Thermally conductive two-component resins based on carbodiimide chemistry

Abstract

The invention relates to a method for producing a thermally conductive resin obtained by mixing a carbodiimide component (A) and at least one carbodiimide-reactive component (B) to form a reaction mixture and curing the reaction mixture, wherein the carbodiimide component (A) comprises at least one carbodiimide (a1), optionally at least one diluent (a2), at least one filler (a3) selected from the group consisting of at least one surface-modified aluminum hydroxide, at least one alumina or mixtures thereof; and the carbodiimide-reactive component (B) comprises at least one organic compound (b1) comprising at least two hydrogen atoms reactive to carbodiimide groups and at least one filler (b2) and optionally at least one catalyst (b3), at least one filler selected from the group consisting of at least one surface-modified aluminum hydroxide, at least one aluminum oxide or mixtures thereof wherein the molar ratio of carbodiimide groups in the carbodiimide compound (A) to reactive hydrogen atoms in component (B) is in the range of 1: 2 to 2: 1, the content of the at least one filler (a3) is 70% to 95% by weight, based on the total weight of the carbodiimide component (A), and the content of the at least one filler (b2) is 70% to 95% by weight, based on the total weight of the carbodiimide reactive component (B). The invention also relates to a two-component resin composition comprising a carbodiimide component (A) according to the invention and at least one carbodiimide-reactive component (B); a thermally conductive resin obtained by the method according to the present invention; and a battery module including a module case having a top plate, a bottom plate, and side walls, where the top plate, the bottom plate, and the side walls form an internal space; a plurality of battery cells present in the internal space of the module housing; and a resin layer formed by the method according to the present invention, wherein the reaction mixture is cured in contact with the plurality of battery cells.

Description

[0001] This invention relates to a method for producing a thermally conductive resin having a thermal conductivity of at least 0.8 W / mK, the thermally conductive resin being obtained by mixing a carbodiimide component (A) and at least one carbodiimide reactive component (B) to form a reaction mixture and then curing the reaction mixture, wherein the carbodiimide component (A) comprises at least one carbodiimide (a1), optionally at least one diluent (a2), and at least one filler (a3), the at least one filler being selected from the group consisting of at least one surface-modified aluminum hydroxide, at least one alumina, or mixtures thereof; and the carbodiimide reactive component (B) comprises at least one organic compound (b1) containing at least two hydrogen atoms reactive to a carbodiimide group, at least one filler (b2), and optionally at least one catalyst (b3), the at least one filler being selected from the group consisting of at least one surface-modified aluminum hydroxide, at least one alumina, or mixtures thereof, wherein the polycarbodiimide (a1) is obtained from or can be obtained from a mixture comprising at least one diisocyanate. At least one polyisocyanate (i.1); at least one monofunctional compound selected from the group consisting of monoisocyanates, isocyanate-reactive monofunctional compounds, or mixtures thereof (i.2), wherein the isocyanate-reactive monofunctional compound is selected from the group consisting of monohydric alcohols, monothiols, monoamines, and mixtures of two or more of these isocyanate-reactive monofunctional compounds; and optionally at least one carbodiimide catalyst (i-3); and reacting the mixture to form polycarbodiimide (a1), wherein based on Based on the total weight of the polycarbodiimide (a1), the polycarbodiimide (a1) has an isocyanate content of less than 5% by weight and wherein the molar ratio of the carbodiimide group in the carbodiimide compound (A) to the reactive hydrogen atom in the component (B) is in the range of 1:2 to 2:1, the content of filler (a3) ​​is 70% to 95% by weight based on the total weight of the carbodiimide component (A), and the content of the at least one filler (b2) is 70% to 95% by weight based on the total weight of the carbodiimide reactive component (B). The present invention also relates to a two-component resin composition comprising a carbodiimide component (A) according to the invention and at least one carbodiimide reactive component (B); a thermally conductive resin obtained by a method according to the invention; and a battery module comprising a module housing having a top plate, a bottom plate, and sidewalls, wherein the top plate, the bottom plate, and the sidewalls form an internal space; a plurality of battery cells present in the internal space of the module housing; and a resin layer formed by a method according to the invention, wherein the reaction mixture is cured upon contact with the plurality of battery cells.

[0002] If the energy storage system is used in medium and large-sized devices such as automobiles, battery modules in which a large number of battery cells are electrically connected to each other are used for capacity and performance reasons, or battery packs in which several such battery modules are connected. Designing battery modules or battery packs requires various fasteners, cooling devices, etc., where the cooling devices are designed to dissipate the heat generated during charging and discharging operations. Importantly, heat must be rapidly transferred from individual battery cells to the cooling devices. This is typically achieved by attaching the battery cells to the cooling devices with the aid of a thermally conductive resin. In particular, when battery modules are used in automobiles, they are also exposed to external shocks, such as impacts or vibrations, and high temperature differences, such as from below 0°C to above 100°C, and excellent durability under these conditions must be ensured. Additionally, the thermally conductive resin must exhibit high thermal conductivity, low electrical conductivity, low flammability, and low viscosity during application.

