WO2025216870A1

WO2025216870A1 - Fire-resistant nonexpanding low density potting adhesive for temperature sensitive electronic devices and batteries

Info

Publication number: WO2025216870A1
Application number: PCT/US2025/021226
Authority: WO
Inventors: Mehrafshan GHOLI JAFARI; Nicholas A. BEWICK; Martin Hornung; Wanli Cheng; Christy Lee STINE; Sarah Lily CHERRY; Michael D. HARNADEK
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 2024-04-11
Filing date: 2025-03-25
Publication date: 2025-10-16
Anticipated expiration: 2026-10-11

Abstract

The present disclosure relates to a two-part system (e.g. a two-part potting compound system), processes for its preparation, and uses of thereof as a potting compound in, e.g., temperature sensitive electronic devices and batteries.

Description

Attorney Docket No.: 2023P00345WO_shl FIRE-RESISTANT NONEXPANDING LOW DENSITY POTTING ADHESIVE FOR TEMPERATURE SENSITIVE ELECTRONIC DEVICES AND BATTERIES Field of the Invention [0001] The present invention relates to a two-part system (e.g. a two-part potting compound system), processes for its preparation, and uses thereof as a potting compound in, e.g., temperature sensitive electronic devices and batteries. Background of the Invention [0002] Thermally insulating materials are a critical element of the overall safety strategies incorporated by many electric vehicle (EV) manufacturers. Failure in an electric component, due primarily to automotive collisions and overcharging, can initiate thermal propagation throughout the entire system. These catastrophic failures may lead to fire, causing harm, death, and property damage. Thermal insulation within the battery compartment or box is one of the key methods in preventing or slowing thermal propagation events and minimizing destructive fires. [0003] Foaming polyurethane (foaming PU) adhesives are the prevalent solution to low density adhesive formulations. However, polyurethanes tend to fail in adhesion to aluminum, and often show poor flame resistance. [0004] The use of glass bubbles in adhesive formulations is also an approach. However, glass bubbles tend to increase viscosity and also drop the lap shear strength at a certain filling percentage. There is therefore a limit to how far density can be decreased using only glass bubbles, without jeopardizing other mechanical and physical properties of the adhesive, such as elongation and less toughened material. [0005] U.S. Patent No.11,114,719 describes a battery module that includes an electric cell and a potting compound associated with the electric cell. The potting compound is a foam that includes a flame-retardant compound, a first compound having an isocyanate reactive compound and water, and a second component having an isocyanate compound. [0006] In general, potting is the process of partially or completely filling or embedding an enclosure with a material for the purpose of maintaining objects within the enclosure in spatial relationship to one another and to the enclosure. Potting may be used to provide resistance to Attorney Docket No.: 2023P00345WO_shl shock and vibration. Certain compositions used for potting may be designed for creating a seal against moisture, solvents, and corrosive agents. [0007] Materials used to form potting compounds vary in hardness from very soft to hard and rigid and are designed to withstand various environments. Potting compounds for use in potting electric cells may be designed to provide mechanical stability and shock tolerance, for example for battery modules intended for use in a vehicle. [0008] A potting compound that provides mechanical stability to an electric cell while adding minimal weight to the battery module is desired. A potting compound for use in a battery module that provides mechanical stability to an electric cell, has a low density and is flame resistant is also desired. The present invention addresses such needs. Summary of the Invention [0009] The present invention provides a two-part system that may be used, e.g., to provide thermal insulation between battery cells to slow or prevent thermal propagation. The two-part systems described herein exhibit low thermal conductivity and low viscosity. The low viscosity enhances the flowability, which consequently facilitates proper dispersion of the adhesive, a complete fill of the battery package, and lessens occurrence of voids and defects. The two-part systems described herein also exhibit high Young’s modulus, high lap shear strength on aluminum, and high elongation, as well as mitigating thermal propagation and passing crucial flammability and structural tests. [0010] In the two-part systems described herein, low-density and low thermal conductivity is achieved via an increase of homogeneous voids or hollow buffers throughout the material by using thermoplastic microspheres and/or glass bubbles in one or both parts of the two-part system (e.g., two-part potting compound system). Expansion of the thermoplastic microspheres results in a homogeneous liquid emulsion that can be further stabilized using shear thinning gelling agents. The low-density minimizes the weight of potting material while maintaining desired adhesion properties. [0011] The two-part systems described herein may exhibit one or more of the following exemplary properties: • Low thermal conductivity (e.g., < 0.2 W/mK). • Low viscosity (e.g., < 1500 cps at 45 C). Attorney Docket No.: 2023P00345WO_shl • Flame resistance. • High lap shear strength on aluminum (e.g., > 12 MPa). • High Young’s modulus (e.g., > 100 MPa). [0012] In exemplary embodiments of the two-part systems described herein: • The epoxy-based adhesives allow for low-exotherm curing, which is advantageous for systems that are temperature sensitive. • The low density of the potting material improves light-weighting of final products and devices and reduces the cost of shipments and overall product. • The high thermal capacity and low thermal conductivity achieved by the presence of the voids as a result of the high volume of bubbles incorporated in the systems is advantageous in providing thermal insulation and avoiding heat propagation in temperature sensitive devices. • The high Young’s modulus and lap shear strength on aluminum are also desired properties for potting materials. • The flame resistance observed for the potting materials described herein allows for development and production of safer potting adhesives. [0013] Accordingly, in one aspect, the present invention relates to a two-part system (e.g., a two- part potting compound system) comprising (A) a first part (Part A) comprising: (i) one or more epoxy resins; (ii) one or more liquid flame-retardants (e.g., one or more compatible liquid flame retardants); (iii) optionally, a first plurality of expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives (such as, e.g., adhesion promoters, diluents, fillers, plasticizers, solid flame retardants, or any combination thereof); and (B) a second part (Part