Curable potting material for automobile battery pack

Abstract

The present invention relates to a two-component composition consisting of a first component and a second component; wherein the first component comprises:-at least one polyol having an average OH functionality of at least 2; -at least one first catalyst for catalyzing a reaction between a hydroxyl group and an isocyanate group; at least one second catalyst for catalyzing a trimerization reaction of isocyanate groups; -optionally, water; preferably, at least one foam stabilizer; and the second component comprises:-at least one oligomeric or polymeric polyisocyanate; preferably, at least one blowing agent; wherein the second catalyst is a trialkylphosphine compound; and wherein the molar ratio of all NCO groups in the two-component composition to all OH groups in the two-component composition is greater than 1.1, preferably greater than 1.3. The two-component composition is highly suitable as a potting material for producing structural battery packs using battery cells to vehicle body designs.

Description

Technical Field

[0001] The present invention relates to a two-component composition suitable as a potting material for producing battery packs; the use of such two-component composition as a potting material, in particular for manufacturing battery packs, especially for battery packs of electric vehicles; a method for producing battery packs; and a battery pack produced using this method. Background Art

[0002] Battery technology in electric vehicles is developing rapidly, and along with this, e-mobility has received significant attention in the past few years. In this regard, significant progress has been seen in the manufacturing of electric vehicle batteries in terms of economically viable and efficient production processes. Two trends in the current trends related to this application area are the cell-to-body design of battery packs (also known as structural battery packs) and the recently increasing adoption of cylindrical-shaped battery cells.

[0003] To reduce complexity and weight, the industry has moved from the cell-module-battery pack design to the cell-to-battery pack or cell-to-body design. That is, the battery cells are directly bonded to the battery pack, thus avoiding the need for an intermediate assembly of battery modules and all the associated inefficiencies in terms of the number of components, weight, cost, and complexity.

[0004] For example, the cell-to-battery pack design is implemented by bonding cylindrical battery cells to a cooling plate or cooling strip using a thermal interface material. This thermal interface material serves two purposes: first, it provides a mechanical fastening system to hold the battery cells in place; and second, it provides mechanical and thermal protection within the entire battery assembly. The mechanical and adhesive properties of such thermal interface materials are of crucial importance, and thus it should have the characteristics of a thermally conductive adhesive.

[0005] This assembly method using cylindrical battery cells also has a significant amount of free volume between the individual battery cells, which is therefore filled with an injectable or pourable material, most of which has a foamy honeycomb structure to reduce weight and provide shock-absorbing properties.

[0006] The function of this foam is to hold the battery cells in place during their service life and to thermally insulate the battery cells from each other. The latter is a safety function in the event of a battery cell failure: if one battery cell overheats uncontrollably (as is a risk associated with current lithium-based battery cells), then adjacent battery cells need to be protected from excessive temperatures, otherwise they will undergo thermal degradation and generate additional heat, even catch fire, potentially affecting other adjacent battery cells. Such a catastrophic event is called thermal runaway.

[0007] To reduce the overall vehicle weight, the material used to fill the interstitial volume is typically expanded into a foam.

[0008] The foams used in traditional cell-to-pack designs do not have significant mechanical functions and are typically soft to semi-rigid expanded two-component polyurethane (2C-PU) foams.

[0009] During the handling or manufacturing of the battery, such foams must cure with a limited exotherm to avoid damaging the cells, but they should also cure fast enough so as not to reduce the productivity of the battery assembly line.

[0010] Structural battery packs are an evolution of this concept. In this approach, the foam material has a much higher stiffness and mechanical strength than the foams in the traditional cell-to-pack designs just described. The stiffness of the cells in this approach beneficially helps to increase the mechanical and drive dynamics of the vehicle.

[0011] However, the foam material still needs to fulfill the above-described basic functions regarding thermal insulation. Additionally, to provide structural strength, the material needs to strongly connect all components of the battery pack (such as cells), and for this purpose, it needs to have good adhesion to a variety of materials. Furthermore, the material needs to have a high stiffness so that the battery pack contributes to the overall rigidity of the vehicle. High mechanical properties are also important for preventing physical damage to the cells in the case of a high-speed impact. It is also important to achieve the desired mechanical properties over the entire operating temperature range, typically from -20 °C to 65 °C. The glass transition of the material used should be outside this range, and the decrease in stiffness with increasing temperature needs to be as limited as possible. In the case of a thermal event, it is beneficial if the potting material can withstand high temperatures for an extended period with only limited degradation.

[0012] The implementation of such structural battery packs is typically achieved with 2C-PU materials having a high concentration of reactive groups, which provide the desired mechanical properties due to high crosslinking but, in turn, exacerbate the exothermic reaction during their curing and make temperature control during processing more challenging.

[0013] Furthermore, from a health and safety perspective, the hardener component of such highly functional 2C-PU systems typically exhibits a high content of monomeric isocyanates. To limit the exposure of workers and meet current workplace safety regulations (such as those implemented by European REACH), the manufacturing building requirements for ventilation and safety need to apply to the handling of such hazardous substances, which implies additional costs and complexity.

[0014] US20220209343A1 discloses, for example, such 2C-PU materials and a method of potting battery cells, thereby obtaining high mechanical stability and flame retardant properties. The 2C-PU material contains a liquid flame retardant additive and a blowing agent, and in an exemplary shown embodiment contains a curing component based on monomeric and / or polymeric MDI. While the mechanical and flame retardant properties of the cured material are indeed sufficient for the production of structural battery packs, care must be taken during production that the exothermicity of the cured material does not exceed a level that could damage the battery cells during assembly.

[0015] A common problem associated with such structural battery packs based on rigid, highly crosslinked polyurethane materials is the difficulty of easily removing or replacing individual battery cells after the material has been applied and partially cured. Once the crosslinking reaction of the 2C-PU material has proceeded sufficiently for the battery assembly to be movable within the assembly line, the battery cells are firmly embedded therein and cannot be removed or repositioned without significant effort and partial destruction of the potting material.

[0016] In addition, 2C-PU compositions generally require careful monitoring of the mixing ratio of the polyol and hardener components to obtain a suitable cured material with desired mechanical and other properties.

[0017] US2019 / 0233574 A1 discloses temperature-resistant polyisocyanurate foams produced from polyols, aliphatic polyisocyanates, blowing agents, foam stabilizers, and suitable catalysts. The catalysts taught for the trimerization of isocyanate groups are metal-organic compounds and salts, such as potassium 2-ethylhexanoate. However, the exothermicity during foaming using these catalysts makes the foams unsuitable for battery pack applications. In addition, the mechanical properties of these foams are not ideal for this purpose.

[0018] US2022 / 0127407 A1 discloses casting resins for electrical components and cables cured by isocyanate trimerization. The compositions disclosed in this document contain inorganic fillers and are not foams, but high-hardness casting resins. Therefore, they are not suitable for the production of structural battery packs.

[0019] Accordingly, there is still a need for a new and improved optionally foamed potting material suitable for the production of battery packs that overcomes the aforementioned drawbacks and provides new benefits. SUMMARY OF THE INVENTION

[0020] The object of the present invention is to provide a potting material highly suitable for use in the design and production of battery packs from battery cells to the body structure. To achieve high storage stability and rapid curing, the material should be provided in the form of a two-component composition that cures upon mixing of the components (preferably without external heating). The material should be rigid and mechanically strong enough after curing to provide the desired stability of the battery pack produced therefrom. In addition, it should have better EHS characteristics than commonly used 2C-PU materials, and in particular should have a low monomer isocyanate content. The material should cure with a very limited exothermicity to avoid thermal damage to the battery cells, and the curing should proceed in two steps: involving an initial gelation of the material to fix the battery cells in place, but still allowing disassembly and reuse of the battery cells in case of defects on the manufacturing line, followed by a slow final curing process lasting several hours or days to produce a highly rigid and strong material. In addition, a material is desired that cures into a highly rigid material even in the case of significant deviations (e.g., ±20% or higher) from the ideal weight or volume mixing ratio. In a preferred embodiment, the material should be foamable and have a freely adjustable foaming ratio (e.g., an expansion ratio of 0% to 1000%). Additionally, the cured material should exhibit a glass transition temperature (Tg) outside the thermal range relevant to electric vehicle batteries. Finally, the material should have high and durable thermomechanical stability in its cured state. Finally, the material should exhibit excellent electrical resistivity in its cured state to be suitable as a battery potting material.

