WO2022141035A1

WO2022141035A1 - Thermal insulation for battery modules

Info

Publication number: WO2022141035A1
Application number: PCT/CN2020/140713
Authority: WO
Inventors: Lu Zou; Xuesi YAO; Yi Guo; Xiangyang Tai; Kainan ZHANG; Debo HONG
Original assignee: Dow Silicones Corporation; Dow Global Technologies Llc
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2022-07-07
Also published as: WO2022143619A1

Abstract

This disclosure relates to a process for thermally insulating adjacent battery cells, typically lithium-ion battery cells, with a self-levelling, non-syntactic silicone foam composition, a battery module having thermally insulated adjacent battery cells obtained or obtainable by the aforementioned process and the use of said composition in the thermally insulation of adjacent battery cells in a battery module and the uses of said battery modules.

Description

[Title established by the ISA under Rule 37.2] THERMAL INSULATION FOR BATTERY MODULES

Rechargeable batteries such as lithium-ion batteries (also referred to as Li-ion batteries or LIBs) are increasingly being used in modules and/or packs of modules for a variety of applications such as electric-vehicle batteries (EVBs) in electric and hybrid (electric and petrol/diesel) powered vehicles with a view to reducing and ultimately eliminating green-house gas emissions therefrom. EVBs are battery packs used to power the propulsion system of electric and hybrid vehicles and as such are designed to give power over sustained periods of time, as opposed to starting, lighting and ignition (SLI) batteries. Lithium-ion batteries are increasingly becoming the preferred option. For the avoidance of doubt in this disclosure and in consideration of usable space from a practical perspective, individual battery cells (sometimes referred to herein as cells) are aligned in battery modules and a battery pack is constituted by a plurality of electrically interconnected battery modules.

The three main constituents in a lithium-ion battery are:

an anode (negative electrode) ;

a cathode (positive electrode) and

an electrolyte.

In use in a lithium-ion battery, lithium ions move from the anode through said electrolyte to the cathode during discharge, and in the reverse direction when being charged.

A wide variety of materials may be used as the anode in a lithium-ion battery but by far the most commercially popular is graphite. Currently the preferred material for the cathode in a lithium-ion battery is selected from one of three materials:

(i) a layered oxide (such as lithium cobalt oxide) ,

(ii) a polyanion (such as lithium iron phosphate) or

(iii) a spinel (such as lithium manganese oxide) .

Lithium-ion batteries, unlike rechargeable batteries with water-based electrolytes, have a potentially hazardous pressurised flammable liquid electrolyte, and require strict quality control during manufacture. A large variety of non-aqueous materials have been proposed and/or used as the electrolyte in a lithium-ion battery. One example of a suitable electrolyte is a mixture of organic carbonates e.g. ethylene carbonate and/or diethyl carbonate containing sources of lithium ions, for example lithium hexafluorophosphate (LiPF ₆) , lithium hexafluoroarsenate monohydrate (LiAsF ₆) , lithium perchlorate (LiClO ₄) , lithium tetrafluoroborate (LiBF ₄) , and lithium triflate (LiCF ₃SO ₃) .

In order to provide power over sustained periods of time, i.e. to enable acceptably long journeys between recharges, EVBs are generally provided in battery packs which are fitted in suitable spaces within the vehicle such as in the car boot or luggage compartment. Irrespective of the position of the pack the housing must protect the occupants of the vehicle from the lithium-ion batteries in case of a malfunction.

When a lithium-ion battery cell malfunctions (for whatever reason) the cell typically overheats and/or becomes over charged which may consequently lead to a fire and/or explosion. Such malfunctions might be caused, for the sake of example, by short circuiting, by being physically damaged i.e. being crushed, or by being subjected to a higher electrical load without having overcharge protection. If present in a multi-cell battery module of lithium-ion batteries, the overheating of a first cell is likely to propagate similar occurrences in adjacent cells resulting in multiple cells in a battery module overheating and failing potentially leading to a “thermal runaway” and cell rupture.

A thermal runaway is usually initiated by the malfunction of one of the battery cells in a battery module leading to that cell releasing heat abnormally and to a sudden increase in the battery cell’s temperature. Once the temperature exceeds a threshold of e.g. about 150℃ or thereabouts, the constituents in the malfunctioning cell initiate a self-heating, autocatalytic, thermal decomposition exothermic reaction, where the temperature of the battery increases rapidly, e.g. at a rate of more than 20℃. per minute, with the temperature of the battery potentially reaching 500℃ or even 1000℃. In the absence of good insulation and heat dissipation structures in the battery module in which the malfunctioning battery is housed, the thermal energy released consequently heats up neighboring battery cells. resulting in a “thermal runaway” within the battery module. When thermal runaway has commenced inside the battery module it cannot be controlled effectively, potentially resulting in combustive exothermic reactions followed by the release of large amounts of flammable electrolyte gas and battery material decomposition gas (e.g. CO ₂, CO, and H ₂) and possible explosions.

Circuitry has been developed to disconnect lithium-ion cells (and battery modules) if/when the voltage generated is outside a predefined safe voltage range per cell. or when overcharged or discharged. However, lithium battery packs, are still susceptible to the aforementioned thermal runaway and cell rupture situations in the event of damage or malfunction.

Hence, the provision of safety measures to enable occupants to exit a vehicle in the event of such a malfunction and to protect them from an immediate risk of toxic gases entering the passenger compartment e.g. by the provision of a sturdy battery pack which can withstand a certain amount of pressure increase because of gas generation and to minimize the effect of the potential for thermal runaway propagation between adjacent cells Thermal insulation materials are now utilized to minimize EV battery thermal runaway propagation. These materials need to have high levels of flame retardancy, high levels of thermal insulation and to have good temperature resistance. They are also preferred to be light weight, have good electrical insulation performance are required in this application. Few polymer composites have been proven to provide such properties especially when dealing with temperatures reaching 500℃ or even 1000℃. One factor that has hindered the finding of suitable means of providing such materials is that lithium-ion battery cells, are typically produced in three forms as cylindrical cells, as “prismatic” cells which are of a rectangular cuboidal shape and as pouch cells. Providing suitable insulation materials, given the above requirements has proven difficult, particularly for battery modules of cylindrical cells because of the irregular geometry of the voids between adjacent cylindrical battery cells.

The use of coated aerogel felt materials between adjacent battery cells in a battery module to slow down heat transfer has been proposed specifically for battery modules of prismatic cells and pouch cells. However, said coated aerogel felt materials cause amorphous aerogel silica to disperse into the working environment, requiring more protective equipment during cutting, packaging, storing and transporting processes. Furthermore, whilst these materials provide good initial thermal insulation performance, performance deteriorates dramatically because of a significant decrease in thickness occurring as the pressure within the battery module increases.

For cylindrical battery cells, the use of silicone rubber syntactic foams has been proposed with a view to trying to fill the irregular voids between cylindrical battery cells in a battery module and provide a physical barrier. For the avoidance of doubt, silicone rubber syntactic foams are silicone rubber foams filled hollow spheres, usually made from glass, which are often referred to as microballoons or cenospheres. However, the use of said silicone rubber syntactic foams especially for filling irregular voids between cylindrical battery cells in a battery module can itself be problematic because of the presence of the glass spheres which typically render the foams before cure of a sufficiently high viscosity not to be self-levelling. Given their relatively fragile nature, glass spheres are furthermore, easy to break during pre-cure mixing and handling, can easily be suspended on the surface resulting non-homogeneity, potentially requiring additional mixing. Furthermore, such foams are expensive because of the use of glass spheres which is contrary to the needs of the industry and such materials are likely not to meet the requirement of UL 94 V type flame retardant tests.

There is provided herein a process for thermally insulating adjacent battery cells in a battery module comprising the steps of :

(1) Taking a battery module comprising a housing with a lid in which is disposed a plurality of battery cells which are electrically connected but otherwise physically separated from each other;

(2) Dispensing a self-levelling, non-syntactic silicone foam composition into said housing, said self-levelling, non-syntactic silicone foam composition comprising the following components:

(i) one or more polydiorganosiloxanes having a viscosity of from 100 to 20,000 mPa. s at 25℃ and at least two unsaturated groups per molecule selected from alkenyl and/or alkynyl groups;

(ii) a platinum group metal, or a compound or complex of a platinum group metal;

(iii) a chemical blowing agent, a physical blowing agent or a mixture of a chemical blowing agent and a physical blowing agent;

(iv) one or more fire retardant fillers; and

(v) a cross-linker comprising an organosilicon compound having at least two, alternatively at least three silicon bonded hydrogen groups per molecule;

(3) Allowing the self-levelling, non-syntactic silicone foam composition to flow within the housing and self-level and as such fill voids between adjacent battery cells in said battery module; and

(4) enabling the self-levelling, non-syntactic silicone foam composition to foam, cure and consequently expand to fill the voids between adjacent battery cells during foaming and curing.

In one embodiment the battery cells are lithium-ion battery cells, alternatively cylindrical, prismatic or pouch lithium-ion battery cells, alternatively cylindrical, prismatic or pouch lithium-ion battery cells.

For the avoidance of doubt, silicone rubber syntactic foams are silicone rubber foams filled with hollow spheres, usually made from glass, which are often referred to as microballoons or cenospheres. A non-syntactic silicone foam composition means that the composition does not contain said hollow spheres, usually made from glass, which are often referred to as microballoons or cenospheres.