[0003] As described by Frauenhofer et al. (Frauenhofer, M., Gormanns, M., Simon, M., Rütters, M., & Fricke, H. Optimized heat dissipation of energy storage systems. adhesion ADHESIVES+ SEALANTS, 17, 12-17 (2020)), for battery assembly, a thermally conductive resin is applied to a cooling plate. The battery cells / modules are then inserted into the resin. During this movement, the resin is effectively pressed against the surface to be wetted, and great care must be taken not to damage the pressure-sensitive battery cells. Therefore, the flow characteristics of the resin and the resulting pressure must be regulated to prevent any damage to the battery and the cooling plate. This is even more challenging because the resin has a high filler loading. The goal is to formulate a resin that is easily compressible to ensure good wettability, pumpability, and low burden on the application equipment. In this regard, extrusion flow rate (SQF) is a well-known topic in bonding technology, which occurs when joining substrates. When the gap height is small, the pressure in the resin can increase unexpectedly. Therefore, a low SQF pressure is required. SQF is widely accepted to simulate the forces exerted when pressing battery cells / modules into the resin on a cooling plate.

[0004] For example, polyurethane-based thermally conductive adhesives are disclosed in EP 3670558, EP 3835332, WO 2019 / 120924, and WO 2022 / 056096. The solutions according to the prior art typically involve a trade-off between thermal conductivity and mechanical properties, as well as flammability, electrical conductivity, and viscosity during application. This is because, on the one hand, a high content of thermally conductive filler material generally results in good thermal conductivity, low flammability, and low electrical conductivity, but it reduces mechanical properties and makes processing more difficult due to the high viscosity of the reaction mixture.

[0005] Furthermore, battery packs are typically manufactured by battery producers, who are usually not chemical companies. Therefore, it is necessary to minimize the handling of substances harmful to health. Since polyurethane is often produced from isocyanates, which are harmful to health, it is necessary to find harmless alternatives.

[0006] Isocyanate-free polymers are known: for example, US 5,079,326 A discloses a thermosetting resin comprising a reaction product of a polycarbodiimide and at least one crosslinking agent (e.g., 2,4,6-triamino-1,3,5-triazine or 2,4-diamino-6-phenyl-1,3,5-triazine) having two or more active hydrogen groups in its molecule. Thermosetting resins are described as having high heat resistance, high strength, flame retardancy, and good processability. The reaction of carbodiimide (CDI) with an alcohol results in the formation of a polymer having isourea bonds (-NH-C(=NR)-O-). Chemical methods for preparing CDI-containing molecules are extensively described in "Chemistry and technology of carbodiimides", Henri Ulrich, Wiley, Hoboken, USA, 2007. CDI-containing molecules can also be prepared from isocyanates. When a difunctional isocyanate is partially reacted with a monofunctional alcohol, followed by the addition of a phosphacyclopentene-based catalyst, an oligomeric CDI structure can be obtained (WO2015 / 123416 A1). The resulting polycarbodiimide (pCDI) polymer can be used, for example, in electrical and electronic packaging applications or synthetic fiber applications, coating compositions, and / or inks. The oligomeric CDI structure can also be obtained by starting with a combination of a difunctional isocyanate and a monofunctional isocyanate and using a phosphacyclopentene-based catalyst, thus producing a terminally capped polycarbodiimide (WO2015 / 127041 A1). WO2015 / 127041 A1 also discloses compositions comprising these terminally capped polycarbodiimides and polyols. Methods for preparing terminally capped polycarbodiimides and methods for producing polymers comprising the reaction products of terminally capped polycarbodiimides and monomeric acids are disclosed in WO 2015 / 127038 A1. Adhesives based on carbodiimide chemistry are disclosed in WO 2020 / 178380.

[0007] What all the literature has in common is that it first publishes a comprehensive list of the components used and also describes a wide range of suitable mixing ratios of the (terminated) pCDI and reactive compounds used to prepare the final resin. Secondly, none of the literature mentions the use of the resin as a thermally conductive resin.

[0008] The object of this invention is to improve the thermal conductivity and flame retardancy of thermally conductive resins, especially thermally conductive adhesives, by using harmless raw materials, while maintaining high insulation resistance (low electrical conductivity) to avoid electronic short circuits, and at least preserving mechanical properties such as shear strength and maintaining or reducing the viscosity of the reaction mixture, especially maintaining or reducing the extrusion flow rate. These objectives are achieved particularly by using standard raw materials that are readily available and inexpensive.

[0009] This objective has been achieved through a method for producing a thermally conductive resin having a thermal conductivity of at least 0.8 W / mK, the thermally conductive resin being obtained by mixing a carbodiimide component (A) and at least one carbodiimide reactive component (B) to form a reaction mixture and then curing the reaction mixture, wherein the carbodiimide component (A) comprises at least one carbodiimide (a1), optionally at least one diluent (a2), and at least one filler (a3), the at least one filler being selected from the group consisting of at least one surface-modified aluminum hydroxide, at least one alumina, or mixtures thereof; and the carbodiimide reactive component (B) comprises at least one organic compound (b1) containing at least two hydrogen atoms reactive to a carbodiimide group and at least one filler (b3), the at least one filler being selected from the group consisting of at least one surface-modified aluminum hydroxide, at least one alumina, or mixtures thereof, wherein the polycarbodiimide (a1) is obtained from or can be obtained from a mixture of at least one polyisocyanate containing at least one diisocyanate. The mixture comprises: an ester (i.1); at least one monofunctional compound selected from the group consisting of monoisocyanates, isocyanate-reactive monofunctional compounds, or mixtures thereof (i.2), wherein the isocyanate-reactive monofunctional compound is selected from the group consisting of monohydric alcohols, monothiols, monoamines, and mixtures of two or more of these isocyanate-reactive monofunctional compounds; and optionally at least one carbodiimide catalyst (i-3); and reacting the mixture to form a polycarbodiimide (a1), wherein the polycarbodiimide (a1) is based on the... 1) The polycarbodiimide (a1) has an isocyanate content of less than 5% by weight and wherein the molar ratio of the carbodiimide group in the carbodiimide compound (A) to the reactive hydrogen atom in the component (B) is in the range of 1:2 to 2:1, the content of the at least one filler (a3) ​​is 70% to 95% by weight based on the total weight of the carbodiimide component (A), and the content of the at least one filler (b2) is 70% to 95% by weight based on the total weight of the carbodiimide reactive component (B).

