ethynyl-1-cyclohexanol (ECH).

[0100] To obtain a longer "gel time" (also called working time or "pot life"), the amount of cure rate control agent G is adjusted to reach the desired "gel time". The concentration of catalyst inhibitor in the silicone composition of the present invention is sufficient to retard the cure of the composition at ambient temperature without preventing or unduly prolonging the cure at elevated temperatures. This concentration will vary widely depending on the particular inhibitor used, the nature and concentration of the hydrosilylation catalyst, and the nature of the organohydrogenpolysiloxane. Inhibitor concentrations as low as 1 mole per mole of platinum group metal may provide satisfactory storage stability and cure rates. In other instances, inhibitor concentrations up to 500 moles or more per mole of platinum group metal may be required. The optimum concentration of a particular inhibitor in a given silicone composition can be readily determined by routine experimentation.

[0101] Examples of additives H include flame retardants, softeners, hardeners, tackifiers, nucleating agents, colorants, pigments, preservatives, rheology modifiers, UV stabilizers, thixotropic agents, surface additives, flow additives, nanoparticles, antioxidants, toughening agents, thermally insulating particles, electrically conductive particles such as carbon black, graphene, iron, copper, single-walled and multi-walled carbon nanotubes (SWT, MWT), aluminum, nickel, silver, metallized glass, lead, zinc and alloys, electrically insulating particles, and combinations or mixtures thereof.

[0102] Silicone resins are well known and commercially available branched organopolysiloxane oligomers or polymers. In their structure, they have the formula RSiO 1 / 2 (M units), R2SiO 2 / 2 (D units), RSiO 3 / 2 (T units), and SiO 4 / 2(Q units), at least one of which is a T or Q unit. The R groups are the same or different and are selected from linear or branched C1-C6 alkyl, hydroxyl, phenyl, 3,3,3-trifluoropropyl. Examples of alkyl groups include methyl, ethyl, isopropyl, t-butyl, and n-hexyl groups. Examples of branched oligomers or organopolysiloxane polymers include MQ resins, MDQ resins, TD resins, and MDT resins.

[0103] In one embodiment, it may be useful to include a silicone resin that is capable of reacting with the reactive components of the curable silicone composition X.

[0104] For example, the curable silicone composition can include an organosilicon resin having at least one hydroxy or alkoxy group, a functional group that is either condensable or hydrolyzable, having at least two different siloxyl units selected from those of the formulas M, D, T, and Q: Siloxyl unit M=(R 0 )3SiO 1 / 2 , Siloxyl unit D = (R 0 )2SiO 2 / 2 , Siloxyl unit R 0 SiO 3 / 2 , and Siloxyl unit Q=SiO 4 / 2 ; In the formula, R 0 represents a monovalent hydrocarbon functional group having 1 to 40 carbon atoms, preferably 1 to 20 carbon atoms, or an OR''' group where R'''=H or an alkyl group having 1 to 40 carbon atoms, preferably 1 to 20 carbon atoms, with the proviso that: Provided that the resin contains at least one T or Q unit.

[0105] The resins preferably have a weight percentage of hydroxy or alkoxy substituents comprised between 0.1 and 10% by weight based on the weight of the resin, and preferably between 0.2 and 5% by weight based on the weight of the resin. Organosilicon resins generally have between about 0.001 and 1.5 OH (hydroxyl groups) and / or alkoxyl groups per silicon atom. These organosilicon resins generally have a structure represented by the formula (R 19 )SiCl, (R 19 )2Si(Cl)2,R 19 It is prepared by cohydrolysis and cocondensation of chlorosilanes such as those with Si(Cl)3 or Si(Cl)4, R 19 The groups are the same or different and are generally selected from linear or branched C1-C6 alkyl, phenyl, and 3,3,3-trifluoropropyl groups. 19 Examples of groups include methyl, ethyl, isopropyl, t-butyl, n-hexyl, among others. Examples of resins include silicone resins of the following types: (OH) , D.T. (OH) , DQ (OH) , D.T. (OH) , MQ (OH) , M.D.T. (OH) , M.D.Q. (OH) , or a mixture thereof.

