Battery potting material with improved metal adhesion

Abstract

The invention relates to a battery module in which electrical units are encapsulated in an encapsulating material and the encapsulating material is obtained by mixing (a) one or more organic polyisocyanates, (b) one or more polymeric compounds having at least two isocyanate-reactive hydrogen atoms, (c) one or more organic polyisocyanates, (e) one or more organic polyisocyanates, (e) one or more organic polyisocyanates, and (e) one or more organic polyisocyanates. (c) 0.5% to 15% by weight, based on the total weight of components a) to f), of one or more chain extenders, (d) optionally one or more cross-linking agents, (e) one or more aromatic diamine curing agents, (f) one or more catalysts, (g) 2% to 20% by weight, based on the total weight of components a) to g), of one or more flame retardants, (h) at least one blowing agent and (i) optionally a filler and / or polyurethane additive to obtain a reaction mixture and curing the reaction mixture, the one or more chain extenders comprising an O-H-chain extender (c1) and an aromatic diamine hardener (c2). The invention also relates to a method for producing a battery module, in which the electrical units are encapsulated in an encapsulating material, and the encapsulating material is obtained by inserting a reaction mixture according to the invention into spaces between adjacent electrical units of a battery case in which the electrical units are arranged and curing the reaction mixture.

Description

[0001] The present invention relates to a battery module, wherein an electric cell is potted in a potting material and the potting material is obtained by mixing the following components: (a) one or more organic polyisocyanates, (b) one or more polymeric compounds having at least two isocyanate-reactive hydrogen atoms, (c) 0.5 wt % to 15 wt % of one or more chain extenders based on the total weight of components a) to f), (d) optionally one or more crosslinking agents, (e) one or more catalysts, (f) 2 wt % to 20 wt % of one or more flame retardants based on the total weight of components a) to f), (g) at least one blowing agent and (h) optionally fillers and / or polyurethane additives to obtain a reaction mixture and curing the reaction mixture, wherein the one or more chain extenders contain an OH-chain extender (c1) and an aromatic diamine curing agent (c2). The present invention also relates to a method for producing a battery module, wherein an electric cell is potted in a potting material, and the potting material is obtained by inserting the reaction mixture according to the present invention into the space between adjacent electric cells of a battery housing where the electric cells are arranged and curing the reaction mixture.

[0002] There is a very rapid transition from internal combustion engines to electric vehicles in the automotive industry. The design of the battery can be very different and is usually based on three types of battery cells: prismatic, pouch-shaped or cylindrical cells. In particular for the design of cylindrical cells from cells to packs, but not limited thereto, there are foams described in the literature that fill the cavities between the cells. The main purpose of the foam is thermal insulation to prevent chain reactions in the event of thermal runaway and fixation of the cells. In addition, the foam has the task of mechanically stabilizing the battery by stiffening it and minimizing vibrations.

[0003] For example, polyurethane-based potting foams are disclosed in US2012 / 0003508. The document discloses an energy storage device containing a foam, which may be a polyurethane foam containing a phosphate ester as a flame retardant

[0043] . The foam is described as being electrically insulating and showing a thermal conductivity between 0.02 W / mK and 1.0 W / mK. The function of the foam is to resist the propagation of fire to other generators of the battery by covering the side walls of the container of each generator with this foam. US2012 / 0003508 does not provide further details about the foam or its mechanical properties.

[0004] EP 3753056 discloses a battery module comprising a polyurethane-based potting compound having a density of less than 0.5 g / cm 3The foam is reactive and contains a liquid flame retardant and additives such as chain extenders. The electrical cells embedded in this foam are described as cylinders. After being fully cured, the potting compound can have a degree of elasticity, thereby cushioning shock or vibration imparted to the battery module. The encapsulation of the battery cells ensures an appropriate level of protection, such as an appropriate amount of structural stability and / or an appropriate amount of flame retardancy to help reduce the likelihood of an uncontrolled fire from the battery module.

[0005] WO2020 / 044744 solves the shrinkage problem of foams containing flame retardants. This shrinkage can cause battery deformation and gaps to form at the cells. The formation of this gap can reduce the fire spread properties. In order to prevent shrinkage, WO2020 / 044744 teaches the application of 20 to 150 parts by weight of polyols (based on 100 parts by weight of flame retardants) and the application of 25 to 75% by weight of flame retardants (based on the total mass of the potting material). The polyol contains 70 to 100 parts by weight of a polyol having a molecular weight of 2000 or more and preferably a polyol having a molecular weight of 200 or less.

[0006] CN109053993 discloses a protective material for a power battery using water as a foaming agent. In Example 1, a polyol component comprising a polyol, a catalyst, water and butanediol is mixed with an isocyanate component comprising MDI using a mixing ratio of 100:20. CN 109053993 does not disclose the addition of a flame retardant.

[0007] CN109251303 discloses a flame retardant heat insulating material based on water-foamed polyurethane for power batteries. The polyol and polyisocyanate components are mixed in a mixing ratio of 100:20 to 100:60.

[0008] CN111607351 discloses a potting material for a battery module, the potting material comprising an organic polyisocyanate, a polyether polyol, a chain extender, a flame retardant and a catalyst. CN111607351 does not disclose the addition of a blowing agent, and therefore does not disclose polyurethane.

[0009] It is known to exhibit very poor adhesion properties on metals, especially steel. The housing of the battery cell is often made of Made of base material. It is electroplated nickel diffusion annealed steel. Therefore, Surfaces are often those to which battery potting foams must adhere. The problem to be solved is to improve the adhesion of polyurethane foams to such surfaces to ensure better fixation of the foam to the cell and prevent gap formation. This increases the safety and life of the entire battery.