[0010] The present invention also relates to a two-component resin composition comprising a carbodiimide component (A) according to the invention and at least one carbodiimide reactive component (B); a thermally conductive resin obtained by a method according to the invention; and a battery module comprising a module housing having a top plate, a bottom plate, and sidewalls, wherein the top plate, the bottom plate, and the sidewalls form an internal space; a plurality of battery cells present in the internal space of the module housing; and a resin layer formed by a method according to the invention, wherein the reaction mixture is cured upon contact with the plurality of battery cells.

[0011] In a preferred embodiment, the cured resin according to the invention has a thermal conductivity of at least 0.8 W / mK, preferably from 1.0 W / mK to 3.0 W / mK, as determined according to ISO 22007-2 at 25°C, and a flame retardancy of V0 according to UL-94 testing. The reaction mixture according to the invention preferably has an extrusion flow rate of <500 N, preferably <300 N, and more preferably <200 N, as determined according to the method described in the Example section.

[0012] Any known carbodiimide (a1) can be used as the carbodiimide. Preferably, each molecule of the carbodiimide contains an average of 1 to 10, more preferably 1.5 to 8, and particularly preferably 2 to 5 carbodiimide groups. The polycarbodiimide (a1) according to the invention is obtained from or can be obtained from a mixture of: (i.1) at least one polyisocyanate comprising at least one diisocyanate; (i.2) at least one monofunctional compound selected from the group consisting of monoisocyanates, isocyanate-reactive monofunctional compounds, or mixtures thereof, wherein the isocyanate-reactive monofunctional compound is selected from the group consisting of monohydric alcohols, monothiols, monoamines, and mixtures of two or more of these isocyanate-reactive monofunctional compounds; and (i.3) at least one carbodiimide catalyst, and the mixture is reacted. The carbodiimide according to the invention contains less than 5%, preferably less than 1.0%, and particularly preferably less than 0.1% isocyanate groups based on the total weight of the carbodiimide (a1). In a preferred embodiment, the isocyanate content is measured by FT-IR measurement.

[0013] Any polyisocyanate known in polyurethane chemistry can be used as the polyisocyanate (i.1). The polyisocyanate (i.1) comprises a diisocyanate. The diisocyanate is preferably selected from the group consisting of aliphatic diisocyanates, aromatic diisocyanates, and mixtures of two or more of these diisocyanates. Specific examples of aliphatic diisocyanate compounds include isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), cyclohexyl diisocyanate (CHDI), tetramethylxylene diisocyanate (TMXDI), and combinations thereof, as well as any isomers of these aliphatic diisocyanate compounds. However, generally, diisocyanate compounds include aromatic diisocyanate compounds. In a preferred embodiment of the resin composition according to the invention, the diisocyanate contained in the polyisocyanate composition according to (i) is an aromatic diisocyanate, preferably selected from the group consisting of: MDI isomers 2,2'-diphenylmethane diisocyanate (2,2'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI) and 4,4'-diphenylmethane diisocyanate (4,4'-MDI) and TDI isomers 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI) and mixtures of two or more of these diisocyanates; more preferably selected from the group consisting of: 2,2-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and mixtures of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate. Preferably, based on the total weight of the polyisocyanate (i.1), the content of diisocyanate in the polyisocyanate is higher than 80% by weight, more preferably higher than 90% by weight, and particularly preferably the polyisocyanate (i.1) is composed of diisocyanate.

[0014] In the synthesis of carbodiimide (a1), a monofunctional compound (i.2) is used, which is a monofunctional compound selected from the group consisting of: monoisocyanates, isocyanate-reactive monofunctional compounds, and mixtures of monoisocyanates and isocyanate-reactive monofunctional compounds. Monoisocyanates involve organic molecules with one isocyanate group, and isocyanate-reactive monofunctional compounds are organic molecules with one isocyanate-reactive group. A certain amount of monofunctional compound (i.2) is required to adjust the molecular weight of carbodiimide (a1). The higher the amount of monofunctional compound (i.2) used to prepare polycarbodiimide, the lower its molecular weight and the lower the content of carbodiimide groups per molecule.

