Battery potting material with improved adhesion to metals

Abstract

The present invention relates to a battery module in which electric cells are potted in a potting material, the potting material comprising: (a) one or more organic polyisocyanates; (b) one or more polymeric compounds having at least two isocyanate-reactive hydrogen atoms; (c) an OH chain extender (c1) and an aromatic diamine curing agent (c2); wherein the potting material is obtained by mixing 0.5 to 15 wt % of the 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 aromatic diamine curing agents, (f) one or more catalysts, (g) 2 to 20 wt % of one or more flame retardants, based on the total weight of components a) to g), (h) at least one blowing agent, and (i) optionally a filler and / or a polyurethane additive, to form a reaction mixture; and curing the reaction mixture. The present invention is further directed to a method for manufacturing a battery module, in which electric cells are potted in a potting material, the potting material being obtained by inserting a reaction mixture according to the present invention into spaces between adjacent electric cells of a battery case in which the electric cells are disposed, and curing the reaction mixture.

Description

[Technical Field]

[0001] The present invention relates to a battery module in which electric cells are potted in a potting material, the potting material being obtainable by mixing (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), including an OH chain extender (c1) and an aromatic diamine curing agent (c2), (d) optionally one or more crosslinking agents, (e) one or more catalysts, (f) 2 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 form a reaction mixture, and curing the reaction mixture. The present invention is further directed to a method for manufacturing a battery module, in which electric cells are potted in a potting material, the potting material being obtained by inserting a reaction mixture according to the present invention into spaces between adjacent electric cells of a battery case in which the electric cells are disposed, and curing the reaction mixture.

[0002] The automotive industry is experiencing a very rapid transition from internal combustion engines to electrified vehicles. Battery designs can vary widely and are typically based on three types of battery cells: prismatic, pouch, or cylindrical cells. Foams have been described in the literature to fill the voids between cells, particularly for cylindrical cell-to-pack designs, but this is not limited to this. The primary purpose of the foam is to provide insulation to prevent chain reactions in case of thermal runaway, and to secure the cells. Additionally, foams are responsible for mechanically stabilizing the battery by strengthening it and minimizing vibrations.

[0003] Polyurethane-based potting foams are disclosed, for example, in U.S. Patent Application Publication No. 2012 / 0003508. U.S. Patent Application Publication No. 2012 / 0003508 discloses an energy storage device containing a foam, which may be a polyurethane foam containing phosphate as a flame retardant.

[0043] The foam is described as being electrically insulating and exhibiting a thermal conductivity of 0.02 W / mK to 1.0 W / mK. The function of the foam is to prevent flame propagation to other generators in the battery by covering the sidewalls of each generator's container with the foam. U.S. Patent Application Publication No. 2012 / 0003508 does not provide further details about the foam or its mechanical properties.

[0004] European Patent No. 3753056 states that the density is 0.5 g / cm 3 A battery module is disclosed that includes a polyurethane-based potting compound that reacts with a foam having a density less than 1000 kJ / cm2 and contains additives such as a liquid flame retardant and a chain extender. The electric cells embedded in the foam are described as cylindrical. After fully cured, the potting compound may have a degree of elasticity, thereby cushioning shock or vibration transmitted to the battery module. Encapsulating the battery cells helps ensure an appropriate level of protection, such as an appropriate amount of structural stability and / or an appropriate amount of flame retardant, to reduce the likelihood of an uncontrolled flame erupting from the battery module.

[0005] WO 2020 / 044744 addresses the issue of shrinkage of foams containing flame retardants. This shrinkage leads to battery deformation and void formation in the cells. This void formation reduces fire spread prevention properties. To prevent shrinkage, WO 2020 / 044744 teaches applying 20 to 150 parts by weight of a polyol based on 100 parts by weight of the flame retardant, and applying 25 to 75 wt% of the flame retardant based on the total weight of the potting material. The polyol includes 70 to 100 parts by weight of a polyol having a molecular weight of 2000 or more, preferably a polyol having a molecular weight of 200 or less.

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

[0007] Chinese Patent Publication No. 109251303 discloses a flame-retardant thermal insulation material for power batteries based on water-blown polyurethane, in which the polyol and polyisocyanate components are mixed in a mixing ratio of 100:20 to 100:60.