[0021] Surprisingly, it has been found that all these objects can be achieved by the two-component composition according to independent claim 1.

[0022] In particular, in a first aspect, the present invention relates to a two-component composition consisting of a first component A and a second component B; wherein

[0023] - The first component A comprises:

[0024] - At least one polyol P having an average OH functionality of at least 2;

[0025] - At least one catalyst C1 for catalyzing the reaction between hydroxyl groups and isocyanate groups;

[0026] - At least one catalyst C2 for catalyzing the trimerization of isocyanate groups;

[0027] - Optionally, water;

[0028] - Preferably, at least one foam stabilizer F; and

[0029] - The second component B comprises:

[0030] - at least one oligomeric or polymeric polyisocyanate I;

[0031] - preferably, at least one blowing agent E;

[0032] wherein the catalyst C2 is a trialkylphosphine compound;

[0033] and wherein the molar ratio of all NCO groups to all OH groups in the two-component composition is greater than 1.1, preferably greater than 1.3.

[0034] Compared with the compositions used in the prior art for producing structural battery packs using battery cells into body designs, the two-component composition according to claim 1 unexpectedly provides significant advantages. More particularly, the composition according to claim 1 exhibits an exotherm limited to less than 80 °C during curing, thus significantly reducing the risk of damaging battery cells during battery pack production. In addition, the curing of the two-component composition according to claim 1 proceeds in two steps: initial gelation to fix the battery cells in place, but still allowing disassembly and reuse of the battery cells in case of defects on the manufacturing line, followed by slow curing over several days to obtain a highly rigid and structurally strong material. Moreover, compared with 2C-PU compositions, the composition according to claim 1 hardens into a highly rigid material even in the case of significant deviations (e.g., ±20% or higher) in the weight or volume mixing ratio of the two components. This can be achieved by the composition according to claim 1 or a unique dual-curing mechanism. In a preferred embodiment, the composition according to claim 1 is foamable and exhibits a freely adjustable expansion ratio of 0% to 1000%, providing the desired mechanical strength and stiffness even in a highly expanded state. Additionally, the composition according to claim 1 exhibits a Tg outside the operating range of electric vehicle batteries after curing and shows high thermomechanical stability. Finally, the composition according to claim 1 exhibits excellent resistivity in its cured state, which enhances its suitability as a potting material for batteries.

[0035] Accordingly, in a second aspect, the present invention relates to the use of the two-component composition according to the present invention as a potting material, particularly for manufacturing battery packs, especially for battery packs of electric vehicles, which is the subject of independent claim 10.

[0036] In a third aspect, the present invention relates to a method for producing a battery pack by using the two-component composition according to the present invention as a potting material, which is the subject of independent claim 12.

[0037] In a fourth aspect, the present invention relates to a battery pack produced by the method according to the present invention, which is the subject of independent claim 15.

[0038] Particularly preferred embodiments are set out throughout the description and the dependent claims.

[0039] Modes for carrying out the present invention

[0040] A first aspect of the present invention relates to a two-component composition consisting of a first component A and a second component B; wherein

[0041] - The first component A comprises:

[0042] - At least one polyol P having an average OH functionality of at least 2;

[0043] - At least one catalyst C1 for catalyzing the reaction between hydroxyl groups and isocyanate groups;

[0044] - At least one catalyst C2 for catalyzing the trimerization of isocyanate groups;

[0045] - Optionally, water;

[0046] - Preferably, at least one foam stabilizer F; and

[0047] - The second component B comprises:

[0048] - At least one oligomeric or polymeric polyisocyanate I;

[0049] - Preferably, at least one blowing agent E;

[0050] Wherein the catalyst C2 is a trialkylphosphine compound;

[0051] And wherein the molar ratio of all NCO groups to all OH groups in the two-component composition is greater than 1.1, preferably greater than 1.3.

[0052] In this document, the prefix "poly" in substance names such as "polyol", "polyisocyanate", "polyether" or "polyamine" indicates that the corresponding substance formally contains more than one functional group appearing in its name per molecule.

[0053] In this document, the term "polymer" firstly encompasses a collection of macromolecules that are chemically uniform but different in terms of degree of polymerization, molar mass and chain length, and the collection has been produced by a "poly" reaction (polymerization, polyaddition, polycondensation). Secondly, the term also encompasses derivatives of such collections of macromolecules from "poly" reactions, i.e., compounds of the following type: the compounds have been obtained by the reaction of functional groups on defined macromolecules (e.g., addition or substitution), and may be chemically uniform or chemically non-uniform. The term further encompasses so-called prepolymers, i.e., reactive oligomeric initial adducts whose functional groups participate in the formation of macromolecules.

[0054] The term "polyurethane polymer" encompasses all polymers produced according to the so-called diisocyanate polyaddition process. This also includes polymers that contain little or no urethane groups. Examples of polyurethane polymers are polyether polyurethanes, polyester polyurethanes, polyether polyureas, polyureas, polyester polyureas, polyisocyanurates, and polycarbodiimides.

[0055] In this document, "molecular weight" is understood to mean the molar mass (grams / mole) of a molecule or molecular residue. "Average molecular weight" means the number-average molecular weight Mn of a polydisperse mixture of oligomeric or polymeric molecules or molecular residues n , which is typically determined by gel permeation chromatography (GPC) using polystyrene as a standard.

[0056] In this document, "room temperature" means a temperature of 23 °C. Weight percentage values (abbreviated as % wt) refer to the mass ratio of the components in a composition based on the mass of the entire composition, unless otherwise stated. The terms "mass" and "weight" are used synonymously in this document.

[0057] "Primary hydroxyl group" means an OH group attached to a carbon atom having two hydrogens.

[0058] In this document, "pot life" means the processable time of a polyurethane composition after mixing two components, before the viscosity caused by the progress of the crosslinking reaction has become too high to allow further processing.

[0059] The term "strength" in this document refers to the strength of the cured composition, where strength particularly refers to the tensile strength and elastic modulus (especially in the elongation region of 0.05% to 0.25%), and / or the compressive strength and compressive modulus.

[0060] All industry standards and specifications mentioned in this document refer to the versions in effect at the date of first filing.

[0061] When a composition can be stored in a suitable container at room temperature for an extended period (typically at least 3 months up to 12 months or longer) without this storage causing any change in its application or use properties to an extent relevant to its use, the composition is referred to as "storage stable" or "storable".

[0062] "Open time" or "working time" means the period during which a composition can be processed or reprocessed after the curing process has started.

[0063] "Room temperature" means a temperature of 23 °C.

[0064] The first and second components of the composition are inherently storage stable and are stored in separate containers until they are mixed with each other shortly before or during application.

[0065] The two-component composition according to the invention consists of a first component A and a second component B.

[0066] First component A

[0067] The first component A of the two-component composition according to the invention comprises

[0068] - at least one polyol P having an average OH functionality of at least 2;

[0069] - at least one catalyst C1 for catalyzing the reaction between hydroxyl groups and isocyanate groups;

[0070] - at least one catalyst C2 for catalyzing the trimerization of isocyanate groups;

[0071] - optionally, water;

[0072] - preferably, at least one foam stabilizer F.

[0073] Polyol P

[0074] The first component A of the two-component composition according to the invention comprises at least one polyol P having an average OH functionality of at least 2.

[0075] Particularly suitable polyols P are those which are liquid at room temperature.

[0076] Preferably, the average molecular weight M n of the polyol P is 200 - 20,000 g / mol, preferably 250 - 10,000 g / mol, particularly 300 - 5,000 g / mol. If more than one type of polyol is used as polyol P, the average molecular weight M n refers to the average molecular weight M of all the polyols comprised in polyol P n .