[0015] Monoisocyanates can be aromatic or aliphatic, preferably aromatic. Monoisocyanates can be selected from the group consisting of phenyl isocyanates, toluene isocyanates, naphthyl isocyanates, and mixtures of two or more of these monoisocyanates. Compounds having isocyanate reactive groups are selected from the group consisting of monohydric alcohols, monothiols, monoamines, and mixtures of two or more of these isocyanate reactive monofunctional compounds; that is, compounds having isocyanate reactive groups are preferably organic molecules with a group selected from alcohols, amines, and thiols. Organic substituents can be aromatic or aliphatic, preferably aliphatic, including straight-chain, branched, and cyclic aliphatic substituents. Aliphatic substituents can contain one or more heterogeneous element atoms, preferably selected from the group consisting of nitrogen, oxygen, and sulfur atoms, with oxygen being preferred. The isocyanate reactive group is preferably an alcohol; that is, isocyanate reactive monofunctional compounds are preferably monohydric alcohols, more preferably monofunctional compounds (i.2) are at least monohydric alcohols. The total number of carbon atoms and heteroelement atoms in the organic substituent can vary from 1 to 80, preferably from 2 to 50, and more preferably from 3 to 20. In a preferred embodiment, the monohydric alcohol is selected from the group consisting of: ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, 2-methyl-propan-1-ol, propan-2-ol, 2-ethyl-hexan-1-ol, cyclohexanol, polyethylene glycol (mono-PEG), propylene glycol (mono-PPG), 2-(2-ethoxyethoxy)ethanol, and mixtures of two or more of these monohydric alcohols, preferably selected from the group consisting of: butanol, hexanol, 2-ethylhexan-1-ol, mono-PPG, and mixtures of two or more of these, more preferably the monohydric alcohol comprises mono-PPG or 2-ethyl-hexan-1-ol, more preferably at least mono-PPG or 2-ethylhexan-1-ol. Mono-PEG and mono-PPG are monofunctional alcohols and can be traded under the name Pluriol. ® Obtained from BASF.

[0016] The carbodiimide catalyst (i.3) can be any type of carbodiimide catalyst known to those skilled in the art for the production of polycarbodiimides. In one embodiment of the thermosetting resin composition, the carbodiimide catalyst (i.3) is selected from the group consisting of tertiary amides, basic metal compounds, metal salts of carboxylic acids, non-basic organometallic compounds, and phosphorus compounds. Specific carbodiimide catalysts are disclosed in

[0047] through

[0056] of WO 2015 / 123416 A1, which are incorporated herein by reference. In a preferred embodiment, the carbodiimide catalyst (i.3) comprises at least one phosphacene oxide, wherein the at least one phosphacene oxide has the general formula (I).

[0017] ,

[0018] in

[0019] R 1 Substituted or unsubstituted C1 to C15 hydrocarbon groups;

[0020] R 2 or R 4 It is selected from the group consisting of: hydrogen atoms, halogen atoms (preferably chlorine atoms (Cl)) and C1 to C12 alkyl groups, while R 2 R 4 The other one in R 3 Formation of double bonds;

[0021] R 5 R 6 R 7 ,

[0022] R 8 R 9 It is independently selected from the group consisting of hydrogen atoms, halogen atoms (preferably chlorine atoms) and C1 to C12 alkyl groups.

[0023] Preferably, R 1 Selected from the group consisting of: methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, cyclohexyl, n-dodecyl, phenyl, o-tolyl, m-tolyl or p-tolyl, xylyl, naphthyl, 4-diphenyl, 2-phenylethyl, 2-chloroethyl, 2-methoxy-ethyl, o-chlorophenyl, m-chlorophenyl or p-chlorophenyl, p-methoxyphenyl and p-N,N-dimethylaminophenyl; more preferably, R 1 Selected from the group consisting of C2 to C4 alkyl groups, phenyl groups, or benzyl groups. R 2 or R 4 Not with R 3 The group forming the double bond is preferably H. Preferably, R... 5 To R 9 Independently selected from the group consisting of hydrogen atom, chlorine atom, methyl, ethyl, propyl, isopropyl, and butyl, with methyl being preferred. More preferably, R 5 To R 9 Each is either H or methyl.

[0024] In a preferred embodiment, the phosphacene oxide catalyst is selected from the group consisting of 1-methyl-1-oxo-phosphacene, 1-phenyl-3-methyl-1-oxo-phosphacene, 1-benzyl-3-methyl-1-oxo-phosphacene, 1-ethyl-3-methyl-1-oxo-phosphacene, and mixtures of two or more of these phosphacene oxide catalysts. Preferred catalysts are 1-methyl-1-oxo-phosphacene, 1-phenyl-3-methyl-1-oxo-phosphacene (3-methyl-1-phenyl-2-phosphacene 1-oxide, MPPO), and mixtures of 1-methyl-1-oxo-phosphacene and MPPO, with MPPO being a particularly preferred catalyst.

[0025] As a diluent (a2), an inert liquid molecule of an organic compound (b1) containing at least two hydrogen atoms reactive to the carbodiimide (a1) or other components applied as the carbodiimide (a1) can be used. The purpose of the diluent (a2) is to reduce the viscosity and extrusion flow rate of the mixture of the carbodiimide component (A) and the carbodiimide reactive component (B). Preferably, the boiling point of the diluent, determined at atmospheric pressure, is above 100°C, more preferably above 120°C. Examples of diluents are organic esters or ethers, such as dibutyl ether or butyl acetate. The content of the diluent is variable based on the total weight of components (A) and (B), and depends on both the desired viscosity and extrusion flow rate and its effect on the mechanical properties of the cured resin. If a diluent is applied, preferably 1% to 20% by weight, more preferably 2% to 15% by weight, and particularly preferably 3% to 10% by weight.