[0008] CN111607351 discloses a potting material for battery modules, which comprises 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] Known materials exhibit very poor adhesive properties to metals, especially steel. Often, battery cell housings are made of Hilumin® substrates. Hilumin® is electro-nickel-plated, diffusion-annealed steel. Therefore, Hilumin® surfaces are often the surfaces to which battery potting foams must adhere. The problem to be solved is to increase the adhesion of polyurethane foams to these types of surfaces, ensuring better fixation of the foam to the cell and preventing gap formation. This increases the overall safety and lifespan of the battery.

[0010] The object of the present invention was to improve the adhesion of polyurethane foams to metal surfaces, particularly steel or Hilumin® surfaces, thereby increasing the overall battery life and safety. A further object of the present invention was to provide a foam with excellent properties in adhesion to the cell, vibration damping and shock absorption, while reducing the amount of flame retardant in the potting material while maintaining fire prevention properties.

[0011] The problem solved by the present invention is a battery module in which electric cells are potted in a potting material, the potting material being obtainable by mixing (a) one or more organic polyisocyanates, (b) one or more polymer 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), including an OH chain extender (c1) and an aromatic diamine curing agent (c2), (d) optionally one or more crosslinking agents, (e) one or more catalysts, (f) 2 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 a filler and / or a polyurethane additive, to produce a reaction mixture, and curing the reaction mixture. The present invention is further directed to a method for manufacturing a battery module, in which electric cells are potted in a potting material, the potting material being obtained by inserting a reaction mixture according to the present invention into spaces between adjacent electric cells of a battery case in which the electric cells are disposed, and curing the reaction mixture.

[0012] A battery module according to the present invention includes a plurality of electric cells. In a preferred embodiment, the cells are cylindrical. In a preferred embodiment, the outer surface of the cell is made of metal, preferably steel, and particularly preferably Hilumin® steel. Such a battery module can be applied to a range of mobile devices, particularly suitable for electric vehicles such as electric cars. The cells of the battery module according to the present invention are positioned within a potting material, which is polyurethane foam. Such polyurethane foam is obtainable by the method according to the present invention. The foam potting compound preferably has a flame retardancy of at least V2 level as measured by the UL94 test for flammability of plastics. The battery cells are preferably surrounded by a battery case. The battery case may be configured to provide protection from moisture, heat, cold, or other potential factors that may damage the electric cells. In a preferred embodiment, the case includes a bottom, a top, and a wall extending between the bottom and top. The bottom may be the positive or negative terminal of the electric cell, depending on the desired orientation. The bottoms of the electric cells are positioned within a potting compound. The potting compound occupies a portion of the interior volume of the battery case and extends substantially equal distances at various points along the wall from the bottom to the top of the battery case. Typically, the tops of the potting compound are lower than the tops of the electric cells. Alternatively, the tops of the electric cells may be lower than the tops of the potting compound. The battery module can be used to power many applications, such as, but not limited to, household appliances, outdoor electrical equipment, or vehicles such as automobiles or boats.

[0013] The size of the gap between adjacent electric cells and / or battery cases can be selected based on several variables, including, but not limited to, the size and / or weight of each electric cell, the operating temperature of each electric cell, the dimensions of each electric cell, and the intended use of the battery module. In some examples, the size of the space between adjacent electric cells can be greater than 0 mm, about 0.25 mm, about 0.50 mm, about 0.75 mm, 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 urethane foam used as a potting material for a battery module is preferably 40 Shore A to 60 Shore D. As a result, damage to the battery caused by stress during resin curing can be reduced, and external impacts received by the battery pack can be adequately absorbed. Furthermore, the potting material provides structural rigidity and stability to the entire battery module.

[0015] The potting material can be obtained by mixing (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, including OH chain extenders (c1) and aromatic diamine curing agents (c2), based on the total weight of components a) to f), (d) optionally one or more crosslinking agents, (e) one or more catalysts, (f) 2 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 form a reaction mixture and curing the reaction mixture. The reaction mixture can flow through the gaps between adjacent electric cells and settle horizontally around the electric cells and in the gaps or spaces defined between the electric cells. For example, the reaction mixture can be poured into a battery case with the electric cells disposed therein. The liquid reaction mixture has sufficient fluidity before curing to allow the liquid potting composition to flow through the spaces defined by the gaps between adjacent electrical cells and / or the gaps between the electrical cells and the battery case and settle to a substantially horizontal height before its viscosity is significantly increased by the curing process.