There is also provided a battery module having thermally insulated adjacent battery cells obtained or obtainable by following a process comprising the steps of the steps of :

(2) Dispensing a self-levelling, non-syntactic silicone foam composition into said housing, self-levelling, non-syntactic silicone foam composition comprising the following components:

(iv) one or more fire retardant fillers; and

In one embodiment the battery module is one of several battery modules in a battery pack.

There is further provided, a use of a self-levelling, non-syntactic silicone foam composition comprising the following components:

(iv) one or more fire retardant fillers; and

to provide a battery module having thermally insulated adjacent battery cells obtained or obtainable by following a process comprising the steps of :

(2) Dispensing said self-levelling, non-syntactic silicone foam composition into said housing, said self-levelling, non-syntactic silicone foam composition

(3) Allowing the self-levelling, non-syntactic silicone foam to flow within the housing and self-level and as such fill voids between adjacent battery cells in said battery module; and

There is also provided a two-part self-levelling, non-syntactic silicone foam composition comprising a part A composition of

(i) one or more polydiorganosiloxanes having a viscosity of from 100 to 20,000 mPa. s at 25℃ and at least two unsaturated groups per molecule selected from alkenyl and/or alkynyl groups; and

(ii) a catalyst comprising or consisting of a platinum group metal or a compound or complex thereof;

(iii) a chemical blowing agent, a physical blowing agent or a mixture of a chemical blowing agent and a physical blowing agent; and

a part B composition comprising

(iv) one or more fire retardant fillers;

(v) a cross-linker comprising an organosilicon compound having at least two alternatively at least three silicon bonded hydrogen groups per molecule;

such that component (ii) is only in the part A composition and components (iv) and (v) are only in the part B composition.

The process for thermally insulating adjacent battery cells in a battery module as hereinbefore described comprises the steps of :

(2) Dispensing the aforementioned self-levelling, non-syntactic silicone foam composition in the housing;

Each battery module as hereinbefore described is electrically interconnected with other battery modules in a battery pack. The electrical interconnection may be in series or in parallel, as required. Each battery module as hereinbefore described comprises a housing containing a plurality of battery cells. The individual battery cells in an article such as a battery module as hereinbefore described may be of any suitable shape, for example they may be prismatic, cylindrical or in a pouch form but must be electrically connectable with other cells within the battery module. For the process herein, whilst the cells may be of any type, it is believed the process is most suited for cylindrical cells, given the variable distances between adjacent cylindrical cells.

A battery module as hereinbefore described is required to provide mechanical and electrical interfaces to other battery modules and may also comprise, for the sake of example, cooling mechanisms, temperature monitors, voltage monitors and the like. Hence, the housing of a battery module as hereinbefore described is sized and designed to both accommodate a predetermined number of individual battery cells and if desired said other systems.

Battery module housings may be made from any suitable material, for example metals or injection moulded plastics and may also incorporate insert moldings in which interconnection strips and terminals are moulded into plastic parts. Small components and/or sub-assemblies may be encapsulated in the housing by any suitable means e.g. by over molding for ease of storage and/or protection.

The housing of a battery module as hereinbefore described (and/or individual battery cells therein) may comprise a thinning area or burst plate. This provides a weakened area in the housing which is designed to prevent the inner pressure within the battery module or battery to exceed a predetermined value. If a predetermined pressure value is reached due to the malfunction of one or more cells the weakening or burst plate will be forced open and will enable gases to escape thereby preventing further pressure build up within the battery cell or battery module concerned.

In one embodiment herein there is provided a battery pack comprising at least one battery module as described above, alternatively two or more battery modules as described above.

Battery pack designs for e.g. electric-vehicle batteries are complex but incorporate a combination of several simple mechanical and electrical component systems which perform the basic required functions of the pack. The battery packs therefore additionally comprise one or more of the following: -

(i) support electronics;

(ii) heaters (to extend the lower working temperature or cells) having their own control circuits;

(iii) heat dissipation members which are disposed between battery cells, and at least one heat exchange member. whereby heat generated from the battery cells during the charge and discharge of the battery cells is removed by the heat exchange member. The heat dissipation members may be made from a suitable thermally conductive material exhibiting high thermal conductivity and the heat exchange member is provided with one or more coolant channels for allowing a coolant such as a liquid or a gas to flow there;

(iv) coolers;

(v) Fixing points and methods and interconnections;

(vi) Control systems to keep the battery modules/cells within a predefined specified operating range e.g. for monitoring the battery status and controlling energy flows and to protect them from abuse;

(vii) fuel gauging means to estimate the state of charge (SOC) ; and/or

(viii) communications systems for communicating with other systems e.. other vehicle systems.

A battery pack as described above has to fit the space provided in the article for which it is providing power, e.g. a vehicle. This may dictate the shape of the battery modules and indeed individual cells and consequently the shape and/or form of the battery cells in a module and consequently the thermal insulation therebetween. The thermal insulation may be of variable thickness dependent on the shape of the individual cells, especially in the case of cylindrical batteries. The fact that the silicone foam composition herein is self-levelling means it can flow into the voids or voids between adjacent batteries irrespective of the geometry thereof and is able to completely fill all voids between batteries prior to and/or during foaming and cure to form thermally insulation filling all voids between adjacent batteries. The thermal insulation once fully foamed and cured is able to thermally isolate adjacent batteries from each other taking the shape of the voids between them and therefore is able to ensure insulation adjacent batteries substantially without any cavities in the thermal insulation generated. In some designs the battery pack forms part of the outer case of the end-product. The colours and textures of the battery pack housing must match the rest of the product. Such designs may be required to incorporate a mechanical connection means to hold the battery pack in place. Said mechanical connection means (e.g. a latch) , as well as electrical terminals and the like, must interface with other parts of the article to be powered by the battery pack. Any suitable material may be used for this, for example ABS polymers may be utilised.

The thermal insulation described above is designed to keep a battery cell malfunction localised within said battery module and in the event of a fire to prevent or at least delay the potential for thermal runaway propagation within the whole battery module so as to provide safety protection in the event of the thermal runaway of one battery cell in said battery module.

Therefore, when any one of the battery cells in a battery module as hereinbefore described releases heat abnormally due to short-circuit, overcharging, or other reasons, the thermal runaway of the cell concerned can be isolated to prevent or delay the propagation of thermal runaway through further cells in the battery module. The heat diffusion from the battery cell to the neighboring battery cells can be effectively insulated by the silicone foam insulation resulting from the process described herein. In addition, for some battery modules having control circuit boards disposed in the battery module housing, the composite heat conduction plate of the disclosure can be disposed between the battery and the circuit board and between battery and the connecting circuit to reduce the battery heating problem caused by the circuit board and the circuit.

As mentioned elsewhere, when a battery cell malfunctions, the heat generated causes a pressure build-up of gases initially within cell but ultimately if the cell fractures within. Such a pressure build-up can be to a pressure equal or greater than (≥) 0.9MPa and is caused by a build-up heated gas (such as CO ₂, CO, and H ₂) and/or liquid e.g. electrolyte resulting from the failed cell and/or battery module. Analysis of failure mode and behavior of lithium ion battery cells has indicated that, in the event of a thermal runaway in a battery cell occurring, temperatures may rise, for example, say 600℃ in 400sec and a consequential pressure build up to, for the sake of example 0.85MPa, alternatively 0.9MPa or even greater may occur in the event of a malfunctioning cell. A rupture disc housed on top of the cell is designed to rupture when the pressure reaches predetermined value such as e.g. 0.85MPa, alternatively 0.9MPa resulting in said gases and/or liquids e.g. electrolyte and decomposed liquid electrolytes being released from the malfunctioning cell. Even so, whilst this relieves the pressure build-up, e.g. the pressure will reduce to a more manageable level e.g. 0.3 MPa the cell remains at the excessively high temperature remains and if transferred to other cells in the battery module can initiate thermal run-away in the remaining cells in the battery module.

Having thermal insulation of silicone foam resulting from the method herein between adjacent battery cells avoids or delays thermal run-away to provide enough passenger evacuation time with the intention of providing enough time to enable the driver and passengers to exit a vehicle or the like.

The process described herein produces thermal insulation of any desired shape due to the self-levelling nature of the self-levelling, non-syntactic silicone foam composition and is therefore particularly suitable for dealing with modules containing cylindrical battery cells. By “self-levelling” we mean the non-syntactic, silicone foam composition will flow under the force of gravity sufficiently to provide intimate contact between the composition and the outer surfaces of the battery cells in the housing. This significantly decreases the potential for cavities and fissures in the thermal insulation between adjacent battery cells in the housing. The self-levelling also does away with the necessity of having to manipulate or tool the composition into difficult to reach positions within the housing and the self levelling nature means that prior to foaming and curing the self-levelling, non-syntactic silicone foam composition can surround battery cells relying on the effect of gravity and then can expand to fill the remainder of the housing when the composition foams and cures.

The process provides a thermally insulating foam between battery cells in said battery module such that in the event of a malfunction the thermal insulation will prevent the excessive heat increase from being immediately transferred to other nearby/adjacent battery cells.