[0026] The at least one filler (a3) ​​is selected from the group consisting of at least one surface-modified aluminum hydroxide, at least one alumina, or a mixture thereof. The surface-modified aluminum hydroxide is preferably aluminum hydroxide treated with an alkylsilane. Such surface-modified aluminum hydroxide (a3) ​​is known, for example, as disclosed in WO9932554. Preferably, surface modification can be obtained by reacting a silicon compound with aluminum hydroxide (also abbreviated as "ATH"). Preferably, based on the total weight of the surface-modified ATH (a3), the silane content of the surface-modified ATH (a3) ​​is in the range of 0.01 parts by weight to 0.5 parts by weight, more preferably in the range of 0.05 parts by weight to 0.4 parts by weight. In a preferred embodiment, the silane molecules of the surface-modified ATH do not contain isocyanate reactive groups, i.e., the hydroxyl groups are coordinated and cannot be used to react with isocyanate groups. Preferably, the ATH is crude ATH. The size distribution of the surface-modified ATH (a3) ​​can be unimodal, bimodal, or multimodal. In a preferred embodiment, the size distribution of ATH (a3) ​​is bimodal or trimodal to allow for dense packing of the filler in the binder matrix. Preferably, the surface-modified ATH has a particle size D90 of preferably 50 µm to 200 µm, more preferably 60 µm to 150 µm, and particularly preferably 80 µm to 120 µm. In a particularly preferred embodiment, the surface-modified ATH has at least a bimodal size distribution, wherein 30 wt% to 70 wt% of the surface-modified ATH has a size of 1 µm to 20 µm, and 30 wt% to 70 wt% of the surface-modified ATH has a D90 size of 40 µm to 200 µm, each based on the total weight of the surface-modified ATH.

[0027] The at least one type of alumina is preferably spherical alumina with a particle size D90 preferably in the range of 10 μm to 200 μm, and may be surface-modified or surface-unmodified, preferably surface-unmodified. In a more preferred embodiment, the alumina has at least a bimodal size distribution, wherein 10 wt% to 60 wt%, more preferably 15 wt% to 50 wt%, and particularly preferably 20 wt% to 40 wt% of the alumina has a size of 1 μm to 50 μm, preferably 5 μm to 40 μm, and particularly preferably 10 μm to 30 μm, and 40 wt% to 90 wt%, more preferably 50 wt% to 85 wt%, and particularly preferably 60 wt% to 80 wt% of the alumina has a D90 size of 40 μm to 250 μm, preferably 75 μm to 180 μm, and more preferably 100 μm to 150 μm, each based on the total weight of the alumina. The bimodal particle size distribution can be achieved by mixing two compounds with unimodal distributions.

[0028] The term "particle" in connection with the thermally conductive filler (a3) ​​of the present invention refers to ATH or alumina having a specific particle size DX, based on a particle size distribution in which X% of the particles have a diameter smaller than the DX value. The D50 particle size is the median of the particle size distribution. According to the present invention, the D90 value relates to a quantity distribution in which 90% of the total number of particles have a smaller diameter. The particle size (such as D10, D50, and D90 values) and particle size distribution of powders and powdered materials can be measured using a variety of measurement methods known to those skilled in the art, for example via sieving analysis, sedimentation, or light scattering according to DIN 66165-2:2016-08, such as laser diffraction according to DIN ISO 13321:2004-10. Particle size can be measured by dispersing the powder in a suitable solvent and performing laser diffraction according to ISO 13320:2009 or dynamic light scattering according to ISO 22412:2008.

[0029] Particle size distribution can be reported as intensity distribution, volume distribution, surface area distribution, or number distribution. In the present case, the given particle size of the filler is determined by laser diffraction according to ISO 13320:2009, by dispersing the powder in 2-isopropanol.

[0030] The organic compound (b1) comprising at least two hydrogen atoms reactive to a carbodiimide group is selected from compounds comprising at least one hydroxyl group, at least one carboxyl group, at least one secondary amine group, and / or at least one primary amine group. In a preferred embodiment, compound (b1) may have a number average molecular weight of 62 g / mol to 15,000 g / mol and an average functionality preferably of 1.5 to 8, more preferably 1.8 to 4, even more preferably 1.9 to 3, and particularly preferably 2 to 2.2. Examples of compounds (b1) comprising at least two hydrogen atoms reactive to a carbodiimide group are polyamines (e.g., polyetheramines), polyols (such as polyether polyols or polyester polyols), and polycarboxylate esters (such as polyester polycarboxylate esters).

[0031] Preferred polyamines are polyoxyenamines, also known as polyetheramines. These polyoxyenamines are preferably amine-terminated bifunctional or higher-functional polyepoxides, typically polyethylene oxide or polypropylene oxide, with a number-average molecular weight of at least 350 g / mol, for example, at 350 g / mol. -1 Up to 6000g mol -1 500g mol is preferred. -1 Up to 5100g mol -1 Within the range. Amine-terminated polytetrahydrofuran (PTHF) can also be used. The amine group of the polyetheramine is preferably a primary amine group. Polyetheramines are particularly diamines or triamines. Polyamines are usually prepared by catalytic amination of the corresponding polyol. Such compounds are, for example, produced by Huntsman under the name Jeffamine.® Or by BASF under the name Baxxodur ® Sold as polyetheramine.

[0032] In a preferred embodiment, the at least one organic compound (b1) containing at least two hydrogen atoms reactive to carbodiimide groups comprises at least one polyol having an OH value of 10 mg KOH / g to 100 mg KOH / g and a functionality of 2 to 3.

[0033] For example, polyether alcohols are generated from epoxides; such as propylene oxide and / or ethylene oxide, or from tetrahydrofuran and a starting compound exhibiting hydrogen activity containing 1 to 8, preferably 2 to 6, and more preferably 2 to 4 bound reactive hydrogen atoms, or a mixture of starting molecules containing 1.5 to 8, preferably 1.8 to 6, and more preferably 1.9 to 3.5 bound reactive hydrogen atoms, in the presence of a catalyst. As starting molecules, 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 functionality can be obtained. The effect on functionality, such as the effect of side reactions, is not considered in the nominal functionality. Examples of suitable catalysts are basic catalysts or bimetallic cyanide catalysts, as exemplified in PCT / EP 2005 / 010124, EP 90444 or WO 05 / 090440.