[0016] In a preferred embodiment, the potting material according to the present invention has a viscosity of 20 to 800 g / dm 3 , more preferably 50 to 600 g / dm 3 , and even more preferably 100 to 500 g / dm 3 , particularly preferably 100 to 300 g / dm 3 It has a density of

[0017] According to the present invention, the polyisocyanate component (a) used to prepare the polyurethanes of the present invention may be any of the polyisocyanates known for the production of polyurethanes. These include aliphatic, cycloaliphatic, and aromatic di- or polyfunctional isocyanates known from the prior art, as well as any desired mixtures thereof. Examples include diphenylmethane 2,2'-, 2,4'-, and 4,4'-diisocyanate, mixtures of monomeric diphenylmethane diisocyanate with diphenylmethane diisocyanate homologues with a higher number of rings (polymeric MDI), isophorone diisocyanate (IPDI) and its oligomers, tolylene 2,4- and 2,6-diisocyanate (TDI) and mixtures thereof, tetramethylene diisocyanate and its oligomers, hexamethylene diisocyanate (HDI) and its oligomers, naphthylene diisocyanate (NDI), and mixtures thereof.

[0018] Preferably, tolylene 2,4- and / or 2,6-diisocyanate (TDI) or mixtures thereof, monomeric diphenylmethane diisocyanate and / or diphenylmethane diisocyanate homologues (polymeric MDI), and mixtures thereof are used. Other possible isocyanates are described, for example, in "Polyurethanes Handbook", Carl Hanser Verlag, 2004, Vol. 1, No. 1, pp. 117-122, 1997. nd edition 1994, chapters 3.2 and 3.3.2.

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

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

[0021] Polymer compounds (a-2) having groups reactive with isocyanates are known to those skilled in the art and are described, for example, in "Polyurethanes Handbook", Carl Hanser Verlag, 2002. nd Edition 1994, Chapter 3.1: For example, as the polymer compound (a-2) having a group reactive with isocyanate, it is also possible to use the polymer compound described in (b) having a group reactive with isocyanate.

[0022] In a preferred embodiment, the content of monomeric 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 and polymeric MDI in component (a) includes the monomeric and polymeric MDI (a-1) used in the preparation of the polyisocyanate prepolymer, whether this is present as individual molecules or as a reaction product with polymeric compound (a-2).

[0023] As polymeric compound (b) having groups reactive towards isocyanates, it is possible to use any of the known compounds having at least two hydrogen atoms reactive towards isocyanates, for example those having a functionality of 2 to 8 and a number average molecular weight of 400 to 15,000 g / mol: for example, compounds selected from the group consisting of polyether polyols, fatty acid-based polyols, polybutadiene-based polyols, polyester polyols, and mixtures thereof.

[0024] Polyetherols are prepared, for example, from epoxides, such as propylene oxide and / or ethylene oxide, or from tetrahydrofuran with hydrogen-active starter compounds containing 1 to 8, preferably 2 to 6, bound reactive hydrogen atoms, or from mixtures of starter molecules containing 1.5 to 8, preferably 2 to 6, bound reactive hydrogen atoms in the presence of a catalyst. Examples of starter molecules include aliphatic alcohols, phenols, amines, carboxylic acids, water, or compounds based on natural substances, such as sucrose, sorbitol, or mannitol. When using a mixture of starter molecules with different functionalities, fractional functionalities may be obtained. The contribution of side reactions to functionality is not taken into account in the nominal functionality. Examples of suitable catalysts include basic catalysts and double-metal cyanide catalysts, as described, for example, in PCT / EP2005 / 010124, EP 90444, or WO 05 / 090440.

[0025] Polyesterols are prepared, for example, from aliphatic or aromatic dicarboxylic acids and polyhydric alcohols, polythioether polyols, polyesteramides, hydroxylated polyacetals, and / or hydroxylated aliphatic polycarbonates, preferably in the presence of an esterification catalyst. Other possible polyols are described, for example, in "Polyurethanes Handbook," volume 7, "Polyurethanes," Carl Hanser Verlag, 2004.nd Edition 1993, chapter 3.1.

[0026] Other materials that can be used in conjunction with the described polyetherols and / or polyesterols are filled polyols, such as polymer polyols, such as polymer polyetherols or polymer polyesterols. These compounds preferably contain dispersed particles made from thermoplastic resins composed of olefin monomers, such as acrylonitrile, styrene, (meth)acrylates, (meth)acrylic acid, and / or acrylamide. These polyols containing fillers are known and commercially available. Manufacturing processes for these polyols are described, for example, in DE-A-111394, U.S. Pat. No. 3,304,273, U.S. Pat. No. 3,383,351, U.S. Pat. No. 3,523,093, DE-A-1152536, DE-A-1152537, WO-A-2008 / 055952, and WO-A-2009 / 128279.

