Fire retardant woven continuous fiber thermoplastic composites and articles

Abstract

Fire retardant woven continuous fiber thermoplastic composites and articles made from such hybrid composites can be used in EV battery (or more generally, any lithium-ion battery) applications such as battery cell, battery module, battery enclosure / casing to mitigate or minimize the effects of thermal runaway events. Such articles include a battery component for a lithium-ion battery, a thermal barrier component for the battery component, a thermal barrier component between battery cells and an enclosure / casing for the battery pack. The thermal barrier component includes a flame retardant glass fiber reinforced thermoplastic resin with an intumescent flame retardant additive. A flame retardant woven continuous glass fiber fabric thermoplastic composite is over-molded with the flame retardant glass fiber reinforced thermoplastic resin. The resulting thermal barrier component can protect the battery component from thermal damage.

Description

23POLY0047-WO-ORDFIRE RETARDANT WOVEN CONTINUOUS FIBER THERMOPLASTIC COMPOSITES AND ARTICLESTECHNICAL FIELD

[0001] This disclosure relates to a flame retardant composition that includes a polypropylene (PP)-based polymer, to processes of making such a composition and to articles made from such compositions.BACKGROUND

[0002] Batteries, for example, those used in electric vehicles (EVs), can sometimes experience thermal runaway events. A thermal runaway event is one in which an exothermic process triggers other exothermic and / or endothermic processes which collectively result in an uncontrollable increase in temperature. The series of reactions can lead to the destruction of the batteries and, in some instances, to fire and explosion. One technique to mitigate the risk of fire and explosion due to a thermal runaway event is to cover the batteries using battery shells. Another technique is to separate batteries in a battery module using thermal barriers. A further technique is to enclose battery packs with multiple battery modules using thermal barriers. Such shells, barriers and enclosures can be made from flame retardant materials. Such shells, barriers and enclosures can retain the effects of the thermal runaway event within them. By doing so, these components can prevent the high temperatures from being transmitted to adjacent components of the EVs.

[0003] W02020 / 060341 describes a battery case for an electric car. As described in W02020 / 060341, such a battery case includes a support part on which a battery module is stably placed and supported. The support part includes a side wall part formed to extend upward from an edge part of the support part. An inner frame is coupled to the upper surface of the support part and partitions a seating part of the battery module. An outer frame is coupled to the outer side surface of the support part.

[0004] US2016 / 0134231 describes a plastic photovoltaic module frame and rack, and a composition for making the same. The composition includes (A) a thermoplastic polymer, particularly a thermoplastic polyolefin, (B) a reinforcing element, particularly glass fiber, (C) a non-halogen containing, intumescent flame retardant, (D) an impact-modifier, particularly a23POLY0047-WO-ORD polyolefin elastomer, (E) a coupling agent, and, optionally, (F) one or more additives such as an antioxidant, UV-stabilizer, etc.

[0005] US2022 / 006150 describes a battery containment system that includes a thermoplastic polymer, particularly a thermoplastic polyolefin, (B) a reinforcing element, particularly glass fiber, (C) a non-halogen containing, intumescent flame retardant, (D) an impactmodifier, particularly a polyolefin elastomer, (E) a coupling agent, and, optionally, (F) one or more additives such as an antioxidant, UV-stabilizer, etc.SUMMARY

[0006] This disclosure describes technologies relating to fire retardant woven continuous fiber fabric thermoplastic composite laminates and articles made using such compositions.

[0007] This disclosure describes flame retardant woven continuous fiber fabric thermoplastic composite laminates and hybrid articles made from such laminates. Such laminates and hybrid articles can be used in EV battery applications to mitigate or minimize the effects of thermal runaway events. The formulation design described here leverages a synergistic effect of novel intumescent flame retardant (IFR) additives deployed in a thermoplastic resin and woven continuous fiber fabric (WCFF). Polymer matrices such as polypropylene (PP) and others containing IFR additives demonstrate excellent flame retardancy. Such an effect is because the IFR additives, when exposed to high temperature, react to produce a dense and continuous intumescent char layer on the surface to protect the polymer matrices during combustion. A woven continuous glass fiber fabric is an example of WCFF. WCFF is one of the solutions to enhance particle erosion resistance of thermoplastic composite laminates and hybrid articles during particle impingement during a thermal runaway event. As described below, good impregnation of the woven continuous glass fiber fabric can be achieved by selecting optimal flow thermoplastic PP resin and also by adding optimal quantity of the IFR additives.

[0008] The composite laminate described here is a flame retardant woven continuous glass fiber fabric PP thermoplastic composite laminate that can be processed and manufactured by consolidating or laminating single layer or stack of layers (lay-up) of flame retardant woven continuous glass fiber fabric thermoplastic semi-pregs. A semi-preg or semi-finished product described here is a continuous woven glass fiber fabric powder coated with a flame retardant PP23POLY0047-WO-ORD thermoplastic resin. Consolidation or lamination is a process by which a single layer or stack of layers (lay-up) of semi-preg is exposed to heat, cooling, and tonnage / pressure over a defined time using a lamination press to fabricate the composite laminate which is the final product. The flame retardant woven continuous glass fiber fabric PP thermoplastic composite laminate can then be injection over-molded with flame retardant PP thermoplastic resin, e.g., glass fibers of the same, to obtain flame retardant PP thermoplastic composite hybrid article using a molding machine. Good adhesion between the flame retardant woven continuous fiber fabric PP thermoplastic composite laminates and the over-molding flame retardant PP thermoplastic resin can be obtained by efficiently pre-heating the surface of the flame retardant woven continuous fiber fabric PP thermoplastic composite laminate prior to the over-molding. Such adhesion can prevent premature delamination at the interface of the flame retardant PP thermoplastic composite hybrid during a thermal runaway event.

[0009] Implementations of the techniques described here yield a flame retardant PP thermoplastic resin composition with improved flame retardancy. The formulation design of the flame retardant woven continuous fiber fabric PP thermoplastic composite laminates described here leverages a synergistic effect of novel intumescent flame retardant (IFR) additives deployed in a PP -based resin and woven continuous fiber fabric (WCFF). The flame retardant thermoplastic composite hybrid articles described here can be implemented as an alternative to metallic (e.g., aluminum or steel) battery enclosures. They can also be implemented as thermal barrier components. The thermoplastic composite hybrid enclosures offer better flame retardancy compared to such metallic enclosures. They offer a high stiffness-to-weight ratio and better part integration. The over-molding process implemented in this disclosure can reduce or eliminate the use of secondary operations (e.g., pre-treatment) to improve the flame retardancy of metallic battery enclosures such as a coating and paint step. The time and cost to manufacture the thermoplastic composite hybrid components (battery pack enclosures and thermal barrier) described here is less than the cycle time required when using sheet molding compounds (SMCs) with fire retardant additives for battery pack enclosures.

[0010] The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.23POLY0047-WO-ORDDESCRIPTION OF DRAWINGS

[0011] FIGS. 1A-1C are schematic diagrams of different battery assemblies.

[0012] FIGS. 2A-2C are schematic diagrams of a tool arrangement for making a flame retardant thermoplastic composite hybrid article.

[0013] FIGS. 2D-2F are schematic diagrams of another tool arrangement for making another flame retardant thermoplastic composite hybrid article.

[0014] FIGS. 2G-2J are schematic diagrams of another tool arrangement for making another flame retardant thermoplastic composite hybrid article.

[0015] FIGS. 3A-3D are schematic diagrams of another tool arrangement for making a flame retardant PP thermoplastic composite hybrid article.

[0016] FIGS. 3E-3H are schematic diagrams of another tool arrangement for making a flame retardant PP thermoplastic composite hybrid article.

[0017] FIGS. 3I-3N are schematic diagrams of another tool arrangement for making a flame retardant PP thermoplastic composite hybrid article.

[0018] FIG. 4 is a flowchart of an example of a process of enclosing a battery component with a thermal barrier made from the flame retardant composite hybrid article of FIGS. 2A-2C.

[0019] Like reference symbols in the various drawings indicate like elements.DETAILED DESCRIPTION

[0020] FIG. 1A is a schematic diagram of a battery assembly 100. The battery assembly 100 is a battery module that includes battery cells. The battery cells can include, for example, a battery cell 102, which can be a lithium-ion battery, specifically of the type that can power EVs. The battery cell 102 can be of any type, e.g., cylindrical, prismatic, pouch or any combination of them. The battery cell 102 is contained within by a shell 104, which serves as a container for the battery cell 102. For example, the shell 104 is a protective cover that covers an entirety of the battery cells 102. The shell 104 is made from the composition described in this disclosure. For example, the shell 104 is a thermal barrier component such as a thermal runaway and grit impingement shell that can operate as a thermal barrier during a thermal runaway event. In the23POLY0047-WO-ORD context of this disclosure, grit impingement means impact on a surface by a high temperature, high pressure gas, for example, particles and other solid content of an air-fuel mixture flowing at velocities as high as 70 meters per second (m / s). In general, lithium-ion battery thermal runaway releases thermal energy in the form of high temperature gas and flame and high pressure as well as solid contents due to the decomposition of battery materials. A torch and grit test can mimic the thermal impact of thermal runaway using a torch and grit impingement made of aluminum oxide or alumina (AI2O3). In such a test, the thermal exposure consists of greater than 1,100 degrees Centigrade (°C) and grits at velocities as high as 75-150 m / s. By thermal barrier, it is meant that the shell 104 can prevent a significant portion of the heat generated by the thermal runaway and grit impingement event from propagating through the shell 104.