[0106] Other examples of silicone resins that can react with the reactive components of the curable silicone composition X include silicone resins that contain at least one vinyl group, and can be selected, for example, from the group consisting of the following silicone resins: ·MD Vi Q (wherein the vinyl group is included in the D unit), ·MD Vi TQ (wherein the vinyl group is contained in the D unit), ·MM Vi Q (wherein the vinyl group is included as part of the M unit), ·MM Vi TQ (wherein the vinyl group is included as part of the M unit), ·MM Vi DDVi Q (wherein the vinyl group is included as part of the M and D units), and mixtures thereof, During the ceremony, M Vi = Formula (R) 2 (vinyl) SiO 1 / 2 Siloxyl units D Vi = Formula (R) (vinyl)SiO 2 / 2 Siloxyl units ·T=Formula(R)SiO 3 / 2 Siloxyl units Q = SiO 4 / 2 Siloxyl units ·M=Formula (R)3SiO 1 / 2 Siloxyl units ·D=Formula(R)2SiO 2 / 2 is a siloxyl unit of The R functional groups are the same or different and are monovalent hydrocarbon groups selected from alkyl groups containing 1 to 8 carbon atoms, such as methyl, ethyl, propyl, 3,3,3-trifluoropropyl, and aryl groups, such as xylyl, tolyl, phenyl, etc. Preferably, the R functional group is a methyl group.

[0107] Other examples of silicone resins that can react with the reactive components of the curable silicone composition X include the following silicone resins: M'Q, where the hydrogen atoms bonded to the silicon atom are held by M siloxyl units, MM'Q, where the hydrogen atom bonded to the silicon atom is held by part of M siloxy units; MD'Q, where the hydrogen atom bonded to the silicon atom is held by a siloxyl unit, MDD'Q, where the hydrogen atom bonded to the silicon atom is held by part of a siloxyl unit, MM'TQ (wherein the hydrogen atom is part of the M siloxyl unit), MM'DD'Q (wherein the hydrogen atoms are included as part of the M and D siloxyl units), and mixtures thereof, During the ceremony, M, D, T and Q are as defined above, ·M'=formula R2HSiO 1 / 2 Siloxyl units ·D'=formulaRHSiO 2 / 2 is a siloxyl unit of The R functional groups are the same or different and are monovalent hydrocarbon groups selected from alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, propyl, 3,3,3-trifluoropropyl, etc. Preferably, the R group is a methyl group.

[0108] In another preferred embodiment, the temperature for curing the curable silicone X is from 20°C to 180°C.

[0109] Another object of the present invention relates to an air-blown, syntactic, thermally conductive silicone foam produced according to the process of the present invention.

[0110] According to another advantageous aspect of the present disclosure, there is provided a silicone foam which is air-blown and syntactic, produced according to the above-described inventive process, and 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 0.5 W / (m·K), 0.02 to 0.25 W / (m·K), or 0.02 to 0.10 W / (m·K).

[0111] According to another advantageous aspect of the present disclosure, the silicone foam according to the present invention has a density of 0.1 to 1.0 g / cm 3 , 0.2~0.8g / cm 3 , and even 0.2 to 0.7 g / cm 3 It has a density in the range of

[0112] Another object of the present invention also relates to an article comprising the air-blown syntactic silicone foam according to the present invention. [Brief description of the drawings]