[0027] In a particularly preferred embodiment of the present invention, component (b) comprises a polyetherol, more preferably does not comprise a polyesterol.

[0028] Preferably, the polymeric compound (b) having isocyanate-reactive groups comprises at least one polyetherol (b1) having a functionality of 2 to 4 and a hydroxyl number of 20 to 60 mg KOH / g. The polyetherol (b1) preferably contains 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 polyetherol (b1).

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

[0030] The chain extender (c) used here may be a compound having two isocyanate-reactive groups, such as OH, SH or NH groups, and having a molar mass of less than 400 g / mol, preferably less than 300 g / mol, more preferably 62 to 250 g / mol. According to the invention, the chain extender 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, particularly preferably 5 to 12% by weight, based on the total weight of components a) to (f), respectively.

[0031] The chain extender (c) can be any chain extender known in the production of polyurethanes. The chain extender (c) includes a compound (c1) having two OH groups (hereinafter referred to as the OH chain extender) and an aromatic diamine (c2) (hereinafter referred to as the 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-propanediol, 1,3-propanediol, 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-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, or a mixture thereof. Other possible low molecular weight chain extenders are described, for example, in ''Polyurethan Handbook'', Carl Hanser Verlag, 2002. nd edition 1994, chapters 3.2 and 3.3.2.

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

[0033] In addition to the chain extender (c), a crosslinker (d) can be added to the mixture. The crosslinkers used in the present invention as chain extenders are compounds with a molar mass of less than 400 g / mol, preferably less than 300 g / mol, more preferably between 60 and 250 g / mol, having at least three groups reactive with isocyanates. Examples of crosslinkers are glycerin, trimethylolpropane, pentaerythritol, and triethanolamine. Other possible low molecular weight crosslinkers are described, for example, in "Polyurethane Handbook", Carl Hanser Verlag, 2004, Vol. 1, No. 1, pp. 111-114, 1999. nd 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 crosslinking agent (d) is added to the mixture of the present invention. In a preferred embodiment, the mixture comprises 1 to 8 wt. %, more preferably 2 to 5 wt. %, of at least one crosslinking agent, based on the total weight of components a) to (f).

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

[0036] The incorporable amine catalyst has at least one, preferably 1 to 8, and particularly preferably 1 to 2, isocyanate-reactive groups, such as primary amine, secondary amine, hydroxy, amide, or urea groups, preferably primary amine, secondary amine, or hydroxy groups. Incorporable amine catalysts are primarily used in the production of low-emission polyurethanes, particularly for use in the automotive interiors sector. These catalysts are known and are described, for example, in EP 1 888 664. They include compounds containing, preferably, one or more tertiary amino groups in addition to isocyanate-reactive groups. It is preferred that at least one tertiary amino group of the incorporable catalyst has at least two aliphatic hydrocarbon moieties, preferably having 1 to 10 carbon atoms per moiety, particularly preferably having 1 to 6 carbon atoms per moiety. It is particularly preferred that the tertiary amino group has two moieties independently selected from methyl and ethyl moieties, and another organic moiety. Examples of incorporable catalysts that can be used are bisdimethylaminopropyl 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-aminoethoxyethanol), 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(aminoethyl ether), 3-dimethylaminoisopropyldiisopropanolamine, and mixtures thereof.

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

[0038] Suitable basic amine catalysts for the preparation of delayed action catalysts are described, for example, in "Polyurethane Handbook", Carl Hanser Verlag, 2002. nd edition 1994, chapter 3.4.1. Examples of these are amidines such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, N-methyl-, N-ethyl-, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, N,N,N',N'-tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl) Examples of suitable catalysts include N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane, preferably 1,4-diazabicyclo[2.2.2]octane, and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyl- 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 with isocyanates are used here; an example is N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine. The catalysts can be used individually or in the form of mixtures.