[0021] FIG. IB is a schematic diagram of another battery assembly 120. The battery assembly 120 can be a battery pack that includes multiple battery modules and each battery module (e.g., battery module 122) includes multiple battery cells. For example, the schematic diagram of FIG. IB shows two rows of battery modules. Each row includes five battery modules. In the schematic diagram shown in FIG. IB, the battery pack includes five battery modules (e.g., battery module 122), each with multiple battery cells 102. The battery pack 120 can include additional components to protect the structural integrity of the battery pack 120. An example of such components can include side crash protection thermoplastic resins 123. An example of a thermal barrier enclosure can be used to thermally isolate the battery modules 122 within the battery pack 120 from nearby components. To do so, a thermal barrier enclosure including multiple thermal barrier components (e.g., a top cover 124, a tray 126) can be arranged on different sides (e.g., at the top and at the bottom) of the battery assembly 120. Like the shell 104 described with reference to FIG. 1 A, the thermal barrier enclosure including the multiple thermal barrier components is a thermal barrier component such as a thermal runaway and grit impingement enclosure that can operate as a thermal barrier during a thermal runaway event. In this manner, the thermal barrier enclosure can thermally isolate an entirety of the battery assembly 120 from other components adjacent to the battery assembly 120. In some implementations, the thermal barrier component can be a separator that separates battery modules 122 within each row and further separates battery modules between rows. In some implementations, the thermal barrier component can be a battery enclosure or casing such as the top cover 124 and the bottom tray 126.23POLY0047-WO-ORD

[0022] FIG. 1C is a schematic diagram of another battery assembly 130. The example battery assembly 130 includes two battery modules 132a and 132b similar to the battery module 122 in FIG. IB. The schematic diagram shown in FIG. 1C represents a mini-battery assembly. Each battery module includes multiple battery cells 102. The battery modules 132a and 132b are spaced apart from each other. The battery modules 132a, 132b are each supported by a battery tray 134. The battery tray 134 can have an integrated cooling channel. The battery assembly 130 can include a battery cover 136 that covers the top of the battery modules 132a and 132b. The battery cover 136 can thermally isolate one surface of the battery assembly 130, e.g., the top surface of each battery module 132a and 132b, from adjacent components. Additionally, the battery cover 136 can be formed to thermally isolate battery modules 132a and 132b from each other by a barrier 138. For example, the barrier 138 is attached to a bottom surface of the battery cover 136 and extends away from the bottom surface. The barrier 138 includes a thickness sufficient to separate the two battery modules 132a and 132b such that a thermal runaway event in one battery does not affect the other. Each component in the battery assembly 130, i.e., the battery tray 134, the battery cover 136 and the barrier 138, is a thermal barrier component such as a thermal runaway and grit impingement enclosure that can operate as a thermal barrier during a thermal runaway event. Each thermal barrier component can be deployed in the space separating the battery modules from each other. In addition, each battery cell 102 in the battery module 132a and 132b can be covered by the shell 104 as described with reference to FIG. 1A. For example, the shell 104 can cover each battery module. In addition, the barrier 138 can be positioned between one or more battery modules. By doing so, the barrier component 138 can separate each battery module from other battery modules or a group of battery modules from other groups of battery modules.

[0023] The shell 104 is an over-molded structure, which includes a flame retardant glass fiber reinforced PP thermoplastic resin 108. The resin, which includes an intumescent flame retardant (TFR) additive, is included in a component that is a part of the shell 104. A flame retardant woven continuous glass fiber fabric PP thermoplastic composite (composite 110) is over-molded with the resin 108. The composite 110 can also contain a PP resin with a composition that is similar to the resin used for resin 108. The combination of the resin 108 and the composite 110 results in a PP thermoplastic composite hybrid article, which can protect the battery component from damage in response to the thermal runaway event or grit impingement on the battery component. As shown23POLY0047-WO-ORD schematically in FIG. 1A, the resin 108 is over-molded as a layer onto the composite 110. When the battery module / pack assembly 100 is constructed, the resin 108 is positioned between the composite 110 and the battery cell 102 such that heat generated by the thermal runaway event is incident directly on the resin 108 and indirectly on the composite 110. In alternative constructions, the composite 110 can be positioned between the resin 108 and the battery cell 102.

[0024] The shell 104 shown schematically in FIG. lA is an example of a protective cover for a battery cell of an EV vehicle. The shell 104 described in this disclosure can be applied to other battery components such as battery module, battery top cover and battery tray, each of which is susceptible to thermal damage from the thermal runaway event and grit impingement. In some examples, the shell 104 can be implemented as a thermal blanket, which serves as a thermal barrier layer between battery modules, between battery modules and an enclosure casing and / or between battery cells within the battery module.

[0025] The resin 108 is a PP matrix made from a composition that includes a PP -based polymer, a flame retardant composition, additive (including IFR additives) and glass fibers. The amount of the PP -based polymer is 10 to 50 weight percentage (wt%) with respect to the total composition, for example, 20 to 30 wt%, 25 to 35 wt%. The PP can be a PP homopolymer or a PP copolymer, either including random copolymers, (multi)block copolymers or any combination of them.

[0026] In implementations in which the PP copolymer is a random copolymer, the propylene copolymer can include at least 70 wt% of PP monomer units and up to 30 wt% of ethylene and / or a-olefin monomer units based on the total weight of the propylene copolymer. The a-olefin is selected from the group of a-olefins having 4-10 carbon atoms, e.g., 1-butene, 1- pentene, 4-methyl-l -pentene, 1 -hexene, 1 -heptene or 1 -octene. The propylene copolymer can be a propylene-ethylene copolymer.

[0027] The amount of ethylene and / or a-olefin monomer units in the propylene copolymer can be 1-15 wt%, e.g., 1-10 wt%, 1-6 wt%, 1-4 wt% based on the total weight of the propylene copolymer. When the polypropylene-based polymer includes a propylene a-olefin copolymer, the propylene copolymer can be a propylene-ethylene random copolymer in which the amount of23POLY0047-WO-ORD ethylene monomer units is 1-15 wt%, e.g., 1-10 wt%, more preferably 1-6 wt%, more preferably 1-4 wt% based on the total weight of the propylene copolymer.

[0028] The melt flow index (MFI) of the propylene homopolymer or propylene copolymer can be, e.g., at least 10 decigrams per minute (dg / min), at least 20 dg / min, at least 30 dg / min, or at least 40 dg / min and / or at most 200 dg / min, at most 150 dg / min, at most 100 dg / min, or at most 50 dg / min measured according to ISO1133-1 :2011 (2.16 kg / ° °C).

[0029] In some implementations, the PP polymer matrix can include heterophasic propylene copolymer that includes a propylene homopolymer and / or a propylene copolymer consisting of at least 90 wt% of propylene monomer units and at most 10 wt% of ethylene and / or a-olefin monomer units, based on the total weight of the propylene-based matrix. The heterophasic propylene copolymer can also include a dispersed ethyl ene-a-olefin copolymer. The sum of the total amount of propylene-based matrix and total amount of the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer is 100 wt%.

[0030] Heterophasic propylene copolymers (also known as impact propylene copolymers or propylene block copolymers) are beneficial due to their attractive combination of mechanical properties, such as impact strength over a wide temperature range and their low cost. Heterophasic propylene copolymers are generally prepared in one or more reactors, by polymerization of propylene in the presence of a catalyst and subsequent polymerization of an ethylene-a-olefin mixture. The resulting polymeric materials are heterophasic, but the specific morphology usually depends on the preparation method and monomer ratios used. The heterophasic propylene copolymers employed in the present disclosure can be produced, for example, by multistage process polymerization, such as bulk polymerization, gas phase polymerization, slurry polymerization, solution polymerization or any combinations thereof. Any conventional catalyst systems, for example, Ziegler-Natta or metallocene may be used.

[0031] The heterophasic propylene copolymer may be prepared by a process that includes polymerizing propylene and optionally ethylene and / or a-olefin in the presence of a catalyst system to obtain the propylene-based matrix, and subsequently polymerizing ethylene and a-olefin in the propylene-based matrix in the presence of a catalyst system to obtain the dispersed ethylene-23POLY0047-WO-ORD a-olefin copolymer. These steps can be performed in different reactors. The catalyst systems for the first step and for the second step may be different or same.