B) comprising: (i) one or more curing agents; (ii) one or more liquid flame-retardants (e.g., one or more compatible liquid flame retardants); Attorney Docket No.: 2023P00345WO_shl (iii) optionally, a second plurality of expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives (such as, e.g., adhesion promoters, diluents, fillers, plasticizers, solid flame retardants, or any combination thereof); wherein (a) Part A has a density ranging from about 0.75 to about 1.25 g/mL, when measured in accordance with ASTM D1475 at 23^o C, (b) Part B has a density ranging from about 0.50 to about 0.90 g/mL, when measured in accordance with ASTM D1475 at 23^o C, and (c) at least one of Part A and Part B comprises a plurality of expanded thermoplastic microspheres. [0014] In one embodiment of any of the two-part systems described herein, Part A comprises a plurality of expanded thermoplastic microspheres. [0015] In one embodiment of any of the two-part systems described herein, Part B comprises a plurality of expanded thermoplastic microspheres. [0016] In one embodiment of any of the two-part systems described herein, both Part A and Part B comprise a plurality of expanded thermoplastic microspheres. [0017] In another aspect, the present invention relates to a kit (e.g., a kit for forming a two-part potting compound system) comprising: (A) a first part (Part A) comprising: (i) one or more compatible epoxy resins; (ii) one or more compatible liquid flame-retardants (e.g., one or more compatible liquid flame retardants); (iii) optionally, a first plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives (such as, e.g., adhesion promoters, diluents, fillers, plasticizers, solid flame retardants, or any combination thereof); wherein Attorney Docket No.: 2023P00345WO_shl (a) if Part A comprises non-expanded thermoplastic microspheres, components listed in (A) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part A, if present, are heated (in a thermal process) to a temperature (e.g., an expansion temperature between T_onset and T_peak of expansion) at which expansion of the non-expanded thermoplastic microspheres occurs (e.g., for about 1 to about 3 hours); (b) Part A is then cooled (e.g., cooled to room temperature) and any components used in Part A that are incompatible with the thermal process of (a) above (such as, e.g., thermally non-compatible epoxy resins, flame retardants, solid filler additives, and a further first plurality of expanded thermoplastic microspheres and/or hollow glass microspheres, or any combination of any of the foregoing), are added; wherein the resulting Part A has a density ranging from about 0.75 to about 1.25 g/mL, when measured in accordance with ASTM D1475 at 23^o C; and (B) a second part (Part B) comprising: (i) one or more compatible curing agents; (ii) one or more compatible liquid flame-retardants (e.g., one or more compatible liquid flame retardants); (iii) optionally, a second plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives (such as, e.g., adhesion promoters, diluents, fillers, plasticizers, solid flame retardants, or any combination thereof); wherein (a) if Part B comprises non-expanded thermoplastic microspheres, components listed in (B) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part B, if present, are heated (in a thermal process) to a temperature (e.g., an expansion temperature between T_onset and T_peak of expansion) at which expansion of the non-expanded thermoplastic microspheres occurs (e.g., for about 1 to about 3 hours); (b) Part B is then cooled (e.g., cooled to room temperature) and any components used in Part B that are incompatible with the thermal process of (a) above (such as, e.g., thermally non-compatible epoxy resins, flame retardants, solid filler additives, and a further first plurality Attorney Docket No.: 2023P00345WO_shl of expanded thermoplastic microspheres and/or hollow glass microspheres, or any combination of any of the foregoing), are added; wherein the resulting Part B has a density ranging from about 0.50 to about 0.90 g/mL, when measured in accordance with ASTM D1475 at 23^o C, and wherein at least one of Part A and Part B comprises expanded thermoplastic microspheres. [0018] In another aspect, the present invention relates to a method for preparing a two-part system (e.g., a two-part potting compound system), the method comprising: (a) preparing a first part (Part A) by mixing: (i) one or more compatible epoxy resins; (ii) one or more compatible liquid flame-retardants (e.g., one or more compatible liquid flame retardants); (iii) optionally, a first plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives (such as, e.g., adhesion promoters, diluents, fillers, plasticizers, solid flame retardants, or any combination thereof); (b) if Part A comprises non-expanded thermoplastic microspheres, components listed in (A) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part A, if present, are heated (in a thermal process) to a temperature (e.g., an expansion temperature between T_onset and T_peak of expansion) in order to expand the first plurality of non-expanded thermoplastic microspheres; (c) cooling the mixture of step (b) (e.g., to room temperature), and, optionally, adding the remainder of components used in Part A that are incompatible with the thermal process (such as, e.g., thermally non-compatible epoxy resins, liquid flame retardants, and all solid filler additives, a further first plurality of expanded thermoplastic microspheres and/or hollow glass microspheres, or any combination of any of the foregoing), thereby forming the first part (Part A); wherein the resulting Part A has a density ranging from about 0.75 to about 1.25 g/mL, when measured in accordance with ASTM D1475 at 23^o C; (d) preparing a second part (Part B) by mixing: (i) one or more compatible curing agents; Attorney Docket No.: 2023P00345WO_shl (ii) one or more compatible liquid flame-retardants (e.g., one or more compatible liquid flame retardants); (iii) optionally, a second plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives (such as, e.g., adhesion promoters, diluents, fillers, plasticizers, solid flame retardants, or any combination thereof); (e) if Part B comprises non-expanded thermoplastic microspheres, components listed in (B) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part B, if present, are heated (in a thermal process) to a temperature (e.g., an expansion temperature between T_onset and T_peak of expansion) in order to expand the second plurality of non-expanded thermoplastic microspheres; (f) cooling the mixture of step (e), (e.g., to room temperature), and, optionally, adding the remainder of components used in Part B that are incompatible with the thermal process (such as, e.g., thermally non-compatible epoxy resins, liquid flame retardants, and all solid filler additives, a further first plurality of expanded thermoplastic microspheres and/or hollow glass microspheres, or any combination of any