[0113] [Figure 1]FIG. 1 is a top view of a secondary battery pack without a housing top panel 104 having an array of battery cells 103 within a housing bottom panel 102 (electrical connections of the battery cells are not shown). [Diagram 2] FIG. 2 is a perspective view of a secondary battery pack having an array of battery cells 103 disposed inside a housing bottom panel 102 (electrical connections of the battery cells are not shown). [Diagram 3] FIG. 3 is a top view of a battery in a secondary battery pack in which silicone syntactic foam A (air-foamed in accordance with the present invention and referenced as component A in FIG. 3) fills the space between the array of battery cells 103 and the remaining space in the housing bottom panel 102 (electrical connections of the battery cells are not shown). [Figure 4] FIG. 4 is a top view of an array of battery cells 103 in a secondary battery pack covered with silicone syntactic foam A according to the present invention (air-foamed in accordance with the present invention and referenced as component B in FIG. 4 ) that fills the space between the cells and the remaining space in the pack (electrical connections of the battery cells are not shown). [Diagram 5] FIG. 5 is a top view of an array of battery cells 103 designed to provide a honeycomb-like array of battery cells 103 covered with a silicone syntactic foam according to the present invention (electrical connections of the battery cells are not shown). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0114] 1 and 2 show that the battery cells 103 can be in close proximity within the housing bottom panel 102. In one embodiment of the invention, a precursor of Composition X and Material A according to the invention is poured into the bottom panel housing 102 after the array of battery cells has been arranged and installed (104 in FIG. 3) and results in an air-blown silicone syntactic foam when cured according to the invention (105 in FIG. 4).

[0115] In a preferred embodiment, the article is a secondary battery pack comprising: A battery pack housing 101, comprising a housing top panel 104 and a housing bottom panel 102, which when sealed together form a substantially airtight battery pack housing 101; At least one array of battery cells 103 in said housing bottom panel 102, electrically connected to each other and arranged upright with the axes of the cells parallel to each other; In accordance with the present invention, a syntactic silicone foam that is air-foamed as described above, which partially or completely fills the open space of the battery pack housing 101 and / or partially or completely fills the open space within the array of battery cells 103 and / or partially or completely covers the battery cells 103.

[0116] In a preferred embodiment, the array of battery cells 103 are electrically connected to each other, arranged upright with the cell axes parallel to each other, and separated from each other by gaps, and further include a plurality of silicone foam layers disposed in the gaps between the secondary battery cells 103, which are air-foamed and syntactic as described above in accordance with the present invention.

[0117] In another embodiment, the article is a secondary battery pack comprising: At least one battery module casing 102 in which a plurality of secondary battery cells 103 electrically connected to each other are arranged; According to the present invention, a syntactic silicone foam that is air-foamed as described above, wherein the silicone rubber syntactic foam partially or completely fills the open space of the battery module casing 102 and / or partially or completely covers the battery cells 103 and / or partially or completely covers the module casing 102; and Optionally, a lid covering the battery module casing 102.

[0118] In a preferred embodiment, the multiple secondary battery cells 103 are electrically connected to each other and separated from each other by gaps, and further include multiple silicone foam layers that are air-foamed and syntactic as described above in accordance with the present invention and are disposed in the gaps between the secondary battery cells 103.

[0119] In a preferred embodiment, the silicone foam layer is in the form of a sheet having a thickness of 0.5 to 50 mm, preferably 1 to 25 mm, and more preferably 1 to 15 mm.

[0120] In another preferred embodiment, the battery cells 103 are of the lithium ion type.

[0121] According to another preferred embodiment, the secondary battery pack of the present invention further includes a plurality of heat dissipation members disposed at two or more interfaces between the battery cells or under the array 103 of the battery cells, and at least one heat exchange member integrally interconnecting the heat dissipation members, so that heat generated from the battery cells during charging and discharging of the battery cells is removed by the heat exchange member. Even when there is no space between the battery cells or when the space between the battery cells is very small, the battery cells can be cooled more efficiently than the conventional cooling system, and thus the heat dissipation efficiency of the secondary battery pack can be maximized.

[0122] According to another preferred embodiment, the heat dissipation member of the present invention is made of a thermally conductive material exhibiting high thermal conductivity, and the heat exchange member comprises one or more coolant flow passages for flowing a coolant, such as a liquid or gas, therethrough.

[0123] The heat dissipation members according to the present invention are not particularly limited as long as each heat dissipation member is made of a heat conductive material such as a metal plate exhibiting high thermal conductivity.

[0124] Preferably, the heat exchange member includes one or more coolant flow paths for flowing a coolant. For example, by forming a coolant flow path for flowing a liquid coolant such as water in the heat exchange member, a more reliable and superior cooling effect can be obtained compared to a conventional air-cooled structure.