[0039] The carboxylic acids used preferably have a molar mass of less than 300 g / mol. It is particularly preferred to use saturated and unsaturated aliphatic monocarboxylic acids having 1 to 18 carbon atoms, such as formic acid, acetic acid, cyanoacetic acid, or 2-ethylhexanoic acid, aromatic carboxylic acids, saturated and unsaturated aliphatic dicarboxylic acids or tricarboxylic acids having 2 to 16 carbon atoms, or mixtures thereof. Derivatives of the carboxylic acids mentioned above can also be used. Other preferred carboxylic acids used are those of the general formula HOOC-(CH2) n -COOH dicarboxylic acids, where n is an integer from 2 to 14. Dicarboxylic acids of this type are generally less corrosive. In particular, carboxylic acids used include adipic acid.

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

[0041] Examples of concentrations that can be used for the carboxylic acid salt of the amine catalyst (c) are 0.001 to 10% by weight, preferably 0.05 to 5% by weight, and particularly preferably 0.05 to 2% by weight, 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'-tetramethylbutanediamine, N,N,N',N'-tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo[3.3.0]octane, 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, such as tin(II) acetate, tin(II) octanoate, tin(II) ethylhexanoate, and tin(II) laurate, and dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate, and also bismuth carboxylates, such as bismuth(III) neodecanoate, bismuth 2-ethylhexanoate, and bismuth octanoate, or mixtures thereof.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, particularly preferably an incorporable delayed action catalyst.

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

[0045] As the flame retardant (f), generally, all flame retardants known from the prior art can be used.Suitable flame retardants are, for example, bromate esters, brominated ethers or brominated alcohols, such as dibromoneopentyl alcohol, tribromoneopentyl alcohol and 2-(2-hydroxyethoxy)ethyl 2-hydroxypropyl 3,4,5,6-tetrabromophthalate (PHT-4-diol™), 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)ethylenediphosphate, dimethylmethanephosphonate, diethanolaminomethylphosphonic acid diethyl ester, and commercially available halogenated flame-retardant polyols. Further phosphates or phosphonates such as diethylethanephosphonate (DEEP), resorcinol bis(diphenylphosphate) (RDP), triethylphosphate (TEP), dimethylpropylphosphonate (DMPP), diphenylcresylphosphate (DPK) can be used as liquid flame retardants. In a preferred embodiment, the flame retardant comprises at least one group reactive towards isocyanates as a hydroxyl group (-OH) and / or comprises a molecular weight of at least 350 g / mol.

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

[0047] In a preferred embodiment of the present invention, the flame retardant (f) comprises at least one flame retardant that is liquid at room temperature. RDP, TCPP, TEP, DEEP, DMPP, DPK, PHT4 Diol™, brominated ethers, and tribromoneopentyl alcohol, particularly TCPP, TEP, and PHT4 Diol™, especially TCPP, are particularly preferred as liquid flame retardants. In a particularly preferred embodiment, the flame retardant (c) comprises a phosphorus-containing flame retardant, the phosphorus content of which is preferably 0.1 to 3 wt. %, more preferably 0.1 to 1 wt. %, and particularly preferably 0.1 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) is 2 to 20% by weight, preferably 3 to 18% by weight, particularly preferably 4 to 16% by weight, even more preferably 4 to 10% by weight, and particularly preferably 4 to 8% by weight, based on the total weight of components (a) to (f).

[0049] As the blowing agent (g), any blowing agent known in the field of polyurethanes can be used. These may include chemical blowing agents and / or physical blowing agents. These blowing agents are described, for example, in "Polyurethane Handbook", Carl Hanser Verlag, 2004, Vol. 1, No. 1, pp. 117-119, 2004. ndThe term "chemical blowing agent" is described in the 1994 edition, chapter 3.4.5. Here, the term "chemical blowing agent" refers to a compound that forms a gaseous product upon reaction with an isocyanate. Examples of these blowing agents are water and carboxylic acids. The term "physical blowing agent" refers to a compound that is dissolved or emulsified in the starting materials of the polyurethane-forming reaction and evaporates under the conditions for polyurethane formation. These include, for example, hydrocarbons, halogenated hydrocarbons, halogenated hydroolefins, and other compounds, such as 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 used is preferably such that the density of the resulting polyurethane foam is 10 to 850 g / L, particularly 20 to 800 g / L, and especially 25 to 500 g / L. It is particularly preferred to use a water-containing blowing agent, and more preferably, the blowing agent (g) consists of water.