[0077] Preferably, the average OH functionality of the polyol P is 2 - 4, more preferably 2.5 - 3. If more than one type of polyol is used as polyol P, the average OH functionality of the polyol P refers to the average OH functionality of all the polyols comprised in polyol P.

[0078] Particularly preferably, the average molecular weight M n of the polyol P is 250 - 10,000 g / mol, particularly 300 - 5,000 g / mol and the average OH functionality is 2 - 4, particularly 2.5 - 3.

[0079] Suitable polyols P as constituents of the first component A are in particular the following commercially available polyols or mixtures thereof:

[0080] - Polyether polyols, especially polyalkylene glycols and / or polyalkylene triols, especially polymerization products of ethylene oxide, 1,2 - propylene oxide, 1,2 - or 2,3 - butylene oxide, oxetane, tetrahydrofuran or mixtures thereof, where these substances are polymerized with the aid of starter molecules having two or more active hydrogen atoms, especially starter molecules such as water, ammonia or compounds having multiple OH or NH groups, for example ethane - 1,2 - diol, propane - 1,2 - or - 1,3 - diol, neopentyl glycol, diethylene glycol, triethylene glycol, isomeric dipropylene glycol or tripropylene glycol, isomeric butanediols, pentanediols, hexanediols, heptanediols, octanediols, nonanediols, decanediols, undecanediols, cyclohexane - 1,3 - or - 1,4 - dimethanol, bisphenol A, hydrogenated bisphenol A, 1,1,1 - trimethylolethane,

[0081] 1,1,1 - trimethylolpropane, glycerol, aniline, ethylenediamine or mixtures of the foregoing compounds. Also suitable are polyether polyols in which polymer particles are dispersed, especially those having styrene / acrylonitrile (SAN) particles or polyurea or polyhydrazodicarbonamide (PHD) particles.

[0082] Preferred polyether polyols are polypropylene glycols, polypropylene triols or ethylene oxide - capped (EO - capped) polypropylene glycols or triols. The latter are mixed polyoxyethylene / polyoxypropylene polyols (block copolymers), which are obtained especially by further alkoxylating polypropylene glycols or triols with ethylene oxide at the end of the propoxylation reaction and which as a result finally mainly have primary hydroxyl groups.

[0083] Preferred polyether polyols have an unsaturation of less than 0.02 meq / g, especially less than 0.01 meq / g.

[0084] - Polyester polyols, also known as low polyester alcohols, are prepared by known processes, in particular by the polycondensation of hydroxycarboxylic acids or lactones or by the polycondensation of aliphatic and / or aromatic polycarboxylic acids with diols or polyols. Polyester diols are preferably obtained by the reaction of diols (such as especially ethane-1,2-diol, diethylene glycol, propane-1,2-diol, dipropylene glycol, butane-1,4-diol, pentane-1,5-diol, 3-methylpentane-1,5-diol, hexane-1,6-diol, neopentyl glycol) or triols (such as glycerol, 1,1,1-trimethylolpropane) or mixtures of the above alcohols with organic dicarboxylic acids or their anhydrides or esters (such as especially succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid or hexahydrophthalic acid or mixtures of the above acids), or polyester polyols formed from lactones (such as especially ε-caprolactone). Polyester polyols formed from adipic acid or sebacic acid or dodecanedioic acid and hexanediol or neopentyl glycol are particularly preferred.

[0085] Particularly suitable polyester polyols are polyester diols.

[0086] - Polycarbonate polyols, which can be obtained, for example, by the reaction of the above-mentioned alcohols used to form polyester polyols with dialkyl carbonates, diaryl carbonates or phosgene.

[0087] - Block copolymers having at least two hydroxyl groups and at least two different blocks, the blocks having a polyether, polyester and / or polycarbonate structure of the type described above, especially polyether polyester polyols.

[0088] - Polyacrylate polyols and polymethacrylate polyols.

[0089] - Polyhydroxy-functional oils, also known as fatty acid polyols, especially natural oils optionally modified with ketone resins, especially castor oil or the reaction product of castor oil and a ketone resin; or polyols obtained by the chemical modification of natural oils (called oleochemical polyols), such as polyols obtained by the epoxidation of unsaturated oils and subsequent ring opening with carboxylic acids or alcohols, or polyols obtained by the hydroformylation and hydrogenation of unsaturated oils; or polyols obtained from natural oils by the following method: degradation processes, such as alcoholysis or ozonolysis, followed by chemical bonding of the degradation products or their derivatives obtained thereby, such as by transesterification or dimerization. Suitable degradation products of natural oils are especially fatty acids and fatty alcohols and fatty acid esters, especially methyl esters (FAME), which can be derived, for example, by hydroformylation and hydrogenation to hydroxy fatty acid esters.

[0090] - Polyhydrocarbon polyols, also known as oligohydrocarbon alcohols, such as polyhydroxy-functional polyolefins, polyisobutene, polyisoprene; polyhydroxy-functional ethylene / propylene, ethylene / butene or ethylene / propylene / diene copolymers (e.g., produced by Kraton Polymers); polyhydroxy-functional polymers of dienes (especially 1,3-butadiene), which can in particular also be prepared by anionic polymerization; polyhydroxy-functional copolymers of dienes (such as 1,3-butadiene) or diene mixtures with vinyl monomers (such as styrene, acrylonitrile, vinyl chloride, vinyl acetate, vinyl alcohol, isobutene and isoprene), such as polyhydroxy-functional acrylonitrile / butadiene copolymers, which can for example be prepared from epoxides or amino alcohols and carboxyl-terminated acrylonitrile / butadiene copolymers (commercially available, for example, under the name of CTBN or CTBNX or ETBN); and hydrogenated polyhydroxy-functional polymers or copolymers of dienes.

[0091] Particularly suitable polyols P are polyester polyols and polyether polyols, especially polyoxyethylene polyols, polyoxypropylene polyols, and polyoxypropylene polyoxyethylene polyols, preferably polyoxyethylene diols, polyoxypropylene diols, polyoxyethylene triols, polyoxypropylene triols, polyoxypropylene polyoxyethylene diols, and polyoxypropylene polyoxyethylene triols.

[0092] In a preferred embodiment, the polyol P consists of a mixture of diols and triols, said diols and triols being especially polyether diols and triols, preferably selected from the polyether diols and triols as just described above.

[0093] In another preferred embodiment, the polyol P consists of at least one triol, said at least one triol being especially at least one polyether triol, preferably selected from the polyether triols as just described above.

[0094] The first component A of the two-component composition preferably contains 50% to 99% by weight, especially 75% to 97% by weight, most preferably 85% to 95% by weight of polyol P, based on component A.

[0095] Catalyst C1

[0096] The first component A of the two-component composition according to the invention contains at least one catalyst C1 which catalyzes the reaction between hydroxyl groups and isocyanate groups.

[0097] Suitable as catalyst C1 are all known catalysts that accelerate the reaction of isocyanate groups with the hydroxyl groups of polyol P, in particular compounds of tin, iron, bismuth, zinc, manganese, chromium, cobalt, copper, nickel, molybdenum, lead, cadmium, mercury, antimony, vanadium, titanium, aluminum, potassium or rare earth metals, in particular organotin(IV) compounds such as dibutyltin diacetate, dibutyltin dilaurate, dimethyltin dilaurate, dibutyltin dichloride, dibutyldiacetylacetonatotin or dioctyltin dilaurate, bismuth(III) complexes, zinc(II) acetate, zinc(II) 2-ethylhexanoate, zinc(II) laurate, zinc(II) acetylacetonate, cobalt(II) 2-ethylhexanoate, copper(II) 2-ethylhexanoate, nickel(II) naphthenate, aluminum lactate, aluminum oleate, bis(ethyl acetoacetate)diisopropoxytitanium; compounds containing tertiary amino groups, in particular N-ethyldiisopropylamine, N,N,N’,N’-tetramethylalkylenediamine, pentamethylalkylenetriamine and its higher homologues, bis(N,N-diethylaminoethyl)adipate, tris(3-dimethylaminopropyl)amine, 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 2,2’-dimorpholinodiethylether (DMDEE), N-alkylmorpholine, N,N’-dimethylpiperazine; aromatic nitrogen compounds such as 4-dimethylaminopyridine, N-methylimidazole, N-vinylimidazole or 1,2-dimethylimidazole; organic ammonium compounds such as benzyltrimethylammonium hydroxide or alkoxylated tertiary amines; so-called “delayed action” catalysts, which are modifications of known metal or amine catalysts; and combinations of said compounds, in particular combinations of metal compounds and tertiary amines.