[0010] The object of the present invention is to improve the adhesion of polyurethane foam to metal surfaces, especially to steel or Another object of the present invention is to reduce the amount of flame retardant in the potting material while maintaining the fire spread resistance properties and to provide a foam having excellent properties in terms of adhesion to the cell, vibration damping and impact absorption.

[0011] The object of the present invention has been solved by a battery module, wherein an electric cell is potted in a potting material and the potting material is obtained by mixing the following components: (a) one or more organic polyisocyanates, (b) one or more polymeric compounds having at least two isocyanate-reactive hydrogen atoms, (c) 0.5 wt. % to 15 wt. % of one or more chain extenders, based on the total weight of components a) to f), (d) optionally one or more crosslinking agents, (e) one or more catalysts, (f) 2 wt. % to 20 wt. % of one or more flame retardants, based on the total weight of components a) to f), (g) at least one blowing agent and (h) optionally fillers and / or polyurethane additives to obtain a reaction mixture and curing the reaction mixture, the one or more chain extenders comprising an OH-chain extender (c1) and an aromatic diamine curing agent (c2). The present invention also relates to a method for producing a battery module, wherein an electric cell is potted in a potting material and the potting material is obtained by inserting the reaction mixture according to the present invention into the space between adjacent electric cells of a battery housing in which the electric cells are arranged and curing the reaction mixture.

[0012] The battery module according to the invention comprises several electrical cells. In a preferred method, the cells are cylindrical in shape. In a preferred embodiment, the outer surface of the cells is metal, preferably steel and particularly preferably -Steel. Such battery modules can be applied to a range of mobile devices and are particularly suitable for electric vehicles such as electric vehicles. The cells of the battery module according to the present invention are positioned in a potting material, and the potting material is a polyurethane foam. Such polyurethane foam is obtained by a method according to the present invention. The foam potting compound preferably has at least V2 flame retardancy, as measured by the UL 94 plastic flammability test. The battery cell is preferably surrounded by a battery shell. The battery shell can be configured to provide protection from moisture, heat, cold or any other potential factors that may cause damage to the electric cell. In a preferred embodiment, the shell includes a bottom, a top and a wall extending between the bottom and the top. The bottom can be the positive terminal of the electric cell or can be the negative terminal of the electric cell, depending on the desired orientation. The bottom of the electric cell is positioned in the potting compound. The potting compound occupies a portion of the internal volume of the battery shell and extends substantially equal distances from the bottom of the battery shell toward the top at various points along the wall. Typically, the top of the potting compound is lower than the top of the electric cell. Alternatively, the top of the electric cell may be lower than the top of the potting compound. The battery modules may be used to power many applications such as, but not limited to, household appliances, outdoor electrical equipment, or vehicles such as cars or boats.

[0013] The size of the gap between adjacent electrical cells and / or battery housings can be selected based on several variables, including but not limited to the size and / or weight of each electrical cell, the operating temperature of each electrical cell, the dimensions of each electrical cell, and the intended use of the battery module. In some examples, the size of the space between adjacent electrical cells can be from greater than 0 mm, about 0.25 mm, about 0.50 mm, about 0.75 mm to about 1.0 mm, about 1.5 mm, or about 2.0 mm, or a length between any pair of the foregoing values.

[0014] The hardness of the polyurethane foam as the potting material of the battery module is preferably 40 shore A to 60 shore D. Therefore, the damage to the battery caused by the stress when the resin is cured can be reduced, and the external impact on the battery pack can be properly absorbed. In addition, the potting material gives the entire battery module structure rigidity and stability.

[0015] The potting material is obtained by mixing the following components: (a) one or more organic polyisocyanates, (b) one or more polymeric compounds having at least two isocyanate-reactive hydrogen atoms, (c) 0.5 wt % to 15 wt % of one or more chain extenders based on the total weight of components a) to f), (d) optionally one or more crosslinking agents, (e) one or more catalysts, (f) 2 wt % to 20 wt % of one or more flame retardants based on the total weight of components a) to f), (g) at least one blowing agent and (h) optionally fillers and / or polyurethane additives to obtain a reaction mixture and curing the reaction mixture, wherein the one or more chain extenders include an OH-chain extender (c1) and an aromatic diamine curing agent (c2). The reaction mixture can flow through the gaps between adjacent electrical cells and settle at a level around the electrical cells and in the gaps or spaces defined between the electrical cells. For example, the reaction mixture can be poured into a battery housing where the electrical cells are arranged. The liquid reaction mixture has sufficient fluidity prior to solidification to allow the liquid potting composition to flow through spaces defined by gaps between adjacent electrical cells and / or between electrical cells and the battery housing and settle at a substantial level before its viscosity increases significantly due to the hardening process.

[0016] In a preferred embodiment, the potting material according to the invention has a g / dm 3 Up to 800g / dm 3 , more preferably 50g / dm 3 Up to 600g / dm 3 , even more preferably 100 g / dm 3 Up to 500g / dm 3 And particularly preferably 100 g / dm 3 Up to 300g / dm 3 density.