[0034] Polyester alcohols are generated, by way of example, from aliphatic or aromatic dicarboxylic acids and polyols, polysulfide 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 Chapter 3.1 of the "Polyurethane Handbook," 2nd edition, 1993, edited by Guether Oertel, Carl Hanser Verlag Munich.

[0035] In a particularly preferred embodiment of the invention, component (b1) comprises polyether alcohol, and more preferably does not comprise polyester alcohol.

[0036] In a preferred embodiment, compound (b1) comprises at least one polyether polyol, which can be obtained by reacting an initiator molecule with a functionality of at least 2 to 4, more preferably 2 to 3, and particularly preferably 2, with an epoxide. In a preferred embodiment, the polyether polyol comprises a polyether polyol obtainable by reacting at least one initiator molecule with a functionality of 2 with an epoxide, wherein the epoxide comprises preferably at least 70 mol%, more preferably at least 85 mol%, and particularly preferably 100 mol% propylene oxide, and has a hydroxyl value preferably from 20 mg KOH / g to 70 mg KOH / g.

[0037] In addition to polyetheramines, polyether polyols, polyester polyols and polycarboxylate esters, compound (b1) preferably contains chain extenders and / or crosslinking agents.

[0038] The chain extenders used herein can be compounds with a molar mass of less than 200 g / mol, preferably less than 150 g / mol, and more preferably 62 g / mol to 150 g / mol, having two isocyanate-reactive groups, such as -SH, -NH-, or NH2 groups, and preferably -OH groups. According to the invention, if chain extenders are used, they are preferably used in amounts of 0.1% to 20% by weight, more preferably 1% to 10% by weight, and particularly preferably 1% to 5% by weight, each based on the total weight of component (b1). As chain extenders, monoethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentanediol, tetraethylene glycol, dipropylene glycol, cyclohexanediol, and aliphatic or aromatic amine-based chain extenders such as aliphatic or aromatic diamines, such as ethylenediamine, triethylenediamine, and / or diethyltoluenediamine (DETDA) and / or secondary diamines can be used. In a preferred embodiment, the 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 mixtures thereof, with 1,4-butanediol being particularly preferred as the chain extender. Other possible low molecular weight chain extenders are mentioned by way of example in “Polyurethane Handbook”, Carl Hanser Verlag, 2nd edition, 1994, Chapters 3.2 and 3.3.2.

[0039] In addition to or as a substitute for chain extenders, crosslinking agents may be added to the mixture. Crosslinking agents used in this invention are compounds with a molar mass less than 200 g / mol, preferably less than 150 g / mol, having at least three groups reactive to isocyanates. Examples of crosslinking agents are glycerol, trimethylolpropane, pentaerythritol, and triethanolamine; in a preferred embodiment, glycerol is used as the crosslinking agent. Other possible low molecular weight crosslinking agents are mentioned by way of example in Chapters 3.2 and 3.3.2 of the "Polyurethane Handbook," Carl Hanser Verlag, 2nd edition, 1994.

[0040] According to the invention, if chain extenders are used, they are preferably used in amounts of 0.1% to 10% by weight, more preferably 1% to 10% by weight, and particularly preferably 1% to 5% by weight, each based on the total weight of component (b1). In a preferred embodiment, no crosslinking agent is used.

[0041] The at least one filler (b2) is selected from the group consisting of at least one surface-modified aluminum hydroxide, at least one alumina, or a mixture thereof. The surface-modified aluminum hydroxide is preferably aluminum hydroxide treated with an alkylsilane. Such surface-modified aluminum hydroxide is known and disclosed, for example, in WO9932554. The same material disclosed in (a3) ​​can be used as the surface-modified aluminum hydroxide.

[0042] The alumina is preferably spherical alumina with a particle size D90 preferably in the range of 10 μm to 200 μm. The same material disclosed in (a3) ​​can be used as the alumina. In a preferred embodiment, the filler (b2) is the same as the filler (a3).

[0043] If catalyst (b3) is used, any catalyst known to promote isourea bond formation can be used. Preferably, catalyst (b3) is selected from the group consisting of metal-containing catalysts; more preferably, it is selected from the group consisting of alkali metals or alkaline earth metals, preferably Na, K and / or Li, or alkoxides, carboxylates, acetoacetates and / or 2,4-pentanediones of metals selected from Ti, Zr, Hf, V, Cu, Hg, Zn, Sn, Hg, Bi and Pb.

[0044] The preferred catalyst (b3) is selected from the group consisting of: organotin compounds, such as tin (II) salts of organic carboxylic acids, such as tin (II) acetate, tin (II) octoate, 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 bismuth carboxylate, such as bismuth neodecanoate (III), bismuth 2-ethylhexanoate, and bismuth octoate; or mixtures thereof. In a preferred embodiment, catalyst (b3) comprises a tin-based catalyst. A particularly preferred metal-based catalyst is dimethyl dineodecanate. Organometallic compounds may be used alone or in combination with strongly basic amines.

[0045] Preferably, based on the total weight of components A and B, components (A) and (B) each contain less than 50% by weight, more preferably less than 20% by weight, of filler, and particularly preferably contain no filler other than filler (a3) ​​and filler (b2). Examples of possible fillers other than filler (a3) ​​and filler (b2) are known in the field of polyurethane and are disclosed, for example, in Polyurethane Handbook, 2nd edition, 1993, edited by Guether Oertel, Carl Hanser VerlagMunich, Chapter 3.4.7.