[0032] The heterophasic propylene copolymer of the composition described here consists of a propylene-based matrix and a dispersed ethylene-a-olefin copolymer. The propylene-based matrix typically forms the continuous phase in the heterophasic propylene copolymer. The amounts of the propylene-based matrix and the dispersed ethylene-a- olefin copolymer may be determined by 13C-NMR.

[0033] In some implementations, the propylene-based matrix consists of a propylene homopolymer and / or a propylene copolymer consisting of at least 90 wt% of propylene monomer units and at most 10 wt% of comonomer units selected from ethylene monomer units and a-olefin monomer units having 4 to 10 carbon atoms, e.g., consisting of at least 95 wt% of propylene monomer units and at most 5 wt% of the comonomer units, based on the total weight of the propylene-based matrix. The comonomer in the propylene copolymer of the propylene-based matrix is selected from the group of ethylene, 1 -butene, 1 -pentene, 4-methyl-l -pentene, 1 -hexene, 1 -heptene and 1 -octene. For example, the comonomer can be ethylene.

[0034] In some implementations, the propylene-based matrix consists of a propylene homopolymer. The fact that the propylene-based matrix consists of a propylene homopolymer is advantageous in that a higher stiffness is obtained compared to the case where the propylene-based matrix is a propylene-a-olefin copolymer.

[0035] The MFI of the propylene-based matrix (before the heterophasic propylene copolymer is mixed into the composition of the invention), MFIPP, can be, e.g., at least 0.1 dg / min, at least 0.2 dg / min, at least 0.3 dg / min, at least 0.5 dg / min, and / or for example at most 20 dg / min, at most 10 dg / min, at most 5.0 dg / min, at most 3.0 dg / min, at most 1.0 dg / min, measured according to ISO1133-l:2011 (2.16 kg / 230 °C).

[0036] The propylene-based matrix can be present in an amount of 60 to 98 wt%, e.g., at most 97 wt%, at most 96 wt%, at most 95 wt%, at most 93 wt% or at most 91 wt%, based on the total heterophasic propylene copolymer. For example, the propylene-based matrix is present in an amount of at least 70 wt%, more preferably at least 75 wt%, e.g., at least 80 wt%, at least 85 wt%, at least 87 wt% or at least 90 wt%, based on the total heterophasic propylene copolymer.23POLY0047-WO-ORD

[0037] In some implementations, the propylene-based matrix is semi-crystalline, i.e., neither 100% amorphous nor 100% crystalline. For example, the propylene-based matrix is at least 40% crystalline, e.g., at least 50%, at least 60% crystalline and / or at most 80% crystalline, e.g., at most 70% crystalline. For example, the propylene-based matrix has a crystallinity of 60 to 70%. In the context of this disclosure, the degree of crystallinity of the propylene-based matrix is measured using differential scanning calorimetry (DSC) according to ISO11357-1 and ISO11357- 3 of 1997, using a scan rate of 10 °C / min, a sample of 5 milligrams (mg) and the second heating curve using as a theoretical standard for a 100% crystalline material 207.1 Joules per gram (J / g).

[0038] Besides the propylene-based matrix, the heterophasic propylene copolymer also includes a dispersed ethylene-a-olefin copolymer. The dispersed ethylene-a-olefin copolymer is also referred to herein as the ‘dispersed phase’. The dispersed phase is embedded in the heterophasic propylene copolymer in a discontinuous form. The particle size of the dispersed phase is typically in the range of 0.05 to 2.0 microns, as may be determined by transmission electron microscopy (TEM). The amount of the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer may herein be sometimes referred as RC. For example, the amount of ethylene monomer units in the ethylene-a-olefin copolymer is 5 to 65 wt%, e.g., at least 10 wt%, at least 20 wt%, at least 30 wt%, at least 40 wt% or at least 45 wt% and / or at most 60 wt%, at most 58 wt%, at most 55 wt% or at most 50 wt%. The amount of ethylene monomer units in the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer may herein be sometimes referred as RCC2.

[0039] The a-olefin in the ethylene-a-olefin copolymer can be chosen from the group of a-olefins having 3 to 8 carbon atoms. Examples of suitable a-olefins having 3 to 8 carbon atoms include but are not limited to propylene, 1 -butene, 1 -pentene, 4-methyl-l -pentene, 1 -hexene, 1- heptene and 1-octene. For example, the a-olefin in the ethylene-a-olefin copolymer is chosen from the group of a-olefins having 3 to 4 carbon atoms and any mixture thereof. In another example, the a-olefin is propylene, in which case the ethylene-a-olefin copolymer is ethylene-propylene copolymer.

[0040] The MFI of the dispersed ethylene a-olefin copolymer (before the heterophasic propylene copolymer is mixed into the composition of the invention), MFIrubber, may be for23POLYOQ47-WO-ORD example at least 0.001 dg / min, at least 0.03 dg / min or at least 0.05 dg / min, and / or for example at most 0.1 dg / min or 0.01 dg / min. MFI™^ is calculated according to Equation 1.

[0041] In Equation 1, “MFIheterophasic” is the MFI (dg / min) of the heterophasic propylene copolymer measured according to ISO1133-1 :2011 (2.16 kg / 230 °C), “MFImatrix” is the MFI (dg / min) of the propylene-based matrix measured according to ISO1133-1 :2011 (2.16 kg / 230 °C), “matrix content” is the fraction of the propylene-based matrix in the heterophasic propylene copolymer, and “rubber content” is the fraction of the dispersed ethylene-a-olefin copolymer in the heterophasic propylene copolymer. The sum of the “matrix content” and the “rubber content” is 1. In Equation 1, “Log” in the formula means logio.

[0042] In some examples, the dispersed ethylene-a-olefin copolymer is present in an amount of 2.0 to 40 wt%, e.g., at least 3.0 wt%, at least 4.0 wt%, at least 5.0 wt%, at least 7.0 wt% or at least 9.0 wt%, based on the total heterophasic propylene copolymer. For example, the dispersed ethylene-a-olefin copolymer is present in an amount of at most 30 wt%, more preferably at most 25 wt%, e.g., at most 20 wt%, at most 15 wt%, at most 13 wt% or at most 10 wt%, based on the total heterophasic propylene copolymer. In the heterophasic propylene copolymer in the composition disclosed here, the sum of the total weight of the propylene-based matrix and the total weight of the dispersed ethylene-a-olefin copolymer is 100 wt% of the heterophasic propylene copolymer.

[0043] For example, the heterophasic propylene copolymer has a fraction soluble in p- xylene at 25 °C (CXS) measured according to ISO 16152:2005 of 2.0 to 40 wt%, for example 9.0 to 25 wt%. In another example, the amount of ethylene monomer units in the heterophasic propylene copolymer (sometimes referred as TC2) is in the range of 0.5 to 5.0 wt%, for example 1.0 to 3.0 wt%, based on the heterophasic propylene copolymer. The amount of ethylene monomer units in the heterophasic propylene copolymer (sometimes referred as TC2) is in the range of 0.5 to 5.0 wt%, for example 1.0 to 3.0 wt%, based on the heterophasic propylene copolymer.

[0044] In some examples of the heterophasic propylene copolymer described here, the comonomer in the propylene-a-olefin copolymer is selected from ethylene and the group of a-23POLY0047-WO-ORD olefins having 4 to 10 carbon atoms and the a-olefin in the ethylene-a-olefin copolymer is selected from the group of a-olefins having 3 to 8 carbon atoms. Most preferably, in the heterophasic propylene copolymer according to the invention, the comonomer in the propylene-a-olefin copolymer is ethylene and the a-olefin in the ethylene-a-olefin copolymer is propylene.

[0045] The values of the MFI of the propylene-based matrix ^‘MFImatrix”) and the MFI of the dispersed ethylene-a-olefin elastomer (“MFIrubber”) mentioned herein are understood as the values before the heterophasic propylene copolymer is mixed with other components to obtain the composition described here. The value of the MFI of the heterophasic propylene copolymer FM ihelerophasic") refers to the final MFI of the heterophasic propylene copolymer. For example, in case the heterophasic propylene copolymer is not subjected to vis-breaking or shifting by melt-mixing with a peroxide, the “MFIheterophasic” is the original MFI value of the heterophasic propylene copolymer. In case the heterophasic propylene copolymer is subjected to vis-breaking or shifting by melt-mixing with a peroxide, the “MFIheterophasic” is the value of the heterophasic propylene copolymer after such vis-breaking or shifting.

[0046] In some implementations, the composition described here includes one type of heterophasic propylene copolymer, while in others the propylene-based polymer is or includes a mixture of heterophasic propylene copolymers having different MFI. In some examples, the heterophasic propylene copolymer in the composition according to the invention may have a melt flow index as measured according to ISO1133-1 :2011 (2.16 kg / 230 °C) of 0.1 to 100 dg / min.