In the second step of the process the aforementioned self-levelling, non-syntactic silicone foam composition is dispensed into the housing. The self-levelling, non-syntactic silicone foam composition is most likely to be stored in two or more parts as discussed in more detail below. Hence, before dispensing into the housing when the self-levelling, non-syntactic silicone foam composition is in two parts, typically referred to as part A and part B, the different parts are mixed together in a pre-determined weight ratio. The two parts may be pumped from storage to a suitable mixing and dispensing unit e.g. a static mixer and then after mixing is transported to a suitable dispensing means Typically once the parts A and B compositions are mixed, foaming will commence. The foaming composition may be transported to the dispensing head by a pump to control the cell size of the silicone elastomer foam generated. herein. The dispensing head may be controlled by using a pre-programmed or programable robot dispensing head which can be used to apply the composition to the target module. The dispensing head may, for example, be programed to apply an optimized amount of foam at a pre-determined dispensing flow rate. Typically, a predetermined amount of the self-levelling, non-syntactic silicone foam composition is dispensed into each housing.

In step 3 of the process the dispensed self-levelling, non-syntactic silicone foam composition is allowed to flow within the housing and self-level and as such fill voids between adjacent battery cells in said battery module.

In step 4 the self-levelling, non-syntactic silicone foam composition is allowed/enabled to cure and foam and consequently to expand to fill the voids between adjacent battery cells and if desired up to the ceiling of the housing.

Compositions described herein foam and cure when mixed at room temperature and humidity but heating may be used to accelerate cure if desired. Typically cure takes place at room temperature over a period of from 15 minutes to 1 hour, alternatively from 15 to 45 minutes, alternatively from 15 minutes to 40 minutes. After curing, the resulting thermal insulation may undergo post-curing. Post-curing can be utilised to stabilize the performance of thermal insulation material in a short time. Post cure, if utilised is typically undertaken at a temperature between room temperature (about 23 ℃ to 25℃) and about 75℃, alternatively about 40 ℃ and 70 ℃, alternatively between 50 and 70℃ for a period of e.g. 30 minutes to 3 hours, e.g. 1 hour.

The self-levelling, non-syntactic silicone foam composition, described herein, after parts A and B had been mixed, may be of any suitable viscosity where the composition is able to self-level in the module subsequent to being dispensed therein; for example the composition may have a viscosity of from 500 to 20,000mPa. s at 25℃, alternatively 500 to 15,000mPa. s at 25℃, 500 to 10,000mPa. s at 25℃, alternatively 500 to 5,000mPa. s at 25℃. The viscosity measurements of the final composition after parts A and B had been mixed were carried out in accordance with ASTM D1084 using a Brookfield spindle LV-3 at 100 rpm. Preferably the viscosity measurement is taken prior to or at the start of the cure of the self-levelling, non-syntactic silicone foam composition, or immediately after dispensing. The viscosity of the final composition after parts A and B have been mixed may be carried out in accordance with ASTM D1084 using a Brookfield spindle LV-3 at 100rpm. One or more components of the self-levelling, non-syntactic silicone foam composition may have a viscosity which is greater than the overall viscosity of the composition, providing when all components and additives are mixed together the viscosity of the final composition is within the range specified. In one embodiment the viscosity of the self-levelling, non-syntactic silicone foam composition is greater than (>) the viscosity of each individual component present.

The self-levelling, non-syntactic silicone foam composition used in the process described herein, comprises five components and may, if desired, contain one or more additives as discussed below.

Component (i) of the self-levelling, non-syntactic silicone foam composition used in the process described herein is one or more polydiorganosiloxanes having at least two unsaturated groups per molecule, alternatively at least three unsaturated groups per molecule selected from alkenyl and/or alkynyl groups;

The unsaturated groups of component (i) may be terminal, pendent, or in both locations in component (i) . For example, the unsaturated group may be an alkenyl group and/or an alkynyl group. Alkenyl is exemplified by, but not limited to, vinyl, allyl, 2-methyl-allyl, propenyl, and hexenyl groups. Alkenyl groups may have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, and alternatively 2 to 6 carbon atoms. Alkynyl may be exemplified by, but not limited to, ethynyl, propynyl, and butynyl groups. Alkynyl groups may have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, and alternatively 2 to 6 carbon atoms.

Component (i) has multiple units of the formula (I) :

R _aSiO _(4-a) /2 (I)

in which each R is independently selected from an aliphatic hydrocarbyl, aromatic hydrocarbyl, or organyl group (that is any organic substituent group, regardless of functional type, having one free valence at a carbon atom) . Saturated aliphatic hydrocarbyls are exemplified by, but not limited to alkyl groups such as methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl and cycloalkyl groups such as cyclohexyl. Unsaturated aliphatic hydrocarbyls are exemplified by, but not limited to the alkenyl groups and alkynyl groups described above. Aromatic hydrocarbon groups are exemplified by, but not limited to, phenyl, tolyl, xylyl, benzyl, styryl, and 2-phenylethyl. Organyl groups are exemplified by, but not limited to, halogenated alkyl groups (excluding fluoro containing groups) such as chloromethyl and 3-chloropropyl; nitrogen containing groups such as amino groups, amido groups, imino groups, imido groups; oxygen containing groups such as polyoxyalkylene groups, carbonyl groups, alkoxy groups and hydroxyl groups. Further organyl groups may include sulfur containing groups, phosphorus containing groups, boron containing groups. The subscript “a” is 0, 1, 2 or 3.

Siloxy units may be described by a shorthand (abbreviated) nomenclature, namely - "M, " "D, " "T, " and "Q" , when R is a methyl group (further teaching on silicone nomenclature may be found in Walter Noll, Chemistry and Technology of Silicones, dated 1962, Chapter I, pages 1-9) . The M unit corresponds to a siloxy unit where a = 3, that is R ₃SiO _1/2; the D unit corresponds to a siloxy unit where a = 2, namely R ₂SiO _2/2; the T unit corresponds to a siloxy unit where a = 1, namely R ₁SiO _3/2; the Q unit corresponds to a siloxy unit where a = 0, namely SiO _4/2. The polydiorganosiloxane of component (i) is substantially linear but may contain a proportion of however, there can be some branching due to the presence of T units (as previously described) within the molecule, hence the average value of a in structure (I) is about 2.

Examples of typical groups on component (i) include mainly alkenyl, alkynyl, alkyl, and/or aryl groups, alternatively alkenyl, alkyl, and/or aryl groups. The groups may be in pendent position (on a D or T siloxy unit) or may be terminal (on an M siloxy unit) .

The silicon-bonded organic groups attached to component (i) other than alkenyl groups are typically selected from monovalent saturated hydrocarbon groups, which typically contain from 1 to 10 carbon atoms, and monovalent aromatic hydrocarbon groups, which typically contain from 6 to 12 carbon atoms, which are unsubstituted or substituted with the groups that do not interfere with curing of this inventive composition, such as halogen atoms. Preferred species of the silicon-bonded organic groups are, for example, alkyl groups such as methyl, ethyl, and propyl; and aryl groups such as phenyl.

Component (i) may be selected from polydimethylsiloxanes, alkylmethylpolysiloxanes, alkylarylpolysiloxanes or copolymers thereof (where reference to alkyl means an alkyl group having two or more carbons) containing e.g. alkenyl and/or alkynyl groups and may have any suitable terminal groups, for example, they may be trialkyl terminated, alkenyldialkyl terminated alkynyldialkyl terminated or may be terminated with any other suitable terminal group combination providing each polymer contains at least two unsaturated groups selected from alkenyl and alkynyl groups per molecule. In one embodiment the terminal groups of such a polymer has no silanol terminal groups.

Hence component (i) may, for the sake of example, be: a dialkylalkenyl terminated polydimethylsiloxane, e.g. dimethylvinyl terminated polydimethylsiloxane; a dialkylalkenyl terminated dimethylmethylphenylsiloxane, e.g. dimethylvinyl terminated dimethylmethylphenylsiloxane; a trialkyl terminated dimethylmethylvinyl polysiloxane; a dialkylvinyl terminated dimethylmethylvinyl polysiloxane copolymer; a dialkylvinyl terminated methylphenylpolysiloxane, a dialkylalkenyl terminated methylvinylmethylphenylsiloxane; a dialkylalkenyl terminated methylvinyldiphenylsiloxane; a dialkylalkenyl terminated methylvinyl methylphenyl dimethylsiloxane; a trimethyl terminated methylvinyl methylphenylsiloxane; a trimethyl terminated methylvinyl diphenylsiloxane; or a trimethyl terminated methylvinyl methylphenyl dimethylsiloxane.

In these embodiments, at a temperature of 25 ℃, the generally substantially linear organopolysiloxane of component (i) is typically a flowable liquid. Generally, the substantially linear organopolysiloxane has a viscosity of from having a viscosity of from 100 to 20,000 mPa. s at 25℃ mPa. s, alternatively from 200 to 2000 mPa. s, at 25 ℃. Viscosity may be measured at 25 ℃using either a

rotational viscometer with spindle LV-3 (designed for viscosities in the range between 200-400,000 mPa. s) or a

rotational viscometer with spindle LV-1 (designed for viscosities in the range between 15 -20,000mPa. s) for viscosities less than 1000mPa. s and adapting the speed according to the polymer viscosity. Component (i) may be present in the composition in an amount of from 30 to 70 wt. %of the composition, alternatively 30 to 65 wt. %of the composition.