[0017] According to the present invention, the polyisocyanate component (a) for producing the polyurethane of the present invention comprises any polyisocyanate known for producing polyurethane. These polyisocyanates include aliphatic, alicyclic and aromatic difunctional or multifunctional isocyanates known from the prior art, as well as any desired mixtures thereof. Examples are diphenylmethane 2,2'-diisocyanate, 2,4'-diisocyanate and 4,4'-diisocyanate, mixtures of monomeric diphenylmethane diisocyanate and diphenylmethane diisocyanate homologues with a larger number of rings (polymer MDI), isophorone diisocyanate (IPDI) and oligomers thereof, toluene 2,4- and 2,6-diisocyanate (TDI) and mixtures thereof, tetramethylene diisocyanate and oligomers thereof, hexamethylene diisocyanate (HDI) and oligomers thereof, naphthylene diisocyanate (NDI) and mixtures thereof.

[0018] Preference is given to using toluene 2,4-diisocyanate and / or 2,6-diisocyanate (TDI) or mixtures thereof, monomeric diphenylmethane diisocyanate and / or diphenylmethane diisocyanate homologues (polymeric MDI) and mixtures thereof. Other possible isocyanates are described by way of example in the "Polyurethanes Handbook", 2nd edition, Carl Hanser Verlag, 1994, Chapters 3.2 and 3.3.2.

[0019] In a particularly preferred embodiment, polyisocyanate (a) comprises at least one isocyanate selected from the group consisting of monomeric MDI, polymeric MDI, prepolymers based on MDI or a mixture of at least two of these. At least 80% by weight, preferably at least 90% by weight and more preferably 100% by weight of isocyanate (a) consists of monomeric MDI, polymeric MDI, prepolymers based on MDI or a mixture of at least two of these.

[0020] The polyisocyanate component (a) used may be used in the form of a polyisocyanate prepolymer. These polyisocyanate prepolymers can be obtained by reacting an excess of the above-mentioned polyisocyanate (constituent (a-1)) with a polymeric compound (b) having a group reactive with isocyanate (constituent (a-2)) and / or with a chain extender (c) (constituent (a-3)) at a temperature of 30° C. to 100° C., preferably about 80° C. to obtain an isocyanate prepolymer.

[0021] Polymeric compounds (a-2) having groups reactive toward isocyanates are known to the person skilled in the art and are described by way of example in "Handbook of Polyurethanes", 2nd edition, Carl Hansel Verlag, 1994, Chapter 3.1: For example, it is also possible to use the polymeric compounds having groups reactive toward isocyanates described under (b) as polymeric compounds (a-2) having groups reactive toward isocyanates.

[0022] In a preferred embodiment, the content of monomeric MDI and polymeric MDI in component (a) is at least 35% by weight, more preferably 40% to 70% by weight, more preferably 41% to 60% by weight, and particularly preferably 42% to 48% by weight, based on the total weight of components (a) to (f). According to the present invention, the amount of monomeric MDI and polymeric MDI in component (a) includes monomeric and polymeric MDI (a-1) used for the production of polyisocyanate prepolymers, regardless of whether it is present as a separate molecule or as a reaction product with a polymeric compound (a-2).

[0023] As polymeric compound (b) having groups reactive toward isocyanate, any known compound having at least two hydrogen atoms reactive toward isocyanate may be used, for example those having a functionality of 2 to 8 and a number-average molar mass of 400 to 15 000 g / mol: for example, compounds selected from the group consisting of polyether polyols, polyols based on fatty acids, polyols based on polybutadiene, polyester polyols and mixtures thereof.

[0024] For example, polyether alcohols are generated from epoxides; for example, propylene oxide and / or ethylene oxide, or from tetrahydrofuran and a starting compound exhibiting hydrogen activity containing 1 to 8, preferably 2 to 6 reactive hydrogen atoms bound, or a starting molecule mixture containing 1.5 to 8, preferably 2 to 6 reactive hydrogen atoms bound in the presence of a catalyst. As starter molecules, for example, aliphatic alcohols, phenols, amines, carboxylic acids, water or compounds based on natural substances, such as sucrose, sorbitol or mannitol can be used. If a mixture of starting molecules with different functionalities is used, partial functionalities can be obtained. Influences on functionality, for example by side reactions, are not taken into account in the nominal functionality. Examples of suitable catalysts are basic catalysts or double metal cyanide catalysts, as described by way of example in PCT / EP2005 / 010124, EP90444 or WO 05 / 090440.

[0025] Polyester alcohols are prepared by way of example from aliphatic or aromatic dicarboxylic acids and polyols, polythioether polyols, polyesteramides, hydroxylated polyacetals and / or hydroxylated aliphatic polycarbonates, preferably in the presence of an esterification catalyst. Other possible polyols are mentioned by way of example in "Handbook of Polyurethanes, Vol. 7, Polyurethanes [Polyurethanes]", Karl Hansel Publishers, 2nd edition, 1993, Chapter 3.1.

[0026] In some embodiments, the present invention relates to polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention. The polyols for use in the present invention are polyols for use in the present invention.

[0027] In a particularly preferred embodiment of the present invention, component (b) comprises polyetherols and more preferably comprises no polyesterols.

[0028] Preferably, the polymeric compound (b) having groups reactive toward isocyanates comprises at least one polyether alcohol (b1) having a functionality of 2 to 4 and a hydroxyl number of 20 to 60 mg KOH / g. The polyether alcohol (b1) comprises preferably more than 50%, more preferably more than 70%, even more preferably more than 80% and particularly preferably more than 90% of primary hydroxyl groups, based on the total number of hydroxyl groups in the polyether (b1).

[0029] If a polymer polyol is used, the polymer polyol is applied in an amount of preferably 1 wt % to 30 wt %, more preferably 2 wt % to 20 wt %, even more preferably 3 wt % to 15 wt % and most preferably 4 wt % to 10 wt %, each based on the total weight of components (a) to (f).