of the foregoing), thereby forming the second part (Part B); wherein the resulting Part B has a density ranging from about 0.50 to about 0.90 g/mL, when measured in accordance with ASTM D1475 at 23^o C, and wherein at least one of Part A and Part B comprises a plurality of expanded thermoplastic microspheres. [0019] In another aspect, the present invention relates to a method for forming a battery module, wherein the battery module comprises an electric cell and a cavity, the method comprising: (a) preparing a first part (Part A) by mixing: (i) one or more compatible epoxy resins; (ii) one or more compatible liquid flame-retardants (e.g., one or more compatible liquid flame retardants); (iii) optionally, a first plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and Attorney Docket No.: 2023P00345WO_shl (iv) optionally, one or more additional additives (such as, e.g., adhesion promoters, diluents, fillers, plasticizers, solid flame retardants, or any combination thereof); (b) if Part A comprises non-expanded thermoplastic microspheres, components listed in (A) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part A, if present, are heated (in a thermal process) to a temperature (e.g., an expansion temperature between T_onset and T_peak of expansion) in order to expand the first plurality of non-expanded thermoplastic microspheres; (c) cooling the mixture of step (b) (e.g., to room temperature), and, optionally, adding the remainder of components used in Part A that are incompatible with the thermal process (such as, e.g., thermally non-compatible epoxy resins, liquid flame retardants, and all solid filler additives, a further first plurality of expanded thermoplastic microspheres and/or hollow glass microspheres, or any combination of any of the foregoing), thereby forming the first part (Part A); wherein the resulting Part A has a density ranging from about 0.75 to about 1.25 g/mL, when measured in accordance with ASTM D1475 at 23^o C; (d) preparing a second part (Part B) by mixing: (i) one or more compatible curing agents; (ii) one or more compatible liquid flame-retardants (e.g., one or more compatible liquid flame retardants); (iii) optionally, a second plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives (such as, e.g., adhesion promoters, diluents, fillers, plasticizers, solid flame retardants, or any combination thereof); (e) if Part B comprises non-expanded thermoplastic microspheres, components listed in (B) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part B, if present, are heated (in a thermal process) to a temperature (e.g., an expansion temperature between T_onset and T_peak of expansion) in order to expand the second plurality of non-expanded thermoplastic microspheres; Attorney Docket No.: 2023P00345WO_shl (f) cooling the mixture of step (e), (e.g., to room temperature), and, optionally, adding the remainder of components used in Part B that are incompatible with the thermal process (such as, e.g., thermally non-compatible epoxy resins, liquid flame retardants, and all solid filler additives, a further first plurality of expanded thermoplastic microspheres and/or hollow glass microspheres, or any combination of any of the foregoing), thereby forming the second part (Part B); wherein the resulting Part B has a density ranging from about 0.50 to about 0.90 g/mL, when measured in accordance with ASTM D1475 at 23^o C; (g) mixing Part A and Part B in the cavity; (h) curing the mixture of Part A and Part B in the cavity, wherein at least one of Part A and Part B comprises expanded thermoplastic microspheres. [0020] In another aspect, the present invention relates to a method for forming a battery module, wherein the battery module comprises an electric cell and a cavity, the method comprising (a) adding a two-part system of any of the embodiments described herein to the cavity; and (b) curing the two-part system in the cavity. [0021] In any of the embodiments described herein, the two-part system is a potting compound that is low density and is flame retardant. [0022] In one embodiment of any of the systems described herein, the potting compound has at least a V2 level flame resistance as measured by the UL 94 Test for Flammability of Plastics. [0023] In one embodiment of any of the systems described herein, the potting compound has at least a V1 level flame resistance as measured by the UL 94 Test for Flammability of Plastics. [0024] In one embodiment of any of the systems described herein, the potting compound has at least a V0 level flame resistance as measured by the UL 94 Test for Flammability of Plastics. [0025] The potting compounds described herein may be formed from a two-part system (e.g., a two-part potting composition) that is applied as a liquid, mixes and cures to form the potting compound. The potting composition has sufficient flowability before curing to allow the potting composition to be applied as a liquid around an electric cell and then settle at a substantially level height around the electric cell. The potting compositions disclosed herein can be applied as a liquid and flow around the electric cell and through the spaces defined between adjacent electric cells before curing to form the potting compound. Attorney Docket No.: 2023P00345WO_shl [0026] The potting compound is useful for potting an electric cell and forming a battery module that is lightweight. The potting compound is useful to pot an electric cell and provide mechanical stability and flame retardancy after curing. Brief Description of the Drawings [0027] FIG.1 is a flow chart depicting an exemplary, non-limiting, process for preparing the two-part systems described herein. [0028] FIG 2. shows the change in density of a thermoplastic microsphere in an exemplary Part B formulation as described herein (containing two amine curing agents) as the temperature is increased. Detailed Description of the Invention [0029] As used herein, the term “compatible” with respect to an ingredient of the systems described herein means an ingredient of the system that does not negatively affect expansion of a blowing agent in the thermoplastic microspheres described herein, and/or does not cause a shell of the microsphere to burst before, during or following expansion, and/or does not require inert atmosphere due to it reaching flash point during a thermal process, and/or does not self-degrade and/or become unstable during the heating process. [0030] As used herein, the term “non-compatible” with respect to an ingredient of the systems described herein means an ingredient of the system that negatively affects expansion of a blowing agent in the thermoplastic microspheres described herein, and/or causes a shell of the microsphere to burst before, during or following expansion, and/or requires inert atmosphere due to reaching flash point during thermal process, and/or decomposes or self-degrades due to thermal instability during a thermal expansion process of the thermoplastic