Component (ii) of the self-levelling, non-syntactic silicone foam composition described herein is a catalyst comprising or consisting of a platinum group metal or a compound or complex thereof. By “platinum group” it is meant ruthenium, rhodium, palladium, osmium, iridium and platinum. Platinum and platinum compounds or complexes are preferred due to the high activity level of these catalysts in hydrosilylation reactions.

Examples of preferred hydrosilylation catalysts (ii) include but are not limited to platinum black, platinum on various solid supports, chloroplatinic acids, alcohol solutions of chloroplatinic acid, and complexes of chloroplatinic acid with ethylenically unsaturated compounds such as olefins and organosiloxanes containing ethylenically unsaturated silicon-bonded hydrocarbon groups. The catalyst (ii) can be platinum metal, platinum metal deposited on a carrier, such as silica gel or powdered charcoal, or a compound or complex of a platinum group metal.

Examples of suitable platinum-based catalysts include complexes of chloroplatinic acid with organosiloxanes containing ethylenically unsaturated hydrocarbon groups are described in US 3,419,593;

chloroplatinic acid, either in hexahydrate form or anhydrous form;

a platinum-containing catalyst which is obtained by a method comprising reacting chloroplatinic acid with an aliphatically unsaturated organosilicon compound, such as divinyltetramethyldisiloxane;

alkene-platinum-silyl complexes as described in US Pat. No. 6,605,734 such as (COD) Pt (SiMeCl ₂) ₂ where “COD” is 1, 5-cyclooctadiene; and/or

Karstedt's catalyst, a platinum divinyl tetramethyl disiloxane complex typically containing about 1 wt. %of platinum in a solvent, such as toluene may be used. These are described in US3,715,334 and US3,814,730.

The hydrosilylation catalyst (ii) is present in the total composition in a catalytic amount, i.e. an amount or quantity sufficient to promote a reaction or curing thereof at desired conditions. Varying levels of the hydrosilylation catalyst (ii) can be used to tailor reaction rate and cure kinetics. The catalytic amount of the hydrosilylation catalyst (ii) is generally between 0.01 ppm, and 10,000 parts by weight of platinum-group metal, per million parts (ppm) , based on the combined weight of the composition components (i) and (v) ; alternatively, between 0.01 and 5000 ppm; alternatively between 0.01 and 3,000 ppm, and alternatively between 0.01 and 1,000 ppm. In specific embodiments, the catalytic amount of the catalyst may range from 0.01 to 1,000 ppm, alternatively 0.01 to 750 ppm, alternatively 0.01 to 500 ppm and alternatively 0.01 to 100 ppm of metal based on the weight of the composition. The ranges may relate solely to the metal content within the catalyst or to the catalyst altogether (including its ligands) as specified, but typically these ranges relate solely to the metal content within the catalyst. The catalyst may be added as a single species or as a mixture of two or more different species. Typically, dependent on the form/concentration in which the catalyst package is provided the amount of catalyst present will be within the range of from 0.001 to 3.0 wt. %of the composition.

Component (iii) of the self-levelling, non-syntactic silicone foam composition used in the process described herein is a chemical blowing agent, a physical blowing agent or a mixture of a chemical blowing agent and a physical blowing agent.

When component (iii) comprises a chemical blowing agent, it comprises one or more hydroxyl-containing blowing agents which will react with the cross-linker (v) in the presence of component (ii) the catalyst. When component (iii) is a chemical blowing agent, comprising one or more hydroxyl-containing blowing agents, each hydroxyl-containing blowing agent has at least one OH group, alternatively at least two OH groups, and alternatively three or more OH groups. The OH group (s) can react with the Si-H groups of component (v) , thereby generating hydrogen gas, which is relied upon to generate the foam. Each hydroxyl-containing blowing agent may be a suitable alcohol. These may be selected from aliphatic organic alcohols having from 1 to 12 carbon atoms such as low molecular weight alcohols including, but are not limited to, methanol, ethanol, propanol, isopropanol, and the like or alternatively, benzyl alcohol.

In one embodiment a hydroxyl-containing blowing agent may be a diol. Examples of suitable diols include, but are not limited to, methylene glycol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butane diol, bisphenol A, 1, 4-butanediol, 1, 3-propanediol, 1, 5-pentanediol, 1, 7-heptanediol, 1, 2-hexanediol, triethylene glycol, tripropylene glycol neopentyl glycol, and combinations thereof. Alternatively, a hydroxyl-containing blowing agent may be a triol.

In various embodiments, component (iii) , when a hydroxyl-containing blowing agent is selected from the group of low-boiling alcohols. Such alcohols generally have a boiling point lower than about 120℃. The alcohols may or may not be anhydrous, but anhydrous (containing less than 1 wt. %) water based on weight of alcohol is generally preferred. Other suitable blowing agents are described in US4550125, US6476080, and US20140024731, which are incorporated herein by reference.

Component (iii) when a hydroxyl-containing blowing agent is present in an amount to provide an OH content of from about 10 parts per million (ppm) to 50,000ppm, alternatively about 100ppm to 20,000ppm, alternatively about 500ppm to 10,000 ppm, alternatively about 500 to about 7500 ppm.

In other embodiments, when component (iii) is a chemical blowing agent, the chemical blowing agent may be selected from the group of Si-OH polymers. In certain embodiments, when a chemical blowing agent, component (iii) is selected from the group consisting of organosilanes and organosiloxanes having at least one silanol (Si-OH) group. Such compounds can have structures similar to those for the polymers described above for component (i) . Examples of suitable OH-functional compounds include dialkyl siloxanes, such as OH-terminated dimethyl siloxanes. Such siloxanes may have a relatively low viscosity, such as about 15 to about 20,000mPa. s, about 15 to about 10,000mPa. s, about 15 to about 5,000 mPa. s, about 15 to about 1,000 mPa. s, or about 15 to about 100 mPa. s. measured at 25℃. Viscosity may be measured at 25 ℃ using either a

rotational viscometer with spindle LV-3 (designed for viscosities in the range between -200-400,000mPa. s) or a

rotational viscometer with spindle LV-1 (designed for viscosities in the range between 15 -20,000mPa. s) for viscosities less than 200 mPa. s and adapting the speed according to the polymer viscosity.

Alternatively, component (iii) may comprise a physical liquid blowing agent. When component (iii) is a physical liquid blowing agent, said physical liquid blowing agent is tailored to undergo a phase change at the temperature of application. When component (iii) is a physical blowing agent said phase change at the temperature of application is the main source for the gas that leads to the formation of the foam by replacing all or most of the hydrogen gas generated when using a chemical blowing agent.

When component (iii) is a physical blowing agent, the physical blowing agent chosen is selected in accordance with its boiling point such that it undergoes a phase change from a liquid to a gaseous state during exposure to atmospheric pressure and the temperature of the cure process, e.g. a temperature less than or equal to 10℃, alternatively less than or equal to 20℃, alternatively less than or equal to 30℃, alternatively less than or equal to 40℃, alternatively less than or equal to 50℃, alternatively less than or equal to 60℃, alternatively less than or equal to 70℃, alternatively less than or equal to 80℃, alternatively less than or equal to 90℃, alternatively less than or equal to 100℃. In the case of room temperature vulcanization systems, the physical blowing agent chosen may have a boiling point of between 10 and 30℃, i.e. such that it undergoes a phase change from a liquid to a gaseous state during exposure to atmospheric pressure within this temperature range.

The amount of physical blowing agent utilized, when component (iii) is a physical blowing agent, can vary depending on the desired outcome. For example, the amount of physical blowing agent can be varied to tailor final foam density and foam rise profile of the resulting thermal insulation.

Useful physical blowing agents include hydrocarbons, such as pentane, hexane, halogenated, more particularly chlorinated and/or fluorinated, hydrocarbons, for example methylene chloride, chloroform, trichloroethane, chlorofluorocarbons, hydrochlorofluorocarbons (HCFCs) , ethers, ketones and esters, for example methyl formate, ethyl formate, methyl acetate or ethyl acetate, in liquid form or air, nitrogen or carbon dioxide as gases. In certain embodiments, the physical blowing agent comprises a compound selected from the group consisting of propane, butane, isobutane, isobutene, isopentane, dimethylether or mixtures thereof. In many embodiments, the blowing agent comprises a compound that is inert.

In various embodiments, the physical blowing agent comprises a hydrofluorocarbon (HFC) . “Hydrofluorocarbon” and “HFC” are interchangeable terms and refer to an organic compound containing hydrogen, carbon, and fluorine. The compound is substantially free of halogens other than fluorine.