[0030] The chain extender (c) used here can be a compound with a molar mass of less than 400 g / mol, preferably less than 300 g / mol, more preferably 62 g / mol to 250 g / mol, which has two groups reactive toward isocyanate, such as OH-, SH- or NH- 2 According to the invention, the chain extender (c) is used in an amount of 0.5% to 15% by weight, preferably 2% to 15% by weight, more preferably 3% to 15% by weight and particularly preferably 5% to 12% by weight, each based on the total weight of components a) to (f).

[0031] As chain extender (c), chain extenders known in polyurethane production can be used. Chain extender (c) comprises a compound (c1) having two OH groups (hereinafter referred to as OH-chain extender) and an aromatic diamine (c2) (hereinafter referred to as an aromatic diamine curing agent). In a preferred embodiment, the OH-chain extender (c1) can be selected from the group consisting of monoethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, tetraethylene glycol, dipropylene glycol, cyclohexanediol or a mixture thereof. In a more preferred embodiment, the OH-chain extender is selected from the group consisting of monoethylene glycol, diethylene glycol, dipropylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol or a mixture thereof. Other possible low molecular weight chain extenders are mentioned by way of example in "Polyurethane Handbook", 2nd edition, Carl Hansel Verlag, 1994, Chapters 3.2 and 3.3.2.

[0032] The aromatic diamine curing agent (c2) is selected from chain extenders based on radical aromatic amines, such as aromatic diamines, such as diethyltoluenediamine (DETDA). In a preferred embodiment, only OH-chain extenders (c1) and aromatic diamine curing agents (c2) are used as chain extenders (c). A preferred example of an aromatic diamine curing agent is DETDA. If used, the aromatic diamine curing agent (c2) is applied in an amount of preferably 0.5% to 4% by weight, preferably 1% to 3% by weight, each based on the total weight of compounds (a) to (f), provided that the total amount of chain extender (c) does not exceed 15% by weight, preferably 12% by weight, each based on the total weight of compounds (a) to (f). In a preferred embodiment, the ratio of OH-chain extender (c1) to aromatic diamine curing agent (c2) is between 200:1 and 1:1, preferably between 100:1 and 2:1 and particularly preferably between 50:1 and 3:1.

[0033] In addition to the chain extender (c), a crosslinker (d) can also be added to the mixture. As a chain extender, the crosslinker used in the present invention is a compound with a molar mass of less than 400 g / mol, preferably less than 300 g / mol and more preferably from 60 g / mol to 250 g / mol, which has at least three groups reactive toward isocyanates. Examples of crosslinkers are glycerol, trimethylolpropane, pentaerythritol and triethanolamine. Other possible low molecular weight crosslinkers are mentioned by way of example in "Handbook of Polyurethanes", Karl Hansel Verlag, 2nd edition, 1994, Chapters 3.2 and 3.3.2.

[0034] In a preferred embodiment of the present invention, in addition to the at least one chain extender (c), at least one crosslinker (d) is added to the mixture of the present invention. In a preferred embodiment, the mixture comprises 1% to 8% by weight, more preferably 2% to 5% by weight, of at least one crosslinker, based on the total weight of components a) to (f).

[0035] The catalyst (e) greatly accelerates the reaction of the polyol (b) and optionally the chain extender (c) and the crosslinker (d), and also the chemical blowing agent (e) with the polyisocyanate (a). As catalyst (e), any catalyst known in the field of polyurethane catalysts can be used. These catalysts include basic amine catalysts and metal-based catalysts. In a preferred embodiment, the catalyst includes an amine catalyst that can be incorporated. In a further preferred embodiment, the catalyst includes a delayed action catalyst. Delayed action catalysts are well known in the art and provide a long open time of the reaction mixture at room temperature and a fast cure at elevated temperatures.

[0036] The amine catalyst that can be incorporated has at least one, preferably 1 to 8 and particularly preferably 1 to 2 groups reactive to isocyanate, such as primary amine groups, secondary amine groups, hydroxyl groups, amide groups, or urea groups, preferably primary amine groups, secondary amine groups or hydroxyl groups. The amine catalyst that can be incorporated is mainly used to produce low-emission polyurethanes, especially for automotive interior parts. These catalysts are known and described in EP1888664 by way of example. These include compounds that preferably contain one or more tertiary amino groups in addition to groups reactive to isocyanate. Preferably, at least one tertiary amino group of the catalyst that can be incorporated carries at least two aliphatic hydrocarbon parts, preferably each part has 1 to 10 carbon atoms, particularly preferably each part has 1 to 6 carbon atoms. It is particularly preferred that the tertiary amino group carries two parts independently selected from methyl and ethyl parts, and carries another organic part. Examples of incorporable catalysts that may be used are bis-dimethylaminopropyl urea, bis(N,N-dimethylaminoethoxyethyl) carbamate, dimethylaminopropyl urea, N,N,N-trimethyl-N-hydroxyethyl bis(aminopropyl ether), N,N,N-trimethyl-N-hydroxyethyl bis(aminoethyl ether), diethylethanolamine, bis(N,N-dimethyl-3-aminopropyl)amine, dimethylaminopropylamine, 3-dimethylaminopropyl- N,N-dimethylpropane-1,3-diamine, dimethyl-2-(2-amino-ethoxyethanol) and (1,3-bis(dimethylamino)propan-2-ol), N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, bis(dimethylaminopropyl)-2-hydroxyethylamine, N,N,N-trimethyl-N-(3-aminopropyl)-bis(amino-ethyl ether), 3-dimethylaminoisopropyldiisopropanolamine, and mixtures thereof.