[0047] The MFI of some examples of heterophasic propylene copolymers can be at least 5 dg / min, at least 10 dg / min or at least 15 dg / min and / or at most 50 dg / min, at most 40 dg / min, at most 30 dg / min or at most 25 dg / min, measured according to ISO1133-1 : 2011 (2.16 kg / 230 °C). The amount of the dispersed ethylene-a-olefin copolymer is 10 to 50 wt%, preferably 30 to 40 wt%, based on the heterophasic propylene copolymer and preferably the amount of ethylene in the ethylene- a-olefin copolymer is 40 to 60 wt% based on the ethylene-a-olefin copolymer. In some implementations, the propylene-based polymer consists of such heterophasic propylene copolymer.

[0048] The MFI of some examples of heterophasic propylene copolymers be at least 0.1 dg / min, at least 0.2 dg / min, at least 0.3 dg / min, at least 0.5 dg / min, at least 1.0 dg / min, at least 1.523POLY0047-WO-ORD dg / min or at least 2.0 and / or, for example, at most 10 dg / min, at most 8 dg / min or at most 5 dg / min, measured according to ISO1133-1 :2011 (2.16 kg / 230 °C). The amount of the dispersed ethylene- a-olefin copolymer is 10 to 50 wt%, preferably 21 to 30 wt%, based on the heterophasic propylene copolymer and preferably the amount of ethylene in the ethylene- a-olefin copolymer is 40 to 60 wt% based on the ethylene-a-olefin copolymer.

[0049] The MFI of some examples of heterophasic propylene copolymers can be at least 5 dg / min or at least 10 dg / min and / or at most 40 dg / min, at most 30 dg / min, at most 25 dg / min or at most 20 dg / min, measured according to ISO1133-1 :2011 (2.16 kg / 230 °C). The amount of the dispersed ethylene-a-olefin copolymer is 10 to 50 wt%, preferably 10 to 20 wt%, based on the heterophasic propylene copolymer and preferably the amount of ethylene in the ethylene- a-olefin copolymer is 40 to 60 wt% based on the ethylene-a-olefin copolymer.

[0050] The MFI of some examples of heterophasic propylene copolymers can be at least 20 dg / min, at least 25 dg / min, at least 30 dg / min or at least 35 dg / min and / or, for example, at most 100 dg / min, at most 80 dg / min, at most 60 dg / min or at most 50 dg / min, measured according to ISO1133-1 :2011 (2.16 kg / 230 °C). Preferably, the amount of the dispersed ethylene-a-olefin copolymer is 10 to 50 wt%, preferably 15 to 25 wt%, based on the heterophasic propylene copolymer and preferably the amount of ethylene in the ethylene- a-olefin copolymer is 50 to 70 wt% based on the ethylene-a-olefin copolymer.

[0051] In some implementations, the propylene-based polymer is a mixture of heterophasic propylene copolymers. The mixture includes a heterophasic propylene copolymer having an MFI measured according to ISO1133-1 :2011 (2.16 kg / 230 °C) of at least 0.1 dg / min, at least 0.2 dg / min, at least 0.3 dg / min, at least 0.5 dg / min, at least 1.0 dg / min, at least 1.5 dg / min or at least 2.0 and / or, for example, at most 10 dg / min, at most 8 dg / min or at most 5 dg / min. The amount of the dispersed ethylene-a-olefin copolymer is 10 to 50 wt%, preferably 21 to 30 wt%, based on the heterophasic propylene copolymer. The amount of ethylene in the ethylene- a-olefin copolymer is 40 to 60 wt% based on the ethylene-a-olefin copolymer and a heterophasic propylene copolymer having an MFI measured according to ISO1133-1 :2011 (2.16 kg / 230 °C) of at least 5 dg / min or at least 10 dg / min and / or at most 40 dg / min, at most 30 dg / min, at most 25 dg / min or at most 20 dg / min. The amount of the dispersed ethylene-a-olefin copolymer is 10 to 50 wt%,23POLY0047-WO-ORD preferably 10 to 20 wt%, based on the heterophasic propylene copolymer. The amount of ethylene in the ethylene- a-olefin copolymer is 40 to 60 wt% based on the ethylene-a-olefin copolymer. The mixture can further include a heterophasic propylene copolymer having an MFI measured according to ISO1133-1 :2011 (2.16 kg / 230 °C) of at least 20 dg / min, at least 25 dg / min, at least 30 dg / min or at least 35 dg / min and / or, for example, at most 100 dg / min, at most 80 dg / min, at most 60 dg / min or at most 50 dg / min. The amount of the dispersed ethylene-a-olefin copolymer is 10 to 50 wt%, preferably 15 to 25 wt%, based on the heterophasic propylene copolymer. The amount of ethylene in the ethylene- a-olefin copolymer is 50 to 70 wt% based on the ethylene-a- olefin copolymer.

[0052] As described above, the resin 108 is a PP matrix made from a composition that includes the PP -based polymer (described above), a flame retardant composition, additive (including IFR additive) and glass fibers. The flame retardant composition may be a halogen-free flame retardant composition or a halogenated flame retardant composition. In some implementations, the amount of the flame retardant with respect to the total composition is 1.0 to 40 wt%, e.g., 3.0 to 30 wt%, 5.0 to 25 wt%, 10 to 20 wt%.

[0053] The halogen-free flame retardant composition can include an organophosphorus compound. The organophosphorus compound is selected from the group consisting of melamine phosphate, melamine polyphosphate, melamine pyrophosphate, piperazine phosphate, piperazine polyphosphate, piperazine pyrophosphate, 2-methylpiperazine monophosphate, tricresyl phosphate, alkyl phosphates, tetraphenyl pyrophosphate, poly(2-hydroxy propylene spirocyclic pentaerythritol bisphosphate) and poly(2,2-dimethylpropylene spirocyclic pentaerythritol bisphosphonate) and combinations thereof. Alternatively, or in addition, the organophosphorus compound is selected from the group consisting of melamine phosphate, melamine polyphosphate, melamine pyrophosphate, piperazine phosphate, piperazine polyphosphate, piperazine pyrophosphate and 2-methylpiperazine monophosphate and combinations thereof.

[0054] In some examples, the organophosphorus compound includes a first compound selected from melamine phosphate, melamine polyphosphate and melamine pyrophosphate, and a second compound selected from piperazine phosphate, piperazine polyphosphate, piperazine23POLY0047-WO-ORD pyrophosphate and 2-methylpiperazine monophosphate. The weight ratio between the first compound and the second compound can be, e.g., 1 :5 to 5: 1, 1 :5 to 1 : 1 or 1 : 1 to 5:1.

[0055] In some examples, the halogen-free flame retardant composition can include zinc oxide and / or ammonium polyphosphate. The amount of zinc oxide in the halogen-free flame retardant composition with respect to the total amount of the organophosphorus compound, zinc oxide and ammonium polyphosphate is 1.0 to 10 wt%.

[0056] In some examples, the halogen-free flame retardant composition can include ammonium polyphosphate. The amount of ammonium polyphosphate in the halogen-free flame retardant composition with respect to the total amount of the organophosphorus compound, zinc oxide and ammonium polyphosphate is 5.0 to 15 wt%.

[0057] In some examples, the halogen-free flame retardant composition includes particles that include a first compound selected from melamine phosphate, melamine polyphosphate and melamine pyrophosphate, a second compound selected from piperazine phosphate, piperazine polyphosphate, piperazine pyrophosphate and 2-methylpiperazine monophosphate, zinc oxide and ammonium polyphosphate. The amount of the first compound, e.g., melamine phosphate, is 50 to 80 wt%, the amount of the second compound, e.g., piperazine phosphate, is 10 to 25 wt%, the amount of zinc oxide is 1.0 to 10 wt%, and the amount of the ammonium polyphosphate is 5.0 to 15 wt%, each measured with respect to the particles. The amount of particles with respect to the total composition is 15 to 40 wt%.