[0098] In a preferred embodiment of the two-component composition according to the invention, the catalyst C1 is an amine-based catalyst, preferably selected from the list 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 2,2’-dimorpholinodiethylether (DMDEE), and other catalytically active compounds containing tertiary amino groups. Most preferably, it is 1,4-diazabicyclo[2.2.2]octane (DABCO).

[0099] The first component A of the two-component composition preferably contains 0.1% to 5% by weight, in particular 0.5% to 4% by weight, most preferably 1% to 3% by weight of catalyst C1, based on component A.

[0100] Catalyst C2

[0101] The first component A of the two-component composition according to the invention comprises at least one catalyst C2 which is used for catalyzing the trimerization reaction of isocyanate groups, wherein the catalyst C2 is a trialkylphosphine compound.

[0102] Suitable as catalyst C2 are all trialkylphosphine compounds which show catalytic activity in the trimerization reaction of isocyanates.

[0103] It has been found that among all known trimerization catalysts only trialkylphosphines exhibit the properties required for the purposes of the present invention, in particular the low exothermicity desired during trimerization curing.

[0104] Particularly suitable as catalyst C2 are trialkylphosphine compounds having alkyl groups with 1 - 8 carbon atoms, in particular tributylphosphine and trioctylphosphine.

[0105] The most preferred catalyst C2 is trioctylphosphine.

[0106] Tri - octylphosphine has the molecular formula C 24 H 51 P and in particular means tri - n - octylphosphine or [CH3(CH2)7]3P.

[0107] When compared with other tertiary organophosphine catalysts (such as tri - n - butylphosphine), trioctylphosphine is considerably easier to handle and has significantly fewer problems with regard to environmental, health and safety performance (EHS). In particular, trioctylphosphine has far fewer problems with regard to generating unpleasant odors.

[0108] However, if desired, additional tertiary organophosphine catalysts may be present.

[0109] In any case, preferably, no other catalysts apart from trialkylphosphines are present in the composition.

[0110] Thus, in a very preferred embodiment of the two - component composition, the at least one trialkylphosphine catalyst consists of trioctylphosphine and no additional trimerization catalyst or trimerization co - catalyst apart from trioctylphosphine is added.

[0111] Tri - octylphosphine typically has sufficient solubility in the polyisocyanate composition in these proportions. Thus, trioctylphosphine can be used in pure form. However, it is also possible and preferably industrial - grade (≥90% purity) trioctylphosphine is used. Generally preferably, trioctylphosphine is liquid under ambient conditions and / or when it is added to the composition. Optionally, trioctylphosphine can be premixed and added with other substances (such as plasticizers, polyols, diluents or other additives).

[0112] However, optionally, trioctylphosphine and / or any other catalyst can also be dissolved in a suitable organic solvent for use to improve their compatibility. Suitable catalyst solvents are, for example, solvents that are inert to isocyanate groups and do not change the optical properties of the resulting composition, for example, by exhibiting poor compatibility and / or by exhibiting different densities.

[0113] The first component A of the two-component composition preferably contains from 0.1% by weight to 5% by weight, particularly from 0.5% by weight to 4% by weight, and most preferably from 1% by weight to 3% by weight of catalyst C2, based on component A.

[0114] Water

[0115] The first component A of the two-component composition according to the invention optionally contains water.

[0116] Water can be added as a blowing agent because it reacts with isocyanate groups to form CO2, which causes the composition to foam.

[0117] When water is added to component A, it is not necessary to add an additional blowing agent E to component B to achieve suitable foaming of the composition. It may be advantageous to ensure a sufficiently high isocyanate excess because some of the isocyanate groups react with water to form gaseous carbon dioxide.

[0118] Some preferred embodiments of the invention contain water in component A but do not contain an additional blowing agent E in component B.

[0119] Other preferred embodiments of the invention do not contain water in component A but contain an additional blowing agent E in component B.

[0120] Other preferred embodiments of the invention contain water in component A and at the same time contain an additional blowing agent E in component B.

[0121] The first component A of the two-component composition preferably contains from 0.1% by weight to 2.5% by weight, particularly from 0.25% by weight to 1.5% by weight, and most preferably from 0.5% by weight to 1% by weight of water, based on component A. In the same preferred embodiments, component B preferably does not contain any blowing agent E.

[0122] Foam stabilizer F

[0123] The first component A of the two-component composition according to the invention preferably contains at least one foam stabilizer F.

[0124] The foam stabilizer F can optionally but preferably be used to improve the foam quality in embodiments of a two-component composition that is intended to foam and contains a blowing agent E. When the curing of the composition has not progressed sufficiently to stabilize the formed foam solely by the cured polymer matrix, the foam stabilizer can help improve the foam quality and the cell structure of the formed foam at an early stage of the foaming process.

[0125] Therefore, preferably, when the two-component composition also contains a blowing agent E, the foam stabilizer F is included in the two-component composition.

[0126] Suitable as the foam stabilizer F are all known foam stabilizers commonly used in polyurethane foams. Preferred foam stabilizers F are silicone-based foam stabilizers, such as silicone-polyether copolymers.

[0127] Examples of suitable and preferred foam stabilizers are those available under the trade name series of Evonik such as B 8870, B 8491, B 8444, B 8460 and B 8523.

[0128] The first component A of the two-component composition preferably contains 0.5% to 7.5% by weight, particularly 1% to 6% by weight, and most preferably 2.5% to 5% by weight of the foam stabilizer F, based on component A.

[0129] The first component A of the two-component composition can contain additional optional additives, which will be discussed further below.

[0130] Second component B

[0131] The second component B of the two-component composition according to the invention contains

[0132] - at least one oligomeric or polymeric polyisocyanate I;

[0133] - preferably, at least one blowing agent E.

[0134] Polyisocyanate I

[0135] The second component B of the two-component composition according to the invention contains at least one oligomeric or polymeric polyisocyanate I.

[0136] "Oligomeric polyisocyanates" means polyisocyanates that have been obtained by reacting at least two monomeric polyisocyanates (in particular via dimerization and / or trimerization reactions of the isocyanate groups). This can form, for example, uretdione, isocyanurate, and / or biuret units. However, oligomeric polyisocyanates still have at least two free isocyanate groups per molecule. Methods for preparing oligomeric polyisocyanates are known to those skilled in the art. In addition, oligomeric polyisocyanates are commercially available from various suppliers, for example, in the form of hardener components for polyurethane coatings and adhesives. Suitable oligomeric polyisocyanates are commercially available, for example, in the product name series of Covestro N such as N 3600 or N 3300.

[0137] In a preferred embodiment, based on the weight of component B, the proportion of monomeric polyisocyanates (in particular diisocyanates) in polyisocyanate I is at most 1% by weight, in particular at most 0.5% by weight, preferably at most 0.3% by weight, in particular at most 0.2% by weight, more preferably at most 0.1% by weight, and most preferably less than 0.1% by weight.

[0138] In the same or other preferred embodiments, based on the total two-component composition, the total content of monomeric polyisocyanates (in particular diisocyanates) in the two-component composition is less than 0.5% by weight, preferably less than 0.4% by weight, more preferably less than 0.3% by weight, in particular less than 0.2% by weight, and most preferably less than 0.1% by weight.