Examples of suitable HFCs include aliphatic compounds such as 1, 1, 1, 3, 3-pentafluoropropane, 1, 1, 1, 3, 3-pentafluorobutane , 1-fluorobutane, nonafluorocyclopentane, perfluoro-2-methylbutane, 1-fluorohexane, perfluoro-2, 3-dimethylbutane, perfluoro-1, 2-dimethylcyclobutane, perfluorohexane, perfluoroisohexane, perfluorocyclohexane, perfluoroheptane, perfluoroethylcyclohexane, perfluoro-1, 3-dimethyl cyclohexane, and perfluorooctane; as well as aromatic compounds such as fluorobenzene, 1, 2-difluorobenzene; 1, 4-difluorobenzene, 1, 3-difluorobenzene; 1, 3, 5-trifluorobenzene; 1, 2, 4, 5-tetrafluorobenzene, 1, 2, 3, 5-tetrafluorobenzene, 1, 2, 3, 4-tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and 1-fluro-3- (trifluoromethyl) benzene. In certain embodiments, compounds such as 1, 1, 1, 3, 3-pentafluoropropane and 1, 1, 1, 3, 3-pentafluorobutane may be preferred due to their increasing availability and ease of use, with 1, 1, 1, 3, 3-pentafluorobutane having a higher boiling point than 1, 1, 1, 3, 3-pentafluoropropane which may be useful in certain applications. For example, HFCs having a boiling point higher than 30℃, such as 1, 1, 1, 3, 3-pentafluorobutane, may be desirable because they do not require liquefaction during foam processing. In specific embodiments, when component (iii) is a physical blowing agent, component (iii) comprises 1, 1, 1, 3, 3-pentafluoropropane.

If desired component (iii) of the self-levelling, non-syntactic silicone foam composition in the process described herein may alternatively be a mixture of a chemical blowing agent as described above and of a physical blowing agent as described above. Component (iii) is typically present in the composition in an amount of from 2 to about 20 wt. %of the composition, alternatively from 2 to about 15 wt. %of the composition.

Component (iv) of the self-levelling, non-syntactic silicone foam composition in the process described herein is one or more fire retardant fillers selected from the group of wollastonite, aluminium trihydrate, magnesium hydroxide, halloysite, huntite hydromagnesite, expandable graphite, zinc borate, mica or a fumed silica. The fire-retardant fillers, when present may optionally be surface treated with a treating agent. The treating agents used may be selected from one or more of, for example, organosilanes, polydiorganosiloxanes, or organosilazanes, hexaalkyl disilazane, short chain siloxane diols, a fatty acid or a fatty acid ester such as a stearate to render one or more of the filler (s) hydrophobic and therefore easier to handle and obtain a homogeneous mixture with the other components. Specific examples include but are not limited to liquid hydroxyl-terminated polydiorganosiloxane containing an average from 2 to 20 repeating units of diorganosiloxane in each molecule which may optionally contain fluoro groups and or fluoro containing groups, if desired, hexaorganodisiloxane, hexaorganodisilazane, and the like. Component (iv) , the filler, may be present in any suitable amount for example from 10 to 50 wt. %of the composition.

Component (v) of the self-levelling, non-syntactic silicone foam composition described herein is a cross-linker comprising an organosilicon compound having at least two, alternatively at least three silicon bonded hydrogen groups per molecule. Component (v) operates as a cross-linker for curing component (i) , by the addition reaction of the silicon-bonded hydrogen atoms with the unsaturated groups in component (i) catalysed by component (ii) described above. Component (v) normally contains three or more silicon-bonded hydrogen atoms so that the hydrogen atoms of this component can sufficiently react with the unsaturated groups of component (i) to form a network structure therewith and thereby cure the composition. Some or all of Component (v) may alternatively have two silicon bonded hydrogen atoms per molecule when component (i) has greater than (>) 2 unsaturated groups, alternatively alkenyl groups per molecule.

Component (v) may be a siloxane e.g. an organohydrogensiloxane or a silane e.g. a monosilane, disilane, trisilane, or polysilane providing each molecule has at least two, alternatively at least three Si-H groups per molecule. In acyclic polysilanes and polysiloxanes, the silicon-bonded hydrogen atoms can be located at terminal, pendant, or at both terminal and pendant positions. Cyclosilanes and cyclosiloxanes typically have from 3 to 12 silicon atoms, alternatively from 3 to 10 silicon atoms, alternatively from 3 to 4 silicon atoms.

When component (v) is a siloxane it may comprise an organohydrogensiloxane, which can be a disiloxane, trisiloxane, or polysiloxane. The organohydrogensiloxane, may comprise any combination of M, D, T and/or Q siloxy units, so long as component (v) includes at least two silicon-bonded hydrogen atoms. These siloxy units can be combined in various manners to form cyclic, linear, branched and/or resinous (three-dimensional networked) structures. Component (v) may be monomeric, polymeric, oligomeric, linear, branched, cyclic, and/or resinous depending on the selection of M, D, T, and/or Q units.

Examples of component (v) include but are not limited to: trimethylsiloxy-terminated methylhydrogenpolysiloxane, trimethylsiloxy-terminated polydimethylsiloxane-methylhydrogensiloxane, dimethylhydrogensiloxy-terminated dimethylsiloxane-methylhydrogensiloxane copolymers, dimethylsiloxane-methylhydrogensiloxane cyclic copolymers, copolymers composed of (CH ₃) ₂HSiO _1/2 units and SiO _4/2 units, copolymers composed of (CH ₃) ₃SiO _1/2 units, (CH ₃) ₂HSiO _1/2 units, and SiO _4/2 units; and copolymers containing (CH ₃) ₂HSiO _1/2 units and (R ²Z) _d (R ³) _e SiO _(4-d-e) /2 as described above.

While the viscosity of this component is not specifically restricted, it may typically be from 5 -1,000 mPa. s at 25℃, alternatively 5 -500 mPa. s at 25℃, alternatively 5 -100 mPa. s at 25℃, alternatively 5 -50mPa. s at 25℃, alternatively 5-20 mPa. s at 25℃using a

rotational viscometer with spindle LV-1 (designed for viscosities in the range between 15 -20,000mPa. s) and adapting the speed according to the polymer viscosity, or a

rotational viscometer with spindle YULA-15 (E) (designed for viscosities in the range between 1 -2000 mPa. s) for viscosities less than 15 mPa. s and adapting the speed according to the polymer viscosity.

Component (v) is typically added in an amount such that the molar ratio of the silicon-bonded hydrogen atoms in component (v) to that of all unsaturated groups in the composition and the number of -OH groups in component (iii) , when a chemical blowing agent, is from 0.5: 1 to 20: 1; alternatively of from 0.5 : 1 to 5 : 1, alternatively from 0.6 : 1 to 3 : 1. When this ratio is less than 0.5: 1, a well-cured composition will not be obtained. When the ratio exceeds 20: 1, there is a tendency for the hardness of the cured composition to increase when heated. The amounts of each group mentioned in the above ratio, e.g. silicon-bonded hydrogen (Si-H) content of organohydrogenpolysiloxane (v) may be determined using quantitative infra-red analysis in accordance with ASTM E168, if desired.

Typically component (v) is present in the composition in an amount of from 0.5 to10 wt. %of the total composition which amount is determined dependent on the required molar ratio of the total number of the silicon-bonded hydrogen atoms in component (v) to the total number of all alkenyl and alkynyl groups in component (i) and the amount of hydroxyl groups in component (iii) when a chemical blowing agent.

The self-levelling, non-syntactic silicone foam compositions as described in the process herein are usually stored in two parts to avoid premature cure. The two parts are generally referred to as part A and part B. Two-part compositions are utilised so that that components (i) polymer, (v) cross-linker, (iii) blowing agent and (ii) catalyst are not all stored together. For example, Part A may comprise components (i) , (ii) and part or all of (iii) and Part B comprises at least components (i) and (v) and typically components (i) and (v) and part of (iii) with part A free of component (v) cross-linker and part B free of component (ii) catalyst. Typically, component (iii) blowing agent and Component (iv) , the filler may be partially in the part A composition and partially in the part B composition.

In one embodiment, as indicated above, there is provided a two-part self-levelling, non-syntactic silicone foam composition comprising a part A composition of component (i) , component (ii) and component (iii) and a part B composition of component (i) , component (iv) and component (v) such that components (ii) and (iii) are only in the part A composition and components (iv) and (v) are only in the part B composition.

It was found in the latter embodiment that by only having component (iii) blowing agent in Part A, and only having component (iv) filler in Part B, processing be improved compared with the standard where filler and blowing agent are equally distributed in both Part A and Part B. This is because if the filler begins to settle, oil migration occurs, and the appropriate part in which this happens has to be remixed before use. The fact that component (iii) blowing agents are usually designed to have low boiling points due to their function in the process any remixing to render said component homogeneous again can result in the generation of heat during remixing. It was found that by separating component (iii) and component (iv) by having all component (iii) in part A and all component (iv) in part B this is no longer an issue as the part B composition can be remixed as and when necessary and the filler settling issue no longer occurs in part A.

The part A and part B of the two part composition may be designed to be mixed together in any suitable ratio dependent on the content and concentration of the ingredients present in each part, for example the two part composition may be mixed in a Part A : Part B weight ratio of from 15 : 1 to 1 : 10, alternatively from 15 : 1 to 1 : 5, alternatively from 15 : 1 to 1 : 2.5, alternatively from 10 : 1 to 1 : 2.5. Typically, the part A : part B ratio is less than 1 : 1, i.e. between 1 : 1 and 1 : 5 when using the embodiment where all filler is added into to the Part B composition and all blowing agent is added to the to the Part A composition.

Before being mixed together in the above process the ingredients of the part A composition are blended together and separately the ingredients of the part B composition are also blended together to form respective part A and part B compositions.