[0037] Examples of delayed action catalysts are carboxylates used with conventional basic amine catalysts. Carboxylates of basic amine catalysts are obtained here, for example, by mixing an amine catalyst with a carboxylic acid, optionally in the presence of an alcohol such as ethylene glycol. If an alcohol falls within the definition of chain extender (c) or crosslinker (d), this amount is taken into account when calculating the amount of crosslinker and chain extender in the reaction mixture.

[0038] Basic amine catalysts suitable for producing delayed action catalysts are described by way of example in the Polyurethane Handbook, Carl Hansel Publishers, 2nd edition 1994, Chapter 3.4.1. Examples of these include amidines such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, N,N,N',N'-tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)propene. Urea, N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane and preferably 1,4-diazabicyclo[2.2.2]octane, and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyldiethanolamine and N-ethyldiethanolamine, N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine and dimethylethanolamine. In particular, basic amine catalysts having at least one, preferably exactly one, group reactive toward isocyanate are used here, an example being N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine. The catalysts can be used individually or in the form of a mixture.

[0039] The carboxylic acids used are preferably those having a molar mass of less than 300 g / mol. Particular preference is given here to using saturated and unsaturated aliphatic monocarboxylic acids having 1 to 18 carbon atoms, for example formic acid, acetic acid, cyanoacetic acid or 2-ethylhexanoic acid; aromatic carboxylic acids; aliphatic, saturated and unsaturated dicarboxylic acids having 2 to 16 carbon atoms; or tricarboxylic acids; or mixtures thereof. Derivatives of the aforementioned carboxylic acids can also be used. Other preferred carboxylic acids used are of the general formula HOOC-(CH 2 ) n -COOH dicarboxylic acid, wherein n is an integer from 2 to 14. This type of dicarboxylic acid is generally less corrosive. Specifically, the carboxylic acid used includes adipic acid.

[0040] The ratio of acid to amine catalyst is selected here in such a way that the number of equivalents of the acid groups of the carboxylic acids contained is 0.5 to 1.5, preferably 0.7 to 1.3, particularly preferably 0.90 to 1.10 and in particular 0.95 to 1.05 equivalents, based on 1 equivalent of amine of the amine catalyst.

[0041] The carboxylate salt of the amine catalyst (c) may be used in a concentration of 0.001 to 10 wt %, preferably 0.05 to 5 wt % and particularly preferably 0.05 to 2 wt %, based on the weight of components (b) to (f).

[0042] Conventional non-incorporable amine catalysts may include amidines such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl- and N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutylenediamine, N,N,N',N'-tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane and preferably 1,4-diazabicyclo[2.2.2]octane, and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine and dimethylethanolamine.

[0043] Suitable metal-based catalysts include organometallic compounds, preferably organotin compounds, such as tin(II) salts of organic carboxylic acids, for example tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate and tin(II) laurate, and dialkyltin(IV) salts of organic carboxylic acids, for example dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate; and bismuth carboxylates, such as bismuth(III) neodecanoate, bismuth 2-ethylhexanoate and bismuth octoate; or mixtures thereof. The organometallic compounds can be used alone or preferably in combination with a strongly basic amine. In a particularly preferred embodiment, the catalyst (e) used comprises or consists of a delayed action catalyst and a particularly preferably incorporable delayed action catalyst.

[0044] If catalysts (e) are used, these can be used by way of example in concentrations of 0.001% to 5% by weight, in particular 0.05% to 2% by weight, based on the weight of component (b) as catalyst or respectively as catalyst combination.

[0045] As flame retardants (f), generally all flame retardants known from the prior art can be used. Suitable flame retardants are, for example, bromates, brominated ethers or brominated alcohols such as dibromoneopentyl alcohol, tribromo-neopentyl alcohol and 2-(2-hydroxyethoxy)ethyl 2-hydroxypropyl 3,4,5,6-tetrabromophthalate (PHT-4-diol TM), and chlorinated phosphates such as tris(2-chloroethyl)phosphate, tris(2-chloroisopropyl)phosphate (TCPP), tris(1,3-dichloropropyl)phosphate, tricresyl phosphate, 10-tris(2,3-dibromopropyl)phosphate, tetrakis(2-chloroethyl)ethylene diphosphate, dimethyl methanephosphonate, diethanolamine diethyl methylphosphonate and commercially available halogenated flame retardant polyols. As other phosphates or phosphonates, diethyl ethanephosphonate (DEEP), resorcinol bis(diphenyl phosphate) (RDP), triethyl phosphate (TEP), dimethyl propyl phosphate (DMPP), diphenyl cresyl phosphate (DPK) can be used as liquid flame retardants. In a preferred embodiment, the flame retardant comprises at least one group reactive to isocyanate such as a hydroxyl group (-OH) and / or a molecular weight of at least 350 g / mol.

[0046] In addition to the flame retardants already mentioned, inorganic or organic flame retardants such as red phosphorus, red phosphorus-containing additives, aluminum dioxide hydrate, antimony trioxide, arsenic oxide, ammonium polyphosphate and calcium sulfate, or cyanuric acid derivatives such as melamine, or a mixture of at least two of these flame retardants such as ammonium polyphosphate and melamine, and optionally corn or ammonium polyphosphate, melamine can be used as flame retardant (f) according to the present invention.