[0125] According to another preferred embodiment, the secondary battery pack of the present invention further comprises a coolant inlet manifold, a coolant outlet manifold, and a plurality of heat exchange tubes extending between the inlet manifold and the outlet manifold as heat dissipation members, the heat exchange tubes being disposed at one or more interfaces between the battery cells and / or under the array 103 of battery cells and having a coolant passing therethrough to exchange heat generated from the battery cells during charging and discharging of the battery cells.

[0126] According to another preferred embodiment, the battery cells 103 are cylindrical cells and are arranged in a number of cell rows to obtain an array of battery cells 103, preferably designed to obtain a honeycomb-shaped array of battery cells.

[0127] In a preferred embodiment, the secondary battery pack further includes a honeycomb-like structure into which the battery cells 103 are inserted and held to form an array of battery cells 103 .

[0128] The battery pack housing 101 is comprised of a housing top panel 104 and a housing bottom panel 102 that, when sealed together, provide a substantially airtight battery pack housing 101. It is configured to hold a plurality of battery cells. The secondary battery pack may further include a ballistic shield mounted underneath the electric vehicle and interposed between the battery pack housing and the driving surface. The ballistic shield may be made of aluminum, aluminum alloy, steel, fiberglass, carbon fiber / epoxy composite, and / or plastic.

[0129] The battery pack housing 101 may be substantially airtight and may be made from aluminum, an aluminum alloy, or steel.

[0130] According to a preferred embodiment, the secondary battery pack according to the present invention is disposed in a vehicle.

[0131] As used herein, the term "vehicle" includes all motor vehicles, such as passenger cars, including sports utility vehicles (SUVs), buses, trucks, various commercial vehicles, various boats and marine vessels, including boats, aircraft, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen vehicles, and other alternative fuel vehicles (e.g., fuels derived from sources other than petroleum). As used herein, a hybrid vehicle is one that has more than one power source, such as both a gasoline-powered vehicle and an electric vehicle.

[0132] In another preferred embodiment, the secondary battery pack according to the present invention is mounted on an automobile.

[0133] In another embodiment, the secondary battery pack according to the present invention is mounted on an all-electric vehicle (EV), a plug-in hybrid vehicle (PHEV), or a hybrid electric vehicle (HEV).

[0134] In another embodiment, the article of the present invention is disposed in a vehicle, aircraft, boat, ship, train, wall unit, or stationary energy storage device.

[0135] Another object of the present invention relates to an article comprising a substrate and at least one covering layer composed of the air-blown syntactic silicone foam according to the present invention.

[0136] Another object of the invention relates to the use of the article according to the invention in marine applications, aerospace applications, aviation applications, ground transport vehicle applications, remotely operated underwater vehicles or autonomous underwater vehicles.

[0137] Another object of the present invention relates to a recycling method comprising the steps of: (a) providing an article according to the present invention as described above, (b) removing the air-blown syntactic silicone foam; (c) recycling or reusing the article and / or parts of the article.

[0138] The recycling method of the present invention is a response to the emerging need for large OEMs to have either rework capabilities or processes to recover key components for many of their devices.

[0139] In fact, a typical lithium-ion battery pack for an EV has an initial service life of around 250,000 km, and once it loses 15%-20% of its initial capacity, the battery becomes unfit for driving, as the capacity loss affects the vehicle's acceleration, driving range, and regenerative capabilities. The possibility of reusing batteries at the end of the vehicle's life cycle, for example as part of a smart grid, in an energy storage system (ESS) for load leveling, or for stationary energy storage to provide residential or commercial power, is an important step towards a circular economy. The potential impact of reusing batteries on life cycle greenhouse gas emissions and the energy usage of the battery in its primary and secondary applications is also an important advantage associated with the use of the recycling method according to the present invention.

[0140] By using the recycling method of the present invention, the silicone syntactic foam of the present invention can be easily and cleanly peeled off from the battery pack, and via the testing infrastructure, batteries with 80-85% of their original capacity can be selected for reuse and the other batteries can be selected for recycling to recover key raw materials such as cobalt, lithium, copper, graphite, nickel, aluminum, manganese, etc.