[0050] Furthermore, fillers and / or polyurethane additives (h) can be used. Any fillers and additives known in the production of polyurethanes can be used. Examples include surface-active substances, foam stabilizers, cell regulators, mold release agents, inorganic and organic fillers, dyes, pigments, hydrolysis stabilizers, fungistatic and bacteriostatic substances. These substances are known and can be found, for example, in "Polyurethane Handbook", Carl Hanser Verlag, 2004, Vol. 1, No. 1, pp. 117-119, 2004. nd edition 1994, chapters 3.4.4 and 3.4.6 to 3.4.11.

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

[0052] For the manufacture of battery modules according to the present invention, the reaction mixture according to the present invention can flow through the gaps between adjacent electric cells and settle to a horizontal height around the electric cells and in the gaps or spaces defined between the electric cells. For example, the potting composition can be poured into a battery case with the electric cells disposed therein. The liquid potting composition has sufficient fluidity before curing to allow the liquid potting composition to flow through the gaps between adjacent electric cells and / or the spaces defined by the gaps between the electric cells and the battery case. The liquid reaction mixture has sufficient fluidity to settle to a substantially horizontal height before curing to form the potting material.

[0053] In a preferred embodiment, the electric cell is cleaned, for example by plasma treatment, before being contacted with the reaction mixture according to the invention.

[0054] The potting material of the present invention exhibits very good adhesion to steel surfaces, particularly metals such as Hilumin. This reduces the formation of undesirable gaps between the cells and the potting material, improving flame retardancy, vibration damping, and impact absorption. This allows for the addition of a smaller amount of flame retardant while maintaining flame retardancy. Meanwhile, the smaller amount of flame retardant improves the mechanical properties of the potting material. Furthermore, the electrical cells are thermally insulated from one another, and the potting material of the present invention exhibits high impact absorption and vibration damping properties. Furthermore, the potting material provides structural rigidity and stability to the entire battery module. Furthermore, low heat is generated during the production of the foam of the present invention, thereby protecting individual battery cells from excessive thermal stress during the manufacturing process.

[0055] The invention will now be described with reference to examples.

[0056] Working Example: raw materials Polyol 1: A polyetherol having a number average molecular weight of 2000 g / mol, a functionality of 2, and an OH# of 55 mg KOH / G Polyol 2: a polyether triol having a number average molecular weight of 700 g / mol, a functionality of 3, and based on glycerin and propylene oxide; OH# of 239 mg KOH / g Polyol: A polyetherol based on TMP and propylene oxide with a functionality of 3:3 and an OH# of 860 mg KOH / g. Polyol 4: A polyetherol based on ethylene diamine and propylene oxide with a functionality of 4 and an OH# of 753 mg KOH / g Crosslinker 1: Glycerin, 99.7% purity Crosslinker 2: Triethanolamine: 85% triethanolamine and 15% monoethanolamine Additive 1: Aerosil® 200, a fumed silica from Evonik Additive 2: Zinc stearate purchased from SigmaAldrich Additive 3: Titanium dioxide, pigment, nucleating agent Additive 4: Vorasurf® DC5160: Foaming foam surfactant from Dow Chemicals Additive 5: 2,2,4-trimethyl-1,3-pentanediol diisobutyrate Catalyst 1: Lupragen N 201, an amine catalyst from BASF Chain extender 1: Monoethylene glycol Chain extender 2: Diethylene glycol Chain extender 3: 1,4-butanediol Chain extender 4: Diethyltoluenediamine (EthaCure® 100 from Abermale) Chain extender 5: Dipropylene glycol Flame Retardant (FR): Lupragen® TCPP: Tris(2-chloroisopropyl)phosphate, a flame retardant from ICL; Water: Tap water Isomer: Polymeric MDI with an average functionality of 2.7 and an NCO value of 31.5

[0057] Polyurethane foams were prepared according to the formulations given in Tables 1 and 2 and their adhesion properties were tested according to the following test procedures:

[0058] Determining the adhesion of foam systems to steel surfaces Specimen preparation:

[0059] Materials used: - Metal specimens 25 x 100 mm thick, cleaned with isopropanol, with a thickness of 0.5 to 2 mm - A foaming container with a diameter of 103 mm and a height of 10 mm - Support with a diameter of 103 mm and a height of 10 mm - A separating weight wrapped in Teflon foil, with dimensions of 60 x 20 x 150 mm width x height x length and a weight of 1300 g. - A weight with dimensions of 40 x 20 x 150 mm (W x H x L) and a weight of 870 g - A spacer with dimensions of 30 x 0.5 x 40 mm (width x height x length) - Coesfeld towbar

[0060] Bonding setup for foam-based and metal specimens To test for adhesion of a foam system to a metal surface, a metal specimen was thoroughly wetted from below on one side against the target surface with the foaming foam system. In this test setup, the foaming container was positioned on a flat surface with the opening facing up, and a separating weight was placed from the end to the center of the foaming container, as shown in Figures 1 and 2. The metal specimen was placed on a support with spacers and locked with the weight. The free end of the metal specimen was positioned above the foaming container with an overlap length of 3.0 cm.