[0047] In a preferred embodiment of the present invention, the flame retardant (f) comprises at least one flame retardant which is liquid at room temperature. Particularly preferred are RDP, TCPP, TEP, DEEP, DMPP, DPK, PHT4 diol TM , brominated ethers and tribromo-neopentyl alcohol, especially TCPP, TEP and PHT4 diol TM And especially TCPP as liquid flame retardant. In a particularly preferred embodiment, flame retardant (c) comprises a phosphorus-containing flame retardant, and the phosphorus content is preferably 0.1 wt % to 3 wt %, more preferably 0.1 wt % to 1 wt % and particularly preferably 0.1 wt % to 0.5 wt %, based on the total weight of components (a) to (f). In a preferred embodiment, the flame retardant comprises a mixture of a liquid flame retardant and a solid flame retardant.

[0048] According to the invention, the proportion of flame retardant (f), based on the total weight of components (a) to (f), is 2% to 20% by weight, preferably 3% to 18% by weight, particularly preferably 4% to 16% by weight, and even more preferably 4% to 10% by weight, and particularly preferably 4% to 8% by weight.

[0049] As blowing agent (g), any blowing agent known in the polyurethane field can be used. These can include chemical and / or physical blowing agents. These blowing agents are described in the polyurethane handbook by way of example, Karl Hansel Publishing House, 2nd edition 1994, in chapter 3.4.5. The term chemical blowing agent here means a compound that forms a gaseous product by reacting with isocyanate. The examples of these blowing agents are water and carboxylic acid. The term physical blowing agent means a compound that is dissolved or emulsified in the starting material for the polyurethane production reaction and evaporates under polyurethane formation conditions. These are hydrocarbons, halogenated hydrocarbons, hydrogen halides and other compounds by way of example, and examples are perfluorinated alkanes, such as perfluorohexane, chlorofluorocarbons and ethers, esters, ketones, acetals and / or liquid carbon dioxide. Any desired amount of blowing agent can be used here. The amount of blowing agent preferably makes the density of the resulting polyurethane foam be 10g / L to 850g / L, particularly 20g / L to 800g / L, and especially 25g / L to 500g / L. Particular preference is given to using aqueous blowing agents, more preferably the blowing agent (g) consists of water.

[0050] In addition, fillers and / or polyurethane additives (h) may also be used. Any fillers and additives known for the production of polyurethanes may be used. Surfactants, foam stabilizers, cell regulators, stripping agents, inorganic and organic fillers, dyes, pigments, hydrolysis stabilizers, fungistatics and bacteriostatics may be mentioned by way of example. These substances are known and described by way of example in "Handbook of Polyurethanes", Karl Hansel Publishers, 2nd edition 1994, Chapters 3.4.4 and 3.4.6 to 3.4.11.

[0051] The amounts of polyisocyanate (a), the one or more polymers having at least two isocyanate-reactive hydrogen atoms (b), the one or more chain extenders (c), the one or more crosslinkers (d), the one or more catalysts (e), the one or more flame retardants (f), the at least one blowing agent (g) and the filler and / or polyurethane additive (h), if present, used in the production of the polyurethanes of the invention are generally such that the equivalent ratio of the NCO groups of the polyisocyanate (a) to the total number of reactive hydrogen atoms of components (b) to (h) is preferably from 0.75 to 1.5:1, more preferably from 0.80 to 1.2:1 and particularly preferably from 0.85 to 1.10. A ratio of 1:1 here corresponds to an isocyanate index of 100.

[0052] In order to produce a battery module according to the present invention, the reaction mixture according to the present invention can flow through the gaps between adjacent electrical cells and settle at a horizontal height around the electrical cells and settle in the gaps or spaces defined between the electrical cells. For example, the potting composition can be poured into the battery shell where the electrical cells are arranged. The liquid potting composition has sufficient fluidity before solidification to allow the liquid potting composition to flow through the space defined by the gaps between adjacent electrical cells and / or between the electrical cells and the battery shell. The liquid reaction mixture has sufficient fluidity to settle at a basic horizontal height before solidifying to form a potting material.

[0053] In a preferred embodiment, the electrical unit is cleaned, for example by plasma treatment, before being brought into contact with the reaction mixture according to the invention.

[0054] The potting material according to the present invention shows very good adhesion to metal surfaces such as steel and in particular to Hilumin. This reduces the unfavorable gap formation between the cells and the potting material, thereby improving flame retardancy, vibration damping and impact absorption. This allows the addition of smaller amounts of flame retardants while maintaining the flame retardant properties. On the other hand, smaller amounts of flame retardants improve the mechanical properties of the potting material. In addition, the electrical cells are thermally insulated from each other, and the potting material according to the present invention provides high impact absorption properties and high vibration damping. In addition, the potting material imparts structural rigidity and stability to the entire battery module. In addition, the heat generated during the production of the foam according to the present invention is lower so as to protect the individual battery cells from excessive thermal stress during the manufacturing process.