[0058] In some examples, the halogen-free flame retardant composition includes an aromatic phosphate ester, the amount of which is 0.1 to 15 wt% with respect to the total composition. The aromatic phosphate ester is selected from the group consisting of resorcinol bis(diphenyl phosphate); tetraphenyl resorcinol bis(diphenylphosphate); bisphenol A bi s(diphenyl phosphate); bisphenol A diphosphate; resorcinol bis(di-2,6-xylyl phosphate), phosphoric acid, mixed esters with [1,1 '-biphenyl]-4-4'-diol and phenol; phosphoric trichloride, polymer with 1,3- benzenediol and phenylester; l,3-phenylene-tetrakis(2,6-dimethylphenyl)diphosphate; isopropenylphenyl diphenyl phosphate; 4-phenylphenolformaldehyde phenylphosphonate; tris(2,6-xylyl) phosphate; resorcinol bis(di-2,6-xylyl phosphate); bisphenol S bis(diphenyl phosphate); resorcinol -bisphenol A phenyl phosphates.23POLY0047-WO-ORD

[0059] In implementations in which the IFR is a halogenated flame retardant composition, such composition can include a brominated flame retardant. Suitable examples include tetrabromobisphenol A derivatives, including bis(2-hydroxyethyl)ether of tetrabromobisphenol A, bis(3-acryloyloxy-2- hydroxypropyl)ether of tetrabromobisphenol A, bis(3 -methacryloyloxy -2- hydroxypropyl)ether of tetrabromobisphenol A, bis(3-hydroxypropyl)ether of tetrabromobisphenol A, bis(2,3-dibromopropyl)ether of tetrabromobisphenol A, diallyl ether of tetrabromobisphenol A, and bis(vinylbenzyl)ether of tetrabromobisphenol A; brominated polycarbonates, tetrabromobisphenol A polycarbonate oligomer, brominated polyacrylate such as polypentabromobenzyl acrylate; brominated polystyrenes, such as polydibromostyrenes and polytribromostyrenes; brominated BPA polyepoxides, tetrabromocyclooctanes; dibromoethyldibromocyclohexanes such as 1 ,2-dibromo-4-(l ,2-dibromoethyl)-cyclohexane; ethylene-bis-tetrabromophthalimide; hexabromocyclododecanes; tetrabromophthalic anhydrides; brominated diphenylethers such as decabromodiphenyl ether; poly(2,6-dibromophenylene ether); tris(2,4,6- tribromophenoxy- 1 ,3,5-triazine; tris(tribromoneopentyl)phosphate; and decabromodiphenyl ethane. Particularly preferred examples include bis(2,3- dibromopropyl)ether of tetrabromobisphenol A (commercially available as FR-720 from ICL Industrial Products) and polypentabromobenzyl acrylate (commercially available as FR-1025 from ICL Industrial Products), tris(tribromoneopentyl)phosphate (commercially available as FR-370 from ICL Industrial Products), decabromodiphenyl ether (commercially available as FR-1210 from ICL Industrial Products) and decabromodiphenyl ethane (commercially available as FR-1410 from ICL Industrial Products).

[0060] Again, as described above, the resin 108 is a PP matrix made from a composition that includes the PP -based polymer (described above), the flame retardant composition, additive (including IFR additives) and glass fibers. The additives can include nucleating agents, stabilizers, e.g., heat stabilizers, anti-oxidants, UV stabilizers; colorants, like pigments and dyes; clarifiers; surface tension modifiers; lubricants; flame-retardants; mould-release agents; flow improving agents; plasticizers; anti-static agents; blowing agents.

[0061] The glass fibers can include flat glass fibers.23POLY0047-WO-ORD

[0062] The amount of the additives can depend on their type and function and typically is of from 0 to about 10 wt%. The amount of the additives can be, e.g., from about 0.1 to about 5 wt%; from about 1 to about 4 wt% or from 1.5 to about 3 wt% based on the total composition. The total amount of the components adds up to 100% by weight.

[0063] The resin 108 can be made by melt-mixing its components, namely, the PP-based polymer (described above), the flame retardant composition, the additives (including IFR additive) and the glass fibers. The resin 108 can be made in a form that allows easy processing into a shaped article in a subsequent step, like in pellet or granular form. The resin 108 can be a mixture of different particles or pellets, like a blend of the heterophasic propylene copolymer and a masterbatch of additives. In some implementations, the resin 108 is in pellet or granular form as obtained by mixing all components in an apparatus like an extruder; the advantage being a composition with homogeneous and well-defined concentrations of the additives. In melt-mixing, the flame retardant composition, the additive and the glass fibers are mixed with the PP-based polymer at a temperature that exceeds the melting point of the PP-based polymer. Melt-mixing can be implemented in an extruder in a temperature ranging from between 170 °C and 300 °C.

[0064] In some implementations, the composite 110 is formed as laminates that include the IFR additive. The composite is formed by consolidating or laminating single layer and or stack of layers (lay-up) of flame retardant woven continuous fiber fabric PP thermoplastic semi-pregs. A semi-preg or semi-finished product is a woven continuous glass fiber fabric powder coated with a flame retardant PP thermoplastic resin. Consolidation or lamination is a process by which a semi- preg is exposed to heat, cooling, and tonnage / pressure over a defined time using a lamination press to fabricate the composite laminate, which is the final product.

[0065] FIGS. 2A-2C are schematic diagrams of a tool arrangement for making a flame retardant PP thermoplastic composite hybrid article. As described below, the hybrid article produced using the tool arrangement described with reference to FIGS. 2A-2C includes a composite laminate over-molded with a resin layer. The tool arrangement includes a first plate 202 and a second plate 204 that defines a tool cavity 207 (FIG. 2C). One surface of the first plate 202 includes a projected portion 203 that projects outwardly from an end portion 205 such that the projected portion 203 and end portion 205 abut at a shoulder 213. The projected portion 20323POLY0047-WO-ORD defines the tool core. One surface of the second plate 204 includes a recessed portion 209 that projects inwardly from an end portion 211 such that the recessed portion 209 and the end portion 211 abut at a shoulder 215. The recessed portion 209 defines the tool cavity 207 in the second plate 204. The first plate 202 and the second plate 204, including the tool cavity 207 (i.e., the portion defined by the recessed portion 209), are constructed and arranged to form the tool arrangement. Specifically, when the end portion 205 of the first plate 202 is placed in contact with the end portion 211 of the second plate 204, then the projected portion 203 projects into the recessed portion 209. The two plates, the projected portion 203 and the recessed portion 209 are dimensioned such that the tool cavity 207 (i.e., an open space) is defined between the projected portion 203 and the recessed portion 209 when the end portion 205 is in contact with the end portion 211.

[0066] In the schematic shown in FIG. 2A, the tool arrangement is in an open position. In this open position, the composite 110 formed as a laminate is placed within the tool cavity 207 of the second plate 204. Vacuum is applied through the suction ports to hold the composite 110 / laminate in place within the tool cavity 207. The composite 110 includes a cut 275 (e.g., an opening) to inject the resin 108 to the other side of the core using a filling point or drop 208. The second plate 204 includes multiple suction ports (e.g., suction port 217) through which vacuum can be drawn. In FIGS. 2A-2C, a solid illustration (filled with black) of the suction port indicates that suction has been applied and a clear illustration (no fill) of the suction port indicates that no suction has been applied.

[0067] The two plates are then brought into contact with each other such that the end portions 205 and 211 touch each other to define the tool cavity 207. The second plate 204 has an opening or filling point or drop 208 through which material can be injected into the tool cavity 207. In the schematic shown in FIG. 2B, the tool arrangement is transitioned to a closed position by bringing the first plate 202 in contact with the second plate 204. Vacuum continues to be drawn through the suction ports. The composite 110 is over-molded with an over-molding resin 108. The over-molding resin used here includes a flame retardant long fiber PP thermoplastic resin or a flame retardant short glass fiber PP thermoplastic resin. As filler / reinforcement, woven continuous fiber fabric including glass, carbon fiber or a combination of them can be used. As resin, commodity resins such as PP and engineering resins such as polyamide, polyester can be used.23POLY0047-WO-ORD

[0068] To do so, the over-molding resin 108 can be injected through the opening 208 into the tool cavity 207. In some implementations, before over-molding the composite 110 with the over-molding resin 108, the surface of the composite 110 can be pre-heated to a temperature that optimizes adhesion between the composite 110 and the over-molding resin 108 by means of an infrared heater. The pre-heating temperature depends on the thickness of the composite 110 and can range from 70 °C to 140 °C. Pre-heating to achieve good adhesion avoids premature delamination at the interface of the composite 110 and the resin 108. The molding conditions including the mold and melt temperature, the cooling temperature, the inj ection speed and the cycle time are optimized for good adhesion.

[0069] In the schematic shown in FIG. 2C, the tool arrangement is transitioned to an open position. Vacuum is no longer drawn through the suction ports. The output of the operations described with reference to FIG. 2B is a flame retardant PP thermoplastic composite hybrid article 210 that has the properties to resist thermal damage at high temperature and can be deployed as a battery module enclosure and or a thermal barrier component to a lithium-ion battery such as the battery pack 102 (FIG. 1).

[0070] FIGS. 2D-2F are schematic diagrams of another tool arrangement for making another flame retardant thermoplastic composite hybrid article. As described below, the hybrid article produced using the tool arrangement described with reference to FIGS. 2D-2F includes two composite laminates over-molded with a resin layer between the two composite laminates. The tool arrangement in FIGS. 2D-2F is substantially identical to that in FIGS. 2A-2C. The tool arrangement includes the first plate 202 and the second plate 204, which, when positioned in contact with each other, define the tool core 207.