The composition may include one or more optional additives but the total weight %of the composition is 100 wt. %. The alkenyl and/or alkynyl content of polymer (i) is determined using quantitative infra-red analysis in accordance with ASTM E168.

The self-levelling, non-syntactic silicone foam compositions as described in the process herein may optionally further comprise additional ingredients or components (hereafter referred to as “additives” ) . Examples of additional ingredients include, but are not limited to, resins, inhibitors; surfactants; stabilizers; adhesion promoters; colorants, including dyes and pigments; anti-oxidants; carrier vehicles; heat stabilizers; flame retardants; flow control additives; inhibitors; non-reinforcing (sometimes referred to as extending) fillers.

The one or more additives can be present in a suitable wt. %of the composition. When present the additive may be present in an amount of up to about 10 or even 15 wt. %based on the understanding that the total wt. %of the composition is 100 wt. %. One of skill in the art can readily determine a suitable amount of additive depending, for example, on the type of additive and the desired outcome. Certain optional additives are described in greater detail below.

For example, The composition may further comprise an organopolysiloxane resin ( “resin” ) as a resin foam stabilizer. The resin has a branched or a three-dimensional network molecular structure. At 25℃, the resinous organopolysiloxane may be in a liquid or in a solid form, optionally dispersed in a carrier, which may solubilize and/or disperse the resin therein.

In specific embodiments, the resinous organopolysiloxane may be exemplified by an organopolysiloxane that comprises only T units, an organopolysiloxane that comprises T units in combination with other siloxy units (e.g. M, D, and/or Q siloxy units) , or an organopolysiloxane comprising Q units in combination with other siloxy units (i.e., M, D, and/or T siloxy units) . Typically, the resin comprises T and/or Q units. Specific examples are alkenylated silsesquioxanes or MQ resins e.g. vinyl terminated silsesquioxanes or MQ resins.

For example, the resin may be formed from multiple groups of formula:

R ⁵ _f"SiO _(4-f") /2

wherein each R ⁵ is a substituted or unsubstituted monovalent hydrocarbon group of 1 to 20 carbon atoms, for example, alkyl groups such as methyl, ethyl, propyl, hexyl, octyl, dodecyl, tetradecyl, hexadecyl, and octadecyl, or an aromatic group having 6 to 20 carbons such as benzyl and phenylethyl groups or alkenyl groups such as vinyl, propenyl, n-butenyl, t-butenyl, pentenyl, hexenyl, octenyl and the like and wherein each f" is from 0 to 4. If the resin is a T resin, then most groups have f" as 1 and if the resin is an MQ resin to largely comprises groups where f" is 0 (Q groups) or 4 (M groups) as previously discussed.

Suitable pigments may include carbon black, e.g. acetylene black, titanium dioxide, chromium oxide, zinc oxide, bismuth vanadium oxide, iron oxides and mixtures thereof.

The composition as described herein may further comprise a hydrosilylation reaction inhibitor to inhibit the cure of the composition. Hydrosilylation reaction inhibitors are used, when required, to prevent or delay the hydrosilylation reaction curing process especially during storage. The optional hydrosilylation reaction inhibitors of platinum based catalysts are well known in the art and include hydrazines, triazoles, phosphines, mercaptans, organic nitrogen compounds, acetylenic alcohols, silylated acetylenic alcohols, maleates, fumarates, ethylenically or aromatically unsaturated amides, ethylenically unsaturated isocyanates, olefinic siloxanes, unsaturated hydrocarbon monoesters and diesters, conjugated ene-ynes, such as 3-methyl-3-penten-1-yne, 3, 5-dimethyl-3-hexen-1-yne hydroperoxides, nitriles, and diaziridines. Alkenyl-substituted siloxanes as described in US3989667 may be used, of which cyclic methylvinylsiloxanes such as 1, 3, 5, 7-tetramethyl-1, 3, 5, 7-tetravinylcyclotetrasiloxane, 1, 3, 5, 7-tetramethyl-1, 3, 5, 7-tetrahexenylcyclotetrasiloxane, are preferred.

One class of known hydrosilylation reaction inhibitor includes the acetylenic compounds disclosed in US3445420. Acetylenic alcohols such as 2-methyl-3-butyn-2-ol constitute a preferred class of inhibitors that will suppress the activity of a platinum-containing catalyst at 25 ℃. Compositions containing these inhibitors typically require heating at temperature of 70 ℃ or above to cure at a practical rate.

Examples of acetylenic alcohols and their derivatives include 3-methyl-1-butyn-3-ol, 1-ethynyl-1-cyclohexanol (ETCH) , 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-butyn-2-ol, propargyl alcohol, 1-phenyl-2-propyn-1-ol, 3, 5-dimethyl-1-hexyn-3-ol, 3-phenyl-1-butyn-3-ol, 1-ethynylcyclopentanol, 3-methyl-1-penten-4-yn-3-ol, and mixtures thereof. Derivatives of acetylenic alcohol may include those compounds having at least one silicon atom.

When present, inhibitor concentrations as low as 1 mole of inhibitor per mole of the metal of catalyst will in some instances impart satisfactory storage stability and cure rate. In other instances, inhibitor concentrations of up to 500 moles of inhibitor per mole of the metal of catalyst are required. The optimum concentration for a given inhibitor in a given composition is readily determined by routine experimentation. Dependent on the concentration and form in which the inhibitor selected is provided/available commercially, when present in the composition, the inhibitor is typically present in an amount of from 0.0125 to 10 wt. %of the composition.

In various embodiments, the composition further comprises an adhesion promoter. The adhesion promoter can improve adhesion of the foam to a substrate being contacted during curing. In certain embodiments, the adhesion promoter is selected from organosilicon compounds having at least one alkoxy group bonded to a silicon atom in a molecule. This alkoxy group is exemplified by a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and a methoxyethoxy group. Moreover, non-alkoxy groups bonded to a silicon atom of this organosilicon compound are exemplified by substituted or non-substituted monovalent hydrocarbon groups such as alkyl groups, alkenyl groups, aryl groups, aralkyl groups, halogenated alkyl groups and the like; epoxy group-containing monovalent organic groups such as a 3-glycidoxypropyl group, a 4-glycidoxybutyl group, or similar glycidoxyalkyl groups; a 2- (3, 4-epoxycyclohexyl) ethyl group, a 3- (3, 4-epoxycyclohexyl) propyl group, or similar epoxycyclohexylalkyl groups; and a 4-oxiranylbutyl group, an 8-oxiranyloctyl group, or similar oxiranylalkyl groups; acrylic group-containing monovalent organic groups such as a 3-methacryloxypropyl group and the like; and a hydrogen atom.

This organosilicon compound generally has a silicon-bonded alkenyl group or silicon-bonded hydrogen atom. Moreover, due to the ability to impart good adhesion with respect to various types of substrates, this organosilicon compound generally has at least one epoxy group-containing monovalent organic group in a molecule. This type of organosilicon compound is exemplified by organosilane compounds, organosiloxane oligomers and alkyl silicates. Molecular structure of the organosiloxane oligomer or alkyl silicate is exemplified by a linear chain structure, partially branched linear chain structure, branched chain structure, ring-shaped structure, and net-shaped structure. A linear chain structure, branched chain structure, and net-shaped structure are typical. This type of organosilicon compound is exemplified by silane compounds such as 3-glycidoxypropyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) -ethyltrimethoxysilane, 3-methacryloxy propyltrimethoxysilane, and the like; siloxane compounds having at least one silicon-bonded alkenyl group or silicon-bonded hydrogen atom, and at least one silicon-bonded alkoxy group in a molecule; mixtures of a silane compound or siloxane compound having at least one silicon-bonded alkoxy group and a siloxane compound having at least one silicon-bonded hydroxyl group and at least one silicon-bonded alkenyl group in the molecule; and methyl polysilicate, ethyl polysilicate, and epoxy group-containing ethyl polysilicate.

When using one or more additives in addition to components (i) to (v) of the composition as described above, the part A composition might also include one or more of the aforementioned optional components such as inhibitor (depending on the choice of inhibitor) , pigments or colorants and/or an MQ resin foam stabilizer.

The part B blend composition might also include one or more of the aforementioned optional components such inhibitor (depending on the choice of inhibitor) , pigments or colorants and/or an MQ resin foam stabilizer. Alternatively, a proportion of said additives may be present in each both the part A and part B composition if desired.

Typically the part A and part B compositions are stored for a period of time before use. In step (i) the part A composition and part B compositions are mixed to form a foam of the self-levelling, non-syntactic silicone foam composition described above. Any suitable mixer may be used, for example the mixer may be a static mixer or a stirred tank or the like suitable for undertaking thorough mixing of the respective blend compositions. Optionally the mixing container is temperature controllable such that the part A composition and part B compositions being mixed can be maintained within a desired temperature range.

For the avoidance of doubt it is to be understood that in the above and all other references to %weight (%wt. ) of the composition in this disclosure, the total %wt. of all compositions is in all instances is 100%.