[0139] Therefore, component B can contain at least one monomeric polyisocyanate (in particular diisocyanate), but the proportion should preferably be kept at a low level.

[0140] In practice, the removal of unwanted excess monomers can be achieved by distillation or extraction, preferably by thin-film distillation under high vacuum or by extraction with a suitable solvent inert to the isocyanate groups. Such methods are known to those skilled in the art.

[0141] Preferably, the at least one oligomeric polyisocyanate contained in polyisocyanate I has a uretdione, isocyanurate, urethane, biuret, imino diazinedione and / or diazinetrione structure. Particularly preferred are biuret, urethane, isocyanurate, and / or imino diazinedione structures. Especially preferred is the isocyanurate structure.

[0142] According to a preferred embodiment, based on the sum of all allophanate, isocyanurate, urethane, biuret, imino diazinedione and diazinetrione structures present in the polyisocyanate composition, the at least one polyisocyanate I contains isocyanurate structures to an extent of at least 50 mol%, preferably at least 60 mol%, more preferably at least 70 mol%, preferably at least 80 mol% or 90 mol%.

[0143] In particular, the at least one oligomeric or polymeric polyisocyanate I comprises an oligomeric polyisocyanate of one or more diisocyanate-based oligomers.

[0144] In particular, based on the weight of the polyisocyanate I, the at least one oligomeric or polymeric polyisocyanate I contains at least 70% by weight, in particular at least 80% by weight, especially at least 85% by weight, preferably at least 95% by weight, particularly preferably at least 98% by weight, for example at least 99% by weight of isocyanate groups having only aliphatic and / or cycloaliphatic bonding. In particular, the at least one oligomeric polyisocyanate has only aliphatic and / or cycloaliphatic-bonded isocyanate groups.

[0145] In particular, these oligomers are based on butane-1,4-diisocyanate, pentane-1,5-diisocyanate, hexane-1,6-diisocyanate, 2,2,4(or 2,4,4)-trimethylhexane-1,6-diisocyanate, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane or mixtures thereof. Particularly preferred are oligomers of 1,6-diisocyanatohexane.

[0146] In a highly preferred embodiment, the at least one oligomeric polyisocyanate I comprises or consists of: a trimer of 1,6-diisocyanatohexane, in particular hexamethylene triisocyanate triisocyanurate.

[0147] In another highly preferred embodiment, the at least one oligomeric polyisocyanate I comprises or consists of: a trimer of 1,5-diisocyanatopentane, in particular pentamethylene triisocyanate triisocyanurate.

[0148] In another highly preferred embodiment, the at least one oligomeric polyisocyanate I comprises or consists of: oligomers of diphenylmethane 4,4'-, 2,4'- and / or 2,2'-diisocyanate.

[0149] According to another particular embodiment, the polyisocyanate composition comprises a mixture of at least two oligomeric polyisocyanates, whereby the at least two oligomeric polyisocyanates are different in their chemical structure. In a particularly preferred embodiment thereof, the oligomeric or polymeric polyisocyanate I comprises both the isocyanurate of hexamethylene 1,6-diisocyanate (HDI) and polymeric diphenylmethane 4,4'-, 2,4'- and / or 2,2'-diisocyanate (PMDI).

[0150] Processes for preparing oligomeric polyisocyanates having a uretdione, isocyanurate, urethane, biuret, imino diazinedione and / or diazinetrione structure are described, for example, in the following documents: J. Prakt. Chem. 336 (1994) 185 - 200, DE 1 670 666, DE 1 954 093, DE 2 414 413, DE 2 452 532, DE 2641 380, DE 3 700 209, DE 3 900 053 and DE 3 928 503 or EP 0336 205, EP 0 339 396 and EP 0 798 299.

[0151] Suitable oligomers, polymers and derivatives suitable as oligomeric polyisocyanate I are in particular those derived from the following: diphenylmethane 4,4'-, 2,4'- and / or 2,2'-diisocyanate (MDI), toluene-2,4-diisocyanate (TDI), hexamethylene 1,6-diisocyanate (HDI), and 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane or isophorone diisocyanate (IPDI). Those derived from MDI and HDI are preferred.

[0152] Particularly suitable examples of commercially available oligomeric polyisocyanate I are in particular HDI biuret, such as N 100 and N 3200 (from Covestro), HDB and HDB-LV (from Vencorex) and 24A-100 (from Asahi Kasei); HDI isocyanurate, such as N3300, N 3600 and N 3790BA (all from Covestro), HDT, HDT-LV and HDT-LV2 (from Vencorex), TPA-100 and THA-100 (from Asahi Kasei) and HX (from Nippon Polyurethane); HDI uretidione, for example N 3400 (from Covestro); HDI imino diazinedione, for example XP 2410 (from Covestro); HDI urethane, for example VP LS2102 (from Covestro); IPDI isocyanurate, for example in solution form such as Z 4470 (from Covestro) or in solid form such as T1890 / 100 (from Evonik); TDI oligomer, for example IL (from Covestro); and TDI / HDI-based mixed isocyanurates, for example HL (from Covestro). Also particularly suitable are MDI forms that are liquid at room temperature (so-called "modified MDI"), which are mixtures of MDI with MDI derivatives (such as especially MDI carbodiimide or MDI uretonimines or MDI urethane), known under trade names such as CD, PF, PC (all from Covestro) or M 143 (from Dow), and mixtures of MDI with MDI homologues (polymeric MDI or PMDI), available under trade names such as VL, VL50, VL R10, VL R20, VH20N and VKS20F (all from Covestro), M 309, M 229 and M 580 (all from Dow) or M 10R (from BASF). The above oligomeric polyisocyanates are typically in practice mixtures of substances with different degrees of oligomerization and / or chemical structures. They preferably have an average NCO functionality of 2.1 to 4.0.

[0153] In a very preferred embodiment of the two-component composition, the oligomeric or polymeric polyisocyanate I comprises both the isocyanurate of hexamethylene 1,6-diisocyanate (HDI) and polymeric diphenylmethane 4,4'-, 2,4'- and / or 2,2'-diisocyanate (PMDI).

[0154] In the same or other preferred embodiments of the two-component composition, the oligomeric or polymeric polyisocyanate I comprises or consists of the following: a polyurethane polymer containing isocyanate groups.

[0155] Such an isocyanate-functional polymer is preferably pre-prepared by combining the at least one monomeric diisocyanate and the at least one polyol at a molar NCO / OH ratio of at least 1.1, in particular at least 1.3, preferably at least 1.5, more preferably at least 1.8, in the absence of moisture, at a temperature of 20 - 160 °C, preferably 40 - 140 °C, and optionally in the presence of a suitable catalyst. Such synthesis is well known in the art.

[0156] Suitable as polyols for this purpose are all the polyols further described above as polyol P, and the preferred embodiments of these polyols correspond to the preferred embodiments of polyol P.

[0157] Suitable as monomeric diisocyanates for this purpose are all monomeric diisocyanates, in particular diphenylmethane 4,4'-, 2,4'- and / or 2,2'-diisocyanate (MDI), toluene-2,4-diisocyanate (TDI), hexamethylene 1,6-diisocyanate (HDI) and 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane or isophorone diisocyanate (IPDI). Preferred are MDI and IPDI.

[0158] Particularly preferred isocyanate-functional polymers contained in polyisocyanate I have a monomeric diisocyanate content of less than 0.5% by weight, preferably less than 0.3% by weight, more preferably less than 0.2% by weight, most preferably less than 0.1% by weight, based on the total polymer. Such a low monomer isocyanate-functional polymer allows the curable composition to have a monomeric diisocyanate content of less than 0.1% by weight and is safe to use without special protective measures and without the need for hazard labeling.

[0159] For such polymers, the reaction preferably proceeds at a molar NCO / OH ratio of at least 3 / 1, preferably 3 / 1 to 10 / 1, in particular 3 / 1 to 8 / 1, and most of the remaining monomeric diisocyanate is then removed by a distillation method, preferably by thin-film distillation or short-path distillation under vacuum.