[0071] In the schematic shown in FIG. 2D, the tool arrangement is in an open position. In this open position, a first composite 110 formed as a laminate is placed within the tool cavity 207 of the second plate 204. Vacuum is applied through the suction ports (e.g., the suction port 217) to hold the composite laminate 110 in place within the tool cavity 207. A second composite 212 formed as a laminate is placed on the projected portion 203 of the first plate 202. Vacuum is applied through the suction ports (e.g., the suction port 219) to hold the laminate in place within the tool core 203.23POLY0047-WO-ORD

[0072] The two plates are then brought into contact with each other such that the end portions 205 and 211 touch each other to define the tool cavity 207. The second plate 204 has the opening 208 through which material can be injected into the tool cavity 207. In the schematic shown in FIG. 2E, the tool arrangement is transitioned to a closed position by bringing the first plate 202 in contact with the second plate 204. Vacuum continues to be drawn through the suction ports defined in the first plate 202 and the second plate 204. The first composite 110 and the second composite 212 are over-molded with the over-molding resin 108 substantially identical to the one used in the arrangement described above with reference to FIGS. 2A-2C. To do so, the overmolding resin 108 can be injected through the opening 208 into the tool cavity 207. In some implementations, before over-molding the composite 110 and 212 with the over-molding resin 108, the surface of the composite 110 and composite 212 can be pre-heated to a temperature that optimizes adhesion between the composite 110, the composite 212 and the over-molding resin 108 by means of an infrared heater. The pre-heating temperature depends on the thickness of the composite 110 and can range from 70 °C to 140 °C. Pre-heating to achieve good adhesion avoids premature delamination at the interface of the composite 110 and the resin 108. The molding conditions including the mold and melt temperature, the cooling temperature, the injection speed and the cycle time are optimized for good adhesion.

[0073] In the schematic shown in FIG. 2F, the tool arrangement is transitioned to an opened position. Vacuum is no longer drawn through the suction ports. The output of the operations described with reference to FIG. 2E is a flame retardant thermoplastic composite hybrid 214 that has the properties to resist thermal damage at high temperature and can be deployed as a battery module enclosure and or a thermal barrier component to a lithium-ion battery such as the battery pack 102 (FIG. 1).

[0074] FIGS. 2G-2J are schematic diagrams of another tool arrangement for making another flame retardant thermoplastic composite hybrid article. As described below, the hybrid article produced using the tool arrangement described with reference to FIGS. 2G-2J includes a composite laminate over-molded with two layers of the resin 108, each on either side of the composite laminate 110. The tool arrangement in FIGS. 2G-2J is substantially identical to that in FIGS. 2A-2C and FIGS. 2D-2F with a few modifications as described below. The tool arrangement23POLY0047-WO-ORD includes the first plate 202. The tool arrangement also includes the second plate 204, which, when positioned in contact with each other, define the tool cavity 207.

[0075] In the schematic shown in FIG. 2G, the tool arrangement is in an open position. In this open position, the composite 110 formed as a laminate is placed within the tool cavity 207 of the second plate 204. Vacuum is applied through the suction ports (e.g., the suction port 221) to hold the laminate in place within the tool cavity 207. The two plates are then brought into contact with each other such that the end portions 205 and 211 touch each other to define the tool cavity 207. The second plate 204 has an opening 208 through which material can be injected into the tool cavity 207.

[0076] FIG. 2H describes injection over-molding of the first layer of the resin 108 on the other side or core’s side of the composite 110. The injection over-molding of this first layer can be called the first shot or IK injection over-molding.

[0077] FIG. 21 is a schematic diagram showing injection over-molding of a second layer of the resin 108. The injection over-molding of this second layer is termed as a second shot or 2K injection over-molding. During this second step, the tool opens partially using a precision opening with a compression ring to give an appropriate gap for the 2K shot as well as keeping the tool shutoffs for 2K shot of the resin 108. In some implementations, before over-molding the composite 110 with the over-molding resin 108, the surface of the composite 110 can be pre-heated by means of an infrared heater to a temperature that optimizes adhesion between the composite 110 and the over-molding resin 108. The pre-heating temperature depends on the thickness of the composite 110 and can range from 70 °C to 140 °C. Pre-heating to achieve good adhesion avoids premature delamination at the interface of the composite 110 and the resin 108. The molding conditions including the mold and melt temperature, the cooling temperature, the injection speed and the cycle time are optimized for good adhesion..

[0078] In the schematic shown in FIG. 2J, the tool arrangement is transitioned to an open position. The output of the operations described with reference to FIG. 2H and 21 is a flame retardant thermoplastic composite hybrid 230 that has the properties to resist thermal damage at high temperature and can be deployed as a battery module enclosure and or a thermal barrier component to a lithium-ion battery such as the battery pack 102 (FIG. 1).23POLY0047-WO-ORD

[0079] FIGS. 3A-3D are schematic diagrams of a tool arrangement for making a flame retardant PP thermoplastic composite hybrid article. As described below, the hybrid article produced using the tool arrangement described with reference to FIGS. 3A-3D includes a onesided foamed structure of flame retardant thermoplastic composite hybrid article (Composite 110 injection over-molded with a layer of foamed resin 108). The tool arrangement in FIGS. 3A-3D is substantially identical to that in FIGS. 2A-2C.

[0080] In the schematic shown in FIG. 3 A, the tool arrangement is in an open position. In this open position, the composite 110 formed as a laminate is placed within the tool cavity 307 of the second plate 304. Vacuum is applied through the suction ports to hold the laminate in place within the tool cavity 307. The second plate 304 includes multiple suction ports (e.g., suction port 317) through which vacuum can be drawn. In FIGS. 3 A-3C, a solid illustration (filled with black) of the suction port indicates that suction has been applied and a clear illustration (no fill) of the suction port indicates that no suction has been applied. The two plates are then brought into contact with each other such that the end portions 305 and 311 touch each other to define the tool cavity 307. The second plate 304 has an opening 308 through which material can be injected into the tool cavity 307.

[0081] In the schematic shown in FIG. 3B, the tool arrangement is transitioned to a closed position by bringing the first plate 302 in contact with the second plate 304. Vacuum continues to be drawn through the suction ports. The composite 110 is over-molded with an over-molding resin 108. The over-molding resin used here includes a flame retardant long fiber PP thermoplastic resin. To do so, the over-molding resin 108 can be injected through the opening 308 into the tool cavity 307.

[0082] In the schematic shown in FIG. 3C, the tool arrangement is partially opened for core - back foaming of the resin 108. Partially opening the tool arrangement means separating the first plate 302 and the second plate 304 to allow the core - back foaming of the resin 108. During the core - back foaming, a foaming agent, e.g., a physical blowing agent (such as nitrogen or other inert gas) or chemical blowing agent is introduced into the melt of the resin 108 during the injection over-molding process. Doing so results in a first skin 381 of the resin 108 and a second skin 383 of the resin 108.23POLY0047-WO-ORD

[0083] In some implementations, before over-molding the composite 110 with the overmolding resin 108, the surface of the composite 110 can be pre-heated by means of infrared heater to a temperature that optimizes adhesion between the composite 110 and the over-molding resin 108. The pre-heating temperature depends on the thickness of the composite 110 and can range from 70 °C to 140 °C. Pre-heating to achieve good adhesion avoids premature delamination at the interface of the composite 110 and the resin 108. The molding conditions including the mold and melt temperature, the cooling temperature, the injection speed and the cycle time are optimized for good adhesion.

[0084] In the schematic shown in FIG. 3D, the tool arrangement is transitioned to an open position. Vacuum is no longer drawn through the suction ports. The output of the operations described with reference to FIG. 3B is a one-sided foamed structure of flame retardant thermoplastic composite hybrid article 310 that has the properties to resist thermal damage at high temperature and can be deployed as a battery module enclosure and or a thermal barrier component to a lithium-ion battery such as the battery pack 102 (FIG. 1).

[0085] FIGS. 3E-3H are schematic diagrams of another tool arrangement for making another flame retardant thermoplastic composite hybrid article. As described below, the hybrid article produced using the tool arrangement described with reference to FIGS. 3E-3H includes two-sided foamed structure or foamed sandwich structure of flame retardant thermoplastic composite hybrid article (foamed resin 108 sandwiched between two layers of composite). The tool arrangement in FIGS. 3E-3H is substantially identical to that in FIGS. 3A-3D with the modifications described below. The tool arrangement includes the first plate 302 and the second plate 304, which, when positioned in contact with each other, define the tool core 307.

[0086] In the schematic shown in FIG. 3E, the tool arrangement is in an open position. In this open position, a first composite 110 formed as a laminate is placed within the tool cavity 307 of the second plate 304. Vacuum is applied through the suction ports (e.g., the suction port 317) to hold the laminate in place within the tool cavity 307. A second composite 312 formed as a laminate is placed on the projected portion (tool’s core) 303 of the first plate 302. Vacuum is applied through the suction ports (e.g., the suction port 319) to hold the laminate in place within the tool cavity 307. The two plates are then brought into contact with each other such that the end portions 30523POLY0047-WO-ORD and 311 touch each other to define the tool cavity 307. The second plate 304 has the opening 308 through which material can be injected into the tool cavity 307.