microspheres. [0031] As used herein, the term “T_onset” means the temperature at which expansion of the thermoplastic microspheres begins. [0032] As used herein, the term “T_peak” means the temperature at which expansion of the thermoplastic microsphere is at a maximum, and/or the temperature at which the size of the expanded microsphere is such that it provides a minimum density to the system in which it is Attorney Docket No.: 2023P00345WO_shl present, and/or the temperature at which the time to reach maximum expansion of thermoplastic microspheres and minimum density is optimal. [0033] As used herein, the term “blowing agent” refers to an agent (e.g., a gas such as nitrogen or carbon dioxide, or a hydrocarbon) present in a thermoplastic microsphere that expands upon heating and causes expansion of the thermoplastic microsphere as the polymer comprising thermoplastic microsphere reaches T_g (e.g., upon heating the microsphere to T_onset). [0034] As used herein, the term “about” when referring to a number or a numerical range means that the number or numerical range referred to is an approximation within experimental variability (or within statistical experimental error), and thus the number or numerical range may vary from, for example, between 1% and 15% of the stated number or numerical range. [0035] As used herein, the term “comprising” (and related terms such as “comprise” or “comprises” or “having” or “including”) includes, but is not limited to, those embodiments, for example, an embodiment of any composition of matter, composition, method, or process, or the like, that “consist of” or “consist essentially of” the described features. [0036] Any use of the word “or” herein is intended to be inclusive and is equivalent to the expression “and/or,” unless the context clearly dictates otherwise. As such, for example, the expression “A or B” means A, or B, or both A and B. Similarly, for example, the expression “A, B, or C” means A, or B, or C, or any combination thereof. [0037] All ranges disclosed herein are inclusive of the recited endpoint and independently combinable (for example, the range of "from 2 to 10" is inclusive of the endpoints, 2 and 10, and all the intermediate values). The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value; they are sufficiently imprecise to include values approximating these ranges and/or values. As used herein, approximating language may be applied to modify any quantitative representation that may vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about," may not be limited to the precise value specified, in some cases. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. The modifier "about" should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression "from about 2 to about 4" also discloses the range "from 2 to 4." The term "about" may refer to plus or minus Attorney Docket No.: 2023P00345WO_shl "about 1" may mean from 0.9-1.1. Other meanings of "about" may be apparent from the context, such as rounding off, so, for example "about 1" may also mean from 0.5 to 1.4. Epoxy Resins [0038] In certain embodiments of any of the systems, kits and methods described herein, the one or more epoxy resins is selected from aliphatic epoxy resins, aromatic epoxy resins, and any combination thereof. [0039] Suitable epoxy resins for use in any of the systems, kits and methods described herein include, but are not limited to, EPON 862 and EPON 828. [0040] Epoxy modifiers and diluents such as, e.g., Araldite DY-31 CH and Heloxy modifier 107, may also be used. [0041] The epoxy resin is present in the first part (Part A) of the system. The epoxy resin may be present in Part A at a weight percent from greater than zero percent, about 10 percent, about 20 percent, or about 30 percent, to about 40 percent, about 50 percent, or about 60 percent, about 70 percent, about 80%, or a weight percent between any pair of the foregoing values, based on the total weight of Part A. For example, the epoxy resin may be present in Part A in about 50 to about 80 % w/w or between about 60 and about 70 % w/w of Part A. Flame Retardants [0042] The systems and kits described herein include one or more flame retardants. The flame retardant is preferably a liquid at room temperature when used for thermal expansion of thermoplastic microspheres. In some embodiments, each part of the system includes a fire retardant or includes two or more flame retardants. The flame retardant(s) may be present in one or both of the parts (Part A and/or Part B) of the system. In some embodiments, the first part of the system (Part A) may include a first flame retardant and the second part of the system (Part B) may include a second flame retardant. [0043] Suitable liquid flame retardants for use in any of the embodiments described herein may include those having a viscosity from about 30 cP, about 40 cP, about 100 cP, about 200 cP, about 300 cP or about 400 cP, to about 600 cP, about 700 cP, about 800 cP, or about 900 cP, or about 2000 cP, or a viscosity between any pair of the foregoing values at room temperature (between about 25° C and about 35° C). Liquid flame retardants having alternative viscosities are further contemplated. Attorney Docket No.: 2023P00345WO_shl [0044] Preferred liquid flame retardants include those having a viscosity no greater than about 600 cP at room temperature. For example, preferred liquid flame retardants include those having a viscosity from about 60 cP, or about 80 cP, or about 100 cP, to about 150 cP, about 200 cP, about 250 cP, about 300 cP, or about 400 cP, or a viscosity between any pair of the foregoing values at room temperature, although flame retardants having additional viscosities are further contemplated. In one embodiment, the liquid flame retardant(s) have a viscosity of between about 250 and about 400 cP at 25º C. The viscosity may be measured using, e.g., a Brookfield Viscometer with PP25 plates at 25^oC using ASTM D4440, [0045] In some embodiments, the flame retardant may include non-hazardous halogen-free organic phosphates. In certain preferred embodiments, the flame retardant(s) are halogen-free phosphorus-based liquid flame retardants and halogen-free solid flame retardants. [0046] The flame retardant may include other examples of brominated organic compounds including, for example, brominated diols, brominated mono-alcohols, brominated ethers, brominated phosphates, and combinations thereof. Suitable brominated organic compounds may include tetrabromobisphenol-A, hexabromocyclododecane, poly(pentabromobenzyl acrylate), pentabromobenzyl acrylate, tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tribromophenol, dibromoneopentyl glycol, tribromoneopentyl alcohol, tris(tribromoneopentyl) phosphate, and 4,4′-isopropylidenebis[2-(2,6-dibromophenoxy) ethanol]. [0047] In another embodiment, the flame retardant is selected from trichloropropyl phosphate (TCPP), triethyl phosphate (TEP), diethyl ethyl phosphate (DEEP), a brominated polyether