[0160] Another possibility of obtaining an isocyanate-functional polymer with a low monomeric diisocyanate content is by chemically reducing the content of monomeric diisocyanate, for example by adding a small amount of water, preferably in combination with a surfactant.

[0161] The second component B of the two-component composition preferably comprises from 50% to 100% by weight, in particular from 75% to 95% by weight, most preferably from 85% to 90% by weight, based on component B, of an oligomeric or polymeric polyisocyanate I.

[0162] Blowing agent E

[0163] The second component B of the two-component composition according to the invention preferably comprises at least one blowing agent E. The blowing agent E is only required when there is no water in component A. Thus, in all embodiments of the invention, it is possible to effect foaming by adding water to component A or by adding the blowing agent E to component B or by doing both simultaneously.

[0164] A "blowing agent" is an additive which, when activated, causes volume expansion in the two-component composition and ultimately leads to the formation of a foam material. The foam produced can be an open-cell foam or a closed-cell foam. The initial stabilization of the foam thus produced can be supported by a foam stabilizer F, but the ultimately produced foam and its cell structure are stabilized by the crosslinked or cured two-component composition.

[0165] Suitable blowing agents can be chemical blowing agents or physical blowing agents. Chemical blowing agents are organic or inorganic compounds which decompose under the influence of, for example, temperature or humidity, with at least one of the decomposition products formed being a gas. Physical blowing agents include, but are not limited to, compounds which become gaseous at a specific temperature or compounds which exhibit a significant increase in their vapour pressure upon moderate heating. Thus, both chemical and physical blowing agents are suitable for causing expansion in a thermally expandable composition, provided that their activation (whether by thermal activation or otherwise) is possible under the application conditions of the two-component composition according to the invention.

[0166] Suitable chemical blowing agents E include, for example, azo compounds, hydrazides, nitroso compounds, urethanes and carbohydrazides.

[0167] Also suitable as blowing agent E is a dual chemical system, such as an acid / base system which produces a gas upon reaction. An example is sodium bicarbonate and citric acid, a system which produces carbon dioxide when combined in a suitable medium.

[0168] Furthermore, especially in certain embodiments of two-component compositions which contain a large amount of highly reactive polyisocyanates (such as those based on MDI), it is possible to effect foaming by adding water to component A. After mixing components A and B, the water will react with some of the isocyanate groups to form gaseous CO2. Thus, water is also considered a blowing agent. However, water is preferably only present in component A and not in component B, since it may react prematurely with the polyisocyanate if present in the same component.

[0169] Suitable physical blowing agents include, for example, low-boiling hydrocarbons or halogenated hydrocarbons and expandable microspheres consisting of thermoplastic shells filled with a thermally expandable fluid or gas. Examples of such suitable microspheres are microspheres (from AkzoNobel).

[0170] In a preferred embodiment, the blowing agent E is a liquid at 23 °C.

[0171] Most preferably as blowing agent E are low-boiling hydrocarbons or halogenated hydrocarbons, especially such compounds that are liquids. Preferred and highly suitable examples of such preferred blowing agents E are LBA (from Honeywell), which is liquid trans-1-chloro-3,3,3-trifluoropropene.

[0172] Even more preferably, the blowing agent is water, which, however, should be included in component A. If water is present in component A, it is not necessary to further add blowing agent E in component B to achieve proper foaming of the composition.

[0173] The heat that may be required for the decomposition reaction that causes certain chemical blowing agents to foam (expand) or the heat required for the vaporization and volume expansion of physical blowing agents can be applied externally or internally, the latter, for example, from the exotherm of the curing reaction. In a preferred embodiment of this two-component composition, the heat of the limited exotherm generated by the curing material is sufficient for blowing agent E to cause the composition to foam. Such foaming should preferably occur in any case at a temperature below 100 °C, especially below 80 °C, preferably below 60 °C.

[0174] The second component B of this two-component composition preferably contains from 1% to 10% by weight, especially from 2.5% to 8% by weight, most preferably from 5% to 7.5% by weight of blowing agent E, based on component B.

[0175] Optional additive

[0176] As an optional ingredient of the first component A, this two-component composition may contain other substances reactive with isocyanates, especially

[0177] - difunctional or polyfunctional alcohols, especially those having an average molecular weight M of 250 - 500 g / mol n , especially ethoxylated and / or propoxylated bisphenol A, bisphenol F, trimethylolpropane or glycerol,

[0178] - chain extenders, especially diols having a molecular weight M of 62 - 150 g / mol n , especially ethylene glycol, propane-1,3-diol, butane-1,4-diol or pentane-1,5-diol,

[0179] - small amounts of polyamines, especially in order to directly obtain, when mixing the two components, a structurally viscous, firm and less fluid material,

[0180] - amino alcohols, or

[0181] - latent hardeners, such as especially ketimines, aldimines or oxazolines.

[0182] The two-component composition may additionally contain further ingredients in one or both of components A and B, especially the following auxiliaries and blends:

[0183] - fillers, especially ground or precipitated calcium carbonate (optionally coated with fatty acids, especially stearic acid), barite, quartz powder, quartz sand, dolomite, wollastonite, kaolin, calcined kaolin, sheet silicates such as mica or talc, zeolites, aluminium hydroxide, magnesium hydroxide, silica (including finely divided silica from a pyrolysis process), industrially produced carbon black, graphite, metal powders (such as powders of aluminium, copper, iron, silver or steel), PVC powder or hollow beads;

[0184] - fibres, especially glass fibres, carbon fibres, metal fibres, ceramic fibres, polymer fibres such as polyamide fibres or polyethylene fibres, or natural fibres such as wool, cellulose, hemp or sisal;

[0185] - nano-fillers, such as graphene or carbon nanotubes;

[0186] - dyes;

[0187] - pigments, especially titanium dioxide, chromium oxide, iron oxides or organic pigments;

[0188] - plasticisers, especially phthalates, terephthalates, trimellitates, adipates, sebacates, azelates, succinates, citrates, benzoates, diesters of o-cyclohexanedicarboxylic acid, acetylated glycerols, monoglycerides, fatty acid methyl or ethyl esters (also known as "biodiesel"), natural or modified vegetable oils, organic phosphates or sulfonates, sulfonamides, urethanes, high-boiling hydrocarbons, polybutenes, polyisobutenes, polystyrenes or chlorinated paraffins;

[0189] - solvents, especially those commonly used in paints, varnishes or coatings;

[0190] - modifiers, such as hydrocarbon resins, natural or synthetic waxes or bitumens;

[0191] - rheology modifiers, especially urea compounds, sheet silicates such as bentonite, castor oil derivatives, hydrogenated castor oil, polyamides, polyurethanes, pyrogenic silica or hydrophobically modified polyoxyethylene;

[0192] - Desiccants, especially molecular sieves, calcium oxide, mono oxazolidines such as 2 (from Incorez) or orthoformates;

[0193] - Adhesion promoters, especially titanates or organoalkoxysilanes such as aminosilanes, mercaptosilanes, epoxysilanes, vinylsilanes, (meth)acryloxysilanes, urethanesilanes, alkylsilanes, S-(alkylcarbonyl)mercaptosilanes, aldimine silanes or oligomeric forms of these silanes;

[0194] - Non-reactive thermoplastic polymers, e.g., homopolymers or copolymers of unsaturated monomers (especially from the group comprising ethylene, propylene, butene, isobutene, isoprene, vinyl acetate and alkyl (meth)acrylates), especially polyethylene (PE), polypropylene (PP), polyisobutene, ethylene-vinyl acetate copolymer (EVA) and random polyalpha-olefins (APAO);

[0195] - Flame retardant substances, especially the aluminum hydroxide or magnesium hydroxide fillers already mentioned, and also especially organophosphates, e.g., especially triethyl phosphate, tricresyl phosphate, triphenyl phosphate, diphenylcresyl phosphate, isodecyl diphenyl phosphate, tris(1,3-dichloro-2-propyl) phosphate, tris(2-chloroethyl) phosphate, tris(2-ethylhexyl) phosphate, tris(chloroisopropyl) phosphate, tris(chloropropyl) phosphate, isopropylated triphenyl phosphate, mono-, bis- or tris(isopropylphenyl) phosphates with different degrees of isopropylation, resorcinol bis(diphenyl phosphate), bisphenol A bis(diphenyl phosphate), ammonium polyphosphate, melamine or its derivatives, boron compounds or antimony compounds;

[0196] - Further additives, especially wetting agents, leveling agents, defoamers, degassing agents, stabilizers against oxidation, heat, light or UV radiation, or biocides;

[0197] And other substances commonly used in curable compositions.