[0087] In the schematic shown in FIG. 3F, the tool arrangement is transitioned to a closed position by bringing the first plate 302 in contact with the second plate 304. Vacuum continues to be drawn through the suction ports defined in the first plate 302 and the second plate 304. The first composite 110 and the second composite 312 are over-molded with the over-molding resin 108 substantially identical to the one used in the arrangement described above with reference to FIGS. 3A-3D. To do so, the over-molding resin 108 can be injected through the opening 308 into the tool cavity 307.

[0088] In the schematic shown in FIG. 3G, the tool arrangement is partially opened for core - back foaming of the resin 108. Partially opening the tool arrangement means separating the first plate 302 and the second plate 304 to allow the core - back foaming of the resin 108. During the core-back foaming, a foaming agent, e.g., a physical blowing agent (such as nitrogen or other inert gas) or chemical blowing agent is introduced into the melt of the resin 108 during the injection over-molding process. Doing so results in a first skin 381 of resin 108 and a second skin 383 of resin 108.

[0089] In some implementations, before over-molding the composite 110 and 212 with the over-molding resin 108, the surface of the composite 110 and composite 212 can be pre-heated by means of an infrared heater to a temperature that optimizes adhesion between the composite 110 / composite 212 and the over-molding resin 108. The pre-heating temperature depends on the thickness of the composite 110 and can range from 70 °C to 140 °C. Pre-heating to achieve good adhesion avoids premature delamination at the interface of the composite 110 / composite 212 and the resin 108. The molding conditions including the mold and melt temperature, the cooling temperature, the injection speed and the cycle time are optimized for good adhesion.

[0090] In the schematic shown in FIG. 3H, the tool arrangement is transitioned to an opened position. Vacuum is no longer drawn through the suction ports. The output of the operations described with reference to FIG. 3H is a two-sided foamed structure or foamed sandwich structure of flame retarding thermoplastic hybrid article 314 that has the properties to resist thermal damage23POLY0047-WO-ORD at high temperature and can be deployed as a battery module enclosure and or a thermal barrier component to a lithium-ion battery such as the battery pack 102 (FIG. 1).

[0091] FIGS. 3I-3N are schematic diagrams of another tool arrangement for making another flame retardant thermoplastic composite hybrid article. As described below, the hybrid article produced using the tool arrangement described with reference to FIGS. 3I-3K includes two- sided foamed structure or foamed sandwich structure of flame retardant thermoplastic composite hybrid article (composite 110 sandwiched between two layers of foamed resin 108). The tool arrangement in FIGS. 3I-3N is substantially identical to that in FIGS. 3A-3D and FIGS. 3E-3H with a few modifications as described below. The tool arrangement includes a first plate 302. The tool arrangement also includes the second plate 304, which, when positioned in contact with each other, define the tool cavity 307.

[0092] FIG. 31 describes injection over-molding of the first layer of the resin 108 on the other side or core’s side of the composite 110. The injection over-molding of this first layer can be called the first shot or IK injection over-molding. In the schematic shown in FIG. 31, the tool arrangement is in an open position. In this open position, the composite 110 formed as a laminate is placed within the tool cavity 307 of the second plate 304. Vacuum is applied through the suction ports (e.g., the suction port 321) to hold the laminate in place within the tool cavity 307. The two plates are then brought into contact with each other such that the end portions 305 and 311 touch each other to define the tool cavity 307. The second plate 304 has an opening 308 through which material can be injected into the tool cavity 307.

[0093] In the schematic shown in FIG. 3J, the tool arrangement is transitioned to a closed position by bringing the first plate 302 in contact with the second plate 304. The resin 108 is injected through the opening 308 to one side of the composite 110. Vacuum is applied through the suction ports to hold the composite 110 in place within the tool cavity 307.

[0094] FIG. 3K is a schematic diagram showing injection over-molding of a second layer of the resin 108. The injection over-molding of this second layer is termed as a second shot or 2K injection over-molding. During this second step, the tool opens partially using a precision opening with a compression ring to give an appropriate gap for the 2K shot as well as keeping the tool shutoffs for 2K shot of the resin 108. In the schematic shown in FIG. 3K, the tool arrangement is23POLY0047-WO-ORD partially opened for core - back foaming of the resin 108 that has been injected to one side of the composite 110. Partially opening the tool arrangement means separating the first plate 302 and the second plate 304 to allow the core-back foaming of the first layer or IK of Resin 108. During the core-back foaming process, a foaming agent, e.g., a physical blowing agent (such as nitrogen or other inert gas) or chemical blowing agent is introduced into the melt of the resin 108 during the injection over-molding process. Doing so results in a 1stskin 381 of resin 108 and a second skin 383 of resin 108, both on the core’s side of the composite 110 in which the resin layer 108 has been injected.

[0095] In the schematic shown in FIG. 3L, the tool arrangement is further partially opened to allow appropriate gap to inject a 2ndlayer or the 2K of resin 108 on the other side (cavity’s side) of the composite 110. When doing so, vacuum can be stopped in the suction ports.

[0096] In the schematic shown in FIG. 3M, the tool arrangement remains partially opened for core - back foaming of the second layer or 2K of resin 108 that has been injected to the other side (cavity’s side) of the composite 110. During the core-back foaming, a foaming agent, e.g., a physical blowing agent (such as nitrogen or other inert gas) or chemical blowing agent is introduced into the melt of the resin 108 that has been injected onto the other side (cavity’s side) of the composite 110. Doing so results in a third skin 385 of resin 108 and a fourth skin 387 of resin 108, both on the side (cavity’s side) of the composite 110 in which the second resin layer 108 has been injected.

[0097] The over-molding resin used here includes a flame retardant long fiber thermoplastic resin. In some implementations, before over-molding the composite 110 with the over-molding resin 108, the surface of the composite 110 can be pre-heated by means of an infrared heater to a temperature that optimizes adhesion between the composite 110 and the over-molding resin 108. The pre-heating temperature depends on the thickness of the composite 110 and can range from 70 °C to 140 °C. Pre-heating to achieve good adhesion avoids premature delamination at the interface of the composite 110 and the resin 108. The molding conditions including the mold and melt temperature, the cooling temperature, the injection speed and the cycle time are optimized for good adhesion.23POLY0047-WO-ORD

[0098] In the schematic shown in FIG. 3N, the tool arrangement is transitioned to an open position. The output of the operations described with reference to FIG. 3N is two-sided foamed structure or foamed sandwich structure of flame retardant thermoplastic composite hybrid article 330 (composite 110 sandwiched between two layers of foamed resin 108), that has the properties to resist thermal damage at high temperature and can be deployed as a battery module enclosure and or a thermal barrier component to a lithium-ion battery such as the battery pack 102 (FIG. 1).

[0099] FIG. 4 is a flowchart of an example of a process 400 of protecting a battery component with a flame retardant composite hybrid article made as described above with reference to FIGS. 2A-2C, FIGS. 2D-2F, FIGS. 2G-2J, FIGS. 3A-3D, FIGS. 3E-3H and FIGS. 3L3N. The battery component can include a battery cell or multiple battery cells arranged and constructed as a battery pack or a battery module.

[0100] At 402, a thermal barrier component is made. To do so, at 404, an IFR additive is added to a glass fiber reinforced PP thermoplastic resin to form a flame retardant glass fiber reinforced PP thermoplastic resin (e.g., the resin 108). At 406, a surface of a flame retardant woven continuous glass fiber fabric PP thermoplastic composite laminate (e.g., the composite 110) is preheated by means of an infrared heater to a temperature to optimize adhesion. The temperature to which the surface of the composite is pre-heated is proportional to a thickness of the composite. For example, as the thickness of the composite increases, the temperature to which the composite is pre-heated also increases. In some examples, the temperature can range between 70 °C and 140°C.

[0101] At 408, the composite 110 is over-molded with the resin 108 resulting in the formation of the thermal barrier component. The resin is formed from a polypropylene matrix. The matrix includes the IFR additive. The polypropylene matrix can be made from a propylene homopolymer or a propylene copolymer. The homopolymer or the copolymer can include random copolymers or (multi)block copolymers. The homopolymer or the copolymer can include combinations of the two. When heated, the IFR additive can produce a dense and continuous intumescent char layer on a surface of the polypropylene matrix. The heat can be generated, for example, by thermal events external or internal to the lithium-ion battery.23POLY0047-WO-ORD

[0102] The IFR additive can include a halogen-free flame retardant composition. Alternatively, the IFR additive can include a halogenated flame retardant composition. The composition of the IFR additive can be between 1.0 and 40 wt %. The flame retardant woven continuous glass fiber fabric thermoplastic composite can be formed as laminates. The laminates can include the IFR additive. The flame retardant glass fiber reinforced thermoplastic resin may for example comprise between 1.0 and 40 wt % of the intumescent flame retardant (IFR) additive, with regard to the total weight of the flame retardant glass fiber reinforced thermoplastic resin.