polyol, brominated phthalic anhydride, ammonium polyphosphate, encapsulated red phosphorus, or any mixture thereof. [0048] In some embodiments, a suitable commercially available liquid flame retardant may be the halogen-free flame retardant series sold under the trade name ANTIFLAME^® (from M Chemical). [0049] The flame retardant is present in at least one of the first or second parts of the system. The flame retardant component may be present in at least one of the first or second parts at a weight percent from greater than zero percent, about 10 percent, about 20 percent, or about 30 percent, to about 40 percent, about 50 percent, or about 60 percent, about 70 percent, or a weight percent between any pair of the foregoing values, based on the total weight of the system part (either Part A or Part B) that the flame retardant component is present in. In some embodiments, Attorney Docket No.: 2023P00345WO_shl the flame retardant (which may be the same or different) may be present in both Part A and Part B. [0050] In some embodiments, the total amount of the flame retardant component in the potting composition is a weight percent from about 15 percent, about 20 percent, about 25 percent, or about 30 percent, to about 40 percent, about 45 percent, about 50 percent, about 55 percent, or about 60 percent, or a weight percent between any pair of the foregoing values, based on the total weight of the potting composition. For example, a first flame retardant component may be present in Part A at a weight percent from about 30 percent, about 35 percent, or about 40 percent, to about 45 percent, about 50 percent, or about 55 percent, or a weight percent between any pair of the foregoing values, based on the total weight of Part A; and a second flame retardant component may be present in Part B at a weight percent from about 20 percent, about 25 percent, or about 30 percent, to about 35 percent, about 40 percent, or about 45 percent, or a weight percent between any pair of the foregoing values, based on the total weight of Part B. [0051] It has been found that in some instances, a suitable amount of flame retardant component in the potting composition will provide suitable levels of flame retardancy without compromising other desirable characteristics. For example, in some instances the stiffness, hardness, flexibility, durability, or structural resilience of certain foam compounds may be unsuitable when high levels of flame retardant is present. In some embodiments, a suitable weight percent of flame retardant component in a polyurethane foam to provide a suitable level of flame retardancy and providing a suitably strong potting compound may be an amount of from about 25 percent, about 30 percent, or about least 35 percent, to about 40 percent, about 45 percent, or about 50 percent based on the total weight of the potting composition. Thermoplastic Spheres [0052] Suitable thermoplastic microspheres for use in any of the systems, kits and methods described herein are described in, for example, U.S. Publication Nos.2021/0214581, 2019/0284438 and 2019/0062028 and U.S. Patent No.10,100,204, the entire contends of each of which is incorporated herein by reference. Suitable thermoplastic microspheres include, but are not limited to, those commercially available from Nouryon under the trade name Expancel^®. Such thermoplastic microspheres encapsulate a gas (a “blowing agent”). As heat is added, the gas expands and the shell of the microsphere softens. Typically, the shell thickness of the microsphere is about 2 microns and the particle size of the microsphere is about 12 microns, Attorney Docket No.: 2023P00345WO_shl which expands to about 40 microns upon heating. Once cooled, the expanded microsphere retains the size encapsulating the blowing agent. [0053] Suitable series of Expancel^® microspheres include, for example, Expancel^® DU, Expancel^® WU, Expancel^® MB, Expancel^® SL, Expancel^® DE(T), Expancel^® WE, and Expancel^® FG. Any combination of any of the foregoing may be used in the present invention. The expansion temperature can be tailored to the specific microspheres used. [0054] Expancel^® microspheres are commercially available either expanded or unexpanded, either in wet or dry forms. Each of these forms (i.e., expanded and/or unexpanded, wet and/or dry, including any combination thereof) can be used in any of the embodiments described herein. [0055] Additional thermoplastic microspheres for use in any of the systems described herein include, but are not limited to, those commercially available from Chase corporation under the tradename Dualite^®. Both unexpanded and expanded microspheres are available commercially in U and E product series, respectively. [0056] Additional thermoplastic microspheres for use in any of the systems described herein include, but are not limited to, those commercially available from Kureha under the tradename Kureha^® microsphere. Such acrylic polymer thermoplastic microspheres encapsulate a hydrocarbon blowing agent. Suitable series of Kureha^® microspheres include, for example, Kureh ^® H750, Kureha^® H850, Kureha^® H880, Kureha^® S2340, Kureha^® S2640, and Kureha^® H1100-S. Any combination of any of the foregoing may be used in the present invention. The expansion temperature can be tailored to the specific microspheres used. The “S” series are suitable for expansion between about 160º C and about 190º C. The “H” series are suitable for expansion between above about 190º C. Hollow Glass Spheres [0057] Suitable hollow glass spheres for use in any of the systems, kits and methods described herein include, but are not limited to, glass bubbles available commercially from 3M under K, S, and iM series, e.g., 3M^™ Glass Bubbles K20. [0058] Hollow glass spheres are typically added to Part A and/or Part B after cooling the mixtures to ensure integrity of the glass spheres remain. Additionally, any physical transformation, e.g., vigorous mixing or exposure to heat may shatter the glass spheres. Attorney Docket No.: 2023P00345WO_shl Curing Agents [0059] In certain embodiments of any of the systems, kits and methods described herein, the one or more curing agents is selected from multifunctional primary amines, secondary amines, tertiary amines, and any combination thereof. [0060] Suitable curing agents for use in any of the systems, kits and methods described herein include, but are not limited to, Jeffamine T 403, Jeffamine D 400 and Jeffamine D 230, available commercially from Huntsman, as well as, e.g., di- and polyamine linkers such as m- xylenediamine (MXDA) available commercially from Mitsubishi Gas Chemical. [0061] Depending on the flash point of the curing agent, they may be added after cooling the mixtures. In the event the curing agent’s flash point is below the Tonset of the thermoplastic microspheres, the curing agent should be added after first expanding the thermoplastic microspheres or the thermoexpansion is conducted under inert atmosphere, e.g., Ar or N₂ gas. [0062] The curing agent is present in the second part (Part B) of the system. The curing agent may be present in Part B at a weight percent from greater than zero percent, about 5 percent, about 10 percent, about 20 percent, or about 30 percent, to about 40 percent, about 50 percent, or about 60 percent, about 70 percent, about 80 percent, or a weight percent between any pair of the foregoing values, based on the total weight of Part B. For example, the curing agent may be present in Part B in about 5 to about 50 % w/w or between about 20 and about 80 % w/w of Part B. Additional Additives [0063] The systems, kits and potting compositions described herein may optionally include additional additives, either as separate components or mixed into one or more of the components described above to form Part A and/or Part B. The optional additional additives may be present in the potting composition at a weight percent from greater than zero, about 0.1 percent, about 0.5 percent, or about one percent, to about five percent, about 10, about 20 percent, or about 30 percent, based on the total weight of the potting composition, or a weight percentage between any pair of the foregoing values. The weight percentage of the optional additional additives may be applied to the combined total of all additional additives present or to each additional additive separately. [0064] Some examples of additional additives that may be added to either or both of the first (Part A) or second (Part B) parts include, but are not limited to, crosslinkers, chain extenders Attorney Docket No.: 2023P00345WO_shl (e.g., trimethylolpropane triacetoacetate), moisture scavengers, thixotropy agents, rheology additives, nucleating agents, surfactants, diluents, anti-settling agents, flame-retardant enhancers, adhesion promoters, and components and any combination thereof. In some embodiments, the optional additional additives include waxes, release agents, antioxidants, reinforcing fillers, pigments, heat stabilizers, UV stabilizers, plasticizers, rheology modifiers, processing aids, lubricants, mold release agents, or component or combinations thereof. Suitable reinforcing fillers include mineral fillers and glass fibers. [0065] In the event the additional additive are thermally non-compatible in the preparation of Part A or Part B in the heating and expanding the thermoplastic microsphere stage, the additional additives should be added after cooling the mixtures. [0066] FIG.1 is a flow chart depicting an exemplary, non-limiting, process for preparing the two-part systems described herein. [0067] Table 1 below shows exemplary, non-limiting, properties of the two-part systems described herein. TABLE 1 Parameter Exemplary Broader Range Exemplary Narrower Range Temperature range of about 50 to about 200 about 80 to about 150 Attorney Docket No.: 2023P00345WO_shl Examples System Components [0068] Trimethylolpropane triacetoacetate is a chain extender, available from EChemi. Epon 862 (diglycidyl ether of bisphenol F) is a low viscosity, liquid epoxy resin manufactured from epichlorohydrin and bisphenol, available from GracoRoberts, Westlake. Epon 828 is a difunctional bisphenol A/epichlorohydrin derived liquid epoxy resin, available from GracoRoberts, Westlake, etc. FR Cros S 10 is a long chain ammonium polyphosphate used as solidflame retardant, available from Budenheim. Antiflame^TM PIBT31 is an organophosphate ester derivate F used as liquid halogen-free flame retardant, available from M Chemical. Expancel 920 DU 40 is a dry powder of unexpanded thermoplastic microspheres that expands at a temperature range of 121-178 °C, with a particle size of around 40 µm in its expanded form, available from Nouyron. Expancel 51 DU 40 is a dry powder of unexpanded thermoplastic microspheres that expands at a temperature range of 105-151 °C, with a particle size is around 40 µm in its expanded form, available from Nouyron. Jeffamine T 403, a polyetheramine, is a trifunctional, primary amine epoxy curing agent with an average molecular weight of about 440, available from Huntsman. Jeffamine D 230 is a difunctional primary amine epoxy curing agent having an average molecular weight of approximately 230, available from Huntsman. Jeffamine D 400 is a difunctional primary amine epoxy curing agent having an average molecular weight of approximately 430, available from Huntsman. RheoBYK 410 is a liquid rheology additive (a solution of a modified urea), available from BYK. A-1110 is a primary amino silane adhesion promoter, available from Momentive. Dynasylan AMMO is an amino silane adhesion promoter, available from Evonik. Silquest^TM A-189 (gamma-mercaptopropyltrimethoxysilane) is an adhesion promoter, available from Momentive. Glass Bubbles K20 are hollow glass microspheres, available from 3M. Safire 400 (melamine poly(zinc phosphate)) is a solid flame retardant, available from Huber Advanced Materials. Araldite DY-31 CH is an epoxy resin diluent, available from Huntsman. MXDA (m-xylylenediamine) is an epoxy curing agent, available from Mitsubishi gas chemical. Heloxy Modifier 107 is the diglycidyl ether of cyclohexane dimethano, useful as a reactive diluent or viscosity reducing modifier for epoxy resin formulations, available from Miller-Stephenson. Attorney Docket No.: 2023P00345WO_shl Initial Compatibility Studies [0069] As an initial screening study, the compatibility of various thermoplastic microspheres (thermoplastic bubbles) with various epoxies, liquid flame retardants, liquid epoxy resin diluents, and amine curing agents (hardeners) was investigated. During this initial screening, the density of the mixture before heating was measured and, upon heating, a decrease in density of compatible mixtures was observed as the blowing agent acts to expand the shell of the thermoplastic microsphere. The density was also monitored at various temperatures in order to optimize the expansion time for each different microsphere. [0070] For example, the expansion of thermoplastic microsphere Expancel 920 DU 40 in combination with Jeffamine T 403 and D 230 (an exemplary Part B formulation) was monitored at various temperatures for 30 mins heating at each specific temperature in FIG.2 and density was measured after cooling the mixture to room temperature before heating at the next elevated temperature. As can be seen from FIG.2, an optimized expansion temperature of between about 120º C and about 140º C was observed for this system. As a follow-up test, the same mixture was prepared and mixture was directly heated to 140 º C for an hour, also reaching the same density as the stepwise temperature screening described above. Thus, the optimized temperature and duration of thermal expansion was determined for this system to be about 120º C to about 140º C for about one hour. [0071] Once an optimized temperature and expansion time was identified for a microsphere / additive combination, the two-part systems (Part A and Part B) described in Examples 