[0061] Sample preparation The foam system was freshly prepared in a beaker by dispensing the polyol component, adding the isocyanate component, and then mixing for 10 seconds at 1920 rpm with a Vollrath stirrer. 23 g of fresh foam system was then poured into the foaming container. A separating weight was attached to the foaming container with the fresh foam system, and a metal specimen was placed above the foaming container so that the overlap length with the foaming container was 30 mm. The fresh foam system began to rise, completely wetting the metal specimen from below. Excess foam system rose to the sides of the metal specimen but did not wet it from above. After the foam system cured, the separating weight was removed, and the composite of the foaming container, foam system, and bonded metal specimen was stored for 2 days at 20°C and 50% relative humidity and then tested in a tensile test.

[0062] Tensile Testing of Foam-Based and Metal Specimens The tensile test was carried out according to Figure 3. The composite of the foaming container, the foam system, and the bonded metal specimen was clamped vertically in a tractor. Then, the metal specimen was cut from the foam system at an angle of 180° with a pre-force of 1 N and a pulling rate of 20 mm / min. The generated force was detected by a load cell. The maximum force of the tensile test was recorded, and the average value from three repeated tests was calculated for evaluation.

[0063] Cup Form Test Setup A cup foam test of the mixed polyol and isocyanate components is performed at ambient temperature. The polyol components are homogenized before use. A total of 260 g of the polyol and isocyanate mixture is added to a 1290 ml PP cup, starting with the polyol and then the isocyanate components. A stopwatch is started and the composition is mixed at 1920 rpm for 10 seconds. The reaction mixture is poured into an 860 ml foaming beaker. After 10 minutes, the foam rising outside the beaker is cut with a knife without removing the top. After another 10 minutes, the top of the foam in the cup is removed to determine whether the foam core has turned brownish.

[0064] [Table 1]

[0065] Formulation C1 was a polyurethane foam (equivalent to Sample 1 of EP 3753056) that has been disclosed in the state-of-the-art literature and can be used to encapsulate electrical cells. Adhesion to Hilumin® substrates according to the described test method shows a low value of 73N. Formulation C2 contains 1 weight percent of a chain extender in the polyol component. This directly leads to increased adhesion to Hilumin®, as shown by the value of 91N. When the amount of chain extender in the polyol component was higher (formulations C3, C4, and C5), the values ​​from the adhesion test were even higher, all nearly double the value of C1. Example C5 contained a mixture of two chain extenders, and even in this case, the adhesion test results were much higher compared to those of C1. Therefore, it is shown that formulations containing at least one chain extender have improved adhesion to Hilumin® substrates, which is desirable for potting electrical cells.

[0066] C6 has the same polyol and isocyanate components as C4. The difference between C6 and C4 is the index. C4 has an index of 90.5, while C6 has an index of 100.5, which means that the isocyanate content is higher. In both examples, the values ​​from the adhesion test for C4 and C6 are more than double those of C1, indicating that the effect of the chain extender in improving adhesion to the Hilumin® substrate is effective for indexes below and above 100.

[0067] The same was demonstrated for formulations C7 and C8, in which different chain extenders were used. 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 higher than those of C1. By using the same polyol component but increasing the index (which was the case for example C8), the values ​​from the adhesion test are still at a very high level.

[0068] [Table 2]

[0069] C9 is an example with 5 parts of an aromatic diamine as a chain extender. It was observed that the viscosity of this formulation increased too quickly after mixing it with the isocyanate component, making it impossible to perform adhesion testing on this formulation. By lowering the amount of diamine and combining it with an OH-terminated chain extender (E1), it was possible to perform testing, and very high adhesion values ​​were measured, more than three times those from Example C1. E1 demonstrates that by combining an OH-terminated chain extender with a small amount (less than 5 parts) of an aromatic diamine, it is possible to improve adhesion to Hilumin® substrates.