[0103] In some implementations, a single composite 110, formed as a laminate, is overmolded with the flame retardant glass fiber reinforced thermoplastic resin 108 to form a hybrid article. An example of forming such a hybrid article is described with reference to FIGS. 2A-2C. In some implementations, a second composite, formed as a laminate, is over-molded with the flame retardant glass fiber reinforced thermoplastic resin at the same time that a first composite is overmolded with the flame retardant glass fiber reinforced thermoplastic resin. An example of forming such a hybrid composite is described with reference to FIGS. 2D-2F.

[0104] A hybrid composite can be formed as a solid structure with no foaming of the flame retardant glass fiber reinforced thermoplastic during the over-molding process. Alternatively, a hybrid composite can be formed as a foamed structure by introducing a foaming agent in the melt of the flame retardant glass fiber reinforced thermoplastic during the over-molding process. The foaming can be introduced via a physical agent. Nitrogen is an example of such a physical agent. Alternatively, the foaming can be introduced via a chemical blowing agent, e.g., HYDROCEROL HK-40-E™ manufactured by Avient Corporation headquartered in Avon Lake, Ohio, U.S.A.

[0105] The battery component can include a single battery cell. Alternatively, or in addition, the battery component can include a battery module or battery pack including multiple battery cells. The multiple battery cells can be arranged in a specific formation.

[0106] At 410, a battery component for a lithium-ion battery is protected with the thermal barrier component formed at 402. To do so, the thermal barrier component can cover the battery component. Alternatively, the thermal barrier component can thermally isolate different components of the battery component. For example, as described above, the battery component can be a battery module that includes multiple battery cells or a battery pack with multiple battery23POLY0047-WO-ORD modules. To protect the battery component, the thermal barrier component can be deployed to isolate one battery cell from other battery cells. Alternatively, or in addition, the thermal barrier component can be deployed to isolate a subset of battery cells from other battery cells. In some implementations, the thermal barrier component can be implemented to separate all the battery cells from other components in the battery component.

[0107] In some implementations, at 412, the resin 108 is positioned between the battery component and the composite 110 for improved resistance to the thermal runaway event and grit impingement. In some implementations, the hybrid composite can be formed as a sandwich structure. For example, a first sandwich structure can include three layers in which the resin 108 is positioned between two composites 110. In another example, a second sandwich structure can include three layers in which the composite 110 is positioned between two resin layers 108. Other variations with more sandwich structures in which more than one resin layer is positioned between two composite layers or more than one composite layer is positioned between two resin layers or variations of them are also possible.

[0108] Examples

[0109] Three woven continuous glass fiber fabric thermoplastic composite laminate specimens of different thicknesses - 2 mm, 3 mm, 4 mm. These specimens are flame retardant woven continuous glass fiber fabric thermoplastic composite laminates manufactured using 400 and 600 grams per square meter (gsm) woven continuous E-glass fiber fabric (WCGFF). Other samples of the flame retardant glass fiber reinforced thermoplastic resins alone (without the composite) with a thickness of 2, 3 and 4 mm were made. These samples are SABIC commercial grades of flame retardant short (SABIC® PPc H1030) and long (STAMAX™ 30YH570 and STAMAX™ 30YH515) glass fiber reinforced polypropylene resins. Other samples of the woven continuous glass fiber thermoplastic composite laminate (without the IFR additive) with a thickness of 2, 3 and 4 mm were also made using 400 and 600 grams per square meter (gsm) woven continuous E-glass fiber fabric (WCGFF). All samples were subjected to a grit-flame burner at a temperature of between 1,100 and 1,200 °C and heat flux above 200 kiloWatt per square meter (kW / m2) flowed on the sample at high speed of approximately 75 m / s that impinged AI2O3 grit to mimic the abusive thermal environment in a lithium-ion battery thermal runaway.23POLY0047-WO-ORD

[0110] The sample of the flame retardant glass fiber reinforced thermoplastic resins alone without the composite showed a bum-through time of 45-62 seconds. The 2 mm thick sample of composite without the IFR additive showed a bum-through time of about 90 seconds. The 2 mm thick sample of the flame retardant thermoplastic composite laminate showed a significantly longer burn through time of greater than 5 minutes. Burn through performance increased with increasing thickness. The 4 mm thick sample of the flame retardant thermoplastic composite laminate did not show any burn through after 25 minutes of testing.

[0111] Two thermoplastic composite hybrid specimens of about 3.19 and 3.12 mm thick. These are flame retardant thermoplastic composite hybrids containing about 1 mm thick of flame retardant woven continuous glass fiber fabric thermoplastic composite laminate (composite 110) and about 2.19 -2.12 mm thick of flame retardant glass fiber reinforced thermoplastic resin (resin 108). All samples were subjected to UL battery thermal runaway (UL2596) test which simulates realistic thermal runaway conditions (high temperature, grit impingement and pressure of 2.5 bar). During the test, the composite side of the composite hybrid sample was placed in two different positions including directly and indirectly facing the source of the grit-flame and pressure.

[0112] Results indicated that the composite hybrid with the composite facing indirectly the grit-flame and the pressure did not yield at pressures as high as 2.5 bar (250 kiloPascals (kPa)) with the peak recorded pressure of 1,381 kPa. Further, no delamination was observed after the testing indicating good bonding between the two materials as a result of optimized injection overmolding conditions. Results also indicated that the sample with the composite 110 facing directly the source of the grit-flame and pressure yielded with the peak recorded pressure of 344 kPa.

[0113] A number of implementations of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure.

Claims

1. 23POLY0047-WO-ORDCLAIMS1. An article comprising: a lithium-ion battery cell; and a shell configured to be a thermal barrier for the battery cell, the shell comprising: a flame retardant glass fiber reinforced thermoplastic resin comprising an intumescent flame retardant (IFR) additive, and a flame retardant woven continuous glass fiber fabric thermoplastic composite laminate over-molded with the flame retardant glass fiber reinforced thermoplastic resin, and the shell configured to protect the battery cell from thermal damage.

2. The article of claim 1, wherein the flame retardant glass fiber reinforced thermoplastic resin comprises a polypropylene matrix.

3. The article of claim 2, wherein the polypropylene matrix comprises the IFR additive.

4. The article of any one of claims 1-3, wherein the polypropylene matrix is made from a propylene homopolymer or a propylene copolymer, either comprising random copolymers or (multi)block copolymers or any combination thereof.

5. The article of any one of claims 1-4, wherein the IFR additive is configured to produce a dense and continuous intumescent char layer on the surface of the polypropylene matrix in response to heat generated by thermal events external or internal to the lithium-ion battery.23POLY0047-WO-ORD6. The article of any one of claims 1-5, wherein the IFR additive comprises a halogen- free flame retardant composition or a halogenated flame retardant composition.

7. The article of any one of claims 1-6, wherein the IFR additive comprises a weight percentage (wt%) between 1.0 and 40.

8. The article of any one of claims 1-7, wherein flame retardant woven continuous glass fiber fabric thermoplastic composite is formed as laminate that comprise the IFR additive.

9. The article of any one of claims 1-8, wherein the shell comprises one or more layers.

10. The article of any one of claims 1-9, wherein the battery cell is configured to be included in a battery module or battery pack comprising a plurality of battery cells or as one or more thermal barriers between the plurality of battery cells.

11. The article of any one of claims 1-10, wherein the thermal barrier component thermally isolates one battery cell of the plurality of battery cells from other battery cells of the plurality of battery cells or isolates a subset of the plurality of battery cells from other battery cells of the plurality of battery cells.

12. The article of any one of claims 1-11, wherein the flame retardant woven continuous glass fiber fabric thermoplastic is a first composite, wherein the article comprises a second flame retardant woven continuous glass fiber fabric thermoplastic composite over-molded with the flame retardant glass fiber reinforced thermoplastic resin.23POLY0047-WO-ORD13. The article of any one of claims 1-12, wherein the first composite and the second flame retardant woven continuous glass fiber fabric thermoplastic composite are overmolded with the flame retardant glass fiber reinforced thermoplastic resin such that the resin resides between the first composite and the second flame retardant woven continuous glass fiber fabric thermoplastic composite.

14. The article of any one of claims 1-13, wherein the flame retardant woven continuous glass fiber fabric thermoplastic composite over-molded with the flame retardant glass fiber reinforced thermoplastic resin is formed as a solid structure without foam.

15. A method of making a battery component for a lithium-ion battery, the method comprising: forming a thermal barrier component by: adding an intumescent flame retardant (IFR) additive to a glass fiber reinforced thermoplastic resin to form a flame retardant glass fiber reinforced thermoplastic resin, and over-molding a flame retardant woven continuous glass fiber fabric thermoplastic composite with the flame retardant glass fiber reinforced thermoplastic resin; and protecting a battery component for a lithium-ion battery with the thermal barrier component.

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