[0055] The present invention will be described below with reference to Examples. Example:

[0056] raw materials :

[0057] Polyol 1: Polyether alcohol with a number average molecular weight of 2000 g / mol, a functionality of 2, and an OH# of 55 mgKOH / G

[0058] Polyol 2: polyether triol with a number average molecular weight of 700 g / mol, a functionality of 3 and an OH# of 239 mgKOH / g based on glycerol and propylene oxide;

[0059] Polyol 3: Polyether alcohol based on TMP and propylene oxide with a functionality of 3 and an OH# of 860 mgKOH / g

[0060] Polyol 4: Polyether alcohol based on ethylenediamine and propylene oxide with a functionality of 4 and an OH# of 753 mgKOH / g

[0061] Crosslinker 1: Glycerol, 99.7% purity

[0062] Crosslinker 2: Triethanolamine: 85% triethanolamine and 15% monoethanolamine

[0063] Additive 1: 200, fumed silica from Evonik

[0064] Additive 2: Zinc stearate purchased from Sigma Aldrich

[0065] Additive 3: titanium dioxide, pigment, nucleating agent

[0066] Additive 4: DC5160: Foam cell surfactant from Dow Chemicals

[0067] Additive 5: 2,2,4-trimethyl-1,3-pentanediol diisobutyrate

[0068] Catalyst 1: Lupragen N 201, an amine catalyst from BASF

[0069] Chain extender 1: monoethylene glycol

[0070] Chain extender 2: diethylene glycol

[0071] Chain Extender 3: 1,4-Butanediol

[0072] Chain Extender 4: Diethyltoluenediamine (from Abermale 100)

[0073] Chain Extender 5: Dipropylene Glycol

[0074] Flame retardant (FR): TCPP: tris(2-chloroisopropyl) phosphate; flame retardant from ICL;

[0075] Water: tap water

[0076] Isocyanate: polymeric MDI with an average functionality of 2.7 and an NCO value of 31.5

[0077] According to the formulations given in Table 1 and Table 2, polyurethane foams were prepared and their adhesion properties were tested according to the following test procedure:

[0078] Determination of the adhesion of foam systems to steel surfaces

[0079] Preparation of samples:

[0080] Materials used :

[0081] - 0.5mm to 2mm thick metal coupons cleaned with isopropyl alcohol 25 x 100mm

[0082] - Foaming container with a diameter of 103mm and a height of 10mm

[0083] -Support with a diameter of 103mm and a height of 10mm

[0084] - Separation weight with dimensions of 60 x 20 x 150 mm in width x height x length and weighing 1300 g, wrapped in Teflon foil

[0085] - Heavy objects with dimensions of 40×20×150 mm in width×height×length and weighing 870 g

[0086] - Partition with dimensions of 30 x 0.5 x 40 mm in width x height x length

[0087] - Tractor Coesfeld

[0088] Setup for bonding foam systems to metal specimens

[0089] To test the adhesion of the foam system to metal surfaces, the metal coupons were thoroughly wetted on one side from below with the foaming foam system on the intended surface. Figure 2 As shown, the foaming container is placed on a flat surface with the opening facing upward, and a separation weight is placed from the edge of the foaming container toward the center. The metal sample is placed on a support with a spacer and locked with a weight. The free end of the metal sample is positioned to have an overlap length of 3.0 cm above the foaming container.

[0090] Sample generation

[0091] The foam system was freshly prepared in a beaker by providing the polyol component and adding the isocyanate component, followed by mixing with a Vollrath stirrer at 1920 rpm for 10 seconds. 23 g of the fresh foam system was then poured into a foaming container. The foaming container with the fresh foam system was provided with a separation weight, and a metal test piece was placed in a position above the foaming container with an overlap length of 30 mm with the foaming container. The fresh foam system began to rise and completely wet the metal specimen from below. Excess foam system rose onto the sides of the metal specimen without wetting the metal specimen from above. After the foaming system was cured, the separation weight was removed, and the composite material of the foaming container, the foaming system and the adhered metal specimen was stored for 2 days in a climate of 20°C and 50% relative humidity and then tested in a tensile test.

[0092] Tensile testing of foam systems and metal specimens

[0093] according to Figure 3Performing the tensile test The foaming container, the foam system and the composite material with the metal specimen adhered are clamped vertically into a pulling machine.

[0094] The metal specimen was then sheared from the foam system at an angle of 180° with a preload of 1 N and a tensile speed of 20 mm / min. The force generated was detected by a load cell. The maximum force of the tensile test was recorded and the average of three repeated tests was calculated for evaluation.

[0095] Cup foam test setup

[0096] The cup foam test of the mixed polyol and isocyanate components was carried out at ambient temperature. The polyol component was homogenized before use. A total of 260 g of the polyol and isocyanate mixture was added to a 1290 ml-PP cup in the order of the polyol followed by the isocyanate component. The stopwatch was started and the composition was mixed at 1920 rpm for 10 seconds. The reaction mixture was poured into a foaming beaker with a volume of 860 ml. After 10 minutes, the foam raised outside the beaker was cut with a knife without removing the upper part. After another 10 minutes, the upper part of the cup foam was removed to see if the foam core turned brown.

[0097] Table 1

[0098]

[0099]

[0100] Formulation C1 is a polyurethane foam disclosed in the prior art literature and can be used for encapsulating electrical units (equivalent to sample 1 of EP3753056B1). Adhesion on the substrate showed a low value of 73 N. Formulation C2 contained 1 wt% of chain extender in the polyol component. This directly resulted in The adhesion on the polyol component was increased as indicated by the value of 91N. For the case of higher amounts of chain extenders in the polyol component (formulations C3, C4 and C5), the values ​​obtained in the adhesion test were even higher and all were almost twice as high as the C1 value. Example C5 contained a mixture of two chain extenders and even for this case the adhesion test results were much higher when compared to the results of C1. Thus, it is shown that formulations containing at least one chain extender have an effect on the adhesion of the polyol component. Improved adhesion of the substrate, which is desirable for potting electrical cells.

[0101] C6 has the same polyol and isocyanate components as C4. The difference between C6 and C4 is the index. The index of C4 is 90.5 and the index of C6 is 100.5. This means that the isocyanate content is higher. Both examples show that the chain extender improves The effect of adhesion on the substrate is valid both for indices below and above 100, since the adhesion tests for C4 and C6 gave values ​​more than twice that obtained for C1.