[0070] In E2 and C10, a larger amount of chain extender was applied. E2, with a chain extender concentration of 11.4 parts by weight based on components a)-(f), still produced a suitable foam with a white core, while C10, with a chain extender concentration of 17.2 parts by weight based on components a)-(f), showed a brownish core, indicating a higher temperature during foam formation. Temperature measurements within the foam showed a core temperature approximately 20°C lower in E2 compared to the foam with C10 after 5 minutes of reaction time. This higher temperature could potentially damage the electrical cell during potting. [Brief explanation of the drawings]

[0071] [Figure 1] FIG. 1 shows a test of the adhesion of a foam system to a metal surface. [Figure 2] FIG. 1 shows a test of the adhesion of a foam system to a metal surface. [Figure 3] FIG. 1 shows a tensile test.

Claims

1. A battery module in which an electrical cell is potted in a potting material, and the potting material is a) One or more organic polyisocyanates, b) One or more polymer compounds having at least two isocyanate-reactive hydrogen atoms, c) A chain extender comprising an O-H chain extender (c1) and an aromatic diamine curing agent (c2), in an amount of 0.5 to 15% by weight based on the total weight of components a) to f), d) Selectively one or more crosslinking agents, e) One or more catalysts, f) One or more flame retardants in an amount of 2 to 20% by weight based on the total weight of components a) to f), g) At least one type of foaming agent, and h) Optionally fillers and / or polyurethane additives A battery module obtained by mixing the following to generate a reaction mixture, and then curing the reaction mixture.

2. The battery module according to claim 1, wherein the one or more polymer compounds (b) having at least two isocyanate-reactive hydrogen atoms comprises a polyetherol (b1) having a functional value of 2 to 4 and a hydroxyl value of 20 to 60 mg KOH / g.

3. The battery module according to claim 2, wherein the polyetherol (b1) comprises at least 80% primary hydroxyl groups.

4. The battery module according to claim 1 or 2, wherein the organic polyisocyanate (a) comprises at least one isocyanate selected from the group consisting of monomer MDI, polymer MDI, MDI-based prepolymer, or a mixture of at least two of these.

5. The battery module according to claim 1 or 2, wherein the isocyanate index is 80 to 120.

6. The battery module according to claim 1 or 2, wherein the content of monomer MDI and polymer MDI in component (a), which includes monomer and polymer MDI (a-1) used in the production of the polyisocyanate prepolymer, is at least 35% by weight based on the total weight of components (a) to (f).

7. The battery module according to claim 1 or 2, wherein the OH chain extender (c1) is selected from the group consisting of monoethylene glycol, diethylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, or mixtures thereof.

8. The battery module according to claim 1 or 2, 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 of the OH chain extender (c1) to the aromatic diamine curing agent (c2) is 200:1 to 1:

1.

10. The battery module according to claim 1 or 2, wherein the flame retardant includes a liquid flame retardant.

11. The battery module according to claim 1 or 2, wherein the flame retardant comprises a phosphorus-based flame retardant, and the phosphorus content is 0.1 to 1% by weight based on the total weight of components (a) to (f).

12. The battery module according to claim 1 or 2, wherein the foaming agent includes water.

13. The density of the potting material is 50-600 g / dm ３ The battery module according to claim 1 or 2.

14. The battery module according to claim 1 or 2, wherein component b) comprises a polymer polyol.

15. The battery module according to claim 1 or 2, wherein the content of at least one polymer polyol based on the total weight of compounds (a) to (f) is 2 to 30% by weight.

16. The battery module according to claim 1 or 2, wherein component (e) comprises a delay-acting catalyst.

17. A method for manufacturing a battery module, The steps include providing a battery case in which electric cells are arranged, which defines the space between adjacent electric cells, a) One or more organic polyisocyanates, b) One or more polymer compounds having at least two isocyanate-reactive hydrogen atoms, c) A chain extender comprising an O-H chain extender (c1) and an aromatic diamine curing agent (c2), in an amount of 0.5 to 15% by weight based on the total weight of components (a) to (f), d) Selectively one or more crosslinking agents, e) One or more catalysts, f) One or more flame retardants in an amount of 2 to 20% by weight based on the total weight of components a) to f), g) At least one type of foaming agent, and h) Optionally fillers and / or polyurethane additives The steps include obtaining a reaction mixture obtained by mixing the following, The steps include inserting the reaction mixture into the space between the adjacent electric cells and curing the reaction mixture. Methods that include...

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