[0141] Other advantages offered by the present invention will become apparent from the following illustrative examples. EXAMPLES

[0142] (I) Definition of ingredients Organopolysiloxane A1 = polydimethylsiloxane having dimethylvinylsilyl terminal units, the viscosity at 25°C being in the range of 80 mPa.s to 120 mPa.s; Organopolysiloxane A2 = polydimethylsiloxane having dimethylvinylsilyl terminal units, with a viscosity of 500 mPa·s to 650 mPa·s at 25°C; Organopolysiloxane B1 (CE) as a chain extender = polydimethylsiloxane having a dimethylsilylhydride terminal unit, the viscosity of which at 25°C is in the range of 7 mPa.s to 10 mPa.s, and is represented by the following formula: M'D x M' (In the formula, D is a compound of the formula (CH3)2SiO 2 / 2 is a siloxy unit of M' is a compound of the formula (CH3)2(H)SiO 1 / 2 is a siloxy unit of x is an integer between 8 and 11; Organopolysiloxane B2 (XL) as crosslinker, with a viscosity at 25 °C in the range of 18 mPa·s to 26 mPa·s and with the presence of 10 or more SiH reactive groups (average of 16 to 18 SiH reactive groups): poly(methylhydrogeno)(dimethyl)siloxane (α / ω) with intrachain and terminal SiH groups, Hollow glass microsphere filler D1: 3M(trademark) Glass Bubble Series S15 sold by 3M Company, particle size by volume (50%) microns = 55 microns, hydrostatic crushing strength: test pressure 300 psi (2.07 MPa.), true density (g / cc) = 0.15. Hollow glass microsphere filler D2: 3M (trademark) Glass Bubble Series K25 sold by 3M (volume based particle size (50%) microns = 55 microns, isostatic crush strength test pressure 750 psi, true density (g / cc) = 0.25. Hollow glass microsphere filler D3: 3M (trademark) Glass Bubble Series H20 / 1000 sold by 3M, (particle size (50%) by volume microns = microns, hydrostatic crush strength test pressure 1,000 psi, true density (g / cc) = 0.2. Hollow glass microsphere filler D4: 3M(trademark) Glass Bubble Series XLD / 3000 sold by 3M, (particle size (50%) by volume microns = microns, hydrostatic crush strength test pressure 3000 psi, true density (g / cc) = 0.68. Hollow glass microsphere filler D7: 3M™ Glass Bubble K20HS hollow microspheres made of soda lime borosilicate glass, with a true density of 0.20 g / cm 3 , and the isostatic crush strength is 750psi / 52bar. Filler D5MIN-U-SIL® 10, finely divided silica (median diameter 3.4 microns) manufactured by US Silica. Filler D6: Spheriglass®: Solid glass beads (soda-lime glass in the form of microbeads (Spheriglass® A-Glass 3000 available from Potter Industries, Inc.). Filler: D7 Cenosphere ES106 manufactured by Cenostar. ·Cure rate regulator G1: 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane. ·Cure rate regulator G2: 1-ethynyl-1-cyclohexanol (ECH). Curing rate regulator G3-MB: 90% by weight of organopolysiloxane A1 and 10% by weight of curing rate regulator G2 · Catalyst C 10% platinum as Karstedt catalyst in dimethyl vinyl dimer at 350 cS sold by Johnson Matthey. Catalyst C-MB: 98% by weight of organopolysiloxane A1 and 2% by weight of catalyst C. Density is expressed in grams per cubic centimeter (g / cc). The gel time corresponds to the time taken for the reaction mixture to gel and is measured at room temperature (20° C.) using a rotary gel timer. The procedure is as follows: 1. Formulations were prepared by mixing corresponding parts A and B in an aluminum cup. 2. Immediately after mixing (adding part B to part A), start the timer on the rotating gel timer. Mix the resulting mixture manually with a spatula for 90 seconds. 3. Place the alumina cup containing the mixture into a rotating gel timer and secure with a C-clamp. 4. Immediately attach the wire agitator (stop the timer during this operation and restart it immediately after completion). 5. Stir the mixture and record the gel time when the gel timer stops spinning.