[0102] This is also confirmed by the formulations C7 and C8 using different chain extenders. The polyol component of C7 contains 10 parts of chain extender. C7 was prepared with an index of 90.5 and the corresponding adhesion results are more than three times the adhesion results of C1. By using the same polyol component but increasing the index (as in the case of Example C8), the values ​​obtained in the adhesion test are still at a very high level.

[0103] Table 2

[0104]

[0105]

[0106] C9 is an example with 5 parts of aromatic diamine as chain extender. With this formulation, it was observed that after mixing it with the isocyanate component, the viscosity increased too quickly and it was not possible to perform the adhesion test with this formulation. By reducing the amount of diamine and combining it with an OH-terminated chain extender (E1), it was possible to perform the test and measure very high adhesion values ​​that were more than three times the adhesion value from Example C1. E1 shows that the combination of an OH-terminated chain extender with a small amount (<5 parts) of aromatic diamine can improve the adhesion of the Hi- Adhesion on substrate.

[0107] In E2 and C10, higher amounts of chain extender were applied. While in E2 with a chain extender concentration of 11.4 parts by weight, based on components a) to (f), a suitable foam with a white core was still obtained, for C10 with a chain extender concentration of 17.2 parts by weight, based on components a) to (f), a brown core was shown indicating a high center temperature of the foam, thereby indicating high temperatures during the foam formation. Temperature measurements within the foam showed that after a reaction time of 5 minutes, the core temperature in E2 was about 20°C lower than in the foam according to C10. Such high temperatures could potentially damage the electrical unit during potting.

Claims

1. A battery module, wherein the electric cells are potted in a potting material and the potting material is prepared by mixing the following components: a) one or more organic polyisocyanates, b) one or more polymeric compounds having at least two isocyanate-reactive hydrogen atoms c) 0.5 to 15 wt. %, based on the total weight of components a) to f), of one or more chain extenders, the chain extenders comprising an OH-chain extender (c1) and an aromatic diamine curing agent (c2), d) optionally one or more cross-linking agents e) one or more catalysts, f) 2 to 20 wt. %, based on the total weight of components a) to f), of one or more flame retardants, g) at least one blowing agent and h) optionally fillers and / or polyurethane additives The method comprises obtaining a reaction mixture and solidifying the reaction mixture. 2 . The battery module according to claim 1 , wherein the one or more polymeric compounds having at least two isocyanate-reactive hydrogen atoms (b) comprise a polyether alcohol (b1) having a functionality of 2 to 4 and a hydroxyl number of 20 to 60 mg KOH / g. 3 . The battery module according to claim 2 , wherein the polyether alcohol (b1) contains at least 80% of primary hydroxyl groups. 4 . The battery module according to claim 1 , wherein the organic polyisocyanate (a) comprises at least one isocyanate selected from the group consisting of monomeric MDI, polymeric MDI, prepolymers based on MDI, or a mixture of at least two of these. 5 . The battery module according to claim 1 , wherein the isocyanate index is 80 to 120.

6. The battery module according to any one of claims 1 to 5, wherein the content of monomeric MDI and polymeric MDI in component (a), including monomeric and polymeric MDI (a-1) for producing polyisocyanate prepolymers, is at least 35 wt %, based on the total weight of components (a) to (f).

7. The battery module according to any one of claims 1 to 6, wherein the OH-chain extender (c1) is selected from the group consisting of monoethylene glycol, diethylene glycol, dipropylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol or mixtures thereof. 8 . The battery module according to claim 1 , comprising 0.5% to 4% by weight of at least one aromatic diamine curing agent (c2). 9 . The battery module according to claim 8 , wherein the mass ratio between the OH-chain extender ( c1 ) and the aromatic diamine curing agent ( c2 ) is between 200:1 and 1:

1. 10 . The battery module according to claim 1 , wherein the flame retardant comprises a liquid flame retardant.

11. The battery module according to any one of claims 1 to 10, wherein the flame retardant comprises a phosphorus-based flame retardant and the content of phosphorus is 0.1 wt % to 1 wt % based on the total weight of the components (a) to (f), 12 . The battery module according to claim 1 , wherein the foaming agent contains water.

13. The battery module according to any one of claims 1 to 12, wherein the density of the potting material is 50 g / dm 3 With 600g / dm 3 between. 14 . The battery module according to claim 1 , wherein component b) comprises a polymer polyol. 15 . The battery module according to claim 1 , wherein the content of at least one polymer polyol is between 2% and 30% by weight, based on the total weight of compounds (a) to (f).

16. The battery module according to any one of claims 1 to 15, wherein component (e) comprises a delayed action catalyst.

17. A method for producing a battery module, the method comprising the steps of: providing a battery case having the electric cells arranged in defined spaces between adjacent electric cells, A reaction mixture is obtained by mixing the following components a) one or more organic polyisocyanates, b) one or more polymeric compounds having at least two isocyanate-reactive hydrogen atoms c) 0.5 to 15 wt. % of one or more chain extenders, based on the total weight of components (a) to (f), the chain extenders comprising an OH-chain extender (c1) and an aromatic diamine curing agent (c2) d) optionally one or more cross-linking agents e) one or more catalysts, f) 2 to 20 wt. %, based on the total weight of components a) to f), of one or more flame retardants, g) at least one blowing agent and h) optionally fillers and / or polyurethane additives as well as The reaction mixture is inserted into the space between the adjacent electrical cells and the reaction mixture is cured.

Images