[0198] Such additives can be present as components of the first component A or the second component B. Substances reactive with isocyanate groups are preferably components of the first component A. It may be advisable to chemically or physically dry certain components before mixing them into the corresponding components.

[0199] The mixing ratio of the first component A and the second component B of the two-component composition depends on the formulation of the individual components and can be customized to meet the requirements of the application process.

[0200] When formulating the two-component composition, it should be ensured that the amounts of polyol A and polyisocyanate I and / or the mixing ratio of components A and B are adjusted such that the molar ratio of all NCO groups to all OH groups in the two-component composition is higher than 1.1, particularly higher than 1.2, preferably higher than 1.3.

[0201] The reason for this excess of NCO groups compared to OH groups lies in the two-step curing mechanism described further below. The excess of NCO groups allows the trimerization of NCO groups after most or all of the OH groups from the polyol have been depleted due to the faster urethane formation reaction.

[0202] In a preferred embodiment of the two-component composition, the mixing ratio by weight parts between the first component A and the second component B is in the range of 5:1 to 1:5, particularly 1:1 to 1:3.

[0203] In the same or other preferred embodiments of the two-component composition, the mixing ratio by volume parts between the first component A and the second component B is in the range of 5:1 to 1:5, particularly 1:1 to 1:3.

[0204] The second aspect of the present invention relates to the use of the two-component composition (including all embodiments and preferred embodiments) as described above as a potting material, particularly for manufacturing battery packs (especially battery packs for electric vehicles).

[0205] The two-component composition (including all preferred embodiments for all possible components A and B) as described above is advantageously used as a potting material, particularly a potting foam material.

[0206] In a preferred embodiment of this use, the two-component composition (including all embodiments and preferred embodiments) as described above is used as a potting material, particularly a potting foam material, for manufacturing battery packs, especially battery packs for electric vehicles.

[0207] For the use as a potting material (particularly a potting foam material) for manufacturing battery packs (especially battery packs for electric vehicles), the two-component composition as described above has ideal properties beyond the prior art. In addition to curing performance and low exothermicity, it also shows excellent mechanical properties in the cured state, and it exhibits better EHS characteristics than the most commonly used 2C-PU potting materials.

[0208] The third aspect of the present invention relates to a method for producing a battery pack by using the two-component composition (including all embodiments and preferred embodiments) as described above as a potting material.

[0209] This method for producing a battery pack includes the following steps:

[0210] a) Mix the first component A and the second component B of the two-component composition as described above, including all embodiments and preferred embodiments,

[0211] b) Pour or inject the mixed composition into a battery pack assembly containing a plurality of battery cells such that any cavities or gaps between the battery cells are at least partially filled with the composition,

[0212] c) Cure the composition, wherein the first curing step c1 between the polyol and the polyisocyanate occurs spontaneously within minutes to hours, and the second curing step c2 involving isocyanate trimerization occurs spontaneously within hours to days or longer.

[0213] The curing step c1 occurs at room temperature catalyzed by the catalyst C1. The second curing step c2 catalyzed by the catalyst C2 takes longer and is accelerated by heat.

[0214] During or after the curing step c1, the battery cells embedded in the mixed and partially cured two-component composition can still be moved or replaced because the partially cured two-component composition has not yet reached the full rigidity and mechanical strength obtained after the second curing step c2.

[0215] Therefore, in a preferred embodiment of this method, at least one of the battery cells is moved or replaced during or after the first curing step c1.

[0216] The curing step c2 may take days or weeks to complete, yet this is not a problem. After the curing step c1, the material already has sufficient stability and strength such that the battery pack can be moved or even incorporated into, for example, an electric vehicle. The heat generated during the charging cycle of the battery (which can reach, for example, 60 °C during a fast charging cycle) will support and accelerate the curing step c2 and thus accelerate the final curing of the material. However, the curing step c2 can also be accelerated by placing the battery pack under slightly heated conditions for a short time, which should not exceed approximately 60 °C to 80 °C.

[0217] In a preferred embodiment of the above method, the two-component composition contains a blowing agent E and preferably contains a foam stabilizer F, and the volume expansion of the composition caused by the blowing agent E occurs before or concomitantly with the curing of the mixed two-component composition, which produces a foam with a closed-cell or open-cell structure.

[0218] The foamed material provides additional advantages such as weight reduction, thermal insulation, and shock absorption properties.

[0219] The fourth aspect of the present invention relates to a battery pack produced by the method of the present invention just described above.

[0220] Further advantageous embodiments of the invention can be seen from the exemplary embodiments. Detailed Description

[0221] Exemplary Embodiments

[0222] Material

[0223] For the experiments, the substances listed in Table 1 were used.

[0224] Table 1

[0225]

[0226]

[0227] Preparation of samples

[0228] The respective components A and B of the exemplary two-component compositions V-1 to V-5 were prepared separately by adding the respective ingredients shown in Tables 2 and 3 to the beaker of a speed mixer (SM) at room temperature. Then each component composition was flushed with N2 in the beaker and closed. Subsequently, the mixture was homogenized for 60 seconds using a speed mixer operating at 2500 rpm.

[0229] Table 2

[0230]

[0231] Table 3

[0232]

[0233] *Not according to the invention.

[0234] The total content of monomeric diisocyanate in component B of Examples V-1 and V-2 was 0.2% by weight based on component B.

[0235] For the curing and testing of the two-component compositions V-1 and V-2, both components A and B were mixed in a volume ratio of A:B of 1:2, which corresponds to a weight ratio of A:B of 1:2.1715.

[0236] After mixing at room temperature, curing started spontaneously, and the pot life (the time during which the material can be used to fill cavities) of Examples V-1 and V-2 was 1 minute. After 2 minutes of mixing components A and B, material V-1 started to foam.

[0237] Mechanical and thermal properties

[0238] Tensile strength, elongation at break and Young's modulus (at 0.05 - 0.25% elongation) were determined on sample V-2 according to DIN EN ISO 527 (tensile test speed: 2 mm / min) using a cured film with a thickness of 2 mm (Dogbone sample type 5A, DIN EN ISO 527-2).

[0239] The compression modulus was measured on fully cured and expanded sample V-1 according to ASTM D1621 (Compressive Properties of Rigid Cellular Plastics).

[0240] The electrical resistivity was measured on fully cured and expanded sample V-1 according to DIN EN 62631-3-1.

[0241] Dynamic mechanical analysis (DMA) measurements were carried out using an Anton Paar MCR 702e. The glass transition temperature (Tg) was determined by the phase angle tanδ, which corresponds to the ratio of the loss modulus to the storage modulus. The sample was heated from 20 °C to 150 °C at a heating rate of 5 °C min -1 The heating rate was 5 °C min. The frequency was kept constant at 1 Hz and the shear deformation was between 0.01% and 0.5%. The Tg value was determined for sample V-2 after curing at room temperature for 24 hours, and a second Tg value was determined after additional post-curing at 80 °C for 1 hour (which accelerated the trimerization curing step).

[0242] The expansion of the cured and expanded sample V-1 was measured as follows: First, the density of the cured samples V-1 and V-2 was determined using a pycnometer, and the percentage expansion of sample V-1 was calculated based on the density difference between the unexpanded sample V-2 and the expanded sample V-1.