[0143] Example 1: Effect of filler type on foaming under reduced pressure

[0144] [Table 1] Table 1. Formulations (weight mixing ratio of part A to part B of each formulation is 1:1).

[0145] Formulations 1, 2 and 3 were prepared in containers by gently mixing (manually mixing with a spatula) the corresponding Part A and Part B, respectively (1:1 mix ratio by weight) for 30 seconds, then each container was placed under reduced atmospheric pressure (maintained within the range of 150-200 mbar) and allowed to cure at room temperature [20°C]. Formulation 1 (used according to the invention) was air-blown to give a silicone syntactic foam exhibiting uniform cell size distribution and good foam structure (density=0.407, thermal conductivity: 0.068 W / mK). Formulation 2 (used as a comparison) containing finely divided silica filler (MIN-U-SIL® 10) did not develop an air-foamed structure under the same curing conditions as formulation 1. Formulation 3, which contained solid glass beads (used as a comparison), did not develop an air-foamed structure under the same curing conditions as formulation 1.

[0146] Example 2: Effect of reduced pressure on foaming

[0147] [Table 2] Table 2. Formulation 1 (weight mix ratio of part A to part B of each formulation is 1:1).

[0148] Formulation 1 was prepared in a vessel by gently mixing (manual mixing with a spatula) the corresponding parts A and B (1:1 mix ratio by weight) in a vessel, and then the resulting formulation was placed under different reduced atmospheric pressures. The vacuum was started at a time corresponding to 30% of the gel time of formulation 1, and curing was carried out at room temperature [20°C]. The quality of the resulting silicone syntactic foams was evaluated according to the homogenous cell size distribution and foam structure. The foams were classified according to the following quality assessments: Bad quality = 0 Good quality = 1 Very good quality = 2 ·Excellent Quality=3 NOTE: Regarding the evaluation, "excellent quality" means higher foam quality compared to "very good quality".

[0149] Example 3: Effect of timing of applying vacuum (% of gel time)

[0150] [Table 3] Table 3. Effect of timing of applying reduced pressure (% of gel time) for Formulation 1 (1:1 weight mix ratio of Part A and Part B).

[0151] Formulation 1 was prepared in a vessel by gentle mixing (manual mixing with a spatula) of the corresponding parts A and B (1:1 mix ratio by weight). Reduced atmospheric pressure (values ​​ranging from 150-200 mbar) was applied at various times, expressed as % of the gel time of formulation 1, and cured at room temperature [20°C]. The quality of the silicone syntactic foams, which are also air-blown, was evaluated according to the homogenous cell size distribution and foam structure. The foams were classified according to the following quality assessment: Bad quality = 0 Medium Quality = 1 Good quality = 2 Very good quality = 3 Excellent quality = 4 Outstanding quality = 5 Note: With regard to the ratings, "Excellent quality" represents a higher foam quality than "Very good quality" and "Outstanding quality" represents a higher foam quality than "Excellent quality." Higher numbers indicate higher quality. The gel time is measured to be 260 seconds.

[0152] Example 4: Effect of hollow glass microspheres loading weight percentage

[0153] [Table 4] Table 4. Formulation (weight ratio of part A and part B: 1:1)

[0154] The formulations listed in Table 4 were prepared in a container by gentle mixing (manual mixing with a spatula) of the corresponding parts A and B (mix ratio of 1:1 by weight). Reduced atmospheric pressure (values ​​ranging from 150 to 200 mbar) was applied at various times, expressed as % of the gel time of the formulation, and cured for 8 minutes at room temperature [20°C]. The quality of the silicone syntactic foams, which are also air-blown, was evaluated according to the homogenous cell size distribution and foam structure. The foams were classified according to the following quality assessment: Bad quality = 0 Medium Quality = 1 Good quality = 2 Very good quality = 3 Excellent quality = 4 Outstanding quality = 5 Note: With regard to the ratings, "Excellent quality" represents a higher foam quality than "Very good quality" and "Outstanding quality" represents a higher foam quality than "Excellent quality." Higher numbers indicate higher quality. The results are shown in Table 5 below.