[0046] In a preferred embodiment, the content of isocyanate groups in component (A) is less than 3% by weight, more preferably less than 1% by weight, and especially less than 0.1% by weight, each based on the total weight of component (A).

[0047] According to the invention, components (A) and (B) are preferably mixed at a temperature of 5°C to 80°C, more preferably 10°C to 60°C, and particularly preferably 25°C to 40°C to form a reaction mixture, wherein the molar ratio of the carbodiimide group in the carbodiimide compound (A) to the reactive hydrogen atom in component (B) is in the range of 1:2 to 2:1, preferably 1:1.5 to 1.5:1, and particularly 1:1.1 to 1:1.1, and the reaction mixture is cured to form a thermally conductive resin. It is presumed that guanidine groups, O-acylisourea and / or isourea groups are formed during curing. Curing can be carried out at high temperatures, for example, 80°C to 160°C, preferably 100°C to 140°C, and particularly preferably 110°C to 130°C.

[0048] Another aspect of the invention is a two-component resin composition and a thermally conductive resin obtained by the method according to the invention, the two-component resin composition comprising a carbodiimide component (A) as defined herein and at least one carbodiimide reactive component (B).

[0049] The thermally conductive resin according to the invention possesses high thermal conductivity, good flame retardancy, and low electrical conductivity, as well as good mechanical properties such as shear strength, adhesion, elasticity, and a low, temperature-independent modulus in the range of -20°C to 80°C. It also exhibits good processability due to the low abrasiveness, low viscosity, and low extrusion flow rate of the reaction mixture. Furthermore, no compounds classified as harmful are added. These advantages are achieved by using cost-effective standard raw materials.

[0050] The thermally conductive resin according to the invention can be used as a thermally conductive adhesive and can be applied to form a battery module comprising a module housing having a top plate, a bottom plate, and sidewalls, wherein the top plate, bottom plate, and sidewalls form an internal space; a plurality of battery cells present in the internal space of the module housing; and a resin layer formed by the method according to the invention, wherein the reaction mixture is cured upon contact with the plurality of battery cells.

[0051] The present invention will now be described with reference to the embodiments. Example

[0052] raw materials :

[0053] Polyol 1: A propylene glycol propoxylated ethoxylated polymer with an OH value of 29.5 mg KOH / g and a molecular weight of 3410 g / mol. Polyol 2: A propylene glycol propoxylated polymer with an OH value of 55 mg KOH / g and a molecular weight of 1970 g / mol. Polyamine 1: Poly(propylene glycol)-bis-(2-aminopropyl ether) with an amine value of 56.65 mg / g and a molecular weight of 2000 g / mol. Diluent: Butyl acetate TC packing 1: Alkylsilane-treated aluminum hydroxide with a particle size D90 of approximately 100 µm TC packing 2: <![CDATA[Spherical alumina filler with a particle size D90 of approximately 20 µm, sold under the Bestry BAK ® 10 trademark.]]> TC packing 3: <![CDATA[Spherical alumina filler with a particle size D90 of approximately 130 µm, sold under the Bestry BAK ® 90 trademark.]]> Chain extender: 1,4-Butanediol Catalyst 1: Organotin (tin dimethyl dinedecanoate) catalyst pCDI 1: Baltanex W02

[0054] Evaluate the processability of two-component adhesive mixtures. Therefore, components A, B, and mixtures of A and B should have a suitable viscosity and creamy texture for processing, allowing them to be applied to the substrate using appropriate auxiliary tools (scraper, trowel, tubular dispenser, or piston dispenser). One method to evaluate this is by extrusion flow rate.

[0055] Squeeze flow :

[0056] Generally, to measure SQF, a rotationally symmetric cylinder with a diameter D is mounted such that it can move axially. The gap between the bottom surface of the cylinder and the plane is filled with thermally conductive adhesive. In a test where the cylinder descends at a linear velocity v, the force F(h) generated during the axial movement of the cylinder and the gap height h(t) are measured simultaneously. The movement of the cylinder causes the adhesive to be radially extruded from the gap. The maximum hydrostatic pressure in the adhesive occurs on the axis of rotation (r=0). Precise parallelism between the cylinder and the plane is crucial to the quality of the measurement, as is very precise speed control and the measurement of the gap height h(t).

[0057] For patent experiments, the following measurement settings are used:

[0058] • Test speed: v = 1 mm / s

[0059] • The diameter of the cylinder is D = 40 mm; the diameter of the plane is 60 mm.

[0060] • Reduce the initial gap of 5mm to a final gap of 0.3mm;

[0061] • Evaluate SQF force with a gap of 0.5 mm

[0062] • Instrument: Zwicki Z2.5 (ZwickRoell) benchtop testing machine with PC and measurement and control software (testXpert III and testControl II).

[0063] SQF measurements were performed at room temperature immediately after mixing components A and B.

[0064] In all examples, the SQF of component A, component B, and mixtures of components A and B showed an acceptable SQF (pumpability) of less than 500 N.

[0065] Curing :

[0066] Curing varies depending on the raw materials used. With the use of polyamine (see Example 1), the mixture of components A and B hardens directly after mixing. Here, the open time is very short. Formulations from other examples require additional temperatures for curing (120°C for 2 hours).