1-5 were prepared, as described below. Example 1 [0072] In this example, containing a mixture of thermoplastic microspheres and hollow glass microspheres, thermoplastic microspheres were expanded in a mixture of secondary and tertiary amine curing agents in Part B. [0073] The components of Parts A and B are shown in Table 2 below. Attorney Docket No.: 2023P00345WO_shl TABLE 2 Component Amount (g / 100 g Batch) Part A [0074] Formulation of Part A: The liquid and solid components of Part A (containing no thermoplastic or hollow glass microspheres) were mixed at room temperature (final density of Part A: 1.2 g/mL). [0075] Formulation of Part B: Thermoplastic microspheres were added to a mixture of two compatible curing agents. The mixture was heated to expansion temperature for 1.5 hours, wherein the density dropped as the thermoplastic microspheres expanded. Thereafter, the mixture was allowed to cool and the additional ingredients including glass bubble K20 were added to form Part B (final density of Part B: 0.54 g/mL). [0076] Adhesive Curing: Parts A and B were mixed in a 1:1 ratio. The initial viscosity or the resulting mixture was 1800 mPa.s, which allows the potting compound to be easily poured. Upon curing, the density of the resulting adhesive was 0.73 g/mL, which is lower than common nonfoaming systems. Example 2 [0077] In this example, only thermoplastic microspheres were used in Part B and were expanded in a mixture of a liquid flame retardant and a combination of secondary and tertiary amine curing agents. Attorney Docket No.: 2023P00345WO_shl [0078] The components of Parts A and B are shown in Table 3 below. TABLE 3 Component Amount (g / 100 g Batch) Part A [0079] Formulation of Part A: The liquid and solid components of Part A (containing no thermoplastic or hollow glass microspheres) were mixed at room temperature (final density of Part A: 1.2 g/mL). [0080] Formulation of Part B: Thermoplastic microspheres were added to a mixture of active reagents of Part B and a liquid flame retardant. The mixture was heated to expansion temperature for 1.5 hours wherein the density dropped as the thermoplastic microspheres expanded. Thereafter, the mixture was allowed to cool and the additional ingredients were added to form Part B (final density of Part B: 0.58 g/mL). [0081] Adhesive Curing: Parts A and B were mixed in a 1:1 ratio. The initial viscosity or the resulting mixture was 1900 mPa.s, which allows the potting compound to be easily poured. Upon curing, the density of the resulting adhesive was 0.80 g/mL, which is lower than common nonfoaming systems. Example 3 [0082] In this example, thermoplastic microspheres are used in Part B and expanded in a mixture of a liquid flame retardant and a tertiary amine curing agent. Attorney Docket No.: 2023P00345WO_shl [0083] The components of Parts A and B are shown in Table 4 below. TABLE 4 Component Amount (g / 100 g Batch) Part A [0084] Formulation of Part A: The liquid and solid components of Part A (containing no thermoplastic or hollow glass microspheres) were mixed at room temperature (final density of Part A: 1.2 g/mL). [0085] Formulation of Part B: Thermoplastic microspheres were added to a mixture of active reagents of Part B and a liquid flame retardant. The mixture was heated to expansion temperature for 1.5 hours wherein the density dropped as the thermoplastic microspheres expanded. Thereafter, the mixture was allowed to cool and the additional ingredients were added to form Part B (final density of Part B: 0.72 g/mL). [0086] Adhesive Curing: Parts A and B were mixed in a 1:1.3 ratio. The initial viscosity or the resulting mixture was 800 mPa.s, which allows the potting compound to be easily poured. Upon curing, the density of the resulting adhesive was 0.87 g/mL, which is lower than common nonfoaming systems. Example 4 [0087] In this example, hollow glass microspheres were used to lower the density of Part A and thermoplastic microspheres were expanded in Part B. The thermoplastic microspheres were Attorney Docket No.: 2023P00345WO_shl expanded in a liquid flame retardant and primary amine, MXDA, with flash point in the range of 140º C - 144º C was subsequently added upon cooling as the curing agent. When using MXDA for the thermal expansion process, thermal expansion is performed under inert atmosphere for safety. The amine and thermoplastic microspheres were deemed compatible at room temperature upon analysis of the resulting density. [0088] The components of Parts A and B are shown in Table 5 below. TABLE 5 Component Amount (g / 100 g Batch) Part A [0089] F xed at room temperature (final density of Part A: 0.8 g/mL). [0090] Formulation of Part B: Thermoplastic microspheres were added to a liquid flame retardant in Part B. The mixture was heated to expansion temperature for 1.5 hours wherein the density dropped as the thermoplastic microspheres expanded. Thereafter, the mixture was allowed to cool to laboratory (room) temperature and the additional ingredients were added to form Part B (final density of Part B: 0.88 g/ml). [0091] Adhesive Curing: Parts A and B were mixed in a 1.35:1 ratio. The initial viscosity or the resulting mixture was 500 mPa.s, which allows the potting compound to be easily poured. Upon curing, the density of the resulting adhesive was 0.82 g/mL, which is lower than common nonfoaming systems. Attorney Docket No.: 2023P00345WO_shl Example 5 [0092] In this example, a different thermoplastic microsphere was used in Part B and expanded in a tertiary amine. The secondary amine was added after the thermal expansion due to incompatibility with Expancel 51 DU 40 at elevated temperature. [0093] The components of Parts A and B are shown in Table 6 below. TABLE 6 Component Amount (g / 100 g Batch) Part A [0094] Formulation of Part A: The liquid and solid components of Part A (containing no thermoplastic or hollow glass microspheres) were mixed at room temperature (final density of Part A: 1.2 g/mL). [0095] Formulation of Part B: Thermoplastic microspheres were added to Jeffamine T 403. The mixture was heated to expansion temperature for 2 hours wherein the density dropped as the thermoplastic microspheres expanded. Thereafter, the mixture was allowed to cool to laboratory (room) temperature and the additional ingredients including secondary amine, Jeffamine D 230, were added to form Part B (final density of Part B: 0.66 g/ml). [0096] Adhesive Curing: Parts A and B were mixed in a 0.8:1 ratio. The initial viscosity or the resulting mixture was 400 mPa.s, which allows the potting compound to be easily poured. Upon Attorney Docket No.: 2023P00345WO_shl curing, the density of the resulting adhesive was 0.85 g/mL, which is lower than common nonfoaming systems. [0097] Select physical and mechanical properties for Examples 1-5 are shown in Table 7 below. TABLE 7 Property Example Example Example Example Example 1 2 3 4 5 g [0098] All patents and publications cited herein are incorporated by reference in their entirety.