[0243] These measurement results are shown in Table 4.

[0244] In Example Compositions V-3 to V-5, both Components A and B were mixed in a volume ratio of A:B of 1:1.8, which corresponds to a weight ratio of A:B of 1:1.5658. Each mixture of the two components in Examples V-3 and V-4 was poured into a mold (15 cm x 22 cm). Example V-5 reacted immediately in an uncontrollable manner during mixing, generating significant heat (>60 °C) and ultimately not producing a suitable homogeneous foam material. Therefore, it could not be used in the test protocol detailed below.

[0245] Samples V-3 and V-4 were measured according to the following protocol:

[0246] The maximum curing temperature in Samples V-3 and V-4 was measured using a Bosch UniversalTemp infrared laser thermometer. Temperature measurements were started immediately after the samples were mixed and poured into the mold. The surface temperature increase due to the exothermic reaction of the expanding mixture during pouring was monitored by repeated measurements until the temperature started to decline. The highest measured temperature was recorded as the maximum curing temperature.

[0247] The cream time measured for Samples V-3 and V-4 represents the time at which the foaming reaction starts after mixing. The timer was started immediately once the freshly mixed mixture was poured into the mold. Once the foam started to rise, the time was noted and represented as the cream time. The timer was kept running until the non-stick time (see below) was reached.

[0248] The rise time is the time it takes for the foam to reach its maximum expansion. The level of the rising foam in Samples V-3 and V-4 was marked on the mold with a pen. Once the rise was complete, the time was noted and represented as the rise time.

[0249] The non-stick time is defined as the time when the surface of the foam is no longer sticky. To measure the non-stick time, the surface of the foamed material was touched with a plastic straw. If the material left an imprint and stuck to the straw, the non-stick time had not been reached. If the material did not leave an imprint or stick to the straw, the non-stick time had been reached, and the corresponding time was noted.

[0250] The lap shear strength was measured according to EN 1465. The freshly mixed mixture of the two components in Experiments V-3 and V-4 was poured between two electrophoretically coated substrates (electrophoretically coated steel CG 800) with a 2 mm gap. The electrophoretically coated steel substrates were pre-cleaned with isopropanol. The material was then cured for 7 days (at 23 °C and 50% relative humidity). After 7 days, the substrates were pulled apart as defined in the standard test.

[0251] The tensile strength, elongation at break, and tensile modulus of Samples V-3 and V-4 were determined according to DIN ISO 1798. For the measurement, the freshly mixed mixture of the two components was poured into a mold (15 cm x 22 cm) and cured for 7 days (at 23 °C and 50% relative humidity). The specimens were then cut and pulled apart according to the standard DIN ISO 1798. The tensile modulus was measured between 0.05% and 0.25% elongation.

[0252] The compression modulus of Samples V-3 and V-4 was measured in the same way as for Sample V-1.

[0253] The results of these measurements are shown in Table 5.

[0254] Table 4

[0255] Measurement V-1 V-2 Tensile strength [MPa] n / m 48.2 Young's modulus (at an elongation of 0.05 - 0.25%) [MPa] n / m 2020 Tg (°C), after curing at room temperature for 24 hours 90 n / m Tg (°C), after post - curing at 60 °C for 1 hour 120 n / m Compression modulus [MPa] 95 n / m Resistivity [Ω·cm] <![CDATA[2.53·10 17 > n / m Swelling ratio [%] 200 n / m

[0256] "n / m" means that the value was not measured.

[0257] Table 5

[0258] Measurement V-3 V-4* Maximum curing temperature [°C] 46 50 Cream time [min] 4 3 Rise time [min] 10 8 Tack - free time [min] 12 30 Lap - shear strength [MPa] 0.99 0.81 Tensile strength [MPa] 1.17 1.04 Tensile modulus [MPa] 76.06 77.94 Elongation at break [%] 2.93 1.94 Compression modulus [MPa] 76.33 74.1

[0259] *Not according to the present invention.

[0260] The data given in Table 4 show that the compositions according to the invention exhibit very good mechanical properties and Tg values outside the operating temperature of an electric vehicle battery. In addition, the expanded embodiments show high volume expansion and very good compression moduli. Most notably, the excellent resistivity of the expanded sample V-1 exceeds that of the common 2C-PU compositions used in battery assemblies.

[0261] The data in Table 5 show that the foams of the invention using the catalyst defined in claim 1 have superior mechanical and curing properties compared to similar foams produced using prior art catalysts.

[0262] Those skilled in the art will understand that the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. Accordingly, the presently disclosed embodiments and implementations are to be considered in all respects as illustrative and not restrictive.

Claims

1. A two-component composition consisting of a first component A and a second component B; wherein - The first component A comprises: - At least one polyol P having an average OH functionality of at least 2; - At least one catalyst C1 for catalyzing the reaction between hydroxyl groups and isocyanate groups; - At least one catalyst C2 for catalyzing the trimerization of isocyanate groups; - Optionally, water; - Preferably, at least one foam stabilizer F; and - The second component B comprises: - At least one oligomeric or polymeric polyisocyanate I; - Preferably, at least one blowing agent E; wherein the catalyst C2 is a trialkylphosphine compound; and wherein the molar ratio of all NCO groups to all OH groups in the two-component composition is greater than 1.1, preferably greater than 1.

3.

2. The two-component composition according to claim 1, characterized in that, The catalyst C1 is an amine-based catalyst, preferably selected from 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 2,2'-dimorpholinodiethylether (DMDEE), and other catalytically active compounds containing tertiary amino groups.

3. The two-component composition according to any one of claims 1 and 2, characterized in that, The polyol P comprises at least one triol, especially a polyether triol, or a mixture of at least one triol and at least one diol, especially a mixture of a polyether triol and a polyether diol.

4. The two-component composition according to any one of the preceding claims, characterized in that, The catalyst C2 is trioctylphosphine.

5. The two-component composition according to claim 4, wherein The oligomeric or polymeric polyisocyanate I comprises both the isocyanurate of hexamethylene 1,6-diisocyanate (HDI) and polymeric diphenylmethane 4,4'-, 2,4'- and / or 2,2'-diisocyanate (PMDI).

6. The two-component composition according to any one of the preceding claims, characterized in that, The blowing agent E is a liquid at 23 °C.

7. The two-component composition according to any one of the preceding claims, characterized in that, The oligomeric or polymeric polyisocyanate I comprises a polyurethane polymer containing isocyanate groups.

8. The two-component composition according to any one of the preceding claims, characterized in that, The total content of monomeric diisocyanate is less than 0.5% by weight, especially less than 0.1% by weight, based on the total two-component composition.

9. A two-component composition according to any one of the preceding claims, characterized in that The mixing ratio by weight parts between the first component A and the second component B is from 5:1 to 1:5, especially from 1:1 to 1:

3.

10. Use of the two-component composition according to any one of the preceding claims as a potting material.

11. The use according to claim 10, characterized in that The potting material is used for manufacturing a battery pack, especially for a battery pack of an electric vehicle.

12. A method for producing a battery pack, comprising the following steps: a) Mixing the first component A and the second component B of the two-component composition according to any one of claims 1-9, b) Pouring or injecting the mixed composition into a battery pack assembly containing a plurality of battery cells such that any cavities or gaps between the battery cells are at least partially filled with the composition, c) Curing the composition, wherein a first curing step c1 between the polyol and the polyisocyanate occurs spontaneously within minutes to hours, and a second curing step c2 involving isocyanate trimerization occurs spontaneously within hours to days or longer.

13. The method according to claim 12, characterized in that, The two-component composition contains blowing agent E and preferably contains foam stabilizer F, and in which the volume expansion of the composition caused by blowing agent E occurs before or concomitantly with the curing of the mixed two-component composition, which produces a foam having a closed-cell or open-cell structure.

14. The method according to claim 12 or 13, characterized in that, Move or replace at least one of the battery cells during or after the first curing step c1.

15. A battery pack produced by the method according to any one of claims 12-14.

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