[0067] thermal conductivity :

[0068] The thermal conductivity of gap filler paste was measured using an apparatus from Linseis according to ASTM D5470. In this measurement, a sample was placed between a hot reference material and a cooled reference material. A heat flow was generated between the reference materials and measured via a thermocouple. Given the sample geometry and the applied heat flow, the thermal resistance was calculated. After determining the thermal resistance, the effective thermal conductivity λ at a given sample thickness was obtained by considering the thickness deviation due to the heat flow. eff Besides the thermal resistance of the sample, this λ eff The value also reflects the contact thermal resistance generated by the surface-to-surface contact between the sample and reference materials. The thermal conductivity λ of the bulk was determined by measuring three different sample thicknesses (e.g., 1 mm, 2 mm, and 3 mm). 主体 The obtained correlation curves show the bulk thermal conductivity without contact thermal resistance. Further measurements to suppress the effects of contact thermal resistance can be performed at higher pressures or by using liquid contact oil.

[0069]

[0070] nm = Not measured.

Claims

1. A method for producing a thermally conductive resin having a thermal conductivity of at least 0.8 W / mK, the method comprising mixing a carbodiimide component (A) and at least one carbodiimide reactive component (B). To form a reaction mixture, and to solidify the reaction mixture. The carbodiimide component (A) comprises (a1) at least one carbodiimide (a2) Optionally at least one diluent, (a3) At least one filler, said at least one filler being selected from the group consisting of: at least one surface-modified aluminum hydroxide, at least one aluminum oxide, or a mixture thereof. And the carbodiimide reactive component (B) contains (b1) At least one organic compound containing at least two hydrogen atoms reactive to a carbodiimide group, and (b2) At least one filler, said at least one filler being selected from the group consisting of: at least one surface-modified aluminum hydroxide, at least one aluminum oxide, or a mixture thereof, and (b3) Optionally at least one catalyst and The polycarbodiimide (a1) mentioned above is obtained from or can be obtained from a mixture of: i.1) At least one polyisocyanate, said at least one polyisocyanate comprising at least one diisocyanate; i.2) At least one monofunctional compound, said at least one monofunctional compound being selected from the group consisting of: monoisocyanates, isocyanate-reactive monofunctional compounds, or mixtures thereof, wherein said isocyanate-reactive monofunctional compound is selected from the group consisting of: monohydric alcohols, monothiols, monoamines, and mixtures of two or more of these isocyanate-reactive monofunctional compounds, and i.3) Optionally at least one carbodiimide catalyst And the mixture is reacted to form the polycarbodiimide (a1), Based on the total weight of the polycarbodiimide (a1), the polycarbodiimide (a1) has an isocyanate content of less than 5% by weight, and The molar ratio of the carbodiimide group in the carbodiimide compound (A) to the reactive hydrogen atom in the component (B) is in the range of 1:2 to 2:

1. Based on the total weight of the carbodiimide component (A), the content of the at least one filler (a3) ​​is from 70% to 95% by weight, and Based on the total weight of the carbodiimide reactive component (B), the content of the at least one filler (b2) is from 70% to 95% by weight.

2. The method according to claim 1, wherein each molecule of the at least one carbodiimide (a1) comprises an average of 1 to 10 carbodiimide groups.

3. The method according to claim 1 or claim 2, wherein the polyisocyanate (i.1) is selected from the group consisting of: 2,2-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and mixtures of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate.

4. The method according to any one of claims 1 to 3, wherein the at least one organic compound (b1) comprising at least two hydrogen atoms reactive to a carbodiimide group is selected from compounds comprising at least two hydroxyl groups, at least two carboxyl groups, at least two primary amine groups, at least two secondary amine groups, or a combination of at least two of the group consisting of hydroxyl groups, carboxyl groups, secondary amine groups and / or primary amine groups.

5. The method according to any one of claims 1 to 4, wherein the at least one organic compound (b1) comprising at least two hydrogen atoms reactive to carbodiimide groups comprises a polyol having an OH value of 10 mg KOH / g to 100 mg KOH / g and a functionality of 2 to 3.

6. The method according to any one of claims 1 to 5, wherein the at least one organic compound (b1) comprising at least two hydrogen atoms reactive to carbodiimide groups comprises a chain extender.

7. The method according to any one of claims 1 to 6, wherein the at least one catalyst (b3) is a metal-containing catalyst.

8. The method according to any one of claims 1 to 7, wherein the at least one filler (a3) ​​and (b2) each comprise aluminum hydroxide treated with an alkylsilane, wherein the aluminum hydroxide treated with the alkylsilane has a particle size D90 of 50 µm to 200 µm as measured by laser diffraction using 2-isopropanol to disperse the powder.

9. The method according to any one of claims 1 to 8, wherein the at least one filler (a3) ​​and (b2) each comprise alumina having a particle size D90 of 10 μm to 200 μm as measured by laser diffraction in 2-isopropanol using a powder dispersion.

10. The method according to any one of claims 1 to 9, wherein the at least one filler (a3) ​​and (b2) each comprise at least one mixture of aluminum hydroxide and aluminum oxide treated with alkylsilane.

11. A two-component resin composition comprising a carbodiimide component (A) as defined in any one of claims 1 to 10 and at least one carbodiimide reactive component (B).

12. A thermally conductive resin having a thermal conductivity of at least 0.8 W / mK, obtained by the method according to any one of claims 1 to 10.

13. A battery module, the battery module comprising a module housing having a top plate, a bottom plate and sidewalls, wherein the top plate, the bottom plate and the sidewalls form an internal space; Multiple battery cells exist in the internal space of the module housing; as well as The resin layer is formed by the method according to any one of claims 1 to 10, wherein the reaction mixture is cured in contact with the plurality of battery cells.

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