[0155] [Table 5] Table 5. Formulation (weight ratio of part A to part B: 1:1)

[0156] Example 5: Air-Blown Silicone Synthetic Foam According to the Invention

[0157] [Table 6] Table 6. Formulation (weight ratio of part A to part B: 1:1)

[0158] The formulations listed in Table 6 were prepared in a container by gentle mixing (manual mixing with a spatula) of the corresponding parts A and B (mix ratio of 1:1 by weight). Reduced atmospheric pressure (values ​​ranging from 150-200 mbar) was applied for 55% of the gel time of the formulation and cured at room temperature [20°C]. The quality of the silicone syntactic foams, which are also air-blown, was evaluated according to the homogenous cell size distribution and foam structure. The foams were classified according to the following quality assessment: Bad quality = 0 Medium Quality = 1 Good quality = 2 Very good quality = 3 Excellent quality = 4 Outstanding quality = 5 Note: With regard to the ratings, "Excellent quality" represents a higher foam quality than "Very good quality" and "Outstanding quality" represents a higher foam quality than "Excellent quality." Higher numbers indicate higher quality.

[0159] Example 6: Thermal Conductivity Formulation 1 was prepared according to Example 1 and air-foamed to obtain a silicone syntactic foam (1) with a thermal conductivity of 0.068 W / mK. The same formulation 1 was cured without the procedure of the present invention (no vacuum was applied during curing) to give a silicone syntactic foam (2), which was not air-blown. The measured thermal conductivity was 0.12 W / mK.

[0160] Example 7: Hollow ceramic microspheres

[0161] [Table 7] Table 7. Formulation 10 (1:1 weight ratio of Part A and Part B)

[0162] Formulation 10, as described in Table 7, was prepared in a container by gently mixing (manual mixing with a spatula) the corresponding parts A and B (mix ratio of 1:1 by weight). Reduced atmospheric pressure (values ​​ranging from 150-200 mbar) was applied at 55% of the formulation's gel time and cured at room temperature [20°C] for 8 minutes. Similarly, the quality of the air-blown silicone syntactic foams was evaluated according to homogenous cell size distribution and foam structure. The foams were classified according to the following quality assessment: Bad quality = 0 Medium Quality = 1 Good quality = 2 Very good quality = 3 Excellent quality = 4 Outstanding quality = 5 Note: With regard to the ratings, "Excellent quality" represents a higher foam quality than "Very good quality" and "Outstanding quality" represents a higher foam quality than "Excellent quality." Higher numbers indicate higher quality.

Claims

1. A method for producing an air-blown syntactic silicone foam, comprising the steps of: (a) preparing a curable silicone composition X containing hollow microspheres D1; (b) curing the curable silicone composition X under reduced atmospheric pressure to obtain an air-blown syntactic silicone foam. The method includes:

2. 2. The method of claim 1, wherein the hollow microspheres D1 are hollow glass microspheres D, optionally hollow borosilicate glass microspheres.

3. 2. The process of claim 1, wherein the applied reduced atmospheric pressure is less than 700 mbar, optionally between 700 and 100 mbar, optionally between 530 and 150 mbar.

4. 2. The method of claim 1, wherein reduced atmospheric pressure is applied before the curable silicone composition X is completely cured, at a time that is at least 10% of the gel time of the curable silicone composition X, optionally at a time that is at least 30% of the gel time of the curable silicone composition X, optionally at a time that is between 30% and 70% of the gel time of the curable silicone composition X, and optionally at a time that is between 45% and 65% of the gel time of the curable silicone composition X.

5. The method according to claim 1, comprising, relative to 100 parts by weight of the curable silicone composition X, 1 to 60 parts by weight, optionally 5 to 40 parts by weight, optionally 5 to 30 parts by weight, optionally 5 to 20 parts by weight of hollow microspheres D1.