Claims

Attorney Docket No.: 2023P00345WO_shl WHAT IS CLAIMED IS: 1. A two-part system comprising (A) a first part (Part A) comprising: (i) one or more epoxy resins; (ii) one or more liquid flame-retardants; (iii) optionally, a first plurality of expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives; and (B) a second part (Part B) comprising: (i) one or more curing agents; (ii) one or more liquid flame-retardants; (iii) optionally, a second plurality of expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives; wherein (a) Part A has a density ranging from about 0.75 to about 1.25 g/mL, when measured in accordance with ASTM D1475 at 23^o C, (b) Part B has a density ranging from about 0.50 to about 0.90 g/mL, when measured in accordance with ASTM D1475 at 23^o C, and (c) at least one of Part A and Part B comprises a plurality of expanded thermoplastic microspheres. Attorney Docket No.: 2023P00345WO_shl 2. The two-part system of claim 1, wherein the one or more epoxy resins is selected from aliphatic and aromatic epoxy resins, and any combination thereof. 3. The two-part system of claim 1, wherein the one or more flame retardants is selected from halogen-free flame retardants. 4. The two-part system of claim 1, wherein the one or more curing agents is selected from multifunctional primary, secondary, or tertiary amines, and any combination thereof. 5. The two-part system of claim 1, wherein the one or more additional additives is selected from crosslinkers, chain extenders, moisture scavengers, thixotropy agents, rheology additives, nucleating agents, surfactants, epoxy resin diluents, anti-settling agents, solid flame retardants, flame-retardant enhancers, adhesion promoters, and components, and any combination thereof. 6. A kit comprising: (A) a first part (Part A) comprising: (i) one or more compatible epoxy resins; (ii) one or more compatible liquid flame-retardants; (iii) optionally, a first plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives; wherein (a) if Part A comprises non-expanded thermoplastic microspheres, components listed in (A) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part A, if present, are heated to a temperature at which expansion of the non-expanded thermoplastic microspheres occurs; Attorney Docket No.: 2023P00345WO_shl (b) Part A is then cooled and any components used in Part A that are incompatible with the thermal process of (a), are added; wherein the resulting Part A has a density ranging from about 0.75 to about 1.25 g/mL, when measured in accordance with ASTM D1475 at 23^o C; and (B) a second part (Part B) comprising: (i) one or more compatible curing agents; (ii) one or more compatible liquid flame-retardants; (iii) optionally, a second plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives; wherein (a) if Part B comprises non-expanded thermoplastic microspheres, components listed in (B) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part B, if present, are heated to a temperature at which expansion of the non-expanded thermoplastic microspheres occurs; (b) Part B is then cooled and any components used in Part B that are incompatible with the thermal process of (a) above, are added; wherein the resulting Part B has a density ranging from about 0.50 to about 0.90 g/mL, when measured in accordance with ASTM D1475 at 23^o C, and wherein at least one of Part A and Part B comprises expanded thermoplastic microspheres. 7. A method for preparing a two-part system, the method comprising: (a) preparing a first part (Part A) by mixing: (i) one or more compatible epoxy resins; Attorney Docket No.: 2023P00345WO_shl (ii) one or more compatible liquid flame-retardants; (iii) optionally, a first plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives; (b) if Part A comprises non-expanded thermoplastic microspheres, components listed in (A) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part A, if present, are heated to a temperature in order to expand the first plurality of non-expanded thermoplastic microspheres; (c) cooling the mixture of step (b) and, optionally, adding the remainder of components used in Part A that are incompatible with the thermal process, thereby forming the first part (Part A); wherein the resulting Part A has a density ranging from about 0.75 to about 1.25 g/mL, when measured in accordance with ASTM D1475 at 23^o C; (d) preparing a second part (Part B) by mixing: (i) one or more compatible curing agents; (ii) one or more compatible liquid flame-retardants; (iii) optionally, a second plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives; (e) if Part B comprises non-expanded thermoplastic microspheres, components listed in (B) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part B, if present, are heated to a temperature in order to expand the second plurality of non-expanded thermoplastic microspheres; Attorney Docket No.: 2023P00345WO_shl (f) cooling the mixture of step (e), and, optionally, adding the remainder of components used in Part B that are incompatible with the thermal process, thereby forming the second part (Part B); wherein the resulting Part B has a density ranging from about 0.50 to about 0.90 g/mL, when measured in accordance with ASTM D1475 at 23^o C, and wherein at least one of Part A and Part B comprises a plurality of expanded thermoplastic microspheres. 8. A method for forming a battery module, wherein the battery module comprises an electric cell and a cavity, the method comprising (a) adding the two-part system of claim 1 to the cavity; and (b) curing the two-part system in the cavity. 9. A method for forming a battery module, wherein the battery module comprises an electric cell and a cavity, the method comprising: (a) preparing a first part (Part A) by mixing: (i) one or more compatible epoxy resins; (ii) one or more compatible liquid flame-retardants; (iii) optionally, a first plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives; (b) if Part A comprises non-expanded thermoplastic microspheres, components listed in (A) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part A, if present, are heated to a temperature in order to expand the first plurality of non-expanded thermoplastic microspheres; Attorney Docket No.: 2023P00345WO_shl (c) cooling the mixture of step (b) and, optionally, adding the remainder of components used in Part A that are incompatible with the thermal process, thereby forming the first part (Part A); wherein the resulting Part A has a density ranging from about 0.75 to about 1.25 g/mL, when measured in accordance with ASTM D1475 at 23^o C; (d) preparing a second part (Part B) by mixing: (i) one or more compatible curing agents; (ii) one or more compatible liquid flame-; (iii) optionally, a second plurality of expanded and/or non-expanded thermoplastic microspheres and/or hollow glass microspheres; and (iv) optionally, one or more additional additives; (e) if Part B comprises non-expanded thermoplastic microspheres, components listed in (B) (i) and (ii), in addition to the non-expanded thermoplastic microspheres used in Part B, if present, are heated to a temperature in order to expand the second plurality of non-expanded thermoplastic microspheres; (f) cooling the mixture of step (e) and, optionally, adding the remainder of components used in Part B that are incompatible with the thermal process, thereby forming the second part (Part B); wherein the resulting Part B has a density ranging from about 0.50 to about 0.90 g/mL, when measured in accordance with ASTM D1475 at 23^o C; (g) mixing Part A and Part B in the cavity; (h) curing the mixture of Part A and Part B in the cavity, wherein at least one of Part A and Part B comprises expanded thermoplastic microspheres. Attorney Docket No.: 2023P00345WO_shl 10. A battery module comprising an electric cell and a kit according to claim 6.