The self-levelling, non-syntactic silicone foam compositions as described herein produce open cell and/or closed cell foams. When the foam is a closed cell foam the density may be measured by any suitable method such as via the Archimedes principle, using a balance and density kit, and following standard instructions associated therewith. A suitable balance is a Mettler-Toledo XS205DU balance with density kit. When a closed cell foam it may have a density of from 0.01 grams per cubic centimeter g/cm ³ to 5 g/cm ³, alternatively from 0.05 g/cm ³ to 2.5 g/cm ³ alternatively from 0.1 g/cm ³ to 2.0 g/cm ³, alternatively from 0.1 g/cm ³ to 1.5 g/cm ³.

If density is too high, the foam may be too heavy or stiff for certain applications. If density is too low, the foam may lack desired structural integrity for certain applications.

The average pore size can be determined via any suitable method such as in accordance with ATSM method D3576-15 optionally with the following modifications:

(1) image a foam using optical or electron microscopy rather than projecting the image on a screen; and

(2) scribe a line of known length that spans greater than 15 cells rather than scribing a 30 mm line.

The self-levelling, non-syntactic silicone foam compositions as described herein generally has pores that are uniform in size and/or shape. Typically, the foam has an average pore size of between 0.001mm and 5mm, alternatively between 0.001mm and 2.5mm, alternatively between 0.001mm and 1mm, alternatively between 0.001mm and 0.5mm, alternatively between 0.001mm and 0.25mm, alternatively between 0.001mm and 0.1mm, and alternatively between 0.001mm and 0.05mm.

Description of the Figures

Fig. 1 is a depiction of a battery module with a set of battery cells in place and partially electrically connected;

Fig. 2 depicts the process for preparing and dispensing the composition described in the process into the battery module containing a series of battery cells introduce a two-part composition;

Fig. 3 is a depiction of an insulated series of battery cells after foaming and curing process with the housing of the module removed;

Figs. 4a and 4b are two alternate depictions of the thermal insulation cured from the self-levelling, non-syntactic silicone foam composition herein in the absence of cylindrical battery cells.

Fig. 1 is a depiction of a battery module (10) having a housing (12) containing multiple cylindrical lithium ion batteries (20) . The lithium ion batteries (20) are held in a base mold, not shown, which separates the batteries, which together forms the basic internals of a cell module. It can be seen that because of the shape of the batteries the voids between them are of an irregular geometry which in the case of Fig. 1 voids are not filled by any thermal insulation or the like.

Fig. 2 depicts the process described herein. During the process, the part A composition is prepared and deposited in tank (1) and the part B composition is prepared and deposited in tank (2) . The part A composition is pumped from tank (1) through valve (5) using pump (3) to mixer (7) . In an analogous fashion the part B composition is pumped from tank (2) through valve (6) using pump (4) to mixer (7) . The part A and part B compositions are mixed together in mixer (7) whereafter foaming will commence en route to dispensing head (8) . Dispensing head (8) is used to dispense self-levelling, non-syntactic silicone foam composition as hereinbefore described or comparatives C. 1 or C. 2 into the housing (12) of battery module (10) . A predetermined amount of the self-levelling, non-syntactic silicone foam composition, which may have started to foam upon dispensing, from dispensing head (8) , typically dependent on the volume of the housing. In Fig. 2 the housing (12) is observed to be partially filled with self-levelling, non-syntactic silicone foam composition. Once this action is completed the composition self-levels and then is allowed to continue foaming and curing until the resulting foamed material is prepared.

Fig. 3 is a photo of a series of batteries which have been surrounded by thermal insulation as described herein produced by curing and foaming the self-levelling, non-syntactic silicone foam composition. As previously indicated Figures 4a and 4b are two views of the thermal insulation resulting from curing and foaming the self-levelling, non-syntactic silicone foam composition. These clearly show that the insulation is continuous and has filled all voids between the cells.

The battery modules described herein are suitable for use in a wide variety of applications such as in electric-vehicle battery (EVB) power supplies for electric and hybrid (electric and petrol/diesel) powered vehicles, i.e. in battery packs/systems used to power the propulsion system of electric and hybrid vehicles and as such are designed to give power over sustained periods of time. As previously discussed, battery packs store the electricity used by the motor to drive a vehicle's wheels. In the case of hybrid type electric vehicles, the propulsion system is powered by a battery pack much like the above but a combustion engine is also present and as such hybrid vehicles run on electric power until the battery is depleted and then switch over to carbon based fuel which powers an internal combustion engine. These may include a battery pack wherein said self-levelling, non-syntactic silicone foam is used as thermal insulation disposed in said battery module housing to substantially fill voids between adjacent cells, particularly cylindrical cells. Typically, the battery module is used in a battery pack in a vehicle such as an all-electric road vehicle (EV) , a plug-in hybrid road vehicle (PHEV) , a hybrid road vehicle (HEV) or alternatively in other modes of transport such as an aircraft, a boat, a ship, a train.

The following examples, illustrating the compositions, foams, and methods, are intended to illustrate and not to limit the invention.

Compositions were generated utilizing different types and amounts of components. These are detailed below. All amounts are in wt. %unless indicated otherwise. As discussed above all viscosities are measured at 25℃. The viscosity of individual ingredients may be determined by any suitable method such as using a

rotational viscometer with spindle LV-1 (designed for viscosities in the range between 15 -20,000mPa. s) for viscosities less than 200mPa. s and adapting the speed according to the polymer viscosity. The alkenyl and/or alkynyl content of polymers as well as the silicon-bonded hydrogen (Si-H) content and/or silanol content of ingredients was determined using quantitative infra-red analysis in accordance with ASTM E168.

The following ingredients were used in the Examples:

Polymer 1: dimethylvinyl terminated polydimethylsiloxane having a viscosity of 350 mPa. s at 25℃;

Polymer 2: dimethylvinyl terminated polydimethylsiloxane having a viscosity of 12000 mPa. s at 25℃;

Hydromagnesite: a hydrated magnesium carbonate mineral having the formula Mg ₅ (CO ₃) ₄ (OH) ₂·4H ₂O having an average particle size of about 4μm, hydrophobically treated with a vinyl silazane; Aluminum trihydrate: chemical formula Al (OH) ₃

Glass Bubbles: the glass bubbles used in the comparative Example 1 (C. 1) were commercially available from the 3M Corporation as 3M ^TM Glass Bubbles S32HS;

Resin foam stabilizer: a ^ViMMQ resin, having a viscosity of ～45,000 mPa. s at 25℃ and ～0.39 wt. %vinyl;

Karstedt’s catalyst: a masterbatch of dimethylvinylsiloxy-terminated dimethyl siloxane and platinum complex. Platinum complex content is about 1.4%;

Fluorinated silicone polymer : a trimethyl terminated polydimethyl methyl perfluoropropyl siloxane having a viscosity of about 10,000 mPa. s at 25℃;

Fluorinated silicone resin (viscosity ～ 100 mPa. s at 25℃)

Physical Blowing Agent : 1, 1, 1, 3, 3-pentafluoropropane;

Organohydrogensiloxane: methylhydrogen siloxane, trimethylsiloxy-terminated, having a viscosity of about 20 mPa. s at 25℃ and about 1.6 wt. %SiH.

Three example compositions and two comparative compositions were prepared. Comparative 1 (C. 1) was a syntactic silicone composition. Ex. 1 was a chemically foamed composition; Ex. 2 was a physically foamed composition and Ex. 3 was a preferred physically foamed composition with all the resin foam stabilizer and catalyst in part A and all the filler and cross-linker in part B. The compositions used are depicted in Table 1a (part A) and Table 1b (part B) .

Table 1a: Part A compositions of Examples and Comparatives (wt. %)

Table 1b Part B compositions of Examples and Comparatives (wt. %)

The part A composition was prepared in an analogous fashion in each example/comparative, wherein the ingredients excepting the blowing agent were weighed into a Turello mixer container. They were then mixed using a Turello mixer (600 rpm, 20 min) . to form a homogeneous mixture. The mixture was then cooled to 5 ℃, and the blowing agent was introduced forming a homogeneous mixture.

Likewise, the part B composition was prepared in an analogous fashion in each example/comparative, all the ingredients were weighed into a Turello mixer container. They were then mixed using said Turello mixer (600 rpm, 20 min) to produce a homogeneous mixture If it is needed to add foam blowing agent, follow the same procedure as described in part A.

A series of physical tests were carried out using the compositions defined above with respect to the composition or the resulting foam. The viscosity measurements of the final composition after parts A and B had been mixed were carried out in accordance with ASTM D1084 using a Brookfield spindle LV-3 at 100rpm. Preferably the viscosity was less than or equal (≤) 2000m Pa. s at 25℃. Density measurements were undertaken in accordance with ASTM D792 using an AB204-SAnalytical Balance from Mettler Toledo. Preferably the density was less than 0.9 g/cm ³. Shore A hardness was determined in accordance with ASTM D 2240 using a hardness tester from Instron Type A Durometer with the sample sizes having a thickness of greater than (>) 6.5 mm. Preferably the Shore A hardness was greater than 20.