6. 3. The method of claim 2, wherein the hollow glass microspheres D have a true density in the range of 0.10 grams per cubic centimeter to 0.75 grams per cubic centimeter.

7. The curable silicone composition X is (a) at least one organopolysiloxane A, which is linear or branched and has at least two silicon-bonded alkenyl groups per molecule having from 2 to 8 carbon atoms; (b) at least one organohydrogensiloxane B having at least two silicon-bonded hydrogen atoms per molecule, and preferably at least three silicon-bonded hydrogen atoms per molecule; (c) at least one hydrosilylation catalyst C; (d) hollow glass microspheres D, optionally hollow borosilicate glass microspheres; (e) optionally at least one filler E; (f) optionally at least one cure rate regulator G which retards the cure rate; (g) optionally at least one additive H; (i) optionally, at least one silicone resin I The method of claim 1 , comprising:

8. 8. The method of claim 7, wherein the at least one organohydrogensiloxane B is a mixture of at least one silicon compound CE containing two telechelic silicon-bonded hydrogen atoms per molecule and no pendant silicon-bonded hydrogen atoms per molecule, and at least one silicon compound XL containing at least three silicon-bonded hydrogen atoms per molecule.

9. 8. The method of claim 7, wherein the components of the curable silicone composition X are selected such that its viscosity is from 500 mPa·s to 20,000 mPa·s, optionally from 500 mPa·s to 10,000 mPa·s.

10. 2. The method of claim 1, wherein the temperature for curing the curable silicone X is from 20°C to 180°C.

11. 2. A syntactic silicone foam obtained by air-blown according to claim 1.

12. 12. An article comprising the air-blown syntactic silicone foam of claim 11.

13. 13. The article of claim 12, which is a secondary battery pack comprising: a battery pack housing comprised of a housing top panel and a housing bottom panel that, when sealed together, provide a substantially airtight battery pack housing; at least one array of battery cells within said housing bottom panel, said battery cells being electrically connected to each other and arranged upright with axes of said cells parallel to each other; - An air-blown syntactic silicone foam that partially or completely fills the open space of the battery pack housing and / or partially or completely fills the open space within the array of battery cells and / or partially or completely covers the battery cells.

14. 13. The article of claim 12, which is a secondary battery pack comprising an array of battery cells electrically connected to each other and arranged upright with the axes of the cells parallel to each other, separated from each other by gaps, and further comprising a plurality of air-blown syntactic silicone foam layers disposed in the gaps between the secondary battery cells.

15. 13. The article of claim 12, which is a secondary battery pack comprising: At least one battery module casing in which a plurality of secondary battery cells electrically connected to each other are arranged; - an air-blown syntactic silicone foam, which partially or completely fills the open space of the battery module casing and / or partially or completely covers the battery cells and / or partially or completely covers the module casing; and - Optionally, a lid covering the casing of the battery module.

16. 16. The article of claim 15, which is a secondary battery pack, comprising a plurality of secondary battery cells electrically connected to each other and separated from each other by gaps, and further comprising a plurality of air-blown syntactic silicone foam layers disposed in the gaps between the secondary battery cells.

17. The article of claim 14, wherein the silicone foam layer is in sheet form having a thickness of 0.5 to 50 mm, optionally 1 to 25 mm, optionally 1 to 15 mm.

18. 14. The article of claim 13, wherein the battery cells are of the lithium ion type.

19. The article of claim 13 , wherein the secondary battery cell is pouch-shaped, prismatic, or cylindrical.

20. 13. The article of claim 12, wherein the article is disposed in a vehicle, aircraft, boat, watercraft, train, wall unit, or stationary energy storage device.

21. 13. The article of claim 12, comprising a substrate and at least one covering layer comprised of air-blown syntactic silicone foam.

22. 13. An article of manufacture comprising the article of claim 12 in a marine application, an aerospace application, an aeronautical application, a ground vehicle application, a remotely operated underwater vehicle, or an autonomous underwater vehicle.

23. Recycling methods include the following steps: (a) providing an article according to claim 12; (b) removing the air-blown syntactic silicone foam; (c) recycling or reusing said article and / or parts of said article.

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