Samples underwent UL 94 testing. UL 94 is the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances testing in accordance with the Underwriters Laboratories of the United States. The standard determines the material’s tendency to either extinguish or spread the flame once the specimen has been ignited. The test was undertaken using an HVUL2 Horizontal Vertical Flame Chamber from Atlas with the sample test pieces had the following sizes: (125 ± 5) x (13.0 ± 0.5) x (2 ± 0.1) mm

Thermal insulation test Procedure and Conditions:

The thermal testing was undertaken on a test station comprising a heatable base plate with heat face dimension of 15cm x 17cm to provide heating temperature at about 600℃, an aluminum plate with dimension of 15cm x 17cm x 3cm, and a steel loading plate. The total weight of aluminum plate and steel loading plate was 19.2kg. Test specimens were prepared having the dimensions 8cm length, 8 4cm width and approximately 2mm thickness. The test specimen was mounted on the center of the aluminum plate, facing to heatable base plate with the surface area directly contacting with the heatable base plate was 0.0064m ². The steel loading plate was placed on the aluminum plate to make 0.03MPa pressure on the test specimen during testing. Two line notches in parallel, with depth as 0.45mm were cut on the specimen holding face of aluminum plate, starting from the long edge (17cm) , end with length of 7.5cm, distance between the two line notches was 4cm, evenly positioned near the center of aluminum plate. Two K-type jacketed thermocouples with O.D. as 0.5mm (WRNK-191, from Taizhou Cesmooy) were placed in the lined notches to measure the back temperature of test specimen. Polyimide tape was used to fix thermocouples and mount test specimen on aluminum plate.

The test lasted for 20min, with back temperature of specimen recorded. After the test, steel loading and Aluminum plate was removed from the heat stage.

Preferably the temperature of the back face was < 250℃ after 20 mins.

Electrical insulation measurements were undertaken in accordance with ASTM D 149 for dielectric strength using a 700-D149 Series -Dielectric Breakdown Tester for ASTM D149 from Hipotronics Inc. using a voltage increase speed 1 kV/s, sample size: 100 x 100 x 1mm. Volume resistance measurements were determined in accordance with ASTM D257 using a 4339B High Resistance Meter from Agilent Technologies and sample sizes of 100 x 100 x 1mm.

The physical property results are provided in Table 2.

Table 2: Physical property results

Compared with C. 1 (glass bubble filled silicone) , each of Ex. 1 to 3 showed excellent flowability and were able to self-level much better. The viscosities of Ex. 1-3 are all much lower i.e. between 800 and 1100 mPa. s at 25℃, which make the self-levelling as described herein easier to realize. The thermal insulation performance and flame retardancy are also significantly enhanced. C. 2 is a product developed for EV battery module potting with low viscosity (2000 mPa. s at 25℃) . Another advantage of the formulation in our invention is its high hardness. The hardness reached to 23 Shore A, while the hardness of C. 2 is only 11 Shore A.

Table 2b Physical property results

Claims

A process for thermally insulating adjacent battery cells in a battery module comprising the steps of:

(1) Taking a battery module comprising a housing with a lid in which is disposed a plurality of battery cells which are electrically connected but otherwise physically separated from each other;

(2) Dispensing a self-levelling, non-syntactic silicone foam composition into said housing, said self-levelling, non-syntactic silicone foam composition comprising the following components:

(i) one or more polydiorganosiloxanes having a viscosity of from 100 to 20,000 mPa.s at 25℃ having at least two unsaturated groups per molecule selected from alkenyl and/or alkynyl groups;

(ii) a platinum group metal, or a compound or complex of a platinum group metal;

(iii) a chemical blowing agent, a physical blowing agent or a mixture of a chemical blowing agent and a physical blowing agent;

(iv) one or more fire retardant fillers; and

(v) a cross-linker comprising an organosilicon compound having at least two, alternatively at least three silicon bonded hydrogen groups per molecule;

(3) Allowing the self-levelling, non-syntactic silicone foam composition to flow within the housing and self-level and as such fill voids between adjacent battery cells in said battery module; and

(4) enabling the self-levelling, non-syntactic silicone foam composition to foam, cure and consequently expand to fill the voids between adjacent battery cells during foaming and curing.
A process for thermally insulating adjacent battery cells in a battery module in accordance with claim 1 wherein the battery cells are cylindrical lithium ion battery cells.
A process for thermally insulating adjacent battery cells in a battery module in accordance with any preceding claim wherein the self-levelling, non-syntactic silicone foam composition has a viscosity of from 500 to 20,000 mPa.s at 25℃.
A process for thermally insulating adjacent battery cells in a battery module in accordance with any preceding claim wherein the composition is stored in two parts before use and the two parts are mixed before step (2) .
A process for thermally insulating adjacent battery cells in a battery module in accordance with any preceding claim wherein the self-levelling, non-syntactic silicone foam composition is stored in a part A composition and a part B composition prior to use wherein the part A composition comprises component (i) , component (ii) and component (iii) and the part B composition comprises component (i) , component (iv) and component (v) ;

such that components (ii) and (iii) are only in the part A composition and components (iv) and (v) are only in the part B composition.
A process for thermally insulating adjacent battery cells in a battery module in accordance with any preceding claim wherein component (iv) the one or more fire retardant fillers comprises hydromagnesite, which may optionally be hydrophobically treated.
A battery module having thermally insulating adjacent battery cells obtained or obtainable by following a process comprising the steps of

the steps of :

(1) Taking a battery module comprising a housing with a lid in which is disposed a plurality of battery cells which are electrically connected but otherwise physically separated from each other;

(2) Dispensing a self-levelling, non-syntactic silicone foam composition having a viscosity of from 500 mPa.s to 20,000 mPa.s at 25℃ into said housing, said self-levelling, non-syntactic silicone foam composition comprising the following components:

(i) one or more polydiorganosiloxanes having a viscosity of from 100 to 20,000 mPa.s at 25℃ having at least two unsaturated groups per molecule selected from alkenyl and/or alkynyl groups;

(ii) a platinum group metal, or a compound or complex of a platinum group metal;

(iii) a chemical blowing agent, a physical blowing agent or a mixture of a chemical blowing agent and a physical blowing agent;

(iv) one or more fire retardant fillers; and

(v) a cross-linker comprising an organosilicon compound having at least two, alternatively at least three silicon bonded hydrogen groups per molecule;

(3) Allowing the self-levelling, non-syntactic silicone foam composition to flow within the housing and self-level and as such fill voids between adjacent battery cells in said battery module; and

(4) enabling the self-levelling, non-syntactic silicone foam composition to foam, cure and consequently expand to fill the voids between adjacent battery cells during foaming and curing.
A battery module comprising a plurality of battery cells wherein voids between adjacent cells are filled with thermal insulation, which is the cured product of a self-levelling, non-syntactic silicone foam composition comprising the following components:

(i) one or more polydiorganosiloxanes having a viscosity of from 100 to 20,000 mPa.s at 25℃ having at least two unsaturated groups per molecule selected from alkenyl and/or alkynyl groups;

(ii) a platinum group metal, or a compound or complex of a platinum group metal;

(iii) a chemical blowing agent, a physical blowing agent or a mixture of a chemical blowing agent and a physical blowing agent;

(iv) one or more fire retardant fillers; and

(v) a cross-linker comprising an organosilicon compound having at least two, alternatively at least three silicon bonded hydrogen groups per molecule.
A battery module in accordance with claim 7 or 8 wherein the battery cells are cylindrical lithium-ion battery cells.
A battery module in accordance with claim 7, 8 or 9 which forms part of a battery pack of at least one battery module.
A battery module in accordance with claim 7, 8, 9 or 10 wherein the battery module is used in a battery pack in a vehicle.
A battery module in accordance with claim 11 wherein the vehicle is an all-electric road vehicle (EV) , a plug-in hybrid road vehicle (PHEV) , a hybrid road vehicle (HEV) or alternatively in other modes of transport such as an aircraft, a boat, a ship, a train.
Use of a self-levelling, non-syntactic silicone foam composition comprising the following components:

(i) one or more polydiorganosiloxanes having at least two unsaturated groups per molecule selected from alkenyl and/or alkynyl groups;

(ii) a platinum group metal, or a compound or complex of a platinum group metal;

(iii) a chemical blowing agent, a physical blowing agent or a mixture of a chemical blowing agent and a physical blowing agent;

(iv) one or more fire retardant fillers; and

(v) a cross-linker comprising an organosilicon compound having at least two, alternatively at least three silicon bonded hydrogen groups per molecule;

to provide a battery module having thermally insulated adjacent battery cells obtained or obtainable by following the process in accordance with any one of claims 1 to 6.
A two-part self-levelling, non-syntactic silicone foam composition comprising a part A composition of

(i) one or more polydiorganosiloxanes having a viscosity of from 100 to 20,000 mPa.s at 25℃ and at least two unsaturated groups per molecule selected from alkenyl and/or alkynyl groups; and

(ii) a catalyst comprising or consisting of a platinum group metal or a compound or complex thereof;

(iii) a chemical blowing agent, a physical blowing agent or a mixture of a chemical blowing agent and a physical blowing agent; and

a part B composition comprising

(i) one or more polydiorganosiloxanes having a viscosity of from 100 to 1000mPa.s at 25℃ having at least two unsaturated groups per molecule selected from alkenyl and/or alkynyl groups;

(iv) one or more fire retardant fillers;

(v) a cross-linker comprising an organosilicon compound having at least two, alternatively at least three silicon bonded hydrogen groups per molecule;

such that component (ii) is only in the part A composition and components (iv) and (v) are only in the part B composition.